Search results

Structural topology optimization is computationally expensive due to the involvement of high-resolution mesh and repetitive use of finite element analysis (FEA) for computing the structural response. Since FEA consumes most of the computational time in each optimization iteration, a novel GPU-based parallel strategy for FEA is presented and applied to the large-scale structural topology optimization of 3D continuum structures.

A matrix-free solver based on preconditioned conjugate gradient (PCG) method is proposed to minimize the computational time associated with solution of linear system of equations in FEA. The proposed solver uses an innovative strategy to utilize only symmetric half of elemental stiffness matrices for implementation of the element-by-element matrix-free solver on GPU.

Using solid isotropic material with penalization (SIMP) method, the proposed matrix-free solver is tested over three 3D structural optimization problems that are discretized using all hexahedral structured and unstructured meshes. Results show that the proposed strategy demonstrates 3.1× –3.3× speedup for the FEA solver stage and overall speedup of 2.9× –3.3× over the standard element-by-element strategy on the GPU. Moreover, the proposed strategy requires almost 1.8× less GPU memory than the standard element-by-element strategy.

The proposed GPU-based matrix-free element-by-element solver takes a more general approach to the symmetry concept than previous works. It stores only symmetric half of the elemental matrices in memory and performs matrix-free sparse matrix-vector multiplication (SpMV) without any inter-thread communication. A customized data storage format is also proposed to store and access only symmetric half of elemental stiffness matrices for coalesced read and write operations on GPU over the unstructured mesh.

Parts that are to be used in aircraft, satellites, automobiles and ships should have sound microstructure. Components made from AA6082/Si₃N₄ and AA6082/SiC composites are in demand from industries. Hence, these components are to be fabricated by suitable technique at the appropriate value of process parameters. The purpose of this paper is Microstructure analysis of AA6082/Si3N4 and AA6082/SiC composites

AA6082/Si₃N₄ and AA6082/SiC composites are successfully fabricated using the stir casting process. Their microstructures have been analyzed. This has been done at different magnification. The effect of the addition of Si₃N₄ and SiC particles in the 6082 aluminum alloy is investigated. Microstructure of AA6082/Si₃N₄ and AA6082/SiC composites are also compared. Results show that Si₃N₄ and SiC particles have good wettability with AA6082. These reinforcement particles are homogeneously distributed in the matrix of AA6082.

There are no adverse effects of reactions in the microstructure of AA6082/Si₃N₄ and AA6082/SiC composites. There is not much difference between the distribution and interfacial characteristics of Si₃N₄ and SiC particles. AA6082/Si₃N₄ and AA6082/SiC composites have good properties. This is high strength at low density. Due to which they become suitable for the aircraft and space industry. So far, SiC, Al₂O₃ and tungsten carbide have been mostly used as reinforcements with different grades of aluminum alloy.

Not much experimental work is found with Si₃N₄ and SiC particles as reinforcement with AA6082. The novelty of this research work is that an effort has been made to fabricate AA6082/Si₃N₄ and AA6082/SiC composites at such values of process parameters, by stir casting process, so that sound and defect free microstructure is obtained. Microstructure of AA6082/Si₃N₄ and AA6082/SiC composites is also compared, to find which is better.

Sound microstructure components are necessary for reliability and safety; hence, these components are used in aircraft, satellite, automobiles and ships, where many commercial alloys are not suitable. The paper aims to discuss this issue.

AA6082/Si₃N₄ and AA6082/SiC composites were fabricated using the stir-casting process considering 5, 10 and 15 vol.% of reinforcement particles. Density and porosity of AA6082/Si₃N₄ and AA6082/SiC composites were calculated. Characterization was done using an X-ray (EDX) detector, attached to SEM. The effect of addition of Si₃N₄ and SiC particulates in the AA6082 was investigated.

Results showed that Si₃N₄ and SiC particulates had good wettability with AA6082 and were uniformly distributed in AA6082 matrix. No adverse effects of reactions were noticed in the microstructure of AA6082/Si₃N₄ and AA6082/SiC composites.

AA6082 with more than 15 vol.% of Si₃N₄ and AA6082/SiC reinforcement particles do not find industrial application where high hardness and tensile strength are required.

Components made from AA6082/Si₃N₄ and AA6082/SiC composites find their application where high hardness with better tensile strength is required.

Naturally and locally available materials are utilized for fabrication.

Little work is available in the literature on fabrication and characterization of AA6082/Si₃N₄ and AA6082/SiC composites. The authors have identified the process parameters at which proper fabrication is done and sound microstructure is obtained.

The purpose of this paper is to show that some of the critical questions that top executives from electronics companies ask are not unique to their industry and, in fact, are the same ones that confront executives across a variety of industries and virtually all company sizes. Questions that address issues of product complexity and the breadth of product offerings, how to respond to competitive forces, and how to meet the challenges that come from shortened product lifecycles and shrinking the time it takes for products to ultimately reach the marketplace are all relevant across multiple industries. Still, the electronics industry is one that is experiencing an especially unprecedented degree of change spurred by the increasing complexity of end products, higher competitive intensity, and shorter time to commoditization.

