测绘工程 外文翻译--水准尺和水准仪

测绘工程 外文翻译--水准尺和水准仪 外文资料 Level Rods and Lenels There are many kinds of lenel rods available.Some are in one piece and others (for ease of transporting) are either telescoping or hinged.Level rods are usually made of wood and are graduated from zero at the bottom.They may be either selfreading rods that are read directly through the telescope or targetrods where the rodman sets a sliding target on the rod and takes the reading directly. Most rods serve as either self-reading or as target rods. Among the several types of level rods available are the Philadelphia rod,the Chicago rod, and the Florida rod. The Philadelphia rod, the most common one, is made in two sections. It has a rear section that slides on the front section. For readings between 0 and 7 ft, the rear section is not extended; for reading between 7 and 13 ft, it is necessary to extended the rod. When the rod is extended,it is called a high rod. The Philadelphia rod is distinctly divided into feet, tenths, and hundredths by means of alternating black and white spaces painted on the rod. The Chicago rod is 12 ft long and is graduated in the same way as the Philadelphia rod, but it consists of three sliding section. The Florida rod is 10 ft long and is graduated in white an red stripes, each stripe being 0.10 ft wide. Also available for ease of transportation are tapes or ribbons of waterproofed fabric which are marked in the same way that a regular level rod is marked and which can be attached to ordinary wood strips. Once a job is completed, the ribbon can, be removed and rolled up. The wood strip can be thrown away. The instrumentman can clearly read these various level rods through his telescope for distances up to 200 or 300 ft, but for greater distances he must use a target. A target is a small red and white piece of metal attached to the rod. The target has a vemier that enables the rodman to take a reading to the nearest 0.001 ft. If the rodman is taking the readings with a target and if the line of sight of the telescope is above the 7-ft mark, it is obvious that he cannot take the reading directly in the normal fashion. Therefore, the back face of the rod is numbered downward 文献 from 7 to 13 ft. The target is set at acertain mark on the front face of the rod and as the back section is pushed upward, it runs under an index scale and a vernier which enables the rodman to take the reading on the front. Before setting up the level the instrumentman should give some though to where he must stand in orde to make his sights. In other words, he will consider how to place the tripod legs so that he can stand comfortably between them for the lay-out of the work that he has in mind. The tripod is desirably placed in solid ground where the instrument will not settle as it mose certainly will in muddy or swampy areas. It may be necessary to provide some special support for the instrument, such as stakes or a platform. The tripod legs should be well spread apart and adjustde so that the footplate under the leveling screws is approximately level. The insatrumentman walks around the instrument and pushes each leg frimly into the ground. On hillsides it is usually convenient to place ong leg uphill and two downhill. After the instrument has been levelde as much as possible by adjusting the tripod legs, the telescope is turned over a pair of opposite leveling screws if a four-screw instrument is being