检索结果-南通市图书馆

Heterostructure design of hydrangea-like Co_(2)P/Ni_(2)P@C multilayered hollow microspheres for high-efficiency microwave absorption

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 Materials Science & Technology 2024年第14期181卷 104-114页

作者： Wei Wang kai Nan Hao Zheng Qingwei Li yan Wang School of Materials and Chemical Engineering Xi’an Technological UniversityXi’an 710021China Department of Joint Surgery Honghui HospitalXi’an Jiaotong UniversityXi’an 710054China

Structural design and elemental doping are research hotspots for the preparation of lightweight absorbers with high absorption performance and low filling ***,a P-doped hydrangea-like layered compos-ite(Co_(2)P/Ni_(2)P@C)encapsulated with Ni-LDH was successfully synthesized by solvothermal method fol-lowed by *** defects generated by P doping and the generation of multilayered nonuni-form interfaces enhance the dielectric loss induced by ***,the magnetic phos-phides induce magnetic loss and modulate the dielectric properties of the carbon matrix to enhance the conductive *** multilayered hollow structure of this composite promotes the scattering and reflec-tion of electromagnetic waves and optimizes the impedance *** a result,the multilayered hollow Co_(2)P/Ni_(2)P@C composite exhibits an optimum reflection loss value(RL)of–64.6 dB at 15.1 GHz with a thickness of 2 mm and a filler ratio of only 10 wt%.The radar cross-section(RCS)attenuation further demonstrates that the material can dissipate microwave energy in practical ***,this work provides an effective development strategy for the design of multilayered high-performance electromagnetic wave(EMW)absorbers doped with strongly polarized elements.

关键词： Microwave absorption P-doping Radar cross section Multilayered hollow architecture Hydrangea-like

Spherical Confinement Generates Entropic Force to Accelerate Polymer Chain Detachment

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 Journal of Polymer Science 2024年第3期42卷 407-416,I0010页

作者： Yu-Shan Zheng Jian-Ping Zhou yan Xu kai Li Mechanical Engineering Xinjiang UniversityUrumqi 830002China

To understand the dynamic process of polymer detachment, it is necessary to determine the mean detachment time of a single breakable link, which is modeled as a spring. Normally, this time can be viewed as the escape of a Brownian particle from the potential well of the spring. However, as the free dangling length of the polymer chain increases, the conformational entropy of the chain is affected by geometric confinement. It means that the wall exerts a repulsive force on the chain, resulting in accelerated link detachment from a macroscopic perspective. In this work, we investigate the effect of entropy on the detachment rate in the case where the substrate is spherical. We demonstrate that spherical confinement accelerates chain detachment both inside and outside the sphere. An analytical expression for the mean detachment time of breakable links is given, which includes an additional pre-factor that is related to the partition function. Additionally, we analyze the expressions for entropic forces inside the sphere, outside the sphere, and on a flat wall, comparing their magnitudes to explain the difference in mean detachment time.

关键词： Polymer detachment Breakable link Entropic force Mean first passage time

A Secure IoT Firmware Update Scheme Against SCPA and DoS Attacks

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2021年第2期36卷 419-433页

作者： yan-Hong Fan Mei-Qin Wang yan-Bin Li kai Hu Mu-Zhou Li School of Cyber Science and Technology Shandong UniversityQingdao 266237China Key Laboratory of Cryptologic Technology and Information Security(Shandong University) Ministry of Education Qingdao 266237China

In the IEEE S&P 2017,Ronen et *** side-channel power analysis(SCPA)and approximately 5000 power traces to recover the global AES-CCM key that Philip Hue lamps use to decrypt and authenticate new *** on the recovered key,the attacker could create a malicious firmware update and load it to Philip Hue lamps to cause Internet of Things(IoT)security *** by the work of Ronen et al.,we propose an AES-CCM-based firmware update scheme against SCPA and denial of service(DoS)*** proposed scheme applied in IoT terminal devices includes two aspects of design(i.e.,bootloader and application layer).Firstly,in the bootloader,the number of updates per unit time is limited to prevent the attacker from acquiring a sufficient number of useful traces in a short time,which can effectively counter an SCPA ***,in the application layer,using the proposed handshake protocol,the IoT device can access the IoT server to regain update permission,which can defend against DoS ***,on the STM32F405+M25P40 hardware platform,we implement Philips'and the proposed modified *** results show that compared with the firmware update scheme of Philips Hue smart lamps,the proposed scheme additionally requires only 2.35 KB of Flash memory and a maximum of 0.32 s update time to effectively enhance the security of the AES-CCM-based firmware update process.

