bluuebunny/crossref_metadata_2025 huggingface dataset:
Series Solution and Stress Analysis of Rectangular Plate With Mixed Boundary Conditions
Authors: Liu Jiemin , Liu Jintang , Sawa Toshiyuki
Published: April 2008

Stress functions expressed from Fourier series, suitable for arbitrary stress boundary conditions, were derived using method of variable separation. General displacement expressions containing the displacement of rigid body were also derived. A method of solving mixed boundary problems (in which external forces acting at a part of the whole boundaries are known and displacements at the rest boundaries are known) was presented. As an example, a rectangular plate, one side of which was fixed and objective side was subjected to a concentrated force, was analyzed. In addition, characteristics of stress distributions in the regions of stress concentration were questioned. It was found from the presented results of calculation that describing stress concentration with the singular stress at a point was unworkable. Describing stress concentration with the average stress in the feature size instead of the singular stress at a point was operative and reflected objectively practical stress and displacement boundary conditions. The concept of feature-size-factor was introduced.
Applications of PhotoModeler in Accident Reconstruction
Authors: Toglia Angelo , Stephens Gregory D. , Michalski David J. , Rodriguez Joy L.
Published: April 2008

Photographic methods of analyzing vehicles and scenes for the purpose of accident reconstruction have been well researched and documented. Photogrammetric analysis has appeared in various forms and levels of complexity over the years. Mathematical relationships have been researched and presented depicting the methods and bases of these techniques. This paper will present some new tools and methodologies in the process of photographic analysis. The PhotoModeler program will be utilized to demonstrate applications of digital photogrammetry in the field of accident reconstruction. Several different methodologies, including single and multiple photograph projects using calibrated and inverse cameras, will be evaluated and demonstrated. Additionally, comparisons to traditional methods of measurements will be presented. It will be demonstrated that the use of digital photogrammetry has advanced the science of accident reconstruction by employing computer and digital technology to achieve greater efficiency and improved accuracy.
Evaluating the Economic Impact of Harmonized Product Standards in the European Union
Authors: Aanstoos Ted A. , Schmiemann Manfred
Published: April 2008

After its 2004 enlargement to 25 member nations, the European Union, with a population of 452 million and a GDP surpassing $10 trillion, represents one of the most powerful economic engines in the world, and is the primary trading and investment partner with the US. However, in spite of the mostly integrated single market in Europe, internal trade between member nations can be hindered by competing national level technical standards. To address such inefficiencies, the European Commission issues standardization directives under the New Approach doctrine, adopted in 1985 to harmonize product standards in Europe. This paper attempts to evaluate the effectiveness of the New Approach by analyzing European production and trade data, internal and external, of certain products governed by New Approach norms, in order to determine if economic activity in those products was significantly impacted by the streamlined standards, while controlling for other socioeconomic factors.
Development of Mg/Cu Nanocomposites Using Microwave Assisted Powder Metallurgy Technique
Authors: Wong W. L. E. , Gupta M.
Published: April 2008

In the present study, magnesium composites containing different amount of nano-size copper particulates were successfully synthesized using powder metallurgy technique coupled with a novel microwave assisted rapid sintering. Mg/Cu nanocomposites were sintered using a hybrid heating method consisting of microwaves and radiant heat from external susceptors. The sintered specimens were hot extruded and characterized in terms of microstructural, physical and mechanical properties. Microstructural characterization revealed minimal porosity and the presence of a continuous network of nano-size Cu particulates decorating the particle boundaries of the metal matrix. Mechanical characterization revealed that the addition of nano-size Cu particulates lead to an increase in hardness, 0.2% yield strength (YS) and ultimate tensile strength (UTS) of the matrix. An attempt is made in the present study to correlate the effect of increasing presence of nano-size Cu reinforcement on the microstructural, physical and mechanical properties of monolithic magnesium.
Sliding Mode Tracking Control of Underactuated Surface Vessels
Authors: Ashrafiuon Hashem , Ren Ping
Published: April 2008

This paper presents a position tracking controller for underactuated autonomous surface vessels. An asymptotically stable model-based tracking control algorithm is proposed for surface vessels based on sliding mode control approach since it is capable of handling large parameter uncertainties, unmodeled dynamics, and disturbances. A simple three-degree-of-freedom planar model of a surface vessel is presented with two actuator inputs providing surge and yaw motions. Two sliding surfaces are defined based on the vessel’s tracking errors. A first order surface is defined in terms of the surge position and velocity tracking errors. This leads to the calculation of the surge control force. A second order surface is then defined in terms of the vessel’s lateral position, velocity, and acceleration tracking errors. This surface lets us determine the required yaw control moment based on the surge force. The derivation includes integration of parameter uncertainties and disturbances into the formulation. The proposed sliding controller is tested through simulation of several different position tracking problems of an autonomous surface vessel with relatively large parameter uncertainties and environmental disturbances such as waves and wind. The wind and wave models are defined in terms of environmental parameters (wave period, length, wind speed, direction, etc.) and included in the formulation. Suitable nominal values and bounds are defined in two sliding mode controllers for the model parameters and wave and wind disturbances in order to insure the control law’s robustness.
Strength Analyses of FE2O3+Al Nanocomposites Using Classical Molecular Dynamics
Authors: Tomar Vikas , Zhou Min
Published: April 2008

