《毕业设计》
文献翻译
院系：电子电气工程学院学号：021309208
姓名：吴骁奕
指导教师：曾国辉
完成时间：2013/2/15
文献翻译
021309208 吴骁奕
A Flexible LED Driver for Automotive Lighting Applications: IC Design and E xperimental Characterization
一个灵活的LED驱动汽车照明应用:集成电路设计和实验特征
Abstract—This letter presents a smart driver for LEDs, particularly
摘要：这文章提出了一个智能驱动发光二极管，
for automotive lighting applications, which avoid ringing
尤其是用于避免振荡和超调现象的汽车照明应用上，
and overshoot phenomena. To this aim, advanced Soft Start and
为了这个目的，在芯片上集成了优化软启动和电流升降控制技术。Current Slope Control techniques are integrated on-chip. This letter
这篇文章讨论了设计于集合于高电压的互补金属氧化半导体上的驱动技术，
discusses the driver design integrating in high voltage CMOS
technology, the digital circuitry for programming and electronic
用于编程和电子控制单元连接的数字电路以及功率元件提高到10瓦特。
control units interfacing, and the power devices up to 10W. Experimental
同时也展示了不同功率等级使用的发光二极管和与不同类型的连接时的实验特征。
characterizations with LEDs of different power levels and
with different types of connections are showed. The smart driver
这个智能的驱动适用于可调节的温度和电压需求。
sustains automotive temperature and voltage requirements; moreover
此外，它有很高的功率效率，它是可编程的，还可以配置用于线性的调节器。
it has high power efficiency, it is programmable, and can be
configured to work as a linear regulator (for low current LEDs) or
in switch mode (for higher power LEDs).
（用于弱电流发光二极管）或转换模式（用于高功率发光二极管）IndexTerms—Automotive electronics, high voltage (HV)CMOS,
integrated circuit (IC), LED driver.
关键词—汽车用电子设备，高电压互补金属氧化物半导体，集成电路
LED驱动
I. INTRODUCTION
1：介绍
IN the last few years LED technology experienced a very fast
在过去的几年中，发光二极管技术在汽车照明应用中替代普通灯泡经历了一个非常快速的进步时代，
and important growth, superseding the bulb technology in
automotive lighting applications [1]. To achieve the harsh requirement
of CO2 emission and reduce the fuel consumption,
car manufacturer must reduce the total power consumption. The
为了实现了严格的二氧化碳排放要求和降低了燃料的消耗,
汽车制造商必须减少总的功率消耗。
adoption of LEDs in place of bulbs permits to have about five
times less power consumption at equal output lighting intensity.
采用发光二极管代替灯泡在同等输出功率照明强度下损耗将降低五倍。
LEDs have reached quality and reliability factors that permit
their use in automotive harsh environment and in addition
发光二极管已达到质量和可靠性因素,可保证他们可使用在汽车的严
酷环境下并且他们的成本是降低的。
their cost is decreasing. However, LEDs are pretty difficult to
事实上，发光二极管是很难驱动，因此相比较普通灯泡，发光二极管驱动要求更多的技巧和控制功能。
drive and therefore LED-drivers require many tricks and control
functions compared to bulb drivers. Moreover, automotive
而且，汽车应用程序需要紧凑和低成本的解决方案,灵活
足够的数字电子控制单元界面，
applications require compact and low-cost solutions, flexible
enough to be interfaced to digital electronic control units (ECU)
and to cope with different wiring configurations and relevant
同时需要应付不同的布线配置和相关拓展。
parasitics [2]. Automotive lighting systems should be also robust
汽车照明系统也应该对电磁干扰(EMI)和超温、过流以及过电压现象有应变能力。
with respect to electromagnetic interference (EMI) and
to overtemperature, overcurrent, and overvoltage phenomena,
such as those due to ringing effects generated by resonance of
例如那些由于激振效应所产生的共振的线电感和连接器电容。
wire inductance and connector capacitance. Usually, in car environment
通常,在汽车环境中，几米长电线使用,就会生成强烈振荡。
few meters long wires are used, generating dumped
oscillations. Such oscillations and the associated overcurrent
and overvoltage levels reduce the LED life time and its efficiency
这种振荡和与之相关的过电流和过电压会降低发光二极管寿命及其效率。
[3]. To avoid or limit these effects the LED cannot be
driven by a mechanical relay but a smart driver is required to
control the slope of the LED current during transient, keeping it
为了避免或限制这些影响发光二极管不能由一个机械继电器控制但智能的驱动被要求需要在瞬态控制LED电流的斜率，以保持它在电线
的特征频率以下。
below the characteristic frequency of the wire. A compact and
efficient LED driver is needed, overcoming the above issues and
featuring a high flexibility to face different LED power levels,
一个紧凑和高效的LED驱动程序是必要的,是为了克服上述问题和具有高灵活性，去面对不同的发光二极管功率级别，连接拓扑和电线寄生。
connections topology, and wiring parasitics. Hereafter, Section
此后，在第二部分，分析了振荡和电磁干扰在放光二极管驱动中的影响。
II analyzes ringing and EMI problems in LED driving. Section
III presents the design of the new LED smart driver focusing on
第三部分介绍了一款新设计的智能发光二极管驱动的显著特征。
its distinguishing features. Section IV presents its experimental
第四部分介绍了发光二极管在不同功率等级下的实验特征，从几十毫瓦特
characterization with LEDs of different power levels, from tens
of milliwatts to several watts, used stand-alone, or connected in
到几瓦特在独立或几个连接下的状态。
strings. Temperature and voltage range operating conditions are
温度和电压等级的工作条件也被测量判断。
also measured. Conclusions are drawn in Section V.
