bluuebunny/crossref_metadata_2025_split huggingface dataset:
Real-Time 3D Model Reconstruction and Interaction Using Kinect for a Game-Based Virtual Laboratory
Authors: Zhang Zhou , Zhang Mingshao , Chang Yizhe , Aziz El-Sayed , Esche Sven K. , Chassapis Constantin 
Published: April 2014

Over the last few years, academic institutions have started to explore the potential of using computer game engines for developing virtual laboratory environments. Recent studies have shown that developing a realistic visualization of a physical laboratory space poses a number of challenges. A significant number of modifications are required for adding customized interactions that are not built into the game engine itself. For example, a major challenge in creating a realistic virtual environment using a computer game engine is the process of preparing and converting custom models for integration into the environment, which is too complicated to be performed by untrained users.
This paper describes the usage of the Microsoft Kinect for rapidly creating a 3D model of an object for implementation in a virtual environment by retrieving the object’s depth and RGB information. A laboratory experiment was selected to demonstrate how real experimental components are reconstructed and embedded into a game-based virtual laboratory by using the Kinect. The users are then able to interact with the experimental components. This paper presents both the technical details of the implementation and some initial results of the system validation.
Simplified Modeling Technique for Damping Materials on Light Structures: Experimental Analysis and Numerical Tuning
Authors: Splendi Luca , D’Agostino Luca , Baldini Andrea , Castignani Luca , Pellicano Francesco , Pinelli Marco 
Published: April 2014

Specific polymeric and asphaltic materials are widely used for NVH automotive applications. If patches of such materials are properly collocated on vehicle’s panels, they are able to improve significantly noise and vibration performance by modulating damping and stiffness.
This work presents a methodology for tuning a FE composite model, using optimization techniques to improve the correlation with the experimental modal tests performed.
In particular, plain and ribbed aluminum plates have been considered for several covering ratios of three damping materials.
The correlation between numerical and experimental data is achieved by monitoring dynamic parameters such as natural frequencies, mode shapes, and frequency response functions (FRFs). The optimization strategy consists of two steps and makes use of evolutionary and gradient-based algorithms. LMS Virtual.Lab® is used in this part of the work as an environment for correlation and optimization.
In order to verify the reliability of the correlation, modal tests are performed on a particular vehicle’s panel.
Optimization of the Thermodynamics Cycles of Generation IV Gas-Cooled Fast Reactors
Authors: Polanský Jiří , Gášpár Roman 
Published: April 2014

This paper deals with the thermo-hydraulic properties of Generation IV Gas Cooled Fast Reactors. The paper is focused on the comparison of direct and indirect thermodynamic cycles of helium cooled reactors from a thermodynamic point of view. The calculation includes pressure losses at all major parts of the equipment — reactor, heat exchangers, pipe lines, etc. The compressor and the gas turbine efficiencies are included in calculation as well. The working fluid used in the primary circuit is helium. In the secondary circuit a mixture of helium and nitrogen is used. The cycle characteristic point and efficiency calculation reflects mixture properties of the real gas — especially for N2.
Calculations point out the influence of the mixture composition on the basic structural parameters of the turbines, compressors and heat exchangers. Thermodynamic cycle efficiency, specific heat input/output, heat flux and cycle work will be presented as characteristic parameters.
Wilsak-Thodos Equation of State for Refrigerants
Authors: Rogdakis E. D. , Koronaki I. P. , Gorgoraptis E. 
Published: April 2014

In recent years different equations of state for environmentally friendly refrigerants have been developed from different sources of experimental data which, in many cases, use a very large number of auxiliary functions and coefficients. A rather interesting equation that has not been recollected lately, proposed by Wilsak and Thodos in 1985, appears to have a convenient form for effective and significantly accurate calculations of the thermophysical properties of substances.
Wilsak-Thodos equation of state presents a relatively simple form as it correlates experimental data with the corresponding ones at saturation and contains only three density dependent functions. For this reason, this study attempts to identify the coefficients of the equation approximating accurately the experimental data and attributing in an integrated manner with auxiliary equations for some of the most common of the environmental friendly refrigerants.
Flow Structures and Losses in the Exhaust Port of an Internal Combustion Engine
Authors: Wang Yue , Semlitsch Bernhard , Mihaescu Mihai , Fuchs Laszlo 
Published: April 2014

