Unstructured parallel grid generation.

The ultimate goal of this study is to develop a 'tool' by which large-scale unstructured grids for realistic engineering problems can be generated efficiently on any parallel computer platform. The adopted strategy is based upon a geometrical partitioning concept, where the computational domain is sub-divided into a number of sub-domains which are then gridded independently in parallel. This study focuses on three-dimensional applications only, and it implements a Delaunay triangulation based generator to generate the sub-domain grids. Two different approaches have been investigated, where the variations between them are limited to (i) the domain decomposition and (ii) the inter-domain boundary gridding algorithms only. In order to carry out the domain decomposition task, the first approach requires an initial tetrahedral grid to be constructed, whilst the second approach operates directly on the boundary triangular grid. Hence, this thesis will refer to the first approach as 'indirect decomposition method' and to the second as 'direct decomposition method'. Work presented in this thesis also concerns the development of a framework in which all different sub-algorithms are integrated in combination with a specially designed parallel processing technique, termed as Dynamic Parallel Processing (DPP). The framework adopts the Message Passing Library (MPL) programming model and implements a Single Program Multiple Data (SPMD) structure with a Manager/Workers mechanism. The DPP provides great flexibility and efficiency in exploiting the available computing resources. The framework has proved to be a very effective tool for generating large-scale grids. Grids of realistic engineering problems and to the order of 115 million elements, generated using one processor on an SGI Challenge machine with 512 MBytes of shared memory, will be presented

Synthesis and application of nano and micro-silica particles to enhance the mechanical proprieties of cement concrete

The purpose of the current research was to evaluate the influence of nano and micro silica on compressive strength properties of cement concrete. Silica nanoparticles of size around 350 nm are synthesized by Stober’s method using Tetra Ethyl Silicate (TEOS), Ethanol and ammonia solution. The synthesized silica particles are characterized using Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Four different batches of sixteen cubes each of dimension 150 mm x 150 mm x 150 mm were prepared by mixing the cement with nano and micro silica, Ultra pozzolana, fine and coarse aggregates by incorporating 0.8% CF 615. The first batch composed of cement, fine aggregate and coarse aggregate and 0.8% CF 615 was considered as a reference batch. Same mix design of proportion 1:1.4:2.1 was followed for remaining mixes by replacing 1% of cement by nano silica, micro silica and Ultra pozzolana. The compressive strength tests of the above mixes are measured using Universal Testing Machine and the results were compared with the control mix. The results demonstrated that the sample were prepared using Ultra pozzolana with 0.8% CF 615, was found to have better strength of 37.45 N/mm2 compared to other samples

Urgensi Literasi Digital dalam Menangkal Radikalisme pada Generasi Millenial di Era Revolusi Industri 4.0

In the era of the Industrial Revolution 4.0, which was marked by the massive development of information technology and the easy distribution of information without any filters. This study aims to explained the urgency of digital literacy in order to ward off radicalism in the millennial generation in the era of the Industrial Revolution 4.0. The method used in this research is literature review with content analysis techniques. The conclusion of this study is that digital literacy skills are very important in warding off radicalism and need to be developed in eight essential elements, namely cultural, cognitive, constructive, communicative, creative, critical, and civic. In addition, to improve digital literacy skills, Siberkreasi activities can be used. Hopefully, with the digital literacy skills of a digital user, namely the millennial generation, they can filter the information obtained and ensure its correctness first

“BAM”: a collaborative R&D project for the development of a simulation based solution for the design and manufacture of 3D woven composites

Breakthrough Aerospace Materials (BAM) is a collaborative R&D project based in the UK [1]; led by industry and co-funded by the British Government via the Innovate-UK under its Aerospace Technology Institute (ATI) R&T Programme. The overall objective of BAM is to develop a complete process that will enable aerospace industry (and others) to design and manufacture complex shaped components using 3D woven composites. This material offers great advantages particularly for producing lightweight structures with high resistance to impact loading and damage - yet, there is still no evidence of it been widely adopted by industry! It is agreed that one of the major reasons behind slow adoption of the 3D woven composites by industry is the lack of industrial simulation tools that can be used effectively by design and analysis engineers. A consortium consisting of 12 partners, involving 9 from industry and 3 from academia, was set up to work towards this goal over a period of three years. As it is less than a year since the kick-off of the project, this paper will mainly introduce the general approach for now - leaving the full demonstration of applying the developed technologies on industrial cases for follow up publications. However, a few independent illustration examples are still presented - while elaborating on the current status of development at various steps in the process and its associated challenges. The paper also aims to highlight the interdependence between industrial and academic partners for their success in pushing the required technology up the TRL (Technology Readiness Level) scale. Two leading CAE software developers (ESI Group and MSC Software) are involved in BAM, and both are working on developing their own strategy to tackle the problem. The paper will elaborate on the approach adopted by ESI in particular, which is aligned with its global strategy for providing virtual end-to-end solution for composites product development

Non-intrusive proper generalized decomposition involving space and parameters: application to the mechanical modeling of 3D woven fabrics

