bluuebunny/crossref_metadata_2025 huggingface dataset:
On Passive Non-Iterative Variable-Step Numerical Integration of Mechanical Systems for Haptic Rendering
Authors: Lee Dongjun , Huang Ke
Published: July 2009

This paper consists of three parts. First, with a slightly-different, yet, more physically-plausible, discrete supply-rate (i.e. power), we propose a non-iterative (i.e. fast) and variable-step numerical integration algorithm for (scalar) discrete-passive mechanical systems, consisting of constant mass and damper, and a certain class of nonlinear spring. In the second part, we propose a fast passive collision handling algorithm with a spring-damper type virtual wall, which, to detect exact time of contacts, requires at most three intermediate non-iterative computations within each integration-step. We then propose a way of how to passively connect this discrete-passive, non-iterative, and variable-step mechanical integrators (with passive collision handling) to a continuous haptic device.
Exploiting Inate Motor Dynamics for High Stiffness Haptic Display on Brushless DC Motors
Authors: Wilson Robert P. , Niemeyer Gu¨nter
Published: July 2009

The maximum stiffness that can be rendered by impedance-controlled haptic devices has traditionally been limited by quantization, discretization, and delay in the digital loop. Recent research has shown that performance can be improved by utilizing the natural inductive stiffness inherent in brushed DC motors. This study extends the concept of exploiting a motor’s dynamics to the three phase brushless DC (BLDC) motor. It is analytically shown that the inductances of a BLDC motor’s windings map to a high physical stiffness. This stiffness is made available at frequencies important to haptic interaction by cancelling the resistance in each winding with analog feedback, effectively slowing the motor’s electrical dynamics. Experimental verification is obtained by implementing the proposed spring drive in analog circuitry in combination with a digital position feedback loop. The final results support the analytic solution and compare the spring drive favorably with traditional current and voltage drives for haptic applications.
Perception of Prototypical Environments in Model-Mediated Teleoperation
Authors: Park June Gyu , Niemeyer Gu¨nter
Published: July 2009

In teleoperation, master and slave robots directly exchange position and force data to establish a connection between local and remote sites. Model-mediation interjects an environment model rendered to the user to create a sense of remote presence. The slave continually updates this model from actual interactions. Here we evaluate a dual-mode implementation, which classifies the environment into one of two models describing rigid contact or free motion. Performance is measured against various prototypical environments, observing master force outputs to motion inputs to evaluate user’s perception of the environment. We find performance to depend on system lag as well as model error, such that multiple-model systems fundamentally outperform traditional architectures.
Discrete-Time Phase Compensated Repetitive Control for Piezoactuators in Scanning Probe Microscopes
Authors: Arıdog˘an Ug˘ur , Shan Yingfeng , Leang Kam K.
Published: July 2009

This paper studies repetitive control (RC) with linear phase lead compensation to precisely track periodic trajectories in piezo-based scanning probe microscopes (SPMs). Quite often, the lateral scanning motion in SPMs during imaging or fabrication is periodic in time. Because of hysteresis and dynamic effects in the piezoactuator, the tracking error repeats from one scanning period to the next. Commercial SPMs typically employ PID feedback controllers to minimize the tracking error; however, the error repeats from one operating cycle to the next. Furthermore, the residual error can be excessively large, especially at high scan rates. A discrete-time repetitive controller was designed, analyzed, and implemented on an experimental SPM. The design of the RC incorporates two phase lead compensators to provide stability and to minimize the steady-state tracking error. Associated with the lead compensators are two parameters that can be adjusted to control the performance of the repetitive controller. Experimental tracking results are presented that compare the performance of PID, standard RC, and the modified RC with phase lead compensation. The results show that the modified RC reduces the steady-state tracking error to less than 2% at 25 Hz scan rate, an over 80% improvement compared to PID control.
Piezo Polymer Films for Enhanced Acoustic Transmission Loss and Absorption
Authors: Whitmer Christopher E. , Kelkar Atul G.
Published: July 2009

The subject of this paper deals with the construction, characterization, modeling, and control of sensors and actuators made from piezoelectric polymers. The objective of this control was to improve the transmission loss and absorption characteristics of passive noise control materials by the addition of actively controlled component and to do so without a prohibitive cost. A brief background of piezoelectric materials and the practical considerations when using them is presented. The construction of piezo sensors and actuators from PVdF film is described, as is the development of cost effective driver, amplifier, and filter electronics for the system. In addition, the construction of an impedance tube testing apparatus is described. Then, the system is identified and control design models constructed. Next, the resonant controller structure utilized in preliminary experiments is presented. Finally, the experimental setup, investigation, and results of these actively controlled piezo samples are presented. Preliminary results show that collections of these resonant controllers are able to lead to significant (greater than 10dB on 30–50Hz bands) reductions. This would be a very effective method for tonal noise mitigation below 1500 Hz. Also presented are future improvements of the material sensing and new directions of research that are now in the experimental phase.
An Integrated Approach to Piezo Actuators Positioning in High-Speed AFM Imaging
Authors: Yan Yan , Zou Qingze , Su Chanmin
Published: July 2009

