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Ranked keyword Search Over Encrypted Cloud Data Through Machine Learning Method

IEEE TRANSACTIONS ON SERVICES COMPUTING 2023年第1期16卷 525-536页

作者： Miao, Yinbin Zheng, Wei Jia, Xiaohua Liu, Ximeng Choo, Kim-Kwang Raymond Deng, Robert H. Xidian Univ Sch Cyber Engn Xian 710071 Peoples R China City Univ Hong Kong Hong Kong 999077 Peoples R China City Univ Hong Kong Dept Comp Sci Hong Kong 999077 Peoples R China Fuzhou Univ Coll Math & Comp Sci Key Lab Informat Secur Network Syst Fuzhou 350108 Peoples R China Univ Texas San Antonio Dept Informat Syst & Cyber Secur San Antonio TX 78249 USA Singapore Management Univ Sch Informat Syst Singapore 178902 Singapore

Ranked keyword search over encrypted data has been extensively studied in cloud computing as it enables data users to find the most relevant results quickly. However, existing ranked multi-keyword search solutions cannot achieve efficient ciphertext search and dynamic updates with forward security simultaneously. To solve the above problems, we first present a basic Machine Learning-based Ranked keyword Search (ML-RKS) scheme in the static setting by using the k-means clustering algorithm and a balanced binary tree. ML-RKS reduces the search complexity without sacrificing the search accuracy, but is still vulnerable to forward security threats when applied in the dynamic setting. Then, we propose an Enhanced ML-RKS (called ML-RKS$<^>{+}$+) scheme by introducing a permutation matrix. ML-RKS$<^>{+}$+ prevents cloud servers from making search queries over newly added files via previous tokens, thereby achieving forward security. The security analysis proves that our schemes protect the privacy of indexes, query tokens and keywords. Empirical experiments using the real-world dataset demonstrate that our schemes are efficient and feasible in practical applications.

关键词： Indexes keyword search Cryptography Security Binary trees Complexity theory Servers Ranked keyword search k-means clustering algorithm balanced binary tree permutation matrix forward security

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Experimental and numerical validation of high strain rate impact response and progressive damage of 3D orthogonal woven composites

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COMPOSITES SCIENCE AND technology 2024年 258卷

作者： Yang, Xue Li, Dian-sen Jia, Xiao-long Zuo, Hong-mei Jiang, Lei Lomov, Stepan V. Desplentere, Frederik Beihang Univ Sch Chem Minist Educ Key Lab Bioinspired Smart Interfacial Sci Technol Beijing 100191 Peoples R China Leuven KU Dept Mat Engn Leuven Belgium Beijing Univ Chem Technol State Key Lab Organ Inorgan Composites Beijing 100029 Peoples R China Anhui Polytech Univ Sch Text & Garment Adv Fiber Mat Engn Res Ctr Anhui Prov Wuhu 241000 Peoples R China

advanced three-dimensional (3D) woven composites for aerospace and automotive applications are commonly subjected to complex dynamic environments involving vibrations and impacts, resulting in examining their impact properties is extremely important. This paper first experimentally discussed the influences of strain rates, weft yarn densities and loading directions on the impact performances and failure mechanisms of 3D orthogonal woven composites (3DOWCs). Secondly, full-scale finite element models were developed to predict the stress distribution and interfacial damage evolution process. The predictions were well in agreement with the experimental results. This research revealed that the impact characteristics exhibited strain rate sensitivity. With increasing weft yarn densities, the high strain rate impact behaviors also improved. Particularly, the warp impact strength of 3DOWCs with a weft yarn density of 2 yarn/cm (W5-2) at 812 s(-1) was 17.4% and 24.0% higher than that of 3DOWCs with a weft yarn density of 1.5 yarn/cm (W5-1) at 822 s(-1). Meanwhile, warp impact strength consistently exceeded to that of the weft impact strength. Additionally, strain rates, weft yarn densities, and loading directions dramatically affected the stress distribution and interfacial damage evolution process of 3DOWCs. Significant warp yarns fracture and matrix cracking were the principal failure patterns in the warp impact, whereas the damage in the weft impact was dominated by localized fracture of weft yarns and interfacial debonding.

