bluuebunny/crossref_metadata_2025 huggingface dataset:
Parametric Analysis and Optimization of Inlet Inflection Angle in Torque Converters
Authors: Liu Cheng , Untaroiu Alexandrina , Wood Houston G. , Yan Qingdong , Wei Wei
Published: April 2014

Torque converters are widely used in all means of transportations, such as cars, buses, trucks, and the list can go on. Since power is transmitted via fluid, the blade geometry which forms the flow passages is crucial to torque converter performance. The inlet deflection angle is an important blade design parameter with respect to both performance and manufacturability of torque converters. In the conventional design procedure, inlet deflection angle is often given by the designer’s experience or is selected based on experimental data if available. This study presents a method of optimizing the inlet deflection angle for torque converters and provides a series of non-inferior solutions for the decision maker to select from. The advantages of the method proposed consist of improved design quality and significantly shorter design cycle. A combination of computational analysis and global optimization algorithm was used in this study. A torque converter base model was evaluated using computational fluid dynamics for predicting its performance. The proper grid density and turbulence model were selected through correlation to the experimental data available. The following tasks were automated and integrated to form a parameterized design loop: 1) torque converter flow field CAD modeling, 2) meshing, and 3) CFD simulations and results post-processing. Selecting peak efficiency, stall torque ratio and stall pump capacity factor as objective functions, a multi-objective genetic algorithm was included in the design loop to optimize the torque converter performance.

The CFD results proved to be in good agreement with the experimental data over the range of operating conditions considered in this study. The influence of inlet deflection angle on the performance of torque converter was determined through a parametric analysis and a series of Pareto-optimal solutions were determined by the optimization procedure, which proved to improve the performance of the base model torque converter.
Dynamic Stability and Natural Frequency of Composite Corrugated Bellow Expansion Joint
Authors: Nakkanti SujanaRao , Madabhushi Radhakrishna , Adusumilli MuraliKrishnaPrasad
Published: April 2014

The paper deals with torsional stiffness and natural frequency of composite corrugated bellows type of expansion joint. In this paper simplified formulae are developed considering thin walled pipe model. Integration method is used to determine the natural frequency of bellows. The EJMA {1} method of calculating the torsional frequency is modified using two different equivalent radii. The results obtained by the modified method are compared with the finite element method and found to be in good agreement.
Modeling and Stability Analysis of Truncated High Density Lipoprotein (HDL) System Using Martini Coarse Grain Technique
Authors: Damirchi Behzad , Rouhollahi Amir , Sohrabi Salman , Nemati Mehr Seyyed Mahdi
Published: April 2014

Lipoproteins are biochemical compounds containing both proteins and lipids. These particles carry chemicals like cholesterol and triglycerides that are not soluble in aqueous solutions. This paper presents modeling of lipoprotein system using coarse grain molecular dynamics technique and stability analysis of this system in a water solution like blood. A high density lipoprotein (HDL) that consists of two annular monomers is modeled. Also there are lipid bilayers located in center of the rings, so the whole HDL and lipid bilayers are called lipoprotein system. First, all atom model is provided and then coarse-grain model is obtained using MARTINI technique. Modeling of the system in all atom and coarse-grain is performed by VMD and simulation is executed by NAMD. System is simulated for 400ns with time step of 20fs in NPT ensemble. System temperature assumed similar to normal human body temperature. Finally the structure shape and stability of system were considered and results were analyzed.
The Integration of Quality Function Deployment and Computer Aided Design in Seat Comfort Design and Analyses
Authors: Amer Saed , Onyebueke Landon
Published: April 2014

The concerns of comfortable seat grew more momentous as this era brought new technologies leading to nonstop flights and more dependence on computers; hence, individuals spend more time seated to perform everyday activities. Uncomfortable prolonged sitting may reduce the quality of such activities and may yield health implications. Seat comfort evaluations are conventionally done post-production i.e. a fully produced seat is usually required in order to evaluate its level of comfort. Also, the inputs from the customer which could have significant impression on the comfort level of the seat are usually not considered during the design stages. This study proposes a solution with a system that performs seat comfort design and evaluation by integrating a Quality Function Deployment (QFD) tool with Computer Aided Design (CAD) technique. Several laboratory tests were performed to validate the proposed technique and the obtained results verify that the system can be a valid tool that can surrogate the traditional techniques for comfort analyses. The proposed system offers a comprehensive and systematic tool for the design and prediction of seat comfort by integrating the voice of the customer via QFD into CAD. Taking everything into account, the proposed system will diminish the need for physical prototyping, limit the involvement of human subjects and facilitate information sharing.
Investigation of Frictional Effects on Buckling Behavior of Drill String
Authors: Abdo Jamil , Al-Sharji Hamed , Haneef Danish , Alzebdeh Khalid
Published: April 2014

