bluuebunny/crossref_metadata_2025 huggingface dataset:
Micro-Macro Characterization of Effective Properties for Fibrous Composites With Parallelogram Cells and Imperfect Contact Condition
Authors: Rodriguez-Ramos Reinaldo , Lo´pez-Realpozo Juan Carlos , Guinovart-Di´az Rau´l , Bravo-Castillero Julia´n , Otero J. A. , Sabina F. J.
Published: August 2012

In this work, two-phase parallel fiber-reinforced periodic piezoelectric composites are considered wherein the constituents exhibit transverse isotropy and the cells have different configurations. Two types of imperfect contact at the interface of the composites are studied: a) imperfect contact via spring model, b) three phase model. Simple closed-form formulae are obtained for the effective properties of the composites with both types of contact and different parallelogram cells by means of the asymptotic homogenization method (AHM). Some numerical examples and comparisons with other theoretical results illustrate that the model is efficient for the analysis of composites with presence of parallelogram cells and imperfect contacts.
Improving Vibration Based Damage Detection With Optical Measurements
Authors: Ward Andrew S. , Sarigul-Klijn Nesrin
Published: August 2012

Damage detection and localization allow for automated real-time monitoring of engineered systems. The benefits of such a system include improved safety, lower maintenance costs, and higher reliability. Many of the early works focus almost exclusively on numerical simulations of real systems, with very little experimentally acquired data used in detection. Introducing real world data complicates the analysis significantly by requiring noise reducing techniques to acquire legitimate results. Further, the cost of obtaining enough data to fully define a damaged system can quickly become prohibitive. This paper focuses on damage detection schemes carried out through empirical means. First a concept proving scheme is used by which data about the system is collected through accelerometer data. The damage detection scheme requires the reduction of a large set of data to one or two descriptive eigen parameters. Second, the scheme is repeated using optically gathered data through use of a high speed camera and software image manipulation tools. Damage detection is shown to be possible under the same conditions and initial parameters. Localization of the damage, however, is shown to require sensor information from multiple locations. Further still the optically based method is shown to supplement a failed detection by other means.
Comparison of Experimental Results to CFD Models for Blending in a Tank Using Dual Opposing Jets
Authors: Leishear Robert A. , Lee Si Y. , Fowley Mark D. , Poirier Michael R. , Steeper Timothy J.
Published: August 2012

Research has been completed in a pilot scale, eight foot diameter tank to investigate blending, using a pump with dual opposing jets. The jets re-circulate fluids in the tank to promote blending when fluids are added to the tank. Different jet diameters and different horizontal and vertical orientations of the jets were investigated. In all, eighty five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of several miles of two inch diameter, serpentine, vertical cooling coils below the liquid surface for a full scale, 1.3 million gallon, liquid radioactive waste storage tank. Two types of tests were performed. One type of test used a tracer fluid, which was homogeneously blended into solution. Data were statistically evaluated to determine blending times for solutions of different density and viscosity, and the blending times were successfully compared to computational fluid dynamics (CFD) models. The other type of test blended solutions of different viscosity. For example, in one test a half tank of water was added to a half tank of a more viscous, concentrated salt solution. In this case, the fluid mechanics of the blending process was noted to significantly change due to stratification of fluids. CFD models for stratification were not investigated. This paper is the fourth in a series of papers resulting from this research (Leishear, et.al. [1–4]), and this paper documents final test results, statistical analysis of the data, a comparison of experimental results to CFD models, and scale-up of the results to a full scale tank.
Self-Sustained Partial Oxidation of N-Butane Triggered by a Hybrid Start-Up Process for Micro-SOFC Devices
Authors: Santis-Alvarez Alejandro J. , Nabavi Majid , Poulikakos Dimos
Published: August 2012

Micro-solid oxide fuel cell (SOFC) power plants are emerging as a promising alternative for power generation for portable applications due to their low emission of pollutants, high power density and fuel flexibility. Some of the challenges for developing such micro-SOFC power plants are geometrical compactness, fast start-up and self-sustainability at operating conditions. In this work, we present a hybrid start-up process for a micro-SOFC power plant using catalytic oxidation of n-butane over Rh-doped Ce0.5Zr0.5O2 nanoparticles in a small-scale reactor to provide the necessary intermediate operating temperature (500–550 °C) and syngas (CO + H2) as fuel for a micro-SOFC membrane. A short heating wire is used to generate the heat required to trigger the oxidative reaction. The hybrid start-up is investigated for partial oxidation (POX) and total oxidation (TOX) ratios at one specified flow rate. Additionally, the variation of electrical heating time and its influence on the hybrid start-up is evaluated.
Dynamic Measurements of an Industrial Electric Motor Stator Core
Authors: Hambric Stephen A. , Fahnline John B. , Campbell Robert L.
Published: August 2012