In our former works we proposed different Model Order Reduction strategies for alleviating the complexity of computational simulations. In fact we proved that separated representations are specially appealing for addressing many issues, in particular, the treatment of 3D models defined in degenerated domains (those involving very different characteristic dimensions, like beams, plate and shells) as well as the solution of parametrized models for calculating their parametric solutions. However it was proved that the efficiency of solvers based on the construction of such separated representations strongly depends on the affine decompositions (separability) of operators, parameters and geometry. Even if our works proved that different techniques exists for performing such beneficial separation prior of applying the separated representation constructor, the complexity of the solver increases in certain circumstances too much, as the one involving the space separation of complex microstructures concerned by 3D woven fabrics. In this paper we explore an alternative route that allows circumventing the just referred difficulties. Thus, instead of following the standard procedure that consists of introducing the separated representation of the unknown field prior to discretize the models, the strategy here proposed consists of proceeding inversely: first the model is discretized and then the separated representation of the discrete unknown field is enforced. Such a procedure enables the consideration of very complex and non separable features, like complex domains, boundary conditions and microstructures as the ones concerned by homogenized models of complex and rich 3D woven fabrics. It will be proved that such a procedure can be also easily coupled with a non-intrusive treatment of the parametric dimensions by using a sparse hierarchical collocation technique

The influence of various chemical oxygen demands on microbial fuel cells performance using leachate as a substrate

Microbial fuel cells (MFCs), hailed as a promising technology, hold the potential to combat various wastewater pollutants while simultaneously converting their chemical energy into electricity through biocatalysts. This study explores the applicability of a dual compartment MFC (DC-MFC) under varying conditions, targeting the removal of chemical oxygen demand (COD) from landfill leachate and electricity generation. In this setup, anaerobic sludge from a wastewater treatment plant serves as the inoculum in the anode compartment of the MFC, with a Nafion117 membrane acting as the separator between MFC units. The cathode compartments are filled with distilled water and continually aerated for 24 h to enhance air supply. The study assesses the MFC's performance across different COD concentrations, focusing on COD removal, power generation, and Coulombic efficiency. The findings reveal that COD removal efficiency is notably enhanced at higher concentrations of organic matter. Specifically, at a COD concentration of 3325.0 mg L , the MFC exhibited the highest COD removal efficiency (89%) and maximum power density (339.41 mWm ), accompanied by a Coulombic efficiency of 25.5%. However, as the initial substrate concentration increased to 3825 mg L , the efficiency decreased to 72%, with a Coulombic efficiency of 13.56% and a power density of 262.34 mWm . Optical density levels increased due to bacterial growth at ambient temperature and neutral pH, reflecting the dynamic microbial response within the system. [Abstract copyright: © 2024. Crown.

Perfect secret sharing scheme based on vertex domination set

Due to the fast development in data communication systems and computer networks in recent years, the necessity to protect the secret data has become extremely imperative. Several methods have been proposed to protect the secret data; one of them is the secret sharing scheme. It is a method of distributing a secret K among a finite set of participants, in such a way that only predefined subset of participant is enabled to reconstruct a secret from their shares. A secret sharing scheme realizing uniform access structure described by a graph has received a considerable attention. In this scheme, each vertex represents a participant and each edge represents a minimum authorized subset. In this paper, an independent dominating set of vertices in a graph G is introduced and applied as a novel idea to construct a secret sharing scheme such that the vertices of the graph represent the participants and the dominating set of vertices in G represents the minimal authorized set. While most of the previous schemes were based on the principle of adjacent vertices, the proposed scheme is based upon the principle of non-adjacent vertices. We prove that the scheme is perfect, and the lower bound of the information rate of this new construction is improved when compared to some well-known previous constructions. We include an experiment involving security threats to demonstrate the effectiveness of the proposed scheme

Exploring the L2 motivational self system of Chinese English language learners

L2 motivation research has witnessed great development during recent decades. To re-conceptualize, the ‘integrativeness’ of the traditional socio-educational model, Dörnyei (2005) proposed the L2 motivational self system for better understanding and predicting L2 motivation. Therefore, the theory of Dornyei’s L2 Motivational Self System was employed to investigate the English learning motivation of L2 learners in China context by conducting a qualitative study. The data were collected from eight Chinese university students by semi-structured interviews. It revealed that the ideal L2 self, ought-to L2 self and L2 learning experience all contributed to the intended learning efforts of L2 learners. Overall, the current study provided empirical and qualitative evidence to support the construct of Dörnyei’s L2 Motivational Self System in China context

Characterisation of the contact pressure dependent interfacial heat transfer coefficient for a hot stamping process following a data driven approach

In the present research, the contact pressure characteristics of a hot stamping process was revealed by data mining an existing data base of verified FE simulation results, collected by a cloud-based finite element (FE) simulation platform. Following a data driven approach, a dedicated, novel testing scheme for a hot stamping process was developed and applied to determine the effect of contact pressure on the interfacial heat transfer coefficient (IHTC) between an AA7075 aluminium alloy and cast-iron tools. In this novel testing scheme, only one single IHTC test was required which has improved testing efficiency significantly