bluuebunny/crossref_metadata_2025 huggingface dataset:
Online Chatter Detection for Milling Operations Using LSTM Neural Networks Assisted by Motor Current Signals of Ball Screw Drives
Authors: Vashisht Rajiv Kumar , Peng Qingjin
Published: August 2020

For certain combinations of cutter spinning speeds and cutting depths in milling operations, self-excited vibrations or chatter of the milling tool are generated. The chatter deteriorates the surface finish of the workpiece and reduces the useful working life of the tool. In the past, extensive work has been reported on chatter detections based on the tool deflection and sound generated during the milling process, which is costly due to the additional sensor and circuitry required. On the other hand, the manual intervention is necessary to interpret the result. In the present research, online chatter detection based on the current signal applied to the ball screw drive (of the CNC machine) has been proposed and evaluated. There is no additional sensor required. Dynamic equations of the process are improved to simulate vibration behaviors of the milling tool during chatter conditions. The sequence of applied control signals for a particular feed rate is decided based on known physical and control parameters of the ball screw drive. The sequence of the applied control signal to the ball screw drive for a particular feed rate can be easily calculated. Hence, costly experimental data are eliminated. Long short-term memory neural networks are trained to detect the chatter based on the simulated sequence of control currents. The trained networks are then used to detect chatter, which shows 98% of accuracy in experiments.
Effects of Postweld Heat Treatment on the Phase Transformation and Mechanical Behavior of NiTi Ultrasonic Spot Welded Joints With Al Interlayer
Authors: Li Chunjie , Ao Sansan , Oliveira J. P. , Zeng Zhi , Cui Huijie , Luo Zhen
Published: August 2020

The influence of postweld heat treatments (PWHTs) on the phase transformation characteristics, microstructural evolution, and mechanical properties of ultrasonic spot welded NiTi alloy with Al interlayer was investigated. At room temperature, the as-welded joints were fully austenitic, while the microstructure of welded joint after PWHT at 450 °C consisted of a mixture of martensite and austenite. The transformation temperatures were found to increase after the PWHT. Transmission electron microscope analysis shows that Al3Ti intermetallic compounds were formed on the Al side of the Al/NiTi interface after the PWHT at 450 °C for 90 min. Furthermore, finely dispersed nanoscale Ni4Ti3 precipitates were observed in the joint. These nanoscale precipitates resulted in an increase in the transformation temperatures and improved the mechanical properties of the PWHT material. During lap shear test, the as-welded samples failed in a brittle manner in the NiTi alloy, while the PWHT samples failed in the Al interlayer and exhibited ductile-like fracture characteristics.
A Framework for Mapping and Controlling Exoskeleton Gait Patterns in Both Simulation and Real-World
Authors: Rose Lowell , Bazzocchi Michael C. F. , de Souza Connal , Vaughan-Graham Julie , Patterson Kara , Nejat Goldie
Published: August 2020

Stroke is a leading cause of disability, and robotic lower body exoskeletons have been developed to aid in gait rehabilitation. The simulation modeling and testing processes are often developed and deployed separately. This introduces additional steps which can hinder on-the-fly customization of gait patterns required for individualized gait rehabilitation. In this paper, we present a centralized control architecture which integrates both the simulated model and the exoskeleton hardware for lower body exoskeletons. The architecture allows for ease of simulating, adapting, and deploying gait patterns on an exoskeleton for use in gait rehabilitation, and allows for the on-the-fly customization and verification of gait patterns by physiotherapists during rehabilitation. Experiments validate the use of our overall control architecture to both model and control a physical exoskeleton, while following desired gait patterns.
Incremental Needle Insertion System for Force and Position Sensing
Authors: Brown Dailen , Gonzalez-Vargas Jessica M. , Han David , Miller Scarlett , Moore Jason
Published: August 2020

An Incremental Needle Insertion System (INIS) which simultaneously measures the force and position of a needle during insertion was designed and fabricated for use in a tissue deformation study to improve realism in medical simulation. The INIS was tested in a fresh frozen cadaver experiment and the position of the needle was plotted and compared to the expected needle path. It was found that the INIS is sufficiently accurate with an average path deviation of 1.55 mm. In addition, INIS was shown to successfully measure the maximum Central Venous Catheterization needle insertion force which ranged from 3.02 N to 3.73 N.
Development of Anaglyph 3D Functionality for Cost-Effective Virtual Reality Anatomical Education Tool
Authors: Deakyne Alex J. , Gaasedelen Erik , Iles Tinen , Iaizzo Paul A.
Published: August 2020

Virtual reality (VR) is becoming more widely available and accessible as a technology due to the affordability of cheap computing power. Thus, it has made it possible for virtual reality systems to capture audiences in industry and education, as well as for personal use. Currently, a major limitation of VR headsets is that the user’s vision is completely occluded, making it difficult for them to interact with others. This is problematic in an educational setting since it is difficult for the given instructor and students to have a shared learning experience. Here, we have developed anaglyph 3D functionalities into the Visible Heart® Laboratories anatomical virtual reality platform. These functionalities augment what is viewed by the virtual reality user with an anaglyph shader which in turn projects it to an external display. This allows a multitude of users to wear anaglyph “red/blue 3D glasses” and view the same anatomy as the VR instructor is viewing in 3D, but while preserving the important 3D anatomical spatial relationships.
Clubfoot Kickbar: Development of an Improved Brace for Use Following Correction of Clubfoot
Authors: Kuhl Spencer , Cook Thomas M. , Morcuende Jose , Grosland Nicole
Published: August 2020

