bluuebunny/crossref_metadata_2025 huggingface dataset:
Fecal microbiota relationships with childhood obesity: A scoping comprehensive review
Authors: de Cuevillas Begoña , Milagro Fermín I. , Tur Josep A. , Gil‐Campos Mercedes , de Miguel‐Etayo Pilar , Martínez J. Alfredo , Navas‐Carretero Santiago
Published: December 2021

Childhood obesity is a costly burden in most regions with relevant and adverse long‐term health consequences in adult life. Several studies have associated excessive body weight with a specific profile of gut microbiota. Different factors related to fecal microorganism abundance seem to contribute to childhood obesity, such as gestational weight gain, perinatal diet, antibiotic administration to the mother and/or child, birth delivery, and feeding patterns, among others. This review reports and discusses diverse factors that affect the infant intestinal microbiota with putative or possible implications on the increase of the obesity childhood rates as well as microbiota shifts associated with excessive body weight in children.
Relationship between Classification of Fabellae and the Severity of Knee Osteoarthritis: A Relevant Study in the Chinese Population
Authors: Zhang Lei , Wen You‐liang , He Chun‐ying , Zeng Yan , Wang Jun‐qiu , Wang Guo‐you
Published: December 2021

Objective

To classify the fabellae and discuss the relationship between the classification of fabellae and the severity of knee osteoarthritis (KOA) in Chinese.

Methods

From February 2019 to February 2020, 136 patients were measured and classified using three‐dimensional computed tomography (CT) reconstruction. According to the CT imaging characteristics, the fabellae were divided into five types: type I, a fabella on the lateral femoral condyle; type II, a fabella on the medial femoral condyle; type III, a fabella on the lateral femoral condyle and a fabella on the medial femoral condyle; type IV, two fabellae on the medial femoral condyle; and type V, two fabellae on the lateral femoral condyle. The severity of KOA was assessed on the Recht grade by magnetic resonance imaging (MRI). The data were analyzed with SPSS 24.0.

Results

The classification of fabellae were correlated with KOA grades (χ2 = 35.026, P < 0.05). In terms of KOA grades, grade I and grade II were occupied most by fabellar type II (32, 72.8%); type II and other types showed significant statistical difference (P < 0.05). Grade I and grade II were also mainly fabellar type IV (four, 100%). Fabellar type V's biggest component was grade III and grade IV (six, 75%). Type IV and type V showed significant statistical difference (P < 0.05).

Conclusion

The classification of fabellae were correlated with KOA grades. The type II may mean the lower KOA grades while type V may mean the higher KOA grades.
Viscoelastometric versus standard coagulation tests to guide periprocedural transfusion in adults with cirrhosis: A meta‐analysis of randomized controlled trials
Authors: Tangcheewinsirikul Nuanrat , Moonla Chatphatai , Uaprasert Noppacharn , Pittayanon Rapat , Rojnuckarin Ponlapat
Published: December 2021

Background and Objectives

Due to rebalanced haemostasis in cirrhosis, viscoelastometric testing (VET) is more accurate than standard coagulation tests (SCTs) in preprocedural haemostatic evaluation, resulting in decreased unnecessary transfusion. We aimed to determine the impact of VET‐guided strategy on postprocedural bleeding, periprocedural transfusion rates and quantities, transfusion‐related adverse events (TRAEs), lengths of stay (LOS) and mortality from randomized controlled trials (RCTs) of cirrhotic patients.

Methods

PubMed and EMBASE were searched for RCTs comparing VET‐guided with SCT‐guided transfusion in cirrhotic adults undergoing esophagogastroduodenoscopy, liver transplantation or other invasive interventions. Using random‐effects models, the pooled risk ratios (RRs) and/or mean differences (MDs) of postprocedural bleeding‐free events and the other outcomes were estimated alongside 95% confidence intervals (CIs).

Results

Of seven included RCTs (n = 421; 72.2% men; mean age 49.1 years), VET‐guided transfusion did not change postprocedural bleeding‐free statuses (RR 1.05; 95% CI 0.94–1.17). However, VET‐based algorithms decreased the rates of fresh frozen plasma (FFP; RR 0.52; 95% CI 0.35–0.77) and platelet transfusions (RR 0.34; 95% CI 0.16–0.73), the quantities of transfused FFP (MD −1.39 units; 95% CI −2.18 to −0.60), platelets (MD −1.06 units; 95% CI −2.01 to −0.12) and cryoprecipitate (MD −7.13 units; 95% CI −14.20 to −0.07) and the risk of TRAEs (RR 0.42; 95% CI 0.27–0.65). The overall mortality rates and LOS were not significantly different between two groups.

