Traditional edge extracting methods are sensitive to image noise, and discontinuities often occur in extracted edges. This paper presents an edge leading ant colony algorithm to suppress the noise for edge extraction in noise image. Firstly, it detects the possible edge points which include the real edge points and the noise points. Then, the information of possible edge points is used as heuristic measure to guide iteratively searches of ants to get local edge points. In each cycle, pheromones on the traversed route of each ant are updated proportional to the length of the route, and the searching routes converge on real edges progressively based on the pheromone updating rule. Finally, real edges can be extracted according to the intensity of pheromones. Compared with traditional ant colony algorithms, the proposed method uses leading information to guide the searching process of the ants, which enhances the intention of the search, and improves the efficiency of the algorithm. Experimental results on noise images show that the method can extract real edges effectively, which keeps the edge details and suppresses the noise at the same time.

Most learning-based super-resolution algorithms neglect the illumination problem. In this paper, a new image representation called Logarithmic-Wavelet Transform (Log-WT) is developed for the elimination of the lighting effect in the image. Meanwhile, a Log-WT based method is proposed to combine super-resolution and shadow removing into a single operation. In this method first intrinsic, illumination invariant features of the image are extracted with exploiting logarithmic-wavelet transform. Then an initial estimation of high resolution image is obtained based on the assumption that small patches in low resolution space and patches in high resolution space share the similar local manifold structure. Finally the target high resolution image is reconstructed by applying the special face constraints in pixel domain. Experimental results demonstrate that the proposed method simultaneously achieves single-image super-resolution and image enhancement especially shadow removing. After that, reconstruction results are used for face recognition which improves the recognition rate.

Palm line structure features are clear and stable, and they can uniquely describe a palmprint. Because the directions of palm lines are arbitrary and irregular, it is very difficult to accurately represent their structure features with an expression. This paper presents a new approach to line structure features representation and matching for palmprint recognition. It uses improved water-filling algorithm to extract the statistical structure features and direction structure features and label palm lines direction information from the extracted palm lines image. Finally, the extracted global statistical structure features and local detail direction structure features are combined as a feature vector, which is used in the next recognition. The experimental results show the method not only has a good property in matching, but also it can get a better accuracy.

Due to a large variation in the quality of froth images of ore and inhomogeneity of size, shape and grayscale of bubbles, a new segmentation method based on clustering pre-segmentation and high-low scale distance reconstruction is proposed for froth images. Firstly, the segmentation between foreground froth and background mineral slurry image is achieved by the k-means clustering method and the noises are filtered according to intensity distribution and shape distribution information, and a new reconstruction combined with high-low scale distance transformation based on morphological reconstruction is presented and applied to the froth distance- transformation image. Then the precise region makers for watershed transformation are extracted by area-reconstruction h-dome improved transformation. Finally, the watershed algorithm is used to get waterline for every bubble. Bubble physical characteristics such as the bubble number and bubble size can be obtained from the segmented image,which provide the guidance for flotation control process. The experimental results show its effectiveness.

To a mass of computation iteration of Chambolle model in solving the inverse problem of image zooming, a class of new model that is based on Besov space is put forward. The new model translates the variational problem that is solved into a sequence based wavelet field through the equivalence between Besov semi-norm and the norm of wavelet coefficients. And the process of minimization shows that the optimization solutions of the sequence can be represented as the orthogonal projection onto wavelet field. Finally, not only the zoomed images have sharper and smooth edges, but also the details of images are kept, resulting in the naturalness. In addition, the effect of denoising is very satisfactory.

To solve the problem of capturing only limited directional information in image edge detection method based on space domain or wavelet transform domain, the Contourlet transform with parabolic scaling and sufficient directional vanishing moments is used to represent discontinuous curves in nature images more efficiently. The algorithm detecting modulus maxima in Contourlet subbands has lower computation complexity, because Contourlet subbands obtain much more directions than wavelet subbands. Experimental results demonstrate that the proposed scheme is superior to the scheme based on wavelet modulus maxima by approximating better the edges of images.

