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2017航海英语复习九Key word 34: Fire fighting （95）B1617. All of the following are part of the fire triangle EXCEPT ______.A. fuelB. electricityC. oxygenD. heat【知识点】燃烧三要素【解析】不是燃烧三角形一部分的是：电气。
相关题目B1727. It is used for extinguishing fires because it reduces __in the air to the point where combustion stops.A. the concentration of oxygenB. the temperatureC. the fuelD. the heatD1731. Carbon dioxide flooding system is used for extinguishing fires because it reduces the concentration of oxygen in the air to______A .flashing pointB .combustion point C. auto-ignition point D. lower explosive limitC2092. Except in rare cases, it is impossible to extinguish a shipboard fire by ______.A. removing the heatB. removing the oxygenC. removing the fuelD. interrupting the chain reactionA2133. Oil fires are best extinguished by ______.A. cutting off the supply of oxygenB. removing the fuelC. cooling below the ignition temperatureD. spraying with waterB2189. For most products, the fire will die out when the oxygen content is reduced to ________.A.10%B.12%C.15%D.21%【解析】对多数物质而言，氧气含量降至12%，火将熄灭。
acetate 醋酸盐acid 酸Actinium(Ac) 锕aldehyde 醛alkali 碱,强碱alkalinity 碱性alkalinization 碱化alkaloid 生物碱alloy 合金Aluminium(Al) 铝Americium(Am) 镅ammonia 氨analysis 分解anhydride 酐anion 阴离子anode 阳极,正极Antimony(Sb) 锑apparatus 设备aqua fortis 王水Argon(Ar) 氩Arsenic(As) 砷asphalt 沥青Astatine(At) 砹atom 原子atomic mass 原子质量atomic number 原子数atomic weight 原子量Barium(Ba) 钡base 碱benzene 苯Berkelium(Bk) 锫Beryllium(Be) 铍Bismuth(Bi) 铋bivalent 二价body 物体bond 原子的聚合Boron(B) 硼Bromine(Br) 溴Bunsen burner 本生灯burette 滴定管butane 丁烷Cadmium(Cd) 镉Caesium(Cs) 铯Calcium(Ca) 钙Californium(Cf) 锎Carbon(C) 碳catalysis 催化作用catalyst 催化剂cathode 阴极,负极cation 阳离子caustic potash 苛性钾caustic soda 苛性钠Cerium(Ce) 铈chemical fiber 化学纤维Chlorine(Cl) 氯Chromium(Cr) 铬Cobalt(Co) 钴combination 合成作用combustion 燃烧compound 合成物compound 化合物Copper(Cu) 铜cracking 裂化crucible pot, melting pot 坩埚crude oil, crude 原油cupel 烤钵Curium(Cm) 锔derivative 衍生物dissolution 分解distillation column 分裂蒸馏塔distillation 蒸馏Dysprosium(Dy) 镝Einsteinium(Es) 锿electrode 电极electrolysis 电解electrolyte 电解质electron 电子element 元素endothermic reaction 吸热反应Erbium(Er) 铒ester 酯Europium(Eu) 铕exothermic reaction 放热反应fatty acid 脂肪酸fermentation 发酵Fermium(Fm) 镄filter 滤管flask 烧瓶Fluorine(F) 氟fractional distillation 分馏fractionating tower 分馏塔fractionation 分馏Francium(Fr) 钫fuel 燃料fusion, melting 熔解Gadolinium(Gd) 钆Gallium(Ga) 镓gas oil 柴油gel 凝胶体Germanium(Ge) 锗Gold(Au) 金graduate, graduated flask 量筒,量杯gram atom 克原子Hafnium(Hf) 铪halogen 成盐元素Helium(He) 氦high-grade petrol, high-octane petrol 高级汽油,高辛烷值汽油Holmium(Ho) 钬hydracid 氢酸hydrate 水合物hydrocarbon 碳氢化合物,羟hydrocarbon 烃,碳氢化合物hydrochloric acid 盐酸hydrogen sulfide 氢化硫Hydrogen(H) 氢hydrolysis 水解hydrosulphuric acid 氢硫酸hydroxide 氢氧化物,羟化物Indium(In) 铟inorganic chemistry 无机化学Iodine(I) 碘ion 离子Iridium(Ir) 铱Iron(Fe) 铁isomer 同分异物现象isomerism, isomery 同分异物现象isotope 同位素kerosene, karaffin oil 煤油Krypton(Kr) 氪Lanthanum(La) 镧Lawrencium(Lr) 铹Lead(Pb) 铅Lithium(Li) 锂litmus paper 石蕊试纸litmus 石蕊LNG, liquefied natural gas 液化天然气LPG, liquefied petroleum gas 液化石油气lubricating oil 润滑油Lutetium(Lu) 镥Magnesium(Mg) 镁Manganese(Mn) 锰matrass 卵形瓶Mendelevium(Md) 钔Mercury(Hg) 汞metal 金属metalloid 非金属methane 甲烷,沼气mixture 混合molecule 分子Molybdenum(Mo) 钼monovalent 单价natural gas 天然气Neodymium(Nd) 钕Neon(Ne) 氖Neptunium(Np) 镎Nickel(Ni) 镍Niobium(Nb) 铌nitric acid 硝酸Nitrogen(N) 氮Nobelium(No) 锘Nuclear Fusion 核聚变octane number 辛烷数,辛烷值olefin 烯烃organic acid 有机酸organic chemistry 有机化学Osmium(Os) 锇oxide 氧化物oxidization, oxidation 氧化Oxygen(O) 氧Palladium(Pd) 钯paraffin 石蜡petrol 汽油(美作:gasoline)PH indicator PH值指示剂,氢离子(浓度的)负指数指示剂phosphate 磷酸盐Phosphorus(P) 磷pipette 吸液管plastic 塑料Platinum(Pt) 铂Plutonium(Pu) 钚Polonium(Po) 钋polymer 聚合物polymerizing, polymerization 聚合potassium carbonate 碳酸钾Potassium(K) 钾Praseodymium(Pr) 镨precipitation 沉淀product 产物electrochemical analysis 电化学分析on-line analysis 在线分析macro analysis 常量分析characteristic 表征micro analysis 微量分析deformation analysis 形态分析semimicro analysis 半微量分析systematical error 系统误差routine analysis 常规分析random error 偶然误差arbitration analysis 仲裁分析gross error 过失误差normal distribution 正态分布accuracy 准确度deviation偏差precision 精密度relative standard deviation 相对标准偏差（RSD）coefficient variation 变异系数（CV）confidence level 置信水平confidence interval 置信区间significant test 显著性检验significant figure 有效数字standard solution 标准溶液titration 滴定stoichiometric point 化学计量点end point滴定终点titration error 滴定误差primary standard 基准物质amount of substance 物质的量standardization 标定chemical reaction 化学反应concentration浓度chemical equilibrium 化学平衡titer 滴定度general equation for a chemical reaction化学反应的通式proton theory of acid-base 酸碱质子理论acid-base titration 酸碱滴定法dissociation constant 解离常数conjugate acid-base pair 共轭酸碱对acetic acid 乙酸hydronium ion水合氢离子electrolyte 电解质ion-product constant of water 水的离子积ionization 电离proton condition 质子平衡zero level零水准buffer solution缓冲溶液methyl orange 甲基橙acid-base indicator 酸碱指示剂phenolphthalein 酚酞coordination compound 配位化合物center ion 中心离子cumulative stability constant 累积稳定常数alpha coefficient 酸效应系数overall stability constant 总稳定常数ligand 配位体ethylenediamine tetraacetic acid 乙二胺四乙酸side reaction coefficient 副反应系数coordination atom 配位原子coordination number 配位数lone pair electron 孤对电子chelate compound 螯合物metal indicator 金属指示剂chelating agent 螯合剂masking 掩蔽demasking 解蔽electron 电子catalysis 催化oxidation氧化catalyst 催化剂reduction 还原catalytic reaction 催化反应reaction rate 反应速率electrode potential 电极电势activation energy 反应的活化能redox couple 氧化还原电对potassium permanganate 高锰酸钾iodimetry碘量法potassium dichromate 重铬酸钾cerimetry 铈量法redox indicator 氧化还原指示oxygen consuming 耗氧量（OC）chemical oxygen demanded 化学需氧量(COD) dissolved oxygen 溶解氧(DO)precipitation 沉淀反应argentimetry 银量法heterogeneous equilibrium of ions 多相离子平衡aging 陈化postprecipitation 继沉淀coprecipitation 共沉淀ignition 灼烧fitration 过滤decantation 倾泻法chemical factor 化学因数spectrophotometry 分光光度法colorimetry 比色分析transmittance 透光率absorptivity 吸光率calibration curve 校正曲线standard curve 标准曲线monochromator 单色器source 光源wavelength dispersion 色散absorption cell吸收池detector 检测系统bathochromic shift 红移Molar absorptivity 摩尔吸光系数hypochromic shift 紫移acetylene 乙炔ethylene 乙烯acetylating agent 乙酰化剂acetic acid 乙酸adiethyl ether 乙醚ethyl alcohol 乙醇acetaldehtde 乙醛β-dicarbontl compound β–二羰基化合物bimolecular elimination 双分子消除反应bimolecular nucleophilic substitution 双分子亲核取代反应open chain compound 开链族化合物molecular orbital theory 分子轨道理论chiral molecule 手性分子tautomerism 互变异构现象reaction mechanism 反应历程chemical shift 化学位移Walden inversio 瓦尔登反转nEnantiomorph 对映体addition rea ction 加成反应dextro- 右旋levo- 左旋stereochemistry 立体化学stereo isomer 立体异构体Lucas reagent 卢卡斯试剂covalent bond 共价键conjugated diene 共轭二烯烃conjugated double bond 共轭双键conjugated system 共轭体系conjugated effect 共轭效应isomer 同分异构体isomerism 同分异构现象organic chemistry 有机化学hybridization 杂化hybrid orbital 杂化轨道heterocyclic compound 杂环化合物peroxide effect 过氧化物效应tvalence bond theory 价键理论sequence rule 次序规则electron-attracting grou p 吸电子基Huckel rule 休克尔规则Hinsberg test 兴斯堡试验infrared spectrum 红外光谱Michael reacton 麦克尔反应halogenated hydrocarbon 卤代烃haloform reaction 卤仿反应systematic nomenclatur 系统命名法eNewman projection 纽曼投影式aromatic compound 芳香族化合物aromatic character 芳香性rClaisen condensation reaction克莱森酯缩合反应Claisen rearrangement 克莱森重排Diels-Alder reation 狄尔斯-阿尔得反应Clemmensen reduction 克莱门森还原Cannizzaro reaction 坎尼扎罗反应positional isomers 位置异构体unimolecular elimination reaction 单分子消除反应unimolecular nucleophilic substitution 单分子亲核取代反应benzene 苯functional grou 官能团pconfiguration 构型conformation 构象confomational isome 构象异构体electrophilic addition 亲电加成electrophilic reagent 亲电试剂nucleophilic addition 亲核加成nucleophilic reagent 亲核试剂nucleophilic substitution reaction亲核取代反应active intermediate 活性中间体Saytzeff rule 查依采夫规则cis-trans isomerism 顺反异构inductive effect 诱导效应tFehling’s reagent 费林试剂phase transfer catalysis 相转移催化作用aliphatic compound 脂肪族化合物elimination reaction 消除反应Grignard reagent 格利雅试剂nuclear magnetic resonance 核磁共振alkene 烯烃allyl cation 烯丙基正离子leaving group 离去基团optical activity 旋光性boat confomation 船型构象silver mirror reaction 银镜反应Fischer projection 菲舍尔投影式Kekule structure 凯库勒结构式Friedel-Crafts reaction 傅列德尔-克拉夫茨反应Ketone 酮carboxylic acid 羧酸carboxylic acid derivative 羧酸衍生物hydroboration 硼氢化反应bond oength 键长bond energy 键能bond angle 键角carbohydrate 碳水化合物carbocation 碳正离子carbanion 碳负离子alcohol 醇Gofmann rule 霍夫曼规则Aldehyde 醛Ether 醚Polymer 聚合物product 化学反应产物Promethium(Pm) 钷Protactinium(Pa) 镤purification 净化qualitative analysis 定性分析quantitative analysis 定量分析chemical analysis 化学分析instrumental analysis 仪器分析titrimetry 滴定分析gravimetric analysis 重量分析法regent 试剂chromatographic analysis 色谱分析radical 基Radium(Ra) 镭Radon(Rn) 氡reagent 试剂reducer 还原剂refinery 炼油厂refining 炼油reforming 重整retort 曲颈甑reversible 可逆的Rhenium(Re) 铼Rhodium(Rh) 铑Rubidium(Rb) 铷Ruthenium(Ru) 钌salt 盐Samarium(Sm) 钐Scandium(Sc) 钪Selenium(Se) 硒separation 分离series 系列Silicon(Si) 硅Silver(Ag) 银soda 苏打sodium carbonate 碳酸钠Sodium(Na) 钠solution 溶解solvent 溶剂still 蒸馏釜stirring rod 搅拌棒Strontium(Sr) 锶structural formula 分子式Sulphur(S) 锍sulphuric acid 硫酸symbol 复合synthesis 合成synthetic rubber 合成橡胶Tantalum(Ta) 钽Technetium(Tc) 锝Tellurium(Te) 碲Terbium(Tb) 铽test tube 试管Thallium(Tl) 铊Thorium(Th) 钍Thulium(Tm) 铥Tin(Sn) 锡Titanium(Ti) 钛to calcine 煅烧to dehydrate 脱水to distil, to distill 蒸馏to hydrate 水合,水化to hydrogenate 氢化to neutralize 中和to oxidize 氧化to oxygenate, to oxidize 脱氧,氧化to precipitate 沉淀Tungsten(W) 钨Uranium(U) 铀valence, valency 