bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of Supercritical Jet Fuel Injection
Authors: Rachedi R. R. , Crook L. , Sojka P. E.
Published: May 2009

An experimental investigation was conducted to examine the behavior of supercritical fluid (SCF) jets injected into supercritical environments. The behavior of the fluid, JP-10, was studied after it was passed through a pressure-swirl atomizer and entered a nitrogen environment. SCF jet behavior was characterized by the jet cone angle and penetration length. Cone angle and penetration length are reported as functions of density ratio (defined as the ratio of density of the injected fuel to the nitrogen environment), fuel mass flow rate, and pressure-swirl atomizer internal geometry. The density ratio was varied by altering the reduced temperature of the fuel (1.01<Tr<1.10) and nitrogen environment, while keeping the fuel reduced pressure constant at 1.05. Fuel mass flow rate ranged from 1.0 to 3.0 g/s (7.94 to 23.8 lbs/hr). Pressure-swirl atomizer internal geometry was varied by controlling the swirl number, ranging from straight bore to Sn=1.0. It was found that increasing the swirl number for a SCF fluid has the largest effect on jet cone angle, followed by a change in the density ratio; the mass flow rate had the least effect. The penetration length of the SCF jet increased when either the mass flow rate or density ratio increased. The mass concentration field significantly widens when the swirl number of the injector increased, as opposed to changes in the mass flow rate or density ratio which were found to have little effect.
The Effectiveness of the Quality Function Deployment in Managing Manufacturing and Transactional Processes
Authors: Gentili Enzo , Aggogeri Francesco , Mazzola Marco
Published: May 2009

The goal of Quality Engineering is to design quality into every product, service and manufacturing process. In particular a methodology is claimed to be very important for Quality design and management: Quality Function Deployment (QFD). QFD is a structured methodology and mathematical tool used to identify and quantify customer requirements and translate them into key critical parameters of systems and processes. The aim of the paper is to show how a quality management approach can support the increase of the process capability in a global vision of every business. QFD represents one of the most successful tools used in industrial management. By using actual and real cases, the paper shows the effectiveness of the QFD in improving both the management of a process and its capability. Four examples are presented. They take into account different environments: pharmaceutical, mechanical, healthcare and transportation markets. The first case study is deployed in a pharmaceutical company to satisfy the new customer requirements for the introduction of a nasal spray product on the Japanese market. The second example is applied to the automotive market for the production of air-cooling devices for deluxe vehicles. Finally, the other two cases show the implementation of the QFD tool in transactional processes, such as Cargo Center activities and healthcare services.
Visualization of Two-Phase Refrigerant and Refrigerant-Oil Flow in a Microchannel
Authors: Field Brandon S. , Hrnjak Pega
Published: May 2009

Visualizations of adiabatic two-phase refrigerant flow in a glass channel of diameter 0.5 mm have been made for three refrigerants: R134a, Propane (R290), and Ammonia (R717), representing a wide span of fluid properties, which covers most of the refrigerants commercially in use. In these visualizations four flow regimes were observed: bubble-slug, slug, slug-annular, and annular. These flow regimes were compared to various flow maps, including some developed for small channels. Flow visualizations were also made with mixtures of R134a and 68-weight POE oil at oil circulation rates of approximately 0.5, 1.5 and 3 percent. This is of interest when considering refrigeration systems, which have a small percentage of oil in circulation that travels through system and through the heat exchangers. When the refrigerant is in a liquid state, this presents little variation in fluid properties, because the concentration is so small. However, when the refrigerant is partly vapor, the oil concentration in the remaining liquid can have significant effect on the fluid properties. In addition, the saturation temperature and pressure of the oil-refrigerant mixture changes with concentration, where a single-phase vapor is never observed in flows of oil-refrigerant mixtures, even at temperatures exceeding the saturation temperature of the pure mixture. This effect is known as “apparent superheat”.
Liquid-Phase Sintering of ScSZ Electrolytes for Solid Oxide Fuel Cells
Authors: Xu Zhigang , Sankar Jag
Published: May 2009

Reducing the manufacturing cost is urgently desired to lower the overall cost of solid oxide fuel cells (SOFCs). High energy expense in the sintering of the fuel cell components, especially the stabilized zirconia electrolyte, is one of the major sources for the cost. Reduction of the sintering temperature will save the energy for sintering. In this paper, liquid-phase sintering of scandia-stabilized zirconia (ScSZ) was achieved at lower temperatures by addition of bismuth oxide will be presented. Different fractions bismuth oxide powders ranging from 0 to 8 wt% were added into ScSZ powders. The powder was compacted into thin pellets using a uniaxial press at a pressure of 200 MPa. The pellets were sintered at different temperatures from 950°C to 1450°C which were varied according to the level of bismuth oxide addition. The microstructure of the sintered specimens was examined with SEM, TEM and XRD.
Adaptive Dynamic Control of Nonlinear Systems With Actuator Amplitude and Rate Saturation Constraints
Authors: Leonessa Alexander , Haddad Wassim M. , Hayakawa Tomohisa , Morel Yannick
Published: May 2009

