外文文献及翻译_Introductions to temperature control and PID controllers
扩展温度英语作文
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
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.。
外文文献中文版
热腐蚀是镧系元素镁六铝酸盐热障涂层材料的主要失效机制之一，是由于熔融盐的反应。研究在650至950 ℃的不同温度下，该NdMgAl11O19陶瓷使用V2O5进行热化学反应，使用X射线衍射仪、扫描电子显微镜和能量色散X射线光谱范围。NdMgAl11O19陶瓷与V2O5反应的腐蚀产物主要取决于腐蚀温度。在650 ℃时，腐蚀产物主要有AlVO4和NdVO4。然而，在750 ℃熔融的V2O5与NdMgAl11O19反应形成NdVO4、MgV2O6、少量AlVO4和氧化铝 。在850 ℃时，腐蚀产物由θ -Al2O3和NdVO4和少量MgAl2O4。经过在950 ℃时的热腐蚀，腐蚀产物由α - Al2O3和NdVO4和MgAl2O4。
图4示出的NdMgAl11O19陶瓷暴露于V2O5，在750 ℃，在空气中10小时的X射线衍射图案。图4的衍射图案是与来自在650℃下获得的不同。除此之外NdVO4，少量AlVO4和未反应的NdMgAl11O19阶段，一个新的阶段，MgV2O6（JCPDS文件编号34-0013 ） ，是根据X射线衍射分析发现。此外，腐蚀温度从650到750 ℃的增加，AlVO4相强度明显减小。图5a显示的NdMgAl11O19陶瓷暴露V2O5在750℃空气中10小时的典型的表面形貌。有四种类型的典型特征，即灰色多面体颗粒，大薄膜状的形式，白色多面体颗粒和小暗粒。由图的EDS结果，5C和D的标示图中不同的位置，图5a，已确定的元素都符合AlVO4和MgV2O6（位置E）和NdVO4（位置F）的反应产物的存在很好地吻合。在图5a中G所示的位置获得的EDS谱图表明，小暗粒可以是氧化铝。根据V2O5-Al2O3的二元相图，AlVO4熔化固液异化，Al2O3和V2O5液体混合物和Al2O3在约695 ℃ [25] 。然而，X射线衍射图案没有标识Al2O3相，这表明，氧化铝的量是低的，它可以是不能够通过X射线衍射来识别的存在。
介绍温度句式英语作文
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
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
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
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.。
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毕业设计(论文)外文资料翻译学院：电子与电气工程学院专业：测控技术与仪器姓名：学号：外文出处：/(用外文写)附件： 1.外文资料翻译译文；2.外文原文。
指导教师评语：所选内容与课题相关，对课题设计参考具有一定价值；翻译具有一定难度，工作量适中；译文基本正确，语句通顺，但也存在部分错误。
总体评价：良签名：2012 年 3 月15 日注：请将该封面与附件装订成册。
附件1：外文资料翻译译文温度控制和PID控制器简介过程控制系统：自动过程控制系统是指把温度、压力、流量、成份等相关的过程变量保持在要求的运行值的一类系统。
过程实际上是动态的。
变化总是时时在发生的，此时如果不采取相应的措施，那些与安全、产品质量和生产率有关的工艺参数就不能满足设计要求。
为了理清思路，让我们来看一下热交换器，流体在这个过程中被过冷凝蒸汽加热，过程如图1所示。
图1热交换器这一装置的目的是将流体由入口温度Ti（t）加热到某一期望的出口温度T(t)。
如前所述，加热介质是冷凝蒸汽。
只要周围没有热损耗，即热交换器和管道间的隔热性都很好，过程流体获得的热量就等于蒸汽释放的热量。
在这个过程中很多变量会发生变化，导致出口温度偏离期望值。
如果出现这种情况，就应该采取一些措施来校正温度偏差，目的是控制出口温度至期望值。
实现该目的的一种方法是首先设定初始温度T(0)，然后与期望值相比较，由比较结果决定如何校正偏差。
蒸汽的流量可用于偏差的校正。
就是说，如果温度高于期望值，就关小蒸汽阀来减小进入热交换器的蒸汽流量；若温度低于期望值，就开大蒸汽阀来增加进入换热器的蒸汽流量。
所有这些操作都可由操作员手动完成，操作很简单，不会出现什么问题。
但是，由于多数过程对象都有很多变量需要保持为某一期望值，这个校正过程就需要许多的操作员来进行。
因此，我们想自动完成这种控制。
就是说，我们需要一种无需操作人员介入就可以控制变量的设备。
这就是所谓的自动过程控制。
为了实现上述目标，就需要设计一个可行的控制系统。
图2为一个可行的控制系统及其基本构件。
图2热交换器的控制回路首先要做的是测量过程流体的出口温度，这一任务由传感器(热电偶、热电阻等)完成。
传感器连接到发射器上，发射器将传感器的输出信号转换为足够大的信号传送给控制器。
控制器接收与温度相关的信号并与期望值进行比较。
根据比较的结果，控制器决定如何保持温度为期望值。
基于这一结果，控制器再发一信号给执行机构来轮流控制蒸汽流量。
以上的叙述表明整个控制系统有四个基本组成部分，分别是：(1)传感器，也称为一次元件。
(2)发射器，也称二次元件。
(3)控制器，控制系统的“大脑”。
(4)执行机构，通常是一个控制阀，但并不全是。
其他常用的执行机构有变速泵、传送装置和电动机。
这些元件的重要性在于它们执行每个控制系统中都必不可少的3个基本操作，即：(1)测量：被控量的测量通常由传感器和发射器共同完成。
(2)决策：根据测量结果，控制器必须决定如何进行操作维持输出为期望值。
(3)操作：根据控器的处理，系统必须执行某种操作，这通常由执行机构来完成。
如上所述，每个控制系统都必须有M，D和A这三种操作。
PID控制器可以是独立控制器（也可以叫做单回路控制器），可编程控制器（PLCS）中的控制器，嵌入式控制器是用VB或C#编写的计算机程序软件。
PID控制器是过程控制器，它具有如下特征：（1）连续过程控制；（2）模拟输入（也被称为“测量量”或“过程变量”或“PV”）；（3）模拟输出（简称为“输出”）；（4）基准点（SP）；（5）比例、积分以及微分常数；“连续过程控制”的例子有温度、压力、流量及液位控制。
例如：控制一个容器的热量。
对于简单的控制，你需要两个具有温度限定功能的传感器（一个温度下限，一个温度上限）。
当低温限定传感器接通时就会打开加热器，当温度升高到高温限定传感器时就会关闭加热器。
这类似于大多数家庭使用的空调及供暖设备的温度自动调节器。
反过来，PID控制器能够接受像实际温度这样的输入，来控制阀门，这个阀门能够控制进入加热器的气体流量。
PID控制器自动地找到加热器中气体的合适流量，这样就保持了温度在基准点稳定。
温度稳定了，就不会在高低两点间上下跳动了。
如果基准点降低，PID控制器就会自动降低加热器中气体的流量。
如果基准点升高，PID控制器就会自动的增加加热器中气体的流量。
同样地，对于高温，晴朗的天气(当外界温度高于加热器时)及阴冷，多云的天气，PID控制器都会自动调节。
模拟输入（测量量）叫做“过程变量”或“PV”。
你希望PV能够达到你所控制过程参数的高精确度。
