基于恒刚度剪切试验的预制桩侧阻退化估计

采用双向循环恒刚度剪切试验对预制桩的侧阻退化效应进行试验研究。研究显示，剪切应力（摩阻力）随剪切循环数的增加呈指数型衰减，衰减主要发生在开始的部分循环内，约 25 个循环后基本达到稳定。剪切过程中剪切带发生明显的剪缩，导致法向应力释放，此为摩阻力退化的 原因之一 。随剪切循环数的增加界面摩擦角发生指数型退化直至达到残余值，此为摩阻力退化的另一原因。法向刚度的大小决定剪切应力、法向应力和界面摩擦角衰减的速度和幅度，法向刚度越大，衰减越快且残余值越小。恒刚度剪切试验说明桩土界面摩擦力的退化与桩周土的坚硬程度密切相关，土体越硬则侧阻退化现象越明显。     

Dependency of removal efficiency on electrode arrangements in the treatment of oily wastewaters by electrocoagulation

Turbidity and chemical oxygen demand (COD) removal efficiencies were analyzed depending on electrode layouts by performing electrocoagulation experiments using horizontal and vertical electrochemical cells. Multiple aluminum plate electrodes were placed into different sections of the electrochemical cells. Removal efficiencies at the horizontal electrochemical cell were always higher than the one’s obtained from the vertical electrochemical cell. But the use of vertical electrochemical cell consumed less energy during the electrocoagulation tests. The highest COD removal efficiencies were 97% and 88% in the horizontal and vertical electrochemical cells, respectively. However, the energy consumption for COD removal in the horizontal electrochemical cell was 47% higher than the energy consumed in the vertical electrochemical cell.     

Structural modifications in stretch-induced crystallization in PVDF films as measured by small-angle X-ray scattering

The nanostructure of stretched and nonstretched PVDF samples was studied by small-angle X-ray scattering (SAXS). The crystallinity of the samples was determined by wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC), and crystalline phases by Fourier transform infrared spectroscopy (FTIR). The nanostructure can be described by a lamellar stacking of crystalline and amorphous layers, with a fairly well defined long period D and a diffuse-boundary in the interface between the crystalline and amorphous phases. The crystallinity of the stretched sample was found to be greater than that of the nonstretched sample. The long period D and the thicknesses of the crystalline lamellae T_c were found to be greater in the stretched sample than those in the nonstretched sample. The thickness of the diffuse-boundary was evaluated as being ∼ 1.4 nm in the nonstretched sample and 1.1 nm in the stretched sample. It was concluded that the growth of the thickness of the crystalline layer induced by the stretching process (stretch-induced crystallization) occurs partially at expense of the diffuse boundary and also by the coarsening of the structure with the stretching process, because of the diminution in the surface area to volume ratio observed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Concept maps: A useful and usable tool for computer-based knowledge assessment? A literature review with a focus on usability

The concept map is now widely accepted as an instrument for the assessment of conceptual knowledge and is increasingly being embedded into technology-based environments. Usability addresses how appropriate (for a particular use) or how user-friendly a computer-based assessment instrument is. As we know from human-computer interaction research, if the interface is not user-friendly, a computer-based assessment can result in decreased test performance and reduced validity. This means that the usability of the interface affects the assessment in such a way that if the test is not user-friendly, then the test taker will not be able to fully demonstrate his/her level of proficiency and will instead be scored according to his/her information and communication technology (ICT) literacy skills. The guidelines of the International Test Commission (2006) require usability testing for such instruments and suggest that design standards be implemented. However, we do not know whether computer-conducted concept map assessments fulfill these standards. The present paper addresses this aspect. We conducted a systematic research review to examine whether and how researchers have studied and considered usability when conducting computer-based concept map assessments. Only 24 out of 119 journal articles that assessed computer-based concept maps discussed the usability issue in some way. Nevertheless, our review brings to light the idea that the impact of usability on computer-based concept map assessments is an issue that has received insufficient attention. In addition, usability ensures a suitable interaction between test taker and test device; thus, the training effort required for test use can be reduced if a test's usability is straight forward. Our literature review, however, illustrates that the interplay between usability and test use training has mostly been neglected in current studies.     

