bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extensional Flow of a Model Long-Discontinuous-Fiber Filled Thermoplastic Melt
Authors: Creasy Terry S. , Advani Suresh G. 
Published: July 2023

Abstract
A computer-controlled elongational rheometer revealed the transient elongational behavior of a polyethylene (PE) melt filled with highly-aligned long-discontinuous-fibers. Nylon monofilament of 0.50 mm diameter was the filler at 60 % volume fraction. A modified weaving process produced preform plys with controlled fiber length and fiber overlap distribution. Two fiber length-to-diameter ratios (L/D) of 25 and 100 afforded significantly different levels of viscosity increase. Extension rates from 0.001 to 0.1 s−1 at 140 °C established the response of each L/D ratio to increasing strain rate.
Cone-and-plate and capillary rheometers characterized the neat PE shear viscosity at 140 °C. A shear cell model suggests that highly aligned, high fiber volume fraction melts react to global extensional deformation with a local shear flow of greater magnitude. The elongational viscosity of the filled melt combined with the micromechanics of the model yielded values of matrix shear viscosity with a strong correlation to the PE Carreau behavior.
The Compressibility and High-Rate Shearing Response of a Lubricant: Experiments and Molecular Modeling
Authors: Zhang Yongwei , Ramesh K. T. 
Published: July 2023

Abstract
Knowledge of the rheological behavior of lubricants is crucial to the understanding of the lubrication process. We have studied the behavior of a synthetic lubricant (with a simple molecular structure) under high pressures and high shear rates using the pressure-shear plate impact technique. Our experimental results combined with results from other researchers show that this lubricant exhibits substantial compressibility as well as a strongly non-Newtonian shearing response. In an effort to develop a fundamental physical and mechanistic understanding of lubricants, we present here an analytical and computational investigation of the nonlinear compressibility based on estimates of the molecular structure and intermolecular interactions. An intermolecular interaction energy potential is obtained through relatively simple molecular mechanics calculations, and it is used together to predict the compressibility. It is shown that when the molecular conformation is allowed to evolve, the interaction potential provides a reasonable prediction of the material’s compressibility.
Effects of Electrical Change on the Shear Stress in ER Fluids (Frequency Response)
Authors: Tsukiji Tetsuhiro , Tanaka Norihiko 
Published: July 2023

Abstract
The frequency response of ER fluids in steady shear to sine-wave changes in the applied electric field is investigated. The ER fluids used in the present study consist of cellulose suspended in silicone oil. The size of cellulose particles is typically about 10∼20μm and a viscosity of silicone oil is 10mm2/s. Cellulose concentration is 20 wt. % and the percentage of moisture content is 0.6 %. Unipolar wave electric fields are used and the shear rates of 120 s−1, 400 s−1 are employed. Amplitudes of the electric fields are 0.1 and 0.4 kV/mm and DC component is 0.5 kV/mm. The frequency of the electric fields is changed from 0.1 to 1000 Hz. The rheological properties of ER fluids are carried out using rotational viscometer which is improved to apply the electric field on the ER fluids. The central value, the amplitude and the phase angle of the shear stress are measured. Dependence of the shear stress on electrical excitation frequency is investigated.
Electrorheological Response in an Emulsion System
Authors: Pan Xiao-Dong , McKinley Gareth H. 
Published: July 2023

Abstract
We report here the first studies of the electrorheological (ER) effect in a liquid-liquid emulsion, which is composed of a silicone oil and a chlorinated paraffin oil, with a thousand-fold difference between the bulk conductivities of the two components. Transient response of the viscous shear stress exerted by the emulsion is examined following step changes (on or off) of an external DC electric field oriented perpendicular to the original flow direction. For emulsions with a volume fraction of silicone oil Φ within the range 0.10 ≤ Φ ≤ 0.90, the relative change in the shear stress is found to increase with the volume fraction of silicone oil at low values of imposed shear rate. Large differences exist between the relative ER response strengths of an emulsion with volume fraction Φ and the corresponding phase reversed system of volume fraction (1 − Φ).
Performance Evaluation of a Heat Pump System With Near Azeotropic Refrigerant Mixtures of R-32, R-125, and R-134a
Authors: Goswami D. Y. , Mathur G. D. , Gupta S. , Kuo W. 
Published: July 2023

