bluuebunny/crossref_metadata_2025 huggingface dataset:
Free Vibration of Bimodulus Laminated Cross-Ply Conical Panels
Authors: Khan K. , Patel B. P. , Nath Y.
Published: July 2009

The problem is formulated employing first order shear deformation theory. The governing equations, obtained using Lagrange’s equation of motion, are solved by finite element method. A detailed parametric study is carried out to study the influences of thickness ratio, aspect ratio, semicone angle, and number of layers on the free vibration natural frequencies and neutral surface location of bimodulus cross-ply composite laminated conical panels.
The Problem of Distributed Wireless Sensors Positioning in the Mobile Spatial Coordinate Measuring System (MSCMS)
Authors: Franceschini Fiorenzo , Galetto Maurizio , Maisano Domenico , Mastrogiacomo Luca
Published: July 2009

Mobile Spatial coordinate Measuring System (MScMS) is a wireless-sensor-network based system developed at the Industrial Metrology and Quality Engineering Laboratory of DISPEA – Politecnico di Torino. It has been designed to perform simple and rapid indoor dimensional measurements of medium-large size objects (large scale metrology). It is made up of three basic parts: a “constellation” of wireless devices (Crickets), a mobile probe, and a PC to store and elaborate data. Crickets and mobile probe use ultrasound (US) transceivers in order to evaluate mutual distances. Each US device has a communication range limited by a cone of transmission within a nominal opening angle of about 170° and a maximum distance of no more than 8 m. The mobile probe location in the working volume is obtained by a trilateration, consequently it should communicate with at least 4 constellation devices at once. The system makes it possible to calculate the position — in terms of spatial coordinates — of the object points “touched” by the probe. Acquired data are then available for different types of elaboration (determination of distances, curves or surfaces of measured objects). During the system set-up, the constellation Crickets (beacons) are manually placed in the working volume (we define this operation as “positioning”). After that, their coordinates are determined as much precisely as possible (this operation is said “location”). The positioning of constellation devices is one of the most critical aspects in the system set-up. In principle, Crickets can be arranged without restrictions all around the measured object. However, the number and position of network devices are strongly related to the dimensions and shape of both the measuring volume and the measured object. The accuracy in the location of constellation devices is fundamental for the accuracy of the coordinates of the touched points during measurement operation. It is important to assure a full coverage of the space served by network devices by a proper alignment of US transmitters. For that reason, an ad hoc software “pre-processor” has been developed in order to help the operator in positioning and locating constellation devices in the working volume, according to the measuring space and the measured object dimensional characteristics. The aim of the paper is to introduce and describe this computer-assisted approach. Some preliminary results of experimental tests carried out on the system prototype are also presented and discussed.
A Bond Graph Model for the Actuation Mechanism of Musculo-Skeletal Joints
Authors: Vaz Anand , Singh Kanwalpreet , Dauphin-Tanguy Genevieve
Published: July 2009

Modeling the dynamics of actuation of musculoskeletal joints involves the generalized three dimensional motion of rigid bones caused by flexible muscles which cling to the skeletal structures and is a difficult issue. A bond graph model for such joints is systematically developed. Muscles have been considered as string tube models. Each of the component subsystems such as bones, muscles, rotational couplings, etc. have been modeled as Word Bond Graph Objects. These are then integrated to yield the complete bond graph model. An example of a joint, with two mating bones and actuated by a pair of muscles is considered. The bond graph model for the joint system has also been verified using simulation. The resulting model is simple yet captures the complete dynamics and provides insight into the dynamics of musculoskeletal joint actuation.
Design With Free-Form Splines Over Irregular Meshes
Authors: Hahmann Stefanie , Bonneau Georges-Pierre , Barbier Se´bastien , Cornillac Me´lanie
Published: July 2009

Generating smooth surfaces of arbitrary topology is still a challenge. This paper considers the problem of creating a smooth parametric polynomial surface interpolating the vertices of an irregular triangular or quadrilateral mesh of arbitrary topological type. The surface is overall tangent plane continuous without any singular points and without any singular parameterizations. We particularly focus on design issues related to this spline model which offers several degrees of freedom. In particular, an exhaustive description of all available degrees of freedom is given and their geometric interpretation for shape design is specified. An extension of the model allows for additional normal vector interpolation and increases thus the number of design parameters. Finally several design issues are discussed and illustrated.
Orthopedics and Tribology
Authors: Segal David , Kandel Leonid
Published: July 2009

Mammalian joints, including human joints, are mostly synovial joints, which have low friction and are long lasting. With life expectancy on the rise, we are facing an increase in joint “wear and tear” resulting in cartilage damage. Biological repair has its limitations and when the articular cartilage is severely affected joint replacement is the solution. The longevity of artificial joints is also limited requiring new avenues of research to extend their durability and reduce the cost of repeated operations.
Multi-Material Freeform Fabrication of Active Systems
Authors: Malone Evan , Lipson Hod
Published: July 2009

