A new technique for the design of broadband circular switched parasitic arrays (SPAs) for portable DVB-T receiver applications in the VHF/UHF bands is presented in this paper. Two switched parasitic arrays are present...
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A new technique for the design of broadband circular switched parasitic arrays (SPAs) for portable DVB-T receiver applications in the VHF/UHF bands is presented in this paper. Two switched parasitic arrays are presented, consisting of an active central element and a uniform ring of five parasitic elements. At any given time slot, only one parasitic element is open- circuited, while the rest remain short-circuited. By properly selecting the open-circuited element, the array is able of selecting among five horizontal radiation patterns. These cover the horizontal plane in a uniform manner, thus achieving effective beam steering in order to maximize and minimize the received power and bit error rate, respectively. Measurement results for both arrays and for a single switching state are presented, and excellent agreement with design considerations and numerical results is demonstrated.
Aiming at the accuracy and error correction of cloud security situation prediction,a cloud security situation prediction method based on grey wolf optimization(GWO)and back propagation(BP)neural network is ***,the ada...
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Aiming at the accuracy and error correction of cloud security situation prediction,a cloud security situation prediction method based on grey wolf optimization(GWO)and back propagation(BP)neural network is ***,the adaptive disturbance convergence factor is used to improve the GWO algorithm,so as to improve the convergence speed and accuracy of the *** Chebyshev chaotic mapping is introduced into the position update formula of GWO algorithm,which is used to select the features of the cloud security situation prediction data and optimize the parameters of the BP neural network prediction model to minimize the prediction output ***,the initial weights and thresholds of BP neural network are modified by the improved GWO algorithm to increase the learning efficiency and accuracy of BP neural ***,the real data sets of Tencent cloud platform are *** simulation results show that the proposed method has lower mean square error(MSE)and mean absolute error(MAE)compared with BP neural network,BP neural network based on genetic algorithm(GA-BP),BP neural network based on particle swarm optimization(PSO-BP)and BP neural network based on GWO algorithm(GWO-BP).The proposed method has better stability,robustness and prediction accuracy.
With the rapid development of mechanical equipment,mechanical health monitoring field has entered the era of big *** learning has made a great achievement in the processing of large data of image and speech due to the...
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With the rapid development of mechanical equipment,mechanical health monitoring field has entered the era of big *** learning has made a great achievement in the processing of large data of image and speech due to the powerful modeling capabilities,this also brings influence to the mechanical fault diagnosis ***,according to the characteristics of motor vibration signals(nonstationary and difficult to deal with)and mechanical‘big data’,combined with deep learning,a motor fault diagnosis method based on stacked de-noising auto-encoder is *** frequency domain signals obtained by the Fourier transform are used as input to the *** method can extract features adaptively and unsupervised,and get rid of the dependence of traditional machine learning methods on human extraction features.A supervised fine tuning of the model is then carried out by *** Asynchronous motor in Drivetrain Dynamics Simulator system was taken as the research object,the effectiveness of the proposed method was verified by a large number of data,and research on visualization of network output,the results shown that the SDAE method is more efficient and more intelligent.
With the popularity of storing large data graph in cloud, the emergence of subgraph pattern matching on a remote cloud has been inspired. Typically, subgraph pattern matching is defined in terms of subgraph isomorphis...
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With the popularity of storing large data graph in cloud, the emergence of subgraph pattern matching on a remote cloud has been inspired. Typically, subgraph pattern matching is defined in terms of subgraph isomorphism, which is an NP-complete problem and sometimes too strict to find useful matches in certain applications. And how to protect the privacy of data graphs in subgraph pattern matching without undermining matching results is an important concern. Thus, we propose a novel framework to achieve the privacy-preserving subgraph pattern matching in cloud. In order to protect the structural privacy in data graphs, we firstly develop a k-automorphism model based method. Additionally, we use a cost-model based label generalization method to protect label privacy in both data graphs and pattern graphs. During the generation of the k-automorphic graph, a large number of noise edges or vertices might be introduced to the original data graph. Thus, we use the outsourced graph, which is only a subset of a k-automorphic graph, to answer the subgraph pattern matching. The efficiency of the pattern matching process can be greatly improved in this way. Extensive experiments on real-world datasets demonstrate the high efficiency of our framework.
This article presents a data management solution based on the data distribution service （DDS） communication model. The basic DDS communication model consists of a unidirectional data exchange where applications that...
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This article presents a data management solution based on the data distribution service （DDS） communication model. The basic DDS communication model consists of a unidirectional data exchange where applications that publish data ＇push＇ the relevant data, which is updated to the local caches of co-located subscribers to the data [1]. DDS has no specified center node to forward data packets and maintain the communication data. This type of publish-subscribe （P/S） model presents integrity and consistency challenges in data management. Unlike peer-to-peer （P2P） distributed storage, DDS applications have a hard real-time environment and fewer data features, and the core problem is ensuring the integrity and consistency of data in distributed systems under this hard real-time environment. This article begins with a brief introduction of the communication model used by DDS, then analyzes persistent data management problems caused by such model, and provides an appropriate solution to these problems. This solution has been implemented in a prototype system of the real-time service bus （RTSB） of Tsinghua University.
Radical extraction is the core technique for radical-based Chinese character recognition. In this paper, we proposed a new method of radical extraction radical cascade classifier. The radical cascade classifier consis...
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An experiment is described for the determination of the overhead associated with N-version programming, a technique for achieving software reliability. Results are presented for the performance as a function of the nu...
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An experiment is described for the determination of the overhead associated with N-version programming, a technique for achieving software reliability. Results are presented for the performance as a function of the number of versions in the voting process. Overhead is defined as additional algorithm execution time as required for the management of the voting process at each algorithm checkpoint. The experiment is conducted in a Unix C environment.
Thanks to the rapid development of naked-eye 3D and wireless communication technology,3D video related applications on mobile devices have attracted a lot of ***,the time-varying characteristics of the wireless channe...
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Thanks to the rapid development of naked-eye 3D and wireless communication technology,3D video related applications on mobile devices have attracted a lot of ***,the time-varying characteristics of the wireless channel is very challenging for conventional source-channel coding based transmission ***,the high complexity of source-channel coding based transmission scheme is undesired for low power mobile *** advanced transmission scheme named Softcast was proposed to achieve efficient transmission performance for 2D image/***,it cannot be directly applied to wireless 3D video transmission with high *** paper proposes a more efficient soft transmission scheme for 3D video with a graceful quality adaptation within a wide range of channel Signal-to-Noise Ratio(SNR).The proposed method first extends the linear transform to 4 dimensions with additional view dimension to eliminate the view redundancy,and then metadata optimization and chunk interleaving are designed to further improve the transmission ***,a synthesis distortion based chunk discard strategy is developed to improve the overall 3D video quality under the condition of limited *** experimental results demonstrate that the proposed method significantly improves the 3D video transmission performance over the wireless channel for low power and low complexity scenarios.
Large language models (LLMs) have demonstrated exceptional performance across a broad spectrum of natural language processing tasks. However, as these models undergo various modifications for deployment, such as quant...
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Dear editor,Data security, including data privacy security and data integrity security, are usually achieved by a cryptographic algorithm. Block ciphers are widely used to design the cryptographic scheme. However, in ...
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Dear editor,Data security, including data privacy security and data integrity security, are usually achieved by a cryptographic algorithm. Block ciphers are widely used to design the cryptographic scheme. However, in some special environments, block ciphers are no longer applicable. A tweakable blockcipher(TBC) is an improved version of a conventional block cipher, which adds an extra input, called tweak,
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