Conclusion

Compared with conventional SCT‐guided, VET‐guided strategy decreases periprocedural plasma and platelet transfusions and TRAEs, without increasing haemorrhagic complications, LOS or mortality in cirrhosis.
Challenges of Teaching ESP: A Review
Authors: Jande Lisa Vangohol , Ibrahim Noor Mala
Published: December 2021

English for Specific Purposes (ESP) has Noor Mala Ibrahim gained prominence and abundant research has been conducted on issues associated with it. However, research addressing the challenges of ESP teaching and learning continues to receive extensive attention focusing on issues ranging from the most appropriate methodology to use in ESP classrooms and contents to cover for   effective learning outcomes for the learners. The aim of this review paper is to give a brief overview of what ESP is all about, it also covers some issues faced by ESP practitioners while in the process of teaching. During the course of this review, the key words “ESP Challenges”, “ESP teaching methodology”, “ESP teacher” were used on Google scholar to search for relevant materials to the topic covering the range of years from 2012 - 2021. Twenty relevant materials were finally selected which are used for this review. This review finally concludes by offering solutions as to how these challenges can be overcome by practitioners to make ESP teaching more effective.
Language and Disciplinary Concepts in Corpus Linguistics: Investigating Corpus Data
Authors: Mohd Don Zuraidah , Knowles Gerry
Published: December 2021

This paper is intended for researchers involved in or contemplating research in corpus linguistics, and is concerned in particular with the language of corpus linguistics. It introduces and explains technical terms in the context in which they are normally used. Technical terms lead on to the concepts to which they refer, and the concepts are related to the procedures, including tagging and parsing, by which they are implemented. English and Malay are used as the languages of illustration, and for the benefit of readers who do not know Malay, Malay examples are translated into English. The paper has a historical dimension, and the language of corpus linguistics is traced to traditional usage in the language classroom, and in particular to the study of Latin in Europe. The inheritance from the past is evident in the design of MaLex, which is a working device that does empirical Malay corpus linguistics, and is presented here as a contribution to the digital humanities.
Dynamics of a Rumor Propagation Model With Stochastic Perturbation on Homogeneous Social Networks
Authors: Zhang Yuhuai , Zhu Jianjun
Published: December 2021

The rapid development of information society highlights the important role of rumors in social communication, and their propagation has a significant impact on human production and life. The investigation of the influence of uncertainty on rumor propagation is an important issue in the current communication study. Due to incomprehension about others and the stochastic properties of the users' behavior, the transmission rate between individuals on social network platforms is usually not a constant value. In this paper, we propose a new rumor propagation model on homogeneous social networks from the deterministic structure to the stochastic structure. First, a unique global positive solution of the rumor propagation model is obtained. Then, we verify that the extinction and persistence of the stochastic rumor propagation model are restricted by some conditions. If R̂0*<1 and the noise intensity σi(i=1,2,3) satisfies some certain conditions, rumors will extinct with a probability one. If R0*>1, rumor-spreading individuals will persist in the system, which means the rumor will prevail for a long time. Finally, through some numerical simulations, the validity and rationality of the theoretical analysis are effectively verified. The numerical results show that (1) on the premise that other parameters are determined, the increase of noise intensity can effectively control the spread of rumors; (2) cut off the way of spreading rumors and reduce the contact between ignorant and rumor-spreading individuals (i.e., reduce the value of α); popularize scientific knowledge, reducing the attraction of rumors (i.e., increase the value of β) or replacing rumors of emergencies with other hot topics (i.e., increase the value of η) can effectively curb rumor propagation.
A Noniterative Problem-Dependent Formula for Stiff Dynamic Problems
Authors: Chang Shuenn-Yih
Published: December 2021

A novel one-step formula is proposed for solving initial value problems based on a concept of eigenmode. It is characterized by problem dependency since it has problem-dependent coefficients, which are functions of the product of the step size and the initial physical properties to define the problem under analysis. It can simultaneously combine A-stability, explicit formulation, and second-order accuracy. A-stability implies no limitation on step size based on stability consideration. An explicit formulation implies no nonlinear iterations for each step. The second-order accuracy with an appropriate step size can have good accuracy in numerical solutions. Thus, it seems promising for solving stiff dynamic problems. Numerical tests affirm that it can have the same performance as that of the trapezoidal rule for solving linear and nonlinear dynamic problems. It is evident that the most important advantage is of high computational efficiency in contrast to the trapezoidal rule due to no nonlinear iterations of each step.
J Predictions for Defective Pipe Elbows Via the Reference Stress Method
Authors: Lei Yuebao , Budden Peter
Published: December 2021

In R6, the J-based failure assessment diagram (FAD) method is used in the fracture assessment and is underpinned by the reference stress J scheme. Therefore, an assessment using the R6 FAD method is equivalent to a J prediction using the reference stress method. In this paper, the effect of global and local limit load solutions for defective elbows on the reference stress and hence the J predictions is investigated using published three-dimensional elastic-plastic finite element (FE) J results, in order to create guidance for users to follow when performing structural integrity assessments of defective elbows using the R6 procedure. The results show that using the global limit load solutions recommended in this paper can lead to good and reasonably conservative J predictions. However, the availability of global limit load solutions is very limited. The results also show that using the local limit load evaluated from the local limit load model recommended in this paper can lead to conservative J predictions for most of the cases considered.
Performance Comparison of Nonlinear and Intelligent Control Strategies on the Ball and Beam Dynamic System
Authors: Wagner John R. , Momot Michael E.
Published: December 2021