The critical final phase of treatment for congenital talipes equinovarus, commonly referred to as clubfoot, using the Ponseti Method requires parents to use a brace in order to maintain the correct foot posture for 12–14 hours each night until four years of age. Parents have been vocal about a desire to allow their children some mobility while maintaining correct alignment for the treatment of this deformity. To that end, the University of Iowa’s medical device prototyping facility Protostudios utilizes 3D CAD design, rapid prototyping principles and state of the art 3D printers to quickly iterate upon the concept of a reciprocating brace that allows for the prescribed posture of abduction and dorsiflexion in a corrected clubfoot while allowing more mobility and higher degrees of comfort for the child. Each iteration of the design was tested for fitment with the commercially available shoe and platform system developed for the Ponseti Method of Clubfoot correction. Special attention was paid to the attachment and removal process of the brace to ensure that parents of children with the deformity would have no problem employing the brace for the prescribed frequency and duration while preventing the children from removing or destroying the brace or being pinched by its reciprocating action.
Task-Specific Assistive Device (TAD): An Accessible Technological Solution for Upper Limb Disability
Authors: Jayasree-Krishnan Veena , Ghosh Shramana , Spiegler Jack , Raghavan Preeti , Kapila Vikram
Published: August 2020

The task-specific assistive device (TAD) is a compact and portable assistive device, consisting of an actuated six-bar linkage, designed to facilitate the activity of drinking from a cup without using the hands. In this paper, we examine the effectiveness of the device in supporting patients with conditions of incomplete tetraplegia and hemiplegia by simulating disability in 17 healthy subjects. The average percentage reduction in bending angle of torso with the use of TAD was found to be 40.31% for subjects with simulated incomplete tetraplegia and 37.14% for subjects with simulated hemiplegia. Users also completed the system usability scale (SUS), indicating that the device was easy to use. The user workload, measured using the NASA task load index (NASA-TLX), was found to be minimal and the device was found to be robust through user response to a user experience questionnaire. The results of this work indicate that TAD is a promising solution for facilitating independence in a basic activity of daily living such as drinking from a cup without using the hands.
A Precise Scale-Up Method to Predict Particle Delivered Dose in a Human Respiratory System Using Rat Deposition Data: An In Silico Study
Authors: Hayati Hamideh , Feng Yu
Published: August 2020

As surrogates to human beings, rats are used occasionally to study the therapeutic impact of inhaled pulmonary drug particles in microscale. To speculate human responses from rat studies, scale-up factors are widely used to extrapolate particle lung deposition from rat to human. However, available scale-up methods are highly simplified and not accurate, because they directly use the human-to-rat ratios of body weights (RBW) or lung surface areas (RSA) as the scale-up factor. To find a precise scale-up strategy, an experimentally validated Computational Fluid-Particle Dynamics (CFPD) was employed to simulate the transport and deposition of microparticles in both human and rate respiratory systems, which encompasses the pulmonary routes from mouth/nose to airways up to Generation 17 (G17) for human and G23 for the rat. Microparticles with the same range of Stk/Fr were injected into both models with the airflow at resting conditions. Numerical results indicate that particles (with the size ranging from 1 to 13 μm for humans and 0.6 to 6 μm for rat) have similar deposition pattern (DP) and deposition fraction (DF) in both models, which are resulted from both inertial impaction and gravitational sedimentation effects. A novel correlation is proposed to predict DFs in both human and rat respiratory systems as a function of the ratio of Stokes number to Froude number (Stk/Fr). Using the correlation as the novel scale-up tool, inter-species extrapolations can be precisely done on predicting particle depositions in human respiratory systems based on the deposition data in rats obtained from animal studies.
Potential of Weight Scale Based Ballistocardiography for Identifying Orthostatic Intolerance: A Tilt Table Study
Authors: Aarotale Parshuram N. , Henriksen Stian N.
Published: August 2020

Autonomic cardiovascular control is critical in regulating blood pressure during postural transition, failure of which could lead to dizziness and fall (orthostatic intolerance). In this study, the feasibility of Ballistocardiography (BCG) for quantifying autonomic nervous system activity in relation to gold standard electrocardiogram (ECG) was tested.

Simultaneous ECG, blood pressure, photoplethysmography (PPG), and BCG were continuously acquired during 5-minutes of stand tests (before and after tilt test up to 60°) from 10 participants. Heart period was derived from ECG and BCG represented as RR and JJ intervals, respectively. Spectral analysis of heart period (both RR and JJ) was performed by calculating power distributed in low-frequency (0.04–0.15 Hz) and high-frequency (0.15–0.4 Hz) bands. Strong correlation (r > 0.87 for Pre-tilt and r > 0.97 for Post-tilt, p < 0.001) between ECG and BCG derived LF, HF, and LF/HF was observed, except for LF/HF (r > 0.63 for Pre-tilt). The Wilcoxon rank sum test revealed no difference (p > 0.10) in BCG or ECG LF, HF, and LF/HF during the two stand tests.

