Estimating the probability of fish encountering a marine hydrokinetic device

Strong tidal currents in eastern Maine, USA, make that region attractive for tidal power development. Little is known about the effects of marine hydrokinetic (MHK) devices on fish, yet many fish species use tidal currents for movements. We used empirical data from stationary and mobile hydroacoustic surveys to examine the probability that fish would be at the depth of an MHK device and may therefore encounter it. The probability was estimated using three components: 1) probability of fish being at device-depth when the device was absent; 2) probability of fish behavior changing to avoid the device in the far-field; and 3) probability of fish being at device-depth in the near-field when the device was present. There were differences in probabilities of fish encountering the MHK device based on month, diel condition and tidal stage. The maximum probability of fish encountering the whole device was 0.432 (95% CI: [0.305, 0.553]), and the probability of fish encountering only device foils was 0.058 (95% CI: [0.043, 0.073]). Mobile hydroacoustics indicated that fish likely avoided the device with horizontal movement beginning 140 m away. We estimated the encounter probability for one device, but results can be applied to arrays, which may have bay-wide implications.     

劣弧半径的测量工装

提出了对劣弧半径测量的必要性,并介绍了一种新的采用工装测量来计算劣弧半径的方法,而且对此工装的测量和公式的依据进行了详细的解释及推导,这种测量方式可在工厂的实际应用中得到推广。     

气动工具的噪声防治

气动工具在我国机械制造等各行业广泛应用的同时,工作时的排气噪声对周围环境也造成了一定的污染。介绍了治理噪声所采用的消声装置及设计方法,通过消声后的试验数据及噪声频譜对比分析,用正交试验法解决功率与噪声的矛盾,通过这种方法使噪音降低最大,功率损耗最小,这种消声装置原理治理噪声效果显著。     

Passive mixing control for innovative air diffusion terminal devices for buildings

This paper presents an innovative concept for optimized air diffusion in buildings. The method uses passive control of air jet through lobed diffusers. An analysis is done experimentally at different scales for a lobed shaped geometry. A cross-shaped jet is characterized first through an isolated orifice and then at the scale of one perforated panel. An intermediary analysis of two coalescent and a row of cross-shaped jets is also proposed. All the results lead to the same conclusion. The lobed diffuser favors the self-induction compared to a reference conventional circular perforated diffuser. The air flow induced in the case of the lobed perforated panel is in average twice as the one of the circular perforated panel. Despite the consequent gain in air induction for the lobed perforated panel flow, the streamwise maximum velocities display comparable values in the far field which signifies comparable throws for the two flows. Consequently, the presented lobed perforated panel concept can be generalized to different type of diffusers to improve mixing ventilation in buildings.     

On the electrochemical migration mechanism of tin in electronics

Electrochemical migration (ECM) of tin can result in the growth of a metal deposit with a dendritic structure from cathode to anode. In electronics, such growth can lead to short circuit of biased electrodes, potentially leading to intermittent or complete failure of an electronic device. In this paper, mechanistic aspects of ECM of tin are discussed in detail, using experimental results on ECM of tin in various environments and varying potential bias. Results on the formation of local pH changes by the electrodes and experiments observations are combined with thermodynamic stability of tin species as depicted in the Pourbaix diagram.     

发挥安全自动装置在工厂电力系统中的重要作用

针对乌石化电力系统安全自动装置的重要性及存在的问题,提出改进措施,最大限度的发挥其作用.     

Measurement and calculation of neutron densities in BWR high burn-up fuels

A neutron-scanning device was developed for measuring accurate neutron densities of BWR high burn-up fuels up to 65 GWd tU⁻¹. Characteristic test of this device was done with a ²⁵²Cf source and adopted to measure axial distributions of neutron densities of BWR spent fuels with various enrichments (2.0–3.4%), which had been irradiated up to 60 GWd tU⁻¹ at Fukushima Daini Nuclear Power Station Unit 2(2F-2). We found the measured neutron densities were proportional to about fourth power of the corresponding burn-up values. The neutron densities calculated by the ORIGEN2.1 code and various cross section libraries showed good agreements with the measured ones in profile and absolute value except for BWR-UE file mainly based on ENDF/B-IV. The BS240J32 library based on JENDL3.2 was the best among the investigated libraries.     

3200m^3／h真空变压吸附富氧装置的运用

通过介绍贵阳特殊钢有限公司新建成的3200m^3/h真空变压吸附装置的基本原理，工艺流程以及设备在炼钢上的应用，比较了吸附法相对深冷法的优越性。     

大型电瓷套管坯件数控喷釉装置速度控制研究

本文对大型高压电瓷套管坯件数控自动喷釉装置的工作原理和利用软件方法实现变速控制的数学模型、控制算法及控制程序进行了分析研究,给出了一个实用的解决方法。     

电磁装置非线性动态过程的数值计算

本文阐述了一种直接耦合模型。可以用于分析由电压源激励的电磁装置中二维非线性暂态磁场,提出了计算电磁装置动态特性的有关数值方法。在这方法中,对机械运动、涡流、激磁电路和磁性材料的非线性问题进行了综合考虑。这一直接耦合方法可用于求解暂态磁场。采用将非对称系数矩阵转化为对称带状加边矩阵的数值技术可以大大减少所需计算机存储量和CPU时间。文中给出了对制动电磁铁的应用实例。