Solar Tracker
David Crowe, Jeff McCormick, Joel Mitchell,
Thomas Stratton, Jeff Schwane
December 15, 2005
Duke University Smart House Pratt School of Engineering
Abstract
The Solar Tracker team was formed in the fall of 2005 from five students in an ME design team, and a Smart House liaison. We continued the work of a previous solar tracker group. The task was to design a prototype tracking device to align solar panels optimally to the sun as it moves over the course of the day. The implementation of such a system dramatically increases the efficiency of solar panels used to power the Smart House. This report examines the process of designing and constructing the prototype, the experiences and problems encountered, and suggestions for continuing the project.
1.Introduction
Solar tracking is the process of varying the angle of solar panels and collectors to take advantage of the full amount of the sun?s energy. This is done by rotating panels to be perpendicular to the sun?s angle of incidence. Initi al tests in industry suggest that this process can increase the efficiency of a solar power system by up to 50%. Given those gains, it is an attractive way to enhance an existing solar power system. The goal is to build a rig that will accomplish the solar tracking and realize the maximum increase in efficiency. The ultimate goal is that the project will be cost effective – that is, the gains received by increased efficiency will more than offset the one time cost of developing the rig over time. In addition to the functional goals, the Smart House set forth the other following goals for our project: it must not draw external power (self-sustaining), it must be aesthetically pleasing, and it must be weatherproof.
The design of our solar tracker consists of three components: the frame, the sensor, and the drive system. Each was carefully reviewed and tested, instituting changes and improvements along the design process. The frame for the tracker is an aluminum
prismatic frame supplied by the previous sol ar tracking group. It utilizes an …A-frame? design with the rotating axle in the middle. Attached to the bottom of this square channel axle is the platform which will house the main solar collecting panels. The frame itself is at an angle to direct the panels toward the sun (along with the inclination of the roof). Its rotation tracks the sun from east to west during the day.
The sensor design for the system uses two small solar panels that lie on the same plane as the collecting panels. These sensor panels have mirrors vertically attached between them so that, unless the mirror faces do not receive any sun, they are shading one of the panels, while the other is receiving full sunlight. Our sensor relies on this difference in light, which results in a large impedance difference across the panels, to drive the motor in the proper direction until again, the mirrors are not seeing any sunlight, at which point both solar panels on the sensor receive equal sunlight and no power difference is seen.
After evaluation of the previous direct drive system for the tracker, we designed a belt system that would be easier to maintain in the case of a failure. On one end of the frame is a motor that has the drive pulley attached to its output shaft. The motor rotates the drive belt which then rotates the pulley on the axle. This system is simple and easily disassembled. It is easy to
interchange motors as needed for further testing and also allows for optimization of the final gear ratio for response of the tracker.
As with any design process there were several setbacks to our progress. The first and foremost was inclement weather which denied us of valuable testing time. Despite the setbacks, we believe this design and prototype to be a very valuable proof-of-principle. During our testing we have eliminated many of the repetitive problems with the motor and wiring so that future work on the project will go more smoothly. We also have achieved our goal of tracking the sun in a …hands-off? demo. We were able to have the tracker rotate under its own power to the angle of the sun and stop without any assistance. This was the main goal set forth to us by the Smart House so we believe our sensed motion
prototype for solar tracking will be the foundation as they move forward in the future development and implementation of this technology to the house.
2. Defining the Problem
The project was to complete the “REV 2” design phase of the solar tracker to be used on the Smart House. While the team was comprised of members from the ME160 senior design course, the customer for this project was to be the Smart House organization. Jeff Schwane, a representative from the Smart House, was our liaison and communicated to our group the direction Smart House leadership wished us to proceed.
At our first meeting with Jeff and Tom Rose, the following needs were identified:
1.Track the sun during the day
https://www.doczj.com/doc/113268580.html,e no external power source
3.Weather proof
4.Cost effective power gain
5.Must look good
6.Solar panel versatile i.e. can fit different types of panels
With these needs in hand, we constructed a Quality Function Deployment chart. This chart can be found in Appendix A. The QFD showed the major areas of concern might have been: number of panels/size of panels, internal power requirements, motor torque required.
At our first meeting we were also able to set up our goals for the semester. Having a working prototype capable of tracking the sun was to be the main goal for the end of the semester, but we soon found that in order to accomplish this, we would be forced to omit portions of the design criteria in hopes they would be worked out later. This would result in the optimization of platform space on the roof to be irrelevant, with our goal being to have one platform track. It also led to the assumption that our base would not need to be tested for stability or required to be fastened to the roof. With an idea of where we were to begin, from scratch with the possibility of using the frame from the “REV 1” design, and an idea of where we were to finish, with a moving prototype, we constructed the Gantt
chart that can be found in Appendix B. Our group planned to meet with Jeff once a week to make sure we were on track with the needs of the Smart House. Jeff would also meet with Tom Rose, the director of Smart House, at least once a week in order to keep everyone on the same page. With our goals in mind we embarked on the process of idea generation.
3. Concepts and Research
3.1 Tracking Type
Our group used a brainstorming approach to concept generation. We thought of ideas for different solar tracking devices, which proved difficult at times due to the existing frame and concept presented to us by Smart House. Other concepts were generated through research of pre-existing solar tracking devices. Originally our concept generation was geared towards creating a completely new solar tracker outside of the constraints of the previous structure given to us by Smart House. This initial brainstorming generated many concepts. The first one was a uni-axial tracking system that would track the sun east to west across the sky during the course of a day and return at the end of the day. This concept presented the advantage of simplicity and presented us with the option to use materials from the previous structure (which was also intended to be a uni-axial tracker) in construction. Another more complex concept was to track the sun bi-axially which would involve tracking the sun both east to west and throughout the seasons. The advantage of this concept was a more efficient harvesting of solar energy. The third concept was to only track throughout the seasons. This would provide small efficiency gains but nowhere near the gain provided by tracking east to west.
The different structures we came up with to accomplish tracking motion included a rotating center axle with attached panels, hydraulic or motorized lifts which would move the main panel in the direction of the sun, and a robotic arm which would turn to face the sun. The clear efficiency gains coupled with the simplicity of design of the uni-axial tracking system and the existence of usable parts (i.e. motor and axle) for the rotating center axle structure, led us to the choice of the East to West tracking, rotating center axle
concept.
3.2 Structure
Once the method of motion was chosen, it was necessary to generate concepts for the structural support of the axle. Support could be provided by the triangular prismatic structure which was attempted by the previous Smart House solar tracker group or through the use of columns which would support the axis on either side. While the prismatic structure presented the advantage of mobility and an existing frame, the columns would have provided us with ease of construction, simple geometric considerations, and ease of prospective mounting on the roof. Due to the heightened intensity of time considerations, the previous financial commitment to the prismatic structure by Smart House, and our limited budget, the presence of the pre-existing frame proved to be the most important factor in deciding on a structure. Due to these factors we decided to work within the frame which was provided to us from the previous Solar Tracker group.
3.2 Tracking Motion
Once the structural support was finalized we needed to decide on a means to actualize this motion. We decided between sensed motion, which would sense the sun?s position and move to follow it, and continuous clock type motion, which would track the sun based on its pre-determined position in the sky. We chose the concept of continuous motion based on its perceived accuracy and the existence of known timing technology. During the evaluation stage, however, we realized that continuous motion would prove difficult. One reason was the inability to draw constant voltage and current from the solar panels necessary to sustain consistent motion, resulting in the necessity for sensing the rotation position to compensate. Continuous motion also required nearly constant power throughout the day, which would require a mechanism to store power. Aside from these considerations, the implementation of a timing circuit and location sensing device seemed daunting. After consulting Dr. Rhett George, we decided on a device using two panels and shading for sensed motion.
4. Analysis and Embodiment
4.1 Structure Geometry
The geometry of the frame was created in order to allow the solar panels to absorb light efficiently. This was done by allowing rotation in the east-west direction for tracking the sun daily and a 36° inclination (Durham?s latitu de) towards the south. Because this frame was designed to be placed on a roof with a slope of 25°, the actual incline of the frame was made to be 11°.