Measurements of the dynamic and acoustic behavior of a commercial electric motor stator are presented. An Allis-Chalmers motor stator core, before and after winding and potting, was excited with drives on the teeth in tangential (circumferential and axial) and radial directions. The vibration response was decomposed into its circumferential harmonics and modes of vibration. The core was mounted in a sturdy, asymmetric housing, and showed significant harmonic character. The high circumferential order ring modes of the bare stator are limited to frequencies below those of the fundamental modes of the stator teeth. When the teeth are wound and potted, however, the ring modes resemble those of contiguous cylindrical shells, increasing in frequency with mode order. Also, the vibration response of the stator decreases significantly when it is wound and potted, particularly for drives tangential to the teeth. In spite of the reductions, drives tangential to the teeth still cause vibration comparable to, and sometimes higher than, that induced by radial tooth drives.
Measurement and Model Correlation of Specific Heat Capacity of Water-Based Nanofluids With Silica, Alumina and Copper Oxide Nanoparticles
Authors: O’Hanley Harry , Buongiorno Jacopo , McKrell Thomas , Hu Lin-wen
Published: August 2012

Nanofluids are being considered for heat transfer applications. However, their thermo-physical properties are poorly known. Here we focus on nanofluid specific heat capacity. Currently, there exist two models to predict a nanofluid’s specific heat capacity as a function of nanoparticle concentration and material. Model I is a straight volume-weighted average; Model II is based on the assumption of thermal equilibrium between the particles and the surrounding fluid. These two models give significantly different predictions for a given system. Using differential scanning calorimetry, the specific heat capacities of water based silica, alumina, and copper oxide nanofluids were measured. Nanoparticle concentrations were varied between 5wt% and 50wt%. Test results were found to be in excellent agreement with Model II, while the predictions of Model I deviate very significantly from the data.
Vehicle Risk Level Estimation by Using Experimental Trajectories in Bend
Authors: Koita Abdourahmane , Daucher Dimitri , Fogli Michel
Published: August 2012

This paper tackles the general context of road safety, focussing on the light vehicles safety in bends. It consists to use a reliability analysis in order to estimate the failure probability of vehicle trajectories. Firstly, we build probabilistic models able to describe measured trajectories in a given bend. The models are transforms of scalar normalized second order stochastic processes which are stationary, ergodic and non-Gaussian. The process is characterized by its probability density function and its power spectral density estimated starting from the experimental trajectories. The probability density is approximated by a development on the Hermite polynomials basis. The second part is devoted to apply a reliability strategy intended to associate a risk level to each class of trajectories. Based on the joint use of probabilistic methods for modelling uncertainties, reliability analysis for assessing risk levels and statistics for classifying the trajectories, this approach provides a realistic answer to the tackled problem.
Challenges and Methods in Better Teaching of Engineering
Authors: Mekid Samir
Published: August 2012

New advanced technologies and subjects related to high level research in engineering are expected to be bridged to undergraduate teaching at various levels. Hence, innovative teaching is required to address new challenges. A rapid overview of current teaching methods is presented in this paper highlighting related issues. Problem based learning and enquiry based learning are still under investigations to be adapted to most engineering courses. It is expected that students would be able to take control of their own learning with a certain freedom, or, given the opportunity to solve engineering problems without prior knowledge of the subject. Innovative teaching methods have to be designed and established to enable clear knowledge transfer to students with continuous assessment of the learning outcomes over regular periods of teaching (e.g. every semester). This paper discusses, also, a number of challenges encountered in teaching engineering with an example.
Influence of Vegetation Moisture on Combustion of Pyrolysis Gases in Wildland Fires
Authors: Dover Selina C. , Dahale Ambarish R. , Shotorban Babak , Mahalingam Shankar , Weise David R.
Published: August 2012

Since wildland fires occur in living vegetation, the fuel moisture content must be considered in order to correctly predict the behavior of the fire. One facet of combustion of pyrolysis gases that has not been considered in previous research is the effect of moisture on the combustion process. This effect is investigated by using CHEMKIN software to study an opposed diffusion flame model for three pyrolysis fuels relevant to wildfires. The effect of moisture on flame structure is investigated by varying the mole fraction of water vapor in the fuels, with air as oxidizer. In all cases, the flame extinguishes when the water mole fraction is between 0.55 and 0.65. O2 and H are the only components that exhibit a significant change in concentration under these conditions.
The Edge Effects on the Lattice Thermal Conductivity of Graphene Nanoribbons
Authors: Wei Z. , Ni Z. , Bi K. , Wang J. , Chen Y.
Published: August 2012

The thermal conductivity of graphene nanoribbons was investigated with nonequilibrium molecular dynamics simulation methods. The results show that the thermal conductivity of nanoribbons lined with zig-zag edges is higher than that with arm-chair edges for the samples with the same width. The phonon density of states is extracted from the molecular dynamics simulation to quantitatively explain the difference between the thermal conductivities of the two kind nanoribbons. The effects of vacancy on the thermal conductivity of nanoribbons are also investigated and it is found the defects on the edge zone play little role than that located in the interior zone of nanoribbons in reducing thermal conductivities.
Prediction Capabilities of Damped Updated Finite Element Models
Authors: Arora Vikas
Published: August 2012

