检索结果-南通市图书馆

Computers, Materials & Continua 2019年第6期59卷 817-832页

作者： Wentao Zhao pan li Chengzhang Zhu Dan liu Xiao liu College of Computer National University of Defense TechnologyChangsha410073China Faculty of Engineering and Information Technology University of Technology Sydney2007Australia

The defense techniques for machine learning are critical yet challenging due tothe number and type of attacks for widely applied machine learning algorithms aresignificantly increasing. Among these attacks, the poisoning attack, which disturbsmachine learning algorithms by injecting poisoning samples, is an attack with the greatestthreat. In this paper, we focus on analyzing the characteristics of positioning samples andpropose a novel sample evaluation method to defend against the poisoning attack cateringfor the characteristics of poisoning samples. To capture the intrinsic data characteristicsfrom heterogeneous aspects, we first evaluate training data by multiple criteria, each ofwhich is reformulated from a spectral clustering. Then, we integrate the multipleevaluation scores generated by the multiple criteria through the proposed multiplespectral clustering aggregation (MSCA) method. Finally, we use the unified score as theindicator of poisoning attack samples. Experimental results on intrusion detection datasets show that MSCA significantly outperforms the K-means outlier detection in terms ofdata legality evaluation and poisoning attack detection.

关键词： Poisoning attack sample evaluation spectral clustering ensemble learning.

Size-controlled MoS2 nanodots supported on reduced graphene oxide for hydrogen evolution reaction and sodium-ion batteries

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 Research 2017年第7期10卷 2210-2222页

作者： Weiyi Sun pan li Xue liu Jiajia Shi Hongming Sun Zhanliang Tao Fujun li Jun Chen Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) Collaborative Innovation Center of Chemical Scienceand Engineering College of Chemistry Nankai University Tianjin 300071 China

Transition metal dichalcogenide nanodots （NDs） have received considerable interest. We report a facile bottom-up synthetic route for MoS2 NDs by using molybdenum pentachloride and L-cysteine as precursors in oleylamine. The synthesis of NDs with a narrow size distribution ranging from 2.2 to 5.3 nm, was tailored by controlling the reaction time. Because of its coating characteristics, oleyalmine leads to uniformity and monodispersity of the NDs. Moreover, the NDs synthesized have large specific surface areas providing active sites. Graphene possesses outstanding conductivity. Combining the advantages of the two materials, the 0D/2D material exhibits superior electrochemical performance because of the 2D permeable channels for ion adsorption, energy storage, and conversion. The as-prepared MoS2/rGO （-2.2 nm） showed a stable capacity of 220 mAh.g-1 after 10,000 cycles at the current density of 20 A.g-1. Furthermore, a reversible capacity -140 mAh·g-1 was obtained at a much higher current density of 40 A.g-L Additionally, this composite exhibited superior catalytic performance evidenced by a small overpotential （222 mV） to afford 10 ***-2, and a small Tafel slope （59.8 mV-decade-1） with good acid-stability. The facile approach may pave the way for the preparation of NDs with these nanostructures for numerous applications.

关键词： MoS2 nanodots size-controlled monodisperse electrochemical properties

Adaptive TDMA slot assignment protocol for vehicular ad-hoc networks

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2013年第1期20卷 11-18,25页

作者： YANG Wei-dong li pan liU yan ZHU Hong-song College of Information Science and Engineering Henan University of Technology State Key Laboratory of Information Security Institute of Information Engineering the Chinese Academy of Sciences Software and Microelectronics Peking University

This paper proposes a novel adaptive time division vehicular ad-hoc networks. ATSA divides different sets multiple access （TDMA） slot assignment protocol （ATSA） for of time slots according to vehicles moving in opposite directions. When a node accesses the networks, it choices a frame length and competes a slot based on its direction and location to communication with the other nodes. Based on the binary tree algorithm, the frame length is dynamically doubled or shortened, and the ratio of two slot sets is adjusted to decrease the probability of transmission collisions. The theoretical analysis proves ATSA protocol can reduce the time delay at least 20% than the media access control protocol for vehicular ad-hoc networks （VeMAC） and 30% than the ad-hoc. The simulation experiment shows that ATSA has a good scalability and the collisions would be reduced about 50% than VeMAC, channel utilization is significantly improved than several existing protocols.

