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1 – 10 of over 2000Ali Hashemi, Parsa Yazdanpanah Qaraei and Mostafa Shabanian-Poodeh
The aim of this paper is to provide a simple yet accurate and efficient geometric method for thermal homogenization of impregnated and non-impregnated coil winding technologies…
Abstract
Purpose
The aim of this paper is to provide a simple yet accurate and efficient geometric method for thermal homogenization of impregnated and non-impregnated coil winding technologies based on the concept of thermal resistance.
Design/methodology/approach
For regular windings, the periodic microscopic cell in the winding space is identified. Also, for irregular windings, the average microscopic cell of the winding is determined. An approximation is used to calculate the thermal resistance of the winding cell. Based on this approximation, the winding insulation is considered as a circular ring around the wire. Mathematical equations are obtained to calculate the equivalent thermal resistance of the cell. The equivalent thermal conductivity of the winding is calculated using equivalent thermal resistance of the cell. Winding thermal homogenization is completed by determining the equivalent thermal properties of the cell.
Findings
The thermal pattern of different windings is simulated and compared with the results of different homogenization methods. The results show that the proposed method is applicable for a wide range of windings in terms of winding scheme, packing factor and winding insulation. Also, the results show that the proposed method is more accurate than other winding homogenization methods in calculating the equivalent thermal conductivity of the winding.
Research limitations/implications
In this paper, the change of electrical resistance of the winding with temperature and thermal contact between the sub-components are ignored. Also, liquid insulators, such as oils, and rectangular wires were not investigated. Research in these topics is considered as future work.
Originality/value
Unlike other homogenization methods, the proposed method can be applied to non-impregnated and irregular windings. Also, compared to other homogenization methods, the proposed method has a simpler formulation that makes it easier to program and implement. All of these indicate the efficiency of the proposed method in the thermal analysis of the winding.
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Tasneem Ahmad and Vinita Krishna
The case is based on the data collected from various secondary sources only.
Abstract
Research methodology
The case is based on the data collected from various secondary sources only.
Case overview/synopsis
Godi India, a lithium-ion cell manufacturing company in India, was working to design e-cell for electric vehicles (EV) which would be compatible with Indian conditions and reduce the cost of battery to the extent possible because e-cell contributes half of the electric vehicle’s price. Godi India was set up in January 2020 by Mahesh Godi. Looking for opportunities in India after having worked in the USA for 17 years, Mahesh found that even with the rise in EV the lithium-ion cell manufacturing in India was almost zero. Using innovation as its main strategy, the start-up started its operation with a team of 30 scientists. The start-up already registered 25 patents under its name with few awaiting. Most of the EV companies relied on Chinese lithium-ion cell. Local lithium-ion cell manufacturing was believed to be the key for EV industry growth in a country. Central government production linked schemes worth INR 18,100 crore were signed by major players like Ola electric, Reliance new energy and Rajesh exports to develop locally manufactured advance cells. The push from the government for locally manufacturing the cells was a major trigger for the rise in the EV industry. The case provides the analysis of the strategies applied by the company to grow in the lithium-ion cell manufacturing industry.
Complexity academic level
This case can be used in strategic management, entrepreneurship and general management courses/modules at the Undergraduate and Postgraduate level.
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The purpose of this paper is twofold: first, a case study on applying lean principles in manufacturing operations to redesign and optimize an electronic device assembly process…
Abstract
Purpose
The purpose of this paper is twofold: first, a case study on applying lean principles in manufacturing operations to redesign and optimize an electronic device assembly process and its impact on performance and second, introducing cardboard prototyping as a Kaizen tool offering a novel approach to testing and simulating improvement scenarios.
Design/methodology/approach
The study employs value stream mapping, root cause analysis, and brainstorming tools to identify root causes of poor performance, followed by deploying a Kaizen event to redesign and optimize an electronic device assembly process. Using physical models, bottlenecks and opportunities for improvement were identified by the Kaizen approach at the workstations and assembly lines, enabling the testing of various scenarios and ideas. Changes in lead times, throughput, work in process inventory and assembly performance were analyzed and documented.
Findings
Pre- and post-improvement measures are provided to demonstrate the impact of the Kaizen event on the performance of the assembly cell. The study reveals that implementing lean tools and techniques reduced costs and increased throughput by reducing assembly cycle times, manufacturing lead time, space utilization, labor overtime and work-in-process inventory requirements.
Originality/value
This paper adds a new dimension to applying the Kaizen methodology in manufacturing processes by introducing cardboard prototyping, which offers a novel way of testing and simulating different scenarios for improvement. The paper describes the process implementation in detail, including the techniques and data utilized to improve the process.
