Modified Schapery’s Model for Asphalt Sand

Asphalt sand is described as a viscoelastoplastic materials. To involve elastic, viscoelastic, and viscoplastic strain components, a modified Schapery’s model is proposed through adding a viscoplastic term to the Schapery’s model with elastic and viscoelastic terms, and a strain-hardening model is used to describe viscoplastic behavior. A set of uniaxial compression tests, repeated and simple creep-recovery tests in different stress levels are performed to determine the stress-dependent parameters in the model. Finally, the model is validated by comparison with the results from the uniaxial creep experiments. Better agreement than the Schapery’s model indicates that the modified model is practicable to describe the mechanical behavior of asphalt sand in uniaxial compression.     

Refinement of a Design-Oriented Stress–Strain Model for FRP-Confined Concrete

This paper presents the results of a recent study conducted to refine the design-oriented stress–strain model originally proposed by Lam and Teng for fiber-reinforced polymer (FRP)-confined concrete under axial compression. More accurate expressions for the ultimate axial strain and the compressive strength are proposed for use in this model. These new expressions are based on results from recent tests conducted by the writers’ group under well-defined conditions and on results from a parametric study using an accurate analysis-oriented stress–strain model for FRP-confined concrete. They allow the effects of confinement stiffness and the jacket strain capacity to be separately reflected and accounts for the effect of confinement stiffness explicitly instead of having it reflected only through the confinement ratio. The new expressions can be easily incorporated into Lam and Teng’s model for more accurate predictions. Based on these new expressions, two modified versions of Lam and Teng’s model are presented. The first version involves only the updating of the ultimate axial strain and compressive strength equations. The second version caters to stress–strain curves with a descending branch, which is not covered by the original model.     

Furrow Irrigation Advance Simulation Using a Surface–Subsurface Interaction Model

A model for the simulation of furrow irrigation advance was developed based on the Saint-Venant equations for the one-dimensional surface flow and the two-dimensional Richards equation for porous media flow. Solutions are computed numerically using finite differences for the surface flow and finite elements for the subsurface flow. Computations are internally coupled through an iterative procedure. Infiltration is computed with the Richards equation every five nodes used in the surface flow computations and by linear interpolation at the remaining nodes. In addition, the Richards equation is solved at the boundaries of the surface flow domain and in the vicinity of the wave front. The time step is calculated using the Courant–Friedrich–Lewy condition and a stability criterion that accounts for friction effects. This combined criterion prevents numerical instabilities and convergence problems, especially in cases of high friction coefficient, low discharge rates, and/or high infiltration rates resulting generally in low flow depth and slow irrigation advance. The model was evaluated against an approach involving high resolution correspondence used in both surface and subsurface flow, using different soil types, inflow discharge, and stability criteria.     

Accelerating Development Step of Preponderant Mineral Resources,Push Ganzi’s Mining Economic Leap to a New Stage

本文就“加快优势矿产资源开发步伐 ,推动我州矿业经济再上新台阶”的可行性、可能性、重要性、必须坚持的几个原则、必须处理好的几个关系以及应采取何种新举措等方面进行了探讨。     

2009 China’s Aluminum Fabrication Industrial Development Report

<正>1 Overview of Aluminum Fabrication Industry Despite the impact of 2008’s financial crisis on China’s aluminum fabrication industry, China’s output of aluminum products remained the world’s largest in 2009, against overall steady     

Description of a New Tundish Model for Treating RTD Data and Discussion of the Communication “New Insight into Combined Model and Revised Model for RTD Curves in a Multi-strand Tundish” by Lei

Metallurgical and Materials Transactions B -     

Surface Tension of Liquid Fe-O Alloys: Revisiting Belton’s Two-Step Adsorption Model

The effect of oxygen adsorption on the surface tension of liquid iron was investigated using the constrained drop method. Experiments were carried out at 1823 K and 1873 K (1550 °C and 1600 °C) under a CO₂-H₂ gas mixture. The experimental results were interpreted using the Langmuir ideal adsorption model and Belton’s two-step adsorption model; the latter model showed better agreement with the experimental results. According to the two-step model, the surface tension of liquid Fe-O alloys at 1823 K and 1873 K (1550 °C and 1600 °C) can be respectively expressed as follows: $$ \sigma = 1882 - 260[0.25\ln (1 + 2407a_{\text{O}} ) + 0.75\ln (1 + 72a_{\text{O}} )]\quad \left[ {T = 1823\,{\text{K}}\left( {1550\,^\circ {\text{C}}} \right)} \right], $$ $$ \sigma = 1834 - 267[0.25\ln (1 + 1445a_{\text{O}} ) + 0.75\ln (1 + 46a_{\text{O}} )]\quad \left[ {T = 1873\,{\text{K}}\left( {1600\,^\circ {\text{C}}} \right)} \right]. $$      

Development of Water Quality Indexes to Identify Pollutants in Vietnam’s Surface Water

This study presents the first water quality indexes developed to evaluate surface water in Vietnam. The basic water quality index (WQIB) can be effectively used to evaluate the spatial and temporal variations of surface water quality as well as to identify water pollutants. The overall water quality index (WQIO) can provide additional information, particularly on toxic substances contributing to water pollution. The water quality indexes developed for this paper were applied to the national surface-water quality monitoring data taken from 1999 to 2007. Water pollutants were classified into three subcategories: organic and nutrients, particulates, and bacteria. Surface water in northern and central Vietnam was poor in quality and contained organic matter, nutrients, and bacteria. Water in the southern part was mainly polluted by bacteria. Trend analysis results reveal a deterioration in water quality in those provinces under pressure from rapid population growth, urbanization, and industrialization. Vietnam has established an official policy to ensure comprehensive nationwide water quality monitoring by 2020. The implementation of water quality indexes may provide the guiding data for sustainable water-resources management in Vietnam.     

