bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Investigation on Vertical Axis Wind Turbine in Search for an Efficient Design
Authors: Rahman Mosfequr , Bashar Mohammad , Molina Gustavo , Soloiu Valentin , Salyers Travis
Published: March 2016

The continuous improvement of this world is based on technological advancement. And the technological advancement is directly related to the utilization of energy. The demand of energy is creeping up every day due to increase of population, industrial and agricultural advancement. But the conventional energy sources are becoming limited which is ultimately making them more expensive. In addition to this, everyone is concerned about global climate change. This whole scenario is pushing the world to find the alternative sources of energy. Alternative sources involve natural phenomena such as sunlight, wind, tides, plant growth, and geothermal heat. Solar and Wind power are the most popular among the various sources of renewable energy.

Wind alone can fulfill most of the energy requirement of the world by its efficient conversion in to energy. Though Horizontal Axis Wind Turbine (HAWT) is more popular but needs high wind speed to extract energy from the wind. On the Other hand Vertical Axis Wind Turbine (VAWT) can run at low wind speed, independent of wind direction and can be installed anywhere with cheapest cost. The main objective of this research is to improve the design and performance of VAWT to make it more attractive, efficient, durable and sustainable. For a VAWT, the blades perform the main role to extract energy from the wind. Airfoil is considered as the blade for this new design of VAWT. Airfoil has some good aerodynamic characteristics, matches with the characteristics of Savonious type VAWT, such as good stall characteristics and little roughness affect, relatively high drag and low lift coefficient. Three dimensional CAD models of various simple airfoils have been designed in Solidworks. Using these airfoils CFD simulation has been performed for five different VAWT designed models. Moving mesh and fluid flow simulation have been performed using CFD software FLUENT. The findings of these numerical simulations provided pressure contour, velocity contour, drag coefficient, lift coefficient, torque coefficient and power coefficient for all these models. From the results it can be concluded that NACA7510 airfoil VAWT model gives the better performance at higher Tip Speed Ratio (λ) than other models.
Mixed Convolved Action Principles for Dynamics of Linear Poroelastic Continua
Authors: Darrall Bradley T. , Dargush Gary F.
Published: March 2016

Although Lagrangian and Hamiltonian analytical mechanics represent perhaps the most remarkable expressions of the dynamics of a mechanical system, these approaches also come with limitations. In particular, there is inherent difficulty to represent dissipative processes and the restrictions placed on end point variations are not consistent with the definition of initial value problems. The present work on poroelastic media extends the recent formulation of a mixed convolved action to address a continuum dynamical problem with dissipation through the development of a new variational approach. The action in this proposed approach is formed by replacing the inner product in Hamilton’s principle with a time convolution. As a result, dissipative processes can be represented in a natural way and the required constraints on the variations are consistent with the actual initial and boundary conditions of the problem. The variational formulations developed here employ temporal impulses of velocity, effective stress, pore pressure and pore fluid mass flux as primary variables in this mixed approach, which also uses convolution operators and fractional calculus to achieve the desired characteristics. The resulting mixed convolved action is formulated in both the time and frequency domains to develop two new stationary principles for dynamic poroelasticity. In addition, the first variation of the action provides a temporally well-balanced weak form that leads to a new family of finite element methods in time, as well as space.
Influence of Ignition Timing and EGR on the NOx Emission and the Performance of an SI Engine Fueled With Hydrogen
Authors: Khairallah Hassan A. , Vaz Warren S. , Koylu Umit O.
Published: March 2016

Exhaust gas recirculation (EGR) and ignition timing have strong effects on engine performance and exhaust emissions. In the present study, detailed chemical reactions with 29 steps of hydrogen oxidation with additional nitrogen oxidation reactions were coupled with an advanced CFD code to investigate the engine performance and emission characteristics of a SI engine fueled with hydrogen. The NOx formation within the engine was computed using the extended Zeldovich mechanism with parameters adjusted for a carbon-free fuel such as hydrogen. The computational results were validated against experimental results with equivalence ratio of 0.84 and fixed ignition timing at crank angle of 5° BTDC (before top dead center). The simulations were then employed to examine the effects of EGR and ignition timing on the engine performance and NOx formation and emission. The EGR ratio was varied between 5% and 15% while the ignition timings considered were 5°, 10°, 15°, and 20° BTDC. It was found that NOx emission increased with advancing the ignition timing away from TDC while the indicated engine power showed an increasing trend with further advancing the ignition timing. Higher indicated mean effective pressure (IMEP) and indicated thermal efficiency were obtained with an advanced ignition timing of 20° BTDC. The model was also run with three different EGR ratios of 5%, 10% and 15% with fixed ignition timing at 5° BTDC. The simulation results quantified the reduction in NOx and the indicated engine power with the increase in the EGR ratio. The computations were consistent with the hypothesis that the combustion duration increases with the EGR ratio. Finally, the maximization of engine power and minimization of NOx emissions were considered as conflicting objectives. The different data points were plotted in the objective space.

