bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Coupled Whirling and Tool Geometry on Machining Dynamics
Authors: Dassanayake Achala V. , Suh C. Steve
Published: October 2013

Turning dynamics is investigated using a 3D model that allows for simultaneous workpiece-tool deflections in response to the exertion of nonlinear regenerative force. The workpiece is modeled as a system of three rotors, namely, unmachined, being machined and machined, connected by a flexible shaft. Such a configuration enables the workpiece motion relative to the tool and tool motion relative to the machining surface to be three-dimensionally established as functions of spindle speed, instantaneous depth-of-cut, material removal rate and whirling. The equations of motion for the model are coupled through the nonlinear cutting force. The model is explored by considering the tool geometry. Different stages of stability for the workpiece and the tool subject to the same cutting conditions are studied.
A Novel Compliant Fixation Plate for Bone Fractures
Authors: Kim Kwangwon , Ju Jaehyung , Kim Doo-Man
Published: October 2013

Rigid bone fixation plates made of stainless steel or a titanium alloy are used as supplemental support structures when a fracture occurs in a long bone. These fixation plates are about an order of magnitude higher in elastic modulus than that of cortical bones, which may cause high interface stress between the fixation plate and the bone. Moreover, when they are used for a bone fracture in a child, they may prevent bone growth due to their high stiffness in the longitudinal direction. In this study, we suggest a novel fixation plate that controls for the stiffness and elastic elongation in the uni-axial loadings, namely tension and compression. Using a flexure based compliant mechanism and cellular structures, uni-axial load-deflection curves are generated in tensile and compression loads. A commercial finite element (FE) code, ABAQUS, is used for a parametric study of the geometric effect of the cellular structures on stiffness and elastic elongation. Performance of the designed fixation plate is validated by an FE analysis for bone tension and compression under a contact condition between the bone and fixation plate.
Explicit Dynamic Simulation of Impact in Cylindrical Lithium-Ion Batteries
Authors: Avdeev Ilya V. , Gilaki Mehdi
Published: October 2013

High-voltage lithium-ion batteries are increasingly used in electric and hybrid-electric vehicles. Due to a risk of being in an accident, these energy storage systems should be analyzed thoroughly so that the risk of failure or serious damage during accidents is minimized. In this research a three-dimensional finite element simulation of a cylindrical battery cell is performed to study the behavior of the cell under various loading conditions. Li-Ion batteries consist of very thin layers of anodes, cathodes and separators that are packed into a cylindrical-spiral shape. This non-homogeneity nature of the battery cells makes the finite element explicit model very complicated. In this study, a homogenized 3-D model of the cell has been developed that is more suitable for explicit high-strain-rate transient analyses. Another model using layered solid or thick shell elements was generated. For the latter, partially two-phased homogenized material properties were used. Three different configurations are considered to analyze the battery packs: an indentation test with a rigid tube, longitudinal crushing between rigid plates, and transverse crushing. Results from these numerical simulations were consistent for models with thick shell elements and homogenized models.
3D Numerical Investigation of Effect of Milling Process Parameters on High Speed Milling of Ti-Al6-V4
Authors: Ma J. , Lei Shuting , Lu Huaqi
Published: October 2013

Titanium alloys are widely used in aerospace industry owing to excellent mechanical properties. While because of high chemical reactivity and low thermal conductivity, titanium alloys are classified as hard-to-cut materials. In this paper, Finite Element Method (FEM) is employed to conduct numerical investigation in the effects of milling process parameters (milling speeds, feed per tooth, and axial depth of cut) on three-dimensional (3D) high speed milling of Titanium alloy (Ti-6Al-4V). The tool material used is Carbide and Johnson-Cook plastic model is employed to model the workpiece due to its capability of modeling large strains, high strain rates, and temperature dependent visco-plasticity. Different milling speeds, feed per tooth, and axial depth of cut are used to explore the effects of the milling process parameters on the cutting temperature, cutting forces, and power required for machining. This model provides fundamental understanding of cutting mechanics of the 3D high speed milling of Titanium alloy (Ti-6Al-4V).
Effect of Partial 3-Dimensional Pin Fin Geometry for Heat Transfer Enhancement in High Aspect Ratio Channels
Authors: Pandit Jaideep , Dove Megan , Ekkad Srinath V. , Huxtable Scott
Published: October 2013

