检索结果-南通市图书馆

Does black hole spin play a key role in the FSRQ/BL Lac dichotomy?

Research in Astronomy and Astrophysics 2016年第4期16卷 7-14页

作者： Debbijoy bhattacharya Parameswaran Sreekumar Banibrata Mukhopadhyay Ishan Tomar Manipal Centre for Natural Sciences Manipal UniversityManipal 576104India Indian Institute of Astrophysics Bangalore 560034India Astronomy and Astrophysics Programme Department of PhysicsIndian Institute of ScienceBangalore 560012India Space Astronomy Group ISRO Satellite CentreKarthik NagarBangalore 560037India

Blazars are characterized by large intensity and spectral variations across the electromagnetic spectrum It is believed that jets emerging from them are almost aligned with the line-of-sight. The major- ity of identified extragalactic sources in γ-ray catalogs of EGRET and Fermi are blazars. Observationally, blazars can be divided into two classes： fiat spectrum radio quasars （FSRQs） and BL Lacs. BL Lacs usually exhibit lower γ-ray luminosity and harder power law spectra at γ-ray energies than FSRQs. We attempt to explain the high energy properties of FSRQs and BL Lacs from Fermi γ-ray space telescope observations. It was argued previously that the difference in accretion rates is mainly responsible for the large mismatch in observed luminosity in ＂7-ray. However, when intrinsic luminosities are derived by correcting for beaming effects, this difference in 7-ray luminosity between the two classes is significantly reduced. In order to ex- plain this difference in intrinsic luminosities, we propose that spin plays an important role in the luminosity distribution dichotomy of BL Lacs and FSRQs. As the outflow power of a blazar increases with increasing spin of a central black hole, we suggest that the spin plays a crucial role in making BL Lac sources low luminous and slow rotators compared to FSRQ sources.

关键词： BL Lacertae objects: general -- quasars: general -- galaxies: jets -- black hole physics --relativistic processes -- gravitation

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 Chance-Constrained Wind Range Quantification Approach to Robust SCUC by Determining Dynamic Uncertainty Intervals

引用

CSEE Journal of Power and Energy Systems 2016年第1期2卷 54-64页

作者： aditi Upadhyay Bingqian Hu Jie Li Lei Wu ECE Department Clarkson UniversityPotsdamNYUSA

With increasing penetration of wind energy,the variability and uncertainty of wind resources have become important factors for power systems *** particular,an effective method is required for identifying the stochastic range of wind power output,in order to better guide the operational security of power *** paper proposes a metric to determine accurate wind power output ranges so that the probability of actual wind power outputs being out of the range would be less than a small pre-defined value.A mixed-integer linear programming(MILP)based chance-constrained optimization model is proposed for efficiently determining optimal wind power output ranges,which are quantified via maximum and the minimum wind generation levels with respect to a certain time *** derived wind power range is then used to construct dynamic uncertainty intervals for the robust securityconstrained unit commitment(SCUC)model.A comparison with the deterministic SCUC model and the traditional robust SCUC model with presumed static uncertainty interval demonstrates that the proposed approach can offer more accurate wind power variabilities(i.e.,different variability degrees with respect to different wind power output levels at different time periods).The proposed approach is also shown to offer more effective and robust SCUC solutions,guaranteeing operational security and economics of power *** case studies on a 6-bus system and the modified IEEE 118-bus system with realworld wind power data illustrate the effectiveness of the proposed approach.

