bluuebunny/crossref_metadata_2025 huggingface dataset:
Durability Properties Characterization of Sn62Pb36Ag2 Solder Alloy
Authors: Haswell Peter , Dasgupta Abhijit
Published: November 2021

The cyclic durability properties of a near-eutectic Sn62Pb36Ag2 solder alloy are explored using a piezoelectric-actuated Thermo-Mechanical-Microstructural (TMM) test apparatus. The miniature test specimens are an Iosipescu-type shear configuration with a typical joint thickness of 180μm, so that significant length-scale effects are captured. Cyclic, total displacement-controlled tests are executed at room temperature and at various strain rates and amplitudes. A variety of failure models are employed to quantify the durability of this alloy, compared to the baseline Sn-Pb eutectic solder.

Power-law relationships between the number of cycles to failure and three damage metrics (total strain, inelastic strain and hysteresis energy) are established for the Sn62Pb36Ag2 solder alloy. There is good agreement between the results presented here and other data in the literature for the inelastic strain and hysteresis energy models. The parameters of the total strain-based damage model do not agree well with other published data. A discussion of these results is included, along with details of recent developments in the test method used here, as well as other future work.
Length Scale and Aging Effect on the Mechanical Properties of a 63Sn-37Pb Solder Alloy
Authors: Lim T. Jesse , Lu Wei-Yang
Published: November 2021

In this work, uniaxial tensile testing of a 63Sn-37Pb alloy with different specimen sizes and aging conditions had been carried out. Although the stress-strain responses of different specimen sizes and aging conditions differs, the ultimate strength of the specimens with 16 hours, 100°C aging are similar for the sizes tested. The specimens with 25 days, 100°C aging have different stress-strain response with different sizes, and have a lower ultimate strength and higher failure strain compared to 16 hours, 100°C aging specimens.
Design and Evaluation of Artifact-Resistant Finger-Ring Plethysmographic Sensors
Authors: Rhee Sokwoo , Yang Boo-Ho , Asada Haruhiko H.
Published: November 2021

A miniaturized, telemetric, photoplethysmograph sensor for long-term, continuous monitoring is presented in this paper. The sensor, called a “ring sensor”, is attached to a finger base for monitoring beat-to-beat pulsation, and the data is sent to a host computer via a RF transmitter. An efficient double ring design is developed to lower the influence of external force, acceleration, and ambient light, and to hold the sensor gently and securely on the skin, so that the circulation at the finger may not be obstructed. A prototype ring sensor is designed and built based on the artifact-resistive attachment method. It is verified through experiments that the ring sensor is resistant to interfering forces and acceleration acting on the ring body. Benchmarking tests with FDA-approved photoplethysmograph and EKG reveal that the ring sensor is comparable to those devices in detecting beat-to-beat pulsation despite disturbances.
Banding Reduction in Electrophotographic Process Using Closed-Loop Controlled Piezoelectric Laser Beam Deflection Device
Authors: Ewe Michael T. S. , Chiu George T.-C. , Allebach Jan P. , Chan C. S. , Foote Wayne
Published: November 2021

Banding is an image artifact that appears as peroidic light and dark bands across a page. This paper presents an experimental study on the application of a piezoelectric laser beam deflection device to reduce banding in the electrophotographic process. An empirical model was obtained using system identification techniques by measuring the laser beam position on-line using an optical sensor. A closed loop control strategy is then proposed and implemented. Experiments conducted without actually printing showed significant improvements in reducing the scan line positioning errors using the proposed method.
Application of Simulated Annealing to Dexterous Object Manipulation With Multiple Agents
Authors: Vass Gabor , Payandeh Shahram , Lantos Bela
Published: November 2021

The manipulation task (called object re-configuration problem) is stated as the following: given an initial grasp of the object find the motion’s trajectories of the agents to move the object to the desired configuration. In general collision free paths for all agents must be found toward the contact points on the object (pre-grasp configuration) and the grasping and manipulation forces should then be exerted on the object by the agents. These forces are determined first to ensure a stable grasp, then to manipulate the object. We present a model based motion planner algorithm for manipulating agents for object re-configuration using simulated annealing (SA) algorithm for generating the relative motion between the object and agents. The motion of the agents relative to the object can be pure sliding, pure rolling, breaking contact and agent relocation is allowed. The motion sequence is represented by a relative velocity matrix. The algorithm can be used for example to move a known shaped object to a different position and orientation with a robotic hand. Simulation results are presented.
A Control-Oriented Engine Benchmark Model
Authors: Sivashankar N. , Boskovic D. , Friedman J.
Published: November 2021

A benchmark model is required to evaluate the performance of simulation acceleration technology and Hardware-in-the-Loop system implementations. This paper describes a six-cylinder engine model that serves this purpose. The engine model includes modeling constructs and behavior that are important for control system design and analysis. Individual cylinder torque dynamics is the core element of this model and this is described in detail. Metrics to evaluate simulation performance are also discussed.
Nonlinear Control of a Turbocharged Diesel Engine for Powertrain Control Applications
Authors: Fredriksson Jonas , Egardt Bo
Published: November 2021

