bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling, Analysis, and Experimental Testing of ABS Systems With Load Shifting
Authors: Mills Val , Samuels Bernard , Wagner John , Smith James , Layton Richard 
Published: November 2021

Abstract
The steerability and stability of vehicles must be maintained during emergency stopping and evasive driving maneuvers on degraded roads. The introduction of antilock brake and traction control systems has expanded the envelope of safe vehicle operation. ABS development has traditionally depended on extensive in-vehicle testing, at proving grounds, which contribute to lengthy product development cycles. However, recent attention has focused on laboratory wheel testers and hardware-in-the-loop strategies to emulate test conditions in a controlled setting to shorten product design time and address critical safety issues. In this paper, the effect of transient load shifting due to cargo movement on ABS system performance will be studied. Analytical and empirical mathematical models are presented to describe the chassis, tire/road interface, wheel, and brake modulator dynamics. These models have been integrated into a simulation to allow the study of transient weight transfers on the vehicle’s overall stopping distance and steerability. Experimental test results will be gathered on a single wheel tester which has been fabricated. The analysis of the numerical and experimental results will allow the ABS system performance to be predicted for various loading conditions and establish an envelope for safety critical testing during the product development process.
Validation of a New Closure Model for Flow-Induced Alignment of Fibers
Authors: Imhoff A. , Parks S. , Petty C. , Bénard A. 
Published: November 2021

Abstract
A closure model for flow-induced orientation of short fibers is presented and discussed. The model retains all the six-fold symmetry and contraction properties of the fourth order tensor. A derivation of the model is presented and the conditions required for the model to be realizable are discussed. The model is validated against analytical and numerical solutions of the exact distribution function for the fiber orientation state for different flow fields. Variations of this model and its limitations are also discussed.
Higher Order Singularities and Their Energetics in Elastic-Plastic Fracture
Authors: Im Seyoung , Jeon Insu 
Published: November 2021

Abstract
The higher order singularities[1] are systematically examined, and discussed are their complementarity relation with the nonsingular eigenfunctions and their relations to the configurational forces like J-integral and M-integral. By use of the so-called two state conservation laws[2] or interaction energy, originally proposed by Eshelby[3] and later treated by Chen and Shield[4], the intensities of the higher order singularities are calculated, and their roles in elastic-plastic fracture are investigated. Numerical examples are presented for illustration.
Probabilistic Failure Analysis for Composite Laminates
Authors: Herrington Paul D. , Schilling Paul J. 
Published: November 2021

Abstract
Considering the increasing applications of composites as structural components, the reliability of these materials is an important issue. Given the inherent variability of the material properties of composites, a probabilistic approach to the design of these materials is required. In this paper, the first-order second-moment method, coupled with the Tsai-Wu interactive failure criterion, is used to determine the reliability of composite laminates under various plane stress conditions. Uncertainty in material and loading parameters are considered. The method considered requires only the first two moments of the basic variables as input. This factor, along with its ease of use, makes this technique attractive to designers. Numerical examples, along with plots of the effect of coefficient of variation on the safety index, are given for a typical glass/epoxy composite.
Theoretical Modeling of Ice Formation Using Direct Contact Heat Exchange
Authors: Chau David S. , Phelan Patrick E. , Wood Byard D. 
Published: November 2021

Abstract
Theoretical modeling of a column type of direct contact heat exchanger was performed to predict the refrigerant evaporation and ice formation processes. There are a number of factors influencing the heat transfer rate-dependent evaporation of refrigerant and formation of ice. Among these are the size of the refrigerant droplets as injected, the local temperature and pressure, the heat transfer coefficient, and the temperature difference between the fluids. Differential equations are written for a general location in the flow, which express the conservation of energy and mass for the various species in the multiphase flow. The equations are solved stepwise from the initial injection location of the refrigerant to the location at which the entire refrigerant has become vapor. The theoretical modeling of the refrigerant evaporation and ice crystal growth processes is performed to determine the refrigerant bubble growth rate and the ice crystal growth rate in order to predict the refrigerant evaporation time and the size of the ice crystals.
Transient Modeling Results of a Methane-Steam Prereformer
Authors: Liese Eric A. , Gemmen Randall S. 
Published: November 2021