PolyMorph: Increasing the Spelling Efficiency of P300 by Selection Matrix PolyMorphism and Sentence-Based Predictions

One application of the P300 brain electric signal is sentence spelling, which enables subjects who have lost control of their motor pathways to communicate by selecting characters in a matrix containing all alphabet symbols. This technology still suffers from both low communication/high error rates. A P300 speller, named PolyMorph, which jointly introduces the selection matrix polymorphism (reducing the matrix size by removing useless symbols) and sentence-based predictions (which forecast words on the basis of language statistics) is presented. This is accomplished by using a custom dynamic knowledge-base, tailored to the subject lexicon, and updated in real time with the selections of the subject. The effectiveness of the presented speller is measured in vivo and in silico. The results suggest that the use of PolyMorph increases the number of spelt characters per time unit and reduces the error rate.     

Gain scheduling adaptive control applied to a particular mixer-settler equipment

The mixer-settler based on phase inversion (MSBPI) is a system used for treatment of wastewaters in order to reduce the content of oils and greases from wastewaters produced in oil industry. Its operation principle combines mixing, extraction and separation by decantation in a unique process. In particular, for control purpose, the level of the interface between organic solvent and water, in the separation section, is a critical variable to guarantee performance and security during operation of the MSBPI. In this work, an image-based detector to monitor the organic solvent–water interface level is proposed and a feedback control loop for the process is presented. Initially, a conventional controller (PID) was implemented and, subsequently, a strategy of gain scheduling adaptive control was developed in order to improve the process response in closed-loop. The experimental results showed that the adaptive control presented an efficient performance, even when disturbances of significant magnitude were applied to the process.     

Metasearching

ABSTRACT

This is a selective annotated bibliography of journal articles and electronic resources relating to metasearching and metasearch tools. This bibliography is intended as a guide to the resources available to assist librarians and other information professionals interested in implementing or enhancing their metasearch projects. In addition to reviewing the major topics addressed in the publications, each annotation summarizes the important conclusions reached by the authors of the works. doi:10.1300/J136v12n03_11     

A tool for the automatic generation and analysis of regular analog layout modules

This paper describes the characteristics of a new CAD tool that enables the creation of layout libraries of selected analog modules. This Analog Modules Generator (AMG) automatically creates multiple layout versions of two commonly used analog structures: the differential pair and arrays of series-connected or stacked devices, for the subsequent generation of layout libraries. Based on the number of devices and rows defined by the user for the layout implementation, the tool validates all possible implementations, which are later saved in a database. Additionally, an extraction process can be optionally executed over all the layout views saved in the database. The AMG generates several reports with all the characteristics of the implemented layouts, including area and parasitic components, facilitating further statistical processing. We describe the features and capabilities of the proposed AMG tool, and several test cases are presented. Results show that suitable layout implementations can be achieved by layout and circuit designers in a very reduced amount of time.     

A game for emotional regulation in adolescents: The (body) interface device matters

The aim of this study is to evaluate the role of the type of interface device in the efficacy of a serious game that teaches emotional regulation (ER) strategies in a non-clinical sample of adolescents. We conducted a between-participants experiment in which participants (N = 61) played a frustration induction game, and then an ER game (a breathing strategy game), using one of three types of devices (computer, smartphone, and RGB-D camera). Frustration mood and perceived arousal were the main variables measured. Results revealed a significant interaction between moment (pre-induction phase, post-induction phase, and regulation phase) and the type of interface device used in the frustration mood scores. In participants who used the computer and smartphone, frustration increased after the induction phase and decreased after the regulation phase. However, for participants who used the RGB-D camera, frustration decreased significantly after the induction phase, and this change was maintained after the regulation phase. Changes in arousal were similar with the three devices. This study highlights that the type of interface device (and specifically, the participation of the body) is a crucial variable in the efficacy of serious games affecting users’ emotional experience.