Compass and Gyro-compass
I The Magnetic Compassed Magnetism
The principle of the present day magnetic compass is no different from that of
the compasses used by ancient mariners. It consists of a magnetized needle, or an
array of needles, allowed to rotate in the horizontal plane. The superiority of the
present day compasses over ancient ones results from a better knowledge of the laws
of magnetism which govern the behavior of the compass and from greater precision
in construction.
Any piece of metal on becoming magnetized will develop regions of concentrated
magnetism called. Any such magnet will have at least two poles of opposite polarity.
Magnetic force (flux) lines connect one pole of such a magnet with the other pole.
The number of such lines per unit area represents the intensity of the magnetic field
in that area. If two such magnetic bars or magnets are placed close to each other,
the like poles will repel each other and the unlike poles will attract each other.
Magnetism can be either permanent or induced. A bar having permanent magnetism
will retain its magnetism when it is removed from the magnetizing field. A bar having
induced magnetism will lose its magnetism when removed from the magnetizing field.
Whether or not a bar will retain its magnetism on removal from the magnetizing field
will depend on the strength of that field, the degree of hardness of the iron (Retentively), and also upon the amount of physical stress applied to the bar while
in the magnetizing field. The harder the iron, the more permanent will be the
magnetism acquired. II Terrestrial Magnetism
Consider the earth as a huge magnet surrounded by magnetic flux lines connecting
its two magnetic poles. These magnetic poles are near, but not coincidental with,
the earth’s geographic poles. Since the north seeking end of a compass needle is
conventionally cared the north pole, or positive pole, it must therefore be attracted
to a south pole, or negative pole. 。
Since the magnetic poles of the earth do not coincide with the geographic poles,
a compass needle in line with the earth’s magnetic field will not indicate true
north, but magnetic north. The angular difference between the true meridian (great
circle connecting the geographic poles) and the magnetic meridian (direction of the
lines of magnetic flux) is called variation. This variation has different values
at different locations on the earth. These values of magnetic variation may be found
on relevant chart, on pilot charts, and, on the compass rose of navigational charts.
The variation for most given areas undergoes an annual change, the amount of which
is also noted on charts.III Ship’s Magnetism
A ship under construction or major repair will acquire permanent magnetism due
to hammering and jarring while sitting stationary in the earth's magnetic field.
After launching, the ship will lose some of this original magnetism as a result of
vibration and pounding in varying magnetic fields, and will eventually reach a more
or less stable magnetic condition. The magnetism which remains is the permanent
magnetism of the ship.
The fact that a ship has permanent magnetism does not mean that it cannot also
acquire induced magnetism when pl aced in the earth’s magnetic field. The magnetism
induced in any given piece of soft iron is a function of the field intensity, the alignment of the soft iron in that field, and the physical properties and dimensions of the iron. This induced magnetism may add to, or subtract from, the permanent magnetism already present in the ship, depending on how the ship is aligned in the magnetic field. The softer the iron, the more readily it will be magnetized by the earth’s magnetic field, and the more readily it w ill give up its magnetism when removed from that field.
The magnetism in the various structures of a ship, which tends to change as a result of cruising, vibration, or aging, but which does not alter immediately so as to be properly termed induced magnetism, is called sub-permanent magnetism. This magnetism, at any instant, is part of the ship’s permanents magnetism, and consequently must be corrected by permanent magnet correctors. It is the principal cause of deviation changes on a magnetic compass. Subsequent reference to permanent magnetism will refer to the apparent permanent magnetism which includes the existing permanent and sub-permanent magnetism.
A ship, then, has a combination of permanent, sub-permanent, and induced magnetism. Therefore, the ship’s apparent permanent magnetic condition is subject to change from deperming, excessive shocks, welding, and vibration. The ship' induced magnetism will vary with the earth’s magnetic field strength and with the alignment of the ship in that field.
IV Induced Magnetism and Its Effects on the CompassInduced magnetism varies with the strength of the surrounding field, the mass of metal, and the alignment of the metal in the field. Since the intensity of the earth’s magnetic field varies over the earth’s surface, the induced magnetism in a ship will vary with latitude, heading, and heel of the ship.With the ship on an even keel, the resultant vertical induced magnetism, if not directed through the compass itself, will create deviations which plot as a semicircular deviation curve. This is true because the vertical induction changes magnitude and polarity only with magnetic latitude and heel, and not with heading of the ship, Therefore, as long as the ship is in the same magnetic latitude its vertical induced pole swinging about the compass will produce the same effect on the compass as a permanent pole swinging about the compass.
The earth’s field induction in certain other unsymmetrical arrangements of horizontal soft iron creates a constant A deviation curve. In addition to this magnetic A error, there are constant A deviations resulting from: ( 1 ) physical misalignments of the compass, pelorus, or gyro; (2) errors in calculating the sun' a azimuth, observing time, or taking bearings.The nature, magnitude, and polarity of all these induced effects are dependent upon the disposition of metal, the symmetry, or asymmetry of the ship, the location of the binnacle, the strength of the earth’s magnetic field, and the angle of dip.
Certain heeling errors, in addition to those resulting from permanent magnetism, are created by the presence of both horizontal and vertical soft iron which experience changing induction as the ship rolls in the earth' s magnetic field. This part of the heeling error will naturally change in magnitude with changes of magnetic latitude of the ship. Oscillation effects accompanying roll are maximum north and
south headings, just as with the permanent magnetic heeling errors.V Detailed Procedures for Compass AdjustmentThe Adjustment Check-off List gives the physical checks required before beginning adjustment. The adjustment procedure assumes that these cheeks have been completed. The navigator will avoid much delay by making these cheeks before starting the magnet and soft iron corrector adjustments. The most important of these checks are discussed below.Should the compass have a small bubble, add compass fluid through the filling plug on the compass bowl. If an appreciable amount of compass liquid has leaked out, check the sealing gasket and filling plug for leaks.Take the compass to a place free from all magnetic influences except the earth’s magnetic field for tests of moment and sensibility. These tests involve measurements of the time of vibration and the ability of the compass card to return to a consistent reading after deflection. These tests will indicate the condition of the pivot, jewel, and magnetic strength of the compass needlesNext, check the spheres and Flinders bar for residual magnetism. Move the spheres as close to the compass as possible and slowly rotate each sphere separately. Any appreciable deflection (2°or more) of the compass needles resulting from this rotation indicates residual magnetism in the spheres. The Flinders bar magnetization check is preferably made with the ship on an east or west compass heading. To make this cheek: (a) note the compass reading with the Flinders bar in the holder; (b) invert the Flinders bar in the holder and again note the compass reading. Any appreciable difference (2°or more) between these observed readings indicates residual magnetism in the Flinders bar. Spheres or Hinders bars which show signs of such residual magnetism should be annealed, i.e., heated tea dull red and allowed to cool slowly.
Correct alignment of the lubber’s line of the compass, gyro repeater, and pelorus with the fore-and-aft line of the ship is important. Any misalignment will produce a constant error in the deviation curve. All of these instruments may be aligned correctly with the fore-and-aft line of the ship by using the azimuth circle and a metal tape measure. Should the instatement be located on the centerline the ship, a sight is taken on a mast or other object on the centerline. If the instrument is not on the centerline, measure the distance from the centerline of the ship to the center of the instrument. Mark this distance off from the centerline forward or abaft the compass and place reference marks on the deck. Take sights on these marks
Align the compass so that the compass lubbers line is parallel to the fore-and-aft line of the ship. Steering compasses may occasionally be deliberately misaligned in order to correct for any magnetic errorAdjust the Flinders bar first because it is subject to induction from several of the correctors and its adjustment is not dependent on any single observation. To adjust the Flinders bar, use one of the following methods:：
Use deviation data obtained at two different magnetic latitudes to calculate the proper length of Flinders bar for any particular compass location.
