bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tensegrity Prisms as Adaptive Structures
Authors: Oppenheim Irving J. , Williams William O. 
Published: March 2022

Abstract
Tensegrity prisms are three-dimensional self-stressing cable systems with a relatively small number of disjoint compression members. Invented by Buckminster Fuller, they form novel structural geometries and constitute a class of mechanisms that have not been previously studied in depth. They have a number of seemingly advantageous properties — they are self-erecting, in that tensioning the final cable transforms them from a compact group of members into a large three-dimensional volume, and they are predominately tension systems. However, they have a number of properties that make them seemingly inappropriate for use — they are not conventionally rigid, they exist only under specific conditions of geometry with a corresponding prestress state, and when they exist the governing equations include singular (non-invertible) matrices. The mathematics of tensegrity geometry, statics, and kinematics have not been fully formulated, and such mathematical results must be developed and assembled before applications can be undertaken. This paper describes the physical behavior of a basic family of tensegrity prisms, presents the most useful available mathematical results, and outlines observations from an experimental study.
Probabilistic Methods for Performance Evaluation of Actively Controlled Structures
Authors: Akpan Unyime O. , Orisamolu I. R. (Wally) 
Published: March 2022

Abstract
Active Structures have significant practical applications in areas such as vibration, noise and shape control. In recent times, several studies on modeling of the response and control of these structural systems have been undertaken. Most of these studies use deterministic procedures for designing the required active control systems, with the underlying assumption that the design parameters are accurately known. However, for most practical situations, the values of the design parameters are not known exactly and must therefore be treated as random variables. Parametric uncertainties can degrade the performance of an otherwise well designed control system, sometimes leading to instability. In this paper probabilistic models for evaluating the performance of actively controlled structures is presented. A closed loop damping ratio formulation is proposed for the determination of the probability of instability for such structures in the presence of real parameter uncertainties. Furthermore, a probabilistic model for evaluating the performance robustness of actively controlled systems in terms of margin of stability is developed. Advanced probabilistic reliability analysis algorithms namely the first order reliability methods (FORM) and the second order reliability methods (SORM) are used for the estimation of robustness. A comparison of estimates of the probabilistic stability robustness from the proposed closed loop damping ratio formulation and the eigenvalue model which has been employed in recent studies (Field, 1996; Spencer 1992) is undertaken. It is shown that both procedures yield the same result. However, the novel technique has the added advantage of computational efficiency for FORM and SORM applications. Furthermore, it is shown that for the class of controllers considered in this study, robustness estimates from FORM is adequate for meaningful engineering decisions. Sensitivities of the controlled structure stability robustness to uncertainties in model parameters is evaluated using the novel approach.
Single Actuator and Multi-Mode Acceleration Feedback Control
Authors: Bayon de Noyer Maxime P. , Hanagud Sathya V. 
Published: March 2022

Abstract
The objective of the paper is to develop a vibration control design procedure that uses a single actuator to suppress vibrations in many structural modes simultaneously by using acceleration feedback controllers. In this paper, a new technique, based on the cross-over point design, has been developed to compute the compensator parameters to achieve the objective. This new technique has been validated by both experimental studies and simulation studies. The new design procedure has also been compared experimentally and analytically to previous design of acceleration feedback controllers by using the critically damped compensators. Then, experimental and analytical investigations are directed to control more than one mode with a single actuator. This is demonstrated by using piezoceramic wafer actuators and an accelerometer sensor on a beam structure.
Both Fall Direction and Muscle Activation Level Influence Likelihood of Hip Fracture in Falls
Authors: Sabick Michelle B. , Goel Vijay K. , Hay James G. , Banks Scott A. 
Published: March 2022

