ISSN 
2006 Vol. 35, No. 6
2006, 35(6): 861-864.
Abstract:
In Additive White Gaussian Noise (AWGN) channel, we introduce a method for synchronization of symbol timing and frequency for two-dimensional spread spectrum system without prior knowledge of spread spectrum matrix. Based on the periodical characteristic of the two-dimensional spread spectrum matrix, the method estimates the frequency offset, and then synchronizes the symbol timing by moving the position of data-storage window to calculate the maximum eigenvalue of correlation matrix. Computer simulations demonstrate the efficiency of this method.
In Additive White Gaussian Noise (AWGN) channel, we introduce a method for synchronization of symbol timing and frequency for two-dimensional spread spectrum system without prior knowledge of spread spectrum matrix. Based on the periodical characteristic of the two-dimensional spread spectrum matrix, the method estimates the frequency offset, and then synchronizes the symbol timing by moving the position of data-storage window to calculate the maximum eigenvalue of correlation matrix. Computer simulations demonstrate the efficiency of this method.
2006, 35(6): 865-868.
Abstract:
Aimed at PCM/FM reentry remote sensing systems existed in multipath-Induced, the characteristic of amplitude, phase, group delay of the two-path model is analyzed based on presenting some typical theoretical models of reentry remote sensing transmission channel. And the effects on receiver (which are cause by the change of amplitude distortion), group delay distortion, bit rate and channel attenuation factor are analyzed by using two-path model. Delay distortion can cause large amplitude variance of receiving signal. And the joint action between delay distortion and channel attenuation factor influences receiver's performance boundary. Increasing bit rate alone directly leads to worse capacity parameters of the system. The simulation results give references to design reentry remote sensing system rationally in engineering application.
Aimed at PCM/FM reentry remote sensing systems existed in multipath-Induced, the characteristic of amplitude, phase, group delay of the two-path model is analyzed based on presenting some typical theoretical models of reentry remote sensing transmission channel. And the effects on receiver (which are cause by the change of amplitude distortion), group delay distortion, bit rate and channel attenuation factor are analyzed by using two-path model. Delay distortion can cause large amplitude variance of receiving signal. And the joint action between delay distortion and channel attenuation factor influences receiver's performance boundary. Increasing bit rate alone directly leads to worse capacity parameters of the system. The simulation results give references to design reentry remote sensing system rationally in engineering application.
2006, 35(6): 869-871,878.
Abstract:
This paper proposes an all-optical node which can regenerate the optical packet using the SCM label. The node has a simple structure and do not need wavelength conversion. The node can regenerate the SCM label and payload simultaneously. The simulation result demonstrates that the node can stabilize the spectrum of SCM label and payload, and suppress the crosstalk and regenerate the signal obviously.
This paper proposes an all-optical node which can regenerate the optical packet using the SCM label. The node has a simple structure and do not need wavelength conversion. The node can regenerate the SCM label and payload simultaneously. The simulation result demonstrates that the node can stabilize the spectrum of SCM label and payload, and suppress the crosstalk and regenerate the signal obviously.
2006, 35(6): 872-875.
Abstract:
The error probability performance for MIMO WCDMA systems with the space-time block codes and convolutional codes employed at the transmitter, maximal-ratio-combining antenna diversity and soft decoding schemes employed at the receiver is investigated under the condition of multiple access interference. Based on the alternative representations of Q(x) and the moment generating function of SINR, the pairwise error probability of a convolutional coded system and union upper bound of error performance are derived under the condition of multiple access interference and nonidentical average transmitted power at each transmit antenna in Nakagami-m fading channels.The performance of a space-path diversity receiver in various coding schemes is illustrated. Numerical results show that the combination of convolutional coding and spatial combining leads to a dramatic performance improvement for MIMO WCDMA systems. The analysis result can be applied to uplink and downlink of MIMO WCDMA systems.
