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Load Factor (load + factor)

Distribution by Scientific Domains

Engineering	71%

Selected Abstracts

Power flow congestion relief by using customer-side energy storage systems

ELECTRICAL ENGINEERING IN JAPAN, Issue 1 2007
Ken Furusawa
Abstract In recent years, energy storage systems have increasingly been expected as a means of load leveling of the annual load factor. Of course there is an effect of installing the energy storage systems at the substation. But some customers operate their storage system in an integrated way and it also has an effect of increasing the load factor. In this paper the authors proposed that the energy storage systems on the customer side be used for congestion relief on transmission networks. However, it is not clear which kind of customer has the effect of relieving transmission line congestion. First, this paper assumes the authors determine the optimal configuration of energy equipment including energy storage systems. We propose a new contract whereby electric utility subsidizes a part of the entrance cost of the energy storage systems and customers change the output pattern of energy storage according to the request of the electric utility. This paper evaluates the possibility that the contract gives merit to both the electric utility and the customer. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(1): 36,45, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20299 [source]

Collapse load factor of planar frames using a modified genetic algorithm

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 12 2004
A. Kaveh
Abstract In this article an analytical method is developed for identifying basic collapse mechanisms of rigid-jointed two-dimensional frames. In this approach, the deformation of each member is completely defined by four translations and one rotation. The behaviour of such an element lies in between that of a truss element and a flexural one. Once the basic collapse mechanisms are identified, the genetic algorithm is used to identify the mechanism corresponding to the least possible load factor. Examples are included to illustrate the efficiency of the present method compared to the use of a simple genetic algorithm. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Upper and lower bounds in limit analysis: Adaptive meshing strategies and discontinuous loading

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2009
J. J. Muñoz
Abstract Upper and lower bounds of the collapse load factor are here obtained as the optimum values of two discrete constrained optimization problems. The membership constraints for Von Mises and Mohr,Coulomb plasticity criteria are written as a set of quadratic constraints, which permits one to solve the optimization problem using specific algorithms for Second-Order Conic Program (SOCP). From the stress field at the lower bound and the velocities at the upper bound, we construct a novel error estimate based on elemental and edge contributions to the bound gap. These contributions are employed in an adaptive remeshing strategy that is able to reproduce fan-type mesh patterns around points with discontinuous surface loading. The solution of this type of problems is analysed in detail, and from this study some additional meshing strategies are also described. We particularise the resulting formulation and strategies to two-dimensional problems in plane strain and we demonstrate the effectiveness of the method with a set of numerical examples extracted from the literature. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Modelling aviation fuel demand: the case of the United States and China

OPEC ENERGY REVIEW, Issue 4 2008
Dr. Mohammad Mazraati
The aviation sector's contribution to the world economy is 8 per cent, while using 5.8 per cent of total world oil demand. Within the transportation sector, aviation consumes about 12.7 per cent of the total oil demanded by the transportation sector, with a growth rate of 2.32 per cent per annum in recent years, confirming the importance of aviation in the future energy market and economy. This paper considers modelling fuel demand in aviation sectors of two different markets. Jet fuel demand is modelled in the United States as a matured market and China as a fast growing market. A constant elasticity log-log model using recent data of passenger aviation traffic, freight aviation traffic and airline load factors for both countries. Economic growth and fuel prices were also considered as determinants in the model. A system of three equations was developed for each country to forecast long-term jet fuel consumption levels to 2025. The mature US aviation sector was found to react better to price and short-term economic fluctuations, in contrast with the fast growing Chinese aviation sector, where the hike in prices did not seem to have much effect. [source]

Quantitative exposure-response relations between physical workload and prevalence of lateral epicondylitis in a working population

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 6 2009
Z. Joyce Fan PhD
Abstract Background Lateral epicondylitis is a common work-related musculoskeletal disorder. The objective of this study was to identify risk factors associated with lateral epicondylitis among active workers. Methods Seven-hundred thirty-three workers in 12 Washington worksites participated in structured interviews, physical examinations, and individual exposure assessments of biomechanical and psychosocial factors. Multivariable logistic modeling was used. Results Thirty-eight subjects (5.2%) had lateral epicondylitis. Age (36,50 years-old), being female, and low social support at work were significant risk factors. Frequency of forceful exertion (,5 vs. <1 times/min (OR 5.17, 95%CI 1.78,15.02), and ,1 to <5 vs. <1 (OR 4.47, 95%CI 1.57,13.71)) and forearm supination at ,45° for ,5% of the time with high lifting force (OR,=,2.98, 95% CI 1.18,7.55) were significant physical load factors. Conclusions Frequency of forceful exertion or a combination of forearm supination and forceful lifting were significant physical factors and should be considered for prevention strategies. Am. J. Ind. Med. 52:479,490, 2009. © 2009 Wiley-Liss, Inc. [source]