检索结果-南通市图书馆

Massive Preparation of Coumarone-indene Resin-based Hyper-crosslinked Polymers for Gas Adsorption

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2018年第10期36卷 1168-1174页

作者： Ke Tian Ting-Ting Zhu Ping lan Zheng-Chen Wu Wei Hu fei-fei Xie Lei Li College of Materials and Fujian Provincial Key Laboratory of Materials Genome Xiamen University Material and Textile College Jiaxing University

Hyper-crosslinked polymers （HCPs） are promising materials for gas capture and storage because of their low cost and easy preparation. In this work, we report the massive preparation of coumarone-indene resin-based hyper-crosslinked polymers via one-step Friedel-Crafts alkylation. Low-cost coumarone-indene resin serves as the new building block and chloroform is employed as both solvent and external crosslinker. A maximum surface area of 966 m2·g-1 is achieved, which is comparable with that of previously-reported coal tar-based porous organic polymers. Most importantly, a large number of heteroatoms including inherent oxygen atoms and introduced chlorine atoms in obtianed HCPs further enhance the interaction between specific sorbate molecule and adsorbent. Therefore, optimal structural and chemical property endow the new coumarone-indene resin-based HCPs with decent gas storage capacity （14.60 wt% at 273 K and 0.1 MPa for CO2; 1.18 wt% at 77.3 K and 0.1 MPa for H2）. These results demonstrate that new HCPs are potential candidates for applications in CO2 and H2 capture.

关键词： Coumarone-indene resin Friedel-Crafts alkylation Gas adsorption Microporous organic polymers

Dependence-Induced Risk: Security Metrics and Their Measurement Framework

在线全文

学校读者我要写书评

暂无评论

China Communications 2016年第11期13卷 119-128页

作者： Liqiang Zhang fei Yan bo Zhao Shouhuai Xu Computer School Wuhan University Key Lab of Aerospace Information Security and Trusted Computing Wuhan University State Key Lab of Software Engineering Wuhan University Department of Computer Science University of Texas at San Antonio

Despite the tremendous effort made by industry and academia,we are still searching for metrics that can characterize Cyberspace and system security risks. In this paper,we study the class of security risks that are inherent to the dependence structure in software with vulnerabilities and exhibit a "cascading" effect. We present a measurement framework for evaluating these metrics,and report a preliminary case study on evaluating the dependence-induced security risks in the Apache HTTP Server. The experiment results show that our framework can not only clearly analyze the root cause of the security risks but also quantitatively evaluate the attack consequence of the risks.

关键词： Cyberspace security security metrics exploitability surface attack conse quence risk assessment

Accessibility and Homology bounded Strong Unstable Foliation for Anosov Diffeomorphisms on 3-torus

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2017年第1期33卷 71-76页

作者： Yan REN Shao bo GAN Peng fei ZHANG School of Mathematical Sciences Peking University Department of Mathematics and Statistics Universityof Massachusetts

We give three equivalent conditions for non-accessibility of an Anosov diffeomorphism on the 3-torus with a partially hyperbolic splitting. Since accessibility is an open property, this gives a negative answer to Hammerlindl＇s question about homology boundedness of strong unstable foliation. Keywords Partially hyperbolic, accessible, homology bounded

关键词： Partially hyperbolic accessible homology bounded

Improving Image Copy-Move Forgery Detection with Particle Swarm Optimization Techniques

在线全文

学校读者我要写书评

暂无评论

China Communications 2016年第1期13卷 139-149页

作者： SHI Wenchang ZHAO fei QIN bo LIANG Bin School of Information Renmin University of China

Copy-Move Forgery(CMF) is one of the simple and effective operations to create forged digital ***,techniques based on Scale Invariant Features Transform(SIFT) are widely used to detect *** approaches under the SIFT-based framework are the most acceptable ways to CMF detection due to their robust ***,for some CMF images,these approaches cannot produce satisfactory detection *** instance,the number of the matched keypoints may be too less to prove an image to be a CMF image or to generate an accurate *** these approaches may even produce error *** to our observations,one of the reasons is that detection results produced by the SIFT-based framework depend highly on parameters whose values are often determined with *** values are only applicable to a few images,which limits their *** solve the problem,a novel approach named as CMF Detection with Particle Swarm Optimization(CMFDPSO) is proposed in this ***-PSO integrates the Particle Swarm Optimization(PSO) algorithm into the SIFT-based *** utilizes the PSO algorithm to generate customized parameter values for images,which are used for CMF detection under the SIFT-based *** results show that CMFD-PSO has good performance.

