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Artificial Immune Detection for Network Intrusion Data Based on Quantitative Matching Method
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作者 CaiMing Liu Yan Zhang +1 位作者 Zhihui Hu Chunming Xie 《Computers, Materials & Continua》 SCIE EI 2024年第2期2361-2389,共29页
Artificial immune detection can be used to detect network intrusions in an adaptive approach and proper matching methods can improve the accuracy of immune detection methods.This paper proposes an artificial immune de... Artificial immune detection can be used to detect network intrusions in an adaptive approach and proper matching methods can improve the accuracy of immune detection methods.This paper proposes an artificial immune detection model for network intrusion data based on a quantitative matching method.The proposed model defines the detection process by using network data and decimal values to express features and artificial immune mechanisms are simulated to define immune elements.Then,to improve the accuracy of similarity calculation,a quantitative matching method is proposed.The model uses mathematical methods to train and evolve immune elements,increasing the diversity of immune recognition and allowing for the successful detection of unknown intrusions.The proposed model’s objective is to accurately identify known intrusions and expand the identification of unknown intrusions through signature detection and immune detection,overcoming the disadvantages of traditional methods.The experiment results show that the proposed model can detect intrusions effectively.It has a detection rate of more than 99.6%on average and a false alarm rate of 0.0264%.It outperforms existing immune intrusion detection methods in terms of comprehensive detection performance. 展开更多
关键词 Immune detection network intrusion network data signature detection quantitative matching method
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Stiffness-damping matching method of an ECAS system based on LQG control 被引量:9
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作者 陈一锴 何杰 +2 位作者 M.KING 陈无畏 张卫华 《Journal of Central South University》 SCIE EI CAS 2014年第1期439-446,共8页
A novel method of matching stiffness and continuous variable damping of an ECAS(electronically controlled air suspension) based on LQG(linear quadratic Gaussian) control was proposed to simultaneously improve the road... A novel method of matching stiffness and continuous variable damping of an ECAS(electronically controlled air suspension) based on LQG(linear quadratic Gaussian) control was proposed to simultaneously improve the road-friendliness and ride comfort of a two-axle school bus.Taking account of the suspension nonlinearities and target-height-dependent variation in suspension characteristics,a stiffness model of the ECAS mounted on the drive axle of the bus was developed based on thermodynamics and the key parameters were obtained through field tests.By determining the proper range of the target height for the ECAS of the fully-loaded bus based on the design requirements of vehicle body bounce frequency,the control algorithm of the target suspension height(i.e.,stiffness) was derived according to driving speed and road roughness.Taking account of the nonlinearities of a continuous variable semi-active damper,the damping force was obtained through the subtraction of the air spring force from the optimum integrated suspension force,which was calculated based on LQG control.Finally,a GA(genetic algorithm)-based matching method between stepped variable damping and stiffness was employed as a benchmark to evaluate the effectiveness of the LQG-based matching method.Simulation results indicate that compared with the GA-based matching method,both dynamic tire force and vehicle body vertical acceleration responses are markedly reduced around the vehicle body bounce frequency employing the LQG-based matching method,with peak values of the dynamic tire force PSD(power spectral density) decreased by 73.6%,60.8% and 71.9% in the three cases,and corresponding reduction are 71.3%,59.4% and 68.2% for the vehicle body vertical acceleration.A strong robustness to variation of driving speed and road roughness is also observed for the LQG-based matching method. 展开更多
关键词 matching method electronically controlled air suspension linear quadratic Gaussian genetic algorithm
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Assessing validation of dual fluoroscopic image matching method for measurement of in vivo spine kinematics 被引量:8
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作者 BAI Jian-qiang HU Yong-cheng +4 位作者 DULi-qing HE Jing-liang LIU Kai LIU Zhongjun XIA Qun 《Chinese Medical Journal》 SCIE CAS CSCD 2011年第11期1689-1694,共6页
Background Accurate knowledge of the spinal structural functions is critical to understand the biomechanical factors that affect spinal pathology. Many studies have investigated the human vertebral motion both in vitr... Background Accurate knowledge of the spinal structural functions is critical to understand the biomechanical factors that affect spinal pathology. Many studies have investigated the human vertebral motion both in vitro and in vivo. However, determination of in vivo motion of the vertebrae under physiologic loading conditions remains a challenge in biomedical engineering because of the limitations of current technology and the complicated anatomy of the spine. Methods For in vitro validation, a human lumbar specimen was imbedded with steel beads and moved to a known distance by an universal testing machine (UTM). 展开更多
