检索结果-南通市图书馆

High Voltage Direct Current (HVDC) Transmission: Future Expectation for Pakistan

在线全文

学校读者我要写书评

暂无评论

CSEE Journal of Power and Energy Systems 2019年第1期5卷 82-86页

作者： Kamran Hafeez shahid A.khan Electrical Engineering Department CIIT Islamabad campus Pakistan

An HVDC transmission system for bulk power transfer over longer distance offers numerous advantages over an alternating current(AC)transmission system,such as direct integration of networks operating at different frequencies,comparatively low line losses on account of constant current and absence of *** paper presents details about HVDC power transmission systems and power converter *** concerning integration of electrical power generated by alternate sources(i.e.,wind,onshore and offshore)into the national grid of Pakistan using HVDC technology are also *** studies revealed that the energy crisis of countries like Pakistan can be mitigated to a larger extent with the use of HVDC transmission systems.

关键词： HVDC renewable energy transmission systems wind Energy

A Survey of VASNET Framework to Provide Infrastructure-Less Green IoTs Communications for Data Dissemination in Search and Rescue Operations

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 Electronic Science and Technology 2016年第3期14卷 220-228页

作者： Mohamad Nazim Jambli Adnan shahid khan Sia Chiu Shoon the Faculty of Computer Science and Information Technology Universiti Malaysia Sarawak94300 Kota SamarahanMalaysia

implementation of wireless technologies based on the vehicular ad hoc sensor network （VASNET） may provide support for the search and rescue （SAR） team to operate effectively in natural disaster events, such as landslide, earthquake, flooding, and tsunami. The operations of SAR team are very challenging in such events due to the possible damages of the existing telecommunication infrastructures. The existing deployment of the cellular communications infrastructure may be partially or completely destroyed after the occurrence of these natural disasters. Thus, the current VASNET infrastructure must be able to support the infrastructure-less network by integrating other green wireless technologies that can benefit the SAR team, which can indirectly save more human lives and reduce the number of casualties. Therefore, the integration of green Internet of things （loT） and VASNET is proposed to form a heterogeneous framework for data dissemination in SAR operations. In addition, this paper also discusses the existing lot framework in disaster scenarios with future research direction for IoT using on any aspect, especially related to the natural disaster scenarios.

关键词： Framework green Internet of things (loT) SAR operations vehicular ad hoc sensor network (VASNET).

Regio-and enantioselective formation of tetrazole-bearing quaternary stereocenters via palladium-catalyzed allylic amination

在线全文

学校读者我要写书评

暂无评论

Organic Chemistry Frontiers 2022年第2期9卷 456-461页

作者： shahid khan Yu Wang Mei-Na Zhang shahida Perveen Junjie Zhang Ajmal khan Department of Chemistry School of ChemistryXi’an Key Laboratory of Sustainable Energy Materials Chemistry and MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed MatterXi’an Jiao Tong UniversityXi’an 710049P.R.China

Based on palladium-catalyzed allylic amination reaction,the first general example of enantioselective formation of a tetrazole-bearing quaternary stereocenter has been *** protocol uses ambivalent tetrazole and vinyl cyclic carbonates as easily available coupling *** operationally simple methodology is further characterized by its wide substrate scope,high enantioselectivity and excellent branched to linear regioselectivity,thus unlocking a new platform that permits the synthesis of elusive quaternary N2-allylic tetrazoles,even in the context of late-stage functionalization.

关键词： quaternary palladium catalyzed

Development of mutants with varying flowering times by targeted editing of multiple SVP gene copies in Brassica napus L.

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 Crop Journal 2022年第1期10卷 67-74页

作者： Sunny Ahmar Yungu Zhai Huibin Huang Kaidi Yu Muhammad Hafeez Ullah khan Muhammad shahid Rana Abdul Samad shahid Ullah khan Olalekan Amoo Chuchuan Fan Yongming Zhou National Key Laboratory of Crop Genetic Improvement Huazhong Agricultural UniversityWuhan 430070HubeiChina

Manipulation of flowering time to develop cultivars with desired maturity dates is fundamental in plant *** is desirable to generate polyploid rapeseed(Brassica napus L.)germplasm with varying flowering time controlled by a few *** the present study,Bna SVP,a rapeseed homolog of the Arabidopsis SVP(Short Vegetative Phase)gene,was characterized and a set of mutants was developed using a CRISPR/Cas9-based gene-editing tool.A single construct targeting multiple sites was successfully applied to precisely mutate four copies of Bna *** induced mutations in these copies were stably transmitted to subsequent *** mutants with loss-of-function alleles and free transgenic elements were generated across the four Bna SVP *** mutant T_(1)lines tested in two environments(summer and winter growing seasons)showed early-flowering *** decrease in flowering time was correlated with the number of mutated Bna SVP *** quadruple mutants showed the shortest flowering time,with a mean decrease of 40.6%–50.7%in length relative to the wild type under the two growth *** study demonstrates the quantitative involvement of Bna SVP copies in the regulation of flowering time and provides valuable resources for rapeseed breeding.