Classical molecular dynamics (CMD) simulation is an important technique for analyzing custom-designed nanostructured materials and nano-sized systems such as nanowires and nanobelts. This research focuses on analyzing the strength of Fe2O3+Al energetic nanocomposites using CMD. A generic potential form is used to describe the behavior of the Fe+Al+Fe2O3+Al2O3 system. The potential is able to describe bulk single crystal behavior of Fe, Al, Fe2O3, Al2O3 as well as interfacial transitions among them. The nanostructures analyzed include polycrystalline Aluminum, Fe2O3 as well as their composites with two different volume fractions (0.6/0.4 and 04/0.6). The polycrystalline structures are generated using voronoi tessellation. Quasi-static strength analyses are carried out using a massively parallel CMD code for both tension and compression. The analyses reveal that reverse Hall-Petch (H-P) effect is operative for polycrystalline Al under both tension and compression. However, for polycrystalline Fe2O3 reverse H-P effect is operative under tension only. Compression still shows direct H-P effect. This effect transcends into the strength of both composites at all grain sizes. In addition, we also observe tension-compression strength asymmetry in the all polycrystalline systems. This framework offers an important tool for nanoscale design of advanced nanocomposite materials.
High Performance Microvalve Array
Authors: Lee Dong Gun , Shin Daniel D. , Carman Gregory P.
Published: April 2008

The fabrication, analysis, and testing of a large flow rate and high frequency microvalve array are presented in this paper. The array consists of 88-microvalves fabricated on a silicon-on-insulator (SOI) substrate. The SOI wafer simplifies the fabrication process and eliminates the need for multi-layer surface micromachining process and bulk wafer-bonding procedures. The analytical resonant frequency of the valve is up to 50 kHz and operates at high delta pressures (i.e. 0.14 MPa). The microvalves are fabricated with various flap widths ranging from 300 to 400 μm and flap thickness ranging from 10 to 13 μm. The results indicate that flap displacement and flow rate are strongly dependent on flap thicknesses and to a lesser degree on flap widths increases. The resonance frequency with valve flap thickness increases and width decreases. Comparison between predicted and measured flow rate shows good agreement. A flow rate up to 35 cc/sec was measured. A failure criterion is also presented using the fracture stress analysis and shows good agreement with experimental result.
Effect on Temperature Distribution at Liner Wall for Different Equivalence Ratios of Primary Zone for Small Capacity Gas Turbine Combustion Chamber
Authors: Kulshreshtha Digvijay B. , Channiwala S. A. , Patel Jatin R.
Published: April 2008

The combustion chamber of gas turbine unit is one of the most critical components to be designed. The study of literature review reveals that much work is available pertaining to design and performance of combustion chamber. However, the systematic approach and optimized liner wall configuration is not easily traceable in the literature. This is particularly true for small capacity units. Hence there is a need for experimental optimization of combustion chamber in small capacity range. The present work aims at the experimental optimization of liner wall configuration. Four different types of combustion chambers with primary zone equivalence ratios of 0.5, 0.7, 0.9 and 1.1 are designed, developed and experimented based on which an optimal configuration is recommended. It is worth to mention that the present work clearly focuses the combustion chamber with equivalence ratio in primary zone as 0.9 as the optimal combustion chamber.
Development of a Bone Drilling Simulation System With Force Feedback
Authors: Chi Xiaoyi , Niu Qiang , Thakkar Viral S. , Leu Ming C.
Published: April 2008

We present the development of a bone drilling simulation system to simulate on a PC the drilling operations commonly used in orthopedic surgery. A drilling force model is obtained by performing regression of measured drilling force versus process and material parameters. A haptic rendering algorithm consisting collision detection and force generation is also developed. The overall simulation of the developed system runs two threads in parallel: (1) haptics thread, which obtains the position and orientation of the virtual drill and provides force feedback and (2) graphics thread, which is dedicated to real-time rendering of volumetric data.
Analysis of Clearances in Combined Screw Machines
Authors: Kovacevic Ahmed , Stosic Nikola , Mujic Elvedin , Smith Ian K.
Published: April 2008

