bluuebunny/crossref_metadata_2025_split huggingface dataset:
On Influence Coefficients and Nonlinearity for Thin Shells of Revolution
Authors: Reissner Eric 
Published: June 2021

Abstract
The paper is concerned with a nonlinear formulation of the problem of rotationally symmetric deformations of thin elastic shells of revolution, which are acted upon by edge forces and moments. Determined are, in particular, nonlinear corrections to the known results of the linear theory, for edge displacements and rotations. The calculations are for cases for which thickness and curvature of the shell are such as to insure that stresses and deformations are effectively contained within a narrow edge zone of the shell.
A Differential Stress-Strain Relation for the Hexagonal Close-Packed Array of Elastic Spheres
Authors: Duffy J. 
Published: June 2021

Abstract
A differential stress-strain relation is derived for a medium composed of a hexagonal close-packed array of elastic spheres in contact. The stress-strain relation is based on the theory of elastic bodies in contact, and includes the effects of both normal and tangential components of contact forces. Results of an experiment performed as a test of the differential stress-strain relation are presented.
A Mathematical Model Depicting the Stress-Strain Diagram and the Hysteresis Loop
Authors: Whiteman I. R. 
Published: June 2021

Abstract
A model is made up of elastoplastic elements, all of which have the same value of Young’s modulus E, but which have different values of yield stress. It is shown that the dimensionless tangent modulus graph Et/E represents the cumulative frequency distribution of those elements which are in the elastic region. From the frequency distribution, the equations for the stress-strain diagram and the hysteresis loop can be written.
Theory of Flight of the Sounding Rocket
Authors: Liu V. C. 
Published: June 2021

Abstract
Solutions of the equations of motion of vertically ascending rockets (both in power flight and in free flight) are given in closed form. Atmospheric density is assumed to vary exponentially with altitude, and the variation of the drag coefficient of the rocket with Mach number is assumed to follow a definite pattern. (The validity of the latter assumption is established by its close agreement with measured results.) These solutions, given in terms of special transcendental functions, can be used for the rapid estimation of sounding-rocket performance, eliminating the often-used laborious process of stepwise integration. The general rocket-performance parameters prescribed in the analysis also can be used to advantage in comparing and selecting multistage sounding rockets.
Unsteady Laminar Boundary Layers Over an Arbitrary Cylinder With Heat Transfer in an Incompressible Flow
Authors: Yang Kwang-Tzu 
Published: June 2021

Abstract
A method is presented for calculating the development of momentum and thermal laminar boundary layers on a heated cylinder of arbitrary shape when the cylinder moves in an incompressible fluid at rest with an unsteady velocity. This analysis is based on solutions to the unsteady momentum and energy-integral equations in conjunction with a set of universal functions, derived from exact solutions to the boundary-layer equations for a specific unsteady problem. These universal functions are given in tabulated form. Those associated with the energy-integral equation are calculated with a Prandtl number of 0.7. The reliability and limitation of these functions are indicated and discussed in the light of several simple problems of which solutions are available. A detailed calculation procedure for the general unsteady problem is given and then followed by a numerical example.
Strain-Hardening Solutions to Plate Problems
Authors: Perrone Nicholas , Hodge P. G. 
Published: June 2021

Abstract
Two sets of strain-hardening flow laws based on an analogy with a kinematic model are derived for circular plates made of an initially Tresca material. The two sets of flow laws, called complete and direct hardening, differ in the point at which the plane-stress assumption is introduced. The complete-hardening flow laws are more consistent since the plane-stress assumption is made at the latest possible stage in their derivation. Complete and direct-hardening solutions are obtained to each of three different plate problems. The results indicate that the direct-hardening solutions give a fair approximation to the complete-hardening ones.
Dynamic Loading Tests of an Aircraft-Type Beam
Authors: Ripperger E. A. , Barton W. R. 
Published: June 2021

Abstract
Experimental tests were conducted to determine the failure characteristics of simplified box-type wing structures loaded dynamically, as compared to those of similar beams loaded statically. It was found that under dynamic loading, of the type applied, failure occurred at essentially the same loads and deflections observed at failure under static loading conditions. Tip deflections and accelerations were calculated using the force-deflection relationship determined by static loading, and compared to measured values. Agreement between measured and calculated values was only fair.
Extensional Vibrations of Elastic Plates
Authors: Mindlin R. D. , Medick M. A. 
Published: June 2021

