bluuebunny/crossref_metadata_2025_split huggingface dataset:
Damping in Brake Rotor Materials With Different Microstructures
Authors: Yang S. , Gibson R. F. , Li D. , Hecht R. L. 
Published: July 2023

Abstract
Flexural damping factors and flexural moduli of gray cast iron used for making automotive brake rotors and drums were measured from room temperature up to 700°C. The experiments were realized by the half power bandwidth method and the impulse-frequency response technique. Measurements were conducted on samples with different graphite flake morphologies and different Type A graphite flake sizes. The goal of this research was to study damping behavior and the influence on damping behavior of different morphologies, in order to ascertain that the optimized cast iron microstructure for suppressing brake noise and vibration is used for brake components.
Ultrasonic Characterization of Composite Material Stiffness Properties Using Genetic Algorithms
Authors: Balasubramaniam Krishnan , Rao Navin S. 
Published: July 2023

Abstract
In this paper, efforts on the ultrasonic measurements of material stiffness properties of fiber reinforced composites such as graphite-epoxy and glass-epoxy employing inverse methods based on Genetic Algorithms using noise-free oblique incidence data will be discussed. Phase velocity data as a function of the angle of refraction in non-symmetry planes for orthotropic uni-directional composite laminates were used as the input to the genetic algorithm. Optimal parameters were chosen from the sensitivity analysis of the stiffness constants using a direct approach. The inversion using this novel technique was extremely promising in computing the material properties from the ultrasonic phase velocity data. Advantages and disadvantages of such genetic search methods over conventional stiffness reconstruction techniques are also discussed.
Optimization of Composites Through Ultrasonic Characterization
Authors: Gérard A. , Raju P. K. 
Published: July 2023

Abstract
Composites offer the structural designer a wide choice of properties, geometries and characteristics. Various fibers, matrix materials,’ reinforcement geometries and processing histories may be combined to provide a composite with properties that range from isotropic, low strength and low stiffness materials to highly anisotropic, high strength, and high stiffness materials. These options offer additional variables to the designer that can be used to optimize the configuration of the material and structure simultaneously. This process is presented schematically in Fig. 1. Figure 1. shows a typical design cycle for a composite component.
Application of a Thick Beam Frequency Solution Library to the Rapid Identification of Elastic Constants of Thick Orthotropic Rectangular Plates
Authors: Zheng Zhiyang , Ayorinde Emmanuel O. , Gibson Ronald F. 
Published: July 2023

Abstract
The Rayleigh method is used to solve the forward problem of obtaining transverse vibration modal data of the thick beam, where through-the-thickness shear and rotary inertia are significant, for provided elastic constants. The vibration of the rectangular plate is then synthesized from those of beam’s in the plate’s main coordinate directions. In this paper, the forward beam solutions are taken from a pre-computed library, thus drastically economizing CPU time, since the process of elastic identification involves repeated trial solutions of the plate forward problem. An optimization scheme based on the difference between experimental and predicted frequencies is applied for the inverse problem, using the library values.
Linear Stability Analysis of a Planar Slurry Sheet With Gas Flow
Authors: Parthasarathy R. N. 
Published: July 2023

Abstract
A study of the break-up of planar slurry sheets subjected to gas flow was conducted using linear spatial stability analysis. Two models of slurry behavior were considered: (i) a dilute slurry with negligible particle-particle interactions, and (ii) a dense slurry displaying viscoelastic behavior. The gas was treated as inviscid. Dispersion relations were obtained relating the wave growth rates to the frequency and other variables. The wave characteristics were determined by numerical solution of the governing dispersion relations for a variety of conditions. It was found that the presence of particles decreased the disturbance growth rate without affecting the dominant wavenumber, in the case of a dilute slurry. For viscoelastic fluids, the Deborah number played an important role in the wave growth. In all cases, the gas velocity acted as a destabilizing agent.
Corner Singularities and High Weissenberg Number Asymptotics for Viscoelastic Fluids
Authors: Renardy Michael 
Published: July 2023

