Using multiple abstraction levels to speedup an MPSoC virtual platform simulator

Virtual platforms are of paramount importance for design space exploration and their usage in early software development and verification is crucial. In particular, enabling accurate and fast simulation is specially useful, but such features are usually conflicting and tradeoffs have to be made. In this paper we describe how we integrated TLM communication mechanisms into a state-of-the-art, cycle-accurate, MPSoC simulation platform. More specifically, we show how we adapted ArchC fast functional instruction set simulators to the MPARM platform in order to achieve both fast simulation speed and accuracy. Our implementation led to a much faster hybrid platform, reaching speedups of up to 2.9 and 2.1x on average with negligible impact on power estimation accuracy (average 3.26% and 2.25% of standard deviation). © 2011 IEEE.

Deviation of Cup and Propeller Anemometer Calibration Results with Air Density

The effect of air density variations on the calibration constants of several models of anemometers has been analyzed. The analysis was based on a series of calibrations between March 2003 and February 2011. Results indicate a linear behavior of both calibration constants with the air density. The effect of changes in air density on the measured wind speed by an anemometer was also studied. The results suggest that there can be an important deviation of the measured wind speed with changes in air density from the one at which the anemometer was calibrated, and therefore the need to take this effect into account when calculating wind power estimations.

Estimación del consumo de potencia en un terminal portátil multimedia basada en la PMU del procesador

Este proyecto se incluye en una línea de trabajo que tiene como objetivo final la optimización de la energía consumida por un dispositivo portátil multimedia mediante la aplicación de técnicas de control realimentado, a partir de una modificación dinámica de la frecuencia de trabajo del procesador y de su tensión de alimentación. La modificación de frecuencia y tensión se realiza a partir de la información de realimentación acerca de la potencia consumida por el dispositivo, lo que supone un problema ya que no suele ser posible la monitorización del consumo de potencia en dispositivos de estas características. Este es el motivo por el que se recurre a la estimación del consumo de potencia, utilizando para ello un modelo de predicción. A partir del número de veces que se producen ciertos eventos en el procesador del dispositivo, el modelo de predicción es capaz de obtener una estimación de la potencia consumida por dicho dispositivo. El trabajo llevado a cabo en este proyecto se centra en la implementación de un modelo de estimación de potencia en el kernel de Linux. La razón por la que la estimación se implementa en el sistema operativo es, en primer lugar para lograr un acceso directo a los contadores del procesador. En segundo lugar, para facilitar la modificación de frecuencia y tensión, una vez obtenida la estimación de potencia, ya que esta también se realiza desde el sistema operativo. Otro motivo para implementar la estimación en el sistema operativo, es que la estimación debe ser independiente de las aplicaciones de usuario. Además, el proceso de estimación se realiza de forma periódica, lo que sería difícil de lograr si no se trabajase desde el sistema operativo. Es imprescindible que la estimación se haga de forma periódica ya que al ser dinámica la modificación de frecuencia y tensión que se pretende implementar, se necesita conocer el consumo de potencia del dispositivo en todo momento. Cabe destacar también, que los algoritmos de control se tienen que diseñar sobre un patrón periódico de actuación. El modelo de estimación de potencia funciona de manera específica para el perfil de consumo generado por una única aplicación determinada, que en este caso es un decodificador de vídeo. Sin embargo, es necesario que funcione de la forma más precisa posible para cada una de las frecuencias de trabajo del procesador, y para el mayor número posible de secuencias de vídeo. Esto es debido a que las sucesivas estimaciones de potencia se pretenden utilizar para llevar a cabo la modificación dinámica de frecuencia, por lo que el modelo debe ser capaz de continuar realizando las estimaciones independientemente de la frecuencia con la que esté trabajando el dispositivo. Para valorar la precisión del modelo de estimación se toman medidas de la potencia consumida por el dispositivo a las distintas frecuencias de trabajo durante la ejecución del decodificador de vídeo. Estas medidas se comparan con las estimaciones de potencia obtenidas durante esas mismas ejecuciones, obteniendo de esta forma el error de predicción cometido por el modelo y realizando las modificaciones y ajustes oportunos en el mismo. ABSTRACT. This project is included in a work line which tries to optimize consumption of handheld multimedia devices by the application of feedback control techniques, from a dynamic modification of the processor work frequency and its voltage. The frequency and voltage modification is performed depending on the feedback information about the device power consumption. This is a problem because normally it is not possible to monitor the power consumption on this kind of devices. This is the reason why a power consumption estimation is used instead, which is obtained from a prediction model. Using the number of times some events occur on the device processor, the prediction model is able to obtain a power consumption estimation of this device. The work done in this project focuses on the implementation of a power estimation model in the Linux kernel. The main reason to implement the estimation in the operating system is to achieve a direct access to the processor counters. The second reason is to facilitate the frequency and voltage modification, because this modification is also done from the operating system. Another reason to implement the estimation in the operating system is because the estimation must be done apart of the user applications. Moreover, the estimation process is done periodically, what is difficult to obtain outside the operating system. It is necessary to make the estimation in a periodic way because the frequency and voltage modification is going to be dynamic, so it needs to know the device power consumption at every time. Also, it is important to say that the control algorithms have to be designed over a periodic pattern of action. The power estimation model works specifically for the consumption profile generated by a single application, which in this case is a video decoder. Nevertheless, it is necessary that the model works as accurate as possible for each frequency available on the processor, and for the greatest number of video sequences. This is because the power estimations are going to be used to modify dynamically the frequency, so the model must be able to work independently of the device frequency. To value the estimation model precision, some measurements of the device power consumption are taken at different frequencies during the video decoder execution. These measurements are compared with the power estimations obtained during that execution, getting the prediction error committed by the model, and if it is necessary, making modifications and settings on this model.