价Vanadium(V) 钒vaseline 凡士林Xenon(Xe) 氙Ytterbium(Yb) 镱Yttrium(Y) 钇Zinc(Zn) 锌Zirconium(Zr) 锆理想气体状态方程Partial Pressures 分压Real Gases: Deviation from Ideal Behavior 真实气体：对理想气体行为的偏离The van der Waals Equation 范德华方程System and Surroundings 系统与环境State and State Functions 状态与状态函数Process 过程Phase 相The First Law of Thermodynamics 热力学第一定律Heat and Work 热与功Endothermic and Exothermic Processes 吸热与发热过程Enthalpies of Reactions 反应热Hess’s Law 盖斯定律Enthalpies of Formation 生成焓Reaction Rates 反应速率Reaction Order 反应级数Rate Constants 速率常数Activation Energy 活化能The Arrhenius Equation 阿累尼乌斯方程Reaction Mechanisms 反应机理Homogeneous Catalysis 均相催化剂Heterogeneous Catalysis 非均相催化剂Enzymes 酶The Equilibrium Constant 平衡常数the Direction of Reaction 反应方向Le Chatelier’s Principle 列·沙特列原理Effects of V olume, Pressure, Temperature Changes and Catalysts 体积，压力，温度变化以及催化剂的影响Spontaneous Processes 自发过程Entropy (Standard Entropy) 熵（标准熵）The Second Law of Thermodynamics 热力学第二定律Entropy Changes 熵变Standard Free-Energy Changes 标准自由能变Acid-Bases 酸碱The Dissociation of Water 水离解The Proton in Water 水合质子The pH Scales pH值Bronsted-Lowry Acids and Bases Bronsted-Lowry 酸和碱Proton-Transfer Reactions 质子转移反应Conjugate Acid-Base Pairs 共轭酸碱对Relative Strength of Acids and Bases 酸碱的相对强度Lewis Acids and Bases 路易斯酸碱Hydrolysis of Metal Ions 金属离子的水解Buffer Solutions 缓冲溶液The Common-Ion Effects 同离子效应Buffer Capacity 缓冲容量Formation of Complex Ions 配离子的形成Solubility 溶解度The Solubility-Product Constant Ksp 溶度积常数Precipitation and separation of Ions 离子的沉淀与分离Selective Precipitation of Ions 离子的选择沉淀Oxidation-Reduction Reactions 氧化还原反应Oxidation Number 氧化数Balancing Oxidation-Reduction Equations 氧化还原反应方程的配平Half-Reaction 半反应Galvani Cell 原电池V oltaic Cell 伏特电池Cell EMF 电池电动势Standard Electrode Potentials 标准电极电势Oxidizing and Reducing Agents 氧化剂和还原剂The Nernst Equation 能斯特方程Electrolysis 电解The Wave Behavior of Electrons 电子的波动性Bohr’s Model of The Hydrogen Atom 氢原子的波尔模型Line Spectra 线光谱Quantum Numbers 量子数Electron Spin 电子自旋Atomic Orbital 原子轨道The s (p, d, f) Orbital s（p，d，f）轨道Many-Electron Atoms 多电子原子Energies of Orbital 轨道能量The Pauli Exclusion Principle 泡林不相容原理Electron Configurations 电子构型The Periodic Table 周期表Row 行Group 族Isotopes, Atomic Numbers, and Mass Numbers 同位素，原子数，质量数Periodic Properties of the Elements 元素的周期律Radius of Atoms 原子半径Ionization Energy 电离能Electronegativity 电负性Effective Nuclear Charge 有效核电荷Electron Affinities 亲电性Metals 金属Nonmetals 非金属Valence Bond Theory 价键理论Covalence Bond 共价键Orbital Overlap 轨道重叠Multiple Bonds 重键Hybrid Orbital 杂化轨道The VSEPR Model 价层电子对互斥理论Molecular Geometries 分子空间构型Molecular Orbital 分子轨道Diatomic Molecules 双原子分子Bond Length 键长Bond Order 键级Bond Angles 键角Bond Enthalpies 键能Bond Polarity 键矩Dipole Moments 偶极矩Polarity Molecules 极性分子Polyatomic Molecules 多原子分子Crystal Structure 晶体结构Non-Crystal 非晶体Close Packing of Spheres 球密堆积Metallic Solids 金属晶体Metallic Bond 金属键Alloys 合金Ionic Solids 离子晶体Ion-Dipole Forces 离子偶极力Molecular Forces 分子间力Intermolecular Forces 分子间作用力Hydrogen Bonding 氢键Covalent-Network Solids 原子晶体Compounds 化合物The Nomenclature, Composition and Structure of Complexes 配合物的命名，组成和结构Charges, Coordination Numbers, and Geometries 电荷数、配位数、及几何构型Chelates 螯合物Isomerism 异构现象Structural Isomerism 结构异构Stereoisomerism 立体异构Magnetism 磁性Electron Configurations in Octahedral Complexes 八面体构型配合物的电子分布Tetrahedral and Square-planar Complexes 四面体和平面四边形配合物General Characteristics 共性s-Block Elements s区元素Alkali Metals 碱金属Alkaline Earth Metals 碱土金属Hydrides 氢化物Oxides 氧化物Peroxides and Superoxides 过氧化物和超氧化物Hydroxides 氢氧化物Salts 盐p-Block Elements p区元素Boron Group (Boron, Aluminium, Gallium, Indium, Thallium) 硼族（硼，铝，镓，铟，铊）Borane 硼烷Carbon Group (Carbon, Silicon, Germanium, Tin, Lead) 碳族（碳，硅，锗，锡，铅）Graphite, Carbon Monoxide, Carbon Dioxide 石墨，一氧化碳，二氧化碳Carbonic Acid, Carbonates and Carbides 碳酸，碳酸盐，碳化物Occurrence and Preparation of Silicon 硅的存在和制备Silicic Acid，Silicates 硅酸，硅酸盐Nitrogen Group (Phosphorus, Arsenic, Antimony, and Bismuth) 氮族（磷，砷，锑，铋）Ammonia, Nitric Acid, Phosphoric Acid 氨，硝酸，磷酸Phosphorates, phosphorus Halides 磷酸盐，卤化磷Oxygen Group (Oxygen, Sulfur, Selenium, and Tellurium) 氧族元素（氧，硫，硒，碲）Ozone, Hydrogen Peroxide 臭氧，过氧化氢Sulfides 硫化物Halogens (Fluorine, Chlorine, Bromine, Iodine) 卤素（氟，氯，溴，碘）Halides, Chloride 卤化物，氯化物The Noble Gases 稀有气体Noble-Gas Compounds 稀有气体化合物d-Block elements d区元素Transition Metals 过渡金属Potassium Dichromate 重铬酸钾Potassium Permanganate 高锰酸钾Iron Copper Zinc Mercury 铁，铜，锌，汞f-Block Elements f区元素Lanthanides 镧系元素Radioactivity 放射性Nuclear Chemistry 核化学Nuclear Fission 核裂变analytical chemistry 分析化学。
Biologists and chemists divide compounds into two principal classes, inorganic and organic. Inorg anic compounds are defined as molecules, usually small, that typically lack carbon and in which io nic bonds may play an important role. Inorganic compounds include water, oxygen, carbon dioxid e, and many salts, acids, and bases.生物学家和化学家分裂成两个主要种类化合物、无机和有机。
无机化合物被定义为分子,通常小,通常缺乏的碳离子束缚,那么它就能起到重要的作用。
无机化合物包括水、氧气、二氧化碳和许多盐、酸、和根据地。
All living organisms require a wide variety of inorganic compounds for growth, repair, maintenan ce, and reproduction. Water is one of the most important, as well as one of the rmost abundant, of t hese compounds, and it is particularly vital to microorganisms. Outside the cell, nutrients are disso lved in water, which facilitates their passage through cell membranes. And inside the cell , water is the medium for most chemical reactions. In fact, water is by far the most abundant component of almost all living cells. Water makes up 5% to 95% or more of each cell, the average being betwee n 65% and 75%. Simply stated, no organism can survive without water 所有生物体需要多种无机化合物的增长、维修、维护、和繁衍。
七年级全球挑战与社会责任英语阅读理解30题1<背景文章>Global warming is a serious problem that the world is facing. It refers to the long-term increase in the average temperature of the Earth's climate system. The main cause of global warming is the increase in greenhouse gases, such as carbon dioxide, methane, and nitrous oxide. These gases trap heat in the atmosphere and cause the temperature to rise.One of the most visible effects of global warming is the melting of glaciers and ice caps. This leads to rising sea levels, which can cause flooding in coastal areas. Global warming also causes changes in weather patterns, such as more extreme heat waves, droughts, and storms.We need to take action to reduce global warming. We can do this by reducing our use of fossil fuels, such as coal, oil, and gas. We can also plant more trees, which absorb carbon dioxide from the atmosphere.1. What is global warming?A. A short-term increase in temperature.B. A long-term increase in the average temperature of the Earth's climate system.C. A decrease in temperature.D. No change in temperature.答案：B。
高三化学有机英语阅读理解30题1<背景文章>Methane, also known as natural gas, is one of the simplest and most important organic compounds. It has a tetrahedral molecular structure with four hydrogen atoms bonded to a single carbon atom. The chemical formula for methane is CH₄.Methane is a colorless and odorless gas at room temperature. However, for safety reasons, a small amount of odorant is added to natural gas so that leaks can be easily detected. Methane is highly flammable and burns with a blue flame, producing carbon dioxide and water.In nature, methane is found in several places. It is a major component of natural gas deposits, which are formed from the decomposition of organic matter over millions of years. Methane is also produced by anaerobic bacteria in swamps, marshes, and the digestive tracts of some animals.Methane has many important uses. It is a clean-burning fuel that is used for heating, cooking, and generating electricity. Methane is also used as a raw material in the production of chemicals such as methanol and ammonia.The properties of methane make it an important compound in bothindustry and everyday life. Its low boiling point and high vapor pressure make it easy to store and transport as a gas. Methane is also relatively stable and does not react easily with other compounds under normal conditions.However, methane can also have negative impacts on the environment. When released into the atmosphere, methane is a potent greenhouse gas, with a global warming potential much higher than that of carbon dioxide. Efforts are being made to reduce methane emissions from sources such as natural gas production and livestock farming.In conclusion, methane is a fascinating and important organic compound with a wide range of properties and uses. Understanding its structure, properties, and environmental impacts is essential for students of chemistry and for anyone interested in the environment and energy.1. Methane has a ___ molecular structure.A. triangularB. tetrahedralC. hexagonalD. octagonal答案：B。
2023届广东省揭阳市四校联考高三下学期二模英语试题一、听力选择题1. Why didn’t the man go to the exhibition?A．Getting tickets would take too much time.B．He didn’t care for Da Vinci’s paintings.C．The ticket was too expensive.2. Why did the man leave Asian Industrial?A．He got promoted.B．He liked marketing.C．He enjoyed electronics.3. What does the man mean?A．He thinks the movie is terrible.B．He likes the movie very much.C．He thinks Eva acted well in the movie.4. What is the woman probably?A．A nurse.B．A teacher.C．A surgeon.5. When does the bank close on Sunday?A．At 9:00 p.m.B．At 5:00 p.m.C．At 4:00 p.m.二、听力选择题6. 听下面一段较长对话，回答以下小题。
