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Sustainable development has become a big issue in almost all research fields. In water resources system management, if the system is able to satisfy the changing water demand without any system shortage, then sustainability is achieved. In fact, water resources system management is operated under complete uncertainty, with no real possibility to look into the future to predict natural condition, policy, or demand. Due to the increasing problem of scarce water resources, this encourages researchers and experts to manage water resources much more effectively, ensuring all important challenges are resolve and to maintain water resources to guarantee to meet the demand under any condition. This paper discusses the evolution of sustainable development and reviews issues regarding concept, definition, and approach to sustainable development for both research and its application to water resources system management, especially pertaining to water demand fulfillment. The paper describes state of the art simulation and optimization techniques in water resources system management, reviews the growth of simulation and optimization techniques in an effort to establish a sustainable system, frames the progress of such techniques applied to water resources system, and identifies the needs for further development to face the future challenges. This study reviews published articles from 2000 to 2017 in more than 50 peer-reviewed journals, regarding the application of simulation and optimization techniques in water resources system management in relation to sustainable water demand fulfillment by system management. The study showed that water management requires both researchers and practitioners to optimize the limited water availability in fulfillment of the increasing demand for water. Simulation and optimization are promising solutions, and as they are powered by the advancement of computer technology, they have become central to the evolution of these techniques in their application to the sustainable development of water resources system. [ABSTRACT FROM AUTHOR]

Rollovers are complex road accidents causing a big deal of fatalities. FE model for rollover study will costtoo much time due to its long duration. A new multi-body modeling method is proposed in this paper which can save a lot of time and has high-fidelity meanwhile. Following works were carried out to validate this new method. First, a small van was tested following the FMVSS 208 protocol for the validation of the proposed modeling method. Second, a MADYMO model of this small van was reconstructed. The vehicle body was divided into two main parts, the deformable upper body and the rigid lower body, modeled by different waysbased on an FE model. The specific method of modeling is offered in this paper. Finally, the trajectories of the vehicle from test and simulation were compared and the match was very good. Acceleration of left B pillar was taken into consideration, which turned out fitting the test result well in the time of event. The final deformation status of the vehicle in test and simulation showed similar trend. This validated model provides a reliable way for further research in occupant injuries during rollovers. [ABSTRACT FROM AUTHOR]

Understanding how complex phenotypes arise from individual molecules and their interactions is a major challenge in biology and, to meet this challenge, computational approaches are increasingly employed. As an example, a recent paper [1] proposed a whole-cell model Mycoplasma genitalium including all cell components and their interactions. 28 modules representing several cell functions were modeled independently, and then integrated into a single computational model. One assumption considered in the whole-cell model of M.Genitalium is that all 28 modules can be modeled independently given the 1 second step size used in simulations. This is a major assumption, since it simplifies the modeling of several cell functions and makes the modeling of the system as a whole feasible. In this paper we investigate the dependency of experimental results on that assumption. We have simulated the M.Genitalium cell cycle using several simulation time step sizes and compared the results to the ones obtained with the system using 1 second simulation time step. [ABSTRACT FROM AUTHOR]

The pressure regulator is one of the essential parts of Compressed Natural Gas (CNG) powered engines. It reduces the storage pressure (up to 250 bar) from the tank system to a near constant outlet pressure of approximately 2 up to 10 bars within the fuel injection system. A standard mechanical pressure regulator for CNG-powered engines was investigated theoretically and practically, to generate fundamental data for the scientific project described in this paper. Thereto the particular components of such a system were modelled, simulated and verified by comparison of measured and simulated results. Experiments and Simulations are aligned here to validate the model. [ABSTRACT FROM AUTHOR]

