bluuebunny/crossref_metadata_2025 huggingface dataset:
Collaboration of Technical Editing Students With Mechanical Engineering Seniors in a Capstone Design Course
Authors: Lanier Clinton , Janna William S. , Hochstein John I.
Published: May 2009

An innovative capstone design course titled “Design of Fluid Thermal Systems,” involves groups of seniors working on various semester-long design projects. Groups are composed of 3 or 4 members that bid competitively on various projects. Once projects are awarded, freshmen enrolled in the “Introduction to Mechanical Engineering” course are assigned to work with the senior design teams. The senior teams (Engineering Consulting Companies) function like small consulting companies that employ co-operative education students; e.g., the freshmen. In Fall 2006, the Engineering Consulting Companies also worked with students enrolled in a Technical Editing (TE) course—“Writing and Editing in the Professions”—within the English Department. The TE students would be given reports or instructional manuals that the Mechanical Engineering (ME) students had to write as part of their capstone project, and the resulting editing of their documents would be done by these TE students. Subsequently, the ME students were given a survey and asked to comment on this experience. In addition, the TE students were also surveyed and asked to comment as well. It was concluded that the collaboration should continue for at least one more cycle, and that the TE students were more favorably inclined toward this collaboration than were the engineering students.
A Numerical Study on the Effect of CO Addition on Flame Temperature and NO Formation in Counterflow CH4/Air Diffusion Flames
Authors: Guo Hongsheng , Neill W. Stuart
Published: May 2009

A numerical study was carried out to understand the effect of carbon monoxide enrichment on flame temperature and NO formation in counterflow methane/air diffusion flames. Detailed chemistry and complex thermal and transport properties were employed. The results indicate that when carbon monoxide is added to the fuel, both flame temperature and NO formation rate are changed due to the variations in adiabatic flame temperature, fuel Lewis number and chemical reaction. The combination effects of three factors result in the different characteristics of flame temperature and NO formation at various strain rates, when carbon monoxide is added. At a low strain rate, the addition of carbon monoxide causes a monotonic decrease in flame temperature and peak NO concentration. However, NO emission index first slightly increases, and then decreases. When the value of strain rate is moderate, the addition of carbon monoxide has negligible effect on flame temperature and leads to a slight increase in both peak NO concentration and NO emission index, until the fraction of carbon monoxide reaches about 0.7. Then with a further increase in the fraction of added carbon monoxide, all three quantities quickly decrease. When strain rate is increased to a value close to the strain extinction limit of pure methane/air diffusion flame, the addition of carbon monoxide causes increase in flame temperature and NO formation rate, until a critical carbon monoxide fraction is reached. After the critical fraction, the further addition of carbon monoxide leads to decrease in both flame temperature and NO formation rate. The paper also analyzed the variation in the mechanism of NO formation, when carbon monoxide is added.
A New 9-DoF Mobile Robotic Device to Enhance the Capabilities of People With Disabilities
Authors: Alqasemi Redwan , Dubey Rajiv
Published: May 2009

A wheelchair-mounted robotic arm (WMRA) system was designed and built to meet the needs of mobility-impaired persons with limitations of upper extremities, and to exceed the capabilities of current devices of this type. The control of this 9-DoF system expands on the conventional control methods and combines the 7-DoF robotic arm control with the 2-DoF power wheelchair control. The 3-degrees of redundancy are optimized to effectively perform activities of daily living (ADLs) and overcome singularities, joint limits and some workspace limitations. The control system is designed for teleoperated or autonomous coordinated Cartesian control, and it offers expandability for future research, such as voice or sip and puff control operations and sensor assist functions.
Position Tracking Control of Miniature Low Pressure Water Hydraulic Cylinders
Authors: Sindrey Russell , Bone Gary M.
Published: May 2009

Over the past 20 years research in the field of miniature actuators has increased substantially thanks to advances in smart material fabrication, semi-conductor chip technology and computer processing capability. Hydraulic cylinders offer many potential benefits as miniature actuators including: high power-to-weight ratio, mechanical stiffness, smooth motion and the potential for high positional accuracy. Despite their benefits the control of hydraulic cylinders with bore diameters under 10 mm has not been previously studied. The most significant obstacle to implementing the use of miniature cylinders is the unavailability of off-the-shelf proportional valves that are compatible with hydraulic fluid and precise enough for the position control task. In this paper two nonlinear control strategies are presented for the position control of two 4 mm bore diameter cylinders. Four off-the-shelf, low cost, 2/2 on-off miniature solenoid valves were used to control the flow of water to and from the cylinder chambers. A novel valve modeling technique is also presented, which allowed the on-off valves to approximate the behaviour of proportional solenoid valves, increasing their control capability. The tracking performance of each controller was experimentally tested and both controllers were found to achieve steady state positioning accuracies within ± 0.07 mm. The robustness of the controllers to changes in payload mass and vertical orientation were also tested. Results from several experiments are presented and compared.
Study on Deformation Behavior of the Buried Pipes for Cables of Electricity at Ground Subsidence
Authors: Shishikura Hiroshi , Naoi Hisashi , Okada Hideki , Osaku Makoto
Published: May 2009

