Calibration and compensation methods of installation error of electronic compass

Installation error angle is one of the factors that affect the accuracy of electronic compass used for geomagnetic navigation.To solve this problem,the calibration and compensation methods for installation error angle are studied.By analyzing the generation mechanism of installation error angle of electronic compass,an installation error model is established,compensation formulae are derived,and calibration scheme is proposed.To verify the correctness of the calibration and compensation methods,the verification experiment is conducted by computer simulation.The simulation results show that the proposed calibration and compensation methods are effective and practical.

Design of RCS measurement system based on hardgating

In accordance with the measurement requirements of radar cross section(RCS) in the nonstandard outdoor field,a RCS measurement system based on hardware gating was designed.In this paper,firstly the principle of hardware gating based on pulse measurement was introduced.Subsequently,the scheme of RCS measurement system and the design of out-door environment were presented.In the end,measurement results in an outer field were demonstrated.

Crystal Structure,Lattice Vibrational Characteristic,and Dielectric Property of Nd(Mg_(1/2)Sn_(1/2))O_3 Ceramic

Nd(Mg_(1/2)Sn_(1/2))O_3(NMS)ceramic was synthesized using a conventional solid-state reaction method.Crystal structure and morphology were investigated through X-ray diffraction(XRD)and scanning electron micrograph(SEM)technologies,respectively.Lattice vibrational modes

Plasmonically induced reflection in metal-insulator-metal waveguides with two silver baffles coupled square ring resonator

A plasmonic waveguide coupled system that is composed of a square ring cavity and a metal-insulator-metal （MIM） waveguide with two silver baffles is proposed. The transmission and reflection properties of the proposed plasmonic system are investigated numerically using the finite element method. The normalized Hz field distributions are calculated to analyze the transmission mode in the plasmonic system. The extreme destructive interference between light mode and dark mode causes plasmonically induced reflection （PIR） window in the transmission spectrum. The PIR window is fitted using the coupled mode theory. The analytical result agrees with the simulation result approximately. In addition, the PIR window can be controlled by adjusting structural parameters and filling different dielectric into the MIM waveguide and the square ring cavity. The results provide a new approach to designing plasmonic devices.

THz RCS measurement system

This paper presents the scheme,function and technical specifications of170-325GHz waveband radar cross sec-tion(RCS) measurement system.Some steps are taken to improve the performance of the system,including multilevel ampl-i fication and frequency multiplication,low-order harmonic mixing,using external signal generators and intermediary fre-quency(IF) receiver.Considerable dynamic range and other characteristics are obtained with these approaches.Finally,the concrete implementation and experiment of1mm RCS measurement system are described,and feasibility of the system stud-ied in this paper is verified.

Dynamic calibration method of capacitive pressure measuring device

This paper presents working principle,structure and a dynamic calibration method of capacitive pressure measuring device.Using this method,placing calibrated capacitive electronic pressure measuring device and three standard sensors in simulation chamber pressure generator is proper and the data generated by them are analyzed and compared.This calibration method realizes dynamic calibration of capacitive electronic pressure measuring device under actual working pressure;pressure signal and frequency spectrum are analyzed.The experimental results show that simulation chamber pressure calibration method is feasible.

Analysis of initial velocity measurement methods o f pro jectile muzzle

Because of the influence of conventio n al ammunition working in high rotation,high overloading,high temperature,hig h pressure and other harsh environments during the launch,it is difficult to m easure the initial velocity of projectile muzzle.This paper analyzes and compar es each sort of characteristics of several ty pical initial velocity measurement methods of projectile muzzle both at home and abroad,and proposes the development trend based on current research and practi cal aplication.

Micro capacitance detection circuit for MEMS capacitive sensor

With the development of micro-electr o-mechanical system(MEMS) technolog y,the MEMS-based capacitive sensor has been widely applied in the field of ele ctron components.However,the capacitance of the micromachined sensor is so sma ll that the detection of the smaller value change of the capacitance is a great challenge.Based on the principle of charging and discharging of the capacitor,a kind of pulse width modulated differential circuit is introduced in this paper.For subsequent amplification,a modified amplifier is presented.The different ial circuit converts the weak capacitance change to the change of the pulse widt h of the output voltage,and the linear relationship can be obtained.And the mo dified amplifier implements the processes of amplification and filtering synchro nously,and a large DC output voltage can be obtained by the lo w-pass filter.T he designed circuits have advantages as simplified circuit,high voltage stabili ty,perfect linearity and resolution.Besides,it is feasible to be integrated w ith the sensor to largely reduce the transmission error and interference.

A measurement system for YTO

Yttrium iron garnet(YIG)tuned oscillator(YTO),which is widely used in signal source,is difficult to be measured manually for its numerous parameters.In order to accomplish the measurement of YTO quickly and automatically,this paper gives the design of an auto-measurement system based on genernal purpose interface bus(GPIB).

