材料参数对点面正碰撞的柔度关系影响研究

采用2D轴对称有限元法(FEA)模拟计算了弹性、理想弹塑性和幂指数应变强化弹塑性钢球与刚性平面碰撞.分析了影响柔度关系的各种因素.弹塑性碰撞的FEA结果说明塑性变形是导致能量损失的主要原因.研究结果为多体系统动力学计算提供了有益的参考.     

石油倾点自动测量仪

本文介绍了根据GB/T3535-1991的操作规范设计的测量仪,包括其测量原理、测量电路和温度测量校正的分析.     

A new deep spatial transformer convolutional neural network for image saliency detection

In this paper we propose a novel deep spatial transformer convolutional neural network (Spatial Net) framework for the detection of salient and abnormal areas in images. The proposed method is general and has three main parts: (1) context information in the image is captured by using convolutional neural networks (CNN) to automatically learn high-level features; (2) to better adapt the CNN model to the saliency task, we redesign the feature sub-network structure to output a 6-dimensional transformation matrix for affine transformation based on the spatial transformer network. Several local features are extracted, which can effectively capture edge pixels in the salient area, meanwhile embedded into the above model to reduce the impact of highlighting background regions; (3) finally, areas of interest are detected by means of the linear combination of global and local feature information. Experimental results demonstrate that Spatial Nets obtain superior detection performance over state-of-the-art algorithms on two popular datasets, requiring less memory and computation to achieve high performance.     

Quantitative feedback synthesis of sampled-data systems with time-delay by approximate Z-transform

In this paper, the equivalent disturbance rejection (EDR) in QFT design methodology is proposed for dealing with sampled-data systems with time-delay. This EDR is mainly to overcome the non-minimum phase zero generated by the first order Pade' approximation of the time-delay factor. Due to plant parameter uncertainty, the analogue controller is to be designed so that the system response lies within permissible bounds. By approximate Z-transform, the analogue controller can be transformed directly into a digital one and then the analogue plant is transformed into the digital plant, with sampling time as a free parameter. By adjusting the sampling time, the uncertain sampled-data system can be stabilized. In comparison with other approaches, our design framework is much more systematic by using only algebraic manipulations and transparent enough to guide the designer to realize the physical controller for the plant with prescribed bounds on its parameters.     

掺低熔点玻璃粉水泥胶砂的耐热性能研究

对掺低熔点玻璃粉水泥胶砂性能进行了研究.测试了不同煅烧温度前后试件的抗压强度和抗折强度,分析了强度残值率、脆性系数和微观结构.试验结果表明,低熔点玻璃粉能显著改善水泥胶砂在高温煅烧(900℃)时的耐热性能,提高强度残值率和降低脆性系数,尤其与粉煤灰或矿渣粉复掺时效果更好.当掺10％低熔点玻璃粉和15％粉煤灰时,抗压强度残值率改善幅度最高,达40％,抗折强度残值率改善幅度达48％,脆性系数最低,为5.63;掺10％低熔点玻璃粉和15％矿渣粉的水泥胶砂,抗压强度残值率为52％,抗折强度残值率为50％.     

Effect of cohesive powders on pressure fluctuation characteristics of a binary gas-solid fluidized bed

The effect of cohesive particles on the pressure fluctuations was experimentally investigated in a binary gas-solid fluidized bed. The pressure fluctuation signals were measured by differential pressure sensors under conditions of various weight percentages of cohesive particles. The cohesive particles increased the fixed bed pressure drop per unit height and decreased the minimum fluidization velocity. The Wen & Yu equation well predicts the minimum fluidization velocity of the binary system. The addition of cohesive particles slightly decreased the bubble size in bubbling flow regime when the cohesive particles and the coarse particles mixed well, while the bubble size greatly decreased when the cohesive particles agglomerated on the bed surface. The time series of pressure fluctuations was analyzed by using the methods of time domain, frequency domain and wavelet transformation. The normalized standard deviation of pressure fluctuations decreased with increasing weight percentages of cohesive particles. A wide bandwidth frequency of 0 to 1Hz got narrower with a single peak around 0.6Hz with an increase in proportion of the cohesive particles. The meso-energy and micro-energy of pressure fluctuations were decreasing with increasing cohesive particles proportions, which indicated that adding cohesive particles could reduce the energy dissipation of bubble and particle fluctuations.     

Stabilization of epoxidized soybean oil‐plasticized poly(vinyl chloride) blends via thermal curing with genistein

In an effort to alleviate the well‐known toxicity effect of phthalate derivatives on human health, genistein (G) modified epoxidized soybean oil (ESBO) has been investigated as an alternative “green” plasticizer for poly(vinyl chloride) (PVC) with potential application in medical products. As evidenced by a single glass transition that shifts systematically with composition in conjunction with the melting point depression of G crystals, ESBO is not only a good plasticizer to PVC, but also miscible with G. Moreover, ESBO is an excellent compatibilizer to the immiscible PVC/G pair. Furthermore, PVC/ESBO/G ternary blends revealed complete miscibility in the amorphous state. Of particular interest is that ESBO‐plasticized PVC is thermally curable with G at elevated temperatures above 220 °C and affords relatively stable G modified ESBO‐plasticized PVC for blood contact medical applications such as blood bags and hemodialysis tubings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46472.     

YG35/70型白乳胶自动充填包装生产流水线

用新思维设计自动充填包装生产流水线，解决了胶粘剂灌装难题，流水线主要由灌装体气缸阀总成，输送带，无级变速电动机，电器控制箱四部分构成。     

Transparent,Anisotropic Biofilm with Aligned Bacterial Cellulose Nanofibers

Cellulose nanofibrils are attractive as building blocks for advanced photonic, optoelectronic, microfluidic, and bio‐based devices ranging from transistors and solar cells to fluidic and biocompatible injectable devices. For the first time, an ultrastrong and ultratough cellulose film, which is composed of densely packed bacterial cellulose (BC) nanofibrils with hierarchical fibril alignments, is successfully demonstrated. The molecular level alignment stems from the intrinsic parallel orientation of crystalline cellulose molecules produced by Acetobacter xylinum. These aligned long‐chain cellulose molecules form subfibrils with a diameter of 2–4 nm, which are further aligned to form nanofibril bundles. The BC film yields a record‐high tensile strength (≈1.0 GPa) and toughness (≈25 MJ m^?3). Being ultrastrong and ultratough, yet the BC film is also highly flexible and can be folded into desirable shapes. The BC film exhibits a controllable manner of alignment and is highly transparent with modulated optical properties, paving the way to enabling new functionalities in mechanical, electrical, fluidic, photonics, and biocompatible applications.     

射频磁控溅射法制备GZO:Ti薄膜的微结构及其光学性质

采用射频(RF)磁控溅射工艺于玻璃衬底沉积了镓钛 共掺杂氧化锌(GZO:Ti)半导体薄膜,研究了沉积 温度对薄膜微观结构和光学性质的影响。通过X射线衍射仪(XRD)和紫外分光光度计对其晶体 结构和透射光谱特 性进行表征,同时利用光谱拟合法获取了薄膜的光学常数。研究结果表明,所有薄膜均具备 六角纤锌矿结 构和c轴择优取向特性,沉积温度对薄膜的微结构参数、光学 常数和光学带隙具有明显调控作用,当沉积 温度为653K时,GZO:Ti薄膜的晶粒尺寸最大(82.12nm)、位错密度最低(1.48×10－4 nm－2) 、微应变最小(0.001)、可见光区平均透射 率 最高(82.06%)及光学带隙值最大(3.57eV )。