If the above method is impractical, set the Flinders bar length by a. Using a Flinders bar length determined by other ships of similar structure; and b. Studying
the arrangement of masts, stacks, and other vertical structures and estimating the Flinders bar length requiredIf these methods are not suitable, omit the Flinders bar until the required data are acquired.
The iron sections of Flinders bar should be continuous and placed at the top of the tube with the longest section at the top. Wooden spacers are used at the bottoms of the tube.
Having adjusted, the length of Flinders bar, places the spheres on the bracket arms at an approximate position. If the compass has been adjusted previously, place the spheres at the position indicated by the previous deviation table. In the event the compass has never been adjusted, place the Spheres at the midpoint on the bracket arms.The next adjustment is the positioning of the heeling magnet using a properly balanced dip needle.
These three dockside adjustments (Flinders bar, quadrantal spheres, and heeling magnet) will properly establish the conditions of mutual induction and shielding of the compass. This minimizes the steps required at sea to complete the adjustment.
Before proceeding with the adjustment at sea the fallowing precautions, should be observed: secure all effective magnetic gear in the normal seagoing position; make sure the degaussing coils are secured, using the reversal sequence, if necessary.
The adjustments are made with the ship on an even keel, swinging from heading to heading slowly, and after steadying on each heading for at least 2 minutes to avoid Gaussian error. 。
Most adjustments can be made by trial and error, or by routine procedure. However, the procedures presented below provide analytical methods in which the adjuster is always aware of the errors ‘magnitude on all headings as a result of h is movement of the different correctors. Analysis Method
A complete deviation curve can be taken for any given condition, and an estimate made d all approximate coefficients. From this estimate, the approximate coefficients are established and the appropriate corrections are made with reasonable accuracy on a minimum number of headings. If the original deviation curve has deviations greater than 20°, rough adjustments should be made on two adjacent cardinal headings before recording curve data for such analysis.One-swing Method More often it is desirable to begin adjustment immediately, eliminating the original swing for deviation and the estimate of approximate coefficients. In this case the above problem would be solved by tabulating data and anticipating deviation changes as the corrections are made. Note that a new column d values started after each change is made. This method of tabulation enable the adjuster to calculate the new residual deviations each time a corrector is changed, so that a record of deviations is available at all times during the swing. Arrows indicate where each change is made.
VI Deviation Curves
The last step, after completion of either of the methods of adjustment, is to secure all correctors in position and to swing for residual deviations. These residual deviations are for undegaussed conditions of the ship, which should be
recorded together with details of corrector positions. On these swings, exercise extreme care in taking beatings or azimuths and in steadying down on each heading since this swing is the basis of standard data for the particular compass. If there any peculiar changeable errors, such as movable gens, listing of the ship, or anticipated decay from deperming, which would affect the reliability of the compass, they should also be noted on the deviation card at this time.
If the Flinders bar adjustment is not based on accurate data, as with a new ship, exercise particular care in recording the conventional Daily Compass Log data during the first cruise on which a considerable change of magnetic attitude occurs.
GPS, formally known as the NAVSTAR Global Positioning System, is operated and maintained by the United States Department of Defense. The National Space-Based Position, Navigation, and Timing Executive Committee manages GPS. The deputy secretaries of the Departments of Defense and Transportation lead the committee, which has a permanent staff that is responsible for the development of GPS.
GPS was initiated in 1973 to reduce the proliferation of navigation aids. By overcoming the limitation of many existing navigation systems, GPS became attractive to a broad spectrum of users. It was initially used as navigational aid by military ground, sea, and air forces. In more recent years, GPS has been used by civilians in many new ways, such as in automobile and boat navigation, hiking, emergency rescue, and precision agriculture and mining.
The GPS system was designed for 24 satellites. Each satellite lasts about ten years. Replacement satellites are placed in orbit regularly to ensure that at least 24 satellites are always functioning. The device that receives the GPS signal is knows as a receiver.
An atomic clock synchronized to GPS is required in order to compute ranges from these three signals. However, by taking a measurement from a fourth satellite, the receiver avoids the need for an atomic clock. Thus, the receiver uses four satellites to compute latitude, longitude, altitude, and velocity.
GPS has three components: the space component, control component, and user component.
The Global Positioning System (GPS) has changed the way the world operates. This is especially true for marine operations, including search and rescue. GPS provides the fastest and most accurate method for mariners to navigate, measure speed, and determine location. This enables increased levels of safety and efficiency for mariners worldwide.
It is important in marine navigation for the ship’s officer to know the vessel’s position while in open sea and also in congested harbors and waterway s. While at sea, accurate position, speed, and heading are needed to ensure the vessel reaches its destination in the safest, most economical and timely fashion that conditions will permit. The need for accurate position information becomes even more critical as the vessel departs from or arrives in port. Vessel traffic and other waterway hazards make maneuvering more difficult, and the risk of accidents becomes greater.
Accuracy of GPS receivers depends on four factors: (1) Selective Availability
(SA); (2) local environmental conditions; (3) autonomous mode versus RTCM mode, and (4) the averaging of recorded locations.
An enhancement to the basic GPS signal known as Differential GPS (DGPS) provides much higher precision and increased safety in its coverage areas for maritime operations. Many nations use DGPS for operation such as buoy positioning, sweeping, and dredging. This enhancement improves harbor navigation.
Mariners and oceanogrphers are increasingly using GPS data for underwater surveying, buoy placement, and navigational hazard location and mapping.
Governments and industrial, organizations around the world are working together to develop performance standards for Electronic Chart Display and Information Systems, which use GPS and/or DGPS for positioning information. These systems are revolutionizing marine navigation and are leading to the replacement of paper nautical charts. With DGPS, position and radar information can be integrated and displayed on an electronic chart, forming the basis of the Integrated Bridge System which is being installed on commercial vessels of all types.
GPS is playing an increasingly important role in the management of maritime port facilities. GPS technology, coupled with geographic information system (GIS) software, is key to the efficient management and operation of automated container placement in the world’s largest port facilities. GPS facilitates the automation of the pick-up, transfer, and placement process of containers by tracking them from port entry to exit. With millions of container shipments being placed in port terminals annually, GPS has greatly reduced the number of lost or misdirected containers and lowered associated operation costs.
GPS information is embedded within a system known as the Automatic Identification System (AIS) transmission. The AIS, which is endorsed by the International Maritime Organization, is used for vessel traffic control around busy seaways. This service is not only vital for navigation, but is increasingly used to bolster the security of ports and waterways by providing governments with greater situational awareness of commercial vessels and their cargo.
Finally, with the modernization of GPS, mariners can look forward to even better service. In addition to the current GPS civilian service, the United States is committed to implementing two additional civilian signals. Access to the new signals will mean increased accuracy, more availability, and better integrity for all users.
Ⅳ. Voyage Data Recorder
The voyage Data Recorder (VDR) are now commonplace in many forms of transport and have made a substantial contribution to the understanding of accident causes and the improvement of safety. The recorded data has enabled accident investigators to reconstruct events to identify precisely what went wrong and to ensure that effective, rather than convenient, recommendations can be made to prevent the same thing happening again. While many transport modes recognize the value of such devices, sections of the marine community have yet to be convinced. This reluctance to accept the value of data recorders and take positive measures to fit them in merchant vessels may be a contributory factor to the poor safety record of some ship owners today.
The air transport industry has led the way with data recorders. The mandatory
fitting of flight deck recorders and cockpit voice recorders in most commercial aircraft has made a major impact to the improvement of safety in the air.
Although there are same features that are common to both the air and sea transport industries, there are significant differences. Flights are measured in hours, voyages in days. Integrating a data recorder in the compact environment of and aircraft is one thing, fitting it into a merchant vessel is something entirely different, and the costs of so doing can be who see little or no commercial advantage to fitting then.
