曲轴扭转振动和发动机噪声的关系(译文)

概述 本文介绍了日本ISUZU内燃机有限公司对一台已进行声学处理的柴油机幅射噪声机理的实验结果。与按常规设计的柴油机相比,这台发动机的总噪声级虽已相当低,因为通过对发动机结构的改进,使在人听觉的重要范围800～1250Hz内的噪声降低到令人满意的程度。但现在,主要的噪声峰值出现在1/3倍频程315Hz及1600Hz处,这两个峰对总噪声级     

OpenCL: A Parallel Programming Standard for Heterogeneous Computing Systems

We provide an overview of the key architectural features of recent microprocessor designs and describe the programming model and abstractions provided by OpenCL, a new parallel programming standard targeting these architectures.     

辉光显示装置在电梯楼层指示中的应用

辉光显示装置在电梯楼层指示中的应用李维諟，周云仙随着高层建筑的兴起，电梯自然成为不可缺少的重要设施。电梯楼层指示，传统均采用灯箱式，即一长排灯箱，每位数字后面安一个灯泡，需指示那一层，则在该层数字后面将灯泡点燃。这种方式看似简单，实则成平并不低而且无...     

相变墙体在节能建筑中的应用

在充分考虑北方地区夏季昼夜的气候条件和国家节约用电的峰谷电价差政策的基础上,利用DSC进 行了相变储能材料性能测试与分析,优选出2种脂酸类相变材料制成相变储能墙板,进行了相变墙板热性能 分析。研究表明,相变墙体在北方寒冷地区节能建筑中应用,可以利用我国北方城镇丰富的自然冷风条件,符 合国家有关调低乡镇居民电价和电力移峰填谷政策,不但能降低供热空调系统的投资与能耗,而且也是一种 改善建筑能耗对环境负面影响的有效途径。     

Sampled-data filtering framework for cardiac motion recovery: optimal estimation of continuous dynamics from discrete measurements

Quantitative and noninvasive estimation of cardiac kinematics has significant physiological and clinical implications. In this paper, a sampled-data filtering framework is presented for the recovery of cardiac motion and deformation functions from periodic medical image sequences. Cardiac dynamics is a continuously evolving physical/physiological process, whereas the imaging data can provide only sampled measurements at discrete time instants. Given such a hybrid paradigm, stochastic multiframe filtering frameworks are constructed to couple the continuous dynamics with the discrete measurements, and to coordinately deal with the parameter uncertainty of the biomechanical constraining model and the noisy nature of the imaging data. The state estimates are predicted according to the continuous-time biomechanically constructed state equation between observation time points, and then updated with the new imaging-derived measurements at discrete time instants, yielding physically more meaningful and more accurate estimation results. Both continuous-discrete Kalman filter and sampled-data Hinfinity filter are applied for motion recovery. While Kalman filter is the optimal estimator under Gaussian noises, the Hinfinity scheme can give robust estimation results when the types and levels of model uncertainties and data disturbances are not available a priori. The strategies are validated through synthetic data experiments to illustrate their advantages and on canine MR phase contrast images and human MR tagging data to show their clinical potential.     

Hamilton-Jacobi skeleton on cortical surfaces

In this paper, we propose a new method to construct graphical representations of cortical folding patterns by computing skeletons on triangulated cortical surfaces. In our approach, a cortical surface is first partitioned into sulcal and gyral regions via the solution of a variational problem using graph cuts, which can guarantee global optimality. After that, we extend the method of Hamilton-Jacobi skeleton to subsets of triangulated surfaces, together with a geometrically intuitive pruning process that can trade off between skeleton complexity and the completeness of representing folding patterns. Compared with previous work that uses skeletons of 3-D volumes to represent sulcal patterns, the skeletons on cortical surfaces can be easily decomposed into branches and provide a simpler way to construct graphical representations of cortical morphometry. In our experiments, we demonstrate our method on two different cortical surface models, its ability of capturing major sulcal patterns and its application to compute skeletons of gyral regions.     

Tunable Terahertz Source Based on Optics Pumped Nonlinear Crystals

Recent progresses about optical pumped tunable terahertz （THz） sources are interviewed, including THz parametric oscillation （TPO） and difference frequency generation （DFG）. We develop high efficiency and high power surface-emitted TPO, as well as DFG with nonlinear crystals. A novel scheme for the high efficiency DFG source based on the Cherenkov phase-matching technology is comprehensively investigated in both bulk crystals. The widely tunable optical THz radiation is also researched based on the organic nonlinear 4-N,N-dimethylamino-4＇-N＇- methylstilbazolium 2,4,6-trimethylbenzenesulfonate （DSTMS） crystal.     

STUDY ON THE AIRFLOW RESISTANCE IN NATURAL DRAFT COOLING TOWERS

A new approach for improving the calculation of the airflow resistance coefficient of natural draft cooling towers from the inlet to throat (4) has been presented in this paper. The suggested equations areWhere. ζ1 is the coefficient of the airflow resistance with no consideration of waterdrop in rain zone, ζ2 is the coefficient of the airflow resistance due to falling of waterdrop in rain zone, s is the rate of the inlet area to the area at elevation of the packing, q is the water loading, V0 air velocity at the packing section.     

Investigation of the enhancement fluorescence of ethanol doped SiO2 nanoparticles

As one of the most commonly used solvents, ethanol exhibits weak fluorescence when excited by ultraviolet (UV) light. Until now, the fluorescence of ethanol-doped nanoparticles has not been studied. In this paper, eleven different concentrations of SiO2 nanoparticles (diameter 100 nm) were doped in ethanol, and corresponding colloids were formed. The excitation and emission spectra of the colloids were measured. The experimental results indicated that the SiO2 nanoparticles obviously enhanced the fluorescence of ethanol. Under excitation at 306 nm, the enhancement effect is the best when the concentration of SiO2 nanoparticles is 4.452 x 10(12) ml(-1), and the enhancement factor is nearly 50 times at the peak position of 360 nm. At the excitation wavelength of 360 nm, the enhancement effect is the best when the concentration of SiO2 nanoparticles is 1.113 x 10(13) ml(-1), and the enhancement factor is nearly 40 times at the peak position of 397 nm. The result of this article will reduce the test limit of ethanol by two magnitudes.     

High-performance single CdS nanowire (nanobelt) Schottky junction solar cells with Au/graphene Schottky electrodes

High-performance single CdS nanowire (NW) as well as nanobelt (NB) Schottky junction solar cells were fabricated. Au (5 nm)/graphene combined layers were used as the Schottky contact electrodes to the NWs (NBs). Typical as-fabricated NW solar cell shows excellent photovoltaic behavior with an open circuit voltage of ～0.15 V, a short circuit current of ～275.0 pA, and an energy conversion efficiency of up to ～1.65%. The physical mechanism of the combined Schottky electrode was discussed. We attribute the prominent capability of the devices to the high-performance Schottky combined electrode, which has the merits of low series resistance, high transparency, and good Schottky contact to the CdS NW (NB). Besides, a promising site-controllable patterned graphene transfer method, which has the advantages of economizing graphene material and free from additional etching process, was demonstrated in this work. Our results suggest that semiconductor NWs (NBs) are promising materials for novel solar cells, which have potential application in integrated nano-optoelectronic systems.