Current Solid Freeform Fabrication (SFF) technologies can manufacture, directly from digital data, end-use mechanical parts in an increasingly wide variety of engineering materials. However, commercial SFF systems remain costly, complex, proprietary, and are limited to working with one or two proprietary materials during the course of building a part, hindering their broader application and the impact of the technology. The work we present here demonstrates (1) that SFF systems can employ many materials and multiple processes during the course of building a single object, (2) that such systems can produce complete, active, electromechanical devices, rather than only mechanical parts, and (3) that such multi-material SFF systems can be made accessible to, and are of interest to the general public. We have developed a research-oriented, multi-material SFF system and employed it to produce not only mechanical parts, but complete and functional Zn-air batteries, electrical wiring, flexible circuit boards, strain-gages, electromagnets, electroactive polymer actuators, organic-polymer transistors, and electromechanical relays. We have also developed and published the Fab@Home Model 1 open-source, multi-material, freeform fabrication system design. The Fab@Home project has received broad public and media attention, and more than 100 Model 1 machines have been built by individuals around the world.
Cortical Bone Periosteocytic Space Morphology Can Affect Osteocyte-Level Mass Flows and Shear Stresses
Authors: Golan S. , Elata D. , Dinnar U.
Published: July 2009

This work investigates the interstitial fluid flow through the osteocytic-lacunar-canalicular system of cortical bone. The study assumes that it is a dynamic environment that undergoes continuous morphological changes. The model employed is a typical canaliculus (an annular region filled with a gel-like matrix that has a characteristic external diameter of 200 nm and a characteristic length of 35 μm which connects two bone cells — osteocytes). Two canalicular morphological changes are investigated — local constrictions and permeability alterations. The continuity and Brinkman equations are solved for this model, analytically and numerically. The results indicate that pericellular morphology modifications can significantly alter mass flows and shear stresses around osteocytes. Similar mechanisms, if present in vivo, may lead to changes in solute fluxes and in the loads applied to the cells and affect the manner in which osteocytes perceive their environment, react and result in bone adaptation processes. Furthermore, they may provide further explanation to the fundamental paradox that the strains applied to whole bone (tissue-level) in vivo are much smaller than the strains necessary to activate bone-cell signaling in cell cultures.
Extracting the Elastic Modulus of Compliant Materials Using a Novel Plate Bulge Testing Technique
Authors: Golan S. , Elata D. , Dinnar U.
Published: July 2009

The mechanical properties of compliant materials such as biological tissues and biocompatible soft polymers are essential in medical research and engineering applications. These properties are often determined using techniques that require costly instrumentation (e.g. pull test machines). Alternative and more accessible methods can significantly aid the characterization process. The bulge test determines a material elastic modulus by analyzing the pressure-deflection response of thin samples made of this material. The technique has been extensively employed in the characterization of metals and semiconductors (modulus ∼ 100 GPa). By employing plate rather than membrane mechanics, the present study extends bulge testing to characterize materials with a modulus that is five orders of magnitude lower (∼ 1 MPa). The novel method is demonstrated analytically using plate theory, numerically using finite element modeling and experimentally by successfully applying it to polydimethylsiloxane (modulus ∼ 1.33 MPa). The introduced technique does not require costly equipment, is simple to implement and presents an appealing alternative to current characterization approaches.
Influence of Clearances on the Positioning Error of the Discharge Mechanism Doors on a Rail Wagon
Authors: Mendoza Jesus A. , Otero Luis L.
Published: July 2009

Among other types of wagons, Ferrominera Orinoco Company uses 350 hopper type wagons for ore transportation. Each of these wagons has a mechanical linkage system, made up of nine mobile elements plus a frame to open and close two rotary discharge doors located at the bottom of the wagons. This paper presents the influence of clearances in the kinematic pairs of the operating mechanism for a tight sealing of the doors. For this purpose, a new mathematical model is developed to show how the positioning error of the doors — from its theoretical fully closed position — may be controlled via an adequate assignment of the clearances in the kinematic pairs. The results show that the positioning errors of each door due to clearances are independent from one another and may be obtained by modelling the kinematic cycle comprising each door as an equivalent five degree of freedom linkage as to obtain the maximum possible error of each door according to the combination of clearances in the kinematic pairs. This way, the most appropriate normalized fit may be assigned in order to limit a maximum positioning output error of each door.
On the Nonlinear Vibrations of Clamped Oval Shells
Authors: Ibrahim S. M. , Patel B. P. , Nath Y.
Published: July 2009

