ISSN 
2006 Vol. 35, No. 2
2006, 35(2): 145-148.
Abstract:
Based on some established Fast Fourier Transform (FFT) spectrum correction algorithms, this paper presents an improved double-windowing method, as well as the improved extended-precision FFT scheme for fixed-point DSP. The feasibilities of the two reformative methods are discussed theoretically, and the validities are testified by the simulation results.
Based on some established Fast Fourier Transform (FFT) spectrum correction algorithms, this paper presents an improved double-windowing method, as well as the improved extended-precision FFT scheme for fixed-point DSP. The feasibilities of the two reformative methods are discussed theoretically, and the validities are testified by the simulation results.
2006, 35(2): 149-152.
Abstract:
An algorithm based on Support Vector Machines(SVM) for recognition of analogue modulation signals is presented. By analyzing the modulation signals, a set of key features for identifying different types of analogue modulation are extracted and are mapped into the high dimension space. The classification is carried out in the high dimension space based on SVM and decision tree. The result shows that all types of analogue modulation can be classified with success rate more than 90% when SNR higher than 10 dB.
An algorithm based on Support Vector Machines(SVM) for recognition of analogue modulation signals is presented. By analyzing the modulation signals, a set of key features for identifying different types of analogue modulation are extracted and are mapped into the high dimension space. The classification is carried out in the high dimension space based on SVM and decision tree. The result shows that all types of analogue modulation can be classified with success rate more than 90% when SNR higher than 10 dB.
2006, 35(2): 153-156.
Abstract:
When deliver incoming calls to users visiting their nonresident Visitor Location Register (VLR) coverage, Personal Communication Service(PCS) networks will create significant signaling and database access load. In this paper, we propose an improved cache scheme to reduce signaling cost, delivery delay and access load during calls setup. An analytical model is applied to formulate the cost of the improved scheme. Our study indicates that the proposed scheme can significantly reduce the network costs compared with the traditional call setup approach.
When deliver incoming calls to users visiting their nonresident Visitor Location Register (VLR) coverage, Personal Communication Service(PCS) networks will create significant signaling and database access load. In this paper, we propose an improved cache scheme to reduce signaling cost, delivery delay and access load during calls setup. An analytical model is applied to formulate the cost of the improved scheme. Our study indicates that the proposed scheme can significantly reduce the network costs compared with the traditional call setup approach.
2006, 35(2): 157-159.
Abstract:
In some applications, sampling with Nyquist frequency may be hard to implement due to hardware limitation. Based on subsampling, a method which estimates the modulation rate and initial frequency of the ultra-wideband LFM signal is presented in this paper. Based on the cross-spectra ESPRIT algorithm and remainder theorem, the modulation rate and initial frequency of the subsampling ultra-wideband LFM signal are estimated unambiguously and precisely even in low SNR. Simulation confirms the validity of the method.
In some applications, sampling with Nyquist frequency may be hard to implement due to hardware limitation. Based on subsampling, a method which estimates the modulation rate and initial frequency of the ultra-wideband LFM signal is presented in this paper. Based on the cross-spectra ESPRIT algorithm and remainder theorem, the modulation rate and initial frequency of the subsampling ultra-wideband LFM signal are estimated unambiguously and precisely even in low SNR. Simulation confirms the validity of the method.
2006, 35(2): 160-163.
Abstract:
The encryption system E0 in Bluetooth is generated from four LFSRs (Linear Feedback Shift Registers) by delay and combination. A new algorithm is introduced to attack E0 by using the correlation of its sequence. The average time complexities of the basic and the advance attacks respectively are O(283) and O(278). Base on the way of attacking means described in the paper, an improvement on E0 is made. In the end, some theory analysis and sample data are provided.
The encryption system E0 in Bluetooth is generated from four LFSRs (Linear Feedback Shift Registers) by delay and combination. A new algorithm is introduced to attack E0 by using the correlation of its sequence. The average time complexities of the basic and the advance attacks respectively are O(283) and O(278). Base on the way of attacking means described in the paper, an improvement on E0 is made. In the end, some theory analysis and sample data are provided.
2006, 35(2): 164-167.
Abstract:
A new application of TPC in connection with hierarchical 16QAM modulation is presented. TPC can achieve error-correcting at a high coding rate, while hierarchical modulation supports multi-services within one physical channel. The algorithms of hierarchical demodulation and iterative decoding are introduced and the performance bound of TPC in this application is theoretically analyzed. Simulations show that the SNR threshold of this scheme is very easy to fulfill in a practical digital communication system.
