bluuebunny/crossref_metadata_2025 huggingface dataset:
A Numerical Study of Integrated Direct Cure Kinetics Characterization and Control for Resin Transfer Molding (RTM)
Authors: Hsiao Kuang-Ting
Published: April 2008

In Resin Transfer Molding (RTM), the fiber preform is first placed inside a mold cavity and is subsequently impregnated with liquid resin. After mold filling, the resin starts to cure and bind the fiber preform into a solid composite part. The cure cycle will affect the residual stress built during RTM and must be controlled. Traditionally, the cure cycle control is achieved through three steps: offline resin cure kinetics characterization, offline cure cycle optimization, and mold temperature control. Different from other traditional cure cycle control approaches, this paper presents an investigation to achieve an integrated cure kinetics characterization-control system by combining a newly developed direct cure kinetics characterization method with online cure cycle optimization. A methodology to seamlessly combine these components for a practicable online cure characterization-control system will be presented and demonstrated by a numerical case study. The accuracy and reliability of this methodology will be examined and discussed based on the results of the numerical case study.
Reliability of Underfilled Chip Scale Packages Attached With Heat Sink
Authors: Mahalingam Saketh , Joshi Ashutosh , Lacey Joseph , Goray Kunal
Published: April 2008

Chip Scale Packages (CSP) are ideal intermediates between Direct Chip Attach (DCA) and Ball Grid Array (BGA) technologies in terms of both size and cost. Depending upon the application, chip scale packages are either underfilled for better solder joint reliability or are attached with a heat sink to keep the operating temperature of the chip under control. In many applications, as discussed in this paper, both an underfill and a heat sink are required. Quite expectedly the addition of two more materials, heat sink and adhesive, in the board level assembly results in fresh reliability concerns. In particular, the requirements on the underfill material and the heat sink attach adhesive are more rigorous and needless to say, a proper understanding of process and material issues is needed to make such a choice. The inelastic strains experienced by the solder joint (related to the underfill) and the peeling stresses at the heat sink attach adhesive interfaces (related to the thermal adhesive) are used as metric for comparing the number of material choices that are available. Based on the results, it is shown that it is important to choose materials that are thermo-mechanically matched with the rest of the system.
Integrated Design on Structural Shape and Controller of Spin Stand for High-Speed Positioning
Authors: Ando H. , Sakai T. , Obinata G.
Published: April 2008

This paper discusses the integrated design on structural shape and controller of positioning actuators for spin stands. To allow highly flexible shape design of the mechanism for the positioning actuator and to improve the calculation efficiency in the shape optimization, this paper proposes an integrated design method in which a structural shape is defined like as a skeleton and meats and a genetic algorithm (GA) is used to search the combination of the skeleton and meats for obtaining better performance of the closed-loop system in iterative design procedure. The iterative optimization procedure includes the shape and the controller updates. It is shown in design examples that the proposed integrated design method can improve the performance of the positioning actuator according to the performance indices. Therefore, the proposed method is effective to such active mechanisms that harder specifications are assigned to the design.
Transition Process to Turbulent Flow in Porous Media
Authors: Takatsu Y. , Masuoka T.
Published: April 2008

Turbulence in porous media has attracted much interest recently, and many turbulence models have been proposed [1-12]. However, the mathematical treatments in some turbulence models have been developed without reference to the unique structure of vortices in porous media. The further development of the turbulence model and the theoretical argument in the transition flow regime need the experimental verification of the microscopic flow field in porous media, but the geometric complexity of porous media brings about technical difficulties of the measurement and the visualization. Therefore, we adopt the flow through a bank of cylinders in a narrow gap as a model for the flow through porous media, and perform the PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) techniques to examine the microscopic flow field in porous media. We have confirmed that the solid matrix in porous media plays an important role in the vortex diffusion. The large vorticity at the throat produces such vortex as the swirl flow. On the other hand, the obstruction due to the solid matrix forces such large vortex as a Ka´rma´n vortex to be dissipative. Furthermore, the present experimental results are in agreement with our model [2] for the production and dissipation of turbulence.
A Simplified Catalytic Converter Model for Automotive Coldstart Control Applications
Authors: Sanketi Pannag R. , Hedrick J. Karl , Kaga Tomoyuki
Published: April 2008

