Lotfısadıgh, Bahram

Profile URL
https://hdl.handle.net/20.500.14411/7762
Name Variants
Lotfisadigh, B. Lotfısadıgh, Bahram Bahram, Lotfısadıgh Lotfisadigh, Bahram L.,Bahram B.,Lotfisadigh L., Bahram Bahram, Lotfisadigh B., Lotfisadigh B.,Lotfısadıgh Lotfısadıgh,B. Lotfisadigh,B. Sadigh, Bahram Lotfi
Job Title
Doktor Öğretim Üyesi
Email Address
bahram.lotfisadigh@atilim.edu.tr
Main Affiliation
Manufacturing Engineering
Status
Former Staff
Website
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
No research topics data found.

Sustainable Development Goals

NO POVERTY1
NO POVERTY
0
Research Products
ZERO HUNGER2
ZERO HUNGER
0
Research Products
GOOD HEALTH AND WELL-BEING3
GOOD HEALTH AND WELL-BEING
1
Research Products
QUALITY EDUCATION4
QUALITY EDUCATION
0
Research Products
GENDER EQUALITY5
GENDER EQUALITY
0
Research Products
CLEAN WATER AND SANITATION6
CLEAN WATER AND SANITATION
0
Research Products
AFFORDABLE AND CLEAN ENERGY7
AFFORDABLE AND CLEAN ENERGY
0
Research Products
DECENT WORK AND ECONOMIC GROWTH8
DECENT WORK AND ECONOMIC GROWTH
0
Research Products
INDUSTRY, INNOVATION AND INFRASTRUCTURE9
INDUSTRY, INNOVATION AND INFRASTRUCTURE
6
Research Products
REDUCED INEQUALITIES10
REDUCED INEQUALITIES
0
Research Products
SUSTAINABLE CITIES AND COMMUNITIES11
SUSTAINABLE CITIES AND COMMUNITIES
1
Research Products
RESPONSIBLE CONSUMPTION AND PRODUCTION12
RESPONSIBLE CONSUMPTION AND PRODUCTION
1
Research Products
CLIMATE ACTION13
CLIMATE ACTION
0
Research Products
LIFE BELOW WATER14
LIFE BELOW WATER
0
Research Products
LIFE ON LAND15
LIFE ON LAND
1
Research Products
PEACE, JUSTICE AND STRONG INSTITUTIONS16
PEACE, JUSTICE AND STRONG INSTITUTIONS
0
Research Products
PARTNERSHIPS FOR THE GOALS17
PARTNERSHIPS FOR THE GOALS
0
Research Products
This researcher does not have a Scopus ID.
This researcher does not have a WoS ID.
No records found in other affiliations.
Scholarly Output

22

Articles

12

Views / Downloads

71/131

Supervised MSc Theses

5

Supervised PhD Theses

1

WoS Citation Count

246

Scopus Citation Count

297

Patents

0

Projects

0

WoS Citations per Publication

11.18

Scopus Citations per Publication

13.50

Open Access Source

5

Supervised Theses

6

JournalCount
Machining Science and Technology3
International Journal of Computer Integrated Manufacturing2
Procedia CIRP2
The International Journal of Advanced Manufacturing Technology2
Artificial Intelligence for Engineering Design, Analysis and Manufacturing: AIEDAM1
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Scholarly Output Search Results

