481,984 research outputs found
Power Calculations in R
No full textPower analysis is a statistical method used to determine the likelihood that a study will detect an effect of a specified size, given a particular sample size and significance level. By understanding the relationship between sample size, effect size, and significance level, researchers can design studies with sufficient statistical power to detect meaningful effects. This practical session serves as a primer on power calculations in R. We will discuss the core principles of power analysis, focusing on identifying what to power for (the main research question and effect size) and learning flexible rules for various types of power calculations. Participants will learn hands-on how to set up and run basic power analyses using the R programming language. Examples will be drawn from health science literature. For hierarchical, nested experimental designs without analytical power solutions, we’ll focus on simulation-based approaches. By the end of this session, participants will have a toolkit of methods for conducting accurate power analyses across different experimental frameworks, enabling them to design robust studies that are well-powered for their scientific goals
Is There Market Power in the French Comte Cheese Market?
No full textAn NEIO approach is used to measure seller market power in the French Comté cheese market, characterised by government-approved supply control. The estimation is performed on quarterly data at the wholesale stage over the period 1985-2005. Three different elasticity shifters are included in the demand specification, and the supply equation accounts for the existence of the European dairy quota policy. The market power estimate is small and statistically insignificant. Monopoly is rejected, as well as weak forms of Cournot oligopoly. Results appear to be robust to the choice of functional form, and suggest little effect of the supply control scheme on consumer prices.Supply control, NEIO, protected designation of origin, Marketing,
Len Power
No full text"F/O Len Power Pilot B25 2 Squadron Hughes Proud to have fought [Signature] L.E. Power."Flying Officer Len Power. Pilot B25. 2 Squadron, Hughes. Proud to have fought. [Signature] L.E. Power
Improved system operations with high penetration of wind power : a dialog between academia and industry - Ireland
No full textPanel session submission for the IEEE Power and Energy Society (PES) 2010 General Meeting, July 25-29 2010, Minneapolis, MinnesotaThis is a submission to a panel session at the 2010
IEEE PES General Meeting. It discusses effective collaboration
between academia and industry.Science Foundation IrelandConference websitehttp://ewh.ieee.org/conf/pesgm10/Charles Parsons Energy Research AwardsCharles Parso
Impact of wind power on the unit commitment, operating reserves and market design
No full textPaper presented at the 2011 IEEE Power and Energy Society General Meeting, San Diego, CA, 24-29 July 2011This article highlights and demonstrates the new requirements variable and partly unpredictable wind power will bring to unit commitment and power system operations.
Current practice is described and contrasted against the new requirements. Literature specifically addressing questions about wind power and unit commitment related power system operations is surveyed. The scope includes forecast errors, operating reserves, intra-day markets, and sharing reserves across interconnections. The discussion covers the critical issues arising from the research.Science Foundation Irelandau, ti, ke, ab, co - TS 10.04.1
Geothermal Power Generation as Related to Resource Requirements
No full textFor the past several years geothermal exploratory work has been conducted in northern Nevada. In conjunction with that effort a proposed 55-MW steam geothermal power plant was considered for initial installation in one of the fields being developed. The characteristics of the geothermal fields under consideration were not firm, with data indicating widely varying downhole temperatures. Thus, neither the resource nor the plant operating conditions could be set. To assist both the ultimate user of the resource, the utility, and the developer of the geothermal field, a series of parametric sensitivity studies were conducted for the initial evaluation of a field vis-a-vis the power plant. Using downhole temperature as the variable, the amount of brine, brine requirements/kWh, and pounds brine/pound of steam to the turbine were ascertained. This was done over a range of downhole temperatures of from 350F to 475F.
The studies illustrate the total interdependence of the geothermal resource and its associated power plant. The selection of geothermal steam power plant design conditions must be related to the field in which the plant is located. The results of the work have proven to be valuable in two major respects: (1) to determine the production required of a particular geothermal field to meet electrical generation output and (2) as field characteristics become firm, operating conditions can be defined for the associated power plant
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Transient stability sensitivity analysis of a simplified power system
No full textThere are many limits in power system operation however transient stability poses some of the most stringent limitations. Typical measures to assess transient stability, such as critical fault clearing time, provide some indication of whether or not a power system will remain stable after a large disturbance. However, these measures do not give any further insight into how system parameters should be regulated to ensure adequate system security. This paper explores the sensitivity of (a) power transfer-limits and (b) transient stability margins to variations in a number of system parameters for a single machine infinite bus system. Several alternative stability margins are considered
Multiple flashing in geothermal power plants
No full textGeothermal-based flash steam power plants are promising systems for clean power generation. A comprehensive thermodynamic analysis through energy and exergy approaches is presented here to investigate the optimum flashing pressures for multistep plants, including single-, double-, triple-, and quadruple-flash systems with reinjection. A new methodology is presented to investigate the optimum pressure levels for the flashing process, which can be considered as a suitable range of operation in power-generating geothermal plants. The present methodology is combined with a family of curves representing power output vs flashing pressure to determine the maximum available power for the system. The performances of the proposed systems are evaluated from both energy and exergy perspectives. It is shown that an energy efficiency analysis alone is insufficient to differentiate between the systems. The results of the exergy approach indicate a significant improvement in terms of efficiency as the quantity of flashing steps has risen. The potential performance enhancement in terms of power output becomes smaller as the quantity of flashing steps becomes four or more
Effects of power electronics devices on the energy quality of an administrative building
No full textThis paper proposes the analysis of the effects of power electronics devices
on the energy quality of an administrative building. For the study a method is
applied that allows the analysis of the main problems of energy quality such
as voltage variation, harmonics, flicker, and the effect of harmonics on the
power factor. As a case study, the offices of an administrative building were
used, where the measurements of the main energy quality parameters were
carried out for a week. The results showed the presence of current harmonics
and flicker problems due to non-linear loads such as the frequency inverters
that drive the motors of the elevators and escalators, as well as the LED
lamps. These problems cause systematic damage to the lighting system, UPS
and improper correction of the power factor. The study also demonstrates the
need to deepen the effects of energy quality not only in the industrial and
residential sectors. In addition, attention must be paid to the tertiary sector,
specifically to administrative buildings.Universidad de la Costa, Universidad de Cienfuegos, Universidad Autónoma de Occidente.Silva Ortega, Jorge IvanSousa Santos, VladimirSarmiento Crespo, Paulo CesarGómez Sarduy, Julio R.Viego Felipe, Percy R.Quispe, Enrique Cir
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