The findings of the study highlighted the feasibility of monitoring cardiovascular control via weight-scale BCG. Therefore, the developed system can gain utility as a portable and cost-effective system for early detection and mitigation of falls associated with autonomic dysfunction.
Electrical Inhibitor for Tocolysis
Authors: RajKumar Ashwin , Karsdon Jeffrey , Naftolin Frederick , Kapila Vikram
Published: August 2020

Preterm birth (PTB) is one of the leading causes of neonatal morbidities and mortalities. Limited methods are available to physicians for mitigating PTB, thus posing an urgent need to develop effective methods for its prevention. In prior research, a benchtop electronic uterine control device (EUCD) was developed for tocolysis through injection of current pulses. However, the benchtop version is wall tethered and constrains patients to hospitals, i.e., it is unsuitable for deployment in outpatient or home settings. This paper focuses on the development of a mechatronics-based, low-cost, battery-powered, portable, and reproducible EUCD, which is suitable for use in home and clinical environments. The developed mechatronic version is validated for electrical performance with resistive load-tests, which indicate that the mechatronic device can generate current pulses similar to the existing benchtop EUCD. Furthermore, the signals generated from the device are evaluated for repeatability using coefficient of variation (CV) analysis and the results indicate that the mechatronic version can produce repeatable frequency (1–100Hz), amplitude (1–17mA), and pulse width (1–120ms) modulated current signals. An internet of medical things (IoMT) methodology is discussed to enable seamless transition of the developed device from a clinical environment to a home-based setting for remote use by the patients.
Design of a Handheld Tissue Grasping Device to Measure Tissue Mechanical Properties In-Vivo or in a Laboratory Setting
Authors: Drahos Bradley , Safdari Amer , Malik Faizan , Smith Rebecca , Kubala Matt , Norfleet Jack , Parsey Conner , Goodwin Shikha , Kowalewski Timothy M.
Published: August 2020

With medical institutions increasing the use of medical simulators for educational purposes it is detrimental that the knowledge gap regarding tissue mechanical properties be researched further in depth. The grasper device discussed throughout this paper aims to provide researchers a handheld device capable of testing soft organs and tissue in-vivo and ex-situ in a laboratory setting. The device consists of two load cells on the inner jaws of the grasper to measure compressive force and an encoder to monitor the graspers angular position which yields tissue position and strain. Accompanying the grasper is a GUI written in Rust which is capable of data file management, and providing a 10 second live feed of load cell and encoder readings. The grasper device is currently being employed in a study testing the tissue mechanical response of porcine tissue at states ranging from in-vivo to ex-situ post freeze. The results from this test, and subsequent tests using the grasper have the capability of providing much needed knowledge regarding tissue mechanical properties to improve medical simulators and medical education as a whole.
On the Modal Analysis of Blood Flow Dynamics in Brain Aneurysms
Authors: Le Trung Bao , Akerkouch Lahcen
Published: August 2020

Complex, unstable inflow jet has been linked to aneurysm growth and rupture. However, methodologies to characterize this inflow jet have not been well established. Our previous works (Le et al., J. Biomech. Engr., 2010 and Le et al., Annals Biomedical Eng., 2013) have shown a possible transition from the stable mode (cavity) to the unstable mode (vortex ring) of this jet. We have proposed the use of a non-dimensional index called Aneurysm Number to characterize this transition (Le et al., 2013). However, the quantification of such a transition is lacking. Currently, there have no efforts in quantifying unstable flows in intracranial aneurysms, which is essential in stratifying rupture risks. In this work, the aneurysmal geometries from three patients at Sanford Health, North Dakota are reconstructed from Magnetic Resonance Angiogram and Digital Subtraction Angiogram data. Using our in-house CFD code (Virtual Flow Simulator), high-resolution flow data is obtained via numerical simulation. We perform modal analysis of blood flow dynamics for these cases using Proper Orthogonal Decomposition. Our results show that there are up to five dominant modes in the flow arising from the interaction of the incoming jet and the aneurysm dome. The spatial distribution of these modes reflect the characteristics of the inflow jet and can be used to quantify flow unsteadiness. Future works will be needed to apply the same procedure for a larger population of patients to examine its relevance in clinical practice.
Pantograph/Catenary Wear Using Multibody System Dynamic Algorithms
Authors: Daocharoenporn Siripong , Mongkolwongrojn Mongkol , Kulkarni Shubhankar , Shabana Ahmed A.
Published: August 2020

