外文文献及翻译_Introductions to temperature control and PID controllers

扩展温度英语作文Temperature is a fundamental concept in physics, defining the average kinetic energy of the particles in a substance. It plays a crucial role in various aspects of our daily lives and scientific studies. In this essay, we will delve into the significance of temperature, its measurement, and its impact on the environment and human activities.Firstly, let's consider the importance of temperature in everyday life. The temperature of the air affects our comfort levels and can influence our choice of clothing, the type of food we consume, and even our mood. For instance, during colder months, people tend to prefer warm beverages and hearty meals, while in warmer climates, lighter fare and cooling drinks are more appealing.Moving on to the measurement of temperature, there are several scales in use, each with its own advantages. The most common scales are Celsius, Fahrenheit, and Kelvin. The Celsius scale is widely used in most of the world, with water freezing at 0°C and boiling at 100°C at stand ard atmospheric pressure. The Fahrenheit scale, primarily used in the United States, has water freezing at 32°F and boiling at 212°F. Kelvin, on the other hand, is an absolute scale that starts at absolute zero, the point at which all molecular motion stops.Temperature also has a significant impact on the environment.Global warming, for example, is a critical environmentalissue that involves the rise in Earth's average temperature due to the increase in greenhouse gases. This rise in temperature can lead to the melting of polar ice caps, rising sea levels, and changes in weather patterns, all of whichhave profound implications for ecosystems and human societies.In scientific research, temperature is a key variable in many experiments and studies. It can affect chemical reactions,the growth of microorganisms, and the behavior of materials. For example, in metallurgy, the temperature at which metalsare heated and cooled can determine their strength and ductility.Furthermore, temperature plays a role in technological advancements. In fields such as electronics, the operating temperature of components can affect their performance and lifespan. In medicine, precise temperature control isessential for procedures like cryotherapy and hyperthermia.In conclusion, temperature is a multifaceted concept that extends far beyond a simple measure of heat. It influencesour daily lives, affects the environment, and is integral to scientific research and technological development. Understanding temperature and its effects is essential forboth personal well-being and the advancement of knowledge.。

英语关于温度的作文Title: Exploring the Dynamics of Temperature in English。

Temperature is a fundamental aspect of our everyday lives, influencing everything from the clothes we wear tothe food we eat and the activities we engage in. In this essay, we delve into the intricacies of temperature, examining its significance, effects, and implicationsacross various contexts.To begin with, temperature serves as a crucialindicator of environmental conditions. Whether it's the warmth of a sunny day or the chill of a winter evening, temperature profoundly influences our perceptions and experiences of the world around us. Moreover, temperature plays a pivotal role in determining the distribution offlora and fauna, shaping ecosystems and biodiversity patterns.In human society, temperature holds immense practicalimportance. It directly impacts agricultural practices, influencing crop growth, livestock health, and food production. Additionally, temperature variations affect energy consumption patterns, with hotter climates often necessitating increased use of air conditioning and refrigeration systems. Furthermore, temperaturefluctuations can have significant implications for public health, contributing to heat-related illnesses and exacerbating existing medical conditions.One of the most pressing issues related to temperature in contemporary times is climate change. Human activities, such as the burning of fossil fuels and deforestation, have led to a rapid increase in global temperatures, resulting in a myriad of environmental consequences. These include rising sea levels, extreme weather events, and disruptions to ecosystems. Addressing climate change requires concerted global efforts to reduce greenhouse gas emissions and transition towards sustainable practices.In scientific terms, temperature is a measure of the average kinetic energy of particles in a substance. Thisconcept is central to understanding the behavior of matter across different states – solid, liquid, and gas. Changesin temperature can lead to phase transitions, such as melting, freezing, evaporation, and condensation, whichhave profound implications for various natural processesand industrial applications.The study of temperature is not confined to Earth alone. Scientists explore temperature dynamics across the vast expanse of space, from the intense heat of stars to thefrigid depths of interstellar space. Understanding temperature variations in celestial bodies informs our knowledge of cosmology and the evolution of the universe.On a more personal level, individuals often have their own subjective experiences and preferences regarding temperature. Some may relish the warmth of summer days,while others find solace in the crispness of winter air. Cultural and geographical factors also influence people's tolerance for different temperature ranges, as evidenced by the diverse clothing styles and heating practices found across the globe.In conclusion, temperature is a multifaceted phenomenon with far-reaching implications for both the natural world and human society. Its effects span across various domains, from agriculture and energy to health and climate. As we navigate the complexities of temperature dynamics, it becomes increasingly clear that understanding andmitigating its impacts are essential for ensuring a sustainable future for generations to come.。

介绍温度句式英语作文Introduction to Temperature。

Temperature is a measure of the degree of hotness or coldness of an object. It is an important physical quantity that affects our daily lives. In this essay, we will explore the different types of temperature scales, the factors that affect temperature, and the applications of temperature in various fields.Types of Temperature Scales。

There are three main temperature scales used in the world today: Celsius, Fahrenheit, and Kelvin. The Celsius scale, also known as the centigrade scale, is based on the freezing and boiling points of water. The freezing point of water is 0 degrees Celsius (°C), and the boiling point is 100°C. The Fahrenheit scale, developed by the German physicist Daniel Gabriel Fahrenheit, is based on the freezing and boiling points of a mixture of salt, ice, andwater. The freezing point of this mixture is 32 degrees Fahrenheit (°F), and the boiling point is 212°F. The Kelvin scale, named after the British physicist William Thomson, is based on the absolute zero point, which is the temperature at which all matter has zero thermal energy. The Kelvin scale is used in scientific and engineering applications.Factors that Affect Temperature。

温度控制系统中英文对照外文翻译文献温度控制系统中英文对照外文翻译文献温度控制系统中英文对照外文翻译文献(文档含英文原文和中文翻译)译文:温度控制系统的设计摘要：研究了基于AT89S 51单片机温度控制系统的原理和功能，温度测量单元由单总线数字温度传感器DS18B 20构成。

