bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Model Based Approach for Efficient Segmentation of Knee Cartilage From MR Image Data
Authors: Alexander Eugene J. , Andriacchi Thomas P. 
Published: November 2021

Abstract
A novel algorithm was developed to facilitate segmentation of the articular cartilage of the knee from magnetic resonance (MR) image data. The new approach uses a model of the bone and cartilage elements of the knee as a template. The operator initializes the template by aligning certain bony anatomic landmarks. The inner cartilage surface (ICS) is determined through a standard seed growing segmentation approach; the bone elements of the template are then fit to the ICS through an elastic registration technique. The deformation fields thus obtained are subsequently applied to the appropriate cartilage templates. The deformed templates and ICS normals, in conjunction with a gaussian probability distribution function and the subject image data, are used to produce the final estimate of the cartilage surfaces.
The Influence of Depth-Dependent Inhomogeneity on the Contact Response of Human Patellar Cartilage
Authors: Krishnan Ramaswamy , Park Seonghun , Soltz Michael A. , Pawluk Robert J. , Ateshian Gerard A. 
Published: November 2021

Abstract
One of the aims of modeling articular cartilage is to determine its ability to sustain its physiological loading environment and the mechanisms by which this functional response might be compromised. It has long been hypothesized that excessive stresses in cartilage might initiate osteoarthritis, thus a determination of the state of stress within the tissue has been an important objective. It has also been hypothesized that the interstitial water of articular cartilage plays a primary role in producing low friction and wear as well as shielding the collagen-proteoglycan solid matrix from a significant portion of the loads applied across joints [1]. Furthermore, cartilage exhibits inhomogeneity through its depth, both in its tensile and compressive properties, though the significance of this inhomogeneity on the functional response of cartilage remains to be elucidated. The specific aims of the current study are to (a) experimentally determine the depth-dependent tensile and compressive properties of human patellar articular cartilage; (b) determine the response of cartilage to loading under a contact configuration using finite element models which employ these experimentally determined material properties; and (c) compare the response of the tissue to a hypothetical homogeneous distribution of material properties through the depth. The first hypothesis is that the inhomogeneity of articular cartilage acts to maximize the interstitial fluid load support at the articular surface. The second hypothesis is that the depth-dependent inhomogeneous distribution of cartilage properties acts to produce a more homogeneous state of stress than would be achieved had the properties been constant through the depth. This study extends our previous contact analyses of homogeneous cartilage layers [2,3].
The Strain-Softening of Bovine Articular Cartilage Under Infinitesimal Deformation in Unconfined Compression
Authors: Wang Christopher C.-B. , Chahine Nadeen O. , Kelly Terri-Ann N. , Lai W. Michael , Hung Clark T. , Ateshian Gerard A. 
Published: November 2021

Abstract
Significant strain-softening of articular cartilage along its depth direction has been observed in several studies [1,2], where the free-swelling equilibrium state of the tissue was taken to be the reference configuration for subsequent deformation. Microstructural models have been proposed to interpret this softening as buckling of pre-stressed collagen fibers [3,4]. In this study, we propose that a constitutive model which accounts for the disparity in tensile and compressive moduli of cartilage as well as the osmotic swelling response, can explain this experimentally observed strain-softening mechanism. The strain-softening behavior of the tissue is investigated experimentally and theoretically along three mutually perpendicular directions: directions parallel and perpendicular to the split line direction (1- and 2-direction), and normal to the articular surface (3-direction). A conewise nonlinear elasticity model is incorporated into the triphasic theory [5] to interpret this strain-softening in the context of Donnan osmotic swelling [6].
How Simplifying Assumptions Affect the Computation of Three-Dimensional Knee Loads in Cycling
Authors: Gregersen Colin S. , Hull M. L. 
Published: November 2021

