- EI核心期刊
Free-space quantum communication is one of the best ways to realize the global quantum communication network. In the process of free-space quantum communication, the photon polarization states are widely utilized for information encoding and communicating while the polarization states should be preserved. Five kinds of aspects are reviewed which have impact on the photon polarization states in free-space quantum communication. The corresponding physical mechanism and investigation methods are analyzed. Positive effect is shown by study of photon polarization states variation and compensation.
A mixed strategy algorithm based on the mixed-game theory is presented to maximize the node overall throughput in asymmetric multi-channel Ad hoc networks. First, a simple saturation throughput model is presented to quantify to the utility of each node, then, the mixed-game Nash equilibrium model is used to analyze the channel selections. At last, the mixed strategy channel selection algorithm is proposed to maximize the throughput and also improve the fairness of channel selections. Simulation results show that the algorithm can achieve at least 15% improvement compared with random strategy and shared channel selections in multi-user scenarios.
In the pseudonyms based reputation system, there exist conflicts between anonymity and reputation. The reputation evaluation between pseudonyms sometimes appears out of control. A preserving reputation system based conditional anonymity is proposed,with which, the reputation evaluation between pseudonyms is monitored. Only the users who meet the conditional anonymity can obtain the trust value. Violators can be detected and punished. Furthermore, the model makes the real identity blinding reputation account, and based on blind signature, the reputation is updated and the conflict between anonymity and reputation is solved. Analysis shows the scheme guarantees user anonymously gains trust value, updates and demonstrates reputation, makes the reputation in control and limits the ballot-stuffing and Sybil attacks.
A semi-supervised approach based on a three-level framework for product named entity recognition is presented. The structure features and relationships among different parts of product named entities are studied, and a combined method is applied. A hidden conditional random field model is built so as to utilize the hidden status of learned samples. The labels failed to be learned by the bootstrapping algorithm is considered as hidden statuses. Experiment in digital camera area shows that, with only a few manually labeled data, this method could recognize product named entities from text contents of web pages very well.
Due to the computationally-intensive characteristic, the available radio channel simulators of wireless sensor networks (WSN) cannot achieve efficient execution performances. A parallel radio channel simulator using Nvidias graphics processing unit + compute unified device architecture (GPU+CUDA) parallel computing architecture is proposed. Firstly, CUDA-trees is developed, which can reside on the fast on-chip memory of GPU, so as to organize sensor nodes and facilitate detection of possible transmitters in simulation. Secondly, a CUDA parallel radio channel simulating engine is established, which is totally different from that in traditional WSN simulators. Experiments show that this simulating system greatly outperforms a central processing unit implementation with an up to 528.73 times speedup and has a linear scalability.
Derived from end-effecter coordinate system to base coordinate system, a recursive calibration method for robot kinematics parameters is proposed aiming to obtain accuracy robot kinematics parameters. Based on robot kinematics model, an error model of local coordinate systems between adjacent joints is constructed. Taking an 8-degree of freedom robot as research object, the link local coordinate systems are constructed with laser tracker. Then experiments are taken out, and the effectiveness and practicality of the recursive calibration method are verified.
In order to resolve low efficiency of hardware implementation of 2-dimension (2-D) discrete wavelet transform (DWT) based on the method for space time delay and integration charge coupled devices (TDICCD) compression system, a fast implementation structure (128,<em>N</em>) of 2-D lifting-based DWT is proposed. In the direction of line of CCD image, 16 modules of the fast implementation structure of 1-dimension(1-D) line lifting-based DWT are used to decompose image in parallel. Each module uses the value of four delay registers as the intermediate value to compute line wavelet coefficient, which is computed by a fusion structure of two step of prediction and updating. In the direction of line wavelet coefficient, a (32, 16) column lifting-based DWT structure based on multiplexing technology is proposed, which finally completes 2-D lifting-based DWT. The experiment results show that a module of 2-D lifting-based DWT can work fast and stably. The time needed in decomposing a frame image is only 60.198μs. Compared with traditional approaches, the time consuming is decreased by 49.90%, logical resource is decreased by 10.71%, register is decreased by 11.80%, and memory is decreased by 12.98%. Low efficiency of hardware implementation of wavelet module of CCD image compression in space camera is effectively improved.
A modular destruction model is proposed for the infrastructure as a service (IaaS) cloud. It destructs a typical IaaS into 5 sub-systems such as: virtual execution environment sub-system, cloud storage sub-system, virtual network sub-system, modular interconnection sub-system and user management sub-system. Based on this model, the architecture, key functional or design parameters of the main stream IaaS systems, is compared and analyzed. Analysis indicates the future research directions and gives choice of the suitable system for corresponding applications.