Abstract
A system of approximate, two-dimensional equations of extensional motion of isotropic, elastic plates is derived. The equations take into account the coupling between extensional, symmetric thickness-stretch and symmetric thickness-shear modes and also include two face-shear modes. The spectrum of frequencies for real, imaginary, and complex wave numbers in an infinite plate is explored in detail and compared with the corresponding solution of the three-dimensional equations.
Effect of Acoustic Streaming on Heat Transfer of Porous Composite Phase Change Material by Using Lattice Boltzmann Simulation
Authors: Li Xiangxuan , Li Xinyi , Cui Wei , Ma Ting , Lu Lin , Wang Qiuwang 
Published: June 2021

AbstractIn this paper, the lattice Boltzmann (LB) method was used to simulate the flow and heat transfer process in porous composite phase change material (PCM) with acoustic streaming, to investigate the mechanism of heat transfer enhancement caused by acoustic streaming. The study focused on the effect of acoustic streaming at different Rayleigh number, Prandtl number, amplitude and wavelength of acoustic streaming on the flow field, temperature field, liquid fraction field, and average Nusselt number at the hot wall. The results show that acoustic streaming can enhance the fluid flow in the liquid phase region, and reduce the temperature inhomogeneity and inclination of liquid–solid interface front. The natural convection and the forced convection caused by acoustic streaming both get strengthened with the increasing of Rayleigh number, thus the influence of acoustic streaming first slightly rises and then drops. The momentum diffuses slower compared to the heat diffusion with the increasing of Prandtl number, thus the influence of acoustic streaming increases. With the amplitude of acoustic streaming increasing, the effect of acoustic streaming has a more remarkable inhibiting effect on average liquid fraction, decreasing by 1.11%, 5.09%, and 20.1% at the amplitude of acoustic streaming δρ* = 0.005, 0.01, 0.02, respectively. The average temperature and average liquid fraction show no obvious differences with the increasing of the wavelength of the acoustic streaming.
Development and Processing of Thermal-Hydraulic Model for GFR 2400 Fast Reactor Design and NESTLE Coupled Transient Code
Authors: Osuský Filip , Vrban Branislav , Čerba Štefan , Lüley Jakub , Nečas Vladimír 
Published: June 2021

Abstract
The paper investigates the influence of the used thermal-hydraulic approximations on the coupled calculations of gas-cooled fast reactor design (hereby GFR 2400). The NESTLE code is used as coupled simulation tool and solves the multigroup neutron diffusion equation by the finite difference method that is internally coupled with a thermal-hydraulic subchannel code. The in-house developed tempin code and the computational fluid dynamics (CFD) code fluent (from ANSYS code system, Canonsburg, PA) are used to prepare the thermal-hydraulic data for the GFR 2400 calculations. The tempin code solves the steady-state heat balance equation with flowing coolant in triangular lattice cell together with temperature dependent thermal-hydraulic properties of the fuel, cladding, and coolant. Based on the calculated fuel bundle temperature distributions by the tempin code, the thermal-hydraulic material properties (approximations) suitable for the NESTLE coupled code are processed for the GFR 2400 design. The influence of the constant and radial heat generation term within the fuel pin is studied within the paper. The performance of the NESTLE code with thermal-hydraulic approximations processed by both (tempin and fluent) methods is compared with the findings of the GoFastR project. Moreover, both the thermal-hydraulic approximations were compared for one steady-state and one transient state, related to the rapid withdrawal of one control rod assembly from the core. Changes in thermal-hydraulic distributions are described and visualized in the paper.
Effects of Sweep, Dihedral and Skew on Aerodynamic Performance of Low-Pressure Axial Fans With Small Hub-to-Tip Diameter Ratio
Authors: Wang Jie , Kruyt Niels P. 
Published: June 2021

