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Automatic Position Determination
1 Position Determination
The traditional method for the direct determination of position has been by astronomical observation. The relative positions and movements of the stars as well catalogued and so with a combination of altitude, direction and time observations to the stars, the position in terms of latitude and longitude of a ground station can be calculated. There if less call for direct position determination nowadays since most countries are covered by a primary horizontal control scheme, and the absolute position of any new local survey word can be established by including a national reference point in the local survey.
In very remote areas, or where the terrain is totally unsuitable for the classic survey methods of triangulation and traverse, there is, however, a need for direct position determination. For the majority of this work, visual observation to the stars has been replaced by electromagnetic measurements to or from artificial earth satellites. In addition, the relative positions of survey stations can be determined directly by inertial techniques originally developed for aircraft navigation.
1.1 Inertial Positioning
A pair of gyros are incorporated in a position fixing device known as the Auto-Surveyor manufactured by Litton Systems. It has originated from an aircraft navigation system, which was developed for military applications into its present three-dimensional survey system. ‘Hardware’ consists of (i)the inertial measuring unit, (ii)a computer ,(iii)a cassette recorder,(iv)a display and control unit and (v) the power supply .These items can be placed anywhere within a road vehicle or helicopter providing that the operator is close to (iv).
The measuring unit contains a gyro-stabilized platform with two air-bearing gyroscopes in four gimbal mountings which keep its three orthogonal axis oriented in space in a north-east=downwards relationship . Each axis also has a sensor-torquer type of acclerometer which defines acceleration in the particular direction via a quantitizer system feeding the computer .This is pre-programmed to compute the survey as it is carried out and to control the system (see Fig.1)
Before staring the survey an alignment drill carried out at the origin station. This is said to have a duration of about one hour (that for the survey is restricted to some four hours or so) and the platform levels itself with respect to the local vertical and aligns its nothing axis with the local meridian so that the accelerometers are in the directions of north, east and down. Simultaneously the computer monitors the biases of the system and evaluates the initial conditions for a Kalman filter enables an evaluation of the
performance of the system by comparison of the errors arising during the survey to a priori data relating to the statistical nature of errors which navigation instruments are likely to contain.
When the alignment is complete the known coordinates and elevation of the station are fed in by the operator and the traverse can begin. The orthogonal movements are sensed by the accelerometers and, at intervals of sixteen milliseconds, the signals to the computer are doubly integrated into distances of displacement with respect to the origin. In the Auto-Surveyor ‘z-increments’ accumulate as elevation differences, whilst the other two increments are used to compute values of geodetic latitude and longitude on the pre-programmed reference spheroid. The computer also directs the platform gimbal torques to place the platform tangential to the spheroid with the north axis correctly oriented.
At approximately four minute intervals the vehicle is halted a ‘zero velocity updating’ is carried out. This takes about thirty seconds and the platform is re-leveled, with respect to local vertical, and effectively resets ’vertical zero‘. As mentioned above, previous calculations and platform torquing are with respect to the reference spheroid so that the amount of torque used for the re-leveling is a measure of the directional change of deviation from the vertical. Since the vehicle is stationary, the accelerometers should read zero as should the velocities by mtegration so that when the Kalman filter scrutinizes these values it can establish accelerometer errors due to their drift, which is non-linear, and it uses the velocity errors to establish the rate of change of drift; precise integration is not possible after four minutes due to that drift. Platform re-leveling takes place after the adjustment.
The survey now continues with successive updating stops and also with halts at the survey stations where the same process occurs. At the terminal station known coordinates and elevations are entered as updating information and a zero velocity update is carried out; the Kalman filter carries out a smoothing adjustment data and results of the smoothing are registered on the recorder.
Traverse lines are normally measured in two directions, occupying the same stations , discrepancies then indicating effects of gyrodrift on platform alignment .Standard errors of ±0.20 m in position of points at 10 km separation are achievable with a similar value for heighting when a road vehicle is used.
Ferranti manufacture a corresponding system in the UK, and reference can be made to a report in the New Civil Engineer, 17 January 1980, on its value to the highway engineer. This report refers specifically to their Inertial Road Surveyor although it indicates that systems for land surveys, borehole surveys and underwater surveys are available too.
2 GPS IN NA VIGATIONAL APPLICATIONS
2.1 INTRODUCTION
Global Positioning System (GPS) has for several years been a buzzword for professionals in many fields including surveying, geodesy, GIS, meteorology, and geodynamics. The reason for this GPS wonder perhaps lies in the superior capability of GPS: it offers solutions to many problems that we could not or felt difficult to solve, and also enables us to do many things better than before. Navigation is one of these things, which has been greatly changed from the development of GPS.
This paper will provide an overview of GPS as applied to navigation. It will first describe briefly the principles of GPS .The different GPS based positioning methods in navigation will then be discussed, followed by an review of GPS based systems for air, land and marine navigation.
2.2 PRINCIPLES OF GPS POSITIONING
GPS is a satellite based passive positioning system that was initially designed primarily for military use .It was developed and has been maintained by the United States Department of Defense (US DoD). The system is now used by both the military and civilian users to obtain high accuracy position, velocity and
time information, 24 hours a day, under all weather conditions, and anywhere in the world. The system was 1993 and full operational capability (FOC) in April 1995.
2.2.1 The Components of GPS
One common way to look at GPS is to resolve it into three segments:
The space segment refers to GPS satellites that are orbiting at an altitude of about 20,200 km above the earth surface. The full operational capacity of GPS is achieved with 24 active satellites. There are currently 27 operational satellites, three of that are the active spares that can be used as replacements when the active satellites are out of services. The key components in satellite are the antennas sending and receiving signals, two large wings covered with solar cells to generate power for the satellite to consume, and atomic clocks that are accurate to about 1 second in 3,000,000 years.
The control segment consists of 5 monitor stations, 3 ground antennas, and 1 master control station. The monitor stations passively track all satellites in view, accumulating ranging data. The tracked data are processed at the master control station to determine satellite orbits and to update each satellite’s Navigation Message. The updated information is transmitted to each satellite via the ground antennas.
The user segment is anybody who has a GPS receiver. The surveyors, the navigators and the GIS data collectors are examples of the users.
The signals that GPS satellites send out consist of two codes, the coarse acquisition (C/A) code and the precise (P) code, and a Navigation Message. The GPS codes are just like a series of 1’s and 0’s that are arranged into certain sequences, Figure 1. The C/A code is used for the standard positioning service (SPS) available to all users. The service offers a positional accuracy of about 100 m horizontally and 156 m vertically at the 95% probability level. The P code is used for the Precise Positioning Service (PPS) and can bi accessed only by authorized users such as the US military and its allies. The service provides a positional accuracy of about 15 m horizontally and 25 m vertically at the 95% probability level.
The GPS Navigation Message contains such information as the orbital elements of the satellites, clock behavior, and an almanac that gives the approximate data for each active satellite. Two carrier frequencies on L-band, L1 and L2 are used to carry the signals described above. L1 has a wave-length of about 19 cm (1575.42MHz) and L2 a wave-length of about 24 cm (1227.60MHz). Both L1 and L2 are microwave frequencies and can penetrate the atmosphere. L1 carries both the C/A and the p codes and L2 the p code only. The Navigation Message is carried on both of the two frequencies.
To the more sophisticated users such as the surveyors, positioning using the code information cannot fulfill their accuracy requirements, say at the centimeter or millimeter level. In this case, the L1 or L2, or both L1 and L2 carrier phases are also observed and used for positioning.
