bluuebunny/crossref_metadata_2025 huggingface dataset:
On Some Tribological Effects of Graphite Nodules in Belt Grinding of SG Cast Iron: Finite Element Analysis and Experimental Verification
Authors: Ben Tkaya M. , El Mansori M. , Zahouani H.
Published: July 2009

In this paper a 2D micromechanical model with two phases of elasto-plastic graphite and elasto-plastic matrix was developed to simulate the abrasive wear behaviour of ductile iron. The matrix elastic modulus is degraded once the ultimate strength is reached. The graphite phase was found to be worn rapidly on surface and seriously deformed beneath the worn surface. A number of cracks initiated at the graphite-matrix boundaries were also found on the subsurface. The finite element results were then compared with experimental results. They showed that different wear mechanisms occurred as a function of the attack angle of a single grit and the applied load. Severe wear caused plastic flow and material removal occurred by microcutting and microploughin.
Dimensional Inspection Systems Based on Air Gauges
Authors: Rucki Miroslaw , Barisic Branimir , Jaskolska Zofia
Published: July 2009

In the paper, the short overview of the air gaging have been presented. The most common methods of the back-pressure measurement have been described. The problem of the pneumatic-electric conversion of the measurement signal has been pointed out. The system based on the air gauges integrated with piezoresistive pressure transducers have been presented. In those systems the results of measurement are achieved in digital form, they are processed and recorded. The appropriate software enables the analysis of parameters of the process, too. Some of the characteristics of the Pneutronik device have been investigated and presented.
Discrete Model Analysis of Optimal Columns
Authors: Ram Yitshak M. , Krishna Srinivas Gopal
Published: July 2009

Keller has determined in [2] the shape of the strongest hinged-hinged column. This was the stepping stone in the solution of the long standing Lagrange problem of finding the shape of the strongest column in the clamped-free configuration. We consider here the discrete link-spring model of column which is hinged on one side and spring supported on the other side that maximizes the buckling load. It is shown that for certain rigidity of the supporting spring the solution is not unique. For the other range of rigidity the shape of the strongest column is invariant of the spring constant.
The Theoretical Views on Innovation Systems and the Application in China
Authors: Zhao Xin-Li , Gao Wen-Fei
Published: July 2009

This paper firstly introduces the different views of innovation, including the basic functions, characteristics and models of the national/sub-national innovation systems. Then, a new output model, interactive model and the main evaluating indicators of an innovation system are brought forward. The main evaluating indicators are: Innovation System Performance reflecting the previous output of the innovation system, and Innovation System Capacity expecting the future performance by effectively attracting, configuring and using all elements or resources of the innovation system. Finally, the application of innovation system in China is introduced, which includes the national innovation system and the sub-national innovation systems in The Pan-Pearl River Delta Area, Yangtze River Delta Area and Bohai Sea Rim Area.
CMM Measurement Variability Analysis: A Comparison Between Two Metrological Laboratories Measuring Three Industrial Workpieces
Authors: Aggogeri Francesco , Barini Emanuele , Levi Raffaello
Published: July 2009

Quality may be defined as a set of requirements a system should satisfy in order to meet customer’s needs. Control of these requirements assures satisfaction of relevant standards, and consequently the performance levels of a manufacturing/transactional stream. In this context it is fundamental to define control procedures and reliable measurement systems adequate for adopting improvement action as soon as anomalies and dysfunctions are detected. This paper deals with a study of measurement variability occurring during practical exploitation of CMMs (Coordinate Measuring Machines). These measurement systems are designed to probe selected points of workpiece surface, and compare the relevant coordinates or derived quantities with specified values; capability and versatility of CMMs justify their widespread use in industry. Evaluation of CMM measurement variability is however often awkward owing to a number of factors, such as e.g. measurement task, environment, operator and measurement procedures. A round robin exercise involving two industrial laboratories was planned in order to address these issues. Three typical machine tool parts were circulated among participants, who were asked to measure linear dimensions as well as tolerances at specified locations, according to an agreed upon schedule. Results of measurements, performed by experienced CMM industrial users, were analyzed in order to bring out discrepancies, and suggest remedial actions in the light of information gathered. Several factors involving metrological as well as other aspects were observed to cause major discrepancies, yielding in turn information on where to look for potential sources of trouble. Conclusions were drawn in terms of operating procedure, leading to improved information on origin and components of variability.
Computer Modeling of the Properties of Carbon Nanotubes and Composite Materials
Authors: Bochkareva L. V. , Sanikovich D. M.
Published: July 2009