This paper concerns the problem of controlling a diesel engine with a variable geometry turbine (VGT). The idea presented is to use the variable geometry of the turbine for controlling the amount of inlet air and the objective is to combine air-to-fuel ratio control with engine speed or engine torque control. The nonlinear controller is designed using so called backstepping. The control strategy seems to have a great potential, since the combustion efficiency can be kept high while reducing the turbo-lag and the emission level. The control algorithms can be extended to handle powertrain control applications. The application studied here is control of driveline oscillations.
Vibration Suppression in Turning Using a Kalman Estimator–Based Feedforward Controller
Authors: ElSinawi Ameen H. , Kashani Reza
Published: November 2021

Vibration suppression of the tool results in improved surface texture, dimensional accuracy and enhanced productivity in machining operations. The vibration of the machine tool structure, as well as the tool/workpiece interaction are the main contributors to the tool vibration. In light of this, abating the tool vibration can be approached by isolating the tool from the machine structure in the presence of a random process representing the tool/workpiece interaction. An active tool holder capable of isolating the cutting tool from the vibration of the machine tool structure is constructed. Vibration isolation is accomplished by means of a novel, Kalman estimator–based control strategy, a high bandwidth magnetostrictive actuator, and two accelerometers. The proposed control technique focuses on lowering the transmitted force to the tool that is subject to the machine structure vibration (base excitation) in presence of cutting process disturbance. The important aspect of this control strategy is that, while it is designed based on a full order model of the plant, its implementation is reduced to the realization of a second order estimator irrespective of the order of the plant model. Machining experiments showed that up to 30% improvement in surface roughness of the workpiece has been achieved using the proposed technique.
Lapping Control of Hard Disk Drive Heads: Part I—Modeling
Authors: Mei Youping , Stelson Kim A.
Published: November 2021

Bar lapping is a key process in fabricating computer hard disk drive heads. The purpose is to remove a small amount of material in a way that minimizes the stripe height variation across the bar. This article presents the first part of this study: establishing a method of simulating the material removal process. The Preston model is identified to be a reasonable constitutive relationship relating lapping rate to pressure and relative velocity. A pressure estimation method is established based on the modified beam on elastic foundation model (MBOEF) to incorporate the effect of surface shape. Simulation is conducted based on the proposed constitutive relationship and MBOEF. Results show good agreement with production observations. Hence the simulation model can serve as a tool to identify the structure of the lapping control model in the second part of this study.
An Object-Oriented Approach to Basic Mechanics
Authors: Auslander David M.
Published: November 2021

An approach is suggested for a methodology associated with basic mechanics that greatly enlarges the scope of problems accessible to students and professionals. A numerical approach based on Newtonian point-mass mechanics and pseudo-rigid bodies brings problems such as three-dimensional dynamics and constrained motions into the arena of basic mechanics. Because solutions of almost any problems of interest require computation, integrated study of physics, math, and computation is essential. An object-oriented computational approach is extremely useful since all models can be expressed with the same set of basic elements.
A Simulation-Based Synthesis Method for Engineering Systems That Contain Active Elements
Authors: Connolly Thomas J. , Longoria Raul G.
Published: November 2021

Model-based simulation makes extensive use of a growing number of analysis tools that facilitate the design cycle, especially for complex systems. Changes to a model either to increase fidelity (more complex) or to investigate design modifications can be accomplished using a synthesis methodology. An automated or semi-automated approach can be a valuable tool in system design by providing a designer with feasible strategies, while ruling out others.

This paper explores the use of classical synthesis techniques developed for electrical network theory, with particular interest to systems containing active elements. Active elements imply power flow into a system, and in many cases active devices can provide weight savings, simplify a design that contains only passive elements, or even introduce cost savings. This methodology is proposed for guiding the design of systems with actuators, for example, or for systems in which it is desired to replace existing passive components with one or more active elements (active retrofits). The synthesis method is combined with numerical simulation to generate an operating envelope for active devices. The method yields recommended physical realizations, and detailed modeling will lead to more refined system development.
Laser-Based Depth Recovery for Fine Positioning of a Microrobot
Authors: Buerkle Axel , Fatikow Sergej
Published: November 2021

There is an increasing interest in performing assembly of microsystems (i.e. non-destructive transportation, precise manipulation, and exact positioning of microcomponents) by flexible microrobots. A microrobot-based microassembly desktop station is being developed at the University of Karlsruhe. Several prototypes of piezoelectric driven microrobots and a design of the flexible microassembly desktop station were already presented. In this paper, new implementation results of a computer vision based automatic control system of a mobile microrobot with an integrated flexible manipulator are discussed. The operations of the robot manipulator take place under a microscope equipped with a CCD-camera. A major drawback of this system is its lack of depth information. For this reason, the sensor system has been enhanced by a line laser, using laser triangulation. The set-up of the modified sensor system is described. The measuring principle is based on a method called sheet of light triangulation, a variation of standard triangulation. This approach is described in detail; its advantages and limitations are discussed.
Prototyping Millirobots Using Dextrous Microassembly and Folding
Authors: Shimada E. , Thompson J. A. , Yan J. , Wood R. , Fearing R. S.
Published: November 2021