关键词： Chance-constrained optimization MILP renewable energy integration SCUC wind power ranges

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

Gamma-ray luminosity function of gamma-ray bright AGNs

引用

Chinese Journal of Astronomy and Astrophysics 2009年第1期9卷 85-94页

作者： Debbijoy bhattacharya P.Sreekumar R.Mukherjee Department of Physics Indian Institute of Science Space Astronomy & Instrumentation Division ISRO Satellite Centre Barnard College Columbia University

Detection of γ-ray emissions from a class of active galactic nuclei （viz blazars）, has been one of the important findings from the Compton Gamma-Ray Observatory （CGRO）. However, their γ-ray luminosity function has not been well determined. Few attempts have been made in earlier works, where BL Lacs and Flat Spectrum Radio Quasars （FSRQs） have been considered as a single source class. In this paper, we investigated the evolution and γ-ray luminosity function of FSRQs and BL Lacs separately. Our investigation indicates no evolution for BL Lacs, however FSRQs show significant evolution. Pure luminosity evolution is assumed for FSRQs and exponential and power law evolution models are examined. Due to the small number of sources, the low luminosity end index of the luminosity function for FSRQs is constrained with an upper limit. BL Lac luminosity function shows no signature of break. As a consistency check, the model source distributions derived from these luminosity functions show no significant departure from the observed source distributions.

关键词： galaxies active -- galaxies evolution -- galaxies luminosity function -- gamma-rays observations

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 New Classification of Path-Delay Fault Testability in Terms of Stuck-at Faults

引用

Journal of Computer Science & Technology 2004年第6期19卷 955-964页

作者： SubhashisMajumder BhargabB.bhattacharya VishwaniD.Agrawal MichaelL.Bushnell InternationalInstituteofInformationTechnology Kolkata700091India ACMUnit IndianStatisticalInstituteKolkata700108India DepartmentofECE AuburnUniversityAlabamaAL36849U.S.A. DepartmentofECE RutgersUniversityPiscatawayNJ08855U.S.A.

A new classification of path-delay fault testability in a combinational circuit is presented in terms of testability of stuck-at faults in an equivalent circuit. Earlier results describing correlation of path-delay and stuck-at faults are either incomplete, or use a complex model of equivalent circuit based on timing parameters. It is shown here that a path-delay fault (rising or falling) is testable if and only if certain single or multiple stuck-at fault in the equivalent circuit is testable. Thus, all aspects of path-delay faults related to testability under various classification schemes can be interpreted using the stuck-at fault model alone. The results unify most of the existing concepts and provide a better understanding of path-delay faults in logic circuits. Keywords delay fault - false path - redundancy - stuck-at fault Regular PaperThis work was funded in part by Motorola India Electronics Ltd., Bangalore 560042, India.An earlier version of this paper appeared in the Proceedings of the 12th Int. Coaf. VLSI Design, Jan. 1999.Subhashis Majumder is a professor and course leader for the Computer Science and Engineering Department of International Institute of Information Technology, Kolkata. He started his career in Texas Instruments India Pvt. Ltd. and has over seven years of industry experience. He received his M. Tech degree in computer science from the Indian Statistical Institute, Kolkata in 1996. His undergraduate work was done in the Electronics and Telecommunication Engineering Dept. of the Jadvpur University, Koikata. He also worked as a research assistant in the Computer Eng. Dept. of Rutgers University for a year. He has led product development teams working on protocol stack development as well as VoIP. His current areas of interest include delay fault testing, wire routing, partitioning, approximation algorithms, and application of computational geometry to CAD problems.Bhargab B. bhattacharya received the ***. degree in physics fr

关键词： delay fault false path redundancy stuck-at fault

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

Antifertility potential of leaves and seeds of Delonix regia in female rats

引用

Asian pacific Journal of Reproduction 2023年第3期12卷 117-123,I0001,I0002页

作者： Garg Megha Sharma aditi Choudhary Manjusha Kaur Prabhjeet Institute of Pharmaceutical Sciences Kurukshetra UniversityKurukshetraIndia