The geometry of the existing platform structure was modified. This was done in order to incorporate the results from the Clear Day Model supplied to us by Dr. Knight. This model led to the conclusion that the platform should track to up to 60° in both directions of horizontal. Thus, the angle range of the frame had to be increased. The sides of the frame were brought in to increase the allowable angle of rotation, and they were brought in proportionally to maintain the inclination angle of 11°. Also, crosspieces were moved to the inside of the frame to allow greater rotation of the platform before it came into contact with the support structure.
The panels used for sensing and powering rotation were placed on the plane of the platform. Mirrors were placed perpendicular to and in between the panels to shade one and amplify the other in order to produce a difference to power the motor. The sensing panels were placed outside the platform area to maintain the largest area possible for collecting panels. A third sensing panel was mounted nearly vertical and facing east to aid rotation back towards the sun in the morning. This panel was attached to the frame under the platform, so that during most of the day, it?s shaded with minimal effects on sensed rotation.
Minimizing the torques on the motor was a main concern in order to minimize the motor power needed. The platform designed for the placement of the collecting solar panels was placed under the rotational shaft so that the panels would be aligned with it the rotational axis. Since the main panels comprise the majority of the weight putting these in the plane of the rotational axis reduces torque on the shaft. The sensing panels were placed symmetrically about the axis of rotation in order to prevent additional torque on the
motor. The third panel was attached to the frame instead of the platform or rotational shaft so as to also avoid any torque.
4.2 Materials
Materials selection for most of the frame was simple because it had already been constructed. The mirrors used for the amplification and shading of the sensing panels were also already purchased and available for use. Additional parts for attachment of the panels and mirrors to the frame were taken from the scrap pieces available in the machine shop. In our selection of sensing panels, size and power needed to be balanced effectively. The panels were to be as small as possible in order to add minimal stress and weight to the frame but also needed to be powerful enough to power the rotation of the platform. Therefore, the most powerful of the intermediate sized panels available were selected. The panels purchased also appeared to be the most reliable of our options.
4.3 Drive Mechanism
After designing a prototype and testing it, the motor purchased and used by the previous solar tracker group was slipping. It was removed, and the installation of a gear system with another simple motor was suggested and attempted. Professor Knight supplied some gears as well as some belts and pulleys. One end of the shaft was lathed so that one of the pulleys could be set on it, and spacers were bought so that a 6V motor we had available could power another pulley. These pulleys were to be connected by a belt. This motor demonstrated insufficient strength to turn the rotational shaft. The original motor, once detached, was taken apart and examined. Itappeared to be working again so a new pulley was purchased to fit it and was attached in the place of the 6V motor.
5. Detailed Design
5.1 Frame
The frame was designed from one inch square aluminum tubing, and a five foot long, two inch square tube for the axle. It is constructed with a rigid base and triangular prismatic frame with side supporting bars that provide stability. The end of the axle is attached to a system of pulleys which are driven by the motor. It is easily transported by
removing the sides of the base and folding the structure.
5.2 Sensor
Our sensing panels are bolted to the bottom of the main solar panel frame and braced underneath with half inch L-brackets. The mirrors are attached to the inside of the sensing panels and braced by L-brackets as well. The whole structure attaches easily to the main panel frame which is attached to the main axle using four 2-inch U-bolts. A third panel is bolted to the structure to return the main panels direction towards the horizon of sunrise.
5.3 How the Sensor Works
Our sensor creates movement of the motor by shading one of the panels and amplifying the other when the system is not directly facing the sun. The two sensing panels are mounted parallel to the main panels symmetrically about the center axle with two mirrors in between them. The shading on one of the panels creates high impedance, while the amplified panel powers the motor. This happens until the panels receive the same amount of sunlight and balance each other out (i.e. when the sensing panels and main panels are facing the sun.). We initially attempted using a series configuration to take advantage of the voltage difference when one of the panels was shaded (Appendix C). This difference, however, was not large enough to drive the motor. We subsequently attempted a parallel configuration which would take advantage of the impedance of the shaded panel (Appendix C) and provide the current needed to drive the motor. Once the sensing mechanism has rotated from sunrise to sunset, the third panel, which is usually shaded, uses sunlight from the sunrise of the next day to power the motor to return the panels towards the direction of the sun.
6. Prototype Testing
Initial testing was done using just the sensing component and a 6V motor. The panels were tilted by hand to create shading and amplification. A series configuration of the sensing panels was initially tested and proved ineffective. Data acquisition showed a maximum of a 2V difference across the motor, which was insufficient to power it. Upon testing the panels individually, it was discovered that the open voltage across each
individual panel would only vary between 21.5V and 19.5V when fully amplified and fully shaded, respectively. The current running through each panel, however, was seen to fluctuate between nearly 0 amps when shaded, up to 0.65 amps when fully amplified. Therefore, in order to take advantage of the increase in impedance of the solar panels due to shading, we chose to put our sensing panels in parallel with each other and the motor. Tests with this configuration turned the motor in one direction, stopped when the sensing panels were nearly perpendicular to the sun, and reversed direction as the panels rotated past perpendicular. We found the angle range necessary to stop the motor to be very small. It was also observed that the panels rotated to slightly past perpendicular when they ceased motion. This error may be due to a difference in the innate resistance in each individual sensing panel. When tested it was found that one panel had a resistance of 52 kΩ, and the other panel resistance was 53 kΩ. Other testing found the voltage and current provided by the sensing solar panels to the motor to be consistent at all points, excluding when the solar panels are directly facing the sun. Through testing it was concluded that resistance may need to be added to one of the panels to compensate for the differences in the internal resistances of the individual panels, and a voltage regulator needs to be added to decrease the voltage seen across the motor. The original motor was prone to failure as its slippage caused the breakdown of our initial prototype after testing. This led to the institution of the pulley and belt driven system which would allow for easier maintenance given motor failure or slippage. The success of our initial testing and prototype proved to us the efficacy of our solar tracker design.
7. Conclusion
Throughout this project we enlisted the support of multiple resources (i.e. ME and EE professors, previous Smart House teams). We learned early on that a clear problem definition was essential to efficient design and progress. We struggled initially as we tried to design a tracking device that was different from the previous solar tracker group?s attempt, without fully weighing the size of their investment and the advantages of using the existing frame for our purposes. As we worked with the fixed frame construction from the
previous group we learned that variability of design is key, especially when in the initial phases of prototyping. After many setbacks in testing of the solar panels, we learned that when working with solar panels, much time needs to be set aside for testing due to the unpredictability of the weather.
The actual implementation of using the prototype in its intended location on the Smart House roof requires weather-proofing to protect the wiring and electrical connections from the elements, housing for the motor, a bracing system to attach the structure to the roof, and possible redesign to eliminate excess height and simplify overall geometry. The efficiency of the sensor system could be improved by widening the mirrors or by placing blinders along the sides of the panels to decrease the effects of reflected and refracted light incident on the shaded sensing panel.
