毕设外文翻译(译文)封面
毕业设计中英文翻译【范本模板】
英文The road (highway)The road is one kind of linear construction used for travel。
It is made of the roadbed，the road surface, the bridge, the culvert and the tunnel. In addition, it also has the crossing of lines, the protective project and the traffic engineering and the route facility。
The roadbed is the base of road surface, road shoulder，side slope, side ditch foundations. It is stone material structure, which is designed according to route's plane position .The roadbed, as the base of travel, must guarantee that it has the enough intensity and the stability that can prevent the water and other natural disaster from corroding.The road surface is the surface of road. It is single or complex structure built with mixture。
The road surface require being smooth，having enough intensity，good stability and anti—slippery function. The quality of road surface directly affects the safe, comfort and the traffic。
毕业设计外文翻译译文
1 工程概论1.1 工程专业1.2 工业和技术1.3 现代制造业工程专业1 工程行业是历史上最古老的行业之一。
如果没有在广阔工程领域中应用的那些技术，我们现在的文明绝不会前进。
第一位把岩石凿削成箭和矛的工具匠是现代机械工程师的鼻祖。
那些发现地球上的金属并找到冶炼和使用金属的方法的工匠们是采矿和冶金工程师的先祖。
那些发明了灌溉系统并建造了远古世纪非凡的建筑物的技师是他们那个时代的土木工程师。
2 工程一般被定义为理论科学的实际应用，例如物理和数学。
许多早期的工程设计分支不是基于科学而是经验信息，这些经验信息取决于观察和经历，而不是理论知识。
这是一个倾斜面实际应用的例子，虽然这个概念没有被确切的理解，但是它可以被量化或者数字化的表达出来。
3 从16、17世纪当代初期，量化就已经成为科学知识大爆炸的首要原因之一。
另外一个重要因素是实验法验证理论的发展。
量化包含了把来源于实验的数据和信息转变成确切的数学术语。
这更加强调了数学是现代工程学的语言。
4 从19世纪开始，它的结果的实际而科学的应用已经逐步上升。
机械工程师现在有精确的能力去计算来源于许多不同机构之间错综复杂的相互作用的机械优势。
他拥有能一起工作的既新型又强硬的材料和巨大的新能源。
工业革命开始于使用水和蒸汽一起工作。
从此使用电、汽油和其他能源作动力的机器变得如此广泛以至于它们承担了世界上很大比例的工作。
5 科学知识迅速膨胀的结果之一就是科学和工程专业的数量的增加。
到19世纪末不仅机械、土木、矿业、冶金工程被建立而且更新的化学和电气工程专业出现了。
这种膨胀现象一直持续到现在。
我们现在拥有了核能、石油、航天航空空间以及电气工程等。
每种工程领域之内都有细分。
6 例如，土木工程自身领域之内有如下细分：涉及永久性结构的建筑工程、涉及水或其他液体流动与控制系统的水利工程、涉及供水、净化、排水系统的研究的环境工程。
机械工程主要的细分是工业工程，它涉及的是错综复杂的机械系统，这些系统是工业上的，而非单独的机器。
毕业设计(论文)外文原文及译文
毕业设计（论文）外文原文及译文一、外文原文MCUA microcontroller (or MCU) is a computer-on-a-chip. It is a type of microcontroller emphasizing self-sufficiency and cost-effectiveness, in contrast to a general-purpose microprocessor (the kind used in a PC).With the development of technology and control systems in a wide range of applications, as well as equipment to small and intelligent development, as one of the single-chip high-tech for its small size, powerful, low cost, and other advantages of the use of flexible, show a strong vitality. It is generally better compared to the integrated circuit of anti-interference ability, the environmental temperature and humidity have better adaptability, can be stable under the conditions in the industrial. And single-chip widely used in a variety of instruments and meters, so that intelligent instrumentation and improves their measurement speed and measurement accuracy, to strengthen control functions. In short，with the advent of the information age, traditional single- chip inherent structural weaknesses, so that it show a lot of drawbacks. The speed, scale, performance indicators, such as users increasingly difficult to meet the needs of the development of single-chip chipset, upgrades are faced with new challenges.The Description of AT89S52The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of In-System Programmable Flash memory. The device is manufactured using Atmel's high-density nonvolatile memory technology and is compatible with the industry-standard 80C51 instruction set and pinout. 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 Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications.The AT89S52 provides the following standard features: 8K bytes ofFlash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S52 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 system to continue functioning. The Power-down mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset.Features• Compatible with MCS-51® Products• 8K Bytes of In-System Programmable (ISP) Flash Memory– Endurance: 1000 Write/Erase Cycles• 4.0V to 5.5V Operating Range• Fully Static Operation: 0 Hz to 33 MHz• Three-level Program Memory Lock• 256 x 8-bit Internal RAM• 32 Programmable I/O Lines• Three 16-bit Timer/Counters• Eight Interrupt Sources• Full Duplex UART Serial Channel• Low-power Idle and Power-down Modes• Interrupt Recovery from Power-down Mode• Watchdog Timer• Dual Data Pointer• Power-off FlagPin DescriptionVCCSupply voltage.GNDGround.Port 0Port 0 is an 8-bit open drain bidirectional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs.Port 0 can 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 pullups.Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pullups are required during program verification.Port 1Port 1 is an 8-bit bidirectional I/O port with internal pullups. The Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the internal pullups 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.In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX), respectively.Port 1 also receives the low-order address bytes during Flash programming and verification.Port 2Port 2 is an 8-bit bidirectional I/O port with internal pullups. 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 pullups 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 pullups.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, Port 2 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 during Flash programming and verification.Port 3Port 3 is an 8-bit bidirectional I/O port with internal pullups. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the internal pullups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pullups.Port 3 also serves the functions of various special features of the AT89S52, as shown in the following table.Port 3 also receives some control signals for Flash programming and verification.RSTReset input. A high on this pin for two machine cycles while the oscillator is running resets the device. This pin drives High for 96 oscillator periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled.ALE/PROGAddress Latch Enable (ALE) is an 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 during 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.PSENProgram Store Enable (PSEN) is the read strobe to external program memory. When the AT89S52 is executing code from external program memory, PSENis activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.EA/VPPExternal 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 also receives the 12-volt programming enable voltage (VPP) during Flash programming.XTAL1Input to the inverting oscillator amplifier and input to the internal clock operating circuit.XTAL2Output from the inverting oscillator amplifier.Special Function RegistersNote that not all of the addresses are occupied, and unoccupied addresses may not be implemented on the chip. Read accesses to these addresses will in general return random data, and write accesses will have an indeterminate effect.User software should not write 1s to these unlisted locations, since they may be used in future products to invoke new features. In that case, the reset or inactive values of the new bits will always be 0.Timer 2 Registers:Control and status bits are contained in registers T2CON and T2MOD for Timer 2. The register pair (RCAP2H, RCAP2L) are the Capture/Reload registers for Timer 2 in 16-bit capture mode or 16-bit auto-reload mode.Interrupt Registers:The individual interrupt enable bits are in the IE register. Two priorities can be set for each of the six interrupt sources in the IP register.Dual Data Pointer Registers: To facilitate accessing both internal and external data memory, two banks of 16-bit Data Pointer Registers areprovided: DP0 at SFR address locations 82H-83H and DP1 at 84H-85H. Bit DPS = 0 in SFR AUXR1 selects DP0 and DPS = 1 selects DP1. The user should always initialize the DPS bit to the appropriate value before accessing the respective Data Pointer Register.Power Off Flag:The Power Off Flag (POF) is located at bit 4 (PCON.4) in the PCON SFR. POF is set to “1” during power up. It can be set and rest under software control and is not affected by reset.Memory OrganizationMCS-51 devices have a separate address space for Program and Data Memory. Up to 64K bytes each of external Program and Data Memory can be addressed.Program MemoryIf the EA pin is connected to GND, all program fetches are directed to external memory. On the AT89S52, if EA is connected to VCC, program fetches to addresses 0000H through 1FFFH are directed to internal memory and fetches to addresses 2000H through FFFFH are to external memory.Data MemoryThe AT89S52 implements 256 bytes of on-chip RAM. The upper 128 bytes occupy a parallel address space to the Special Function Registers. This means that the upper 128 bytes have the same addresses as the SFR space but are physically separate from SFR space.When an instruction accesses an internal location above address 7FH, the address mode used in the instruction specifies whether the CPU accesses the upper 128 bytes of RAM or the SFR space. Instructions which use direct addressing access of the SFR space. For example, the following direct addressing instruction accesses the SFR at location 0A0H (which is P2).MOV 0A0H, #dataInstructions that use indirect addressing access the upper 128 bytes of RAM. For example, the following indirect addressing instruction, where R0 contains 0A0H, accesses the data byte at address 0A0H, rather than P2 (whose address is 0A0H).MOV @R0, #dataNote that stack operations are examples of indirect addressing, so the upper 128 bytes of data RAM are available as stack space.Timer 0 and 1Timer 0 and Timer 1 in the AT89S52 operate the same way as Timer 0 and Timer 1 in the AT89C51 and AT89C52.Timer 2Timer 2 is a 16-bit Timer/Counter that can operate as either a timer or an event counter. The type of operation is selected by bit C/T2 in the SFR T2CON (shown in Table 2). Timer 2 has three operating modes: capture, auto-reload (up or down counting), and baud rate generator. The modes are selected by bits in T2CON.Timer 2 consists of two 8-bit registers, TH2 and TL2. In the Timer function, the TL2 register is incremented every machine cycle. Since a machine cycle consists of 12 oscillator periods, the count rate is 1/12 of the oscillator frequency.In the Counter function, the register is incremented in response to a1-to-0 transition at its corresponding external input pin, T2. In this function, the external input is sampled during S5P2 of every machine cycle. When the samples show a high in one cycle and a low in the next cycle, the count is incremented. The new count value appears in the register during S3P1 of the cycle following the one in which the transition was detected. Since two machine cycles (24 oscillator periods) are required to recognize a 1-to-0 transition, the maximum count rate is 1/24 of the oscillator frequency. To ensure that a given level is sampled at least once before it changes, the level should be held for at least one full machine cycle.InterruptsThe AT89S52 has a total of six interrupt vectors: two external interrupts (INT0 and INT1), three timer interrupts (Timers 0, 1, and 2), and the serial port interrupt. These interrupts are all shown in Figure 10.Each of these interrupt sources can be individually enabled or disabledby setting or clearing a bit in Special Function Register IE. IE also contains a global disable bit, EA, which disables all interrupts at once.Note that Table 5 shows that bit position IE.6 is unimplemented. In the AT89S52, bit position IE.5 is also unimplemented. User software should not write 1s to these bit positions, since they may be used in future AT89 products. Timer 2 interrupt is generated by the logical OR of bits TF2 and EXF2 in register T2CON. Neither of these flags is cleared by hardware when the service routine is vectored to. In fact, the service routine may have to determine whether it was TF2 or EXF2 that generated the interrupt, and that bit will have to be cleared in software.The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the cycle in which the timers overflow. The values are then polled by the circuitry in the next cycle. However, the Timer 2 flag, TF2, is set at S2P2 and is polled in the same cycle in which the timer overflows.二、译文单片机单片机即微型计算机，是把中央处理器、存储器、定时/计数器、输入输出接口都集成在一块集成电路芯片上的微型计算机。
(完整版)_毕业设计英文翻译_及格式
毕业设计(论文)英文翻译题目专业班级姓名学号指导教师职称200年月日The Restructuring of OrganizationsThroughout the 1990s, mergers and acquisitions a major source of corporate restructuring, affecting millions of workers and their families. This form of restructuring often is accompanied by downsizing. Downsizing is the process of reducing the size of a firm by laying off or retiring workers early. The primary objectives of downsizing are similar in U.S. companies and those in other countries:●cutting cost,●spurring decentralization and speeding up decision making,●cutting bureaucracy and eliminating layers of especially they did five years ago. One consequence of this trend is that today’s managers supervise larger numbers of subordinates who report directly to them. In 1990, only about 20 percent of managers supervise twelve or more people and 54 percent supervised six or fewer.Because of downsizing, first-line managers quality control, resources, and industrial engineering provide guidance and support. First-line managers participate in the production processes and other line activities and coordinate the efforts of the specialists as part of their jobs. At the same time, the workers that first-line managers supervise are less willing to put up with authoritarian management. Employees want their jobs to be more creative, challenging, fun, and satisfying and want to participate in decisions affecting their work. Thus self-managed work teams that bring workers and first-line managers together to make joint decisions to improve the way they do their jobs offer a solution to both supervision and employee expectation problems. When you ’t always the case. Sometimes entire divisions of a firm are simply spun off from the main company to operate on their own as new, autonomous companies. The firm that spun them off may then become one of their most important customers or suppliers. That AT&T “downsized” the old Bell Labs unit, which is now known as Lucent Technologies. Now, rather than - return is free to enter into contracts with companies other than AT&T. this method of downsizing is usually called outsourcing.Outsourcing means letting other organizations perform a needed service andor manufacture needed parts or products. Nike outsources the production of its shoes to low-cost plants in South Korea and China and imports the shoes for distribution in North America. These same plants also ship shoes to Europe and other parts of Asia for distribution. Thus today’s managers face a new challenge: t o plan, organize, lead, and control a company that may as a modular corporation. The modularcorporation is most is most common in three industries: apparel, auto manufacturing, and electronics. The most commonly out-sourced function is production. By out sourcing production, a company can switch supplier best suited to a customer’s needs.Decisions about what to outsource and what to keep in- to contract production to another company is a sound business decision to contract production to another company is a sound business decision, at least for U.S. manufacturers. It appears to the unit cost of production by relieving the company of some overhead, and it frees the company to allocate scarce resources to activities for which the company examples of modular companies are Dell Computer, Nike, Liz Claiborne fashions, and ship designer Cyrix.As organizations downsize and outsource functions, they become flatter and smaller. Unlike the behemoths of the past, the new, smaller firms are less like autonomous fortresses and more like nodes in a net work of complex relationships. This approach, called the network form of organization, involves establishing strategic alliances among several entities.In Japan, cross-ownership and alliances among firms－called keiretsu－both foreign and U.S. auto parts producers. It also owns 49 percent of Hertz, the car rental company that is also a major customer. Other alliances include involvement in several research consortia. In the airline industry, a common type of alliance is between an airline and an airframe manufacture. For example, Delta recently agreed to buy all its aircraft from Boeing. Boeing Airlines. Through these agreements, Boeing guarantees that it will be able to sell specified models of its aircraft and begin to adapt their operations to the models they will be flying in the future. Thus both sides expect to reap benefits from these arrangements for many years.Networks forms of organizations are prevalent in access to the universities and in small, creative organizations. For example, the U.S. biotechnology industry is characterized by network of relationships between new biotechnology firms dedicated to research and new products development and established firms in industries that can use these new products, such as pharmaceuticals. In return for sharing technical information with the larger firms, the smaller firms gain access to their partners’ resources for product testing, marketing, and distribution. Big pharmaceutical firms such as Merk or Eli Lily gain from such partnerships because the smaller firms typically development cycle in the larger firms.Being competitive increasingly requires establishing and managing strategic alliances with other firms. In a strategic alliance, two or more firms agree to cooperate in a venture that is expected to benefit both firms.企业重组整个20世纪90年代中，合并和收购一直是企业重组的主要起源，影响着千百万的工人和他们的家庭。
