Search results

Natural selection is the mechanism of evolution originally proposed by Charles Darwin. This process is driven by mutation and death. Therefore, “individual death” is a critical event for evolution of species. Analogous to the significance of individual death in species evolution, recent biological observations have revealed that “cell death” is an important event for maintenance of individuals and offspring. Cell death is caused not only by injuries and pathological conditions, but also by programed intracellular signals. This type of programed cell death is called “apoptosis.” Apoptosis signals are regulated in mitochondria, eukaryotic organelles of symbiotic origin, and play a critical role in survival of individuals by eliminating some cells.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Recently, powerful instruments for biomedical engineering research studies, including disease modeling, drug designing and nano-drug delivering, have been extremely investigated by researchers. Particularly, investigation in various microfluidics techniques and novel biomedical approaches for microfluidic-based substrate have progressed in recent years, and therefore, various cell culture platforms have been manufactured for these types of approaches. These microinstruments, known as tissue chip platforms, mimic in vivo living tissue and exhibit more physiologically similar vitro models of human tissues. Using lab-on-a-chip technologies in vitro cell culturing quickly caused in optimized systems of tissues compared to static culture. These chipsets prepare cell culture media to mimic physiological reactions and behaviors.

The authors used the application of lab chip instruments as a versatile tool for point of health-care (PHC) applications, and the authors applied a current progress in various platforms toward biochip DNA sensors as an alternative to the general bio electrochemical sensors. Basically, optical sensing is related to the intercalation between glass surfaces containing biomolecules with fluorescence and, subsequently, its reflected light that arises from the characteristics of the chemical agents. Recently, various techniques using optical fiber have progressed significantly, and researchers apply highlighted remarks and future perspectives of these kinds of platforms for PHC applications.

The authors assembled several microfluidic chips through cell culture and immune-fluorescent, as well as using microscopy measurement and image analysis for RNA sequencing. By this work, several chip assemblies were fabricated, and the application of the fluidic routing mechanism enables us to provide chip-to-chip communication with a variety of tissue-on-a-chip. By lab-on-a-chip techniques, the authors exhibited that coating the cell membrane via poly-dopamine and collagen was the best cell membrane coating due to the monolayer growth and differentiation of the cell types during the differentiation period. The authors found the artificial membrane, through coating with Collagen-A, has improved the growth of mouse podocytes cells-5 compared with the fibronectin-coated membrane.

The authors could distinguish the differences across the patient cohort when they used a collagen-coated microfluidic chip. For instance, von Willebrand factor, a blood glycoprotein that promotes hemostasis, can be identified and measured through these type-coated microfluidic chips.

The case is based on the data collected from various secondary sources only.

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.

This case can be used in strategic management, entrepreneurship and general management courses/modules at the Undergraduate and Postgraduate level.

The purpose of this paper is to describe the application of low‐glitch current cell in a digital to analog converter (DAC) to reduce the clock‐feedthrough effect and achieve a low power consumption.

A low‐glitch current switch cell is applied in a ten‐bit two‐stage DAC which is composed of a unary cell matrix for six most significant bits and a binary weighted array for four least significant bits (LSBs). The current cell is composed of four transistors to neutralize the clock‐feedthrough effect and it enables DAC to operate in good linearity and low power consumption. The prototype DAC is being implemented in a 0.35μm complementary metal‐oxide semiconductor process. The reduction in glitch energy and power consumption has been realized by preliminary experiment and simulation.

Compared to conventional current cell, more than 15 per cent reduction of glitch energy has been obtained in this work. The DAC is estimated that differential nonlinearity is within 0.1 LSB and the maximum power consumption is 68 mW at the sampling frequency of 100 MHz.

Comparison with other conventional work indicates that the current cell proposed in this paper shows much better performance in terms of switching spike and glitch, which may come from the extra dummy transistor in cell and reduce the clock‐feedthrough effect.

Rework is an integral part of printed circuit board assembly (PCBA) manufacturing. However, the state‐of‐the‐art for PCBA rework still relies on operator activity and is therefore semi‐automatic. As a result, the quality of rework depends very much on the skill of the operator. When developing an automatic PCBA rework cell, the cell controller is an essential part which organises and controls the overall rework operation. This paper describes the software modelling of the cell controller for the PCBA rework cell which has been implemented for reworking through‐hole and surface mounted components. The software model is based on hybrid representations and rule‐based control.

Small cells, or microcells, are often seen as a way to substantially enhance the capacity of cellular networks. Previous assumptions have been that by deploying a dense layer of small cells within a macrocell, capacity can be improved by an order of magnitude or more. However, there are complexities such as the need to share frequencies between macrocell and small cells, varying patterns of users, the balance between indoor and outdoor subscribers and the different options available within 4G for balancing loading. The purpose of this study is to understand the impact these real-world constraints have on the capacity enhancements that small cells can provide.

This paper describes a model that simulates the impact of small cell deployments in macrocells in a typical 4G network.

It shows that, in some cases, small cells can actually reduce capacity, while in the best case, maximum capacity gains are less than 100 per cent.

It shows that, in some cases, small cells can actually reduce capacity contrary to perceived wisdom.

The purpose of this paper is to investigate a light-trapping structure based on Ag nanograting for amorphous silicon (a-Si) thin-film solar cell. Silver nanopillar arrays on indium tin oxide layer of the a-Si thin-film solar cells were designed.

The effects of the geometrical parameters such as nanopillar radius (R) and array period (P) were investigated by using the finite element simulation.

The optimization results show that the absorption of the solar cell with Ag nanopillar structure and anti-reflection film is enhanced up to 29.5 per cent under AM1.5 illumination in the 300- to 800-nm wavelength range compared with the reference cell. Furthermore, physical mechanisms of absorption enhancement at different wavelength range are discussed according to the electrical field amplitude distributions in the solar cells.

The research is still in progress. Further studies mainly focus on the performance of solar cells with different nanograting materials.

This study provides a feasible method for light-trapping structure based on Ag nanograting for a-Si thin-film solar cell.

This study is promising for the design of a-Si thin-film solar cells with enhanced performance.

Functional plant layouts are normally adopted in organizations that manufacture large varieties of components in low annual volumes. Attempts to improve the efficiency of these layouts have normally focused on the identification and implication of group technology cells which process a limited range of parts using flow process principles. Cell layouts provide the condition for kanban control procedures to operate, hence the benefits of just‐in‐time can be achieved in batch processing environments. However, in high variety/low volume (HV/LV) environments there is often insufficient commonality between part types to justify the formation of cells. Describes an alternative plant layout procedure (process sequence cell layout) currently being developed that allocates equipment to cells according to their position in the process routes of components. Uses a case study to illustrate how such a layout may be identified for an organization that has a typical high variety/low volume environment. Discusses the problems that need to be overcome if such systems are to be implemented and offers a description of how integrated MRP II/kanban control mechanisms can be used to control production.