Considering the computational complexity of particle filtering, based on the time-observation state space model, a new fast algorithm with low computational complexity is developed for DS-CDMA blind multiuser detection using particle filtering in synchronous systems over flat and fast fading channels. This algorithm classifies the particles when its number exceeds the threshold, and the probability difference of different particles is taken as the criterion whether the particles number is enough, and then the particles number under different circumstance is adjusted adaptively; meanwhile the performance of blind multiuser detection under distinct probability difference of different particles is discussed. Simulation results confirm that this algorithm effectively decreases computational complexity and well remains the performance of blind multiuser detection, meanwhile the performance in proportion to the probability difference.

There is scarcely any ideal singular signal in engineering practice and the singularity of engineering signal is always very fuzzy. Wavelet’s detection mechanism for this kind of fuzzy singular signal is researched theoretically. It is proved that wavelet’s detection for a fuzzy singular signal corresponds to that a new wavelet is used to detect an ideal singular signal. The generating definition of this kind of new wavelet and its example are given, the example of simulation of ideal singular signal’s being fuzzed and wavelet’s detection for this fuzzy singularity are given, the singularity detecting process for a fuzzy singular signal in engineering practice is also given. All these results back up the theoretical analysis.

In this paper,an efficient and robust ΣΔ-STAP algorithm for moving targets detection in nonhomo- geneous environment is investigated,which is implemented based on Multistage Wiener Filter(MWF).For culling the training data,a two stages hybrid nohomogeneous detection algorithm is proposed.Based on the general sidelobe canceller structure of MWF,the training data can be firstly censored by the mainbeam output and then followed by the Adaptive Power Residual(APR)detection.In addition,the modified Concurrent Block Processing(CBP) is introduced into the ΣΔ-STAP algorithm, which can significantly reduce the computational load. Theoretical analysis and simulation results are presented to demonstrate that, the aforementioned approach can effectively detect the outliers and improve the targets detection performance. This approach has the advantage of fast convergence, low computation load, and good robustness, which is feasible for engineering application.

Since there is high difference between the velocities of platforms, the spatial synchronization of the antenna footprints is a big methodical and technological challenge for spaceborne/airborne hybrid bi-static SAR. Based on the method presented in the published literatures, a mathematical model for antenna steering is established and a set of concerned formulae is derived aiming to accommodate the ellipsoidal trajectory of satellites, the ellipsoidal shape of the earth and non-parallel trajectories between the platforms. The practicability of the proposed method is verified by the result of the simulation, which shows that it can achieve useful scene extension in azimuth with an adequate resolution in azimuth.

This paper concerns the issue of signal characteristic of side-looking SAR during its diving flight. The geometric and target range expression are built and Doppler parameter variation with operation time is analysed. The corresponding azimuth match filtering function and phase error correction factor based on Doppler parameter are provided for motion compensation. The validity and feasibility of the method is demonstrated by the simulation.

Wavenumber Domain Algorithm (WDA), as a superior SAR signal processing algorithm, is widely applied to the case of wide aperture and high squint angle. However, Interpolation in the 2-dimensional frequency domain is necessary and the motion compensation can not be integrated, so it can not be implemented easily in the real-time processing. In this paper, two modified version of WDA are exploited: one is fit for low-accurate processing, in which the residual Range Cell Migration (RCM) is ignored to improve the processing efficiency; Another is fit the high-accurate processing, in which the FRactional Fourier Transform (FRFT) is employed to correct residual RCM. The two algorithms are free of interpolation and able to be implemented in the real-time processing. In addition, the phase errors of the two algorithms are analyzed particularly. Finally, the results of simulating the point targets and processing the real X-band data are given. The results show that the two algorithms can satisfy the requirements of the real engineering.