In this paper, an integrated approach to achieve atomic force microscope (AFM) imaging of large-size samples at high-speed is proposed, which combines the enhanced inversion-based iterative control (EIIC) technique to drive the piezotube actuator control for lateral x–y axes positioning with the use of a newly-developed dual-stage piezo actuator for vertical z-axis positioning. High-speed, large-size AFM imaging is challenging because large positioning error of the AFM probe relative to the sample can be generated due to the adverse effects—the nonlinear hysteresis and the linear vibration dynamics of the piezotube actuator. In addition, vertical precision positioning of the AFM probe is even more challenging because the desired trajectory is unknown in general, and the probe positioning is also affected by and sensitive to the probe-sample interaction. The main contribution of this article is the development of an integrated approach that combines advanced control algorithm with an advanced hardware platform. The proposed approach is demonstrated in experiments by imaging a large-size (50 μm) calibration sample at high-speed (50 Hz scan rate).
Self-Propulsion of a Free Planar Hydrofoil With Localized Vortex Shedding: Modeling and Model Reduction for Control
Authors: Kelly Scott David , Xiong Hailong
Published: July 2009

We describe a model for the planar locomotion of a free deformable hydrofoil in an infinite fluid. The time-varying shape of the foil is obtained as the image of a circle in the complex plane under a time-varying conformal transformation. The fluid is assumed to be incompressible and inviscid, but a mechanism is introduced whereby the foil can shed discrete vorticity from its trailing edge in accordance with a periodically enforced Kutta condition. Vortex shedding provides a propulsive force as a consequence of the conservation of impulse in the system; we compare the influence of this force on the model to forces arising in true inviscid locomotion. Simulations based on this model qualitatively reproduce the planar dynamics of swimming marine animals. We demonstrate that the model possesses an explicit Hamiltonian structure in between vortex shedding events, examine the energetics of certain motion primitives, and discuss an approach to model reduction through the assumption of a simplified wake.
An Irreversible Thermodynamic Theory of Friction and Wear
Authors: Dai Zhendong
Published: July 2009

Friction and wear are typical irreversible processes. Friction irreversibly degrades and dissipates high quality energy and wear irreversibly removes materials from the load-carrying surface. The two irreversible processes can be presented by entropy production, which is a non-negative quantity based on irreversible thermodynamics and thus serves as a basis for the systematic description of irreversible processes occurring in tribological system. In this paper, a thermodynamic framework has been presented for the mechanisms of friction and wear of continuum materials, where entropy production is used as the sole measure of energy dissipation and material damage evolution in the system. As a result, there is no need for physically meaningless empirical parameters to define the phenomenological frictional and wear parameters to trace tribological evolution in a friction and wear system. To validate the model, predictions are compared with experimental results, which indicate that entropy production can be used as a friction and wear evolution metric. The theory is founded on the basic premise that a solid continuum obeys the first and second laws of thermodynamics.
Enhanced Coherency of Thermal Emission From SiC by Coupled Resonant Cavity Structure
Authors: Dahan Nir , Niv Avi , Gorodetski Yuri , Kleiner Vladimir , Hasman Erez
Published: July 2009

Surface waves have been shown to play a key role in spontaneous thermal emission in the near-field as well as the coherence and the polarization properties of the nonradiative field. The near-field coherence of the delocalized nonradiative surface waves can be transferred into radiative fields by introducing a shallow grating on the surface. We show that the coherency of the thermal radiation can be enhanced by an order of magnitude compared with the coherency imposed by the delocalized surface waves. The enhanced coherency is due to coherent coupling between resonant cavities obtained by surface standing waves, where each cavity supports localized field that is attributed to coupled surface waves. We realized coupled resonant cavity structure on amorphous SiO2 and crystalline SiC, both support surface phonon-polaritons, to demonstrate extraordinary coherent thermal emission with a high quality factor of 600 and a spatial coherence length of 760λ.
Multi-Scale Finite-Element Analysis as a Base for a 3D Computerized Virtual Biopsy System
Authors: Podshivalov Lev , Fischer Anath , Bar-Yoseph Pinhas Z.
Published: July 2009

This paper proposes a novel multi-scale approach for three-dimensional non-invasive analysis of 3d bone models reconstructed from μCT/μMRI images. The feasibility of the proposed method is demonstrated on 2D models representing a simple 2D trabecular bone tissue structure. First, a fundamental domain decomposition method is applied to solve these models. Then, a numerical zoom technique is utilized for local solution enhancement. The proposed new multi-scale FE method has the potential to provide new insights into bone structure and behavior as a component of a computerized virtual biopsy system.
The Conquest of the Inner Space: Design and Analysis of Offshore Structures
Authors: Clauss Gu¨nther F.
Published: July 2009