A variety of nonlinear and intelligent control strategies have been proposed to control nonlinear processes. To assist the controls practitioner in evaluating the potential performance of different control methodologies, four nonlinear and intelligent control strategies are examined and compared on the classic ball and beam dynamic system. The nonlinear control designs include three approximate input-output linearizations, a kth-order approximation of the plant zero-error manifold, and a variable structure system controller. A fuzzy logic controller, with an expandable set of control rules, is designed as an alternative to these model-based schemes. Simulation results are presented to demonstrate the ability of each controller in tracking a prescribed trajectory. The performance of each control strategy is discussed in terms of convergence time, steady-state error, control authority, and ease of implementation.
A Comprehensive Squeeze Film Model of the Planar Circular Section Implemented in the Saber Simulator
Authors: Wang J. M. , Herbison D.
Published: December 2021

This paper presents a comprehensive squeeze film model of planar circular plates, implemented in the MAST™ modeling language for use with the Saber™ simulator. Hydrodynamic pressure between two plates is a function of the displacement, velocity and dimensional parameters of the circular plates. The pressure generated in film has a distributed nature and it depends on, beside other factors, the pressure boundary condition. The total force acting on the plate surfaces is the integration of the pressure distribution. The viscosity of lubricants is modeled as the function of both pressure and temperature. Cavitation region occurred inside the squeeze film is considered by the model internally. Cavitation occurring at the boundary is modeled by connecting the hydraulic pin to the ideal cavitation template of the Saber template library. Saber outputs are discussed for some important influential effects under different operating conditions. The paper also includes discussion of the ideal cavitation and the hydraulic chamber templates which are embedded to support the squeeze film simulation.
Delamination Suppression in Sandwich Beams Using Translaminar Reinforcements
Authors: Wallace Brian T. , Sankar Bhavani V. , Ifju Peter G.
Published: December 2021

The present study is concerned with translaminar reinforcement in a sandwich beam for preventing buckling of a delaminated face-sheet under axial compression. Graphite/epoxy pins are used as reinforcement in the thickness direction of sandwich beams consisting of graphite/epoxy face-sheets and a Aramid honeycomb core. Compression tests are performed to understand the effects of the diameter of the reinforcing pins and reinforcement spacing on the ultimate compressive strength of the delaminated beams. A finite element analysis is performed to understand the effects of translaminar reinforcement on the critical buckling loads and post-buckling behavior of the sandwich beam under axial compression.
Precise Design and Analysis of Wet Layup Composite Repairs
Authors: Kress Greg
Published: December 2021

The increasing size and cost of composite structures combined with the increased loading requirements placed on such components has heightened the need for performing durable and thoroughly analyzed composite repairs. Precise applications of composite repairs possess many difficulties from both a maintenance and engineering standpoint. The composite repair engineer is often limited by the repair materials and processing equipment that are available, the data to define the loads placed on the structure, and physical limitations such as the inability to remove a panel from the aircraft, heat sinks, and underlying structure. This presentation describes the repair configuration, materials and analysis techniques for performing the precise design and analysis of wet layup composite repairs.”
Functional Specifications for Tele-Immersive Product Evaluation
Authors: Thompson D. , Banerjee A. , Banerjee P. , DeFanti T. , Retterer S.
Published: December 2021

A novel virtual tele-immersive product evaluation environment is conceived. The components include a robust Virtual Reality (VR) hardware system, associated VR driving software, development tool for the tele-immersive virtual environment, networking software, user representation scheme and tools for developing 3D models and incorporating dynamic properties into the models. We have developed a model to allow users to collaboratively evaluate products using the CAVE™, Performer, CAVERN, CAVEActors, Pro/ENGINEER, and ADAMS software libraries.
Design of an Interactive Virtual Factory Using Cell Formation Methodologies
Authors: Kesavadas T. , Ernzer M.
Published: December 2021

This paper describes an interactive virtual environment for modeling and designing factories and shop floors. The factory building tool is developed as an open architecture in which various modules can be utilized to quickly implement factory design algorithms ranging from plant layout to factory flow analysis. Software modules and utilities have been implemented to allow easy set-up of the visual interface. In this paper this virtual factory is used to implement cellular manufacturing (CM) system. CM has traditionally been a very complicated system to implement in practice. However the productivity rise obtained by the successful implementation of the system has been proved to be immense. Several issues involved in implementing CM within our virtual factory machine modeling and interface designs for defining the cells, are discussed. The mathematical clustering algorithm called Modified Boolean Method was implemented to automatically generate complex virtual environments. The virtual factory makes the process of CM-based factory design a very easy and intuitive process. Virtual factory interface also allows easy reassignment of machines and parts, subcontracting of bottleneck parts and rearranging of machines within the same design environment, making this a productive industrial tool.
Comparison of Free Flexural Vibrations of Composite Plates or Panels Stiffened by a Central and a Non-Central Plate Strip
Authors: Yuceoglu U. , Özerciyes V.
Published: December 2021

