平原型城市总体城市设计的理论与方法研究探索——郑州案例

在中国快速和巨量城镇化进程中,城市正不同程度上经历着空间急剧拓展和街区肌理的剧烈变化,呈现在大尺度空间形态上,则体现为结构形态的尺度变化和显著外拓,平原型城市的普适性问题尤为突出。本文以郑州总体城市设计为样本,通过梳理平原型城市的国际规划理论和实践,对其整体空间形态的影响要素进行分析,尝试提出总体城市设计中平原型城市的空间形态规划理论和设计方法,以应对此类城市发展过程中典型的增长边界、城市骨架、结构模型等关键问题。     

单向载荷作用下向心关节轴承球铰节点的受力性能

在对3种型号向心关节轴承的径向和轴向破坏加载试验的基础上,采用ABAQUS有限元模拟节点各部件之间的接触关系,得到向心关节轴承球铰节点在径向或轴向单一载荷作用下的力学性能、受力特点、破坏模式和破坏机理.结果表明,满足额定载荷要求的向心关节轴承球铰节点具有良好的转动和承载性能,可应用于建筑工程中.     

Fibrous monolithic ceramic with a single alumina phase: Fracture and high-temperature tribological behaviors

Fabrication of fibrous monolithic ceramic with bamboo-like structures is a promising method to improve the mechanical properties of ceramics through extrinsic reinforcement. Nevertheless, heterogeneous boundaries are easily oxidized at high temperatures, which seriously limits the long-term use of these materials when employed in high-temperature and high/low-temperature alternating environments. In this study, a “plain” ceramic—a single-component and complex-structure Al₂O₃ ceramic—was successfully designed and prepared using nano-sized Al₂O₃ as polycrystalline fibers and micro-sized Al₂O₃ as boundaries to obtain a structure with a fibrous monolithic architecture. Self-toughening of Al₂O₃ ceramics can be achieved by introducing hierarchical architectures derived from the difference between grain sizes of fibers and boundaries, which gives the ceramics high fracture toughness and reliability. Moreover, the material demonstrated a low friction coefficient and high wear-resistance properties when coupled with C/C composites at room temperature, 800°C, and in the alternating temperature enviroment between room temperature and 800°C.     

基于分形理论的滑动轴承故障诊断研究

针对滑动轴承异常振动时振动信号的无规则特性和分形维数对时域振动信号的敏感性,将分形理论应用于风机滑动轴承故障诊断,分析了不同程度的接触摩擦状态与分形维数关系,揭示了接触摩擦越严重分形维数越大的规律,将其应用于故障诊断,取得了良好的效果,为滑动轴承故障诊断提出了一种新方法。研究表明:将该方法应用于矿山机械故障诊断领域具有重要的现实意义。     

平原灌区田间渠道量水计研制

对内蒙古河套灌区量水系统的总体方案、工作原理和量水计的标定方法作了简介；着重介绍引黄灌溉用水中含沙量高、水草漂浮物多等恶劣的水流条件下仪器的总体布局、工作原理和结构上采取的特殊设计．本量水计适用于平原灌区，也可用于一般灌区，以及环保部门对工业污水的现场监测．     

SO2 heat exchanger failure

Critical heat exchanger components are usually manufactured from durable steels, such as stainless steel, which exhibit good strength and corrosion resistance. Failure of a heat exchanger occurred due to specification of a plain carbon steel that did not survive service in the SO₂ vapor environment. However, failure analysis showed that cavitation erosion was the responsible failure mechanism, not corrosion as might be expected.     

Factors Influencing Impingement of Fish by Lake Ontario Power Plants

Fish impinged by two Lake Ontario power plants were examined to determined the causal factors. Fish were near shore because they resided there, migrated there to spawn or forage, or because the water mass in which they resided moved near shore. Once near shore, fish abundance in impingement collections was correlated with demersal or pelagic behavior. Periodic increases in diversity and abundance of impinged fish corresponded with times of upwelling and thermocline oscillations. These data suggest that some species were segregated along temperature gradients and were impinged when the thermocline passed near the intake. Comparisons of impingement catch between two power plants, one withdrawing a constant volume of water and the other a varying volume, showed that responses of fish to an intake were of three kinds. Alosa pseudoharengus and Osmerus mordax were apparently attracted to water currents entering the intake. Morone americana, Morone chrysops, Dorosoma cepedianum, and Perca flavescens were not influenced by changes in flow rate, suggesting that their impingement was proportional to their density in nearshore water. Micropterus dolomieui avoided the intake at higher flow rates in part due to rheotactic behavior.     

张先词之“三影”探析

北宋词人张先被人誉为“张三影”,其小令清新可喜,疏秀平易,特别善于运用“影”字营构画面,生动鲜活,亲切可感。张先词作使宋初词坛焕然一新,在中国词史上具有一定的影响。     

松嫩平原平展型和紧凑型玉米品种根系分布特征

采用土柱模拟栽培法与大田试验相结合的方法，对松嫩平原不同株型玉米的根系分布特征进行了比较。研究发现，平展型玉米和紧凑型玉米根干重最大值出现的时期不同，二根干重分别在吐丝后15d和吐丝后30d时达到最大值。成熟时紧凑型玉米根干重比平展型高12.2%。二根系垂直分布有明显的差异，在20cm以下的根干重比率，平展型玉米在19％以下，而紧凑型玉米高于23％。紧凑型玉米的深层根量较多，在深40－100cm土层内根干重比率比平展型高42.3%。二的根系水平分布也不同，紧凑型玉米根系水平分布较集中，在距植株0－10cm水平范围内，根系分布比率比平展型玉米高9.6%。紧凑型玉米土壤深层根量较多，水平分布集中，耐密植，是易获得高产的重要原因之一。     

真丝纺类织物计算机辅助设计软件研制

本文以真丝纺类织物实际可织区域作为该类织物计算机辅助设计的理论支持,建立了按织物重量要求,确定织物经纬纤度、密度和缩率等主要规格参数的计算方法,并给出了CAD应用软件的程序框图和运行结果.