scholarly journals Assessing the Accuracy of Performance Modelling in Software Defined Networks

2021 ◽  
Author(s):  
◽  
Jordan Ansell
Keyword(s):  
Experimental Measurement ◽  
Network Models ◽  
Analytical Modelling ◽  
Analytical Models ◽  
Queueing Models ◽  
Software Defined Network ◽  
Software Defined Networks ◽  
Performance Modelling ◽  
Experimental Performance ◽  
Performance Results

<p>Analytical modelling and experimental measurement can are used to evaluate the performance of a network. Models provide insight and measurement provides realism.  For software defined networks (SDN) it is unknown how well the existing queueing models represent the performance of a real SDN network. This leads to uncertainty between what can be predicted and the actual behaviour of a software defined network.  This work investigates the accuracy of software defined network queueing models. This is done through comparing the performance results of analytical models to experimental performance results.  The outcome of this is an understanding of how reliable the existing queueing models are and areas where the queueing models can be improved.</p>

scholarly journals Assessing the Accuracy of Performance Modelling in Software Defined Networks

2021 ◽  
Author(s):  
◽  
Jordan Ansell
Keyword(s):  
Experimental Measurement ◽  
Network Models ◽  
Analytical Modelling ◽  
Analytical Models ◽  
Queueing Models ◽  
Software Defined Network ◽  
Software Defined Networks ◽  
Performance Modelling ◽  
Experimental Performance ◽  
Performance Results

<p>Analytical modelling and experimental measurement can are used to evaluate the performance of a network. Models provide insight and measurement provides realism.  For software defined networks (SDN) it is unknown how well the existing queueing models represent the performance of a real SDN network. This leads to uncertainty between what can be predicted and the actual behaviour of a software defined network.  This work investigates the accuracy of software defined network queueing models. This is done through comparing the performance results of analytical models to experimental performance results.  The outcome of this is an understanding of how reliable the existing queueing models are and areas where the queueing models can be improved.</p>

IMPLEMENTING FAST FOURIER TRANSFORMS ON DISTRIBUTED-MEMORY MULTIPROCESSSORS USING DATA REDISTRIBUTIONS

1994 ◽  
Vol 04 (04) ◽  
pp. 477-488 ◽  
Author(s):  
S.K.S. GUPTA ◽  
C.-H. HUANG ◽  
P. SADAYAPPAN ◽  
R.W. JOHNSON
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Distributed Memory ◽  
Fourier Transforms ◽  
Experimental Performance ◽  
Minimum Number ◽  
Data Redistribution ◽  
Using Data ◽  
Performance Results ◽  
Fft Algorithms

Implementations of various fast Fourier transform (FFT) algorithms are presented for distributed-memory multiprocessors. These algorithms use data redistribution to localize the computation. The goal is to optimize communication cost by using a minimum number of redistribution steps. Both analytical and experimental performance results on the Intel iPSC/860 system are presented.

A Numerical and Experimental Performance Comparison of an 86 MM Radial and Back Swept Turbine

2009 ◽  
Author(s):  
Liam Barr ◽  
Stephen Spence ◽  
David Thornhill ◽  
Paul Eynon
Keyword(s):  
Numerical Models ◽  
Performance Comparison ◽  
Point Of View ◽  
Blade Angle ◽  
Experimental Performance ◽  
Numerical Predictions ◽  
Radial Turbine ◽  
Optimum Velocity ◽  
Performance Results ◽  
Performance Gains

This report details the numerical and experimental investigation of the performance characteristics of a conventional radial turbine compared with a new back swept design for the same application. The blade geometry of an existing turbine from a turbocharger was used as a baseline. A new back swept blade was subsequently designed for the rotor, which departed from the conventional radial inlet blade angle to incorporate a 25° inlet blade angle. A comparative numerical analysis between the two geometries is presented. Results show that the 25° back swept blade offers significant increases in efficiency while operating at lower than optimum velocity ratios (U/C). Improvements in efficiency at off-design conditions could significantly improve turbocharger performance since the turbine typically experiences lower than optimum velocity ratios while accelerating during engine transients. A commercial CFD code was used to construct single passage steady state numerical models. The numerical predictions show off-design performance gains of 2% can be achieved, while maintaining design point efficiency. A finite element stress analysis was conducted to show that the nonradial inlet blade angle could be implemented without exceeding the acceptable stress levels for the rotor. A modal analysis was also carried out in order to identify the natural blade frequencies, showing that these were not significantly changed by the implementation of backswept blading. A prototype backswept rotor was produced and tested in a direct comparison with the baseline rotor geometry. Experimental performance results showed strong correlations with those obtained numerically, and verified the predicted performance gains at off-deign velocity ratios. This numerical and experimental study has shown that it is feasible from both an aerodynamic and structural point of view to improve the performance characteristic of a radial turbine at lower than optimum velocity ratios through the implementation of back swept blading.

