Niche comparisons: toward a new approach for analysing competition and organizational performance in the international construction market

Over the past few decades, studies on competition and organizational performance in the international construction market have been prolific. Construction companies are founded, then grow, compete, evolve, and die in the international landscape, a common process from an ecological perspective. However, few studies have considered the international construction market from this perspective. Using niche theory, which was initially populated in the field of natural bio-ecology and then introduced to business management and economics, a NW/O-L (niche width/overlap and location) framework is established in this study. With this framework, the niche evolution of the top 225 international contractors is explored along two dimensions—product and geography. The effects of a proper niche on an international construction company’s performance are also investigated using the cluster analysis method. It was discovered that, despite fluctuations over time, the contractor’s niche is highly related to its performance in the international construction market. The most appropriate niche for international construction contractors is a wide niche width, with a small niche overlap and with its location near to the market centre with comparatively more market resources. However, only a few contractors can survive in this niche, as the majority of contractors are in a narrow niche width, with a comparatively large niche overlap and far from the market centre. Contractors which do not fit either of these two niches have proved to be poor performers in this study.     

A discrete optimization process for the design of horizontal girders of rising sector gate using PIAnO

Many small dams have recently been constructed on several major rivers in the Republic of Korea to utilize these water resources and control water flows. One such water body is the Gangjeong reservoir in the Nakdong River; a rising sector gate was mounted on this reservoir. The finite element analysis (FEA) confirmed the empirical design of the gate to be safe with minor modifications. However, the positions of the horizontal girders are critical in the design of a gate, and it is must be determined by a trial-and-error process. To find the optimal solution for the positions and thicknesses of horizontal girders in a rising sector gate, this paper proposed a new procedure using the commercial optimization package, PIAnO, as well as Pro-Engineer, Hypermesh, and Abaqus. The optimal positions of the horizontal girders are selected from 9 predefined positions. A special technique was developed and applied to change the discrete position set, such as (1, 4, 8) to a continuous dimensionless variable. For this, a FORTRAN program was written to convert the dimensionless variable to a set of position numbers, and vice versa.     

轮载作用下沥青路面三维非线性有限元分析

在解析法基础上的多层弹性体系理论 ,是当前国内外广泛使用的描述沥青路面结构的力学模型 ,它有一些局限性 ,而用解析的方法难以建立起更一般的沥青路面结构的力学模型。以三维非线性有限元模型NAAPS为工具 ,对轮载作用下沥青路面的非线性响应进行了初步分析 ,得到了一些有意义的结论 ,说明了非线性分析在路面结构分析中的广泛前景     

苏皖沿江地区城市空间结构的定量分析

本文选用了19个经济、社会指标、对苏皖沿江地区的区内差异作了聚类分析。其聚类结果对确定南京等市的功能定位有重要的参考价值。在此基础上运用公式计算了区内所有城市的住置中心性，可作为评价各市投资环境的一种重要的判断依据。     

CISPR 20:2005介绍

介绍了CISPR 20:2005新增及变化的内容.对新增加的测试项目如电快速脉冲群、静电放电等进行了说明,增加了图像质量客观评价的方法、频率范围、性能判据变化等内容,并对屏蔽效果新的测试方法进行了介绍.     

Efficient synthesis of enwrapped CuO@rGO nanowire arrays to improve supercapacitor electrode performance

Journal of Applied Electrochemistry - There has been a growing interest in the performance of supercapacitors (SCs) based on Transition Metal Oxides (TMOs). It has recently been included in...     

Ion acceleration at dipolarization fronts associated with the interchange instability in Earth’s magnetotail

Science China Technological Sciences - It has been confirmed that dipolarization fronts (DFs) are the result of the interchange instability in the Earth’s magnetotail. In this paper, we use a...     

Rapid Bonding of Ti3SiC2 and Ti3AlC2 by Pulsed Electrical Current Heating

Inspired by pressure resistance welding of metallic materials, herein we describe how two MAX phases—Ti₃SiC₂ and Ti₃AlC₂—were successfully joined by a rapid electric current heating method in a pulsed electric current sintering furnace. No welding agent was employed and the total processing time was less than 6 min. When the bulk temperature of the joint couple exceeded 1070°C, good joints, with shear strength above 50 MPa, were achieved in both homo‐ and heterojunction joints.     

Densification and mechanical properties of boron carbide with micro-hole array by micro-powder injection molding

For the purpose of obtaining fully dense B₄C with micro hole array of high quality and precision, synthesis of B₄C powders were carried out by micro powder injection molding. Five kinds of additive systems were used and their influences on mechanical properties were investigated. The relative density, Vickers hardness, bending strength, and fracture toughness of the B₄C ceramics with BS10AY additive sintered at 2000 °C for 2 h could reach 97.56%, 3580.4 HV, 355.3 MPa and 5.87 MPa m^1/2, respectively. The temperature was generally 100–200 °C lower than reported temperatures which was attributed to the additives. The improvement in mechanical properties was attributed to grain refinement. A mixture of intragranular and transgranular fractures occurred due to the fine microstructures and the additive systems in the B₄C ceramics after sintering. Micro-hole array with the diameter of 450 μm and the length-diameter ratio of more than 8 were obtained. The inhomogeneous filling of feedstock from the substrate to the thin wall between two adjacent micro holes caused the inhomogeneous shrinkage of the substrate and micro holes.