检索结果-南通市图书馆

Distinct MLT asymmetry of auroral kilometric radiation observed by the FAST satellite

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2025年第1期9卷 188-193页

作者： JiaWen Tang Sai Zhang FuLiang Xiao HongMing Yang si Liu YiHua He chang Yang YuYue Jin ZhouKun Deng Ping Li Archie James Johnston School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410114China Hunan Province Higher Education Key Laboratory of Modeling and Monitoring on the Near-Earth Electromagnetic Environments Changsha University of Science and TechnologyChangsha 410114China School of Electrical and Information Engineering Changsha University of Science and TechnologyChangsha 410114China

Auroral Kilometric Radiation(AKR)is a common radio emission,which can contribute to the magnetosphere−ionosphere−atmosphere *** emissions have been observed in all magnetic planet magnetospheres of the solar *** this study,using observations from the FAST satellite from 30 August 1996 to 9 September 2001,the distribution of AKR in altitude=500−4500 km and invariant latitude(|ILAT|)=60°−80°has been analyzed.63045 AKR samples have been identified with~48%(52%)samples on the dayside(nightside).Of considerable interest,there is a distinct MLT asymmetry with the high occurrence rate in MLT=05−08 and 18−22(02−05 and 12−17)in the northern(southern)*** distinct MLT asymmetry is associated with the direction of Bxof the interplanetary magnetic *** addition,the occurrence rate on the nightside clearly increases as the index *** study further enriches *** and understanding of AKR in the magnetosphere as well as other similar radio emissions.

关键词： asymmetry auroral kilometric radiation interplanetary magnetic field

机器学习在智能反射面辅助的通信系统中的应用综述

在线全文

学校读者我要写书评

暂无评论

北京工业大学学报 2025年第1期51卷 87-99页

作者：司鹏搏李双缘刘畅李萌北京工业大学信息学部北京100124 先进信息网络北京实验室北京100124

智能反射面(intelligent reflecting surfaces,IRS)可以通过大量低成本的无源反射元件巧妙地调整信号反射,从而动态改变无线信道,提高通信性能,目前已成为无线通信研究的焦点。然而,由于IRS的加入,整个通信系统变得更加复杂,系统的动态... 详细信息

智能反射面(intelligent reflecting surfaces,IRS)可以通过大量低成本的无源反射元件巧妙地调整信号反射,从而动态改变无线信道,提高通信性能,目前已成为无线通信研究的焦点。然而,由于IRS的加入,整个通信系统变得更加复杂,系统的动态性也更高,使通信系统面临着许多新的挑战。机器学习(machine learning,ML)具有很强的数据处理与自适应能力,能够不断适应变化的环境和需求,可以很好地应对通信系统中的许多挑战。因此,使用ML解决IRS辅助的通信系统中的问题,已经成为当前研究的重点。基于此,对ML在IRS系统中的应用进行了系统性的概述,从IRS辅助的通信系统中存在的问题入手,分别从反射因子的设计与优化、信道处理与建模、资源分配和管理、安全性增强4个方面对ML在IRS系统中的应用进行阐述和分析,并讨论了将ML应用在IRS系统中的优势及未来的发展趋势与挑战。

关键词：智能反射面(intelligent reflecting surfaces,IRS) 无线通信反射因子信道资源分配通信安全机器学习(machine learning,ML)

Preparation and characterization of SMA/S-POSS hybrid membranes for direct methanol fuel cell applications

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

Rare Metals 2006年第z1期25卷 224-228页

作者： chang young-wook Department of Chemical Engineering Hanyang University AnSan 425-791 South Korea

A novel sulfonated polyhedral oligomeric silsesquioxane(S-POSS) monomer was synthesized successfully in this article. S-POSS acted as a donor of sulfonic acid group and reacted with poly(styrene-co-maleic anhydride) (SMA). FT-IR spectroscopy confirmed the modification through introduction of peaks characteristic of ester linkages and carboxylic groups. The SMA/S-POSS hybrid membranes were fabricated from different S-POSS contents. The proton conductivity and methanol permeability of the hybrid membranes were studied with changing S-POSS content from 5wt.% to 30wt.%. It was found that the proton conductivity and the methanol permeability were dependent on the S-POSS content. Both of proton conductivity and methanol permeability properties improve with increasing S-POSS content. The proton conductivities of the hybrid membranes are in the range of 10-3-10-2 S·cm-1, and the range of methanol permeabilities was between 10-8 and 10-7 cm2·s-1. The membranes show good thermal properties characterized by thermogravimetric analysis (TGA).