关键词： Internet of Things firmware update authenticated encryption side-channel power analysis denial of service

The amelioration of degraded larch(Larix olgensis)soil depends on the proportion of Aralia elata litter in *** agroforestry systems

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 Forestry Research 2023年第4期34卷 1065-1076页

作者： Pingzhen Gao Jiaojun Zhu Qiaoling yan kai yang Jinxin Zhang Qingyuan Forest CERN National Observation and Research StationShenyang 110016Liaoning ProvinceChina CAS Key Laboratory of Forest Ecology and Management Institute of Applied EcologyShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China

Research has indicated that introducing Aralia elata into larch plantations forms an agroforestry system which could provide economic benefi ts for local farmers and improve degraded ***,the impact of litter mixtures on soil chemical and microbial properties in this agroforestry system are unclear,which limits effi cient management of the agroforestry system.A 365-d incubation experiment examined the eff ect of litter mixtures of diff erent proportions of larch(L)and ***(A)on soil chemical and microbial *** results show that levels of mineral N,available P,microbial biomass carbon and nitrogen,cumulative C mineralization,and activities of hydrolases and oxidases increased with an increase of *** in the litter *** of total soil carbon,nitrogen,and phosphorous did not change(except for total nitrogen).Compared with larch litter alone,levels of mineral N,available P,microbial biomass carbon and nitrogen,cumulative C mineralization,and the activities of hydrolases and oxidases increased by 7.6–433.5%.Most chemical and microbial properties were positively correlated with mixed litter proportions and the initial levels of N,P,K,Ca,Mg,Mn,Zn and Cu in the litter,while negatively correlated with the initial concentrations of C,Fe and lignin,C/N and lignin/N *** results indicate that *** litter can improve degraded larch soil and the degree depends on the proportion of *** litter in the litter mixtures.

关键词： Larch-based agroforestry Incubation experiment Litter mixtures Litter quality Soil properties

Deformation behavior of fine-grained 5083 Al alloy at elevated temperature

在线全文

学校读者我要写书评

暂无评论

Transactions of Nonferrous Metals Society of China 2009年第S02期19卷 307-311页

作者： ZHANG kai-feng yan Hong-hua School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

The microstructure evolution of the fine-grained 5083 Al alloy was investigated in annealing temperature range of 150−300℃.Then the effects of the different annealed microstructures on high-temperature deformation behavior were further *** results indicate that the initial recrystallization temperature is about 200℃.By tensile tests at 380−570℃and in strain rate range of 4.17×10^(−4)−1.0×10^(−2) s^(−1),the optimum superplastic parameters are obtained as follows:the annealed temperature 250℃,the tensile temperature 550℃and the strain rate 4.17×10^(−4) s^(−1).With the aid of scanning electronic microscopy(SEM),the fractography of the alloy after the superplastic deformation was *** results reveal that intergranular cavities with fine size and homogeneous distribution are beneficial to superplastic deformation.

关键词： fine-grained 5083 Al alloy annealing superplastic deformation

Cyproheptadine Regulates Pyramidal Neuron Excitability in Mouse Medial Prefrontal Cortex

在线全文

学校读者我要写书评

暂无评论

Neuroscience Bulletin 2018年第5期34卷 759-768页

作者： yan-Lin He kai Wang Qian-Ru Zhao yan-Ai Mei Institutes of Brain Science State Key Laboratory of Medical Neurobiology and School of Life Sciences Fudan University

Cyproheptadine （CPH）, a first-generation anti- histamine, enhances the delayed rectifier outward K＋ current （IK） in mouse cortical neurons through a sigma-1 receptor-mediated protein kinase A pathway. In this study, we aimed to determine the effects of CPH on neuronal excitability in current-clamped pyramidal neurons in mouse medial prefrontal cortex slices. CPH （10 μmol/L） significantly reduced the current density required to generate action potentials （APs） and increased the instan- taneous frequency evoked by a depolarizing current. CPH also depolarized the resting membrane potential （RMP）, decreased the delay time to elicit an AP, and reduced the spike threshold potential. This effect of CPH was mim- icked by a sigma-1 receptor agonist and eliminated by an antagonist. Application of tetraethylammonium （TEA） to block IK channels hyperpolarized the RMP and reduced the instantaneous frequency of APs. TEA eliminated the effects of CPH on AP frequency and delay time, but had no effect on spike threshold or RMP. The current-voltage relationship showed that CPH increased the membrane depolarization in response to positive current pulses and hyperpolarization in response to negative current pulses, suggesting that other types of membrane ion channels might also be affected by CPH. These results suggest that CPH increases the excitability of medial prefrontal cortex neurons by regulating TEA-sensitive IK channels as well as other TEA-insensitive K＋ channels, probably ID and inward-rectifier Kir channels. This effect of CPH may explain its apparent clinical efficacy as an antidepressant and antipsychotic.

