ISSN 
2013 Vol. 42, No. 2
2013, 42(2): 162-170.
doi: 10.3969/j.issn.1001-0548.2013.02.001
Abstract:
As system on chip (SoC) design complexity explodes, the gap between chip design and verification has been widened. How to improve verification productivity represents a great challenge to the IC industry. Recent efforts in addressing this challenge are reviewed and then a new verification paradigm, verification-while-designing, is proposed. This methodology combines hierarchical design and recursive verification, aiming at releasing the verification challenge. The fundamental points enabling the methodology are also outlined.
As system on chip (SoC) design complexity explodes, the gap between chip design and verification has been widened. How to improve verification productivity represents a great challenge to the IC industry. Recent efforts in addressing this challenge are reviewed and then a new verification paradigm, verification-while-designing, is proposed. This methodology combines hierarchical design and recursive verification, aiming at releasing the verification challenge. The fundamental points enabling the methodology are also outlined.
Substrate Integrated Waveguide (SIW) Techniques: The State-of-the-Art Developments and Future Trends
2013, 42(2): 171-192.
doi: 10.3969/j.issn.1001-0548.2013.02.002
Abstract:
The state-of-the-art developments of substrate integrated waveguide (SIW) techniques is overviewed. Various SIW-based passive and active components reported so far have demonstrated that they can be effectively integrated in the form of low-cost system-on-substrate (SoS), which provides complete packaged system solutions. Different innovative SIW beam-forming techniques are discussed. Future developments are forecasted, which suggest the expansion of substrate integrated circuits (SICs) into 3-D geometry and mixed integrations of dissimilar waveguides within the same substrate building blocks. Other SIW-related trends are also described, including non-linear and active waveguide developments as well as CMOS-based waveguide synthesis for millimeter-wave and THz applications.
The state-of-the-art developments of substrate integrated waveguide (SIW) techniques is overviewed. Various SIW-based passive and active components reported so far have demonstrated that they can be effectively integrated in the form of low-cost system-on-substrate (SoS), which provides complete packaged system solutions. Different innovative SIW beam-forming techniques are discussed. Future developments are forecasted, which suggest the expansion of substrate integrated circuits (SICs) into 3-D geometry and mixed integrations of dissimilar waveguides within the same substrate building blocks. Other SIW-related trends are also described, including non-linear and active waveguide developments as well as CMOS-based waveguide synthesis for millimeter-wave and THz applications.
2013, 42(2): 193-199.
doi: 10.3969/j.issn.1001-0548.2013.02.003
Abstract:
Network-on-chip (NoC) is a new interconnection structure which connects multiprocessors by network-based infrastructure. The data switching strategy between multiprocessors has great influence on the quality of service (QoS) of data transmission. A new switching structure which combines the dynamic virtual channels (VC) allocation and the dual-subnets infrastructure is proposed. The dynamic VC allocation is applied in order to increase the success-connection probability; while the dual-subnets infrastructure disperses data flows into XY-subnet and YX-subnet, avoids transmission congestion, and thus reduces packet transmission delay. The simulation results show that this Dyn-Dualnet-QoS strategy can provide great QoS guarantee for various levels of packet transmissions.
Network-on-chip (NoC) is a new interconnection structure which connects multiprocessors by network-based infrastructure. The data switching strategy between multiprocessors has great influence on the quality of service (QoS) of data transmission. A new switching structure which combines the dynamic virtual channels (VC) allocation and the dual-subnets infrastructure is proposed. The dynamic VC allocation is applied in order to increase the success-connection probability; while the dual-subnets infrastructure disperses data flows into XY-subnet and YX-subnet, avoids transmission congestion, and thus reduces packet transmission delay. The simulation results show that this Dyn-Dualnet-QoS strategy can provide great QoS guarantee for various levels of packet transmissions.
2013, 42(2): 200-204.
doi: 10.3969/j.issn.1001-0548.2013.02.004
Abstract:
For traditional finite-impulse-response (FIR) filter, designers usually default to that the coefficient should be adjacent. In this paper, we propose a new model of the FIR filter based on the L0-norm, which improves the performance of FIR filter by increasing few delays and keeps the linear phase at the same time. Genetic algorithm is proposed to solve the proposed non-convex optimization model. An approximate solution is derived based on the result of genetic algorithm to reduce the computational burden. Computer simulation results demonstrate its lower approximation error compared with traditional FIR filters with the same filter order.
