Sensitivity Analysis and Comparative Performance of Outfalls with Single Buoyant Plumes

This paper presents a new approach to analyze the performance of outfalls with single buoyant plumes in flowing ambient sea water, taking into account all three dilution mechanisms: the initial, the dispersion, and the effective dilution due to the decay of nonconservative substances. Simultaneous consideration of all dilution mechanisms, study of their functional relationships, sensitivity analysis of outfall behavior, and graphical presentation of the results, allows recognition of patterns of practical importance that remain otherwise obscure. The generated graphs afford an overview of the relative performance of outfalls with a single port and perpendicular line diffusers over a broad range of operating conditions, and portray the sensitivity of the single-port outfall behavior. The results show that, contrary to common belief, outfalls with a single port outperform those with perpendicular line diffusers over a broad range of operating conditions. They also show that higher rather than lower current speed is the critical factor in the design of single-port outfalls. These findings affect the construction cost of outfall systems and bear a significant impact on the sizing of new outfalls as well as on the performance evaluation of existing ones.     

Dissolution of Direct Ocean Carbon Sequestration Plumes Using an Integral Model Approach

We present the results of a double-plume integral model for a positively buoyant multiphase plume of liquid carbon dioxide injected at mid-depths (500–2000?m) in the ocean. In addition to the relevant plume physics, the model accounts for dissolution of the carbon dioxide droplets, the effect on dissolution of clathrate hydrate films, and the increase in seawater density due to enrichment by dissolved carbon dioxide. Due to the creation of negative buoyancy in the entrained fluid through dissolution of carbon dioxide, the near-field mixing exhibits a complex set of energetic descending outer plume structures that do not converge to a steady state. The unsteady near field is shown to be inherent in the plume physics, resulting in enhanced distribution of the dissolved carbon dioxide over the plume height and formation of multiple, unsteady intrusion layers. Despite the complex plume near field, we demonstrate that the height of maximum plume rise has a steady solution. A general empirical design equation for the maximum height of plume rise is presented from the model results, dependent on the initial droplet diameter and buoyancy flux, the strength of the ambient stratification, and the linear mass transfer reduction factor due to hydrate formation. A sensitivity analysis of the design equation highlights the droplet diameter as the most important design variable and demonstrates that current uncertainty in the value of the mass transfer reduction factor results in uncertainty of the plume rise height within a factor of three.     

Graphical Sizing of Small Single-Outlet Detention Basins in the Semiarid Southwest

A graphical procedure is presented for sizing single-outlet detention basins to control stormwater runoff from small catchments in the semiarid southwestern United States. The approach relies on the modified rational method to provide the catchment runoff hydrograph, a linearized relation between basin water depth and storage volume, and a rainfall-intensity-duration equation for which coefficients can be found easily for any location covered by NOAA Atlas 14, Volume 1 (Arizona, Southeast California, Nevada, New Mexico, and Utah). Numerical solutions of a dimensionless form of the differential detention storage continuity equation are carried out, and solution values are related to a dimensionless discharge coefficient that provides a comprehensive characterization of catchment hydrology, outlet structure type and size, and regional precipitation. Graphs that supply dimensionless values of the maximum peak outflow rate from a basin, the maximum storage volume, and the critical storm duration (that is, the storm duration that produces the peak outflow and maximum storage volume) are prepared from the numerical solutions. The method avoids repetitive calculations and provides accurate solutions rapidly in an uncomplicated way for small catchments of about 12 ha or less with times of concentration less than about 30 min.     

SP轧机运动状态分析

以上海宝钢1580热轧线上的SP定宽机为例,对SP轧机侧压模块的运动规律进行了理论分析与试验研究,给出了侧压模块的运动方程,计算了侧压模块的运动规律。通过对侧压模块运动状态的实测,分析了操作侧与传动侧侧压模块的同步关系、侧压机构与同步机构的相位关系及空载与轧制状态模块的动态特性。由试验结果可发现设备存在的问题,为设备维护与检修提供了依据。     

板坯定宽过程狗骨分布的有限元分析

利用有限元方法建立了板坯定宽的有限元模型 ,系统研究了板坯定宽过程中金属的流动规律 ,并模拟了板坯狗骨形成过程。得到狗骨的分布规律 ,对研究板坯定宽有重要指导意义。     

三辊定径机轧辊机架安装调整设计分析

介绍了三辊内传动和外传动两种型式定径机轧辊机架的辊缝、齿侧间隙和轴承游隙的调整设计及装配方法,分析了影响安装调整的关键尺寸公差的控制,为三辊定径机轧辊机架的设计提供了参考.     

