bluuebunny/crossref_metadata_2025 huggingface dataset:
Reversible Aggregation and Nonlinear Rheology of Fine Suspensions
Authors: Buyevich Yuri A. , Zubarev Andrei Yu.
Published: July 2023

In this paper, we develop a tentative rheological model for finely dispersed systems whose particles are capable of forming stable aggregates under shear flow conditions. The main achievement of this paper consists in putting forward a physical model for an aggregative structural transition in a flowing dispersion. When shear rate reaches a certain threshold value, rapid aggregation occurs, the aggregates originate as a result of reversible coagulation of particles in a secondary potential minimum characteristic of the molecular interparticle interaction. The aggregated system consists of an assemblage of aggregates that contain many particles and that are suspended in an ambient media that represents a suspension of single individual particles. Aggregation terminates and aggregates disappear when shear rate exceeds another critical value. The aggregated system effective viscosity is determined by the volume concentration of the aggregates and by the volume concentration of single particles in the ambient suspension within the interstices. Since these concentrations, as well as the aggregate size, depend on the shear rate, the effective viscosity is a nonlinear function of shear rate. Our model offers an opportunity to describe both shear-thickening and shear-thinning of aggregating dispersions within the frames of a unified approach.
Extensional Flow of a Model Long-Discontinuous-Fiber Filled Thermoplastic Melt
Authors: Creasy Terry S. , Advani Suresh G.
Published: July 2023

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Integrated Modeling for Metal Removal Operations
Authors: Bailey Trevor E. , Jenkins Derek M. , Spence Allan D. , Elbestawi M. A.
Published: July 2023

An integrated CAD/CAM and machine tool control system is implemented to automate tool path generation, cutting condition optimization, and online supervisory control for semi-finishing and rough milling. The part is designed using a solid modeler, and tool paths are generated using a CAM system. A process simulator developed at McMaster University is then used to automatically schedule cutting conditions that maximize the Material Removal Rate (MRR) subject to cutting force, power, and chip load constraints. During actual cutting, the measured spindle power is compared to reference data supplied by the simulator. As the tool wears, the slow increase in spindle power consumption is used to override the scheduled feed rate without operator intervention. All components of the integrated system are designed around industry standard computer hardware, operating systems, solid modelers, and cutter location file representations.
Diagnosing Spindle Defects Using 4D Holospectrum
Authors: Chen Yuedong , Du R.
Published: July 2023

Spindle is one of the most commonly used mechanical devices in many industry sectors, such as large rotating machinery industry and machine tool industry. Diagnosing spindle defects, such as unbalance, misalignment, and crack, plays a very important role in reducing operation cost and maintenance cost. This paper presents a new method of diagnosing spindles using a newly developed sensor signal processing technique called four dimension (4D) holospectrum. The experiment results show that the spindle defects, including unbalance, misalignment and crack, have distinct features in the 4D holospectrum. These features have clear physical meanings and is quantitatively related to the spindle defects. Compared to the conventional spectral analysis and/or modal analysis methods, the new method is more suitable for computer automated diagnosis.
An Open Architecture Model of System Development
Authors: Birla Sushil , Egdorf Harry , Igou Richard E. , Michaloski John L. , Sweeney Douglas J. , Weinert George , Uchida David , Yen C. Jerry
Published: July 2023

Application of Open Architecture (OA) technology is a fledgling practice within the controller industry. OA solutions offer great potential and flexibility in the design and implementation of controllers. Yet, as an evolving technology OA controller development offers unique challenges compared with traditional project development. This paper will present an OA Life Cycle developed by the TEAM/ICLP API workgroup to assist its specification efforts. A high-level view of the Life Cycle will study the differences between a traditional and an OA Life Cycle model. A detailed Life Cycle model will present a practical treatment to the OA development activities and present the type of information required. The detailed OA Life Cycle model will study the development process from the perspective of the end user, the system integrator, and the component developer.
Multivariate Cross-Coupling Adaptive Control Schemes to Reduce Contour Error in Multi-Axis Positioning Systems: Part I — Design and Stability
Authors: Rober Stephen J. , Shin Yung C.
Published: July 2023

