bluuebunny/crossref_metadata_2025 huggingface dataset:
Thrust Enhancement Through Bubble Injection Into an Expanding-Contracting-Nozzle With a Throat
Authors: Singh Sowmitra , Fourmeau Tiffany , Choi Jin-Keun , Chahine Georges
Published: October 2013

This paper addresses the concept of thrust augmentation through bubble injection into an expanding-contracting nozzle with a throat. The presence of a throat in an expanding-contracting nozzle can result in flow transition from the subsonic regime to the supersonic regime (choked conditions) for a bubbly mixture flow, which may result in a substantial increase in jet thrust. This increase would primarily arise from the fact that the injected gas bubbles expand drastically in the supersonic region of the flow. In the current work, an analytical 1-D model is developed to capture choked bubbly flow in an expanding-contracting nozzle with a throat. The study intends to provide analytical/numerical confirmation to observed phenomena and to serve as a design tool to guide practical experiments aimed at creating and studying choked bubbly flows through nozzles.

Starting from the 1-D mixture continuity and momentum equations along with an equation of state for the bubbly mixture, expressions for mixture velocity and gas volume fraction were derived. Starting with a fixed geometry, an imposed upstream pressure and assuming choked flow in the nozzle, the derived expressions were iteratively solved to obtain the exit pressures and velocities for different injected gas volume fractions. The variation of thrust enhancement with the injected gas volume fraction was also studied. Additionally, the geometric parameters were varied (area of the exit, area of the throat) to understand the influence of the nozzle geometry on the thrust enhancement and on the flow conditions at the inlet. This parametric study provides a performance map that can be used to design a bubble augmented waterjet propulsor that can achieve and exploit supersonic flow. It was found that the optimum geometry for choked flows, unlike the optimum geometry under purely subsonic flows, had a dependence on the injected gas volume fraction. Furthermore, for the same injected gas volume fraction the optimum geometry for choked flows resulted in greater thrust enhancement compared to the optimum geometry for purely subsonic flows.
Analytical Periodic Motions in a Periodically Forced, Damped Duffing Oscillator
Authors: Luo Albert C. J. , Huang Jianzhe
Published: October 2013

The analytical solutions of the period-1 motions for a hardening Duffing oscillator are presented through the generalized harmonic balance method. The conditions of stability and bifurcation of the approximate solutions in the oscillator are discussed. Numerical simulations for period-1 motions for the damped Duffing oscillator are carried out.
Polyhedral Space Curve Meshing Reducer With Multiple Output Shafts
Authors: Chen Yangzhi , Ding Jiang , Yao Chuanghai , Lv Yueling
Published: October 2013

In recent years, a gear named Space Curve Meshing Wheel (SCMW) has been invented based on the meshing theory of space curves instead of classic space surfaces. Well improved in many aspects after its invention, it has been applied within the Space Curve Meshing Reducer (SCMR).

The design method of an invention named polyhedral SCMR is presented in this paper. With single input shaft and multiple output shafts, this SCMR has advantages like compact structure, flexible design and low cost. It is characterized by the application of the SCMW group containing one driving wheel and several driven wheels, whose rotation axes are concurrent at a point and radiate in polyhedral directions. A SCMW group can form a single-stage SCMR, while SCMW groups connected can form a multiple-stage SCMR. In this paper, geometric parameters of the polyhedral SCMR are defined, design formulas are derived, and an example is provided to illustrate the design process.
Grid-Free Vortex Methods for Natural Convection in Two-Dimensional Domains
Authors: Lakkis Issam
Published: October 2013

Vortex methods for simulating natural convection of an ideal gas in unbounded two-dimensional domains are presented. In particular, the redistribution method for diffusion is extended to enable simulation of nonlinear diffusion of an ideal gas in isobaric conditions encountered in unbounded low-Mach number flows. We also address the problem of handling source terms in grid-free vortex methods and propose a fast, accurate, and physically motivated method for solving the associated inverse problems. Examples include generation of baroclinic vorticity in non-reacting buoyancy driven flows, and in addition, generation of internal energy and species in buoyant reacting flows. Accuracy and speed of the proposed algorithms for nonlinear diffusion and vorticity generation are investigated separately. Simulations of natural convection of a “thermal patch” for Grashof number ranging from to 1562.5 to 25000 are presented.
Capitalizing on the Lock-On Phenomenon in the Cooling of Electronic Equipment
Authors: Bourisli Raed I.
Published: October 2013