该系统可进行温度设定，时间显示和保存监测数据。

如果温度超过任意设置的上限和下限值，系统将报警并可以和自动控制的实现，从而达到温度监测智能一定范围内。

基于系统的原理，很容易使其他各种非线性控制系统，只要软件设计合理的改变。

该系统已被证明是准确的，可靠和满意通过现场实践。

践。

关键词：单片机；温度；温度关键词：单片机；温度；温度I. 导言温度是在人类生活中非常重要的参数。

在现代社会中，温度控制（TC TC）不仅用于工业生产，还广泛应用于其它领域。

随着生活质量的提）不仅用于工业生产，还广泛应用于其它领域。

随着生活质量的提高，我们可以发现在酒店，工厂和家庭，以及比赛设备。

而比赛的趋势将更好地服务于整个社会，因此它具有十分重要的意义测量和控制温度。

度。

在AT89S51AT89S51单片机和温度传感器单片机和温度传感器DS18B20DS18B20的基础上，系统环境的基础上，系统环境温度智能控制。

温度可设定在一定范围内动任意。

该系统可以显示在液晶显示屏的时间，并保存监测数据，并自动地控制温度，当环境温度超过上限和下限的值。

这样做是为了保持温度不变。

该系统具有很高的抗干扰能力，控制精度高，灵活的设计，它也非常适合这个恶劣的环境。

它主要应用于人们的生活，改善工作和生活质量。

这也是通用的，因此它可以方便地扩大使用该系统。

因此，设计具有深刻的重要性。

一般的设计，硬件设计和软件系统的设计都包括在内。

设计，硬件设计和软件系统的设计都包括在内。

II. 系统总体设计该系统硬件包括微控制器，温度检测电路，键盘控制电路，时钟电路，显示，报警，驱动电路和外部RAM RAM。

中英文文献翻译-发动机冷却系统1S u m m a r i z eOutli ne use s a m ore compact desi gn along w ith the engi ne and has in a bi g w ay, the engi ne produces the w aste he at de nsity also obvi ousl y i ncre ases al ong with it. S ome essenti al re gi ons, i f around a row of ty re v al ve radi ate s the questi on to have fi rst to conside r, the cooli ng sy ste m eve n i f appears the small bre akdow n al so possi bl y to cre ate the di saste r in such re gion conse que nce. The e ngi ne cooli ng sy ste m radi ati on ability gene rall y shoul d sati sfy w he n the engi ne full load radi ati on dem and, be cause thi s ti me e ngine produces the quantity of he at is bi g gest. Howe ve r, w he n parti al l oads, the curre nt capacity w hi ch the cooli ng sy ste m can have the powe r loss, whi ch the w ate r pum ping stati on provi des the re fri ge rant current capacity surpasses nee ds. W e hoped starts the starting ti me to be as far as possi ble short. B e cause engi ne ti me di scharges poll utant m ore , the oil consum pti on is also bi g. T he cooling sy stem structure has a m ore tre mendous infl uence to the e ngi ne cold starting ti me.2C h a r a c t e r i s t i c s of m od e r n e n g in e c oo l in g s y s t e mM ode rn e ngi nes serie s characteri sti c tradition cooling sy ste m function reli abl y prote cts the engi ne, but also shoul d have the functi on w hi ch the i mprove ment fuel e conom y and reduces discharges. There fore, the m odern cooli ng sy stem must sy nthesize under the consi deration the factor: Engi ne inte rior fri cti on l oss; C ooli ng syste m w ater pump powe r; B urning boundary conditi on, li ke combusti on cham ber tem pe rature, complete density , complete te mpe rature . The advance d cooling sy ste m uses sy ste m atize d, the modular desi gn method, the ove rall pl an conside re d e ach i nfl ue nce factor, cause s the cooling sy stem both to guarantee the e ngi ne norm al w ork, and enhance s the engi ne e ffi cie ncy and the reducti on di scharge s.2 .1 T h e t e m p e r a t u r e s se t p o in tTempe ratures hy pothe ses fi ring i n bursts m otive operati ng tem pe rature l i mit value are de cide d by a row of tire v al ve the peri pheral re g i on m axi mum tem perature. T he m ost ide al situation is according to the metal tempe rature but is not the refri gerant te mpe rature control cooling sy ste m, like thi s can prote ct the e ngi ne w ell.B ecause the cooling sy ste m hy pothe sis cooli ng te mpe rature i s by the full l oad ti me m ost is bi g i s the foundati on, there fore, engi ne and cooling sy s tem in parti al l oads ti me is at not too the perfe ct conditi on, w hen urban distri ct travel and l ow spee d travel, can have the hi gh oil consumpti on and di scharge. S upposes the fixe d point through the change re fri ge rant tem perature to be possible to i mprove the engine and the cooling sy ste m in parti al l oads time perform ance. A ccording to a row of ty re v al ve the peripheral re gion tem pe rature li mit v alue, m ay elevate either reduce the re fri ge rant or the metal te mpe rature supposes the fixe d point. Ele v ates or reduced tem pe rature all re spe cti vel y has the characte risti c, this i s decide d the goal w hi ch achie ved to the hope .2 .2 E n h a n c e s t h e t e m p e r a tu r eEnhance s the tem pe rature to suppose the fixe d-point enhance ment operati ng te mpe rature to suppose the fixe d point is one ki nd of com parison the method w hi ch wel come. Enhance s the tempe rature to have m any meri ts, it dire ctl y affects the e ngine l oss and the cooli ng sy stem e ffe ct as well as the e ngi ne di schargi ng form ation. W ill enhance the operati ng te mpe rature to enhance the e ngine M ac re duce the engi ne to rub we ars, reduces the engine fuel oil consum pti on. The rese arch indi cated that, the e ngi ne operating te mpe rature to rubs the l oss to have the ve ry treme ndous i nflue nce. Discharges the te mpe rature the re fri ge rant to enhance to 150 ℃ , causes the cy l i nde r te m perature to ele vate to 195 ℃ , the oil consumption drops 4% -6% . M ai ntains the refri gerant te m perature i n 90 -1 15 ℃ scope, causes the engine m achine oil the m axi mum te mpe rature is 14 0 ℃ , then oil consumpti on in partial loads ti me drops 10% . Enhances the operati ng te mpe rature al so obvious infl ue nce cool ing sy ste m the pote ncy. Enhances the refri ge rant or the metal te mpe rature can i mprove the engi ne and di spe rse the ste am he at transfer transmission the effe ct, re duce s the re fri g erant the speed of fl ow, reduces the w ate r pump the rate d power, thus re duce s the engi ne the pow e r di ssi pation. In addition, m ay sele ct the diffe rent method, furthe r re duces the re fri ge rant the speed of flow .2 .3 R e d u c e th e t e m p e r a t u r e s se t p o i n tR educed te m peratures suppose the fi xed point to reduce the cooli ng sy stem the ope ra ti ng tem perature to be possi ble to e nhance the engine charge e ffi ciency , re duce s the inlet te mpe rature. Thi s to the com bustion proce ss,the fuel oil effi cie ncy and discharges adv antage ousl y . T he reduced tem perature supposes the fi xed poi nt to be all owed to save the engine m ove me nt cost, enhances the part servi ce li fe. The rese arch indi cate d, if the cy linde r he adte mpe rature re duce s to 50 ℃ , the i gnition angle of advance m ay 3 ℃ A but not have the engi ne knock ahe ad of time , the charge effi cie ncy enhances 2 % , the e ngi ne ope rati onal factor i mprove ment, is hel pfulto the opti mize d com pre ssi on rati o and the paramete r choi ce, obtai ns the bette r fue l oil effi ciency anddischarges the pe rform ance.2 .4 P r e c i se c oolin g sy s t e mPre cise cooling sy stem s pre ci se cooli ng sy ste m mainl y m ani fests i n the cooli ng j acket s tructural desi gn and in the refri gerant spee d of fl ow desi gn. In pre cise cooling system, hot e ssenti al are a, i f around a row of ty re valve, the re fri ge rant has an gre ate r spee d of fl ow , the he at transfer effi cie ncy is hi gh, the refri gerant gradie ntof tem pe ra ture changes sli ghtl y . S uch e ffe ct comes from to re duce these pl ace re fri ge rant channels the l ate ral secti on, e nhances the spee d of fl ow, re duce s the current capacity . T he pre ci se cooli ng sy ste m desi gn ke y lies in the de termi nation cooli ng j acke t the size, the choi ce m atch cooling w ate r pum p, guaranteed the sy ste m the radi ati on ability can satisfy w hen the l ow spee d bi g load essenti al re g i on operating te m perature de m and. The engi ne refri gerant spee d of fl ow range of vari ati on is quite bi g , from ti me 1 m /s to m axi mum w ork rate time 5 m /s. The re fore shoul d conside re d the cooli ng j acket and the cooling sy stem whole that, m utuall y suppleme