关键词 lumbar spine VALIDATION dual fluoroscopes matching method
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Coordinate difference homogenization matching method for motion correction in 3D range-intensity correlation laser imaging
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作者 Liang Sun Xinwei Wang +4 位作者 Pengdao Ren Pingshun Lei Songtao Fan Yan Zhou and Yuliang Liu 《Chinese Optics Letters》 SCIE EI CAS CSCD 2017年第10期95-98,共4页
This Letter proposes a coordinate difference homogenization matching method to solve motion influence in three-dimensional(3D) range-intensity correlation laser imaging. Firstly, features and feature pairs of gate i... This Letter proposes a coordinate difference homogenization matching method to solve motion influence in three-dimensional(3D) range-intensity correlation laser imaging. Firstly, features and feature pairs of gate images are obtained by speeded-up robust figures and bi-directional feature matching methods. The original mean value of the feature-pair coordinate differences is calculated. Comparing the coordinate differences with the original mean value, the wrong feature pairs are removed, and then an optimized mean value is updated. The final feature-pair coordinates are re-registered based on the updated mean value. Thus, an accurate transformation is established to rectify motion gate images for 3D reconstruction. In the experiment, a 3D image of a tower at 780 m is successfully captured by our laser gated imaging system on a pan-tilt device. 展开更多
关键词 Coordinate difference homogenization matching method for motion correction in 3D range-intensity correlation laser imaging CDH
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REQUIREMENTS AND DESIGN METHOD FOR MATCHING AIRCRAFT GUNS WITH THEIR SUPPORTING STRUCTURE
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《Chinese Journal of Aeronautics》 SCIE EI CAS 1988年第2期105-109,共5页
In aircraft structural dynamic design the matching of guns with their supporting structure is one of the most important tasks on which hinges the success or failure of the structural design. The design curves for matc... In aircraft structural dynamic design the matching of guns with their supporting structure is one of the most important tasks on which hinges the success or failure of the structural design. The design curves for matching guns with their supporting structure can be obtained from response calculations of the plate-spring system supporting the gun on the ground,the model structure tested on the ground and the actual structure.A set of matching curves is given for engineering application.Then,the matching design can be accomplished by means of impact load spectrograms so as to perform an optimal structural design and to make further improvements on dynamic design program. 展开更多
关键词 REQUIREMENTS AND DESIGN method FOR matching AIRCRAFT GUNS WITH THEIR SUPPORTING STRUCTURE
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MODEL AND METHOD OF WELL TEST ANALYSIS FORWELLS WITH VERTICAL FRACTURE
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作者 郭大立 曾晓慧 +1 位作者 赵金洲 刘慈群 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2005年第5期571-578,共8页
Based on the flow mechanism of hydraulic fractured wells, through integrating linear-flow model and effective well-radius model, a new model of well test analysis for wells with vertical fracture was established. In t... Based on the flow mechanism of hydraulic fractured wells, through integrating linear-flow model and effective well-radius model, a new model of well test analysis for wells with vertical fracture was established. In the model, wellbore storage, the damage in the wall of fracture and all kinds of boundary conditions are considered. The model is concise in form, has intact curves and computes fast, which may meet the demand of real-time computation and fast responded well test interpretation. A new method to determine effective well radius was presented, and the correlation between effective well radius and the fracture length, fracture conductivity, skin factor of fracture was given. Matching flow rate or pressure tested, the optimization model that identified formation and fracture parameters was set up. The automatic matching method was presented by synthetically using step by step linear least square method and sequential quadratic programming. At last, the application was also discussed. Application shows that all of these results can analyze and evaluate the fracturing treatment quality scientifically and rationally, instruct and modify the design of fracturing and improve fracturing design level. 展开更多
关键词 vertical fracture well test fluid flow through porous medium MODEL automatic matching method
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Thermoelastic Analysis of Non-uniform Pressurized Functionally Graded Cylinder with Variable Thickness Using First Order Shear Deformation Theory(FSDT) and Perturbation Method 被引量:1
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作者 KHOSHGOFTAR M J MIRZAALI M J RAHIMI G H 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第6期1149-1156,共8页