The paper is devoted to the modeling of thermal conductivity of carbon nanotubes, damping and elasticity of composite materials. In work the researches are carried out on the basis of the method of molecular dynamics and the finite elements method. The creation of the software with the help of CASE-tools is carried out.
Eigenvalue Sensitivity Assignment by the Receptance Method
Authors: Tehrani Maryam Ghandchi , Mottershead John E. , Ram Yitshak M.
Published: July 2009

In this paper the problem of eigenvalue assignment in active vibration control by the receptance method using single-input state feedback is considered. The poles of the system and their sensitivities are assigned using measured vibration data from the open-loop system in the form of receptances, there being no need to evaluate or to know the system matrices M, C, K. The perturbation method is applied to a characteristic equation resulting in expressions for the derivatives of the pole eigenvalues with respect to the control gains. These sensitivities are expressed as a linear combination of the feedback control gains. The control effort necessary to assign the poles may be reduced by increasing the sensitivity of the poles. In addition, the uncontrolled poles in the system may be rendered insensitive for stability robustness. It is demonstrated that chosen eigenvalues may be rendered insensitive to all the control gain terms by choice of the distribution vector b. Numerical examples are provided to demonstrate how the technique works.
A Novel Dynamic Friction Model Based on Asperity Creep
Authors: Goedecke Andreas , Mock Randolf
Published: July 2009

We present a novel approach for the simulation of dynamic friction in engineering systems, based on a new surface asperity model including creep effects. Our novel friction model aims at understanding the link between the microscopic origins of friction dynamics and the response of the engineering-level friction induced vibrations. The approach is based on the assumption that the time- and velocity-dependent friction coefficient is mainly caused by creep growth of surface asperity contacts (microscopic contact patches between two rough surfaces) as proposed by Kragelskii, Rabinowicz, Scholz and others. At the heart of our approach is a new asperity model that includes creep effects. Based on the pioneering work of Etsion et al., we conducted extensive FEM simulations to analyze the creep behavior of an elastic-perfectly plastic hemisphere in contact with a rigid flat. The new asperity model is used as a building block for a fractal model for the contact between rough surfaces. The model yields the time- and velocity-dependent macroscopic friction coefficient. We demonstrate the practical applicability of the new dynamic friction model in a simple block-on-conveyor test case to analyze friction induced vibrations.
An Investigation Into Effect of Train Curving on Wear and Contact Stresses of Wheel and Rail
Authors: Jin Xuesong , Guo Jun , Xiao Xinbiao , Wen Zefeng
Published: July 2009

Some important papers concerning the studies on rail wear and wheel/rail contact stresses are reviewed. The present paper utilizes a numerical method to analyze the effect of railway vehicle curving on the wear and contact stresses of wheel/rail. The numerical method considers a combination of Kalker’s non-Hertzian rolling contact theory, a material wear model and a vertical and lateral coupling dynamics model of a half vehicle and a curved track. The present analysis investigates the influence of the curving speed, the curved track super-elevation and the rail cant on the wear and the contact stresses. Through the detailed numerical analysis, it is found that the maximum contact stress depends greatly not only on the curving speed but also on the profiles of the wheel/rail. The curving speed increasing leads to increase the normal load of the wheel rolling over the high curved rail, but, decrease the normal contact stress level under the condition of the optimum match of wheel/rail profiles. The track super elevation increasing efficiently lowers the contact stresses and the wear at a constant curving speed. The rail cant has a great influence on the low rail wear of the curved track. Increasing the rail cant leads to the great growth of the low curved rail wear, the reduction in the high rail wear. The results are very useful in the maintenance of the track.
Analysis on Impact Loading at Rail Welds at High Speed
Authors: Xiao Guangwen , Xiao Xinbiao , Wen Zefeng , Jin Xuesong
Published: July 2009

When a railway vehicle passes through a track with different weld irregularities at high speed, the impact loading of the vehicle coupled with the track is investigated in detail using a coupled vehicle/track model. In this model, a half vehicle is considered and modeled as a multi-body system. In the track model, a Timoshenko beam resting on discrete sleepers is applied to model each rail. Each sleeper is modeled as a rigid body accounting for its vertical, lateral, roll motions. A moving sleeper support model is used to simulate the interaction of the vehicle and the track. The ballast bed is replaced with equivalent masses. The equivalent dampers and springs are used to replace the connections between the parts of the vehicle and track. In calculating the coupled vehicle and track dynamics, Hertzian contact theory and the creep force theory by Shen et al. are, respectively, used to calculate the normal forces and the creep forces between the wheels and the rails. The motion equations of the vehicle-track are solved by means of an explicit integration method. The weld rail irregularity is modeled by setting a local track vertical deviation at a rail weld joint, which is described with a simplified cosine function. In the numerical analysis the effect of the different wavelength, depth, the position of the welded joint in a sleeper span, and vehicle speed is taken into account. The numerical results obtained are greatly useful in the tolerance design of welded rail profile irregularity caused by damage and hand-grinding after rail welding.
Nanotribological Investigation of the Role of Proteoglycans in Biolubrication
Authors: Seror Jasmine , Kampf Nir , Maroudas Alice , Klein Jacob
Published: July 2009