Abstract
A transient model for an external, counter-flow heat exchange, methane-steam reformer was presented previously (Liese et. al., 1999). In the present paper, a similar model is developed to simulate a simple tube geometry prereformer with no external heat addition. Model results are presented. First, a steady state analysis is shown for two prereformer geometries of equal catalyst volumes and residence time, but different superficial velocities. Second, common assumptions about the catalyst particle surface temperature are discussed, and a quasi-steady calculation of the particle surface temperature is presented. Startup and flow transients are shown for catalysts of low and high conductivites, and comparisons are made.
Discussion and Analysis of Flue Gas Utilization in a Phosphoric Acid Fuel Cell Engine During Idle Operation
Authors: Betts Daniel A. , Roan Vernon P. , Fletcher James H. 
Published: November 2021

Abstract
Fuel cell technology has in recent years won the favor of all major car manufacturers as a likely future replacement of the internal combustion engine. This has been driven by the potential for high efficiency and low emissions. Still, fuel cell engines must overcome major hurdles before being introduced into the market. One such hurdle is systems integration; in particular with fuel cell engines that do not use hydrogen as their primary fuel. In these engines, fuels, such as methanol, are employed instead of hydrogen because of their high energy density and ease of storage. However, these benefits are counterbalanced by the need to reform these fuels on-board the fuel cell vehicle, thus substantially increasing the complexity of the fuel cell engine.
Through the course of operating a 30ft methanol-fueled phosphoric acid fuel cell bus, repeated overheating of the steam-reformer catalyst bed at low engine power outputs was noted. For the purpose of better understanding these overheating events, relevant data was obtained from the bus. Bus operation at low power outputs was found to have low hydrogen consumption (∼40% to ∼60% of the stack’s incoming hydrogen) due to low electrical demands and reformate flow rate constraints. In the bus, the anode flue gas is burned in the reformer burner, which provides the heat required for the endothermic methanol steam reforming reaction (see fig.1). At low engine power, the flue gas is the reformer burner’s only fuel, but the energy carried by the flue gas is much greater than the energy required for the reforming reaction and consequently causes reformer overheating at low power.
This case serves as an example of how appropriate fuel cell system integration is crucial in order to harness fuel cell benefits. To study such system integration problems a steady state model of the fuel cell bus engine was developed. Using this model the bus reformer overheating problem was understood and several possible improvements for utilization of the flue gas were conceited.
Energy Supply Systems Based on Micro Gas Turbines for Industrial Applications
Authors: Bach Inger , Widell Karl Erik , Schmidt Geert V. 
Published: November 2021

Abstract
Denmark has a well-developed natural gas distribution grid and during the last decade a large number of decentralised CHP-plants (&gt; 2000 MW total capacity) have been built around the country for industrial applications and district heating. The largest small scale CHP has an installed electrical capacity of 99 MW, while most of the plants have capacities from some hundred kW to 10 MW. The larger plants are all based on gas turbines while the smaller plants predominantly use lean-burn reciprocating engines. On the whole this development has been very successful and is supported by tax incitements for small power producers. Lean-burn engines have, however, some problems, e.g. with regard to UHC, so the emergence of small and micro-gas turbines from a number of producers offers an interesting possibility to extend the use of gas turbines down to the smaller plant sizes.
Two cases have been investigated involving smaller industries with a process steam demand.
The energy systems investigated are based on a 100 kW recuperated gas turbine (Turbec T100) and a 600 kW simple cycle gas turbine (Volvo Aero VT600). The steam and hot water is produced in a Waste Heat Recovery boiler (WHR). To obtain the sufficient steam production and sufficient steam quality it is necessary to use supplementary firing.
The analysis shows that a recuperated gas turbine has no particular advantages for industrial steam production plants. The low exhaust temperature after the recuperator is not sufficient to produce steam of proper quality.
When comparing a CHP plant with a natural gas fired steam boiler, it is found that a simple cycle gas turbine is more suitable for steam producing industrial energy supply systems.
Even if the net electric efficiency is lower for a simple cycle gas turbine, one can get a quite high, marginal net electric efficiency of about 60% (LHV) when replacing a gas fired boiler with a steam producing industrial CHP-plant. The marginal net electric efficiency is based on comparing the actual CHP plant with an existing gas fired steam producing boiler with an efficiency of 90% (LHV). This is a very high net electric efficiency compared to a centralised power plant.
The study shows that there is little doubt that CHP systems based on gas turbines are functional, efficient and environmentally friendly, but it is very difficult to achieve a satisfactory economy with the present relations between gas costs, electricity prices and gas turbine prices.
Computational Code for the Management of a Deregulated Power Generation System
Authors: Bianchi M. , Gadda E. , Peretto A. 
Published: November 2021