The efficiency of a TEG (Thermoelectric Generator) may be thought of as the ratio of the power output to the heat input at the hot junction. This ratio is governed by the laws of thermodynamics and cannot thus exceed the Carnot efficiency. It follows that the greater the difference between the hot and cold side temperatures, the greater the efficiency of the TEG. Heat transfer enhancement measurements with 3-Dimensional partial pin-fin arrays of varying shapes on a flat plate are presented. The fin height is fixed at 15% of channel height. The hydraulic diameter and configuration of the fins are chosen based on existing literature. The study is carried out at various Reynolds numbers based on full channel height. The shapes studied are circular, semi-circular, triangular, hexagonal and diamond shaped. These shapes are compared against a baseline case without fins. The experiment uses the transient liquid crystal (TLC) method to calculate the heat transfer coefficient on the test surface. The data shows that diamond shaped fins provide the highest turbulent mixing downstream of the pins leading to the highest heat transfer coefficients.
Thermal Accommodation Coefficients for Time-Resolved Laser-Induced Incandescence Sizing of Metal Nanoparticles in Monotomic Gases
Authors: Sipkens T. A. , Daun K. J. , Titantah J. T. , Karttunen M.
Published: October 2013

There is recent interest in adapting time-resolved laser-induced incandescence (TiRE-LII) to measure aerosolized metal nanoparticles, which requires knowledge of the thermal accommodation coefficient between the gas and the laser-energized particle. This paper presents accommodation coefficients for various metal particles in monatomic gases derived using molecular dynamics (MD). A comparative analysis of different gas/metal systems reveals a fundamental relationship between the thermal accommodation coefficient and the potential well depth. Finally, MD derived accommodation coefficients are used, for the first time, to recover particle sizes from TiRe-LII measurements made on molybdenum nanoparticles in helium and argon atmospheres.
3D FEM Investigation of the Effects of Nose Radius and Edge Radius on Turning of AISI 4140
Authors: Ma J. , Yong Yaowei , Lei Shuting
Published: October 2013

In this paper, FEM is employed to investigate the effects of nose radius and edge radius on the turning of AISI4140. The tool material used is Carbide and Johnson-Cook plastic model is employed to model the workpiece due to its capability of modeling large strains, high strain rates, and temperature dependent visco-plasticity. Different nose radii and edge radii are used to explore the effects of the nose radius and edge radius on the machining temperature, cutting forces, and power. This model provides a fundamental understanding of cutting mechanics of the turning operation of AISI 4140.
Performance Analysis and Design Optimization of 5R Planar Parallel Robots
Authors: Huang Ming Z.
Published: October 2013

This paper addresses the dimension synthesis and optimization of planar parallel robots. The design problem for parallel robots in general is much more complex than their serial counterparts, due to the strong dependence of geometric parameters and their performances. In dimension synthesis, typical performance characteristics that may be considered to evaluate the fitness of a design include workspace, manipulability, velocity, stiffness, and payload. A case study on optimal design for both workspace and manipulability had been presented previously for a specific class of planar parallel robots with 5R joints. This paper extends the design optimization study to include the remainders for the same class of 2-dof robots. Analyses of individual performance characteristics relative to the velocity, stiffness, and payload properties will be presented first. A simple and yet effective parameter-variation-based method will be demonstrated to obtain various optimal design solutions corresponding to those characteristics respectively.
Heat Transfer Model and Quantitative Analysis of Deep Tissue Injury
Authors: Chanmugam Arjun , Bhargava Akanksha , Herman Cila
Published: October 2013

Deep tissue injuries (DTI) are serious lesions which may develop in deep tissue layers as a result of sustained tissue loading or ischemic injury. These lesions may not become visible on the skin surface until the injury reaches an advanced stage making their early detection a challenging task. Early diagnosis leading to early treatment mitigates the progression of lesion and remains one of the priorities in management. The aim of this study is to examine skin surface temperature distributions of damaged tissue and develop criteria for the detection of incipient DTIs. A multilayer quantitative heat transfer model of the skin tissue was developed using a finite element based software COMSOL Multiphysics. Thermal response of the skin surface was computed during deep tissue inflammation and deep tissue ischemia and then compared with that of healthy tissue. In the presence of a DTI, an increase of about 0.5°C in skin surface temperatures was noticed during initial phase of deep tissue inflammation, which was followed by a surface temperature decrease of about 0.2°C corresponding to persistent deep tissue ischemia. These temperature differences are large enough to be detected by thermographic imaging. This study, therefore, also enhances the understanding of the previously detected thermographic quantitative changes associated with DTIs.
Design and Fabrication of Rock-Based Micromodel
Authors: Park Daniel S. , Bou-Mikael Saade , King Sean , Thompson Karsten E. , Willson Clinton S. , Nikitopoulos Dimitris E.
Published: October 2013

A rock-based micromodel was designed using depth averaging with Boise rock digital images obtained from the X-ray micro-computed tomography. Design optimization of 2.5D micromodels was carried out using computational fluid dynamics (CFD) simulations through error analysis of dynamic flow parameters (velocities and permeability), which showed the close dynamic flow match between the actual 3D rock and the optimized 2.5D micromodel. Multiple numbers of polymer micromodels were microfabricated via micromilling of a brass mold insert and hot embossing in polymethylmethacrylate (PMMA). The design optimization and the replication-based microfabrication processes enabled the realistic pore geometry generation, which conforms to the pore dimensions of an actual rock sample but with coarser features in a polymer microfluidic platform. The microfabricated PMMA micromodel was used for fluidic characterization with nanoparticles to compare the flow patterns between the designed micromodel and the microfabricated micromodel. Particle motion paths observed in the particle experiments showed the consistent similarity of stream-traces from the CFD simulations of the designed 2.5D micromodel. Further fluidic investigation on the 2.5D rock-based micromodels will provide better understanding on fluid transport mechanism in porous media.
Radiative Heat Transfer in High-Pressure Laminar Hydrogen-Air Diffusion Flames Using Spherical Harmonics and K-Distributions
Authors: Cai Jian , Lei Shenghui , Dasgupta Adhiraj , Modest Michael F. , Haworth Dan C.
Published: October 2013