The error probability performance for MIMO WCDMA systems with the space-time block codes and convolutional codes employed at the transmitter, maximal-ratio-combining antenna diversity and soft decoding schemes employed at the receiver is investigated under the condition of multiple access interference. Based on the alternative representations of Q(x) and the moment generating function of SINR, the pairwise error probability of a convolutional coded system and union upper bound of error performance are derived under the condition of multiple access interference and nonidentical average transmitted power at each transmit antenna in Nakagami-m fading channels.The performance of a space-path diversity receiver in various coding schemes is illustrated. Numerical results show that the combination of convolutional coding and spatial combining leads to a dramatic performance improvement for MIMO WCDMA systems. The analysis result can be applied to uplink and downlink of MIMO WCDMA systems.
2006, 35(6): 876-878.
Abstract:
Image denoising method based on image sparse decomposition is different from the traditional image denoising methods. In this method, image corrupted by noise is decomposed into two parts. One part is the image sparse components which are related to image information. Another part, which remains after the image sparse components are subtracted from the image, is regarded as noise. Image can be denoised by reconstructing image only with its sparse components. Experimental results show the good performance of this method.
Image denoising method based on image sparse decomposition is different from the traditional image denoising methods. In this method, image corrupted by noise is decomposed into two parts. One part is the image sparse components which are related to image information. Another part, which remains after the image sparse components are subtracted from the image, is regarded as noise. Image can be denoised by reconstructing image only with its sparse components. Experimental results show the good performance of this method.
2006, 35(6): 879-882.
Abstract:
Based on the Parks-McClellan algorithm, this paper introduces a pulse shape design for UWB wave. The wave obtained by this method can optimally utilize the bandwidth by the FCC spectral mask. The result is suitable for both single band or multi-band UWB system.
Based on the Parks-McClellan algorithm, this paper introduces a pulse shape design for UWB wave. The wave obtained by this method can optimally utilize the bandwidth by the FCC spectral mask. The result is suitable for both single band or multi-band UWB system.
2006, 35(6): 883-886.
Abstract:
Power management is an important technique to prolong the lifetime of battery-powered wireless Ad Hoc networks. This paper analyzes the Power Saving Mechanism (PSM) of IEEE 802.11 Distributed Coordination Function (DCF) and presents a self-adaptive power saving mechanism, which consists of three different beacon intervals. In the new scheme the node selects one of the three beacon intervals dynamically, depending on its traffic. Simulation results show that the new scheme not only improves the efficiency of energy greatly but also achieves desirable transmission delay and throughput.
Power management is an important technique to prolong the lifetime of battery-powered wireless Ad Hoc networks. This paper analyzes the Power Saving Mechanism (PSM) of IEEE 802.11 Distributed Coordination Function (DCF) and presents a self-adaptive power saving mechanism, which consists of three different beacon intervals. In the new scheme the node selects one of the three beacon intervals dynamically, depending on its traffic. Simulation results show that the new scheme not only improves the efficiency of energy greatly but also achieves desirable transmission delay and throughput.
2006, 35(6): 887-889.
Abstract:
In this paper, the role of the extend interframe spaces in IEEE 802.11 DCF is analyzed, and the potential unfairness problem is illustrated using the DCF in Ad Hoc network. A simple improved scheme, MDCF, is provided. Simulations prove that MDCF can improve the unfairness problem well.
In this paper, the role of the extend interframe spaces in IEEE 802.11 DCF is analyzed, and the potential unfairness problem is illustrated using the DCF in Ad Hoc network. A simple improved scheme, MDCF, is provided. Simulations prove that MDCF can improve the unfairness problem well.
2006, 35(6): 890-893.
Abstract:
A new non-line-of-sight location algorithm based on TDOA for mobile station is developed in this paper. One of the advantages of this method is that no statistical models or prior information on NLOS channel condition are needed. Simulation and comparison of performance with other existing methods have shown the effectiveness of NLOS error mitigation in location estimate. Its good characteristics including low requirement, non-iteration, very low computational complexity make it easily available to apply to practice.