nted, displ ay bi gge st pote nti al. The rese arch indi cate d that, uses the pre cise cooling sy stem , i n the engi ne entirew ork rotational spee d scope , the refri gerant curre nt capacity m ay drop 4 0% . C ove rs the cool ing j acket to theai r cy linde r the pre cise de si gn, m ay m ake the ordi nary spee d of fl ow to e nhance from 1 .4 m /s to 4 m /s , gre atl y enhances the cy l inde r cove r or cap the rm al conducti vity , cy l inde r cove r or cap metal te mpe rature drop to60 ℃ .2 .5 Div e r g e n c e s t y p e s c oolin g s y s t e mDiverge nce s ty pe s cooli ng sy ste m dive rge nce ty pe cooli ng sy stem for othe r one ki nd of cool ing sy ste m. In this ki nd of cooli ng sy ste m, the hi ne oil te mpe rature , will cy l i nde r cove r or cap frie ndl y cy li nde r body cools by respective return route , the cyl inder cover or cap friendl y cyli nder body has the di ffe rent tem perature. T hedive rge nce -li ke cooli ng sy ste m has the uni que supe ri ority , m ay cause e ngi ne e ach part to suppose the fixe d-point w ork at the m ost supe rior tem pe rature. The cooli ng sy ste m ove rall effi cie ncy achieves i n a bi g w ay . Each cooling return route w il l suppose unde r the fixe d poi nt or the speed of fl ow i n the diffe rent cooli ng tempe rature works, w i ll cre ate the i deal engi ne te mpe rature distri bution. T he i de al e ngi ne hot acti ve status isthe cy linder he ad te mpe rature lowe r but the ai r cyl inder body te m perature rel ative is hi ghe r. T he cy linde r he ad tempe rature is l ow e r m ay e nhance the charge e ffi ciency , i ncre ases. The tem perature is l ow also gre atl y m ay promote completel y to burn, re duces C O, HC and the NOx form ation, a lso enhance s the output. T he hi gher ai rcy linde r body tem perature can re duce the fri cti on to lose, di re ctl y im proves the fuel oil effi ciency , i ndire ctl y reduces i n the cy li nde r the peak val ue pressure and the tem pe rature. T he dive rge nce ty pe cool ing sy ste m m ay cause the cy linder cove r and the cy linde r body tem pe rature di ffe rs 1 00 ℃ . T he cy l inde r te mpe rature m ay re achas hi gh as 15 0 ℃ , but the cy li nde r cove r tem perature m ay re duce 50 ℃ , re duce s the cy linde r body to rub l oses, reduces the oil consum ption. The hi ghe r cy linde r body tem perature causes the oil consum pti on to re duce4% -6% , w hen parti al l oads HC reduces 20 % -3 5% . W hen the dampe r all opens, the cy li nde r cove r and the cy linde r body tem perature supposes the de finite v al ue to be possi ble to move to 50 ℃ and 90 ℃ , im prov es thefuel oil consum pti on, the pow e r output from the w hole and di scharge s.2.6 C on t r o l l a b l e c oolin g s y s t e mControll able e ngi ne cooli ng sy ste m tradition e ngi ne cool ing sy ste m bel ongs to the passive form, thestructure sim ple or the cost i s l ow. T he control lable cooling system m ay m ake up at pre sent cool ing sy ste m the insuffi cie ncy . Now the cooli ng sy stem de si gn standard sol ves time the full l oad radi ati on proble m, thus parti al l y shoulde rs time the oversized radi ati on ability wi l l cause the engi ne powe r w aste. This to the li ghtvehi cle said espe ci all y obvi ous, the se ve hi cles m aj ority ti me all unde r the parti al loads go in the urban distri ct, only uses the parti al e ngine power, causes a cooling system hi ghe r l oss. In order to solve the e ngi ne to getdow n the hot questi on in the pe culi ar ci rcumstance, the pre sent cooling sy stem v ol ume w as bi gge r, causes the evaporati on e ffi cie ncy to re duce, has i ncreased the cooling sy stem pow er de m and, leng thene d the engi ne duri ng w arm m achi ne -hour. The controll able engi ne cooli ng sy ste m gene rall y incl udes the se nsor, the executi on and the ele ctri call y controlle d m odule. T he controll able cooling sy stem can act accordi ng to the engi ne w orki ng condition adjustme nt cool ing quantity , reduces the e ngine power loss. In the controll able cooli ng sy ste m, the e xe cuti on for the cooli ng w ate r pump and the therm ostat, ge neral l y and the control val ve is com posed by the ele ctri call y ope rate d w ate r pum p, m ay act accordi ng to requests to adjust the cooli ng quanti ty. Tempe rature sensor for a sy ste m part, but rapidl y beque aths the e ngi ne hot condi tion the controlle r.Controll able i nstall me nt, i f the ele ctri call y ope rated w ate r pump, m ay suppose the tem perature the fi xed point from 90 ℃ to enhance to 11 0 ℃ , save s 2% -5 % fuel oil, C O re duce s 20 % , HC re duce s 10% . W he n ste ady state, the metal te mpe rature rati o tradition cooling sy ste m is hi gh 10 ℃ , the controll able cool ing sy ste m has the qui cker re sponse ability , m ay cool the te mpe rature to m ai ntai n is supposing the fi xed point ±2℃the scope . From 110 ℃ drops to 10 0 ℃ onl y nee ds 2 s. T he engi ne during w arm m achi ne-hour re duces 200 s, the cool ing syste m ope rati ng re g i on draws cl ose to the work li mit re gi on, can reduce the engi ne cooling te m perature and the metal te mpe rature undul ati on scope, re duce s ci rcul ate s the fati gue of metal whi ch the hot l oad creates, lengthens the com ponent l i fe.3C o n c lu s ionIn front of 3 concl usi ons i ntroduce d se ve ra l k ind of advance d cooli ng sy ste ms have the im proveme nt cooli ng sy ste m perform ance the potenti al, can e nhance the fuel oil e ffi ciency and di scharge the pe rform ance. The cooli ng sy stem can control the nature is i m prove s the cooli ng sy ste m the key , can the control ling expression to the engi ne structure prote cti on esse nti al paramete r, like the metal tem pe rature , the re fri ge rant tempe rature and the machi ne oil te mpe rature and so on can control, guarantees the e ngi ne to w ork i n the safety m argi n scope . The cooling sy stem can m ake the rapi d reaction to the diffe rent operating mode, the most e arth saves the fuel, re duces di scharge s, but does not affect the engi ne ove rall perform ance . Looked from the desi gn and the ope rati onal pe rform ance angle that, dive rgence ty pe cooli ng and pre ci se cooli ng uni fies has the ve rygood prospe cts for devel opme nt, both can provi de the ide al engine prote ction, and can enhance the fuel oileffi ciency and discharge the nature. This ki nd of structure is adv antageous to formi ng the engi ne i deal tempe rature di stri bution. Dire ctl y to a cyli nder cover or cap row of ty re v al ve around the suppl ies refri ge rant, reduced the cy li nde r he ad tem pe rature change, causes the cyli nder cover tem pe ra ture di stri bution to be eve ne r, also can m aintai ns the m achine oil and the cy linde r body tem perature at the desi gn ope rating re gion, has a lowerfri cti on to dam age the poll ution wi thdraw a l■.cooli ng sy ste m functi on and m aintenance m ai ntenance method as follow s:1st, the cooling sy stem function, i s part of quantity of he ats w hi ch absorbs the engi ne part carrie s off, guarantee d the diesel e ngine various components m a intai n i n the norm al te mpe rature range.2nd, the cool ing w ate r shoul d be does not contai n dissol ves the X ie salt the soft w ater, l ike cle an rive r w ate r, rain w ater and so on. Do not use hard w ate r and so on the well w ater, w ater see page or sea w ater, guards against produces, causes the e ngi ne to radi ate not good, que stion occurrence and so on ai r cy linde r he at.3rd, w ith the funnel w hen joins the cooli ng w a ter the w a