微利时代下的铜精炼企业精细化管理

本文以我国铜精炼行业为例，强调实施精细化管理的意义，提出精细化管理实施所需遵循的原则及铜精炼企业在实施精细管理规程中所面临的问题，最后归纳了实施精细化管理的对策和策略，旨在为我国铜精炼企业实施有效的精细化管理提供参考意见和建议。     

企业实施ERP系统的风险分析与控制探索

企业实施ERP系统的首要任务是解决投资的风险问题，这种风险存在于实施过程的整个周期中，它包括项目规划、项目预准备、实施过程和系统运行。章围绕金川公司信息化建设提出的要求，从实施ERP系统将面临的软件风险、实施风险、转变风险作了较深刻的论述；同时，探索性地阐述了预防这些风险，企业在实施ERP项目时应采取的对策与进行的风险控制措施。     

构筑目标利润导向的全面预算管理体系的实践

文章从企业实践出发，论述了如何运用全面预算管理这一先进管理技术工具，有效组织营运，为企业战略的实施服务。本文结合企业建立和实施全面预算管理体系的实践，剖析了建立和实施全面预算管理体系的重点和难点，阐述了如何建立和实施全面预算管理体系；目标管理；绩效考核。     

提高产品竞争力的必由之路--实施PDM

综合概述了企业实施PDM的必要性、重要性，以及企业如何来实施PDM，企业实施PDM所带来的效益等。     

中小企业与ERP

中国有几百万个有一定规模的中小企业，在企业信息化的过程中，他们大部分都将或早或晚地采用ERP系统来提升在国际市场上的竞争能力，为了能够正确引导中小企业选择与实施ERP系统，对ERP系统在中小企业的实施提供一些经验，希望能够帮助中小企业在实施ERP的过程中少走不必要的弯路，成功实施ERP。     

完善和深化昆钢科研专利管理的思路

针对昆钢科研和专利管理的现状，论述了科研管理中，立题与解题，项目实施与技术总结的关系，专利管理中，增效与保护，授权与实施的关系。提出了建立企业难题库，实行立题与解题分离管理及建立科研基金，提高专利实施率等建议对策。     

浅谈企业成功实施企业资源计划的关键因素

以某公司实施企业资源计划（ERP）过程为例，论述了企业实施ERP应该注意的几个方面，为企业成功实施ERP系统提供借鉴。     

采用现代化管理方法 实施高标准班组建设工程

采用现代化管理方法实施高标准班组建设工程王恩顺，周东晨唐山钢铁（集团）公司从１９８６年开始实施班组建设工程，推动了企业“双文明”建设水平的提高。去年底，唐钢在总结经验的同时，进一步查找差距，提出实施高标准班组建设工程，进一步跟上国际企业管理新潮流，坚...     

实施ISO14000标准是外向型企业的必由之路

本文简介了实施ＩＳＯ１４０００环境管理标准的及其在国内外实施情况，指出在 中国家实施ＩＳＯ１４０００标准的机遇和挑战并存，并结合实际阐述了首钢实施ＩＳＯ１４０００标准的具体做法。     

试论尊重差异的教学策略

在课堂教学中，学生是一个独特的生命存在。尊重学生的独特性和差异性，实现课堂教学的个性化，促进学生良好个性品质和独特特性的形成与发展，是当代课堂教学改革的重要课题。为此，课堂教学应缩小班级规模，实施小班化教学；采用现代化的教学手段，实施多媒体教学；根据学生的个性差异，实施个别化教学。     

New Orleans Levee System Performance during Hurricane Katrina: London Avenue and Orleans Canal South

Hurricane Katrina was one of the worst natural disasters in U.S. history. The effects of the hurricane were particularly devastating in the city of New Orleans. Most of the damage was due to the failure of the levee system that surrounds the city to protect it from flooding. This paper presents the results of centrifuge models conducted at Rensselaer Polytechnic Institute and the U.S. Army Corps of Engineers simulating the behavior of the levees at London Avenue North and South that failed during Hurricane Katrina. Those levees failed without being overtopped by the storm surge. Also included are the results of a centrifuge model of one levee section at Orleans Canal South, which did not fail during the hurricane. The key factor of the failure mechanism of the London Avenue levees was the formation of a gap between the flooded side of the levee and the sheetpile. This gap triggered a reduction of the strength at the foundation of the protected side of the levee. The results are fully consistent with field observations.     

