为孩子们工作

<正>在不影响紧邻的旧医院运行的前提下建造墨尔本皇家儿童医院,对工地上的8台塔式起重机是一个特殊的挑战。     

Root-metaphors for understanding: A framework for teachers and teacher educators of information and communication technologies

This paper argues for understanding ICT from the standpoint of philosophical world views. We present a framework, based on Pepper’s root-metaphors (Formism, Contextualism, Mechanism, Organicism, and Animism/Mysticism) and we illustrate the use of the framework by looking at a common example of ICT: e-mail. It is argued that such a framework is potentially helpful to ICT teachers, especially when they work with pre-service education students who are struggling with how to integrate ICT critically into their future classrooms.     

The importance of generalizability for anomaly detection

In security-related areas there is concern over novel “zero-day” attacks that penetrate system defenses and wreak havoc. The best methods for countering these threats are recognizing “nonself” as in an Artificial Immune System or recognizing “self” through clustering. For either case, the concern remains that something that appears similar to self could be missed. Given this situation, one could incorrectly assume that a preference for a tighter fit to self over generalizability is important for false positive reduction in this type of learning problem. This article confirms that in anomaly detection as in other forms of classification a tight fit, although important, does not supersede model generality. This is shown using three systems each with a different geometric bias in the decision space. The first two use spherical and ellipsoid clusters with a k-means algorithm modified to work on the one-class/blind classification problem. The third is based on wrapping the self points with a multidimensional convex hull (polytope) algorithm capable of learning disjunctive concepts via a thresholding constant. All three of these algorithms are tested using the Voting dataset from the UCI Machine Learning Repository, the MIT Lincoln Labs intrusion detection dataset, and the lossy-compressed steganalysis domain. Gilbert “Bert” Peterson is an Assistant Professor of Computer Engineering at the Air Force Institute of Technology. Dr. Peterson received a BS degree in Architecture, and an M.S. and Ph.D. in Computer Science at the University of Texas at Arlington. He teaches and conducts research in digital forensics and artificial intelligence. Brent McBride is a Communications and Information Systems officer in the United States Air Force. He received a B.S. in Computer Science from Brigham Young University and an M.S. in Computer Science from the Air Force Institute of Technology. He currently serves as Senior Software Engineer at the Air Force Wargaming Institute.     

Upgrading of bio-oil: Effect of light aldehydes on acetic acid removal via esterification

Since fast pyrolysis derived bio-oils are not a simple hydrocarbon mixture, but rather contain a variety of oxygenated compounds including acids and aldehydes, upgrading is required in order to use bio-oils as transportation fuels. Esterification is one of the attractive routes to convert acids contained in bio-oil to more desirable esters. Although organic acid esterification is a simple reaction, no work has been reported as to whether the presence of other reactive oxygenated compounds such as aldehydes affect the reaction. In this study of bio-oil model compounds, the impact of acetaldehyde and propionaldehyde on acetic acid esterification was investigated on organic–inorganic mesoporous silica functionalized with propylsulfonic acid groups. No impact of these two aldehydes on acetic acid consumption was seen at 100 °C, regardless of the concentration of ethanol used. However, at 70 °C and 50 °C, the conversion of acetic acid was observed to be lowered during the reaction in the presence of the aldehydes. When either of the aldehydes were present, the acetic acid conversion was about 6% and 28% lower than that in its absence at 70 °C and 50 °C, respectively. It appears that the more significant aldehyde impact on acetic acid conversion seen at the lower reaction temperatures was due to the esterification rate being slow relative to the rapid competitive acetalization rate of the aldehydes with ethanol.     