第五部分将引出结论。
II. RINGING AND EMI PROBLEMS IN LED DRIVING
二.振荡和电磁干扰在发光二极管驱动中的影响
At state-of-the-art LED, driving is implemented using lowdrop
out linear regulators, which are limited to LEDs of few tens
of milliamperes, or more power-efficient switching solutions at
higher current levels
在最开始的LED,开车是使用低输出线性稳压器,仅限于几十毫安级的发光二极管,或更省电转换解决方案用在更高的电流水平。
[3]–[10]. However, a compact solution integrating
然而,一个紧凑的集成解决方案在一个单芯片数字ECU接口,
on a single chip a digital ECU interface, a low-power
configurable logic core, a power part able to work in linear mode
or switching one, as well as advanced techniques such as Soft
Start and Current Slope Control, has not been proposed yet in
一个低功耗可配置的逻辑核心,电源部分能够工作在线性模式或转换它,以及先进的技术,如软开始和电流升降调节，还没有在文献中被提出。
the literature. The main difficulties in the design of a universal
设计一个足够的灵活的发光二极管驱动应用在不同的接线配置
最大的难题是振荡和电磁干扰问题。
LED driver, flexible enough to be applied to different wiring
configurations, are the ringing and EMI issues. These problems
这些问题取决于环境因素和寄生组件，这些因素很难去假设和模仿。depend on environmental and parasitic components that are difficult
to predict and simulate.While bulbs are easily modeled as
而电灯泡却很容易模仿因为它有线性的正温度系数并且寄生成分对它的影响比较小。
linear positive temperature coefficient (PTC) resistors, and are
less sensitive to parasitic components, a LED is a special diode
发光二极管是一种特殊的二极管，它满足肖克利指数电流-电压法。and follows the Shockley exponential I–V law. A very small
fluctuation on the voltage across the LED can generate a very
一个很小的电压起伏通过发光二极管可能引起一个很大的电流变化
影响。
high variation on its current affecting, as proved in [3], both efficiency
经证明，效率和照明设备的寿命都将被影响。
and life time and creating lighting disturbs. This behavior
如果发光二极管没有恰当的被驱动的话这个行为会导致振荡和高强度的电流尖脉冲。
can generate ringing and high current spikes if the LED is not properly driven. By the same token, a bulb-designed driver, as
出于同样的原因，灯泡的驱动，正如10-12中说的，不能被直接用于驱动发光二极管。
shown in [10]–[12], cannot be directly used to drive efficiently
LEDs. This is particularly true when the LED and the driver are
这一点是完全正确的当发光二极管和驱动在汽车连接中被几米的电缆分割的时候。
separated by a few meter cables as in automotive connections.
In this case, the wiring parasitics can generate ringing and EMI.
出于这个原因，电线的寄生将引起振荡和电磁干扰。
A comparison based on experimental measurements, between
一个在二瓦特的灯泡和0.1瓦特的连着很短的线（大概10厘米长）发光二极管的比较实验中显示在图1和图2中。
a 2-W bul
b lamp and a 0.1-W LED turn-on transient with very
short wire (about 10 cm long) and with very long wire (about
3m long) is shown, respectively, in Figs. 1 and 2. A simple
relay is used as a switch to highlight the different behavior
一个简单的继电器被用来切换到这些负载不同的状态。
of those loads. Those pictures show the necessity of using a
这些图片展示了使用一个设计良好的LED驱动从而避免寄生电路的重要性。
well-designed driver for LEDs, to avoid unwanted effects due
to wiring parasitics. In fact, the behavior of the current in the
事实上，灯泡的电流状态不随着线的长度而变化。[从图1a图2a可以看出]
bulb does not change significantly with the wire length [see
Figs. 1(a) and 2(a)] while the transient of the current in the
而发光二极管的瞬间电流缺有显著的差异。[从图1b和2b可以看出] LED shows significant differences [see Figs. 1(b) and 2(b)]. To
overcome this issue we propose a compact solution, integrating
为了解决这个问题我们计划了一个简洁的方案：
in 0.35-μmHVCMOStechnology the digital circuitry for driver
interfacing/configuration and power devices up to 10W, with
采用高压CMOS技术数字电路的驱动程序，接口/配置和功率设备提高到10 瓦特
HV protection up to 55V. The LED driver can be interfaced to
同时高压保护提高到55伏特。LED驱动可以被显示到数字电子控制单元，
digital ECU [13]–[15] and is able to cope with different wiring
从而它可以处理各种长度的电线配置和寄生电路。
configurations some meters long and their parasitics [2], and to
使其适应作为线性稳压器和开关的表现，取决于编程的精度。adapt its behavior working as linear regulator or as a switching
one, depending on a programmable threshold.
III. FLEXIBLE LED DRIVER IC
三. 灵活的发光二极管驱动集成电路
With respect to the bulb lamp driver shown in [11], [12] the
关于指示灯驱动器了，智能LED驱动必须满足严酷的汽车环境约束。smart LED driver needs to fulfill the same harsh automotive environment constraints, as well as more power demanding loads,
同时也要满足更多的功率负载需求用于串联和并联配置下的发光二极管。
as series and parallel configuration of LEDs. Low power LEDs,
like those employed in the car dashboard, absorbing 30–50mW,
像那些30-50毫瓦的用于汽车仪表盘的低功率发光二极管，包括那些排列在一起的总功率到10瓦特的发光二极管或灯泡，能被提议的设计驱动。
as well as arrays of power LEDs or lamps up to 10W, can be
driven properly by the proposed design.
图1.（a）灯泡（b）发光二极管在没有任何电流电压
控制的10厘米电缆下状态
图2 （a）灯泡（b）发光二极管在没有任何电流电压控制3厘米电缆下状态
图3. 方案一允许的负载配置,加强了布线寄生现象, 发光二极管,和串联的电池中的开关。
图4.LED驱动集成电路的体系结构和详细电路
The driving of LEDs has required the implementation of specific techniques to limit the undesired effects of wiring parasitics,
发光二极管的驱动要求实施特定的技术来限制布线寄生现象带来的不良影响。
such as ringing andconsequent overshoots and undershoots
如振荡和随之引起的超调量和脉冲信号。
.In Fig. 3, the scheme of the wiring parasitic and of a possible connection between
the driver and the load is shown: the output pin of the driver,
在图三中，该计划的布线寄生和可能的在驱动和负载的连接中显示:输出的驱动程序，其功能可以用一个简单的开关描述，是连接发光二极管，并且和汽车的
whose functionality can be represented by a simple switch to
the ground, is connected to a LED, in series with the car battery
and another switch, controlled by the user through a button or
电池和另外一个开关连接，而用户通过一个按钮或点火钥匙来控制它。
the ignition key. The basic scheme of the flexible LED driver
is shown in Fig. 4, together with circuit details of the operational
这个灵活的发光二极管驱动基本方案以及电路详细的步骤和跨导放大器块如图四所示。
transconductance amplifier (OTA) block: the architecture
这个设计基于一个
is based on a voltage regulation loop inserted inside a linear loop
providing the current control capability.
插入在一个线性循环的电压调节回路以提供当前的控制能力。
The voltage regulationloop forces the output on a reference voltage, Vref , when 电压调节回路控制输出的是参考电压当低压测主电源开关串联二极管以提供反极性的容量给装置，是开启了。
the low side main power switch (power MOS in Fig. 4), in series with
the Diode that provides reverse polarity capability to the device,
is turn ON. The LED driver has been integrated as hard macrocell
LED驱动程序已经被集成在一个复杂的大容量的电池汽车控制单元集成电路中
in a complex automotive control unit IC, implemented in
Austria micro systems (AMS) 0.35 μm CMOS technology. Fig 5
被用在AMS0.35UM的互补金属氧化物半导体技术中。从图5中可以看出，
shows the layout and the photo of the whole control unit IC,
布局和图片的整个控制单元集成在电路中，使得发光二极管驱动电子电路增强。
highlighting the LED driver circuit, and particularly the power
MOS and its protection diode in Fig. 4, which occupy most of
the LED driver area.
