Numerous Prototypes Research Articles

Advanced numerical prototyping methods in modern engineering applications – Optimisation for micro-electronic package reliability

Numerical prototyping methods based on numerical simulations and optimisation technologies are nowadays a key success factor for cost effectively and timely development and manufacturing of competitive products and processes. The typical numerical prototyping procedures are based on a sequence of numerical simulations and/or experiments done in an iterative form in order to achieve (sub-)optimal designs. The ‘Design Of Experiments’ are usually selected according to the knowledge and experience of an engineer and/or defined according to certain numerical methods. The current paper describes our research and results of advanced numerical prototyping, specially focused on a novel ‘Design Of Experiment’ approach and a novel ‘Response Surface Modelling’ approach. These novel approaches are applied to an example in which a micro-electronic package is optimised to minimize the stress levels during processing and manufacturing of this component. It is shown that our novel approach leads to a substantial reduction of numerical experiments to obtain a certain accuracy of the response surface models. As such, the optimisation process is shortened and can be used to faster optimise the performance of products and/or process prior to major physical prototyping and manufacturing investments.

Neural Networks for Estimation of Scour Downstream of a Ski-Jump Bucket

The estimation of scour downstream of a ski-jump bucket has remained inconclusive, despite analysis of numerous prototypes as well as hydraulic model studies in the past. It is partly due to the complexity of the phenomenon involved and partly because of limitations of the traditional analytical tool of statistical regression. This paper addresses the latter part and presents an alternative to the regression in the form of neural networks. The depth of the scour hole developed along with its width and length is predicted using neural network models. A network architecture complete with trained values of connection weight and bias and requiring input of grouped parameters pertaining to discharge head, tail water channel depth, bucket radius, lip angle, and median sediment size is recommended in order to predict the depth, the location of maximum scour, as well as the width of scour hole. The neural network predictions have been compared with traditional statistical schemes. Although the common and simple feed forward back propagation network took a very long time to train as compared to some advanced schemes, it was found to impart equally reliable training as the latter. Use of causative variables in grouped forms was found to be more rewarding than that of their raw forms probably due to lesser scaling effect.

Towards numerical prototyping of labs-on-chip: modeling for integrated microfluidic devices

This review article presents an overview of some of the tools, techniques and applications of numerical simulation for integrated microfluidic devices. Provided is a broad overview of the different areas to which numerical techniques have been applied in the development of these devices from detailed studies of fundamental microfluidic problems (e.g., species mixing and sample dispersion) to unique approaches that take a more global overview of the entire system. While the majority of the work to date has been in these areas, also reviewed is some recent progress into other equally important areas of microscale transport such as thermal analysis and chemical reactivity and specificity. An overview of the advantages and disadvantages of common numerical techniques is also presented along with a brief discussion of some of the existing numerical tools, focusing on those best suited for microscale transport analysis. As microfluidic devices become increasingly complex, optimal fluidic and transport designs become more and more difficult to do experimentally. Thus, it is believed that future demand in the field will be for highly integrated simulation tools that allow users without a significant computational fluids background to “numerical prototype” highly integrated devices.

An Optimization-Based Approach for Facility Energy Management with Uncertainties

Effective energy management for facilities is becoming increasingly important in view of rising energy costs, the government mandate on reduction of energy consumption, and human comfort requirements. This paper presents a daily energy management formulation and the corresponding solution methodology for HVAC systems. The problem is to minimize the energy and demand costs through control of HVAC units while satisfying human comfort, system dynamics, load limit constraints, and other requirements. The problem is difficult in view of the facts that the system is nonlinear, time-varying, building-dependent, and uncertain and that the direct control of a large number of HVAC components is difficult. In this paper, HVAC setpoints are control variables developed on top of a direct digital control (DDC) system. A method that combines Lagrangian relaxation, neural networks, stochastic dynamic programming, and heuristics is developed to predict system dynamics and uncontrollable load and to optimize the setpoints. Numerical testing and prototype implementation results show that our method can effectively reduce total costs, manage uncertainties, and shed the load; is computationally efficient; and is significantly better than existing methods.