Spectacular missions to the moon, the Mars and to other planets of our solar system has boosted public attention to the outer space for the last five decades. During the same period mankind has also conquered the inner space — with fantastic innovations and fabulous inventions — however, hidden under the sea surface, and hence widely unnoticed. While searching for new promising oil and gas fields the offshore industry operates in water depths that have never been explored before. Production systems already reach down to 2000 m, and will probably conquer greater water depths during the next years. Extreme environmental conditions in addition to these enormous water depths call for special solutions. This paper deals with recent developments of offshore deepwater production technology, e.g. SPARs, TLPs, Compliant Towers and huge mono-buoys. After a short survey of the development in ocean engineering from the first shallow water platforms in the Gulf of Mexico in 1947 to today’s deepwater production systems off the Brasilian coast the paper summarizes the principles of platform dynamics in waves to illustrate the advantages of specific design characteristics.
Development of Starin Gauges Using Electrically Active Textiles With Knitting Technology for Medical Applications
Authors: Soleimani Manuchehr
Published: July 2009

Current generation of textiles, including technical textiles are passive. However, the next generation of textiles will have the ability to monitor its environment and interact accordingly in order to accomplish a pre-programmed functionality. One of the solutions for incorporating the above components into a textile structure is to create electrically active zones within the structure, whose electrical characteristics could vary due to an environmental change or whose structural properties could be changed by the application of an electrical signal, for example change of dimensions due to the flow of an electrical current in the electrically active area. Generally textiles are made out of materials of very high electrical resistance and therefore these structures can be considered as materials with good electrical insulating properties. In this paper we are presenting application of electrically active textiles for strain gauge application. Electromechanical tests shows the chractersitics of electronic textile for strain gauge application.
Optimal Stresses and Load Capacity for Structures
Authors: Segev R. , Falach L. , deBotton G.
Published: July 2009

For a statically indeterminate structure we examine the class of internal forces that are in equilibrium with a given external loading f. We define the optimal stress φopt as the smallest possible magnitude of any equilibrating internal force distribution. The stress sensitivity k = maxf{φfopt/‖f‖}, a purely geometric property of structure, is a measure of the sensitivity of the structure to variable external loading. Using the result for optimal stresses, an expression for the stress sensitivity factor is obtained in terms of the structure’s kinematic interpolation mapping. These notions, the corresponding theoretical results, and a simple implementation to finite element models are presented using linear and conic programming.
Reconfigurable Machines
Authors: Katz Reuven , Koren Yoram
Published: July 2009

Reconfigurable Machines form a new class of machines that are designed around a specific part family of products and allow rapid change in their structure. They are designed to allow changes in production requirements by changes in the machine mechanical configuration and structure. Reconfigurable machines might be designed for various types of production operations such as machining, inspection and assembly. This paper introduces characteristics and design principles of reconfigurable machines, and describes their features using an example of our new full-scale industrial prototype of a Reconfigurable Bore Surface Inspection Machine (RBSIM). In addition, the paper also describes briefly other three prototypes of Reconfigurable Machines that were developed during recent years in our center: (1) the Reconfigurable Machine Tool (RMT), (2) the Reconfigurable Inspection Machine (RIM), and (3) the Reconfigurable Assembly Machine (RAM).
Motion Planning of an Innovative Serial Robot for Energy Consumption Reduction With “On Fly” Pieces Grasping
Authors: Menegolo Andrea , Bussola Roberto , Tosi Diego
Published: July 2009

The following study deals with the on-line motion planning of an innovative SCARA like robot with unlimited joint rotations. The application field is the robotic interception of moving objects randomly distributed on a conveyor and detected by a vision system. A motion planning algorithm was developed in order to achieve a satisfactory cycle time and energy consumption. The algorithm is based on the evaluation of the inertial actions arisen in the robot structure during the pick and place motions and it aims to keep constant the rotation velocity of the first joint during the motion, the grasping and the discarding phases. Since the algorithm must be applied run time and the number of the reachable pieces can be high, a particular care was dedicated to the computational burden reduction. Subsequently to an analytic study of the kinematical constraints and the criteria definition for the choice of which piece to grasp, a devoted simulation software was developed. The software allows the control and the evaluation of the effects of all the main parameters on the system behavior and a comparison of the cycle time and the energy consumption between the proposed algorithm and a standard point-to-point motion strategy.
Software Tools to Support Advanced Design Techniques and Processes
Authors: Campbell Michael M.
Published: July 2009