In this investigation, computational multibody systems (MBS) algorithms are used to develop detailed railroad vehicle models for the prediction of the wear resulting from the pantograph/catenary dynamic interaction. The catenary wear is predicted for different motion scenarios that include constant-speed curve negotiation, and acceleration and deceleration on a tangent (straight) track. The effect of the vehicle vibration in these different motion scenarios on the contact force is further used to study the wear rates of the contact wire. The wear model used in this investigation accounts for the electrical and the mechanical effects. The nonlinear finite element (FE) absolute nodal coordinate formulation (ANCF), which is suitable for implementation in MBS algorithms, is used to model the flexible catenary system, thereby eliminating the need for using incremental rotation procedures and co-simulation techniques. The pantograph/catenary elastic contact formulation employed in this study allows for separation between the pantograph pan-head and the contact wire, and accounts for the effect of friction due to the sliding between the pantograph pan-head and the catenary cable. The approach proposed in this investigation can be used to evaluate the electrical contact resistance, contribution of the arcing resulting from the pan-head/catenary separation, mechanical and electrical wear contributions, and effect of the pantograph mechanism uplift force on the wear rate.
Origins and Current Status of the Different Communications-Based Train Control Products
Authors: Diemunsch Kenneth , Rabindran Nagaratnam
Published: August 2020

Communications-Based Train Control (CBTC) technology is used by transit agencies in large cities to maximize the use of their infrastructure. In comparison with conventional block signal system and cab signaling system, CBTC provides the most efficient capabilities with respect to headway and throughput while being the most economical in terms of maintenance cost [1]. CBTC also provides better diagnostic capabilities compared to traditional signaling systems. It uses limited number of equipment on the trackside compared to traditional signaling systems and allows either a centralized architecture or distributed architecture. For these reasons, CBTC is now the favored system for new lines as well as most signaling system renewals.[1]

Despite widely used CBTC standards, the signaling industry is not in agreement regarding what qualifies as a CBTC system and which projects are the first “real” CBTC projects. This work describes the different CBTC vendors, their genesis, when access point based radio was first introduced (access point based radio is also referred by signaling engineers as free space propagation radio), the different consolidations with other CBTC companies, and their major projects.

From the authors’ viewpoint, it is appropriate to present the CBTC vendors by geographical areas, for instance in North America: Bombardier Transportation, Thales Rail Signaling Solutions, in Europe: Alstom Transport, Hitachi Rail, Siemens Mobility, in Asia: Beijing Traffic Control Technology, China Railway Signal and Communications, Mitsubishi Electric Corporation, and Nippon Signals.
Design and Optimization of Front-End Structure With Integrated Energy Absorption for Railway Vehicles
Authors: Liu Xiaofang , Wang Jianran , Liu Yanwen , Fang Ziwen , Zhang Yanping , Hong Haifeng
Published: August 2020

As the main energy absorbing area of a railway vehicle, the front-end structure is critical to reduce the collapse of the passenger area and increase the safety of the vehicle in case of collision. In this paper, a front-end structure with integrated energy absorbing is introduced in detail as well as the iteration process. The front-end structure is mainly composed of anti-climber, collision posts, corner posts and four kinds of crush elements including center crush elements, side crush elements, interior crush elements and head girders. The shape, dimension, position, connection and material of those components are optimized multiple times based on the finite element analysis results of various load cases. The finalized structure can provide progressive controlled collapse with energy absorbing capacity of 1.22MJ and impact force less than 4450kN. At the same time, it is capable to withstand a static longitudinal load of 1224kN and vertical load of 334kN. To validate the design and analysis, the front-end structure is manufactured and tested under impact. The crash velocity, deformation and impact force show great agreement between the simulations and test results. From the design and optimization of this front end structure, it is concluded that placing the crush elements behind the collision post is beneficial for static strength design, the energy absorbing capability can be largely increased without taking additional space by using interior crush element and the geometry of the head girders plays an critical role in balancing the force distribution and providing stable crush performance.
Railroad Tie Lateral Resistance on Open-Deck Plate Girder Bridges
Authors: Gergel John T. , Vasudevan Vishali M. , Hebdon Matthew H.
Published: August 2020

On open-deck railroad bridges, the crossties (sleepers) are directly supported by the bridge superstructure and anchored with deck tie fasteners such as hook bolts. These fasteners provide lateral resistance for the bridge ties, and in railroad bridge design, their spacing is controlled by the required lateral resistance of the ties. Currently there are no provisions to assist in the calculation of lateral resistance provided by railroad ties on open-deck bridges, and as a result there are no specific requirements for the spacing of deck tie fasteners. This has led to different design practices specific to each railroad, and inconsistent fastener spacing in existing railroad bridges.