Latent heat storage (LHS) has been widely used for energy storage. Compare to sensible heat storage, LHS has several benefits because of its high energy density, small unit sized and operating at low temperature. This paper is aimed to investigate the melting characteristic of phase change material (PCM) implemented in concentric double pipe heat exchanger. The investigation is carried out by both simulation as well as validation. The simulation is conducted using ANSYS FLUENT with double pipe shape of heat storage. The geometrical shape of the storage is double pipe heat exchanger, the PCM is stored in the inner tube meanwhile hot water is circulated in the outer tube. The dimension of the inner tube are 5 cm of diameter and 50 cm length. The diameter of outer tube is 10 cm and 60 cm length. The hot liquid is circulated from the inlet port and withdrawing from the outer port. The inlet and outlet ports are located away at the distance of 5 cm from the edge of the outer tube. The inlet and outlet ports are constructed at the bottom and upper part of the outer tube. The simulation is carried out at temperature 60oC of the hot liquid and flow rate at 4 liters per minute. The validation is also conducted at the same configuration with that on the simulation. The tweaked parameters are number of mesh and mushy-zone value. Results revealed that validation is numerically accepted at deviation less than 5% for melting time deviation. The validation is obtained at number of mesh is 144,000 and mushy-zone value is 1.4x107. On the evaluation of temperature distribution similarity, all of coefficient correlation are obtained greater than 0.8 between simulation and experiment. Being a valid simulation model, it is enabled to be enhanced for predicting melting of phase change materials on the heat energy storage system. [ABSTRACT FROM AUTHOR]

This paper presents using of FlightGear application for flight simulation of a mini-UAV (Unmanned Aerial Vehicle). The first part of the paper is about general information of UAVs and about the fundamentals of airplane flight mechanics. The main section summarizes the information about FlightGear application and describes a way of using the application to simulate a mini-UAV. The process of altitude change by using autopilot has been simulated. In the created simulation, three stage cascade controller was used for an altitude control. Heading was controlled by 2 stage cascade PID (Proportional-Integral-Derivative) controller. An automatic throttle system was applied for a velocity control. The setting of all controllers is included in the description of the simulation. Finally, the results of FlightGear simulation are discussed. [ABSTRACT FROM AUTHOR]

Obtained in the space photos a ground resolution depends on a spacecraft spatial angular motion during optoelectronic survey. The paper studies case of optimal equalization of an image longitudinal velocity in the focal plane of telescope and tackles the problem of defining initial azimuth of the scanning survey under the condition of minimizing quadratic functional of image cross velocity values on edges of the CCD linear array. Results of a simulated survey of random surface object are presented, and the change of initial azimuth value for various survey angles within the swath is examined. The paper presents also a brief description of developed software for designing the space telescope characteristics, simulation and animation of the land-survey spacecraft spatial motion and gives recommendations for its applications. [ABSTRACT FROM AUTHOR]

This paper presents a simulation study of an End-of-Aisle automated storage and retrieval system. Various elements of AS/RS control policies are combined to compare and analyze the performance of an End-of-Aisle automated storage and retrieval system. The extensive simulation study shows the isolated effects of various policies, as well as compares several combinations of policies and rules. This comparison provides a base for selecting the most suitable policy in the evaluated system. [ABSTRACT FROM AUTHOR]

Application of dynamic cellular manufacturing system (DCMS) is a well-known strategy to improve manufacturing efficiency in the production environment with high variety and low volume of production. Often, neither the trade-off of inter and intra-cell material movements nor the trade-off of hiring and firing of operators are examined in details. This paper presents simulation results of an integrated mixed-integer model including sensitivity analysis for several numerical examples. The comprehensive model includes cell formation, inter and intracellular materials handling, inventory and backorder holding, operator assignment (including resource adjustment) and flexible production routing. The model considers multi-production planning with flexible resources (machines and operators) where each period has different demands. The results verify the validity and sensitivity of the proposed model using a genetic algorithm. [ABSTRACT FROM AUTHOR]

In order to solve the problems of Research on NURBS Adaptive Interpolation Technology, such as interpolation time bigger, calculation more complicated, and NURBS curve step error are not easy changed and so on. This paper proposed a study on the algorithm for NURBS adaptive interpolation method of NURBS curve and simulation. We can use NURBS adaptive interpolation that calculates (xi, yi, zi). Simulation results show that the proposed NURBS curve interpolator meets the high-speed and high-accuracy interpolation requirements of CNC systems. The interpolation of NURBS curve should be finished. The simulation results show that the algorithm is correct; it is consistent with a NURBS curve interpolation requirements. [ABSTRACT FROM AUTHOR]