The safety record of some ship owners and flag states is far form satisfactory. In the past ten years about 1000 merchant ships have been lost and many more have been involved in lesser accidents to varying degrees.
Accidents can, and do, occur to vessels in any category and sailing under any flag. Leading flag states go to great lengths to establish the causes by fully investigating the circumstances and promulgating the findings for the benefit of all. States with independent accident investigation organization are recognized as being the most effective in view of their impartiality and the trend towards making marine accident reports public. Many nations, despite having large parts of the world’s fleet sailing under their flags, do little to fulfill the international requirement to investigate marine accidents when they occur. If an investigation is carried out there is, too often, little or no attempt to publish the report and any contribution to improving safety at sea is lost.
罗经和陀螺罗经
磁罗经和磁场
现代罗经使用的原则与过去海员所使用罗经的原则，没有什么不同。它包括一根磁针或者一列磁针，在水平面内旋转，现代罗经比古代罗经优越是由于对控制罗经的行为相关的磁学的规律有了更好的了解，还由于罗经制造时有了更好的精确度。
任意一根金属被磁化，是磁学发展的集中领域。任意这样的磁体都会至少有磁性相反的两极。磁感线将这种磁体的一极与另一极连接起来。单位区域内磁感线的密集程度可以表现出该区域磁场的强度。如果两条这样的磁铁或磁性物质被放置的很近，相同的极将互相排斥，不同的极将互相吸引。
磁性可以是永久性的，或者感应的。一根具有永久性磁性的磁铁当它从磁场中移出的时候将保持其磁性。一根具有感应磁性的磁铁当其从磁场中移出后将失去磁性。一根金属棒从磁场中移出后是否仍具有磁性取决于磁场的强度，铁的硬度（顽磁性）也取决于当其处于磁场中时时施加在其上的物理压力的大小。铁越是坚硬，它获得的磁性就越久。
地磁
把地球看作一个被连接其两极的磁场线所围绕着的巨大的磁场。这些磁极与地球地理上的两极相接近却并不重合。一根罗经指针红色的一极通
常被称为北极，或者阳极，它必定被南极或阴极相吸引
由于地球磁场的两极与地理的两极不完全重合，一根沿着地球磁场线的罗经指针将不会指向真正的北极，而是磁场的北极。这个在直子午线（过地理两极的大圆）与磁子午线（磁场线的指向）之间角度的差异称为地磁偏角。这个偏角在地球的不同地方有不同的值。地磁偏角的这些值会在相关的海图上，在引航员手，航运海图的罗经花上面可以找到。对于大部分已经给出值的地区这个偏差角发生着年度变化，这种年度变化也同时在海图上会标出。
船磁，在建或者大修的船舶长久地停在地球磁场里由于锤击辗轧将获得永久的磁性。在开锚起泊后，由于在变化着的磁场里振动和重击将失去这种原来的磁性，同时最终或多或少达到磁场稳定状态。剩余的磁性就是船舶永久的磁性。
事实上一艘拥有永久磁性的船舶并不意味着当它置于地球磁场时不能同时获得感应磁性。任何所给的软铁的感应磁性是磁场强度，软铁在磁场中的位置，及软铁的物理特性和形状的大小共同作用的结果。这感应的磁性可能增加或者削弱船舶已经具有的永久磁性，这取决于船舶在磁场中的定位。越软的铁，被地球磁场磁化越容易，当它离开那片磁场区域时失去这种感应磁性也越容易。
一艘船舶各种结构所具有的磁性，它会随着航行，振动，老化而趋于改变，但却不是立刻改变，以致这种磁性很恰当地被当作感应磁性，被称为半永久磁性。在任何时候这种磁性都是船舶永久磁性的一部分，所以必须利用永久磁铁修正器来修正。它是在罗经中引起罗经自差改变的最重要的因素。后来证明了对于永久磁性来讲，船舶现有的半永久磁性将影响船舶表面上的永久磁性。
一艘船舶是永久半永久和感应磁性的组合体。然而，船舶表面永久磁性的情况是随着过分摇荡，焊接和振动而磁性改变减少。船舶感应磁性也会随着地球磁场强度以及船舶在地球磁场中所处位置的变化而变化的。
感应磁性及其在罗经上的影响
感应磁性随着周围磁场的强度，金属的数量，金属在磁场中的定位的变化而变化。由于地球磁场强度在地球表面各不相同，船舶的感应磁场会随着纬度，船首向，船舶的纵横倾的变化而变化。
当船舶处于平吃水状态，合成垂直感应磁性如果没有通过罗经自身的处理，将会增加自差，该自差被绘画出来是一条半圆形的自差曲线。这是真实的，因为垂直感应强度改变磁
强度和极性，只与地磁纬度船舶倾侧有关，而与船首向的改变无关。因此，只要船舶在相同的地磁纬度，它的垂直感应磁极围绕罗经的摆动将在作为永久磁铁围绕罗经摆动在罗经上产生相同的影响。
在地球磁场中，水平软铁产生出不对称分布的恒定的自差曲线。这种恒定误差的存在是由于:（1）罗经，哑罗经，陀螺罗经的物理定位误差；（2）计算太阳方位角，观测时间，或获取方位的误差。
自然磁性和极性所有这些感应都取决于金属的倾向、船舶的对称性、罗盘箱的位置、地磁场的强度和俯视的角度。
倾斜角的误差除了由于船舶在地磁场的转动的水平或垂直的软铁引起的永久性的磁性外，这部分的倾斜
误差也随着船舶在地球纬度的变化而自然地改变，当船首向为南北向时，波动影响转动达到最大化，这也将引起固定磁体倾斜角误差。
磁罗经校正的详细程序
在校正之前需要给出一份校正列表，这些校正程序假设已经完成了，驾驶员在开始磁铁和软铁校正之前应尽量避免制作这些核对的拖延。这最重要的核对拖延如下：如果磁罗经中有水泡，需通过磁罗经盘上的塞子处填充液体，如果明显出现磁罗经液体的泄露，检查密封垫和填充塞子，以防泄露。
.把磁罗经放到除了地磁场远离其他磁场的地方，目的是测试瞬时敏感性，这试验涉及震动时间的测量和罗经导致读数一致偏差的能力，这试验也指出中心转轴、宝石轴承和罗针的磁力强度的情况。
接下来，为了其他领域剩余磁感应检查，夫林德棒，移动剩余范围使磁罗经尽可能靠近，慢慢的旋转使之分离出来，许多由于旋转而使罗针产生明显的偏角（2度或更多）估计在这个范围内的剩余磁感力。当船舶罗经首向为东西方向时，夫林德棒磁化，核对时更可取的。为了核对：（a）在支持器上的夫林德棒注释罗经读数（b）把夫林德棒反转过来再读一次罗经读数，在这些读书中的不同读数，估计夫林德棒上的剩余磁感力，感应剩余磁感应强度的其他领域和夫林德棒应被退化，热度边暗红，慢慢的变红，慢慢的冷却。
.修正磁罗经排列成行的长线，分罗经和船舶首尾哑罗经的线是非常重要的。在自差曲线中角度偏差将产生固定的错误，通过利用方位测定器和金属测深量度，所有的这些工具都可以正确的校准船舶的首尾线，这仪器位于船舶中心线处，一个看得到的中心线。为了标准上或者其他物体上，如果这仪器没有在中心线上，可确认船舶上的这条中心线与仪器之间的距离。标记从中心线或船尾的距离，查询在甲板上对应的标志并标记。
.对准磁罗经，使之对应的长线与船舶首尾线平行。为了修改磁罗经的错误，可以使磁罗经故意不对中。
校正夫林德棒首先是因为她可以引起不同的误差，它的调节不仅依靠单一的因素。校正夫林德棒用以下方法之一
用自差数据得到两种不同的磁纬度，选取许多特殊磁罗经的位置计算夫林德棒的本身长度。
如果上述方法行不通，用一个夫林德棒通过其他船相似的构造来确定夫林德棒的长度。通过研究排列的桅杆，烟囱排气管或其它垂直结构来估算夫林德棒的长度。
如果这些方法都不适合，忽略夫林德棒直到获得需要的数据。
夫林德棒的铁部件可以继续代替顶部最长的部件管，隔板被用于管的顶部。
如果已经校正了夫林德棒的长度，在概位上的托被臂，夫林德棒可以代替如果以前已经校正过，用之前自差的数据
可以指出代替这一领域。如果在这一项磁罗经从来没有校正过，用托被臂的中点处代替
接下来使用校正平衡的磁倾仪来校正倾斜角磁铁的位置。
这三个港区校正（夫林德棒，四分之一圆周区域，倾斜角磁铁）将证实与磁罗经互相作用和屏蔽的作用，这将切实减少在海上完成校正。
在海上校正这些程序之前应注意下列
预防措施：在一般适合远航当中应获得有效的磁力离合器，如有必要用反向轮换确保获得消磁圈。
这种校正是通过船舶在平吃水状态下缓慢地从船头转向船头并在船首位置至少停留两分钟避免高斯误差来实现的
许多校正可以通过试验和常规的程序获得然而这程序呈现以下供给的分析方法，这种方法调整者通过知道船首的移动可以得到不同的误差结果。
分析方法
单旋转方法
一个完整的自差曲线可以表示给定的状况，判断所有的近似系数，从这些估算中近似的系数是可以成立的。正确的修正可以精确地表示在船首上。如果传统的自差曲线已经偏离了远远超过20度，在分析记录弯曲数据之前粗略的校正将被用于两个相邻的船首。
除了原始的旋转偏差和近似系数估计之外立即校正时很有必要的，在这种情况下随着修正的进行，上面的问题将被制成表格和预测偏差所解决。随着每一项都在改变，一个新的用途框图的数据正在开始，这种制成表格的方法使每次校正估计新的剩余偏差都被改变，导致在所有时刻旋转，一个自差数据都可以利用，指针将会指示处哪里发生变化。
自差曲线.