More than three-fourths of the unburned hydrocarbon (HC) emissions in a typical drive cycle of an automotive engine are produced in the initial 2 minutes of operation, commonly known as the coldstart period. Catalyst light-off plays a very important role in reducing these emissions. Model-based paradigm is used to develop a control-oriented, thermodynamics based simple catalyst model for coldstart purposes. It is a modified version of an available model consisting of thermal dynamics and static efficiency maps, the critical modification being in the thermal sub-model. Oxygen storage phenomenon does not play a significant role during the warm-up of the engine. The catalyst is modeled as a second-order system consisting of catalyst brick temperature and temperature of the feedgas flowing through the catalyst as its states. Energy balance of an unsteady flow through a control volume is used to model the feedgas temperature, whereas energy balance of a closed system is used to model the catalyst brick temperature. Wiebe profiles are adopted to empirically model the HC emissions conversion properties of the catalyst as a function of the catalyst temperature and the air-fuel ratio. The static efficiency maps are further extended to include the effects of spatial velocity of the feedgas. Experimental results indicate good agreement with the model estimates for the catalyst warm-up. It is shown that the model represents the system more accurately as compared to the previous model on which it is based and offers a broader scope for analysis.
Prototype of Microcapsule Including a Gas Bubble for Developing Shock Wave Drug Delivery Systems
Authors: Tamagawa Masaaki , Yamanoi Ichiro
Published: April 2008

This paper describes the trial of making microcapsules including a bubble for shock wave drug delivery systems and evaluation of their mechanical properties. We have proposed drug delivery systems (DDS) using shock waves in order to apply micro/nano technology in the fields of biomedical engineering. In this system, a microcapsule including a gas bubble is flown in the blood vessel, and finally broken by shock induced microjet, then drug is reached to the affected part in the body as same as traditional DDS. In this paper, the mechanism for deformation and disintegration of capsules in our previous works is reviewed, and the trials of making special microcapsules are discussed. To determine Young’s modulus of capsule membrane mentioned above, the membrane is deformed by the aspiration device and the deformation is compared with computational result by FEM.
Quick Evaluation of Crashworthiness for Nonlinear Damped Systems by Using an Analytical Linearization Method
Authors: Wang Yuqi , Low K. H.
Published: April 2008

The ability to predict crashworthiness is helpful for the cushion design. This is to minimize the impact loading on packaged products, such as drop impact loading occurring during shipment or transportation. In addition, the nonlinear characteristic of cushion system would affect the crashworthiness of the packaged goods. Therefore, an accurate analysis for the nonlinear cushion system is crucial in reliability design. However if nonlinear analysis is performed, a large computation load is required for numerical approaches; on the other hand, there is a need to include higher transcendent functions within the analytical approaches. In this paper, an analytical linearization method is applied to obtain quantitative solution in the nonlinear analysis. This method is not a numerical method, meanwhile, no high transcendent functions are considered. Therefore, the crashworthiness for nonlinear drop-impact systems can be quickly evaluated. In practical application, this method also shows good efficiency and good agreement with the experimental results.
Comprehensive Evaluation and Optimal Design for the Vehicle Handling
Authors: Zong Changfu , Guo Konghui , Guan Hsin
Published: April 2008

In this paper, a comprehensive evaluation method for vehicle handling based on the driver’s subjective evaluation to different vehicle configurations has been studied by using development driving simulator tests. An objective evaluation index is developed which consists of several individual evaluation indices affecting vehicle handling. A series of weighting factors corresponding to individual evaluation indexes are found by using the Genetic Algorithm to reach the best agreement between the objective evaluation and the average of subjective evaluation of the drivers. Simulator test scheme has been designed and carried out with 14 vehicle configurations, and subjective evaluation has been made for easy handling of vehicle by a group of drivers. A driver/vehicle close-loop system model has been established which can predict the vehicle motion of handling and stability. Vehicle design parameters and control parameters of its control system have been optimized by using the driver/vehicle close-loop system model and objective evaluation index.
Plastic Product Evaluation Based on Mold Conceptual Design
Authors: Lu Yi-Qiang , Liu Pei-Ling , Ding Xiao-Ming , Fu Qin-Rong
Published: April 2008

Severe competition in plastic product manufacturing industry is driving the product design toward first-part-correct. Up to now, plastic product design is mainly evaluated by computer-aided-engineering packages to justify the plastic moulding processes including flow, packing and cooling. At the same time, product designers rely on their experience to justify the possibility of forming products, including parting/de-moulding direction and layout design, as there is rarely practical solution on those perspectives. This paper proposes a methodology to evaluate plastic product design based on downstream mould conceptual design probability. Several aspects of the conceptual mould design, from parting direction, undercut, draft angle to overall layout are studied. A novel undercut detection algorithm which extends the Z-Map to two sets of faces and sub-cells is proposed, and a hybrid parting direction detection mechanism is worked out. A prototype system is developed to help product designers to evaluate their designs based on the mould conceptual design perspectives. The system is tested with dozens of industrial parts and results show that the system can help the plastic part and mould designers to evaluate the designs before they are finalized.
Journal Motion Simulation of Hybrid Journal Bearing Considering Viscosity Variation Due to Temperature Change
Authors: Kumar Vijay , Sharma S. C. , Jain S. C.
Published: April 2008