Articular joints in human body are uniquely efficient lubrication systems. While the cartilage surfaces slide past each other under physiological working conditions (pressure of tens of atmospheres and shear rates up to 106 – 107 Hz), the friction coefficient (μ) achieves extremely low values (down to 0.001) never successfully reached by mechanical prosthetic devices. Friction studies on polymer brushes attached to surfaces have recently demonstrated (17) their ability to reduce friction between the rubbing surfaces to extremely low values by means of the hydrated ions and the charges on the polymer chains. We propose that the extremely efficient lubrication observed in living joints arises from the presence of a brush-like phase of charged macromolecules at the surface of the cartilage superficial zone: hydration layers which surround the charges on the cartilage macromolecules might provide a lubricating ball-bearing-like effect as demonstrated for the synthetic polyelectrolytes (17). In this work macromolecules of the cartilage superficial zone (aggrecans) are extracted from human femoral heads and purified using well developed biochemical techniques (20). The extracted molecules are then characterized with atomic force microscope (AFM). By means of a surface force balance (SFB) normal and shear interactions between mica surfaces coated with these molecules are examined focusing on the frictional forces between such surfaces at normal stresses similar to those in human joints.
Analysis of the Production Variability in Manufacturing Lines
Authors: Colledani M. , Matta A. , Tolio T.
Published: July 2009

Performance evaluation models are used by companies to design, adapt, manage and control their production systems. Most of the effort has been spent in literature toward the development of efficient methodologies to estimate the first moment performance measures of the system, such as the expected production rate, the buffer levels and the lead time. However, the variability of the production output may drastically impact on the capability of managing the system operations, causing the observed system performance to be highly different from what expected. This paper presents an efficient method to estimate the variance of the number of parts produced, in a given time period, by production lines composed of unreliable machines. The method is based on the exact solution for two-machine lines with one buffer, which is used to approximately calculate the output variance of a multi-stage line. The accuracy of the proposed method is assessed by comparing results with those provided by simulation and by other existing methods. Moreover, the developed approach is used to characterize the behavior of the variance in relation to the system parameters.
Metallic Stereolithography
Authors: Gaspar Jorge , Ba´rtolo Paulo Jorge
Published: July 2009

The rising of consumers’ demands and an ever increasing pressure of international markets imposed a deep change in the product development process to respond to an increasing product complexity and higher quality, as well to the need to promptly introduce products into the market. Stereolithography plays an important role on this new product development context. This technology produces models for thermosetting resins through a polymerisation process that transforms liquid resins into solid materials. In this work, a new route to produce metallic parts through stereolithography is explored. The curing analysis of hybrid reinforced polymeric systems, polymerised through radicalar or/and cationic mechanisms, is investigated. The rheological behaviour of these polymeric systems is also evaluated due to its importance for recoating. The influence of other processing and material characteristics like light intensity, initiator concentration, powder size of metallic powders, degree of dilution, etc. is also investigated.
Model-Eliciting Activities: A Research-Based Method for Inquiry Learning and Professional Development in the Engineering Classroom
Authors: Moore Tamara J.
Published: July 2009

Attracting students to engineering is a challenge. In addition, ABET requires that engineering graduates be able to work on multi-disciplinary teams and apply mathematics and science when solving engineering problems. One manner of integrating teamwork and engineering contexts in a first-year foundation engineering course is through the use of Model-Eliciting Activities (MEAs) — realistic, client-driven problems based on the models and modeling theoretical framework. A Model-Eliciting Activity (MEA) is a real-world client-driven problem. The solution of an MEA requires the use of one or more mathematical or engineering concepts that are unspecified by the problem — students must make new sense of their existing knowledge and understandings to formulate a generalizable mathematical model that can be used by the client to solve the given and similar problems. An MEA creates an environment in which skills beyond mathematical abilities are valued because the focus is not on the use of prescribed equations and algorithms but on the use of a broader spectrum of skills required for effective engineering problem-solving. Carefully constructed MEAs can begin to prepare students to communicate and work effectively in teams; to adopt and adapt conceptual tools; to construct, describe, and explain complex systems; and to cope with complex systems. MEAs provide a learning environment that is tailored to a more diverse population than typical engineering course experiences as they allow students with different backgrounds and values to emerge as talented, and that adapting these types of activities to engineering courses has the potential to go beyond “filling the gaps” to “opening doors” to women and underrepresented populations in engineering. Further, MEAs provide evidence of student development in regards to ABET standards. Through NSF-funded grants, multiple MEAs have been developed and implemented with a MSE-flavored nanotechnology theme. This paper will focus on the content, implementation, and student results of one of these MEAs.
Dynamic Modeling and Control of a Piezo-Electric Dual-Stage Tape Servo Actuator
Authors: Boettcher Uwe , Raeymaekers Bart , de Callafon Raymond A. , Talke Frank E.
Published: July 2009

