111 research outputs found
Iran’s Foreign policy in Afghanistan: The Current Situation and Future Prospects
The overthrow of Taliban in Afghanistan in 2001 by the United States eliminated one of the most important threats Iran faced since the revolution of 1979. This article seeks to survey Iran’s policy in post-Taliban Afghanistan in order to evaluate the feasibility of cooperation between Iran and the Western countries, particularly the United States. Our main question is that: what does Iran want in Afghanistan and what are the prospects of Iran’s cooperation with the Western countries there? To answer this question, we first survey briefly Iran’s policy in Afghanistan from 1979 to 2001. Then Iran’s policy since the removal of Taliban from power will be discussed in the second section. In the third section, we will speculate on the possibility of future cooperation between Iran and the Western countries. Our main argument is that since Iran mainly seeks a regional solution for the current chaos in Afghanistan including its own role in state/nation-building there, the prospect for cooperation with the Western countries is not very bright. 
Localised web bearing behaviour of cold-formed austenitic stainless-steel channels : review of design rules and new insight under interior loading
Stainless steels are modern high-performance construction materials exhibiting excellent corrosion resistance, recyclability, ductility, and durability which make them appealing to use in the construction industry. However, when used as structural sections, they are subjected to localised failure in the web. This study aims to examine the structural behaviour of cold-formed low-carbon content standard austenitic 304L and 316L stainless steel channels under localised interior bearing loads. The results of 21 tests on unlipped channels with different cross-section sizes and thicknesses are presented. A nonlinear quasi-static Finite Element (FE) model is then developed. The FE model is validated against experimental test results and demonstrated good agreement in terms of bearing strength and failure modes. In addition, the experimental and FE results are used to compare the results against the results predicted in accordance with the American specification SEI/ASCE 8:2002 and European Standard EN 1993-1-4:2006. It is found that the current design equations are unreliable and too unconservative to use for cold-formed austenitic stainless steel unlipped channels, especially when compared to SEI/ASCE 8:2002, as much as 41%
Web Bearing Capacity of Cold-Formed Ferritic Stainless Steel Unlipped Channels with Web perforations under the End-Two-Flange (ETF) Loading
Laboratory and numerical evaluations on the web bearing capacity of unlipped cold-formed ferritic stainless steel channels are described in this paper. The channels considered have circular perforations in the web and are loaded under the end-two-flange (ETF) load case. A total of 387 results comprising 27 laboratory and 360 numerical results are presented. A nonlinear quasi-static finite element (FE) model was developed for the numerical investigation. An extensive parametric study is described to determine web bearing capacity reduction factors for different sizes of circular web perforations and cross-section dimensions; the circular web perforations are either centred or offset to the load and reaction plates. It is noted that no cold-formed stainless steel standard provides capacity reduction factors for any end-two-flange load case. The capacity reduction factor equations are first compared to reduction factors previously recommended for lipped cold-formed stainless steel channels. It is found that these existing equations are unreliable and unconservative for unlipped channels by as much as 11%. From both laboratory and finite element results, web bearing capacity design equations are proposed for both sections, with and without web perforations
Web Crippling Behavior of Cold-Formed Ferritic Stainless Steel Unlipped Channels under Interior-One-Flange And End-One-Flange Loadings
The web crippling strength of cold-formed ferritic stainless steel unlipped channels subject to interior-one-flange and end-one-flange loading is considered in this paper. A total of 144 results are presented, comprising 36 laboratory and 108 numerical results. These results cover the cases of both flanges restrained and unrestrained to the load and reaction plates. Unlike other work in the literature, the numerical analysis in this paper uses nonlinear quasi-static finite element analysis with an implicit integration scheme, which has advantages over static and quasi-static with an explicit integration scheme analyses, particularly for post buckling predictions of unlipped channels subject to web crippling. The laboratory and numerical investigations show current stainless steel design guidance to be too conservative. In terms of design standards, while no cold-formed stainless steel standard distinguishes between flanges restrained and unrestrained to the load and reaction plates, with each standard providing only one equation to cover both restrained and unrestrained, the web crippling strengths for the flanges unrestrained case were found to be higher than those predicted from SEI/ASCE-8 by as much as 24%. Also, the web crippling strengths for the flanges restrained case are shown to be higher than those predicted from equations found in the literature by as much as 48%. New web crippling design equations are proposed; the proposed equations are shown to be reliable when compared against laboratory and numerical results
Environmental and social performance disclosure and shareholders’ wealth- a perspective from Malaysian companies
Since sustainability reporting is a mean to communicate with a wide range of internal and external stakeholders and also reflect the companies’ sustainability performance, which inspires sustainable growth and development, consequently increasingly more and more stakeholders including shareholders ask for sustainability disclosures. In some Countries CSR reporting has become mandatory by legislation and companies have to disclose their environmental and social activities. Sustainability reporting has become mandatory for Malaysian public listed companies (PLC) since 2007. There a declarative about CSR activities in all Malaysian companies but number of sustainability indicators and the quality of disclosure are different among different companies. Since the main goal of each business is to maximize its shareholders’ wealth, and CSR practices would occur costs for companies, this paper amis to find any significant relationship between level of CSR disclosure and companies share price and net profit. The result. The paper studied through 45 Malaysian public listed companies in three years (From 2008-2010). The results indicated that companies with higher level of sustainability disclosure have higher share price and have higher net profi
Voluntary sustainability disclosure, revenue, and shareholders wealth- a perspective from Singaporean companies
