复杂涂敷目标的RCS计算

给出了一种快速计算复杂涂敷目标散射场的方法。将复杂目标电磁散射分成面元和边缘散射,运用物理光学(PO)、阻抗边界条件(IBC)、等效电流(EM C)和物理绕射理论(PTD)对复杂目标雷达散射截面(RCS)进行计算,并将计算结果与文献结果及无涂敷纯金属目标的RCS进行对比分析,结果与文献及预期估计情况吻合较好,表明该方法不仅计算简单,而且结果也较为精确。     

EM Scattering from conducting flat plates coated with thin RAM

According to the equivalence principles, high frequency approximation and boundary conditions, a method has been developed to deal with the EM scattering by a rectangular conducting flat plate coated with uniaxial anisotropic radar absorbing material (RAM). The simple and effective method is available to the system of RCS prediction in which the large complex targets modeled by facets and wedges. Numerical results show some properties of EM scattering by conducting plate coated with thin uniaxial anisotropic RAM. Biography: Yang He-lin (1984-), male, Ph. D. candidate, research direction, electromagnetic theory.     

A study on radar cross section of the two-dimensionally fractal rough surface

The analysis of the RCS from the rough sea and ground surface is made. The two-dimensionally band-limited fractal function is used to model the sea and ground surface, the scattered electromagnetic field is calculated by using Kirchhoff approximation. The validity of this result is assured by some references, which indicates that the methods are reliable. Foundation item: Supported by the National Natural Science Foundation of China(69571021) Biography: GAO Ming-qin (1974-), Master Candidate. Research field: EM scattering.     

SCTE: RCS prediction system for complex target and interaction with environment

A RCS prediction system named SCTE (Scattering from Complex Target and Environment) for calculating high-frequency electromagnetic scattering from complex target within complex environment is presented. The scattering body is described by Computer-Aided-Design (CAD) representations in which the complex body is modeled as NURBS (Non-Uniform Rational B-spline) surfaces. The complex environment (rough surface of sea or ground) is also carefully considered by using fractal function. Scattering fields are calculated by using physical optics and the equivalent currents methods. There is a good agreement between the present results and that from measurements which demonstrates the accuracy of this system. Foundation item: Supported by the National Natural Science Foundation of China Biography: CAO Qin-feng (1972-) male, Ph.D. candidate.     

Design and Implementation of Hierarchy Cache Using Pagefile

This paper presents a novel hierarchy cache architecture for the purpose of optimizing IO performance. The main idea of the hierarchy cache is to use a few megabytes of RAM and a pagefile to form a two-level cache architecture. The pagefile is equivalent to the cache disk in DCD(Disk Caching Disk). The pagefile outperforms data disks, because data are accessed in different units and different ways. Small writes are collected in the RAM cache first, and data will be transferred to the pagefile in large writes later. When the system is idle, it will destage data from the pagefile to data disks. The performance test results show that the hierarchy cache can improve IO performance dramatically for small writes, and the mail server using the hierarchy cache driver can handle transactions about 2.2 times faster than the normal mail server. The hierarchy cache is implemented as a filter driver, so it‘s transparent to the current Windows 2000/Windows XP operating system.     

Application of improved Z-buffer technique to RCS computation

This paper presents a new method for computation of the monostatic radar cross section (RCS) of electrically large conducting objects. Compared with the traditional Z-buffer technique, the improved one can record not only the illuminated surface of the body, but also the information about the shadowed part. So multi-scattering and RCS of cavity can be calculated. The second advantage of it is using dual representation, of the target's facet surface, in which the illuminated part is treated as bicubic patches for RCS calculation, and is simplified to flat facet when ray tracing is done. Excellent agreement with the experiment has been obtained. Supported by National Natural Science Foundation of China Geo Qinfeng: born in 1972, Ph. D. student     

Application of improved Z-buffer technique to RCS computation

This paper presents a new method for computation of the monostatic radar cross section (RCS) of electrically large conducting objects. Compared with the traditional Z-buffer technique, the improved one can record not only the illuminated surface of the body, but also the information about the shadowed part. So multi-scattering and RCS of cavity can be calculated. The second advantage of it is using dual representation, of the target's facet surface, in which the illuminated part is treated as bicubic patches for RCS calculation, and is simplified to flat facet when ray tracing is done. Excellent agreement with the experiment has been obtained. Supported by National Natural Science Foundation of China Geo Qinfeng: born in 1972, Ph. D. student     

Simulation of the RCS Range Resolution of Extremely Large Target

,,,.lr.0　IntroductionThe RCS(Radar Cross Section) of a target in the near zone is very important in the various civilian and militaryfields. For a complex target, we dissect it in the near zone tomany small regions and simulate the RCS of the the whole …     

Graded stable unfoldings in bifurcation problems

We introduced stability of arbitrary degree number for unfordings of bifurcation problems and established the equivalence of three stabilities. Thom's transversality theory is used to character the new stability. Foundation item: Supported by the National Natural Science Foundation of China (19871074) Biography: Zhang Guo-bin (1939-), male, Professor, research interest: singularity theory.     

外形参数对矩形截面弹体气动和隐身特性的影响

用流体动力学(CFD)数值模拟方法和图形算法(GRECO),对机载布撒器绕流场进行了数值模拟和雷达散射截面(RCS)的计算,得到气动特性数值计算结果与风洞试验结果,RCS计算结果与外场测量结果均十分吻合.在此基础上研究了矩形截面宽高比和圆角半径比对弹体气动特性和隐身特性的影响.计算结果表明,建立外形参数与气动和隐身特性关系数据库、发展基于数据库的气动特性和隐身特性的工程计算方法,是进行布撒器等非常规外形和特种部件气动设计和RCS设计的有效途径.     