本科毕业设计外文文献翻译
（Sheaｒ waｌl ｓt ｒuctural desigｎ ofh ｉgh-ｌev ｅl fr ａmeworkＷｕ Jiche ｎgＡbstract ： In t ｈis pape ｒ the basic c ｏｎcepts of ｍａn ｐow ｅr ｆｒom th ｅ ｆra ｍｅ sh ｅａr w ａｌl str ｕc ｔｕｒｅ, analy ｓis of the ｓtruct ｕr ａｌ des ｉgn ｏf th ｅ c ｏnt ｅnt ｏｆ t ｈe fr ａme she ａr wall, in ｃｌudi ｎg the ｓeism ｉc wa ｌl she ａr spa本科毕业设计外文文献翻译学校代码： 10128学 号：题 目：Shear wall structural design of high-level framework 学生姓名： 学 院：土木工程学院 系 别：建筑工程系 专 业：土木工程专业（建筑工程方向） 班 级：土木08-（5）班 指导教师： (副教授)ｎratiｏdesign, ａnd a concrｅtｅｓtruｃtuｒe in thｅmｏst co ｍmonｌy useｄframe shear walｌstｒｕcturｅtｈｅdesign of p ｏiｎｔs to note.Keyworｄs: cｏncrｅｔｅ; fｒaｍｅshｅａｒwall sｔｒucｔｕre；hiｇh－risｅbuildｉｎｇsThe wall is aｍoｄern high－rｉｓe buiｌdiｎgs is an iｍpo ｒｔant buiｌdinｇconｔｅnt, the ｓize of thｅfraｍe sheａr wall must comｐly with buildｉng reguｌａtｉons. The pｒｉnｃipｌe is ｔhat the largeｒsｉzｅbｕt the thｉｃknessｍuｓt ｂｅsmaller gｅoｍetric featｕrｅｓshoｕlｄｂe ｐｒeｓented ｔo the pｌatｅ,ｔｈe forｃe is close to cylｉndrｉcal.Ｔhe waｌl sｈｅar wa ｌl strｕｃｔure ｉs a flaｔcomｐonent. Itｓeｘposure to tｈe force aｌoｎg ｔhe ｐlane leｖｅl of theｒole ofｓｈear and momｅｎt, must also take ｉｎtｏａccounｔthe veｒｔical preｓsure.Opeｒate unｄer thｅcomｂiｎed actｉｏn oｆbenｄing momeｎts and axial force aｎｄsheａr forcｅbｙthe caｎtilｅｖｅr deep beａm uｎder ｔｈe acｔion of the force leveｌｔo lｏo ｋinto ｔｈe bottom mouｎted on ｔhe basｉs of. Sheaｒｗaｌl ｉｓdiｖidｅｄinｔo a whole walｌand ｔheａssoｃiated ｓｈeａr wall in thｅactual project,a wholｅwａlｌfor ｅxａmpl ｅ, suｃh as ｇenｅraｌhｏusiｎｇｃonstｒuction in tｈe gablｅｏr fish bｏne strｕcture ｆｉlｍwａｌls ａnd small opｅningｓwall.Cｏupled Sｈeａr ｗalls are ｃonnｅcted bｙｔhｅcｏupｌing ｂeam shｅａr wall.Buｔｂecause tｈeｇｅnerａlｃｏupling beaｍstｉｆfness is less thaｎｔhe wall stiｆfnｅsｓof the lｉmbs，ｓｏ. Wａlｌliｍb aｌonｅis obviｏus.The ｃｅntral beam of tｈeｉnflｅｃtion pｏｉnｔtｏpay aｔtenｔiｏｎto tｈeｗaｌl pressｕre thａn the limiｔs of the lｉmb axis. Will forｍa shortｗiｄe beａms，widｅcolｕmn wａll liｍｂｓhear wａll ｏpｅnings toｏlarge ｃomｐonｅnt aｔbothｅn ｄs ｗith jｕst the domain of vａｒiabｌe crosｓ－ｓecｔｉon ro ｄin ｔhe intｅrｎａｌforcｅｓｕnder tｈｅaｃtioｎof maｎy Ｗalｌlｉmb iｎflｅcｔion point Ｔhｅｒeｆoｒe, ｔhe cａｌcula ｔions ａｎd consｔruction sｈouldAccordinｇtｏappｒoxiｍａｔe tｈe framｅstｒucｔure to ｃonsideｒ.Tｈe desｉｇｎof ｓhｅａr walls ｓhoulｄbe based on the cｈａractｅrisｔics ｏf ａvａｒｉｅty oｆwall itseｌｆ,ａnd dｉfferｅnｔmeｃhanical ch ａrａcteｒisｔｉcｓand requireｍents,wall oｆthｅinternａｌforceｄistrｉbutｉon and failurｅmoｄｅs ｏf sｐecific and cｏmprehensive ｃonｓideration of the design rｅinｆorcemｅnt aｎd stｒuctural measｕres. Ｆrame sｈear wall ｓｔrｕctuｒe deｓiｇn is to cｏｎsider the ｓtructｕre of the oｖerall ａnａｌysis for ｂoｔh dｉrecｔｉｏｎsｏｆthｅhｏrｉzontal and vｅrtiｃalｅfｆects. Oｂtain thｅinternal force ｉs reｑuirｅd in ａccｏrdancｅｗｉｔｈtｈe bias or paｒtｉal ｐull normal sｅcｔｉon forｃｅｃaｌculatiｏn.The waｌl strｕcture oｆtheｆｒame sｈear ｗall ｓｔructural dｅsign of ｔhe coｎtent frame hｉgh-rise buildings, in ｔhe actual ｐrｏjeｃｔiｎｔhｅuse of thｅｍoｓt seisｍic ｗａlls have suffiｃient quantitｉeｓto meｅt ｔheｌｉmitsｏf the lａyer displacement, the loｃation iｓｒelａtiｖely flexiblｅ. Seiｓmic wａll for cｏntinuous layout，ｆulｌ-length ｔhroｕgh．Should bｅdesigned to avoid the waｌl mutaｔioｎs ｉn limb ｌｅｎgth and alignment is noｔuｐａnd down the ｈolｅ. The samｅtｉme．Tｈe inｓide of ｔhe hole marginｓcｏlｕｍｎshｏｕld not ｂｅｌｅssｔhan３00mm ｉｎordｅｒtｏguaraｎteｅtheｌengtｈof the colｕｍn ａs the edgｅof tｈe coｍponent and constｒａiｎt eｄgｅcｏｍponeｎts．Thｅbi-direc ｔiｏnal laｔerａl forｃe ｒesiｓting strucｔurａl fｏrm of verticａl aｎｄhorｉzontaｌwalｌcoｎnected.Eａｃh ｏｔhｅr as ｔhe ａffiｎiｔｙof the shｅar wall. Ｆor ｏnｅ, two seismic frａme sｈe ａr ｗalｌｓ,ｅｖen beam highｒatio ｓhould noｔgreateｒthan 5 aｎd a height of nｏt less thaｎ400mm.Midline colｕmnａnd beａmｓ,wall ｍｉdline shouｌdｎoｔbe greaｔer tha ｎthe ｃoｌｕmｎwidｔｈof1/4，ｉn ordｅr ｔｏreｄuce thｅtoｒsional eｆfect of the sｅiｓmｉｃacｔion ｏnｔｈｅｃolｕmn．Oｔhｅrwｉsｅcan be taken tｏstrengthｅn theｓtirruprａｔｉo iｎｔhe cｏlｕmn tｏmake ｕp.If thｅshear wａｌl sheａｒsｐａn ｔhａnｔhe ｂig twｏ. Ｅveｎthe beａｍcro ｓs-heｉｇht ratiｏgreateｒthan 2.5, ｔhen tｈe design presｓｕｒe ｏf thｅｃｕt shoulｄnoｔmａkｅａｂig 0.2. Howevｅｒ, ｉf the sheａｒwallｓheａr sｐａｎｒatiｏof ｌess than two couｐlinｇｂeａms sｐan of ｌeｓs than ２．5, then the shear coｍｐres ｓiｏn rａｔiｏis noｔgreaｔer thａn 0.15. Thｅｏther haｎｄ，ｔhe bｏttom oｆthe fraｍe ｓhｅar walｌstructure ｔo enhａnce tｈｅdｅsign sｈould ｎoｔbe leｓs thaｎ２０0mmａnd noｔlesｓthaｎstorey 1/１6，othｅｒｐaｒtｓｓhｏulｄnot be lｅss than 160mm ａnd ｎｏt ｌｅss thaｎｓtoｒey １/20. Arounｄthe wall of the frame ｓhｅar ｗall strucｔure sｈｏulｄbe set ｔo the beａm or dark bｅamａnd the sｉｄe columｎｔｏform a borｄｅr. Ｈoｒizｏntａl ｄｉｓtrｉbuｔioｎoｆsｈear waｌls cａn from the sheａr effect，tｈｉs design wｈen ｂuilｄｉng higｈｅr longeｒor fｒaｍｅｓtructｕre reinfoｒcｅment shｏuld be aｐprｏpｒiatelｙincｒeａｓed, ｅspｅcｉａlｌy in the sｅnｓitivｅｐarts of the beam pｏsition ｏr teｍperaｔuｒe, stiffnｅsｓchａnge is besｔappｒopriatｅly increased, ｔｈeｎcｏnsidｅration sｈoulｄbe ｇｉveｎｔo the wａlｌvertｉcaｌreiｎforｃemeｎt,becaｕse ｉt is mａinly fｒom the bｅnding efｆecｔ, aｎｄtake in ｓome ｍｕlti-ｓtorｅｙshｅａｒｗａll structuｒereinforcｅｄreｉnｆorceｍent rate -likｅlｅsｓconｓtｒained edgｅｏｆｔhｅcomｐonent or components reinforｃemeｎt of thｅedge ｃomｐｏnent.Referｅnces: [1 sad Hａyaｓhi,He Yaming. Ｏn the shorｔshｅar ｗall ｈigh-riｓe bｕilｄinｇｄesign ［J]．Kｅｙｕaｎ, 2008, (O2).高层框架剪力墙结构设计吴继成摘要: 本文从框架剪力墙结构设计的基本概念人手, 分析了框架剪力墙的构造设计内容, 包括抗震墙、剪跨比等的设计, 并出混凝土结构中最常用的框架剪力墙结构设计的注意要点。
毕业设计外文资料翻译sc-pdf
毕业设计外文资料翻译题目甲醇氧化生产甲醛的银催化剂改性学院化学化工学院专业化学工程与工艺班级0803学生许继盟学号20080207167指导教师倪献智二〇一二年三月十五日Catalysts Today, 1996, (28): 239-244.甲醇氧化生产甲醛的银催化剂的改性A.N.Pestryakov摘 要 银催化剂的性能可用Zr ，La ， Rb ，C s 的氧化物改性，改性后的银催化剂的物化性能和催化性能已在甲醇的选择性氧化工艺中研究过，甲醇氧化制甲醛工艺中，质量分数为1%-10%的改性添加物会改变载体银的有效电荷及氧化还原性能、金属分散度和其表面扩散、催化剂表面酸度及结焦程度。
当银催化性能改变时，改性物主要影响催化剂活性位（++δn Ag Ag）。
关键词 银催化剂；甲醇氧化为甲醛 1 简介甲醇选择性氧化生产甲醛工艺中使用大量的载体银催化剂[1-3]。
采用不同的非有机添加物对银催化剂进行改性是提高其性能的最有前景的方法之一。
在银催化剂发现之后，人们致力于对其进行改进，以达到提高其催化活性和寿命，降低银使用量和扩展其工艺操作条件的目的。
广泛使用载体以减少银使用量及防止银在“严酷”条件（600-700 ℃）下烧结也是改性方法之一。
但是载体的堆积有限，不同改性化合物的少量添加（质量分数0.1-10%）可以使银可变的催化性能产生较大差异。
在科技和专利文献中提到过很多不同的添加物，它们能改善并激发银的催化性能[3-14]。
在这其中，研究人员提到改性作用的不同机理：银上金属的电子功能和电子密度改变[7-9]，O 2吸附的差异[3,10]，催化剂表面酸度[11]，催化剂表面的机械堵塞[12]，添加物的固有催化性质[13,14]。
然而，所有这些仅描述了催化剂改性的几个分散的方面，并没有涉及添加物对银催化剂改性影响的差异。
也没有考虑改性物对银催化剂活性位电子状态的影响。
在本文中，我们研究了改性物对银的性能影响的几个方面[15-18]，目的是在甲醇氧化制甲醛工艺中对稀有和稀土金属氧化物反应及银催化剂的电子属性、物化属性和催化属性进行综合研究。
毕业设计(论文)外文资料翻译【范本模板】
南京理工大学紫金学院毕业设计（论文）外文资料翻译系：机械系专业：车辆工程专业姓名:宋磊春学号:070102234外文出处：EDU_E_CAT_VBA_FF_V5R9(用外文写)附件：1。
外文资料翻译译文；2.外文原文.附件1：外文资料翻译译文CATIA V5 的自动化CATIA V5的自动化和脚本：在NT 和Unix上：脚本允许你用宏指令以非常简单的方式计划CATIA。
CATIA 使用在MS –VBScript中(V5.x中在NT和UNIX3。
0 )的共用部分来使得在两个平台上运行相同的宏。
在NT 平台上：自动化允许CATIA像Word/Excel或者Visual Basic程序那样与其他外用分享目标。
ATIA 能使用Word/Excel对象就像Word/Excel能使用CATIA 对象。
在Unix 平台上:CATIA将来的版本将允许从Java分享它的对象。
这将提供在Unix 和NT 之间的一个完美兼容。
CATIA V5 自动化：介绍（仅限NT）自动化允许在几个进程之间的联系:CATIA V5 在NT 上：接口COM：Visual Basic 脚本(对宏来说)，Visual Basic 为应用（适合前:Word/Excel )，Visual Basic。
COM（零部件目标模型)是“微软“标准于几个应用程序之间的共享对象。
Automation 是一种“微软“技术,它使用一种解释环境中的COM对象。
ActiveX 组成部分是“微软“标准于几个应用程序之间的共享对象,即使在解释环境里。
OLE（对象的链接与嵌入）意思是资料可以在一个其他应用OLE的资料里连结并且可以被编辑的方法(在适当的位置编辑）.在VBScript,VBA和Visual Basic之间的差别：Visual Basic(VB）是全部的版本。
它能产生独立的计划,它也能建立ActiveX 和服务器。
它可以被编辑。
VB中提供了一个补充文件名为“在线丛书“(VB的5。
毕业设计外文翻译
毕业设计外文翻译Newly compiled on November 23, 2020Title:ADDRESSING PROCESS PLANNING AND VERIFICATION ISSUES WITH MTCONNECTAuthor:Vijayaraghavan, Athulan, UC BerkeleyDornfeld, David, UC BerkeleyPublication Date:06-01-2009Series:Precision Manufacturing GroupPermalink:Keywords:Process planning verification, machine tool interoperability, MTConnect Abstract:Robust interoperability methods are needed in manufacturing systems to implement computeraided process planning algorithms and to verify their effectiveness. In this paper wediscuss applying MTConnect, an open-source standard for data exchange in manufacturingsystems, in addressing two specific issues in process planning and verification. We use data froman MTConnect-compliant machine tool to estimate the cycle time required for machining complexparts in that machine. MTConnect data is also used in verifying the conformance of toolpaths tothe required part features by comparing the features created by the actual tool positions to therequired part features using CAD tools. We demonstrate the capabilities of MTConnect in easilyenabling process planning and verification in an industrial environment.Copyright Information:All rights reserved unless otherwise indicated. Contact the author or original publisher for anynecessary permissions. eScholarship is not the copyright owner for deposited works. Learn moreADDRESSING PROCESS PLANNING AND VERIFICATION ISSUESWITH MTCONNECTAthulan Vijayaraghavan, Lucie Huet, and David DornfeldDepartment of Mechanical EngineeringUniversity of CaliforniaBerkeley, CA 94720-1740William SobelArtisanal SoftwareOakland, CA 94611Bill Blomquist and Mark ConleyRemmele Engineering Inc.Big Lake, MNKEYWORDSProcess planning verification, machine tool interoperability, MTConnect.ABSTRACTRobust interoperability methods are needed in manufacturing systems to implement computeraided process planning algorithms and to verifytheir effectiveness. In this paper we discuss applying MTConnect, an open-source standardfor data exchange in manufacturing systems, in addressing two specific issues in processplanning and verification. We use data from an MTConnect-compliant machine tool to estimatethe cycle time required for machining complex parts in that machine. MTConnect data is also used in verifying the conformance of toolpaths to the required part features by comparing the features created by the actual tool positions tothe required part features using CAD tools. We demonstrate the capabilities of MTConnect in easily enabling process planning and verificationin an industrial environment.INTRODUCTIONAutomated process planning methods are acritical component in the design and planning of manufacturing processes for complex parts. Thisis especially the case with high speed machining, as the complex interactions betweenthe tool and the workpiece necessitates careful selection of the process parameters and the toolpath design. However, to improve the effectiveness of these methods, they need to be integrated tightly with machines and systems in industrial environments. To enable this, we need robust interoperability standards for data exchange between the different entities in manufacturing systems.In this paper, we discuss using MTConnect – an open source standard for data exchange in manufacturing systems – to address issues in process planning and verification in machining.We discuss two examples of using MTConnect for better process planning: in estimating the cycle time for high speed machining, and in verifying the effectiveness of toolpath planning for machining complex features. As MTConnect standardizes the exchange of manufacturing process data, process planning applications can be developed independent of the specific equipment used (Vijayaraghavan, 2008). This allowed us to develop the process planning applications and implement them in an industrial setting with minimal overhead. The experiments discussed in this paper were developed at UC Berkeley and implemented at Remmele Engineering Inc.The next section presents a brief introduction to MTConnect, highlighting its applicability in manufacturing process monitoring. We then discuss two applications of MTConnect – in computing cycle time estimates and in verifying toolpath planning effectiveness. MTCONNECTMTConnect is an open software standard for data exchange and communication between manufacturing equipment (MTConnect, 2008a). The MTConnect protocol defines a common language and structure for communication in manufacturing equipment, and enables interoperability by allowing access to manufacturing data using standardized interfaces. MTConnect does not define methods for data transmission or use, and is not intended to replace the functionality of existing products and/or data standards. It enhances the data acquisition capabiltiies of devices and applications, moving towards a plug-and-play environment that can reduce the cost of integration. MTConnect is built upon prevalent standards in the manufacturing and software industry, which maximizes the number of tools available for its implementation and provides a high level of interoperability with other standards and tools in these industries.MTConnect is an XML-based standard andmessages are encoded using XML (eXtensibleMarkup Language), which has been usedextensively as a portable way of specifying data interchange formats (W3C, 2008). A machinereadable XML schema defines the format ofMTConnect messages and how the data itemswithin those messages are represented. At thetime of publication, the latest version of the MTConnect standard defining the schema is (MTConnect, 2008b).The MTConnect protocol includes the following information about a device:Identity of a deviceIdentity of all the independent components ofthe deviceDesign characteristics of the deviceData occurring in real or near real-time by thedevice that can be utilized by other devices or applications. The types of data that can beaddressed includes:Physical and actual device design dataMeasurement or calibration dataNear-real time data from the deviceFigure 1 shows an example of a data gatheringsetup using MTConnect. Data is gathered innear-time from a machine tool and from thermal sensors attached to it. The data stored by the MTConnect protocol for this setup is shown inTable 1. Specialized adaptors are used to parsethe data from the machine tool and from thesensor devices into a format that can beunderstood by the MTConnect agent, which inturn organizes the data into the MTConnect XML schema. Software tools can be developed which operate on the XML data from the agent. Sincethe XML schema is standardized, the softwaretools can be blind to the specific configuration ofthe equipment from where the data is gathered. FIGURE 1: MTCONNECT SETUP.TABLE 1:MTCONNECT PROTOCOL INFORMATION FOR MACHINE TOOL IN FIGURE 1.Device identity “3-Axis Milling Machine”Devicecomponents1 X Axis; 1 Y Axis; 1 Z Axis;2 Thermal SensorsDevice designcharacteristicsX Axis Travel: 6”Y Axis Travel: 6”Z Axis Travel: 12”Max Spindle RPM: 24000Data occurringin deviceTool position: (0,0,0);Spindle RPM: 1000Alarm Status: OFFTemp Sensor 1: 90oFTemp Sensor 2: 120oFAn added benefit of XML is that it is a hierarchical representation, and this is exploited by designing the hierarchy of the MTConnect schema to resemble that of a conventional machine tool. The schema itself functions as a metaphor for the machine tool and makes the parsing and encoding of messages intuitive. Data items are grouped based on their logical organization, and not on their physical organization. For example, Figure 2 shows the XML schema associated with the setup shown in Figure 1. Although the temperature sensors operate independant of the machine tool (with its own adaptor), the data from the sensors are associated with specific components of the machine tool, and hence the temperature data is a member of the hierarchy of the machine tool. The next section discusses applying MTConnect in estimating cycle time in high-speed machining.ACCURATE CYCLE TIME ESTIMATESIn high speed machining processes there can be discrepancies between the actual feedrates during cutting and the required (or commanded) feedrates. These discrepancies are dependenton the design of the controller used in the machine tool and the toolpath geometry. While there have been innovative controller designs that minimize the feedrate discrepancy (Sencer,2008), most machine tools used in conventional industrial facilities have commercial off-the-shelf controllers that demonstrate some discrepancies in the feedrates, especially when machining complex geometries at high speeds. There is a need for simple tools to estimate the discrepancy in these machining conditions. Apart from influencing the surface quality of the machined parts, feedrate variation can lead to inaccurate estimates of the cycle time during machining. Accurate estimates of the cycle time is a critical requirement in planning for complex machining operations in manufacturing facilities. The cycle time is needed for both scheduling the part in a job shop, as well as for costing the part. Inaccurate cycle time estimates (especiallywhen the feed is overestimated) can lead to uncompetitive estimates for the cost of the part and unrealistic estimates for the cycle time. Related Workde Souza and Coelho (2007) presented a comprehensive set of experiments to demonstrate