The in-house developed experimental setup that imitates the wellbore being drilled in presence of surrounding drilling fluid is utilized to investigate the buckling phenomena of drill string. The paper also presents experimental investigations on the effect of changing the friction coefficient on the buckling lock-up situations of drill string. Results reveal that axial transferred loads decrease with the increase of friction coefficient. The results, highlights the significance of changing the drilling fluid rheology, mainly the friction factor, to reduce the friction between the wellbore and the tubing, and thus improve axial force transfer which is mainly responsible for initiation of buckling and limited reach of drilling operation. Drilling fluid with lower friction factor significantly reduces the friction between the tubing and the wellbore. The tube takes the same shape with the change of COF at the same load.
Integrating Safety Into Academic Culture
Authors: Kuespert Daniel R. , Leon Nathaniel J.
Published: April 2014

Integrating safety with business operations is a problem which challenges all industries, and it can pose unique concerns in academia, as pointed out by a variety of recent reviews of academic safety. Academics must incorporate safety concepts into the engineering and science curricula without significantly adding to the students’ course loads, and they must attempt to make safety education a facilitator of teaching and research activities instead of, as is often perceived, an impediment. Several factors drive this effort in addition to the risk of injury or illness, including litigation, societal expectations for “safe products,” and potential for loss of research funding or tuition if safety is not included in the institution’s core values. This paper will explore challenges faced and initial successes achieved by one university in enhancing its safety culture and reducing overall risk.
Modeling and Control Design for a Wheeled Mobile Platform
Authors: Jung Byungchan , Flashner Henryk , McNitt-Gray Jill
Published: April 2014

A model of a wheeled platform that includes slipping is formulated. Slipping is modeled by adopting the LuGre friction model. This is a dynamic friction model that can reproduce realistic friction phenomena not present in static friction models. Using the backstepping approach, tracking controllers for non-slipping and slipping cases are developed and compared via simulation. The proposed control law is designed to be robust with respect to the change in system parameters such as the platform’s mass and moment inertia. Simulation results show good performance for point stabilization in specific destination postures, as well as for tracking.
An Experimental Study on the Mode I Fracture Behavior of Hexagonal Honeycombs
Authors: Uddin Md Salah , Ju Jaehyung , D’Souza Nandika
Published: April 2014

Cellular materials have a high strength-to-weight ratio, which is good for lightweight structural applications. In order to accelerate the commercial use of cellular materials in the structural applications, a well understanding of fracture behavior of cellular materials is required in terms of structural integrity. The objective of the study is to develop a predictive model on fracture behavior of orthotropic cellular polymers, prepared from an additive manufacturing method, under the mode-I macroscopic loading. The constituent material’s fracture properties are obtained from the three-point bending test of samples with a notched crack. Using the base material’s properties, a model on fracture toughness of hexagonal honeycombs with a varying cell angle is developed using a linear elastic fracture mechanics (LEFM) model of a cell wall material. Numerical and experimental tests will follow to validate the model.
Solar Energy in the Housing: Case — Mexicali, Baja California, Mexico
Authors: Campbell Ramírez Héctor Enrique , Delgado Rendón René , Lambert Arista Alejandro A. , Samaniego Ramos Margarita Gil
Published: April 2014

A study was designed and implemented to simulate and validate experimentally the thermal performance and energy of two houses equipped for efficient use of energy in Mexicali, Baja California, Mexico. The objectives were the simulation and the assessment of energetic, economic, social and environmental impacts of the use of high efficiency air conditioning, high efficiency refrigerators, Solar Water Heater (SWH) and photovoltaic (PV) modules. The simulations carried out were validated by field measurements during years 2011 and 2012. For PV systems, we estimated generation of 1837 kWh/yr. and in the annual monitoring values were obtained 1855 kWh/yr. For SWH, the investment is recovered within a reasonable time (6 years) by saving conventional energy. Electricity consumption per unit area of building for winter and summer was 0.23 and 0.46 kWh/ft2, respectively. The field data of average power for the AC is consistent with the SEER 13 being of 1.0 kW, and for the refrigerator, average power was 128 W. For the 2-story house (1033 sq. ft.), simulation predicted an annual consumption of 4559 kWh and measured value was 4197, PV system contributed 55% of consumption. In regard to the estimated electric bill was for $233 USD, and the reported value was $207 USD. The PV cells contributed with 60%, and the electric utility invoice was $78 USD. In these prototype homes is significantly diminishing electricity consumption in contrast to habitual housing. When energy efficiency is achieved as a first goal, the contribution of renewable energy becomes significant. However, for the PV systems, there is much to do, as combining lower investment with funding polices, because, when energy use is reduced, by energy efficiency and saving programs, customers have a subsidized electricity rate. We strongly recommend focus the subsidy for the users and not to the electricity rates. The way to use energy and habits of user, impacts significantly saving actions and energy efficient and the development of renewable energy. It is not easy to compare houses with different family behaviors. We recommend carry out energy education programs, to induce the market for energy saving and renewable. The monitoring allowed a better assessment of current performance of photovoltaic modulus and inverters, and the effects of temperature; radiation changes due to shade and clouds; dust on surfaces, and of the quality and stability of the supply lines (voltage variations), over their behavior and efficiency. Finally, field experiences will help to develop non-invasive systems, using telemetry of data and control commands, which must be combined with the design of house facilities in such a way forward to smart systems.
Development of Novel ‘Duplex NiCr-Coated’ Nanostructured HVOF WC-17Ni(80/20)Cr Coatings for Severe Wear Applications
Authors: Saha Gobinda C. , ben Mahmud Tarek A. , Khan Tahir I.
Published: April 2014