Model updating techniques are used to correct the finite element model of a structure using experimental data such that the updated model more correctly describes the dynamic properties of the structure. One of the applications of such an updated model is to predict the effects of making modifications to the structure. These modifications may be imposed by design alterations for operating reasons. Most of the model updating techniques neglect damping and so these updated models can’t be used for accurate prediction of complex frequency response functions (FRFs) and complex mode shapes. In this paper, a detailed comparison of prediction capabilities of parameter-based and non parameter-based damped updated methods for structural modifications is done. The suitability of paramter-based and non parameter-based damped updated models for predicting the effects of structural modifications is evaluated by laboratory experiment for the case of an F-shape test structure. It is concluded that parameter-based damped updated models are likely to perform better in predicting the effects of structural modifications.
A Leader-Following Formation Control of a Group of Mobile Robots
Authors: Lee Ho-Hoon
Published: August 2012

This paper proposes a leader-following formation control strategy for a group of mobile robots. The nonholonomic constraints of the mobile robots, instead of the usual point-mass assumption, are taken into account in the design of the formation control. The proposed formation control computes desired driving force and steering torque, instead of desired translational and angular velocities, for each robot. The proposed control consists of a formation control scheme and a kinematic trajectory generation scheme for the leader of a group. In the design of the proposed control schemes, the Lyapunov stability theorem is used as a mathematical tool. The leader follows its desired trajectory while the rest of robots are following the leader in a specified formation. Under certain conditions, the proposed formation control guarantees asymptotic stability while keeping all internal signals bounded. The effectiveness of the proposed control has been shown with realistic computer simulations.
Characterizing Nonlinear Dynamic Systems With Periodicity Ratio and Statistic Hypothesis
Authors: Han Lu , Dai Liming
Published: August 2012

By introducing a statistical hypothesis to Periodicity Ratio, the efficiency and accuracy of diagnosing the nonlinear characteristics of dynamic systems are improved. Overlapping points in a Poincare map are verified on a statistically sound basis. The characteristics of nonlinear systems are investigated by using the present approach. The numerical results generated by the approach are compared with that of the conventional approaches.
Design of a Blended Wing Body UAS With Hybrid Propulsion
Authors: Koster Jean , Balaban Scott , Hillery Derek , Humbargar Cody , Nasso Derek , Serani Eric , Velazco Alec
Published: August 2012

Student engineering teams developed a 3 m scale model aircraft, named Hyperion, inspired after the NASA-Boeing X48-B blended wing body to use as a test bed for advanced technical studies. The design concept includes a novel hybrid gas/biodiesel-electric power train as a green aircraft technology. The hybrid propulsion system allows for new concepts of operation in unmanned vehicles as it can operate in an internal combustion-only, electric-only, or hybrid mode. The aircraft is designed through a collaboration of 3 international universities: the University of Colorado Boulder, the University of Sydney, AUS, and the University of Stuttgart, GER. The Hyperion aircraft has a blended fuselage and wing to utilize advanced aircraft design and aerodynamic efficiency. The flying wing architecture is a fuel efficient platform to demonstrate the latest developments in ‘green’ aircraft technology. The optimal design requires a full systems engineering analysis, including aerodynamic and structural analysis of the vehicle; design of the flight mechanics, navigation, and control systems. The vehicle is fabricated primarily from composite materials. Hyperion’s unique architecture and advanced subsystems establish novel technologies that can be incorporated into UAV, General Aviation, and larger aircraft.
Gage Repeatability and Reproducibility Investigations of a Test Rig Using ANOVA/Xbar-R Method
Authors: Balta Berna , So¨nmez Fazıl O¨nder , Cengiz Abdu¨lkadir
Published: August 2012

In an experimental study, good measurement systems are important for approaching successful decisions. The assessment of a measurement system is known as “Gage Repeatability and Reproducibility” (GR&R). “Measurement System Analysis” (MSA) should be performed at the beginning of an experimental study to ensure that the information to be collected are true representation of what is occurring in the experiment. Experimental data collected under the same condition usually show variation, which arises partly from the experimental system, partly from the measurement devices and partly from the operator who makes the measurements. MSA helps to differentiate the contribution of each source to the randomness of the data. In this way, one may see whether there is a need to reduce the measurement variation so that the data reflects basically the experimental variation. Besides, MSA gives quantitative measures for repeatability and reproducibility. Repeatability is the variation in repeated measurements taken by the same operator under the same experimental conditions. Reproducibility is the variation in data obtained by different operators taking the measurement with the same setup under the same conditions. These are measures of the consistency and precision of the data. GR&R is the most common MSA tool that analyzes the viability of an experimental set-up. Resultant GR&R will indicate overall measurement system variation as the sum of repeatability variation and reproducibility variation. Generally, GR&R % gives a measure of the suitability of the measurement system to yield acceptable data for statistical studies such as “Design Of Experiments” (DOE), “One Factor At a Time” (OFAT), “Response Surface Methodology”, etc. [1, 2]. In this paper, “Analysis of Variance” (ANOVA) and the “Average and Range” (Xbar & R) methods are used to assess the capability of a laboratory made measurement device, which is used for the investigations of a belt drive system efficiency. GR&R is applied at the design stages of the construction of the test rig and final application is presented in this study. The results prove that the test rig is capable of making experimental studies using statistical methods such as DOE and Response Surface Methodology.
Development of a Detailed Multi-Body Computational Model of an ATV to Address and Prevent Child Injuries
Authors: Thorbole Chandrashekhar K. , Aitken Mary , Graham James , Miller Beverly , Mullins Samantha Hope , Eoff Shane
Published: August 2012