A direct adaptive nonlinear tracking control framework for multivariable nonlinear uncertain systems with actuator amplitude and rate saturation constraints is developed. To guarantee asymptotic stability of the closed-loop tracking error dynamics in the face of amplitude and rate saturation constraints, the control signal to a given reference (governor or supervisor) system is modified to effectively robustify the error dynamics to the saturation constraints. An illustrative numerical example is provided to demonstrate the efficacy of the proposed approach.
Rheological Study of Steady Shear and Linear Viscoelastic Characteristics of Polyethylene and Polycarbonate Nanocomposites
Authors: Lalko Michael P. , Rakesh Leela , Hirschi Stanley
Published: May 2009

The addition of nano-sized particles into a polymer matrix is an excellent way to manipulate polymer properties. Our current efforts try to understand how a material’s properties are influenced by parameters such as temperature, particle size, and particle concentrations of additives. This paper presents the rheological behavior of polycarbonate (PC) and low density polyethylene (LDPE) containing at least 2.5% and 5% weight fractions of functionalized and un-functionalized carbon nanotubes (CNTs). These materials were investigated using steady shear and oscillatory rheometry over a range of processing temperatures. The properties examined through rheological experimentation include: viscosity, critical strain, storage modulus (G′), and loss modulus (G ). The nanocomposites samples were examined using scanning electron microscopy (SEM) and UV light microscopy.
An Iterative Kalman Filter for a 3D Ultrasonic Position Estimation System
Authors: Chitikeshi Sanjeevi , Mahajan Ajay , Akers Jennifer
Published: May 2009

This paper describes an iterative Kalman Filter to increase the accuracy of a dynamic 3D position estimation system. The novelty of the system lies in the fact that a difference in the time of arrivals is used in conjunction with an estimated speed of sound within the system formulation, and the Kalman Filter is used to further increase the accuracy and robustness of the output. The output is a 3D position of the transmitter obtained from the difference in time of arrivals of the wave burst at multiple receivers fixed within an inertial frame. Results are provided to show the increase in accuracy and robustness along with some limitations of the system. The system has many applications the most significant being image guided surgery.
A Role of Unsupervised Clustering for Intelligent Fault Diagnosis
Authors: Datta A. , Mavroidis C. , Hosek M.
Published: May 2009

In the field of data analysis two terms frequently encountered are supervised and unsupervised methods of data classification and clustering methodologies. While supervised methods mostly deal with training classifiers for known symptoms, unsupervised clustering provides exploratory techniques for finding hidden patterns in the data. With huge volumes of data being generated from different systems everyday, what makes a system intelligent is its ability to analyze the data for efficient decision-making based on known or new cluster discovery. The three-fold contribution of this paper can be summarized as the role of unsupervised clustering for intelligent decision-making process, review of existing unsupervised models, including self-organizing maps (SOM), hierarchical tree (HT) model and quality adaptive threshold (QT) model, and lastly a new hybrid model for unsupervised clustering is proposed. For case study, we have taken the example of an intelligent decision making process in the field of fault diagnosis of industrial robots. The unsupervised models were tested on data obtained from an industrial robot used in the semiconductor industry. This paper presents the first set of results obtained from these four methods and discusses further applications of these methods.
An Analytical Method for Dielectrophoresis and Traveling Wave Dielectrophoresis Generated by an Interdigitated Parallel Electrode Array
Authors: Song Hongjun , Bennett Dawn J.
Published: May 2009

As a new technique, dielectrophoresis has been proven to be successful in the separation, transportation, entrapment and manipulation of cells, DNA molecules, and viruses. One typical design uses an array with interdigitated parallel electrodes to manipulate and separate particles using traveling wave and conventional dielectrophoresis. In order to obtain an analytical solution for the dielectrophoretic force or traveling wave dielectrophoretic force, the electric potential equation needs to be solved. Unfortunately, the mixed type of boundary condition (Dirichet and Neumann) for the electric potential equation poses a large challenge for obtaining an analytical solution. Although some analytical solutions have been achieved using an approximate single type of boundary condition instead of the exact boundary condition, this leads to inaccurate results especially in the zone near the electrodes which cannot be neglected. In this paper, we present an analytical method for solving the electric potential equation with the mixed type of boundary condition. We compare our analytical solution with the numerical results obtained using the Computational Fluid Dynamics Research Corporation, CFDRC, code which verifies our analytical method is correct for solving this problem. In addition, comparisons are made between the analytical solutions with approximate boundary conditions and those with exact boundary conditions. The comparison shows our analytical solution gives a more accurate analysis for the conventional and traveling wave dielectrophoretic forces.
On Designing for Enhanced Product Sustainability by Considering the Induced Residual Stresses in Machining Operations
Authors: Outeiro J. C. , Dillon O. W. , Jawahir I. S.
Published: May 2009

