215 research outputs found
An Agent-Based Simulation API for Speculative PDES Runtime Environments
Agent-Based Modeling and Simulation (ABMS) is an effective paradigm to model systems exhibiting complex interactions, also with the goal of studying the emergent behavior of these systems. While ABMS has been effectively used in many disciplines, many successful models are still run only sequentially. Relying on simple and easy-to-use languages such as NetLogo limits the possibility to benefit from more effective runtime paradigms, such as speculative Parallel Discrete Event Simulation (PDES). In this paper, we discuss a semantically-rich API allowing to implement Agent-Based Models in a simple and effective way. We also describe the critical points which should be taken into account to implement this API in a speculative PDES environment, to scale up simulations on distributed massively-parallel clusters. We present an experimental assessment showing how our proposal allows to implement complicated interactions with a reduced complexity, while delivering a non-negligible performance increase
Towards a framework for sustainable development planning in the Indonesian natural rubber industry supply network
Supply networks for natural resources such as rubber present significant opportunities to deliver global sustainability goals by reducing environmental, social and economic impacts of industrial activities. This research is using the Indonesian natural rubber industry as a case study. Early discussions with stakeholders highlighted a need for decision support tools to facilitate sustainability-related trade-offs in industry-wide and firm-level planning processes. The example used in this paper relates to rubber plantation replanting programmes and a three-way trade-off between customers’ needs for a steady flow of rubber, an industry need to improve its environmental sustainability and rubber plantation owners’ needs to maintain their financial sustainability which, in turn, influences social sustainability. An initial framework for sustainable development planning based on the case study and literature is proposed, and its use in the design of a computational simulation experiment using hybrid simulation models to predict the sustainability impacts of alternative replanting scenarios is reported
A conceptual framework of volcanic evacuation simulation of Merapi using agent-based model and GIS
In volcanic crises, the ability of population to evacuate has important role to reduce the risk. Based on two experiences of crisis management of Merapi 2006 and 2010, it was reported that there are problems in this aspect that caused confusion of population during the crises which resulted in fatalities. Therefore, we propose a methodology to develop a simulation model to analyze population risk that can be used to highlight the probabilities of emerged problem during the evacuation. The methodology of this research will be highly relied on the GIS-ABM simulation. The simulation was developed from the relation of the volcano, surrounding population and stakeholder within the environmental system. Those elements are represented as agents with their attributes, roles, behaviour and properties. As an example of the application, we developed a simulation case study using Anylogic
Modeling good research practices - overview: a report of the ISPOR-SMDM modeling good research practices task force - 1.
Models—mathematical frameworks that facilitate estimation of the consequences of health care decisions—have become essential tools for health technology assessment. Evolution of the methods since the first ISPOR modeling task force reported in 2003 has led to a new task force, jointly convened with the Society for Medical Decision Making, and this series of seven papers presents the updated recommendations for best practices in conceptualizing models; implementing state–transition approaches, discrete event simulations, or dynamic transmission models; dealing with uncertainty; and validating and reporting models transparently. This overview introduces the work of the task force, provides all the recommendations, and discusses some quandaries that require further elucidation. The audience for these papers includes those who build models, stakeholders who utilize their results, and, indeed, anyone concerned with the use of models to support decision making
Spectroscopic assessment of charge mobility in organic semiconductors
Rapid progress in organic electronics demands new highly efficient organic
semiconducting materials. Nevertheless, only few materials have been created so
far that show reliable band-like transport with high charge mobilities, which
reflects the two main obstacles in the field: the poor understanding of charge
transport in organic semiconductors (OSs) and the difficulty of its
quantification in devices. Here, we present a spectroscopic method for
assessment of the charge transport in organic semiconductors. We show that the
intensities of the low-frequency Raman spectrum allow calculation of the
dynamic disorder that limits the charge carrier mobility. The spectroscopically
evaluated mobility clearly correlates with the device charge mobility reported
for various OSs. The proposed spectroscopic method can serve as a powerful tool
for a focused search of new materials and highlights the disorder bottleneck in
the intrinsic charge transport in high-mobility organic semiconductors
How simulation modelling can help reduce the impact of COVID-19
Modelling has been used extensively by all national governments and the World Health Organisation in deciding on the best strategies to pursue in mitigating the effects of COVID-19. Principally these have been epidemiological models aimed at understanding the spread of the disease and the impacts of different interventions. But a global pandemic generates a large number of problems and questions, not just those related to disease transmission, and each requires a different model to find the best solution. In this article we identify challenges resulting from the COVID-19 pandemic and discuss how simulation modelling could help to support decision-makers in making the most informed decisions. Modellers should see the article as a call to arms and decision-makers as a guide to what support is available from the simulation community
Highly Luminescent Solution-Grown Thiophene-Phenylene Co-Oligomer Single Crystals
Thiophene-phenylene co-oligomers (TPCOs) are among the most promising materials for organic light emitting devices. Here we report on record high among TPCO single crystals photoluminescence quantum yield reaching 60%. The solution-grown crystals are stronger luminescent than the vapor-grown ones, in contrast to a common believe that the vapor-processed organic electronic materials show the highest performance. We also demonstrate that the solution grown TPCO single crystals perform in organic field effect transistors as good as the vapor-grown ones. Altogether, the solution-grown TPCO crystals are demonstrated to hold great potential for organic electronics.</p
A System Dynamics Approach for Modeling Return on Quality for ECS Industry
The Electronic Components and Systems industry (ECS) is characterized by long lead times and high market volatility. Besides fast technological development within this industry, cyclic market up- and downturns are influencing the semiconductor market. Therefore, adequate capacity and inventory management as well as continuous process improvements are important success factors for semiconductor companies to be competitive. In this study, the authors focus on a manufacturing excellence approach to increase front-end supply reliability and the availability of inventory within the customer order decoupling point. Here, development and manufacturing processes must be designed in a way that highest levels of product quality, flexibility, time and costs are reached. The purpose of this study is to explore the impact of return on quality in manufacturing systems. Therefore, multimethod simulation modelling including discrete-event and system dynamics simulation is applied
Synthesis and photostability of 1,4-bis(5-phenyloxazol-2-yl)benzene (POPOP) structural isomers and their trimethylsilyl derivatives
In this work, a versatile synthetic method for preparation of linear phenyloxazoles and their organosilicon derivatives under mild conditions via a combination of van Leusen and direct CH arylation reactions is reported. It was used for the synthesis of a novel trimethylsilyl (TMS) derivative of blue laser dye 1,4-bis(5-phenyloxazol-2-yl)benzene (POPOP) and its structural isomer 1,4-bis(2-phenyloxazol-5-yl)benzene (isoPOPOP) with and without TMS substituents. All of the compounds demonstrated high photoluminescence quantum yields and large molar extinction coefficients, which further increased for their TMS derivatives. Measurements of accelerated photodegradation of the dyes in diluted THF solutions revealed that POPOP-type compounds are twice more stable than their isoPOPOP-type isomers, independent of the presence or absence of TMS substituents. Cyclic voltammetry (CV) investigations revealed that POPOP-type dyes are more electrochemically stable as compared to their isoPOPOP-type isomers. Quantum chemical TD DFT calculations of the frontier energy levels of the dyes were in a good agreement with the experimental data obtained by CV. Single-crystal X-ray diffraction experiments revealed significant structural differences between crystal lattices of the dyes. Due to facile synthesis and excellent optical properties as well as high photo- and thermo- stability the novel luminescent dyes may find wide application in organic photonics
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