Better insights into ATV crash mechanisms are needed to facilitate effective prevention strategies. Rollover crashes and resulting injuries represent major problems associated with ATVs. These problems are aggravated with the rider is a young child, since all ATVs are rider active machines. Serious injuries associated with child use of adult ATVs are an increasing problem in the United States and other countries. The computational technique is used to develop a detailed adult size ATV. The computational model is developed using the biodynamic code MADYMO. Laboratory tests are conducted on the ATV to extract the dynamic characteristics of the ATV. The ATV model developed features a detailed suspension system. The computational model confidence is increased using a digitized surface to create the rigid body model. The computational ATV model is validated for its lateral stability using a laboratory tilt table test. The suspension system is validated using a drop test on a rigid floor. This validated model is used to simulate and understand crashes and parameters affecting the injury outcome. A Hybrid III six year old dummy is used during the laboratory tilt table test and for initial crash simulations. This paper demonstrates the methodology used to develop a crash analysis for an ATV driven by a six year old child. The computation model is used to recreate a forward flip rollover crash scenario.
Combustion-Driven Thermal Transpiration Based Minature SOFC Power Generation Device
Authors: Zeng Pingying , Wang Kang , Menapace Nancy , Ahn Jeongmin
Published: August 2012

A miniature pump was designed in this study, based on a catalytic combustion-driven thermal transpiration. The designed pump was further used to build a miniature power generator that has self-pumping and power generation integrated into one device, has no moving parts and operates only on thermal and electrochemical energy supplied by hydrocarbon fuels. A solid oxide fuel cell tested with this power generator obtained a power density of 40 mW.cm−2.
Design and Construction of a Solar-Powered Fluidyne Test Bed
Authors: Mason Jackson W. , Stevens James W.
Published: August 2012

Liquid piston Stirling engines (sometimes termed “fluidynes”) have been studied extensively and applied in a variety of energy conversion applications. They are attractive for low capital costs and simplicity of construction. In addition, their operation as external combustion engines allows for flexibility in primary energy sources which is a distinct advantage when a low-cost or free source of heat can be paired with their minimal construction costs. Disadvantages of these devices include relatively low efficiency and low power density. A solar-powered fluidyne test bed was constructed and operated at the University of Colorado at Colorado Springs. This test bed was composed of a fluidyne engine which was constructed from copper pipe and plastic tubing along with temperature and pressure instrumentation. The system was designed to be powered by a Fresnel lens concentrating solar energy. The concentrated solar energy from the Fresnel lens provided ample power to operate the test bed, and tests were run in a wide variety of conditions. Indicated work of this unloaded engine was shown to agree well with a simple theoretical model of a Stirling cycle.
Buckling Behavior of Glass-Fiber Reinforced Polyester Pultruded Columns
Authors: Srinivasan Malur N. , Chayakul Vanchak
Published: August 2012

Fiber-reinforced plastic materials are used for lightweight structural applications in engineering. This paper is intended to contribute to knowledge of the buckling behavior of glass-fiber reinforced polyester (GFRP) composite I-section pultruded columns. Columns of two different lengths: 5.5 ft and 8.33 ft were axisymmetrically or eccentrically loaded in compression, until failure and the mid-point lateral deflections were measured during loading. Euler’s theory was used to determine theoretical deflection for comparison with the experimentally determined ultimate loads in the axisymmetrically loaded columns. An equation derived from the differential equation of the deflection curve was used for comparison with the experimental load-deflection curves for the eccentrically loaded columns. Limited scanning electron microscopy was done to differentiate between the microscopic failures in I-section columns.
Oil Spill Clean Up Project
Authors: Post Scott
Published: August 2012

