ISSN 
2014 Vol. 43, No. 3
2014, 43(3): 322-328.
doi: 10.3969/j.issn.1001-0548.2014.03.001
Abstract:
In this paper, we apply Principal Component Centrality (PCC), a centrality measure for unweighted networks, to weighted social networks, and propose a weighted centrality measure based on tie strength matrix (TSM). Experiment results show that weighted PCC outperforms weighted EVC (EigenVector Centrality) in spreading effectiveness, robustness and tolerance, hence is feasible and effective in weighted social networks.
In this paper, we apply Principal Component Centrality (PCC), a centrality measure for unweighted networks, to weighted social networks, and propose a weighted centrality measure based on tie strength matrix (TSM). Experiment results show that weighted PCC outperforms weighted EVC (EigenVector Centrality) in spreading effectiveness, robustness and tolerance, hence is feasible and effective in weighted social networks.
2014, 43(3): 329-335.
doi: 10.3969/j.issn.1001-0548.2014.03.002
Abstract:
By adopting local clustering, an automatic iterative clustering algorithm(LAICA) is proposed for complex networks. LAICA first agglomerates groups of nodes tightly connected as local clusters, and then iteratively merge local clusters based on some global modularity criterion. The experiment results demonstrate that LAICA can not only resolve the number of communities automatically, but also assign nodes into their communities accurately. The highest fraction of vertices classified correctly reaches 99.72% on real benchmark networks.
By adopting local clustering, an automatic iterative clustering algorithm(LAICA) is proposed for complex networks. LAICA first agglomerates groups of nodes tightly connected as local clusters, and then iteratively merge local clusters based on some global modularity criterion. The experiment results demonstrate that LAICA can not only resolve the number of communities automatically, but also assign nodes into their communities accurately. The highest fraction of vertices classified correctly reaches 99.72% on real benchmark networks.
2014, 43(3): 336-341.
doi: 10.3969/j.issn.1001-0548.2014.03.003
Abstract:
The dynamic behavior of nodes can significantly influence the topological structure in a network. In order to study this process, four friendship networks with same nodes and different topologies have been constructed. Comparison reveals that 1) the normal-friendship network is a small-world network, 2) the connected structure becomes disconnected along with the increasing of relationship intimacy, and 3) both average degree and clustering coefficient are becoming smaller while the average path length is getting larger. In addition, the degree correlations of the first three networks are negative correlated.
The dynamic behavior of nodes can significantly influence the topological structure in a network. In order to study this process, four friendship networks with same nodes and different topologies have been constructed. Comparison reveals that 1) the normal-friendship network is a small-world network, 2) the connected structure becomes disconnected along with the increasing of relationship intimacy, and 3) both average degree and clustering coefficient are becoming smaller while the average path length is getting larger. In addition, the degree correlations of the first three networks are negative correlated.
2014, 43(3): 342-346.
doi: 10.3969/j.issn.1001-0548.2014.03.004
Abstract:
Peak cancellation is a widely-used technique to reduce peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. However, peak cancellation, when implemented with a window function in time domain, will introduce in-band distortion and out-of-band radiation due to the nonlinear processing. In this paper, the spectral distribution of cancellation noise is analyzed based on a Bussgang nonlinear processing model, which is applied to the noise-aided decoder at the receiver side. The theoretic results are compared with the numeric simulation, and the BER performance is provided.
Peak cancellation is a widely-used technique to reduce peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. However, peak cancellation, when implemented with a window function in time domain, will introduce in-band distortion and out-of-band radiation due to the nonlinear processing. In this paper, the spectral distribution of cancellation noise is analyzed based on a Bussgang nonlinear processing model, which is applied to the noise-aided decoder at the receiver side. The theoretic results are compared with the numeric simulation, and the BER performance is provided.
2014, 43(3): 347-352.
doi: 10.3969/j.issn.1001-0548.2014.03.005
Abstract:
The uniformity of anchor nodes distribution in a wireless sensor network has a very important impact on the positioning accuracy, but the related research is limited. In this paper, a method for measurement of uniformity is presented, a new criterion of normalized uniformity discrepancy is given, and then a hybrid algorithm for node localization is proposed. Experimental results show that the method for measurement of uniformity is effective and the hybrid algorithm improves the positioning accuracy.
