ISSN 
2015 Vol. 44, No. 1
2015, 44(1): 2-11.
doi: 10.3969/j.issn.1001-0548.2015.01.001
Abstract:
With the wide application of complex networks in many fields, how to improve the transportation efficiency has become the bottleneck of its further development in practice. This article classifies these routing ways from four aspects-reassigning the distribution of nodes' capacity and links' bandwidth, modifying network topology, designing routing strategies, and proposing queuing strategies. we also introduce some influential strategies in detail. Finally, we point out some potential directions in the future. This work is helpful for new learners and researchers to be familiar with this field and may be helpful for network designers or regulators to improve the network efficiency and avoid traffic jams.
With the wide application of complex networks in many fields, how to improve the transportation efficiency has become the bottleneck of its further development in practice. This article classifies these routing ways from four aspects-reassigning the distribution of nodes' capacity and links' bandwidth, modifying network topology, designing routing strategies, and proposing queuing strategies. we also introduce some influential strategies in detail. Finally, we point out some potential directions in the future. This work is helpful for new learners and researchers to be familiar with this field and may be helpful for network designers or regulators to improve the network efficiency and avoid traffic jams.
2015, 44(1): 12-21.
doi: 10.3969/j.issn.1001-0548.2015.01.002
Abstract:
In this paper, we review the related works in explosive percolation, and give a detailed description of typical models and the main conclusions. Moreover, we show the applications of the explosive percolation in real-world networks. Lastly, we put forward a prospection of the research on the percolation.
In this paper, we review the related works in explosive percolation, and give a detailed description of typical models and the main conclusions. Moreover, we show the applications of the explosive percolation in real-world networks. Lastly, we put forward a prospection of the research on the percolation.
2015, 44(1): 22-27.
doi: 10.3969/j.issn.1001-0548.2015.01.003
Abstract:
Recently, the super-resolution methods based on sparse representation has became a research hotpot in signal processing. How to calculate the sparse coefficients fast and accurately is the key of sparse representation algorithm. In this paper, we propose a feature sign method to compute the sparse coefficients in the search step. Inspired by the compressed sensing theory, two dictionaries are jointly learnt to conduct super-resolution in this method. The feature sign algorithm changes the non-convex problem to a convex one by guessing the sign of the sparse coefficient at each iteration. It improves the accuracy of the obtained sparse coefficients and speeds the algorithm. Simulation results show that the proposed scheme outperforms the interpolation methods and classic sparse representation algorithms in both subjective inspects and quantitative evaluations.
Recently, the super-resolution methods based on sparse representation has became a research hotpot in signal processing. How to calculate the sparse coefficients fast and accurately is the key of sparse representation algorithm. In this paper, we propose a feature sign method to compute the sparse coefficients in the search step. Inspired by the compressed sensing theory, two dictionaries are jointly learnt to conduct super-resolution in this method. The feature sign algorithm changes the non-convex problem to a convex one by guessing the sign of the sparse coefficient at each iteration. It improves the accuracy of the obtained sparse coefficients and speeds the algorithm. Simulation results show that the proposed scheme outperforms the interpolation methods and classic sparse representation algorithms in both subjective inspects and quantitative evaluations.
2015, 44(1): 28-32.
doi: 10.3969/j.issn.1001-0548.2015.01.004
Abstract:
New-style high resolution WorldView-2 satellite images pose challenges to the image fusion techniques. A new pansharpening method is proposed in this paper. First, 8-band multispectral imagery is resampled by nearest neighbor interpolation. According to the relative spectral responses between the multispectral band and the panchromatic band, a low spatial resolution panchromatic image is evaluated through multivariate linear regression. The spatial details are extracted from the original panchromatic image, and then injected into the component space of multispectral imagery. Finally, the pansharpened results are produced by employing inverse correspondence analysis transform. The experimental results show that the proposed method can obtain a better trade-off between the spatial resolution enhancement and the spectral information preservation compared to some existing methods.
New-style high resolution WorldView-2 satellite images pose challenges to the image fusion techniques. A new pansharpening method is proposed in this paper. First, 8-band multispectral imagery is resampled by nearest neighbor interpolation. According to the relative spectral responses between the multispectral band and the panchromatic band, a low spatial resolution panchromatic image is evaluated through multivariate linear regression. The spatial details are extracted from the original panchromatic image, and then injected into the component space of multispectral imagery. Finally, the pansharpened results are produced by employing inverse correspondence analysis transform. The experimental results show that the proposed method can obtain a better trade-off between the spatial resolution enhancement and the spectral information preservation compared to some existing methods.