On April 20, 2010, the Deepwater Horizon oilrig sank in the Gulf of Mexico, resulting in an oil spill of 4.9 million barrels, one of the largest environmental disasters in United States history. In response to this disaster, the X Prize Foundation sponsored the Wendy Schmidt Oil Cleanup X Challenge, with a one million dollar top prize for engineers to develop better ways to clean up oil after an offshore oil spill. Inspired by the oil spill cleanup challenge, a class project was developed for students in a junior-level fluid mechanics course to develop and implement an oil-spill cleanup solution. Students had one semester to design and build an oil spill cleanup device. At the end of the semester final testing took place in a 20-foot long water table, which was filled with water 6 inches deep. Then for each team of 3–4 students 100 mL of cooking oil was dispersed into the water table, and they had 20 minutes to recover as much of the oil as they could. The grading for the project was based in part on the percentage of the oil the students could recover in the allotted time. The students employed a wide range of techniques, including skimmers, scoopers, and absorbers. The students also had to write a report explaining how their model solution in the water table could be scaled up to full-scale use in an actual offshore oil spill.
A Novel Multi-Layer Poro-Elastic Model of Lung Deformation
Authors: Li Zhiliang , Long Xiang , Ilegbusi Olusegun J.
Published: August 2012

This paper presents a novel method to simulate flow and deformation of the lung. The lung is assumed to behave as a poro-elastic medium with heterogeneous elastic property. The method uses a flow-structure interaction technique to simultaneously model flow within the airway and deformation of the lung lobes. The 3D lung geometry is reproduced from 4D CT scan dataset obtained on real human subjects at a Cancer Center. The non-linear Young’s modulus is estimated in a parallel study based on similar CT scan dataset. The novelty of the present technique lies in the use of onion-layer grid with distributed spatial permeability. It allows prediction of the spatial lung displacement that could be used for tracking lung tumor during radiotherapy.
Effects of Inlet Flow Boundary Conditions on the Thermal Performance of a Plate-Fin Heat Sink With an Impinging Flow
Authors: Do Kyu Hyung , Kim Tae Hoon , Kim Sung Jin , Kim Myung Bae , Choi Byung-il , Han Yong Shik
Published: August 2012

This paper discusses the effect of inlet flow boundary conditions on the performance of a plate-fin heat sink with an impinging flow. The inlet flow boundary conditions of the plate-fin heat sink are decided by duct configurations and heat sink geometries. First, velocity distributions according to the inlet flow boundary conditions of the plate-fin heat sink are obtained using numerical simulations. These results clearly show that the inlet flow boundary condition is divided into two branches: one is uniformly impinging flow and the other is non-uniformly impinging flow. Also, the fluid characteristics of the plate-fin heat sink with an impinging flow according to the inlet flow boundary conditions are experimentally examined by measuring the stagnation pressure distributions on the bottom of the plate-fin heat sink. Based on Do et al., correlations for pressure drop and thermal resistance of the plate-fin heat sink with uniformly impinging flow are proposed. Also, pressure drop and thermal resistance correlations of the plate-fin heat sink with uniformly impinging flow are compared with those of the plate-fin heat sink with non-uniformly impinging flow using correlations suggested by Kim et al. Finally, it is shown that the plate-fin heat sink with uniformly impinging flow has a lower thermal resistance than the plate-fin heat sink the non-uniformly impinging flow when the dimensionless length of the plate-fin heat sink is small and the dimensionless pumping power is large.
Test of a Sliding Mode Controller for Trajectory Tracking of an Underactuated Surface Vessel
Authors: Siramdasu Yaswanth , Fahimi Farbod
Published: August 2012

Sliding mode controller for trajectory tracking of a surface vessel is designed based on a 3DOF dynamic model. The model has six unknown parameters. For parameter identification, four special test scenarios are defined to isolate and identify one of the six parameters at a time. The identification tests are performed on a robotic boat which has an onboard PC104 computer and a navigation sensor providing vessel’s dynamic states in real-time. The data from experiments are used to determine the model parameters. A sliding mode controller is designed based on the identified model, and is implemented and tested on a real robotic boat. The experiments show the excellent performance of the controller.
Solving Problems With Contradictions: The Challenge of 21st Century Engineering Education, Research and Practice
Authors: Bzymek Zbigniew M.
Published: August 2012

In the fast growing world economy engineering design and production plays a more and more important role almost every day. The only chance for the advanced western nations to maintain their leading technological positions during the course of the current century is to invest in technology and education. This may help to retain the position which, according to predictions, they may lose by 2035 [1]. One of the key ways of keeping their leading technological positions is to develop problem solving research and education to the degree to which all the potential of their national economy and technology would be used. In this paper some aspects of problem solving research and practice using an algorithmic method called BTIPS (Brief Theory of Inventive Problem Solving) are discussed. The importance of problem solving in engineering education is also stressed, and an example of a university course in the subject is discussed.
Molecular Dynamics Simulation of Thermal Conductivity and Viscosity of a Nanofluid: Effect of Nanoparticle Aggregation
Authors: Kang Hongbo , Zhang Yuwen , Yang Mo , Li Ling
Published: August 2012