1. Where did the woman learn about the apartment?A．On TV.B．In the newspaper.C．On the Internet.2. How much is the monthly rent?A．About £600.B．About £300.C．About £150.3. What will bring about an extra fee?A．Heat.B．Electricity.C．Parking.7. 听下面一段较长对话，回答以下小题。
2024年甘肃省英语初一上学期复习试题及解答参考一、听力部分（本大题有20小题，每小题1分，共20分）1、Question: What does the man say about his weekend plans?A) He plans to visit his grandparents.B) He will stay home and do some homework.C) He is going to a sports event.Answer: BExplanation: The man says, “I’m staying home this weekend to catch up on some homework.” Therefore, the correct answer is B.2、Question: How does the woman feel about the weather today?A) She thinks it’s too hot.B) She prefers the sunny weather.C) She s ays it’s quite pleasant.Answer: CExplanation: The woman says, “It’s quite pleasant today, isn’t it?” which indicates she finds the weather to be enjoyable. Thus, the correct answer isC.3、What are the two subjects that the students are talking about?A. Math and ScienceB. English and HistoryC. Music and ArtD. PE and GeographyAnswer: BExplanation: The students mentioned that they are studying English and History in school, so the correct answer is B.4、How does the weather forecast for tomorrow?A. It will be sunny all day.B. There will be a heavy rain.C. The weather will be cloudy with a chance of rain.D. It will be a windy day.Answer: CExplanation: The weather forecast for tomorrow mentioned that it will be cloudy with a chance of rain, so the correct answer is C.5、What are the speakers discussing?A. The weather forecast for the next week.B. The differences between two cities.C. The books they have read recently.Answer: BExplanation: The conversation includes a comparison between the two cities, with the speakers mentioning the differences in climate, culture, and attractions. Therefore, the correct answer is B.6、Why does the woman want to change her major?A. She is interested in a different field of study.B. She is not enjoying her current major.C. She needs more flexibility in her schedule.Answer: CExplanation: The woman mentions that her current major requires a lot of hours, and she wants to change it for something that allows more flexibility in her schedule. Therefore, the correct answer is C.7、You are listening to a conversation between a student and a teacher.Student: “Mr.Smith, I’m confused about the homework you gave us. Could you explain it again?”Teacher: “Of course. The assignment is to write a short essay about your favorite book. Remember to include three main points and provide examples to support your opinions.”Question: What is the main topic of the homework assignment?A) Reading a bookB) Writing an essayC) Discussing favorite subjectsD) Exploring different genresAnswer: B) Writing an essayExplanation: The teacher explains that the assignment is to write a short essay, making option B the correct answer. The other options are not directly related to the main task.8、You are listening to a news report about a local charity event.Reporter: “This weekend, the local community center will be hosting a charity event to raise funds for the children’s hospital. The event will feature a variety of activities, including a bake sale, a silent auction, and a talent show. All proceeds will go towards supporting the hospital’s programs and services.”Question: What is the main purpose of the charity event?A) To raise funds for the community centerB) To suppo rt the children’s hospitalC) To promote local businessesD) To provide entertainment for the communityAnswer: B) To support the children’s hospitalExplanation: The news report clearly states that the event is to raise funds for the children’s hospital, making option B the correct answer. The other options are not mentioned in the report and are not related to the event’s purpose.9.You are listening to a conversation between a student and a teacher.Student: “Mr.Smith, can I ask you a question about the homework?”Teacher: “Certainly, what’s your question?”Student: “Well, I’m not sure about the answer to the last question on the assignment. It says ‘The boy and the girl played together in the park.’ But I’m confused about the verb tense. Should it be pa st simple or pastcontinuous?”Teacher: “That’s a great question. The correct answer is past simple. The past simple tense is used to talk about actions in the past that have already finished. Since the sentence is describing an event that happened in the past and is not ongoing, we use the past simple tense.”Answer: past simpleExplanation: The teacher explains that the correct tense to use in the sentence is the past simple because it describes a completed action in the past.10.Listen to a short dialogue between two friends discussing their weekend plans.Friend A: “Hey, what are you planning to do this weekend?”Friend B: “I’m thinking of going hiking. How about you?”Friend A: “That sounds fun! But I was thinking of staying in and watching some movies. Do you think that’s a good idea?”Friend B: “Sure, that’s fine. I think we should both do something we enjoy. It’s important to relax and have a good time.”Answer: watching moviesExplanation: Friend A mentions that they were planning to stay in and watch some movies. This is the activity that Friend A is considering for their weekend.11.You are listening to a conversation between a student and a teacher.Student: Excuse me, Mr. Smith, I was wondering if you could explain the homework assignment again.Teacher: Sure, the homework assignment is to write a short essay about your favorite book. Remember to include three reasons why you like it.Question: What is the homework assignment for this week?A) Reading a new bookB) Writing a short essay about a favorite bookC) Discussing the plot of a novelD) Drawing a picture of a characterAnswer: BExplanation: The teacher specifically mentioned that the homework assignment is to write a short essay about a favorite book, which corresponds to optionB.12.You are listening to a phone conversation between two friends.Friend A: Hey, how was your science class today?Friend B: It was okay, but the teacher gave us a pop quiz on the periodic table.Question: What did Friend B mention about the science class?A) The teacher explained the periodic table in detailB) There was a pop quiz on the periodic tableC) They watched a video about the solar systemD) They discussed the properties of waterAnswer: BExplanation: Friend B mentioned that there was a pop quiz on the periodic table,which corresponds to option B.13.You hear a conversation between two friends at the library. Listen carefully and choose the correct answer.A. They are discussing a book they both read.B. They are planning to go to the cinema together.C. They are asking for help with their homework.Answer: AExplanation: The conversation focuses on the book they both read, indicating that they are discussing it together.14.Listen to a short dialogue between a teacher and a student about an upcoming school project. Then answer the question.Question: What is the teacher asking the student to do?A. To finish the project before the deadline.B. To choose a topic for the project.C. To bring their research notes to the next class.Answer: BExplanation: The teacher is guiding the student to choose a topic for the project, which is the main focus of the conversation.15.Question: What did the woman do yesterday afternoon?A. She went to the library.B. She visited her friend.C. She watched a movie at home.Answer: BExplanation: The woman mentioned in the conversation that she had visited her friend yesterday afternoon, which is option B.16.Question: How many books did the student borrow from the library last week?A. TwoB. ThreeC. FourAnswer: CExplanation: The student in the conversation said that he borrowed four books from the library last week, which is option C.17.You are listening to a conversation between two students, Alex and Lily, discussing their weekend plans.Question: What are Alex and Lily planning to do this weekend?A) Go shoppingB) Go to a movieC) Go hikingAnswer: C) Go hikingExplanation: The conversation reveals that Alex and Lily are planning to go hiking this weekend. They talk about how they want to go to a nature reserve and enjoy the beautiful scenery.18.You are listening to a phone call between a teacher and a student,discussing the student’s progress.Question: What is the student’s main concern regarding their studies?A) Difficulty in understanding the math lessonsB) Lack of time for homeworkC) Low grades in the science testsAnswer: C) Low grades in the science testsExplanation: In the phone call, the student expresses their worry about their low grades in the science tests. The teacher offers some advice and encourages the student to study harder to improve their scores.19.You hear a conversation between two students, Alice and Bob, discussing their weekend plans. Listen to the conversation and answer the following question:What activity does Alice plan to do this weekend?A)Go to the movies.B)Visit a museum.C)Go hiking.Answer: B) Visit a museum.Explanation: In the conversation, Alice says, “I think I’ll visit the art museum this weekend.” This indicates that her plan is to visit a museum.20.You hear a short dialogue between a teacher and a student, Sarah, abouta school project. Listen to the dialogue and answer the following question:What is Sarah’s concern about the project?A)She doesn’t understand the instructions.B)She doesn’t have all the required materials.C)She’s worried about the deadline.Answer: C) She’s worried about the deadline.Explanation: The teacher asks Sarah, “How are you doing with the project?” and Sarah replies, “I’m a bit worried about the deadline; I haven’t finished everything yet.” This shows that her main concern is the project’s deadline.