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上 海 海 事 大 学 试 卷 2012— 2013 学年第一学期期末考试

《航海仪器》（A 卷）

班级 学号 姓名 总分

NB: Please write the appropriate answer in the Answer Sheet of Page 9 and 10.

I.Choose one most appropriate choice to complete the questions from 1 to 60.(1×60=60) 1. A free gyrcoscope means _______.

A．a three-freedom gyroscope that the gravity center coincides with its geometrical center B．a three-freedom gyroscope that spinning axis may point any direction in space C．a three-freedom gyroscope on which is without any application of the external torque D．a three-freedom gyroscope whose gravity center does not coincide with its geometrical center

2. When a three-freedom gyroscope rotates rapidly, its spinning axis remains _______; if an external torque is applied on its vertical axis, the spinning axis will _______. A．unchanged in celestial space; produce the precession B．unchanged in terrestrial space; produce the precession C．unchanged in celestial space; remain unmoved D．in the meridian plane; settle down the true north

3. Suppose the angular momentum of the spinning axis of a free gyroscope is settling to the true north, the northern end of the spinning axis will move _______if an external torque is applied on the west direction of the horizontal axis of the spinning axis. A．horizontally and eastwards B．horizontally and westwards C．vertically and upwards D．vertically and downwards

4. In the northern hemisphere, when the spinning axis of a free gyroscope is rotating rapidly, then _______. A． the angular velocity of the apparent movement is equal to the angular velocity of the earth’s

rotation B． the northern end of the spinning axis is deviating eastwards from the meridian plane and moving

upwards from the horizontal plane C． the northern end of the spinning axis is deviating westwards from the meridian plane and moving

downwards from the horizontal plane D． the northern end of the spinning axis is horizontally rotating 360 degrees per day

5. The trace of the spinning axis of a gyroscope under the influence of both the earth’s rotation and the controlling torque is _______.

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A．undamped ellipse B．undamped circle C．undamped hyperbola D．undamped spiral circle 6. If the structure parameters of a gyrocompass remain constant, the controlling torque is related to

_______. A．the latitude B．the azimuth C．the tilt D．the angular momentum

7. If the azimuth of the tilt of a gyroscope spinning axis is 5° and -5°, respectively, then the current position of its spinning axis can be determined _______. A．on the east of the meridian plane and above the horizontal plane B．on the east of the meridian plane and beneath the horizontal plane C．on the west of the meridian plane and above the horizontal plane D．on the west of the meridian plane and beneath the horizontal plane

8. The Schuler Tuning denotes that a gyrocompass does not suffer from the first type of ballistic error provided that the time period of an undamped ellipse of the gyrocompass is equal to _______. A．46.4min B．90.4min C．84.4min D．64.4min

9. The production of the controlling torque of Anschütz series gyrocompass is achieved by _______. A．vertically lowering the gravity center of the gyrosphere from the geometrical center of the gyrosphere B．attaching a fluid ballistic pots along the north-south direction above the balanceable gyroscope C．the electrically-operated pendulum D．vertically lowering the gravity center of the gyroscope from the geometrical center of the gyroscope

10. In order to enable the spinning axis of Sperry Type MK 37 gyrocompass to swing to the settling position after the damping movement, a damping iron weight should be attached on _______. A．the west of the follow-up element B．the west of the sensitive element C．the east of the follow-up element D．the east of the sensitive element

11. The heading transmission accuracy of a stepper system applied on a Sperry Type 37 gyrocompass is equal to________ degree. A．1/6 B．5/6 C．1.0 D．1.5

12. The purpose of the Arma-Brown Type 10 gyrocompass using two independent follow-up systems is to detect ______. A．the tank’s deviation from the position B．the tank’s deviation from the gyrosphere C．the gyrosphere’s deviation from the position D．the gyrosphere’s deviation from the celestial space

13. When a ship is changing the speed or altering the course, due to the influence of the inertia moment, the error caused by the spinning axis’s deviation from _______is so-called _______. A．the true north; the speed error B．the true north; the rolling error C．the settling position; the ballistic error D．the settling position; the latitude error

14. Suppose the equation of the gyroscope spinning axis is , where: H represents the angular momentum of the spinning axis, My represents the external torque applied on the OY axis, MZ represents the external torque applied on the OZ axis, ω1 represents the horizontal component of the earth’s angular velocity, ω2 represents the vertical component of the earth’s angular velocity, α represents the azimuth of the spinning axis, 𝜃 represents the tilt of the