太阳能跟踪器
大卫克罗、杰夫麦考密克、乔尔米切尔、
托马斯斯特拉顿、杰夫泰森
2005 年 12 月 15 日
杜克大学智能家居
普拉特工程学院
摘要
太阳跟踪团队成立于 2005 年秋季，五名普拉特学院学生在我的设计团队及与智能家居联络。我们继续先前的太阳能跟踪器的工作，任务是设计太阳能跟踪器原型以最佳方式向太阳对齐，一天跟随太阳移动。这种跟踪的执行情况明显增加了用于智能的房子供电的太阳能电池板的效率。本报告审查过程中设计和建造原型、经验和遇到的问题和建议的项目继续实施的过程。一、导言
太阳能跟踪是通过改变太阳能电池板角度来充分利用太阳能的过程。这通过旋转面板的始终垂直于太阳入射角实现的。这是通过旋转面板使其始终垂直于太阳的入射角。行业中的初始测试表明这一过程可以增加太阳能发电系统的效率达 50%。鉴于这些结果说明这是一个有吸引力的方式，以加强现有的太阳能发电系统。目标是建立一个跟踪机制，完成太阳能跟踪，并实现最高的效率。最终目标是，该项目要符合成本效益，那也就是说随着时间的推移将大大降低发展跟踪机的成本。除了上述功能目标。只能家居还为我们提出以下的其他目标：必须不吸取外部电源自我维持，必须美观而且还要能防水。
我们设计的太阳能跟踪器包括三个组成部分：结构，传感器和驱动器。每个都被仔细审查和检测，实行跟踪。先前的太阳能跟踪小组设计的框架是一个铝棱柱型框架。它采用了一种‘格’设计并且旋转轴在中间，与方形电池板底部相连的是一个用来支撑集热板的平台。该框架本身有一个角度，此角度的度数由小组对当地的实际情况调查而定，其旋转的轨道是系统随太阳从东到西的转动，这一过程在白天进行。
该传感器系统设计采用了两个小型太阳能电池板作为跟踪机的采集板。这些传感器面板采用垂直的反光镜相连接，除非反光镜接收不到任何阳光，不然它会遮挡其中一面板，而另外一个能够接收到太阳光。我们的传感器依靠这种差异继续研究，结果两种差异很大的面板都能驱动电机
跟踪方向，知道反光镜子再次得不到任何阳光，而此时双方的太阳能板对传感器能得到同等阳光。
我们认为以往用于跟踪直接驱动系统很容易在跟踪时失败。所以我们设计了一个带系统，系统的一端是马达，具有传动皮带轮和输出的功能。电机旋转传动皮带，然后旋转滑轮上的轮轴。这个系统简单，易于拆解，所以很容易根据需要将传动做进一步改进和优化。
正如任何涉及过程中都会遇到问题。我们遇到的首问题是天气恶劣二耽误我们宝贵的测试时间。尽管遇到挫折，我们相信，这样的设计与原型是非常有价值的。在我们的测试中，我们已经消除了许多重复的问题，使今后的工作和该项目的研究更为顺利。我们也已将我们的样机做跟踪太阳的演示，在没有任何外部辅助下，我们能让跟踪器依靠自己的能量旋转和停止，演示过程中没有任何援助。联合国向我们提出的智能家居的主要目标是：在今后的发展中将这项技术推广到普通家族。所以我们相信我们研究一定能使太阳能跟踪向前迈一步。
二、问题设定
该项目完成了太阳能跟踪器设计阶段的任务，以用于智能家居。而团队组成后，成员完成高级程序设计，客户可以为这个项目进行内部设计。智能提一下的是，杰夫泰森代表智能家居与我们进行联系和沟通，以及聪明的众议院领导也认同我们的研究。在我们的第一次会议上，杰夫和汤姆确定了以下目标：
a 白天追踪太阳
b 不使用任何外部电源
c 不受天气影响
d 符合成本效益
e 必须外观好看
f 太阳能电池板大众化即能够适用于不同类型的面板
根据这些目标，我们构建了质量功能配置图。此图可以发现，其主要关注的领域可能有以下几个：面板数量，面板尺寸，内部电源要求，电动机的扭矩要求。
在我们的第一次会议上，我们设定了我们这一阶段的目标：做出一个工作原型，能够跟踪太阳。这也是完成该项目的主要标准，但我们很快发现要做到这一点，我们将被迫省略部分的设计，他们希望工作列其后，这将导致在优化平台空间时是不是屋顶无关重要。我们的目标要有一个平台上的轨道，它也说明了为了稳定或需要，我们的原型需要测试。我们开始有个想法，这一想法从无到有，就是有可能使用帧，舍弃最初的设想即采用REV1设计方案或者采用转动原型方案，
我们的设计图见附件B，以应付与杰夫每周一次的会议，以确保我们在设计时能够满足他们的需要。杰夫也将会见汤姆，总之与智能家居的会议每周至少一次，以使每个人都能在同一高度上。从我们的目标开始，我们着手对这一进程进行构想。
三、观念和研究
3.1跟踪模式
我们小组用了一个集思广益的方法来界定概念。我们的思想理念是为了设计不同条件下使用的太阳能跟踪装置，因为它们克服不了不同条件下的困难，再把可行的框架和概念介绍给我们的智能家居。其他的概念产生式通过研究实现存在的太阳能跟踪装置得到的。原来我们的概念是面向创造一个完全新的太阳能跟踪装置，以前的设计结构方法已经给我们的智能家居提供了思路。这一初步献策产生了许多观点：第一个观点是一个单轴跟踪系统，该系统将追踪太阳从东到西横跨天空的全过程，检测每一段时间，知道第二天结束。这一概念的提出很简单，我们选择使用结构材料正在制作中；另一种更复杂的概念是双轴跟踪系统，并在整个季节都能从东到西跟踪太阳。这种概念是较为高效率的利用太阳能；第三个概念是只随季节跟踪。这将提供小型效率收益，但远不及第二个概念提供的从东到西的跟踪。
我们设计的跟踪装置后包括一个旋转中心轴和附加板以及液压机或电动升降机，将提供主要方向的跟踪，还有一个机械臂将使它旋转面对太阳。清晰的效率收益，再加上设计简单的单轴单向轴跟踪系统，以及以电机轴为旋转中心轴的结构，使我们能够实现从动到西的跟踪。
3.2结构
一旦方法的议案被选择，有必要使产生的观念、结构支撑车轴。课提供三角棱柱结构，也就是说由前面的智能家居太阳能跟踪，或通过使用栏目将对任何一方提供支持。而棱柱结构提交的优势和现有的框架、栏目会为我们提供方便的建设，简单的几何考虑，并准确安装在屋顶上。由于提高了强度的时间考虑，而我们的预算又有限，再加上现有的框架被证明是最重要的因素，由于这些因素，我们决定用过去的太阳能跟踪器组向我们提供的工作框架。
3.3跟踪运动
一旦支撑结构确定，最后我们需要一种手段来解决这项议案，我们决定之后感受这一议案的可行性，这将使太阳能跟踪器的研究方向和进度向前一步。在连续讨论议案之后，决定在太阳能跟踪太阳的基础上，预先确定太阳在天空中的位置，所以我们选择连续跟踪太阳能的议案，就是根据其知觉的准确性和存在的已知定时技术进行。在评估阶段我们意识到：连续跟踪的议案还需
要近恒定的功率，一天的运作中这将需要一个机制来储存能量。除了这些因素，实施的时间安排电路和位置传感装置似乎是艰巨的。与博士乔治协商后，我们决定对装置使用两个模块和底纹为感受的议案。
四、分析与体现
4.1 结构几何
创造几何学的框架，以使电池板吸收高效的太阳能。之所以能这样做，是让轮换在东西方向的电池板始终对南，每天跟踪太阳一个360°倾角（达勒姆的维度）。因为这个框架的目的是摆在屋顶25°的斜坡上，但实际的倾斜度是11°。
对现有的几何平台的结构作调整，这样做事为了博士奈特给我们的晴天模式，这种模式导致的结论是：该平台应当跟踪到达到60°两个方向是水平。因此，角度范围的框架尚待提高。把双方的帧引入以增加允许的转动角度，而他们带来的比例以维持倾角11°。此外，帧被转移到里面的框架以允许更大的旋转平台来接触到支持结构。
该面板放在用于传感器和驱动平台上。镜子垂直放置，并在这两者之间产生一个差额，带动功率电机。传感板放在外面的平台区，以保持收集板的最大可能面积。第三个传感模块张开近于直立，并且面向东，以确保在早晨乱换时回到太阳升起处。这个模块被连接到框架下的平台，因此，在一天的大部分时间里，它的阴影与影响是最小的。
最小力矩马达是一个主要的关注点，以最大限度的减少电机功率的需要。该平台设计用于安置太阳能电池板划归转动轴，使该小组模块符合它的旋转轴。由于主要有展板组成，其中大部分的重量使这些旋转轴降低了对轴的扭矩。传感板置于对称轴左右旋转，以避免额外对马达的扭矩。第三个模块是隶属于该帧而不是平台或者转动轴等，以尽量避免任何扭矩。
4.2材料
材料的选择，大部分的框架很简单，因此它已经建成。用于扩增和遮阴传感板的镜子，也已购买，并已使用。新增部分附着的板和后视镜框都是废品，可在车间找到。对于我们选择的传感面板的体积和耗电量都需要加以平衡。该模块将尽可能添加最小应用力和重量，而框架还需要得到足够强大的力量旋转平台，因此世界上最强大的中间尺寸面板可供选择。该模块还购买了其他最可靠材料来我们的选择。
4.3传动机构
经过重新设计原型和测试，电动机的购买和使用由先前的太阳能组完成。与会者建议把它拆
