基于信元离开间隔与令牌控制的成形算法

提出基于信元离开间隔与令牌控制的成形算法，该算法可使源流量的峰值速率、平均速率、最大突发长度和ＣＤＶ变更到期望的值，并可保证已成形流量的透明性．而且当源流量符合声明的参数时，成形延迟很小．通过仿真，评估了所述成形算法的性能．给出了基于共享缓冲区、链表和递减排序器的成形器实现结构，并对其操作进行了研究．

两级CDV容限参数的流量强制与成形算法

信元时延变化ＣＤＶ对峰值速率警管有很大影响，文中首先提出基于通用信元速率算法ＧＣＲＡ（Ｔ，δ）的ＣＤＶ成形算法，该算法能有效地成形ＣＤＶ使之符合ＧＣＲＡ（Ｔ，δ）算法对ＣＤＶ容限的要求；在对ＣＤＶ成形算法分析的基础上，进一步提出了两级ＣＤＶ容限参数的流量强制与成形算法ＴＰ－ＥＳＡ，ＴＰ－ＥＳＡ既能成形ＣＤＶ到任意预设的值，又能防止连接对流量的恶意滥用。文中对算法的实现和操作也进行了研究。

基于GCRA(T,δ)的CDV成形算法及其实现

文章提出基于通用信元速率算法GCRA（T，δ）的CDV成形算法，该算法能有效地成形CDV使之符合GCRA（T，δ）算法对CDV容限的要求，并对CDV成形器的实现和操作进行了讨论。

利用改进扫描线法的面曝光快速成形的掩模图形

在对掩模图形的生成机理进行研究的基础上,提出用扫描线法生成基于STL数据模型的掩模.针对大数据量的轮廓边扫描效率较低的问题,改进传统的扫描算法:重新定义边数据结构,将边表分为3个动态区间以存储相应的边,从而实现了在无需判断截面曝光域与非曝光的情况下,直接借助边表填充截面轮廓,快速生成具有多层嵌套关系的排模图形.该方法可避免构建与维护活动边表,简化扫描线算法的实现过程,同时可解决传统算法较难解决的奇点问题.

Evaluation of volcanic reservoirs with the "QAPM mineral model" using a genetic algorithm

Gas-bearing volcanic reservoirs have been found in the deep Songliao Basin, China. Choosing proper interpretation parameters for log evaluation is difficult due to complicated mineral compositions and variable mineral contents. Based on the QAPF classification scheme given by IUGS, we propose a method to determine the mineral contents of volcanic rocks using log data and a genetic algorithm. According to the QAPF scheme, minerals in volcanic rocks are divided into five groups： Q（quartz）, A （Alkaline feldspar）, P （plagioclase）, M （mafic） and F （feldspathoid）. We propose a model called QAPM including porosity for the volumetric analysis of reservoirs. The log response equations for density, apparent neutron porosity, transit time, gamma ray and volume photoelectrical cross section index were first established with the mineral parameters obtained from the Schlumberger handbook of log mineral parameters. Then the volumes of the four minerals in the matrix were calculated using the genetic algorithm （GA）. The calculated porosity, based on the interpretation parameters, can be compared with core porosity, and the rock names given in the paper based on QAPF classification according to the four mineral contents are compatible with those from the chemical analysis of the core samples.

Energy-Efficient Transceiver Design for Multi-Pair Two-Way Relay Systems

In this paper, we focus on energy-efficient transceiver and relay beamforming design for multi-pair two-way relay system. The multi-antenna users and the multi-antenna relay are considered in this work. Different from the existing works, the proposed algorithm is energy-efficient which is more applicable to the future green network. It considers both the sum-MSE problem and the power consumption problem for the users under the relay power constraint. Based on the optimal condition decomposition(OCD) method, the energy-efficient precoders at the users can be designed separately with limited information exchanged. The proposed relay beamforming algorithm is based on the alternative direction method of multipliers(ADMM) which has simpler iterative solution and enjoys good convergence. Simulation results demonstrate the performance of the proposed algorithms in terms of power consumption and MSE performance.

A unified constitutive model for multiphase precipitation and multi-stage creep ageing behavior of Al−Li−S4 alloy

A unified constitutive model is presented to predict the recently observed“multi-stage”creep behavior of Al−Li−S4 alloy.The corresponding microstructural variables related to the yield strength and creep deformation of the alloy during the creep ageing process,including dislocations and multiple precipitates,have been characterized in detail by X-ray diffraction(XRD)and transmission electron microscopy(TEM).For the yield strength,the model considers the multiphase strengthening behavior of the alloy based on strengthening mechanisms,which includes shearable T1 precipitate strengthening,non-shearable T1 precipitate strengthening andθ′precipitate strengthening.Based on creep deformation mechanism,the“multi-stage”creep behavior of the alloy is predicted by introducing the effects of interacting microstructural variables,including the radius of multiple precipitates,dislocation density and solute concentration,into the creep stress−strain model.It is concluded that the results calculated by the model are in a good agreement with the experimental data,which validates the proposed model.