特别的在图四中的MOS材料和二极管的保护，占绝了绝大部分的发光二极管驱动电路。
By regulating the output voltage on a reference level the state
of the load and of the power switch can be easily detected.
通过调节输出电压在一个参考电平状态的负载和电源开关可以很容易地被检测到。
When the LED is ON (user switch and power switch in Fig. 3
当发光二极管打开，（用开关或者图3的电源开关都可以使运转）both enabled), the regulation loop is activated and the output
调节回路是激活的，输出电压是控制为参考电压的。
Vo is forced on the reference voltage, Vref . If the user switch
同时强制发光二极管也关闭，如果关闭开关,因此发光二极管也关闭is OFF, and hence also the LED is OFF, the output pin of the
driver is pulled down even when the power switch is OFF, by
输出引线驱动被损坏甚至电源总开关也关掉，意味着编的程序没有应
变能力。
means of a programmable resistive path to ground. That path
is highly resistive to limit to very low value the current flowing
through the LED. Finally, if the user switch is ON but the
这条道路的高电阻是用来限制非常低的电流来通过发光二极管，如果用户开关打开但电源开关关闭，那么输出电压将强迫输出为电源的额定电压。
power switch is forced OFF, then the output Vo is pulled up to
the battery voltage, Vbatt , and the LED is OFF since no noticeable
发光二极管也将关闭直到没有明显的电流通过。
current is flowing. Summarizing, depending on the status
of the switch devices in Fig. 3, the output voltage Vo can be
pulled down to ground, or pulled up to Vbatt or forced to Vref .
根据不同开关设备的状态，如图3所示,输出电压可以接地,或者强迫为电源的额定电压。
A comparator can reveal the status of the driver and also potential
overvoltage conditions by comparing the output voltage
to proper thresholds. Similarly overcurrent and overtemperature
一个比较器可以显示驱的状态和通过比较输出电压合适的阈值看出潜在的过压条件。
phenomena can be detected by comparing the measured current
and temperature values (through an on-chip temperature sensor)
with proper thresholds. All reference and threshold levels are
同样的过电流和超温现象是可以探测到的测量的电流和温度的值(通过一个芯片上的温度传感器)和适当的阈值比较。
internally generated by a digital-programmable band-gap unit.
所有的引用和阈值水平是由内部产生的数字通过可编程的带隙装置。The measurements shown in this letter are obtained with a Vref
这篇文章中的测量值是通过额定电压获得，1.2伏特。
of 1.2V. The detected driver and load status are used by the
internal logic as feedback signals to properly drive the power
MOS in Fig. 4, acting as linear regulator or ON–OFF switch,
检测到的驱动和负载状态使用内部逻辑作为反馈信号正确驱动动力在图四中的金属氧化物半导体,是作为线性调节器或开关
and implementing advanced Soft Start or Current Slope Control techniques.
和实施先进的软启动或电流升降控制技术
The working mode of the LED driver, as linear regulator or
ON–OFF switch, is determined by the user by proper configuring
the Current level Iref in Fig. 4. The MOSMA mirrors a small
工作模式的LED驱动,线性调节器或通断开关,是由用户通过适当的配置在图4按图四的电流是水平。
fraction of the power MOS output current and, through the HV
and Low-Voltage (LV) current mirrors in Fig. 4,
MOSMA反射小部分功率从MOS输出电流,如图四通过高压和低压(LV)电流反射镜镜，
compares it to the Iref current value (generated through on-chip band-gap circuit).
比较其当前值(通过芯片上的带隙电路生成Iref)。
The HV PMOS current mirror is connected to the output
voltage, which is up to 12V, while the LV PMOS current mirror
is connected to Vdd = 3.3V. The difference between Imir and
高压PMOS的电流反射连接到输出电压提高到12伏特,而低压PMOS电流反射连接到Vdd是3伏特。
Iref drives the gate of MOS MB : if Imir is lower than Iref , then
Imir和Iref之间的在MOS驱动上的区别是：如果Imir低于Irel，那么MB是关闭的
MB is OFF and the power MOS, driven by the OTA in Fig. 4,
并且MOS的能量是由如图四中的OTA驱动的，通过线性的电流调节器。acts as a linear current regulator. Otherwise, MB is ON and the
反之，如果MB是打开的而电流环路控制开关关闭，那么MOS MB将会被
强制关闭。
current loop control switches to the OFF state the power MOS.
The MOS MB can be forced back in OFF state, and hence the
同时强制电源MOS起作用，如图四用来进行逻辑控制。
powerMOS reactived, by the control logic in Fig. 4. The control
logic determines the times Ton and Toff when MB is OFF (i.e.,
这个控制逻辑决定什么时候开什么时候关分别当MB关掉的时候（MOS 开着）
power MOS is ON) or MB is ON (i.e., power MOS is OFF), respectively.
或者MB开着（MOS关闭）
In this case, the driver is working in ON–OFF switch
因此，这个驱动工作在关或开的模式为了满足控制逻辑不停的变换开关。
mode with duty cycle and frequency depending on the Ton and
Toff times set by the control logic.
Summarizing, in linear regulator mode Iref is configured so
that the current loop control is activated only for output currents
of several amperes, much higher than the operating load currents
总结,在线性调节器模式Iref是如此配置的为了电流环路控制输出电流只有安培。
foreseen for this LED driver (see Section IV). In linear mode,
远高于操作负载电流的LED驱动程序(见第四部分)。在线性莫模型中，Iref acts as a protection threshold: if Imir is over Iref then MB is
Iref担当着一个保护的临界值：当Imir超过了Iref，那么MB会打开，电源MOS会关闭。
switched ON and the power MOS is switched OFF.
In ON/OFF switching mode, Iref is configured at levels lower
在开/关模式下，Iref是按从低到高电流等级配置的。
than normal operating currents: the power MOS is no directly
driven by the OTA and the combined action of the current loop
control and of the control logic on the MOS MB determines the
Ton and Toff periods (and hence the switching duty cycle and
frequency) of the power MOS. To be noted that in switching
电源MOS没有直接被OTA和联合作用的电流环路控制。同时控制逻辑在MOS MB上决定了开或者关的周期(因此切换工作周期和频率)。
mode Iref is not acting as the sole current limitation level; the
detection of overcurrent phenomena is carried out by the Over-
I and Over-V detect block in Fig. 4. The described approach
注意,在切换模式Iref不是作为唯一的电流限制水平;检测过流现象是被运用于过压过流检测块,如图4所示。
allows to implement two functions in the same LED driver IC at
minimal hardware overhead: linear regulator mode, useful for
所述方法可以实现两个功能相同的LED驱动集成电路在最小的硬件开销:线性稳压器，用于瞬间的变化和低电流低功率LED，当电源效率不是问题的时候。
fast transient and low-current/low-power LEDs, where power
efficiency is not an issue; switch driving mode, useful for higher
开关驱动方式，用于高电流和高功率LED，当电源效率是关键问题所以
current and higher power LEDs where the power efficiency is a
key issue and therefore a switching regulator has to be preferred
to a linear one.