DNA-based therapeutics and DNA delivery systems: A comprehensive review

The past several years have witnessed the evolution of gene medicine from an experimental technology into a viable strategy for developing therapeutics for a wide range of human disorders. Numerous prototype DNA-based biopharmaceuticals can now control disease progression by induction and/or inhibition of genes. These potent therapeutics include plasmids containing transgenes, oligonucleotides, aptamers, ribozymes, DNAzymes, and small interfering RNAs. Although only 2 DNA-based pharmaceuticals (an antisense oligonucleotide formulation, Vitravene, (USA, 1998), and an adenoviral gene therapy treatment, Gendicine (China, 2003), have received approval from regulatory agencies; numerous candidates are in advanced stages of human clinical trials. Selection of drugs on the basis of DNA sequence and structure has a reduced potential for toxicity, should result in fewer side effects, and therefore should eventually yield safer drugs than those currently available. These predictions are based on the high selectivity and specificity of such molecules for recognition of their molecular targets. However, poor cellular uptake and rapid in vivo degradation of DNA-based therapeutics necessitate the use of delivery systems to facilitate cellular internalization and preserve their activity. This review discusses the basis of structural design, mode of action, and applications of DNA-based therapeutics. The mechanisms of cellular uptake and intracellular trafficking of DNA-based therapeutics are examined, and the constraints these transport processes impose on the choice of delivery systems are summarized. Finally, the development of some of the most promising currently available DNA delivery platforms is discussed, and the merits and drawbacks of each approach are evaluated.

Smart and Sequential Approach to Numerical Prototyping in Micro-Electronic Applications

Numerical prototyping methods based on numerical simulations are nowadays a key factor to successful cost effective and timely design for optimized products and processes. The typical prototyping procedure would be based on a sequence of numerical simulations/tests done in an iterative form in order to achieve usually sub-optimal designs. These tests are usually selected according to the knowledge and experience of an engineer or defined standard with little or no help from effective methodologies. In contrast, this paper presents the elaborated optimized approach to numerical prototyping based on smart and sequential algorithm. The major advantage of the presented approach is that it can improve the quality of the response model at a fraction of the number of experiments compared to the classical methodologies. Details of the methodology are presented along with a selected example concerning micro-electronic packaging.

Usability Evaluation of a Gui Prototype for a Ventilator Machine

Information presentation on the monitor screen of ventilator machines affects nurses' response and decision-making during ventilation treatment. The purpose of this study is to evaluate whether a new GUI (graphical user interface) prototype, the so-called circular display prototype can make deviations easy to detect. A numerical display prototype was made and used as a reference display in the evaluation. Six task scenarios that involved parameter changes were selected to simulate a real situation under volume control (VC) mode during ventilation treatment. Usability tests with the two display designs were carried out in a usability laboratory. Twenty medical nursing students participated as test subjects in the usability tests. The objective results showed that the graphical circular display had an advantage over the numerical display in interpreting parameter changes, but not in reducing the error rates for detecting the number of parameter changes or for forming an overall picture of the patient's situation. Furthermore, the circular display prototype did not improve the detection time. Although the majority of the test subjects preferred the graphical circular display, the results implied that several aspects of this prototype should be improved in a future development study.

Nonlinear programming in process modeling and design

In today’s competitive market, it is no longer practical to design by trial and error. Yet, this remains the normal practice, whether through the testing of numerous prototype designs or the simulations of these designs. Of course, the latter is preferred because it is cheaper, but there remains the issue of finding the best possible design. A trial-and-error approach simply does not address this task. In this paper, the authors describe their work combining computational process modeling and nonlinear programming to optimally design manufacturing processes.

