Along with the proliferating research interest in semantic communication(Sem Com),joint source channel coding(JSCC)has dominated the attention due to the widely assumed existence in efficiently delivering information ...Along with the proliferating research interest in semantic communication(Sem Com),joint source channel coding(JSCC)has dominated the attention due to the widely assumed existence in efficiently delivering information semantics.Nevertheless,this paper challenges the conventional JSCC paradigm and advocates for adopting separate source channel coding(SSCC)to enjoy a more underlying degree of freedom for optimization.We demonstrate that SSCC,after leveraging the strengths of the Large Language Model(LLM)for source coding and Error Correction Code Transformer(ECCT)complemented for channel coding,offers superior performance over JSCC.Our proposed framework also effectively highlights the compatibility challenges between Sem Com approaches and digital communication systems,particularly concerning the resource costs associated with the transmission of high-precision floating point numbers.Through comprehensive evaluations,we establish that assisted by LLM-based compression and ECCT-enhanced error correction,SSCC remains a viable and effective solution for modern communication systems.In other words,separate source channel coding is still what we need.展开更多
To compress hyperspectral images, a low complexity discrete cosine transform （DCT）-based distributed source coding （DSC） scheme with Gray code is proposed. Unlike most of the existing DSC schemes, which utilize tr...To compress hyperspectral images, a low complexity discrete cosine transform （DCT）-based distributed source coding （DSC） scheme with Gray code is proposed. Unlike most of the existing DSC schemes, which utilize transform in spatial domain, the proposed algorithm applies transform in spectral domain. Set-partitioning-based approach is applied to reorganize DCT coefficients into waveletlike tree structure and extract the sign, refinement, and significance bitplanes. The extracted refinement bits are Gray encoded. Because of the dependency along the line dimension of hyperspectral images, low density paritycheck-（LDPC）-based Slepian-Wolf coder is adopted to implement the DSC strategy. Experimental results on airborne visible/infrared imaging spectrometer （AVIRIS） dataset show that the proposed paradigm achieves up to 6 dB improvement over DSC-based coders which apply transform in spatial domain, with significantly reduced computational complexity and memory storage.展开更多
A novel Joint Source and Channel Decoding (JSCD) scheme for Variable Length Codes (VLCs) concatenated with turbo codes utilizing a new super-trellis decoding algorithm is presented in this letter. The basic idea of ou...A novel Joint Source and Channel Decoding (JSCD) scheme for Variable Length Codes (VLCs) concatenated with turbo codes utilizing a new super-trellis decoding algorithm is presented in this letter. The basic idea of our decoding algorithm is that source a priori information with the form of bit transition probabilities corresponding to the VLC tree can be derived directly from sub-state transitions in new composite-state represented super-trellis. A Maximum Likelihood (ML) decoding algorithm for VLC sequence estimations based on the proposed super-trellis is also described. Simu-lation results show that the new iterative decoding scheme can obtain obvious encoding gain especially for Reversible Variable Length Codes (RVLCs),when compared with the classical separated turbo decoding and the previous joint decoding not considering source statistical characteristics.展开更多
This article presents a proposal for a model of a microprogram control unit (CMCU) with output identification adapted for implementation in complex programmable logic devices (CPLD) equipped with integrated memory mod...This article presents a proposal for a model of a microprogram control unit (CMCU) with output identification adapted for implementation in complex programmable logic devices (CPLD) equipped with integrated memory modules [1]. An approach which applies two sources of code and one-hot encoding has been used in a base CMCU model with output identification [2] [3]. The article depicts a complete example of processing for the proposed CMCU model. Furthermore, it also discusses the advantages and disadvantages of the approach in question and presents the results of the experiments conducted on a real CPLD system.展开更多
Most of multimedia schemes employ variable-length codes （VLCs） like Huffman code as core components in obtaining high compression rates. However VLC methods are very sensitive to channel noise. The goal of this pape...Most of multimedia schemes employ variable-length codes （VLCs） like Huffman code as core components in obtaining high compression rates. However VLC methods are very sensitive to channel noise. The goal of this paper is to salvage as many data from the damaged packets as possible for higher audiovisual quality. This paper proposes an integrated joint source-channel decoder （I-JSCD） at a symbol-level using three-dimensional （3-D） trellis representation for first-order Markov sources encoded with VLC source code and convolutional channel code. This method combines source code and channel code state-spaces and bit-lengths to construct a two-dimensional （2-D） state-space, and then develops a 3-D trellis and a maximum a-posterior （MAP） algorithm to estimate the source sequence symbol by symbol. Experiment results demonstrate that our method results in significant improvement in decoding performance, it can salvage at least half of （50%） data in any channel error rate, and can provide additional error resilience to VLC stream like image, audio, video stream over high error rate links.展开更多