A new application of TPC in connection with hierarchical 16QAM modulation is presented. TPC can achieve error-correcting at a high coding rate, while hierarchical modulation supports multi-services within one physical channel. The algorithms of hierarchical demodulation and iterative decoding are introduced and the performance bound of TPC in this application is theoretically analyzed. Simulations show that the SNR threshold of this scheme is very easy to fulfill in a practical digital communication system.
2006, 35(2): 168-170,178.
Abstract:
Based on orthogonal frequency division multiplexing, this paper proposes non-coherent space-time-frequency grouping coding schemes in frequency-selective Multiple-Input and Multiple-Output(MIMO) antenna Rayleigh fading channels. Pair-wise error probability analysis show that combing subcarrier grouping with orthogonal space-time-frequency block coding, the proposed method can attain maximum spatial diversity and frequency diversity with low coding and decoding flexibility and neither the receiver nor the transmitter need knows the channel state information. The paper gives the code design criteria and simulation results, which confirm good performance of the proposed scheme in frequency-selective fading channels.
Based on orthogonal frequency division multiplexing, this paper proposes non-coherent space-time-frequency grouping coding schemes in frequency-selective Multiple-Input and Multiple-Output(MIMO) antenna Rayleigh fading channels. Pair-wise error probability analysis show that combing subcarrier grouping with orthogonal space-time-frequency block coding, the proposed method can attain maximum spatial diversity and frequency diversity with low coding and decoding flexibility and neither the receiver nor the transmitter need knows the channel state information. The paper gives the code design criteria and simulation results, which confirm good performance of the proposed scheme in frequency-selective fading channels.
2006, 35(2): 171-174.
Abstract:
Millimeter wave multibeam active phased array antenna, with broad bandwidth, high gain and controllable beams, has attracted more attention. Based on commercial devices and domestic process conditions, an active phased array scheme for geostationary satellite communication is proposed. In the scheme, direct radiation antennas and four electronically reconfigurable pencil beams are included. The phased array with 721 elements and element spacing 3 times of wavelength is presupposed to achieve 47 dB gain, 140 W output power and less than 4.5 dB noise figure.
Millimeter wave multibeam active phased array antenna, with broad bandwidth, high gain and controllable beams, has attracted more attention. Based on commercial devices and domestic process conditions, an active phased array scheme for geostationary satellite communication is proposed. In the scheme, direct radiation antennas and four electronically reconfigurable pencil beams are included. The phased array with 721 elements and element spacing 3 times of wavelength is presupposed to achieve 47 dB gain, 140 W output power and less than 4.5 dB noise figure.
2006, 35(2): 175-178.
Abstract:
It is well known that the Guard channel is an important method for the mobile communication systems, which can greatly improve the system performance by decreasing the probability of forced termination. Guard channel is hard to be adopted in the terrestrial communication system because of unpredicted traffics. We change the strategy based on the characters of LEO satellite and get a good performance. Moreover, the queuing of the new traffic has been taken to improve the performance of the whole LEO satellite communication system.
It is well known that the Guard channel is an important method for the mobile communication systems, which can greatly improve the system performance by decreasing the probability of forced termination. Guard channel is hard to be adopted in the terrestrial communication system because of unpredicted traffics. We change the strategy based on the characters of LEO satellite and get a good performance. Moreover, the queuing of the new traffic has been taken to improve the performance of the whole LEO satellite communication system.
2006, 35(2): 179-182.
Abstract:
In this paper, a fast method for parameters estimation of the multi-component linear frequency modulated (multi-LFM) signal is proposed. The proposed algorithm reduces two-dimensional searches, widely used in the time-frequency based method, FrFT and Chirp Fourier transform, into two one-dimensional searches. With utilizing the discrete FrFT along with Fast Fourier Transform (FFT) algorithm, the proposed method is a computationally fast alternative for LFM signal detection and parameters estimation. Analysis of the multi-LFM signal is performed using the Clean technique. Finally, computer simulations are provided to illustrate performances of the proposed algorithm.
In this paper, a fast method for parameters estimation of the multi-component linear frequency modulated (multi-LFM) signal is proposed. The proposed algorithm reduces two-dimensional searches, widely used in the time-frequency based method, FrFT and Chirp Fourier transform, into two one-dimensional searches. With utilizing the discrete FrFT along with Fast Fourier Transform (FFT) algorithm, the proposed method is a computationally fast alternative for LFM signal detection and parameters estimation. Analysis of the multi-LFM signal is performed using the Clean technique. Finally, computer simulations are provided to illustrate performances of the proposed algorithm.
