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Shining the shortest flashes of light on the secret life of electrons

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Advanced Photonics 2023年第6期5卷 5-7页

作者： Margarita Khokhlova Emilio Pisanty Amelle Zaïr King’s College London Department of PhysicsLondonUnited Kingdom

Ever since the invention of laser pulses,^(1–5)one of the key directions for the development of laser technology has been the creation of ever shorter pulses of light.Over the past sixty years,improvements in technology have pushed pulse durations down from nanoseconds through picoseconds to femtoseconds,giving us access to time-resolved studies of molecular nuclear motion and chemical reactions.^(6)Just in time for the 59th birthday of the standard(SI)prefixes“femto”and“atto,”^(7)the 2023 Nobel Prize in Physics was awarded to the latest landmark in this effort:the generation of attosecond pulses of light,^(8–10)which opens a window to the most fundamental timescale of the world around us–the timescale of electrons moving inside atoms,molecules,and condensed matter.

关键词： light shortest flash

shortest Alternate Path Discovery through Recursive Bounding Box Pruning

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Journal of Transportation Technologies 2017年第2期7卷 167-180页

作者： Rajendra S. Parmar Bhushan H. Trivedi Gujarat Technology University (GTU) Ahmedabad India Gujarat Law Society Institute of Computer Technology Ahmedabad India

Congestion is a dynamic phenomenon and hence efficiently computing alternate shortest route can only help expedite decongestion. This research is aimed to efficiently compute shortest path for road traffic network so that congestion can be eased resulting in reduced CO2 emission and improved economy. Congestion detection is achieved after evaluating road capacity and road occupancy. Congestion index, a ratio of road occupancy to road capacity is computed, congestion index higher than 0.6 necessitates computation of alternate shortest route. Various algorithms offer shortest alternate route. The paper discusses minimization of graph based by removing redundant nodes which don’t play a role in computation of shortest path. The proposal is based on continuous definition of a bounding box every time a next neighboring node is considered. This reduces maximum number of contentious nodes repeatedly and optimizes the network. The algorithm is deployed from both the ends sequentially to ensure zero error and validate the shortest path discovery. While discovering shortest path, the algorithm also offers an array of shortest path in ascending order of the path length. However, vehicular traffic exhibits network duality viz. static and dynamic network graphs. shortest route for static distance graph is pre-computed and stored for look-up, alternate shortest path based on assignment of congestion levels to edge weights is triggered by congestion index. The research also supports directed graphs to address traffic rules for lanes having unidirectional and bidirectional traffic.

关键词： Bounding Box Pruning Geometric Containers shortest Alternate Path shortest Path Vehicular Traffic Vehicular Congestion Detection System Vehicular Congestion Detection System

An Investigation on the Effect of Migration Strategy on Parallel GA-Based shortest Path Routing Algorithm

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Communications and Network 2012年第2期4卷 93-100页

作者： Salman Yussof Rina Azlin Razali Department of Systems and Networking College of Information Technology Universiti Tenaga Nasional Kajang Malaysia

Genetic algorithm (GA) is one of the alternative approaches for solving the shortest path routing problem. In previous work, we have developed a coarse-grained parallel GA-based shortest path routing algorithm. With parallel GA, there is a GA operator called migration, where a chromosome is taken from one sub-population to replace a chromosome in another sub-population. Which chromosome to be taken and replaced is subjected to the migration strategy used. There are four different migration strategies that can be employed: best replace worst, best replace random, random replace worst, and random replace random. In this paper, we are going to evaluate the effect of different migration strategies on the parallel GA-based routing algorithm that has been developed in the previous work. Theoretically, the migration strategy best replace worst should perform better than the other strategies. However, result from simulation shows that even though the migration strategy best replace worst performs better most of the time, there are situations when one of the other strategies can perform just as well, or sometimes better.

