bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational Fluid Dynamics Modeling of Fire and Human Evacuation for Nuclear Applications
Authors: Sun L. , Podila K. , Chen Q. , Bayomy A. M. , Rao Y. F. 
Published: September 2019

Abstract
The nuclear industry has seen an increased use of computational fluid dynamics (CFD) technology as a high-fidelity tool for design-basis and beyond-design-basis accident simulations. Among its applications, CFD modeling of fire and smoke propagation in confined zones (e.g., a main control room (MCR)) is a promising approach, since detailed experimental investigation under various accident scenarios would be difficult. Egress analysis considering human behaviors is of significant importance to an effective accident mitigation strategy, and high-fidelity analysis tools now encompass these parameters in the simulation and design of emergency evacuations. In this study, the fire and smoke propagation in a MCR is modeled using the large eddy simulations (LES) code fire dynamics simulator (FDS), along with an evacuation module, EVAC to simulate the emergency egress under an electrical cabinet fire scenario. The FDS results presented in this paper constitute the first step at Canadian Nuclear Laboratories (CNL) in advancing the CFD modeling of fire and evacuation for nuclear applications.
A Forward Time Stepping Heat Conduction Model for Spot Melt Additive Manufacturing
Authors: Stump B. , Plotkowski A. 
Published: September 2019

Abstract
Solidification dynamics are crucial for determining microstructure development in additively manufactured parts. Multiphysics models based on finite element or finite volume methods may help gain insight for complicated phenomena such as fluid flow, keyholing, and porosity but are too computationally expensive to use for simulating actual builds. Recent analytic and semi-analytic solutions for moving heat sources in a semi-infinite three-dimensional space provide a way to accurately estimate the solidification conditions for entire builds. The downside to these methods is that, unlike finite element or finite volume methods, they cannot use the temperature distribution of the previous timesteps to march the solution forward in time. This paper provides the mathematical formulation and implementation of a forward time stepping (FTS) approach to an existing semi-analytic solution. The speed and accuracy of the two methods are then compared for various scan patterns. The result is that, for spot melts, the forward time-stepping model provides improvements in both speed and accuracy. This is especially true for longer simulations, where the simulation can be orders of magnitude faster. The longest simulation analyzed in this paper was roughly 30× faster when using the forward time-stepping model versus the straightforward implementation of the semi-analytic solution.
Leakage and Force Coefficients of a Grooved Wet (Bubbly Liquid) Seal for Multiphase Pumps and Comparisons With Prior Test Results for a Three Wave Seal
Authors: Lu Xueliang , San Andrés Luis , Wu Tingcheng 
Published: September 2019

Abstract
In the subsea oil and gas industry, multiphase pumps and wet gas compressors are engineered choices saving transportation and separation facility costs. In these machines, seals handling multiple phase components must be able to operate without affecting the system efficiency and its dynamic stability. This paper, extending prior work conducted with uniform clearance and wavy surface annular seals, presents measurements of leakage and dynamic force coefficients in a grooved seal whose dimensions are scaled from an impeller wear ring seal in a boiler feed pump. The 14-grooves seal has diameter D = 127 mm, length L = 0.34 D, and clearance c = 0.211 mm; each groove has shallow depth dg ∼2.6 c and length Lg ∼ 3.4% L. At a shaft speed of 3.5 krpm (surface speed = 23.3 m/s), a mixture of air in ISO VG 10 oil with inlet gas volume fraction (GVF) ranging from 0 (just oil) to 0.7 (mostly air) lubricates the seal. The pressure ratio (inlet/exit) is 2.9. The flow is laminar since the liquid is viscous and the pressure drop is low. The measured mixture mass flow decreases continuously with an increase in inlet GVF. The seal stiffnesses (direct K and cross coupled k), added mass (M), and direct damping (C) coefficients are constant when the supplied mixture is low in gas content, GVF ≤ 0.1. As the gas content increases, 0.2 ≤  GVF ≤ 0.5, the seal direct dynamic stiffness becomes nil with an increase in excitation frequency, whereas k and C reduce steadily with GVF. In general, for GVF ≤ 0.5, the direct damping is invariant with frequency; variations appearing for GVF = 0.7. Compared against a three wave annular seal, the grooved seal offers much lower force coefficients, in particular the viscous damping. Thus, for laminar flow operation (heavy oil) with a low pressure drop as in a wear ring seal, a three wave seal is recommended as it also offers a significant centering stiffness.
Rotated G-Shaped Insertion to Suppress Natural Convection Inside a Square Enclosure That Has Conductive Walls
Authors: Alhazmy Majed M. 
Published: September 2019