The uniformity of anchor nodes distribution in a wireless sensor network has a very important impact on the positioning accuracy, but the related research is limited. In this paper, a method for measurement of uniformity is presented, a new criterion of normalized uniformity discrepancy is given, and then a hybrid algorithm for node localization is proposed. Experimental results show that the method for measurement of uniformity is effective and the hybrid algorithm improves the positioning accuracy.
2014, 43(3): 353-358.
doi: 10.3969/j.issn.1001-0548.2014.03.006
Abstract:
To reduce the delay of QR-decomposition in WLAN (wireless local area network) MIMO-OFDM (multiple input multiple output and orthogonal frequency division multiplexing) systems, a distributed systolic array processor (DSAP) is proposed. The structure uses the coordinate rotation digital computer (CORDIC) in the boundary and internal cells of systolic array, and distributes the QR-decomposition of different sub-carriers into the different stages of the pipelining operation of CORDIC in systolic array. Compared with serial systolic array processor (SSAP), the clock periods can be put to great use in the DSAP, and the delay is reduced by 92% with the same complexity. In SMIC 0.18μm CMOS technology, a 2 ×2 analog-digital mixed MIMO-OFDM chip with DSAP has been implemented, and the test results show that it can reduce the delay of data processing effectively.
To reduce the delay of QR-decomposition in WLAN (wireless local area network) MIMO-OFDM (multiple input multiple output and orthogonal frequency division multiplexing) systems, a distributed systolic array processor (DSAP) is proposed. The structure uses the coordinate rotation digital computer (CORDIC) in the boundary and internal cells of systolic array, and distributes the QR-decomposition of different sub-carriers into the different stages of the pipelining operation of CORDIC in systolic array. Compared with serial systolic array processor (SSAP), the clock periods can be put to great use in the DSAP, and the delay is reduced by 92% with the same complexity. In SMIC 0.18μm CMOS technology, a 2 ×2 analog-digital mixed MIMO-OFDM chip with DSAP has been implemented, and the test results show that it can reduce the delay of data processing effectively.
2014, 43(3): 359-362.
doi: 10.3969/j.issn.1001-0548.2014.03.007
Abstract:
In blind source separation, the second-order and higher-order cumulant matrices of pre-whitened signals have the structure orthogonal joint diagonalization. In eigendecomposition theory, the real symmetry matrices with the same eigenvectors can simultaneous diagonalization. In this paper, a direct orthogonal joint diagonalization algorithm based on eigendecomposition of the cumulant matrices is proposed for blind source separation. In practical computation, we only need part of the cumulant matrices, so the storage and calculation will be greatly reduced. The numerical simulation results show that the performance of our algorithm close to the one of JADE, it is effective for blind source separation.
In blind source separation, the second-order and higher-order cumulant matrices of pre-whitened signals have the structure orthogonal joint diagonalization. In eigendecomposition theory, the real symmetry matrices with the same eigenvectors can simultaneous diagonalization. In this paper, a direct orthogonal joint diagonalization algorithm based on eigendecomposition of the cumulant matrices is proposed for blind source separation. In practical computation, we only need part of the cumulant matrices, so the storage and calculation will be greatly reduced. The numerical simulation results show that the performance of our algorithm close to the one of JADE, it is effective for blind source separation.
2014, 43(3): 363-368.
doi: 10.3969/j.issn.1001-0548.2014.03.008
Abstract:
Transformer is a key device in radio frequency communication circuit, which can directly effect on the performance of the RF front-end circuit. However, there is not transformer in TSMC 0.13m RF CMOS mixed-signal process library. In order to solve this problem, an octagonal transformer which is applied in LTE/WiMAX is designed and fabricated by the analysis of all kinds of on-chip transformer performance, and the frequency-independent lumped-element equivalent circuit model and the parameter-extracted expressions are given. The measurement results show that L and Q have excellent agreement with the measured data from the frequency range of 0.1GHz to 10GHz, and coupling coefficient K is perfect. The successful design of the transformer will contribute to the development and application of 4G communication chips.
