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Electron-positron pair production in a strong asymmetric laser electric field

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Frontiers of physics 2014年第2期9卷 157-163,F0004页

作者： Obulkasim Oluk Bai-Song Xie muhmmad ali Bake SayipjamalDulat School of Physics Science and Technology Xinjiang University Urumqi 830046 China College of Nuclear Science and Technology Beijing Normal University Beijing 100875 China

By solving the quantum Vlasov equation, electron positron pair production in a strong electric field with asymmetric laser pulses has been investigated. We consider three different situations of subcycle, cycle and supercycle laser pulses. It is found that in asymmetric laser pulse field, i.e.. when the pulse length of one rising or falling side is fixed while the pulse length of the other side is changed, the pair production rate and mnnber density can be significantly modified comparable to symmetric situation. For each ca,se of these three different cycle pulses, when one side pulse length is constant and the other side pulse length becomes shorter, i.e., the whole pulse is compressed, the more pairs can be produced than that in tile vice versa case, i.e., the whole pulse is elongated. In compressed pulse case there exists an optimum pulse length ratio of asylnmetric pulse lengths which makes the pair number density maximunn. Moreover, the created maximum pair number density by subcycle pulse is larger than that by cycle or/and supercycle pulse. In elongated pulse case, however, only for supercycle laser pulse the created pairs is enhanced and there exists also an optimum asymmetric pulse length ratio that maximizes the pair number density. On the other hand. surprisingly, in both cases of subcycle and cycle elongated laser pulses, the pair number density is monotonically decreasing as the asymmetry of pulse increases.

关键词： electron-positron pair production quantum Vlasov equation (QVE) asymmetric laserelectric field

Elemental composition of rice using calibration free laser induced breakdown spectroscopy

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Optoelectronics Letters 2019年第1期15卷 57-63页

作者： Abdul Jabbar Mahmood Akhtar Arslan ali Shaukat Mehmood Sidra Iftikhar muhmmad Aslam Baig Department of Physics Mirpur University of Science and Technology National Centre for Physics

In this paper, we apply laser induce breakdown spectroscopy (LIBS) to determine the elemental composition of different parts(root, stem and seed) of the rice plant and determine their weighted concentration using calibration free laser induced breakdown spectroscopy (CF-LIBS) technique. Ca, Fe and K are identified as major elements, while C, Ti, Mg, Si, Li, Ba, Sr, Cr, Na and al as minor elements. We also detect the H-alpha line of hydrogen in the spectrum and determine the electron number density. The electron number density and its behavior as a function of laser energy, laser wavelength and the detector position are investigated. The plasma temperatures of samples are determined, and the validity of the assumption of the local thermodynamic equilibrium (LTE) is discussed.

关键词： Elemental composition calibration breakdown spectroscopy

Research on Layout of Recycling Places of Used Highway Asphalt Materials in Jiangsu Province and Analysis of Comprehensive Benefits

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Research on Layout of Recycling Places of Used Highway Aspha...

作者：哈什（muhmmad Hashim）东南大学

学位级别：硕士

After nearly 30 years of rapid development,the scale and capacity of China’s highway transportation network have been *** the same time,with the continuous extension of service life,a large number of trunk roads in China have entered the maintenance period,and the task of maintenance is becoming more and more *** to the statistics of the Ministry of transport,the annual waste asphalt mixture produced by the maintenance of trunk roads in China is nearly 200 million tons,and the recycling rate is less than 30%.Therefore,efficient recycling of waste materials in the process of pavement maintenance has important engineering economic and social environmental *** present,the single use of asphalt pavement recycling technology,whether it is recycling efficiency,recycling quality or recycling scale,will be difficult to meet the large-scale recycling demand of old materials in the future,which is also one of the important reasons for the low overall recycling rate of old materials in *** order to solve the above problems,this study focus on how to set up the asphalt material recycling yard of old highway in Jiangsu Province and analyze its comprehensive ***,this paper investigates and analyzes the health status and maintenance of expressways and trunk highways in Jiangsu Province,summarizes the engineering cases of the application of domestic recycling technology,and summarizes and analyzes the applicability of different recycling technologies based on the comparative analysis of the mechanism and process characteristics of different recycling ***,the output and demand of asphalt used materials of expressways and trunk highways are estimated,and the unified layout model of old material recovery points for collaborative recycling of old materials of expressways and ordinary trunk highways is determined in combination with the geographical environment analysis based on GIS and the comprehensive optimal transp

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Transcriptome Analysis and Physiological Responses of Economic Macroalga Gracilariopsis lemaneiformis under Sulfate Deficiency

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Phyton-International Journal of Experimental Botany 2023年第1期92卷 91-110页

作者： Haojie Jia Hong Du muhmmad Aslam Tangcheng Li Canqi Zheng Xihui Xie Nan Huang Honghao Liang Pengbing Pei Ping Li Weizhou Chen Xiaojuan Liu Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou) Guangzhou511458China Institute of Marine Sciences Guangdong Provincial Key Laboratory of Marine Biotechnology and STU-UNIVPM Joint Algal Research CenterCollege of SciencesShantou UniversityShantou515063China