Collaboration between engineering and manufacturing can significantly reduce product costs, and increase product quality. The definition, capture and re-use of standard design features, with their associated proven manufacturing processes in the design stage can significantly reduce manufacturing cost and time to market. Today, 3D models are becoming the central repository for more and more of the critical information which is necessary throughout the Product Development Process. Significant process improvements are possible when organizations embrace the idea of a model-centric design approach, where not only geometry and attributes are captured in the 3D CAD model, but also other data relevant downstream data such as GD&T, 3D annotations, and now even manufacturing process information. The strategies for actually machining and producing designs are important assets for companies. Now, existing manufacturing process knowledge can be capture by the manufacturing engineer using XML based template, and through the use of new CAD technology, this knowledge can be attach to design features. The design feature geometry and attributes (along with the embedded process knowledge) can then be made available to the broader organization, through catalogs of company standard design features such as holes, pocket, step, groove, flange, .. etc. During the engineering activities, as the design model evolves, the design engineer is able to re-use these standard features, creating a 3D model that not only includes the geometric definition of the product, but also the validated, proven process by which that geometry can best be produced. Downstream, once the design is handed off to manufacturing, the manufacturing or process engineer has access to tools that will allow him to extract the process information from the 3D model and define rules to automate the creation of the machining process plan for this model. Specific fixtures required for the different steps of the process can be easily developed using the in-process 3D model, which is generated automatically based on stock removal. Multiple scenarios, based on varying machining resources, production quantity and cycle time, can be analyzed, allowing the process engineer to develop and optimized process plan. This model-centric approach, which leverages product and process data re-use, improves product quality and reduces manufacturing process planning and production time. Typical savings are realized in tool design, increased production throughput and savings due to improved process quality from using validated processes prior to production.
Assembly System Reconfiguration Planning Using Genetic Algorithm
Authors: Bryan A. , Hu S. J. , Koren Y.
Published: July 2009

Due to increased competition, the rate at which manufacturers introduce new product families to the market is increasing. However, the cost of changing manufacturing facilities to produce new product families can outweigh the benefits obtained from increased revenue. Reconfigurable Manufacturing Systems (RMSs) have been proposed as a cost effective strategy for manufacturing product families. Although methods for measuring RMS scalability and convertibility exist, there is a lack of methods for obtaining reconfiguration plans for assembly systems. This paper introduces assembly system reconfiguration planning (ASRP) as method to obtain reconfiguration plans for assembly systems. A genetic algorithm is developed for solving the ASRP problem.
Mass Detection With Nonlinear Nanomechanical Resonators
Authors: Buks Eyal
Published: July 2009

Nanomechanical resonators having small mass, high resonance frequency and low damping rate are widely employed as mass detectors. We study the performance of such a detector when the resonator is driven into a region of nonlinear oscillations [1]. We predict theoretically that the mass sensitivity of the device in this region may exceed the upper bound imposed by thermo-mechanical noise upon the sensitivity when operating in the linear region. On the other hand, we find that the high mass sensitivity is accompanied by a slow response of the system to a change in the mass. For experimental demonstration we employ homodyne detection (see Fig. 1) for readout of the output signal of an optical displacement detector, which monitors the motion of a doubly clamped nanomechanical resonator made of Pd-Au [2, 3]. The nanomechanical resonator is driven into the region of nonlinear oscillations (see Fig. 2) and the region of bistability is identified (see Fig. 3). As expected theoretically [1] we find that when operating close to the edge of the bistability region the device exhibits strong intermodulation amplification [2] (see Fig. 3). Moreover, strong noise squeezing in the output signal of the homodyne detector is observed in this region [3] (see Fig. 4). An alternative mass detection scheme, in which the resonator is driven into a stochastic resonance, will also be discussed [4].
Tribological Challenges in Small Devices
Authors: Williams John A.
Published: July 2009

Micro-System Technology, which encompasses micro-electro-mechanical systems or MEMS, is a rapidly growing interdisciplinary technology dealing with the design and manufacture of miniaturised machines with major dimensions at the scale of tens, to perhaps hundreds, of microns. Because they depend on the cube of a representative dimension, component masses and inertias rapidly become small as size decreases whereas surface and tribological effects, which often depend on area, become increasingly important. Although our explanations of macroscopic tribological phenomena often involve individual events occurring at the micro-scale, when the overall component or device size is itself miniaturised it may be necessary to re-evaluate some conventional tribological solutions. While absolute loads are small in such micro-devices, tribological requirements, especially in terms of device longevity, which may be limited by wear rather than friction, are demanding and will need imaginative and novel solutions. Not only is the available material set limited by the fabrication process but, in addition, the resulting components which have small linear dimensions are not, by conventional standards, of high precision and this too can impact on their tribological behaviour.
Application of the Complex Envelope Vectorization to a Boundary Element Formulation
Authors: Giannini Oliviero , Sestieri Aldo
Published: July 2009