关键词： media access control (MAC) protocol TDMA slot assignment adaptive frame length binary tree

Comparative study on microstructure evolution and failure mechanisms of ordinary and refurbished EB-PVD TBC under cyclic oxidation

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2023年第9期12卷 1805-1820页

作者： pan li Xiaochao Jin Pin Lu Delin liu Rende Mou Xueling Fan Xi’an Key Laboratory of Extreme Environmental Serviceability and Protection Technologies School of Aerospace EngineeringXi’an Jiaotong UniversityXi’an 710049China AECC Beijing Institute of Aeronautical Materials Beijing 100095China

Refurbishment of thermal barrier coating(TBC)has become a valuable technique to prolong the service life of high-temperature *** study investigates the effect of the refurbishment process(coating removal and recoating)on the microstructure evolution and physical properties of TBC,including oxidation characteristics,element diffusion behavior,and crack failure *** results showed that a certain amount of interdiffusion zone(IDZ)with Cr-rich would be retained in DD6 superalloy substrate after coating *** microstructure of the refurbished specimens showed equiaxedβ-NiAl phases,while the ordinary specimens have elongated grain shapes with a high aspect ***,mixed oxides in the refurbished TBC specimens were earlier observed during cyclic oxidation,with a greater thickness compared to ordinary TBC,due to the influence of BC layer phase *** growth mechanism of thermally grown oxide(TGO-Al_(2)O_(3)layer)in the refurbished TBC specimens was also different,resulting from the different mechanisms of mixed oxides ***,under cyclic oxidation with water quenching at 1100℃,the cracks in the refurbished specimen tend to occur in the mixed oxides layer,while the cracks in the ordinary specimen occur in the top coat(TC)layer,attributing to the earlier and thicker mixed oxides layer formed in refurbished specimens.

关键词： thermal barrier coating(TBC)systems coating removal refurbishment cyclic oxidation microstructure evolution failure mechanism

Numerical investigation on thermomechanical behavior of alumina–calcium hexaluminate refractories for purging plug

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2024年第2期31卷 389-400页

作者： li-ping pan Ya-wei li Fang-guan Tan Yi-chen Chen Yang-fan Xu Zhu He Bao-kuan li The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan430081HubeiChina National-Provincial Joint Engineering Research Center of High Temperature Materials and lining Technology Wuhan University of Science and TechnologyWuhan430081HubeiChina

Alumina–spinel refractories used in slit-type purging plugs are susceptible to cross-sectional damage,resulting in a serious mismatch between their service life and that of ***–calcium hexaluminate refractories have gradually become the new trend in purging plug materials with the development of refining *** thermomechanical damage of slit-type purging plugs with alumina–calcium hexaluminate refractory was investigated by the thermo-solid coupling *** with the polynomial fitting and design of experiments methods,the influence of thermophysical parameters on temperature and thermal stress of alumina–calcium hexaluminate refractories for purging plugs was systematically *** results show that the maximum thermal stress of the purging plugs appears during the stages of steel transporting and stirring,and the vulnerable parts are located above Y=0.323 *** thermal conductivity and the coefficient of thermal expansion of the material are the most sensitive parameters to the temperature and thermal stress inside the structure,*** addition of more calcium hexaluminate can relieve the stress concentration and large deformation around the ***,when the content of calcium hexaluminate is 47 wt.%and in the form of aggregate-binder,the temperature and thermal stress distribution inside the refractory are optimal,which can effectively improve the service life of the slit-type purging plug.

关键词： Purging plug Thermomechanical damage Refractory Design of experiments method Stress

配戴角膜塑形镜儿童停用低浓度阿托品前后近视进展情况

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

国际眼科杂志 2025年第1期25卷 134-139页

作者：王耀增李盼王瑾鹿子康中国陕西省西安市第一医院眼科 710002

目的:对比观察角膜塑形镜联合低浓度阿托品治疗的儿童在停用低浓度阿托品前后的近视进展情况,判断角膜塑形镜配戴者的停药反弹效应并根据瞳孔直径变化分析其产生原因。方法:前瞻性病例对照研究。纳入2022-01/06就诊于西安市第一医院应... 详细信息