A new non-line-of-sight location algorithm based on TDOA for mobile station is developed in this paper. One of the advantages of this method is that no statistical models or prior information on NLOS channel condition are needed. Simulation and comparison of performance with other existing methods have shown the effectiveness of NLOS error mitigation in location estimate. Its good characteristics including low requirement, non-iteration, very low computational complexity make it easily available to apply to practice.
2006, 35(6): 894-896,912.
Abstract:
A new dynamic multitarget track initiation algorithm for two direction-finding location systems was presented:a part of false intersection points were first eliminated by some heuristic rules, then all straight tracks were detected by Hough transform, and the true tracks were finally initiated by logic-based methods. Its high efficiency is confirmed by simulations in real complex environment where exist false alarms, missed detections and an unknown number of targets. At the end, the method of extending the presented algorithm from two-observation systems to multi-observation systems was introduced and then the NP-complete problem of associating measurements from multiple passive sensors is avoided.
A new dynamic multitarget track initiation algorithm for two direction-finding location systems was presented:a part of false intersection points were first eliminated by some heuristic rules, then all straight tracks were detected by Hough transform, and the true tracks were finally initiated by logic-based methods. Its high efficiency is confirmed by simulations in real complex environment where exist false alarms, missed detections and an unknown number of targets. At the end, the method of extending the presented algorithm from two-observation systems to multi-observation systems was introduced and then the NP-complete problem of associating measurements from multiple passive sensors is avoided.
2006, 35(6): 897-900.
Abstract:
The existence of spatial correlation will severely degrade the performance of MIMO systems, we propose an algorithm called Space Time Robust to Correlated MIMO (STRCM) that Alamouti's code is utilized to obtain the transmit diversity, V-BLAST order interference cancellation detection is adopted in the receiver directly via the grouping and reconstruction of channel matrix. Simulations show that the proposed scheme is more robust to spatial correlation than V-BLAST, and the complexity is not increase.
The existence of spatial correlation will severely degrade the performance of MIMO systems, we propose an algorithm called Space Time Robust to Correlated MIMO (STRCM) that Alamouti's code is utilized to obtain the transmit diversity, V-BLAST order interference cancellation detection is adopted in the receiver directly via the grouping and reconstruction of channel matrix. Simulations show that the proposed scheme is more robust to spatial correlation than V-BLAST, and the complexity is not increase.
2006, 35(6): 901-904.
Abstract:
A novel data transfer system is proposed for surveillance & measure management office and the performance of the system has been analyzed. In this system, more routs are selected by dummy repeater technique. An application of the method has testified that the system has some good characters, such as lower cost, easily implemented, and better practicability.
A novel data transfer system is proposed for surveillance & measure management office and the performance of the system has been analyzed. In this system, more routs are selected by dummy repeater technique. An application of the method has testified that the system has some good characters, such as lower cost, easily implemented, and better practicability.
2006, 35(6): 905-908.
Abstract:
Firstly, the model about space geometry layout of bi-static SAR system is given, its range history and range change rate history are analyzed as well. Comparison of the result to the mono-static SAR demonstrates its specialty and complexity. Lastly, the point target signal of bi-static SAR system is analyzed, and its phase variation history and its character are derived, which provide the theory reference for the signal processing research of bi-static SAR system.
Firstly, the model about space geometry layout of bi-static SAR system is given, its range history and range change rate history are analyzed as well. Comparison of the result to the mono-static SAR demonstrates its specialty and complexity. Lastly, the point target signal of bi-static SAR system is analyzed, and its phase variation history and its character are derived, which provide the theory reference for the signal processing research of bi-static SAR system.
2006, 35(6): 909-912.
Abstract:
According to transmission line theory and distributed parameter theory, it is pointed out that the sampling waveforms distortion is produced by multi-capacitance loading of fast-pulse transmission line. The equivalent distributed capacitance compensation model is proposed, the two matching computing methods and formulas are given. The results of numerical computation show that pulse transmission line of multi-small-loading capacitance with proportional spacing can be well compensated by the equivalent distributed capacitance method.
