Global ETD Search

11	Time Delay Implies Cost on Task Switching: A Model to Investigate the Efficiency of Task Partitioning Hamann, Heiko, Karsai, Istvan, Schmickl, Thomas 01 July 2013 (has links) Task allocation, and task switching have an important effect on the efficiency of distributed, locally controlled systems such as social insect colonies. Both efficiency and workload distribution are global features of the system which are not directly accessible to workers and can only be sampled locally by an individual in a distributed system. To investigate how the cost of task switching affects global performance we use social wasp societies as a metaphor to construct a simple model system with four interconnected tasks. Our goal is not the accurate description of the behavior of a given species, but to seek general conclusions on the effect of noise and time delay on a behavior that is partitioned into subtasks. In our model a nest structure needs to be constructed by the cooperation of individuals that carry out different tasks: builders, pulp and water foragers, and individuals storing water. We report a simulation study based on a model using delay-differential equations to analyze the trade-off between task switching costs and keeping a high degree of adaptivity in a dynamic, noisy environment. Combining the methods of time-delayed equations and stochastic processes we are able to represent the influence of swarm size and task switching sensitivity. We find that the system is stable for reasonable choices of parameters but shows oscillations for extreme choices of parameters and we find that the system is resilient to perturbations. We identify a trade-off between reaching equilibria of high performance and having short transients. common stomach social crop task partitioning task switching time-delay model Biological Sciences
12	A Benefit-Cost Analysis of a State Freeway Service Patrol: A Florida Case Study Singh, Harkanwal Nain 29 March 2006 (has links) The Road Ranger program is a freeway service patrol (FSP) designed to assist disabled vehicles along congested freeway segments and relieve peak period non-recurring congestion through quick detection, verification and removal of freeway incidents in Florida. It consists of approximately 88 vehicles in fleet and provides free service to about 918 centerline miles. The program is funded by the Florida Department of Transportation (FDOT) and its partners, and is bid out to private contractors. The objective of this study is to examine and evaluate the benefits of the Road Ranger service against their operating costs in five of the seven FDOT Districts and Florida Turnpike Enterprise. The five Districts were chosen due to the availability of Road Ranger program data and activity logs for analysis. The Road Ranger program provides direct benefits to the general public in terms of reduced delay, fuel consumption, air pollution and improved safety and security. The benefits would be expected to be more significant during the peak period when demand reaches or exceeds capacity than in the off-peak and the mid-day period where capacity may not be as significant an issue. The costs considered in this analysis include costs of administration, operation, maintenance, employee salaries, and overhead costs. Incident data were obtained from the daily logs maintained by the Road Ranger service provider containing important information about the time, duration, location, and type of service provided. Other data collected for this study include average daily traffic volume, geometric characteristics of the freeways, unit cost of Road Ranger service, etc. The Freeway Service Patrol Evaluation (FSPE) model developed by the University of California-Berkley was calibrated and used to estimate the benefit-cost ratio for the Road Ranger program. The estimated benefit/cost ratios based on delay and fuel savings indicate that the Road Ranger program produces significant benefits in all the five Districts and Turnpike. The range of benefit-cost ratio of the Road Ranger program in different districts is from 2.3:1 to 41.5:1. The benefit -cost ratio of the entire Road Ranger program is estimated to be in excess of 25:1. Road Rangers Program Traffic Delays Roadway Capacity Incidents FSPE Delay Model Freeway Incident Management American Studies Arts and Humanities Engineering