Radiative heat transfer is studied numerically for high-pressure laminar H2-air jet diffusion flames, with pressure ranging from 1 to 30 bar. Water vapor is assumed to be the only radiatively participating species. A full spectrum k-distribution spectral model is used. Narrowband k-distributions of water vapor are calculated and databased from the HITEMP 2010 database, which claims to retain accuracy up to 4000K. The full-spectrum k-distributions are assembled from their narrowband counterparts to yield high accuracy with little additional computational cost. The radiative transfer equation (RTE) is solved using various spherical harmonics methods, such as P1, simplified P3 (SP3) and simplified P5 (SP5). The resulting partial differential equations as well as other transport equations in the laminar diffusion flames are discretized with the finite-volume method in OpenFOAM. Differential diffusion effects which are important in laminar hydrogen flames are also included in the scalar transport equations. It was found that peak flame temperature becomes less sensitive to radiation at higher pressure, and that radiation causes cooling in the downstream region. Differences between the three spherical harmonics RTE solver were found negligible below 5 bar.
Developing Resource Consumption Insights From Campus-Scale Water Monitoring Infrastructures
Authors: Lyon Geoff , Shah Amip , McReynolds Alan
Published: October 2013

Water consumption at many commercial campuses is a significant portion of resource expenditure, often with limited or no visibility into the individual branch or point of use locations, all of which summate to provide utility based reporting and invoicing, mostly on a monthly basis.

In this paper, we present a case study where a commercial campus’ water distribution system is being instrumented to obtain a more granular measure of water usage. Measurement granularity is improved both in the time domain, transitioning from monthly to hourly or more frequent reporting, and in the spatial domain with all major end loads and significant branch loads being classified or monitored. Specifically, additional instrumentation is deployed in two distinct phases. The first phase added wireless transducers to the existing utility installed mechanical meters, enabling them to transmit consumption data every quarter hour. The second phase will instrument existing branch flow meters and also insert new flow meters to certain end-point loads and sub-branches. This will enable point or clustered data polling on the order of every few seconds. We also obtain additional information by polling an existing HVAC building management system for water related points of interest.

We find that the collection and storage of granular water consumption information has the potential to create a detailed demand-side mapping of water usage on campus; providing data with significantly shortened time periods compared to the use of utility billing alone. We use this information to obtain hourly and daily consumption summaries at the site level and for specific end-load devices. From these results, we have created a hybrid consumption estimation of water consumption at the campus level, which contains a mixture of surveyed estimations and dynamic readings. This model provides improved accuracy and insights when compared to static site survey estimations. Due to the age and complexity of the site, primarily a result of numerous engineering changes over the site’s 60 year lifespan and a lack of detailed historical documentation, further work is ongoing to determine which additional endpoint loads or branched sub-sections we will instrument. We plan to use these additional data points to refine our water distribution model; hoping to accurately map individual buildings, floors and functional areas over time.

At present, our site level instrumentation has been beneficial in revealing a number of insights regarding unexpected consumption events, most of which were attributed to scheduled maintenance activities. The ongoing monitoring of individual end-point loads has also highlighted areas of significant demand, which could be prioritized for conservation initiatives, and has shown where systemic adjustments could reduce demand peaking and flatten the flow requirements our campus places on the supplying utility.
Office of the Future: Advanced Lighting Control Strategies
Authors: James Brian , Delaney Paul , Avery Doug
Published: October 2013

The Office of the Future (OTF) program is a new energy efficiency approach supported by a consortium of some of the nation’s largest and most progressive energy utilities. OTF targets existing multi-tenant commercial office buildings with packages of advanced energy efficiency strategies that can be applied at the tenant level for building owners. The overall goal is to assemble technical guidelines to office renovation projects that specify performance requirements for different attributes of the office (lighting, plug loads, etc.) and whole building that result in 25% and 50% savings better than code.

Three pilot projects were conducted:

1. Executive office space

2. Open area office space

3. Office space with five private offices, a conference room, lobby, kitchen, and corridor

The executive offices provided an opportunity to measure energy use in a 1,360 square-meters (m2) office and to undertake a relighting project that met the architectural, aesthetic, and functional demands of the space while employing current energy-efficient products and design techniques.