It is well known that over-heating affects the performance and lifespan of many devices, electronic chips being a prime example. In this work, heat transfer enhancement through topology modification of channels containing heat-dissipating blocks, simulating electronic chips, is investigated numerically using the finite volume method. Specifically, five thin plates are placed close to the downstream upper corners of five blocks in order to force significant fractions of the core flow into the grooves between the blocks. The plates are rotated with a sinusoidal angular velocity, back and forth, so as to affect further mixing of the fluid. The flow was simulated for a number of frequencies of oscillation, at a Reynolds number of 1000 and an amplitude of oscillation of 20 degrees. Results indicate that the periodic movement of the plates provide excellent mixing of the cool, core fluid with the warm fluid near the bottoms of the chips, where the heat is dissipated. Furthermore, the maximum cooling of the blocks, i.e., minimum temperature in the channel, happens when the frequency of oscillation of the plates matches the natural frequency of the structure, the one associated with vortex shedding. It is concluded that the effect of vortex shedding, albeit small on its own in these settings, is quite pronounced when it is in-phase with an external source of oscillation.
Molecular Dynamic Simulation of Thermal Conductivity of Electrically Insulating Thermal Nano-Oil
Authors: Raji K. , Sobhan C. B. , Taha-Tijerina Jaime , Narayanan T. N. , Ajayan P. M.
Published: October 2013

In applications such as coolants in electrical devices, in addition to high heat transfer capabilities, the cooling fluids are required to have low electrical conductivity also. As nanoparticle suspensions (nanofluids) show excellent thermal performance due to enhanced thermal conductivity, it would be advantageous to evolve nanofluid-coolants, which are electrically insulating also, for such applications. A theoretical analysis of one such suspension is performed in the present work, to evaluate the thermal conductivity enhancement due to the presence of nanoparticles in the base fluid. The nanofluid analyzed is a suspension of hexagonal boron nitride (h-BN) in mineral oil, for application as a cooling fluid in electrical transformers. The thermal conductivity of the boron nitride suspension is computed using equilibrium Molecular Dynamics (MD) simulations followed by the application of the Green-Kubo auto correlation function. The Lennard–Jones potentials and simple harmonic oscillation potentials are used as the intermolecular potentials to appropriately describe the various atomic and molecular interactions in the boron nitride suspension. The molecular dynamics simulations are performed using LAMMPS software. The computational results are benchmarked with experimental findings on the thermal conductivity enhancement in the suspension at various temperatures and concentrations of nanoparticles, obtained using a transient measurement technique.
Fatigue Life Improvement of Holed Plates by Interference Fitted Pins
Authors: Croccolo D. , De Agostinis M. , Olmi G.
Published: October 2013

This paper deals with the influence of interference fit coupling on the fatigue strength of holed plates. The effect was investigated both experimentally and numerically. Axial fatigue tests have been carried out on holed specimens made of special microalloyed-steel (896MPa of Ultimate strength and 640MPa of Yield strength) with or without a pin, made of the same material, press fitted into their central hole. Two different conditions have been investigated: the open hole specimens and specimens with 0.6% of nominal specific interference. The experimental stress-life (SN) curves pointed out an increased fatigue strength of the interference fit specimens compared with the open hole ones. The numerical investigation was performed in order to analyse the stress field by applying an elastic plastic 2D simulation with commercial Finite Element software. The stress history and distribution around the interference fitted hole, indicates a significant reduction of the local stress amplitude produced by the external loading (remote stress) since a residual stress field is generated by the pin insertion.
Vibration Power Flow Analysis of a Submerged Constrained Layer Damping Cylindrical Shell
Authors: Wang Yun , Zheng Gangtie
Published: October 2013

The vibration power flow in a submerged infinite constrained layer damping (CLD) cylindrical shell is studied in the present paper using the wave propagation approach. Dynamic equations of the shell are derived with the Hamilton principle in conjunction with the Donnell shell assumptions. Besides, the pressure field in the fluid is described by the Helmholtz equation and the damping characteristics are considered with the complex modulus method. Then, the shell-fluid coupling dynamic equations are obtained by using the coupling between the shell and the fluid. Vibration power flows inputted to the coupled system and transmitted along the shell axial direction are both studied. Results show that input power flow varies with driving frequency and circumferential mode order, and the constrained damping layer will restrict the exciting force inputting power flow into the shell, especially for a thicker viscoelastic layer, a thicker or stiffer constraining layer (CL), and a higher circumferential mode order. Cut-off frequencies do not exist in the CLD cylindrical shell so that the exciting force can input power flow into the shell at any frequency and for any circumferential mode order. The power flow transmitted in the CLD cylindrical shell exhibits an exponential decay form along its axial direction, which indicates that the constrained damping layer has a good damping effect especially at middle or high frequencies.
The Effect of Rate Dependency on the ACL Failure Locus: A Subject Specific Study
Authors: Orsi A. , Vaziri A. , Canavan P. K. , Hashemi H. N.
Published: October 2013

A full or partial tear of the anterior cruciate ligament (ACL) is a common and painful injury that has been estimated to occur approximately 250,000 times annually in the U.S. [1]. Articular cartilage and meniscal injuries are also associated with ACL injuries [2]. ACL injuries can often lead to degenerative osteoarthritis of the articular cartilage [2]. An epidemiology study of athletic injuries by Majewski et al. [3] determined that out of 19,530 sports injuries, 20% were ACL injuries and 8% were medial collateral ligament (MCL) injuries.
Surface Treatment of Polymers for the Fabrication of All-Polymer Microfluidic Devices
Authors: Zhao Jiheng , Sheadel Debra A. , Xue Wei
Published: October 2013

