bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Simulation of Free Convection Heat Transfer From Localized Discrete Heat Sources in a Vertical Channel
Authors: Campo Antonio , Manca Oronzio , Morrone Biagio
Published: July 2023

This paper addresses the problem of natural convection cooled channels heated with flush-mounted discrete heat sources: this configuration is more realistic for the modelization of the cooling of electronic devices. The two-dimensional, laminar and steady-state problem is investigated numerically by the full elliptic Navier-Stokes and energy equations in a composite domain. The computational domain is I-shaped and is made by the channel and two rectangular reservoirs. The thermal behavior of a channel symmetrically heated by a single flush-mounted strip as function of the strip position with respect to the inlet section is investigated. Wall temperature profiles as well as the velocity and local Nusselt numbers as functions of the nondimensional coordinates are shown for channels heated by five strips per each wall. The analysis is carried out in the aspect ratio, height of plates/channel gap, and the Rayleigh numbers in the ranges 1–10 and 103–105, respectively. The wall temperature profiles show useful indications on the correct position of the heated strips with respect to the channel inlet in order to attain higher heat transfer rate coefficients. The velocity profiles at the inlet and exit sections are strongly influenced by the Rayleigh numbers. The local Nusselt values show that, for different values of the aspect ratio, the channels behave as uniformly heated walls at lower Rayleigh numbers. A correlation for the average Nusselt number in terms of Rayleigh channel number is given.
Prandtl Number Effect on Natural Convection Resonance
Authors: Antohe B. V. , Lage J. L.
Published: July 2023

We report on recent findings of natural convection resonance under time periodic horizontal heating. The transport phenomena is investigated numerically considering a rectangular enclosure filled with fluid or with fluid saturated porous medium. Numerical simulations, of various configurations, indicate that the natural convection activity within the enclosure peaks at several discrete frequencies, with the climax attained at a heating frequency referred to as the resonance frequency. A general estimate of the resonance frequency is obtained theoretically via a system of non linear equations, function of the average Rayleigh number, the Prandtl number, the enclosure aspect ratio, the heating amplitude, and the Darcy number for the porous medium case. Theoretical predictions considering various Prandtl numbers agree well with the numerical results. A simplified theoretical model antecipates the resonance frequency varying with Pr1/2 for the porous medium enclosure, a result confirmed by the numerical data. The convection intensity within the enclosure is shown to decreases with either increasing or decreasing Pr from its optimum value around 1. This behavior is explained as a dual effect: at low Pr the high thermal diffusivity reduces buoyancy inside the enclosure; at high Pr the high momentum diffusivity (viscosity) damps the flow wheel inside the enclosure. Both effects justify the observed reduction in the natural convection activity inside the enclosure.
Experimental Study of the Effects of Thermal and Solutal Convections in the Continuous Cast of a Binary Mixture
Authors: DeZego Shawn E. , Jones W. Kinzy , Dong Z. F. , Ebadian M. A.
Published: July 2023

An experimental study of the solidification process for the continuous cast of a binary NH4CI-H2O solution with varying inlet temperature and composition has been performed. Thermal and solutal density gradients have been found to strongly affect flow in the liquid region and are mainly responsible for the redistribution of species on the macroscopic scale. Flow visualizations have shown that dense solute-rich solution, rejected from the mushy zone, was redistributed into the upper regions of the liquid melt during cases of hypoeutectic initial concentrations. Localized remelting and shearing of columnar dendritic growth for the hypoeutectic cases and the redistribution and melting of equiaxed dendritic growth for the hypereutectic cases have also been found to strongly depend on the solution inlet temperature. It was established that the extent of equiaxed free solid that accumulated in the lower region of the liquid melt for the hypereutectic cases was dependent on the initial solution composition. Concentration histories show that segregation of species along the vertical centerline in the liquid pool have been measured to be in excess of 4% for some cases during quasisteady conditions. The warm buoyant solution entering the liquid melt via the feeding nozzle significantly increased convective effects that were not detected in previous research on static test sumps.
Experimental Study of Coupled Thermal and Neutronic Instabilities of Two-Phase Flows in a Boiling Channel
Authors: Rao Y. F. , Fukuda K. , Hashii N.
Published: July 2023

An experimental simulator is proposed for studying the mechanism of the two-phase flow instabilities in a boiling channel that involves coupled thermohydraulic and thermoneutronic feedbacks. In the experimental simulator, the thermohydraulic feedback loop is dealt with by a conventional two-phase flow heat transfer loop in which the coolant of water is circulated, while the thermoneutronic or void-reactivity feedback loop is partially simulated with a computer using the point-reactor model for the neutron dynamics and the lumped parameter model for the fuel dynamics to model the interaction between the average void fraction and the heating rate to the boiling two-phase flow. Experiments are conducted with varied fuel-time constants and void-reactivity coefficients to investigate their effect on the coupled instability. The experimental simulator is shown to be capable of revealing the fundamental characteristics of the coupled thermal and neutronic instabilities as have been discussed by previous analytical studies.
Enhancement of Critical Heat Flux in Subcooled Flow Boiling of Water by Use of a Volatile Additive
Authors: Pabisz Ronald A. , Bergles Arthur E.
Published: July 2023

The present investigation considers the effect of a 1-pentanol additive in water on the critical heat flux (CHF) and pressure drop in forced subcooled boiling. A small quantity of 1-pentanol was added to distilled water with the objective of getting an approximate 2% by weight mixture, which had been found to give superior performance in previous studies of pool and flow boiling.