Now showing 1 - 10 of 22
  • Doctoral Thesis
    Havacılık Endüstrisinde Kullanılan Kesilmesi Zor Malzemeler Üzerinde Nanoakışkan Minimum Miktar Yağlama ile Çok Eksenli Ultrasonik Titreşi̇m Destekli Frezelemenin Etkileri Üzerine Bir İnceleme
    (2023) Namlu, Ramazan Hakkı; Lotfi, Bahram; Kılıç, Sadık Engin
    Havacılık sektörü, modern dünyanın önde gelen endüstrilerinden biri olarak öne çıkmaktadır. Bu sektörde Ti-6Al-4V malzemesinin yaygın olarak kullanılması, mükemmel mukavemet-ağırlık oranına ve iyi korozyon direnci gibi özelliklerine sahip olmasından kaynaklanmaktadır. İşleme, malzemeyi nihai şekline dönüştürmek için havacılık sektöründe vazgeçilmez bir süreçtir. Bununla birlikte, Ti-6Al-4V'nin işlenebilirliği, Geleneksel İşleme (Gİ) kapsamında, düşük termal iletkenliği, kesici takımlara yapışma eğilimi ve talaş kaldırmayla ilgili zorluklarla karakterize edilmekte ve bundan dolayı genellikle 'işlenmesi zor' bir malzeme olarak adlandırılmaktadır. İşleme verimliliğini artırmak için, Ultrasonik Titreşim Destekli İşleme (UTDİ) umut vaat eden bir teknik olarak ortaya çıkmıştır. UTDİ, yüksek frekansta, düşük genlikli titreşimleri çeşitli kesme yönlüklerine entegre ederek verimliliği artırmayı amaçlayan hibrit bir işleme yaklaşımıdır. Hibrid işleme stratejileri ile beraber, Ti-6Al-4V'nin işleme performansını artırmak için başka bir yol da soğutma sistemlerini içermektedir. Bu sistemler, malzemenin düşük termal iletkenliğinden kaynaklanan kesme bölgesindeki ısı birikimini azaltmayı amaçlar. Ancak, Geleneksel Kesme Sıvıları'nın (GKS) kullanımı, sınırlı performans artışları ve çevresel ve mesleki sağlık riskleri nedeniyle alternatif tekniklerle değiştirilmektedir. Bu alternatifler arasında, Minimum Miktar Yağlama (MMY), kesme bölgesine yüksek basınçlı hava ile birlikte minimum miktarda yağın aerosol formunda verilmesini içeren bir yöntem olarak ortaya çıkmıştır. Aerosol form, GKS'ye kıyasla kesici takım ile iş parçası arasına daha iyi penetre ederek verimliliğin artmasına katkıda bulunur. Ayrıca, MMY'nin avantajları, Nanoakışkan-MMY (NMMY) olarak bilinen nanoparçacıkların eklenmesi ile daha da artırılmaktadır. NMMY, MMY'de kullanılan yağa nanoparçacıkların entegre edilmesini içerir ve bunların termo-fiziksel özelliklerini kullanarak saf MMY'ye kıyasla üstün işleme verimliliği elde etmeyi amaçlar. Özellikle, en büyük gelişmeler, çeşitli nanoparçacık türlerini birleştiren Hibrid-NMMY (HNMMY) uygulamasıyla elde edilebilir. Bu tez, optimum konsantrasyonları ve uygulama metodolojilerini belirlemek amacıyla, değişik nanoparçacık konsantrasyonları ve bunlara karşılık gelen etkilerle karakterize edilen çeşitli nanoakışkanların kapsamlı bir incelemesini amaçlar. Daha sonra, tez, çok eksenli UTDİ ve NMMY yaklaşımlarının birleşik etkilerini araştırır. Mevcut literatüre göre, daha önce hiçbir araştırma, Ti-6Al-4V üzerinde kanal frezeleme operasyonlarında çok eksenli UTDİ ve NMMY/HNMMY uygulamalarını incelememiştir. Araştırma bulguları, çok eksenli UTDİ ve NMMY'nin birleşik kullanımının Ti-6Al-4V'nin işleme performansında önemli gelişmelere yol açtığını göstermektedir, bu da daha etkili ve sürdürülebilir bir uygulama sağlamaktadır.
  • Article
    Citation - WoS: 15
    Citation - Scopus: 21
    A Survey of Partner Selection Methodologies for Virtual Enterprises and Development of a Goal Programming-Based Approach
    (Springer London Ltd, 2015-11-12) Nikghadam, Shahrzad; Sadigh, Bahram Lotfi; Ozbayoglu, Ahmet Murat; Unver, Hakki Ozgur; Kilic, Sadik Engin