Polymer microfluidics has received considerable attention due to their low cost, remarkable biocompatibility, and high flexibility when compared to glass and silicon devices. However, the fabrication process of all-polymer devices can be complicated. In particular, different types of polymers possess different properties in terms of surface chemistry and hydrophilicity, making device assembly a challenging task. In this paper, we demonstrate the fabrication of an all-polymer device through the investigation of the essential surface treatment methods. A hybrid SU-8-SU-8-polydimethylsiloxane (PDMS) sandwiched structure is used in this research. Both untreated SU-8 and PDMS are hydrophobic and they have different surface chemistry properties, so surface modifications are necessary. Three critical surface treatment steps are used in our process. The first step is to treat the first SU-8 layer with low-power (10 W) oxygen plasma, making its surface hydrophilic. This step enables the uniform coating of the second SU-8 layer. The next surface treatment is on the second SU-8 layer. Both oxygen plasma (40 W) etching and diluted 3-aminopropyltriethoxysilane (APTES, a silane solution) coating are needed. APTES introduces amine (Si-NH2) groups on the surface. The last treatment step is to introduce silanol (Si-OH) groups on PDMS using oxygen plasma. These surface treatment steps are critical in the fabrication process and can determine the quality of the final device.
Modeling of Linear Atmospheric Plasma Reactor
Authors: Chugunov Svyatoslav , Akhatov Iskander
Published: October 2013

Methods of materials deposition and coating based on atmospheric pressure plasma (APP) have gained significant attention these days. Keeping the setup operation at low cost, APP units provide quality pre-processing of chemical agents with subsequent delivery of activated materials onto the surface of interest. These units eliminate the need for vacuum chambers, simplify thermal control of the setup, and widen the range of applicable chemical precursors. Considering the above mentioned factors, the APP becomes a recognizable choice for industrial applications and laboratory use. Demonstrating advanced performance and possibilities, APP reactors are still a subject to certain challenges that have to be overcome with future research. Among them are clogging of output channels with processed material, accurate estimations of mixing zone for efficient material activation, and uniform on-demand distribution of activated material over the substrate. These problems are still waiting for elegant and effective solutions.

We investigate possibilities provided by use of a Linear Plasma Head — a portable APP reactor targeted for enhanced surface coatings. Currently we present our theoretical model of plasma generation in Linear Plasma Head. Numerical simulations are carried out using a parallel computational paradigm. The results and methods discussed in this paper yield with theory-based approach to building an advanced APP-based chemical reactor.
Numerical Study of Emulsion Droplet in Electromagnetic Field
Authors: Kovaleva Liana , Musin Ayrat , Fatkhullina Yulia , Zamula Yuriy , Zinnatullin Rasul , Akhatov Iskander S.
Published: October 2013

Some results of experimental studies of the water-in-oil emulsions in RF and MW electromagnetic fields are presented. In an attempt to understand the phenomenon a mathematical model for a single emulsion droplet dynamics in radio frequency (RF) and microwave (MW) electromagnetic fields is formulated. An algorithm for numerical solution of the problem is developed. The problem is solved accounting for the thermal motion induced by electromagnetic field in the fluid within the water droplet and in the surrounding liquid. The numerical solution revealed that the structures of arising convective flows induced by RF and MW electromagnetic fields are different. The results can help to understand the physical mechanisms of water-in-oil emulsion destruction in electromagnetic field.
Analysis of Heat Release Rate in the Partially Premixed Flame Structures During Autoignition of Unstrained, Laminar Mixing Layers
Authors: Awasthi Inkant , Gogos George
Published: October 2013

Autoignition in an unstrained, laminar mixing layer of methanol/air is investigated using detailed reaction mechanism and full multicomponent mass diffusion formulation. The temperature of the fuel stream is varied from 400 K to 1200 K, whereas the oxidizer stream is held at a fixed temperature of 1200 K. The calculations are performed for pressure p = 1 bar. Transient evolution of the autoignition kernel from initial partially premixed flame structures to final diffusion flame is demonstrated. The flame structures have been analysed for individual heat release rates. For equal fuel and oxidizer stream temperatures (1200 K), heat release in extremely fuel rich locations (with mixture fraction values up to 0.8) is found. A transient triple flame structure (two deflagrations and, one diffusion flame) is shown to exist even in cases when the temperature difference between the two streams is large. The heat release rates in the deflagrations depend on the temperatures of the two streams. When compared with the surviving diffusion flame, the heat release rate in the short-lived deflagrations is one to two orders of magnitude higher. It is shown that increasing the fuel stream temperature also decrease the ignition delay time in the mixing layer.
Pool Boiling of FC-87 Over Microchannel Surfaces at Atmospheric Pressure
Authors: Kalani Ankit , Kandlikar Satish G.
Published: October 2013