2006, 35(2): 183-185,192.
Abstract:
Approach based on optimal cluster centers is an effective approach to radar target recognition. But its performance degrades rapidly when only a few training data are available, because badly-conditioned matrixes are generated with a few training data during the training process, and mistake appears when badly-conditioned matrixes directly participate in calculation. An improved approach based on optimal cluster centers is proposed in this paper. It solves the above problem by transforming badly-conditioned matrixes to well-conditioned matrixes, so accurate recognition results are obtained. It ensures high recognition rate when just a few training data are available. The simulation results show the efficiency of the proposed approach.
Approach based on optimal cluster centers is an effective approach to radar target recognition. But its performance degrades rapidly when only a few training data are available, because badly-conditioned matrixes are generated with a few training data during the training process, and mistake appears when badly-conditioned matrixes directly participate in calculation. An improved approach based on optimal cluster centers is proposed in this paper. It solves the above problem by transforming badly-conditioned matrixes to well-conditioned matrixes, so accurate recognition results are obtained. It ensures high recognition rate when just a few training data are available. The simulation results show the efficiency of the proposed approach.
2006, 35(2): 186-188.
Abstract:
In blind source separation, high frequency range needs a narrow sensor spacing and low frequency range needs a wide sensor spacing. The traditional methods adopt a fixed sensor spacing to separate the mixtures, so they can't get a good result. The analysis shows that the number and spacing of the sensors can effect the result of blind source separation. This paper presents a method using several separating subsystems. With this method we can get a better result.
In blind source separation, high frequency range needs a narrow sensor spacing and low frequency range needs a wide sensor spacing. The traditional methods adopt a fixed sensor spacing to separate the mixtures, so they can't get a good result. The analysis shows that the number and spacing of the sensors can effect the result of blind source separation. This paper presents a method using several separating subsystems. With this method we can get a better result.
2006, 35(2): 189-192.
Abstract:
In the process of exhaustive synthesis of thinned arrays(whose elements are thinned from the uniform grid), enumerating the configuration of linear thinned arrays is main task of design. Followed by the analyses of element spacing synthesis, two enumerate algorithms of exhaustive study on configuration of linear thinned arrays are proposed in this paper, they are recursion algorithm and binary sequence enumerate algorithm. Some comparison studies on their performance are made in order to reveal the doable relations with the thinned ratio and aperture of the arrays. The results of computer simulation show the efficiency and applicability of the algorithms respectively. Finally, their performance trials reveal the applicability when they are applied to element spacing synthesis.
In the process of exhaustive synthesis of thinned arrays(whose elements are thinned from the uniform grid), enumerating the configuration of linear thinned arrays is main task of design. Followed by the analyses of element spacing synthesis, two enumerate algorithms of exhaustive study on configuration of linear thinned arrays are proposed in this paper, they are recursion algorithm and binary sequence enumerate algorithm. Some comparison studies on their performance are made in order to reveal the doable relations with the thinned ratio and aperture of the arrays. The results of computer simulation show the efficiency and applicability of the algorithms respectively. Finally, their performance trials reveal the applicability when they are applied to element spacing synthesis.
2006, 35(2): 193-195,199.
Abstract:
It is difficult to elevate resolution higher for Synchronous Voltage-to-Frequency Converter (SVFC) since its phase modulation characteristic and the restrict of output frequency upper limit. There are some approaches to elevate its resolution higher, for example, taking the technique of integrating charge balancing and slope voltage integral. In this paper, a novel principle and implementation technology based on synchronous Pulse-Width-Modulation (SPWM) mode via dual comparators for integral is brought forward. Its basic principle is charge balancing enough within one period via integral between two reference levels, and the integral time can be fine adjusted by higher frequency synchronous clock. Moreover, charge balancing can be dynamicly adjusted within gate time by multi-periods synchronous measurement method. Verifying test indicates that its resolution is better than 5 digits, and linearity referenced to Method of Least Square better than 0.005%.