The natural frequencies and the corresponding mode shapes of two classes of composite base plate or panel stiffened by a central or a non-central plate strip are analyzed and compared with each other. In each case, the base plates and the single, stiffening plate strips are assumed to be dissimilar orthotropic plates connected by a very thin, yet deformable adhesive layer. The free bending vibration problems for the two cases are formulated in terms of the Mindlin Plate Theory for orthotropic plates. The governing equations are reduced to a system of first order equations. The solution technique is the “Modified Version of the Transfer Matrix Method”. The effects of the bonded central and non-central stiffening strip on the mode shapes and the natural frequencies of the composite plate or panel system are investigated. Some important conclusions are drawn from the numerical and parametric studies presented.
Leaky Wave Contributions to Ultrasonic Scattering Amplitudes for Truncated Objects
Authors: Marston Philip L. , Morse Scot F. , Gipson Karen
Published: December 2021

In ultrasonic nondestructive evaluation and sonar imaging, scattering contributions by leaky waves on truncated objects can be important for enhancing the visibility of certain of the borders of the scatterer. A method of approximating the leaky wave contributions is reviewed together with recent experimental and computational tests for evaluating that method in situations where the scattering contributions are large. The tests include meridional ray contributions to the scattering by tilted solid cylinders and cylindrical shells and Rayleigh wave contributions for steel cubes in water.
Use of Geometric Symmetry in Transducer Array Interaction Problems
Authors: Benthien George W.
Published: December 2021

To predict the performance of transducers operating in an array it is necessary to consider the acoustic interaction between transducers. This analysis usually involves solving a system of equations involving certain transducer impedances as well as mutual radiation impedances between transducer elements. This problem can be simplified by taking into account any geometric symmetries that might be involved. Unlike finite element problems where geometric symmetry can be enforced through boundary conditions, it is necessary in these problems to consider the structure of the radiation impedance matrix induced by the geometric symmetries. In this paper I will show how computation time can be reduced considerably by taking advantage of the special symmetry structure of these matrices.
An Analytical Solution to the Electrostatic Actuation of an Asymmetric Combdrive
Authors: Yeh J.-L. Andrew , Tien Norman C. , Hui Chung-Yuen
Published: December 2021

A model for the electrostatic forces generated by an asymmetric combdrive has been developed. Using complex variable techniques, an analytical solution to out-of-plane electrostatic actuation is obtained in closed form. The peak force depends on the thickness of the movable fingers and the amount of overlap between the combs. In addition, the in-plane actuation of an in-plane interdigitated combdrive can also be interpreted using our solution. For an in-plane combdrive, the critical engagement length of the combs, which is required for generating a constant force with variation within 1%, is a factor of 1.24 times the separation gap.
Controlling and Coordinating Mobile Micro-Robots: Lessons From Nature
Authors: Melhuish Chris
Published: December 2021

Assuming that mobile micro-scaled robots will be built in the future it is reasonable to speculate how such machines can be controlled. At the micro-scale robots will experience considerable limitations. Against this background, and inspired by natural collective systems, the paper explores collective minimalist mechanisms for the key aspects of moving through the environment, regulating the size of robot groups and acting on the environment.
Modeling, Design and Fabrication of a Microdevice for E-Field Cell Lysis
Authors: Smekal Thomas , Briscoe Cindy , Chan Tony , Chang Yung , Dobrin Seth , Gallagher Sean , Groninger Heidi , Marrero Rob , Rhine David , Yu Huinan , Grodzinski Piotr
Published: December 2021

The development of an electric field cell lysis device for microfluidic applications will be presented. Detailed modeling of the electrode configuration for the optimization of the electric field has been performed. Device design and fabrication has been accomplished using traditional integrated circuit (IC) manufacturing techniques. As a result, murine lymphocytes have been lysed using several electrode configurations. The requisite electric field strength and pulse parameters for cell lysis were determined. The non-specific adsorption of the released DNA to the materials used in the fabrication of the device was observed. Surface passivation of the fabrication materials was effected through the use of silanization compounds.
The Effect of Residual Stresses on the Deformation of Semi-Circular Micromachined Beams
Authors: Tsou Chingfu , Fang Weileun
Published: December 2021

In this research, a semi-circular micromachined beam is proposed to reduce the out-of-plane deformation caused by the residual stresses. The side view of the semi-circular beam is similar to that of the cantilever. However, the end conditions of the semi-circular beam are similar to that of the microbridge. Although the micromachined cantilever would not be deformed by the mean compression, it is bent significantly by the residual gradient stress. On the other hand, the microbridge would not be bent by the gradient residual stress, however, it would be buckled by the mean compression. As demonstrated through the analytical and experimental results, the out-of-plane deformation due to bending and buckling is significantly reduced for the semi-circular micromachined beam. Thus, the flatness of the micromachined suspensions is improved. The more traditional techniques in which the out-of-plane deformation is reduced by lowering the net residual stresses of thin films can be supplemented by the use of semi-circular micromachined beam.
Transport of Particle-Laden Fluids Through Fixed-Valve Micropumps
Authors: Jang Ling-Sheng , Morris Christopher J. , Sharma Nigel R. , Bardell Ron L. , Forster Fred K.
Published: December 2021

