Reaction-Diffusion Processes from Equivalent Integrable Quantum Chains
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a function of …的函数 absorption:吸附 acetone 丙酮acrylics丙烯酸树脂 Aerospace 航空 agricultural engineering农业工程agricultural engineer农艺师 Amalgam 汞齐,水银;混合物,交叉ammonia 氨 ammonium nitrate硝酸铵ammonium sulfate硫酸铵 analyte分析物 analytical chemistry分析化学amorphous 非定型的,非晶型的,非结晶的,玻璃状的;无一定目的的,乱七八糟approximate to:接近,趋近 area 面积 argon氩 aromatic 芳香烃的as a whole整体而言 ash纯碱 asphalt沥青a priori:先验的,既定的,不根据经验的,由原因推出结果的,演绎的,直觉的accessory heater 附属加热器accident prevention事故预防accountant会计师,会计,出纳 activity coefficient活度系数actualrate of absorption 实际吸收速率 adiabatic绝热的,不传热的alkane烷烃 ammonia-air mixture 氨气-水混合物ammonium phosphate磷酸铵anhydrous无水的applied Chemistry应用化学aquatic plant 水生植物 artificial人工的 asphaltene沥青油assay分析化验 at right angles to 与…成直角,与…垂直bottoms product塔底产品 baffle-plate折流挡板,缓冲挡板balance 抵消,平衡 barrier障碍物 batch间歇的;benzene苯binary distillation双组分精馏 bioengineering生物工程 bionics(仿生学)biosynthesis生物合成 blower 风机 boundary layer 边界层brick wall 墙壁 brittleness 脆性 bubble-cap tower 泡罩塔Buchner funnel 布氏漏斗 bulk explosive集装炸药 buoyancy force 浮力by virtue of 由于,根据,凭借于 barrel桶(国际原油计量单位)base塔底,基础 biological production生物制品生产biomechanics生物力学 bitumen沥青 blood-flow dynamics血液流动动力学boiling point 沸点 bottom 底部,塔底 branched chain支链烷烃branched-chain(带支链的) bulk chemical 大宗化工产品capillary action毛细管作用 carbon dioxide 二氧化碳capital expenditure 基建投资 carbon skeleton碳骨架capital outlay 费用,成本,基建投资 carrier载体carbon tetrachloride四氯化碳 straightforward简单明了的 catalyst 催化剂catalyst催化剂, catalytic cracking 催化裂化catalytic oxidation催化氧化 chemical additive添加剂centrifuge离心.离心机,离心分离 chemical process safety 化工过程安全chain-shaped链状的 chemical reactor transfer of heat, evaporation, crystallization结晶chain链 chlorofluorocarbon二氯二氟化碳,氟里昂chemical reaction化学反应 circulating gas 循环气civil engineer土木工程师 closed system封闭系统cleansing agent清洗剂 compound化合物close teamwork紧密的团队协作 computer microchip 计算机芯片coefficient系数 concentration difference 浓度差columnar liquid chromatography柱状液相色谱仪 concentration gradient 浓度梯度combustion燃烧 condensate冷凝液,凝缩液commercial proportions 商业规模 condensation冷凝commodity or specialty通用商品或特殊化学品 condenser冷凝器compress压缩 condense凝缩,冷凝computationally intensive计算量大的 constitute取代物,取代基concave (凸的,凸面) continuous:连续的concentration 浓度 convection 对流conduction 传导 convection drying对流干燥conduit导流管), cooling water 冷却水conical funnel 锥形漏斗 coordinating ligand配合体,向心配合体conservation of mass and energy能量与质量守衡定律 corrosive property 腐蚀性constant-rate drying period恒速干燥阶段 cost engineer造价师control volume 控制体 counterpart对应物,配对物cooler 冷却器 cracking of petroleum石油裂解counteract抵消 cracking裂化counter-current逆流 criteria 指标 conversion转化,转化率critical moisture content临界湿湿含量 crude oil原油cake filtration 饼层过滤 capillarity毛细现象,毛细管力 crystal flaw 晶体瑕疵decompose分解,离解,还原,腐烂 depth 深度 derivative衍生物descriptive 描述性的 diagnostic application of computers计算机诊断diammonium hydrogen phosphate磷酸二氢铵 dislocation 错位dispersion model分散模型 dissolve 溶解 distillate product塔顶馏出产品distillate section精馏段 downcomer 降液管 drag forces曳力 drying of Solids 固体干燥drying rate干燥速率 ductility 延展性 dairy牛奶deactivate失活 deep bed filtration 深层过滤 defect structure 结构缺陷demonstrate论证,证明,证实;说明,表明,显示density 密度 density difference密度差 deposit沉积物design engineer设计师 detector检测器 detrimental有害的devastate破坏,蹂躏 discolor变色,脱色drop in pressure 压降 drying gas干燥气体 drying干燥durability 耐久性,寿命,使用期限,强度eddy diffusion涡流扩散 efficiency improvement 效率提高electromagnetic wave 电磁波 Empirical model 经验模型employ采纳,利用 end-of-pipe solution 最终方案energy efficiency 能量效率 environmental health engineering环境健康工程equimolecular counter-diffusion 等分子反向扩散essential oil香精油 ether 乙醚 ethylene epoxidation 乙烯环氧化反应exothermic(放热的,endothermic吸热的,adiabatic绝热的)exotic chemistry 奇异化学explosive炸药 extract 萃取液extract萃取液 eddy 尾流,涡流 electrical conductivity 导电性emission释放物,排放物 emulsifying agent乳化剂energy saving 节约能量 enthalpy 焓 extract phase萃取相environmentally benign processing环境友好加工equilibrium constant 平衡常数 ethyl alcohol乙醇)energy conversion 能量转化falling-rate降速 falling-rate period降速干燥阶段feedstock 进料,原料 fermentation发酵Fick’s Law 费克定律 filter cake 滤饼filter paper 滤纸 filtering medium 过滤介质filtering surface 过滤表面 filtrate 滤液flux(通量,流通量) foodstuff 食品forces of friction 摩擦力 forefront最前线,最前沿fouling污垢,发泡 foundation 基础fraction collector馏分收集器fractional crystallization分步结晶fully developed turbulent flow充分发展湍流 functional group官能团furnace 火炉,燃烧器 fused quartz 熔化的石英factor 因数,因子,系数,比例 family族 feed liquor 进料液fertilizer化肥 fiber纤维 filter cake 滤饼filter 过滤器 filtration 过滤 final-proposal决议Fine chemical 精细化工 first-principles基本原理,基本规则fluid mechanics 流体力学 fluorescence 荧光色,荧光fossil fuel化石燃料 freeze drying冷冻干燥gas diffusivity气体扩散性,气体扩散系数gasoline汽油 general service facilities公用工程gravity重力 gas adsorption 吸收;Gas and Liquid Chromatography气相色谱与液相色谱gasoline汽油 governmental regulation政府规定heat exchanger 换热器 heat requirement热负荷heat-sensitive material 热敏性物质 heavy gas oil重瓦斯油helium氦 HF alkylation氰氟酸烷基化high-efficiency高效的 high-fidelity高保真的 high-performance高性能human-factors engineering人类与环境工程humidity湿度 hydrodynamic model水力学模型hydrogen and methane oxidation 氢气和甲烷氧化反应hydroquinone 对苯二酚 hard hat 安全帽hazard identification 危害辩识, health care保健hearing aid助听器 artificial limb假肢 heat exchange 热交换heats of solution and vaporization溶解热和汽化热 homologous series同系物human medicine人体医学 hydrocarbon naphthene环烷烃hydrogen cyanide氰化氢i feed tray进料板 ibuprofen异丁苯丙酸 ifetime寿命 impurity杂质in the vicinity of 在…附近,靠近..,大约…,在…左右information processing 信息处理injection注射 inorganic salt无机盐 insulation 绝缘inter-phase mass transfer界相际间质量传递is proportional to 与…成比例ideal system 理想系统 In principle从原理而言in the absence of无---存在 inert 惰性物,不参加反应的物质inflection:折射 intensity强度,程度is almost inversely proportional to 几乎与…成反比internal structure 内部结构ketone酮 kilogram千克labor 劳动力 laminar sub-layer 层流底层 latent heat潜热 law 定律 Lewis acid不可再生的路易斯酸liquid mixture 液体混合物 lubricating oil润滑油Latin or Greek stem 拉丁或者希腊词根least-squares-regression最小二乘法 life scientist生命科学家liquid-liquid extraction 液液萃取 locant位次,位标 loss prevention损失预防macroscopic phenomenon 宏观现象 thermal stability热稳定性maintenance expense 维修费 macroscopic particle 宏观的粒子materials science材料科学 magnet 磁铁,有吸引力的人或物matte无光泽的,无光的 mathematical expression steady-state model稳态模型mean value平均值 maximum最大的mechanical disturbance 机械扰动 mechanical, thermal, chemical, electric, magnetic, and optical behavior. (机械性能、热学性能、化学性能、电学性能、磁性能、光学性能)mechanical separation 机械分离) medical electronics医疗电子medical instrumentation医疗器械 medical engineering医学工程,医疗工程membrane technology膜技术 medium 介质metal wall of a tube 金属管壁 membrane module膜组件metallic solid 金属固体 methane甲烷metallurgy 冶金学,冶金术 milliliter毫升micro-reactor 微型反应器 miscible可混合的,可溶的,可搅拌的mobile phase移动相 model identification模式识别moisture content湿含量 molecular diffusion 分子扩散motion of unbound electrons 自由电子的运动 molecular transfer分子传递mount 安装,固定 moving gas stream移动的气流multi-component distillation多组分精馏natural gas天然气 naphtha石脑油near toequilibrium接近平衡 natural and forced convection 自然对流和强制对流neural network神经网络 net flow 净流量nitric acid 硝酸 nitric acid硝酸 nylon尼龙nitrogen oxides氮氧化物 nonlinear-equation-solving technique非线性方程求解技术nomenclature of chemical compound化学化合物的命名法 nuclear power 核能octane number of gasoline汽油辛烷值 of the same order具有同一数量级of enthalpy 焓通量 oil drilling采油operating condition操作条件 oil shale油页岩overhead vapor塔顶汽体 one-pass(单程)oxygenate content 氧含量 operating cost 操作费用or convex(凹的,凹面) organic有机的,有机物的outline描绘,勾勒 output产出,输出,产量oxides of nitrogen 氮氧化物paraffin石蜡,烷烃parent母链,主链penicillin青霉素partial vaporization 部分汽化particle size 颗粒尺寸pharmaceutical intermediate药物中间体pharmaceutical 制药 packed tower 填料塔phaseout消除 packing characteristics填充性质phenomenological model 现象模型 packing material 填料 pump 泵physical process 物理过程 paint涂料physiologists生理学 paraffin石蜡,链烷烃physiologist生理学家 per unit area单位面积plastic塑料 percent conversion百分比转化率plate tower 板式塔 installation 装置 feed 进料 perpendicular to:与----垂直polymers聚合物 Pharmaceutical制药power 动力 phosgene synthesis 光气合成.precipitate 沉淀物 plane chromatography薄层色谱precipitation沉淀,沉析 plant layout工厂布局pressure gradient plant location工厂选址probability of failure失效概率 pollutant 污染物process data historian:过程数据历史编撰师 poor conductor of electricity 不良导电体process engineering过程工程 porous medium 多孔介质process material过程物料(相对最终产品而言的) pretreatment 预处理process-simulation software packages过程模拟软件包 processcontrol(过程控制)product 产物,产品 production line生产线prosthetics假肢器官学 protein蛋白质psychology心理学 pyridine砒啶 purify 精制提纯qualitative定性的 quantitative precision定量的精确 quantitative relation 定量关系radiation 辐射 raffinate萃余液ratio of A to B A与B的比值 rate of diffusion扩散速率reactant 反应物 reaction 反应 separation 分离reaction byproduct 反应副产物 reaction yield反应产率reaction speed反应速度 reaction zone反应区reactive distillation 反应精馏 reactive distillation 反应精馏reactor energy input能量输入 recycle 循环回收reboiler再沸器 vaporization汽化 regression model回归模型.refix前缀 release释放,排放reflect 反射, replacement organ器官移植reflux回流 replication 复制 reforming重整 resistance 阻力regenerate再生 resistance 阻力,阻止replicating prefix重复前缀词 retention volume保留体积retention times保留时间 ring-shaped(环状的)Reynolds number雷诺准数 rules and regulations 规章制度reaction kinetics 反应动力学 reactant 反应物retardation factor保留因子,延迟因子safety experience安全经验 safety knowledge安全知识safety management support安全管理基础知识 safety shoe防护鞋sample样品 sandstone砂岩 sedimentary rock沉积岩 sanitation卫生segment段,片,区间,部门,部分;弓形,圆缺;分割,切断screening筛选,浮选sensor 传感器,探头 seepage渗出物 siltstone泥岩 self-taught自学size distribution 粒度分布 semiconductor 半导体sodium hydroxide 氢氧化钠 sensible heat(sensible heat:显热)solubility,溶解度,溶解性 separation of solids 固体分离solute溶质 settling tank沉降槽 solution溶液 setup 装置solvent make-up 补充溶剂 optimum 最优的 shape 形状solvent 溶剂 soap肥皂solvent-recovery system 溶剂回收系统 solid state physics固体物理学stage-type distillation column级板式精馏塔 soluble可溶解的 solvent溶剂statistical technique 统计技术 specialized group专业组storage仓库 specialty chemical特殊化学品,特种化学品stripping section汽提段,提馏段 spinning electrons 旋转电子structural steels 结构钢 spray chamber 喷淋室substituent取代基 stationary nonvolatile phase静止的不挥发相substitute取代,替代 steam蒸汽suffix后缀 stereoselective立体选择性的surface layer 表面层 straight line:直线surface treatment表面处理 streptomycin(链霉素)surgeon外科医生 styrene苯乙烯suspension 悬浮液 sublime升华supportive or substitute organ辅助或替代器官 synthetic rubber合成橡胶tanker油轮 kerosene煤油 tarry柏油的,焦油的,焦油状的technical competence技术能力 tangible return有形回报terminology术语,词汇 tar sand沥青石thermal conductivity 导热性 technical advance 技术进步thermal diffusion热扩散 technical challenge技术挑战,技术困难total condense全凝器 technical evaluation技术评估tower shell 塔体 Telecommunication 电信toxic有毒的 temperature gradient 温度梯度transport of momentum 动量传递 temperature gradient 温度梯度tray 塔板 temperature level 温度高低turbulent flow 湍流 test mixture测试混合物two-film theory 双膜理论 the Chemical Manufacturers Association化工生产协会two-phase flow两相流 the random motion of molecules 分子无规则运动thermal conduction 热传导 thermodynamic equilibrium热力学平衡 tonnage吨位,吨数,吨产量 top 顶部,塔顶trap 收集,捕集 triple bond三健,三价unconverted reactant未转化的反应物 unabsorbed component未吸收组分 purity纯度urea尿素vacant atomic site 原子空位 vacuum drying真空干燥vapor-liquid contacting device汽液接触装置 Vacuum 真空viscous resistance粘性阻力 valve tray浮阀塔板volatility挥发性 vapor pressure蒸汽压voluntary自愿的,无偿的,义务的;有意的,随意的;民办的 via经,由,通过,借助于 viscosity 黏度waste 废物 wastewater treatment污水处理 waste disposal废物处理water droplet水珠,水滴 water purification水净化wax石蜡 weir溢流堰 with the result that:由于的缘故,鉴于的结果water-cooling tower水冷塔yield 产率,收率。
reaction kinetics 反应动力学reactant 反应物purify 精制提纯recycle 循环回收unconverted reactant 未转化的反应物chemical reactor transfer of heat, evaporation, crystallization 结晶drying 干燥screening 筛选,浮选chemicalreaction 化学反应cracking ofpetroleum 石油裂解catalyst 催化剂,reaction zone 反应区conservation of mass and energy 能量与质量守衡定律technical advance 技术进步efficiency improvement 效率提高reaction 反应separation 分离heat exchange 热交换reactive distillation 反应精馏capital expenditure 基建投资setup 装置capital outlay 费用,成本,基建投资yield 产率,收率reaction byproduct 反应副产物equilibrium constant 平衡常数waste 废物feedstock 进料,原料product 产物,产品percent conversion 百分比转化率ether 乙醚gasoline 汽油oxygenate content 氧含量catalyst 催化剂reactant 反应物inert 惰性物,不参加反应的物质reactive distillation 反应精馏energy saving 节约能量energy efficiency 能量效率heat-sensitive material 热敏性物质pharmaceutical 制药foodstuff 食品gas diffusivity 气体扩散性,气体扩散系数gas adsorption 吸收;absorption:吸附specialty chemical 特殊化学品,特种化学品batch 间歇的;continuous:连续的micro-reactor 微型反应器hydrogen and methane oxidation 氢气和甲烷氧化反应ethylene epoxidation 乙烯环氧化反应phosgene synthesis 光气合成. commercial proportions 商业规模replication 复制sensor 传感器,探头separation of solids 固体分离suspension 悬浮液porous medium 多孔介质filtration 过滤medium 介质filter 过滤器trap收集,捕集Buchner funnel 布氏漏斗Vacuum 真空conical funnel 锥形漏斗filter paper 滤纸area 面积filter cake 滤饼factor 因数,因子,系数,比例viscosity 黏度density 密度corrosive property 腐蚀性particle size 颗粒尺寸shape 形状size distribution 粒度分布packing characteristics 填充性质concentration 浓度filtrate 滤液feed liquor 进料液pretreatment 预处理latent heat 潜热resistance 阻力surface layer 表面层filtering medium 过滤介质drop in pressure 压降filtering surface 过滤表面filter cake 滤饼cake filtration 饼层过滤deep bed filtration 深层过滤depth 深度law 定律net flow 净流量conduction 传导convection 对流radiation 辐射temperature gradient 温度梯度metallic solid 金属固体thermal conduction 热传导motion of unbound electrons 自由电子的运动electrical conductivity 导电性thermal conductivity 导热性poor conductor of electricity 不良导电体transport of momentum 动量传递the random motion of molecules 分子无规则运动brick wall 墙壁furnace 火炉,燃烧器metal wall of a tube 金属管壁macroscopic particle 宏观的粒子control volume 控制体enthalpy 焓macroscopic phenomenon 宏观现象forces of friction 摩擦力fluid mechanics 流体力学flux(通量,流通量)of enthalpy 焓通量eddy 尾流,涡流turbulent flow 湍流natural and forced convection 自然对流和强制对流buoyancy force 浮力temperature gradient 温度梯度electromagnetic wave 电磁波fused quartz 熔化的石英reflect反射,inflection:折射matte 无光泽的,无光的temperature level 温度高低inter-phase mass transfer 界相际间质量传递rate of diffusion 扩散速率acetone 丙酮dissolve 溶解ammonia 氨ammonia-air mixture 氨气-水混合物physical process 物理过程oxides of nitrogen 氮氧化物nitric acid 硝酸carbon dioxide 二氧化碳sodium hydroxide 氢氧化钠actualrate of absorption 实际吸收速率two-film theory 双膜理论concentration difference 浓度差in the vicinity of 在…附近,靠近..,大约…,在…左右molecular diffusion 分子扩散laminar sub-layer 层流底层resistance 阻力,阻止boundary layer 边界层Fick’s Law 费克定律is proportional to 与…成比例concentration gradient 浓度梯度plate tower 板式塔installation 装置feed 进料bottom 底部,塔底solvent 溶剂top顶部,塔顶partial vaporization 部分汽化boiling point 沸点equimolecular counter-diffusion 等分子反向扩散ideal system 理想系统ratio of A to B A 与B 的比值with the result that:由于的缘故,鉴于的结果tray 塔板packed tower 填料塔bubble-cap tower 泡罩塔spray chamber 喷淋室maintenance expense 维修费foundation 基础tower shell 塔体packing material 填料pump 泵blower 风机accessory heater 附属加热器cooler 冷却器heat exchanger 换热器solvent-recovery system 溶剂回收系统operating cost 操作费用power 动力circulating gas 循环气labor 劳动力steam 蒸汽regenerate 再生cooling water 冷却水solvent make-up 补充溶剂optimum 最优的unabsorbed component 未吸收组分purity 纯度volatility 挥发性vapor pressure 蒸汽压liquid mixture 液体混合物condense 凝缩,冷凝binary distillation 双组分精馏multi-component distillation 多组分精馏stage-type distillation column 级板式精馏塔mount 安装,固定conduit 导流管),downcomer 降液管gravity 重力weir 溢流堰vapor-liquid contacting device 汽液接触装置valve tray 浮阀塔板reboiler 再沸器vaporization 汽化condensate 冷凝液,凝缩液overhead vapor 塔顶汽体condenser 冷凝器i feed tray 进料板base 塔底,基础bottoms product 塔底产品condensation 冷凝stripping section 汽提段,提馏段distillate section 精馏段total condense 全凝器distillateproduct 塔顶馏出产品reflux 回流thermodynamic equilibrium 热力学平衡solution 溶液fractional crystallization 分步结晶solubility,溶解度,溶解性soluble 可溶解的solvent 溶剂employ 采纳,利用miscible 可混合的,可溶的,可搅拌的mechanical separation 机械分离)liquid-liquid extraction 液液萃取aromatic 芳香烃的paraffin 石蜡,链烷烃lubricating oil 润滑油decompose 分解,离解,还原,腐烂penicillin 青霉素streptomycin(链霉素)precipitation 沉淀,沉析ethyl alcohol 乙醇)extract 萃取液heat requirement 热负荷solute 溶质extract phase 萃取相baffle-plate 折流挡板,缓冲挡板settling tank 沉降槽centrifuge 离心.