bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transient and Residual Stresses in Heat-Treated Cylinders
Authors: Weiner J. H. , Huddleston J. V. 
Published: June 2021

Abstract
General equations for the computation of stress rates in solid and hollow cylinders subjected to transient temperature distributions are developed, based on the assumptions of an elastic, perfectly plastic material obeying the Tresca yield condition with Poisson ratio of one half. For most temperature distributions, it appears that these equations can be integrated only by numerical means. However, for one particular temperature distribution, equivalent to a phase transformation which occurs at a fixed temperature, it is found possible to integrate them analytically, and expressions for the transient and residual stresses are obtained in closed form. The latter results are compared with experiment and qualitative agreement noted.
A Theorem of Maximum Strain Energy
Authors: Brown E. H. 
Published: June 2021

Abstract
A new theorem for elastic structures obeying Hooke’s law is proved and enunciated as follows: If the strain energy can be expressed in terms of given external loads and the positions of points constrained to have no displacement, then the expression will have a maximum value when the positions are such as make the constraining forces zero. The theorem is generalized to allow a wider class of constraint, such as the attachment of a second, rigid structure to the elastic structure under analysis, in such a way that the two have certain displacement components in common. The principle has been applied by E. H. Mansfield to certain problems in the bending of plates.
On Supersonic Wind Tunnels With Low Free-Stream Disturbances
Authors: Morkovin M. V. 
Published: June 2021

Abstract
Measurements in supersonic wind tunnels have become almost routine in the last decade and yet little is known about the free-stream disturbances, which are present, and about the means of minimizing them. The present note outlines the problems of minimizing the mean as well as the unsteady variations of velocity and temperature and gives guidance where the trends are clear. It is found that in many wind tunnels the free-stream fluctuations are likely to be dominated by aerodynamic sound in the sense of Lighthill and by shivering Mach waves. Only conjectures can be offered on the means of minimizing the resulting sound intensity at the present time.
A Perturbation Solution of the Equations of Motion of a Gyroscope
Authors: Goodstein Robert 
Published: June 2021

Abstract
A perturbation method of solution is outlined for the nonlinear equations of motion of free and forced vibration of a two-gimbal gyro. Results are given for the term displayed in the solution which indicates that the outer gimbal of the gyro will not oscillate about its initial center position, but will acquire a steady rate of change of position.
On the Natural Modes and Their Stability in Nonlinear Two-Degree-of-Freedom Systems
Authors: Rosenberg R. M. , Atkinson C. P. 
Published: June 2021

Abstract
The natural modes of free vibrations of a symmetrical two-degree-of-freedom system are analyzed theoretically and experimentally. This system has two natural modes, one in-phase and the other out-of-phase. In contradistinction to the comparable single-degree-of-freedom system where the free vibrations are always orbitally stable, the natural modes of the symmetrical two-degree-of-freedom system are frequently unstable. The stability properties depend on two parameters and are easily deduced from a stability chart. For sufficiently small amplitudes both modes are, in general, stable. When the coupling spring is linear, both modes are always stable at all amplitudes. For other conditions, either mode may become unstable at certain amplitudes. In particular, if there is a single value of frequency and amplitude at which the system can vibrate in either mode, the out-of-phase mode experiences a change of stability. The experimental investigation has generally confirmed the theoretical predictions.
Analysis of Plane Stress in Polar Co-ordinates and With Varying Thickness
Authors: Conway H. D. 
Published: June 2021

Abstract
The biharmonic stress-function equation for plane stress in polar co-ordinates is generalized by assuming that the thickness varies with the radius. In order to make this equation tractable, the thickness is assumed to be proportional to an arbitrary power of the radius. Michell’s general solution for the constant-thickness case is then generalized for this variation of thickness. As a numerical example, the solution is given for the problem of a segmental plate bent by end couples, the constant-thickness version of this well-known problem being due to Golovin.
Coupled Torsional and Longitudinal Vibrations of a Thin Bar
Authors: Di Prima R. C. 
Published: June 2021