The open area office space consisted of 745 m2 of primarily cubicle office space — half of the 12th floor of a federal building in Santa Monica, CA. The project was highly representative of the challenges and complications faced in retrofit projects in everyday office buildings.

The office space with private offices involved renovating the lighting and lighting controls in a 147 m2 office space in the 41,156 m2 building, and summarized the performance of the lighting design in accordance with the OTF Technical Guidelines. In addition, this project included details regarding the pre- and post-lighting systems and controls, compares the actual metered power and energy performance of the 2008 Title 24 code baseline, presents the code calculation basis, and reveals some of the complexities associated with this approach.

These pilot projects had three primary goals: 1) examine the performance characteristics of highly-controlled lighting systems in a real office environment compared to existing lighting and applicable codes, 2) monitor plug load energy use, and 3) provide measured and technical data back to OTF consortium members to inform the OTF process.

The measured results of the open area office space project revealed that a high-performance lighting design with controls delivers savings considerably beyond code-calculated estimates. In fact, results show that during daytime occupied hours, the average site usage is 43% less power than code calculations. The new system reduced the connected load by 56%. Similar results were found for the other two pilot projects.
An Approach to Rating of Vehicle Climate Controls in Hybrid and Electric Driven Vehicles for Energy Efficiency
Authors: Brezger Friedrich , Albers Albert
Published: October 2013

As part of the auxiliary components, climate controls and heating devices do have a relatively high energy consumption maintaining the comfort in the passenger cabin, which is a problem in the development of hybrid and especially electric vehicles. Hence, these vehicles have high potentials in optimizing the climate control. Several concepts of optimizing energy consumption are well known, such as insulation, glasses with better transmission coefficients, pre-conditioning or heat exchanger of outlet air. The efforts, the complexity, the installation space and the weight of these implementations are increasing. The weight of these additional components has an impact on the energy consumption of the vehicle.

In order to evaluate the interdependencies between the direct energy consumption of possible solutions and their additional effects in early stages of product development, this paper introduces one possible approach for rating. Using the example of a heat pump which will be used for heating and cooling the passenger’s cabin, the applicable modeling in Matlab/Simulink will be demonstrated. One part of this implementation is a comparison of the approach based on Frank [Gro10] and another approach based on Nitz and Hucho [Gro10] in aspects of a sensitivity study. Furthermore, the impact of different insulation methods (glass transmission, insulation of the carriage) at extreme and average environmental boundary conditions as well as the changed weight and installation space is investigated. Therefore an environmental model is introduced which takes day time, season as well as GPS data into account. Target of this investigation is defining the minimum necessary power of a heat pump in the passenger cabin of a commercial vehicle with the smallest possible installation space and increase in weight. By modeling and analyzing this example scenario, sustainable values are derived in order to enable a cost-utility analysis of different vehicles in their respective market segments and the chosen solution of climate control.
Development of the Strength Evaluation Method for Body of Mining Dump Truck Under Actual Operations
Authors: Kita Yasuki , Satou Takayuki , Kitaguchi Atsushi , Sasaki Takashi
Published: October 2013

The prediction method of the experimental stress wave at the welded joints of the body under actual operations was developed, and the strength evaluation flow based on the method was proposed.

We conducted running tests using a dump truck prototype, the EH3500ACII, as an experimental approach. The high accelerations in longitudinal, vertical, and lateral directions were measured for a sudden stop, bump override and sharp turn test, respectively. The tendencies of the stress waveforms at the welded joints in each running test are in good agreement with those of the acceleration waveforms.

The distinct element (DE) and finite element (FE) methods were used to predict the experimental stress waves. First, the pressure loads of soil were analyzed using DE method. Kanto loam (Japanese soil) was modeled using a large number of particles, and filled a container modeled using rigid plates to form a shape similar to that of actual loads. The soil pressure distributions were formulated with a variety of acceleration loads. Next, the obtained load pressures were applied to the FE model as the load conditions. The stresses at the evaluation points were calculated under a 1G acceleration in the vertical, lateral, and longitudinal directions, respectively. Finally, those stress results and the measured time series acceleration data were multiplied, and the stress waveforms under running conditions were predicted by using a linear superposition method.

When the analytical stresses were compared with the experimental results, the tendencies of the analytical stress variations corresponded well with those of the experimental stress waveforms. On the other hand, the analytical stresses were smaller than the actual experimental values. This was because the weld geometries were not modeled in FE model, and the stress concentrations on the weld toes were not precisely estimated.