We have implemented the design of a dual-stage actuator tape head for enhanced reduction of lateral tape motion (LTM) disturbance. Our design consists of a conventional voice coil motor (VCM) and a micro-actuator for coarse and fine positioning, respectively. The micro-actuator, which is mounted on the VCM, uses a piezo crystal and allows following LTM up to the kHz regime, while the VCM follows low frequency LTM. Using step response measurements and a realization algorithm, we have created a multi-input discrete-time model of the dual-stage actuator. Based on the model, we designed and implemented a dual-stage controller, using a dual-input single-output approach based on a PQ method. The dual-stage controller controls the position of both actuators and enables an increased track-following bandwidth along with a control signal that is smaller in magnitude than that for a conventional single-stage tape head.
Rotating Shafts Affected by Transverse Cracks: A Sensitivity Analysis
Authors: Bachschmid Nicolo` , Tanzi Ezio , Pennacchi Paolo
Published: July 2009

The dynamic behaviour of heavy, horizontal axis, rotating shaft-lines affected by transverse cracks can be analysed in the frequency domain by a quasi linear approach, using a simplified breathing crack model applied to a traditional finite element model of the shaft-line. This allows to perform a series of analyses with affordable efforts. The analysis of the modelling procedure allows to define an approximated approach for simulating the dynamical behaviour, which allows to predict the severity of the crack excited vibrations, combined to modal analysis. this answers to the old-age question on how deep a crack must be to be detected by means of vibration measurements. The model of a 320 MW turbo-generator group has been used to perform a numerical sensitivity analysis, in which the vibrations of the shaft-line, and more in detail the vibrations of the shafts in correspondence to the bearings, have been calculated for all possible positions of the crack along the shaftline and for two different values of the depth of the crack. The calculated results confirm the predicted behaviour.
Shape Processing and Reasoning for Multiple Product Views: Key Issues and Contributions to a General Framework
Authors: Le´on Jean-Claude , Ferrandes Rosalinda , Giannini Franca
Published: July 2009

The concept of product view and the corresponding required models is a basic constituent of a product development process. Integration across product views is addressed through an analysis of the key characteristics of current geometric modellers. Here, topological and geometric issues are identified and major shape modelling principles are studied. As a result, the core concepts of a framework for product view integration are proposed and justified. The notions of mixed shape representation and layered topological representation are briefly outlined as part of the proposed framework. Categories of operators enabling the required shape transformations are also shortly introduced as element of the proposed framework.
Determining Network Control Solution Designs for Manufacturing Systems
Authors: Moyne James , Tilbury Dawn
Published: July 2009

In addressing the need for manufacturing systems that are more reconfigurable and flexible, there is an ever-increasing focus on utilizing networks at all levels to support control, diagnostics and safety functionality. Issues of performance and cost must be addressed. Further, making an appropriate network choice often involves examining the application environment rather than just universally applying a set of heuristics. The result is that network decisions, such as protocol, medium, and partitioning, are often made with incomplete or inappropriately prioritized information, leading to sub-optimal solutions in terms of both cost and performance. Three perspectives of information are needed for effective decision-making in network control system (NCS) deployment, namely theoretical, experimental and analytical. Theoretical involves understanding network operation, identifying metrics for NCS performance in the application environment, and mathematically evaluating the solution candidates with respect to these metrics. Experimental requires collecting and evaluating experimental data on particular aspects of network operation that are important to the application environment. Analytical involves a weighted cost analysis of the tradeoffs involved in network decision making and incorporates the results of theoretical and experimental analysis. In combining these three information perspectives, a methodology for making NCS design decisions is provided that allows the user to appropriately incorporate the application environment. An application of this methodology to a reconfigurable factory testbed demonstrates its use and effectiveness.
Active Control of an Incompressible Axisymmetric Jet
Authors: Greenblatt D. , Singh Y. , Nayeri C. N. , Paschereit C. O. , Depuru Mohan N. K.
Published: July 2009