Abstract
The European electric market is going to be fully liberalized moving the problems, related to the minimization of the electric energy production cost, to the Independent Power Producers.
In the present paper, a computational code, developed by the Authors, to discover the management strategy permitting to minimize the total variable cost (in terms of fuel consumption) required by a power generation system to face a specific load demand, is described.
Subsequently, the code has been applied to an existing power generation system comparing the fuel consumption in different management strategies.
It has also emerged that the code may represent an useful advice in the power generation system upgrading feasibility, calculating the fuel saving obtainable with the addition of new or repowered units.
Effects of Variation of the Overall Heat Transfer Coefficient in the Feedwater Heaters on the Thermodynamic and Economic Performance of Power Stations
Authors: Portacha Józef , Elfeituri Idris A. , Smyk Adam , Fiszdon Jerzy K. 
Published: November 2021

Abstract
This paper examines the effect of the variation of the overall heat transfer coefficient (U) in feedwater heaters on the thermodynamic and economic performance of a coal-fired steam power plant. The changes in the values of U are caused by the heat transfer surface fouling or by errors in the power plant design. These errors often result from the use of approximate heat transfer equations when selecting power plants elements.
Low and high pressure feedwater heaters of a power plant equipped with a condensing turbine and a natural circulation steam generator with one reheat stage are considered in this work.
The research was conducted using the overall heat transfer coefficients from 50% to 150% of the nominal value. The thermodynamic and economic effects on the power plant were calculated using the mathematical model of the power plant. The power plant components’ mathematical models evaluate the influence of the changes in the heaters’ overall heat transfer coefficient on the thermodynamic (especially exergetic) losses and economic effects. They take into account off-design operating conditions. The decomposition method and multi-level iterative process was used to solve the problem.
The research proved that, during operation, the capacity of the power plant might change by up to 2% due to above-mentioned variations. For a 600 MW power plant that means variation of the electric power delivery of approximately 12 MW and increase of the operating costs of up to 4 million dollars per year.
The obtained results are particularly useful in the decision-making process in planning renovation and feedwater heaters’ replacement periods.
Two-Phase Flow and Transport in the Interdigitated Air Cathode of Proton Exchange Membrane Fuel Cells
Authors: Wang Z. H. , Wang C. Y. 
Published: November 2021

Abstract
The two-phase flow and transport in an interdigitated air cathode is studied numerically by applying the multiphase, multicomponent transport model previously developed for conventional air cathodes. A computational fluid dynamics (CFD) technique is used to solve the two-dimensional model for the interdigitated air cathode, and the contours of oxygen concentration, water vapor concentration and liquid water saturation as well as the velocity vector fields of gas and liquid phases are obtained. A polarization curve is presented which includes both the single- and two-phase operating regimes. It is found that the threshold critical current density at which the two-phase zone begins to appear inside the porous cathode is higher than that of the conventional air cathode. The maximum liquid water saturation is found to be about 0.045 for a dry inlet at an average current density of 2.07A/cm2. Both gas diffusion and convection play significant roles in oxygen supply and water removal. A higher inlet relative humidity produces a more extensive two-phase zone in the interdigitated air cathode.
Computation of the Spectral Signature Behind a Jet Engine Using the Finite Volume Method
Authors: Badinand Thomas , Tamvel Heino , Fransson Torsten H. 
Published: November 2021

Abstract
A method is developed to compute the infrared signature behind a jet engine. The radiative transfer equation is solved with the Finite Volume Method (FVM) based on a double discretization of the spatial and the directional domain. Then, by solving step-by-step for different wave numbers for all directions, the value of the intensity received by a point placed at infinity looking at the computational domain with a defined angle and at a defined wave number is obtained. The resulting values of the intensity for a jet engine plume case compared very well with results from a validated ray-tracing model. A sensibility analysis has been carried out to assess the influence of the spatial and directional mesh, as well as the composition of the gas mixture on the results. The method appeared to be a very powerful and practical tool to study the spectral radiative signature created by a flow with arbitrary geometry.
An Introductory Course in Thermal Fluid Engineering
Authors: Sorensen I. , Ellis M. , Dancey C. , Vick B. , Jaasma D. , Diller T. 
Published: November 2021