To reduce interpolation time and Max interpolation error in NURBS (Non-Uniform Rational B-Spline) interpolation caused by planning Velocity .This paper proposed a velocity planning interpolation algorithm based on NURBS curve. Firstly, the second-order Taylor expansion is applied on the numerator in NURBS curve representation with parameter curve. Then, velocity planning interpolation algorithm can meet with NURBS curve interpolation. Finally, simulation results show that the proposed NURBS curve interpolator meet the high-speed and high-accuracy interpolation requirements of CNC systems. The interpolation of NURBS curve should be finished. [ABSTRACT FROM AUTHOR]

In order to solve the problems of Newton-Rapson iteration interpolation method of NURBS Curve, Such as interpolation time bigger, calculation more complicated, and NURBS curve step error are not easy changed and so on. This paper proposed a study on the algorithm for Newton-Rapson iteration interpolation method of NURBS curve and simulation. We can use Newton-Rapson iterative that calculate (xi yi, zi). Simulation results show that the proposed NURBS curve interpolator meet the high-speed and high-accuracy interpolation requirements of CNC systems. The interpolation of NURBS curve should be finished. The simulation results show that the algorithm is correct; it is consistent with a NURBS curve interpolation requirements. [ABSTRACT FROM AUTHOR]

The paper addresses the growing need in a simulation-based design verification flow capable to analyze any design of 3D IC stacks and to determine across-die out-of-spec variations in device electrical characteristics caused by layout and through-silicon-via (TSV)/package induced mechanical stress. The limited test and characterization capabilities of 3D IC stacks and a strict "good die" requirement make this type of analysis really critical for the achievement of an acceptable level of functional and parametric yield and reliability. The paper focuses on the development of a design-for-manufacturability (DFM) type of methodology for managing mechanical stresses during a sequence of designs of 3D TSV-based dies, stacks and packages. A set of physics-based compact models for a multi-scale simulation, to assess the mechanical stress across the device layers in silicon dies stacked and packaged with the 3D TSV technology, is proposed. A strategy for a materials data generation to feed simulation and a respective materials characterization approach are proposed, with the goal to establish a database for multi-scale materials parameters of wafer-level and package-level structures. A proposal for model validation based and a calibration approach based on fitting the simulation results to measured local stress components and to electrical characteristics of the test-chip devices are discussed. [ABSTRACT FROM AUTHOR]

Proposed in this paper is a framework of virtual plant model for verification of PLC program by conducting the virtual plant modeling and simulation. The proposed virtual plant model consists of three types of objects: the virtual device model (object model), the intermediary transfer model (functional model) and PLC program (dynamic model). For the implementation of the proposed virtual plant model, this paper employs the I/O model which is based on Automata and Discrete Event System Specifications (DEVS) formalism. By applying an example of the automotive assembly line, nine errors in the PLC code are found and have been revised. With the proposed approach, it will be helpful to reduce the ramp up or down time of the automated manufacturing system. [ABSTRACT FROM AUTHOR]

Research in nanoelectronics poses new challenges for metrology, but advances in theory, simulation and computing and networking technology provide new opportunities to couple simulation and metrology. This paper begins with a brief overview of current work in computational nanoelectronics. Three examples of how computation can assist metrology will then be discussed. The paper concludes with a discussion of how cyberinfrastructure can help connect computing and metrology using the nanoHUB (www.nanoHUB.org) as a specific example. [ABSTRACT FROM AUTHOR]

