bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Semi-Analytical Solution for Responses of the Surface of an Elastic Half-Space Subjected to Vertical, Harmonic, Concentrated Forces
Authors: Hamidzadeh Hamid R. , Luo Albert C. J. 
Published: November 2021

Abstract
The dynamic response of a soil medium surface subjected to a vertical, harmonic, concentrated force is investigated. The half-space soil medium is considered to be elastic, isotropic and homogeneous. The expression of surface displacement is given analytically through a double Fourier transformation, integrals and Rayleigh functions. For numerical results of the surface response, the Modified Gaussian quadrature method is used. The in-phase and quadrature components of the displacements for any position on the surface of the unloaded half-space are illustrated for the Poisson’s ratio of 0.25 as a sample problem.
Experimental and Theoretical Analysis of a Power Transmission Belt
Authors: Pellicano Francesco , Vestroni Fabrizio , Fregolent Annalisa 
Published: November 2021

Abstract
In this paper, the effect of a pulley eccentricity on the vibration of a power transmission belt is experimentally investigated and a theoretical model is developed for validation and identification purposes. This eccentricity gives rise dangerous operating conditions for the system, especially when it excites the frequency range of the belt resonances. As expected, the system shows a hardening nonlinear behavior. Moreover, the fluctuation of the belt tension, due to the pulley eccentricity, gives rise to a parametric instability that can undergo to catastrophic failures of the structure. Experimental observations with quantitative measurements are obtained by means of a laser telemeter. Frequency response curves are drawn when the beam is harmonically excited close to the first and second linear natural frequency. A simple analytical approximation of the system response is obtained by one complex mode approximation. An asymptotic solution justifies the experimental evidence and allows the identification of the main parameters of the equation of motion. The excellent agreement between theoretical and experimental data confirms the consistency of the analytical model and the identification of the parameters.
High-Speed Passenger and Intercity Train Aerodynamic Computer Modeling
Authors: Holmes Samuel , Schroeder Martin , Toma Elton 
Published: November 2021

Abstract
With the onset of high-speed passenger train service in the United States, the Federal Railroad Administration (FRA) and railroad agencies are concerned with the aerodynamic effects these trains will have on lightweight freight equipment, such as empty double stack container cars. This paper presents the results of a research project that evaluated this interaction. In this study we conducted a series of computational fluid dynamic (CDF) calculations to characterize the aerodynamic loads on a container consist passed by a high-speed train. A train motion simulation program was used to determine resultant motion and risk of overturning or derailment of the container consist. Numerous cases were studied in which train speed and wind speed and direction were varied.
Identification and Prediction of Frame Structure Dynamics by Spatial Matrix Identification Method
Authors: Okuma Masaaki , Heylen Ward , Matsuoka Hisayoshi , Sas Paul 
Published: November 2021

Abstract
This paper presents the result of using an experimental spatial matrix identification method to predict the dynamics of a frame structure under a different boundary condition. The single-input-multiple-output frequency response functions of the test structure under the free-free boundary condition are measured by hammer testing. Using the FRFs, a set of spatial matrices is determined to represent its structural dynamic characteristics by the method. Then, using the identified spatial matrices, the dynamic characteristics of the test structure under the boundary condition of clamping 4 points is predicted. The prediction is practically accurate. The result of the prediction demonstrates that the spatial matrices identified by the method can be used for structural modification and substructure synthesis in the field of computer aided mechanical engineering.
A Determination of Biophysical Parameters Related to Freezing of an ELT-3 Cell Line
Authors: Berrada Marwane S. , Bischof John C. 
Published: November 2021