Using the concept of “knee”, (5° BTDC, 0% EGR) was selected as the optimal operating point representing the best trade-off between maximum engine power and minimum NOx emissions.
Numerical Analysis of Transient Temperature Distribution in a Partially Cooled Nuclear Fuel Rod
Authors: Patil Sandeep , Chintamani Siddarth , Kumar Rajeev , Kumar Ratan , Dennis Brian H.
Published: March 2016

Critical safety studies of a nuclear power plants are often associated with inadequate and improper cooling of the reactor core or the spent fuel rods. Coolant flow over the hot nuclear fuel rods often gets stalled during major accidents resulting in high temperature levels. These elevated temperature levels can potentially melt the fuel rod material and cause the release of radioactive gases. Research activities, both numerical and experimental in nature to explore these rare but potentially catastrophic possibilities have resulted in sophisticated numerical codes capable of simulating the various post-accident scenarios. These codes, although reasonably accurate and reliable have steep learning curves and are not often very user-friendly. A fast and accurate prediction of the critical temperature conditions using popular commercially available software packages is the subject of current study.

Results from this parametric study of temperature distribution over a partially cooled fuel rod carried out using ANSYS as the numerical analysis tool is reported. Nuclear fuel rods being inadequately cooled inside a stagnant pool of coolant water in an accident scenario resulting in disrupted coolant flow has been simulated. This situation can arise within the reactor (design-basis accidents) or in the waste-fuel storage (as faced in Fukushima). In these situations, the fuel rod is often left partially immersed in the coolant water resulting in immersed portion of the rod cooled by water and the exposed portion cooled by air leading to non-uniform and improper cooling of the system.

Realistic dimensions and materials as in commercial nuclear fuel rod have been used in the study. Taking advantage of the symmetry, an axisymmetric radial plane sliced longitudinally has been analyzed. Variations in the tangential direction have been neglected. The heat transfer problem uses homogeneous convective boundary conditions and assumes temperature dependent thermal conductivity. The parameters varied are the coolant level and the heat generation rate inside the fuel rod. A macro to automatically capture the transients in the temperatures was written in ANSYS (a finite element package). The governing energy equations were implicitly solved using finite volume scheme in MATLAB. ANSYS results are in close agreement with those obtained using MATLAB. The centerline temperature of the fuel rod shows a sharp rise below a certain coolant level.
Determining Probability of Importance of Features in a Sketch
Authors: Cruz-Lozano Ricardo , Alemayehu Fisseha M. , Ekwaro-Osire Stephen , Endeshaw Haileyesus
Published: March 2016

Sketches are the main tools for the communication of concepts among design team’s members during the ideation phase of the design process. Imprecisely defined sketches lead to uncertainty in communication during the design process. Thus, as a contribution to reduce the uncertainty in design communication, an initial framework for the quantification of uncertainty associated to sketches was presented in previous work. In that initial framework, the probabilities of the features in a sketch were determined based on the assessment of an experienced designer. This approach reduced the usability of the framework by professionals with limited experience e.g. entry-level engineers. Thus, this posed the need of an improved framework and brought the following research question: Can a probabilistic method be used to improve the quantification of uncertainty in sketches? Accordingly, to answer this research question the following specific aims were established: 1) Ranking of features in a sketch, 2) Determination of the probability of importance of features in a sketch, and 3) Quantification of uncertainty in a sketch. The first aim focused on determining and classifying the features in a sketch, based on a hierarchical approach. The second aim focused on determining the probability of importance of the features in a sketch, by assessing its probability of likeliness using an object recognition approach, and by applying a probability transformation. The third aim focused on the quantification of the uncertainty in a sketch, based on the calculation and normalization of the sketch’s entropy. This resulted in the development of an improved framework for the quantification of uncertainty in sketches, which can be used by design practitioners with limited experience, and whose application is presented and detailed in a case study.
Design and Development of Virtual Reality Environments for Biomedical and Engineering Applications
Authors: Govea Eder , Medellín-Castillo Hugo I.
Published: March 2016

Virtual Reality (VR) is one of the areas of knowledge that have taken advantage of the computer technological development and scientific visualization. It has been used in different applications such as engineering, medicine, education, entertainment, astronomy, archaeology and arts. A main issue of VR and computer assisted applications is the design and development of the virtual environment, which comprises the virtual objects. Thus, the process of designing virtual environment requires the modelling of the virtual scene and virtual objects, including their geometry and surface characteristics such as colours, textures, etc.

