bluuebunny/crossref_metadata_2025_split huggingface dataset:
Confirmation of the Natural Yawing Frequency of Large Sized Vehicle: Distinguishing the Vehicle System From the Driver-Vehicle System
Authors: Momiyama Fujio , Sasaki Takashi , Nagae Hiroyasu 
Published: November 2021

Abstract
The low yawing natural frequency of vehicle system and/or the coupled natural frequency of driver-vehicle system is considered as a reason for vehicle fluctuation. In the case of passenger cars, it is well known that the yaw-gain-peak of vehicle system exists at 1–2 Hz and that of driver-vehicle system exists at 0.3–0.4Hz. In the case of large sized vehicle systems, I, Momiyama, reported in SAE No.892519 that the yaw-gain exists at 0.3–0.4 Hz. As this value is so close to the value of driver-vehicle system, sometimes the discussion regarding the vehicle dynamics of large sized vehicles seems to be confused. The purpose of this paper is to confirm the yawing behavior and to clarify the reason for the low yawing frequency of vehicle system. Firstly verification procedure and a 7DOF vehicle model considering the lateral and rotational motion of sprung mass, front/rear un-sprung mass and rotational motion of steering system are introduced. Secondly the lateral fluctuation running under fixed steering wheel is shown. We named this behavior “tottering”. Thirdly the yaw response test results by random steering input based upon ISO/TR8726 are shown. From the above testing and calculating analysis the existence of a low yaw-eigen value is confirmed. From the vector analysis of the low yaw-eigen value it is known the main factor of the low frequency is the low rigidity of steering with power steering system. The low rigidity is caused by the low spring constant of power steering servo-valve that has the dead zone at on-center.
A Comparison of the Relative Benefits of Active Front Steering and Active Rear Steering When Coordinated With Direct Yaw Moment Control
Authors: Selby M. A. , Manning W. J. , Brown M. D. , Crolla D. A. 
Published: November 2021

Abstract
This paper studies the benefits of coordinating stability and steerability controllers to reduce vehicle deceleration during limit handling situations. The stability controller, DYC, uses the vehicle brakes to apply a restoring moment when the vehicle sideslip angle and sideslip velocity exceed fixed bounds. This use of the brakes interferes with the longitudinal dynamics of the vehicle in a way that drivers find undesirable. Active front steering (AFS) and active rear steering(ARS) can be used to tune the vehicle handling balance in the low to mid-range lateral-acceleration regime. Earlier work has shown that the use of AFS can reduce the interference observed using DYC alone. The levels of improvement achievable by coordinating AFS and ARS with DYC are quantified using open loop handling simulations tests by predicting the deceleration of the vehicle in an extreme manoeuvre. The results from these simulations are compared to assess the relative benefits of AFS and ARS when coordinated with DYC. The computer simulations are based on a four-degree of freedom vehicle model incorporating longitudinal, lateral, yaw, roll, and load transfer effects.
Finite Element Modeling of Non-Orthogonal Loosely Woven Fabrics in Advanced Occupant Restraint Systems
Authors: Tanov Romil R. , Brueggert Marlin 
Published: November 2021

Abstract
The behavior of loosely woven fabrics differs significantly from other types of woven fabrics. Its unique characteristics have been successfully utilized for the correct operation of some recently developed occupant protection devices for the automotive and heavy machine and truck industry. However, this behavior cannot be efficiently modeled using the currently available material models within a finite element analysis scheme. Therefore, the aim of this work is to present the basics of a formulation of a material model for the analysis of loosely woven fabrics and its implementation in a general-purpose explicit finite element code. To assess the performance of the model, results from the simulation are presented and compared to real test data.
Racing Car Simulation and the Virtual Race Track
Authors: Siegler Blake , Crolla David 
Published: November 2021