2.2.2 The Working Principles of GPS
GPS measures positions by measuring distances. GPS satellites have known orbits and
therefore known positions at any instant time. Therefore, if the distances to three or more GPS satellites can be measured from a point anywhere on near the earth surface, the three-dimensional position of the point can bi calculated, Figure 2.
The distances between the point and the satellites are determined either using the code or
the carrier phase observations. The same GPS codes are generated at the same time by both the satellites and the GPS receiver. When the receiver receives the code information from the satellites, it correlates the signals it generates and those received from the satellites, Figure 3, which can determine the time that takes for the GPS signal to travel from a satellite to the receiver. The time can then be used to calculate the distance.
Figure3. Time measurement by code correlation
Figure4. Carrier waves and phase measurement
As the clock of the receiver has usually a much lower accuracy than those on a GPS
satellite, the clock time is in practice commonly considered as an unknown parameter which is solved together with the position of the receiver point. In this case, signals from at least four GPS satellites are required, as there are four unknown values to be solves for.
When carrier phase observations are used in GPS positioning, the distance between a
receiver point and a satellite is determined using.
Distance = λλ?+N (1)
Where λ is the wavelength of the carrier wave; N is the whole wave numbers counted
from a satellite to the receiver and λ? is the length that is shorter than one wavelength, Figure4. λ? is determined directly from the phase measurements. N is the integer ambiguity and is usually solved for based on continuous phase observations over some extended time.
2.2.3 Pros and Cons of GPS
Some general points on the advantages of GPS are given here only. First, it covers the whole globe spatially. Hence the word ‘Global’ in is its name, and continuously in time for 24 hour a day. Second, the system offers high positioning accuracy at an affordable price to the user. Besides, GPS is convenient to use in many applications.
GPS also has its disadvantages. Perhaps the biggest problem that it has is the requirement of line of sight to GPS satellites. GPS signals can penetrate the atmosphere but not any solid objects such as buildings, trees, and mountains. This requirement seriously limits the use as buildings, trees, and mountains. This requirement seriously limits the use of GPS in environments such as dense urban areas and underground. Another problem with GPS is the multipath effects that contribute to significant errors when a receiver is surrounded by smooth reflective surfaces.
3 GPS BASED POSITIONING METHODS IN NA VIGATION
GPS was designed primarily as a tool for navigation. It has been successfully applied for the navigation of vehicles such as cars, ships and airplanes, as well as for the guidance of weaponry objects such as missiles. This section will look at the different positioning methods of using GPS in navigation.
3.1 Single Receiver Positioning
The simplest way to used GPS for navigation is to carry a GPS receiver whenever you go. The receiver can offer in real-time the SPS positioning accuracy, that was discussed earlier, as long as signals from four or more GPS satellites can be received. Since such an application is very basic, almost any commercial GPS receivers on the market can be used for this purpose. Many of the receiver units cost less than US$100. This simple GPS positioning method is used very commonly for recreational activities such as hiking and fishing, Fieldwork in remote areas such as in the desert or forest, and travel on the sea.
3.2 Differential GPS (DGPS) Positioning
If the positioning accuracy described above is insufficient, an easy and affective way to increase the accuracy is to use differential GPS. In this operation mode, two GPS receivers are required, and the other carried around to where the position needs to be determined. In this case, the first receiver is called the reference station and the second the roving station.
If the user is close enough to the reference station, various GPS errors, such as the effect of the atmosphere, are very similar for both of the two stations. The reference station can be used to determine the errors in the three coordinate components. Corrections can be worked out for the position of the roving station based on the errors determined at the reference station. The positioning accuracy can be greatly improved by doing this ‘differential’operation. DGPS technique has been repeatedly demonstrated to achieve a positioning accuracy of 2 to 5m over baselines up to 1,000 km.
If real-time positioning is required, a data communication link between the two stations is required. A common approach is to use a pair of radios if the distance between the two stations is short, say within a few kilometers. For distances up to a few hundred kilometers, a broadcasting station can also be used to send the correction messages to the entire designated area. For example, Hong Kong has established a permanent GPS reference station on its Kau Yi Chau island. A transmitter is used to broadcast correction messages to an area of 500 km in diameter which covers the entire Hong Kong region. The claimed accuracy of the system is within 1 m.
The simple differential operation described above has relatively limited coverage, and is restricted by the coverage of the terrestrial communication system. Besides, the positioning accuracy decreases as the separation communication system. Besides, the positioning accuracy decreases as the separation between the user and the reference station increases. A technique called Wide Area Differential GPS (WADGPS) can be used to overcome the problems of the simple differential method. WADGPS uses a number of GPS reference stations to cover a wide area such as a whole country or continent. The GPS positioning errors are separately modeled and applied to the roving user station in a way that breaks the position dependence. Therefore the limitation in the navigation accuracy due to the user-reference station separation can be largely eliminated. Positioning accuracy of about 2 m and 3 m for
the horizontal and the height components respectively is achieved over base-lines ranging from 2,000 km to 3,500 km. The limitation in the coverage of the data links is also overcome by using geostationary communication satellites.
3.3 GPS Aided with Additional Sensors and Information
As said above, the requirement of direct line of sigh to GPS satellites makes it very difficult to use GPS in restricted areas such as high rise cities. For example, recent tests have shown that only about 30 percent of Hong Kong can receive signals from four or more GPS satellites. One way to solve the problem is to aid GPS with sensors such as compasses, odometers, inertial navigation systems (INS), which basically use gyros and accelerometers to the determination of positions, or additional information such as existing maps and databases.
Pseudolite, a pseudo-satellite as its name implies, is a device that can transmit GPS-like signals, A pseudolite can be placed at strategic locations such as on a tall building at a road intersection to transmit signals to nearby areas. The signals form a pseudolite can be treated in the same way as those from a real satellite.
GPS can also be used in combination with GLONASS (Global Navigation Satellite System), a system developed and maintained by Russia. The design and working principles of GLONASS are to certain extent similar to GPS. Efforts have been made by both researchers and instrument manufacturers to integrate the two systems to achieve better positioning accuracy and especially better satellite coverage in difficult environments. Receivers capable of receiving signals from both GPS and GLONASS satellites have been developed. A currently undergoing international GLONASS Experiment (IGEX-98) campaign organized by IAG, IERS,IGS, and ION is expected to establish a global network and bring research and international collaboration together.
The system integrity and future continuity of GLONASS has always been a concern, especially when the number of GLONASS satellites in space has dropped dramatically in 1997-1998.
The accuracy of differential GPS+GLONASS has been reported to be better than 0.5m
4 GPS BASED NA VIGATION SYSTEMS
Various GPS based navigation systems have been developed. This section will take a brief look at these and the basic requirements for land, air and marine navigation.
4.1 Airplane Navigation
It is understandable that navigation has different requirements under different circumstances. There are however some general considerations when designing different navigation systems, which are the accuracy, availability, continuity and integrity of the systems.
Although GPS and GLONASS combined provide very good positioning capability, they still however, when used alone, cannot meet the criteria as a sole means for navigation in aircraft navigation and landing guidance, or for safety-critical use in the marine and land environment. To meet these requirements, the GNSS-1 and GNSS-2(GNSS also comes from Global Navigation Satellite System) have been proposed. GNSS-1 is a satellite navigation system having GPS and/or GLONASS as backbone, augmented by other techniques. GNSS-1 is expected to meet the requirement for sole means of navigation up to non-precision approach and Cat 1 precision approach. GNSS-2 is the second generation satellite navigation system, which can meet all users requirements, independent of any other means of radio navigation. Though the system architecture of GNSS-2 has not been defined yet, its design goal is to provide sole means use for Category Ⅲ2b precision approach for landing.