Experiments were performed using stainless steel tubes with internal diameters of 4.4 and 6.1 mm. Tests were conducted with mass fluxes of 4400 kg/m2s, exit pressures of 9 bar, length-to-diameter ratios of 25, and exit subcoolings from 65 to 90°C. Test sections were heated directly by DC power, and critical heat flux data were inferred from test-section burnout. The alcohol concentration was periodically checked by draining off a sample and performing a Proton Nuclear Magnetic Resonance scan on the mixture.

At high subcoolings, the mixture exhibited an increase in the critical heat flux over that of pure water. However at low subcoolings there is a decrease in the critical heat flux. The increases in critical heat flux noted with the 1-pentanol mixture in this experiment were not as large as would be expected from saturated pool boiling results published by Van Stralen (1959). Pressure drop data for both the mixture and the pure water also were recorded. The 1-pentanol mixture, in general, exhibited larger pressure drops for the same conditions.
A New Tomographic Image Reconstruction Method: Using a Hybrid Genetic Algorithm
Authors: Lyons Donald P. , Kihm Ken D.
Published: July 2023

A new tomographic image reconstruction method is introduced using a hybrid genetic algorithm. Both traditional genetic algorithms and a hybrid genetic algorithm associated with the concurrent simplex method are described and the merits of each are discussed. For the purposes of discussion, results from simple axisymmetric phantom test data are shown for the traditional and the hybrid genetic algorithm approaches. This new methodology shows the potential of alleviating difficulties with existing tomographic algorithms under the constraint of limited projection data.
Stress Analysis and Design Improvement for Commercial Vehicle Frames With Bolted Joints
Authors: Kim Yoon Young , Kim Jin Gon , Choi Seok Hwan
Published: July 2023

Structural failures such as crack initiation often arise near the bolted parts of the side member and trunnion bracket of some commercial vehicles. To prevent these problems, a designer should be able to analyze with confidence the bolted joints of the structures, and this will require a reliable and practically simple bolted joint modelling technique. Once the modelling technique is established with experimental verification, the key design varibles must be identified in order to alleviate the level of the stress concentration near the problem region.

The purpose of this paper consists of two major parts: the establishment of a simple and practical bolted joint modelling technique and the determination of the key design variables for design improvement. Utilizing the established joint modelling technique, a number of finite element calculations are carried out for the analysis of the system consisting of the vehicle side member and trunnion bracket. The numerical results have indicated that the torsional rigidity of the frame cross section and the trunnion bracket size are critical design variables.
Vibration Transmission Characteristics of Helical Gear System With Lead Error
Authors: Park Chan Il , Lee Jang Moo
Published: July 2023

Nowdays reduction of gear noise in power transmission is very important, because the noise regulation is severe and demand of customer on noise is increased. To reduce gear noise, it is necessary to understand the vibration transmission characteristics of helical gear system. In this work, we designed test rigs for study of vibration transmission characteristics. By using these test rigs, root strain, rotational gear vibration, bearing vibration and sound pressure level are measured under varying rpm and torque. The frequency characteristics of rotational gear vibration and gear noise on the effect of lead error are discussed. Also, the relationship between gear vibration, bearing vibration and sound pressure level is discussed.
A Method to Predict the Precipitation Hardening Response of a Particle Strengthened Aluminum-Lithium Alloy
Authors: Fragomeni James M. , Hillberry Ben M.
Published: July 2023

Aluminum-Lithium alloys offer some attractive benefits over conventional aluminum alloys for aerospace structural applications. The benefits for the aerospace community include a weight-saving improvement as well as an increase strength and elastic modulus. The addition of lithium to aluminum increases the strength through heat treatment by a precipitation hardening process. This document describes an approach or method for predicting the precipitation hardening response for aluminum-lithium alloys using a given minimum number of experimental tests. The overall approach is based on the dislocation mechanics, particle coarsening, thermodynamics, and particle strengthening mechanisms applicable to precipitation hardened alloys. The method eliminates the need to know or determine several of the microstructural constants required for predicting the precipitation hardening response of a particle strengthened alloy. Thus, using the aluminum-lithium demonstration alloy, a minimum number of four tensile tests was utilized to predict the variation in strength with aging time, aging temperature, and composition, for the underaged, peak-aged, and overaged conditions.
Pulse and Power Three-Phase Plasma Generators, Possible Applications
Authors: Rutberg Ph. G. , Kolikov V. A. , Laskin B. M. , Safronov A. A. , Polovtsev I. S.
Published: July 2023