Component reliability estimations without field data

Maintenance activities in a large-scale engineering system are usually scheduled according to the lifetimes of various components in order to ensure the overall reliability of the system. Lifetimes of components can be deduced by the corresponding probability distributions with parameters estimated from past failure data. While failure data of the components is not always readily available, the engineers have to be content with the primitive information from the manufacturers only, such as the mean and standard deviation of lifetime, to plan for the maintenance activities. In this paper, the moment-based piecewise polynomial model (MPPM) are proposed to estimate the parameters of the reliability probability distribution of the products when only the mean and standard deviation of the product lifetime are known. This method employs a group of polynomial functions to estimate the two parameters of the Weibull Distribution according to the mathematical relationship between the shape parameter of two-parameters Weibull Distribution and the ratio of mean and standard deviation. Tests are carried out to evaluate the validity and accuracy of the proposed methods with discussions on its suitability of applications. The proposed method is particularly useful for reliability-critical systems, such as railway and power systems, in which the maintenance activities are scheduled according to the expected lifetimes of the system components.

Fabrication and analysis of 2x2 thermo-optic SOI waveguide switch with low power consumption and fast response by anisotropy chemical etching

A low power consumption 2 x 2 thermo-optic switch with fast response was fabricated on silicon-on-insulator by anisotropy chemical etching. Blocking trenches were etched on both sides of the phase-shifting arms to shorten device length and reduce power consumption. Thin top cladding layer was grown to reduce power consumption and switching time. The device showed good characteristics, including a low switching power of 145 mW and a fast switching speed of 8 +/- 1 mus, respectively. Two-dimensional finite element method was applied to simulate temperature field in the phase-shifting arm instead of conventional one-dimensional method. According to the simulated result, a new two-dimensional index distribution of phase-shifting arm was determined. Consequently finite-difference beam propagation method was employed to simulate the light propagation in the switch, and calculate the power consumption as well as the switching speed. The experimental results were in good agreement with the theoretical estimations. (C) 2004 Elsevier B.V. All rights reserved.

Ship-board measurements and estimations of air-sea fluxes in the western tropical Pacific during TOGA COARE

Direct air-sea flux measurements were made on RN Kexue #1 at 40 degrees S, 156 degrees E during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean-Atmospheric Response Experiment (COARE) Intensive Observation Period (IOP). An array of six accelerometers was used to measure the motion of the anchored ship, and a sonic anemometer and Lyman-alpha hygrometer were used to measure the turbulent wind vector and specific humidity. The contamination of the turbulent wind components by ship motion was largely removed by an improvement of a procedure due to Shao based on the acceleration signals. The scheme of the wind correction for ship motion is briefly outlined. Results are presented from data for the best wind direction relative to the ship to minimize flow distortion effects. Both the time series and the power spectra of the sonic-measured wind components show swell-induced ship motion contamination, which is largely removed by the accelerometer correction scheme, There was less contamination in the longitudinal wind component than in the vertical and transverse components. The spectral characteristics of the surface-layer turbulence properties are compared with those from previous land and ocean results, Momentum and latent heat fluxes were calculated by eddy correlation and compared to those estimated by the inertial dissipation method and the TOGA COARE bulk formula. The estimations of wind stress determined by eddy correlation are smaller than those from the TOGA COARE bulk formula, especially for higher wind speeds, while those from the bulk formula and inertial dissipation technique are generally in agreement. The estimations of latent heal flux from the three different methods are in reasonable agreement. The effect of the correction for ship motion on latent heat fluxes is not as large as on momentum fluxes.

The Seemingly Unrelated Dynamic Cointegration Regression Model and Testing for Purching Power Parity.

This paper studies seemingly unrelated linear models with integrated regressors and stationary errors. By adding leads and lags of the first differences of the regressors and estimating this augmented dynamic regression model by feasible generalized least squares using the long-run covariance matrix, we obtain an efficient estimator of the cointegrating vector that has a limiting mixed normal distribution. Simulation results suggest that this new estimator compares favorably with others already proposed in the literature. We apply these new estimators to the testing of purchasing power parity (PPP) among the G-7 countries. The test based on the efficient estimates rejects the PPP hypothesis for most countries.

