ISSN 
1999 Vol. 28, No. 2
1999, 28(2): 111-115.
Abstract:
This paper gives a modified MUSIC (MMUSIC) algorithm based on the singularity decomposition of the data matrix which is re-constructed by the received data and their conjugatings. This method can change the eigenvalue distributions of the covariance matrix and improve the performances of the signal DOA estimation. With the same SNR and snapshot number, the performances of MMLISIC algorithm are better than that of MUSIC algorithm not only in the estimation of DOA of singals, but also in the resolution of the arrival angle for singals. Finally, the simulation results confirming the theoretical analysis are presented.
This paper gives a modified MUSIC (MMUSIC) algorithm based on the singularity decomposition of the data matrix which is re-constructed by the received data and their conjugatings. This method can change the eigenvalue distributions of the covariance matrix and improve the performances of the signal DOA estimation. With the same SNR and snapshot number, the performances of MMLISIC algorithm are better than that of MUSIC algorithm not only in the estimation of DOA of singals, but also in the resolution of the arrival angle for singals. Finally, the simulation results confirming the theoretical analysis are presented.
1999, 28(2): 116-119.
Abstract:
According to the optimization theory and the neural network (NN) theory,an optimum multiuser detector (MUD) is proposed.The optimum MUD problem is taken as the combinatorial optimum problem.Using the neural network which has the ability of fast optimization computing,the optimization neural network MUD is derived. Theoretical analysis and numerical results show that in the aspect of biterror rate and multiple-access-interference, the optimum MUD is better than the conventional and decorrelated MUD, in aspect of "near-far" resistance, the optimum MUD is better than the conventional MUD, and is worse than the decorrelated detector, and the optimum MUD can be easily implemented by VLSI technology.
According to the optimization theory and the neural network (NN) theory,an optimum multiuser detector (MUD) is proposed.The optimum MUD problem is taken as the combinatorial optimum problem.Using the neural network which has the ability of fast optimization computing,the optimization neural network MUD is derived. Theoretical analysis and numerical results show that in the aspect of biterror rate and multiple-access-interference, the optimum MUD is better than the conventional and decorrelated MUD, in aspect of "near-far" resistance, the optimum MUD is better than the conventional MUD, and is worse than the decorrelated detector, and the optimum MUD can be easily implemented by VLSI technology.
1999, 28(2): 120-123.
Abstract:
Based on the principle of minimum mean square error frequency estimation from phase differences,the new modified frequency estimation methods from phase differences directly for real sinusoidal signal are presented in this paper.The new methods can rapidly and efficiently obtain the informations of a real sinusoidal signal's phase on time domain or frequency domain by zero-crossings or FFT transforming.The modified methods can extend the threshold SNR of frequency estimation,and it is easily implemented.
Based on the principle of minimum mean square error frequency estimation from phase differences,the new modified frequency estimation methods from phase differences directly for real sinusoidal signal are presented in this paper.The new methods can rapidly and efficiently obtain the informations of a real sinusoidal signal's phase on time domain or frequency domain by zero-crossings or FFT transforming.The modified methods can extend the threshold SNR of frequency estimation,and it is easily implemented.
1999, 28(2): 124-127.
Abstract:
Suppose the signal input-rate for ATM is lying on a alternative renewal process (not a Marcov process) and the output-rate is invariable, this paper gives the transient solution for the buffer content using Fluid model and renewal theory. It is useful for the design and control of the ATM multiplexer.
Suppose the signal input-rate for ATM is lying on a alternative renewal process (not a Marcov process) and the output-rate is invariable, this paper gives the transient solution for the buffer content using Fluid model and renewal theory. It is useful for the design and control of the ATM multiplexer.
1999, 28(2): 128-131.
Abstract:
In this paper, an approximate algorithm is proposed for the Mathieu characteristic value.The precision of the improvement method can satisfy general engineering requirement in dealing with the T-MATRIX method to determine large aspect ratio scattering problem of resonant mode(q:650~1000).To get high accuracy in verifying the mentioned above, this paper also put forward a recurrence method tackling continue fraction.