Transformer is a key device in radio frequency communication circuit, which can directly effect on the performance of the RF front-end circuit. However, there is not transformer in TSMC 0.13m RF CMOS mixed-signal process library. In order to solve this problem, an octagonal transformer which is applied in LTE/WiMAX is designed and fabricated by the analysis of all kinds of on-chip transformer performance, and the frequency-independent lumped-element equivalent circuit model and the parameter-extracted expressions are given. The measurement results show that L and Q have excellent agreement with the measured data from the frequency range of 0.1GHz to 10GHz, and coupling coefficient K is perfect. The successful design of the transformer will contribute to the development and application of 4G communication chips.
2014, 43(3): 369-374.
doi: 10.3969/j.issn.1001-0548.2014.03.009
Abstract:
Power control is efficiently utilized to improve WiMAX system capacity. For the signal interference and noise ratio (SINR) balance criterion based power control technique, the co-channel interference and the diversity combination of base station antenna have important effect on the SINR. In this paper, co-channel interference (CCI) model for WiMAX networks is presented, the outage probability of SINR with respect to power control is derived based on the CCI model and finally, hard/soft limiting combining algorithms are proposed to reduce interference. Simulation results show that the proposed combining algorithms can suppress the co-channel interference and reduce the outage probability of SINR, so that the power control performance of WiMAX uplink can be improved.
Power control is efficiently utilized to improve WiMAX system capacity. For the signal interference and noise ratio (SINR) balance criterion based power control technique, the co-channel interference and the diversity combination of base station antenna have important effect on the SINR. In this paper, co-channel interference (CCI) model for WiMAX networks is presented, the outage probability of SINR with respect to power control is derived based on the CCI model and finally, hard/soft limiting combining algorithms are proposed to reduce interference. Simulation results show that the proposed combining algorithms can suppress the co-channel interference and reduce the outage probability of SINR, so that the power control performance of WiMAX uplink can be improved.
2014, 43(3): 375-380.
doi: 10.3969/j.issn.1001-0548.2014.03.010
Abstract:
In low earth orbit(LEO) satellite networks, the length of inter-satellite links in high latitude regions are relatively shorter due to the spherical surface of the earth, this results in unbalanced traffic load distribution. In this paper, two load balancing strategies for distributed routing algorithms are proposed based on the horizontal transmitting priority and horizontal transmitting probability. The load balancing strategy based on the horizontal transmitting priority can be used as a real time strategy for its ability of flexibly adjusting the traffic load in a specific district. The horizontal transmitting probability based load balancing strategy is able to adjust the load distribution of the whole network, thus it can be used as a global optimization method. The simulation results prove that both of the strategies are capable of balancing the traffic load in LEO satellite networks.
In low earth orbit(LEO) satellite networks, the length of inter-satellite links in high latitude regions are relatively shorter due to the spherical surface of the earth, this results in unbalanced traffic load distribution. In this paper, two load balancing strategies for distributed routing algorithms are proposed based on the horizontal transmitting priority and horizontal transmitting probability. The load balancing strategy based on the horizontal transmitting priority can be used as a real time strategy for its ability of flexibly adjusting the traffic load in a specific district. The horizontal transmitting probability based load balancing strategy is able to adjust the load distribution of the whole network, thus it can be used as a global optimization method. The simulation results prove that both of the strategies are capable of balancing the traffic load in LEO satellite networks.
2014, 43(3): 381-387.
doi: 10.3969/j.issn.1001-0548.2014.03.011
Abstract:
Edge detection based on Mamdani fuzzy inference regards all features as a whole to carry on one-step inference. However, this will decrease the robustness of algorithm since different features are difficult to guarantee both the sensibility for fuzzy edge and the suppression for noise. This paper presents a step-by-step processing scheme based on multi-features importance-weighted fuzzy inference. According to the importance degree of each feature in the edge representation and noise suppression, the proposed method carries on a step-by-step fuzzy inference and weights all inference results to obtain the edge membership. In addition, this paper presents an improved centroid method based on area approximation, which has higher precision and real-time in defuzzification. The experiment results show the precision, robustness and real-time of the proposed algorithm.
Edge detection based on Mamdani fuzzy inference regards all features as a whole to carry on one-step inference. However, this will decrease the robustness of algorithm since different features are difficult to guarantee both the sensibility for fuzzy edge and the suppression for noise. This paper presents a step-by-step processing scheme based on multi-features importance-weighted fuzzy inference. According to the importance degree of each feature in the edge representation and noise suppression, the proposed method carries on a step-by-step fuzzy inference and weights all inference results to obtain the edge membership. In addition, this paper presents an improved centroid method based on area approximation, which has higher precision and real-time in defuzzification. The experiment results show the precision, robustness and real-time of the proposed algorithm.