例如，如果我们想要保持温度为+1度或—1度，我们至少要努力使其精度保持在0.1度。
如果是一个12位的模拟输入，传感器的温度范围是从0度到400度，我们计算的理论精确度就是400除以44096 ，即0．097656度。
我们之所以说这是理论上的因为我们假设温度传感器，电线及模拟转换器上没有噪音和误差。
还有其他的假定，如线性等等。
即使是有大量的噪音和其他问题，按理论精确度的1／10计算，1度精确度的数值应该很容易得到的。
模拟输出经常被简称为“输出”。
经常在0％到100％之间给出。
在这个热量的例子中阀门完全关闭(0％)，完全打开(100％)。
基准点(SP)很简单，即你想要什么样的过程量。
在这个例子中你想要该过程处于怎样的温度。
PID控制器的任务是维持输出在某一个程度上，这样在过程变量(PV)和基准点(SP)上就没有偏差(误差)。
在图3中，阀门用来控制进入加热器的气体，冷却器的制冷，水管的压力，水管的流量，容器的水位或其他的过程控制系统。
PID控制器所观察的是PV和SP之间的偏差(或误差)。
它观察绝对偏差和偏差变换率。
绝对偏差就是'PV和SP之间偏差是大还是小。
偏差变换率就是——PV和SP之间的偏差随着时间的变化是越来越小还是越来越大。
SETPOINT P，I，&DCONSTANTSDifference error PID controlalgorithmprocess outputvariable图3 PID控制器如果存在过程扰动，即过程变量或基准点迅速变化时，PID控制器就要迅速改变输出，使过程变量快速返回到基准点。
如果你有一个PID控制的可进入的冷冻装置，某个人打开门进入，温度（过程变量）将会迅速升高。
因此，PID控制器不得不提高冷却(输出)来补偿这个温度的升高。
一旦过程变量等同于基准点，一个好的PID控制器就不会改变输出。
你所要的输出是非常稳定的(不会改变)。
如果阀门(发动机或其他控制器件)不断改变，而不是维持恒量，这将造成控制元件更多的磨损。
这样就有了两个矛盾的目标。
当有“过程扰动”时能够快速反应（快速改变输出）。
当PV接近基准点时就缓慢反应（平稳输出）。
我们注意到输出量经常超过稳定状态输出使过程变量回到基准点。
比如，一个制冷器通常打开它的制冷阀门的34％，就可以维持在零度（在制冷器关闭和温度降低后）。
如果某人打开制冷器，走进去，四处走，找东西，然后再走出来，再关上制冷器的门，PID控制器会非常活跃，因为温度可能将上升20度。
这样制冷阀门就可能打开50％，75％甚至100％，目的是赶快降低制冷器的温度，然后慢慢关闭制冷阀门回到它的34％。
让我们来考虑一下如何设计一个PID控制器。
我们主要集中在过程变量(PV)和基准点(SP)之间的偏差(误差)上。
有三种定义误差的方式。
绝对偏差他说明的是PV和SP之间的偏差有多大。
如果PV和SP之间偏差小，那我们就在输出时作一个小的改变。
如果PV和SP之间偏差大——那我们就在输出时作一个大的改变。
绝对偏差就是PID控制器的比例环节。
累积误差给我们点时间，我们将会明白为什么仅仅简单地观察绝对偏差(比例环节)是一个问题。
累积误差是很重要的，我们把它称为是PID控制器的积分环节。
每次我们运行PID算法时，我们总会把最近的误差添加到误差总和中。
换句话说，累积误差，误差1+误差2+误差3+误差4+……滞后时间滞后时间指的是PV引起的变化由发现到改变之间的延时。
典型的例子就是调整你的烤炉在合适的温度。
当你刚刚开始加热，烤炉热起来需要一定时间，这就是滞后时间。
如果你设置一个初始温度，等待烤炉达到这个初始温度，然后你认为你设定了错误的温度，烤炉达到这个新的温度基准点还需要一段时间。
这也被认为是PID控制器的微分环节。
这就抑制了某些将来的变化因为输出值已经发生了改变，但并不是受过程变量的影响。
附件2：外文原文（复印件）Introductions to temperature controland PID controllersProcess control system.Automatic process control is concerned with maintaining process variables temperatures pressures flows compositions, and the like at some desired operation value. Processes are dynamic in nature. Changes are always occurring, and if actions are nottaken, the important process variables-those related to safety, product quality, and production rates-will not achieve design conditions.In order to fix ideas, let us consider a heat exchanger in which a process stream is heated by condensing steam. The process is sketched in Fig.1Fig. 1 Heat exchangerThe purpose of this unit is to heat the process fluid from some inlet temperature, Ti(t), up to a certain desired outlet temperature, T(t). As mentioned, the heating medium is condensing steam.The energy gained by the process fluid is equal to the heat released by the steam,provided there are no heat losses to surroundings, that is, the heat exchanger and piping are well insulated.In this process there are many variables that can change, causing the outlet temperature to deviate from its desired value. If this happens, some action must be taken to correct for this deviation. That is, the objective is to control the outlet process temperature to maintain its desired value.One way to accomplish this objective is by first measuring the temperature T(t) , then comparing it to its desired value, and, based on this comparison, deciding what to do to correct for any deviation. The flow of steam can be used to correct for the deviation. This is, if the temperature is above its desired