The majority of motion control systems in use today employ fixed controllers, such as PID, which are tuned for nominal system conditions. Such systems, however, suffer from performance degradation as the system dynamics vary from the nominal conditions. Furthermore, cross-coupling among axes of motion also affect the positioning accuracy in contouring, particularly as the speed increases. This paper describes adaptive control strategies to alleviate this problem by adapting controller parameters on-line to compensate for changing system dynamics. Control strategies for both minimum and nonminimum phase systems are presented including cross-coupling control between axes. Part I of two papers presents the design of the multivariate adaptive control laws with stability proofs and part II describes the implementation results for an end milling process. The control schemes presented here can be utilized for a wide range of tracking control problems.
Numerical Methods for the Haptic Presentation of Contact: Theory, Simulations, and Experiments
Authors: Ellis R. E. , Sarkar N. , Jenkins M. A.
Published: July 2023

An important problem in the field of haptic display devices and telerobotics is poor force reflection of contact, particularly of contact with stiff surfaces. There are numerous possible sources of poor performance, including poor contact models, sampling errors, and delays due to computation or data transmission. In this paper we examine effects due to sample-and-hold, which is a fundamental property of both the discrete domain and also of the sensors and power amplifiers used in a haptic-interface system.

We propose that the sample-and-hold concept be generalized to sample-estimate-hold. We show why ordinary zero-order hold generates an active contact interface, and provide ways of improving the feeling of the interface. We have developed a suite of numerical methods for improving the performance of haptic presentation of surfaces. We have conducted both simulations and experiments to demonstrate the efficacy of the proposed scheme. Our contributions are a new method of digitally processing force data, and a systematic method for coupling force-processing systems that run at different rates.
Left Versus Right Hand Differences in Exploratory Strategies: Facts and Relevance to the Development of Haptic Devices
Authors: Lacreuse Agnès , Fagot Joël , Vauclair Jacques
Published: July 2023

The literature provides conflicting results with regards to hand/hemisphere lateralization in haptic perception; while some papers report a left hand advantage for recognizing haptic forms, other studies indicate either a right hand advantage or no hand difference at all. Four experiments with right handed subjects will be presented, in which scanning strategies and performance were investigated when subjects touched nonsense forms by either the left or right hand. The research involved a novel apparatus and composite stimuli made of cubes whose junctions were not haptically discernible. During the inspection of the shape, the location and duration of any hand contact with the cubes comprising the stimulus were recorded, allowing thus an analysis of exploratory strategies. The first experiment implied the inspection of a target stimulus with either the left or right hand. Thereafter, subjects were requested to identify the drawing of the target stimulus displayed among different drawings. No hand differences were obtained in terms of scores. It was found, however, that in men the left hand touched the stimuli more globally than the right. In the second experiment, subjects were requested to inspect in simultaneity two forms with two hands (i.e., dichhaptic task), before recognizing the forms on the visual array. Here, the left hand outperformed the right hand. Moreover, as in the previous experiment, the left hand touched the shape more globally than the right. Results also demonstrated that only 20% of the total exploration time was devoted to a simultaneous inspection of the two forms. The two additional experiments focused on hand performance and exploratory strategies for recognizing the stimuli, instead of learning them. No hand differences were observed in strategy, whatever the mode of exploration (either dichhaptic or monohaptic). By contrast, recognition achieved by the left hand was better than that of the right hand, but this effect was restricted to dichhaptic recognition only. Overall, we conclude that this series of experiments demonstrates the reality of hand/hemispheric differences in the processing of haptic information by men. We argue, moreover, that these findings are of particular relevance for the development and use of haptic devices that are designed to display haptic information on body segments (e.g., tactile or force feedback devices). Firstly, they suggest a serious consideration of the laterality factor for stimulating subjects, in order to enhance pattern recognition. Secondly, they suggest that information presented to the left hand would be more easily processed if it was displayed globally, whereas information presented to the right hand would be more easily and efficiently processed when made available in a sequential manner. Finally, the results show a limited capacity to process two distinct sources of haptic information at the same time.
Estimation and Modeling of Human Hand Impedance During Isometric Muscle Contraction
Authors: Tsuji Toshio , Kaneko Makoto
Published: July 2023