The strength evaluation flow was developed by using the soil pressure distribution formulated using the DE analysis, the database of the time series acceleration data obtained from the running tests, the ratio of the stress ranges of the experiment and that of the analysis, Kstress_ratio, and the strength criteria for welded joints. It is possible to evaluate the durability of a new structure model in a short period of time by using this evaluation flow.
System-Level Design for Liquid Cooled Chiller-Less Data Center
Authors: Parida Pritish R. , Chainer Timothy , Iyengar Madhusudan , David Milnes , Schultz Mark , Gaynes Michael , Kamath Vinod , Kochuparambil Bejoy , Simons Robert , Schmidt Roger
Published: October 2013

In 2010, data center power usage amounted to 2% of total US energy consumption [1]. Approximately 25% of the energy consumed is used for IT cooling, which consists of facility refrigeration equipment used to provide computer room air conditioning [2]. As part of a US Department of Energy cost shared grant, a data center test facility was designed and constructed with the goal to demonstrate the potential to reduce IT cooling energy usage to less than 5% of the total IT and facilities energy usage by utilizing warm liquid cooling of the electronics rack. A system thermodynamic model was developed for this liquid cooled chiller-less data center design using theory, numerical simulations and manufacturer’s data sheets. The model was used for the design selection of data center level cooling infrastructure and of server liquid cooling components and for performance estimation of the liquid cooled chiller-less data center design. The system-level model was validated against experimental data and was used to predict the system performance in different geographies.
Un-Shocked High Amplitude Standing Waves in Wave-Shaped Resonators
Authors: Antao Dion Savio , Farouk Bakhtier
Published: October 2013

A numerical study of non-linear, high amplitude standing waves in non-cylindrical circular resonators is reported here. These waves are shock-less and can generate peak acoustic overpressures that can exceed the ambient pressure by three/four times its nominal value. A high fidelity compressible computational fluid dynamic model is used to simulate the phenomena in cylindrical and arbitrarily shaped axisymmetric resonators. A right circular cylinder and frustum of cone are the two geometries studied. The model is validated using past numerical and experimental results of standing waves in cylindrical resonators. The non-linear nature of the harmonic response of the frustum of cone resonator system is investigated for two different working fluids (carbon dioxide and argon) operating at various values of piston amplitude. The high amplitude non-linear oscillations demonstrated can be used as a prime mover in a variety of applications including thermoacoustic cryocooling.
Finite Element Simulations of Monolithic Plates for the Conversion of High Performance Research and Test Reactors: NBSR, MITR, MURR and AFIP
Authors: Ozaltun Hakan , Miller Samuel J.
Published: October 2013

This article presents evaluation of the stress-strain characteristics of U10Mo alloy based monolithic fuel plates for the conversion of high power research and test reactors. Monolithic plate-type fuel is a new fuel form being developed to achieve higher uranium densities within the reactor core to allow the use of low-enriched uranium fuel in high performance reactors. For this work, irradiation behavior of four different reactor plates (NBSR, MURR, MITR and AFIP plates) with different foil and cladding geometries were benchmarked against each other. For each plate, three distinct cases were considered: (1) fabrication induced residual stresses (2) thermal cycling of fabricated plates and finally (3) mechanical behavior under proposed irradiation conditions. Given that the temperatures approach the melting point of the cladding during the fabrication and thermal cycling, high temperature material properties were incorporated to improve accuracy. Residual stress fields due to the fabrication process (Hot Isostatic Pressing) were computed first. Solutions of fabrication simulations were used as initial states for the irradiation and thermal cycling simulations. For the thermal cycling simulation, an elasto-plastic material model with thermal creep was used. The transient irradiation behavior was formulated by a fully coupled thermal-structural interaction. Temperature fields on the plates were used to compute the thermal stresses. Volumetric swelling and irradiation creep of the foil were considered. The irradiation analysis showed that the stresses evolve rapidly in the reactor. It was found that the stress field of the fuel elements is dependent on the plate geometry, especially the foil thickness. Furthermore, the foil-cladding thickness ratio is the determining factor for the mechanical behavior. The compressive stresses of the foil are reduced with an increasing foil-cladding thickness ratio. The cladding deformation becomes severe for the plates with thicker foils.
Project Based Learning in First Year, First Semester of Industrial Engineering and Management: Some Results
Authors: Alves Anabela C. , Moreira Francisco , Lima Rui , Sousa Rui , Dinis-Carvalho José , Mesquita Diana , Fernandes Sandra , van Hattum-Janssen Natascha
Published: October 2013

The innovative learning methodology Project-based learning (PBL) has been functioning in the first semester of the first year of the Master Degree in Industrial Engineering and Management (IEM) at University of Minho, Portugal, since 2004_2005. This methodology was implemented by a team of teachers from the Department of Production and Systems of the Engineering School just before the Bologna process was adopted in Portugal. The process required substantial changes in the teaching/learning methods and methodologies and had a significant impact on students’ learning and motivation. The team of IEM teachers designed a full semester project based on the contents of four project-supporting courses (PSC), and formed a coordination team involving PSC lecturers, tutors and educational researchers. The latter aimed to accompany students’ teams, assess the learning process and evaluate the PBL experience at IEM. After nine editions of PBL in the first year, the IEM curricular structure has been reformulated to include a semester-wide project course in the first semester, recognizing PBL as a distinct part of the curriculum. It is therefore time to reflect on the past experiences and the merits of the PBL experiences. After presenting the overview of PBL based on the IEM specific context, its merit will be discussed through the analysis of surveys results and workshops organized at the end of last three PBL editions. This learning approach has put many challenges to the coordination team, brought discussion and triggered research that supported PBL along the way.
A Comparative Study of the Human Body Finite Element Model Under Blast Loadings
Authors: Tan X. G. , Kannan R. , Przekwas Andrzej J.
Published: October 2013