关键词： Brassica napus Flowering time BnaSVP Gene editing

A Compact Rhombus Shaped Antenna with Extended Stubs for Ultra-Wideband Applications

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2022年第11期73卷 2637-2650页

作者： Syed Misbah un Noor Muhammad Amir khan shahid khan NZ Jhanjhi Mamoona Humayun Hesham A.Alhumyan Department of Electrical Engineering IIC University of TechnologyPhnom PenhCambodia Department of Computer Science COMSATS University IslamabadAbbottabad Campus22060Pakistan Department of Electrical and Computer Engineering COMSATS University IslamabadAbbottabad Campus22060Pakistan School of Computer Science SCSTaylor’s UniversitySubang Jaya47500SelangorMalaysia 5Center for Smart Society 0 CSS5 Faculty of Innovation and TechnologyTaylor’s UniversitySubang Jaya47500Malaysia Department of Information Systems College of Computer and Information SciencesJouf UniversityAl-JoufKSA

Ultra-wideband(UWB)is highly preferred for short distance *** a result of this significance,this project targets the design of a compact UWB *** paper describes a printed UWB rhombusshaped antenna with a partial ground *** achieve wideband response,two stubs and a notch are incorporated at both sides of the rhombus design and ground plane *** excite the antenna,a simple microstrip feed line is *** suggested antenna is built on a 1.6 mm thick FR4 *** proposed design is very compact with overall electrical size of 0.18λ×0.25λ(14×18 mm2).The rhombus shaped antenna covers frequency ranging from 3.5 to 11 GHz with 7.5 GHz impedance *** proposed design simulated and measured bandwidths are 83.33%and 80%,*** pattern in terms of E-field and H-field are discussed at 4,5.5 and 10 GHz *** proposed design has 65%radiation efficiency and 1.5 dBi peak *** proposed design is simulated in CST(Computer Simulation Technology)simulator and the simulated design is fabricated for the measured *** simulated and measured findings are in close *** obtained results confirm the application of the proposed design for the ultra-wide band applications.

关键词： Ultra-wideband impedance bandwidth radiation pattern CST electrical size

Reconfigurable Compact Wideband Circularly Polarised Dielectric Resonator Antenna for Wireless Applications

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2021年第8期68卷 2095-2109页

作者： shahid khan Xin Cheng Ren Haider Ali Camel Tanougast Abdul Rauf Safdar Nawaz khan Marwat Muhammad Rizwan Anjum LCOMS ASECUniversity de LorraineMetz57070France School of Physics and Electronic Information Yanan UniveristyYanan761000China Department of Electronics Technology University of TechnologyNowshera24100Pakistan Department of Electrical Engineering National University of Sciences and TechnologyIslamabad44000Pakistan Department of Computer Systems Engineering University of Engineering and TechnologyPeshawar25120Pakistan Department of Electronic Engineering The Islamia University of BahawalpurBahawalpur63100Pakistan

In this work,a novel compact wideband reconfigurable circularly polarised(CP)dielectric resonator antenna(DRA)is *** L-shaped Dielectric resonator antenna is excited by an inverted question mark shaped *** arrangement of feed-line helps to generate two orthogonal modes inside the DR,which makes the design circularly polarised.A thin micro-strip line placed on the defected ground plane not only helps to generate a wideband response but also assist in the positioning of the two diode *** switches located at the left and right of the micro-strip line helps in performing two switching *** novel compact design offers the reconfigurability between 2.9–3.8 GHz which can be used for different important wireless *** the switching operation I,the achieved impedance bandwidth is 24%while axial ratio bandwidth(ARBW)is 42%.For this switching state,the design has 100%CP ***,the switching operation II achieves 60%impedance bandwidth and 58.88%ARBW with 76.36%CP *** proposed design has a maximum measured gain of 3.4 dBi and 93%radiation *** proposed design is novel in terms of compactness and performance *** prototype is fabricated for the performance analysis which shows that the simulated and measured results are in close agreement.

