Potential of biomass energy for electricity generation in sub-Saharan Africa

The paper explores the biomass based power generation potential of Africa. Access to electricity in sub-Saharan Africa (SSA) is about 26% and falls to less than 1% in the rural areas. On the basis of the agricultural and forest produce of this region, the residues generated after processing are estimated for all the countries. The paper also addresses the use of gasification technology - an efficient thermo-chemical process for distributed power generation - either to replace fossil fuel in an existing diesel engine based power generation system or to generate electricity using a gas engine. This approach enables the implementation of electrification programs in the rural sector and gives access to grid quality power. This study estimates power generation potential at about 5000 MW and 10,000 MW by using 30% of residues generated during agro processing and 10% of forest residues from the wood processing industry, respectively. A power generation potential of 15000 MW could generate 100 terawatt-hours (TWh), about 15% of current generation in SSA. The paper also summarizes some of the experience in using the biomass gasification technology for power generation in Africa and India. The paper also highlights the techno economics and key barriers to promotion of biomass energy in sub-Saharan Africa. (C) 2011 International Energy Initiative. Published by Elsevier Inc. All rights reserved.

PIV技术的粒子图像处理方法

以图像相关理论为基础，研究粒子图像测带技术(PIV)的图像处理方法，编制出高精度的处理软件，重建计算模拟的粒子图像位移场，给出了自相关法与互相关法的积相磁与减相关的计算结果，及互相关的误差分析，分析了自相关与互相关区别，得出了互相关法是提高粒子图像测带技术精度的有效方法的结论，因此跨帧技术是PIV技术的发展方向。

Aproximación metodológica a la construcción de entornos virtuales.

Analizar la forma en que actualmente se construyen los entornos virtuales y proponer un marco metodológico que incluye la definición de los elementos de que consta así como los mecanismos asociados a dichos elementos. Los entornos virtuales, son un tipo de sistemas software cuya aplicación en campos como la medicina, la educación, el entretenimiento, el ocio, etc., tiene muy buena acogida. Tanto en las grandes compañías como en los centros de investigación, los entornos virtuales se consideran los sistemas interactivos del futuro. Se prevé que tengan en el siglo XXI la misma repercusión que tuvieron la televisión y la radio en el siglo XX. Se construyen bastantes entornos virtuales. En todos los casos dichos desarrollos son tan rápidos que no da tiempo a desarrollar un conocimiento sobre la construcción sistemática e ingenieril de este tipo de software. En el desarrollo de los entornos virtuales, hay actividades que requieren mucho esfuerzo y tiempo. Dichas actividades se verían aligeradas si se consiguiera reutilizar desarrollos de entornos virtuales previamente. Otro de los grandes problemas es el carácter multidisciplinar de éstos, lo que obliga a que tengan que trabajar juntos equipos humanos provenientes de distintas disciplinas. La comunicación, en estos casos, se complica debido a la disparidad en la formación de los miembros de los equipos de trabajo. La experiencia en el desarrollo de sistemas software constituye el pilar para los desarrollos de forma ingenieril. Al tratar de aplicar la Ingenieria del Software a la construcción de los entornos virtuales quedan otros aspectos del desarrollo de los mismos que se contemplan en la orientación a objetos. Se proponen un conjunto de técnicas y tareas capaces de enriquecer los procesos de desarrollo tradicionales con el fin de que se puedan desarrollar correctamente entornos virtuales y una estrategia de desarrollo estructurada en ciclos que facilita el desarrollo de este tipo de sistemas. Gracias a la aplicación de este marco metodológico, se consiguen desarrollar entornos virtuales en los que la comunicación entre los miembros del equipo de trabajo mejora; cuya trazabilidad permite tanto a los desarrolladores como al jefe de proyecto tener un mejor control sobre el proyecto y donde se fomenta la reutilización entre proyectos de este tipo tanto en fase de diseño como de implementación.

Water-assisted Flow of Heavy Oil in a Vertical Pipe: Pilot-scale Experiments

The use of the core-annular flow pattern, where a thin fluid surrounds a very viscous one, has been suggested as an attractive artificial-lift method for heavy oils in the current Brazilian ultra-deepwater production scenario. This paper reports the pressure drop measurements and the core-annular flow observed in a 2 7/8-inch and 300 meter deep pilot-scale well conveying a mixture of heavy crude oil (2000 mPa.s and 950 kg/m3 at 35 C) and water at several combinations of the individual flow rates. The two-phase pressure drop data are compared with those of single-phase oil flow to assess the gains due to water injection. Another issue is the handling of the core-annular flow once it has been established. High-frequency pressure-gradient signals were collected and a treatment based on the Gabor transform together with neural networks is proposed as a promising solution for monitoring and control. The preliminary results are encouraging. The pilot-scale tests, including long-term experiments, were conducted in order to investigate the applicability of using water to transport heavy oils in actual wells. It represents an important step towards the full scale application of the proposed artificial-lift technology. The registered improvements in terms of oil production rate and pressure drop reductions are remarkable.

The effectiveness and safety of d,l-sotalol in the ambulatory treatment of atrial fibrillation and flutter

Data on short and long term efficacy and safety of d,l sotalol in patients with atrial fibrillation or atrial flutter is limited. The aims of this study were to (1) assess the antiarrhythmic efficacy of d,l sotalol maintaining normal sinus rhythm in patients with refractory atrial fibrillation or flutter, (2) evaluate the efficacy of d,l sotalol in preventing recurrences of paroxysmal atrial fibrillation or flutter, (3) evaluate the control of ventricular rate in patients with paroxysmal or refractory atrial fibrillation or flutter unsuccessfully treated with other antiarrhythmic agents, (4) determine predictors of efficacy (5) assess the safety of d,l sotalol in this setting. Two hundred patients with chronic or paroxysmal atrial fibrillation or atrial flutter or both, who had failed one to six previous antiarrhythmic drug trials were treated with d,l sotalol 80 to 440 mg/day orally. Fifty four percent was female, age 47 +/- 16 years (range 7-79), follow up period 7 +/- 7 months (range 1 to 14 months), 79% of patients had the arrhythmia for more than one year. The atrial fibrillation in 37.5% of patients was chronic and paroxysmal in 23.5. The atrial flutter was chronic in 31% of patients and paroxysmal in 8%. Eighty two percent of patients was in functional class I (NYHA) and 82% had cardiac heart disease: left atrial (LA) size 44 +/- 10 mm, right atrial (RA) size 37 +/- 7 mm and left ventricular ejection fraction (LVEF) 58 +/- 8%. Total success was achieved in 58% of patients (atrial fibrillation 40% and 18% in atrial flutter), partial success in 38% (atrial fibrillation in 18% and 20% in atrial flutter) and 4% of patients failure. It was p < 0.07 when compared total success vs partial success among atrial fibrillation and atrial flutter groups. Patients with cardiac heart disease responded worst (p = 0.10) to the drug than those without it, specially if the heart was dilated. We concluded that d,l sotalol has moderate efficacy to convert and maintain normal sinus rhythm, as well as it acts controlling paroxysmal relapses and ventricular heart rate.