Abstract
This study investigates two destructive biophysical mechanisms during freezing (extensive dehydration and intracellular ice formation) at the cellular level in the rodent ELT-3 uterine fibroid cell-line. The osmotically inactive volume fraction (Vb) of ELT-3 cells was approximated to 0.35 of the initial isotonic cell volume (Vo). The water transport characteristics of this cell-line are such that ELT-3 cells are highly permeable with a strong ability to lose water even at low subzero temperatures. The hydraulic reference permeability, Lpg and activation energy, Elp associated with Lp were found to be 0.13 (μm/min.atm) and 19.0 (kcal/mole) [R2 = 0.86] respectively. Intracellular Ice Formation (IIF) occurs at lower temperatures than many cell-types (i.e. TIIF 50% below −15°C) at cooling rates &gt; 25 °C/min. Darkening IIF, which was assumed to occur by Surface Catalyzed Nucleation (SCN), is governed by kinetic Ωo and thermodynamic κo biophysical parameters, which were found to be 6.1×108(m2.s)−1 and 5.3×109(K5) [R2 = 0.94] respectively. At a cooling rate of 100°C/min, twitching IIF (non-darkening IIF) was observed. Viability data from a separate study (Bischof et. al., 2000) indicated that at cooling rates ≤ 1°C/min and ≥ 50°C/min with an end-temperature of −20°C, extensive damage to cells was observed. The current biophysical study shows that extensive dehydration occurs at 1°C/min while substantial IIF (77%) occurs at 50 °C/min. This data suggests that while biophysics can explain some of the destruction occurring at the investigated temperatures, other effects or mechanisms may be playing a role at lower end-temperatures.
H∞ Optimization of Fixed Structure Controllers
Authors: Ibaraki Soichi , Tomizuka Masayoshi 
Published: November 2021

Abstract
In this paper, the H∞ optimization problem of fixed structure linear controllers is considered. Applications of the problem include tuning of SISO (Single-Input Single-Output) PID (Proportional plus Integral plus Derivative) controller gains. The proposed algorithm starts with transformation of the original problems into a static output feedback controller synthesis problem, which does not impose any constraints on the controller structure except for its order. Unlike the full-order H∞ controller synthesis case, the H∞ optimization problem of static output feedback controllers cannot be reparameterized as a convex optimization problem. The cone complementarity linearization algorithm is used to overcome the nonconvexity problem due to the constraint on the controller order. The proposed algorithm is applied to the design of a SISO PID controller for head positioning of a magnetic hard disk drive.
Modeling and Coordinated Control of an Earthmoving Vehicle Powertrain
Authors: Prasetiawan Eko , Zhang Rong , Alleyne Andrew 
Published: November 2021

Abstract
An earthmoving vehicle powertrain is modeled as a MIMO hydrostatic system. Its control inputs include the engine throttle, an electro-hydraulic pump displacement and flow valve commands. These inputs offer a great control freedom but need to be coordinated. As a starting point for the ultimate MIMO control, a coordinated MISO controller for one of the load nodes is designed by using an LQG technique. Modeling and control design are accomplished and validated by both first principles and experimental data. The experimental data are obtained upon an Earthmoving Vehicle Power-train Simulator (EVPS) at the University of Illinois. The paper details the utilization of this “hardware-in-the-loop” testbed in investigating generic power-optimization problems for hydrostatic transmissions. Simulation results as well as experimental data are presented.
Lapping Control of Hard Disk Drive Heads: Part II—Control
Authors: Mei Youping , Stelson Kim A. 
Published: November 2021

Abstract
Using numerical modeling as a tool, the pressure dynamics of bar lapping is identified. The process model is constructed based on the pressure dynamics and the Preston model. A controller is then designed using a trajectory following formulation. Simulation of the controller designed as such shows that it is robust to parameter uncertainties. This controller is implemented on a Seagate lapping system. Experiment results show that the proposed method is less sensitive to the quality of the preparation processes. However, the gains should be appropriately adjusted for optimal performance. With good preparation processes and appropriate gains, performance of the two methods are statistically comparable. Otherwise, the proposed method performs better. The proposed method is inferior to the existing method only when its gains are improperly adjusted.
Integration of Geometric and Mechanistic Models of NC Machining Into an Open-Architecture Machine Tool Controller
Authors: Jerard Robert B. , Fussell Barry K. , Ercan Mustafa T. , Hemmett Jeffrey G. 
Published: November 2021