离心机,离心分离emulsifying agent 乳化剂density difference 密度差raffinate 萃余液extract 萃取液drying of Solids 固体干燥process material 过程物料(相对最终产品而言的)organic 有机的,有机物的benzene 苯humidity 湿度moisture content 湿含量drying rate 干燥速率critical moisture content 临界湿湿含量falling-rate 降速concave (凸的,凸面)or convex(凹的,凹面)approximate to:接近,趋近straight line:直线constant-rate drying period 恒速干燥阶段convection drying 对流干燥drying gas 干燥气体falling-rate period 降速干燥阶段mean value 平均值vacuum drying 真空干燥discolor 变色,脱色sublime 升华freeze drying 冷冻干燥adiabatic 绝热的,不传热的pressure gradientperpendicular to:与 -- 垂直counter-current 逆流per unit area 单位面积water-cooling tower 水冷塔sensible heat(sensible heat:显热)water droplet 水珠,水滴quantitative relation 定量关系thermal diffusion 热扩散at right angles to 与…成直角,与…垂直by virtue of 由于,根据,凭借于molecular transfer 分子传递balance 抵消,平衡drag forces 曳力a function of …的函数of the same order 具有同一数量级eddy diffusion 涡流扩散is almost inversely proportional to 几乎与…成反比Reynolds number 雷诺准数fully developed turbulent flow 充分发展湍流coefficient 系数In principle 从原理而言exothermic(放热的,endothermic 吸热的,adiabatic 绝热的)triple bond 三健,三价nitrogen oxides 氮氧化物compound 化合物conversion 转化,转化率protein 蛋白质compress 压缩reaction yield 反应产率reaction speed 反应速度one-pass(单程)reactor energy input 能量输入maximum 最大的near toequilibrium 接近平衡output 产出,输出,产量fertilizer 化肥urea 尿素ammonium nitrate 硝酸铵ammonium phosphate 磷酸铵ammonium sulfate 硫酸铵diammonium hydrogen phosphate 磷酸二氢铵ash 纯碱pyridine砒啶polymers 聚合物nylon 尼龙acrylics 丙烯酸树脂via 经,由,通过,借助于hydrogen cyanide 氰化氢nitric acid 硝酸bulk explosive 集装炸药crude oil 原油natural gas 天然气bitumen 沥青fossil fuel 化石燃料seepage 渗出物asphalt 沥青oil drilling 采油gasoline 汽油paint 涂料plastic 塑料synthetic rubber 合成橡胶fiber 纤维soap 肥皂cleansing agent 清洗剂wax 石蜡explosive 炸药oil shale 油页岩deposit 沉积物aquatic plant 水生植物sedimentary rock 沉积岩sandstone 砂岩siltstone泥岩tar sand 沥青石chain-shaped 链状的methane 甲烷paraffin 石蜡,烷烃ring-shaped(环状的)hydrocarbon naphthene 环烷烃naphtha 石脑油tarry 柏油的,焦油的,焦油状的asphaltene 沥青油impurity 杂质pollutant 污染物combustion 燃烧capillarity 毛细现象,毛细管力viscous resistance 粘性阻力barrel 桶(国际原油计量单位)tanker 油轮kerosene 煤油heavy gas oil 重瓦斯油reforming 重整cracking 裂化octane number of gasoline 汽油辛烷值branched-chain(带支链的)materials science 材料科学mechanical, thermal, chemical, electric, magnetic, and optical behavior. (机械性能、热学性能、化学性能、电学性能、磁性能、光学性能)Amalgam 汞齐,水银;混合物,交叉solid state physics 固体物理学metallurgy 冶金学,冶金术magnet 磁铁,有吸引力的人或物insulation 绝缘catalytic cracking 催化裂化structural steels 结构钢computer microchip 计算机芯片Aerospace 航空Telecommunication 电信information processing 信息处理nuclear power 核能energy conversion 能量转化internal structure 内部结构defect structure 结构缺陷crystal flaw 晶体瑕疵vacantatomic site 原子空位dislocation 错位precipitate 沉淀物semiconductor 半导体mechanical disturbance 机械扰动ductility 延展性brittleness 脆性spinning electrons 旋转电子amorphous 非定型的,非晶型的,非结晶的,玻璃状的;无一定目的的,乱七八糟chemical process safety 化工过程安全exotic chemistry 奇异化学hydrodynamic model 水力学模型two-phase flow 两相流dispersionmodel 分散模型toxic 有毒的release 释放,排放probabilityof failure 失效概率accidentprevention 事故预防hard hat安全帽safety shoe 防护鞋rules and regulations 规章制度loss prevention 损失预防hazardidentification 危害辩识,technical evaluation 技术评估safety management support 安全管理基础知识safety experience 安全经验technical competence 技术能力safety knowledge 安全知识design engineer 设计师cost engineer 造价师process engineering 过程工程plant layout 工厂布局general service facilities 公用工程plant location 工厂选址close teamwork 紧密的团队协作specialized group 专业组storage仓库waste disposal 废物处理terminology 术语,词汇accountant 会计师,会计,出纳final-proposal 决议tangible return 有形回报Empirical model 经验模型process control(过程控制)first-principles 基本原理,基本规则regression model 回归模型.operating condition 操作条件nonlinear-equation-solving technique 非线性方程求解技术process-simulation software packages 过程模拟软件包least-squares-regression 最小二乘法statistical technique 统计技术intensity 强度,程度phenomenological model 现象模型model identification 模式识别neural network 神经网络a priori:先验的,既定的,不根据经验的,由原因推出结果的,演绎的,直觉的process data historian:过程数据历史编撰师qualitative 定性的quantitative precision 定量的精确high-fidelity 高保真的computationallyintensive 计算量大的mathematical expression steady-state model 稳态模型bioengineering 生物工程artificial 人工的hearing aid 助听器artificial limb 假肢supportive or substitute organ 辅助或替代器官biosynthesis 生物合成life scientist 生命科学家agricultural engineer 农艺师fermentation 发酵civil engineer 土木工程师sanitation 卫生physiologists 生理学criteria 指标human medicine 人体医学medicalelectronics 医疗电子medicalinstrumentation 医疗器械blood-flow dynamics 血液流动动力学prosthetics 假肢器官学biomechanics生物力学surgeon 外科医生replacement organ 器官移植physiologist 生理学家counterpart 对应物,配对物psychology 心理学self-taught 自学barrier 障碍物medical engineering 医学工程,医疗工程health care 保健diagnostic application of computers 计算机诊断agricultural engineering 农业工程biological production 生物制品生产bionics(仿生学)human-factors engineering 人类与环境工程environmental health engineering 环境健康工程environmentally benign processing 环境友好加工commodity or specialty 通用商品或特殊化学品styrene 苯乙烯ibuprofen 异丁苯丙酸the Chemical Manufacturers Association 化工生产协会as a whole 整体而言emission 释放物,排放物voluntary 自愿的,无偿的,义务的;有意的,随意的;民办的in the absence of 无---存在deactivate 失活bulk chemical 大宗化工产品Fine chemical 精细化工Pharmaceutical 制药segment 段,片,区间,部门,部分;弓形,圆缺;分割,切断tonnage 吨位,吨数,吨产量inorganic salt 无机盐hydroquinone 对苯二酚demonstrate 论证,证明,证实;说明,表明,显示forefront 最前线,最前沿Lewisacid 不可再生的路易斯酸anhydrous 无水的phaseout 消除HF alkylation 氰氟酸烷基化catalytic oxidation 催化氧化governmental regulation 政府规定pharmaceutical intermediate 药物中间体stereoselective 立体选择性的ketone 酮functional group 官能团detrimental 有害的chlorofluorocarbon 二氯二氟化碳,氟里昂carbon tetrachloride 四氯化碳straightforward 简单明了的coordinating ligand 配合体,向心配合体kilogram 千克thermal stability 热稳定性devastate 破坏,蹂躏outline描绘,勾勒membranetechnology 膜技术productionline 生产线dairy 牛奶water purification 水净化ifetime 寿命membrane module 膜组件durability 耐久性,寿命,使用期限,强度chemical additive 添加剂end-of-pipe solution 最终方案closed system 封闭系统substitute 取代,替代technical challenge 技术挑战,技术困难wastewater treatment 污水处理fouling 污垢,发泡surface treatment 表面处理applied Chemistry 应用化学nomenclature of chemical compound 化学化合物的命名法descriptive 描述性的refix 前缀alkane 烷烃family 族carbon skeleton 碳骨架chain 链Latin or Greek stem 拉丁或者希腊词根suffix 后缀constitute 取代物,取代基homologous series 同系物branched chain 支链烷烃parent 母链,主链derivative 衍生物substituent 取代基locant 位次,位标replicating prefix 重复前缀词Gas and Liquid Chromatography 气相色谱与液相色谱analytical chemistry 分析化学moving gas stream 移动的气流heats of solution and vaporization 溶解热和汽化热activity coefficient 活度系数counteract 抵消milliliter 毫升essential oil 香精油test mixture 测试混合物sample 样品helium 氦argon 氩carrier 载体injection 注射stationary nonvolatile phase 静止的不挥发相detector 检测器fraction collector 馏分收集器columnar liquid chromatography 柱状液相色谱仪retention volume 保留体积retention times 保留时间high-performance 高性能mobile phase 移动相high-efficiency 高效的analyte 分析物plane chromatography 薄层色谱capillary action 毛细管作用assay 分析化验fluorescence 荧光色,荧光retardation factor 保留因子,延迟因子。
Category类别Variable变量表1:物种,反应,pdf,预混和燃烧的列表1、Species...物种Massfractionofspecies-n(sp,pdf,orppmx;nv)n种质量分率Molefractionofspecies-n(sp,pdf,orppmx)n种摩尔分数Concentrationofspecies-n(sp,pdf,orppmx)n种浓度LamDiffCoefofspecies-n(sp,dil)n种LamDiff系数EffDiffCoefofspecies-n(t,sp,dil)n种EffDiff系数ThermalDiffCoefofspecies-n(sp)n种热量Diff系数Enthalpyofspecies-n(sp)n种焓species-nSourceTerm(rc,cpl)n种SourceTermSurfaceDepositionRateofspecies-n(sr)n种表面沉积率RelativeHumidity(sp,pdf,orppmx;h2o)相对湿度TimeStepScale(sp,stcm)FineScaleMassfractionofspecies-n(edc)n种精密标度质量分率FineScaleTransferRate(edc)精密标度传输率1-FineScaleVolumeFraction(edc)精密标度体积分率2、Reactions...反应RateofReaction-n(rc)n反应速度ArrheniusRateofReaction-n(rc)n反应阿伦纽斯速度TurbulentRateofReaction-n(rc,t)n反应湍流速度3、Pdf...MeanMixtureFraction(pdforppmx;nv)平均混合分数SecondaryMeanMixtureFraction(pdforppmx;nv)二级平均混合分数MixtureFractionVariance(pdforppmx;nv)平均混合分数变量SecondaryMixtureFractionVariance(pdforppmx;nv)二级平均混合分数变量FvarProd(pdforppmx)fvar测试棒Fvar2Prod(pdforppmx)fvar2测试棒ScalarDissipation(pdforppmx)标量逸散4、Premixed预混和ProgressVariable(pmxorppmx;nv)进展变量5、Combustion...燃烧DamkohlerNumber(pmx or ppmx)StretchFactor(pmx or ppmx)伸长因数TurbulentFlameSpeed(pmx or ppmx)湍流焰速度StaticTemperature(pmx or ppmx)静态温度ProductFormationRate(pmx or ppmx)生成物形成率LaminarFlameSpeed(pmx or ppmx)层流焰速度CriticalStrainRate(pmx or ppmx)临界应变率AdiabaticFlameTemperature(pmx or ppmx)绝热火焰温度UnburntFuelMassFraction(pmx or ppmx)未燃烧燃料质量分率表2:NOx,Soot,andUnsteadyStatisticsCategories(Nox,烟灰和不稳定统计列表)1、NOx...MassfractionofNO(nox)NO质量分率MassfractionofHCN(nox)HCN质量分率MassfractionofNH3(nox)NH3质量分率MolefractionofNO(nox)NO摩尔分率MolefractionofHCN(nox)HCN摩尔分率MolefractionofNH3(nox)NH3摩尔分率ConcentrationofNO(nox)NO浓度ConcentrationofHCN(nox)HCN浓度ConcentrationofNH3(nox)NH3浓度VarianceofTemperature(nox)温度变量VarianceofSpecies(nox)物种变量VarianceofSpecies1(nox)物种1变量VarianceofSpecies2(nox)物种2变量2、Soot...烟灰Massfractionofsoot(soot)烟灰质量分率Massfractionofnuclei(soot)核的质量分率3、UnsteadyStatistics...不稳定统计Meanquantity-n(stat)平均值nRMSquantity-n(stat)均方根值n表3:Phases,DiscretePhaseModel,GranularPressure,andGranularTemperature Categories(相,分散相模型,颗粒压强,和颗粒温度列表)Phases...相Volumefractionofphase-n(mp)n相体积分率DiscretePhaseModel...分散相模型DPMMassSource(dpm)质量源DPMErosion(dpm,cv)腐蚀DPMAccretion(dpm,cv)增长DPMXMomentumSource(dpm)X动量源DPMYMomentumSource(dpm)Y动量源DPMZMomentumSource(dpm,3d)Z动量源DPMSwirlMomentumSource(dpm,2dasw)旋转动量源DPMSensibleEnthalpySource(dpm,e)显焓源DPMEnthalpySource(dpm,e)焓源DPMAbsorptionCoefficient(dpm,rad)吸收系数DPMEmission(dpm,rad)发散DPMScattering(dpm,rad)散射DPMBurnout(dpm,sp,e)燃尽DPMEvaporation/Devolatilization(dpm,sp,e)蒸发/液化DPMConcentration(dpm)浓度DPMspecies-nSource(dpm,sp,e)n种源GranularPressure...颗粒压强phase-nGranularPressure(emm,gran)n相颗粒压强GranularTemperature...颗粒温度phase-nGranularTemperature(emm,gran)n相颗粒温度表4:Properties,WallFluxes,UserDefinedScalars,andUserDefinedMemory Categories(性质,间隔层通量,用户定义标量和用户定义存储列表)Properties...性质MolecularViscosity(v)分子粘度MolecularViscosityofphase-n(v,mp)n相分子粘度Diameterofphase-n(mixoremm)n相直径ThermalConductivity(e,v)导热性SpecificHeat(Cp)(e)比热SpecificHeatRatio(gamma)(id)比热比GasConstant(R)(id)气体常数MolecularPrandtlNumber(e,v)分子普朗特数MeanMolecularWeight(seg,pdf)平均分子量SoundSpeed(id)声速WallFluxes...间隔层通量WallShearStress(v,cv)间隔层剪应力phase-nWallShearStress(v,cv,emm)n相间隔层剪应力X-WallShearStress(v,cv)X剪应力Y-WallShearStress(v,cv)Y剪应力Z-WallShearStress(v,3d,cv)Z剪应力phase-nX-WallShearStress(v,cv,emm)n相X剪应力phase-nY-WallShearStress(v,cv,emm)n相Y剪应力phase-nZ-WallShearStress(v,3d,cv,emm)n相Z剪应力Axial-WallShearStress(2da,cv)轴向剪应力Radial-WallShearStress(2da,cv)径向剪应力Swirl-WallShearStress(2dasw,cv)旋向剪应力SkinFrictionCoefficient(v,cv)表面摩擦系数phase-nSkinFrictionCoefficient(v,cv,emm)n相表面摩擦系数TotalSurfaceHeatFlux(e,v,cv)总表面热负荷RadiationHeatFlux(rad,cv)辐射热负荷SurfaceIncidentRadiation(do,cv)表面入射辐射SurfaceHeatTransferCoef.(e,v,cv)表面传热系数SurfaceNusseltNumber(e,v,cv)表面努珊数SurfaceStantonNumber(e,v,cv)表面斯坦顿数UserDefinedScalars...用户定义标量Scalar-n(uds,nv)n标量DiffusionCoef.ofScalar-n(uds)n标量扩散系数UserDefinedMemory...用户定义存储udm-n(udm)CellInfo,Grid,andAdaptionCategories(控制体积,网络节点,配合列表)CellInfo...控制体积CellPartition(np)控制体积分区ActiveCellPartition(p)主动控制体积分区StoredCellPartition(p)存储控制体积分区CellId(p)控制体积标识CellElementType控制体积要素种类CellZoneType控制体积区域种类CellZoneIndex控制体积区域指数PartitionNeighbors邻元素分区Grid...网格节点X-Coordinate(nv)X坐标Y-Coordinate(nv)Y坐标Z-Coordinate(3d,nv)Z坐标AxialCoordinate(nv)轴向坐标RadialCoordinate(nv)径向坐标XSurfaceAreaX表面面积YSurfaceAreaY表面面积ZSurfaceArea(3d)Z表面面积XFaceAreaX端面面积YFaceAreaY端面面积ZFaceArea(3d)Z端面面积CellEquiangleSkew控制体积等角度倾斜CellEquivolumeSkew控制体积等量倾斜CellVolume控制体积容量2DCellVolume(2da)2D控制体积容量CellWallDistance控制体积间隔层距离FaceHandedness端面旋向性FaceSquishIndex端面挤压指数CellSquishIndex控制体积挤压指数GridCategory(Turbomachinery-SpecificVariables)andAdaptionCategory(网络节点列表(涡轮积类变量)和配合列表)Grid...网络节点MeridionalCoordinate(nv,turbo)经纬坐标AbsMeridionalCoordinate(nv,turbo)绝对值经纬坐标SpanwiseCoordinate(nv,turbo)Abs(H-C)SpanwiseCoordinate(nv,turbo)Abs(C-H)SpanwiseCoordinate(nv,turbo)PitchwiseCoordinate(nv,turbo)AbsPitchwiseCoordinate(nv,turbo)Adaption...配合AdaptionFunction配合功能ExistingValue现存值BoundaryCellDistance控制体积边界距离BoundaryNormalDistance边界标准距离BoundaryVolumeDistance(np)边界容量距离CellVolumeChange控制体积容积变化CellEquiangleSkew控制体积等角度倾斜CellEquivolumeSkew控制体积等容量倾斜CellSurfaceArea控制体积表面面积CellWarpage控制体积折曲ResidualsCategory(残值列表)Residuals...残值MassImbalance质量不稳定PressureResidual(cpl)压强残值X-VelocityResidual(cpl;2dor3d)X速度残值Y-VelocityResidual(cpl;2dor3d)Y速度残值Z-VelocityResidual(cpl,3d)Z速度残值Axial-VelocityResidual(cpl,2da)轴向速度残值Radial-VelocityResidual(cpl,2da)径向速度残值Swirl-VelocityResidual(cpl,2dasw)旋向速度残值TemperatureResidual(cpl,e)温度残值Species-nResidual(cpl,sp)n物种残值Derivatives...导数StrainRate(v)应变速率Derivatives...导数StrainRateofphase-n(v,emm)n相应变速率。