Thermally sprayed coatings have long been used to develop engineered surfaces for protection from severe degradation due to abrasive/erosive wear. High Velocity Oxy-Fuel (HVOF) thermal sprayed cermet composite coatings based on WC-Co systems offer better wear resistance and greater application flexibility compared with the traditional surface treatment techniques such as hardfacing. Recently, the development of nanostructured surfaces based on HVOF deposition of nano-grain WC reinforced in a variety of alloy matrix based cermet systems have gained research focus thanks to their initial performance results, including high hardness and wear properties without concomitant loss of ductility or fracture toughness in the sprayed coatings. In this research, the novel design and manufacturing of the ‘duplex Co-coated’ nanostructured WC-17Ni(80/20)Cr cermet powder is developed. The spraying of the feedstock is carried out using a diamond jet DJ2600 HVOF spray gun. In this study the mechanical properties of the novel coating are investigated and compared with the industry-standard microstructured WC-10Ni-5Cr coating.
Isobaric, Isochoric and Supercritical Thermal Energy Storage in R134a
Authors: Furst Benjamin I. , Lavine Adrienne S. , Baghaei Lakeh Reza , Wirz Richard E.
Published: April 2014

The effective thermal energy density of R134a subjected to an isobaric or isochoric process is determined and evaluated in the two-phase and supercritical regimes. The results are qualitatively extended to other fluids via the principle of corresponding states. It is shown that substantial increases in volumetric energy density can be realized in the critical region for isobaric processes. Also, for isobaric processes which utilize the full enthalpy of vaporization at a given pressure, there exists a pressure at which the volumetric energy density is a maximum. For isochoric processes (supercritical and two-phase), it is found that there is no appreciable increase in volumetric energy density over sensible liquid heat storage; the effective specific heat can be enhanced in the two-phase, isochoric regime, but only with a significant reduction in volumetric energy density.
Geothermal-Driven Ejector Refrigeration System
Authors: Redo Mark Anthony B. , Berana Menandro S.
Published: April 2014

A mathematical model of a heat-driven ejector refrigeration system that uses geothermal energy as the heat source was established. Philippine low-enthalpy geothermal resources were investigated and became the bases in computing for the heat at the generator part of the ejector refrigeration system. Analysis and comparison of the performance of the cycle considering working fluids like ammonia (R717) and R134a as the refrigerants were conducted. The properties of those fluids were based on an available thermodynamic database of various refrigerants. The governing principles and conservation equations for energy, mass and momentum were successively applied to control volume of ejector components. The properties for both fluid and flow were solved iteratively for isentropic and irreversible processes wherein entropy generation and frictional losses were accounted for. This included simulation of flows in two-phase region. Input parameters were set like the generating temperature and condensing temperature. The range of 60 to 100 °C available geothermal fluid temperature could produce 50 to 90°C of generating temperature for the fluid refrigerant. This range of generating temperature yielded an evaporating temperature of 8 to 25 °C at a fixed condensing temperature of 40 °C. After numerical analyses, the determined coefficient of performance was at the range of 0.21 to 0.39, while nozzle and ejector efficiencies were from 94% to 99%. The geometric profiles of the ejector were also projected along with the varying generating temperature for both fluids. From the calculation, ammonia offers higher performance and efficiencies and lower evaporating temperatures suitable for larger cooling needs.
Autoignition Variation of Biodiesel Surrogates: Influence of Saturation
Authors: Wang Weijing , Gowdagiri Sandeep , Oehlschlaeger Matthew A.
Published: April 2014

The autoignition of three biodiesel surrogates (methyl decanoate, methyl 9-decenoate, and a mixture of methyl 5-decenoate and methyl 6-decenoate), representative of the organic structures found in fatty-acid methyl ester (FAME) biodiesels, has been studied using the reflected shock technique. Measurements of ignition delay times were carried out at 20 atm for temperatures ranging from 700 to 1300 K, spanning all three regimes of reactivity of interest to diesel engines. At high temperatures (> 900 K) the three surrogate components have indistinguishable ignition delay. While in the negative-temperature-coefficient (NTC) and low-temperature regimes (< 900 K) the deviation in ignition delay based on the location of the double bond with the methyl decenoate carbon chain is around a factor of two. The results show that location of double bonds within FAME biodiesel components will have an important role in governing the NTC and low-temperature reactivity for FAME biodiesels but is unimportant at high-temperatures, of significance for the development of biodiesel surrogates and modeling strategies for diesel engine simulations.
Chemical Affinity Tensor and Stress-Assist Chemical Reactions Front Propagation in Solids
Authors: Freidin Alexander B.
Published: April 2014

