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Circular Cross-section (circular + cross-section)

Distribution by Scientific Domains

Engineering	50%
Polymers and Materials Science	33%

Selected Abstracts

Numerical solution of eddy current problems in ferromagnetic bodies travelling in a transverse magnetic field

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2003
W. Peterson
Abstract Eddy currents are investigated in a ferromagnetic bar travelling in a transverse magnetic field. Such an open boundary field problem is analysed by a hybrid approach based on Galerkin finite element formulation coupled with a separation of variables. A steady state is considered, introducing time-periodic boundary conditions. The resultant system of non-linear equations is solved by an iterative procedure based on Brouwer's fixed-point theorem. Numerical results are presented for a bar of circular cross-section made of cast steel or cast iron. Selected examples of the field distribution and characteristics of eddy-current power losses are enclosed in graphic form. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Changes in Bone Density During Childhood and Adolescence: An Approach Based on Bone's Biological Organization

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2001
Frank Rauch
Abstract Bone densitometry has great potential to improve our understanding of bone development. However, densitometric data in children rarely are interpreted in light of the biological processes they reflect. To strengthen the link between bone densitometry and the physiology of bone development, we review the literature on physiological mechanisms and structural changes determining bone mineral density (BMD). BMD (defined as mass of mineral per unit volume) is analyzed in three levels: in bone material (BMDmaterial), in a bone's trabecular and cortical tissue compartments (BMDcompartment), and in the entire bone (BMDtotal). BMDmaterial of the femoral midshaft cortex decreases after birth to a nadir in the first year of life and thereafter increases. In iliac trabecular bone, BMDmaterial also increases from infancy to adulthood, reflecting the decrease in bone turnover. BMDmaterial cannot be determined with current noninvasive techniques because of insufficient spatial resolution. BMDcompartment of the femoral midshaft cortex decreases in the first months after birth followed by a rapid increase during the next 2 years and slower changes thereafter, reflecting changes in both relative bone volume and BMDmaterial. Trabecular BMDcompartment increases in vertebral bodies but not at the distal radius. Quantitative computed tomography (QCT) allows for the determination of both trabecular and cortical BMDcompartment, whereas projectional techniques such as dual-energy X-ray absorptiometry (DXA) can be used only to assess cortical BMDcompartment of long bone diaphyses. BMDtotal of long bones decreases by about 30% in the first months after birth, reflecting a redistribution of bone tissue from the endocortical to the periosteal surface. In children of school age and in adolescents, changes in BMDtotal are site-specific. There is a marked rise in BMDtotal at locations where relative cortical area increases (metacarpal bones, phalanges, and forearm), but little change at the femoral neck and midshaft. BMDtotal can be measured by QCT at any site of the skeleton, regardless of bone shape. DXA allows the estimation of BMDtotal at skeletal sites, which have an approximately circular cross-section. The system presented here may help to interpret densitometric results in growing subjects on a physiological basis. [source]

Design of forming shoulders with complex cross-sections

PACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2005
C. J. McPherson
Abstract Vertical ,form, fill and seal' machines are used to produce bags for packing particulate or multiple objects. In operation, film is drawn over a forming shoulder and the good design of the surfaces of the shoulder is vital to the successful operation. This paper reviews underlying geometrical definition for the shoulder, corresponding to a filling tube with circular cross-section. In practice, such cross-sections occur frequently, but other variant shapes are becoming increasingly common. A method is discussed and demonstrated for extending the approach to allow tubes formed from circular arcs and straight line segments to be handled. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Gel-spun polyacrylonitrile fiber from pregelled spinning solution

POLYMER ENGINEERING & SCIENCE, Issue 7 2010
Lianjiang Tan
Polyacrylonitrile (PAN) fibers have been gel spun from pregelled PAN spinning solution. The pregelled solution had network structure with elevated spinnability, the as-spun fiber from which had more circular cross-section and reduced skin-core difference. Drawing was more effective in inducing the segmental orientation and crystallization in gel-spun fiber than in dry,wet spun fiber. The mechanical properties of the gel-spun fiber were better than those of the dry,wet spun fiber after multi-stage drawing. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers [source]

Rotational motion of a discretized buckled beam

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2006
H. Troger
We study a simple discretized model of a vertical cylindrical beam with circular cross-section which is clamped at its lower end and free at its upper end. If the beam is longer than a critical length the initially straight configuration will loose its stability and the beam will buckle due to its own weight. Now the base of the buckled beam is rotated about its vertical axis. Several different families of steady state motions are detected for the undamped system. Their stability is investigated. Moreover it is shown that there is a big difference in the behavior of the discretized model of the beam whether internal damping is included in the model or not. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Silk Fibers Extruded Artificially from Aqueous Solutions of Regenerated Bombyx mori Silk Fibroin are Tougher than their Natural Counterparts

ADVANCED MATERIALS, Issue 3 2009
Guanqiang Zhou
Regenerated silk fibers extruded from fibroin solutions are highly lustrous and have uniform diameters and circular cross-sections. They are stronger, more extensible, and tougher than natural silkworm silk. These fibers can be spun under clean, sterile, and carefully regulated conditions, and may permit direct incorporation of drugs for controlled release, being suitable for biomedical applications. [source]