Relation between Excitation Power Density and Er3+ Doping Yielding the Highest Absolute Upconversion Quantum Yield

The upconversion quantum yield (UCQY) is one of the most significant parameters for upconverter materials. A high UCQY is essential for a succesful integration of upconversion in many applications, such as harvesting of the solar radiation. However, little is known about which doping level of the rare-earth ions yields the highest UCQY in the different host lattices and what are the underlying causes. Here, we investigate which Er3+ doping yields the highest UCQY in the host lattices β-NaYF4 and Gd2O2S under 4I15/2 → 4I13/2 excitation. We show for both host lattices that the optimum Er3+ doping is not fixed and it actually decreases as the irradiance of the excitation increases. To find the optimum Er3+ doping for a given irradiance, we determined the peak position of the internal UCQY as a function of the average Er−Er distance. For this purpose, we used a fit on experimental data, where the average Er−Er distance was calculated from the Er3+ doping of the upconverter samples and the lattice parameters of the host materials. We observe optimum average Er−Er distances for the host lattices β-NaYF4 and Gd2O2S with differences <14% at the same irradiance levels, whereas the optimum Er3+ doping are around 2× higher for β-NaYF4 than for Gd2O2S. Estimations by extrapolation to higher irradiances indicate that the optimum average Er−Er distance converges to values around 0.88 and 0.83 nm for β-NaYF4 and Gd2O2S, respectively. Our findings point to a fundamental relationship and focusing on the average distance between the active rare-earth ions might be a very efficient way to optimize the doping of rare-earth ions with regard to the highest achievable UCQY.

Relativistic high-current electron-beam stopping-power characterization in solids and plasmas: collisional versus resistive effects.

We present experimental and numerical results on intense-laser-pulse-produced fast electron beams transport through aluminum samples, either solid or compressed and heated by laser-induced planar shock propagation. Thanks to absolute K� yield measurements and its very good agreement with results from numerical simulations, we quantify the collisional and resistive fast electron stopping powers: for electron current densities of � 8 � 1010 A=cm2 they reach 1:5 keV=�m and 0:8 keV=�m, respectively. For higher current densities up to 1012 A=cm2, numerical simulations show resistive and collisional energy losses at comparable levels. Analytical estimations predict the resistive stopping power will be kept on the level of 1 keV=�m for electron current densities of 1014 A=cm2, representative of the full-scale conditions in the fast ignition of inertially confined fusion targets.

Designing Short Term Wave Traces to Assess Wave Power Devices

In recent years modern numerical methods have been employed in the design of Wave Energy Converters (WECs), however the high computational costs associated with their use makes it prohibitive to undertake simulations involving statistically relevant numbers of wave cycles. Experimental tests in wave tanks could also be performed more efficiently and economically if short time traces, consisting of only a few wave cycles, could be used to evaluate the hydrodynamic characteristics of a particular device or design modification. Ideally, accurate estimations of device performance could be made utilizing results obtained from investigations with a relatively small number of wave cycles. However the difficulty here is that many WECs, such as the Oscillating Wave Surge Converter (OWSC), exhibit significant non-linearity in their response. Thus it is challenging to make accurate predictions of annual energy yield for a given spectral sea state using short duration realisations of that sea. This is because the non-linear device response to particular phase couplings of sinusoidal components within those time traces might influence the estimate of mean power capture obtained. As a result it is generally accepted that the most appropriate estimate of mean power capture for a sea state be obtained over many hundreds (or thousands) of wave cycles. This ensures that the potential influence of phase locking is negligible in comparison to the predictions made. In this paper, potential methods of providing reasonable estimates of relative variations in device performance using short duration sea states are introduced. The aim of the work is to establish the shortness of sea state required to provide statistically significant estimations of the mean power capture of a particular type of Wave Energy Converter. The results show that carefully selected wave traces can be used to reliably assess variations in power output due to changes in the hydrodynamic design or wave climate. 

Sustainability of protein production by bioreactor processes using wind and solar power as energy sources

Food production account for significant share of global environmental impacts. Impacts are global warming, fresh water use, land use and some non-renewable substance consumption like phosphorous fertilizers. Because of non-sustainable food production, the world is heading to different crises. Both food- and freshwater crises and also land area and phosphorous fertilizer shortages are one of many challenges to overcome in near future. The major protein sources production amounts, their impacts on environment and uses are show in this thesis. In this thesis, a more sustainable than conventional way of biomass production for food use is introduced. These alternative production methods are photobioreactor process and syngas-based bioreactor process. The processes’ energy consumption and major inputs are viewed. Their environmental impacts are estimated. These estimations are the compared to conventional protein production’s impacts. The outcome of the research is that, the alternative methods can be more sustainable solutions for food production than conventional production. However, more research is needed to verify the exact impacts. Photobioreactor is more sustainable process than syngas-based bioreactor process, but it is more location depended and uses more land area than syngas-based process. In addition, the technology behind syngas-based application is still developing and it can be more efficient in the future.