A NOVEL SUPER-RESOLUTION BEAMFORMING ALGORITHM

A novel simply-structured hybrid smart antenna system suitable to be used in ad-hoc network terminals is proposed in this letter. The super-resolution beamforming algorithm is also pre-sented based on the system using DOA estimation results. The algorithm can switch the beamforming to the direction of the expected signal and get the best transmitting performance after the pre-beamforming of the Butler matrix. The shifting value formulas are presented to obtain the best SNR when there is no interfering signal and to acquire the highest Signal to Interference Ratio (SIR) as there is one interfering signal. When there are more than one interfering signals,the pre-beamforming feature of the Butler matrix can also suppress the interfering signals. Simulation results verified the algorithm.

Method of closed loop springback compensation for incremental sheet forming process

The closed loop control model was built up for compensating the springback and enhancing the work piece precision.A coupled closed loop algorithm and a finite element method were developed to simulate and correct the springback of incremental sheet forming.A three-dimensional finite element model was established for simulation of springback in incremental sheet forming process.The closed loop algorithm of trajectory profile for the incremental sheet forming based on the wavelet transform combined with fast Fourier transform was constructed.The profile of processing tool path of shallow dishing with spherical surface was designed on the basis of the profile correction algorithm.The result shows that the algorithm can predict an ideal profile of processing track,and the springback error of incremental sheet forming is eliminated effectively.It has good convergence efficiency,and can improve the workpiece dimensional accuracy greatly.

A Semi-blind Adaptive Beamforming Algorithm for Wideband Coherent CDMA

This paper presented a novel semi blind adaptive beamforming algorithm specially designed for wideband coherent CDMA mobile communication systems with multiplexd control and data channels. The presented algorithm uses a parallel structure to exploit not only the desired user’s pseudo noise sequence but also the information from multiplexed pilot and data symbols, thus help achieve faster convergence and lower bit error rate. Monte Carlo simulation results verified the performance improvement in terms of BER.

Cyclic beamforming using fractional Fourier transform domain cyclostationarity

A minimum mean-squared error （MSE） beamforming algorithm employing the optimum fractional Fourier transform （Opt-FrFT） domain second-order cyclostationarity is proposed. This method can efficiently filter out the compact desired chirp signal, with a consequence that the cyclically uncorrelated interferences and stationary （colored） Gaussian noise are greatly suppressed in the Opt- FrFT domain. This improves the MSE minimization cyclic beamformer by reducing effectively the Opt-FrFY domain signal-noise cross terms in the presence of finite data length de-correlation operation. Simulation results show that the new method works well under a wide range of signal-to-noise ratio （SNR） and signal-to-interference ratio （SIR）.

Multi-objective optimization of stamping forming process of head using Pareto-based genetic algorithm

To obtain the optimal process parameters of stamping forming, finite element analysis and optimization technique were integrated via transforming multi-objective issue into a single-objective issue. A Pareto-based genetic algorithm was applied to optimizing the head stamping forming process. In the proposed optimal model, fracture, wrinkle and thickness varying are a function of several factors, such as fillet radius, draw-bead position, blank size and blank-holding force. Hence, it is necessary to investigate the relationship between the objective functions and the variables in order to make objective functions varying minimized simultaneously. Firstly, the central composite experimental(CCD) with four factors and five levels was applied, and the experimental data based on the central composite experimental were acquired. Then, the response surface model(RSM) was set up and the results of the analysis of variance(ANOVA) show that it is reliable to predict the fracture, wrinkle and thickness varying functions by the response surface model. Finally, a Pareto-based genetic algorithm was used to find out a set of Pareto front, which makes fracture, wrinkle and thickness varying minimized integrally. A head stamping case indicates that the present method has higher precision and practicability compared with the "trial and error" procedure.

Integrated optimal method for cell formation and layout problems based on hybrid SA algorithm with fuzzy simulation

To adapt to the complex and changeable market environment,the cell formation problems(CFPs) and the cell layout problems(CLPs) with fuzzy demands were optimized simultaneously. Firstly,CFPs and CLPs were described formally. To deal with the uncertainty fuzzy parameters brought,a chance constraint was introduced. A mathematical model was established with an objective function of minimizing intra-cell and inter-cell material handling cost. As the chance constraint of this problem could not be converted into its crisp equivalent,a hybrid simulated annealing(HSA) based on fuzzy simulation was put forward. Finally,simulation experiments were conducted under different confidence levels. Results indicated that the proposed hybrid algorithm was feasible and effective.

Formation control for networked spacecraft in deep space

In this paper, two formation controllers are developed under directed and undirected communication topology for six-degree-of-freedom （6-DOF） networked spacecraft flying in deep space. In the control algorithm, any explicit leader does not exist in the formation team and the proposed controller is required that each spacecraft communicates with its neighbors only, which avoids having to communicate each spacecraft＇s trajectory and therefore reduces the required communication loads of the whole formation. The proposed control strategy allows that each spacecraft can track its desired position and attitude and simultaneously the whole group moves to the desired formation and obtains its desired relative attitudes between spaceerafts. Simulation results demonstrate the effectiveness of the proposed controller.