13	Frequency Synthesis in Wireless and Wireline Systems Turker, Didem 1981- 14 March 2013 (has links) First, a frequency synthesizer for IEEE 802.15.4 / ZigBee transceiver applications that employs dynamic True Single Phase Clocking (TSPC) circuits in its frequency dividers is presented and through the analysis and measurement results of this synthesizer, the need for low power circuit techniques in frequency dividers is discussed. Next, Differential Cascode Voltage-Switch-Logic (DCVSL) based delay cells are explored for implementing radio-frequency (RF) frequency dividers of low power frequency synthesizers. DCVSL ip- ops offer small input and clock capacitance which makes the power consumption of these circuits and their driving stages, very low. We perform a delay analysis of DCVSL circuits and propose a closed-form delay model that predicts the speed of DCVSL circuits with 8 percent worst case accuracy. The proposed delay model also demonstrates that DCVSL circuits suffer from a large low-to-high propagation delay ( PLH) which limits their speed and results in asymmetrical output waveforms. Our proposed enhanced DCVSL, which we call DCVSL-R, solves this delay bottleneck, reducing PLH and achieving faster operation. We implement two ring-oscillator-based voltage controlled oscillators (VCOs) in 0.13 mu m technology with DCVSL and DCVSL-R delay cells. In measurements, for the same oscillation frequency (2.4GHz) and same phase noise (-113dBc/Hz at 10MHz), DCVSL-R VCO consumes 30 percent less power than the DCVSL VCO. We also use the proposed DCVSL-R circuit to implement the 2.4GHz dual-modulus prescaler of a low power frequency synthesizer in 0.18 mu m technology. In measurements, the synthesizer exhibits -135dBc/Hz phase noise at 10MHz offset and 58 mu m settling time with 8.3mW power consumption, only 1.07mWof which is consumed by the dual modulus prescaler and the buffer that drives it. When compared to other dual modulus prescalers with similar division ratios and operating frequencies in literature, DCVSL-R dual modulus prescaler demonstrates the lowest power consumption. An all digital phase locked loop (ADPLL) that operates for a wide range of frequencies to serve as a multi-protocol compatible PLL for microprocessor and serial link applications, is presented. The proposed ADPLL is truly digital and is implemented in a standard complementary metal-oxide-semiconductor (CMOS) technology without any analog/RF or non-scalable components. It addresses the challenges that come along with continuous wide range of operation such as stability and phase frequency detection for a large frequency error range. A proposed multi-bit bidirectional smart shifter serves as the digitally controlled oscillator (DCO) control and tunes the DCO frequency by turning on/off inverter units in a large row/column matrix that constitute the ring oscillator. The smart shifter block is completely digital, consisting of standard cell logic gates, and is capable of tracking the row/column unit availability of the DCO and shifting multiple bits per single update cycle. This enables fast frequency acquisition times without necessitating dual loop fi lter or gear shifting mechanisms. The proposed ADPLL loop architecture does not employ costly, cumbersome DACs or binary to thermometer converters and minimizes loop filter and DCO control complexity. The wide range ADPLL is implemented in 90nm digital CMOS technology and has a 9-bit TDC, the output of which is processed by a 10-bit digital loop filter and a 5-bit smart shifter. In measurements, the synthesizer achieves 2.5GHz-7.3GHz operation while consuming 10mW/GHz power, with an active area of 0.23 mm2. wireline systems wireless systems TDC DCO DPLL ADPLL digital PLL all digital PLL delay model DCVSL VCO ring oscillator prescaler dual modulus prescaler frequency divider PLL frequency synthesizer Frequency Synthesis
