Abstract:In this paper the efficient numerical methods for EM scattering from low observation targets have been introduced. These methods based on MLFMA and included some further improvements, among which the JMCFIE for surface integral equation of homogeneous dielectric scattering, the multi-TDS boundary conditions for volume integral equation of multi-layered dielectric scattering and their applications have been discussed in detail. Finally, the code, called as Parallelized Universal Electromagnetic Scattering Tool (P-UEST) and developed by our group for modeling of scattering from the stealth airplane, has been described. Some application examples have also been given in this paper.

Abstract:Transfer alignment is one of the key techniques in modern inertial guidance weapons. In this paper，principle of transfer alignment is introduced. Theory and methods in transfer alignment technology are thoroughly summarized，including error models of inertial navigation system，matching methods，observability analysis，filtering algorithms，error compensation techniques，simulation and experiment methods，et al. A usable mathematic model for transfer alignment is presented. From the point view of accuracy，rapidness and robustness，progresses of transfer alignment technology in the past few years are analyzed and synthesized. Difficulties and prospects in transfer alignment are also discussed.

Abstract:In this article, performance of estimation of signal parameters in PAssive Synthetic Array (PASA) is studied, focusing on the background of airborne platform intercepting narrowband microwave signals. Cramer-Rao Bound(CRB) of bearing is derived in case that none of bearing, frequency and amplitude is known. And a synthetic aperture selecting method is given to achieve the desired estimation precision. In addition, Maximum Likelihood(ML) estimator is derived for PASA. It is demonstrated that ML estimating error can converge to CRB quickly with increasing synthetic aperture length and Signal to Noise Ratio(SNR), but a threshold effect exists. The result is validated by computer simulation.

Abstract:The design of code tracking loop is a key sector of the realization of noncoherent spectrum spread receiver. In order to realize the code tracking in noncoherent spectrum spread receiver, an energy-normalization digital delay-locked loop was designed, the structure of the loop and the calculating procedure of loop parameters were introduced. The characteristic of noncoherent spectrum spread was analyzed first，and then the key point of the loop design was pointed out. Based on this, the design and realization methods of code loop discriminator, loop filter, early and lag code generator were expatiated. A set of specific loop parameters were introduced as well. Modelsim simulation results and FPGA actual measured data prove the precise code tracking ability of the design.

Abstract:The rapid development of programmable Graphics Processing Units(GPU) provides a new technical platform for the development of informationalized software radar terminal system. In this study， the powerful parallel processing capability and high computational efficiency of GPU were applied to improve the display system based on CPU, which greatly reduced the CPU utilization, reduced the burden of the system and obtained excellent display comparable with the hardware implementation of radar image display.

Abstract:Radar plays a great role in electronic antagonizing. The special characteristics of system and key technique problems needed to be solved on bistatic tracking radar of Transmitter-Receiver(T-R) type were analyzed. The time synchronization technique, the frequency synchronization technique and space synchronization technique between transmitter station and receiver station were introduced. The deficiency of traditional single range solving method was analyzed. Then two range solving methods based on adjusting the transmitted spring pulse and received range synchronization pulse were discussed. The time calibration methods on the measure value of bistatic radar were described. Finally the position precision of bistatic radar and the improvement on position precision of range by adopting networking multi-static radar system were studied. The simulation results show that the networked bi-(multi)static radar systems can apparently improve the ranging accuracy near the baseline by data fusion.

Abstract:A scheme of Margin Adaptive(MA)-based improved subcarrier and bit allocation was proposed for resource allocation in multiuser Orthogonal Frequency Division Multiplexing(OFDM) system. In order to decrease the transmit power of users and guarantee the fairness principle, subcarrier exchange for user Max-Min transmission rate was adopted as the principle, besides employing proportional fairness principle to allocate subcarriers for each user. Then, the bit was rounded by the greedy algorithm with the channel state information judgment, to obtain the minimized transmission power of the system. The analysis and simulation results show that the computational complexity of the proposed improved suboptimal algorithm is a little higher than that of the traditional step-by-step algorithm, but when compared to the optimal algorithm, the proposed algorithm is of almost the same performance and a far lower computational complexity.

Abstract:The Competitive Algorithm of Simulating Natural Tree Growth, a novel optimization algorithm, was applied to antenna design by calling the numerical electromagnetic simulation software based on Finite Element Method(FEM) to implement the automated antenna design, and then a novel microstrip plane tree-shaped antenna with end-fire characteristic was designed. This antenna maintained the end-fire radiation pattern with S11<-10 dB in the frequency band from 5.77 GHz to 5.93 GHz, and the end-fire gain is 5.4 dBi at the frequency of 5.8 GHz. According to the simulated result, a prototype of the antenna was fabricated and tested. Good accordance was obtained between simulated and measured results.

Abstract:This paper adopts the Method of Moment/ Finite Difference Time Domain(MoM/FDTD) hybrid technique in computational electromagnetism for analyzing the problems of shortwave antenna in complex environment. The models of shortwave dipole antenna in free space and on the ground are built, and the numerical simulation of the models is programmed with the hybrid technique. The comparison between the computing result by the hybrid technique and the result in the reference demonstrates the validation of the technique. Some good experiences are presented for improving shortwave antenna.