Abstract
Axial fans with a small hub-to-tip diameter ratio are used in many branches of industry. Optimization of their aerodynamic performance is important, for which using sweep, dihedral, and skew of the blades' stacking line form an important method. Investigations on axial fans with medium to high hub-to-tip diameter ratio have shown that forward sweep of blades can give an improved aerodynamic performance, especially the total-to-total efficiency. However, only a few studies for fans with a small hub-to-tip diameter ratio have been reported. For such fans, extensive regions of backflow are present behind the fan near the hub. Based on a validated computational fluid dynamics simulation method, the effects of a sweep, dihedral and skew in axial and circumferential directions (in forward and backward direction) on the aerodynamic performance of small hub-to-tip ratio fans are investigated, with a linear stacking line. Current results show that forward sweep and circumferential skew are beneficial for higher total-to-total efficiency and that higher total-to-static efficiency can be obtained by forward dihedral and axial skew. The backward shape variety generally gives negative aerodynamic effects. Forward sweep and circumferential skew shorten the radial migration path, but more flow separation is present near the hub. With forward dihedral and axial skew, the backflow region is reduced in size and axial extent, but a more significant hub corner stall region is found. The pressure reduction due to sweep and dihedral is more limited than what could be expected from wing aerodynamics.
Fractal Properties of a Falling Particle Curtain in Air
Authors: Ludwigsen Josh , Wayne Patrick , Freelong Daniel , Vigil Gregory , Shaheen Carolina , Vorobeiff Peter , Truman C. Randall 
Published: June 2021

Abstract
The formation of a gravity-driven falling particle curtain is important for many problems, including solar tower particle receivers and setting the correct initial conditions for modeling shock interaction with multiphase media. One important characteristic of the curtain is the time history of its fractal dimension that characterizes the evolutionary growth of perturbations along the curtain's extent. For multiphase flows, fractal dimension can be used to help predict the types of instabilities that will occur within the flow. Our experiment aimed to establish the transient and stationary-value fractal dimension of a dense particle curtain with varying thickness containing particles with a density of 1.44 gm/cm3 and nominal diameter of 40 μm. High-speed video of the curtain was captured and analyzed. This data from this experiment, besides providing insights into the relevant physical processes, will be used to validate numerical models for multiphase flows.
An Analysis of the Secondary Flow Around a Tandem Blade Under the Presence of a Tip Gap in a High-Speed Linear Compressor Cascade
Authors: Konrath Liesbeth , Peitsch Dieter , Heinrich Alexander 
Published: June 2021

Abstract
Tandem blades have often been under investigation, experimentally as well as numerically, but most of the studies have been about tandem blade stators without tip gap. This work analyzes the influence of a tip gap on the flow field of a tandem blade for engine core compressors. Experiments have been conducted in a high-speed linear compressor cascade on a tandem and a reference geometry. The flow is analyzed using five-hole probe measurements in the wake of the blades and oil flow visualization to show the near surface stream lines. First, the results for design conditions (tandem and conventional blades) are compared to measurements on corresponding blades without a tip gap. Similarities and differences in the flow topology due to the tip clearance are analyzed, showing that the introduction of the tip clearance has a similar influence on the loss and turning development for the tandem and the conventional blades. The tandem blade features two tip clearance vortices with a complex flow interaction and the possible formation of a third counter-rotating vortex between them. An incidence variation from 0 deg to 5 deg for both blades indicates at first a similar behavior. After a separation of the flow field into gap and non-gap half, it becomes apparent that the tandem blade shows higher losses on the gap side, while featuring a close-to-constant behavior on the non-gap side. Further investigation of the flow on the gap side shows indicators of the front blade exhibiting tip clearance vortex break down, while the rear blade seems unaffected.
A tale of two Tweefonteins: What physical correlation, geochronology, magnetic polarity stratigraphy, and palynology reveal about the end-Permian terrestrial extinction paradigm in South Africa
Authors: Gastaldo Robert A. , Neveling Johann , Geissman John W. , Kamo Sandra L. , Looy Cindy V. 
Published: June 2021

