Model and Numerical Analysis of Radiation Field Created by Lightning Overvoltage Wave on Transmission Lines

The radiation field created by the transmission line stroked by lightning far from the lightning channel has been analyzed by the FDTD method.The authors we establish the calculation model and FDTD calculation method of transmission line,and discusses the import of lightning excitation source.The simulation of lightning stroked on a single transmission line in free space or stroked on three-phase high voltage transmission lines in actual environments has been done,and gives the distribution of transient radiation field around the transmission lines when lightning overvoltage wave transmits along the transmission line.The simulation result shows that: the effect of the transient radiation field caused by lightning over voltage wave done with environment is obvious,and the high frequency component of transient radiation field may disturb or do harm to the electronic facility or communication facility around the transmission lines.     

Application of Computer Auxiliary Design Parameterization Technique

Engineering design exists a great deal of similar topology relational graph. It can not achieve these designs only depending on the method of ordinary interactive computer auxiliary design speedily and accurately, however this method of parameterization design can solve this problem through the way of compiling simple computer programming. The authors propose the idea of computer auxiliary design parameterization technique and analyze its essential principle by brief explanation and legend to emerge the new aspect of field of computer auxiliary design of parameterization technique. Meanwhile, together with the simple computer programming, the authors show the specific application of this kind of technique detailed by the example of interior design. By means of wide-ranging application of computer auxiliary design of parameterization technique, numerous engineer and technician's design level must be improved extremely.     

Numerical analysis on the performance of spiral antennas

The surfaces of the Planar Spiral Antennas and Conical Spiral Antennas are analyzed with planar triangle. The surface currents of the antennas are solved by using the Method of Moment (MoM) based on the RWG basis function. The input impedance, directivity, gain, radiated power and radiation field of the antenna can be found. The results indicate that, in very wide frequency band, the value of the input impedance equals to the theoretical value of Self-Compensated antennas (in agreement with Babinet-booker' principle), which is,188.5 ohm , the half of the wave impedance of free space, while the directivity, gain and radiated power are stable within the frequency band. When the antenna is driven by the signal of derivative Gaussian pulse, the radiating electric field waveform is obtained by the Fourier transform. When the spiral antenna is used as the pulse radiation antenna, the waveform of the radiation electric field shows the characteristics of the Gaussian quadratic differential.     

热风与远红外组合加热式蔬菜脱水机的改进设计与试验

针对现有远红外蔬菜脱水机存在的易将表层物料烤黄、水分排除不及时及干燥物料厚度有限等问题,采用热风与远红外辐射相结合的组合干燥技术方案,对现有设备进行改造。改进后的设备引风管和供风管的连接管直径自上而下依次减小,即供给各层干燥箱的热风量和从各层干燥箱的引风量自上而下也相应地减小,满足了各层干燥箱对风量的不同需求。对比试验结果表明,采用热风与远红外组合干燥技术,解决了现有设备存在的问题,提高了脱水速率、干燥质量和能源利用率。     

Application of a FDTD/MOMTD Hybrid Method to the Scattering Problem of the Ground Penetrating Radar

In order to analyze and research the scattering problem of the ground penetrating radar under the ground, a hybrid method combining FDTD and MOMTD is constructed to solve the problem. The curve of current on central feeding point of pick-up antenna is obtained by simulating when different distance between the ideal conductor and the ground is considered, correctness of the result gained by employing the hybrid method is proved through qualitative and quantitative analysis.     

CCD radiation temperature measurement method for hot continuous casting billet surface

According to the present research status and existing problems of hot continuous billet surface temperature non contact measurement technology, a real time temperature measurement model, which combines two-color(R,G) and monochrome (B) of surface radiation image, is established. The surface image is collected through tricolor charge coupled device (CCD) sensor, at the same time, the temperature dynamic response range of CCD can be improved by controlling integrated time and setting different apertures. Through computer image process technology, multi-point temperature can be measured simultaneously, and 2-D temperature field distribution on continuous casting billet surface can be realized. It is be proved by theory and application that the model and method can provide a theory and technology support for realizing surface temperature field on-line measurement for continuous casting billet.     

Calculation of Room Impulse Reponse and Acoustic Parameters by Finite-difference Time-domain Method

The administrator boundaries in room were modeled by digital filters of complex impedance in finite-difference time-domain (FDTD) method. Doors, windows and walls were described respectively by their complex impedance boundaries with digital filters. Impulse responses in a room were calculated with the FDTD model, and typical room acoustics parameters were obtained from the responses. The high correlation coefficients between the calculated and measured impulse responses and the good agreement in acoustic parameters show that sound field in room can be properly simulated by this FDTD model.     