In this paper, an approximate algorithm is proposed for the Mathieu characteristic value.The precision of the improvement method can satisfy general engineering requirement in dealing with the T-MATRIX method to determine large aspect ratio scattering problem of resonant mode(q:650~1000).To get high accuracy in verifying the mentioned above, this paper also put forward a recurrence method tackling continue fraction.
1999, 28(2): 132-135.
Abstract:
In this paper, some problems about IGBT's operation characteristics are discussed. A driving mode called zero voltage commutation and zero current commutation (ZVC/ZCC) technique with high efficiency and safety is introduced. By making use of removing charges and reverse avalanche of IGBT, zero voltage or zero current occurs during the commutation course of IGBT. It is very useful for reducing the effects of tailing and latching and improving the operation efficiency and safety.
In this paper, some problems about IGBT's operation characteristics are discussed. A driving mode called zero voltage commutation and zero current commutation (ZVC/ZCC) technique with high efficiency and safety is introduced. By making use of removing charges and reverse avalanche of IGBT, zero voltage or zero current occurs during the commutation course of IGBT. It is very useful for reducing the effects of tailing and latching and improving the operation efficiency and safety.
1999, 28(2): 136-140.
Abstract:
The ferroelectrics and relaxor ferroelectrics are discussed. It is believed that the solid solutions of barium strontium titanate and lead strontium titanate by conventional process are doped relaxor ferroelectrics. The Heywang's double Schottky barrier model is introduced to explain their U-type resistance-temperature characteristics.
The ferroelectrics and relaxor ferroelectrics are discussed. It is believed that the solid solutions of barium strontium titanate and lead strontium titanate by conventional process are doped relaxor ferroelectrics. The Heywang's double Schottky barrier model is introduced to explain their U-type resistance-temperature characteristics.
1999, 28(2): 141-143.
Abstract:
This paper presents the calculation principle of the temperature, thermal deformation and thermal stress of the piston in internal-combustion engine, and calculates the temperature, thermal deformation and thermal stress of the piston by the method of finite element analysis. This paper also builds up the finite element model and boundary condition for three dimension thermal analysis, and gives the calculating results and conclusion about the design of piston.
This paper presents the calculation principle of the temperature, thermal deformation and thermal stress of the piston in internal-combustion engine, and calculates the temperature, thermal deformation and thermal stress of the piston by the method of finite element analysis. This paper also builds up the finite element model and boundary condition for three dimension thermal analysis, and gives the calculating results and conclusion about the design of piston.
1999, 28(2): 144-147.
Abstract:
The characteristics and the analytical methods of the singular position of a parallel robot are discussed in this paper A singularity analysis of the Plücker coordinate matrix to the DELTA robot is presented. A simple way of using the force analysis to a parallel robot mechanism to determine its singular pasitions is put forward.
The characteristics and the analytical methods of the singular position of a parallel robot are discussed in this paper A singularity analysis of the Plücker coordinate matrix to the DELTA robot is presented. A simple way of using the force analysis to a parallel robot mechanism to determine its singular pasitions is put forward.
1999, 28(2): 148-151.
Abstract:
The harmonic magnetic field under steady operation is analyzed, with computation methods for harmonic current and ripple torque of the induction motor obtained. Analysis shows that the 3Kth harmonic voltage does not initiate the harmonic current and torque while the (3K-1)th harmonic voltage not only produces the same harmonic current and ripple torque as the (3K-2)th harmonic voltage, but also adds a reverse torque to the fundamental and causes a loss. Experiments proves the correctness and effectiveness of the calculating results. Finally, a solution to restraining the harmonic current and ripple torque is suggested, ie a larger modulation frequency ratio of 3K is to be adopted, as it is used in SPWM.
The harmonic magnetic field under steady operation is analyzed, with computation methods for harmonic current and ripple torque of the induction motor obtained. Analysis shows that the 3Kth harmonic voltage does not initiate the harmonic current and torque while the (3K-1)th harmonic voltage not only produces the same harmonic current and ripple torque as the (3K-2)th harmonic voltage, but also adds a reverse torque to the fundamental and causes a loss. Experiments proves the correctness and effectiveness of the calculating results. Finally, a solution to restraining the harmonic current and ripple torque is suggested, ie a larger modulation frequency ratio of 3K is to be adopted, as it is used in SPWM.
