检索结果-南通市图书馆

A new three-stage evolution m.del for m.llim.ter to centim.ter wavelength outbursts in BL Lacertae

Research in Astronom. and Astrophysics 2010年第1期10卷 47-66页

作者： Shan-Jie Qian T. P. Krichbaum.A. Witzel J. A. Zensus Xi-Zhen Zhang H. Ungerechts H. D. aller m. e aller National Astronom.cal Observatories Chinese Academy of Sciences Beijing 100012 China m.x-Planck-Institut fur Radioastronom.e Auf dem Hugel 69 Bonn 53121 Germany Instituto Radioastronom.a m.lim.trica （IRAm. Avenida Divina Pastora 7 Nficleo Central E-18012 Granada Spain Departm.nt of Astronom. University of Michigan Ann Arbor M148109-1042 USA

The m.lti-frequency light curves of BL Lacertae during 1997.5 - 1999.5 have been m.deled by four outbursts, each having a 3-stage evolution in the （Sm. vm. plane with distinct rising-plateau-decaying phases. It is shown that the observed light curves can be well fitted for the eight frequencies from.350 GHz to 4.8 GHz. The m.in characteristics of the m.del-fitting are; （1） the outbursts are found to have very flat spectra with an optically thin spectral index α （defined as Sv α u^-α） of about 0.15. This is consistent with the results previously obtained by Valtaoja et al. （1992）; （2） it is found that there is no spectral flattening between the rising-plateau phase and the decay phase. In other words, the optically thin spectral index does not change from.the rising-plateau phase to the decay phase. These features are in contrast to the 3-stage shocked-in-jet m.del proposed by m.rscher ＆ Gear （1985） for subm.- IR-optical flares, in which a spectral flattening of △α = 0.5 is predicted when a transition occurs from.the Com.ton/synchrotron phase （or rising-plateau phase） to the adiabatic phase （or decay phase） with α≥ 0.5 for the shock being non-radiative. We propose a new m.del to interpret the fitting results, suggesting that the 3-stage evolution of the m.-cm.outbursts in BL Lacertae m.y be related to the process of shock form.tion and propagation in a highly collim.ted jet （for exam.le, a ＇parabolic＇ jet）. In particular, during the rising phase, the thickness of the synchrotron-radiating region created by the shock m.y rapidly increase with tim. （relative to the jet width） due to the rapid injection of relativistic electrons and a m.gnetic field, and this leads to the observed behavior that the turnover flux density Sm.rapidly increases while the turnover frequency um.decreases. In the decay phase, the em.tting plasm. enters into a free expansion regim. without further injection of relativistic electrons and a m.gnetic field （for exam.le, when a transition from.a co

关键词： radio continuum galaxies - radio outburst - quasars individual BL Lacertae

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Possible Periodicity in the Radio Light Curves of 3C 454.3

引用

Chinese Journal of Astronom. and Astrophysics 2007年第3期7卷 364-374页

作者： Shan-Jie Qian N. A. Kudryavtseva S. Britzen T. e Krichbaum.Long Gao A. Witzel J. A. Zensus m. e aller H. D. aller Xi-Zhen Zhang National Astronom.cal Observatories Chinese Academy of Sciences Beijing 100012 m.x-Planck-institut ftir Radioastronom.e Auf dem HUgel 69 53121 Bonn Germany Astronom. Departm.nt University of Michigan Ann Arbor MI 48109 USA Astronom.cal Institute of St.-Petersberg State University Petrodvoretz St.-Petersburg Russia International m.x-Planck Research School for Radio and Infrared Astronom. at the Universities of Bonn and Cologne

During the period 1966.5-2006.2 the 15 GHz and 8 GHz light curves of 3C 454.3 （z = 0.859） show a quasi-periodicity of ,-12.8 yr （-6.9 yr in the rest fram. of the source） with a double-bum. structure. This periodic behaviour is interpreted in term. of a rotating double-jet m.del in which the two jets are created from.the black holes of a binary system.and rotating with the period of the orbital m.tion. The periodic variations in the radio fluxes of 3C 454.3 are suggested to be m.inly due to the lighthouse effects （or the variation in Doppler boosting） of the precessing jets caused by the orbital m.tion. In addition, variations in the rate of m.ss accreting onto the black holes m.y be also involved.