ter tank, m ust preve nt the w ate r spl ashes to on the engi ne and the radi ator, preve nte d on the radi ator fi n and the organism accum ul ates the dust, smears, affe cts the cooli ng effe c t.4th, i f w hen the e ngine l acks the w ater cause s the hy perpy re xi a, cannot i m medi atel y add w ate r, shoul d cause the engi ne i dling spee d to revolve 1 0 □15 mi nute s, afte r the uni form te mpe rature sli ghtl y reduces, sl owl y does not joi n the cooli ng w ate r i n the engi ne situati on.5th, the wi nter, the w ate r tank pl anted agent adds the hot w ate r. A fte r the start should surpass 40de gree-hour the s low re vol uti on to the w ater tem pe rature to be able to w ork. A fte r the w ork had ended, must put the completel y cooling w ate r.6th, must re gul arl y el imi nate i n the w ate r tank , must fre que ntl y scour the sludge to the forced-ai r cool ing engi ne radi ator fin, dirty i s fi l thy . The radi ator fi n cannot dam age, afte r i f dam ages m ust prom ptl y re pl ace, i n orde r to av oi d i nfl uence radi ati on effe ct.4L a t h e sL athe s are m achi ne tool s desi gned pri m aril y to do turni ng, faci ng and bori ng, Very li ttl e turni ng is done on othe r ty pe s of m achine tools, and none can do it w ith equal facility. B e cause l athe s also can do dri lling and re ami ng, their ve rsatil ity pe rmi ts se ve ral ope rations to be done w ith a single setup of the work pie ce . Conseque ntl y, more l athes of various ty pesare used in m anufacturing than any othe r m achine tool.The esse nti al compone nts of a l a the are the bed, he adstock asse m bl y, tail stock assem bl y, and the le ads cre w and fee d rod.The be d is the backbone of a l athe. It usuall y is m ade of we ll norm al ized or age d gray or nodul ar cast iron and provide s s he av y, ri gi d frame on w hi ch al l the othe r basi c com ponents are m ounted. Two sets of parallel, longitudi nal w ays, i nner and outer, are containe d on the be d, usuall y on the uppe r side. S ome make rs use an inve rte d V-shape for all four w ay s, whe re as others utilize one i nve rte d V and one fl at w ay i n one or both sets, The y are preci si on-machi ned to assure accuracy of al i gnme nt. On m ost m odern l athes the w ay are surface -hardene d to re sist w e ar and abrasi on, but pre cauti on should be taken i n ope rati ng a la the to assure that the w ay s are not dam age d. A ny i naccuracy in the m usuall y means that the accuracy of the enti re l athe is destroy ed.The he adstock is m ounte d in a foxe d position on the inne r w ay s , usuall y at the left end of the bed. It provides a pow e red means of rotating the word at vari ous speeds . Essenti all y, it consists of a hol low spi ndle, mounted i n accurate be ari ngs, and a set of transmission ge ars-si mil ar to a truck transmission—through w hi ch the spi ndle can be rotated at a num ber of speeds. M ost l athes provi de from 8 to 18 speeds, usuall y i n a geometri c ratio, and on m ode rn l athes a ll the spee ds can be obtaine d me rel y by movi ng from two to four le vers. A n i ncre asing trend i s to provide a continuousl y v ari able speed range through e lectri cal or mechani cal dri ves.B ecause the accuracy of a l athe is gre atl y depe nde nt on the spi ndle, it i s of he av y construction and mounted in he avybe ari ngs, usuall y prel oade d tape red rolle r or bal l ty pes. T he spi ndle has a hole exte nding through its length, through w hi ch l ong bar stock can be fed. T he size of m axi mum size of bar stock that can be m achi ned whe n the m aterial must be fe d through spi ndle .The tail sti cd asse mbl y consi sts , esse nti all y, of three parts.A lowe r casti ng fi ts on the i nne r w ay s of the bed and can slide longitudi nall y the reon, w ith a me ans for cl am ping the e nti re assem bl y in any desi re d l ocation, An upper casti ng fits on the lowe r one and can be moved transversel y upon it, on some type of ke y e d w ay s, to permit ali gni ng the assem bl y is the tail stock quill. Thi s i s a holl ow steel cy li nder, usuall y about 51 to 76 m m( 2to 3 inches) i n diamete r, that can be m ove d seve ral i nches longitudi nall y i n and out of the upper casti ng by me ans of a hand w heel and scre w.The size of a l athe is desi gnate d by tw o dime nsi ons. The fi rst is k now n as the swing. This is the m axi m um di amete r of work that can be rotated on a l athe . It is approxim atel y tw i ce the distance betw ee n the li ne conne cting the la the ce nte rs and the ne are st poi nt on the w ay s, The se cond size dim ensi on is the m axi mum distance betw een cente rs . The sw i ng thus i ndi cate s the m axim um w ork pie ce di amete r that can be turne d i n the lathe, w hile the distance betw een centers i ndicates the m axi mum length of w ork pie ce that can be mounte d betw een ce nte rs.Engi ne l athe s are the ty pe most freque ntl y use d in m anufacturi ng. The y are he av y -duty m achine tools with all the com ponents descri bed pre viousl y and have powe r drive for al l tool move ments exce pt on the compound rest. T he y com monl y range i n size from 305 to 610 mm( 12 to 2 4 inches) sw ing and from 610 to 12 19 m m( 2 4 to 48 i nches) ce nte r distances, but sw ings up to 1270 m m( 50 inches) and ce nte r distances up to 3658 m m( 12 feet) are not uncom mon. M ost have chi p pans and a built-i n cool ant ci rcul ating syste m. S m alle r engine lathes-with swi ngs usuall y not over 330 m m ( 1 3 inches ) –a l so are avail able in bench ty pe, de si gned for the bed to be mounted on a bench on a be nch or cabine t.Although engine l athes are ve rsatile and ve ry use ful, be cause of the ti me re qui re d for changi ng andsetting tool s and for m aki ng me asure me nts on the w ork piece , thy are not suitable for quantity producti on. Often the actual chip-producti on ti ne is less than 30 % of the total cy cle time . In additi on, a skil led machi nist is requi red for all the ope rati ons, and such pe rsons are costl y and ofte n i n short suppl y. How eve r, much of the ope rator ’s ti me is consumed by sim ple, re petitious adj ustments and in w atchi ng chips bei ng m ade. Conseque ntl y, to reduce or eli mi nate the am ount of skille d l abor that is re quire d, turret lathes, scre w m achi nes, and other ty pes of sem iautom atic and autom ati c l athes have been hi ghl y devel oped and are w i del y use d i n m anufacturing.5L im its and Toler ancesM achine parts are m anufacture d so the y are inte rchange able. In othe r words, e ach part of a m achi ne or me chanism is m ade to a certai n size and shape so w il l fit i nto any othe r m achine or me chanism of the same type. To m ake the part inte rchange able , e ach i ndi vi dual part m ust be m ade to a size that w i ll fit the m ati ng part in the corre ct w ay . It is not onl y i m possible, but also im practi cal to m ake m any parts to an ex act size. Thi s is because machi nes are not pe rfe ct, and the tool s be come w orn. A sl i ght vari ation from the e x act size i s al way s all owed. T he amount of this v ari ation depe nds on the ki nd of part being m anufacture d. For ex am ples part mi ght be m ade 6 in. long w i th a vari ati on all owed of 0. 003 ( three-thousandths) in. above and bel ow this size . There fore, the part coul d be 5 .997 to 6. 003 in. and s till be the corre ct size . The se are k now n as the l imi ts. T he diffe rence betw ee n upper and l ow er li mits is calle d the tolerance.1 概述随着发动机采用更加紧凑的设计和具有更大的比功率，发动机产生的废热密度也随之明显增大。