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Elsa Araceli Revollo Sarmiento, Deisy Krzemien, Maria Celeste López Moreno and Leticia Vivas
The purpose of this paper is to describe the perceptions that older people in Argentina have about the use of cell phones and to analyze their influence on user behavior. At the…
Abstract
Purpose
The purpose of this paper is to describe the perceptions that older people in Argentina have about the use of cell phones and to analyze their influence on user behavior. At the same time, it was intended to analyze whether sociodemographic factors influence these perceptions.
Design/methodology/approach
The authors conducted a study with a non-experimental, cross-sectional and cross-correlational design; a non-probabilistic sample of 138 intentionally selected older people was chosen.
Findings
The frequency and years of cell phone use, as well as the applications used, are influenced by the perceptions that older people have about cell phone use. In addition, it was found that age, gender and socio-educational level determine the perceptions that older people have about cell phone use.
Originality/value
This research has implications for interventions aimed at improving older people’s functional health. Understanding the perceptions of older people in relation to technology will enable the enhancement of its utility to foster an autonomous lifestyle and social integration in old age.
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Halla Falih Bakheit, Sebastien Taurin, Elwaleed Mohamed Elamin and Moiz Bakhiet
Monocytes are a leukocytes’ subset that plays an important role in immunity. Protein kinase B (AKT) is involved in monocytes' survival, proliferation and differentiation. Using…
Abstract
Purpose
Monocytes are a leukocytes’ subset that plays an important role in immunity. Protein kinase B (AKT) is involved in monocytes' survival, proliferation and differentiation. Using phorbol 12-myristate 13-acetate (PMA) as an inducer for cell line U937 differentiation into macrophage-like cells may be used as a model for cancer cell therapy or other biomedical research studies. The authors investigated the Akt1 signaling pathway's involvement with PMA as a differentiating agent and survival in the U937 cell line.
Design/methodology/approach
PMA was utilized to stimulate the differentiation of the U937 cell line into macrophage-like cells at a concentration of 10 nM. Akt1-phosphorylated Serine 473, Bad-phosphorylated Serine 136 and Caspase9-phosphorylated Serine 196 were tested by flow cytometry for the involvement of the Akt1 signaling pathway during differentiation in addition to the expression of CD14, CD206 and CD83. DNA cell cycle variation analysis was done using PI staining and cell viability and apoptosis detection using Annexin V and PI flow cytometry.
Findings
There was a decrease in phosphorylated Akt1 and Bad activation and an increase in Caspase9 activation, with an increase in surface markers CD14, CD206 and CD83 acquired by PMA-differentiated cells. DNA cell cycle analysis revealed cell accumulation in the G2/M phase and fewer cells in the S phase of PMA-induced U937. Apoptosis induction for Ly294002 or Wortmannin-inhibited cells and part of PMA-induced cells were detected.
Originality/value
These results may be used to create a model for biomedical research studies and advance the understanding of the mechanism involving differentiation of the U937 cell line.
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Nasser Baharlou-Houreh, Navid Masaeli, Ebrahim Afshari and Kazem Mohammadzadeh
This paper aims to investigate the effect of partially blocking the cathode channel with the stair arrangement of obstacles on the performance of a proton exchange membrane fuel…
Abstract
Purpose
This paper aims to investigate the effect of partially blocking the cathode channel with the stair arrangement of obstacles on the performance of a proton exchange membrane fuel cell.
Design/methodology/approach
A numerical study is conducted by developing a three-dimensional computational fluid dynamics model.
Findings
As the angle of the stair arrangement increases, the performance of the fuel cell is reduced and the pressure drop is decreased. The use of four stair obstacles with an angle of 0.17° leads to higher power density and a lower pressure drop compared to the case with three rectangular obstacles of the same size and maximum height. The use of four stair obstacles with an angle of 0.34° results in higher power density and lower pressure drop compared to the case with two rectangular obstacles of the same size and maximum height.
Originality/value
Using the stair arrangement of obstacles as an innovation of the present work, in addition to improving the fuel cell’s performance, creates a lower pressure drop than the simple arrangement of obstacles.
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Jinbei Tian, Mohammed S. Ismail, Derek Ingham, Kevin J. Hughes, Lin Ma and Mohamed Pourkashanian
This paper aims to investigate the impact of three different flow channel cross sections on the performance of the fuel cell.
Abstract
Purpose
This paper aims to investigate the impact of three different flow channel cross sections on the performance of the fuel cell.
Design/methodology/approach
A comprehensive three-dimensional polymer electrolyte membrane fuel cell model has been developed, and a set of conservation equations has been solved. The flow is assumed to be steady, fully developed, laminar and isothermal. The investigated cross sections are the commonly used square cross section, the increasingly used trapezoidal cross section and a novel hybrid configuration where the cross section is square at the inlet and trapezoidal at the outlet.
Findings
The results show that a slight gain is obtained when using the hybrid configuration and this is because of increased velocity, which improves the supply of the reactant gases to the catalyst layers (CLs) and removes heat and excess water more effectively compared to other configurations. Further, the reduction of the outlet height of the hybrid configuration leads to even better fuel cell performance and this is again because of increased velocity in the flow channel.