Abstract
Recent work on corner singularities in viscoelastic flows has shown that, in contrast to the Newtonian case, sharp boundary layers occur near the wall. These boundary layers can be viewed as a special instance of a more general phenomenon, which also occurs in other high Weissenberg number flows. This lecture reviews the derivation of boundary layer equations and their application, in particular to corner flow.
Collective Phenomena in Foam Motion Through Channels of Variable Cross Section and Porous Media
Authors: Bazilevsky Alexander , Kornev Konstantin , Rozhkov Aleksey 
Published: July 2023

Abstract
The flow of foam in a channel with regularly varying square cross-section was investigated both experimentally and theoretically. Observations show a new characteristic feature of foam motion: the forward lamellae of foam filling a wide “pore” of the channel create for themselves an effective liquid channel. The cross-sectional area of the effective channel is of an order of the throat area of original channel. Once the effective channel is formed, the following lamellae are free to pass through it. A simple theoretical model and some estimates of the yield pressure drop are presented.
High-Frequency Rheology of Fine Suspensions
Authors: Buyevich Yuri A. 
Published: July 2023

Abstract
In this paper, mean viscous stresses and interphase interaction in an essentially unsteady suspension flow are analyzed on the basis of a previously developed self-consistent rheological model. Fine suspensions prove to be dispersive media in the sense that the rheological properties they exhibited in monochromatic flows are frequency-dependent. Consequently, at any given moment, viscous stresses and the interphase interaction force depend on how flow kinematic characteristics had evolved up to that point. Viscous stresses and interphase interaction also feature three main relaxation processes, and the corresponding relaxation times remain approximately invariant throughout the whole frequency range. Our model is also applied to two problems of considerable practical concern. In the first problem, a shear wave penetrates into a suspension from an adjoining solid block. In the second problem, a pressure wave originates by impact of a heavy body upon the free surface of the suspension.
Thermal Radiation and the Thermal Management of Micro-Devices via Gaseous Flows
Authors: Baker J. 
Published: July 2023

Abstract
The impact of thermal radiation on heat and momentum transfer characteristics in gaseous micro-flows is explored. A model problem is formulated which incorporates a radiative source term in the energy equation and couples the momentum and energy equations through the use of Sutherland’s model for viscosity. The optically thin approximation is used to model the contribution of thermal radiation. Maxwell/Smoluchowski boundary conditions are applied at the solid-gas interfacial boundaries. Numerical results for flow fields with Knudsen numbers in the slip flow regime are presented. Comparisons are made between results with and without thermal radiation and with results from previously published analytical expressions. A parametric study is examined to determine the impact of various dimensionless quantities on flow field characteristics in micro-channel flows. Skin friction coefficients and Stanton numbers are also presented and discussed. Conclusions as to the importance of thermal radiation in effectively predicting micro-flow behavior are drawn.
Shortening the Defrost Cycle Time With Active Enhancement Within the Suction-Line Accumulator of an Air-Source Heat Pump
Authors: Nutter Darin W. , O’Neal Dennis L. 
Published: July 2023

