Viswanatha B.M., M. Prasanna Kumar, S. Basavarajappa and T.S. Kiran
This paper aims to investigate the wear behaviors of aged metal matrix composites and of the as-cast Al-Si alloy by using a pin-on-disk wear testing machine at room temperature.
Abstract
Purpose
This paper aims to investigate the wear behaviors of aged metal matrix composites and of the as-cast Al-Si alloy by using a pin-on-disk wear testing machine at room temperature.
Design/methodology/approach
Hypoeutectic (Al-7Si) alloy reinforced with low volume fractions of SiC particles (SiCp) and graphite (Gr) particles were prepared by the stir-casting process. It was found that the addition of 9 Wt.% of SiCp and 3 Wt.% of Gr particles conferred a beneficial effect in reducing the wear rate of the composites.
Findings
The worn-out surfaces of the specimens were examined using scanning electron microscopy (SEM); the extensive micro cracking occurs on the surface of the Al-7Si alloy tested at lower loads. The growth of these microcracks finally led to the delamination of the base alloy surface. The reinforcements (SiCp and Gr) particles tended to reduce the extent of plastic deformation in the surface layer, thereby reducing extensively the occurrence of micro cracking in the composites.
Originality/value
From the results, it is revealed that the quantity of wear rate was less for aged specimens compared to the as-cast specimens. The worn-out surfaces were studied using electron dispersive spectroscopy, and wear debris was analyzed using SEM.
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BM Viswanatha, M Prasanna Kumar, S Basavarajappa and TS Kiran
This paper aims to investigate the microstructure, hardness and tribological properties of hypoeutectic (Al-7Si) matrix reinforced with fixed quantities of 3 Wt.% graphite (Gr…
Abstract
Purpose
This paper aims to investigate the microstructure, hardness and tribological properties of hypoeutectic (Al-7Si) matrix reinforced with fixed quantities of 3 Wt.% graphite (Gr) and x Wt.% SiCp (x = 3, 6 and 9) hybrid composites.
Design/methodology/approach
The composites were fabricated by stir cast technique. The microstructure, hardness and tribological measurements were carried out on the base alloy and composites. The tribological investigation was carried out on pin-on-disc wear testing machine under dry sliding condition.
Findings
The wear rate decreases with the increase of SiCp into A356-3Gr composites. The composite containing A356-9SiCp-3Gr had better hardness and good wear resistance compared to the base alloy. Scanning electron microscope (SEM) and electro dispersive spectrometry (EDS) images were used to study the reinforcement distribution and worn-out surface of the specimens.
Originality/value
The present paper brings out a clear picture of the various events that take place under the worn-out surfaces leading to the generation of mechanical mixed layer.
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Junwei Wu, Xiao Wang, Luhai Zhou, Xicheng Wei and Wurong Wang
Serpentine is usually added into the lubricant oil to form a self-repairing protective layer on worn ferrous surface. But few works have paid close attention to the preparation of…
Abstract
Purpose
Serpentine is usually added into the lubricant oil to form a self-repairing protective layer on worn ferrous surface. But few works have paid close attention to the preparation of composites with the addition of serpentine. In this work, serpentine reinforced Al matrix composites were successfully prepared to be industrial lubrication components. And its fabricating parameters, compressive strength and tribological properties were analyzed.
Design/methodology/approach
An MM-W1 three-pin-on-disk apparatus was used to investigate the tribological properties. The worn surface, microstructure and cross-sectional morphologies were characterized by scanning electron microscopy equipped with energy dispersive spectroscopy. The compression test was carried out on a universal testing machine. An X-ray diffractometer was used to investigate the phase constitutions. The decomposition temperature of serpentine powders was investigated by a thermal analyzer, which allows simultaneous differential scanning calorimetry and thermogravimetry. With the help of finite element method model, a diagrammatic model of the self-repairing surface layer was developed to analyze the anti-friction mechanism.
Findings
Through evaluating density and Brinell hardness, sintering at 560°C for 3 h are the appropriate parameters for fabricating the composites. Compressive strength was increased by the addition of serpentine. A self-repairing surface layer was formed, reducing the friction coefficient. And a diagrammatic model of the self-repairing surface layer was developed to analyze the anti-friction mechanism.
Originality/value
Serpentine was added in fabricating the Al matrix composites for the first time. Sintering parameters were optimized to make better Al/Si/serpentine composites. Compressive strength was increased by the addition of serpentine. A self-repairing surface layer was formed, reducing the friction coefficient under the dry sliding condition. And a diagrammatic model of the self-repairing surface layer was developed to analyze the anti-friction mechanism. It is hoped to be helpful in further confirming the factors for the formation of the self-repairing surface layer, and in designing a new industrial anti-friction composite used for dry sliding conditions.
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Kalyan Sagar Kadali, Moorthy Veeraswamy, Marimuthu Ponnusamy and Viswanatha Rao Jawalkar
The purpose of this paper is to focus on the cost-effective and environmentally sustainable operation of thermal power systems to allocate optimum active power generation…
Abstract
Purpose
The purpose of this paper is to focus on the cost-effective and environmentally sustainable operation of thermal power systems to allocate optimum active power generation resultant for a feasible solution in diverse load patterns using the grey wolf optimization (GWO) algorithm.