For traditional finite-impulse-response (FIR) filter, designers usually default to that the coefficient should be adjacent. In this paper, we propose a new model of the FIR filter based on the L0-norm, which improves the performance of FIR filter by increasing few delays and keeps the linear phase at the same time. Genetic algorithm is proposed to solve the proposed non-convex optimization model. An approximate solution is derived based on the result of genetic algorithm to reduce the computational burden. Computer simulation results demonstrate its lower approximation error compared with traditional FIR filters with the same filter order.
2013, 42(2): 205-208.
doi: 10.3969/j.issn.1001-0548.2013.02.005
Abstract:
Compared with Turbo codes, nonbinary low-density parity-check (LDPC) codes have the better waterfall and error floor performance. The nonbinary LDPC codes are applied to decode-and-forward (DF) cooperative communications in this paper, and a multiuser cooperative scheme based on outage probability is proposed. Each user decides its relay by judging whether its channel to the source node is in outage or not. In case the channel is not in outage, the user decodes the received signal from the source node, and encodes it using nonbinary LDPC codes before forwarding to the destination. The parity-check matrix of nonbinary LDPC codes consists of information part and parity-check part. The information part is quasi-cyclic, and the parity-check part is the dual-diagonal structure. Simulation results show that, compared with the random cooperative scheme, the proposed scheme can achieve about 0.3 dB and 0.4 dB performance gains at the bit error rate (BER) of 10-4 on Gaussian channel and Rayleigh fading channel, respectively.
Compared with Turbo codes, nonbinary low-density parity-check (LDPC) codes have the better waterfall and error floor performance. The nonbinary LDPC codes are applied to decode-and-forward (DF) cooperative communications in this paper, and a multiuser cooperative scheme based on outage probability is proposed. Each user decides its relay by judging whether its channel to the source node is in outage or not. In case the channel is not in outage, the user decodes the received signal from the source node, and encodes it using nonbinary LDPC codes before forwarding to the destination. The parity-check matrix of nonbinary LDPC codes consists of information part and parity-check part. The information part is quasi-cyclic, and the parity-check part is the dual-diagonal structure. Simulation results show that, compared with the random cooperative scheme, the proposed scheme can achieve about 0.3 dB and 0.4 dB performance gains at the bit error rate (BER) of 10-4 on Gaussian channel and Rayleigh fading channel, respectively.
2013, 42(2): 209-213.
doi: 10.3969/j.issn.1001-0548.2013.02.006
Abstract:
A detection algorithm based on dual-sliding-window is proposed for the detection of channel impulse response (CIR). In OFDM systems with coherent demodulation, the precision of channel estimation has a significant impact on the performance of receivers. However, traditional threshold detection algorithms adopted by time domain channel estimation of OFDM systems is sensitive to noise. In the presence of low-level CIR components, false detection and miss detection occur frequently if the traditional method is adopted, resulting in an inevitable precision loss. According to the cause and the characteristic of low-level CIR, an improved robust CIR detection algorithm is derived in this paper. The detection performance is investigated and simulated. Experimental results verified the theoretical analysis and the validity of the proposed scheme.
A detection algorithm based on dual-sliding-window is proposed for the detection of channel impulse response (CIR). In OFDM systems with coherent demodulation, the precision of channel estimation has a significant impact on the performance of receivers. However, traditional threshold detection algorithms adopted by time domain channel estimation of OFDM systems is sensitive to noise. In the presence of low-level CIR components, false detection and miss detection occur frequently if the traditional method is adopted, resulting in an inevitable precision loss. According to the cause and the characteristic of low-level CIR, an improved robust CIR detection algorithm is derived in this paper. The detection performance is investigated and simulated. Experimental results verified the theoretical analysis and the validity of the proposed scheme.