线性的开关稳压器将被成为首选。
The driving of a LED calls also for specific strategies to
avoid the ringing phenomenon on the connecting wire with
the consequent current overshoot. The Soft Start and Current
发光二极管的驱动也要求具体策略在连接线上避免振荡现象与随之产生的电流超调。
Slope Control techniques, proposed by the authors in [12] for
bulb lamp driving (low-power dashboard indicator), have been
improved to maintain the same proper behavior also with arrays
of LEDs and high luminosity up to 10W. The design has taken
软启动和电流斜率控制技术,作者在[12]中提出的灯泡驱动(低功耗
仪表板指示器),被用来保持适当的状态，同时也排列二极管把光度提高到10瓦特。
into account the variability of parasitic capacitors and inductors,
设计已经考虑到可变性的寄生电容和电感,
as well as of the load and all process-voltage-temperature (PVT)
以及负载和所有过程电压温度(PVT)的部分。
corners. As shown in Fig. 6, by sweeping through different
如图六所示，通过不同的布线寄生现象和等效电阻
对不同负载配置的发光二极管，
values of the wiring parasitics and of the equivalent resistance
for different LED-based load configurations, the phase margin
电压调节回路的相位补角,如图4所示，在一个相关的方式下变化。of the voltage regulation loop in Fig. 4 changes in a relevantway.
As a consequence, the susceptibility to instability of the overall
因此，
circuit varies, along with the entity of the ringing, as illustrated
不稳定的磁感系数的整体电路的变化,随着实体振荡，在图7中阐述的那样。
in Fig. 7. To deal with the wider range of possible values for the
load, compared to the previous bulb case study [12], the Current
处理各种复杂的负载的可能值,相比前一个灯泡案例研究[12], Slope Control, previously realized as a fixed technique, has
been tuned and made programmable through a digital interface.
当前电流控制,先前意识到作为一个完善的技术,已经被调整好并通过数字接口使其可编程。
The output current slope during the turn-on phase of the load
depends on how fast that power MOS is switched ON.
输出电流斜率在开机阶段的负载取决于MOS的开关开启的速度。Sincethe power MOS in Fig. 4 is driven by the output of the OTA, by
因为操作系统的是由OTA的输出驱动的，如图4，
controlling its slew rate it is possible to control the load current
slope. The slew rate of the OTA can be controlled by tuning
the dimensions of the transistors that compose the OTA (fixed
mode implemented in [12]) or by regulating its bias current, Ibias
通过斜率。转换速率可以控制通过调整控制它的转换速度,可以控制负载电流晶体管的尺寸组成OTA(固定模式实现在[12])或通过调节其偏置电流。
in Fig. 4, as done in this letter. Ibias is a configurable current
在图四，像这文章中说的，偏置电流是一个可配置的电流所产生的一个芯片上的带隙电路。
generated by an on-chip band-gap circuit. The programmability
of the Current Slope Control allows the employment of the smart
driver with different LEDs configuration, in order to keep down
the ringing.
这个可编程的电流升降控制允许使用的智能与不同的发光二极管驱动配置,为了降低偏振。
The supported switch driving mode is also useful to enable
the implementation of a Soft Start strategy against in-rush currents
that can cause overshoots and ringing phenomena. When
被支持的开关驱动方式也是用于启用实现软启动战略应对在高峰电流可引起超调量和偏振现象。
the output current lasts over a configurable current limit for
more than a configurable lapse of time, a Soft Start strategy is
当输出电流持续超过一个可配置一段时间的电流限制时,一个软启动策略将被采用，
adopted, switching the load by modulating the duty cycle and the
frequency (i.e., Ton and Toff ) parameters and hence controlling
the length of the turn-on phase.
开关负载的调制周期频率频率(即T开和T关)参数,从而控制开机阶段的相位。
As application example in Fig. 8, the time necessary to reach
the steady luminous state of a 10Wload can be greatly reduced
by modifying the duty cycle of the control signal (e.g., from
33% to 72% in the example of Fig. 8). Therefore, the Soft Start
作为应用在图8的例子,必要的时间到达稳定的发光状态10 w负载可以大大降低
通过修改工作周期的控制信号(如,从33%到72%的例子,图8)。strategy is a particular way of using the current control loop in
Fig. 4 and the control logic acting on the MB and the power
MOS transistors not for power efficiency issues, but to face inrush
因此,软启动方式是一种特定的方式来使用该电流控制回路，在图4控制逻辑作用于MB金属氧化物半导体晶体管的能量不是功率效率问题，
currents during fast turn-on LED transients. The drawback
但需要面对快速瞬变电流刺激的涌入。
by pushing this strategy to optimize time performance is the
risk of a die-overheating by supplying the maximum current
for a long period. To this aim, Over-Temperature Protection,
using on-chip temperature sensor, is integrated into the driver to
缺点是按这个策略来优化时间性能的的风险通过会长时间提供模具过热的最大电流。为达此目的,过热保护,使用芯片上的温度传感器。prevent the device to be damaged, by turning to a standby mode
the entire driver until a sufficient cooling has occurred.
集成到驱动为了防止设备损坏,转向一种待机模式直到整个驱动都变得足够冷却。
Finally, the device presents a low power absorption, a feature
extremely important for a LED driver IC. As shown in Table I,
最后,该设备提供了一个低功率吸收的一个功能非常重要的LED驱动集成电路。
the power absorbed by the logic controlling the power switching
如同在一部分提到的那样，逻辑控制功率切换控制着功率吸收。
TABLE I
POWER PERFORMANCE OF THE PROPOSED SMART DRIVER
表格1
智能驱动的动力性能
TABLE II
WIRING PARASITIC ESTIMATION
表格2
寄生接线的估算
MOS is almost negligible during turn OFF and power down
phases, and it is very low even during the turn ON of the load,
with a maximum of 1.2mW while driving a 1A load.
