亲 外文你可以在知网上找啊 外文有什么要求 和题目相关吗
嗯，，可行的，找我
参考资料：-/Chinasupplier/Web_Photo/62044/pdf
空调压缩机过载保护的研究321前言空调器压缩机易受电压、制冷系统工况的影响，在不良的使用环境中，压缩机容易烧毁。作为空调器成本最高的部件，压缩机的保护技术成为空调技术领域必须关注的一个重要课题。在现有的压缩机的保护技术中使用最多的是用电流互感器或温度传感器检测技术，前者是利用电流互感器感应压缩机主电路的电流，通过电流的检测获知压缩机电流，当电流超过设定值时，通过软件的控制断开主回路保护压缩机，电流互感器可以装在室内机或室外机中；温度传感器检测技术是在压缩机的表面安装一个温度传感器，通过检测压缩机的温度来保护压缩机，由于压缩机线圈在内部，其表面与外部的温升相差甚远，温度测量误差较大，在瞬间的过流中，保护效果不理想。以上两种技术需要单片机控制，而且在室内机与室外机之间要增加一至两条连接线，制造成本较高。从有关的实验中发现，压缩机烧毁往往出现在缺少制冷剂并在恶劣的使用环境工况下，压缩机线圈温度与进气压力、制冷剂的数量有关。本文主要讨论在常用的空调器室内机的软件、硬件不变的情况下，利用压力开关作为压力检测器件，在室外机的闲置的空间增加一个检测的电控板，通过对压缩机的压力检测实现压缩机的过载保护。采用这种方案，无需对空调器的原有电路进行更改，通用性极强，可应用于不同型号的空调器，而且室内机无需变化。2控制方案及实现方法1电路原理压缩机压力检测电路原理包括：在压缩机的进气管安装压力开关，以及在室外机安装一个电控板，电控板主要包含5个部分：阻容降压电路、压缩机延时电路、外风机转换电路、压力开关转换电路、三极管控制电路，利用压缩机、外风机、压力开关的信号，通过硬件电路自动实现压缩机进气压力过低等不正常的压力保护，在保护的过程中，不影响空调的启动和空调的除霜。图1为压缩机保护装置检测结构方框图，图2为压缩机保护装置电气原理图。阻容降压电路主要由电阻、电容、压敏电阻、稳压二极管组成，输入端与压缩机线相连接，其作用是将220V的交流电转为低压的12V直流电，作为各电路的供电电源，输出端的12V供给比较器及其偏图1压缩机保护装置检测结构方框原理图置电路、三极管、压力开关等器件，阻容降压电路省略了变压器，成本极低。压缩机延时电路。该电路是保证压缩机运行的前5分钟能正常运行，由于压缩机刚开启的头3分钟，进气管的压力偏低，压力开关打开，压力开关转换电路会出现低压保护信号。压缩机延时电路与压力开关转换电路为并联关系，图3为压缩机延时电路控制逻辑示意图。压缩机开启后，阻容降压电路输出12V供给压缩机延时电路，由于C 3 0 7正在充电，IC304A的2脚输出低电平，当压缩机得电后约5分钟，C307充满电，IC304A的2脚输出由低电平转为高电平，这样压缩机延时电路相当于一个延时5分钟的开关，在压缩机开启头5分钟闭合，超过5分钟后打开，这样保证了压缩机开启的头3分钟能正常运行。外风机转换电路：压缩机除霜时间一般为8至10分钟（如图2），大功率的压缩机除霜期间，进气口处于低压力的时间较长，致使压力开关打开，然而压缩机延时电路只能延时5分钟，这样会出现压缩机除霜超过5分钟后不能除霜的现象，所以需要加入一个外风机转换电路。以比较器芯片为主构成的外风机转换电路相当一个非门电路，图4为外风机转换电路控制逻辑示意图。当外风机线得电时，转换电路输出为高电平；反之转换电路输出为低电平。正常的制热或制冷工况下，外风机得电，IC303光耦PC817导通，IC305C的14脚为高电平；在除霜期间外风机关闭，IC303光耦PC817截止，IC305C的14脚为低电平，这时不论压力开关转换电路处于何种工作状态，压缩机仍可运。压力开关转换电路。将压力开关的进气孔和出气孔串接在压缩机低压的进气管路中，当制冷剂泄漏造成不足，且空调器运行在恶劣的环境工况中，造成压力过低时，压力开关打开，反之，压力开关闭合，有图与我索取全文免费
主要课程 工程力学、工程流体力学、工程热力学、传热学、物理化学、泵与压缩机、电工与电子技术、油气管道设计与管理、油气集输、油库设计与管理等。 主要实践性教学环节 包括工程制图、测量实习、金工实习、施工实习等，一般安排18周。 业务培养要求 本专业学生主要学习油气储运工艺、设备与设施方面的基本理论和基本知识，受到识图制图、上机操作、工程测量、工程概预算的基本训练，具有进行油气储运系统的规划、设计与运行管理的基本能力。 毕业生应获得的知识与能力 1．掌握工程流体力学、工程热力学、传热学、物理化学和化工过程方面的基本理论和基本知识。 掌握油气质量检测、油气储运设备的防腐与安全保障技术。 3．具有油气储运系统的规划、设计与运行管理的初步能力。 4．熟悉油气储运行业的方针、政策和法规。 5．了解油气储运工程的理论前沿和发展动态。 6．掌握文献检索、资料查询的基本方法，具有初步的科学研究和实际工作能力。 就业方向 本专业培养具备工程流体力学、物理化学、油气储运工程等方面知识，能在国家与省、市的发展计划部门、交通运输规划与设计部门、油气储运管理部门等从事油气储运工程的规划、勘查设计、施工项目管理和研究、开发等工作的高级工程技术人才。
学术论文具有四大特点：①学术性 ②科学性 ③创造性 ④理论性一、学术性学术论文的科学性，要求作者在立论上不得带有个人好恶的偏见，不得主观臆造，必须切实地从客观实际出发，从中引出符合实际的结论。在论据上，应尽可能多地占有资料，以最充分的、确凿有力的论据作为立论的依据。在论证时，必须经过周密的思考，进行严谨的论证。二、科学性科学研究是对新知识的探求。创造性是科学研究的生命。学术论文的创造性在于作者要有自己独到的见解，能提出新的观点、新的理论。这是因为科学的本性就是“革命的和非正统的”，“科学方法主要是发现新现象、制定新理论的一种手段，旧的科学理论就必然会不断地为新理论推翻。”（斯蒂芬·梅森）因此，没有创造性，学术论文就没有科学价值。三、创造性学术论文在形式上是属于议论文的，但它与一般议论文不同，它必须是有自己的理论系统的，不能只是材料的罗列，应对大量的事实、材料进行分析、研究，使感性认识上升到理性认识。一般来说，学术论文具有论证色彩，或具有论辩色彩。论文的内容必须符合历史 唯物主义和 唯物辩证法，符合“实事求是”、“有的放矢”、“既分析又综合” 的科学研究方法。四、理论性指的是要用通俗易懂的语言表述科学道理，不仅要做到文从字顺，而且要准确、鲜明、和谐、力求生动。表论文的过程 投稿-审稿-用稿通知-办理相关费用-出刊-邮递样刊 一般作者先了解期刊，选定期刊后，找到投稿方式，部分期刊要求书面形式投稿。大部分是采用电子稿件形式。 发表论文审核时间 一般普通刊物（省级、国家级）审核时间为一周，高质量的杂志，审核时间为14-20天。 核心期刊审核时间一般为4个月，须经过初审、复审、终审三道程序。 期刊的级别问题 国家没有对期刊进行级别划分。但各单位一般根据期刊的主管单位的级别来对期刊划为省级期刊和国家级期刊。省级期刊主管单位是省级单位。国家级期刊主管单位是国家部门或直属部门。
建议看看下面的资料网，在这里想要谁给现写一篇，可能不会有，因为z这里没人会为了这个区花费一些时间去写的，所以根据我搜集的一些网站来看，希望对你有所帮助，用心去做，不管毕业论文还是平时作业吗，我相信你都可以做好的。毕业论文以及毕业设计的，推荐一个网 这个网站的论文都是以words的形式原封不动的打包上传的，网上搜索不到的，对毕业论文的写作有很大的参考价值，希望对你有所帮助。 论文写作建议看看下面的资料网，在这里想要谁给现写一篇，可能不会有，因为z这里没人会为了这个区花费一些时间去写的，所以根据我搜集的一些网站来看，希望对你有所帮助，用心去做，不管毕业论文还是平时作业吗，我相信你都可以做好的。写作资料也很多，下面给你一些范文资料网： 如果你不是校园网的话，请在下面的网站找： 百万范文网： 分类很细 栏目很多 毕业论文网： 引文数据库： 社科类论文： 经济类论文： 论文之家： 范文网： 如果你是校园网，那就恭喜你了，期刊网里面很多资料 中国知网： 龙源数据库： 万方数据库： 优秀论文杂志 论文资料网 法律图书馆 -/z 法学论文资料库 -/lw/ 中国总经理网论文集 职业经理人论坛 财经学位论文下载中心 公开发表论文_深圳证券交易所 中国路桥资讯网论文资料中心 论文商务中心 ' 法律帝国： 学术论文 论文统计