2014, 43(3): 388-392.
doi: 10.3969/j.issn.1001-0548.2014.03.012
Abstract:
In order to evaluate in-service performance of high-speed trains, a new method for representing the running state of high-speed trains is proposed based on the multifractal spectrum parameters of the monitoring data is proposed in the paper. The multifractal spectrum of the monitoring data is calculated by using the multifractal theory. The relationship between the multifractal spectrum parameters and the train running states is analyzed, and the multifractal spectrum width Δα, the fractal dimension difference Δf and spectrum skewness k are selected as the characteristics of the high-speed train running states. Experimental results testify that the spectrum parameters can be used to characterize the running state of high-speed trains. When the train running states are changed, the multi-fractal spectrum parameters of the monitoring data are changed accordingly.
In order to evaluate in-service performance of high-speed trains, a new method for representing the running state of high-speed trains is proposed based on the multifractal spectrum parameters of the monitoring data is proposed in the paper. The multifractal spectrum of the monitoring data is calculated by using the multifractal theory. The relationship between the multifractal spectrum parameters and the train running states is analyzed, and the multifractal spectrum width Δα, the fractal dimension difference Δf and spectrum skewness k are selected as the characteristics of the high-speed train running states. Experimental results testify that the spectrum parameters can be used to characterize the running state of high-speed trains. When the train running states are changed, the multi-fractal spectrum parameters of the monitoring data are changed accordingly.
2014, 43(3): 393-399.
doi: 10.3969/j.issn.1001-0548.2014.03.013
Abstract:
Nowadays, more attention has been focused on the estimation of the land surface turbulent fluxes (sensible and latent heat fluxes) with data assimilation method. In this study, a sequential data assimilation scheme is developed based on the concept of the Ensemble Kalman filter (EnKF). It assimilates land surface temperature into a simple land surface model which based on the energy balance theory for the estimation of surface turbulent fluxes. Moreover, from the perspective of error estimation, the simple schemes for estimating model errors and ensemble size are discussed. After construction of the assimilation system, the several numerical experiments tested by Yucheng cropland site in the province of Shandong. Results show that the land surface turbulent fluxes can be retrieved with satisfactory accuracy by using our method(compared to MODIS ET products(MOD16A2), the RMSE of ET results are dropped from 4.18mm to 2.99mm), which indicate the availability of our method in the prediction of surface turbulent fluxes.
Nowadays, more attention has been focused on the estimation of the land surface turbulent fluxes (sensible and latent heat fluxes) with data assimilation method. In this study, a sequential data assimilation scheme is developed based on the concept of the Ensemble Kalman filter (EnKF). It assimilates land surface temperature into a simple land surface model which based on the energy balance theory for the estimation of surface turbulent fluxes. Moreover, from the perspective of error estimation, the simple schemes for estimating model errors and ensemble size are discussed. After construction of the assimilation system, the several numerical experiments tested by Yucheng cropland site in the province of Shandong. Results show that the land surface turbulent fluxes can be retrieved with satisfactory accuracy by using our method(compared to MODIS ET products(MOD16A2), the RMSE of ET results are dropped from 4.18mm to 2.99mm), which indicate the availability of our method in the prediction of surface turbulent fluxes.
2014, 43(3): 400-404.
doi: 10.3969/j.issn.1001-0548.2014.03.014
Abstract:
A parallel method with multi-threading for multi-core embedded browser is introduced in order to improve the speed of browser in multi-core processors. By putting the user interface into the master thread, and loading resources, parsing, layout and painting into the slave thread, this method parallels the serial processes for Web pages. This method can solve the problem of the browser's slow response and low CPU utilization of multicore processors. The feasibility of the method is verified and the speed of rendering the web pages is improved by 18%~40% with memory less than 64 MB memory according to the testing cases.