For improving product sustainability, a number of measures can be adopted during the product design stage for manufacturing. The modeling and control of the residual stresses and surface roughness generated by machining are among the major measures which have been shown to demonstrate the strongest influence on the machined component’s performance during its service life. The proper control of the residual stresses would provide increased product lifetime, reduced part distortion, reduced weight and reduced and less frequent maintenance and inspection of the product while maintaining the same safety level, or perhaps even improving it. This paper presents an analysis of the influence of machining parameters on the residual stresses generated in machining operations. This analysis was performed on several work materials, including carbon steels, stainless steels, Inconel alloys and tool steels. This allows developing a number of feasible means to control the residual stresses during manufacturing.
On Differences of Statically and Dynamically Determined Elastic Modules of Materials Like Trabecular Bone
Authors: Besdo D. H. , Besdo S.
Published: May 2009

The linear elastic material law which is usually applied in simulations of bone behavior reads σij = Cijkl εkl. It contains up to 21 independent constants. In most applications only nine constants (orthotropic behavior) are used. The determination of these constants is troublesome. The most applied experimental method is based on ultrasonic wave propagation. As it is often recognized the elastic modules measured by this method differ significantly from those found by static testing. Whereas Young’s modules differ slightly only, the determination of shear modules by ultrasonic methods is extremely doubtful, especially in trabecular bone. To find reasons for this effect, wave propagations are simulated by Finite-Element-techniques. This is done for artificial structures and also for realistic models of trabecular bone based one μCT-data. It can be recognized that in structured media always three types of waves propagate through the material with different speeds. Unfortunately the shear wave which is to be measured is the slowest one. Even if no longitudinal waves disturb the measurements, at least bending waves appear and pretend some kind of shear mode. The different orientations of the trabeculae can cause longitudinal waves when shear waves are applied. The stimulation of the ultrasound is at first simulated as a half cycle or as a step function only. The realistic waves are superimpositions of several of such motions. Such a relatively simple simulation makes possible to distinguish the three wave types mentioned above. The superimpositions complicate the motion extremely. Also reflection, damping and variable cross sections make it almost impossible to identify the modules, especially the shear modules, in a certain manner.
Wet Etched Pyramidal Microneedles With Fluid-Delivery Microchannels
Authors: Diehl Michael S. , Jensen Brian D.
Published: May 2009

A number of designs for microneedles have recently been developed to facilitate the painless injection of medications, such as insulin, into the human body [1–6]. The injections are painless because the needles penetrate the skin predominantly in the epidermal layer of skin which contains no nerve endings. Some microneedles do not contain inner channels and are simply coated with medication, the intent being that the transdermal drug delivery will take place through absorption over time. A more effective method of medicinal transfer is to equip the microneedles with an inner channel to facilitate rapid delivery of the medication to the skin.
Finite Element Modeling of Local Damage in Kevlar/Carbon Fiber Sandwich Under Low Velocity Impact
Authors: Jacque Saiphon , Rizza Robert , Mahinfalah Mohammad
Published: May 2009

Impact properties of carbon fiber and Kevlar or hybrid (3K carbon fiber/1500 Denier Kevlar) combination sandwich composite plates were numerically investigated in this study. The goal of this research was to define the change in impact properties as results of replacing the carbon fiber layer on the impact-side face sheet with combinations of carbon fiber/Kevlar or carbon fiber/hybrid. Information on impact energy and maximum impact force obtained from previous experiments were applied to validate the model input properties. The models were then used to characterize the mechanism of the reduction in the global stiffness of the sandwich plate due to the sequence of the damage in the foam core and the face sheet corresponding to the variation of the laminate mixture and loading energy. Results from this study could be of assistance to determining structure integrity with respect to the composite combination under impact load.
Flammability Resistance of Nanocomposite Foams
Authors: Ibeh Christopher C. , Bietto Stefano
Published: May 2009

The recent attention being given to blast mitigation research by government, industry and academia implies the need for flammability resistance studies of nanocomposite foams. Fire and smoke toxicity are typically associated with blasts, and some of the current designs for blast mitigation involve the use of nanocomposites and foams. The Center for Nanocomposites and Multifunctional Materials [CNCMM] employs a nanocomposite foam impregnated honeycomb as core for its energy dissipative designs. Preliminary results indicate that other than the enhancement of mechanical properties, well formulated nanocomposite foams provide improvement in flammability resistance. In this study, flammability resistance properties of syntactic nanocomposite foams are evaluated by cone calorimetry via such parameters as smoke density, mean heat release rate (MHRR), mass loss rate (MLR) and ignition time.
Engineering Education in the Age of Web 2.0: Explorations Through iMechanica.org
Authors: Li Teng , Suo Zhigang
Published: May 2009