Abstract
Determining the force and moment components transmitted by the knee is useful both to understand the etiology of over-use knee injuries common in cycling [1] and also to assess how well different interventions protect against over-use injury. Because the loads thought to be primarily responsible for over-use knee injury are the non-driving moments (varus/valgus and internal/external axial moments) transmitted by the knee [2], a 3-D model is necessary for calculating these loads. To our knowledge, no study has developed a model that includes complete 3-D kinematics of the segments to calculate these loads. Consequently one objective of this study was to develop a complete, 3-D model to calculate the intersegmental knee loads during cycling. A second objective was to use this model to examine how simplifying assumptions affect the 3-D knee loads.
Mechanical Factors Can Influence the Gender Differences in the Incidence of Non-Contact Injuries
Authors: Andriacchi Thomas , Camarillo David , Alexander Eugene , Dyrby Chris 
Published: November 2021

Abstract
The kinematics and kinetics of running to a stop and running and cutting were analyzed in the context of identifying mechanisms for non-contact injury to the anterior cruciate ligament of the knee. The study addressed the hypothesis that gender influences the mechanics of the way individuals perform running to a cut and running to a stop. The results demonstrate a difference during the early landing phase of the maneuver. Two patterns of limb loading were identified during the landing phase (foot strike to 200msec) of the run to cut maneuver. The results of this study suggest a potential injury mechanism associated with the biomechanics of landing in preparation for a run to stop or run to cut maneuver. Nine of ten male subjects in this population tended to land in a manner that produced a greater magnitude of the force component along the axis of the tibia. These findings provide new information that can be applied towards understanding gender difference patterns in non-contact ACL injuries.
Implant Technology: Knee Design for Improved Function and Wear
Authors: Bartel Donald , Edidin Av , Johnson Todd , Sculco Thomas , Wright Timothy 
Published: November 2021

Abstract
Total knee replacement has become an accepted treatment for diseased and damaged joints with over 150,000 surgeries performed annually in the United States alone. The popularity of knee replacement stems from the excellent clinical results, which in some reported series exceeded ninety percent at twenty years follow-up [1]. The high level of clinical success in elderly populations has spurred surgeons to extend the indications to younger patients; today, about a third of total knee replacements are implanted in individuals under sixty-five years of age.
A Method for the Rapid Prototyping of Custom Contoured Cushions
Authors: Parkinson Matthew B. , Huggins Jane E. 
Published: November 2021

Abstract
Decubitous ulcers (“pressure sores”) are a significant concern for people using wheelchairs. In fact, results published by the University of Kansas [1] indicate that over half of those using wheelchairs will develop a pressure sore at some point. This susceptibility is due to the conditions under which these ulcers develop: shear stress and pressure work together to cut off the blood supply to the surface tissue, which subsequently dies. Heat and moisture can increase the likelihood of this necrosis and the rate at which it occurs. Although sores can develop quickly (onset can occur in as few as fifteen minutes), they may take months to heal.
Appropriate seat cushion selection helps to mitigate the causative factors [2]. In particular, custom-contoured cushions (CCC) can offer dramatic improvements. Research has shown that CCC’s offer the best distribution of pressure and reduction of shear stress, reducing these factors by as much as 80% [3]. CCC’s are not commonly used, however, because the cost and time involved in design, manufacture, and delivery are prohibitive.
The obstacles of cost, time, and inconvenience, can be overcome by applying mass-customization and rapid-prototyping principles to the process used to create CCC’s. This involves automating the basic steps of the process: creating an electronic representation of the seating surface and machining that surface using a computer-controlled (CNC) mill. Similar systems have been put in place to automate a variety of processes, from the creation of custom orthotics for footwear to the design and creation of impeller wheels [4]. Such a system would be capable of producing a suitable custom-contoured cushion in minutes or hours rather than weeks or months.
Side Impact Pediatric Injury Studies
Authors: Sances Anthony , Harcourt John , Kumaresan Srirangam 
Published: November 2021