Abstract
Tests were conducted at the University of Florida’s Solar Energy and Energy Conversion Laboratory (SEECL) for evaluation of the performance of a residential 3 ton split unitary heat pump system with near azeotropic refrigerant mixture. The performance of the heat pump system was tested in accordance with the ARI Standard 210/240 (ARI 1989) and ANSI/ASHRAE-37-1988 for testing unitary equipment. ASHRAE’s “Air Enthalpy Method” was used to determine the performance of heat pump system and ASHRAE’s condition “A” [Outside 95°F DBT/75°F WBT; Inside 80°F DBT/67°F WBT1 was maintained for the tests.
Initial base line tests were conducted on the system with R-22 with an orifice for expansion. The system was then tested with near azeotropic refrigerant mixture of R-32 (30%)/R-125(10%)/R-134a(60%). The subcooling and superheat at ASHRAE condition “A” were matched with the base case with R-22. The performance of the system with the refrigerant mixtures of R-32/R-125/R-134a was lower by approximately 4–5% in comparison to the base case with R-22.
A Transient Analysis of Frost Formation on a Parallel Plate Evaporator
Authors: Martínez-Frías Joel , Aceves Salvador M. , Hernández-Guerrero Abel 
Published: July 2023

Abstract
This paper presents the development of a transient model for evaluating frost formation on a parallel plate evaporator for heat pump applications. The model treats the frost layer as a porous substance, and applies the equations of conservation of mass, momentum and energy to calculate the growth and densification of the frost layer. Empirical correlations for thermal conductivity and tortuosity as a function of density are incorporated from previous studies. Frost growth is calculated as a function of time, Reynolds number, longitudinal location, plate temperature, and ambient air temperature and humidity. The main assumptions are: ideal gas behavior for air and water vapor, uniform frost density and thermal conductivity across the thickness of the frost layer; and quasi-steady conditions during the whole process. The mathematical model is validated by comparing the predicted values of frost thickness and frost density with results obtained in recent experimental studies. A good agreement was obtained in the comparison.
The frost formation model calculates pressure drop and heat transfer resistance that result from the existence of the frost layer, and it can therefore be incorporated into a heat pump model to evaluate performance losses due to frosting as a function of weather conditions and time of operation since the last evaporator defrost.
Equilibrium Dynamics: An Unconventional View of Some Fundamental Physical Phenomena
Authors: Anderson Thomas P. 
Published: July 2023

Abstract
The thermodynamic formalism developed by Callen is extended to include mechanical and electrical as well as thermal systems. The entropy is postulated to be a continuous, homogeneous, first order function of all of the physical quantities that are absolutely conserved. Each of the conserved quantities is itself a function of time. For a simple system, characterized by energy, three components of linear momentum, and electric charge, the conditions for equilibrium are then used to identify and define the system temperature, velocity vector, and electrical potential as state variables. For a thermodynamic system the volume and mole numbers are added as fundamental extensive variables with pressure and chemical potential being defined as their corresponding intensive variables. Additional system variables, fifteen scalar and six vector, are concisely defined in terms of the fundamental relation. Then, by introducing three equations of state and drawing relatively effortless deductions from the postulates, the major features of mechanics, including relativistic and quantum mechanics, thermodynamics, and electromagnetics are developed. Thus the theory of EQUILIBRIUM DYNAMICS is shown to provide a common origin for much of the physics that is the basis for modern engineering applications.
A Simulation of Energy Utilization and Technological Change in the Pulp and Paper Industry
Authors: Hyman Barry , Roop Joseph M. 
Published: July 2023

