Treatment of Stagnant Zones in Riverine Advection-Dispersion

Advection-dispersion in streams encounters pockets of stagnant or dead zones in the flow, which trap the injected tracer. Treatment of stagnant or dead zones for dispersion is presented using one-dimensional advection-dispersion equation. A method is suggested for simultaneous estimation of dispersion coefficient, apparent (or effective) velocity, and effective injected mass of tracer, from a temporal concentration profile observed at a downstream section. The method is robust and uses a nonlinear optimization. Using the method procedure for estimation of adsorption coefficient for riverine advection-dispersion has also been suggested. The effective velocity is related to the stagnant zone fraction (average fraction of cross-sectional area attributed to stagnant zones) and adsorption. The application of the method on published data sets show that the parameter-estimates are reliable and the observed concentration profiles are closely reproduced. The analytical procedure described for the treatment of stagnant zones may have a wide application in civil engineering as well as other fields. The amount of chemicals released from the industrial units or by an accident can be estimated.     

Comparing Three Models for Treatment of Stagnant Zones in Riverine Transport

The modified advection dispersion equation (MADE) model is compared to the transient storage model (TSM) and fractional advection dispersion equation (FRADE) model for modeling riverine transport. The comparisons are illustrated using field examples. The parameter F of the FRADE model is found to be inconsistent to its physical meaning and is unrelated to dead zone fraction. Also, the estimated parameters of TSM are found to be inconsistent to their physical meaning. On the contrary, the parameters of MADE are consistent and related to the dead zone fraction. It is observed that the MADE model is easy to use and yields reliable and consistent results.     

深井开采中岩爆灾害研究思路及方法

通过对深井开采系统特征的分析研究，提出深井开采系统是一个典型开放的复杂系统。对这种系统的研究，目前行之有效的方法是采用从定性到定量的综合集成方法，将专家群体统计数据和信息资料、计算机技术三者有机结合起来，构成一个高度智能化的以人为主、人机结合的交互系统。通过集成各种知识，获得对问题正确的认识和理解，在工程实践中发挥具体的指导作用。文中详细地论述了岩爆灾害的研究方法及思路，对深井开采中的岩爆问题具有重要的理论及实践意义。     

Deep brain stimulation for movement disorders

Chronic deep brain stimulation (DBS) is a promising technique for the treatment of movement disorders. Thalamic stimulation is now an established surgical procedure for parkinsonian and essential tremor. Pallidal and subthalamic stimulation are under active investigation as treatments for Parkinson's disease. Although high-frequency DBS at these sites has similar behavioral effects as lesioning, the physiologic mechanisms underlying the beneficial effect of DBS is not well understood and may be extremely complex. DBS offers a potential advantage over ablative therapy because stimulation-induced complications are reversible, and the stimulation parameters are adjustable to minimize complications and maximize therapeutic effects. With this added safety, bilateral stimulation or use of a stimulator following a prior procedure may be preferable to bilateral ablative procedures.     

Deep brain stimulation for essential tremor

We examined the effects and safety of deep brain stimulation (DBS) as a treatment for essential tremor (ET). Ten ET patients with disabling medication-refractory tremor underwent stereotactic implantation of a DBS lead in the left Vim thalamic nucleus and completed a 6-month follow-up. The Clinical Tremor Rating Scale and disability assessments were performed at baseline, 1-, 3-, and 6-month follow-up. There were significant improvements in dressing, drinking, eating, bathing, and handwriting as reported by the subjects. Tremor severity, writing, pouring, and spiral and line drawing were significantly improved as rated by the examiner. Improvements persisted through the 6-month follow-up period. Although global disability significantly lessened in the group as a whole, one subject with hand-finger tremor accentuated by writing had no change in disability status. In this 6-month open-label study, DBS was effective and safe in reducing tremor and functional disability in ET.     

General Third-Order Solutions for Irregular Waves in Deep Water

The third-order analytical solutions for the strong interactions among three free-wave components are derived using two well-known perturbation methods, namely, the mode-coupling method and the Zakharov equation method. A term-by-term comparison of their solutions shows that the two methods render virtually identical results. The validity and convergence range of the solution are investigated for the interacting free-wave components of various frequencies but within the frequency range of storm seas. It is found that the solution may encounter two types of convergence difficulties, which occur, respectively, in the cases (1) when two of the interacting free-wave components are of quite different frequencies; and (2) when two of the interacting free-wave components are very close in frequency but the frequency of the third free-wave component is relatively larger or smaller.     