In the present study, the nonlinear dynamic response of clamped immovable oval cylindrical shells subjected to radial harmonic excitation in the spectral neighborhood of the free vibration frequency is investigated. The formulation is based on the first order shear deformation theory. Geometric nonlinearity is inducted in the formulation considering moderately large deformation effects employing the Sanders type kinematic relations. Governing equations are discretized in space and time domains, respectively, employing computationally efficient finite-strip method and Newmark time marching scheme. Resulting nonlinear algebraic equations are solved using Newton-Raphson iterative technique. A detailed parametric study is conducted to bring out the influence of ovality parameter on the nonlinear vibration characteristics of different modes of vibrations of isotropic and angle-ply oval shells. For isotropic oval shells, it is observed that moderately oval shells show softening type nonlinearity whereas shells of large ovality show hardening type nonlinearity. The response of oval shells with large ovality reveals different temporal variation near to the semi-major axis region compared to that in the semi-minor axis region.
Modeling of Boiling Liquid Expanding Vapor Explosion (BLEVE): Plane, Cylindrical and Spherical 1D Model
Authors: Pinhasi G. A. , Dahan Y. , Dayan A. , Ullmann A.
Published: July 2009

A 1D plane, cylindrical and spherical numerical model was developed for estimating the thermodynamic and the dynamic state of the boiling liquid during a boiling liquid expanding vapor explosion (BLEVE) event. The model predicts, simultaneously, the flow properties of the expanding two-phase flashing mixture and its surrounding air. The possible presence of a shock wave formed by the fluid expansion through the air is accounted for in the model. Model predictions of the shock wave strengths, in terms of TNT equivalence for the various coordinate systems, were compared against those obtained by simple energy models. As expected, the simple energy models over predicts the shock wave strength. However, the simple model which accounts for the expansion irreversibility, produces results which are closer to current model predictions. For the 1D plane case the model simulates a BLEVE scenario in a tunnel, whereas for the spherical case the more realistic BLEVE scenario in free space is being studied.
Dynamic Vibration Absorber Optimal Design With Emphasis on Complete Machine Dynamics Modelling
Authors: Diveyev Bohdan M. , Stotsko Zinovij A.
Published: July 2009

The main aim of this paper is improved dynamic vibration absorbers design with taking into account complex rotating machines dynamic The is considered for the complex vibroexitated constructions. Methods of decomposition and the numerical schemes synthesis are considered on the basis of new methods of modal methods. Development of of complicated machines and buildings in view of their interaction with system of dynamic vibration absorbers is under discussion.
An Automated Procedure for the Geometrical Characterization of Root Canals
Authors: Tani Giovanni , Orazi Leonardo , Cuccolini Gabriele
Published: July 2009

In this work an original system for the geometrical characterization of root canals for dental implants was developed and tested. The aim of this work is to determine the shape and the size of the posts that best fit a statistical population of root canals with a defined maximum amount of removed tissue. The task is performed by an accurate acquisition of the shape of a statistically significant batches of root impressions: the geometry are then processed to obtain the post geometry. The acquisition is carried out using a conoscopic laser scanning device mounted on a 4 axis controlled CNC measurement system. The shape of the root canals were measured for each type of tooth, obtaining an average 3-D computer design of the canal profiles. Several comparisons between the acquired geometry and the representative forms of commercial posts are finally presented.
Hybrid Liquid Desiccant/Vapour Compression Air-Conditioning Systems: A Critical Review
Authors: Christodoulaki Roza I. , Rogdakis Emmanuil D. , Koronaki Irene P.
Published: July 2009

Hybrid Liquid Desiccant Cooling / Vapour Compression Systems is an environmentally friendly technology used to condition the internal environment of buildings. In contrast to conventional vapor compression air conditioning systems, in which the electrical energy drives the cooling cycle, desiccant cooling is heat driven; therefore, hybrid LDC/VCS have the potential to utilise cleaner energy sources such as gas, hot water, waste heat or solar thermal energy. In hybrid LDC/VCS, the latent cooling load is handled by the desiccant dehumidifier, while the sensible is handled by a conventional VCS. Hybrid systems combining liquid desiccant cooling with Vapor Compression Systems, Vapor Absorption Systems and Solar Collectors use less electrical energy compared to conventional air-conditioning alone, while these savings rise as the latent load increases. Unlike other surveys on desiccant cooling, this review focuses on a detailed coverage of the hybrid LDC/VC systems. Commonly used liquid desiccants are compared towards their physical properties. Hybrid LDC/VCS employing various components and features are summarized, while different system configurations are schematically presented. Key factors for the hybrid system performance are the desiccant material, the design variables and the conduction of experiments prior to operation.
Product Modern Design Platform to Support Product Development in Distributed Resource Environment
Authors: Dai Xudong , Meng Xianghui , Zhinan Zhang , Xie Youbai
Published: July 2009