The establishment of a reliable simulation system for a solar tower power plant can greatly increase the economic and safety performance of the whole system. In this paper, a dynamic model of the 1MWe Solar Tower Power Plant at Badaling in Beijing is developed based on the ?STAR-90? simulation platform, including the heliostat field, the central receiver system (water/steam), etc. The dynamic behavior of the global CSP plant can be simulated. In order to verify the validity of simulation system, a complete experimental process was synchronously simulated by repeating the same operating steps based on the simulation platform, including the locations and number of heliostats, the mass flow of the feed water, etc. According to the simulation and experimental results, some important parameters are taken out to make a deep comparison. The results show that there is good alignment between the simulations and the experimental results and that the error range can be acceptable considering the error of the models. In the end, a comprehensive and deep analysis on the error source is carried out according to the comparative results. [ABSTRACT FROM AUTHOR]

This paper deals with possibilities to validate DEM simulations in the solids conveying zone of single-screw extruders. Apart from determining coefficients of friction, the representation of the pellets' shape is crucial. On the basis of DEM simulations of the bulk density within the screw channel, it is shown that most common plastic pellets can be represented adequately by combining two spheres. Additionally, simulations of the feed opening's pellet flow during a solids conveying process are conducted and validated by comparisons with experimental studies. Good conformity is obtained if the pellets are represented by several spheres as described above. Furthermore, the throughput of simulations and experiments is compared, also yielding good conformity. [ABSTRACT FROM AUTHOR]

In this paper, we concern at situations where we have to compare selected parameters from particular nonlinear models. A motivational examples of previously modelled data are given at the beginning. When comparing parameters from two models, it is possible to combine them into one model. But for three and more models, it is necessary to correct significance level at advance. Two approaches to solving this problem are stated, so-called Šidák correction and Bonferroni method. Results of these methods as well as results coming from the situation where significance level correction is omitted are compared based on simulated data. [ABSTRACT FROM AUTHOR]

WSN can be deployed using widely available hardware and software solutions. The Contiki is an open source operative system compatible with a wide range of WSN hardware. A Contiki development environment named InstantContiki is also available and includes the Cooja simulation tool, useful for the simulation of WSN scenarios, prior to their deployment. This simulation tool can provide realistic results since it uses the full Contiki's source code and some motes can be emulated at the hardware level. However, the Cooja simulator uses one process per simulation, not taking advantage of multiple core processors. In this paper we propose a framework to automate the execution of simulations of multiple scenarios and configurations in Cooja. When a multiple cores processor is available, this framework can run multiple simultaneous Cooja instances, taking advantage of processing resources and contributing to reduce the total simulation runtime. [ABSTRACT FROM AUTHOR]

Laser cutting is a thermal separation process widely used in shaping and contour cutting applications. It is a very fast and at the same time very accurate technology with the optical tool laser not being exposed to any wear. There are, however, gaps in understanding the dynamics of the process, especially with regard to issues related to cut quality. Numerical modeling and simulation of the laser cutting process has shown to improve that understanding without the need for executing a lot of experiments in the real world. In this paper, the utility of a metamodeling technique in gaining valuable information relating to the optimization of a laser cutting process, where a CW laser is used to cut, is analyzed. The numerical simulation itself is characterized by a high dimensional input parameter set. Each parameter has its own range, and thus they are together forming the parameter domain space. The quality criteria, which are predicted with the numerical model, are analyzed together with the parameter domain space and are thus used to optimize the process. However, simulation results can only help in the build-up of process understanding, if they can be presented in their entirety and together with their origin in the parameter domain. For this purpose a new metamodeling concept is presented, which takes the results from numerical simulations and generates a process map, clearly indicating the process domains. [ABSTRACT FROM AUTHOR]

Productivity of the agriculture sector in Iraq has yet to reach an acceptable level. In this paper, we introduce a practical method to help manage Iraqi agriculture sector to control resources and increase production to meet the modern century requirements of good crops. These important resources are identified as water, fertilizer, natural fertilizer, pesticides and labour. The current agricultural patterns in Iraq affect the strategic crops cultivation in the country and lessen agricultural production to some life-threatening limits. Data Envelopment Analysis (DEA), which is a non-parametric tool, is proposed to identify solutions that can maximize farmers' net benefit making an optimal use of the five resources. This model also improves optimal mix of the resources. In reference to the production of each one of the three strategic crops in Iraq, the DEA model is used to find the efficiency of one region among four others in its agriculture sector, with the main problem being the constraint in the number of lands available in the situation. Hence, the simulation technique is used to generate additional regions to the four main regions adopted. This is to resolve the constriction of DEA when the decision making unit is less than the number of variables (outputs and inputs). The result is expected to show the efficiency of each of the evaluated region. [ABSTRACT FROM AUTHOR]

