Using ahp and topsis to evaluate welding processes for manufacturing plain carbon stainless steel storage tank

Purpose: In the plain carbon stainless steel storage tank manufacturing industry, there are many types of welding processes used. When selecting the most appropriate welding process is usually done intuitively by the manufacturer depending on its own pre-experiences or common applications in similar companies. However, this approach has a shortsighted view since it generally ignores many conflicting criteria effecting the suitable welding process selection. To overcome this problem, this study aims to evaluate important criteria and alternative welding processes by using some of multi-criteria decision-making approaches to come up with better manufacturing decisions. Design/methodology/approach: This study uses a combined methodology of Analytical Hierarchy Process (AHP) and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). Since both of these techniques require experts’ contributions, a group meeting is held with the experts from academia and industry. Findings: The study identified the important criteria for welding selection process in storage tank manufacturing. With the help of experts in the domain, both weights of decision criteria and ranking of alternative welding processes were determined. Research limitations/implications: Since the techniques used in the study depend on expert’s contribution, the expert knowledge on the welding process is critical. When the expert changes the resulting decision may also change. Therefore, the selection of the expert(s) must be done carefully. Practical implications: The findings of the study are valid for the specific case of the storage tank manufacturing. The study helps manufacturers to understand the framework of welding process selection and make them aware of various techniques (e.g., AHP and TOPSIS). The approach may also be welcomed by other welding applications. Originality/value: The main contribution of the study is mostly on the practical side. To the authors’ best knowledge, this paper is one of few studies investigating the selection of welding process for a plain carbon stainless steel storage tank manufacturing. It may help to increase the attention of researchers on multi-criteria decision-making applications in the welding field. © International OCSCO World Press. All rights reserved. 201

Boundary strata of nonnegatively curved Alexandrov spaces and a splitting theorem

Das Hauptresultat ist der folgende metrische Spaltungssatz: Gegeben sei ein kompakter Alexandrovraum M mit nichtnegativer Krümmung, dessen Rand mehrere Randstrata enthält mit leerem gemeinsamen Schnitt. Dann ist M isometrisch zu einem Produkt von Alexandrovräumen S und D mit nichtnegativer Krümmung. Hierbei ist ein Randstratum definiert als eine extremale Teilmenge von M der lokal konstanten Kodimension 1. Sind davon etwa k+1 derart gewählt, dass ihr gemeinsamer Schnitt leer ist, jeder k-fache Schnitt jedoch nichtleer, so ist der Faktor S von oben isometrisch zu jedem dieser k-fachen Schnitte und hat insbesondere die Dimension dim M - k. Sind weitere Randstrata in M vorhanden, induzieren sie Randstrata von S. Iterative Anwendung des Spaltungssatzes ergibt als Korollar, dass ein n-dimensionaler Alexandrovraum mit nichtnegativer Krümmung höchstens 2n Randstrata besitzt und Gleichheit genau für einen Euklidischen Quader gilt

Numerical simulation of drop impingement and bouncing on a heated hydrophobic surface

The heat transfer of a single water droplet impacting on a heated hydrophobic surface is investigated numerically using a phase field method. The numerical results of the axisymmetric computations show good agreement with the dynamic spreading and subsequent bouncing of the drop observed in an experiment from literature. The influence of Weber number on heat transfer is studied by varying the drop impact velocity in the simulations. For large Weber numbers, good agreement with experimental values of the cooling effectiveness is obtained whereas for low Weber numbers no consistent trend can be identified in the simulations

Case Studies and Theories of the Arms Race

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68522/2/10.1177_096701068601700212.pd