Effect of nanoparticle aggregation on the thermal conductivity and viscosity of nanofluids is studied by molecular dynamics simulation in this work. Thermal conductivity and viscosity of the nanofluid are calculated using Green-Kubo method and results show that the nanoparticle aggregation induces a significant enhancement of thermal conductivity in nanofluid, while the increase of viscosity is moderate. The results also indicate that different configurations of the nanoparticle cluster result in different enhancements of thermal conductivity and increase of viscosity in the nanofluid. The differences between equilibrium molecular dynamics (EMD) approach and non-equilibrium molecular dynamics (NEMD) approach in obtaining the thermophysical properties of nanofluids are also discussed.
A Methodology to Conduct a Combined Heating and Power System Assessment and Feasibility Study for Industrial Manufacturing Facilities
Authors: Wheeley Chad , Mago Pedro J.
Published: August 2012

This paper considers combined heat and power (CHP) systems based on topping cycles only, in which electricity is generated by a prime mover and heat is then recovered from the exhaust and utilized to offset all or a portion of the facility’s process and/or space heating requirements.. The objective of this paper is to develop a methodology to perform a topping cycle CHP assessment and feasibility study for industrial manufacturing facilities. In order to determine the best and most viable option for the facility in question, the proposed methodology can be used to size different systems which utilize diverse technologies and fuel sources, perform an economic analysis of each proposed option, and then compare the benefits and setbacks of each type of CHP system considered. The calculations performed in the economic analysis will then provide a broad insight as to which proposed system will show the best payback if installed. Examples are presented in this paper that describe in detail the application of this methodology, from equipment selection and sizing through economic analyses and proposed system comparisons, which is recommended for use in order to determine the most economically feasible CHP system for an industrial manufacturing facility.
Computational Investigation of Tower Shadow Effects on Wind Turbines
Authors: Sescu Adrian , Andersen Brett , Afjeh Abdollah A.
Published: August 2012

In this paper, a Computational Fluid Dynamics (CFD) analysis of tower shadow effect associated with downwind configuration horizontal axis wind turbines (HAWT) is presented. This work is part of a large project focused on the design and installation of a multi-megawatt, downwind configuration, offshore HAWT in Lake Erie. The numerical tool is a dedicated commercial CFD solver, capable of performing accurate simulations in three dimensions, by solving the Navier-Stokes equations in turbulent regime. The tower shadow effect is analyzed by comparing results from the downwind configuration to results from the corresponding upwind configuration and free rotor.
Application of Immersed Boundary Method to Fluid, Structure and Electrostatics Interaction in MEMS
Authors: Mathur Sanjay , Sun Lin , Das Shankhadeep , Murthy Jayathi Y.
Published: August 2012

A comprehensive computational model is developed to study the dynamics of electrostatically-actuated micro-electromechanical system (MEMS) switches. The operation of the device involves a thin metal membrane in repeated contact with a substrate. The membrane is driven by an electrostatic force and is damped by the surrounding gas.. The coupled interaction of structure response, fluid dynamics and electrostatics must thus be solved. A unified computational framework based on the finite volume method (FVM) is developed to account for these mechanisms. The coupling between fluid, structure and electrostatics is achieved by employing the immersed boundary method (IBM). The advantage of the method is that it allows the fluid flow and electrostatics to be computed on a fixed background mesh while the solid body moves across it. Thus the effort of re-meshing is avoided, and the method potentially allows the simulation to proceed all the way to contact. A novel cell-marking scheme is applied to distinguish the solid region, fluid region and the immersed boundary (IB) region (i.e., the fluid and solid interface). Two-way interpolation is conducted on the IB region, allowing information exchange between fluid and solid. This includes the transfer of fluid and electrostatic forces to the solid surface and the solid position and velocity back to the fluid and electrostatics solution. A series of verification tests are carried out to establish the accuracy and performance of the method. The pull-in behavior of a cantilever switch and a frogleg device are predicted by the simulation.
Knowledge Based Methodology Supporting Interoperability Increase in Manufacture Domain
Authors: Mendonc¸a da Silva Joao P. , Cavaco Francisco , Sarraipa Joao , Jardim-Goncalves Ricardo
Published: August 2012

The formation of cooperation and collaboration alliances between several small organizations is proving, in multiple cases, to be more efficient and competitive by comparison with big companies. Manufacturing processes span nowadays across borders as result of the globalization markets pressure, thus research on manufacturing management has turned from an intra-enterprise to an inter-enterprise focus. Consequently there is a growing interest in electronic business (e-business) solutions to facilitate information sharing between organizations in the supply chain. However, due to the worldwide diversity of communities, a high number of knowledge representation elements, such as ontologies, which are not semantically coincident, have appeared representing the same segment of reality. Even operating in the same domain, enterprises do not understand each other, making the communication among various systems parties more difficult and sometimes impracticable. As a result there is a demand for intelligent solutions capable of reinforcing partnerships and collaborations between enterprises, which needs to be able to manage its maintenance dynamically. Authors propose the increase of Interoperability in the mechanical manufacturing domain by the use of a knowledge–based methodology able to build a reference ontology and to provide its maintenance through the system user’s feedback.
Optimum Vibration Design of Fiber Metal Laminated Panels by Particle Swarm Optimization Algorithm
Authors: Sadr Mohammad Homayoun , Ghashochi Bargh Hadi , Pourzand Hoofar , Karimi Masoud
Published: August 2012