This paper discusses two processes for rapidly prototyping micromechanical systems: first microassembly, and second, laser cutting of thin sheets and folding. Sub-millimeter rigid blocks can be dextrously manipulated using two 1 DOF fingers and an XYZ micro-positioning stage. Algorithms for micro-part manipulation use open-loop compliant grasps combined with slip to align microparts, which can then be adhesively bonded. Strong, lightweight structures with low friction flexural joints can be readily laser cut, then folded. Potentially, thermally driven actuators can be simply integrated with flexural structures to build fingers for part manipulation.
Effects of Physical Bandwidth on Perception of Virtual Gratings
Authors: Wall Steven A. , Harwin William S.
Published: November 2021

When exploring a virtual environment using a point interaction type force feedback interface, users are forced to adopt a method of “temporal encoding” in order to classify textured surfaces, due to the lack of spatially distributed cues on the fingerpad. Dynamic modelling of haptic interfaces suggests that high spatial frequency information may be attenuated, such that discrimination of stimuli by human users is restricted by the performance of the device. Subjects were asked to judge the orientation of virtual gratings, using a conventional PHANToM interface and one augmented with a dedicated high frequency actuated end-effector. A significant increase in discrimination performance was found for the higher bandwidth interface.
Roughness Perception of Haptically Displayed Fractal Surfaces
Authors: Costa Michael A. , Cutkosky Mark R.
Published: November 2021

Surface profiles were generated by a fractal algorithm and haptically rendered on a force feedback joystick. Subjects were asked to use the joystick to explore pairs of surfaces and report to the experimenter which of the surfaces they felt was rougher. Surfaces were characterized by their root mean square (RMS) amplitude and their fractal dimension. The most important factor affecting the perceived roughness of the fractal surfaces was the RMS amplitude of the surface. When comparing surfaces of fractal dimension 1.2–1.35 it was found that the fractal dimension was negatively correlated with perceived roughness.
Frequency Dependence of Compliance Contrast Detection
Authors: Dhruv Neel , Tendick Frank
Published: November 2021

Psychophysical experiments were performed to investigate the haptic perception of objects with varying compliance over their surfaces. Perception of compliance contrast is important in interaction with soft environments, as in teleoperative surgery. Simulated surfaces were presented using a haptic interface in virtual environments. An adaptive 2–down, 1–up procedure was used to determine thresholds for compliance contrast detection at a range of spatial frequencies. The maximum effective temporal frequencies of compliance change, due to the subjects’ action of scanning the surfaces, were calculated. Force contrast detection thresholds were determined at a range of temporal frequencies to investigate the reliance of compliance contrast detection on force cues. Compliance and force discrimination thresholds were determined in order to compare with low frequency contrast thresholds. Compliance and force contrast detection thresholds were found to be 2% and 1% above 1/2 cyc/cm and 20 Hz, respectively. Both were significantly smaller than respective compliance and force discrimination thresholds and low frequency contrast detection thresholds. It appears that the improvement in compliance contrast detection sensitivity is due to subjects being more sensitive to force contrast at higher temporal frequencies. By changing environment exploration strategies or limb impedance, subjects may be able to change their sensitivity to object compliance contrast.
Time Delay Compensation and Stability Issues in Teleoperation
Authors: Caradima Carmen M. , Wang David W.
Published: November 2021

The stability of teleoperation over the Internet is a growing research area. The unknown time delays of the data transmission, however, compromise performance and stability. It is assumed in this work that force information is not available which is the case for most commercial haptic devices. This paper examines two approaches to this challenging problem. The first approach focuses on using Kalman filters to predict, at the local haptic device, the present state of the remote haptic device. In this way, the time delays can be made to seem as if they did not exist. Simulation results are presented on experimental data to verify this technique. The second approach is to employ haptic devices which are mechanically designed to have linear dynamics. It is shown that our proposed feedback configuration is stable for all gains, up to a maximum time delay which can be precomputed. Experimental results are presented.
Fatigue Properties of Cu-Cr In-Situ Composite
Authors: Masuda Chitoshi , Tanaka Yoshihisa
Published: November 2021