关键词： SMA sulfonated polyhedral oligomeric silsesquioxane proton conductivity methanol permeability

Bi-directional and concurrent proof of ownership for stronger storage services with de-duplication

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2018年第3期61卷 84-94页

作者： Taek-young YOUN Ku-young chang Electronics and Telecommunications Research Institute

In storage service, data de-duplication is a specialized technique for eliminating duplicate copies of repeating data in storage. Especially, client-side de-duplication has more merits than server-side deduplication since they can improve both the space efficiency and the communication bandwidth. For secure client-side de-duplication, we need a way to prove the ownership of a file to be stored. In the upload step,the server should verify the ownership of a client to give the right of the file without uploading it. On the contrary, the client also want to verify the retrievability for the file since he will delete it from his storage after protocol execution. Existing proof of ownership techniques have been designed for server's need. In this paper, we first point out that we need the second property in client's view point, and give a very simple and practical solution which can support the server and the client to prove that they have the same file. We first describe a generic strategy which can help us to construction a bi-directional and concurrent proof of ownership technique from an ordinary proof of ownership technique, and then give an efficient hash-based scheme with security proof in the random oracle model.

关键词： cloud storage secure de-duplication data out-source proof of ownership bi-directional and concurrent proof

Room-temperature giant magnetotranstance effect in single-phase multiferroics

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2021年第3期64卷 105-110页

作者： Yan-Fen chang young Sun Beijing National Laboratory for Condensed Matter Physics and Beijing Advanced Innovation Center for Materials Genome Engineering Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Science University of Chinese Academy of SciencesBeijing 100190China Center of Quantum Materials and Devices Chongqing UniversityChongqing 401331China

single-phase multiferroic materials are usually considered useless because of the weak magnetoelectric effects,low operating temperature,and small electric polarization induced by magnetic *** a result,current studies on applications of the magnetoelectric effects are mainly focusing on multiferroic heterostructures and *** we report a room-temperature giant effect in response to external magnetic fields in single-phase multiferroics.A low magnetic field of 1000 Oe applied on the spin-driven multiferroic hexaferrites BaSrCo_(2) Fe_(11)AlO_(22) and Ba_(0.9)Sr_(1.1)Co_(2) Fe_(11)AlO_(22)is able to cause a huge change in the linear magnetoelectric coefficient(α_(E)=dE/dH) by several orders,leading to a giant magnetotranstance(GMT) effect at room *** GMT effect is comparable to the well-known giant magnetoresistance(GMR) effect in magnetic multilayers,and thus opens up a door toward practical applications for single-phase multiferroics.

关键词： multiferroic magnetoelectric effect transtor

Evaluation the Properties of Titanium Matrix Composites by Melting Route Synthesis

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2008年第1期24卷 105-109页

作者： Bong-Jae Choi si-young Sung Myoung-Gyun Kim young-Jig Kim Department of Advanced Materials Engineering Sungkyunkwan University SuwonKorea Department of Advanced Materials Engineering Sungkyunkwan University SuwonKorea Materials & Processing Engineering CenterR&D DivisionKorea Automotive Technology InstituteChonanChungnamKorea Research Institute of Industrial Science and Technology Pohang Korea

The main purpose of this study is an in-situ synthesis of （TiB＋TiC） hybrid titanium matrix composites （TMCs） by vacuum induction melting method and to verify its mechanical *** melting route was adopted to synthesize the commercial pure titanium （cp Ti） and granular boron carbide （B-4C）.The reinforcements,the fraction of 10 ***,were formed by adding 1.88 wt pct B-4C to cp *** in-situ synthesis of TMCs,electron probe micro-analysis elemental mapping was carried out to confirm the distribution and shape of *** cone-on-disk type sliding wear test was also done for the identification of *** is concluded that （TiB＋TiC） hybrid TMCs can be in-situ synthesized and has better wear properties than H13.

