ISSN 
1999 Vol. 28, No. 1
1999, 28(1): 1-5.
Abstract:
In this paper, after modelling the mobile channel with a two state Markov chain, the performances(packet error rate,throughput efficiency and transmission delay) of truncated RS/type Ⅱ hybrid ARQ protocol in this fading channel are analyzed and simulated.It is found that,based upon the powerful error correcting capability of RS code,low transmission delay and packet error rate can be obtained by restricting numbers of retransmission.
In this paper, after modelling the mobile channel with a two state Markov chain, the performances(packet error rate,throughput efficiency and transmission delay) of truncated RS/type Ⅱ hybrid ARQ protocol in this fading channel are analyzed and simulated.It is found that,based upon the powerful error correcting capability of RS code,low transmission delay and packet error rate can be obtained by restricting numbers of retransmission.
1999, 28(1): 6-9.
Abstract:
Phase unwrapping of the interferometric SAR is a very important step to obtain an accurate DEM (Digital Elevation Model). By using a recurrence estimating method, this paper describes a kind of method for phase unwrapping of INSAR. Starting from given initial phase values or adjacent unwrapped phase, the phase estimation values are sequentially obtained by the recurrence relation. Then by the measure of confidence of the phase estimation valuse, the unwrapping phase values of high reliability can be obtained. By using the approach, the simulating experiment is undertaken. The result shows that the method successfully unwraps the phase and the error caused by the algorithm is also very small.
Phase unwrapping of the interferometric SAR is a very important step to obtain an accurate DEM (Digital Elevation Model). By using a recurrence estimating method, this paper describes a kind of method for phase unwrapping of INSAR. Starting from given initial phase values or adjacent unwrapped phase, the phase estimation values are sequentially obtained by the recurrence relation. Then by the measure of confidence of the phase estimation valuse, the unwrapping phase values of high reliability can be obtained. By using the approach, the simulating experiment is undertaken. The result shows that the method successfully unwraps the phase and the error caused by the algorithm is also very small.
1999, 28(1): 10-13.
Abstract:
This paper mainly introduced Linking Protection(LP) scheme and the encryption algorithm adopted in it,which aims at resolving the vulnerability of the automatic link establishment(ALE) system's security The algorithm's realiability is proved by lots ofteses; And the performance of LP scheme is analyed by simulating. The results of the simulation prove that the scheme enchances the system's security, however duing to the word synchronization, it affects the performance a little.
This paper mainly introduced Linking Protection(LP) scheme and the encryption algorithm adopted in it,which aims at resolving the vulnerability of the automatic link establishment(ALE) system's security The algorithm's realiability is proved by lots ofteses; And the performance of LP scheme is analyed by simulating. The results of the simulation prove that the scheme enchances the system's security, however duing to the word synchronization, it affects the performance a little.
1999, 28(1): 14-19.
Abstract:
In this paper, a new non-linear vector filters for removing impulse noise is presented,which are efficient. One of the filters performs almost the same as VMF, while the computational efforts is decreased remarkably All the new filters are quite simple compared with VMF, and easy to be realized by hardware.
In this paper, a new non-linear vector filters for removing impulse noise is presented,which are efficient. One of the filters performs almost the same as VMF, while the computational efforts is decreased remarkably All the new filters are quite simple compared with VMF, and easy to be realized by hardware.
1999, 28(1): 20-23.
Abstract:
In the is paper, several wideband digital quadrature technique are discussed, including FFT transforming and discrete filter based on Hilbert transforming. A special quadrature sampling technique for arbitrary bandpass signal within bassband sample rate is also presented.Their performances with the quadrature principles of Gram-Schmidt are analyzed the errors of I and Q correction are given The computer stimulations show that in wide range of input frequency expect for discrecte filter,the other methods can obtain very low image power relative to the primary response.
In the is paper, several wideband digital quadrature technique are discussed, including FFT transforming and discrete filter based on Hilbert transforming. A special quadrature sampling technique for arbitrary bandpass signal within bassband sample rate is also presented.Their performances with the quadrature principles of Gram-Schmidt are analyzed the errors of I and Q correction are given The computer stimulations show that in wide range of input frequency expect for discrecte filter,the other methods can obtain very low image power relative to the primary response.
1999, 28(1): 24-27.
Abstract:
Phase noise and spurious spectrum are the key characters in direct digital synthesizers (DDS) applied in the high stable frequency source. Actually, the poor performance of spurious spectrum from DDS has always restrained its applications. This paper introduces a new way to analyze the spurious spectrum and phase noise generated by the phase truncation. The locations and amplitudes of spurious spectrum are precisely dtermined. Phase noise generated by the size of ROM look-up table and the performance of DAC is also investigated.
