Turbulent flow in an intake-manifold

Three-dimensional, turbulent fluid flow analysis with computational methods has emerged as a viable tool in the design process of engine components for passenger cars. If applied in the early stages of the component development such analysis can help reduce the product development time drastically, and may support the design engineer to evaluate several competing design aspects before product completion. However the grid generation for complex geometries still poses a difficult and time consuming taks which strongly influences the accuracy of the numerical solution. The present paper studies the numerical solution of the flow in an inlet-manifold of a five-cylinder engine with two intake-ports for each cylinder. A fast and reliable grid generation technique is discussed in detail. The finite volume based Navier-Stokes solver with schemes of first and second order accuracy for the convective terms is used. Numerical results at several mass flow rates and different boundary conditions at the intake ports are compared with measurements. Finally, the computational results are discussed with respect to their applicability to support the design process of an inlet-manifold.     

Strawberry juice colour: The effect of some processing variables on the stability of anthocyanins

The colour stability of juice and purées made from a mixture of two strawberry varieties, stored at + 20°C or at –20°C under aerobic and anaerobic conditions, was studied. High-performance liquid chromatography and spectrophotometric analysis were used to monitor the changes in colour during storage. Pelargonidin 3-glucoside comprised 80% of the total anthocyanin content. Four other pelargonidin-based peaks were found, being 10.4%, 3.5%, 0.7% and 0.3% of the total and two cyanidin peaks were present, being 3.3% and 0.4% of the total. Clarification before storage caused considerable losses in the initial anthocyanin concentrations. Storage conditions (air versus nitrogen) did not influence the rate of loss of anthocyanins during storage or the formation of polymeric pigments. There were no losses in anthocyanins and no increase in the amount of colour measured at 510 nm due to polymers in samples stored at–20°C. Polymerisation occurred in the samples stored at + 20°C, especially in the clarified samples.     

Capturing visual attention and the curve tracing operation.

The hypothesis that orienting visual attention is an important component of visual curve tracing was investigated. Ss examined a visual display and decided as quickly as possible whether 2 dots were on the same or different curves. The rate of tracing was determined by measuring the effects of curve distance on response time. Attention was directed to a curve by momentarily presenting it at a higher luminance. Directing attention to a curve that had 2 dots on it resulted in faster tracing rates with large benefits in overall response time. Directing attention to a distractor curve resulted in slower tracing rates and sizable costs in overall response times. Two alternative nonattentional explanations (eye movements and visible persistence) were examined and rejected. The role of attention in curve tracing is discussed in terms of the selective nature of curve tracing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatiotemporal models for small-area social indicators

This paper investigates spatial effects in a generalized least-squares regression model for small-area social indicators. The significance of using spatial correlation in addition to an intermediate weighting (allowing for sampling and extraneous variation in the indicator) differs according to the index analyzed. It is greater for small-area fertility (over 758 London wards) than for small-area mortality. The model is extended to include serial as well as spatial correlation, then to spatial forecasting. The analyses show that the extent of spatial correlation can vary considerably according to (a) the specification of the form of spatial interaction, and (b) which independent variates are included. Further, spatial effects can be much reduced by including serial correlation.     

如何使转换器不再需要散热器

本文探讨为何以同步整流器为基础的DC／DC转换器不带散热器还比传统的以肖特基二极管为基础的转换器带散热器能产生更多有用的输出功率。文章首先分析当DC／DC转换器的散热器被拆除后会损失多少“散热”能力。然后阐述较之低效率的传统转换器而言，以同步整流器为基础的转换器需要散发的热量少了多少。最后，文章比较两种转换器的功率降额曲线(derating curves)，以说明同步整流转换器因为高效率的所得胜过因为拆除散热器而受到的损失。     

Cost effective second generation AC-modules: Development and testing aspects

In the framework of the European research project PV2GO, a new AC-module inverter was developed, taking into account all relevant aspects from a European market's point of view (standards, market, application, and research and development goals). The project goal was to achieve the overall system costs of 3 Euro per Wp for a modular plug-and-play photovoltaic system. For the photovoltaic-module, a standard 130-Wp Eurosolare module was chosen. The research and development (R&D) goal was to develop an advanced DC-control system consisting of a state-of-the-art programmable digital device and an Application Specific Integrated Circuit (ASIC) for the AC-control of the inverter. According to the topology concept, thermal and magnetic designs were optimized with regard to production technology and packaging for large-scale production. The new AC-modules were tested in a number of field-test sites in various parts of Europe and their reliability was assessed through Highly Accelerated Stress Tests. Efficiency and power quality have been tested in the laboratory. Further in the PV2GO project an optimization study of the manufacturing process of the new generation of AC-modules for high volume output was done. Another task was the pre-certification procedure to assure compliance with the European guidelines and standards.     

Perverse Spite: The Possessive Gleam in the Mother's Eye and the Struggle to Own One's Soul: Reply to Stern (2004).

In this response to Jeffrey Stern's (2004) (see record 2004-21113-016) commentary on my article, "Giving the Devil His Due: Spite and the Struggle for Individual Dignity" (P. Shabad, 2000) (see record 2000-00917-004), I suggest that in emphasizing the conscious vindictiveness of explicit spite, Stern minimizes the perverse aspects of "cutting off one's nose to spite one's face" as a means of avenging oneself against powerful others. The underlying impetus of perverse spite is to break free from the prison of subtle developmental contingencies and unconscious seductions surrounding maternal possessiveness. When the child's self-assertive strivings are blocked because of the shame and fear of premature separateness, the inward obsessional churning of resentment becomes a fertile ground for perverse spite. (PsycINFO Database Record (c) 2010 APA, all rights reserved)