关键词： Titanium matrix composites H13 In-situ Wear

Irritable bowel syndrome:The evolution of multi-dimensional looking and multidisciplinary treatments

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2014年第10期20卷 2499-2514页

作者： Full-young chang Environmental Health and Safety Office and Division of Gastroenterology Taipei Veterans General Hospitaland National Yang-Ming University School of Medicine Taipei 11217 Taiwan

Irritable bowel syndrome(IBS)is common in the *** the putative pathogeneses,gut dysmotility results in pain and disturbed *** latter is probably caused by the effect of abnormal gut water *** interaction between abnormal gas accumulation,abdominal pain and bloating remains *** hypersensitivity and its modification along with the central transmission are the characteristics of IBS *** identification of biologic markers based on genetic polymorphisms is *** gut microbiota may alter epithelial permeability to activate nociceptive sensory pathways which in turn lead to *** food constituents may exacerbate bowel *** impact of adult and childhood abuses on IBS is *** the concept of biopsychosocial dysfunction can integrate multidimensional *** plus stool consistency modifiers to treat the major symptoms and defecation are the first-line drug *** drugs targeting receptors governing bowel motility,sensation and secretion can be considered,but clinicians must be aware of their potential serious side *** drugs and modalities may be the final options for treating intractable *** of multi-species preparations are safe and worth to be considered for the *** are promising but their longterm safety and effectiveness are *** therapy including exclusion of certain food constituents is an economic *** relatively safe complementary and alternative medicines(CAMs)may be optional to those patients who failed classical *** conclusion,IBS is a heterogeneous disorder with multidimensional *** medicines with multidisciplinary approaches using different classes of drugs,psychiatric measures,probiotics and antibiotics,dietary therapy,and finally CAMs,can be considered.

关键词： Antispasmodics Biopsychosocial dysfunction Comorbidity Genetics Irritable bowel syndrome Microbiota Probiotics Visceral hyperalgesia

A general solution for Stokes flow and its application to the problem of a rigid plate translating in a fluid

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

Acta Mechanica sinica 2015年第1期31卷 32-44页

作者： Xiang-Yu Li si-Cong Ren Qi-chang He School of Mechanics and Engineering Southwest Jiaotong University School of Mechanical Engineering Southwest Jiaotong University Universit'e Paris-Est Laboratoire Mod'elisation et Simulation Multi Echelle UMR 8208 CNRS 5 Boulevard Descartes77454 Marne-la-Vall'ee France

A general solution for 3D Stokes flow is given which is different from, and more compact than the exist ing ones and more compact than them in that it involves only two scalar harmonic functions. The general solution deduced is combined with the potential theory method to study the Stokes flow induced by a rigid plate of arbitrary shape trans lating along the direction normal to it in an unbounded fluid. The boundary integral equation governing this problem is derived. When the plate is elliptic, exact analytical results are obtained not only for the drag force but also for the ve locity distributions. These results include and complete the ones available for a circular plate. Numerical examples are provided to illustrate the main results for circular and ellip tic plates. In particular, the elliptic eccentricity of a plate is shown to exhibit significant influences.

关键词： Stokes flow 3D general solutions Potentialtheory method Circular plate Elliptic plate

Studies on Micellization of a Polystyrene-b-poly(acrylic acid) Copolymer in Aqueous Media by Pyrene Fluorescence

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2003年第1期14卷 39-41页

作者： Zhi Huai si Guo chang WANG 等 StateKeyLaboratoryofFunctioinalPolymerMaterialsforAdsorptionandSeparationandInstituteofPolymerChemistry NankaiUniversityTianjin300071 StateKeyLaboratoryofFunctioinalPolymerMat

Pyrene probe and TEM have been employed to investigate the behavior of a polystyrene-b-poly(acrylic acid) (PS-b-PAA) copolymer in aqueous solution. A significant annealing temperature effect on the I1/I3 ratio of pyrene was observed and was interpreted in terms of the morphological change of micellar cores. Annealing at a temperature higher than the glass transition temperature (Tg) of PS leads to densification of the hydrophobic core.

关键词： Polystyrene-b-poly(acrylic acid) micelle fluorescence pyrene.