在两种校对方法之一完成，最后一步是获得所有在工作的自差校正磁铁和旋转获得的剩余自差。这剩余自差是推测船舶状况，它应该与详细的定位校正记录在一起。
在这些旋转下，实际操纵中在获取方位或者方位角，在每次稳定航向中应该给与极大关注，由于这旋转对于特殊罗经是其标准资料的基础。如果存在任何奇怪的变化的误差，诸如，移动的炮弹，成列的船舶，或者预期磁性的减弱，这都将影响罗经的可靠性，这些都应该在本次航行的自差上标注出来。
如果夫林德棒校正不是基于精确的资料而是随着关注一艘新船，在磁纬度发生重大变化的处女航时，实际操纵中按惯例记录的罗经日志资料。
用自差数据得到两种不同的磁纬度，选取许多特殊磁罗经的位置计算夫林德棒的本身长度。
如果上述方法行不通，用一个夫林德棒通过其他船相似的构造来确定夫林德棒的长度。通过研究排列的桅杆，烟囱排气管或其它垂直结构来估算夫林德棒的长度。
如果这些方法都不适合，忽略夫林德棒直到获得需要的数据。
夫林德棒的铁部件可以继续代替顶部最长的部件管，隔板被用于管的顶部。
如果已经校正了夫林德棒的长度，在概位上的托被臂，夫林德棒可以代替如果以前已经校正过，用之前自差的数据
可以指出代替这一领域。如果在这一项磁罗经从来没有校正过，用托被臂的中点处代替这一区域。
接下来使用校正平衡的磁倾仪来校正倾斜角磁铁的位置。
这三个港区校正（夫林德棒，四分之一圆周区域，倾斜角磁铁）将证实与磁罗经互相作用和屏蔽的作用，这将切实减少在海上完成校正。
在海上校正这些程序之前应注意下列
预防措施：在一般适合远航当中应获得有效的磁力离合器，如有必要用反向轮换确保获
这种校正是通过船舶在平吃水状态下缓慢地从船头转向船头并在船首位置至少停留两分钟避免高斯误差来实现的
许多校正可以通过试验和常规的程序获得然而这程序呈现以下供给的分析方法，这种方法调整者通过知道船首的移动可以得到不同的误差结果。
分析方法
单旋转方法：一个完整的自差曲线可以表示给定的状况，判断所有的近似系数，从这些估算中近似的系数是可以成立的。正确的修正可以精确地表示在船首上。如果传统的自差曲线已经偏离了远远超过20度，在分析记录弯曲数据之前粗略的校正将被用于两个相邻的船首。
除了原始的旋转偏差和近似系数估计之外立即校正时很有必要的，在这种情况下随着修正的进行，上面的问题将被制成表格和预测偏差所解决。随着每一项都在改变，一个新的用途框图的数据正在开始，这种制成表格的方法使每次校正估计新的剩余偏差都被改变，导致在所有时刻旋转，一个自差数据都可以利用，指针将会指示处哪里发生变化。
自差曲线.在两种校对方法之一完成，最后一步是获得所有在工作的自差校正磁铁和旋转获得的剩余自差。这剩余自差是推测船舶状况，它应该与详细的定位校正记录在一起。
在这些旋转下，实际操纵中在获取方位或者方位角，在每次稳定航向中应该给与极大关注，由于这旋转对于特殊罗经是其标准资料的基础。如果存在任何奇怪的变化的误差，诸如，移动的炮弹，成列的船舶，或者预期磁性的减弱，这都将影响罗经的可靠性，这些都应该在本次航行的自差上标注出来。
如果夫林德棒校正不是基于精确的资料而是随着关注一艘新船，在磁纬度发生重大变化的处女航时，实际操纵中按惯例记录的罗经日志资料。
全球定位系统,正式称为了导航星全球定位系统,是由美国国防部操作和维护的。国家空间定位，导航和定时执行委员会管理全球定位系统。在国防部和交通等部门的部长领导这个委员会，其中有一个永久的工作，是为全球定位系统的发展负责。
在1973年发起的全球定位系统的导航，以减少艾滋病的扩散为目的。通过克服许多现有导航系统的限制，全球定位系统吸引了广泛的用户。它最初是作为军用陆，海，空三军的导航设备。在最近几年，全球定位系统已经在许多新的方面被民用，如汽车和船舶导航，远足，紧急救援，精确农业和采矿业。
GPS系统设计为24颗卫星。每颗卫星大约持续十年。备用卫星在轨道上有规律的排列以确保至少24颗卫星总是运作。该设备作为一个接收器接收GPS信号。
为了计算三个信号范围，原子时钟同步GPS是需要的。然而，通过从第四个卫星的测量，接收器避免了对原子时钟的需要。因此，接收器使用四颗卫星来计算经度，纬度，高度及速度。
全球定位系统有三个组成部分:空间的组成部分,控制组件,和用户组成部分。
全球定位系统（GPS）已经改变了世界的运作。尤其是对于海上作业，包括搜索和救援。GPS为船员驾驶提供了测量速度最快和最准确的方法，并确定位置。这使得全球范围内的航海安全和效率水平得到增强。
重要的是当在远洋航行和在拥挤的港口和航道时船上的人员知道船的位置。在海上，准确的位置，速度和航向，是确保船舶在最安全，最经济，最及时的到达目的地所必须的条件。船舶出发或靠港时对船舶精确位置的需求已经变得更加关键。船舶交通和其他水路危险使操纵更加困难，发生事故的风险变得更大。
GPS接收器精度取决于四个因素:(1)选择可用性(SA);(2)当地环境条件;(3)自主模式与RTCM模式,(4)有文字记载的平均地点。
增强的基本GPS信号被称为差分GPS(DGPS)在其电波范围内为海员的操纵提供更高的精度和安全性。许多国家,用DGPS操作如浮标定位、扫瞄、和疏浚。这加强、提高了港口导航。
海员越来越多地利用GPS数据进行水下测量、浮标的位置,和航海危险位置和绘制。
定位信息和/或差分全球定位系统作为定位信息。这些系统是革命性的海上航行，并导致纸质海图的更换。通过差分全球定位系统，位置和雷达信息能综合和显示电子海图，形成了目前正对所有商船安装的综合舰桥系统的基础。
各国政府和工业，世界各地的组织正在合作开发电子海图显示与信息系统，它使用GPS 定位信息和/或差分全球定位系统作为定位信息。这些系统是革命性的海上航行，并导致纸质海图的更换。通过差分全球定位系统，位置和雷达信息能综合和显示电子海图，形成了目前正对所有商船安装的综合舰桥系统的基础。
GPS在海上港口设施管理中扮演着越来越重要的角色。 GPS技术，结合地理信息系统耦合（GIS）软件，关键是有效的管理和世界上最大的集装箱港口设施布局的自动化操作。通过跟踪全球定位系统有助于他们从进港出口的回升，转让自动化和安置过程中的容器。随着集装箱运输在每年数百万被放在港口码头，全球定位系统，大大减少了丢失或误导相关的货柜数量，降低了经营成本。
在GPS信息嵌入在自动识别系统（AIS）的传输已知的系统。 AIS，是被国际海事组织认可的，用于繁忙的航道船只周围交通管制。这项服务不仅对导航至关重要，而且正通过为政府提供市区以及郊区情况的知晓，日益被用来支持港口和航道的安全。
最后，随着GPS现代化，船员可以期待更好的服务。除了目前GPS民用服务，美国正致力于实现两个额外的民用信号。信号的有权使用将意味着增加了准确性，更大的可用性和更好的完整性。
Ⅳ。航行记录仪
航行数据记录仪（VDR）现在在交通运输多种形式司空见惯，对事故原因的了解和安全的改善作出了重大贡献。记录的数据，使事故调查人推想事件准确地确定出了什么问题，并确保有效的，而不仅是方便的，建议可以被用于防止同样的事情再次发生。虽然许多交通工具认识到这些设备的价值，社会各界人士的海洋还没有被说服。这种不情愿接受的数据记录器的价值，并采取积极措施，以适应商船，他们可能是一个促成因素，今天一些船东的安全纪录欠佳。
空运行业利用数据录音已经走在前面。飞行甲板的座舱语音记录器记录仪和大多数商业飞机装配作出了强制性的装配，在改善空中安全上产生重大影响
虽然有同样的特征,都是很常见的空中和海上交通运输行业,有显著性差异。航班航行以小时为标准，航海则是以天为标准。在紧凑的环境集成数据记录仪和飞机是一回事，拟合成商船是完全不同的东西，而这样做，拟合拟合它们所需费用，很少有人看到或根本没有商业优势。
一些船东和船旗国的安全纪录，形式很令人满意。在过去的十年约1000艘商船已丢失，还有许多人在不同程度较轻的事故有关。
事故可以，而且做的，发生在任何类别的船只和在任何国旗下航行。领导船旗国竭尽全力通过对环境的充分调查发布发现所有人的利益的原因建立充分调查的情况。具有独立的事故调查组织成员国被公认为是最公正有效以及趋向海洋事故的公众报告。尽管有许多国家在世界的旗帜下，他们的船队航行的大部分地区，基本上没有履行国际海事组织在海事事故发生时的调查要求。如果有一份调查研究完成，往往很少或根本没有尝试发布报告和任何改善海上安全的贡献。
Exploring Filipino School Counselors’ Beliefs about Learning Allan B. I. Bernardo [Abstract] School reform efforts that focus on student learning require school counselors to take on important new roles as advocates of student learning and achievement.But how do school counselors understand the process of learning? In this study, we explore the learning beliefs of 115 Filipino school counselors who indicated their degree of agreementwith 42 statements about the process of learning and the factors thatinfluence this process.A principal components analysis of the responses to the 42 statements suggested three factors:(F1)social-cognitive constructivist beliefs, (F2) teacher-curriculum-centered behaviorist beliefs,and (F3) individual difference factors.The preliminary results are briefly discussed in terms of issues related to how Filipino school counselors’ conceptions of learning may guide their strategies for promoting