Abstract:The well-known “singularity” problem is one of the major defects in kernel-based video object tracking. However, the multiple-extreme problem is more general but has not been paid attention to. This paper studies this important problem and presents a novel approach called Section-Based Tracking (SBT) that is a kernel-based method with the section information provided by the division of the object’s weight image. SBT serves to eliminate fake extreme points and make the tracking process more robust. Besides, this new approach can also be naturally extended to deal with scale change and rotation. Experiments show that SBT method conduces to better performance in tracking process.

Abstract:In order to find an efficient adaptive algorithm，a new Mixed Variable Step Size ELMS algorithm(MVSS-ELMS) based on Extended Least Mean Square(ELMS) algorithm is proposed in this paper. This new algorithm combines the mean square error and the correlation of the error to modify the step size. The new algorithm has been improved in anti-noise capacity and effectiveness for it fitting the principal of adjusting step-size；meanwhile，it has the superiority in convergence rate and steady-state compared to Least Mean Square(LMS) and ELMS. Computer simulations indicate that the performance of the new algorithm is better than that of LMS and ELMS on Adaptive Noise Cancellation(ANC).

Abstract:Because quantification outcomes of primary performance parameter margins and uncertainties are inputs to a Quantification of Margins and Uncertainties(QMU) analysis，the method research of quantifying performance parameter margins and uncertainties plays an important role in QMU. In this paper, relative computing methods for figures of merit are presented according to different expressions of performance margin outcome. The changing trend of the key performance parameters over time for some component is determined by test data. The general method of quantifying performance parameter margins and uncertainties based on statistics theory is proposed. At last a relative example is introduced.

Abstract:Large templates and multi-range-gate relation arithmetic is highlighted in the application of purview movement analysis due to its excellent stability and accurate calculation under the situation of low Signal to Noise Ratio(SNR) and with more models in image. Aiming at real-timing requirement of large templates and multi-range-gate relation calculation, this article presents a kind of parallel pipelining calculating structure. The structure can calculate normalized relation using the template as large as 32×32 in real time when inputted in digital video coding of ITU656. Meanwhile the structure can change the templates in real time according to the position information of the image in the video coding to realize multi-range-gate searching. The results of experiments show that the structure of relation calculation has resolved the real time problem effectively just with a delay of 1.04 μs.

Abstract:To build a simple-lead Fetal Electro Cardio Graph(FECG) extraction system, a simple lead-based weak-signal programmable front-end amplifier design method is presented. The introduction of Automatic Gain Control(AGC) method can adjust the total magnification at the range of 10 000 when the output signal amplitude is relatively stable. The fitting of the relationship between the signal and magnification can be recorded automatically; the automatic gain range is up to 69 dB. This method can ensure that the details of the mixed-signal in the maternal abdominal wall will not be lost and will be easy to recover. Engineering application tests show that clear fetal ECG image can be obtained for fetal ECG extraction by using this amplifier.

Abstract:In multiple sensor measurement and control system，there exists nonlinearity relationship between the tested coefficients and relevant parameters. A kind of model and algorithm of multiple sensor information fusion based on Genetic Algorithm and Least Squares Support Vector Machine(GA-LSSVM) are proposed in this paper. For improving accuracy of the model，genetic algorithm is recommended for parameter optimization because of its excellent global optimization ability. It is an effective way for modeling multiple sensor system of small sample, nonlinearity and high dimension. To verify the effectiveness of this method，a simple low-voltage load circuit system is adopted as an example，and the result shows that the model and algorithm have certain superiority in measuring precision and are easy to be promoted.

Abstract:For traditional watermarking techniques based on fractal coding, watermarking format is limited to binary sequence 0,1, thus incapable of gray-scale image embedding. In this paper, a novel algorithm feasible for gray-scale watermarking embedding is proposed. To embed watermarking directly into decoding parameters, the host image is encoded with orthogonal fractal coding techniques. Because of the mean-invariant characteristics of fractal encoding parameters during iterations, the watermarking can be embedded into them. On the other hand, fractional calculus pseudo-random sequence has solved the problem that how to enhance the security of embedded watermarking and makes it possible for gray-scale watermark to be embedded during fractal encoding process. Experimental results indicate that proposed algorithm brings little contamination upon the original image，and the extracted watermarking is of good quality. The encryption for gray-scale watermark with fractional differential sequence shows good performance.

Abstract:This paper summarizes the relay twitter test in details，and explains the function of instantaneous switching instrument during this test. On the basis of analyzing the working principle and wave collection process of instantaneous switching instrument, the change law of on-off action for relay contact is concluded. The method simulating the action of relay in measuring instantaneous switching instrument is proposed. A set of general instrument for measuring these kinds of devices is established.