Abstract
A number of handling models of a small high performance formula type racing car have been produced. These have been used to optimise the performance of the vehicle whilst under going simple manoeuvres and around a complete race track. Recently the vehicle was fitted with a data acquisition system and objective data was taken of the vehicle’s handling performance.
The paper details an investigation into the accuracy of two (a simple and more sophisticated) vehicle handling models in predicting the actual vehicle’s performance from the data collected by comparing measured and simulated results. The investigation studies the steady state and transient response of the vehicle up to the limit of the vehicle’s handling performance.
A description is also given of the use of the more sophisticated model in a virtual race track simulation where it is used as a development tool to tune the performance of future vehicles.
Optimal Engine Operations in Series Hybrid Electric Vehicles
Authors: Wang Wenping 
Published: November 2021

Abstract
Numerical optimal control techniques are employed to define the best engine operating strategies for series hybrid electric vehicles in this paper. On the basis of formulating the energy management as a linear minimum-fuel problem with linear input and state constraints, both linear programming (LP) and mixed integer linear programming (MILP) are applied to find the numerical solutions. In particular, the on-line computations of the resultant LP-based and MILP-based optimal controllers are reduced to simple linear function evaluations via using recursive linear program equivalents. Therefore, the resulting optimal engine control strategies are attractive for real-time control and optimization of fuel economy in hybrid vehicles. Simulation results of the proposed approach show improvement in fuel economy over the “Load Leveling” and “Load Following” engine operating modes.
Modeling of Continuous and Intermittent Gas Jet Impingement and Heat Transfer on a Solid Surface
Authors: Chaniotis A. K. , Poulikakos D. 
Published: November 2021

Abstract
The present work focuses on the effect of flow pulsation on the characteristics of the planar jet impingement normally on a heated surface. Specifically, the influence of frequency, amplitude and Reynolds number of the jet is examined, concerning the instantaneous and time average convective heat transfer. The simulations are conducted using a novel, improved Smooth Particle Hydrodynamics (SPH) methodology that is based on particle discretization of the governing compressible Navier-Stokes equations. The simulation of jet impingement focuses on the quantitative description of the flow field and the energy exchange between jet and surface. The strong aerodynamic and thermal interaction that exists between the gaseous jet and the impingement surface greatly enhances the local heat transfer in the stagnation and wall jet regions as well as the average heat transfer over the surface. This study is the first step toward modeling the same process but in the presence of chemical reactions and ablation between the gaseous jet and the plate.
Higher-Order Boundary Element Methods for Unsteady Convective Transport
Authors: Dargush G. F. , Grigoriev M. M. 
Published: November 2021

Abstract
Higher-order boundary element methods (BEM) are presented for time-dependent convective diffusion problems. The time-dependent convective diffusion free-space fundamental solutions originally proposed by Carslaw and Jaeger are used to obtain the boundary integral formulation. For the linear, quadratic and quartic time interpolation functions considered in this paper, a complete set of closed form time integrals for the one-dimensional formulation are developed. Boundary element method solutions are obtained for four problems of unsteady convection-diffusion, including shock wave propagation. It is shown that the BEM solutions are extremely accurate in contrast to finite-difference and finite-element methods. Moreover, no upwinding is needed for the boundary element methods, even for high Peclet number flows. Finally, the conventional BEM formulation is extended to a problem involving singular flux arising due to a sudden rise of temperature on the boundary. This infinite flux BEM formulation provides significantly more accurate numerical results than the conventional approach.
Slip-Flow Constant-Wall-Temperature Nusselt Number in Circular Tubes in the Presence of Axial Heat Conduction
Authors: Simek Olga , Hadjiconstantinou Nicolas G. 
Published: November 2021

Abstract
We present an investigation of slip-flow constant-wall-temperature convective heat transfer in circular tubes under hydrodynamically and thermally fully developed conditions. Our analysis includes the contribution of axial heat conduction (finite Peclet number) which is important in small scale flows, and has not been included in previous investigations of slip-flow heat transfer. The Nusselt number is found to decrease with increasing Knudsen number for all Peclet numbers in the fully accommodating case, as expected. The effect of axial heat conduction is found to be most important at Kn = 0, and results in an increase in the Nusselt number of the order of 15%; as Kn increases, the effect of axial heat conduction decreases.
Transition to Weak Turbulence, Chaos and Hysteresis in Natural Convection
Authors: Vadasz Peter 
Published: November 2021