目的:对比观察角膜塑形镜联合低浓度阿托品治疗的儿童在停用低浓度阿托品前后的近视进展情况,判断角膜塑形镜配戴者的停药反弹效应并根据瞳孔直径变化分析其产生原因。方法:前瞻性病例对照研究。纳入2022-01/06就诊于西安市第一医院应用角膜塑形镜并联合0.01%阿托品眼用凝胶控制近视儿童80例,1 a后根据是否停药分为停药组(A组,40例)和继续用药组(B组,40例),观察A组儿童停药前后1 a内的眼轴(AL)和等效球镜度(SE)变化,分析停药前后的近视进展情况,并对比观察A组和B组儿童2 a内的AL、瞳孔直径(PD)和SE变化,并分析PD与AL增长量的关系。结果:A组儿童在停药后0.5、1 a时AL分别增长0.17±0.23、0.29±0.18 mm,均大于停药前0.5、1 a(t=5.318、2.983,均P0.05)。联合用药时A组和B组在基线,随访0.5、1 a时的AL、PD变化均无差异(均P>0.05),随访1.5 a时A组的AL增长量大于B组(0.32±0.27 mm vs 0.26±0.20 mm,t=7.363,P<0.001),PD小于B组(3.60±1.25 mm vs 4.12±1.92 mm,t=-7.541,P<0.001),随访2 a时A组的AL增长量大于B组(0.44±0.18 mm vs 0.32±0.14 mm,t=5.709,P<0.001),PD小于B组(3.67±1.31 mm vs 4.02±1.67 mm,t=-4.281,P<0.001)。2 a内每0.5 a及每1 a随访时线性回归分析显示,PD和AL增长量呈负相关(R^(2)=-0.156、-0.190,均P<0.001)。结论:配戴角膜塑形镜的儿童停用低浓度阿托品后,AL较停药前增长较快,PD缩小而SE变化不大。较继续用药的情况相比,停止用药会导致AL进展较快而屈光度变化不大,且在配戴角膜塑形镜时瞳孔直径越大AL进展越慢。

关键词：角膜塑形镜低浓度阿托品近视眼轴等效球镜度瞳孔直径

Refined symmetry-resolved Page curve and charged black holes

在线全文

学校读者我要写书评

暂无评论

Chinese Physics C 2024年第5期48卷 134-140页

作者：李磐凌意 Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China School of Physics University of Chinese Academy of SciencesBeijing 100049China

The Page curve plotted using the typical random state approximation is not applicable to a system with conserved quantities,such as the evaporation process of a charged black hole,during which the electric charge does not macroscopically radiate out with a uniform *** this context,the symmetry-resolved entanglement entropy may play a significant role in describing the entanglement structure of such a *** attempt to impose constraints on microscopic quantum states to match the macroscopic phenomenon of charge radiation during black hole ***,we consider a simple qubit system with conserved spin/charge serving as a toy model for the evaporation of charged black *** propose refined rules for selecting a random state with conserved quantities to simulate the distribution of charges during the different stages of evaporation and obtain refined Page curves that exhibit distinct features in contrast to the original Page *** find that the refined Page curve may have a different Page time and exhibit asymmetric behavior on both sides of the Page *** refined Page curves may provide a more realistic description for the entanglement between the charged black hole and radiation during the evaporation process.

关键词： quantum entanglement Page curve charged black hole black hole evaporation Hawking radiation Schwinger effect random state average entropy

THE WALL EFFECT ON VENTILATED CAVITATING FLOWS IN CLOSED CAVITATION TUNNELS

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2008年第5期20卷 561-566页

作者： CHEN Xin LU Chuan-jing li Jie pan Zhan-cheng Department of Engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China

For ventilated cavitating flows in a closed water tunnel, the wall effect may exert an important influence on cavity shape and hydrodynamics, An isotropic mixture multiphase model was established to study the wall effect based on the RANS equations, coupled with a natural cavitation model and the RNG k-ε turbulent model. The governing equations were discretized using the finite volume method and solved by the Gauss-Seidel linear equation solver on the basis of a segregation algorithm. The algebraic multigrid approach was carried through to accelerate the convergence of solution. The steady ventilated cavitating flows in water tunnels of different diameter were simulated for a conceptual underwater vehicle model which had a disk cavitator. It is found that the choked cavitation number derived is close to the approximate solution of natural cavitating flow for a 3-D disk. The critical ventilation rate falls with decreasing diameter of the water tunnel. However, the cavity size and drag coeflicient are rising with the decrease in tunnel diameter for the same ventilation rate, and the cavity size will be much different in water tunnels of different diameter even for the same ventilated cavitation number.