Measurement of wireless pressure sensors fabricated in high temperature co-fired ceramic MEMS technology

High temperature co-fired ceramics(HTCCs) have wide applications with stable mechanical properties,but they have not yet been used to fabricate sensors.By introducing the wireless telemetric sensor system and ceramic structure embedding a pressure-deformable cavity,the designed sensors made from HTCC materials(zirconia and 96% alumina) are fabricated,and their capacities for the pressure measurement are tested using a wireless interrogation method.Using the fabricated sensor,a study is conducted to measure the atmospheric pressure in a sealed vessel.The experimental sensitivity of the device is 2 Hz/Pa of zirconia and 1.08 Hz/Pa of alumina below 0.5 MPa with a readout distance of 2.5 cm.The described sensor technology can be applied for monitoring of atmospheric pressure to evaluate important component parameters in harsh environments.

磁分离介孔TiO_2纳米复合材料用于吸附甲基橙（英文）

The adsorption of mesoporous Fe3O4–SiO2–TiO2(MFST), which can be separated easily from solution by a magnet, for the removal of methyl orange(MO) was investigated. The nitrogen adsorption–desorption measurement shows successful synthesis of MFST with an average pore size of 3.8 nm and a large specific surface area of55 m2·g-1. About 95% adsorption percentage of MO is achieved with an initial concentration of 10 mg·L-1in the dark and the MFST exhibits superior adsorption ability under acid conditions. The adsorption data fit well with the pseudo-second order model for adsorption. After 4 cycles, the adsorption rate for MO remains 74% in the dark and the MFST can be recovered in a magnetic field with a recovery of about 80 %(by mass). It demonstrates that the samples have significant value on applications of wastewater treatment.

标识分离映射网络的可扩展性和安全性研究(英文)

The locator/ID separation paradigm has been widely discussed to resolve the serious scalability issue that today's Internet is facing. Many researches have been carried on with this issue to alleviate the routing burden of the Default Free Zone (DFZ), improve the traffic engineering capabilities and support efficient mobility and multi-homing. However, in the locator/ID split networks, a third party is needed to store the identifier-to-locator pairs. How to map identifiers onto locators in a scalable and secure way is a really critical challenge. In this paper, we propose SS-MAP, a scalable and secure locator/ID mapping scheme for future Internet. First, SS-MAP uses a near-optimal DHT to map identifiers onto locators, which is able to achieve the maximal performance of the system with reasonable maintenance overhead relatively. Second, SS-MAP uses a decentralized admission control system to protect the DHT-based identifier-to-locator mapping from Sybil attacks, where a malicious mapping server creates numerous fake identities (called Sybil identifiers) to control a large fraction of the mapping system. This is the first work to discuss the Sybil attack problem in identifier-to-locator mapping mechanisms with the best knowledge of the authors. We evaluate the performance of the proposed approach in terms of scalability and security. The analysis and simulation results show that the scheme is scalable for large size networks and can resistant to Sybil attacks.

Synthesis of magnetic carrier sub-microparticles with high stability through carbon reduction and solation coating methods

This paper presents a novel approach in synthesizing SiO_2-Fe_3O_4magnetic carrier with high stability.The Fe_3O_4 magnetic powders were synthesized via onestep method named carbon reduction method. The advantages of the methods are of simple process, none lead-in pollution agent, low cost and adaptation to large-lot production. The stability of the magnetic powders is improved through modifying the Fe_3O_4 with SiO_2 in solation method.The results of the characterizations show that the superparamagnetic SiO_2-Fe_3O_4sub-microparticles（~600 nm）with saturation intensity of 36.4 m A·m^2·g^（-1）are obtained successfully. Moreover, the quantitating, repeatability and high stability of the carbon reduction method are demonstrated as well.

Design of shared bus DSP board in vector network analyzer

Currently,the mainstream vector network analyzer employs embedded computer module with a digital intermediate frequency(IF)board to form a high performance windows platform.Under this structure,the vector network analyzer needs a powerful encoding system to arbitrate the bus acquirement,which is usually realized by field-programmable gate array(FPGA)chip.The paper explores the shared bus design method of the digital signal processing(DSP)board in network analyzer.Firsty,it puts an emphasis on the system structure,and then the shared bus communication method is described in detail;Finally,the advantages of the shared bus communication mechanism are summanzed.