The following are some of the developments in the scope of GNSS-1:
European Geostationary Navigation Overlay Service (EGNOS)
In Europe, a Tri-Partite Group made up of the European Organization for the Safety of Air Navigation (EUROCONTROL), the European Space Agency (ESA) and the European Commission (EC) jointly manages the EGNOS. The EC is responsible for institutional and policy issues and funding. EUROCONTROL defines the user requirements and is also involved in the test and validation phase of the system development. ESA manages the development of EGNOS within GNSS-1.
The coverage of EGNOS will be the footprint of Inmarsat Atlantic Ocean Regions East (AORE) and Indian Ocean Regions (IOR) as EGNOS uses these satellites as core transponder of the system. EGNOS is planned to reach its Initial Operational Capability, (IOC) in 1999and Final Operational Capability (FOC) in 2001. FOC is intended to meet sole-means requirements for en-route to Cat-I.
EGNOS will include GPS/GLONASS. GPS-like ranging system, wide area differential systems, ranging and integrity monitoring stations (RIMS), and geostationary integrity channel. When the Final Operational Capability (FOC) is declared the use of GPS/(GLONASS)/EGNOS/RAIM(Receiver Autonomous Integrity Monitoring) as sole means of navigation for up to Cat-I service shall be reached.
Wide Area Augmentation System (WAAS)
WAAS has been developed by the US Federal Aviation Administration (FAA). The ground network of the system includes 25 reference stations and 2 master stations providing differential and ionospheric corrections for improved accuracy. To achieve the various requirements of all phases of flight up to Cat-I, WAAS will also broadcast integrity messages
and additional GPS-like signal, beside the GPS differential corrections. The initial supplemental service, phase I of the system, has been scheduled for September 2000.
The WAAS aims at providing service for precise up to Cat-I. Local Area Augmentation Sys-tern(LAAS), which is similar in principle to WAAS but with a smaller area of coverage and higher positioning accuracy, will be employed for more stringent requirements of Cat-II/III precise approaches.
MTSAT Satellite Based Augmentation System (MSAS).
The Japanese Multi-functional Transport Satellite (MTSAT) Satellite Based Augmentation System (MSAS) is developed by the Japan Civil Aviation Bureau (JCAB) to support sole means navigation services for en-route to precision approach phases of flight. The first MTSAT is scheduled to be launched in 1999. Initial phase I (Cat-I) of the system is to be completed by 2001 and the final MSAS capability (CAT-II/III) is scheduled at 2005.
MASA in designed to provide Air Traffic (ATS) and meteorological mission. The system configuration is similar to the US WAAS. Consisting of ground network for broadcasting integrity and correction data and to provide additional GPS-like ranging system from geostationary satellite for improving availability and continuity.
The development of GNSS-2 has to consider institutional issues regarding the ownership, control and interoperability of the systems. With the consent of the ICAO (International Civil Aviation Organization) members, an interoperability working group has been set up and held its first meeting on July 1998 to discuss these issues. The interoperability demonstration for WAAS/EGNOA and WAAS/MSAS has been scheduled.
4.2 Land Vehicle Navigation
Land vehicle navigation systems need basically to provide information on, for example, the real-time position of the vehicle, and the shortest route to travel from one place to another or the route that takes the shortest time to travel. A complete navigation system is also supplemented by real-time display of the position of the vehicle on a map. Besides, at a central control station, a wireless data communication link is also required between each vehicle and the control station.
Intelligent Transport System (ITS) is an area of interests to many researchers as well as government transport departments. Beside the functionality of a basic land vehicle navigation system discussed above, an ITS may also include features such as automatic toll paying, intelligent control of traffic signals, etc.
