Effect of bulk flow pulsations on film cooling with compound angle holes

Experiments are conducted to investigate the effects of bulk flow pulsations on film cooling with compound angle holes. A row of five film cooling holes is considered with orientation angles of 0°, 30°, 60°, and 90° at a fixed inclination angle of 35°. Static pressure pulsations are produced by an array of six rotating shutter blades, which extend across the span of the exit of the wind tunnel test section. The pulsation frequency is fixed at 36 Hz, but changes in the time-averaged blowing ratios of 0.5, 1.0 and 2.0 produce three different coolant Strouhal numbers, 3.6, 1.8 and 0.9, respectively. Detailed film cooled boundary layer temperature distributions are measured by a cold wire and the adiabatic film cooling effectiveness by thermochromic liquid crystal (TLC). The boundary layer temperature surveys show that pulsations induce large disruptions to the boundary layer temperature distribution and the film coverage. As the orientation angle increases, the injectant concentration spreads further into the spanwise direction because of pulsations than the steady case. With pulsations the adiabatic film cooling effectiveness value decreases regardless of the orientation angle. The amount of reduction, however, depends on the orientation angle in such a way that the larger the orientation angle is, the smaller the reduction is.     

Working memory and articulation rate in children with spastic diplegic cerebral palsy.

A. D. Baddeley, N. Thomson, and M. Buchanan (1975) suggested that articulatory rehearsal rate determines the amount of verbal material that can be maintained in working memory. In the current study, 12 children with spastic diplegic cerebral palsy (SDCP) and 38 normal children were tested on measures of articulation rate and memory span for 1-, 2-, and 3-syllable words. Across all conditions, articulation rate for the SDCP group was significantly slower than for the normal group; nonetheless, memory span was equivalent for both groups. This finding implies that covert rehearsal proceeded normally for the SDCP group, in spite of decrements in speech rate. Thus, the relationship between overt and covert rehearsal rates differs for children with SDCP compared with normal children. Findings from the current study further suggest that normal speech rates are not necessary for development of normal covert rehearsal rates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

莫来石材料的研究现状及其应用

较详细地介绍了莫来石的性能、生产、研究现状和用途。尤其对多元复合莫来石韧性陶瓷及莫来石超细粉末的制备进行了评述,同时展望了莫来石作为高级陶瓷材料的发展前景。     

Controller for digital audio power amplifier with bit stream input

A new controller for a digital audio amplifier with bit stream input is proposed. The proposed controller has excellent features such as wide error correction range and no limitation on the modulation index. The controller is implemented in the half-bridge class-D amplifier and performance is verified through experiments.     

液氮温区同轴脉冲管制冷机的实验研究

脉冲管制冷机冷头朝上布置可以使制冷机与超导器件的耦合更方便 ,但对G -M型脉冲管制冷机 ,重力会对这种布置方式产生不利影响。对双向进气型脉冲管制冷机 ,直流和耦合传热会共同影响脉冲管制冷机的性能。介绍了液氮温区G -M型同轴脉冲管制冷机的实验结果 ,主要研究了蓄冷器温度分布和重力对脉冲管制冷机性能的影响     

Congestion pricing of multi-modal transportation systems

This paper deals with the pricing and investment decision problem of multi-modal transportation systems in which the congestion is a significant factor in the assessment of system costs. This study approaches this congestion pricing problem with a number of social welfare maximization problems, all of which have the identical structure except financial constraints. One welfare maximization problem examined in this study yields the pricing and investment decision, which can attain the first-best social optimality for multi-modal transportation systems. Other welfare maximization problems show he second-best optimal solutions that can address two policy questions in transportation economics, namely, the cross-subsidy between competing modes and peak-period congestion charges on a single highway link. Received: February 2001/Accepted: December 2001 This work was supported in part by funds from BK21 Research Division of Seoul National University for Social Infrastructure and Construction Technology.     

Recursive solution of inverse natural convection problems by means of mode reduction

 A recursive method based on the Kalman filtering is developed to solve inverse natural convection problems of estimating the unsteady nonuniform wall heat flux from temperature measurements in the flow. By employing the Karhunen–Loève Galerkin procedure that reduces the Boussinesq equation to a small set of ordinary differential equations, the computational difficulties associated with the Kalman filtering for the partial differential equations are overcome. The present method is assessed through several numerical experiments, and is found to yield satisfactory results. Received 20 January 2001 / Accepted 31 May 2001