The existence of plasma generators with the ability to fit the requirements of different technological processes appears to be the basic point for the introduction of modern plasma systems. The use of plasma heat is one of the most promising areas for development in the chemical industry. Considerable intensification of chemical processes allows for reduction of the reaction area and processing time These factors allow creation of reactors with small overall dimensions, higher capacity and with more attractive economic characteristics.
Modeling of Thermal Treatment of Solid Wastes in Electric Arc Melters for Material Recovery
Authors: Wenger Ashley K. , Farouk Bakhtier , Wittle J. Kenneth
Published: July 2023

Processing hazardous solid wastes in a DC are melter offers several advantages over other competitive methods, including the ability to vary the mixture chemistry without impacting the energy input. This decoupling allows the melter to be operated in conditions which enhance material recovery. Predictive models can play a useful role in suggesting feed additives or operating conditions to achieve this goal. This paper describes the use of a model to investigate metal recovery through volatilization in batch melters. Chlorinated species are shown to be an effective additive; the potential to simultaneously treat solid wastes and chlorinated organics is also confirmed. At similar oxidation-reduction potentials the amount of chlorine, irrespective of molecular form, is found to determine the volatilization, with a linear relationship between chlorine feed amount and volatilization. In more reducing conditions, greater metal volatilization occurs.
Corrosion Screening Tests With Ni-Base Alloys in Supercritical Water Containing Hydrochloric Acid and Oxygen
Authors: Boukis N. , Franz G. , Friedrich C. , Habicht W. , Ebert K.
Published: July 2023

Corrosion of reactor material during oxidation of hazardous organic waste containing chloride proceeds very fast and constitutes one major problem in SCWO applications.

The following Ni-base alloys were tested within the framework of our experimental program: Inconel 625 and 686, Hastelloy C-276, Nicrofer 5923 and 6025, and Haynes alloy 214. Test tubes were fabricated from these materials and exposed to SCWO conditions, without organics, at temperatures up to 600 °C and pressures up to 34 MPa.

Higher concentrated HCl solutions or the combination of oxygen and HCl cause strong surface destruction.

The corrosion measured was higher at lower temperatures and at higher pressures, if all other conditions remained constant.

The most severe corrosion — general corrosion with SCC and pitting — appeared at temperatures near the critical temperature, i.e. in the preheater and cooling sections of the test tubes. The corrosion products were insoluble in supercritical water and formed thick layers in the supercritical part of the reactor. Under these layers only minor corrosion occurred.
Spray Unsteadiness in Coaxial Airblast Atomizers
Authors: Hardalupas Y. , Tsai R.-F. , Whitelaw J. H.
Published: July 2023

Experiments have been performed with two coaxial atomizers, the first with an annular stream of air surrounding a central jet of water and the second a commercial airblast atomizer with air swirl. They quantify the deterministic unsteadiness of the droplet flow caused by the break-up process in terms of the mean and temporal fluctuations of the droplet surface area and provide links between atomizing air and liquid flow conditions and the amplitude of the droplet flow unsteadiness with distance from the nozzle exit. Time dependent measurements of droplet surface area in the spray were obtained by image processing of high speed photographs to detect the temporal fluctuations of the attenuation of the incident light and by a Mie scattering technique to detect the intensity of the light scattered by droplets illuminated by a laser sheet. Mie scattering was preferred, because of improved measurement accuracy and lower cost. The spray unsteadiness due to the break-up process was quantified in terms of the spectrum of the energy of the fluctuations of the droplet surface area within a frequency range associated with the break-up process. With the coaxial atomizer, the energy of the deterministic unsteadiness varied between 50% and 65% of the total energy of the spectrum and remained in the droplet flow at least up to 150 liquid jet diameters downstream of the break-up region and its energy increased with the reduction of the air or liquid flowrates, although higher energy was correlated with faster attenuation with the downstream distance from the exit plane, caused by the redistribution of droplets by the gas flow turbulence.
A Sectional Coupling Approach for the Simulation of Multi-Phase Reacting Flow in a Bent Reactor
Authors: Chang S. L. , Zhou C. Q. , Lottes S. A. , Bouillard J. X. , Petrick M.
Published: July 2023

Multi-phase reacting flows of a bent fluidized catalytic cracking (FCC) reactor have been simulated using the ICRKFLO code. A new sectional coupling approach has been developed to handle the complex geometry, which divides the reactor into two sections at the bend and performs computations for the two sections successively. The computational results show that the ICRKFLO code incorporated with the new sectional coupling approach can predict product yields very well compared with experimental data and can be used to identify critical processes and parameters which may be modified to improve the quality and quantity of the FCC products.
Effects of Moisture on the Dynamic and Impact Properties of Pultruded Glass-Epoxy Composite Beams
Authors: Barpanda Dev , Kowsika Murthy V. S. L. N. , Mantena P. Raju
Published: July 2023