The Basics A jet engine can be divided into several distinct sections: intake, compressor, diffuser, combustion chamber, turbine, and These sections are much like the different cycles in a four-stroke reciprocating engine: intake, compression, power and In a four-stroke engine a fuel/air mixture is is brought into the engine (intake), compressed (compression), and finally ignited and pushed out the exhaust (power and exhaust) In it's most basic form, a jet engine works in much the same * Air comes in the front of the engine where it enters the The air is compressed by a series of small spinning blades aptly named compressor blades and leaves at a high The pressure ratio between the beginning and end of the compressor can be as much as 48:1, but almost always 12:1 or * The air now enters the diffuser, which is nothing more than an area where the air can expand and lower it's velocity, thus increasing its pressure a little bit * The high pressure air at the end of the diffuser now enters the combustion chamber where it is mixed with fuel, ignited and * When the fuel/air mixture burns, the temperature increases (obviously) which makes the air * This expanding gas drives a set of turbine blades located aft of the combustion At least some of these turbine blades are connected by a shaft to the compressor blades to drive Depending on the type of engine, there may be another set of turbine blades used to drive another shaft to do other things, such as turn a propeller or * The left over energy not extracted by the turbine blades is pushed out the back of the engine (exhaust section) and creates thrust, usually used to drive an airplane The types of jet engines include: * Turbojet * Turbofan * Turboprop * Turbo shaft Turbojet The turbojet is the simplest of them all, it is just as described in "The basics" This style was the first type of jet engine to be used in It is a pretty primitive style used mostly in early military jet fighters such as the F- Its use was discontinued, for the most part, in favor of the more efficient Actually, I should clarify Each type of engine is most efficient under certain Turbojets are most efficient at high altitudes and speeds above the speed of See the diagram at the end of this page for relative efficiencies of each style Turbofan Turbofans make up the majority of jet engines being produced and used A turbofan engine uses an extra set of turbine blades to drive a large fan, typically on the front of the This fan differs from a propeller in that there are many small blades and they are inside of a The fan sits just in front of the normal intake, some of the air driven by this fan will enter the engine, while the rest will go around the The amount of air that bypasses the engine is different for each type of The different styles are called high and low bypass Bypass ratio is the ratio of how much air goes through the fan, to how much goes through the Typical bypass ratios would be 1:1 for a low bypass and 5:1 or more for a high Low bypass engines are more efficient at higher speeds, and are used on planes such as military aircraft, while high bypass engines are used in commercial Turboprop Turboprops are similar to turbofans in that they incorporate an extra set of turbine blades used to drive the Unlike the turbofan engines, nearly all the thrust produced by a turboprop is from the propellor, hardly any thrust comes from the These engines are used mostly on smaller and slower planes such as commuter aircraft that fly to the smaller As you can see from the efficiency chart below, turboprops are