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101.
The transport of thermal energy in thermodynamics is described as the product of entropy flow and of the absolute temperature, in analogy to the volume flow and pressure in oil hydraulics and to electric charge flow (= current) and voltage in electronics. Bond graphs are shown to be especially suitable to describe the splitting of applied thermal energy into internal energy and external mechanical work. Transformers and the 0- and 1-junctions of Paynter can illustrate various entropy flow processes, including Carnot engines and heat exchangers. Entropy flow in heat conduction is distinguished from entropy convection, or transport by moving mass, where the entropy/temperature characteristic or equation of state is important. Irreversibilities are represented by impedance transformers reducing temperature and increasing entropy flow but conserving power. 相似文献
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At-risk families’ control style (autonomy support and coercive control) was examined in relation to children's school readiness; children's social skills and mastery motivation were hypothesized mediating variables. In two different, low-income samples from diverse ethnic backgrounds, one preschool sample recruited from Head Start (N = 199) and a school transition sample composed of children entering elementary school (N = 344), parental control styles were related to children's academic readiness modestly but significantly in the preschool sample and weakly in the school transition sample. Children's social skills and mastery motivation skills (persistence and goal orientation) were significantly related to the academic measures of school readiness, and fully mediated the association between parents’ use of coercive behavioral control and academic readiness. Such mediation could not be tested for parental support of children's autonomy. The results indicate that a developmental cascade exists between parental control strategies and academic indices of school readiness, emphasizing the importance of family context models of school readiness. Furthermore, strong correlations between the domains of school readiness were found in both samples, reinforcing calls for a multidimensional approach to supporting school readiness in early childhood education programs. 相似文献
104.
This article estimates the effects of school expenditure on school performance at Key Stage 4 in England, over the period 2003–07 during which real per pupil expenditure increased rapidly. It adds to previous investigations by using dynamic panel analysis to: exploit time series data on individual schools that only recently has become available; adjust for the potential endogeneity not only of expenditure but also of other determinants of performance; and differentiate the short‐run and the (higher) long‐run attainment effects of spending changes. Consistent with other recent work, the article reports a generally significant but small effect of expenditure on school performance, but it also finds that the effect varies between specialist and non‐specialist schools, with the effect on the latter being larger. Further, the article identifies significant dynamics in the school improvement process, quantifies the long‐run effect of expenditure changes, suggests that spending effects increase with socio‐economic disadvantage, and quantifies absence effects. 相似文献
105.
Weiwei Yang Jiejunyi Liang Jue Yang Paul D. Walker Nong Zhang 《Journal of The Franklin Institute》2021,358(2):1214-1239
An hybrid uninterrupted multi-speed transmission (HUMST), based on the integration of a planetary gear set and a 3-speed automatic manual transmission (3-AMT), is developed to satisfy the specific performance indexes of mining trucks. The power-split device can alleviate and eliminate the inherent torque interruption of the 3-AMT during gear shift by implementing the designed cooperative shift control strategy which is optimized by quadratic performance index. In order to achieve fast torque coordination while guaranteeing the driving comfort performance, the torque profiles of the power split device and the traction motor are optimized by Linear-quadratic regulator (LQR) algorithm. Dynamic programming (DP) is implemented as a benchmark to demonstrate the maximum fuel efficiency of the proposed HUMST. Because of the high computational cost of optimal control strategies such as DP, an improved real-time control strategy (IRTCS) using modified Gaussian distribution function is proposed to significantly reduce the computing load. As efficiency-oriented energy control strategy would result in frequent gear shifts, to achieve a desirable tradeoff between the overall efficiency and the shift stability, multi-objective genetic algorithm (MGA) is integrated to optimize the overall performance. The detail mathematical and dynamic model shows that the proposed shifting strategy with LQR can effectively suppress shift jerk, and the proposed IRTCS with MGA can reduce shift frequency by 70.78% to improve the drivability, only sacrificing 4.86% of overall efficiency compared to that of DP. 相似文献
106.
In this paper, we lay out a relational approach for indexing and retrieving photographs from a collection. The increase of digital image acquisition devices, combined with the growth of the World Wide Web, requires the development of information retrieval (IR) models and systems that provide fast access to images searched by users in databases. The aim of our work is to develop an IR model suited to images, integrating rich semantics for representing this visual data and user queries, which can also be applied to large corpora. 相似文献
107.
Andrea C. Walker Rachelle Gewecke Illene N. Cupit Jeffrey T. Fox 《Journal of College Counseling》2014,17(2):131-149
This phenomenological study, based on ecological systems theory, examined the college student bereavement experience in a Christian university. Undergraduate students (N = 127) from a small Christian university provided answers to open‐ended questions about their experiences regarding college following a death loss. Results indicate that students are generally successful in adapting to bereavement and prefer an environment open to discussing death and asking difficult religious questions. Implications for counselors are provided. 相似文献
108.
Caroline Denaes Jean‐Louis Berger 《Journal of Research in Special Educational Needs》2014,14(2):82-95
Analogical reasoning involves the comparison of pictures as well as the memorisation of relations. Young children (4–7 years old) and students with moderate intellectual disability have a short memory span, which hampers them in succeeding traditional analogical tests. In the present study, we investigated if, by providing external memory hints, the visual aid could enable these participants to succeed in analogies comprising more relations than their memory span was able to manage. Our analogical test, composed of 2 × 2 matrices, was administered in two versions: the standard version, similar to traditional tests, required the participant to memorise all the relations involved in order to discover the solution, whereas the construction version required him/her to construct the answer part by part by using external memories, which potentially increased success by offloading the memory. Our results show that students with moderate intellectual disability reached results similar to typically developing control children when provided with external memory hints (referred to as external memories). Moreover, in the most complex levels of the test, they did not spend more time than control children in solving the analogies. 相似文献
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