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Load Pattern (load + pattern)

Distribution by Scientific Domains
Engineering50%

Selected Abstracts

Dynamic characteristics of a PEM fuel cell system for individual houses

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 15 2006
S. ObaraArticle first published online: 1 AUG 200
Abstract The method of determination of the control variables for a system controller, which controls the electric power output of a solid-polymer-membrane (PEM) fuel cell system during electric power load fluctuations, was considered. The operation was clarified for the response characteristics of electric power generation for setting the control variables of proportional action and integral action considered to be the optimal for the system controller. The power load pattern of an individual house consists of loads usually moved up and down rapidly for a short time. Until now, there have been no examples showing the characteristics of the power generation efficiency of a system that follows a load pattern that moves up and down rapidly. Therefore, this paper investigates the relation of the control variables and power generation efficiency when adding change that simulates the load of a house to PEM fuel cell cogeneration. As a result, it was shown that an operation, minimally influenced by load fluctuations, can be performed by changing the control variables using the value of the electric power load of a system. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Pes planovalgus in RA: a descriptive and analytical study of foot function determined by gait analysis

MUSCULOSKELETAL CARE, Issue 1 2003
Deborah E. Turner BSc SRCh
Abstract Objective: To compare gait and foot function between rheumatoid arthritis (RA) patients with painful pes planovalgus deformity and healthy age- and sex-matched adults. Methods: Gait analysis was undertaken in 23 RA patients (14 female and 9 male, mean age 52.3 years, mean disease duration 6.6 years) and 23 healthy adults (14 female and 9 male, mean age 49.5 years). Gait measurements included temporal and spatial parameters, plantar pressures and three-dimensional (3D) kinematics at the ankle joint complex (AJC). The mean differences between the groups and associated confidence intervals were calculated using the t distribution. Results: RA patients showed longer gait cycle (mean difference 0.15 sec and 0.14 sec for right and left limbs, respectively) and double-limb support times (mean difference 8.3% and 7.9% for right and left limbs, respectively), shorter stride length (mean difference ,0.31 m for right and left limbs), slower walking speed (mean difference ,0.39 m/sec) and lower cadence (mean difference ,16.6 steps/min). In comparison with the normal group, RA patients had greater AJC dorsi/plantarflexion range of motion (ROM) (mean difference 5.7 °) and inversion/eversion ROM (mean difference 2.9 °). The frontal plane position of the AJC was more everted at specific stance periods (mean difference at heel strike ,2.4 ° and at midstance ,4.0°). Furthermore, both the peak eversion (mean difference ,4.1 °) and summated eversion motion as a function of time (mean difference ,313.9 °) were greater in the RA group. The pes planovalgus foot in RA was characterized by increases in peak pressure (mean difference 34.3 kPa), pressure,time integral (mean difference 18.2 kPa.sec), peak force (mean difference 1.7 N), force,time integral (mean difference 0.7 N.sec), contact time (mean difference 9.8% roll over process) and contact area (mean group difference 3.4 cm,2) in the medial midfoot. Further changes in the load pattern in the forefoot were observed in the RA patients, namely increases in the peak pressure (mean difference 96.4 kPa), pressure,time integral (mean difference 58.4 kPa.sec), and contact area (mean difference 1.7 cm,2) in the medial forefoot region and reduction in contact area (mean difference ,3.9 cm,2), peak force (mean difference ,7.2 N) and force,time integral (mean difference ,1.6 N.sec) in the lateral forefoot. Conclusions: Painful pes planovalgus deformity in RA is associated with global changes in gait, and localized structural and functional changes in the foot which can be accurately measured using clinical gait analysis. Copyright © 2003 Whurr Publishers Ltd. [source]

Identification of Modal Combinations for Nonlinear Static Analysis of Building Structures

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 4 2004
Sashi K. Kunnath
An increasingly popular analytical method to establish these demand values is a "pushover" analysis in which a model of the building structure is subjected to an invariant distribution of lateral forces. Although such an approach takes into consideration the redistribution of forces following yielding of sections, it does not incorporate the effects of varying dynamic characteristics during the inelastic response. Simple modal combination schemes are investigated in this article to indirectly account for higher mode effects. Because the modes that contribute to deformations may be different from the modes that contribute to forces, it is necessary to identify unique modal combinations that provide reliable estimates of both force and deformation demands. The proposed procedure is applied to typical moment frame buildings to assess the effectiveness of the methodology. It is shown that the envelope of demands obtained from a series of nonlinear static analysis using the proposed modal-combination-based lateral load patterns results in better estimation of inter-story drift, a critical parameter in seismic evaluation and design. [source]

Articular to diaphyseal proportions of human and great ape metatarsals

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010
Damiano Marchi
Abstract This study proposes a new way to use metatarsals to identify locomotor behavior of fossil hominins. Metatarsal head articular dimensions and diaphyseal strength in a sample of chimpanzees, gorillas, orangutans, and humans (n = 76) are used to explore the relationships of these parameters with different locomotor modes. Results show that ratios between metatarsal head articular proportions and diaphyseal strength of the hallucal and fifth metatarsal discriminate among extant great apes and humans based on their different locomotor modes. In particular, the hallucal and fifth metatarsal characteristics of humans are functionally related to the different ranges of motion and load patterns during stance phase in the forefoot of humans in bipedal locomotion. This method may be applicable to isolated fossil hominin metatarsals to provide new information relevant to debates regarding the evolution of human bipedal locomotion. The second to fourth metatarsals are not useful in distinguishing among hominoids. Further studies should concentrate on measuring other important qualitative and quantitative differences in the shape of the metatarsal head of hominoids that are not reflected in simple geometric reconstructions of the articulation, and gathering more forefoot kinematic data on great apes to better understand differences in range of motion and loading patterns of the metatarsals. Am J Phys Anthropol 143:198,207, 2010. © 2010 Wiley-Liss, Inc. [source]