Abstract
The effect of pretwist on the natural frequencies of coupled torsional-longitudinal oscillations of thin bars is studied. It is found that the natural frequencies of oscillations which consist primarily of torsional motion may be considerably increased depending upon the thinness of the bar, and the amount of pretwist. The natural frequencies of oscillations which consist primarily of longitudinal motion are not significantly altered.
On the Accuracy of Some Shell Solutions
Authors: Galletly G. D. , Radok J. R. M. 
Published: June 2021

Abstract
R. B. Dingle’s method [1] for finding asymptotic solutions of ordinary differential equations of a type such as occur in the bending theory of thin shells of revolution is presented in outline. This method leads to the same results as R. E. Langer’s method [2], recently used for problems of this kind, and permits a simple analytical and less formal interpretation of the asymptotic treatment of such equations. A comparison is given of edge influence coefficients due to bending loads, obtained by use of these asymptotic solutions and numerical integration of the equilibrium equations, respectively. The particular shells investigated are of the open-crown, ellipsoidal, and negative-curvature toroidal types. The results indicate that the agreement between these solutions is satisfactory. In the presence of uniform pressure, the use of the membrane solutions for the determination of the particular integrals appears to lead to acceptable results in the case of ellipsoidal shells. However, in the case of toroidal shells, the membrane and the numerical solutions disagree significantly.
A Photoelastic Approach to Transient Stress Problems Employing Low-Modulus Materials
Authors: Dally J. W. , Riley W. F. , Durelli A. J. 
Published: June 2021

Abstract
The objective of the program discussed in this paper was to develop a method, using photoelasticity and low-modulus materials, for studying dynamic stress distributions. Early in the program a number of low-modulus materials were studied and Hysol 8705 (a urethane-rubber compound) was selected as the most promising. A complete study of its mechanical and optical properties was made under static and dynamic loadings. It was established, that Poisson’s ratio ν is independent of rate of loading, the stress fringe value fσ is independent of rate of loading for strain rates greater than 8 in/in/ sec, and both the modulus of elasticity E and the strain fringe value fϵ were dependent oil the rate of loading. The specific energy loss for the material was about 10 per cent for the stress ranges associated with photoelastic determinations. Experimental observations of photoelastic fringe patterns in a rectangular strut subjected to axial impact were made to illustrate the potential of the method. Three different end conditions were imposed on the unloaded end of the strut: (a) A free end normal to the axis; (b) a fixed end normal to the axis; and (c) a free end inclined 45 deg to the axis. For the cases where the ends were normal to the axis it was found that the fringes followed the same law of reflection as the law for stresses given by elementary wave theory.
A Heat Transfer Model for Graphene Deposition on Ni and Cu Foils in a Roll-to-Roll Plasma Chemical Vapor Deposition System
Authors: Alrefae Majed A. , Fisher Timothy S. 
Published: June 2021

Abstract
High-throughput production is a major bottleneck for integration of graphene-based technologies in existing and future applications. Here, a semi-empirical heat transfer model is developed to optimize large-scale deposition of graphene on Ni and Cu foils in a roll-to-roll (R2R) plasma chemical vapor deposition (CVD) system. Temperature distributions in Ni and Cu foils during deposition are recorded with in situ temperature measurements using near-IR optical emission spectroscopy. The model indicates that foil movement significantly affects the temperature distribution and the cooling rate of the foil. Consequently, graphene growth on Cu is limited to lower web speeds for which the foil temperature is higher, and the residence time in the plasma is longer. On the other hand, graphene can be deposited on Ni at relatively higher web speeds due to moderately high diffusion rate of carbon in Ni and increased cooling rates up to 20 K/s with higher web speed. Critical limitations in the production rates of graphene using R2R CVD process exist due to significant effects of web speed on the temperature distribution of the substrate. The thermal analysis approach reported here is expected to aid in enhancing the throughput of graphene production in R2R CVD systems.
Investigation of Fiber-Driven Mechanical Behavior of Human and Porcine Bladder Tissue Tested Under Identical Conditions
Authors: Tuttle Tyler G. , Morhardt Duncan R. , Poli Andrea A. , Park John M. , Arruda Ellen M. , Roccabianca Sara 
Published: June 2021