Single-Frequency Matching Pursuits Based Time-of-Flight Measurement in Viscoacoustic Medium

Broadband ultrasound signals will produce distortion in viscoacoustic medium, which may influence the accuracy of time-of-flight (TOF) measurement. Under the condition of single-frequency acoustic source, the wave propagation process in viscoacoustic medium was analyzed and an approximate solution of the wave propagation was given. Instances of broadband ultrasound were analyzed and simulated based on the single-frequency results. A single-frequency matching pursuits (SFMP) algorithm was then introduced to solve the waveform distortion problem. Time-frequency decomposition was applied to extracting the single-frequency compositions from broadband ultrasound signals, and then these compositions were sent to the matching pursuits (MP) algorithm for calculating the TOF parameters. Compared with the broadband signals, the shapes of extracted single-frequency signals change more slightly as distance and attenuation coefficient increase. The residuals of SFMP were far less than those of MP algorithm. Experimental results show that the SFMP algorithm is able to eliminate waveform distortion of broadband ultrasound in viscoacoustic medium, which helps improve the accuracy of TOF measurement.

New Diamond Block Based Gradient Descent Search Algorithm for Motion Estimation in the MPEG- 4 Encoder

Motion estimation is an important part of the MPEG- 4 encoder, due to its significant impact on the bit rate and the output quality of the encoder sequence. Unfortunately this feature takes a significant part of the encoding time especially when the straightforward full search(FS) algorithm is used. In this paper, a new algorithm named diamond block based gradient descent search (DBBGDS) algorithm, which is significantly faster than FS and gives similar quality of the output sequence, is proposed. At the same time, some other algorithms, such as three step search (TSS), improved three step search (ITSS), new three step search (NTSS), four step search (4SS), cellular search (CS) , diamond search (DS) and block based gradient descent search (BBGDS), are adopted and compared with DBBGDS. As the experimental results show, DBBGDS has its own advantages. Although DS has been adopted by the MPEG- 4 VM, its output sequence quality is worse than that of the proposed algorithm while its complexity is similar to the proposed one. Compared with BBGDS, the proposed algorithm can achieve a better output quality.

电波传播与天线

Y99-61507-1665 9915244盲自适应波束成形起始方法的比较=A comparison ofinitialization schemes for blind adaptive beamforming[会,英]/Biedka,T.//1998 IEEE International Conferenceon Acoustics.Speech and Signal Processing,Vol.3 of 6:Digital Signal Processing.—1665～1668(HG)许多盲自适应波束成形算法要求选择一个或更多个非零起始加权矢量。文中比较了三种可选择起始方法,这些方法仅依赖于观察数据的2阶统计性,基于观察数据协方差矩阵的 Gram-Schmidt 的正交化、本征合成以及 QR 分解。通过计算机模拟说明本征合成方法能获得很好性能。

Adaptive robust beamformer for multi-pair two-way relay networks with imperfect channel state information

In wideband multi-pair two-way relay networks, the performance of beamforming at a relay station(RS) is intimately related to the accuracy of the channel state information(CSI) available. The accuracy of CSI is determined by Doppler spread, delay between beamforming and channel estimation, and density of pilot symbols,including transmit power of pilot symbols. The coefficient of the Gaussian-Markov CSI error model is modeled as a function of CSI delay, Doppler spread, and signal-to-noise ratio, and can be estimated in real time. In accordance with the real-time estimated coefficients of the error model, an adaptive robust maximum signal-to-interferenceand-noise ratio(Max-SINR) plus maximum signal-to-leakage-and-noise ratio(Max-SLNR) beamformer at an RS is proposed to track the variation of the CSI error. From simulation results and analysis, it is shown that: compared to existing non-adaptive beamformers, the proposed adaptive beamformer is more robust and performs much better in the sense of bit error rate(BER); with increase in the density of transmit pilot symbols, its BER and sum-rate performances tend to those of the beamformer of Max-SINR plus Max-SLNR with ideal CSI.

Graph and Hint Based Algorithm for Machining Feature Automation Recognition and Mapping

Feature recognition is a process of extracting machining features which has engineering meaning from solid model, and it is a key technology of CAD/CAPP/CAM integration. This paper presents an effective and efficient methodology of recognizing machining feature. In this approach, features are classified into two categories： pocket feature and predefined feature. Different feature type adopts its special hint and heuristic rule, and is helpful to recognize intersection feature. Feature classification optimizes search algorithm and shortens search scope dramatically. Meanwhile, extension and split algorithm is used to handle intersecting feature. Moreover, feature mapping based on machining knowledge is introduced to support downstream application better. Finally, case studies with complex intersecting features prove that the developed approach has stronger recognizing ability.