The block of satellite signals by objects such as tall buildings, bridges, pedestrians, and surrounding vehicles is a major problem for satellite based land vehicle navigation ,especially in dense and high rise cities like Hong Kong ,Therefore, it is often necessary to supplement a satellite based positioning system with additional sensors such as compasses, odometers and INS. To achieve the required positioning accuracy in difficult areas while keeping the cost of the navigation system low is still an area of research.
4.3 Marine Navigation
The foremost requirement of a marine navigation system is to provide information on the position and direction of a ship when traveling on an open sea. It is also necessary Marine navigation can use a single GPS receiver, DGPS or the more sophisticated systems such as a GNSS de-pending on the navigational requirements.
5 CONCLUSIONS
In this paper , an introduction to GPS has been given ; various GPS-based positioning methods , including using a single GPS receiver , differential GPS, GPS aided with additional sensors and information , were discussed ;an overview of the development f GPS based navigation technology has been given; and some existing systems for air , land and marine navigation have also been briefly reviewed .
GPS is a new and powerful tool for many positioning applications such as surveying and navigation. It offers an unprecedented coverage both spatially and in time. The system is easy to apply and provides a high positioning accuracy at a relatively low cost to the end user. The major disadvantages of GPS include the requirement of line of sight to GPS satellites and multipath errors.
It seems clear that, to provide safer, more efficient and less costly means of navigation services, satellite-based navigation system will be an integrated system consisting of different sensors and technologies and it will provide global coverage and interoperability with integrity.
自动定位技术
1 定位技术
传统的直接定位是依靠天文学上的观测。恒星的相对位置和运动可以很好的加以分类，所以结合它们的高度、方向、时间的观测，有关地面测站的经纬度可以被计算出来。如今对直接定位的需求较少，因为大多数国家已经建立了基本水平控制网，对于包括一个国家基准点的任一新的局部测量，测区中的绝对位置都能被确定。
在那些非常偏僻的地区，或者那些完全不适合三角测量和导线测量方法的地区而
且又需要进行直接定位，大多数这些工作对可见恒星的观测已经被电磁测量或通过人造卫星观测所替代。另外，对测站的相对位置能直接被惯性技术所测定，该技术最被发展成为航天导航技术。
惯性定位
它起源于早期的军事应用导航系统，目前发展成为一个三维测量系统，其硬件设施包括（1）惯性测量单元；（2）一台计算机；（３）一台记录装置；（４）一台显示和控制单元；（５）能量供应装置。这些可被安装于公路交通工具或直升飞机上，只要显示和控制装置接近操作人员。
惯性测量单元包括一个陀螺稳定平台，其中在四个平衡环的支撑平台上有两个气承陀螺仪，它将保持空间东北方向的三个轴间的垂直关系。每一轴上均有一个加速计的感应转矩，它将通过连接计算机中的量化系统确定在特殊方向上的加速度。当它工作时，通过预编程序来计算并控制系统，如图１。
图1
在开始测量前，一个定位钻头将在初始测站定位，通常需要一个小时之久（对于一些严格的测量则需要4个或更多小时）。其自身的水准平台将与当地铅垂线垂直并且通过极点平行于指北轴，如此则加速计将向着北东及垂直向下方向，同时计算机监测器这一主要系统将通过卡尔曼滤波程序估计初始条件，这一程序包括调整输出目的软件，卡尔曼滤波通过对比在测量过程中产生的误差加强对整个系统过程的评估，从而优化那些导航仪器中可能包含的固定误差。
当定位完成后，测量员存入已知点的坐标及测站的高度，同时开始导线测量。垂直方向的运动通过加速计感知，在16毫妙的瞬间到达计算机的信号解算出其始点与测站间的距离。
在自动测量中，Z轴增量累积高差，而其他两个增量被用来在预编程序参考椭球中的经纬度值。计算机同样也指导平台转矩来安置平台，使通过调整过程的北方向与椭球相切。
安置大约每隔4分钟停止一次，进行零速度更新。这将需要三十秒时间使平台重新水平，与当地垂直，有效地复置垂直角零度值。如上所述先前的计算和平台转矩与参考椭球有关，因此利用转矩来重新安置水平线是一种用来测量垂直偏差引起定向改变的方法。车辆静止时，加速计的读数应为零，而且为综合整体速度。所以当卡尔曼滤波详细审查这些数据时，其能够建立由漂移产生的非线性加速计误差，利用这些加速计误差观察漂移改变的几率。由于漂移经过4分钟后精确分析是不可能的，纠正后平台将重新置平。
现在测量过程常连续更换停站点及停在那些发生相同变化过程的测站上。在钟点测站上，已知点的坐标及高度作为更新的信息被输入进去，开始进行零速度的更新。卡尔曼滤波进行均匀调整从而分配闭合差到各测站点。测量数据和改正结果将记录于存储器中。
导线测量通常在同一测站测量两个方向，偏差将表现为在对齐平台上陀螺漂移的影响。当在高程相似的陆地上使用时，如果两点间距达到10km，则标准差可达到±0.2m。
英国Ferranti制造的通信系统，1980年1月17日在New Giril Engineer上报了这一参考值在高速公路建设中的价值。这一报道特别提级他们的惯性道路测量仪，而且表明这一系统适合于陆地测量、建井测量及水下测量。
2 GPS在导航上的应用
2.1 前言
全球定位系统(GPS)这些年在许多领域包括测量、大地测量、地理信息系统（GIS）、气象学、地球动力学已经成为热门话题。这可能是GPS包含许多优点：它解决了许多我们无法解决或我们感到很难解决的问题，也加强了我们比以前更好的处理许多事情的能力。导航系统就是其中之一，GPS的发展使这一系统发生了巨大的变化。
这篇文章将总述GPS在导航中的应用。首先简要介绍GPS的原理，接下来将讨论在导航中不同的GPS定位方法，最后预见基于GPS的海陆空导航系统。
2.2 GPS定位原理
GPS是建立在卫星基础上的一种被动定位系统，最初设计只是在军事上所用。它的持续发展是由美国国防部支持的，这一系统现用于军事和民用，获取一天24小时当中任何时候的天气条件，世界任何地方的高精度位置、速度及时间信息。这一在1993年12月宣布达到了最初的运行能力（IOC），在1995年4月又宣布达到了完全运行能力（FOC）。
2.2.1 GPS的组成
通常将GPS分为三部分：
空间部分，包括GPS卫星，卫星轨道在离地球表面20，000KM之上。GPS的完全运行能力包括24颗活动卫星。目前有27颗可运行卫星，其中3颗备用卫星，用来替换那些当超过服务期的卫星。GPS中的主要部分是用来发送和接受的天线，两个巨大的覆盖太阳能电池板的机翼，用来积累提供卫星运行所需的能量。此外，还有原子钟，其精确度达到1秒/3000，000 年。
控制部分包括5个监测站、3个注入站、1个主控站。监测站被动的跟踪所有可见卫星，收集测距数据。所跟踪收集到数据被发送到主控站，从而确定卫星的轨道同时更新每颗卫星的导航电文。更新的信息通过注入站发送到各个卫星之中。
用户部分是有接受机的任何人，例如：测量人员，导航人员及GIS数据采集人员。
图2 图3
GPS卫星发送的信号由粗码（C/A码）和精码（P码）两种编码及导航电位所组成。编码就像一系列1及0的幅值（如图2）按一定的序列排列组合。C/A码用于标准定位服务（SPS），适用于所有用户，它所提供的定位精度大约为水平方向100m，垂直方向156m，达到95%置信度。P码用于精密定位服务（PPS），且只能被那些授权用户所访问，诸如美国军方及其同盟国，其提供的点位精度大约为水平方向15m，垂直方向25m，达到95%置信度。
GPS导航电文包括诸如以下的信息：卫星轨道参数，时钟参数及每一颗有源卫星年鉴的近似数据。GPS使用L波段上的两个载频承载如上所述的卫星信号。L1载波波长19cm （1575.42MHz），L2载波波长24cm（1227.60MHz）。两种波长均为微波，能够穿透大气层。L1载波承载C/A及P码，而L2载波中仅有P码，两种载波中均承载有导航电文。