2013, 42(2): 214-218,224.
doi: 10.3969/j.issn.1001-0548.2013.02.007
Abstract:
A blind source separation algorithm based on correntropy is presented. Unlike the traditional independent component analysis (ICA) method which utilizes the forth-order statistics or temporal structure to achieve the blind source separation. This algorithm is motivated from the notion of correntropy in the information theoretic learning, utilizing the even statistics implied in correntropy. The cost function is established according to the relationship between the parametric centered correntropy and the independence measure, and then minimized by using the optimization algorithm to acquire the demixing matrix and separate the signal. Simulations show that the performance is better than the traditional ICA method when separating the mixture of the super-Gaussian source and sub-Gaussian source.
A blind source separation algorithm based on correntropy is presented. Unlike the traditional independent component analysis (ICA) method which utilizes the forth-order statistics or temporal structure to achieve the blind source separation. This algorithm is motivated from the notion of correntropy in the information theoretic learning, utilizing the even statistics implied in correntropy. The cost function is established according to the relationship between the parametric centered correntropy and the independence measure, and then minimized by using the optimization algorithm to acquire the demixing matrix and separate the signal. Simulations show that the performance is better than the traditional ICA method when separating the mixture of the super-Gaussian source and sub-Gaussian source.
2013, 42(2): 225-228.
doi: 10.3969/j.issn.1001-0548.2013.02.009
Abstract:
Based on Pei sampling-type DFRFT algorithm, a novel method of linear frequency-modulated pulse compression is proposed. Through zero padding and prolongation, the time delay estimation of linear frequency-modulated (LFM) pulse is transformed into the center frequency estimation. In this way, the result approximate to the conventional LFM pulse compression can be obtained by utilizing the LFM pulse energy concentration of fractional Fourier transform. The analytic expression of discrete range-finding estimator is derived and the corresponding dispersion accuracy and the influence of Doppler shift are analyzed. It is found that the proposed method has strong robustness on Doppler shift, and reduces the computation complexity by half without the decline of range-finding accuracy. The simulations prove the above-mentioned theories.
Based on Pei sampling-type DFRFT algorithm, a novel method of linear frequency-modulated pulse compression is proposed. Through zero padding and prolongation, the time delay estimation of linear frequency-modulated (LFM) pulse is transformed into the center frequency estimation. In this way, the result approximate to the conventional LFM pulse compression can be obtained by utilizing the LFM pulse energy concentration of fractional Fourier transform. The analytic expression of discrete range-finding estimator is derived and the corresponding dispersion accuracy and the influence of Doppler shift are analyzed. It is found that the proposed method has strong robustness on Doppler shift, and reduces the computation complexity by half without the decline of range-finding accuracy. The simulations prove the above-mentioned theories.
2013, 42(2): 229-233.
doi: 10.3969/j.issn.1001-0548.2013.02.010
Abstract:
The transmission and suppression of the simultaneous switching noise (SSN) are investigated based on microwave network principle. A new method for the suppression of the noise transmission with multi-stage capacitors is presented in this paper. The design rules of the method with multi-stage capacitors are derived. The simulation results show that using the multi-row distributed capacitors and increasing transmission loss of noise path could improve the ability to suppress the noise transmission and increase the efficiency of the noise suppression with capacitors. Finally, the performance of the method is verified with finite difference time domain(FDTD) simulations and measured results.
The transmission and suppression of the simultaneous switching noise (SSN) are investigated based on microwave network principle. A new method for the suppression of the noise transmission with multi-stage capacitors is presented in this paper. The design rules of the method with multi-stage capacitors are derived. The simulation results show that using the multi-row distributed capacitors and increasing transmission loss of noise path could improve the ability to suppress the noise transmission and increase the efficiency of the noise suppression with capacitors. Finally, the performance of the method is verified with finite difference time domain(FDTD) simulations and measured results.
2013, 42(2): 234-238.
doi: 10.3969/j.issn.1001-0548.2013.02.011
Abstract:
Based on the Maxwell equations and boundary conditions, the dispersion relation of the surface plasmon, which is excited by electrons moving above the metal surface, was theoretically analyzed. And the two cases: the electrons moving above the bulk metal and above the metal film, were studied respectively. Also, the particle-in-cell code was carried out to simulate above these two cases, and the results agreed well with the theoretical analysis.