In this study, we have an object to investigate the piping system buried in the ground at ground subsidence. Therefore, we conduct bending test of bellows pipes for buried piping using experimental equipment which is simulator for assumed ground subsidence. Grade of bellows pipe is stainless steel. We measure load and displacement and calculated stress and strain appeared at bellows pipe. We conduct bending test at four kinds of experiment conditions for outer surface of bellows pipe, that conditions are non-restraint, soil or gypsum are filled around outer surface of bellows pipe, buried piping system is set in the box in which soil is filled. By analyzing these experimental results, we clarify deformation characteristic of bellows pipes for buried piping at ground subsidence, and we verify the application of bellows pipe to buried piping.
Dealing With Biped Locomotion as a Dynamic Object Manipulation Problem: Manipulating of Body Using Legs
Authors: Beigzadeh Borhan , Meghdari Ali , Beigzadeh Yasan
Published: May 2009

In this paper, we try to show that it is possible to deal with biped locomotion as a dynamic object manipulation problem. We show that during locomotion, a biped locomotion can be seen as manipulating of upper part of biped robot using a leg, which now plays the role of a manipulator. So the whole locomotion process can be seen as a dynamic manipulation of an object (upper part of a biped robot) using a numerous series of manipulators each of which placed in a proper place where the object tends to land, so it catches the object and throws it to the next point which another manipulator waits for catching it. The authors in the previous works have explored the problem of dynamic manipulation of parts. The results have been validated with the aid of simulation.
Design and Control of the Planar Bipedal Robot ERNIE
Authors: Yang T. , Westervelt E. R. , Schmiedeler J. P. , Bockbrader R. A.
Published: May 2009

This paper presents the development of the planar bipedal robot ERNIE. ERNIE has 5 links: a torso, two femurs and two tibias without feet. ERNIE was designed and constructed to serve as a testbed for the development of novel control strategies for bipedal walking. A boom provides frontal plane stability, restricting walking motions to the sagittal plane, and ERNIE is configured to walk on a treadmill so that it can walk indefinitely in a confined space. ERNIE’s legs are modular so that morphological asymmetries and the use of feet may be explored more in future studies. Springs can be attached across the knee joints in parallel with the knee actuators to enable gaits that are more energetically efficient. ERNIE is currently controlled using the hybrid zero dynamics framework in which a function of the robot’s configuration that monotonically increases over a step is used to parameterize holonomic constraints on the robot’s motion. The constraints are designed via parameter optimization to minimize an objective function, such as the energy consumed over a step, and, at the same time, ensure gait stability. The constraints are enforced using decoupled high-gain PD control.
FEM Stress Analysis and Strength of Scarf Adhesive Joints of Similar Adherend Subjected to Impact Tensile Loadings
Authors: Sawa Toshiyuki , Hirayama Yuya , Dan He
Published: May 2009

The stress wave propagation and stress distribution in scarf adhesive joints have been analyzed using three-dimensional finite element method (FEM). The FEM code employed was LS-DYNA. An impact tensile loading was applied to the joint by dropping a weight. The effect of the scarf angle, Young’s modulus of the adhesive and adhesive thickness on the stress wave propagations and stress distributions at the interfaces have been examined. As the results, it was found that the point where the maximum principal stress becomes maximum changes between 52 degree and 60 degree under impact tensile loadings. The maximum value of the maximum principal stress increases as scarf angle decreases, Young’s modulus of the adhesive increases and adhesive thickness increases. In addition, Experiments to measure the strains and joint strengths were compared with the calculated results. The calculated results were in fairly good agreements with the experimental results.
Hail Effects on Air-Conditioner Performance
Authors: Sitzmann Matthew J. , Lu Frank K. , Smith Steve R.
Published: May 2009

Experiments demonstrated the effects on air-conditioner system performance resulting from dents in fins of their condenser coils and the extent to which conventional fin repair methods restore performance. Two different, commercially available, split-system, residential-type air-conditioners were tested. Flattening substantial areas of the fins caused a reduction in capacity and efficiency of the cooling systems tested. Performance first dropped appreciably when 60% of the fin areas were pressed flat. Incremental increases in total percentages of areas flattened beyond the first reduction in performance resulted in incremental decreases in capacity and efficiency. Specifically, with 60% of the fin area flattened on one condenser, system capacity decreased 4%; system SEER (efficiency), 9%. With 100% of the fin area flattened, system capacity decreased 27%; system SEER, 34%. Combing dents from the fins after the extreme case where all fins were flattened restored capacity to within 1% of the undented condition and SEER to within 6% of the undented efficiency. Similar results were obtained for the second condenser tested.
Characterization of Titanium Nitride Films Prepared by DC Reactive Magnetron Sputtering at Different Deposition Time
Authors: Yang Kai , Jiang Jianqing , Gu Mingyuan
Published: May 2009

