Simulation

A procedure to compute a probabilistic bound for the maximum tardiness using stochastic simulation

by Atif SHAHZAD

Dr. Nasser MEBARKI

Dispatching rules are widely used to dynamically schedule the operations in a shop. Their
efficiency depends on... more Dispatching rules are widely used to dynamically schedule the operations in a shop. Their
efficiency depends on the performance criteria of interest. One of the most important objectives to deal
with in a manufacturing system is the tardiness which can be measured through several performance
measures. This paper proposes an effective procedure to estimate the first two central moments (i.e., the
mean and the variance) of the conditional tardiness and from this to compute a probabilistic bound for the
maximum tardiness. These estimates are computed from the evaluation of the total tardiness, the number
of tardy jobs and the root mean square tardiness obtained through a stochastic simulation. Different
evaluations done by simulation show the effectiveness of the bound obtained.

Matheuristics: Optimization, Simulation and Control

by Antonio Bolufé

A mathematical basis for simulation of seriatable data

by Irmela Herzog

Co-authored with Irwin Scollar. In: S.P.Q. Rahtz (ed.), Computer Applications and Quantitative Methods in Archaeology, BAR International Series 446(ii), 1988, pp. 53-62.

Modeling and simulation of heat transfer phenomena during investment casting

by Muhammad Musaddique Ali Rafique

International Journal of Heat and Mass Transfer, 52 (2009) 2132-2139.

Determining the heat transfer phenomena during casting processes is an important parameter for measuring
the... more Determining the heat transfer phenomena during casting processes is an important parameter for measuring
the overall performance of process. It gives information about the properties of the metal being
casted and its possible behavior in the mold during casting process. Improper determination of heat
transfer phenomena and use of improper molding materials and casting conditions leads to defects such
as misruns, cold shuts, shrinkage, pin holes, air holes and porosity in final product. A mathematical model
was developed using standard transport equations incorporating all heat transfer coefficients to calculate
the time for solidification of metal in casting and computer simulation of the model was carried out in
C++ to validate the model. The metal used was pure iron casted in investment molds of silica sand with
zircon coating. It was shown that airflow near the mold surfaces was partially restricted due to geometry
of the molds and arrangement of the pieces around a tree. So, the changes in heat transfer coefficient also
contribute towards time of solidification. The time calculated was found to be in good agreement with
experimental values.

The Effects of Computer Simulations On Students’ Success and Attitudes in Teaching Chemistry

by Halil Eksi

Hüsamettin AKÇAY, Burak FEYZ‹O⁄LU,Cengiz TÜYSÜZ
Educational Sciences: Theory & Practice
3 (1) • May›s / May 2003 • 20-26

An important progress in computer technology and software has been realized
in recent years and using of the... more An important progress in computer technology and software has been realized
in recent years and using of the computer in education increased as well as. The
computer-based education (CBE) has been enriched using simulation and
animation. The aim of this study is to carry out the effect of computer
simulation and animation on the students’ success on chemistry subject and
attitudes of students into chemistry. A computer-based learning packet
concerning solutions is prepared for this purpose. The following tests were
applied as pretest before teaching solution chemistry by conventional and
computer-based packet: Achievement test, logical thinking ability test, chemistry
attitudes scale, computer attitudes scale, and simulation attitudes scale. The
study was carried out during 2001-2002 school period with 84 high school
students between ages 15 and 18 of 10th grade. The students were divided into
two groups as Control Group (KG) and Experimental Group (DG) and were
taught using conventional and computer based approaches, respectively.
According to p= 0,05 understanding significance the results indicated that the
experimental group students’ attitudes to computer, to chemistry and to
simulations show a significant and positive change due to students’ control
groups. It’s the same with their success toward chemistry.