关键词： copy-move forgery detection SIFT region duplication digital image forensics

Multiuser beamforming based on max SINR for downlink spatial multiplexing MIMO

在线全文

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2007年第3期14卷 28-33页

作者： MA Peng-fei ZHENG Kan WANG Wen-bo Wireless Signal Processing and Network Laboratory Beijing University ofPosts and Telecommunications Beijing 100876 China

In this article, a method based on max signal interference noise ratio（SINR） criterion is proposed, to mitigate the interuser interference for downlink multiuser spatial multiplexing multi-input multi-output（MIMO） systems. Unlike the zero forcing （ZF） scheme in which the SNR is decreased when the interference is eliminated completely, max SINR method makes a compromise between noise and interuser interference. When the number of substreams is larger than the difference between the number of base station antennas and the sum of interference mobile station antennas, the ZF is infeasible An existing coordinated TX-RX block diagonalization（COOR BD） method uses preprocessing at the receiver to cancel the interuser interference. However, it cannot obtain more receive diversity gain because of the preprocessing. Analysis and simulation show that the max SINR scheme has better performance than the ZF method. Moreover, when the ZF is infeasible, the max SINR scheme can obtain more receive diversity gain than COOR BD in the two-user case.

关键词： array signal processing beamforming MIMO systems spatial multiplexing

Theoretical study of the electroactive bistable actuator and regulation methods

在线全文

学校读者我要写书评

暂无评论

International Journal of Smart and Nano Materials 2023年第1期14卷 36-56页

作者： Wenjie Sun Huwei Liang fei Zhang bo Li School of Mechanical and Precision Instrument Engineering Xi’an University of Technology710048Xi’anChina State Key Laboratory for Strength and Vibration of Mechanical Structures and School of Aerospace Xi’an Jiaotong University710049Xi’anChina CAS Center for Excellence in Nanoscience Beijing Key Laboratory of Micro-nano Energy and SensorBeijing Institute of Nano Energy and Nano SystemsChinese Academy of Sciences101400BeijingChina State Key Laboratory for Manufacturing System Engineering Shaanxi Key Lab for the Intelligent RobotsSchool of Mechanical EngineeringXi’an Jiaotong University710049Xi’anChina

Dielectric elastomer actuators have attracted growing interest for soft robot due to their large deformation and fast ***,continuous high-voltage loading tends to cause the electric breakdown of the actuator due to heat accumulation,and viscoelasticity complicates precise *** snap-through bistability of the Venus flytrap is one of the essential inspirations for bionic structure,which can be adopted to improve the shortcoming of dielectric elastomer actuators and develop a new actuation structure with low energy consumption,variable configuration,and multi-mode ***,in this paper,the structural design principles of electroactive bistable actuators are first presented based on the total potential energy of the *** that,a feasible design parameter region is provided,the influence of crucial parameters on the actuation stroke,trigger voltage,and actuation charge are ***,according to the coupling relationship between the bending stiffness and the bistable property of the actuator,the adjusting methods of bistable actuation are explored.A qualitative experiment was performed to verify the feasibility and correctness of the bistable design methodology and the actuation regulation *** study provides significant theoretical guidance and technical support for developing and applying dielectric elastomer actuators with multi-mode,high-performance,and long-life characteristics.