Titanium nitride (TiN) films were grown on Si (111) and 95W18Cr4V high-speed steel substrates using DC reactive magnetron sputtering technique with different deposition time. The changes in crystal growth orientation of the TiN films were measured by X-ray diffraction (XRD). The surface & cross-sectional morphologies of TiN films were analyzed using field emission scanning electron microscopy (FESEM). The hardness and adhesive property of TiN films were evaluated as well. It is found that the increase of the film thickness favors the formation of the {111} preferred orientation of TiN films. When the {111} preferred orientation is presented, TiN films exhibit a kind of surface morphology of triangular pyramid with right angles. With the increase of the film thickness, the columnar grains continuously grow lengthwise and breadthwise. The size of grains influences the hardness of TiN films more greatly. The adhesive property of the film/substrate interface decreased with increasing film thickness.
Flow Pattern and Friction Coefficient of Water/Nonadecane-Particle Mixture Flow in Horizontal and Vertical Pipes
Authors: Hasegawa Hiroya , Ono Makoto , Hishida Makoto , Tanaka Gaku
Published: May 2009

Cold heat storage utilizing night-time electricity is one of the relevant technologies for the electric load leveling. Latent heat storage system with a large number of small paraffin particles is one of the promising technologies for the cold heat storage system. Small paraffin particles are generated by nozzle injection of liquid paraffin into cold water. Direct heat transfer between the ascending particles and surrounding cold water enhances the storage of latent heat in a short time. Transportation of solid paraffin particles suspended in water should be the best way to transport cold heat, because the density of cold heat stored in water/paraffin-particle mixture is very high. The present paper aims at investigating flow patterns and pressure loss of water/nonadecane-particle mixture flowing in horizontal and vertical pipes. The inner diameter and the average diameter of the nonadecane particle were 20mm and 3.7mm, respectively. Reynolds number, Froude number and volumetric concentration of nonadecane particles were varied in the ranges of 5000 ≤ Re ≤ 80000, 1 ≤ Fr ≤ 260 and 0.02 ≤ Cv ≤ 0.25. We found the following main results: (1) Four flow patterns were observed in the horizontal flow, (a) flow with a stationary particle bed, (b) flow with a sliding particle layer (c) heterogeneous suspension flow and (d) homogeneous suspension flow. The flow pattern shifted from (a) to (d) with increasing Reynolds number. (2) Homogeneous suspension flow was observed in the vertical up-flow. (3) Homogeneous and heterogeneous suspension flow was observed in the vertical down-flow. (4) The pressure loss coefficients λ of the horizontal flow were correlated by a function of λ and Re (λ = 0.479 Re−0.311) for the heterogeneous and homogeneous suspension flows (Re ≥ about 25000) and by a function of the excess pressure loss coefficient Φ, Fr and Cv (φ/Cv0.58 = 72.4Fr−1.25) for the flow with a sliding particle layer (Re ≤ about 20000). (5) The pressure loss coefficients of the vertical up-flow were correlated by a function of λ and Re (λ = 4.45 Re−0.501) in a large Reynolds number range of Re ≥ about 40000 and by a function of Φ, Fr and Cv (φ/Cv0.47 = 282Fr−1.47) in a small Reynolds number range of Re ≤ about 40000. (6) The pressure loss coefficients of the vertical down-flow were correlated by a function of Φ and Fr (φ = 73.0Fr−0.765).
Droplet Formation Under the Effect of a Flexible Nozzle Plate
Authors: Sangplung S. , Liburdy J. A.
Published: May 2009

Droplet formation from a flexible nozzle plate driven by a prescribed-waveform excitation of a piezoelectric is numerically investigated using a computational fluid dynamics (CFD) model with the VOF method. The droplet generator with a flexible nozzle plate, which is free to vibrate due to the pressure acting on the plate, is modeled in a CFD computational domain. The CFD analysis includes the fluid-structure interaction between fluid and a flexible plate using large deflection theory. The problem is characterized by the nondimensional variables based on the capillary parameters of time, velocity, and pressure. The CFD model is validated with the experiment results. This study examines the characteristics of the applied waveforms and nozzle plate material properties to change the vibrational characteristics of the nozzle plate. The effect of fluid properties on the droplet formation process is also investigated focusing on surface tension and viscous forces. The mechanism of the droplet formation excited by a drop-on-demand piezoelectric waveform is investigated using a step-function and a pulse waveform. The piezoelectric displacement plays an important role in generating either forward-driven momentum or a suction pressure inside the chamber. For the step-function waveform, the nondimensional applied impulse is defined and used to characterize the post-breakoff droplet volume. Increasing the impulse of the piezoelectric can be used to cause a faster droplet velocity and it is shown that the vibration of the nozzle plate has a strong effect on the droplet velocity, shape, and volume. Surface tension has strong influence to the droplet formation characteristics which is contrast to a viscous force that makes no difference on the droplet formation for different viscosities. For the combination of a fluid with high surface tension and the most flexible nozzle plate, this system can not cause the droplet ejected out of the nozzle.
Liquid and Gas Phase Velocity Measurements for Two Phase Flow in a Branching Microchannel Network
Authors: Kwak Younghoon , Pence Deborah , Liburdy James , Narayanan Vinod
Published: May 2009