Abstract
The urinary bladder is a highly dynamic organ that undergoes large deformations several times per day. Mechanical characteristics of the tissue are crucial in determining the function and dysfunction of the organ. Yet, literature reporting on the mechanical properties of human bladder tissue is scarce and, at times, contradictory. In this study, we focused on mechanically testing tissue from both human and pig bladders using identical protocols to validate the use of pigs as a model for the human bladder. Furthermore, we tested the effect of two treatments on tissue mechanical properties. Namely, elastase to digest elastin fibers, and oxybutynin to reduce smooth muscle cell spasticity. Additionally, mechanical properties based on the anatomical direction of testing were evaluated. We implemented two different material models to aid in the interpretation of the experimental results. We found that human tissue behaves similarly to pig tissue at high deformations (collagen-dominated behavior) while we detected differences between the species at low deformations (amorphous matrix-dominated behavior). Our results also suggest that elastin could play a role in determining the behavior of the fiber network. Finally, we confirmed the anisotropy of the tissue, which reached higher stresses in the transverse direction when compared to the longitudinal direction.
Simulation of a Simplified Aeroengine Bearing Chamber Using a Fully Coupled Two-Way Eulerian Thin Film/Discrete Phase Approach Part II: Droplet Behavior in the Chamber
Authors: Nicoli Andrew , Johnson Kathy , Jefferson-Loveday Richard 
Published: June 2021

Abstract
Within aeroengines, bearing chambers exhibit a highly complex two-phase environment as a result of the complex air/oil interactions. The desire to operate at both higher temperatures and shaft speeds requires a sufficient understanding of these systems for design optimization. Typically, bearings are used to support the radial and axial loads transmitted by the shafts and require oil for lubrication and cooling. These bearings are housed in bearing chambers that are sealed using airblown seals. Efficient scavenging systems ensure that the oil is collected and returned to the tank avoiding any unnecessary working of the oil. Previous work at the Gas Turbine and Transmissions Research Center (G2TRC) has highlighted the need for an adequate computational model which can appropriately model the oil shedding behavior from such bearings. Oil can breakup forming droplets and ligaments, subsequently forming thin and thick films driven by both gravity and shear. The objective of this paper is to explore the modeling capability of fully two-way coupled Eulerian thin film/discrete phase models (ETFM-DPM) applied to our simplified bearing chamber configuration. The models are created using openfoam and two-way coupling is employed, enabling Lagrangian droplets to either impinge on the film surface or be removed through effects such as film stripping, splashing, or edge separation. This paper focuses on the droplets, presenting statistics relating to size, velocity, impingement, and residence time, and provides insight into solution sensitivity to operational parameters including shaft speed and oil flow rate. This extends upon our previously published work and improves bearing chamber modeling capability.
Progressive Visual Occlusion and Postural Control Responses in Individuals With and Without Chronic Ankle Instability
Authors: VanDeMark Lilly H. , Vander Vegt Christina B. , Ford Cassie B. , Mihalik Jason P. , Wikstrom Erik A. 
Published: June 2021