student learning and achievement. [Key words]beliefs about learning, conceptions of learning, school counselors, student learning, Philippines School reform efforts in different parts of the world have focusedon students’learning. In particular,most school improvement programsnow aim to ensure that students acquire the high-level knowledge and skills that help them to thrive in today’s highly competitive globaleconomy (e.g., Lee & Williams, 2006). I n this regard, school reform programs draw from various contemporary theories and research on learning (e.g.,Bransford,Brown, & Cocking, 1999; Lambert & McCombs, 1998).The basic idea is that all school improvement efforts should be directed at ensuring students achieve high levels of learning or attainment of well-defined curricular objectives and standards.For example, textbooks (Chien & Young, 2007), computers and educational technology (Gravoso, 2002; Haertnel & Means, 2003;Technology in Schools Task Force, 2003), and educational assessment systems (Black & Wiliam2004; Cheung & Ng, 2007; Clark, 2001; Stiggins, 2005) are being reconsidered as regards how they can effectively provide scaffolds and resources for advancing student learning. Likewise,the allocation and management of a school’s financial resources are assessed in terms ofwhether these are effectively mobilized and utilized towards improving student learning (Bolam, 2006; Chung & Hung, 2006; Retna, 2007). In this regard, some advocates have also called for an examination of the role of school counselors in these reform efforts (Herr, 2002). Inthe United States, House and Hayes (2002) challenged school counselors to take proactive leadership roles in advocating for the success of all
Unit 1大规模研究发现：地球的“健康”每况愈下 有史以来对地球进行的最大规模的科学分析结果表明，地球上的许多生态系统都达不到标准。 由联合国主持的《千年生态系统评估综合报告》指出，由于不可持续的使用，地球上将近三分之二的用来维持生命的生态系统（包括干净的水源、纯净的空气以及稳定的气候）正遭受破坏。 以上大部分的破坏都是人类在过去的半个世纪里造成的。据报告分析，随着人类对食物、淡水、木材、纤维以及燃料等资源的需求日趋激增，环境发生了极大的变化，引发了诸如滥伐森林、化学污染等问题。因此，该报告的作者警告说，照此下去，本已岌岌可危的生态环境将会在21世纪的上半叶进一步恶化。 这项历史性的研究由来自世界95个国家的政府部门以及民间组织的1,300多位科学家共同完成。四年来，他们考察了地球上许多生物的生长环境、物种以及将他们联系起来的生态体系。联合国环境规划署对该报告进行了编辑整理并于昨天在中国北京公布了研究结果。 在公布该报告的新闻发布会上，联合国秘书长科菲·安南指出：“只有了解环境及其运作过程，我们才能制定出必要的措施加以保护它。”他还说，“只有珍惜所有宝贵的自然资源和人类资源，我们才有希望去建设一个可持续发展的未来。” 对社会经济的影响 该报告对自然界的大部分生物多样性持悲观态度，地球上可能有10%—30%的哺乳动物，鸟类以及两栖动物濒临灭绝。 这次大规模生态调查是根据安南的《千年发展目标》展开的，该发展目标是由联合国发起的，旨在2015年之前大幅减少饥饿与极度贫困等社会经济问题。 总部位于内罗毕的联合国环境规划署执行主席克劳斯·托普弗说：“从某些方面来说，《千年生态系统评估综合报告》让我们首次认识到生态系统服务功能的经济价值，并使我们对尊重和保护地球生命维护系统有了新的见解。” 目前由于人类社会对地球环境的开发利用，食物供应不断增加，然而增长的速度仍然太慢，难以完成联合国制定的在2015年之前消除全球一半饥饿人口的目标。 报告还说，过度使用生态系统的负面影响还包括渔业的衰退，含有大量沉积物的河口周围近海“死亡区”的出现，水质的变化以及不可预测的区域性气候等。 此外，森林的滥伐和其他生态系统的巨大改变也加剧了诸如疟疾、霍乱等疾病的传播，并使已有传染病分化出新的类别。
Chapter 1 Passage 1 Human Body In this passage you will learn: 1. Classification of organ systems 2. Structure and function of each organ system 3. Associated medical terms To understand the human body it is necessary to understand how its parts are put together and how they function. The study of the body's structure is called anatomy; the study of the body's function is known as physiology. Other studies of human body include biology, cytology, embryology, histology, endocrinology, hematology, immunology, psychology etc. 了解人体各部分的组成及其功能，对于认识人体是必需的。研究人体结构的科学叫解剖学；研究人体功能的科学叫生理学。其他研究人体的科学包括生物学、细胞学、胚胎学、组织学、内分泌学、血液学、遗传学、免疫学、心理学等等。 Anatomists find it useful to divide the human body into ten systems, that is, the skeletal system, the muscular system, the circulatory system, the respiratory system, the digestive system, the urinary system, the endocrine system, the nervous system, the reproductive system and the skin. The principal parts of each of these systems are described in this article. 解剖学家发现把整个人体分成骨骼、肌肉、循环、呼吸、消化、泌尿、内分泌、神经、生殖系统以及感觉器官的做法是很有帮助的。本文描绘并阐述了各系统的主要部分。 The skeletal system is made of bones, joints between bones, and cartilage. Its function is to provide support and protection for the soft tissues and the organs of the body and to provide points of attachment for the muscles that move the body. There are 206 bones in the human skeleton. They have various shapes - long, short, cube - shaped, flat, and irregular. Many of the long bones have an interior space that is filled with bone marrow, where blood cells are made. 骨骼系统由骨、关节以及软骨组成。它对软组织及人体器官起到支持和保护作用，并牵动骨胳肌，引起各种运动。人体有206根骨头。骨形态不一，有长的、短、立方的、扁的及不规则的。许多长骨里有一个内层间隙，里面充填着骨髓，这即是血细胞的制造场所。 