Applying Minimum Quantity Lubrication (MQL) Method on Milling of Martensitic Stainless Steel by Using Nano Mos2 Reinforced Vegetable Cutting Fluid

AbstractMartensitic stainless steel materials have provided some benefits for aerospace, automotive, hydroelectric engines, cutlery, defense, power hand tools, pump parts, valve seats, chisels, bushings, ball bearings, sporting equipment industry, dental and surgical instruments etc. due to their hardness, strength, and wear resistance. Machining operations such as milling, turning, drilling can be applied to give them the final form. But, these kinds of steels are specified as hard-to-machine materials owing to their high strength, low thermal conductivity and work hardening tendency during machining operations. However, martensitic stainless steels can be machined by using cutting fluids which are environmentally hazardous, unhealthy, and costly. In this study, minimum quantity lubrication (MQL) method was applied by using commercial vegetable cutting fluid and 1%wt. of nano MoS2 (Molybdenum Disulphide) particles reinforced vegetable cutting fluid during milling of AISI 420 martensitic stainless steel with uncoated Tungsten Carbide (WC) cutting tool and the sustainable milling operation was performed. The experiments were carried out at constant cutting speed, feed, and depth of cut. Two different amounts of nanofluids – pressure air mist supplied by MQL system were applied as 20ml/h and 40ml/h. In the consequence of milling operations, initial tool wear and surface roughness were investigated. According to the experimental results, the MQL method reduced the tool wear and surface roughness. In addition, minimum tool wear and surface roughness values were obtained in nano MQL milling at 40ml/h MQL flow rate

Investigating the Impact of Blockchain on Project Risk Management Success: A Structural Equation Model

Lately, the construction industry has shown a great deal of openness to utilizing novel and innovative technologies. The industry's complexity necessitates cooperative and efficient process management. Utilizing value-adding technologies is crucial in thar regard. Among them, blockchain has recently gained prominence as an enabling technology for smart contracts, and secure data management for the construction industry. This study employs a structural equation model to quantify the relationship between risk management (RM), a key project management activity, and blockchain technology. To this end, a survey was created and distributed to construction professionals. A structural equation modeling (SEM) analysis was performed on the data collected from 103 respondents. The findings show that construction project RM can be significantly affected by key blockchain features. This study contributes to the body of knowledge by presenting a conceptual framework that captures the essential elements of RM and blockchain. The results also empirically show that RM and blockchain are closely related, confirming blockchain's potential and relevance in RM applications. The paper also discusses the risks associated with adopting blockchain in the construction industry. The results of this study can help construction practitioners and policy-makers to create plans for incorporating blockchain into RM workflows

Darbe-eko yöntemi kullanılarak beton yol kalınlığının belirlenmesi.

In construction industry Gantt charts, network methods and Line of Balance (LOB) methods are generally used for planning and control of projects. Networking techniques such as Critical Path Method (CPM) and Program Evaluation and Review Technique (PERT) require technical knowledge and could be difficult to implement without proper scheduling background. Gantt charts and LOB techniques are usually easier to implement, however, similar to network techniques these techniques lack visualization. A graphical based scheduling and progress control method could improve existing techniques with visualization so that schedule information could be understood easily by the project participants. Geographic Information Systems (GIS) can be helpful for improving the traditional scheduling methods by utilizing spatial information. In this study, a prototype Global Positioning System (GPS) and GIS based LOB method is proposed. To illustrate the benefits, the proposed method will be applied to a pipeline project.M.S. - Master of Scienc

Kaynak kısıtlı birden fazla projenin çizelgelenmesi problemi için üst-sezgisel yöntemler.

The general resource constrained multi-project scheduling problem (RCMPSP) consists of simultaneous scheduling of two or more projects with common resource constraints, while minimizing duration of the projects. Critical Path Method and other scheduling methods do not consider resource conflicts and practically used commercial project management software packages and heuristic methods provide very limited solutions for the solution of the RCMPSP. Considering the practical importance of multi-project scheduling and the fact that resource constraints impact the schedules and costs significantly, achieving an adequate solution to the problem is crucial for the construction sector. In this research, we present a new hybrid algorithm which is based on genetic algorithm, simulated annealing, backward forward improvement heuristics. The performance of the algorithms is compared with the performances of the known heuristic procedures and commonly used software packages using test instances particularly developed for multi-project environment. Effectiveness of the developed algorithm is further improved with the application of parallel computing strategies with a Graphical Processing Unit (GPU). Results revealed that effective resource management is a vital process but it is ignored by practitioners, heuristic methods and current software packages. Proposed algorithm showed significant improvements on the state of the art algorithms. It is also shown that parallel computing strategies with a GPU has high potential for meta-heuristic applications specifically for construction management research area in which there is a significant gap in the GPU research.Ph.D. - Doctoral Progra