除并试图安装了一个齿轮系统与另一个简单的动作。奈特教授提供的一些装备以及一些皮带和滑轮与另一端的轴连接，在定这件事期间分别买了一个充电器和电机，我们可以从另一个权力滑轮将这些滑轮接上皮带。这表明电动机带动旋转轴强度不足，原电机轴离被送走去检验，这似乎又增加了新的工作，一个新的滑轮需要购买并在所附的地方要适应该6V马达。
五、详细结构
5.1结构
框架的是以一寸方的方形铝管为油管，以及5英寸长，2英寸的方管为轮轴。它是一个刚性基层和三角菱柱型框。轮轴末端与一个滑轮系统相连，这个系统是靠发动机驱动的。这是很容易运送消除双方的基地和折叠结构。
5.2 传感器
我们的传感面板螺栓到地步的主要太阳能电池板框架，支撑在下面的是一个半英寸的L-支架。镜子都附在传感器面板中，同样由L-支架支撑。整个框架用4个2英寸的u型螺栓将主面板框架连接到主轴。第三仪表盘是用螺栓固定在结构上，以此来返还主仪表向着太阳升起的方向。
5.3 传感器如何工作
Our sensor creates movement of the motor by shading one of the panels and amplifying the other when the system is not directly facing the sun.我们的传感器电机的运动产生的阴影面板和放大了其他当系统没有直接面向太阳。两个传感版装在平行主面板左右对称的中心轴与两面镜子之间。阴影对其中的面板造成了高阻抗，这种情况知道面板得到同样数量的阳光和平衡（即当传感面板及主要面板都朝外）。我们最初试图用一系列配置，以充分利用电压差时，这里又其中一小组的阴影（附录C）。这种差异也不是大到足以驱动马达。从日出到日落一旦感应机制有旋转，利用太阳光从日出的第二天功率电机归还板方向的太阳，第三个小组通常会被填满。
六、原型测试
测试工作只用传感元件和16v电机。该小组成员经过一系列的配置后，其传感面板进行最初测试，结果证明是无效的。数据采集显示，最多不超过2v的差异，这是不够准确的。经测试面板的整体，人们发现这是一个随意的电压，每个小组肯定各不相同，当21.5v和19.5v时应充分补充，并迅速充分填满。目前这些数据分别由没一个小组去实验，忧郁被认为波动中为0安培之间时被填满，直至0.65安培时充分补充，因此，为了充分避免太阳能电池板被遮光，我们选择
了把我们的传感器平行与阳光垂直。测试此配置，使得点击在一个方向停下时，传感器几乎垂直于太阳，如果太阳扭转了方向同时面板旋转过去保持与太阳光的垂直。我们调整角度的范围，要使电动机停止时误差非常小。也有人指出，面板旋转稍近垂直时，电机不再工作。这个错误可能是由于二个传感小组的结合。测试时，我们发现其中一个小组的阻力是52kw，其他小组的阻力为53kw。再进行深一步测试，发现电压和电流提供传感太阳能电池板向着太阳，在个点上以保持一致，但不包括当太阳能电池板直接面向太阳时。通过其中一个调查小组测试结果表明，阻力可能需要补充，以弥补分歧，在内部电阻的个体面板上稳压器需要加以补充，以减少电压误差而出现马达转动。我们最初的原型测试发现因为它的工程延误所造成的崩溃，所以原发动机容易失败的。这导致了该机构的滑轮和皮带驱动系统出现故障，并且将允许故障或延误继续。我们的太阳能跟踪器的设计初步测试和原型证明了我们的成效。
第七章结论
整个项目中，我们邀请了许多专家（即我和EE教授，以前智能家居队）。早在前面说过，必须明确定义问题，是至关重要的，这是提高设计效率和进展情况所必需的。我们的奋斗让我们得到了最初的一二跟踪装置的设计，这是不同于以往太阳能需求者的企图，但无充分权衡利弊大小，决定利用现有框架，他们的投资和优势为我们的目的提供了帮助。我们了解到，进行部分的设计是关键，尤其是当在初始阶段的原型设计中。几经周折，在测试太阳能电池板时我们才知道，忧郁不可预测性天气，太阳能电板工作需要很多时间去测试是否与太阳垂直有关。
实际执行的使用原型在其预定位置对智能家居屋顶的样机一样，以保护线路及电气连接，从传感，结构到电机，支撑体系，底部结构放于屋顶，并有可能重新设计以消除过剩的高度和简化整体的几何形状。传感系统可以加以改进，以得到高效率，使得扩大镜或配售沿线两侧的面板，以减少折射光对传感器的影响。
forced concrete structure reinforced with an overviewRein Since the reform and opening up, with the national economy's rapid and sustained development of a reinforced concrete structure built, reinforced with the development of technology has been great. Therefore, to promote the use of advanced technology reinforced connecting to improve project quality and speed up the pace of construction, improve labor productivity, reduce costs, and is of great significance. Reinforced steel bars connecting technologies can be divided into two broad categories linking welding machinery and steel. There are six types of welding steel welding methods, and some apply to the prefabricated plant, and some apply to the construction site, some of both apply. There are three types of machinery commonly used reinforcement linking method primarily applicable to the construction site. Ways has its own characteristics and different application, and in the continuous development and improvement. In actual production, should be based on specific conditions of work, working environment and technical requirements, the choice of suitable methods to achieve the best overall efficiency. 1、steel mechanical link 1.1 radial squeeze link Will be a steel sleeve in two sets to the highly-reinforced Department with superhigh pressure hydraulic equipment (squeeze tongs) along steel sleeve radial squeeze steel casing, in squeezing out tongs squeeze pressure role of a steel sleeve plasticity deformation closely integrated with reinforced through reinforced steel sleeve and Wang Liang's Position will be two solid steel bars linked Characteristic: Connect intensity to be high, performance reliable, can bear high stress draw and pigeonhole the load and tired load repeatedly.