14	Random Local Delay Variability : On-chip Measurement And Modeling Das, Bishnu Prasad 06 1900 (has links) This thesis focuses on random local delay variability measurement and its modeling. It explains a circuit technique to measure the individual logic gate delay in silicon to study within-die variation. It also suggests a Process, Voltage and Temperature (PVT)-aware gate delay model for voltage and temperature scalable linear Statistical Static Timing Analysis (SSTA). Technology scaling allows packing billions of transistors inside a single chip. However, it is difficult to fabricate very small transistor with deterministic characteristic which leads to variations. Transistor level random local variations are growing rapidly in each technology generation. However, there is requirement of quantification of variation in silicon. We propose an all-digital circuit technique to measure the on-chip delay of an individual logic gate (both inverting and non-inverting) in its unmodified form based on a reconfigurable ring oscillator structure. A test chip is fabricated in 65nm technology node to show the feasibility of the technique. Delay measurements of different nominally identical inverters in close physical proximity show variations of up to 28% indicating the large impact of local variations. The huge random delay variation in silicon motivates the inclusion of random local process parameters in delay model. In today’s low power design with multiple supply domain leads to non-uniform supply profile. The switching activity across the chip is not uniform which leads to variation of temperature. Accurate timing prediction motivates the necessity of Process, Voltage and Temperature (PVT) aware delay model. We use neural networks, which are well known for their ability to approximate any arbitrary continuous function. We show how the model can be used to derive sensitivities required for voltage and temperature scalable linear SSTA for an arbitrary voltage and temperature point. Using the voltage and temperature scalable linear SSTA on ISCAS 85 benchmark shows promising results with average error in mean delay is less than 1.08% and average error in standard deviation is less than 2.65% and errors in predicting the 99% and 1% probability point are 1.31% and 1% respectively with respect to SPICE. Electronic Gates - Design On-chip Management And Construction Electronic Gate Delay - Modeling Random Local Delay Variation On-chip Gate Delay Measurement Electronic Gate Delay - Measurement Gate Delay Variability Measurement Delay Variability On-chip Measurement Gate Delay Models Electronic Engineering
15	Combustion modeling for virtual SI engine calibration with the help of 0D/3D methods / Verbrennungsmodellierung für die virtuelle Applikation von Ottomotoren unter Verwendung von 0D- und 3D-Methoden Grasreiner, Sebastian 26 July 2012 (has links) (PDF) Spark ignited engines are still important for conventional as well as for hybrid power trains and are thus objective to optimization. Today a lot of functionalities arise from software solutions, which have to be calibrated. Modern engine technologies provide an extensive variability considering their valve train, fuel injection and load control. Thus, calibration efforts are really high and shall be reduced by introduction of virtual methods. In this work a physical 0D combustion model is set up, which can cope with a new generation of spark ignition engines. Therefore, at first cylinder thermodynamics are modeled and validated in the whole engine map with the help of a real-time capable approach. Afterwards an up to date turbulence model is introduced, which is based on a quasi-dimensional k-epsilon-approach and can cope with turbulence production from large scale shearing. A simplified model for ignition delay is implemented which emphasizes the transfer from laminar to turbulent flame propagation after ignition. The modeling is completed with the calculation of overall heat release rates in a 0D entrainment approach with the help of turbulent flame velocities. After validation of all sub-models, the 0D combustion prediction is used in combination with a 1D gas exchange analysis to virtually calibrate the modern engine torque structure and the ECU function for exhaust gas temperature with extensive simulations. / Moderne Ottomotoren spielen heute sowohl in konventionellen als auch hybriden Fahrzeugantrieben eine große Rolle. Aktuelle Konzepte sind hochvariabel bezüglich Ventilsteuerung, Kraftstoffeinspritzung und Laststeuerung und ihre Optimierungspotentiale erwachsen zumeist aus neuen Softwarefunktionen. Deren Applikation