1999, 28(2): 152-156.
Abstract:
In this paper, how to find an optimal order using genetic algorithm is discussed. This paper also uses some variable orders found by heuristic method and random orders for population initialization,and utilizes a fast method to compute an order's fitness. The experiment results indicate that this method can find the optimal order in global scope. This method has some reference to the variable ordering of BDD and to the aPPlication of genetic algorithm.
In this paper, how to find an optimal order using genetic algorithm is discussed. This paper also uses some variable orders found by heuristic method and random orders for population initialization,and utilizes a fast method to compute an order's fitness. The experiment results indicate that this method can find the optimal order in global scope. This method has some reference to the variable ordering of BDD and to the aPPlication of genetic algorithm.
1999, 28(2): 157-161.
Abstract:
In this paper,the energy functions for hazard-free delay testing are presented, thus the problem of RRT (restricted robust test) generation for delay faults becomes an energy minimization problem. An improved genetic algorithm for RRT generation is given. This algorithm can inhibit premature convergence by modifying the population size with the degree of the evolution. The experiment shows that this method is effective.
In this paper,the energy functions for hazard-free delay testing are presented, thus the problem of RRT (restricted robust test) generation for delay faults becomes an energy minimization problem. An improved genetic algorithm for RRT generation is given. This algorithm can inhibit premature convergence by modifying the population size with the degree of the evolution. The experiment shows that this method is effective.
1999, 28(2): 162-165.
Abstract:
Local Area Networks(LANs) are good system platforms used in network computing with excellent price/performance ratios. TWT-CAD comprises complicated scientific computing involving various disciplines. The multi-agent oriented model provides TWT-CAD system with the abilities of coordinate computing and distributed data-share while greatly improving its availability, generality, superiority and integrity. Based on the software architecture, twenty-thousand-line Visual C++ codes are developed to run on a Windows NT LAN, visualizing the beam-wave 3D nonlinear interaction. The further work is to optimize and configure its object modules.
Local Area Networks(LANs) are good system platforms used in network computing with excellent price/performance ratios. TWT-CAD comprises complicated scientific computing involving various disciplines. The multi-agent oriented model provides TWT-CAD system with the abilities of coordinate computing and distributed data-share while greatly improving its availability, generality, superiority and integrity. Based on the software architecture, twenty-thousand-line Visual C++ codes are developed to run on a Windows NT LAN, visualizing the beam-wave 3D nonlinear interaction. The further work is to optimize and configure its object modules.
1999, 28(2): 166-170.
Abstract:
In this paper,the space-charge limiting current of coaxial drift tube is derived by the Green's function method. TWo-dimensional features of coaxial vircator is analyzed within the framework of steady-state relativistic-fluid Maxwell equations. The radial current arsing at the anode, and plasma frequency for electron beam can be abtained. The resulting plasma frequency solution agrees with the PIC simulation frequency. MAGIC, a 2(1/2)dimensional particle-in-cell codes are used to simulate the coaxial vircatot The output power, the FFT of output power and the plot of single frequency spectrum, and the time history of current are presented. GW output power is generated with 0.6 MV voltege, and microwave radiation efficiency is about 14.30%.
In this paper,the space-charge limiting current of coaxial drift tube is derived by the Green's function method. TWo-dimensional features of coaxial vircator is analyzed within the framework of steady-state relativistic-fluid Maxwell equations. The radial current arsing at the anode, and plasma frequency for electron beam can be abtained. The resulting plasma frequency solution agrees with the PIC simulation frequency. MAGIC, a 2(1/2)dimensional particle-in-cell codes are used to simulate the coaxial vircatot The output power, the FFT of output power and the plot of single frequency spectrum, and the time history of current are presented. GW output power is generated with 0.6 MV voltege, and microwave radiation efficiency is about 14.30%.
1999, 28(2): 171-174.
Abstract:
S-P FEL quasi-optical open resonator system with three-mirror are introduced in this paper. By means of the diffracted theory of quasi-optical resonator, this paper analyzes and calculates the characteristics of the system by the principle of mirror symmetry and the method of rotating coordinate system. The corresponding model charts and testing results on 3 mm band are given. The numerical simulation and experimental results show that the method is effective.
