Istanbul Technical University

About: Istanbul Technical University is a education organization based out in Istanbul, Turkey. It is known for research contribution in the topics: Fuzzy logic & Large Hadron Collider. The organization has 12889 authors who have published 25081 publications receiving 518242 citations. The organization is also known as: İstanbul Teknik Üniversitesi & Technical University of Istanbul.

A fuzzy multi-criteria decision approach for software development strategy selection

Abstract: This study proposes a methodology to improve the quality of decision-making in the software development project under uncertain conditions. To deal with the uncertainty and vagueness from subjective perception and experience of humans in the decision process, a methodology based on the extent fuzzy analytic hierarchy process modeling to assess the adequate economic (tangible) and quality (intangible) balance is applied. Two key factors of economic and quality are evaluated separately by fuzzy approaches and both factors' estimates are combined to obtain the preference degree associated with each software development project strategy alternative for selecting the most appropriate one. Using the proposed approach, the ambiguities involved in the assessment data can be effectively represented and processed to assure a more convincing and effective decision-making. Finally, a real case-study is given to demonstrate the potential of the methodology.

Capital budgeting techniques using discounted fuzzy versus probabilistic cash flows

Abstract: Risk analysis involves the development of the probability distribution for the measure of effectiveness. The risk associated with an investment alternative is generally either given as the possibility of an unfavorable value of the measure of effectiveness or measured by the variance of the measure of effectiveness. In an uncertain economic decision environment, an expert's knowledge about discounting cash flows consists of a lot of vagueness instead of randomness. Cash amounts and interest rates are usually estimated by using educated guesses based on expected values or other statistical techniques to obtain them. Fuzzy numbers can capture the difficulties in estimating these parameters. In this paper, the formulas for the analyses of fuzzy present value, fuzzy equivalent uniform annual value, fuzzy future value, fuzzy benefit-cost ratio, and fuzzy payback period are developed and given some numeric examples. Then the examined cash flows are expanded to geometric and trigonometric cash flows and using these cash flows fuzzy present value, fuzzy future value, and fuzzy annual value formulas are developed for both discrete compounding and continuous compounding.

Self-Healing Poly(acrylic acid) Hydrogels with Shape Memory Behavior of High Mechanical Strength

Abstract: A promising strategy to design synthetic hydrogels with the ability to self-heal is to substitute the covalently cross-linked polymer chains by supramolecular ones. Although supramolecular hydrogels generally exhibit rapid self-healing without the need for any stimulus, they suffer from low mechanical strength which prevents them from any stress-bearing applications. Here, we describe a novel way for the production of self-healing hydrogels with shape memory behavior of high tensile strength (0.7–1.7 MPa) and stretch at break (800–900%). Hydrophobically modified poly(acrylic acid) (PAAc) chains with cetyltrimethylammonium (CTA) counterions form the physical network of such hydrogels. They were prepared via micellar copolymerization of acrylic acid with 2 mol % stearyl methacrylate (C18) as the hydrophobic comonomer in an aqueous NaBr solution of cetyltrimethylammonium bromide (CTAB). Extraction of free CTAB micelles from the physical gels results in a drastic increase in their Young’s moduli (from 8–30 to...

Influence of Type of Initiation on Thiol–Ene “Click” Chemistry

Abstract: Thermally and photochemically initiated thiol-ene click reactions using thiol- and allyl- end functionalized linear polystyrenes with various enes (allyl bromide, methyl acrylate, and methyl methacrylate) and thiol (3-mercaptopropionic acid) have been investigated. Allyl- and thiol-end-capped polystyrenes with controlled molecular weight and low polydispersity were prepared by atom transfer radical polymerization (ATRP) of styrene using functional initiator and end group modification approaches, respectively. Thiol-ene reactions can be initiated by both cleavage type photoinitiators such as (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TMDPO) and 2,2-dimethoxy-2-phenyl acetophenone (DMPA) and H-abstraction type photoinitiators such as benzophenone (BP), thioxanthone (TX), camphorquinone (CO), and classical thermal initiator, 2,2'-azobis(isobutyronitrile) (AIBN) at 80 °C. The kinetics of the reactions was monitored online with a real time ATR-FTIR monitoring system and the conversions were determined by 1 H NMR spectroscopy. A comparison of click efficiencies of the studied initiator systems was performed. Compare to the thermal initiators and H-abstraction type photoinitiators, cleavage type photoinitiators were found to induce thiol-ene click reactions with higher efficiency.