very efficient over a fairly wide range of They would probably be used more often on large transport aircraft, except for one problem: they have The general public does not like propellors, as they appear to be old-fashioned and However, the military knows better and uses them on several large transport Turbo shaft Turbo shaft engines are very similar to turboprop engines, but instead of driving a propellor, they are used to drive something Many helicopters use them to drive their rotors, and airliners and other large jets use them to generate Also, the Alaska Pipeline uses them at the pump stations to pump Overall Overall the big difference between these engines is how they take a chunk of air and move Newton's third law states that Force equals mass times Applying this to turbine engines: the turboprop takes a large chunk and accelerates it a little bit, while the turbojet takes a small chunk and accelerates the heck out of it, and the turbofan is somewhere in between these These different methods of moving air also have to do with how much noise each engine The turbojet makes the most noise because there is a large difference in velocities of the blast of air coming out the exhaust and the surrounding The air from the fan on a turbofan engine "shields" the blast in the center by having the slower moving air from the fan surround Then the turboprop is the quietest of all because the air it's moving is relatively A pressure - volume diagram (or a P-V diagram) is a useful tool in In this case, it relates the pressure and volume of the gas moving through the engine at different A P-V diagram can also be helpful in finding the work output of an Work equals the integral of pressure with respect to Or is simpler form, work equals the area enclosed in the diagram The above cycle is the Brayton cycle, or the cycle used by aircraft gas turbine Explanation of the above cycle: * Air enters the inlet at point 1 at atmospheric * As this air passes through the compressor (from point 1 to 2), the pressure rises adiabatically (no heat enters or leaves the system) * Now the air enters the combustion chamber (from point 2 to 3), is mixed with fuel, and burned at a constant * Finally, the air goes through the turbine and out the exhaust (point 3 to 4) where the gases expand and do Thus, the pressure drops and the volume The Compressor There are two main styles for turbine compressors: the axial and the The Axial Compressor * The axial type compressor is made up of many small blades, called rotor vanes, arranged in rows on a cylinder whose radius gets larger towards the back (as can be seen from the above picture) These blades act much like small * In between these rotor vanes are stator vanes which stay in a fixed spot and straighten the air coming out of the previous stage of rotor vanes before it enters the next * On some newer engines, the angle of these stator vanes can be adjusted for optimum * Each stage (1 row of rotor and stator vanes) generally provides for a pressure rise of about 3:1 (so after the first stage, the pressure would be 3 above atmospheric, after the second it would be 69, 2, ) The Centrifugal Compressor * Air enters the centrifugal compressor at the front and The blades then sling the air radially outwards where it is once again collected (at a higher pressure) before it enters the * Pressure rise per stage is usually about 4 to 8:1 (higher than axial) These can be sombined in series (that is the exit of the first leads to the entrance of the next) to produce a greater pressure But more than two