S-P FEL quasi-optical open resonator system with three-mirror are introduced in this paper. By means of the diffracted theory of quasi-optical resonator, this paper analyzes and calculates the characteristics of the system by the principle of mirror symmetry and the method of rotating coordinate system. The corresponding model charts and testing results on 3 mm band are given. The numerical simulation and experimental results show that the method is effective.
1999, 28(2): 175-177.
Abstract:
A optimum design scheme for 3 dimensions magneto optical card (3DMO card)storage system is presented. The 3DMO card possesses the features of large capacity, erasability and portability. By the use of the fiber optical head, the average access time of the storage system is decreased effectively. Based on the Borland C++, a optical expert system software is set up to simulate and analyze the pick-up signals. The technique is also suitable for the optical head design and simulation analysis of magneto-optical disk and other optical disk storage system.
A optimum design scheme for 3 dimensions magneto optical card (3DMO card)storage system is presented. The 3DMO card possesses the features of large capacity, erasability and portability. By the use of the fiber optical head, the average access time of the storage system is decreased effectively. Based on the Borland C++, a optical expert system software is set up to simulate and analyze the pick-up signals. The technique is also suitable for the optical head design and simulation analysis of magneto-optical disk and other optical disk storage system.
1999, 28(2): 178-180.
Abstract:
The diffraction integral of small Fresnel number focusing laser system is obtained in the presence of aberration.The general approximate formula for the on-axis relative density distribution is also derived,as well as the on-axis relative density distribution formula for a spherical aberration laser system.In the conditions of aberration-free and non-truncation,the formulae can be simplified which fit well with the results obtained by former researchers.
The diffraction integral of small Fresnel number focusing laser system is obtained in the presence of aberration.The general approximate formula for the on-axis relative density distribution is also derived,as well as the on-axis relative density distribution formula for a spherical aberration laser system.In the conditions of aberration-free and non-truncation,the formulae can be simplified which fit well with the results obtained by former researchers.
1999, 28(2): 181-186.
Abstract:
This paper introduces how to realize HTTP Protocol, and how to receive or send HTTP packet. WWW service is also provided.Based on the analysis of the WWW server, this paper gives reference to development of new WWW server in intagrated service broad-band network of CATs phone and computer.
This paper introduces how to realize HTTP Protocol, and how to receive or send HTTP packet. WWW service is also provided.Based on the analysis of the WWW server, this paper gives reference to development of new WWW server in intagrated service broad-band network of CATs phone and computer.
1999, 28(2): 187-190.
Abstract:
This paper describes the realistic significance of using trigger to maintain data's referential integrity in database application system. The basic grammar of creating trigger and deleteing trigger in sybase database application system are introduced, and the temporary table and global variable refered are discussed. At last, the application method and example of using trigger to maintain data's referential integrity are also presented.
This paper describes the realistic significance of using trigger to maintain data's referential integrity in database application system. The basic grammar of creating trigger and deleteing trigger in sybase database application system are introduced, and the temporary table and global variable refered are discussed. At last, the application method and example of using trigger to maintain data's referential integrity are also presented.
1999, 28(2): 191-194.
Abstract:
The software reliability of object-oriented multicomputer systems is closely related with the user profile. In this paper, a Markov model is given for object-oriented multicomputer software reliability with the matrix theory. The effect of every module reliability of computer software system to the whole system reliability(sensitivity) is analyzed and the module reliability allocation meeting the whole software system reliability is discussed. In the end, an example is given.
The software reliability of object-oriented multicomputer systems is closely related with the user profile. In this paper, a Markov model is given for object-oriented multicomputer software reliability with the matrix theory. The effect of every module reliability of computer software system to the whole system reliability(sensitivity) is analyzed and the module reliability allocation meeting the whole software system reliability is discussed. In the end, an example is given.
1999, 28(2): 195-198.
Abstract:
In this paper, an object-oriented approach in CIMS/MIS developing is described,based on a practical CIMS.The hierarchical architecture of the system is presented.The advantages of applying O-O technology in CIAS/MIS developing are analyzed.This paper also presents O-O analysis,O-O design and a development platform to develop the system.Some practical procedures are depicted using the development platform in implementing the system.