A parallel method with multi-threading for multi-core embedded browser is introduced in order to improve the speed of browser in multi-core processors. By putting the user interface into the master thread, and loading resources, parsing, layout and painting into the slave thread, this method parallels the serial processes for Web pages. This method can solve the problem of the browser's slow response and low CPU utilization of multicore processors. The feasibility of the method is verified and the speed of rendering the web pages is improved by 18%~40% with memory less than 64 MB memory according to the testing cases.
2014, 43(3): 405-408.
doi: 10.3969/j.issn.1001-0548.2014.03.015
Abstract:
The scale and complexity of software systems continue to increase and the traditional requirement analysis method is difficult to ensure the consistency and correctness of software, which is laying the trouble for the quality of a software system. Practice of the software engineering shows that in the software developing process, the earlier the errors are found and repaired, the less the cost is paid. In order to ensure the quality of software, on the early stage of software development, Event-B can be used to formally describe the software requirements and verify the correctness of the model. In the file system modeling as an example, this paper discusses how to use Event-B method and stepwise refinement to establish and validate the model, so as to ensure the correctness of software.
The scale and complexity of software systems continue to increase and the traditional requirement analysis method is difficult to ensure the consistency and correctness of software, which is laying the trouble for the quality of a software system. Practice of the software engineering shows that in the software developing process, the earlier the errors are found and repaired, the less the cost is paid. In order to ensure the quality of software, on the early stage of software development, Event-B can be used to formally describe the software requirements and verify the correctness of the model. In the file system modeling as an example, this paper discusses how to use Event-B method and stepwise refinement to establish and validate the model, so as to ensure the correctness of software.
2014, 43(3): 409-412.
doi: 10.3969/j.issn.1001-0548.2014.03.016
Abstract:
Cloud storage is drawing tremendous attention in IT field. In it, an open challenge is to keep the privacy of users' outsourced data and securely share users' data. To address this challenge, proxy re-encryption (PRE) scheme is one of promising method. A dynamic type and identity-based PRE scheme will be proposed. This scheme not only obtains the traditional functions of PRE, but also allows a user to update the original types of his outsourced ciphertexts. Compared with the previous PRE scheme, the new feature makes the proposed PRE scheme more useful in practical applications.
Cloud storage is drawing tremendous attention in IT field. In it, an open challenge is to keep the privacy of users' outsourced data and securely share users' data. To address this challenge, proxy re-encryption (PRE) scheme is one of promising method. A dynamic type and identity-based PRE scheme will be proposed. This scheme not only obtains the traditional functions of PRE, but also allows a user to update the original types of his outsourced ciphertexts. Compared with the previous PRE scheme, the new feature makes the proposed PRE scheme more useful in practical applications.
2014, 43(3): 413-419.
doi: 10.3969/j.issn.1001-0548.2014.03.017
Abstract:
In order to reduce the amount of data collected, the compressed sensing (CS), a new sampling method, is used for data acquisition and processing in Internet of Things (IoT). To overcome high computational complexity of CS algorithms, an acceleration scheme based on cloud platform and code migration is introduced in this paper. The scheme solved the automatically translated problem of parallelization code, the migration problem of algorithm, and the synchronization problems of local and cloud. It can use the resources from cloud environment to speed up algorithms by adding several interfaces and inserting some comments. In addition, this paper studies the method of cloud acceleration based on computing resources in Internet of Things, and put forwards an acceleration framework, in combination with multi-CPUs/multi-cores CPU and GPGPU parallelization, to speed up CS algorithm based on the cloud acceleration scheme.
In order to reduce the amount of data collected, the compressed sensing (CS), a new sampling method, is used for data acquisition and processing in Internet of Things (IoT). To overcome high computational complexity of CS algorithms, an acceleration scheme based on cloud platform and code migration is introduced in this paper. The scheme solved the automatically translated problem of parallelization code, the migration problem of algorithm, and the synchronization problems of local and cloud. It can use the resources from cloud environment to speed up algorithms by adding several interfaces and inserting some comments. In addition, this paper studies the method of cloud acceleration based on computing resources in Internet of Things, and put forwards an acceleration framework, in combination with multi-CPUs/multi-cores CPU and GPGPU parallelization, to speed up CS algorithm based on the cloud acceleration scheme.