stages is not - Jet engines are rated in "pounds of thrust," while turboprops and turboshaft engines are rated in "shaft horsepower" (SHP) This is because it is difficult to hook up a dynamometer (power measuring device) to the column of air coming out of a jet engine, while it is easy to hook one to the shaft of a - An equivalent measure to horsepower is thrust horsepower (THP) THP = (Thrust x MPH) / or THP = SHP x 80% in the case of turboprop engines (the 80% is because the propeller "slips" a little in flight) - Exhaust gases exit the exhaust at upwards of 1000 mph or more and can use 1000 gallons of fuel/hour or - Turbine engines run Unlike gasoline engines, turbines take in more air than they need for - Fuel can be injected into the exhaust section to burn with this unused air for extra This is called an - A water/methanol mixture can be injected into the intake to increase the air density, and thus increase - Turbine engines can be built on a small scale as The turbine pictured below has a diameter of 4mm and runs at 500,000 It was built by at MIT for purposes of powering an aircraft with a wing span of about 5 inches that was projected to fly about 35 - 70 mph with a range of about 40 - 70 micro turbine - The ignition system on turbine engines is only necessary for starting, afterwards it is self In jets, the ignition system is also turned on for added saftey in "critical" stages of flight, such as takeoff and - A device similar to a spark plug is used for the ignition process, but it has a larger The spark is about 4 to 20 Joules (watts/second) at about 25000 volts and occurs between 1 and 2 times per - Turbine engines will run on just about anything, they prefer Jet-A (AKA diesel, kerosene, or home heating oil), but can burn unleaded, burbon, or even very finely powdered coal! - The above snowmachine uses an Allison turbine engine, a very common engine in helicopters (such as the Bell 206 Jet Ranger shown below) A lot of horsepower can be put into a small package! Note the intake and compressor are at the front of the engine, then the two side tubes take the compressed air and bring it around back to the combustion chamber and turbine and the exhaust exits out the There are many engines out there with strange configurations like Communications Technology Your Rights and what the Data Protection Commissioner can do to help Right of Access The personal information to which you are entitled is that held on computer or in a manual filing system that facilitates access to information about You can make an access request to any organisation or any individual who has personal information about For example, you could make an access request to your doctor, your bank, a credit reference agency, a Government Department dealing with your affairs, or your If you find out that information kept about you by someone else is inaccurate, you have a right to have that information corrected (or "rectified") In some circumstances, you may also have the information erased altogether from the database - for example, if the body keeping the information has no good reason to hold it ( it is irrelevant or excessive for the purpose), or if the information has not been obtained You can exercise your right of rectification or erasure simply by writing to the body keeping your In addition, you can request a data controller to block your data to prevent it from being used for certain For example, you might want your data blocked for research purposes where it held for other If an organisation holds your information for the purposes