Changes caused by differential expansion between the rotors and the casing occur in the high pressure clearances in both the compressor and expander sections when expansion and compression are performed together in a single oil free machine of the twin-screw type. These are more difficult to control than when the two functions are carried out in separate machines. The clearance changes affect both the performance and reliability of the machine but can be controlled by using different materials of construction for each section. Clearances, predicted by the assumption of linear expansion of the components, were included in a well-proven software package for performance estimation of both screw compressors and expanders and the results compared with experimental data. It was found that the clearance in the machine, being dependent on the temperature, could be estimated fairly accurately by matching measured discharge temperature and the temperature obtained by the estimation model. Therefore, a simple expansion analysis of the main machine clearances appeared to be an adequate tool for use in the design of these machines in order to optimise performance and prevent the machine seizing as a result of differential thermal expansion during operation.
Free Asymmetric Vibrations of Composite Full Circular Cylindrical Shells Stiffened by a Bonded Non-Central Shell Segment
Authors: O¨zerciyes V. , Yuceoglu U.
Published: April 2008

In this study, the “Free Asymmetric Vibrations of Composite Full Circular Cylindrical Shells Stiffened by A Bonded Non-Central Shell Segment” are analyzed and investigated in some detail. The “full” circular cylindrical “base” shell and the non-centrally bonded circular cylindrical shell “stiffener” are assumed to be made of dissimilar orthotropic materials. The “base” shell and the “stiffening” shell segment are adhesively bonded by an in-between, relatively very thin, yet linearly elastic adhesive layer. In the theoretical analysis, for both shell elements, a “First Order Shear Deformation Shell Theory (FSDST)” such as “Timoshenko-Mindlin -(and Reissner)” type is employed. The damping effects in the entire system are neglected. The sets of dynamic equations of both “base” shell and “stiffening” shell segment and the adhesive layer are combined together, manipulated and are, finally, reduced to a “Governing System of First Order Ordinary Differential Equations” in Forms of the “state vectors” of the problem. This result constitutes a so-called “Two-Point Boundary Value Problem” for the entire composite shell system, which facilitates the present solution procedure. The final system of equations is numerically integrated by means of the “Modified Transfer Matrix Method (MTMM) (with Chebyshev Polynomials)”. The typical mode shapes with their natural frequencies are presented for several sets of support conditions. The very significant effect of the “hard” and the “soft” adhesive layer on the mode shapes and the natural frequencies are demonstrated. Some important parametric studies (such as the “Joint Length Ratio”, etc.) are also presented.
Realizing 3-D Interconnected Direct Write Electronics Within Smart Stereolithography Structures
Authors: Palmer Jeremy A. , Summers Jeffrey L. , Davis Donald W. , Gallegos Phillip L. , Chavez Bart D. , Yang Pin , Medina Francisco , Wicker Ryan B.
Published: April 2008

Research in rapid prototyping of high-density circuitry (RPHDC) involves integrating direct write (DW) conductive ink dispensing technology with stereolithography (SL) to manufacture smart structural members with integrated three-dimensional electronics. A significant challenge in this effort is realizing practical three-dimensional interconnect for discrete electronic packages encapsulated within a SL matrix. This paper presents research into SL-encapsulated DW three-dimensional interconnect. Results suggest that robust three-dimensional electronics are possible within an integrated DWSL structure. A power supply circuit is demonstrated that converts a 28 VDC input to a 5 VDC output with electromagnetic interference filtering capability. Additional work is necessary to improve resistance of DW interconnect, and planarity of device planes. Strategies for improving resistance of DW ink through localized laser curing and thermal curing are discussed in addition to the encapsulation performance of advanced SL resins. Future work in this area may impact the widely accepted MCM-L and MCM-C multichip module technologies.
Uniaxial Ratchetting of SiCP/6061Al Alloy Composites at Room and High Temperatures
Authors: Kang Guozheng
Published: April 2008

The uniaxial strain cyclic characteristics and ratcheting behaviors of T6-treated SiCP/6061Al alloy composites were studied experimentally at room and high temperatures (573K). The cyclic softening/hardening and ratcheting behaviors of T6-treated composites and un-reinforced matrix were investigated in different loading conditions and with two volume fractions of SiC particulates. It is shown that the cyclic softening/ hardening and ratcheting behaviors of the composites are similar to those of the un-reinforced matrix in macro-scale, i.e., the ratcheting also occurs in the composites during the cyclic stressing with non-zero mean stress, and the ratcheting strain increases with the increasing of stress amplitude and mean stress; however, the addition of SiC particulates into the matrix increases the resistance of the composite to the ratcheting, and the ratcheting strain decreases as the volume fraction of SiC particulates increases. It can be also concluded that the cyclic deformation of the composites has a great temperature-dependence. Some significant conclusions are obtained, which are useful to construct a constitutive model to describe the cyclic deformation of the composites.
Digitized Heat Transfer for Thermal Management of Compact Microsystems
Authors: Mohseni Kamran , Baird Eric , Zhao Hongwu
Published: April 2008