Flame capturing with anadvection-reaction-diffusion modelNatalia Vladimirova†,V.Gregory Weirs†,andLenya Ryzhik‡†ASC/Flash Center,Department of Astronomy&Astrophysics,The Universityof Chicago,Chicago,IL60637,USA‡Department of Mathematics,The University of Chicago,Chicago,IL60637,USAAbstract.We conduct several verification tests of the advection-reaction-diffusionflame capturing model,developed by Khokhlov(1995)for subsonicnuclear burning fronts in supernova simulations.Wefind that energy conservationis satisfied,but there is systematic error in the computedflame speed due tothermal expansion,which was neglected in the original model.We decouplethe model from the full system,determine the necessary corrections for thermalexpansion,and then demonstrate that these corrections produce the correctflamespeed.Theflame capturing model is an alternative to other popular interfacetracking techniques,and might be useful for applications beyond astrophysics.(7March2005)1.Introduction1.1.Modelling aflame as an interfaceFor simulations of systems involvingflames,several strategies for computing theflame are available.If theflame length scale is not much smaller than the computational domain,then highly detailed kinetics models,high-order discretizations,and adequately posed initial and boundary conditions can be used to probe the structural subtleties of theflame.At the other extreme areflames so much smaller than the computational domain they are impossible to resolve numerically;then the most common approach is to model theflame as a discontinuity in the thermodynamic variables.A number of techniques dealing with infinitely thin interfaces are available in the literature[12,9].Among them are front tracking methods,known for better accuracy; level set methods,which easily treat topological changes;and volume-of-fluid methods, which possess an intrinsic conservation property.All these methods do the essentially the same thing:starting with the current position of the interface and its speed of propagation,compute the position at a later time.Each method strikes a different compromise between computational cost,accuracy,development and implementation cost,and other desirable properties.However,few applications can take advantage of the commonality among the interface ers cannot easily swap interface methods in their codes as requirements change–allowing one to use the technique with the best properties for,say,the available computational power,or a new regime of phenomena they want to investigate.When an interface method is incorporated into a physical model,it is encumbered with additional restrictions.For example,the volume of incompatible fluid on both sides of the interface must remain unchanged,or thermodynamic quantities across theflame front must satisfy the Rankine-Hugoniot jump conditions, or a biological interface might set conditions on elasticity or surface charge.The challenge of building a simulation tool involving an interface technique is not in choosing or implementing the technique itself,but in coupling the interface technique with the other physics models.The biggest challenge in representing aflame as an infinitely thin interface is to correctly model the coupling between theflame speed and thermodynamic conditions on each side of theflame.The difficulty is reduced if theflame speed can be assumed to be independent of thermodynamic states and thefluid on both sides sides of the flame can be assumed incompressible.If these conditions are satisfied,the system can be modelled without reconstructing the interface(without determining the precise location of the interface as it crosses each computational cell,)which permits taking full advantage of the level set approach[11].However,if theflame speed depends on the local thermodynamics or the incompressibility assumption is invalid,then interface reconstruction is unavoidable[13].Moreover,modelling a compressiblefluid implies solving the energy equation,which introduces another constraint associated with the interface:the transformation of chemical energy to thermal energy must be consistent with the transformation of unburned mass(reactant)to burned mass(product).1.2.Original ARD modelIn1995Khokhlov developed aflame model which combines the automatic treatment of interface topology with an energy conservation mechanism[7].The easy treatment offlame topology follows from an implicit interface representation.Similar to the level set method where the interface is described by a scalar level set variable,the interface in Khokhlov’s method is described by a scalar reaction progress variable. The value of the reaction progress variable is zero in the reactant,one in the product, and monotonically varies inside a“flame region.”The width of theflame region is much larger than the thickness of the physicalflame it represents;it is set by the model to be several computational zones thick.Unlike the level set variable,which in the vicinity of theflame is interpreted as the signed distance to the interface,but far from the interface has no physical meaning, the reaction progress variable is relevant everywhere.It can be associated with the mass fraction of burned material in a cell.In this way,the reaction progress variable is similar to the volume fraction variable in the volume offluid method.But contrary to the volume fraction variable,the reaction progress variable distributes the interface over several computational cells.The evolution of the reaction progress variable is described by the advection-reaction-diffusion(ARD)equation.The reaction progress variable is advected by the flow,diffuses,and is generated in some simple source term,here called reaction.In the limit of fast reaction rate and small diffusivity(thinflame limit)the advection-reaction-diffusion equation is equivalent to the level set equation and describes the front governed by Huygens’s principle[6,10].The front’s speed of propagation with respect to theflowfield depends on diffusivity and reaction rate.In Khokhlov’s model,however,diffusivity and the reaction rate have very little to do with the physical properties of thefluid.They are artificial parameters chosen with the sole purpose of producing a desiredflame speed and front thickness.The ARD equation is added to a system of equations representing other types of physics,e.g.the Euler equations with a suitable state equation.The ARD model “gets input from physics”through the advection velocity and theflame speed,which can be determined dynamically from the local conditions.Theflame model is coupled back to theflowfield through a source term in the energy equation:the amount of burned material,and consequently the energy released,is proportional to the change in reaction progress variable.1.3.Extending the ARD modelThe original ARD model was designed to represent deflagrations in a white dwarf star,as an initial stage of a Type Ia supernova explosion.Although thefluid in the burned and unburned regions cannot be assumed incompressible because of strong gravitational stratification,the local conditions in the vicinity of theflame are almost incompressible.Near the center of the white dwarf,the thermonuclearflame is extremely thin(10−8–10−6of the star radius),highly subsonic,and is characterized by a small density decrease across theflame(about10%),and essentially no jump in pressure(less than1%)[16].To extend the model to the compressible regime,modifications are required to account for velocity variations on the scale of the interface thickness.Velocity variations come from the density jump between unburned and burnedfluids:when material crosses theflame front it expands and accelerates,resulting in normal velocity variations of the order of theflame speed.The original method was built on the implicit assumption that these velocity variations do not affect the travelling wave speed;the control parameters for the model were chosen based on the properties of the isolated ARD equation(discussed in Sec.2.)Consequently the original ARD model fails to recover the properflame speed unless thermal expansion is negligible.Our solution to this problem is based on a physical interpretation of the ARD equation,which allows us to decouple it from the mass,momentum,and energy equations.This approach is described in Sec.3.We can then study the ARD equation in isolation tofind the effect of thermal expansion and consequent velocity variation on theflame speed,as explained in Sec.4.Knowing the effects of thermal expansion,we suggest modifications to the control parameters of theflame capturing model in Sec.5. With the modifications,the model recovers the desiredflame speed,as demonstrated through verification tests in Sec.6.Section7gives suggestions regarding the model’s use and implementation and potential avenues for improvement.2.Properties of the advection-reaction-diffusion equationThe evolution of the reaction progress variableφis described by the advection-reaction-diffusion equation,1φt+v·∇φ=κ∇2φ+reaction progress variable is scaled so thatφ=0andφ=1represent pure reactant and pure product,respectively.In the absence of advection,the velocity v=0,and the ARD equation describes travelling wave solutions.For a given reaction rate,R(φ),the travelling wave speed s0is determined by the reaction timeτ,and the diffusion coefficientκ.In cases when the dependence R(φ)is simple enough,the travelling wave speed can be obtained analytically.One reaction rate for which the analytical front propagation speed is known is the Kolmogorov-Petrovskii-Piskunov(KPP)reaction rate[8,5],1R(φ)=κ/τ.The KPP reaction rate is often used as a source term in advection-reaction-diffusion models because it makes such models more accessible for rigorous analysis(see reviews[17,1]).Another reaction rate we consider is a reaction rate of“ignition”type,where reaction is impossible until the reaction progress variable reaches some critical value, i.e.R(φ)=0forφ<φ0.Ignition–type reaction terms are widely used to model combustion processes(see review[17]),in particular,for approximating the behavior of Arrhenius-type chemical reaction rates.The original ARDflame-capturing method[7] was developed with a reaction rate of ignition type,specifically,the top-hat reaction rate:R(φ)=0,φ<φ0,R(φ)=R0,φ0≤φ<1,(3)R(φ)=0,φ≥1,where R0is a constant chosen such that the travelling wave speed is s0=κ/τcan always be achieved by multiplying the reaction rate by a constant.)In Appendix1we show the analytical solution of equation(1)with the top-hat reaction rate and v=0,and derive the expression for R0.Another parameter,which can be constructed fromκandτ,has the dimension of√length.We call it the reaction length scaleδ0=Our goal is to solve the ARD equation as one member of a system of equations, in which the velocityfield is computed as part of the solution.In the fully coupled system,exothermic reaction in theflame causes a reduction in the density,i.e.thermal expansion.Mass conservation then requires acceleration of thefluid as it passes through theflame,with consequent alteration of theflame speed.In the next section,we will derive an expression for the velocity profile across the fully coupledflame as a function of the reaction progress variable.Then,using this velocity profile,we will study the ARD equation in isolation.We will show that for a given density ratio,theflame speed and theflame thickness depend on the diffusion coefficient and the reaction time,and we will determine the dependencies,s=s(κ,τ)and l=l(κ,τ).(5) Finally,a comment about terminology and notation.When the velocity profile accounts for thermal expansion,we call s the variable-densityflame speed.The spatially-constant velocityfield does not account for thermal expansion,so we can refer to s0as the isochoricflame speed.The quantities s0andδ0are not directly relevant to the variable-density case,but we still use them as reference quantities, s0≡ κτ,(6) based on diffusivity and reaction time.3.Coupling advection-reaction-diffusionflame model toflow physicsA natural way to couple the ARDflame equation to theflow physics comes from the physical interpretation of the reaction progress variable as the mass fraction of the product.If the rate of conversion from reactant to product isρ˙φ,and q is the energy released per unit mass of convertedfluid,an additional heat release term appears in the energy equation.Then the full system of governing equations becomes,∂ρ∂t +∇(ρvv)+∇P=f,∂ρE∂t+∇·(ρφv)=ρ˙φ,˙φ=κ∇2φ+12is the total energy and e=e(ρ,P)is specific thermal energy,where the functional relationship is specified by the equation of state.Note that by substitutingρ˙φfrom the equation for reaction progress variable into the energy conservation equation,we obtain the conservation of energyρE′=ρ(e−qφ)+ρvvrelease,q,are input parameters in theflame capturing model.The diffusion coefficient κand the reaction timescaleτin the ARD equation are not related to the physical diffusion or reaction,but chosen solely to produce a desiredflame speed and a specified flame width.For a givenflame speed andflame thickness,the diffusion coefficient and the reaction timescale can be found from relations(5),κ=κ(s,l)andτ=τ(s,l).(8) If all goes well,the observedflame speedˆs and thicknessˆl will be the same as the input s and l.Unfortunately,at this point relations(5),and consequently(8),are available only for an isochoricflame.Extension to the compressible regime requires the velocity profile across theflame interface as function of the reaction progress variable,which we develop next.We consider a one-dimensional laminarflame with no external force applied to thefluid.We assume the system(7)has reached a stable travelling wave solution. Then,in the reference frame of the travelling wave,the mass,momentum,and energy conservation equations have a simple algebraic form:ρv=const,ρv2+P=const,(9)v ρ(e−qφ)+P+ρv2˜α(φ),v=v u−s(˜α(φ)−1),(10)P=P u−ρu s2(˜α(φ)−1).Here˜α(φ)is the ratio of the(partially burned)fluid density to the unburnedfluid density and is a function of the reaction progress variable only.The functional relationship˜α(φ)depends on the equation of state.For instance, for the gamma-law equation of state,e=1ρ,and one can derive˜α(φ)=1+11−2ǫ1ǫ2φ ,(11)withǫ1=(γ+1)s2c2u−s2,where c u=assumes a one-dimensional flame propagating to the right,but can be generalized to the multi-dimensional case,v (φ)=v u +n φ∆v f ,where n is the unit normal to the front pointing in the direction of flame propagation.Note that no assumptions have been made on ǫ2,i.e.the parameter ǫ2≈γ−1P u need not be small.The velocity jump ∆v f is a direct consequence of thermal expansion.Thermalexpansion influences the flame speed through two competing effects.On one hand,the burned fluid moves away from the flame at a greater velocity,and this slows the flame.On the other hand,expansion thickens the reaction zone,which increases the amount of fuel burned per unit time;consequently the flame speed is increased.To show these competing effects,we integrate the one-dimensional form of the ARD equation in (7)or the equivalent isolated ARD equation (1),with the velocity profile in (10),and solve for the flame speed,obtaining s =s 0 +∞−∞R d (x/δ0)ρ(φ)dφ,where s 0and δ0are defined in (6).Compared to the isochoric case,the burning region in the variable-density case is wider,leading to a larger integral in the numerator.At the same time,the ratio ρu /ρ(φ)is always greater than one,so the integral in the denominator is also larger.The difference between s and s 0depends both on the distribution of φ(x )across the interface and the density dependence ρ(φ)on the reaction progress variable.In general,the variable-density flame speed can be larger or smaller than the isochoric flame speed.For a general equation of state,an analytic expression for ˜α(φ)might not be available,but simplifications might still be possible.In the zero Mach-number limit,kinetic energy can be neglected in (9).This implies the pressure is constant across the flame,and the energy equation reduces to a purely thermodynamic relation.Thus,the state at any stage of reaction (at any φ)can be found from any known state by solvinge (ρ,P )+P4.Numerical solution of isolated ARD equation withφ-dependent velocityNow that we have derived an expression(12)for v(φ)we return to the solution of equation(1)with an advection velocity which accounts for thermal expansion.For some simple reaction rates the variable-densityflame speed can be found analytically.The KPP reaction rate(2)has a single stable point,φ=1,and metastable point,φ=0,and is characterized by