Abstract
The heating seasonal performance factor (HSPF) of an air-source heat pump is degraded by the defrost cycle. Electric resistance heat was added to the refrigerant through the use of a 750-watt immersion heater inserted at the base of the suction-line accumulator and by heating the accumulator shell via a 900-watt electric band heater attached to the outside of the accumulator. The electric resistance heat and its hot metal surface was used as an active enhancement technique to increase the rate of refrigerant boiling during the initial few minutes of the reverse-cycle defrost. The unit was fully instrumented and equipped with two possible expansion devices: a short-tube orifice and a thermal expansion valve (TXV), for cooling / defrost mode operation and a TXV for the heating mode.
Tests were run in psychrometric rooms that maintained outdoor conditions at 1.7°C dry bulb and 80% relative humidity and indoor conditions at 21.1°C dry bulb. Overall performance characteristics of particular interest were integrated COP, cycle time, defrost cycle time, along with other instantaneous comparisons of power, refrigerant flow rate, temperatures and pressures. Tests with a 1.8 mm diameter orifice defrost mode expansion device and the immersion heater enhancement showed the best system improvement. This test had a 3.1% increase in integrated cyclic COP and a 11% reduction of the defrost cycle time. The reduced cycle time came primarily as a result of a 1.0 minute reduction (31%) of the outdoor coil post-melt (draining) time.
Performance Prediction of a Sub-Slab Heat Exchanger for Geothermal Heat Pumps
Authors: Nielson Eric , Braven Karen Den 
Published: July 2023

Abstract
A large portion of the installation cost of a ground-coupled heat pump system is for the excavation necessary for ground coil placement. One possible method of reducing this cost is to place the ground coils beneath the slab floor of the building. This configuration of ground coil placement has not been specifically addressed in previous research. Freezing of the soil must be avoided in such a system. To simulate the temperature response of the surrounding soil to heat pump operation, a computer model was developed which incorporates line source theory in the form of a system of rings. The fluid temperature change along the length of the coil was used to determine the distribution of the ground load throughout the ring system. The model includes an adiabatic upper boundary, seasonal soil temperature variation, and thermal interference throughout the system. This model was used to explore the effects of pipe spacing and flow direction on soil temperature response under various load conditions. Using these results, the minimum soil temperature over a season was predicted. Based on these results, design recommendations for ground coil installation are provided based on available area, soil type, heat extraction rate, depth of coil beneath the slab floor, and depth of slab floor below grade. These include recommendations for spacing between pipe loops, flow direction, and a method to determine whether this type of system is feasible for installation in a particular location.
Impact of Return Air Leakage on Air Conditioner Performance in Humid Climates
Authors: O’Neal Dennis L. , Rodriguez Angel , Davis Michael , Kondepudi Sekhar 
Published: July 2023

Abstract
An experimental study was conducted to quantify the effect of return air leakage from hot/humid attic spaces on the performance of a residential air conditioner. Tests were conducted in psychrometric facilities where temperatures and humidities could be controlled closely.
Return air leakage from hot attic spaces was simulated by assuming adiabatic mixing of the indoor air at normal conditions with the attic air at high temperatures. Effective capacity and Coefficient of Performance both decreased with increased return air leakage. However, power consumption was relatively constant for all variables except outdoor temperature, which meant that for the same power consumption, the unit delivered much lower performance when there was return air leakage. The increase in sensible heat ratio (SHR) with increasing leakage showed one of the most detrimental effects of return air leakage on performance.
On the Evolution of the Definition of Entropy From Clausius to Today
Authors: Gyftopoulos Elias P. 
Published: July 2023

Abstract
Carnot analyzed an engine operating between two reservoirs. Through a peculiar mode of reasoning, he found the correct optimum shaft work performed during a cyclic change of state of the engine. Clausius justified Carnot’s result by enunciating two laws of thermodynamics, and introducing the concept of entropy as a ratio of heat and temperature of a thermodynamic equilibrium state.
By appropriate algebraic manipulations, in this paper we express Carnot’s optimum shaft work in terms of available energies or exergies of the end states of the reservoirs, and Clausius’ entropy in terms of energy and available energy.
Next, we consider the optimum shaft work performed during a cyclic change of state of an engine operating between a reservoir, and a system with fixed-amounts of constituents, and fixed-volume but variable temperature. We express the optimum shaft work in terms of the available energies of the end states, and Clausius’ entropy in terms of energy and available energy. Formally, the entropy expression is identical to that found for the Carnot engine except for the difference in end states.
Finally, we consider the optimum shaft work performed during a cyclic change of state of an engine operating between system A initially in any state A, (thermodynamic equilibrium or not) and reservoir R. We call this optimum generalized available energy with respect to R, and use it together with energy to define an entropy of any state A,. Again we observe that the expression for entropy is formally identical to the two given earlier except for the difference in end states.
A Graphical Simulator for Teaching Design in a Thermodynamics Course
Authors: Nichols D. , Metghalchi M. 
Published: July 2023