This paper illustrates the application of the particle swarm optimization (PSO) algorithm to the lay-up design of symmetrically fiber metal laminated panels for maximization of fundamental frequency. The design variables are the number of layers, the fiber orientation angles of inner composite layers, edge conditions and panel length/width ratios. The classical laminated plate theory (CLPT) is used to calculate the natural frequencies and the fitness function is computed with a semi-analytical finite strip method which has been developed on the basis of full energy methods. The performance of the PSO is also compared with the simple genetic algorithm and shows the good efficiency of the PSO algorithm. To check the validity, the results are corroborated by comparing with some other stacking sequences.
Numerical Simulation of Truck Transportation
Authors: Mahajerin Enayat , Burgess Gary J.
Published: August 2012

Mathematical modeling and numerical simulation of truck transportation involve random vibration which requires statistical and spectrum analysis. To simulate truck transportation, the motion of a truck trailer is first recorded by mounting accelerometers on the floor of the trailer or on the framework of beams that support it. The floor accelerations in the vertical direction are sampled at regular intervals over the route that is to be simulated. This information is used to create a power spectral density plot (PSD) which contains frequency and amplitude information. The PSD plot is used to drive a vibration table with the product on it following the ASTM D4728 standard test guideline. To operate the table, we generate an acceleration input from the known PSD plot. We can also investigate the response of a product on the table by modeling the product as a mass-spring-damper system with known natural frequency and damping ratio. With the help of fatigue tools the results can be used in the damage assessment of the product during the truck ride.
Characterization of Air-Entrainment in a Plunging Water Jet System Using Image Processing: An Educational Approach
Authors: Molki Arman , Khezzar Lyes , Goharzadeh Afshin
Published: August 2012

This paper outlines a proposed experimental setup and image processing techniques using MATLAB for the characterization of the average dynamic behavior of the air/water mixture under the free surface of water penetrated by a plunging jet. The proposed setup focuses on the dynamics of air entrainment below the free surface and the identification of the major regimes related to the entrainment process of bubbles in water, namely: (a) no-entrainment, (b) incipient entrainment, (c) intermittent entrainment, and (d) continuous entrainment. The experimental setup allows students to observe the flow behavior below the free liquid surface and determine the penetration depth of the bubble plumes using image processing techniques in MATLAB. The focal point of the experiment is image analysis for qualitative and quantitative characterization of the bubble plume.
Modeling and Simulation of Mecano-Welding Process for Tubular Sections
Authors: Feng Zhengkun , Champliaud Henri
Published: August 2012

Mecano-welding process for tubular sections is proposed for manufacturing wind towers. It would be achieved by welding several cylindrical segments produced through roll bending. The first stage is the roll bending from a plate with cylindrical rolls. During the second stage the gas metal arc-welding is used to join the gap of the bent tubular section. The purpose of this research is to model and simulate the process under the well-known ANSYS and ANSYS/LS-DYNA environment, to analyze the residual stress distribution, particularly in the welded zone. This paper presents the modeling and simulation preparation for the second stage.
Development of Surface Tension Model Using Inter-Particle Force in Particle Method Based on Continuum Dynamics
Authors: Ishii Eiji , Sugii Taisuke
Published: August 2012

The particle method is a useful approach to simulate fluid flows within micro/nano spaces such as micro-electromechanical systems, nano-in-print processes, and head-disk interfaces of hard disk drives. Particle methods are based on continuum dynamics, and some studies have recently extended the scope of these methods to approaches within micro/nano spaces. Surface tension is a dominant force in the fluid flow within micro/nano spaces. However, surface-tension models used in the particle methods need to be improved to achieve more stable and accurate simulation. In the present study, we developed a new surface tension model for the particle method using inter-particle force to improve the stability and accuracy of simulation; the inter-particle force was given by the derivation of potential energy in space. The developed surface tension model was verified using simple benchmark tests: pressure in a round droplet and oscillation period of a square liquid-droplet. The predicted pressure in a round droplet agreed well with that given by the Young-Laplace equation, and the predicted oscillation period of a square droplet agreed well with that given by Lamb’s theory. The wall-adhesion was also verified at various contact angles; heights of droplets on the wall agreed well with those given theoretically. We found that our new surface tension model was useful for simulating fluid flow within micro/nano spaces for particle method.
Optimal Exhaust Tube Design for Diesel After-Treatment System
Authors: Lai F. C.
Published: August 2012