the condition that the function R(φ)is positive and convex on the interval0<φ<1.In Appendix2we show that if the velocity is as in(12),there is only one way to connect metastable and stable points on the phase diagram(φ,˙φ).The solution corresponds to theflame speed s=s0for any∆v f<0.Unfortunately,the analytical approach above does not extend to reaction rates with multiple stable and unstable points,and thus cannot be used for reaction rates of“ignition”type,such as the top-hat reaction rate(3).In this section we solve the ARD equation(1)numerically,using theφ-dependent advection velocity(12).This exercise has two purposes.First,we want to verify the independence of theflame speed on the jump∆v f for the KPP reaction rate,and to measure the effect of the jump for the top-hat reaction rate.Doing so,we will consider well-resolved numerical solutions of equation(1).Second,we want to study the effect of spatial resolution.In theflame-capturing model,the ARD equation is used at low spatial resolutions to mimic the discontinuity. Keeping the front thin reduces the effect of background velocity and thermodynamic variations,which are unavoidable in the full system and which might modify the internalflame structure.At the same time,we will keep the time step significantly smaller than both diffusive and advection CFL limits,assuming that in a compressible flow simulation the time step is set by the CFL condition based on the speed of sound. The small time step ensures that numerical errors due to temporal discretization are dominated by spatial discretization errors.We discretize equation(1)using fourth-order central differences in space and the explicit Euler method in time.Thefluid velocity profile is specified by(12).The KPP reaction rate is given in(2)and the top-hat rate in(3).We express resolution in terms of computational cells across the reacting region,b=l/∆x,where l is the width of the isochoricflame(4).The time step is typically∆t=10−3τ,which is at least two orders of magnitude smaller than the diffusive and advection CFL limits.We repeated a number of cases with different time step sizes and using the 3rd-order Adams-Bashforth time advancement algorithm and obtained essentially the same results.Tofind the effect of thermal expansion,wefirst conduct simulations for an isochoricfluid,∆v f=0,then for an expandingfluid with∆v f=−s0.To test the influence of the simulation reference frame,we consider three velocities in the unburned gas:v u=−s0,v u=0,and v u=+s0.If theflame speed were not affected by thermal expansion,then∆v f=−s0would correspond to a density ratio ofα=2, and the background velocity v u=−s0would place the expansion-independentflame stationary in the observer’s frame of reference.The second value,v u=0,corresponds to the reference frame with stationary reactant,andfinally,v u=s0,corresponds to the frame with stationary product.Of course,if theflame speed is influenced by thermal expansion,then theflame,reactant,and product will not remain stationary in the respective reference frames.0 1 23 1 2 48 16 32s / s ob top-hatsolid: ∆v f = 0; dashed: ∆v f = s o 0 12 3 1 2 4 8 16 32s / s ob KPPsolid: ∆v f = 0; dashed: ∆v f = s o Figure 1.Dependence of the travelling wave speed on resolution and simulationreference frame.Reaction rates:top-hat,left;KPP,right.Simulation reference frame:v u =−s 0,squares;v u =0,circles;v u =s 0,triangles.Solid linecorresponds to isochoric case (∆v f =0)and dashed line corresponds to variable-density case (∆v f =−s 0).0.00.20.40.60.81.01.20 1 2 34 5 6s / s o - ∆v f / s o Figure 2.The travelling wave speed as function of expansion parameter ∆v f .Reaction rate:KPP,circles;top-hat,squares.The dashed line shows theapproximation with quadratic function,s/s 0=1−k 1(−∆v f /s 0)+k 2(−∆v f /s 0)2,where k 1=0.2982and k 2=0.0156.The dotted line shows the linearapproximation,s/s 0=1−0.3(−∆v f /s 0).Simulations were performed in thereference frame of the unburned fluid,v u =0,at resolution b =32.The flame speed,s ,measured for the isochoric and variable-density cases,is shown in Fig.1.As resolution increases,the flame speed for the KPP reaction rate converges to s =s 0for both cases.This confirms the flame speed is independent of the expansion parameter ∆v f ,for the KPP rate.For the top-hat reaction rate,the flame speed converges to s =s 0in the isochoric case.However,the variable-density flame speed converges to s =0.72s 0,independent of the reference frame.Next we quantify the difference between the isochoric and variable-density flame speeds as a function of the expansion parameter.We have measured flame speeds for several different different values of ∆v f at high resolution.The results for both top-hat and KPP reaction rates are shown inFig.2.As expected,theflame speed for the KPP rate does not depend on∆v f.Forthe top-hat reaction rate and small jump∆v f,theflame speed can be approximatedby a linear function.The expressions,KPP:s=s0,top-hat:s≈s0+0.3∆v f,(14) summarize our analytical and numerical study of the isolated ARD equation forvelocity profiles which account for thermal expansion.Advection against theflame(v u=−s0)at low resolutions is challenging for the numerical scheme for both KPP and top-hat reaction rates,but especially forKPP.We observe that oscillations precede the front and begin to burn,increasing the effectiveflame speed.It can be shown that without the reaction term,discretizing theadvection term with central differences implies a limit on the cell Reynolds number|v|∆x/κ<1/2,the violation of which results in an oscillatory solution[15].The derivation in[15]is for the advection-diffusion equation,discretized with second-ordercentral differences,and the value(1/2)of the limit is specific to that discretization.Nevertheless,we noticed a strong correlation between resolution and velocity and the appearance of oscillations in theflame front,with corresponding errors in theflame speed.For the ARD equation,the above cell Reynolds number constraint for theadvection-diffusion equation can be expressed in terms of the number of grid pointsper interface.Note that we use fourth-order differences,so these are just estimates. We obtain b≥8|v|/s0for the KPP reaction rate,and b≥2|v|/s0for the top-hat reaction rate.The coefficient in front of|v|/s0depends on reaction rate because of our definition of theflame front resolution,b.Recall that to match theflame thicknesses for the different rates we specified(4),so that at the same resolution,the diffusion coefficient for the KPPflame is one-fourth that for the top-hatflame.One way to avoid the restriction on the cell Reynolds number is to use an upwinddiscretization of the scheme advection terms.In later sections we will show resultsobtained with such a scheme,PPM,and we will see that it delivers much better results for the under-resolved cases.5.Input parameters forflame capturing modelAnalyzing the isolated ARD equation in the previous section,we treated theflame speed as an output of the problem.We wanted to know how s depends on the model parameters:diffusion coefficientκ,reaction timescaleτand the velocity jump∆v f. To use the ARD equation as aflame-capturing model,we want to solve the inverse problem.We want to specify s as an input and compute the corresponding model parameters;if the model behaves correctly,then the observedflame speedˆs in our simulations will be the same as the inputflame speed s.The parameters for theflame capturing model can be calibrated using(14),which expresses the dependence of s on∆v f.Recall that in the full system,the velocity jump is due to thermal expansion and is directly related to the the density ratio. Substituting∆v f=−(α−1)s in(14)and solving for theflame speed,we obtain s=s0/a,whereKPP:a=1,top-hat:a=a(α)≈1+0.3(α−1).Thus,we express theflame speed in terms of density ratioα,a more accessible quantity than the velocity jump across the interface.Next,using the definitions(6)we obtain the diffusion coefficient and the reaction time,κ=asδ0,τ=δ0/(as).(15) The length scaleδ0is related to the isochoricflame thickness as in(4).The variable-densityflame thickness is usually larger than the isochoricflame thickness.(We could calibrate the parameters to match theflame thickness,as well as the speed,but have not done so.)This section concludes our modifications to the ARDflame capturing model.In comparison to the original ARD model,we have added a calibration factor to the mapping of s andδ0toκandτ.This factor accounts for the effect thermal expansion on theflame speed.We have empirically determined the dependence of s on the density change across theflame for the top-hat rate(Fig.(2),)and the corresponding calibration factor,valid for small density jumps.We have also analytically and numerically demonstrated that for the KPP reaction rate,the calibration is not needed because theflame speed is insensitive to thermal expansion.In the next section we will demonstrate that with our calibration,theflame-capturing model with the top-hat rate is effective.6.Verification of the modelThe results above were obtained with a“prototype”code,which solves the isolated ARD equation for a prescribed velocityfield.To verify the coupling with the compressibleflow equations,we implemented the ARDflame capturing model in the FLASH code[4,2],a multidimensional,multiphysics,block-structured AMR code primarily intended for astrophysical applications.The FLASH code solves the system(7)using timestep splitting.The piecewise parabolic method(PPM)advances the solution in time accounting for the convective terms[3],and directional splitting is used whenever multiple spatial dimensions are considered[14].Then a second step is taken for the diffusion and reaction terms;these operators are treated in an unsplit(in time)fashion and advanced using thefirst-order explicit Euler method.Second-order central differences are used for the diffusion term.The ARDflame capturing model was implemented and tested in1-,2-,and 3-D Cartesian,2-D cylindrical,and3-D spherical coordinates.The FLASH code is a structured AMR code,but theflame-capturing model was implemented assuming the ARDflame is always discretized at thefinest refinement level.In the tests we performed,derefining the grid outside of theflame region did not directly affect the performance of theflame-capturing model.Several equation of state(EOS)models are implemented in FLASH.Here we show the results obtained using the gamma-law EOS;we have performed similar tests with the Helmholtz EOS(commonly used for degenerate stellar interiors)and did notfind any unexpected differences.6.1.Planarflame:test of conceptThis section contains a set of one-dimensional tests of the ARDflame capturing model in Cartesian coordinates.The goal is to verify that theflame model still performs its function,i.e.propagates theflame at the desired speed,when coupled to the Euler121 2 481632s / s obtop-hat non-adjustedsolid: α = 1; dashed: α = 20 1212481632s / s obKPP non-adjustedsolid: α = 1; dashed: α = 2Figure 3.Dependence of the travelling wave speed on resolution for top-hat (left)and KPP (right)reaction rates and different advection velocities v u =−s 0(squares),v u =0(circles)and v u =s 0(triangles).Solid lines correspond to isochoric case (α=1)and dashed lines correspond to variable-density case (α=2).The results were obtained without adjustment for compressibility effects (a =1.0).0 1212481632s / s obtop-hat adjustedα = 2Figure 4.Travelling wave speed for top-hate reaction rate shown in Fig.3,computed with adjustment for compressibility effects (a =1.3).equations.The physical conditions are chosen to match the simulations discussed in Sec.(5),in which the ARD equation (1)was solved in isolation.Given the unburned state and the flame speed,we can control the density ratio αby choosing the heat release q .If q =0,then α=1,and the ARD equation is decoupled from the Euler equations in (7).In this case,the only difference between system (1)and system (7)is the difference in the numerical method,i.e.between central differences and PPM advection schemes.Choosing the heat release so that α=2is equivalent to setting ∆v f =−s 0in (12).Recall that when q =0,(12)is an approximation which relies on several physical。
化工专业英语词汇reaction kinetics 反应动力学reactant 反应物purify 精制提纯recycle 循环回收unconverted reactant未转化的反应物chemical reactortransfer of heat,evaporation,crystallization结晶drying干燥screening筛选,浮选chemical reaction化学反应cracking of petroleum石油裂解catalyst催化剂,reaction zone反应区conservation of mass and energy能量与质量守衡定律technical advance 技术进步efficiency improvement 效率提高reaction 反应separation 分离heat exchange 热交换reactive distillation 反应精馏capital expenditure 基建投资setup 装置capital outlay 费用,成本,基建投资yield 产率,收率reaction byproduct 反应副产物equilibrium constant 平衡常数waste 废物feedstock 进料,原料product 产物,产品percent conversion百分比转化率ether 乙醚gasoline汽油oxygenate content 氧含量catalyst 催化剂reactant 反应物inert 惰性物,不参加反应的物质reactive distillation 反应精馏energy saving 节约能量energy efficiency 能量效率heat-sensitive material 热敏性物质pharmaceutical 制药foodstuff 食品gas diffusivity气体扩散性,气体扩散系数gas adsorption 吸收;absorption:吸附specialty chemical特殊化学品,特种化学品batch间歇的;continuous:连续的micro-reactor 微型反应器hydrogen and methane oxidation 氢气和甲烷氧化反应ethylene epoxidation 乙烯环氧化反应phosgene synthesis 光气合成.commercial proportions 商业规模replication 复制sensor 传感器,探头separation of solids 固体分离suspension 悬浮液porous medium 多孔介质filtration 过滤medium 介质filter 过滤器trap 收集,捕集Buchner funnel 布氏漏斗Vacuum 真空conical funnel 锥形漏斗filter paper 滤纸area 面积filter cake 滤饼factor 因数,因子,系数,比例viscosity 黏度density 密度corrosive property 腐蚀性particle size 颗粒尺寸shape 形状size distribution 粒度分布packing characteristics填充性质concentration 浓度filtrate 滤液feed liquor 进料液pretreatment 预处理latent heat 潜热resistance 阻力surface layer 表面层filtering medium 过滤介质drop in pressure 压降filtering surface 过滤表面filter cake 滤饼cake filtration 饼层过滤deep bed filtration 深层过滤depth 深度law 定律net flow 净流量conduction 传导convection 对流radiation 辐射temperature gradient 温度梯度metallic solid 金属固体thermal conduction 热传导motion of unbound electrons 自由电子的运动electrical conductivity 导电性thermal conductivity 导热性poor conductor of electricity 不良导电体transport of momentum 动量传递the random motion of molecules 分子无规则运动brick wall 墙壁furnace 火炉,燃烧器metal wall of a tube 金属管壁macroscopic particle 宏观的粒子control volume 控制体enthalpy 焓macroscopic phenomenon 宏观现象forces of friction 摩擦力fluid mechanics 流体力学flux(通量,流通量)of enthalpy 焓通量eddy 尾流,涡流turbulent flow 湍流natural and forced convection 自然对流和强制对流buoyancy force 浮力temperature gradient 温度梯度electromagnetic wave 电磁波fused quartz 熔化的石英reflect 反射,inflection:折射matte无光泽的,无光的temperature level 温度高低inter-phase mass transfer界相际间质量传递rate of diffusion扩散速率acetone 丙酮dissolve 溶解ammonia 氨ammonia-air mixture 氨气-水混合物physical process 物理过程oxides of nitrogen 氮氧化物nitric acid 硝酸carbon dioxide 二氧化碳sodium hydroxide 氢氧化钠actualrate of absorption 实际吸收速率two-film theory 双膜理论concentration difference 浓度差in the vicinity of 在…附近,靠近..,大约…,在…左右molecular diffusion 分子扩散laminar sub-layer 层流底层resistance 阻力,阻止boundary layer 边界层Fick’s Law费克定律is proportional to 与…成比例concentration gradient 浓度梯度plate tower 板式塔installation 装置feed 进料bottom 底部,塔底solvent 溶剂top 顶部,塔顶partial vaporization 部分汽化boiling point 沸点equimolecular counter-diffusion 等分子反向扩散ideal system 理想系统ratio of A to B A与B的比值with the result that:由于的缘故,鉴于的结果tray 塔板packed tower 填料塔bubble-cap tower 泡罩塔spray chamber 喷淋室maintenance expense 维修费foundation 基础tower shell 塔体packing material 填料pump 泵blower 风机accessory heater 附属加热器cooler 冷却器heat exchanger 换热器solvent-recovery system 溶剂回收系统operating cost 操作费用power 动力circulating gas 循环气labor 劳动力steam蒸汽regenerate再生cooling water 冷却水solvent make-up 补充溶剂optimum 最优的unabsorbed component未吸收组分purity纯度volatility挥发性vapor pressure蒸汽压liquid mixture 液体混合物condense凝缩,冷凝binary distillation双组分精馏multi-component distillation多组分精馏stage-type distillation column级板式精馏塔mount 安装,固定conduit导流管),downcomer 降液管gravity重力weir溢流堰vapor-liquid contacting device汽液接触装置valve tray浮阀塔板reboiler再沸器vaporization汽化condensate冷凝液,凝缩液overhead vapor塔顶汽体condenser冷凝器ifeed tray进料板base塔底,基础bottoms product塔底产品condensation冷凝stripping section汽提段,提馏段distillate section精馏段total condense全凝器distillate product塔顶馏出产品reflux回流thermodynamic equilibrium 热力学平衡solution溶液fractional crystallization分步结晶solubility,溶解度,溶解性soluble可溶解的solvent溶剂employ采纳,利用miscible可混合的,可溶的,可搅拌的mechanical separation 机械分离)liquid-liquid extraction 液液萃取aromatic 芳香烃的paraffin石蜡,链烷烃lubricating oil润滑油decompose分解,离解,还原,腐烂penicillin青霉素streptomycin(链霉素)precipitation沉淀,沉析ethyl alcohol乙醇)extract萃取液heat requirement热负荷solute溶质extract phase萃取相baffle-plate折流挡板,缓冲挡板settling tank沉降槽centrifuge离心.