An experimental investigation was conducted to compare the active generation and management of streamwise vortices in an incompressible jet flow using different flow control methods. The lip of the jet was equipped with a small flap deflected away from the stream at an angle of 30°, that incorporated a flow control slot through which steady suction, oscillatory suction and zero mass-flux perturbations were introduced. Data acquired were compared on the basis of momentum addition to the jet, the generation of streamwise vorticity and the generation of turbulent stresses. All active control methods produced an increase in jet momentum, stronger streamwise vortices and higher turbulence levels than those produced by a simple tab. The increase in jet momentum, combined with the generation of strong streamwise vortices and elevated turbulence levels, indicates potential for improvements in propulsion efficiency, mixing and possibly jet noise reduction.
Modelling of Decision-Making Process Relating to Design for Maintainability of Complex Technical Items
Authors: Tarelko Wieslaw
Published: July 2009

This paper deals with modelling issues of the decision-making process relating to design for maintainability of complex technical items. Especially, we presented the formal notation of a decision-making system, its elements and functions, and general description as well. Moreover, some application examples of design for the maintainability of such complex technical items as the ship power plants are presented. For development of the decision-making system, we applied a concept of the Mestrovic’s general system. Based on this system, we have worked out the computer-aided system called Maintainability Design System for ship power plants.
Numerical Modeling of Composite Concrete Walls
Authors: Kochavi Eytan , Kivity Yosef , Anteby Ido , Sadot Oren , Ben-Dor Gabi
Published: July 2009

Dynamic tests of three reinforced concrete samples and six Dynablok samples were performed in the blast simulator facility at the University of California San-Diego (UCSD). The purpose of these tests was to evaluate the performance of a novel protective wall design. These tests were numerically simulated at the Protective Technologies Research and Development Center (PTR&DC) of the Ben-Gurion University (BGU) in Beer-Sheva, Israel. The simulations were carried out using two commercial hydro-codes: LS-Dyna and Dytran. The purpose of these simulations was to calibrate the parameters of the material models available in the above codes. Once calibrated, the simulation results showed good agreement with the test results for largely deflected yet moderately damaged specimens.
Determination of Full Set Elastic Constants for Composite Materials on Basis of Frequency Response Analysis, FEA, and GA
Authors: Soloviev Arcady , Bychkov Anton , Shevtsova Maria
Published: July 2009

The number of engineering problems includes the identification of anisotropic composite elastic constants determination. We developed an experimentally - analytical technique for identification of all elastic constants of orthotropic materials. The offered technique is substantially based on measurement of eigenfrequencies and semi quantitative analysis of natural vibration modes, instead of wave propagation speed and fields of vibrational displacement used by other acoustic methods. The developed method of the elastic composite and piezoelectric materials properties identification is implemented in linked MATLAB – Comsol Multiphysics combining the finite element analysis (FEA) of oscillations dynamics and minimization of some functional, which type is determined by particularity of a solved problem. These techniques complement the early designed by authors’ FEM-based methods for orthotropic composite static tests. The offered dynamic tests include an evaluation of specimen’s frequency response, determination of natural frequencies and vibration modes of specimens both in natural experiments and numerical finite element simulations. The identification process consists of several stages. In series of static tests are determined all allowable modules. Further a complete matrix of elastic constant is constructed, but some modules specified by approximated values (in particular, interlaminar shear modules). A series of dynamic tests executed in which the periodical excitation of samples and the frequency response is recorded by means of piezoelectric actuators and sensors. Then on basis of early defined (in static tests and with use of mix rule) modules of composite and experimentally founded eigenfrequencies by means of FEM the vibration natural modes are identified. By combination of FEM, genetic algorithm (GA) and Levenberg-Marquardt minimization method the specification of composite mechanical properties is evaluated. Application of developed technique to orthotropic composite used in aviation structures (polymeric composite spar of the helicopter main rotor blade) is explicitly illustrated. The obtained results have shown a good efficiency of proposed identification methods. We demonstrate that proposed approach provides best reliability and shows small dependence on metering equipment precision.
Determination of Vibrating Structure Patterns Using Acoustic Waves
Authors: Lewin P. A. , Berger W. A. , Vecchio C. J. , Schafer M. E.
Published: July 2009

The objective of this work was to develop an acoustic field based technique that would be capable of remote sensing and reproduction of vibrating structure patterns. Knowledge of vibrating pattern characteristics is of interest in many applications, including minimization of noise generation in different media and design and optimization of piezoelectric transducers used in diagnostic ultrasound imaging. The technique is based on the angular spectrum method of wave-field analysis, and is applicable to both continuous and wideband pulsed waves. It also allows the effects of acoustic parameters such as absorption, dispersion, refraction, and phase distortion to be accounted for. Examples of remotely reconstructed surface velocity distributions of complex acoustic radiators operating in the low MHz (1–3MHz) range of frequencies will be presented. The examined geometries include single focused and plane axi-symmetric sources and arrays similar to those employed in both diagnostic and therapeutic ultrasound applications. The initial results obtained demonstrate the applicability of the angular spectrum approach and its extension to the analysis of acoustic field propagation through nonlinear liquid media. The method holds particular promise for use as a tool in the design and optimization of acoustic radiators. The ultimate goal of this research is to develop the model useful in optimization of ultrasound transducer performance and providing information on the degradation of transducer performance due to propagation through complex nonlinear media such as biological tissue.
Impact of Metabolic Mass Transfer on Monotonic Growth of Micro-Organisms
Authors: Vadasz Peter , Vadasz Alisa S.
Published: July 2009

