ISSN 
2014 Vol. 43, No. 6
2014, 43(6): 801-806.
doi: 10.3969/j.issn.1001-0548.2014.06.001
Abstract:
The high peak-to-average power ratio (PAPR) is the bottleneck of the development of multicarrier transmission technology. The residue number system (RNS)-based PAPR reduction method is proposed to improve PAPR performance. The main idea of the proposed method is to use the parallel and modular operation properties of RNS to limit the dynamic range of transmitted signals for PAPR reduction. In this paper, the performance of the proposed method is analyzed. In addition, the common lossless methods, selective mapping (SLM) and partial transmit sequences (PTS), are compared with the proposed method. Theoretical analysis and simulation results demonstrate the proposed method has the capability to achieve desirable PAPR reduction and low complexity without distortion and side information, compared with PTS and SLM.
The high peak-to-average power ratio (PAPR) is the bottleneck of the development of multicarrier transmission technology. The residue number system (RNS)-based PAPR reduction method is proposed to improve PAPR performance. The main idea of the proposed method is to use the parallel and modular operation properties of RNS to limit the dynamic range of transmitted signals for PAPR reduction. In this paper, the performance of the proposed method is analyzed. In addition, the common lossless methods, selective mapping (SLM) and partial transmit sequences (PTS), are compared with the proposed method. Theoretical analysis and simulation results demonstrate the proposed method has the capability to achieve desirable PAPR reduction and low complexity without distortion and side information, compared with PTS and SLM.
2014, 43(6): 807-812.
Abstract:
In cooperative communications systems, allocating relay rationally is significant to promote the performance. However, the existing relay assignment methods only trend to maximize the capacity or the minimum transmission power, lack the comprehensive consideration of both capacity and transmission power so that the result of assignment is not the optimal. A relay allocation algorithm, called energy efficiency aware relay assignment algorithm (EERAA), is proposed with the objective of maximizing energy efficiency (ratio of capacity and transmission power). Firstly, EERAA algorithm optimizes the energy efficiency of collaboration link. Then, according to the result of maximum weight matching method. The base station allocates the optimal relay to source node, or source node communicating with base station directly. The simulation results verify that the energy efficiency of the proposed algorithm achieves a significant improvement compared with the existing methods.
In cooperative communications systems, allocating relay rationally is significant to promote the performance. However, the existing relay assignment methods only trend to maximize the capacity or the minimum transmission power, lack the comprehensive consideration of both capacity and transmission power so that the result of assignment is not the optimal. A relay allocation algorithm, called energy efficiency aware relay assignment algorithm (EERAA), is proposed with the objective of maximizing energy efficiency (ratio of capacity and transmission power). Firstly, EERAA algorithm optimizes the energy efficiency of collaboration link. Then, according to the result of maximum weight matching method. The base station allocates the optimal relay to source node, or source node communicating with base station directly. The simulation results verify that the energy efficiency of the proposed algorithm achieves a significant improvement compared with the existing methods.
2014, 43(6): 813-816,828.
doi: 10.3969/j.issn.1001-0548.2014.06.003
Abstract:
In the current collaborative sparse unmixing of hyperspectral data, the fractional abundances can not be estimated accurately due to ignoring the differences of endmembers among different pixels. In this paper, a novel unsupervised clustering method is proposed as a preprocessing step to generate several classes of pixels with the same endmember bundles, and then for each class, the collaborative sparse unmixing technique is used to implement spectral unmixing. In terms that the pixels with the same set of active atoms have the smallest values of collaborative sparse coding, the sum of reconstruction errors and sparsity levels are introduced as the distance metric in the unsupervised clustering. As such, the same class pixels can be guaranteed to contain the same endmembers. Finally, the involving optimization problem can be solved by using the algorithm of alternating direction method of multipliers (ADMM). Experimental results on synthetic and real hyperspectral data demonstrate that the our proposed algorithm can identify the actual endmembers effectively and improve the accuracy of the fractional abundance estimation.
In the current collaborative sparse unmixing of hyperspectral data, the fractional abundances can not be estimated accurately due to ignoring the differences of endmembers among different pixels. In this paper, a novel unsupervised clustering method is proposed as a preprocessing step to generate several classes of pixels with the same endmember bundles, and then for each class, the collaborative sparse unmixing technique is used to implement spectral unmixing. In terms that the pixels with the same set of active atoms have the smallest values of collaborative sparse coding, the sum of reconstruction errors and sparsity levels are introduced as the distance metric in the unsupervised clustering. As such, the same class pixels can be guaranteed to contain the same endmembers. Finally, the involving optimization problem can be solved by using the algorithm of alternating direction method of multipliers (ADMM). Experimental results on synthetic and real hyperspectral data demonstrate that the our proposed algorithm can identify the actual endmembers effectively and improve the accuracy of the fractional abundance estimation.
2014, 43(6): 817-822.
doi: 10.3969/j.issn.1001-0548.2014.06.004
Abstract:
In order to rationally assign and utilize wireless channel resources, various multi-radio and multi-channel channel assignment algorithms for wireless Mesh network have been proposed. In this paper, an improved algorithm based on connected low interference channel assignment (CLICA) is presented to improve network capacity (throughput). The interference measure of each unit in the network is calculated based on the level of interference of each link in the network. The throughput of the network is improved by reducing the network interference level. The optimal channel assignment can be achieved by using mathematical optimization model of the channel assignment.
