Structural Modeling of Inflated Foam-Rigidized Aerospace Structures

An ideal aerospace structure would be inexpensive, a convenient size and weight for launch, easily deployed, and provide necessary stiffness∕performance. This paper examines one type of potentially inexpensive, easily deployed space structure: the inflated foam-rigidized structure. Research aimed at gaining insight into the construction and structural characteristics of foam-rigidized inflated aerospace structures is presented in this paper. Sample foam-rigidized struts were fabricated using a two-part commercially available closed-cell polyurethane foam that was injected in a controlled fashion into a cylindrical Kapton shell. These struts were tested nondestructively to evaluate bending behavior and destructively to examine material characteristics. Testing of the foam-rigidized struts indicates that significant variations of material properties should be expected when injecting polyurethane foam into a single spot and allowing it to expand to fill a structure. An analytical model of the bending behavior of foam-rigidized inflated struts is also presented and compared with experimental bending data.     

Microstructure-mechanical property relationships in isothermally transformed vanadium steels

The relationships between the interphase precipitation reaction and the mechanical properties of an Fe-0.2C-l.0V-0.5Mn steel were studied after isothermal transformation in the temperature range 600 °C to 750 °C. The strength and room temperature toughness of the transformed steel are found to be determined by the austenitization temperature, vanadium carbide solubility, volume fraction of VC available for precipitation, size of the precipitates, and ferrite grain size. Yield strength increments due to precipitation are predicted by Melander’s model for critical resolved shear stress, when all the available carbide precipitated as interphase VC. For lower austenitization temperatures, yield strength increments are modeled by a bimodal distribution of undissolved and interphase (or matrix) precipitates. Six classifications of VC morphologies are identified in the transformed microstructures, but one of these, the “fibrous” VC morphology, could not be associated with degradation of toughness as suggested by Mishima. The impact transition temperatures are approximated by regression analyses for bainitic steels. The results show that both strength and toughness can be simultaneously optimized in this steel and suggest that microstructures with strength and toughness levels equivalent to those of quenched and tempered steels can be produced in vanadium steels by thedirect decomposition of austenite.     

Effect of Processing on Release from an Inert, Heterogeneous Matrix

Matrixes containing 40% ephedrine hydrochloride and hydrogenated castor oil are prepared by two processes: (a) compression of a physical mixture and (b) compression of a congealed melt. The release from the melt matrix is slower than from the matrix prepared by compression of a physical mixture. applied pressure on the release profile is studied. For matrixes prepared by both processes as the applied pressure is increased, the release rate is slower; however, this effect is more pronounced for the physical mixture matrix. The effect of comminution of the medicinal compound on release profile is considered. mixture the fastest release occurs from the finer particles suggesting a boundary layer diffusion. In matrixes produced by the melt process as the particle size is decreased, the release is slowed presumably because of an increased tortuosity and more intimate contact between the ephedrine hydrochloride and the hydrogenated castor oil, which produces mass transfer by matrix diffusion.     

Group size and social interactions are associated with calling behavior in Carolina chickadees (Poecile carolinensis).

The complexity of a social group may influence the vocal behavior of group members. Recent evidence in Carolina chickadees, Poecile carolinensis, indicated that one component of social complexity, group size, influenced the complexity of the "chick-a-dee" call, a vocalization functioning in social cohesion. Individuals in larger social groups used calls with greater information than did individuals in smaller social groups. Here, the authors review this earlier work, and describe a recent study indicating that social interactions between females and males within female-male pairs of chickadees were associated with rates of chick-a-dee call production in the males. Together, these studies suggest that the nature and complexity of social interactions among members of chickadee social groups influence chick-a-dee calling behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perception of three-dimensional form from patterns of optical texture.

Investigated how patterns of optical texture provide information about the three-dimensional structure of objects in space. Four experiments were performed in which observers were asked to judge the perceived depth of simulated ellipsoid surfaces under a variety of experimental conditions. Results show that (a) judged depth increases linearly with simulated depth although the slope of this relation varies significantly among different types of texture patterns. (b) Random variations in the sizes and shapes of individual surface elements have no detectable effect on observers' judgments. (c) The perception of three-dimensional form is quite strong for surfaces displayed under parallel projection, but the amount of apparent depth is slightly less than for identical surfaces displayed under polar projection. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterisation of Conform? and conventionally extruded Al–4Mg–1Zr. Effect of extrusion route on superplasticity

Continuous extrusion (Conform™) is a well-established technique for the production of profiles from both solid and particulate feed stock. To the first approximation it is considered to be analogous to conventional extrusion, although there are significant differences in the metal flow during both processes. Metal flow during conventional extrusion is characterised by relatively low redundant work, whereas the Conform™ process requires significant redundant work to be successful. Most of the available scientific literature to date is concerned with the simulation of the Conform™ process and not its effect on the resultant microstructure of the product. In this paper, a detailed comparison of the microstructure, texture and superplastic properties developed during Conform™ and conventional extrusion for a particulate Al–4Mg–1Zr alloy are presented.     

化解数字视频的技术障碍

针对安全监控系统而言,主要任务就是需要一种低成本方式,实现在几小时、几天、几周乃至几个月的时间里实现视频影像的传输、存储以及搜索.就此,随着关键技术的不断发展,安全监控行业正经历着重大技术提升.     

Drawing on clinical practice to inform research on child and adolescent psychotherapy: Survey of practitioners.

This study was designed to draw on clinical practice as a way of identifying priority areas for child and adolescent psychotherapy research. 1,162 psychologists and psychiatrists described several features of their clinical work and evaluated the effects of alternative treatment approaches, factors that influence therapeutic change, and the priority of alternative types of research. The majority agreed on (a) the importance of several specific child, parent, and therapist factors that contribute to outcome; (b) the utility and effectiveness of alternative treatment approaches; and (c) the high priority of research on therapeutic processes and matching cases to alternative types of treatments. In general, the factors, treatments, and types of studies identified have rarely been examined empirically. The use of practitioner views to identify lines of research may aid not only in reducing the hiatus between research and practice but also in placing clinical work on a stronger empirical footing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predicting educational attainment, occupational achievement, intellectual skill, and personal adjustment among gifted men and women.

The cognitive potential of many gifted children goes unfulfilled. This study was designed to isolate factors, other than cognitive skill, that might predict adult achievements and personal adjustment among the gifted. Subjects were 1,069 gifted men (n?=?595) and women (n?=?474) who have been followed for 60 years as part of the Terman Genetic Studies of Genius. Childhood personality traits, parental education, and early home environment variables were examined as predictors of educational and occupational achievement among adults. The final model depicted five longitudinal relationships that predicted educational attainment, intellectual skill, and personal adjustment among both men and women. Two additional paths explained occupational achievement. The implications of this final model are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)