关键词： Dielectric elastomer bistable structure snap-through electromechanical actuation minimum energy structure

Plasmaspheric trough evolution under different conditions of subauroral ion drift

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

Science China(Technological Sciences) 2012年第5期55卷 1287-1294页

作者： HE fei ZHANG XiaoXin CHEN bo FOK MeiChing Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China National Center for Space Weather China Meteorological AdministrationBeijing 100081China NASA Goddard Space Flight Center GreenbeltMD 20771USA

The statistical characteristics of the subauroral ion drift (SAID) in the ionosphere and the plasmaspheric trough evolution under different conditions of SAID were investigated in this paper, based on 566 SAID events observed by Akebono, Astrid-2, DE-2, and Freja satellites. The relationships between the latitudinal location of SAID and the Kp, AL, and Dst indices for these events were also discussed. It was found that the SAID events happened mainly at invariant latitude (ILAT) of 60.4° and magnetic local time (MLT) of 21.6 MLT and that 92.4% of the events happened when the Kp index was below 5.0, indicating a medium geomagnetic activity. The latitudinal half-width of SAID varied from 0.5° to 3.0° with a typical half-width of 1.0°. The SAID would happen at low latitudes if the geomagnetic activity was high. The effects of SAID on equatorial outer plas- masphere trough evolutions were studied with the dynamic global core plasma model (DGCPM) driven by the statistical results of SAID signatures. It was noted that locations, shapes and density of troughs vary with ILAT, MLT, latitudinal width, cross polar cap potential and lifetime of SAID events. The evolution of a trough is determined by the extent of SAID electric field penetrating into plasmasphere and not all SAID events can result in trough formations.

关键词： subauroral ion drift plasmaspheric trough dynamic global core plasma model simulation

Recent advances in single metal atom-doped MoS_(2) as catalysts for hydrogen evolution reaction

在线全文

学校读者我要写书评

暂无评论

Tungsten 2020年第2期2卷 147-161页

作者： Rui Liu Hui‑Long fei Gong‑lan Ye College of Chemistry and Chemical Engineering Hunan UniversityChangsha 410082China State Key Laboratory for Chemo/Biosensing and Chemometrics Hunan UniversityChangsha 410082China

The development of low-cost and highly efficient electrocatalysts for hydrogen evolution reaction(HER)is critical to the wide-spread applications of water splitting *** recent years,many efforts are devoted to exploring HER catalysts with high activity and stability based on non-precious *** from the advantages of two-dimensional(2D)materials with unique physicochemical properties along with the single-atom catalysts with high activity,excellent stability and maximized atom utility efficiency,a new category of catalysts with 2D materials confining single atoms have shown great promises as high-performance HER *** this review,MoS_(2),as one of the typical 2D materials,doped with various single metal atoms as HER catalysts are fully discussed,including different synthetic strategies,catalytic performances and mechanisms toward HER as well as the major challenges ahead.

关键词： Molybdenum disulfide Single atom catalysts Hydrogen evolution reaction

Logic Bell state concentration with parity check measurement

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

Frontiers of physics 2019年第2期14卷 1-11页

作者： Jiu Liu lan Zhou Wei Zhong Yu-bo Sheng Institute of Quantum Information and Technology Nanjing University of Posts and TelecommunicationsNanjing 210003China School of Science Nanjing University of Posts and TelecommunicationsNanjing 210003China Key Lab of Broadband Wireless Communication and Sensor Network Technology (Ministry of Education) Nanjing University of Posts and TelecommunicationsNanjing 210003China

Logic qubit plays an important role in current quantum communication. In this paper, we propose an efficient entanglement concentration protocol (ECP) for a new kind of logic Bell state, where the logic qubit is the concatenated Greenber- Horne- Zeilinger (C-GHZ) state. Our ECP relies on the nondemolition polarization parity check (PPC) gates constructed with cross-Kerr nonlinearity, and can distill one pair of maximally entangled logic Bell state from two same pairs of less-entangled logic Bell states. Benefit from the nondemolition PPC gates, the concentrated maximally entangled logic Bell st ate can be remained for further application. Moreover, our ECP can be rcpea ted to further concentrate the less-entangled logic Bell state. By repeating the ECP. the total success probability can be effectively increased. Based on above features, this ECP may be useful in future long-distance quantum communication.

关键词： concatenated Greenber-Horne-Zeilinger (C-GHZ) state single photon cross-Kerr nonlinearity