In order to rationally assign and utilize wireless channel resources, various multi-radio and multi-channel channel assignment algorithms for wireless Mesh network have been proposed. In this paper, an improved algorithm based on connected low interference channel assignment (CLICA) is presented to improve network capacity (throughput). The interference measure of each unit in the network is calculated based on the level of interference of each link in the network. The throughput of the network is improved by reducing the network interference level. The optimal channel assignment can be achieved by using mathematical optimization model of the channel assignment.
2014, 43(6): 823-828.
doi: 10.3969/j.issn.1001-0548.2014.06.005
Abstract:
The Avionic oriented Fibre Channel network is a real-time and deterministic communication network. Optical network with wavelength division multiplexing (WDM) transmission technology has been targeted as the technology of choice to realize the desired avionic network of the future due to its lightness, high-capacity and transparency to multi-protocols. Based on the trend towards avionic network, we propose a fiber channel (FC) over WDM architecture on avionic network. The delay deterministic of FC and the bandwidth extensibility of WDM are integrated to satisfy the communication requirements of avionic network, and the existing avionics FC network can be seamlessly upgraded. We establish an FC over WDM ground experimental environment based on independently developed FC emulator, and the experimental results on functional verification and system performance analysis indicate that the adoption of WDM and optical switching in avionics fiber-optic network is feasible.
The Avionic oriented Fibre Channel network is a real-time and deterministic communication network. Optical network with wavelength division multiplexing (WDM) transmission technology has been targeted as the technology of choice to realize the desired avionic network of the future due to its lightness, high-capacity and transparency to multi-protocols. Based on the trend towards avionic network, we propose a fiber channel (FC) over WDM architecture on avionic network. The delay deterministic of FC and the bandwidth extensibility of WDM are integrated to satisfy the communication requirements of avionic network, and the existing avionics FC network can be seamlessly upgraded. We establish an FC over WDM ground experimental environment based on independently developed FC emulator, and the experimental results on functional verification and system performance analysis indicate that the adoption of WDM and optical switching in avionics fiber-optic network is feasible.
2014, 43(6): 829-833.
doi: 10.3969/j.issn.1001-0548.2014.06.006
Abstract:
A novel planar inverted-F antenna (PIFA) with dual-shorting point is proposed for multiband mobile communication applications. The antenna comprises a main strip, a parasitic strip, and a slotted ground plane. For enhancing the bandwidth of DCS/PCS/UMTS and LTE 2 300/2 500, the antenna applies dual-shorting point design to generate multimode between 1 707~2815 MHz. The antenna upper band is formed by the higher-order resonant mode contributed by the parasitic strip and can cover the desired 3387~3627 MHz. The proposed antenna has good impedance matching characteristics for GSM (824~960 MHz)/DCS (1 710~1 880 MHz)/PCS (1 850~1 990 MHz)/UMTS (1 920~2 170 MHz)/LTE (2 300~2 400 MHz, 2 500~2 690 MHz)/802.11b (2.4~2.48 GHz) and Wi-MAX (3.4~3.6 GHz). The measured radiation efficiency of proposed antenna is higher than 52% in GSM 850/900, DCS/PCS, UMTS, LTE 2 300/2 500, and IEEE 802.11 b, and is up to 50% in Wi-MAX.
A novel planar inverted-F antenna (PIFA) with dual-shorting point is proposed for multiband mobile communication applications. The antenna comprises a main strip, a parasitic strip, and a slotted ground plane. For enhancing the bandwidth of DCS/PCS/UMTS and LTE 2 300/2 500, the antenna applies dual-shorting point design to generate multimode between 1 707~2815 MHz. The antenna upper band is formed by the higher-order resonant mode contributed by the parasitic strip and can cover the desired 3387~3627 MHz. The proposed antenna has good impedance matching characteristics for GSM (824~960 MHz)/DCS (1 710~1 880 MHz)/PCS (1 850~1 990 MHz)/UMTS (1 920~2 170 MHz)/LTE (2 300~2 400 MHz, 2 500~2 690 MHz)/802.11b (2.4~2.48 GHz) and Wi-MAX (3.4~3.6 GHz). The measured radiation efficiency of proposed antenna is higher than 52% in GSM 850/900, DCS/PCS, UMTS, LTE 2 300/2 500, and IEEE 802.11 b, and is up to 50% in Wi-MAX.
2014, 43(6): 834-837.
doi: 10.3969/j.issn.1001-0548.2014.06.007
Abstract:
Traditional cross-location method uses the tangent of direction of arrival (DOA) as slope to obtain a least square solution by solving a linear equation. Generally, using the tangent of DOA as slope makes the direction indistinct in 180o. If the measurement error of the DOA is low, traditional cross-location method performs well, and the direction indistinct in 180o has little influence on the result of the algorithm. But once we deal with a large measurement error situation, the direction indistinct in 180o will import additional prominent error, which will have big influence on the precision of location. Therefore, this article proposes a new method which uses the sine and cosine of the DOAs to form the cross-location equations, subject to the constraint of the positive distance to find a solution. This method has no direction indistinct in 180o and improves the precision of the location result. The simulation result by the computer verified the fact that the new proposed method has a better location result than the traditional method under large measurement error.