The manufacturers are competing against each other based on their development ability. A manufacturer who wants to do better than others must emphasize its ability of product development. The resources that product development relies on are more distributed than ever along with the varying of the global design environment. So more and more resources outside of enterprises are needed during the product design process. The platform supporting the product modern design under the circumstance of distributed resources will meet the requirement of the enterprise’s product design and development under such conditions. The platform will also simplify the implementation on the integral of the IT support system for design resources outside of enterprises. In this paper the characteristics and supporting technologies of product design platform, which supporting the distributed design resource circumstance and centering on the enterprise, are studied. The building method of the platform is presented and a prototype of the product design platform is developed. Three subsystems are included in the platform. They are the product requirements analysis system, the product design planning system and the knowledge management system. Many design tasks can be supported on the platform, such as product requirement analysis, concept design, detail design, experiment, and maintenance knowledge acquirement. The distributing, implementing, tracking and managing of product lifecycle tasks can also be supported on the platform. The distributed design resources could be sealed as application components to provide design services. Design work flow model and knowledge flow model are built and controlled through the FIPER software. The design knowledge is managed based on the ontology theory. The virtual prototype of a complex product can be built and run more easily with the design platform. The process of building a virtual prototype could be described simply as following. Firstly the distributed models are sealed as application components. Then the components are published in the FIPER environment. Finally, the virtual prototype is built in the form of design work flow model in which the distributed components are integrated. To simulate the coupling of multi-discipline behaviors in a complex product design, the coupling formula is proposed to express the relations of different discipline behaviors. Based on the coupling formula, the coupling simulation can be run on the platform. Finally, a lifecycle performance prototype of an internal combustion engine is developed through the platform to verify the platform’s functions.
Investigations of Thermal Deformations and Their Compensation in CTX 210 V3 Lathe Slide
Authors: Olszewski Jakub , Ptaszyn´ski Wojciech , Staniek Roman
Published: July 2009

The accuracy and the repeatability of tool positioning in relation to the work piece is one of the most important features in contemporary NC lathes. Precise lathes are particularly required in the automotive industry. The applied designs of the NC lathe slides do not always assure the required thermal stability of work piece dimensions. It has been observed that during the continuous work time of the one of the world’s famous lathes, the X and the Z axes have been significantly deformed by means of thermal influence. Diagnostic investigations concerning the positioning accuracy have been performed according to the ISO 230/3 standard [7]. While investigations, unpermitted values of thermal deformations in both slide axes, have been observed. The design of the slides has been analyzed and an attempt has been made to minimize the positioning errors that are influenced by thermal deformations. Particular attention has been paid to the errors of the X axis as they influence directly upon the accuracy of the work piece cross dimensions. A new method of deformation compensations for the X axis has been elaborated. The method is based on the elongation measuring of the ball screw applied in cross slides and then programmed compensation in the X axis control system. The practical effectiveness of the introduced compensation method has been confirmed and a five times increase of the machining accuracy has been obtained.
A Virtual Adaptive Biofeedback System for Neuromuscular Rehabilitation
Authors: Barzilay O. , Wolf A.
Published: July 2009

The purpose of this research is to enhance the methods used in biomechanical rehabilitation by combining virtual reality, motion capture and biofeedback instrumentation. During training the subject is wearing a head-mounted helmet, in which virtual tasks (i.e. motions) are displayed to him. During training, the patient is asked to follow target motions which are displayed to him and match his own movement to them. During training the patient kinematics and electromyograms (E.M.G.) signals are being tracked by Vicon Motion tracking system. We use an intelligent learning system to learn, on-line patient performance. For training, we use kinematics and electromyogram data provided by the Vicon motion system. Once trained, the system changes and adapts the tasked displayed to the subject for better patient-specific neuromuscular rehabilitation. Moreover, the system creates a more entertaining environment also resulting in a more efficient physiotherapy in adults and especially in pediatric. Besides physiotherapy, this system can be used in other applications, such as performance enhancement in sports training and as an educational tool in any application requiring precise movement and coordination.
Experimental Parametric Study of Droplet Rapid Boiling in Immiscible Liquid
Authors: Haustein Herman D. , Gany Alon , Elias Ezra
Published: July 2009

The process of rapid boiling of a two phase droplet rising in an immiscible liquid environment has been experimentally considered within a new range of superheats (normalized Jacob number, 0.2< Ja˜ <0.5). In the course of the research numerous water-column boiling experiments were conducted for liquid propane droplets in a water environment. Boiling was generally calm and very rapid, concluding within several milliseconds, due to high heat fluxes across the interface. This work deals with the effect of various initial conditions on this distinctive boiling process. The parameters considered, are: the host liquid temperature, background pressure, initial droplet size and the size of the vapor nucleus inside the droplet. Their separate and combined effects have been recognized, and a correction factor based on initial droplet and bubble size is proposed. Through the parametric study the limits of rapid boiling have been approximately defined — between explosive and slow “conduction” boiling. In all experiments considered mass boiling rate is given by a function of the normalized Jacob number Ja˜ and the correction factor, to good agreement. Furthermore, due to the special nature of this boiling process, by use of the proposed factor the rapid boiling curve may be predicted for a wide range of initial conditions, for liquid propane or similar hydrocarbons. This allows design of a rapid boiling curve for a required application. Suggested applications range from alternative marine propulsion, to rapid direct-contact heat exchange.
A Numerical Analysis of Plastic Deformation Induced Rail Corrugation
Authors: Wen Zefeng , Jin Xuesong , Jiang Yanyao
Published: July 2009