Abstract
An optimal body position at impact increased the force needed to cause structural yielding in the femur during a fall by up to 280%. Falls which resulted in impact on the posterolateral aspect of the greater trochanter or buttocks were the most likely to result in hip fracture. Decreasing the muscular activation level from tense to relaxed led to a 6% decrease in peak impact force. We recommend that, to be most effective, hip pads be placed on the posterolateral aspect of the greater trochanter. In addition, seniors at risk of hip fracture should be taught to relax their bodies once the onset of a fall is detected, if possible. Both interventions are effective in reducing the peak force experienced at impact.
A Transducer for the Dynamic Measurement of Neural-Space Occlusion in the Spine
Authors: Raynak Geoffrey C. , Nuckley David J. , Ching Randal P. , Tencer Allan F. 
Published: March 2022

Abstract
Spinal injury can be the most devastating of all orthopaedic trauma because of the critical role the spine plays in protecting the neural elements. Geometric changes to the bony foramen designed to accommodate these elements are likely the best predictors of potential neurologic injury [1,2]. Previous experiments have demonstrated poor correlation between post-traumatic and dynamic measurements of spinal canal occlusion taken during impact — with peak transient occlusion levels typically greater than those observed post-injury [3]. Others have hypothesized that mechanical trauma may trigger a cascading sequence of events leading to neurologic damage [4]. Hence, in contrast to post-traumatic measurements, we believe that dynamic measurement of neural-space occlusion during injury may provide better insight into the initiation of these events.
The Influence of Surfactant Physicochemical Properties on Pulmonary Interfacial Flow Analogues
Authors: Gaver Donald P. , Krueger Melissa A. , Ghadiali Samir N. 
Published: March 2022

Abstract
Many of the lung’s mechanical properties are influenced by pulmonary surfactant physicochemical characteristics. Pulmonary surfactant is a complex lipid-protein mixture formed in the type II alveolar cells and secreted into the alveolar subphase [1]. These substances reduce the surface tension at the air-liquid interface of the lining fluid that coats the interior of the lung. At sufficiently high concentrations, pulmonary surfactant reduces the surface tension to near zero and. in the process, stabilizes the alveoli and small airways [2–4].
Effect of Dynamic Glutaraldehyde Crosslinking on the Biomechanics of Pericardium Xenograft Tissue
Authors: Duncan Anthony C. , Boughner Derek 
Published: March 2022

Abstract
Bovine pericardium was fixed under dynamic conditions, low pressures (&lt; 4mmHg) and low vibration rates (1.2 Hz) in a 0.5 % glutaraldehyde solution. After fixation, tensile testing (i.e. relaxation and stress-strain curves) was performed at low (3 mm/s) and high extension rates similar to physiological rates (30 mm/s i.e. 15 000% min−1).
Molecular Mechanisms of Monocyte Adhesion to Cytokine Stimulated Endothelial Cells Under Physiological Flow Conditions
Authors: Kukreti Sharad , McIntire Larry V. , Smith C. Wayne 
Published: March 2022

Abstract
This study investigates the underlying mechansisms of monocyte adhesion to both short term (IL-1β, 4 hr) and long term (IL-4, 24 hr) activated endothelial cells. At a wall shear stress of 2 dynes/cm2, monocytes appear to use multiple pathways for primary and secondary adhesion to IL-1β, 4 hr stimulated endothelial cells. However, on IL-4 24 hr stimulated HUVECs, VLA-4/VCAM-1 was the dominant mechanism for monocyte adhesion. Upon additional histamine exposure of IL-4, 24 hr treated endothelial cells, both P-selectin and VLA-4 were involved and had to blocked simultaneously to abolish monocyte adhesion. A combination of IL-1+IL-4 (24 hr) treatment resulted in a complete loss of the primary adhesive mechanism under flow conditions whereas secondary adhesion remained intact as indicated by static experiments.
Computational Mechanics of Blood Flow and Arterial Wall Interactions: Effect of Wall Mechanical Properties
Authors: Yamaguchi Takami , Kobayashi Takuji 
Published: March 2022