A research plan was conducted to experimentally quantify the lateral resistance of timber crossties on open-deck plate girder bridges using different wood species and types of fasteners. Experimental tests were conducted on four different species of timber crossties (Beech, Sycamore, Southern Pine, and Oak) with three different types of fasteners (square body hook bolt, forged hook bolt, and Quick-Set Anchors). A structural test setup simulated one half of an open-deck bridge with a smooth-top steel plate girder, and hydraulic actuators to apply both vertical and horizontal load to a railroad tie specimen. The three main contributions to lateral resistance on open-deck bridges were identified as friction resistance between tie and girder due to vertical load from a truck axle, resistance from the fastener, and resistance from dapped ties bearing against the girder flange. Initial testing conducted at Virginia Tech isolated each component of lateral resistance to determine the friction coefficient between tie and girder as well as resistance from just the fastener itself. Results indicate that friction resistance varies based on the magnitude of vertical truck axle load, species of wood, and quantity of creosote preservative on the tie, while fastener resistance varies based on type of fastener and displacement of the tie. With the experimental results, a preliminary equation for calculating the overall resistance of open-deck timber crossties is developed, which allows for a recommendation of fastener spacing based on the type of fastener, wood species, and anticipated lateral loads on the structure.
Field Investigation of Broken Cut Spikes on Elastic Fasteners Using Instrumented Spikes at FAST
Authors: Gao Yin , McHenry Mike , Brice Megan , Baillargeon Jay
Published: August 2020

Elastic fasteners have been shown to reduce gage widening and decrease the potential for rail roll compared to conventional cut-spike-only systems. For this reason, elastic fastening systems have been installed in high-degree curves on many North American heavy-haul railroads. Field observations in the United States, however, have noted broken cut spikes and screw/drive spikes on this type of fastening system, especially in steep-grade, high-degree curve territories. It was found that spikes typically fracture between 1 to 1.5 inches below the top surface of the ties, making them difficult to detect by visual inspection alone. Notable recent derailments have been attributed to broken spikes as reported by Class I railroads.

Transportation Technology Center, Inc. (TTCI), as part of a joint program between the Federal Railroad Administration (FRA) and the Association of American Railroads (AAR), completed the initial phase of a study investigating the root cause of these broken cut and screw/drive spikes. Previous research under this joint program has confirmed through metallurgical investigation that material fatigue was the failure mechanism, and subsequent numerical simulation has shown that the bending stress in spikes can exceed the fatigue limit of the spike material. To further investigate the in-track loading environment of spikes, cut spikes instrumented with strain gages were installed in the high-tonnage test loop of the Facility for Accelerated Service Testing (FAST) at FRA’s Transportation Technology Center The test investigated the loading environment of spikes by considering several in-track conditions. The results showed that the load transferred to spikes during insertion and train passing could cause spike stresses higher than the fatigue limit and therefore lead to the permanent bending of spikes. Moreover, the bending moment was primarily carried by one of the four spikes from the same plate. This paper provides an overview of the development of instrumented spikes as well as the results of the in-track testing using these spikes. The findings from this study will guide future revenue service testing, for which a high-grade, high-curvature location will be considered to further investigate the broken spike issue.
Continuous Monitoring of the Wheel-Rail Contact Vertical Forces by Using a Variable Measurement Scale
Authors: Boronenko Yu. P. , Rahimov R. V. , Lafta Waail M. , Dmitriev S. V. , Belyankin A. V. , Sergeev D. A.
Published: August 2020

This paper presents a new technology of continuous measurement and recording of forces in wheel/rail contact by measuring strains in two rail cross-sections, which allows increasing the measurement accuracy. The method for processing the measurement data is proposed with a variable scale between strains and force, depending on the instantaneous position of the wheel with respect to a span between sleepers. The gage characteristics obtained by rolling a wheel over the rail between two sleepers are approximated by using Fourier series abilities and used for the assessment of wheel/rail forces. By using the suggested technology, the amount of information obtained increased 2 times.
Research on Simulation of Resilient Wheel Dynamometer
Authors: Jimin Zhang , Jingyuan Wan , Wen Li , Xujie Zhong , Hechao Zhou , Yuan Qi , Chuanlun Hou
Published: August 2020

Among many testing items of infrastructure, wheel-rail force is an important factor that causes track failure, damage, train derailment and vehicle parts damage. It is also used to evaluate the ride stability, safety and as the main basis for speed limit and speed increase. Among many methods of wheel-rail force detection, the method of wheel-rail force measurement is the most accurate and direct method of wheel-rail force measurement. The method of measuring wheel-rail interaction force using wheelset of railway locomotive and rolling stock as force sensor has the highest accuracy among all wheel-rail force measurement methods.

Force-measuring wheelset is the core sensor in the dynamic test research of railway vehicles, and its performance directly affects the evaluation results of the tested objects. Before the actual line test, it is necessary to calibrate the dynamometer wheelset on the test bench. The calibration of dynamometer wheelset is an important link in the research and application of dynamometer wheelset.

With the rapid development of rail transit in various countries and the great improvement of locomotive and rolling stock manufacturing technology, higher and higher requirements has been put forward for the performance of force-measuring wheelsets, which are mainly embodied in obtaining ideal sensitivity and linearity, minimizing cross-interference and all kinds of possible external interference, and reducing the influence of the change of the position of the action point on the measurement results. For the rigid wheelset, the calibration of the force-measuring wheelset is basically perfect from the actual production to the algorithm. The relevant countries also determine the calibration in the standard form.

At present, more and more urban rail low floor vehicles are using independent resilient wheels. The mechanical structure of the bogie with resilient wheels is complex. At the same time, because of the small diameter of the resilient wheels and the rubber layer between the wheel hoop and the wheel center, it is difficult to find the strain/stress sensitive area accurately, as well as the unique installation process, the calibration of resilient wheels is rather difficult.