The location-based delay tolerant networks (DTN) routing protocol is described, and a new three-dimensional power-aware location-based routing protocol (3DPLRP) is presented. 3DPLRP uses 3D location information of the nodes to decide the route will reduce the overhead of DTNs and introduces a power-aware scheme to extend the network lifetime. Compared with epidemic protocol and priority routing epidemic protocol (PREP) when considering their performance with different network environments, simulation is made and shown that the new one outperforms other two protocols in packet delivery ratio and end-to-end delay with slower moving speed of nodes.
Maximizing the users expected signal may cause interferences to other users in current interference alignment algorithms for multiple-input multiple-output (MIMO) interference channels. It reduces the total channel capacities. Considering the fact that multiple interfering links consist of a game group, a new interference alignment algorithm is presented based on the exact potential game theory. The algorithm designs a mathematic model for interference alignment algorithm based on game theory, and proves that the proposed game is a bounded exact potential game by constructing a bounded potential function which converges to a <em>ε</em>-Nash equilibrium through finite interactions, and also the impact of cost factor on the performance of algorithms is discussed. Simulation shows that the new algorithm is with better performance than the existing minimum-interference (min-INL) and maximum-signal interference noise ratio (max-SINR) interference alignment algorithms and can significantly improve the multi-user networks capacity.
As the smallest resources, the reconfigurable routing platform constructs routing and switching system by supporting, assembling and releasing different services. Based on software components in reconfigurable routing platforms, a method being able to calculate and assess the reliability of the system depended on Petri net is designed and implemented. This method could solve reliability access question towards the asynchronous interactive software components under reconfigurable routing system.
In optical network, heterogeneous destination nodes make throughput of multicast traffic decrease and resource utilization decline. A method for determining optimal layered multicast rate is proposed to maximize the network throughput. Based on the heuristic algorithm, the optimal layer multicast rate is optimized to maximize the network total throughput. Meanwhile, the link share degree is calculated for the multicast tree link. In order to minimize the wavelength bandwidth consumption, the network coding technology is put forward to transmit the packet for the high share degree link. The layered multicast rate and wavelength bandwidth allocation are jointly optimized to resolve the throughput maximal problem for heterogeneous multi-rate network. Furthermore, the proposed method can improve the wavelength bandwidth utilization
Adaptive trimmed mean constant false alarm rate (ATM-CFAR) detection based on TM-CFAR detection and statistics ordered data variability (ODV) is presented. These parameters and background estimations can be selected automatically. Simulation shows that the algorithm has good detection performance under homogeneous environment and multi-target environment, and also increases its tolerance of interfering targets. Moreover, under high clutter noise ratio at clutter edge regions, the control ability on false alarm rate is much better than that of cell average CFAR detection and ordered statistics CFAR detection. Using two-level architecture and sub-block parallel processing methods, its hardware implementation and computational complexity are less than the automatic censored cell-averaging based on the statistics ODV by on-chip implementation. Furthermore, it also has the advantages of high real-time processing and is very convenient for sequential control in practice.
In order to schedule effectively the asynchronous burst in polymorphous optical burst switching (POBS) and reduce burst loss rate, an asynchronous burst delayed insert scheduling algorithm is proposed. Based on the transmission state of periodic traffic in the source ingress node of POBS network and the overlapping degree of the new assembled asynchronous burst, the proposed algorithm delays the burst to the gap of periodic traffic that has the same destination edge node of the burst. The simulation results show that the proposed algorithm can reduce the asynchronous burst loss rate of POBS.
A distributed semantic resources search mechanism for high-dimensional resources is presented. Faced with the problem that the similarity search with high-dimensional resources couldnt be effectively achieved in traditional peer-to-peer (P2P) network, a high-dimensional resource vector model is mapped to the low dimensional space based on dimensionality reduction algorithm based on principal component analysis and then projected to distributed hash table in P2P network which is a simple and effective way to achieve distributed similarity search. Meanwhile, the curse of dimensionality owing to the high dimension of resources could be prevented in the search. The maintenance of the similarity information after processing of dimensionality reduction is analyzed. Simulation based on content addressable network is shown the effectiveness of low-dimensional index built by dimensionality reduction algorithm. The mechanism will achieve a high precision ratio in distributed similarity search for the clustered high-dimensional resources.