水平单轴跟踪系统 水平单轴跟踪系统是指光伏方阵可以绕一根水平轴东西方向跟踪太阳。跟踪系统主要由：太阳能电池组件安装支架、水平转轴、转动驱动机构、风速检测装置和跟踪控制器组成。 特点及应用：这种跟踪装置结构特点是结构简单、成本较低、更适合于纬度较低的地区，发电效率比固定纬角的固定式结构高30%左右。可以安装在地面也可以安装在屋顶。 极轴式单轴跟踪系统 极轴式单轴跟踪系统具有一根固定纬角的转轴，光伏方阵可以绕该转轴东西向旋转跟踪太阳。跟踪系统主要由：光伏组件安装支架、转轴、支架、电动推杆、风速探头及跟踪控制器组成。 特点及应用：这种跟踪系统的特点是结构最简单，造价最低。比较适合纬度较高的地区使用，发电效率比固定纬角的固定式系统高30%以上。可以安装在地面也可以安装在屋顶。 阵列式双轴跟踪系统 这种系统具有一根南北方向的纵向转轴和固定在纵向轴上的多根横向转轴组成，每块太阳能组件小方阵既可绕纵向轴东西向转动又可绕横向转轴上下旋转。跟踪系统主要由：纵向转轴、横向转轴、东西向推杆、高度角推杆、连杆、支架、组件安装支架、向日跟踪探头、风速探头及跟踪控制器组成。
特点及应用：与水平单轴跟踪相比，实现了双轴跟踪，发电效率更高，比固定纬角的固定结构高45%以上，与立柱式跟踪相比，系统的高度更低，抗风性能更好，单位面积的安装功率更高。既可安装在地面也可安装在屋顶。 立柱式双轴跟踪系统 有一根立轴和一根水平轴，整个光伏方阵由一根立柱支撑，光伏方阵既可绕立轴跟踪太阳的方位角，同时绕水平轴跟踪太阳的高度角，它完全无限制地跟踪太阳方位，最大限度地发挥跟踪系统的效能。跟踪系统主要由：组件安装支架、水平轴、水平动力头、电动推杆、立柱、向日跟踪探头、风速探头、跟踪控制器等组成。 特点及应用：跟踪范围最大、跟踪效率最高，比固定纬角的固定结构高50%以上。一般仅适合安装在地面
本科毕业设计 外文文献及译文 文献、资料题目：Solar Urban Planning and Design 文献、资料来源：期刊 文献、资料发表（出版）日期：2011.5.12 院（部）： 专业： 班级： 姓名： 学号： 指导教师： 翻译日期：
外文文献： Solar Urban Planning and Design Abstract: In recent decades, urban population growth, the acceleration of energy consumption and energy price, the increase of public concerns about environmental pollution and the demolition of nonrenewable energies, have adverted the attention of different groups to the use of sustainable, available and clean solar energy as a sustainable energy. Specialists like architects and engineers have considered solar energy in designing systems, buildings and equipments. Straggle success achieved in the case, cause the progress of replacing solar systems in buildings and equipments instead of systems consuming unsustainable resources like fossil fuel to be accelerated. But they have not applied coherently yet. In other words, before the enforcement of solar projects in cities, it is necessary to note all the dimensions related to their execution in order to reach their optimum efficiency. The goal that could be attained by long-time and multi dimensional planning. This paper guides the focus of urban and town planning and design on the application of solar energy. That urban planners should consider three aspects of environment, economy and society in three related elements of cities consisting buildings and urban spaces, urban infrastructures and urban land uses to achieve sustainable goals is discussed in this paper. So, after the review of few experiences, the issues and guidelines whose consideration lead to the more efficient solar urban planning and design are outlined. Key words:Solar Urban Planning- Solar Potential- Sustainable City- Solar Master Plan- Smart Infrastructure 1. Introduction: the increase of attention to solar energy The increase of urban population, activities and technologies using fossil fuels, energy price, energy consumption and the increase of public concerns about environmental pollution and the destroy of non-renewable energy resources, are causing different experts including specialists related to building and construction to look for alternative ways of energy provision. Building professionals have not considered the aim of good design aesthetically more and try to design the
(文档含英文原文和中文翻译) 中英文翻译 平面设计 任何时期平面设计可以参照一些艺术和专业学科侧重于视觉传达和介绍。采用多种方式相结合，创造和符号，图像和语句创建一个代表性的想法和信息。平面设计师可以使用印刷，视觉艺术和排版技术产生的最终结果。平面设计常常提到的进程，其中沟通是创造和产品设计。 共同使用的平面设计包括杂志，广告，产品包装和网页设计。例如，可能包括产品包装的标志或其他艺术作品，举办文字和纯粹的设计元素，如形状和颜色统一件。组成的一个最重要的特点，尤其是平面设计在使用前现有材料或不同的元素。 平面设计涵盖了人类历史上诸多领域，在此漫长的历史和在相对最近爆炸视觉传达中的第20和21世纪，人们有时是模糊的区别和重叠的广告艺术，平面设计和美术。毕竟，他们有着许多相同的内容，理论，原则，做法和语言，有时同样的客人或客户。广告艺术的最终目标是出售的商品和服务。在平面
设计，“其实质是使以信息，形成以思想，言论和感觉的经验”。 在唐朝（ 618-906 ）之间的第4和第7世纪的木块被切断打印纺织品和后重现佛典。阿藏印在868是已知最早的印刷书籍。 在19世纪后期欧洲，尤其是在英国，平面设计开始以独立的运动从美术中分离出来。蒙德里安称为父亲的图形设计。他是一个很好的艺术家，但是他在现代广告中利用现代电网系统在广告、印刷和网络布局网格。 于1849年，在大不列颠亨利科尔成为的主要力量之一在设计教育界，该国政府通告设计在杂志设计和制造的重要性。他组织了大型的展览作为庆祝现代工业技术和维多利亚式的设计。 从1892年至1896年威廉?莫里斯凯尔姆斯科特出版社出版的书籍的一些最重要的平面设计产品和工艺美术运动，并提出了一个非常赚钱的商机就是出版伟大文本论的图书并以高价出售给富人。莫里斯证明了市场的存在使平面设计在他们自己拥有的权利，并帮助开拓者从生产和美术分离设计。这历史相对论是，然而，重要的，因为它为第一次重大的反应对于十九世纪的陈旧的平面设计。莫里斯的工作，以及与其他私营新闻运动，直接影响新艺术风格和间接负责20世纪初非专业性平面设计的事态发展。 谁创造了最初的“平面设计”似乎存在争议。这被归因于英国的设计师和大学教授Richard Guyatt，但另一消息来源于20世纪初美国图书设计师William Addison Dwiggins。 伦敦地铁的标志设计是爱德华约翰斯顿于1916年设计的一个经典的现代而且使用了系统字体设计。 在20世纪20年代，苏联的建构主义应用于“智能生产”在不同领域的生产。个性化的运动艺术在俄罗斯大革命是没有价值的，从而走向以创造物体的功利为目的。他们设计的建筑、剧院集、海报、面料、服装、家具、徽标、菜单等。 Jan Tschichold 在他的1928年书中编纂了新的现代印刷原则，他后来否认他在这本书的法西斯主义哲学主张，但它仍然是非常有影响力。 Tschichold ，包豪斯印刷专家如赫伯特拜耳和拉斯洛莫霍伊一纳吉，和El Lissitzky 是平面设计之父都被我们今天所知。 他们首创的生产技术和文体设备，主要用于整个二十世纪。随后的几年看到平面设计在现代风格获得广泛的接受和应用。第二次世界大战结束后，美国经济的建立更需要平面设计，主要是广告和包装等。移居国外的德国包豪斯设计学院于1937年到芝加哥带来了“大规模生产”极简到美国;引发野火的“现代”建筑和设计。值得注意的名称世纪中叶现代设计包括阿德里安Frutiger ，设计师和Frutiger字体大学;保兰德，从20世纪30年代后期，直到他去世于1996年，采取的原则和适用包豪斯他们受欢迎的广告和标志设计，帮助创造一个独特的办法，美国的欧洲简约而成为一个主要的先驱。平面设计称为企业形象;约瑟夫米勒，罗克曼，设计的海报严重尚未获取1950年代和1960年代时代典型。 从道路标志到技术图表，从备忘录到参考手册，增强了平面设计的知识转让。可读性增强了文字的视觉效果。 设计还可以通过理念或有效的视觉传播帮助销售产品。将它应用到产品和公司识别系统的要素像标志、颜色和文字。连同这些被定义为品牌。品牌已日益成为重要的提供的服务范围，许多平面设计师，企业形象和条件往往是同时交替使用。