The paper is devoted to simulation of a self-organization process of mesoscopic plastic deformation in polycrystals with transition to macroscopic loading diagrams. The principle of solving an inverse problem in deformable solid mechanics using the relaxation element method is employed. The proposed simulation method allows predicting macroscopic loading diagrams depending on geometric characteristics and physical properties of mesoscopic structural elements as well as with regard to boundary conditions of loading. In this connection' a consideration of stiffness of a loading device acquires a fundamental importance. The obtained dependences are in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Analysis approaches during product development of fluid valves and other aircraft fluid delivery components vary greatly depending on the development stage. Traditionally, empirical or simplistic one-dimensional tools are being deployed during preliminary design, whereas detailed analysis such as CFD (Computational Fluid Dynamics) tools are used to refine a selected design during the detailed design stage. In recent years, combined 1D/3D co-simulation has been deployed specifically for system level simulations requiring an increased level of analysis detail for one or more components. The present paper presents a decoupled 1D/3D analysis approach where 3D CFD analysis results are utilized to enhance the fidelity of a dynamic 1D modelin context of an aircraft fuel valve. [ABSTRACT FROM AUTHOR]

In day-to-day operations, flight delays might happen due to some reason such as bad weather conditions, equipment failure, and limited runway capacity. Flight delays do not only increase crew operating cost, they can cause delay propagation on subsequent flights. Since the crew cost is the second largest cost, it is important to construct a robust flight schedule where any flight delay will not lead to a massive disruption to the subsequent downstream flights. In this paper, we analyze the effect of flight retiming to the robustness of flight schedule. We construct a simulation for measuring the robustness of the flight schedule, where the probability of crew pairing found after a number of flight delays happen is used as the measure of robustness. It is shown that the retiming will increase the robustness of the schedule if we only retime the flights which appear in the first cycle of the set of selected pairings. [ABSTRACT FROM AUTHOR]

Due to the physical limitations on the speed of individual processors, we are currently experiencing a paradigm shift in computer architecture towards multi-processor, multi-core and multi-subcore systems. In order to take full advantage of these new architectures, some of the basic models, algorithms and data structures in Molecular Dynamics simulations need to be re-thought. In this paper, I present some simple, generic algorithmic considerations that can improve the performance of such simulations on the IBM Cell Broadband Engine Architecture, a multi-subcore processor. The accumulated effects of these improvements are on par with what can be achieved with hand-tuned architecture-specific optimizations in the innermost loops of the simulation. [ABSTRACT FROM AUTHOR]

An efficient and fast algorithm, which is based on the splitting-step idea, for simulations of mean-reverting square-root diffusions is presented in this paper. The local path wise error of this algorithm is considered, and an estimate of local error in the 2nd moment is proved. A series of numerical experiments based on MATLAB programs is given to compare the suggested algorithm with the present schemes: the BIM scheme and the BMM scheme. [ABSTRACT FROM AUTHOR]

The aim of this paper is to demonstrate how multilevel tumour growth and response to therapeutic treatment models can be used in order to simulate clinical trials, with the long-term intention of both better designing clinical studies and understanding their outcome based on basic biological science. For this purpose, an already developed computer simulation model of glioblastoma multiforme response to radiotherapy has been used and a clinical study concerning glioblastoma multiforme response to radiotherapy has been simulated. In order to facilitate the simulation of such virtual trials, a toolkit enabling the user-friendly execution of the simulations on grid infrastructures has been designed and developed. The results of the conducted virtual trial are in agreement with the outcome of the real clinical study. [ABSTRACT FROM AUTHOR]

