Economic study of the wind energy potential in Sahel

International audienceThe wind pattern in Sahel is marked by a strong diurnal cycle as well as a strong seasonal cycle. The low level jet is blowing above the near-surface layer during nighttime and is decoupled from the surface. Nowadays, some studies showed the possibility to use the sub-jet wind at levels higher than 90 m as a source of energy in this area. In the present work, the wind turbines, with hub heights situated at 150 m and blade extremities at 150 ± 60 m, were used to make an economic study of wind energy potential in Sahel. Thus, monthly wind power was determined by two methods. The first involved the wind distributions directly observed. The second was based on the Weibull distributions which were fitted to the data. Day and night were compared. Results showed that this jet was an attractive source of energy provided if huge-capacity energy storage was used. So, the energy stored at night could be restored during the daytime, when the demand is highest. An economic study was done to estimate the number of wind turbines needed to satisfy the Niamey demand. The cost was found reasonably cheap relative to that of other renewable energy sources

Optimizing a calibration software for radio astronomy

With the turn to multicore in chip design and manufacturing, both consumer and high performance applications can benefit from ubiquitous hardware parallelism. However, the performance improvement to be achieved is not always in the orders of magnitude range. In this paper, we present the challenging example of designing a parallel version of a model fitting algorithm used in calibrating telescope observation data in radio astronomy. The complexity of the application, together with the limited opportunities for code modification, bound the performance gain that any parallel system could achieve. However, we show how classical "bound-and-bottleneck" analysis and optimization using multicore architectures help achieving up to 2.3x "wall clock" speedup compared to the original sequential implementation. We further discuss the reasons for this limitation, and suggest possible solutions to address it

A tool for bottleneck analysis and performance prediction for GPU-accelerated applications

High-level tools for analyzing and predicting the performance GPU-accelerated applications are scarce, at best. Although performance modeling approaches for GPUs exist, their complexity makes them virtually impossible to use to quickly analyze the performance of real life applications and obtain easy-to-use, readable feedback. This is why, although GPUs are significant performance boosters in many HPC domains, performance prediction is still based on extensive benchmarking, and performance bottleneck analysis remains a nonsystematic, experience-driven process. In this context, we propose a tool for bottleneck analysis and performance prediction for GPU-accelerated applications. Based on random forest modeling, and using hardware performance counters data, our method can be used to quickly and accurately evaluate application performance on GPU-based systems for different problem characteristics and different hardware generations. We illustrate the benefits of our approach with three detailed use cases: a simple step-by-step example on a parallel reduction kernel, and two classical benchmarks (matrix multiplication and sequence alignment). Our results so far indicate that our statistical modeling is a quick, easy-to-use method to grasp the performance characteristics of applications running on GPUs. Our current work focuses on tackling some of its applicability limitations (more applications, more platforms) and improving its usability (full automation from input to user feedback)

The landscape of GPGPU performance modeling tools

GPUs are gaining fast adoption as high-performance computing architectures, mainly because of their impressive peak performance. Yet most applications only achieve small fractions of this performance. While both programmers and architects have clear opinions about the causes of this performance gap, finding and quantifying the real problems remains a topic for performance modeling tools. In this paper, we sketch the landscape of modern GPUs' performance limiters and optimization opportunities, and dive into details on modeling attempts for GPU-based systems. We highlight the specific features of the relevant contributions in this field, along with the optimization and design spaces they explore. We further use typical kernel examples with various computation and memory access patterns to assess the efficacy and usability of a set of promising approaches. We conclude that the available GPU performance modeling solutions are very sensitive to applications and platform changes, and require significant efforts for tuning and calibration when new analyses are required

Treatment of femoral neck fracture by Moore Prosthesis in Cotonou

Background: Femoral bone neck fracture is a frequent and severe pathology in the elderly. Arthroplasty is the first therapeutic method intended in cases involving the elderly. The Austin Moore arthroplasty is the only method used in our centre in Benin Republic since 1989. The aim of this study is to present our experience. Patients and methods: This retrospective study was performed from January 1997 to December 2004.  There were 37 patients seen at the University Clinic of Traumatology, Orthopedic and Plastic Surgery in Cotonou (National Hospital). Among those 37 cases, 10 have been reviewed after an average period of 7 years.  Results: Most of those patients (90%) were aged over 60 years. Their mean age was 72.4 years. The most common causes of the fracture were falls from height and slipping.  After the operation, 84% of the patients began to walk within the hospitalization period. There was no case of death within the surgery period. The main complication recorded (in 25 % of the cases) is postoperative infection.  Hip function evaluation according to the “Postel-Merle D'aubigne” scale for the ten patients who could be re-assessed was done. Results are satisfactory (very good or good) for 9 patients and bad for only one patient. On x-ray evaluation, 7 patients out of the ten, showed acetabular erosion.  Keywords: Benin; hip; Moore prosthesis; results

Electrical parameters for bifacial silicon solar cell study in modelling: capacitance and space charge region width determination

No Abstract Available Journal des Sciences pour l\'Ingenieur Vol 5 2005: 34-3

An empirical evaluation of GPGPU performance models

Computing systems today rely on massively parallel and heterogeneous architectures to promise very high peak performance. Yet most applications only achieve small fractions of this performance. While both programmers and architects have clear opinions about the causes of this performance gap, finding and quantifying the real problems remains a topic for performance modeling tools. In this paper, we sketch the landscape of modern GPUs’ performance limiters and optimization opportunities, and dive into details on modeling attempts for GPU-based systems. We highlight the specific features of the relevant contributions in this field, along with the optimization and design spaces they explore. We further use a typical kernel example (tiled dense matrix multiplication) to assess the efficacy and usability of a set of promising approaches. We conclude that the available GPU performance modeling solutions are very sensitive to applications and platform changes, and require significant efforts for tuning and calibration when new analyses are required