Experimental Measurement of Inter-Die Thermal Resistance in a Two Die 3D IC

2016 ◽  
Author(s):  
Leila Choobineh ◽  
Ankur Jain ◽  
Jared Jones
Keyword(s):  
Thermal Resistance ◽  
Experimental Measurement ◽  
High Speed ◽  
Thermal Design ◽  
Analytical Models ◽  
Physical Parameters ◽  
3D Ic ◽  
3D Ics ◽  
High Speed Data Acquisition ◽  
High Speed Data

Thermal modeling and temperature prediction in 3D ICs are important for improving performance and reliability. A number of numerical and analytical models have been developed for thermal analysis of 3D ICs. However, there is a relative lack of experimental work to determine key physical parameters in 3D IC thermal design. One such important key parameter is the inter-die thermal resistance between adjacent die bonded together. This paper describes a novel experimental method to measure the value of inter-die thermal resistance between two die in a 3D IC. The effect of heating one die on the temperature of the other die in a two-die stack is measured over a short time period using high speed data acquisition to negate the effect of boundary conditions. Numerical simulation is performed and based on a comparison between experimental data and the numerical model, the inter-die thermal resistance between two die is determined. There is good agreement between experimental measurement and theoretically estimated value of the inter-die thermal resistance. Results from this paper are expected to assist in thermal design and management of 3D ICs.

scholarly journals Application of queueing models with abandonment for Call Center congestion analysis

2020 ◽  
Vol 27 (1) ◽  
Author(s):  
Sidney Carlos Ferrari ◽  
Reinaldo Morabito
Keyword(s):  
Call Center ◽  
Call Centers ◽  
Queueing Systems ◽  
Minimum Cost ◽  
Service Organizations ◽  
Analytical Models ◽  
Queueing Models ◽  
Phone Calls ◽  
Using Data ◽  
Mixed Distributions

Abstract This paper studies and applies queueing systems to Call Centers regarding the possibility of customer abandonment from the system before being served due to their impatience in waiting for a service. Call Centers are service organizations that predominantly serve customers via phone calls. One of the main concerns in managing them is to provide quality service at a minimum cost. Noticing the quality of services offered is expressed by customers, for example by abandonment from the queue. This paper shows that the M/M/c+G analytical queueing models with abandonment, with patience time represented by generic distributions (particularly mixed distributions), are more effective than the M/M/c+M analytical queueing models with abandonment, with Exponential patience, commonly used to evaluate congestion problems in Call Centers and support sizing and operational decisions in these systems. We conducted a study using data extracted from a Bank Call Center located in Israel and the parameters and some performance measures are determined based on this data. These sampling measures are compared with the same measures achieved by the M/M/c+M and M/M/c+G analytical queueing models considered in this research, which use parameters obtained empirically and the mixed and non-mixed distributions based on Exponential and Lognormal to represent user patience. An experimental discrete simulation model was also used to explore an alternative scenario, showing the potential of using the approaches based on analytical models with abandonment for Call Center analysis.

scholarly journals An Ontological Security Framework to Secure the SDN based IoT Networks

2021 ◽  
Vol 5 (1) ◽  
pp. 4-18
Author(s):  
Nazmul Hossain ◽  
Md Zobayer Hossain ◽  
Md Alam Hossain
Keyword(s):  
Internet Of Things ◽  
Network Model ◽  
Security Architecture ◽  
Software Defined Network ◽  
Software Defined Networks ◽  
Network Development ◽  
Ontological Security ◽  
Security Framework ◽  
Network Infrastructure ◽  
Iot Devices

The IoT (Internet of Things) is now a trendy technology with its numerous apps in multiple areas. It includes a heterogeneous amount of Internet and mutually linked devices. Since the IoT network is characterized by tiny assets that produce less energy and are more flexible, this number of machines is difficult to monitor. SDN (Software Defined Network) is a new network model that facilitates the creation and introduction of fresh networking abstractions, simplifies the management of network and facilitates network development. In this paper, by leveraging the fundamental characteristics represented by Software Defined Networks (SDN), we present an ontological security architecture for IoT networks. Our security architecture restricts access to independently verified IoT devices via the network. To secure the flows in the IoT network infrastructure, we introduced an extra layer and provide a lightweight protocol to authenticate IoT systems. Such an advanced strategy to protection containing IoT device authentication and allowing approved flows can assist secure IoT networks against malicious IoT devices and threats.

Review of the Role of Analytical Modelling Methods in Riverbank Filtration System

2014 ◽  
Vol 71 (1) ◽  
Author(s):  
Shaymaa Mustafa ◽  
Arifah Bahar ◽  
Zainal Abdul Aziz ◽  
Saim Suratman
Keyword(s):  
Point Of View ◽  
Analytical Modelling ◽  
Analytical Models ◽  
Riverbank Filtration ◽  
Stream Depletion ◽  
Filtration System ◽  
Depletion Rate ◽  
Contaminants Transport ◽  
Modelling Methods

Riverbank filtration (RBF) technology is applied in several countries around the world as one of the main sources of drinking water supply both from quantitative and qualitative point of view. Consequently, several analytical modelling methods, mostly based on the transformation techniques, are developed in literature to describe different processes which occur in RBF system. An extensive overview of these analytical methods, their uses and limitations are discussed. The review disclosed that most analytical models usually are concerned in evaluating stream depletion rate rather than contaminants transport especially the transportation of pesticides and pathogens. Laplace and Fourier methods are more popular methods used by researchers to solve the system of partial differential equation that developed to simulate the RBF problem.

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