Drawdown due to Temporally Varying Pumping Discharge: Inversely Estimating Aquifer Parameters

A ramp kernel method is proposed for accurately calculating the drawdown due to any temporal variation in pumping discharge. The use of the ramp kernels assumes the linear variation between the two consecutive measured pumping discharges. The prior studies assume a rectangular variation between the two consecutive measured pumping discharges. In the rectangular variation, a uniform pumping rate is assumed during a time span. An analytical equation for calculating the ramp kernel is derived. An optimization method is used with the proposed ramp kernels for inversely estimating the aquifer parameters from drawdown due to an arbitrary unsteady pumping discharge. Unlike the prior methods, the proposed method accurately identifies the parameters even when the sampling interval for the drawdown and pumping discharge is longer than that needed for assuming a linear variation. The proposed method outperforms the prior method. Application of the proposed method is illustrated using examples.     

Stiffness Degradation and Time to Cracking of Cover Concrete in Reinforced Concrete Structures Subject to Corrosion

Corrosion-induced cracks in reinforced concrete (RC) structures degrade the stiffness of the cover concrete. The stiffness degradation is mainly caused by the softening in the stress-strain relation in the cracked concrete. Limited efforts have been made to model the cracking and the corresponding effects on the cover concrete, despite of its importance in assessing and modeling the behavior of RC structures. This paper proposes a stiffness degradation factor to model the stiffness degradation of the cover concrete subject to cracking. The proposed factor is computed in terms of the cracking strain corresponding to the maximum opening of the concrete cracks based on an energy principle applied to a fractured RC structure. The time to cracking of the cover concrete is then determined as the time from the corrosion initiation needed by the crack front to reach the outer surface of the cover concrete. The proposed stiffness degradation factor and the method to compute the time to cracking are illustrated through two numerical examples. The times to cracking of the cover concrete that are predicted using the proposed method are in agreement with the measured values from laboratory experiments.     

Computational Analysis of Masonry Structures with a Funicular Model

This paper presents a computational approach for the assessment of masonry structures based on the well known analogy between the equilibrium of arches and that of hanging strings or cables working in tension. According to the analogy, the hanging strings model the inverted shape of the equilibrium lines (or thrust lines) describing the locus of the equilibrium forces acting across the sections of the arch. The approach proposed combines two developments. First, a new cable element is proposed to numerically model the strings used to describe the equilibrium lines. The formulation proposed, obtained as a modification of the conventional equations for inextensible cables, is based on an exact analytical derivation. Compared to other available numerical approaches, it has the advantage of ensuring the exact equilibrium of the cable net after deformation. Second, complementary algorithms are proposed for the assessment of the strength of masonry structures by the application of the limit theorems of plasticity (static approach). These algorithms are intended to find optimized solutions complying with the so-called safe (or lower-bound) and uniqueness theorems. Two examples of application are described to illustrate the accuracy of the method and its ability to handle masonry structural systems.     

Position‐Force Adaptive Control for Construction Robots

Typical tasks in construction engineering that can be performed by robots include the spraying or cleaning of surfaces. Both applications require that the external force at the end effector of the manipulator be properly controlled. In this paper, the force‐control problem in spraying is analyzed. The paper shows that an unpredictable jet force causes the end effector to diverge from its desired trajectory. The interface between the end effector of the robot and the jet force is modeled as soft contact because both force error and displacement of the end effector are measurable. Therefore, the force‐control problem is simplified to the position‐control problem. The proposed control scheme, using a position‐force adaptive controller, is applied to counterbalancing a jet force. Computer simulation demonstrates that the scheme works well. The maximal position error can be controlled to within 4 mm with the new controller.     

Purging of a Neutrally Buoyant or a Dense Miscible Contaminant from a Rectangular Cavity. I: Case of an Incoming Laminar Boundary Layer

The flow past two-dimensional (2D) channel cavities along with the removal of neutrally buoyant or dense miscible contaminants introduced instantaneously inside the cavity are studied using eddy resolving techniques. In the simulations, the incoming boundary layer is laminar and the flow is observed not to transition to turbulence as it is convected over the cavity. As for these flow conditions the main coherent structures in the separated shear layer over the cavity are quasi-dimensional, 2D simulations are performed. It is found that the mechanism of removal of the contaminant is very different between the neutrally buoyant and buoyant cases. In the neutrally buoyant case the contaminant is purged from the cavity mostly due to the interactions between the vortices shed in the separated shear layer with the main recirculation eddies inside the cavity and with the trailing edge corner. In the simulations in which a dense contaminant is introduced inside the cavity, after the initial stages of the mass exchange process, the main phenomenon is the presence of a large amplitude internal wave motion which interacts with a strong cavity vortex situated near the trailing edge corner in between the shear layer and the density interface. The density variation across this oscillatory interface is strong. Through this interaction wisps of denser contaminant are extracted from the region beneath the density interface, before being ejected from the cavity by the separated shear layer vortices. The values of the global mass exchange coefficients for the different phases of the purging process are estimated from simple dead-zone models. As expected, the purging process is delayed in the case in which the density of the contaminant is larger than the one of the carrying fluid.     

