Effects of gating design on structural and mechanical properties of high manganese steel by optimizing casting process parameters

Journal of Mechanical Science and Technology - The impacts of gating design and riser system on structure-property relationship of high manganese steel specimens produced by CO2 sand molding...     

Recent trends in steel fibered high-strength concrete

Steel fibered high-strength concrete (SFHSC) became in the recent decades a very popular material in structural engineering. High strength attracts designers and architects as it allows improving the durability as well as the esthetics of a construction. As a result of increased application of SFHSC, many experimental studies are conducted to investigate its properties and to develop new rules for proper design. One of the trends in SFHSC structures is to provide their ductile behavior that is desired for proper structural response to dynamic loadings. An additional goal is to limit development and propagation of macro-cracks in the body of SFHSC elements. SFHSC is tough and demonstrates high residual strengths after appearance of the first crack. Experimental studies were carried out to select effective fiber contents as well as suitable fiber types, to study most efficient combination of fiber and regular steel bar reinforcement. Proper selection of other materials like silica fume, fly ash and super plasticizer has also high importance because of the influence on the fresh and hardened concrete properties. Combination of normal-strength concrete with SFHSC composite two-layer beams leads to effective and low cost solutions that may be used in new structures as well as well as for retrofitting existing ones. Using modern nondestructive testing techniques like acoustic emission and nonlinear ultrasound allows verification of most design parameters and control of SFHSC properties during casting and after hardening. This paper presents recent experimental results, obtained in the field SFHSC and non-destructive testing. It reviews the experimental data and provisions of existing codes and standards. Possible ways for developing modern design techniques for SFHSC structures are emphasized.     

Accountability to Prevent Corruption in Construction Projects

The American Society of Civil Engineers claims that corruption accounts for an estimated $340 billion of worldwide construction costs each year. Corruption (including bribery, embezzlement, kickbacks, and fraud) in construction projects undermines the delivery of infrastructure services. Further, corruption poses significant risks to construction and engineering companies themselves. What progress has been made, therefore, in reducing the risk of corruption to construction projects? It is the purpose of this paper to argue that with improved accountability, attention to ethics and cultural considerations, and reduced corruption, it is possible to construct, operate, and maintain adequate quality and quantity of infrastructure on a more sustainable basis and thereby improve construction practice. This paper will demonstrate how accountability initiatives in construction projects in developed and developing countries can be of benefit internationally to the public and private sectors as well as nongovernment organizations and researchers in their efforts to reduce corruption in infrastructure services.     

Evaluation of the strength of explosion‐welded bimetallic sheets produced under combined loading conditions

In this paper, conditions for vertical weld defectless formation at horizontal electron-beam welding (EBW) are shown and power-complex selection methods to weld thick-walled constructions by electron beam are developed. Dependences to estimate EBW optimal conditions are obtained.     

Dynamics of support perceptions among couples coping with cardiac illness: The effect on recovery outcomes.

Objective: The current prospective study explored how male cardiac patients' perceptions of received support (i.e., active engagement, protective buffering, and overprotection) moderated the associations between female partners' perceptions of provided support and patients' recovery outcomes: psychological well-being, cholesterol levels, and smoking cessation. Methods: Couples (N = 86) completed surveys at the initial hospitalization after patients' Acute Coronary Syndrome (ACS), and 1 and 6 months later. Partners' ways of providing support and patients' concurrent perceptions of these ways were measured using the Ways of Giving Support Questionnaire; patients' depressive and anxiety symptoms were measured using the Brief Symptom Inventory (BSI). Patients' cholesterol levels were assessed during hospitalization and 6 months later, and smoking habits were reported by the patients. Results: Female partners' protective buffering was positively associated with male patients' depressive symptoms at follow-up only when male patients' own perceptions of partners' protective buffering were low. Female partners' active engagement was positively associated with better odds for male patients' cessation of smoking only when patients' own perceptions of partners' active engagement were high. Finally, female partners' overprotection was associated with higher levels of male patients' harmful blood lipids at follow-up, but only when patients' own perceptions of partners' overprotection were high. Conclusions: As hypothesized, the effect of partners' perceptions of support provided on patients' recovery was moderated by patients' own perceptions of the support received. The effect of this interaction was determined by the specific types of support provided or received and by the specific recovery outcome that was measured. The clinical and theoretical implications of the findings are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Evaluation of the corrosion resistance of explosion‐welded bimetals