    A virtual enterprise (VE) is a platform that enables dynamic collaboration among manufacturers and service providers with complementary capabilities in order to enhance their market competitiveness. The performance of a VE as a system depends highly on the performance of its partner enterprises. Hence, choosing an appropriate methodology for evaluating and selecting partners is a crucial step toward creating a successful VE. In this paper, we begin by presenting an extensive review of articles that address the VE partner selection problem. To fill a significant research gap, we develop a new goal programming (GP)-based approach that can be applied in extreme bidding conditions such as tight delivery timelines for large demand volumes. In this technique, fuzzy analytic hierarchy process (F-AHP) is used to determine customer preferences for four main criteria: proposed unit price, on-time delivery reliability, enterprises' past performance, and service quality. These weights are then incorporated into the GP model to evaluate bidders based on customers' preferences and goals. We present a case study in which we implement the F-AHP-GP technique and verify the model's applicability, as it provides a more flexible platform for matching customers' preferences.
  • Master Thesis
    İç Ortamda Ortalama Radyan Sıcaklığını Elde Etmek için Farklı Yöntemlerin Doğruluğunun Karşılaştırılması
    (2021) Özbey, Mehmet Furkan; Turhan, Cihan; Lotfısadıgh, Bahram
    Amerikan Isıtma Soğutma ve Klima Mühendisleri Birliği (ASHRAE), ısıl konforu bir kişinin bulunduğu ortamdaki memnuniyetini ifade eden öznel ve zihinsel değerlendirme ile elde edilen zihin koşulları olarak tanımlanmıştır. Isıl konfor, geleneksel olarak Fanger'in Ortalama Tahmini Oy (PMV) / Memnuniyetsizliklerin Tahmini Yüzdesi (PPD) metodu ve kişilerin davranışlarını da içeren adaptif ısıl konfor metotları ile elde edilmektedir. Isıl konfor parametreleri kişisel parametreler (giysi değeri ve metabolizma hızı) ve çevresel parametreler (hava sıcaklığı, bağıl nem, hava hızı ve ortalama radyan sıcaklığı) olarak üzere iki farklı kategoride ele almaktadır. Bu parametreler arasında, Ortalama Radyan Sıcaklık ölçülmesinin ve hesaplanmasının karmaşık olmasından dolayı elde edilmesi zor bir faktördür. İç ortamlarda ortalama radyan sıcaklığı elde etme yaklaşımları hesaplama yöntemleri, ölçüm yöntemleri ve varsayımlar gibi farklı yöntemlere dayanmaktadır. Ancak hesaplama yöntemlerinin karmaşık olması ve ölçüm yöntemleri için kullanılacak ölçüm aletlerinin pahalı ve elde edilmesi zor araçlar olması araştırmacıları doğruluğu kesin olmayan varsayımlara yönlendirmektedir. Bu nedenle, bu çalışmanın amacı ortalama radyan sıcaklığın elde edilme yöntemlerinin ölçüm yöntemlerinden birisi olan ve bu çalışma için üretilen küre termometresini referans alıp diğer metotlar ile karşılaştırılarak tüm yöntemlerin doğruluğunu bulmaktır. Bu çalışmada Köppen- Geiger sınıflandırmasına göre Csb tipi iklim bölgesinde bulunan bir test odası seçilmiştir ve ortalama radyatif sıcaklığı elde etmek için kullanılan 2 farklı hesaplama yöntemi ve 8 farklı varsayım yerinde ölçümle referans metodu ile karşılaştırılmıştır. Sonuçlar, ortalama radyan sıcaklığı elde etmek için varsayımların veya hesaplama yöntemlerinin kullanılmasının, referans yönteme kıyasla %9,1'e varan bir hataya neden olduğunu ortaya koydu.
  • Article
    Citation - WoS: 8
    Citation - Scopus: 10
    Combined Use of Ultrasonic-Assisted Drilling and Minimum Quantity Lubrication for Drilling of Niti Shape Memory Alloy
    (Taylor & Francis inc, 2023-06-24) Namlu, Ramazan Hakki; Lotfi, Bahram; Kilic, S. Engin; Yilmaz, Okan Deniz; Akar, Samet
    The drilling of shape-memory alloys based on nickel-titanium (Nitinol) is challenging due to their unique properties, such as high strength, high hardness and strong work hardening, which results in excessive tool wear and damage to the material. In this study, an attempt has been made to characterize the drillability of Nitinol by investigating the process/cooling interaction. Four different combinations of process/cooling have been studied as conventional drilling with flood cooling (CD-Wet) and with minimum quantity lubrication (CD-MQL), ultrasonic-assisted drilling with flood cooling (UAD-Wet) and with MQL (UAD-MQL). The drill bit wear, drilling forces, chip morphology and drilled hole quality are used as the performance measures. The results show that UAD conditions result in lower feed forces than CD conditions, with a 31.2% reduction in wet and a 15.3% reduction in MQL on average. The lowest feed forces are observed in UAD-Wet conditions due to better coolant penetration in the cutting zone. The UAD-Wet yielded the lowest tool wear, while CD-MQL exhibited the most severe. UAD demonstrated a & SIM;50% lower tool wear in the wet condition than CD and a 38.7% in the MQL condition. UAD is shown to outperform the CD process in terms of drilled-hole accuracy.