2015, 44(1): 33-38.
doi: 10.3969/j.issn.1001-0548.2015.01.005
Abstract:
To further improve information transmission rate of wireless relay networks, an efficient downlink transmission scheme based on complex field network coding is proposed in this paper. Specifically, different from traditional information transmission scheme, the proposed downlink transmission scheme employs complex field network coding of time dimension, and each relay encodes the source symbols of multiple time slots received by complex field network coding, and transmits the encoded symbols to destinations simultaneously. Based on the data received from multiple relays, joint maximum likelihood multiuser detection is adopted at destinations to achieve the source symbols. Performance analysis and simulation results show that the symbol error probability (SEP) of the downlink transmission scheme is much less than the conventional relay transmission scheme. Moreover, the scheme can obtain higher information transmission rate and network throughput.
To further improve information transmission rate of wireless relay networks, an efficient downlink transmission scheme based on complex field network coding is proposed in this paper. Specifically, different from traditional information transmission scheme, the proposed downlink transmission scheme employs complex field network coding of time dimension, and each relay encodes the source symbols of multiple time slots received by complex field network coding, and transmits the encoded symbols to destinations simultaneously. Based on the data received from multiple relays, joint maximum likelihood multiuser detection is adopted at destinations to achieve the source symbols. Performance analysis and simulation results show that the symbol error probability (SEP) of the downlink transmission scheme is much less than the conventional relay transmission scheme. Moreover, the scheme can obtain higher information transmission rate and network throughput.
2015, 44(1): 39-42.
doi: 10.3969/j.issn.1001-0548.2015.01.006
Abstract:
Three-particle W state decoy is introduced in controlled quantum secure direct communication to improve the eavesdropping detection probability and prevent the double-CNOT attack. Each particle of three-particle W state decoy is inserted into sending particles to detect eavesdroppers. The decoy particles inserted randomly can prevent the receiver from obtaining the correct correlation between particle 1 and particle 2 before sender coding on them, so that he can not get any secret information without controller's permission. In the security analysis, the maximum amount of information in a qubit is obtained by introducing the entropy theory method, and two decoy strategies are compared quantitatively. If eavesdroppers intend to eavesdrop on secret information, the per qubit detection rate can reach 64% by using three-particle W state as decoy, but 58% by using extended three-particle GHZ state as decoy.
Three-particle W state decoy is introduced in controlled quantum secure direct communication to improve the eavesdropping detection probability and prevent the double-CNOT attack. Each particle of three-particle W state decoy is inserted into sending particles to detect eavesdroppers. The decoy particles inserted randomly can prevent the receiver from obtaining the correct correlation between particle 1 and particle 2 before sender coding on them, so that he can not get any secret information without controller's permission. In the security analysis, the maximum amount of information in a qubit is obtained by introducing the entropy theory method, and two decoy strategies are compared quantitatively. If eavesdroppers intend to eavesdrop on secret information, the per qubit detection rate can reach 64% by using three-particle W state as decoy, but 58% by using extended three-particle GHZ state as decoy.
2015, 44(1): 43-49.
Abstract:
In this paper, a remote image fusion method based on dual tree compactly supported shearlet transform (DT CSST) is proposed. In the method, the shift variant property is compensated by the dual tree structure, DT CSST combining with the PCA or IHS transform is applied in the remote image fusion. Through the QuickBird and IKONOS data, the experiments suggest that the proposed method is superior to other methods based on other multi-scale transforms, such as DWT, dual tree complex wavelet transform (DT CWT), à trous wavelet, curvelet and à trous shearlet transform.
In this paper, a remote image fusion method based on dual tree compactly supported shearlet transform (DT CSST) is proposed. In the method, the shift variant property is compensated by the dual tree structure, DT CSST combining with the PCA or IHS transform is applied in the remote image fusion. Through the QuickBird and IKONOS data, the experiments suggest that the proposed method is superior to other methods based on other multi-scale transforms, such as DWT, dual tree complex wavelet transform (DT CWT), à trous wavelet, curvelet and à trous shearlet transform.
2015, 44(1): 50-54.
doi: 10.3969/j.issn.1001-0548.2015.01.008
Abstract:
Since the features of jammer are similar to that of target echoes, the deception jamming poses a most serious threat to military radar. Therefore, there is an urgent need for new radar anti deception jamming methods. In order to accomplish radar anti deception jamming, it is necessary to analyze and extract the different features of the deception jamming and target echo. The mathematical models of deception jamming and target echo are given and studied firstly, then the differences in the amplitude undulation features, high order cumulant features and bispectrum features between the deception jamming and target echo are compared. Based on the results of feature analysis, the feature extraction methods applied in radar anti deception jamming are proposed and three feature factors are defined, then the feature parameters aggregate is built. Finally, the feature extraction methods are verified with simulation and real data in an actual deception jamming experiment.