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spinning axis. Then, the OY axis’s component of the angular velocity regarding the gyroscope spinning axis related to the celestial coordinate system is represented by _______. A． B．ω2 C． D．-ω1α

15. The Figure on the right shows the moving trace of the spinning axis of a free gyroscope located in the southern hemisphere whose horizontal axis and vertical axis are applied the controlling torque and the damping torque, respectively, where MM’ represents the meridian plane and HH’ represents the horizontal plane. Suppose u3 represents the linear velocity of the spinning axis created by the damping torque, then the direction of u3 of the Point P shown in the Figure is _______。 A．easterly B．westerly C．upward D．downward

16. Suppose a ship fitted a Sperry Type MK37VT gyrocompass is stably sailing in the calm waters of the southern hemisphere with the constant speed and course. The gyrocompass error is measured as 1.°2E. If all external signals are normally input into the gyrocompass, then this gyrocompass error is comprised by _______. ①the latitude error ②the speed error ③the ballistic error ④the rolling error ⑤the lubber error A．①② B．①②④ C．①②③④ D．⑤

17. After starting up the Anschütz Type 22 gyrocompass, what the digital monitor screen shows in the Figure means ______. A．the gyrocompass has already been settled down and the ship’s heading is 130.5° B．the gyrocompass is still heating the supporting liquid and the temperature of the supporting liquid is 130.5℃

C．the gyrocompass is seeking the true north and the ship’s heading is 130.5° D. the gyrocompass is still heating the supporting liquid and the ship’s heading is 130.5°

18. The normal working temperature of the supporting liquid in the Anschütz Type 22 gyrocompass is _______. A．52±3℃ B．45±3℃ C．45℃ D．50℃

19. As shown in the Figure, OXYZ means the free gyrocompass coordinate system, arrow R means the rotating direction of the gyro rotor with high speed. Suppose the initial direction of the spinning axis is matched with the positive direction of the OX axis. If an external force F is vertically and upwards applied on the positive direction of the OX axis, then the direction of the precession angular velocity of the angular momentum end of the spinning axis is on _______. A．the positive direction of the OY axis B．the negative direction of the OY axis C．the positive direction of the OZ axis D．the negative direction of the OZ axis

20. The gyrocompass speed error is to _______the compass structure and _______to the latitude direction. A．related; related B．related; irrelated C．irrelated; irrelated D．irrelated; related

21. The standard acoustic speed traveling in the seawater for a marine echosounder is designed as _______ m/s, and this speed is greatest influenced by _______. A．330, the seawater temperature B．1500, the seawater salinity

αθ

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C．330, the seawater salinity D．1500, the seawater temperature 22. Which kind of the sea bottom characteristics is the poorest reflection source to the ultrasonic pulse?

_______. A．mud B．rock C．gravel D．sand

23. Magnetostrictive transducer should be ________ for service after it had been powered off for ages. A．stagnated B．laserized C．polarized D．magnetized

24. The echosounder is able to properly display the water depth provided that the relationship between the echoes returned time of the maximum range (t) and the pulse repetition duration (T) is met as _______. A．t<T B．t>=T C．t>2T D．t=4T

25. The minimum range of a marine echosounder is dependent upon _______. A．the pulse repetition duration B．the transmitting frequency C．the acoustic speed D．the pulse length

26. The reason that the echosounder should not be used when a ship is going astern is that _______. A．the ship is suffering the heavy rolling B．the transducer surface is attached by the dirties C．the reflection of the sea bottom is reduced D．there are a lot of air bubbles existing in the seawater

27. The echosounder actually measures the echoed _______of the ultrasonic pulse. A．speed B．depth C．duration D．distance

28. The echosounder measures the depth between _______ and the sea bottom. A．the display B．the surface of the transducer C．the ship’s draft line D．the sea surface

29. The wave transmitted by the echosounder is _______. A．the continuous audio pulse B．the continuous audio wave C．the continuous ultrasonic pulse D．the ultrasonic pulse

30. The display of the marine echosounder shall be _______. A．graphically recorded B．digital C．flashing D．analogical

31. The device in charge of transmitting the ultrasonic pulse into the seawater in the echosounder is _______. A．the transmitting oscillator B．the pulse creator C．the transmitting transducer D．the indicator