This paper takes the low floor resilient wheels as the research object, and studies how to make the calibration method of high precision and suitable for the independent rotating wheels of resilient wheels and the processing and analysis of calibration data. The main research contents are as follows: the development of force-measuring wheelset which is based on the finite element simulation of a resilient wheel, stress distribution analysis, and the fabrication scheme of force-measuring wheelset which meets the requirement of test accuracy is proposed by using virtual bridge formation.
Thermal Effects on Wheel Performance Based on Twin Disc Testing
Authors: Li Dingqing , Stewart Monique
Published: August 2020

This paper presents the results and findings from a testing program conducted to investigate how temperature at the wheel-rail interface may affect wheel surface performance; i.e., development of rolling contact fatigue (RCF) and wear. Under this testing program, a twin disc test machine was used to test two different types of wheel specimens (cast and forged) under a range of temperatures (ambient to 800° F) and slip ratios from 0 to 0.75 percent. This testing program included a total of 32 tests, covering two wheel materials, four different temperatures, four slip ratios, and various traction coefficients as a ratio of longitudinal and vertical wheel/rail contact forces.
A Numerical Investigation of Laterally Loaded Steel Fin Pile Foundations
Authors: Pei Te , Qiu Tong , Laman Jeffrey A.
Published: August 2020

The present study comprehensively evaluates the improvement in lateral load-carrying capacity of steel pipe piles by adding steel plates (fins) at grade level. This configuration of steel fin pile foundations (SFPFs) is effective for applications where high lateral loads are encountered and rapid pile installation is advantageous. An integrated finite element analysis (FEA) was conducted. The FEA utilized an Abaqus model, first developed to account for the nonlinear soil-pile interaction, and then calibrated and validated against well-documented experimental and filed tests in the literature. The validated FEA model was subsequently used to conduct a parametric study to understand the effect of fin geometry on the load transfer mechanism and the response of SFPFs subjected to lateral loading at pile head. The behavior of SFPFs at different displacement levels and load levels was studied. The effect of the relative density of soil on the performance of SFPFs was also investigated. Based on the numerical simulation results, the optimal fin width for maximum improvement in lateral load-carrying capacity was suggested and the underlining mechanism affecting the efficiency of fins was explained.
Comparison of Methodologies for Finite Element Model Validation of Railroad Tank Car Side Impact Tests
Authors: Eshraghi Shaun , Carolan Michael , Perlman Benjamin , González Francisco
Published: August 2020

The U.S. Department of Transportation’s Federal Railroad Administration (FRA) has sponsored a series of full-scale dynamic shell impact tests on railroad tank cars. For each shell impact test a pre-test finite element (FE) model is created to predict the overall force-time or force-displacement histories of the impactor, puncture/non-puncture outcomes of the impacted tank shell, global motions of the tank car, internal pressures within the tank, and the energy absorbed by the tank during the impact. While qualitative comparisons (e.g. the shapes of the indentation) and quantitative comparisons (e.g. peak impact forces) have been made between tests and simulations, there are currently no standards or guidelines on how to compare the simulation results with the test results, or what measurable level of agreement would be an acceptable demonstration of model validation.

It is desirable that a framework for model validation, including well-defined criteria for comparison, be developed or adopted if FE analysis is to be used without companion full-scale shell impact testing for future tank car development. One of the challenges to developing model validation criteria and procedures for tank car shell puncture is the number of complex behaviors encountered in this problem, and the variety of approaches that could be used in simulating these behaviors. The FE models used to simulate tank car shell impacts include several complex behaviors, which increase the level of uncertainty in simulation results, including dynamic impacts, non-linear steel material behavior, two-phase (water and air) fluid-structure interaction, and contact between rigid and deformable bodies.

Approaches to model validation employed in other areas of transportation where validation procedures have been documented are applied to railroad tank car dynamic shell impact FE simulation results. This work compares and contrasts two model validation programs: Roadside Safety Verification and Validation Program (RSVVP) and Correlation and Analysis Plus (CORA). RSVVP and CORA are used to apply validation metrics and ratings specified by the National Cooperative Highway Research Program Project 22-24 (NCHRP 22-24) and ISO/TS 18571:2014 respectively. The validation methods are applied to recently-completed shell impact tests on two different types of railroad tank cars sponsored by the FRA. Additionally, this paper includes discussion on model validation difficulties unique to dynamic impacts involving puncture.
Formation and desorption of nickel hexafluoroacetylacetonate Ni(hfac)2 on a nickel oxide surface in atomic layer etching processes
Authors: Basher Abdulrahman H. , Krstić Marjan , Fink Karin , Ito Tomoko , Karahashi Kazuhiro , Wenzel Wolfgang , Hamaguchi Satoshi
Published: August 2020