The present paper examines human hand impedance characteristics with consideration of effects of muscle activity. While a subject maintains a given hand location with a specified muscle activation level or a hand force, small external disturbances are applied to his hand. The corresponding force-displacement vectors are measured to estimate the hand impedance by means of a second-order linear model. The main results of the experiments can be summarized as follows: (1) geometrical parameters of the hand stiffness and viscosity ellipses change depending on the muscle activation levels of the subjects, (2) both the stiffness and the virtual equilibrium point of the subject’s hand change depending on the amplitude of the generated hand force, and (3) hand stiffness and viscosity can be predicted from the joint angles and EMG signals of the subject’s arm.
Creating Artificial Damping by Means of Damping Injection
Authors: Stramigioli Stefano
Published: July 2023

This paper presents a way to design a “physical controller” for a robot which has to interact with the environment. Such systems need artificial damping in order to achieve proper interactive performances. A method of creating extra damping without the need to measure velocities will be presented.
State Feedback Control of Electrorheological Fluids
Authors: Radcliffe Clark J. , Lloyd John R. , Andersland Ruth M. , Hargrove Jeffrey B.
Published: July 2023

Electrorheological (ER) fluids have electrically controllable stiffness, viscosity, and heat transfer properties. Since the 1940s researchers have attempted to model the properties of ER fluids and have proposed applications which attempt to utilize their special characteristics in the operation of hydraulic valves, soft clutches, and active suspension systems. Early attempts to make these applications commercially successful were hampered by the relatively slow, nonlinear response of ER fluids under on-off control of high electric fields. Successful applications will require fast, precise control of the response of ER fluids, independent of application at low field strengths.

This study presents a new approach to the control of ER fluids that overcomes the problems of imprecise, slow, nonlinear response and high electric fields. An optical sensor was used to indicate the ER fluid state in a layered composite window. Feedback control of ER fluid state was developed and compared to conventionally actuated ER fluids. Feedback control employs the state sensor and high initial electric field strength to speed ER state response, then lowers the field strength to the minimum level required to achieve the desired ER fluid state. Predicted responses were compared to experimentally measured responses and showed excellent agreement. Laboratory measurements showed a proportional state feedback control system yielded an electrorheological fluid that responded 35 times faster and 21 times more accurately than possible with a conventional open-loop fluid control system. Although the use of ER fluids in feedback control systems have been proposed in the past, this work is the first application of feedback control to the fluid itself.
Dynamics of Robot Arms and Chains via Kane’s Equations
Authors: Müller-Karger Carmen M. , Townsend Miles A.
Published: July 2023

A new derivation of the equations of motion for robot arms and other dynamical chains is presented using the methodology of Kane’s equations. This approach combines the ease and intuition of Newtonian analysis with the capability to eliminate all non-working forces of constraint. The “monotony” of the system’s configuration is used to define the generalized coordinates and generalized speeds such that a universal and compact equation of motion was found which applies to any chain or robot arm configuration. This general, explicit closed-form eliminates much of the “overhead” of Kane’s methodology. A two-link manipulator example shows the implementation.
Wavelet Representation of the Ground Reaction Force Data
Authors: Sloboda William , Zatsiorsky Vladimir M.
Published: July 2023

The use of the wavelet transformation for analyzing ground reaction force (GRF) data is proposed and demonstrated. The method permits: (a) time localization of the wavelet coefficients which represent the contributions of varying frequency, e.g. high frequency oscillations are mainly present immediately after foot contact with the ground; (b) reconstruction of the signal from the coefficients; (c) estimation of the contribution of the low and high frequency components of the signal, in particular the percentage of energy in the original system accounted for by an individual frequency bandwidth, (d) document the differences in two vertical GRF signals through the energy at various frequency bands.
Robust Stabilization of Large Amplitude Ship Rolling in Regular Beam Seas
Authors: Chen Shyh-Leh , Shaw Steven W. , Khalil Hassan K. , Troesch Armin W.
Published: July 2023