Traditional cross-location method uses the tangent of direction of arrival (DOA) as slope to obtain a least square solution by solving a linear equation. Generally, using the tangent of DOA as slope makes the direction indistinct in 180o. If the measurement error of the DOA is low, traditional cross-location method performs well, and the direction indistinct in 180o has little influence on the result of the algorithm. But once we deal with a large measurement error situation, the direction indistinct in 180o will import additional prominent error, which will have big influence on the precision of location. Therefore, this article proposes a new method which uses the sine and cosine of the DOAs to form the cross-location equations, subject to the constraint of the positive distance to find a solution. This method has no direction indistinct in 180o and improves the precision of the location result. The simulation result by the computer verified the fact that the new proposed method has a better location result than the traditional method under large measurement error.
2014, 43(6): 838-844.
doi: 10.3969/j.issn.1001-0548.2014.06.008
Abstract:
Near-space slow SAR (NSS-SAR) has several advantages such as robust survivability, persistence and flexible maneuvering performance. This paper proposes a NSS-SAR ground moving target detection and imaging method. Since the platform has a slow speed, it is beneficial to separate ground static clutter and ground moving target echo separation. First, Doppler filter is used to separate the spectrum of ground moving target echo from the spectrum of static clutter. After the echo of ground moving target is extracted, first-order Keystone transform and Doppler rate estimation method are combined to accomplish range walk correction and range curvature correction, though motion parameters of ground moving target are unknown. Thus, it provides an approach to solving the difficult problem of correcting range migration of moving target echo. Then, the estimated Doppler rate is used to design azimuth compression function to achieve azimuth focusing. The proposed method is not only suitable for ground slow-moving targets but also fast-moving targets. Computer simulations verify the effectiveness of this method.
Near-space slow SAR (NSS-SAR) has several advantages such as robust survivability, persistence and flexible maneuvering performance. This paper proposes a NSS-SAR ground moving target detection and imaging method. Since the platform has a slow speed, it is beneficial to separate ground static clutter and ground moving target echo separation. First, Doppler filter is used to separate the spectrum of ground moving target echo from the spectrum of static clutter. After the echo of ground moving target is extracted, first-order Keystone transform and Doppler rate estimation method are combined to accomplish range walk correction and range curvature correction, though motion parameters of ground moving target are unknown. Thus, it provides an approach to solving the difficult problem of correcting range migration of moving target echo. Then, the estimated Doppler rate is used to design azimuth compression function to achieve azimuth focusing. The proposed method is not only suitable for ground slow-moving targets but also fast-moving targets. Computer simulations verify the effectiveness of this method.
2014, 43(6): 845-849.
doi: 10.3969/j.issn.1001-0548.2014.06.009
Abstract:
Meminductor, extended from the notion of memristor, is a novel nonlinear circuit element with memory function. Based on the model of meminductor approximate equivalent circuit and by utilizing an active flux-controlled memristor to realize the memristor in the equivalent circuit, a state equation set of the meminductor approximate equivalent circuit is established. With the help of MATLAB mathematical tool software, the properties of the equivalent meminductor are analyzed numerically. The results indicate that the flux-current relations of the equivalent meminductor typically behave as a pinched hysteresis loop characteristics and depend on the frequencies of applied voltage stimulus. By using the equivalent circuit of active flux-controlled memristor, the experimental verification for meminductor approximate equivalent circuit is performed. The experimental measurement results agree essentially with numerical simulation results, which illustrate that the model of meminductor approximate equivalent circuit is effective.
Meminductor, extended from the notion of memristor, is a novel nonlinear circuit element with memory function. Based on the model of meminductor approximate equivalent circuit and by utilizing an active flux-controlled memristor to realize the memristor in the equivalent circuit, a state equation set of the meminductor approximate equivalent circuit is established. With the help of MATLAB mathematical tool software, the properties of the equivalent meminductor are analyzed numerically. The results indicate that the flux-current relations of the equivalent meminductor typically behave as a pinched hysteresis loop characteristics and depend on the frequencies of applied voltage stimulus. By using the equivalent circuit of active flux-controlled memristor, the experimental verification for meminductor approximate equivalent circuit is performed. The experimental measurement results agree essentially with numerical simulation results, which illustrate that the model of meminductor approximate equivalent circuit is effective.
2014, 43(6): 850-856.
doi: 10.3969/j.issn.1001-0548.2014.06.010
Abstract:
This paper presents a scheme that the two-input BUCK (TIBUCK) converter is applied to the LED drivers. The performance characteristics of the circuit are analyzed in detail. The TIBUCK converter is designed to operate in the voltage control mode governed by DSP, thus the output current can be adjusted well and the LEDs can then work in the constant current mode. The simulation and experimental results show that the voltage stress of switch and diode in the TIBUCK converter are reduced, and the constant current control for the output current is realized at the same time. Thereby, as the constant-current part of the LED driver, the feasible of the TIBUCK converter is proved.