The effect of track irregularities on the initiation and evolution of rail corrugation due to cyclic plastic deformation is investigated through a numerical method. The track irregularities studied in the analysis include an isolated irregularity (such as rail joint, scratch, squat) and periodically varying running surface of the rail. In the numerical method, the Hertz contact theory, an elastic-plastic finite element model and a vertical dynamics model for the railway vehicle coupled with the track are considered. An advanced cyclic plasticity model is used for the deformation analysis. The combined influences of the plastic deformation and the vertical coupling dynamics of the car and the track are taken into account in the corrugation development. The residual stresses and strains below the trough and crest of corrugation are obtained. The numerical results indicate that: (1) when a vehicle runs on rails with an isolated irregularity the contact vibration between the wheel and rail occurs at a large amplitude, and rail corrugation due to plastic deformation can be easily initiated and developed; (2) the passing frequencies of the plastic deformation induced rail corrugation are the same as the natural frequencies of the track; (3) the corrugation caused by the isolated irregularity and the periodically varying rail profile has a tendency to move along the running direction and its evolution rate decays with an increase in the wheelset passage; and, (4) the residual stresses stabilize after a limited number of rolling passes, and the residual strains increase at a reduced rate with increasing wheelset passages.
Tribology of Coatings for Use in Oil-Less Swashplate Compressors
Authors: Solzak Timothy A. , Polycarpou Andreas A.
Published: July 2009

Increasing efficiency through the use of tighter tolerances and more extreme conditions is becoming more prevalent in current compressor design. In an effort to enable oil-less operation, greater protection is sought through the application of hard protective coatings. Unlubricated unidirectional experiments were performed with a pin-on-disk tribometer to simulate swashplate compressors. Experiments included 52100 crowned steel pins and coated aluminum A390-T6 disks. WC/C, WC/C + DLC and TiAlN + WC/C were applied while some aluminum disks also contained a CrN underlayer to increase load bearing capacity. In step-loading testing the best performance was attained with one type of the CrN + WC/C multi-layered coatings, exhibiting friction coefficients as low as 0.05 with scuffing loads ten times larger than uncoated experiments. Based on the research presented in this work, hard coatings have the potential to replace oil in future compressors.
Time-Varying Nonlinear Designs for Underactuated Attitude Control With Two Reaction Wheels
Authors: Han Congying , Pechev Alexandre N.
Published: July 2009

Reaction wheels are commonly employed for high precisision and agile pointing in spacecraft. In this paper, we consider the realization of three-axis stabilization with only two reaction wheels installed along two principle axes. In practise, the total angular momentum of the whole spacecraft periodically varies with time because of the existence of in-orbit disturbances. With regard to the time varying system, firstly, a time varying control law is presented for velocity dumping based on center manifold theory. Then a continuous nonlinear feedback controller with a periodic time varying term is also presented for the attitude. Numerical simulations are presented to illustrate the effectiveness of the designs.
CMM Measurement Uncertainty Reduction via Sampling Strategy Optimization
Authors: Moroni Giovanni , Petro` Stefano
Published: July 2009

Uncertainty is a key concept in any environment which involves measurements to ensure process quality: a trade-off has to be found between measurement costs, which increase as uncertainty lowers, and costs related to measurement errors. In mechanics, geometrical conformance is a common requirement. Two similar standards series deal with the problem of uncertainty in geometrical error estimate: ASME B89.7.3 and ISO 14253. Geometrical inspection is often performed by means of a “Coordinate Measuring Machine” (CMM). For a CMM, a trade off between measurement and errors costs may be found by optimizing the sampling strategy. In this work a cost function will be proposed as support for finding a trade-off between measurement uncertainty and costs. This function may be optimized by means of an heuristic algorithm. The method will involve repeated measurements of calibrated parts to evaluate uncertainty (like in ISO/TS 15330-3). A case study will be proposed.
Time-Varying Underactuated Attitude Control Design With Feedback Linearization Using Two Pairs of Gas Jet Actuators
Authors: Han Congying , Pechev Alexandre N.
Published: July 2009