The complex envelope vectorization (CEV) is a recent method that has been successfully applied to structural and internal acoustic problems. Unlike other methods proposed in the last two decades to solve high frequency problems, CEV is not an energy method, although it shares with all the other techniques a variable transformation of the field variable. By such transformation involving a Hilbert transform, CEV allows the representation of a fast oscillating signal through a set of low oscillating signals. Thanks to such transformation it is possible to solve a high frequency dynamic problem at a computational cost that is lower than that required by finite elements. In fact, by using finite elements, a high frequency problem usually implies large matrices. On the contrary the CEV formulation is obtained by solving a set of linear problems of highly reduced dimensions. Although it was proved that CEV is in general a successful procedure, it was shown that it is particularly appropriate when the modes of the system have a negligible role on the solution. Moreover, the numerical advantage of the CEV formulation is much more pronounced when full matrices are used. Thus, for the first time it is applied to a boundary element formulation (BEM). Both external and internal acoustic fields of increasing complexity are considered: the internal and external field generated by a pulsating sphere; the external field of a forced box, where the velocity field is determined by finite elements; a set of 4 plates that form an open cavity. The results are compared with those obtained by a BEM procedure (SYSNOISE), highlighting the good quality of the proposed approach. An estimate of the computational advantage is also provided. Finally it is worthwhile to point out that the reduction of the BE matrices allows for an in-core solution even for large problems.
On the Dynamic Contact Problem for a von Ka´rma´n Plate
Authors: Bock Igor , Jarusˇek Jirˇi´
Published: July 2009

The solvability of dynamic contact problems for von Ka´rma´n plates is proved. Elastic as well as viscoelastic short and long memory materials are considered.
Glucose Oxidation by Nano-Fibrous Anodes in a Fuel Cell
Authors: Schechner Pinchas , Bubis Eugenia , Faiger Hana , Zussman Eyal , Kroll Ehud
Published: July 2009

This work adds more experimental evidence regarding the feasibility of using glucose to fuel fuel-cells with anodes that have a high area-to-volume ratio. Electrospinning was used to fabricate sub-micrometer size fibrous electrocatalytic anode membranes for the oxidation of glucose in an alkaline fuel cell (AFC). The fibers of the membranes were made of polyacrylonitrile (PAN) and coated with silver by electroless plating. The anodes were tested while installed in a membranless fuel cell. The results presented include the open circuit voltage, OCV, the polarization curve, the power density as a function of the current density, and the peak power density, PPD. The measurements were performed with constant concentrations of glucose, 0.8 M, and KOH electrolyte solution, 1M. The performance of the anodes was found to improve as the diameter of the silver-plated fibers decreased. The highest PPD of 0.28 mW/cm2 was obtained with an anode made of plated fibers having a mean fiber diameter of 130 nanometers. We conclude from the results that saccharides in general, and glucose in particular, can serve as fuels for fuel cells, and that silver-plated polymeric electrospun electrodes have advantages due to their large surface area.
Ormat Rankine Cycle Configurations for Utilization of Low Temperature Heat Sources
Authors: Bronicki Lucien Y.
Published: July 2009

Concerns about the effect of CO2 emissions on climate change and rising energy costs have renewed the interest in efficiency improvement in fossil fuel use as well as the utilization of locally available low or moderate temperature heat sources, such as geothermal or solar. This paper summarizes twenty years of Ormat’s very significant achievements in developing cycles, configurations and equipment for electricity generation from low grade waste heat and water dominated geothermal resources. As of the end of 2007 some 30 plants ranging from 200 kW to 130 MW totaling about 1000 MW are in operation.
Thermal Simulation of an Arbitrary Residual Stress Field in a Fully or Partially Autofrettaged Thick-Walled Spherical Pressure Vessel
Authors: Perl M.
Published: July 2009

The equivalent thermal load was previously shown to be the only feasible method by which the residual stresses due to autofrettage and its redistribution, as a result of cracking, can be implemented in a finite element analysis, of a fully or partially autofrettaged thick-walled cylindrical pressure vessel. The present analysis involves developing a similar methodology for treating an autofrettaged thick-walled spherical pressure vessel. A general procedure for evaluating the equivalent temperature loading for simulating an arbitrary, analytical or numerical, spherosymmetric autofrettage residual stress field in a spherical pressure vessel is developed. Once presented, the algorithm is applied to two distinct cases. In the first case, an analytical expression for the equivalent thermal loading is obtained for the ideal autofrettage stress field in a spherical shell. In the second case, the algorithm is applied to the discrete numerical values of a realistic autofrettage residual stress field incorporating the Bauschinger effect. As a result, a discrete equivalent temperature field is obtained. Furthermore, a finite element analysis is performed for each of the above cases, applying the respective temperature field to the spherical vessel. The induced stress fields are evaluated for each case and then compared to the original stress. The finite element results prove that the proposed procedure yields equivalent temperature fields that in turn simulate very accurately the residual stress fields for both the ideal and the realistic autofrettage cases.
Flow Morphologies and Bubble Dynamics in Microchannels With Entrenched Micro-Pin Fins
Authors: Krishnamurthy Santosh , Peles Yoav
Published: July 2009