离心机,离心分离emulsifying agent乳化剂density difference密度差raffinate萃余液extract 萃取液drying of Solids 固体干燥process material过程物料(相对最终产品而言的) organic有机的,有机物的benzene苯humidity湿度moisture content湿含量drying rate干燥速率critical moisture content临界湿湿含量falling-rate降速concave (凸的,凸面)or convex(凹的,凹面)approximate to:接近,趋近straight line:直线constant-rate drying period恒速干燥阶段convection drying对流干燥drying gas干燥气体falling-rate period降速干燥阶段mean value平均值vacuum drying真空干燥discolor变色,脱色sublime升华freeze drying冷冻干燥adiabatic绝热的,不传热的pressure gradientperpendicular to:与----垂直counter-current逆流per unit area单位面积water-cooling tower水冷塔sensible heat(sensible heat:显热)water droplet水珠,水滴quantitative relation定量关系thermal diffusion热扩散at right angles to 与…成直角,与…垂直by virtue of 由于,根据,凭借于molecular transfer分子传递balance 抵消,平衡drag forces曳力a function of …的函数of the same order具有同一数量级eddy diffusion涡流扩散is almost inversely proportional to 几乎与…成反比Reynolds number雷诺准数fully developed turbulent flow充分发展湍流coefficient系数In principle从原理而言exothermic(放热的,endothermic吸热的,adiabatic绝热的)triple bond三健,三价nitrogen oxides氮氧化物compound化合物conversion转化,转化率protein蛋白质compress压缩reaction yield反应产率reaction speed反应速度one-pass(单程) reactorenergy input能量输入maximum最大的near toequilibrium接近平衡output产出,输出,产量fertilizer化肥urea尿素ammonium nitrate硝酸铵ammonium phosphate磷酸铵ammonium sulfate硫酸铵diammonium hydrogen phosphate磷酸二氢铵 ash纯碱pyridine砒啶polymers聚合物nylon尼龙acrylics丙烯酸树脂via经,由,通过,借助于hydrogen cyanide氰化氢nitric acid硝酸bulk explosive集装炸药crude oil原油natural gas天然气bitumen沥青fossil fuel化石燃料seepage渗出物asphalt沥青oil drilling采油gasoline汽油paint涂料plastic塑料synthetic rubber合成橡胶fiber纤维soap肥皂cleansing agent清洗剂wax石蜡explosive炸药oil shale油页岩deposit沉积物aquatic plant 水生植物sedimentary rock沉积岩sandstone砂岩siltstone泥岩tar sand沥青石chain-shaped链状的methane甲烷paraffin石蜡,烷烃ring-shaped(环状的)hydrocarbon naphthene环烷烃naphtha石脑油tarry柏油的,焦油的,焦油状的asphaltene沥青油impurity杂质pollutant 污染物combustion燃烧capillarity毛细现象,毛细管力viscous resistance粘性阻力barrel桶(国际原油计量单位)tanker油轮kerosene煤油heavy gas oil重瓦斯油reforming重整cracking裂化octane number of gasoline汽油辛烷值branched-chain(带支链的)materials science材料科学mechanical, thermal, chemical, electric, magnetic, and optical behavior. (机械性能、热学性能、化学性能、电学性能、磁性能、光学性能)Amalgam 汞齐,水银;混合物,交叉solid state physics固体物理学metallurgy 冶金学,冶金术magnet 磁铁,有吸引力的人或物insulation 绝缘catalytic cracking 催化裂化structural steels 结构钢computer microchip 计算机芯片Aerospace 航空Telecommunication 电信information processing 信息处理nuclear power 核能energy conversion 能量转化internal structure 内部结构defect structure 结构缺陷crystal flaw 晶体瑕疵vacant atomic site 原子空位dislocation 错位precipitate 沉淀物semiconductor 半导体mechanical disturbance 机械扰动ductility 延展性brittleness 脆性spinning electrons 旋转电子amorphous 非定型的,非晶型的,非结晶的,玻璃状的;无一定目的的,乱七八糟chemical process safety 化工过程安全exotic chemistry 奇异化学hydrodynamic model水力学模型two-phase flow两相流dispersion model分散模型toxic有毒的release释放,排放probability of failure失效概率accident prevention事故预防hard hat 安全帽safety shoe防护鞋rules and regulations 规章制度loss prevention损失预防hazard identification 危害辩识,technical evaluation技术评估safety management support安全管理基础知识safety experience安全经验technical competence技术能力safety knowledge安全知识design engineer设计师cost engineer造价师process engineering过程工程plant layout工厂布局general service facilities公用工程plant location工厂选址close teamwork紧密的团队协作specialized group专业组storage仓库waste disposal废物处理terminology术语,词汇accountant会计师,会计,出纳final-proposal决议tangible return有形回报Empirical model 经验模型process control(过程控制)first-principles基本原理,基本规则regression model回归模型.operating condition操作条件nonlinear-equation-solving technique非线性方程求解技术process-simulation software packages过程模拟软件包least-squares-regression最小二乘法statistical technique 统计技术intensity强度,程度phenomenological model 现象模型model identification模式识别neural network神经网络a priori:先验的,既定的,不根据经验的,由原因推出结果的,演绎的,直觉的process data historian:过程数据历史编撰师qualitative定性的quantitative precision定量的精确high-fidelity高保真的computationally intensive计算量大的mathematical expressionsteady-state model稳态模型bioengineering生物工程artificial人工的hearing aid助听器artificial limb假肢supportive or substitute organ辅助或替代器官biosynthesis生物合成life scientist生命科学家agricultural engineer农艺师fermentation发酵civil engineer土木工程师sanitation卫生physiologists生理学criteria 指标human medicine人体医学medical electronics医疗电子medical instrumentation医疗器械blood-flow dynamics血液流动动力学prosthetics假肢器官学biomechanics生物力学surgeon外科医生replacement organ器官移植physiologist生理学家counterpart对应物,配对物psychology心理学self-taught自学barrier障碍物medical engineering医学工程,医疗工程health care保健diagnostic application of computers计算机诊断agricultural engineering农业工程biological production生物制品生产bionics(仿生学)human-factors engineering人类与环境工程environmental health engineering环境健康工程environmentally benign processing环境友好加工commodity or specialty通用商品或特殊化学品styrene苯乙烯ibuprofen异丁苯丙酸the Chemical Manufacturers Association化工生产协会as a whole整体而言emission释放物,排放物voluntary自愿的,无偿的,义务的;有意的,随意的;民办的in the absence of无---存在deactivate失活bulk chemical 大宗化工产品Fine chemical 精细化工Pharmaceutical制药segment段,片,区间,部门,部分;弓形,圆缺;分割,切断tonnage吨位,吨数,吨产量inorganic salt无机盐hydroquinone 对苯二酚demonstrate论证,证明,证实;说明,表明,显示forefront最前线,最前沿Lewis acid不可再生的路易斯酸anhydrous无水的phaseout消除HF alkylation氰氟酸烷基化catalytic oxidation催化氧化governmental regulation政府规定pharmaceutical intermediate药物中间体stereoselective立体选择性的ketone酮functional group官能团detrimental有害的chlorofluorocarbon二氯二氟化碳,氟里昂carbon tetrachloride四氯化碳straightforward简单明了的coordinating ligand配合体,向心配合体kilogram千克thermal stability热稳定性devastate破坏,蹂躏outline描绘,勾勒membrane technology膜技术production line生产线dairy牛奶water purification水净化lifetime寿命membrane module膜组件durability 耐久性,寿命,使用期限,强度chemical additive添加剂end-of-pipe solution 最终方案closed system封闭系统substitute取代,替代technical challenge技术挑战,技术困难wastewater treatment污水处理fouling污垢,发泡surface treatment表面处理applied Chemistry应用化学nomenclature of chemical compound化学化合物的命名法descriptive 描述性的prefix前缀alkane烷烃family族carbon skeleton碳骨架chain链Latin or Greek stem 拉丁或者希腊词根suffix后缀constitute取代物,取代基homologous series同系物branched chain支链烷烃parent母链,主链derivative衍生物substituent取代基locant位次,位标replicating prefix重复前缀词Gas and Liquid Chromatography气相色谱与液相色谱analytical chemistry分析化学moving gas stream移动的气流heats of solution and vaporization溶解热和汽化热activity coefficient活度系数counteract抵消milliliter毫升essential oil香精油test mixture测试混合物sample样品helium氦argon氩carrier载体injection注射stationary nonvolatile phase静止的不挥发相detector检测器fraction collector馏分收集器columnar liquid chromatography柱状液相色谱仪retention volume保留体积retention times保留时间high-performance高性能mobile phase移动相high-efficiency高效的analyte分析物plane chromatography薄层色谱capillary action毛细管作用assay分析化验fluorescence 荧光色,荧光retardation factor保留因子,延迟因子。
Determination of the chemical diffusion coef ficient of lithium in Li 3V 2(PO 4)3Anping Tang a ,b ,⁎,Xianyou Wang b ,Guorong Xu a ,Zhihua Zhou a ,Huidong Nie aa School of Chemistry and Chemical Engineering,Hunan University of Science and Technology,Hunan 411201,China bSchool of Chemistry,Xiangtan University,Hunan 411105,Chinaa b s t r a c ta r t i c l e i n f o Article history:Received 11February 2009Accepted 22March 2009Available online 5April 2009Keywords:Diffusion KineticsChemical diffusion coef ficient Li 3V 2(PO 4)3CV EISThe chemical diffusion of lithium ion in Li 3V 2(PO 4)3were investigated by cyclic voltammetry (CV)and electrochemical impedance spectroscopy (EIS)methods.The CV results show that there exists a linear relationship between the peak current (i p )and the square root of the scan rate (ν1/2).The impedance spectrum exhibits a single semicircle and a straight line in a very low frequency region.A linear behavior was observed for every curve of the real resistance as a function of the inverse square root of the angular frequency in a very low frequency region.The obtained chemical diffusion coef ficient from EIS measurements varies within 10−9to 10−8cm 2·s −1,in good agreement with those from CV results.Crown Copyright ©2009Published by Elsevier B.V.All rights reserved.1.IntroductionFramework materials based on the phosphate polyanion are being considered as favorable replacements for lithium metal oxides as the positive electrodes in lithium ion battery applications.In addition to possessing high redox potentials and good lithium transport,these materials display remarkable electrochemical and thermal stability in comparison with lithium metal oxides.Among the above mentioned phosphates,monoclinic Li 3V 2(PO 4)3has shown considerable promise due to its high theoretical capacity of 198mAh g −1.Many researchers have focused on improving the cycle stability of Li 3V 2(PO 4)3by coating with carbon [1–3]or doping with alien ions [4,5]and probing the global structure of the material by neutron and X-ray diffraction (XRD)techniques [6–8]or infrared and Raman spectroscopy [9].Lithium diffusion in the electrodes is a key factor that determines the rate at which a battery can be charged and discharged.With increasing interest in high power density,the kinetics of Li diffusion becomes more important.To our knowledge,there are few reports about the chemical diffusion of lithium ion in Li 3V 2(PO 4)3.We have reported the electrochemical properties of Li 3V 2(PO 4)3/C composite,which was synthesized by solution method [10].The goal of the present work is an investigation of the chemical diffusion of lithium ion in Li 3V 2(PO 4)3using CV and EIS.2.ExperimentalThe solution route proceeded as follows:stoichiometric V 2O 5was added to the solution which contained the H 3PO 4and an appropriate amount of sucrose with continued stirring at about 80°C until a clear blue solution formed.Stoichiometric LiOH was added to the above solution,and finally the resultant solution was heated to dryness.The precursors were ground for 30min,pressed into pellets,and then sintered at 700°C for 3h in a tubular furnace with flowing argon gas to yield the Li 3V 2(PO 4)3/C composite.The Li 3V 2(PO 4)3electrodes were fabricated from a total of 15%carbon,which consisted of the residual carbon in a composite and acetylene black added to an electrode,5%polyvinylidene fluoride binder and 80%active material.The electrolyte consisted of 1M LiPF 6solution in a mixture of ethylene carbonate and dimethyl carbonate with a volumetric ratio of 1:1.CV was performed at 25°C with a CHI 660electrochemical instrument in the range of 3.0–4.5V vs Li +/Li.EIS measurements were performed at 25°C using a CHI 660electrochemical instrument in the frequency range of 10kHz –10mHz with an AC voltage of 5mV.3.Results and discussionThe CV diagrams for the Li 3V 2(PO 4)3electrode,recorded at scan rates of 0.1,0.2,0.5and 0.8mV·s −1,are shown in Fig.1.Four observations can be obtained from CV pro files with different scan rates.Firstly,the potential difference (ΔE p )between the anodic and corresponding cathodic peaks increases with increasing scan rate.This observation was also reported in the LiFePO 4system by other researchers [11].Secondly,for scan rates of less than 0.2mV·s −1,three oxidation peaks can be seen from every CV pro file.The twoMaterials Letters 63(2009)1439–1441⁎Corresponding author.School of Chemistry and Chemical Engineering,Hunan University of Science and Technology,Hunan 411201,China.Tel.:+867328290045;fax:+867328290509.E-mail address:t-ap@ (A.Tang).0167-577X/$–see front matter.Crown Copyright ©2009Published by Elsevier B.V.All rights reserved.doi:10.1016/j.matlet.2009.03.035Contents lists available at ScienceDirectMaterials Lettersj o u r na l ho m e p a g e :w w w.e l s ev i e r.c o m /l o c a t e /m a t l e tpeaks at lower potentials correspond to the first lithium ion extraction from Li 3V 2(PO 4)3structure,indicating that the first lithium is removed in two steps,and the third peak more than 4.1V originates from the removal of the second lithium ion.All the three peaks are associated with V 4+/V 3+redox couple.It is obvious that the second lithium ion is more stable than the first one in the Li 3V 2(PO 4)3host structure.When the scan rate is more than 0.2mV·s −1,however,only two oxidation peaks are observed from every CV pro file.Thirdly,the lithium insertion process displays three reduction peaks,regardless of the scan rate.Finally,for all scan rates,the oxidation peak more than 4.1V and the corresponding reduction peak both show a highest peak current,respectively.In theory,the anodic and cathodic peak currents have the same magnitude,i.e.,|i pc /i pa |=1(no side reaction),which is characteristic of a reversible reaction.However,Fig.1shows that this is not the case for Li 3V 2(PO 4)3.The similar observation was also reported in the LiFePO 4system by other researchers [11].As Li 3V 2(PO 4)3undergoes a series of phase transitions during charge and discharge,Li ions are most likely transported through regions with Li 3V 2(PO 4)3,Li 2.5V 2(PO 4)3,Li 2V 2(PO 4)3or LiV 2(PO 4)3[1,2].This difference in electro-chemical environments for Li movement may account for the difference in the magnitude of the peak current.We thus argue that |I pc /I pa |=1need not be upheld for the Li 3V 2(PO 4)3system.The oxidation peak more than 4.1V and the corresponding reduction peak currents from the steady-state CVs are plotted in Fig.2vs the square root of the scan rates (ν1/2),as expected for diffusion-controlled process.The peak current (i p )shows half-order dependence on scan rate,consistent with semi-in finite diffusion control,for the entire range of scan rates.From the slope of I p vs ν1/2,the diffusion coef ficients of lithium ion have been estimated,according to semi-in finite lithium diffusion and the molar volume ofLi 3-x V 2(PO 4)3(x =2).The anodic and cathodic diffusion coef ficients of lithium ion are 2.69×10−8and 2.68×10−8cm 2·s −1,respectively.Fig.3shows a sequence of Niquist plots obtained under various open-circuit condition.Prior to the EIS testing,the electrodes were cycled galvanostatically for 5cycles between 3.0–4.3V to ensure the stable SEI films formation and percolation of the electrolyte through electrode particles.As shown in Fig.3,the semicircles have a high-frequency intercept on the Z ′that represents the solution resistance,which consists of the resistance of the electrolyte and an electrode.At lower frequencies,the resistance related to the charge transfer between the electrolyte and the active material can be identi fied.A very low frequency region of the straight line is attributed to the diffusion of the lithium ions into the bulk of the electrode material or the so-called Warburg diffusion.The diffusion coef ficients of lithiumion,˜DLi ,can be obtained from an analysis of the Warburg impedance,Z W ,which is expressed in the complex plane as [12]:Z w =σ1−j ðÞ1ffiffiffiffiωp ð1Þσ=V m dEdx ÀÁffiffiffiffiffiffiffiffiffiffiffi2nFA p ffiffiffi˜Dq ð2Þwhere σis the Warburg coef ficient,V m is the molar volume of the hoststructure,d E /d x is the slope of the coulometric titration curve vs mobile ion concentration x at each x value,F the Faraday constant,A is the active area taken as the contact area between electrode and electrolyte,and n is the valence of the diffusing species.TheWarburgFig.1.CV pro files of Li 3V 2(PO 4)3electrodes with different scan rates at 25°C.Fig.2.Graph of peak current vs square root of the scanrate.Fig.3.Niquist plots of Li 3-x V 2(PO 4)3measured under various open-circuitvoltages.Fig.4.The plots of the real resistance as a function of the inverse square root of angular frequency at very low frequency region of Li 3-x V 2(PO 4)3.Data obtained from Fig.4.1440 A.Tang et al./Materials Letters 63(2009)1439–1441coefficientσcan be obtained from the slope of the real resistance(Z′) versus the inverse square root of the angular frequency(ω−1/2).Fig.4shows the plots of Z′determined by EIS as a function ofω−1/2in a very low frequency region.A linear behavior was observed for every curve.The diffusion coefficients of lithium ion under various open-circuit conditions are reported in Table1.As demonstrated in Table1,the D Li obtained from EIS varies from10−9to10−8cm2·s−1,consistent with those measured by CV.The magnitude of the D Li is much higher than that in LiFePO4measured by Prosini et al.(2.2×10−16to1.8×10−14cm2·s−1) [13]and Franger et al.(10−14to10−13cm2·s−1)[14],and close to that in ε-VOPO4measured by Song et al.(3.9×−10to4.6×10−9cm2·s−1)[15].4.ConclusionsCV and EIS were used to evaluate the chemical diffusion of lithium in Li3V2(PO4)3.The anodic and cathodic lithium diffusion coefficients determined from CV are 2.69×10−8and 2.68×10−8cm2·s−1, respectively.The chemical diffusion coefficient(D Li)value obtained from EIS measurements is in the range of10−9to10−8cm2·s−1, consistent with those measured by CV.References[1]Saidi MY,Barker J,Huang H,Swoyer JL,Adamson G.J Power Sources2003;19–121:266–72.[2]Saidi MY,Barker J,Huang H,Adamson G.Electrochem Solid State Lett2002;5(7):A149–51.[3]Huang H,Yin SC,Kerr T,Taylor N,Nazar LF.Adv Mater2004;14:1525–7.[4]Barker J,Gover RKB,Burns P,Bryan A.J Electrochem Soc2007;154(4):A307–13.[5]Ren MM,Zhou Z,Li YZ,Gao XP,Yan J.J Power Sources2006;162(2):1357–62.[6]Gaubicher J,Wurm C,Goward G,Masquelier C,Nazar LF.Chem Mater2000;12(11):3240–2.[7]Morcrette M,Leriche JB,Patoux S,Wurm C,Masquelier C.Electrochem Solid StateLett2003;6(5):A80–4.[8]Yin SC,Grondey H,Strobel P,Huang H,Nazar LF.J Am Chem Soc2003;125(2):326–7.[9]Christopher MB,Roger F.Solid State Ion2007;177:3445–54.[10]Tang AP,Wang XY,Yang SY.Mater Lett2008;62(21–22):3676–8.[11]Denis YWY,Christopher F,Wolfgang W,Kazunori D,Takao I,Hiroshi K,et al.J Electrochem Soc2007;154(4):A253–7.[12]Kaoru D,Mohamed M,Minoru U,Isamu U.J Electrochem Soc2003;150(4):A425–9.[13]Prosini PP,Lisi M,Zane D,Pasquali M.Solid State Ion2002;148(1–2):45–51.[14]Franger S,Cras FL,Bourbon C,Rouault H.Electrochem Solid State Lett2002;5(10):A231–3.[15]Song YN,Peter YZ,Stanley WM.J Electrochem Soc2005;152(4):A721–8.Table1The data of the lithium diffusion coefficients in Li3-x V2(PO4)3from EIS.OCV/V 3.43 3.58 3.66 3.81 4.08D/cm2·s−1 3.49×10−87.74×10−8 6.72×10−8 2.56×10−8 1.31×10−91441A.Tang et al./Materials Letters63(2009)1439–1441。
英文原版教材班“材料科学与工程基础”考试试题Examination problems of the course of “fundament of materials science”(注:第1、2、3、5题为必做题;第4、6、7题为选择题,必须二选一。
共100分)姓名:班级:记分:1. Glossary (2 points for each)1) crystal structure:2) basis (or motif):3) packing fractor:4) slip system:5) critical size:6) homogeneous nucleation:7) coherent precipitate:8) precipitation hardening:9) diffusion coefficient:10) uphill diffusion:2. Determine the indices for the planes in the cubic unit cell shown in Figure 1. (5 points)Fig. 13. Determine the crystal structure for the following: (a) a metal with a0 =4.9489 Å, r = 1.75 Å and one atom per lattice point; (b) a metal with a0 = 0.42906 nm, r = 0.1858 nm and one atom per lattice point. (10 points)4-1. What is the characteristic of brinell hardness test, rockwell hardness test and V ickers hardness test? What are the effects of strain rate and temperature on the mechanical properties of metallic materials? (15 points)4-2. What are the effects of cold-work on metallic materials? How to eliminate those effects? And what is micro-mechanism for the eliminating cold-work effects? (15 points)5-1. Based on the Pb-Sn-Bi ternary diagram as shown in Fig. 2, try to(1)Show the vertical section of 40wt.%Sn; (4 points)(2) Describe the solidification process of the alloy 2# with very low cooling speed (includingphase and microstructure changes); (4 points) (3)Plot the isothermal section at 150o C. (7 points)5-2. A 1mm sheet of FCC iron is used to contain N 2 in a heated exchanger at 1200oC. The concentration of N at one surface is 0.04 atomic percent and the concentration at the secondsurface is 0.005 atomic percent. At 1000 oC, if same N concentration is demanded at the secondsurface and the flux of N becomes to half of that at 1200oC, then what is the thickness of sheet? (15 points)6-1. Supposed that a certain liquid metal is undercooled until homogeneous nucleation occurs. (15 points)(1) How to calculate the critical radius of the nucleus required? Please give the deductionprocess.(2) For the Metal Ni, the Freezing Temperature is 1453︒C, the Latent Heat of Fusion is 2756J/cm 3, and the Solid-liquid Interfacial Energy is 255⨯10-7 J/cm 2. Please calculate the critical radius at 1353︒C. (Assume that the liquid Ni is not solidified.)6-2. Fig.3 is a portion of the Mg-Al phase diagram. (15 points)(1) If the solidification is too rapid, please describe the solidification process of Mg-10wt%Alalloy.(2) Please describe the equilibrium solidification process of Mg-20wt%Al alloy, and calculate theamount of each phase at 300︒C.Fig. 3Fig. 27-1. Figure 4 shows us the Al-Cu binary diagram and some microstructures found in a cooling process for an Al-4%Cu alloy. Please answer following questions according to this figure. (20 points)Fig. 4(1)What are precipitate, matrix and microconstituent? Please point them out in the in the figure and explain.(2)Why is need-like precipitate not good for dispersion strengthening? The typical microstructure shown in the figure is good or not? why?(3)Please tell us how to obtain the ideal microstructure shown in this figure.(4)Can dispersion strengthened materials be used at high temperature? Please give the reasons (comparing with cold working strengthening)7-2. Please answer following questions according to the time-temperature-transformation (TTT) diagram as shown in Fig. 5. (20 points)(1)What steel is this TTT diagram for? And what means P , B, and M in the figure? (2)Why dose the TTT diagram exhibits a ‘C’ shape?(3)Point out what microconstituent will be obtained after austenite is cooled according to the curves I, II, III and IV .(4)What is microstructural difference between the curve I and the curve II? (5)How to obtain the steel with the structure of(a) P+B(b) P+M+A (residual) (c) P+B+M+A (residual)(d) Full tempered martensiteIf you can, please draw the relative cooling curve or the flow chart of heat treatment.Fig. 5III III IVExamination of the course of “fundament of materials science”“材料科学与工程基础”考试试题–英文原版教材班(注:第1、2、3题为必做题;第4、5、6、7题为选择题,必须二选一。
1.型式与一般名词风机ventilator通风机 fan透平鼓风机 turbo-blower透平压缩机 turbo-compressortype离心式 centrifugaltype轴流式 axialtype斜流式 mixed-flowtype 容积式 displaceable-bladetype可调叶片式 adjustable-bladesplit垂直剖分面 vertical水平剖分面 horizontalsplittype单吸式 single-suctiontype双吸式 double-suctiondirection进气口方向 suctiondirection出气口方向 dischargedirection旋转方向 rotatingtype悬臂式 overhang双支撑式center impeller type缸 casing段 section级 stage单级 single-stage多级 multi-stagetype立式 vertical卧式 horizontaltype风机装置Ventilator(blower, compressor) plant 轴系 shaftinginertia转动惯量 rotatorthrust轴向推力 axial平衡 balancebalance静平衡 staticbalance动平衡 dynamic平衡精度precision of balanceofweight去重 removalweight加重 additionof通风机低压离心通风机low pressure centrifugal fan中压离心通风机middle pressure centrifugal fan高压离心通风机high pressure centrifugal fan低压轴流通风机low pressure axial fan高压轴流通风机high pressure axial fannumber机号 fan横流式cross-flow type, transverse-flow-typetype对旋式 counter-rotating子午加速型meridionally accelerated type电动机直联型motor directly driven type皮带传动型belt drive type联轴器传动型drive type with coupling透平鼓风机、压缩机水平剖分型horizontal split type筒型barrel type, vertical split type多轴型multi-shaft with multi-velocity typetype等温型 isothermal内冷式internal cooling type外冷式outer cooling type单级高速single-stage with high speed type管线型pipe line typetype轴流-离心式 axial-centrifugal低压透平压缩机low pressure turbo-compressor中压透平压缩机medium pressure turbo-compressor高压透平压缩机high pressure turbo-compressor超高压透平压缩机super high pressure turbo0compressor 增压器 superchargerblower叶式鼓风机 Enkeblower旋涡式鼓风机 regenerative罗茨鼓风机blower罗茨鼓风机 Roots空冷 aircoolingcooling水冷 water卧式horizontal type, A type立式vertical type, B type2.零部件及条件结构定子 statorbox进气室 suctioncasing蜗壳 volute机壳 casing水平部分机壳horizontally split casing上机壳top half casing下机壳bottom half casingcover端盖 endring卡环 shear支腿 supportdrain排渣孔 inclusionhole测量孔 measuringrod导杆 guide集流器 collector整流罩 cowldiffuser整流体 conicalplate底座 base共用底座common base platevane导流器 prewhirlervane 预旋器 prerotation扩压器 diffuserdiffuser旋转扩压器 rotating转子 rotor挠性转子 flexiblerotorrotor钢性转子 rigid主轴 mainshaft叶轮 impellerdisc轮盖 side轮盘 maindiscboss轮毂 hub进口圈 mouthring导风轮 inducerimpeller闭式叶轮 closed半开式叶轮semi open impellerimpeller开式叶轮 open多叶式叶轮 multi-veinedimpeller 叶片 bladeblade动叶 rotaryblade 静叶 stationary隔块 spacer叶型 blade翼型中线 profileaxis翼弦 profile弦长 chordlength前缘点 chord后缘点leading edge point最大弯度trailing edge pointcamber最大弯度位置 maximum最大厚度maximum camber position最大厚度位置 maximumthickness最大相对厚度maximum thickness positionof leading edge 前缘方向角 directionalangle后缘方向角directional angle of trailing edge 叶型弯曲角bending angle of profile叶型最大厚度maximum thickness of profile进口气流角inflow angle, entry air angle出口气流角discharge angle exit air angle进口几何角inlet geometric angle出口几何角outlet geometric angle叶片安装角blade setting angleangle冲角 attack气流落后角flow lag angle气流折弯角flow deflection angle栅距pitch of cascaderatio相对栅距 pitch-chord叶栅稠度solidity of cascadeheight叶片高度 bladeratio展弦比 aspectfrequency叶片频率 blade叶栅 cascadecascade平面叶栅 planesupport弹性支座 spring隔板 diaphragmduct弯道 bend回流器 return-channel少通道扩压器 straightdiffuser轴齿轮shaft with pinionshaft阶梯轴 stepped节鞭轴circumferentially fluted shaftshaft光轴 plain罗茨鼓风机casing整体机壳 wholeplate墙板 wall前墙板front wall plate后墙板back wall plate主动轴driving shaft, main shaftshaft从动轴 driven齿轮圈 gearrimhub齿轮毂 gear齿轮箱罩gear box cover甩油盘splash lubrication discprofile叶蜂 convexprofile叶谷 concavemesh叶轮啮合 impellerrationdiameter长径比 length容积利用系数coefficient of effective volumeside非工作面 non-workingwidth非工作面宽度 non-working叶轮头数thread numbers of impeller叶轮截面积impeller section areaarea泄露面积 leakage环列叶栅 annularcascadecascade直列叶栅 in-linecascade空间叶栅 space双列叶栅 doublecascadeS1 相对流面S1 relative stream surfaceS2 相对流面S2 relative stream surface等内径equal inside diameter等外径equal outside diametertype混合型 mixing轮毂比boss ratio, hub ration直径比 diametralratio跨距 spanblades前向叶片 forward-curved径向叶片 radial-tippedbladesblades后向叶片 backward-curvedimpeller 三元叶片 three-dimensional圆弧叶片 curvedbladeblade翼型叶片 aerofoilblade平板叶片 plateblade扭曲叶片 twistblade直叶片 straightdisc平衡盘 balance叶轮中间加强环reinforcing ring in the middle of impellerrod叶轮拉杆 tieshaft中间轴 intermediateweight平衡块 balancingsleeve轴套 shaft透平鼓风机、压缩机垂直剖分机壳vertical split casingcasing筒型机壳 barrelcasing前机壳 frontcasing后机壳 backcasing中机壳 middle平衡室balance air compartment平衡气管路balance air pipe linesupport挠性板支座 flexible3.性能performance 气动曲线 aerodynamicparameter性能参数 performance性能曲线 performancecurve无因次性能曲线dimensionless property curve计算性能曲线calculated performance curvecurvecharacteristic管网性能曲线 networkcondition工况 operationgas理想气体 perfectgas实际气体 actualair标准空气 standardcondition标准状态 standardcondition进气条件 suction容积流量volume flow quantity重量流量weight flow quantity质量流量mass flow quantityratio压力比 pressure流量系数capacity coefficient, volume coefficientrise升压 pressurepressure临界压力 criticalpressure临界温度 contrasttemperature对比压力 contrast对比温度polytropic compression process多变压缩过程isentropic compression process等熵压缩过程isothermal compression process等温压缩过程 adiabaticexponentvelocity绝热指数 relativevelocity相对速度 peripheral圆周速度 absolutevelocitytriangle速度三角形 velocity轴向速度 axialvelocityvelocity径向速度 radialvelocity切向速度 tangentialvelocity子午速度 meridionalspeed比转速 specifichead理论能量头 theoretical能量头系数coefficient of head周速系数coefficient of peripheral velocity滑动 slip装置轴功率shaft power of unitperiod运行周期 runningnumber马赫数 Mach临界马赫数critical Mach numbernumber雷诺数 Reynolds临界雷诺数critical Reynolds numbermodeling自动模化 automaticsimilarity几何相似 geometricsimilarity运动相似 movingsimilarity动力相似 dynamicdesign相似设计 similarsimilarity近似设计 approximate特征尺寸 characteristicdimensioneffect尺寸效应 size对数性能曲线log performance curveperformancecurve 选择性能曲线 selected系列综合性能曲线complete characteristic curveschema空气动力略图 aerodynamic通风机静压static pressure of fan通风机动压dynamic pressure of fan通风机全压total pressure of fan有效功率actual power, useful powerpower内功率 innerefficiency内效率 inner静压效率efficiency of static pressure内静压效率efficiency of inner static pressure全压系数efficiency of tatal pressure全压效率coefficient of total pressure功率系数coefficient of power内功率系数coefficient of inner power静压系数coefficient of static pressureorifice等积孔 equivalentdiameter比直径 specificfactor滑动系数 slipdegree反作用度 reactionloss机械损失 mechanical管网损失loss of pipe lines扩压损失loss of diffusionloss冲击损失 impactloss摩擦损失 frictionloss流动损失 flowloss轮阻损失 dragvortex二次涡 secondaryflow潜流 drowned泄漏 leakageleakage内泄漏 internalleakage外泄漏 outer泄漏系数 leakagefactor轮阻系数coefficient of dragefficiency绝热效率 adiabaticefficiency多变效率 polytropicefficiency等温效率 isothermalefficiency机械效率 mechanicalefficiency传动效率 drivespeed风机效率 rotatingspeed转速 loose松动转速 criticalspeedvibration临界转速 bendingvibration弯振 torsionaleffect回转效应 revolvingsurface工作面 pressuresurface非工作面 suction旋转脱离 rotatingstall喘振 surgepoint喘振点 surgelimit喘振界线 surge功率裕度margin of power正常运行点normal operating point罗茨鼓风机efficiency容积效率 volumetric实际流量real flow, actual flow理论流量 theoreticalflow4.