关键词： Parallel Genetic Algorithm shortest Path Routing Migration Strategy

Solving the constrained shortest path problem using random search strategy

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Science China(Technological Sciences) 2010年第12期53卷 3258-3263页

作者： LI KePing, GAO ZiYou , TANG Tao & YANG LiXing State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing 100044, China State Key Laboratory of Rail Traffic Control and Safety Beijing Jiaotong University Beijing China

In this paper, we propose an improved walk search strategy to solve the constrained shortest path problem. The proposed search strategy is a local search algorithm which explores a network by walker navigating through the network. In order to analyze and evaluate the proposed search strategy, we present the results of three computational studies in which the proposed search algorithm is tested. Moreover, we compare the proposed algorithm with the ant colony algorithm and k shortest paths algorithm. The analysis and comparison results demonstrate that the proposed algorithm is an effective tool for solving the constrained shortest path problem. It can not only be used to solve the optimization problem on a larger network, but also is superior to the ant colony algorithm in terms of the solution time and optimal paths.

关键词： constrained shortest path deterministic random walk optimization

Assessment of POC CD4 Detecting Mode in District or County Labs-Jiangsu Province, China, 2021

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China CDC weekly 2022年第47期4卷 1059-1065,I0003页

作者： Zhi Zhang Xiaoqin Xu Chengqing Sun Jing Lu Haiyang Hu Ying Zhou Gengfeng Fu Department of HIV/STD Control and Prevention Jiangsu Provincial Center for Disease Control and PreventionNanjing CityJiangsu ProvinceChina School of Public Health Nanjing Medical UniversityNanjing CityJiangsu ProvinceChina.

Objective:This study seeks to explore efficient and multiple-item detection modes in new-style HIV labs,as well as access the accuracy and reliability of CD4 cell count detected by point of care(POC)to analyze POC work feasibility in district or county labs.Methods:POC devices adopted in grassroots-level labs and flow cytometers adopted in prefecture-level labs were used to analyze the same group of blood samples.The individual results were collected and compared for parametric tests in correlation and consistency.Results:The Pearson correlation coefficients(r)between results detected by FACSPresto and those by FACSCalibur,FACSVia,FACSCantoII,and EPICSXL were 0.922,0.938,0.914,and 0.823,respectively;the average deviations were−25.64,24.68,3.05,and 70.97 cells/μL,respectively;the Pearson correlation coefficient(r)between results by Pima and FACSCalibur,FACSVia,FACSCantoII,and EPICSXL were 0.900,0.950,0.954,and 0.876,respectively;and the average deviations were−73.99,−40.78,−29.32,and−22.75 cells/μL,respectively.Discussion:Strong positive correlations and good consistency were observed between the CD4 count tested by POC and flow cytometers.These findings provide theoretical support for new-style HIV labs and one-stop services,which can provide shorter testing duration and simpler testing processes,so that the most comprehensive testing results can be obtained in the shortest amount of time.

关键词： testing simpler shortest

Ultrafast Laser Writing Deep inside Silicon with THz-Repetition-Rate Trains of Pulses

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Research 2020年第1期2020卷 1478-1488页

作者： Andong Wang Amlan Das David Grojo Aix-Marseille Univ. CNRSLP3 UMR 734113009 MarseilleFrance

Three-dimensional laser writing inside silicon remains today inaccessible with the shortest infrared light pulses unless complex schemes are used to circumvent screening propagation nonlinearities.Here,we explore a new approach irradiating silicon with trains of femtosecond laser pulses at repetition rates up to 5.6 THz that is order of magnitude higher than any source used for laser processing so far.This extremely high repetition rate is faster than laser energy dissipation from microvolume inside silicon,thus enabling unique capabilities for pulse-to-pulse accumulation of free carriers generated by nonlinear ionization,as well as progressive thermal bandgap closure before any diffusion process comes into play.By space-resolved measurements of energy delivery inside silicon,we evidence changes in the interplay between detrimental nonlinearities and accumulation-based effects.This leads to a net increase on the level of space-time energy localization.The improvement is also supported by experiments demonstrating high performance for 3D laser writing inside silicon.In comparison to repeated single pulses,irradiation with trains of only four-picosecond pulses with the same total energy leads to an apparent decrease of the energy threshold for modification and drastic improvements on the repeatability,uniformity,and symmetricity of the produced features.The unique benefits of THz bursts can provide a new route to meet the challenge of 3D inscription inside narrow bandgap materials.