According to transmission line theory and distributed parameter theory, it is pointed out that the sampling waveforms distortion is produced by multi-capacitance loading of fast-pulse transmission line. The equivalent distributed capacitance compensation model is proposed, the two matching computing methods and formulas are given. The results of numerical computation show that pulse transmission line of multi-small-loading capacitance with proportional spacing can be well compensated by the equivalent distributed capacitance method.
2006, 35(6): 913-916.
Abstract:
A speed analysis methodology for a switched-capacitor pipelined A/D converter is presented. The conversion speed of a pipelined A/D converter is determined by the settling speed of the switched-capacitor feedback amplifier in the conversion stage. According to the principle of the pipelined architecture, the formula of the equivalent input step voltage seen at the input nodes of the op-amp is obtained. Then by dividing the settling phase into the large-signal and small-signal mode and using different op-amp model in the different mode, the expression which shows the relationship between the settling time and circuit parameters such as the value of sampling capacitors or op-amp specifications is obtained. Finally, the proposed methodology and the obtained expression are verified by the MATLAB simulation on a 10-bit pipelined ADC.
A speed analysis methodology for a switched-capacitor pipelined A/D converter is presented. The conversion speed of a pipelined A/D converter is determined by the settling speed of the switched-capacitor feedback amplifier in the conversion stage. According to the principle of the pipelined architecture, the formula of the equivalent input step voltage seen at the input nodes of the op-amp is obtained. Then by dividing the settling phase into the large-signal and small-signal mode and using different op-amp model in the different mode, the expression which shows the relationship between the settling time and circuit parameters such as the value of sampling capacitors or op-amp specifications is obtained. Finally, the proposed methodology and the obtained expression are verified by the MATLAB simulation on a 10-bit pipelined ADC.
2006, 35(6): 917-919,923.
Abstract:
This paper provides a quantum key distribution protocol based on the correlations of Einstein-Podolsky-Rosen (EPR) pairs. The two parties establish the key by exchanging qubits and performing the Bell state measurement. This protocol is proved to be secure because that no other people can get the key without being found. All qubits distribute to the key except those for error-checking. So the protocol is efficient.
This paper provides a quantum key distribution protocol based on the correlations of Einstein-Podolsky-Rosen (EPR) pairs. The two parties establish the key by exchanging qubits and performing the Bell state measurement. This protocol is proved to be secure because that no other people can get the key without being found. All qubits distribute to the key except those for error-checking. So the protocol is efficient.
2006, 35(6): 920-923.
Abstract:
This paper introduces JPEG2000 encode and decode flow, and also the principle of JPEG2000 arithmetic coding. Traditional arithmetic decoder is very slow that may be the bottleneck of the JPEG2000 system. To solve this problem, a pipeline arithmetic decoder is present here, together with the hardware chart. The arithmetic decoder is verified with FPGA and is implemented in TSMC 0.25 μm technology.
This paper introduces JPEG2000 encode and decode flow, and also the principle of JPEG2000 arithmetic coding. Traditional arithmetic decoder is very slow that may be the bottleneck of the JPEG2000 system. To solve this problem, a pipeline arithmetic decoder is present here, together with the hardware chart. The arithmetic decoder is verified with FPGA and is implemented in TSMC 0.25 μm technology.
2006, 35(6): 924-927.
Abstract:
This paper gives an auto-restorable fragile watermarking algorithm for image content authentication, which can not only detect the location of any changes in images but also restore the altered image content. Firstly, the low frequents sector picked up by discrete wavelet transform(DWT) as watermarking. Then the RS correct-encode technology is used to encode the watermarking. Finally, the watermarking data are embed into the lowest bits of the image data after being changed with arnold shuffling techniques and chaotic encrypt tentechniques. Experimental results demonstrate that the watermarking algorithm is a valid fragile digital image watermarking algorithm.
This paper gives an auto-restorable fragile watermarking algorithm for image content authentication, which can not only detect the location of any changes in images but also restore the altered image content. Firstly, the low frequents sector picked up by discrete wavelet transform(DWT) as watermarking. Then the RS correct-encode technology is used to encode the watermarking. Finally, the watermarking data are embed into the lowest bits of the image data after being changed with arnold shuffling techniques and chaotic encrypt tentechniques. Experimental results demonstrate that the watermarking algorithm is a valid fragile digital image watermarking algorithm.