This is a work in progress. The objective of the present work is to develop techniques for assessing velocity deficits in branching microchannel networks. Liquid velocity distributions were acquired using μPIV in gas-liquid flows through the initial branch in a fractal-like branching microchannel flow network. Gas interface velocities were determined along the centerline of the channel. The flow rate of air and water were 0.0016 g/min and 20 g/min, respectively. The primary observed flow regime was elongated bubbles. Experimental liquid velocities well matched the 0.20 m/s superficial liquid velocity. Experimental interface velocities were approximately an order of magnitude higher than the superficial gas velocity of 0.01 m/s. Velocity deficits based on measurements are on the order of 0.065 m/s. Using interfacial velocities at the channel centerline, the trailing edge velocity was observed to be 15% percent faster, on average, than the leading edge velocity. This could be attributed to bubbles expanding into the bifurcation. Twenty percent standard deviations in average interface velocities were attributed to insufficient samples as well as projected to be a consequence of changing shape of the interface between consecutive image pairs. Changes in bubble shape may also be responsible for the observed differences between leading and trailing edge velocities.
A Bending Beam-Based Path Planning Method Suitable for Mobile Robots in Sensor Network Environments
Authors: Zhou Yu
Published: May 2009

This paper introduces a novel distributive path planning method, the bending beam method, for mobile robots moving in environments monitored by wireless sensor networks. The proposed method is inspired by the deflection analysis of bending beams. The initial and goal positions of a mobile robot are connected by a virtual beam. The in-between obstacles are replaced with the effective loads acting on the beam. The resulting robot path is represented by the deflection curve of the beam under those loads. Following the principle of superposition, the beam deflection under all the loads is equal to the sum of the deflections caused by the individual loads acting on the beam separately. In an environment covered by a wireless sensor network, each sensor node monitors the obstacles (stationary and moving) in its neighborhood. By letting each sensor node compute the deflections of the virtual beam caused by only those neighboring obstacles, the computation load for the global robot path planning can be distributed among the sensor nodes. Thus, the path planning becomes a highly parallel computation procedure. The robot only needs to collect the results from the sensor nodes and sum them up to generate its path. Moreover, the robot path can be dynamically modified by the sensor nodes in the case of moving obstacles. As a result, the proposed method may substantially reduce the time complexity of the sensor-based motion planning for mobile robots in dynamic environments, with the assistance from sensor networks.
Research on Deep-Sea Electric Power Generation Technique From Seawater Pressure
Authors: Wang Feng , Gu Linyi , Cao Jianwei , Chen Ying
Published: May 2009

A novel seawater pressure energy conversion system that utilizes seawater pressure to generate electric energy has been studied in this paper. The energy conversion system utilizes the pressure difference between the pressurized seawater and the empty pressure container to drive hydraulic motor and the coaxially coupled generator to generate electric energy. The output electric energy has been recorded by the data logger throughout the process. However, the actual conversion efficiency from seawater pressure energy to electric energy reaches only 63.8%. Moreover, the electric power supply time of the conversion system has mainly been limited by the holding capacity of the empty pressure container. The low conversion efficiency and the short electric power supply time have limited its application in the long-term in-situ observatory stations. Therefore, a new hydraulic driving system consisting of high-speed on/off valves will be applied to the system not only to improve the conversion efficiency but also to extend the electric power supply time. In the new hydraulic driving system, the input flow rate of the system has been largely reduced due to the recycle of the flow through the hydraulic motor. Thus the conversion efficiency has been improved and the electric power supply time has been extended. In the current study, the analysis is conducted at various duty ratios of PWM (Pulse Width Modulation) signal which is provided to highspeed on/off valves so as to obtain maximum conversion efficiency. Research shows the optimum duty ratio and the maximum conversion efficiency at the optimum duty ratio can be theoretically calculated when the properties of the system are known. Simulation results have demonstrated the influence of duty ratio on conversion efficiency. Although the conversion efficiency of the system with the new hydraulic driving system has not increased significantly, the reduction of the input flow rate has largely extended the electric power supply time which is very useful for long-term in-situ observatory stations.
Bayesian Military Impulse Noise Classifier
Authors: Bucci Brian , Vipperman Jeffrey , El-Jaroudi Amro
Published: May 2009