Abstract
Side impact injury and intrusion has been studied for many decades. According to the National Highway Traffic Safety Administration (NHTSA) side impacts account for 30% of all fatalities and 34% of all serious injuries to passenger car occupants [1,2]. A discussion of the Federal Motor Vehicle Safety Standard (FMVSS) 214 on the impactor, impacted vehicle and occupant motion is reported [3].
Applications of a Microfluidic Amplifier As a Bi-Stable Device in an Oxygen Delivery System
Authors: Macia Narciso F. 
Published: November 2021

Abstract
This paper presents the application of a planar, fluid amplifier which has been used as a bi-stable element in an intermittent, oxygen delivery device. The proportional fluid amplifier is made bi-stable by positive feedback: by connecting its outputs to its inputs, through a fluid resistor network. The fluidic fluid amplifier is the device that gave birth to the fluidics technology, in 1959, at the former Harry Diamond Laboratories (U.S. Army).
Mechanical Loading Modulates Gene Expression in Chondrocyte-Seeded Agarose Hydrogels
Authors: Lo Sansan S. , Mauck Robert L. , Seyhan Sara L. , Palmer Glyn D. , Mow Van C. , Hung Clark T. 
Published: November 2021

Abstract
A successful tissue engineered articular cartilage construct needs to possess mechanical, biochemical, and histological features similar to that of native cartilage in order to serve its load-bearing function. Agarose is a suitable scaffold material for chondrocyte cultures (1,2), allowing long-term maintenance of cell phenotype and the elaboration of a functional cartilage-like matrix. This culture system facilitates further elucidation of the roles of matrix and cell-matrix interactions in the regulation of chondrocyte response to mechanical loads. We have previously shown (3) that mechanical loading at a physiologic frequency can increase the rate of matrix deposition, increasing mechanical properties of the tissue engineered constructs (∼21 fold increases in HA over day 0 with loading vs. ∼4 fold increases for free swelling controls). We have also shown that dynamic loading of transiently transfected chondrocytes in agarose hydrogels for 1 hour at 10% strain increased aggrecan promoter activity by ∼1.5 fold (4). In this study we sought to further characterize the short term response of chondrocytes to static load (by measuring aggrecan promoter activity) and the effects of dynamic compression on aggrecan gene expression over a longer (3 day) culture period (by monitoring mRNA levels). Monitoring matrix gene expression during early times of culture, when there is little matrix accumulation and the cells deform directly with the matrix (5), may provide insights into cellular responses to strain and allow for the optimization of cartilage bioreactor conditions.
Genetic Manipulation of Adhesion Protein Expression to Regulate Tissue Remodeling
Authors: Phillips Jonathan A. , Roy Kanaklata , Imbalzano Anthony N. , Bonassar Lawrence J. 
Published: November 2021

Abstract
Physical forces play an essential role in life. Stimulating living cells or tissues with mechanical cues can conjure a myriad of biochemical and biophysical responses. [1,2,3] It is well known that mechanical cues, such as gravity, are important in proper tissue development and maintenance. [4] Likewise, mechanical cues have proven to be essential when engineering living tissue. [5] It has been shown that giving mechanical input to engineered load-bearing tissues will often result in a product more closely resembling the native tissue. [5,6] In contrast, studies done in the microgravity environment of outer space have shown that a loss of the constant mechanical input of gravity will result in loss of tissue mass. [7,8,9] Tissue engineering in microgravity systems has also resulted in “mechanically inferior” tissue. [10] It is now know that feedback from cellular mechanoreceptors is critical for proper development, maintenance, and remodeling of tissues. Actual mechanisms and biochemical pathways involved in mechanotransduction have not been fully elucidated and are subjects of intensifying research.
A Novel Approach to Modeling Mechanical Response of a Cell to External Loading
Authors: Venkatesan Vidhyashankar , Mukherjee Nilay 
Published: November 2021