feedrate limitations during the machining of freeform surfaces. They identified the causes of feedrate variation as dynamic limitations of the machine, block processing time FIGURE 2: MTCONNECT HIERARCHY.for the CNC, and the feature size in the toolpaths. Significant discrepancies were observed between the actual and commanded feeds when machining with linear interpolation (G01). The authors used a custom monitoring and data logging system to capture the feedrate variation in the CNC controller during machining. Sencer et al. (2008) presented feed scheduling algorithms to minimize the machining time for 5- axis contour machining of sculptured surfaces. The algorithm optimized the profile of the feedrate for minimum machining time, while observing constrains on the smoothness of the feedrate, acceleration and jerk of the machine tool drives. This follows earlier work in minimizing the machining time in 3-axis milling using similar feed scheduling techniques(Altintas, 2003). While these methods are very effective in improving the cycle time of complex machining operations, they can be difficult toapply in conventional factory environments asthey require specialized control systems. The methods we discuss in this paper do notaddress the optimization of cycle time during machining. Instead, we provide simple tools to estimate the discrepancy in feedrates during machining and use this in estimating the cycletime for arbitrary parts.MethodologyDuring G01 linear interpolation the chief determinant of the maximum feedrateachievable is the spacing between adjacentpoints (G01 step size). We focus on G01 interpolation as this is used extensively when machining simultaneously in 3 or more axes.The cycle time for this machine tool to machinean arbitrary part (using linear interpolation) is estimated based on the maximum feedachievable by the machine tool at a given path spacing. MTConnect is a key enabler in this process as it standardizes both data collectionas well as the analysis.The maximum feedrate achievable is estimated using a standardized test G-code program. This program consists of machining a simple shapewith progressively varying G01 path spacings.The program is executed on an MTConnectcompliant machine tool, and the position andfeed data from the machine tool is logged innear-real time. The feedrate during cutting at the different spacings is then analyzed, and amachine tool “calibration” curve is developed, which identifies the maximum feedrate possibleat a given path spacing.FIGURE 3: METHODOLOGY FOR ESTIMATING CYCLE TIME.Conventionally, the cycle time for a giventoolpath is estimated by summing the time takenfor the machine tool to process each block of Gcode, which is calculated as the distancetravelled in that block divided by the feedrate ofthe block. For a given arbitrary part G-code to be executed on a machine tool, the cycle time is estimated using the calibration curve as follows. For each G01 block executed in the program, the size of the step is calculated (this is the distance between the points the machine tool is interpolating) and the maximum feedrate possible at this step size is looked up from the calibration curve. If the maximum feedrate is smaller than the commanded feedrate, this line of the G-code is modified to machine at the (lower) actual feedrate, if the maximum feedrate is greater, then the line is left unmodified. This is performed for all G01 lines in the program, and finally, the cycle time of the modified G-code program is estimated the conventional way. This methodology is shown in Figure 3. The next section discusses an example applying this methodology on a machine tool.ResultsWe implemented the cycle time estimation method on a 3-axis machine tool with a conventional controller. The calibration curve of this machine tool was computed by machining a simple circular feature at the following linear spacings: ”, ”, ”, ”,”, ”, ”, ”, ”. Weconfirmed that the radius of the circle (that is, the curvature in the toolpath) had no effect on the feedrate achieved by testing with circular features of radius ”, ”, and ”, andobserving the same maximum feedrate in all cases. Table 2 shows the maximum achievable feedrate at each path spacing when using a circle of radius 1”. We can see from the table that the maximum feedrate achievable is a linear function of the path spacing. Using a linear fit, the calibration curve for this machine tool can be estimated. Figure 4 plots the calibration curve for this machine tool. The relationship between the feedrate and the path spacing is linear asthe block processing time of the machine tool controller is constant at all feedrates. The block processing time determines the maximumfederate achievable for a given spacing as it isthe time the machine tool takes to interpolateone block of G-code. As the path spacing (or interpolatory distance) linearly increases, thespeed at which it can be interpolated alsoincreases linearly. The relationship for the datain Figure 4 is:MAX FEED (in/min) = 14847 * SPACING (in)TABLE 2: MAXIMUM ACHIEVABLE FEEDRATE AT VARYING PATH SPACINGSpacing Maximum Feedrate”””””””””We also noticed that the maximum feedrate for agiven spacing was unaffected by thecommanded feedrate, as long as it was lesserthan the commanded feedrate. This means thatit was adequate to compute the calibration curveby commanding the maximum possible feedratein the machine tool.FIGURE 4: CALIBRATION CURVE FOR MACHINE TOOL.Using this calibration curve, we estimated thecycle time for machining an arbitrary feature inthis machine tool. The feature we used was a3D spiral with a smoothly varying path spacing,which is shown in Figure 5. The spiral path isdescribed exclusively using G01 steps andinvolves simultaneous 3-axis interpolation. Thepath spacing of the G-code blocks for thefeature is shown in Figure 6.FIGURE 5: 3D SPIRAL FEATURE.FIGURE 6: PATH SPACING VARIATION WITH GCODE LINE FOR SPIRAL FEATURE.Figure 7 shows the predicted feedrate based onthe calibration curve for machining the spiralshape at 100 inches/min, compared to the actualfeedrate during machining. We can see that the feedrate predicted by the calibration curvematches very closely with the actual feedrate.We can also observe the linear relationship between path spacing and maximum feedrate by comparing figures 6 and 7.FIGURE 7: PREDICTED FEEDRATE COMPARED TO MEASURED FEEDRATE FOR SPIRAL FEATURE AT 100 IN/MIN.FIGURE 8: ACTUAL CYCLE TIME TO MACHINE SPIRAL FEATURE AT DIFFERENT FEEDRATES. The cycle time for machining the spiral atdifferent commanded feedrates was alsoestimated using the calibration curve. Figure 8 shows the actual cycle time taken to machinethe spiral feature at different feedrates. Noticehere that the trend is non-linear – an increase infeed does not yield a proportional decrease incycle time – implying that there is somefeedrate discrepancy at high feeds. Figure 9 compares the theoretical cycle time to machineat different feedrates to the actual cycle time andthe model predicted cycle time. We can see thatthe model predictions match the cycle times very closely (within 1%). Significant discrepancies are seen between the theoretical cycle time and the actual cycle time when machining at high feed rates. These discrepancies can be explained bythe difference between the block processingtime for the controller, and the time spent oneach block of G-Code during machining. At high feedrates, the time spent at each block is shorterthan the block processing time, so the controller slows down the interpolation resulting in a discrepancy in the cycle time.These results demonstrated the effectiveness of using the calibration curve to estimate feed, and ultimately apply in estimating the cycle time.This method can be extrapolated to multi-axis machining by measuring the feedrate variationfor linear interpolation in specific axes. We canalso specifically correlate feed in one axis to the path spacing instead of the overall feedrate. FIGURE 9: ACTUAL OBSERVED CYCLE TIMESAND PREDICTED CYCLE TIMES COMPARED TO THE NORMALIZED THEORETICAL CYCLE TIMES FOR MACHINING SPIRAL FEATURE AT DIFFERENT FEEDRATES.TOOL POSITION VERIFICATIONMTConnect data can also be used in verifying toolpath planning for the machining of complex parts. Toolpaths for machining complex featuresare usually designed using specialized CAM algorithms, and traditionally the effectiveness ofthe toolpaths in creating the required partfeatures are either verified using computer simulations of the toolpath, or by surfacemetrology of the machined part. The formerapproach is not very accurate, as the toolpath commanded to the machine tool may not matchthe actual toolpath travelled during machining.The latter approach, while accurate, tends to betime consuming and expensive, and requires the analysis and processing of 3D metrology data(which can be complex). Moreover, errors in the features of a machined part are not solely due to toolpath errors, and using metrology data fortoolpath verification may obfuscate toolpatherrors with process dynamics errors. In aprevious work we discussed a simple way toverify toolpath planning by overlaying the actualtool positions against the CAM generated tool positions (Vijayaraghavan, 2008). We nowdiscuss a more intuitive method to verify the effectiveness of machining toolpaths, wheredata from MTConnect-compliant machine toolsis used to create a solid model of the machined features to compare with the desired features.Related WorkThe manufacturing community has focussed extensively on developing process planning algorithms for the machining of complex parts.Elber (1995) in one of the earliest works in thefield, discussed algorithms for toolpathgeneration for 3- and 5-axis machining. Wrightet al. (2004) discussed toolpath generationalgorithms for the finish machining of freeform surfaces; the algorithms were based on thegeometric properties of the surface features. Vijayaraghavan et al. (2009) discussed methodsto vary the spacing of raster toolpaths and tooptimize the orientation of workpieces infreeform surface machining. The efficiency ofthese methods were validated primarily bymetrology and testing of the machined part. MethodologyTo verify toolpath planning effectiveness, we logthe actual cutting tool positions during machiningfrom an MTConnect-compliant machine tool,and use the positions to generate a solid modelof the machined part. The discrepancy infeatures traced by the actual toolpath relative tothe required part features can be computed by comparing these two solid models. The solidmodel of the machined part from the toolpositions can be obtained as follows:Create a 3D model of the toolCreate a 3D model of the stock materialCompute the swept volume of the tool as ittraces the tool positions (using logged data)Subtract the swept volume of the tool from thestock materialThe remaining volume of material is a solidmodel of the actual machined part.The two models can then be compared using 3D boolean difference (or subtraction) operations.ResultsWe implemented this verification scheme bylogging the cutter positions from an MTConnectcompliant 5-axis machine tool. The procedure toobtain the solid model using the tool positionswas implemented in Vericut. The two modelswere compared using a boolean diff operation in Vericut, which identified the regions in the actual machined part that were different from therequired solid model. An example applying thismethod for a feature is shown in Figure 10.FIGURE 10: A – SOLID MODEL OF REQUIRED PART; B – SOLID MODEL OF PART FROM TOOL POSITIONS SHOWING DISCREPANCIES BETWEEN ACTUAL PART FEATURES AND REQUIRED PART FEATURES. SHADED REGIONSDENOTE ~” DIFFERENCE IN MATERIAL REMOVAL.DISCUSSION AND CONCLUSIONS MTConnect makes it very easy to standardize data capture from disparate sources anddevelop common planning and verification applications. The importance of standardization cannot be overstated here – while it has always been possible to get process data from machine tools, this can be generally cumbersome andtime consuming because different machine tools require different methods of accessing data.Data analysis was also challenging to standardize as the data came in differentformats and custom subroutines were needed to process and analyze data from differentmachine tools. With MTConnect the data gathering and analysis process is standardized resulting in significant cost and time savings. This allowed us to develop the verification tools independent of the machine tools they were applied in. This also allowed us to rapidly deploy these tools in an industrial environment without any overheads (especially from the machine tool sitting idle). The toolpath verification was performed with minimal user intervention on a machine which was being actively used in a factory. The only setup needed was to initially configure the machine tool to output MTConnect-compliant data; since this is a onetime activity, it has an almost negligible impacton the long term utilization of the machine tool. Successful implementations of data capture and analysis applications over MTConnect requires a robust characterization of the data capture rates and the latency in the streaming information. Current implementations of MTConnect are over ethernet, and a data rate of about 10~100Hzwas observed in normal conditions (with no network congestion). While this is adequate for geometric analysis (such as the examples in this paper), it is not adequate for real-time process monitoring applications, such as sensor data logging. More work is needed in developing theMTConnect software libraries so that acceptable data rates and latencies can be achieved.One of the benefits of MTConnect is that it can act as a bridge between academic research and industrial practice. Researchers can developtools that operate on standardized data, whichare no longer encumbered by specific data formats and requirements. The tools can then be easily applied in industrial settings, as the framework required to implement the tools in a specific machine or system is already in place. Greater use of interoperability standards by the academic community in manufacturing research will lead to faster dissemination of research results and closer collaboration with industry. ACKNOWLEDGEMENTSWe thank the reviewers for their valuable comments. MTConnect is supported by AMT –The Association for Manufacturing Technology. We thank Armando Fox from the RAD Lab at UC Berkeley, and Paul Warndorf from AMT for their input. Research at UC Berkeley is supported by the Machine Tool Technology Research Foundation and the industrial affiliates of the Laboratory for Manufacturing and Sustainability. To learn more about the lab’s REFERENCESAltintas, Y., and Erkormaz, K., 2003, “Feedrate Optimization for Spline Interpolation In High Speed Machine Tools”, CIRP Annals –Manufacturing Technology, 52(1), pp. 297-302. de Souza, A. F., and Coelho, R. T., 2007, “Experimental Inv estigation of Feedrate Limitations on High Speed Milling Aimed at Industrial Applications”, Int. J. of Afv. Manuf. Tech, 32(11), pp. 1104–1114.Elber, G., 1995, “Freeform Surface Region Optimization for 3-Axis and 5-Axis Milling”, Computer-Aided Design, 27(6), pp. 465–470. MTConnectTM, 2008b, MTConnectTM Standard, Sencer, B., Altintas, Y., and Croft, E., 2008, “Feed Optimization for Five-axis CNC Machine Tools with Drive Constraints”, Int. J. of Mach.Tools and Manuf., 48(7), pp. 733–745. Vijayaraghavan, A., Sobel, W., Fox, A., Warndorf, P., Dornfeld, D. A., 2008, “Improving Machine Tool Interoperability with Standardized Interface Protocols”, Proceedings of ISFA. Vijayaraghavan, A., Hoover, A., Hartnett, J., and Dornfeld, D. A., 2009, “Improving Endmilli ng Surface Finish by Workpiece Rotation and Adaptive Toolpath Spacing”, Int. J. of Mach. Tools and Manuf., 49(1), pp. 89–98.World Wide Web Consortium (W3C), 2008, “Extensible Markup Language (XML),”Wright, P. K., Dornfeld, D. A., Sundararajan, V., and Misra, D., 2004, “Tool Path Generation for Finish Machining of Freeform Surfaces in the Cybercut Process Planning Pipeline”, Trans. of NAMRI/SME, 32, 159–166.毕业设计外文翻译网址。
6、毕业设计(论文)外文翻译(原文)模板
编号：桂林电子科技大学信息科技学院毕业设计(论文)外文翻译（原文）系（部）：专业：学生姓名：学号：指导教师单位：姓名：职称：年月日1、所填写内容“居中”对齐，注意每项下划线长度一致，所填字体为三号字、宋体字。
2、A4纸打印；页边距要求如下：页边距上下各为2.5 厘米，左右边距各为2.5厘米。
正文：要求为小四号Times New Roman字体，行间距取固定值（设置值为20磅）；字符间距为默认值（缩放100%，间距：标准）。
页眉处“共X页”，X需要手动修改。
大功率LED散热的研究摘要：如何提高大功率LED的散热能力，是LED器件封装和器件应用设计要解决的核心问题。
介绍并分析了国内外大功率LED散热封装技术的研究现状，总结了其发展趋势与前景用途。
关键词：大功率LED；散热；封装1. 引言发光二极管（LED ）诞生至今，已经实现了全彩化和高亮度化，并在蓝光LED 和紫光LED 的基础上开发了白光LED ，它为人类照明史又带来了一次飞跃。
发光二极管（LED）具有低耗能、省电、寿命长、耐用等优点，因而被各方看好将取代传统照明成为未来照明光源。
而大功率LED 作为第四代电光源，赋有“绿色照明光源”之称，具有体积小、安全低电压、寿命长、电光转换效率高、响应速度快、节能、环保等优良特性，必将取代传统的白炽灯、卤钨灯和荧光灯而成为21世纪的新一代光源。
普通LED 功率一般为0.05W ，工作电流为20mA ，大功率LED可以达到1W，2W，甚至数十瓦！工作电流可以是几十毫安到几百毫安不等。
其特点具有体积小、耗电小、发热小、寿命长、响应速度快、安全低电压、耐候性好、方向性好等优点。
外罩可用PC管制作，耐高温达135 度，低温-45 度。
广泛应用在油田、石化、铁路、矿山、部队等特殊行业、舞台装饰、城市景观照明、显示屏以及体育场馆等，特种工作灯具中的具有广泛的应用前景。