ist zeit- und kostenintensiv und soll durch virtuelle Methoden unterstützt werden. In der vorliegenden Arbeit wird ein physikalisches 0D Verbrennungsmodell für Ottomotoren aufgebaut und bis zur praktischen Anwendung geführt. Dafür wurde zuerst die Thermodynamik echtzeitfähig modelliert und im gesamten Motorenkennfeld abgeglichen. Der Aufbau eines neuen Turbulenzmodells auf Basis der quasidimensionalen k-epsilon-Gleichung ermöglicht anschließend, die veränderlichen Einflüsse globaler Ladungsbewegung auf die Turbulenz abzubilden. Für den Brennverzug wurde ein vereinfachtes Modell abgeleitet, welches den Übergang von laminarer zu turbulenter Flammenausbreitung nach der Zündung in den Vordergrund stellt. Der restliche Brennverlauf wird durch die physikalische Ermittlung der turbulenten Brenngeschwindigkeit in einem 0D Entrainment-Ansatz dargestellt. Nach Validierung aller Teilmodelle erfolgt die virtuelle Bedatung der Momentenstruktur und der Abgastemperaturfunktion für das Motorsteuergerät. Ottomotor Variabilität Valvetronic Kraftstoffeinspritzung Direkteinspritzung Benzindirekteinspritzung Laststeuerung Downsizing Aufladung Laststeuerung Applikation Kalibrierung Steuergerät virtuell ECU Verbrennungsmodell 0D Turbulenzmodell k-epsilon Brennverzug Entrainment Momentenstruktur Abgastemperatur spark ignited engines calibration variability valve train Valvetronic fuel direct injection GDI load control turbo charging downsizing virtual methods physical 0D combustion model real-time k-epsilon ignition delay model turbulent burning velocity overall heat release entrainment approach 1D gas exchange analysis engine torque structure ECU exhaust gas temperature simulation ddc:620 Ottomotor Verbrennung Modellierung Motorsteuerung Downsizing Turbulenztheorie Abgastemperatur Fluiddynamik Flammenfront
16	[en] DEVELOPMENT OF A SIMULATION TOOL FOR CELLULAR NETWORK PLANNING AND PERFORMANCE EVALUATION BASED ON THE SIGNALING LOAD / [pt] DESENVOLVIMENTO DE UMA FERRAMENTA DESIMULAÇÃO PARA PLANEJAMENTO E ANÁLISE DO DESEMPENHO DE REDES CELULARES A PARTIR DA CARGA DE SINALIZAÇÃO GERADA RODRIGO CESAR D ALBRIEUX DE CARVALHO 14 June 2002 (has links) [pt] Com o advento dos sistemas celulares de segunda e terceira gerações é esperado que as operadoras se vejam obrigadas a enfrentar um aumento dramático na carga de sinalização que trafega sobre a parte fixa da rede móvel. Apesar disso, são raros os provedores de serviços de comunicações móveis que possuem atualmente a capacidade de prever com relativa precisão o montante desse aumento. Este trabalho apresenta as etapas do desenvolvimento de uma ferramenta de simulação para análise de desempenho de redes de comunicação móvel celular com base na carga de sinalização gerada pelos procedimentos que a mantém em operação. A plataforma de simulação inclui um modelo de mobilidade e teletráfego para caracterizar o processo de geração dos cenários típicos de uma rede móvel celular e um modelo de retardos para representação da rede de sinalização. Ao final do estudo,são apresentados exemplos de aplicação da ferramenta na obtenção de resultados sobre gerência de status, gerência de localização, avaliação da carga de sinalização,dimensionamento da rede de sinalização e análise de desempenho para diferentes configurações de rede. / [en] The advent of second and third generation cellular systems make cellular operators face dramatic increase in the signaling traffic over the fixed part of the mobile network. In spite of this, rare mobile communications service providers are able to forecast the above mention increase and quantify it with reasonable precision. This work describes the development process of a simulation tool for performance analysis of cellular mobile network based on the signaling load generated by the procedures that keeps it working. The simulation platform inlcudes a mobility and teletraffic model to describe the generation process of cellular mobile networks tipical scenarios and a delay model to represent the signaling network. At the end, examples showing the application of the simulation tool to obtain results about status and location management, signaling load evaluation, signaling network planning and performance analysis for different network configurations are presented. [pt] PARAMETROS DE QOS [en] QOS