When dealing with the large-scale program,many automatic vulnerability mining techniques encounter such problems as path explosion,state explosion,and low efficiency.Decomposition of large-scale programs based on safe...When dealing with the large-scale program,many automatic vulnerability mining techniques encounter such problems as path explosion,state explosion,and low efficiency.Decomposition of large-scale programs based on safety-sensitive functions helps solve the above problems.And manual identification of security-sensitive functions is a tedious task,especially for the large-scale program.This study proposes a method to mine security-sensitive functions the arguments of which need to be checked before they are called.Two argument-checking identification algorithms are proposed based on the analysis of two implementations of argument checking.Based on these algorithms,security-sensitive functions are detected based on the ratio of invocation instances the arguments of which have been protected to the total number of instances.The results of experiments on three well-known open-source projects show that the proposed method can outperform competing methods in the literature.展开更多
In order to provide ultra low-latency and high energy-efficient communication for intelligences,the sixth generation(6G)wireless communication networks need to break out of the dilemma of the depleting gain of the sep...In order to provide ultra low-latency and high energy-efficient communication for intelligences,the sixth generation(6G)wireless communication networks need to break out of the dilemma of the depleting gain of the separated optimization paradigm.In this context,this paper provides a comprehensive tutorial that overview how joint source-channel coding(JSCC)can be employed for improving overall system performance.For the purpose,we first introduce the communication requirements and performance metrics for 6G.Then,we provide an overview of the source-channel separation theorem and why it may not hold in practical applications.In addition,we focus on two new JSCC schemes called the double low-density parity-check(LDPC)codes and the double polar codes,respectively,giving their detailed coding and decoding processes and corresponding performance simulations.In a nutshell,this paper constitutes a tutorial on the JSCC scheme tailored to the needs of future 6G communications.展开更多
An approximately optimal adaptive arithmetic coding (AC) system using a forbidden symbol (FS) over noisy channels was proposed which allows one to jointly and adaptively design the source decoding and channel correcti...An approximately optimal adaptive arithmetic coding (AC) system using a forbidden symbol (FS) over noisy channels was proposed which allows one to jointly and adaptively design the source decoding and channel correcting in a single process, with superior performance compared with traditional separated techniques. The concept of adaptiveness is applied not only to the source model but also to the amount of coding redundancy. In addition, an improved branch metric computing algorithm and a faster sequential searching algorithm compared with the system proposed by Grangetto were proposed. The proposed system is tested in the case of image transmission over the AWGN channel, and compared with traditional separated system in terms of packet error rate and complexity. Both hard and soft decoding were taken into account.展开更多
An iterative detection/decoding algorithm of correlated sources for the LDPC-based relay systems is presented. The signal from the source-destination(S-D) link is formulated as a highly correlated counterpart from the...An iterative detection/decoding algorithm of correlated sources for the LDPC-based relay systems is presented. The signal from the source-destination(S-D) link is formulated as a highly correlated counterpart from the relay-destination(R-D) link. A special XOR vector is defined using the correlated hard decision information blocks from two decoders and the extrinsic information exchanged between the two decoders is derived by the log-likelihood ratio(LLR) associated with the XOR vector. Such the decoding scheme is different from the traditional turbo-like detection/decoding algorithm, where the extrinsic information is computed by the side information and the soft decoder outputs. Simulations show that the presented algorithm has a slightly better performance than the traditional turbo-like algorithm(Taking the(255,175) EG-LDPC code as an example, it achieves about 0.1 dB performance gains aroundBLER=10^(-4)). Furthermore, the presented algorithm requires fewer computing operations per iteration and has faster convergence rate. For example, the average iteration of the presented algorithm is 33 at SNR=1.8 dB, which is about twice faster than that of the turbo-like algorithm, when decoding the(961,721) QC-LDPC code. Therefore, the presented decoding algorithm of correlated sources provides an alternative decoding solution for the LDPC-based relay systems.展开更多
It is known by entropy theory that image is a source correlated with a certain characteristic of probability. The entropy rate of the source and ε- entropy (rate-distortion function theory) are the information conten...It is known by entropy theory that image is a source correlated with a certain characteristic of probability. The entropy rate of the source and ε- entropy (rate-distortion function theory) are the information content to identify the characteristics of video images, and hence are essentially related with video image compression. They are fundamental theories of great significance to image compression, though impossible to be directly turned into a compression method. Based on the entropy theory and the image compression theory, by the application of the rate-distortion feature mathematical model and Lagrange multipliers to some theoretical problems in the H.264 standard, this paper presents a new the algorithm model of coding rate-distortion. This model is introduced into complete test on the capability of the test model of JM61e (JUT Test Model). The result shows that the speed of coding increases without significant reduction of the rate-distortion performance of the coder.展开更多