value, then the steam valve can be throttled back to cut the steam flow (energy) to the heat exchanger. If the temperature is below its desired value, then the steam valve could be opened some more to increase the steam flow (energy) to the exchanger. All of these can be done manually by the operator, and since the procedure is fairly straightforward, it should present no problem. However, since in most process plants there are hundreds of variables that must be maintained at some desired value, this correction procedure would required a tremendous number of operators. Consequently, we would like to accomplish this control automatically. That is, we want to have instuments that control the variables without intervention from the operator. This is what we mean by automatic process control.To accomplish this objective a control system must be designed and implemented. A possible control system and its basic components are shown in Fig.2.Fig. 2 Heat exchanger control loopThe first thing to do is to measure the outlet temperature of the process stream. A sensor (thermocouple, thermistors, etc) does this. This sensor is connected physically to a transmitter, which takes the output from the sensor and converts it to a signal strong enough to be transmitter to a controller. The controller then receives the signal, which is related to the temperature, and compares it with desired value. Depending on this comparison, the controller decides what to do to maintain the temperature at its desired value. Base on this decision, the controller then sends another signal to final control element, which in turn manipulates the steam flow.The preceding paragraph presents the four basic components of all control systems. They are(1) sensor, also often called the primary element.(2) transmitter, also called the secondary element.(3) controller, the "brain" of the control system.(4) final control system, often a control valve but not always. Other common final control elements are variable speed pumps, conveyors, and electric motors.The importance of these components is that they perform the three basic operations that must be present in every control system. These operations are(1) Measurement（M）: Measuring the variable to be controlled is usually done bythe combination of sensor and transmitter.(2) Decision (D): Based on the measurement, the controller must then decide what to do to maintain the variable at its desired value.(3) Action (A): As a result of the controller's decision, the system must then take an action. This is usually accomplished by the final control element.As mentioned, these three operations, M, D, and A, must be present in every control system.PID controllers can be stand-alone controllers (also called single loop controllers), controllers in PLCS, embedded controllers, or software in Visual Basic or C# computer programs.PID controllers are process controllers with the following characteristics:Continuous process controlAnalog input (also known as "measurement" or "Process Variable" or "PV")Analog output (referred to simply as "output")Setpoint (SP)Proportional (P), Integral (I), and/or Derivative (D) constantsExamples of "continuous process control" are temperature, pressure, flow, and