Advances in technology and trends towards higher processing speeds have generated a greater need for thermal management. Two-phase cooling (boiling) has the ability to dissipate large amounts of heat and is attractive because of lower mass flow requirement and uniform substrate temperature. Further improvements can be obtained through passive surface enhancements. The objective of this work is to investigate the effect of microchannel surfaces on pool boiling performance at atmospheric pressure with FC-87. Being a dielectric fluid with a low normal boiling point, FC-87 has desirable characteristics for an electronics cooling fluid. A maximum heat flux of 550 kW/m2 at a wall superheat of 37°C was obtained with the microchannel surface. Surface area increase is noted as the primary reason for the enhanced performance for FC-87 on microchannel surfaces.
Evaluation of Aerodynamic Infrasound Radiating From Upwind and Downwind HAWTs
Authors: Sescu Adrian , Afjeh Abdollah A.
Published: October 2013

A Computational Fluid Dynamics tool is used to determine the detailed flow field developing around two-blade horizontal axis wind turbines (HAWT) in downwind and upwind configurations. The resulting flow field around the wind turbine is used to evaluate the low-frequency noise radiating to the far-field, using an acoustic analogy method. The influence of the variation of wind velocity and rotational speed of the rotor to the sound pressure level is analyzed. This paper shows that the tower shadow effect of a downwind configuration wind turbine generates higher aerodynamic infrasound when compared to a corresponding upwind configuration. For validation, a comparison between numerical results and experimental data consisting of sound pressure levels measured from a two-blade downwind configuration wind turbine is presented.
Analysys and Optimization of Exit Burr Size and Surface Roughness in Milling Using Desireability Function
Authors: Niknam Seyed Ali , Kamguem Rene , Songmene Victor
Published: October 2013

The burr formation mechanism and surface quality highly depend on machining conditions. Improper selection of cutting parameters may cause tremendous manufacturing cost and low product quality. Proper selection of cutting parameters which simultaneously minimize burr size and surface roughness is therefore very important, as that would reduce the part finishing cost. This article aims to present an experimental study to evaluate parameters affecting the exit burr size (thickness and height) and surface roughness during milling of 6601-T6 aluminum alloy. Desirability function, Di(x), is then proposed for multiple response optimization. Optimum setting levels of process parameters are determined for simultaneous minimization of surface roughness and exit burr thickness and height. It was found that the changes in feed per tooth and tool geometry and coating have significant effects on variation of Di(x).
Dynamic Behavior of Different Grinding Wheel Hub Material in High Efficiency Deep Grinding (HEDG)
Authors: Tawakoli Taghi , Vesali Alireza
Published: October 2013

Machining accuracy and productivity of the grinding process can be mainly affected by the dynamic behavior of the different components participating in grinding process, e.g. grinding wheel, grinding machine and workpiece. Amongst others, design and material of the grinding wheels play a significant role in grinding performance. Therefore, controlling the dynamic behavior of the grinding wheel through an in-process monitoring and a post-process measurement seems an appropriate approach to optimize the grinding process, especially in high efficiency deep grinding (HEDG). This paper presents the results of the grinding tests, which were conducted using two different vitrified bonded CBN wheels — one with Carbon fiber-reinforced polymer (CFRP) hub body and other one with steel hub body. The experiments have been carried out using a new in-process measurement system which allows the detection of the wheel vibration amplitudes and frequencies in different location of the wheel body during grinding. It was proved that the dynamic behavior of grinding wheels can affect the chip removal mechanism. The experimental investigation showed that grinding parameters and coolant supply conditions in HEDG process can affect the dynamic behavior of the grindings wheels. Furthermore, using CFRP as the hub material leads to a reduction in the wheel vibration and generated amplitudes.
Bioadditive Manufacturing of Hybrid Tissue Scaffolds for Controlled Release Kinetics
Authors: Ozbolat Ibrahim T. , Khoda A. K. M. B. , Koc Bahattin
Published: October 2013

Development of engineered tissue scaffolds with superior control over cell-protein interactions is still very much infancy. Advancing through heterogeneous multifold scaffolds with controlled release fashion enables synchronization of regenerating tissue with the release kinetics of loaded biomolecules. This might be an engineering challenge and promising approach for improved and efficient tissue regeneration. The most critical limitations: the selection of proper protein(s) incorporation, and precise control over concentration gradient and timing should be overcome. Hence, tissue scaffolds need to be fabricated in a way that proteins or growth factors should be incorporated and released in a specific spatial and temporal orientation to mimic the natural tissue regeneration process. Spatial and temporal control over heterogeneous porous tissue scaffolds can be achieved by controlling two important parameters: (i) internal architecture with enhanced fluid transport, and (ii) distribution of scaffold base material and loaded modifiers.