In order to improve the precision of phase unwrapping in InSAR data processing, a new method is presented based on iterative-weighted greedy algorithm. First, the theory derivation is given in detail. Second, to make the result jump out the local optimization and approach the true phase, an iterative-weigthed greedy algorithm is addressed. Finally, the experiment analysis on simulation data and the real InSAR data verifies the effectiveness of the novel method.

The development of Doppler parameter estimating algorithm of bistatic SAR is a pivotal issue, which is still in progress and not sufficiently solved. This paper describes firstly the special case of equal velocity vectors and parallel flight paths of transmitter and receiver, and then makes detailed and mathematical study on the character of Doppler parameter under the above bistatic SAR configuration. Based on the above analysis, this paper provides a new Doppler parameter estimating algorithm of bistatic SAR by Radon transform, which can gets accurate Doppler center and Doppler rate. As a result, it is a feasible Doppler parameter estimating algorithm of bistatic SAR, of which the validity is also proved by the simulation of computer in the last.

DEM reconstruction is a step in data processing of spaceborne InSAR, its error is influenced by baseline error and GCP, etc. In this paper, DEM reconstruction method using GCP based on classic one was presented. To the reconstruction methods, the tranferring relationship between reconstruction error and baseline error was analyzed. The relationship shows that the requirement on orbit measuring precision is exigent, but when using GCP, in the situation of the same orbit measuring precision, the reconstruction error is reduced. In order to reduce the requirement on orbit measuring precision and at the same time to keep reconstruction precision, GCP should be used. In addition , the transferring relationship can direct designing some parameters of the system.

Ultra-WideBand (UWB) through-wall imaging radar is a promising technique and can be widely used for detecting and locating moving people through obstacles. In this paper, time domain beamforming method is presented for UWB through-wall imaging applications. The propagating wave slows down, encounters refraction and is attenuated as it passes through the wall. Firstly, the travel time is calculated from the antenna to the target in closed form based on the refraction model. Next, the beamformer design is presented, which incorporates the wall effects. Finally, Finite-Difference Time-Domain is used to demonstrate the efficacy of beamforming method and the impact of incorrect estimates of the wall thickness and dielectric constant on performance is also considered.

A baseline design method is proposed for the spaceborne small satellites formation INterferometric Synthentic Aperture Radar (INSAR). This technique is based on the space geometry of the small satellites formation and the real geographic model. An analysis is given to the characteristic of the interferometric echoes, the method of choosing the critical and optimal baseline is also presented. The effect of the equivalent number of looks, signal to noise ratio and the topographic slope is also analyzed. Simulation design is carried out according to the C-band small satellites formation, in one orbit period, the variation of interferometric baseline and the elevation precision are presented. The simulation results validate the effectiveness of this baseline design method.

Frequency modulation and amplitude compensation of interruptedly received LFM signals are studied to precede a false target group based on interrupted T/R jamming system. The distribution of a false target group can be controlled by frequency modulation with received signal based on group delay of matched filter for LFM waveform. Amplitude loss caused from frequency mismatch and interrupted receiving is compensated respectively, so that the false target group can suppress the true target on amplitude to make effective jamming against radar. Finally, numerical simulations verify the analysis.

Multiple Descriptions (MD) speech coder can provide robust speech communication over unreliable channels such as the internet. However, existing MD speech coders use fixed scheme for different packet-loss environments. A novel Adaptive Multiple Descriptions Sinusoidal Coder (AMDSC) is proposed, which can vary in coding multiple descriptions according to the network packet-loss rate with optimally adding redundancy between two descriptions in order to make the final distortion minimum. Simulation results show that the proposed AMDSC outperforms existing MD speech coders by taking network loss characteristics into account.