The article provides the methodology and tool set needed to develop and assess a product portfolio map, determine changes needed to marketing and sales focus as well as future actions to take in order to sustain higher profitability and return on investments. It includes: definition of the key dimensions and characteristics of the six key zones for product, sales, and marketing; summary of product, marketing and sales focus by zone; key challenges and actions that an organization can undertake for each zone; and methodology to apply the framework and develop an actionable transformation roadmap. This answers key questions such as: Does the current coverage align with existing core competencies? Which zone has the most profitable products? If playing in every zone which business should be divested? If there is heavy emphasis on one zone what does it mean for M&A strategy? Where do the top 100 customers map in the framework? What looking at product and technology roadmap going forward, which zones do we start entering?

This article provides a framework that enables businesses to ascertain their current state and identify actions appropriate to achieve a desired future state. It provides insights that lead to an actionable transformation plan.

Most companies in the electronics industry are executing multiple strategies based on acquisitions, sales transformations, new product introductions, and cost cutting measures to deal with the situation. However, the success rate of these strategies leaves significant room for improvement at many companies. So what is the answer? As is often the case when many variables need to be considered simultaneously and the competitive environment is complex such as this, it is important to establish a structured way to approach the challenges at hand. In this case, the key elements to consider are the customer experience, the product portfolios, and sales and marketing competencies. Achieving the right level of interaction and focus among these elements is critical to achieving success. This article provides a new and insightful framework to enable a structured analysis of the multi‐variable system.

In recognition of the urgency of the global need to reduce CO₂ emissions from the electricity sector, the purpose of this paper is to analyze the cost‐effectiveness of nuclear power and fossil‐fuel‐based power with and without the provision of carbon capture and storage in select, yet environmentally‐significant, group of countries – China, India, Russia, Korea, Pakistan, Poland, Argentina, Bulgaria and Romania.

The analyses are based on comparisons of electricity generation costs for nuclear and fossil‐fuel technologies. These costs, expressed in present value terms, are estimated on the basis of life‐cycle costs, employing detailed country‐specific technological and economic data and assumptions.

The analyses suggest that that the provision of carbon capture and storage is likely to result in a significant increase in the cost of electricity produced from fossil fuels (principally coal) in all countries represented in this paper. Such increase would completely erode the existing cost advantage enjoyed by fossil‐fuel power (in relation to nuclear power) in some countries (Argentina, Bulgaria, China, and India) and considerably enhance the existing cost‐advantage of nuclear power in other countries (Korea, Pakistan, Poland, Romania, and Russia).

Notwithstanding these limitations, the findings of this paper contribute appreciably to the emerging knowledge on this topic and provide useful foresight into the likely challenges of developing internationally acceptable policy prescriptions for mitigation CO₂ emissions from the electricity sector. At a mundane, yet important, level, this paper establishes a platform on which further analyses could be built.

This paper aims to detect abnormal energy uses which relate to undetected consumption, thefts, measurement errors, etc. The detection of irregular power consumption, with variation in irregularities, helps the electric utilities in planning and making strategies to transfer reliable and efficient electricity from generators to the end-users. Abnormal peak load demand is a kind of aberration that needs to be detected.

This paper proposes a Density-Based Micro Spatial Clustering of Applications with Noise (DBMSCAN) clustering algorithm, which is implemented for identification of ranked irregular electricity consumption and occurrence of peak and valley loads. In the proposed algorithm, two parameters, a and ß, are introduced, and, on tuning of these parameters, after setting of global parameters, a varied number of micro-clusters and ranked irregular consumptions, respectively, are obtained. An approach is incorporated with the introduction of a new term Irregularity Variance in the suggested algorithm to find variation in the irregular consumptions according to anomalous behaviors.

No set of global parameters in DBSCAN is found in clustering of load pattern data of a practical system as the data. The proposed DBMSCAN approach finds clustering results and ranked irregular consumption such as different types of abnormal peak demands, sudden change in the demand, nearly zero demand, etc. with computational ease without any iterative control method.

The DBMSCAN can be applied on any data set to find ranked outliers. It is an unsupervised approach of clustering technique to find the clustering results and ranked irregular consumptions while focusing on the analysis of and variations in anomalous behaviors in electricity consumption.

In the early 1990s, the Thai government initiated a process of reform of the electricity industry with the argument that such reform would improve the performance of the industry and contribute to enhancing the overall economic prosperity. The purpose of this paper is to examine the veracity of this argument by analysing both the technical and environmental performance of the Thai electricity industry.

A data envelopment analysis‐based methodology is employed in this study to measure the productivity of the Thai electricity industry, for the period 1980‐2006. This method enables the decomposition of productivity changes into technical and efficiency changes, and hence enables one to determine if changes in productivity are due to electricity reform (efficiency gains) or due to autonomous technological improvements.

The study reveals that the increase in the productivity of the Thai electricity industry over the period 1980‐2006 was mainly driven by technological improvements and that industry reform has had insignificant impact on productivity. Further, the impacts of electricity reform on the environment appear to be relatively modest – this too was driven by government regulation that supports the use of less environmentally detrimental fuels for electricity generation by the private producers, rather than electricity reform.

The analysis in this paper contributes to the literature on productivity and efficiency, by applying the DEA method to a time series data for a single industry. Additionally, the analysis of environmental performance of the Thai electricity industry – to the best of knowledge of the authors – is the first of its kind for the Thai electricity industry.