航空倾斜摄影和三维激光扫描技术在古建筑修缮中的应用

由于年代久远,许多古建筑物缺少相关的图纸资料,在对古建筑进行修缮前,需要进行整体测绘.目前常用的测量方法存在着效率低下、获取信息量有限等情况.针对这些问题,使用三维激光扫描仪进行测量,三维激光扫描仪可以在短时间内获得大量的点云数据,但是三维激光扫描仪无法对房顶等盲区进行测量.因此,使用一种航空倾斜摄影与三维激光扫描技术相结合的方法来进行数据获取,通过将三维激光扫描点云与航空倾斜摄影点云进行转换、融合,即可以得到完整的建筑物点云数据.根据对应用案例进行分析,点云的精度满足绘图要求,融合点云能够满足设计的使用需求.     

尿基高氮肥生产工艺的影响因素

介绍了尿基高氮肥生产过程中出现的问题,分析了造粒温度、料浆温度、干燥温度以及造粒物料含水量和干燥物料含水量对尿基高氮肥生产的影响。通过合理调节温度和物料含水量,保证了装置的连续稳定运行,减轻了设备的结疤程度并降低了故障率,提高了装置的开车率。     

位置和角度对积分球测量LED成品灯的影响

由于LED光源发光的不均匀性,目前对LED及其成品灯的光色特性测量,仍没有有效的测试方法。文中将LED放在不同位置和中心不同朝向角度,采用积分球进行光色特性测量。然后采用分布光度计对同一LED/COB天花灯的相关光色特性进行测量。两种测试系统的测量结果表明,通过有效补偿,使用积分球快速测量LED成品灯的光色参数是可行的,并为其测试方法提出相关建议。     

自动弹仓回转选弹动力学仿真及优化

某大口径火炮弹药自动装填系统装备有链式回转自动弹仓,其回转选弹过程运行不平稳,冲击较多,受力状况复杂。基于多体动力学软件建立自动弹仓的虚拟样机模型,对回转选弹过程进行仿真分析,得到链轮的速度、位移和扭矩曲线,以及接触力变化曲线。结果表明,弹仓运动响应呈现出明显的周期性波动,弹仓回转受冲击较大;通过改进导轨设计和改变链轮连接方式,可有效减小冲击作用,对弹仓的优化设计有参考意义。     

Improvement of the input performance of a three-phase-single-phase matrix converter based on space vector modulation

A 6-switch three-phase to single-phase matrix converter (3-1MC) with independent neutral line is directly coupled to the input side through bidirectional switches, and the output ripple power produces low-frequency harmonics in the input side that are difficult to filter out. In this paper, the expressions of the frequencies and contents of the low-frequency harmonics are derived based on the principle of input-output instantaneous power conservation. Then, a 3-1MC topology with decoupling unit is studied and the working principle and process of improving the input performance are analyzed. Second, based on the relationship between the output side and the decoupling side modulation function, the influence of the introduction of the decoupling unit on the maximum voltage transfer ratio of 3-1MC is studied. The relationship between the voltage transfer ratio and parameters such as decoupling unit and output frequency is derived in detail. It is proved that maximum voltage transfer ratio of the topology is a nonlinear function related to system parameters. Then, the operating principle and modulation method of 3-1MC are discussed. A double-side current closed-loop control strategy based on space vector modulation under power decoupling conditions is proposed. Finally, an experimental platform is built to verify that the 3-1MC with decoupling unit can suppress the low-frequency harmonics in the input current at different output frequencies and effectively improve the performance of the input side. The results show that the 3-1MC with the decoupling unit is beneficial for use in single-phase applications.     

建筑保温用有机泡沫材料的发展与应用

泡沫塑料作为一种优质高效保温材料在我国建筑与工业保温中已逐步推广应用.本文较全面地介绍了国内外建筑与工业保温用有机泡沫材料的发展概况及材料性能,并着重介绍了泡沫塑料在我国建筑与工业保温中的生产与应用情况及存在问题.     

单晶纳米线TiO2光催化反应降解油田采出水中苯系物的研究

以单晶纳米线TiO2为催化剂,采用光催化氧化方法,对油田采出水进行处理,并对处理过程中苯系物的降解规律进行了研究.结果表明,经处理后废水中的苯、甲苯、对二甲苯、间二甲苯、邻二甲苯分别由1 276.0、432.3、183.1、1 319.4、324.3 μg/L降至70.6、14.6、7.7、24.5、6.3 μg/L,出水满足<国家污水综合排放标准>(GB 8978-1996)一级标准.     

纳米晶NiAl的机械合金化合成机理研究

采用机械合金化方法,以元素粉末为原料,对四种成分的NixA1100-x(x=25,30,40.50)进行不同球磨时间和球磨转速的机械合金化合成,制备纳米晶NiA1金属间化合物粉末.利用X射线衍射技术对球磨产物进行了物相分析,并对NiA1机械合金化合成机理进行了探讨.研究表明:NixAl100-x四种成分的元素粉末采用机械合金化方法均可以制备出纳米晶NiA1金属间化合物粉末;NiA1金属间化合物的机械合金化合成机理为燃烧合成反应.     

蓝晶石对低水泥耐火浇注料性能的影响

本文简单介绍了蓝晶石的结构、性能及应用范围,并结合试验,研究了蓝晶石加入量对矾土基耐火浇注料的体积密度、显气孔率、抗折强度和线变化等性能的影响。     

Preparation and properties of a nano TiO<Subscript>2</Subscript>/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> composite superparamagnetic photocatalyst

Nano TiO₂/Fe₃O₄ composite particles with different molar ratios of TiO₂ to Fe₃O₄ were prepared via sol-gel method. X-ray diffraction, transmission electron microscopy, and vibration sample magnetometry were used to characterize the TiO₂/Fe₃O₄ particles. The photocatalytic activity of the particles was tested by degrading methyl blue solution under UV illumination (254 nm). The results indicate that with the content of TiO₂ increasing, the photocatalytic activity of the composite particles enhances, while the magnetism of the particles decreases. When the molar ratio of TiO₂ to Fe₃O₄ is about 8, both the photocatalytic activity and magnetism of the TiO₂/Fe₃O₄ particles are relatively high, and their photocatalytic activity remains well after repeated use.