Abstract
This paper presents the results of a numerical study for using a simple insertion to reduce the heat transfer through an air-filled square cavity when subjected to a temperature gradient. The insertion is a rectangular sheet folded in a special way to produce the shape of a rotated letter G. The insertion is thermally conductive, and in perfect contact with the walls of the cavity. The cavity has thick conductive walls. The two outer vertical sides of the cavity are isothermal, and the two horizontal sides are adiabatic. The solution of continuity, momentum, and energy equations for this system yields the isotherms, streamlines, and heat flux transported across the cavity. The insertion suppresses the convection currents inside the cavity and hence reduces the heat transfer rate across them. The analysis shows the effect of the insertion dimensions and thermal properties on the heat transfer rate through the cavity. This paper also presents the results of using this insertion inside the holes of an ordinary building brick. The insertion is an easy tool to manufacture and a simple device to use for reducing the heat transfer through the blocks. The G insertion reduces the heat flux by 27–42%.
Grasp and Orientation Control of an Object by Two Euler–Bernoulli Arms With Rolling Constraints
Authors: Endo Takahiro , Shiratani Nobuhiro , Yamaguchi Kaiyo , Matsuno Fumitoshi 
Published: September 2019

Abstract
This paper focuses on grasping and manipulation of an object by two one-link flexible arms. By taking rolling constraints between the arm tip and the grasped object, the arms have the potential to grasp and manipulate an object at the same time. To realize grasping and manipulation by two flexible arms, a boundary controller is derived from a Lyapunov functional related to the total energy of a dynamic model described by a hybrid partial differential equation-ordinary differential equation (PDE-ODE) model. The derived controller consists of the bending moment at the root of the arm, the rotational angle, and the angular velocity of the motor. In particular, the controller does not need the feedback of the information of the grasped object, and thus, it is easy to implement the controller. Further, it is shown that the derived controller realizes stable grasping and orientation control of the object as well as vibration control of the arms. Finally, experiments and numerical simulations are conducted to investigate the validity of the derived boundary controller.
A Nonlinear Integral Sliding Surface to Improve the Transient Response of a Force-Controlled Pneumatic Actuator With Long Transmission Lines
Authors: Butt Khurram , Sepehri Nariman 
Published: September 2019

AbstractA force-controlled pneumatic actuator with long connecting tubes is a well-accepted solution to develop magnetic resonance imaging (MRI)-compatible force control applications. Such an actuator represents an uncertain, second-order, nonlinear system with input delay. The integral sliding mode control, because of guaranteed robustness against matched uncertainties throughout the system response, provides a favorable option to design a robust controller for the actuator. However, if the controller is based on a linear integral sliding surface (LISS), the response of the actuator overshoots, especially when there are large initial errors. Minimizing overshoot results in a smaller controller bandwidth and a slower system response. This paper presents a novel nonlinear integral sliding surface (NLISS) for a sliding mode controller to improve the transient response of the actuator. The proposed surface is a LISS augmented by a nonlinear function of tracking error and does not have a reaching phase when there are initial errors and even multiple steps in the desired trajectory. The surface enables the integral sliding mode controller to offer variable damping, which changes from low to high as the transient error approaches small values and vice versa. Simulation studies and experimental results show that the controller based on the proposed sliding surface successfully eliminates the overshoot without compromising the controller bandwidth, rise, and settling times. For performance evaluation, the controller parameters are tuned using the globalized and bounded Nelder–Mead (GBNM) algorithm with deterministic restarts. The study also establishes the asymptotic stability of the controller based on the proposed sliding surface using Lyapunov's stability criterion.
On the Connection Between Geometry and Statically Determined Membrane Stresses in the Human Cornea
Authors: Angelillo M. , Montanino A. , Pandolfi A. 
Published: September 2019