Since the features of jammer are similar to that of target echoes, the deception jamming poses a most serious threat to military radar. Therefore, there is an urgent need for new radar anti deception jamming methods. In order to accomplish radar anti deception jamming, it is necessary to analyze and extract the different features of the deception jamming and target echo. The mathematical models of deception jamming and target echo are given and studied firstly, then the differences in the amplitude undulation features, high order cumulant features and bispectrum features between the deception jamming and target echo are compared. Based on the results of feature analysis, the feature extraction methods applied in radar anti deception jamming are proposed and three feature factors are defined, then the feature parameters aggregate is built. Finally, the feature extraction methods are verified with simulation and real data in an actual deception jamming experiment.
2015, 44(1): 55-60.
doi: 10.3969/j.issn.1001-0548.2015.01.009
Abstract:
A general signal to clutter plus noise ratio (SCNR) model containing the partially polarized condition is created. Based on this SCNR model, a fast method for the optimization of the polarimetric contrast enhancement (OPCE) problem with constrained transmitted and received polarization is proposed. The method proves the OPCE problem equivalent to the maximization of a linear cost function. The solving of the maximization of the function is simpler than that of the OPCE problem. Hence, the faster performance searching is achieved. The method is theoretically deduced. The numerical experiments demonstrate the effectiveness of this method. Compared with the conventional global search method (GSM) based on three-step method, the proposed method costs less than 5% of the calculation time.
A general signal to clutter plus noise ratio (SCNR) model containing the partially polarized condition is created. Based on this SCNR model, a fast method for the optimization of the polarimetric contrast enhancement (OPCE) problem with constrained transmitted and received polarization is proposed. The method proves the OPCE problem equivalent to the maximization of a linear cost function. The solving of the maximization of the function is simpler than that of the OPCE problem. Hence, the faster performance searching is achieved. The method is theoretically deduced. The numerical experiments demonstrate the effectiveness of this method. Compared with the conventional global search method (GSM) based on three-step method, the proposed method costs less than 5% of the calculation time.
2015, 44(1): 61-66.
doi: 10.3969/j.issn.1001-0548.2015.01.010
Abstract:
Robotic systems suffer from different types of uncertainties which may affect the system control accuracy and even cause the system unstable. In this paper, for a class of uncertain robotic systems with external disturbance, internal dynamic parametric uncertainty and unknown dead-zone, an adaptive controller based on disturbance observer is proposed. First, the nonlinear mathematical model of robotic systems subject to external disturbance is established and the internal dynamic parametric uncertainty and unknown dead-zone in the system are analyzed. Then nonlinear disturbance observer is employed to estimate and compensate for the external disturbance. Based on the disturbance observer, an adaptive controller is then designed to deal with the uncertain dynamic parameters and unknown dead-zone. Finally, the stability and the convergence of the position tracking error of the system are proved via Lyapunov function analysis. Digital simulations demonstrate the validity of the proposed approach.
Robotic systems suffer from different types of uncertainties which may affect the system control accuracy and even cause the system unstable. In this paper, for a class of uncertain robotic systems with external disturbance, internal dynamic parametric uncertainty and unknown dead-zone, an adaptive controller based on disturbance observer is proposed. First, the nonlinear mathematical model of robotic systems subject to external disturbance is established and the internal dynamic parametric uncertainty and unknown dead-zone in the system are analyzed. Then nonlinear disturbance observer is employed to estimate and compensate for the external disturbance. Based on the disturbance observer, an adaptive controller is then designed to deal with the uncertain dynamic parameters and unknown dead-zone. Finally, the stability and the convergence of the position tracking error of the system are proved via Lyapunov function analysis. Digital simulations demonstrate the validity of the proposed approach.
2015, 44(1): 67-71.
doi: 10.3969/j.issn.1001-0548.2015.01.011
Abstract:
Peak current-mode controlled synchronous switched converter has a wide range of applications in the industrial sector because of its excellent performance. The discrete iterative map model of peak current-mode controlled synchronous switched Boost converter is established in this paper. The relationship between the first bifurcation point and the strength of the controlled voltage source is derived. The research results show that the increase in the strength of controlled voltage source can affect the bifurcation and chaotic state, which realizes the movement of periodic orbits of the system. Finally, the impact on the stability of the synchronous switched Boost converter by changing the strength of controlled voltage source is verified by the circuit simulation and the experimental study.
Peak current-mode controlled synchronous switched converter has a wide range of applications in the industrial sector because of its excellent performance. The discrete iterative map model of peak current-mode controlled synchronous switched Boost converter is established in this paper. The relationship between the first bifurcation point and the strength of the controlled voltage source is derived. The research results show that the increase in the strength of controlled voltage source can affect the bifurcation and chaotic state, which realizes the movement of periodic orbits of the system. Finally, the impact on the stability of the synchronous switched Boost converter by changing the strength of controlled voltage source is verified by the circuit simulation and the experimental study.