关键词： A. Textile composites B. Impact behaviour B. Stress/strain curves C. Damage mechanics C. Finite element analysis (FEA)

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Microstructure and tribological behavior of Al-12Si-Nano graphene composite fabricated by laser metal deposition process

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JOURNAL OF MATERIALS RESEARCH AND technology-JMR&T 2023年 27卷 2311-2322页

作者： Yang, Zhilu Ma, Pan Zhang, Nan Yang, Dongye Gokuldoss, Prashanth Konda Jia, Yandong Shanghai Univ Engn Sci Sch Mat Sci & Engn Shanghai Peoples R China Harbin Inst Technol State Key Lab Adv Welding & Joining Harbin 150001 Peoples R China Tallinn Univ Technol Dept Mech & Ind Engn Ehitajate Tee 5 EE-19086 Tallinn Estonia Vellore Inst Technol Sch Mech Engn CBCMT Vellore 630014 Tamil Nadu India Shanghai Univ Inst Mat Lab Microstruct Shanghai 200444 Peoples R China

To improve the wear resistance of the Al-based alloys and extend its application spectrum, graphene nano-platelets (GNPs) reinforced Al-12Si matrix composites were fabricated by laser melting deposition (LMD) technology. The microstructure, wear morphologies and surface roughness were characterized by scanning electron microscopy (SEM), electron back-scattered diffraction (EBSD) setups and 3D confocal microscopy. The microhardness and high-speed reciprocating frictional properties both Al-12Si and GNPs/Al-12Si composites were evaluated. The addition of graphene significantly refines the microstructure and improves the wear resistance of the matrix. The formation of a relatively stable mechanically mixed layer (MML) reduces the contact area between the friction pair material and the wear surface, the wear rate and roughness of the Al-12Si - 0.5 wt% GNP reinforced composites decrease with the increase of sliding speed, and the wear mechanism changes from adhesive wear accompanied by abrasive wear to fatigue wear. Meanwhile, as the load increases, the wear rate and roughness increase. The wear mechanism of the composite changes from abrasive wear to a mixed mode (combination of both adhesive and abrasive). This research not only offers valuable information about the Al-Si-based composites but provides theoretical light on their industrial applications. (c) 2023 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND

关键词： Nano graphene nano-platelets (GNPs) Al-12Si Laser melting deposition (LMD) Microstructure Wear resistance

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Polynorepinephrine-regulated filler sulfonation toward interfacial reformation and conductive promotion of nanocomposite proton exchange membrane

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CHEMICAL engineering JOURNAL 2024年 484卷

作者： Huang, Tong Liu, Xin Ma, Ruibin Gao, Yangyang Xu, Xiaomin Yan, Chengrun Guo, Yuchen Li, Xiaoxu Qin, Yanzhou Liu, Lingling Xue, Jiandang Huang, Huadong Zhang, Xiyuan Yin, Xiaochun Zhai, Shaoxiong Zhao, Tianbao Chen, Jiechao Jia, Xiaoyang He, Shaojian Lin, Jun Zhang, Liqun Tianjin Univ Sch Mech Engn State Key Lab Engines Tianjin 300072 Peoples R China Sichuan Diwei Energy Technol Co Ltd Mianyang 621000 Peoples R China Nanjing Tech Univ Coll Chem Engn State Key Lab Mat Oriented Chem Engn Nanjing 211816 Peoples R China Chengdu Vehicle Environm Protect Technol Co Ltd Chengdu 610093 Peoples R China Beijing Univ Chem Technol State Key Lab Organ Inorgan Composites Beijing 100029 Peoples R China Zhejiang Univ State Key Lab Clean Energy Utilizat Hangzhou 310007 Peoples R China Sichuan Univ State Key Lab Polymer Mat Engn Chengdu 610065 Peoples R China Univ Tokyo Grad Sch Frontier Sci Chiba 2778561 Japan Hubei Univ Automot Technol Hubei key Lab Energy Storage & Power Battery Shiyan 442002 Peoples R China South China Univ Technol Guangdong Prov Key Lab Tech & Equipment Macromol A Guangzhou 510640 Peoples R China Beijing Inst Smart Energy Beijing 101499 Peoples R China Tsinghua Univ Key Lab Adv Mat Minist Educ Beijing 100084 Peoples R China Xihua Univ Sch Mat Sci & Engn Key Lab Mat & surface Technol Minist Educ Chengdu 610039 Peoples R China Dongguan Univ Technol Guangdong Prov Key Lab Distributed Energy Syst Dongguan 523808 Peoples R China North China Elect Power Univ State Key Lab Alternate Elect Power Syst Renewable Beijing 102206 Peoples R China