The new electrical conductive material, Cu-15wt%Cr in-situ composite, was developed for the application of lead frame, high field magnet and trolley wire. The Cu-Cr composite was fabricated by casting method in vacuum and forged, solution-treated, and cold drawn (η = 4.66 and 6.94). In this paper the cold drawn Cu-Cr composite was tested under cyclic loading at room temperature in comparison to the data for pure copper. The fatigue stresses decreased with increasing the number of cycles to failure and the double -knees were not seen on the S-N curves for both alloys as in other face centered cubic materials such as aluminum alloys and high strength steels, such as spring steels and carburized steels. The fatigue strength of Cu-Cr composite is double that for pure copper. The fatigue strength of Cu-Cr composite with cold drawing at η = 6.94 is higher than that at η = 4.66 tested under an axial loading (R = 0.1). On the fatigue fracture surface, the fatigue crack initiated from the un-dissolved chromium particle situated beneath the specimen surface and the crack direction was changed along the chromium fiber. In order to improve the fatigue strength of Cu-Cr composite it is very important that the size and amount of un-dissolved chromium particles would be reduced.
Numerical Analysis of the Mechanical Behaviors of Bolted Joint Under Thermal Load
Authors: Fukuoka Toshimichi , Xu Quantuo , Yoshida Kentaro
Published: November 2021

A bolted joint is frequently used in practical applications under thermal load, such as in internal combustion engines, steam and gas turbines, pressure vessels, etc. In order to accurately evaluate the thermal stresses thus produced, the effects of thermal contact resistance at the interface and the heat flow through small gaps, which exist around the bolted joint, must be taken into account. An empirical equation for the thermal contact co-efficient at the interface composed of similar materials was presented in a previous paper. In this study, the thermal contact coefficient is measured for the case of dissimilar materials using the same procedure. Further, a simple equation for apparent thermal contact coefficient is proposed to calculate the amount of heat flow through small gaps. By incorporating the effects of such contact resistance into the finite element formulation, thermal behaviors of a bolted joint with typical configuration are to be analyzed as elastic contact problems in the transient temperature field. It is shown that among various factors, coefficient of linear expansion has a dominant effect on the variations of bolt stress.
Aliasing Effects on Nodal Acceleration Output From Nonlinear Finite Element Simulations
Authors: Neal Mark O. , Lin Chin-Hsu , Wang J. T.
Published: November 2021

Nodal acceleration output from nonlinear finite element crash simulations often contains high frequency components. If this output is not sampled frequently enough the high frequency components will be aliased and the resulting acceleration output will be inaccurate. It is recommended in this paper that a low-pass filter be installed in the crashworthiness finite element codes which would remove the high frequency components of the nodal accelerations before they are sampled for output. This would completely eliminate aliasing error in acceleration output. Prior to this installation, there are several options for reducing the effects of aliasing on acceleration output. One option is to request very high sampling rates for acceleration output; however this will result in very large output files. Another option is to calculate the accelerations by differentiating the output velocities. This option, which effectively is an averaging filter acting on the accelerations, is available in the finite element code DYNA3D. The properties of this filter are examined in this paper and it is shown that this filter is very effective in reducing the effects of aliasing on acceleration output, although it should not be expected to completely eliminate potential aliasing problems. Finally, guidelines are presented for selecting nodes and sampling rates based on local natural frequencies that will reduce the effect of aliasing of the acceleration output.
Study of Aortic Ruptures Using a Finite Element Model
Authors: Zhang Ning , Yang King H.
Published: November 2021

A three-dimensional finite element model of the human thorax has been developed to study the mechanism of aortic rupture due to blunt impacts. The model has been validated against data from pendulum tests in both frontal and lateral directions. Effective stresses of the aortic inner wall were predicted in four different regions that are most likely to rupture. The aortic isthmus, clinically the most frequently ruptured site, was found to have the highest magnitude of stress among four locations in both frontal and side impact simulations. It is hypothesized that bending of the aortic arch posteriorly and stretching of the aortic arch laterally lead to biaxial tension at the aortic isthmus during blunt impact, which may help to explain the mechanism of injury in aortic ruptures.
A Biomechanical Evaluation of Anterior Cruciate Ligament Reconstruction in Response to Rotational Loads
Authors: Zeminski Jennifer , Kanamori Akihiro , Yagi Masayoshi , Debski Richard E. , Fu Freddie H. , Woo Savio L.-Y.
Published: November 2021

A successful reconstruction of the anterior cruciate ligament (ACL) after its injury should restore the kinematics of the intact knee, as well as reproduce the in-situ force in this ligament. While ACL reconstruction has been successful to limit anterior tibial translation under anterior loads applied to the tibia (1, 2), the same cannot be said about more complex loading conditions that include valgus and internal tibial torques.
On the Calculation of Fluid Shear Stresses at the Wall of Dilated Large Arteries: Part II—Application to 3D Computational Models
Authors: Finol Ender A. , Amon Cristina H.
Published: November 2021

Experimental and numerical investigations of pulsatile flows in artery models have been numerous during the last two decades. For 3D artery models, numerical predictions of wall shear stresses can be rather difficult to make due to the six independent stress tensor components that may be evaluated at any particular time during the blood flow pulse. The only 3D numerical study of blood flow in Abdominal Aortic Aneurysms (AAAs) known to the authors is that of Taylor and Yamaguchi (1994), in which iso-shear stress contours are reported for an asymmetric aneurysm model. However, the projection of these stresses at the aneurysm wall is not reported. This paper presents an extension of the plane stress formulation outlined in Part I, combined with a transformation of the stress tensor, as an alternative procedure for the calculation of wall shear stresses in 3D dilated artery models, with application to asymmetric aneurysms.
A Paradigm for Functional Tissue Engineering
Authors: Butler David L.
Published: November 2021