Flow boiling of HFE 7000 on micro pin fins entrenched inside microchannels was experimentally studied for G = 350 kg/m2s to G = 827 kg/m2s and wall heat fluxes from 10 W/cm2 to 110 W/cm2. Bubbly, multiple, and wavy-annular flow patterns were observed. The interaction of the bubble with the pin fins during nucleate boiling is detailed.
Thermo-Mechanical Aspects of Adiabatic Shear Failure of AM50 and Ti6Al4V Alloys
Authors: Rittel D. , Wang Z. G.
Published: July 2009

The thermo-mechanical aspects of adiabatic shear band (ASB) formation are studied for two commercial alloys: Mg AM50 and Ti6Al4V. Tests are carried out on shear compression specimens (SCS). The evolution of the temperature in the deforming gauge section is monitored in real time, using an array of high speed infrared detectors synchronized with a Kolsky apparatus (split Hopkinson pressure bar). The evolution of the gage temperature is found to comprise 3 basic stages, in agreement with Marchand and Duffy’s simultaneous observations of mechanical data and gauge deformation patterns (1988). The onset and full formation stages of ASB are identified by combining the collected thermal and mechanical data. Full development of the ASB is identified as the point at which the measured and calculated temperature curves intersect and diverge thereon. At that stage, the homogeneous strain assumption used in calculating the maximum temperature rise is no longer valid.
Modelling the Evolution of Packaging Systems for Product Variation
Authors: Matthews Jason , Singh Baljinder , Mullineux Glen , Medland Tony
Published: July 2009

Manufacturing practices such as mass customization mean producers are often making changes to their product and its respective packaging. Many of these changes arise over short periods due to marketing and customer demands. Some products are stable over long periods whilst others are short lived or seasonal. This paper presents an approach employing the capability of a constraint-based modelling environment to model and simulate variations in machine design configuration to cope with evolving product. The paper continues to explain the product effects, and how understanding product constraint relationships can offer the full understanding of the processing capability for the change product.
Twenty Years After the Production of the First Heavy Water Drop in Romania: July 17th, 1988 – July 17th, 2008—Piping Systems
Authors: Alessandrescu Aurel M.
Published: July 2009

1. Heavy Water application. 2. Heavy Water technology. 3. Isotope exchange installation- piping systems characterstics. 3.1. Piping systems characteristics: (a) crack-inducing corrosion in wet and gaseous hydrogen sulphide medium. (b) selection of a higher nominal pressure than the normal pressure for pipe classes. (c) minimization of flanged pipe joints. (d) provision of piping systems selfcompensation in case that lenticular pipe expansion loops can not be used. (e) use of spiral-wound gaskets for all the piping systems flanged connections. 3.2. Piping-equipment system interaction. 3.2.1. Severe limitation of the loads in the piping systems-equipments joints. 3.2.2. Use of constant elastic supports to protect the piping systems associated equipment nozzles. 3.3. Bearing range. 4. Today objectives: to extend the predicted service-life of the piping systems. 5. Nomenclature. 6. References.
Vibration Suppression of Flexible Structures Using the Infinite Dimensional Laplace Domain Approach
Authors: Sirota Lea , Peled Irit , Halevi Yoram
Published: July 2009

The problem of obtaining an explicit, exact response of a flexible system to initial distributed input in infinite dimensional modeling is considered. The paper proposes a method to present the response in terms of propagating waves that are reflected from boundaries with general conditions. The result is then examined under control with the absolute vibration suppression (AVS) controller, which was originally designed for a concentrated input. It is shown that the vibration suppression properties of this controller are extended to systems with distributed input.
Viscoplastic Constitutive Equation for Computer Simulation of Hot Working Processing
Authors: Moriwaki Ichiro , Nakamura Morimasa , Morimoto Kei , Iizuka Takashi , Saito Kenji
Published: July 2009

The newly developed viscoplastic mechanical model based upon the viscoplastic model of the Chaboche type is proposed. The points of proposition are (i). Dimensional ambiguity existing in the Chaboche type’s equation is extinguished. (ii) Dependence of yield stress on strain rate is made clear and installed into the model. Its validity is verified by simulating the torsional test data on the steel performed by C. Rossard and P. Blain at elevated temperature using the proposed model. Furthermore, the six viscoplastic material parameters contained in the model are identified by the simulation involving coefficient of viscosity.
Experimental Analysis of a Translator Based on a Wohlhart Mechanism
Authors: Dahan Marc , Racila Laurentiu
Published: July 2009

The aim of this paper is to present a theoretical and experimental analysis of 6R-translator based on Wohlhart 6R overconstrained mechanism. The variable distance between the fixed plane and the platform of the 6R-translator is obtained using a theoretical approach and then validated experimentally.
Nano-Porous Substrates Reduce Beetle Attachment Force
Authors: Gorb E. , Hosoda N. , Gorb S.
Published: July 2009