Study on Project Cost Control of Construction Enterprises By: R. Max Wideman Abstract With the increasing maturity of construction market, the competition between construction enterprises is becoming fierce. The project profit is gradually decreasing. It demands that all construction enterprises enhance their cost control, lower costs, improve management efficiency and gain maximal profits. This paper analyses the existing problems on project cost control of Chinese construction enterprises, and proposes some suggestions to improve project cost control system. Key Words ：Construction enterprises, Project management, Cost control After joining the WTO, with Chinese construction market becoming integrated, the competition among architectural enterprises is turning more intense. Construction enterprises must continually enhance the overall competitiveness if they want to develop further at home and abroad construction market. Construction Enterprises basically adopt the "project management-centered" model, therefore, it is particularly important to strengthen project cost control. 1.The Current Domestic Project Cost Classification and Control Methods Cost refers to the consumption from producing and selling of certain products, with the performance of various monetary standing for materialized labor and labor-consuming. Direct and indirect costs constitute the total cost, also known as production cost or manufacturing cost. Enterprise product cost is the comprehensive indicator to measure enterprise quality of all aspects. It is not only the fund compensation scale, but also the basis to examine the implementation of cost plan. Besides, it can provide reference for product pricing According to the above-mentioned definition and current domestic cost classification, construction project cost can be divided into direct costs and indirect costs. Direct costs include material cost, personnel cost, construction machinery cost, material transportation cost, temporarily facility cost, engineering cost and other direct cost. Indirect costs mainly result from project management and company's cost-sharing, covering project operating costs (covering the commission of foreign projects), project's management costs (including exchange losses of
现有的太阳能自动跟踪控制器无外乎两种：一是使用一只光敏传感器与施密特触发器或单稳态触发器，构成光控施密特触发器或光控单稳态触发器来控制电机的停、转；二是使用两只光敏传感器与两只比较器分别构成两个光控比较器控制电机的正反转。由于一年四季、早晚和中午环境光和阳光的强弱变化范围都很大，所以上述两种控制器很难使大阳能接收装置四季全天候跟踪太阳。这里所介绍的控制电路也包括两个电压比较器，但设在其输人端的光敏传感器则分别由两只光敏电阻串联交叉组合而成。每一组两只光敏电阻中的一只为比较器的上偏置电阻，另一只为下偏置电阻；一只检测太阳光照，另一只则检测环境光照，送至比较器输人端的比较电平始终为两者光照之差。所以，本控制器能使太阳能接收装置四季全天候跟踪太阳，而且调试十分简单，成本也比较低。 电路原理
电路原理图如图1所示（点击下载原理图），双运放LM358与R1、R2构成两个电压比较器，参考电压为VDD（＋12V）的1/2。光敏电阻RT1、RT2与电位器RP1和光敏电阻RT3、RT4与电位器RP2分别构成光敏传感电路，该电路的特殊之处在于能根据环境光线的强弱进行自动补偿。如图2所示，将RT1和RT3安装在垂直遮阳板的一侧，RT4和RT2安装在另一侧。当RT1、RT2、RT3和RT4同时受环境自然光线作用时，RP1和RP2的中心点电压不变。如果只有RT1、RT3受太阳光照射，RT1的内阻减小，LM358的③脚电位升高，①脚输出高电平，三极管VT1饱和导通，继电器K1导通，其转换触点3与触点1闭合。同时RT3内阻减小，LM358的⑤脚电位下降，K2不动作，其转换触点3与静触点2闭合，电机M正转；同理，如果只有RT2、RT4受太阳光照射，继电器K2导通，K1断开，电机M反转。当转到垂直遮阳板两侧的光照度相同时，继由器K1、
光伏系统中蓄电池的充电保护IC电路设计 1.引言 太阳能作为一种取之不尽、用之不竭的能源越来越受到重视。太阳能发电已经在很多国家和地区开始普及，太阳能照明也已经在我国很多城市开始投入使用。作为太阳能照明的一个关键部分，蓄电池的充电以及保护显得尤为重要。由于密封免维护铅酸蓄电池具有密封好、无泄漏、无污染、免维护、价格低廉、供电可靠，在电池的整个寿命期间电压稳定且不需要维护等优点，所以在各类需要不间断供电的电子设备和便携式仪器仪表中有着广泛的应用。采用适当的浮充电压，在正常使用(防止过放、过充、过流)时，免维护铅酸蓄电池的浮充寿命可达12~16年，如果浮充电压偏差5%则使用寿命缩短1/2。由此可见，充电方式对这类电池的使用寿命有着重大的影响。由于在光伏发电中，蓄电池无需经常维护，因此采用正确的充电方式并采用合理的保护方式，能有效延长蓄电池的使用寿命。传统的充电和保护IC是分立的，占用而积大并且外围电路复杂。目前，市场上还没有真正的将充电与保护功能集成于单一芯片。针对这个问题，设计一种集蓄电池充电和保护功能于一身的IC是十分必要的。 2.系统设计与考虑 系统主要包括两大部分:蓄电池充电模块和保护模块。这对于将蓄电池作为备用电源使用的场合具有重要意义，它既可以保证外部电源给蓄电池供电，又可以在蓄电池过充、过流以及外部电源断开蓄电池处于过放状态时提供保护，将充电和保护功能集于一身使得电路简化，并且减少宝贵的而积资源浪费。图1是此Ic在光伏发电系统中的具体应用，也是此设计的来源。 免维护铅酸蓄电池的寿命通常为循环寿命和浮充寿命，影响蓄电池寿命的因