Thermal atomic layer etching (ALE) of nickel (Ni) may be performed with a step of thin-layer oxidation of its surface and another step of its removal by gas-phase hexafluoroacetylacetone (hfacH) as an etchant. In this study, adsorption of hfacH and possible formation of volatile nickel hexafluoroacetylacetonate Ni(hfac)2 on a NiO surface were investigated based on the density functional theory (DFT) with more realistic surface material models than those used in the previous study [A. H. Basher et al., J. Vac. Sci. Technol. A 38, 022610 (2020)]. It has been confirmed that an hfacH molecule approaching a NiO surface deprotonates without a potential barrier and adsorbs on the surface exothermically. In addition, stable adsorption of two deprotonated hfacH molecules on a NiO (100) surface was found to occur not on a single Ni atom but over a few Ni atoms instead, which makes the formation of a Ni(hfac)2 complex on the flat surface very unlikely even at elevated temperature. However, if the surface is rough and a Ni atom protrudes from the surrounding atoms, two hexafluoroacetylacetonate anions (hfac−) can bond to the Ni atom stably, which suggests a possibility of desorption of a Ni(hfac)2 complex from the surface at elevated temperature. Given the experimentally observed fact that desorption of Ni(hfac)2 complexes typically takes place on a NiO surface at a temperature of ∼300–400 °C, our DFT calculations indicate that the surface roughness of an oxidized Ni surface facilitates the formation and desorption of organometallic complexes Ni(hfac)2, and therefore, the resulting Ni surface after ALE can be smoother than the initial surface.
Eigenfunction orthogonality for one-dimensional acoustic systems with interior or end point conditions
Authors: Maynard J. D.
Published: August 2020

Some common exercises presented in introductory acoustics courses and texts illustrate solutions involving eigenvalues and eigenfunctions. Challenging extensions of these, even for one-dimensional (1D) systems, might involve a mass or spring loading the acoustic medium at an end point or at an interior point. These problems might be extended further by requiring that some given function be expanded in a series of the eigenfunctions, but such extended problems may lead to unexpected complications in regard to eigenfunction orthogonality. In this paper, Sturm-Liouville theory is used to develop a systematic method for predetermining eigenfunction orthogonality for 1D systems loaded at end points or interior points or having properties that change with jump discontinuities.
Sound field reconstruction in rooms: Inpainting meets super-resolution
Authors: Lluís Francesc , Martínez-Nuevo Pablo , Bo Møller Martin , Ewan Shepstone Sven
Published: August 2020

In this paper, a deep-learning-based method for sound field reconstruction is proposed. The possibility to reconstruct the magnitude of the sound pressure in the frequency band 30–300 Hz for an entire room by using a very low number of irregularly distributed microphones arbitrarily arranged is shown. Moreover, the approach is agnostic to the location of the measurements in the Euclidean space. In particular, the presented approach uses a limited number of arbitrary discrete measurements of the magnitude of the sound field pressure in order to extrapolate this field to a higher-resolution grid of discrete points in space with a low computational complexity. The method is based on a U-net-like neural network with partial convolutions trained solely on simulated data, which itself is constructed from numerical simulations of Green's function across thousands of common rectangular rooms. Although extensible to three dimensions and different room shapes, the method focuses on reconstructing the two-dimensional plane of a rectangular room from measurements of the three-dimensional sound field. Experiments using simulated data together with an experimental validation in a real listening room are shown. The results suggest a performance which may exceed conventional reconstruction techniques for a low number of microphones and computational requirements.
A molecular pore spans the double membrane of the coronavirus replication organelle
Authors: Wolff Georg , Limpens Ronald W. A. L. , Zevenhoven-Dobbe Jessika C. , Laugks Ulrike , Zheng Shawn , de Jong Anja W. M. , Koning Roman I. , Agard David A. , Grünewald Kay , Koster Abraham J. , Snijder Eric J. , Bárcena Montserrat
Published: August 2020

Viral RNA exported from the coronavirus replication organelle is likely to be mediated by a crown-shaped molecular pore.
Genetic Determinants of
Salmonella
Resistance to the Biofilm-Inhibitory Effects of a Synthetic 4-Oxazolidinone Analog
Authors: Griewisch K. F. , Pierce J. G. , Elfenbein J. R.
Published: August 2020

Biofilms are resistant to killing by disinfectants and antimicrobials.
S. enterica
biofilms facilitate long-term host colonization and persistence in food processing environments. Synthetic analogs of 4-oxazolidinone natural products show promise as antibiofilm agents. Here, we show that a synthetic 4-oxazolidinone analog inhibits
Salmonella
biofilm through effects on both motility and biofilm matrix gene expression. Furthermore, we identify three genes that promote
Salmonella
resistance to the antibiofilm effects of the compound. This work provides insight into the mechanism of antibiofilm effects of a synthetic 4-oxazolidinone analog in Gram-negative bacteria and demonstrates new mechanisms of intrinsic antimicrobial resistance in
Salmonella
biofilms.
Regulatory T Cells Contribute to Resistance against Lyme Arthritis
Authors: Siebers Emily M. , Liedhegner Elizabeth S. , Lawlor Michael W. , Schell Ronald F. , Nardelli Dean T.
Published: August 2020