We consider a stress-assist chemical reaction front propagation in a deformable solid undergoing a localized chemical reaction between solid and gas constituents. The reaction is sustained by the diffusion of the gas constituent through the transformed solid material. We introduce a chemical transformations strain tensor that relates two reference configurations of solid constituents. Then mass, momentum and energy balances are written down for the open system considered and the expression of the entropy production due to the reaction front propagation in a solid with arbitrary constitutive equations is derived. As a result, the expression of the chemical affinity tensor is obtained. Kinetic equation for the chemical reactions front propagation is formulated in a form of the dependence of the front velocity on normal components of the chemical affinity tensor. The locking effect — blocking the reaction by stresses is demonstrated. Finally the kinetic equation for the bulk chemical reaction is derived in a form of the dependence of the reaction rate on the first invariant of the chemical affinity tensor.
Characterizing the Accuracy of FDM Rapid Prototyping Machines for Machine Design Applications
Authors: Etesami Faryar , Griffin Tim
Published: April 2014

This paper presents experiment-based formulas that predict the geometric accuracy of Fused Deposition Modeling (FDM) rapid prototyping (RP) machines in a form suitable for fit and function applications. The proposed method establishes the accuracy of several base-level geometry characteristics such as line straightness and circularity through direct measurements. Statistical analyses are used to establish reliable prediction formulas for the base-level geometry characteristics. The base-level accuracy measures are then used to develop models for higher-level geometric accuracies such as orientation, position, or profile accuracy. The objective of the methods proposed in this paper is to help FDM manufacturers develop reliable measures of accuracy for their machines in a form that is directly applicable to mechanical design applications. The proposed procedure is simple enough that companies that own and use FDM machines can quickly develop in-house accuracy measures that are specifically relevant to their machines. This study does not make any claims regarding the absolute accuracy of FDM machines in general. Rather, the study suggests a methodology for characterizing the accuracy of existing machines or production models in a manner useful to fit and function design work. The methodology applies to other rapid prototyping technologies as well.
Transient Wave Propagation in a Materially Nonlinear Beam
Authors: Liu Yu , Dick Andrew J.
Published: April 2014

In this paper, the transient wave propagation in a materially nonlinear beam is studied. Based on previous research, the geometric nonlinearity can be neglected in an intermediate strain regime. An equation of motion for a cubic material nonlinearity is derived. The alternating frequency-time finite element method (AFT-FEM) is applied to the beam model. Numerical simulations are conducted. Significant nonlinear behavior is observed in the response. Depending on the local nonlinear property of the material in the intermediate strain regime, the amplitude of the wave response can be influenced. The nonlinear properties can also influence the dispersive characteristics of the intrinsically dispersive beam model.
Multiscale Modeling of Nano-Reinforced Structural Adhesive Bonds
Authors: Wernik Jacob M. , Meguid Shaker A.
Published: April 2014

In this work, the mechanical properties of carbon nanotube reinforced structural adhesive bonds are investigated both theoretically and experimentally. The theoretical investigations employ a novel multiscale modeling technique that integrates governing atomistic constitutive laws in a continuum framework. This technique takes into account the discrete nature of the atomic interactions at the nanometer length scale and the interfacial characteristics of the nanotube and the surrounding polymer matrix. Appropriate formulations are developed to allow for the atomistic-based continuum modelling of nano-reinforced structural adhesive bonds on the basis of a nanoscale representative volume element that accounts for the nonlinear behaviour of its constituents; namely, the reinforcing carbon nanotube, the surrounding adhesive and their interface. This model is used to evaluate the constitutive response of carbon nanotubes with varied chiral indices. The newly developed representative volume element is then used with analytical micromechanical modeling techniques to investigate the homogeneous and dispersion of the reinforcing element into the adhesive considered upon the linear elastic properties.
Computation of Forward-Time Finite-Time Lyapunov Exponents Using Discontinuous-Galerkin Spectral Element Methods
Authors: Nelson Daniel A. , Jacobs Gustaaf B.
Published: April 2014

We present an algorithm for computing forward-time finite-time Lyapunov exponents (FTLEs) using discontinuous-Galerkin (DG) operators. Passive fluid tracers are initialized at Gauss-Lobatto quadrature nodes and advected concurrently with direct numerical simulation (DNS) using DG spectral element methods. The flow map is approximated by a high-order polynomial and the deformation gradient tensor is then determined by the spectral derivative. Since DG operators are used to compute the deformation gradient, the algorithm is high-order accurate and is consistent with the DG methods used to compute the fluid solution. The method is validated with a benchmark of a periodic gyre, a vortex advected in uniform flow and the flow around a square cylinder. An exact equation for the FTLE of the advected vortex is derived.
Methodology for Haptic Modeling of Trocar Insertion Procedure
Authors: Seo Yong Won , Chowriappa Ashirwad , Abraham Anand , Guru Khurshid , Kesavadas Thenkurussi
Published: April 2014