New equipment and technologies for low-frequency vibrational treatment of components in engineering are examined. The design of new equipment and its technological characteristics are described, the technology of stress relieving after welding, casting, machining, etc. is discussed, and equipment for inspecting the stresses prior to and after treatment is analysed.     

Web Support System for Business Intelligence in Small and Medium Enterprises

Last decade belongs to business intelligence (BI) because it is one of the few concepts that have actually lived to the expectations. Not only the businesses have adopted it but also have reaped the fruits out of it. But the cost of BI solutions is very high and has restricted small and medium enterprises to use BI solutions. The human resource is also limited and resultantly expensive in this field. This research proposes a web support system for business intelligence which provides automated data mapping and loading from user application to BI framework and also validates it. The system also assists users in getting the outputs in terms of reports and dashboards. The implementation of the proposed framework demonstrates convenience of use and effective cost saving as it does not require any technical expertise. The beauty of this web support system is that all the steps are menu driven and any non-technical user can get hold of it easily.     

Study of Cu-doping effects on magnetic properties of Fe-doped ZnO by first principle calculations

Using ab initio calculations on Zn_{0.975? x} Fe_0.025Cu _x O (x = 0, 0.01, 0.02, 0.05), we study the variations of magnetic moments vs Cu concentration. The electronic structure is calculated by using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that the total magnetic moment and magnetic moment of Fe increase on increasing Cu content. From the density of state (DOS) analysis, we show that Cu-induced impurity bands can assure, by two mechanisms, the enhancement of Fe magnetic moment in Zn_{0.975? x} Fe_0.025Cu _x O.     

The inverse design of the wind turbine blade sections by the singularities method

The aerodynamic characteristics of wind turbines are closely related to the geometry of their blades. The innovation and the technological development of wind turbine blades can be centred on two tendencies. The first is to improve the shape of existing blades; the second is to design new shapes of blades. The aspiration in the two cases is to achieve an optimal circulation and hence enhancing some more ambitious aerodynamic characteristics. This paper presents an inverse design procedure, which can be adapted to both thin and thick wind turbine blade sections aiming to optimise the geometry for a prescribed distribution of bound vortices. A method for simulating the initial contour of the blade section is exposed, which simultaneously satisfy the aerodynamic and geometrical constraints under nominal conditions. A detailed definition of the function characterising the bound vortex distribution is presented. The inviscid velocity field and potential function distributions are obtained by the singularities method. In the design method implemented, these distributions and the circulation of bound vortices on the camber line of the blade profile, are used to rectify its camber in an iterative calculation leading to the final and optimal form of the blade section once convergence is attained. The scheme proposed has been used to design the entire blade of the wind turbine for a given span-wise distribution of bound circulation around the blade contour.     

Biexciton emission and crystalline quality of ZnO nano-objects

The design of cost-effective standards for the quality of nano-objects is currently a key issue toward their massive use for optoelectronic applications. The observation by photoluminescence of narrow excitonic and biexcitonic emission lines in semiconductor nanowires is usually accepted as evidence for high structural quality. Here, we perform time-resolved cathodoluminescence experiments on isolated ZnO nanobelts grown by chemical vapor deposition. We observe narrow emission lines at low temperature, together with a clear biexciton line. Still, drastic alterations in both the CL intensity and lifetime are observed locally along the nano-object. We attribute these to non-radiative recombinations at edge dislocations, closing basal plane stacking faults, inhomogeneously distributed along the NB length. This leads us to the conclusion that the observation of narrow excitonic and biexcitonic emission lines is far from sufficient to grade the quality of a nano-object.