Osvaldo Querin

University of Leeds · School of Mechanical Engineering

A surrogate-enabled multi-objective optimisation methodology for a continuous flow Polymerase Chain Reaction (CFPCR) systems is presented, which enables the effect of the applied PCR protocol and the channel width in the extension zone on four practical objectives of interest, to be explored. High fidelity, conjugate heat transfer (CHT) simulations...

The development of Polymerase Chain Reaction Mullis et al. in 1986 [1] (PCR) has played an important role in the progress of molecular diagnostics, enabling the rapid DNA amplification through a series of repeated cycles. Considering the wide use of PCR devices in research, there is a great need to optimize their performance. This study focuses on...

This article presents an infill topology optimization procedure to generate lightweight porous structures. The proposed method is based on discrete variables and builds upon the sequential element rejection and admission method, extending previous work on topology optimization for infill structures. Local volume constraints are introduced in the co...

Polymerase Chain Reaction (PCR) is widely used in biological research labs in order to detect hereditary diseases, diagnose infectious diseases, clone genes and other purposes. This work focuses on combining CFD and response surface modelling to explore the dependence of DNA amplification on two design parameters in a single phase, continuous flow...

A novel Computational Fluid Dynamics-enabled multi-objective optimisation methodology for Polymerase Chain Reaction flow systems is proposed and used to explore the effect of geometry, material and flow variables on the temperature uniformity, pressure drop and heating power requirements, in a prototype three-zone thermal flow system. A conjugate h...

The invention and development of Polymerase Chain Reaction (PCR) technology have revolutionised molecular biology and molecular diagnostics. There is an urgent need to optimise the performance of these devices while reducing the total construction and operation costs. This study proposes a CFD-enabled optimisation methodology for continuous flow (C...

jats:p>The invention and development of Polymerase Chain Reaction (PCR) technology have revolutionised molecular biology and molecular diagnostics. There is an urgent need to optimise the performance of these devices while reducing the total construction and operation costs. This study proposes a CFD-enabled optimisation methodology for continuous...

This paper presents an infill topology optimization procedure to generate lightweight porous structures by the Sequential Element Rejection and Admission (SERA) method. The proposed procedure evaluates the material volume of small neighbourhoods guaranteeing the presence of material within each of them by means of a set of local volume constraints....

The rotational behaviour of three-dimensional steel end-plate connections can be studied using the finite element method for the following four reasons: (1) such models are inexpensive and robust; (2) they allow the understanding of local effects; (3) they can be used to generate extensive parametric studies; (4) current version of the component me...

This paper presents the Matlab implementation of the Sequential Element Rejection and Admission (SERA) method for topology optimization of structures and compliant mechanisms. The lines comprising this code include definition of design domain, finite element analysis, sensitivity analysis, mesh-independency filter, optimization algorithm and displa...

A wide range of topology optimization methods have been developed for structural topology optimization where the individual finite elements are used as the design variables. Such methods include: Homogenization, Solid Isotropic Microstructure with Penalization Method (SIMP), Computer-Aided Optimization (CAO); Hard-Kill and Soft-Kill; Evolutionary S...

This chapter presents the Isolines/Isosurfaces Topology Design (ITD) method which allows for the continuous optimization of the topology of a structure. For a two-dimensional (2D) domain, ITD uses the isolines, and for a three-dimensional (3D) domain, it uses the isosurfaces of the response used for the optimization of the structure. The topology a...

This book presents three topology optimization methods together with examples and explanations of how topology optimization is a powerful tool for the design of structures. It also includes three software tools which allow the reader to try for themselves the three presented topology optimization methods. Two are standalone programs and the third r...

Topology optimization has emerged as a powerful and useful tool for the design of structures, a contributing factor being the emergence of computational speed and power. The design process has also been affected by computers which have changed the concept of form into the concept of formation and the emergence of digital design. Topology optimizati...

The problem of optimally designing the topology of plane trusses in most cases has been dealt with as a size problem, where bars are eliminated when their size approaches zero. This chapter presents a growth method for the optimal design of statically determinate plane truss structures. It uses a sequential process of topology, followed by geometry...

This chapter presents an overview of structural optimization, explaining briefly the different types which include size, shape, and topology optimization. This book aims to present to the reader the different methods of topology optimization developed by the authors, so this chapter serves as an introduction to topology optimization methods, some o...

The paper reports on an intervention crossover study with repeated measures with two different prosthetic knees during two weeks adaptation period over the ground walking. The heel linear velocities of a transfemoral amputee (TFA) was measured to evaluate possible gait deficiency during heel-contact (HC). The result showed that during late swing ph...