level control. For example, controlling the heating of a tank. For simple control, you have two temperature limit sensors (one low and one high) and then switch the heater on when the low temperature limit sensor turns on and then turn the heater off when the temperature rises to the high temperature limit sensor. This is similar to most home air conditioning & heating thermostats.In contrast, the PID controller would receive input as the actual temperature and control a valve that regulates the flow of gas to the heater. The PID controller automatically finds the correct (constant) flow of gas to the heater that keeps the temperature steady at the setpoint. Instead of the temperature bouncing back and forth between two points, the temperature is held steady. If the setpoint is lowered, then the PID controller automatically reduces the amount of gas flowing to the heater. If the setpoint is raised, then the PID controller automatically increases the amount of gas flowing to the heater. Likewise the PID controller would automatically for hot, sunnydays (when it is hotter outside the heater) and for cold, cloudy days.The analog input (measurement) is called the "process variable" or "PV". You want the PV to be a highly accurate indication of the process parameter you are trying to control. For example, if you want to maintain a temperature of + or - one degree then we typically strive for at least ten times that or one-tenth of a degree. If the analog input is a 12 bit analog input and the temperature range for the sensor is 0 to 400 degrees then our "theoretical" accuracy is calculated to be 400 degrees divided by 4,096 (12 bits) =0.09765625 degrees. We say "theoretical" because it would assume there was no noise and error in our temperature sensor, wiring, and analog converter. There are other assumptions such as linearity, etc. The point being--with 1/10 of a degree "theoretical" accuracy--even with the usual amount of noise and other problems-- one degree of accuracy should easily be attainable.The analog output is often simply referred to as "output". Often this is given as 0~100 percent. In this heating example, it would mean the valve is totally closed (0%) or totally open (100%).The setpoint (SP) is simply--what process value do you want. In this example--what temperature do you want the process at?The PID controller's job is to maintain the output at a level so that there is no difference (error) between the process variable (PV) and the setpoint (SP).In Fig. 3, the valve could be controlling the gas going to a heater, the chilling of a cooler, the pressure in a pipe, the flow through a pipe, the level in a tank, or any other process control system. What the PID controller is looking at is the difference (or "error") between the PV and the SP.SETPOINT P，I，&DCONSTANTSDifference error PID controlalgorithmprocess outputvariableFig .3 PIDcontrolIt looks at the absolute error and the rate of change of error. Absolute error means--is there a big difference in the PV and SP or a little difference? Rate of change of error means--is the difference between the PV or SP getting smaller or larger as time goes on.When there is a "process upset", meaning, when the process variable or the