对于那些要求比较高的用户，如：测绘人员，利用编码信息来定不能满足他们所需求的厘米或毫米级精度。在这种情况下，利用观测的L1或者L2波段或者使用L1，L2波段也能进行定位。
2.2.2 GPS工作原理
GPS通过测距进行定位测量，GPS卫星的运行轨道已经知道，因此可以求得任一时刻卫星的位置。因此，如果能测出地球表面或其附近上的任一点到3颗或更多颗GPS卫星的距离，那么这一点的三维坐标就能解算出来，如图3。
地面点到卫星的距离可以通过编码测距或者载波相位测量。GPS卫星和接收机在同一时间产生相同的GPS编码，当接收机接收到来自卫星的码信息时，它使自己产生的码相位与接收到的相互关联，如图4。从而可以求得GPS信号从卫星到接收机间的传播时间，利用这一时间便可以解算出距离。
由于接收机时钟的精度低于GPS卫星上的时钟精度，因此在实际解算中通常把时间当作一个未知参数，这一参数将与接收机点位置的未知参数一同被求解。在这种情况下，要求至少接收到4颗GPS卫星信号，因为有4个未知参数需要求解。
当利用载波相位测量进行GPS定位，接收机与卫星间距离解算用到如下公式：Distance=NS+DS
式中：s--表示载波的波长，N--为卫星至接收机整周数，ds--为不足一个波长的相位值，如图5。ds直接可以从相位测量中获得，N为整周模糊度，通常通过延长观测时间以获取连续载波相位观测值来求解。
图4 图5
2.2.3 GPS的利弊争论
这里只给出一些GPS的优点：第一，GPS覆盖全球地面，因此在它的名字中有“全球”两字，而且能够24小时持续观测；第二，该系统以合理的价格提供给用户高精度的点位，在许多应用上GPS使用起来非常方便。
GPS同样有它的缺点：可能最大的问题就是它需要到GPS卫星是一直线视野。GPS能够穿透大气层，但无法穿透任何实物比如建筑物，树木和群山等。这一要求严格的限制了GPS在诸如密集城市地区，地面下等环境的使用。关于GPS的另一个问题是多路径效应，当接收机为平滑反射面时，将产生很明显的误差。
3 GPS在导航中的定位方法
GPS主要设计为一种导航工具，它已经成功的应用于各种交通工具的导航如汽车、轮船、飞机等，同样也用于诸如导弹等武器的导向，这一节主要介绍使用GPS在导航中的不同定位方法。
3.1 单一接收机定位：
使用GPS导航最简单的方式就是无论何时你走到哪都携带GPS接收机，接收机将提供先前提到的实时SPS定位精度，只要能够接收到4颗或更多的GPS卫星信号。这一应用非常基本，几乎市场上出售的任何GPS接收机都能够达到这一目的。许多接收单元还不到﹩100。这种简单的GPS定位方法在娱乐活动上使用非常普遍，比如远足旅行，出海打渔，在沙漠森林等偏僻地区的外业工作，还有海上旅行。
3.2 差分GPS定位
如果上述定位精度无法满足需求，那么一个简单而有效的方法来提高精度就是使用差分GPS定位。在这种操作模式下，需要两台GPS接收机，一台置于已知点上，另一台安置于任何一待测点上。在这种情况下，第一台接收机被称为基准站，第二台被称为移动站。
如果移动站过于接近基准站，那么将产生各种GPS误差比如两测站的大气层效应非常相似。基准站可以被用来确定三维坐标的误差，在这一误差基础上移动站上的位置改正可以解算出来。通过这一差分操作点位精度可以获得很大改进。DGPS（差分GPS定位）多次表明可获得的点位精度达到2—5m，基线长达到1000km。
如果需要实时定位，那么需要连续交换两测站的数据。如果两测站的距离较短只有几公里，则一个常用方法就是使用一对无线电通信设施。当距离达到几百公里时，可以使用广播站发送改正信息到整个设计地区，例如，香港在它的KauYiChau岛上建立了一个永久的GPS 基准站，使用传输器可传播改正信息到直径为500km的地区，这将覆盖整个香港。该系统的精度声称达到1m。
上述差分解算是在有限的覆盖区域内，它严格受到该地区地面通信系统的限制，同时点位精度随着用户与基准站距离的扩大而降低。另一种广域差分GPS定位技术可以克服上述局部差分定位产生的问题。广域差分GPS使用多个GPS基准站，以此覆盖一个广阔的区域诸如一个国家或一个洲。GPS定位误差被单独模拟化并提供给移动站，这种方式打破了位置上的依赖性。因此由于用户与基准站距离过大而产生的导航精度限制可以被大大的排除。定位精度约为2m，水平方向精度达到3m，高程部分也达到相应水平，基线长度从2000km到3500km。数据间连接的限制通过使用地球同步通讯卫星也被克服了。
3.3 附加感应器和信息辅助的GPS
如上所述，由于对GPS卫星的直线视野要求，使得在一些起伏较大而的城市很难使用GPS进行观测。例如，最近测试表明，只有30%的香港用户能够接收到4颗或更多颗GPS 卫星。解决这一问题的一种方法就是辅助GPS即通过使用陀螺和加速计来定位的感应器比如罗盘、高程计、惯性系统（INS），或者附加一些现存地图和数据的信息。
Pseudolite,a pseudo-satellite 正如它的名字是一种能够传播GPS信号的装置。它能够被安置在一些重要的地方如高楼之上，交叉路口来传播信号到附近地区。从pseudolite传来的信号和从真正卫星传来的信号一样能够以相同的方法加以处理。
GPS也可以联合由俄罗斯建立发展的GlLONASS卫星导航系统。GLONASS的设计和工作原理在一定程度上与GPS非常相似。双方的研究人员和指导商已经努力联合这两套系统使之成为一体，从而获得较高的点位精度，特别是在不同的环境下有较好的卫星覆盖率。那种既能接收GPS又能接收GLONASS卫星信号的接收机已经发展起来了。最近由IAG，IERS 和ION组织的国际GLONASS研究试验运动正在展开，这将有望建立一个全球的网络系统，
从而带来国际上的合作研究。
这一系统的完善和GLONASS系统的持续发展总是令人担忧，特别是1997—1998年GLONASS在太空中的卫星数量集聚的减少。
据报道差分GPS+GLONASS的定位精度可小于0.5m.
4 基于GPS的导航系统
基于各种GPS系统上的导航系统已经不断发展，这一节将简要论述这一发展及海陆空导航的基本要求。
4.1 飞机导航
可以理解，在不同的环境下导航有不同的要求。在设计不同导航系统时，无论怎样大体上涉及到系统的精度、可行性、持续性和完善性。
虽然GPS和GLONASS系统的联合提供了很好的定位能力，但是当分开使用时，不能找到一个统一的导航标准，服务于航天导航和陆地指挥，或者用于海上和陆地上紧急情况。为了满足这一要求，已经研制出了GNSS—1和GNSS—2（GNSS同样也属于全球卫星导航系统）GNSS—1是一卫星导航系统，以GPS或GLONASS为支柱，同时由其他技术加以扩充。NASS—1期望满足从单一的导航方法到不确定导航方法的需。NASS—2是第二种卫星导航系统，它能满足所有用户的要求，独立于其他任何方式无线电导航。这一系统的模式还未被确定。
以下是一些有关GNSS—1领域的发展：
欧洲对地静止的导航服务体系
在欧洲，由欧洲航空安全组织（EUROCONTROL），欧洲空间局（ESA），欧洲委员会（EC）组成的集团管理EGNOS，其中EC负责各项制度和政策的发布以及资金的开支，EUROCONTROL确定用户的要求同样也包括系统发展各阶段的测试和有效性，ESA管理EGNOS包括GNSS—1的发展。
EGNOS将覆盖大西洋东部地区及印度洋地区，因为EGNOS利用这些地区的卫星作为体统中心转发器，EGNOS计划在1999年达到最初的可运行能力（IOC）而在2002年完成最终可运行能力（FOC）。
EGNOS将包括GPS及GLONASS的特点，如GPS的测距系统，广阔区域差分系统，连续覆盖的监测站（RIMS）及完善稳定的波段。
区域扩大系统（WAAS）
WAASS是由联合航空公司发展起来的，该地面网络系统包括25个基准站，2个主控站为提高精度差分和ionosphere改正数。为了达到Cat—1所有阶段的不同要求，WAAS将传播发送完整的信息和附加的如GPS信号，包括GPS差分改正数。系统第一阶段最初的辅助性服务计划在2000年9月完成。
WAAS的目标是为Cat—1准确方法提供服务。局部区域扩大系统在原理上与WASS相似，但是其覆盖的区域较少而且有较高的定位精度，它将被应用于Cat—Ⅱ/Ⅲ精确方法中更加严格的要求。
基于MTSAT卫星的扩充系统（MSAS）
基于日本多功能传输卫星的扩充系统是由日本民航局（JCAB）发展起来的，它支持整个飞行阶段路线中采用单一手段的导航服务。第一个MTSAT计划在1999年启动，该系统的第一阶段将在2001年前完成并且MSAS的最终运行能力计划在2005实现。
MSAS在设计中提供了空中交通服务及处理气象任务。这一系统的构造与美国的WASS 系统相似，包括传播完整准确数据的地面网络，用来提供从对地静止卫星传来的类似GPS信号，从而改进系统的可行性和持续性。
GNSS—2的发展必须考虑到公共制度上的有关系统所有权，控制权与互用性的问题。在ICAO（国际民航组织）成员的一致认可下，建立了相互合作工作，并且在1998年7月召开了第一次会议来讨论这些问题。合作组表明已经对WAAS/EFNOA和WAAS/MSAS安排好计划。
4.2 陆地导航系统
陆地交通导航系统主要提供一些有关信息诸如，汽车的时实位置，从一个地方到另一个地方的最短路径或者最少时间的线路。一个完整的导航系统同样也需增加在地图上显示车辆的时实动态位置的功能。除此之外，在控制中心有必要跟踪所有车辆的位置，诸如出租车，公交车等。在各车辆和控制中心之间同样需要无线电数据的传输联系。
智能交通系统（ITS）引起许多研究人员包括政府运输部门的广泛兴趣，除以上所述的陆地交通系统的基本功能外，ITS也有其自身特点，诸如：自动付费、智能控制交通信号。
基于卫星通讯的陆地交通导航系统一个最主要的问题就是卫星信号被诸如建筑物、桥梁、行人及周围的车辆所遮挡。特别是在一些密度大和起伏较大的城市如香港。因此，通常有必要增加一个基于卫星基础之上的位置系统。该系统包括一些如罗盘、里程计、INS传感器。在不同地区获得不同定位精度的要求，同时又要保证导航系统的成本较低，这仍然是一个研究的领域。
4.3 海上导航