This paper proposes a novel method which uses spectral stability as feature parameter to discriminate speech and laugh. It is found that the spectral stability of speech is obviously smaller than that of laugh, which indicates that the spectral stability can be used as a feature parameter to discriminate speech and laugh. The performance of discriminating speech and laugh by using Spectral Stability (SS), Mel-Frequency Cepstrum Coefficients (MFCC), Perceptual Linear Prediction (PLP) and pitch, are compared to each other in the same experiment conditions. The experiment results show that the accuracy are respectively 90.74% and 73.63% by using spectral stability as feature parameter to discriminate speech and laugh in the speaker-dependent and speaker-independent conditions, and the discrimination power of spectral stability is superior to the counterparts of other feature parameters.

Incorporating masking properties of the human auditory system in wavelet domain, this paper proposed a new algorithm of wavelet package speech enhancement based on the time-frequency threshold. New algorithm first obtains speech pre-estimation by frequency-based de-noising method, then, via tracing the variation of time-frequency information of the speech pre-estimation, the threshold is modulated adaptively. Finally, the noisy speech is de-noised by means of time-frequency thresholding the coefficients of the wavelet package. With comparing to the traditional wavelet algorithms, the proposed algorithm offers more pleasant enhanced speech with less distortion and residual noise in the additive Gaussian noise environments, and the experimental results demonstrate its better performance in Subjective test, input and output SNR test, and Modified Bark Spectral Distortion (MBSD) measurement tests.

Based on the concept of immunodominance,antibody clonal selection theory and quantum bit strategy, a Quantum-inspired Immune Clonal Multiobjective Optimization Algorithm(QICMOA)is proposed.The QICMOA is compared with RWGA,SPEA and MISA in solving low-dimensional problems.The statistical results show that QICMOA has a good performance in converging to true Pareto-optimal fronts with a good distribution.

Fuzzy-rough attribute reduction is one of the important topics in the research on fuzzy-rough set theory. In this paper,the information entropy is generalized in rough set so that it could be used to value the importance of attribute under fuzzy circumstance.A new heuristic algorithm based on mutual information for fuzzy-rough attribute reduction is introduced and illustrated with a simple example.

Text data presented in images and video contains useful and important semantic information for semantic-based image retrieval system. In this paper, a method is proposed for text detection based on fuzzy logic and homogeneity. First, the original images is fuzzified based on the maximum entropy principle. Then edge and textural information is extracted to evaluate the homogeneity of image which is transformed to fuzzy homogeneity domain. Finally text region is confirmed with texture analysis in fuzzy homogeneity domain. Experimental results confirm that the proposed method achieves better performance in complex background and is applicable to various kinds of video and images.

Conventional polarization diversity suffers from a strong imbalance between the average powers received on its two diversity branches. A novel method is proposed to tackle this problem by pre-combining of the two diversity branches before diversity combining process. Equal average received branch powers thus can be obtained. Theoretical analysis as well as physical interpretation is presented. Numerical examples under typical channel model show that the proposed method can be used to improve the diversity performance significantly, especially in the high Cross Polarization Discrimination (XPD) environments.

This paper proposes a class of Quasi-Cyclic Low-Density Parity-Check (QC-LDPC) codes with high code rates, which is an efficient encoding algorithm due to the almost lower triangular form and simple structure of their parity-check matrices. Since the parity-check matrix of the QC-LDPC code is composed of blocks of circulant matrices, the required memory for storing it can be significantly reduced, compared with randomly constructed LDPC codes. Based on the quasi-cyclic structure of the parity-check matrix, a new approach is proposed to analyze the distribution of the short length cycles of their bipartite graph, and a corresponding construction method of QC-LDPC codes without cycles of length 4 is presented. Simulation results show that the proposed codes not only have low encoding complexity and low error floor but also perform well with iterative decoding.

Distributed linear dispersion codes are proposed for the space time coding in wireless network where cooperative nodes can not be decided priori.The nodes in cooperation are coded with different dispersion vectors. The mutual information loss when the number of cooperative nodes decreased is conducted and a coding criterion of distributed dispersion codes is developed accordingly.The simulation results show that the distributed dispersion codes with the coding criterion achieve good performance.