Micropumps designed for the flow-rate range of 100–1000μl/min have been developed by a number of research groups. However, little data is available regarding the ability of various designs to directly transport liquids containing particles such as cells, microspheres utilized for bead chemistry, or contaminants. In this study the ability of pumps with no-moving-parts valves (NMPV) to transport particles was investigated. The results showed that a NMPV micropump was able to directly pump suspensions of polystyrene microspheres from 3.1 to 20.3μm in diameter. The pump functioned without clogging at microsphere number densities as high as 9000 particles/μl of suspension, which corresponded to over 90,000 particles per second passing through the pump at a flow rate of 600μl/min. Performance with polystyrene microspheres was the same as pure water up to the point of cavitation. Microspheres manufactured with negative surface charge cavitated less readily that other microspheres studied that were manufactured without surface charge. However, cavitation did not appear to be a function of microsphere size, total surface area or number density. Thus pumping polystyrene microspheres was found to be more affected by surface effects than by size, surface area or number density within the range of parameters considered. In the case of charged microspheres, the maximum flow rate was reduced by 30% compared to pure water whereas for uncharged microspheres the maximum flow rate was reduced by approximately 80%.
Theoretical and Experimental Study of Mesoscopic Impactors
Authors: Yi Mingqiang , Hu Howard , Bau Haim H. , Erickson K.
Published: December 2021

An inertial impactor is a device that separates particles from a gas stream according to their mass. The characteristics of two different types of mesoscopic impactors, one with and one without a collection cup, were studied theoretically and experimentally. The theoretical study consists of a numerical solution of the Navier-Stokes equations for the fluid’s flow field and a solution of Newton’s equation of motion for the particles. The particle cut-off sizes and the impactor’s efficiency curves were computed as functions of the jet-to-plate distance, nozzle size, cup size, and the jet’s Reynolds number (Re < 100). Prototypes of impactors were fabricated in low temperature co-fired ceramic tapes. Preliminary experiments were carried out to determine the collection efficiency as a function of particle size and the Reynolds number. The experimental results were critically compared with theoretical predictions.
Development of a Tire/Pavement Contact-Stress Model Based on an Artificial Neural Network
Authors: El-Gindy Moustafa , Lewis Heidi L. , Lewis A. Scott
Published: December 2021

This paper presents comprehensive tire/pavement contact-stress models based on the Artificial Neural Networks developed by the authors at the Pennsylvania Transportation Institute and Applied Research Laboratory of the Pennsylvania State University. These models represent the first mathematical representation of measured, vertical contact stress at wide ranges of vertical loads and inflation pressures for two types of tires. The Developed ANN model has the capabilities to generate complex stress distribution patterns under a tire at any given load and inflation pressure for a specific tire type used for the ANN training. The information given here is considered to be an important contribution to the ongoing efforts to improve tire/pavement contact stress modeling and analysis. The neural network representation of a tire contact stress distribution is denoted as “Neuro-Patch Model”.

The neural network models have been trained using precisely measured, three-dimensional contact-stress distribution patterns obtained from low speed rolling tire tests conducted by the University of California at Berkeley. This data has been supplied by the Federal Highway Administration (FHWA). In this study two types of tires, namely a 11R22.5 Radial-Ply and a 10.00 × 20 Bias-Ply truck tire, were modeled at different inflation pressures ranging from 520 kPa to 920 kPa and vertical loads ranging from 26 kN to 56 kN.
Development of the General-Purposed Program Based on the Concept of Subsystem Assembly for the Analysis of Dynamic Characteristics of Power Transmission System
Authors: Lim Weon-Sik , Jo Han-Sang , Jang Wook-Jin , Lee Jang-Moo , Park Yeong-Il
Published: December 2021

This paper presents the main algorithms of POTAS-MSM (POvver Transmission Analysis Software for Multi-Slipping Mechanism), which are based on the concept of subsystem assembly and the self-determination technique for the system degrees-of-freedom. This software allows users to quickly and easily model the various and complex configurations of power transmission systems and their components. With these dynamic models, the program can be used to evaluate system performances, transient phenomena such as shift, and other dynamic problems. The program has feature to effectively handle nonlinear model, to quickly examine the various changes of system behavior caused by design modification, and to provide stable solution to arbitrary operating condition or control logic. The ability of the developed program is demonstrated through the simulations and the experiments of a transmission model.
Feasibility Analysis of Open-Loop Rollover Control of Heavy Freight Vehicles
Authors: Liu P. J. , Rakheja S. , Ahmed A. K. W.
Published: December 2021

In this paper, a comprehensive three-dimensional heavy vehicle model is developed to investigate the effectiveness of an open-loop roll instability control. The steering system compliance, roll steer, bump steer, ackerman steer and wrap steer are incorporated in the vehicle model, along with comprehensive tire model and ABS algorithm. Time delays due to driver’s reaction and the transportation lag of the braking system are characterized by a variable called reaction delay. The rollover indicators in terms of roll safety factor, tractor and trailer lateral accelerations and roll angles, and the rearmost axle roll angle are investigated for their effectiveness for open-loop roll stability control in various cornering and evasive maneuvers, road conditions, braking efforts, and different reaction delays.
Longitudinal Front Wheel Drive Vehicle Maneuvers Considering DC-Motors Constraints
Authors: Bestaoui Yasmina
Published: December 2021