Topology Design Methods for Structural Optimization provides engineers with a basic set of design tools for the development of 2D and 3D structures subjected to single and multi-load cases and experiencing linear elastic conditions. Written by an expert team who has collaborated over the past decade to develop the methods presented, the book discus...

Bi-axially strained Germanium (Ge) is an ideal material for Silicon (Si) compatible light sources, offering exciting applications in optical interconnect technology. By employing a novel suspended architecture with an optimum design on the curvature, we applied a biaxial tensile strain as large as 0.85% to the central region of the membrane.

Bi-axially strained Germanium (Ge) is an ideal material for Silicon (Si) compatible light sources, offering exciting applications in optical interconnect technology. By employing a novel suspended architecture with an optimum design on the curvature, we applied a biaxial tensile strain as large as 0.85% to the central region of the membrane.

Over the past few decades, topology optimization has emerged as a powerful and useful tool for the design of structures, also exploiting the ever growing computational speed and power. The design process has also been affected by computers which changed the concept of form into the concept of formation and the emergence of digital design. Topology...

The paper reports on an intervention crossover study with repeated measures with two different prosthetic knees during two weeks adaptation period over the ground walking. The heel linear velocities of a transfemoral amputee (TFA) was measured to evaluate possible gait deficiency during heel-contact (HC). The result showed that during late swing ph...

This paper provides guidelines to estimate the kinematics, energy and torque requirements for lower limb prosthetic actuation systems during daily living activities. These parameters are estimated based on human biomechanical data from different sources to consider the variability due to the assumptions and errors in the analysis and data collectio...

This work presents a sequential element rejection and admission (SERA) method for optimum topology design of three dimensional compliant actuators. The proposed procedure has been successfully applied to several topology optimization problems, but most investigations for compliant devices design have been focused on planar systems. This investigati...

This work presents a sequential element rejection and admission (SERA) method for optimum topology design of three dimensional compliant actuators. The proposed procedure has been successfully applied to several topology optimization problems, but most investigations for compliant devices design have been focused on planar systems. This investigati...

The loss in mobility following amputation results in a degradation of the quality of life of the amputees as it affects many aspects of their personal and professional lives. Lower limb prostheses are used to replace the lost limbs and assist amputees in restoring their missing mobility functions. Despite the current technological advances in prost...

In this paper, a lamination parameter-based approach to weight optimization of composite aircraft wing structures is addressed. It is a bi-level procedure where at the top level lamination parameters and numbers of plies of the pre-defined angles (0, 90, 45 and −45°) are used as design variables, the material volume is treated as an objective funct...

A heterogeneous or multi-material object is one made from different materials which are distributed continuously or discontinuously. Its properties can be adjusted by controlling the material composition, microstructure and geometry of the object. The development of manufacturing technologies such as rapid prototyping can eliminate the high cost of...

This paper presents the kinematics, energy and torque requirements for prosthetic knee actuation system. These parameters are estimated based on human biomechanical data.

A generalized formulation to design Multi-Input–Multi-Output (MIMO) compliant mechanisms is presented in this work. This formulation also covers the simplified cases of the design of Multi-Input and Multi-Output compliant mechanisms, more commonly used in the literature. A Sequential Element Rejection and Admission (SERA) method is used to obtain t...

The SERA method was extended to the design of compliant mechanisms. This method allows material to be added and removed from the design domain until the optimum topology is reached. The main difference with respect to other bi-directional methods that add and remove elements from the design domain is the separate treatment of ‘real’ and ‘virtual’ m...

The SERA method was extended to the design of compliant mechanisms. This method allows material to be added and removed from the design domain until the optimum topology is reached. The main difference with respect to other bi-directional methods that add and remove elements from the design domain is the separate treatment of ‘real’ and ‘virtual’ m...

The design of multi-material compliant mechanisms by means of a multi Sequential Element Rejection and Admission (SERA) method is presented in this work. The SERA procedure was successfully applied to the design of single-material compliant mechanisms. The main feature is that the method allows material to flow between different material models. Se...

Additive manufacturing, more commonly known as 3D printing is a rapidly developing, thoroughly novel means of producing complex, previously difficult to manufacture components. Slowly divorcing itself from previously held preconceptions of rapid prototyping and now capable of producing comparable structures from materials such as titanium and high...