This research work presents a new methodology to develop low-cost and high quality virtual environments and scenarios for biomechanics, biomedical and engineering applications. The proposed methodology is based on open-source software. Four case studies corresponding to two applications in medicine and two applications in engineering are presented. The results show that the virtual environments developed for these applications are realistic and similar to the real environments. When comparing these virtual reality scenarios with pictures of the actual devices, it can be observed that the appearance of the virtual scenarios is very good. In particular the use of textures greatly helps in assessing specific features such as simulation of bone or metal. Thus, the usability of the proposed methodology for developing virtual reality applications in biomedical and engineering is proved. It is important to mention that the quality of the virtual environment will also depend on the 3D modelling skills of the VR designer.
‘Acoustic Fiber’ Aluminum-Clad Copper Cable for Communication and Power Transmission
Authors: Litman R. B. , Scarton H. A. , Wilt K. R. , Saulnier G. J.
Published: March 2016

An ‘acoustic fiber’, analogous to optical fiber, is presented as a means of long-distance data and energy transfer. Low-loss axial guided waves are produced along a cable-like waveguide, which is composed of a solid core and a cladding layer, where the cladding’s acoustic speeds of sound, both longitudinal and transverse, exceed those of the core. A similar condition exists in glass fiber optic cables consisting of a core surrounded by a cladding of lower index of refraction. This results in total internal reflection of light at the core-cladding interface and effective confinement of light to the core. A specific acoustic waveguide construction is analyzed, composed of an aluminum cladding with longitudinal wave speed of 6.198 km/s and shear wave of 3.122 km/s and copper core with longitudinal speed of 4.505 km/s, and shear speed of 2.164 km/s. Finite element simulations show that a guided wave mode that is confined largely to the core exists and is capable of propagating long distances with very little loss to the surroundings.

A 6 mm diameter aluminum-cladded copper core (2 mm diameter) fiber was found to have a propagation loss of 0.023 dB/m when operating at 2 MHz predict (neglecting material attenuation). When including material attenuation, the same waveguide produced a propagation loss of 0.24 dB/m. Similarly, a 12 mm cladding with 4.8 mm core at 1 MHz had losses of 0.10 dB/m, and a 22 mm diameter cladding with 9 mm core at 500 kHz had losses of 0.062 dB/m.

Relationships were found between frequency, total diameter and core diameter yielding the highest efficiencies. The minimum total dimension of an aluminum-clad-copper acoustic fiber was found to have an inverse relationship with frequency. The optimum ratio of core to total diameter was about 0.45 but between values of 0.35 and 0.5, attenuation was relatively constant (insensitive to frequency). Outside of that range, attenuation climbed rapidly. Due to this property, attenuation in properly designed fibers should always be dominated by, and roughly equivalent to, the material attenuation rather than attenuation due to leakage.
Numerical Simulation for 3-D Wind Fields in Suburban Environment With Topographic Effects
Authors: Zhang Rui , Wang Xiuling
Published: March 2016

3D wind field construction is important in many aspects, such as wind energy assessment, wind turbine siting and weather forecasting. The development of Computational Fluid Dynamics (CFD) 3D wind flow over complex terrain and boundary conditions in simulation has been studied intensively over past thirty years. However, the topographical effects has seldom been considered in the 3-D wind field construction in suburban environment. In this paper, 3-D wind field is constructed with consideration of terrain effects. 3-D terrain flowing mesh is built from digital elevation data (DEM) by in house codes. The Reynolds-averaged Navier-Stokes equations are solved by the standard k-ε turbulence model with Ansys Fluent©. The integration between the topographical effects and 3D wind field in suburban environment is investigated. Simulation results of 3-D wind field, wind velocity distributions, turbulence intensity distributions, wind power density distributions and wind profiles are obtained around Purdue University Calumet (PUC) campus. Additionally, the surround building effect and topographical effect are discussed. The simulation results are validated against measurements data.
Numerical Investigation Into the Thermal Performance of Two-Layered Microchannels With Varying Axial Length and Temperature Dependent Fluid Properties
Authors: Adewumi Olayinka O. , Bello-Ochende Tunde , Meyer Josua P.
Published: March 2016

This study numerically investigates the thermal performance of a two-layered microchannel heat sink with varying axial length, varying solid substrate aspect ratio (ratio of height to width of the silicon solid substrate) but with a fixed total volume constraint and water as the working fluid. The optimal geometry in terms of channel hydraulic diameter, channel aspect ratio and the solid substrate aspect ratio was selected based on the minimised peak temperature on the heated base of the solid substrate with a constant heat load of 100W. The optimal aspect ratio AR of the solid substrate was discovered to be 4 for all pressure drop range considered in this study but the optimal axial length shows a dependence on pressure drop. Results of the effect of varying axial length on surface heat flux, minimised thermal resistance and temperature variation on the heated base of the solid substrate were also presented and discussed.
Elastic Dispersion Analysis of Two Dimensional Phononic Crystals Composed of Auxetic Materials
Authors: Liu Geng-Ting , Tsai Chia-Nien , Chang I-Ling , Chen Lien-Wen
Published: March 2016