最先的海上导航系统要求是为船只在宽阔海域航行时提供位置和方向信息。它同样需要提供准确的路径和避免冲突的路线。海上导航可以使用单台接收机，DGPS或者精度更高的系统GNSS，这主要取决于导航的需要。
5 综述
在这篇文章中，给出了有关GPS方面的介绍；基于GPS的各种定位方法，包括使用单一接收机，差分GPS，增加传感器和信息的辅助GPS；介绍了基于GPS发展的导航系统，简要地回顾了一些现存的海陆空导航系统。
对于许多定位应用的领域如测量和导航，GPS是一个新兴的强大的工具，它在时间和空间上提供了一个史无前例的保证。该系统给用户以相对较低的成本提供了一个高的定位精度。GPS的主要不利条件包括对GPS卫星直线视野的要求和多路径误差。
很清楚的看到，为了提供安全，更有效而且低成本的导航服务，基于卫星的导航系统将成为一个综合的系统，其将包括不同的传感器与技术，提供全球覆盖和完善的互操作性。
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华北电力大学科技学院 毕业设计（论文）附件 外文文献翻译 学号：121912020115姓名：彭钰钊 所在系别：动力工程系专业班级：测控技术与仪器12K1指导教师：李冰 原文标题：Infrared Remote Control System Abstract 2016 年 4 月 19 日
红外遥控系统 摘要 红外数据通信技术是目前在世界范围内被广泛使用的一种无线连接技术，被众多的硬件和软件平台所支持。红外收发器产品具有成本低，小型化，传输速率快，点对点安全传输，不受电磁干扰等特点，可以实现信息在不同产品之间快速、方便、安全地交换与传送，在短距离无线传输方面拥有十分明显的优势。红外遥控收发系统的设计在具有很高的实用价值，目前红外收发器产品在可携式产品中的应用潜力很大。全世界约有1亿5千万台设备采用红外技术，在电子产品和工业设备、医疗设备等领域广泛使用。绝大多数笔记本电脑和手机都配置红外收发器接口。随着红外数据传输技术更加成熟、成本下降，红外收发器在短距离通讯领域必将得到更广泛的应用。 本系统的设计目的是用红外线作为传输媒质来传输用户的操作信息并由接收电路解调出原始信号，主要用到编码芯片和解码芯片对信号进行调制与解调，其中编码芯片用的是台湾生产的PT2262，解码芯片是PT2272。主要工作原理是：利用编码键盘可以为PT2262提供的输入信息，PT2262对输入的信息进行编码并加载到38KHZ的载波上并调制红外发射二极管并辐射到空间，然后再由接收系统接收到发射的信号并解调出原始信息，由PT2272对原信号进行解码以驱动相应的电路完成用户的操作要求。 关键字：红外线；编码；解码；LM386；红外收发器。 1 绪论
毕业设计（论文）外文文献翻译 文献、资料中文题目：软件开发概念和设计方法文献、资料英文题目： 文献、资料来源： 文献、资料发表（出版）日期： 院（部）： 专业： 班级： 姓名： 学号： 指导教师： 翻译日期： 2017.02.14
外文资料原文 Software Development Concepts and Design Methodologies During the 1960s, ma inframes and higher level programming languages were applied to man y problems including human resource s yste ms,reservation s yste ms, and manufacturing s yste ms. Computers and software were seen as the cure all for man y bu siness issues were some times applied blindly. S yste ms sometimes failed to solve the problem for which the y were designed for man y reasons including: ?Inability to sufficiently understand complex problems ?Not sufficiently taking into account end-u ser needs, the organizational environ ment, and performance tradeoffs ?Inability to accurately estimate development time and operational costs ?Lack of framework for consistent and regular customer communications At this time, the concept of structured programming, top-down design, stepwise refinement，and modularity e merged. Structured programming is still the most dominant approach to software engineering and is still evo lving. These failures led to the concept of "software engineering" based upon the idea that an engineering-like discipl ine could be applied to software design and develop ment. Software design is a process where the software designer applies techniques and principles to produce a conceptual model that de scribes and defines a solution to a problem. In the beginning, this des ign process has not been well structured and the model does not alwa ys accurately represent the problem of software development. However,design methodologies have been evolving to accommo date changes in technolog y coupled with our increased understanding of development processes. Whereas early desig n methods addressed specific aspects of the
摘要： 建筑工程在施工过程中，施工组织方案的优劣不仅直接影响工程的质量，对工期及施工过程中的人员安全也有重要影响。施工组织是项目建设和指导工程施工的重要技术经济文件。能调节施工中人员、机器、原料、环境、工艺、设备、土建、安装、管理、生产等矛盾,要对施工组织设计进行监督和控制,才能科学合理的保证工程项目高质量、低成本、少耗能的完成。 关键词： 项目管理施工组织方案重要性 施工组织设计就是对工程建设项目整个施工过程的构思设想和具体安排，是施工组织管理工作的核心和灵魂。其目的是使工程速度快、质量好、效益高。使整个工程在施工中获得相对的最优效果。 1．编制施工组织设计重要性的原因 建筑工程及其施工具有固定性与流动性、多样性与单件性、形体庞大与施工周期长这三对特点。所以，每一建筑工程的施工都必须进行施工组织设计。这是因为：其它一般工业产品的生产都有着自己固定的、长期适用的工厂。而建筑施工具有流动性的特点，不可能建立这样的工厂，只能是当每一个建筑工程施工时，建立一个相应的、临时性的，如同工厂作用性质的施工现场准备，即工地。施工单件性特点与施工流动性特点，决定了每一建筑工程施工都要选择相应的机具和劳动力组织。选择施工方法、拟定施工技术方案及其劳动力组织和机具配置，统称为施工作业能力配置。施工周期的特点，决定了各种劳动力、机具和众多材料物资技术的供应时间也比较长，这就产生了与施工总进度计划相适应的物资技术的施工组织设计内容。由此可见，施工组织设计在项目管理中是相当重要的。 2．施工组织设计方案的重要性 建筑产品作为一种商品，在项目管理中工程质量在整个施工过程中起着极其重要的作用。工程建设项目的施工组织设计与其工程造价有着密切的关系。施工组织设计基本的内容有：工程概况和施工条件的分析、施工方案、施工工艺、施工进度计划、施工总平面图。还有经济分析和施工准备工作计划。其中,施工方案及施工工艺的确定更为重要,如:施工机械的选择、水平运输方法的选择、土方的施工方法及主体结构的施工方法和施工工艺的选择等等,均直接影响着工程预算价格的变化。在保证工程质量和满足业主使用要求及工期要求的前提下,优化施工方案及施工工艺是控制投资和降低工程项目造价的重要措施和手段。 2.1施工组织方案在很大程度上影响着工程质量，因此合理的施工组织方案不仅是确保工程顺利完成的基础，也是工程安全的依据。施工组织设计是建筑工
