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In this paper, we will select and use stepper motor which is comparatively important and widely used in ships for the study. Through the study, we can propose a method that we can use the synchronous repeater compass for the high-precision digital conversion, and then statistics will be put into SCM AT89C52 with the simple handling of circuit conversion, thus, we can take a series of processes, such as data processing, initial value setting, directional displaying and serial port outputting. Foremost, the precision of this converting circuit can reach 0.1°that can ensure the numbers continuously change behind the decimal point one digit. So it is not only inexpensive, but also flexible and convenient in use.

This paper presented an automatic gain control (AGC) circuit suitable for FM/cw ladar. The proposed architecture was based on two-stage variable gain amplifier (VGA) chain with a novel DC offset canceller circuit, which contained an improved Gilbert cell and a Gm-C feedback loop. To keep the VGA with a linearity in dB characteristic, an improved exponential gain control circuit was introduced. The AGC was implemented in 0.18 μm standard CMOS process. Simulation and measurement results verified that its gain ranged from −20 dB to 30 dB, and bandwidth ranged from 100 kHz to 10 MHz. Its power consumption was 19.8 mW under a voltage supply of 3.3 V.

The technical and economic feasibility of high strength low alloy structural steel is analyzed used in highway semi-rigid guardrail. In principle of improving safety performance and reducing cost, a kind of high strength low alloy structural steel guardrail is designed. Through the finite element simulation method, the safety performance of this guardrail structure is validated to satisfy the grade-A conditions (160kJ kinetic energy). Compared with the guardrail of same protection level made of ordinary carbon structural steel, high strength low alloy structural steel guardrail can reduce the probability of penetrating when the accident vehicle impact the guardrail and decrease the accident damage, the steel consumption is above 20% lower and the construction cost can be saved as well, thus, remarkable economic and social benefits can be obtained.

The technology of OFDM is a multi-carrier technology, and it is a kind of high efficient modulation technique, it has the ability of strong anti multi-path propagation and frequency selective fading, and higher frequency spectrum utilization rate, this technology is applicable to high speed data transmission in the multi-path and fading channel environment. This paper introduces the basic principle of OFDM adaptive system, and the SNR estimation of OFDM adaptive system in Gauss channel through the simulation, this is a theoretical foundation to practical application in the future.

By analyzing the pattern and law which alternating magnetic field signals affect, the relations of alternating magnetic field signals and flaws were obtained. These relations illustrated alternating magnetic field technology ?s method and way. Some analysis was done after making contrast test samples. These analysis confirm that alternating magnetic field method can quickly find locations of defects during detection of blade part. It may raise efficiency and ensure equipments safely run.

The paper introduced grey comprehensive relational grade into transverse analysis and compare for several similar communication equipments. By analyze the grey relational principle, the relational coefficient, the selection of the distinguishing coefficient and studying several relational grades, the grey comprehensive relational grade is successfully applied to analysis of communication equipment fighting efficiency .Results of the practical application show that the method based on the comprehensive grey relational grade analysis has the advantages of simplified computation and feasible, consistency to the qualitative analysis result ,It can provides theoretical guidance for targeted maintenance of the equipment and improve and increase rapidly fighting efficiency of airborne early communication system in war.

In this study, bamboo ply panel (BPP) was exposed to 5 kinds of accelerate aging cycles in order to assess its durability under extreme conditions. Meanwhile, outdoor weathering, as a comparison, was carried out for 36 months with the objective of evaluating humidity resistance by means of testing modules of rupture (MOR) and modules of elasticity (MOE) value. Results show that for each kind of laboratory aging process, a comparison to wild field weathering was possible. Though very susceptible to hydrothermal alternation, BPP still kept good performance, the life span was about 15 months.

The altimeter is a very important measuring-height equipment, so the test of the altimeter is the important content to function measurement of the plane navigation system, synthetically altimeter detector can make some type altimeter test standardized, this paper introduces the overall design and system composition of the altimeter detector, it is focused on emphatically the hardware design procedure of the synthetical altimeter detector, this instrument can reduce about 30% work load of attendants, in the actual application the altimeter detector has advantages, such as good military and economic benefits.

The thermal fatigue cracking behavior of high Si−Mo nodular cast iron (NCI) is investigated by means of optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectroscope (EDS), in order to find a new material used in exhaust manifolds in First Automotive Works (FAW). Nodular cast irons with silicon content about 4.7%, in combination with up to 1.1% molybdenum, were produced by Jilin University and FAW. The repeated heating/cooling test was performed under cyclic heating at various maximum heating temperatures (Tmax) ranging from 800 to 900 °C. Experimental results indicate that the thermal fatigue cracking resistance of high Si−Mo NCI decreases with increasing the maximum heating temperature. The periods for crack initiation are 24—36, 40—50 and 70—90 times associated with heating temperature of 900, 850 and 800 °C, respectively, when the holding time is about 10 min at Tmax. When thermal fatigue cracking occurs, the cracking always initiates at the bigger surface of specimen. The major positions of cracks propagation are generally at the eutectic oxide boundary region and the region of the graphite disappearance. At the same time, the oxidation may accelerate crack initiation and propagation. On the other hand, micro-crack number varied from large to little because of shielding effect. As exhaust manifolds, the reasonable working temperature of high Si−Mo NCI is no more than 840 °C by test and analysis.

In order to analyze the feasibility of barrier safety performance evaluation with computer simulation method, finite-element models of various vehicles and barriers were set up and simulations results are compared to multiple full-scale impact test data. The results indicate that all safety performance index such as vehicle trajectory, structural adequacy, occupant risk and dynamic deformation can be extracted from computer simulation and FEA results are coincident with those of tests with error less than 10%. Computer simulation method is proved to be highly feasible for safety performance evaluation of barriers. The concept that simulation models must be verified through tests is stressed and the suggestion that laws and regulations on professional audit and management of CAE engineers should be completed is brought out.

A scannerless ladar imaging system based on a unique frequency modulation/continuous wave (FM/cw) technique is able to entirely capture the target environment, using a focal plane array to construct a 3D picture of the target. This paper presents a low power trans-impedance amplifier (TIA) designed and implemented by 0.18 μm CMOS technology, which is used in the FM/cw imaging ladar with a 64×64 metal-semiconductor-metal(MSM) self-mixing detector array. The input stage of the operational amplifier (op amp) in TIA is realized with folded cascade structure to achieve large open loop gain and low offset. The simulation and test results of TIA with MSM detectors indicate that the single-end trans-impedance gain is beyond 100 kΩ, and the -3 dB bandwidth of Op Amp is beyond 60 MHz. The input common mode voltage ranges from 0.2 V to 1.5 V, and the power dissipation is reduced to 1.8 mW with a supply voltage of 3.3 V. The performance test results show that the TIA is a candidate for preamplifier of the read-out integrated circuit (ROIC) in the FM/cw scannerless ladar imaging system.