沙钢管线钢LF精炼的低成本深脱硫工艺

 根据沙钢对管线钢的生产需求及制造成本的控制,结合LF钢包精炼深脱硫的相关理论,开发了适用于管线钢的深脱硫精炼渣和低成本深脱硫工艺。使用该工艺,可完全不使用CaF2,只需使用石灰、铝脱氧产物和转炉下渣即可完成造渣,减少了石灰的消耗,降低了生产成本。180t LF生产实践表明:该工艺可将管线钢的硫含量稳定控制在10×10-6以下,精炼平均脱硫率高于85%。同时,该精炼渣具有较强的夹杂物吸附能力,精炼终点的非酸溶铝含量为（20~100）×10-6。     

RH用低碳深脱硫预熔渣

为实现低碳、超低碳钢在RH中进行深脱硫且钢水不增碳,在200kg真空感应炉上对RH用低碳深脱硫预熔渣进行了脱硫试验研究,结果表明:以CaO-Al2O3-SiO2-MgO为主的低碳深脱硫预熔渣熔点低、脱硫率高,可在真空条件下将钢液中硫的质量分数由30×10-6~50×10-6脱至10×10-6~20×10-6以下,脱硫率达到55%以上,脱硫效果好,脱硫率稳定。该预熔渣中碳的质量分数小于0.05%,在脱硫过程中钢水几乎不增碳,适用于在RH中低碳、超低碳钢深脱硫。研究表明:适当地提高炉渣的光学碱度,可大大地提高其硫容量,增强炉渣的脱硫能力。使用该预熔渣处理钢水有利于钢中夹杂物的去除和细化。     

RH精炼过程深脱硫的试验研究

实验室钢液真空脱硫试验表明,组成为６５％￣８５％石灰和１５％￣３５％萤石的粉剂,粒度为５ｍｍ以下,加入量在３￣８ｋｇ／ｔ的条件下,可使初始硫含量为０．００３５％￣０．００６５％的钢液脱硫至０．００２０％以下,脱硫时间为１０￣１５ｍｉｎ,脱硫率在６０％￣８０％。     

钢水深脱硫的方法

介绍了硫对高质量钢材的危害。通过对比工艺流程和成本指标，指出在生产超低硫钢时，钢水炉外精炼深脱硫的必要性，分析了钢水炉外精炼深脱硫的主要方法。     

深基坑土钉支护数值模拟

基于FLAC3D的基本原理及其求解过程，对深基坑工程土钉墙支护做了数值模拟，对不同土钉长度、倾角的4种支护方案进行了对比选择。对所选支护方案的计算结果进行分析，得出一些有用的结论，对深基坑土钉墙支护设计及合理施工有一定的指导意义。     

Lateral and Upward Soil-Pipeline Interactions in Sand for Deep Embedment Conditions

The soil–pipeline interactions in sand under lateral and upward movements are investigated with particular attention to the peak forces exerted on the pipe. The analytical solutions for estimating the peak forces are summarized and it is shown that, for deep embedment condition, there is large uncertainty in the true values since the bounds established by the analytical solutions are large. In order to find the solution for the peak force and to investigate its transition from shallow to deep failure mechanism, finite element analyses of lateral and upward pipe movements are performed for different embedment conditions. Two different soil models (Mohr–Coulomb and Nor–Sand models) are used for the simulations. The accuracy of the analysis is first examined by simulating experimental tank tests. The analysis is further extended to deeper embedment ratios of as large as 100. The obtained finite element results are used to construct a design chart for deep embedded pipelines.     

数值模拟在镁合金焊接接头深冷处理中的应用

利用所建立的有限元模型,对焊接接头进行深冷处理前后的温度场分析,再把模型转化成结构单元进行应力应变场分析。计算结果表明:深冷处理后,受焊接热源影响的焊缝及附近区域横向残余应力和纵向残余应力均增大,距焊缝较远的母材区产生了预压应力;深冷处理后,横向和纵向残余变形均减小。     

赞比亚康科拉竖井项目设计与施工服务的体会

以赞比亚康科拉竖井项目为例,通过对该项目设计与施工服务过程中的实践经验,探讨了中国国际工程公司在国际工程项目中应注意的事项。     

板材深加工产业的探讨

钢材延伸产业链作为钢铁产业链的重要组成部分,其发展快慢与好坏直接影响到我国钢铁业自身发展。通过不同类型钢材深加工现状的分析,国内外钢铁企业发展深加工实践的探讨,我国应采用大力发展钢材深加工产业应对激烈市场竞争的发展策略。     

LF深脱硫技术在安钢的应用

介绍和分析了安阳钢铁集团150t LF钢包精炼炉深脱硫工艺。生产实践表明:合理的渣系组成、渣量、温度控制、吹氩搅拌及喂线技术是实现快速深脱硫的关键环节。     

加钛深冲钢的工艺优化实践

为了获得深冲性能优良的冲压用冷轧板,对济钢加钛深冲钢的化学成分进行了优化设计,即降低了碳质量分数,并采用高温终轧、高温卷取、适宜的冷轧变形量(70%～75%) 等优化的热轧、冷轧和退火工艺。工艺优化后的加钛深冲钢具有比原工艺更低的下屈强比、更高的塑性应变比、更高的应变硬化指数和更多的有利的{111}取向织构比例,最终使其具有优异的深冲性能,满足了市场的深冲压要求。