Research has shown that rigid spacecraft with two controls cannot be stabilized by continuous state feedback. In this paper, aiming at asymmetric spacecraft with two pairs of gas jet actuators, we design smooth time-varying controllers for the underactuated system. These optimal controllers are developed by introducing an assistant state variable and using feedback linearization techniques. Through this approach, the states of the closed-loop systems can converge with exponential rates and this is validated by numerical simulations. Compared with existing control designs for underactuated attitude systems, this approach is much simpler and can be also scaled to other applications.
Evaluation and Similarity of Systematic Methods for the Conceptual Design of New Products
Authors: Ja¨nsch Judith , Weiss Menachem P.
Published: July 2009

In the past the design of a new product used to be performed by intuition and by expertise based on previous successes, and even better on previous failures. When designing a product, a young engineer was fully dependent on the guidance, inspection and help of his superior in the design office. Such guidance was essential for long periods. In the second half of the 20th century systematic design methods have been developed, with the aim that even a novice designer will be able to devise a novel good product. The methods were developed in two very different trends, one in the USSR by G. Altshuller, by the name of TRIZ — a Russian acronym for the Theory of Inventive Problem Solving — and the other in Germany, by a few contributors and is generally known as the Pahl and Beitz method. These two techniques are quite different in approach and in details and have been further developed in the recent years. The Pahl & Beitz method has been enhanced by the ICDM tools and TRIZ has been further developed into SIT, ASIT and USIT versions. In this study, a comparison of all the versions will be made and differences and similarities are highlighted. The methods started very different, but as the development advanced, now quite a few basics and details of both methods, are getting closer to each other. Both ways became quite popular, and attracted many followers. This study presents a comprehensive comparison of the two routes of methods in solving engineering problems.
Mass Transport Through Biocatalytic Membrane Reactors
Authors: Nagy Endre
Published: July 2009

A mathematical model and its solution were developed to calculate the mass transport through catalytic membrane layer by means of explicit, closed expressions even in the case of the nonlinear Michaelis-Menten reaction kinetics and/or of variable mass transport — diffusion coefficient, convective velocity — parameters. Some typical examples on the Thiele modulus, applying the Michaelis-Menten kinetics and its limiting cases, namely the first-order kinetic (KM≫cm) and zero-order kinetic (cm≫KM) are shown for the prediction of the concentration distribution and the mass transfer rates as a function of the reaction modulus, namely first-order- and the zero-order reactions. It was shown the significant differences of the results obtained by the three different reaction orders.
Ship Monitoring and Control by Multisensor Data Fusion
Authors: Tiano Antonio
Published: July 2009

This paper discusses the applicability of ship monitoring and control by multisensor data fusion After introducing some critical issues in the area of ship motion control, an analysis is presented concerning the choice of different architecture of ship monitoring and prediction systems. A simulation study is presented concerning the design of a multisensor data fusion system for improving estimate of ship position based on low-cost onboard hardware.
Guidance Law Based on Differential Games for High Order Input Constrained Missile and Target
Authors: Rusnak Ilan , Hexner Gyo¨rgy
Published: July 2009

The problem of derivation of guidance laws based on the differential games formalism for high order and acceleration constrained missile and target is formulated. The objective used is the minimaximization of the square of the miss and of the energy expenditure of the players. Explicit formula of the guidance law based on differential game formulation for unconstrained arbitrary order minimum or non-minimum phase is derived. For constrained players with this approach numerous cases emerge. For constrained players only implicit formulas of the GL are derivable. Each case has different structure of the implicit formulas. The cases that are treated-classified are created for different player’s transfer functions, i.e. missile or target autopilot transfer functions are minimum or non-minimum phase, respectively. Relatively tractable case is when the missile and the target are both minimum phase (or belong to a wider class of autopilot transfer functions with monotonous ramp response). For the case of constrained missile and target, implicit formula of the guidance law are derived and numerically solved. For minimum phase players one would guess, from results of one sided optimization, that the GL for constrained players would be obtained by limiting the acceleration commands derived as if there were not acceleration limits. It is shown that although this may be considered a practical-pragmatic solution it is strictly suboptimal.
Upper Limb Assessment of People With Multiple Sclerosis With the Use of a Haptic Nine-Hole Peg-Board Test
Authors: Xydas Evagoras G. , Louca Loucas S.
Published: July 2009

In this work, a nine-hole peg-board test (NHPT) arrangement is implemented in a Virtual Environment with the use of a Haptic Interface that has the form of a small robotic arm. The Haptic NHPT is used as a mean for investigating the validity of a quantitative metric, which is based on smoothness maximization, as a possible assessment parameter for three dimensional reaching tasks. More specifically this study refers to the assessment of people with multiple sclerosis. The basic metric is developed by combining a neurophysical concept, which suggests that the three dimensional trajectories are piecewise planar, with the minimum jerk model (MJM) which in turn maximizes the smoothness along a predefined path. A total number of sixteen persons participated in the study. From these, nine were healthy young adults and seven were people with MS of various ages and at different stages of disease progress. All participants performed the exercise three times, of which only the second and third were used in the analyses. The results showed that the employed procedure was successful for developing a motion analysis metric for the smoothness in three dimensional trajectories. Also, a clear and traceable difference in performance appeared between the two groups, by using the developed assessment metric.
Freeform Shape Reconstruction Using Parametric Regression Spline
Authors: Moroni Giovanni , Rasella Marco
Published: July 2009