2015, 44(1): 72-78.
doi: 10.3969/j.issn.1001-0548.2015.01.012
Abstract:
Targeting at the problem of wrinkled Chinese handwriting recognition, this paper presents a method based on statistical characteristics of scattering transform coefficients. This method mainly uses the local translational invariance and the stability of elastic deformation of scattering transform. Firstly, the text image is transformed by scattering. The distribution characteristics used as global characteristics are extracted by applying gamma model to scattering coefficients of sub-bands. Then the copula model is constructed based on these global characteristics. Finally, the similarities are calculated for recognizing writers by using the Kullback-Leibler divergence between copula models. Theoretical analysis and comparative experiment show that our method based on statistical characteristics of scattering transform is more advantageous than the others for when regarding text images with various degrees of wrinkles.
Targeting at the problem of wrinkled Chinese handwriting recognition, this paper presents a method based on statistical characteristics of scattering transform coefficients. This method mainly uses the local translational invariance and the stability of elastic deformation of scattering transform. Firstly, the text image is transformed by scattering. The distribution characteristics used as global characteristics are extracted by applying gamma model to scattering coefficients of sub-bands. Then the copula model is constructed based on these global characteristics. Finally, the similarities are calculated for recognizing writers by using the Kullback-Leibler divergence between copula models. Theoretical analysis and comparative experiment show that our method based on statistical characteristics of scattering transform is more advantageous than the others for when regarding text images with various degrees of wrinkles.
2015, 44(1): 79-83.
doi: 10.3969/j.issn.1001-0548.2015.01.013
Abstract:
In this paper, based on the assumption that human visual system(HVS) is sensitive for image structures (edges) and local luminance (light stimulation), we propose a new perceptual image quality assessment (PIQA) metric based on total variation(TV) model in spatial domain. In the proposed metric, the TV's comparison between a distorted image and its reference image is applied to measure the extent of the loss of the image structural information. As a complementary part to measure the distortion, the energy of enclosed regions in a difference image is used to measure the missing luminance information which is sensitive to human visual system. The performance of the proposed metric is validated with an extensive subjective database. The results show that the proposed metric outperforms the state-of-the-art of image quality assessment metrics.
In this paper, based on the assumption that human visual system(HVS) is sensitive for image structures (edges) and local luminance (light stimulation), we propose a new perceptual image quality assessment (PIQA) metric based on total variation(TV) model in spatial domain. In the proposed metric, the TV's comparison between a distorted image and its reference image is applied to measure the extent of the loss of the image structural information. As a complementary part to measure the distortion, the energy of enclosed regions in a difference image is used to measure the missing luminance information which is sensitive to human visual system. The performance of the proposed metric is validated with an extensive subjective database. The results show that the proposed metric outperforms the state-of-the-art of image quality assessment metrics.
2015, 44(1): 84-90.
doi: 10.3969/j.issn.1001-0548.2015.01.014
Abstract:
A fast nonlocal means (NLM) image denoising method with selective calculation is proposed to solve the problem that the computational cost of similarity weights is high. By using L2 Norm successive elimination, a large number of pixels of low similarity van be rejected through a small amount of additive operations on integral image, and the massive calculation on measuring similarity can be effectively reduced. According to spatial coherence in the image domain, an approach for adaptive search area based on patch geodesic distance is proposed. Experimental results demonstrate that the proposed method, compared with the state-of-the-art algorithms, can not only accelerate the nonlocal means algorithm, but also elevate the image quality.
A fast nonlocal means (NLM) image denoising method with selective calculation is proposed to solve the problem that the computational cost of similarity weights is high. By using L2 Norm successive elimination, a large number of pixels of low similarity van be rejected through a small amount of additive operations on integral image, and the massive calculation on measuring similarity can be effectively reduced. According to spatial coherence in the image domain, an approach for adaptive search area based on patch geodesic distance is proposed. Experimental results demonstrate that the proposed method, compared with the state-of-the-art algorithms, can not only accelerate the nonlocal means algorithm, but also elevate the image quality.
2015, 44(1): 91-96.
doi: 10.3969/j.issn.1001-0548.2015.01.015
Abstract:
Conventional particle filters use simple geometric shapes with finite dimensional parameters to give the tracking results, therefore cannot precisely present the real-world objects with complex shapes. Aiming at this problem, this paper presents a novel particle filter based active contour algorithm for object contour tracking task. The active contour is introduced on the base of the samples simulating the target state posterior distribution; By including the weighted particles into the energy function, the contours evolve towards the region with particles with important weights and eventually converge to image region with maximum likelihood of the target. The proposed algorithm can improve the updating accuracy of the target model and avoid the tracking drift. Finally, a real-world airport surveillance application is presented to show the effectiveness and robustness of the proposed method in complex scenarios.