In this research, heterogeneous tissue scaffolds are designed considering both the parameters. Firstly, the three-dimensional porous structures of the scaffold are geometrically partition into functionally uniform porosity regions and controlled spatial micro-architecture has been achieved using a functionally gradient porosity function. The bio-fabrication of the designed internal porous architecture has been performed using a single nozzle bioadditive manufacturing system. The internal architecture scheme is developed to enhance fluid transport with continuous base material deposition.

Next, the hybrid tissue scaffolds are modeled with varying material characteristics to mediate the release of base material and enclosed biological modifiers are proposed based on tissue engineering requirements. The hybrid scaffolds are fabricated for spatial control of biomolecules and base material to synchronize the release kinetics with tissue regeneration. A pressure-assisted multi-chamber single nozzle bioadditive manufacturing system is used to fabricate hybrid scaffolds.
Contact Ratio of Spatial Helix Gearing Mechanism
Authors: Chen Y.-Z. , Chen Z. , Zhang Y.
Published: October 2013

The contact ratio of spatial helix gear is deduced, and impacting factors of the contact ratio are analyzed. Then different design methods of contact ratio are discussed. The contact ratio could be designed flexibly. The theoretical gear ratio could be expanded to 36 with compact structure. The least tooth number of the driving wheel should be only 1. Numerical examples illustrate the design formula of contact ratio and the kinematics performance of the spatial helix gearing mechanism.
Modeling and Analysis of Cross-Flow Heat Exchanger Based on the Distributed Parameter Method
Authors: Lan Jiang , Zhu Lei , Zhao Jingquan
Published: October 2013

The cross-flow heat exchanger model based on distributed parameter method which could be applied further in a complex system simulation is established in this paper. Then both steady and transient simulations of a triangle plate-fin cross-flow heat exchanger are achieved. The conclusion indicates that there is a critical point, when the number of distributed elements continues to increase, errors can be neglected. In dry air condition, steady results are proved identical to the ones of the well-known effectiveness-NTU method. Transient simulations are also participated under both dry air and moist air conditions in the interest of discussing the dynamic performance of the heat exchanger, and latent heat shows a great influence on the outlet temperature in moist air condition. Moreover, the effect of fouling is studied as a modification. All the simulations are performed on the commercial software Flowmaster.
Design of Module for Modular Customized Manipulators
Authors: Singh Satwinder , Gupta Sameer , Singla Ekta
Published: October 2013

This paper proposes a design strategy for task-based customized manipulators in modular form. The motivation of work lies in the fact that with change in tasks or working environment, the configuration of robot in use may need significant changes. New set of robotic parameters can be designed from scratch or from the existing specifications. The work is an attempt to systematize this requirement of re-designing and development of customized robotic arms.
Catalytic Ignition Properties and Surface Reaction Kinetics Modeling From Methane in Oxygen-Nitrogen Mixtures on Platinum
Authors: Elgan Duane , Steciak Judi , Budwig Ralph , Beyerlein Steve
Published: October 2013

The ignition temperature and heat generation from oxidation of methane on a platinum catalyst were determined experimentally. A 127 micron diameter platinum coiled wire was placed crosswise in a quartz tube of a plug flow reactor. A source meter with a 4-wire measurement capability measured the resistance and current to calculate the average temperature of the surface reaction. Light-off temperatures varied from 730–780K for methane for a fuel-oxygen equivalence ratio of 0.3 to 1.0 at fuel percentages of 2–5% by volume. A model of the experimental system was created using Fluent coupled with Chemkin to combine an advanced chemistry solver with flow simulation. The experimental data was compared to the model results, which includes heat transfer and the surface reaction kinetics of methane on platinum. The heat transfer model obtained values within 4 Kelvin to experimental data for temperatures between 400K and 700K. At temperatures greater than 700K the model deviated with temperatures greater than the experimental by up to 60 Kelvin.
Using Numerical Simulation Tools to Assist the Development of a High Stability Low NOx Industrial Burner
Authors: Bao Ainan , Wang Dexin , Liss William
Published: October 2013