Sulfur is an essential macronutrient for the growth of all photosynthetic organisms and plays important roles in different metabolic ***,sulfur metabolism and its related research on macroalgae with important ecological value is rather *** this study,marine ecological valued macroalga Gracilariopsis lemaneiformis was used to study the general physiological responses and transcriptome profiling under the sulfate *** relative growth rate of algae under sulfate deficiency was statistically significantly lower than that of control after 6 ***,no significant differences were observed in the pigments content and Fv/Fm value,indicating that the photosynthesis was not obviously affected under the sulfate ***,the significantly increased soluble protein and carbohydrate contents,and indistinctively differentially expressed sulfate transporter/permease(ST)and ATP sulfurylase(ATPS)genes suggesting that *** cells did not use sulfur from internal protein and carbohydrate pools but utilize stored sulfur from vacuole to satisfy their nutritional requirements during the sulfate *** data showed that most annotated differentially expressed genes(DEGs)were down-regulated under the sulfate deficiency,including a large proportion of genes involved in the pathway of sulfur ***,it was concluded that the pathway of sulfur metabolism was suppressed under the sulfate deficiency in *** results and analysis in this study provide a comprehensive understanding for the physiological and molecular response of *** to sulfate deficiency.

关键词： Gracilariopsis lemaneiformis sulfate deficiency sulfate sufficiency transcriptome

Recent Developments in Authentication Schemes Used in Machine-Type Communication Devices in Machine-to-Machine Communication: Issues and Challenges

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Computers, Materials & Continua 2024年第4期79卷 93-115页

作者： Shafi Ullah Sibghat Ullah Bazai Mohammad Imran Qazi Mudassar Ilyas Abid Mehmood Muhammad Asim Saleem muhmmad Aasim Rafique Arsalan Haider Ilyas Khan Sajid Iqbal Yonis Gulzar Kauser Hameed Department of Computer Engineering Balochistan University of Information TechnologyEngineering and Management SciencesQuetta87300Pakistan Department of Information Technology Balochistan University of Information TechnologyEngineeringand Management SciencesQuetta87300Pakistan Department of Information Systems College of Computer Sciences and Information TechnologyKing Faisal UniversityHofuf in Al-Ahsa31982Saudi Arabia Department of Management Information Systems College of Business AdministrationKing Faisal UniversityHofuf in Al-Ahsa31982Saudi Arabia Department of Software Engineering College of ComputingRiphah International UniversityFaisalabad44000Pakistan Department of Electrical Engineering Balochistan University of Information Technology Engineeringand Management SciencesQuetta87300Pakistan Department of Mathematics College of Science Al-ZulfiMajmaah UniversityAl-Majmaah11952Saudi Arabia

Machine-to-machine (M2M) communication plays a fundamental role in autonomous IoT (Internet of Things)-based infrastructure, a vital part of the fourth industrial revolution. Machine-type communication devices(MTCDs) regularly share extensive data without human intervention while making all types of decisions. Thesedecisions may involve controlling sensitive ventilation systems maintaining uniform temperature, live heartbeatmonitoring, and several different alert systems. Many of these devices simultaneously share data to form anautomated system. The data shared between machine-type communication devices (MTCDs) is prone to risk dueto limited computational power, internal memory, and energy capacity. Therefore, securing the data and devicesbecomes challenging due to factors such as dynamic operational environments, remoteness, harsh conditions,and areas where human physical access is difficult. One of the crucial parts of securing MTCDs and data isauthentication, where each devicemust be verified before data transmission. SeveralM2Mauthentication schemeshave been proposed in the literature, however, the literature lacks a comprehensive overview of current M2Mauthentication techniques and the challenges associated with them. To utilize a suitable authentication schemefor specific scenarios, it is important to understand the challenges associated with it. Therefore, this article fillsthis gap by reviewing the state-of-the-art research on authentication schemes in MTCDs specifically concerningapplication categories, security provisions, and performance efficiency.

关键词： Authentication cyber security internet of things machine-type communication devices machine-to-machine communication

树脂基Fe纳米粒子及碳纤维复合吸波平板的制备与性能

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材料工程 2018年第3期46卷 41-47页

作者：周远良赛义德张黎贾韦迪段玉平董星龙大连理工大学材料科学与工程学院三束材料改性教育部重点实验室辽宁大连116024

以Fe纳米粒子(Fe NPs)为吸波剂,偶联剂KH550为表面改性剂,碳纤维(CFs)作为增强及电磁波反射相,环氧树脂(ER)作为基体,制备多种吸波平板并对其综合性能及相关机制进行研究。结果表明:平板的吸波性能随Fe NPs和CFs含量的增加而提高,吸收... 详细信息

以Fe纳米粒子(Fe NPs)为吸波剂,偶联剂KH550为表面改性剂,碳纤维(CFs)作为增强及电磁波反射相,环氧树脂(ER)作为基体,制备多种吸波平板并对其综合性能及相关机制进行研究。结果表明:平板的吸波性能随Fe NPs和CFs含量的增加而提高,吸收剂浓度梯度分布有助于形成特定频段的共振吸收;平板对电磁波损耗具有明显的各向异性,表现为CFs垂直电磁波入射方向时性能优于平行情况,当Fe NPs的含量为30%(质量分数,下同),CFs为5.52%,板厚为4.56mm时,最小反射损耗为-26.8dB(4.9GHz);同时,CFs可改善平板的抗弯性能,当Fe NPs为30%时,弯曲强度相比于纯树脂时仅降低了5.81%。

关键词： Fe纳米粒子碳纤维环氧树脂浓度梯度微波吸收性能