Active thermal management of compact microsystems by a periodic array of discrete liquid metal droplets is proposed and referred to as “digitized heat transfer.” This is in contrast to convective heat transfer by a continuous liquid flow. Two methods of droplet actuation, electrowetting on dielectric and continuous electrowetting, are described. Liquid metals or alloys support significantly higher heat transfer rates than other fluids, such as water or air. In addition, electrowetting is an efficient method of microscale fluid control, requiring low actuation voltages and very little power consumption. These concepts are used in this investigation to design an active management technique for high-power-density electronic and integrated micro systems. Preliminary calculations indicate that this technique could potentially offer a viable cooling strategy for achieving some of the most important objectives of electronic cooling, i.e., minimization of the maximum substrate temperature, reduction of the substrate temperature gradient and removing substrate hot spots. Numerical simulation of a droplet in a microchannel is also investigated. We propose a technique for dynamically calculating the slip velocity at the wall boundary including both the advancing and receding contact lines. The technique is based on the observed non-Newtonian behavior of a continuous liquid flow at high shear rates and its associated slip velocity (Thompson and Trioan 1997). While most of the wall boundary has negligible slip, significant slip at the advancing and receding contact lines are calculated from the data itself.
Coupled Transport/Hyperelastic Model for High Nastic Materials
Authors: Homison Chris , Weiland Lisa Mauck
Published: April 2008

Work is underway to develop high energy density active materials based upon biological processes. These materials utilize the controlled transport of charge and fluid across a selectively-permeable membrane to achieve bulk deformation in a process referred to in the plant kingdom as nastic movements. The nastic material being developed consists of synthetic membranes containing biological ion pumps, ion channels, and ion exchangers surrounding fluid-filled cavities embedded within a polymer matrix. In this paper the formulation of a biological transport model and its coupling with a hyperelastic finite element model of the polymer matrix is discussed. The transport model includes contributions from ion pumps, ion exchangers, solvent flux, and ion channels. This work will form the basis for a feedback loop in material synthesis efforts. The goal of these studies is to determine the relative importance of the various parameters associated with both the polymer matrix and the biological transport components.
Scuffing Failure Due to an Abrasive Contaminant and Filter Suitability in High Pressure Injection Fuel System
Authors: Rashid Badar , Malik M. Afzaal , Khushnood Shahab
Published: April 2008

The field studies have revealed that there is an unprecedented high failure rate of rotary diesel fuel injection pump (RDFIP). The presence of rigid abrasive contaminant between the plunger and sleeve of hydraulic head assembly of RDFIP causes scuffing failure. The abrasive contaminant is modeled as a spherically shaped rigid particle. The contaminant is envisioned to penetrate into the sleeve while positioning itself in rubbing contact with the plunger. Excessive temperature rise known as flash temperature between the particle-plunger interface is used as an indication of whether scuffing would take place. Flash temperature is determined by incorporating operating speed of pump, particle size, minimum film thickness, fuel properties, thermomechanical and surface properties of plunger and sleeve. Thermomechanical properties are determined through material composition of plunger and sleeve by spectroscopic techniques. Coordinate measuring machine is used to determine the radial clearance between the plunger and sleeve. Three high-pressure injection pumps are taken as case study for obtaining experimental data. This experimental data is used as an input in our theoretical model for the determination of flash temperature duly analyzing partial and diametric penetration of the abrasive contaminant. The model uses flash temperature in conjunction with the material properties to determine the critical particle size that may result in scuffing failure. The exact rating of fuel filter based on the critical particle size of the contaminant producing scuffing failure in the plunger and sleeve of hydraulic head assembly of RDFIP is also determined. The range of critical particle size initiating significant abrasive wear is determined and validated with the experimental results available in literature.
Mechanical Neural Growth Models
Authors: Allen Kathleen B. , Layton Bradley E.
Published: April 2008

Critical to being able to control the growth patterns of cell-based sensors is being able to understand how the cytoskeleton of the cell maintains its structure and integrity both under mechanical load and in a load-free environment. Our approach to a better understanding of cell growth is to use a computer simulation that incorporates the primary structures, microtubules, necessary for growth along with their observed behaviors and experimentally determined mechanical properties. Microtubules are the main compressive structural support elements for the axon of a neuron and are created via polymerization of α-β tubulin dimers. Our de novo simulation explores the mechanics of the forces between microtubules and the membrane. We hypothesize that axonal growth is most influenced by the location and direction of the force exerted by the microtubule on the membrane, and furthermore that the interplay of forces between microtubules and the inner surface of the cell membrane dictates the polar structure of axons. The simulation will be used to understand cytoskeletal mechanics for the purpose of engineering cells to be used as sensors.
Effect of Presence of Carbon Nanotubes on the Wettability and Mechanical Performance of Sn-Ag-Cu Solder
Authors: Nai S. M. L. , Wei J. , Gupta Manoj
Published: April 2008