To achieve ultra low NOx emission as well as high efficiency for industrial burners, premixed or partial premixed combustion technology is becoming more attractive than flue gas recirculation approaches, which tend to cause low combustion stability and low energy use efficiency. A well designed premixed combustion system can achieve lower and more uniform combustion zone temperatures thus resulting in reduced thermal NOx generation. A multi-stage premixed industrial scale gas burner with oil backup capability has been developed by the authors, with the assistance from CFD simulation. By using staged combustion, combustion heat release is better distributed into a larger volume to avoid high peak flame temperature zone to occur. By using a primary stage combustion with a fuel rich flame and a hot high emissive metallic chamber wall, the burner combustion stability is ensured. The CFD tool was used to simulate and optimize the whole burner combustion and heat transfer process, with proper fluid dynamics and reaction models for this full size burner development. With the CFD efforts, the final burner design can achieve a very uniform temperature field, with peak flame temperatures below 1650°C, therefore thermal NOx generation is minimized. The numerical results show that this new gas-fired burner can achieve high efficiency with low NOx emission. Using the CFD simulation tool, the burner global parameters, such as its peak flame temperatures, its exhaust flue gas temperatures, and its NOx concentration distributions, have been studied under different burner operation conditions, e.g., different excess air levels, different burner firing rates, and different mixture inlet temperatures. The CFD simulation tool has been proved a good assistance for the burner design, as well as the burner performance optimization.
Characterization of Driving Patterns and Operations of Heavy Duty Vehicles in a Port Area and Their Influence on Exhaust Emissions and Fuel Consumption Evaluation Through Different Emission Models
Authors: Zamboni G. , Malfettani S. , André M. , Carraro C. , Marelli S. , Capobianco M.
Published: October 2013

An experimental and theoretical investigation is being performed with a view to evaluate the contribution of Heavy duty vehicles (HDVs) to exhaust emissions and fuel consumption in urban areas involved by commercial shipping activities.

Reference is made to the city of Genoa, whose urban road network is influenced both by shipping activities and highway connections, as more than twenty accesses to port area and seven motorway exits are available within the urban area.

Different aspects were deepened in this study. Firstly, the HDV flows crossing highway exits, urban zones and port areas were assessed, as well as the relevant vehicle classes. Secondly, the typical urban trips linking highway exits to port gates and the HDV mission profiles within the port area were identified. Measurements of HDV instantaneous speed related to the urban trips were then planned aiming at the definition of the most representative speed patterns through a proper statistical data processing, enabling the application of Passenger Car and Heavy Duty Emission Model (PHEM) for the estimation of emission and fuel consumption factors for selected HDV classes.

The main results of the different investigation steps are presented and discussed in the paper, outlining the peculiar mission of HDVs in port area and the related emissive behavior.
Effective Thermal Conductvity of Three-Phase Soils
Authors: Gori Fabio , Corasaniti Sandra
Published: October 2013

The aim of the present paper is to determine the effective thermal conductivity of three-phase soils, made of a quasi-spherical solid grain, and surrounded by two phase, which can be water and air or water and ice. The effective thermal conductivity is obtained theoretically by integrating the conduction equation under the thermal distribution of parallel heat fluxes in steady-state. The effective thermal conductivity is evaluated at a given degree of porosity (ratio between the void volume and the total one) and different degrees of saturation (ratio between the water volume and the void one) from dryness up to saturation. Comparisons between experimental data and theoretical predictions confirm that the present model can predict the effective thermal conductivity with a fairly good agreement without using any empirical constant.
Incorporating Public Policy Creation and Analysis Activities Into a Mechanical Engineering Curriculum
Authors: Reisel John R.
Published: October 2013

While it is easy to recognize that mechanical engineers can lend their expertise to public policy makers as they create public policy related to science and technology, it is not as clear as to how to introduce mechanical engineering students to public policy activities. The undergraduate curricula in most mechanical engineering programs are considered full, and there are always additional topics that people wish to add. Educators are likely to hesitate before removing material from their programs in order to add material on public policy. Yet, there are techniques that can be used to incorporate aspects of public policy into a standard mechanical engineering curriculum without the removal of much, if any, current content.

In this paper, several techniques for introducing mechanical engineering students to the process of public policy creation will be discussed. While these methods will not make the students experts in policy, they can introduce students to the tools that they need to influence the public policy creation process. These techniques include a comprehensive semester-long project in a technical elective course, a short policy analysis paper for development in a required or elective course, incorporation of public policy considerations in a capstone design project, policy discussions or debates in relevant courses, and a focus on public policy development in extracurricular activities.

In their education, students should not only become technically proficient, but also learn how to track current events and trends, communicate their knowledge effectively, gain knowledge on applying proper engineering ethics, and be aware of the environmental and social context of their work. Through these knowledge areas and skills, students will gain the fundamental working knowledge that they need to influence public policy creation. It may be noted that these are also desirable outcomes for a student’s educational program as defined by ABET. Therefore, finding opportunities in a mechanical engineering program’s curriculum to address public policy creation activities also benefits the program by helping it more completely fulfill ABET accreditation requirements.
Design and Analysis of Composite Ocean Current Turbine Blades Using NREL Codes
Authors: Zhou Fang , Mahfuz Hassan , Alsenas Gabriel M. , Hanson Howard P.
Published: October 2013