This paper presents a scheme that the two-input BUCK (TIBUCK) converter is applied to the LED drivers. The performance characteristics of the circuit are analyzed in detail. The TIBUCK converter is designed to operate in the voltage control mode governed by DSP, thus the output current can be adjusted well and the LEDs can then work in the constant current mode. The simulation and experimental results show that the voltage stress of switch and diode in the TIBUCK converter are reduced, and the constant current control for the output current is realized at the same time. Thereby, as the constant-current part of the LED driver, the feasible of the TIBUCK converter is proved.
2014, 43(6): 857-862.
doi: 10.3969/j.issn.1001-0548.2014.06.011
Abstract:
Multifrequency control method, a novel control method for switching converters, is proposed and investigated in this paper. The control pulse with different frequency which is determined according to the voltage intervals of the sampled output voltage at the end of previous switching period is applied to regulate the output voltage. In contrast to bifrequency control, the multifrequency control not only extends the output power range, but also reduces the output voltage ripple; it has merit of simple control algorithm, strong stability, fast dynamic response, low electromagnetic interference (EMI) noise, and high efficiency at light load. Experimental results demonstrate the correctness of the theoretical analyses.
Multifrequency control method, a novel control method for switching converters, is proposed and investigated in this paper. The control pulse with different frequency which is determined according to the voltage intervals of the sampled output voltage at the end of previous switching period is applied to regulate the output voltage. In contrast to bifrequency control, the multifrequency control not only extends the output power range, but also reduces the output voltage ripple; it has merit of simple control algorithm, strong stability, fast dynamic response, low electromagnetic interference (EMI) noise, and high efficiency at light load. Experimental results demonstrate the correctness of the theoretical analyses.
2014, 43(6): 863-868.
doi: 10.3969/j.issn.1001-0548.2014.06.012
Abstract:
In this paper, an anti mode mixing empirical mode decomposition (EMD) composite algorithm is proposed. First, the improved frequency heterodyne method is addressed to increase the spectral distance between mode mixing components in order to isolate the octave mode mixing components. Second, the wavelet singularity detection technology is applied to determine the adaptive sliding analysis window for each mode and then implement the intermittent mixing modes separation and their nonstationary parameters identification. In order to verify the validity of the algorithm, a test case and a grid simulation case are used to test and analyze the EMD composite algorithm. The analysis result shows that the proposed algorithm can isolate the mode mixing component effectively. Moreover, for a low frequency oscillation signal with complex modes, the proposed algorithm is able to isolate the corresponding low frequency oscillation mode and has high detection accuracy of oscillation mode information.
In this paper, an anti mode mixing empirical mode decomposition (EMD) composite algorithm is proposed. First, the improved frequency heterodyne method is addressed to increase the spectral distance between mode mixing components in order to isolate the octave mode mixing components. Second, the wavelet singularity detection technology is applied to determine the adaptive sliding analysis window for each mode and then implement the intermittent mixing modes separation and their nonstationary parameters identification. In order to verify the validity of the algorithm, a test case and a grid simulation case are used to test and analyze the EMD composite algorithm. The analysis result shows that the proposed algorithm can isolate the mode mixing component effectively. Moreover, for a low frequency oscillation signal with complex modes, the proposed algorithm is able to isolate the corresponding low frequency oscillation mode and has high detection accuracy of oscillation mode information.
2014, 43(6): 869-873.
doi: 10.3969/j.issn.1001-0548.2014.06.013
Abstract:
Signal-to-noise ratio (SNR) is a key parameter to evaluate the detection performance for a remote sensing system. A mathematical model to estimate the SNR uncertainty for aviation multi-angular polarimetric radiometer (AMPR) is proposed through analyzing the working principle of AMPR and discussing the SNRs of measured Stokes vectors and degree of polarization. Based on the proposed model, the AMPR SNR uncertainty has been validated in laboratory by using integrating sphere source. The experiment results indicate that the SNR uncertainty of AMPR is no more than 10% or 5% (1σ) for the degree of polarization less than 1% or 2%, respectively.
Signal-to-noise ratio (SNR) is a key parameter to evaluate the detection performance for a remote sensing system. A mathematical model to estimate the SNR uncertainty for aviation multi-angular polarimetric radiometer (AMPR) is proposed through analyzing the working principle of AMPR and discussing the SNRs of measured Stokes vectors and degree of polarization. Based on the proposed model, the AMPR SNR uncertainty has been validated in laboratory by using integrating sphere source. The experiment results indicate that the SNR uncertainty of AMPR is no more than 10% or 5% (1σ) for the degree of polarization less than 1% or 2%, respectively.
2014, 43(6): 874-880.
doi: 10.3969/j.issn.1001-0548.2014.06.014
Abstract:
To reduce the invalid iterations (the iteration in which the global optimum position is unchanged) of the particle swarm while solving the high-dimensional nonlinear problems by the standard particle swarm optimization (PSO) algorithm, an improved PSO algorithm with adaptive inertia weight is proposed in this paper. Based on the analysis of the instantaneous movement of single particle at each iteration, a significant argument is given and proved. In the improved algorithm, the inertia weights of the particles whose fitness become worse at the last iterations are set to zero. Six benchmark functions were used to test the proposed improved PSO algorithm, the standard PSO algorithm, the fixed inertia weight PSO algorithm, and the PSO algorithm with the leader. Experiments show that the invalid iterations of the proposed algorithm are less and it has obvious superiority on the convergence ratio, the convergence speed, and the convergence stability.