The influence of limited feedback on the system throughput is analyzed and the upper bound of throughput loss is derived for the multi-base-station coordination system. The scheme of limited feedback is proposed for the system in two different conditions. The upper bound of system throughput loss is constant by increasing the feedback bits for an increasing signal-to-noise ratio when the number of feedback bits of each cell is equal. The upper bound of system throughput loss is minimized by the proposed optimal feedback allocation mechanism when the total number of feedback bits is fixed.
With maturity of "the Internet of things" and establishment of cloud computing national standards, kinds of terminals appear quickly, and huge amounts of datas generation exponentially increase, so its crucial to construct index for the data. A fast Trie-tree index construction algorithm is proposed. All the strings are sorted and then the sorted strings are preprocessed, and after that a matrix with the element of triple is generated, consisting of the character, the horizontal and vertical offset of the character. The fast algorithm scans each column in turn and skips the repeated rows and columns with the same prefix according to offset value in triple array. The experimental results show that the fast algorithm significantly reduces the construction time compared with traditional algorithm and the performance is better than Aoes double-array Trie construction algorithm.
For the problem of energy detections inability of weak signals and the likelihood ratio test (LRT)s high computational complexity in cognitive radio, the LRT algorithm is simplified under low signal-to-noise ratio (SNR) and its performance parameters are calculated. A spectrum joint detection algorithm is presented based on the simplified LRT, in which the energy detector and the simplified LRT under low SNR are used. Simulation shows that the algorithm detects the primary user signal effectively under low SNR condition, and performs close performance with lower complexity than that of the well-known LRT.
According to access characteristics in the field of education, a hot degree is introduced to characterize the extent of locality based on the educational cloud storage system architecture, and the related calculations based on the spatial and temporal characteristics are implemented. The replica management strategies are designed by applying the concept of service set and Hadoop distributed file system (HDFS). Experiment is conducted on the cloud storage system oriented to education resource: ERS-cloud. It is indicated that the replica management mechanism can effectively improve the efficiency of cloud storage system.
As the basis of the semantic heterogeneity, the calculation of semantic similarity between concepts has become a hot topic. A calculation method based on the comprehensive concept of the semantic similarity of WordNet is presented. The method integrates traditional semantic distance-based algorithm, content-based algorithm, introduces the depth, density factor and semantic coincidence degree to conduct a comprehensive analysis. In order to determine the right weights in the synthesis algorithm, a principal component analysis is proposed to improve the weight allocation. Experiments show that the similarity of the proposed method has good correlation with similarity to the artificial one, thus the accuracy of the concept of semantic similarity calculation is improved effectively.
The distance-aware adaptive relay selection and quality of service (QoS) support algorithm are proposed based on performance of wireless communication. The adaptive cooperative error control mechanism based on cross-layer of hybrid automatic repeat request and automatic repeat request (HARQ-ARQ) is provided. A Markov chain model is built for analyzing the performance of wireless communication according to three different states of the data packets. In the mechanism, ARQ is used at the physical layer and hybrid ARQ is used at the data link layer. Cooperative transmission over multiple relays is proposed based on adaptive relay selection according to the performance between the sending sensor and receiving sensor. Analyses and simulation show that, compared to the traditional ARQ, traditional HARQ, cooperative ARQ and hybrid ARQ respectively, the proposed mechanism could have a better performance in terms of saturation throughput rate, reliability and energy efficiency.
A method of finite-state machine (FSM) based fault detection is proposed to detect faults of event-driven programs. To describe expectation of program behaviors, users specify FSM specifications and insert relevant FSM annotations into the programs. At runtime, software faults are detected through comparing the FSM specifications with collected execution information of the relevant FSMs. Storage and runtime overheads of three detection mechanisms are investigated on two typical node hardware platforms. Two cases are given to demonstrate the effectiveness of the proposed method for sensor node software fault detection.
Through security analysis the receiver can realize existential forgery of the signers signature under known-plaintext attack. And a new efficient arbitrated quantum signature (AQS) scheme is introduced in which the signer sends the each Einstein-Padolsky-Rosen (EPR) pairs to the signer and the receiver. The signer measures the entanglement photons, and the receiver recovers the encrypted quantum message with the received particle and the measurement. By comparing the recovery quantum message with original message, it can ensure the integrity of the signature. In signing phrase, the signer uses new encrypted method to sign the quantum message with the variable, that guarantees the receiver and the signer cannot disavow the signature. The new scheme combines a special quantum gate operation with quantum one-time pads, and it guarantees the receiver cannot use known-plaintext attack and forge the signature.