used.Then the bubble is roughly centered by turning that pair of screw in opposite directions to each other. The bubble will move in the direction of the left thumb. Next, the telescope is turned over the other pair of leveling screws and the bubble is again roughly centered. The telescope is turned back iver the first pair and the bubble is again roughly centered, and so on. This process is repeated a few more times with increasing care untill the bubble is centered with the telescope turned over either pair of screws. If the level is properly sdjusted, the bubble should remain centered when the telescopeis turued in any direction. It is to be expected that there will be a slight maladjustment of the instrument that will result in a slight movement of the bubble; however, the precision of thework should not be adversely affected if the bubble is centered each time a rod reading is taken. The first step in leveling a three-screw instrument is to turn the telescope untill the bubble tube is parallel to two of the screws. The bubble is centered by turning these two screws in opposite directions. 文献 Next, the telescope is turned so that the bubble tube is perpendicular to a line through screws. The bubble is centered by turning screw . These steps are repeated untill the bubble stays centered when the telescope is turned back and forth. Electronic Distance Measurements A major advance in surveying in recent years has been the development of electronic distance-measuring instruments (ED-MIs). These devices determine lengths based on phase changes that occur as eletromagnetic energy of known wavelength travels from one end of a line to the other and returns. The first EDM instrument was intronduced in 1948 by Swedish physicist Erik Bergstrand. His device, called the geodimeter(an acronym for geodetic distance meter), resulted from attempts to improve methods for measuring the velocity of light. The instrument transmetted visible light and was capable of accurately measuring distances up to about 25 mi (40km) at night. In 1957 a second EDM apparatus. the tellurometer. Designed by Dr.D.L.Wadley and introduced in South Africa, transmitted invisible microwaves and was capable of measuring distances up to 50 mi (80km) or more.day or night. The potential value of these early EDM models to the Surveying profession was immediately recognized: houever, they were expensive and not readily portable for field operations. Furthermore, measuring procedures were lengthy and mathematical reductions to obtain distances from observed values were difficult and time-consuming. In addition. The range of operation of the first geodimeter was limited in daytime use. Continued research and development have overcome all these deficiencies. The chief advantages of electronic surveying are the speed and accuracy with which distances can be measured. If a line of sight is available, long or short lengths can be measured over bodies of water or terrain that is inaccessible for taping. With modern EDM equipment, distance are automatically displayed in digital form in feet or meters, and many have built-in microcomputers that give results internally reduced to horizontal and vertical components. Their many significant advantages have 文献 revolutionized surveying procedures and gained worldwide acceptance. The long-distance measurements possible with EDM equipment make use of radios for communication, which is