Phase noise and spurious spectrum are the key characters in direct digital synthesizers (DDS) applied in the high stable frequency source. Actually, the poor performance of spurious spectrum from DDS has always restrained its applications. This paper introduces a new way to analyze the spurious spectrum and phase noise generated by the phase truncation. The locations and amplitudes of spurious spectrum are precisely dtermined. Phase noise generated by the size of ROM look-up table and the performance of DAC is also investigated.
1999, 28(1): 28-31.
Abstract:
This paper theoretically analyzes the relationship between white noise and power spectrum of linear frequency modulation continuous wave (LFMCM) radar and the influence of white noise on its range-precision and range-resolution. The result is derived that LFMCW radar has higher anti-noise property which adopts the structure of Beat-FFT than that of Average Frequency Counter
This paper theoretically analyzes the relationship between white noise and power spectrum of linear frequency modulation continuous wave (LFMCM) radar and the influence of white noise on its range-precision and range-resolution. The result is derived that LFMCW radar has higher anti-noise property which adopts the structure of Beat-FFT than that of Average Frequency Counter
1999, 28(1): 32-36.
Abstract:
suspended coplanar waveguide have the adventages of both finline and suspended stripline.In this paper suspended coplanar waveguides are analyzed using conformal mapping techniques,and the exact solutions are obtained.Analytic closed-form expersessions for the effective dielectric constant,the capacitance per unit length and the characterisitic impedance of the suspended coplanar waveguides with dielectric substrate of finite thickness are given.
suspended coplanar waveguide have the adventages of both finline and suspended stripline.In this paper suspended coplanar waveguides are analyzed using conformal mapping techniques,and the exact solutions are obtained.Analytic closed-form expersessions for the effective dielectric constant,the capacitance per unit length and the characterisitic impedance of the suspended coplanar waveguides with dielectric substrate of finite thickness are given.
1999, 28(1): 37-40.
Abstract:
The wave equation of electric in the waveguide can be translated into a coupled difference equation of second order by centered difFerency approximation. This coupled difference equation can be reduced to a very compact decoupled difference equation which contains only one electric component, the Ey, when the discontinuity under investigating only relates to the x-direction in the rectangular waveguide. This difference eqiiation can be computed simply and the memory of computer as well as the CPU time are saved greatly comparing with the conventional FDTD algorithm. The condition of its stability, the dividing of the spatial grid and the absorbing condition of the algorithm are given and compared with the conventional FDTD method. Both data examples computed by the new algorithm and published ones are presented,which show a good agreement.
The wave equation of electric in the waveguide can be translated into a coupled difference equation of second order by centered difFerency approximation. This coupled difference equation can be reduced to a very compact decoupled difference equation which contains only one electric component, the Ey, when the discontinuity under investigating only relates to the x-direction in the rectangular waveguide. This difference eqiiation can be computed simply and the memory of computer as well as the CPU time are saved greatly comparing with the conventional FDTD algorithm. The condition of its stability, the dividing of the spatial grid and the absorbing condition of the algorithm are given and compared with the conventional FDTD method. Both data examples computed by the new algorithm and published ones are presented,which show a good agreement.
1999, 28(1): 41-44.
Abstract:
Electrorheological fluids (ER fluids) are typical non-aqueous suspension consisting of dielectric particles dispersed in non-conducting fluids, which show a reversible viscosity increase upon application of an external electric field. According to the obvious changes of the transmittance of ER fluids under an applied electric field, an assumption on the application of ER fluids to smart windows is presented in this paper. Applying and removing an electric field of 500 V.mm-1, a reversible solar transmittance change as much as 42.0% at the wavelength of 500 nm is experimentally obtained.
Electrorheological fluids (ER fluids) are typical non-aqueous suspension consisting of dielectric particles dispersed in non-conducting fluids, which show a reversible viscosity increase upon application of an external electric field. According to the obvious changes of the transmittance of ER fluids under an applied electric field, an assumption on the application of ER fluids to smart windows is presented in this paper. Applying and removing an electric field of 500 V.mm-1, a reversible solar transmittance change as much as 42.0% at the wavelength of 500 nm is experimentally obtained.
1999, 28(1): 45-48.
Abstract:
Feature-based design method is one of the key techniques in the integration of CAD/CAM which includes completed information of a product. A feature-based part design system based on AutoCAD——AutoCAD feature-based pat design system (AFPD) is developed. In this paper, the design concept the system structure and each module within AFPD are discussed.
Feature-based design method is one of the key techniques in the integration of CAD/CAM which includes completed information of a product. A feature-based part design system based on AutoCAD——AutoCAD feature-based pat design system (AFPD) is developed. In this paper, the design concept the system structure and each module within AFPD are discussed.
1999, 28(1): 49-53.