32. Suppose the indicated depth is 100 meters when an echosounder is using under the 200-meter range, then the maximum allowable error for this echosounder is _______ meter. A．±0.25 B．±0.5 C．±2.5 D．±5.0

33. The echosounder transducer shall be installed on the position of the ship’s bottom . A．where the engine room, the propellers and the thruster shall be kept away as far as possible B．of 1/3 of the ship’s length from the bow C．between 1/2 to 1/3 of the ship’s length from the bow

D．located before the transducer of the Doppler speedlog but away from the direction of the 34. The relative log is to measure the ship’s speed and distance with the reference _______.

A．to the wind and the current B．through the water C．through the water and over the ground D．over the ground

35. Which of the following statements is incorrect in terms of the ship’s speedlog? _______.

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A．The acoustic correlation log may be an absolute log. B．The absolute log is a log capable of measuring the speed over the ground. C．The Doppler log can measure the speed over the ground. D．The shipborne electromagnetic log can measure the longitudinal speed and the athwartship speed of the ship.

36. The electronic signal output by the electromagnetic log’s sensor is_______to the ship’s speed through water. A．exponential B．logarithmic C．proportional D．inversely proportional

37. The transmission direction of the ultrasonic pulse from the acoustic correlation speedlog is _______. A．horizontally fore and aft B．downwards fore and aft C．vertically upward D．vertically downward

38. The Doppler log is working on the Doppler effect to measure the ship’s speed and the cumulative distance. The Doppler effect denotes that when the transmission and the reception are approaching each other, the frequency received by the receiver is _______ the frequency of the transmission source. A．more than B．less than C．equal to D．not affected by

39. The ship’s speed measured by the Doppler log is a function of _______. ①the transmitting frequency;②the pulse repetition frequency;③the pulse length;④the Doppler shift;⑤the acoustic traveling speed A．①②③ B．①②④ C．①④⑤ D．③④⑤

40. The purpose of using two acoustic beams in a Doppler log is _______. A．to measure the ship’s fore-and-aft speed B．to eliminate the error caused by the change of the acoustic traveling speed C．to eliminate the error caused by the ship’s rolling and pitching D．to measure the ship’s athwartship speed

41. The angle between the horizontal plane and the wave transmission for a Doppler log is normally _______. A．30º B．60º C．90º D．180º

42. _______is free from the change of the acoustic traveling speed in the seawater. A．The Doppler log B．The acoustic correlation log C．The echosounder D．None of all above

43. The measurement accuracy of the acoustic correlation log is dependent upon the correlation time delay and _______. A．the current speed B．the ship’s speed C．the acoustic traveling speed D．the distance between two transducers

44. The acoustic correlation log is able not only to measure the ship’s speed and the distance, but also to _______. A．measure the water depth B．detect the sea bottom characteristic C．detect the fish school D．detect the bearing of the dangerous object

45. Which of the following statements is most adequate for the current shipborne Doppler speedlog? _______. A．It only measures the speed over the ground. B．It only measures the speed through the water.

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C．It measures the speed over the ground in the shallow waters, but the speed through water in the deep waters. D．It measures the speed over the ground in the deep waters, but the speed through water in the shallow waters.

46. _______is able to indicate the ship’s speed, distance and the water depth. A．The electromagnetic log B．The Doppler log C．The water pressure log D．The acoustic correlation log

47. The Figure shows the scenario that a Doppler log system fitted on the ship is transmitting the ultrasonic pulses, then this kind of the Doppler log system is known as _______. A．one-element log B．two-element array log C．three-element array log D．four-element array log

48. The deviation of a marine magnetic compass is defined by the horizontal angle between_______and_______. A．the true north, the magnetic north B．the true north, the compass north C．the magnetic north, the compass north D．the ship’s lubber line, the compass north

49. Compared with the soft iron, the magnetization of the hard iron is _______ but the residual magnetism is_______. A．easier, more B．easier, less C．harder, more D．harder, less

50. The magnetic flux in the northern magnetic pole and the southern magnetic pole are defined as _______ and _______, respectively. A．negative, positive B．positive, negative C．negative, negative D．positive, positive