Abstract
A great deal of research has been done during the last twenty years on the modeling and control of NC machining. Despite the promise of substantial productivity improvements these methods are sparsely used outside their academic birthplaces. We believe that Open-Architecture Controllers (OAC) are the key to unlocking this unfulfilled potential. We describe the implementation of novel methods for feedrate optimization which utilize a commercially available OAC. In this paper an example is given of how substantial improvements in machining processes can be achieved by implementing geometric and mechanistic models of the cutting process on an OAC. These benefits should provide motivation for a more universal adoption of OACs.
Real-Time Detection of Wheel and Work-Piece Contact/Release in Reciprocating Surface Grinding
Authors: Razavi H. Ali , Kurfess Thomas R. 
Published: November 2021

Abstract
In this paper a signal-processing algorithm to detect wheel and work-piece contact/release is introduced. Simulation is used to demonstrate the approach followed by a series of experiments for real-time validation. Although, the method is implemented on a special application, there exists potential for other applications.
An Energy-Enhanced Design of Experiments Method
Authors: Christensen Bjorn G. , Ferris John B. , Stein Jeffrey L. 
Published: November 2021

Abstract
Computer models of complex mechanical systems are being used more frequently and effectively due to ever increasing computing power. These models have improved the design process by allowing designers to create virtual prototypes of systems. Computer models permit iterative designs, thereby allowing the designer to run hundreds of simulations in the time it would take to make one physical model and test it. This ease of iteration has made design of experiments (DOE) analyses easy to carry out on the computer models. A DOE analysis provides excellent information regarding the specific output function being examined, but may overlook some of the global effects that these changes may have on the system. A new design tool is developed in this work that addresses this deficiency. The new method greatly improves upon existing design tools such as DOE. Specifically, the new method augments a traditional DOE study with an Activity study, which focuses on the energy flow in the system and provides a larger picture of the system dynamics. Instead of using only a DOE analysis to determine which elements’ properties should be changed, the Activity of the elements is also considered. This helps prevent altering a parameter or set of parameters to achieve a desired response at the expense of other unforeseen results. This idea is demonstrated by investigating the issue of designing a vehicle for improved ride quality. A simple quarter car model is used so that the results can be clearly seen. The example shows that design changes based on a DOE analysis alone can improve the ride quality, but also can alter other system responses significantly. When an Activity analysis is combined with the DOE study, the ride quality is improved, but the effects on other aspects of the system are greatly reduced. Augmentation of DOE with Activity allows a specific design goal to be achieved and also provides global information about the system. This allows the engineer to make informed decisions about the effects of changes on the system.
The Development of a Split-Tube Flexure
Authors: Goldfarb Michael , Speich John E. 
Published: November 2021

Abstract
This paper describes the design of a flexure joint, called the split-tube flexure, which can provide a considerably larger range of motion and significantly better multi-axis revolute joint characteristics than a conventional beam-type flexure. Specifically, the flexure joint contrasts the torsional compliance of a thin-walled open-section member with its bending rigidity to produce kinematically well-behaved revolute motion. The joint proves particularly useful in applications requiring kinematically well-behaved large motions, such as in robot manipulators.
Robust Dynamic Locomotion Through Feedforward-Preflex Interaction
Authors: Cham Jorge G. , Bailey Sean A. , Cutkosky Mark R. 
Published: November 2021

Abstract
Unlike most legged robotic systems built to date, even simple animals have the ability to quickly and robustly traverse through rough terrain and over large obstacles and gaps. Recent evidence from insect physiology research indicates that arthropods achieve this fast robust locomotion largely without relying on sensory feedback or reflex response. Instead, locomotion is the result of the interaction between a basic feedforward motor pattern and the visco-elastic properties of the mechanical system, termed “preflexes.” In this paper, we consider the implications of this control hypothesis for the design of small running robots for uncertain environments. We present working prototypes that show how robust dynamic locomotion can be achieved without the use of sensory feedback. We then discuss modeling approaches for these kinds of systems and present results from simulations of representative models.
A High-Bandwidth Force-Controlled Haptic Interface
Authors: Lee Christopher D. , Lawrence Dale A. , Pao Lucy Y. 
Published: November 2021