Software projects are becoming larger and more complicated. Managing those projects is based on several software development methodologies. One of those methodologies is software version control, which is used in the ...Software projects are becoming larger and more complicated. Managing those projects is based on several software development methodologies. One of those methodologies is software version control, which is used in the majority of worldwide software projects. Although existing version control systems provide sufficient functionality in many situations, they are lacking in terms of semantics and structure for source code. It is commonly believed that improving software version control can contribute substantially to the development of software. We present a solution that considers a structural model for matching source code that can be used in version control.展开更多
Hydrocarbon-producing lacustrine basins are widely developed in the world, and China has a large number of lacustrine basins that have developed since the early Permian. The organic-rich shale-dominated heterogeneous ...Hydrocarbon-producing lacustrine basins are widely developed in the world, and China has a large number of lacustrine basins that have developed since the early Permian. The organic-rich shale-dominated heterogeneous source rock intervals in Chinese lacustrine basins generally contain frequent thin interbeds of stratigraphically associated sandstone, siltstone, marl, dolomite, and limestone. The concept of ‘‘Hybrid Plays＇ ＇ as put forth in this article recognizes this pattern of alternating organicrich shale and organic-lean interbeds and existence of mixed unconventional and conventional plays. Hybrid Plays in lacustrine source rock intervals present a unique closed petroleum system hosting continuous hydrocarbons.The interbedded organic-lean siliciclastic and/or carbonateplays are efficiently charged with hydrocarbons via short migration pathways from the adjacent organic-rich shale that is often also a self-sourced play. We assert ‘‘Hybrid Plays＇ ＇ provide the most realistic exploration model for targeting multiple-stacked and genetically related very tight shale, tight and conventional plays together in the entire source rock interval rather than individual plays only. The Hybrid Play model has been proven and works for a wide variety of lacustrine rift, sag and foreland basins in China.展开更多
A neutral beam injection (NBI) system has been developed and is being tested for an Experimental Advanced Superconducting Tokamak (EAST) device. The NBI system needs to be employed for an auxiliary heating and current...A neutral beam injection (NBI) system has been developed and is being tested for an Experimental Advanced Superconducting Tokamak (EAST) device. The NBI system needs to be employed for an auxiliary heating and current drive of EAST plasmas. The first long pulse ion source (LPIS-1) has been installed in the neutral beam test bed (NBTB) system, and the performance is being tested in the NBTB. The LPIS-1 consists of a magnetic bucket plasma generator with multipole cusp-fields and a set of tetrode accelerators with slit-type apertures (a transparency of 60%). The ion beam trajectories of the accelerator column are estimated for the LPIS-1, including an original structure, with the change of slit aperture distance, plasma grid shape, grid gap distance, and voltage ratio between a plasma grid and a gradient grid using the IGUN code. This kind of calculation for the ion beam trajectory may be useful for the estimation of beam extraction characteristics and the direction of accelerator upgrade or modification, prior to the experiments of ion beam extraction.展开更多
A frequency domain analysis method based on the three-dimensional translating-pulsating （3DTP） source Green function is developed to investigate wave loads and free motions of two ships advancing on parallel course ...A frequency domain analysis method based on the three-dimensional translating-pulsating （3DTP） source Green function is developed to investigate wave loads and free motions of two ships advancing on parallel course in waves. Two experiments are carried out respectively to mea- sure the wave loads and the free motions for a pair of side-by- side arranged ship models advancing with an identical speed in head regular waves. For comparison, each model is also tested alone. Predictions obtained by the present solution are found in favorable agreement with the model tests and are more accurate than the traditional method based on the three dimensional pulsating （3DP） source Green function. Numer- ical resonances and peak shift can be found in the 3DP pre- dictions, which result from the wave energy trapped in the gap between two ships and the extremely inhomogeneous wave load distribution on each hull. However, they can be eliminated by 3DTP, in which the speed affects the free sur- face and most of the wave energy can be escaped from the gap. Both the experiment and the present prediction show that hydrodynamic interaction effects on wave loads and free motions are significant. The present solver may serve as a validated tool to predict wave loads and motions of two ves- sels under replenishment at sea, and may help to evaluate the hydrodynamic interaction effects on the ships safety in replenishment operation.展开更多