Abstract
The cell is modeled as a fluid filled bag. The cytoskeletal elements radiate out from the center of the cell and attach to the cell membrane. The fluid pressure in the cell causes the membrane and the cytoskeletal elements to be in pretension. Using finite element methods, we show that by relatively small changes in the membrane dimensions, cytoskeletal properties and by reorganizing cytoskeletal structure, a cell can change its bulk modulus by two orders of magnitude. This approach combined with appropriate experiments can be used to model how cells respond and remodel in response to mechanical loads.
Nanomechanics Studies of Biomolecules Using Optical Tweezers
Authors: Stott Shannon , Williams Carrie , Bao Gang 
Published: November 2021

Abstract
Although many proteins in human cells have been identified, the structure-function relationships for most of them remain unknown. For example, protein motors such as kinesin and dynein were identified a long time ago but the exact mechanisms driving the motors are still elusive. Further, many protein molecules exhibit complex conformational dynamics which plays an important regulatory role in their functions. While it was common knowledge that DNA forms a double helix and that the helix is unwound by enzymes for transcription, the forces required to untwist the DNA was uncovered just recently. In carrying out nanomechanics studies of biomolecules such as DNA and proteins, we hope to answer some of the fundamental questions and more generally, to characterize the mechanical behavior of single molecules. The characteristics we wish to define include how a protein molecule deforms, unfolds, responds to a force and generates a force. Most proteins are small (1–100 nm) and the amplitudes of their deformation are even smaller, preventing them from being visible to a light microscope. Atomic force microscopy (AFM) can be used to measure the force-extension curves of proteins but the use of AFM is limited by the relatively high thermal noise. Thus, we elected to build an optical tweezers, a measurement system that can accurately measure forces in the range of 0.5–50 pN.
Constrained Multi-Body Dynamic Analysis of Shaft and Bearing Systems
Authors: Hoffmann F. , Rahnejat H. 
Published: November 2021

Abstract
A generic method of formulation for shaft and bearing systems in Lagrangian dynamics is described. The method incorporates combined lateral, axial and rotational rigid body dynamics of such systems, incorporating the restraining action of bearing supports through rolling element to races contact forces. For an example, the case of a horizontal dry vacuum pump is used. The vibration spectra obtained agree well with those encountered in practice.
On the Hamiltonian Formulation of Thin Free Liquid Sheets
Authors: Li Zhi 
Published: November 2021

Abstract
A Hamiltonian model is used to study the nonlinear distortion of thin free planar liquid sheets. A systematic asymptotic expansion procedure with the fluctuating value of the sheet velocity as the small parameter is developed for the propagation of long waves on liquid sheets. The first and second order systems of nonlinear evolution equations are derived.
Application of Neural Network Friction Component Model in Automotive Drivetrain Simulations
Authors: Cao M. , Wang K. W. , Fujii Y. , Tobler W. E. 
Published: November 2021

Abstract
In this research, an advanced hybrid neural network (AHNN) friction component model is integrated with an automotive drivetrain model for system simulations. The AHNN model accurately predicts the dynamic behaviors of transmission friction components over a broad operating range. It also allows variable sampling time steps in a numerical integration process. The AHNN model is trained using experimental data obtained from a powertrain dynamometer test stand. Since typical dynamometer measurements are acquired at locations away from friction components, a backtracking algorithm is developed to evaluate friction component torque during engagement. The trained AHNN model, together with a comprehensive drivetrain model, is implemented to simulate up-shifting process of an automatic transmission system under various operating conditions, including different oil temperature and engine throttle levels. Simulation results demonstrate that the AHNN friction component model can be effectively utilized as a part of drivetrain model to accurately predict transmission shift dynamics.
Dynamic Finite Element Modeling of Belt-Drives Including One-Way Clutches
Authors: Leamy Michael J. , Wasfy Tamer M. 
Published: November 2021