Abstract:Bulk acoustic wave filter fabricated by Complementary Metal Oxide Semiconductor(CMOS) is of high-quality factor and small size，which is better than Surface Acoustic Wave(SAW) Bulk acoustic wave filters. It has been used to take the place of conventional Radio Frequency(RF) filters for its outstanding performance and price advantage. The Modified Butterworth-Van Dyke(MBVD) model was built to analyze the frequency response of bulk acoustic wave filters. A kind of ladder RF bulk acoustic wave filter layout was designed. Based on the layout of the filter，the frequency characteristics of the varied ladder filters centering on 1.99 GHz with bandwidth 56 MHz were simulated by MBVD model and the out band attention of 4-order filter was about -29.708 dB. The tested transmission characteristics of 2-order and 3-order ladder filters fabricated by Micro Electro Mechanical Systems(MEMS) agreed well to the simulation results which indicated the broad application. The simulation results can provide a reference for designing the bulk acoustic wave filter.

Abstract:This paper presents a decoupled micromechanical gyroscope with dual frames. The robust structure considering fabrication errors is obtained by the use of optimal robustness of design and process compensation. Experimental results show that the quality factor of driving mode is more than 2 000，while the quality factor of sensing mode is more than 800；and the range is 2 400°/s，the sensitivity and linearity of the fabricated gyroscope are 1°/s and less than 0.3% respectively.

Abstract:In the Cognitive Radio(CR) network, the opportunistic spectrum sensing and access is of paramount importance to the primary user’s capacity. This paper propose a multi-user Decentralized Partially Observable Markov Decision Process(Dec-POMDP) CR spectrum access algorithm. In this framework, adjacent CR users exchange access policies with neighbors, and according to policy gradient, each local CR user adjusts its own access policy till the system of CR network obtains an optimum joint access policy. Simulation results show that this algorithm can lower the capacity loss of authorized user efficiently and improve spare spectrum efficiency, moreover, it can make access decision more efficiently.

Abstract:Mobile Ad Hoc network features itself as self-organizing，multi-hop wireless network and this give rise to challenges for the network design，including high network energy efficiency consideration because typical applications of Mobile Ad Hoc network often assume limited power resource of network participants. At the beginning，current research status of energy-efficient technique in Mobile Ad Hoc network is summarized. Then based on the analysis of Energy-consume Model for data transmission in wireless network，principles for the energy-efficient design for wireless Ad Hoc network both in Media Access Control(MAC) layer and network layer are introduced. Finally，Further improvement on energy saving should consider cross-layer design.

Abstract:In Wireless Mesh Networks(WMNs) for Internet access, service quality of different users will vary greatly depending on the locations of users. In this study, WMNs were simulated as queuing networks and the delay variance of different users in unsaturated load case were analyzed. The analytical results indicated that delay fairness could be guaranteed by setting multiple buffers in mid-node and scheduling priorities of all flows. The priority assignment problem was formulated as a combinatorial optimization problem which was targeted to achieve maximal fairness, and a solution was also provided. The fairness was evaluated by using Lorenz curve. Simulation results show that better fairness index can be acquired by using optimal assignment algorithm.

Abstract:Power Line Communication(PLC) provides a low-cost data communication platform for automation system of electric distribution network. However，in PLC network，the characteristics of time-varying，high attenuation and high noise of the channel，have caused some problems like short distance of communication and poor reliability. It is quite difficult to resolve these problems at the physical layer，whereas they can be solved through the upper communication protocol. This paper proposes an adaptive routing algorithm，through which the routing among the nodes can be obtained，and the broken links can be repaired. The simulation results indicate that the algorithm is a simple and effective method of extending the communication distance and improving the reliability of PLC.

Abstract:In traditional wireless communication, due to the interference of the external environment and channel instability, the outage probability of network is high. The communication performance is poor under bad channel condition. In this paper, the network performance is improved through the cooperation among wireless nodes. The performance of wireless channel is enhanced in direct transmission through relay of different nodes(amplification, decoding, or the network coding). The network outage probability is reduced with the use of decode-forward and network coding forward. The proper forward method can be found by the comparison of the outage probability under different spectral efficiencies. Simulation results indicate if the spectral efficiency is less than some certain value, the performance of amplify-forward and network coding forward are much better than that of direct transmission.

Abstract:Effective knowledge modeling is one of the key issues in Cognitive Radio(CR). This paper proposes an ontology-based model for CR knowledge representation. Concept extraction and class analysis is performed for CR knowledge described by natural language，and web ontology language is adopted to implement the ontology of CR knowledge. Then reasoning is conducted with the ontology. The experiment result shows that the proposed method supports knowledge sharing and reuse，can integrate heterogeneous radio knowledge，and enables CR to understand their own state and external environment，which provides the basis for CR reconfiguration in decision-making.

Abstract:The report of some test equipment is discommodious for users because its format is fixed and unmatched with the document criterion of users. User-oriented report scheme of test equipment is introduced in this paper. Through the test equipment software programmed by Visual C++，users can get the data stored in the database by ActiveX Data Objects(ADO)，and make a report with the report template of Microsoft Office Word. If the amount of test data is definitely，user can customize the format of report by changing the report template of Microsoft Office Word. This scheme can improve the design efficiency of software，and is convenient for use.