Additive manufacturing, more commonly known as 3D printing is a rapidly developing, thoroughly novel means of producing complex, previously difficult to manufacture components. Slowly divorcing itself from previously held preconceptions of rapid prototyping and now capable of producing comparable structures from materials such as titanium and high...

The discrete methods such as ESO/AESO/BESO/SERA methods are some of the topology optimization methods that contributed to the rapid expansion of the optimization field. Between the different approaches, an issue that remains unstudied is the key difference between the two strategies to add and remove material that can be found in the literature for...

Conventional commercial aircraft fuselages use all-aluminium semi-monocoque structures where the skin carries the external loads, the internal fuselage pressurisation and is strengthen using frames and stringers. Environmental and economic issues force aircraft designers to minimise weight and costs to keep air transport competitive and safe. But a...

Thin-walled shell structures are extensively used in architecture and engineering owing to their light weight and ease of shaping. But they suffer from poor overall stiffness, something addressed by the strategic addition of stiffeners. The optimization of stiffeners is divided between those that include shell membrane in the optimization and those...

A Sequential Element Rejection and Admission (SERA) method to design compliant mechanisms with topology optimization techniques is presented in this work. This procedure allows material to flow between two different material models: ‘real’ and ‘virtual’. The method works with two separate criteria for the rejection and admission of elements to effi...

Broad spectrum mission capability for minimal cost is a critical objective for many systems undergoing design and development for use in modern theaters. Through utilization of combinatory and mutually beneficial technologies, a technique has been developed and demonstrated which allows for optimized mission performance characteristics to be achiev...

Multiple topology optimization methods for structural optimization problems can be found in the literature. Among this wide range is the sequential element rejection and admission (SERA) method for fully stressed design. This procedure allows material to flow between two different material models: 'real' and 'virtual'. It works with two separate cr...

Considerable efforts were made in the past 15 years to develop strategies for the optimization of steel frames with semi-rigid connections, concentrating on the frames and not the connections, which were designed after the rest of the structure had been optimized. The analysis of semi-rigid connections requires the calculation of the moment-rotatio...

The presentation reports on results of a conceptual design phase of a collaborative research programme aiming at the development of manufacture-optimized lattice fuselage structures satisfying fundamental requirements of airworthiness. It will be shown how topology optimization was used to analyse different load cases and maximize the stiffness of...

With ever increasing economic and environmental drivers, the commercial aviation industry has embraced the use of topology optimization (TO) as a means of reducing the structural mass of large assemblies in many aircraft projects. However, large assemblies and even large parts suitable for optimization in isolation on any civil airliner are relativ...

This paper explores the issues related to the application of fuzzy logic techniques to aid the process of weight estimation for aircraft structures at preliminary design stages. The focus lays on the design of a neuro-fuzzy system for the weight analysis, through the use of the Neuro-Fuzzy Function Approximator (NEFPROX) algorithm. The paper introd...

Isolines Topology Design (ITD) is an iterative algorithm for the topological design of two-dimensional continuum structures using isolines. This paper presents an extension to this algorithm for topology design of three-dimensional continuum structures. The topology and the shape of the design depend on an iterative algorithm, which continually add...

The Strut-and-Tie Method is considered a basic tool for analysis and design of reinforced concrete structures and has been incorporated in different codes of practice such as: EC-2, BS 8110, ACI 318-08, EHE-08, etc. The stress trajectories or load path methods have been used to generate strut-and-tie models. However, the models produced by these me...

Steel portal frames were traditionally designed assuming that beam-to-column joints are ideally pinned or fully rigid. This simplifies the analysis and structural design processes, but at the expense of not obtaining a detailed understanding of the behaviour of the joints, which in reality, have finite stiffness and are therefore semi-rigid. The la...

The literature on the topology optimization of truss-like continua has relatively few publications that look at the problem of structures with different material properties/behaviour in tension and compression. After reviewing the literature on optimality criteria, ground structure approach, growth method for truss structures, SIMP, homogenization...

The smeared stiffness-based method is examined for finding the best stacking sequence of laminated composite wing structures with blending and manufacturing constraints. In this method, numbers of plies of the pre-defined angles (0, 90, 45 and -45 degrees) are design variables, buckling, strain and ply angle percentages are constraints and the mate...

Isolines topology design (ITD) is an iterative algorithm for the topological design of two-dimensional continuum structures using isolines. This paper presents an extension to this algorithm for topology design under multiple load cases of two/three-dimensional continuum structures. The topology and the shape of the design depend on an iterative al...