2014, 43(3): 420-425.
doi: 10.3969/j.issn.1001-0548.2014.03.018
Abstract:
In recent years, feature-opinion pairs classification of Chinese product review is one of the most important research field in Web data mining technology. In this paper, five types of Chinese dependency relationships for product review have been concluded based on the traditional English dependency grammar. The maximum entropy model is used to predict the opinion-relevant product feature relations. To train the model, a set of feature symbol combinations have been designed by means of Chinese dependency. The experiment result shows that the recall and F-score of our approach could reach 78.68% and 75.36% respectively, which is clearly superior to Hu's adjacent based method and Popesecu's pattern based method.
In recent years, feature-opinion pairs classification of Chinese product review is one of the most important research field in Web data mining technology. In this paper, five types of Chinese dependency relationships for product review have been concluded based on the traditional English dependency grammar. The maximum entropy model is used to predict the opinion-relevant product feature relations. To train the model, a set of feature symbol combinations have been designed by means of Chinese dependency. The experiment result shows that the recall and F-score of our approach could reach 78.68% and 75.36% respectively, which is clearly superior to Hu's adjacent based method and Popesecu's pattern based method.
2014, 43(3): 426-431.
doi: 10.3969/j.issn.1001-0548.2014.03.019
Abstract:
JPEG image is one of the commonly used image format. Because of the less redundant data, the length of authentication watermark for JPEG images authentication should be as short as possible. In this paper, combined with matrix encoding and multiple watermarking, a block-level authentication algorithm for JPEG images is proposed. Matrix encoding can shorten the length of the watermark magnitude and accurately locate one information change. And then multi-watermarks are generated for the tampering of the image block authentication. The detailed analysis is given about the missing rate and the false detection rate in this paper. Theoretical analysis and experimental results show that the JPEG images block-level tamper localization can be done under the lower tamper rate. The missing rate and the false detection rate are at the 10-2 level, even if 2 bits watermark are embedded in the rate of tampering is less than 5%.
JPEG image is one of the commonly used image format. Because of the less redundant data, the length of authentication watermark for JPEG images authentication should be as short as possible. In this paper, combined with matrix encoding and multiple watermarking, a block-level authentication algorithm for JPEG images is proposed. Matrix encoding can shorten the length of the watermark magnitude and accurately locate one information change. And then multi-watermarks are generated for the tampering of the image block authentication. The detailed analysis is given about the missing rate and the false detection rate in this paper. Theoretical analysis and experimental results show that the JPEG images block-level tamper localization can be done under the lower tamper rate. The missing rate and the false detection rate are at the 10-2 level, even if 2 bits watermark are embedded in the rate of tampering is less than 5%.
2014, 43(3): 432-436.
doi: 10.3969/j.issn.1001-0548.2014.03.020
Abstract:
The various total variation (TV) algorithms currently reconstruct the lost or deteriorated parts of images by related information of damaged pixel and its 4 neighborhood pixels. Their inpainting accuracy is low because of finite related information. The double cross TV algorithm proposed in this paper divides 8 neighborhood pixels into 2 groups, and computes the pixel value of damaged pixel by using 4 neighborhood pixels in each group respectively. Therefore, the weighted mean of these two pixel values is the final inpainting pixel value. The Experiments show an improvement in PSNR and less iteration number compared with the original TV.
The various total variation (TV) algorithms currently reconstruct the lost or deteriorated parts of images by related information of damaged pixel and its 4 neighborhood pixels. Their inpainting accuracy is low because of finite related information. The double cross TV algorithm proposed in this paper divides 8 neighborhood pixels into 2 groups, and computes the pixel value of damaged pixel by using 4 neighborhood pixels in each group respectively. Therefore, the weighted mean of these two pixel values is the final inpainting pixel value. The Experiments show an improvement in PSNR and less iteration number compared with the original TV.
2014, 43(3): 437-442.
doi: 10.3969/j.issn.1001-0548.2014.03.021
Abstract:
The paper focus on a real-time network, time-triggered Ethernet (TTE), which is used in safety-critical systems. The clock synchronization protocol related to the process of clock synchronization is researched and the permanence algorithm, compression algorithm, and clock synchronization service are analyzed. Then, the simulation platform including the switch model and node model is build. Finally the effectiveness and efficiency of time-triggered Ethernet clock synchronization are simulated and analyzed.