In inspection or reverse engineering, free-form shapes are reconstructed from a large set of sampled points. Since point acquisition error is unavoidable, shape fitting should be based on a rigorous diagnostic phase. In this paper, a new parametrical form of regression spline is introduced. The method applies statistical regression analysis, with the error treated as a variable of the problem. Hence, during the reconstruction process we distinguish between the systematic behavior of the sampled points, which represents the part shape, and the hi-frequency behavior of noise. This distinction leads to realistic and efficient reconstruction of complex parts. Both the multi-valued and the closed curves and surfaces of smooth and non-homogeneous types are represented. This work presents the method and demonstrates its feasibility on freeform parts applied to a new parametrical form of regression spline.
Enabling an Internal Process Benchmark Using the Analysis of PDM-Data
Authors: Roelofsen Julia , Fuchs Stefan , Fuchs Daniel , Lindemann Udo
Published: July 2009

Today’s development-processes are mainly driven by three factors: time, quality and costs. High quality products need to be brought to the market in as little time as possible with competitive low costs. In addition to this, development processes need more flexibility and creativity in order to meet fast changing market requirements. With these factors competing, ways need to be found for an optimal process of developing products [1]. In this contribution the theoretical background of a tool that enables an internal process benchmark is introduced. This tool will be implemented at an international automotive supplier company in order to show potential for process improvement. The internal benchmark enables the identification of best practice processes that help to shorten time to market. The tool uses objective PDM-data to analyse processes instead of the often used interviews or observations, which are a more subjective source for process data. Main points of investigation in the analysis tool are CAD-drawings, change-requests, notify-and responsibility-lists. For example the time it takes from the generation of a drawing to its release for production is analysed; another example is the number of drawings generated per person. The analysis can be carried out concerning different locations, different customers or different departments and thus enables a company-wide benchmark of the workflow implemented in the PDM-system. All results are visualised by charts, which have to be interpreted in order to be used for the identification of best practice processes. To support the interpretation of the development-process-analysis and to draw conclusions for corrective or investigative actions, a portfolio is generated. This portfolio provides information about optimal values of the process performance figures and gives hints to why low or high values (e.g. in the number of drawings generated per department) can occur.
Dynamic Properties of Delaminated Braided Textile Composite Beams
Authors: Dauda Benjamin , Oyadiji S. Olutunde , Potluri Prasad
Published: July 2009

In this paper, vibration analysis of through-width single- and multi-delaminated cantilevered composite beams is carried out using Finite Element Analysis (FEA) approach. Different configurations of multiple delaminations are considered. The FEA results for single delaminations are validated via experimental testing. It is found that changes in the natural frequencies of delaminated cantilevered beams are related to the number, type and distributions of delaminations within a beam. Also, the natural frequency shifts due to single or multiple delaminations are influenced by the thickness-wise locations of the delaminations. As the delamination is moved from the outermost inter-laminar layer towards the mid-plane of the beam, the natural frequency decreases and reaches a minimum value when the delamination is located at the midplane. Single delaminations have a more significant effect on natural frequencies than multiple delaminations of the same overall dimension as the single delamination. Furthermore, it is found that there is a greater reduction in natural frequency when multiple delaminations are close together than when they are spread out. However, where the locations of multiple delaminations coincide with nodal or antinodal vibration points, the effect is significantly altered.
An Approach for an Automated and Market-Driven Optimisation of Product Ranges as Part of the Product Lifecycle Management (PLM) Framework
Authors: Schumann Christian-Andreas , Rutsch Andreas
Published: July 2009

From the perspective of systems theory, looking at a defined product range of a company, it is possible to describe the main influences as well as restrictions from the market on it. After figuring out, which of those variables are specific, measurable, attainable, realistic, and timely, there is the potential to create sensed values for a “market-driven optimization of product ranges”-feedback loop. The controller of the circuit affects the reference to become the optimal product range for the customer. Therefore a second model or subsystem is needed, which commits the optimum product range in respect to economic interests of the quoting company. Changes in market demands will have, under the restrictions of intra-corporate economic targets, direct effect on the product ranges. Prior achieving that interlinking between market and product, the controller and its functions need to be determined. Rules have to be developed and evaluated in relation to proper feedback on market demands. The whole system will be prototypical implemented based on an integrated enterprise information system, including Computer Aided Design (CAD), Product Data Management (PDM), Part Management (PM), Enterprise Resource Planning (ERP), and E-Commerce (EC) subsystems. The feedback loop stated, will be the core of the system in the PLM framework. The main impact of the loop will be on the product data model, especially its requirements to definition.
Deformation and Fracture of a Silicate Melt Around Tg: Implications to Dynamics of Volcanic Eruptions
Authors: Ichihara Mie , Rittel Daniel , Rubin M. B.
Published: July 2009