of direct marketing (such as direct mailing, or telephone marketing), you have the right to have your details removed from that This right is useful if you are receiving unwanted "junk mail" or annoying telephone calls from You can exercise this right simply by writing to the organisation The organisation must write back to you within 40 days confirming that they have dealt with your Right to complain to the Data Protection Commissioner What happens if someone ignores your access request, or refuses to correct information about you which is inaccurate? If you are having difficulty in exercising your rights, or if you feel that any person or organisation is not complying with their responsibilities, then you may complain to the Data Protection Commissioner, Mr Mead, who will investigate the matter for The Commissioner has legal powers to ensure that your rights are The Data Protection Commissioner will help you to secure your rights: * with advice and information * by intervening directly on your behalf if you feel you have not been given satisfaction * by taking action against those failing to fulfil their SEE APPENDIX 2 FOR CASE STUDY Ergonomics Ergonomics (from Greek ergon work and nomoi natural laws) is the study of designing objects to be better adapted to the shape of the human body and/or to correct the user's Common examples include chairs designed to prevent the user from sitting in positions that may have a detrimental effect on the spine, and the ergonomic desk which offers an adjustable keyboard tray, a main desktop of variable height and other elements which can be changed by the Ergonomics also helps with the design of alternative computer input devices for people who want to avoid repetitive strain injury or carpal tunnel A normal computer keyboard tends to force users to keep their hands together and hunch their To prevent the injuries, or to give relief to people who already have symptoms, special split keyboards, curved keyboards, not-really-keyboards keyboards, and other alternative input devices Ergonomics is much larger than looking at the physiological and anatomical aspects of the human The psychology of humans is also a key element within the ergonomics This psychological portion of ergonomics is usually referred to as Human factors or Human factors engineering in the US, and ergonomics is the term used in E Understanding design in terms of cognitive workload, human error, the way humans perceive their surrounds and, very importantly, the tasks that they undertake are all analysed by [IMAGE] With video conferencing consideration should be taken in positioning of camera and screens so as to avoid neck Codec (COder/DECoder or COmpressor/DECompressor) Hardware or software that encodes/compresses and decodes/decompresses audio and video data The purpose of a codec is to reduce the size of digital audio samples and video frames in order to speed up transmission and save storage The goal of all codec designers is to maintain audio and video quality while compressing the binary data Speech codecs are designed to deal with the characteristics of voice, while audio codecs are developed for Codecs may also be able to transcode from one digital format to another; for example, from PCM audio to MP3 The codec algorithms may be implemented entirely in a chip or entirely in software in which case the PC does all of the They are also commonly implemented in both hardware and software where a sound card or video capture card performs some of the processing, and the main CPU does the When analog signals