Conventional particle filters use simple geometric shapes with finite dimensional parameters to give the tracking results, therefore cannot precisely present the real-world objects with complex shapes. Aiming at this problem, this paper presents a novel particle filter based active contour algorithm for object contour tracking task. The active contour is introduced on the base of the samples simulating the target state posterior distribution; By including the weighted particles into the energy function, the contours evolve towards the region with particles with important weights and eventually converge to image region with maximum likelihood of the target. The proposed algorithm can improve the updating accuracy of the target model and avoid the tracking drift. Finally, a real-world airport surveillance application is presented to show the effectiveness and robustness of the proposed method in complex scenarios.
2015, 44(1): 97-100.
doi: 10.3969/j.issn.1001-0548.2015.01.016
Abstract:
In order to achieve small area implementation of encryption in resource-constrained smart cards, we studied the hardware optimal implementation of electronic product code block cipher(EPCBC) encryption algorithm. Firstly, each operation is accomplished only once, and the main program calls the 32 times to complete the encryption. Secondly, the same register is used in the S-box and key transformation so that the number of required registers is reduced. Thirdly, the cipher round operation and key update are put in the same module. Through field programmable gate array(FPGA) the experimental results show that the implementation area of EPCBC is greatly reduced, the optimization efficiency rate reaches 56%, and the encryption performance is not decreased so as to provide practical solutions for resource-constrained cryptographic smart cards.
In order to achieve small area implementation of encryption in resource-constrained smart cards, we studied the hardware optimal implementation of electronic product code block cipher(EPCBC) encryption algorithm. Firstly, each operation is accomplished only once, and the main program calls the 32 times to complete the encryption. Secondly, the same register is used in the S-box and key transformation so that the number of required registers is reduced. Thirdly, the cipher round operation and key update are put in the same module. Through field programmable gate array(FPGA) the experimental results show that the implementation area of EPCBC is greatly reduced, the optimization efficiency rate reaches 56%, and the encryption performance is not decreased so as to provide practical solutions for resource-constrained cryptographic smart cards.
2015, 44(1): 101-105.
doi: 10.3969/j.issn.1001-0548.2015.01.017
Abstract:
A leakproof multi-secret sharing scheme based on environment sensing is proposed, in which the private key generator (PKG) uses the Chinese remainder theorem to combine multi-secret into one secret, and computes the shadows through the Lagrange interpolation polynomial. In the reconstruction, the participants use the bilinear map to compute the counterfeit shadows according to the shadows and the current environment. The verifier computes the authentication information through the Lagrange interpolation and the bilinear map, and checks the validity of the counterfeit shadows. In the scheme, the shadows of participants and the shared secret are leakproof, and can be used repeatedly. The dynamic property based on environment sensing can improve the security against the mobile adversary. The proposed scheme is particularly suitable for the system which needs to run long time in the open, such as the wireless sensor network and the multi-robots, and can improve the efficiency and security of these systems effectively.
A leakproof multi-secret sharing scheme based on environment sensing is proposed, in which the private key generator (PKG) uses the Chinese remainder theorem to combine multi-secret into one secret, and computes the shadows through the Lagrange interpolation polynomial. In the reconstruction, the participants use the bilinear map to compute the counterfeit shadows according to the shadows and the current environment. The verifier computes the authentication information through the Lagrange interpolation and the bilinear map, and checks the validity of the counterfeit shadows. In the scheme, the shadows of participants and the shared secret are leakproof, and can be used repeatedly. The dynamic property based on environment sensing can improve the security against the mobile adversary. The proposed scheme is particularly suitable for the system which needs to run long time in the open, such as the wireless sensor network and the multi-robots, and can improve the efficiency and security of these systems effectively.
2015, 44(1): 106-111.
doi: 10.3969/j.issn.1001-0548.2015.01.018
Abstract:
Based on the similarity comparison of WSN model and social network model, this paper proposes a trust model based on social network correlation degree in wireless sensor networks (WSN). The computing method of WSN node credit with network correlation degree is built. The sensor node trust update algorithm (SNTUA) is designed based on sliding windows. Simulation experiments prove that SNTUA is better than other two algorithms and the correctness and effectiveness of SNTUA is testified.
Based on the similarity comparison of WSN model and social network model, this paper proposes a trust model based on social network correlation degree in wireless sensor networks (WSN). The computing method of WSN node credit with network correlation degree is built. The sensor node trust update algorithm (SNTUA) is designed based on sliding windows. Simulation experiments prove that SNTUA is better than other two algorithms and the correctness and effectiveness of SNTUA is testified.
