选择正确的PFC解决方案

本文用一种创新的方法提出了四种功率因数校正(PFC)电路设计。两种临界导通模式(CRM)升压．一种连续导通模式(CCM)升压和一种CCM单段回扫，并且推荐了基于功率要求、效率、失真程度、电路板空间和成本限制的解决方案。     

Distraction 'on the buses': a novel framework of ergonomics methods for identifying sources and effects of bus driver distraction

Driver distraction represents a significant problem in the public transport sector. Various methods exist for investigating distraction; however, the majority are difficult to apply within the context of naturalistic bus driving. This article investigates the nature of bus driver distraction at a major Australian public transport company, including the sources of distraction present, and their effects on driver performance, through the application of a novel framework of ergonomics methods. The framework represents a novel approach for assessing distraction in a real world context. The findings suggest that there are a number of sources of distraction that could potentially distract bus drivers while driving, including those that derive from the driving task itself, and those that derive from the additional requirements associated with bus operation, such as passenger and ticketing-related distractions. A taxonomy of the sources of bus driver distraction identified is presented, along with a discussion of proposed countermeasures designed to remove the sources identified or mitigate their effects on driver performance.     

The implications of cross-regional differences for the design of In-vehicle Information Systems: a comparison of Australian and Chinese drivers

The increasing global distribution of automobiles necessitates that the design of In-vehicle Information Systems (IVIS) is appropriate for the regions to which they are being exported. Differences between regions such as culture, environment and traffic context can influence the needs, usability and acceptance of IVIS. This paper describes two studies aimed at identifying regional differences in IVIS design needs and preferences across drivers from Australia and China to determine the impact of any differences on IVIS design. Using a questionnaire and interaction clinics, the influence of cultural values and driving patterns on drivers' preferences for, and comprehension of, surface- and interaction-level aspects of IVIS interfaces was explored. Similarities and differences were found between the two regional groups in terms of preferences for IVIS input control types and labels and in the comprehension of IVIS functions. Specifically, Chinese drivers preferred symbols and Chinese characters over English words and were less successful (compared to Australians) at comprehending English abbreviations, particularly for complex IVIS functions. Implications in terms of the current trend to introduce Western-styled interfaces into other regions with little or no adaptation are discussed.     

Faceless students, virtual places: Emergence and communal accountability in online classrooms

A pedagogical problem growing out of virtual classrooms is the temptation to act without communal accountability, the reciprocal commitment among individuals to maintain the health of their interconnections. Drawing on an ethnographic study of a fully online composition class, I argue that teachers can encourage accountability within virtual sites by conceiving of the online classroom as an emergent phenomenon. The relationships and activities among language, physical reality, and interpretant provide the matrix out of which place organizes itself. This ecological orientation provides local and systemic strategies for fostering communal health. I begin my exploration of online place by describing the value of complex systems theory and emergence for conceptualizing place. Next, I describe the roles of language, physical reality, and interpretant, pointing out the contribution of each to the configuration of virtual place and to communal accountability. Then, I focus on the emergence of place, which reorganizes language, reality, and interpretant, opening up a new dimension to communal accountability.     

Discrepancy between predicted and obtained WAIS–R IQ scores discriminates between traumatic brain injury and insufficient effort.

This study examines how well the discrepancy between predicted and obtained Wechsler Adult Intelligence Scale–Revised (WAIS–R) scores discriminate between insufficient effort (IE) and traumatic brain injury (TBI). The 27 IE patients performed significantly more poorly on the WAIS–R than the 48 moderate-severe TBI patients. Premorbid IQs were calculated with formulae that use demographics (Barona Index) or demographics and WAIS–R performance (Best-3 and the Oklahoma Premorbid Intelligence Estimation). Predictions were similar on the Barona, but IE patients' predicted IQs were lower than TBIs for measures with a performance component. IE patients demonstrated a greater discrepancy score (i.e., predicted IQ—obtained IQ) than TBIs; variable levels of sensitivity and specificity were obtained when discriminate functions were developed on these scores. The potential advantage of using discrepancy scores versus performance-based measures to detect insufficient effort is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pinched Cord and Overdriven Staple Failures: Research on the Causation of an Electrical Fire