怎样介绍温度英语作文Title: Explaining Temperature in English。

Temperature is a fundamental concept in physics and meteorology, describing the degree of hotness or coldness of an object or environment. It plays a crucial role in our daily lives, influencing everything from the weather to the functioning of machines. In this essay, we will delve into the intricacies of temperature, exploring its definition, measurement, and significance.Definition of Temperature:Temperature is defined as the average kinetic energy of the particles in a substance or system. In simpler terms, it indicates how fast the particles are moving within an object or a region. When particles move faster, the temperature is higher, resulting in a sensation of warmth, whereas slower particle movement corresponds to lower temperatures and a sensation of coldness.Measurement of Temperature:Temperature is typically measured using various scales, with the most commonly used ones being Celsius (°C), Fahrenheit (°F), and Kelvin (K). 。

温度计的相关作文英语The thermometer is an important tool used to measure temperature. It is widely used in various fields, such as weather forecasting, medical treatment, and scientific research. In this essay, I will discuss the history, types, and applications of thermometers.The history of the thermometer can be traced back to ancient times. The first thermometer was invented by Galileo Galilei in the early 17th century. He used a glass tube filled with water and air to measure temperature changes. Later, in 1714, Gabriel Fahrenheit invented the mercury thermometer, which is still widely used today.There are several types of thermometers, including liquid-in-glass, bimetallic, and electronic thermometers. Liquid-in-glass thermometers use a liquid, such as mercury or alcohol, to measure temperature. Bimetallic thermometers use two different metals that expand at different rates to measure temperature. Electronic thermometers use electronicsensors to measure temperature.Thermometers have many applications in various fields. In weather forecasting, thermometers are used to measure the temperature of the air. This information is used to predict weather patterns and make weather forecasts. In medical treatment, thermometers are used to measure body temperature. This information is used to diagnose and treat illnesses. In scientific research, thermometers are used to measure the temperature of different substances. This information is used to study the properties and behavior of different materials.In conclusion, the thermometer is an important tool used to measure temperature. It has a rich history and many different types. Thermometers have many applications in various fields, including weather forecasting, medical treatment, and scientific research. As technology continues to advance, new and more advanced thermometers will be developed, further expanding the range of applications for this important tool.。

