Small-signal modeling and control of the quasi-square-wave boostconverter

Sampled-data techniques are used to examine the dynamic characteristics and closed-loop performance of the quasi-square-wave boost converter. Direct duty-ratio control and current-mode control are considered. With direct duty-ratio control, the system poles remain well damped under all load conditions, and there is no zero in the control-to-output transfer function. Good closed-loop performance is therefore achieved. Under current-mode control, the requirement for a stabilizing ramp is seen to depend on load conditions, and the achievable voltage control-loop bandwidth is smaller than that using direct duty-ratio control; however, there is a significant reduction in the magnitude of the DC source to output-voltage frequency response     

Extended fundamental frequency analysis of the LCC resonant converter

Fundamental frequency techniques are used to analyze the series-parallel resonant converter under heavy load conditions, both with a continuous, but distorted parallel capacitor voltage waveform, and with a discontinuous capacitor voltage waveform. The analysis is validated with results from an experimental prototype. The application of the technique to the parallel-loaded L-C resonant converter is also considered.     

Response intensity in content-specific fear conditioning comparing 20% versus 13% CO?-enriched air as unconditioned stimuli.

This study examined the relation between the intensity of CO?-induced psychophysiological responses and content-specific fear conditioning. Sex-balanced groups of undergraduates (N?=?96) were assigned to 1 of 3 conditioned stimuli (CSs) differing in fear-relevance, and within each CS, to either 20% or 13% CO?-enriched air (unconditioned stimuli [UCS]). Several psychophysiological measures were assessed before, during, and following conditioning phases. Consistent with expectation, electrodermal and cardiac conditioned responses were larger and more resistant to extinction when associated with fear-relevant compared with fear-irrelevant stimuli, and this overall effect of fear-relevance was more robust to the more intense UCS. Severity and frequency of DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, 4th ed ) panic symptoms also varied reliably with UCS intensity, and women reported more distress and symptoms than men. Overall, the findings suggest that content-specific fear conditioning is mediated, in part, by the intensity of the bodily response. The authors discuss clinical and theoretical implications for understanding fear onset in the absence of obvious environmental pain or trauma. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The trouble with AI

This paper argues that AI is best defined in terms of its implicit goal—the creation of thinking beings by means other than biological reproduction. Thus AI can be seen as a devious and sophisticated form of birth control. A discussion of the prospects for AI research from this viewpoint follows. It is concluded that the total extermination of the human species would be a better test of whether AI has succeeded than Turing's celebrated imitation game.     

Discipline-based instruction to promote interdisciplinary design of wearable and pervasive computing products

This paper reports on a design experience for undergraduates in computer engineering, industrial design, and marketing that focuses on pervasive computing devices. Across a broad range of targeted application areas and user groups, many of the student designs have been wearable computers. Consequently, our course will be of interest to the wearable computing community, particularly in terms of our aim of bridging the gap between design and engineering. For the two most recent offerings of the course, we have utilized external observers and surveyed the students in order to validate the impact of aspects of our process and changes to it. This paper is based upon 5 years of experience and 2 years of analysis of our course, and it presents an overview of our process with both qualitative and quantitative results from these two most recent offerings.     

Characterization of surface deformation with the Edge of LightTM technique

The aircraft lap joints are inspected with an enhanced visual inspection technique named “Edge of Light”, which is patented by the NRC Institute for Aerospace Research. This technique is applicable for rapid detection of possible hidden corrosion in lap joints. The surface deformation due to hidden corrosion can be characterized by this optical-based inspection method. In this study, a calibration procedure is developed to quantify the lap joint surface deformation. The effect of surface reflectivity is investigated with the solid film highlighting technique (SolidHi^TM), which helps achieve a uniform reflectivity during the inspection. The efficiency of the technique is demonstrated with the experimental results. This work is supported by NRC-IAR New Initiative Research Funding.     

Fatigue crack growth rates for very short cracks developing at fastener holes in 7075 and 7010 aluminium alloys

Fatigue crack growth rates have been determined for very short corner and bore cracks developing from fastener holes. This was made possible by the use of a simple load programme which provided a contrasting fracture feature or marker. The programme consisted of a high-low-high switch of load ratio (R) usually in blocks of 100 loads. A constant was maintained within each block. The crack growth rate data for short cracks was in reasonable agreement with the published long crack data for 7075 and 7010 alloy. Strong retardation effects were in evidence and certain features of the fractures shed new light on the retardation models, and also on those of fatigue fracture itself.     

Temporal discounting of rewards in patients with bipolar disorder and schizophrenia.

Patients with bipolar disorder (BD) and schizophrenia (SZ) often show decision-making deficits in everyday circumstances. A failure to appropriately weigh immediate versus future consequences of choices may contribute to these deficits. We used the delay discounting task in individuals with BD or SZ to investigate their temporal decision making. Twenty-two individuals with BD, 21 individuals with SZ, and 30 healthy individuals completed the delay discounting task along with neuropsychological measures of working memory and cognitive function. Both BD and SZ groups discounted delayed rewards more steeply than did the healthy group even after controlling for current substance use, age, gender, and employment. Hierarchical multiple regression analyses showed that discounting rate was associated with both diagnostic group and working memory or intelligence scores. In each group, working memory or intelligence scores negatively correlated with discounting rate. The results suggest that (a) both BD and SZ groups value smaller, immediate rewards more than larger, delayed rewards compared with the healthy group and (b) working memory or intelligence is related to temporal decision making in individuals with BD or SZ as well as in healthy individuals. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Determination of perchlorate in infant formula by isotope dilution ion chromatography/tandem mass spectrometry

A sensitive and selective isotope dilution ion chromatography/tandem mass spectrometry (ID IC-MS/MS) method was developed and validated for the determination of perchlorate in infant formula. The perchlorate was extracted from infant formula by using 20 ml of methanol and 5 ml of 1% acetic acid. All samples were spiked with (18)O(4) isotope-labelled perchlorate internal standard prior to extraction. After purification on a graphitised carbon solid-phase extraction column, the extracts were injected into an ion chromatography system equipped with an Ionpac AS20 column for separation of perchlorate from other anions. The presence of perchlorate in samples was quantified by isotope dilution mass spectrometry. Analysis of both perchlorate and its isotope-labelled internal standard was carried out on a Waters Quattro Ultima triple quadrupole mass spectrometer operating in a multiple reaction monitoring (MRM) negative ionisation mode. The method was validated for linearity and range, accuracy, precision, sensitivity, and matrix effects. The limit of quantification (LOQ) was 0.4 μg l(-1) for liquid infant formula and 0.95 μg kg(-1) for powdered infant formula. The recovery ranged from 94% to 110% with an average of 98%. This method was used to analyse 39 infant formula, and perchlorate concentrations ranging from 相似文献