The paper focus on a real-time network, time-triggered Ethernet (TTE), which is used in safety-critical systems. The clock synchronization protocol related to the process of clock synchronization is researched and the permanence algorithm, compression algorithm, and clock synchronization service are analyzed. Then, the simulation platform including the switch model and node model is build. Finally the effectiveness and efficiency of time-triggered Ethernet clock synchronization are simulated and analyzed.
2014, 43(3): 443-449.
doi: 10.3969/j.issn.1001-0548.2014.03.022
Abstract:
Imbalanced demand and supply of data in a layered video coding based P2P Video-on-Demand system lead to severe bandwidth consumption at streaming server. This paper first formulates a mathematical model of bandwidth consumption at streaming server through a viewpoint of bandwidth demand and supply of streaming data. This model can be transferred to a linear programming problem. Then a policy for same/cross layer neighbor selection and bandwidth allocation based on online-time similarity is proposed. Peer can retrieve its requested bandwidth resource from the successors located at the same layer and "helper" located at different layers. Simulation result shows that the proposed policy can efficiently decrease the bandwidth consumption at streaming server under different scenario.
Imbalanced demand and supply of data in a layered video coding based P2P Video-on-Demand system lead to severe bandwidth consumption at streaming server. This paper first formulates a mathematical model of bandwidth consumption at streaming server through a viewpoint of bandwidth demand and supply of streaming data. This model can be transferred to a linear programming problem. Then a policy for same/cross layer neighbor selection and bandwidth allocation based on online-time similarity is proposed. Peer can retrieve its requested bandwidth resource from the successors located at the same layer and "helper" located at different layers. Simulation result shows that the proposed policy can efficiently decrease the bandwidth consumption at streaming server under different scenario.
2014, 43(3): 450-456.
doi: 10.3969/j.issn.1001-0548.2014.03.023
Abstract:
A strategy and implementation for the isolation and protection mechanism of automotive embedded operating system is described. Upon limited hardware resources, the software mechanism satisfies the three-level isolation and protection requirements covering operating system, applications, tasks and interrupt service routines. A protection error handling mechanism is provided with the ability of restricting memory accessing errors to limited regions, reducing the probability of the whole system's failure. The number of memory pages is reduced apparently along with the improvement of operating system performance and utility of memory space. An automotive embedded operating system with isolation and protection mechanism can integrate software components of different sources and safety integration levels into a same ECU system.
A strategy and implementation for the isolation and protection mechanism of automotive embedded operating system is described. Upon limited hardware resources, the software mechanism satisfies the three-level isolation and protection requirements covering operating system, applications, tasks and interrupt service routines. A protection error handling mechanism is provided with the ability of restricting memory accessing errors to limited regions, reducing the probability of the whole system's failure. The number of memory pages is reduced apparently along with the improvement of operating system performance and utility of memory space. An automotive embedded operating system with isolation and protection mechanism can integrate software components of different sources and safety integration levels into a same ECU system.
2014, 43(3): 457-463.
doi: 10.3969/j.issn.1001-0548.2014.03.024
Abstract:
Scientific workflow provides scientific computing with workflow specification, workflow process management, task parallelism, etc. High performance computing provides mechanisms and development interfaces such as cluster management, task management, task scheduling, etc. to scientific computing. While we are entering into a "big data" era, it is necessary to integrate scientific workflow with high performance computing to implement the large scale parallel computing on high performance computing platform. The integration middleware interact with upper workflow systems and underlying HPC platform provides the support for task submission and status monitoring. The integration architecture will be a reference solution to the construction of computing platforms in distributed cluster environment. Taking Swift scientific workflow system and Windows HPC platform integration solution as references, a case study by using a NASA MODIS image processing workflow is presented to analyze and demonstrate the capability of the integrated system.
Scientific workflow provides scientific computing with workflow specification, workflow process management, task parallelism, etc. High performance computing provides mechanisms and development interfaces such as cluster management, task management, task scheduling, etc. to scientific computing. While we are entering into a "big data" era, it is necessary to integrate scientific workflow with high performance computing to implement the large scale parallel computing on high performance computing platform. The integration middleware interact with upper workflow systems and underlying HPC platform provides the support for task submission and status monitoring. The integration architecture will be a reference solution to the construction of computing platforms in distributed cluster environment. Taking Swift scientific workflow system and Windows HPC platform integration solution as references, a case study by using a NASA MODIS image processing workflow is presented to analyze and demonstrate the capability of the integrated system.