2015, 44(1): 112-116.
doi: 10.3969/j.issn.1001-0548.2015.01.019
Abstract:
It is vitally important to generate keys and keep them secret in secure wireless communications. Due to the broadcast nature of wireless channels, secret key distribution is more vulnerable to attacks in wireless communication. An ingenious solution is to generate secret keys by using the multipath channel as a source of common randomness. To address the problems that the existing physical-based protocols have low key generation rate and high reliance on mobile nodes or environments, a fast secret key generation protocol with virtual channel approach was proposed by HUANG and WANG for static wireless networks. In this paper, we show that, in the presence of an eavesdropper with multiple antennas, the scheme does not improve the theoretical upper bound of the key generation rate with information-theory security. Thus, the protocol is not information-theory security.
It is vitally important to generate keys and keep them secret in secure wireless communications. Due to the broadcast nature of wireless channels, secret key distribution is more vulnerable to attacks in wireless communication. An ingenious solution is to generate secret keys by using the multipath channel as a source of common randomness. To address the problems that the existing physical-based protocols have low key generation rate and high reliance on mobile nodes or environments, a fast secret key generation protocol with virtual channel approach was proposed by HUANG and WANG for static wireless networks. In this paper, we show that, in the presence of an eavesdropper with multiple antennas, the scheme does not improve the theoretical upper bound of the key generation rate with information-theory security. Thus, the protocol is not information-theory security.
2015, 44(1): 117-122.
doi: 10.3969/j.issn.1001-0548.2015.01.020
Abstract:
For the kernel integrity threats of virtual machine in cloud computing environment, an integrity protecting technology of virtual machine kernel, cloud trusted virtual machine(CTVM), is proposed. In the CTVM, the virtual trusted execution environment in kernel-based virtual machine(KVM) is created, the multiple virtual machines are endowed with a trusted computing function at the same time, and the guest virtual machines are provided with integrity measurement ability. By utilizing hardware virtualization technology, the untrusted kernel modules are isolated from operating system kernel through constructing isolated address space in guest virtual machines, so as to protect the booting integrity and runtime integrity of guest virtual machines. Finally, with a domestic server as the experimental platform, CTVM prototype system is presented. System test and analysis show that the system performance loss is within the acceptable range.
For the kernel integrity threats of virtual machine in cloud computing environment, an integrity protecting technology of virtual machine kernel, cloud trusted virtual machine(CTVM), is proposed. In the CTVM, the virtual trusted execution environment in kernel-based virtual machine(KVM) is created, the multiple virtual machines are endowed with a trusted computing function at the same time, and the guest virtual machines are provided with integrity measurement ability. By utilizing hardware virtualization technology, the untrusted kernel modules are isolated from operating system kernel through constructing isolated address space in guest virtual machines, so as to protect the booting integrity and runtime integrity of guest virtual machines. Finally, with a domestic server as the experimental platform, CTVM prototype system is presented. System test and analysis show that the system performance loss is within the acceptable range.
2015, 44(1): 123-128.
doi: 10.3969/j.issn.1001-0548.2015.01.021
Abstract:
With the rapid development of wireless technology, wireless developers and users for special needs require a high-performance, customizable hardware/software(HW/SW) open platform for underlying wireless networks. This paper describes the design and implement of our proposed GRT platform, which can provide the features of high-performance, highly customizability, compatibility, and openness. As an example, we have implemented a set of SW/HW codes following 802.11a/g protocol. The system based on these codes exceeds the maximum data rate of the physical layer specified in the protocol, and can communicate with commodity WiFi devices.
With the rapid development of wireless technology, wireless developers and users for special needs require a high-performance, customizable hardware/software(HW/SW) open platform for underlying wireless networks. This paper describes the design and implement of our proposed GRT platform, which can provide the features of high-performance, highly customizability, compatibility, and openness. As an example, we have implemented a set of SW/HW codes following 802.11a/g protocol. The system based on these codes exceeds the maximum data rate of the physical layer specified in the protocol, and can communicate with commodity WiFi devices.
2015, 44(1): 129-133.
doi: 10.3969/j.issn.1001-0548.2015.01.022
Abstract:
The PDMS/MWNTs (polydimethylsiloxane/multi-walled carbon nanotubes) composite large strain sensitive materials were prepared by the physical blending technology, and the effect of the proportion on the large strain sensing properties was investigated. The sensing mechanism model was established based on the microstructures characterization. The large strain properties of PDMS composite material filled with MWNTs and graphite were preliminary explored. The results show that the PDMS/MWNTs composite material exhibits the good linear characteristic between the relative resistance rate and the large strain:the optimal strain property with the strain coefficient 3.1 can be obtained when the content of MWNTs is 9 wt%. The resistance change of the PDMS/MWNTs/graphite composite materials exhibits the nonlinear characteristics with the large strain. The analysis reveals that the mutual complementation of the remote conductive network of MWNTs and short-range conductive network of graphite forms the more stable conductive pathways and network, so as to retard the linear increase of resistance.