A proposed Neoclassical growth theory of micro-organisms is shown to apply in a much wider variety of cases, from micro-level organisms via animal and human cell growth and up to the macro-level populations encountered in ecology. Including the metabolic mass transfer effects, that are an essential ingredient of the Neoclassical Theory, allows for the recovery of substantial and distinct phenomena observed experimentally. The proposed theory identifies the mechanism controlling the Lag phase, a result that holds impressive future potential in diverse applications. Different theoretical results are presented and compared with experimental data to substantiate the claim that the model based on the Neoclassical Growth Theory is the only available model that produces results, which are consistent with all experimental evidence.
The Effect of Thermal Waves on Heat Transfer Enhancement in Nanofluid Suspensions
Authors: Vadasz Johnathan J.
Published: July 2009

The spectacular heat transfer enhancement revealed experimentally in nanofluids suspensions is being investigated theoretically at the macro-scale level aiming at explaining the possible mechanisms that lead to such impressive experimental results. In particular, the anticipation that thermal wave effects via hyperbolic heat conduction could have been the source of the excessively improved effective thermal conductivity of the suspension is shown to be impossible.
Systems Modeling for Virtual Enterprise Configuration
Authors: Fidler Branislav , Valcˇuha Sˇtefan , Gunisˇ Adria´n
Published: July 2009

Many factors associated with industrial growth, such as continual development of technology, market globalization and customization increasingly spur companies towards inter-enterprise cooperation. Efficient cooperation and closer customer interface supported by system integration throughout the whole product lifecycle is becoming very important. The concept of virtual organization appears to be a progressive form for industrial networks, mainly for small and medium sized enterprises. Up to now however there exists in practice no implementation which is in complete conformity with the principles of virtual organization The precondition for further advancement is an integrating infrastructure composed of proper supporting systems. The key issue of the research presented in the paper is how to set up an optimal consortium for any specific demand or product desired by customer. This evolves in a software system design and development to automate the process of configuration of the manufacturing system. The output system data should define main customer requirements for the product’s manufacturability, manufacturing costs and delivery times, plus the optimal manufacturing consortium structure. This kind of functionality has been analyzed with the purpose to determine the set of initial system requirements. A new way of modelling within the analyses is discussed, and results are presented in the form of UML diagrams. Decision procedures regarding the major influence of the product on the organization’s structure and the way of knowledge processing are based on a data sequence as follows: 1. Product, 2. Technological process, 3. Manufacturing system, 4. Virtual enterprise. Flexibility and reconfigurability at a higher level of abstraction is considered more than a detailed design. The list of requirements is necessary to maintain the construction of a collaborative web-environment which as provisionally entitled the VEConfig System.
Experimental and Theoretical Study of Binary Droplet Head-On Collisions in MEMS
Authors: Zhao Ya-Pu , Wang F. C. , Feng J. T.
Published: July 2009

The experimental and theoretical investigations into the head-on collision between a landing droplet with another one resting on the PDMS substrate were addressed in this talk. The colliding process of the two droplets was recorded with high-speed camera. Four different responses after collision were observed in our experiments: complete rebound, coalescence, partial rebound with conglutination, and coalescence accompanied by conglutination. The contact time between the two colliding droplets was found to be in the range of 10–20 milliseconds. For the complete bouncing case, Hertz contact model was applied to estimate the contact time of the binary head-on colliding droplets with both the droplets considered as elastic bodies. The estimated contact time was in good agreement with the experimental result.
Importance of Tribology in Engineering Design
Authors: Brostow Witold , Buchman Alisa , Buchman Eli , Datashvili Tea , Hagg Lobland Haley E. , Olea-Mejia Oscar
Published: July 2009

From economical point of view wear is of the most important aspects of viability of an industrial enterprise. Mobile components in structures undergo wear and need to be replaced. This is particularly important for polymer based materials (PBMs). New methods have to be developed for wear mitigation in PBMs. Several such methods are under investigation showing positive results: blending, application of magnetic fields, application of radiation, and creation of micro- and nano-composites such as metal filler in polymer matrix. Working in this area we have provided a definition of material brittleness since no quantitative definition has existed before. At the conference these and other developments in tribology of PBMs will be reported from the point of view of informed design of materials structures.
Multi-Objective Optimization of an Axial Compressor
Authors: Maleki Hoda
Published: July 2009