Abstract
The fundamental understanding of the transition from laminar to turbulent convection is far from being conclusive. While major efforts are under way, there is still a significant challenge in front of the scientist and engineer to uncover the complex behavior linked to this transition. In isothermal shear flows the time dependent and three dimensional form of turbulence is well established experimentally and numerically. It is caused by the non-linear terms in the isothermal Navier-Stokes equations. Weak turbulence is linked to the problem of natural convection where an additional non-linear interaction appears as a result of the coupling between the equations governing the fluid flow and the energy equation. The latter can typically cause a transition to a non-steady and non-periodic regime (referred to as weak turbulent) at much lower values of the parameter controlling the flow, when compared to the corresponding isothermal system.
Controlled Contact Angle and Droplet Evaporation Using Photo-Induced Hydrophilic Surface
Authors: Takata Y. , Hidaka S. , Nakamura T. , Yamamoto H. , Masuda M. , Ito T. 
Published: November 2021

Abstract
Titanium Dioxide, TiO2, is one of the photocatalysts that has a very unique characteristic. The surface coated with TiO2 exhibits extremely high affinity for water by exposing the surface to ultraviolet ray and the contact angle decreases nearly to zero. On the contrary, the contact angle increases when the surface is shielded from ultraviolet ray. We have developed two types of TiO2 surface by sputtering process. One is the copper surface with TiO2 layer and the other is with TiO2 and SiO2 layer. The contact angle of the former varies between 30–82° and the latter varies between 4–13°. We applied these surfaces to control the contact angles with the other thermal properties of the surface being constant. Experiment of droplet evaporation has been performed to manifest the effect of contact angle on the evaporation curves. It is found that the wetting limit temperature increases as the contact angle decreases to 13°, but it decreases again as the contact angle decreases to 4°.
Design and Fabrication of an Optomechanical Uncooled Infrared Imaging System
Authors: Zhao Y. , Yamaguchi J. , Choi J. , Morales S. , Horowitz R. , Majumdar A. , Norton P. , Kitching J. , Li H. , Athavale M. 
Published: November 2021

Abstract
This paper discusses the design of an uncooled optomechanical infrared imaging system. A micromachined micro-cantilever array serves as an uncooled infrared imaging sensor known as focal-plane array (FPA). When exposed to an infrared source, the absorption of the incoming radiation energy by the cantilever will raise its temperature. Due to the thermal expansion mismatch of the two materials, the temperature rise will induce bending of the cantilever. The pixel design based on considerations of thermal, mechanical, and optical properties, and also compatibility with micro-fabrication process has been described in detail. By detecting the deformation of the cantilever optically using a laser interfometry system, the thermal information of the infrared source can be extracted. The paper describes the microfabrication process of the FPA, and a primary test on the temperature response of the pixel shows reasonable agreement with the theoretical analysis.
Photonic and Radiative Properties of Bubble Arrays
Authors: Miyazaki Koji , Yang Bao , Narayanaswamy Arvind , Chen Gang 
Published: November 2021

Abstract
In this paper we explore the photonic and radiative properties of regular bubble arrays. The photonic band structure and transmissivity, reflectivity and absorptivity of the arrays are calculated numerically. In particular we investigate the effects of packing density and lattice constant on the absorptivity by the numerical simulation.
A Pore Network Model for Drying Processes in Porous Media
Authors: Yiotis A. G. , Stubos A. K. , Boudouvis A. G. , Yortsos Y. C. 
Published: November 2021

Abstract
A pore network model for the drying of capillary porous media is presented in this work. The model accounts for various processes at the pore scale including evaporation of a volatile liquid, mass transfer of the vapors by advection and diffusion in the gas phase and viscous flow in the liquid and gas phases. Both viscous and capillary forces at the liquid menisci in pore throats are also modeled. We consider isothermal drying in a rectilinear horizontal geometry, with no flow conditions in all but one boundary, at which a purge gas is injected at a constant rate. Drying rates, phase distribution and concentration patterns are reported as a function of time and the gas flow rate. We also refer to the evolution of trapped liquid clusters.
An Experimental Investigation of Reflux Condensation Phenomena in Multiple U-Tubes With and Without Noncondensible Gas
Authors: Chun Moon-Hyun , Lee Kyung-Won , Chu In-Cheol 
Published: November 2021