Abstract
Experiences related to a new sophomore level course, “Introduction to Thermal Fluid Engineering,” are described. Several hundred students have taken the course and are currently enrolled in the follow-on courses in thermodynamics, fluid mechanics, and heat transfer. The introductory course is structured as a two-hour per week lecture with a laboratory that meets three times during the semester. Although thermodynamics, fluid mechanics, and heat transfer subjects are introduced sequentially during the course, the overlap and inter-relationships between topics are emphasized. It has been beneficial both for students and the faculty teaching the course to see the bigger picture of the three courses as a whole rather than as separate topics. The open laboratories are manned by a graduate student or senior who guides the students through hands-on experiments. Each of the three simple experiments is designed to illustrate important principles and reinforce the computational skills of the students. A web site has been established to help guide the students in preparing the written portion of the laboratory report. Team teaching of some sections has been tried and compared to the standard one teacher per section approach. Feedback from the students indicated a surprising acceptance of having several teachers for a course when they were well coordinated. One advantage mentioned by the students was to introduce them to more of the mechanical engineering faculty early in their studies. Because this is the first course requiring engineering analysis taught by the mechanical engineering faculty, it provides the opportunity to direct them in their problem solving and organizational skills that will be useful throughout the rest of their courses. Student evaluations are included as part of the results presented.
Unsteady Mixed Convection Over Spinning Isothermal Bodies With Blowing and Suction
Authors: Öztürk Ayşegül , Ece Mehmet C. 
Published: November 2021

Abstract
Initial development of the laminar thermal boundary-layer flow over an impulsively started translating and spinning axisymmetrical isothermal body with blowing and suction in the case of mixed convection is investigated. Velocity components and temperature are expanded in series in powers of the square root of time. Leading, first and second order functions are obtained analytically and the third, forth and fifth order functions are determined numerically. Application of the general results to a sphere shows that buoyancy driven aiding and opposing flows help surface suction in retarding and surface blowing in facilitating the onset of flow separation respectively. Surface heat flux is increased near the front stagnation point due to the axial inflow created by the body spin and enhanced by the circulating flow inside the separated region. Surface suction is found to increase the heat transfer while the surface blowing decreases it. Aiding and opposing flows increase the surface heat flux around the front and rear stagnation points respectively.
Basic Research Towards the Development of a Noninvasive Cardiac Pressure Monitor Using an Imaging Modality
Authors: Oakley Barbara A. , Stiles David 
Published: November 2021

Abstract
The complex electrical permittivity of heparinized whole human blood was studied as a function of frequency between 50 MHz to 20 GHz at both atmospheric pressure (97.7 kPa absolute) and at 300 mm Hg gauge pressure (137.3 kPa absolute). Complex permittivity was found to decrease throughout much of the frequency range with this relatively small increase in pressure. Subsequent depressurization and repressurization of the same blood sample showed no change in permittivity with pressure, leading the authors to hypothesize that changes in permittivity seen with the first pressurization of the blood may be related potentiation of an unknown factor with pressure, which may be reversed in vivo but not in vitro.
Internal Heat Transfer to Power-Law Fluid Flows Through Porous Media
Authors: Rao B. K. , McDevitt J. P. , Vetter D. L. 
Published: November 2021

Abstract
Heat transfer and pressure drop were measured for flow of aqueous solutions of Carbopol 934 through a vertical tube filled with porous media. The heated stainless steel test section has an inside diameter of 2.25 cm, and is 200 diameters long. The porosity was varied from 0.32 to 0.68 by using uniform spherical glass beads. Uniform heat flux thermal boundary condition was imposed bypassing direct electric current through the tube wall. Over a range of the parameters: 45 &lt; Rea &lt; 7,000, 21 &lt; Pra &lt; 58, 0.62&lt;n (power-law exponent)&lt;0.80, 0.22 &lt; d/D &lt; 0.6, and the polymer concentration from 250 to 500 parts per million, the friction factor data for power-law fluids agreed with the Newtonian predictions. Heat transfer to power-law fluids increases with increasing Rea and Prw and decreasing porosity. A new correlation was proposed for predicting heat transfer to power-law fluid flows through confined porous media.
Binary Fluid Mixture and Thermocapillary Effects on the Wetting Characteristics of a Heated Curved Meniscus
Authors: Pratt David M. , Kihm Kenneth D. 
Published: November 2021

Abstract
An investigation of the thermocapillary effects on a heated, evaporating meniscus formed by binary fluid mixtures of wetting liquids in a vertical capillary pore system has been conducted. Experiments were conducted to primarily observe the wetting characteristics of the binary fluid mixture and how they are affected by the dynamics associated with the heating of and evaporation from a meniscus. The results have demonstrated that interfacial thermocapillary stresses arising from liquid-vapor interfacial temperature gradients that degrade the ability of the liquid to wet the pore can be counteracted by introducing naturally occurring concentration gradients associated with distillation in binary fluid mixtures without affecting the heat transport capacity of the system.