A numerical study of the flow in the exhaust port geometry of a Scania heavy-duty Diesel engine is carried out mainly by using the Large Eddy Simulation (LES) approach. Unsteady Reynolds Averaged Navier-Stokes (URANS) simulation results are included for comparison purposes. The calculations are performed with fixed valve and stationary boundary conditions for which experimental data are available. The simulations include a verification study of the solver using different grid resolutions and different valve lift states. The calculated numerical data are compared to existent measured pressure loss data. The results show that even global parameters like total pressure losses are predicted better by LES than by URANS. The complex three-dimensional flow structures generated in the flow field are qualitatively assessed through visualization and analyzed by statistical means.
The near valve region is a major source of losses. Due to the presence of the valve, an annular, jet-like flow structure is formed where the high-velocity flow follows the valve stem into the port. Flow separation occurs immediately downstream of the valve seat on the walls of the port and also on the surface of the valve body. Strong longitudinal, non-stationary secondary flow structures (i.e. in the plane normal to the main flow direction) are observed in the exhaust manifold. Such structures can degrade the efficiency of a possible turbine of a turbocharger located downstream on the exhaust manifold.
An Experimental Study of the Effect of Drag Reducing Additive on the Structure of Turbulence in Concentric Annular Pipe Flow Using Particle Image Velocimetry Technique
Authors: Rodriguez Corredor Fabio Ernesto , Bizhani Majid , Kuru Ergun 
Published: April 2014

The effect of drag reducing additive on the structure of turbulence in concentric annular pipe flow was investigated using Particle Image Velocimetry (PIV) technique. Experiments were conducted using a 9m long horizontal flow loop with concentric annular geometry (inner to outer pipe radius ratio = 0.4). The drag reducing additive was a commercially available partially hydrolyzed polyacrylamide (PHPA). The experiments were conducted using 0.1% V/V polymer concentration, giving a drag reduction of 26% at a solvent Reynolds number equal to 56400.
Near wall local fluctuating velocity values were determined by analysing the PIV data. The root mean square (RMS) values of radial velocity fluctuations showed a significant decrease with the use of drag reducing additive. The RMS values of axial velocity fluctuations near the wall (Y+<10) were similar for both water and polymer fluid flow; though, higher peaks were obtained during the polymer fluid flow.
As compared to water flow, a strong reduction in vorticity was observed during polymer fluid flow. The degree of vorticity reduction on the inner wall was higher than that of the outer wall.
Results of the viscous dissipation and the shear production terms in the kinetic energy budget showed that less energy was produced and dissipated by the route of turbulence when using polymer fluid.
Flexural Modulus of Lasersintered PA 2200
Authors: Coy Johannes A. , Kuball Clara-Maria , Roppenecker Daniel B. , Lueth Tim C. 
Published: April 2014

With the evolving of rapid manufacturing methods, new fields of application become feasible. Selective Laser Sintering (SLS), an additive process, allows the production of medical devices made out of PA 2200, a biocompatible plastic powder. Due to the fast production cycle, medical robots or devices can be highly customised. However, those new production methods force the engineer to design robots and mechanisms adapted for this process. In particular the use of compliant structures is necessary if small mechanisms are to be created.
Creating laparoscopic grippers out of flexible hinges revealed that there are properties unknown for the particular material used. Lasersintered PA 2200 parts seem to have a flexural modulus, which varies with their thickness and build orientation during the production process. This paper investigates those phenomenons with three-point loading tests. A dependency could be found and has been characterised for five orientations allowing the engineer to estimate the flexural modulus of lasersintered PA 2200 parts according to their thickness.
Errors and Uncertainties: What Hath the GUM Wrought?
Authors: Emery A. F. , Vosk T. 
Published: April 2014

Traditional error analysis to estimate the uncertainties in experimental measurements and predictions has given way during the last two decades to uncertainty analysis. The current methodology is described in the GUM (Guide to the Expression of Uncertainty in Measurement) issued by ISO. The reasoning behind the change was the recognition that one could never know the true value of a measurement and thus the error could not be determined.
As promulgated, the uncertainties are represented in statistical terms based upon sampling (classical statistics) and upon subjective reasoning (Bayesian). The approach combines these uncertainties in the usual error analysis approach of summing the variances (now labeled the ‘Law of Propagation of Uncertainties’) and then using the student-t distribution to attach some meaning to the result.
The correct procedure is to apply the Bayesian approach throughout, but many investigators have heard only that Bayesian inference is computationally expensive and question the idea of subjective probability and resort to using the Law of Propagation of Uncertainties.
This short note treats the common problem of the uncertainty of a measurement using a calibrated device. It compares the two methods, reminding the reader of what the GUM calls for and assumes, and showing that with our current computing power there is no good reason to avoid Bayesian inference to provide more exact and informative understandings of measurement uncertainties.
Steepest Entropy Ascent Models of the Boltzmann Equation: Comparisons With Hard-Sphere Dynamics and Relaxation-Time Models for Homogeneous Relaxation From Highly Non-Equilibrium States
Authors: Beretta Gian Paolo , Hadjiconstantinou Nicolas G. 
Published: April 2014