A software framework for the rapid development of UAV systems

by Francois du Plessis

S.D. Claassens, J. Meyer

THERMO-MECHANICAL ANALYSIS OF 3-D MULTILAYER STRUCTURES FOR POWER ELECTRONIC DEVICES

by Paolo Emilio Bagnoli

An integrated simulation tool for multilayer stepped pyramidal structures, able to calculate the temperature... more An integrated simulation tool for multilayer stepped pyramidal structures, able to calculate the temperature distributions and thermal stresses at the interfaces between the layers and based on a semi-analytical mathematical strategy is presented. The core of the thermal solver is the analytical simulator DJOSER for power electronic devices. DJOSER is then integrated with a mechanical solver based on the finite element method. A new element is proposed whose geometry is defined by its mean surface and thickness, just like in a plate, and whose mechanical behaviour is fully three-dimensional, in the sense that the deformability in the direction orthogonal to the mean surface is taken into account. The dedicated finite element code developed for solving the equilibrium problem of structures made up of two or more superimposed plates subjected to thermal loads is applied to some two-layer samples made of silicon and copper. The comparisons with the results of standard finite element analyses using a large number of brick elements are presented and discussed.

SymWeb: Modelado de una Aplicación de Simulación Web mediante OOHDM

by Omar Sosa Tzec

The Decision to Implement Self-Service Technology and its Impact on Service Performance and Operating Costs

by Alinda Kokkinou

Grant report

The purpose of this study was to investigate, using simulation, how the implementation of self-service technology in a... more The purpose of this study was to investigate, using simulation, how the implementation of self-service technology in a service delivery process would impact customer waiting times and system operating costs in the context of luxury resort check-in. This required the development of a model linking characteristics of the service delivery process, customer usage and outcomes of interest such as operating costs and waiting times. Three studies were conducted. The purpose of study one was to gain a deeper understanding of the role that SST could play in a resort setting. The purpose of study two was to identify how customers decide between using a service employee and using SST to check-in in a hotel for the purpose of modeling this process. Study three aimed to estimate the impact that SST implementation would have on the performance of an existing process.

Modeling Human Behavior in Customer-based Processes: the Use of Scenario-based Surveys

by Alinda Kokkinou

Paper presented at the 2011 Winter Simulation Conference in Phoenix, AZ

Due to the complex and relatively unpredictable nature of human behavior, customer service-based processes such as... more Due to the complex and relatively unpredictable nature of human behavior, customer service-based processes such as those featured in call centers, restaurants, and hotels can be challenging to model. The present study provides an example of using established theories of customer behavior, in combination with primary data collection, in a time and cost efficient way to model customer decision-making in a particular situation. The context of the study is a hotel check-in process manned by three service employees to which management would like to add a self-service check-in alternative, in order to reduce waiting times. In order to model how customers choose between using the service employee and using the self-service technology, a crucial component of the simulation model, scenario-based surveys are used to supplement existing theories. The simulation study is briefly described and the advantages of this approach are discussed.

Simulating group communication protocols through an object-oriented framework

by Marinho Barcellos

Wind projection basis for real‐time animation of trees

by Julien Diener

@Article{DIENER09,
author = "Diener, Julien and Rodriguez, Mathieu and Baboud, Lionel and Reveret, Lionel",
title = "Wind Projection Basis for Real-Time Animation of Trees",
journal = "Computer Graphics Forum (Proceedings of Eurographics 2009)",
number = "2",
volume = "28",
month = "mar",
year = "2009",
url = http://maverick.inria.fr/Publications/2009/DRBR09,
}

Acquisition et generation du mouvement de plantes

by Julien Diener

High-resolution three-dimensional simulations of mid-ocean ridge hydrothermal systems

by Adriana Paluszny

with Coumou* D, Driesner T, Geiger S, Heinrich CA. Journal of Geophysical Research-Solid Earth, 114,10.1029/2008jb006121.

High-resolution numerical simulations give clear insights into the three-dimensional structure of thermal convection... more High-resolution numerical simulations give clear insights into the three-dimensional structure of thermal convection associated with black-smoker hydrothermal systems. We present a series of simulations that show that, at heat fluxes expected at mid-ocean ridge spreading axes, upflow is focused in circular, pipe-like regions, with the bulk of the recharge taking place in the near-axial region. Recharging fluids have relatively warm temperatures. In this configuration, the system maximizes its heat output, which can be shown to be linked to nonlinearity in the fluid properties. Furthermore, we present a series of simulations with different permeability scenarios. These show that when permeability contrasts are moderate, convection maintains this pipe-like fluid flow structure. The permeability contrast has a dominant effect on flow patters only at early, immature, stages of convection, focussing upflow in high-permeability regions and downflow in low-permeability regions. In such early stages of convection, diffusive vent styles can emerge, which look remarkably similar to diffuse vent fields in natural systems. Finally, simulations in which permeability is defined as a function of temperature indicate that the brittle-ductile condition is likely to occur at temperatures not lower than 650°C. At lower brittle-ductile transition temperatures, the system cannot remove the heat delivered from the magma chamber and vent temperatures are substantially lower than 400°C. This result is in agreement with estimates of the brittle-ductile transition temperature from rock-mechanical studies and the occurrence of earthquakes in the oceanic lithosphere.