This paper is concerned with trajectory generation of vehicles taking into account the vehicle’s dynamics and the actuators’ constraints in voltages and currents. Motion generation is formulated as an optimisation problem with a mixed energy-time objective function. Usual kinematics constraints are not sufficiently representative of the reality, thus we focus on more realistic constraints: on the acceleration, the jerk, the maximum power which can be transferred to the road and voltage and current DC actuator constraints.
Two-Bundle Posterior Cruciate Ligament Reconstruction: An In Vitro Analysis of Graft Placement and Tension
Authors: Shearn Jason T. , Mannor Dana A. , Grood Edward S. , Levy Martin S. , Noyes Frank R.
Published: December 2021

The posterior cruciate ligament (PCL) provides over 90% of the forces that resist posterior tibial translation (Butler et al., 1980). When the PCL is ruptured the resulting change in joint kinematics and kinetics can lead to patello femoral pain and joint arthritic. These changes can effect daily activity requiring reconstruction (Satku et al, 1984). Although the goal of PCL reconstruction is to restore the normal limit of posterior tibial translation (Andrews et al., 1994), there is a frequent recurrence of posterior translation (Markolf et al Part I, 1997). The recurrence is believed to be caused by graft elongation/failure. The failure is probably due to non-uniform load sharing among graft fibers combined with large forces and the loss of strength during remodeling (Markolf et al Part II, 1997). The governing hypothesis of this study is that improving load sharing among graft fibers can reduce graft failures. We are pursuing a technique that divides the graft into two bundles so that the bundles have separate attachments and can be separately tensioned. The purpose of this study was to determine the ability of one and two bundle reconstructions to control posterior translation, and to determine how femoral attachment location affected bundle tension.
Linear Stability Analysis of a Collapsible-Tube Model
Authors: Mawasha P. Ruby , Gross Richard J. , Conway Ted
Published: December 2021

A linear stability analysis is performed for a collapsible tube model consisting of a reservoir with inlet and outlet flow conditions. The downstream pressure in the collapsible regime is modeled as a cubic nonlinearity. From the nonlinear model, we assume small perturbations around the steady states and utilize Liapunov stability criteria to describe the linear model. Steady-state pressure drops, stable and unstable boundaries are determined analytically for ranges of mass flow rate and compressible volume in the reservoir. Mechanisms that give rise to unstable behavior of pressure and flow rates in collapsible tube systems are examined based on numerical results. The model also provide us with stable and unstable boundaries that may give us the insight on the operation, control, and safety of collapsible tube systems in biological systems such as veins, arteries etc.
Progress Towards Prospective Computational Imaging Studies of Hemodynamics and Vascular Disease in Humans
Authors: Steinman David A. , Ladak Hanif M. , Thomas Jonathan B. , Milner Jaques S. , Lee Donald H. , Rutt Brian K. , Spence J. David
Published: December 2021

Magnetic resonance imaging (MRI) allows us to resolve vascular anatomy with submillimeter resolution non-invasively, making it possible to monitor the development of atherosclerosis in vivo (Skinner et al, 1995). Although imaging technology is not yet mature enough to simultaneously resolve the complex flow patterns, computational fluid dynamics (CFD) can reliably and efficiently model pulsatile flow in realistic, three-dimensional arterial geometries. By using imaged lumen geometry and flow rate as input parameters to such model studies, we can reconstruct the local in vivo hemodynamic environment.
Role of Nucleus on Leukocyte Recovery
Authors: Kan Heng-Chuan , Shyy Wei , Udaykumar H. S. , Vigneron Philippe , Tran-Son-Tay Roger
Published: December 2021

In the present study, we investigate the effect of nucleus size and position, and the relative rheological properties of cytoplasm and nucleus, on cell recovery dynamics. Two nucleus sizes corresponding to that of neutrophil and lymphocyte are considered. Direct comparison between numerical simulations and experimental observation is made. Results indicate that the time scale ratio between the nucleus and cytoplasm plays an important role in cell recovery characteristics. Comparable time scales between the two cell components yield favorable agreement in recovery rates between numerical and experimental observations; disparate time scales, on the other hand, result recovery behavior and cell shapes inconsistent with experiments. Furthermore, it is found that the nucleus eccentricity exhibits minimum influence on all major aspects of the cell recovery characteristics. The present work offers additional evidence in support of the compound cell model for predicting the rheological behavior of leukocytes.
A Mathematical Model for Bone Remodeling
Authors: Hazelwood Scott J. , Martin R. Bruce , Rodrigo Juan J. , Rashid Mark M.
Published: December 2021