To improve the performance of MIMO-OFDM video transmission systems on the limitation of wireless bandwidth and transmitting power,we propose an adaptive joint resource allocation algorithm with unequal error protectio...To improve the performance of MIMO-OFDM video transmission systems on the limitation of wireless bandwidth and transmitting power,we propose an adaptive joint resource allocation algorithm with unequal error protection(UEP) based on joint source-channel coding(JSCC) according to H.264 video compression standard and RCPT channel coding.According to different thresholds of the average SNR of subchannels,the algorithm dynamically allocates the source coding parameters of original video data and the channel coding parameters of RCPT,which realizes UEP for the compressed video data of different importance.Through the bit and power allocation based on MQAM modulation and the subspace allocation based on beamforming technology for different subcarriers,an adaptive joint resource allocation making full use of space-frequency domain resources have been realized.The simulation results indicate that the algorithm improves the adaptability of video transmission systems in different wireless environments and the quality of video retrieval.展开更多
The article presents a modification to the method which applies two sources of data. The modification is depicted on the example of a compositional microprogram control unit (CMCU) model with base structure implemente...The article presents a modification to the method which applies two sources of data. The modification is depicted on the example of a compositional microprogram control unit (CMCU) model with base structure implemented in the complex programmable logic devices (CPLD). First, the conditions needed to apply the method are presented, followed by the results of its implementation in real hardware.展开更多
An efficient chaotic source coding scheme operating on variable-length blocks is proposed. With the source message represented by a trajectory in the state space of a chaotic system, data compression is achieved when ...An efficient chaotic source coding scheme operating on variable-length blocks is proposed. With the source message represented by a trajectory in the state space of a chaotic system, data compression is achieved when the dynamical system is adapted to the probability distribution of the source symbols. For infinite-precision computation, the theoretical compression performance of this chaotic coding approach attains that of optimal entropy coding. In finite-precision implementation, it can be realized by encoding variable-length blocks using a piecewise linear chaotic map within the precision of register length. In the decoding process, the bit shift in the register can track the synchronization of the initial value and the corresponding block. Therefore, all the variable-length blocks are decoded correctly. Simulation results show that the proposed scheme performs well with high efficiency and minor compression loss when compared with traditional entropy coding.展开更多
Multi-source network coding allows intermediate nodes to linearly combine packets from multiple sources, but it is vulnerable to pollution attacks which can cause multiple down- stream data to be polluted. To solve th...Multi-source network coding allows intermediate nodes to linearly combine packets from multiple sources, but it is vulnerable to pollution attacks which can cause multiple down- stream data to be polluted. To solve this problem, we take advan- tage of lattice signature and homomorphic property to build a se- cure multi-source network coding scheme. By means of the lattice basis delegation algorithms, our scheme can generate a public lattice for all source nodes and the homomorphic signatures can be calculated on this lattice. Consequently, the multi-source signature problem can be transformed into single-source signature problem only if all source nodes are considered as a whole. Scheme analy- sis shows the correctness and homomorphic property of the pro- posed scheme.展开更多
In the face threat of the Internet attack, malware classification is one of the promising solutions in the field of intrusion detection and digital forensics. In previous work, researchers performed dynamic analysis o...In the face threat of the Internet attack, malware classification is one of the promising solutions in the field of intrusion detection and digital forensics. In previous work, researchers performed dynamic analysis or static analysis after reverse engineering. But malware developers even use anti-virtual machine(VM) and obfuscation techniques to evade malware classifiers. By means of the deployment of honeypots, malware source code could be collected and analyzed. Source code analysis provides a better classification for understanding the purpose of attackers and forensics. In this paper, a novel classification approach is proposed, based on content similarity and directory structure similarity. Such a classification avoids to re-analyze known malware and allocates resources for new malware. Malware classification also let network administrators know the purpose of attackers. The experimental results demonstrate that the proposed system can classify the malware efficiently with a small misclassification ratio and the performance is better than virustotal.展开更多
Knowledge of actinides(n,f) fission process induced by neutron is of importance in the field of nuclear power and nuclear engineering,especially for reactor applications.In this work,fission characteristics of^(238)U(...Knowledge of actinides(n,f) fission process induced by neutron is of importance in the field of nuclear power and nuclear engineering,especially for reactor applications.In this work,fission characteristics of^(238)U(n,f) reaction induced by D-T neutron source were simulated with Geant4 code from multiple perspectives,including the fission production yields,total nubar,kinetic energy distribution,fission neutron spectrum and cumulative γ-ray spectrum of the fission products.The simulation results agree well with the experimental nuclear reaction data(EXFOR) and evaluated nuclear data(ENDF).Mainly,this work was to examine the rationality of the parametric nuclear fission model in Geant4 and to direct our future experimental measurements for the cumulative fission yields of ^(238)U(n,f) reaction.展开更多