MOS在关掉电源中断阶段是几乎可以忽略不,即使它是在打开的负载情况下也是非常低的，大概最大在1.2 微瓦当带一个负载的时候。The main power switch MOS has been designed with a high
aspect ratio W/L to minimize its drain-to-source on resistance
and hence to minimize the power dissipation during the turn-on
主电源开关MOS已经被设计为一个高纵横比W / L来减少它的漏源极导通电阻从而来减少在开机阶段功耗。
phase. In experimental measures with 12 and 14V batteries,
Vref set to 1.2V, and 1A load, the power consumption is limited
to 1.2W over 12W and 14W, respectively (i.e., the measured
在实验时候用12和14 伏特的电池,Vref设置为1.2 伏特,一个1安培的负荷,功率消耗是限制分别在1.2瓦特到12瓦特和14瓦特。（测量功率效率要达到91.4%以上）
power efficiency is up to 91.4%). The minimum Vref value
is roughly 0.7V, limited by the voltage drop on the diode in
最低Vref值大概是0.7伏特,二极管的电压降限制如图4所示。
Fig. 4. Hence, with 1-A load current the power consumption
of the driver would be roughly 0.7W and, considering a 12-V
battery system, this leads to a maximum power efficiency of
因此,如果负载电流的功率消耗的驱动都是大概在0.7瓦特,考虑一个
毕业设计（论文） 外文翻译 题目西安市水源工程中的 水电站设计 专业水利水电工程 班级 学生 指导教师 2016年
研究钢弧形闸门的动态稳定性 牛志国 河海大学水利水电工程学院，中国南京，邮编210098 nzg_197901@https://www.doczj.com/doc/ae2710959.html,，niuzhiguo@https://www.doczj.com/doc/ae2710959.html, 李同春 河海大学水利水电工程学院，中国南京，邮编210098 ltchhu@https://www.doczj.com/doc/ae2710959.html, 摘要 由于钢弧形闸门的结构特征和弹力，调查对参数共振的弧形闸门的臂一直是研究领域的热点话题弧形弧形闸门的动力稳定性。在这个论文中，简化空间框架作为分析模型，根据弹性体薄壁结构的扰动方程和梁单元模型和薄壁结构的梁单元模型，动态不稳定区域的弧形闸门可以通过有限元的方法，应用有限元的方法计算动态不稳定性的主要区域的弧形弧形闸门工作。此外，结合物理和数值模型，对识别新方法的参数共振钢弧形闸门提出了调查，本文不仅是重要的改进弧形闸门的参数振动的计算方法，但也为进一步研究弧形弧形闸门结构的动态稳定性打下了坚实的基础。 简介 低举升力，没有门槽，好流型，和操作方便等优点，使钢弧形闸门已经广泛应用于水工建筑物。弧形闸门的结构特点是液压完全作用于弧形闸门，通过门叶和主大梁，所以弧形闸门臂是主要的组件确保弧形闸门安全操作。如果周期性轴向载荷作用于手臂，手臂的不稳定是在一定条件下可能发生。调查指出:在弧形闸门的20次事故中，除了极特殊的破坏情况下，弧形闸门的破坏的原因是弧形闸门臂的不稳定;此外，明显的动态作用下发生破坏。例如:张山闸，位于中国的江苏省，包括36个弧形闸门。当一个弧形闸门打开放水时，门被破坏了，而其他弧形闸门则关闭，受到静态静水压力仍然是一样的，很明显，一个动态的加载是造成的弧形闸门破坏一个主要因素。因此弧形闸门臂的动态不稳定是造成弧形闸门(特别是低水头的弧形闸门)破坏的主要原是毫无疑问。
外文翻译 专业机械设计制造及其自动化学生姓名刘链柱 班级机制111 学号1110101102 指导教师葛友华
外文资料名称： Design and performance evaluation of vacuum cleaners using cyclone technology 外文资料出处：Korean J. Chem. Eng., 23(6), (用外文写) 925-930 (2006) 附件： 1.外文资料翻译译文 2.外文原文
应用旋风技术真空吸尘器的设计和性能介绍 吉尔泰金，洪城铱昌，宰瑾李， 刘链柱译 摘要：旋风型分离器技术用于真空吸尘器 - 轴向进流旋风和切向进气道流旋风有效地收集粉尘和降低压力降已被实验研究。优化设计等因素作为集尘效率，压降，并切成尺寸被粒度对应于分级收集的50％的效率进行了研究。颗粒切成大小降低入口面积，体直径，减小涡取景器直径的旋风。切向入口的双流量气旋具有良好的性能考虑的350毫米汞柱的低压降和为1.5μm的质量中位直径在1米3的流量的截止尺寸。一使用切向入口的双流量旋风吸尘器示出了势是一种有效的方法，用于收集在家庭中产生的粉尘。 摘要及关键词：吸尘器; 粉尘; 旋风分离器 引言 我们这个时代的很大一部分都花在了房子，工作场所，或其他建筑，因此，室内空间应该是既舒适情绪和卫生。但室内空气中含有超过室外空气因气密性的二次污染物，毒物，食品气味。这是通过使用产生在建筑中的新材料和设备。真空吸尘器为代表的家电去除有害物质从地板到地毯所用的商用真空吸尘器房子由纸过滤，预过滤器和排气过滤器通过洁净的空气排放到大气中。虽然真空吸尘器是方便在使用中，吸入压力下降说唱空转成比例地清洗的时间，以及纸过滤器也应定期更换，由于压力下降，气味和细菌通过纸过滤器内的残留粉尘。 图1示出了大气气溶胶的粒度分布通常是双峰形，在粗颗粒（>2.0微米）模式为主要的外部来源，如风吹尘，海盐喷雾，火山，从工厂直接排放和车辆废气排放，以及那些在细颗粒模式包括燃烧或光化学反应。表1显示模式，典型的大气航空的直径和质量浓度溶胶被许多研究者测量。精细模式在0.18?0.36 在5.7到25微米尺寸范围微米尺寸范围。质量浓度为2?205微克，可直接在大气气溶胶和 3.85至36.3μg/m3柴油气溶胶。
理工学院毕业设计(论文)外文资料翻译 专业：热能与动力工程 姓名：赵海潮 学号：09L0504133 外文出处：Applied Acoustics, 2010(71):701~707 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 基于一维CFD模型下汽车排气消声器的实验研究与预测Takeshi Yasuda, Chaoqun Wua, Noritoshi Nakagawa, Kazuteru Nagamura 摘要目前，利用实验和数值分析法对商用汽车消声器在宽开口喉部加速状态下的排气噪声进行了研究。在加热工况下发动机转速从1000转/分钟加速到6000转/分钟需要30秒。假定其排气消声器的瞬时声学特性符合一维计算流体力学模型。为了验证模拟仿真的结果，我们在符合日本工业标准（JIS D 1616）的消声室内测量了排气消声器的瞬态声学特性，结果发现在二阶发动机转速频率下仿真结果和实验结果非常吻合。但在发动机高阶转速下（从5000到6000转每分钟的四阶转速，从4200到6000转每分钟的六阶转速这样的高转速范围内），计算结果和实验结果出现了较大差异。根据结果分析，差异的产生是由于在模拟仿真中忽略了流动噪声的影响。为了满足市场需求，研究者在一维计算流体力学模型的基础上提出了一个具有可靠准确度的简化模型，相对标准化模型而言该模型能节省超过90％的执行时间。 关键字消声器排气噪声优化设计瞬态声学性能 1 引言 汽车排气消声器广泛用于减小汽车发动机及汽车其他主要部位产生的噪声。一般而言，消声器的设计应该满足以下两个条件：（1）能够衰减高频噪声，这是消声器的最基本要求。排气消声器应该有特定的消声频率范围，尤其是低频率范围，因为我们都知道大部分的噪声被限制在发动机的转动频率和它的前几阶范围内。（2）最小背压，背压代表施加在发动机排气消声器上额外的静压力。最小背压应该保持在最低限度内，因为大的背压会降低容积效率和提高耗油量。对消声器而言，这两个重要的设计要求往往是互相冲突的。对于给定的消声器，利用实验的方法，根据距离尾管500毫米且与尾管轴向成45°处声压等级相近的排气噪声来评估其噪声衰减性能，利用压力传感器可以很容易地检测背压。 近几十年来，在预测排气噪声方面广泛应用的方法有：传递矩阵法、有限元法、边界元法和计算流体力学法。其中最常用的方法是传递矩阵法（也叫四端网络法）。该方
使用高级分析法的钢框架创新设计 1．导言 在美国，钢结构设计方法包括允许应力设计法(ASD)，塑性设计法(PD)和荷载阻力系数设计法(LRFD)。在允许应力设计中，应力计算基于一阶弹性分析，而几何非线性影响则隐含在细部设计方程中。在塑性设计中，结构分析中使用的是一阶塑性铰分析。塑性设计使整个结构体系的弹性力重新分配。尽管几何非线性和逐步高产效应并不在塑性设计之中，但它们近似细部设计方程。在荷载和阻力系数设计中，含放大系数的一阶弹性分析或单纯的二阶弹性分析被用于几何非线性分析，而梁柱的极限强度隐藏在互动设计方程。所有三个设计方法需要独立进行检查，包括系数K计算。在下面，对荷载抗力系数设计法的特点进行了简要介绍。 结构系统内的内力及稳定性和它的构件是相关的，但目前美国钢结构协会（AISC）的荷载抗力系数规范把这种分开来处理的。在目前的实际应用中，结构体系和它构件的相互影响反映在有效长度这一因素上。这一点在社会科学研究技术备忘录第五录摘录中有描述。 尽管结构最大内力和构件最大内力是相互依存的（但不一定共存），应当承认，严格考虑这种相互依存关系，很多结构是不实际的。与此同时，众所周知当遇到复杂框架设计中试图在柱设计时自动弥补整个结构的不稳定（例如通过调整柱的有效长度）是很困难的。因此，社会科学研究委员会建议在实际设计中，这两方面应单独考虑单独构件的稳定性和结构的基础及结构整体稳定性。图28.1就是这种方法的间接分析和设计方法。
在目前的美国钢结构协会荷载抗力系数规范中，分析结构体系的方法是一阶弹性分析或二阶弹性分析。在使用一阶弹性分析时，考虑到二阶效果，一阶力矩都是由B1,B2系数放大。在规范中，所有细部都是从结构体系中独立出来，他们通过细部内力曲线和规范给出的那些隐含二阶效应，非弹性，残余应力和挠度的相互作用设计的。理论解答和实验性数据的拟合曲线得到了柱曲线和梁曲线，同时Kanchanalai发现的所谓“精确”塑性区解决方案的拟合曲线确定了梁柱相互作用方程。 为了证明单个细部内力对整个结构体系的影响，使用了有效长度系数，如图28.2所示。有效长度方法为框架结构提供了一个良好的设计。然而，有效长度方法的
本科生毕业设计（论文）外文科技文献译文 译文题目(外文题目)学院(系)Socket网络编程的设计与实现A Design and Implementation of Active Network Socket Programming 机械与能源工程学院 专学业 号 机械设计制造及其自动化 071895 学生姓名李杰林 日期2012年5月27日指导教师签名日期