装置及附属装置密封迷宫式密封 labyrinthsealseal蜂窝型密封 honeycombseal机械密封 mechanicalseal浮环密封 floating-ringseal抽气密封 air-bleed抽气器 air-bleedset填料密封 packing管网network of pipe lines参考气 referencegas二次平衡气secondary balancing gasset冷却系统 cooling油系统 oilsystem油站oil supply unit高位油箱overhead oil tank压力油箱pressure oil tanksystem防喘振装置 anti-surgemonitor轴位移指示器 axial-displacement消声器 silencer过滤器 filtereliminatormoisture除湿器 dryer,collectoer除尘器 dustparts备件 spare5.运行和试车test试车 running气动性能曲线aerodynamic performance test机械运转实验mechanical running teststand实验台 testing探针 probetunnel风洞 windwindtunnel校正风洞 calibrated整流网格 straigtener试验管路test pipe line并联 parallel串联 series切换 change-overtest模化试验 modelingtest强度试验 strength水压试验hydrostatic pressure testtest破坏试验 destructed工业性运行试验plant running test, full scale running test 超速试验over speed test, spin testtest现场试验 field空载运行unloaded running, idle running test闭式试验装置closed loop system找正 alignment当量转速 equivalentspeedtorque启动力矩 starting盘车 barringtime惰转时间 idleplate孔板 orifice喷嘴 nozzle性能调节 performanceregulatingregulating变转速调节 variable-speed进气节流调节inlet throttle regulating排气节流调节discharge throttle regulating进气预旋调节inlet pre-whirl regulatingregulating转动叶片调节 blade-rotatingregulating等流量调节 flow-equaledregulating等压调节 equipressure旁通调节 by-passregulatingregulating防喘振调节 anti-surgesystem调节系统 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a r X i v :c o n d -m a t /9610059v 3 [c o n d -m a t .s t a t -m e c h ] 9 O c t 1997Reaction-Diffusion Processes from Equivalent Integrable Quantum Chains Malte Henkel a ,Enzo Orlandini b,c and Jaime Santosb a Laboratoire de Physique des Mat´e riaux 1,Universit´e Henri Poincar´e Nancy I,BP 239,F -54506Vandœuvre-l`e s-Nancy Cedex,France ,b Theoretical Physics,Department of Physics,University of Oxford,1Keble Road,Oxford OX13NP,UKc Service de Physique Th´e orique,CEN Saclay,F -91191Gif-sur-Yvette Cedex,France 2Abstract One-dimensional reaction-diffusion systems are mapped through a similarity transformation onto integrable (and a priori non-stochastic)quantum chains.Time-dependent properties of these chemical models can then be found exactly.The reaction-diffusion processes related to free fermion systems with site-independent interactions are classified.The time-dependence of the mean particle density is calculated.Furthermore new integrable stochastic processes related to the Heisenberg XXZ chain are identified and the relaxation times for the particle density and density correlation for these systems are found.PACS:02.50.Ga,05.40.+j,82.20.Mj1IntroductionThe physics of interacting particles out of thermodynamic equilibrium is an intriguing and challenging problem.For important reaction-diffusion processes which display a wide variety of interesting and unexpected phenomena,see[1,2,3,4,5]and references therein.They are not only of experimental importance but also pose a theoretical problem of considerable difficulty as there is no general framework for their treatment,such as detailed balance for equilibrium systems.While the classic approach, involving phenomenological rate equations,is sufficient to the describe the time-dependent behavior of non-equilibrium systems in sufficiently high spatial dimensions,in low dimensions the diffusive mixing is ineffective and new phenomena appear.As an example,consider a system consisting of a single species of particles A undergoing diffusion and subject to the two chemical reactions A+A→A with rate r c and A+A→inert with rate r a.For this system one expects,starting from an initial particle densityρ0,at late times an algebraic decay of the mean particle concentration[6]ρA(t)∼A t−y;t→∞(1.1) In one-dimensional systems,one has y=1group(see e.g.[13]),improved mean-field approaches or exact calculations,see[2]for a collection of reviews.It is the aim of this paper to explore some of the possibilities of obtaining exact results.A convenient starting point for an exact description of a stochastic process is the formulation of the problem in terms of a master equation.The underlying assumption of this approach,viz.the absence of memory effects,is at least approximately true for many real systems.A master equation(see section 2)is afirst order linear differential equation in time for the probability distribution of the stochastic variables describing the ing standard procedures,see[14,16,15,17]it may be conveniently written as a matrix equation and thus its solution is turned into an eigenvalue problem3.The crucial point is that it has been realized in recent years that for many models of interest the matrix appearing in this eigenvalue problem is the quantum Hamiltonian(or the transfer matrix respectively,in the case of discrete time dynamics)of some integrable quantum chain[18,19,20,21,22,23,24,25,26,27,28, 29,30,31,32,33,34].This insight has made available the tool box of integrable models(e.g.Bethe ansatz[35,36,37])for these interacting particle systems far from equilibrium and has led to many new exact results for their dynamical and stationary properties.Clearly,the models tractable by such means are usually rather simple,but the observed universality of many quantities of interest make these models both theoretically and experimentally interesting.Most integrable stochastic models studied so far are directly given in terms of an integrable quantum chain or transfer matrix.In these cases,“just by looking”at the problem one recognizes some known integrable system.However,it has been observed recently that one may obtain from a given stochastic quantum Hamiltonian by a similarity transformation the Hamiltonian of some other stochastic process, see[38,39,10,40].This relates a system which is not obviously integrable to another system which is and in this way exact results may be obtained.At the same time it was also realized that indeed one may obtain by a similarity transformation a stochastic Hamiltonian from some integrable Hamiltonian which does not describe a stochastic process[25,10].This is implicit in many earlier treatments of reaction-diffusion processes,but has not yet been exploited systematically.It shows that many more stochastic systems than previously thought are actually integrable.In this paper,our strategy is as follows.We start from some(a priori non-stochastic)integrable quantum chain H.The examples we shall consider can be analyzed using Bethe ansatz and/or free fermion techniques.Next we perform a similarity transformation and ask under which conditions on the parameters of the original integrable quantum chain H and on the transformation matrix one obtainsa stochastic Hamiltonian.In this way we identify several classes of new integrable stochastic models. Finally,we use the knowledge provided by the integrability to obtain some exact results for these processes,in particular,the average density at time t,and the(longest)relaxation time in the system.Pursuing this program in full generality appears to be a formidable task.Therefore we shall re-strict ourselves to systems which are(a)translationally invariant,(b)involve particles of only one kind with hard core repulsion preventing double occupancy of a single site and(c)which interact only via effective nearest neighbor interaction.We shall make at various points comments on generalizations, e.g.to other boundary conditions,but we shall not work out any details in these cases.Finally,we shall consider only similarity transformations which are translationally invariant and which preserve the locality of all observables.This excludes e.g.sublattice transformations[41]or duality transfor-mations[42,43]which also give rise to transformations between different stochastic Hamiltonians or between non-stochastic and stochastic Hamiltonians.We would like to stress that we shall consider only continous-time dynamics.However,all our results apply also to models with suitably chosen discrete time dynamics.The paper is organized as follows:in section2we review the Hamiltonian formulation for non-equilibrium stochastic systems and its connection with integrable quantum Hamiltonians of magnetic systems.We also specify the similarity transformations which will be used to link stochastic systems with integrable ones and comment briefly on the relationship with continuumfield theory.In section 3,we give the full classification of the stochastic systems which can be reduced to a free fermion Hamiltonian with site-independent interactions.In section4,wefind stochastic systems which have the same spectrum as a XXZ chain with real matrix elements.In section5,we use the link with the free fermion case to calculate explicitly the time-dependent particle density.Section6gives our conclusions. More technical material is relegated to the appendices.In appendix A,we extended the standard technique of Lieb-Schultz-Mattis for the diagonalization of a hermitian free fermion Hamiltonian to the non-hermitian case.Appendix B gives further details for the classification of those stochastic systems similar to a free fermion Hamiltonian.In appendix C we recall the relationship of one of the stochastic systems related to free fermions to the biased voter model.Appendix D gives some further details for the construction of stochastic processes from the XXZ chain.Appendix E describes the details of the caculation of the long-time behaviour of particle densities and two-point correlators from both the Bethe ansatz and the truncated equations of motion.Appendix F recalls the relationship between the Hamiltonian spectra for periodic and free boundary conditions.2Quantum chain formulation of stochastic processesIn this section,we review the reformulation of a non-equilibrium stochastic system defined by some master equation in terms of the spectral properties of an associated quantum Hamiltonian H.To be specific,we only consider systems defined on a chain with L sites and two allowed states per site.We represent the states of the system in terms of spin configurations{σ}={σ1,σ2,...,σL}whereσ=+1corresponds to an empty site andσ=−1corresponds to a site occupied by a single particle.We are interested in the probability distribution function P(σ;t)of the configurations{σ}.Our starting point is the master equation for the P(σ;t)∂t P(σ;t)= τ=σ w(τ→σ)P(τ;t)−w(σ→τ)P(σ;t) (2.1) where w(τ→σ)are the transition rates between the configurations{τ}and{σ}and are assumed to be given from the phenomenology.In order to rewrite this as a matrix problem,we introduce a state vector|P = σP(σ;t)|σ (2.2) and eq.(2.1)becomes∂t|P =−H|P (2.3) where the matrix elements of H are given byσ|H|τ =−w(τ→σ)ifτ=σ, σ|H|σ = τ=σw(σ→τ)(2.4) The operator H describes a stochastic process since all the elements of the columns add up to zero. This conservation of probability,viz. σP(σ;t)=1,is equivalent to the relations|H=0(2.5) where s|= σ σ|is a left eigenvector of H with eigenvalue0.Correspondingly,H has at least one right eigenvector with eigenvalue0.Such a vector does not evolve in time and therefore corresponds to a steady state distribution of the system.Since in general H is not symmetric,this steady state vector may be highly non-trivial.Note that all this is completely general and applies to any stochastic process defined by a master equation.With a view on the processes that we shall study we call H a quantum Hamiltonian and this formulation of the master equation the quantum Hamiltonian formalism.The reason for this choice of language is the fact that for the processes studied below(and,in fact,manyother processes as well)H is the Hamiltonian of some quantum system such as the Heisenberg XXZ Hamiltonian.The steady state of a stochastic system corresponds in this mapping to the ground state of the quantum system.Now,it is straightforward to translate the well-known theorems[44]about the solution of the master equation(2.1)to the Hamiltonian formulation at hand.In particular,the real parts of the eigenvalues E i of H are non-negative,ℜE i≥E0=0,and there are no purely imaginary eigenvalues,which excludes thepossibility of undamped oscillations.Furthermore,if the initial distribution P0({σ})=P(σ;0)= σ|P0 satisfies0≤P0({σ})≤1and s|P0 =1,it follows that since|P =exp(−Ht)|P0 (2.6) the relations0≤ σ|P ≤1and s|P =1hold for all times t.This guarantees the probabilistic interpretation.Then time-dependent averages of an observable F are given by the matrix element<F>(t)= σF(σ)P(σ;t)= s|F|P = s|F exp(−Ht)|P0 (2.7) Conversely,if a matrix H satisfies the conditionss| H=0, σ| H|τ ≤0for allσ=τ(2.8) it follows that H is the generator of a stochastic process[44].These conditions will play a major role later on.We shall refer to thefirst as probability conservation condition and to the second as positivity conditions.In what follows,we shall be mainly interested in averages of particle numbers n j at site j and their correlators.These can be expressed in the quantum spin formulation in terms of the projector1˜n j=4We stress that the structure of these matrix elements is quite distinct from expectation values in ordinary quantum mechanics where one always considers matrix elements between right and left states that are hermitean conjugates.hand,if there is in the L→∞limit a continuous spectrum down to E0=0,one expects an algebraic approach of the correlators to the steady state.The recent interest in this setup comes from the integrability of quantum Hamiltonians in one dimension[19,21,23,24,25,26,27]5.As the paradigmatic example,consider the asymmetric simple exclusion process where particles are diffusing to the right,A+∅→∅+A with rate1/q and diffusing to the left∅+A→A+∅with rate q.The Hamiltonian generating the time evolution of the system can,for free boundary conditions,be written in the form[24]H=−12 q+q−1 σz jσz j+1−1 −12and2depending on theparticle density[21,47,27].The basic mechanism behind this is explained in appendix F.In fact,integrable quantum Hamiltonians can be found for much more general systems.We restrict our attention here to models with nearest-neighbor interactions and only consider a single species of particles.Unfortunately,there is no standard notation for the various rates.In table1we give the possible reaction-diffusion processes together