Basin Modeling in Complex Area: Examples from Eastern Venezuelan and Canadian Foothills

Basin modeling aims at reconstructing the time evolution of a sedimentary basin in order to make quantitative predictions of geological phenomena leading to hydrocarbons accumulations. It accounts for porous medium compaction, heat transfer, hydrocarbon generation and fluid flow. Nevertheless, classical basin models handle simple geometry and are not usable in complex geometry area such as foothills. This is why, a numerical prototype Ceres, has been developed. This prototype is able to model three-phase flow in a 2D section of a basin, whose geometry changes through time accounting for deposition, compaction, erosion of the sediments, salt or mud creeping, and block displacement along faults. The classical flow chart to perform a case study is composed of three main steps. The first step is the building of the present day section. This is generally done with data coming from the seismic interpretation, wells, outcrops, and core data. At this stage, the section is generally balanced using software such as Locace. The second step is the restoration of the section. The section at present day is restored back in the past for each of the defined layer until the substratum is reached. In order to balance the section during time and to constrain the eroded parts of the section, we have to use a forward kinematic modeling tool such as Thrustpack. Thus, from a section restored with Locace before thrusting, the use of Thrustpack allows to construct intermediate sections during time, which are consistent from a kinematics point of view. The last step is the forward simulation. And, in order to solve the coupled equations that are generally used in basin models, we had to develop original numerical methods based on domain decomposition techniques. The previous methodology is the fruit of tests performed for an Alberta (Canada) transect and an eastern Venezuelan transect. When considering the origin of the fluids in the Oligocene sandstones of the El Furrial structure or in the Mississipian dolomite of the Canadian foothills, a general scenario of squeegee fluids is recognized. Before the flexuring and thrusting period, fluids are in equilibrium with the sediments. They are being continuously expelled toward the surface during the compaction related dewatering. Then, because of the tilting and thrusting with the deposition of synflexural sediments, an episode of squeegee fluid is created with flow along the stratification that can reach velocity of tens of kilometers per million of years. This squeegee episode stops when the thrusts of the considered area become active.

Ceres2d: a Numerical Prototype for Hc Potential Evaluation in Complex Area

Abstract-Ceres2D: A Numerical Prototype for HC Potential Evaluation in Complex Area-This paper deals with the Ceres prototype which is a basin model able to account for porous medium compaction, heat transfer, and hydrocarbon generation and migration. Furthermore, Ceres was designed to handle changing geometry through time as results of sedimentation, erosion, salt or mud creeping and block displacement along fault. The classical flow chart to perform a case study is composed of three main steps. The first step is the building of the present day section. This is generally done with data coming from the seismic interpretation, well data, field data and core data. The second step is the restoration of the section. Thus from the section at present day, the section is restored back in the past for each of the defined layer, and until the substratum is reached. The last step is the forward simulation. And, in order to solve the coupled equations that are generally used in basin models, we had to develop original numerical methods based on domain decomposition techniques. The Ceres prototype has now been used to study petroleum systems. It has been used to perform sensitivity studies on fault permeability in the Bolivian foothills and the Congo offshore. In the Gulf of Mexico, it allowed to study the impact of the salt tectonics on the hydrocarbon migration. More recently, the Ceres prototype has been tested, within the frame of the SubTrap consortium, in thrust areas such as the Canadian foothills and the Eastern Venezuelan foothills. For these last case studies, it has been beneficial that structural geologists were involved at all stages of the process.

Fault current limiter based on triggered vacuum switch

A new type of fault current limiter (FCL) based on triggered vacuum switch (TVS) is proposed in this paper. The TVS-based FCL (TFCL) is mainly composed of a capacitor, a current-limiting reactor connected with a capacitor in series and a TVS connected with a capacitor in parallel. With the TVS at off or on state, the whole TFCL behaves as a conventional series compensator or a fault current limiter, respectively. Numerical simulation and prototype experiment based on LC resonant test circuit show that it is feasible to develop TFCL.

Using numerical simulation with rapid prototyping and investment casting

This article presents an approach to making an aluminum automobile prototype by integrating numerical simulation and rapid prototyping into investment casting. Following the integrated prototype procedure, a sound aluminum (Al-Si-7Mg) manifold prototype with excellent contour and an acceptable surface finish was made with only one casting trial. This study indicated that the potential of the rapid prototyping-investment casting coupling could be more effective with the aid of integrated numerical simulation, and numerical optimization of the casting parameters aids in minimizing the risk of casting failure and avoiding the iterative casting trials.