We present a family of steepest entropy ascent (SEA) models of the Boltzmann equation. The models preserve the usual collision invariants (mass, momentum, energy), as well as the non-negativity of the phase-space distribution, and have a strong built-in thermodynamic consistency, i.e., they entail a general H-theorem valid even very far from equilibrium. This family of models features a molecular-speed-dependent collision frequency; each variant can be shown to approach a corresponding BGK model with the same variable collision frequency in the limit of small deviation from equilibrium. This includes power-law dependence on the molecular speed for which the BGK model is known to have a Prandtl number that can be adjusted via the power-law exponent.
We compare numerical solutions of the constant and velocity-dependent collision frequency variants of the SEA model with the standard relaxation-time model and a Monte Carlo simulation of the original Boltzmann collision operator for hard spheres for homogeneous relaxation from near-equilibrium and highly non-equilibrium states. Good agreement is found between all models in the near-equilibrium regime. However, for initial states that are far from equilibrium, large differences are found; this suggests that the maximum entropy production statistical ansatz is not equivalent to Boltzmann collisional dynamics and needs to be modified or augmented via additional constraints or structure.
Feasibility Analysis for a Tidal Energy Pilot Site in the Gulf of California
Authors: Tapia Olivas Juan Carlos , Ramírez Campbell Hector Enrique , Gil Samaniego Ramos Margarita 
Published: April 2014

Baja California is located in the northwestern region of Mexico and is a peninsula that borders the west by the Pacific coast and on the east by the Gulf of California, with 1,280 km of coastal area of which 560 km belong to the Gulf California and the rest to the Pacific Ocean. It is privileged with renewable energy resources and already has 720 MW of geothermal, 10 MW of Wind and 5 MW of Solar that presently are under construction. With the growing demand for electricity especially in the summer period, the use of tidal power is an opportunity to use a resource of this type in the coastal towns.
This paper presents an analysis which assesses the bays of Santa Maria, San Luis Gonzaga, Los Angeles, El Pescador, El Soldado, Las Animas and San Rafael, as sites with ideal features for the implementation of tidal power generation technology. The analysis, weighed the constructive feasibility, site bathymetry, environmental impact to the area, roads, generation capacity and population of nearby sites. The Port of San Felipe with a population of 16,945 inhabitants, is located in the Gulf of California, having a population growth rate of 2.3 % year, and has 4,579 users in the residential sector who demand 27,483 MWh annually, being the months of July to August when they consume 60% of the year’s energy.
It was calculated that the maximum estimated power potential was in the Bay of San Rafael with 14 MW, and the minimum power value was obtained for Bay of Soldado with 1.3 MW. However the Bay of Santa Maria with a maximum power of 2.5 MW is considered the most viable site for the development of a tidal project according to the weighing used primarily, due to its proximity to the Port of San Felipe.
One of the main restrictions for the development of tidal energy on these sites is the high environmental impact that could occur in these areas. Due to the that as biophysical characteristics and coastal geomorphology of these bays, these sites are very fragile in terms of negative impacts that could be generated by changes in ocean currents due to the construction of infrastructure for tidal generation.
Numerical Study of Transient Multiphase Slug Flow Through a Tube at High Velocity
Authors: Adam Carlton , Hadim Hamid 
Published: April 2014

A transient, two-dimensional computational fluid dynamics model is used to simulate the flow of a liquid slug through a pipe at high velocities. The slug is driven by a gas which enters the system at a constant pressure of 10 MPa. The gas accelerates the slug from rest through a distance of about 45 cm, after which the slug discharges into the open atmosphere. The interface between the two phases is initially uniform and flat, however as the flow develops, significant interphase mixing and deformation of the interface occurs.
The simulation is ultimately used to predict the velocity and dispersion pattern of the liquid slug upon discharge into the atmosphere. The gas pressure and dispersion pattern over time are compared to experimental data collected via high-speed cinematography and piezoelectric pressure gauges. The numerical model predicts a slug exit velocity of 108 m/s which agrees reasonably well with empirical measurements. However, the numerical model fails to accurately predict the structure of the dispersion pattern of the exiting liquid, specifically in terms of the amount of mixing between the liquid and gas phases. To address these discrepancies between the model and the empirical data, a follow-on effort will be performed in an attempt to better capture the formation of the large expansion plume seen in the high-speed video. Specifically, phase changes in the liquid and gas will be addressed in the follow-on effort, as will turbulence effects on mixing at small scales.
The Effects of Surfactant on Simplex Nozzle Spray Behavior and its Comparison to Liquid Fuels
Authors: Davanlou Ashkan , Lee Joshua , Basu Saptarshi , Kumar Ranganathan 
Published: April 2014