2006, 35(6): 928-931.
Abstract:
Analyzing error characters of inertial sensors and modeling errors are important tasks when building Inertial Navigation Systems (INS) and effective ways to improve accuracy of INS. Non-stochastic error characters and error sources of a typical kind of MEMS gyroscope in structures and Comb-drive Tuning Fork Gyroscope (TFG) are researched. The effects of interfering torques are discussed from the aspect of two-order weakly damped control systems. The open-loop sensitivity of the gyroscope is focused on and its variation versus temperature, specific force and angle rate is brought forward to under some simplified conditions. Finally, the form of the non-stochastic error model is concluded and the conclusion is much helpful and instructional to modeling non-stochastic errors of TFG.
Analyzing error characters of inertial sensors and modeling errors are important tasks when building Inertial Navigation Systems (INS) and effective ways to improve accuracy of INS. Non-stochastic error characters and error sources of a typical kind of MEMS gyroscope in structures and Comb-drive Tuning Fork Gyroscope (TFG) are researched. The effects of interfering torques are discussed from the aspect of two-order weakly damped control systems. The open-loop sensitivity of the gyroscope is focused on and its variation versus temperature, specific force and angle rate is brought forward to under some simplified conditions. Finally, the form of the non-stochastic error model is concluded and the conclusion is much helpful and instructional to modeling non-stochastic errors of TFG.
2006, 35(6): 932-935.
Abstract:
Taking the advantage of two methods to fuze, this paper proposes a self-adaptive penetrating fuze algorithm which is more flexible and practical. By this method, the burst point control is completed by ‘calculating the depth of the penetrating’ and ‘identifying the complicate medium’. Furthermore the hardware scheme of fuze system is also presented under the Micro-system, utilizing the high-g array accelerometer fabricated by MEMS as the key parts of the fuze and in virtue of the programmable logic device technology. This fuze system can adapt to the complicated battle circumstance and satisfy real-time requirement.
Taking the advantage of two methods to fuze, this paper proposes a self-adaptive penetrating fuze algorithm which is more flexible and practical. By this method, the burst point control is completed by ‘calculating the depth of the penetrating’ and ‘identifying the complicate medium’. Furthermore the hardware scheme of fuze system is also presented under the Micro-system, utilizing the high-g array accelerometer fabricated by MEMS as the key parts of the fuze and in virtue of the programmable logic device technology. This fuze system can adapt to the complicated battle circumstance and satisfy real-time requirement.
2006, 35(6): 936-938.
Abstract:
In this paper, NiCr alloy was vaporized on the silicon in vacuum as the catalyzer and synthesized Carbon NanoTubes (CNTs) film using chemical vapour deposition. We treated CNTs film with H2 plasma and measured the field emission characteristic of CNTs film. CNTs film's turn on fields was 1~1.2 V/μm and had obviously reduced compared with that not treated. The most field emission current was increased 34 μA from 12.3 μA after annealed.
In this paper, NiCr alloy was vaporized on the silicon in vacuum as the catalyzer and synthesized Carbon NanoTubes (CNTs) film using chemical vapour deposition. We treated CNTs film with H2 plasma and measured the field emission characteristic of CNTs film. CNTs film's turn on fields was 1~1.2 V/μm and had obviously reduced compared with that not treated. The most field emission current was increased 34 μA from 12.3 μA after annealed.
2006, 35(6): 939-941.
Abstract:
The analytical solution to the Frounhofer diffraction of Gaussian beam by a circular aperture is inferred and is compared with the result from the parallel beam. Due to the results of the numerical computation, the distributing curves of light intensity are drawn in the two instances. After the comparison between of the two curves, a conclusion is drawn that when the circle aperture radius a2ww0 the result of Gaussian beam's Frounhofer diffraction is approximate to parallel beam's Frounhofer diffraction. The difference is produced because of ignoring the terms with high degree which n ≥ 2 in the analytics solution.