Formation of Secondary Containment Systems Using Permeation of Colloidal Silica

U.S. Environmental Protection Agency (USEPA) regulations require the capture of spills from liquid tanks containing hazardous chemicals by using a secondary containment system. Compacted clay or geomembrane liners are commonly used in secondary containment systems, but they are cumbersome when used in conjunction with existing liquid tanks because of pipeline networks surrounding the tanks. This study evaluates the formation of hydraulic barriers for secondary containment through the permeation of colloidal silica grout. A simplified infiltration model is presented to predict the downward movement of the colloidal silica grout into a soil layer, considering the time-dependent increase in dynamic viscosity of the colloidal silica for different concentrations of an electrolyte accelerator. Because the simplified infiltration model cannot predict the soil-grout interaction or the permeation of the colloidal silica by fingering, its results were calibrated by using the observations from a large-scale column test involving the permeation of colloidal silica into sand. The predicted position of the wetting front was found to match that of the experiment when the parameter governing the change in viscosity of the colloidal silica was increased by a factor of 30. The infiltration model calibrated with observations from column infiltration experiments provides a simple approach to the design of the secondary containment systems using permeation of colloidal silica.     

Horizontal Injection of Gas–Liquid Mixtures in a Water Tank

Experiments were carried out to investigate the behavior of horizontal gas–liquid injection in a water tank. Measurements of bubble properties and mean liquid flow structure were obtained. The turbulence in the liquid phase appears to help generating bubbles with relatively uniform diameters of 1–4?mm. Both bubble properties and mean liquid flow structure depended on the gas volume fraction and the densimetric Froude number at the nozzle exit. It was found that the bubbles strongly affected the trajectory of the water jet, which behaved similarly to single-phase buoyant jets. However, at gas volume fractions smaller than about 0.15, the water jet completely separated from the bubble core. Bubble slip velocity was also found to be higher than the terminal velocity for isolated bubbles reported in the literature. Dimensionless correlations were proposed to describe bubble characteristics and the trajectory of the bubble plumes and water jets as a function of the gas volume fraction and the densimetric Froude number. Finally, applications of the results for aeration/mixing purposes are presented.     

Failure Analysis of a Bridge Embankment with Cracked Approach Slabs and Leaking Sand

This paper describes a successful failure analysis to determine the causes of loss of backfill sand from a mechanically stabilized earth (MSE) wall, and cracks on the concrete approach slabs on top of it. The Texas Department of Transportation was concerned that the cracks on the approach slabs may be related to the excessive loss of backfill from behind the MSE walls, and that the embankment structure may be unsafe due to potential voids under the concrete slab. Several cubic meters of sugar sand had washed out of the wall and deposited adjacent to the paneled walls. A series of destructive and nondestructive tests were carried out to determine the causes of the problems. It was found that the cracking of the approach slab and the loss of backfill were unrelated. Suggestions for resolving both problems were made based on this study.     

Generalized Model for Geosynthetic-Reinforced Granular Fill-Soft Soil with Stone Columns

This paper pertains to the development of a mechanical model to predict the behavior of a geosynthetic-reinforced granular fill over soft soil improved with stone columns. The saturated soft soil has been idealized by Kelvin–Voight model to represent its consolidation behavior. The stone columns are idealized by stiffer springs. Pasternak shear layer and rough elastic membrane represent the granular fill and geosynthetic reinforcement layer, respectively. The nonlinear behavior of the granular fill and the soft soil is considered. Effect of consolidation of the soft soil due to inclusion of the stone columns has also been included in the model. Plane strain conditions are considered for the loading and reinforced foundation soil system. An iterative finite difference scheme is applied for obtaining the solution, and results are presented in nondimensional form. Comparison between the results from the present study and the analytical solution using theory of elasticity shows reasonable agreement. The advantage of using geosynthetic reinforcement is highlighted. Results indicate that inclusion of the geosynthetic layer effectively reduces the settlement. Nonlinearity in the behavior of the soft soil and the granular fill is reduced due to the use of geosynthetic reinforcement layer.