A journal bearing system, if journal is disturbed from its equilibrium position, experiences change in the hydrodynamic forces acting on it. This disturbs the equilibrium of the journal and makes its center to whirl around the static equilibrium position. The dynamic response of a journal bearing system under these conditions can be obtained using either linear or non-linear equation of journal motion. The present work is aimed to determine realistic dynamic response of hole-entry hybrid journal bearing system compensated with constant flow valve restrictor. In this paper, the nonlinearized dynamic response of the journal bearing system is studied by considering two cases of journal mass (MJ) with respect to critical mass (Mlc obtained from linear analysis. i.e MJ = Mlc and MJ > Mlc. The deviation in stability margins is established by comparing the results obtained from the linearized and nonlinearized stability analysis for each case namely, isothermal, elastohyrdostatic, thermohydroststic and thermoelastohydrostatic. The coupled solution of Reynold’s, energy, conduction and elasticity equations is obtained using finite element method and the equation of motion is computed using fourth order Runga-Kutta method. The results obtained in the present work for nonlinear dynamic analysis of a constant flow valve compensated hole-entry hybrid journal bearing shows a increase in stability margin as compared to linear analysis for a case when isothermal conditions are assumed and bearing is considered rigid. When variation of viscosity with temperature is considered i.e. THS case, the stability margin is found to be about 20% higher than that estimated by linear analysis.
3D Droplet Transportation by EWOD Actuations on Flexible Polymer Films
Authors: Yang Hanping , Fan Shih-Kang , Lin Chan-Pau , Wu Chien Tai , Hsu Wensyang
Published: April 2008

3-D droplet transportation of ElectroWetting On Dielectric (EWOD) actuation with flexible substrate is proposed. Instead of glass substrate, a polymer film is taken to fabricate the microfluidic device for the droplet demonstrating out of plane motions. Two kinds of tests, tilted test and curved test, are performed, and a model of minimum required actuation voltage is presented, and compared with the results of tilted test. The current model matches experiment data much better than the conventional ones. In the curved test, the droplet successfully transports from bottom to the top.
A Continuous Model for Forced Vibration Analysis of a Cracked Beam
Authors: Behzad M. , Meghdari A. , Ebrahimi A.
Published: April 2008

In this paper the equation of motion and corresponding boundary conditions has been developed for forced bending vibration analysis of a beam with an open edge crack. A uniform Euler-Bernoulli beam and the Hamilton principle have been used in this research. The natural frequencies and the forced response of this beam have been obtained using the new developed model in conjunction with the Galerkin projection method. The crack has been modeled as a continuous disturbance function in displacement filed which could be obtained from fracture mechanics. The results show that the first natural frequency will reduce when the crack depth ratio increases. Also the rate of this reduction depends on the position of the crack. In addition it can be seen that the FRF amplitude for a cracked beam is more than a similar uncracked beam before the first natural frequency. But just after the first natural frequency the amplitude of vibration of a healthy beam is more than a cracked beam. There is an excellent agreement between the theoretical results and those obtained by the finite element method.
A Large-Scale Numerical Simulation on Bubbly and Liquid Film Flows in Narrow Fuel Channels
Authors: Takase K. , Yoshida H. , Ose Y. , Akimoto H.
Published: April 2008

In order to predict the water-vapor two-phase flow structure in a fuel bundle of an advanced light-water reactor, large-scale numerical simulations were carried out using a newly developed two-phase flow analysis method and a highly parallel-vector supercomputer. Conventional analysis methods such as subchannel codes need composition equations based on many experimental data. Therefore, it is difficult to obtain highly prediction accuracy on the thermal design of the advanced light-water reactor core if the experimental data are insufficient. Then, a new analysis method using the large-scale direct numerical simulation of water-vapor two-phase flow was proposed. The coalescence and fragmentation of small bubbles were investigated numerically and the bubbly flow dynamics in narrow fuel channels were clarified. Moreover, the liquid film flow inside a tight-lattice fuel bundle which is used to the advanced light-water reactor core was analyzed and the water and vapor distributions around fuel rods and a spacer were estimated quantitatively.
Determination of Cutting Conditions for the Stable Milling of Flexible Parts by Means of a Three-Dimensional Dynamic Model
Authors: Campa F. J. , Lo´pez de Lacalle L. N. , Bravo U. , Herranz S. , Ukar E.
Published: April 2008

In this paper, a three-dimensional dynamic model for the prediction of the stability lobes of high speed milling is presented considering the combined flexibility of both tool and workpiece. The aim is to avoid chatter vibrations in the finish milling of aeronautical parts that include thin walls and thin floors, taking into account the variation of the dynamic properties of the workpiece during machining. Hence, the accurate selection of both axial depth of cut and spindle speed can be accomplished. The model has been validated by means of a test device that simulates the behaviour of a thin floor. The following methodology is applied: first, a modal analysis of the test device is performed, second, stability lobes are calculated, and finally, a milling test validate the approach. Vibration signals from machining have been analysed to detect the chatter vibrations. The lobes diagrams obtained considering only the machine or only the tool are not in touch with reality; only through consideration of the relative frequency response function, the real borderline of stability can be obtained.
Model and Control for Hydraulic Excavator’s Arm
Authors: Zhang Daqing , He Qinghua , Hao Peng , Zhang Xinhai
Published: April 2008