Abstract
The ITEMS software package is used to simulate adoption of energy-efficient technologies in the paper industry under several scenarios. The simulation is calibrated so that the reference year replicates the 1991 fuel utilization and end use patterns in the paper industry.
This paper describes the main features of the ITEMS, including its technology database, the manner in which it simulates the key process steps in producing paper products, and the decision-making rules used in ITEMS regarding technology adoption. In addition, the paper describes the pulp and paper-making technologies included in the simulation. The value of ITEMS in assessing the impacts of R&D investments in energy-efficiency and other policy options is examined.
Principles for Thermodynamic Modeling and Analysis of Processes
Authors: Gaggioli Richard A. 
Published: July 2023

Abstract
A new formulation of Thermodynamics is presented, a variant of Gyftopoulos et al. (e.g., Gyftopoulos and Beretta, 1991, and Cubukcu and Gyftopoulos, 1995). Herein the presentation differs in at least two regards: (1) Alternative basic postulates, so the theory is more streamlined, and (2) Certain “philosophical” differences of viewpoint.. The latter is exemplified especially by views of what equilibrium means physically, and the ramifications regarding the concept of “state.” Other issues are the implications of measurements, their use for assigning scales (“units”, “dimensions”), their precision and that of models.
Regarding alternative postulates: Classically, entropy is developed by invoking reversible processes, and hence is defined only for “equilibrium states.” Gyftopoulos et al. have derived entropy so that it is defined for all states, so their theory is more general than the “classical.” Here, entropy is not derived but taken as a basic, underived concept — not only for “equilibrium states” (as in Callen, 1960, 1985) but for all states. Then thermodynamic theory is developed in a manner which is more straightforward and comprehensible, and probably more funedamental.
This paper also sheds light on the basics underlying thermodynamic modeling of processes and equipment, and upon exergy analysis. Principles are presented which are helpful to the thermodynamic development of models, and to exergy analysis (a separate issue).
Parameter Spaces and Design Optimization of Thermoacoustic Refrigerators
Authors: Wetzel Martin , Herman Cila 
Published: July 2023

Abstract
In the last two decades thermoacoustic refrigerators were developed in research laboratories with the goal to understand the basic physics and thermodynamics of thermoacoustic heat pumping. These research efforts led to a good understanding of this new environmentally safe refrigeration technology that employs acoustic power to pump heat. Consequently the next step is to improve and optimize the performance of thermoacoustic refrigerators and seek commercial applications. For this purpose, the need for fast and simple engineering estimates arises. By implementing the simplified linear model of thermoacoustic refrigerators — the short stack boundary layer approximation — such design estimates were derived and presented in this paper in form of a design algorithm. Calculations obtained with this algorithm predict values for the Coefficient Of Performance (COP) of the order of 5 to 6. These values cannot be achieved at this time because of loss mechanisms in key parts of the thermoacoustic refrigerator, which are not quite understood yet. Nevertheless, these values are encouraging and gaining a better understanding of these loss mechanisms will be a big step towards the commercial market for this new environmentally safe refrigeration technology.
A High Temperature Heat Pump With Methanol/Water Absorption
Authors: Kouremenos D. A. , Rogdakis E. D. , Alexis G. K. 
Published: July 2023

Abstract
The high temperature lift heat pumps required in many technical applications can not be achieved by conventional single stage absorption units. In recent years as solution of this problem have been proposed the multistage absorption cycles with many heat exchange units, control devices and a higher capital expenditure.
The purpose of this work is to investigate the posibility of a design of a methanol/water single stage AHP, capable to meet the high temperature lift heating requirements.
The lacking thermodynamic properties of the working medium are estimated at modest and higher pressures.
The results are given in correlations suitable for computer use as well as in diagrams.
A parametric study is conducted for the proposed unit in order to reveal the influence of the varius parameters on the performance of the cycle.
Novel Geometries for Hydronic-Air Heat Exchangers in Residential Space-Conditioning Applications
Authors: Garimella Srinivas , Coleman John W. , Wicht Andreas 
Published: July 2023

