检索结果-南通市图书馆

Structural and mechanical stability of rare-earth diborides

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2013年第4期22卷 369-376页

作者： Haci Ozisik Engin Deligoz Kemal Colakoglu Gokhan Surucu department of computer and instructional technologies teaching Aksaray University department of Physics Aksaray University 68100 Aksaray Turkey department of Physics Gazi University Teknikokullar 06500 Ankara Turkey

Structural and mechanical properties of several rare-earth diborides were systematically investigated by first principles calculations. Specifically, we studied XB2 , where X=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Lu in the hexagonal AlB2 , ReB2 , and orthorhombic OsB2 -type structures. The lattice parameters, bulk modulus, bond distances, second order elastic constants, and related polycrystalline elastic moduli （e.g., shear modulus, Young’s modulus, Poisson’s ratio, Debye temperature, sound velocities） were calculated. Our results indicate that these compounds are mechanically stable in the considered structures, and according to ＂Chen’s method＂, the predicted Vickers hardness shows that they are hard materials in AlB2 - and OsB2 -type structures.

关键词： ab initio calculations elastic properties hardness rare-earth diborides

Machine Learning Techniques in Predicting Hot Deformation Behavior of Metallic Materials

在线全文

学校读者我要写书评

暂无评论

computer Modeling in Engineering & Sciences 2025年第1期142卷 713-732页

作者： Petr Opela Josef Walek Jaromír Kopecek department of Metallurgical technologies Faculty of Materials Science and TechnologyVSB–Technical University of OstravaOstrava70800Czech Republic FZU—Institute of Physics of the Czech Academy of Sciences Prague18200Czech Republic

In engineering practice,it is often necessary to determine functional relationships between dependent and independent *** relationships can be highly nonlinear,and classical regression approaches cannot always provide sufficiently reliable ***,Machine Learning(ML)techniques,which offer advanced regression tools to address complicated engineering issues,have been developed and widely *** study investigates the selected ML techniques to evaluate their suitability for application in the hot deformation behavior of metallic *** ML-based regression methods of Artificial Neural Networks(ANNs),Support Vector Machine(SVM),Decision Tree Regression(DTR),and Gaussian Process Regression(GPR)are applied to mathematically describe hot flow stress curve datasets acquired experimentally for a medium-carbon *** the GPR method has not been used for such a regression task before,the results showed that its performance is the most favorable and practically unrivaled;neither the ANN method nor the other studied ML techniques provide such precise results of the solved regression analysis.

关键词： Machine learning Gaussian process regression artificial neural networks support vector machine hot deformation behavior

Tailoring Light–Matter Interactions in Overcoupled Resonator for Biomolecule Recognition and Detection

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano-Micro Letters 2025年第1期17卷 262-280页

作者： Dongxiao Li Hong Zhou Zhihao Ren Cheng Xu Chengkuo Lee department of Electrical and computer Engineering National University of SingaporeSingapore 117583Singapore Center for Intelligent Sensors and MEMS(CISM) National University of SingaporeSingapore 117608Singapore

Plasmonic nanoantennas provide unique opportunities for precise control of light–matter coupling in surface-enhanced infrared absorption(SEIRA)spectroscopy,but most of the resonant systems realized so far suffer from the obstacles of low sensitivity,narrow bandwidth,and asymmetric Fano resonance ***,we demonstrated an overcoupled resonator with a high plasmon-molecule coupling coefficient(μ)(OC-Hμresonator)by precisely controlling the radiation loss channel,the resonator-oscillator coupling channel,and the frequency detuning *** observed a strong dependence of the sensing performance on the coupling state,and demonstrated that OC-Hμresonator has excellent sensing properties of ultra-sensitive(7.25%nm^(−1)),ultra-broadband(3–10μm),and immune asymmetric Fano *** characteristics represent a breakthrough in SEIRA technology and lay the foundation for specific recognition of biomolecules,trace detection,and protein secondary structure analysis using a single array(array size is 100×100μm^(2)).In addition,with the assistance of machine learning,mixture classification,concentration prediction and spectral reconstruction were achieved with the highest accuracy of 100%.Finally,we demonstrated the potential of OC-Hμresonator for SARS-CoV-2 *** findings will promote the wider application of SEIRA technology,while providing new ideas for other enhanced spectroscopy technologies,quantum photonics and studying light–matter interactions.

