A two-dimensional numerical study of the flow inside the combustion chambers of a motored rotary engine

A numerical study was performed to investigate the unsteady, multidimensional flow inside the combustion chambers of an idealized, two-dimensional, rotary engine under motored conditions. The numerical study was based on the time-dependent, two-dimensional, density-weighted, ensemble-averaged conservation equations of mass, species, momentum, and total energy valid for two-component ideal gas mixtures. The ensemble-averaged conservation equations were closed by a K-epsilon model of turbulence. This K-epsilon model of turbulence was modified to account for some of the effects of compressibility, streamline curvature, low-Reynolds number, and preferential stress dissipation. Numerical solutions to the conservation equations were obtained by the highly efficient implicit-factored method of Beam and Warming. The grid system needed to obtain solutions were generated by an algebraic grid generation technique based on transfinite interpolation. Results of the numerical study are presented in graphical form illustrating the flow patterns during intake, compression, gaseous fuel injection, expansion, and exhaust

Life cycle assessment of biogas used for the provision of thermal household energy in developing countries

The utilization of dried dung as fuel for household cooking stoves is very common in rural areas of developing countries. The objective of this study was to compare the environmental impacts for the provision of cooking heat from biogas with the utilization of dung cakes. For this purpose, the method of life cycle assessment was used for assessing the impact categories global warming potential, acidification potential, eutrophication potential and human toxicity potential. The results show that anaerobic digestion at household scale can contribute to the reduction of greenhouse gases (GHG?s) as well as several other emissions in rural areas

The adjustment of South African immigrants to the United Kingdom: The development of a scale and an exploration of contributing factors

The topic of South African emigration has always been considered in political terms. The present study focuses specifically on the psychological aspects of South African immigrants in the UK. The adjustment of a sample of white, middle-class South Africans is examined, and the relationship between their psychological adjustment and a number of predictors is explored. Gender, support, education, length of stay, the number of reasons for leaving South Africa and marital status were taken into account to understand three measures of 'adjustment' and two measures of psychological state'. Two hundred and sixteen South African immigrants responded to a survey mailed in 1996. The survey contained two standardized mental health measures: the General Health Questionnaire (GHQ-12, Goldberg, 1978), the Rosenberg Self-Esteem Scale (RSE, Rosenberg, 1965), and a scale developed specifically by the researcher: "The South African Settlement Scale" (SASS). Satisfaction items were included in the six-part survey and biographical and other information were elicited by means of open-ended questions. A factor analysis of the 30-item SASS revealed five factors which corresponded closely to the dimensions proposed by Taft (1987) for the analysis of immigrant adjustment. The SASS proved to have good reliability and there was some evidence supporting construct validity. Multiple regression analyses were performed to explore the relationships between three measures of adjustment’, two measures of 'psychological state', the length and degree of migration stress and a set of six predictors. Results indicated that length of time in the UK, education and reliable support were the most significant predictors of positive adjustment. Gender was found to be a reliable predictor of self-esteem and the degree of migration stress, and was approaching significance as a predictor of symptomatology. The number of reasons for leaving South Africa only predicted self-rated adjustment and symptomatology with slight significance. Neither age nor marital status appeared to have any effect on adjustment. The study showed that as a group, white, middle-class South Africans are satisfied with life in the UK, they are well-adjusted and they have high levels of self-esteem. While the generalizability of the results is clearly limited, the study provides a valuable, first contribution to knowledge about South African settlers and baseline data for future comparisons. Some further limitations of the present study are considered. Suggestions are made for the facilitation of the psychological and social adjustment of people making the transition and for future research

Energy End-Use Technologies for the 21st Century. A Report of the World Energy Council

This report makes clear the opportunities and places technology development firmly centre stage in meeting and overcoming the challenges confronting the energy industry and policy makers. Energy End-Use Technologies for the 21st Century makes it crystal clear that technologies deployed in 20 to 50 years will be the result of policy and funding decisions taken now and that we cannot afford to duck these decisions if we are to meet the World Energy Council’s goals of energy availability, accessibility and acceptability

Time resolved investigation of Cu In,Ga Se2 growth and Ga gradient formation during fast selenization of metallic precursors

Ga segregation at the backside of Cu In,Ga Se2 solar cell absorbers is a commonly observed phenomenon for a large variety of sequential fabrication processes. Here, we investigate the correlation between Se incorporation, phase formation and Ga segregation during fast selenisation of Cu In Ga precursor films in elemental selenium vapour. Se incorporation and phase formation are analysed by real time synchrotron based X ray diffraction and fluorescence analysis. Correlations between phase formation and depth distributions are gained by interrupting the process at several points and by subsequent ex situ cross sectional electron microscopy and Raman spectroscopy. The presented results reveal that the main share of Se incorporation takes place within a few seconds during formation of In Se at the top part of the film, accompanied by outdiffusion of In out of a ternary Cu In Ga phase. Surprisingly, CuInSe2 starts to form at the surface on top of the In Se layer, leading to an intermediate double graded Cu depth distribution. The remaining Ga rich metal phase at the back is finally selenised by indiffusion of Se. On the basis of a proposed growth model, we discuss possible strategies and limitations for the avoidance of Ga segregation during fast selenisation of metallic precursors. Solar cells made from samples selenised with a total annealing time of 6.5 amp; 8201;min reached conversion efficiencies of up to 14.2 total area, without anti reflective coating . The evolution of the Cu In,Ga Se2 diffraction signals reveals that the minimum process time for high quality Cu In,Ga Se2 absorbers is limited by cation ordering rather than Se incorporatio

CdS/Cu(In,Ga)S2 based solar cells with efficiencies reaching 12.9% prepared by a rapid thermal process

In this letter, we report externally confirmed total area efficiencies reaching up to 12.9% for CdS/Cu(In,Ga)S2 based solar cells. These are the highest externally confirmed efficiencies for such cells. The absorbers were prepared from sputtered metals subsequently sulfurized using rapid thermal processing in sulfur vapor. Structural, compositional, and electrical properties of one of these champion cells are presented. The correlation between the Ga distribution profile and solar cell properties is discussed

A connectivity mapping approach predicted acetylsalicylic acid (aspirin) to induce osteo/odontogenic differentiation of dental pulp cells

International audienc

Deep learning-based post-processing of real-time MRI to assess and quantify dynamic wrist movement in health and disease

While morphologic magnetic resonance imaging (MRI) is the imaging modality of choice for the evaluation of ligamentous wrist injuries, it is merely static and incapable of diagnosing dynamic wrist instability. Based on real-time MRI and algorithm-based image post-processing in terms of convolutional neural networks (CNNs), this study aims to develop and validate an automatic technique to quantify wrist movement. A total of 56 bilateral wrists (28 healthy volunteers) were imaged during continuous and alternating maximum ulnar and radial abduction. Following CNN-based automatic segmentations of carpal bone contours, scapholunate and lunotriquetral gap widths were quantified based on dedicated algorithms and as a function of wrist position. Automatic segmentations were in excellent agreement with manual reference segmentations performed by two radiologists as indicated by Dice similarity coefficients of 0.96 ± 0.02 and consistent and unskewed Bland–Altman plots. Clinical applicability of the framework was assessed in a patient with diagnosed scapholunate ligament injury. Considerable increases in scapholunate gap widths across the range-of-motion were found. In conclusion, the combination of real-time wrist MRI and the present framework provides a powerful diagnostic tool for dynamic assessment of wrist function and, if confirmed in clinical trials, dynamic carpal instability that may elude static assessment using clinical-standard imaging modalities