Context: Prophylactic and rehabilitative balance training is needed to maximize postural control and develop appropriate sensory organization strategies. Partially occluding vision during functional exercise may promote appropriate sensory organization strategies, but little is known about the influence of partially occluded vision on postural control in those with and without a history of musculoskeletal injury. Objective: To determine the effect of increasing levels of visual occlusion on postural control in a heterogeneous sample of those with and without chronic ankle instability (CAI). The secondary objective was to explore postural control responses to increasing levels of visual occlusion among those with unilateral and bilateral CAI relative to uninjured controls. Design: Cross-sectional. Setting: Sports medicine research laboratory. Patients or Other Participants: Twenty-five participants with unilateral CAI, 10 with bilateral CAI, and 16 participants with no history of lower extremity injury. Main Outcome Measures: All participants completed four 3-minute postural control assessments in double-limb stance under the following 4 visual conditions: (1) eyes open, (2) low occlusion, (3) high occlusion, and (4) eyes closed. Low- and high-occlusion conditions were produced using stroboscopic eyewear. Postural control outcomes included time-to-boundary minima means in the anteroposterior (TTB-AP) and mediolateral directions (TTB-ML). Repeated-measures analysis of variances tested the effects of visual condition on TTB-AP and TTB-ML. Results: Postural control under the eyes-open condition was significantly better (ie, higher) than the limited visual occlusion and eyes-closed conditions (P < .001) for TTB-AP and TTB-ML. For TTB-AP only, partially occluded vision resulted in better postural control than the eyes-closed condition (P ≤ .003). Conclusions: Partial and complete visual occlusion impaired postural control during dual-limb stance in a heterogeneous sample of those with and without CAI. Stroboscopic eyewear appears to induce postural control impairments to the same extent as complete visual occlusion in the mediolateral direction.
Influence of Heating Modes of Compacted Samples from Nickel Powders with Nanosized Particles on Their Interaction with Air
Authors: Alymov M. I. , Seplyarskii B. S. , Vadchenko S. G. , Zelensky V. A. , Rubtsov N. M. , Kochetkov R. A. , Shchukin A. S. , Kovalev I. D. 
Published: June 2021

Abstract
In this paper, we study compact samples of pyrophoric nickel powders with the average particle size of 85 nm, obtained by the chemical-metallurgical method. For the first time, it is experimentally shown that it is possible to passivate compact samples with a diameter of 3 mm from pyrophoric nickel powders with nanosized particles in air. For a relative density of 0.4 to 0.5, the passivation time is only 3–5 s. According to the X-ray phase analysis data, only the Ni phase is observed in passivated samples. It is found that passivated samples retain their thermal stability in air upon slow (<10 deg/s) heating to ~200°C, which is an important parameter for fire safety when handling nanopowders. The electron microscopic analysis of the passivated samples did not reveal traces of sintering of nickel nanoparticles, including after checking for thermal stability. The uniform distribution of oxygen over the passivated samples according to the data of energy dispersive analysis (the standard deviation is 0.9 at %) indicates the volumetric nature of the interaction of the samples with air during passivation. For the obtained passivated samples, the critical heating conditions were determined, under which self-ignition occurs, which is in agreement with N.N. Semyonov’s classical theory of thermal explosion.
Cost-effectiveness of a self-management and comprehensive training intervention in patients with type 2 diabetes up to 5 years of diagnosis in a specialized hospital in Mexico City
Authors: Hernández-Jiménez Sergio , García-Ulloa Ana Cristina , Anaya Pablo , Gasca-Pineda Ricardo , Sánchez-Trujillo Luis Arturo , Peña Baca Héctor , González-Pier Eduardo , Graue-Hernández Enrique O , Aguilar-Salinas Carlos Alberto , Gómez-Pérez Franciso Javier , Kershenobich-Stalnikowitz David 
Published: June 2021