Clinicians, biologists, and engineers face difficult challenges in engineering effective, cell-based composites for repair of orthopaedic and cardiovascular tissues. Whether repairing articular cartilage, bone, or blood vessel, the demands placed on the surgical implants can threaten the long-term success of the procedure. In 1998, the US National Committee on Biomechanics addressed this problem by suggesting a new paradigm for tissue engineering called “functional tissue engineering” or FTE. FTE seeks to address several important questions. What are the biomechanical demands placed upon the normal tissue and hence the tissue engineered implant after surgery? What parameters should a tissue engineer design into the implant before surgery? And what biomechanical parameters should the tissue engineer track to determine if the resulting repair is successful? To illustrate the principles, this presentation will discuss tendon repair as a model system for functional tissue engineering.
Engineered Alignment in Arteries and Valves Fabricated From Cell-Contracted Biopolymers
Authors: Tranquillo Robert T. , Neidert Michael R.
Published: November 2021

While mechanical and bioprosthetic heart valves (mhv and bhv) have made a dramatic impact since their introduction in the 1960’s, the 10 year mortality after replacement is 30–55%, with reoperation rates of 2–4%/year because of mechanical failure (mhv), bleeding and thromboembolic complications (mhv and bhv), and calcification (bhv). Autografts and allografts, while more successful, fall far short in supply. The need is particularly great for juveniles since neither mhv nor bhv have the capacity to grow. Thus, there is great interest in developing a new generation of tissue engineered heart valves (Anderson, 1995).
Biaxial Mechanical Behavior of Aneurysmal and Nonaneurysmal Human Abdominal Aorta: Preliminary Results
Authors: Vorp David A. , Sacks Michael S. , Schiro Brian J. , Makaroun Michel S.
Published: November 2021

Rupture of abdominal aortic aneurysm (AAA) is currently the 13th leading cause of death in the US and represents a mechanical failure of the diseased aortic wall. Therefore, accurate estimation of the wall stress distribution in AAA may be a clinically useful tool to predict their risk of rupture [1]. A necessary precursor to an accurate stress analysis is an appropriate representation of the constitutive behavior of the AAA wall. Many previous biomechanical analyses of AAA have employed a linearly elastic constitutive behavior [2,3]. However, we have shown that the AAA wall is nonlinearly elastic [4] and undergoes large strain in-vivo [5]. With this as motivation, we recently developed an isotropic, nonlinearly elastic, large strain constitutive model for AAA wall based on uniaxial tensile testing data [6]. The assumption of isotropy was not validated, however. Utilization of an isotropic material symmetry in models of anisotropic structures may lead to significant errors in stress distribution [7]. Indeed, experiments suggest that the nonaneurysmal aorta is anisotropic (orthotropic) [8,9], but the material symmetry of AAA is not presently known. Moreover, most of the previous work investigating the material symmetry of aorta has been performed on animal tissue. To evaluate the anisotropy of aortic tissue, biaxial experimentation is necessary. There has been very little published work involving the biaxial experimentation of human aortic tissue, and none for AAA tissue. We present here a preliminary evaluation of the biaxial mechanical behavior of human aneurysmal and nonaneurysmal abdominal aorta.
Vertebral Motions During Flexion-Distraction Treatment for Low Back Pain
Authors: Gudavalli M. R. , Cox J. M. , Cramer G. D. , Baker J. A. , Patwardhan A. G.
Published: November 2021

This paper presents kinematics data of spinal motion during a low back treatment procedure known as flexion-distraction procedure. In this procedure the patient is positioned in a prone position on a specially developed table, and the doctor of chiropractic applies manual loads and motions with the assistance of the table to create traction and flexion effects at the joint of interest (Most often L5-S1 and L4-L5). A total of nine unembalmed cadavers were used for this study. The motions were measured using OPTOTRAK a three-dimensional optoelectronic motion measuring system. Infrared markers were attached to rods that were inserted into the L4, L5, and S1 vertebrae. The relative motions were computed using in-house developed computer software. The results showed that the vertebral motions were created at each of the joints creating flexion and traction motions as the major components. The other motions were small compared to flexion and axial translation.
Motion of the Meniscus During Passive Knee Flexion Predicted by a 3D Finite Element Model Based on MR Imaging
Authors: Zhang Heng , Totterman Saara M. S. , Perucchio Renato , Lerner Amy L.
Published: November 2021

A complete understanding of joint kinematics is important to the study of general locomotion, the diagnosis of abnormal joint behavior resulting from disease or injury, the quantitative assessment of treatment and the design of better prosthetic devices. The knee motion during passive flexion or specific activities, such as walking, running and stair climbing, has been studied to understand the knee kinematics. However, in most investigations the kinematic joint behavior was averaged over a range of specimens or subjects. Very few studies have been done to focus on the kinematics of an individual joint and its meniscus. The goal of our study is to explore the derivation of knee motion from magnetic resonance (MR) imaging data and to predict the kinematic behavior of the normal meniscus under passive knee flexion by finite element modeling.
Pressure Increases Inert Particle Uptake in Human Saphenous Vein
Authors: MacLennan M. J. , Leavitt B. J. , Schmoker J. D. , Chesler N. C.
Published: November 2021

