Optimal design of water distribution networks by a discrete state transition algorithm

In this study it is demonstrated that, with respect to model formulation, the number of linear and nonlinear equations involved in water distribution networks can be reduced to the number of closed simple loops. Regarding the optimization technique, a discrete state transition algorithm (STA) is introduced to solve several cases of water distribution networks. Firstly, the focus is on a parametric study of the ‘restoration probability and risk probability’ in the dynamic STA. To deal effectively with head pressure constraints, the influence is then investigated of the penalty coefficient and search enforcement on the performance of the algorithm. Based on the experience gained from training the Two-Loop network problem, a discrete STA has successfully achieved the best known solutions for the Hanoi, triple Hanoi and New York network problems.     

Impaired timing precision produced by striatal D2 receptor overexpression is mediated by cognitive and motivational deficits.

Increased striatal dopamine D2 receptor activity is thought to contribute to the pathophysiology of schizophrenia. To model this condition in mice, Kellendonk et al. (2006) generated transgenic mice that selectively overexpress the D2 receptor in striatum (D2OE). Drew et al. (2007) reported that D2OE mice display deficits in interval timing and motivation. The present study further explored the impaired timing in D2OE mice. Experiment 1 assessed the role of motivation in producing timing deficits in the peak procedure and found that performance in D2OE mice was improved by increasing motivation. In addition, performance was impaired in control mice when motivation was decreased. In Experiment 2, we found that D2OE mice have no timing impairment when tested using the bisection task, a procedure in which the measure of timing performance is less influenced by motivation to respond. In Experiment 3, we also used the bisection task and found selective impairment in timing of long durations in D2OE mice. These results suggest that striatal D2 overexpression impairs timing by decreasing motivation and through its impact on working memory and/or sustained attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Protective relaying for multi-source generator buses

The reliability of an industrial power system can be increased by proper selection and application of protective relays. This is especially true for the medium-voltage distribution system. An effective protective relay application scheme is presented that uses devices widely used in present pulp and paper mill power distribution systems. The effective use of summation overcurrent and directional overcurrent relays for multisource generator buses makes it possible for the power system protective engineer to achieve good selective operation between source buses for both phase and ground fault current conditions. This greatly enhances the reliability of the power distribution system     

Computer Analysis of Impedance Effects in Large Grounding Systems

In large plants with high primary fault levels, the whole plant must be considered as forming the ground grid for the return of primary fault current. The internal impedance of the equivalent ground grid must be taken into account in grid potential rise calculations, as grid potentials transferred from one area of the plant may cause hazardous touch potentials at other locations. Field measurements and computer analyses to calculate the distribution of grid potential rise in a large grounding system are presented.     

Systematic Evaluation of One-Dimensional Unsteady Friction Models in Simple Pipelines

In this paper, basic unsteady flow types and transient event types are categorized, and then unsteady friction models are tested for each type of transient event. One important feature of any unsteady friction model is its ability to correctly model frictional dissipation in unsteady flow conditions under a wide a range of possible transient event types. This is of importance to the simulation of transients in pipe networks or pipelines with various devices in which a complex series of unsteady flow types are common. Two common one-dimensional unsteady friction models are considered, namely, the constant coefficient instantaneous acceleration-based model and the convolution-based model. The modified instantaneous acceleration-based model, although an improvement, is shown to fail for certain transient event types. Additionally, numerical errors arising from the approximate implementation of the instantaneous acceleration-based model are determined, suggesting some previous good fits with experimental data are due to numerical error rather than the unsteady friction model. The convolution-based model is successful for all transient event types. Both approaches are tested against experimental data from a laboratory pipeline.     

The development and initial evaluation of the Survey of Readiness for Alcoholics Anonymous Participation.

This article presents 5 studies related to the development and initial evaluation of the Survey of Readiness for Alcoholics Anonymous Participation (SYRAAP). The SYRAAP is a brief, multidimensional, self-administered instrument that assesses beliefs associated with Alcoholics Anonymous (AA) participation. Study 1 generated 239 candidate items for potential inclusion in the instrument. Study 2 assessed the content validity of these items according to 3 criteria and identified a subset of 60 with the highest values on the criteria for further consideration. Study 3 produced a shorter version of the SYRAAP and evaluated its structure, internal reliability, and validity. Study 4 reevaluated the structure and internal reliability of the SYRAAP and yielded findings that were generally consistent with those from Study 3. Study 5 established stability reliability for the instrument. The collective findings indicated the SYRAAP can reliably and validly assess individual-level beliefs associated with AA participation. The potential use of the SYRAAP for researchers and clinicians, along with limitations of the work presented here, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Providing user models direct access to interfaces: an exploratory study of a simple interface with implications for HRI and HCI

Models of users are a way to understand and improve the usability of computer interfaces. We present here a model in ACT-R cognitive-modeling language that interacts with a publicly available driving simulation as a simple analog for robot interfaces. The model interacts with the unmodified Java interface by incorporating a novel use of bitmap parsing. The model's structure starts to describe the knowledge a human operator of a robot must have. The model also indicates some of the aspects of the task will be difficult for the operator. For example, the model's performance makes quantitative predictions about how robot speed will influence navigation quality, correlating well to human performance. While the model does not cover all aspects of human-robot interaction, it illustrates how providing user models access to an interface through its bitmap can lead to more accurate and more widely applicable model users.