The pultrusion manufacturing process offers an increased market potential for the cost-effective production of high modulus and light-weight composite structural elements such as beams, trusses and stiffeners. These members must be qualified for performing over a wide range of in-situ conditions which include both static and dynamic loading under harsh environmental conditions. The interaction of these variables is expected to alter their dynamic and mechanical properties. To utilize the full potential of pultruded composites in structural applications, their response to environmental degradation must be thoroughly evaluated. In previous research, the effects of temperature, frequency, post-curing, along with the type and placement of fibers on the dynamic flexural properties of glass/epoxy and hybrid glass-graphite/epoxy pultruded composites were characterized. The sensitivity of damping and the glass transition temperature (Tg) to various levels of induced porosity and debonding agents was also investigated.

This paper presents the effects of moisture on the dynamic and impact properties of pultruded E-glass/epoxy (EPON 9500, a low Tg resin) composites with varying volume fractions. The dynamic mechanical analysis (DMA) technique was employed to investigate the degrading effects of moisture on the loss factor and Tg. Low-velocity impact tests were conducted on a similar set of specimens. An attempt has been made to correlate the impact characteristics in terms of crack initiation and propagation energies with the Tg and damping. Results indicate a lowering of the glass transition temperature with increasing moisture content along with an increase in the loss factor; which could be attributed to factors such as plasticization of the polymeric matrix, microcracks and debonding. This was accompanied by a reduction in the peak load to failure, initiation and propagation energies during impact. A reduction in the width of the glass-transition region was observed with an increase in moisture content, which is expected to have a detrimental effect on the long-term application of these pultruded composites.
Steady State Flow Between Two Rotating Cones
Authors: Ponsonnaille O. , Ouibrahim A.
Published: July 2023

The flow between two rotating cones has been widely considered for a best understanding of the performances of the centrifuges of type to plates which have applications in the alimentary industry.

Most of the theoretical investigations have considered the solutions of the flow between two rotating cones either by linearizations of the Navier Stokes equations, or by approximations from analysis of the different associated nondimensional flow parameters (such as Reynolds, Taylor, Rosby and Eckman numbers). In this work, the whole Navier Stokes equations are considered in such a flow and the solutions found by postulating the unknown velocity field components and the pressure as functions series. The three components of the velocity field are determined.

Experiments have been conducted in order to validate the theoretical results. L.D.A. velocity field measurements of the axial and tangential components have shown an agreement with the corresponding theoretical results.
Nonlinear Flow Properties of Viscoelastic Surfactant Solutions
Authors: Fischer Peter , Rehage Heinz
Published: July 2023

This contribution gives a quantitative description of nonlinear rheological properties of viscoelastic surfactant solutions. Therefore we compare the experimental observed rheological properties with the theoretical proposed material functions of the Giesekus model. A complete description of the linear and nonlinear properties is accessible especially by keeping the model’s free parameter constant. Further several empirically relations are automatically derived from the Giesekus model.
Viscoelastic Properties of Electrorheological Fluids
Authors: Choi Youn D. , Kim Sang G.
Published: July 2023

Electrorheological (ER) fluid’s storage shear modulus (G’) and loss factor (η) have been directly measured using small amplitude forced oscillating rheometer as a function of oscillating frequency, strain amplitude and applied electric field. Two types of experiment were performed; (a) frequency sweep and (b) amplitude sweep. Two kinds of sample were employed for this experiment; cornstarch in corn oil and zeolite particles in silicone oil.

The storage shear modulus (G’) was a strong function of driving frequency. Generally, G’ increased with driving frequency. On the other hand, the loss factor (η) was not well behaved as storage modulus, but as the driving frequency increases η slightly decreases was the trend of the material’s characteristics.

Also G’ was a strong function of strain amplitude. Generally, G’ decreased with increasing strain, but η increases slightly with increasing strain amplitude. For G’, cornstarch in corn oil ER fluid has higher values than zeolite based fluid as we increased the applied electric field. On the other hand, zeolite based fluid has higher values for η.

There is a reasonable agreement between theory and experiment.
Valve Stiction in Reciprocating Compressors
Authors: Prasad B. G. Shiva , Panayil Daniel
Published: July 2023

Stiction is a common phenomenon observed in day to day life. It also plays an important role in determining the dynamics and reliability of reciprocating compressor valves. However, researchers in the field of compressor technology have paid very little attention for assessing its effects, let alone for understanding the basic mechanisms responsible for its occurrence. Fortunately or unfortunately, it is also a problem of serious concern in magnetic recording devices, and researchers in the area of tribology have done comparatively detailed studies for understanding the same. Those studies have blamed molecular attraction, surface tension, viscous forces and micro capillary evacuation as the underlying causes for this phenomenon.