It is difficult to elevate resolution higher for Synchronous Voltage-to-Frequency Converter (SVFC) since its phase modulation characteristic and the restrict of output frequency upper limit. There are some approaches to elevate its resolution higher, for example, taking the technique of integrating charge balancing and slope voltage integral. In this paper, a novel principle and implementation technology based on synchronous Pulse-Width-Modulation (SPWM) mode via dual comparators for integral is brought forward. Its basic principle is charge balancing enough within one period via integral between two reference levels, and the integral time can be fine adjusted by higher frequency synchronous clock. Moreover, charge balancing can be dynamicly adjusted within gate time by multi-periods synchronous measurement method. Verifying test indicates that its resolution is better than 5 digits, and linearity referenced to Method of Least Square better than 0.005%.
2006, 35(2): 196-199.
Abstract:
A higher order envelope characteristic J based method is proposed in this paper for the automatic modulation recognition. The higher order envelope characteristic J has a lot of characteristics such as the computational simplicity, no demand for prior information and good performance of suppressing the noise. Therefore it can recognize the signal modulations quickly and efficiently in the lower SNR and can be implemented real-timed and practically. Simulation results indicate that the performance of proposed method is much better than the classical envelope modulation methods.
A higher order envelope characteristic J based method is proposed in this paper for the automatic modulation recognition. The higher order envelope characteristic J has a lot of characteristics such as the computational simplicity, no demand for prior information and good performance of suppressing the noise. Therefore it can recognize the signal modulations quickly and efficiently in the lower SNR and can be implemented real-timed and practically. Simulation results indicate that the performance of proposed method is much better than the classical envelope modulation methods.
2006, 35(2): 200-203.
Abstract:
This paper presents a design method for Wide-Band Signal Sampling (WBSS). Hybrid filter banks, unique clock distribution and multi phase storage are discussed for considering high precision, synchronized sampling and mass samples storage. Consequently, a design of WBSS based on above techniques is presented and its hardware prototype is realized with a 12 bit, 200 Msa/s for applications of WBSS.
This paper presents a design method for Wide-Band Signal Sampling (WBSS). Hybrid filter banks, unique clock distribution and multi phase storage are discussed for considering high precision, synchronized sampling and mass samples storage. Consequently, a design of WBSS based on above techniques is presented and its hardware prototype is realized with a 12 bit, 200 Msa/s for applications of WBSS.
2006, 35(2): 204-207.
Abstract:
This paper proposed a double stretch interpolation method based on the charge and discharge principles of the capacitors, and studied the working principles of the double stretch time measurement interpolator and its error analysis. The double stretch interpolation method is able to greatly increase the time measurement resolution and reduce the interpolation time comparing with the single stretch interpolation technique. Therefore, the conflict between the high time measurement resolution and rapid measurement speed of the single stretch interpolation method is solved efficiently.
This paper proposed a double stretch interpolation method based on the charge and discharge principles of the capacitors, and studied the working principles of the double stretch time measurement interpolator and its error analysis. The double stretch interpolation method is able to greatly increase the time measurement resolution and reduce the interpolation time comparing with the single stretch interpolation technique. Therefore, the conflict between the high time measurement resolution and rapid measurement speed of the single stretch interpolation method is solved efficiently.
2006, 35(2): 208-210,220.
Abstract:
An improved subspace method is proposed for recognizing imprecisely fragmentary faces.This method integrates non-negative matrix factorization with sparseness constraints and fisher's linear discriminant analysis subspace. Comparative experiments show that our novel subspace has recognition performance better than PCA subspace in recognizing imprecisely fragmentary faces.
An improved subspace method is proposed for recognizing imprecisely fragmentary faces.This method integrates non-negative matrix factorization with sparseness constraints and fisher's linear discriminant analysis subspace. Comparative experiments show that our novel subspace has recognition performance better than PCA subspace in recognizing imprecisely fragmentary faces.
2006, 35(2): 211-213.
Abstract:
Amelioration of Bellman-Ford algorithm is deduced in the letter based on traditional Bellman-Ford algorithm and applied to CCRP networks. The simulation results demonstrate that calculating time of networks adopted amelioration of Bellman-Ford algorithm is better than that of adopted Bellman-Ford algorithm with node number increasing and block ratio of networks is declining with request number increasing.
Amelioration of Bellman-Ford algorithm is deduced in the letter based on traditional Bellman-Ford algorithm and applied to CCRP networks. The simulation results demonstrate that calculating time of networks adopted amelioration of Bellman-Ford algorithm is better than that of adopted Bellman-Ford algorithm with node number increasing and block ratio of networks is declining with request number increasing.