Abstract
A series of experiments were performed to investigate the thermal-hydraulic phenomena inside U-tubes in a reflux condensation mode. A total of 512 data for local condensation heat transfer coefficients (108 for pure steam flow and 404 for steam-air flow conditions, respectively) have been obtained for various inlet flow rates of steam and air under atmospheric condition. A new correlation, which includes the effects of flow rates of steam and noncondensible gases (air) on the heat transfer coefficient and is applicable to the reflux condensation mode, has been developed using the concept of degradation factor based on the steam-air experimental results. In addition, the effects of multiple U-tubes with different lengths (i.e., two-long and two-short U-tubes) and noncondensible gases on the onset of flooding during a reflux condensation have been examined.
Cooling Characteristics of Two-Phase Impinging Jets
Authors: Kakumoto Taiki , Tomemori Hideki , Horiki Sachiyo , Osakabe Masahiro 
Published: November 2021

Abstract
Cooling of surfaces is often carried out in devices consisting of arrays of round nozzles, through which coolant impinges vertically upon the surfaces. To enhance the heat transfer coefficient and save the amount of coolant, two-phase jets were applied to the cooling of copper surface of 30mm in diameter. Experiments were conducted with using water and air at atmospheric pressure.
The heat transfer coefficient by single-phase water jets was well described with an empirical correlation. The experimental heat transfer coefficient increased with addition of air. When the volumetric air flow ratio β is less than 0.2, the heat transfer coefficient by air/water two-phase jets was larger than the prediction where the volumetric two-phase velocity and the physical properties of water were used in the empirical correlation for single phase heat transfer. However, the experimental data gradually decreased with increase of gas phase at β &gt; 0.2.
To study the enhancement and degradation mechanism of impinging two-phase heat transfer, the flow pattern in a capillary tube such as the nozzle tube and the impinging behavior on a transparent glass plate were observed with a high-speed video camera. When β was small, numerous air micro bubbles of very small diameter were impinging on the heat transfer surface. When β was large, impinging micro bubbles could not be observed. Gas and water phases intermittently impinged on the glass plate as the heat transfer surface. In the observed photograph, a hexagonal pattern resulting from interference among the adjusting two-phase jets could be recognized.
The enhancement of heat transfer at β &lt; 0.2 is considered to be due to the micro bubbles sweeping on the surface. The degradation at β &gt; 0.2 is mainly due to the lower thermal capability of gas-phase than that of liquid-phase. The gas-phase intermittently impinged on the surface and its heat transfer was relatively low.
Numerical Modeling of Aerosol Transport and Removal in Channels Using the Particle Tracking Method
Authors: Wu X. M. , Ghiaasiaan S. M. , Abdel-Khalik S. I. 
Published: November 2021

Abstract
Turbulent transport and deposition of microscopic particles in commonly-used large, and micro-channels were investigated. The objective was to examine the suitability of the Reynolds-averaged Navier-Stokes (RANS)-type turbulence models, along with a Monte-Carlo Lagrangian particle tracking method that accounts for the stochastic particle-turbulent eddy interactions, for the modeling of aerosol transport when a multitude of forces act on the particles.
The computer program KIVA-3 (Amsden et al., 1993) was modified and enhanced by adding several turbulence models, and including appropriate models for the effect of the following mechanisms on particle motion: drag, gravity, thermophoresis, Brownian dispersion, and shear-induced (Saffman) lift force. The effect of Brownian motion was modeled by including a random, white noise force term in the particle equation of motion. Parametric simulations were performed, leading to the following main observations. For the transport and deposition of microscopic particles, in addition to the turbulent dispersion, several other dispersion mechanisms were important. The k-ε and Reynolds-stress transport models provided similar predictions for sub-micron particles, but differed significantly for larger particles.
The model provided physically consistent results with correct trends in all the simulations. The methodology, however, appears to be expensive in terms of computations, and further work is needed for streamlining the numerical solution methods and physical models.
Transport Characteristics of a Multi-Species Slurry in a Horizontal Pipeline
Authors: Skudarnov P. V. , Kang H. J. , Lin C. X. , Ebadian M. A. , Gibbons P. W. , Erian F. F. , Rinker M. 
Published: November 2021