二、阅读理解（30分）Reading ComprehensionRead the following passage and answer the questions that follow.The Rainforest: A Treasure Trove of BiodiversityThe rainforest is a lush, green area of land that is home to a vast array of plants, anim als, and insects. Covering approximately 6% of the Earth’s surface, rainforests are found mainly in the Amazon, Congo, and Indonesia. Despite their small size, they are incredibly diverse, housing up to 50% of the world’s known species.One of the most fascinating aspects of the rainforest is its biodiversity. This refers to the variety of life found in a particular habitat, including plants, animals, and microorganisms. The dense vegetation provides a habitat for countless species, many of which are not yet discovered by scientists. The rainforest is often referred to as the “lungs of the Earth” because it produces a significant amount of oxygen through photosynthesis.The rainforest also plays a crucial role in climate regulation. It helps to regulate the Earth’s temperature by absorbing carbon dioxide, which is a greenhouse gas. This process is known as carbon sequestration. The trees and plants in the rainforest release moisture into the atmosphere, which contributes to cloud formation and rainfall.However, the rainforest is facing numerous threats. Deforestation, driven by agricultural expansion, logging, and mining, is the most significant threat to rainforest ecosystems. This not only leads to the loss of habitat for countless species but also contributes to global climate change.1.What is the main topic of the passage?A) The causes of global climate changeB) The importance of the rainforest in maintaining biodiversityC) The economic value of rainforestsD) The challenges of preserving rainforest ecosystems2.According to the passage, what is the role of the rainforest in climate regulation?A) It increases the Earth’s temperature.B) It absorbs carbon dioxide and releases oxygen.C) It reduces the amount of rainfall.D) It contributes to the depletion of the ozone layer.3.What is the primary threat mentioned in the passage as causing deforestation?A) OverpopulationB) Agricultural expansionC) Natural disastersD) The construction of new citiesAnswers:1.B) The importance of the rainforest in maintaining biodiversity2.B) It absorbs carbon dioxide and releases oxygen.3.B) Agricultural expansion三、完型填空（15分）In the small town of Willowbrook, there was once a charming old library that stood at the heart of the community. Every afternoon, a young girl named Lily would visit the library to read her favorite books. However, one day, the library was threatened by a ____(1)__ storm that was expected to cause significant damage.1.A) gentleB) fierceC) mildD) heavyThe librarian, Mrs. Green, knew that the library needed to be ____(2)__ before the storm hit.2.A) closedB) securedC) expandedD) decoratedMrs. Green quickly organized a community meeting to discuss the situation. Many townspeople offered to help. They brought in ____(3)__ and blankets to protect the books and furniture.3.A) sandbagsB) umbrellasC) shovelsD) bucketsAs the storm approached, the townspeople worked tirelessly to ____(4)__ the library.4.A) decorateB) protectC) restoreD) reconstructThankfully, the storm passed without causing much damage. The library was still standing, and the townspeople celebrated their success. They realized that the library was more than just a place to read; it was a symbol of community ____(5)__.5.A) unityB) diversityC) wealthD) progress1.B) fierce2.B) secured3.A) sandbags4.B) protect5.A) unity四、语法填空题（本大题有10小题，每小题1分，共10分）1、I am not sure________I will be able to attend the meeting next week. ( )A. whetherB. thatC. ifD. because答案：A解析：此题考查连词的用法。
All Amerex extinguishers are furnished with a detailed “Owners Manual” containing valuable information. The manual contains information on the installation, use and maintenance of the extinguisher. The extinguisher nameplate (label) contains specific information on “HOW TO USE” the particular extinguisher. The label instructions vary slightly according to type and size. All potential operators should be totally familiar with the instructions on any extinguisher they might be required to use.Amerex manufactures an extensive variety of hand portable and wheeled fire extinguishers, both “compliance” (code required) and “specialty” types. “Specialty” type extinguishers are intended for use on particular types of hazards, so careful attention should be made to locating them in close proximity to the specific hazard they are meant to protect. It is natural for a person to use the extinguisher located nearest to a fire. The most current issue of NFPA-10 should be consulted for minimum recommended fire extinguisher types, placement and travel distances. Your local Amerex Fire Equipment Distributor is professionally equipped to help you evaluate and implement these recommendations.All “Picture Symbols” are detailed below and should be reviewed with all who might be expected to use a fire extinguisher. Everyone should be familiar with these picture symbols which identify the types of fires on which they may be used. The International sign system diagonal red slash indicates a potential danger if the extinguisher is used on that particular type of fire.TYPES OF FIRESCLASS A ORDINARY COMBUSTIBLES:wood, paper, rubber, fabrics and many plastics CLASS B FLAMMABLE LIQUIDS & GASES: gasoline, oils, paint, lacquer and tar CLASS C FIRES INVOLVING LIVE ELECTRICAL EQUIPMENT CLASS D COMBUSTIBLE METALS OR COMBUSTIBLE METAL ALLOYS (NO picture symbol) CLASS K FIRES IN COOKING APPLIANCES THAT INVOLVE COMBUSTIBLECOOKING MEDIA vegetable or animal oils and fatsTYPES OF EXTINGUISHERS CLASS ACLASS A:BCLASS A:B:CCLASS A:CCLASS B:CCLASS DCLASS A:K 2WHERE TO USEHOW TO USEALL AMEREX FIRE EXTINGUISHERS COMPLY WITH THE RECOMMENDATIONS OF THE NATIONAL FIRE PROTECTION ASSOCIATION AND ARE TESTED AND RATED BY UNDERWRITERS LABORATORIES OR FM GLOBAL TO ANSI / UL STANDARDS. ALL EXTINGUISHER NAMEPLATES CONTAIN THE NECESSARY HMIS INFORMATION TO COMPLY WITH NATIONAL AND LOCAL OSHA REQUIREMENTS.WATER & AFFF ATC 3DISCHARGE TIME (SEC.)INCLUDED BRACKET W E T C H E M I C A L 4WATER MIST 5RUGGED 6 Year Manufacturer’s Warranty Stored Pressure Design Dependable Drawn Steel Cylinders Durable High Gloss Polyester Powder Paint All Metal Valve Construction Temperature Range -40°F to 120°F ENVIRONMENTALLY ACCEPTABLE EPA approved “Clean Agent” for Class A, B and C hazards Low GWP (Global Warming Potential)Low ODP (Ozone Depletion Potential)MINIMUM CONFINED SPACE REQUIREMENTS (CU. FT.)FAA APPROVED MODELINCLUDED BRACKET H A L O T R O N ™Amerex Corporation6H A L O T R O N ™ IHALON 1211 7is discharged as a white cloud of “snow” which smothers a fire by eliminating oxygen. It is effective for Class B flammable liquids and is electrically non-conductive. Carbon Dioxide is a clean, non-contaminating, odorless gas.AVAILABLE IN 50 / 100 lb. WHEELED EXTINGUISHERSC A R B O ND I O X I DE 8Model322NMNON-MAGNETICMODELS 332 331322 330 Manufactured and Tested to ANSI/UL Standards Complies with NFPA 10 Standard ISO-9001 / ISO-14001 Certified UL LISTED DISCHARGE TIME (SEC.)INCLUDED BRACKET Non-Magnetic model available (Model 322NM - Tested to 11.7 Tesla)CLASS D 9A B C D R Y C H E M I C A L 10Aluminum ValveREGULAR DRY CHEMICAL 11P U R P L E K D R Y C H E M I C A L12HIGH PERFORMANCE Dry Chemical 13REGULAR REGULAR PURPLE K 7217611020HOSE & NOZZLE 20B:C 60B:C 20B:C 19.53919.511201.15 1.13 1.1515-2515-2515-2520½2420½ portable fire extinguishers for applications where discharge rates exceeding one pound per second are required as specified in NFPA 10. These extinguishers utilize the same hardware and are manufactured to the same U.L. specifications as Amerex compliance rated products.H I G H F L O W14HIGH FLOW - Exceeds 1 lb. per second discharge rateMODELS (10 LB)720721722D r y C h e m i c a lWATER & FOAM CHARGESRECHARGE AGENTS Charge 502/504, 23 oz. bottle AFFF ATC – Model 250, 252 & 254Note: Charge 502/504 is backwards compatible with previous models.Charge 506B-2, two 2½ gal. bottles Loaded Stream/Anti-Freeze – Model 240Charge 506B-55, 55 gal. drum Loaded Stream/Anti-Freeze - Model 240Charge 534, 2-5/16 gal. pail AFFF ATC – Model 630 WheeledSPECIALTY FOAMS FOR FIRE FIGHTING EQUIPMENT3% AFFF Foam Concentrate - 5 Gallon PailsClass “A” Foam Concentrate - 5 Gallon Pails3 X 3 ATC Foam Concentrate - 5 Gallon PailsWET CHEMICAL CHARGESCharge 530-2, two 6 liter bottles – Model B260Charge 660-2, two 2½ gal. bottles – Model B262WATER MIST CHARGESCharge 670-2, two 1¾ gal. bottles – Model B270NMCharge 671-2, two 2½ gal. bottles – Model B272NMHALOTRON™I CHARGESCharge 890, 35 lb. cylinderCharge 891, 80 lb. cylinderCharge 892, 200 lb. cylinderCLASS