Analysis of switching devices with bond graphs

Modelling and simulation of switching devices with bond graphs is a subject which has no totally satisfying solutions. In this paper, switching devices are represented by flow or effort sources, with a variable circuit topology at switching time. For the simulation, the usual method uses causality resistors to insure integral causality to energy storage elements. The choice of those resistors is quite arbitrary and can lead to stiff systems. We propose, for linear systems, an approach without such resistors. When components lose the integral causality, the order of the state vector changes, provoking the use of pulse variables. A solution is proposed to compute the amplitude of the pulse and the value of the new variables.     

Questioning techniques to promote thinking

Research has shown that children as young as three and four can think on many different levels if they are encouraged to do so (Pepler & Ross, 1981; Turner & Durrett, 1975). Educators can promote young children's thinking by asking appropriate questions and by providing learning activities that require children to think beyond the recall or memorization level (What Works, 1986). Asking good questions is an art — an art that can be learned and refined with practice and with conscious effort.Jean M. Shaw and Mary Jo Puckett Cliatt are associate professors in the School of Education at the University of Mississippi in University, MS.     

Do increased resources increase educational attainment during a period of rising expenditure? Evidence from English secondary schools using a dynamic panel analysis

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.     

Effects of signaled reward in instrumental conditioning: Enhanced learning on DRL and DRH schedules of reinforcement

The effects of signaled reward were examined using DRL and DRH schedules of reinforcement. In each case, one group of rats received a brief cue between the reinforced response and the reward, and a second group received brief cues at random times. With the DRL schedule (Experiment 1), signaled reward decreased response rate, increased response efficiency (number of responses per reinforcer), and increased resistence to satiation relative to the control group. With the DRH schedule (Experiment 2), signaled reward increased response rate, efficiency, and resistance to satiation. These results refute an overshadowing explanation of the effects of signaled reward and suggest that food-correlated cues enhance learning of the reinforcement contingencies.