Diesel particulate filters (DPFs) are now considered a necessary and indispensable after-treatment system for reducing diesel soot to meet the future stringent regulations of diesel emissions. The present work is aimed at developing strategies for effective tube design to minimize the temperature drop (ΔT) between turbocharger outlet and diesel particulate inlet so as to improve the performance of DPF. Previous studies have shown that increasing heat retention in the operation of DPF improves fuel consumption by 5–7%. They have also shown that fuel economy can be improved by approximately 1% for every 4°C temperature reduction in downpipe. Exhaust tubes with diameter of 8.89 and 12.7 cm (3.5 and 5 in., respectively) with 2, 3, and 4 bends are examined in this study for their effects in the overall pressure drop. In addition, two types of insulations, thermolastic wrap and metal encapsulated with thermal conductivities of 0.133 and 0.024 W/m2·K respectively, are considered for their contribution to the overall temperature drop. It is expected that the results obtained will help in designing an optimal exhaust tube for a diesel after-treatment system.
Influence of Speed Bumps Design on Vehicle Safety
Authors: Garci´a-Pozuelo D. , Olmeda E. , Gauchi´a A. , Di´az V.
Published: August 2012

During a journey motor vehicles are forced to overcome different types of irregularities in the pavement. Such irregularities can be random or introduced for a specific purpose, such as asphalt protrusions and transversal bands of rubber, which have been installed into all sorts of avenues and roads open to traffic. Generally, these elements are included in a stretch of road to slow down the vehicle velocity at certain sites, such as pedestrian crossings. However, the influence of speed bumps installed shows other additional effects which must be studied to ensure the safety of vehicles and pedestrians. In some cases, it is found that, passing over ridges and transverse bands at a speed below the limit defined by law, the vehicle is damaged or the tires lose grip with the pavement, precluding any kind of braking or turning maneuvers. Such phenomena indicate that this element is not properly sized, or the placement is not appropriate, becoming counterproductive for traffic safety. In spite of the importance of these consecuences derivated from these elements they haven’t been studied deeply enough and there are very few paper about this subject. In order to analyze the actions generated by the overcome of these irregularities on the different components of the vehicle and its occupants, the problem has been studied not only using computer simulation but also by means of experimental testing on a real vehicle where accelerometers were installed in order to check the severity of the bumps. CarSimTM has been the simulation software used to calculate vehicle dynamic forces on the tires and suspension system and the accelerations and displacements that are applied to the vehicle. To characterize the behavior of a vehicle when is driven over one of these obstacles, it is necessary to study several parameters such as: speed, geometry and dimensions of the bump, and the type of vehicle and its suspension. From this information it is possible to establish a set of guidelines for the proper design and installation of speed bumps in different roads.
Step Response of a Single-Pass Crossflow Heat Exchanger With Variable Inlet Temperatures and Mass Flow Rates
Authors: Silaipillayarputhur Karthik , Idem Stephen A.
Published: August 2012

The step response of a single-pass crossflow heat exchanger with variable inlet temperatures and mass flow rates was determined. In every instance the energy balance equations were solved using an implicit central finite difference method. Numerical predictions were obtained for cases where both the minimum or maximum capacity rate fluids were subjected to step changes in inlet temperature, coupled with step mass flow rate changes of the fluids. Likewise performance calculations were conducted for heat exchangers operating initially at steady state, where step flow rate changes of the minimum and maximum capacity rate fluids were imposed in the absence of any temperature perturbations. Because of the storage of energy in the heat exchanger wall, and finite propagation times associated with the inlet perturbations, the outlet temperatures of both fluids do not respond instantaneously. A parametric study was conducted by varying the dimensionless parameters governing the transient response of the heat exchanger over a representative range of values.
High Temperature Damage of Ni-Base Superalloy Caused by the Change of Microtexture due to the Strain-Induced Anisotropic Diffusion of Component Elements
Authors: Miura Hideo , Suzuki Ken , Sasaki Yamato , Sano Tomohiro , Murata Naokazu
Published: August 2012

In order to assure the reliability of advanced gas turbine systems, it is very important to evaluate the damage of high temperature materials such as Ni-base superalloys under creep and fatigue conditions quantitatively. Since the micro texture of the gamma-prime (γ′) phase was found to vary during the creep damage process, it is possible, therefore, to evaluate the creep damage of this material quantitatively by measuring the change of the micro texture. The mechanism of the directional coarsening of γ′ phasesof Ni-base superalloy under uni-axial strain at high temperatures, which is called rafting, was analyzed by using molecular dynamics (MD) analysis. The stress-induced anisotropic diffusion of Al atoms perpendicular to the finely dispersed γ/γ′ interface in the superalloy was observed clearly in a Ni(001)/Ni3Al(001) interface structure. The stress-induced anisotropic diffusion was validated by experiment using the stacked thin films structures which consisted of the (001) face-centered cubic (FCC) interface. The reduction of the diffusion of Al atoms perpendicular to the interface is thus, effective for improving the creep and fatigue resistance of the alloy. It was also found by MD analysis that the dopant elements in the superalloy also affected the strain-induced diffusion of Al atoms. Both palladium and tantalum were effective elements which restrain Al atoms from moving around the interface under the applied stress, while titanium and tungsten accelerated the strain-induced anisotropic diffusion, and thus, the rafting phenomenon.