The analytical solution to the Frounhofer diffraction of Gaussian beam by a circular aperture is inferred and is compared with the result from the parallel beam. Due to the results of the numerical computation, the distributing curves of light intensity are drawn in the two instances. After the comparison between of the two curves, a conclusion is drawn that when the circle aperture radius a2ww0 the result of Gaussian beam's Frounhofer diffraction is approximate to parallel beam's Frounhofer diffraction. The difference is produced because of ignoring the terms with high degree which n ≥ 2 in the analytics solution.
2006, 35(6): 942-945.
Abstract:
For the large torque ripple of inductance motor based on direct torque control, especially at a low speed, this paper proposes a new control strategy. On the basis of improving conventional switch table of direct torque control system, a two-hysterics control switch table is established in the strategy in order to decrease torque ripple. The simulation shows that it can get good torque performance.
For the large torque ripple of inductance motor based on direct torque control, especially at a low speed, this paper proposes a new control strategy. On the basis of improving conventional switch table of direct torque control system, a two-hysterics control switch table is established in the strategy in order to decrease torque ripple. The simulation shows that it can get good torque performance.
2006, 35(6): 946-949.
Abstract:
Based on the analysis of the algorithms commonly used for task assignment, this paper puts forward an improved both-initiated adaptive algorithm for task assignment. This algorithm adaptively determines initiated strategy according to the system load. In the system, the data requirement of each task and the data distribution are considered.The nodes are effectively chosen so as to minimize the costs for task assignment. This algorithm has been successfully applied in distributed parallel database system DPSQL. It has been shown that the method has better efficiency and stability than the common algorithms for task assignment.
Based on the analysis of the algorithms commonly used for task assignment, this paper puts forward an improved both-initiated adaptive algorithm for task assignment. This algorithm adaptively determines initiated strategy according to the system load. In the system, the data requirement of each task and the data distribution are considered.The nodes are effectively chosen so as to minimize the costs for task assignment. This algorithm has been successfully applied in distributed parallel database system DPSQL. It has been shown that the method has better efficiency and stability than the common algorithms for task assignment.
2006, 35(6): 950-952.
Abstract:
This article analyzes the traditional access control models, points out their defects and existing problems. Particularly, a role-based access control model and its merits are introduced in this article. And then, the advanced methods of reconstructing the traditional BLP models with role-based access control model is proposed and a brief theoretical analysis is given.
This article analyzes the traditional access control models, points out their defects and existing problems. Particularly, a role-based access control model and its merits are introduced in this article. And then, the advanced methods of reconstructing the traditional BLP models with role-based access control model is proposed and a brief theoretical analysis is given.
2006, 35(6): 953-955,959.
Abstract:
There are some questions in Internet-based Distance Teaching (IDT) at present, such as how to gain exact information from large masses of feedback data, how to provide customized web learning environment, how to implement automated question answering system, etc. This article presents how to apply data mining technology to resolve these questions and gives a model for it. Our research shows data mining technology can resolve some questions in IDT.
There are some questions in Internet-based Distance Teaching (IDT) at present, such as how to gain exact information from large masses of feedback data, how to provide customized web learning environment, how to implement automated question answering system, etc. This article presents how to apply data mining technology to resolve these questions and gives a model for it. Our research shows data mining technology can resolve some questions in IDT.
2006, 35(6): 956-959.
Abstract:
In example based machine translation, sentence similarity computing is an effective mechanism for example matching. Aiming at a sentence similarity model based on same words, an improved method is put forward, including the extraction of keywords, and the induction of synonyms in sentence similarity definition. Experiment result shows that the improved method has better accuracy than the former.
In example based machine translation, sentence similarity computing is an effective mechanism for example matching. Aiming at a sentence similarity model based on same words, an improved method is put forward, including the extraction of keywords, and the induction of synonyms in sentence similarity definition. Experiment result shows that the improved method has better accuracy than the former.
2006, 35(6): 960-963.
