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Cross-sectional Shapes (cross-sectional + shape)
Selected AbstractsProcesses and mechanisms of dynamic channel adjustment to delta progradation: the case of the mouth channel of the Yellow River, ChinaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2003Changxing Shi Abstract This paper analyses the processes and mechanisms of a three-stage channel adjustment over a cycle of the Yellow River mouth channel extension based on data comprising hydrologic measurements and channel geometric surveys. Rapid siltation in the mouth channel takes place in the young stage when the channel is being built by deposits and in the old stage when the channel cannot further adjust itself to keep sediment transport in equilibrium. It is disclosed that the bankfull width,depth ratio, bed material size and slope decrease in the young and mature stages but do not change in the old stage. The reduction of bankfull width,depth ratio and bed material size during the young and mature stages is found to be able to offset the effect of the slope reduction on sediment transport due to continuous mouth progradation. They reach their limits in old stage, and a constant slope is kept by unceasing sediment accumulation. The grain size composition of incoming sediment and the fining mechanism are responsible for the occurrence of lower limit of bed material size. The reason for the existence of a limit of bankfull cross-sectional shape is that the large flows can fully transport the sediment load they are carrying, and siltation in the channel in the old stage takes place mainly in the low flows. It is suggested that the bankfull discharge plays an important role in shaping the channel but that the entire channel form is the product of both the large and low flows plus the effects of interaction between them. Channel pattern change shows a process from a braided pattern in the young stage to a straight pattern in the mature and old stages, and the straight channel becomes gradually sinuous. The occurrence and transformation of the channel patterns are supported by two planform predictors, but are also facilitated by some other conditions. Copyright © 2003 John Wiley & Sons, Ltd. [source] Novel mechanism for hair shine with special optical enhancement effect on blonde hairINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2010S. Iwai J. Cosmet. Sci., 60, 323,336 (May/June 2009) Accepted for publication October 21, 2008. Synopsis Compared with dark or brunette hair, blonde hair has different characteristic features of appearance such as bright shine with a soft tonal color. In this report, novel optical mechanisms of the characteristic blonde hair appearance are reported. Optical analyses of goniophotometric measurements were carried out to elucidate the mechanisms of strong reflections observed in blonde hairs. As a result, reflections with much higher intensity than those from the front surface of a fiber were confirmed to play important roles in the case of blonde hair fibers, and the intensities were found to vary with the cross-sectional shape of a fiber, the ellipticity (=minor axis/major axis). From light path simulation analyses, these strong reflections were verified to result from total reflection from the back surface of a fiber. Furthermore, since each hair fiber acts as a lens and/or a reflector, intricate reflection behaviors are suggested to occur as a consequence of the combination of light condensation and total reflection. [source] Evolution of the spermatozoon in muroid rodentsJOURNAL OF MORPHOLOGY, Issue 3 2005William G. Breed Abstract In the rodent superfamily Muroidea, a model for the evolution of sperm form has been proposed in which it is suggested that a hook-shaped sperm head and long tail evolved from a more simple, nonhooked head and short tail in several different subfamilies. To test this model the shape of the sperm head, with particular emphasis on its apical region, and length of sperm tail were matched to a recent phylogeny based on the nucleotide sequence of several protein-coding nuclear genes from 3 families and 10 subfamilies of muroid rodents. Data from the two other myomorph superfamilies, the Dipodoidea and kangaroo rats in the Geomyoidea, were used for an outgroup comparison. In most species in all 10 muroid subfamilies, apart from in the Murinae, the sperm head has a long rostral hook largely composed of acrosomal material, although its length and cross-sectional shape vary across the various subfamilies. Nevertheless, in a few species of various lineages a very different sperm morphology occurs in which an apical hook is lacking. In the outgroups the three species of dipodid rodents have a sperm head that lacks a hook, whereas in the heteromyids an acrosome-containing apical hook is present. It is concluded that, as the hook-shaped sperm head and long sperm tail occur across the muroid subfamilies, as well as in the heteromyid rodents, it is likely to be the ancestral condition within each of the subfamilies with the various forms of nonhooked sperm heads, that are sometimes associated with short tails, being highly derived states. These findings thus argue against a repeated evolution in various muroid lineages of a complex, hook-shaped sperm head and long sperm tail from a more simple, nonhooked sperm head and short tail. An alternative