Traction experiments with the seven-spotted ladybird beetles Coccinella septempunctata (L.) (Coleoptera, Coccinellidae) were carried out to study the influence of surface structure on insect attachment. Force measurements were performed with tethered walking insects using a load cell force transducer. For each beetle, forces were measured on five different substrates: (1) smooth glass plate; (2) smooth solid Al2O3 (sapphire) disc; (3 – 5) porous Al2O3 discs (anodiscs, back side) with the same pore diameter (220 – 235 nm), but different porosity (28, 42 and 51%). Males (N = 10) and females (N = 10) were used in experiments (10 single runs on each surface). Additionally, inversion tests were performed after each traction force measurement. The force ranged from 0.368 to 10.370 mN in males and from 0.514 to 6.262 mN in females. In both sexes, the highest force values were obtained on the smooth glass and sapphire surfaces, where males generated considerably higher forces compared to females. On all three porous substrates, forces were significantly reduced in both males and females, and the only difference for surfaces was obtained between two extremes: anodiscs with the highest (51%) and lowest (28%) porosity. Males produced essentially lower forces than females on anodiscs samples. Experimental insects performed well and showed normal locomotion on both smooth surfaces. On all anodiscs samples, beetles usually were not able to get a grip and slid over the surface, refused to walk and came to a standstill or even turned over on their backs. When substrates were inverted to 90° and 180°, insects were still able to remain attached to both the glass and sapphire samples, but failed on anodiscs. The reduction of insect attachment on anodiscs surfaces is explained by (1) possible absorption of the secretory fluid from insect pads by porous media and (2) effect of surface roughness.
High-Resolution Neutron Diffraction Employing Bragg Diffraction Optics: A Tool for Advanced Nondestructive Testing of Materials
Authors: Mikula Pavol , Vra´na Miroslav , Mra´z Lubos , Karlsson Leif
Published: July 2009

The present paper deals with an efficient use of high-resolution neutron diffraction for material research studies, namely for studies of internal stresses. It is demonstrated that a conventional neutron diffractometer equipped with focusing elements can be used as neutron strain/stress scanner with medium power neutron sources. Principles of this enhanced technique are introduced and an example of internal strain/stress measurements in the vicinity of welds is presented.
Development of an Intelligent Rotating Machinery Diagnostics Programme
Authors: Suhacˇ Blazˇ , Vizˇintin Jozˇe , Bosˇkoski Pavle , Juricˇic´ Dani
Published: July 2009

Rotating machines are one of the most wide spread items of equimpnet in the industrial plants; hence the reliable operation is of great practical importance. Analyses show that when a run-to-failure philosophy is adopted in rotating machinery maintenance, their downtime is usually three to four times longer comparing to a periodic or proactive maintenance approach. A successful proactive maintenance program requires an integration of several diagnostic procedures into an intelligent data processing system. Such a system allows detection of a broad range of faults in an early stage. The main aim of this paper is to present current results of our development of an intelligent rotating machinery diagnostics program for detecting a broad range of faults from signals which can be measured non-destructively and on-line. The main motivation is to develop computationally efficient algorithm that can be implemented on a standard (low-cost) platform. In that respect we have developed a test rotating machine equipped with accelerometers, temperature sensors and sensors for lubricating oil characterization. In this paper we focus on gear-box faults and a feature extraction procedure based on non-parametric statistical concepts as suggested and demonstrated on experimental data.
Vibration Monitoring for Local Fault Detection in Synchronous Belts
Authors: Basso Roberto , Fanti Giulio
Published: July 2009

The possibility of diagnosing the presence of a fault in a synchronous belt transmission during its work, without dismantling it, by monitoring the vibrations of the pulley support, was investigated in this work. After a few simulations with a multi-body numerical model, several experimental tests were carried out in an apparatus made up of a test bench, motion sensors, a system of signal acquisition and software for data processing. The behavior of mechanical transmissions with healthy and faulty synchronous belts was compared. The damage was simulated by removing a tooth from the belt. The results show that a localized defect on a synchronous belt modifies the frequency spectrum of the motion signals measured on the pulley support. From the experimental tests performed, the following results were obtained: the direction of vibrations measured on the pulley support must be chosen so as to be parallel to the direction of the taut side of the belt; the presence of a defect can be seen in the frequency spectrum by the change in the amplitude of the peaks at the first harmonics of the run frequency; the best condition to highlight the different behaviour in the power spectra occurs when the transmission is under load.
The Dynamic of an Autoparametrical System With Two Coupled Pendulums Connected by SMA Spring
Authors: Sado Danuta , Gajos Krzysztof
Published: July 2009

