Current Issue : April - June Volume : 2019 Issue Number : 2 Articles : 5 Articles
In recent years, web technology carried on growing and at same time, the\nnumber of internet users increased significantly in number. Today, a Web\nserver is capable of processing millions of requests per day, but during the\npeak period may collapse and becomes critical causing unavailability of the\nservices offered by the servers. That is why Web server performance is a topic\nof great interest to many researchers. In this paper, we evaluate experimentally\nthe impact of JSP and PHP dynamic content technology: JSP and PHP\nwith access to a database of performance data of Apache Web server. Using\nthe â??ApacheBenchâ? performance measurement tool, the approach is to compare\nthe performances of four different configurations of a Web server, such\nas: Apache Web server implementing JSP technology with access to PostgreSQL\ndatabase, Apache using PHP technology with the PostgreSQL as database,\nApache Web server using the JSP technology with access to MySQL\ndatabase, finally Apache and PHP with DBMS MySQL. At the end of this article,\nwe also present a Simulink model of Web server performance based on\nthe simple M/M/1 queue. During the modeling, the MATLAB software was\nused....
In real life, in different industries, we often deal with systems designed for\nmultiple use for performing single-type tasks. Processes taking place at this\ntime are called service of requirements, and the systems themselvesâ??Queueing\nSystems. This article is dedicated to computer software modelling of\nprocesses taking place in the systems in question, Markov processes in particular.\nIn this article, by means of Matlab environment, software realization of\none of the typical models of queueing service theory-multichannel QS with\nunreliable recoverable servers and limited number of requirements in the\nsystem, is fulfilled. The results of this research are important because it gives\nthe possibility to use received results to determine optimality degree of some\nreal queueing systems that possess Markov property....
Localized impurities doped in the semiconductor substrate of nanostructure devices play an\nessential role in understanding and resolving transport and variability issues in device characteristics.\nModeling discrete impurities under the framework of device simulations is, therefore, an urgent need\nfor reliable prediction of device performance via device simulations. In the present paper, we discuss\nthe details of the physics associated with localized impurities in nanostructure devices, which are\ninherent, yet nontrivial, to any device simulation schemes: The physical interpretation and the role\nof electrostatic Coulomb potential in device simulations are clarified. We then show that a naive\nintroduction of localized impurities into the Poisson equation leads to a logical inconsistency within\nthe framework of the drift-diffusion simulations. We describe a systematic methodology for how to\ntreat the Coulomb potential consistently with both the Poisson and current-continuity (transport)\nequations. The methodology is extended to the case of nanostructure devices so that the effects of the\ninterface between different materials are taken into account....
The integrated Mission Planning System (MPS) of Unmanned Surface Vehicle\n(USV) refers to the process which can recognize, decide, plan situations\nand carry out missions, such as human beings, for all incidental or complex\nevents occurring at sea. In the actual operating environment, it is necessary to\ndevelop a simulation software environment and analyze, verify it in advance\nso as to make an appropriate mission plan considering equipment, sensor,\nfuel, and other available resources. The existing USV mission planning\nprocess methodology has several limitations in the analysis of USV missions\nbecause the scenario to be tested is limited and autonomy of USV is not considered\nsufficiently. To overcome these problems, we constructed a process\nthat considers various missions and is more autonomous, and an integrated\nenvironment in which to experiment. In this study, we designed a multi-agent\nbased USV Integrated Mission Planning System and modeled each component.\nIn addition, we constructed the USV remote operation S/W based on\nM&S that user can experiment with the modeled process and verified the\nusefulness of the developed system through simulations....
G2 lane-change path imposes symmetric conditions on the path geometric properties. This paper presents the comparative study\nof time-optimal velocities to minimize the time needed for traversal of three planar symmetric parametric polynomial lane-change\npaths followed by an autonomous vehicle, assuming that the neighboring lane is free. A simulated model based on unicycle that\naccounts for the acceleration and velocity bounds and is particularly simple for generating the time-optimal path parameterization\nof each lane-change path is adopted. We base the time-optimal trajectory simulations on numerical integration on a path basis\nunder two different end conditions representing sufficient and restricted steering spaces with remarkable difference in allowable\nmaximum curvature. The rest-to-rest lane-change maneuvering simulations highlight the effect of the most relevant path\ngeometric properties on minimal travel time: a faster lane-change curve such as a quintic Bezier curve followed by a unicycle tends\nto be shorter in route length and lower in maximum curvature to have achievable highest speed at the maximum curvature points.\nThe results have implications to path selection for parallel parking and allow the design of continuous acceleration profile via time\nscaling for smooth, faster motion along a given path. This could provide a reference for on-road lane-change trajectory planning\nalong a given path other than parametric polynomials for significantly more complex, complete higher-dimensional highly\nnonlinear dynamic model of autonomous ground vehicle considering aerodynamic forces, tire and friction forces of tire-ground\ninteraction, and terrain topology in real-world....
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