Noise generated by multiple-jet nozzles with conical profiles 287

Conical multiple-jet nozzles, which reduce the risk of nozzle openings being blocked, are tested for their effectiveness in noise reduction. Nozzles with different exit spacings are tested. It is found that the multiple-jet design significantly decreases noise levels in the audible range by shifting emitted sound power to higher and ultrasonic frequencies. No significant difference in noise characteristics between exits distributed on a flat plane and beveled exits on a conical surface is observed. When the exits are more densely distributed, there is a trend of spectra shifting back toward the low frequency. This phenomenon is found to increase sound levels in a certain range of frequencies much lower than the peak one. Although this increase contributes little to the total emitted sound power, it is an important factor in determining the sound levels of audible noise.     

粉尘在巷道中的紊流传递分析

建立的粉尘在巷道中的传递方程是一个二维平流扩散输运方程。在巷道顶底板为吸收壁的条件下，导出了粉尘浓度分布函数。传统的工业沉降室沉降效率公式（横向混合模型）只是论文所列方程的一个特例。降低紊流强度和减小紊流扩散系数和纵向弥散系数均可提高沉降效率     

重力作用下尘粒运动的数值解法

提出了重力作用下尘粒运动的数值解法。依据尘粒的重力、浮力及所受到的阻力推出了尘粒自然沉降时的运动方程。当尘粒的运动在斯托克斯领域内时采用理论公式求解其运动轨迹,当尘粒的运动进入非斯托克斯领域内时,提出了修正斯托克斯公式的方法以达到用理论公式来近似模拟该领域内的尘粒自然沉降运动     

Multiple impact pathways of the 2015–2016 El Niño in coastal Kenya

The 2015–2016 El Niño had large impacts globally. The effects were not as great as anticipated in Kenya, however, leading some commentators to call it a ‘non-event’. Our study uses a novel combination of participatory Climate Vulnerability and Capacity Analysis tools, and new and existing social and biophysical data, to analyse vulnerability to, and the multidimensional impacts of, the 2015–2016 El Niño episode in southern coastal Kenya. Using a social-ecological systems lens and a unique dataset, our study reveals impacts overlooked by conventional analysis. We show how El Niño stressors interact with and amplify existing vulnerabilities to differentially impact local ecosystems and people. The policy significance of this finding is that the development of specific national capacities to deal with El Niño events is insufficient; it will be necessary to also address local vulnerabilities to everyday and recurrent stressors and shocks to build resilience to the effects of El Niño and other extremes in climate and weather.Electronic supplementary materialThe online version of this article (10.1007/s13280-020-01321-z) contains supplementary material, which is available to authorized users.     

Glazed tiles manufactured from incinerated sewage sludge ash and clay

Sewage sludge incineration is applied extensively in highly populated cities as a final sludge treatment. In this study, incinerated ash was utilized as an additive to clay to manufacture glaze tiles. Four different amounts of ash (0, 15, 30, and 45%) were added, and five glaze concentrations (0.03, 0.06, 0.1, 0.15, and 0.2 g/cm2) were applied on the surface of biscuit tiles to study the effects of ash additive and glaze concentration on properties of fired samples. Sewage sludge was dehydrated and incinerated into ash at 800 degrees C. Subsequently, tile specimens were manufactured and fired at 800 degrees C to make biscuit tiles. Fritted glazes and iron oxide were used as the fundamental glaze and colorant, respectively. Finally, glaze was applied on the surface of biscuit tiles and then fired at 1050 degrees C to sinter them into glazed tile specimens. Tests were performed to analyze properties, including water absorption, firing shrinkage, weight loss on ignition, abrasion resistance, bending resistance, acid-alkali resistance, and aging resistance on specimens of glaze tile. To further understand more about the microstructural behavior of glazed tile specimens, analysis of energy dispersive spectrometer, scanning electron microscopy, and X-ray were carried out in this study.