Non-Linear Modal Interactions in a Suspension Rope System with Time-Varying Length

by Scott Turner

Journal Applied Mechanics and Materials (Volumes 5 - 6)
Volume Modern Practice in Stress and Vibration Analysis... more Journal Applied Mechanics and Materials (Volumes 5 - 6)
Volume Modern Practice in Stress and Vibration Analysis VI
Pages 217-224
DOI 10.4028/www.scientific.net/AMM.5-6.217
Online since October, 2006
Authors Rodanthi Salamaliki-Simpson, Stefan Kaczmarczyk, Phil Picton, Scott Turner
Keywords Autoparametric Resonance, Modal Interactions, Nonlinear Coupling, Non-Linear System, Suspension Rope, Time-Varying Length
Abstract This paper focuses on the investigation of the autoparametric coupling effects and modal interactions in a suspension rope system with a time varying length. Equations of motion of a multi-degree-of-freedom discrete, non-stationary and non-linear model are presented and are used to analyze the dynamic response of an elevator suspension rope system under resonance conditions. The equations of motion involve quadratic and cubic non-linear terms which are responsible for the modal interaction between the lateral and longitudinal oscillations of the rope and the car motions. The model takes into account the periodic excitations caused by motion of the host structure. The results confirm that adverse responses may arise and internal autoparametric resonance phenomena may occur.

کاربرد مدل ریاضی عددی در مدیریت منابع آب زیر زمینی دشت رامهرمز

by Masoud Saatsaz

مجله علوم دانشگاه شهيد چمران زمستان 1384

دشت رامهرمز از مهمترین قطب های کشاورزی استان خوزستان به شمار می آید. عدم استفاده کامل از پتانسیل آب های زیرزمینی، کاهش... more دشت رامهرمز از مهمترین قطب های کشاورزی استان خوزستان به شمار می آید. عدم استفاده کامل از پتانسیل آب های زیرزمینی، کاهش نزولات جوی و عدم مدیریت در بهره برداری آب های سطحی باعث گردیده که قسمت عمده اراضی قابل کشت دردشت مذکور بلا استفاده باقی مانده و به تدریج براثر فرسایش خاک سطحی، به زمین های بایرتبدیل گردد. از طرفی، کمبود شدید آب برای مصارف کشاورزی مشکلاتی را برای توسعه اقتصادی این مناطق فراهم آورده است. از آن جمله، می توان به بیکاری، فقر و مهاجرت روستاییان اشاره نمود. به همین دلیل برای غلبه بر مشکلات بهره برداری، طرح استفاده توام منابع آب سطحی و زیر زمینی در دشت مطرح گردید. لذا مدل ریاضی MODFLOW به عنوان یک ابزارکارآمد و با صرفه جهت بررسی گزینه های مختلف مدیریتی مورد بررسی و استفاده واقع گردید. ابتدا داده های مختلف هواشناسی، هیدرولوژیکی، زمین شناسی و هیدروژئولوژیکی منطقه جمع آوری و مورد تجزیه تحلیل واقع شد. پس از تهیه مدل مفهومی، داده های لازم در بسته های نرم افزاری مختلف V. MODFLOW. V.2.6 تعریف گردید. سپس واسنجی مدل توسط کد نرم افزاری PEST، مدل مذکور، صحت سنجی شد. نهایتا گزینه های مختلف مدیریتی شامل: ادامه روند کنونی برداشت، توسعه آبخوان با حفر چاه های جدید، تاثیر زهکش ها درمناطق زهدارو بررسی عملکرد آبخوان با انجام عمل انتقال آب و آبیاری مورد بررسی قرارگرفت. بدین ترتیب نتایج حاصل از شبیه سازی نشان می دهد که ادامه روند کنونی برداشت از نظر مدیریتی گزینه قابل قبولی نمی باشد و بر عکس حفر چاه های بهره برداری در مناطق شرقی و مرکزی و اعمال زهکشی در شمال و جنوب دشت گزینه مناسبی برای استفاده توام منابع آب سطحی و زیرزمینی خواهد بود.