To reduce the invalid iterations (the iteration in which the global optimum position is unchanged) of the particle swarm while solving the high-dimensional nonlinear problems by the standard particle swarm optimization (PSO) algorithm, an improved PSO algorithm with adaptive inertia weight is proposed in this paper. Based on the analysis of the instantaneous movement of single particle at each iteration, a significant argument is given and proved. In the improved algorithm, the inertia weights of the particles whose fitness become worse at the last iterations are set to zero. Six benchmark functions were used to test the proposed improved PSO algorithm, the standard PSO algorithm, the fixed inertia weight PSO algorithm, and the PSO algorithm with the leader. Experiments show that the invalid iterations of the proposed algorithm are less and it has obvious superiority on the convergence ratio, the convergence speed, and the convergence stability.
2014, 43(6): 881-886.
doi: 10.3969/j.issn.1001-0548.2014.06.015
Abstract:
In order to solve the semantic gap problem between virtual machine monitor (VMM) and guest virtual machine (VM), an up-call mechanism is proposed, with which the service request is launched by VMM, and the guest-VM is responsible to provide response to the request from VMM. This makes it possible for VMM to synchronously call guest-VM services to get guest semantic information, bringing convenience for monitor agents constructed out of guest-VM address space to get guest information exactly. The up-call mechanism implemented as a synchronous communication channel is able to make up the problem of duplicate definitions and implementations inside VMM brought by semantic reconstruction. A prototype system on the para-virtualization platform of Xen is implemented. The result shows that the method proposed in this paper is able to help VMM to call guest functions to get guest services and semantic information instantly.
In order to solve the semantic gap problem between virtual machine monitor (VMM) and guest virtual machine (VM), an up-call mechanism is proposed, with which the service request is launched by VMM, and the guest-VM is responsible to provide response to the request from VMM. This makes it possible for VMM to synchronously call guest-VM services to get guest semantic information, bringing convenience for monitor agents constructed out of guest-VM address space to get guest information exactly. The up-call mechanism implemented as a synchronous communication channel is able to make up the problem of duplicate definitions and implementations inside VMM brought by semantic reconstruction. A prototype system on the para-virtualization platform of Xen is implemented. The result shows that the method proposed in this paper is able to help VMM to call guest functions to get guest services and semantic information instantly.
2014, 43(6): 887-892.
doi: 10.3969/j.issn.1001-0548.2014.06.016
Abstract:
A link-based fuzzy cluster ensemble (LBFCE) is proposed to solve the problem that many clustering ensemble methods ignore the underlying information or acquire the underlying information by complex approaches. In the LBFCE, an ensemble information matrix is first built by primarily exploiting the results of fuzzy clustering, this matrix is then transformed into a weighted graph with data relations by appropriate link analysis, and at last a graph partitioning algorithm is employed to get the final clustering results. Experimental results show that the LBFCE algorithm may obtain the underlying information effectively and improve clustering performance.
A link-based fuzzy cluster ensemble (LBFCE) is proposed to solve the problem that many clustering ensemble methods ignore the underlying information or acquire the underlying information by complex approaches. In the LBFCE, an ensemble information matrix is first built by primarily exploiting the results of fuzzy clustering, this matrix is then transformed into a weighted graph with data relations by appropriate link analysis, and at last a graph partitioning algorithm is employed to get the final clustering results. Experimental results show that the LBFCE algorithm may obtain the underlying information effectively and improve clustering performance.
2014, 43(6): 893-897.
doi: 10.3969/j.issn.1001-0548.2014.06.017
Abstract:
In order to find the true values in master data integration and web data integration, we propose a true value finding algorithm (FA-SDCM) based on a support degree calculation model using fuzzy partial order relations. In existing algorithms, support degrees are usually substituted by similarity, which ignores the asymmetry in the true vales. In this paper, the concept of description containing is proposed through analyzing characteristics of descriptions, and then a support degree calculating model is developed based on fuzzy partial order relations to solve the description of asymmetric problems in the true values. Considering the influence of the data source reliability and the support degrees among descriptions on true value finding, the FA-SDCM algorithm is realized iteratively. An experiment has been carried on the Books-Authors data set, and the result shows that the FA-SDCM algorithm has better accuracy than the Vote and the TruthFinder algorithms.
In order to find the true values in master data integration and web data integration, we propose a true value finding algorithm (FA-SDCM) based on a support degree calculation model using fuzzy partial order relations. In existing algorithms, support degrees are usually substituted by similarity, which ignores the asymmetry in the true vales. In this paper, the concept of description containing is proposed through analyzing characteristics of descriptions, and then a support degree calculating model is developed based on fuzzy partial order relations to solve the description of asymmetric problems in the true values. Considering the influence of the data source reliability and the support degrees among descriptions on true value finding, the FA-SDCM algorithm is realized iteratively. An experiment has been carried on the Books-Authors data set, and the result shows that the FA-SDCM algorithm has better accuracy than the Vote and the TruthFinder algorithms.