摘要：编程节点和活跃网络的概念将可编程性引入到通信网络中，并且代码和数据可以在发送过程中进行修改。最近，多个研究小组已经设计和实现了自己的设计平台。每个设计都有其自己的优点和缺点，但是在不同平台之间都存在着互操作性问题。因此，我们引入一个类似网络socket编程的概念。我们建立一组针对应用程序进行编程的简单接口，这组被称为活跃网络Socket编程（ANSP）的接口，将在所有执行环境下工作。因此，ANSP 提供一个类似于“一次性编写，无限制运行”的开放编程模型，它可以工作在所有的可执行环境下。它解决了活跃网络中的异构性，当应用程序需要访问异构网络内的所有地区，在临界点部署特殊服务或监视整个网络的性能时显得相当重要。我们的方案是在现有的环境中，所有应用程序可以很容易地安装上一个薄薄的透明层而不是引入一个新的平台。 关键词：活跃网络；应用程序编程接口；活跃网络socket编程
1 导言 1990年，为了在互联网上引入新的网络协议，克拉克和藤农豪斯[1]提出了一种新的设 计框架。自公布这一标志性文件，活跃网络设计框架[2，3，10]已经慢慢在20世纪90 年代末成形。活跃网络允许程序代码和数据可以同时在互联网上提供积极的网络范式，此外，他们可以在传送到目的地的过程中得到执行和修改。ABone作为一个全球性的骨干网络，开 始进行活跃网络实验。除执行平台的不成熟，商业上活跃网络在互联网上的部署也成为主要障碍。例如，一个供应商可能不乐意让网络路由器运行一些可能影响其预期路由性能的未知程序，。因此，作为替代提出了允许活跃网络在互联网上运作的概念，如欧洲研究课题组提出的应用层活跃网络（ALAN）项目[4]。 在ALAN项目中，活跃服务器系统位于网络的不同地址，并且这些应用程序都可以运行在活跃系统的网络应用层上。另一个潜在的方法是网络服务提供商提供更优质的活跃网络服务类。这个服务类应该提供最优质的服务质量（QOS），并允许路由器对计算机的访问。通过这种方法，网络服务提供商可以创建一个新的收入来源。 对活跃网络的研究已取得稳步进展。由于活跃网络在互联网上推出了可编程性，相应 地应建立供应用程序工作的可执行平台。这些操作系统平台执行环境（EES），其中一些已 被创建，例如，活跃信号协议（ASP）[12]和活跃网络传输系统（ANTS）[11]。因此，不 同的应用程序可以实现对活跃网络概念的测试。 在这些EES 环境下，已经开展了一系列验证活跃网络概念的实验，例如，移动网络[5]，网页代理[6]，多播路由器[7]。活跃网络引进了很多在网络上兼有灵活性和可扩展性的方案。几个研究小组已经提出了各种可通过路由器进行网络计算的可执行环境。他们的成果和现有基础设施的潜在好处正在被评估[8，9]。不幸的是，他们很少关心互操作性问题，活跃网络由多个执行环境组成，例如，在ABone 中存在三个EES，专为一个EES编写的应用程序不能在其他平台上运行。这就出现了一种资源划分为不同运行环境的问题。此外，总是有一些关键的网络应用需要跨环境运行，如信息收集和关键点部署监测网络的服务。 在本文中，被称为活跃网络Socket编程（ANSP）的框架模型，可以在所有EES下运行。它提供了以下主要目标： ??通过单一编程接口编写应用程序。 由于ANSP提供的编程接口，使得EES的设计与ANSP 独立。这使得未来执行环境的发展和提高更加透明。
毕业设计外文资料翻译 设计题目: 译文题目: 太阳能蒸笼 学生姓名： 学号： 专业班级： 指导教师： 正文：外文资料译文附件：外文资料原文
太阳能蒸笼 罗达.斯坦塔食品和营养学助理 许多不同的系统介绍了太阳能炊具。不同的设计有不同的优势。它也表明太阳能灶还处于初级阶段,将有希望有个美好的未来,不仅有助于解决气候变化问题,而且在做一件重要的事,服务许多人的生命。
大部份太阳能炊具有某种形式的反光罩的集中太阳的能量。太阳轮使用不反光但集中太阳能通过创造蒸汽从相对较大的收集器区域,并将其用于一个较小的烹饪区。随着太阳能轮使用蒸汽作为传热媒介,它是一种间接的烹饪系统。这允许一个分裂的烹饪系统,其热太阳能集热器可以放置在某个距离(如在屋顶上)除了烹饪的地方(例如在厨房里)。厨师正在不接触阳光的并且可以用蒸汽,无论高低都方便,可接受的区域。 这使它成为一个非常方便的炊具为大量的食物。使用简单叠加可以蒸煮几样菜，可以煮熟的同时进行。那热气腾腾的过程是非常相似与传统蒸煮过程，应该容易得到各种文化的认可。 太阳所产生的蒸汽也可以被用来热量大的罐炖肉或汤通过引导蒸汽直接进入了液体在它凝聚和释放的热凝。这就引起我做一个温柔的风潮的食品烤干。 在其设计技术,利用太阳船的有效性标准疏散管太阳能集热器可降低成本。 配料系统 可以看出从素描以上基本的想法是很简单的。太阳能收集器里装满了水。因为它具有极高的效率和良好的保温玻璃管的撤离开始沸腾的水会暴露在阳光下时。蒸汽会被引导到蒸笼以灵活的、蒸汽抗性软管。 连续系统
最后更复杂的,因为它必须确信,玻璃管永远不会变干的。一滴滴喂料系统集成式换热器提供了一条连续的淡水来代替水流失为蒸汽。这也防止了重建的盐和污染的太阳能集热器。因为这个系统包含了大量的沸腾的水在玻璃管,它具有使绝对肯定,没有压力,建立该体系。 成本 为了保持成本低，Sun2Steam正在出售一转换工具包可以很容易地安装在一个标准的低成本太阳能集热器。此套将直接来自澳大利亚,而太阳能收集器可直接来源于一个低成本的供应商。 一个太阳能集热器和20管直径和57mm 1.8米长，在中国是可以买到的大约200美元。转换组件包括500万绝缘软管取决于汇率蒸汽将大约200美元。成本增加25%,装船的税负导致的总费用为500美元左右的太阳能船没有安装费用和培训。 这使得轮船进入上部成本支架太阳能炊具。然而所有的材料都要持久和完整的炊具应该很容易超过了一生的10年。炉子可以很容易地帮助准备食物为10人。这使人均成本的太阳能减少至约五十美元。 也有一些额外的好处。太阳轮能生产大约5升的高质量的蒸馏水一天所产生的凝汽。一个可选的转换器将允许生产超过100升的安全、pasteurised饮水每天。报告描述太阳能蒸笼在这里可以找到: 大多数高海拔的烹饪和烘烤的指示不推荐补偿,直到你到达约6000英尺的海拔高度。居住在该地区,并且现在我住在怀俄明,是正确的,我们的高度范围你真正开始注重细微的差别,所以我已经学会补偿烤时和烹饪。 水沸腾时会出现在较低的温度在这里——这是由于减少了空气压力。你不会真正注意到什么大的差异在4000英尺,甚至在6000英尺,唯一的真正的区别是面带最微小的更久一点做饭,和糙米试你的耐心一点超过正常(以接近一个小时做饭,而不是通常的40分钟)。糖果还可以要求较长的沸腾时期达到各种球类或裂缝阶段。最引人注目的差异在这个高度是烤面包。蛋糕是一个倾向于看起来更温柔,更容易摔跤在中间。面包做一些有趣的事情。 蛋糕混合料通常会表明你应该添加额外的勺面粉加入混合,如果你是在高海拔超过5-6000呎。你可能需要补偿甚至更多,如果你是比那更高一些。
1. Introduction America is one of the countries that speak English. Because of the special North American culture, developing history and the social environment, American English has formed its certain unique forms and the meaning. Then it turned into American English that has the special features of the United States. American English which sometimes also called United English or U.S English is the form of the English language that used widely in the United States .As the rapid development of American economy, and its steady position and strong power in the world, American English has become more and more widely used. As in 2005, more than two-thirds of English native speakers use various forms of American English. The philologists of the United States had divided the English of the United States into four major types: “America n creating”; “Old words given the new meaning”; “Words that eliminated by English”;“The phonetic foreign phrases and the languages that are not from the English immigrates”[1]. Compared to the other languages, American English is much simple on word spelling, usage and grammar, and it is one of the reasons that American English is so popular in the world. The thesis analyzes the differences between American English and British English. With the main part, it deals with the development of American English, its peculiarities compared to that of British English, its causes and tendency. 2. Analyses the Differences As we English learners, when we learning English in our junior or senior school, we already came across some words that have different spellings, different pronunciations or different expressions, which can be represented by following contrasted words: spellings in "color" vs. "colour"; pronunciations in "sec-re-ta-ry" vs. "sec-re-try";