To control excavator’s arm and realize autonomous excavation, firstly, full kinematic and dynamic models of the excavator arm, regarded as a planar manipulator with three degrees of freedom, were derived. Secondly, experiment excavator was retrofitted with electrohydraulic proportional valves, associated sensors, and a computer control system; then, the full nonlinear math model of electrohydraulic proportional system was achieved. Thirdly, this paper presents a discontinuous projection based on an adaptive robust controller to approximate the nonlinear gain coefficient of the valve and the nonlinear of the whole system, the error is deal with robust feedback and an adaptive robust controller was designed. Finally, the experiment of the boom motion control is presented to illustrate the feasibility. These efforts had resulted in new control design methodologies that were applicable to several hydraulic proportional systems.
Experimental Analysis of Laminated Fibrous Micro-Composite E-Springs for Vehicle Suspension Systems
Authors: Elmoselhy Salah A. , Azzam Badr S. , Metwalli Sayed M.
Published: April 2008

Laminated fibrous micro-composite E-spring is an optimized trend of springs for vehicle suspension systems. The mechanical and frequency-response-based properties of these springs are investigated experimentally at both of the structural and constitutional levels. Thermoplastic-based and thermoset-based fibrous composite structures of the E-springs are modified at micro-scale with various additives and consequently they are compared. The experimental results reveal that additives of micrometer-sized particles of E-glass fibers as well as mineral clay to an ISO-phthalic polyester resin of the micro-composite E-spring can demonstrate superior characteristics that can surpass those of the traditional steel springs. Accordingly, micro-composite E-springs can displace both of the hydraulic dampers and steel springs in both of the passive and semi-active suspension systems in a reliable, simple, and cost-effective way.
A Stress Analysis of Stepped Lap and Scarf Adhesive Joints Under Static Tensile Loadings
Authors: Sawa Toshiyuki , Sasaki Masahiro
Published: April 2008

The stress variations and stress distributions in scarf and stepped-lap adhesive joints of similar adherends under static and impact tensile loadings were analyzed in elastic range using three-dimensional finite element method. The impact loadings were applied to the lower adherend by dropping a weight. The stress distributions in scarf adhesive joints of similar adherends under static tensile loadings were also analyzed using FEM. The effects of Young’s modulus of the adherends, the adhesive thickness, and the angle of the adherends on the stress distributions at the interfaces between the adherends and the adhesive were examined under static loadings. The maximum value of σ1 decreased as young’s modulus of the adhesive increased in the stepped-lap adhesive joints under static loadings. However, the result of the scarf adhesive joints under static loadings was opposite to the above result. The value of σ1 became minimum when the scarf angle was 52°in the scarf adhesive joint. In addition, the experiments to measure the strain response and strain of joints subjected to impact and static tensile loadings were carried out using strain gauges. Fairly good agreements ware found between the numerical and the measured results.
Modal Based Correction Methods for the Placement of Piezoceramic Modules
Authors: Rose Michael
Published: April 2008

Conventional Finite-Element programs are able to compute the vibration response of mechanical structures. Increasingly also so-called multi-field problems can be solved. For piezoelectric actuators and sensors, electrical degrees of freedom apart from the mechanical ones have to be considered too. The pure actuator effect can also be modelled using the coefficients of thermal expansion. But regarding the optimal placement of flat piezoceramic modules, which couple in the mechanical part through the d31-effect, it proves to be advantageous to consider them after doing the computational complex modal analysis. In this paper, this modal coupling approach is described in detail. It introduces an additional modelling error, because the effect of the stiffness and mass of the modules is not considered in the construction process of the functional space, from which modal shapes are derived. But due to the comparatively small contribution to the global mass and stiffness of such flat devices, this additional error can generally be accepted. Furthermore this error can be reduced to an arbitrarily small amount, if the number of retained eigenmodes is increased and the gain in computational speed is significant. For the calculations, self-written triangle elements with full electro-mechanical coupling have been used, being coded completely in MATLAB. Finally the optimization procedure for the placement of the piezoceramic modules including their mass and stiffness is demonstrated for a test structure.
Numerical Simulation of Oscillatory Marangoni Flow in Encapsulated Liquid Bridge
Authors: Peng Lan , Li You-Rong , Imaishi Nobuyuki , Zeng Dan-Ling , Chen Qing-Hua
Published: April 2008

The physical and mathematical models of the Marangoni convection of KF-96 silicone oil and FC-70 fluorinart in an encapsulated liquid bridge were established. To contrast to this configuration, the Marangoni convection of KF-96 silicone oil in a liquid bridge was also studied in present work. We conducted a series of unsteady two-dimensional numerical simulations. Simulation conditions correspond to those in the experiments of Majima and Kawamura (2001). The simulation results with large Marangoni number (Ma) predicted oscillatory flows under microgravity. The critical conditions for the onset oscillatory flow were determined and compared with the experimental results. Details of the flow and temperature fields were discussed. Oscillation frequencies were also exhibited.
Tool-Wear Monitoring and Control
Authors: Srinivas J. , Dukkipati Rao , Sreebalaji V. , Ramakotaih K.
Published: April 2008