基金supported in part by the National Key Research and Development Program of China under Grant No.2024YFE0200600the Zhejiang Provincial Natural Science Foundation of China under Grant No.LR23F010005the Huawei Cooperation Project under Grant No.TC20240829036。
文摘Along with the proliferating research interest in semantic communication(Sem Com),joint source channel coding(JSCC)has dominated the attention due to the widely assumed existence in efficiently delivering information semantics.Nevertheless,this paper challenges the conventional JSCC paradigm and advocates for adopting separate source channel coding(SSCC)to enjoy a more underlying degree of freedom for optimization.We demonstrate that SSCC,after leveraging the strengths of the Large Language Model(LLM)for source coding and Error Correction Code Transformer(ECCT)complemented for channel coding,offers superior performance over JSCC.Our proposed framework also effectively highlights the compatibility challenges between Sem Com approaches and digital communication systems,particularly concerning the resource costs associated with the transmission of high-precision floating point numbers.Through comprehensive evaluations,we establish that assisted by LLM-based compression and ECCT-enhanced error correction,SSCC remains a viable and effective solution for modern communication systems.In other words,separate source channel coding is still what we need.
基金supported by the National Natural Science Foundationof China (60702012)the Scientific Research Foundation for the Re-turned Overseas Chinese Scholars, State Education Ministry
文摘To compress hyperspectral images, a low complexity discrete cosine transform （DCT）-based distributed source coding （DSC） scheme with Gray code is proposed. Unlike most of the existing DSC schemes, which utilize transform in spatial domain, the proposed algorithm applies transform in spectral domain. Set-partitioning-based approach is applied to reorganize DCT coefficients into waveletlike tree structure and extract the sign, refinement, and significance bitplanes. The extracted refinement bits are Gray encoded. Because of the dependency along the line dimension of hyperspectral images, low density paritycheck-（LDPC）-based Slepian-Wolf coder is adopted to implement the DSC strategy. Experimental results on airborne visible/infrared imaging spectrometer （AVIRIS） dataset show that the proposed paradigm achieves up to 6 dB improvement over DSC-based coders which apply transform in spatial domain, with significantly reduced computational complexity and memory storage.
基金Supported by the National Natural Science Foundation of China (No.90304003, No.60573112, No.60272056)the Foundation Project of China (No.A1320061262).
文摘A novel Joint Source and Channel Decoding (JSCD) scheme for Variable Length Codes (VLCs) concatenated with turbo codes utilizing a new super-trellis decoding algorithm is presented in this letter. The basic idea of our decoding algorithm is that source a priori information with the form of bit transition probabilities corresponding to the VLC tree can be derived directly from sub-state transitions in new composite-state represented super-trellis. A Maximum Likelihood (ML) decoding algorithm for VLC sequence estimations based on the proposed super-trellis is also described. Simu-lation results show that the new iterative decoding scheme can obtain obvious encoding gain especially for Reversible Variable Length Codes (RVLCs),when compared with the classical separated turbo decoding and the previous joint decoding not considering source statistical characteristics.
文摘This article presents a proposal for a model of a microprogram control unit (CMCU) with output identification adapted for implementation in complex programmable logic devices (CPLD) equipped with integrated memory modules [1]. An approach which applies two sources of code and one-hot encoding has been used in a base CMCU model with output identification [2] [3]. The article depicts a complete example of processing for the proposed CMCU model. Furthermore, it also discusses the advantages and disadvantages of the approach in question and presents the results of the experiments conducted on a real CPLD system.
基金Supported by the Foundation of Ministry of Education of China (211CERS10)
文摘Most of multimedia schemes employ variable-length codes （VLCs） like Huffman code as core components in obtaining high compression rates. However VLC methods are very sensitive to channel noise. The goal of this paper is to salvage as many data from the damaged packets as possible for higher audiovisual quality. This paper proposes an integrated joint source-channel decoder （I-JSCD） at a symbol-level using three-dimensional （3-D） trellis representation for first-order Markov sources encoded with VLC source code and convolutional channel code. This method combines source code and channel code state-spaces and bit-lengths to construct a two-dimensional （2-D） state-space, and then develops a 3-D trellis and a maximum a-posterior （MAP） algorithm to estimate the source sequence symbol by symbol. Experiment results demonstrate that our method results in significant improvement in decoding performance, it can salvage at least half of （50%） data in any channel error rate, and can provide additional error resilience to VLC stream like image, audio, video stream over high error rate links.