2006, 35(2): 214-216.
Abstract:
The special broadcast server of TV station requires owning excellent quality and performance of broadcast. According to the (s,S) strategy, the authors propose the relation of between read buffer, multiplex buffer and program number, data velocity, disk performance, and ASI buffer. The experiment result shows that the read buffer and multiplex buffer will work better on a suitable buffer size range. Base on this result, we can optimize the server resource allocating.
The special broadcast server of TV station requires owning excellent quality and performance of broadcast. According to the (s,S) strategy, the authors propose the relation of between read buffer, multiplex buffer and program number, data velocity, disk performance, and ASI buffer. The experiment result shows that the read buffer and multiplex buffer will work better on a suitable buffer size range. Base on this result, we can optimize the server resource allocating.
2006, 35(2): 217-220.
Abstract:
Due to the variation of motor parameters and load of the AC motor vector control system, the fuzzy inference system based on the adaptive neural networks is designed to use at the speed adjustment of the AC motor vector control system. Simulation results show that the induction motor vector control system with adaptive neuro-fuzzy inference system can improve the static and dynamic performance of the motor and has good robust.
Due to the variation of motor parameters and load of the AC motor vector control system, the fuzzy inference system based on the adaptive neural networks is designed to use at the speed adjustment of the AC motor vector control system. Simulation results show that the induction motor vector control system with adaptive neuro-fuzzy inference system can improve the static and dynamic performance of the motor and has good robust.
2006, 35(2): 221-224.
Abstract:
Based on the rarefied gas dynamics theory and the squeeze film Reynolds equation amended with slip flow boundary condition, the gas film damping effect on the sensitive proof mass, moving along its axial direction, is analyzed for capacitive micro accelerometers. Simplified analysis solutions are obtained for damping force and damping coefficient. It shows that gas film damping force has relations not only with the accelerometer dimensions and velocity of the sensitive proof mass, but also with the factors, such as solid wall material, surface roughness, smooth finish, and so on. Three methods have been proposed to decrease the gas film damping of capacitive micro accelerometers through sample analysis. Finally, it is pointed out that accomodation coefficient is an key factor for gas film damping, especially for squeezed film damping.
Based on the rarefied gas dynamics theory and the squeeze film Reynolds equation amended with slip flow boundary condition, the gas film damping effect on the sensitive proof mass, moving along its axial direction, is analyzed for capacitive micro accelerometers. Simplified analysis solutions are obtained for damping force and damping coefficient. It shows that gas film damping force has relations not only with the accelerometer dimensions and velocity of the sensitive proof mass, but also with the factors, such as solid wall material, surface roughness, smooth finish, and so on. Three methods have been proposed to decrease the gas film damping of capacitive micro accelerometers through sample analysis. Finally, it is pointed out that accomodation coefficient is an key factor for gas film damping, especially for squeezed film damping.
2006, 35(2): 225-227,231.
Abstract:
The resource data storage in distributed Broad-band-service on Demand (BOD) systems is studied quantitatively. Firstly, a suitability resource placement algorithm is presented to balance the system load and to improve the system throughput. Secondly, an algorithm of replication placement policy is proposed depending on prognosticate mechanism. Applications in BOD systems approve that the algorithm can make the better access succession rate and system performance than using some other algorithms.
The resource data storage in distributed Broad-band-service on Demand (BOD) systems is studied quantitatively. Firstly, a suitability resource placement algorithm is presented to balance the system load and to improve the system throughput. Secondly, an algorithm of replication placement policy is proposed depending on prognosticate mechanism. Applications in BOD systems approve that the algorithm can make the better access succession rate and system performance than using some other algorithms.
2006, 35(2): 228-231.
Abstract:
On the basis of researching existing multicast approaches in Multiple Protocol Label Switch (MPLS), a new strategy named Aggregated and Tunnel-Based MPLS Multicast (ATMM) is proposed. ATMM merges group aggregation and tunnel technology and can alleviate limited label space, and strengthen the multicast robustness and stabilization.
On the basis of researching existing multicast approaches in Multiple Protocol Label Switch (MPLS), a new strategy named Aggregated and Tunnel-Based MPLS Multicast (ATMM) is proposed. ATMM merges group aggregation and tunnel technology and can alleviate limited label space, and strengthen the multicast robustness and stabilization.
2006, 35(2): 232-234,256.