The dynamics and control of a strongly nonlinear 3-DOF model for ship motion are investigated. The model describes the roll, sway, and heave motions occurring in a vertical plane when the vessel is subjected to beam seas. The system is installed with active anti-roll tanks as a means of preventing large amplitude roll motions. A robust state feedback controller for the pumps is designed that can handle model uncertainties, which arise primarily from unknown hydrodynamic contributions. The approach for the controller design is a combination of sliding mode control and composite control for singularly perturbed systems, with the help of the backstepping technique. It is shown that the current method can effectively control roll motions of large amplitude, including capsize prevention. Numerical simulation results for an existing fishing vessel, the twice-capsized Patti-B, are used to verify the analysis.
Proper Orthogonal Decomposition: An Efficient Means of Controlling Self-Excited Vibrations of Long Torsional Strings
Authors: Kreuzer Edwin , Kust Oliver
Published: July 2023

Self-excited vibrations of torsional strings can cause considerable problems during operation and in severe cases, they could damage the string. As an example for an extremely slender structure we consider a drill string for deep drilling for the exploration and production of oil and gas. The modeling and numerical simulation of the system will be given and the mechanisms of self-excited vibrations will be discussed by means of stability and bifurcation analysis.

In very long strings the dynamics is characterized by different trajectories over the length. For the analysis of the spatio-temporal properties and to gain insight into the complex dynamics we introduce proper orthogonal decomposition.

In order to minimize self-excited vibrations in torsional strings we present an active damping system by controlling the drive via feedback of the system’s state. The feedback law is formulated by a projection of the infinite-dimensional system state onto a real input variable. The basis of the projection is determined by proper orthogonal decomposition (POD). The design of the controller and the determination of the controller parameters by optimization are presented. The improvement of the dynamics is verified by simulations.
Nonlinear Dynamics of a Rotating Shaft Subject to Periodic Perturbations
Authors: McDonald Robert J. , Sri Namachchivaya N.
Published: July 2023

In this paper, we study the global dynamics of a rotating shaft parametrically excited by a time-dependent rotation rate. The partial differential equations of motion for the shaft are first discretized using the Galerkin procedure. The equations are rewritten as Hamiltonian equations in order to study the global dynamics of the system using the methods of perturbed Hamiltonian systems. After performing un-foldings and determining the normal form, the equations are put into action-angle coordinates, the most suitable form for a study of the global dynamics. The unperturbed system is found to contain both homoclinic and heteroclinic orbits for different parameter values. By considering the perturbation of the unperturbed Hamiltonian system, we can determine whether chaotic behavior is present.
An Improved Transfer Matrix Method for Nonlinear Rotor-Bearing Systems
Authors: Zu Jean W. , Ji Zhenyi
Published: July 2023

An improved transfer matrix method is developed to analyze rotor-bearing systems with nonlinear bearings. The rotating shaft is modeled by Timoshenko beam. The harmonic balance method is incorporated in the transfer matrix equations to obtain steady-state response of synchronous, subharmonic and superharmonic whirls.
A Mindlin Plate Element for Distributed Sensing and Control Using a Linear/Nonlinear Dynamic Coupling Strategy
Authors: Fariborzi Fariborz , Golnaraghi Farid , Heppler Glenn R.
Published: July 2023

The intention of this work is to generate a mathematical model of a plate with collocated piezoelectric actuators/sensors to be used for control purposes. The proposed control method is a linear/nonlinear dynamic coupling technique developed by the ConStruct group at the University of Waterloo.