Abstract
In the course of the U.S. Department of Energy’s (DOE) tank waste retrieval, immobilization, and disposal activities, high-level waste transfer lines have the potential to become plugged. In response to DOE’s needs, Florida International University’s Hemispheric Center for Environmental Technology (FIU-HCET) is studying the mechanism and behavior of pipeline plugging to determine the pipeline operating conditions for safe slurry transport.
Transport behavior of multi-species slurry has been studied in a 1-in O.D. pipeline flow loop. The slurry was a five-species mixture of Fe2O3, Al2O3, MnO2, Ni2O3, and SiO2, which simulated actual waste at the Savannah River DOE site. The relationship between the pressure drop in the straight horizontal sections of the flow loop and the mean slurry flow velocity was determined for two solids volume concentrations of 5.2 and 7.8%. Critical deposition velocity was measured from visual observations. An existing empirical model that predicts the pressure gradient for a single-species slurry flow in a horizontal pipeline was used to describe the pressure drop data.
Air Ingress Analyses on a High Temperature Gas-Cooled Reactor
Authors: Oh Chang H. , Moore Richard L. , Merrill Brad J. , Petti David A. 
Published: November 2021

Abstract
A loss-of-coolant accident is one of the design-basis accidents for a high-temperature gas-cooled reactor (HTGR). Following the depressurization of helium in the core, if the accident is not mitigated, there exists the potential for air to enter the core through the break and oxidize the in-core graphite structure in the modular pebble bed reactor (MPBR). This paper presents the results of the graphite oxidation model developed as part of the Idaho National Engineering and Environmental Laboratory’s Directed Research and Development effort.
Although gas reactors have been developed in the past with limited success, the innovations of modularity and integrated state-of-art control systems coupled with improved fuel design and a pebble bed core make this design potentially very attractive from an economic and technical perspective. A schematic diagram of a reference design of the MPBR has been established at a major component level (INEEL & MIT, 1999). Steady-state and transient thermal hydraulics models will be produced with key parameters established for these conditions for all major components. Development of an integrated plant model to allow for transient analysis on a more sophisticated level is now being developed. In this paper, preliminary results of the hypothetical air ingress are presented. A graphite oxidation model was developed to determine temperature and the control mechanism in the spherical graphite geometry.
Frost Growth in Regenerative Heat Exchangers: Part II — Simulation and Discussion
Authors: Shang W. , Chen H. , Evitts R. W. , Besant R. W. 
Published: November 2021

Abstract
In this paper a numerical simulation of frost growth is compared with experimental data that was taken for similar operating conditions as those for regenerative wheels. One set of simulation results for the frost growth model (Part I) is presented to predict frost growth in a regenerative wheel with a cold supply air temperature of −40 °C, a warm exhaust temperature of 20 °C and 50% relative humidity. Cyclic and longer time duration frost properties are presented along with the spatial distribution of frost within the wheel. It is concluded that frost blockage effects will become very significant in only 20 minutes of operation.
Natural Convection Influenced Ice-Water Systems Contained Between Concentric Spheres
Authors: Sinton D. A. , Baliga B. R. 
Published: November 2021

Abstract
A computational study of natural convection influenced ice-water systems contained in the annular space between two concentric isothermal spheres is presented. An adaptive-grid control-volume finite element method (CVFEM) formulated for the solution of two-dimensional planar and axisymmetric problems was used in the computer simulations. The grid was designed to delineate the solid-liquid interface using a structured adaptation technique. In this study, attention is limited to three different two-dimensional axisymmetric, steady state, pure ice-water systems, with buoyancy-driven natural convection in the liquid phase: two of these systems involve ice adjacent to the inner sphere, and one system involves ice adjacent to the outer sphere. The dimensionless parameters are the following: a modified Rayleigh number, a density inversion parameter, the Prandtl number, radius ratio, and a temperature ratio. The results presented include solid-liquid interface shapes, streamlines and temperature contours in the liquid phase, and dimensionless local heat flux distributions along the surfaces of the inner and outer spheres, and the interface.