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21.
工业用地是城市建设用地的主要类型之一,是海绵城市建设的重要区域。通过梳理工业项目硬化面积高、径流污染程度高等特征,针对性提出其海绵城市建设的实施路径、建设标准和技术应用等实施建议。工业项目的海绵城市设计应遵循因地制宜的原则,应合理布局绿地并建设海绵设施,通过精细化的标高设计进行径流组织设计;对于降雨径流污染严重的三类工业项目,其海绵措施应以雨水调蓄池(应急事故池)为主,严禁设置具有渗透功能的源头控制设施。对于三类工业项目,海绵城市所提出的年径流总量控制率的目标与事故池的环保要求基本一致,建议相关部门在制定(修订)的应急事故池设计标准时,其中的径流污染控制体积可与对应区域年径流总量控制率标准协同一致。 相似文献
22.
LIANG Yong ZENG Xiaoyan TONG Baiyun SI Zhongyao Institute of Metal Research Academia Sinica Shenyang China LIANG Yong Professor Institute of Metal Research.Academia Sinica Shenyang China 《金属学报(英文版)》1990,3(11):330-334
The effect of the laser processing parameters on the composition uniformity and shapecoefficient of fusion zone with laser surface alloyed Cr plated on medium carbon low alloysteel has been studied.It was found that the composition uniformity depends on the shapecoefficient of fusion zone,and the later is a function of both power density and interactiontime.If the power density is fixed to a certain value,the shape coefficient is directly,propor-tional to the interaction time.A completely,uniform molten pool can be obtained,when theshape coefficient is between 1.6 and 3.0. 相似文献
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摘 要:针对中型拱坝下游消能防冲形式的选择问题,通过物理模型试验,对比分析了长护坦防护、水垫塘+二道坝和短护坦先冲后护三种布置形式下相应的水力学指标。试验结果表明:长护坦方案时,水垫塘内水流流态较差,底板和护岸易失稳破坏;水垫塘+二道坝方案时,水流流态和各项水力学指标满足要求,但水垫塘和二道坝的造价较高;短护坦先冲后护方案时,冲坑位置及深度均在允许范围内,该方案的应用会受到拱坝下游地质条件的制约。依据短护坦先冲后护的试验成果,提出初步确定短护坦防护范围的方法。本工程下泄的单宽流量较小,根据试验成果及类似工程经验,并结合坝址地质和工程造价因素,推荐消能工布置方案为“短护坦先冲后护”方式。 相似文献
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Liquid propylene was polymerized in a 5‐L autoclave batch reactor using a commercially available TiCl4/MgCl2/Al(ethyl)3/DCPDMS Ziegler–Natta catalyst, with a phthalate ester as internal electron donor. The powders from these polymerizations were characterized using laser diffraction particle size distribution (PSD) analysis, scanning electron microscopy (SEM), and bulk density measurements. These characteristics were analyzed as a function of the process conditions, including hydrogen and monomer concentration, polymerization temperature, and the prepolymerization method. It was shown that polymerization temperature influences the powder morphology to a large extent. At low temperatures, high‐density particles were obtained, showing regular shaped particle surfaces and low porosities. With increasing temperature, the morphology gradually was transferred into a more open structure, with irregular surfaces and poor replication of the shape of the catalyst particle. When using a prepolymerization step at a relatively low temperature, the morphology obtained was determined by this prepolymerization step and was independent from conditions in main polymerization. The morphology obtained was the same as that observed after a full polymerization at temperature. Even when using a short polymerization at an increasing temperature, the morphology was strongly influenced by the initial conditions. The effect of variation in hydrogen concentration supported the conclusion that the initial polymerization rate determines the powder morphology. In the absence of hydrogen, high bulk densities, and regularly shaped particles were obtained, even at high temperatures. With increasing hydrogen concentration, the reaction rates increased rapidly, and with that changed the morphology. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1421–1435, 2003 相似文献
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以局部表面改性的紫铜直方柱和梯度方柱阵列为研究对象,实验研究了表面润湿性、表面形貌和表面活性剂对池沸腾换热性能和气泡生长特性的影响。实验工质为去离子水,浓度分别为100、200、400、800 mg·L-1的异丙醇溶液和正庚醇溶液。实验结果表明:方柱阵列表面镀银之后润湿性变差,表面产生的气泡数量减少。向去离子水中添加异丙醇或正庚醇后,在热通量为66.1~202 kW·m-2时,气泡脱离直径变小、数目减少,而当热通量增至413 kW·m-2时,活性剂能够有效阻碍气泡合并,故池沸腾传热系数随着浓度增加先减小后增大。上下层宽分别0.5 mm和1 mm、间距为2 mm的梯度方柱阵列结构有助于气泡的合并,但由于促进了固体表面气膜的形成,从而降低了沸腾换热性能。 相似文献
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大流量水电站的消能设计历来都是非常复杂和困难的.在1:60溢流坝表、中泄水孔断面模型上对密松水电站泄水建筑物的布置方案进行了泄流能力、流速流态、压力分布等相关水力学问题的试验研究,并通过10多个方案的比较优化,提出了基本可行的泄水建筑物体型和消力池型式.研究成果表明:表孔取消宽尾墩,采用跌坎式消力池方案,可有效降低底流消能时的池底板流速,同时消除宽尾墩形成的水翅击打两侧导墙现象,达到了较满意的消能效果.试验成果对该工程设计提供了较好的参考方案,并对类似工程有很好的启发借鉴作用. 相似文献
30.
Safety evaluation and the static-dynamic coupling analysis of counter-arched slab in plunge pool 总被引:1,自引:0,他引:1
The stability of plunge pool slab of drainage structure is crucial to energy dissipation, but the working conditions of counter-arched
slab are very complex and its stress procedure is considerably nonlinear and coupling. Therefore, a nonlinear static and dynamic
coupling method to analyze the counter-arched slab configuration is put forward, which can reflect the coupling of dynamic
loads, slab, anchor bars, groundwork and abutment as well as the dynamic procedure of instability. Various nonlinear factors
and static-dynamic coupling are taken into consideration, and the working conditions, stress mechanism, dynamic instability
procedure and influential instability factors are revealed. The proposed method thus provides a comprehensive safety evaluation
method of plunge pool, which further provides an important theoretical basis for engineering design of counter-arched slab
in plunge pool.
Supported by the National Science Fund for Distinguished Young Scholars (Grant No. 50725929) and the National Natural Science
Foundation of China (Grant Nos. 50539060, 50679052, 50779044) 相似文献