A Framework To Model Complex Systems Via Distributed Simulation: A Case Study Of The Virtual Test Bed Simulation System Using the High Level Architecture

As the size, complexity, and functionality of systems we need to model and simulate con-tinue to increase, benefits such as interoperability and reusability enabled by distributed discrete-event simulation are becoming extremely important in many disciplines, not only military but also many engineering disciplines such as distributed manufacturing, supply chain management, and enterprise engineering, etc. In this dissertation we propose a distributed simulation framework for the development of modeling and the simulation of complex systems. The framework is based on the interoperability of a simulation system enabled by distributed simulation and the gateways which enable Com-mercial Off-the-Shelf (COTS) simulation packages to interconnect to the distributed simulation engine. In the case study of modeling Virtual Test Bed (VTB), the framework has been designed as a distributed simulation to facilitate the integrated execution of different simulations, (shuttle process model, Monte Carlo model, Delay and Scrub Model) each of which is addressing differ-ent mission components as well as other non-simulation applications (Weather Expert System and Virtual Range). Although these models were developed independently and at various times, the original purposes have been seamlessly integrated, and interact with each other through Run-time Infrastructure (RTI) to simulate shuttle launch related processes. This study found that with the framework the defining properties of complex systems - interaction and emergence are realized and that the software life cycle models (including the spiral model and prototyping) can be used as metaphors to manage the complexity of modeling and simulation of the system. The system of systems (a complex system is intrinsically a system of systems ) continuously evolves to accomplish its goals, during the evolution subsystems co-ordinate with one another and adapt with environmental factors such as policies, requirements, and objectives. In the case study we first demonstrate how the legacy models developed in COTS simulation languages/packages and non-simulation tools can be integrated to address a compli-cated system of systems. We then describe the techniques that can be used to display the state of remote federates in a local federate in the High Level Architecture (HLA) based distributed simulation using COTS simulation packages

Multistage Data Selection-based Unsupervised Speaker Adaptation for Personalized Speech Emotion Recognition

This paper proposes an efficient speech emotion recognition (SER) approach that utilizes personal voice data accumulated on personal devices. A representative weakness of conventional SER systems is the user-dependent performance induced by the speaker independent (SI) acoustic model framework. But, handheld communications devices such as smartphones provide a collection of individual voice data, thus providing suitable conditions for personalized SER that is more enhanced than the SI model framework. By taking advantage of personal devices, we propose an efficient personalized SER scheme employing maximum likelihood linear regression (MLLR), a representative speaker adaptation technique. To further advance the conventional MLLR technique for SER tasks, the proposed approach selects useful data that convey emotionally discriminative acoustic characteristics and uses only those data for adaptation. For reliable data selection, we conduct multistage selection using a log-likelihood distance-based measure and a universal background model. On SER experiments based on a Linguistic Data Consortium emotional speech corpus, our approach exhibited superior performance when compared to conventional adaptation techniques as well as the SI model framework

Addressing Complexity Using Distributed Simulation: A Case Study In Spaceport Modeling

As the size, complexity, and functionality of systems to model and simulate continue to increase, benefits such as interoperability and reusability enabled by distributed discrete-event simulation are of interest, especially for distributed manufacturing and enterprise engineering. The High Level Architecture (HLA), a standard distributed simulation environment, is one technology that enables the interconnection of distributed model components. Many applications in industry are developed by a variety of Commercial Off-The-Shelf (COTS) simulation tools, which require some form of gateway to integrate the models into the HLA component-based simulation. This paper summarizes a study conducted to integrate COTS simulation models using gateway tools and visualization of the system states running as part of other simulation models under HLA. The study focused on the prototype of a virtual engineering environment, called the Virtual Test Bed, designed to analyze operations of current and future space vehicles, spaceports, and ranges as a distributed simulation environment

Range Safety Modeling In The Virtual Test Bed

This paper describes the steps taken to incorporate the Virtual Range model into the Virtual Test Bed (VTB) infrastructure. The Virtual Test Bed is a prototype of a virtual engineering environment to study operations of current and future space vehicles, spaceports, and ranges. The High-Level Architecture (HLA), as defined by the Department of Defense, is the main environment. The VTB/HLA implementation described here represents different systems that interact in the simulation of a Space Shuttle liftoff. The Virtual Range model represents the different systems that interact in the determination of the expectation of casualties (Ec) resulting from the toxic effects of the gas dispersion that occurs after a disaster affecting a Space Shuttle within 120 seconds of liftoff. The scope for Ec calculation is restricted to toxic gas dispersion, and we focus on displaying boundaries for Ec = 30x10-6. We have modified the example of the VTB/HLA implementation to add the VR as a third federate. A potential application of this enhanced VTB/HLA implementation is to study the risk associated to existing and contemplated Launch Weather Criteria