Pressure-swirl nozzles (simplex nozzles) are used in various field applications such as aero-engines, power generation, spray painting and agricultural irrigation. For this particular nozzle, research in the past decade has dealt with the development of numerical models for predicting droplet distribution profiles. Although these results have been valuable, the experimental results have been contradictory, therefore fundamental understanding of the influence of properties in nozzle is important. This paper experimentally investigates the effect of surfactants on breakup and coalescence. Since most of the fuels and biofuels have low surface tension compared to water, a comparative analysis between a surfactant solution and a liquid fuel is imperative. For this experimental study, a simplex nozzle characterized as flow number 0.4 will be utilized. The injection pressures will range from 0.3–4Mpa while altering the surface tension from 72 to 28mN/m. By applying Phase Doppler Particle Anemometry (PDPA) which is a non-intrusive laser diagnostic technique, the differences in spray characteristics due to spray surface tension can be highlighted. The average droplet diameter decreases for a low surface tension fluid in the axial direction in comparison to pure water. The average velocity of droplets is surprisingly lower in the same spray zone. Measurements made in the radial direction show no significant changes, but at the locations close to the nozzle, water droplets have larger diameter and velocity. The results indicate the breakup and coalescence regimes have been altered when surface tension is lowered. A decrease in surface tension alters the breakup length while increasing the spray angle. Moreover, higher injection pressure shortens the breakup length and decrease in overall diameter of the droplets.
By performing this experimental study the fundamentals of spray dynamics, such as spray formation, liquid breakup length, and droplet breakup regimes can be observed as a function of surface tension and how a surrogate fuel compares with a real fuel for experimental purposes. This knowledge potentially will lead to designing a better atomizer or new biofuels.
Thermal-Economic Modeling of a Micro-CHP Unit Based on a Stirling Engine
Authors: Ferreira Ana C. , Teixeira Senhorinha , Ferreira Christophe , Teixeira José , Nunes Manuel L. , Martins Luís B. 
Published: April 2014

The last decade has witnessed a growing interest in the use of Stirling engine cogeneration systems for residential applications, due to their prospect for high efficiency, good performance at partial load, fuel flexibility, including the possible use of renewables, low emissions, vibration and noise levels. Stirling engines have sealed operating chambers, low wear and, as a consequence, low operating costs. In the European building sector, micro-cogeneration power plants are being designed to fulfill the heating requirements of the building and, additionally, generate electricity for internal consumption or for feeding into the local grid.
Thermal-economic evaluation represents an effective tool to optimize a power plant with this type of technology. The mathematical formulation includes a set of equations able to describe and simulate the physical system, as well as a set of equations that define the cost of each plant component.
This paper presents a numerical study faithfully simulating the real conditions of a micro-CHP unit based on an alpha type Stirling Engine. The simulations were performed through a MatLab® code that assesses the thermodynamic efficiency, including heat transfer limitations and pumping losses throughout the system.
Results showed that heat-transfer limitations strongly affect cycle efficiency, particularly in the regenerator case. The pumping losses are less important when hydrogen or helium are used.
Thermophysical Properties of AS4/3501-6 Carbon-Epoxy Composite
Authors: Vital Amber , Doleman Bradley , Saad Messiha 
Published: April 2014

As today’s technology continues to develop at a rate that was once unimaginable, the demand for new materials that will outperform traditional materials also increases dramatically. To meet these challenges, monolithic materials are being combined to develop new unique materials called composites. Thermophysical properties of composite materials such as thermal conductivity, diffusivity, specific heat, and thermal expansion are very important in engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells. Thermal conductivity is the property that determines the working temperature levels of a material and plays a critical role in the performance of materials in high temperature applications. This parameter is important in problems involving heat transfer and thermal structures.
The objective of this paper is to develop a thermal properties database for the carbon-epoxy AS4/3501-6 composite. The AS4 carbon fiber used is a unidirectional continuous PAN based fiber, and the 3501-6 epoxy resin is amine cured and provides low shrinkage during the curing process while maintain resistance to chemicals and solvents. The thermophysical properties of the AS4 composite have been investigated using experimental methods. The flash method was used to measure the thermal diffusivity of the composite based on the American Society for Testing and Materials standard, ASTM E1461. In addition, the Differential Scanning Calorimeter was used in accordance with the ASTM E1269 standard to measure the specific heat. The measured thermal diffusivity, specific heat, and density were used to compute the thermal conductivity, thus adding to the currently insufficient database for composite materials and foams.