In this chapter the use of Genetic Algorithms and Genetic Programming for various industrial problems is discussed. Particular attention is paid to the case of difficult design optimization problems in which either (or both) (i) response functions are computationally expensive as well as affected by numerical noise and (ii) design variables are def...

The smeared stiffness-based method is examined for finding the best stacking sequence of laminated composite wing structures in a bi-level optimization process with blending and manufacturing constraints. At the global level optimization, the numbers of plies of the pre-defined angles (0, 90, 45 and -45 degrees) are design variables, buckling, stra...

Two approaches are examined for finding the best stacking sequence of laminated composite wing structures with blending and manufacturing constraints: smeared-stiffness-based method and lamination-parameter-based method. In the first method, the material volume is the objective function at the global level, and the stack shuffling to satisfy blendi...

This paper presents the algorithm for the topological design of two-dimensional structures using isolines called isolines topology design (ITD). The topology and the shape of the design depend on an iterative algorithm, which continually adds and removes material depending on the shape and distribution of the contour isolines of the required struct...

Weight estimation in aircraft design is very challenging due to the high number of variables involved in the creation of an accurate weight model, the numerous relationships between them and the high degree of uncertainty associated with the problem itself. This paper discusses a preliminary study on the use of fuzzy logic as an aid to the knowledg...

This paper presented the "Top-Down" design of a com-putational framework for multiphysics simulation and optimiza-tion of MEMS devices. This framework couples various existing phenomena-specific single-physics tools–each specialized for a most appropriate physical domain–into an integrated architec-ture, which allows MEMS designers to predict the b...

Due to the growing demands from industries, the multiphysics simulation plays a more and more important role in the design of MEMS devices. This paper presents a fast convergence scheme which implements multiphysics simulation by coupling phenomena-specific single-physics solvers. The proposed scheme is based on the traditional staggered/relaxation...

This paper details the development of the fixed grid FEA (FGFEA) method to the solution of eigenvalue (natural frequency and buckling) problems, using a 4 node 20 degree of freedom shell element. The formulation of the FG element stiffness, buckling and natural frequency equations is presented. The first natural frequency and buckling load are dete...

The problem of optimally designing the topology of plane trusses has, in most cases, been dealt with as a size problem in which members are eliminated when their size tends to zero. This article presents a novel growth method for the optimal design in a sequential manner of size, geometry, and topology of plane trusses without the need of a ground...

Various types of benchmark examples for optimal structural topologies are critically examined and an extensive literature survey of existing exact analytical solutions presented. New classes of analytical solutions, including some popular benchmark problems, are illustrated with examples. Finally, quality control methods for examining the validity,...

This paper presents a structural optimisation method using the genetic programming (GP) technique. This method applied linear GP to derive optimum geometry and sizing of discrete structure from an arbitrary initial design space. The linear GP was used to find out the optimum nodal locations and member sizing of the structure through a linear sequen...

This note deals with topological optimization of structures in which some members or elements of given cross-section exist prior to design and new members are to be added to the system. Existing members are costless, but new members and additions to the cross-section of existing members have a non-zero cost. The added weight is minimized for given...

The aim of this paper is to discuss some issues of pivotal importance in topology optimization, which receive inadequate attention in the literature.

Due to the massive demands from industry, the black-box based coupled energy domains simulation plays a more and more important role in the design of MEMS devices, and many numer-ical techniques have been developed so far for it. This paper presents a fast convergence scheme for coupled energy domains simulation of MEMS. This scheme is based on the...

Structural shape optimisation is a process of changing the structural boundary to reach to an optimum design (i.e. minimum weight, low cost, etc.) while satisfying the structural geometry (i.e. height, radius, etc.) and behaviour (i.e. stress, natural frequency, etc.) constraints. These problems can be solved by either calculus or heuristic-based m...

This paper presents a new self adaptive correction function for the optimisation of size, geometry and topology of space truss structures using the Genetic Algorithm (GA) method, applied to both continuous and discrete design variables. This function guarantees the diversity of the population at the early stages of the optimisation process. In addi...

This paper details the development and incorporation of an 8 node cubic brick element into the Fixed Grid Finite Element Analysis (FGFEA) method, for the solution of 3D problems. The formulation of the Fixed Grid (FG) element stiffness equations is presented and the expected computational efficiency benefits of the method are stated. An initial eva...

The success of GA-based topology optimisation methods for continuum structures has been limited. Though a number of methods exist, the results are far from comparable to solutions from more established methods in terms of quality and fidelity. This had led many structural optimisation researchers to dismiss the GA as a viable method for topology op...