Crystal slip modeling of small strain yield behavior in textured copper tubing

A self-consistent polycrystalline model developed by Kr?ner, and Budiansky and Wu (KBW) was used to model small strain (2 and 8 × 10_-6) biaxial yield behavior in textured copper tubing. The results were compared to simulations using the Bishop-Hill model and a lower bound (LB) model which neglected strain compatibility. It was found that the Bishop-Hill model poorly represents texture effects whereas the KBW and LB models give accurate predictions of biaxial yield surfaces at these strain levels. A linear latent hardening law was used with both the KBW and LB model. Varying the latent hardening ratio an order of magnitude had little effect on the yield surface. Introducing the odd 1 coefficients of the generalized spherical harmonic expansion was also found to have negligible effect on the predicted yield loci. Formerly Graduate Student of Mechanical Engineering at Brigham Young University Formerly Graduate Student of Materials Science and Engineering at the University of Florida     

On a class of pseudo‐logarithmic amplifiers suitable for use with digitally switched resistors

This paper describes three circuits that implement pseudo‐logarithmic functions, which are simple and easy to implement. The circuits can be realized using operational amplifiers or current feedback amplifiers. Tuning can be achieved using switched resistors, or active resistors, or tunable transconductors, but are best suited for use with digitally switched resistors. Frequency response and stability considerations for two of the circuits are thoroughly discussed and PSPICE results confirming the theoretical results are presented alongside measured results. Copyright © 2007 John Wiley & Sons, Ltd.     

The ultrapurification of tellurium

High-purity tellurium is used in the preparation of II–VI compounds, particularly CdTe and Cd_x Hg_1?x Te. Distillation of tellurium under low-pressure H₂ reduces the concentrations of iron and silicon. The addition of CdTe to tellurium prior to zone refining, in a quantity less than the eutectic concentration, has been observed to change the segregation behavior of Ca, K, Ga and As, which enables more efficient refining. Emission spectroscopy, spark source mass spectroscopy and the evaluation of Cd_0.21Hg_0.79 Te have been used to characterize these effects.     

Development of orientation coherence in plane-strain deformation

Spatial orientation coherence in 20 pct channel-die compressed aluminum ingot is investigated using the two-point orientation coherence function (OCF) constructed from individual crystallite orientation measurements. It is found that orientation coherence clusters formed in the initially coherence-free ingot during deformation. The orientation coherence cluster consists of a central grain with lattice orientation (φ₁, ϕ, φ₂) surrounded by grains with lattice orientation (π + φ₁, ϕ, φ₂); this coincides with one of the processing-symmetry orientations of the central grain. The observed clustering is compared with simulations of structure evolution based upon the classical full-constraint Taylor model. As is expected, no coherence structure develops in these simulations. A mechanism of formation for the orientation coherence cluster is proposed based upon a requirement of stress equilibrium between neighboring grains, while maintaining, on average, strain compatibility with the overall plane-strain compression deformation mode. A simplified Fourier representation of the conditional two-point OCF is described, and a numerical scheme to obtain the expansion coefficients is proposed and tested. Formerly Visiting Scholar, Department of Mechanical Engineering, Brigham Young University, Provo, UT 84602, is retired.     

Culturally sensitive assertiveness training for ethnic minority clients.

This article serves as a comprehensive resource to help bridge the gap of cultural understanding for those using assertiveness training with ethnic minority clients. Therapists providing cross-cultural assertiveness training must be certain that gaining such skills is a value shared by the client and not imposed by the therapist. A more culturally appropriate approach includes the following general assessment strategies: determining the etiology of the lack of assertiveness; using self-report inventories that avoid words, slang, or situations that may not be meaningful to the client; and the developing norms for the cultural group for which the inventory will be used. General treatment strategies may include "message matching," backup assertion, and discriminative cue learning. Specific strategies that are relevant for each cultural group are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Removal of Phorbol Ester from Jatropha Seedcake Using Ozonation and Solar Irradiation

Jatropha curcas is a well-known source of non-edible vegetable oil that is being promoted as an energy source and high quality feedstock in biodiesel production, especially in developing countries. The potential that the resulting seedcake by-product from jatropha oil extraction (?70% by volume) could also be used as a component in animal feed raises the prospect that a commercially viable jatropha-based industry could be developed. To date, however, the use of jatropha seedcake in livestock feed formulation has been constrained by the presence of phorbol esters (PE), which are known promutagenic and toxic compounds, and by the inability to eliminate PE by cost-effective means. Using seedcake by-product collected from a commercial facility in West Africa that processes jatropha biodiesel, this study demonstrates cost-effective measures of eliminating PE from jatropha seedcake using a combination of solar irradiation and ozonation.