编号： 毕业设计(论文)外文翻译 （原文） 院（系）：应用科技学院 专业：机械设计制造及其自动化 学生姓名：邓瑜 学号：0501120501 指导教师单位：应用科技学院 姓名：黄小能 职称： 2009年 5 月20 日
The Injection Molding The Introduction of Molds The mold is at the core of a plastic manufacturing process because its cavity gives a part its shape. This makes the mold at least as critical-and many cases more so-for the quality of the end product as, for example, the plasticiting unit or other components of the processing equipment. Mold Material Depending on the processing parameters for the various processing methods as well as the length of the production run, the number of finished products to be produced, molds for plastics processing must satisfy a great variety of requirements. It is therefore not surprising that molds can be made from a very broad spectrum of materials, including-from a technical standpoint-such exotic materials as paper matched and plaster. However, because most processes require high pressures, often combined with high temperatures, metals still represent by far the most important material group, with steel being the predominant metal. It is interesting in this regard that, in many cases, the selection of the mold material is not only a question of material properties and an optimum price-to-performance ratio but also that the methods used to produce the mold, and thus the entire design, can be influenced. A typical example can be seen in the choice between cast metal molds, with their very different cooling systems, compared to machined molds. In addition, the production technique can also have an effect; for instance, it is often reported that, for the sake of simplicity, a prototype mold is frequently machined from solid stock with the aid of the latest technology such as computer-aided (CAD) and computer-integrated manufacturing (CIM). In contrast to the previously used methods based on the use of patterns, the use of CAD and CAM often represents the more economical solution today, not only because this production capability is available pin-house but also because with any other technique an order would have to be placed with an outside supplier. Overall, although high-grade materials are often used, as a rule standard materials are used in mold making. New, state-of-the art (high-performance) materials, such as ceramics, for instance, are almost completely absent. This may be related to the fact that their desirable characteristics, such as constant properties up to very high temperatures, are not required on molds, whereas their negative characteristics, e. g. low tensile strength and poor thermal conductivity, have a clearly related to ceramics, such as sintered material, is found in mild making only to a limited degree. This refers less to the modern materials and components
毕业设计外文资料翻译 题目POLISHING OF CERAMIC TILES 抛光瓷砖 学院材料科学与工程 专业复合材料与工程 班级 学生 学号 指导教师 二〇一二年三月二十八日
MATERIALS AND MANUFACTURING PROCESSES, 17(3), 401–413 (2002) POLISHING OF CERAMIC TILES C. Y. Wang,* X. Wei, and H. Yuan Institute of Manufacturing Technology, Guangdong University ofTechnology, Guangzhou 510090, P.R. China ABSTRACT Grinding and polishing are important steps in the production of decorative vitreous ceramic tiles. Different combinations of finishing wheels and polishing wheels are tested to optimize their selection. The results show that the surface glossiness depends not only on the surface quality before machining, but also on the characteristics of the ceramic tiles as well as the performance of grinding and polishing wheels. The performance of the polishing wheel is the key for a good final surface quality. The surface glossiness after finishing must be above 208 in order to get higher polishing quality because finishing will limit the maximum surface glossiness by polishing. The optimized combination of grinding and polishing wheels for all the steps will achieve shorter machining times and better surface quality. No obvious relationships are found between the hardness of ceramic tiles and surface quality or the wear of grinding wheels; therefore, the hardness of the ceramic tile cannot be used for evaluating its machinability. Key Words: Ceramic tiles; Grinding wheel; Polishing wheel