A bone remodeling algorithm based on disuse and damage repair was developed in this study. Important elements of the bone remodeling process, including the delay between resorption and formation of bone and the resulting porosity, were included in the algorithm. A study of the dynamic response of the algorithm indicated oscillatory behavior for disuse situations and critically sensitive behavior in overload situations beyond a threshold load. Application of the algorithm to a finite element model of the femur reproduced the observed internal structure. The model is being used in further studies to investigate remodeling around implant stems and bone diseases and their treatment.
Load-Displacement Characteristics of an Implanted Nuclear Pouch in the Lumbar Spine
Authors: Dooris Andrew P. , Grosland Nicole M. , Goel Vijay K. , Drake John S. , Ahern James W. , Roche Karen M. , Wolfe Steven J.
Published: December 2021

Fusion of the spinal segments is typically done to prevent or correct deformity, stabilize the spine after trauma or pathologic destruction, or eliminate painful movement of the spinal segments. Spinal interbody arthrodesis typically requires considerable patient exposure, necessary for discectomy and graft implantation, and resultant morbidity. Some researchers suggest nuclear replacements as active joint mobilizers, while others suggest full disc replacements, and although some biomechanical consideration has been given, results are unclear. We consider here a device which proposes to reduce surgical morbidity while promoting stability by fusion. The device investigated here is a bone-chip pouch, which fills the nuclear space. We present here initial findings of this device in lumbar cadaveric specimens.
Knee Joint Response to Compressive Loading and Ligament Injury
Authors: Lee Jordan , Fronczak Frank
Published: December 2021

The knee joint is a six degree-of-freedom joint which has a complex response to loading. The joint has a characteristic behavior for particular ligament injuries such as anterior cruciate ligament failure. The response of the joint to a combination of compressive loading and secondary loadings was examined in this study. The secondary loadings were: an anterior force, a valgus moment, an internal torque, or an external torque.

A goat model was used with 17 specimens testing different ligament injuries in vitro, specifically stretched or severed anterior cruciate ligaments (ACL) and lateral collateral ligaments (LCL). The femur was held fixed and the tibia loaded in a specially designed apparatus, allowing complete six degree-of-freedom joint motion. The motion of the tibia with respect to the femur was recorded using a coordinate measuring machine. The knee joint demonstrated sensitivity to ACL injuries but not to LCL injuries for the loadings examined. The response to ACL injuries was more highly dependant on the compressive load than the secondary loadings for all tests.
A Fibril Reinforced Poroelastic Model of Articular Cartilage Including Depth Dependent Material Properties
Authors: Li L. P. , Buschmann M. D. , Shirazi-Adl A.
Published: December 2021

Articular cartilage is a highly nonhomogeneous, anisotropic and multiphase biomaterial consisting of mainly collagen fibrils, proteoglycans and water. Noncalcified cartilage is morphologically divided into three zones along the depth, i.e. superficial, transitional and radial zones. The thickness, density and alignment of collagen fibrils vary from the superficial zone, where fibrils are oriented parallel to the articular surface, to the radial zone where fibrils are perpendicular to the boundary between bone, and cartilage. The concentration of proteoglycans increases with the depth from the cartilage surface. These regional differences have significant implications to the mechanical function of joints, which is to be explored theoretically in the present work by considering inhomogeneity along the cartilage depth. A nonlinear fibril reinforced poroelastic model is employed as per Li et al. (1999) in which the collagen fibrils were modeled as a distinct constituent whose tensile stiffness was taken to be very high and be strain dependent but whose compressive stiffness was neglected.
Airbag Inflators
Authors: Broadhead William G. , Zinke D. Theodore
Published: December 2021

The design of an airbag restraint system presents a classic engineering challenge. There are numerous design parameters that need to be optimized to cover the wide range of occupant sizes, occupant positions and vehicle collision modes. Some of the major parameters that affect airbag performance include, the airbag inflator characteristics, airbag size and shape, airbag vent size, steering column collapse characteristics, airbag cover characteristics, airbag fold pattern, knee bolsters, seat, seat belt characteristics, and vehicle crush characteristics. Optimization of these parameters can involve extremely costly programs of sled tests and full scale vehicle crash tests. Federal Motor Vehicle Safety Standards (FMVSS) with regard to airbag design are not specific and allow flexibility in component characteristics.

One design strategy, which is simplistic and inexpensive, is to utilize a very fast, high output gas generator (inflator). This ensures that the bag will begin restraining the occupant soon after deployment and can make up for deficiencies in other components such as inadequate steering column collapse or an unusually stiff vehicle crush characteristic. The use of such inflators generally works well for properly positioned occupants in moderate to high-speed frontal collisions by taking advantage of the principle of ridedown. When an airbag quickly fills the gap between the occupant and the instrument panel or steering wheel it links him to the vehicle such that he utilizes the vehicle’s front-end crush to help dissipate his energy, thus reducing the restraint forces. Unfortunately, powerful airbag systems can be injurious to anyone in the path of the deploying airbag. This hazard is present for short statured individuals, out of position children or any occupant in a collision that results in extra ordinary crash sensing time. Currently, the National Highway Traffic Safety Administration (NHTSA) is proposing to rewrite FMVSS 208 to help reduce such hazards.
An Analytical Investigation of Whiplash Injury Risk Related to Head Restraint Position
Authors: Kleinberger Michael , Sun Emily , Saunders James , Zhou Zaifei
Published: December 2021