Recently application of functionally graded materials(FGMs) have attracted a great deal of interest. These materials are composed of various materials with different micro-structures which can vary spatially in FGMs... Recently application of functionally graded materials(FGMs) have attracted a great deal of interest. These materials are composed of various materials with different micro-structures which can vary spatially in FGMs. Such composites with varying thickness and non-uniform pressure can be used in the aerospace engineering. Therefore, analysis of such composite is of high importance in engineering problems. Thermoelastic analysis of functionally graded cylinder with variable thickness under non-uniform pressure is considered. First order shear deformation theory and total potential energy approach is applied to obtain the governing equations of non-homogeneous cylinder. Considering the inner and outer solutions, perturbation series are applied to solve the governing equations. Outer solution for out of boundaries and more sensitive variable in inner solution at the boundaries are considered. Combining of inner and outer solution for near and far points from boundaries leads to high accurate displacement field distribution. The main aim of this paper is to show the capability of matched asymptotic solution for different non-homogeneous cylinders with different shapes and different non-uniform pressures. The results can be used to design the optimum thickness of the cylinder and also some properties such as high temperature residence by applying non-homogeneous material. 展开更多
关键词 non-homogenous cylinder First order Shear Deformation Theory matched asymptotic method perturbation method functionally graded material
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Modified OMP method for multi-target parameter estimation in frequency-agile distributed MIMO radar 被引量:3
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作者 XING Wenge ZHOU Chuanrui WANG Chunlei 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2022年第5期1089-1094,共6页
Introducing frequency agility into a distributed multipleinput multiple-output(MIMO)radar can significantly enhance its anti-jamming ability.However,it would cause the sidelobe pedestal problem in multi-target paramet... Introducing frequency agility into a distributed multipleinput multiple-output(MIMO)radar can significantly enhance its anti-jamming ability.However,it would cause the sidelobe pedestal problem in multi-target parameter estimation.Sparse recovery is an effective way to address this problem,but it cannot be directly utilized for multi-target parameter estimation in frequency-agile distributed MIMO radars due to spatial diversity.In this paper,we propose an algorithm for multi-target parameter estimation according to the signal model of frequency-agile distributed MIMO radars,by modifying the orthogonal matching pursuit(OMP)algorithm.The effectiveness of the proposed method is then verified by simulation results. 展开更多
关键词 distributed multiple-input multiple-output(MIMO)radar multi-target parameter estimation frequency agility modified orthogonal matching pursuit(OMP)method
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SERIES PERTURBATIONS APPROXIMATE SOLUTIONS TO N-S EQUATIONS AND MODIFICATION TO ASYMPTOTIC EXPANSION MATCHED METHOD
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作者 李大鸣 张红萍 高永祥 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2002年第8期963-972,共10页
A method that series perturbations approximate solutions to N-S equations with boundary conditions was discussed and adopted. Then the method was proved in which the asymptotic solutions of viscous fluid flow past a s... A method that series perturbations approximate solutions to N-S equations with boundary conditions was discussed and adopted. Then the method was proved in which the asymptotic solutions of viscous fluid flow past a sphere were deducted. By the ameliorative asymptotic expansion matched method, the matched functions, are determined easily and the ameliorative curve of drag coefficient is coincident well with measured data in the case that Reynolds number is less than or equal to 40 000. 展开更多
关键词 asymptotic expansion matched method series perturbation N-S equation viscous fluid flow past a sphere
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Analysis of circular-to-circular groove waveguide junction 被引量:1
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作者 崔立成 杨鸿生 《Journal of Southeast University(English Edition)》 EI CAS 2003年第1期17-21,共5页
Mode matching method is used to analyze the scattering characteristics of thecircular-to-circular groove waveguide junction. Matching the electric fields and magnetic fields atthe boundary of the junction, and multipl... Mode matching method is used to analyze the scattering characteristics of thecircular-to-circular groove waveguide junction. Matching the electric fields and magnetic fields atthe boundary of the junction, and multiplying the mode functions of the circular waveguide andcircular groove waveguide on both sides of the boundary equation, the scattering matrix equation isobtained, the scattering coefficients can be obtained from the equation. Then the scatteringcharacteristics of the iris with circular window in circular groove waveguide are analyzed. At lastthe convergent problem is discussed; when choosing a suitable mode group, convergent numericalresults are obtained, and the frequency response of the iris' scattering coefficients is also given. 展开更多
关键词 circular groove waveguide circular-to-circular groove waveguide junction mode matching method
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Research on Network Delays of Networked Control Systems 被引量:3
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作者 马向华 谢剑英 魏震 《Journal of Shanghai Jiaotong university(Science)》 EI 2005年第1期25-29,共5页