Abstract:
There are some limitations that using genetic algorithms. This paper presents the Mixed Genetic Algorithm(MGA). Based on the phase of genetic, the colonies are differentiated to two different colonies-adaptive population and competing population. The correlated operator, propagate gene, is brought forward. The local search ability of the genetic algorithm is enhenced by using the simplex algorithm of operational research. The emulation experiment data shows the optimizing convergence reliability and higher converging velocity.
There are some limitations that using genetic algorithms. This paper presents the Mixed Genetic Algorithm(MGA). Based on the phase of genetic, the colonies are differentiated to two different colonies-adaptive population and competing population. The correlated operator, propagate gene, is brought forward. The local search ability of the genetic algorithm is enhenced by using the simplex algorithm of operational research. The emulation experiment data shows the optimizing convergence reliability and higher converging velocity.
2006, 35(2): 235-238.
Abstract:
A new intrusion detection model that based on the theory of artificial immune system is introduced in this article. It researches emphases on the arithmetic of how to get the detector that included in the negative selection arithmetic. It also puts forward a new arithmetic of how to get the detector and then analyses the arithmetic. The result indicate that, the arithmetic model can do the effective identify variation between the unknown intrusion action and the known one.
A new intrusion detection model that based on the theory of artificial immune system is introduced in this article. It researches emphases on the arithmetic of how to get the detector that included in the negative selection arithmetic. It also puts forward a new arithmetic of how to get the detector and then analyses the arithmetic. The result indicate that, the arithmetic model can do the effective identify variation between the unknown intrusion action and the known one.
2006, 35(2): 239-241.
Abstract:
The concept, characteristics, application fields of wireless sensors network are briefly introduced. Application of wireless sensors network in voice source location is presented in detail and the principle and deduction of the locating algorithm in two dimensional space are discussed. Open issues and development intends of sensors network are also discussed.
The concept, characteristics, application fields of wireless sensors network are briefly introduced. Application of wireless sensors network in voice source location is presented in detail and the principle and deduction of the locating algorithm in two dimensional space are discussed. Open issues and development intends of sensors network are also discussed.
2006, 35(2): 242-245.
Abstract:
Principle and method of correcting nonlinear error of sensors based on the support vector machine is given. The algorithm can identify and know the contrary model characteristic of sensor correctly only according to the sample, having no use for any priori knowledge about contrary model function. It also convert original problem into protruding quadratic optimizing of question. The algorithm can ensure that extreme solution is optimal and have ability of common. In the end, through using in application of wet-capacitance sensor error correction, the algorithm can make better result.
Principle and method of correcting nonlinear error of sensors based on the support vector machine is given. The algorithm can identify and know the contrary model characteristic of sensor correctly only according to the sample, having no use for any priori knowledge about contrary model function. It also convert original problem into protruding quadratic optimizing of question. The algorithm can ensure that extreme solution is optimal and have ability of common. In the end, through using in application of wet-capacitance sensor error correction, the algorithm can make better result.
2006, 35(2): 246-248.
Abstract:
The variation of magnetic properties with new Rapid Recurrent Thermal Annealing (RRTA) has been studied in high moment thin film (Co0.35Fe0.65)99O1. After the rapid recurrent thermal annealing the coercivity as-deposited this thin film decreases from 105 to 3 Oe at 450℃ for several periods of times, their resistivity decreases to 70%, and the size of a-Fe(Co)phase can be reduced to 15~35 nm by analysis. Results show that the method is more effective than other methods to improve the magnetic and electrical properties of (Co0.35Fe0.65)99O1 thin films.
The variation of magnetic properties with new Rapid Recurrent Thermal Annealing (RRTA) has been studied in high moment thin film (Co0.35Fe0.65)99O1. After the rapid recurrent thermal annealing the coercivity as-deposited this thin film decreases from 105 to 3 Oe at 450℃ for several periods of times, their resistivity decreases to 70%, and the size of a-Fe(Co)phase can be reduced to 15~35 nm by analysis. Results show that the method is more effective than other methods to improve the magnetic and electrical properties of (Co0.35Fe0.65)99O1 thin films.
2006, 35(2): 249-252.
Abstract:
In order to measuring photocurrent-voltage characteristics, sandwich-type cells were fabricated by the vacuum evaporation technique. The cells were investigated recording in situ current-voltage(I-V) characteristics and photoelectric sensitivity. The obtained charge intensification effect of DiMe-PTCDI under a bias voltage of 17 V is 103 times. Furthermore, the photocurrent-voltage characteristics obey fowler-nordheim equation, which indicates charge intensification effect by tunneling injection process.