Civilian noise complaints and damage claims have created the need for stations to monitor military impulse noise. However, the stations currently in service suffer from numerous false positive detections (due to wind noise) of impulse events and often miss many events of interest. To improve the accuracy of military impulse noise monitoring, an algorithm based upon a Bayesian classifier with inputs of conventional and custom acoustic metrics is proposed. To train and evaluate the noise classifier approximately 1,000 waveforms were field collected. The final Bayesian noise classifier used kurtosis and crest factor and, the frequency domain metrics, spectral slope and weighted square error as inputs. The EM algorithm is utilized to fit multi-Gaussian distributions to the different classes of data. In testing the classifier performed to accuracies of up to 99.6%.
Boundary-Induced Vibrational Spectra Broadening in Nanostructures
Authors: Ruan Xiulin , Bao Hua , Kaviany Massoud
Published: May 2009

Vibrational spectra are calculated and analyzed for nanostructures (including thin films, nanowires, and quantum dots) of yttria, an important laser host material. Lattice dynamics results show that vibrational spectra of nanocrystals are distinct from that of the bulk crystal, in the extended tails at low and high frequencies. This broadening of vibrational spectra is found to be resulted from the broadening of atomic spring constants at both surface and interior, especially at the surface. Molecular dynamics simulations are employed to further decompose the contributions of the surface and internal atoms, respectively. The results show explicitly that the surface spectra have evident tails and the interior spectra have moderate tails, confirming the results of lattice dynamics calculations.
Package Tilt Prediction Using Surface Evolver
Authors: Hornales Benjie B. , Almagro Erwin Ian V.
Published: May 2009

In board level package mounting process, many parameters will influence the final joint shape including the package stand-off height. If the stand-off height of solder joints at opposite ends does not equal, package tilting will occur. As a proactive measure to ascertain no tilting issues for newly develop packages, a methodology of predicting package tilting for BGA is developed using an energybased simulation model with surface evolver. The solder joint prediction model developed by Brakke proved to be very useful in predicting solder joint geometry after reflow and it will also be used to predict package tilting for BGA during board level mounting. This paper will discuss the capability of Surface Evolver in predicting solder joint geometry like solder ball height and diameter, and solder joint height. Then it moves on to discuss the methodology in using the same tool in predicting package tilting in board mounting process. It will be shown that the result of the surface evolver is well within the experimental data. Surface evolver program requires a command line input programming which is not very user-friendly, so a user interface was created using Visual Basic® 6 so that the engineer will only need to input relevant parameters into the program and command encoding is done automatically.
Thermal and Mechanical Analysis of High Power LEDs With Ceramic Packages
Authors: Hu Jianzheng , Yang Lianqiao , Shin Moo Whan
Published: May 2009

In this paper we present the thermal and mechanical analysis of high power light emitting diodes with ceramic packages. Transient thermal measurements and thermomechanical simulations were performed to study the thermal and mechanical characteristics of ceramic packages. Thermal resistances from the junction to the ambient were decreased from 76.1 °C/W to 45.3 °C/W by replacing the plastic mould to the ceramic mould for LED packages. Higher level of thermomechanical stress in the chip was found for LEDs with ceramic packages despite of less mismatching coefficients of thermal expansion comparing with plastic packages. The results suggest that the thermal performance of LEDs can be improved by using ceramic packages, but the mounting process of the high power LEDs with ceramic packages is critically important and should be in charge of delaminating interface layers in the packages.
Influences of Magnetic Particle-Particle Interactions on Orientational Distributions and Rheological Properties of a Semi-Dense Colloidal Dispersion Composed of Rod-Like Hematite Particles: Analysis by Means of Mean Field Approximation for an External Magnetic Field Parallel to the Angular Velocity Vector of a Simple Shear Flow
Authors: Hayasaka Ryo , Aoshima Masayuki , Suzuki Toshinori , Satoh Akira
Published: May 2009

We have investigated mainly the influences of magnetic particle-particle interactions on orientational distributions and viscosity of a semi-dense dispersion, which is composed of rod-like particles with a magnetic moment magnetized normal to the particle axis. In addition, the influences of the magnetic field strength, shear rate, and random forces on the orientational distribution and rheological properties have been clarified. The mean field approximation has been applied to take into account magnetic interactions between rod-like particles. The basic equation of the orientational distribution function has been derived from the balance of torques and solved by the numerical analysis method. The results obtained here are summarized as follows. For a strong magnetic field, the rotational motion of the rod-like particle is restricted in a plane normal to the shearing plane because the magnetic moment of the particle is restricted in the magnetic field direction. Under circumstances of a very strong magnetic interaction between particles, the magnetic moment is strongly restricted in the magnetic field direction, so that the particle has a tendency to incline in the flow direction with the magnetic moment pointing to the magnetic field direction. For a strong shear flow, a directional characteristic of rod-like particles is enhanced, and this leads to a more significant one-peak-type distribution of the orientational distribution function. Magnetic interactions between particles do not contribute to the viscosity because the mean-field vector has only a component along the magnetic field direction.
Analysis of Reversal Behavior for an Automobile Wiper Blade
Authors: Takebe Yuki , Yoshizawa Masatsugu , Akuto Tuneo , Yoda Takeshi , Kamiyama Katuya
Published: May 2009