51. The magnetic dip is referred to as the angle between the lines of the terrestrial magnetic force and _______. A．the local magnetic meridian line B．the local geographical meridian line C．the local horizontal plane D．the local vertical plane

52. The magnetic compass will not suffer from the deviation when _______. A．the iron-made is in the dry dock B．fitted on the wood-made ship board C．fitted on the newly iron-made ship board D．fitted on the iron-made fishing vessel board

53. Which of the following alphabetic symbol is not used to represent one of nine soft irons on a marine magnetic compass? _______. A．a B．g C．i D．k

54. The curve connecting all points of the equal variation on the chart or the map is so-called _______. A．the variation curve B．the isogone C．the curve of the magnetic force D．the curve of the equal magnetic force

55. The main purpose of the magnetic compass card is to _______. A．hold the liquid B．store the correctors C．direct the course D．take the bearing

56. The specific proportions of the distilled water and the ethanol indigents included in the liquid in the bowl of the magnetic compass are _______, respectively.

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A．45％, 55％ B．55％, 45％ C．50％, 50％ D．35％, 65％

57. The “0” marking on the compass card of a magnetic compass fitted on an iron-made ship onboard denotes _______. A．the ship’s bow B．the true north C．the magnetic north D．the compass north

58. If the constant (fixed) deviation is negligible, the ship’s deviation should be corrected provided that the standard compass deviation is more than _______, and the steering compass deviation is more than _______. A．±1º, ±3º B．±3º, ±5º C．±5º, ±3º D．±5º, ±1º

59. When using the sun’s azimuth to measure the magnetic compass deviation, the sun’s height is preferable to be limited as less than _______. A．30 º B．45 º C．60 º D．90 º

60. ①②③④ shown in the Figure represent four different deviation correctors fitted in the magnetic compass, respectively, then the corrector used for correcting the heeling deviation is represented by _______。 A．① B．② C．③ D．④

II. Choose one appropriate choice from Choice Box to complete the questions from 61 to 74 regarding the working principle of the gyrocompass.(1×14=14) (NB: Two of Choices in Choice Box shall be selected twice.)

Choice Box A.the equiangular spiral curve B.beneath C.controlling torque D.eastwards E.horizontal(OY) F.vertical(OZ) G.damping torque H.above I.westwards J.precession K.the flat ellipse L.latitude

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III. Short Answer Questions 1. The technical parameters of four ranges of a shipborne echosounder is shown in the following Form, then

Range Pulse length (ms) Pulse repetition frequency (pulse/min) 1 0.25 750 2 0.38 375 3 1.00 150 4 2.00 75

(1) What are the maximum depth and the minimum depth of this echosounder, respectively? (1×4=4) (2) Suppose this ship is sailing with the even-keel draft of 10 meters in a fairway charted the sounding of 10.6 meters, which ranges of this echosounder may be selected in order to properly indicate the measured depth? (NB: The tidal height is ignored.) (1×8=8) 2.Simply describe how the electromagnetic speedlog works? (1×4=4)

3. List the conditions that the ship shall be swung to measure and correct the deviation of magnetic

compass.(1×10=10)

The earth’s rotation causes the apparent movement of the spinning axis of a free gyroscope with the property of the gyroscopic inertia:

Move 61 at the northern hemisphere and 62 the horizontal plane; Move 63 at the northern hemisphere and 64 the horizontal plane;

Use another gyroscopic property: 65 , apply the 66 on the 67 axis;

Then the trace of the spinning axis of the gyroscope is 68 to seek the true north;

Once again use another gyroscopic property: 69 , apply the 70 on the gyro;

For the Anschütz series gyrocompass, apply the damping torque on the 71 axis is known as the damping in azimuth; For the Sperry series gyrocompass, apply the damping torque on the 72 axis is known as the damping in tilt, but the 73 error is produced;

Then the trace of the spinning axis of the gyroscope is 74 to settle the true north.

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班级 学号 姓名 总分

答题卡 Answer Sheet

I． 1 2 3 4 5 6 7 8 9 10

11 12 13 14 15 16 17 18 19 20

21 22 23 24 25 26 27 28 29 30

31 32 33 34 35 36 37 38 39 40

41 42 43 44 45 46 47 48 49 50

51 52 53 54 55 56 57 58 59 60

II. 61 62 63 64 65 66 67 68 69 70

71 72 73 74

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