Interlingual term adventure of multinational corporations

Bu çalışma öncelikli olarak terimi tanımlamayı, nelere terim denildiğini, terimlerin hangi durumlarda ve alanlarda kullanıldığını ve kapsadığı özellikleri açıklamayı amaçlamaktadır. Dil unsuru çokuluslu şirketlerde faaliyetlerinin küreselliği sebebiyle her açıdan sorun oluşumuna açık ve hassastır. Dil unsurunu oluşturdukları dil politikaları yöntemleri ile nasıl aştıkları araştırılarak sorun daraltılmış ve dil politikaları dahilinde terim oluşturma yöntemleri, kullanımları ve ölçünlemeleri incelenmiştir. Çokuluslu şirketlerin bahsi geçen küresel faaliyetlerinin dünya dillerine ve terim birimlerine olan etkileri iki araştırma konusu ile ortaya konulması planlanmıştır. Çokuluslu şirketlerin hizmet ve üretim faaliyetleri ile dünya ticareti ve üretiminde çok büyük bir yere sahip olması nedeniyle ürün ve hizmetlerini dünya pazarına arz ederken bu pazar dillerini nasıl etkiledikleri merak konusudur. Bu çerçevede dört çokuluslu şirkete ait yaygın kullanımı olan dört benzer ürün seçilmiş ve kullanım kılavuzları incelenmiştir. Bu inceleme ile dört çokuluslu şirketin dil politikaları hakkında bilgiler verilmiş ve Türkçe, İngilizce, Fransızca dillerinde terimler saptanarak hem çeviribilimsel hem de terimbilimsel açıdan karşılaştırılmaları amaçlanmıştır. Diğer yandan bu kuruluşlar dünya genelinde devasa sayıda istihdam sağlamaktadır. Dolayısıyla oluşturdukları dil politikaları birçok insanı kapsar. Bu bağlamda sayıları neredeyse bir milyarı bulan bu çalışanların dillerini nasıl etkilediklerini araştırmak gereklidir. Bu sebeple birbirinden farklı alanlarda faaliyet gösteren dört çokuluslu şirketten, farklı görevlerde bulunan dört çalışan ile mülakat yapılarak bağlı oldukları kurumların dil politikaları hakkında sorular yöneltilmiştir. Alınan cevaplar doğrultusunda çokuluslu şirketlerin faaliyet alanında kullandıkları Türkçe, İngilizce ve İspanyolca terimler incelenmiştir. Ortaya çıkan bulgular ışığında çokuluslu şirketlerin dil politikalarında terime ve terimler vasıtasıyla dünya dillerine etkileri üzerine bir sonuç oluşturmak istenmiştir.This research primarily aims to define the term, to clarify what are called terms, in which situations and areas they are used, and what characteristic they possess. Language factor in multinational companies is open and sensible to occurrence of problem in every aspect due to their global activities. The problem is narrowed down by researching how they overcame the language factor with the language policy methods they constitute and within language policies, methods of term formation are examined. The effects of the mentioned global activities of multinational companies on world languages and term units are planned to be revealed with two research topics. Since multinational companies have a great place in world trade and production with their service and production activities, it is a matter of wonder that how they affect these market languages while supplying their products and services to the world market. In this framework, widely used four similar products of four multinational corporations are selected and their user manuals are analyzed. The language policies of four multinational companies were sampled and the terms in Turkish, English and French are determined by this analysis and these terms are aimed to compare both in terms of translation studies and terminology. On the other hand, these organizations employ a huge number of jobs around the world. Therefore, their constituted language policies comprise many people. In this regard, it is necessary to search first that how language policies affect the languages of these employees, whose number is almost a billion. For this reason, four employees in different positions, from four multinational companies operating in different fields, are interviewed and questions are asked about the language policies of their affiliated institutions. In line with the received answers, Turkish, English and Spanish terms that used in their activities of multinational corporations are examined. In the light of the findings, it is aimed to create a result on the effects of the language policies of the multinational corporations on the world languages through ter