Abstract
The whole atherogenetic process should be considered as a net result of biological, chemical and mechanical interactions between the blood flow and the arterial wall. As common in all three types of interactions, they have several different time scales. Even in the context of wall mechanical responses, we should distinguish very short term, in other words, pure mechanical responses from intermediate and long term responses involving chemical and biological processes, which are results of an accumulation of the former. In our previous reports[1–2], the fluid motion and the wall motion in models of the arterial stenosis and the abdominal aneurysm with thick deformable walls was computed. In the present study, we are interested in some intermediate process in which the arterial wall changes its mechanical properties, and computed the fluid-wall interactions with different stiffness of the lesion.
Experimental Measurement of Cartilage Interstitial Fluid Pressurization Under Confined Compression Stress-Relaxation
Authors: Soltz Michael A. , Ateshian Gerard A. 
Published: March 2022

Abstract
Articular cartilage is an excellent bearing material able to withstand high loading pressures and experience little wear for nearly 70 to 80 years. Many investigators have suggested that these remarkable properties stem partly from the pressurization of cartilage interstitial fluid during joint loading (e.g., [1,8]). Indeed, theoretical analyses of biphasic or poroelastic cartilage contact have demonstrated that upward of 90% of the contact load may be supported by interstitial fluid pressurization (e.g., [1,6,7]). However, direct experimental verification of these theoretical findings has been difficult to achieve and few studies have reported direct measurements of cartilage interstitial fluid pressure [2,3]. Thus, the objectives of this study are to measure both the fluid pressure and total load acting at the cartilage contact interface, to determine the fraction of load supported by interstitial fluid pressurization as a function of time [3], and to compare this result with the biphasic theory for cartilage [9]. These objectives are achieved by testing cartilage cylindrical plugs under confined compression stress-relaxation.
Simulating Soft Tissue With a Tactile Shape Display
Authors: Pawluk Dianne T. V. , Peine William J. , Wellman Parris S. , Howe Robert D. 
Published: March 2022

Abstract
One of a surgeon’s most important tools is a highly developed sense of touch. Surgeons rely on sensations from the fingertips to guide manipulation and to perceive a wide variety of anatomical structures and pathologies. One important property used to assess the health of organs and tissues is compliance, which surgeons normally obtain by squeezing or indenting with their fingers.
Accelerometric/Encoder System and Method to Determine Kinematic Parameters During Stationary Holonomic Exercise
Authors: Figueroa Fernando , Shackelford Linda , Haw Chee Wee 
Published: March 2022

Abstract
A novel method and system to determine angular accelerations, angular velocities, and angular positions of the thigh and calf has been developed. Measurements are taken during stationary bicycle exercise. The approach considers only two dimensional motion (sagital plain). The kinematic parameters are obtained based on acceleration measurements from two two-dimmensional accelerometers fixed to each member (calf and thigh). The method is unique in that it does not perform integration to arrive to angular positions, thus avoiding buildup of errors associated with integration. Tests were performed using simulated data. An error analysis was performed. The system’s expected maximum error is approximately 2° in the calf position for a bicycling speed of one cycle per second.
Friction Properties at Polyethylene-Metal Interface in Total Joint Arthroplasty
Authors: Hashemi A. , Dammak M. , Shirazi-Adl A. , Zukor D. J. 
Published: March 2022

Abstract
Ultra high molecular weight polyethylene (UHMWPE) is currently used in artificial joints as the best polymer for bearing against metallic counterparts. It has a low coefficient of friction, a good resistance against wear, and a high toughness. In recent years however, the suitability of this material has been questioned due to the association between implant loosening by osteolysis in the joint vicinity and polyethylene debris. Friction characteristics at polyethylene-prosthesis articular interface influence the state of stress at and around articular regions and consequently the extent of surface damage and wear of both materials in contact. In this investigation, following our earlier bone-implant friction studies [1–3], uni- and bi-directional friction properties of polyethylene-metal interface are measured under different contact pressures and two conditions of wet and dry.
A Relationship Between Frontal Plane Geometry and Contact Stress Distribution in a UHMWPE of a TKR Component
Authors: Natarajan R. N. , Beard B. J. , Andriacchi T. P. 
Published: March 2022