Abstract
A thermodynamic cycle simulation package has been developed for the desktop computer. The package has been written completely in C++, to make it easy to maintain and to improve. The program is based on objects modeling each component used in a vapor power cycle. The package uses a graphical front end for creating cycles using a selection of icons for the different cycle components. The user is required to enter the minimal amount of data to define the operating conditions. The package will calculate the properties of the fluid at all states of the cycle and then determines the performance of the plant. The package can be used in teaching design of any thermodynamic cycle such as refrigeration, heat pump and gas turbine cycle, in addition to steam power plant. Although, currently only steam properties are provided.
Improvements of a Molten Carbonate Fuel Cell Power Plant via Exergy Analysis
Authors: Braun R. J. , Gaggioli R. A. , Dunbar W. R. 
Published: July 2023

Abstract
A proposed molten carbonate fuel cell power plant design, intended for commercial production by the end of the 1990’s and developed under the auspices of the U.S. Department of Energy and the Gas Research Institute, has been analyzed with exergy analysis. The commercial production units, targeted for dispersed power generation markets, are based on an existing demonstration molten carbonate fuel cell power plant design which entered the start-up phase in early 1996. Exergy analysis of the commercial plant design shows the overall, second-law system efficiency to be 53 percent. The principal inefficiency, 17 percent of the total, lies in the catalytic combustor. Another major inefficiency is the stack loss, 14 percent. Heat transfer accounts for approximately 6% of the loss. System reconfigurations, incorporating a steam cycle with reheat (System I) and a gas turbine cycle (System II), both with revised heat exchanger networks, for significant improvement are proposed and evaluated. The second-law system efficiency is raised to 66% in System I and to 70% for System II.
Thermoeconomic Analysis of Steam Turbines: An Approach to Marginal Cost Allocation
Authors: Royo Javier , Zaleta Alejandro , Valero Antonio 
Published: July 2023

Abstract
One of the main problems arising with the thermoeconomic optimization of energy plants, is marginal cost allocation in components containing a flow bifurcation. A typical example is a cogeneration steam turbine. The analysis of the marginal cost allocation of this type of turbine is rigourously studied in this paper.
Structural Theory (Valero et al., 1992; 1993) takes under consideration that marginal cost assessment depends on the marginal consumptions of the inlet flow for each outlet energy flow. Supposing that the behaviour of the turbine would not be affected by the quantity of mass flowing in the process, these marginal consumptions could easily be calculated (Royo and Valero, 1995). Nevertheless, the calculation of marginal consumptions under this supposition is only an initial approach to the problem.
The accurate values of marginal consumptions (and therefore of marginal cost) may be calculated if one knows the actual behaviour of the steam turbine. This is the process followed in this paper to obtain the values of the marginal consumptions of several cogeneration steam turbines. The analysis offers a complete knowledge of the marginal consumptions for different steam turbine characteristics that work under on-design and off-design conditions.
The results obtained are compared with respect to the above initial approach. It is shown that the errors appearing when assessing marginal costs in this way could be relatively important. Nonetheless, a series of correction terms is proposed, by means of which it is possible to considerably decrease these errors.
Precision Motion Control of a Magnetic Suspension System Using a Robust Nonlinear Compensation Scheme
Authors: Mittal Samir , Menq Chia-Hsiang 
Published: July 2023