In this paper, the simulation of complicated power electronic systems involving closed-loop control is discussed. The circuit chosen is a Series Resonant dc-dc Converter with closed-loop control of the output voltage. A complex circuit chosen from the power electronics literature has been simulated using the Simpower toolbox of Simulink. The simulation model is described and results pertaining to transient operation of the circuit are presented. [ABSTRACT FROM AUTHOR]

The Exploration Systems Architecture defines missions that require rendezvous, proximity operations, and docking (RPOD) of two spacecraft both in Low Earth Orbit (LEO) and in Low Lunar Orbit (LLO). Uncrewed spacecraft must perform automated and/or autonomous rendezvous, proximity operations and docking operations (commonly known as Automated Rendezvous and Docking, AR&D). The crewed versions may also perform AR&D, possibly with a different level of automation and/or autonomy, and must also provide the crew with relative navigation information for manual piloting. The capabilities of the Rendezvous, Proximity Operations and Docking (RPOD) sensors are critical to the success of the Constellation Program; this is carried as one of the CEV Project top risks. The Exploration Technology Development Program (ETDP) AR&D Sensor Technology Project seeks to reduce this risk by increasing technology maturation of selected relative navigation sensor technologies through testing and simulation. One of the project activities is a series of “pathfinder” testing and simulation activities to integrate relative navigation sensors with the Johnson Space Center Six-Degree-of-Freedom Test System (SDTS). The SDTS will be the primary testing location for the Orion spacecraft's Low Impact Docking System (LIDS). Project team members have integrated the Orion GN&C simulation with the SDTS computer system so that real-time closed loop testing can be performed with relative navigation sensors and the docking system in the loop during docking and undocking scenarios. Two relative navigation sensors are being used as part of a “pathfinder” activity in preparation for future testing with the actual Orion sensors. This paper describes the test configuration and test results. [ABSTRACT FROM AUTHOR]

The RTM/LRI-like processes have gained popularity in the preparation of fibre-reinforced polymer matrix composites because of their high efficiency, low pollution and good reproducibility. With the industry willing to produce more and more complex shape parts with a high fiber volume fraction, void formation is still an open problem in term of prediction. Furthermore, simulation of infusion processes with high permeability draining mediums and very low permeability fabrics is an issue. In this paper, we propose to apply the Constrained Natural Element Method to the resolution of both Stokes and Brinkman equations with flow front progression. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Continued miniaturization in many fields of forming technology implies the need for a better understanding of the effects occurring while scaling down from conventional macroscopic scale to microscale. At microscale, the material can no longer be regarded as a homogeneous continuum because of the presence of only a few grains in the deformation zone. This leads to a change in the material behaviour resulting among others in a large scatter of forming results. A correlation between the integral flow stress of the workpiece and the scatter of the process factors on the one hand and the mean grain size and its standard deviation on the other hand has been observed in experiments. The conventional FE-simulation of scaled down processes is not able to consider the size-effects observed such as the actual reduction of the flow stress, the increasing scatter of the process factors and a local material flow being different to that obtained in the case of macroparts. For that reason, a new simulation model has been developed taking into account all the size-effects. The present paper deals with the theoretical background of the new mesoscopic model, its characteristics like synthetic grain structure generation and the calculation of micro material properties — based on conventional material properties. The verification of the simulation model is done by carrying out various experiments with different mean grain sizes and grain structures but the same geometrical dimensions of the workpiece. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

This paper simulates an impact-echo array technique for the two-dimensional imaging of defects in thick structures such as concrete. A Finite Difference Time Difference (FDTD) Model was employed for the forward model of the impact-echo method. The absorbing boundary conditions were employed for the efficient modeling of the technique. The signals predicted using the FDTD models from a linear array of impact-echo transmitter-receiver system in a multiplexed configuration was used for 2-D image reconstruction of the cross-sectional region of the structure. The reconstruction algorithm uses time shifting (migration) of the signals based on point-source assumption for the impact sources. The images are represented in a typical “B-scan” representation. Several types of defects were simulated and parametric studies on the different parameters that influence the image quality during imaging of defects in concrete structures were examined. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