In this study, Sn-Ag-Cu based nanocomposites with carbon nanotubes (CNTs) as reinforcements were successfully synthesized using the powder metallurgy technique. Micron size lead-free solder particles were blended together with varying weight percentages of CNTs. Blended powder mixtures were then compacted, sintered and finally extruded at room temperature. The extruded materials were characterized for their melting temperatures, wettability and mechanical properties. Experimental results revealed that the melting temperatures of the composite solders did not have any significant changes. Wettability property of the composite solder was also found to improve with addition of reinforcements. Moreover, the results of mechanical properties characterization exhibited an increase in overall strength of the composite solders. An attempt is made in the present study to correlate the variation in weight percentages of reinforcement with the properties of the resultant nanocomposite materials. These advanced interconnect materials will benefit industries like the microelectronics flip chip assembly and packaging, MEMS systems and NEMS systems.
Investigations on the Effect of Blade Angle on Ventilated Brake Disc Using CFD
Authors: Munisamy Kannan M. , Mokhtar Hanan , Hasini Hasril , Yusof Mohd Zamri , Idris Mohd Azree
Published: April 2008

This paper presents the investigation on the effect of blade angle to the mass flow and heat transfer coefficient of a ventilated brake disc. Six different blade angle configurations are simulated using commercial computational fluid dynamics code, FLUENT. Important parameters such as mass flow rate of air through the ventilated blade and surface heat transfer coefficient are predicted and analyzed. Prediction shows reasonable estimation of mass flow rate and heat transfer coefficient on the disc brake. Linear trend is achieved on the mass flow and heat transfer coefficient as the vehicle speed increases. It is also concluded that the optimum mass flow and heat transfer coefficient are predicted at blade angle of 15°. The prediction provides an insight into the behavior of the air flow through the restricted passage of the brake disc design.
Electrorheological Properties of Suspensions Prepared From Polythiophene Conductive Polymer
Authors: Chotpattananont Datchanee , Sirivat Anuvat
Published: April 2008

Electrorheological (ER) fluids are typically composed of polarizable particles dispersed in a non-conducting fluid. Upon the application of an electric field, chain-like or fibrillar aggregates of the suspended particles are oriented along the direction of the electric field, thereby inducing viscoelasticity and a drastic increase in viscosity. In our study, Poly(3-thiophene acetic acid), PTAA, has been developed for using as ER material. The rheological properties of this PTAA suspension upon the application of electric field were investigated under various deformations; oscillatory shear flow, steady shear, and creep. We found that PTAA based ER fluid exhibited viscoelastic behavior and showed the excellent responses under an applied electric field. Moreover, the ER response of this PTAA fluid was amplified with increases in electric field strength, particle concentration, and particle conductivity. Under the oscillatory shear, the dynamic moduli, G′ and G″, increased dramatically by 10 orders of magnitude, when the field strength was increased to 2 kV/mm. The suspensions exhibited a transition from fluid-like to solid-like behavior as the field strength increased. While under steady shear flow, the yield stress increased with electric field strength, E, and particle volume fraction, φ, according to a scaling law of the form, τy α Eαφγ. Furthermore, the creep curves of this ER fluid consisted of both elastic and viscous responses and this fluid exhibits partially elastic recovery after the removal of applied stress. The creep properties strongly depended on the magnitude of an applied stress.
Electromechanical Responses of Poly (p-phenylene vinylene)/Polydimethylsiloxane Blends
Authors: Niamlangh Sumonman , Sirivat Anuvat
Published: April 2008

Electrorheological properties of PDMS gel and PPV/PDMS blend were investigated experimentally under an oscillatory shear mode at the temperature of 27 °C to determine the effects of crosslink ratio, electric field strength and doping level. For the pure PDMS gels, the storage modulus, G′, increases with increasing crosslinking ratio and electric field at all frequencies between 0.1-100 rad/s. When an electric field is applied, the polymer molecules become polarized resulting in the interaction through the electrostatic force between the polarized PDMS molecules. The PDMS gel system with the crosslinking ratio of 0.01 possesses the highest G sensitivity to electric field. For the PPV/PDMS blends (PPV/PDMS_10), the dynamic moduli, G′ and G″, are higher than those of pure PDMS in the absence of electric field because PPV particles act as a filler in PDMS matrix. The G′ sensitivity of PDMS increases up to 35 % at the electric filed strength of 2 kV/mm. Moreover, the doped PPV/PDMS blend (doped PPV (1:10)/PDMS_10) shows the highest G′ sensitivity (45 %) due to interacting electrostatic forces between electric field induced dipole moments of the conductive molecules.
Adaptive Fuzzy Gain Scheduling in Position Control of Servo Hydraulic System With Flexible Load
Authors: Yousefi Hassan , Handroos Heikki
Published: April 2008

The control of hydraulic servo-systems has been the focus of intense research over the past decades. Hydraulic position servos with an asymmetrical cylinder are commonly used in industry. These kinds of systems are nonlinear in nature and generally difficult to control. Because of changing system parameters using the same gains will cause overshoot or even loss of system stability. The highly non-linear behavior of these devices makes them idea subjects for applying different types of sophisticated controllers. This paper is concerned with a second order model reference adaptive position control of a flexible load servo-hydraulic system using a fuzzy gain scheduling. In present study, to compensate the lack of damping in hydraulic system, an acceleration feedback was used. The proposed controller was verified with a common used p-controller. The results suggest that using fuzzy controller improves all performance evaluation criteria such as stability, fast response, and accurate reference model tracking in hydraulic systems.
The Influence of Gear Hobbing on Worm Gear Characteristics
Authors: Simon V.
Published: April 2008