Abstract
The article presents a robust nonlinear compensation algorithm for realizing large travel in magnetic suspension systems suffering from parameter variations, and external disturbance forces. A geometric feedback linearization technique that utilizes the complete nonlinear description of the electromagnetic field distribution is employed to obtain large travel. Robustness to uncertainties in the feedback linearized system is achieved through the development of a discrete time delay control based compensation algorithm. In comparison to previous developments, the new scheme removes the constraints of triangularity conditions in compensation of unmatched uncertainties. The performance of this algorithm is experimentally investigated on a magnetic suspension system. In each of the experiments, the controller is designed using the approximate nonlinear model of the system which is significantly different from the actual plant model. For a fixed set of gains, the robust nonlinear controller accurately stabilizes the system for a large range of ball positions. In trajectory tracking performance evaluation, the controller provides tracking accuracies that are of the same order of magnitude as the accuracy of the position sensor. Finally, when the suspended ball is impressed with an external disturbance force, the controller provides adequate model regulation and rejection of disturbance forces, demonstrating high stiffness control. The experimental results therefore, verify the consistent performance of the algorithm in realizing large travel inspite of parameter variations and external disturbances.
Implementation of Sensory Feedback and Trajectory Tracking in Active Telemanipulation Systems
Authors: Ephanov Anton V. , Hurmuzlu Yildirim 
Published: July 2023

Abstract
This paper presents an approach to the implementation of sensory feedback in a robotic telemanipulation system. The system considered here consists of kinematically similar master-slave robotic manipulators. We propose a control scheme whereby the slave tracks the motion commanded by the human operator through the master mechanism. The scheme also accommodates, in a unified manner, different sources of sensory feedback. These include combined effects of the interaction with unknown environments and changes in structural properties of the slave manipulator due to additional unknown loads. The control algorithm is based on continuously sliding variable structure control, which is a nonlinear and highly robust control scheme. Due to the robustness of the scheme, the need for a priori information about the environment and the load is minimal. This information can be passed on to the system in the form of upper bounds of the interaction forces and additional loads. Experimental studies with a Pneumatic Haptic Interface (PHI) system were conducted to evaluate the performance of the proposed scheme.
Calibration of Closed Loop Controllers for Setting Impedances in Force-Reflecting Systems
Authors: Jayachandran Vijay , Rahman Tariq , Salganicoff Marcos , Heredia Edwin , Harwin William 
Published: July 2023

Abstract
This paper discusses a new method of impedance control that has been successfully implemented on the master robot of a teleoperation system. The method involves calibrating the robot to quantify the effect of adjustable controller parameters on the impedances along its different axes. The empirical equations relating end-effector impedance to the controller’s feedback gains are obtained by performing system identification tests along individual axes of the robot. With these equations, online control of end-effector stiffness and damping is possible without having to monitor joint torques or solving complex algorithms. Hard contact conditions and compliant interfaces have been effectively demonstrated on a telemanipulation test-bed using appropriate combinations of stiffness and damping settings obtained by this method. Since the method is general in nature and can be used for finding possible relations between controllable parameters and quantifiable output behaviour of a system, it can be extended to calibrating and controlling impedances in poorly modeled robot-actuator systems. A limitation of this method is that the actuator being modeled must have very little friction.
Robot Impedance Synthesis Based on Logic Task Description and Progressive Learning
Authors: Yang Boo-Ho , Doubleday Rolland L. , Asada Haruhiko H. 
Published: July 2023

Abstract
A new approach to the synthesis of robot impedance for force-guided assembly is presented in this paper. An optimal impedance is generated based on the combination of logic task description and learning. First, desired behavior of a robot system for performing a given task is described at a logic level. A simple logic branch control using a quasi-static force-to-motion map is created based on the logic description of desired robot behavior. A new learning method, called “Progressive Learning,” is then applied to this logic branch control in order to create a dynamic control, i.e. impedance control, for performing the task quickly and dynamically. Starting with a simple logic description about the robot behavior, the system can develop a fully dynamic impedance control by progressively learning the process dynamics. The problem is formulated in the context of high-speed insertion, and the major theoretical results are verified through simulation.