D DRY POWDER CHARGESCharge 543, 35 lb. pail Graphite (G-Plus)Charge 532, 300 lb. drum Graphite (G-Plus)[Graphite applied to a metal fire using scoop or shovel]Charge 557, 30 lb. pail Sodium Chloride (Super D) – Model B570 & 680Charge 545, 50 lb. pail Sodium Chloride (Super D) – Model B570 & 680[Sodium Chloride (Super D) may also be dispensed by a scoop or shovel}Charge 548, 50 lb. pail Copper (Navy 125S) – Model B571 & 681ABC DRY CHEMICAL CHARGESCharge 552, 25 lb. pailCharge 550, 50 lb. pailCharge 555, 50 lb. pail – Model B402, IS, VSSCharge 540, 40 lb. cartonCharge 509, 400 lb. drumREGULAR DRY CHEMICAL CHARGESCharge 512, 50 lb. pailCharge 511, 400 lb. drumPURPLE K DRY CHEMICAL CHARGESCharge 553, 25 lb. pailCharge 515, 50 lb. pailCharge 517, 400 lb. drum15B R AC K E T T Y P E S16Wall Hanger BracketsVehicle / Marine / Aviation BracketsHeavy Duty Box Type Vehicle Brackets(Red Brackets are Galvanized)845 817 818 817S 818S 845S 821 821S 861H 808 89604834 01521 05525 09582 09581 16591222900546 0575 057701007 (Red)14315 (NM)807 809 812 809G 810G 811G 811 810 / 810NM 810CG (USCG) 895868 - 6”, 8”, 10”, 12”872 - 6 (6” to 8”)860 862 864Heavy Duty Dolly Cart Heavy Duty RubberStrap Brackets859Bracket Adapters16536* 16538* 16537* Galvanized“I” Beam Brackets Exterior & Interior16594 16598 16596872 - 10 (10” to 12”)17737 (NM)22885 (NM)87420lb. Cartridge Operated/Stored Pressure6 & 10 lb. Wall Strap Type889889HB 846Horn Holder - CO 2(810 or 811 Bracket)0142706584BRACKET REFERENCE 17DRY CHEMICAL STORED PRESSURE Models 495, 496, 49750 lb. Dry ChemicalModels 573, 574, 575, 690HIGH PERFORMANCE 125 / 250 lb. Dry ChemicalModels 488, 489, 490125/150 lb. Dry ChemicalDRY CHEMICAL NITROGEN CYLINDER OPERATEDModels 467, 468, 469125/150 lb. Dry Chemical Models 450, 451, 452, 452OS 125/150 lb. Dry ChemicalModels 470, 471, 472125/150 lb. Dry Chemical Models 491, 492, 493, 493OS 300/350 lb. Dry ChemicalModel 33350 lb. Carbon DioxideModel 334100 lb. Carbon DioxideModel 63033 gal. FFFP Foam Model 680R 150 lb. Sodium Chloride Model 681 250 lb. CopperCARBON DIOXIDE CLASS D FOAMThe largest variety of QUALITY wheeled fire extinguishers available anywhere. See Amerex “Wheeled Fire Extinguishers” brochure for more details.HALOTRON ™ IModels B673, B674, B67565 lb. / 150 lb.Halotron™ IWheeled Extinguishers18W H E E L E DNOVEC TM 1230Model 775150 LB. Novec TM 1230Model 325R32.5 gal. Wet ChemicalVehicle Fire Suppression Systems:Amerex vehicle fire suppression systems are manufactured at our facility in Trussville, Alabama and meet the requirements of the “Buy America Act”. Our products are madein the USA so we can provide you with the quality and flexibility your operation demands - when you need The Amerex Small Vehicle System (SMVS) is designed specifically for applications involving front engine vehicles such as Para-Transit, Airport Shuttle buses and other small front engine vehicles. The SMVS kit includes all hardware and components required for a complete turn-key Automatic Fire Suppression System. The electronics portion of the system is made up of a Vehicle Operator Display with Manual Release Push Button, a wiring Interface Module, and two Solid State Heat Detectors. The system is continuously supervised by the system panel which can detect and actuate the system even when the vehicle is not in use.stored-pressure type listed by Underwriter ’s be designed, installedand maintained Maintenance Manual”, N.F.P.A. 96, N.F.P.A. 17A, local codes and ordinances by an Authorized Amerex KP Systems Distributor using factory trained personnel.RESTAURANT SYSTEM:The Amerex “IS” system uses our exclusive ABC (Model 555) dry chemical. ABC dry chemical suppresses more fire, by volume, than any other agent, has quick flame “knock-down” and canhelp to secure Class A fires against re-ignition. Since many hazards involve a variety of fuel sources, our ABC dry chemical, with protection against Class A (wood, paper, pulp), Class B (flammable liquids) and Class C (live electrical equipment) is the agent that is best suited for most Industrial hazards.19SUPPRESSION SYSTEMSAmerex offers a complete line of manual fire fighting large capacity skid systems for industrial and extremeAmerex Corporation7595 Gadsden Hwy. • P .O. Box 81Trussville, AL 35173Ph: (205) 655-3271 Fax: 1-800-654-5980 Int’l Fax: (205) 655-0584 *********************ISO 9001 - QualityISO 14001 - Environmental OHSAS 18001 - SafetyCERTIFIED FIRMFor more information please contact:Quality is Behind the Diamond ®。
初二化学现象英语阅读理解20题1<背景文章>Combustion is a chemical process that occurs when a substance reacts with oxygen to produce heat and light. There are three essential conditions for combustion to take place. First, there must be a fuel. Fuels can be solids, liquids, or gases. For example, wood, gasoline, and natural gas are common fuels. Second, there must be oxygen. Oxygen is necessary for the chemical reaction to occur. Third, there must be a source of ignition, such as a spark or flame.Different substances burn with different characteristics. Some substances burn rapidly and produce a lot of heat and light. For example, gasoline burns very quickly and can cause explosions if not handled properly. Other substances burn more slowly and produce less heat and light. For example, wood burns more slowly than gasoline but can still provide heat for cooking and heating.Combustion has many applications in our daily lives. For example, we use combustion to cook food, heat our homes, and power our vehicles. However, combustion can also cause problems. For example, uncontrolled fires can damage property and endanger lives.1. The three essential conditions for combustion are fuel, oxygen and___.A. waterB. heatC. a source of ignitionD. carbon dioxide答案：C。
火灾的消灭和预防英文翻译In today's society, fire safety has become an increasingly important issue due to the potential for devastating consequences. Fires can cause damage to property, loss of life, and disruption to businesses and communities. Therefore, it is crucial to understand the methods of fire prevention and extinguishing in order to protect ourselves, our homes, and our workplaces.Fire PreventionPreventing fires from occurring in the first place is the most effective way to ensure fire safety. There are several key measures that can be taken to prevent fires:1. Fire risk assessments: Regular assessments should be carried out to identify potential fire hazards and risks in buildings and workplaces. This allows for measures to be put in place to mitigate these risks and prevent fires from occurring.2. Proper storage of flammable materials: Flammable materials such as gasoline, oil, and chemicals should be stored in a safe and secure manner to prevent accidental ignition.3. Electrical safety: Faulty wiring, overloaded circuits, and damaged electrical appliances can all be sources of ignition. Ensuring proper electrical safety measures are in place can help to prevent electrical fires.4. Fire safety training: Educating individuals on fire safety protocols and procedures can help to reduce the risk of fires occurring. This includes training on how to use fire extinguishers, how to evacuate a building safely, and the importance of early detection of fires.5. Smoke detectors and fire alarms: Installing smoke detectors and fire alarms in buildings can provide early warning of a fire, allowing for prompt evacuation and a quicker response from emergency services.Fire ExtinguishingDespite the best efforts at fire prevention, fires can still occur. In such cases, it is essential to have the knowledge and tools to extinguish the fire safely and effectively. There are several methods of fire extinguishing that can be employed, depending on the type and size of the fire:1. Fire extinguishers: Portable fire extinguishers are a common and effective method of extinguishing small fires. Different types of fire extinguishers are designed to tackle different classes of fires, including Class A (ordinary combustibles), Class B (flammable liquids), and Class C (electrical fires). Therefore, it is important to use the correct type of fire extinguisher for the specific type of fire.2. Water and foam: Water and foam are commonly used to extinguish Class A fires, which involve ordinary combustible materials such as wood, paper, and fabric. Water can help to cool the fire and starve it of oxygen, while foam can create a barrier to prevent re-ignition.3. Carbon dioxide: Carbon dioxide extinguishers are effective for Class B and Class C fires, as they displace oxygen and remove heat from the fire. However, it is important to use caution when using carbon dioxide extinguishers, as they can be dangerous in confined spaces due to the risk of suffocation.4. Dry chemical powder: Dry chemical powder extinguishers are suitable for Class B and Class C fires, as they work by interrupting the chemical reaction of the fire and creatinga barrier to prevent re-ignition.5. Fire blankets: Fire blankets can be used to smother small fires, such as those involving cooking oils or clothing. They are also effective for wrapping around a person whose clothing is on fire to extinguish the flames.ConclusionIn conclusion, fire prevention and extinguishing are vital components of fire safety. By taking proactive measures to identify and mitigate potential fire hazards, and by arming ourselves with the knowledge and tools to extinguish fires effectively, we can help to protect ourselves and our communities from the devastating effects of fires. It is essential for individuals, businesses, and communities to prioritize fire safety and to take the necessary steps to prevent and extinguish fires in order to create a safer environment for all.。