Boundary Element Methods with Overlapping Domain Decomposition for Parabolic Problem

Boundary element method is a numerical method for solving partial differential equations. There are several formulations of boundary element method (BEM) applied to solve a parabolic differential equation.The approach,which employs time- dependent fundamental solution,allows longer time steps in time integration than other approaches,and this can cut down on time for computer implementation with high precision.Domain decomposition method,which decompose the domain that a given problem is to be solved into subdomains,has the advantages of reducing the large problem into smaller ones and reducing the complex problem into simpler ones,and allows parallel computing.An overlapping domain decomposition method is applied combining a boundary element formulation with time-dependent fundamental solution to solve a diffusion equation. Firstly, by domain decomposition, the problem divided into two problems on subdomains, and then the initial-Boundary problems are solved by boundry element method on each subdomain.Some numerical examples are presented to illustrate feasibility and efficiency of the method. The numerical experiments show that the convergence rate of the method is dependent with the overlapping degree of the subdomains.     

A fast scanning method for deep-space exploration antennas〖JP〗

A hybrid multi-beam spiral scanning method for deep-space exploration antennas is proposed, which can be used to estimate the true spacecraft position. Physical optics is used to compute and analyze the far-field pattern of the antenna for excitation of each of the individual array elements. The utilization of a focal-plane array in place of a standard single-mode feed improves the field of view of large high-frequency antenna. Multiple closely overlapping beams are synthesis with conjugate field matching technique. Results show that, combined with spiral scanning method, the multiple beams reflector antenna can reduce the scanning time by one third, and the array gain in multi-beam reflector antenna can improve the distance of deep-space exploration.     

Some Discussion On the Calculation of the Discrete Fourier Transform(DFT)

In the field of signal analyies for time frequency, the DFT is a familiar term. Especially,when its efficient algorithm FFT given, the other operations in signal analyses are also usually translated to DFT as soon as possible so as to enhance the calculating speed. But in our exploning the virtual instrument for time frequency analyzing, two sorts of formulas to calculate DFT and its inverse transform (IDFT) are found. These results are in different value of operation from different signal analysts or from different instruments for time frequency analyzing, their physical meaning are also not clear enough.The period extent theory some previous document based on when defined DFT is firstly expatiated. Then, separately with future defining coefficient method and analogy evolvement method, the authors argue that, based on the period extent theory, it is more rational to calculate DFT with the formula given. A shortage is pointed out and corrected is appeared in some previous documents when having given the formula of DFT. The improper view is also clarified that the reason why there are two sorts of formulas is make by custom.The rationality of the authors view with three examples is visually verified in the end.     

Design of the PC/104 Bus Mode Multi-channel Analyzer

This paper expatiates on the bus structure and develop the bus mode Multi-Channel Analyzer (MCA). The nucleus of this MCA is the PC/104 embedded computer, and it introduces the bus communication to realize system and data communication. It may realize data collecting and showing in the field, because the bus mode is rapid. At first, on the hardware we introduce CMOS components, this reduces power, volume and weight. These make it adapts to use in the field; besides, on the software we adopt C and assembly language to program in order to improve conversion speed. At the same time, single-task DOS operating system is infroduced, which makes the software run more steadily, operate more simply. By means of testing on the spot it can normally work, so it suitable to work in the field.     

Method to Determine the Intersection of Two Arbitrary Solid Polygon With Node Operation

The method to polygon' intersection is applied in computational geometry, computer graphics, GIS, evaluation of geo-hazards and civil engineering. Based on the node state of polygon, the authors propose the method and algorithm of polygon' intersection, the key to which is node operation. This method's concept is simple; and it is easy to computer program's implementation. It avoids to singular problem of Boolean Operation, and is easy to solve the problem of overlapping side and sides intersecting in node of polygon. For the arbitrary way of intersecting of arbitrary solid polygon, this method is accurate and general.     

Software System Protection & Recovery Technology

In order to solve the problem of software system protection and recovery in large computer laboratory , this paper analyses the current state of software system protection & recovery technology and it's defects in safety and stability. The reason causing these problems are discussed. Some solution plans are suggested.The authors hold that there have two way to solve these problems completely , one is strengthening the support from hardware , particularly strengthening the support to recover card directly from BIOS, another is developing new Host/Terminal computer system , protecting software system by ARC.     

