点线啮合齿轮冷胶合计算研究

根据弹性流体动力润滑理论,运用道森和希金森公式计算点线啮合齿轮各啮合点最小油膜厚度及膜厚比以估计齿面间的润滑状态,判别是否产生冷胶合.推导啮合点的综合曲率半径计算公式,确定啮合点单位齿宽法向载荷.根据点线啮合齿轮实际发生冷胶合的位置,确定了最小油膜厚度计算点,并根据大量实际计算提出修正后的最小油膜厚度计算公式.     

长大距离下的洗车机无人值守技术改造

广州地铁二十一号线各场段配置的洗车机洗车作业仍采用有人值守的方式,人员工时利用率低.针对广州地铁二十一号线各场段的实际情况,对长大距离下洗车机无人值守功能改造进行了研究,提出了通过光纤通讯进行远程监控的方案,对二十一号线各场段配置的洗车机进行安装改造,实现无人值守洗车,有效提升了工作效率,降低了人力成本.     

Minimizing bromate formation with cerium dioxide during ozonation of bromide-containing water

This work investigated the effect of several metal oxides including alpha-FeOOH, alpha-Fe(2)O(3), gamma-FeOOH, and CeO(2) on bromate formation potential (BFP) during ozonation of bromide-containing water. Results indicate that CeO(2) could most effectively minimize the BFP among these metal oxides taking ozonation alone as control. The BFP minimization by O(3)/CeO(2) favored a relatively low Br(-) concentration (i.e., <1.0mgL(-1)) and pH<7. Water temperature ranging from 5 to 25 degrees C had no significant impact on the percent reduction of BrO(3)(-). Further investigation indicates that the effective BFP minimization can be ascribed to neither the surface adsorption of BrO(3)(-) or Br(-) on CeO(2) nor the surface reduction of BrO(3)(-) to HOBr/OBr(-) by CeO(2). It seems to have relationship with the activity of surface Ce(IV) sites. The CeO(2) can lower the concentration of H(2)O(2) which is formed during ozone decomposition and promotes BrO(3)(-) formation. Another possible reason for the BFP minimization is that the CeO(2) could possibly reduce BrO() to HOBr/OBr(-) during the decomposition of H(2)O(2).     

美国建筑的奠基者安德鲁·杰克逊·唐宁

安德鲁·杰克逊·唐宁通常被誉为美国景观建筑和园艺学的鼻祖。在这种耀眼光环的笼罩下,唐宁作为美国乡土建筑奠基者的身份却被有意无意地忽视了。本文通过分析唐宁的相关著述和设计实践,展现他对美国建筑所作的历史贡献以及对人类理想居所作的探索。     

公共卫生事件视角下的健康城市 ——《死亡地图》的启示

新冠病毒的全球蔓延对健康城市提出了新的挑战,从公共卫生事件视角重新思考健康城市的本质与需求,有利于进一步探索未来健康城市的规划途径和方向.《死亡地图》[1]记录了1854年伦敦经历霍乱肆虐的详细过程,此书对于疫情常态化之下如何建构健康城市具有较大的启示,在结合实时数据和案例分析的基础上,重新思考健康城市,包括:多维度的评估体系、可视化技术的关键方法、韧性内核等问题,将为后疫情时代的健康城市研究厘清思路和方向.     

中国近代建筑的"中国观"初探

该文通过质疑这种目前仍然有着巨大影响的“欧洲中心论”,认为将用来评价中国近代建筑所得出的结论是站不住脚的,评价中国的近代建筑的标准不应该是“欧洲中心论”,而应该立足于中国近代建筑发展的特殊条件,建立起一种新的客观的评价标准——“中国观”,并对中国近代建筑“中国观”的内涵进行解释和论证。     

送风口对传染性隔离病房室内定向气流的影响

本文分析了送风口对传染性隔离病房室内定向气流的影响，指出在要求形成定向气流的场合，应综合考虑送风口的位置、形式与特性。采用CFD模拟与实验测试的方法，利用相关评价指标，在特定气流分布方式的隔离病房中，选取三种典型的送风口进行研究，从而得出了适合形成定向气流的送风口形式。模拟和实验发现，在采用天花板顶送风和异侧下排气流分布方式的隔离病房中，选用送风自由度较大的双层百叶送风口，调节百叶到合适的角度可实现较为理想的病房气流分布。     

Characteristic analysis on temporal evolution of floc size and structure in low-shear flow

A series of flocculation tests were performed to investigate the effect of low-shear rates (G = 3-16 s⁻¹) on flocculation of kaolin suspension by polyaluminum chloride (PACl), with the goal of understanding floc growth mechanisms. Results were reported in terms of floc average size (d_p) and boundary fractal dimension (D_pf), derived from a non-intrusive optical sampling and digital image analysis technique. As expected, the rate of floc aggregation increased with increasing G, resulting in faster changes in aggregate size and structure in the initial stage of flocculation. Nevertheless, steady state was attained faster for D_pf than for d_p at the same shear rates, possibly due to the self-similarity of fractal aggregates. An interesting finding was that at G = 3 s⁻¹, an obvious plateau was observed for the average-size evolution at steady state; for shear rates of 6 and 7 s⁻¹, the flocs exhibited some decrease after reaching the peak of size, mainly as a result of floc settling at steady state; and for G = 11-16 s⁻¹, a decrease in floc size was possibly attributed to the irreversibility of PACl-floc breakage. The process of floc growth was described using a fractal growth model, which defined flocculation as the result of the combined processes of aggregation and restructuring. The conceptual model could effectively characterize temporal changes in floc size and structure, and found that fragmentation followed by reformation seemed to be more effective in forming larger and more compact aggregates than the restructuring process due to erosion and reformation, which may provide useful insights for the design of flocculation reactors.     

医疗卫生体系改革与城市医疗卫生设施规划

通过分析城市医疗卫生体系改革对于城市医疗卫生设施配置规划的影响,对城市医疗卫生设施的概念和配置指标的内涵进行了全新的诠释。寻求新时代条件下,城市医疗卫生设施规划的科学研究方法和空间布局模式,并提出相关政策的建议。     

含沙量对分离鳃的水沙分离影响试验

为研究含沙量对分离鳃水沙分离效果的影响,通过对分离鳃与普通管进行9组不同含沙量的静水沉降试验,运用粘性颗粒的沉降特性分析了含沙量与沉速的关系。结果表明,含沙量对泥沙沉速影响很大,含沙量越大,泥沙下沉相同距离时所需的沉降时间越长,泥沙的沉速越小;在同一含沙量下分离鳃的沉速始终大于普通管沉速,当含沙量为10~80 kg/m3时,分离鳃沉速更大,水沙分离效果最佳。