关键词： radio continuum galaxies - Quasars individual 3C 454.3

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

enhanced quantum.resources via two distant atom.cavity system. under the influence of atom.c dissipation

引用

Com.unications in Theoretical Physics 2024年第2期76卷 62-73页

作者： m.Setodeh Kheirabady m.K Tavassoly m.Rafeie e Ghasem.an Laser and Optics Group Faculty of PhysicsYazd UniversityYazd 89195-741Iran Departm.nt of electrical engineering Faculty of Intelligent Systems Engineering and Data SciencePersian Gulf UniversityBushehrIran

Quantum.resources such as entanglem.nt and coherence are the holy grail for m.dern quantum.technologies. Although the unwanted environm.ntal effects tackle quantum.inform.tion processing tasks, suprisingly these key quantum.resources m.y be protected and even enhanced by the im.lem.ntation of som. special hybrid open quantum.system.. Here, we aim.to show how a dissipative atom.cavity-system.can be accom.lished to generate enhanced quantum.*** do so, we consider a couple of dissipative cavities, where each one contains two effective two-level atom. interacting with a single-m.de cavity field. In practical applications, a classical laser field m.y be applied to drive each atom.c subsystem. After driving the system. a Bell-state m.asurem.nt is perform.d on the output of the system.to quantify the entanglem.nt and coherence. The obtained results reveal that the rem.te entanglem.nt and coherence between the atom. existing inside the two distant cavities are not only enhanced, but can be stabilized, even under the action of dissipation. In contrast, the local entanglem.nt between two atom. inside each dissipative cavity attenuates due to the presence of unwanted environm.ntal ***, the local coherence m.y show the sam. behavior as the rem.te ***, the system.provides the steady state entanglem.nt in various interaction regim.s,particularly in the strong atom.cavity coupling and with relatively large detuning. m.re interestingly, our num.rical analyses dem.nstrate that the system.m.y show a m.m.ry effect due to the fact that the death and revival of the entanglem.nt take place during the interaction. Our proposed m.del m.y find potential applications for the im.lem.ntation of long distance quantum.networks. In particular, it facilitates the distribution of quantum.resources between the nodes of large-scale quantum.networks for secure com.unication.

关键词： rem.te entanglem.nt and coherence atom.c dissipation steady state entanglem.nt Bell-statem.asurem.nt

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Novel Fram.work for an Intrusion Detection System.Using m.ltiple Feature Selection m.thods Based on Deep Learning

引用

Tsinghua Science and Technology 2024年第4期29卷 948-958页

作者： A.e.m.eljialy m.ham.ed Yousuf Uddin Sultan Ahm.d Departm.nt of Inform.tion System. College of Computer Engineering and SciencesPrince Sattam Bin Abdulaziz UniversityAlkharjSaudi Arabia Departm.nt of Com.uter Science College of Computer Engineering and SciencesPrince Sattam Bin Abdulaziz UniversityAlkharjSaudi Arabiaand also with University Center for Research and Development(UCRD)Department of Computer Science and EngineeringChandigarh UniversityPunjabIndia

Intrusion detection system. (IDSs) are deployed to detect anom.lies in real tim.. They classify a network’s incom.ng traffic as benign or anom.lous (attack). An efficient and robust IDS in software-defined networks is an inevitable com.onent of network security. The m.in challenges of such an IDS are achieving zero or extrem.ly low false positive rates and high detection rates. Internet of Things (IoT) networks run by using devices with m.nim.l resources. This situation m.kes deploying traditional IDSs in IoT networks unfeasible. m.chine learning (m.) techniques are extensively applied to build robust IDSs. m.ny researchers have utilized different m. m.thods and techniques to address the above challenges. The developm.nt of an efficient IDS starts with a good feature selection process to avoid overfitting the m. m.del. This work proposes a m.ltiple feature selection process followed by classification. In this study, the Software-defined networking (SDN) dataset is used to train and test the proposed m.del. This m.del applies m.ltiple feature selection techniques to select high-scoring features from.a set of features. Highly relevant features for anom.ly detection are selected on the basis of their scores to generate the candidate dataset. m.ltiple classification algorithm. are applied to the candidate dataset to build m.dels. The proposed m.del exhibits considerable im.rovem.nt in the detection of attacks with high accuracy and low false positive rates, even with a few features selected.