a r X i v :a s t r o -p h /0510367v 2 2 J a n 2006Local Ignition in Carbon/Oxygen White Dwarfs –I:One-zone Ignition andSpherical Shock Ignition of DetonationsL.Jonathan DursiCanadian Institute for Theoretical Astrophysics,University of Toronto,60St.George St.,Toronto,ON,M5S 3H8,Canadaljdursi@cita.utoronto.caF.X.TimmesTheoretical Division,Los Alamos National Laboratory,Los Alamos,NM,87545,USAtimmes@ ABSTRACTThe details of ignition of Type Ia supernovae remain fuzzy,despite the importance of this input for any large-scale model of the final explosion.Here,we begin a process of understanding the ignition of these hotspots by examining the burning of one zone of material,and then investigate the ignition of a detonation due to rapid heating at single point.We numerically measure the ignition delay time for onset of burning in mixtures of degenerate material and provide fitting formula for conditions of relevance in the Type Ia ing the neon abundance as a proxy for the white dwarf progenitor’s metallicity,we then find that ignition times can decrease by ∼20%with addition of even 5%of neon by mass.When temperature fluctuations that successfully kindle a region are very rare,such a reduction in ignition time can increase the probability of ignition by orders of magnitude.If the neon comes largely at the expense of carbon,a similar increase in the ignition time can occur.We then consider the ignition of a detonation by an explosive energy input in one localized zone,e.g.a Sedov blast wave leading to a shock-ignited detonation.Building on previous work on curved detonations,we confirm that surprisingly large inputs of energy are required to successfully launch a detonation,leading to required matchheads of ≈4500detonation thicknesses –tens of centimeters to hundreds of meters –which is orders of magnitude larger than naive considerations might suggest.This is a very difficult constraint to meet for some pictures of a deflagration-to-detonation transition,such as a Zel’dovich gradient mechanism ignition in the distributed burning regime.Subject headings:supernovae:general —white dwarfs –hydrodynamics —nuclear reactions,nucleosynthesis,abundances —methods:numerical1.INTRODUCTIONThe current favored model for Type Ia supernovae (SNIa)involves burning beginning as a subsonic deflagration near the central region of a Chandrasekhar-mass white dwarf.Progress has been made in recent years in understanding the middle stages of these events through multiscale reactive flow simulations where the initial burning is prescribed as an initial condition of one or more sizable bubbles already burningmaterial at time zero.However,the initial ignition process by which such bubbles begin burning–whether enormous50km bubbles(Plewa et al.2004)or more physically motivated smaller igniting points(Reinecke et al.2002;H¨oflich and Stein2002;Bravo and Garc´ıa-Senz2003)remains poorly understood.Further,if later in the evolution there is a transition to a detonation(e.g.,Gamezo et al.2004),this ignition process, too,must be explained.Indeed,ignition physics will play a role—by determining the location,number, and sizes of thefirst burning points—in any currently viable SNIa model.However,until very recently(for example,Woosley et al.2004;Garc´ıa-Senz and Bravo2005)very little work has gone into examining the ignition physics of these events.Here we begin examining the ignition process by considering the simplest ignitions possible–that of a single zone–and the possibility of igniting a detonation from a Sedov blast wave launched at a single point.1.1.Ignition Delay TimesAstrophysical combustion,like most combustion(for example,Williams1985;Glassman1996),is highly temperature-dependent;the12C+12C reaction,for example,scales as T12near109K.Rates for the exothermic reactions which define the burning process are generally exponential or near-exponential in temperature(e.g.,Caughlan and Fowler1988).Thus a region with a positive temperature perturbation can sit‘simmering’for a very long time,initially only very slowly consuming fuel and increasing its temperature as an exponential runaway occurs.This is especially true in the electron-degenerate environment of a white dwarf,where the small increases in temperature that occur for most of the evolution of the hotspot will have only extremely small hydrodynamic effects.If fuel depletion and hydrodynamical effects were ignored,the temperature of the spot would become infinite after afinite period of time.This time is called the ignition time,or ignition delay time,or sometimes induction time,τi.After ignition starts,burning proceeds for some length of timeτb.For burning problems of interest,of course,fuel depletion is important,and no quantities become infinite; however,the idea of an ignition delay time still holds(see Fig.1).If the energy release rate for most of the evolution of the burning is too small to have significant hydrodynamical effects,and if the timescale over which burning‘suddenly turns on’is much shorter than any other hydrodynamical or conductive timescales, then the burning of such a hotspot can be treated,as an excellent approximation,as a step function where all energy is released from t=τi to t=τi+τb.In many problems,whereτb≪τi,this can be further simplified to burning occurring only at t=τi.Where such an approximation(often called‘high activation-energy asymptotics’)holds,it greatly simplifies many problems of burning or ignition,reducing the region of burning in aflame to an infinitesimally thin‘flamelet’(Matalon and Matkowsky1982)surface,for instance, or the structure of a detonation to a‘square wave’(Erpenbeck1963).Where this approximation does not hold–such as if slowβ-decay processes are important as bottlenecks for reactions to proceed(e.g.,p-p burning or the CNO cycle)the simplification of burning happening only overτi≤t≤τi+τb often remains useful.Even for the simple case of one zone,ignition delay times are relevant for investigation of ignition in SNIa because it sets a minimum time scale over which an initial local positive temperature perturbation(hot spot)can successfully ignite and launch a combustion wave;other timescales,such as turbulent disruption of the hotspot,or diffusive timescales,must be larger than this for ignition to successfully occur.If the burning occurs in an ideal gas,or in a material with some other simple equation of state,it is fairly easy to write down approximate ignition times for various burning laws.In a white dwarf,however,where1e+092e+093e+094e+095e+096e+09 7e+098e+099e+090 0.005 0.01 0.0150.02 0.0250.03 0.035 0.04 0.045T e m p (K )Time (s)Ignition Delay TimeFig.1.—Temperature evolution for burning a zone at constant pressure with an initial state of X 12C =1.0,T =109K,ρ=5×108g cm −3.Because of the strong temperature dependence,a runaway takes place and most of the burning happens ‘all at once’.the material is partially degenerate or relativistic and the equation of state is quite complicated (Timmes and Swesty 2000),no such closed-form expression can be written.In §2we numerically follow the abundance and thermodynamic evolution of a zone of white dwarf material in order to measure the ignition times as a function of the initial temperature,density,and composition.We follow both constant-density and constant-pressure trajectories.The results are summarized by simple,moderately accurate,fitting formula.In §3we consider the ignition of a detonation through a localized energy release producing a Sedov blast wave,and estimate the amount of energy that must be released for the detonation to successfully ignite.In §4we consider our results in light of likely temperature fluctuation spectra during the simmering,convective phase.2.ONE ZONE IGNITION TIMES2.1.CalculationsWe performed a series of 1-zone calculations for the purposes of measuring ignition times in carbon-oxygen mixtures.For each of these two burning conditions –burning at constant volume and constant pressure –over 3500initial conditions were examined,in a grid of initial densities,temperatures,and initial carbon fraction.The carbon (mass)fractions were in the range 0.4≤X 12C ≤1.0,with the remainder being oxygen (X 16O =1−X 12C ),temperatures of 0.5≤T 9≤7,and densities 0.1≤ρ8≤50,where T 9is the temperature in units of 109K and ρ8is the density in units of 108g cm −3.For burning,a 13-isotope αchain was used (Timmes 1999),and a Helmholtz free energy based stellar equation of state (Timmes and Swesty 2000)maintained the thermodynamic state.The temperature and abundance evolution equations were integrated together consistently,as described in Appendix A.Time evolutions were generated as in Fig.1.To cover the wide range of burning times within each integration,the timestep was increased or decreased depending on the rate of abundance,energy release,and thermodynamic changes.The time interval was varied by up to a factor of two in each timestep,to try to keep the amount of energy released through burning per timestep change of fuel within the range 10−5−10−7.Timesteps failing this criterion wereundone and re-taken with a smaller time interval.The final ignition time,when the simulation was stopped,was defined to be time when 90%of the carbon was consumed,although the time reported was found to be insensitive to endpoint chosen.The code used in this integration,as well as the resulting data,is available at http://www.cita.utoronto.ca/∼ljdursi/ignition/.Over the initial conditions chosen,ignition times varied from 10−14s to 10+8s.A representative contour plot showing the calculated ignition delay times are shown in Fig.2.7.07.58.08.59.09.510.0Log10 densityL o g 10 t e m p e r a t u r eFig.2.