Abstract
Permanent deformation in the Ultra High Molecular Weight Polyethylene tibial component has been reported in more than 60% of retrieved components (T.Wright 1968). Under conditions of elastic and plastic deformation, the femoral condyle can penetrate into the polyethylene component such that the smaller contact radii existing at the edges of the primary contact radii in the frontal plane can come into contact with the polyethylene surface (Figure 1). Under these conditions Hertzian contact theory or finite element models that do not include both elastic and plastic deformation would not apply. The aim of this study was (1) to calculate the penetration of the femoral condyle into the polyethylene component as a function of the frontal plane radii, and (2) to predict the altered contact stress distribution in the polyethylene component under conditions where penetration exceeds the primary bearing surface.
Touch Feedback Using Binary Tactor Displays: Unexpected Results and Insights
Authors: Murray Anne M. , Klatzky Roberta L. , Shimoga Karun B. , Khosla Pradeep K. 
Published: March 2022

Abstract
Most researchers support the idea that touch feedback should enhance a human operator’s ability to manipulate remote or virtual objects. In this paper, we discuss an experiment we conducted to demonstrate quantitatively the usefulness of touch feedback for a pick-and-place manipulation task in a dexterous telemanipulation environment. We also examine how the actuation threshold for our binary, low-frequency vibrotactile touch feedback system affects an operator’s performance.
The results are not what we originally expected. When direct visual feedback was provided, there was no marked improvement in task performance as measured by task completion time, number of errors committed, mean grip force, and maximum grip force when using binary touch feedback. Analysis suggests that when a human operator had good visual confirmation of the grasp, as the subjects did in this experiment, the visual feedback dominated the binary touch feedback. We believe this dominance was due, in part, to the characteristics of the touch feedback: it was binary, providing less information than the visual feedback, and there were longer delays in receiving the touch stimuli than the visual information.
Designing Haptic Interfaces for Teleoperational and Virtual Environments: Should Spatially Distributed Forces Be Displayed to the Fingertip?
Authors: Lederman Susan J. , Klatzky Roberta L. 
Published: March 2022

Abstract
The current study evaluated the role of spatially distributed fingertip forces in the performance of a set of sensory (force detection, spatial acuity, vibrotactile detection) and perceptual (roughness perception, 2D edge orientation, and 3D lump detection via fingertip palpation) tasks. Vision was not permitted. Each task was performed with and without spatially distributed, fingertip-force information. The elimination of such spatial cues substantially impaired performance of all but the vibrotactile-detection and roughness-perception tasks. Despite some decline in roughness perception, subjects were still able to perform related tasks reasonably well. The results offer scientific support for incorporating spatially distributed, fingertip force information in the design of dextrous haptic interfaces.
The Programming of a Telemanipulator With the Force-Cube
Authors: Schaude Horst F. , Dillmann Rüdiger 
Published: March 2022

Abstract
While programming a telemanipulator the operator often uses special input devices to generate trajectories, which are to difficult for automatic planers. Though the trajectories are evaluated by a simulation and shown on a graphical animation, it is much faster to give the operator direct haptic feedback if a collision will occur while executing the trajectory. To combine the haptic feedback with an intuitive input device, we have developed the ForceCube. The input parameters are separated in three translational and three rotational values. They are matched on three orthogonal sides of a cube in such way, that their axes correspond to their counterparts in the real word. Each of the axes can be blocked in one direction. With this feature it is possible to move the manipulator with contact in one direction and without any constraints in the other directions. The ForceCube is integrated in the teleoperation system TelOS developed at the Institute for Real-Time Computing and Robotics.
Vibrotactile Feedback for Industrial Telemanipulators
Authors: Dennerlein Jack Tigh , Millman Paul A. , Howe Robert D. 
Published: March 2022