素有充电速率、放电速率和浮充电压。某些厂家称如果有过充保护电路，充电率可以达到甚至超过2C(C为蓄电池的额定容量)，但是电池厂商推荐的充电率是C/20~C/3。电池的电压与温度有关，温度每升高1℃，单格电池电压下降4 mV，也就是说电池的浮充电压有负的温度系数-4 mV/℃。普通充电器在25℃处为最佳工作状态；在环境温度为0℃时充电不足；在45℃时可能因严重过充电缩短电池的使用寿命。要使得蓄电池延长工作寿命，对蓄电池的工作状态要有一定的了解和分析，从而实现对蓄电池进行保护的目的。蓄电池有四种工作状态:通常状态、过电流状态、过充电状态、过放电状态。但是由于不同的过放电电流对蓄电池的容量和寿命所产生的影响不尽相同，所以对蓄电池的过放电电流检测也要分别对待。当电池处于过充电状态的时间较长，则会严重降低电池的容量，缩短电池的寿命。当电池处于过放电状态的时间超过规定时间，则电池由于电池电压过低可能无法再充电使用，从而使得电池寿命降低。 根据以上所述，充电方式对免维护铅酸蓄电池的寿命有很大影响，同时为了使电池始终处于良好的工作状态，蓄电池保护电路必须能够对电池的非正常工作状态进行检测，并作出动作以使电池能够从不正常的工作状态回到通常工作状态，从而实现对电池的保护。 3.单元模块设计 3.1充电模块 芯片的充电模块框图如图2所示。该电路包括限流比较器、电流取样比较器、基准电压源、欠压检测电路、电压取样电路和逻辑控制电路。 该模块内含有独立的限流放大器和电压控制电路，它可以控制芯片外驱动器，驱动器提供的输出电流为20~30 mA，可直接驱动外部串联的调整管，从
毕业论文外文文献翻译 毕业设计（论文）题目关于企业内部环境绩效审计的研究翻译题目最高审计机关的环境审计活动 学院会计学院 专业会计学 姓名张军芳 班级09020615 学号09027927 指导教师何瑞雄
最高审计机关的环境审计活动 1最高审计机关越来越多的活跃在环境审计领域。特别是1993-1996年期间，工作组已检测到环境审计活动坚定的数量增长。首先，越来越多的最高审计机关已经活跃在这个领域。其次是积极的最高审计机关，甚至变得更加活跃：他们分配较大部分的审计资源给这类工作，同时出版更多环保审计报告。表1显示了平均数字。然而，这里是机构间差异较大。例如，环境报告的数量变化，每个审计机关从1到36份报告不等。 1996-1999年期间，结果是不那么容易诠释。第一，活跃在环境审计领域的最高审计机关数量并没有太大变化。“活性基团”的组成没有保持相同的：一些最高审计机关进入，而其他最高审计机关离开了团队。环境审计花费的时间量略有增加。二，但是，审计报告数量略有下降，1996年和1999年之间。这些数字可能反映了从量到质的转变。这个信号解释了在过去三年从规律性审计到绩效审计的转变（1994-1996年，20％的规律性审计和44％绩效审计;1997-1999：16％规律性审计和绩效审计54％）。在一般情况下，绩效审计需要更多的资源。我们必须认识到审计的范围可能急剧变化。在将来，再将来开发一些其他方式去测算人们工作量而不是计算通过花费的时间和发表的报告会是很有趣的。 在2000年，有62个响应了最高审计机关并向工作组提供了更详细的关于他们自1997年以来公布的工作信息。在1997-1999年，这62个最高审计机关公布的560个环境审计报告。当然，这些报告反映了一个庞大的身躯，可用于其他机构的经验。环境审计报告的参考书目可在网站上的最高审计机关国际组织的工作组看到。这里这个信息是用来给最高审计机关的审计工作的内容更多一些洞察。 自1997年以来，少数环境审计是规律性审计（560篇报告中有87篇，占16％）。大多数审计绩效审计（560篇报告中有304篇，占54％），或组合的规律性和绩效审计（560篇报告中有169篇，占30％）。如前文所述，绩效审计是一个广泛的概念。在实践中，绩效审计往往集中于环保计划的实施（560篇报告中有264篇，占47％），符合国家环保法律，法规的，由政府部门，部委和/或其他机构的任务给访问（560篇报告中有212篇，占38％）。此外，审计经常被列入政府的环境管理系统（560篇报告中有156篇，占28％）。下面的元素得到了关注审计报告：影响或影响现有的国家环境计划非环保项目对环境的影响;环境政策;由政府遵守国际义务和承诺的10％至20％。许多绩效审计包括以上提到的要素之一。 1本文译自：S. Van Leeuwen.(2004).’’Developments in Environmental Auditing by Supreme Audit Institutions’’ Environmental Management Vol. 33, No. 2, pp. 163–1721
（ 二 〇 一 二 年 六 月 外文文献及翻译 题 目： About Buiding on the Structure Design 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(建筑工程方向) 班 级：土木08-4班 指导教师：
英文原文： Building construction concrete crack of prevention and processing Abstract The crack problem of concrete is a widespread existence but again difficult in solve of engineering actual problem, this text carried on a study analysis to a little bit familiar crack problem in the concrete engineering, and aim at concrete the circumstance put forward some prevention, processing measure. Keyword:Concrete crack prevention processing Foreword Concrete's ising 1 kind is anticipate by the freestone bone, cement, water and other mixture but formation of the in addition material of quality brittleness not and all material.Because the concrete construction transform with oneself, control etc. a series problem, harden model of in the concrete existence numerous tiny hole, spirit cave and tiny crack, is exactly because these beginning start blemish of existence just make the concrete present one some not and all the characteristic of quality.The tiny crack is a kind of harmless crack and accept concrete heavy, defend Shen and a little bit other use function not a creation to endanger.But after the concrete be subjected to lotus carry, difference in temperature etc. function, tiny crack would continuously of expand with connect, end formation we can see without the
外文翻译文献 中英文对照资料外文翻译文献 光伏逆变器的发展及优势 结构与工作原理 逆变器是一种由半导体器件组成的电力调整装置，主要用于把直流电力转换成交流电力。一般由升压回路和逆变桥式回路构成。升压回路把太阳电池的直流电压升压到逆变器输出控制所需的直流电压；逆变桥式回路则把升压后的直流电压等价地转换成常用频率的交流电压。逆变器主要由晶体管等开关元件构成，通过有规则地让开关元件重复开 -关（ ON-OFF），使直流输入变成交流输出。当然，这样单纯地由开和关回路产生的逆变器输出波形并不实用。一般需要采用高频脉宽调制（ SPWM），使靠近正弦波两端的电压宽度变狭，正弦波中央的电压宽度变宽，并在半周期内始终让开关元件按一定频率朝一方向动作，这样形成一个脉冲波列（拟正弦波）。然后让脉冲波通过简单的滤波器形成正弦波。
逆变器不仅具有直交流变换功能，还具有最大限度地发挥太阳电池性能的功能和系统故障保护功能。归纳起来有自动运行和停机功能、最大功率跟踪控制功能、防单独运行功能（并网系统用）、自动电压调整功能（并网系统用）、直流检测功能（并网系统用）、直流接地检测功能（并网系统用）。这里简单介绍自动运行和停机功能及最大功率跟踪控制功能。 1、自动运行和停机功能 早晨日出后，太阳辐射强度逐渐增强，太阳电池的输出也随之增大，当达到逆变器工作所需的输出功率后，逆变器即自动开始运行。进入运行后，逆变器便时时刻刻监视太阳电池组件的输出，只要太阳电池组件的输出功率大于逆变器工作所需的输出功率，逆变器就持续运行；直到日落停机，即使阴雨天逆变器也能运行。当太阳电池组件输出变小，逆变器输出接近 0 时，逆变器便形成待机状态。 2、最大功率跟踪控制功能 太阳电池组件的输出是随太阳辐射强度和太阳电池组件自身温度（芯片温度）而变化的。另外由于太阳电池组件具有电压随电流增大而下降的特性，因此存在能获取最大功率的最佳工作点。太阳辐射强度是变化着的，显然最佳工作点也是在变化的。相对于这些变化，始终让太阳电池组件的工作点处于最大功率点，系统始终从太阳电池组件获取最大功率输出，这种控制就是最大功率跟踪控制。太阳能