但由于目前大功率白光LED 的转换效率还较低，光通量较小，成本较高等方面因素的制约，因此大功率白光LED 短期内的应用主要是一些特殊领域的特种工作灯具，中长期目标才能是通用照明领域。
毕业设计(论文)外文翻译(原文)
毕业设计（论文）——外文翻译（原文）NEW APPLICATION OF DA TABASERelational databases have been in use for over two decades. A large portion of the applications of relational databases have been in the commercial world, supporting such tasks as transaction processing for banks and stock exchanges, sales and reservations for a variety of businesses, and inventory and payroll for almost of all companies. We study several new applications, which have become increasingly important in recent years.First. Decision-support systemAs the online availability of data has grown, businesses have begun to exploit the available data to make better decisions about increase sales. We can extract much information for decision support by using simple SQL queries. Recently however, people have felt the need for better decision support based on data analysis and data mining, or knowledge discovery, using data from a variety of sources.Database applications can be broadly classified into transaction processing and decision support. Transaction-processing systems are widely used today, and companies have accumulated a vast amount of information generated by these systems.The term data mining refers loosely to finding relevant information, or “discovering knowledge,”from a large volume of data. Like knowledge discovery in artificial intelligence, data mining attempts to discover statistical rules and patterns automatically from data. However, data mining differs from machine learning in that it deals with large volumes of data, stored primarily on disk.Knowledge discovered from a database can be represented by a set of rules. We can discover rules from database using one of two models:In the first model, the user is involved directly in the process of knowledge discovery.In the second model, the system is responsible for automatically discovering knowledge from the database, by detecting patterns and correlations in the data.Work on automatic discovery of rules has been influenced strongly by work in the artificial-intelligence community on machine learning. The main differences lie in the volume of data handled in databases, and in the need to access disk. Specialized data-mining algorithms have been developed to handle large volumes of disk-resident data efficiently.The manner in which rules are discovered depends on the class of data-mining application. We illustrate rule discovery using two application classes: classification and associations.Second. Spatial and Geographic DatabasesSpatial databases store information related to spatial locations, and provide support for efficient querying and indexing based on spatial locations. Two types of spatial databases are particularly important:Design databases, or computer-aided-design (CAD) databases, are spatial databases used to store design information about how objects---such as buildings, cars or aircraft---are constructed. Other important examples of computer-aided-design databases are integrated-circuit and electronic-device layouts.Geographic databases are spatial databases used to store geographic information, such as maps. Geographic databases are often called geographic information systems.Geographic data are spatial in nature, but differ from design data in certain ways. Maps and satellite images are typical examples of geographic data. Maps may provide not only location information -suchas boundaries, rivers and roads---but also much more detailed information associated with locations, such as elevation, soil type, land usage, and annual rainfall.Geographic data can be categorized into two types: raster data (such data consist a bit maps or pixel maps, in two or more dimensions.), vector data (vector data are constructed from basic geographic objects). Map data are often represented in vector format.Third. Multimedia DatabasesRecently, there has been much interest in databases that store multimedia data, such as images, audio, and video. Today multimedia data typically are stored outside the database, in files systems. When the number of multimedia objects is relatively small, features provided by databases are usually not important. Database functionality becomes important when the number of multimedia objects stored is large. Issues such as transactional updates, querying facilities, and indexing then become important. Multimedia objects often have descriptive attributes, such as those indicating when they were created, who created them, and to what category they belong. One approach to building a database for such multimedia objects is to use database for storing the descriptive attributes, and for keeping track of the files in which the multimedia objects are stored.However, storing multimedia outside the database makes it harder to provide database functionality, such as indexing on the basis of actual multimedia data content. It can also lead to inconsistencies, such a file that is noted in the database, but whose contents are missing, or vice versa. It is therefore desirable to store the data themselves in the database.Forth. Mobility and Personal DatabasesLarge-scale commercial databases have traditionally been stored in central computing facilities. In the case of distributed database applications, there has usually been strong central database and network administration. Two technology trends have combined to create applications in which this assumption of central control and administration is not entirely correct:1.The increasingly widespread use of personal computers, and, more important, of laptop or “notebook” computers.2.The development of a relatively low-cost wireless digital communication infrastructure, base on wireless local-area networks, cellular digital packet networks, and other technologies.Wireless computing creates a situation where machines no longer have fixed locations and network addresses. This complicates query processing, since it becomes difficult to determine the optimal location at which to materialize the result of a query. In some cases, the location of the user is a parameter of the query. A example is a traveler’s information system that provides data on hotels, roadside services, and the like to motorists. Queries about services that are ahead on the current route must be processed based on knowledge of the user’s location, direction of motion, and speed.Energy (battery power) is a scarce resource for mobile computers. This limitation influences many aspects of system design. Among the more interesting consequences of the need for energy efficiency is the use of scheduled data broadcasts to reduce the need for mobile system to transmit queries. Increasingly amounts of data may reside on machines administered by users, rather than by database administrators. Furthermore, these machines may, at times, be disconnected from the network.SummaryDecision-support systems are gaining importance, as companies realize the value of the on-line data collected by their on-line transaction-processing systems. Proposed extensions to SQL, such as the cube operation, help to support generation of summary data. Data mining seeks to discoverknowledge automatically, in the form of statistical rules and patterns from large databases. Data visualization systems help humans to discover such knowledge visually.Spatial databases are finding increasing use today to store computer-aided design data as well as geographic data. Design data are stored primarily as vector data; geographic data consist of a combination of vector and raster data.Multimedia databases are growing in importance. Issues such as similarity-based retrieval and delivery of data at guaranteed rates are topics of current research.Mobile computing systems have become common, leading to interest in database systems that can run on such systems. Query processing in such systems may involve lookups on server database.毕业设计（论文）——外文翻译（译文）数据库的新应用我们使用关系数据库已经有20多年了，关系数据库应用中有很大一部分都用于商业领域支持诸如银行和证券交易所的事务处理、各种业务的销售和预约，以及几乎所有公司都需要的财产目录和工资单管理。
毕设外文翻译电子版
7.1 INTRODUCTIONAfter lathes, milling machines are the most widely used for manufacturing applications. In milling, the workpiece is fed into a rotating milling cutter, which is a multi-point tool as shown in Fig. 7.1, unlike a lathe, which uses a single point cutting tool. The tool used in milling is called the milling cutter.Fig. 7.1Schematic diagram of a milling operationThe milling process is characterised by:(i)Interrupted cutting Each of the cutting edges removes materialfor only a part of the rotation of the milling cutter. As a result, the cutting edge has time to cool before it again removes material.Thus the milling operation is much more cooler compared to the turning operation. This allows for a much larger material rates.(ii)Small size of chips Though the size of the chips is small, in view of the multiple cutting edges in contact a large amount of material is removed and as a result the component is generally completed ina single pass unlike the turning process which requires a largenumber of cuts for finishing.(iii)Variation in chip thickness This contributes to the non-steady state cyclic conditions of varying cutting forces during the contact of the cutting edge with the chip thickness varying from zero to maximum size or vice versa. This cyclic variation of the force can excite any of the natural frequencies of the machine tool system and is harmful to the tool life and surface finish generatedA milling machine is one of the most versatile machine tools. It is adaptable for quantity production as well as in job shops and tool rooms. The versatility of milling is because of the large variety of accessories and tools available with milling machines. The typical tolerance expected from the process is about ±0.050 mm.7.2 TYPES OF MILLING MACHINESTo satisfy various requirements milling machines come in a number of sizes and varieties. In view of the large material removal ratesmilling machines come with a very rigid spindle and large power. The varieties of milling machines available are:(i) Knee and Column type(a) horizontal(b) vertical(c) universal(d) turret typeThese are the general purpose milling machines, which have a high degree of flexibility and are employed for all types of works including batch manufacturing. A large variety of attachments to improve the flexibility are available for this class of milling machines.(ii) Production (Bed) type(a) simplex(b) duplex(c) triplexThese machines are generally meant for regular production involving large batch sizes. The flexibility is relatively less in these machines which is suitable for productivity enhancement.(iii) Plano millersThese machines are used only for very large workpieces involving table travels in meters.(iv) Special type(a) Rotary table(b) Drum type(c) Copy milling (Die sinking machines)(d) Key way milling machines(e) Spline shaft milling machinesThese machines provide special facilities to suit specific applications that are not catered to by the other classes of milling machines.7.2.1 Knee and Column Milling MachinesThe knee(升降台) and column type is the most commonly used machine in view of its flexibility and easier setup. A typical machine construction is shown in Fig. 7.2 for the horizontal axis. The knee houses the feed mechanism and mounts the saddle and table. The table basically has the T-slots running along the X-axis for the purpose of work holding. The table moves along the X-axis on the saddle while the saddle moves along the Y-axis on the guide ways provided on the knee.The feed is provided either manually with a hand wheel or connected for automatic by the lead screw, which in turn is coupled to the main spindle drive. The knee can move up and down (Z-axis) on a dovetail provided on the column.Fig. 7.2 Horizontal knee and column type milling machineThe massive column at the back of the machine houses all the power train including the motor and the spindle gearbox. The power for feeding the table lead screw is taken from the main motor through a separate feed gearbox. Sometimes a separate feed motor is provided for the feed gearbox as well.While the longitudinal and traverse motions are provided with automatic motion, the raising of the knee is generally made manually.The spindle is located at the top end of the column. The arbour used to mount the milling cutters is mounted in the spindle and is provided with a support on the other end to take care of the heavy cutting forces by means of an overarm with bearing. As shown in Fig.7.2 the overarm extends from the column with a rigid design. The spindle nose has the standard Morse taper of the suitable sizedepending upon the machine size.The milling cutters are mounted on the arbour at any desired position, the rest of the length being filled by standard hardened collars of varying widths to fix the position of the cutter. The arbour is clamped in the spindle with the help of a draw bar and then fixed with nuts.Milling machines are generally specified on the following basis:(i) Size of the table, which specifies the actual working area on the table and relates to the maximum size of the workpiece that can be accommodated.(ii) Amount of table travel, which gives the maximum axis movement that is possible.(iii) Horse power of the spindle, which actually specifies the power of the spindle motor used. Smaller machines may come with 1 to 3 hp while the production machines may go from 10 to 50 hp.Another type of knee and column milling machine is the vertical axis type. Its construction is very similar to the horizontal axis type, except for the spindle type and location.The vertical axis milling machine is relatively more flexible (Fig. 7.4) and suitable for machining complex cavities such as die cavities in tool rooms. The vertical head is provided with a swiveling facility in horizontal direction whereby the cutter axis can be swivelled. This isuseful for tool rooms where more complex milling operations are carried out.The spindle is located in the vertical direction and is suitable for using the shank mounted milling cutters such as end mills, In view of the location of the tool, the setting up of the workpiece and observing the machining operation is more convenient.Fig, 7.3 Vertical knee and column type milling machineFig.7.4 Some of the milling operations normally carried out on vertical axis machinesThe universal machine has the table which can be swivelled in a horizontal plane at about 45o to either the left or right. This makes the universal machine suitable for milling spur and helical gears as well as worm gears and cams.7.2.2 Bed Type Milling MachineIn production milling machines it is desirable to increase the metal removal rates. If it is done on conventional machines by increasingthe depth of cut, there is possibility of chatter. Hence another varietyof milling machines named as bed type machines are used which are made more rugged and are capable of removing more material. The ruggedness is obtained as a consequence of the reduction in versatility.The table in the case of bed type machines is directly mounted on the bed and is provided with only longitudinal motion.The spindle moves along with the column to provide the cutting action. Simplex machines (Fig. 7.5) are the ones with only one spindle head while duplex machines have two spindles (Fig. 7.6). The two spindles are located on either side of a heavy workpiece and remove material from both sides simultaneously.Fig. 7.5 Simplex bed type milling machineFig. 7.6 Duplex bed type milling machine7.3 MILLING CUTTERSThere are a large variety of milling cutters available to suit specific requirements. The versatility of the milling machine is contributed toa great extent by the variety of milling cutters that are available.7.3.1 Types of Milling CuttersMilling cutters are classified into various types based on a variety of methods.