Let R=F_q+uF_q+…+u^k-1F_q,G=R[x]/ and λ be an invertible element in R.A new Gray mapφfrom Gⁿ to R^tn is defined.It is proved that J is a linear x-constacyclic code of length n if and only if φ(J) is a linearα-constacyclic code over R of length tn.By means of the theory of finite rings the structure and sizes of all(uλ-1)-constacyclic codes over R of length p^e are obtained.Especially,the structure and sizes of the duals of all (uλ-1)-constacyclic codes of length 2^e over the ring F_2^m+uF_2^m are also obtained. Some of the results about repeated-root negacyclic codes over the ring Z_2^a are generalized.

Based on analysis of some characters of the families of Bent Complementary Function Pairs(BCFPF), the equivalence relations of BCFPF with the families of Hadamard complementary matrix pairs is studied.The equivalence relation is the necessary and sufficient condition for constructions of BCFPF。A sort of construction method of BCFPF is provided.The families of Hadamard complementary matrix pairs and can be constructed correspondingly by using the equivalent relationships.

Considering high complexity of multiple reference frames in Multi-view Video Compression (MVC), a fast coding algorithm for MVC is presented based on the traits of multi-view video. The propose algorithm improves the design of reference-lists in H.264 standard that adapts to traditional video coding, and adjusts the old reference-lists using the temporal and spatial correlations of multi-view video. Additionally, the strategy of mode pre-decision is also used to reduce the computational complexity. The experimental results show that the proposed method can reduce encoding complexity and speed up encoding process effectively. Though the new algorithm is implemented on M-Picture prediction structure, it can be also used in other multi-view video coding structures with multiple reference B-frames.

Based on indoor RSS distance-loss model,an indoor localization system is set up with means of area partition.Parameters of the model are set by comparing the signal data recorded at several collection spots with the ideal signal value lists generated by the computer,which simulates the actual environment.Then users’ location estimates can be achieved with Maximum Likelihood(ML)estimation algorithm.Experiments show the algorithm is effective and can obtain quite precise location result.

A low cost, real-time CSI feedback method is proposed. The analog DownLink Channel State Information (DL-CSI) obtained at receivers is spreaded and then superimposed upon UpLink User Sequences (UL-US) before transmitting, thus avoiding DL-CSI from exclusive occupation of system resources. Using interference cancellation, iterative UL-US detection and DL-CSI estimation is carried out at base station. Due to spreading, DL-CSI can be accurately recovered even with little allocated energy. Simulations results demonstrate the practicability of the proposed method.

To overcome the drawbacks of samples impoverishment, an evolutionary particle filtering algorithm is proposed for blind signal detection over flat Rayleigh fading channels whose model coefficients are unknown. During the resampling of particle filtering, evolutionary programming is used. The evolutionary particle filtering algorithm is adopted to overcome the drawbacks of samples, which forms into a blind detection based in evolutionary particle filtering. It is shown through simulations that the proposed particle filtering detector maintains comparable performance with mixture Kalman filter with known model coefficients.

In this paper, a multiuser detection algorithm (named MMSE-EOPPIC) combined MMSE frequency domain equalization (MMSE-FDE) with Partial Parallel Interference Cancellation based on Energy-Ordering (EOPPIC) is proposed for DS-CDMA system over frequency-selective channels. MMSE-FDE based on overlap-cut method instead of Rake receiver is firstly used to initially estimate all users’ data information, and then partial interference cancellation is in turn implemented for each user in descending order of estimated energy at each iterative stage. In order to improve the detection reliability of each iterative stage, the stronger users’ current stage hard decisions are used to regenerate the weaker users’ multiple access interference (MAI). Simulation results show that MMSE-EOPPIC can efficiently improve the Bit Error Rate (BER) performance of system.