  • Article
    Citation - WoS: 17
    Citation - Scopus: 20
    An Experimental Study on Ultrasonic-Assisted Drilling of Inconel 718 Under Different Cooling/Lubrication Conditions
    (Springer London Ltd, 2023-12-01) Erturun, Omer Faruk; Tekaut, Hasan; Cicek, Adem; Ucak, Necati; Namlu, Ramazan Hakki; Lotfi, Bahram; Kilic, S. Engin
    Ultrasonic-assisted drilling (UAD) is one of the efficient and innovative methods to improve the drillability of difficult-to-cut materials. In the present study, the UAD of Inconel 718 was investigated under different cooling and/or lubrication conditions. The drilling tests were carried out at a constant cutting speed (15 m/min) and a feed (0.045 mm/rev) using uncoated and TiAlN-coated solid carbide drills under dry, conventional cutting fluid (CCF), and minimum quantity lubrication (MQL) conditions. The applicability of UAD to drilling Inconel 718 was evaluated in terms of thrust force, surface roughness, roundness error, burr formation, subsurface microstructure and microhardness, tool wear, and chip morphology. The test results showed that, when compared to conventional drilling (CD), UAD reduced the thrust force and improved the hole quality, tool life, and surface integrity under all conditions. Good surface finish, lower roundness error, and minimum burr heights were achieved under CCF conditions. MQL drilling provided lower thrust forces, better tool performance, and good subsurface quality characteristics. In addition, the simultaneous application of CCF-UAD and MQD-UAD showed significantly better performance, especially when using the coated tool.
  • Article
    Citation - WoS: 15
    Citation - Scopus: 16
    Integration of Psychological Parameters Into a Thermal Sensation Prediction Model for Intelligent Control of the Hvac Systems
    (Elsevier Science Sa, 2023-10) Turhan, Cihan; Ozbey, Mehmet Furkan; Lotfi, Bahram; Akkurt, Gulden Gokcen; Gökçen Akkurt, Gülden
    Conventional thermal comfort models take physiological parameters into account on thermal comfort models. On the other hand, psychological behaviors are also proven as a vital parameter which affects the thermal sensation. In the literature, limited studies which combine both physiological and psychological parameters on the thermal sensation models are exist. To this aim, this study develops a novel Thermal Sensation Prediction Model (TSPM) in order to control the HVAC system by considering both parameters. A data-driven TSPM, which includes Fuzzy Logic (FL) model, is developed and coded using Phyton language by the authors. Two physiological parameters (Mean Radiant Temperature and External Temperature) and one psychological parameter (Emotional Intensity Score (EIS) including Vigour, Depression, Tension with total of 32 subscales) are selected as inputs of the model. Besides the physiological parameters which are decided intentionally considering a manual ventilated building property, the most influencing three sub- psychological parameters on thermal sensation are also selected in the study. While the physiological parameters are measured via environmental data loggers, the psychological parameters are collected simultaneously by the Profile of Mood States questionnaire. A total of 1159 students are participated to the questionnaire at a university study hall between 15th of August 2021 and 15th of September 2022. The results showed that the novel model predicted Thermal Sensation Vote (TSV) with an accuracy of 0.92 of R2. The output of this study may help to develop an integrated Heating Ventilating and Air Conditioning (HVAC) system with Artificial Intelligence - enabled Emulators that also includes psychological parameters.