The wave propagations of two dimensional phononic crystals composed of auxetic materials are studied. The periodic structures consist of square lattice air cylinders in a solid background made of auxetic material. The finite element method and plane wave expansion method are used to obtain the band structures of the phononic crystals. The effects of Poisson’s ratio on the elastic wave propagation within the phononic crystal are investigated. The negative Poisson’s ratio of the auxetic material is shown to have significant effect on the dispersion of the elastic wave within the periodic structures. The results reveal that the phononic crystals composed of auxetic materials can have a great potential for the design of novel acoustic devices.
Damage and Anisotropy Evolution in the Free End Shear Problem
Authors: Kweon Soondo , Raja Daniel S.
Published: March 2016

The evolution of microstructure occurs in the deformation of metals via texture evolution. The effect of the microstructural evolution, i.e., anisotropy evolution, on the free end shear problem is investigated. An anisotropic ductile fracture model that takes into account the evolution of the orthotropic axes in the matrix is employed to perform the above task. With the model, a well-known experiment that provides the evidence of anisotropy evolution, the free end cyclic torsion test, is simulated. For the simulation of the free end cyclic torsion test, an explicit numerical scheme for the free end shear simulation is proposed and performed to reproduce the experimental result of the free end torsion test. The simulation result reveals the physics of the shear damage process, which is that porosity evolves in the shear deformation of (induced) anisotropic materials due to the evolution of anisotropy. A series of the free end shear simulations reveal the effect of the interaction among the matrix anisotropy, porosity and void shape onto the deformation pattern and the ductile damage process of porous materials.
Finite Element Analysis of Various Projectiles Modeled as Bullets
Authors: Rahman Mosfequr , Chrysosferidis Steven , Salekeen Sirajus , Chevalier Adam , Bell David , Jones Bowen , Barlow Adam
Published: March 2016

The objective of this research work was to perform a flow simulation around a running bullet and then compare and analyze three types of widely used bullet models. These are 7.62mm × 39mm, 7.62mm × 51mm, and 5.56mm × 45mm caliber popular NATO rounds respectively. Due to limited processing and computational resources, these bullet are modeled as cylindrical projectiles of similar length and diameter. Finite element analysis (FEA) are performed on these models using ANSYS explicit dynamics analysis code to investigate the effect of high velocity impact of these projectiles on a concrete plate. Three different types of meshing (coarse, fine, and fine with curvature) for each of these three cases have been used. Each projectile was fired at a different velocity. These velocities are selected in consultation with Hornady Manufacturing, Inc which has done extensive research on these bullets. The selected firing velocities for 7.62mm × 39mm, 7.62mm × 51mm, and 5.56mm × 45mm caliber bullets are 2021ft/s, 2539.4ft/s 2706.7ft/s respectively.

Overall, the simulation result of explicit dynamics clearly demonstrated cavitation and mushrooming of projectiles when impacting a 0.25 inch concrete plate. The 5.56mm × 45mm projectile seemed to have the largest overall total deformation values of 2.0303, 1.0487, and 0.26079 feet as obtained from simulation of the three types of mashing. This can be attributed due to the higher velocity (2706.7ft/sec) as compared to the other two cases. Similarly, the 7.63mm × 39mm has the highest average change of velocity of 144.7, 92.3, and 99.6ft/sec respectively from the three types of meshing among the three bullets which can be attributed due to its lowest impact velocity (2021ft/s).
Design and Development of Sonotrode for Ultrasonic Drilling
Authors: Tadvi Mihir , Pandey Akash , Prajapati Jagdish , Shah Jimil
Published: March 2016

The design of tooling for ultrasonic machine is critical for every application. For the proper concentration of energy across the workpiece during ultrasonic machining, geometry of sonotrode plays important role. The entire ultrasonic assembly has to be tuned to the same frequency for transfer of maximum energy. If the natural or resonant frequency of the components in the ultrasonic assembly are different, it would set up vibrations of different frequencies leading to energy loss and even damage to certain components by fatigue at the interface surfaces. The issues involved in sonotrode design are material, shape, frequency, resonant length and gain. Proper design of sonotrode is essential to bridge the gap between the booster and the work surface and amplify the vibration amplitude to a value required for successful machining. The separate design of tool which can be assembled at the end of the sonotrode leads to acoustic coupling problems at that interface and separate design of sonotrode and tool and individual testing for successful tuning on the machine. It increases the possibility of failure also. For these reasons, the integrated design of sonotrode with tool being formed at the bottom end of sonotrode is preferred. The tool edge is so designed that only the periphery of the hole is to be cut to obtain through drilling. This reduces the amount of material to be removed and the machining time. The manual design procedure would require solving a second order partial differential equation with the boundary conditions applicable to the machine and the gain required. This paper discusses design of conical, exponential and step-cylindrical horn for ultrasonic machining. First the dimensions are obtained through commercial sonotrode design software CARD (Computer Aided Resonator Design). The software uses the finite difference theory for discretising the sonotrode along the length and iteratively finds the length for resonance condition with gain close to the required amplification provided by the user. It also gives the nodal point, anti-nodal point, stress variation and amplitude variation along the axis of the sonotrode over the entire length. End diameter and resonant length calculated from CARD are supplied to ANSYS to perform modal analysis. A good agreement is observed between the results obtained using CARD software and ANSYS. Based on this design, actual horn of the conical design is manufactured and tested on the machine for resonant frequency and the results are found to be close to those observed from CARD and ANSYS both.
The Effects of Retraction on Primary Atomization in a Pulsating Injector
Authors: Strasser Wayne , Battaglia Francine
Published: March 2016