proposal for the evolution of sperm form within the Muroidea is presented in the light of these data. J. Morphol. © 2005 Wiley- Liss, Inc. [source] Statistical descriptions of channel networks and their shapes on non-vegetated hillslopes in Kemmerer, WyomingHYDROLOGICAL PROCESSES, Issue 10 2003D. A. Raff Abstract Erosion prediction tools are essential for many different aspects of land management. In this paper we examine the applicability of scaling relationships developed for river networks for the description of hillslope erosion channel networks. Eight erosion channel networks were studied on mine spoil sites in Kemmerer, Wyoming. We analysed these networks using well-known geomorphological relationships such as Horton's laws and Melton's law. An analysis of the erosion channel hydraulic geometry described by a series of power functions was also conducted. We found that the network geometry resembles larger river networks, and that the cross-sectional shapes of individual erosion channels exhibit statistical characteristics of their larger river counterparts. Copyright © 2003 John Wiley & Sons, Ltd. [source] Phase transformation behaviour and bending properties of hybrid nickel,titanium rotary endodontic instrumentsINTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2007Y. Hayashi Abstract Aim, To investigate the bending properties of hybrid rotary nickel,titanium endodontic instruments in relation to their transformation behaviour. Methodology, Four types of nickel,titanium rotary endodontic instruments with different cross-sectional shapes (triangular-based and rectangular-based) and different heat treatment conditions (super-elastic type and hybrid type with shape memory effect) were selected to investigate bending properties and phase transformation behaviour. Bending load of the instruments was measured in a cantilever-bending test at 37 °C with the maximum deflection of 3.0 mm. A commercial rotary instrument, ProFile (PF; Dentsply Maillefer, Ballaigues, Switzerland) was used as a reference for the bending test. Phase transformation temperatures were calculated from the diagrams obtained from differential scanning calorimetry. Data were analysed by anova and Scheffe's test. Results, The bending load values of the hybrid type that had undergone additional heat treatment at the tip were significantly lower (P < 0.05) than those of the super-elastic type with no additional heat treatment. The bending load values of rectangular-based cross-sectional shaped instruments were significantly lower (P < 0.05) than those of triangular-based cross-sectional shaped instruments. Phase transformation temperatures (Ms and Af points) of the hybrid type were significantly higher (P < 0.05) than the super-elastic type. The Mf and As points of the tip part were significantly higher (P < 0.05) than those of the whole part of the hybrid instrument. Conclusions, Additional heat treatment of hybrid nickel,titanium instruments may be effective in increasing the flexibility of nickel,titanium rotary instruments. [source] Fabrication of Bioinspired Actuated Nanostructures with Arbitrary Geometry and StiffnessADVANCED MATERIALS, Issue 4 2009Boaz Pokroy Bio-inspired, multifunctional, high-aspect-ratio nanostructured surfaces are fabricated in a variety of materials with controlled geometry and stiffness. A soft-lithography method that allows the one-to-one replication of nanostructures and renders it possible to produce arbitrary nanostructures with cross-sectional shapes, orientations, and 2D lattices that are different from the original master is presented. The actuation of the posts is demonstrated. [source] Random discontinuous carbon fiber preforms: Experimental permeability characterization and local modelingPOLYMER COMPOSITES, Issue 4 2010A. Endruweit Injection experiments indicate that for random discontinuous carbon fiber preforms, increasingly uneven flow fronts develop with increasing fiber bundle length and filament count. While at high propensity for fiber bundle splitting, the preform permeability increases continuously with increasing fiber length, no trend can be identified at low propensity. No clear influence of the virgin bundle filament count on the preform permeability was observed. Types of sizing used on the fibers and bundle cross-sectional shapes may vary and affect the intrinsic filamentization behavior, thus dominating the preform permeability. In a model for local preform permeability, interbundle voids, distributed randomly across the preform thickness, are approximated via a regular void structure. Simulated filling patterns are qualitatively similar to those observed experimentally, showing more pronounced features than those derived from a model based on local through-thickness homogenization of the filament distribution. A model based on an alternating arrangement of fiber bundles and voids allows prediction of global preform permeability values from series of injection simulations, showing quantitatively better agreement with corresponding experimental results than the homogenization model. For global permeability, agreement between simulated and experimental mean values improves with increasing fiber volume fraction, whereas calculated coefficients of variation show no strong dependence on the fiber volume fraction. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers [source] | |||||||||||||