This paper presents, a control methodology based on experimental data of the tool wear as a function of cutting variables. In automatic machine tools there is strong need to control the tool wear by adjustment of the cutting parameters. In this connection, a control system, which can adjust the cutting parameters for a desired wear rate, is necessary. A regression relation is also established between the flank-wear and the cutting parameters. An inversely trained neural network model, which supplies the modified values of the cutting parameters, is used as a controller. The results are shown in the form of tables and graphs.
Design and Fabrication of a CMOS-MEMS Thermoelectric Infrared Microsensor
Authors: Liao Ke-Min , Chiou Da-Hong , Lin Keng-Shun , Chen Rongshun
Published: April 2008

This paper describes a thermoelectric infrared (IR) microsensor which is designed and fabricated using commercial CMOS IC processes with subsequent bulk-micromachining technology. The key feature of this sensor is that the thermocouples have been placed under the IR absorbing membrane. This infrared microsensor has the advantages of high fill factor, low noise equivalent temperature difference (NETD), and broad bandwidth. Finite element analysis has been conducted to simulate the heat transfer behavior of the device and to demonstrate the feasibility of our design. Besides, the experimental setup has been built for measuring the infrared sensor response. The results show a measured responsivity of 63 V/W and a thermal time constant of 10 ms.
Finite Element Modeling Strategy for Spot Welds in Thin-Walled Sections and Its Validation
Authors: Sawai N. P. , Ingle R. B. , Patidar S. K. , Mahajan R. S. , Raju S.
Published: April 2008

The effects of spot weld model on the numerical simulation of spot welded closed top-hat section sheet metal beams subjected to quassistatic and impact loading conditions were investigated using coupled experimental-numerical approach. Strength tests were performed to find the stiffness curves of spot weld in lap-shear, cross-tension (opening load), in-plane rotation (torsion) and peel specimens. The specimens were made from plain carbon steel and high strength low alloy steel sheets of three representative thicknesses. The local weld properties obtained from these tests were used to model a spot weld using different element types available in LSDYNA. These models were used in the numerical simulation of the beams subjected to static and dynamic axial crushing and static bending. The results obtained from the numerical analyses were validated by experiments on spot welded top-hat section sheet metal beams.
Microcellular PP-CaCO3 Nanocomposites: Relationship Between Nanocomposite Morphology and Foam Morphology
Authors: Huang Han-Xiong , Wang Jian-Kang
Published: April 2008

Polymeric nanocomposites exhibit high potential as a new material for carbon dioxide (CO2) foaming. In this paper, a polypropylene (PP)/nano-calcium carbonate (nano-CaCO3) composite was selected to investigate the relationship between nanocomposite morphology and foam morphology. Nanocomposites were prepared using a twin-screw extruder with screw including both shearing and mixing elements. Nanocomposites with different morphology via changing the nano-CaCO3 content were then foamed by using supercritical CO2 in a batch system. Effect of nano-CaCO3 content on the volume expansion ratio, and cell coalescence were studied.
Calculation of Thermal Conductivity in Nanofluids From Atomic-Scale Simulations
Authors: Wu Xuan , Kumar Ranganathan , Sachdeva Parveen
Published: April 2008

Nanofluids that consist of nanometer sized particles and fibers dispersed in base liquids have shown the potential to enhance the heat transfer performance. Although three features of nanofluids including anomalously high thermal conductivities at very low nanoparticle concentrations, strongly temperature dependent thermal conductivity and significant increases in critical heat flux have been studied widely, and layering of liquid molecules at the particle-liquid interface, ballistic nature of heat transport in nanoparticles, and nanoparticle clustering are considered as the possible causations responsible for such kind of heat transfer enhancement, few research work from atomic-scale has been done to verify or explain those fascinating features of nanofluids. In this paper, a molecular dynamic model, which incorporates the atomic interactions for silica by BKS potential with a SPC/E model for water, has been established. To ensure the authenticity of our model, the position of each atom in the nanoparticle is derived by the crystallographic method. The interfacial interactions between the nanoparticle and water are simplified as the sum of interaction between many ions. Due to the electrostatic interaction, the ions on the nanoparticle’s surface can attract a certain number of water molecules, therefore, the effect of interaction between the nanoparticle and water on heat transfer enhancement in nanofluids is studied. By using Green-Kubo equations which set a bridge between thermal conductivity and time autocorrelation function of the heat current, a model which may derive thermal conductivity of dilute nanofluids that consist of silica nanoparticles and pure water is built. Several simulation results have been provided which can reveal the possible mechanism of heat enhancement in nanofluids.
Embedding and Multiplexing Large Scale Sensor Arrays for Digital Clay
Authors: Zhu Haihong , Book Wayne J.
Published: April 2008