In this paper, an object-oriented approach in CIMS/MIS developing is described,based on a practical CIMS.The hierarchical architecture of the system is presented.The advantages of applying O-O technology in CIAS/MIS developing are analyzed.This paper also presents O-O analysis,O-O design and a development platform to develop the system.Some practical procedures are depicted using the development platform in implementing the system.
1999, 28(2): 199-201.
Abstract:
This paper discusses the newest fire-wall system implemented with SOCKS Protocol Version 5 based on client/server model, and its fundamental principle and the implementation protocol are illuminated. The packet format about request and reply betWeen the SOCKS Client and SOCKS Server is given, and its implemented-steps are shown.The distinction betWeen the SOCKS and Proxy are analyzed, Which shows the advantages of the system.
This paper discusses the newest fire-wall system implemented with SOCKS Protocol Version 5 based on client/server model, and its fundamental principle and the implementation protocol are illuminated. The packet format about request and reply betWeen the SOCKS Client and SOCKS Server is given, and its implemented-steps are shown.The distinction betWeen the SOCKS and Proxy are analyzed, Which shows the advantages of the system.
1999, 28(2): 202-206.
Abstract:
This paper discusses the interface technology which used on the connection between the web server and the database on internet.The interface technology develops from CGI, API to JDBC. This paper focuses on the architecture of JDBC interface technology and its implementation program is also given.
This paper discusses the interface technology which used on the connection between the web server and the database on internet.The interface technology develops from CGI, API to JDBC. This paper focuses on the architecture of JDBC interface technology and its implementation program is also given.
1999, 28(2): 207-210.
Abstract:
This paper introduces the origination of the DW ideology and its architecture and principles, as well as relative techniques. The structure of DW of comprehensive query system of factory manager is also discussed. The implementation methods of data collection and data visual appears are presented. Finally, this paper proposes the ways of building an effective decision support system.
This paper introduces the origination of the DW ideology and its architecture and principles, as well as relative techniques. The structure of DW of comprehensive query system of factory manager is also discussed. The implementation methods of data collection and data visual appears are presented. Finally, this paper proposes the ways of building an effective decision support system.
1999, 28(2): 211-215.
Abstract:
In this paper, the cellular neural networks with feedback and delay is studied. By making use of the Lyapunov function, the method variation of parameters is given combining with the trick of inequality analysis. The bounded property of the solution and the asymptotic property of solution for the cellular neural networks with.feedback and delay are proved. The sufficient condition of stability of solution for cellular neural networks with feedback of delay is also discussed
In this paper, the cellular neural networks with feedback and delay is studied. By making use of the Lyapunov function, the method variation of parameters is given combining with the trick of inequality analysis. The bounded property of the solution and the asymptotic property of solution for the cellular neural networks with.feedback and delay are proved. The sufficient condition of stability of solution for cellular neural networks with feedback of delay is also discussed
1999, 28(2): 216-218.
Abstract:
This paper discusses the fixed polarity Reed-Muller (namely FPRM) form of Boolean function, and the Boolean equivalence can be checked through the FPRM form. A novel method is mentioned in this paper Using this method, the exact polarities of both the Boolean function and the FPRM from can be got which largely reduce the workload of Boolean.
This paper discusses the fixed polarity Reed-Muller (namely FPRM) form of Boolean function, and the Boolean equivalence can be checked through the FPRM form. A novel method is mentioned in this paper Using this method, the exact polarities of both the Boolean function and the FPRM from can be got which largely reduce the workload of Boolean.
1999, 28(2): 219-222.
Abstract:
The developing tendency of world economy is the transformation of industrial economy into knowledge. In order to meet the sharp change of the worldwide economic shifting pattern,higher education reform is to be accelerated and higher education concept is to be renovated.At the same time,the developing policies of state-private pattern and various training pattern need to be carried out, and the proportion of information majors should be enlarged.
The developing tendency of world economy is the transformation of industrial economy into knowledge. In order to meet the sharp change of the worldwide economic shifting pattern,higher education reform is to be accelerated and higher education concept is to be renovated.At the same time,the developing policies of state-private pattern and various training pattern need to be carried out, and the proportion of information majors should be enlarged.