Abstract
The design and control of a 5 degree-of-freedom (DOF) haptic interface that provides accurate rendering of forces as well as a large range of motion is presented. We review a number of design approaches that have been considered in other haptic interfaces and the reasons for choosing a parallel mechanism for our design. The choice and motivation for the actuators, sensors, and materials used are also discussed. High bandwidth transmission of forces is achieved through a force control loop in each degree of freedom. Details of the single actuator control design process and the robustness of the controllers are also overviewed. The resulting interface is able to provide a workspace of about 40 cm in translation in 3 DOF and about ±60 degrees in 2 DOF of angular motion, and the force controllers have closed-loop bandwidths of about 175 Hz.
Nonlinear Crack Growth Monitoring
Authors: Welch Donald E. , Hively Lee M. , Holdaway Ray F. 
Published: November 2021

Abstract
Structures subject to crack growth spend 90–95% of their lifetime in nucleation of very tiny flaws into measurable crack sizes. Due to the large variation in initial flaw sizes and the mathematics of flaw growth, the fatigue lifetimes, even of high-quality structures, can vary by a factor of as much as 10 to 20 even in a small fleet. This large variation in fatigue lifetimes leads to conservative statistics, which often prompts the premature retirement or overhaul of structures, since they focus on the weakest members of the fleet, while the remainder of the fleet is sound.
In the past two years, Oak Ridge National Laboratory (ORNL) has developed a new Griffith energy-based technique that can provide useful warning of the impending failure of a structure due to end-of-life crack propagation. This technique has been demonstrated by test and analysis in fiberglass composite for tension-tension fatigue.
High Speed Crash Barrier Investigation Using Simulation
Authors: Reid John D. , Faller Ronald K. , Sicking Dean L. 
Published: November 2021

Abstract
Auto racing has become one of the most popular sporting venues in the United States. For these events, vehicles typically travel around oval tracks at extremely high speeds, in some cases in excess of 365 km/h. At these higher speeds, these vehicles may be involved in multi-car collisions or impacts with the exterior rigid walls, potentially resulting in serious driver injuries or fatalities. Although infrequent, serious harm has also occurred to spectators as flying vehicle debris has passed over protective fencing. As a result of these accidents, researchers at the Midwest Roadside Safety Facility, in cooperation with the Indy Racing League, Indianapolis Motor Speedway, and Kestrel Advisors, Inc., have been investigating and developing several energy-absorbing barrier concepts that would provide increased track safety. Two concepts — one using HDPE plates and one using crushable foam — are described herein. Preliminary results from the computer simulation effort show great potential for increasing the safety of race track barriers.
A Sub-System Test Methodology for Simulating EEVC Side Impact
Authors: Aekbote Krishnakanth , Sundararajan Srinivasan , Prater Joseph A. , Abramczyk Joe E. 
Published: November 2021