Design/methodology/approach
The economic dispatch problem is formulated as a bi-objective optimization subjected to several operational and practical constraints. A normalized price penalty factor approach is used to convert these objectives into a single one. The GWO algorithm is adopted as an optimization tool in which the exploration and exploitation process in search space is carried through encircling, hunting and attacking.
Findings
A linear interpolated price penalty model is developed based on simple analytical geometry equations that perfectly blend two non-commensurable objectives. The desired GWO algorithm reports a new optimum thermal generation schedule for a feasible solution for different operational strategies. These are better than the earlier reports regarding solution quality.
Practical implications
The proposed method seems to be a promising optimization tool for the utilities, thereby modifying their operating strategies to generate electricity at minimum energy cost and pollution levels. Thus, a strategic balance is derived among economic development, energy cost and environmental sustainability.
Originality/value
A single optimization tool is used in both quadratic and non-convex cost characteristics thermal modal. The GWO algorithm has discovered the best, cost-effective and environmentally sustainable generation dispatch.
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Manikandan Subramaniyan, Sasitharan Subramaniyan, Moorthy Veeraswamy and Viswanatha Rao Jawalkar
This paper aims to address not only technical and economic challenges in electrical distribution system but also environmental impact and the depletion of conventional energy…
Abstract
Purpose
This paper aims to address not only technical and economic challenges in electrical distribution system but also environmental impact and the depletion of conventional energy resources due to rapidly growing economic development, results rising energy consumption.
Design/methodology/approach
Generally, the network reconfiguration (NR) problem is designed for minimizing power loss. Particularly, it is devised for maximizing power loss reduction by simultaneous NR and distributed generation (DG) placement. A loss sensitivity factor procedure is incorporated in the problem formulation that has identified sensitivity nodes for DG optimally. An adaptive weighted improved discrete particle swarm optimization (AWIDPSO) is proposed for ascertaining a feasible solution.
Findings
In AWIDPSO, the adaptively varying inertia weight increases the possible solution in the global search space and it has obtained the optimum solution within lesser iteration. Moreover, it has provided a solution for integrating more amount of DG optimally in the existing distribution network (DN).
Practical implications
The AWIDPSO seems to be a promising optimization tool for optimal DG placement in the existing DN, DG placement after NR and simultaneous NR and DG sizing and placement. Thus, a strategic balance is derived among economic development, energy consumption, environmental impact and depletion of conventional energy resources.
Originality/value
In this study, a standard 33-bus distribution system has been analyzed for optimal NR in the presence of DG using the developed framework. The power loss in the DN has reduced considerably by indulging a new and innovative approaches and technologies.
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Robert J. Ceglie, Ginger Black and Somer Saunders
COVID-19’s influence on the teaching profession will be felt for many years as teachers faced experiences that they have never encountered. The pandemic forced already taxed…
Abstract
COVID-19’s influence on the teaching profession will be felt for many years as teachers faced experiences that they have never encountered. The pandemic forced already taxed teachers to assume additional responsibilities, many of which they were not prepared to deal with. The result was an exodus of teachers from the profession, and those who remained reported challenges that impacted their personal and professional lives. The authors describe the effects on teachers and the impact that this had on them, including reasons why many departed from teaching. In closing, the authors offer recommendations to teacher preparation programs, districts, and schools.
TS Kiran, M Prasannakumar, S Basavarajappa and BM Viswanatha
The purpose of the paper is to study the dry sliding wear behavior of as-cast and heat-treated zinc-aluminum (ZA-27) alloy, reinforced with silicon carbide and graphite particles…
Abstract
Purpose
The purpose of the paper is to study the dry sliding wear behavior of as-cast and heat-treated zinc-aluminum (ZA-27) alloy, reinforced with silicon carbide and graphite particles.
Design/methodology/approach
The alloy and composite samples were prepared with stir casting technique. Heat treatment was carried out for samples at a temperature of 370°C followed by quenching in water at room temperature. Subsequently, the heat-treated samples were aged at 180°C and quenched in water at room temperature. The wear tests were carried using pin-on-disc apparatus at room temperature at different applied loads, sliding speed and sliding distance.
Findings
The wear volume loss of as-cast samples was more compared with heat treated samples. Composites exhibited improved wear resistance than base alloy.
Originality/value
Hybrid metal matrix composites with heat treatment has exhibited superior wear behavior in dry sliding conditions.
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Claire Nolasco Braaten and Lily Chi-Fang Tsai
This study aims to analyze corporate mail and wire fraud penalties, using bounded rationality in decision-making and assessing internal and external influences on prosecutorial…
Abstract
Purpose
This study aims to analyze corporate mail and wire fraud penalties, using bounded rationality in decision-making and assessing internal and external influences on prosecutorial choices.
Design/methodology/approach
The study analyzed 467 cases from 1992 to 2019, using data from the Corporate Prosecution Registry of the University of Virginia School of Law and Duke University School of Law. It examined corporations facing mail and wire fraud charges and other fraud crimes. Multiple regression linked predictor variables to the dependent variable, total payment.
Findings
The study found that corporate penalties tend to be lower for financial institutions or corporations in countries with US free trade agreements. Conversely, penalties are higher when the company is a U.S. public company or filed in districts with more pending criminal cases.
Originality/value
This study’s originality lies in applying the bounded rationality model to assess corporate prosecutorial decisions, unveiling external factors’ influence on corporate penalties.