基金This study was supported in part by the National Natural Science Foundation of China(Nos.61401512,61602508,61772549,U1636219 and U1736214)the National Key R&D Program of China(No.2016YFB0801303 and 2016QY01W0105)+1 种基金the Key Technologies R&D Program of Henan Province(No.162102210032)and the Key Science and Technology Research Project of Henan Province(No.152102210005).
文摘When dealing with the large-scale program,many automatic vulnerability mining techniques encounter such problems as path explosion,state explosion,and low efficiency.Decomposition of large-scale programs based on safety-sensitive functions helps solve the above problems.And manual identification of security-sensitive functions is a tedious task,especially for the large-scale program.This study proposes a method to mine security-sensitive functions the arguments of which need to be checked before they are called.Two argument-checking identification algorithms are proposed based on the analysis of two implementations of argument checking.Based on these algorithms,security-sensitive functions are detected based on the ratio of invocation instances the arguments of which have been protected to the total number of instances.The results of experiments on three well-known open-source projects show that the proposed method can outperform competing methods in the literature.
基金supported by National Natural Science Foundation of China(No.92067202,No.62001049,&No.62071058)Beijing Natural Science Foundation under Grant 4222012Beijing University of Posts and Telecommunications-China Mobile Research Institute Joint Innovation Center。
文摘In order to provide ultra low-latency and high energy-efficient communication for intelligences,the sixth generation(6G)wireless communication networks need to break out of the dilemma of the depleting gain of the separated optimization paradigm.In this context,this paper provides a comprehensive tutorial that overview how joint source-channel coding(JSCC)can be employed for improving overall system performance.For the purpose,we first introduce the communication requirements and performance metrics for 6G.Then,we provide an overview of the source-channel separation theorem and why it may not hold in practical applications.In addition,we focus on two new JSCC schemes called the double low-density parity-check(LDPC)codes and the double polar codes,respectively,giving their detailed coding and decoding processes and corresponding performance simulations.In a nutshell,this paper constitutes a tutorial on the JSCC scheme tailored to the needs of future 6G communications.
文摘An approximately optimal adaptive arithmetic coding (AC) system using a forbidden symbol (FS) over noisy channels was proposed which allows one to jointly and adaptively design the source decoding and channel correcting in a single process, with superior performance compared with traditional separated techniques. The concept of adaptiveness is applied not only to the source model but also to the amount of coding redundancy. In addition, an improved branch metric computing algorithm and a faster sequential searching algorithm compared with the system proposed by Grangetto were proposed. The proposed system is tested in the case of image transmission over the AWGN channel, and compared with traditional separated system in terms of packet error rate and complexity. Both hard and soft decoding were taken into account.
基金supported by NSF of China (No.61362010,61661005)NSF of Guangxi (No.2015GXNSFAA139290,2014GXNSFBA118276,2012GXNSFAA053217)
文摘An iterative detection/decoding algorithm of correlated sources for the LDPC-based relay systems is presented. The signal from the source-destination(S-D) link is formulated as a highly correlated counterpart from the relay-destination(R-D) link. A special XOR vector is defined using the correlated hard decision information blocks from two decoders and the extrinsic information exchanged between the two decoders is derived by the log-likelihood ratio(LLR) associated with the XOR vector. Such the decoding scheme is different from the traditional turbo-like detection/decoding algorithm, where the extrinsic information is computed by the side information and the soft decoder outputs. Simulations show that the presented algorithm has a slightly better performance than the traditional turbo-like algorithm(Taking the(255,175) EG-LDPC code as an example, it achieves about 0.1 dB performance gains aroundBLER=10^(-4)). Furthermore, the presented algorithm requires fewer computing operations per iteration and has faster convergence rate. For example, the average iteration of the presented algorithm is 33 at SNR=1.8 dB, which is about twice faster than that of the turbo-like algorithm, when decoding the(961,721) QC-LDPC code. Therefore, the presented decoding algorithm of correlated sources provides an alternative decoding solution for the LDPC-based relay systems.