This experimental investigation concentrated mainly on identifying the dominant parameters and understanding the way they influence valve stiction. Experiments were conducted to quantify stiction in the case of a compressor valve, which was later modified and shown to reduce its effect.
Geometric Design and Analysis of an Axial Vane Rotary Compressor
Authors: Orndorff Raymond L. , Thompson Gregory J. , Smith James E.
Published: July 2023

Demand for smaller and more fuel efficient vehicles has brought about the need for smaller and lighter automotive air conditioning compressors. A relatively new rotary mechanism has the potential to fulfill this need. The mechanism is comprised of stators containing toroidal cams, vanes, and a rotor. The rotor contains equally spaced slots for the vanes to slide through.

Cam profiles are investigated to determine the desired vane motion for high speed application. Analyses are used with varying geometries to determine the effect of the geometric parameters on compressor performance. It was found that up to 90% of the vane’s frictional power losses could be avoided by allowing the cams to rotate. Volumetric efficiency could be increased by locating the cam lobes close to the rotor to form a dynamic seal. The bearing analysis found that with a certain numbers of lobes and vanes, the bearing loads are theoretically non-existent.
Exergy-Economics of a District Heating System
Authors: Cornelissen R. L. , Hirs G. G. , Lie A. B. K. , van Steenderen P.
Published: July 2023

The objective of this paper is to define the exergetic pay back period. This period can be used for energy efficient systems as part of a more general assessment also including financial aspects. For the conservation of the exergy of natural resources investments with a shorter exergetic pay back period will be preferable. To determine exergy savings of exergy efficient systems the exergetic life cycle assessment has been used.

As an example a district heating system in combination with a cogeneration plant based on natural gas has been selected. The irreversibility taking place during the life cycle of the system due to the construction, operation, dismantling and waste processing is determined and compared with domestic central heating also based on natural gas. The analysis has been performed for four alternative district heating systems. The exergetic pay back period, defined as additional exergy invested divided by exergy saving, is shown to be between 0.07 and 1.2 years. The life cycle exergy saving varies from 24% to 49%, mainly depending on the density of the distribution system. In addition the differences in exergy saving are due to the fact that the small scale alternatives have a smaller gas turbine, which has a lower exergetic efficiency when compared with the big scale projects.

There is no direct relation between the exergetic and financial pay back period in this study. However the financial pay back period is roughly one order of magnitude higher than the exergetic pay back period. From this can be concluded that heat distribution systems with exergetic pay back periods of more than one year have unacceptable financial pay back periods.
An Intuitive and Unified Approach to Teaching Thermodynamics
Authors: Çengel Yunus A.
Published: July 2023

In this paper a “physical” or “intuitive” approach is presented as an alternative to the current “formula based” approach to learning thermodynamics. The new approach is intended to keep the students in touch with the physical roots of the problem at all times, and it is based on the following four fundamental physical relations applied to the system being analyzed:

Mass balance: Mass change = Mass transfer

Energy balance: Energy change = Energy transfer

Entropy balance: Entropy change = Entropy transfer + Entropy generation

Exergy balance: Exergy change = Exergy transfer − Exergy destruction

The relations above are easy to remember and they are applicable to any kind of system undergoing any kind of process. Therefore, they can serve as the starting point for any kind of thermodynamic problem. In their present form, they make physically meaningful strong statements about the fundamentals of thermodynamics that mass and energy are conserved, entropy is generated, and exergy is destroyed during a process. They are sufficiently short to be used as formulas, and they can be used in place of numerous complicated first and second law relations provided that the mechanisms of mass, energy, entropy, and exergy transfer are well-understood.

In this paper we attempt to demonstrate that the basic principles of thermodynamics can be taught with this intuitive and unified approach faster and better. This approach also instills a solid and long-lasting understanding of thermodynamics in students. The proposed approach is intended to supplement the current approaches instead of replacing it. It is most suitable during initial stages of study of energy, entropy, and exergy to establish the physical reasoning behind the formulas, and to help students develop a physical feel. The approach naturally leads into the convenient formula-based approach when the students reach that maturity.
Introduction of Exergy Concepts Using Intuitive Methods
Authors: Petrescu Stoian , Petrescu Valeria , Harman Charles M.
Published: July 2023

Exergy or availability concepts in steady flow are presented in an intuitive manner through use of physical models and accompanying property diagrams. The concept of exergy is explained through the use of reversible steady flow shaft work. The Gouy -Stodola theorem is proven and the processes illustrated using property diagrams. Finally, a comparison is made of the Carnot cycle operated as an engine, as a refrigerator and as a heat pump and exergetic efficiencies are shown for each. The exergetic and energetic Sankey balance diagrams for each of the three cycles are combined and compared to show the similarities and differences in the use of the exergetic method.
Early Introduction of Entropy Concepts in the First Undergraduate Course in Thermodynamics
Authors: Smith Joseph L.
Published: July 2023