The mechanical properties of magma around the glass transition temperature have not been characterized yet, though this subject is considered to be important in dynamics of volcanic eruptions. In this paper, we present an experimental investigation of stress-strain relation of synthetic magma at various temperatures and strain rates. The material behaves as an elastic solid at low temperature and/or high strain rate, and as a viscous fluid at high temperature and/or low strain rate. In the transition, it reveals work-hardening response. Although the work-hardening nature has not been reported for noncrystalline magma, it is important in constructing a mathematical model to represent the flow-to-fracture transition of magma, namely the transition of eruptions from effusive to explosive styles.
Kalman Filtering Tools for Early Detection of Change in Random Processes
Authors: Sherman Peter J.
Published: July 2009

There are many areas of science and engineering that involve random processes that are subject to structural changes. Examples of such changes can be caused by a failed machine component, or the onset of an epileptic seizure, to name a few. The Kalman filter (KF) has been a valuable tool for change detection for many years. But only in recent years have advances in computer processing power and software allowed the elements of the KF to be explored in any real depth. Traditionally, the depth in KF research has been focused on settings that were mathematically tractable. In this work we investigate a number of fundamental elements of the KF in settings that are sufficiently realistic to preclude in-depth mathematical analysis. Instead, we rely upon simulations. Two of the most fundamental and important elements of the KF include the covariances of the state and measurement processes. The state process covariance is perhaps the most important single element in the KF setting. Setting it to a value that is too small results in lack of adaptability, but low variability. Setting it too high allows the KF to track more rapid changes, but with greater variability (hence, more false alarms). In this work we explore the performance of the KF in relation to detecting short time changes associated with a slowly time-varying first order autoregressive process [AR(1)]. Such processes are more common that one might think. For example, even if the continuous process is of a high order, if it is sampled fast enough it can be well-modeled by an AR(1) process. And due to major advances in high speed data collection systems, many processes are sampled at much higher rates than is necessary to satisfy sampling laws. Our contribution includes a collection of KF tools that, when used together, can quickly and reliably detect certain types of small changes. To demonstrate the potential of these tools, we apply them to early detection of the onset of an epileptic seizure. The goal is to detect the change early enough, so that action to mitigate it can be applied.
Friction Phenomena on Microscale in Technical Contacts With Rubber
Authors: Wangenheim Matthias , Kro¨ger Matthias
Published: July 2009

The focus of this work is the friction of reciprocating seals. In most cases the counter face of sealing contacts is metallic. The machining process of these parts results in an upper boundary of surface roughness wavelength in the range of micro meter. Usually a lubricant is used to reduce friction and wear and thus increase the lifetime. Different mechanisms contribute to the friction in these systems: Viscous friction resulting from the shear of the lubricant, hysteresis friction caused by internal damping when the rubber material is excited while sliding on the rough counterpart. Adhesion is considered as having no large influence due to the lubricant preventing to build up bondings. The lubricant can establish a boundary layer on the surface of the contact partners. The shear resistance of this film contributes to the friction. The investigations presented in this paper focus on the hysteresis friction in dependence on the surface topography, sliding velocity, temperature and load. Furthermore the effect of a lubricant is studied: The experimental identification of boundary lubrication is presented together with its influencing parameters.
Surface Active Phospholipids as Cartilage Lubricants
Authors: Schroeder Avi , Verberne Gabi , Merkher Yulia , Diminsky Dvorah , Maroudas Alice , Halperin Gregory , Nitzan Dorrit , Etsion Izhak , Barenholz Yechezkel , Sivan Sarit
Published: July 2009

Efficient lubrication and extremely low friction are essential for proper functioning of synovial joints. Various joint dysfunctions were described in direct association with increased friction or adhesive forces. Surface-active phospholipids (SAPLs) are well known to reduce friction in synovial joints. This study demonstrates, using a novel human-sourced cartilage-on-cartilage setup, the potential of multilamellar vesicles (MLV) composed of the SAPL dimyristoyl phosphatidylcholine (DMPC) to act as effective lubricants, reducing static and dynamic friction-coefficients to levels of healthy synovial joints. Furthermore, MLV composed of DMPC, in sizes ranging from 0.8 to ∼3.5 μm, were found to be more effective lubricants than histidine buffer, saline, or synovial fluid. The ability to test new cartilage lubricants, simulating, to a great extent, natural conditions, using the setup presented herein is discussed.