The PDMS/MWNTs (polydimethylsiloxane/multi-walled carbon nanotubes) composite large strain sensitive materials were prepared by the physical blending technology, and the effect of the proportion on the large strain sensing properties was investigated. The sensing mechanism model was established based on the microstructures characterization. The large strain properties of PDMS composite material filled with MWNTs and graphite were preliminary explored. The results show that the PDMS/MWNTs composite material exhibits the good linear characteristic between the relative resistance rate and the large strain:the optimal strain property with the strain coefficient 3.1 can be obtained when the content of MWNTs is 9 wt%. The resistance change of the PDMS/MWNTs/graphite composite materials exhibits the nonlinear characteristics with the large strain. The analysis reveals that the mutual complementation of the remote conductive network of MWNTs and short-range conductive network of graphite forms the more stable conductive pathways and network, so as to retard the linear increase of resistance.
2015, 44(1): 134-139.
doi: 10.3969/j.issn.1001-0548.2015.01.023
Abstract:
The contradiction between higher reverse breakdown voltage and lower conduction resistance is important for power semiconductor devices. Using Super-Junction structure as the voltage support layer can weaken this contradiction. In this paper, a super-junction Schottky barrier diode (SJ-SBD), in which a SJ structure was used as the voltage support layer, was designed and fabricated. The SJ layer which is composed of alternant P-pillar and N-pillar was formed through four times N-type epitaxy and four times P-type implant. SJ-SBD and traditional SBD With the same thickness of drift layer were implemented. And the impurity concentration of P-pillar and N-pillar in SJ layer was the same as that of the drift layer in SBD. The tested results showed that the maximum reverse breakdown voltages are 110 V for traditional SBD and 229 V for SJ-SBD. It is indicated that using the SJ structure as the drift layer could increase the reverse breakdown voltage and reduce the conduction resistance obviously. And the breakdown voltage of SJ-SBD was the maximal when total charge in N-pillar and P-pillar was equal.
The contradiction between higher reverse breakdown voltage and lower conduction resistance is important for power semiconductor devices. Using Super-Junction structure as the voltage support layer can weaken this contradiction. In this paper, a super-junction Schottky barrier diode (SJ-SBD), in which a SJ structure was used as the voltage support layer, was designed and fabricated. The SJ layer which is composed of alternant P-pillar and N-pillar was formed through four times N-type epitaxy and four times P-type implant. SJ-SBD and traditional SBD With the same thickness of drift layer were implemented. And the impurity concentration of P-pillar and N-pillar in SJ layer was the same as that of the drift layer in SBD. The tested results showed that the maximum reverse breakdown voltages are 110 V for traditional SBD and 229 V for SJ-SBD. It is indicated that using the SJ structure as the drift layer could increase the reverse breakdown voltage and reduce the conduction resistance obviously. And the breakdown voltage of SJ-SBD was the maximal when total charge in N-pillar and P-pillar was equal.
2015, 44(1): 140-146.
doi: 10.3969/j.issn.1001-0548.2015.01.024
Abstract:
SO42-/ZrO2-Nd2O3 solid acid was prepared by using collagen fibers as template, zirconium sulfate as zirconium source and doping with rare earth element Nd. The as-prepared SO42-/ZrO2-Nd2O3 were characterized by TG, XRD, FT-IR、SEM and N2 adsorption-desorption analysis so as to investigate the influence of preparation conditions on the catalyst structure. The results reveal that the fibrous structures of collagen fibers are preserved in the SO42-/ZrO2-Nd2O3 solid acid. The growth of the ZrO2-Nd2O3 particles can be efficiently suppressed by Nd doping. The diameters of ZrO2-Nd2O3 particles are distributed in the range of 5.1~11.6 nm. The BET surface area of SO42-/ZrO2-Nd2O3 solid acid is 63.96 m2/g. The esterification of acetic acid with n-butanol was carried out as a model reaction to calculate the catalytic properties of SO42-/ZrO2-Nd2O3 solid acid. The SO42-/ZrO2-Nd2O3 solid acid exhibits high catalytic activity. Furthermore, the conversion rate of acetic acid can reach 85% in the fifth cycle, which showsthe satisfied reusability, thus showing a potential industrial application.