A new introductory course in mechanical engineering thermodynamics is described. The course develops the basic concepts as natural extensions of the students previous experience. The first law and the second law are developed simultaneously and with equal emphasis. Entropy, entropy transfer and entropy generation are introduced in a manner analogous to the introduction of energy, energy transfer and generation of heat. Extensive use is made of isolated systems for analysis so that all relevant relations are systematically identified. The PVT, energy and entropy constitutive relations for subsystems are presented separately from the first law and second law relations for a given problem. With the early introduction of entropy, all of the constitutive relations, including entropy, are described at the same time. The concept of mechanical-to-thermal cross coupling within the constitutive relations is introduced and related to the Maxwell-relation partial derivatives. The energy conversion requirement for cross coupling is developed. Control volume and flow system relations are developed from closed system relations in a conventional manner. The course ends with a description of the models for several important energy conversion plants and a discussion of the reason that all practical plants are flow systems.
A Desiccant Dehumidifier for Electric Vehicle Heating
Authors: Aceves Salvador M. , Smith J. Ray
Published: July 2023

Vehicle heating requires a substantial amount of energy. Electric vehicles (EVs) generate little waste heat, and using battery energy for heating may consume a substantial fraction of the energy storage capacity, reducing the vehicle range, which is one of the most important parameters in determining EV acceptability.

This paper analyzes the applicability of a desiccant dehumidifier for providing comfort heating in an EV with reduced energy consumption. A dehumidifier can reduce the heating load in a vehicle because it adsorbs the water vapor generated by the passengers, thereby avoiding water condensation on the windows without requiring a high external air ventilation rate or a high window temperature.

The results indicate that the desiccant dehumidifier can reduce the steady-state heating load by 60% or more under typical conditions. The reduction in heating load is such that waste heat may be enough to provide the required heating under most ambient conditions. Dehumidifier dimensions and weight appear reasonable for packaging inside an EV.
Yaw Rate Estimation for Vehicle Control Applications
Authors: Sivashankar N. , Ulsoy A. G.
Published: July 2023

This paper describes a method for vehicle yaw rate estimation using two accelerometers and a steer angle sensor. This yaw rate estimate can be used as an inexpensive alternative to commercial yaw rate sensors in vehicle control applications. The proposed method combines two complementary approaches to yaw rate estimation using accelerometers. This new method is superior to either method used by itself. This paper presents the new approach, supporting analyses and simulation results. The simulation results are based upon both linear and nonlinear vehicle dynamics models and include important effects such as sensor drift and noise, disturbances acting on the vehicle, and model uncertainties. These results indicate that the proposed yaw rate estimation scheme performs well for a wide range of operating conditions and is not difficult to implement.
Coordination Strategy for a Straight Line Split-μ Braking Maneuver
Authors: Venkataraman Shankar C. , Waldron Kenneth J.
Published: July 2023

A four-wheel steered vehicle is considered in which the front and rear steering angles and the brake torques at the wheels are assumed to be actively actuated. A split −μ braking maneuver is one in which the wheels on one side of the vehicle run into a surface with a low value of μ (coefficient of adhesion). In this situation the wheels on the high-μ side generate much larger braking forces than those on the low-μ side resulting in a yaw moment disturbance. Thus there is a direct conflict between achieving a short stopping distance against maintaining directional stability. It is common philosophy among ABS designers that in this situation directional stability is considered to be of higher priority than a short stopping distance. Several ABS design principles are used to enhance directional stability while compromising on the stopping distance. In this work, we develop a coordination strategy that does not sacrifice the stopping distance while maintaining directional stability.
Preview Control of a Superconducting Maglev Vehicle
Authors: Nagurka Mark L. , Wang Ssu-Kuei
Published: July 2023

A dynamic model of a magnetically-levitated (maglev) vehicle negotiating an elevated guideway is presented. The vehicle employs an electromagnetic suspension (EMS) system with canted magnets that provide simultaneous levitation and guidance. The modeling effort is focused on deriving a realistic dynamic model that includes a five degree-of-freedom nonlinear vehicle model, a superconducting magnet model, and a simply supported, multi-spanned guideway model. The maglev vehicle/guideway model is the basis for testing a proposed control strategy consisting of linear quadratic (LQ) optimal control with a preview (feedforward) feature. The LQ optimal control is augmented with integral action to avoid steady-state gap errors which might otherwise arise from guideway offsets. Simulation studies explore the effectiveness of the controller. The results reveal that the magnet module input voltages and gap errors decrease as the preview distance increases. However, the vehicle performance is limited due to a tradeoff between the carbody acceleration and the gap error.
Multivariate Cross-Coupling Adaptive Control Schemes to Reduce Contour Error in Multi-Axis Positioning Systems: Part II — Implementation and Experimental Results
Authors: Rober Stephen J. , Shin Yung C.
Published: July 2023