A joint is where bones are joined together. The connection can be so close that no movement is possible, as is the case in the skull. Other kinds of joints permit movement: either back and forth in one plane - as with the hinge joint of the elbow - or movement around a single axis - as with the pivot joint that permits the head to rotate. A wide range of movement is possible when the ball - shaped end of one bone fits into a socket at the end of another bone, as they do in the shoulder and hip joints. 关节把骨与骨连接起来。颅骨不能运动，是由于骨与骨之间的连接太紧密。但其它的关节可允许活动，如一个平面上的前后屈伸运动，如肘关节；或是绕轴心旋转运动，如枢轴点允许头部转动。如果一根骨的球形末端插入另一根骨的臼槽里，大辐度的运动（如肩关节、髋关节）即成为可能。 Cartilage is a more flexible material than bone. It serves as a protective, cushioning layer where bones come together. It also connects the ribs to the breastbone and provides a structural base for the nose and the external ear. An infant's skeleton is made of cartilage that is gradually replaced by bone as the infant grows into an adult. 软骨是一种比一般骨更具韧性的物质。它是骨连结的保护、缓冲层。它把肋骨与胸骨连结起来，也是鼻腔与内耳的结构基础。一个婴儿的骨骼就是由软骨组成，然后不断生长、
https://www.doczj.com/doc/948926907.html,/finance/company/consumer.html Consumer finance company The consumer finance division of the SG group of France has become highly active within India. They plan to offer finance for vehicles and two-wheelers to consumers, aiming to provide close to Rs. 400 billion in India in the next few years of its operations. The SG group is also dealing in stock broking, asset management, investment banking, private banking, information technology and business processing. SG group has ventured into the rapidly growing consumer credit market in India, and have plans to construct a headquarters at Kolkata. The AIG Group has been approved by the RBI to set up a non-banking finance company (NBFC). AIG seeks to introduce its consumer finance and asset management businesses in India. AIG Capital India plans to emphasize credit cards, mortgage financing, consumer durable financing and personal loans. Leading Indian and international concerns like the HSBC, Deutsche Bank, Goldman Sachs, Barclays and HDFC Bank are also waiting to be approved by the Reserve Bank of India to initiate similar operations. AIG is presently involved in insurance and financial services in more than one hundred countries. The affiliates of the AIG Group also provide retirement and asset management services all over the world. Many international companies have been looking at NBFC business because of the growing consumer finance market. Unlike foreign banks, there are no strictures on branch openings for the NBFCs. GE Consumer Finance is a section of General Electric. It is responsible for looking after the retail finance operations. GE Consumer Finance also governs the GE Capital Asia. Outside the United States, GE Consumer Finance performs its operations under the GE Money brand. GE Consumer Finance currently offers financial services in more than fifty countries. The company deals in credit cards, personal finance, mortgages and automobile solutions. It has a client base of more than 118 million customers throughout the world
Unit 1 Genetically modified foods -- Feed the World? If you want to spark a heated debate at a dinner party, bring up the topic of genetically modified foods. For many people, the concept of genetically altered, high-tech crop production raises all kinds of environmental, health, safety and ethical questions. Particularly in countries with long agrarian traditions -- and vocal green lobbies -- the idea seems against nature. 如果你想在某次晚宴上挑起一场激烈的争论，那就提出转基因食品的话题吧。对许多人来说，高科技的转基因作物生产的概念会带来诸如环境、健康、安全和伦理等方面的各种问题。特别是在有悠久的农业生产传统和主张环保的游说集团的国家里，转基因食品的主意似乎有悖自然。 In fact, genetically modified foods are already very much a part of our lives. A third of the corn and more than half the soybeans and cotton grown in the US last year were the product of biotechnology, according to the Department of Agriculture. More than 65 million acres of genetically modified crops will be planted in the US this year. The genetic is out of the bottle. 事实上，转基因食品已经成为我们生活重要的一部分。根据农业部的统计，美国去年所种植玉米的1／3，大豆和棉花的一半以上都是生物技术的产物。今年，美国将种植6500多万英亩的转基因作物。基因妖怪已经从瓶子里跑出来了。 Yet there are clearly some very real issues that need to be resolved. Like any new product entering the food chain, genetically modified foods must be subjected to rigorous testing. In wealthy countries, the debate about biotech is tempered by the fact that we have a rich array of foods to choose from -- and a supply that far exceeds our needs. In developing countries desperate to feed fast-growing and underfed populations; the issue is simpler and much more urgent: Do the benefits of biotech outweigh the risks? 但是，显然还有一些非常现实的问题需要解决。就像任何一种要进入食物链的新食品一样，转基因食品必须经过严格的检验。在富裕的国家里，由于有大量丰富的食品可供选择，而且供应远远超过需求，所以关于生物技术的争论相对缓和一些。在迫切想要养活其迅速增长而又吃不饱的人口的发展中国家，问题比较简单，也更加紧迫：生物技术的好处是否大于风险呢? The statistics on population growth and hunger are disturbing. Last year the world's population reached 6 billion. And by 2050, the UN estimates, it will probably near 9 billion. Almost all that growth will occur in developing countries. At the same time, the world's available cultivable land per person is declining. Arable land has