Until today the modeling of human body biomechanics poses many great challenges because of the complex geometry and the substantial heterogeneity of human body. We developed a detailed human body finite element model in which the human body is represented realistically in both the geometry and the material properties. The model includes the detailed head (face, skull, brain, and spinal cord), the skeleton, and air cavities (including the lung). Hence it can be used to accurately acquire the stress wave propagation in the human body under various loading conditions. The blast loading on the human surface was generated from the simulated C4 blast explosions, via a novel combination of 1-D and 3-D numerical formulations. We used the explicit finite element solver in the multi-physics code CoBi for the human body biomechanics. This is capable of solving the resulting large system containing millions of unknowns in an extremely scalable fashion. The meshes generated for these simulations are of good quality. This enables us to employ relatively large time step sizes, without resorting to the artificial time scaling treatment. In order to study the human body dynamic response under the blast loading, we also developed an interface to apply the blast pressure loading on the external human body surface. These newly developed models were used to conduct parametric simulations to find out the brain biomechanical response when the blasts impact the human body. Under the same blast loading we also show the differences of brain response when having different material properties for the skeleton, the existence of other body parts such as torso.
Characterization and Combustion Performance of Corn Oil-Based Biofuel Blends
Authors: Savant Gautam , Alvarado Jorge L. , Annamalai Kaylan , Capareda Sergio
Published: October 2013

A study has been undertaken to understand the effects of blending high-viscosity fresh and used corn oils with diesel and jet fuel mixed with butanol and ethanol on combustion emissions such as NOX and CO. Several corn oil-based blends were formulated, characterized, and compared to understand the effect of composition on viscosity, fuel stability and energy content. The formulated corn oil blends were combusted in a 30 kW modified combustion chamber to determine the corresponding NOx and CO emission levels. Used corn oil was made and characterized by quantifying its total polar material (TPM), iodine value, free fatty acid content, and peroxide value. The combustion experiments were conducted at a constant heat output of 19 kW to observe and study the effects of equivalence ratio, swirl number, and fuel composition on emissions. Used corn oil blends exhibited better combustion performance than fresh corn oil blends, due in part to the higher unsaturation levels in fresh corn oil. NOx emissions for used corn oil increased with swirl number. The combustion experiments also revealed that higher amount of diesel (lower amount of corn oil) results in higher NOx emissions. All corn oil-based blends showed a generally decreasing carbon monoxide (CO) trend at both swirl numbers at very lean conditions. The results also indicate that used corn oil can be combusted efficiently when mixed with diesel or jet fuel resulting in low NOx levels.
On the Computational Modeling of Unfluidized and Fluidized Bed Dynamics
Authors: Teaters Lindsey C. , Battaglia Francine
Published: October 2013

Two factors of great importance when considering gas-solid fluidized bed dynamics are pressure drop and void fraction, which is the volume fraction of the gas phase. It is, of course, possible to obtain pressure drop and void fraction data through experimentation, but this tends to be costly and time consuming. It is much preferable to be able to efficiently computationally model fluidized bed dynamics. In the present work, ANSYS FLUENT is used to simulate fluidized bed dynamics using an Eulerian-Eulerian multiphase flow model. By comparing the simulations using FLUENT to experimental data as well as to data from other fluidized bed codes such as Multiphase Flow with Interphase eXchanges (MFIX), it is possible to show the strengths and limitations of FLUENT with respect to multiphase flow modeling. The simulations described herein will focus on modeling of beds in the unfluidized regime, where the inlet gas velocity is less than the minimum fluidization velocity, and will deem to shed some light on the discrepancies between experimental data and FLUENT results. In addition, this paper will also include comparisons between experimental data and simulation data in the fluidized regime based on void fraction contours and profiles.
A Newton-Krylov Algorithm for High-Order Finite Element Computation of Heat Conduction Problems
Authors: Nejat Amir , Mirzakhalili Ehsan
Published: October 2013

The solution of a high-order conduction problem with different orders of accuracy has been investigated in this paper. The high-order solutions are obtained using Discontinuous Galerkin (DG) finite element method. The problem is solved by implicit Newton-Krylov method for different accuracy orders. The convergence of the implicit technique is investigated in terms of the CPU time. The results show the possibility of achieving an accurate and smooth solution over a coarse mesh when the higher-order discretization is employed.
Nonlinear Parametric Instability of Functionally Graded Rectangular Plates in Thermal Environments
Authors: Alijani F. , Amabili M.
Published: October 2013