Despite its industrial relevance, the exploration of primary atomization within a transonic self-generating pulsatile three-stream injector has been minimal. Our prior experimental and computational work was centered around compressible axisymmetric (AS) models and incompressible 3-D models for the purpose of obtaining spectral content and preliminary droplet size distributions. Here, the emphasis shifts to compressible 3-D computational models involving a non-Newtonian slurry and a much more inclusive computational domain in order to further elucidate droplet size information. Effects of numerics, turbulence model, and geometric parameters are revisited. In addition, a surrogate measure for injector face erosion is introduced. Lastly, links are discovered between responses in Sauter mean diameter and trends in AS modeling metrics. As with prior air-water work and incompressible slurry simulations, higher gas inner flow rate reduced droplet size measurably. While the temporal mean droplet length scale was relatively insensitive to numerics, turbulence model, compressibility, and modeled domain size, droplet size temporal variability responded very strongly to some of these effects; compressibility dampened the droplet variability, while increased inner gas flow augmented variability, and the use of a more rigorous turbulence model showed a mixed effect. It was found that designs with less retraction (smaller pre-filming region) produced smaller droplets and allowed increased process throughputs. Newly discovered correlation equations are provided and followed similar trends as some from the earlier AS work. Interestingly, it was also shown that droplet size can be correlated with spectral information from prior companion AS studies.
Effect of Morphology on Wave Propagation in Porous Materials
Authors: Aksoy Huseyin G.
Published: March 2016

In this study, effect of morphological parameters on wave propagation in bicontinuous porous nanostructures is studied by using numerical simulations. Computational results show that energy is localized on the surface independent of the morphological parameters. It is observed that localization length increases with the increase in frequency. In addition, surface roughness parameter and ligament diameter do not have significant influence on localization length.
Effect of Boron Nitride on the Mechanical and Electrochemical Properties of Cement Composite
Authors: He Qinyue , Yu Xun
Published: March 2016

Hexagonal boron nitride (h-BN) is well known for its unique properties, such as high thermal conductivity, excellent mechanical strength, high electrical insulating, and high chemical stability. This paper studies the effect of h-BN to the mechanical and electrochemical properties of cement concrete. Sodium cholate is used as an ionic surfactant to exfoliate h-BN and subsequently stabilize them in water solution. Different cement concrete samples with different doping levels of h-BN and different sizes of h-BN were prepared for comparisons. Also, steel fiber reinforced h-BN/cement concrete samples were also prepared. The results show that the addition of h-BN can improve the strength of cement composites, and the degree of reinforcement are influenced by the doping levels and feature size of h-BN. The corrosion resistance of h-BN/cement composites were also tested. Experiments results show that h-BN can enhance the corrosion resistance of cement composites.
Hydrogen Diffusion and Segregation in Alpha Iron ∑ 3 (111) Grain Boundaries
Authors: Hamza Mohamed , Hatem Tarek M. , Raabe Dierk , El-Awady Jaafar A.
Published: March 2016

Polycrystalline material generally exhibits degradation in its mechanical properties and shows more tendency for intergranular fracture due to segregation and diffusion of hydrogen on the grain boundaries (GBs). Understanding the parameters affecting the diffusion and binding of hydrogen within GBs will allow enhancing the mechanical properties of the commercial engineering materials and developing interface dominant materials. In practice during forming processes, the coincidence site lattice (CSL) GBs are experiencing deviations from their ideal configurations. Consequently, this will change the atomic structural integrity by superposition of sub-boundary dislocation networks on the ideal CSL interfaces. For this study, the ideal ∑ 3 111 [110] GB structure and its angular deviations in BCC iron within the range of Brandon criterion will be studied comprehensively using molecular statics (MS) simulations. The clean GB energy will be quantified, followed by the GB and free surface segregation energies calculations for hydrogen atoms. Rice-Wang model will be used to assess the embrittlement impact variation over the deviation angles. The results showed that the ideal GB structure is having the greatest resistance to embrittlement prior GB hydrogen saturation, while the 3° deviated GB is showing the highest susceptibility to embrittlement. Upon saturation, the 5° deviated GB appears to have the highest resistance instead due to the lowest stability of hydrogen atoms observed in the free surfaces of its simulation cell. Molecular dynamics (MD) simulations are then applied to calculate hydrogen diffusivity within the ideal and deviated GB structure. It is shown that hydrogen diffusivity decreases significantly in the deviated GB models. In addition, the 5° deviated GB is representing the local minimum for diffusivity results suggesting the existence of the highest atomic disorder and excessive secondary dislocation accommodation within this interface.
Experimental Investigations on DI Diesel Engine With Low Heat Rejection Combustion Chamber With Waste Fried Vegetable Oil and its Biodiesel
Authors: Chowdary Raavi Peraiah , Krishna Maddali V. S. Murali , Reddy T. Kishen Kumar , Srikanth D. , Murthy P. V. Krishna , Janardhan N.
Published: March 2016