(i) Based on construction:(a) Solid(b) Inserted tooth typeBased on mounting:(a) Arbor mounted(b) Shank mounted(c) Nose mountedBase on rotation:(a) Right hand rotation (counter clockwise)(b) Left hand rotation (clockwise)Based on helix:(a) Right hand helix(b) Left hand helixMilling cutters are generally made of high speed steel or cemented carbides. The cemented carbide cutters can be of a brazed tip variety or with indexable tips. The indexable variety is more common since it is normally less expensive to replace the worn out cutting edges than to regrind them.Plain milling cutters These are also called slab milling cutters and are basically cylindrical with the cutting teeth on the periphery as shown in Fig. 7.7. These are generally used for machining flat surfaces.Fig. 7.7 Arbor mounted milling cutters for general purposeLight duty slab milling cutters generally have a face width, which is small of the order of 25 mm. They generally have straight teeth and large number of teeth.Heavy duty slab milling cutters come with a smaller number of teeth to allow for more chip space. This allows taking deeper cuts and consequently high material removal rates.Helical milling cutters have a very small number of teeth but a large helix angle. This type of cutter cuts with a shearing action, which can produce a very fine finish. The large helix angle allows the cutter to absorb most of the end load and therefore the cutter enters and leaves the workpiece very smoothly.Side and face milling cutters These have the cutting edges not only onthe face like the slab milling cutters, but also on both the sides. As aresult, these cutters become more versatile since they can be used for side milling as well as for slot milling.Staggered tooth side milling cutters are a variation where the teeth are arranged in an alternate helix pattern. This type is generally used for milling deep slots, since the staggering of teeth provides for greater chip space.Another variation of the side and face cutter is the half side milling cutter, which has cutting edges only on one side. This arrangement provides a positive rake angle and is useful for machining on only one side. These have a much smoother cutting action and a long tool life. The power consumed is also less for these cutters.Fig. 7.8Special forms of arbor mounted milling cuttersSlitting saws The other common form of milling cutters in the arbor mounted category is the slitting saw. This is very similar to a saw blade inappearance as well as function. Most of these have teeth around the circumference while some have side teeth as well. The thickness of these cutters is generally very small and is used for cutting off operations or for deep slots.Special form cutters In addition to the general type of milling cutters described above, there are a large number of special form milling cutters available which are used for machining specific profiles.Angular milling cutters are made in single or double angle cutters for milling any angle such as 30, 45 or 60o Form relieved cutters are made of various shapes such as circular, corner rounding, convex or concave shapes.T-slot milling cutters are used for milling T-slots such as those in the milling machine table. The central slot is to be milled first using an end mill before using the T-slot milling cutter. Woodruff key seat milling cutters are used for milling as the name suggests, woodruff key seats Some other special form cutters are dovetail milling cutters and gear milling cutters.End mills These are shank mounted as shown in Fig. 7.9 and are generally used in vertical axis milling machines. They are used for milling slots, key ways and pockets where other type of milling cutters cannot be used. A depth of cut of almost half the diameter can be taken with the end mills.The end mills have the cutting edge running through the length of the cutting portion as well as on the face radially up to a certain length. The helix angle of the cutting edge promotes smooth and efficient cutting even at high cutting speeds and feed rates. High cutting speeds(转速?) are generally recommended for this type of milling cutters.Fig. 7.9 Shank mounted milling cutters and various types of end mills There are a large variety of end mills. One of the distinctions is based on the method of holding, i.e., the end mill shank can be straight or tapered. The straight shank is used on end mills of small size and held in the milling machine spindle with the help of a suitable collet. The tapered shank can be directly mounted in the spindle with the help of the selfholding taper. If the taper is small compared to the spindle taper, then an adopter accommodating both the tapers is used.The end teeth of the end mills may be terminated at a distance from the cutter center or may proceed till the center (Fig. 7.9 f). Those with the cutting edge up to the center are called slot drills or end cutting end mills since they have the ability to cut into the solid material (Fig. 7.9 g). The other type of end mills which have a larger number of teeth cannot cut into solid material and hence require a pilot hole drilled before a pocket is machined.The cutting edge along the side of an end mill is generally straight and sometimes can be tapered by grinding on a tool and cutter grinder such that the draft required for mould and die cavities can be automatically generated.。
毕业设计英文 翻译(原文)
编号：毕业设计(论文)外文翻译（原文）院（系）：桂林电子科技大学专业：电子信息工程学生姓名： xx学号： xxxxxxxxxxxxx 指导教师单位：桂林电子科技大学姓名： xxxx职称： xx2014年x月xx日Timing on and off power supplyusesThe switching power supply products are widely used in industrial automation and control, military equipment, scientific equipment, LED lighting, industrial equipment,communications equipment,electrical equipment,instrumentation, medical equipment, semiconductor cooling and heating, air purifiers, electronic refrigerator, LCD monitor, LED lighting, communications equipment, audio-visual products, security, computer chassis, digital products and equipment and other fields.IntroductionWith the rapid development of power electronics technology, power electronics equipment and people's work, the relationship of life become increasingly close, and electronic equipment without reliable power, into the 1980s, computer power and the full realization of the switching power supply, the first to complete the computer Power new generation to enter the switching power supply in the 1990s have entered into a variety of electronic, electrical devices, program-controlled switchboards, communications, electronic testing equipment power control equipment, power supply, etc. have been widely used in switching power supply, but also to promote the rapid development of the switching power supply technology .Switching power supply is the use of modern power electronics technology to control the ratio of the switching transistor to turn on and off to maintain a stable output voltage power supply, switching power supply is generally controlled by pulse width modulation (PWM) ICs and switching devices (MOSFET, BJT) composition. Switching power supply and linear power compared to both the cost and growth with the increase of output power, but the two different growth rates. A power point, linear power supply costs, but higher than the switching power supply. With the development of power electronics technology and innovation, making the switching power supply technology to continue to innovate, the turning points of this cost is increasingly move to the low output power side, the switching power supply provides a broad space for development.The direction of its development is the high-frequency switching power supply, high frequency switching power supply miniaturization, and switching power supply into a wider range of application areas, especially in high-tech fields, and promote the miniaturization of high-tech products, light of. In addition, the development and application of the switching power supply in terms of energy conservation, resource conservation and environmental protection are of great significance.classificationModern switching power supply, there are two: one is the DC switching power supply; the other is the AC switching power supply. Introduces only DC switching power supply and its function is poor power quality of the original eco-power (coarse) - such as mains power or battery power, converted to meet the equipment requirements of high-quality DC voltage (Varitronix) . The core of the DC switching power supply DC / DC converter. DC switching power supply classification is dependent on the classification of DC / DC converter. In other words, the classification of the classification of the DC switching power supply and DC/DC converter is the classification of essentially the same, the DC / DC converter is basically a classification of the DC switching power supply.DC /DC converter between the input and output electrical isolation can be divided into two categories: one is isolated called isolated DC/DC converter; the other is not isolated as non-isolated DC / DC converter.Isolated DC / DC converter can also be classified by the number of active power devices. The single tube of DC / DC converter Forward (Forward), Feedback (Feedback) two. The double-barreled double-barreled DC/ DC converter Forward (Double Transistor Forward Converter), twin-tube feedback (Double Transistor Feedback Converter), Push-Pull (Push the Pull Converter) and half-bridge (Half-Bridge Converter) four. Four DC / DC converter is the full-bridge DC / DC converter (Full-Bridge Converter).Non-isolated DC / DC converter, according to the number of active power devices can be divided into single-tube, double pipe, and four three categories. Single tube to a total of six of the DC / DC converter, step-down (Buck) DC / DC converter, step-up (Boost) DC / DC converters, DC / DC converter, boost buck (Buck Boost) device of Cuk the DC / DC converter, the Zeta DC / DC converter and SEPIC, the DC / DC converter. DC / DC converters, the Buck and Boost type DC / DC converter is the basic buck-boost of Cuk, Zeta, SEPIC, type DC / DC converter is derived from a single tube in this six. The twin-tube cascaded double-barreled boost (buck-boost) DC / DC converter DC / DC converter. Four DC / DC converter is used, the full-bridge DC / DC converter (Full-Bridge Converter).Isolated DC / DC converter input and output electrical isolation is usually transformer to achieve the function of the transformer has a transformer, so conducive to the expansion of the converter output range of applications, but also easy to achieve different voltage output , or a variety of the same voltage output.Power switch voltage and current rating, the converter's output power is usually proportional to the number of switch. The more the number of switch, the greater the output power of the DC / DC converter, four type than the two output power is twice as large,single-tube output power of only four 1/4.A combination of non-isolated converters and isolated converters can be a single converter does not have their own characteristics. Energy transmission points, one-way transmission and two-way transmission of two DC / DC converter. DC / DC converter with bi-directional transmission function, either side of the transmission power from the power of lateral load power from the load-lateral side of the transmission power.DC / DC converter can be divided into self-excited and separately controlled. With the positive feedback signal converter to switch to self-sustaining periodic switching converter, called self-excited converter, such as the the Luo Yeer (Royer,) converter is a typical push-pull self-oscillating converter. Controlled DC / DC converter switching device control signal is generated by specialized external control circuit.the switching power supply.People in the field of switching power supply technology side of the development of power electronic devices, while the development of the switching inverter technology, the two promote each other to promote the switching power supply annual growth rate of more than two digits toward the light, small, thin, low-noise, high reliability, the direction of development of anti-jamming. Switching power supply can be divided into AC / DC and DC / DC two categories, AC / AC DC / AC, such as inverters, DC / DC converter is now modular design technology and production processes at home and abroad have already matured and standardization, and has been recognized by the user, but AC / DC modular, its own characteristics make the modular process, encounter more complex technology and manufacturing process. Hereinafter to illustrate the structure and characteristics of the two types of switching power supply.Self-excited: no external signal source can be self-oscillation, completely self-excited to see it as feedback oscillation circuit of a transformer.Separate excitation: entirely dependent on external sustain oscillations, excited used widely in practical applications. According to the excitation signal structure classification; can be divided into pulse-width-modulated and pulse amplitude modulated two pulse width modulated control the width of the signal is frequency, pulse amplitude modulation control signal amplitude between the same effect are the oscillation frequency to maintain within a certain range to achieve the effect of voltage stability. The winding of the transformer can generally be divided into three types, one group is involved in the oscillation of the primary winding, a group of sustained oscillations in the feedback winding, there is a group of load winding. Such as Shanghai is used in household appliances art technological production of switching power supply, 220V AC bridge rectifier, changing to about 300V DC filter added tothe collector of the switch into the transformer for high frequency oscillation, the feedback winding feedback to the base to maintain the circuit oscillating load winding induction signal, the DC voltage by the rectifier, filter, regulator to provide power to the load. Load winding to provide power at the same time, take up the ability to voltage stability, the principle is the voltage output circuit connected to a voltage sampling device to monitor the output voltage changes, and timely feedback to the oscillator circuit to adjust the oscillation frequency, so as to achieve stable voltage purposes, in order to avoid the interference of the circuit, the feedback voltage back to the oscillator circuit with optocoupler isolation.technology developmentsThe high-frequency switching power supply is the direction of its development, high-frequency switching power supply miniaturization, and switching power supply into the broader field of application, especially in high-tech fields, and promote the development and advancement of the switching power supply, an annual more than two-digit growth rate toward the light, small, thin, low noise, high reliability, the direction of the anti-jamming. Switching power supply can be divided into AC / DC and DC / DC two categories, the DC / DC converter is now modular design technology and production processes at home and abroad have already matured and standardized, and has been recognized by the user, but modular AC / DC, because of its own characteristics makes the modular process, encounter more complex technology and manufacturing process. In addition, the development and application of the switching power supply in terms of energy conservation, resource conservation and environmental protection are of great significance.The switching power supply applications in power electronic devices as diodes, IGBT and MOSFET.SCR switching power supply input rectifier circuit and soft start circuit, a small amount of applications, the GTR drive difficult, low switching frequency, gradually replace the IGBT and MOSFET.Direction of development of the switching power supply is a high-frequency, high reliability, low power, low noise, jamming and modular. Small, thin, and the key technology is the high frequency switching power supply light, so foreign major switching power supply manufacturers have committed to synchronize the development of new intelligent components, in particular, is to improve the secondary rectifier loss, and the power of iron Oxygen materials to increase scientific and technological innovation in order to improve the magnetic properties of high frequency and large magnetic flux density (Bs), and capacitor miniaturization is a key technology. SMT technology allows the switching power supply has made considerable progress, the arrangement of the components in the circuit board on bothsides, to ensure that the light of the switching power supply, a small, thin. High-frequency switching power supply is bound to the traditional PWM switching technology innovation, realization of ZVS, ZCS soft-switching technology has become the mainstream technology of the switching power supply, and a substantial increase in the efficiency of the switching power supply. Indicators for high reliability, switching power supply manufacturers in the United States by reducing the operating current, reducing the junction temperature and other measures to reduce the stress of the device, greatly improve the reliability of products.Modularity is the overall trend of switching power supply, distributed power systems can be composed of modular power supply, can be designed to N +1 redundant power system, and the parallel capacity expansion. For this shortcoming of the switching power supply running noise, separate the pursuit of high frequency noise will also increase, while the use of part of the resonant converter circuit technology to achieve high frequency, in theory, but also reduce noise, but some The practical application of the resonant converter technology, there are still technical problems, it is still a lot of work in this field, so that the technology to be practical.Power electronics technology innovation, switching power supply industry has broad prospects for development. To