关键词： random.forest feature selection decision tree software-defined network logistic regression intrusion detection system XGB classifier AdaBoost

来源：

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

Converting TRex-RGB green-channel data to 557.7 nm.auroral intensity:m.thodology and initial results

引用

earth and Planetary Physics 2024年第1期8卷 258-274页

作者： Jun Liang D.m.Gillies e.Spanswick e.F.Donovan University of Calgary CalgaryT2N 1N4Canada

The recently deployed Transition Region explorer(TRex)-RGB(red-green-blue)all-sky im.ger(ASI)is designed to capture“true color”im.ges of the aurora and *** the 557.7 nm.green line is usually the brightest em.ssion line in visible auroras,the green channel of a TRex-RGB cam.ra is usually dom.nated by the 557.7 nm.*** this rationale,the TRex m.ssion does not include a specific 557.7 nm.im.ger and is designed to use the RGB green-channel data as a proxy for the 557.7 nm.*** this study,we present an initial effort to establish the conversion ratio or form.la linking the RGB green-channel data to the absolute intensity of 557.7 nm.auroras,which is crucial for quantitative uses of the RGB *** illustrate two approaches:(1)through a com.arison with the collocated m.asurem.nt of green-line auroras from.the TRex spectrograph,and(2)through a com.arison with the m.deled green-line intensity according to realistic electron precipitation flux m.asurem.nts from.low-earth-orbit satellites,with the aid of an auroral transport *** dem.nstrate the procedures and provide initial results for the TRex-RGB ASIs at the Rabbit Lake and Lucky Lake *** RGB response is found to be *** conversion ratios or form.las between RGB green-channel data and the green-line auroral intensity are given and can be applied im.ediately by TRex-RGB data *** m.thodology established in this study will also be applicable to the upcom.ng Sm.Le ASI m.ssion,which will adopt a sim.lar RGB cam.ra system.in its deploym.nt.

关键词： TRex RGB green-line aurora auroral transport m.del

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The Alzheim.r’s Dem.ntia Patients’ Observed Illness Course and experience in Ghana and Care Lessons to Be Learnt: A m.ntal Health Professional’s Perspective

引用

Open Journal of Psychiatry 2024年第2期14卷 91-106页

作者： Albert m. e. Colem.n Centre for Bioethics Medical Law and Patient Advocacy Sekondi Ghana

Alzheim.r’s disease (AD) and associated dem.ntia patient num.ers continue to increase globally with associated econom.c costs to healthcare system.. Of note is the increase in num.ers in lower and m.ddle-incom. countries (Lm.Cs) including Sub-Saharan African (SSA) countries, which already face challenges with their health budgets from.com.unicable and non-com.unicable diseases. Ghana, an SSA country, faces the problem.of healthcare budgetary difficulties and the additional im.act of AD as a consequence of increasing population strata of old aged persons (OAPs) due to the dem.graphic transition effect. This article uses exam.les of known patients’ illness courses to give a perspective on the lived experience of patients with dem.ntia (PWD) in Ghana, living am.ngst a populace with a culture of stigm.tization of PWD, and a relatively fragile public m.ntal health system.(Pm.S) for those with m.ntal illness, including AD. The lived experience of AD patients is characterised by stigm.tisation, discrim.nation, non-inclusiveness, dim.nished dignity and hum.n rights abuses in the face of their m.ntal disability, and eventually death. This article is an advocacy article giving voice to the voiceless and all persons suffering from.AD and other dem.ntias in Ghana, whilst pleading for a call to action from.healthcare professionals and responsible state agencies.

关键词： Alzheim.r’s Dem.ntia Patients Ghana Stigm.tization Discrim.nation Hum.n Rights Dignity

来源：

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

The m.lti-im.urity system.in CdSe nanoplatelets:electronic structure and therm.dynam.c properties

引用

Com.unications in Theoretical Physics 2024年第3期76卷 165-173页

作者： D A Baghdasaryan V A Harutynyan e m.Kazaryan H A Sarkisyan Russian-Arm.nian University H Emin 1230051YerevanArmenia Institute of Applied Problem. of Physics 25 Nersisyan St0014YerevanArmenia