关键词： repetition Deep shortest

An Evolutionary Algorithm Coupled to an Outranking Method for the Multicriteria shortest Paths Problem

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American Journal of Operations Research 2019年第3期9卷 114-128页

作者： Frédéric Guidana Gazawa Kolyang Irépran Damakoa Department of Mathematics and Computer Science Faculty of Science The University of Ngaoundere Ngaoundere Cameroon Department of Computer Science Higher Teacher’s Training College The University of Maroua Maroua Cameroon Department of Applied Mathematics and Computer Science School of Geology and Mining Engineering The University of Ngaoundere Ngaoundere Cameroon

In this article, we are interested in solving a combinatorial optimization problem, the shortest path problem in a multi-attribute graph, by the out-ranking methods. A multi-attribute graph has simultaneously qualitative and quantitative criteria. This situation gives rise to incomparable paths thus forming the Pareto front. Outranking methods in Multi-criteria Decision Making (MCDM) are the only methods that can take into account this situation (incomparability of actions). After presenting the categories of Multi-criteria Decision Making (MCDM) and the difficulties related to the problems of the shortest paths, we propose an evolutionary algorithm based on the outranking methods to solve the problem of finding “best” paths in a multi-attribute graph with non-additive criteria. Our approach is based on the exploration of induced subgraphs of the outranking graph. Properties have been established to serve as algorithmic basis. Numerical experiments have been carried out and the results presented in this article.

关键词： Multi-Criteria Decision Making Evolutionary Algorithm shortest Path Outranking Method Induced Subgraphs

The Algorithm of the Time-Dependent shortest Path Problem with Time Windows

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Applied Mathematics 2014年第17期5卷 2764-2770页

作者： Nasser A. El-Sherbeny Mathematics Department Faculty of Science Al-Azhar University Cairo Egypt Mathematics Department Faculty of Applied Medical Science Taif University Turabah KSA

In this paper, we present a new algorithm of the time-dependent shortest path problem with time windows. Give a directed graph , where V is a set of nodes, E is a set of edges with a non-negative transit-time function . For each node , a time window ?within which the node may be visited and ?, is non-negative of the service and leaving time of the node. A source node s, a destination node d and a departure time?t0, the time-dependent shortest path problem with time windows asks to find an s, d-path that leaves a source node s at a departure time t0;and minimizes the total arrival time at a destination node d. This formulation generalizes the classical shortest path problem in which ce are constants. Our algorithm of the time windows gave the generalization of the ALT algorithm and A* algorithm for the classical problem according to Goldberg and Harrelson [1], Dreyfus [2] and Hart et al. [3].

关键词： shortest Path Time-Dependent shortest Path ALT Algorithm A* Algorithm Time Windows

Mid-infrared Q-switch performance of ZrC

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Photonics Research 2020年第12期8卷 1857-1861页

作者： YANGYANG LIANG TAO LI WENCHAO QIAO TIANLI FENG SHENGZHI ZHAO YUEFENG ZHAO YUZHI SONG CHRISTIAN KRÄNKEL China Key Laboratory of Laser&Infrared System(Shandong University) Ministry of EducationQingdao 266237China School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and ApplicationShandong UniversityQingdao 266237China Collaborative Innovation Center of Light Manipulations and Applications Shandong Normal UniversityJinan 250358China School of Physics and Electronics Shandong Normal UniversityJinan 250358China Leibniz-lnstitut fur Kristallzuchtung 12489 BerlinGermany

Zirconium carbide(ZrC)with layered structure and nanoparticle morphology was prepared by sonication in an ethyl alcohol solvent.The morphology and saturable absorption properties of the ZrC were systematically analyzed.By using ZrC nanoparticle coated substrates as saturable absorbers,stable Q-switched 3μm Er:Lu_(2)O_(3) lasers were realized.Pulse durations of 50 ns with pulse energies of 20μJ and peak power of 0.4 kW are the shortest obtained with novel-material-based Q-switched lasers in the 3μm wavelength range.

关键词： switched absorber shortest