are entered into a computer, cellphone or other device via a microphone or video source such as a VHS tape or TV, analog-to-digital converters create the raw digital audio samples and video Speech, audio and video codecs are typically lossy codecs that compress data by altering the original format, which is why "codec" means "encoder/decoder" and "compressor/" If a codec uses only lossless compression in which the original data is restored exactly, then it would not be a coder/ This is a subtle point, but the two meanings of the acronym have been LAN A local area network (LAN) is a computer network covering a local area, like a home, office or small group of buildings such as a The topology of a network dictates its physical The generally accepted maximum size for a LAN is LANs are different from personal area networks (PANs), metropolitan area networks (MANs) or wide area networks (WANs) LANs are typically faster than WAN The earliest popular LAN, ARCnet, was released in 1977 by Datapoint and was originally intended to allow multiple Datapoint 2200s to share disk Like all early LANs, ARCnet was originally vendor- Standardization efforts by the IEEE have resulted in the IEEE 802 series of There are now two common wiring technologies for a LAN, Ethernet and Token R Wireless technologies are starting to evolve and are convenient for mobile computer A number of network protocols may use the basic physical transport mechanism including TCP/IP In this case DHCP is a convenient way to obtain an IP address rather than using fixed LANs can be interlinked by connections to form a Wide area A router is used to make the connection between LAN WAN WANs are used to connect local area networks together, so that users and computers in one location can communicate with users and computers in other Many WANs are built for one particular organisation and are private, others, built by Internet service providers provide connections from an organisation's LAN to the I WANs are most often built of leased At each end of the leased line, a router connects to the LAN on one side and a hub within the WAN on the A number of network protocols may use the basic physical transport mechanism including TCP/IP Other protocols including X25 and ATM Frame relay can also be used for WAN Ethernet Ethernet is normally a shared media LAN All stations on the segment share the total bandwidth, which is either 10 Mbps (Ethernet), 100 Mbps (Fast Ethernet) or 1000 Mbps (Gigabit Ethernet) With switched Ethernet, each sender and receiver pair have the full When using Ethernet the computers are usually wired to a hub or to a This constitutes the physical transport Fiber-optic Ethernet (10BaseF and 100BaseFX) is impervious to external radiation and is often used to extend Ethernet segments up to 2 Specifications exist for complete fiber-optic networks as well as backbone FOIRL (Fiber-Optic Inter Repeater Link) was an earlier standard that is limited to 6 miles
一：1、题目。应能概括整个论文最重要的内容，言简意赅，引人注目，一般不宜超过20个字。 论文摘要和关键词。2、论文摘要应阐述学位论文的主要观点。说明本论文的目的、研究方法、成果和结论。尽可能保留原论文的基本信息，突出论文的创造性成果和新见解。而不应是各章节标题的简单罗列。摘要以500字左右为宜。 关键词是能反映论文主旨最关键的词句，一般3-5个。3、目录。既是论文的提纲，也是论文组成部分的小标题，应标注相应页码。4、引言(或序言)。内容应包括本研究领域的国内外现状，本论文所要解决的问题及这项研究工作在经济建设、科技进步和社会发展等方面的理论意义与实用价值。5、正文。是毕业论文的主体。6、结论。论文结论要求明确、精炼、完整，应阐明自己的创造性成果或新见解，以及在本领域的意义。7、参考文献和注释。按论文中所引用文献或注释编号的顺序列在论文正文之后，参考文献之前。图表或数据必须注明来源和出处。(参考文献是期刊时，书写格式为：[编号]、作者、文章题目、期刊名(外文可缩写)、年份、卷号、期数、页码。 参考文献是图书时，书写格式为：[编号]、作者、书名、出版单位、年份、版次、页码。)8、附录。包括放在正文内过份冗长的公式推导，以备他人阅读方便所需的辅助性数学工具、重复性数据图表、论文使用的符号意义、单位缩写、程序全文及有关说明等。
留个邮箱，我有一些资料，可以发给你
有很多写的。工艺，技术，未来的趋势等。