Web 2.0 refers to a collection of second generation web services, such as blogs, social bookmarking, wikis, podcasts, and Really Simple Syndicates (RSS) feeds. While the first generation web (Web 1.0) is about linking information available online, Web 2.0 emphasizes online collaboration and sharing among people. These new web services bring up new opportunities to innovate how we conduct research and education. We report the preliminary explorations of engineering education exploiting Web 2.0 services, through iMechanica (http://imechananica.org). Hosted at Harvard University and powered by Drupal, an open-source content management system (CMS), iMechanica provides a platform for researchers, educators and students to experiment with innovative ideas on engineering education. For example, instructors can post syllabi, lecture notes, as well as slides and videos on iMechanica. Interested learners can view and study these posts, raise questions and make comments. Quite often an active discussion produces more useful information beyond an original post, and inspires new posts and further discussions. Furthermore, one can subscribe to these discussions through RSS feeds and is notified whenever a new entry is added to the thread of discussion. The instructing and learning through iMechanica are not limited within a specific institution or a specific curriculum. Anyone in the world can join such education processes, as either an instructor or a student, or both. These preliminary explorations of engineering education in the age of Web 2.0 hold the promise to build an online life-long learning environment without boundary.
Numerical Simulations of Dynamics and Heat Transfer Associated With a Single Bubble in the Presence of Noncondensables
Authors: Wu Jinfeng , Dhir Vijay K.
Published: May 2009

Under subcooled boiling conditions, the liquid may contain dissolved noncondensabe gases. During phase change at the bubble-liquid interface, noncondensable gases will be injected into the bubble along with vapor. Due to heat transfer into sub-cooled liquid, vapor will condense in the upper regions of the bubble and the bubble interface is impermeable to noncondensables. As a result, noncondensabe gases will accumulate at the top of bubbles. This existing gradient of noncondensable concentration inside bubble determines the saturation temperature gradient around the bubble surface. The nonuniform saturation temperature may cause a difference in surface tension which would give rise to thermocapillary convection in the vicinity of the interface. So far, this description is merely a hypothesis. It is felt that much inspection is in vital demand to clarify the uncertainty as to the role of noncondensables throughout this process. In this study, air is taken as noncondensable gas, and the aim is to investigate the effects of noncondensable air on heat transfer and bubble dynamics. The results from a numerical procedure coupling level set function with moving mesh method show the evidence of effects of noncondensable air imposed on heat transfer and the induced flow pattern is presented as well.
Dynamic Modeling and Simulation of an Optimized Proton Exchange Membrane Fuel Cell System
Authors: Outeiro M. T. , Chibante R. , Carvalho A. S. , de Almeida A. T.
Published: May 2009

Hydrogen and fuel cells are widely regarded as the key to energy solutions for the 21st century. These technologies will contribute significantly to a reduction in environmental impact, enhanced energy security and development of new energy industries. Fuel cells operating with hydrogen have the potential to contribute to the transition for a future sustainable energy system with low-CO2 emissions. In this paper a dynamic PEM fuel cell model, implemented in Matlab/Simulink, is presented. In order to estimate the PEM fuel cell model parameters, an optimization based approach is used. The optimization is carried out using the Simulated Annealing (SA) algorithm. This optimization process evolves converging to a minimum of the objective function. The flexibility and robustness of SA as a global search method are extremely important advantages of this method. A good agreement between experimental and simulated results is observed. This optimized PEM fuel cell model can significantly help designers of fuel cell systems by providing a tool to perform accurate design and consequently to improve system efficiency.
Compressive Residual Stresses Effect on Fatigue Life of Rolling Bearings
Authors: Cretu Spiridon S. , Benchea Marcelin I. , Cretu Ovidiu S.
Published: May 2009

The fatigue life tests carried out on two groups of ball bearings confirm the positive influence of the compressive residual stresses induced by a previous loading in the elastic-plastic domain. The values of residual stresses are numerically evaluated by employing a three-dimensional strain deformation analysis model. The model is developed in the frame of the incremental theory of plasticity by using the von Mises yield criterion and Prandtl-Reuss equations. To consider the material behaviour the Ramberg-Osgood stress-strain equation is involved and a nonlinear equation is considered to model the influence of the retained austenite. To attain the final load of each loading cycle the two bodies are brought into contact incrementally, so that for each new load increment the new pressure distribution is obtained as the solution of a constrained system of equation. Conjugate gradients method in conjunction with discrete convolution fast Fourier transform is used to solve the huge system of equations. Both the new contact geometry and residual stresses distributions, are further considered as initial values for the next loading cycle, the incremental technique being reiterated. The cyclic evaluation process of both plastic strains and residual stresses is performed until the material shakedowns. Comparisons of the computed residual stresses and deformed profiles with corresponding measured values reveal a good agreement and validate the analysis model. The von Mises equivalent stress, able to include both elastic and residual stresses, is considered in Ioannides-Harris rolling contact fatigue model to obtain theoretical lives of the ball bearings groups. The theoretical analysis reveals also greater fatigue lives for the ball bearings groups with induced residual stresses than the fatigue lives of the group without induced residual stresses.
A Smart Assembly Undergraduate Laboratory
Authors: Long James , Anderson John C. , Sun Wangping
Published: May 2009