Based on the Maxwell equations and boundary conditions, the dispersion relation of the surface plasmon, which is excited by electrons moving above the metal surface, was theoretically analyzed. And the two cases: the electrons moving above the bulk metal and above the metal film, were studied respectively. Also, the particle-in-cell code was carried out to simulate above these two cases, and the results agreed well with the theoretical analysis.
2013, 42(2): 239-243.
doi: 10.3969/j.issn.1001-0548.2013.02.012
Abstract:
The periodic model is generally used for analyzing the far field of reflectarrays. However, such model differs from the realistic array configuration that the reflectarray is composed of different size elements. Considering the faults of conventional method, this paper brings forward a new far field pattern analysis approach by the name of ‘element-in-array model’. Based on the superposition principle and the equivalence principle, element-in-array pattern can be calculated from the equivalent surface electric/magnetic currents by electric field integral equation. Numerical results validate its accuracy and effectiveness. The new approach provides a feasible solution for analyzing large-scale planar/conformal array antennas.
The periodic model is generally used for analyzing the far field of reflectarrays. However, such model differs from the realistic array configuration that the reflectarray is composed of different size elements. Considering the faults of conventional method, this paper brings forward a new far field pattern analysis approach by the name of ‘element-in-array model’. Based on the superposition principle and the equivalence principle, element-in-array pattern can be calculated from the equivalent surface electric/magnetic currents by electric field integral equation. Numerical results validate its accuracy and effectiveness. The new approach provides a feasible solution for analyzing large-scale planar/conformal array antennas.
2013, 42(2): 244-248.
doi: 10.3969/j.issn.1001-0548.2013.02.013
Abstract:
In view of the limitation on the performance of the Boost converter when the general controller is used, such as low-bandwidth and sluggish dynamic response. This paper proposes a novel nonlinear control scheme which is based on the capacitor charge balance control (CBC). Combined with the linear/nonlinear control method, the traditional voltage mode control is taken during the steady-state of the Boost converter, the scheme switches to the nonlinear control method while the load current has a step change. Using the CBC algorithm during the calculation of the switching time, the optimal dynamic performance of the Boost converter is achieved. Finally, the simulation results and the experimental results of the prototype show that the proposed algorithm, compared with the traditional voltage mode control, can significantly improve the dynamic performance of the Boost converter, such as the overshoot, dynamic setting time.
In view of the limitation on the performance of the Boost converter when the general controller is used, such as low-bandwidth and sluggish dynamic response. This paper proposes a novel nonlinear control scheme which is based on the capacitor charge balance control (CBC). Combined with the linear/nonlinear control method, the traditional voltage mode control is taken during the steady-state of the Boost converter, the scheme switches to the nonlinear control method while the load current has a step change. Using the CBC algorithm during the calculation of the switching time, the optimal dynamic performance of the Boost converter is achieved. Finally, the simulation results and the experimental results of the prototype show that the proposed algorithm, compared with the traditional voltage mode control, can significantly improve the dynamic performance of the Boost converter, such as the overshoot, dynamic setting time.
2013, 42(2): 249-253.
doi: 10.3969/j.issn.1001-0548.2013.02.014
Abstract:
This paper evaluates moderate-resolution imaging spectroradiometer (MODIS) shortwave land surface albedo products over multiple land cover types, especially the impact of snow on these data. We choose 19 sites from AmeriFLUX to validate MODIS shortwave albedo products in the year of 2005. These sites are covered by evergreen needleleaf forest, deciduous broadleaf forest, grassland, wetland, shrubland and cropland. For every vegetation type, the albedo inversion quality is worse with snow cover than snow free. Snow has the most impact on evergreen needleleaf forests than others. For this land cover type, the bias, root-mean-square error (RMSE) and standard deviation (STD) performances of albedo inversion increase from -0.002 3, 0.023 0, and 0.011 4 to 0.082 5, 0.108 5 and 0.086 6, respectively. For all data, the total bias, RMSE and STD increase from 0.020 6, 0.057 2 and 0.0539 to 0.035 5, 0.121 7 and 0.187 with effect of snow.