关键词： ventilated cavitation water tunnel choked cavitation number critical ventilation rate

Nitrogen and fluorine co-doped graphene for ultra-stable lithium metal anodes

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第8期17卷 7212-7220页

作者： pan li Yifan liu Xujian Bao Jinghao Xie Zhao li Hongcheng li Qiang Ren Xiaomiao Feng Yue Hu Yanwen Ma State Key Laboratory for Organic Electronics and Information Displays(KLOEID)and Jiangsu Key Laboratory for Biosensors Institute of Advanced Materials(IAM)Nanjing University of Posts and TelecommunicationsNanjing 210023China Key Laboratory of Carbon Materials of Zhejiang Province College of Chemistry and Materials EngineeringWenzhou UniversityWenzhou 325000China

The heteroatom doping strategies have been utilized to effectively improve the performance of the carbon-based hosts,such as graphene,for lithium(li)metal in high energy density lithium metal ***,solely doped graphene hosts often need the assistance of other materials with either better lithiophilicity or electronic conductance to achieve smooth and efficient deposition of li,which adds extra weight or ***,graphene co-doped by nitrogen and fluorine(NFG)is employed as a stable host for li,where the N-doping provides lithiophilicity and electronic conductivity lacked by F-doping and the F-doping facilitates fast formation of solid electrolyte interphase(SEI)retarded by *** well regulation of li plating/stripping and SEI formation is verified by quickly stabilized and small-magnitude voltage hysteresis,which stands out in li hosts based on doped graphene and leads to excellent long-term cycling performance of NFG based electrodes.A voltage hysteresis of 20 mV is observed for more than 850 h in the symmetrical *** remarkable efficiency of lithium usage is confirmed by the highcapacity retention of a full cell paired with liFePO_(4)(LFP),which exceeds 70%after 500 *** work presents an innovative perspective on the control of li plating/stripping by simultaneously introducing two kinds of dopants into graphene and paving the way for exploring practical li metal batteries.

关键词： Co-doped graphene lithium metal anode dendrite suppression lithiophilic skeleton solid electrolyte interphase(SEI)formation

All-nanofiber self-powered PTFE/PA66 device for real-time breathing monitor by scalable solution blow spinning technology

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 Research 2022年第9期15卷 8458-8464页

作者： pan li Yibo liu Han Zhang Zhiping Hu Luna Jia Dongkui liu Lu Yu Bo li Youwei Yao School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Institute of Materials Research Tsinghua Shenzhen International Graduate SchoolShenzhen 518055China

All-nanofiber self-powered device was fabricated using simple,low-cost,safe,and scalable solution blow spinning(SBS)technology for real-time respiratory monitor and timely identification of respiratory obstruction ***(PTFE)and polyamide-66(PA66)nanofibers were selected as triboelectric pairs,owing to strong ability to gain electrons of PTFE and supply electrons of ***(ethylene oxide)(PEO)was added to regulate spinning solution viscosity and prepare PTFE/PEO nanofibers,and the morphology and diameter distribution of nanofibers were *** nanofiber film was obtained after the decomposition of PEO in PTFE/PEO nanofiber and melt flow of PTFE pellets in a limited region,and possessed a tensile strength of 1.05 MPa and elongation at a break of 288.58%.Later,PTFE/PA66 all-nanofiber self-powered device was constructed containing PA66 nanofibers,and Au deposition film was used as electrodes by magnetron *** as-obtained device showed robust electrical performance with an open circuit voltage of~110 V at a loading force of 10 N,a short-circuit current of~5 uA at a loading force of 10 N and a frequency of 4 Hz,a maximum power density of 562 mW·m^(–2),and a current of 3.1 uA at a loading resistance of 30 MΩ.Based on the triboelectric mechanism,the device possessed stable response and effective sensibility for stimuli,was used to monitor human breathing conditions,prevent suffocation,and distinguish slow,normal,and fast breathing,with an output voltage of~0.08 V perceived in one normal respiratory circle.

关键词： polytetrafluoroethylene(PTFE) nanofibers triboelectric flexible electronics