Smart assembly is a term that is being used to describe the concept of integration of virtual and real time tools and methods to achieve gains in productivity, lead time, quality, and agility in the manufacturing arena. This paper describes efforts and successes in planning and implementing a laboratory to teach undergraduate engineering students these tools and allow for applied research. Between 1973 and 2004 the percentage of goods consumed in the US that are produced in the US has dropped from 83% to 24%. Much of this decrease has been driven by globalization. Goods can be manufactured for 30 to 50% less in China, for example, than in the US. This poses a very real threat to the manufacturing base of the US. An alternative business model that places the production closer to the customer is gaining favor as at least partial solution to this problem. This model is driven by automation and systems engineering to decrease cost and increase flexibility. The lab at Oregon Institute of Technology will use a collection of small robots and standard material handling devices to model physical systems. Discrete event simulation programs will be developed that allow engineers to quickly and easily model changes. This project is a collaboration of the Manufacturing and the Computer Software Engineering Technology programs. It is being driven by a series of faculty and student projects.
Finite Element Simulation of Piezoelectric Wafer Active Sensors Based Structural Health Monitoring
Authors: Liu Weiping , Giurgiutiu Victor
Published: May 2009

Crack detection with piezoelectric wafer active sensors (PWAS) is emerging as an effective and powerful technique in structural health monitoring (SHM). Modeling and simulation of PWAS and host structure play an important role in the SHM applications with PWAS. For decades finite element method has been extensively applied in the analysis of piezoelectric materials and structures. The advantage of finite element analysis over analytical solutions is that stress and electrical field measurements of complex geometries, and their variations throughout the device, are more readily calculated. FEM allows calculation of the stress and electric field distributions under static loads and under any applied electrical frequency, and so the effect of device geometry can be assessed and optimized without the need to manufacture and test numerous devices. Coupled field analysis taking both mechanical motions and electrical characteristics into account should all be employed to provide a systemic overview of the piezoelectric sensors/actuators (even arrays of them) and the host structures. This use of PWAS for SHM has followed two main paths: (a). Wave propagation (b). Electromechanical impedance; Previous research has shown that PWAS can detect damage using wave reflections, changes in wave signature, or changes in the electromechanical (E/M) impedance spectrum. The primary goal of this paper is to investigate the use of finite element method (FEM) to simulate various SHM methods with PWAS. For the simulation of Electro-mechanical (E/M) impedance technique, simple models, like free PWAS of different shapes and 1-dimmension beam with PWAS are investigated and the simulated structural E/M impedance was presented. For the wave propagation SHM technique, a long beam with several PWAS installed was studied. One PWAS is excited by tone burst signals and elastic wave will propagate along the beam. The existence of a crack will affect the structure integrity and the echo reflected by crack can be observed through the simulations. By using the coupled field elements, direct simulation of electro-mechanical interaction of the PWAS and the host structure was made possible. The electrical potential generated on the PWAS surface by the stimulation of elastic wave can be examined in our FEM analysis. The simulation results are then compared to analytical calculation and experimental data.
Optimization of MEMS Design for a Synchronous Magnetic Sensor
Authors: Chandrasekaran S. , Berkcan E.
Published: May 2009

Microelectromechanical systems offer variety of advantages such as small size, higher sensitivity, low cost because of mass fabrication capabilities and ease of implementation. Thin film cantilever based devices have been successfully used for variety of applications not limited to chemical vapors for chemical agents, biological warfare agents, contaminants in water, explosives, acoustics, vibration monitoring, flow sensing, viscosity and density measurements, antibody, pathogen detection, acceleration, shock sensing and magnetic field sensing. Thin film cantilevers can easily realized on silicon and other surfaces. Microcantilevers supported on one edge of the substrate can be designed to demonstrate very high sensitivity to very less force of the order of piconewtons. These structures could be extended for application in gas sensing if chemically sensitive layer is added on to the cantilever. The dimensions of the cantilever determine the sensitivity. Cantilevers as thin as few tenths of nanometer in thickness has been successfully demonstrated. Challenge associated with these devices when used as a sensor is their response to shock and acceleration.
3-D Simulation of Sedimentation in Turbidity Currents
Authors: Hormozi S. , Firoozabadi B. , Ghasvari Jahromi H.
Published: May 2009