Biodiesels derived from vegetable oils present a very promising alternative fuels for diesel fuel, since they have numerous advantages compared to fossil fuels. However crude vegetable oil and biodiesel have high viscosity and low volatility causing combustion problems in CI engines, call for engine with hot combustion chamber. Investigations were carried out on single–cylinder, four–stroke, water cooled, 3.68 kW direct injection diesel engine at a speed of 1500 rpm to evaluate the performance of a engine with low heat rejection (LHR) combustion chamber. It consisted of an air gap (3 mm) insulated piston with superni (an alloy of nickel) crown and an air gap (3 mm) insulated liner with superni insert and ceramic coated cylinder head fuelled with different operating conditions (normal temperature and preheated temperature) of waste fried vegetable oil and its biodiesel with varied injection timing and injector opening pressure. Engine with LHR combustion chamber with biodiesel showed improved performance over conventional engine (CE) at 27° bTDC and at optimum injection timing. Biodiesel showed improved performance over crude vegetable oil with engine with both versions of the combustion chamber. Preheated test fuels and increase of injection pressure showed reduction of pollution levels and marginally improved performance over normal test fuels.
Application of an Optimized SLW Model to Calculation of Non-Gray Radiation Heat Transfer in a Furnace
Authors: Darbandi Masoud , Abrar Bagher , Schneider Gerry E.
Published: March 2016

The spectral line based weighted sum of gray gases (SLW) model is considered as an advanced model, which can solve the radiative transfer equation (RTE) in non-gray participating media by dividing the absorption cross section spectrum into a limited number of intervals. Each interval is then treated as a gray gas medium, in which the attributed RTE should be solved separately. Therefore, the SLW model would be computationally more efficient than the other non-gray participating media solvers because it is faced with a small number of RTE solutions. In this work, we present a novel optimized SLW model and applied it to radiation heat transfer calculation in a model furnace. The current optimized SLW model with only 3 gray gases can provide accuracy close to the line-by-line (LBL) method. This is while the classic nonoptimized SLW model cannot provide the same level of accuracy imposing only 3 gray gases. Therefore, we strongly recommend the optimized SLW model to calculate the radiation heat transfer in non-gray combustion gas mixtures.
Recorded Responses of a Light Truck With Rapid Left Front Air-Out of Super Oversized Mud Tires
Authors: Arndt Mark W.
Published: March 2016

A closed-loop test of a 1974 Ford F-150 4WD truck equipped with super oversized off-road mud tires was conducted to demonstrate that steering was possible after a left front rapid air-out event. A rim was built with six remotely deployable orifices that activated simultaneously and caused the air pressure to decrease below 2.5 psi in less than one second. The truck was configured in OEM condition except for the tires and rims. The tires were 42–14X16 mounted to 8X16 rims with zero offset. The tires that were originally sold with the vehicle were probably 8.75–16.5. Three tests at increasing speed of 35 mph, 45 mph, and 55 mph were conducted on a large, remote, and closed parking lot in a two-lane travel way marked with surface paint. The truck, while monitored with a standard suite of instruments and video, was brought to speed in a straight-line. At a predetermined point, and while maintaining a straight path, the throttle was dropped and the left front tire air-out was remotely triggered. The driver, aware of the test conditions and with the benefit of experience, was instructed to steer the truck to maintain its position within the simulated traffic lanes. The truck was equipped with a four-speed manual transmission which remained in fourth gear throughout the response phase of the test. The clutch was depressed and brakes applied only after steering control had corrected the vehicle’s leftward motion. The post air-out path of the truck evidenced by printing from the left front tire in each test was measured, photographed and plotted. The truck never left the simulated roadway travel lanes, which represented one direction of a typical four-lane California state highway. The test data was recorded at 200 samples per second and was post-processed with a 6 HZ, 12-pole, phaseless digital filter. Test results were plotted and presented. The test results are of interest because they are a demonstration of the concept that even under extreme conditions, if a test driver knows what is going to happen and knows what to do, a controlled vehicle motion is the likely outcome. In the tests, as the driver gained experience and the speed increased, lateral motion decreased. These findings are consistent with conclusions in a NHTSA tread separation study including, “when drivers had prior knowledge of the imminent tread separation, they were significantly less likely to sustain loss of vehicle control following the tread separation.” And, “findings from test track studies in which test drivers were aware of an imminent tread separation may underestimate the extent to which tread separation occurring in the real world leads to instability and loss of vehicle control.”
Combined Electrohydrodynamic Conduction Pumping and Dielectrophoresis for Enhancement of Liquid Film Flow Boiling
Authors: Patel Viral K. , Seyed-Yagoobi Jamal
Published: March 2016