Abstract
The contact between the Daptocephalus to Lystrosaurus declivis (previously Lystrosaurus) Assemblage Zones (AZs) described from continental deposits of the Karoo Basin was commonly interpreted to represent an extinction crisis associated with the end-Permian mass-extinction event at ca. 251.901 ± 0.024 Ma. This terrestrial extinction model is based on several sections in the Eastern Cape and Free State Provinces of South Africa. Here, new stratigraphic and paleontologic data are presented for the Eastern Cape Province, in geochronologic and magnetostratigraphic context, wherein lithologic and biologic changes are assessed over a physically correlated stratigraphy exceeding 4.5 km in distance. Spatial variation in lithofacies demonstrates the gradational nature of lithostratigraphic boundaries and depositional trends. This pattern is mimicked by the distribution of vertebrates assigned to the Daptocephalus and L. declivis AZs where diagnostic taxa of each co-occur as lateral equivalents in landscapes dominated by a Glossopteris flora. High-precision U-Pb zircon (chemical abrasion-isotope dilution-thermal ionization mass spectrometry) age results indicate maximum Changhsingian depositional dates that can be used as approximate tie points in our stratigraphic framework, which is supported by a magnetic polarity stratigraphy. The coeval nature of diagnostic pre- and post-extinction vertebrate taxa demonstrates that the L. declivis AZ did not replace the Daptocephalus AZ stratigraphically, that a biotic crisis and turnover likely is absent, and a reevaluation is required for the utilization of these biozones here and globally. Based on our data set, we propose a multidisciplinary approach to correlate the classic Upper Permian localities of the Eastern Cape Province with the Free State Province localities, which demonstrates their time-transgressive nature.
Femtochemistry of Rhodopsins
Authors: Ostrovsky M. A. , Nadtochenko V. A. 
Published: June 2021

Abstract
The review considers the spectral kinetic data obtained by us by femtosecond absorption laser spectroscopy for the photochromic reaction of retinal isomerization in animal rhodopsin (type II), namely, bovine visual rhodopsin and microbial rhodopsins (type I), such as Exiguobacterium sibiricum rhodopsin and Halobacterium salinarum bacteriorhodopsin. It is shown that the elementary act of the photoreaction of retinal isomerization in type I and type II rhodopsins can be interpreted as a transition through a conical intersection with retention of the coherence of the vibrational wave packets generated during excitation. The coherent nature of the reaction is most pronounced in visual rhodopsin as a result of the barrier-free movement along the excited surface of potential energy, which also leads to an extremely high rate of retinal isomerization compared to microbial rhodopsins. Differences in the dynamics of photochemical reactions of type I and type II rhodopsins can be related to both differences in the initial isomeric forms of their chromophores (all-trans and 11-cis retinal, respectively), as well as with the effect of the protein environment on the chromophore. Despite the practically identical values of the quantum yields of the direct photoreaction of visual rhodopsin and bacteriorhodopsin, the reverse photoreaction of visual rhodopsin is much less effective (φ = 0.15) than in the case of bacteriorhodopsin (φ = 0.81). It can be assumed that the photobiological mechanism for converting light into an information process in the evolutionarily younger visual rhodopsins (type II rhodopsins) should be more reliable than the mechanism for converting light into a photoenergetic process in the evolutionarily more ancient microbial rhodopsins (type I rhodopsins). The low value of the quantum yield of the reverse reaction of visual rhodopsin can be considered as an increase in the reliability of the forward reaction, which triggers the process of phototransduction.
Parent-reported health status of preterm survivors in a Canadian cohort
Authors: Ghotra Satvinder , Feeny David , Barr Ronald , Yang Junmin , Saigal Saroj , Vincer Michael , Afifi Jehier , Shah Prakeshkumar S , Lee Shoo K , Synnes Anne R 
Published: June 2021