文摘It is known by entropy theory that image is a source correlated with a certain characteristic of probability. The entropy rate of the source and ε- entropy (rate-distortion function theory) are the information content to identify the characteristics of video images, and hence are essentially related with video image compression. They are fundamental theories of great significance to image compression, though impossible to be directly turned into a compression method. Based on the entropy theory and the image compression theory, by the application of the rate-distortion feature mathematical model and Lagrange multipliers to some theoretical problems in the H.264 standard, this paper presents a new the algorithm model of coding rate-distortion. This model is introduced into complete test on the capability of the test model of JM61e (JUT Test Model). The result shows that the speed of coding increases without significant reduction of the rate-distortion performance of the coder.
文摘Software projects are becoming larger and more complicated. Managing those projects is based on several software development methodologies. One of those methodologies is software version control, which is used in the majority of worldwide software projects. Although existing version control systems provide sufficient functionality in many situations, they are lacking in terms of semantics and structure for source code. It is commonly believed that improving software version control can contribute substantially to the development of software. We present a solution that considers a structural model for matching source code that can be used in version control.
基金National Natural Science Foundation of China (Grant Numbers 40872077 and 41272122)China National Key Technology Research and Development Program (Grant Number 2001BA605A09-1)+1 种基金Sinopec’s Petroleum Exploration and Production Research Institute (Grant No. G5800-15-ZS-WX038)EGI’s China Shale Gas and Shale Oil Plays Consortia (100980) sponsored by 20 multi-national oil companies
文摘Hydrocarbon-producing lacustrine basins are widely developed in the world, and China has a large number of lacustrine basins that have developed since the early Permian. The organic-rich shale-dominated heterogeneous source rock intervals in Chinese lacustrine basins generally contain frequent thin interbeds of stratigraphically associated sandstone, siltstone, marl, dolomite, and limestone. The concept of ‘‘Hybrid Plays＇ ＇ as put forth in this article recognizes this pattern of alternating organicrich shale and organic-lean interbeds and existence of mixed unconventional and conventional plays. Hybrid Plays in lacustrine source rock intervals present a unique closed petroleum system hosting continuous hydrocarbons.The interbedded organic-lean siliciclastic and/or carbonateplays are efficiently charged with hydrocarbons via short migration pathways from the adjacent organic-rich shale that is often also a self-sourced play. We assert ‘‘Hybrid Plays＇ ＇ provide the most realistic exploration model for targeting multiple-stacked and genetically related very tight shale, tight and conventional plays together in the entire source rock interval rather than individual plays only. The Hybrid Play model has been proven and works for a wide variety of lacustrine rift, sag and foreland basins in China.
文摘A neutral beam injection (NBI) system has been developed and is being tested for an Experimental Advanced Superconducting Tokamak (EAST) device. The NBI system needs to be employed for an auxiliary heating and current drive of EAST plasmas. The first long pulse ion source (LPIS-1) has been installed in the neutral beam test bed (NBTB) system, and the performance is being tested in the NBTB. The LPIS-1 consists of a magnetic bucket plasma generator with multipole cusp-fields and a set of tetrode accelerators with slit-type apertures (a transparency of 60%). The ion beam trajectories of the accelerator column are estimated for the LPIS-1, including an original structure, with the change of slit aperture distance, plasma grid shape, grid gap distance, and voltage ratio between a plasma grid and a gradient grid using the IGUN code. This kind of calculation for the ion beam trajectory may be useful for the estimation of beam extraction characteristics and the direction of accelerator upgrade or modification, prior to the experiments of ion beam extraction.
基金supported by the National Natural Science Foundation of China(50879090)the Key Research Program of Hydrodynamics of China(9140A14030712JB11044)
文摘A frequency domain analysis method based on the three-dimensional translating-pulsating （3DTP） source Green function is developed to investigate wave loads and free motions of two ships advancing on parallel course in waves. Two experiments are carried out respectively to mea- sure the wave loads and the free motions for a pair of side-by- side arranged ship models advancing with an identical speed in head regular waves. For comparison, each model is also tested alone. Predictions obtained by the present solution are found in favorable agreement with the model tests and are more accurate than the traditional method based on the three dimensional pulsating （3DP） source Green function. Numer- ical resonances and peak shift can be found in the 3DP pre- dictions, which result from the wave energy trapped in the gap between two ships and the extremely inhomogeneous wave load distribution on each hull. However, they can be eliminated by 3DTP, in which the speed affects the free sur- face and most of the wave energy can be escaped from the gap. Both the experiment and the present prediction show that hydrodynamic interaction effects on wave loads and free motions are significant. The present solver may serve as a validated tool to predict wave loads and motions of two ves- sels under replenishment at sea, and may help to evaluate the hydrodynamic interaction effects on the ships safety in replenishment operation.