The nonlinear dynamics of a three degree of freedom autoparametric system with two pendulums connected by SMA (Shape Memory Alloys) spring in the neighborhood internal and external resonance is presented in this works. The system consists of the body of mass m1 which is hung on a spring and a damper, and two connected by SMA spring pendulums of the length 1 and masses m2 and m3 mounted to the body of mass m1. It is assumed, that the motion of the pendulums are damped by resistive forces. Shape memory alloys have ability to change their material properties, for example stiffness. The equations of motion have been solved numerically and there was studied the influence of temperature on the energy transfer between modes of vibrations. Solutions for the system response are presented for specific values of the parameters of system. It was shown that in this type system one mode of vibrations may excite or damp another mode, and that except different kinds of periodic vibrations there may also appear chaotic vibrations. It depends on various amplitudes of excitation, frequencies ratio and different system parameters. Also fundamental is the influence of temperature on response of the system. For the identification of the responses of the system various techniques, including chaos techniques such as bifurcation diagrams and time histories, power spectral densities (FFT), Poincare` maps and exponents of Lyapunov may be use.
In-Accuracy Sources in Engineering Computations and Getting Them Over
Authors: Sandler B. Z.
Published: July 2009

Engineering work deals with a wide number of methods and techniques for determination or estimation the sought values: such as dimensions, amounts, stresses, tensions, deformations, forces, torques and moments of inertia, modules (for gears), powers, speed, accelerations, amplitudes, frequencies...
Beyond Lean Manufacturing: Developing an Integrated Methodology to Design Effective Manufacturing Systems
Authors: Cantamessa Marco , Montagna Francesca
Published: July 2009

Global competition forces manufacturing companies to operate deep changes in their production systems, involving physical resources, operating procedures and the organization. In this context, the Lean Manufacturing (LM) paradigm is quite popular and lean practice efforts have crossed from the automotive sector into other industries. Most academic contributions to literature concerning LM are on specific aspects of LM, while there is little discussion on the overall implementation of LM. This is despite the fact that lean principles encompass all aspects of manufacturing operations and the need of a systemic approach is clearly shown in practitioner-oriented literature. A number of factors (i.e. cultural, technological and industrial differences) may influence or inhibit the implementation of LM. This paper focuses on some of the critical aspects of LM and analyzes the reason why LM principles are difficult to implement. In particular it suggests that, by formulating a solid scientific basis, the application of LM in industry could become easier and more rigorous, and not only based on past experience. At the same time, the paper suggests that when theory-based tools are used in an isolated way, this carries the risk of not effectively coping with the systemic nature of manufacturing systems. This paper proposes the idea of an innovative methodology able to lead beyond the usual concept of LM, i.e. to adopt its basic principles and systemic perspective, but following a rational and deductive approach that explicitly considers company specific features. The methodology is based on the “Systems of Systems” approach currently being used in the context of complex military initiatives and on the integration of different tools, each focused on specific aspects of the manufacturing system. The paper makes a preliminary attempt to describe how the main aspects of manufacturing systems (resources, quality management systems, production planning and control procedures, etc.) can be represented within the SoS framework and how SoS can support the rational definition of the path leading from corporate strategy to system redesign.
Study of Sheet Metal Properties to Improve Drawability of Hydroformed Parts
Authors: Shirizly A.
Published: July 2009

The increase demand for lighter, stronger, deeper and complex shape of sheet metal hysroforming parts require better understanding of the material properties. The tensile test us the “classic” test for measuring the material properties. The tensile results are use in selecting material for engineering applications and often measured during development of new materials and processes. Tensile test procedure is relatively simple and provides the engineers large selection of tensile properties (tensile strength, ultimate strength, elongation, reduction of area, strain hardening and normal anisotropy). However, during sheet metal forming and hydroforming large stress in circumferential direction are develop and reach a critical level of the material and its thickness, this cause undulation, buckling and wrinkles. The large strain measurement technique to characterize the Forming Limit Diagram (FLD) is tested to give the material limits. The aim of this work is to examine material properties and their effect on the forming capability of the Hydromecanical process in production of hemisphere parts made of materials commonly used in the aviation and aerospace industries. Experimental procedures were carried out to assess their ductility through FLD and the Forming Limit Carve (FLC). It will shown that the material limits is not constant and can be variable depend on the deformation process as well.
Stiffness Evaluation of Machines and Robots: Minimum Collinear Stiffness Value Approach
Authors: Portman Vladimir
Published: July 2009

New stiffness performance indices using the collinear stiffness value (CSV) associated with a given configuration in a working space of the machine are proposed. The CSV and its partial cases — a translational stiffness value (TSV), a rotational stiffness value (RSV), and a screw stiffness value (SSV) — have a simple and direct physical interpretation: the CSV is non-negative in singular configuration and positive in regular configurations. As a result, the minimal values of the CSV can be successfully applied to stiffness-related evaluations for all (i.e., both singular and regular) configurations. Similar to a determinant, the minimal CSV equals zero if and only if its associated configuration is singular. In regular configurations, the minimal CSV is applied to evaluation of local stiffness for a given configuration and global stiffness in the working space, wherein the established stiffness limitations are satisfied. Procedures for evaluation of the minimal CSV are developed. As an example, the absolute CSV of the Gough-Stewart platform and its relative stiffness in comparison with serial-type mechanisms are simulated. The proposed approach can be used as an effective design tool for evaluation and limitation of stiffness of machines and robots.