AbstractUnder the action of the intraocular pressure (IOP), the human cornea is stressed and deforms acquiring a quasi-spherical configuration. If the stressed configuration is known, and the cornea is regarded as a membrane, disregarding flexural behaviors with an equilibrium analysis only is possible to estimate the distribution of the average stress across the thickness. In the cornea, the action of the intraocular pressure is supported by collagen fibrils, immersed into an elastin-proteoglycan matrix, and organized in a very precise architecture to provide the necessary confinement and transparency to the light. With the goal of understanding the static consequences of shape modifications due to pathological dilatation (ectasia), we present a simplified stress analysis of the human cornea modeled as a membrane. A numerical investigation over 40 patient-specific corneas (20 normal and 20 ectatic) is carried out to establish a relationship between the physiological geometry and the distribution of the membrane stresses, and to assess the possibility to obtain information on the stress state based on topographic images only. Comparative analyses reveal that, with respect to normal corneas, in ectatic corneas the pattern of the principal stress lines is modified markedly showing a deviation from the hypothetical dominant orientation of the collagen fibrils. The rotation of the principal stress with respect to the fibril orientation can be thought as responsible of the transmission of a large amount of shear stresses onto the elastin-proteoglycan matrix. The anomalous loading of the matrix could be correlated to the evolution of time-dependent shape modifications leading to ectasia.
Enhanced Accident Tolerance of Thoria-Based Nuclear Fuels
Authors: Szpunar B. , Szpunar J. A. 
Published: September 2019

Abstract
Many factors need to be investigated before alternative nuclear fuel can be adapted for service in the harsh environment of a nuclear reactor. Urania, used conventionally as a nuclear fuel, has a low thermal conductivity, which degrades with increasing stoichiometric deviation. Thoria-based fuel has been considered as an alternative fuel, since it does not oxidize and has a high melting point and higher thermal conductivity. Simulations have shown that the fuel melting observed in urania fuel rods during an accident with steam ingress should not be observed (or will be delayed) in thoria as its thermal conductivity remains high enough to dissipate excessive heat in the center of the fuel pellets. The thermal gradient also remains low and therefore thermal stress is reduced, which should improve the longevity of the fuel. Thoria also has some other desirable properties as our calculations predict a significantly higher temperature of oxygen lattice premelting than urania. Furthermore, we found that the diffusion of fission gas, e.g., helium, is strongly affected by oxygen diffusion and therefore is slower in thoria for the temperatures where the oxygen lattice premelts in urania, but not in thoria.
Improving Engagement With Biomechanics: Student Perspectives and a Professional Development Initiative
Authors: Shultz Sarah P. , Millar Sarah-Kate , Fink Philip W. , Hébert-Losier Kim , Handsfield Geoffrey , Sheerin Kelly , Wells Denny , Clarke Jenny 
Published: September 2019

Abstract
Student engagement is an essential aspect of educational environments, and this is especially true for Science, Technology, Engineering, and Mathematics (STEM) disciplines, where student engagement declines in middle and high school years. Techniques for bolstering student engagement, such as hands-on learning, may be especially effective in the field of biomechanics since this discipline is rooted in STEM and has fundamental applications to everyday movement. To this end, this paper describes (1) the perceptions of student teachers in their first year of tertiary (undergraduate) education regarding the biomechanics content from their secondary (high school) education, and (2) a professional development initiative, in the form of a discipline-specific teacher training workshop, to enhance biomechanics resources for teachers via peer networking. The perception of student teachers in their first year of tertiary education in teaching indicated a positive relationship between perception of secondary school teaching quality and self-confidence with specific biomechanical concepts. Open responses focused on the need to cover concepts thoroughly, using practical activities where possible, and taking time to ensure understanding before progressing to more advanced concepts. The teacher training workshop provided secondary school Physical Education teachers with an opportunity to network nationally with other teachers across New Zealand, and internationally with university-based biomechanics researchers. Peer focus groups helped to design and refine sets of experiential learning activities that could be easily implemented in the classroom.
An Instrumented High-Speed Rotor With Embedded Telemetry for the Continuous Spatial Pressure Profile Measurement in Gas Lubricated Bearings: A Proof of Concept
Authors: Shalash Karim , Schiffmann Jürg 
Published: September 2019