A convection-conduction model for analysis of the freeze-thaw conditions in the surrounding rock wall of a tunnel in permafrost regions Abstract Based on the analyses of fundamental meteorological and hydrogeological conditions at the site of a tunnel in the cold regions, a combined convection-conduction model for air flow in the tunnel and temperature field in the surrounding has been constructed. Using the model, the air temperature distribution in the Xiluoqi No. 2 Tunnel has been simulated numerically. The simulated results are in agreement with the data observed. Then, based on the in situ conditions of sir temperature, atmospheric pressure, wind force, hydrogeology and engineering geology, the air-temperature relationship between the temperature on the surface of the tunnel wall and the air temperature at the entry and exit of the tunnel has been obtained, and the freeze-thaw conditions at the Dabanshan Tunnel which is now under construction is predicted. Keywords: tunnel in cold regions, convective heat exchange and conduction, freeze-thaw. A number of highway and railway tunnels have been constructed in the permafrost regions and their neighboring areas in China. Since the hydrological and thermal conditions changed after a tunnel was excavated，the surrounding wall rock materials often froze, the frost heaving caused damage to the liner layers and seeping water froze into ice diamonds，which seriously interfered with the communication and transportation. Similar problems of the freezing damage in the tunnels also appeared in other countries like Russia, Norway and Japan .Hence it is urgent to predict the freeze-thaw conditions in the surrounding rock materials and provide a basis for the design，construction and
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。
XXXXXXXXX 毕业设计（论文）外文翻译 学生姓名： 院（系）： 专业班级： 指导教师： 完成日期：
施工组织设计的重要性 摘要： 建筑工程在施工过程中，施工组织方案的优劣不仅直接影响工程的质量，对工期及施工过程中的人员安全也有重要影响。施工组织是项目建设和指导工程施工的重要技术经济文件。能调节施工中人员、机器、原料、环境、工艺、设备、土建、安装、管理、生产等矛盾,要对施工组织设计进行监督和控制,才能科学合理的保证工程项目高质量、低成本、少耗能的完成。 关键词： 项目管理施工组织方案重要性 施工组织设计就是对工程建设项目整个施工过程的构思设想和具体安排，是施工组织管理工作的核心和灵魂。其目的是使工程速度快、质量好、效益高。使整个工程在施工中获得相对的最优效果。 1.编制施工组织设计重要性的原因 建筑工程及其施工具有固定性与流动性、多样性与单件性、形体庞大与施工周期长这三对特点。所以，每一建筑工程的施工都必须进行施工组织设计。这是因为：其它一般工业产品的生产都有着自己固定的、长期适用的工厂。而建筑施工具有流动性的特点，不可能建立这样的工厂，只能是当每一个建筑工程施工时，建立一个相应的、临时性的，如同工厂作用性质的施工现场准备，即工地。施工单件性特点与施工流动性特点，决定了每一建筑工程施工都要选择相应的机具和劳动力组织。选择施工方法、拟定施工技术方案及其劳动力组织和机具配置，统称为施工作业能力配置。施工周期的特点，决定了各种劳动力、机具和众多材料物资技术的供应时间也比较长，这就产生了与施工总进度计划相适应的物资技术的施工组织设计内容。由此可见，施工组织设计在项目管理中是相当重要的。 2.施工组织设计方案的重要性 建筑产品作为一种商品，在项目管理中工程质量在整个施工过程中起着极其重要的作用。工程建设项目的施工组织设计与其工程造价有着密切的关系。施工组织设计基本的内容有：工程概况和施工条件的分析、施工方案、施工工艺、施工进度计划、施工总平面图。还有经济分析和施工准备工作计划。其中,施工方案及施工工艺的确定更为重要,如:施工机械的选择、水平运输方法的选择、土方的施工方法及主体结构的施工方法和施工工艺的选择等等,均直接影响着工程预算价格的变化。在保证工程质量和满足业主使用要求及工期要求的前提下,优化施工方案及施工工艺是控制投资和降低工程项目造价的重要措施和手段。 2.1施工组织方案在很大程度上影响着工程质量，因此合理的施工组织方案 不仅是确保工程顺利完成的基础，也是工程安全的依据。施工组织设计是建筑工程设计文件的重要组成部分，是编制工程投资概预算的主要依据和编制招投标文件的
I / 11 本科毕业设计外文翻译 <2018届） 论文题目基于WEB 的J2EE 的信息系统的方法研究 作者姓名[单击此处输入姓名] 指导教师[单击此处输入姓名] 学科(专业 > 所在学院计算机科学与技术学院 提交日期[时间 ]
基于WEB的J2EE的信息系统的方法研究 摘要：本文介绍基于工程的Java开发框架背后的概念，并介绍它如何用于IT 工程开发。因为有许多相同设计和开发工作在不同的方式下重复，而且并不总是符合最佳实践，所以许多开发框架建立了。我们已经定义了共同关注的问题和应用模式，代表有效解决办法的工具。开发框架提供：<1）从用户界面到数据集成的应用程序开发堆栈；<2）一个架构，基本环境及他们的相关技术，这些技术用来使用其他一些框架。架构定义了一个开发方法，其目的是协助客户开发工程。 关键词：J2EE 框架WEB开发 一、引言 软件工具包用来进行复杂的空间动态系统的非线性分析越来越多地使用基于Web的网络平台，以实现他们的用户界面，科学分析，分布仿真结果和科学家之间的信息交流。对于许多应用系统基于Web访问的非线性分析模拟软件成为一个重要组成部分。网络硬件和软件方面的密集技术变革[1]提供了比过去更多的自由选择机会[2]。因此，WEB平台的合理选择和发展对整个地区的非线性分析及其众多的应用程序具有越来越重要的意义。现阶段的WEB发展的特点是出现了大量的开源框架。框架将Web开发提到一个更高的水平，使基本功能的重复使用成为可能和从而提高了开发的生产力。 在某些情况下，开源框架没有提供常见问题的一个解决方案。出于这个原因，开发在开源框架的基础上建立自己的工程发展框架。本文旨在描述是一个基于Java的框架，该框架利用了开源框架并有助于开发基于Web的应用。通过分析现有的开源框架，本文提出了新的架构，基本环境及他们用来提高和利用其他一些框架的相关技术。架构定义了自己开发方法，其目的是协助客户开发和事例工程。 应用程序设计应该关注在工程中的重复利用。即使有独特的功能要求，也
文献出处：Thronson P. Toward Comprehensive Reform of America’s Emergency Law Regime [J]. University of Michigan Journal of Law Reform, 2013, 46(2). 原文 TOWARD COMPREHENSIVE REFORM OF AMERICA’S EMERGENCY LAW REGIME Patrick A. Thronson Unbenownst to most Americans, the United States is presently under thirty presidentially declared states of emergency. They confer vast powers on the Executive Branch, including the ability to financially incapacitate any person or organization in the United States, seize control of the nation’s communications infrastructure, mobilize military forces, expand the permissible size of the military without congressional authorization, and extend tours of duty without consent from service personnel. Declared states of emergency may also activate Presidential Emergency Action Documents and other continuity-of-government procedures, which confer powers on the President—such as the unilateral suspension of habeas corpus—that appear fundamentally opposed to the American constitutional order.