关键词： Plasmonic nanoantennas Light-matter interaction Surface-enhanced infrared absorption Overcoupled Biosensing

Nonlinear modes in rotating double well potential with parity–time symmetry

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2014年第10期23卷 192-199页

作者：庞玮付神贺吴剑雄黎永耀麦志杰 department of Experiment teaching Guangdong University of Technology State Key Laboratory of Optoelectronic Materials and technologies Sun Yat-Sen University department of Electrical and computer Engineering University of Toronto department of Applied Physics South China Agricultural University

We investigate the nonlinear modes in a rotating double well potential with 79T symmetry. Focus on the existence and stability of the nonlinear PT modes in this system, we found that five types of PT modes can stably exist by given certain parameter settings. The multistable area between these modes are studied numerically and the bistable and tristable areas are delimited. With different input trial wavefunctions, five types of solitary wave modes are identified. We found that the rotating of the potential can significantly affect the power flow of the fundamental harmonic mode, whose effect is absent for the other modes.

关键词： parity-time mode rotating double well potential parity-time symmetric stability diagram

Defensive deception framework against reconnaissance attacks in the cloud with deep reinforcement learning

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2022年第7期65卷 67-85页

作者： Huanruo LI Yunfei GUO Shumin HUO Hongchao HU Penghao SUN department of computer Science Information Engineering University department of Communication technologies Academy of Military Science

Implementing defensive deception in the cloud is promising to proactively counter reconnaissance attack. This technique presents decoys to camouflage cloud assets and distracts attack resource. However,the major challenge is to develop an effective deception strategy to orchestrate digital decoys. To address this issue, we propose a deep reinforcement learning(DRL)-based defensive deception framework. First,we formulate a utility function, which mathematically models underlying threats associated with common vulnerabilities among virtual machines in the cloud. Then, we customize training interfaces and the neural networks for a DRL agent. The reward function reflects the effectiveness of asset concealment and the waste of attack resources, referring to a comprehensive defense goal. Finally, the well-trained DRL agent generates the optimal defense strategy. It specifies a more granular deception strategy than existing proposals. Simulation results show that the proposed framework leads to a 7.87% average advantage in realizing the comprehensive defense goal. Moreover, it can stably improve the concealment degree of cloud assets up to 20.58%, and increase the attack cost up to 40.40%. This study shows that it is promising to improve cloud security with deception defense and artificial intelligence techniques.

关键词： cyber deception defense Cyber Deception Defense artificial intelligence Artificial Intelligence Cloud Security cloud security Reconnaissance Attack reconnaissance attack Deep Reinforcement Learning deep reinforcement learning deception strategy Deception Strategy

同方期刊数据库

Optimization-Based Fragmental Transmission Method for Video Data in Opportunistic Networks

在线全文

学校读者我要写书评

暂无评论

Tsinghua Science and Technology 2017年第4期22卷 389-399页

作者： Peng Li Xiaoming Wang Junling Lu Lichen Zhang Zaobo He the Key Laboratory Modern teaching Technology Ministry of Education School of computer Science Shaanxi Normal University department of computer Science Georgia State University

Multimedia data have become popularly transmitted content in opportunistic networks. A large amount of video data easily leads to a low delivery ratio. Breaking up these big data into small pieces or fragments is a reasonable option. The size of the fragments is critical to transmission efficiency and should be adaptable to the communication capability of a network. We propose a novel communication capacity calculation model of opportunistic network based on the classical random direction mobile model, define the restrain facts model of overhead, and present an optimal fragment size algorithm. We also design and evaluate the methods and algorithms with video data fragments disseminated in a simulated environment. Experiment results verified the effectiveness of the network capability and the optimal fragment methods.

关键词： opportunistic network communication capabilities fragment video data

OpenMDSP:Extending OpenMP to Program Multi-Core DSPs

在线全文

学校读者我要写书评

暂无评论

Journal of computer Science & Technology 2014年第2期29卷 316-331页

作者：何江舟陈文光陈光日郑纬民汤志忠叶寒栋 department of computer Science and Technology Tsinghua University Huawei technologies Co. Ltd.