This paper evaluates moderate-resolution imaging spectroradiometer (MODIS) shortwave land surface albedo products over multiple land cover types, especially the impact of snow on these data. We choose 19 sites from AmeriFLUX to validate MODIS shortwave albedo products in the year of 2005. These sites are covered by evergreen needleleaf forest, deciduous broadleaf forest, grassland, wetland, shrubland and cropland. For every vegetation type, the albedo inversion quality is worse with snow cover than snow free. Snow has the most impact on evergreen needleleaf forests than others. For this land cover type, the bias, root-mean-square error (RMSE) and standard deviation (STD) performances of albedo inversion increase from -0.002 3, 0.023 0, and 0.011 4 to 0.082 5, 0.108 5 and 0.086 6, respectively. For all data, the total bias, RMSE and STD increase from 0.020 6, 0.057 2 and 0.0539 to 0.035 5, 0.121 7 and 0.187 with effect of snow.
2013, 42(2): 254-259.
doi: 10.3969/j.issn.1001-0548.2013.02.015
Abstract:
The airport noise isoline map plays an important role in airport noise control and airport planning. After studying airport noise characteristics and distribution, an airport noise isoline tracking algorithm based on route grid is proposed. By constructing an effective grid and creating route grid with the point code sum, the next equivalent point can be determined definitely in isoline tacking. The proposed algorithm can generate the isoline map rapidly by avoiding open isoline tracking first and then closed one Experimental results show that the proposed algorithm has more efficient performance, and generates the better airport noise isoline map, especially with no cross between isolines.
The airport noise isoline map plays an important role in airport noise control and airport planning. After studying airport noise characteristics and distribution, an airport noise isoline tracking algorithm based on route grid is proposed. By constructing an effective grid and creating route grid with the point code sum, the next equivalent point can be determined definitely in isoline tacking. The proposed algorithm can generate the isoline map rapidly by avoiding open isoline tracking first and then closed one Experimental results show that the proposed algorithm has more efficient performance, and generates the better airport noise isoline map, especially with no cross between isolines.
2013, 42(2): 260-265.
doi: 10.3969/j.issn.1001-0548.2013.02.016
Abstract:
The researches on digital watermarking algorithm based on semantics are hot issues in the field of audio content management. The indexing method of semantic management for audio watermarking based on uniform content locator (UCL) is introduced, and a dual watermarking algorithm based on radical basis function neural network (RBFNN) is proposed. In semantic watermarking model, RBFNN is used to adaptively select the best embedding place of watermarking in the audio data segment, and the wavelet transform is also adopted to extract the approximate weight and the detail component of the selected audio segment. The different audio indexing information as dual semantic watermarking are embedded into the corresponding audio signal, and the constructed dual semantic watermarking model can realize the integration transmission target with semantic information and original audio signal. Furthermore, synchronous code technology is utilized to solve the problem of effective watermarking detection and monitoring. The results show that the proposed strategy can bring excellent robustness and non-auditory while the embedded watermarking is semantic information with large amount of information.
The researches on digital watermarking algorithm based on semantics are hot issues in the field of audio content management. The indexing method of semantic management for audio watermarking based on uniform content locator (UCL) is introduced, and a dual watermarking algorithm based on radical basis function neural network (RBFNN) is proposed. In semantic watermarking model, RBFNN is used to adaptively select the best embedding place of watermarking in the audio data segment, and the wavelet transform is also adopted to extract the approximate weight and the detail component of the selected audio segment. The different audio indexing information as dual semantic watermarking are embedded into the corresponding audio signal, and the constructed dual semantic watermarking model can realize the integration transmission target with semantic information and original audio signal. Furthermore, synchronous code technology is utilized to solve the problem of effective watermarking detection and monitoring. The results show that the proposed strategy can bring excellent robustness and non-auditory while the embedded watermarking is semantic information with large amount of information.