Abstract:
The nanocrystalline nickel oxide was prepared by a citrate-gel method.The results showed that the NiOx prepared in the optimum condition (CA:Ni2+ mole ratio 1.3:1.0,annealing at 400℃ for 1h).The electrochemical capacitive behaviors of the NiOx electrodes were characterized by Cyclic Voltammetry (CV),chronopotentiometry (CP) and A.C.impedance in 1 mol/L KOH aqueous solution.The electrochemical measurements indicated that the prepared samples exhibited high specific capacitance of 78.74 F/g,and excellent cyclability.
The nanocrystalline nickel oxide was prepared by a citrate-gel method.The results showed that the NiOx prepared in the optimum condition (CA:Ni2+ mole ratio 1.3:1.0,annealing at 400℃ for 1h).The electrochemical capacitive behaviors of the NiOx electrodes were characterized by Cyclic Voltammetry (CV),chronopotentiometry (CP) and A.C.impedance in 1 mol/L KOH aqueous solution.The electrochemical measurements indicated that the prepared samples exhibited high specific capacitance of 78.74 F/g,and excellent cyclability.
2006, 35(6): 964-966.
Abstract:
The granular films of Fe-Si-O with different volume fraction x were fabricated by RF co-sputtering method. The microstructure, magnetic and transport properties, and Giant Hall Effect (GHE) were studied systematically. In room temperature and magnetic field of 1.3 Tesla, the maximum GHE value of 18.5 μΩ·cm was obtained at the volume fraction of 0.52. The origin of this giant Hall Effect is contributed to 3d local electron-electron interaction. The annealing temperature under 300℃, the saturated Hall resistivity of the Fe0.52(SiO2)0.48 granular film does no decrease much. Namely, the sample has good thermal stability, which implies that this sample may be considered as a magnetic field sensor for operating temperatures below 300℃.
The granular films of Fe-Si-O with different volume fraction x were fabricated by RF co-sputtering method. The microstructure, magnetic and transport properties, and Giant Hall Effect (GHE) were studied systematically. In room temperature and magnetic field of 1.3 Tesla, the maximum GHE value of 18.5 μΩ·cm was obtained at the volume fraction of 0.52. The origin of this giant Hall Effect is contributed to 3d local electron-electron interaction. The annealing temperature under 300℃, the saturated Hall resistivity of the Fe0.52(SiO2)0.48 granular film does no decrease much. Namely, the sample has good thermal stability, which implies that this sample may be considered as a magnetic field sensor for operating temperatures below 300℃.
2006, 35(6): 967-969,984.
Abstract:
Based on the approximation for the charge distribution, by solving poisson equations, this paper found the distributions of electric field and electrostatic potential. Then the shift of threshold voltages due to polysilicon quantization with different polysilicon doping concentrations is calculated. The calculated results are compared with the numerical simulation results.
Based on the approximation for the charge distribution, by solving poisson equations, this paper found the distributions of electric field and electrostatic potential. Then the shift of threshold voltages due to polysilicon quantization with different polysilicon doping concentrations is calculated. The calculated results are compared with the numerical simulation results.
2006, 35(6): 970-972,976.
Abstract:
Digital filtering method for frequency domain is employed to process conventional and modified off-axis reference beam computer generated holograms, then the spatial spectra of zero order image and one twin image can be eliminated, and single clear virtual image or real image can be reconstructed numerically. In this paper, fast Fourier transform algorithm is used to calculate the Fresnel diffraction integration, and the total digitization of design, fabrication, frequency filtering, and reconstruction procedures are achieved successfully. The numeric simulation by computer shows that this method has some advantages such as high signal-to-noise ratio, convenient operation procedures, fast computing speed, and high flexibility.
Digital filtering method for frequency domain is employed to process conventional and modified off-axis reference beam computer generated holograms, then the spatial spectra of zero order image and one twin image can be eliminated, and single clear virtual image or real image can be reconstructed numerically. In this paper, fast Fourier transform algorithm is used to calculate the Fresnel diffraction integration, and the total digitization of design, fabrication, frequency filtering, and reconstruction procedures are achieved successfully. The numeric simulation by computer shows that this method has some advantages such as high signal-to-noise ratio, convenient operation procedures, fast computing speed, and high flexibility.