Abstract
Pressure is the constitutive quantity governing the flow field in gas lubricated bearings. Knowledge of the pressure is of principal importance in the fundamental understanding of such bearings as well as for the validation of their models. Pressure measurements can be done from the bearing side using pressure taps, yet, several details will not be captured. In order to acquire a continuous scan of the pressure field inside the bearing, it is necessary to measure from the rotor side. This paper presents an instrumented measurement high-speed rotor with embedded pressure probes and a wireless telemetry that is capable of the continuous pressure field measurement within the gas film of journal bearings. The rotor was tested on externally pressurized gas journal bearings (EPGJBs) (D = 40 mm and L/D = 1), and pressure profile measurements were acquired up to 37.5 krpm (DN 1.5 M). Measurements at discrete points using pressure taps inside the test bearing were also performed for comparison. The measurements from both sides (bearing and rotor) were in good agreement at quasi-static conditions. At higher operational speeds, it was necessary to perform an in situ system identification and calibration for the embedded pressure probes using the bearing side measurements as a reference. The in situ system identification technique was successful to reconstruct the attenuated pressure signals for a wide range of supply pressures (amplitudes) and rotor speeds (excitation frequencies). The instrumented rotor was proven qualified to perform time-resolved pressure measurements within the gas film of journal bearings up to 37.5 krpm.
Pressure Profile Measurements Within the Gas Film of Journal Foil Bearings Using an Instrumented Rotor With Telemetry
Authors: Shalash Karim , Schiffmann Jürg 
Published: September 2019

Abstract
Foil bearings are strong candidates to support oil-free turbomachinery. Although foil bearings are a widely used technology, models describing their behavior are not validated using the film pressure, which is the fundamental variable of any fluid film bearing. This paper presents pressure profiles measured within the gas film of a journal foil bearing. The pressure is measured using an instrumented rotor with embedded pressure probes and wireless telemetry. The measurements yield the simultaneous circumferential pressure profiles at two axial positions inside the bearing. Proximity probes on the bearing allowed the measurement of the corresponding rotor orbits. The bearing under investigation is a bump-type compliant journal bearing, with a nominal diameter of 40 mm, an L/D = 1, and was tested up to 37.5 krpm. Load-displacement and break-away tests were performed on the test bearing in order to identify bearing parameters necessary for reproducibility. The pressure profiles are compared to a frequency domain foil bearing model. This paper is a step toward further fundamental understanding of the foil bearing behavior and the validation of the rich modeling literature.
Mutation spectrum of the bestrophin-1 gene in a large Chinese cohort with bestrophinopathy
Authors: Gao Feng-Juan , Qi Yu-He , Hu Fang-Yuan , Wang Dan-Dan , Xu Ping , Guo Jing-Li , Li Jian-Kang , Zhang Yong-Jin , Li Wei , Chen Fang , Xu Ge-Zhi , Liu Wei , Chang Qing , Wu Ji-Hong 
Published: September 2019

BackgroundBestrophin-1 (BEST1) gene is associated with a wide range of ocular phenotypes, collectively termed as bestrophinopathy. The aim of the current study was to identify the mutation spectrum ofBEST1in a large cohort of Chinese patients with bestrophinopathy.MethodsPatients clinically suspected of bestrophinopathy were screened using multigene panel testing. AllBEST1variants were confirmed by Sanger sequencing, and validated in the families.FindingsA total of 92 patients (Best vitelliform macular dystrophy (BVMD)=77; autosomal recessive bestrophinopathy (ARB)=15) from 58 unrelated families of Chinese origin and their available family members (n=65) were recruited. Overall, 39 distinct disease-causingBEST1variants were identified, including 13 novel variants, and two reported variants but novel for ARB. Of them, 14 were associated with ARB, 23 with BVMD and two (c.604C>T and c.898G>A) with both BVMD and ARB. Most mutations associated with BVMD were missense (97.78%), while ARB was associated with more complex mutations, including missense (88.46%), splicing effect (3.85%), and frameshifts (15.38%).BEST1hotspots were c.898G>A and c.584C>T among BVMD and ARB patients, respectively. Hot regions were located in exons 8, 2 and 6 in BVMD patients, and in exons 5 and 7 in ARB patients. The overall penetrance ofBEST1in our cohort was 71.30%, no de novo mutations were identified.ConclusionThis is the largest study to date that provides major population-based data of theBEST1mutation spectrum in China. Our results can serve as a well-founded reference for genetic counselling for patients with bestrophinopathy of Chinese origin.
Disproportion of lamellar capillary non-perfusion in proliferative diabetic retinopathy on optical coherence tomography angiography
Authors: Uchitomi Daiki , Murakami Tomoaki , Dodo Yoko , Yasukura Shota , Morino Kazuya , Uji Akihito , Yoshitake Tatsuya , Fujimoto Masahiro , Tsujikawa Akitaka 
Published: September 2019