In order to measuring photocurrent-voltage characteristics, sandwich-type cells were fabricated by the vacuum evaporation technique. The cells were investigated recording in situ current-voltage(I-V) characteristics and photoelectric sensitivity. The obtained charge intensification effect of DiMe-PTCDI under a bias voltage of 17 V is 103 times. Furthermore, the photocurrent-voltage characteristics obey fowler-nordheim equation, which indicates charge intensification effect by tunneling injection process.
2006, 35(2): 253-256.
Abstract:
ZnO:Al (ZAO) thin films with different proportion of Al3+ doping are prepared by sol-gel method. XRD, AFM, ultraviolet-visible spectroscope meter and the method of four-explorwtion-needle are adopted to test the property of ZAO thin films. Through analysis and comparison, hereinafter phenomena can be obtained:ZAO thin films prepared by sol-gel method has polycrystalline hexagonal wurtzite structure, the surface of the ZAO thin films is flat, the crystal is very thickness and symmetry. The conductivity can be improved by Al3+ doping. The transmittance in ultraviolet-visible region is higher than 80% with hypo-Al3+ doping, accompanying the phenomena of Burstein moving. The transmittance increases indistinctively, but the phenomena of burstein moving is aggravating, the most amount of Burstein moving measure up to 340 nm.
ZnO:Al (ZAO) thin films with different proportion of Al3+ doping are prepared by sol-gel method. XRD, AFM, ultraviolet-visible spectroscope meter and the method of four-explorwtion-needle are adopted to test the property of ZAO thin films. Through analysis and comparison, hereinafter phenomena can be obtained:ZAO thin films prepared by sol-gel method has polycrystalline hexagonal wurtzite structure, the surface of the ZAO thin films is flat, the crystal is very thickness and symmetry. The conductivity can be improved by Al3+ doping. The transmittance in ultraviolet-visible region is higher than 80% with hypo-Al3+ doping, accompanying the phenomena of Burstein moving. The transmittance increases indistinctively, but the phenomena of burstein moving is aggravating, the most amount of Burstein moving measure up to 340 nm.
2006, 35(2): 257-260.
Abstract:
In this paper, comparison of coupling crosstalk between parallel striplines with and without via fences structure, and different via fences structures when striplines's pacing changing are presented numerically and emulationally. In addition, the relation between via holes diameter and return loss is emonstrated. Finally, a new via fences structure, which significantly reduces coupling crosstalk and improves return loss, is introduced.
In this paper, comparison of coupling crosstalk between parallel striplines with and without via fences structure, and different via fences structures when striplines's pacing changing are presented numerically and emulationally. In addition, the relation between via holes diameter and return loss is emonstrated. Finally, a new via fences structure, which significantly reduces coupling crosstalk and improves return loss, is introduced.
2006, 35(2): 261-263.
Abstract:
Low resistivity Indium Tin Oxide (ITO) films were deposited by DC magnetron sputtering using ITO targets. Films deposited at substrate temperature of 250℃ with 200 W input DC power, in an oxygen/argon atmosphere, argon flow was kept at about 16 sccm and the oxygen flow was less than 1sccm, respectively. Annealing of the ITO films without oxygen for 1 h was necessary for achieving low resistivities. Low resistivity (80%) in visible region were found to occur at a high annealing temperature about 350℃.
Low resistivity Indium Tin Oxide (ITO) films were deposited by DC magnetron sputtering using ITO targets. Films deposited at substrate temperature of 250℃ with 200 W input DC power, in an oxygen/argon atmosphere, argon flow was kept at about 16 sccm and the oxygen flow was less than 1sccm, respectively. Annealing of the ITO films without oxygen for 1 h was necessary for achieving low resistivities. Low resistivity (80%) in visible region were found to occur at a high annealing temperature about 350℃.
2006, 35(2): 264-267.
Abstract:
An AC-voltage driving circuit is proposed and designed. Meanwhile the test of the circuit and the characteristic of Organic Light-Emitling Device(OLED) under AC-voltage driving are studied. The relevant test and research show that the AC-driving circuit functions excellently, realizing AC driving and restraining the cross talk, and the lifetime of OLED can be improved greatly. Under the research of characteristic of AC driving, we find the performance of OLED's pixel is largely impacted by driving frequency and the frequency of 50 Hz is fit for OLED most.