Abstract
Industrial applications of haptic feedback systems that add dexterity to telemanipulators have been limited due to their complexity, low reliability, and high cost. A promising and attractive alternative technology for industry is vibrotactile feedback. These systems are simple and can be added at low cost to existing telerobotic systems to provide robust contact information. We have developed a single channel prototype vibrotactile sensor and display system for a high capacity deep sea remote manipulator, the Schilling Robotic Systems TITAN-II. The vibration sensor consists of a pair of steel plates machined to fit inside the gripper jaws. Embedded between the plates are piezoelectric film strips molded into a rugged silicone rubber layer. Impact and frequency response tests indicate the sensor is durable to the extreme loading and sensitive to a large range of vibration frequencies of the industrial setting. Tests of the prototype system on the TITAN-II again proved the sensor to be rugged and durable while also being sensitive. In informal tests, operators found the system enhanced operation of the robot.
A Holonomic Omnidirectional Wheelchair With Augmented Stability Using a Reconfigurable Footprint Mechanism
Authors: Wada Masayoshi , Asada Haruhiko H. 
Published: March 2022

Abstract
A novel wheelchair moving platform with varying wheelbase and tread is designed and built. The width of wheelchairs for residential use is limited to the width of standard doorways which the wheelchair must go through. Yet the wheelchair must have an enough stability margin although the patient’s mass centroid may significantly change. In this paper, a new mechanism for varying the footprint of a four-wheeled omnidirectional wheelchair is presented. The chair is mounted on a moving platform with four ball wheels allowing for holonomic, omnidirectional motion. Two pairs of ball wheels at the diagonal positions of the chassis are fixed, respectively, to two beams that intersect at the pivotal point in the middle. The angle between the two beams crossing at the pivotal point is varied actively so that the ratio of the wheelbase to the tread can be varied. Four independent servomotors driving the four ball wheels allow the wheelchair to move along three axes, i.e. x, y, and ϕ, and change the footprint at the same time. The footprint configuration is controlled based on the measurement of the mass centroid position in such a way that the mass centroid can be kept within the footprint at all times. First the concept of the reconfigurable footprint mechanism is described, and its kinematic and static behavior is analyzed, followed by the control design for augmenting the vehicle stability. A prototype wheelchair platform is designed, built, and tested.
A Two Dimensional Dynamic Model Simulation of Human Knee Joint
Authors: Türkay O. S. , Küçük H. , Akgün I. , Aydingöz Ö. , Aşkar G. Altay , Dökmeci M. C. 
Published: March 2022

Abstract
A two dimensional dynamic model of the human knee joint is improved by employing more realistic bone profiles and ligament models. The knee model consists of a fixed rigid femur and a moving rigid tibia connected by the fiber tissues. The two articulating surfaces are represented by polynomial equations. The knee joint ligaments are modeled as nonlinear springs with a linear-parabolic operating region which is considered to be a more representative model. The nonlinear differential equations of motion constrained by geometrical nonlinear algebraic equations are solved numerically to simulate the knee dynamics under external pulse forcing. The flexion and extension motions, and the effects of pulse direction and ligaments insertion coordinates on the ligaments tension and point contact forces are discussed.
Robust Control of a Differentially Steered Wheeled Mobile Robot
Authors: Zhang Yulin , Hong Daehie , Velinsky Steven A. 
Published: March 2022

Abstract
This paper presents a robust control algorithm for exponentially stable tracking control of a differentially steered Wheeled Mobile Robot (WMR). The exponential tracking property is guaranteed with kinematic uncertainties, such as wheel slippage and radius errors. The control algorithm has been designed for use in a WMR which is being specifically developed for applications in highway maintenance and construction. For such applications, the uncertainties arise due to the road surface conditions and the high loads encountered (both inertial and tool forces). However, the system under development is equipped with a two dimensional cable extension transducer which has been proven to be a rugged and accurate position measurement system (Hong, et al., 1995), so that the robust control algorithm developed is suitable and ensures good tracking performance. The algorithm is applicable to any differentially steered WMRs provided that accurate position measurement is available. The efficiency of the robust control algorithm is illustrated with numerical simulations.