The development of a numerical simulation has been demanded for improving the automobile wiper systems from the industrial viewpoints. It is widely known that, however, vibrations caused by the wiping motion cause a trouble of wiping. Several studies have been carried out to investigate the dynamic behavior of the wiper systems. However, the phenomena have not yet been theoretically analyzed. The purpose of this research is to develop a numerical simulation of the reversal behavior of a wiper blade. To begin with, the experiment was conducted with the real wiper systems to observe the reversal behavior of the wiper blade. After observing its motion, an analytical model was developed to essentially characterize the wiper systems. The model is composed of a multi-degree-of-freedom spring-mass system with restraint conditions to ensure the contact between a blade and a wind-shield at all time. The dynamic motion and the mechanism of the reversal behavior of the wiper blade were investigated by using nonlinear equations. Furthermore, the above phenomena were discussed using the nonlinear equations of the vibration of the wiper blade from the viewpoint of the nonlinear dynamics.
High Reliability and Thermal Performance FCBGA Package
Authors: Hung Gino , Tsai Ho-Yi , Huang Chun An , Chiu Steve , Hsiao C. S.
Published: May 2009

A high reliability and high thermal performance molding flip chip ball grid arrays structure which was improved from Terminator FCBGA®. (The structure are shown as Fig. 1) It has many advantages, like better coplanarity, high through put (multi pes for each shut of molding process), low stress, and high thermal performance. In conventional flip chip structure, underfill dispenses and cure processes are a bottleneck due to low through put (dispensing unit by unit). For the high performance demand, large package/die size with more integrated functions needs to meet reliability criteria. Low k dielectric material, lead free bump especially and the package coplanarity are also challenges for package development. Besides, thermal performance is also a key concern with high power device. From simulation and reliability data, this new structure can provide strong bump protection and reach high reliability performance and can be applied for low-K chip and all kind of bump composition such as tin-lead, high lead, and lead free. Comparing to original Terminator FCBGA®, this structure has better thermal performance because the thermal adhesive was added between die and heat spreader instead of epoxy molding compound (EMC). The thermal adhesive has much better thermal conductivity than EMC. Furthermore, this paper also describes the process and reliability validation result.
Dedicated Workshops to Educate T-Shaped Engineers
Authors: Gerson Ph. M. , Taylor A. J. , Ramond B.
Published: May 2009

Technical Innovation covers the process of creating a new successful competitive product from invention to production and market introduction within a practical company related context. Typically education for this kind of complicated, open ended work requires mastering a wide range of knowledge-areas and a lot of hands-on training practice in projects and workshops. The combination of depth and width is symbolized by the “T-shape”. Well-known learning theories give a good rationale of the teaching approaches that were developed over the years and a confirmation of this approach, including the important role of the experienced tutor, is found in the study of excellent companies. Work of a “T-shaped” engineer in the technical innovation process bears many similarities to the ideal transformation process of a company, like Collins describes in his “Good to Great”. The processes have a very comparable open-ended character, a focus for essence and simple, elegant solutions, opportunities and inventions. Success seems to rely more on the right people and a concentrated shared-goal driven cooperation (“flow”), than on the right methods of work. Collins’ observations and conclusions, applied to the domain of engineering design education helps understanding the earlier reported 15 years success of the International Product Design Engineering (IPDE) course of the Hanze University Groningen, with its combination of lecturing, projects and workshops, with a high reality content and direct supervision. The IPDE-related “Open Dynamic Design” (ODD) project and the educational experiments showed similar observations. Essential is the committed experienced participation in real innovation projects and intensive workshops, lead by very experienced T-shaped supervisors/“masters”, having deep knowledge over a good part of technologies, entrepreneurial and/or design related issues and good understanding of interrelationship and consequences in the other fields. They also should have a track record on the methodologies of product innovation and product development. Like the Collins level-5 leaders, they should be able to be both creative and analytical, give the students freedom and control them at the appropriate moments. They power the theoretical most effective learning “circle” with focused introductions and assignments, their direct, knowledgeable and adequate feedback, and quiet help during contemplation. Then the workshops are really fun and effective. The Loughborough and Glasgow Design engineering courses, the new master course at the Innovation Centre of the University of Technology of Compiegne (UTC) and the one at the Hanze Institute for Technology — an upgrade from IPDE — are built on these insights. To safeguard the continuation of this approach, a pool of experienced and potential (home and guest) T-experts is founded together by the small group of universities and their industrial partners, working jointly in the workshops, projects and modules, training the trainers while training the students - in T-design.
Development and Evaluation of a Urethane Jacketed Tail Roller for Continuous Mining Machines
Authors: Smith Adam K. , Yantek David S. , Peterson J. Shawn
Published: May 2009