An algorithm is presented for dynamic location in distributed mobile communication system. In the algorithm, Doppler frequency offsets of the MS are estimated by RAUs firstly, and the velocity in each direction from the MS to each RAU is derived. And then, the states equation and the observation equation are constituted, and an Extended Kalman Filter (EKF) is employed to estimate the position of the MS, and the trajectory of the MS can be obtained through a step by step way. The algorithm can improve the location precision because of employing of Kalman filter, which reduces the error accumulation in the Doppler dynamic location algorithm, and this issue is verified by simulation as well.

The Non-Line-Of-Sight (NLOS) error is the main difficulty for mobile user location in cellular wireless communication system. An accurate and unbiased estimation approach using Probability Density Function (PDF) estimator and biased Kalman filter is presented to mitigate the NLOS error in this paper. The simulation results indicate that with the less prior information about communication environments, the approach has a better location performance even in severe NLOS situations.

The multiuser scheduling issue in Spatial Division Multiplexing/Orthogonal Frequency Division Multiple Access (SDM/OFDMA) wireless communication system is studied. This issue is characterized as three dimensions of time, frequency, and space. A utility based multiuser scheduling algorithms is proposed to both improve the system resource utilization and maximize the user’s utility. The computer simulation results show that the performance of the proposed algorithms is similar to the exhaustive searching algorithm while the complexity is highly reduced.

This paper introduces the operating fundament of Cognitive Ultra WideBand (CUWB) wireless communication system and gives a scheme of dynamically obtaining adaptive emission mask based on spectrum sensing to adapt to spectrum environment and be compatible with FCC spectral mask. Then, a method to generate adaptive CUWB shaping pulse is proposed based on weight combination of Prolate Spheroidal Wave Functions(PSWFs) matching UWB multiple sub-band spectral mask. The simulation results show that the pulse waveforms shaped by this method conform the spectral mask constraint for CUWB, adapt to dynamical variety of the spectral mask.

In this paper, the situation optimization issue of a CDMA Bunched system is investigated and a method that optimize the points distribution is given. According to outage equation of CDMA system, a coverage control algorithm is proposed based on gradient descent algorithm. Computer simulation results show that outage probability of the optimized system is one order of magnitude less than the uniform distributed system and 40% less than the regular distributed system..

The relation between the Cartesian product and authentication codes is studied in this paper. A new idea to use the private keys to carry the information of the authentication symbols is presented, which is based on the character of Cartesian product’ structure. And the Cartesian product–based optimal authentication codes with equal cheating probabilities of all orders are constructed, which can be easily designed and can be applied well to engineering. In this paper, the secret authentication codes with equal cheating probabilities of all orders are also constructed which are founded on Cartesian product and Latin square. The two construction methods mentioned above need no pre-storing encoder matrix, so that a mass of storage is saved. At the same time, the two schemes can offer an enough security level expected.

Macrocosm approximation is a class of attacks to ciphers by replacing a strong cipher function with a weak cipher function.The XOR of the two functions is called the noise function of this macrocosm approximation. This paper studies the probability distributions of the noise functions produced by macrocosm approximation of binary addition and triple addition modulo 2ⁿ with XOR,and gives the computation formulae of the probability distributions of the corresponding noise functions and the square sums of the probabilities, which is helpful to recognize the ability of resistance to macrocosm approximation of binary addition and triple addition modulo 2ⁿ with XOR.

Constructing provably secure cryptographic primitives under weak assumptions can improve the security of cryptographic schemes efficiently. Further research on the construction of public-key cryptosystem is provided, and a new public-key encryption primitive is investigated. This scheme is more efficient than that of existing LUC cryptosystems. More over, the proposed scheme is provable secure and its security is proved to be equivalent to the factorization of RSA modulus. At last, an application in signature is suggested; forgery of signature is also equivalent to the factorization of RSA modulus.

In this paper,the security of RSA system is studied if the private keys p and q share their least significant bits.The result shows that RSA system is more vulnerable in this condition when the private key d is small.So it should be careful to void this kind of weak key.