Objective:To evaluate the antifertility activity of hydroalcoholic extract of Delonix regia(*** Hook.)*** and seeds which are traditionally being used by Yanadi tribe to treat ***:Three experimental animal models,including anti-implantation,early abortifacient,and estrogenic activity in female rats,were used for evaluation of the antifertility activity of both extracts at two dose levels(250 and 500 mg/kg,orally).There were five groups in the anti-implantation and early abortifacient activity while six groups in estrogenic activity including the *** number of implants,resorptions,vaginal cornification,body weight,uterus weight,and biochemical parameters were ***:At doses 250 and 500 mg/kg,the leaf extract was found to have strong anti-implantation *** extract administered at the same doses also caused a significant rise in the number of resorptions,showing early abortifacient activity,increased uterine weight,and altered numerous biochemical ***,the seed extract only displayed slight anti-implantation activity at both ***:Based on these preliminary findings,we can conclude that the leaf extract outperformed the seed extract in terms of antifertility activity,exhibiting potent estrogenic,anti-implantation and early abortifacient activities in a dose-dependent *** findings are consistent with the literature study and corroborate to the antifertility activity of the plant.

关键词： Delonix regia Anti-implantation Early abortifacient Estrogenic Gulmohar Ovariectomy

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 backward bifurcation of a model for malaria infection

引用

International Journal of Biomathematics 2018年第2期11卷 65-82页

作者： Juan Wang Xue-Zhi Li Souvik bhattacharya Department of Mathematics Zhengzhou University Zhengzhou 450000 P. R. China Department of Mathematics Xinyang Normal University Xinyang 464000 P. R. China College of Mathematics and Physics Anyang Institute of Technology Anyang 455000 P. R. China Department of Mathematics University of Florida Gainesville FL 32611-8105 USA

In this paper, an epidemic model of a vector-borne disease, namely, malaria, is consi- dered. The explicit expression of the basic reproduction number is obtained, the local and global asymptotical stability of the disease-free equilibrium is proved under certain conditions. It is shown that the model exhibits the phenomenon of backward bifurcation where the stable disease-free equilibrium coexists with a stable endemic equilibrium. Further, it is proved that the unique endemic equilibrium is globally asymptotically stable under certain conditions.

关键词： Host-vector disease model basic reproduction number equilibrium backwardbifurcation global stability.

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

Influence of welding parameters on material flow,mechanical property and intermetallic characterization of friction stir welded AA6063 to HCP copper dissimilar butt joint without offset

引用

Transactions of Nonferrous Metals Society of China 2015年第9期25卷 2833-2846页

作者： T.K.bhattacharya H.DAS T.K.PAL Welding Technology Centre Metallurgical and Material Engineering DepartmentJadavpur University

Joining of dissimilar aluminium-copper is an emerging area of interest for both research and industry due to its complex *** stir welding was attempted to evaluate the joint strength without offset at the butt line between AA6063 to HCP copper sheet under different combination of rotational speed of 800 and 1000 r/min and travel speed of 20 and 40 mm/*** flow was studied in detail for different combinations of parameters with optical microscopy and elemental mapping by energy dispersive X-ray spectroscopy（EDS）.The results were correlated with the microstructural characteristics and formation of intermetallics at the bond interface using microhardness test and X-ray diffraction（XRD） *** flow clearly suggests that energy input at 800 r/min and 20 mm/min is sufficient to plasticize both the materials with formation of higher amount of thermodynamically stable and hard intermetallic phases Al4Cu9 and Al Cu4（slower cooling rate of 88 K/s） than that at 800 r/min and 40 mm/min（faster cooling rate of 154 K/s）,attributed maximum joint strength（~78.6% of aluminium base metal）.

关键词： friction stir welding(FSW) AA6063 alloy HCP copper material flow

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

Performance characterization of Bi_2O_3/Al nanoenergetics blasted micro-forming system

引用

Defence Technology（防务技术） 2019年第1期15卷 98-105页

作者： Vinay Kumar Patel Rishi Kant Anu choudhary Madhusudan Painuly Shantanu bhattacharya Department of Mechanical Engineering Govind Ballabh Pant Institute of Engineering & Technology Pauri-Garhwal Department of Mechanical Engineering Indian Institute of Technology Kanpur