Occupational noise-induced hearing loss continues to be one of the most pervasive health problems in the mining industry, despite over 25 years of regulation. One of the loudest pieces of equipment used in underground mining is the continuous mining machine. Noise sample data collected by the Mine Safety and Health Administration indicate that 42% of noise overexposures between 2000 and 2005 involved continuous mining machine operators. Previously conducted field and laboratory tests have determined that the continuous mining machine conveyor system is a dominant noise source. Loud impacts occur as the conveyor chain flight bars, used to move the mined aggregate, traverse their path from the top to the underside of the conveyor deck. Various noise control treatments have been applied to abate noise caused by the conveyor system. A durable polyurethane coating has been developed for the conveyor flight bars, resulting in a time-weighted average reduction of 3 dB(A) for an eight-hour work shift. In an attempt to further reduce continuous mining machine operator overexposures, a similar urethane coating has been applied to the tail roller component of the conveyor system. Laboratory results showed a 2 dB(A) reduction in sound power levels, but the component failed during underground durability testing. An outer steel sleeve has been added to the urethane coating of the tail roller to enhance wear resistance during mining. The urethane jacketed tail roller is the latest effort, combined with previous noise treatments, to bring the continuous mining machine into compliance with federal noise regulations.
Modelling of Manufacturing Processes by FEA-Method for the Production of Natural Fiber-Reinforced Plastics
Authors: Doersch Christian , Muessig Joerg , Mueller Dieter H.
Published: May 2009

In recent years a growing demand for natural fiber-reinforced plastic components and structures has been observed. One important area of application is transportation, particularly in the automotive industry. Due to market demand, innovative process technologies for fast, cost-effective and quality-driven manufacture of natural fiber-reinforced plastic components is required. This paper will focus on the development of technologies for automised manufacturing of NFRP-components with resin infusion processes. At present NFRP-components are manufactured automatically but without flexibility concerning the deviations of material properties or part geometries. This lack of control in manufacturing results in long cycle times, low process control and high costs. The Bremen Institute for Engineering Design (BIK) is developing and improving machine and process technologies for automised textile handling. The handling system has to meet the requirements of large, limp textile material. The authors have mutually developed methods for the simplified simulation of textiles. The simulation supports the evaluation of textiles and handling devices concerning the ability for better control in manufacturing. To meet these requirements, a simulation of the textile material with the “Finite Element Analysis” method supports the part and process design by reducing developing time and costs. For this purpose, the authors showed a simplified model with a reduced set of material data which is required for the FEA-model.
Acoustic Properties of Fluidlike Metamaterials Based on Sonic Crystals
Authors: Torrent Daniel , Sa´nchez-Dehesa Jose´
Published: May 2009

A homogenization method is used to get the effective parameters of two-dimensional clusters of solid cylinders embedded in a non viscous fluid or gas. The full elasticity is employed to describe the properties of cylinders. Asymptotic relations are derived and employed to formulate a method of homogenization based on the scattering properties of the cluster. Exact formulas for the effective parameters (i.e., effective sound velocity and effective density) are obtained as a function of the location of each cylinder, its physical parameters, and the embedded medium. Results of several solid-fluid composites will be reported. Also, phase-diagrams of fluid-like metamaterials based on sonic crystal will be analyzed. It is concluded that the method provides a tool to design acoustic metamaterials with prefixed refractive properties. The long wavelength behavior (homogenization) of two dimensional sonic crystals (periodic arrangements of two dimensional sound scatters) has been widely studied in the last years [1–9] due to its possible use as refractive acoustic devices. In a previous paper [2] the authors develop a theory to obtain the effective acoustic parameters of a cluster of fluid cylinder embedded in a non viscous fluid or gas, both for ordered and disordered case. The application of this theory to solid cylinder-fluid medium is only possible when the cylinder is rigid, that is, the sound does not propagates inside the cylinder. When it happens, elasticity must be taken into account, and a solid cylinder, in principle, cannot be considered a fluid cylinder with similar parameters. Here, the theory will be completed for the case of an elastic cylinder, and it will be discussed under what conditions an elastic cylinder can be considered a fluid cylinder, and which ones are the acoustic parameters of this fluid cylinder. It will be shown also that the effective parameters of clusters of elastic cylinders can lead to an effective medium with an effective speed of sound both higher and lower than that of the surrounding medium, and a phase diagram to analyze and predict this behavior will be given. Finally, a method to obtain a relative acoustic impedance equal to one (zero surface reflectance) will be discussed, and also a phase diagram to obtain it will be given.
Sound From Flow Over a Rough Surface
Authors: Anderson Jason , Stewart Devin , Goody Michael , Zoccola Paul
Published: May 2009

The mechanism for sound production from flow over a rough surface is not well understood. Measurements of radiated noise and low-wavenumber unsteady surface pressures were carried out in order to better understand the sound production mechanism. The initial results of an ongoing experimental investigation of the sound produced by flow over a rough surface are presented. In order to investigate scaling relationships, the flow speed, roughness height, and roughness element distribution were varied. Previous investigations have reported roughness noise levels that scale on flow velocity, roughness height, and fetch area and have indicated that the sound production may be dipole or quadrupole in nature. Prevailing analytical models assume that both types of sources are present. The scaling of roughness noise for large roughness height (k+ = uτk/ν of order 1000) has not been investigated previously and is part of the current study. The scaling behavior of low-wavenumber surface pressures is discussed, in addition to the comparison of radiated noise spectra obtained by phased microphone array measurements.
Technical and Economical Analysis of a Micro-CHP Facility Based on Dynamic Simulation: A Case Study
Authors: Cho Heejin , Luck Rogelio , Chamra Louay M.
Published: May 2009