The symptoms of Lyme disease are caused by inflammation induced by species of the
Borrelia burgdorferi
sensu lato
complex. The various presentations of Lyme disease in the population suggest that differences exist in the intensity and regulation of the host response to the spirochete. Previous work has described correlations between the presence of regulatory T cells and recovery from Lyme arthritis. However, the effects of Foxp3-expressing CD4
+
T cells existing prior to, and during,
B. burgdorferi
infection have not been well characterized.
A Critical Role for Perivascular Cells in Amplifying Vascular Leakage Induced by Dengue Virus Nonstructural Protein 1
Authors: Cheung Yin P. , Mastrullo Valeria , Maselli Davide , Butsabong Teemapron , Madeddu Paolo , Maringer Kevin , Campagnolo Paola
Published: August 2020

The World Health Organization considers dengue one of the top 10 global public health problems. There is no specific antiviral therapy to treat dengue virus and no way of predicting which patients will develop potentially fatal severe dengue, typified by vascular leakage and circulatory shock. We show here that perivascular cells (pericytes) amplify the vascular leakage-inducing effects of the dengue viral protein NS1 through contact-independent signaling to endothelial cells. While pericytes are known to contribute to noncommunicable vascular leakage, this is the first time these cells have been implicated in the vascular effects of an infectious disease. Our findings could pave the way for new therapies and diagnostics to combat dengue and potentially other infectious vascular leakage syndromes.
Comparative Evaluations of the Pathogenesis of Candida auris Phenotypes and Candida albicans Using Clinically Relevant Murine Models of Infections
Authors: Vila Taissa , Montelongo-Jauregui Daniel , Ahmed Hussian , Puthran Taanya , Sultan Ahmed S. , Jabra-Rizk Mary Ann
Published: August 2020

The newly emerged
Candida
species
C. auris
has been associated with an exponential rise in invasive disease in health care facilities worldwide with a mortality rate approaching 60%.
C. auris
exhibits a high level of transmissibility, multidrug resistance, and persistence in hospital environments, yet little is known about its pathogenesis largely due to limited data from animal studies. We used clinically relevant murine models of infection to comparatively evaluate the host niche-specific pathogenic potential of
C. auris
and
C. albicans
. Findings demonstrated that
C. auris
adheres more avidly, forming robust biofilms on catheters implanted in mice. However, although
C. auris
adhered to oral tissue
ex vivo
, it failed to colonize the oral cavity
in vivo
. In contrast, in the intraperitoneal infection model,
C. auris
persisted longer in the peritoneal cavity and kidneys. Understanding the host-pathogen factors contributing to the rise of
C. auris
as a nosocomial pathogen is critical for controlling the spread of this species.
Cytogenetic complexity and heterogeneity in intravascular lymphoma
Authors: Fujikura Kohei , Yamashita Daisuke , Yoshida Makoto , Ishikawa Takayuki , Itoh Tomoo , Imai Yukihiro
Published: August 2020

Aims

To characterise the karyotypic abnormalities and heterogeneities in intravascular lymphoma (IVL).

Methods

G-banded karyotyping was performed on biopsy specimens from a single-centre IVL cohort comprising intravascular large B-cell lymphoma (IVLBCL, n=12) and NK/T-cell lymphoma (IVNKTCL, n=1).

Results

Five IVLBCL cases and one IVNKTCL case (total 46%) were found to have normal karyotypes, and the cytogenetic abnormalities observed in the other seven IVLBCL cases (54%) were investigated further. These seven karyotypes were uniformly complex with an average of 13 aberrations. The seven cases all had abnormalities involving chromosome 6, with 57% involving structural abnormalities at 6q13, and chromosome 8, with 43% involving abnormalities at 8p11.2. In addition, 71% had aberrations at 19q13. On average, 4.4 chromosomal gains and losses were detected per case. Cytogenetic heterogeneities were observed in six cases (86%) and tetraploidy in three cases (43%). There was no significant difference in progression-free survival (p=0.92) and overall survival (p=0.61) between the IVLBCL cases with complex and normal karyotypes.

Conclusion

Approximately half of IVLBCL cases had a highly heterogeneous pattern of karyotypes with different clonal numerical and structural chromosome aberrations.
Morphological control for molecular testing: a practical approach
Authors: Gullo Irene , Marques Ana , Pinto Regina , Cirnes Luis , Schmitt Fernando
Published: August 2020

The determination of molecular aberrations within tumours is important for diagnostic, prognostic and predictive purposes. Pathologists play a critical role in the workflow of molecular diagnostics, by assuring accurate pathological diagnosis, requesting appropriate molecular testing, selecting the adequate tissue section for molecular analysis, enriching tumour cell content by manual macrodissection and estimating the tumour cellularity. Particularly, the assessment of the malignant cell fraction within a tumour section is a key determinant for an appropriate interpretation of the molecular findings. Several factors may impact the estimation of tumour cellularity and constitute a potential pitfall for the final interpretation of the molecular analysis. Evidence suggests that the reliability of morphological control could be improved by training. The scope of this commentary is to provide the training morpho-molecular pathologists with the practical tools necessary to master microscopic morphological control for solid tumours, as well as a set of images that could serve as a training set.