Backward-Forward Hybrid Genetic Algorithm for Resource-Constrained Multiproject Scheduling Problem

Despite the fact that companies manage multiple projects simultaneously, most research on resource-constrained project scheduling has focused on single projects. This paper presents a backward-forward hybrid genetic algorithm (BFHGA) for optimal scheduling of a resource-constrained multiproject scheduling problem (RCMPSP). The new approach combines complementary strengths of the backward-forward scheduling method, genetic algorithms, and simulated annealing. BFHGA was tested on four single-project case examples, one portfolio case example, one real portfolio, and 26 test portfolio instances. The proposed algorithm obtained the best solution for all of the single-project case examples, and outperformed five state-of-the-art meta-heuristics and five popular heuristics for the resource-constrained multiproject scheduling problems. The computational results show that the BFHGA is a fast and effective algorithm for scheduling multiple projects with common limited resources. The performance gap between the BFHGA and popular heuristics reveals the potential for improving the existing heuristics for the RCMPSP. (C) 2014 American Society of Civil Engineers

Geographic information system-based visualization system for planning and monitoring of repetitive construction projects

This study presents a visualization system based on a geographic information system (GIS) for planning and monitoring the progress of construction projects that are repetitive due to their geometrical layout. A prototype system was developed and applied to an actual pipeline project to demonstrate the advantages of the proposed approach. The primary advantage of the system is improved visualization of geographical conditions and their impact on the progress rate. Enhanced visual representation of the schedule and work sequence can be achieved by time-lapse simulation. The system also provides a framework for effective communication of schedule, progress, and geographic information among the project participants. Future enhancements to the prototype system are addressed

Systematic evaluation of the aggregate types and properties on metakaolin based geopolymer composites

Although aggregates constitute the largest volume in geopolymer composites, there are limited studies related to this parameter. This study investigates the effect of different types of aggregates on the mechanical and durability properties of metakaolin (MK) based geopolymer composites. For this study, while using metakaolin as the main raw material, slag (S) was used to gain an early setting. Six different sand types (silica sand, river sand, sandstone, Rilem sand, waste concrete aggregate, and basalt sand) were used in the geopolymer mortar. The ultrasonic pulse velocity (UPV) and flexural and compressive strength results of 7, 28, and 56 days were found to examine the effect of aggregates, while the unit weight, voids ratio, water absorption, and workability properties of the samples were also investigated. XRD analyzes were performed for the crystalline materials' structure. After 56 days, the samples were exposed to 180 cycles of the freezing-thawing test (1 cycle consists of 12 h at -18 degrees C and 12 h at +4 degrees C) and high temperatures of 200, 400, 600, and 800 degrees C. After the tests, UPV and strength results were found and weight changes were also examined. Also, an abrasion test was applied. SEM analyzes were carried out pre and post the high-temperature test. Test results have shown that basalt sand added samples produced better results due to their more dense and compact structure compared to other aggregates. Similarly, high results were obtained by using silica sand and sandstone. In the case of using waste concrete aggregate, it was seen that acceptable results were obtained in terms of structural features. (C) 2021 Elsevier Ltd. All rights reserved

Critical Sequence Crashing Heuristic for Resource-Constrained Discrete Time-Cost Trade-Off Problem

Despite the importance of project deadlines and resource constraints in construction scheduling, very little success has been achieved in solving the resource-constrained discrete time-cost trade-off problem (RCDTCTP), especially for large-scale projects. In this paper a new heuristic method is designed and developed to achieve fast and high-quality solutions for the large-scale RCDTCTP. The proposed method is based on the novel principles to enable effective exploration of the search space through adequate selection of the activities to be crashed for a resource constrained schedule, by only crashing the activities with zero float in a resource constrained-schedule, which form the critical sequence. The computational experiment results reveal that the new critical sequence crashing heuristic outperforms the state-of-the-art methods, both in terms of the solution quality concerning project cost and computation time. Solutions with a deviation of 0.25% from the best known solutions are achieved within seconds for the first time, for a large-scale project including up to 2,000 activities. The main contribution of the new heuristic to practitioners and researchers is that it provides a fast and effective method for optimal scheduling of real-life-size construction projects with project deadlines and resource constraints. (C) 2015 American Society of Civil Engineers