Trocar insertion is the first step in laparoscopic surgery procedures. It is a difficult procedure to learn and practice because it is carried out almost entirely without any visual feedback of the organs underlying the tissues being punctured. A majority of injuries are attributed to excessive use of force by surgeons. So there is a need for a haptic based computer simulator to train and improve the trocar insertion skills. In this paper, a new methodology for the modeling of trocar insertion is proposed. First, trocar insertion data (force/torque, displacement, etc.) are collected from animal models. Based on this data, a material model is computed using a hyper-elastic finite element computation (FEM). Using the FEM model, tissue deformation of the abdominal wall is calculated off-line for various conditions of tissue puncture. Deformation data are used to train a neural network which is, in turn, used to compute a real time virtual trocar insertion simulation. Force feedback is also modeled based on clinical data and is integrated into the simulator. This novel method allows for precise trocar insertion simulation based on prior FEM offline computation. The proposed system was implemented in a laboratory environment.
Numerical Analysis of Laminar Natural Convection in Rectangular Enclosures of Different Aspect Ratios With and Without Aerosol Nanofluid
Authors: Rahman Mosfequr , Hudson Andrew , Molina Gustavo , Soloiu Valentin
Published: April 2014

Natural convection heat transfer in rectangular enclosures is important in many real-world engineering applications. Included in these applications are the energy efficient design of buildings, operation and safety of nuclear reactors, solar collector design, passive energy storage, heat transfer across multi-pane windows, thermo-electric refrigeration and heating devices, and the design-for-mitigation of optical distortion in large-scale laser systems, environmental engineering and electronic packaging. A common industrial application of natural convection is free air cooling without the aid of fans and can happen on small scales such as computer chips to large scale process equipment. In addition to temperature gradient convection strength within the enclosure can vary due to the existence of nanoparticles with the base fluid.

The field of nanofluid research has been expanding in recent years. Most of the research performed for the purpose of heat transfer using nanofluids has been conducted on liquid based nanofluids, leaving the aerosol-based nanofluid research lagging. There is also a deficit in the research previously performed to develop a computer model of heat transfer enhancement using nanofluid. The transport of solid particles and liquid droplets in a fluid has long been a subject of great interest. Understanding, measuring, and quantifying the deposition of aerosol on walls is important in various sectors of science and technology. Some examples are the deposition of drugs and harmful substances in the nasal and respiratory tracts in medical science and engineering; deposition of particles and droplets in gas and steam turbines in power plant engineering; the atmospheric dispersal of pollutants and the determination of indoor air quality in environmental science; the transport and sedimentation of various substances in rivers in civil engineering; fouling of process and heat transfer equipments in process industries; and the transport of chemical aerosols in chemical process engineering. In this research work the case of pure air was first solved for 6 different aspect ratios, then the nanofluid was introduced and the resulting heat transfer was observed. The aerosol nanofluid used was composed of air with copper nanoparticles suspended in an enclosure. This procedure was repeated for multiple aspect ratios. This research also develops a functional computer model for heat transfer enhancement using nanofluid.
Integration of Fiber Optic Sensors in Measuring Machines
Authors: Davanlou Ashkan
Published: April 2014

The production metrology of today is still dominated by tactile probing systems. However some special metrological tasks cannot be fulfilled by this technique, one example is in the high precision manufacturing of surfaces and structures, which become ultra-miniaturized, complex and fragile. The inspection of small boreholes and cavities is also an example with very tight tolerances which demands non-contact miniaturized sensors. Particularly the measurement of the shape of spray holes in modern fuel injection nozzles for diesel engines fits this statement, as its shape represents the key factor for maximal motor efficiency, as well as minimal pollutant emissions. Any deviation from its design shape significantly affects spray breakup and can lead to unequal distribution of flow and pressure changes. These holes can have diameter of 150 microns, with a tendency to even smaller diameters in future systems.

Within this work the integration of a fiber optic sensor for distance measurements in measuring machines, specifically for borehole inspection, is described. The used device is a form-tester (Mahr GmbH, MMQ-400) with 3 degrees of freedom. The motion of the machine axis will be controlled with help of image processing operation which are based on pictures taken from the specimen’s top surface. For this mean a micro camera will be mounted on the form-tester. By applying in-house developed MATLAB codes, the exact position of the boreholes and that of the fiber optic probe is obtained, so that an automated positioning and measurement (e.g. round-out and roundness tests) could be performed. This process enhances both the precision due to an optimized sensor positioning and speed of the measurement rather than manual execution. Different positioning scenarios will be discussed and compared in this paper, to prove the capability of the proposed system as well as its adaptivity.
Numerical Modeling of Fluid Flow and Thermal Behavior in Geothermal Heat Exchangers
Authors: Thompson Willis H. , Ekkad Srinath V. , Olgun C. Guney , Wheeler Joseph
Published: April 2014