setpoint quickly changes--the PID controller has to quickly change the output to get the process variable back equal to the setpoint. If you have a walk-in cooler with a PID controller and someone opens the door and walks in, the temperature (process variable) could rise very quickly. Therefore the PID controller has to increase the cooling (output) to compensate for this rise in temperature.Once the PID controller has the process variable equal to the setpoint, a good PID controller will not vary the output. You want the output to be very steady (not changing) . If the valve (motor, or other control element) is constantly changing, instead of maintaining a constant value, this could cause more wear on the control element.So there are these two contradictory goals. Fast response (fast change in output) when there is a "process upset", but slow response (steady output) when the PV is close to the setpoint.Note that the output often goes past (over shoots) the steady-state output to get the process back to the setpoint. For example, a cooler may normally have its cooling valve open 34% to maintain zero degrees (after the cooler has been closed up and the temperature settled down). If someone opens the cooler, walks in, walks around to find something, then walks back out, and then closes the cooler door--the PID controller is freaking out because the temperature may have raised 20 degrees! So it may crank the cooling valve open to 50, 75, or even 100 percent--to hurry up and cool the cooler back down--before slowly closing the cooling valve back down to 34 percent.Let's think about how to design a PID controller.We focus on the difference (error) between the process variable (PV) and thesetpoint (SP). There are three ways we can view the error.The absolute errorThis means how big is the difference between the PV and SP. If there is a small difference between the PV and the SP--then let's make a small change in the output. If there is a large difference in the PV and SP--then let's make a large change in the output. Absolute error is the "proportional" (P) component of the PID controller.The sum of errors over timeGive us a minute and we will show why simply looking at the absolute error (proportional) only is a problem. The sum of errors over time is important and is called the "integral" (I) component of the PID controller. Every time we run the PID algorithm we add the latest error to the sum of errors. In other words Sum of Errors = Error 1 q- Error2 + Error3 + Error4 +…The dead timeDead time refers to the delay between making a change in the output and seeing the change reflected in the PV. The classical example is getting your oven at the right temperature. When you first turn on the heat, it takes a while for the oven to "heat up". This is the dead time. If you set an initial temperature, wait for the oven to reach the initial temperature, and then you determine that you set the wrong temperature--then it will take a while for the oven to reach the new temperature setpoint. This is also referred to as the "derivative" (D) component of the PID controller. This holds some future changes back because the changes in the output have been made but are not reflected in the process variable yet.。