with their rates,providing at the same time a dictionary between the notations used by different authors.In this paper,we shall use the notation employed in [10].For the time being and for purposes of illustration let us consider besides diffusion only those reactions which irreversibly reduce the number of particles(that is,βL,R=σL,R=ν=0).For temporary convenience we rescaleα→Dαand define alsoD= γLγRδLδR D LγLδL 5Or equally,from the integrability of transfer matrices for discrete time dynamics[20,22]diffusion to the left D L w1,1(1,0)A+∅→∅+A a23Γ1001 pair annihilation2αw1,1(0,0)A+A→∅+A a24Γ1101 coagulation to the leftγL w0,1(1,0)A+∅→∅+∅a13Γ1000 death at the rightδR w0,1(0,0)∅+A→A+A a42Γ0111 decoagulation to the rightβR w0,1(1,1)∅+∅→A+A a41Γ0011 creation at the rightσR w0,1(0,1)∅+∅→A+∅a31Γ0010[10][24]2 q+q−1 (1+δ−γ)−α,h=12L−1j=1 σx jσx j+1+σy jσy j+1+∆ σz jσz j+1−1+h σz j+σz j+1−2 −12(σx±iσy)are the one-particle annihilation/creation operators.Remarkably,the spectrum of H is independent of the terms contained in (2.16),that is spec(H )=spec(DH XXZ (h,∆,δ))[24].To see this,recall that the XXZ Hamiltonian conserves the number of particles while the reaction terms irreversibly decrease the total particle number.Thus,H can be written in a block diagonal formH = N 0X δX αN 1X γ,δX αN 2X γ,δ......... (2.17)where N n refers to the n -particle states and X are the reaction matrix elements.Because of the identitydet A X 0B =det A det B (2.18)it is clear that the elements of (2.16)do not enter into the characteristic polynomial 6of H .The phase diagram for H XXZ (h,∆,δ)is known [49,50].For our purposes,we need the following.From (2.13),only the portion of the phase diagram where h +∆≥1is important for us.The spectrum always has a finite gap when h +∆>1,which is realized whenever δ=0or q =1.Then the ground state is a trivial ferromagnetic frozen state.The spectrum is gapless for ∆+h =1,where the system undergoes a Pokrovsky-Talapov transition.This situation occurs for δ=0and q =1.We have thus identified the cases where the model approaches the steady state exponentially (non-vanishing gap)or algebraically (gapless).A special point is ∆=0where H XXZ becomes a free fermion system and thus in certain cases not only the spectrum may be obtained,but also correlation functions can be calculated explicitly (see below).While large classes of reaction-diffusion problems are now recognised as being integrable,see [23,25,26]for lists including systems with more than one kind of particles 7,it is still far from obvious how to exploit the algebraic structure hidden beneath it in order to get explicit expressions for the desired particle number correlators for ∆=0.A very interesting alternative was proposed in [48],where subsets of observables were identified for which closed equation of motion can be obtained,thus leading to partially integrable systems.In any case,it is important to realize that the knowledge about the spectrum (and,in certain cases such as the free fermion case ∆=0,about correlators)does nott .come from the assumption that the Hamiltonian is stochastic,but from its integrability.It is therefore natural to ask whether one canfind new integrable non-equilibrium systems from transformations of known integrable quantum chains.Specifically,we shall investigate the transformation[38,39,10]H=B H B−1,B=L j=1B j(2.19) where H is a quantum Hamiltonian with known properties, H a stochastic Hamiltonian and B j is the transformation matrix B acting on the site j.From now on,we shall focus on translationally invariant systems,i.e.we shall consider periodic boundary conditions.To study the effect of the transformation B,it is sufficient to consider the effect on a two-particle Hamiltonian H j,j+1,that is we writeH=Lj=111⊗···⊗1j−1⊗H j,j+1⊗1j+2···⊗1L(2.20)where1ℓis the unit matrix acting on the siteℓ.For the model(2.14)with left-right symmetry,that is q=1,we have for exampleH j,j+1=D0−δ−δ−2α01+δ−1−γ0−11+δ−γ0002(α+γ)(2.21)Transformations of the type(2.19)have been mainly studied when both H and H represent stochastic systems.Besides,an equivalent way of relating stochastic systems was developed[52]in the context of the Lagrangian formulation of the model(see below),which is more suitable forfield theory techniques. In particular,these transformations allow to treat the general model(2.21),since the observables in the two systems are simply related[10,38,39,40,52].The results for the long-time behaviour of the one-and two-point functions for translationally invariant initial conditions are collected in table2.For the derivation,see appendix E.From the spectrum of H,we would naively expect exponential factors e−2kδt to be present in the k-point correlator C k,but we also see that for example algebraic prefactors are not readily predicted from the spectrum alone.This expectation,however,is only valid provided there are no bound states in the system.This is so as long the model stays sufficiently close to the caseδ=α+γ−1,where the exact spectrum of H can be found from free fermion techniques.In general,however,one can show from the Bethe ansatz[53,35,36,37]that there does exist a bound state in the two-particle sector,which has the energy4δ+4−2∆−2/∆.8While the results given in table2are valid for homogeneous initialδexp(−2δt)t−1/2exp(−4δt)>α+γ9The above analysis assumes that the associated amplitudes are non-vanishing.This is not always so,as can be seen in the calculation of the correlator<n j(t)nℓ(0)>for a model in which the only non-vanishing rates areαandν.Although a bound state is known to be present,the associated amplitude can be shown to vanish.We thank R.B.Stinchcombe for pointing this out to us.10The radioactive decay of particles is described in this setting by the conditionsα=0andγ=δ.11We limit ourselves to these two types of integrable systems for pragmatic reasons.In fact,for the second type of integrable system we consider here we merely use the integrability of the spectrum and do not even ask whether or not the entire system might be integrable.A sufficient criterion to establish integrability of the full Hamiltonian H is provided by showing that the H j,j+1satisfy a Hecke algebra.It can be shown that forδ=0in the model(2.14)the entire non-symmetric Hamiltonian matrix and not just the spectrum-determining part is integrable[24].See[23]for a list of integrable stochastic Hamiltonians through the Hecke algebra technique.fermions.We shall give in the next section the complete list of stochastic systems with spatially constant reaction rates which can be transformed into this form.2.The most general Hamiltonian with the spectrum of the XXZ chain and with real matrix elements.Here we shall obtain a new3-parameter manifold(after normalization)of integrable stochastic processes.Before starting this,however,it might be useful to recall briefly how results obtained from the quan-tum Hamiltonian formulation of reaction-diffusion systems presented here compare with the Lagrangian techniques,as developed in[15,17,56].See[13]for a recent review.As for the quantum Hamiltonian formulation,the starting point is the master equation.The creation and destruction of particles is conveniently described in a Fock space formalism,where the state vector becomes|P(t) = σp(n1,n2,...;t) a†1 n1 a†2 n2···|0 (2.22) where a†i creates a particle at site i and p(n1,n2,...;t)is the probability of having n1particles at site 1,n2particles at site2and so on at time t.Consider for example the case when only diffusion and annihilation occur.Then the Hamiltonian isH=D (i,j)(a†i−a†j)(a i−a j)−2α i a2i−a†2i a2i → D(∇a†)(∇a)−2α a2−a†2a2 d d x(2.23) where a formal continuum limit is taken12.One then goes over to a path integral representation involving fields a(x,t)and a∗(x,t)and an action S[a,a∗].In order to reduce the calculation of avarages to the usual QFT expectation values,it is customary to perform a shift a∗=1+¯a.Then the action becomes [15,17,56]S[a,¯a]= ¯a∂t a+D∇¯a∇a+4α¯a a2+2α¯a2a2 dtd d x(2.24) Remarkably,since the particle number can only decrease,the diagrammatics of the associatedfield theory is greatly simplified.In particular,there are no loop corrections to the propagator and thus no wave function renormalization[15,17,56]and only the reaction rateαneeds to be renormalized.This can be done by summing up the corresponding diagrams to all orders,with the result that the one-loop beta function is exact.From the renormalization group equations it then follows that the upper critical dimension is at d∗=2and that the exponent y describing the decay of the mean particle number(1.1)is given by y=min(1,d/2),in agreement with previous heuristic arguments[6,59].In particular,it transpires that the whole probability distribution forfluctuations becomes universal in the late time regime[13].What is the analogue of the similarity transformation(2.19)in the Lagrangian formulation?To see this,consider the process with only diffusion,annihilation and coagulation present[52].The action takes the form,where V describes the interactions of the particles undergoing a reactionSλ= dtdx¯a ˙a−D∇2a + dtdxdx′V(|x−x′|)[¯a(x)¯a(x′)+λ¯a(x)]a(x)a(x′)(2.25) such that forλ=1only coagulation and forλ=2only annihilation reactions occur.Following [52],consider the potentials Vα,γfor pure annihilation and coagulation,respectively,to be of the form Vα(x)=αV(x)and Vγ(x)=γV(x).Then2α+γλ=which is diagonalizable through a Jordan-Wigner transformation followed by a Bogoliubov transfor-mation or by a canonical transformation as described in appendix A.Here,D 1,2,η1,2,h 1,2are free parameters.In the following,we write h =h 1+h 2,g =h 1−h 2and η2=η1η2.We shall consider in this section η=0.The case η=0is a special case of a Hamiltonian with XXZ spectrum and will be con-sidered in the next ing (2.20),we can write down the matrix describing the nearest-neighbor interactionsH j,j +1=− h −C 00η10g −C D 100D 2−g −C 0η200−h −C (3.2)and we look for a matrix Hthrough the transformation H =B H B −1,B =L j =1B j (3.3)and describing a stochastic system.Following the logic described in the preceding section we want to calculate correlation functions of the stochastic system in terms of correlators of the non-stochastic model which we can solve.We therefore rewrite a correlators |˜n x 1(t 1)...˜n x k (t k )|P 0 = s |˜n x 1exp − H (t 1−t 2) ˜n x 2...˜n x k exp− Ht k |P 0 (3.4)in terms of operators transformed using B ,thus reducing this correlator to a matrix element computable through free fermion techniques.Inverting this strategy,one may first calculate matrix elements in the free fermion system,and then obtain the corresponding quantity for all stochastic processes related to this system by choosing an appropriate B .This is the strength of this approach,illustrated in section 5for the density ˜ρ(t )as a function of time for an uncorrelated initial state with initial density ˜ρ0.A single calculation gives ˜ρ(t )for all stochastic processes related to the free fermion system (3.1).In order to find a convenient parametrization for B we first fix the determinant of B to be 1whichis no loss of generality since B must be non-singular and H is independent of det B .We can then write B in a parametrization analogous to the Euler angles (alternatives are discussed in appendix B)B = √a −1cosh φsinh φsinh φcosh φ b 00b −1 (3.5)with transformation parameters a,b,φ.Of these,we can always arrange for b =1,since otherwise,its effect could be absorbed by redefining η1→b 4η1and η2→b −4η2.So we are left with just two transformation parameters a and φ.Below,we shall work with Y defined byY =e 2φ(3.6)In order to ensure that H is stochastic we shall have to satisfy the conditions(2.8).Let C m= 4k=1( H j,j+1)k,m denote the sum of the elements of the m-th column of H.Then,up to boundary terms inσz1,L(which are absent for periodic boundary conditions)and up to an additive constant in H (which will befixed later by specifying the constant C),probability conservation(2.8)is implemented by demanding thatC1= C4=12(−1+a+Y+aY)2,η2=(D1+D2−2h)(−1+a+Y+aY)22(ϕL+ϕR),ϕ′=1In this paper,we study exclusively periodic boundary conditions.Thus it is sufficient to impose the positivity conditons(2.8)on the parity symmetric combinations of the matrix elements of H and on two other combinations of transformed matrix elements in which the terms containing x,y cancel.This reduces the number of inequalities one has to satisfy by two.It is important to keep this distinction between the transformed matrix elements(which occur in H j,j+1)and the actual rates of the stochastic system(which occur in H phys j,j+1)which have all to be positive.Next,we have to write down the elements of the transformed matrix H j,j+1in terms of the matrix elements of H j,j+1and the transformation parameters.To simplify expressions,we make use of the freedom to take the normalization of time scaleD1+D2=2(3.12) and we shall consider the other possible case,when D1+D2=0,in appendix ing the convention of(3.9),we get for the parity symmetric matrix elements−2 α=a2(−1+a−Y2−aY2)·F1·N− γ=1(a2−1)(Y2−1)·F2·N2a− δ=a(Y2−1)(1−a+Y2+aY2)·F3·N− β=−(Y2−1)(−1+a+Y2+aY2)·F3·N− D=1It is remarkable that the matrix elements can be factorised in terms of only very few building blocks. This observation is going to be essential in the classification of the possible stochastic systems.Whether this factorization property has a deeper algebraic meaning is still open.Note that if we use the scaling 1a(Y2−1)8Yσ′+x=(D1−D2+2g)1a(Y2−1)8Y− β′−x=(D1−D2−2g)1(Y2+1)(3.15)4YIn order to get a stochastic system from the matrix elements(3.13,3.15),we must implement the positivity conditions(2.8)on the parity symmetric rates α, γ, ν, σ, δ, β, D.These conditions completely determine the transformation matrix B.The physical systems thus found will have left-right symmetric reaction-diffusion rates.Then,in a second step and using the extra freedom coming from adding the divergence terms to H phys j,j+1as done in(3.11),we shall identify free fermion systems with left-right biased diffusion and reaction rates.We now turn to the analysis of the positivity conditions(2.8).3.2Reality of the transformation parameters a,YBefore embarking on checking the positivity of the symmetric rates(3.13),it is useful to break the problem into smaller pieces.It is a necessary condition to positivity that all matrix elements of H are real.This reality condition allows us to distinguish a few subcases.First,for Y2=1,the transformation from H to H merely amounts to the diagonal transformation encountered before[61].So from now on we always assume Y=1,−1.Second,since the ratios γ′/ σ′and δ′/ β′must be real,it follows from (3.15)thata2real(3.16) and we distinguish the following.1.a real.Then,since2 α/ γis real,it follows thata(−1+a−Y2−aY2)。