SO42-/ZrO2-Nd2O3 solid acid was prepared by using collagen fibers as template, zirconium sulfate as zirconium source and doping with rare earth element Nd. The as-prepared SO42-/ZrO2-Nd2O3 were characterized by TG, XRD, FT-IR、SEM and N2 adsorption-desorption analysis so as to investigate the influence of preparation conditions on the catalyst structure. The results reveal that the fibrous structures of collagen fibers are preserved in the SO42-/ZrO2-Nd2O3 solid acid. The growth of the ZrO2-Nd2O3 particles can be efficiently suppressed by Nd doping. The diameters of ZrO2-Nd2O3 particles are distributed in the range of 5.1~11.6 nm. The BET surface area of SO42-/ZrO2-Nd2O3 solid acid is 63.96 m2/g. The esterification of acetic acid with n-butanol was carried out as a model reaction to calculate the catalytic properties of SO42-/ZrO2-Nd2O3 solid acid. The SO42-/ZrO2-Nd2O3 solid acid exhibits high catalytic activity. Furthermore, the conversion rate of acetic acid can reach 85% in the fifth cycle, which showsthe satisfied reusability, thus showing a potential industrial application.
2015, 44(1): 147-149.
doi: 10.3969/j.issn.1001-0548.2015.01.025
Abstract:
By analyzing the 168 experimental-confirmed σ54 promoter sequences, two conservative regions that are -24 and -12 regions are obtained. The trimer frequency at 17 positions in these conservative regions is selected as inputting parameter. By adding pseudo-count into position weight matrix, the σ54 promoter can be predicted. The 168 negative sequences are extracted from coding regions and convergent intergenic regions. In Jackknife cross-validation, the overall accuracy reaches to 82.0%, suggesting that the model can be further used in the theoretical and experimental study of σ54 promoter.
By analyzing the 168 experimental-confirmed σ54 promoter sequences, two conservative regions that are -24 and -12 regions are obtained. The trimer frequency at 17 positions in these conservative regions is selected as inputting parameter. By adding pseudo-count into position weight matrix, the σ54 promoter can be predicted. The 168 negative sequences are extracted from coding regions and convergent intergenic regions. In Jackknife cross-validation, the overall accuracy reaches to 82.0%, suggesting that the model can be further used in the theoretical and experimental study of σ54 promoter.
2015, 44(1): 150-154.
doi: 10.3969/j.issn.1001-0548.2015.01.026
Abstract:
Magneto-acousto-electrical tomography (MAET), which combines the electrical impedance tomography with high contrast and the ultrasound imaging with good spatial resolution, is a novel medical imaging method to obtain high quality images of biological electrical impedance imaging. In this paper, a mathematical model of 2D MAET forward problem and inverse problem is established and derived with reciprocity theorem. On this basis, the current density and conductivity distribution of 2D physical model sample are reconstructed. Finally, the imaging influence factors of focal spot size and scan step for ultrasound probe are analyzed. The analysis shows that the focal spot size determines the lateral resolution of MAET imaging, and the scanning step affects the image quality to some extent.
Magneto-acousto-electrical tomography (MAET), which combines the electrical impedance tomography with high contrast and the ultrasound imaging with good spatial resolution, is a novel medical imaging method to obtain high quality images of biological electrical impedance imaging. In this paper, a mathematical model of 2D MAET forward problem and inverse problem is established and derived with reciprocity theorem. On this basis, the current density and conductivity distribution of 2D physical model sample are reconstructed. Finally, the imaging influence factors of focal spot size and scan step for ultrasound probe are analyzed. The analysis shows that the focal spot size determines the lateral resolution of MAET imaging, and the scanning step affects the image quality to some extent.
2015, 44(1): 155-160.
doi: 10.3969/j.issn.1001-0548.2015.01.027
Abstract:
Insulin detection is significant in clinical study, but the lack of effective detection methods impedes its clinical applications. In this work, the carbon microelectrode fabricated with MEMS (micro-electromechanical system) and C-MEMS (complex micro-electromechanical system) technology is applied for insulin detection. The carbon microelectrodes were fabricated through the pyrolysis of photoresist and showed good electrochemical performance. After electro-deposition of ruthinium oxide nano particles on the electrode surface, the insulin oxidation is electro-catalyzed and its electrochemical detection is realized at 0.7 V. The sensor has a sensitivity of 1 nA/μM for insulin detection, with a detection limit of 800 nM. Electrochemical measurement shows that the sensor has advantages of high sensitivity, fast response and usability for real time on-site detection.
Insulin detection is significant in clinical study, but the lack of effective detection methods impedes its clinical applications. In this work, the carbon microelectrode fabricated with MEMS (micro-electromechanical system) and C-MEMS (complex micro-electromechanical system) technology is applied for insulin detection. The carbon microelectrodes were fabricated through the pyrolysis of photoresist and showed good electrochemical performance. After electro-deposition of ruthinium oxide nano particles on the electrode surface, the insulin oxidation is electro-catalyzed and its electrochemical detection is realized at 0.7 V. The sensor has a sensitivity of 1 nA/μM for insulin detection, with a detection limit of 800 nM. Electrochemical measurement shows that the sensor has advantages of high sensitivity, fast response and usability for real time on-site detection.