Abstract
A sled based test method for simulating full-scale EEVC (European) side impact crash test is described in this paper. Both the dummy (Eurosid-1) and vehicle structural responses were simulated, and validated with the full-scale crash tests. The effect of various structural configurations such as foam filled structures, material changes, rocker and b-pillar reinforcements, advanced door design concepts, on vehicle performance can be evaluated using this methodology at the early stages of design. In this approach, an actual EEVC honeycomb barrier and a vehicle body-in-white with doors were used. The under-hood components (engine, transmission, radiator, etc.), tires, and the front/rear suspensions were not included in the vehicle assembly, but they were replaced by lumped masses (by adding weight) in the front and rear of the vehicle, to maintain the overall vehicle weight. The vehicle was mounted on the sled by means of a supporting frame at the front/rear suspension attachments, and was allowed to translate in the impact direction only. At the start of the simulation, an instrumented Eurosid-1 dummy was seated inside the vehicle, while maintaining the same h-point location, chest angle, and door-to-dummy lateral distance, as in a full-scale crash test. The EEVC honeycomb barrier was mounted on another sled, and care was taken to ensure that weight, and the relative impact location to the vehicle, was maintained the same as in full-scale crash test. The Barrier impacted the stationary vehicle at an initial velocity of approx. 30 mph. The MDB and the vehicle were allowed to slide for about 20 inches from contact, before they were brought to rest. Accelerometers were mounted on the door inner sheet metal and b-pillar, rocker, seat cross-members, seats, and non-struck side rocker. The Barrier was instrumented with six load cells to monitor the impact force at different sections, and an accelerometer for deceleration measurement. The dummy, vehicle, and the Barrier responses showed good correlation when compared to full-scale crash tests. The test methodology was also used in assessing the performance/crashworthiness of various sub-system designs of the side structure (A-pillar, B-pillar, door, rocker, seat cross-members, etc.) of a passenger car. This paper concerns itself with the development and validation of the test methodology only, as the study of various side structure designs and evaluations are beyond the scope of this paper.
How Cell Shape Affects the Stresses in a Cell Sheet
Authors: Brodland G. W. , Veldhuis Jim H. , Chen Daniel I-Li 
Published: November 2021

Abstract
Computer simulations and analytical mechanics are used to investigate the mechanics of cell sheets. The simulations are based on a recent finite element formulation [1] in which each cell is modeled using multiple finite elements, and cells can rearrange. Sheet stresses calculated using an analytical expression based on average cell shape are found to agree well with those calculated in the finite element simulations. This is an important step towards the development of constitutive equations to describe real cell sheets.
Finite Element Model of the Human Knee Joint to Study Tibio-Femoral Contact Mechanics
Authors: Donahue Tammy Haut , Hull Maury L. , Rashid Mark M. , Jacobs Christopher R. 
Published: November 2021

Abstract
A finite element model of the tibio-femoral joint in the human knee was created using a new technique for developing accurate solid models of soft tissues (i.e. cartilage and menisci). The model was used to demonstrate that constraining rotational degrees of freedom other than flexion/extension when the joint is loaded in compression markedly affects the load distribution between the medial and lateral sides of the joint. The model also was used to validate the assumption that the bones can be treated as rigid.
Normal Cartilage Thickness and Osteoarthritic Wear Patterns of the Human CMC Joint
Authors: Koff Matthew F. , Cohen Zohara A. , Ugwonali Obinwanne F. C. , Balaguer Eric J. , Ateshian Gerard A. , Mow Van C. 
Published: November 2021

Abstract
Cartilage thickness maps of the trapezium and metacarpal of the human thumb carpometacarpal (CMC) joint were determined from 51 hands. Specimens were divided into 3 groups based on visual staging of the articular cartilage surfaces for osteoarthritis (OA), and average thickness maps were created for both surfaces within each group. Statistical analyses demonstrated that in advanced OA, cartilage on the trapezium thins on the volar and dorso-radial regions, while the metacarpal exhibits thinning on its volar aspect.
Towards Reliable Thermal Spray Coatings: An Integrated Approach
Authors: Sampath Sanjay 
Published: November 2021

Abstract
Thermal sprayed coatings are used extensively in engineering components for a variety of protective coating applications. Thermal spraying is a highly dynamic process resulting from rapid heating /accelerating of powder particles in a flame, followed by impact and rapid solidification of the droplets (splats). A splat resulting from the flattening of an individual droplet is the basic building block (unit cell) of the thermal sprayed microstructure. Phase and microstructure of the splats (intrinsic) and the integration of the splats (extrinsic) are both affected by processing condition and the properties of a plasma sprayed deposit are directly related to this complex anisotropic microstructure. These affect both performance and reliability of sprayed surfaces.