  • Conference Object
    Citation - Scopus: 1
    Ontology Based Virtual Enterprise System Domain Modeling
    (DEStech Publications Inc., 2014) Lotfi Sadigh,B.; Ünver,H.Ö.; Dogdu,E.; Kiliç,S.E.
    A virtual enterprise (VE) is a product oriented temporary consortium which forms a collaboration platform to fulfil a specific common purpose (typically to create a product) by benefiting from various capabilities of multiple VE partner enterprises. VE lifecycle consists of 3 distinct phases including VE Formation, Operation and Dissolution. VE partner enterprises are selected from virtual breeding environment (VBE) based on specific criteria considering the new VE project specifications. In order to select the most appropriate partners for the forthcoming VE project, it is required to have comprehensive information regarding the VBE members, their current conditions, capabilities, capacities and their past performances. This database continuously changes and it is dynamic. Ontologies and the corresponding knowledge bases provide the best tools for modelling such complex domain knowledge and highly dynamic data requirements. Ontologies not only help model and capture complex domain knowledge, but also improve the sharing and reusability of data and knowledge providing a suitable environment for software agents and human communications. The VE system must be able to demonstrate what types of resources exist, where they are located, and how much resource capacity is available to be used by the consortium. In this paper a pilot Virtual Enterprise system model developed for OSTIM organized industrial park in Ankara will be presented in detail. The objective of this system model is to enable SMEs in the region to collaborate effectively in order to produce eco-friendly high value added products. © Copyright 2014 by DEStech Publications, Inc. All rights reserved.
  • Article
    Citation - WoS: 43
    Citation - Scopus: 45
    Enhancing Machining Efficiency of Ti-6al Through Multi-Axial Ultrasonic Vibration-Assisted Machining and Hybrid Nanofluid Minimum Quantity Lubrication
    (Elsevier Sci Ltd, 2024-06) Namlu, Ramazan Hakki; Lotfi, Bahram; Kilic, S. Engin
    Ti-6Al-4V offers a balance of good strength with lightweight properties. Yet, Ti-6Al-4V poses machining challenges, including low thermal conductivity, chemical adhesion to cutting tools, and chip removal difficulties. To improve machining efficiency, Ultrasonic Vibration-Assisted Machining (UVAM) has emerged as a promising approach. UVAM has demonstrated reduced tool wear, cutting forces, and improved surface quality compared to Conventional Machining (CM). Additionally, Minimum Quantity Lubrication (MQL) methods offer sustainable coolant alternatives, with recent research focusing on Nanofluid-MQL (NMQL) and Hybrid Nanofluid-MQL (HNMQL) for enhanced performance. Although there exists a body of literature showcasing the promising effects of UVAM and MQL methods individually, comprehensive investigations into the synergistic effects of these methodologies remain limited. This study addresses these critical research gaps by conducting a systematic examination of combined application of multi-axial UVAM and HNMQL. Specifically, it delves into the comparison of different vibration directions within UVAM, evaluates the effectiveness of UVAM when combined with cutting fluids incorporating Al2O3 and CuO nanoparticles in NMQLs and HNMQLs, and contrasts these novel approaches with conventional machining methods. The study unfolds in three distinct stages. The first stage examines the ultrasonic cutting mechanism and its combined application with the MQL technique. In the second