The Effect of Microstructure on the Electrical Properties of Gas-Atomized Copper–Iron Metastable Alloys

Sardar Farhat Abbas,Taek-Soo Kim,Bum-Sung Kim 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.4

With the increase in global demand for highly functionalized materials, there is continued interest in exploiting the materialproperties of metals either individually or in the form of alloys. Copper–iron alloy is considered unique with its remarkablecombination of strength and high electrical conductivity. Due to the low cost of iron, this alloy is expected to replace alloyslike Cu–Ag and Cu–Nb. In order to explore the microstructural features, copper–iron alloy with three Different compositions(10, 30, and 50 at.% Fe) were prepared by a gas atomization process. A detailed microstructural characterization was performedusing scanning electron microscopy, X-ray diff raction, and electron backscattered diff raction. Spark plasma sinteringwas used to sinter the powders to evaluate their electrical conductivities. The mechanism of the microstructure formation isalso discussed in detail. As the Fe content increases, the Fe-rich phase changes its shape from spherical to irregular with aconcomitant sharp decrease in the electrical conductivity of the alloy.

Assessment of Rheological and Piezoresistive Properties of Graphene based Cement Composites

Sardar Kashif Ur Rehman,Zainah Ibrahim,Mohammad Jameel,Shazim Ali Memon,Muhammad Faisal Javed,Muhammad Aslam,Kashif Mehmood,Sohaib Nazar 한국콘크리트학회 2018 International Journal of Concrete Structures and M Vol.12 No.6

The concrete production processes including materials mixing, pumping, transportation, injection, pouring, moulding and compaction, are dependent on the rheological properties. Hence, in this research, the rheological properties of fresh cement paste with different content of graphene (0.03, 0.05 and 0.10% by weight of cement) were investigated. The parameters considered were test geometries (concentric cylinders and parallel plates), shear rate range (300–0.6, 200–0.6 and 100–0.6 s<SUP>−1</SUP>), resting time (0, 30 and 60 min) and superplasticizer dosage (0 and 0.1% by weight of cement). Four rheological prediction models such as Modified Bingham, Herschel–Bulkley, Bingham model and Casson model were chosen for the estimation of the yield stress, plastic viscosity and trend of the flow curves. The effectiveness of these rheological models in predicting the flow properties of cement paste was verified by considering the standard error method. Test results showed that the yield stress and the plastic viscosity increased with the increase in graphene content and resting time while the yield stress and the plastic viscosity decreased with the increase in the dosage of superplasticizer. At higher shear rate range, the yield stress increased while the plastic viscosities decreased. The Herschel–Bulkley model with the lowest average standard error and standard deviation value was found to best fit the experimental data, whereas, Casson model was found to be the most unfitted model. Graphene reduces the flow diameter and electrical resistivity up to 9.3 and 67.8% and enhances load carrying capacity and strain up to 16.7 and 70.1% of the composite specimen as compared with plain cement specimen. Moreover, it opened a new dimension for graphene-cement composite as smart sensing building construction material.

Ricci-Yamabe Solitons and Gradient Ricci-Yamabe Solitons on Kenmotsu 3-manifolds

Sardar, Arpan,Sarkar, Avijit Department of Mathematics 2021 Kyungpook mathematical journal Vol.61 No.4

The aim of this paper is to characterize a Kenmotsu 3-manifold whose metric is either a Ricci-Yamabe soliton or gradient Ricci-Yamabe soliton. Finally, we verify the obtained results by an example.

Seed priming with selenium improves the maize performance

Sardar Alam Cheema,Asmat Ulllah,Muhammad Farooq 단국대학교 국제농업협력연구소 2012 단국대학교 국제농업협력연구소 학술대회 Vol.2012 No.1

A field experiment was conducted to study the effect of selenium priming on growth and productivity of maize at Agronomy Research Area, University of Agriculture, Faisalabad. Maize seeds were primed with different concentrations of selenium (0, 5, 25, 50 and 100 JlM) while untreated seeds were taken as control. Results showed that seed priming with all levels of selenium improved the germination parameters, growth and yield of maize. Seed priming with 50 JlM of selenium recorded maximum grain yield (2.35 t ha- 1) while minimum (1.66 t ha-1) grain yield was observed in case of untreated seeds (control). Further research should be carried out to find out mechanisms of growth and yield improvement of maize as a result of seed priming with selenium.

Current Researches and Future Research Directions in Textile Supply Chain Management

Shaheen Sardar,Young Hae Lee 대한산업공학회 2012 대한산업공학회 추계학술대회논문집 Vol.2012 No.11

Textile industry has played a significant role in the growth of the global economy. Textile products are among the basic needs of human beings. Textile supply chain has a very complex structure. Synchronization in the activities of all participants of the textile supply chain is a challenging task. Textile industry has been sadly neglected by the researchers from the supply chain management perspective. Awareness of the existing situation of the textile supply chain is essential from the optimization point of view. The objective of this study is to investigate the current researches and explore the future research directions in textile supply chain management. A systematic literature review was conducted through maximum possible sources. Then, outcomes of relevant literature were categorized into various groups. Finally, potential areas of future research were highlighted on the basis of literature review, evaluation, and our observations at different textile organizations.