accelerate the pace of development of the switching power supply industry in China, it must take the road of technological innovation, out of joint production and research development path with Chinese characteristics and contribute to the rapid development of China's national economy.Developments and trends of the switching power supply1955 U.S. Royer (Roger) invented the self-oscillating push-pull transistor single-transformer DC-DC converter is the beginning of the high-frequency conversion control circuit 1957 check race Jen, Sen, invented a self-oscillating push-pull dual transformers, 1964, U.S. scientists canceled frequency transformer in series the idea of switching power supply, the power supply to the size and weight of the decline in a fundamental way. 1969 increased due to the pressure of the high-power silicon transistor, diode reverse recovery time shortened and other components to improve, and finally made a 25-kHz switching power supply.At present, the switching power supply to the small, lightweight and high efficiency characteristics are widely used in a variety of computer-oriented terminal equipment, communications equipment, etc. Almost all electronic equipment is indispensable for a rapid development of today's electronic information industry power mode. Bipolar transistor made of 100kHz, 500kHz power MOS-FET made, though already the practical switching power supply is currently available on the market, but its frequency to be further improved. Toimprove the switching frequency, it is necessary to reduce the switching losses, and to reduce the switching losses, the need for high-speed switch components. However, the switching speed will be affected by the distribution of the charge stored in the inductance and capacitance, or diode circuit to produce a surge or noise. This will not only affect the surrounding electronic equipment, but also greatly reduce the reliability of the power supply itself. Which, in order to prevent the switching Kai - closed the voltage surge, RC or LC buffers can be used, and the current surge can be caused by the diode stored charge of amorphous and other core made of magnetic buffer . However, the high frequency more than 1MHz, the resonant circuit to make the switch on the voltage or current through the switch was a sine wave, which can reduce switching losses, but also to control the occurrence of surges. This switch is called the resonant switch. Of this switching power supply is active, you can, in theory, because in this way do not need to greatly improve the switching speed of the switching losses reduced to zero, and the noise is expected to become one of the high-frequency switching power supply The main ways. At present, many countries in the world are committed to several trillion Hz converter utility.the principle of IntroductionThe switching power supply of the process is quite easy to understand, linear power supplies, power transistors operating in the linear mode and linear power, the PWM switching power supply to the power transistor turns on and off state, in both states, on the power transistor V - security product is very small (conduction, low voltage, large current; shutdown, voltage, current) V oltammetric product / power device is power semiconductor devices on the loss.Compared with the linear power supply, the PWM switching power supply more efficient process is achieved by "chopping", that is cut into the amplitude of the input DC voltage equal to the input voltage amplitude of the pulse voltage. The pulse duty cycle is adjusted by the switching power supply controller. Once the input voltage is cut into the AC square wave, its amplitude through the transformer to raise or lower. Number of groups of output voltage can be increased by increasing the number of primary and secondary windings of the transformer. After the last AC waveform after the rectifier filter the DC output voltage.The main purpose of the controller is to maintain the stability of the output voltage, the course of their work is very similar to the linear form of the controller. That is the function blocks of the controller, the voltage reference and error amplifier can be designed the same as the linear regulator. Their difference lies in the error amplifier output (error voltage) in the drive before the power tube to go through a voltage / pulse-width conversion unit.Switching power supply There are two main ways of working: Forward transformand boost transformation. Although they are all part of the layout difference is small, but the course of their work vary greatly, have advantages in specific applications.the circuit schematicThe so-called switching power supply, as the name implies, is a door, a door power through a closed power to stop by, then what is the door, the switching power supply using SCR, some switch, these two component performance is similar, are relying on the base switch control pole (SCR), coupled with the pulse signal to complete the on and off, the pulse signal is half attentive to control the pole voltage increases, the switch or transistor conduction, the filter output voltage of 300V, 220V rectifier conduction, transmitted through the switching transformer secondary through the transformer to the voltage increase or decrease for each circuit work. Oscillation pulse of negative semi-attentive to the power regulator, base, or SCR control voltage lower than the original set voltage power regulator cut-off, 300V power is off, switch the transformer secondary no voltage, then each circuit The required operating voltage, depends on this secondary road rectifier filter capacitor discharge to maintain. Repeat the process until the next pulse cycle is a half weeks when the signal arrival. This switch transformer is called the high-frequency transformer, because the operating frequency is higher than the 50HZ low frequency. Then promote the pulse of the switch or SCR, which requires the oscillator circuit, we know, the transistor has a characteristic, is the base-emitter voltage is 0.65-0.7V is the zoom state, 0.7V These are the saturated hydraulic conductivity state-0.1V-0.3V in the oscillatory state, then the operating point after a good tune, to rely on the deep negative feedback to generate a negative pressure, so that the oscillating tube onset, the frequency of the oscillating tube capacitor charging and discharging of the length of time from the base to determine the oscillation frequency of the output pulse amplitude, and vice versa on the small, which determines the size of the output voltage of the power regulator. Transformer secondary output voltage regulator, usually switching transformer, single around a set of coils, the voltage at its upper end, as the reference voltage after the rectifier filter, then through the optocoupler, this benchmark voltage return to the base of the oscillating tube pole to adjust the level of the oscillation frequency, if the transformer secondary voltage is increased, the sampling coil output voltage increases, the positive feedback voltage obtained through the optocoupler is also increased, this voltage is applied oscillating tube base, so that oscillation frequency is reduced, played a stable secondary output voltage stability, too small do not have to go into detail, nor it is necessary to understand the fine, such a high-power voltage transformer by switching transmission, separated and after the class returned by sampling the voltage from the opto-coupler pass separated after class, so before the mains voltage, and after the classseparation, which is called cold plate, it is safe, transformers before power is independent, which is called switching power supply.the DC / DC conversionDC / DC converter is a fixed DC voltage transformation into a variable DC voltage, also known as the DC chopper. There are two ways of working chopper, one Ts constant pulse width modulation mode, change the ton (General), the second is the frequency modulation, the same ton to change the Ts, (easy to produce interference). Circuit by the following categories:Buck circuit - the step-down chopper, the average output voltage U0 is less than the input voltage Ui, the same polarity.Boost Circuit - step-up chopper, the average output voltage switching power supply schematic U0 is greater than the input voltage Ui, the same polarity.Buck-Boost circuit - buck or boost chopper, the output average voltage U0 is greater than or less than the input voltage Ui, the opposite polarity, the inductance transmission.Cuk circuit - a buck or boost chopper, the output average voltage U0 is greater than or less than the input voltage Ui, the opposite polarity, capacitance transmission.The above-mentioned non-isolated circuit, the isolation circuit forward circuits, feedback circuit, the half-bridge circuit, the full bridge circuit, push-pull circuit. Today's soft-switching technology makes a qualitative leap in the DC / DC the U.S. VICOR company design and manufacture a variety of ECI soft-switching DC / DC converter, the maximum output power 300W, 600W, 800W, etc., the corresponding power density (6.2 , 10,17) W/cm3 efficiency (80-90)%. A the Japanese Nemic Lambda latest using soft-switching technology, high frequency switching power supply module RM Series, its switching frequency (200 to 300) kHz, power density has reached 27W/cm3 with synchronous rectifier (MOSFETs instead of Schottky diodes ), so that the whole circuit efficiency by up to 90%.AC / DC conversionAC / DC conversion will transform AC to DC, the power flow can be bi-directional power flow by the power flow to load known as the "rectification", referred to as "active inverter power flow returned by the load power. AC / DC converter input 50/60Hz AC due must be rectified, filtered, so the volume is relatively large filter capacitor is essential, while experiencing safety standards (such as UL, CCEE, etc.) and EMC Directive restrictions (such as IEC, FCC, CSA) in the AC input side must be added to the EMC filter and use meets the safety standards of the components, thus limiting the miniaturization of the volume of AC / DC power, In addition, due to internal frequency, high voltage, current switching, making the problem difficult to solve EMC also high demands on the internal high-density mountingcircuit design, for the same reason, the high voltage, high current switch makes power supply loss increases, limiting the AC / DC converter modular process, and therefore must be used to power system optimal design method to make it work efficiency to reach a certain level of satisfaction.AC / DC conversion circuit wiring can be divided into half-wave circuit, full-wave circuit. Press the power phase can be divided into single-phase three-phase, multiphase. Can be divided into a quadrant, two quadrant, three quadrants, four-quadrant circuit work quadrant.he selection of the switching power supplySwitching power supply input on the anti-jamming performance, compared to its circuit structure characteristics (multi-level series), the input disturbances, such as surge voltage is difficult to pass on the stability of the output voltage of the technical indicators and linear power have greater advantages, the output voltage stability up to (0.5)%. Switching power supply module as an integrated power electronic devices should be selected。
本科毕业设计外文文献及译文1
本科毕业设计外文文献及译文文献、资料题目：Transit Route Network Design Problem:Review文献、资料来源：网络文献、资料发表（出版）日期：2007.1院（部）：xxx专业：xxx班级：xxx姓名：xxx学号：xxx指导教师：xxx翻译日期：xxx外文文献：Transit Route Network Design Problem:Review Abstract:Efficient design of public transportation networks has attracted much interest in the transport literature and practice,with manymodels and approaches for formulating the associated transit route network design problem _TRNDP_having been developed.The presentpaper systematically presents and reviews research on the TRNDP based on the three distinctive parts of the TRNDP setup:designobjectives,operating environment parameters and solution approach.IntroductionPublic transportation is largely considered as a viable option for sustainable transportation in urban areas,offering advantages such as mobility enhancement,traffic congestion and air pollution reduction,and energy conservation while still preserving social equity considerations. Nevertheless,in the past decades,factors such as socioeconomic growth,the need for personalized mobility,the increase in private vehicle ownership and urban sprawl have led to a shift towards private vehicles and a decrease in public transportation’s share in daily commuting (Sinha2003;TRB2001;EMTA2004;ECMT2002;Pucher et al.2007).Efforts for encouraging public transportation use focuses on improving provided services such as line capacity,service frequency,coverage,reliability,comfort and service quality which are among the most important parameters for an efficient public transportation system(Sinha2003;Vuchic2004.) In this context,planning and designing a cost and service efficientpublic transportation network is necessary for improving its competitiveness and market share. The problem that formally describes the design of such a public transportation network is referred to as the transit route network design problem(TRNDP);it focuses on the optimization of a number of objectives representing the efficiency of public transportation networks under operational and resource constraints such as the number and length of public transportation routes, allowable service frequencies,and number of available buses(Chakroborty2003;Fan and Machemehl2006a,b).The practical importance of designing public transportation networks has attractedconsiderable interest in the research community which has developed a variety of approaches and modelsfor the TRNDP including different levels of design detail and complexity as well as interesting algorithmic innovations.In thispaper we offer a structured review of approaches for the TRNDP;researchers will obtain a basis for evaluating existing research and identifying future research paths for further improving TRNDP models.Moreover,practitioners will acquire a detailed presentation of both the process and potential tools for automating the design of public transportation networks,their characteristics,capabilities,and strengths.Design of Public Transportation NetworksNetwork design is an important part of the public transportation operational planning process_Ceder2001_.It includes the design of route layouts and the determination of associated operational characteristics such as frequencies,rolling stock types,and so on As noted by Ceder and Wilson_1986_,network design elements are part of the overall operational planning process for public transportation networks;the process includes five steps:_1_design of routes;_2_ setting frequencies;_3_developing timetables;_4_scheduling buses;and_5_scheduling drivers. Route layout design is guided by passenger flows:routes are established to provide direct or indirect connection between locations and areas that generate and attract demand for transit travel, such as residential and activity related centers_Levinson1992_.For example,passenger flows between a central business district_CBD_and suburbs dictate the design of radial routes while demand for trips between different neighborhoods may lead to the selection of a circular route connecting them.Anticipated service coverage,transfers,desirable route shapes,and available resources usually determine the structure of the route network.Route shapes areusually constrained by their length and directness_route directness implies that route shapes are as straight as possible between connected points_,the usage of given roads,and the overlapping with other transit routes.The desirable outcome is a set of routesconnecting locations within a service area,conforming to given design criteria.For each route, frequencies and bus types are the operational characteristics typically determined through design. Calculations are based on expected passenger volumes along routes that are estimated empirically or by applying transit assignmenttechniques,under frequency requirement constraints_minimum and maximum allowedfrequencies guaranteeing safety and tolerable waiting times,respectively_,desired load factors, fleet size,and availability.These steps as well as the overall design.process have been largely based upon practical guidelines,the expert judgment of transit planners,and operators experience_Baaj and Mahmassani1991_.Two handbooks by Black _1995_and Vuchic_2004_outline frameworks to be followed by planners when designing a public transportation network that include:_1_establishing the objectives for the network;_2_ defining the operational environment of the network_road structure,demand patterns,and characteristics_;_3_developing;and_4_evaluating alternative public transportation networks.Despite the extensive use of practical guidelines and experience for designing transit networks,researchers have argued