Based on a public-key encryption algorithm with “multiple decryption keys mapping to one encryption key” , a group re-keying protocol is proposed and then combining the protocol with the LKH algorithm a two-level decentralized group key management scheme is designed for Source Specific Multicast(SSM). Its backward secrecy, forward secrecy and non-collusion with high probability are demonstrated. The performance bottleneck of sub-group managers and the “1-affects-n” problem existing universally in the common group key approach are miti-gated through the long-livedness of private keys in the upper level and the method of key translation. The analysis shows that adopting a hybrid cryptosystem the novel scheme possesses some advantages of two distinct classes of approaches to group key management.

A new packet scheduling algorithm Modified Exponential rule(MExp)is proposed for wireless real-time multimedia applications to provide enhanced scheduling fairness.The scheduling fairness of MExp is investigated through theoretical analysis and verified by system level simulation.

There is a great demand on multimedia services in wireless networks. Capacity analysis of a multi-service CDMA communication system is employed in which the concept of equivalent bandwidth is introduced, and then an optimal Call Admission Control and Resource Allocation algorithm (CAC-RA) is proposed. in CAC-RA, multimedia traffic is classified into two classes: real-time trafficand non real-time traffic, and manage Call Admission Control (CAC), handoff scheme and resource allocation (RA) together by adopting Markov Decision Process model for adaptive real-time applications, queuing model for non real-time applications ,and nonlinear programming for the proposed revenue function which combine these two models. Numerical results reveal that the proposed CAC-RA scheme adapts itself well to multi-service CDMA networks by achieving reasonable utilization of resources.

This paper analyzes Wf-XML based interoperation mechanism between workflow management systems and the characteristics of Web Services based description methods for network management services. Making use of the description methods for network management services given by MUWS, the deficiencies of Wf-XML are improved and interoperation interfaces between network management business process management systems are defined. The implementation and application scenarios of the interoperation interfaces are also illustrated. The functionalities of the interoperation interfaces are clearly defined with good extensibilities.

This paper analyses routing and queuing performance for self-similar traffic in mobile Ad hoc network which is ubiquity but neglected. A Multi-path Backup Optimized Power (MBOP) algorithm is presented based on network programming model, which exerts multi-path backup routing and optimizes the total transmission power. This algorithm is suitable for structure-changed mobile Ad Hoc network. The simulation result shows that the new algorithm can increase the throughput of network and improve delay.

Trust relationship between participants is indispensable to set up in a large-scale distributed P2P file-sharing system. A novel trust model for P2P system based on advanced D-S theory of evidence is proposed in this paper to solve this problem, in which mathematic analysis and some measures are presented to defense against several malicious attacks. The experimental results show that, compared to the current some trust models, the proposed model is more robust on trust security problems and more advanced in successful transaction rate.

Based on analyses of CAN(Content-Addressable Network) protocol, DFO (Distributed Fairly Optimal) arithmetic is proposed, which use peer’s up/down bandwidth usage and overlay multicast link efficiency defined by utility function as standard. DFO define request/response utility function respective and evaluate global transmit overload based on peer input efficiency vector to conform a fire restrict. DFO can reduce average query latency and global bandwidth cost by optimizing global utility. Simulative results and analysis has shown that DFO improved on hot spot problem in CAN, can achieve the purpose of minimum global query latency and maximal transmit overload balance.

Topology control in a wireless sensor network balances load on sensor nodes and increases network scalability and lifetime. Clustering architecture is one of the effective approach. In this paper, we proposed a distributed clustering algorithm MWBC for maximal-lifetime wireless sensor network design, which take into consideration many factors such as the ideal degree, current energy, transmission power, link quality, and relatively position of nodes. Through simulations we have compared the performance of proposed algorithm with that of the LEACH and HEED algorithms in terms of the number of clusters formed, and the Load Balance Factor(LBF)value. The results demonstrate the superior performance of the proposed algorithm.