The gravity currents on the inclined boundaries are formed when the inflow fluid has a density difference with the ambient fluid and a tangential component of gravity becomes the driving force. If the density difference arises from the suspended particles, the currents are known as particle-laden density currents, or turbidity currents in which the local density depends on the concentration of particles. A low Reynolds k-ε turbulent model is used to simulate three dimensional turbidity currents. Also some laboratory tests were conducted to study the 3D flow resulting from the release of particle laden density currents on a sloping surface in a channel of freshwater via a sluice gate. Kaolin was used as the suspended material. The height, width, velocity and concentration profiles of turbidity currents were calculated and compared with the experimental data and showed good agreement. Different settling velocity formulas based on, first, solitary particle and, second, considering the effect of dispersed particles thorough the fluid are exerted in the concentration equation and the results compare with each other. Also the sedimentation heights of the turbidity current are simulated which are compatible with the experimental data.
Opto Mechanical Package Development
Authors: Kryger Graham , McCarter Anika
Published: May 2009

The focus of this student project was to design and develop a laser diode opto-mechanical package for nLight Photonics Company. This design process involved examining the existing models of the package design and assessing the manufacturing process. Limitations regarding tooling, alignment, and package materials were also taken into account. The package was modeled in SolidWorks, considering these limiting parameters and changing the size and shape of the package from previous models in order to increase spatial efficiency. Analysis of the package was performed to ensure heat would dissipate properly from the diode, and that the diode would operate within the specified temperature range. The thermal analysis was performed using various methods, including a simple spreadsheet analysis and specialized software. This paper will examine each of these design processes in more detail.
Sensor Test Platform for Rapid Pressure Indicating Sensors
Authors: Goblish Adam , Hahn Lincoln , Larson Justin , Monk Ray , Hu Zhong , Delfanian Fereidoon
Published: May 2009

Maximum life cycles for rapidly pressurized cylinders can be obtained by knowing precisely the number and severity of pressurizations of the cylinder through sensor measurement. The development of sensors that are capable of quickly registering pressurizations and stresses in a pressurized cylinder requires a test platform that can rapidly pressurize a cylinder while being able to control speed of pressurization, pressure in cylinder, cyclical timing of pressurization, and the number of pressurizations. In this paper, the test platform is being developed using an impact load to rapidly pressurize the hydraulic fluid in the hydraulic cylinder. The impact pressure is created by a falling mass which strikes the piston of a hydraulic cylinder, which creates an impact pressure from the impact load. Due to the nature of the cylinder, a small amount of air remains in the cylinder; by varying the amount of air in the cylinder the pressurization rate can be controlled. The platform will allow for the gathering of vital information regarding the applications of varying pressurization time and magnitude and the ability of various sensors to register and properly determine the magnitude of the pressurization. Information gathered through the usage of this test platform will be vital to several departmental projects; including the stress assessment and fatigue prediction of thick pressurized cylinders.
Magnetic Heating Analysis for Nanoparticle Systems With Low Tc Suitable for Magnetic Hyperthermia
Authors: Hayek Saleh S. , Chen Ching-Jen
Published: May 2009

Quality magnetic heating nanoparticle systems made of ferromagnetic and superparamagnetic materials were developed for hyperthermia treatment of cancer. Magnetic nanoparticles were prepared from a mixture of magnetic and non magnetic elements using, mainly, co-precipitation process (chemical methods). The nanoparticles were developed in ternary systems, with zinc gadolinium iron (ZnxGdyFe) and manganese zinc iron (MnxZnyFe) alloys with different concentrations. The nanoparticle systems developed generate sufficient heat at room temperature and stops heating at the measured Curie temperature Tc. The power dissipated from nanoparticle systems was calculated from the area enclosed by the hysteresis loop. A mathematical formula for the calculation of heating power was derived and showed to be in good agreement with those calculated from hysteresis loop and calorimetric methods.
Repair of Stiction Failed MEMS Using Structural Vibrations
Authors: Goettler Drew , Savkar Amit , Murphy Kevin , Leseman Zayd Chad
Published: May 2009