Interfacial compatibility between filler and matrix substantially affects the overall morphology and performance of nanocomposites. Compared with bare montmorillonite (MMT), surface modified product such as sulfonated MMT (SMMT) has been known to render optimized interfacial compatibility in composite proton exchange membranes (PEMs) for proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs). Nevertheless, in-depth understanding and investigation on the sulfonation of MMT are seldom focused, such as uniformity and sufficiency. Herein, these broadly neglected issues are proposed and resolved using an exemplary polynorepinephrine (PNE)-regulated SMMT (SNMMT). Rather than direct sulfonation utilizing the inherent hydroxyl groups of MMT, a PNE coating with ample hydroxyl groups is deposited on MMT beforehand, which results in more homogeneous and sufficient sulfonation of SNMMT. Compared with normal SMMT, this alteration on surficial geography of filler functionalization brings significant benefits when composited with Nafion matrix, including harmonized filler-matrix compatibility, improved mechanical stability and enhanced proton conduction. Moreover, the antioxidative ability of PNE layer enables improved chemical stability of nanocomposite PEM. The Nafion/SNMMT composite PEM achieves 0.275 S cm-1 proton conductivity at 95 degrees C in water, evidently beyond any previously reported composite PEMs using normal SMMT. Equipped with this reformed nanocomposite PEM, both PEMFC and DMFC display competitive peak power densities (1.121 W cm-2 with H2/ O2 at 80 degrees C/100 % relative humidity (RH) for PEMFC, and 0.228 W cm-2 with 1.6 M methanol/100 % RH O2 for DMFC), and simultaneously show minor performance deteriorations in constant current density operation and RH cycle tests. It would be instructive the specific focus and reformation on the uniformity and sufficiency of filler modification may render significant interface and performance ad

关键词： Organic -inorganic nanocomposite Filler functionalization Interfacial compatibility Proton conduction Fuel cell

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Thermally stable inorganic Bi0.4Sb1.6Te3/metal-organic framework (MOF) composites with 1-by-1 nm pore engineering towards mid-temperature thermoelectrics

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ENERGY & ENVIRONMENTAL SCIENCE 2024年第15期17卷 5679-5690页

作者： Zhang, Wanjia Al-Maythalony, Bassem A. Gao, Fengxian Wu, Fanshi Zhao, Wei Xu, Pengfei Zhang, Wenhua Chen, Cailing Shi, Zhan Wang, Xiyang Lou, Yue Xu, Biao Nanjing Univ Sci & Technol Sch Chem & Chem Engn Nanjing 210094 Peoples R China Royal Sci Soc Adv Res Ctr Mat Discovery Res Unit Amman 11941 Jordan Univ Sci & Technol Beijing Sch Chem & Biol Engn Beijing 100083 Peoples R China Univ Sci & Technol China Natl Synchrotron Radiat Lab Anhui Prov Engn Lab Adv Funct Polymer Film Hefei 230026 Peoples R China King Abdullah Univ Sci & Technol KAUST Adv Membranes & Porous Mat AMPM Ctr Phys Sci & Engn Div Thuwal 239556900 Saudi Arabia Jilin Univ Coll Chem State Key Lab Inorgan Synth & Preparat Chem Changchun 130012 Peoples R China

Metal-organic frameworks (MOFs) exhibit substantial promise in the field of thermoelectrics, thanks to their adjustable porosity and modifiable physical/chemical characteristics. The widespread application of MOFs in thermoelectricity has been hampered by their low conductivity and limited thermal stability. In this work, a uniform dispersion of MOFs within the Bi0.4Sb1.6Te3 matrix is realized. This results in dual benefits: the assurance of microstructural stability of MOFs within the composites and a significant enhancement in electrical transport of Bi0.4Sb1.6Te3 induced by the organic-inorganic interfacial electron transfer. Meanwhile, the 1-by-1-nm-tuned pores and intricate hierarchical architecture of MOFs play crucial roles in diminishing the thermal conductivity of Bi0.4Sb1.6Te3. Consequently, the notable thermoelectric performance of the Bi0.4Sb1.6Te3/0.5 wt% ZIF-8 nanocomposite is achieved, including a peak zT of 1.65 at 348 K, a remarkable maximum cooling Delta T of 71.6 K at T-h = 300 K, and a record-high thermoelectric conversion efficiency of 6.7% at Delta T = 238 K. This study utilizes the unique structural features of MOFs, broadening their applications into the mid-temperature range within the field of thermoelectrics.