Dynamic mechanical behaviour of AZ31 magnesium alloy

To investigate the dynamic mechanical behavior of AZ31 Mg alloy,dynamic compression was carried out using a split Hop kinson pressure bar(SHPB) apparatus at strain rates up to 2.0×103 s-1,and d ynamic hardness was tested employing a dynamic hardness device at room temperatu re.Microstructural characteristic was analysed by optical microscopy.The dynam ic compression results demonstrate that AZ31 Mg alloy exhibits obvious yield phe nomena and strain hardening behavior at high strain rates.The basically same cu rvature of stress-strain curves shows a similar strain hardening rate.The dyna mic yield strength changes little,and the peak stress increases with the strain rates.The dynamic hardness test results indicate that the dynamic mechanical p roperties of AZ31 alloy sheet are anisotropic.The dynamic hardness increases sl owly with average strain for the 0° and 45° oriented samples.For the 90° ori e nted sample,dynamic hardness with strain increases rapidly first and then decre ases when the strain is more than 0.14.An examination by optical microscopy aft er high strain rate deformation reveals the occurrence of twinning,and the twin area percentage escalates with the strain rate increasing.

Design of Linear Sweep Source Based on DDS Used in Readout System for Wireless Passive Pressure Sensor

这篇论文建议高带宽上的设计和研究线性频率打扫基于目前广泛地被使用的相互的电感联合的原则在高温度涉及无线被动压力传感器的读出单位模块的信号来源。操作原则线性基于直接数字的频率合成(DDS ) 打扫频率来源技术被介绍，并且顺序的控制过程在我们的系统要求了的硬件电路和逻辑的实现方法被认识到利用这种技术。通过在步价值的不同条件下面的实验，联系的 sweep 范围和其它在联合传感器的相互的电感的读出系统期间设计指示物，对回声频率信息的抽取方法的影响，抽取精确性，和其它被分析并且学习。线性频率的设计扫信号来源在 1 MHz100 MHz 的 sweep 宽度以内为 0.116 Hz 与 6 kHz， 1 kHz 的最小的步值，和频率的精确的回声频率变化分辨率被认识到。由于综合商业芯片的使用，线性扫频率来源为更高的应用程序值模块化的读出单位在尺寸，高工作频率，高分辨率和低步值被使小。

The resonance frequency shift in an SOI nano-waveguide microring resonator

To research the effect of a deposited SiO2 insulating layer on the resonance frequency modulation of an SOI nanowaveguide ring cavity during integration fabrication, a rib waveguide ring resonator was systemati- cally designed and fabricated. SiO2 insulating layers with different thicknesses were deposited for analysis of the frequency shift characteristics. By testing the resonance transmission spectrum power of this structure, it is found that there are blue shifts after SiO2 deposition, and the frequency shift value of a structure with a 500 nm SiO2 insulating layer deposited is 0.8 nm, that is 0.24 THz at the resonance point where wavelength is around 1550 nm. Taking advantage of this conclusion, efficient optical modulation is available by choosing different frequency band resonance wavelengths to narrow the frequency modulation range.

An Arc Tangent Function Demodulation Method of Fiber-Optic Fabry-Perot High-Temperature Pressure Sensor

A new demodulation algorithm of the fiber-optic Fabry-Perot cavity length based on the phase generated carrier （PGC） is proposed in this paper, which can be applied in the high-temperature pressure sensor. This new algorithm based on arc tangent function outputs two orthogonal signals by utilizing an optical system, which is designed based on the field-programmable gate array （FPGA） to overcome the range limit of the original PGC arc tangent function demodulation algorithm. The simulation and analysis are also carried on. According to the analysis of demodulation speed and precision, the simulation of different numbers of sampling points, and measurement results of the pressure sensor, the arc tangent function demodulation method has good demodulation results： 1 MHz processing speed of single data and less than 1% error showing practical feasibility in the fiber-optic Fabry-Perot cavity length demodulation of the Fabry-Perot high-temperature pressure sensor.

Design of a Bionic Cilia MEMS three-dimensional vibration sensor

A biomimetic three-dimensional piezoresistive vibration sensor based on MEMS technology is reported. The mechanical properties of the sensor are analyzed and the static and dynamic characteristics of the sensor are simulated by ANSYS Workbenchl2.0. The structure was made by MEMS processes including lithography, ion implantation, PECVD, etching, etc. Finally, the sensor is tested by using a TV5220 sensor auto calibration system. The results show that the lowest sensitivity of the sensor is 394.7μV/g and can reach up to 460.2 μV/g, and the dimension coupling is less than 0.6152%, and the working frequency range is 0-1000 Hz.

Double-pass grating imaging spectrometer

A double-pass grating imaging spectrometer is proposed and demonstrated. The traditional entrance slit is replaced by a middle reflective slit, which is used as a spectral filter rather than a spatial filter. The light from the scene passes through the same dispersive grating twice. The full image of the scene can be obtained with a snapshot. Therefore, the stripe noise and image distortion caused by image mosaicking can be eliminated.Besides, the target is easier to be captured and focused, just like using a camera. This method can be used to obtain clearer spectral images of the scene conveniently and quickly.