It has been shown in recent times that the use of structural vibrations is a viable approach in repairing stiction failed MEMS cantilever beams. It has also been observed that such a technique is sensitive to various parametric values associated with the de-sticking of these beams. In the current paper we present experimental results which characterize the ideal cantilever beam. An analytical model of stiction failed MEMS cantilever beams under electrostatic actuation is presented. Physical parameters such as stiffness, bending rigidity, damping, excitation voltage, etc. are incorporated in terms of Mathieu parameters to study the stability of the system. An experimental characterization of natural frequency, Young’s Modulus, and damping ratio, which form important components of the analysis, is presented. Accompanying these results is a description of the experimental set up used for finding these parameters. Experiments were performed at both atmospheric and vacuum pressures. An interferometric microscope mounted above the glass window of the vacuum chamber was used to determine the crack length of each beam and observe the profiles of the arrays of microcantilevers in-situ. A Laser Doppler Vibrometer was used for determination of characterization parameters. The microcantilevers were fabricated using the SUMMiT IV process of Sandia National Laboratories. Structural vibrations were induced by placing an alternating voltage on a cofabricated actuation pad located under the microcantilevers near their anchor point. Theoretical modeling shows the dependence of physical parameters that lead to stiction repair.
A Model for Prediction of Temperature in Disk Pair in Dry Friction Contact
Authors: Homani A. , Farhang K.
Published: May 2009

In applications involving substantial friction, surface failure is an inevitable phenomenon. Friction induced failure typically involves the generation of considerable heat. Existence of significant frictional force leads to relatively high interface temperature as a result of dynamic nature of flash temperatures at the contact areas. A first step in predicting friction induced failure is to develop an accurate thermo-mechanical model of the friction system. A thermo-mechanical model is developed in this paper based on a lumped parameter representation of a two-disk brake. A disk is viewed as consisting of three main regions, (1) the surface contact, (2) the friction interface, and (3) the bulk. The lumped parameter model is obtained by dividing a disk into a number of concentric rings and stacked layers. The friction layer contains both the interface and contact elements, each include the equivalent thermal capacitance and conductive resistance. The contact capacitance and resistance are described in terms of the elastic contact interaction between the surfaces of the two disks. Therefore they are obtained using the Greenwood and Williamson model for contact of rough surfaces. Each is described as a statistical summation of the micron-scale interaction of the surfaces. The model is shown to provide accurate prediction of bulk temperature using a dynamometer test on a carbon composite disk pair.
Small-Sized Wind Power Generator Using Nd-Fe-B Permanent Magnets
Authors: Sakamoto Haruo
Published: May 2009

Today, clean or renewable energy is highly demanded for realization of the sustainable earth. The most promising methods among renewable energies are wind power, solar, water power, and biomass energies. They need to apply generators except for a solar energy case. The first study for development of generators was product dissection of eight different generators, which resulted that there seem no rule for the most suitable design approach. They include 4 wind power, two water, and 2 vehicle generators. In such dissected 8 generators there are all different coil number, magnet number, way of coil winding, phase for coil connection, and etc. Starting the study of disk-shape rotor with magnets in the outer periphery, the capability of power generator was studied, and it resulted that it is not sufficient. As a second step, an axial gap type generator was investigated using rare-earth permanent magnets and core-less coils for both face sides for coil assembly. The first objective of this research is to establish an effective wind power generator, which should be useful even under a weak wind condition like at a ground level. The idea of core-less coil (without pulling against each other between coils and magnets) is to obtain easy rotation in the area where is not so strong wind blow condition. The second objective of this research is to establish a hybrid wind and solar power energy system. The system is considered to be used in the case of disaster event such as an earthquake occurrence. Because big earthquakes are expected in the coming 30–40 years with the probability of 40–50% in the south part of Japan, the self-powered lights need in such a disaster occurrence case. Although wind power generators are effective at mountainous areas, we think we need to consider to apply a wind power generator in populated areas. Combining a wind power generator with a solar cell, a self-powered street light can be utilized. In the following, the design and development of generator and a possibility of the hybrid system by wind power and solar cell are reported.
A Freshman Engineering Education Experience
Authors: Karimi Amir
Published: May 2009

This paper describes a freshman engineering educational experience at The University of Texas at San Antonio (UTSA). It highlights the first year engineering curriculum and an academic support system that is designed for student success during the freshman year. Traditional course work in calculus, chemistry, calculus based physics, introductions to engineering, engineering graphics, and writing courses are a part of the freshman engineering curriculum. The university offers a number of academic support programs to help freshman students a smooth transition from high school to college life. A Freshmen Seminar course, which is designed to enhance students’ educational experiences during the freshman year, is an important element of the university’s academic support system. This paper briefly describes the content of an introductory course in engineering and the Freshman Seminar. It also describes some of the programs within the university that are implemented to improve student success during the freshman year.
Carbon Neutral Production of Syngas via High Temperature Electrolytic Reduction of Steam and CO2
Authors: Stoots C. , O’Brien J. , Hartvigsen J.
Published: May 2009