In networked control systems (NCS), the main problem is time delays induced by communication network, which can deteriorate the performance of the systems, even cause the systems instability. If we know the exact netw... In networked control systems (NCS), the main problem is time delays induced by communication network, which can deteriorate the performance of the systems, even cause the systems instability. If we know the exact network delays, we can compensate for their effect by modifying the parameters of the controller. Hence how to get the knowledge of these delays in the network is critical. This paper analyzed the different characteristics of network delays from sensor to controller and from controller to actuator and presented the methods of online evaluation of these delays. The experiment shows these methods are valid. 展开更多
关键词 networked control systems (NCS) network delays online delay evaluation average delays window closest matching method
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A New Method for Analyzing Heat Exchangers- Matching of Temperature Field 被引量:2
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作者 WANG HuanGuang HUAI XiuLan 《Journal of Thermal Science》 SCIE EI CAS CSCD 2012年第5期452-458,共7页
In heat exchangers, the magnitude of Nu of each duct is influenced by the temperature field, since the ratio of heat capacity rate will influence the matching status of the temperature field between contacting ducts, ... In heat exchangers, the magnitude of Nu of each duct is influenced by the temperature field, since the ratio of heat capacity rate will influence the matching status of the temperature field between contacting ducts, the total heat transfer coefficient is related with the ratio of heat capacity rate. Considering this relationship, a new method for analyzing heat exchanger is proposed - matching of temperature field. First, for a single duct with the temperature field varying exponentially along the flow direction, its Nu is calculated. Then under the hypothesis that the thermal resistance of the wall is negligible, the matching condition was set like this: both the temperature and heat flux are equal for the hot and cold fluids at the wall, so the matching relationship of parameter that describes the temperature field of the hot and cold fluids, was obtained. Finally the relationship between the total Nu and the ratio of heat capacity rate along with the ratio of inherent thermal resistance is obtained. Compared with traditional analyzing methods, the temperature matching method can be used to get the total heat transfer coefficient directly, and also be used for optimization of heat exchanger design. For a parallel flow, the optimal ratio of heat capacity rate is reciprocal to the ratio of inherent thermal resistance, and for a counter flow, the optimal ratio of heat capacity rate is zero or infinity. 展开更多
关键词 matching method heat exchanger ratio of heat capacity rate ratio of inherent thermal resistance
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SIMULTANEOUS MULTIPLE TARGET RECOGNITION USING POLARIZATION AGILE WAVES 被引量:2
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作者 Chen Xinwei Zhao Jianzhong Wu Wen 《Journal of Electronics(China)》 2012年第3期237-241,共5页
A novel matching method for simultaneous multi-target recognition is proposed by jointly considering target's prior scattering knowledge and the polarization parameters of radar echoes. The matching coefficients a... A novel matching method for simultaneous multi-target recognition is proposed by jointly considering target's prior scattering knowledge and the polarization parameters of radar echoes. The matching coefficients are calculated for the judgment. MATLAB simulations show that several targets can be accurately recognized simultaneously, and a high recognition probability can be achieved in Monte Carlo simulations. The total execution time can be remarkably reduced in the Field Programmable Gate Array (FPGA) implementation of the matching procedure. 展开更多
关键词 matching method Multiple target recognition Polarization agile waves Field Programmable Gate Arrays (FPGA)
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Linear theory of beam–wave interaction in double-slot coupled cavity travelling wave tube 被引量:1
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作者 何昉明 谢文球 +2 位作者 罗积润 朱敏 郭炜 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第3期424-427,共4页
A three-dimensional model of the double-slot coupled cavity slow-wave structure (CCSWS) with a solid round elec- tron beam for the beam-wave interaction is presented. Based on the "cold" dispersion, the "hot" di... A three-dimensional model of the double-slot coupled cavity slow-wave structure (CCSWS) with a solid round elec- tron beam for the beam-wave interaction is presented. Based on the "cold" dispersion, the "hot" dispersion equation is derived with the Maxwell equations by using the variable separation method and the field-matching method. Through numerical calculations, the effects of the electron beam parameters and the staggered angle between adjacent walls on the linear gain are analyzed. 展开更多
关键词 double-slot coupled cavity slow-wave structure beam-wave interaction field matching method small signal gain
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Determination of total sulfur in geothermal water by inductively coupled plasma-atomic emission spectrometry 被引量:1