关键词： Cyproheptadine Neuronal excitability Te-traethylammonium-sensitive Ik cortical neurons Sigma-1 receptor

GNSS vulnerabilities:simulation,verification,and mitigation platform design

在线全文

学校读者我要写书评

暂无评论

Geo-Spatial Information Science 2013年第3期16卷 149-154页

作者： Xin ZHAO Xingqun ZHAN kai yan School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China

This paper introduces the design and construction of global navigation satellite systems(GNSS)vulnerability simulation,verification,and mitigation *** platform contains five modules:simulation of the signal-in-space environment,simulation of the vulnerabilities in the space segment,signal quality monitoring and data processing,vulnerability assessment and validation,and integrated *** provides a set of integrated simulations of different types of interference in the GNSS signal propagation domain,including electromagnetic interference,atmospheric disturbances,multipath,and interference in the inter-satellite *** paper focuses on the design of the main system modules and testing through an experimental *** results demonstrate both the effectiveness and realism of the modules and overall platform.

关键词： GNSS vulnerability spoofing jamming ionosphere delay multipath effect

Alternating Direction Method of Multipliers for l_(1)-l_(2)-Regularized Logistic Regression Model

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 the Operations Research Society of China 2016年第2期4卷 243-253页

作者： yan-Qin Bai kai-Ji Shen Department of Mathematics Shanghai UniversityShanghai 200444China

Logistic regression has been proved as a promising method for machine learning,which focuses on the problem of *** this paper,we present anl_(1)-l_(2)-regularized logistic regression model,where thel1-norm is responsible for yielding a sparse logistic regression classifier and thel_(2)-norm for keeping betlter classification *** solve thel_(1)-l_(2)-regularized logistic regression model,we develop an alternating direction method of multipliers with embedding limitedlBroyden-Fletcher-Goldfarb-Shanno(L-BFGS)***,we implement our model for binary classification problems by using real data examples selected from the University of California,Irvine Machines Learning Repository(UCI Repository).We compare our numerical results with those obtained by the well-known LIBSVM and SVM-Light *** numerical results show that ourl_(1)-l_(2)-regularized logisltic regression model achieves better classification and less CPU Time.

关键词： Classification problems Logistic regression model Sparsity Alternating direction method of multipliers

Endodontic treatment of the maxillary first molar with palatal canal variations: A case report and review of literature

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Clinical Cases 2022年第32期10卷 12036-12044页

作者： kai Chen Xing Ran yan Wang Department of Stomatology Shanghai Tenth People's HospitalTongji University School of MedicineShanghai 200072China Department of Stomatology Shanghai Jiading District Center for Dental Disease Prevention and ControlShanghai 201899China Department of Stomatology Eye and Dental Diseases Prevention&Treatment of Pudong New AreaShanghai 201399China

BACKGROUND Root canal variations frequently occur in maxillary first molars,which greatly affects the success of its *** second mesiobuccal(MB)root canal is the most common root canal ***,only a few studies have been conducted on palatal root canal ***,we report the presence of two separate root canals in a palatal root of the maxillary first *** SUMMARY A 39-year-old woman complained of pain in the maxillary right region for 1 year,which recently *** examination revealed a poorly restored right maxillary first molar and caries detected at the filling *** and heat test results indicated severe pain in the right maxillary first *** patient was diagnosed with irreversible pulpitis,and subsequently,root canal treatment(RCT)was *** total,five root canals were found in the maxillary first molar,including two separate root canals in the palatal *** was successfully performed using an endodontic microscope and cone-beam computed tomography(CBCT).The CBCT image revealed a vertucci type I canal morphology in the distobuccal root,while the MB and palatal root canals were typeⅣ.At the 1-mo follow-up,the maxillary first molar was completely asy-mptomatic,and the X-ray results indicated a successful ***,the ceramic crown restoration was *** An endodontic microscope and CBCT are useful in effectively identifying and treating root canal variations.

关键词： Molar Root canal Endodontics Dental pulp cavity Pulpitis Case report