Low temperature thermal conductivity of twinned and untwinned indium-thallium alloys

The low-temperature lattice thermal conductivity of twinned and untwinned, martensitic and non-martensitic, indium-thallium alloys has been measured to probe the effect of twin boundaries on phonon thermal transport. The phonon scattering by electrons, sample surfaces, dislocations, and thallium impurities is accounted for adequately by existing theoretical models. The reduced lattice thermal conductivity seen in twinned samples is attributed to additional phonon scattering by twin boundaries and, for the polycrystalline samples, by grain boundaries. Phonon scattering by twin boundaries is much weaker than that generally reported for grain boundaries, and is well represented by an acoustic-mismatch model.     

A new algorithm for shortest paths among obstacles in the plane

We introduce a new algorithm for computing Euclidean shortest paths in the plane in the presence of polygonal obstacles. In particular, for a given start points, we build a planar subdivision (ashortest path map) that supports efficient queries for shortest paths froms to any destination pointt. The worst-case time complexity of our algorithm isO(kn log² n), wheren is the number of vertices describing the polygonal obstacles, andk is a parameter we call the illumination depth of the obstacle space. Our algorithm usesO(n) space, avoiding the possibly quadratic space complexity of methods that rely on visibility graphs. The quantityk is frequently significantly smaller thann, especially in some of the cases in which the visibility graph has quadratic size. In particular,k is bounded above by the number of different obstacles that touch any shortest path froms.Partially supported by NSF Grants IRI-8710858 and ECSE-8857642 and by a grant from Hughes Research Laboratories, Malibu, CA.     

An automated vision based on-line novel percept detection method for a mobile robot

It is generally agreed that learning, either supervised or unsupervised, can provide the best possible specification of known classes and offer inference for outlier detection by a dissimilarity threshold from the nominal feature space. Novel percept detection can take a step further by investigating whether these outliers form new dense clusters in both the feature space and the image space. By defining a novel percept to be a pattern group that has not been seen before in the feature space and the image space, in this paper, a non-conventional approach is proposed for multiple-novel-percept detection problem in robotic applications. Based on a computer vision system inspired loosely by neurobiological evidence, our approach can work in near real time for highly sparse high-dimensional feature vectors extracted from image patches while maintaining robustness to image transformations. Experiments conducted in an indoor environment and an outdoor environment demonstrate the efficacy of our method.     

Radial distribution functions of non-crystalline polymers and their application to the structural analysis of PMMA

The use of Radial Distribution Functions (RDFs) in the determination of the structure of non-crystalline polymers is briefly reviewed. Particular aspects of the procedure for preparing RDFs from X-ray scattering are discussed in detail; namely the employment of an energy dispersive detector to remove the Compton component of the scattered X-rays and the application of the method of sampled transforms. A RDF is presented for atactic polymethylmethacrylate (PMMA) and its precision and reliability are discussed. It is analysed by comparison with RDFs calculated from computer-generated atom co-ordinates for isolated lengths of PMMA chains in different conformations. Methods are introduced by which the calculated RDFs are smeared to account for random disorder in the real chain and normalized so that, despite the finite range of the model, they can be immediately compared with the difference RDF which is directly obtained by transforming the data. Comparison between experimental and calculated RDFs shows that reasonable agreement is only obtained for a very limited range of conformations corresponding to sequences of backbone bond rotation angles of (10, 10, –10, –10) and the bond angles alternately 110 and 128. The form of the RDF appears very sensitive to important aspects of the molecular structure. The results both confirm and refine an earlier proposal from this laboratory which was based on comparisons between experimental and calculated functions in reciprocal space.     

用开关稳压控制器产生快速脉冲

模拟步进功能的快速上升沿脉冲源可以完成很多有用的实验室测量工作,包括确定同轴电缆上升时间特性,以及用时域反射方法找到电缆故障点。例如,在估算一个10英尺～20英尺长RG-58/U电缆的上升时间时,就需要1ns～2ns的边沿跃升时间。Agilent公司(www．agilent．com)的HP8012B是一个在很多电子实验室中都有使用的,可以承受大量工作负荷的脉冲发生器,它提供具有5 ns上升时间的脉冲,这足以用于许多应用场合,但不适合用于确定电缆特性。     

Alcohol's Effect on Triggered Displaced Aggression.

The authors examined alcohol's effect on triggered displaced aggression, the hostile reaction to a second provoking person after provocation from a first. Participants consumed an alcoholic or a nonalcoholic beverage. Subsequently, one individual provoked all of them with moderate intensity. Then, 2 groups were studied: those who received or who failed to receive a second provocation of minimal intensity. Consistent with prior research, participants who received a second, minimal provocation displayed more aggression than those who did not. After participants drank alcohol, the magnitude of this difference was significantly greater, indicating that alcohol increases triggered displaced aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance of Alcohol and Safer Sex Change Rulers Compared With Readiness to Change Questionnaires.

As part of a larger intervention study, the authors hypothesized that change rulers created for alcohol and safer sex would be equivalent to longer questionnaires. Ninety-six male college students completed rulers and questionnaires for assessing behavior change readiness. Participants' scores on the rulers significantly correlated with their scores on the questionnaires (r = .77 for alcohol; r = .77 for safer sex). In both domains, the rulers outperformed the questionnaires in predicting behavioral intentions, suggesting that the rulers had at least comparable concurrent criterion validity. This finding is the first of its kind in the safe sex literature and suggests that quick assessments of readiness to change are possible. Because the rulers are a continuous measure, the results are consistent with the idea that the change process is continuous rather than a series of discrete stages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A fuzzy median‐of‐intercept straight‐line algorithm for use in noisy images

Recently, a crisp robust median‐of‐intercept (MI) straight‐line fitting algorithm was devised for use in image‐processing applications. The algorithm is specifically designed for use in noisy images when the input data is corrupted with both noise and outliers. In this article we describe a fuzzy MI algorithm whose performance is significantly better than the original crisp algorithm. In addition, the new algorithm is fast; its computational complexity being only marginally greater than the original MI algorithm. © 2003 Wiley Periodicals, Inc.     

Product family modeling for mass customization

With growing reliance on modeling in product development, it is imperative to describe product families in a cohesive way. In particular, mass customization calls for a close integration of product life cycle from customer recognition to delivery and services. This paper proposes a triple-view scheme for modeling product families. Technical challenges are discussed by comparing product family modeling with modeling single products. Individual modeling formalisms for different views are discussed. An example of product family modeling in power supply design is presented to illustrate the feasibility and potential of the proposed approach.     

Childhood Peer Rejection and Aggression as Predictors of Adolescent Girls' Externalizing and Health Risk Behaviors: A 6-Year Longitudinal Study.

This 6-year longitudinal study examined girls' peer-nominated social preference and aggression in childhood as predictors of self- and parent-reported externalizing symptoms, substance use (i.e.. cigarette, alcohol, and marijuana use), and sexual risk behavior in adolescence. Participants were 148 girls from diverse ethnic backgrounds, who were initially assessed in Grades 4-6 and again in Grades 10-12. Results supported a moderator model, indicating that social preference changed the nature of the association between childhood aggression and adolescent outcomes. When accompanied by peer rejection, aggressive behavior was moderately stable over time and significantly associated with adolescent girls' substance use and sexual risk behavior. However, under conditions of peer acceptance, no significant association between childhood aggression and adolescent outcomes emerged. (PsycINFO Database Record (c) 2010 APA, all rights reserved)