This paper presents the most recent results of experiments conducted at the Idaho National Laboratory (INL) studying coelectrolysis of steam and carbon dioxide in solid-oxide electrolysis stacks. Two 10-cell planar stacks were tested under various gas compositions, operating voltages, and operating temperatures. The tests were heavily instrumented, and outlet gas compositions were monitored with a gas chromatograph. Measured outlet compositions, open cell potentials, and coelectrolysis thermal neutral voltages compared reasonably well with a coelectrolysis computer model developed at the INL. Stack ASRs did not change significantly when switching from electrolysis to coelectrolysis operation.
Experimental and Numerical Study of Dense Layered Nano-Energetic Materials
Authors: Amini Manesh Navid , Coffey Kevin R. , Kumar Ranganathan
Published: May 2009

This paper deals with the reaction of dense Metastable Intermolecular Composite (MIC) materials. The energy density of MIC nanocomposite materials is much higher than that of conventional energetic materials. The reaction of a multilayer thin film of aluminum and copper oxide has been studied by varying the substrate material and thicknesses, to vary the heat loss during the reaction of the MIC material. The in-plane speed of propagation of the reaction was experimentally determined using a time of-flight technique. The experiment shows that the reaction is completely quenched for a silicon substrate having an intervening silica layer of less than 200 nm. The speed of reaction seems to be constant at 40 m/s for silica layers with thickness greater than 1 μm. Different substrate material such as glass was also used. A numerical analysis of the thermal transport from the reacting film shows that the temperature profiles become self similar for substrate thicknesses larger than 1 μm., the maximum temperature stays constant for both silica and composite silica/silicon substrates, showing the effectiveness of the composite substrates to control the heat lost from the reaction, both experimentally and numerically.
Numerical Simulation of Thermal Stress Fields in Thermoplastics in a Pulsed Laser Welding Process
Authors: Kowalski Gregory J. , Whalen Richard A.
Published: May 2009

A numerical simulation code is developed and used to derive relationships between the incident laser radiation, the thermal stress field, and the size and shape of the heat affected (HAZ) and melt zones for a pulsed laser transmission welding process. The material used in the investigation is a high density polyethylene thermal plastic. The numerical model uses the Fourier heat conduction thermal model and the welding process involves the lap welding of two thin layers of thermoplastic films with the welding conditions of a transparent material over a semi-transparent or opaque material. The Fourier model is valid due to the high thermal pulse velocity through the material. The results are compared to the published data on thermoplastic welding criteria and the legitimacy of these criteria are discussed.
Renewable Energy and Hybrid Turbine-Fuel Cell Cogeneration System’s Predicted Performance
Authors: Kowalski Gregory J. , Zenouzi Mansour
Published: May 2009

A normalized, general approach for determining the combined performance of a hybrid turbine-fuel cell cogeneration system with a renewable energy source, such as a solar thermal system is presented. The hybrid-cogeneration system provides required electric power as well as satisfying simultaneous heating loads. In this paper a system level analysis that includes practical values of heat exchangers, pumps, and storage equipment is presented. The use of the ratio of the thermal load to required power parameter (HLRP), which has been previously used by the authors to scale energy systems, allows the performance to be quickly determined and preliminary carbon dioxide production rates and cost effects to be estimated. The present paper will focus on a solar thermal system as renewable energy to illustrate the development of this technique and its integration with the hybrid fuel cell cogeneration system. Practical values of solar collector efficiency and storage tank efficiency are included. The analysis will focus on matching the transient characteristics of the power and thermal loads with those of the renewable energy system. Performance measures used to evaluate the investigated designs include the energy utilization factor and the carbon dioxide produced per unit power output. The information provided by the performance graphs can be used to estimate costs for each system and to easily determine which system is the most efficient for satisfying energy requirements and reducing green house gas emissions. The results provide site planners and physical plant operators with initial information that can be used to design new facilities or effectively integrate large plant expansion that include renewable energy systems in a manner that will minimize energy requirements and reduce pollution effects.
Development of a Robust Observer for Constrained Nonlinear Systems
Authors: Kfoury G. A. , Chalhoub N. G.
Published: May 2009

The equations of motion for a constrained multi-body system are usually governed by a set of highly nonlinear differential-algebraic (D-A) equations. For nonlinear complex systems, the substitution method cannot be implemented to eliminate the superfluous coordinates. Thus, the differential-algebraic form of the equations of motion has to be retained. For control purposes, the state variables of the system should be available for the computation of the control signals. The current study presents a general procedure for developing a robust nonlinear observer capable of yielding accurate estimates of the state variables for a complex system whose dynamics are governed by a set of D-A equations. To assess the viability of the proposed approach, the multi-body dynamics of a piston/connecting-rod/crankshaft mechanism for a single cylinder internal combustion engine is considered in this study. The equations of motion account for both the rigid and flexible motions of the crank-slider mechanism. The simulation results demonstrate the capability of the proposed observer in accurately estimating all the state variables of the system including the superfluous ones. They illustrate the robustness of the observer to both structured and unstructured uncertainties. Moreover, they demonstrate that the nominal constraint equations are satisfied by the estimated state variables.