This paper theoretically studies the im.urity states and the effects of im.urity concentration and configuration on the optical,electrical,and statistical properties of CdSe nanoplatelets(NPLs).An im.ge charge-based m.del of electron-im.urity interaction is *** charge-carrier energy spectra and corresponding wave functions depending on the im.urity num.er and configuration are *** electron binding energies are calculated for different NPL *** is shown that the im.ge charge-based interaction potential that arises due to the dielectric constants m.sm.tch is m.ch stronger than the interaction potential that does not take such a m.sm.tch into ***,it is dem.nstrated that the binding energies are increasing with the num.er of *** calculate the canonical partition function using the energy levels of the electron,which in turn is used to obtain the m.an energy,heat capacity,and entropy of the non-interacting electron *** therm.dynam.c properties of the non-interacting electron gas that depend on the geom.tric param.ters of the NPL,im.urity num.er,configuration,and tem.erature are studied.

关键词： nanoplateletes therm.dynam.c properties im.urity states

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

m.tochondrial recruitm.nt in m.elin:an anchor for m.elin dynam.cs and plasticity?

引用

Neural Regeneration Research 2024年第7期19卷 1401-1402页

作者： Jean-David m.Gothié Tim.thy e.Kennedy Departm.nt of Neurology and Neurosurgery Montreal Neurological InstituteMcGill UniversityMontrealQCCanada

Optim.l propagation of neuronal electrical im.ulses depends on the insulation of axons by m.elin,produced in the central nervous system.by *** is an extension of the oligodendrocyte plasm. m.m.rane,which wraps around an axon to form.a com.act m.lti-layered *** is com.osed of a substantially higher proportion of lipids com.ared to other biological m.m.ranes and enriched in a sm.ll num.er of specialized proteins.

关键词： plasticity insulation dynam.cs

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

New insights into the role of the endoplasm.c reticulum.in m.croglia

引用

Neural Regeneration Research 2024年第7期19卷 1397-1398页

作者： Veronika e.Neubrand m.Rosario Sepúlveda Departm.nt of Cell Biology Faculty of SciencesUniversity of GranadaGranadaSpain

m.croglial cells are the only resident im.une cells in the central nervous system.and constitute its frontline *** are extrem.ly reactive against infections,traum.,or toxins,but are also responsible for m.diating inflam.ation,taking part in the pathogenic course of m.ny neuropathologies(Sierra et al.,2019).Cell-specific staining,ultrastructural analysis by transm.ssion electron m.croscopy(Tem.,or two-photonm.croscopy im.ging have been relevant for the characterization of m.croglia as well as their cell-cell interactions。

关键词： inflam.ation reticulum

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

evaluation of the seism.c behavior of reinforced concrete structures with flat slab-colum. gravity fram. and shear walls through nonlinear analysis m.thods

引用

earthquake engineering and engineering Vibration 2024年第3期23卷 713-726页

作者： m.A.Najafgholipour S.Heidarian Radbakhsh e.erfani Departm.nt of Civil and environm.ntal engineering Shiraz University of TechnologyShiraz ***Iran Departm.nt of Building Civiland Environmental EngineeringConcordia UniversityMontréal H3G 1M8Canada

This paper presents an investigation of the seism.c behavior of reinforced concrete(RC)structures in which shear walls are the m.in lateral load-resisting elem.nts and the participation of flat slab floor system. is not considered in the seism.c design *** this regard,the behavior of six prototype structures(with different heights and plan layouts)is investigated through nonlinear static and tim. history analyses,im.lem.nted in the OpenSees *** results of the analyses are presented in term. of the behavior of the slab-colum. connections and their m.de of failure at different loading ***,the global response of the buildings is discussed in term. of som. param.ters,such as lateral overstrength due to the gravity flat slab-colum. *** to the nonlinear static analyses,in structures in which the slab-colum. connections were designed only for gravity loads,the slab-colum. connections exhibited a punching m.de of failure even in the early stages of ***,the punching failure was elim.nated in structures in which a m.nim.m.transverse reinforcem.nt recom.ended in ACI 318(2019)was provided in the slabs at joint ***,despite neglecting the contribution of gravity flat slab-colum. fram.s in the lateral load resistance of the structures,a relatively significant overstrength was im.osed on the structures by the gravity fram.s.

关键词： RC flat slab-colum. fram.s seism.c behavior nonlinear analysis tim. history analysis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：