Transient electrothermal simulation of power semiconductor devices

In this paper, a new thermal model based on the Fourier series solution of heat conduction equation has been introduced in detail. 1-D and 2-D Fourier series thermal models have been programmed in MATLAB/Simulink. Compared with the traditional finite-difference thermal model and equivalent RC thermal network, the new thermal model can provide high simulation speed with high accuracy, which has been proved to be more favorable in dynamic thermal characterization on power semiconductor switches. The complete electrothermal simulation models of insulated gate bipolar transistor (IGBT) and power diodes under inductive load switching condition have been successfully implemented in MATLAB/Simulink. The experimental results on IGBT and power diodes with clamped inductive load switching tests have verified the new electrothermal simulation model. The advantage of Fourier series thermal model over widely used equivalent RC thermal network in dynamic thermal characterization has also been validated by the measured junction temperature

A Multiplexed Sonomyography System for Proprioceptive Proportional Control of Biomechatronic Interfaces

Sonomyography is an ultrasound-imaging-based technique that measures muscle activity. Real-time imaging of deep-seated muscle activity enables robust and intuitive biomechatronic control. However, the form factor of clinical ultrasound systems limits the practical utility of sonomyography. Therefore, recent investigations aim towards developing wearable ultrasound systems to utilize sonomyography for biomechatronic interfacing. In this paper, a wearable, multiplexed sonomyography transducer array for real-time sensing muscle activity has been presented. The forearm-muscle activity was quantified using a computationally inexpensive, correlation-based metric to generate a sonomyography signal. The sonomyography signal was then used to perform a human-computer interaction-based target achievement task involving one degree of freedom control in real-time. Results show that participants achieved the targets with an average success rate of > 96 % for a target width of 10%, with minimal training. The results demonstrate the potential of a multiplexed sonomyography system for intuitive control of biomechatronic interfaces

Capabilities, competitive advantages, and performance of apparel import intermediaries in a hyper-dynamic market environment

Structural changes in the global apparel industry have led to a new market environment in which part of the apparel channel members (specifically, apparel import intermediaries or AIIs) have had to assume new market responsibilities and have taken different approaches to their conventional functional activities. The purpose of this study was to investigate the basic nature of these firms' business operations, that is, the relationships among AIIs' capabilities, competitive advantages, and performance in the hyper-dynamic market environment of the apparel industry. In order to do so, this study (a) developed an integrative model of AIIs' capabilities, competitive advantages, and performance; and (b) conducted an empirical assessment of the model, using survey methodology. Drawing from the first phase qualitative interview studies, extant theory, and literature in the strategy, marketing, and organizational management disciplines, the study proposed an integrative model of AIIs' capabilities, competitive advantages, and performance. A survey was developed to test the causal relationships of these three major constructs of interest. Subsequently, 807 firms were randomly drawn from ReferenceUSA, an Internet-based firm database that includes U.S. apparel manufacturers and wholesalers. Out of an adjusted sample of 736 firms, a total of 159 firms returned usable surveys, resulting in a 21.6% response rate. Structural Equation Modeling was employed for data analysis using LISREL 8.72 and tested the causal relationships among AIIs' capabilities, competitive advantages, and performance. Overall, the study's findings supported the predicted positive impact between AIIs' capabilities of market interpretation, sourcing, and service and the competitive advantages of cost, product, and service. The results also supported the predicted positive impact between AIIs' competitive advantages and their relationship performance with domestic clients and foreign suppliers. Consistent with the resource-advantage theory of competition, the study supported the role of competitive advantages as the direct antecedents of AII performance and the role of functional capabilities as the indirect antecedents of performance. This study concluded with research contributions and implications, study limitations, and directions for future researc

Traditional Underground Grain Storage in Clay Soils in Sudan Improved by Recent Innovations

In the central clay plain of the Sudan, traditional subsistence farmers and small farmers that also produce for local markets want to keep the region near food self-sufficiency. They combine annual production of sorghum with underground pit storage of part of the harvest. With increasing climate variability this food security is coming more and more under pressure. Farmers recently experimented with pit innovations that would allow storage for more than one season. These innovations were quantified and further improvements were suggested. It was found that in the most abundantly occurring cracking clay soils, wide shallow pits, using thick chaff linings, with wider above ground soil caps, are most suitable for longer term storage