Design of the Temperature Control System Based on AT89C51ABSTRACTThe principle and functions of the temperature control system based on micro controller AT89C51 are studied, and the temperature measurement unit consists of the 1-Wire bus digital temperature sensor DS18B20. The system can be expected to detect the preset temperature, display time and save monitoring data. An alarm will be given by system if the temperature exceeds the upper and lower limit value of the temperature which can be set discretionarily and then automatic control is achieved, thus the temperature is achieved monitoring intelligently within a certain range. Basing on principle of the system, it is easy to make a variety of other non-linear control systems so long as the software design is reasonably changed. The system has been proved to be accurate, reliable and satisfied through field practice.KEYWORDS: AT89C51; micro controller; DS18B20; temperature1 INTRODUCTIONTemperature is a very important parameter in human life. In the modern society, temperature control (TC) is not only used in industrial production, but also widely used in other fields. With the improvement of the life quality, we can find the TC appliance in hotels, factories and home as well. And the trend that TC will better serve the whole society, so it is of great significance to measure and control the temperature. Based on the AT89C51 and temperature sensor DS18B20, this system controls the condition temperature intelligently. The temperature can be set discretionarily within a certain range. The system can show the time on LCD, and save monitoring data; and automatically control the temperature when the conditiontemperature exceeds the upper and lower limit value. By doing so it is to keep the temperature unchanged. The system is of high anti-jamming, high control precision and flexible design; it also fits the rugged environment. It is mainly used in people's life to improve the quality of the work and life. It is also versatile, so that it can be convenient to extend the use of the system. So the design is of profound importance. The general design, hardware design and software design of the system are covered.1.1 IntroductionThe 8-bit AT89C51 CHMOS microcontrollers are designed to handle high-speed calculations and fast input/output operations. MCS 51 microcontrollers are typically used for high-speed event control systems. Commercial applications include modems, motor-control systems, printers, photocopiers, air conditioner control systems, disk drives, and medical instruments. The automotive industry use MCS 51 microcontrollers in engine-control systems, airbags, suspension systems, and antilock braking systems (ABS). The AT89C51 is especially well suited to applications that benefit from its processing speed and enhanced on-chip peripheral functions set, such as automotive power-train control, vehicle dynamic suspension, antilock braking, and stability control applications. Because of these critical applications, the market requires a reliable cost-effective controller with a low interrupt latency response, ability to service the high number of time and event driven integrated peripherals needed in real time applications, and a CPU with above average processing power in a single package. The financial and legal risk of having devices that operate unpredictably is very high. Once in the market, particularly in mission critical applications such as an autopilot or anti-lock braking system, mistakes are financially prohibitive. Redesign costs can run as high as a $500K, much more if the fix means 2 back annotating it across a product family that share the same core and/or peripheral design flaw. In addition, field replacements ofcomponents is extremely expensive, as the devices are typically sealed in modules with a total value several times that of the component. To mitigate these problems, it is essential that comprehensive testing of the controllers be carried out at both the component level and system level under worst case environmental and voltage conditions. This complete and thorough validation necessitates not only a well-defined process but also a proper environment and tools to facilitate and execute the mission successfully. Intel Chandler Platform Engineering group provides post silicon system validation (SV) of various micro-controllers and processors. The system validation process can be broken into three major parts. The type of the device and its application requirements determine which types of testing are performed on the device.1.2 The AT89C51 provides the following standard features4Kbytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bittimer/counters, a five vector two-level interrupt architecture, a full duple ser-ial port, on-chip oscillator and clock circuitry. In addition, the AT89C51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and interrupt sys -tem to continue functioning. The Power-down Mode saves the RAM contents but freezes the oscil–lator disabling all other chip functions until the next hardware reset.1.3Pin DescriptionVCC Supply voltage.GND Ground.Port 0：Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, thepins can be used as high impedance inputs. Port 0 may also be configured to be the multiplexed low order address/data bus during accesses to external program and data memory. In this mode P0 has internal pull ups. Port 0 also receives the code bytes during Flash programming, and outputs the code bytes during program verification. External pull ups are required during program verification.Port 1：Port 1 is an 8-bit bi-directional I/O port with internal pull ups. The Port 1 output buffers can sink/so -urce four TTL inputs. When 1s are written to Port 1 pins they are pulled high by the internal pull ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pullups. Port 1 also receives the low-order address bytes during Flash programming and verification.Port 2：Port 2 is an 8-bit bi-directional I/O port with internal pull ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins they are pulled high by the internal pull ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull ups. Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses (MOVX@DPTR). In this application, it uses strong internal pull-ups when emitting 1s. During accesses to external data memory that use 8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-order address bits and some control signals durin Flash programming and verification.Port 3：Port 3 is an 8-bit bi-directional I/O port with internal pull ups. The Port 3 output buffers can sink/sou -rce four TTL inputs. When 1s are written toPort 3 pins they are pulled high by the internal pull ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull ups.Port 3 also serves the functions of various special features of the AT89C51 as listed below:RST：Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device.ALE/PROG：Address Latch Enable output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped duri-ng each access to external Data Memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.PSEN：Program Store Enable is the read strobe to external program memory. When theAT89C51 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.EA/VPP：External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset. EA should be strapped to VCC for internal program executions. This pin alsreceives the 12-volt programming enable voltage (VPP) during Flash programming, for parts that require 12-volt VPP.XTAL1：Input to the inverting oscillator amplifier and input to the internal clock operating circuit.XTAL2 ：Output from the inverting oscillator amplifier. Oscillator CharacteristicsXTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier which can be configured for use as an on-chip oscillator, as shown in Figure 1. Either a quartz crystal or ceramic resonator may be used. To drive the device from an external clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in Figure 2.There are no requirements on the duty cycle of the external clock signal, since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed. Idle Mode In idle mode, the CPU puts itself to sleep while all the on chip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registers remain unchanged during this mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset. It should be noted that when idle is terminated by a hard ware reset, the device normally resumes program execution, from where it left off, up to two machine cycles before the internal reset algorithm takes control. On-chip hardware inhibits access to internal RAM in this event, but access to the port pins is not inhibited. To eliminate the possibility of an unexpected write to a port pin when Idle is terminated by reset, the instruction following the one that invokes Idle should not be one that writes to a port pin or to external memory.Power-down ModeIn the power-down mode, the oscillator is stopped, and the instruction that invokes power-down is the last instruction executed. The on-chip RAM and Special Function Registers retain their values until the power-down mode is terminated. The only exit from power-down is a hardware reset. Reset redefines the SFRS butdoes not change the on-chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize. The AT89C51 code memory array is programmed byte-by byte in either programming mode. To program any nonblank byte in the on-chip Flash Memory, the entire memory must be erased using the Chip Erase Mode.2 Programming AlgorithmBefore programming the AT89C51, the address, data and control signals should be set up according to the Flash programming mode table and Figure 3 and Figure 4. To program the AT89C51, take the following steps.1. Input the desired memory location on the address lines.2. Input the appropriate data byte on the data lines.3. Activate the correct combination of control signals.4. Raise EA/VPP to 12V for the high-voltage programming mode.5. Pulse ALE/PROG once to program a byte in the Flash array or the lock bits. The byte-write cycle is self-timed and typically takes no more than 1.5 ms. Repeat steps 1 through 5, changing the address and data for the entire array or until the end of the object file is reached. Data Polling: The AT89C51 features Data Polling to indicate the end of a write cycle. During a write cycle, an attempted read of the last byte written will result in the complement of the written datum on PO.7. Once the write cycle has been completed, true data are valid on all outputs, and the next cycle may begin. Data Polling may begin any time after a write cycle has been initiated.2.1Ready/Busy:The progress of byte programming can also be monitored by the RDY/BSY output signal. P3.4 is pulled low after ALE goes high during programming to indicate BUSY. P3.4 is pulled high again when programming is done to indicate READY.Program Verify:If lock bits LB1 and LB2 have not been programmed, the programmed code data can be read back via the address and data lines for verification. The lock bits cannot be verified directly. Verification of the lock bits is achieved by observing that their features are enabled.2.2 Chip Erase:The entire Flash array is erased electrically by using the proper combination of control signals and by holding ALE/PROG low for 10 ms. The code array is written with all “1”s. The chip erase operation must be executed before the code memory can be re-programmed.2.3 Reading the Signature Bytes:The signature bytes are read by the same procedure as a normal verification of locations 030H, 031H, and 032H, except that P3.6 and P3.7 must be pulled to a logic low. The values returned areas follows.