Multi-core digital signal processors （DSPs） are widely used in wireless telecommunication, core network transcoding, industrial control, and audio/video processing technologies, among others. In comparison with general-purpose multi-processors, multi-core DSPs normally have a more complex memory hierarchy, such as on-chip core-local memory and non-cache-coherent shared memory. As a result, efficient multi-core DSP applications are very difficult to write. The current approach used to program multi-core DSPs is based on proprietary vendor software development kits （SDKs）, which only provide low-level, non-portable primitives. While it is acceptable to write coarse-grained task-level parallel code with these SDKs, writing fine-grained data parallel code with SDKs is a very tedious and error-prone approach. We believe that it is desirable to possess a high-level and portable parallel programming model for multi-core DSPs. In this paper, we propose OpenMDSP, an extension of OpenMP designed for multi-core DSPs. The goal of OpenMDSP is to fill the gap between the OpenMP memory model and the memory hierarchy of multi-core DSPs. We propose three classes of directives in OpenMDSP, including 1） data placement directives that allow programmers to control the placement of global variables conveniently, 2） distributed array directives that divide a whole array into sections and promote the sections into core-local memory to improve performance, and 3） stream access directives that promote big arrays into core-local memory section by section during parallel loop processing while hiding the latency of data movement by the direct memory access （DMA） of a DSP. We implement the compiler and runtime system for OpenMDSP on PreeScale MSC8156. The benchmarking results show that seven of nine benchmarks achieve a speedup of more than a factor of 5 when using six threads.

关键词： OpenMP multi-core digital signal processor data parallelism Long Term Evolution

Microstructural,Mechanical,Electrical,and Thermal Properties of the Bi-Sn-Ag Ternary Eutectic Alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan University of Technology(Materials Science) 2017年第1期32卷 147-154页

作者： KAYA Hasan ENGÍN Sevda AKER Aynur BüYüK Ugur ÇADIRLI Emin Faculty of Education Department of science EducationErciyes UniversityKayseriTurkey Faculty of Thech Department of Energy Systems EngineeringDumluplnar Univ.KütahyaTurkey Faculty of Education Department of Computer and instructional TechnologiesSiirt UniversitySürtTurkey Faculty of Arts and Sciences Department of PhysicsOmer Halisdemir UniversityNigdeTurkey

The development of lead-free solders has emerged as one of the key issues in the electronics packaging ***-Sn-Ag eutectic alloy has been considered as one of the lead-free solder materials that can replace the toxic Pb-Sn eutectic solder without increasing soldering *** investigated the effects of temperature gradient and growth rate on the mechanical,electrical and thermal properties of the BiSn-Ag ternary eutectic ***-47 wt%Sn-0.68 wt%Ag alloy was directionally solidified upward with different temperature gradients（G=2.33-5.66 K/mm） at a constant growth rate（V=13.25 μm/s） and with different growth rates（V=6.55-132.83 μm/s） at a constant temperature gradient（G=2.33 K/mm） in the growth *** microstructures（λ）,microhardness（HV）,tensile stress（σ）,electrical resistivity（ρ）,and thermal properties（△H,Cp,Tm） were measured on directionally solidified *** dependency of the λ,HV,σ,and ρ on G and V was *** to the experimental results,X values decrease with increasing G and V,but HV,λ,and ρ values increase with increasing G and *** of electrical resistivity（ρ） for cast samples with the temperature in the range of 300-400 K were also measured by using a standard dc four-point probe *** enthalpy of fusion（△H） and specific heat（Cp） for the same alloy was also determined by means of differential scanning calorimeter（DSC） from heating trace during the transformation from eutectic liquid to eutectic solid.

关键词： solidification microhardness tensile stress electrical resistivity enthalpy

A trust framework based smart aggregation for machine type communication

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2017年第10期60卷 78-92页

作者： Tabinda SALAM Waheed ur REHMAN Xiaofeng TAO Yu CHEN Ping ZHANG National Engineering Laboratory for Mobile Network technologies Beijing University of Posts and Telecommunication department of computer Science University of Peshawar

Machine type communication(MTC) is one of the significant communication paradigms in the fifth generation networks. The existing cellular networks are not designed for massive access of the MTC ***, data aggregation and relaying are advocated to reduce the massive MTC access besides other physical layer solutions. In this paper, we propose a secured multiple mobile relay selection algorithm that smartly aggregates data from adjacent MTC devices through multiple user equipments and transmits it to the base station(BS). The paper also presents a framework for the selection of trusted relays to cooperatively aggregate MTC data and render two-hop connectivity to the BS. Our proposed algorithm is compared with existing algorithms on the basis of energy efficiency, system capacity, communication delay and outage probability. Our proposed algorithm outperforms the other schemes by improving outage probability and communication delay by 33% and 25%, respectively.

关键词： D2D communication data aggregation machine type communication(MTC) mobile relay MTC offloading