An optimization approach for equitable bicycle share station siting

Bicycle share systems are becoming an increasingly popular feature of many urban areas across the United States. While these systems aim to increase transit mode options as well as overall bicycle ridership, bike share programs also face challenges and criticisms related to density and inequitable distribution of services. Key factors in the success of bicycle share include high station density as well as services that reach a variety of neighborhoods, though many current systems do not reach low-income areas. Equitable station distribution therefore appears to be a complex problem to address. We propose utilizing spatial analytics, including GIS and spatial optimization, to help site bicycle share stations across an urban region. Specifically we seek to apply a covering model to assess how many bicycle stations are needed, and where they should be located, so no user would have to travel too far for access. The city of Phoenix, Arizona, is used as a case study to illustrate the coverage and access tradeoffs possible through different investment strategies. Accordingly, for a given investment level, the set of stations is identified that provides the best access to the designated bike path network for the greatest number of potential users. Further, tradeoff options that differentially favor either network or population coverage are possible, and can be identified and evaluated through the proposed analytical framework

Integration of SWAT and QUAL2K for water quality modeling in a data scarce basin of Cau River basin in Vietnam

© 2019 European Regional Centre for Ecohydrology of the Polish Academy of Sciences Water quality modeling in a river basin often faces the problem of having a large number of parameters yet limited available data. The important inputs to the water quality model are pollution concentrations and discharge from river tributaries, lateral inflows and related pollution load from different sources along the river. In general, such an extensive data set is rarely available, especially for data scarce basins. This makes water quality modeling more challenging. However, integration of models may be able to fill this data gap. Selection of models should be made based on the data that is available for the river basin. For the case of Cau River basin, the SWAT and QUAL2K models were selected. The outputs of SWAT model for lateral inflows and discharges of ungauged tributaries, and the observed pollutant concentrations data and estimated pollution loads of sub-watersheds were used as inputs to the water quality model QUAL2K. The resulting QUAL2K model was calibrated and validated using recent water quality data for two periods in 2014. Four model performance ratings PBIAS, NSE, RSR and R2 were used to evaluate the model results. PBIAS index was chosen for water quality model evaluation because it more adequately accounted for the large uncertainty inherent in water quality data. In term of PBIAS, the calibration and validation results for Cau River water quality model were in the “very good” performance range with ǀPBIASǀ < 15%. The obtained results could be used to support water quality management and control in the Cau River basin

Maximum static inspiratory and expiratory pressures with different lung volumes

BACKGROUND: Maximum pressures developed by the respiratory muscles can indicate the health of the respiratory system, help to determine maximum respiratory flow rates, and contribute to respiratory power development. Past measurements of maximum pressures have been found to be inadequate for inclusion in some exercise models involving respiration. METHODS: Maximum inspiratory and expiratory airway pressures were measured over a range of lung volumes in 29 female and 19 male adults. A commercial bell spirometry system was programmed to occlude airflow at nine target lung volumes ranging from 10% to 90% of vital capacity. RESULTS: In women, maximum expiratory pressure increased with volume from 39 to 61 cmH(2)O and maximum inspiratory pressure decreased with volume from 66 to 28 cmH(2)O. In men, maximum expiratory pressure increased with volume from 63 to 97 cmH(2)O and maximum inspiratory pressure decreased with volume from 97 to 39 cmH(2)O. Equations describing pressures for both sexes are: P(e)/P(max )= 0.1426 Ln( %VC) + 0.3402 R(2 )= 0.95 P(i)/P(max )= 0.234 Ln(100 - %VC) - 0.0828 R(2 = )0.96 CONCLUSION: These results were found to be consistent with values and trends obtained by other authors. Regression equations may be suitable for respiratory mechanics models

Reduction of circulating cholesterol and apolipoprotein levels during sepsis

Sepsis with multiple organ failure is frequently associated with a substantial decrease of cholesterol levels. This decrease of cholesterol is strongly associated with mortality suggesting a direct relation between inflammatory conditions and altered cholesterol homeostasis. The host response during sepsis is mediated by cytokines and growth factors, which are capable of influencing lipid metabolism. Conversely lipoproteins are also capable of modulating cytokine production during the inflammatory response. Therefore the decrease in circulating cholesterol levels seems to play a crucial role in the pathophysiology of sepsis. In this review the interaction between cytokines and lipid metabolism and its clinical consequences will be discussed

Effect of Body Mass Index on pregnancy outcomes in nulliparous women delivering singleton babies

Peer reviewedPublisher PD

The biosocial event : responding to innovation in the life sciences

Innovation in the life sciences calls for reflection on how sociologies separate and relate life processes and social processes. To this end we introduce the concept of the ‘biosocial event’. Some life processes and social processes have more mutual relevance than others. Some of these relationships are more negotiable than others. We show that levels of relevance and negotiability are not static but can change within existing relationships. Such changes, or biosocial events, lie at the heart of much unplanned biosocial novelty and much deliberate innovation. We illustrate and explore the concept through two examples – meningitis infection and epidemic, and the use of sonic ‘teen deterrents’ in urban settings. We then consider its value in developing sociological practice oriented to critically constructive engagement with innovation in the life sciences