Cardiovascular disease is one of the leading causes of death in the United States, and coronary artery bypass graft surgery (CABG) is one of the mainstays of treatment for this disease (Niklason et al., 1999). Since artificial vascular grafts suitable for coronary bypass are not yet available, the autologous internal mammary artery (IMA) and saphenous vein are used to bypass diseased tissue (Niklason et al., 1999). While IMA grafts have high long-term patency rates, a saphenous vein grafted into the arterial position tends to stenose and eventually thrombose.
Dynamic Padding Comparison
Authors: Bish Jack , Friedman Keith , Khadilkar Anil V. , Sances Anthony
Published: November 2021

Studies were conducted with 3.4 to 6.7 m/s 5th percentile female Hybrid III head drops on approximately 2.5 cm thick air gap padding, Simpson roll bar padding and a commercially available padded brush bar. The addition of padding gave up to 78% reduction in HIC (Head Injury Criterion) and 72% reduction in angular acceleration when compared to an unpadded vehicle brush bar.
Effects of Front Seat Performance Failure on Rear Seat Occupant Injuries in Rear Impacts
Authors: Friedman Keith , Kenney Tim , Bish Jack , Atesmen Kemal
Published: November 2021

An analysis of rear end accidents involving rear seat occupants seated behind a front seat occupant was conducted examining the probability of serious injury as a function of both crash severity and front seat performance failure. Seat performance failure is when some element of the seat fails to do what it is designed to do, e.g. a seat back lock allows the seat back to move during the collision. The results suggest that the risk of serious injury is greater in the 6.7-11.2 m/s Delta-V crash severity range when the seat in front of the occupant suffers a performance failure.
Stability of Isthmic Spondylolisthesis: Finite Element Model Study
Authors: Natarajan R. N. , Garretson R. B. , An H. , Andersson G. B. J.
Published: November 2021

Spondylolysis is a developmental condition or a stress fracture phenomenon, in which a defect in the pars interarticularis leads to varying degrees of instability in the lumbar spine. A finite element model was used to study the effect of pars defect as well as pars defect combined with varying slip on the change in flexibility of the lumbar motion segments under mechanical loading. Compared to the intact model, a pars defect at L3–L4 level allowed a small increase in motion at L2 with respect to L5 under all loading modes except torsion. Motion of L2 with respect to L5 was further increased by 3% to 20% with 50% translation prior to loading in all loading modes except torsion. Fifty percent translation increased the torsion motion further by 50%. In every model, the increase in motion was greatest under torsion. This study showed that stability of a motion segment in spondylolysis depends on the amount of spondylolisthesis and the loading condition. There was more motion with increased slip in all-loading modes with largest increase with torsion moment load. The type of loading also affects the degree of motion, with torsion creating significant instability.
Probabilistic High Cycle Fatigue Analysis of Turbine Engine Components
Authors: Cesare Mark A. , Sues Robert H.
Published: November 2021

This paper presents the three step approach to computing the probability of high cycle fatigue in turbine engine components that has been implemented in the ProFES probabilistic finite element software. The first step is to develop a probabilistic Campbell Diagram for mode interaction screening. The probabilistic diagram is developed considering uncertainties in material properties, boundary conditions, geometry, and operating conditions. This approach is an improvement over the deterministic approach as the closeness of a mode to an operating frequency can be measured in a probabilistic sense and gives engineers the capability to answer questions of the type, “What is the probability that modes interact within 5Hz over the lifetime of the engine.” The second step is to perform a probabilistic dynamic analysis. This step is done for interactions that are deemed critical from the step one analysis. The actual structural response is determined and the probability of exceeding a critical level is determined. The third step applies a cumulative damage model to the stress distributions from step two to find the fatigue failure probability. This step is applied for modes that are found to be critical in the step two analysis. The complete process is automated using the ProFES probabilistic finite element software which allows pre and post processing of the FEM model to be integrated into one probabilistic analysis.
Damage Mechanisms in Plasma-Sprayed Alumina Coatings
Authors: Trice Rodney W. , Prine David W. , Faber Katherine T.
Published: November 2021

Al2O3 coatings produced by plasma spray have been considered for wear resistance and corrosion protection. Mechanical investigations of these coatings are often performed when the coating is still on the metallic substrate, hiding the intrinsic response of the coatings and the lamellae that make up their microstructure. The development of a compression test for stand-alone coatings will be described. Cyclic compression loading with monotonically increased peak stresses was employed to study the deformation and damage of the coatings. Transmission electron microscopy and acoustic emission were also used to identify damage mechanisms that ultimately lead to failure. It is proposed that numerous defects that exist in plasma-sprayed coatings, including porosity and microcracks, serve as sites for crack nucleation and/or propagation. As these small cracks extend subcritically under an applied stress that ultimately propagate parallel to the loading direction along inter-lamella boundaries. With increasing stress, these cracks ultimately link resulting in catastrophic failure.
Flow Characteristics of a Rotating Disk in Surfactant Solutions
Authors: Ogata Satoshi , Watanabe Keizo
Published: November 2021