2013, 42(2): 266-271.
doi: 10.3969/j.issn.1001-0548.2013.02.017
Abstract:
A correction method for feature points mismatching is proposed based on improved shape context, aiming at the mismatching problem of corresponding points needed for the depth estimation for the bifocal image. First, the SSURF feature descriptor is presented, as it has good invariability to changes such as scaling, view angles and illumination. By the use of SSURF feature vector matching, object images which had been obtained based on a monocular stereo vision system are processed in two different focal length images, so corresponding SSURF feature points are obtained. Then, an improved shape context descriptor is proposed to correct the error matching of local feature points. The distance between dimensional target points as well as image points and the center of the image, and the geometric relationship between the camera focal lengths are used to complete the related computation and therefore to obtain the depth information of object by using the corrected feature points. The experimental results show that the correction method introduced has small errors for depth estimation and good effect for estimation.
A correction method for feature points mismatching is proposed based on improved shape context, aiming at the mismatching problem of corresponding points needed for the depth estimation for the bifocal image. First, the SSURF feature descriptor is presented, as it has good invariability to changes such as scaling, view angles and illumination. By the use of SSURF feature vector matching, object images which had been obtained based on a monocular stereo vision system are processed in two different focal length images, so corresponding SSURF feature points are obtained. Then, an improved shape context descriptor is proposed to correct the error matching of local feature points. The distance between dimensional target points as well as image points and the center of the image, and the geometric relationship between the camera focal lengths are used to complete the related computation and therefore to obtain the depth information of object by using the corrected feature points. The experimental results show that the correction method introduced has small errors for depth estimation and good effect for estimation.
2013, 42(2): 272-276.
doi: 10.3969/j.issn.1001-0548.2013.02.018
Abstract:
Support vector machine (SVM) is widely used in pattern classification. In order to solve the privacy preserving problem in SVM, a privacy preserving learning machine for large scale datasets (PPLM) is proposed in this paper. First, core vector machine (CVM) is introduced for sampling the large scale datasets; then two points from different classes are chosen in the core set and the hyperplane orthogonal to the line connecting these two points is treated as the optimal separating hyperplane. Experimental results obtained from synthetic and standard datasets verify that the PPLM is effective and competitive.
Support vector machine (SVM) is widely used in pattern classification. In order to solve the privacy preserving problem in SVM, a privacy preserving learning machine for large scale datasets (PPLM) is proposed in this paper. First, core vector machine (CVM) is introduced for sampling the large scale datasets; then two points from different classes are chosen in the core set and the hyperplane orthogonal to the line connecting these two points is treated as the optimal separating hyperplane. Experimental results obtained from synthetic and standard datasets verify that the PPLM is effective and competitive.
2013, 42(2): 277-282.
doi: 10.3969/j.issn.1001-0548.2013.02.019
Abstract:
The theoretic spreading results under an urban scenario with equilibrium traffic are analyzed through modeling mobility pattern, communication channel, medium access control, worm propagation, and others. The extensive Monte Carlo simulations uncover the effects of the transmission range (from a typical minimum to a maximum), the minimum velocity and the maximum velocity (from the free flow to the congested traffic), and the vehicle density (from a sparse topology to a dense spatial relation) on epidemic spreading of such worms in vehicular ad hoc networks. Further, the wireless worm propagation in the same scenario with dynamic traffic is simulated by using network simulation software, the correlation between theoretic results and practical outcome is discussed, and the reasons resulting in the local differences are also analyzed.
The theoretic spreading results under an urban scenario with equilibrium traffic are analyzed through modeling mobility pattern, communication channel, medium access control, worm propagation, and others. The extensive Monte Carlo simulations uncover the effects of the transmission range (from a typical minimum to a maximum), the minimum velocity and the maximum velocity (from the free flow to the congested traffic), and the vehicle density (from a sparse topology to a dense spatial relation) on epidemic spreading of such worms in vehicular ad hoc networks. Further, the wireless worm propagation in the same scenario with dynamic traffic is simulated by using network simulation software, the correlation between theoretic results and practical outcome is discussed, and the reasons resulting in the local differences are also analyzed.