Geothermal heat exchangers are highly dependent on the local heat exchange capacity and ground thermal properties. The ability to simulate performance and testing of geothermal heat exchangers is limited. Therefore thermal conductivity tests are usually required for correct sizing of geothermal heat exchange systems. To better understand these tests in relation to energy piles, a 3D finite element model was created using the COMSOL software to simulate the thermal conductivity test of a 12inch (30cm) energy pile. The finite element simulation was created and validated using experimental data to expand the comparisons made between geothermal boreholes and energy piles. In this study, the numerical finite element model has been recreated using the commercial computational fluid dynamics (CFD) software ANSYS which incorporates fluid flow effects. Confirming that the CFD model can accurately model the thermal conductivity test provides an additional tool that will be valuable in modeling geothermal heat exchangers. Results show that parametric variations in terms of fluid flow rate and fluid selection are easier to evaluate using the CFD model compared to the finite element model. Results are also compared with discrete thermal conductivity measurements obtained from real geothermal heat exchangers.
A Numerical Study for Contained Cold Aisle Data Center Using CRAC and Server Calibrated Fan Curves
Authors: Alkharabsheh Sami A. , Sammakia Bahgat G. , Shrivastava Saurabh , Schmidt Roger
Published: April 2014

In the present work, we demonstrate the effect of Cold Aisle Containment Systems (CACS) on the airflow and temperature distribution inside a representative data center. Computational Fluid Dynamics (CFD) is used to conduct this analysis. This study includes calibrated fan curves in the Computer Room Air Conditioner (CRAC) and the servers in order to capture the impact of pressure changes on the flow field. The system characteristics curve for the open (uncontained) system and contained system including the leakage effect is established. Since the IT-equipment has a crucial effect on the performance of contained systems, the individual and combined effect of fully enclosing the cold aisle and IT-equipment are investigated. Partially contained systems including doors only and ceilings only configurations are also considered in this study. Steady state and dynamic scenarios are simulated to characterize different containment systems.

It is found that the pressure inside the fully contained system is determined by the IT-equipment as well as the geometrical obstructions of fully containing the cold aisle. Increasing the pressure due to enclosing the cold aisle is reduced by introducing IT-equipment, load banks in this case, which leads to a reduction of the total static pressure and an increase of the flow rate. It is also found that the fully contained system presents the best configurations in achieving low and uniform temperature distribution; however, partially contained systems can be a good solution if a certain cold air provision is maintained during operation. The dynamic analysis shows a significant increase in the safe time at full CRAC failure scenario compared with uncontained system due to utilizing the trapped cold air inside the plenum by the load banks fans.
Sustainable Reverse Engineering Methodology Assisting 3D Modeling of Footwear Safety Metallic Components
Authors: Silva Joel V. , Costa Sérgio L. , Puga Hélder , Peixinho Nuno , Mendonça João P.
Published: April 2014

One main objective of the technique of reverse engineering is focused on development of new products based on the improvement of existing products. The present work aims to demonstrate a sustainable methodology exploring the capabilities of reverse engineering, applied to produce brand new geometric solutions for safety metallic components incorporated in footwear. The data acquisition is done using different techniques, contact methods (CMM – Measuring Coordinate Machine) and non-contact methods (Laser Scanning). Those measuring techniques for data acquisition are the key entry for the 3D shape recovery, boosting the development of new components based on the improvement of existing products. Despite these techniques being widely explored in multiple engineering sectors, author’s contribute was focused on the proposal and validation of a sustainable methodology based on an algorithm in MATLAB that performs the surface generation under user control. Such methodology has been tested through a real model of a toecap component used in safety footwear.
Re-Examination of NHTSA’s Research Moving Deformable Barrier Front Oblique Impacts With Vehicle to Vehicle Crashes Using FE Models
Authors: Brar Bavneet S. , Tangirala Ravi
Published: April 2014

The objective of this study is to investigate how the target vehicle’s structural response to NHTSA’s Research Moving Deformable Barrier (RMDB), during oblique impact conditions, compares with actual vehicle to vehicle impacts. It tabulates vehicle kinematics, deformation mode and structural intrusions for both the simulated field accident situations, with a SUV and a small car bullet vehicles, onto a small car target vehicle. These parameters are then compared with those resulting from the RMDB impact simulations. The differences are highlighted and quantified. The effects of the bullet vehicles variation in impact speed were also investigated.

The paper details sensitivity of the RMDB’s Principle Direction of Force by varying the impact overlap percentage. Lastly, further modifications to the RMDB have been suggested to improve its vehicle to vehicle relevance. The FE models used in this research were a full vehicle, restraints and occupant integrated small car model along with a midsized SUV simulation model.
Repurposing Waste Steam and Hot Water to Accelerate Plant Growth in Heated Green Roofs
Authors: Dell Robert , Unnthorsson Runar , Wei C. S. , Foley William
Published: April 2014

Municipal steam district heating services such as New York City’s Consolidated Edison’s have no recirculation system. The waste heat, usually in the form of steam condensate and hot water, is mixed with and cooled by municipal potable water. Since 2006, The Center for Innovation and Applied Technology and The Laboratory for Energy Reclamation and Innovation at the Cooper Union have been developing a system to use this thermal pollution to heat the growth medium of green roofs. The authors have also constructed three geothermal heated gardens systems in Iceland. American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) specifications for heated sidewalks were referenced in all locations.