A method is presented for the determination of the influence of gear hobbing on the precision and loaded tooth contact of worm gears. In order to get a worm gear set with fully conjugated teeth surfaces the gear teeth should be processed by a hob whose generator surface is identical to the worm surface. This requirement can be achieved by the use of a hob whose diameter is equal to the worm diameter and with infinite number of cutting edges. But because of the teeth in the hob are relieved, the diameter of the new hob should be slightly larger than the worm diameter to provide tool life. On the other hand, because of the finite number of hob teeth, the gear tooth surface, manufactured by such a hob, is not a smooth surface; it consists of a relatively big number of small parts of helical surfaces formed by the cutting edges of the hob. In this paper a method is presented for the determination of differences between the gear tooth surface processed by an oversized hob of finite number of teeth or by a flying tool, and the theoretically required gear tooth surface. Also the influence of hob oversize and machine tool settings on tooth contact pressure and transmission errors is determined. The full geometry and kinematics of gear tooth processing by an oversized hob or by flying tool is included. The theoretical background is implemented by a computer program. By using this program, the influence of relevant design parameters of worm gear set and hob and of machine tool settings on processed gear tooth errors and on loaded tooth contact of the worm gear pair is investigated and discussed. By another computer program the influence of cutter diameter and machine tool settings for pinion teeth processing on tooth contact pattern in spiral bevel gears is investigated and presented.
Statistical Analysis of a Steering Assist Controller Using Driving Simulator Data
Authors: Chen Liang-Kuang , Ulsoy A. Galip
Published: April 2008

Human-in-the-loop driving simulator experiments are conducted to evaluate a proposed robust steering assist controller designed based upon driver uncertainty modeling. A nominal controller that is designed without consideration of driver model uncertainty is also tested for comparison. Two types of experiments are proposed. A long driving task with nominal configurations and a short driving task with initially large lateral position error. The data is analyzed using both time domain and frequency domain metrics. In the time domain, the standard deviation of lateral position error and percentage of road departure are used. In the frequency domain, the stability margins and crossover frequency are used. The driving simulator results indicate that statistically the designed robust controller shows improvements in the short driving experiments. The improvements in the long driving experiments are less evident due to driver adaptation. The non-robust nominal controller suffers from high gain and should be avoided. The benefits of considering driver model uncertainty in the design of vehicle steering assist controllers is, therefore, justified.
Legal and Ethical Considerations of Whistleblowing for Engineers
Authors: Oliver Douglas L.
Published: April 2008

According to the ethical codes of many engineering professional societies, engineers have an ethical duty to the public. For example, the ASME Code of Ethics states that engineers “shall hold paramount the safety, health and welfare of the public.” Licensed engineers (PE’s) have additional legal duties to the public imposed by state licensing agencies. Engineering regulations and ethics codes have been interpreted by many to include the duty to report illegal or unsafe conditions to governmental authorities. This paper investigates whistleblowing as it relates to engineers. This troublesome topic is investigated considering the ethical, legal, and practical implications for engineers who blow the whistle.
Multi-Purpose Dryer Pilot Plant
Authors: Chinedu Louis Onwulri
Published: April 2008

In engineering design and construction, a mathematical model with which the process parameters can be studied is of extreme utility. A reliable model will often present or minimize costly mistakes in prototype development and be utilized for the process air variable (Air flow rate, drying air temperature, drying air humidity), product variables (product throughput and size distribution), dimensional variables (width, length, height of drying, number of passes, dryer configuration can be controlled. While ambient air conditions, aerodynamic properties of the drying material, exposed surface area of the product, drying rate characteristics and equilibrium moisture contents are specific and cannot be controlled. This report incorporates the design work of, and for the construction of a multi-purpose dryer. Economic consideration lent a batch operating try dryer to the choice type. A choice feed of cassava chips (70% moisture content) to produce dried chips (1% moisture content for onward production of cassava flour is used. The drying is done adiabatically, employing heated air blown over the trays at a controlled dry bulb temperature of 110°C and wet–bulb temperature of 45 °C putting together available drying equations and simplification, a pilot plant producing 3.564kg of dried chips per batch time of 1.2936 hours (excluding loading and unloading time) is being designed under achievable operability. On and economic analysis, a pay–back time of 2.53 years is conceived. This report will be subdivided into choice of process route, process design, process economic and recommendation. It will incorporate also by useful tables, appendices and the design flow diagrams.
Hot-Spot Thermal Management With Flow Modulation in a Microchannel Heat Sink
Authors: Lee Poh-Seng , Garimella Suresh V.
Published: April 2008