Transient Friction in Pressurized Pipes. I: Investigation of Zielke’s Model

This paper investigates the well-known model for unsteady friction developed by Zielke in 1968. The model is based on weights of past local bulk accelerations and is analytically correct for laminar flow, but computationally demanding. Different models have been proposed using dynamic properties, typically based on instantaneous accelerations (IAB) that are more rapid in computational schemes. Unfortunately, they are not as accurate as Zielke’s model and fail to model certain types of transients. This paper points out that the water hammer transient is dominated by a periodicity varying along the pipe. Because of this, the unsteady friction calculated by the Zielke model is distributed nonuniformly along the pipe, and changes in the pipe length change the local unsteady friction. This phenomenon may explain why IAB models using calibrated coefficients to match experimental results have a large span in value for the reported coefficients. This paper will hopefully contribute to further work to find highly accurate and rapid models. The subject deserves to be brought up for discussion as a part of a total understanding of the problem.     

Development of China’s Air Conditioner Industry and Forecast on Copper Tube Demand

##正##With the continual shifting of air conditioner manufacturing industry to China's mainland, the focus of industry competition also is becoming     

Current Situation and Development Tendency of China’s Electronic Copper Foil Industry-Part Ⅰ

In 2011, in despite of production expansion slowdown of China’s electronic copper foil industry due to global economic downturn, European debt crisis and global inflation, China’s production capacity of copper foil rose through extensive construction of new and extension projects.     

Development of a Rheological Model of Hot Deformation as Exemplified by 1424 and В-1461 Aluminum Lithium Alloys

Russian Journal of Non-Ferrous Metals - A variant of a rheological model of hot deformation is proposed: the law of hyperbolic sine, which, as opposed to standard law, accounts not only for the...     

Contractual Approach for Facilitating the Resolution of Dispute over a Contractor’s Failure to Comply with Time Limit for Notice of Delays

The enforcement of a contractor’s notice of delays and claims as “a condition precedent” to a contractor’s claims is a controversial issue among practitioners, researchers, and legal scholars. Strict enforcement or liberal interpretations (no enforcement) of time limit for a contractor’s notice have some implications for the success of projects and for the construction industry. This paper examines and compares the different views regarding enforceability of notice provisions. The paper evaluates those views and thereafter proposes an alternative contractual approach for dealing with a contractor’s noncompliance with the provision. The applicability of the proposed approach is evaluated vis-à-vis legal principles. The proposed approach appears to be practical and equitable. It could facilitate early resolution of disputes relating to notice. It could also make the outcome of notice-related dispute more predictable. Considering the contractual, legal, and practical problems that could arise from a strict enforcement and a liberal interpretation (no enforcement) of time limit for a contractor’s notice, the paper highlights the benefits of the proposed approach to the employers (project owners), contractors, and the construction industry at large.     

Numerical Simulation of Innovative Operation of Blast Furnace Based on MultiFluid Model

A multifluid blast furnace model was simply introduced and was used to simulate several innovative ironmaking operations. The simulation results show that injecting hydrogen bearing materials, especially injecting natural gas and plastics, the hydrogen reduction is enhanced, and the furnace performance is improved simultaneously. Total heat input shows obvious decrease due to the decrease of heat consumption in direct reduction, solution loss and silicon transfer reactions. If carbon composite agglomerates are charged into the furnace, the temperature of thermal reserve zone will obviously decrease, and the reduction of ironbearing burden materials will be retarded. However, the efficiency of blast furnace is improved just due to the decrease in heat requirements for solution loss, sinter reduction, and silicon transfer reactions, and less heat loss through top gas and furnace wall. Finally, the model is used to investigate the performance of blast furnace under the condition of top gas recycling together with plastics injection, cold oxygen blasting and carbon composite agglomerate charging. The lower furnace temperature, extremely accelerated reduction rate, drastically decreased CO2 emission and remarkably enhanced heat efficiency were obtained by using the innovative operations, and the blast furnace operation with superhigh efficiency can be realized.     

Premium-Rating Model for Workers’ Compensation Insurance in Construction

Providing adequate workers’ compensation insurance (WCI) is mandatory by legislation in most countries for employers to hire workers. It is enforced to safeguard the interests of occupational injury victims while eliminating their employers’ financial burden of compensation. WCI’s significance in construction is immeasurable because the construction industry appears to be recording higher injury and fatality rates globally. On the other hand, insurance companies must be meticulous in deciding premiums for WCIs for construction projects. Traditionally, insurers have been adopting the experience modification rating technique for premium-rating of WCI. However, this technique has been proven ineffective for construction applications due to the unique characteristics of construction projects. Hence, a new premium-rating model for construction was developed and tested in the Singapore general insurance industry. The proposed model streamlines structured analyses of project hazards, contractors’ safety management systems, market conditions, and insurers’ internal factors to decide optimal premiums. Moreover, it infuses the partnering notion in WCI for construction. The implementation of the proposed model in the insurance industry would facilitate accident control in the construction industry and thereby loss minimization for insurers.