Advantages of Managed Code Microsoft intermediate language shares with Java byte code the idea that it is a low-level language witha simple syntax , which can be very quickly translated intonative machine code. Having this well-defined universal syntax for code has significant advantages. Platform independence First, it means that the same file containing byte code instructions can be placed on any platform; atruntime the final stage of compilation can then be easily accomplished so that the code will run on thatparticular platform. In other words, by compiling to IL we obtain platform independence for .NET, inmuch the same way as compiling to Java byte code gives Java platform independence. Performance improvement IL is actually a bit more ambitious than Java bytecode. IL is always Just-In-Time compiled (known as JIT), whereas Java byte code was ofteninterpreted. One of the disadvantages of Java was that, on execution, the process of translating from Javabyte code to native executable resulted in a loss of performance. Instead of compiling the entire application in one go (which could lead to a slow start-up time), the JITcompiler simply compiles each portion of code as it is called (just-in-time). When code has been compiled.once, the resultant native executable is stored until the application exits, so that it does not need to berecompiled the next time that portion of code is run. Microsoft argues that this process is more efficientthan compiling the entire application code at the start, because of the likelihood that large portions of anyapplication code will not actually be executed in any given run. Using the JIT compiler, such code willnever be compiled.
（ 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)
Shear wall structural design of high-level framework Wu Jicheng Abstract: In this paper the basic concepts of manpower from the frame shear wall structure, analysis of the structural design of the content of the frame shear wall, including the seismic wall shear span ratio design, and a concrete structure in the most commonly used frame shear wall structure the design of points to note. Keywords: concrete; frame shear wall structure; high-rise buildings The wall is a modern high-rise buildings is an important building content, the size of the frame shear wall must comply with building regulations. The principle is that the larger size but the thickness must be smaller geometric features should be presented to the plate, the force is close to cylindrical. The wall shear wall structure is a flat component. Its exposure to the force along the plane level of the role of shear and moment, must also take into account the vertical pressure. Operate under the combined action of bending moments and axial force and shear force by the cantilever deep beam under the action of the force level to look into the bottom mounted on the basis of. Shear wall is divided into a whole wall and the associated shear wall in the actual project, a whole wall for example, such as general housing construction in the gable or fish bone structure film walls and small openings wall. Coupled Shear walls are connected by the coupling beam shear wall. But because the
PLC technique discussion and future development T.J.byers Electronic Test Equipment-principles and Applications Princeton University .America Along with the development of the ages, the technique that is nowadays is also gradually perfect, the competition plays more strong; the operation that list depends the artificial has already can't satisfied with the current manufacturing industry foreground, also can't guarantee the request of the higher quantity and high new the image of the technique business enterprise. The people see in produce practice, automate brought the tremendous convenience and the product quantities for people up of assurance, also eased the personnel's labor strength, reduce the establishment on the personnel. The target control of the hard realization in many complicated production lines, whole and excellent turn, the best decision etc, well-trained operation work, technical personnel or expert, governor but can judge and operate easily, can acquire the satisfied result. The research target of the artificial intelligence makes use of the calculator exactly to carry out, imitate these intelligences behavior, moderating the work through person's brain and calculators, with the mode that person's machine combine, for resolve the very complicated problem to look for the best path. We come in sight of the control that links after the electric appliances in various situation, that is already the that time generation past, now of after use in the mold a perhaps simple equipments of grass-roots control that the electric appliances can do for the low level only; And the PLC emergence also became the epoch-making topic, adding the vivid software control through a very and stable hardware, making the automation head for the new high tide. The PLC biggest characteristics lie in: The electrical engineering teacher already no longer electric hardware up too many calculations of cost, as long as order the importation that the button switch or the importation of the sensors order to link the PLC up can solve problem, pass to output to order the conjunction contact machine or control the start equipments of the big power after the electric appliances, but the exportation equipments