The axial compressor is one of the most challenging components in aero-engine system and design; because of that finding an optimum design for this component is very important and valuable in the field. In this study, the objective functions selected to apply optimization method are the stage efficiency which leads to minimum losses, the stall margin which allows a wide stable characteristics curve and the inlet stage specific area which is related to the weight of a stage. In any case, the weight reduction inevitably causes loss of efficiency, and the higher efficiency will lead to decrease of the surge margin. The selected design variables are mean diameter of the stage, flow coefficient, axial velocity ratio for rotor and stator, rotational speed of the shaft and the inlet flow angle. The formulated multi-objective problem is solved by using weighting method in which the multi-objective problem is converted into a single objective one. The unconstraint single objective problem is solved by using interior penalty function method with DFP (Davidson Fletcher Powell) method. A computer code has been developed and results are taken corresponding to different sets of the weightages.
An a Priori Study for the Modelling of Subgrid-Scale Phenomena in the Interaction Between a Liquid Sheet and a Decaying Turbulence
Authors: Trontin Pierre , Vincent Stephane , Estivalezes Jean-Luc , Caltagirone Jean-Paul
Published: July 2009

Large Eddy Simulation (LES) of one-phase flow is widely used for industrial applications. However, LES of two-phase interfacial flows, i.e. two-phase flows where an interface separates liquid and gas phases, still remains a challenging task. The main issue is development of subgrid-scale models well suited for two-phase interfacial flows. Explicit filtering of 3D Direct Numerical Simulations has been employed to evaluate the order of magnitude of subgrid contributions. Two-phase interfacial flow simulations are carried out with an incompressible flow solver coupled to a ghost-fluid level-set interface capturing method. The originality of this work is the filtering of jump conditions at the interface. Subgrid terms of jump conditions are shown to derive from the filtering of both the pressure gradient term and the viscous term. Conclusions are drawn on the relative importance of the different subgrid scale contributions. These conclusions will contribute to develop subgrid-scale models which take into account the interface-turbulence coupling when LES are performed.
Application of a Fiber Optic Probe to High Void Fraction Air/Water Flow
Authors: Pertzborn A. J. , Smith W. C.
Published: July 2009

Successful development of CFD models for droplet flows is aided by knowledge of the droplet size distribution in the flow, but current instrumentation for measuring droplet size is limited. In an attempt to improve the quality of data collected, fiber optic probe (FOP) technology was investigated. A spray nozzle injected water droplets into an air stream to create a high void fraction droplet flow. Measurements were acquired with the spray nozzle at two different locations upstream of the FOP position. Mean droplet velocity measurements were acquired using laser Doppler velocimetry (LDV) at the FOP position. The droplet size distribution at the probe location was determined by using both the FOP and LDV measurements. The initial results indicate that FOP technology can successfully measure the droplet size distribution in a high void fraction air/water flow and it should be further developed for this application.
Conformal Nanocomposite Spray Coatings on Micro-Patterned Surfaces for Superhydrophobicity
Authors: Steele Adam , Moran Stephen , Cannon Andrew , King William , Bayer Ilker , Loth Eric
Published: July 2009

A novel conformal coating process is presented to transform surfaces with micro-morphology into hierarchical superhydrophobic surfaces using one-step, wet chemical spray casting. The nanocomposite coating consists of zinc oxide nanoparticles and organomodified polydimethylsiloxane (PDMS), also known as organosilane quaternary nitrogen compound. The coating is applied to a micro-patterned PDMS substrate of cylindrical microposts to create a stable superhydrophobic state for water droplets. An explanation for the non-wetting performance of the conformal nanocomposite coatings compared to previous non-conformal surfaces is also proposed.
Numerical Effect of Airflow From a Lower Canopy (Bluff Body) Into an Upper Canopy in Steady and Turbulent Condition
Authors: Izadi Mohammad J.
Published: July 2009

In this paper, a 3-D flow field around two bluff bodies in an incompressible fluid is modeled [1]. Formations of these two bodies are top to top (One on the top of the other) with respect to the center of each other. The lower on has a constant cross sectional area with a vent of air at its apex and the upper one has a variable cross sectional area with no vent on it. The vertical distances between the bluff bodies, the cross sectional area, and also the vent ratio of bluff bodies are varied here. Vertical distances of these two bodies are varied form zero to half, equal, double and triple the radius of the body with a vent on it (lower body). Flow condition is considered 3D, steady, turbulent, and incompressible. The drag force on each body and also the pressure around the two bodies are calculated. From the numerical results, it can be seen that, the drag force is constant over the range of zero to twenty percent of the vent ratios and for higher vent ratios when the upper bluff body is smaller than the lower one the drag force decreased, and it increased when the upper bluff body is larger than the lower one.
Effects of Car Inclination on Air Flow and Aerothermal Behavior in the Underhood Compartment
Authors: Khaled Mahmoud , Harambat Fabien , Peerhossaini Hassan
Published: July 2009