2013, 42(2): 283-288,299.
doi: 10.3969/j.issn.1001-0548.2013.02.020
Abstract:
This paper proposes a network code construction method which has low decoding delay. The key idea of this method is that, among all the disjoint paths from the source to a destination, one path is selected as “convenient path”, on which packets are delivered directly without coding. Allocating maximum number of convenient paths for all the destinations in a multicast network can be modeled as the problem of maximal complete sub-graph. Both theoretical analysis and numerical results from example networks show that the proposed network code construction method can reduce the decoding delay effectively without any reduction in throughput benefit of network coding. The method introduced by this paper can serve as an efficient way for transmitting data of delay sensitive applications such as media streaming.
This paper proposes a network code construction method which has low decoding delay. The key idea of this method is that, among all the disjoint paths from the source to a destination, one path is selected as “convenient path”, on which packets are delivered directly without coding. Allocating maximum number of convenient paths for all the destinations in a multicast network can be modeled as the problem of maximal complete sub-graph. Both theoretical analysis and numerical results from example networks show that the proposed network code construction method can reduce the decoding delay effectively without any reduction in throughput benefit of network coding. The method introduced by this paper can serve as an efficient way for transmitting data of delay sensitive applications such as media streaming.
2013, 42(2): 289-294.
doi: 10.3969/j.issn.1001-0548.2013.02.021
Abstract:
By analyzing the security issues and security demand of mobile internet capability open platform, this paper introduces an architecture of mobile internet capability open platform and proposes a hierarchical security service model and the key technology in detail. The hierarchy security service model has been applied in a related project, the application shows that the security model can provide with perfect safety protection and flexible security services etc.
By analyzing the security issues and security demand of mobile internet capability open platform, this paper introduces an architecture of mobile internet capability open platform and proposes a hierarchical security service model and the key technology in detail. The hierarchy security service model has been applied in a related project, the application shows that the security model can provide with perfect safety protection and flexible security services etc.
2013, 42(2): 295-299.
doi: 10.3969/j.issn.1001-0548.2013.02.022
Abstract:
Wireless positioning technologies and location-based services have gained much attention and development over the past several years. As a compensate to global positioning system (GPS), Wi-Fi positioning, Wi-Fi fingerprinting in particular, which makes use of widely-deployed wireless LANs, has been accepted as a common solution to indoor positioning. Due to the interference of various factors during the signal transmission, positioning accuracy is often degraded and unstable. The estimation of the room and the floor that the user is in is often wrong. This paper proposes to use a history-based Wi-Fi fingerprinting algorithm in combination with the interior structure of the building for indoor positioning. Experiments show that the enhanced algorithm is able to improve the accuracy and stability of Wi-Fi fingerprinting and reduce wrong estimations of rooms and floors. Furthermore, this paper proposes a multi-floor handling algorithm which is able to reduce wrong estimations of floors.
Wireless positioning technologies and location-based services have gained much attention and development over the past several years. As a compensate to global positioning system (GPS), Wi-Fi positioning, Wi-Fi fingerprinting in particular, which makes use of widely-deployed wireless LANs, has been accepted as a common solution to indoor positioning. Due to the interference of various factors during the signal transmission, positioning accuracy is often degraded and unstable. The estimation of the room and the floor that the user is in is often wrong. This paper proposes to use a history-based Wi-Fi fingerprinting algorithm in combination with the interior structure of the building for indoor positioning. Experiments show that the enhanced algorithm is able to improve the accuracy and stability of Wi-Fi fingerprinting and reduce wrong estimations of rooms and floors. Furthermore, this paper proposes a multi-floor handling algorithm which is able to reduce wrong estimations of floors.
2013, 42(2): 300-305.
doi: 10.3969/j.issn.1001-0548.2013.02.023
Abstract:
The security attributes of certified e-mail protocol include confidentiality, non-repudiation, fairness. Aiming at to remedy the lack of confidentiality and non-repudiation of the a typical certified mail protocol, an improved certified mail protocol with transparent semi-trusted third party is proposed. To improve the protocol efficiency, a method applying Kailar logic in compositional analysis is proposed for analyzing the improved protocol. The analysis results indicate the improved protocol can meet confidentiality and non-repudiation.
The security attributes of certified e-mail protocol include confidentiality, non-repudiation, fairness. Aiming at to remedy the lack of confidentiality and non-repudiation of the a typical certified mail protocol, an improved certified mail protocol with transparent semi-trusted third party is proposed. To improve the protocol efficiency, a method applying Kailar logic in compositional analysis is proposed for analyzing the improved protocol. The analysis results indicate the improved protocol can meet confidentiality and non-repudiation.