—Contour plot of ignition time as a function of initial density and temperature for a constant-pressure ignition of a mixture of half-carbon,half-oxygen by mass.Fitting formula for the ignition delay times under the two burning conditions were determined;the ignition time for constant-pressure ignition can be given approximately asτi,cp (ρ,T,X 12C )=1.15×10−5sec (X 12C ρ8)−1.9f cp (T )(1+1193f cp (T ))(1)f cp (T )=(T 9−0.214)−7.566and that for constant-volume ignitionτi,cv (ρ,T,X 12C )=1.81×10−5sec (X 12C ρ8)−1.85f cv (T )(1+1178f cv (T ))(2)f cv (T )=(T 9−0.206)−7.700where T9is the initial temperature in units of109K,andρ8is the initial density in units of108g cm−3.Thefits are good to within a factor offive between10−9sec and1sec,and to within a factor of 10between10−14sec and100sec.This can be compared to other analytic expressions,for instance the constant-pressure formula from Woosley et al.(2004),τi=15sec 7ρ9 3.3(3) which,as shown in Fig.4,is an excellent approximation over a somewhat more narrow range ofconditions. Fig.3.—Fit results vs.calculated results for constant-pressure(left)and constant-volume(right)ignition delay times,for the full range of densities(0.1≤ρ8≤50),temperatures(0.5≤T9≤7),and carbon mass abundances(0.4≤X12C≤1.0)considered.Fig.4.—Woosley et al.(2004)ignition time results vs.calculated results for constant-pressure ignition delay times for a mixture half-carbon half-oxygen by mass(X12C=0.5),over a truncated range(1≤ρ8≤50), (0.5≤T9≤1.5).Which of the two cases(constant volume or constant pressure)are appropriate will depend on comparing the ignition time with the relevant hydrodynamical timescale—in particular,the sound-crossing time of the region undergoing ignition.If the region is small enough that many sound crossing times occur during the ignition,then the constant-pressure value is appropriate;if ignition occurs in much less than a crossing time,the constant-volume value is appropriate;intermediate timescales will result in intermediate values.In the case of turbulent ignition of aflame,presumably it is the constant-pressure time which will be most relevant. In any case,due to the degeneracy of the material in the density and temperature ranges considered here, the computed ignition times(or thefits)rarely differ between the two cases more than50%.2.2.Effect of MetallicityMost of the initial metallicity of main-sequence star comes from the CNO and56Fe nuclei inherited from its ambient interstellar medium at birth.The slowest step in the hydrogen-burning CNO cycle is proton capture onto14N.This results in all the CNO catalysts piling up into14N when hydrogen burning on the main sequence is completed.During helium burning,all of the14N is converted into22Ne.As a proxy for investigating the effects of metallicity in ourα-chain based reaction network,we consider the ignition of a X12C=0.5constant-pressure ignition while increasing the fraction of20Ne(and thus decreasing the abundance of oxygen).We’ll verify this surrogate by using22Ne in larger networks.The effects of increasing X20Ne from0to0.05,and then further to0.1and0.2,is shown in Fig.5. Addition of even fairly modest amounts of neon can significantly(20–30%)reduce the ignition times for much of the thermodynamic conditions evaluated here.The reduced ignition times are found to result from a larger energy release from burning over the entire integration range.To understand the increase in the energy deposited by burning,consider theα-chain reactions which dominate burning in this regime and are modeled by the‘aprox13’network as:12C+12C→20Ne+α+13.933MeV12C+α→16O+7.162MeV16O+α→20Ne+4.734MeV(4)20Ne+α→24Mg+9.312MeV24Mg+α→28Si+9.984MeV.Given an initial mixture of12C,16O,and20Ne,it is the carbon burning reaction12C+12C which happens first.The resultingα-particle can capture onto carbon or any heavier element in theαchain.Unless that chain is already populated,then the(very exothermic)neon capture and allflows to still heavier nuclei are choked offuntil enough20Ne and24Mg are generated through burning.Adding even quite modest amounts of neon to the initial mixture allows moreα-chain reactions to promptly occur during carbon burning.The plots in Fig.6show the abundance evolution ofα-chain elements during constant-density burning atρ8=10,T9=1,X12C=0.5,and an initial neon abundance of zero and0.05.The inclusion of5%neon by mass greatly speeds the production of heavier intermediate-mass elements,and thus the exothermicity of the burning,reducing the ignition time.To confirm that this effect is not artificially enhanced by using anα-chain reaction network,and to quantitatively verify the ignition times produced by the aprox13network used here,we compared the ignition times at two(ρ,T)points and varying neon abundance with those produced by reaction networks containing 513and3304isotopes.The results are shown in Table1We see that not only are the times computed with the smaller network quantitatively in good agreement with the larger networks(within10%for the10-2010-1010010101020ignition time, X( 22Ne) = 0, (s)-0.20-0.15-0.10-0.050.000.05% d i f f e r e n c e ( 22N e = 0.05 - 22N e = 0.00)Log 10 densL o g 10 t e m pLog 10 densL o g 10 t e m pLog 10 densL o g 10 t e m pFig. 5.—The difference in ignition time for a constant-pressure ignition of X 12C =0.5,X 16O =0.5when some of the Oxygen is replaced by Neon-20.On the top left is shown the fractional difference in ignition time with the addition of X 20Ne =0.05as a function of the ignition time with X 20Ne =0.0.On the top right,bottom left,and bottom right are contour plots in ρ−T space of the percent difference in ignition time with X 20Ne =0.05,0.1,0.2,respectively.The ignition time for the base case is shown in Fig.2.lower-temperature case,and within 25%for the higher case),but the trends are similar.The same trend is apparent when 22Ne,unavailable in the α-chain network,is used instead of 20Ne.The trend is in fact stronger with 22Ne because of additional flow paths that become available.While the above has demonstrated the active role neon plays in the ignition process,its effect is much smaller than that of carbon,which is the primary source of fuel in this burning process.As a result,in the more realistic case when an increase in neon comes at the expense of both carbon and oxygen,this effect is reduced (for small neon fractions)or completely reversed (for moderate neon fractions).This is shown,for instance,in Fig.7.In this case,increased metallicity of the progenitor system has the opposite effect;it makes the ignition time significantly longer for hotspots in the resulting white dwarf.2×10-23×10-24×10-25×10-26×10-27×10-210-810-710-610-5.0001.001.01.11M a s s F r a c t i o nTime (s)HeHe He HeHeHe He He He He He He He He He He He HeHe He He He He He He He He He He He C C CCCC C C C C C C C C C C O O O O OO O O O O NeNe NeNe Ne Ne Ne Ne Ne Ne Ne Ne Ne Ne Ne Ne Ne Ne Ne Ne Ne MgMg MgMgMg Mg Mg Mg Mg Mg Mg MgMg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Si Si SiSiSi Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si 2×10-23×10-24×10-25×10-26×10-27×10-210-810-710-610-5.0001.001.01.11M a s s F r a c t i o nTime (s)HeHe HeHeHe He He He He He He He He HeHe He He He He He He He He He He He He He He He He CC C C C C C C C C C C C O O O O O O O O O O NeNe Ne NeN e Ne Ne Ne Ne Ne Ne Ne Ne MgMg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg Mg SiSiSi Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Si Fig. 6.—Mass fraction evolution in constant-density burning,with an initial state of ρ8=10,T 9=1,X 12C =0.5,with X 20Ne =0.0(left)and X 20Ne =0.1(right).The burning here was calculated with a 513-isotope network.Because of the removal of the α-chain bottleneck at neon on the right,burning proceeds faster and the generation of higher intermediate-mass elements is raised by orders of magnitude at early times.3.APPLICATION:IGNITION OF A DETONATION3.1.Detonation StructureDetonation waves are a supersonic mode of propagating combustion.A shock wave heats up material,which then ignites,releasing energy which further powers the shock.