2014, 43(3): 464-469.
doi: 10.3969/j.issn.1001-0548.2014.03.025
Abstract:
This paper presents a novel micro-community detection method based on topic model. Multiple latent geographical regions by Dirichlet process are created adaptively. A multinomial distribution is then employed to depict topics evolutions within each time bin. User selection preferences of latent geographical region and community are introduced in topic model. Finally, the EM method and Gibbs sampling method are used to estimate spatio-temporal topic model parameters so that community detection can be realized by topics similarity. Experiment results show that this method can promote the performances of community identifying.
This paper presents a novel micro-community detection method based on topic model. Multiple latent geographical regions by Dirichlet process are created adaptively. A multinomial distribution is then employed to depict topics evolutions within each time bin. User selection preferences of latent geographical region and community are introduced in topic model. Finally, the EM method and Gibbs sampling method are used to estimate spatio-temporal topic model parameters so that community detection can be realized by topics similarity. Experiment results show that this method can promote the performances of community identifying.
2014, 43(3): 470-475.
doi: 10.3969/j.issn.1001-0548.2014.03.026
Abstract:
Heat pipe cold plate is an effective way to cool down electronic equipment. In order to study the heat transfer characteristics and service life of heat pipe cold plate under airborne conditions, nine kinds of different heat pipe cold plates are designed and manufactured, then normal temperature test-bed is developed to investigate the heat transfer characteristics at normal temperature, and high and low temperatures test-bed is built to study the start-up performance and stable-state performance at high and low temperature. The results of normal temperature tests show that the double-U ordinary copper-water heat pipe cold plate has the best heat transform characteristics and the vapor chamber followed. The high and low temperature tests show that both the start-up time and stable temperature of double-U ordinary copper-water heat pipe cold plate are lower than micro-heat pipe arrays, but most affected by temperature, and the same performance of micro-heat pipe arrays with capillary structure are better than that without capillary structure, and least affected by temperature. The research work can provide some foundation for the selection and design of the heat pipe cold plate used for cooling the airborne electronic equipment.
Heat pipe cold plate is an effective way to cool down electronic equipment. In order to study the heat transfer characteristics and service life of heat pipe cold plate under airborne conditions, nine kinds of different heat pipe cold plates are designed and manufactured, then normal temperature test-bed is developed to investigate the heat transfer characteristics at normal temperature, and high and low temperatures test-bed is built to study the start-up performance and stable-state performance at high and low temperature. The results of normal temperature tests show that the double-U ordinary copper-water heat pipe cold plate has the best heat transform characteristics and the vapor chamber followed. The high and low temperature tests show that both the start-up time and stable temperature of double-U ordinary copper-water heat pipe cold plate are lower than micro-heat pipe arrays, but most affected by temperature, and the same performance of micro-heat pipe arrays with capillary structure are better than that without capillary structure, and least affected by temperature. The research work can provide some foundation for the selection and design of the heat pipe cold plate used for cooling the airborne electronic equipment.
2014, 43(3): 476-480.
doi: 10.3969/j.issn.1001-0548.2014.03.027
Abstract:
A new tangential following motion control method of knife blade is proposed for automatic fabric cutting. By this method, following interpolation algorithm of arbitrary 2D curves can be implemented by ordinary motion controllers with a 3-axis linear interpolation function. After curves are discretized into broken lines according to required precision, each cutting piece contour can be divided into a number of segments composing of several lines. And transition between lines in the same segment is realized by rotating knife blade around tool nose. Error analysis and experiments showed that this method, with cutter compensation and adjustable overcutting, is effective and practicable. Compared with existing technology, it provides higher precision and lower cost.
A new tangential following motion control method of knife blade is proposed for automatic fabric cutting. By this method, following interpolation algorithm of arbitrary 2D curves can be implemented by ordinary motion controllers with a 3-axis linear interpolation function. After curves are discretized into broken lines according to required precision, each cutting piece contour can be divided into a number of segments composing of several lines. And transition between lines in the same segment is realized by rotating knife blade around tool nose. Error analysis and experiments showed that this method, with cutter compensation and adjustable overcutting, is effective and practicable. Compared with existing technology, it provides higher precision and lower cost.