Memory Accessing Mechanism of X86 Computer System In Protected Mode

Protecting mode is on importmant working method of X86_based computer system,which provides the hardware support for multi_task and multi_process operation system on X86 platform. During the low_level development of X86_based computer system,it is very important to understand the working method of memory that is a main part of computer system. This paper discusses the data structure and hardware component of X86_based computer system which support the two mechanism of accessing memory:segmenting and paging,as well as the process of converting logical address to linear address and mapping virtual address to physical address. Througn segmenting and paging mechanism,we can realize the independent address space for every process in multi_process system,as well as the measure for protecting the system memory which can prevent the system breakup caused by illegal memory access.     

Algorithm of Circle Analyse in Image Processing

To detect circles fast and correctly has wide application prospect in the field of computer vision and automatic inspection. The conventional Hough transform has the limitation of using too much computation and memory space, and restricted extracting parameter. Aiming at this problem, the authors bring forward a new detection method in allusion to the real-time requirement of detecting circle in simple, image. When the image does not intersect each other, they transform the image into binary image and then perform edge detection to it. After that the chain code of the image is acquired. Basing on that, the circularity of the image and radius of the circle more quickly are calculated and a satisfactory result is gotten.     

利用辐射度模型模拟玉米冠层辐射分布

随着遥感研究的深入和计算机技术的提高,地面目标二向性反射分布函数（BRDF）的研究不断深入,计算机模拟模型因其对植被结构的细致描述并能更真实模拟光线与植被冠层之间的相互作用,受到越来越多的学者重视。本文以2000年在中国科学院栾城生态系统试验站测量的夏玉米为例,在对玉米三维结构进行实地测量的基础上,利用扩展的L系统对生长期的玉米进行建模,进而应用基于真实结构场景的辐射度模型(RGM)计算了玉米场景的二向性反射率因子（BRF）,对模拟结果与实测结果进行了分析与比较,结果显示两者之间具有较好的一致性。证明了辐射度模型用于植被冠层光辐射分布模拟是行之有效的,可以为波谱库提供可靠的多角度数据,并为进一步冠层辐射分布的研究工作奠定了基础。     

Thermal Radiation Effects on Smoke-flow in Atrium Fires

The field models for smoke flow in atrium, takings into account strong buoyancy, turbulence, radiation exchange and wall heat losses are developed according to the characteristics of the atrium fire. Realistic combustion processes in the burning fuel have not been included. A six-flux radiation model is included in a general mathematical model for fires, which are taking as a volumetric heat source, It is applied to the predictions of fire smoke development in a small-scale atrium. In order to avoid complicated radiation exchange models, radiation heat loss effects are combined to the wall heat loss. A General-purpose compute program PHOENICS has been developed to meet this need. Results of numerical calculations based on the field model are compared with test data for a fire in the small-scale atrium test facility. The resullts indicate that radiation transfer has the minor effects, due to the relatively low temperatures encountered. The method that the effect of radiation is included in the calculation of wall heat transfer losses by using maximum heat transfer coefficient is feasible. The field model used in the present study is not good enough, which a turbulent combustion sub-model must be included.     

Application of GDL Computer Technology in the Field of Architecture Informationization

In the Information Age, an urgent problem facing the present-day architecture informationization in China is how to effectively utilize new computer technology to improve production efficiency in the building industry. GDL computer technology is a new technology designed for developing smart and parametric building models. By making an in-depth study of GDL technological theories and its fundamental features and taking into consideration the status quo of its application, the authors put forward the development and application modes of GDL computer technology in the field of architecture informationization and analyze specific solutions as well as its prospects, so as to provide the theoretical basis for and solutions to accelerating the architecture informationization process and offer a new technological means of enhancing productivity in the building industry.     

A Study Transient on Predictive Calculation Method of on Underground Ventilation Network

The authors developed a computer program of transient predictive calculation method on underground ventilation network. The program approximated a field data set of seasonal cyclic changes of air Temperature and humidity at the inlet to the sine curves, and included sensible heat conduction from rock to air current. The temperature of rock around and airway was calculated by finite difference method. The prediction method can be used to calculate the variation of flow rates, temperatures and humidities of air flow in the airways along underground network.     

Designing the Best Incentive Contract Mechanism On Construction Project

This article is established in the Max-profit for both tender and bidder,to their "Win-Win".The most concerned factors-cost,time,quality are taken as the incentive factors at the same time,and are combined in a mathematics model.By using the CPIF contract,the authors establish Stackelberg decision to incentive the both,and then optimize their both profits.Then,they introduce how to use genetic algorithms to compute the model.Finally,the model is illustrated coith an example.