VoIP (Voice over IP (Internet Protocol)) denotes a set of applications that have specific requirements on quality of service (QoS): small loss rate, small delay and jitter. We investigate how different management stra...
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ISBN:
(纸本)0889865264
VoIP (Voice over IP (Internet Protocol)) denotes a set of applications that have specific requirements on quality of service (QoS): small loss rate, small delay and jitter. We investigate how different management strategies such as the queue management scheme, service differentiation (DiffServ) and the use of MPLS help getting the QoS necessary to VoIP applications. We use simulation on Network Simulator (NS) to compare these strategies on various scenarios.
作者：
Bravo, A.Passariello, G.Medina, R.Garreau, M.Grupo de Bioingeniería
Universidad Nacional Experimental Del Táchra Decanato de Investigatión San Cristóbal 5001 Venezuela
Universidad Simón Bolívar Sartenejas Caracas 39000 Venezuela
Universidad de Los Andes Facultad de Ingeniería Mérida 5101 Venezuela
Université de Rennes 1 Campus de Beaulieu 35042 Rennes Cedex France
In this paper, 3-D left ventricle (LV) shapes extracted from the visual human database (VHD) are animated using Free-Form Deformation (FFD) techniques. The starting 3-D shape is obtained after segmentation of endocard...
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ISBN:
(纸本)0889864691
In this paper, 3-D left ventricle (LV) shapes extracted from the visual human database (VHD) are animated using Free-Form Deformation (FFD) techniques. The starting 3-D shape is obtained after segmentation of endocardial and epicardial walls from cryogenic sections of the male VHD. From these contours, endocardial and epicardial walls surfaces are reconstructed using Delaunay triangulation. These surfaces are deformed to simulate the dynamical contraction using FFD techniques guided by prior-knowledge about the left ventricle motion. From the resulting 4-D (3-D + time) shapes, mechanical parameters are calculated and compared with results of works previously reported based in Tagged Magnetic Resonance (MR-tagging) images. Results show a plausible evolution of the left ventricle shape during the cardiac cycle.
A vibration suppression strategy is presented in this paper to implement fast and accurate position control of an elastic robot arm. It is based on a non-uniform lumped mass-spring-damper model of a real, elastic robo...
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A vibration suppression strategy is presented in this paper to implement fast and accurate position control of an elastic robot arm. It is based on a non-uniform lumped mass-spring-damper model of a real, elastic robot arm and the interpretation of vibratory behaviour in the form of waveform propagation and modal response. It allows the endpoint of the elastic robot arm to achieve nearly vibrationless motion with only actuator position feedback, and does not require real-time vibration measurements. From the motion start-up, the controller continuously absorbs the vibratory wave energy inside the elastic robot arm, so as to eliminate the effect of the elastic vibration waves on the endpoint position accuracy. simulation results show that the presented strategy is very good at suppressing the vibration of an elastic robot arm while implementing fast and precise point-to-point control.
We consider a distributed application consisting of processes, which self-control their movement in the network and which need to interact among themselves using communication channel as the base primitive for the int...
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We consider a distributed application consisting of processes, which self-control their movement in the network and which need to interact among themselves using communication channel as the base primitive for the interaction between two processes. The ends of such channel are described with unique ids of processes instead of addresses of nodes where they reside. Two main problems are how to ensure knowledge of valid addresses and how to reduce communication overhead. This paper focuses on these problems in the environment of Active Networks.
In order to facilitate modeling of multi-component systems the multi-physics simulation framework developed earlier by the authors was extended with a concept of a physical component. The approach enables one to model...
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In order to facilitate modeling of multi-component systems the multi-physics simulation framework developed earlier by the authors was extended with a concept of a physical component. The approach enables one to model multiple associations between physical processes and components of the system. This modeling paradigm allows for coexistence of different models in the same region of space, and at the same time provides the possibility to confine some physical processes to certain regions. The approach is well suited for simulations of multi-component media, such as complex engineering systems, as well as biological and geophysical objects. The scope of physical modeling can range from the solution of 3D PDEs to simple ID and 2D approximations. A mixed multi-dimensional modeling is thus possible. The approach was applied to the simulate fuel cells using a combined transport solver in multispecies environment. A number of physical models were solved for different components comprising a typical fuel cell. Models for unsteady fluid dynamics, species and heat transport, electrochemistry and electric currents were combined within different spatial domains and interfaced for common variables at the inter-domain boundaries.