Digital Clay is proposed as the next generation human-machine communication interface with a morphing, tangible and haptic shape / surface. It is composed of a large array of hydraulic actuators in a planar pin-rod style and corresponding control system. It will be constructed using MEMS technology ultimately to satisfy the resolution, manufacturing and cost requirements. Per the ultimate objective, Digital Clay may have 10,000 to 1,000,000 actuators and, consequently, an array of sensors of similarly large numbers. In this paper the sensing system of the Digital Clay is investigated and solutions are given for current and future implementation.
Miniaturization of Energy Conversion Systems: Energetic Analysis
Authors: Sasso Maurizio , Scuto Vincenzo , Vanoli Giuseppe Peter
Published: April 2008

A great number of research groups and manufacturers are involved in the development of micro energy conversion systems. In particular the analysis is focused on heat exchangers and it deals with several aspects, such as the physical principles regulating heat and mass transfer in microchannels and the production process itself. Many benefits are expected from the on going process, such as improvement of the heat exchange, improved performances with partial loads, the opportunity to use innovative materials. On the other hand this process, started within the industrial sphere, could be boosted by the necessity of less costly production processes, through the cost reduction for materials and power, and through economy of scale. This paper aims to confirm if the actual trend of miniaturisation drives to effective benefits in terms of energy saving. For this purpose various aspects influencing the efficiency of the energy conversion devices are considered. For the efficiency of the global system (user, device and connection), special attention is paid to find the optimal trade off between the advantages due to the reductions of ducting and cycling losses and the disadvantages due to the negative influence of the size on the system’s performance.
Determination of Micro Channels Die Texturing for Enhancing Tribological Conditions in Tube Hydroforming
Authors: Ngaile Gracious , Alvarado Angel
Published: April 2008

Tube hydroforming is a process that is used to manufacture rigid light-weight parts with complex cross sections by applying an internal hydraulic pressure, in combination with axial feeding or axial compressive loading. Tribological conditions in tube hydroforming (THF) are extremely important, since these conditions have a high influence in the final geometric characteristics and mechanical properties of the part formed by the THF process. In this study, the main objective is to develop a surface texture (which is composed of engraved micro channels) that will improve Tribological conditions at the die/tube interface during the expansion process in tube hydroforming. The characteristic material movement that occurs under a desired state of Tribological conditions can be used in order to design a die textured surface. Therefore, observation of this “trend” is of paramount importance for selecting the parameters that will yield a proper design (e.g. micro channel depth, channel geometry, engraved channel density). More specifically, instantaneous local material velocities, local surface enlargement and the state of stress can be observed via numerical simulations. This paper present strategies and preliminary analysis for determining micro channel die texturing to enhance tribological condition in THF.
Optimization Based Design for Integrated Powertrain Control With Electronic Throttle
Authors: Kim Daekyun , Peng Huei , Bai Shushan , Maguire Joel M.
Published: April 2008

A process to design the control algorithm for an integrated powertrain system is proposed in this paper. The driver accelerator pedal position is first measured and interpreted as a power request. This power request is then satisfied by coordinating the transmission gear shift and the throttle position. The Dynamic Programming (DP) technique is used to obtain the optimal gear shift and throttle position for each predetermined constant power demands over a time horizon. The optimal results at different power levels are then combined to form a gear map and a throttle map. Flexible control architecture is presented where the relationship between the accelerator pedal rotation angle and the throttle opening angle can be adjusted according to the preference of the targeting customer group. Simulation and dyno test results show that the proposed integrated control scheme provides smooth constant power and improves fuel efficiency compared with the conventional transmission control scheme.
Control of Constrained Flexible Manipulators
Authors: Kilicaslan S. , Ozgoren M. K. , Ider S. K.
Published: April 2008

A new method is proposed for the end-effector motion and contact force control of flexible robot manipulators. The dynamic equations of flexible manipulators are partitioned as pseudostatic equilibrium equations and deviations from them. The pseudostatic equilibrium considered here is defined as a hypothetical state where the end-effector motion variables have their desired values while the elastic deformation variables are instantaneously constant. Then, the portion of the control torques for the pseudostatic equilibrium and the portion for the feedback stabilization of the deviations are generated using the measurement signals taken from the end-effector force and moment sensors, the strain gages and the joint encoders or the tip position sensors. The performance of the proposed method is illustrated on a planar two link robot with flexible forearm which is constrained to move on a cylindrical surface.
Model Reference Adaptive Tracking Control of Nonminimum Phase Marine Vehicles
Authors: Morel Yannick , Leonessa Alexander
Published: April 2008