关键词： Thermodynamic stability

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Laser shock peening of laser melting deposited TiAl alloy for enhancing its corrosion resistance

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SURFACE & COATINGS technology 2024年 483卷

作者： Jiang, Lulu Lan, Liang Wang, Haoyu Yan, Xiao Gao, Shuang He, Bo Chen, Chaoyue Shanghai Univ Engn Sci Res Ctr High Temp Alloy Precis Forming Sch Mat Sci & Engn Shanghai 201620 Peoples R China Shanghai Univ Sch Mat Sci & Engn State Key Lab Adv Special Steels Shanghai 200444 Peoples R China

Laser shock peening (LSP), as a post-treatment process, was employed to improve the corrosion resistance of Ti45Al8Nb alloy fabricated via laser melting deposition (LMD). Microstructure analysis indicated that nanograins and nanotwins structures were formed on the surface layer of LSP-treated Ti45Al8Nb alloy, accompanied by high-density dislocations and stacking faults. Electrochemical results showed that LSP improves the corrosion resistance of Ti45Al8Nb alloy. The formation of nanograins, nanotwins and compressive residual stress during LSP was conductive to dense oxidation films, thus improving the corrosion resistance of the as-deposited Ti45Al8Nb alloy.

关键词： Laser shock peening TiAl alloy Laser melting deposition Microstructure Corrosion resistance

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Performance improvement by an optimum companding-based Non-Uniform quantization scheme in low-bit resolution IMDD-UFMC system

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OPTICAL FIBER technology 2024年 88卷

作者： Li, Zhengmin Bi, Meihua Zhao, Lou Xu, Hangyong Teng, Xuyang Hu, Miao Hangzhou Dianzi Univ Sch Commun Engn Xiasha Gaojiaoyuan 2rd St Hangzhou 310018 Zhejiang Peoples R China Shanghai Jiao Tong Univ Dept Elect Engn State Key Lab Adv Opt Commun Syst & Networks 800 Dongchuan Rd Shanghai 200240 Peoples R China Soochow Univ Res Ctr New Opt Fiber Technol & Commun Network Eng 333 Ganjiang East Rd Suzhou 215301 Jiangsu Peoples R China

In this paper, an optimum non-uniform quantization method is presented in the intensity-modulated direct detection universal filter multicarrier (IMDD-UFMC) system to achieve the system performance improvement with low-bit resolution digital-to-analog converter (DAC). By this specifically-designed companding quantizer without the probability density function (PDF) estimation, the number and interval size of the quantization interval allocated in the low probability region and the high probability region can be balanced with a modified optimal mapping relationship to obtain the optimal quantized level and then the low quantization noise is realized to greatly reduce the bit resolution of DAC in IMDD-UFMC system. Owing to this scheme is essentially a peak-to-average power ratio (PAPR) suppression technology of signal distortion, PAPR performance can be improved at the same time. Compared to the clustering and nonlinear programming schemes, the system performance in term of bit error rate (BER) can be improved and the difficulty of implementation can be reduced in the 25-Gb/s transmission system through 20-km fiber transmission. Moreover, a simplified method is presented by fitting the corresponding companding curve with error function and logistic function, which further decreases the complexity of the optimal non-uniform quantization. In this way, our scheme can offer a significant advancement in the design of IMDD-UFMC systems and has the potential to enhance the performance of future multi-carrier optical communication systems.

关键词： Intensity -modulated direct detection (IMDD) Universal filter multicarrier (UFMC) Non -Uniform quantization Low -bit resolution

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A study of boundary conditions for pedestrian thorax impact test

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International Journal of Vehicle Systems Modelling and Testing 2024年第2期18卷 120-133页

作者： Long, Yongcheng Liu, Yu Xiao, Yu Ruan, Zhisheng Xiao, Zhi Zhang, Guanjun Huang, Jing State Key Laboratory of Intelligent Vehicle Safety Technology Chongqing401122 China China Automotive Engineering Research Institute Co. Ltd. Chongqing401122 China Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Hunan University Changsha410082 China