(See,for instance,textbooks such as Glassman 1996;Williams 1985).There are,broadly,four states in a detonation:the unshocked material;the shocked material immediately behind the shock;an induction zone,where the heated material slowly begins burning and then the reaction zone,where the bulk of the exothermic burning takes place.Unsupported,self-sustaining detonations can be of the Chapman-Jouget (CJ)type,where at the end of the reaction zone the flow becomes sonic,or of the pathological type,where the sonic point occurs within reaction zone,decoupling the flow downstream of the sonic point from the shock.Pathological detonations can occur in material where there are endothermic reactions or other dissipative or cooling effects,and may have speeds slightly higher (typically by a few percent)than the CJ speed.Detonations within highly degenerate white-dwarf material (ρ8>0.2)are of the pathological type (Khokhlov 1989),largely because some regions of the flow behind the detonation can have significant amounts of endothermic reactions,violating the assumptions of the CJ structure.Because in the case of a pathological detonation some fraction of the reactions powering the detonation are decoupled from the shock,calculating the speed of a pathological detonation requires detailed integration of the detonation structure,rather than simply using jump conditions.For either kind of detonation,one can estimate where most burning occurs with shock speed D (which,even in non-CJ case,can be estimated with CJ speed)and τi ;l i =Dτi is the position behind the shock at which the induction zone ends and rapid burning takes place.In the case of a detonation into a very low-density,cold material,the material immediately behind the shock will still not burn significantly until a length of time equal to the ignition time passes,resulting in a ‘square wave’detonation.For conditions relevant to near the core of a white dwarf,however,the post-shock fluid will typically have temperatures on order T 9≈5–that is,temperatures which are already near theLog 10 densL o g 10 t e m pLog 10 densL o g 10 t e m pFig.7.—As in Fig.5,the difference in ignition time for a constant-pressure ignition of X 12C =0.5,X 16O =0.5when (left)a mass fraction of 0.005of each of the carbon and oxygen is replaced by Neon-20and (right)when 0.05of each is replaced by Neon.Note that in this case,for X 20Ne =0.1,with the exception of a small region in (ρ,T )the ignition time is increased by the same magnitude that it is decreased in the case when all of the neon comes from oxygen,e.g.the X 12C =0.5,X 16O =0.4,X 20Ne =0.1case of Fig 5in the bottom right panel.maximum temperature which will be obtained by burning.Even in these cases,this estimate of l i provides a good measure of the thickness of the detonation structure behind the shock,as is shown in Fig 8where it measures the position of maximum burning.3.2.Ignition of a Spherical DetonationOne mechanism for ignition of a detonation by a hotspot is an initial rapid input of energy which leads to a Sedov blast wave;the material shocked by the outgoing spherical blast ignites,and as the outgoing wave slows,a steady outgoing detonation results.A steady detonation cannot form until the outgoing shock wave speed drops to the detonation velocity detonation,or else the energy released by reactions behind the blast wave will not be able to ‘catch up’to the outgoing shock to drive it.On the other hand,if the shock drops significantly below the detonation speed before ignition takes place,not enough material will be burning per unit time to sustain a detonation wave.We denote the position of the shock when it reaches the detonation speed from above as R D .Naively,the condition for successful detonation ignition would be that R D l i ,since a detonation structure with width of order l i must be set up before the shock speed becomes too slow;a more sophisticated derivation of this criterion can be found in Zeldovich et al.(1956).However,experimentally this is known to be far too lenient a condition for terrestrial detonations and R D must be orders of magnitude larger than l i (Desbordes 1986).This has also been empirically seen in the context of astrophysical detonations (e.g.,Niemeyer and Woosley 1997).This has been explained by,for instance,He and Clavin (1994).Curvature has a significant nonlinear effect on the structure of a detonation —even more so than on the structure of a flame (e.g.,Dursi et al.2003)because the curvature directly effects the burning region rather than merely the preconditioning (diffusion)region.He and Clavin (1994),looking at a pseudo-steady calculation of a detonation with curvature,find that for a steady detonation to exist requires the curvature to be extremely small.The condition found by the authors requires R D ≈44γ2/(γ2−1)βZ l i ,where γis the polytropic index of the ideal gas and βZ0 1e+272e+27 3e+27 4e+27 5e+27 6e+27 7e+27 8e+27 9e+271e+28 00.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.090.1E n e r g y R e l e a s e (e r g /g /s )Position behind shock (cm)Pred. width-0.0010.0000.0010.0020.003Position behind shock (cm)0.00.20.40.60.81.01.2P r e s , E n e r g y R e l e a s ePred. WidthFig.8.—Two examples of estimating the detonation thickness,l i =v s τi in a detonation.On the left,plotted energy release rate from nuclear reactions behind the shock of a leftward-traveling ZND detonation into a pure-carbon quiescent medium of ρ8=1,T 9=0.05.The shocked state is ρ8=2.97,T 9=4.2,and the incoming fuel velocity behind the shock is 4.0×108cm s −1.For the shocked material,the predicted ignition time is ≈3×10−11sec.Even in this case,where the shocked temperature is so high that significant burning occurs immediately,and the ‘square wave’detonation structure does not apply,the predicted l i =1.2×10−2cm correctly matches the peak of the reaction zone.On the right,pressure (top)and energy release rate (bottom),plotted relative to their maximum values,behind a leftward-traveling slightly overdriven detonation into the same material as in the previous figure,calculated by the hydrodynamics code Flash (Fryxell et al.2000;Calder et al.2002).The line above the plotted quantities shows the predicted l i calculated with the observed values in the shocked state.represents the temperature sensitivity of the burning law;for the reactions and temperatures of interest in astrophysical combustion,βZ ≈10−15(Dursi et al.2003).Using γ=4/3to describe the highly degenerate material near the centre of the white dwarf,this would give R D ≈1000−1500l i .While in many cases using a polytropic ideal gas equation of state to describe degenerate white dwarf material can be an excellent approximation,in combustion phenomenon where the burning rate is highly temperature dependent it is problematic,making the above result unsuitable.Further,the authors assume a CJ detonation,as opposed to the pathological detonation that occurs at high densities in a white dwarf.This makes a straightforward application of the results of He and Clavin (1994)to our problem of interest difficult.Given the complexity of the partially degenerate equation of state in the white dwarf,re-deriving the analytic results for this application would be difficult.However,the detailed effect of curvature on detonations in white dwarfs has already been studied in a different manner,by Sharpe (2001).In this approach,the velocity eigenvalue for the detonation –which depends sensitively on the detonation structure –is calculated using a shooting method to numerically integrate the structure of a pathological detonation to the sonic point.A range of possible detonation velocities is input,and then repeatedly bisected as the detonation structure with a fixed given curvature term is integrated assuming the current detonation velocity.The result is the velocity-curvature relation for a detonation into a given ambient material,and as a byproduct,the relationship between the thermodynamic structure (at least up to the sonic point)and the curvature for the curved detonation.We follow the method of Sharpe (2001),also described in Appendix B,and measure the maximum sustainable spherical curvature of a detonation using the same equation of state and burning network asused in the ignition time study.An example of the detonation-speed versus curvature relation is given in Fig.9.Beyond some maximum curvature κmax ,no steady-state unsupported detonation can exist;thus inthe case of a spherical detonation,for a steady detonation to successfully ignite,R D >κ−1max .1.1e+091.11e+091.12e+091.13e+091.14e+091.15e+091.16e+09 1.17e+091.18e+09-0.00050 0.0005 0.0010.0015 0.002 0.0025 0.003 0.0035S t e a d y S t a t e V e l o c i t y (c m /s )Curvature (1/cm)Fig.9.—Example of detonation speed vs.curvature,for a detonation into a quiescent medium of ρ8=1,T 9=0.05,X 12C =0.5,X 16O =0.5.We calculated the detonation speed versus curvature relation for 0.5≤ρ8≤20and 0.25≤X 12C ≤1.0.The unshocked material was set to a temperature of T 9=0.05,although the results were seen to be insensitive to this value.Our results are shown in Fig.10and Table 2.The code used to perform the calculations is available at http://www.cita.utoronto.ca/∼ljdursi/ignition.The estimated detonation thickness and a comparison with κmax is given in Table 3.As compared with the He and Clavin (1994)results of R D 1000−1500l i ,we find R D 3000−6000l i .We can approximately summarize our results for the detonation velocity and the maximum curvature of these curved detonations:D =v (κ=0)=1.158×109cm s −1X 12C0.52.869ρ1.2728(6)。