Recently, considerable interest has developed in surfactant additives for use in district heating and cooling systems to lower the pumping energy requirement. Many studies in the case of surfactant solutions have been done for the flow behavior in a circular pipe. However, few studies have been conducted on flow near a rotating disk in surfactant solutions. In this paper, the flow characteristics near an enclosed rotating disk in surfactant solutions were studied by applying flow visualization techniques and analyzed by applying the momentum integral equations which are related to the three boundary layer problem. The test surfactant solution was Ethoquad 0/12 with sodium salicylate at a concentration of 200ppm and a temperature of 18°C. The flow patterns were obtained at Re = 2.5×105 and 3.5×105 so that the Reynolds number range corresponds with the transition region to turbulent flow in the boundary layer on the rotating disk for Newtonian fluids. Consequently, it has been clarified that the amplitude of the circular vortex on the rotating disk was reduced and the flow direction near the disk was turned outward to the circumferential direction comparing with that of tap water. In additional, the limiting maximum drag reduction asymptote for a moment coefficient of a rotating disk was obtained by applying the momentum integral equation for drag-reducing solutions based on previous papers on circular pipe flow.
Handling Several Sugars at a Time: a Case Study of Xyloglucan Utilization by
Ruminiclostridium cellulolyticum
Authors: Kampik Clara , Liu Nian , Mroueh Mohamed , Franche Nathalie , Borne Romain , Denis Yann , Gagnot Séverine , Tardif Chantal , Pagès Sandrine , Perret Stéphanie , Vita Nicolas , de Philip Pascale , Fierobe Henri-Pierre
Published: November 2021

The study of the decomposition of recalcitrant plant biomass is of great interest as the limiting step of terrestrial carbon cycle and to produce plant-derived valuable chemicals and energy. While extracellular cellulose degradation and catabolism have been studied in detail, few publications describe the complete metabolism of hemicelluloses and, to date, the published models are limited to the extracellular degradation and sequential entry of simple sugars.
Dual-site blood culture yield and time to positivity in neonatal late-onset sepsis
Authors: Coggins Sarah A , Harris Mary Catherine , Srinivasan Lakshmi
Published: November 2021

Objective

To determine whether culture yield and time to positivity (TTP) differ between peripheral and central vascular catheter-derived blood cultures (BCx) in neonatal intensive care unit (NICU) patients evaluated for late-onset sepsis.

Design

Single-centre, retrospective, observational study.

Setting

Level IV NICU.

Participants

The study included infants >72 hours old admitted to NICU in 2007–2019 with culture-confirmed bacteraemia. All episodes had simultaneous BCx drawn from a peripheral site and a vascular catheter (‘catheter culture’).

Main outcome measures

Dual-site culture yield and TTP.

Results

Among 179 episodes of late-onset bacteraemia (among 167 infants) with concurrently drawn peripheral and catheter BCx, the majority (67%, 120 of 179) were positive from both sites, compared with 17% (30 of 179) with positive catheter cultures only and 16% (29 of 179) with positive peripheral cultures only. 66% (19 of 29) of episodes with only positive peripheral BCx grew coagulase-negativeStaphylococcus, while 34% (10 of 29) were recognised bacterial pathogens. Among 120 episodes with both peripheral and catheter BCx growth, catheter cultures demonstrated bacterial growth prior to paired peripheral cultures in 78% of episodes (93 of 120, p<0.001). The median TTP was significantly shorter in catheter compared with peripheral cultures (15.0 hours vs 16.8 hours, p<0.001). The median elapsed time between paired catheter and peripheral culture growth was 1.3 hours.

Conclusion

Concurrently drawn peripheral and catheter BCx had similar yield. While a majority of episodes demonstrated dual-site BCx growth, a small but important minority of episodes grew virulent pathogens from either culture site alone. While dual-site culture practices may be useful, clinicians should balance the gain in sensitivity of bacteraemia detection against additive contamination risk.
Mapping the national evidence on double burden of malnutrition in Ethiopia: a protocol of scoping review
Authors: Getacher Lemma , Ademe Beyene Wondafrash , Belachew Tefera
Published: November 2021

Introduction

Currently, the double burden of malnutrition (DBM) is an emerging public health problem due to the inevitable consequences of nutritional transition. An increasing number of studies have reported the DBM in Ethiopian populations. However, organised and summarised national evidence is not yet available. Therefore, the main aim and research question of this scoping review is to map the national evidence on the DBM in the last decades in Ethiopia.