Unit1 renewable Energy Commercialization Introduction 可再生能源商业化涉及可再生能源三代技术的部署要追溯到100多年,见图1.1和图1.2。第一代技术已经成熟和经济竞争包括，生物量、水力发电、地热能和热。第二代市场化技术目前正在部署,其中包括太阳能加热,光伏发电,风力发电、太阳能热发电站和现代形式的生物能源。第三代技术需要继续努力研究和开发(研发)为了在全球范围内,做出巨大的贡献。先进的生物质气化技术、包括干热岩地热发电,海洋能发电. 有一些非技术性的障碍广泛存在于可再生能源,而且往往是公共政策和政治领导,帮助解决这些障碍,推动可再生能源技术的更广泛的利用。2010年,98个国家制定自己的可再生能源期货目标和制定广泛的公共政策来提倡可再生能源。而且气候变化的问题推动了可再生能源行业的增长。领先的可再生能源公司包括第一太阳能、Gamesa、通用电气能源，q - cells,锋利太阳能、西门子、Sunopta尚德和维斯塔斯。 可再生能源的总投资在2010亿年达到211亿美元,高于在2009年的160亿美元。2010年投资最多的国家是中国、德国、美国、意大利和巴西。预计可再生能源行业的持续增长和与许多其他行业相比在2009年经济危机中促销政策能帮助天气行业。 美国总统奥巴马在2009年美国复苏与再投资法案中包括再投资700亿美元的支出和抵免税收对清洁能源和相关的运输计划。清洁科技表明,清洁能源的商业化已经帮助世界各国摆脱2009年的全球金融危机。经济分析师预计市场可再生能源(天然气)收益在2011年日本核事故直接影响了在全球范围内可再生能源行业中大约300万个工作岗位,其中大约一半是生物燃料产业。根据国际能源署2011年的推测, 在50年内太阳能发电机可能产生世界上大多数的电力,显著降低有害温室气体的排放。 Lesson1 overview Rationale for renewables 气候变化、污染和能源安全是当前最严重的问题和解决他们需要能量基础设施的重大改变。可再生能源技术贡献者能源供应组合至关重要,因为他们为世界能源安全、减少对化石燃料的依赖,为减轻温室提供机会。破坏大气的化石燃料正在被清洁，对大气稳定，用之不绝的能源取代: 煤炭、石油和天然气,风能,太阳能,地热能也在进行中。在旧经济时期,能源是由可燃油,煤炭、或自然导气的碳排放来定义我们的经济。新能源经济利用来自太阳的能量的风能,和来自地球内部的热量本身。 应用材料公司进行的一项2010年的调查显示,三分之二的美国人认为太阳能技术应该在会议上发挥更大的作用在国家的能源需求时。此外,“四分之三的美国人认为增加可再生能源和减少美国对外国石油的依赖的能源优先”。据调查,“67%的美国人愿意花更多的钱为他们的每月帐单如果他们的公用事业公司增加了使用可再生能源”。 Three generations of technologies 可再生能源这个术语涵盖了数量的来源和技术商业化的不同阶段。国际能源署(IEA)定义了三代的可再生能源技术,可追溯到100多年。 第一代技术从工业革命开始出现19世纪末,包括水力发电、生物质燃烧、地热能和热。这些技术被非常广泛的使用。 第二代技术包括太阳能供热和制冷,风能。现代形式的生物能,太阳能光伏发电。这些技术现在已经进入市场的研究、开发和示范。自1980年代以来(研发和实证)投资。初始投资是受能量安全问题与1970年代的石油危机限制,但这些技术的持久魅力,至少在某种程度上会有环境效益。许多的技术反映出在材料方面有重大的进步。
废弃混凝土再生新技术探索 【摘要】本文对目前废弃混凝土再生技术的研究做了论述,并指出了其中存在的一些问题。结合混凝土各组成部分的结构特点,提出了通过低温煅烧对废弃混凝土综合利用的新方法。在750℃温度条件下煅烧1h,可以实现水泥浆与骨料的分离。脱水后的水泥浆可以重新获得水化活性。得到的混凝土骨料可以满足使用要求。 【关键词】废弃混凝土;再生技术;煅烧;水化活性;压碎指标 【中图分类号】TU352·8【文献标识码】A【文章编号】1001-6864(2009)09-0004-02 国家“十五计划”纲要指出:“坚持资源开发与节约并举,把节约放在首位,法保护和合理使用资源,提高资源利用率,实现永续利用。推进资源综合利用技术研究开发,加强废旧物资回收利用,加快废弃物处理的产业化,促进废弃物转化为可用资源。”保护环境、节约能源、减少废料、以持续的方式使用可再生资源是可持续发展战略的重要内容。建材工业是典型的基础原料工业,在国民经济发展中具有重要作用。建材工业又是典型的资源、能源消耗型工业,在其快速发展的同时,面临着资源、能源的过度消耗和环境的严重污染。建筑和建材行业的根本出路就是走可持续发展的道路[1]。起初,我国对混凝土的利用仅是简单的破碎充当再生粗骨料,这种生产的再生骨料性能与天然粗骨料的性能存在一定差异,主要表现在密度低、吸水率高、压碎指标大,表明再生骨料的空隙率高,强度低,这主要是由于其表面附着有大量水泥砂浆及在破碎过程中引入一定量的微裂纹的缘故[2],生成的混凝土性能低,耐久性、抗冻融、抗腐蚀能力差。研究者根据再生骨料再利用过程中存在的问题,对再生骨料进行了物理、化学改性以及整形改性。如朱崇绩等通过整形除去再生骨料表面的砂浆,使颗粒变得光滑,需水量降低,使所配制的混凝土收缩降低,但仍高于天然骨料混凝土[3]。没有解决再生骨料中微裂纹带来的弊端。目前有研究者对废弃混凝土进行了综合利用研究,通过筛分获得砌筑砂浆或进步筛分生产具有水化活性的再生水泥。如孙荣光等[4]对旧水泥浆高温处理后的再水化胶凝特性研究,得出再生水泥具有再水化的能力,同时生成C-S-H凝胶、Aft和CH等物质,说明水化产物结构相同,但由于大量脱水相的存在使水化速度快。余睿等[5]通过对水泥浆的研究得出石膏和粉煤灰组成改性剂能延长活化水泥浆的初凝时间,增强其抗压强度,但不能减少活化水泥浆的标准稠度需水量。由于易水化的水泥石脱水需要时间,所以煅烧时间和脱水温度对再生水泥性能不容忽视。 1．废弃混凝土裂解温度确定 混凝土是由水泥、粗细集料、矿物掺合料等加水拌合,经水化硬化而形成的一种微观不均匀,宏观均匀的人造石。废弃混凝土在低温煅烧时的温度由水泥脱水温度与石灰石分解温度共同决定。 1·1水泥水化产物脱水温度 文献认为,含水矿物中普通吸附水的脱水温度一般为100~110℃,存在于层状硅酸盐结构中的层间水或胶体矿物中的胶体水多数要在200~300℃以内脱水,个别要在400℃以内脱水;架状结构的硅酸盐结构水则要在400℃左右才大量脱出。结晶水在不同结构中的矿物中结合程度不同,其脱水温度也不同。结构水是矿物中结合最牢的水,脱水温度较高,一般要在450℃以上才脱水[5]。为了确定废弃混
学号： 10447425 X X 大学 毕业设计（论文）外文翻译 （2014届） 外文题目 Developments in excavation bracing systems 译文题目开挖工程支撑体系的发展 外文出处 Tunnelling and Underground Space Technology 31 (2012) 107–116 学生 XXX 学院 XXXX 专业班级 XXXXX 校内指导教师 XXX 专业技术职务 XXXXX 校外指导老师专业技术职务 二○一三年十二月
开挖工程支撑体系的发展 1.引言 几乎所有土木工程建设项目（如建筑物，道路，隧道，桥梁，污水处理厂，管道，下水道）都涉及泥土挖掘的一些工程量。往往由于由相邻的结构，特性线，或使用权空间的限制，必须要一个土地固定系统，以允许土壤被挖掘到所需的深度。历史上，许多挖掘支撑系统已经开发出来。其中，现在比较常见的几种方法是：板桩，钻孔桩墙，泥浆墙。 土地固定系统的选择是由技术性能要求和施工可行性（例如手段，方法）决定的，包括执行的可靠性，而成本考虑了这些之后，其他问题也得到解决。通常环境后果（用于处理废泥浆和钻井液如监管要求）也非常被关注（邱阳、1998）。 土地固定系统通常是建设项目的较大的一个组成部分。如果不能按时完成项目，将极大地影响总成本。通常首先建造支撑，在许多情况下，临时支撑系统是用于支持在挖掘以允许进行不断施工，直到永久系统被构造。临时系统可以被去除或留在原处。 打桩时，因撞击或振动它们可能会被赶入到位。在一般情况下，振动是最昂贵的方法，但只适合于松散颗粒材料，土壤中具有较高电阻（例如，通过鹅卵石）的不能使用。采用打入桩系统通常是中间的成本和适合于软沉积物（包括粘性和非粘性），只要该矿床是免费的鹅卵石或更大的岩石。 通常，垂直元素（例如桩）的前安装挖掘工程和水平元件（如内部支撑或绑回）被安装为挖掘工程的进行下去，从而限制了跨距长度，以便减少在垂直开发弯矩元素。在填充情况下，桩可先设置，从在斜坡的底部其嵌入悬挑起来，安装作为填充进步水平元素（如搭背或土钉）。如果滞后是用来保持垂直元素之间的土壤中，它被安装为挖掘工程的进行下去，或之前以填补位置。 吉尔- 马丁等人（2010）提供了一个数值计算程序，以获取圆形桩承受轴向载荷和统一标志（如悬臂桩）的单轴弯矩的最佳纵筋。他们开发的两种优化流程：用一个或两个直径为纵向钢筋。优化增强模式允许大量减少的设计要求钢筋的用量，这些减少纵向钢筋可达到50％相对传统的，均匀分布的加固方案。 加固桩集中纵向钢筋最佳的位置在受拉区。除了节约钢筋，所述非对称加强钢筋图案提高抗弯刚度，通过增加转动惯量的转化部分的时刻。这种增加的刚性可能会在一段时间内增加的变形与蠕变相关的费用。评估相对于传统的非对称加强桩的优点，对称，钢筋桩被服务的条件下全面测试来完成的，这种试验是为了验证结构的可行性和取得的变形的原位测量。 基于现场试验中，用于优化的加强图案的优点浇铸钻出孔（CIDH）在巴塞罗那的几个非对称加强桩的施工过程中观察到混凝土桩沿与测得的变形的结果在常规和描述优化桩。实验证据表明，非对称地增强桩变形比观察到在常规增强那些小。两桩类型（对称和非对称）具有相同的直径，并设计为抵抗基于极限强度设计相同的弯曲力矩;离散杆的尺寸和使用的条全数字的，导致类似的名义抗弯强度。