2013, 42(2): 306-310.
doi: 10.3969/j.issn.1001-0548.2013.02.024
Abstract:
The conventional stress-strength interference (SSI) model is a basic model for reliability analysis of mechanical components. In this model, the component reliability is defined as the probability of the strength random variable larger than the stress random variable. But for a component under circular fatigue loads conditions, its reliability can not be calculated directly by using the SSI model. To evaluate the structural reliability under circular fatigue loads, an expression of residual strength under circular fatigue loads is derived firstly in the assumption that the initial strength is a random variable which follows any distribution. Then, a stress-strength interference model under circular fatigue loads is proposed by employing the universal generating function to calculate the probability characteristics of a function constituted by residual strength and fatigue loads. Finally, the fatigue experimental data of 45# steel is used to testify and analyze the proposed model. The results indicate that the proposed model can be used to evaluate the structural reliability under circular fatigue loads.
The conventional stress-strength interference (SSI) model is a basic model for reliability analysis of mechanical components. In this model, the component reliability is defined as the probability of the strength random variable larger than the stress random variable. But for a component under circular fatigue loads conditions, its reliability can not be calculated directly by using the SSI model. To evaluate the structural reliability under circular fatigue loads, an expression of residual strength under circular fatigue loads is derived firstly in the assumption that the initial strength is a random variable which follows any distribution. Then, a stress-strength interference model under circular fatigue loads is proposed by employing the universal generating function to calculate the probability characteristics of a function constituted by residual strength and fatigue loads. Finally, the fatigue experimental data of 45# steel is used to testify and analyze the proposed model. The results indicate that the proposed model can be used to evaluate the structural reliability under circular fatigue loads.
2013, 42(2): 311-315.
doi: 10.3969/j.issn.1001-0548.2013.02.025
Abstract:
The reliability of an actual load-sharing parallel system is greatly affected by total load of the system and load capacity of components. A failure rate variation model of components of unrepaired load-sharing parallel systems is established by analyzing the components' load capacity. Through Markov process, the universal reliability model of load-sharing parallel systems is established. According to the failure rate variation model and the relations between total load of system and load capacity of components, the universal reliability model is classified into ideal load capacity model, maximum load capacity model, and critical load capacity model. The reliability of these three models is derived in this paper. The models and calculation results are verified via case study the reliability analysis of parallel systems with independent components and m/n:(F) voting system.
The reliability of an actual load-sharing parallel system is greatly affected by total load of the system and load capacity of components. A failure rate variation model of components of unrepaired load-sharing parallel systems is established by analyzing the components' load capacity. Through Markov process, the universal reliability model of load-sharing parallel systems is established. According to the failure rate variation model and the relations between total load of system and load capacity of components, the universal reliability model is classified into ideal load capacity model, maximum load capacity model, and critical load capacity model. The reliability of these three models is derived in this paper. The models and calculation results are verified via case study the reliability analysis of parallel systems with independent components and m/n:(F) voting system.
2013, 42(2): 316-320.
doi: 10.3969/j.issn.1001-0548.2013.02.026
Abstract:
On the basis of the -N curved surface, the fatigue life of turbine disk is investigated in this paper by constructing Goodman and Gerber types of generalized -N curved surface equation based on stress amplitude and mean stress. An example of an aircraft engine turbine disk is presented to validate the proposed method, and the results show that the prediction from Goodman equivalent life curve is much better than that of Gerber type model. In addition, there is no need to equivalently convert the cyclic stress in above method. This method can improve the accuracy of fatigue life estimation.
On the basis of the -N curved surface, the fatigue life of turbine disk is investigated in this paper by constructing Goodman and Gerber types of generalized -N curved surface equation based on stress amplitude and mean stress. An example of an aircraft engine turbine disk is presented to validate the proposed method, and the results show that the prediction from Goodman equivalent life curve is much better than that of Gerber type model. In addition, there is no need to equivalently convert the cyclic stress in above method. This method can improve the accuracy of fatigue life estimation.