Optimum blank design of an automobile sub-frame Jong-Yop Kim a ,Naksoo Kim a,*,Man-Sung Huh b a Department of Mechanical Engineering,Sogang University,Shinsu-dong 1,Mapo-ku,Seoul 121-742,South Korea b Hwa-shin Corporation,Young-chun,Kyung-buk,770-140,South Korea Received 17July 1998 Abstract A roll-back method is proposed to predict the optimum initial blank shape in the sheet metal forming process.The method takes the difference between the ?nal deformed shape and the target contour shape into account.Based on the method,a computer program composed of a blank design module,an FE-analysis program and a mesh generation module is developed.The roll-back method is applied to the drawing of a square cup with the ˉange of uniform size around its periphery,to con?rm its validity.Good agreement is recognized between the numerical results and the published results for initial blank shape and thickness strain distribution.The optimum blank shapes for two parts of an automobile sub-frame are designed.Both the thickness distribution and the level of punch load are improved with the designed blank.Also,the method is applied to design the weld line in a tailor-welded blank.It is concluded that the roll-back method is an effective and convenient method for an optimum blank shape design.#2000Elsevier Science S.A.All rights reserved. Keywords:Blank design;Sheet metal forming;Finite element method;Roll-back method
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/ac17776206.html,，niuzhiguo@https://www.doczj.com/doc/ac17776206.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/ac17776206.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。
文献出处: Phillip Yetton. The Study of Construction Organization Design [J]. International Journal of Project Management, 2015, 9(2): 33-43. 原文 The Study of Construction Organization Design Author: Phillip Yetton Abstract Building construction is a complex work, huge building products, the production cycle is long, is a collection of architectural art, architecture, function, structure, decoration, water supply, power supply, intelligent system for a wind. Need to complete a project unit, type of work well together, and in the process of implementing, also under the influence of various subjective and objective conditions around. In order to meet the quality, cost, time limit for a project, under the premise of safety goal task to complete a project, must according to the requirement of the construction unit and the characteristics of the proposed construction project, the various raw materials on the basis of full investigation, compile an used to guide the whole process of technology, economy and management of project construction comprehensive document, this document is the construction organization Keywords: Construction; Organization design; Project cost 1 Introduction Construction organization design is a construction project for the object establishment, to guide the project bidding, construction contracts, construction preparation, construction installation until the whole process of the final acceptance of the technology, economy and management comprehensive document, is to ensure that project smooth implementation effective programmatic document. Construction organization design is proper or not, will directly relate to the quality of the proposed construction project, cost, time limit, safety, etc. The smooth realization of the intended target. With the development of The Times, modern engineering project scale and the demand is higher and higher, project management has become increasingly complex, and the construction organization design also put forward higher requirements. The construction organization design, construction organization
Section 3 Design philosophy, design method and earth pressures 3.1 Design philosophy 3.1.1 General The design of earth retaining structures requires consideration of the interaction between the ground and the structure. It requires the performance of two sets of calculations: 1）a set of equilibrium calculations to determine the overall proportions and the geometry of the structure necessary to achieve equilibrium under the relevant earth pressures and forces; 2）structural design calculations to determine the size and properties of thestructural sections necessary to resist the bending moments and shear forces determined from the equilibrium calculations. Both sets of calculations are carried out for specific design situations (see 3.2.2) in accordance with the principles of limit state design. The selected design situations should be sufficiently Severe and varied so as to encompass all reasonable conditions which can be foreseen during the period of construction and the life of the retaining wall. 3.1.2 Limit state design This code of practice adopts the philosophy of limit state design. This philosophy does not impose upon the designer any special requirements as to the manner in which the safety and stability of the retaining wall may be achieved, whether by overall factors of safety, or partial factors of safety, or by other measures. Limit states (see 1.3.13) are classified into: a) ultimate limit states (see 3.1.3); b) serviceability limit states (see 3.1.4). Typical ultimate limit states are depicted in figure 3. Rupture states which are reached before collapse occurs are, for simplicity, also classified and
附件1：外文资料翻译译文 包装对食品发展的影响 一个消费者对某个产品的第一印象来说包装是至关重要的，包括沟通的可取性，可接受性，健康饮食形象等。食品能够提供广泛的产品和包装组合，传达自己加工的形象感知给消费者，例如新鲜包装/准备，冷藏，冷冻，超高温无菌，消毒（灭菌），烘干产品。 食物的最重要的质量属性之一，是它的味道，其影响人类的感官知觉，即味觉和嗅觉。味道可以很大程度作退化的处理和/或扩展存储。其他质量属性，也可能受到影响，包括颜色，质地和营养成分。食品质量不仅取决于原材料，添加剂，加工和包装的方法，而且其预期的货架寿命（保质期）过程中遇到的分布和储存条件的质量。越来越多的竞争当中，食品生产商，零售商和供应商；和质量审核供应商有显着提高食品质量以及急剧增加包装食品的选择。这些改进也得益于严格的冷藏链中的温度控制和越来越挑剔的消费者。 保质期的一个定义是：在食品加工和包装组合下，在食品的容器和条件，在销售点分布在特定系统的时间能保持令人满意的食味品质。保质期，可以用来作为一个新鲜的概念，促进营销的工具。延期或保质期长的产品，还提供产品的使用时间，方便以及减少浪费食物的风险，消费者和/或零售商。包装产品的质量和保质期的主题是在第3章中详细讨论。 包装为消费者提供有关产品的重要信息，在许多情况下，使用的包装和/或产品，包括事实信息如重量，体积，配料，制造商的细节，营养价值，烹饪和开放的指示，除了法律准则的最小尺寸的文字和数字，有定义的各类产品。消费者寻求更详细的产品信息，同时，许多标签已经成为多语种。标签的可读性是为视障人士的问题，这很可能成为一个对越来越多的老年人口越来越重要的问题。 食物的选择和包装创新的一个主要驱动力是为了方便消费者的需求。这里有许多方便的现代包装所提供的属性，这些措施包括易于接入和开放，处置和处理，产品的知名度，再密封性能，微波加热性，延长保质期等。在英国和其他发达经济体显示出生率下降和快速增长的一个相对富裕的老人人口趋势，伴随着更加苛
毕业设计（论文） 外文文献翻译 题目：A new constructing auxiliary function method for global optimization 学院： 专业名称： 学号： 学生姓名： 指导教师： 2014年2月14日
一个新的辅助函数的构造方法的全局优化 Jiang-She Zhang，Yong-Jun Wang https://www.doczj.com/doc/ac17776206.html,/10.1016/j.mcm.2007.08.007 非线性函数优化问题中具有许多局部极小，在他们的搜索空间中的应用，如工程设计，分子生物学是广泛的，和神经网络训练．虽然现有的传统的方法，如最速下降方法，牛顿法，拟牛顿方法，信赖域方法，共轭梯度法，收敛迅速，可以找到解决方案，为高精度的连续可微函数，这在很大程度上依赖于初始点和最终的全局解的质量很难保证．在全局优化中存在的困难阻碍了许多学科的进一步发展．因此，全局优化通常成为一个具有挑战性的计算任务的研究． 一般来说，设计一个全局优化算法是由两个原因造成的困难：一是如何确定所得到的最小是全球性的（当时全球最小的是事先不知道），和其他的是，如何从中获得一个更好的最小跳．对第一个问题，一个停止规则称为贝叶斯终止条件已被报道．许多最近提出的算法的目标是在处理第二个问题．一般来说，这些方法可以被类?主要分两大类，即：（一）确定的方法，及（ii）的随机方法．随机的方法是基于生物或统计物理学，它跳到当地的最低使用基于概率的方法．这些方法包括遗传算法（GA），模拟退火法（SA）和粒子群优化算法（PSO）．虽然这些方法有其用途，它们往往收敛速度慢和寻找更高精度的解决方案是耗费时间．他们更容易实现和解决组合优化问题．然而，确定性方法如填充函数法，盾构法，等，收敛迅速，具有较高的精度，通常可以找到一个解决方案．这些方法往往依赖于修改目标函数的函数“少”或“低”局部极小，比原来的目标函数，并设计算法来减少该?ED功能逃离局部极小更好的发现． 引用确定性算法中，扩散方程法，有效能量的方法，和积分变换方法近似的原始目标函数的粗结构由一组平滑函数的极小的“少”．这些方法通过修改目标函数的原始目标函数的积分．这样的集成是实现太贵，和辅助功能的最终解决必须追溯到