隧洞开挖网络进度的优化研究

本文以单项工程为研究对象,以隧洞工程为例,研究了单项工程施工所需用的时间。文中以施工单位所具有的资源,结合施工工作环境、作业空间为约束条件,以费用最小为目标函数,建立了优化模型。由资源的工作性能指标,利用模糊数学原理,对资源间的匹配程度作了定量分析,并进一步推出了不同匹配程度的资源对作业时间的影响的计算式。并从影响各工序完工时间的因素的随机性出发,利用数理统计理论,由各工序的细分活动的规律推出了各工序的完工需用时间的概率表达式,解决了工期与置信度间的关系。最后结合工程实例,求出了一定置信度下,不同资源供应时的最优工期。     

基于滑动窗口的影像中建筑物特征提取方法研究

针对多尺度分割算法在工程项目应用中使用成本高的问题,提出采用基于滑动窗口的影像对象获取方法.将主成分第一分量作为输入,通过灰度共生矩阵计算影像对象纹理特征,并与光谱均值特征构建面向对象的建筑物信息提取方法,将多尺度分割后的预测结果与滑动窗口分割后的预测结果进行对比实验验证.结果表明,滑动窗口提取结果的总体精度比多尺度分割提取结果的总体分类精度高出0.94％,Kappa系数高出0.0125,验证了滑动窗口预测结果的准确性与普适性.     

Betel Nut Arecoline Induces Different Phases of Growth Arrest between Normal and Cancerous Prostate Cells through the Reactive Oxygen Species Pathway

Prostate cancer (PCa) is a reproductive system cancer in elderly men. We investigated the effects of betel nut arecoline on the growth of normal and cancerous prostate cells. Normal RWPE-1 prostate epithelial cells, androgen-independent PC-3 PCa cells, and androgen-dependent LNCaP PCa cells were used. Arecoline inhibited their growth in dose- and time-dependent manners. Arecoline caused RWPE-1 and PC-3 cell cycle arrest in the G2/M phase and LNCaP cell arrest in the G0/G1 phase. In RWPE-1 cells, arecoline increased the expression of cyclin-dependent kinase (CDK)-1, p21, and cyclins B1 and D3, decreased the expression of CDK2, and had no effects on CDK4 and cyclin D1 expression. In PC-3 cells, arecoline decreased CDK1, CDK2, CDK4, p21, p27, and cyclin D1 and D3 protein expression and increased cyclin B1 protein expression. In LNCaP cells, arecoline decreased CDK2, CDK4, and cyclin D1 expression; increased p21, p27, and cyclin D3 expression; had no effects on CDK1 and cyclin B1 expression. The antioxidant N-acetylcysteine blocked the arecoline-induced increase in reactive oxygen species production, decreased cell viability, altered the cell cycle, and changed the cell cycle regulatory protein levels. Thus, arecoline oxidant exerts differential effects on the cell cycle through modulations of regulatory proteins.     

A simple and effective process for fabrication of Gd0.1Ce0.9O1.95 solid electrolyte ceramics

Ce_0.9Gd_0.1O_1.95 ceramics were prepared using a simple and effective process in this study. Without any prior calcination, the mixture of raw materials was pressed and sintered directly. The reaction of the raw materials occurred during the heating up period by passing the calcination stage in the conventional solid-state reaction method. More than 99.5% of theoretical density was obtained for Ce_0.9Gd_0.1O_1.95 sintering at 1500–1600 °C. Fine grains (<1 μm) formed in pellets sintered at 1450 °C. The homogeneity of grains increased with the sintering temperature. The grains grew to >4.5 μm in pellets sintered at 1600 °C. The reactive-sintering process is proved to be a simple and effective method in preparing Ce_0.9Gd_0.1O_1.95 ceramics for solid electrolyte application.     

Deposition effects of WC particle size on cold sprayed WC-Co coatings

The WC particle size and its influence on the deposition of Co-based cermets are examined. Micron and nanostructured powders with similar Co content were employed. Varying the WC particle size influenced significantly the deposition efficiency of the coating process. Micrometer-structured WC-Co feedstocks did not permit coating build up when processed under comparable or elevated thermal spray parameters used for the nanostructured WC-Co feedstocks. In addition, micrometer-structured WC-Co coatings exhibited a conjoint erosion and deposition effect on the surface. Fine WC particles (< 1 μm) were observed near the substrate interface and larger WC particles (1-2 μm) in the vicinity of the coating surface. These observations indicate the existence of a critical WC particle size for deposition by the cold spray method and that the size criteria arises due to the formation and cohesion mechanisms within the coating layer.Nanostructured test specimens displayed (i) a dense microstructure with little presence of porosity, (ii) a crack free interface between the coating and substrate that indicated good adhesion, and (iii) no observable phase changes. The XRD patterns of each powder and their respective coatings did not have observable peak differences but the diffraction peak broadening of coatings indicated that there was grain refinement during the coating process. Furthermore, all nanostructured as-sprayed WC-Co coatings exhibited Vickers hardness values above HV1000. The nanostructured WC-Co coatings demonstrated adhesive strengths that exceeded the limits of the glue (60 MPa).     

Antibacterial Property of Cold Sprayed Chitosan-Cu/Al Coating

The antibacterial behavior of CS-Cu (chitosan-copper complex) powder and their composite coatings were investigated against Escherichia coli (DH5α). CS-Cu powder and Al (aluminum) based CS-Cu composite powders were synthesized using in-house powder processing techniques. The results indicated that the antibacterial effect of all the powders increased with the proportion of CS-Cu powder. These composite powders were subsequently used as feedstock to generate antibacterial coatings via cold spray technology. The ratios of CS-Cu to Al in their composite powders were 25:75, 50:50, and 75:25 (wt.%). Microstructural characterization and phase analysis of feedstock powders and as-deposited coatings were carried out using FESEM/EDX and FTIR. Antibacterial composite CS-Cu/Al coatings were successfully deposited using cold spraying parameters of 6-8 bars at preheated helium gas, temperature between 140 and 150 °C. The coatings retained the antibacterial properties of the original feedstock powders.     

基于GBDT算法的机器人定位误差分级补偿方法

为进一步提高工业机器人的定位精度,提出一种分级补偿的方法以降低几何和非几何因素引起的定位误差。使用遗传算法优化最小二乘法（GA-LS）进行几何参数误差辨识并补偿到机器人运动学模型中,再通过梯度提升树（GBDT）算法对残余非几何参数误差进行预测,并对残余误差进行补偿,最后以UR10机器人为研究对象进行了实验,验证该方法的准确性。实验结果表明：此分级补偿方法能有效提高机器人的绝对定位精度,补偿后机器人的平均定位误差由2.381 mm降低至0.156 mm,定位精度提升了93.4%;均方根定位误差由2.417 mm降低至0.163 mm,定位精度提升了93.2%。实验结果验证了此分级补偿方法的有效性。     

Unperturbed dimensions and the g factor of a star-shaped polystyrene

Unperturbed dimensions of a star-shaped polystyrene near the θ temperatures, 25°C, 35°C and 45°C were determined by the measurement of intrinsic viscosity of the polymer in poor solvents. It was found that the inferred mean square radius of gyration of the star-shaped polystyrene, while much smaller than that of the linear polystyrene, as expected, changes much faster with the increase of temperature. The geometric factor g of the star-shaped polystyrene was found to be temperature-dependent.