DoS (Denial of Service) attacks have become one of the most severe security threats to the global Internet increasingly. It makes the resources of Internet used up and incurs congestion by sending a large number of packages constantly. This paper proposes using signal processing method to analyze DoS attacks. Because of sending mass packages, it must have much more power. For this, the FIR filter is designed to filtering the illegitimate frequencies in frequency domain and the LAR (Legitimate traffic to Attacked traffic Ratio) is improved. Then much more resources and service can be supplied for the users.

A fast computation method of mutual coupling inverse matrix in uniform linear antenna array based on RBF neural network is proposed to solve the problems of computational complexity and difficult to implement in real-time in traditional method. Different training methods can be applied according to different calculation methods for mutual coupling inverse matrix. The mutual coupling inverse matrix can be estimated in real-time owing to the RBFNNs’ superior ability of parallel processing, and the computation problem can be transformed to nonlinear function approximation. The specific steps are presented. And the simulation results prove its superiority to other methods.

This paper focuses on a special kind of three-plate cavity reflectors which is useful in EM backscattering model of large complex targets over land or sea surface. After employing Computer Graphics (CG) method to eliminate shadowing effect, Physical Optics (PO) and Area Projection (AP) method are combined to analyze specular reflection and multiple scattering mechanism to calculate the Radar Cross Section (RCS) of different reflectors. Finally, by combining with sea reflection coefficient under different sea states, a procdure is proposed to compute the RCS of simplified ship targets over sea surface. The results show that multiple scattering can form obvious RCS characterization under certain conditions.

The W-band high-power CW gyrotron oscillator has an important application in the field such as millimeter-wave non-lethal weapon etc.In this paper,the operating mode of the gyrotron is chosen by the calculation of starting current,and the 94GHz CW gyrotron oscillator circuit is optimally designed using a self-consistent nonlinear calculating code GYROSC developed by authors.The result shows that the designed W-band CW gyrotron oscillator can obtain output power 40kW,and electron efficiency more than 30%.

A single-anode electron gun is designed and simulated according to the requirements of the gyrotron traveling wave amplifier. Firstly，the initial parameters for example the cathode angle, the cathode emitter strip and the distance between cathode and mod-anode are designed based on analytic trade-off equations. Secondly，the final beam parameters are determined with the electron trajectory code EGUN. The results reveal that when the accelerated voltage is 70kV and the beam current is 4.55A, electron gun has the axial velocity spread of 2.4%, and the ratio of the transverse velocity to the axial velocity is equal to 1.0, which can satisfy the requirement of the low electron beam velocity spread in the gyrotron traveling wave amplifier.

A novel CMOS bandgap reference is presented.A negative feedback clamp technique is used which eliminates the offset of Op-Amps and simplifies the design.A regulated cascode configuration is used to improve Power Supply Rejection Ratio(PSRR).It is implemented in SMIC standard 0.18μm CMOS process,the results from HSPICE simulation show that the temperature coefficient between-15～70℃ is 10.8ppm/℃,and the PSRR at 10Hz is 74.7dB,the output noise voltage is 148.7μV/sqrt(Hz).

Output circuit of multi-beam klystron, which is consist of coaxial cavity with high-order mode of TM₃₁₀ and coupling of waveguide hole, is analyzed in this article. Some methods and steps of adjusting external Q-factor of cavity are described in theory. Some simulations are also made using CST MicroWave Studio (MWS). Output cavity with symmetrical field distribution of TM₃₁₀ mode and low external Q-factor is obtained in this article.

Wireless Multimedia Sensor Networks (WMSNs), developed from traditional Wireless Sensor Networks(WSNs), is a novel sensor network integrating sensation functions of multimedia streaming (e.g. audio, video, image) and has wide applications. In this paper, the concept and the characteristics of WMSNs are described by comparing with traditional WSNs. Then, on the basis of a survey of the current research status, the key techniques of WMSNs, including node systems, MAC protocols, routing protocols, multimedia signal processing, are discussed in detail. Finally, the current problems are demonstrated, and the further research issues are also discussed.