an absolute necessity in modern practice. One syetem for classifying EDMIs is by wavelength of transmitted electromagnetic energy ; the following categories exist : Electro-optical instruments Which transmit either modulatedlaser or infrared light having wavelengths within or slightly beyond the visible region of the spectrum. Microwave equipments Which transmits microwaves with frequencies in the range of 3 to 35 GHz corresponding to wavelengths of about 1.0 to 8.6 mm. Another classification system for EDMIs is by operational range . It is rather subjective , but in general two divisions fit into this system : short and medium range .The short-range group includes those devices whose macimum measuring capability does not exceed about 5km . Most equipment in this division is the electro –optical type and uses infrared light . These instruments are small, portable, easy to operate, suitable for a wide variety of field surveying work, and used by many practitioners. Instruments in the medium-range group have measuring capabilities extending to about 100 km and are either the electro-optical (using laser light) or microwave type. Although frequently used in precise geodetic they are also suitable for land and engineering surveys. Longer-range device also available can measure lines longer than 100km,but they are nit generally used in ordinary surveying work. Most operate by trasmitting long radio waves, but some employ microwaves. They are used primarily in oceanogaraphic and hydrograpgic surving and navigation. In general, EDM equiment measures distances by comparing aline of unkown length to the known wavelength of modulated electromagnetic energy. This is similar to relating a needed distance to the calibrated length of a steel tape. Electromagnetic energy propagates through the atmosphere in accordances with the following equation: V=fλ (1) Where Vis the velocity of electromanetic energy, in meters per second;f the modulated 文献 frequency of the energy ,in hertz, and λthe wavelenth, in meteres. With EDMIs frequency can be precisely controlled but velocity varies with atmophere temperature, pressure,and humidity. Thus wavelength and frequency must vary in conformance with EQ.(1). For accurate electronic distance measuement, therefor., the atmosphere must be sampled and corrctios made accordingly. The generalizedprocedure of measuring distance electronically is depicted in Fig.8-1. an edm device, centered by means of a plumb bob or optical plummit over staton A, trasmits a carrier signal of electromagnetic energy upon which a reference frequency has been superimposed or modulated. The signal is returned from staion B to the revevier, so its trvel path is double the slope distance AB. In Fig.8-1,the modulated electromagnetic energy is represented by a series of sine waves having wave-length λ. Any position along a givenj wave can be specified by its phase angle, which is 0?at its beginning, 180?at the midpoint, and 360?at its end. EDM devices used in surveying operate by measuring phase shift. In this procedure, the returned energy undergoes a complete 360?phase change for each even multiple of exactly one-half the wavelength separating the line-s endpoints. If, therefore, the distance is precisely equal to a full multiple of the half-wave-length, the indicated phase change will be zero. In Fig.8-1.for example, stations A and B are exactly eight half-wavelengths apart : hence, the phase change is zero. When a line is not exactly an even meltiple of the halfwavelength (the usual case) , the fractional part is measured by the instrument as a nonzero phase angle or phase change. If the precise length of a wave is known, the fractional part can be converted to distance. EDMIs directly resolve the fractional wavelength bu do not count the full cycles undergone by the returned energy in traveling its double path. This ambiguity is resolved, however, by transmetting additional signals of lower frequency and longer wavelengths. 中文翻译 水准尺和水准仪 有许多类型的有价值的水准尺，一些是一体的，另一些(为了运输的安全) 要么是需安装望远镜，要么是得安装绞链，水准尺通常是由木材制成的，并且在 文献 底端刻度从零开始，他们可以通过望远镜或者通过司尺员在尺上设置的觇标来直接读数。大多数水准尺既可以自读又可以作为觇标水准尺。 在使用的几种水准尺中有费拉德尔菲亚水准尺，芝加哥水准尺和佛罗里达水准尺，费拉德尔菲亚水准尺由两部分组成，是最普通的一种。它有一个后续部分，其前面部分上可以滑动。读数在7-13英尺之间时，后面部分不必延伸出来;读数在7-13英尺之间，则要延伸水准尺。当水准尺被延伸时，则被称为高标尺。菲亚水准尺被分为英尺、十分之英尺、百分之读尺(被尺子上黑白相间的交换的条节划分开)。 芝加哥水准尺是12英尺，其刻度划分与菲亚尺相同，但它由三个滑动的部分组成。佛罗里达有10英尺长，刻度由红、白条带划分，每一条带有0.1英尺宽。另外为了运输方便也采用防水织物作的带尺，这种带尺的分划与普通水准尺的分划 方法 快递客服问题件处理详细方法山木方法pdf计算方法pdf华与华方法下载八字理论方法下载 是相同的，而且可以贴在普通木条上。一但工作完成，带尺便可以重新移动或若卷起，而木条则可以扔掉。测量员可以在200-300英尺之外通过望远镜用战标清晰地读出各种水准尺的读数。战标是附加在标尺上很小的、红白相间的金属卡。战标上的游标可以让司尺员读到近0.001英尺。 如果司尺员使用战标读数，且望远镜超过7英尺，显然，司尺员这时无法进行正常的读数。因此，水准尺背面是从低端开始7-13英尺。战标被安置在水准尺前面，并且后面部分被拉起来以后，战标移动一个刻度，以便让司尺员在水准尺前面读数。 在安置水准仪前，观测员应该想到他应该站在什么地方观测。换句话说，他应该考虑到如何安置三角架的腿，以便他能舒服的站在腿的中间，测他所想的工作。 三脚架应安置在坚硬的、仪器不下沉的地面上，当然大多数都安置在松软时而下沉的地方。给仪器提供一些特殊的支持如林庄或平台是必要的。三角架的腿应该合适地展开并调节以便使水平脚，螺旋下的底座能够接近水平。观册员绕着仪器将三脚架每条腿伸长固定在地面上。在山上时，通常将一条腿安上山坡上，两条腿安在山坡下，更便于观测。 通往调节三条腿尺可能使仪器整平。如果使用的是四个脚螺旋，望远镜要转到一对向相反方向转动的脚螺旋上。通过向相反方向转动两个脚螺旋，水准气泡文献 粗略对中，气泡将向左手大拇指方向移动。接着，望远镜转向另一对相对的脚螺旋，水准气泡又一次粗略的对中。这个过程要小心的重复几次，直到望远镜转到任意一对脚螺旋的方向气泡都对中。如果水准仪整平了，那么望远镜转到任一方向时，气泡应保持对中。我们期望仪器轻微移动时，气泡也轻微的移动。无论如何，如果每次读数时气泡都居中，观测的精度不应该有不利的影响。 在整平三角架脚螺旋时，第一步转动望远镜，向相反方向调节两个脚螺旋。 接下来转动望远镜，以使水准管垂直于脚螺旋1和2，调节使其居中，重复这些步骤，直到望远镜来回转动时气泡保持居中。 电子测距仪 近年来，测量中的主要进步是电子测距仪的发展，当已知波长的电波能从一条边的一端传播一另一端并返回时就发生了相变，这些装置就是根据这些来测定长度的。 最早介绍电子测距仪的确1984年瑞典的物理学家Erik Bergstrand,他的装置，命名为光电测距仪(gecdetic distance meter的首字母缩写)，结果导致从实验到改进测量光速的方法。在晚上，仪器传送可见，并且可精确40km的距离。1957年，第二代EDM仪器产生，微波测距仪由D.K博士发明并介绍到南非，传送不可见的微波可全天观测，距离在80km以上。 这些早期的EDM模型对测量专业的潜在价值立即被人们认可，尽管他们是昂贵的，甚至在里子外操作是不轻便的，并且测量的过程是冗长的，而且从数据中获取有用价值是困难的。另外，在宽广区域，第一代测距仪在白天的使用有限，持续的研究和发展攻破了所以的疑难问题。 电子测量最大的优势是提高了测量的速度和精度，如果视线是有限的，那么长波或是短波都可以通过水体或是不可能到达的地势而测的，现代EDM距离在仪器上可以以英尺或者米自动显示，并且许多给出的水平和垂直上的数字都已建立在微机上，他们许多重要的合优势已经改变了测量的进程并且得到世界蝗认可，在实践中，使用EDM距离测量使无线电信号变得非常有必要。 EDMIS的分类系统是从传递电子磁能的波长来分类的，可分为: 光学电子仪器，它传递调制的红外线，红外线光在可见光范围内或稍微越出范围外存在。 文献 微波仪器，它传送微波的频率为3000-35000HZ，相当于1.0到2.1mm的波长。 另一种分类按使用范围分的。它是相当主观的，但通常两种方法都适用这种系统:短波和长波。短波范围包括最大测量能力不超过大约5km的装置。这种装置大多是电子光学类型的而且使用红外线，这种仪器很小、轻便、易于操作，适合于广泛的各种野外测量，并且被许多实践者所适用。 中波范围组的测量仪器延伸到100km，并且使用电磁波或者微波。尽管他们经常被用在精确大地测量中，也适用于土木工程和工程测量。更长的波长范围的仪器装置也能精确测量边长超过100km，但是他们不经常用在普通测量工作中，许多仪器的工作是靠传送长无线电波，但是一些是使用短波。他们主要被用在海洋或水路测量中，以及导航中大体上，EDM测量距离是通过比较一条未知长度的边到一条已知边，调制电磁波波长实现的。 这类似于一个需要的距离和测量钢R的校正。 电磁能通过大气依下列方式传播:v=fλ(1)其中v是电磁波的速度，单位是m/s ,f是电磁波的频率，单位是赫兹;λ是波长，单位是米。 使用EDM仪器频率可以被除数精确控制，但是速度是随着大气压力，温度 )式。为了精确的电子测距仪，和温度而变化的，这样，波长和频率必须遵从(1 大气压必须要按照上述情形测定校正。 EDM的装置，在A点通过铅垂线或光学器中。任选一个带有信号的电磁波，并且已经附加上一个参考频率或是可调制的。信号通过返回接收者，这样它的传播途径是AB距离的两倍。调制电磁波是通过一系列的不确定波长的波来表示 ，ooo的。在绘出的一些位置是通过象限角表示的起点是0，中是180，终点是360。 EDM装置在测量中，是通过测量相位变化来工作的，在这个过程中，反射 o波经历了一个360的相变。即使是正好分割一个测量边的两端为半个边长的倍数，如果距离正好为半个波长的整数倍，则相变为0，AB间相距8个半波长，此时相变为0，当边长不恰好是半个边长的整计算数倍时，通常情况下，通过仪器测量的小数部分为一个非0的相角或相变，如果一个已知精确的波长，小数部分可以转变成距离。 EDM直接能算出非整数波长，但是不能通过反射波的双倍路径计算元波经历的几个周期，这个不确定性被解决了，总之，通过传递低频和长波的附合信号来实文献 现的。 文献