This paper discusses a multi-agent simulation theory which is serving as a formal specification to guide the development of a multi-agent simulation platform. We have extended an existing simulation language: GLIDER, ...
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ISBN:
(纸本)0889865264
This paper discusses a multi-agent simulation theory which is serving as a formal specification to guide the development of a multi-agent simulation platform. We have extended an existing simulation language: GLIDER, with abstractions to model systems where autonomous entities (agents) perceive and act upon their environments. Thus far, we have completed the development of the platform that implements the theory and we are now applying it to the study of multi-agent systems. In particular, an Implementation on Biocomplexity is briefly discussed in the paper.
Global mean sea level is projected to increase by approximately 0.5 meters within the next century. The results of this rise could include the substantial erosion of shorelines, saltwater intrusion into aquifers and e...
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Global mean sea level is projected to increase by approximately 0.5 meters within the next century. The results of this rise could include the substantial erosion of shorelines, saltwater intrusion into aquifers and estuaries, increased fluctuation of tides in bays and rivers, microbiological and chemical contamination in coastal areas, and the amplified intensity and frequency of coastal inundation. The recent tsunami disaster in Southeast Asia reinforces the importance of visualizing the scenarios that could occur as a result of rising seas. Innovative modeling techniques that could be efficiently incorporated into environmental and economic planning would be useful. A Geographic Information System (GIS) that can create, analyze, and display sea level rise scenarios would help local officials address the negative effects of elevated sea levels by allowing them to identify communities that are at risk, assess the situation, and develop mitigation strategies. This paper discusses the issue of rising sea levels at the global and regional scale and illustrates the necessity for public comprehension and involvement. GIS is demonstrated as a means of modeling and disseminating information with the expectation that coastal communities will profit by joining in a process to integrate this knowledge into broad based environmental decision making.
A piece-linear aggregate is used while designing simulation models of systems found in various domains (telecommunication networks, transport, business etc.). In this paper we present a concept of aggregate, consistin...
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A piece-linear aggregate is used while designing simulation models of systems found in various domains (telecommunication networks, transport, business etc.). In this paper we present a concept of aggregate, consisting of l levels and k channels in each level and based on the "cellular" principle. The data generators were implemented to generate the inter-arrival times and servicing times of packets. The aggregate can generate various data flows with different parameters according to exponential, deterministic, uniform distributions or a combination of them. Weibull and Pareto distributions are proposed as alternatives for exponential distribution. In order to show the application of the proposed model, a case study of the Ethernet network presents the aggregate capable of simulating and estimating the characteristics of the Ethernet network.
Discounted cash flow (DCF) analysis is the most accepted approach for company valuation. However, DCF approach presents a number of serious weaknesses when evaluating Internet companies. One of them being how to deal ...
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ISBN:
(纸本)0889864691
Discounted cash flow (DCF) analysis is the most accepted approach for company valuation. However, DCF approach presents a number of serious weaknesses when evaluating Internet companies. One of them being how to deal with high risk and uncertainty, which characterize future cash flows of these companies. Specifically DCF assumes that future cash flow streams are highly predictable. The effects of uncertainty are therefore tackled implicitly by discounting the expected value of the cash flows at a risk-adjusted interest rate. However, under uncertainty, future cash flows of these companies can no longer be characterized by a single value but rather by a range of values of its possible consequences. This paper proposes a Monte Carlo simulation DCF model for valuing an Internet company. The MC simulation DCF model assigns to each key cash flow a range of values in order to cope with uncertainty underlies each variable. The process leads to a probability distribution of the valuation criterion used, giving investors a quantitative measure of risk involved. The paper takes the case of a real Internet company to illustrate the approach and highlight the benefits and the difficulties, which are encountered.
A new technique for power management problem of complex systems will be introduced in this paper. We model a power-managed distributed computing system. We use the Normal distribution to optimization. Experimental res...
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A new technique for power management problem of complex systems will be introduced in this paper. We model a power-managed distributed computing system. We use the Normal distribution to optimization. Experimental results show that the proposed technique can achieve more than 13% power saving compared to other existing DPM techniques.
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