An AC-voltage driving circuit is proposed and designed. Meanwhile the test of the circuit and the characteristic of Organic Light-Emitling Device(OLED) under AC-voltage driving are studied. The relevant test and research show that the AC-driving circuit functions excellently, realizing AC driving and restraining the cross talk, and the lifetime of OLED can be improved greatly. Under the research of characteristic of AC driving, we find the performance of OLED's pixel is largely impacted by driving frequency and the frequency of 50 Hz is fit for OLED most.
2006, 35(2): 268-270.
Abstract:
The wide diameter is an new graph parameter which can measure fault tolerance and transmission delay of a parallel processing computer network at the same time. The generalized Hypercube is an important network topology for parallel processing computer system. In this paper, the wide-diameter of generalized hypercube is proved in two ways whose difference is to use mathematical induction and constructing method to prove the inequation (1).
The wide diameter is an new graph parameter which can measure fault tolerance and transmission delay of a parallel processing computer network at the same time. The generalized Hypercube is an important network topology for parallel processing computer system. In this paper, the wide-diameter of generalized hypercube is proved in two ways whose difference is to use mathematical induction and constructing method to prove the inequation (1).
2006, 35(2): 271-274.
Abstract:
Queue system with vacations is an important model of queue theory. In this article we study M/G/1 queue system during vacations the arriver enter system with probability p. Using the method of L-S transformation and generated function, we Get the expression formulaion of delaying time and the distributing generated function of waiting time.
Queue system with vacations is an important model of queue theory. In this article we study M/G/1 queue system during vacations the arriver enter system with probability p. Using the method of L-S transformation and generated function, we Get the expression formulaion of delaying time and the distributing generated function of waiting time.
2006, 35(2): 275-278.
Abstract:
Under the entire entry deregulation, a two-stage model of entrant decision is established. Researching the entrant decision by utilizing the real-option approach, the entry decision rules with flexibility are given. The result shows that the entrant's entry is decided by the comparative relationship between the market demand and the threshold, and the value of threshold depends on the entry cost and the scale of the incumbent. Therefore, the entire entry deregulation not only optimizes the telecommunication industry competition status, but also promotes the telecommunication industry technology.
Under the entire entry deregulation, a two-stage model of entrant decision is established. Researching the entrant decision by utilizing the real-option approach, the entry decision rules with flexibility are given. The result shows that the entrant's entry is decided by the comparative relationship between the market demand and the threshold, and the value of threshold depends on the entry cost and the scale of the incumbent. Therefore, the entire entry deregulation not only optimizes the telecommunication industry competition status, but also promotes the telecommunication industry technology.
2006, 35(2): 279-281.
Abstract:
This paper analyzes the impact of return policies on the wholesale price,retail price, profit of manufacturer, and retailer. After discussion for uncertainty demands, some conclusions and critical conditions are presented and therefore proved. This provide the more efficient academic proof for return policies selection.
This paper analyzes the impact of return policies on the wholesale price,retail price, profit of manufacturer, and retailer. After discussion for uncertainty demands, some conclusions and critical conditions are presented and therefore proved. This provide the more efficient academic proof for return policies selection.
2006, 35(2): 282-284.
Abstract:
The classical Kyle model to the infinite horizon case is generalized. Based on this, The trading strategy of informed trader in the sense of linear equilibrium. Based on assumption that private information is disclosed to the market gradually. Compared with classical Kyle model, informed trader has less trading enthusiasm, and has more expected profits due to more information advantage.
The classical Kyle model to the infinite horizon case is generalized. Based on this, The trading strategy of informed trader in the sense of linear equilibrium. Based on assumption that private information is disclosed to the market gradually. Compared with classical Kyle model, informed trader has less trading enthusiasm, and has more expected profits due to more information advantage.
2006, 35(2): 285-288.
Abstract:
As a source of innovation in our country, university and college in China plays a very important role in enforcement of self intellectual property rights. From the perspective of patent application, the paper by using explores the relationship between the total volume of patent application of university and college in China and time experimental research methods, A forecasting about variation of patent application of university and college in China in coming few years is given.
As a source of innovation in our country, university and college in China plays a very important role in enforcement of self intellectual property rights. From the perspective of patent application, the paper by using explores the relationship between the total volume of patent application of university and college in China and time experimental research methods, A forecasting about variation of patent application of university and college in China in coming few years is given.