Thorax injury is one of the main injuries during pedestrian impacts, and it is important to determine the boundary conditions for pedestrian thorax impactor tests. A series of virtual cases were built up to simulate the vehicle-pedestrian impact accidents. Then, the kinematic process was analysed during the vehicle-pedestrian impacts, and thorax impact parameters were extracted. Finally, the statistical characteristics of these impact parameters were obtained for thorax impactor tests. The results show that vehicle type affects the pedestrian impact kinematics and thorax impact parameters significantly. The range of thorax wrap-around distance is 928~1915 mm and 1018~1762 mm during sedan-pedestrian impact and SUV-pedestrian impact respectively. The average thorax impact speeds are about 5.8 m/s and 4.8 m/s in sedan-pedestrian impact and in SUV-pedestrian impact respectively. The average thorax impact velocity angles are 26.8° and 19.5° respectively. These results can provide the effective reference data for pedestrian thorax impactor tests. Copyright © 2024 Inderscience Enterprises Ltd.

关键词： Kinematics

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Stripline Kicker Design for On-axis Injection System in WHPS Low-energy Storage Ring 3

Stripline Kicker Design for On-axis Injection System in WHPS...

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3rd IEEE China International Youth Conference on Electrical engineering, CIYCEE 2022

作者： Lei, Jian Yang, Jun Fan, Ziyu Luo, Zhengqiu Yuan, Yi Hu, Chen Li, Xiaofei Fan, Kuanjun School of Electrical and Electronic Engineering Huazhong University of Science and Technology State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan430074 China State Grid Jiangxi Electric Power Supply Company Nanchang330096 China China Electric Power Research Institute Wuhan430074 China

ISBN: (数字)9781665477321

ISBN: (纸本)9781665477321

Wuhan Photon Source (WHPS) utilizes the on-axis swap-out injection scheme in the low-energy storage ring for its small dynamic aperture feature. Traveling-wave stripline kickers for nanosecond injection and extraction have been employed to satisfy the time requirements of the injection system. This paper analyses the injection process and designs a stripline kicker for the WHPS low-energy storage ring. However, Time Domain Reflectometry (TDR) simulation points out that impedance mismatching occurs around the feedthrough-electrode connection, which may deteriorate the deflection field and decrease the injection efficiency. Thus, we optimized the connection to improve the impedance matching. TDR, field homogeneity, and reflection parameter simulation were performed to optimize the performance of the stripline kickers. © 2022 IEEE.

关键词： Light sources

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The aging behavior,microstructure and mechanical properties of AlN/AZ91 composite

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Journal of Magnesium and Alloys 2023年第7期11卷 2458-2468页

作者： Yunxia Sun Changlin Yang Bin Zhang Jianfeng Fan Hongxiang Li Tianhao Zhao Jing Li State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’anShaanxi 710072PR China Yangtze River Delta Research Institute of NPU TaicangJiangsu 215400PR China Key Laboratory of Interface Science and Engineering in Advanced Materials Ministry of EducationTaiyuan University of TechnologyTaiyuan 030024PR China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083PR China

Microstructure evolution and mechanical properties of the aging treated AlN/AZ91 composites were systematically investigated by optical microscopy(OM),high resolution scanning electron microscopy(HRSEM)with an energy dispersive spectrum(EDS),and high-angle annular dark field scanning transmission electron microscopy(HAADF-STEM).The results show that the higher fracture elongation(14±1%)and ultimate tensile strength(275±6 MPa)were simultaneously obtained in the peak-aged AlN/AZ91 *** with AZ91 matrix alloy,the strength was increased by about 44%and the elongation was approximately five times higher,which mainly attributed to the precipitation of nano-sizedγ-Mg_(17)Al_(12)phase and the activation of non-basal slip systems induced by in-situ AlN particles at room ***,the in-situ formation of AlN reinforcements consumed part of Al element in the matrix alloy,which resulted into the volume fraction decreasing ofγ-Mg_(17)Al_(12)precipitates,and then the age hardening and strengthening efficiency were reduced in the AlN/AZ91 *** the other hand,the mismatch of thermal expansion coefficient between AlN particles and AZ91 matrix generated high density dislocations around AlN particles,which promoted the precipitation ofγ-Mg_(17)Al_(12)phase,and then the peak aging time and temperature were decreased.

关键词： Magnesium matrix composites In-situ AlN particles Aging behavior Microstructure Mechanical properties

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