PurposeTo characterise the non-perfused areas (NPAs) in the superficial and deep capillary layers (sNPAs and dNPAs, respectively) in the posterior pole in proliferative diabetic retinopathy (PDR) on wide-field optical coherence tomography angiography (OCTA) images.MethodsWe retrospectively reviewed 104 eyes of 70 patients with PDR from whom wide-field swept source OCTA images were acquired. sNPAs and dNPAs were manually measured in each quadrant of the inner (1–3 mm diameter), intermediate (3–6 mm), and outer (6–10 mm) rings centred on the fovea. Two qualitative findings, that is,segmented NPAsandperiarteriolar NPAs, were also compared.ResultsThe dNPAs were greater than the sNPAs (p<0.001) in each subfield. The outer ring had higher rates of deep NPAs than did the intermediate ring in the superior, inferior and temporal quadrants (p=0.010, p=0.004 and p<0.001, respectively), whereas no differences were detected in the nasal quadrant (p=1.000). Similarly, sNPA rates were higher in the outer ring than in the intermediate ring in the inferior and temporal subfields (p=0.003 and p<0.001, respectively). In 45 eyes with extensive NPAs, there were modest correlations between the dNPAs in the nasal and temporal quadrants in the intermediate (ρ=0.341, p=0.026) and outer (ρ=0324, p=0.032) rings, whereas sNPAs exhibited no associations.Segmented NPAswere delineated more frequently in the superficial layer than in the deep layer (p<0.001).Periarteriolar NPAswere more frequent in the deep layer (p<0.001).ConclusionsThree-dimensional assessment of wide-field OCTA promotes a better understanding of the enigmatic disproportion of lamellar NPAs in the posterior pole in PDR.
Quality of life after in-hospital cardiopulmonary resuscitation for patients over the age of 80 years
Authors: Burden Eleanor , Pollock Lucy , Paget Camilla 
Published: September 2019

AbstractObjectivesSuccess of in-hospital resuscitation decreases with age; however, national data show that 11.3% of patients over 80 years survive to discharge. There are few published qualitative data about the quality of life for these patients postsuccessful resuscitation. We aimed to investigate postresuscitation quality of life in patients over the age of 80 through a series of case studies.MethodsAll patients over the age of 80 years, who received cardiopulmonary resuscitation (CPR) at our district general hospital in 2015–2016, were included. Success of resuscitation, survival at day 1 and to discharge were recorded. For patients who survived to 1 day and beyond, case reports were written to create individual patient stories.Results47 patients over the age of 80 years received CPR at Musgrove Park Hospital over a 2-year period. Five (10.6%) survived to discharge. Of those surviving to discharge, two had substantial functional decline, requiring discharge to nursing homes having previously been independent. Of the five families/patients who commented on their experience, only one expressed a positive view. When discussed, the majority of patients/families opted for a Do Not Attempt CPR.ConclusionOur results have shown that there is a risk of substantial functional decline associated with successful CPR in those patients over the age of 80 years. The majority of patients and relatives contacted after successful resuscitation expressed a negative view of the experience. Our study highlights the importance of having early informed discussions with patients and families about CPR in order to avoid detrimental outcomes and ensure patient wishes are correctly represented.