To enhance the detectability in the phased array UT, it is essential to have well knowledge on the characteristics of ultrasonic waves from array transducers. This paper proposes a mathematical model of the array transducer and a simulation tool to predict the flaw echoes. The modeling of an array transducer is based on the Rayleigh-Sommerfeld integral and the scattered waves from flaws are calculated with the fast multipole BEM (FMBEM). By using the FMBEM, we can solve large scale scattering problems with relatively low computational cost. Here we focus on the transient wave analysis, in which a pulse-shaped wave is used for exciting elements of the array transducer. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

MARS15 is a Monte Carlo code for inclusive and exclusive simulation of three-dimensional hadronic and electromagnetic cascades, muon, heavy-ion, and low-energy neutron transport in accelerator, detector, spacecraft, and shielding components in the energy range from a fraction of an electron volt up to 100 TeV. Main features of the code are described in this paper with a focus on recent developments and benchmarking. Newest developments concern inclusive and exclusive nuclear event generators, extended particle list in both modes, heavy-ion capability electromagnetic interactions, enhanced geometry, tracking, histograming and residual dose modules, improved graphical-user interface, and other external interfaces. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

This paper presents a method of warehouse simulation model implementation using concepts of virtual reality (VR). The basic idea is to compare the “Real Process” controlled by operator with his/her heuristics with the “Virtual Process” represented by a simulation model, controlled by the optimization algorithm. The optimization algorithm is based on a SD model of the warehouse and decision support module. The SD warehouse model represents the abstraction of “Virtual Process” and is considered to be a model of a model. The state of the “Virtual Process” is controlled with help of a decision support module and is compared with the state of the “Real Process” on the basis of actual information regarding the state of warehouse. This concept is useful for predictive model validation, where the parallel observation of the actual system and the virtual one takes place at the same time, and for the optimization algorithm migration into practice. For the simulation mathematical tool Matlab was used. Several ordering strategies were analyzed with a goal of producing lower total warehousing costs than the actual costs provided by the observed company. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The a⁁ versus a method, which is based on simple linear regression analysis, is commonly used to quantify inspection probability of detection (POD). Bias in flaw sizing will, however, cause bias in POD estimates. This paper describes a statistical model for adjusting for bias in POD estimates that is caused by flaw sizing errors. The model is fit by using the method of maximum likelihood. Our simulation studies that show how the use of our model will adjust for flaw-sizing bias. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In logistics and industrial production managers must deal with the impact of stochastic events to improve performances and reduce costs. In fact, production and logistics systems are generally designed considering some parameters as deterministically distributed. While this assumption is mostly used for preliminary prototyping, it is sometimes also retained during the final design stage, and especially for estimated parameters (i.e. Market Request). The proposed methodology can determine the impact of stochastic events in the system by evaluating the chaotic threshold level. Such an approach, based on the application of a new and innovative methodology, can be implemented to find the condition under which chaos makes the system become uncontrollable. Starting from problem identification and risk assessment, several classification techniques are used to carry out an effect analysis and contingency plan estimation. In this paper the authors illustrate the methodology with respect to a real industrial case: a production problem related to the logistics of distributed chemical processing. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The GLAST Burst Monitor (GBM) is designed to provide wide field of view observations of gamma-ray bursts and other fast transient sources in the energy range 10 keV to 30 MeV. The GBM is composed of several unshielded and uncollimated scintillation detectors (twelve NaI and two BGO) that are widely dispersed about the GLAST spacecraft. As a result, reconstructing source locations, energy spectra, and temporal properties from GBM data requires detailed knowledge of the detectors’ response to both direct radiation as well as that scattered from the spacecraft and Earth’s atmosphere. This full GBM instrument response will be captured in the form of a response function database that is derived from computer modeling and simulation. The simulation system is based on the GEANT4 Monte Carlo radiation transport simulation toolset, and is being extensively validated against calibrated experimental GBM data. We discuss the architecture of the GBM simulation and modeling system and describe how its products will be used for analysis of observed GBM data. Companion papers describe the status of validating the system. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]