Although no consensus currently exists on the mechanisms and tolerances of whiplash injuries, it is generally accepted that head restraint position plays an important role in determining injury risk. This study explores the effects of head restraint position on whiplash injury risk by analyzing a series of rear impact simulations. Head restraint height and backset are varied over a wide range of values and a number of engineering parameters believed to be related to whiplash injury risk are examined. Results indicate that relative motion between the head and torso is strongly related to head restraint position and relative stiffness of the head restraint and seat back. Whiplash injury risk is believed to be related to this relative motion.
Efficient Computation of Strain Energy Release Rate in Crack Growth Simulation
Authors: Chen D. J.
Published: December 2021

This paper utilizes an automated process to simplify the calculation of the strain energy release rate (SERR) during the crack propagation. The convergence of a finite element solution is achieved by adaptive re-meshing scheme with an error estimator of the linear strain triangular (LST) elements. As the desired mesh density is achieved, computation of the SERR using virtual crack closure technique (VCCT) can be obtained by using the static condensation scheme without re-analyzing the finite element models. Thus, the amount of computational and modeling time can be significantly reduced in the analysis of the crack propagation.
Influence of Fiber Orientation on Interlaminar Fracture Toughness of Composites
Authors: Yang Z. , Sun C. T.
Published: December 2021

In this paper, an experimental investigation and a finite element analysis on interlaminar fracture behavior and fracture toughness of multidirectional composite laminates are presented using end-notch flexure specimens. The (0 / θ) interfaces are considered. The fracture toughness of the interfaces is obtained from the experimental records of load and displacement histories, which is then calibrated by a finite element analysis based on the pseudo three-dimensional assumption. The fracture modes are separated and represented by fracture mode phase angles. Finally, the interlaminar fracture toughness and fracture mode mixities as functions of fiber orientation θ are established.
Machining Performance of PM Material Containing MnX Additives
Authors: Barnes S. , Nash M. J. , Lim M. H.
Published: December 2021

Improvements in the machining performance of ferrous powder metallurgy (PM) materials has recently been reported by one of the main manufacturers of metal powders. This improvement in machinability reportedly being achieved by the addition of a new free-machining additive which is marketed under the trade name of “MnX”. The work reported here, investigated this claim by comparing the performance of three PM materials with the same basic composition but different free-machining additives. The first material contained no free-machining additive, the second, contained the conventional manganese sulphide (MnS) additive and the third contained the new MnX additive. A turning operation was used to compare the performance of the three materials at cutting speeds in the range of 100–250 m/min using titanium nitride (TiN) coated UE6005 carbide inserts. The relative performance of the three materials was compared by measuring cutting forces, tool wear and the surface finish produced on the workpiece. It was found that at all cutting speeds investigated, the material containing MnX gave a superior performance. However, at higher cutting speeds the superiority of the material containing MnX was much more significant. In contrast, at the lowest cutting speed of 100 m/min, it was found that although the material containing MnX continued to exhibit the best performance, the differences between the three materials were substantially reduced and the material containing no free machining additive actually generated slightly less wear than the material containing MnS. The results therefore confirm that the new MnX additive is superior to the conventional MnS additive. However, this work has also demonstrated that relatively high cutting speeds are needed in order to obtain optimum benefits from the new additive.
Modeling and Compensation of Hysteresis in Piezoceramic Transducers for Vibration Control
Authors: Lee Soon-Hong , Royston Thomas J. , Friedman Gary
Published: December 2021

Hysteretic behavior in piezoceramic transducers is investigated theoretically and experimentally. The applicability of the rate-independent generalized Maxwell resistive capacitor (MRC) hysteresis model is established. Methods for MRC and inverse MRC online model identification are developed by first establishing that the MRC and its inverse are the same particular cases of the classical Preisach hysteresis model. This enables use of the extensive mathematical framework that has been developed for Preisach models. A method of incorporating the MRC model in a feedforward control scheme for hysteresis compensation is also presented. Experimental studies on a 1-3 piezoceramic composite support the theoretical developments and their applicability to piezoceramics.
Modeling and Optimization Issues Concerning a Circular Piezoelectric Actuator Design
Authors: Coorpender Steven J. , Finkel Daniel , Kyzar Jennifer , Sims Robert , Smirnova Alexandra B. , Tawhid Mohamed , Bouton Chad E. , Smith Ralph C.
Published: December 2021

An electromechanical model for a circular piezoelectric actuator is developed. A critical challenge in certain applications employing piezoceramic actuators is to maximize the displacement provided by the actuator while minimizing it power consumption. This problem is addressed here by developing an electromechanical model which can be used to optimize the volume displacement to admittance ratio for various circular actuator designs. The model includes multiple layers with independent radii which can be varied to optimize performance. The piezoceramic, bonding, plating, and mounting materials can be varied to accommodate various design criteria. An advantage of the model lies in the property that for a variety of material configurations, analytic solutions can be obtained. Numerical examples demonstrating the properties of the model are presented.