Ocean current energy is at an early stage of development — a vital component in that is the design and analysis of turbine blades that would be used to generate the power. The ocean current turbine (OCT) is similar in function to wind turbines, capturing energy through the processes of hydrodynamic, rather than aerodynamic, lift or drag. OCT operates on many of the same principles as wind turbines and share similar design philosophies. NREL (National Renewable Energy Laboratory) has extensively investigated the design of wind turbine blades over the years and many codes have been developed. It is meaningful and prudent to take advantage of those codes and use them in the design of OCT blades. Currently available codes such as FoilCheck, PreComp, BModes, AeroDyn, FAST, etc. provides an excellent dynamic analysis of hollow composite wind turbine blades. Since OCT blades have PVC foam as core materials inside the skin, NREL codes could not be used directly. These core materials for the blade were necessary to fulfill the buoyancy requirement at ocean depth. A set of methods was therefore developed to design and analyze OCT blades where most of NREL codes could be utilized. The methods are as follows: DesignFOIL was first used to generate hydrofoil geometry (coordinates), and lift and drag coefficients for selected blade sections. FoilCheck was then used to calculate hydrofoil data for the entire range of ±180°. FoilCheck output files were later used as input for AeroDyn. In the next step, PreComp computed the section properties for the hollow composite OCT blade. Section properties of the core material such as extensional stiffness, flexural rigidity, and torsional rigidity were calculated separately and added to the properties computed by PreComp. Mode shapes and frequencies of OCT blades were computed using BModes. AeroDyn calculated the hydrodynamic lift and drag forces for the hydrofoil sections along the blade. In AeroDyn input file, kinematic viscosity, density and velocity were set to the values of seawater @ 1.05×10−6 m2/sec, 1025 kg/m3, and 1.7 m/s, respectively. Finally, FAST was used to obtain the dynamic response of three-bladed, conventional, horizontal-axis OCT. However, this analysis did not provide any stress calculations. In order to perform stress analysis, NuMAD code developed by Sandia National Laboratory was incorporated in the method. This allowed us to create ANSYS input files. Loads calculated by AeroDyn were then transported to ANSYS and a complete stress analysis was performed. Critical regions of stress concentration were identified — opening up an opportunity for materials failure and fatigue analysis. In summary, coupling of NREL codes, NuMAD, and ANSYS revealed a path way to achieve comprehensive design and analyses of OCT blades.
Bridging Academia and Industry Gap, Through Global Competencies: Industrial Outreach Program US-Mexico
Authors: Mucino Victor H. , Lozano Guzmán Alejandro A. , Alcázar Farías Edna Karina , Sanchez-Goni Elisabeth , Aguilera Navarrete Israel
Published: October 2013

Global competencies of engineering graduates have been identified as traits that are increasingly necessary for professional competitiveness of graduates, but continue to be elusive and difficult to address in the engineering curricula. Study abroad and experiential learning programs have been invoked to address some of the global competencies with varied degrees of success. In this paper, a faculty-led program model developed by West Virginia University and several institutions in Mexico and the US is presented, in which senior engineering students from the US and Mexico team up to conduct meaningful engineering projects in industry in Mexico. Intermixed teams of students are formed and placed in various industrial sites to work full time under the advice of engineering practitioners and faculty members from both Mexico and USA. Global competencies are addressed in the context of a project that requires students to work with peers of similar disciplines and level across language and cultural barriers.
Modeling and Characterization of Strain Sensing in CNT-Based Polymer Composites Under Tensile Loading
Authors: Kuronuma Yu , Takeda Tomo , Shindo Yasuhide , Narita Fumio , Wei Zhijuan
Published: October 2013

This paper presents a study on the strain sensing behavior of carbon nanotube (CNT)-based polymer composites subjected to tensile loading. Tensile tests were performed on CNT/polycarbonate composites and the responses in strain and electrical resistance were measured during the tests. An analytical model incorporating the electrical tunneling effect due to the matrix material between CNTs was also developed to predict the electrical resistance change resulted from deformation. The analytical predictions were compared with the experimental data.
Pump Using Nematic Liquid Crystalline Flow Under Direct Current Electric Field
Authors: Miyahara Kohei , Kodama Kenta , Tsukiji Tetsuhiro
Published: October 2013

This paper presentsa small pump for liquid crystal, herein called a liquid crystal pump. The mechanism of liquid crystalline flow by applying an electric field to the liquid crystal is used to generate one-directional flow in a pump. A liquid crystal pump has a cylindrical channel and a cylindrical electrode pair. In this study, direct current electric fields were used, and the pressure-flow rate characteristics of the pump were measured. In addition, the relationships between the non-dimensional flow rate and pressure of the pump were obtained. In order to achieve both high pressure and high flow rate, various shapes of electrodes and channels were investigated and the measured results were compared with each other. In addition, connecting pumps were designed to obtain the required pressure and flow rate. The structure of a liquid crystal pump is simple and the size can be decreased by further research. So this pump has the advantage of small source of actuator by changing electric power into fluid power. Furthermore, our pump has a good possibility for use in cooling system because it makes no noise and no mechanical vibrations.
Experimental Studies on Wake-Induced Transition of Turbulent Boundary Layers
Authors: Takeuchi Keiji , Fujimoto Susumu , Koyabu Eitaro , Tsukiji Tetsuhiro
Published: October 2013