ObjectivesHealth status (HS)/ health-related quality of life measures, completed by self or proxy, are important outcome indicators. Most HS literature on children born preterm includes adolescents and adults with limited data at preschool age. This study aimed to describe parent-reported HS in a large national cohort of extreme preterm children at preschool age and to identify clinical and sociodemographic variables associated with HS.MethodsInfants born before 29 weeks’ gestation between 2009 and 2011 were enrolled in a prospective longitudinal national cohort study through the Canadian Neonatal Network (CNN) and the Canadian Neonatal Follow-Up Network (CNFUN). HS, at 36 months’ corrected age (CA), was measured with the Health Status Classification System for Pre-School Children tool completed by parents. Information about HS predictors was extracted from the CNN and CNFUN databases.ResultsOf 811 children included, there were 79, 309 and 423 participants in 23–24, 25–26 and 27–28 weeks’ gestational age groups, respectively. At 36 months’ CA, 78% had a parent-reported health concern, mild in >50% and severe in 7%. Most affected HS attributes were speech (52.1%) and self-care (41.4%). Independent predictors of HS included substance use during pregnancy, infant male sex, Score for Neonatal Acute Physiology-II, bronchopulmonary dysplasia, severe retinopathy of prematurity, caregiver employment and single caregiver.ConclusionMost parents expressed no or mild health concerns for their children at 36 months’ CA. Factors associated with health concerns included initial severity of illness, complications of prematurity and social factors.
Extubation generates lung volume inhomogeneity in preterm infants
Authors: Bhatia Risha , Carlisle Hazel R , Armstrong Ruth K , Kamlin C Omar Farouk , Davis Peter G , Tingay David G 
Published: June 2021

ObjectiveTo evaluate the feasibility of electrical impedance tomography (EIT) to describe the regional tidal ventilation (VT) and change in end-expiratory lung volume (EELV) patterns in preterm infants during the process of extubation from invasive to non-invasive respiratory support.DesignProspective observational study.SettingSingle-centre tertiary neonatal intensive care unit.PatientsPreterm infants born <32 weeks’ gestation who were being extubated to nasal continuous positive airway pressure as per clinician discretion.InterventionsEIT measurements were taken in supine infants during elective extubation from synchronised positive pressure ventilation (SIPPV) before extubation, during and then at 2 and 20 min after commencing nasal continuous positive applied pressure (nCPAP). Extubation and pressure settings were determined by clinicians.Main outcome measuresGlobal and regional ΔEELV and ΔVT, heart rate, respiratory rate and oxygen saturation were measured throughout.ResultsThirty infants of median (range) 2 (1, 21) days were extubated to a median (range) CPAP 7 (6, 8) cm H2O. SpO2/FiO2 ratio was a mean (95% CI) 50 (35, 65) lower 20 min after nCPAP compared with SIPPV. EELV was lower at all points after extubation compared with SIPPV, and EELV loss was primarily in the ventral lung (p=0.04). VT was increased immediately after extubation, especially in the central and ventral regions of the lung, but the application of nCPAP returned VT to pre-extubation patterns.ConclusionsEIT was able to describe the complex lung conditions occurring during extubation to nCPAP, specifically lung volume loss and greater use of the dorsal lung. EIT may have a role in guiding peri-extubation respiratory support.
Postoperative complications in glaucoma surgery: literature review-based recommendations to improve reporting consistency
Authors: Stringa Francesco , Kastner Alan , Heuer Dale , Barton Keith , King Anthony J 
Published: June 2021

AimsTo recommend a list of complications of glaucoma surgery to be used in future glaucoma surgery research and reporting by exploring the spectrum of complications’ names, the variety of definitions and time frames used for reporting them in glaucoma surgical trials.MethodsComplications’ names, definitions and time frames identified from a previously conducted systematic review of glaucoma surgery trials (registration number: CRD42019121226) were reviewed. Only postoperative complications were considered. Surgical techniques described in the papers from the previous systematic review were retrieved and grouped according their mechanism of action.Reviewers independently recommended each complication’s inclusion or exclusion in a list to be proposed as a potential standard for reporting in glaucoma interventions. A literature-based definition of a ‘surgical complication’ was used to inform these decisions. Recorded complication’s details were used to inform the development of clinically relevant definitions, a consensus-driven exercise between reviewers resolved disagreements.ResultsWe identified 48/111 (43.2%) of the reported complications as suitable for inclusion, of which 17 were merged into other included complications having a broader meaning making up a final table of 32 postoperative complications. For 25 of them, the authors kept ‘names’ that were previously used in the systematic review, but provided a definition that was not mentioned in these papers. Five included complications were given both ‘names’ and definitions not previously mentioned. The authors maintained the name and definition for one complication. There were 16 complications that were in common to all the procedures retrieved from the previous review.ConclusionsWe propose a table of revised names and comprehensive definitions of postoperative complications, to simplify the process of reporting complications after glaucoma surgery and to improve consistency among surgical trials.