IntroductionTo assess the cost-effectiveness of a multidisciplinary and comprehensive innovative diabetes care program (CAIPaDi) versus usual treatment in public health institutions.Research design and methodsUsing a cost-effectiveness analysis, we compared the CAIPaDi program versus usual treatment given in Mexican public health institutions. The analysis was based on the IQVIA Core Diabetes Model, a validated simulation model used to estimate long-term clinical outcomes. Data were prospectively obtained from the CAIPaDi program and from public databases and published papers. Health outcomes were expressed in terms of life-years gained and quality-adjusted life years (QALYs). Health and economic outcomes were estimated from a public perspective and discounted at 5% per year over a 20-year horizon. Costs are reported in US dollars (US$) of 2019. A probabilistic sensitivity analysis was performed using life-years gained and QALYs.ResultsThe CAIPaDi costs on average US$559 (95% CI: −$879 to −$239) less than the usual treatment (95% CI: −$879 to −$239) and produced a difference in mean life-years gained (0.48, 95% CI: 0.45 to 0.52) and mean QALYs (1.43, 95% CI: 1.40 to 1.46). The cost-effectiveness ratio resulted in a saving per life-year gained of −US$1155 (95% CI: −$1962 to −$460). Mean differences in QALYs resulted in a saving per QALY of −US$735 (95% CI: −$1193 to −$305). Probabilistic sensitivity analysis proved the results are robust on both life-years gained and QALYs.ConclusionsCAIPaDi has a better cost-effectiveness ratio than the usual therapy in Mexican public health institutions.
Depression and anxiety symptoms to COVID-19 outbreak among the public, medical staff and patients during the initial phase of the pandemic: an online questionnaire survey by a WeChat Mini Program
Authors: Wang Xianglan , Tao Jiong , Zhu Qi , Wu Xiuhua , Li Tong , Zhao Chongbang , Yang Weirui , Wang Xiaoying , Zhang Jinbei , Guan Nianhong 
Published: June 2021

ObjectivesTo survey anxiety and depression symptoms to COVID-19 outbreak in the public, medical staff and patients during the initial phase of the pandemic.DesignCross-sectional online survey administered through WeChat Mini Program using Chinese versions of Zung Self-rating Depression Scale and Zung Self-rating Anxiety Scale.SettingGuangzhou, China.Participants47 378 public, 1512 medical staff and 125 patients with COVID-19.ResultsHigher rates of depression (47.8%) and anxiety symptoms (48.7%) were shown by patients who were screened positive compared with those of the public (35.6%, 25.7%) or medical staff (15.4%, 13.3%). The professional identity of a nurse, conditions of ‘with an infected family member’ and ‘working at the frontline’ were risk factors to depression or anxiety symptoms for the medical staff. Younger age, lower educational level, female and not having adequate masks were the risk factors for the public.ConclusionThe COVID-19 outbreak increased people’s depression or anxiety emotion responses, which varied extensively among the patients, public and medical staff.
Timing, delays and pathways to diagnosis of endometriosis: a scoping review protocol
Authors: Cromeens Martha Grace , Carey Erin T. , Robinson Whitney R. , Knafl Kathleen , Thoyre Suzanne 
Published: June 2021

IntroductionPathways to diagnosis for women with endometriosis are frequently characterised with delays. Internationally, women face significant barriers and times to diagnosis. The prolonged time without a diagnosis may result in treatment delay, with clinical implications of chronic pain and an unknown effect on fertility outcomes. As delays in diagnosis extend, those suffering from endometriosis incur more cost and frequently experience a reduction in quality of life. The scoping review described in this protocol will (1) map current international scientific peer-reviewed and grey literature investigating pathways, timing, and delay of diagnosis of endometriosis, (2) define common concepts used in the literature, and (3) identify gaps for future examination and intervention development.Methods and analysisThis protocol outlines a scoping review to investigate the current research focused on pathways, timing, and delays in endometriosis diagnosis. The scoping review uses the Joanna Briggs Institute Methodology. The researchers applied the Population, Concept, Context approach to form the research questions. A search string of key terms and Medical Subject Headings will be used to systematically search the PubMed, CINAHL, EMBASE, Web of Science, and Cochrane databases. We will also search ClinicalTrials.gov and grey literature sources. The original search was performed in July 2020, and it will be rerun prior to the manuscript submission. Finally, the reference lists of included works will be reviewed for additional studies. The search results will be screened and reviewed according to predetermined inclusion and exclusion criteria. Data will be extracted from the studies identified for final inclusion using a predetermined tool. The resulting data will be analysed to report the state of the science.Ethics and disseminationThe proposed scoping review does not require review or approval by an ethical board. The researchers will disseminate the study results via conference presentations and publication in a peer-reviewed journal.