Abstract
The present study investigates the possibility of using highly compact, flat-tube/multilouver fin heat exchangers as replacements for conventional round-tube hydronic fluid-to-air heat exchangers used in space-conditioning applications. The advantages of these novel heat exchangers such as smaller frontal obstruction to air flow compared to round tubes (drag and fan power reduction), larger heat transfer coefficients due to the interrupted multilouver fins, and larger surface areas per unit volume can benefit absorption space-conditioning systems.
A comparison of the performance of this new geometry versus conventional round-tube heat exchangers was performed through the quantification of the decrease in heat exchanger mass for equivalent heat duties. Within the limitations of the available heat transfer and friction factor correlations, round-tube heat exchangers with flat, wavy, louvered and annular fins, and flat-tube heat exchangers with multilouver fins were designed to meet typical absorption cycle design conditions. The effect of design variables such as parallel/serpentine flow arrangements of tubes, fin densities, core depth, and other parameters on heat transfer performance and tube- and air-side pressure drops was investigated. It was shown that flat-tube heat exchangers can transfer equivalent heat duties while meeting pressure drop constraints with a significant reduction in the overall mass and size. Highly compact flat-tube, multi-louvered surface heat exchangers are being used to replace conventional round-tube/flat-plate fin geometries in automotive engine cooling and air-conditioning systems. These novel heat exchangers can benefit absorption systems, which are gaining increased attention as an environmentally friendly replacement for the CFC-based vapor compression cycles that are used in residential and commercial air-conditioning.
Exergy Evaluation of Two Current Advanced Power Plants: Supercritical Steam Turbine and Combined Cycle
Authors: Jin H. , Ishida M. , Kobayashi M. , Nunokawa M. 
Published: July 2023

Abstract
Two kinds of advanced power plants, a supercritical steam plant and a gas-steam turbine combined cycle, are analyzed with the aid of a methodology of graphical exergy analysis (EUDs). This analysis on the graphical EUDs provides detailed information on internal phenomena such as the driving force and distribution of exergy losses and/or waste in each process or subsystem. On the basis of the fundamental features of each plant, we recommend several schemes for improving the current advanced power plants.
Improving Turbine Performance by Cooling Inlet Air Using a Waste Heat Powered Ejector Refrigerator
Authors: Kowalski Gregory J. 
Published: July 2023

Abstract
Stationary turbines are used to produce electricity in many areas of the world. Their performance is adversely affected by high ambient temperatures. Several means of reducing the turbine inlet temperature (off peak water chiller and ice storage and absorption refrigeration systems) are being proposed as a means of increasing turbine output. In the present investigation the feasibility of increasing turbine output power by using its exhaust gases to power an ejector refrigeration system is demonstrated. The advantages of the ejector refrigeration are: it operates on a non-CFC fluid, its small number of moving parts and its small size. The analysis focuses on United Technologies FT4 turbine with a base load output of 21.6 MW. It is demonstrated that the proposed system can decrease the turbine inlet temperature from 296.2 K to 277.6 K which increases the turbine output by 12.8% during periods of high ambient temperature and improves yearly averaged power output by 5.5% in a temperate climate. It is shown that the energy in the turbine exhaust has the potential of producing additional cooling beyond that required to reduce the inlet temperature.
Parameters and Toxicity of Internal Combustion Engines Emission
Authors: Postrzednik Stefan , Żmudka Zbigniew , Ogierman Leonard 
Published: July 2023

Abstract
The relative emission indices of toxic substances (CO, NOx, HC, ...), one φp,i - in relation to the fuel consumption, and the other φe,i - to the power output, are defined. A general application of these indices for engine evaluation on the basis of toxic substances emitted, is proposed. The defined relative indices φp,i and φe,i depend on the operating factors, and by that explain the basis of the problem of toxic substances emission. For illustration, selected emission indices (for carbon monoxide CO, nitrogen oxides NOx, and hydrocarbons HC) in the whole operation range of Diesel engine SW400 and spark ignition engine 126A1.076/E, are presented. Additionally, as an instance, polycyclic aromatic hydrocarbons (PAH) were determined by means of the gas chromatography. Qualitative determination of 33 substances and quantitative determination of 13 substances were carried out. The developed algorithm and obtained results can be used to quantitative prediction of exhaust gas emission for the driving cycles and determination of the most appropriate running conditions of the tested engines.
A New Numerical Procedure for Simulation of the Gas Turbine Engine
Authors: Beyene Asfaw , Miller Andrzej 
Published: July 2023