2006, 35(6): 973-976.
Abstract:
In this paper, an improved meshing approach is proposed to improve the precision of boundary elements of the complicated domains. According to the approach, a complicated domain is meshed by the free-meshing strategy firstly, and the information of elements and nodes is generated automatically. Based on the elements and nodes information, the control points can be determined, which are used to represent the edge of boundary element by Non-Uniform Rational B-Spline (NURBS) curves. The element edges represented by NURBS can be more closed to the actual boundary by adjusting the power factors appropriately. Then, the shape functions of the improved boundary elements are deduced. Finally, an example validates the improvement is effective, and demonstrates the effect of power factors on NURBS curves.
In this paper, an improved meshing approach is proposed to improve the precision of boundary elements of the complicated domains. According to the approach, a complicated domain is meshed by the free-meshing strategy firstly, and the information of elements and nodes is generated automatically. Based on the elements and nodes information, the control points can be determined, which are used to represent the edge of boundary element by Non-Uniform Rational B-Spline (NURBS) curves. The element edges represented by NURBS can be more closed to the actual boundary by adjusting the power factors appropriately. Then, the shape functions of the improved boundary elements are deduced. Finally, an example validates the improvement is effective, and demonstrates the effect of power factors on NURBS curves.
2006, 35(6): 977-980.
Abstract:
Applying the Lie symmetry method and constructing invariants, a 1+1 dimensional nonlinear wave equation is reduced to ordinary differential equation, and its new exact solutions can be expressed by elliptic functions, trigonometric functions and so on.
Applying the Lie symmetry method and constructing invariants, a 1+1 dimensional nonlinear wave equation is reduced to ordinary differential equation, and its new exact solutions can be expressed by elliptic functions, trigonometric functions and so on.
2006, 35(6): 981-984.
Abstract:
By using theory of distance geometry and analytic method, the problem on relations about the volumes of some simplices is studied, and some new inequalities for the volumes of simplices are established. As the special case, an inequality for the volume of the pedal simplex of a simplex and other inequalities for simplices are gotten.
By using theory of distance geometry and analytic method, the problem on relations about the volumes of some simplices is studied, and some new inequalities for the volumes of simplices are established. As the special case, an inequality for the volume of the pedal simplex of a simplex and other inequalities for simplices are gotten.
2006, 35(6): 985-988.
Abstract:
This paper establishes integrative weighting model based on the analysis of agility index of dynamic alliance. This model integrates the analytic Hierarchy Process method, entropy method and mean-variance method and proposes a subjective and objective weighting method, which not only can reflect the purpose of decision-makers but also avoid the objectiveness of evaluation result. Thus this model eliminates the disadvantages of objective weighting and subjective weighting methods. The proposed method can be applied to the determination of agility index weight.
This paper establishes integrative weighting model based on the analysis of agility index of dynamic alliance. This model integrates the analytic Hierarchy Process method, entropy method and mean-variance method and proposes a subjective and objective weighting method, which not only can reflect the purpose of decision-makers but also avoid the objectiveness of evaluation result. Thus this model eliminates the disadvantages of objective weighting and subjective weighting methods. The proposed method can be applied to the determination of agility index weight.
2006, 35(6): 989-992.
Abstract:
Accounting for reliability analysis of computer systems with hardware and software, a dynamic and static Fault Tree model is presented to analyze reliability of systems. Analyzing reliability and components' importance of a sample of computer systems, this paper is focused on software reliability increment as the most crucial component for increasing system reliability effectively, and thus the importance of software reliability analysis and design is illustrated to increase the global reliability of systems distinctly.
Accounting for reliability analysis of computer systems with hardware and software, a dynamic and static Fault Tree model is presented to analyze reliability of systems. Analyzing reliability and components' importance of a sample of computer systems, this paper is focused on software reliability increment as the most crucial component for increasing system reliability effectively, and thus the importance of software reliability analysis and design is illustrated to increase the global reliability of systems distinctly.