The heated green roofs have the potential to save more than 2,000,000 cubic meters of potable water if applied to 40% of Consolidated Edison’s steam customers. Plant growth is often accelerated by 20% or more in all locations.
CFD Loading Assessments on a Liquid Quenched Propane System
Authors: Kinzel Michael P. , Pal Sanjeeb , Diwakar Philip , Messersmith David , Ganjam Sanjay , Desai Prakash , Kennedy Christopher , Prakash Ajay , Berkoe Jonathan , Pelter Leonard Joel , Knight Kelly J.
Published: April 2014

In designing propane quenching systems, a number of concerns arise with the specific fluids properties, thermal, and structural behavior of the system. In this work, the fluid-based loading on a quenched piping system is examined using computational fluid dynamics (CFD). Fluids loading is assessed during an event when a propane line is liquid quenched prior to a recycle valve opening event. During the event, hot vaporous propane is quickly exhausted into the quenched pipe. The CFD studies suggest that the loading in such an event is much larger than a similar event where the line is not quenched. Several aspects of the quench are shown to increase the loads with respect to the non-quench line, and appear to be associated with two mechanisms. The first load amplifying mechanism is the reduction of sound speed in a liquid/vapor mixture. This effect impacts the axial load in the pipe, and increases it multiple orders of magnitude as compared to a pure vapor flow. The second load increasing mechanism observed was due to slug formation. It was found that when considering quench stream droplets, stratification layers are likely to develop eventually within long pipes as the velocity from the nozzles is dissipated in the large line. In the pipe investigated, the hot, high-speed vapor blows the stratified liquid into a slug. When the slug makes turns through elbows, the pipe axial load increased even more. Simultaneously, a similar scale, perpendicular load was also observed. The overall results suggest that these loading events are not small and should be considered in the structural design and layout of a quenching system. The series of results also indicates that CFD provides a valuable tool for assessing complex two phase fluid issues, in particular for the loading on a pipe.
Formula Electric: Design and Integration
Authors: Villa Dominic , Allison Mark , Claggett Kevin , Hopson Stuart , Hight Timothy , Beitelmal Monem
Published: April 2014

A new electric power train design to power an open-wheel, single seat electric race car to compete in the 2014 SAE Formula Electric competition is presented. This research project is part of the clean technology initiative for sustainable energy sources for automotive application proposed by the Santa Clara University Formula Electric (SCUFE) team. In this paper, a new battery pack design and integration is evaluated. This includes analysis of battery cell connectivity, cell enclosure, safety system, and battery control system. The cell connectivity proposed will maximize electrical conduction through surface area contact of the cell tabs while allowing for quick removal of individual cells in the case of cell failure. The structure of the pack enclosure will consist of polycarbonate panels. The connection panels will be mounted between the wall enclosure lid and wall in order to prevent the pack from being opened when the contactors are engaged, preventing the risk of exposure to high voltage. The proposed design allows the pack to be completely removed from the vehicle for easier disassembly and transportation. The exterior connections will consist of one large plug for the power cables as well as a smaller plug assembly for the battery management system (BMS) and other necessary sensors and connections. Cell voltage states will be monitored through the BMS. In addition, maximum voltage capacity and cell storage capacity will be analyzed and discussed. Recommendations on future designs will also be presented in light of preliminary results on the efficiency versus performance.
Undergraduate Research on Trailer-Truck Aerodynamic Drag
Authors: Atiqullah Mir , Sanchez Rigoverto , Hamler Benjamin
Published: April 2014