Methods

This scoping review will be mapping the national evidence on the DBM in different population groups of Ethiopia including all ages and both sexes from 1 January 2021 to 30 September 2021. TheJoanna Briggs Institute Reviewer’s Manualwill be used as the methodology of review for this review. The search strategy will be conducted using electronic databases such as PubMed, ScienceDirect, Cochrane Library, Wiley Online Library, Google Scholar, and grey literature sources and reference lists of key studies to identify studies appropriate for inclusion in the review. Two independent reviewers will be screened independently with all abstracts and full-text studies for inclusion. Data will be abstracted into tables and logically organised according to the items addressed in the specific research questions.

Ethics and dissemination

The data will be used from publicly available secondary sources. Therefore, no ethical review and approval will be required for this review. Dissemination of results will be sought through peer-reviewed publications, conference presentations and stakeholder meetings. Regarding registration, this review protocol is registered on the figshare website on 28 February 2021, with the DOI numberhttps://doiorg/106084/m9figshare14131874.
Assessing preferences for leisure activities of people receiving adult day services: a study protocol for concept mapping and psychometric testing
Authors: Rommerskirch-Manietta Mike , Purwins Daniel , Van Haitsma Kimberly , Abbott Katherine , Rodrigues-Recchia Daniela , Roes Martina
Published: November 2021

Introduction

Leisure activities appear to be an important factor in maintaining and improving health in old age. To better understand what people want to do when visiting an adult day service (ADS), it is important to systematically assess their preferences. Currently, there is no instrument for assessing preferences for leisure activities for people receiving ADS. Accordingly, the planned study aims to develop or modify and psychometrically test an instrument to assess leisure activities preferences for use with people receiving ADS.

Methods and analysis

A mixed-method design with a participatory research approach was chosen for this study (Preferences for Everyday Living-Deutschland, PELI-D II). In the first step of this study, leisure activities will be identified on the basis of an evidence map. In the second step, the results from the evidence map will be empirically supplemented, and leisure activities will be categorised and prioritised within a concept mapping approach by people who receive ADS. Subsequently, based on this categorisation, either an instrument that was piloted in a previous study (PELI-D I) will be modified or an instrument with a focus on preferences for leisure activities in ADS will be explored. In the last step of this study, the instrument will be psychometrically tested. Data will be analysed via content analysis as well as descriptive and inferential statistics and statistical tests. The results will be presented in various tables and graphs (eg, pattern matching).

Ethics and dissemination

This study was approved by the ethics committee of the Witten/Herdecke University (application number 226/2020). The results will be made available to the public at (inter)national conferences, in peer-reviewed articles and in articles for practitioners.
Defining CD4 T helper and T regulatory cell endotypes of progressive and remitting pulmonary sarcoidosis (BRITE): protocol for a US-based, multicentre, longitudinal observational bronchoscopy study
Authors: Koth Laura L , Harmacek Laura D , White Elizabeth K , Arger Nicholas Kostandinos , Powers Linda , Werner Brenda R , Magallon Roman E , Grewal Pineet , Barkes Briana Q , Li Li , Gillespie May , Collins Sarah E , Cardenas Jessica , Chen Edward S , Maier Lisa A , Leach Sonia M , O’Connor Brian P , Hamzeh Nabeel Y
Published: November 2021

Introduction

Sarcoidosis is a multiorgan granulomatous disorder thought to be triggered and influenced by gene–environment interactions. Sarcoidosis affects 45–300/100 000 individuals in the USA and has an increasing mortality rate. The greatest gap in knowledge about sarcoidosis pathobiology is a lack of understanding about the underlying immunological mechanisms driving progressive pulmonary disease. The objective of this study is to define the lung-specific and blood-specific longitudinal changes in the adaptive immune response and their relationship to progressive and non-progressive pulmonary outcomes in patients with recently diagnosed sarcoidosis.

Methods and analysis

The BRonchoscopy at Initial sarcoidosis diagnosis Targeting longitudinal Endpoints study is a US-based, NIH-sponsored longitudinal blood and bronchoscopy study. Enrolment will occur over four centres with a target sample size of 80 eligible participants within 18 months of tissue diagnosis. Participants will undergo six study visits over 18 months. In addition to serial measurement of lung function, symptom surveys and chest X-rays, participants will undergo collection of blood and two bronchoscopies with bronchoalveolar lavage separated by 6 months. Freshly processed samples will be stained and flow-sorted for isolation of CD4 +T helper (Th1, Th17.0 and Th17.1) and T regulatory cell immune populations, followed by next-generation RNA sequencing. We will construct bioinformatic tools using this gene expression to define sarcoidosis endotypes that associate with progressive and non-progressive pulmonary disease outcomes and validate the tools using an independent cohort.

Ethics and dissemination

The study protocol has been approved by the Institutional Review Boards at National Jewish Hospital (IRB# HS-3118), University of Iowa (IRB# 201801750), Johns Hopkins University (IRB# 00149513) and University of California, San Francisco (IRB# 17-23432). All participants will be required to provide written informed consent. Findings will be disseminated via journal publications, scientific conferences, patient advocacy group online content and social media platforms.