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Object Characteristics (object + characteristic)

Distribution by Scientific Domains

Engineering	50%

Selected Abstracts

The influence of impact object characteristics on impact force and force absorption by mouthguard material

DENTAL TRAUMATOLOGY, Issue 1 2004
Tomotaka Takeda
Abstract,,, Most impact force and impact energy absorption tests for mouthguards have used a steel ball in a drop-ball or the pendulum device. However, in reality most sports-related trauma is caused by objects other than the steel ball, e.g. various sized balls, hockey puck, or bat or stick. Also, the elasticity, the velocity and the mass of the object could change the degree and the extent of injuries. In this study, we attempted to measure the impact force from actual sports equipment in order to clarify the exact mechanism of dental-related sports injuries and the protective effects of mouthguards. The present study was conducted using the pendulum impact device and load cell. Impact objects were removable. Seven mobile impact objects were selected for testing: a steel ball, baseball, softball, field hockey ball, ice hockey puck, cricket ball, and wooden baseball bat. The mouthguard material used in this study was a 3-mm-thick Drufosoft (Dreve-Dentamid GmbH, Unna, Germany), and test samples were made of the one-layer type. The peak transmitted forces without mouthguard ranged from the smallest (ice hockey stick, 46.9 kgf) to the biggest (steel ball, 481.6 kgf). The peak transmitted forces were smaller when the mouthguard was attached than without it for all impact materials but the effect was significantly influenced by the object type. The steel ball showed the biggest (62.1%) absorption ability while the wooden bat showed the second biggest (38.3%). The other balls or the puck showed from 0.6 to 6.0% absorbency. These results show that it is important to test the effectiveness of mouthguards on specific types of sports equipment. In future, we may select different materials and mouthguard designs suitable for specific sports. [source]

Solving inverse electromagnetic problems using FDTD and gradient-based minimization

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2006
Erik Abenius
Abstract We address time-domain inverse electromagnetic scattering for determining unknown characteristics of an object from observations of the scattered field. Applications include non-destructive characterization of media and optimization of material properties, for example, the design of radar absorbing materials. Another application is model reduction where a detailed model of a complex geometry is reduced to a simplified model. The inverse problem is formulated as an optimal control problem where the cost function to be minimized is the difference between the estimated and observed fields, and the control parameters are the unknown object characteristics. The problem is solved in a deterministic gradient-based optimization algorithm using a parallel 2D FDTD scheme. Highly accurate analytical gradients are computed from the adjoint formulation. The inverse method is applied to the characterization of layered dispersive media and the determination of parameters in subcell models for thin sheets and narrow slots. Copyright © 2006 John Wiley & Sons, Ltd. [source]

The Effect of Clustering on Office Rents: Evidence from the Amsterdam Market

REAL ESTATE ECONOMICS, Issue 2 2009
Maarten G.J. Jennen
This article examines the rent effects of office clustering in the Amsterdam office market for the period 2000,2005. We isolate the rent effects of location density based on geographic information system (GIS) methodology, while controlling for variations in object characteristics in a cross-sectional hedonic model. While controlling for the age, location and quality of the object, we find a strong positive effect of being located in dense office areas. We find that the vicinity of other office objects is priced into rent levels, regardless of market conditions. This article extends existing literature by examining the influence of clustering outside the United States, during changing economic tides and by application of novel methodology, based on objective clustering schemes, which can be replicated for other geographic areas. [source]

A novel alternating current imaging radiometer for the security inspection

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2008
Guang-Feng Zhang
Abstract Different from the traditional direct current radiometric imaging, an alternating current (AC) radiometer was presented to be passive millimeter-wave imaging with simple and integrated structure for the purpose of security inspection in China. The AC radiometer image interpretation has its own characteristic. The imaging results of 3-mm waveband AC radiometer show that it can obtain concealed objects characteristic and can be used to inspect the passenger for antiterrorism. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 3259,3261, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23916 [source]