Compressive sensing-based wind speed estimation for low-altitude wind-shear with airborne phased array radar

An important issue in low-altitude wind-shear detection is to estimate the wind speed of wind field. In this paper, a novel method for wind speed estimation with airborne phased array radar is proposed by combining space time adaptive processing and compressive sensing. The proposed method is able to achieve accurate wind speed estimate in the condition of limited number of sampling pulses, as demonstrated by numerical examples.     

Novel poly(3‐hydroxybutyrate) composite films containing bioactive glass nanoparticles for wound healing applications

Bioactive glass is considered an ideal material for haemostasis as it releases Ca²⁺ ions upon hydration, which is required to support thrombosis. In this study the effects of the presence of nanoscaled bioactive glass (n‐BG) in poly(3‐hydroxybutyrate) (P(3HB)) microsphere films on the structural properties, thermal properties and biocompatibility of the films were studied. The n‐BG with a high surface area was also tested for its in vitro haemostatic efficacy and was found to be able to successfully reduce clot detection time. In an effort to study the effect of the roughness induced by the formation of hydroxyapatite on cellular functions such as cell adhesion, cell mobility and cell differentiation, the composite films were immersed in simulated body fluid for periods of 1, 3 and 7 days. From scanning electron microscopy images, the surface of the P(3HB)/n‐BG composite microsphere films appeared fairly uniform and smooth on day 1; however on day 3 and day 7 a rough and uneven surface was observed. The presence of hydroxyapatite on the composite microsphere films on day 3 and day 7 influenced the surface roughness of the films. However, when the P(3HB)/n‐BG composite microsphere films with enhanced surface roughness were tested for biocompatibility, reduced amounts of protein adsorption and cell adhesion were observed. This study thus revealed that there is an optimal surface roughness for the P(3HB) microsphere films for increased cell adhesion, beyond which it could be deleterious for cell adhesion and differentiation. © 2016 Society of Chemical Industry     

Interactions among biomass components during co-pyrolysis in (macro)thermogravimetric analyzers

The interactions of biomass components (hemicellulose, cellulose, and lignin) during co-pyrolysis were investigated in a thermogravimetric analyzer (TGA) as well as a self-designed Macro-TGA with higher heating rate and larger amount of sample. The overlap ratio (OR) was used to evaluate the interaction of biomass components quantitatively. In TGA, the pyrolysis of xylan was not significantly affected by cellulose, whereas the pyrolysis of cellulose was markedly influenced by xylan. The interactions between xylan and lignin were weak with an overlap ratio of 0.9869, whereas co-pyrolysis of cellulose and lignin was strongly inhibited by interactions with the overlap ratio of 0.9737. In Macro-TGA, interactions between components were stronger than that in TGA due to more considerable heat and mass transfer effect.     

一起220kV电容式电流互感器爆炸事故的分析

介绍了爆炸事故的简要经过和设备概况,为分析事故的原因对互感器进行了解体检查,结合解体检查结果,分析互感器设计制造工艺中存在的问题,分析事故原因和事故发展过程,并提出几点建议和预控措施。     

基于RBF神经网络的FeO-MnO渣系ZGMn13堆焊焊条的设计

为设计一种ZGMn13堆焊焊条,提出了一种基于RBF神经网络的FeO-MnO渣系焊条配方优化设计方法.利用试验采集的数据对网络进行训练,以加工硬化后的硬度为优化目标,得到最优的焊条配方.试验结果表明:优化后熔敷金属的动载加工硬化性能和静载加工硬化性能良好.     

夜间通风在不同气候条件下的适用性

近年来,夜间通风作为一种被动式降温手段受到越来越多的关注。为了研究夜间通风在中国不同气候条件下的节能效果,选取北京、上海、广州分别作为寒冷地区、夏热冬冷地区以及夏热冬暖地区的代表城市,使用建筑能耗模拟软件Energyplus建立一个办公建筑模型,分别在使用和未使用夜间通风的情况下计算出3个城市建筑在供冷季各月的供冷能耗和总能耗,通过对比,分析夜间通风的节能效果。研究结果表明,在相同的月份,夜间通风的效果会随着城市纬度的增加而增大,但对于整个供冷季,即便是在低纬度的夏热冬暖地区,夜间通风也具有显著的节能效果。     

Effects of Carbon and Oxygen Impurities on Luminescence Properties of BCNO Phosphor

The BN and BCNO phosphors were prepared at 750°C using different methods and their structure and luminescent properties were investigated. All the prepared samples were turbostratic boron nitride structure. The SEM and high‐resolution TEM images show that the BCNO phosphors are polycrystalline in nature and include some nanocrystals. The carbon and oxygen impurities have great effects on the excitation, emission, and absorption spectra of BN and BCNO phosphors. The first‐principle calculations results indicate that the carbon and oxygen impurities will produce energy levels in the band gap, which can affect the spectra properties of BCNO phosphors. The spectra properties of BN and BCNO phosphors can be well explained by a simplified energy level diagram.     

Mechanical Behavior of Diamond-Sawn Multi-Crystalline Silicon Wafers and its Improvement

Poor mechanical property is identified as a potential barrier to commercial development of diamond wire sawn multi-crystalline silicon wafers. 3-point bending tests of the diamond-sawn multi-crystalline silicon wafer samples, along with those of mono-crystalline silicon and of the slurry-sawn wafers for references, were carried out. The bending in two orthogonal orientations relative to the cutting marks was tested respectively. Critical strain at breakage is chosen to indicate the wafer’s strength against breakage in bending. Effective elastic moduli of the different wafer samples in bending were also measured. The results show that, compared to slurry-sawn silicon wafers, diamond-sawn silicon wafers, either of mono-crystalline or multi-crystalline, are stronger in the direction parallel to the cutting marks, and weaker in the direction vertical to the cutting marks; more importantly, for diamond-sawn multi-crystalline silicon wafers, a very low critical strain level, ～57 % of the slurry-sawn multi-crystalline silicon wafers, is identified, in their direction vertical to the cutting marks. In view of the relevance of the critical strain to the breakage rate for the main stream slurry-sawn wafers, this would cause an unacceptably high breakage rate in industrial production and application of the diamond-sawn multi-crystalline silicon wafers. Annealing was found to significantly raise the critical strains of various wafers, and encouragingly, annealing at temperature as low as 400 °C can raise the critical strain of the diamond-sawn multi-crystalline silicon wafers to a level similar to that of the slurry-sawn multi-crystalline silicon wafers.     

试论建筑施工质量管理

提高建筑施工质量管理水平,是保证工程质量的重要手段。本文先点出加强建筑施工管理的重要性,再分析建筑施工质量管理过程中存在的问题,并提出相应的措施。