Abstract
In this study, a dynamic finite element model is developed for pulley belt-drive systems, including systems incorporating oneway clutches. The belt is modeled using truss elements, while the pulleys are modeled using rotating circular constraints, for which the driver pulley’s angular velocity is prescribed. Frictional contact between the pulleys and the belt is modeled using a penalty formulation with frictional contact governed by a Coulomb-like tri-linear friction law. One-way clutch elements are modeled using a proportional torque law supporting torque transmission in a single direction. The dynamic response of the drive is then studied by incorporating the model into an explicit finite element code, which can maintain time-accuracy for large rotations and for long simulation times. The finite element solution is validated through comparison to an exact analytical solution of a steadily-rotating, two-pulley drive. Several response quantities are compared, including the normal and tangential (friction) force distributions between the pulleys and the belt, the driven pulley angular velocity, and the belt span tensions. Excellent agreement is found. Results for a second belt-drive example involving a one-way clutch demonstrates the utility and flexibility of the finite element solution approach.
Simulation of Driver Behaviour in Heterogeneous Untidy Traffic in Developing Countries
Authors: Ahuja Sonal 
Published: November 2021

Abstract
This paper describes the research attempt to understand driver behaviour in heterogeneous, untidy traffic in developing countries through simulation. Cities of Dhaka, Bangkok and Delhi were identified as three case study areas where traffic surveys were conducted and driver behaviour analysed.
The paper tries to quantify the level of ‘aggressiveness’ in a particular driver-vehicle environment and proposes a simulation package to understand it. A modified Tetris approach has been developed to simulate heterogeneous and untidy traffic.
The study looks into the relationship of varying driver typologies, based on age and their relative aggression levels associated with trips and vehicle typologies in the three case locations. It proposes a simulation package to generate varying driver responses in context of slow moving and untidy traffic. The study reveals that age, and driver experiences are a significant factor in determining level of driver aggression. The driver response in a particular environment is a system optimum response of his individual state, in relation to the performance of system’s ‘driver-vehicle environment’. The study concludes that while heterogeneous and mixed traffic increases vehicle delays, and stops at the signalised links, untidy traffic reduces it. The combined effect of heterogeneity and untidiness cancel each other. The simulation reveals that segregation of traffic based on vehicular typologies and speeds leads to optimisation of link performance and environment. The research proposes a simulation model that can accurately simulate mixed, slow moving, and untidy traffic condition with varying degree of driver aggression and recommends its applications.
Car Crash Zones Based on Driver’s Collision Avoidance Behavior
Authors: Shiraishi Masatake , Tsuchiya Yukiya 
Published: November 2021

Abstract
There will be three kinds of collision avoidance operations when a driver encounters an object just ahead: braking and stopping before collision, steering the vehicle for avoidance, and steering and braking simultaneously. In any case, a certain crash-unavoidable zone exists to each vehicle. A “cross point” determined by the vehicle behavior is a key factor in designing a crash-unavoidable zone and depends mainly on vehicle speed, friction between the wheels and the road, and the steering angle. In this paper, this zone is determined by taking these factors into account.
Control of the Vehicle’s Running Properties As a Pre-Condition for Designing Wheel Drive Systems
Authors: Vantsevich V. V. , Amani L. 
Published: November 2021

Abstract
The paper presents a new approach of designing optimal wheel drive systems which improve considerably vehicle properties; including traction and velocity properties, fuel consumption, turnability, and ride stability. This approach creates the basis for synthesizing optimal circumferential wheel forces needed for designing optimum wheel drive systems for a particular vehicle.
At the beginning the optimum circumferential wheel forces should first be computed. These forces correspond to the optimum values of vehicle properties’ criteria simultaneously taken in aggregate with the required vehicle kinematics.
A single criterion optimization with limitation of the rest of criteria and limitation of optimized parameters is being presented. The objective function is being built for vehicles transporting a useful load.
All these theoretical developments are followed by the results of the mathematical modeling and computer simulation of an 8WD vehicle. The modeling and simulation are based on a previously developed algorithm for the optimization of the circumferential forces among the drive wheels (see [8]).