Research limitations/implications
The data generated in this study will be highly valuable to engineers interested in studying the effect of fluid cross -sectional shape on fuel cell performance.
Originality/value
This study proposes a novel flow field with a variable cross section. This design can supply a higher amount of reactant gases to the CLs, dissipates heat and remove excess water more effectively.
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Mozhgan Hosseinnezhad and Zahra Ranjbar
The purpose of this paper is to introduce flexible dye-sensitized solar cells (FDSSCs).
Abstract
Purpose
The purpose of this paper is to introduce flexible dye-sensitized solar cells (FDSSCs).
Design/methodology/approach
In the third generation solar cells, glass was used as a substrate, which due to its high weight and fragility, was not possible to produce continuously. However, in flexible solar cells, flexible substrates are used as new technology. The most important thing may choose a suitable substrate to produce a photovoltaic (PV) device with optimal efficiency.
Findings
Conductive plastics or metallic foils are the two main candidates for glass replacement, each with its advantages and disadvantages. As some high-temperature methods are used to prepare solar cells, metal substrates can be used to prepare PV devices without any problems. In contrast to the advantage of high thermal resistance in metals, metal substrates are dark and do not transmit enough light. In other words, metal substrates have a high loss of photon energy. Like all technologies, PV devices with polymer substrates have technical disadvantages.
Practical implications
In this study, the development of FDSSCs offers improved photovoltaic properties.
Social implications
The most important challenge is the poor thermal stability of polymers compared to glass and metal, which requires special methods to prepare polymer solar cells. The second important point is choosing the suitable components and materials for this purpose.
Originality/value
Dependence of efficiency and performance of the device on the angle of sunlight, high-cost preparation devices components, limitations of functional materials such as organic-mineral sensitizers, lack of close connection between practical achievements and theoretical results and complicated fabrication process and high weight.
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K. Thirumalaisamy and A. Subramanyam Reddy
The analysis of fluid flow and thermal transport performance inside the cavity has found numerous applications in various engineering fields, such as nuclear reactors and solar…
Abstract
Purpose
The analysis of fluid flow and thermal transport performance inside the cavity has found numerous applications in various engineering fields, such as nuclear reactors and solar collectors. Nowadays, researchers are concentrating on improving heat transfer by using ternary nanofluids. With this motivation, the present study analyzes the natural convective flow and heat transfer efficiency of ternary nanofluids in different types of porous square cavities.
Design/methodology/approach
The cavity inclination angle is fixed ω = 0 in case (I) and
Findings
The average heat transfer rate is computed for four combinations of ternary nanofluids:
Practical implications
The purpose of this study is to determine whether the ternary nanofluids may be used to achieve the high thermal transmission in nuclear power systems, generators and electronic device applications.
Social implications
The current analysis is useful to improve the thermal features of nuclear reactors, solar collectors, energy storage and hybrid fuel cells.
Originality/value
To the best of the authors’ knowledge, no research has been carried out related to the magneto-hydrodynamic natural convective
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Wanderson Ferreira dos Santos, Ayrton Ribeiro Ferreira and Sergio Persival Baroncini Proença
The present paper aims to explore a computational homogenisation procedure to investigate the full geometric representation of yield surfaces for isotropic porous ductile media…
Abstract
Purpose
The present paper aims to explore a computational homogenisation procedure to investigate the full geometric representation of yield surfaces for isotropic porous ductile media. The effects of cell morphology and imposed boundary conditions are assessed. The sensitivity of the yield surfaces to the Lode angle is also investigated in detail.
Design/methodology/approach
The microscale of the material is modelled by the concept of Representative Volume Element (RVE) or unit cell, which is numerically simulated through three-dimensional finite element analyses. Numerous loading conditions are considered to create complete yield surfaces encompassing high, intermediate and low triaxialities. The influence of cell morphology on the yield surfaces is assessed considering a spherical cell with spherical void and a cubic RVE with spherical void, both under uniform strain boundary condition. The use of spherical cell is interesting as preferential directions in the effective behaviour are avoided. The periodic boundary condition, which favours strain localization, is imposed on the cubic RVE to compare the results. Small strains are assumed and the cell matrix is considered as a perfect elasto-plastic material following the von Mises yield criterion.
Findings
Different morphologies for the cell imply in different yield conditions for the same load situations. The yield surfaces in correspondence to periodic boundary condition show significant differences compared to those obtained by imposing uniform strain boundary condition. The stress Lode angle has a strong influence on the geometry of the yield surfaces considering low and intermediate triaxialities.
Originality/value
The exhaustive computational study of the effects of cell morphologies and imposed boundary conditions fills a gap in the full representation of the flow surfaces. The homogenisation-based strategy allows us to further investigate the influence of the Lode angle on the yield surfaces.
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