The research in this paper extends previous liquid film flow boiling studies by including the effect of an additional electrohydrodynamic (EHD) force, namely the dielectrophoretic (DEP) force. Rather than using only EHD conduction pumping of the liquid film to electro-wet the heater surface, a localized non-uniform electric field above the heater surface is also used to generate a dielectrophoretic force for improved vapor bubble extraction during the nucleate boiling regime. The effect of liquid film height and applied potential are studied as a function of heater superheat and heat flux. The study considers the sole and combined effect of DEP with EHD conduction pumping. A brief analytical study is also used to estimate the expected dielectrophoretic force magnitude and explain the results. All of the above studies are also used to quantify the enhancement in heat transfer that can be achieved when heat transport systems are driven or augmented by these electrohydrodynamic phenomena. The results show remarkable enhancement of up to 1217% in heat flux and boiling heat transfer coefficient for a given superheat when both mechanisms are used simultaneously. The experimental data are important for applications in thermal management in terrestrial and micro-gravity conditions.
Macro-Micro Dual-Drive Stages Based on Dual Switching Condition and Local Closed Loop
Authors: Fang Jiwen , Long Zhili , Zhang Lufan
Published: March 2016

This paper presents macro-micro dual-drive stages using the hybrid actuators composed of voice coil motor (VCM) and piezoelectric actuator (PZT actuator). The macro stage driven by voice coil motor can achieve large travel range and coarse positioning. The micro stage with an embedded flexure hinges mechanism, actuated by the PZT actuator, can realize short range but high precision positioning. To gain precise performance, the dynamic modes of macro stage and micro stage are equivalent to mass-damping-spring system in this research. According to theoretical analysis, the output displacement of micro stage is proportional to the extension of the PZT Actuator. The linear relationship will be used to the motion control of micro stage. To realize perfect performance, the variable gain PID controller is designed to control the macro stage. In order to prevent saturation and damage of PZT actuator, dual switching control, positioning error threshold and small vibration displacement, are applied to the switching control. Beyond the micro stage range, the micro stage must be kept in its equilibrium position while the VCM instead reaches a long travel. The PZT actuator controller is used to compensate for position error after switching control. When the error is less than a set thres hold value, the error signal is added into the micro control loop. So the macro-micro dual-drive stages are working together to reduce the positioning error. The relationship between PZT actuator of closed loop and input voltage is linear by theoretical analysis and experiment test. So the micro stage uses an open servo loop structure, but the PZT actuator is controlled with PI controller in local closed loop in order to eliminate the nonlinear of PZT. The experimental system used in this study is single-axis dual-driving stages. Turbo PMAC PCI-Lite is the core of the whole system and executes PLC programs with motion programs. Experiments show that the steady state error of dual-drive stage is nano level. The steady state error of dual-drive stage can be improved. So dual-drive stages can increase the positioning accuracy of the whole system and the performance is superior to the single VCM stage.
Periodical Feature Extraction and Fault Diagnosis for Gearbox Using Local Cepstrum Technology
Authors: Li B. , Zhang X. N.
Published: March 2016

Results of numerous studies and experiments show that cepstrum analysis has the ability of simplifying the equally spaced sideband feature in the spectrum and highlights the signal components of defects. However, for most cases of early gear failure, the periodic phenomenon is always buried in strong background noises and the interference of the rotating frequency with its harmonics. Moreover, the features would be further weakened by the average effect of Fourier transform after cepstrum processing. In this paper, an improved cepstrum method named local cepstrum is proposed. The detection principle of local cepstrum is mainly based on the part of spectrum information to enhance the capability of extracting periodical features of detected signals. Besides, the autocorrelation and extended Shannon Entropy Function are also involved enhancing the periodic impulsive features. In the end, only several distinct lines with larger magnitudes would be left in the local cepstrum, which is very effective for gear fault detection and identification. Both simulation and experimental analysis show that the proposed method, which is more sensitive to the gear failure compared with conventional cepstrum analysis, could partially eliminate the interference of background noise and extract the periodical features of premature failure signals effectively.
Influence of Ethanol as a Carburizing Agent on Carbon Surface Concentration and Microstructure of DIN 17NiCrMo7 Steel Gears
Authors: Catalão Rogério , Khayyam Ribas Omar , Carneiro José Rubens G. , Freitas Érico , Vilela Costa Larissa , Brito Pedro Paiva
Published: March 2016