Modern Computer Numeric Controllers (CNC’s) for industrial milling machines focus on minimizing the tracking error of the individual axes of a multi-axis system. The contour error, which is defined as the minimum distance between the actual point and the desired contour, is minimized by matching the dynamics of each axis. The contour error is the factor which determines error in a machined workpiece. This paper presents the experimental results of the multivariate adaptive control algorithms presented in Part I of this work. These algorithms introduce controller cross-coupling into the algorithms for the specific goal of contour error reduction. Simulations with the existing control system, a fixed cross-coupling controller, and the multivariate adaptive cross-coupling controllers are presented for the comparison of performance. Experimental results of the existing controller and the adaptive control algorithms are then presented for various contours both without and with machining.
An Exoskelton Manipulator for Application of Electro-Magnetic Virtual Forces
Authors: Luecke Greg R. , Chai Young-Ho , Winkler John A. , Edwards James C.
Published: July 2023

This work addresses the fundamental need for continued improvement in human-machine interfaces. Of particular interest is the need for force feedback to the operator to provide the ability to interact physically with the synthetic environment. In order to allow for natural contact and control over the position, orientation, and motions of objects within the computer-generated environment, a new haptic interface device is under development that applies arbitrary forces to the digits of the human hand. This work describes the design and development of the hardware prototype of a robot manipulator intended to provide a force interface between a human operator and a computer-based dynamic model. The basis of the new device is in the coupling of the robot and human through the interaction of an electric current and a magnetic field. The device positions a strong magnetic field near wire coils mounted on the fingers, and forces are generated by electrical current moving within the magnetic field. The device consists of a mechanical exoskelton manipulator that maintains a constant position relative to the finger digits by means of an optical feedback tracking system. The kinematic linkage design of the exoskelton haptic interface device has been developed to maintain constant relative position of magnetic fields around the coils as each finger flexes through its range of motion. The relative position error is measured using a light source attached to the finger and a photo sensor mounted on the manipulator. The position of the exoskelton is controlled by correcting for the error between the center of the coil and the center of the magnetic yoke. The absolute position of the fingers is determined using the manipulator joint angles and the forward kinematic equations. The finger position is used as an input to the computer model, which generates appropriate interaction forces based on the inputs and the simulation parameters. The current prototype tracks one digit of the hand using two degrees of freedom, and can apply two independent virtual forces along the finger. The robot exoskelton is controlled by a digital computer, which combines sensor measurements with model simulation results to generate both trajectory and force commands. In this paper, the design and analysis of the mechanical exoskelton device and the development of a closed loop control algorithm to track the hand motion are discussed. A dynamic model of ISU exoskelton is developed and experimental results for the system are presented using some typical virtual environments, including interaction with a “hard” surface, a simple mass-spring-damper “yo-yo”, and interaction with a compliant “ball”. These results show that the electro-magnetic interface generates adequate force levels for perception of virtual objects by the exoskelton.
A Touch Display System for Interaction With Remote and Virtual Environments
Authors: Shimoga K. B. , Murray A. M. , Khosla P. K.
Published: July 2023

In this paper, we describe a touch display system suitable for dextrous interaction with remote and virtual environments. The basic framework involves a Utah/MIT robot hand, teleoperated by a human master wearing a VPL Data Glove. The touch reflection system consists of tactile sensors attached to the tips of the robot fingers and micro-actuators, also called tactors, attached to the finger tips of the human operator’s hand. Both the touch sensors and the tactors are commercially available. Experimental results demonstrate the usefulness of the touch display system in a context of dextrous telemanipulation.

The approach in this work, though not claimed to be novel, is however simple and inexpensive. The characterization of the force-sensitive resistors, used as touch sensors, and the compromises made on experimental results are of particular interest to the users of similar haptic displays.
When Is Vision Useful During a Familiar Manipulatory Task?
Authors: Klatzky Roberta L. , Purdy Kimberly A. , Lederman Susan J.
Published: July 2023

We asked at what point(s) vision is particularly useful for a simple and familiar peg-in-hole task. Experimental participants performed the task for 200 trials, 100 trials with full vision and 100 trials without vision or with vision at just one of four critical stages — prior to reach onset, when reaching for the peg, when grasping the peg, or when transporting the arm and inserting the peg into the hole. Comparisons of the mean time to perform under these conditions showed a graded forward effect of early vision, such that vision at initial stages facilitated performance at later ones, but with less and less effect on stages that occurred progressively later following visual offset. In most cases, vision was useful in the stage at which it occurred, but an important exception was the grasping stage. Vision provided at the point of grasping did not facilitate grasping but did affect transporting the arm and inserting the peg, as did vision during the transport/insert stage itself. Implications for direct and remote manipulation are considered.
Flexible Elements and Bond Graphs: A Lagrangian Approach
Authors: Redfield Robin C.
Published: July 2023