stage, the study investigates the physical properties of the cutting fluids, including contact angle and surface tension. The final stage encompasses slot milling operations, where an array of parameters such as cutting forces, surface roughness, surface topography, surface texture, and the occurrence of burr formations are rigorously analyzed. The results demonstrate that the combination of multi-axial UVAM with HNMQL yields substantial advantages over traditional machining methods. Notably, it leads to a remarkable reduction in cutting forces (up to 37.6 %) and surface roughness (up to 37.4 %). Additionally, this combination engenders the production of highly homogeneous and uniform surface textures, characterized by minimal surface defects and a significantly diminished occurrence of burr formations. These findings underscore the potential of multi-axial UVAM combined with HNMQL as a promising approach in enhancing the machining of Ti-6Al-4V, thus offering a pathway to enhance the efficiency and precision of aerospace component manufacturing processes.
  • Conference Object
    Citation - WoS: 20
    Citation - Scopus: 26
    An Experimental Study on Surface Quality of Al6061-T6 in Ultrasonic Vibration-Assisted Milling with Minimum Quantity Lubrication
    (Elsevier Science BV, 2022) Namlu, Ramazan Hakki; Yilmaz, Okan Deniz; Lotfisadigh, Bahram; Kilic, S. Engin
    Al6061-T6 is frequently used in the automotive and aerospace industries, where milling is an essential process, due to its high strength-to-weight ratio. In order to achieve improved surface quality in milling, Ultrasonic Vibration-Assisted Milling (UVAM) has been introduced recently. Besides, Minimum Quantity Lubrication (MQL) is another advanced method to enhance the surface properties of the cutting by improving the coolant performance. However, the effects of simultaneous implementation of UVAM and MQL methods has not yet been studied sufficiently. This paper investigates the effects of applying UVAM in tandem with MQL in cutting of Al6061-T6. The results showed that surface quality enhanced with this combination. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)
  • Article
    Citation - WoS: 13
    Citation - Scopus: 14
    Predictive Models for Mechanical Properties of Expanded Polystyrene (eps) Geofoam Using Regression Analysis and Artificial Neural Networks
    (Springer London Ltd, 2022-03-13) Akis, E.; Guven, G.; Lotfisadigh, B.
    Initial elastic modulus and compressive strength are the two most important engineering properties for modeling and design of EPS geofoams, which are extensively used in civil engineering applications such as light-fill material embankments, retaining structures, and slope stabilization. Estimating these properties based on geometric and physical parameters is of great importance. In this study, the compressive strength and modulus of elasticity values are obtained by performing 356 unconfined compression tests on EPS geofoam samples with different shapes (cubic or disc), dimensions, loading rates, and density values. Using these test results, the mechanical properties of the specimens are predicted by linear regression and artificial neural network (ANN) methods. Both methods predicted the initial modulus of elasticity (E-i), 1% strain (sigma(1)), 5% strain (sigma(5)), and 10% strain (sigma(10)) strength values on a satisfactory level with a coefficient of correlation (R-2) values of greater than 0.901. The only exception was in prediction of sigma(1) and E-i in disc-shaped samples by linear regression method where the R-2 value was around 0.558. The results obtained from linear regression and ANN approaches show that ANN slightly outperform linear regression prediction for E-i and sigma(1) properties. The outcomes of the two methods are also compared with results of relevant studies, and it is observed that the calculated values are consistent with the results from the literature.