The most commonly used propulsion system for marine vehicles is a propeller, generating thrust, and a stern rudder, used for steering. Motion control of a vehicle equipped with such a propulsion system can prove rather challenging. Indeed, the vehicle will not only be underactuated, but also nonminimum phase. Classically, the undesirable effects of the nonminimum phase nature of the system will translate into attitude issues. In this paper, a model reference adaptive controller that satisfactorily solves the tracking problem for a nonminimum phase model of marine vehicle is presented, along with an expression of the zero-dynamics. Using Lyapunov theory and introducing carefully chosen tracking errors, we study the closed-loop system stability and relate the behavior of the zero-dynamics to a relevant design constant.
On Transverse Vibrations of Rectangular Plates of Unidirectional Parabolic Thickness Variation
Authors: Caruntu Dumitru I.
Published: April 2008

This paper presents an approach for finding the solution of partial differential equation describing the motion of transverse vibrations of rectangular plates of unidirectional convex parabolic varying thickness. The partial differential equation consists of three operators: fourth-order spatial-dependent, second-order spatial-dependent, and second-order time-dependent. Using the method of multiple scales, the partial differential equation has been reduced to two simpler partial differential equations which can be analytically solved and which represent two levels of approximation. The first partial differential equation was a homogeneous equation and consisted of two operators, the fourth-order spatial-dependent and second-order time-dependent. Using the factorization method, so-called zero-order approximation of the exact solution has been found. The second partial differential equation was an inhomogeneous equation. Its solution, so-called first-order approximation of the exact solution has been found. This way the first-order approximations of the natural frequencies and mode shapes are found. Various boundary conditions can be considered. The influence of Poisson’s ratio on the natural frequencies and mode shapes could be further studied using the approximations reported here. This approach can be extended to nonlinear, and/or forced vibrations.
Experimental and Theoretical Investigation of Heat Transfer in Vortex Combustion Engines
Authors: Farvardin E. , Saidi M. H. , Ghafourian A.
Published: April 2008

Heat transfer phenomenon in a recently developed vortex engine has been surveyed. Cooler walls, better combustion performance and more stable relative to the other engines, make these engines very interesting. These advantages have been obtained by using a bidirectional swirl flow, containing a cool outer and a hot inner vortex, traveling upstream and downstream respectively. The most eminent benefit of these combustion chambers, having highly reduced wall temperature, is the result of convective heat release from the wall by the outer vortex. A thorough numerically and experimentally investigation has been performed on radiation and convection heat transfer to realize the exact heat transfer behavior of this engine. Results from flame structure observation indicate that flame area is much larger in vortex engine in comparison to regular engines due to vortex stretching of the flame which increases radiation heat transfer to walls. In spite of this increase, heat removal by outer swirl flow is high enough not only to compensate for increased radiation but also reduces the wall temperature substantially.
Manufacturing System Development for Fabrication of Bone Scaffold
Authors: Lu Lin , Dembzynski Robert S. , Mondrinos Mark J. , Wootton David , Lelkes Peter I. , Zhou Jack
Published: April 2008

Musculoskeletal conditions are a major health concern in United States because of a large aging population and increased occurrence of sport-related injuries. The need for bone substitutes is especially important. Traditional treatments of bone-defect have many of limitations. Bone tissue engineering may offer a less painful alternative to traditional bone grafts with lower risk of infection. This research integrates biomimetic modeling, solid freeform fabrication (SFF), systems and control, and tissue engineering in one intelligent system for structured, highly porous biomaterials, which will be applied to bone scaffolds. Currently a new SFF-based fabrication system has been developed, which uses a pressurized extrusion to print highly biocompatible and water soluble sucrose bone scaffold porogens. To date, this system can build simple bone structures. In parallel we are utilizing a commercial rapid prototyping (RP) machine to fabricate thermoplastic porogens of various designs to determine the feasibility of injecting a highly viscous scaffold material into porogens. Materials which have been successfully used to make scaffolds by injection include calcium phosphate cement (CPC), molten poly-caprolactone (PCL), 90/10 and 80/20 (v/v %) composite of PCL and calcium phosphate (CaPO4,). Results presented for the injection method include characterization of attainable feature resolution of the RP machine, as well as preliminary cell-biomaterial interaction data demonstrating biocompatibility of CPC scaffolds. The preliminary results using a commercial rapid prototyping machine have demonstrated that the indirect porogen technique can improve 2–4 folds the resolution of SFF system in fabricating bone scaffolds. The resultant scaffolds demonstrate that the defined porous structures will be suitable for tissue engineering applications.
An Engineer’s Guide to Patents
Authors: Rowland William C.
Published: April 2008