2014, 43(6): 898-903.
doi: 10.3969/j.issn.1001-0548.2014.06.018
Abstract:
The traditional community discovery algorithms are generally based on the link structure of a given social network, they lack of consideration of user's interests and the hierarchical structure of community. In this paper, a novel PAM (Pachinko Allocation Model) probabilistic generative model is proposed to detect latent hierarchical communities based on the user interests and their social relationships. The joint model of topic modeling and community discovery can capture the correlation among multiple communities and their hierarchical structure. Experiments on real-world dataset have confirmed the feasibility and effectiveness of the proposed algorithm.
The traditional community discovery algorithms are generally based on the link structure of a given social network, they lack of consideration of user's interests and the hierarchical structure of community. In this paper, a novel PAM (Pachinko Allocation Model) probabilistic generative model is proposed to detect latent hierarchical communities based on the user interests and their social relationships. The joint model of topic modeling and community discovery can capture the correlation among multiple communities and their hierarchical structure. Experiments on real-world dataset have confirmed the feasibility and effectiveness of the proposed algorithm.
2014, 43(6): 904-909.
doi: 10.3969/j.issn.1001-0548.2014.06.019
Abstract:
In three-dimensional (3D) human motion tracking from monocular video sequences, twodimensional (2D) body template cannot register accurately due to occlusion, which lead to track fail. To overcome this problem, a 3D texture model is used to track human motion. First, the template of the texture model and the local coordinates of each pixel under straight pose are initialized in the first frame. Then, the human motion is optimized by the pixel intensity consistency constraint, and a new 2D template is obtained by the tracked result. To contain the latest body information, the oldest template in the collection is dumped while a new template arrives, and the finally tracking result is determined by the output of template with the highest similarity. The experimental results demonstrate that the proposed algorithm is more effective in solving occlusion caused by segment self-rotation than the single 2D template matching method.
In three-dimensional (3D) human motion tracking from monocular video sequences, twodimensional (2D) body template cannot register accurately due to occlusion, which lead to track fail. To overcome this problem, a 3D texture model is used to track human motion. First, the template of the texture model and the local coordinates of each pixel under straight pose are initialized in the first frame. Then, the human motion is optimized by the pixel intensity consistency constraint, and a new 2D template is obtained by the tracked result. To contain the latest body information, the oldest template in the collection is dumped while a new template arrives, and the finally tracking result is determined by the output of template with the highest similarity. The experimental results demonstrate that the proposed algorithm is more effective in solving occlusion caused by segment self-rotation than the single 2D template matching method.
2014, 43(6): 910-916.
doi: 10.3969/j.issn.1001-0548.2014.06.020
Abstract:
Since classical morphological gradient operator cannot be directly extended to color image processing, the existing vector morphological gradient operator is sensitive to noise and it has low performance. This paper proposes a new soft vector morphological gradient operator and applies it in the edge detection of color images in order to solve the problem. New morphological gradient operator takes the advantage of soft morphology theory, which effectively reduces the influence of noise on the edge, so as to improve the anti-interference ability of the vector morphological gradient operator. Experimental results show that compared with the existing vector morphological gradient operators, the new soft vector morphology gradient operators achieve better gradient vector in the case of noise, and plays an important role in the following steps of color image segmentation and recognition.
Since classical morphological gradient operator cannot be directly extended to color image processing, the existing vector morphological gradient operator is sensitive to noise and it has low performance. This paper proposes a new soft vector morphological gradient operator and applies it in the edge detection of color images in order to solve the problem. New morphological gradient operator takes the advantage of soft morphology theory, which effectively reduces the influence of noise on the edge, so as to improve the anti-interference ability of the vector morphological gradient operator. Experimental results show that compared with the existing vector morphological gradient operators, the new soft vector morphology gradient operators achieve better gradient vector in the case of noise, and plays an important role in the following steps of color image segmentation and recognition.
2014, 43(6): 917-922.
doi: 10.3969/j.issn.1001-0548.2014.06.021
Abstract:
Recently the attack strategy has become a hot topic to study the robustness against cascading failures in complex networks. Considering a node's initial load and the average degree of the neighboring nodes, we propose a new attack strategy, neighbor-nodes average degree (NAD), and analyze the correlation between the critical threshold TC and tunable parameter α. By comparing the two attack strategies on the nodes with the highest load and the lowest load, we find that the proposed attack strategy is an efficient way to destruct the BA scale-free networks in the range of α. In addition, on the base of the model of BA-BA coupled networks, the preliminary numerical simulation on the proposed attack strategy verifies the mathematic analysis of the targeted-attack to random-attack. By creating a model of the correlated coupled networks for the emergency, we can investigate the condition on cascading failure for the model and propose a protective strategy for preventing avalanche of coupled networks.
Recently the attack strategy has become a hot topic to study the robustness against cascading failures in complex networks. Considering a node's initial load and the average degree of the neighboring nodes, we propose a new attack strategy, neighbor-nodes average degree (NAD), and analyze the correlation between the critical threshold TC and tunable parameter α. By comparing the two attack strategies on the nodes with the highest load and the lowest load, we find that the proposed attack strategy is an efficient way to destruct the BA scale-free networks in the range of α. In addition, on the base of the model of BA-BA coupled networks, the preliminary numerical simulation on the proposed attack strategy verifies the mathematic analysis of the targeted-attack to random-attack. By creating a model of the correlated coupled networks for the emergency, we can investigate the condition on cascading failure for the model and propose a protective strategy for preventing avalanche of coupled networks.
