Conservative Wetting and Drying Methodology for Quadrilateral Grid Finite-Volume Models

Algebraic equations relating fluid volume and the free surface elevation in partially wetted quadrilateral computational cells are derived and incorporated into a Godunov-type, finite-volume, shallow-water model. These equations make it straightforward to reconstruct the free surface elevation based on the volume of fluid in a computational cell, the dependent variable tracked by finite volume models for conservation purposes, regardless of whether the cell is fully or partially wetted. Improvements to the variable reconstruction process streamline the computation of mass and momentum fluxes with approximate Riemann solvers, yielding a model that simulates sub-, super-, and transcritical flows over irregular topography with wetting and drying fronts. Furthermore, the model is free from fluid and scalar mass conservation errors and it eliminates nonphysical distributions of scalars by avoiding artificial concentration and/or dilution at wet/dry interfaces. Use of this wetting and drying methodology adds roughly 10% to the execution time of flow simulations.     

某压延厂房柱基下沉的调查与分析

压延车间厂房柱基础在施工阶段出现了大面积的不均匀沉降，本文通过现场踏勘，对地质勘察报告的分析，试桩资料的分析、降水方案和沉降观测记录的分析，找出了柱基础下沉的主要原因是欠妥的人工降水引起砂层的压缩固结，造成桩尖刺入持力层带动柱基础的下沉。     

Effect of Electro-Osmotic Dewatering on the Quality of Tofu Sheet

As a new dewatering technology with high efficiency and energy saving, electro-osmotic dewatering can be applied to food processing. The objective of this work was to study the effect of combined field dewatering (CFD) involving electro-osmosis and mechanical pressure on the quality of tofu sheet. Combined field dewatering was performed on the dewatering process of tofu sheet for 10 to 30 min at a voltage ranging from 30 to 50 V under various pulse-time ratio (t₊ = 120 s, t_- = 5 s) electric field and 0.047 MPa pressure field. The texture and structure of tofu sheet after treatments were examined by a rheometer and scanning electron microscope (SEM). The result showed that the three quality indexes, i.e., hardness, tensile strength, and ductility of tofu sheet near the anode were 45%, 30%, and 12% higher respectively than those dewatered by common mechanical pressure method. However, those near the cathode were 15%, 25%, and 10% lower respectively. When the electric field was applied for 10 min at 30 V, these indexes reached their maximum values. Meanwhile, the tofu sheet structure near the anode was more compact and homogeneous than that near the cathode. The result indicated that CFD could enhance the quality of tofu sheet.     

炼油厂“三泥”中污油的处理工艺研究

炼油厂“三泥”浮渣经沉降池初步脱水后,浮到上层的污油内部含有大量的水、污油和少量的污泥,稳定性好,进一步脱水很是困难,是炼油厂废物处理的难点之一.采用破乳、离心、减压蒸馏等方法处理炼油厂“三泥”的污油,并确定了破乳剂,最佳的破乳条件和离心条件.研究结果表明,该工艺不仅脱水效果显著,而且能回收大量燃料油.破乳条件为醚型表面活性剂“9901”和含硅型表面活性剂“SAE”的复配物0.10g,无水碳酸钠0.10g,搅拌时间15min.离心条件为分离时间10min,转速2500-4000r/min.     

深基坑开挖降排水设计

主要介绍了深圳地铁××车站深基坑开挖所采用的管井井点降水方案的设计情况。由于深圳地区浅部土层分布较为均匀 ,层位稳定 ,故介绍的方法具有一定的普遍性。     

Stop Logs for Emergency Spillway Gate Dewatering

Emergencies resulting in uncontrolled flow through spillway gates often lead to millions of dollars lost to repairs, lack of dam productivity, property damages, and risks to public health and safety. A considerable need exists for reliable emergency dewatering systems to prevent these consequences. Stop logs are the most commonly used dewatering system for spillway gates but are typically designed for maintenance purposes only. They have been found in most cases to be unreliable for emergency closure under flowing conditions. Considering the economic advantages a dewatering system would provide were it functional for the dual purposes of maintenance as well as emergency closure, a new stop log design was developed. This study assesses the design that enables deployment under no-flow conditions as well as flowing, or emergency conditions. The information found in this study provides dam owners, operators, and engineers with options to reduce damages resulting from uncontrolled releases owing to partial or complete failure of spillway gates, including the failure of gates to close after having been raised.     

二元结构含水层降排水设计施工探讨

为保护建筑场地的原始环境,针对不同属性的地下含水层制定不同的降排水方案,浅部孔隙型潜水的处理方法以止降结合的疏干排水为主,深部承压水则采用减压井来控制地下水水头,同时在降水过程中辅以多种监测手段。施工阶段则要严格按设计要求进行成孔、下井管、填滤料、封孔、洗井、预降水,降水井运营期间要做好井的保养维护,做到控制性的按需降水。     

交流变频调速装置在脱水系统中的应用

概述脱水系统原设计调速方案的弊端,并具体介绍交流变频调速装置的性能及系统改造方法.