In the present work, the addition of ethanol to endothermic gas during the carburizing process of DIN 17NiCrMo7 steel gears was investigated with the objective of determining the impact on carbon surface concentration and microstructure. The materials were carburized at 870°C and 930°C, oil quenched, tempered and subsequently shot peened. Carburizing was carried out in a continuous industrial furnace for a total of 280 min. After quenching and tempering, the in-depth carbon concentrations were determined through quantitative chemical analysis and the resulting profiles were modeled in order to obtain carbon diffusivity constants. The amount of retained austenite and austenite grain size, determined by X-ray diffraction and optical microscopy, were found to increase with carburizing temperature. Residual stress profiles were also determined by X-ray diffraction before and after the shot-peening process. The microstructure of the specimens was further investigated by transmission electron microscopy, which revealed the presence of BCC martensite before and after shot-peening. The enrichment of the endothermic gas carrier with ethanol could be shown to be a viable option, allowing for surface concentrations of up to 0.8%C.
Stress Analysis of Bone Scaffold Designed for Segmental Bone Defects
Authors: Slaoui Idriss , Stephenson Makeda K. , Abdul Rauf Huma , Dow Douglas E. , Shady Sally S.
Published: March 2016

Segmental bone defects result in isolated bone fragments. These defects may be caused by trauma or disease and are a leading cause for orthopedic surgery. Segmental defects pose a challenge as they contain gaps between the ends of bones, which are too large for the regenerating tissue to naturally bridge and repair. A widely used clinical approach to repair such defects is the use of autografts that provide the essential bone growth features. However, autografts generate a secondary deficit in the region from which the graft was harvested. This grafting procedure may result in other complications, such as infections, inflammation, scarring, and bleeding. Synthetic bone scaffolding has been explored as a viable method of helping the body repair segmental bone defects. While synthetic bone scaffolding is a promising approach in orthopedic treatments, limitations exist. Bone is a complex organ with many cell types, emergent, anisotropic, mechanical properties and molecular interactions. Studies have shown that the inner geometries, such as pore size, play an integral role in bone regeneration, cell proliferation, differentiation and recovery. An architecturally-based approach in the design and fabrication of the scaffold may support the differentiation of complex bone tissues.

This study developed and tested scaffold designs having different pore size and beam thickness. The designs were developed and simulated for compression and tension in SolidWorks. A hexagonal unit cell was the basis for scaffold design. In one experimental trial (Group 1), the offset of the layers was varied. In another experimental trial (Group 2), the ratio between pore size and beam thickness was varied while using the optimal offset from the former trial. The material for simulation was poly-L-lactic (PLA) acid.

In the analysis of the simulation results, the optimal layer offset configuration of 100%,50% in the positive x-y direction showed the lowest stress distribution for both compression and tensile simulations compared to the other offset configurations analyzed. In the second trial of Group 2 models, two models with pore size to beam thickness ratios (7:1 and 8:1) demonstrated low stress distribution under the simulated physiological environments. These results suggest that both models can potentially have different applications in the repair of segmental bone defects.
On Numerical Simulation of Fuel Mixed With Steam or Air to Investigate Soot and Other Emissions
Authors: Patki Ajit , Li Xianchang , Chen Daniel , Lou Helen , Damodara Vijaya
Published: March 2016

Soot emissions (PM 2.5) as well as CO and NOx from industrial flares and other industrial processes or sources pose a substantial risk to human being health and the environment, and now are subject to new and tougher EPA regulations. Flaring is used widely used in many industries to dispose unwanted combustion gases by burning them as a flame. However, flaring produces significant amount of particulate matter in the form of soot, along with other harmful gas emissions. Although many experimental and numerical studies have previously been done on flames burning in a controlled condition, relatively few studies have been conducted with fuel-steam mixture. In practice, air and steam are commonly used to assist the flaring processes — control the smoke and the combustion efficiency. This study aims to investigate soot, CO and NOx emissions of turbulent diffusion methane and propane flame mixed with air or superheated steam. To study such effect numerically, the computational fluid dynamics software ANSYS Fluent 14.5 is used with non-premixed probability density function (PDF) model. The laminar flamelet is generated with automated grid refinement. For the soot generation, the Moss-Brookes soot model with Lee sub-model is considered. The combustion mechanism is developed by the authors’ research group from the combined GRI and USC mechanisms. Two types of fuel, methane and propane, are used. The amount of super-heated steam varied from four percent to twenty percent (4%, 8 %, 12%, 16%, and 20%), and the behavior of the flame is analyzed. For the baseline case, the jet has a diameter of 50.8 mm or 2 inches, and the jet velocity is kept to 1.0 m/s. A co-flow air is supplied at a velocity of 0.2 m/s. The temperature distribution of methane and propane are compared with different contents of steam or air assists. The NOx, Soot and CO yields (kg/kg) varying with steam or air percentages are also presented. The results indicate that the soot yield is dependent on fuel type strongly and the percentage of steam or air affects the soot yield differently as the fuel type varies.