The performance of the plate with attached layers of piezoelectric material is evaluated by a finite element model. Test results show that the application of this theory along with an appropriate choice of basis functions allows the analysis of a wide range of thicknesses. This approach avoids shear locking, and provides excellent accuracy, and convergence characteristics.
Determination of Interfacial Fracture Toughness in High Temperature Composites
Authors: Bechel V. , Sottos N. R.
Published: July 2023

Understanding the behavior of the fiber/matrix interface region over a range of temperatures is essential for designing composites that will have a high service temperature. In the current work, the interface failure sequence was observed during fiber pushout tests on two model composites (steel/epoxy and polyester/epoxy) with different Young’s moduli ratio and residual stress values. Novel photoelastic experiments were conducted on the model composites to measure the interfacial crack length versus load during the fiber push-out test. The data were used to better understand the failure mechanisms during the test and to determine the range of applicability of analytical and computational models of the test. Debonding was observed to occur from either the top or the bottom of the sample depending on the ratio of the elastic moduli of the fiber and matrix and the residual stress state. The pushout data from a polyester/epoxy system which debonded from the top was fit to a shear lag solution to obtain the fiber-matrix interfacial toughness (GIIc). The resulting interfacial toughness was then used to check the predicted debond length as a function of pushout force. The debond length calculated from the shear lag model was less than the measured debond length by a nearly constant 1.5 fiber radii which may correspond to the thickness of the surface effects region for polyester/epoxy.

In the future, the results of the model experiments will be used to understand the interfacial properties of two representative high temperature composites, SiC/Ti-Al-V and Al2O3/Ti-Al-V. A special high temperature apparatus was constructed for performing the push-out test at temperatures ranging from room temperature to 1000°C under vacuum. Performing interfacial measurements at elevated temperatures can be used to optimize interfacial performance at service temperatures and to better evaluate the effects of residual stresses and matrix ductility on fiber debonding and sliding.
Crack Deflection and Penetration Criteria for Brittle Matrix Composites
Authors: Pagano N. J.
Published: July 2023

In this work, we will consider the three most crucial mechanisms that control the behavior of unidirectional brittle matrix composites (BMC) such that they display the desired characteristics of adequate strength and damage tolerance (or toughness). Composites made with uncoated silicon carbide fibers and two different glass matrices which differ principally in their thermal expansion coefficients were made and tested in order to determine matrix crack initiation stress (Fig. 1), fiber fracture (Fig. 2), and a lower bound interface fracture toughness (Fig. 3). Furthermore, these tests provide direct evidence to examine the quality of an axisymmetric damage model (ADM) derived earlier [1, 2]. Although there was no observed damage tolerance in that both stress-strain curves were linear to failure, a stable system of (apparently) full-cell matrix cracks (Fig. 1) develops prior to ultimate failure. It is not clear if the matrix cracks have arrested prior to entering the fiber or if they have penetrated the fiber itself.
Damage in Oxidized Titanium Metal Matrix Composites
Authors: Lagoudas Dimitris C. , Xu Shouze , Miller David , Allen David H.
Published: July 2023

The oxidation effects on surface crack development of oxidized Ti 15-3 and Ti β-21S Metal Matrix Composite (MMC) unidirectional laminates under applied mechanical loading are investigated in the present study. Experimental results of surface crack development as a function of applied load are presented. An approximate mechanical model is established and a stress analysis of an oxidized laminate with surface cracks is performed. To simplify the analysis, motivated by experimental observations, a periodic distribution of surface cracks in the oxide layer is assumed. The critical value of the applied mechanical load, which is necessary for the formation of new cracks, as a function of crack density and phase transformation induced eigenstrain are studied.
Critique of Macro Flow/Damage Surface Representations for Metal Matrix Composites Using Micromechanics
Authors: Lissenden Cliff J. , Arnold Steve M.
Published: July 2023

Guidance for the formulation of robust, multiaxial, constitutive models for advanced materials is provided by addressing theoretical and experimental issues using micromechanics. The multiaxial response of metal matrix composites, depicted in terms of macro flow/damage surfaces, is predicted at room and elevated temperatures using an analytical micromechanical model that includes viscoplastic matrix response as well as fiber-matrix debonding. Macro flow/damage surfaces (i.e., debonding envelopes, matrix threshold surfaces, macro “yield” surfaces, surfaces of constant inelastic strain rate, and surfaces of constant dissipation rate) are determined for silicon carbide/titanium in three stress spaces. Residual stresses are shown to offset the centers of the flow/damage surfaces from the origin and their shape is significantly altered by debonding. The results indicate which type of flow/damage surfaces should be characterized and what loadings applied to provide the most meaningful experimental data for guiding theoretical model development and verification.