分体空调器室外机钣金件动态特性分析及优化设计

本文针对某分体空调室外机低频异响问题,通过现代声振测试手段确定了钣金件与异响之间存在的关联,重点以钣金件为研究对象,通过对钣金件模态属性的测试,结合有限元分析,掌握了钣金件的动态特性,明确了其存在的问题缺陷,在不增加钣金件成本的前提下通过钣金件的局部结构修改对其模态属性等动态特性进行优化设计,修改后样机实验证明本文采取的结构修改措施可以显著改善钣金件声辐射性能,消除室外机低频异响。     

An in situ intercalative polymerization method for preparing UV curable clay–polymer nanocomposites

A novel in situ intercalative polymerization technique was used to disperse clay mineral in a precursor resin for use in UV curing by performing an in situ ion exchange reaction during polyesterification. Unmodified montmorillonite (MMT) was added to a reaction mixture composed of monomers and methyl, tallow, bis‐2‐hydroxyethyl ammonium (MTEtOH) during the synthesis of unsaturated polyesters to create resins containing highly dispersed, organically modified MMT. UV‐curable clay–polymer nanocomposite (CPN) films were then prepared utilizing donor–acceptor chemistry through reactions of the unsaturated polyester resin with triethylene glycol divinyl ether. Functional group conversion improved up to 15% by the incorporation of clay mineral into the polymer matrix through the in situ polymerization method. The CPNs also had improved barrier, mechanical, and thermal properties over a control film containing no clay mineral. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42601.     

基于Y型沸石的解聚制备ZSM-5/Y沸石催化材料

以工业NaY沸石在碱性环境下解聚形成的硅、铝物种作为ZSM-5沸石生长的部分原料,通过补加适宜的硅物种和模板剂等,成功得到了具有核-壳结构的ZSM-5/Y沸石催化材料。采用XRD、FT-IR、NH3-TPD、SEM、EDS等对合成的材料进行表征,并以异丙苯和正庚烷的催化裂化反应评价了该复合材料作为裂解催化剂的催化活性,并与对应的机械混合物比较。结果表明,ZSM-5/Y沸石复合物的形成是一个由Y型沸石向ZSM-5沸石转变的过程,后合成的ZSM-5沸石包裹Y型沸石进行生长,形成以多晶Y型沸石为核,ZSM-5沸石为壳的复合物。ZSM-5/Y沸石复合物与对应的机械混合物的性质存在显著差异,并非两种沸石的简单加和。与对应的机械混合物相比,ZSM-5/Y沸石复合物催化正庚烷裂化反应的正庚烷转化率更高,低碳烃,特别是乙烯和丙烯的选择性更高;催化异丙苯裂化时,异丙苯转化率较低,壳层的孔道结构是其主要影响因素。     

Seismic performance of corrugated steel plate concrete composite shear walls

In this paper, composite shear walls with different encased steel plates (flat, horizontal corrugated, and vertical corrugated) were tested and simulated by Abaqus to investigate the seismic behavior of corrugated steel plate concrete composite shear walls (SPCSWs). The failure characteristics, deformation and energy dissipation capacity, and stiffness and bearing capacity of the structures under low‐frequency cyclic load were analyzed, and indexes of the seismic performance were obtained. The formulas of the shear‐bearing capacity of steel plate concrete composite shear walls are suggested, and the shear‐sharing ratio of each member is obtained. According to the obtained results, corrugated steel plates can bond with concrete well, and the bearing capacity of the vertical corrugated SPCSW are higher than that of the horizontal corrugated SPCSW. Compared with flat SPCSW, corrugated SPCSW has higher initial stiffness and lateral stiffness, better ductility and energy dissipation ability, and the degradation of bearing capacity and stiffness is slower. The shear‐sharing ratio of a steel plate is larger than that of reinforced concrete in the flat SPCSW and the vertical corrugated SPCSW, the shear force shared by steel plate and reinforced concrete in horizontal corrugated SPCSW is basically the same.     

基于改进PSO-BP神经网络的冰蓄冷空调冷负荷动态预测模型

当前多数冰蓄冷空调冷负荷动态预测方法中,由于模型输入变量与输出结果相关性差、信息冗余度高等原因,导致多数预测模型在预测精度和收敛速度方面都未达到理想的预测效果,因此,提出一种改进的PSO-BP神经网络算法预测大型公共建筑的冷负荷。对于输入变量与输出结果采用灰色关联度分析,消除样本输入变量对数的耦合性,确定影响冰蓄冷空调系统冷负荷的关键性因素,将其作为输入变量,预测冰蓄冷空调系统动态冷负荷。结果表明：T时刻室外空气温度、T-1 h时刻室外空气温度、T时刻室外空气湿度、T时刻太阳辐射强度、T-1 h时刻太阳辐射强度、T-1 h时刻空调冷负荷是影响T时刻冰蓄冷空调系统冷负荷的关键因素,并以此作为预测模型的输入变量。相对于传统PSO-BP神经网络全输入变量预测算法,该模型预测结果精确度更高、收敛速度更快。     

基于YOLOv5和U-NET的多目标药盒抓取系统设计

目的 解决传统机器视觉机器人抓取系统对多目标及复杂目标背景分割不精确导致的目标定位精度差而影响机器人抓取效率的问题,提出一种新的深度学习抓取识别定位系统。方法 搭建由Delta机械臂、PC上位机、双目相机等组成的硬件系统,对工业部署常用的YOLO系列算法进行对比研究。将YOLO与U-NET相结合,用于目标的检测和分割。在精确分割出属于目标和背景目标的像素区域的同时,计算边缘和中心位置信息,运用立体视觉技术得到三维位置,并转换为世界坐标系,由PC机引导机械臂去完成抓取任务。结果 深度学习目标检测和图像分割相结合的系统在较复杂背景、多目标的场景下比未添加图像分割的算法拥有更好的目标定位精确度。结论 YOLOv5和U-NET相结合的目标定位抓取方法具有较高的鲁棒性,达到了并联机械臂的抓取要求。该方法能够运用于其他多自由度机械臂上,具有良好的应用价值。     

Video object segmentation by 2-D mesh-based motion analysis

Video object extraction is a key technology in content-based video coding.A novel video object extracting algorithm by two Dimensional (2-D) mesh-based motion analysis is proposed in this paper.Firstly,a 2-D mesh fitting the original frame image is obtained via feature detection algorithm. Then,higher order statistics motion analysis is applied on the 2-D mesh representation to get an initial motion detection mask.After post-processing,the final segmenting mask is quickly obtained.And hence the video object is effectively extracted.Experimental results show that the proposed algorithm combines the merits of mesh-based segmenting algorithms and pixel-based segmenting algorithms,and hereby achieves satisfactory subjective and objective performance while dramatically increasing the segmenting speed.     

Visible Spectra of Standard Navy Colored Flares

The visible spectra, color data and output powers from standard U.S. Navy red, green and yellow signal flares are presented. The spectra were taken under essentially identical conditions on actual inservice U.S. Navy devices. The dominant emissions accounting for the output power in the flares are from the molecular bands of the alkaline earth oxides, hydroxides and chlorides in the red and green flares and from atomic sodium in the yellow flare.     

蛋乳发酵工艺的研究

利用灭菌的蛋液中加入无菌的鲜乳,进行发酵,制成凝固型发酵蛋乳,通过实验确定蛋乳发酵的最佳工艺条件为发酵周期3.5 h,初始糖浓度为9%,蛋液加入量为8%,接种量为3%。