Guantánamo Does Not Exist: Simulation and the Production of ‘the Real’ Global War on Terror

by Elspeth Van Veeren

Published in Journal of War and Culture Studies, 2011, 4:2.
Guantánamo, Baudrillard, simulation, War on Terrorism, mediation, spectacle

Joint Task Force Guantánamo, the high-profile U.S. military detention and interrogations facilities was established in... more Joint Task Force Guantánamo, the high-profile U.S. military detention and interrogations facilities was established in January 2002 in order to demonstrate the capture of the ‘worst of the worst’ of Al Qaeda and the Taliban. It nevertheless became a public spectacle that was essential for constituting the reality of the Global War on Terror. Through evolving media and VIP tours of the facilities and the Bush administration’s Military Analyst Program, a system of reverse embeds used to promote Pentagon messages within the U.S. media, Guantánamo became a simulation essential for producing the reality of the war. It became a key way to convince the public that the war was real and necessary, but also that its conduct was just and humane, and by extension, that the U.S. can be understood as ‘good’. Through a triple screen of the tours, the visitors and their mediation, the telegenic spectacle of Guantánamo was transmuted into a reality of Guantánamo as ‘safe, humane, legal, and transparent’. The importance of this for producing understandings of the GWoT bears closer examination. Without this triple screen, Guantánamo does not exist.

Playing at scientists: video games and popularising science

by Merce Oliva

PÉREZ, O.; OLIVA, M.; GUERRERO, F.; CIAURRIZ, F. (2008). “Jugar a científicos: videojuegos y divulgación científica”. Quaderns del CAC, nº 30. pp. 27-36.

What differentiates video games from other audiovisual media for popularising science lies in their capacity to... more What differentiates video games from other audiovisual media for popularising science lies in their capacity to transmit knowledge of complex systems through experimentation and experience. Moreover, as a form of popular culture, video games constitute a particularly interesting vehicle to popularise science. The aim of this article is to analyse the potential and limitations of video
games in terms of popularising science. To do so, the rules of play are analysed, as well as the player’s interactive experience (gameplay) in four commercial video games related to an area of science. The sample selected includes: Crayon Physics, a laboratory of classic mechanics; Trauma Center, where the player adopts the role of surgeon; SimCity 4, on town planning,
and Civilization IV, a journey through universal history.

Report: Simulation of ECOFRAME MAC layer in ns-2.31

by annie gravey

MODELING SETTLEMENT PATTERNS IN REAL TERRITORIES, Advances in Complex Systems (ACS), Volume: 14, Issue: 4(2011) pp. 549-565

by Joaquim Carvalho

Carvalho, J., Lopes, R., Tojo, J.; initally presented at ECCS 2010, Lisbon.

This paper, describes an agent based model of the spreading of a population over a territory. The models aims at... more This paper, describes an agent based model of the spreading of a population over a territory. The models aims at reproducing a distribution of settlements with statistical and spatial characteristics similar to a historically produced pattern. The model operates on a representation of a real territory, taking into account hydrography and relief. The two main goals are to obtain a rank size distribution of the size of settlements which corresponds to a power law (also known as the Zipf Law of settlements) and to place the settlements in the territory in patterns that are close to the real ones, in zones where settlements were the result of a long historical process. The goal of the project was to demonstrate that a set of relatively simple rules could produce a complex pattern, similar to the result of a long and complex historical process. Therefore, it is an assumed reductionist approach.

Our conclusions show that a simple territorial logic, taking into account the quality of land, accessibility, population growth and migration preferences could reproduce Zipf distributions and interesting patterns of agent flow among the settlements created. How- ever, achieving spatial patterns closer to the historical record needs an extra dimension involving field of sight. The best results were achieved by creating an artifical population which chooses to create settlements in places where a wide field of view exists of quality territory.