There is an unprecedented growth among wide range of stakeholder’s attention to environmental and social performance, and disclosure by companies. People within a community are worried about natural resources, air and water pollution, as well as low income-tier group of the community. Companies started to perform in a way to minimize their negative and adverse impact on natural scarce resources, and practice some social-friendly activities in order to either build a shared value for long term purpose, and to gain customers and shareholders attention for short term purposes. Since environmental and social issues are associated with peoples’ right and public law, thus some governments have legislated certain rules and regulations and also have made CSR disclosure as a mandatory practice for public listed firms. But CSR disclosure is still optional in most of countries. Environmental and social performance and disclosure in Singapore are not mandatory. So Singaporean public listed companies perform and disclose their CSR activities voluntarily.. Findings of this research show that there is a positive and significant relationship between environmental and social performance disclosure as well as revenue. This research investigated the relationship between environmental and social disclosure and shareholders wealth in Singapore; meanwhile it has found that there is a positive and considerable relationship between sustainability reporting and amount of paid dividend and share price as well
Experimental and Analytical Studies of Cold-Formed Steel Sections with Edge-Stiffened Circular Holes Subjected to Web Crippling
Cold-formed steel sections are often used as wall studs or floor joists and such sections often include web holes for ease of installation of services. The holes are normally punched or bored and are unstiffened; when the holes are near to points of concentrated load, web crippling can be the critical design consideration. Recently, a new generation of cold-formed steel channel sections with edge-stiffened circular holes has been developed. The web holes are stiffened through a continuous edge stiffener/lip around the perimeter of the hole. In this paper, a combination of experimental investigations and non-linear finite element analyses are used to investigate the effect of such edge-stiffened holes under the interior-one-flange (IOF) and end-one-flange (EOF) loading conditions; for comparison, sections without holes and with unstiffened holes are also be considered. A non-linear finite element models are described, and the results compared against the laboratory test results; a good agreement was obtained in terms of both strength and failure modes
Parametric Studies and Design Recommendations of Cold-Formed Steel Sections with Edge-Stiffened Circular Holes Subjected to Web Crippling
A parametric study of cold-formed steel sections with edge-stiffened circular holes subjected to web crippling under one-flange loading condition was undertaken using finite element analysis. The effect of different hole sizes, edge-stiffener length and distances of the web holes to the near edge of the bearing plate on the web crippling strengths of channel sections were investigated. The web crippling strengths are influenced by various geometry parameters: the ratio of the hole depth to the flat portion of the web, a/h, the location of the hole as defined by the distance of the hole from the edge of the bearing divided by the flat portion of the web, x/h and the ratio of the edge-stiffener length to the flat portion of the web, q/h. In order to find the effect of a/h, x/h and q/h ratios on web crippling strength of channel sections with web holes, three separate parametric studies were carried out. The results indicate that with a suitable edge-stiffener length, the web crippling strength of cold-formed steel channel section with holes can be as high as the one without holes. In this paper, based on the finite element results a correlation are established for the web crippling strength of the channel sections without web holes, with unstiffened and edge-stiffened circular web holes corresponding with the ratios a/h, x/h and q/h for the interior-one-flange (IOF) and end-one-flange (EOF) loading conditions, respectively
Design of cold-formed stainless steel lipped channel sections with web openings subjected to web crippling under end-one-flange loading condition
This article presents a numerical investigation on the web crippling strength of cold-formed stainless steel lipped channel sections with circular web openings under end-one-flange loading condition. In order to take into account the influence of the circular web openings, a parametric study involving 1992 finite element analyses was performed, covering duplex EN1.4462, austenitic EN1.4404 and ferritic EN1.4003 stainless steel grades; from the results of the parametric study, strength reduction factor equations are proposed. The web crippling strengths predicted by the reduction factor equations are first compared to the strengths calculated using the equations recently proposed for cold-formed carbon steel lipped channel sections. It is demonstrated that the strength reduction factor equations proposed for cold-formed carbon steel are unconservative for the stainless steel grades by up to 7%. Unified strength reduction factor equations are then proposed that can be applied to all three stainless steel grades
Multi-image-feature-based hierarchical concrete crack identification framework using optimized SVM multi-classifiers and D-S fusion algorithm for bridge structures
Cracks in concrete can cause the degradation of stiffness, bearing capacity and durability of civil infrastructure. Hence, crack diagnosis is of great importance in concrete research. On the basis of multiple image features, this work presents a novel approach for crack identification of concrete structures. Firstly, the non-local means method is adopted to process the original image, which can effectively diminish the noise influence. Then, to extract the effective features sensitive to the crack, different filters are employed for crack edge detection, which are subsequently tackled by integral projection and principal component analysis (PCA) for optimal feature selection. Moreover, support vector machine (SVM) is used to design the classifiers for initial diagnosis of concrete surface based on extracted features. To raise the classification accuracy, enhanced salp swarm algorithm (ESSA) is applied to the SVM for meta-parameter optimization. The Dempster–Shafer (D–S) fusion algorithm is utilized to fuse the diagnostic results corresponding to different filters for decision making. Finally, to demonstrate the effectiveness of the proposed framework, a total of 1200 images are collected from a real concrete bridge including intact (without crack), longitudinal crack, transverse crack and oblique crack cases. The results validate the performance of proposed method with promising results of diagnosis accuracy as high as 96.25%
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