Growth of fathead minnows in oilsand‐processed wastewater in laboratory and field

AbstractTwo waste products of Syncrude Canada Ltd. (SCL) oilsands mine are mature fine tailings (MFT), a toxic aqueous suspension of particles, organic acids, bitumen, and metals, and tailings pond water (TPW), a saline solution containing organic and inorganic contaminants. The chemical profiles of MFT interstitial water and TPW are very similar. Syncrude Canada has proposed disposing of MFT in constructed lakes, which would be lined with MFT and capped with clean water. As the MFT consolidates, MFT‐associated water would be released into the overlying watercap. Prototype ponds support fathead minnows (Pimephales promelas), but the long‐term viability of these populations is unknown. This study attempts to determine if exposure to MFT and TPW, a related waste product, affected growth of fathead minnow larvae in the laboratory and field. Laboratory larval growth bioassays (7 and 56 d) on whole effluent from numerous prototype ponds yielded no significant differences in dry weight, but one 7‐d bioassay showed reduced survival in two SCL sites. A 56‐d growth bioassay showed significant increases in length of fish exposed to SCL wastewater at 7 d but not at 28 or 56 d. Larvae exposed as embryos and then introduced into field mesocosms did display significant differences in dry weight. In this instance, fish exposed to wastewater were significantly larger during the laboratory portion of the test (initial), but after 21 d in a field mesocosm (final), they were similar in size or smaller than fish growing in nonprocessed water.

Inversion simultanée des données sismiques et des données de production

On utilise, pour l'interprétation des mesures de production aux puits, ainsi que pour l'interprétation des profils sismiques, des procédures d'inversion. Elles permettent d'essayer, à partir d'un modèle géologique maillé, de caler des simulations numériques sur des mesures de terrain, ceci en faisant varier les paramètres de ce modèle. Malheureusement, un manque de données permet souvent à plusieurs modèles de résoudre le problème inverse. La gestion des incertitudes devient alors complexe. Une nouvelle méthode est donc proposée pour inverser simultanément les deux modèles (sismique et gisement) afin de réduire le nombre de scénarios possibles. On se sert ici des relations de laboratoire pour relier la perméabilité absolue du milieu à son impédance acoustique. On ajoute alors de l'information aux deux problèmes inverses et on améliore ainsi considérablement les modèles. In fine, on cherche à fournir à l'ingénierie de gisement les moyens de prévoir le comportement des gisements pétroliers hétérogènes et d'évaluer l'incertitude inhérente à ces prévisions. Sont présentés dans cet article les problèmes et procédures mathématiques employées comme modèles directs et inverses, ainsi que des tests numériques validant la méthode.

An Improved Dynamic Model of Pneumatic Actuators

AbstractAn improved predictive model of pneumatic jacks is introduced in order to develop a component oriented model library for the numerical prototyping of pneumatic actuators. First, the valve orifices model is derived from the ISO standard as a function of the orifice opening. Then the gas chamber behaviour is modelled using a rigorous theoretical development of conservation laws. Consequently, no assumption is required concerning the evolution of the gas only being considered as ideal. A fix parameter convective model is found acceptable to define the heat exchange between the gas and the jack environment. Finally, a representation model of the internal jack friction is proposed including the influence of pressure and working quadrant on viscous and Coulomb effects. The simulation structure is then presented and the model is validated using a step by step procedure.

The role of computer aided engineering in the design optimization of exhaust after-treatment systems

The goals of employing computer aided engineering (CAE) tools have always been the improvement of product quality and the simultaneous reduction of the related time-to-market and development costs. The latter may be achieved when the optimization procedure is carried out without the need to construct and test numerous prototypes. CAE tools and methodologies, apart from the design phase, can also be employed for dedicated prediction and analysis purposes, with the intention to fully exploit the capabilities of the catalytic exhaust system. A set of fundamental CAE tools and the accompanying (CAE) methodology, aiming to assist the design optimization of catalytic exhaust systems for spark-ignition-engined vehicles, are presented. The set comprises the following individual cooperating modules: a transient exhaust system heat transfer code, a transient three-way catalytic converter (3W-CC) computer code with an accompanying kinetics tuning procedure, a 3W-CC database and an ageing assessment methodology. The CAE methodology may be exploited in the directions of exhaust system design and optimization, addressing the catalytic exhaust system as an entity that consists of interrelated components. In that context, specific examples of real practice are demonstrated. This methodology is already being extensively used by the authors in research and development of automotive exhaust after-treatment systems, with promising results.