关键词： Circularly polarized DRA ARBW bandwidth gain radiation efficiency

Halogen-based functionalized chemistry engineering for high-performance supercapacitors

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 Chemical Letters 2023年第1期34卷 114-126页

作者： Wuquan Ye Hongfei Wang Junling Shen shahid khan Yijun Zhong Jiqiang Ning Yong Hu Key Laboratory of the Ministry of Education for Advanced Catalysis Materials Department of ChemistryZhejiang Normal UniversityJinhua 321004China Department of Optical Science and Engineering Fudan UniversityShanghai 200438China Hangzhou Institute of Advanced Studies Zhejiang Normal UniversityHangzhou 311231China

Supercapacitors(SCs)are rated as the foremost efficient devices bridging the production and consumption of renewable *** address the ever-increasing energy requirements,it is indispensable to further develop high-performance SCs with merits of high energy-density,acceptable price and long-term *** review highlights the recent advances on halogen-based functionalized chemistry engineering in the state-of-the-art electrode system for high-performance SCs,primarily referring to the doping and decoration strategies of F,Cl,Br and I *** to the discrepancy of electronegativity and atomic radius,the functionalization of each halogen element endows the substrate materials with different physicochemical properties,including energy bandgap structure,porosity distribution and surface *** principle of halogen embedment into host materials by precisely controlling ionic adsorption and electronic structure is ***,the vital perspectives on the future challenges of halogen functionalization are also *** work aims to deepen the understanding of halogen-based functionalized strategies to motivate further research for the development of high-performance SCs,and it also provides a prospect for exploring new material modification methods for electrochemical energy storage.

关键词： Halogen-based functionalized chemistry Doping strategy Decoration strategy Electrode materials Supercapacitors

Comparison of the reaction of polar mesosphere winter echoes and polar mesosphere summer echoes to high-frequency heating in terms of modulated characteristics

在线全文

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2023年第2期7卷 247-256页

作者： Safi Ullah HaiLong Li Abdur Rauf shahid Ullah khan Sufyan Ullah khan ShuCan Ge Bin Wang MaoYan Wang Lin Meng School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu 610054China Department of Physics Riphah International University Islamabad CampusIslamabad 45210Pakistan Department of Physics University of Science and Technology BannuBannu 28101Pakistan National Key Laboratory of Electromagnetic Environment China Research Institute of Radiowave PropagationQingdao 266107China School of Physics University of Electronic Science and Technology of ChinaChengdu 610054China

In this work,for the first time,we have analyzed and compared the responses of polar mesosphere winter echoes(PMWE)and their summer counterpart,polar mesosphere summer echoes(PMSE),to high-frequency(HF)heating in terms of modulated characteristics(i.e.,backscatter intensity reduction,recovery,and overshoot).Both PMWE and PMSE observations were from the same site(Tromsφ,Norway;69.6°N,19.2°E)and radar(EISCAT[European Incoherent Scatter Scientific Association]very high frequency,224 MHz).The heating patterns of both PMWE and PMSE were found to be similar;however,PMSE was more greatly affected by HF *** mesosphere summer echoes showed recovery and overshoot more frequently than did *** addition,the mean recovery and overshoot of PMSE were greater than those of *** associated electron temperature enhancement was estimated for both PMWE and PMSE and showed that,compared with PMWE,the electron temperature enhancement was more significant in *** strong heating effects on PMSE may be due to the considerable increase in electron temperature.

关键词： polar mesosphere winter echo polar mesosphere summer echo electromagnetic wave heating experiment dusty plasma ionosphere

Hepatocellular carcinoma: Epidemiology, risk factors and pathogenesis

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2008年第27期14卷 4300-4308页

作者： Asmaa Ibrahim Gomaa shahid a khan Mireille B Toledano Imam Waked Simon D Taylor- Robinson Department of Hepatology and Gastroenterology Imperial College London St Mary’s Hospital Campus Department of Epidemiology and Public Health Imperial College London St Mary’s Hospital Campus National Liver Institute Menoufiya University

Hepatocellular carcinoma (HCC) is the commonest primary malignant cancer of the liver in the world. Given that the burden of chronic liver disease is expected to rise owing to increasing rates of alcoholism, hepatitis B and C prevalence and obesity-related fatty liver disease, it is expected that the incidence of HCC will also increase in the foreseeable future. This article summarizes the international epidemiology, the risk factors and the pathogenesis of HCC, including the roles of viral hepatitis, toxins, such as alcohol and aflatoxin, and insulin resistance.

关键词： Hepatocellular carcinoma Epidemiology Risk factors Aetiology Pathogenesis