高速视频处理系统中的信号完整性分析 摘要：结合高速DSP图像处理系统讨论了高速数字电路中的信号完整性问题，分析了系统中信号反射、串扰、地弹等现象破坏信号完整性的原因，通过先进IS工具的辅助设计，找出了确保系统信号完整性的具体方法。 关键词：高速电路设计信号完整性 DSP系统 深亚微米工艺在IC设计中的使用使得芯片的集成规模更大、体积越来越小、引脚数越来越多；由于近年来IC工艺的发展，使得其速度越来越高。从而，使得信号完整性问题引起电子设计者广泛关注。 在视频处理系统中，多维并行输入输出信号的频率一般都在百兆赫兹以上，而且对时序的要求也非常严格。本文以DSP图像处理系统为背景，对信号完整性进行准确的理论分析，对信号完整性涉及的典型问题[1]——不确定状态、传输线效应、反射、串扰、地弹等进行深入研究，并且从实际系统入手，利用IS仿真软件寻找有效的途径，解决系统的信号完整性问题。 1 系统简介 为了提高算法效率，实时处理图像信息，本图像处理系统是基于DSP+FPGA结构设计的。系统由SAA7111A视频解码器、TI公司的TMS320C6701 DSP、Altera公司的EPlK50QC208 FPGA、PCI9054 PCI接口控制器以及SBRAM、SDRAM、FIFO、FLASH等构成。FPGA是整个系统的时序控制中心和数据交换的桥梁，而且能够对图像数据实现快速底层处理。DSP是整个系统实时处理高级算法的核心器件。系统结构框图如图1所示。 在整个系统中，PCB电路板的面积仅为15cm×l5cm，系统时钟频率高达167MHz，时钟沿时间为0．6ns。由于系统具有快斜率瞬变和极高的工作频率以及很大的电路密度，使得如何处理高速信号问题成为一个制约设计成功的关键因素。 2 系统中信号完整性问题及解决方案 2．1 信号完整性问题产生机理 信号的完整性是指信号通过物理电路传输后，信号接收端看到的波形与信号发送端发送的波形在容许的误差范围内保持一致，并且空间邻近的传输信号间的相互影响也在容许的范围之内。因此，信号完整性分析的主要目标是保证高速数字信号可靠的传输。实际信号总是存在电压的波动，如图2所示。在A、B两点由于过冲和振铃[2]的存在使信号振幅落入阴影部分的不确定区，可能会导致错误的逻辑电平发生。总线信号传输的情况更加复杂，任何一个信号发生相位上的超前或滞后都可能使总线上数据出错，如图3所示。图中，CLK为时钟信号，D0、D1、D2、D3是数据总线上的信号，系统允许信号最大的建立时间[1]为△t。在正常情况下，D0、D1、D2、D3信号建立时间△t1<△t，在△t时刻之后数据总线的数据已稳定，系统可以从总线上采样到正确的数据，如图3(a)所示。相反，当信号D1、D2、D3受过冲和振铃等信号完整问题干扰时，总线信号就发生
第二部分 控制理论 第1章 1.1控制系统的引入 人类控制自然力量的设计促进人类历史的发展,我们已经广泛的能利用这种量进行在人类本身力量之外的物理进程?在充满活力的20世纪中,控制系统工程的发展已经使得很多梦想成为了现实?控制系统工程队我们取得的成就贡献巨大?回首过去,控制系统工程主要的贡献在机器人,航天驾驶系统包括成功的实现航天器的软着陆,航空飞机自动驾驶与自动控制,船舶与潜水艇控制系统,水翼船?气垫船?高速铁路自动控制系统,现代铁路控制系统? 以上这些类型的控制控制系统和日常生活联系紧密,控制系统是一系列相关的原件在系统运行的基础上相互关联的构成的,此外控制系统存在无人状态下的运行,如飞机自控驾驶,汽车的巡航控制系统?对于控制系统,特别是工业控制系统,我们通常面对的是一系列的器件,自动控制是一个复合型的学科?控制工程师的工作需要具有力学,电子学,机械电子,流体力学,结构学,无料的各方面的知识?计算机在控制策略的执行中具有广泛的应用,并且控制工程的需求带动了信息技术的与软件工程的发展? 通常控制系统的范畴包括开环控制系统与闭环控制系统,两种系统的区别在于是否在系统中加入了闭环反馈装置? 开环控制系统 开环控制系统控制硬件形式很简单,图2.1描述了一个单容液位控制系统, 图2.1单容液位控制系统 我们的控制目标是保持容器的液位h 在水流出流量V 1变化的情况下保持在一定 可接受的范围内,可以通过调节入口流量V 2实现?这个系统不是精确的系统,本系 统无法精确地检测输出流量V 2,输入流量V 1以及容器液位高度?图2.2描述了这 个系统存在的输入(期望的液位)与输出(实际液位)之间的简单关系, 图2.2液位控制系统框图 这种信号流之间的物理关系的描述称为框图?箭头用来描述输入进入系统,以及
GRA VITY RETAINING?WALL 1. INTRODUCTION Retaining walls are structures used to provide stability for earth or other material where conditions disallow the mass to assume its natural slope, and are commonly used to hold back or support soilbanks,coal or ore piles, and water. Retaining walls are classified, based on the method of achieving stability, into six principal types (Fig.1). The gravity-wall depends upon its weight, as the name implies, for stability. The cantilever wall is a reinforced-concrete wall that utilizes cantilever action to retain the mass behind the wall from assuming a natural slope. Stability of this wall is partially achieved from the weight of soil on the heel portion of the base slab. A counterfort retaining wall is similar to a cantilever retaining wall, except that it is used where the cantilever is long or for very high pressures behind wall and has counterforts, which tie the wall and base together, built at intervals along the wall to reduce the bending moments and sheers. As indicated in Fig.1c, the counterfort is behind the wall and subjected to tensile forces. A buttressed retaining wall is similar to a counterfort wall, except that the bracing is in front of the wall and is in compression instead of tension. Two other types of walls not considered further are crib walls, which are built-up members of pieces of precast concrete, metal, or timber and are supported by anchor pieces embedded in the soil for stability, and semigravity walls, which are walls intermediate between a true gravity and a cantilever wall. (a)(b)(e)