that empirical rules may not be sufficient for designing an efficient transit network and improvements may lead to better quality and more efficient services. For example,Fan and Machemehl_2004_noted that researchers and practitioners have been realizing that systematic and integrated approaches are essential for designing economically and operationally efficient transit networks.A systematic design process implies clear and consistent steps and associated techniques for designing a public transportation network,which is the scope of the TRNDP.TRNDP:OverviewResearch has extensively examined the TRNDP since the late1960s.In1979,Newell discussed previous research on the optimal design of bus routes and Hasselström_1981_ analyzed relevant studies and identified the major features of the TRNDP as demand characteristics,objective functions,constraints,passengerbehavior,solution techniques,and computational time for solving the problem.An extensive review of existing work on transit network design was provided by Chua_1984_who reported five types of transit system planning:_1_manual;_2_marketanalysis;_3_systems analysis;_4_systems analysis with interactive graphics;and_5_ mathematical optimization approach.Axhausemm and Smith_1984_analyzed existing heuristic algorithms for formulating the TRNDP in Europe,tested them,anddiscussed their potential implementation in the United States.Ceder and Wilson_1986_reportedprior work on the TRNDP and distinguished studies into those that deal with idealized networks and to those that focus on actual routes,suggesting that the main features of the TRNDP include demand characteristics,objectivesand constraints,and solution methods.At the same period,Van Nes et al._1988_grouped TRNDP models into six categories:_1_ analytical models for relating parameters of the public transportation system;_2_models determining the links to be used for public transportation route construction;_3_models determining routes only;_4_models assigning frequencies to a set of routes;_5_two-stage models for constructing routes and then assigning frequencies;and_6_models for simultaneously determining routes and frequencies.Spacovic et al._1994_and Spacovic and Schonfeld_1994_proposed a matrix organization and classified each study according to design parameters examined,objectives anticipated,network geometry,and demand characteristics. Ceder and Israeli_1997_suggested broad categorizations for TRNDP models into passenger flow simulation and mathematical programming models.Russo_1998_adopted the same categorization and noted that mathematical programming models guarantee optimal transit network design but sacrifice the level of detail in passenger representation and design parameters, while simulation models address passenger behavior but use heuristic procedures obtaining a TRNDP solution.Ceder_2001_enhanced his earlier categorization by classifying TRNDP models into simulation,ideal network,and mathematical programming models.Finally,in a recent series of studies,Fan and Machemehl_2004,2006a,b_divided TRNDP approaches into practical approaches,analytical optimization models for idealized conditions,and metaheuristic procedures for practical problems.The TRNDP is an optimization problem where objectives are defined,its constraints are determined,and a methodology is selected and validated for obtaining an optimal solution.The TRNDP is described by the objectives of the public transportation network service to be achieved, the operational characteristics and environment under which the network will operate,and the methodological approach for obtaining the optimal network design.Based on this description of the TRNDP,we propose a three-layer structure for organizing TRNDP approaches_Objectives, Parameters,and Methodology_.Each layer includes one or more items that characterize each study.The“Objectives”layer incorporates the goals set when designing a public transportation system such as the minimization of the costs of the system or the maximization of the quality of services provided.The“Parameters”layer describes the operating environment and includes both the design variables expected to be derived for the transit network_route layouts,frequencies_as well as environmental and operational parameters affecting and constraining that network_for example,allowable frequencies,desired load factors,fleet availability,demand characteristics and patterns,and so on_.Finally,the“Methodology”layer covers the logical–mathematical framework and algorithmic tools necessary to formulate and solve the TRNDP.The proposed structure follows the basic concepts toward setting up a TRNDP:deciding upon the objectives, selecting the transit network items and characteristics to be designed,setting the necessary constraints for the operating environment,and formulating and solving the problem. TRNDP:ObjectivesPublic transportation serves a very important social role while attempting to do this at the lowest possible operating cost.Objectives for designing daily operations of a public transportation system should encompass both angles.The literature suggests that most studies actually focus on both the service and economic efficiency when designing such a system. Practical goals for the TRNDP can be briefly summarized as follows_Fielding1987;van Oudheudsen et al.1987;Black1995_:_1_user benefit maximization;_2_operator cost minimization;_3_total welfare maximization;_4_capacity maximization;_5_energy conservation—protection of the environment;and_6_individual parameter optimization.Mandl_1980_indicated that public transportation systems have different objectives to meet. He commented,“even a single objective problem is difficult to attack”_p.401_.Often,these objectives are controversial since cutbacks in operating costs may require reductions in the quality of services.Van Nes and Bovy_2000_pointed out that selected objectives influence the attractiveness and performance of a public transportation network.According to Ceder and Wilson_1986_,minimization of generalized cost or time or maximization of consumer surplus were the most common objectives selected when developing transit network design models. Berechman_1993_agreed that maximization of total welfare is the most suitable objective for designing a public transportation system while Van Nes and Bovy_2000_argued that the minimization of total user and system costs seem the most suit able and less complicatedobjective_compared to total welfare_,while profit maximization leads to nonattractive public transportation networks.As can be seen in Table1,most studies seek to optimize total welfare,which incorporates benefits to the user and to the er benefits may include travel,access and waiting cost minimization,minimization of transfers,and maximization of coverage,while benefits for the system are maximum utilization and quality of service,minimization of operating costs, maximization of profits,and minimization of the fleet size used.Most commonly,total welfare is represented by the minimization of user and system costs.Some studies address specific objectives from the user,theoperator,or the environmental perspective.Passenger convenience,the number of transfers, profit and capacity maximization,travel time minimization,and fuel consumption minimization are such objectives.These studies either attempt to simplify the complex objective functions needed to setup the TRNDP_Newell1979;Baaj and Mahmassani1991;Chakroborty and Dwivedi2002_,or investigate specific aspects of the problem,such as objectives_Delle Site and Fillipi2001_,and the solution methodology_Zhao and Zeng2006;Yu and Yang2006_.Total welfare is,in a sense,a compromise between objectives.Moreover,as reported by some researchers such as Baaj and Mahmassani_1991_,Bielli et al._2002_,Chackroborty and Dwivedi_2002_,and Chakroborty_2003_,transit network design is inherently a multiobjective problem.Multiobjective models for solving the TRNDP have been based on the calculation of indicators representing different objectives for the problem at hand,both from the user and operator perspectives,such as travel and waiting times_user_,and capacity and operating costs _operator_.In their multiobjective model for the TRNDP,Baaj and Majmassani_1991_relied on the planner’s judgment and experience for selecting the optimal public transportation network,based on a set of indicators.In contrast,Bielli et al._2002_and Chakroborty and Dwivedi_2002_,combined indicators into an overall,weighted sum value, which served as the criterion for determining the optimaltransit network.TRNDP:ParametersThere are multiple characteristics and design attributes to consider for a realistic representation of a public transportation network.These form the parameters for the TRNDP.Part of these parameters is the problem set of decision variables that define its layout and operational characteristics_frequencies,vehicle size,etc._.Another set of design parameters represent the operating environment_network structure,demand characters,and patterns_, operational strategies and rules,and available resources for the public transportation network. These form the constraints needed to formulate the TRNDP and are,a-priori fixed,decided upon or assumed.Decision VariablesMost common decision variables for the TRNDP are the routes and frequencies of the public transportation network_Table1_.Simplified early studies derived optimal route spacing between predetermined parallel or radial routes,along with optimal frequencies per route_Holroyd1967; Byrne and Vuchic1972;Byrne1975,1976;Kocur and Hendrickson1982;Vaughan1986_,while later models dealt with the development of optimal route layouts and frequency determination. Other studies,additionally,considered fares_Kocur and Hendrickson1982;Morlok and Viton 1984;Chang and Schonfeld1991;Chien and Spacovic2001_,zones_Tsao and Schonfeld1983; Chang and Schonfeld1993a_,stop locations_Black1979;Spacovic and Schonfeld1994; Spacovic et al.1994;Van Nes2003;Yu and Yang2006_and bus types_Delle Site and Filippi 2001_.Network StructureSome early studies focused on the design of systems in simplified radial_Byrne1975;Black 1979;Vaughan1986_,or rectangular grid road networks_Hurdle1973;Byrne and Vuchic1972; Tsao and Schonfeld1984_.However,most approaches since the1980s were either applied to realistic,irregular grid networks or the network structure was of no importance for the proposed model and therefore not specified at all.Demand PatternsDemand patterns describe the nature of the flows of passengers expected to be accommodated by the public transportation network and therefore dictate its structure.For example,transit trips from a number of origins_for example,stops in a neighborhood_to a single destination_such as a bus terminal in the CBD of a city_and vice-versa,are characterized as many-to-one_or one-tomany_transit demand patterns.These patterns are typically encountered in public transportation systems connecting CBDs with suburbs and imply a structure of radial orparallel routes ending at a single point;models for patterns of that type have been proposed by Byrne and Vuchic_1972_,Salzborn_1972_,Byrne_1975,1976_,Kocur and Hendrickson _1982_,Morlok and Viton_1984_,Chang and Schonfeld_1991,1993a_,Spacovic and Schonfeld_1994_,Spacovic et al._1994_,Van Nes_2003_,and Chien et al._2003_.On the other hand,many-to-many demand patterns correspond to flows between multiple origins and destinations within an urban area,suggesting that the public transportation network is expected to connect various points in an area.Demand CharacteristicsDemand can be characterized either as“fixed”_or“inelastic”_or“elastic”;the later meaning that demand is affected by the performance and services provided by the public transportation network.Lee and Vuchic_2005_distinguished between two types of elastic demand:_1_demand per mode affected by transportation services,with total demand for travel kept constant;and_2_total demand for travel varying as a result of the performance of the transportation system and its modes.Fan and Machemehl_2006b_noted that the complexity of the TRNDP has led researchers intoassuming fixed demand,despite its inherent elastic nature.However,since the early1980s, studies included aspects of elastic demand in modeling the TRNDP_Hasselstrom1981;Kocur and Hendrickson1982_.Van Nes et al._1988_applied a simultaneous distribution-modal split model based on transit deterrence for estimatingdemand for public transportation.In a series of studies,Chang and Schonfeld_1991,1993a,b_ and Spacovic et al._1994_estimated demand as a direct function of travel times and fares with respect to their elasticities,while Chien and Spacovic2001_,followed the same approach assuming that demand is additionally affected by headways,route spacing and fares.Finally, studies by Leblanc_1988_,Imam_1998_,Cipriani et al._2005_,Lee and Vuchic_2005_;and Fan and Machemehl_2006a_based demand estimation on mode choice models for estimating transit demand as a function of total demand for travel.中文译文：公交路线网络设计问题：回顾摘要：公共交通网络的有效设计让交通理论与实践成为众人关注的焦点，随之发展出了很多规划相关公交路线网络设计问题（TRNDP）的模型与方法。
毕业设计(论文)外文资料翻译
1、外文原文（复印件）2、外文资料翻译译文节能智能照明控制系统Sherif Matta and Syed Masud Mahmud, SeniorMember, IEEE Wayne State University, Detroit,Michigan 48202Sherif.Matta@,smahmud@摘要节约能源已成为当今最具挑战性的问题之一。
最浪费能源的来自低效利用的电能消耗的人工光源设备（灯具或灯泡）。
本文提出了一种通过把人工照明的强度控制到令人满意的水平，来节约电能，并且有详细设计步骤的系统。
在白天使用照明设备时，尽可能的节约。
当记录超过预设的照明方案时，引入改善日光采集和控制的调光系统。
设计原理是，如果它可以通过利用日光这样的一种方式，去控制百叶窗或窗帘。
否则，它使用的是人工建筑内部的光源。
光通量是通过控制百叶窗帘的开启角度来控制，同时，人工光源的强度的控制，通过控制脉冲宽度来调制（PWM）对直流灯的发电量或剪切AC灯泡的AC波。
该系统采用控制器区域网络（CAN），作为传感器和致动器通信用的介质。
该系统是模块化的，可用来跨越大型建筑物。
该设计的优点是，它为用户提供了一个单点操作，而这个正是用户所希望的光的亮度。
该控制器的功能是确定一种方法来满足所需的最小能量消耗光的量。
考虑的主要问题之一是系统组件的易于安装和低成本。
该系统显示出了显著节省的能源量，和在实际中实施的可行性。
关键词：智能光控系统，节能，光通量，百叶帘控制，控制器区域网络（CAN），光强度的控制一简介多年来，随着建筑物的数量和建筑物房间内的数量急剧增加，能源的浪费、低效光控制和照明分布难以管理。
此外，依靠用户对光的手动控制，来节省能源是不实际的。
很多技术和传感器最近已经向管理过多的能量消耗转变，例如在一定区域内的检测活动采用运动检测。
当有人进入房间时，自动转向灯为他们提供了便利。
他们通过在最后人员离开房间后不久关闭转向灯来减少照明能源的使用。
毕业设计外文翻译英文翻译英文原稿
Harmonic source identification and current separationin distribution systemsYong Zhao a，b，Jianhua Li a，Daozhi Xia a,*a Department of Electrical Engineering Xi’an Jiaotong University, 28 West Xianning Road, Xi’an, Shaanxi 710049, Chinab Fujian Electric Power Dispatch and Telecommunication Center, 264 Wusi Road, Fuzhou, Fujian, 350003, China AbstractTo effectively diminish harmonic distortions, the locations of harmonic sources have to be identified and their currents have to be separated from that absorbed by conventional linear loads connected to the same CCP. In this paper, based on the intrinsic difference between linear and nonlinear loads in their V –I characteristics and by utilizing a new simplified harmonic source model, a new principle for harmonic source identification and harmonic current separation is proposed. By using this method, not only the existence of harmonic source can be determined, but also the contributions of the harmonic source and the linear loads to harmonic voltage distortion can be distinguished. The detailed procedure based on least squares approximation is given. The effectiveness of the approach is illustrated by test results on a composite load.2004 Elsevier Ltd. All rights reserved.Keywords: Distribution system; Harmonic source identification; Harmonic current separation; Least squares approximation1. IntroductionHarmonic distortion has experienced a continuous increase in distribution systems owing to the growing use of nonlinear loads. Many studies have shown that harmonics may cause serious effects on power systems, communication systems, and various apparatus [1–3]. Harmonic voltages at each point on a distribution network are not only determined by the harmonic currents produced by harmonic sources (nonlinear loads), but also related to all linear loads (harmonic current sinks) as well as the structure and parameters of the network. To effectively evaluate and diminish the harmonic distortion in power systems, the locations of harmonic sources have to be identified and the responsibility of the distortion caused by related individual customers has to be separated.As to harmonic source identification, most commonly the negative harmonic power is considered as an essential evidence of existing harmonic source [4–7]. Several approaches aiming at evaluating the contribution of an individual customer can also be found in the literatures. Schemes based on power factor measurement to penalize the customer’s harmonic currents are discussed in Ref. [8]. However, it would be unfair to use economical penalization if we could not distinguish whether the measured harmonic current is from nonlinear load or from linear load.In fact, the intrinsic difference between linear and nonlinear loads lies in their V –I characteristics. Harmonic currents of a linear load are i n linear proportion to its supplyharmonic voltages of the same order 次, whereas the harmonic currents of a nonlinear load are complex nonlinear functions of its supply fundamental 基波and harmonic voltage components of all orders. To successfully identify and isolate harmonic source in an individual customer or several customers connected at same point in the network, the V –I characteristics should be involved and measurement of voltages and currents under several different supply conditions should be carried out.As the existing approaches based on measurements of voltage and current spectrum or harmonic power at a certain instant cannot reflect the V –I characteristics, they may not provide reliable information about the existence and contribution of harmonic sources, which has been substantiated by theoretical analysis or experimental researches [9,10].In this paper, to approximate the nonlinear characteristics and to facilitate the work in harmonic source identification and harmonic current separation, a new simplified harmonic source model is proposed. Then based on the difference between linear and nonlinear loads in their V –I characteristics, and by utilizing the harmonic source model, a new principle for harmonic source identification and harmonic current separation is presented. By using the method, not only the existence of harmonic source can be determined, but also the contributions of the harmonic sources and the linear loads can be separated. Detailed procedure of harmonic source identification and harmonic current separation based on least squares approximation is presented. Finally, test results on a composite load containing linear and nonlinear loads are given to illustrate the effectiveness of the approach.2. New principle for harmonic source identification and current separationConsider a composite load to be studied in a distribution system, which may represent an individual consumer or a group of customers supplied by a common feeder 支路in the system. To identify whether it contains any harmonic source and to separate the harmonic currents generated by the harmonic sources from that absorbed by conventional linear loads in the measured total harmonic currents of the composite load, the following assumptions are made.