Combined Heating and Power (CHP) generation systems have been widely recognized as a key alternative for heat and electricity generation due to their outstanding energy efficiency, reduced emissions, and relative independence from centralized power grids. Similar to CHP systems, micro-CHP (micro-Cooling, Heating, and Power) systems consist of power cogeneration systems and thermally-activated components such as absorption chillers, water tanks, boilers and air handling units. There have been many studies in regard to steady-state models following load profiles in order to demonstrate the economic advantage of CHP systems. However, there has not been much work using dynamic simulation of CHP systems, which include the transient response of the building along with the rest of the CHP components. This paper presents both technical and economical results from the dynamic simulation of the micro-CHP system used to model the test facility at Mississippi State University (MSU). The results are compared to a dynamic model using a conventional heating and cooling system. TRNSYS, a dynamic simulation program, is used to simulate the time response of the micro-CHP system based on the transient heating, cooling, and electric power demand of a test facility. The performance and costs of a conventional heating and cooling system are assessed using TRNSYS and the results are then compared against the simulated performance of the micro-CHP system. Details of the simulation model include geometric and material information (e.g., size and type of walls and windows), internal gains (following the equipment and occupancy schedules), local weather information (e.g., ambient temperature, relative humidity, and solar radiation), and estimated infiltration of the test facility.
Atomistic Mechanism of Ion Beam Deposition Induced Curvature Formation in Thin-Films
Authors: Terdalkar Sachin S. , Zhang Sulin , Rencis Joseph J.
Published: May 2009

Molecular dynamics (MD) simulations are performed to study the stress generation mechanisms in cantilever graphene sheets impacted by energetic carbon neutrals. The carbon-carbon interactions are described by the Tersoff-Brenner potential [1]. The MD simulations show that the free-end deflection of the graphene sheets is strongly dependent on the kinetic energy of the incident ions. At low incident energy (<<10eV), the free end bends towards to the side on which ions are deposited (upward deflection); at high incident energy, the free end bends away from the side on which the ions are deposited (downward deflection). The downward deflection reaches its maximum at around 50 eV, beyond which the downward deflection decreases with increasing incident energies. In addition, the evolution of the free-end deflection in terms of the number of deposited atoms is also dependent on the kinetic energy of the incident ions. These numerical observations suggest that intrinsic stress of different levels in the graphene sheets is generated. A close examination of the microstructures of the grown films indicates that the generated stress can be attributed to a competing mechanism of the production and annihilation of vacancy-like and interstitial-like defects in the films.
Carbon Nanopaper Sheets for Damping Applications: Processing and Characterization
Authors: Gou J. , Gu H. C. , Song G.
Published: May 2009

Carbon nanotubes and carbon nanofibers have been used as nanofillers for high performance damping composite materials in recent years. The large specific area (1000 m2/g) and aspect ratio (>1000) of carbon nanotubes and nanofibers promote significant interfacial friction between carbon nanotubes/nanofibers and the polymer matrix. The high stiffness and strength of carbon nanotubes and nanofibers enlarge the differences in the strains of individual constituents of the composites, which causes much higher energy dissipation in the polymer matrix. However, adding small amount of carbon nanotubes and nanofibers will significant increase the viscosity of polymer resin, which makes the dispersion and resin flow through the porous fiber mats extremely difficult. In addition, the fiber mats will filter carbon nanotubes and nanofibers during liquid molding process such as Resin Transfer Molding (RTM) and Vacuum-Assisted Resin Transfer Molding (VARTM). A unique concept of manufacturing nanocomposites with carbon nanotube/nanofiber based nanopaper sheets for structural damping applications has recently been explored. This approach involves making carbon nanopaper sheet by the filtration of well-dispersed carbon nanotubes and carbon nanofibers under controlled processing conditions. Subsequently, carbon nanopaper sheets are integrated into composite laminates using Vacuum Assisted Resin Transfer Molding (VARTM) process. In this study, several nanocomposite plates were fabricated with carbon nanopaper sheet as surface layer. For the comparative study, the regular composite plates without carbon nanopaper sheet were also fabricated. To identify the damping characteristics of each specimen, the Frequency Response Function (FRF) was estimated by a pair of piezoceramic patches: one as an actuator to excite the specimen and the other as a sensor to detect the induced vibrations. From the FRF, the damping ratio of the specimen at each modal frequency of interests was calculated. The experimental results clearly show a significant improvement of damping properties of nanocomposites plates. This research demonstrates structural damping enhancement via carbon nanopaper sheets and provided basic understanding of the damping characteristics for the optimal design and fabrication of high performance damping composites, which have the potential to be used as structural components for many applications.