Fire of Thirst

Ali Sardar Jafri 한인문화연구원 1988 한인문화논총 Vol.6 No.-

Microstructural Characterization of Gas Atomized Copper-Iron Alloys with Composition and Powder Size

Abbas, Sardar Farhat,Kim, Taek-Soo The Korean Powder Metallurgy Institute 2018 한국분말재료학회지 (KPMI) Vol.25 No.1

Cu-Fe alloys (CFAs) are much anticipated for use in electrical contacts, magnetic recorders, and sensors. The low cost of Fe has inspired the investigation of these alloys as possible replacements for high-cost Cu-Nb and Cu-Ag alloys. Here, alloys of Cu and Fe having compositions of $Cu_{100-x}Fe_x$ (x = 10, 30, and 50 wt.%) are prepared by gas atomization and characterized microstructurally and structurally based on composition and powder size with scanning electron microscopy (SEM) and X-ray diffraction (XRD). Grain sizes and Fe-rich particle sizes are measured and relationships among composition, powder size, and grain size are established. Same-sized powders of different compositions yield different microstructures, as do differently sized powders of equal composition. No atomic-level alloying is observed in the CFAs under the experimental conditions.

Effect of three-dimensional thermal stresses on torsional vibration of cracked nanorods surrounded by an elastic medium

Abdullah, Sardar S.,Hashemi, Shahrokh H.,Hussein, Nazhad A.,Nazemnezhad, Reza Techno-Press 2021 Advances in nano research Vol.11 No.3

The effect of thermal stresses on the torsional vibration of non, single, and double-cracked nanorods surrounded by an elastic medium is investigated. The differential constitutive relation of the nonlocal theory is applied to the motion equation. Three-dimensional linear thermal strains raised from the thermal stresses are derived using nonlinear Green's strains. The surrounding elastic medium acts as infinite torsional springs. The crack is modeled as a rotational spring. Using Hamilton's principle, the motion equation is obtained. Effect of the crack position and severity, number of cracks, high and low temperatures, nonlocal coefficient, elastic medium stiffness, and nanorod length are examined. The temperature effect on the frequencies depends on the values of the crack parameters, crack numbers, elastic medium stiffness, and nanorod length, and it is independent of the nonlocal scale coefficient. The crack leads to a decrease in the frequencies at any temperature. The elastic medium causes an increase in the frequencies at any temperature.The effect of thermal stresses on the torsional vibration of non, single, and double-cracked nanorods surrounded by an elastic medium is investigated. The differential constitutive relation of the nonlocal theory is applied to the motion equation. Three-dimensional linear thermal strains raised from the thermal stresses are derived using nonlinear Green's strains. The surrounding elastic medium acts as infinite torsional springs. The crack is modeled as a rotational spring. Using Hamilton's principle, the motion equation is obtained. Effect of the crack position and severity, number of cracks, high and low temperatures, nonlocal coefficient, elastic medium stiffness, and nanorod length are examined. The temperature effect on the frequencies depends on the values of the crack parameters, crack numbers, elastic medium stiffness, and nanorod length, and it is independent of the nonlocal scale coefficient. The crack leads to a decrease in the frequencies at any temperature. The elastic medium causes an increase in the frequencies at any temperature.

Multi Tribo-Performance Optimization of AA7075–Al2O3 Composites by Grey Based Response Surface Methodology

Santanu Sardar,Debdulal Das 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

Any engineering surface, even a highly polished one, is prone to abrasion which incurs most of the wear related expenses. Two-body abrasion causes severe material and dimensional losses and is affected by a variety of extrinsic and intrinsic variables. Furthermore, tribo-responses like wear resistance (WR), coefficient of friction (COF) and abraded surface roughness(ASR) are three distinct characteristics in nature, and therefore, multi-objective optimization is necessary for design andselection of engineering systems. In the present article, tribo-performances of stir-cast alumina reinforced Al–Zn–Mg–Cumatrix composites in terms of WR, COF and ASR were evaluated under two-body abrasion with varying abrasive size, loadand sliding distance. Irrespective of abrasion conditions, the developed composites exhibited superior WR ability with substantiallylower COF but much greater ASR than alloy. All three tribo-responses were first converted into a single responseof grey relational grade (GRG); afterwards, response surface based central composite design was adopted to improve triboperformancesof the composites through optimal factor setting by which WR would become the greatest, and COF and ASRwould be the lowest. Abrasive size followed by reinforcement quantity was evaluated as the preeminent one among all thefactors on GRG. The role of different control factors on observed tribo-characteristics was explained via identification ofvarious micro-mechanisms of abrasion.

A Preliminary Result of Systematic Literature Review on Human Status Detection using Machine Learning Techniques

Suman Kalyan Sardar(수만 칼얀 사르다르),Naveen Kumar(나빈 쿠마르),Seul Chan Lee(이슬찬) 대한인간공학회 2021 대한인간공학회 학술대회논문집 Vol.2021 No.11

Objective: The purpose of this study is to evaluate the importance of major research areas by identifying different machine learning techniques that influence key research fields on Human Status Detection (HSD). Background: HSD is concerned with the study of human-system interactions that uses theory, concepts, data, and techniques to design in order to improve human well-being and total performance. The basic premise of HSD is that effective performance comes from user-centered design and a comprehensive understanding of the user’s skills, needs, and preferences. Several machine learning algorithms have been used in the literature to measure the cognitive and physical workload status of the users. Method: In this research, PRISMA model has been applied to gather articles from three databases namely, ScienceDirect, IEEE Xplore, and Association for Computing Machinery (ACM). Sixteen keywords has been selected for collecting the articles from the databases. The following criterion is considered to develop protocol: (1) inclusion/exclusion criteria, (2) study selection, (3) data extraction, (4) data synthesis. Results: A total number of 82 articles were identified using an iterative collaboration of 80 keyword combinations addressing issues in different physical workloads and cognitive loads. A list of important occurrences was identified that may have an impact on the publication pattern. Conclusion: Recent publications on human status detection appear to be primarily concerned with cognitive load whereas previous articles were on detecting physical workload. Application: This study helps domain researchers to identify HSD techniques for their experimental studies.