QUALITY OF SERVICE PARAMETERS [pt] SIMULACAO POR EVENTOS DISCRETOS [en] DISCRETE-EVENT SIMULATION [pt] CARGA DE SINALIZACAO [en] COMMUNICATION PROTOCOL [pt] PARTE FIXA DA REDE MOVEL [en] FIXED PART OF THE MOBILE NETWORK [pt] SISTEMA DE SINALIZACAO NO.7 (SS7) [en] SIGNALING SYSTEM NO7 SS7 [pt] IS-14 [en] IS-14 [pt] IS-634 [en] IS-634 [pt] ISUP [en] ISUP [pt] CENARIOS DE OPERACAO DA REDE [en] NETWORK SCENARIOS [pt] MODELO DE MOBILIDADE [en] MOBILITY MODEL [pt] MODELO DE TELEGRAFO [en] TELETRAFFIC MODEL [pt] MODELO DE RETARDOS [en] DELAY MODEL [pt] PLANEJAMENTO DA REDE CELULAR [en] CELLULAR NETWORK PLANNING [pt] ANALISE DE DESEMPENHO [en] PERFORMANCE EVALUATION
17	Combustion modeling for virtual SI engine calibration with the help of 0D/3D methods Grasreiner, Sebastian 06 July 2012 (has links) Spark ignited engines are still important for conventional as well as for hybrid power trains and are thus objective to optimization. Today a lot of functionalities arise from software solutions, which have to be calibrated. Modern engine technologies provide an extensive variability considering their valve train, fuel injection and load control. Thus, calibration efforts are really high and shall be reduced by introduction of virtual methods. In this work a physical 0D combustion model is set up, which can cope with a new generation of spark ignition engines. Therefore, at first cylinder thermodynamics are modeled and validated in the whole engine map with the help of a real-time capable approach. Afterwards an up to date turbulence model is introduced, which is based on a quasi-dimensional k-epsilon-approach and can cope with turbulence production from large scale shearing. A simplified model for ignition delay is implemented which emphasizes the transfer from laminar to turbulent flame propagation after ignition. The modeling is completed with the calculation of overall heat release rates in a 0D entrainment approach with the help of turbulent flame velocities. After validation of all sub-models, the 0D combustion prediction is used in combination with a 1D gas exchange analysis to virtually calibrate the modern engine torque structure and the ECU function for exhaust gas temperature with extensive simulations.:Contents 1 Introduction. 2 Thermodynamic modeling with real-time capability. 3 Quasi-dimensional modeling of turbulence and global charge motion. 4 Physical modeling of ignition delay. 5 Combustion modeling based on a 0D entrainment approach. 6 Virtual engine calibration with a quasi-dimensional combustion model. 7 Summary and outlook. / Moderne Ottomotoren spielen heute sowohl in konventionellen als auch hybriden Fahrzeugantrieben eine große Rolle. Aktuelle Konzepte sind hochvariabel bezüglich Ventilsteuerung, Kraftstoffeinspritzung und Laststeuerung und ihre Optimierungspotentiale erwachsen zumeist aus neuen Softwarefunktionen. Deren Applikation ist zeit- und kostenintensiv und soll durch virtuelle Methoden unterstützt werden. In der vorliegenden Arbeit wird ein physikalisches 0D Verbrennungsmodell für Ottomotoren aufgebaut und bis zur praktischen Anwendung geführt. Dafür wurde zuerst die Thermodynamik echtzeitfähig modelliert und im gesamten Motorenkennfeld abgeglichen. Der Aufbau eines neuen Turbulenzmodells auf Basis der quasidimensionalen k-epsilon-Gleichung ermöglicht anschließend, die veränderlichen Einflüsse globaler Ladungsbewegung auf die Turbulenz abzubilden. Für den Brennverzug wurde ein vereinfachtes Modell abgeleitet, welches den Übergang von laminarer zu turbulenter Flammenausbreitung nach der Zündung in den Vordergrund stellt. Der restliche Brennverlauf wird durch die physikalische Ermittlung der turbulenten Brenngeschwindigkeit in einem 0D Entrainment-Ansatz dargestellt. Nach Validierung aller Teilmodelle erfolgt die virtuelle Bedatung der Momentenstruktur und der Abgastemperaturfunktion für das Motorsteuergerät.:Contents 1 Introduction. 2 Thermodynamic modeling with real-time capability. 3 Quasi-dimensional modeling of turbulence and global charge motion. 4 Physical modeling of ignition delay. 5 Combustion modeling based on a 0D entrainment approach. 6 Virtual engine calibration with a quasi-dimensional combustion model. 7 Summary and outlook. info:eu-repo/classification/ddc/620 ddc:620

Page generated in 0.0442 seconds