Computer-Aided Graphical Analysis of Bridges under Vehicular Loading

A computer-based, graphical approach is presented to construct the Influence Profile for determinate bridge structures that are subjected to multiple axle loads. An Influence Profile represents the variation of an internal or external force, or moment, at a specific location of a structure, under loading by an actual vehicle (e.g., AASHTO HS-20 truck, American Railway Engineering and Maintenance-of-Way Association (AREMA) Cooper E-80 train). The technique works by scaling the influence line ordinates by the individual axle weights of the vehicle, and by applying distance delays to account for the horizontal separation between axles. The scaled and shifted influence lines for individual axle loads are then superimposed graphically to obtain the effect of the entire vehicle. Beam and truss examples are given to illustrate the technique. A simple method is also presented for constructing influence profiles for compound systems, where the load is transferred through the deck and floor beams to the superstructure. Because of its graphical concept, the technique provides a practical approach for evaluating the force effects caused by an actual vehicular load; it is also well suited for teaching purposes.     

关于石油套管定径轧制过程中残余应力的分析

在石油套管制造过程中,热轧无缝钢管制造的最后生产环节是定径工艺.此环节决定了石油套管的尺寸和几何形状,消除了石油套管轧制和热处理后的尺寸及圆度等误差,同时也影响其机械性能.分析了在符合石油套管的尺寸和圆度要求下,定径压下量与残余应力之间的关系、石油套管定径轧制时的变形规律,以便减小定径工艺所产生的残余应力,获得最佳的定径效果,提高石油套管的机械性能.     

SP轧制过程及侧压模块受力的测试研究及有限元分析

针对SP轧制过程,通过有限元模拟和现场测试认为,框架内部间隙、轧制负荷是引起模块振动、衬板受力不均和侧压不同步的主要原因,分析了轧制板坯头部和中间部位时板坯的变形规律和侧压模块的受力,给出了轧制狗骨的产生机理。同时定量模拟了当模块的垂直度出现偏差时产生向下分力的大小,这是加剧衬板损坏的一个原因。通过与实测结果的比较,证明建立模型的正确性和计算结果的可靠性。     

用有限元法分析板坯调宽过程中切头量的变化

采用ANSYS有限元分析软件，对宝山钢铁集团公司1580mm热轧厂调宽压力机的板坯调宽过程中板坯头部的变形规律进行了模拟计算；分析了调宽压力机的调宽步进量、侧压量及锤头起始位置等3种调宽参数条件下板坯切头量的变化规律；确定了获得最小切头量的最佳调宽参数。这些参数的提出对进一步探讨板坯调宽时板坯头部的变形规律、指导生产及提高成材率均具有一定的实际意义。     

大型进口风机的设计选型及应用

介绍了进口风机的结构特点，列举了设计选型的实例，分析了风机效率影响因素，指出选用进口风机需要考虑的因素。     

石油套管定径轧制残余应力的模拟分析

 在石油套管制造过程中,一般要采用定径工艺消除石油套管轧制和热处理后的尺寸及圆度等误差。这一热轧无缝钢管的最后生产环节决定了石油套管的尺寸和几何形状,同时也影响其力学性能。为此,研究了满足石油套管的尺寸和圆度要求下的定径压下量与残余应力之间的关系,进行了石油套管定径轧制时的变形规律分析,以便减小定径工艺所产生的残余应力,获得最佳的定径效果,提高石油套管的力学性能,为定径工艺的制定提供理论依据。     

大型进口风机的设计选型及应用

介绍了进口风机的结构特点,列举了设计选型的实例,分析了风机效率影响因素,指出选用进口风机需要考虑的因素。     

高线精轧及减定径辊箱进水分析及处理

分析精轧及减定径辊箱进水的原因和造成的危害,提出有效可行的处理措施,控制润滑系统的油品清洁度和含水量,确保摩根设备稳定运行。     

武钢烧结整粒系统三次筛箱梁故障分析及处理

针对四烧整粒筛分系统三次A、B直线振动筛箱梁反复出现开裂的现象,通过现场振幅测量分析,认为两筛所受激振力偏大、中间轴变形及箱梁本身结构等问题是引起箱梁开裂的主要原因.通过对激振器偏心块、中间轴及箱梁进行相应处理和改进,有效地解决了箱梁开裂问题,提高了设备作业率,确保了烧结机正常生产.     

Graphical Analysis of the State of Stress in Road Harrow Cutters

The conditions of using a software package for studying the state of stress in the cutting element intended for cold milling of a road coating are considered. The mechanism of designing a 3D model for the cutting element and the choice of failure criteria for the cutting element are described. The state of stress is subjected to graphical analysis at various loads.