For situations where the flexibility of bodies contributes significantly to the overall dynamics of a system we implement a finite element approach to model the compliant part of the structure. One or more interconnected beam elements compose the flexible bodies. This allows bending about element-fixed local lateral axes and twist about the local longitudinal axis. Element flexibility is superposed on its rigid body motion with a Lagrangian approach in a Bond Graph framework. Structural inertia, stiffness, damping, and external loading are modelled. The development assumes given modes shapes and uses energy to formulate bond graph models of 2 and 3 dimensional elements subject to bending and torsion. Modal damping is also considered. Equations of motion are formulated from the graphs.
Ligament Forces During Isometric Contractions in the Intact and ACL-Deficient Knee
Authors: Shelburne Kevin B. , Pandy Marcus G.
Published: July 2023

A model of the knee in the sagittal plane was used to study the forces induced in the ligaments during maximum contractions of the quadriceps muscles. The geometry of the distal femur was obtained from cadaver data. The tibial plateau and patellar facet were modeled as flat surfaces. Eleven elastic elements were used to describe the mechanical behavior of the anterior and posterior cruciate ligaments (ACL and PCL), the medial and lateral collateral ligaments (MCL and LCL), and the posterior capsule. The model knee was actuated by eleven musculotendinous units, each unit represented as a three-element muscle in series with tendon. During maximum isometric extension in the intact knee, the model ACL is loaded from full extension to 80° of flexion; the model PCL is loaded at 70° of flexion and greater. The overall pattern of cruciate-ligament loading is explained by the interaction between the forces developed by the muscles and the shapes of the articulating surfaces at the knee. ACL forces in the range 0–20° of flexion depend most heavily upon the force-length properties of the quadriceps. As the knee flexes beyond 20°, however, cruciate ligament forces are determined by the geometry of the joint. Removing the ACL in the model leads to a substantial increase in anterior tibial translation relative to that found in the intact knee. Increased tibial translation generally manifests itself as an increase in the forces borne by the medial structures of the knee, and specifically by the posterior portion of the deep fibers of the MCL.
A Variable Structure Gradient Algorithm for Adaptive Control
Authors: Alleyne Andrew
Published: July 2023

A standard assumption in adaptive control is that the parameters being estimated are either constant or vary ‘slowly’ as a function of time. In this paper an adaptive control algorithm is presented which eliminates the need for the previous assumption provided that the systems being controlled belong to a specified class. The type of systems may be either linear or nonlinear. For this class of systems, the state space is separated into distinct subspaces. The parameters are then required to remain constant, or be slowly time varying, within the subspaces. Given a controller for the system, a Lyapunov analysis of the output error dynamics and the parameter error dynamics leads to a parameter adaptation algorithm with a variable structure. The stability and convergence of both the parameter error and the output tracking error are investigated. An analysis of SISO, full-state feedback, linear systems is used to motivate and illustrate the treatment of SISO feedback linearizable systems.
Optimal ℓ1 Control for Periodic Systems Under State Feedback
Authors: Aubrecht Johannes , Voulgaris Petros G.
Published: July 2023

The paper considers the minimization of the ℓ∞-induced norm of the closed loop in linear periodically time varying (LPTV) systems when state information is available for feedback. A state-space approach is taken and concepts of viability theory and controlled invariance are utilized. It is shown that a memoryless periodically varying nonlinear controller can be constructed to achieve near-optimal performance. The construction involves the solution of several finite linear programs and generalizes to the periodic case earlier work on linear time-invariant systems (LTI).
Asymptotic Analysis of a Tension Resonance Mechanism in Submerged Cables
Authors: Newberry B. L. , Perkins N. C.
Published: July 2023

Marine cables deployed in a fluid environment possess stiffness and drag properties which show strong directional dependence. This directionality significantly impacts dynamic cable response; particularly the dynamic tension developed due to environmental disturbances. This investigation focuses on one resonant dynamic tension mechanism that derives from nonlinear fluid/cable interaction. This mechanism is successfully captured using a discrete approximation to a continuous fluid/cable model as suggested by the results of a recent numerical study. An asymptotic solution of the discrete model is derived that reveals the principal fluid/cable parameters that control this tension resonance mechanism. The fidelity of the asymptotic solutions is also assessed through comparison with numerical solutions of the discrete and continuous models.
Durability and Damage Bahavior of 2-D and 3-D SiC/SiC Composites
Authors: Parvizi-Majidi Azar
Published: July 2023

An overview of the response of 2-D woven and 3-D braided SiC/SiC composites to thermomechanical loading up to a temperature of 1300°C is presented. The composites utilize Nicalon SiC fibers and are manufactured by the chemical vapor infiltration process. Fiber architecture controls the damage behavior of the composites both directly and indirectly by determining the sizes and distributions of microstructural pores within and between fiber bundles. The role of porosity on damage evolution is investigated by studying SiC/SiC composites with two porosity levels. A damage mechanics model based on Ladeveze’s approach is used to analyze the damage behavior of the composites. In addition to failure under tension, compression and bending, the fracture behavior of 2-D SiC/SiC composites is characterized through the application of various energy approaches based on the linear elastic fracture mechanics and J-integral methods. The toughness parameters thus obtained are compared and the suitability of the approaches discussed.