基金Sponsored by the Fundamental Research Funds for the Central Universities (Grant No. HIT. NSRIF. 201149)the National Natural Science Foundation of China (Grant No. 61071104)
文摘To improve the performance of MIMO-OFDM video transmission systems on the limitation of wireless bandwidth and transmitting power,we propose an adaptive joint resource allocation algorithm with unequal error protection(UEP) based on joint source-channel coding(JSCC) according to H.264 video compression standard and RCPT channel coding.According to different thresholds of the average SNR of subchannels,the algorithm dynamically allocates the source coding parameters of original video data and the channel coding parameters of RCPT,which realizes UEP for the compressed video data of different importance.Through the bit and power allocation based on MQAM modulation and the subspace allocation based on beamforming technology for different subcarriers,an adaptive joint resource allocation making full use of space-frequency domain resources have been realized.The simulation results indicate that the algorithm improves the adaptability of video transmission systems in different wireless environments and the quality of video retrieval.
文摘The article presents a modification to the method which applies two sources of data. The modification is depicted on the example of a compositional microprogram control unit (CMCU) model with base structure implemented in the complex programmable logic devices (CPLD). First, the conditions needed to apply the method are presented, followed by the results of its implementation in real hardware.
基金Project supported by the Research Grants Council of the Hong Kong Special Administrative Region,China (Grant No.CityU 123009)
文摘An efficient chaotic source coding scheme operating on variable-length blocks is proposed. With the source message represented by a trajectory in the state space of a chaotic system, data compression is achieved when the dynamical system is adapted to the probability distribution of the source symbols. For infinite-precision computation, the theoretical compression performance of this chaotic coding approach attains that of optimal entropy coding. In finite-precision implementation, it can be realized by encoding variable-length blocks using a piecewise linear chaotic map within the precision of register length. In the decoding process, the bit shift in the register can track the synchronization of the initial value and the corresponding block. Therefore, all the variable-length blocks are decoded correctly. Simulation results show that the proposed scheme performs well with high efficiency and minor compression loss when compared with traditional entropy coding.
基金Supported by the National Natural Science Foundation of China(61571024,61272501)the National Basic Research Program of China(2012CB315905)the Research Promotion Grants-in-Aid for KUT Graduates of Special Scholarship Program and the Fundamental Research Funds for Central Universities(YWF15GJSYS059)
文摘Multi-source network coding allows intermediate nodes to linearly combine packets from multiple sources, but it is vulnerable to pollution attacks which can cause multiple down- stream data to be polluted. To solve this problem, we take advan- tage of lattice signature and homomorphic property to build a se- cure multi-source network coding scheme. By means of the lattice basis delegation algorithms, our scheme can generate a public lattice for all source nodes and the homomorphic signatures can be calculated on this lattice. Consequently, the multi-source signature problem can be transformed into single-source signature problem only if all source nodes are considered as a whole. Scheme analy- sis shows the correctness and homomorphic property of the pro- posed scheme.
基金the Project of the Ministry of Science and Technology,Taiwan,China(Nos.NSC 100-2218-E110-004-MY3 and NSC 100-2218-E-110-011)
文摘In the face threat of the Internet attack, malware classification is one of the promising solutions in the field of intrusion detection and digital forensics. In previous work, researchers performed dynamic analysis or static analysis after reverse engineering. But malware developers even use anti-virtual machine(VM) and obfuscation techniques to evade malware classifiers. By means of the deployment of honeypots, malware source code could be collected and analyzed. Source code analysis provides a better classification for understanding the purpose of attackers and forensics. In this paper, a novel classification approach is proposed, based on content similarity and directory structure similarity. Such a classification avoids to re-analyze known malware and allocates resources for new malware. Malware classification also let network administrators know the purpose of attackers. The experimental results demonstrate that the proposed system can classify the malware efficiently with a small misclassification ratio and the performance is better than virustotal.
基金supported by the National Natural Science Foundation of China(No.21327801)
文摘Knowledge of actinides(n,f) fission process induced by neutron is of importance in the field of nuclear power and nuclear engineering,especially for reactor applications.In this work,fission characteristics of^(238)U(n,f) reaction induced by D-T neutron source were simulated with Geant4 code from multiple perspectives,including the fission production yields,total nubar,kinetic energy distribution,fission neutron spectrum and cumulative γ-ray spectrum of the fission products.The simulation results agree well with the experimental nuclear reaction data(EXFOR) and evaluated nuclear data(ENDF).Mainly,this work was to examine the rationality of the parametric nuclear fission model in Geant4 and to direct our future experimental measurements for the cumulative fission yields of ^(238)U(n,f) reaction.