In the past, some fire investigators have determined the cause of a fire to be electrical in nature based, in part, on the presence of an electrical cord or cable found beneath a furniture leg or a cable wedged tightly under a staple. While fires resulting from these events are possible, the mechanisms that lead to these failures are poorly understood. In this paper, the results of four research projects are presented. The first three projects focused on the creation of a pinched cord failure under various current loads and pressures. In the last project, a typical nonmetallic-sheathed cable was damaged and then installed with an overdriven staple over the damaged location. In all tests, the cords and cables were subjected to current loads varying between 100 and 250% of the rated ampacity. The failure rate of pinched cords was approximately 1%, but required the use of overloaded circuits and pre-existing damage or special orientation of the cord under test. A critical factor worth considering with these failures, which is often not accounted for, is time. These failures may take weeks, months, or years to occur under normal conditions, although some investigators may assume they develop nearly instantaneously. The conditions of the circuit are also important, as the only way a failure developed in these tests was by operating the circuits in excess of their rated parameters.     

一种新型的膏体充填工艺技术

膏体充填技术作为一种将选矿尾砂排放坑内采空区并形成坚固支承体的充填技术,从20世纪80年代初期就已经在加拿大地下矿山开始使用.然而,早期的膏体充填系统设备昂贵、能耗较高,使得地下矿山最近几年来开始探求一种更经济有效的充填技术.针对这个问题,现在已经研发出一种相应的技术,它能将选矿尾砂通过沉淀、浓缩和流态化过程制出膏体.加拿大矿物能源工艺中心(CANMET)在这种新工艺的研究中所取得的成果表明,选矿尾砂能在一个尾砂仓内通过浓缩和流态过程而制成膏体用于矿山充填.     

Quantitative analysis of trace chromium in blood samples. Combination of the advanced oxidation process with catalytic adsorptive stripping voltammetry

A new method for pretreating blood samples for trace Cr analysis is described. The advanced oxidation process (AOP with H2O2 and 5.5-W UV irradiation for 60 min) is used to remove biological/organic species for subsequent analysis. Prior to the AOP pretreatment, acid (HNO3) is used at pH 3.0 to inhibit the enzyme catalase in the blood samples. Catalytic adsorptive stripping voltammetry at a bismuth film electrode gives a Cr concentration of 6.0 +/- 0.3 ppb in the blood samples. This concentration was confirmed by dry-ashing the blood samples and subsequent analysis by atomic absorption spectroscopy. This current method may be used to monitor chromium, a trace metal in humans, and the efficacy and safety of chromium supplements as adjuvant therapy for diabetes.     

Effects of magnetic doping on weak antilocalization in narrow bi(2)se(3) nanoribbons

We report low-temperature, magnetotransport measurements of ferrocene-doped Bi(2)Se(3) nanoribbons grown by vapor-liquid-solid method. The Kondo effect, a saturating resistance upturn at low temperatures, is observed in these ribbons to indicate presence of localized impurity spins. Magnetoconductances of the ferrocene-doped ribbons display both weak localization and weak antilocalization, which is in contrast with those of undoped ribbons that show only weak antilocalization. We show that the observed magnetoconductances are governed by a one-dimensional localization theory that includes spin orbit coupling and magnetic impurity scattering, yielding various scattering and dephasing lengths for Bi(2)Se(3). The power law decay of the dephasing length on temperature also reflects one-dimensional localization regime in these narrow Bi(2)Se(3) nanoribbons. The emergence of weak localization in ferrocene-doped Bi(2)Se(3) nanoribbons presents ferrocene as an effective magnetic dopant source.     

Intelligent speed adaptation—Effects and acceptance by young inexperienced drivers

This study assessed the relative effects of two intelligent speed adaptation (ISA) systems (informative and actively supporting) on simulated driving performance and acceptability in a sample of inexperienced and experienced drivers. Participants drove a series of simulated drives under three conditions: no ISA (control), ISA informative and ISA actively supporting. The informative system significantly reduced speed and was particularly effective in reducing top-end speeds. Comparable reductions were not found for the actively supporting system. Differences in the effectiveness and acceptability of ISA systems were noted across experienced and inexperienced drivers. The ISA systems appeared more effective at reducing speeds for experienced drivers on some road types. Experienced drivers’ subjective satisfaction ratings of the systems also remained constant over the trial, whereas the inexperienced drivers’ ratings changed after experience. There was little evidence that drivers engaged in negative behavioral adaptation and no evidence that subjective workload levels increased with ISA use. Future directions for examining the safety benefits of ISA, particularly for inexperienced drivers, are discussed.