Geometrically nonlinear parametric instability of functionally graded (FG) rectangular plates in thermal environments is investigated via multi-modal energy approach. Nonlinear higher-order shear deformation theory is used and the nonlinear response to in-plane static and harmonic excitation in the frequency neighbourhood of twice the fundamental frequency is investigated. The boundary conditions are assumed to be simply supported movable. The plate displacements and rotations are expanded in terms of double series trigonometric functions and Lagrange equations are used to reduce the energy functional to a system of infinite nonlinear ordinary differential equations with time varying coefficients, and quadratic and cubic nonlinearities. In order to obtain the complete dynamic scenario, numerical analyses are carried out by means of pseudo arc length continuation and collocation technique to obtain frequency-amplitude and force-amplitude relations in the presence of temperature variation in the thickness direction. The effect of volume fraction exponent as well as temperature variation on the on-set of instability for both static and periodic in-plane excitation are fully discussed and the post-critical nonlinear responses are obtained.
Effect of Roughness in Lock Exchange Density Currents
Authors: Chowdhury Raghib , Bhaganagar Kiran
Published: October 2013

A preliminary analysis has been performed to understand the effect of surface roughness height on the evolution of the density currents generated in lock-exchange mechanism. The results have revealed density currents over rough wall travel at a lower speed compared to those over smooth wall. Further, a regression analysis has revealed that the maximum front velocity varies as e−k, where k is the height of the surface roughness.
Enhanced Liquid Jet Impingement Boiling
Authors: Zhao Zenghui , Woodcock Corey , Peles Yoav , Jensen Michael K.
Published: October 2013

In a previous study, it was shown that water jet impinging on structured-porous surface is a highly efficient way in dissipating high heat flux with small surface temperature increase. As an extension, this work studies jet impingement boiling on a plain surface and a porous surface using HFE-7000 as the working fluid. The effects of jet Reynolds number and jet inlet subcooling on heat transfer performance were explored with atmospheric experiments. The results show that, for plain surface, neither flow rate nor subcooling has significant effects on heat transfer performance when boiling is fully established; for porous surface, the effects of subcooling and jet Reynolds are more pronounced. In addition, CHF was reached during all experiments. Correlation was developed that can satisfactorily predict CHF for HFE-7000 jet impingement on plain copper surface.
Stabilized Finite Element Method for Solids With Large Gradient Mechanical Properties
Authors: Lorin Samuel , Sandboge Robert
Published: October 2013

Many polymers exhibit mechanical properties that vary greatly with temperature. The stress-strain relationships may include a tensile modulus that for certain temperature ranges decreases drastically. For instance, linear amorphous polymers have glassy-transition-rubbery-flow regions where the Young’s modulus is nearly constant in the glassy and rubbery plateau, but decreases rapidly with temperature in the transition and flow regions. To predict displacement of solids the finite element method (FEM) is often used. However, for structural problem with large variations of material properties the stability of the solution is affected negatively. In this work we formulate a sub-scale finite element formulation for thermal plasticity problems based on differential inclusions of elliptic and parabolic type.
Modelling and Simulation of the Hand-Arm-System During Impact Influences
Authors: Matthiesen Sven , Schäfer Tobias , Mangold Sebastian
Published: October 2013

Most common models of hand-arm systems describe the mechanical response by low accelerations and short movements. The focus of this paper is on impacts (over 4.000 m/s2) to the human hand-arm system, in this case caused by a bolt setting device. To develop an accurate model of the hand-arm system, the force needed to be measured without to influence the interaction. Because of the very short time period it is not possible to measure the reaction force directly. To investigate the effects of different operators on the behavior of the power tool, a two-degree-of-freedom model of hand-arm-systems is developed, to predict mechanical interactions of the hand-arm-system with the power tool. Inputs for this simulation model are movement, velocity and acceleration. The motion of the device in the heavy impact phase is tracked by a high-speed camera and time-synchronized acceleration sensors. Based on this data, a robust and easy model of a hand-arm system is presented.
Nanoparticle Redistribution During Magnetic Nanoparticle Hyperthermia: Multi-Physics Porous Medium Model Analyses
Authors: Attaluri Anilchandra , Ivkov Robert , Ma Ronghui , Zhu Liang
Published: October 2013