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作者 Bing-bing Liu Mei Han +3 位作者 Jia Liu Na Jia Chen-ling Zhang Lin Zhang 《Journal of Groundwater Science and Engineering》 2022年第3期285-291,共7页
Sulfur speciation and concentration in geothermal water are of great significance for the research and utilization of the water resources.In most situations,it is necessary to determine the total sulfur in geothermal ... Sulfur speciation and concentration in geothermal water are of great significance for the research and utilization of the water resources.In most situations,it is necessary to determine the total sulfur in geothermal water.In this study,the method was established for the determination of determining total sulfur content-the inductively coupled plasma-atomic emission spectrometry(ICP-AES),with the wavelength of 182.034 nm selected in spectral line of sulfur.It was identified that the optimal working conditions of the ICP-AES instrument were 1200 W for high frequency generator power 9 mm for vertical observation height,0.30 MPa atomizer pressure,and 50 r/min analytical pump speed.The matrix interference of the method was eliminated by the matrix matching method.Using this method,sulfur detection limit and minimum quantitative detection limit were 0.028 mg/L and 0.110 mg/L,respectively,whilst the linear range was 0.0-100.0 mg/L.The recovery rate of sample was between 90.67%and 108.7%,and the relative standard deviation(RSD)was between 0.36%and 2.14%.The method was used to analyze the actual samples and the results were basically consistent with the industry standard method.With high analysis efficiency,the method has low detection limit and minimum quantitative detection limit,wide linear range,good precision and accuracy,and provides an important detection method for the determination of total sulfur in geothermal water. 展开更多
关键词 High frequency generator power Vertical observation height Atomizer pressure Matrix matching method Standard addition method
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A novel four-legged loaded element thick-screen frequency selective surface with a stable performance
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作者 唐光明 苗俊刚 董金明 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第12期518-525,共8页
A thick-screen frequency selective surface (FSS) has not only a broad bandwidth but also the advantages of overcoming the multilayer FSS shortcoming of complex structure and low transmittance of centre frequency due... A thick-screen frequency selective surface (FSS) has not only a broad bandwidth but also the advantages of overcoming the multilayer FSS shortcoming of complex structure and low transmittance of centre frequency due to the cascade of FSSs, and this means it could potentially be applied in a stealth curved streamlined radome. However, there is an unsteadiness of centre frequency in a wide range of incident angles and another unsteadiness of polarization in a big incident angle. In order to solve these problems, in this paper we provide a novel four-legged loaded element thick-screen FSS. The structure is analysed and simulated using the mode matching method and moment method. The centre frequency, the transmittance of centre frequency, and bandwidth of the structure are investigated when some parameters including the polarization at a big incident angle and the incident angles of TE &: TM waves are changed. The novel four-legged loaded element thick-screen FSS has better transmission properties with a better steadiness of polarization and incident angle independence. The novel structure of the four-legged loaded element thick-screen FSS provides a valuable reference for their application in a stealth curved streamlined radome. 展开更多
关键词 thick-screen frequency selective surfaces (FSS) mode matching method moment method incident angles independence polarization independence
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CALCULATION AND IMPROVEMENT OF DYNAMIC CHARACTERISTICS OF CENTRIFUGE
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作者 Yang Yun Wang Zheng Department of Engineering Mechanics, Qinghua University Kim Lock Song Institute of Biophysics, Chinese Academy of Sciences 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2001年第1期32-35,39,共5页
The modeling of the rotor support system of a typical centrifuge is discussed. The impedance matching method, cooperating with Riccati transfer matrix method and modal analysis method are adopted to calculate its dyn... The modeling of the rotor support system of a typical centrifuge is discussed. The impedance matching method, cooperating with Riccati transfer matrix method and modal analysis method are adopted to calculate its dynamic characteristics. The influences of the main parts to the critical speeds are analyzed. Based on the analysis, a critical speed in the operating speed range is tuned successfully, and thus the dynamic characteristics of the centrifuge are much improved. 展开更多
关键词 CENTRIFUGE Dynamic characteristics Impedance matching method
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Scattering Characteristics of Metallic Plates in Radial Waveguide
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作者 李相强 刘庆想 +1 位作者 赵柳 张健穹 《Journal of Southwest Jiaotong University(English Edition)》 2010年第3期244-249,共6页