Recesses created in the lid of a microchannel heat sink can serve to modulate the flow, resulting in local and global heat transfer enhancement. Numerical analysis of laminar flow and heat transfer in such a modified microchannel heat sink has shown an augmentation of heat transfer without an added penalty of increased pressure drop. The presence of the recesses reduces the overall flow friction and thus pressure drop. The flow expansion into the recesses and the subsequent contraction into the downstream region causes significant local enhancement in heat transfer. Both the maximum and average wall temperatures are decreased as a result. The heat transfer is locally enhanced, by as much as 150% in the regions just downstream of the recesses due to the re-initialization of boundary layers as the flow re-enters the microchannels. The potential for hot-spot mitigation in microelectronics devices using this approach is discussed.
Electroactive Paper Materials Coated With Carbon Nanotubes and Conducting Polymers
Authors: Kim Jaehwan , Ounaies Zoubeida , Yun Sung-Ryul , Kang Yukeun , Bae Seung-Hun
Published: April 2008

Electro-Active Paper (EAPap) materials based on cellulose are attractive for many applications because of their low voltage operation, lightweight, dryness, low power consumption, bio-degradable. The construction of EAPap actuator has been achieved using the cellulose paper film coated with thin electrode layers. This actuator showed a reversible and reproducible bending movement. In order to improve both force and displacement of this, EAPap actuator efforts are made to construct the device using increasing number of complementary conducting polymer layers and carbon nanotubes. A hybrid EAPap actuator is developed using single-wall carbon nanotubes (CNT)/Polyaniline (PANi) electrodes, as a replacement to gold electrodes. It is expected that the use of CNT can enhance the stiffness of the tri-layered actuator, thus improving the force output. Furthermore, the presence of the CNT may increase the actuation performance of the EAPap material. CNT is dispersed in NMP(1-Methyl-2-pyrrolidine), and the resulting solution is used as a solvent for PANi. The CNT/PANi/NMP solution is then cast on the EAPap by spin coating. The coated EAPap is dried in an oven. The effect of processing parameters on the final performance of the CNT/PANi electrodes is assessed. The final performance of the electrodes is quantified in terms of the electrical conductivity under dc and ac measurement conditions. The actuation output of the CNT/PANi/EAPap samples is tested in an environmental chamber in terms of free displacement and blocked force. The performance of the hybrid actuators is also investigated in terms of frequency, voltage, humidity and temperature to help shed light on the mechanism responsible for actuation. Comparison of these results in that of the EAPap with PANi and gold electrodes are also accomplished. EAPap materials are bio-degradable that is important property for artificial muscle actuators for biomimetic with controlled properties and shape.
Development of a High Sensitivity Three-Axis Force/Torque Sensor for Microassembly
Authors: Rose Scott E. , Jones James F. , Enikov Eniko T.
Published: April 2008

There is a growing need for multi-axis force torque (F/T) sensors to aid in the assembly of micro-scale devices. Many current generation robotic microassembly systems lack the force-feedback needed to facilitate automating common assembly tasks, such as peg-in-hole insertions. Currently, most microassembly operations use vision systems to align components being assembled. However, it is difficult to view high aspect ratio component assemblies under high magnification due to the resulting limited depth-of-field. In addition, this difficulty is compounded as assembly tolerances approach dimensions resolvable with optics or if the mating parts are delicate. This paper describes the development of a high sensitivity F/T sensor. Optimal design theory was applied to determine the configuration that would result in the most sensitive and accurate sensor. Calibration experiments demonstrated that the sensor can resolve down to 200μN and possibly less.
A Variational-Asymptotic Theory of Smart Slender Structures
Authors: Roy Sitikantha , Yu Wenbin
Published: April 2008

The goal of the present work is to develop an efficient simulation tool with high-fidelity to help the engineers design and analyze smart slender structures with embedded piezoelectric materials. Actuation and sensing capabilities of piezoelectric material embedded in smart beam including geometric nonlinearity will be explored. The dimensional reduction process has been carried out using the powerful Variational Asymptotic Method. Starting from the exact three-dimensional electric-mechanically coupled enthalpy functional, the asymptotical analysis is done on the functional itself with respect to the naturally occurring small parameters. The original three-dimensional electric-mechanical problem of the slender structure is decomposed into two separate problems: a two-dimensional analysis over the cross section and a one-dimensional analysis over the beam reference line. The coupled cross-sectional analysis is being implemented in VABS, a versatile cross-sectional analysis code.
High Pressure Air Compressor Condition Monitoring Using Unsupervised Pattern Classification Based on Projection Networks
Authors: Li C. James , Jansuwan C.
Published: April 2008