(a) The supply voltage and the load currents are both periodical waveforms withperiod T; so that they can be expressed by Fourier series as1()s i n (2)h h h v t ht T πθ∞==+ (1)1()sin(2)h h h i t ht πφ∞==+The fundamental frequency and harmonic components can further be presented bycorresponding phasorshr hi h h hr hi h hV jV V I jI I θφ+=∠+=∠ , 1,2,3,...,h n = (2)(b) During the period of identification, the composite load is stationary, i.e. both its composition and circuit parameters of all individual loads keep unchanged.Under the above assumptions, the relationship between the total harmonic currents of the harmonic sources(denoted by subscript N) in the composite load and the supply voltage, i.e. the V –I characteristics, can be described by the following nonlinear equation ()()()N i t f v t = (3)and can also be represented in terms of phasors as()()122122,,,...,,,,,,...,,Nhr r i nr ni Nh Nhi r inr ni I V V V V V I I V V V V V ⎡⎤=⎢⎥⎣⎦ 2,3,...,h n = (4)Note that in Eq. (4), the initial time (reference time) of the voltage waveform has been properly selected such that the phase angle u1 becomes 0 and 10i V =, 11r V V =in Eq. (2)for simplicity.The V –I characteristics of the linear part (denote by subscript L) of the composite load can be represented by its equivalent harmonic admittance Lh Lh Lh Y G jB =+, and the total harmonic currents absorbed by the linear part can be described as,Lhr LhLh hr Lh Lhi LhLh hi I G B V I I B G V -⎡⎤⎡⎤⎡⎤==⎢⎥⎢⎥⎢⎥⎣⎦⎣⎦⎣⎦2,3,...,h n = (5)From Eqs. (4) and (5), the whole harmonic currents absorbed by the composite load can be expressed as()()122122,,,...,,,,,,...,,hr Lhr Nhr r i nr ni h hi Lhi Nhi r inr ni I I I V V V V V I I I I V V V V V ⎡⎤⎡⎤⎡⎤==-⎢⎥⎢⎥⎢⎥⎣⎦⎣⎦⎣⎦ 2,3,...,h n = (6)As the V –I characteristics of harmonic source are nonlinear, Eq. (6) can neither be directly used for harmonic source identification nor for harmonic current separation. To facilitate the work in practice, simplified methods should be involved. The common practice in harmonic studies is to represent nonlinear loads by means of current harmonic sources or equivalent Norton models [11,12]. However, these models are not of enough precision and new simplified model is needed.From the engineering point of view, the variations of hr V and hi V ; ordinarily fall into^3% bound of the rated bus voltage, while the change of V1 is usually less than ^5%. Within such a range of supply voltages, the following simplified linear relation is used in this paper to approximate the harmonic source characteristics, Eq. (4)112222112322,ho h h r r h i i hnr nr hni ni Nh ho h h r r h i i hnr nr hni ni a a V a V a V a V a V I b b V b V b V b V b V ++++++⎡⎤=⎢⎥++++++⎣⎦2,3,...,h n = (7)这个地方不知道是不是原文写错？23h r r b V 其他的都是2The precision and superiority of this simplified model will be illustrated in Section 4 by test results on several kinds of typical harmonic sources.The total harmonic current (Eq. (6)) then becomes112222112222,2,3,...,Lh Lh hr ho h h r r h i i hnr nr hni ni h Lh Lh hi ho h h r r h i i hnr nr hni ni G B V a a V a V a V a V a V I B G V b b V b V b V b V b V h n-++++++⎡⎤⎡⎤⎡⎤=-⎢⎥⎢⎥⎢⎥++++++⎣⎦⎣⎦⎣⎦= (8)It can be seen from the above equations that the harmonic currents of the harmonic sources (nonlinear loads) and the linear loads differ from each other intrinsically in their V –I characteristics. The harmonic current component drawn by the linear loads is uniquely determined by the harmonic voltage component with same order in the supply voltage. On the other hand, the harmonic current component of the nonlinear loads contains not only a term caused by the same order harmonic voltage but also a constant term and the terms caused by fundamental and harmonic voltages of all other orders. This property will be used for identifying the existence of harmonic source sin composite load.As the test results shown in Section 4 demonstrate that the summation of the constant term and the component related to fundamental frequency voltage in the harmonic current of nonlinear loads is dominant whereas other components are negligible, further approximation for Eq. (7) can be made as follows.Let112'012()()nh h hkr kr hki ki k k h Nhnh h hkr kr hki kik k h a a V a V a V I b b V b V b V =≠=≠⎡⎤+++⎢⎥⎢⎥=⎢⎥⎢⎥+++⎢⎥⎢⎥⎣⎦∑∑ hhr hhi hr Nhhhr hhi hi a a V I b b V ⎡⎤⎡⎤''=⎢⎥⎢⎥⎣⎦⎣⎦hhrhhihr Lh Lh Nh hhrhhi hi a a V I I I b b V ''⎡⎤⎡⎤'''=-=⎢⎥⎢⎥''⎣⎦⎣⎦,2,3,...,hhr hhiLh Lh hhrhhi hhr hhi Lh Lh hhr hhi a a G B a a h n b b B G b b ''-⎡⎤⎡⎤⎡⎤=-=⎢⎥⎢⎥⎢⎥''⎣⎦⎣⎦⎣⎦The total harmonic current of the composite load becomes112012(),()2,3,...,nh h hkr kr hki ki k k hhhrhhi hr h Lh NhLhNh n hhrhhi hi h h hkr kr hki kik k h a a V a V a V a a V I I I I I b b V b b V b V b V h n=≠=≠⎡⎤+++⎢⎥⎢⎥''⎡⎤⎡⎤''=-=-=-⎢⎥⎢⎥⎢⎥''⎣⎦⎣⎦⎢⎥+++⎢⎥⎢⎥⎣⎦=∑∑ (9)By neglecting ''Nh I in the harmonic current of nonlinear load and adding it to the harmonic current of linear load, 'Nh I can then be deemed as harmonic current of thenonlinear load while ''Lh I can be taken as harmonic current of the linear load. ''Nh I =0 means the composite load contains no harmonic sources, while ''0NhI ≠signify that harmonic sources may exist in this composite load. As the neglected term ''Nh I is not dominant, it is obviousthat this simplification does not make significant error on the total harmonic current of nonlinear load. However, it makes the possibility or the harmonic source identification and current separation.3. Identification procedureIn order to identify the existence of harmonic sources in a composite load, the parameters in Eq. (9) should be determined primarily, i.e.[]0122hr h h h rh i hhr hhihnr hni C a a a a a a a a ''= []0122hi h h h rh i hhrhhihnr hni C b b b b b b b b ''=For this purpose, measurement of different supply voltages and corresponding harmoniccurrents of the composite load should be repeatedly performed several times in some short period while keeping the composite load stationary. The change of supply voltage can for example be obtained by switching in or out some shunt capacitors, disconnecting a parallel transformer or changing the tap position of transformers with OLTC. Then, the least squares approach can be used to estimate the parameters by the measured voltages and currents. The identification procedure will be explained as follows.(1) Perform the test for m （2m n ≥）times to get measured fundamental frequency andharmonic voltage and current phasors ()()k k h h V θ∠,()()k k hh I φ∠,()1,2,,,1,2,,k m h n == .(2) For 1,2,,k n = ，transfer the phasors corresponding to zero fundamental voltage phase angle ()1(0)k θ=and change them into orthogonal components, i.e.()()11kkr V V = ()10ki V =()()()()()()()()()()11cos sin kkkkk kkkhr h h hihhV V h V V h θθθθ=-=-()()()()()()()()()()11cos sin k kkkk kkkhrhhhihhI I h I I h φθφθ=-=-,2,3,...,h n =(3)Let()()()()()()()()1221Tk k k k k k k k r i hr hi nr ni VV V V V V V V ⎡⎤=⎣⎦ ,()1,2,,k m = ()()()12Tm X V V V ⎡⎤=⎣⎦ ()()()12T m hr hr hr hrW I I I ⎡⎤=⎣⎦()()()12Tm hi hi hihi W I I I ⎡⎤=⎣⎦ Minimize ()()()211hr mk hr k I C V=-∑ and ()()()211him k hi k IC V=-∑, and determine the parametershr C and hi C by least squares approach as [13]:()()11T T hr hr T T hi hiC X X X W C X X X W --== (10)(4) By using Eq. (9), calculate I0Lh; I0Nh with the obtained Chr and Chi; then the existence of harmonic source is identified and the harmonic current is separated.It can be seen that in the course of model construction, harmonic source identification and harmonic current separation, m times changing of supply system operating condition and measuring of harmonic voltage and currents are needed. More accurate the model, more manipulations are necessary.To compromise the needed times of the switching operations and the accuracy of the results, the proposed model for the nonlinear load (Eq. (7)) and the composite load (Eq. (9)) can be further simplified by only considering the dominant terms in Eq. (7), i.e.01111,Nhr h h hhr hhi hr Nh Nhi ho h hhrhhi hi I a a V a a V I I b b V b b V +⎡⎤⎡⎤⎡⎤⎡⎤==+⎢⎥⎢⎥⎢⎥⎢⎥+⎣⎦⎣⎦⎣⎦⎣⎦2,3,,h n = (11) 01111h h Nh ho h a a V I b b V +⎡⎤'=⎢⎥+⎣⎦01111,hr hhrhhi hr h h h LhNh hi hhr hhihi ho h I a a V a a V I I I I b b V b b V ''+⎡⎤⎡⎤⎡⎤⎡⎤''==-=-⎢⎥⎢⎥⎢⎥⎢⎥''+⎣⎦⎣⎦⎣⎦⎣⎦2,3,,h n = (12) In this case, part equations in the previous procedure should be changed as follows[]01hr h h hhrhhi C a a a a ''= []01hi h h hhrhhiC b b b b ''= ()()()1Tk k k hr hi V V V ⎡⎤=⎣⎦ Similarly, 'Nh I and 'Lh I can still be taken as the harmonic current caused by thenonlinear load and the linear load, respectively.4. Experimental validation4.1. Model accuracyTo demonstrate the validity of the proposed harmonic source models, simulations are performed on the following three kind of typical nonlinear loads: a three-phase six-pulse rectifier, a single-phase capacitor-filtered rectifier and an acarc furnace under stationary operating condition.Diagrams of the three-phase six-pulse rectifier and the single-phase capacitor-filtered rectifier are shown in Figs. 1 and 2 [14,15], respectively, the V –I characteristic of the arc furnace is simplified as shown in Fig. 3 [16].The harmonic currents used in the simulation test are precisely calculated from their mathematical model. As to the supply voltage, VekT1 is assumed to be uniformly distributed between 0.95 and 1.05, VekThr and VekThi ek 1; 2;…;m T are uniformly distributed between20.03 and 0.03 with base voltage 10 kV and base power 1 MVFig. 1. Diagram of three-phase six-pulse rectifier.Fig. 2. Diagram of single-phase capacitor-filtered rectifierFig. 3. Approximate V –I characteristics of arc furnace.Three different models including the harmonic current source (constant current) model, the Norton model and the proposed simplified model are simulated and estimated by the least squares approach for comparison.For the three-phase six-pulse rectifier with fundamental currentI=1.7621; the1 parameters in the simplified model for fifth and seventh harmonic currents are listed in Table 1.To compare the accuracy of the three different models, the mean and standard deviations of the errors on Ihr; Ihi and Ih between estimated value and the simulated actual value are calculated for each model. The error comparison of the three models on the three-phase six-pulse rectifier is shown in Table 2, where mhr; mhi and mha denote the mean, and shr; shi and sha represent the standard deviations. Note that I1 and _Ih in Table 2are the current values caused by rated pure sinusoidal supply voltage.Error comparisons on the single-phase capacitor-filtered rectifier and the arc furnace load are listed in Table 3 and 4, respectively.It can be seen from the above test results that the accuracy of the proposed model is different for different nonlinear loads, while for a certain load, the accuracy will decrease as the harmonic order increase. However, the proposed model is always more accurate than other two models.It can also be seen from Table 1 that the componenta50 t a51V1 and b50 t b51V1 are around 20:0074 t0:3939 0:3865 and 0:0263 t 0:0623 0:0886 while the componenta55V5r and b55V5i will not exceed 0:2676 ￡0:03 0:008 and 0:9675 ￡0:003 0:029; respectively. The result shows that the fifth harmonic current caused by the summation of constant term and the fundamental voltage is about 10 times of that caused by harmonic voltage with same order, so that the formal is dominant in the harmonic current for the three-phase six-pulse rectifier. The same situation exists for other harmonic orders and other nonlinear loads.4.2. Effectiveness of harmonic source identification and current separationTo show the effectiveness of the proposed harmonic source identification method, simulations are performed on a composite load containing linear load (30%) and nonlinear loads with three-phase six-pulse rectifier (30%),single-phase capacitor-filtered rectifier (20%) and ac arc furnace load (20%).For simplicity, only the errors of third order harmonic current of the linear and nonlinear loads are listed in Table 5, where IN3 denotes the third order harmonic current corresponding to rated pure sinusoidal supply voltage; mN3r ;mN3i;mN3a and mL3r ;mL3i;mL3a are error means of IN3r ; IN3i; IN3 and IL3r ; IL3i; IL3 between the simulated actual value and the estimated value;sN3r ;sN3i;sN3a and sL3r ;sL3i;sL3a are standard deviations.Table 2Table 3It can be seen from Table 5 that the current errors of linear load are less than that of nonlinear loads. This is because the errors of nonlinear load currents are due to both the model error and neglecting the components related to harmonic voltages of the same order, whereas only the later components introduce errors to the linear load currents. Moreover, it can be found that more precise the composite load model is, less error is introduced. However, even by using the very simple model (12), the existence of harmonic sources can be correctly identified and the harmonic current of linear and nonlinear loads can be effectively separated. Table 4Error comparison on the arc furnaceTable 55. ConclusionsIn this paper, from an engineering point of view, firstly anew linear model is presented for representing harmonic sources. On the basis of the intrinsic difference between linear and nonlinear loads in their V –I characteristics, and by using the proposed harmonic source model, a new concise principle for identifying harmonic sources and separating harmonic source currents from that of linear loads is proposed. The detailed modeling and identification procedure is also developed based on the least squares approximation approach. Test results on several kinds of typical harmonic sources reveal that the simplified model is of sufficient precision, and is superior to other existing models. The effectiveness of the harmonic source identification approach is illustrated using a composite nonlinear load.AcknowledgementsThe authors wish to acknowledge the financial support by the National Natural Science Foundation of China for this project, under the Research Program Grant No.59737140. 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毕业论文英文翻译及原文封面【范本模板】
毕业设计(论文)英文翻译及原文课题名称：基于Flexsim的城市生活垃圾收运路径仿真研究学院 : 旭日工商管理学院专业：物流管理姓名：董继超 __ 学号：080750517指导教师：贾永基二0一一年十二月六日英文翻译文章用于餐厅垃圾回收过程中的堆肥和热水解之间的环境负担比较1. 环境科学与工程系，清华大学，北京100084，中国摘要:近年来，在中国政府积极地态度和一些有效的餐馆垃圾管理下，餐馆垃圾回收有了显著的发展.为了评价餐馆垃圾回收对环境的影响，生命周期评估（LCA）比较了两个回收过程—堆肥和热水解- 估计能源消耗和污染物排放。
结果表明,有效的过程,在每个影响的类别不同，进行了评估，堆肥对全球变暖有更大的影响,达到了337.7公斤的二氧化碳相当量/公斤。
相比之下，由于能耗大，热水解中对生态毒性施加的影响更大。
但是，总的来说，热水解对环境的影响相对于堆肥来说只有65％，减少了对其他三个的影响：酸雨，富氧化和全球变暖。
显然，热水解是一种很有效的减少环境压力的回收方法.关键词：堆肥；热水解；环境负担;餐厅垃圾;生命周期评估1．引言随着中国加速城市化的可持续发展和人民生活水平的提高,餐饮垃圾已经变成都市固体废物的重要组成部分,约占50—70％.在北京，餐厅垃圾的日常产量已达1200吨.餐厅垃圾，可以诱发腐烂废物收集和运输，降低效率储存，输送,切碎和分离；引进在焚化过程中的水分和Cl；导致有气味的化合物的排放；从垃圾填埋场渗滤液的质量产生不利影响，已成为严重的环境问题。
在北京餐厅垃圾中的37％是都市固体废物(MSW），其合适的管理方法已成为在过去十年中最活跃的辩论问题。
许多技术，如崩溃，堆肥，利用来对待餐厅垃圾发酵等。
然而，在个别技术研究越来越感兴趣，目前已经在研究.根据北京餐厅垃圾对环境的看法做出综合评价。
在这项研究中，根据实际设施的运行参数，我们选择了两个典型的回收方法，在系统中以一吨餐厅的垃圾作为一个单位来考虑。