Table of Contents Uuit 1 What is Geomatics? （什么是测绘学） (2) Unit 2 Geodetic Surveying and Plane Surveying（大地测量与平面测量） (6) Unit 3 Distance Measurement（距离测量） (10) Unit 4 Angle and Direction Measurement（角度和方向测量） (14) Unit 5 Traversing （导线测量） (17) Unit 6 Methods of Elevation Determination（高程测量方法） (21) Unit 7 Robotic Total Station （智能型全站仪） (25) Unit 8 Errors in Measurement（测量工作中的误差） (29) Unit 9 Basic Statistical Analysis of Random Errors (32) Unit 10 Accuracy and Precision （准确度和精度） (35) Unit 11 Least-Squares Adjustment (38) Unit 12 Geodesy Concepts (40) Unit 13 Geoid and Reference Ellipsoid (42) Unit 14 Datums, Coordinates and Conversions (44) Unit 15 Map Projection (46) Unit 16 Gravity Measurment (48) Unit 17 Optimal Design of Geomatics Network (50) Unit 18 Construction Layout （施工放样） (53) Unit 19 Deformation Monitoring of Engineering Struvture (56) Unit 20 Understan ding the GPS（认识GPS） (59) Uuit 21 Understanding the GPS (II) 认识GPS(II) (62) Unit 22 Competition in Space Orbit（太空轨道上的竞争） (64) Unit 23 GIS Basics（GIS 的基础） (69) Unit 24 Data Types and Models in GIS GIS中的数据类型和模型 (75) Unit 25 Digital Terrain Modeling（数字地面模型） (79) Unit 26 Applications of GIS (83) Unit 27 Developments of photogrammetry (87) Unit 28 Fundamentals of Remote Sensing （遥感的基础） (90) Unit 29 Digital Image Processing and Its Applications in RS (94) Unit 30 Airborne Laser Mapping Technology（机载激光测图技术） (99) Unit 31 Interferometric SAR(InSAR) (102) Unit 32 Brief Introduction toApplied Geophysics (104) Unit 33 Origon of Induced Polarization (105) Unit 34 International Geoscience Organization (108) Unit 35 Prestigious Journals in Geomatics (110) Unit 36 Relevant Surveying Instrument Companies (115) Unit 37 Expression of Simple Equations and Scientific Formulsa (116) Unit 38 Professional English Paper Writing (119) Unit 39 Translation Techniques for EST (127)
文档简介 一，英语翻译经典文章之英文原稿二，中文翻译：这篇英语文章的最好翻译版本！不是俺说的，是俺老师说哒！！ 英文原稿Brian It seems my only request (“please, let me sleep”) is not clear enough, so I made this simple table that can help you when you’re in doubt. Especially during the night
中文翻译小子： 我只想好好地睡觉，你不明白吗？！所以，我做了这个简表。当你不知道怎么办时，特 别是在晚上的时候，你可以看看它。 具体情况行动指南 1，我正在睡觉禁止进入 2，你不确定我是否睡觉，你想搞清楚管你“鸟”事；禁止进入 3，你嗑了药，想奔向我的床你他妈的滚远点 4，你在youtube上看了一个超赞的视频，禁止进入；在脸书上把链接发给我想让我看看 5，就算第三次世界大战开始了管我屁事，他妈的别进来 6，你和你的基友们想和我“玩玩”抱歉，直男一枚。不要碰我的任何东西，门都别碰 7，你想整理我的房间我谢谢你了！我自己会打扫 8，普京宣布同性婚姻合法化终于等到“它”！还好你没放弃！还是不要来我房里！ 9，我不在家进我房间，想都别想 10，白天，我在家。你敲了门，我说“请进” 你可以进来了 福利放送！！
如果你已经看到了这里，那么说明你应该是英文爱好者哦。 下面有一些非常实用，我精心整理的英文资料，你一定用得到！快去看看吧！ 一，最常用英语翻译政治文体句型总结大全完美版 二，英文合同翻译最常用句型总结专业版 三，英语毕业论文提纲模板优秀完整详细无敌版
第一张机器人走进千家万户(1) 比尔﹒盖茨 设想一下:在一个新的产业诞生之际, 你目睹见证了这一切! 这个产业是在前所未有的新技术基础上发展起来的, 其中包括一些实力雄厚企业销售的高度专业化商务设备, 还有越来越多的新兴公司生产的新奇玩具、为玩具藏家青睐的机巧装置, 以及其他一些奇特有趣的特殊产品。但同时, 这还是一个缺乏行业标准和平台的、尚不成规模的产业。项目复杂, 进步缓慢, 实际应用更是少之有少。事实上, 尽管对这个产业的未来充满热情和希望,但是没有人能明确地说出什么时间- 或究竟是否有可能-它能取得关键性的规模发展。但是,若真能实现发展, 那么,它很可能改变整个世界。 当然, 上述描述可算是上世纪70 年代中期计算机产业的写照, 也就在那时, 保罗·艾伦和我成立了微软公司。当时,部分大企业、政府部门和其他一些机构都在使用笨重、昂贵的主计算机进行后台运算。知名大学和大型工业实验室的研究人员正试图建造出最基本的构件, 以使信息化时代的到来成为可能。当时因特尔公司刚刚推出他们的8080 微处理器,安他利公司正在销售一款流行电子游戏Pong 。而在一些自发组成的计算机俱乐部里,热忠于此的人们急切地努力探索这种新技术带来的好处究竟是什么。 但当时我脑海中所萦绕的则是更具前瞻性的问题:机器人产业即将作为一项新兴的产业而崛起,其当时的发展同30 年前计算机的发展如出一辙。想想看, 目前汽车组装线上使用的制造型机器人已替代了昔日的主计算机。这个产业其他的典型产品包括可进行外科手术的机器手, 在伊拉克和阿富汗用于路边及地面排雷的侦察机器人, 以及可以进行地板吸尘的家用机器人。电子产品公司还推出了可模仿人类、或是狗、恐龙等的机器人玩具, 而玩具收藏者们正迫不及待地想要猎取一套乐高公司生产的最新机器人系列玩具。 与此同时, 世界尖端科技人员正试图解决机器人技术中最棘手的难题, 诸如视觉识别、远程操控、以及学习型机器等问题, 而且他们正在不断获得成功。在2004 年美国国防部进步科技项目大挑战赛上(DARPA) ,产生了第一辆能够在美国加利福尼亚西南的莫哈韦沙漠142 英里的崎岖赛道上自主操控行驶的机器人车, 尽管获胜者制造的车
1、应力和应变 应力和应变的概念可以通过考虑一个棱柱形杆的拉伸这样一个简单的方式来说明。一个棱柱形的杆是一个遍及它的长度方向和直轴都是恒定的横截面。在这个实例中，假设在杆的两端施加有轴向力F，并且在杆上产生了均匀的伸长或者拉紧。 通过在杆上人工分割出一个垂直于其轴的截面mm，我们可以分离出杆的部分作为自由体【如图1(b)】。在左端施加有拉力P，在另一个端有一个代表杆上被移除部分作用在仍然保存的那部分的力。这些力是连续分布在横截面的，类似于静水压力在被淹没表面的连续分布。 力的集度，也就是单位面积上的力，叫做应力，通常是用希腊字母，来表示。假设应力在横截面上是均匀分布的【如图1(b)】，我们可以很容易的看出它的合力等于集度，乘以杆的横截面积A。而且，从图1所示的物体的平衡，我们可以看出它的合力与力P必须的大小相等，方向相反。因此，我们可以得出 等式(1)可以作为棱柱形杆上均匀应力的方程。这个等式表明应力的单位是，力除以面积。当杆被力P拉伸时，如图所示，产生的应力是拉应力，如果力在方向是相反，使杆被压缩，它们就叫做压应力。 使等式(1)成立的一个必要条件是，应力，必须是均匀分布在杆的横截面上。如果轴向力P作用在横截面的形心处，那么这个条件就实现了。当力P没有通过形心时，杆会发生弯曲，这就需要更复杂的分析。目前，我们假设所有的轴向力都是作用在横截面的形心处，除非有相反情况特别说明。同样，除非另有说明，一般也假设物体的质量是忽略的，如我们讨论图1的杆
一样。 轴向力使杆产生的全部伸长量，用希腊字母δ表示【如图1(a)】，单位长度的伸长量，或者应变，可以用等式来决定。 L是杆的总长。注意应变ε是一个无量纲的量。只要应变是在杆的长度方向均匀的，应变就可以从等式(2)中准确获得。如果杆处于拉伸状态，应变就是拉应变，代表材料的伸长或者延长如果杆处于受压状态，那么应变就是压应变，这也就意味着杆上临近的横截面是互相靠近的。 当材料的应力和应变显示的是线性关系时，也就是线弹性。这对多数固体材料来说是极其重要的性质，包括多数金属，塑料，木材，混凝土和陶瓷。处于拉伸状态下，杆的应力和应变间的线性关系可以用简单的等式来表示。E是比例常数，叫做材料的弹性模量。 注意E和应力有同样的单位。在英国科学家托马斯·杨(1773 ~ 1829)研究杆的弹性行为之后，弹性模量有时也叫做杨氏模量。对大多数材料来说，压缩状态下的弹性模量与处于拉伸时的弹性模量的一样的。 2、拉伸应力应变行为 一个特殊材料中应力和应变的关系是通过拉伸测试来决定的。材料的试样通常是圆棒的形式，被安置在测试机上，承受拉力。当载荷增加时，测量棒上的力和棒的伸长量。力除以横截面积可以得出棒的应力，伸长量除以伸长发生方向的长度可以得出应变。通过这种方式，材料的完整应力应变图就可以得到。 图1所示的是结构钢的应力应变图的典型形状，轴向应变显示在水平轴，对应的应力以纵坐标表示为曲线OABCDE。从O点到A点，应力和应变之间是