This paper reports a novel micro-blast driven manufacturing process for micro-forming of Aluminum foils. The micro-blast is realized by using a nanoenergetic material system comprising of Bi_2O_3 microrods and aluminum particles. There is an enhanced need of forming of thin aluminum foil structures in small regions from point of view of drug packaging etc. The process developed caters to this need by using a single shot forming process using a micro-blast source. The micro-blast that is generated from an energetic composite system is made highly tunable by modulating the peak pressure generated through the blasting process and their impact in micro-forming of thin aluminum foils is observed through parametric studies. The engineering challenge involved in these experiments is to tune the blast pressure properties in order to address the forming of thin metal sheets with limiting boundary values as defined by the failure criteria. A variety of characterization techniques related to a thorough analysis of the synthesized material viz. X-ray diffraction(XRD), Scanning Electron Microscopy(SEM) etc, are used to tune the functional properties like gauge blast pressure etc, of material system. We have found a material system that can generate a maximum peak pressure of 73.8 MPa with pressurization rate of 2460 GPas^(-1) and that is able to accomplish micro-forming on thin metal foils(around 0.3 mm thickness). Experimental investigations demonstrate that tunabilty aspect of the energetic composites when exercised can enable variant processes such as embossing, coining, drilling etc. which may be of significant utility to drug packaging industries. A proper mathematical modeling of the forming process and critical process parameters therein have also been detailed.

关键词： Microforming Aluminum Foil Bi2O3 Nanoenergetic Tunability Process parameters

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

Effect of weathering on physico-chemical properties and combustion behavior of an Indian thermal coal

引用

International Journal of Coal Science & Technology 2019年第1期6卷 51-62页

作者： Subhajit Aich Barun Kumar Nandi Sumantra bhattacharya Department of Fuel and Mineral Engineering Indian Institute of Technology (Indian School of Mines)Dhanbad Dhanbad Jharkhand 826004India

An open air stockpile of conical shape was formed with 3.5 m base diameter and 5 m height using 500 tons of -200 mm size ROM thermal coal on a concrete floor. Coal sample from the stockpile were collected at 30 days interval for analysis of various chemical properties like;proximate analysis, ultimate analysis, gross calorific value (GCV) and various combustion related properties such as ignition temperature, peak temperature, burnout temperature, maximum combustion rate, ignition index, burnout index, combustion performance index and combustion rate intensity index. Experimental results show that, due to weathering of coal fixed carbon decreased from 35.6% to 19.9%, elemental carb on (C) decreased from 46.6% to 28.6%, hydrogen (H) decreased from 3.3% to 2.9% and GCV decreased by up to 55% of original value during 330 days of storage of coal in an open atmosphere. Ash con tent of coal increased form 29.2% to 46.6% due to loss of combustibles. Sulfur (S) of coal was found to get increased from 0.33% to 1.08% during storage. The activation energy of coal combustion increased from 22 kJ/mol to 54 kJ/mol. Variation in combustion parameters signifies that weathering has significant negative impact on coal combustion properties as coal become difficult to ignite.

关键词： Weathering of coal TGA-DTG Combustibles Coal combustion Activation energy

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

Dedifferentiated liposarcoma arising from the sigmoid mesocolon: A case report

引用

World Journal of Gastroenterology 2007年第30期13卷 4147-4148页

作者： Brody Winn John Gao Homayoon Akbari Baishali bhattacharya Department of Pathology and Surgery Rhode Island Hospital Warren Alpert Medical School of Brown University Providence Rhode Island United States Department of Surgery Rhode Island Hospital Warren Alpert Medical School of Brown University Providence Rhode Island United States

Dedifferentiated liposarcoma is a variant of liposarcoma with a more aggressive course. It occurs most commonly in the retroperitoneum and rarely in other anatomic locations. In the present report, we describe a case of dedifferentiated liposarcoma that occurred in an unusual location, sigmoid mesocolon, which has not yet been documented.

关键词： Dedifferentiated liposarcoma Sigmoid mesocolon

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

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：