(030H) = 1EH indicates manufactured by Atmel(031H) = 51H indicates 89C51(032H) = FFH indicates 12V programming(032H) = 05H indicates 5V programming2.4 Programming InterfaceEvery code byte in the Flash array can be written and the entire array can be erased by using the appropriate combination of control signals. The write operation cycle is self timed and once initiated, will automatically time itself to completion.A microcomputer interface converts information between two forms. Outside themicrocomputer the information handled by an electronic system exists as a physical signal, but within the program, it is represented numerically. The function of any interface can be broken down into a number of operations which modify the data in some way, so that the process of conversion between the external and internal forms is carried out in a number of steps. An analog-to-digital converter(ADC) is used to convert a continuously variable signal to a corresponding digital form which can take any one of a fixed number of possible binary values. If the output of the transducer does not vary continuously, no ADC is necessary. In this case the signal conditioning section must convert the incoming signal to a form which can be connected directly to the next part of the interface, the input/output section of the microcomputer itself. Output interfaces take a similar form, the obvious difference being that here the flow of information is in the opposite direction; it is passed from the program to the outside world. In this case the program may call an output subroutine which supervises the operation of the interface and performs the scaling numbers which may be needed for digital-to-analog converter(DAC). This subroutine passes information in turn to an output device which produces a corresponding electrical signal, which could be converted into analog form using a DAC. Finally the signal is conditioned(usually amplified) to a form suitable for operating an actuator. The signals used within microcomputer circuits are almost always too small to be connected directly to the outside world”and some kind of interface must be used to translate them to a more appropriate form. The design of section of interface circuits is one of the most important tasks facing the engineer wishing to apply microcomputers. We have seen that in microcomputers information is represented as discrete patterns of bits; this digital form is most useful when the microcomputer is to be connected to equipment which can only be switched on or off, where each bit might represent the state of a switch or actuator. To solve real-world problems, a microcontroller must have more than just a CPU, a program, and a data memory. In addition, it must contain hardware allowing the CPU to access information from the outside world. Once theCPU gathers information and processes the data, it must also be able to effect change on some portion of the outside world. These hardware devices, called peripherals, are the CPU’s window to the outside.The most basic form of peripheral available on microcontrollers is the general purpose I70 port. Each of the I/O pins can be used as either an input or an output. The function of each pin is determined by setting or clearing corresponding bits in a corresponding data direction register during the initialization stage of a program. Each output pin may be driven to either a logic one or a logic zero by using CPU instructions to pin may be viewed (or read.) by the CPU using program instructions. Some type of serial unit is included on microcontrollers to allow the CPU to communicate bit-serially with external devices. Using a bit serial format instead of bit-parallel format requires fewer I/O pins to perform the communication function, which makes it less expensive, but slower. Serial transmissions are performed either synchronously or asynchronously.3 SYSTEM GENERAL DESIGNThe hardware block diagram of the TC is shown in Fig. 1. The system hardware includes the micro controller, temperature detection circuit, keyboard control circuit, clock circuit, Display, alarm, drive circuit and external RAM. Based on the AT89C51, the DS18B20 will transfer the temperature signal detected to digital signal. And the signal is sent to the micro controller for processing. At last the temperature value is showed on the LCD 12232F. These steps are used to achieve the temperature detection. Using the keyboard interface chip HD7279 to set the temperature value, using the micro controller to keep a certain temperature, and using the LCD to show the preset value for controlling the temperature. In addition, the clock chip DS1302 is used to show time and the external RAM 6264 is used to save the monitoring data. An alarm will be given by buzzer in time if the temperature exceeds the upper and lower limit value of the temperature.3.1 HARDWARE DESIGNA. Micro controllerThe AT89C51 is a low-power, high-performance CMOS 8-bit micro controller with 4K bytes of in-system programmable Flash memory. The device is manufactured using At mel’s high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the At mel AT89C51 is a powerful micro controller which provides a highly-flexible and cost-effective solution to many embedded control applications. Minimum system of the micro controller is shown in Fig. 2. In order to save monitoring data, the 6264 is used as an external RAM. It is a static RAM chip, low-power with 8K bytes memory.B. Temperature Detection CircuitThe temperature sensor is the key part in the system. The Dallas DS18B20 is used, which supports the 1-Wire bus interface, and the ON-BOARD Patented is used internally. All the sensor parts and the converting circuit are integrated in integrated circuit like a transistor [1]. Its measure range is -55℃~125 ℃, and the precision between -10℃~85℃is ±0.5℃[2 ,3]. The temperature collected by the DS18B20 is transmitted in the 1-Wire bus way, and this highly raises the system anti-jamming and makes it fit in situ temperature measurement of the rugged environment [4]. There are two power supply ways for the DS18B20. The first is external power supply: the first pin of the DS18B20 is connected to the ground; the second pin serves as signal wire and the third is connected to the power. The second way is parasite power supply [5]. As the parasite power supply will lead to the complexity of the hardware circuit, the difficulty of the software controland the performance degradation of the chip, etc. But the DS18B20(s) can be connected to the I/O port of the micro controller in the external power supply way and it is more popular. Therefore the external power supply is used and the second pin is connected to the pin P1.3 of the AT89S51. Actually, if there are multipoint to be detected, the DS18B20(s) can be connected to the 1-Wire bus. But when the number is over 8, there is a concern to the driving and the more complex software design as well as the length of the 1-Wire bus. Normally it is no more than 50m. To achieve distant control, the system can be designed in to a wireless one to breakthe length limit of the 1-Wire bus [6].C. LCD CircuitThe LCD 12232F is used, which can be used to show characters, temperature value and time, and supply a friendly display interface. The 12232F is a LCD with 8192 128×32 pixels Chinese character database and 128 16×8 pixels A SCII character set graphics. It mainly consists of row drive/column drive and 128×32 full lattice LCD with the function of displaying graphics as well as 7.5×2 Chinese characters. It is in a parallel or serial mode to connect to external CPU [7]. In order to economize the hardware resource, the 12232F should be connected to the AT89S51 in serial mode with only 4 output ports used. The LCD grayscale can be changed by adjusting the variable resistor connected the pin Vlcd of the LCD. CLK is used to transmit serial communication clock. SID is used to transmit serial data. CS is used to enable control the LCD. L+ is used to control the LCD backlight power.D. Clock CircuitThe Dallas DS18B20 is used, which is a high performance, low-power and real-time clock chip with RAM. The DS18B20 serves in the system with calendar clock and is used to monitor the time. The time data is read and processed by the AT89C51 and then displayed by the LCD. Also the time can be adjusted by the keyboard. TheDS18B20 crystal oscillator is set at 32768Hz, and the recommended compensation capacitance is 6pF. The oscillator frequency is lower, so it might be possible not to connect the capacitor, and this would not make a big difference to the time precision. The backup power supply can be connected to a 3.6V rechargeable battery.E. Keyboard Control CircuitThe keyboard interface in the system is driven by the HD7279A which has a +5V single power supply and which is connected to the keyboard and display without using any active-device. According to the basic requirements and functions of the system, only 6 buttons are needed. The system's functions are set by the AT89C51 receiving the entered data. In order to save the external resistor, the 1×6 keyboard is used, and the keyboard codes are defined as: 07H, 0FH, 17H, 1FH, 27H, 2FH. The order can be read out by reading the code instruction. HD7279A is connected to the AT89S51 in serial mode and only 4 ports are need. As shown in Fig. 6, DIG0~DIG5 and DP are respectively the column lines and row line ports of the six keys which achieve keyboard monitoring, decoding and key codes identification.F. Alarm CircuitIn order to simplify the circuit and convenient debugging, a 5V automatic buzzer is used in the alarm circuit [8]. And this make the software programming simplified. As shown in Fig. 7, it is controlled by the PNP transistor 9012 whose base is connected to the pin P2.5 of the AT89C51. When the temperature exceeds the upper and lower limit value, the P2.5 output low level which makes the transistor be on and then an alarm is given by the buzzer.G. Drive CircuitA step motor is used as the drive device to control the temperature. The four-phase and eight-beat pulse distribution mode is used to drive motor and thesimple delay program is used to handle the time interval between the pulses to obtain different rotational speed. There are two output states for the step motor. One: when the temperature is over the upper value, the motor rotates reversely (to low the temperature), while when lower than the lower limit value, the motor rotates normally (to raise the temperature); besides not equals the preset value. Two: when the temperature is at somewhere between the two ends and equals the preset value, the motor stops. These steps are used to achieve the temperature control. In addition, the motor speed can also be adjusted by relative buttons. As shown in Fig. 8, the code data is input through ports A11~A8 (be P2.3~P2.0) of the AT89C51 and inverted output by the inverter 74LS04. Finally it is amplified by the power amplifier 2803A to power the motor.3.2 SOFTWARE DESIGNAccording to the general design requirement and hardware circuit principle of the system, as well as the improvement of the program readability, transferability and the convenient debugging, the software design is modularized. The system flow mainly includes the following 8 steps: POST (Power-on self-test), system initiation, temperature detection, alarm handling, temperature control, clock chip DS18B20 operation, LCD and keyboard operation. The main program flow is shown in Fig. 9. Give a little analysis to the above 8 tasks, it is easy to find out that the last five tasks require the real time operation. But to the temperature detection it can be achieved with timer0 timing 1 second, that is to say temperature detection occurs per second. The system initiation includes global variable definition, RAM initiation, special function register initiation and peripheral equipment initiation. Global variable definition mainly finishes the interface definition of external interface chip connected to the AT89C51, and special definition of some memory units. RAM initiation mainly refers to RAM processing. For example when the system is electrified the time code will be stored in theinternal unit address or the scintillation flag will be cleared. The special function register initiation includes loading the initial value of timer and opening the interrupt. For example, when the system is electrified the timer is initialized. The peripheral equipment initiation refers to set the initial value of peripheral equipment. For example, when the system is electrified, the LCD should be initialized, the start-up display should be called, the temperature conversion command should be issued firstly and the clock chip DS18B20 should also be initialized. The alarm handling is mainly the lowering and the raising of temperature to make the temperature remain with the preset range. When the temperature is between the upper and the lower limit value, it goes to temperature control handling, that is to say the temperature need to be raised or lowered according to the preset value. By doing so make the condition temperature equal to the preset value and hence to reach the temperature target.4 CONCLUSIONThe temperature control system has the advantages of friendly human-computer interaction interface, simple hardware, low cost, high temperature control precision (error in the range of ±1 ℃), convenience and versatility, etc. It c an be widely used in the occasions with -55℃to 125℃range, and there is a certain practical value.温度控制系统的设计摘要研究了基于AT89C51单片机温度控制系统的原理和功能，温度测量单元由单总线数字温度传感器DS18B20构成。