2014, 43(6): 923-928.
doi: 10.3969/j.issn.1001-0548.2014.06.022
Abstract:
Latency matrix completion is an important foundation of latency-sensitive applications optimization. On the basis of the in-depth discussion of the robustness of a kind of matrix-factorization based non-gradient descending completion methods, this paper analyzes the significant impact to the intrinsic ill-posed and ill-conditioned inverse problems in the methods caused by the oscillations of the latency sequences. To mitigate the impact and improve the performance of the matrix completion methods in the wild, a regularization factor is introduced to improve the spectrum signature of the coefficient matrix, a median-Kalman filter, a time-spatial federated filtering scheme, is proposed to smooth the latency sequences, and then the topology mutation is obtained through extracting the statistic characters of the latency sequences. The experiments show that our method can avoid the performance degradation caused by noises without losing the major characteristics of the latency sequences, provide robust latency estimation capability, and keep the stress coefficient at a low level about 0.13 during the whole life cycle of the network.
Latency matrix completion is an important foundation of latency-sensitive applications optimization. On the basis of the in-depth discussion of the robustness of a kind of matrix-factorization based non-gradient descending completion methods, this paper analyzes the significant impact to the intrinsic ill-posed and ill-conditioned inverse problems in the methods caused by the oscillations of the latency sequences. To mitigate the impact and improve the performance of the matrix completion methods in the wild, a regularization factor is introduced to improve the spectrum signature of the coefficient matrix, a median-Kalman filter, a time-spatial federated filtering scheme, is proposed to smooth the latency sequences, and then the topology mutation is obtained through extracting the statistic characters of the latency sequences. The experiments show that our method can avoid the performance degradation caused by noises without losing the major characteristics of the latency sequences, provide robust latency estimation capability, and keep the stress coefficient at a low level about 0.13 during the whole life cycle of the network.
2014, 43(6): 929-933.
doi: 10.3969/j.issn.1001-0548.2014.06.023
Abstract:
Data integrity verification in cloud storage mainly uses tree or quasi-tree data structure to store outsourced data, and combines such data structure with appropriate cryptographic techniques to make it authenticated, which is named as authenticated dictionary. This paper designs a new authenticated dictionary based on the size balanced tree and proposes a new data integrity verification scheme based on the new authenticated dictionary. The new scheme supports integrity verification for dynamic data set and avoids periodic reconstruction of authenticated dictionary which can be caused by update operations. Experimental results show that the authenticated dictionary based on SBT has better balance and higher efficiency of data operation than the ones based on AVL tree and Treap.
Data integrity verification in cloud storage mainly uses tree or quasi-tree data structure to store outsourced data, and combines such data structure with appropriate cryptographic techniques to make it authenticated, which is named as authenticated dictionary. This paper designs a new authenticated dictionary based on the size balanced tree and proposes a new data integrity verification scheme based on the new authenticated dictionary. The new scheme supports integrity verification for dynamic data set and avoids periodic reconstruction of authenticated dictionary which can be caused by update operations. Experimental results show that the authenticated dictionary based on SBT has better balance and higher efficiency of data operation than the ones based on AVL tree and Treap.
2014, 43(6): 934-938.
doi: 10.3969/j.issn.1001-0548.2014.06.024
Abstract:
To investigate the effect of paced breathing on cardiovascular system, the cardiovascular variables of heart rate, blood pressure and pulse transit time (PTT) were measured during a stepwise paced breathing procedure (six different breathing rates at[14, 12.5, 11, 9.5, 8, 7]BPM). Respiratory sinus arrhythmia (RSA) was estimated by using autoregressive (AR) model based power spectral analysis. The ensemble empirical mode decomposition (EEMD) was applied to PTT to decompose the signal into different intrinsic mode function, and respiration-derived oscillation and trend component (baseline) in PTT were extracted for further analysis. The results clearly indicate that the stepwise paced breathing procedure can induce increased oscillations in RSA, blood pressure and PTT, meanwhile, reduce blood pressure and lengthen PTT baseline. It was demonstrated that this stepwise paced breathing procedure can lead to blood pressure reduction significantly (p<0.05), and PTT can be used as a maker for the effect of paced breathing on cardiovascular system.
To investigate the effect of paced breathing on cardiovascular system, the cardiovascular variables of heart rate, blood pressure and pulse transit time (PTT) were measured during a stepwise paced breathing procedure (six different breathing rates at[14, 12.5, 11, 9.5, 8, 7]BPM). Respiratory sinus arrhythmia (RSA) was estimated by using autoregressive (AR) model based power spectral analysis. The ensemble empirical mode decomposition (EEMD) was applied to PTT to decompose the signal into different intrinsic mode function, and respiration-derived oscillation and trend component (baseline) in PTT were extracted for further analysis. The results clearly indicate that the stepwise paced breathing procedure can induce increased oscillations in RSA, blood pressure and PTT, meanwhile, reduce blood pressure and lengthen PTT baseline. It was demonstrated that this stepwise paced breathing procedure can lead to blood pressure reduction significantly (p<0.05), and PTT can be used as a maker for the effect of paced breathing on cardiovascular system.