Abstract
Mathematical model of the gas turbine engine (g.t.e.) requires formulation of the models of each of its components and framing their constraints and matching conditions to allow their operation as a unit system. Complexity of the g.t.e. configuration and the increase in the number of shafts impart an intricate multi-D mathematical model comprising from few tens to few hundreds of non-linear equations, at times yielding some serious numerical challenges.
There are a number of successful attempts made in developing “universal” codes to simulate performance of g.t.e. systems. QNEP [14], NEPCOMP [17], and NNEP [15] are some versions of codes developed for g.t.e. analysis. Most of these methods rely on successive substitution or the Newton Raphson method. Not too sensitive to the trial (initial) values and with high convergence chances, the later has been a powerful tool for system simulation of this nature. However, the Newton Raphson method can diverge if the trial solution is too far from the final solution or if the iterated value lies too remote from the physical solution. It is not capable of recognizing and avoiding a local minimum, or restrict the final physical solution to a region with useful practical application These are important attributes when tackling system simulation such as that of the g.t.e..
A new numerical procedure is introduced here as an expansion of the bisection method to solve the mathematical models of up to three-shaft designs covering all contemporary simple cycle configurations. The procedure was tested rigorously and proved to be globally convergent and adequately accurate, including for the problem it was designed. The method was used to simulate varieties of g.t.e. configurations with different points of useful power transmission, varying number of compressor and turbine stages, and flow direction of the working medium through multiple shaft systems. All such configurations were assumed to perform the same thermodynamic cycle, with identical design parameters.
Adaptive Vehicle Traction Force Control for Intelligent Vehicle Highway Systems (IVHS)
Authors: Lee Hyeongcheol , Tomizuka Masayoshi 
Published: July 2023

Abstract
This paper is concerned with robust longitudinal control of vehicles in the Intelligent Vehicle Highway Systems (IVHS) by adaptive vehicle traction force control (TFC). Two different traction force controllers, adaptive fuzzy logic control (AFLC) and adaptive sliding mode control (ASMC), are proposed and applied to the fastest stable acceleration/deceleration and robust vehicle platooning problems. The motivation for investigating adaptive techniques arises from the unknown time-varying nature of the tire/road surface interaction that governs vehicle traction. Synchronous application of the engine or brake torques is also proposed for more stable vehicle maneuvers. The lack of controllability during braking (only one net input torque for the two control objectives, i.e. front and rear wheel slips) is partly overcome by applying auxiliary engine torque. Simulations of the two control methods are conducted using a complex nonlinear vehicle model which fully describes the dynamic behavior of the vehicle. Both controllers result in good performance under time-varying operating conditions.
A Non-Linear Wheelset Model to Predict Derailment
Authors: Haque Imtiaz , McGirt Patrick , Nagurka Mark L. 
Published: July 2023

Abstract
The performance of a rail vehicle is a direct function of the ability of its wheelsets to negotiate the track. This paper presents the results from a detailed dynamic simulation study of wheelset motions with special emphasis on safety-related behavior. The wheelset is assumed to maintain continuous wheel-rail contact as it traverses smooth track that may be tangent or curved, and rigid or flexible. The model accounts for nonlinearities due to wheel-rail profile geometry and friction (creep) force and the longitudinal translation of the contact patch as a function of wheelset yaw angle. The results demonstrate non-linear features, such as limit cycles, and extremes of behavior including wheel-lift, and wheel-climb. The model has also been exercised to generate steady-state force and moment characteristics.