Mode matching is a useful method to analyze the mode characteristics during the section change of a waveguide. By applying this method to the radial waveguide, and solving specific problems due to the radial transmiss... Mode matching is a useful method to analyze the mode characteristics during the section change of a waveguide. By applying this method to the radial waveguide, and solving specific problems due to the radial transmission of electromagnetic wave, this presents a calculating method in radial waveguide based on mode matching. The scattering characteristics of metallic plates in the radial waveguide are calculated, and verified qualitatively using an electromagnetic simulator, which confirmed the validity of this method. 展开更多
关键词 Mode matching method Radial waveguide Metallic plate Scattering characteristics
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Integration of Agricultural Census and Population Census Data
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作者 Eva Laczka 《Journal of Mathematics and System Science》 2013年第12期602-607,共6页
In Hungary a general agricultural census (AC) was carried out in 2000, followed in 2001 by the population and housing census. The two censuses had been designed separately. Originally the Hungarian Central Statistic... In Hungary a general agricultural census (AC) was carried out in 2000, followed in 2001 by the population and housing census. The two censuses had been designed separately. Originally the Hungarian Central Statistical Office (HCSO) did not plan the joint analysis of the data of the two censuses. Following the censuses users and researchers expressed the view that linking the data of the two databases would represent a value-added in the use of the data and the joint utilization of the databases of the two censuses was examined. The databases were matched and the aggregated handling of the information increased the potential for analysing both censuses and allowed further, more sophisticated investigations. By means of the databases of the two censuses, the first opportunity arose for matching the discrete data of the surveys. The precondition of the matching of the data was the conformity of the respective metadata of the two operations. ,,Private holding" and ,,dwelling-household" were the categories applicable as the smallest unit for the matching. The links between the private holdings and the households could be based on the identity of the persons living in the dwelling. The matching of the data required the use of individual identity codes. With the matching process used a joint database of the agricultural and population censuses was set up providing new approaches for gender disaggregated analysis. By using the linked database, the HCSO issued a series of publications on the households living in agricultural private holdings in the countryside. This presentation describes the method of matching the databases of the two censuses. 展开更多
关键词 Censuses integration of censuses matching method
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Dynamics of Vapor Bubble in a Variable Pressure Field 被引量:2
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作者 Kirill V.Rozhdestvensky 《Journal of Marine Science and Application》 CSCD 2022年第3期83-98,共16页
This paper presents analytical and numerical results of vapor bubble dynamics and acoustics in a variable pressure field.First,a classical model problem of bubble collapse due to sudden pressure increase is introduced... This paper presents analytical and numerical results of vapor bubble dynamics and acoustics in a variable pressure field.First,a classical model problem of bubble collapse due to sudden pressure increase is introduced.In this problem,the Rayleigh–Plesset equation is treated considering gas content,surface tension,and viscosity,displaying possible multiple expansion–compression cycles.Second,a similar investigation is conducted for the case when the bubble originates near the rounded leading edge of a thin and slightly curved foil at a small angle of attack.Mathematically the flow field around the foil is constructed using the method of matched asymptotic expansions.The outer flow past the hydrofoil is described by linear(small perturbations)theory,which furnishes closed-form solutions for any analytical foil.By stretching local coordinates inversely proportionally to the radius of curvature of the rounded leading edge,the inner flow problem is derived as that past a semi-infinite osculating parabola for any analytical foil with a rounded leading edge.Assuming that the pressure outside the bubble at any moment of time is equal to that at the corresponding point of the streamline,the dynamics problem of a vapor bubble is reduced to solving the Rayleigh-Plesset equation for the spherical bubble evolution in a time-dependent pressure field.For the case of bubble collapse in an adverse pressure field,the spectral parameters of the induced acoustic pressure impulses are determined similarly to equivalent triangular ones.The present analysis can be extended to 3D flows around wings and screw propellers.In this case,the outer expansion of the solution corresponds to a linear lifting surface theory,and the local inner flow remains quasi-2D in the planes normal to the planform contour of the leading edge of the wing(or screw propeller blade).Note that a typical bubble contraction time,ending up with its collapse,is very small compared to typical time of any variation in the flow.Therefore,the approach can also be applied to unsteady flow problems. 展开更多
关键词 Thin foil theory Matched expansions method Rayleigh-Plesset equation Bubble cavitation Vapor bubble dynamics Bubble collapse Cavitation noise spectra
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