High pressure air compressors (HPAC) are a high maintenance machine for they break down more often than expected and they serve critical roles. This study established the utility of an unsupervised pattern classifier system integrating a clustering algorithm based on DBSCAN and a dynamic classifier based on projection network to classify the condition of a 4-stage high pressure air compressor. The clustering algorithm is used to form clusters from un-labeled data and eliminate outliers. Subsequently, a system of projection networks is established to recognize all the significant clusters. The compressor data is consisted of pressures and temperatures at all four stages taken under various conditions including different baseline conditions, 3rd stage suction valve fault, 3rd stage discharge valve fault, and cylinder pitting and corrosion. The clustering algorithm was able to form clusters that each individually contains data mostly from a single class, and the projection network was able to differentiate these clusters and therefore classify the condition of the compressor correctly about 94% of the time. The ability of unsupervised classification does come with a price of lower classification accuracy. It was about 5% lower than what was accomplished by supervised classification.
A Numerical Study on a V-Shaped Laminar Stratified Flame
Authors: Guo Hongsheng , Smallwood Gregory J. , Galizzi Cedric , Escudie´ Dany
Published: April 2008

A V-shaped laminar stratified flame was investigated by numerical simulation. The primitive variable method, in which the fully elliptic governing equations were solved with detailed chemistry and complex thermal and transport properties, was used. The results indicate that in addition to the primary premixed flame, the stratified charge in a combustor causes the formation of a diffusion flame. The diffusion flame is located between the primary premixed flame branches. The fuel is fully decomposed and converted to some intermediate species, like CO and H2, in the primary premixed flame branches. Due to the shortage of oxygen, the formed CO and H2 in the fuel rich region of the premixed flame branch is further transported to the downstream until they meet the oxygen from the fuel lean region. This leads to the formation of the diffusion flame. There is an interaction between the diffusion flame and the primary premixed flame branches. The interaction intensifies the burning speed of the primary premixed flame. Both the heat transfer and the diffusion of hydrogen and some radicals cause the interaction. With the increase of the stratified charge region, the diffusion flame zone is enlarged and the interaction is enhanced.
A Material Utilization Factor for Quantifying the Performance of Optimal Shape Extended Surfaces of Minimum Volume
Authors: Kobus Chris J.
Published: April 2008

Research has been undertaken here to determine a new fundamental parameter to judge the performance of optimally-shaped fins. Much research has been published on optimal shapes, but the gains have not been quantified explicitly versus even the constant cross-sectional area fin. Implicitly, optimum fins use less material to achieve the same or similar performance to that of the standard pin fin. But what performance is comparative? Thermal energy dissipation, fin effectiveness and fin efficiency are a few examples. As will be shown in this paper, a material utilization factor will be defined and the performance of an optimally shaped fin will be quantified with that of the standard pin fin for a variety of design conditions.
Solidification and Epitaxial Re-Growth in Surface Nanostructuring With Laser-Assisted Scanning Tunneling Microscope
Authors: Wang Xinwei , Lu Yongfeng
Published: April 2008

In this work, parallel molecular dynamics simulation is conducted to study the long-time (up to 2 ns) behavior of argon crystal in surface-nanostructuring with laser-assisted STM. A large system consisting of more than one hundred million atoms is explored. The study is focused on the solidification procedure after laser irradiation, which is driven by heat conduction in the material. Epitaxial re-growth is observed in the solidification. Atomic dislocation due to thermal strain-induced structural damages is observed as well in the epitaxial re-growth. During solidification, the liquid is featured with decaying normal compressive stresses and negligible shear stresses. Two functions are designed to capture the structure and distinguish the solid and liquid regions. These functions work well in terms of reflecting the crystallinity of the material and identifying the atomic dislocations. The study of the movement of the solid-liquid interface reveals an accelerating velocity in the order of 3~5 m/s. The spatial distribution of the solid-liquid interface velocity indicates a non-uniform epitaxial re-growth in space. The bottom of the liquid solidifies slower than that at the edge.
A Method to Extract Interface Stress Intensity Factors Using Interlayers
Authors: Santhanam Sridhar
Published: April 2008

A method is presented here to extract stress intensity factors for interface cracks in plane bimaterial fracture problems. The method relies on considering a companion problem wherein a very thin elastic interlayer is artificially inserted between the two material regions of the original bimaterial problem. The crack in the companion problem is located in the middle of the interlayer with its tip located within the homogeneous interlayer material. When the thickness of the interlayer is small compared with the other length scales of the problem, a universal relation can be established between the actual interface stress intensity factors at the crack tip for the original problem and the mode I and II stress intensity factors associated with the companion problem. The universal relation is determined by formulating and solving a boundary value problem. This universal relation now allows the determination of the stress intensity factors for a generic plane interface crack problem as follows. For a given interface crack problem, the companion problem is formulated and solved using the finite element method. Mode I and II stress intensity factors are obtained using the modified virtual crack closure method. The universal relation is next used to obtain the corresponding interface stress intensity factors for the original interface crack problem. An example problem involving a finite interface crack between two semi-infinite blocks is considered for which analytical solutions exist. It is shown that the method described above provides very acceptable results.