Choice of drives for electric vehicles: a comparison between two permanent magnet AC machines

Most motors for electric vehicles are based on the DC machine, nevertheless, the brushless surface mounted permanent magnet AC machine seems to be a good alternative. The authors propose a method of design and a comparison of two types of brushless machine that takes into account the requirements for the propulsion of electric vehicles. Two types of AC machine are designed taking into account the limitations due to the limited voltage power supply in terms of the airgap magnetic field shape and the corresponding stator current waveforms. Finally, a very simple analytical optimal design is proposed and verified both by numerical simulations and prototypes realisation.

Automated sample preparation using membrane microtiter extraction for bioanalytical mass spectrometry

The development and application of membrane solid phase extraction (SPE) in 96-well microtiter plate format is described for the automated analysis of drugs in biological fluids. The small bed volume of the membrane allows elution of the analyte in a very small solvent volume, permitting direct HPLC injection and negating the need for the time consuming solvent evaporation step. A programmable liquid handling station (Quadra 96) was modified to automate all SPE steps. To avoid drying of the SPE bed and to enhance the analytical precision a novel protocol for performing the condition, load and wash steps in rapid succession was utilized. A block of 96 samples can now be extracted in 10 min., about 30 times faster than manual solvent extraction or single cartridge SPE methods. This processing speed complements the high-throughput speed of contemporary high performance liquid chromatography mass spectrometry (HPLC/MS) analysis. The quantitative analysis of a test analyte (Ziprasidone) in plasma demonstrates the utility and throughput of membrane SPE in combination with HPLC/MS. The results obtained with the current automated procedure compare favorably with those obtained using solvent and traditional solid phase extraction methods. The method has been used for the analysis of numerous drug prototypes in biological fluids to support drug discovery efforts. © 1997 John Wiley & Sons, Ltd.

Automated sample preparation using membrane microtiter extraction for bioanalytical mass spectrometry.

The development and application of membrane solid phase extraction (SPE) in 96-well microtiter plate format is described for the automated analysis of drugs in biological fluids. The small bed volume of the membrane allows elution of the analyte in a very small solvent volume, permitting direct HPLC injection and negating the need for the time consuming solvent evaporation step. A programmable liquid handling station (Quadra 96) was modified to automate all SPE steps. To avoid drying of the SPE bed and to enhance the analytical precision a novel protocol for performing the condition, load and wash steps in rapid succession was utilized. A block of 96 samples can now be extracted in 10 min., about 30 times faster than manual solvent extraction or single cartridge SPE methods. This processing speed complements the high-throughput speed of contemporary high performance liquid chromatography mass spectrometry (HPLC/MS) analysis. The quantitative analysis of a test analyte (Ziprasidone) in plasma demonstrates the utility and throughput of membrane SPE in combination with HPLC/MS. The results obtained with the current automated procedure compare favorably with those obtained using solvent and traditional solid phase extraction methods. The method has been used for the analysis of numerous drug prototypes in biological fluids to support drug discovery efforts.

Evolution of Generic Mathematical Models and Algorithms for the Surface Development and Manufacture of Complex Ducts

Complex ducts bound by developable surfaces can be obtained by cutting out the required developed shape on plane sheets and then wedge-bending or folding along certain lines called generators or rulings. The problem then reduces to the theoretical determination of the 2-D shape to be cut so that on folding along the rulings, the required 3-D surface is accurately obtained. The first step in the surface unfolding process is the determination of the parametric β-θ relationship between two adjacent cross-sections of the duct. The cross-sections of the duct can be planar or nonplanar and composed of conic or spline curve segments, placed anywhere in space. In this paper the requisite β-θ relationships of the most generic form have been derived and can be directly applied to any complex duct. Based on these relationships, an efficient and compact algorithm for surface-unfolding has also been derived. The application of this algorithm to numerous prototype cases has been shown. The theory has been verified by physical modelling of various ducts occurring in the field of hydroturbines, and now forms the basis of an Integrated CAD-CAM System.