介绍体温计的英语小短文An English passage introducing the thermometer Because of the epidemic, recently "taking the temperature" has become an indispensable part of our life, in and out of the village, into the unit, into the supermarket, into the railway station, into the subway station... all on the forehead "di" so, take the temperature at home has become one of the daily activities, so about measuring the temperature tool —— thermometer, do you have enough understanding? Now let me introduce two types of common thermometers!Glass-mercury thermometer①principle:The working substance of the glass thermometer is mercury, its glass bubble volume is much larger than that of the thin tube above; during the temperature measurement, as the temperature increases, the mercury in the bubble expands to the straight tube through the neck part to the tube, when the body temperature, the cold volume contraction, in the narrow curved neck is disconnected, make the mercury in the tube, still maintain the height of the mercury column and human body contact, so it still represents the temperature of the human body.② measuring point:We generally measure body temperature in three parts, that is the mouth, armpit and anus.③usage method:The more common method is the armpit measurement, we first swing the mercury thermometer meter degree below 35②, and then the thermometer mercury end on the top of the armpit after the clamp. Make sure the thermometer is in close contact with the skin and remove it after about 5 minutes. Read the degree and wipe it clean with drawing paper to use it next time.The armpit is more easy to sweat, when the measurement must wipe the sweat under the armpit first.axillary temperature should be noted that the time should be controlled between 5 and 6 minutes.When measuring the mouth, first swing the mercury thermometer meter degree below 35②, put the thermometer under the tongue with a little force to pressure. Be sure to disinfect the surface of the thermometer before leaving the mouth. Time is 3 minutes, remember not to speak in the middle.When measuring the mouth, be careful not to bite the thermometer too hard. If it is broken, there will be a risk of poisoning. Consciousness patients and small children are best not to use this measurement.After the oral temperature measurement, still wipe it with drawing paper, then wipe the whole mercury thermometer with an alcohol cotton ball and put it back in place for the next time.The method of anal measurement is generally used for coma patientor children, the patient supine position, anal table head with oil lubrication, after insert anus slowly, deep reach anal surface 1 / 2 so far, placed after 3 minutes reading.Read the mercury thermometer equal to the upper surface of the liquid column in the mercury thermometer. Hold the tail of the mercury thermometer in one hand, namely away from the end of the mercury column, so that the eyes keep at the same level as the thermometer, and then slowly turn the thermometer, from the front to see the very thick silver column (the middle silver line) can see the line is in the middle of the count, then you can read the temperature number.② Advantages and Disadvantages:Advantages: cheap price, small size, easy to operate. Because the structure of glass is relatively dense, the performance of mercury is very stable, so it has the characteristics of accurate display value and high stability.Disadvantages: mercury is toxic. The mercury thermometer is made of glass, which is easily broken. The mercury inside, or mercury leaks, whether accidentally taken, inhaled or touching a certain amount, can cause brain and liver damage and other body damage, and the broken glass will also hurt people.Therefore, China will completely ban the production of mercury-containing thermometers and mercury-containing sphygmomanometer products starting from January 1,2026.② crushing treatment:Mercury break should first take a gloves, gloves with good after pick up the debris into the bag, collect scattered mercury, do not use a broom to sweep, or use a mop to drag, because this may make mercury into some scattered mercury, if there is tape in the home, you can use tape to stick.After the thermometer breaks, the small mercury beads may splash far away, so be sure to carefully check if there is some small mercury inside the house. If there is sulfur powder in the home, sprinkle a little sulfur powder on the mercury.After the broken thermometer is processed, the garbage should be carefully stored in the children inside the home, the elderly can not touch the place, and also ask the family not to touch. If the child in the home is more naughty, may go to see, this time must tell the child this substance is toxic substances, once touched on the hand will have very serious consequences, warn children not to casually touch.。