Abstract:
A fast genetic algorithm——GSAGA(generalized self-adaptive genetic algorithm) is presented in this paper First,evenly distributed initial population is generated. Then, high quality immigrants are introduced according to the condition ofthe population schema. Finally, crossover and mutation are operated on self-adaptively in GSAGA, the searching performance and global convergence are greatly improved compared with many existing genetic algorithms. Through emulation, the validity of this modified genetic algorithm is proved..
A fast genetic algorithm——GSAGA(generalized self-adaptive genetic algorithm) is presented in this paper First,evenly distributed initial population is generated. Then, high quality immigrants are introduced according to the condition ofthe population schema. Finally, crossover and mutation are operated on self-adaptively in GSAGA, the searching performance and global convergence are greatly improved compared with many existing genetic algorithms. Through emulation, the validity of this modified genetic algorithm is proved..
1999, 28(1): 54-57.
Abstract:
The mechanism of local bus arbitration is different from CPU and interface chip in the GPIB-VXI controller module. This paper presents a practicable circuit on how to realize the transition of all the arbitration signals and explains this circuit in detail-Meanwhile, it also introduces the standard of TTL trigger signals in VXI bus and brings forward a realizing method in circuit.
The mechanism of local bus arbitration is different from CPU and interface chip in the GPIB-VXI controller module. This paper presents a practicable circuit on how to realize the transition of all the arbitration signals and explains this circuit in detail-Meanwhile, it also introduces the standard of TTL trigger signals in VXI bus and brings forward a realizing method in circuit.
1999, 28(1): 58-61.
Abstract:
According to the feature of the testing for gate delay faults, the testability measures of the gate delay faults are defined (the controllability and the observability of the gate delay faults in the rising or falling transition), and the method of computing these two measures are presented, which provides the quantitative criteria of design for testability of the gate delay faults.
According to the feature of the testing for gate delay faults, the testability measures of the gate delay faults are defined (the controllability and the observability of the gate delay faults in the rising or falling transition), and the method of computing these two measures are presented, which provides the quantitative criteria of design for testability of the gate delay faults.
1999, 28(1): 62-65.
Abstract:
By meas of computer simulation, the characteristics of field emission microtriodes and microtetrodes are investigates in detail. The computed results show that the emitted current and the field enhancement depend upon geometrical factors, such as tip sharpness, tip height and so on. To compare the experiment, a lot of praticable results are obtained.
By meas of computer simulation, the characteristics of field emission microtriodes and microtetrodes are investigates in detail. The computed results show that the emitted current and the field enhancement depend upon geometrical factors, such as tip sharpness, tip height and so on. To compare the experiment, a lot of praticable results are obtained.
1999, 28(1): 66-69.
Abstract:
A new transformation of modified Bessel function is built in this paper By applying the result of the theorem on the differential and integral calculus to any two equation of the type of this transformation smartly, a general integral formula involving the product of two modified Bessel functions is obtained.Furthermore, by recurrence relations of modified Bessel function, we get the analytical expressions of two kinds of integrals are gotten respectively, which can be widely used in the evaluation of the power in the electromagnetic fields.
A new transformation of modified Bessel function is built in this paper By applying the result of the theorem on the differential and integral calculus to any two equation of the type of this transformation smartly, a general integral formula involving the product of two modified Bessel functions is obtained.Furthermore, by recurrence relations of modified Bessel function, we get the analytical expressions of two kinds of integrals are gotten respectively, which can be widely used in the evaluation of the power in the electromagnetic fields.
1999, 28(1): 70-73.
Abstract:
In this paper, row distance and minimum row distance of matrix on F2 are presented, and some properties about row distance are given. Two important theorems are proved. According to these theorems, a necessary codition is obtained whether there is a maximum distance isolated code among 2-order (n,k) linear codes:n is smaller than or egual to 3(k-l) when k is bigger than or egual to 3,n is smaller than 3(k-l) when k is bigger than or egual to 5 and n can be dibided by 3.In this paper a necessary condition is also given whether there is a maximum distance isolated code among q-order (n,k) linear cedes.
In this paper, row distance and minimum row distance of matrix on F2 are presented, and some properties about row distance are given. Two important theorems are proved. According to these theorems, a necessary codition is obtained whether there is a maximum distance isolated code among 2-order (n,k) linear codes:n is smaller than or egual to 3(k-l) when k is bigger than or egual to 3,n is smaller than 3(k-l) when k is bigger than or egual to 5 and n can be dibided by 3.In this paper a necessary condition is also given whether there is a maximum distance isolated code among q-order (n,k) linear cedes.
1999, 28(1): 74-77.
Abstract:
The temporary table is a kind of specific database table which can be used to store intermediate data in the tempdb database. Using temporary table effectively can lessen the system load and promote the system executive speed in database application system. This paper introduces significance and method of creating temporary table in SYBASE database application system. The general application method of temporary table is also described. At last an example is given.