Development Of A Virtual Test Bed For Space Operations Using Hla, Xml, And Software Agents

The Virtual Test Bed (VTB) is a distributed environment for spaceport simulation modeling. This distributed environment is the result of the applications of the High-Level Architecture (HLA) and integration frameworks based on software agents and the eXtensible Modeling Language (XML). A distributed environment is needed due to the nature of the different models. This paper provides details of (1) the implementation of a parallel/distributed discrete-event simulation, and (2) the integration of real-time weather to this simulation infrastructure using agents

모바일 클라우드 스토리 서비스에서의 데이터 보안을 위한 데이터 접근 제어 및 보안 키 관리 기법

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A Modeling And Simulation Environment For Space Ranges

This paper describes the Virtual Range project, the goal of which is to determine the population at risk and the expected casualties as a result of toxic gas dispersion when faced with disaster within 120 seconds of an orbiter\u27s liftoff. A user interface provides numerical and graphical summaries of potential outcomes, with user-defined preferences for the display of units of measure, geographic locations, and time values. The system will help local authorities to estimate the population at risk in order to plan for areas to evacuate, and/or for the resources required to provide aid and comfort and to mitigate damages in case of a disaster

A Distributed Environment For Spaceports

This paper describes the development of a distributed environment for spaceport simulation modeling. This distributed environment is the result of the applications of the High-Level Architecture (HLA) and integration frameworks based on software agents and XML. This distributed environment is called the Virtual Test Bed (VTB). A distributed environment is needed due to the nature of the different models needed to represent a spaceport. This paper provides two case studies: one related to the translation of a model from its native environment and the other one related to the integration of real-time weather. Copyright © 2004 SAE International

DFCloud: A TPM-based Secure Data Access Control Method of Cloud Storage in Mobile Devices

Using the cloud storage services, users can access their data in any time, at any place, even with any computing device including mobile devices. Although these properties provide flexibility and scalability in handling data, security issues should be handled especially when mobile devices try to access data stored in cloud storage. Currently, a typical cloud storage service, Dropbox, offers server-side data encryption for security purpose. However, we think such method is not secure enough because all the encryption keys are managed by software and there is no attestation on the client software integrity. Moreover, a simple user identification based on user ID and Password is also easy to be compromised. Data sharing which is critical in enterprise environment is significantly restricted because it is not easy to share encryption key among users. In this paper, we propose DFCloud, a secure data access control method of cloud storage services to handle these problems found in the typical cloud storage service Dropbox. DFCloud relies on Trusted Platform Module (TPM) [1] to manage all the encryption keys and define a key sharing protocol among legal users. We assume that each client is mobile device using ARM TrustZone [2] technology. The DFCloud server prototype is implemented using ARM Fastmodel 7.1 and Open Virtualization software stack for ARM TrustZone. For DFCloud client, TPM functions are developed in the secure domain of ARM TrustZone because most ARM-based mobile devices are not equipped with TPM chip. The DFCloud framework defines TPM-based secure channel setup, TPM-based key management, remote client attestation, and a secure key share protocol across multiple users/devices. It is shown that our concept works correctly through a prototype implementation.1113Nsciescopu

Factors Affecting The Expectation Of Casualties In The Virtual Range Toxicity Model

The Virtual Range (VR) is an environment that integrates in a seamless fashion several models to improve complex systems visualization. A complex system is a non-linear system of systems whose interactions bring together interesting emergent properties that are very difficult to visualize and/or study by using the traditional approach of decomposition. The VR Toxicity Model as described here represents the different systems that interact in the determination of the expectation of casualties (Ec) resulting from the toxic effects of the gas dispersion that occurs after a disaster affecting a Space Shuttle within 120 seconds of liftoff. We present a detailed description of the VR and the factors affecting Ec. The system will help local authorities to estimate the population at risk in order to plan for areas to evacuate and/or for the resources required to provide aid and comfort and mitigate damages in case of a disaster