A coupled theoretical framework comprising a suspension of nanoparticles transport in porous media model and a heat transfer model is developed to address nanoparticle redistribution during heating. Nanoparticle redistribution in biological tissues during magnetic nanoparticle hyperthermia is described by a multi-physics model that consists of five major components: (a) a fully saturated porous media model for fluid flow through tissue; (b) nanoparticle convection and diffusion; (c) heat transfer model based on heat generation by local nanoparticle concentration; (d) a model to predict tissue thermal damage and corresponding change to the porous structure; and (e) a nanoparticle redistribution model based on the dynamic porosity and diffusion diffusivity. The integrated model has been used to predict the structural damage in porous tumors and its effect on nanoparticle-induced heating in tumors. Thermal damage in the vicinity of the tumor center that is predicted by the Arrhenius equation increases from 14% with 10 minutes of heating to almost 99% after 20 minutes. It then induces an increased tumor porosity that increases nanoparticle diffusivity by seven-fold. The model predicts thermal damage induced by nanoparticle redistribution increases by 20% in the radius of the spherical tissue region containing nanoparticles. The developed model has demonstrated the feasibility of enhancing nanoparticle dispersion from injection sites using targeted thermal damage.
Autonomous Unmanned Aerial Vehicle System for Controlling Pest Bird Population in Vineyards
Authors: Grimm Brian A. , Lahneman Brooke A. , Cathcart Peter B. , Elgin Robert C. , Meshnik Greg L. , Parmigiani John P.
Published: October 2013

Pest birds have long been a significant source of crop loss for grape growers, especially during the critical weeks leading up to harvest when grape sugar levels are high. In Oregon’s Willamette Valley, vineyards have seen a marked increase in crop loss in the last few years despite widespread use of intrusive gas cannons/shotguns and expensive netting systems. In order to deter this pest bird population, we have created an Unmanned Aerial Vehicle (UAV) package capable of autonomous flight, which incorporates common pest bird scare tactics into this dynamic platform. The system has been designed to launch, complete its mission waypoints, and land completely under autonomous control. By using this autonomous guidance system, we are able to employ visual, auditory, and predator mimicry pest bird control techniques in such a way as to discourage habituation. While radio controlled UAVs have been used for bird control in airport settings for many years, these systems require a trained operator to constantly guide the aircraft. The autonomous UAV system was designed for operation by an existing vineyard employee with minimal training. To capture widely accepted pest bird control techniques and management culture of Willamette Valley vineyards and gain information for design, implementation, and industry acceptance of this UAV project, we surveyed the owners of 225 local vineyards. Survey results indicated that vineyard owners are open to implementing innovative pest bird control methods that do not affect the terroir of their vineyards and that could replace the use of netting, which they do not view favorably despite its being the most effective pest bird control method to date. Results also indicated that pest birds are most damaging to a vineyard’s perimeter and that many vineyards employ someone to patrol this perimeter with a shotgun loaded with cracker shells. The UAV system is able to traverse the airspace above this perimeter without interfering with neighboring homes or beneficial predators in the area. By using proven pest bird control methods in an autonomous UAV system, we designed a device that brings an innovative solution to vineyard owners.
Preliminary Study on the Heat Transfer and Fluid Flow in Formed, Lap-Wound End Windings of Electric Machinery
Authors: Mancuso Thomas , Mukherjee Abhijit
Published: October 2013

Thermal analysis is a critical function in the design of electric machinery. While the core design discipline is electro-magnetics, other classic mechanical engineering expertise is required to create state of the art electric machines. Various components of electric machines present the thermal design engineer with obvious applications of classic, well-known solutions. These would include simultaneous thermal and hydro-dynamically developing flow when considering the long, narrow cooling ducts placed between stator laminations. However, the cooling of end windings of a formed, lap-wound electric machine is more challenging. This area features insulated copper coils that extend out of the stator or rotor and return to another section of the machine to complete the loop of a single coil. Effective thermal and flow analysis of this basket-like shape does not easily lend itself to well-known solutions. The present study explores the current literature of this type of machine end-windings as related to thermal and flow solutions. Simple correlations are proposed to aid machine designers that would accelerate the design process. These correlations can be used in thermal and fluid network programs to quickly predict flows and temperatures in a machine. Recent work to characterize heat transfer performance from the pressure drop in heat exchangers using the Generalized Leveque Equation can be of particular value for this effort. Finally, simple Computational Fluid Dynamics (CFD) analysis is presented for a simple geometry similar to a single, isolated stator bar.
Diffusive-Ballistic Heat Transport in Thin Films Using Energy Conserving Dissipative Particle Dynamics
Authors: Yamada Toru , Hamian Sina , Park Keunhan , Asako Yutaka , Faghri Mohammad
Published: October 2013

Diffusive-ballistic heat transport in thin films was simulated using energy conserving dissipative particle dynamics (DPDe). The solution domain was considered to be two-dimensional and DPD particles were distributed in the solution domain uniformly under constant temperature boundary conditions at the top and bottom walls and periodic boundary at the side walls. The effects of phonon mean free path was incorporated by its relation to the cutoff radius of energy interaction. This cutoff radius was obtained based on Knudsen number using the existing phonon-boundary scattering models. The simulations for 0.1 < Kn < 10 were conducted with the different modifications of the cutoff radius. The results were presented in form of temperature profile across the thin film and were compared with the semi-analytical solution of the equation of phonon radiative transport (EPRT). The discrepancy of the simulations without the phonon mean free path modification was less than 15% with EPRT. Good agreement with EPRT to within 5% was obtained when the phonon-boundary scattering effects were included.