Most people learn about patents and other forms of intellectual property after it is too late. In other words, they try to obtain a patent after someone else has already stolen their invention. Or, they learn about a competitor’s patent after they have already infringed it. At this point in time, it is usually too late to get a patent, or untangling the infringement issue is very expensive. The purpose of this paper is to enable people to protect their invention before it can be stolen and to carefully monitor their competitors’ patents before they design and introduce a new product. Of course, working within the patent system is frequently complicated. However, it is almost always far easier and less expensive to take precautionary steps before problems arise than it is to resolve such problems after they have been created. The loss to an inventor for failing to protect an invention is difficult to calculate, and largely depends upon the success of the invention. Defending against a patent infringement lawsuit can easily run into the millions of dollars. Thus, one is advised to take certain precautions prior to designing, inventing, and/or introducing a new product. This paper includes three sections. The first section provides a basic primer, which is intended to provide the reader with enough background information concerning patents so that the remainder of the paper can be easily understood and applied. The second section of this paper explains what steps should be taken to protect one’s invention against copying by a competitor. The third section of this paper explains how to minimize the likelihood that a new product or method being introduced on the market will not infringe any competitor’s patents.
Performance Predictions of a Hydrogen-Enhanced Natural Gas HCCI Engine
Authors: Raitanapaibule K. , Aung K.
Published: April 2008

The characteristics of HCCI engines were numerically investigated by CHEMKIN software, CHEMKIN 4.0. Cylinder temperature and pressure, ignition delay time, peak temperature and pressure, indicated work, indicated power and IMEP were performed for the analysis the HCCI combustion of Methane and Hydrogen. The natural gas can be represented as the Methane (CH4), which is the main ingredient. The simulation evaluations were done by increasing the initial concentrations of H2, changing the initial temperature (inlet temperature), or varying the equivalence ratio. The numerical simulations were accomplished using CHEMKIN Suite from Reaction Design and the results are focused on ignition time, peak temperature, and indicated power. The effect of hydrogen addition to methane increases peak temperature and pressure, decreases ignition delay time, and increases indicated power.
Optimization of CNC Cutting Parameters by the Electrical Power Method: Turning Case
Authors: Romo E. Gutierrez , Caldero´n J.
Published: April 2008

As machining processes become one of the most common kinds of manufacturing processes in industry, it becomes imperative to optimize cutting parameters in order to reduce machining times and increase surface quality. This is specially true when piece geometry demands high rates of material removal. In previous work by the authors, piezoelectric dynamometers have been used to find cutting forces which in turn allows finding of optimal cutting parameters. Although the methodology reported has proved to be very effective, its application in the production line has not been straightforward as the use of a piezoelectric dynamometer requires an expensive setup and skilled technicians. The objective of this work is to propose and validate an experimental methodology that allows the determination of optimal cutting parameters for material-tool pairs by measuring the electrical power consumed by the machine-tool during cutting. This latter approach is more economical and easy to apply in the manufacturing line. Optimized parameters obtained through this methodology yield improvements up to more than twice on removal rates compared to those recommended by tool suppliers for the same process requirements.
A Fracture Mechanics Model for the Repair of Microcantilevers by Laser Induced Stress Waves
Authors: Leseman Zayd C. , Koppaka Sai , Mackin Thomas J.
Published: April 2008

A fracture mechanics model was developed, and experimentally verified, to model stress wave repair of stiction-failed microcantilevers. This model allows us to predict accurately the number of laser pulses, at a specific fluence and wavelength, required to fully repair stiction-failed microcantilevers. The proposed fracture mechanics model includes the strain energy stored in a stiction-failed microcantilever and the strain energy supplied by laser induced stress-waves propagating in the material. The ‘unstuck’ portion of the microcantilever is modeled as a crack so that crack growth reduces the stiction-failed length of the microcantilever. A full range of experiments have been performed to validate the model. Experiments using laser fluences ranging from 0.5 kJ/m2 – 45 kJ/m2 at two different wavelengths have been performed. The experiments are in good agreement with the model predictions. Additionally we have identified practical ranges for irradiation, including a lower bound fluence below which repair is impractical, and an upper bound above which damage to the substrate and microcantilevers occurs.
Electrohydrodynamic Conduction Pumping of Dielectric Liquids With Zero Drag Electrodes in Macro and Micro Scale Channels
Authors: Solanki Snehil , Arikapudi Ravi Kiran , Seyed-Yagoobi Jamal
Published: April 2008

In electrohydrodynamic (EHD) conduction pumping, charges generated by dissociation-recombination reaction in the liquid are redistributed by an applied electric field, resulting in the formation of heterocharge layers around the electrodes. The electric body-forces in the heterocharge layers are responsible for the fluid motion. In this study, theoretical/numerical study of EHD conduction pumping of a liquid using flat, embedded in the channel wall, electrodes is presented. This is extremely useful in pumping of liquids in small channels, as the electrodes do not penetrate into the liquid. A group of non-dimensional parameters is introduced. The operating conditions such as the applied voltage between the electrodes, the dimensions of electrodes, separation between the electrodes, the liquid properties are embodied into the set of non-dimensional parameters. Dimensionless numerical solutions are obtained illustrating the flow field under various operating conditions. The numerical solutions show that the EHD conduction phenomenon can generate pressure heads and net flow with electrodes as part of the channel wall, with minimal electric power consumptions.