The transportation industry is heavily dependent on ‘big rigs’ or semitrailers. Since its introduction during 1920s semitrailers have revolutionized the industry. However their geometrical designs have not evolved much to make them aerodynamically more streamlined, thus more fuel efficient. While over 5.6 million such commercial trailer trucks are registered in the country and with increasing diesel fuel prices, it is more important than ever to study their aerodynamics, redesign for reducing aerodynamic drag and help make these ‘big rigs’ more fuel efficient. Aerodynamic drag is the force that acts on a solid object moving in air due to difference in dynamic pressure developed around that object. Skin friction also causes resistance force which is small compared to pressure induced drag. Higher drag resistance, just like road and tire resistance, causes loss of energy and thereby lowers fuel mileage. Drag resistance is caused by both surface friction as well as air pressure difference around a moving object/vehicle. An ideal remedy is of course to completely redesign the shape and size of these semitrailers to conform to those with known low drag. Another intermediate approach would be to retrofit the existing semitrailers with devices that change the overall shape towards more aerodynamic ones. During the recent past a wide range of such add on devices have been introduced. Current research was directed in two fronts: CAD and Drag simulation as well as experimental drag testing. First a base CAD model and then various modifications were developed using an industry standard CAD package. These models were then imported into Computational Fluid Dynamics (CFD) software. These followed by modeling add-on devices to reduce drag. The simulations were repeated with various combinations of these add-on drag reducers. The areas targeted for drag reduction study included gap between tractor and trailer, lower sides of the trailer between front and rear wheel sets, and rear of the trailer. The results showed varying effectiveness of these add-on devices, individually and in combination. Scale models of the trailer truck were built using wood as well as Rapid Prototyping (RP) directly from CAD using polymer. These models were then tested in the wind tunnel at speeds between 35 and 75 miles per hour. The data and the trends in Cd values compared well with the simulated values. The overall CFD and scale model studies provided a comprehensive knowledge and understanding of the drag in semi-trailers and factors that affect it. Future studies may expand the varieties and locations of these devices as well as complete redesigns of the trailer-trucks.
An Experimental Study of Turbulent Non-Newtonian Fluid Flow in Concentric Annuli Using Particle Image Velocimetry Technique
Authors: Bizhani Majid , Rodriguez Corredor Fabio Ernesto , Kuru Ergun
Published: April 2014

Turbulent flow of a Non-Newtonian polymer fluid through concentric annuli was studied using 9 m long horizontal flow loop (inner to outer pipe radius ratio = 0.4) and Particle Image Velocimetry (PIV) technique.

A high molecular weight, anionic, water soluble, acrylamide-based copolymer was used as a viscosifier. The aqueous polymer solution exhibited power law rheology with strong shear thinning behavior.

Experiments with aqueous polymer solutions have been conducted at the same bulk velocity as water experiments. Mean bulk velocity values changed from 0.827 to 1.164 m/s, corresponding to solvent (water) Reynolds number from 46000 to 68000.

Mean axial velocity and Reynolds stress distribution in the near wall region (considering both inner and outer walls) and in the whole annular gap were determined. Axial mean velocity profile was found to be following the universal wall law close to the wall, but it deviated from logarithmic law with an increased slope in the logarithmic zone.

Radial locations of the maximum velocity values were also determined and compared to that of water flow. For the range of Reynolds numbers studied, location of maximum velocity was found to be dependent on Reynolds number. As Reynolds number increased, location of maximum velocity moved closer to inner wall.

Reynolds and laminar stresses were calculated. Reynolds stresses for polymer fluid flow decreased with increasing polymer concentration and were found to be always smaller than that of water. Laminar stresses, on the other hand, were found to be always higher at higher polymer concentration, reflecting the effect of the fluid viscosity.
Implementation and Testing of Adaptive Augmentation Techniques on a 2-DOF Helicopter
Authors: Nuthi Pavan , Subbarao Kamesh
Published: April 2014

This paper presents the design procedure and experimental results of a high performance adaptive augmentation technique applied to a controller derived based on linear quadratic methods. The Quanser 2-DOF helicopter was chosen as the experimental platform on which these controllers were implemented. The paper studies the implementation of each of these controllers stand-alone as well as in the augmented scheme, and discusses its performance and robustness for cases with parametric uncertainties, and unmodeled dynamics. An attempt is made to combine linear quadratic tracker’s reliability with the adaptive augmentation’s robustness towards modeling uncertainties. It is found that appropriate tuning of parameters in the adaptive framework is key to its performance and thus the process of choosing the parameters is elaborated along with guidelines for choosing a reference model. Tuning considerations for controller implementation on the experimental setup as compared to the same on the numerical model are also addressed. The experiments performed on this nonlinear MIMO system serve as a suitable research test and evaluation basis for robotics and flight control applications.
An Advanced Frequency-Domain Code for BWR Stability Analysis and Design
Authors: Askari Behrooz , Yadigaroglu George
Published: April 2014

Density Wave Oscillations in BWRs are coupled with the reactor kinetics. A new analytical, frequency-domain tool that uses the best available models and methods for modeling BWRs and analyzing their stability is described. The steady state of the core is obtained first in 3D with two-group diffusion equations and spatial expansion of the neutron fluxes in Legendre polynomials. The time-dependent neutronics equations are written in terms of flux harmonics (nodal-modal equations) for the study of “out-of-phase” instabilities. Considering separately all fuel assemblies divided into a number of axial segments, the thermal-hydraulic conservation equations are solved (drift-flux, non-equilibrium model). The thermal-hydraulics are iteratively fully coupled to the neutronics. The code takes all necessary information from plant files via an interface. The results of the steady state are used for the calculation of the transfer functions and system transfer matrices using extensively symbolic manipulation software (MATLAB). The resulting very large matrices are manipulated and inverted by special procedures developed within the MATLAB environment to obtain the reactor transfer functions that enable the study of system stability. Applications to BWRs show good agreement with measured stability data.