The temporary table is a kind of specific database table which can be used to store intermediate data in the tempdb database. Using temporary table effectively can lessen the system load and promote the system executive speed in database application system. This paper introduces significance and method of creating temporary table in SYBASE database application system. The general application method of temporary table is also described. At last an example is given.
1999, 28(1): 78-83.
Abstract:
In this paper,the problem of second price discrimination under the conditions of non-linear demand function is studied. The maximum conditions of monopoly revenue in the case of three stage pricing and four stage pricing are given. These new results provide a good foundion for more gener alanalysis of second degree discrimination.
In this paper,the problem of second price discrimination under the conditions of non-linear demand function is studied. The maximum conditions of monopoly revenue in the case of three stage pricing and four stage pricing are given. These new results provide a good foundion for more gener alanalysis of second degree discrimination.
1999, 28(1): 84-88.
Abstract:
The advantages of averges of forecasting relative to other combining forecasts are illustrated by an empirical study.It is pointed out that the high accuracy of fitting is not sufficient for the high accuracy of combination forecasting when the mode of economic series is highly variable.The analysis in this paper is of importance to the selection and application of combination forecasting models.
The advantages of averges of forecasting relative to other combining forecasts are illustrated by an empirical study.It is pointed out that the high accuracy of fitting is not sufficient for the high accuracy of combination forecasting when the mode of economic series is highly variable.The analysis in this paper is of importance to the selection and application of combination forecasting models.
1999, 28(1): 89-92.
Abstract:
This paper presents the deficiency of the definition method of nowadays evaluation price by analyzing the selection of the method of shadow price of the national economy evaluation. By applyzing the viewpoint ofradiating effect, the definition method of evaluation price of the goods is given in which price is controlled by the government, and which systematicly sums up the system The method of selecting the shadow price is also considered.
This paper presents the deficiency of the definition method of nowadays evaluation price by analyzing the selection of the method of shadow price of the national economy evaluation. By applyzing the viewpoint ofradiating effect, the definition method of evaluation price of the goods is given in which price is controlled by the government, and which systematicly sums up the system The method of selecting the shadow price is also considered.
1999, 28(1): 93-97.
Abstract:
This paper discusses the influence of information technology to enterprises, and the insufficiency of enterprises' MIS under the structure of traditional client/server, and analyzes the influence of Intranet to the traditional MIS architecture. Based on browser/server of Intranet, this paper proposes the following MIS architecture platforms:network application support, information resources management, office application and transaction process.
This paper discusses the influence of information technology to enterprises, and the insufficiency of enterprises' MIS under the structure of traditional client/server, and analyzes the influence of Intranet to the traditional MIS architecture. Based on browser/server of Intranet, this paper proposes the following MIS architecture platforms:network application support, information resources management, office application and transaction process.
1999, 28(1): 98-102.
Abstract:
Financial appraisal methods in the evaluation of capital projects is improtant managers to make decisions.A new model which deals with a capital investment projcet from financial, risky, and strategic point of view is developed.One of the advantages of the model is that it is simple in its calculations yet prodeuces a meaningful profile of a proposed capital investment's utility
Financial appraisal methods in the evaluation of capital projects is improtant managers to make decisions.A new model which deals with a capital investment projcet from financial, risky, and strategic point of view is developed.One of the advantages of the model is that it is simple in its calculations yet prodeuces a meaningful profile of a proposed capital investment's utility
1999, 28(1): 103-107.
Abstract:
A series of RY-2W-15k resistor is analyzed with EPMA. It is proved that the poorer the quality of insulated coat is, the poorer function it has against wet and etch. As the resistor absorbs moisture or/and eching gas, the electroconductive film of resistor is etched for electrolysis, which results in resistor disfuction.
A series of RY-2W-15k resistor is analyzed with EPMA. It is proved that the poorer the quality of insulated coat is, the poorer function it has against wet and etch. As the resistor absorbs moisture or/and eching gas, the electroconductive film of resistor is etched for electrolysis, which results in resistor disfuction.
1999, 28(1): 108-110.
Abstract:
The seal of YAG-to-glass is a key technique to develop yutrium aluminum garnet(YAG) projection tube. The seal. of YAG screen to glass cone is produced using low melting glass binder. The paper presents the material for the seal and the theories such as the match between the binder's expansion coefficient and those of YAG and glass, binder's infiltration to YAG and glass,and the binder's re-crystallization.The seal techniques including the binder cream's concoction, coating and bake are also given. The experimental results show that the seal performances are good.
The seal of YAG-to-glass is a key technique to develop yutrium aluminum garnet(YAG) projection tube. The seal. of YAG screen to glass cone is produced using low melting glass binder. The paper presents the material for the seal and the theories such as the match between the binder's expansion coefficient and those of YAG and glass, binder's infiltration to YAG and glass,and the binder's re-crystallization.The seal techniques including the binder cream's concoction, coating and bake are also given. The experimental results show that the seal performances are good.