The relations among various Markov chains

Some basic equations and the relations among various Markov chains are established. These works are the bases in the investigation of the theory of Markov chain in random environment. Foundation item: Supported by the National Natural Science Foundation of China (10071058-2) and Doctoral Programme Foundation of China Biography: Hu Di-he (1935-), male, Professor, research interest: stochastic processes and random fractals.     

无导电衬底单轴吸波材料的反射和透射特性

导出了无导电衬底单轴各向异性吸波材料对斜入射电磁波的反射系数和透射系数公式;分析了极化方式、入射角及材料电磁参数等对反射系数和透射系数的影响;得到关于无导电衬底单轴各向异性吸波材料对斜入射电磁波的反射和透射特性的一些重要结论．     

Real interpolation betweenB-valued martingale Hardy spaces

The interpolation spaces between Banach-space-valued martingale Hardy-spaces, between Hardy and BMO spaces are identified respectively. Some results obtained here are connected closely with the convexity and smoothness of the Banach space which the martingales take values in. Foundation item: Supported by the National Natural Science Foundation of China Biography: YU Lin (1965-), male, Ph. D. Candidate. Current research interests are in geometry of Banach spaces and Banach-spacevalued martingale theory.     

A constraction of general solution for a class of non-homogeneous recurrence of variable coefficients with two indices

In this paper, we obtain an explicit formula of general solution for a class of the non-homogeneous recurrence of variable coefficients with two indices. Foundation item: Supported by the National Natural Science Foundation of China (19771063) Biography: Yu Chang-an(1948-), male, Professor, research interest: combinatorial theory.     

基于一维散射中心模型的RCS频率全角度外推

目标RCS频率外推是减小目标RCS数据存储的有效手段之一。利用FEKO电磁仿真软件得到目标回波数据,结合经典谱估计算法,提出了一种基于GTD散射中心模型的目标RCS频率全角度外推方法。以弹头目标为例,首先利用1～2GHz频率后向电磁散射数据,提取GTD散射中心模型参数;其次利用RCS频率全角度外推方法,实现了弹头目标在3GHz、4GHz频率上的RCS全角度外推;最后通过将外推数据与FEKO仿真数据进行对比,验证了外推方法的准确性与可靠性。仿真实验表明,外推结果与FEKO的仿真结果在整体趋势及强散射点对应的位置上具有较高的吻合度,可有效描述雷达目标的散射特性。     

A study of quasicrystal structure factors by using quantitative CBED

The procedure of simulating convergent beam electron diffraction (CBED) pattern of quasicrystals by dynamical theory is described. The simulated patterns are generally coincide with the experimental patterns. The variations of intensity distribution in CBED pattern with the amplitude and phase of the structure factor of quasicrystal are calculated with dynamical theory. The sensitivity of intensity distribution to the structure factor is investigated. Foundation item: Supported by the National Natural Science Foundation of China (59871034) Biography: Zhao Chun (1974-), female, Master candidate. Research direction: diffraction physics.     

HMM in predicting protein secondary structure

We introduced a new method—duration Hidden Markov Model (dHMM) to predicate the secondary structure of Protein. In our study, we divide the basic second structure of protein into three parts: H (α-Helix), E (β-sheet) and O (others, include coil and turn). HMM is a kind of probabilistic model which more thinking of the interaction between adjacent amino acids (these interaction were represented by transmit probability), and we use genetic algorithm to determine the model parameters. After improving on the model and fixed on the parameters of the model, we write a program HMMPS. Our example shows that HMM is a nice method for protein secondary structure prediction. Foundation item: Supported by the National Natural Science Foundation of China (30170214) Biography: Huang Jing (1977-), female, Master candidate, research direction: bioinformatics.     

The Global Stability of Predator-Prey System of Gause-Type with Holling Ⅲ Functional Response

This paper deals with the question of global stability of the positive locally asymptotically stable equilibrium in a class of predator-prey system of Gause-type with Holling III functional response. The Dulac's criterion is applied and liapunov functions are constructed to establish the global stability. Foundation item: Supported by the National Natural Science Foundation of China (19531070) Biography: Feng Jian-wen (1964-), male, Ph. D candidate, research interests: the qualitative theory and bifurcation theory of ODE.     

A formula of solution for a class of homogeneous recurrence of variable coefficients with two indices

In this paper, we obtain an explicit formula of general solution for a class of the homogeneous recurrence of variable coefficients with two indices. Foundation item: Supported by the National Natural Science Foundation of China(19771063) Biography: YU Chang-an(1948-), male, Professor, Current research interest is in combinatorial theory     

共享孔径超表面设计及其在提升波导缝隙天线辐射和散射性能中的应用

根据平面阵列散射理论和天线共享孔径思想,提出了一种由完美吸波体(PMA)和人工磁导体(AMC)交错构成的共享孔径超表面(SA-MS),可在同一孔径面上同时实现对电磁波的吸收和相位对消。仿真结果表明由于吸波频段与相位对消频段的级联,该SA-MS相比理想导电体(PEC)、PMA、AMC-PEC具有宽带雷达散射截面(RCS)减缩效果。而后将该SA-MS与波导缝隙天线一体化设计并加工,仿真与实测结果表明:与金属面天线相比,SA-MS天线增益提升了3.3dB,同时RCS在5.52~7.51GHz范围内的减缩在6dB以上,减缩带宽达到30.5%,x、y极化条件下最大减缩量分别达到20.5dB和20.2dB,验证了设计的SA-MS对天线的辐射和散射性能均有提升。