Wake-induced bypass transition of boundary layers on a flat plate subjected to favorable and adverse pressure gradients was investigated. Detailed boundary layer measurements were conducted using two hot-wire probes. A spoked-wheel-type wake generator was used to create periodic wakes in front of the flat plate. The main focus of this study was to reveal the effect of the Strouhal number, which changed by using different numbers of wake-generating bars, on the turbulence intensity distribution and the transition onset position of the boundary layer on the flat plate using two hot-wire probes.
Effectiveness of Problem Solving Software in Engineering Conceptual Design
Authors: Bzymek Zbigniew M. , Xu Yang
Published: October 2013

The process of generating the most attractive product concepts in engineering design is still one of the greatest challenges of the 21st century. There are several tools for supporting this extremely uncontrollable phase of engineering design. Except for the method, the problem-solving software is the very important tool. One of the most useful methods in teaching and learning, i.e. Brief Theory of Inventive Problem Solving (BTIPS), is discussed in other papers [1], [2], [3] and [4]. This paper is devoted to the software supporting the problem solving process. There is still no software suitable for a completely satisfactory automation of the conceptual design process. However there are some software packages that could be the most helpful in supporting the process and would greatly influence the quality of the final product, especially in cases of contradicting constraints. In this paper some results of the research on the use and effectiveness of Invention Machine (IM™) software products are described. Four packages are discussed and compared: the IM v. 2 for Windows, TechOptimizer v. 3.5, TechOptimizer v. 4.0 and Goldfire v. 6.5. Goldfire v. 6.5 evaluation is still in the process and is not completely finished yet. The first three packages were used in teaching several junior, senior and graduate courses at the University of Connecticut (UConn) for many years. The experience with Goldfire v. 6.5 is comparatively limited. In the research described in this paper the content and the teaching effectiveness of the software packages in teaching were studied. Data from student feedback was evaluated, conclusions were derived. On the basis of this - recommendations for the future use of the software are offered. This paper concentrates on some instrumental software qualities that could be used in teaching of solving problems of industrial products conceptual design. The user’s experience and its connection with the effectiveness of the packages used are discussed in the paper. Conclusions are derived at the end.
Impact of Thermal Transport on Silicon Carbide Formation/Engulfment During Directional Solidification of Si
Authors: Ma Xu , Zhang Hui , Zheng Lili
Published: October 2013

This paper investigates thermal transport on SiC formation and engulfment in directional solidification of crystalline Si. A comprehensive computational model is developed which is capable of describing fluid and thermal transport, SiC particle formation/transport, and its pushing-engulfment near the solidification interface. It is found that the impurity of carbon concentration in the melt is affected by melt convection; the concave interface leads to the carbon accumulation in the central region near the interface; the size of the SiC particle when engulfed into solid Si is mainly determined by the solidification rate. The distributions of carbon concentration and SiC particles are determined by both melt convection, interface shape and solidification rate. The low solidification rate is not desirable for high quality Si crystal growth when the solid/liquid interface is concave.
Multi-Objective Design Optimization of Crash Energy Absorbers
Authors: Kamel Hesham
Published: October 2013

Crash energy absorbers are important structure elements for mitigating the harmful effects of accidents on the occupants. In the present work, multi-objective optimization is applied for improving the design of crash energy absorbers. A case study is presented of a crash energy absorber. Response surface models of important responses such as amount of absorbed impact energy and maximum reaction force are developed. The proposed approach offers the designer with a practical tool for improving structure designs undergoing nonlinear behavior.
An Investigation Into the Influence of Ultrasonic Servo Feed Drive Technology in Electro Discharge Machining Industrial Applications
Authors: Shafik M.
Published: October 2013

This paper demonstrates the investigation carried out into the influence of ultrasonic servo feed drive technology, in electro discharge processing systems, industrial applications. The drive was mainly designed to replace the existing servo control drive using electromagnetic servo technology. This was aimed to improve the electro discharge servo control system stability, quality of the machined products surface profiles, and system dynamic time response. Evaluation has been undertaken to examine the developed servo control feed drive, in two industrial applications, electro discharge machining and electro discharge texturing. Two arrangements were used, in this investigation. The existing servo control feed drive system, which uses electromagnetic servo drive, and the developed system, which uses piezoelectric ultrasonic feed drive. The electro discharge processing parameters, including current level, the on-off time and the duty cycle of the machining pulse were the main processing parameters of this investigation. The electron microscopic micro examination into the machined and textured samples showed that: piezoelectric ultrasonic feed drive showed a clear improvement in the quality of surface finish of the machined samples, due to the fast dynamic time response of the developed drive. This was accompanied with a notable reduction in the arcing and short-circuiting teething phenomena. This was verified by assessing the electrode movements, the variations in the inter electrode gap voltage, current and feedback control signals.