The study presented here concerns the impact of car inclination on the temperatures in the vehicle underhood compartment. We report here underhood thermal measurements carried out on a vehicle in wind tunnel S4 of Saint-Cyr. The underhood is instrumented by 80 surface and air thermocouples. Measurements are carried out for three thermal functioning points: the engine in operation and the front wheels positioned on the test facility with power-absorption-controlled rollers. Three car inclinations are tested.
Vortex Flow Behind a Heaving Elastic Flat Plate
Authors: Fuchiwaki Masaki , Tanaka Kazuhiro
Published: July 2009

An unsteady flow in a low Reynolds number region attracts attention in recent years. Various experiments/numerical analyses have been conducted in wake flow fields of objects with unsteady motions in low Reynolds number regions have been studied and reported recently. The authors clarified vortical structures in a wake of a rigid airfoil (NACA0010) with pitching, heaving and an unsteady motion with these motions combined quantitatively. The purpose of this study is to evaluate quantitatively the vortex flow formed in the wake of a flat airfoil whose edge deforms elastically by a PIV measurement by giving a heaving motion to the flat plate in a low Reynolds number region. A clear thrust producing vortex street equivalent to the airfoil shape can be formed by giving elasticity to the latter part of a rigid flat airfoil. vortices forming the thrust producing vortex street is extremely large and their vorticity is equivalent to that of NACA0010. In the mainstream of a vortex street forming a propulsion power generating vortex street, the vortex interval in the vertical direction is comparatively large and an interference of the vortices rolling up from the pressure and suction sides is small therefore the accelerating flow induced by these vortices becomes as large as the mainstream. The dynamic thrust acting on the elastic flat plate is greater than that of NACA0010. Because vortices with high vorticity roll up and these vortices are aligned with a comparatively large vortex interval in the vertical direction therefore a large accelerating flow is induced in the wake.
Thermally Actuated Pumping of a Fluid With a Free Interface Using Surface Asymmetry
Authors: Jo Myeong Chan , Narayanan Vinod
Published: July 2009

An experimental study of thermally actuated pumping of a single-component fluid is presented in the context of thermal management of a heat source. The prominent feature of this pumping method is that the very heat that is to be removed from the heat source causes a net fluid motion. Surface tension is the dominant driving force for convection in this study. An asymmetry in this force is created by the use of a surface with repeated asymmetric triangular structures. Silicone oil was used as the working fluid. Independent parameters that were varied consisted of the channel surface-to-ambient temperature difference and the fluid thickness. A dye-tracking imaging method was developed to determine the fluid interfacial velocity. The flow results were corroborated with interfacial temperature measurements obtained using infrared thermography. Dye tracking experiments indicate that the direction of net fluid motion is from the less-steep side of the ratchet towards its steeper side, resulting in a clockwise flow direction in the closed loop channel for all three liquid depths of 0.5 mm, 1.0 mm and 2.7 mm. The range of the net flow velocities varies from 0.18 mm/min to 0.86 mm/min. A fluid height of 1 mm results in a maximum net fluid velocity at both surface-to-ambient temperatures studied. Interfacial temperature contour maps indicate the presence of thermal structures that are indicative of convection cells, and that an optimum thickness exists for maximum heat transfer coefficient. Difference in streamwise gradients of temperature (and hence surface tension) on either side of the thermal structures causes a net streamwise surface tension gradient in the direction of net fluid motion. An optimal fluid thickness for heat transfer as well as net interfacial fluid velocity is suggested by the results.
Rudder Gap Cavitation and Its Suppression Devices
Authors: Oh Jungkeun , Lee Changmin , Lee Hee Bum , Rhee Shin Hyung , Suh Jung-Chun , Kim Hyochul
Published: July 2009

Development of rudder gap flow blocking device for lift augmentation and cavitation suppression is presented. In order to verify the performance of this device, cavitation visualization and surface pressure measurements were carried out in a cavitation tunnel. Numerical simulations were conducted using a computational fluid dynamics code for more rigorous verification. The new rudder system is equipped with cam devices, which effectively close the gap between the horn/pintle and movable wing parts. The experimental and computational results show that the proposed rudder system is superior to the conventional rudder systems in terms of the lift augmentation and cavitation suppression.