2014, 43(6): 939-942.
doi: 10.3969/j.issn.1001-0548.2014.06.025
Abstract:
Mammalian olfactory system can accurately identify odorants with high specificity and sensitivity. Taking advantage of multiple microelectrode implant technology, we developed a novel in vivo biosensing system for odor detection. The odorant information from conscious rats' olfactory bulb (OB) is extracted by using microelectrode array. High-quality mitral/tufted (M/T) cell activity evoked by odorants could be obtained for at least three weeks. The responses of M/T cell carry sufficient information to discriminate presented odorants. In addition, we found the concentration detection limit of rat is below 10-10 mol/L for carvone. These results demonstrate that in vivo biosensing system has the characteristics of high sensitivity, continuous recording, and specificity, which presents a promising platform for specific trace odorant detection in many fields.
Mammalian olfactory system can accurately identify odorants with high specificity and sensitivity. Taking advantage of multiple microelectrode implant technology, we developed a novel in vivo biosensing system for odor detection. The odorant information from conscious rats' olfactory bulb (OB) is extracted by using microelectrode array. High-quality mitral/tufted (M/T) cell activity evoked by odorants could be obtained for at least three weeks. The responses of M/T cell carry sufficient information to discriminate presented odorants. In addition, we found the concentration detection limit of rat is below 10-10 mol/L for carvone. These results demonstrate that in vivo biosensing system has the characteristics of high sensitivity, continuous recording, and specificity, which presents a promising platform for specific trace odorant detection in many fields.
2014, 43(6): 943-949.
doi: 10.3969/j.issn.1001-0548.2014.06.026
Abstract:
Under runtime and maintenance time constraints during a mission, a simple and efficient modeling method is presented to evaluate mission-availability of k/N(G) fleet. The diagrams describing the fleet operational process and mission-time are given to analyze the relationship of runtime and maintenance time between systems and the fleet. An analytical formula for n/N(G) fleet is deduced by using the formulas of system mission-availability. By combining analytical and simulation methods, a stochastic Petri net model for maintenance process of fleets is given, and the parameters of the model is calculated by combining the analytical formula. The mission-availability of k/N(G) fleet under time constraints is obtained by the simulation model with the parameters. A numerical example is given to illustrate the trends of mission-availability of k/N(G) fleet under operational time-limit or maintenance time-limit, respectively, and the mission-availability difference between time constraints and no time constraints.
Under runtime and maintenance time constraints during a mission, a simple and efficient modeling method is presented to evaluate mission-availability of k/N(G) fleet. The diagrams describing the fleet operational process and mission-time are given to analyze the relationship of runtime and maintenance time between systems and the fleet. An analytical formula for n/N(G) fleet is deduced by using the formulas of system mission-availability. By combining analytical and simulation methods, a stochastic Petri net model for maintenance process of fleets is given, and the parameters of the model is calculated by combining the analytical formula. The mission-availability of k/N(G) fleet under time constraints is obtained by the simulation model with the parameters. A numerical example is given to illustrate the trends of mission-availability of k/N(G) fleet under operational time-limit or maintenance time-limit, respectively, and the mission-availability difference between time constraints and no time constraints.
2014, 43(6): 950-954.
doi: 10.3969/j.issn.1001-0548.2014.06.027
Abstract:
An 1.5 MW wind turbine gearbox is considered as the research object in this paper. The life distribution model of the turbine gearbox is obtained by building dynamic reliability models of mechanical components based on design parameters. The life distributions are assumed to follow Weibull distribution with two parameters and lognormal distribution, and the parameters estimation is conducted with the least square method. The correlation coefficient method is then used to testify the estimation results. The results show that the Weibull distribution fits the life data well.
An 1.5 MW wind turbine gearbox is considered as the research object in this paper. The life distribution model of the turbine gearbox is obtained by building dynamic reliability models of mechanical components based on design parameters. The life distributions are assumed to follow Weibull distribution with two parameters and lognormal distribution, and the parameters estimation is conducted with the least square method. The correlation coefficient method is then used to testify the estimation results. The results show that the Weibull distribution fits the life data well.
2014, 43(6): 955-960.
doi: 10.3969/j.issn.1001-0548.2014.06.028
Abstract:
Initial weights and thresholds of BP neural network are optimized by using Genetic Algorithm(GA) method to solve its slow convergence speed and local optimum. The defect of BP neural network is thus overcome by the proposed method. The direct and inverse dynamic models for a prototype of Magneto-rheological (MR) mount are identified by using traditional BP neural network and novel GA-BP neural network. The results show that the GA-BP neural network has faster convergence rate and higher precision compared with the traditional BP neural network in the identification of direct and inverse model for MR mount.
Initial weights and thresholds of BP neural network are optimized by using Genetic Algorithm(GA) method to solve its slow convergence speed and local optimum. The defect of BP neural network is thus overcome by the proposed method. The direct and inverse dynamic models for a prototype of Magneto-rheological (MR) mount are identified by using traditional BP neural network and novel GA-BP neural network. The results show that the GA-BP neural network has faster convergence rate and higher precision compared with the traditional BP neural network in the identification of direct and inverse model for MR mount.
