bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deflection and Stresses in Beams Subjected to Bending and Creep
Authors: Pao Yoh-Han , Marin Joseph 
Published: April 2021

Abstract
This paper presents theories for the determination of deflections and stresses in beams subjected to bending and creep. The theories are based on a creep-stress-time relation in simple tension which gives an accurate fit of most test data. The theory takes into account the variation in stress distribution in bending with time. For this purpose a time-hardening theory is used to express the stress variation or stress relaxation of each fiber in bending. A comparison between actual creep deflections for Plexiglas specimens subjected to pure bending and values predicted by the proposed theory shows good agreement between experimental and theoretical results. The creep behavior for other materials in tension indicates that this method could be used for predicting bending creep deflections for these materials. The application of the theory to the determination of deflections in various kinds of beams is also explained.
A Simple Method of Determining Plastic Stresses and Strains in Rotating Disks With Nonuniform Metal Properties
Authors: Wu M. H. Lee 
Published: April 2021

Abstract
This paper presents a simple method of solving plastic deformation of a rotating disk having nonuniform metal properties. A stress-strain surface, which is formed by stress-strain curves obtained from the tensile specimens cut at different radii of the disk in the tangential direction, is introduced. The distributions of plastic stresses and strains can be obtained by a simple multiplication with the use of a short table given in the paper and a stress-strain curve along the radius of the disk determined from the stress-strain surface. The rotating-speed parameter is simplified to a simple algebraic function of maximum octahedral shear strain of the disk, and a parameter determined directly from the stress-strain curve along the radius of the disk. A chart calculated from such relations is given. The relation between rotating speed and maximum strain determined from the chart are compared with the experimental data of disk test; results agree well.
Stress Singularities Resulting From Various Boundary Conditions in Angular Corners of Plates in Extension
Authors: Williams M. L. 
Published: April 2021

Abstract
As an analog to the bending case published in an earlier paper, the stress singularities in plates subjected to extension in their plane are discussed. Three sets of boundary conditions on the radial edges are investigated: free-free, clamped-clamped, and clamped-free. Providing the vertex angle is less than 180 degrees, it is found that unbounded stresses occur at the vertex only in the case of the mixed boundary condition with the strength of the singularity being somewhat stronger than for the similar bending case. For vertex angles between 180 and 360 degrees, all the cases considered may have stress singularities.
In amplification of some work of Southwell, it is shown that there are certain analogies between the characteristic equations governing the stresses in extension and bending, respectively, if ν, Poisson’s ratio, is replaced by −ν. Finally, the free-free extensional plate behaves locally at the origin exactly the same as a clamped-clamped plate in bending, independent of Poisson’s ratio.
In conclusion, it is noted that the free-free case analysis may be applied to stress concentrations in V-shaped notches.
The Stresses in a Flat Curved Bar Due to Concentrated Radial Loads
Authors: Nelson C. W. , Ancker C. J. , Wu Ning-Gau 
Published: April 2021

Abstract
This paper presents a Fourier integral solution for the plane-stress problem of a curved bar bounded by two concentric circles and loaded by any combination of radial loads on the circular boundaries. It is an extension of an earlier investigation (1) which dealt with only the particular case of a curved bar in equilibrium under the action of two equal and opposite radial forces, one on each boundary. Numerical results are given for one of two basic cases from which the stresses for any combination of concentrated radial loads may be obtained by superposition. An example is included to show how superposition may be used to obtain the stresses for a loading condition which may occur frequently in practical machine-design problems. It is believed that the procedures developed in this paper will be useful in the solution of other elasticity problems by the Fourier integral method.
Resolving Pitching Airfoil Transonic Aerodynamics by Computational Fluid Dynamics Data Modeling1
Authors: Kaul Upender K. 
Published: April 2021

Abstract
A detailed numerical study of harmonically pitching airfoils of NACA00 series is presented here. Based on the analysis of the computational fluid dynamics (CFD) results, a hypothesis is made that a simple data model can capture the dynamics of the airfoils in pitch. The data model is based on the cl−α (lift coefficient–angle of attack) hysteresis loops that retain generic geometrical characteristics for a wide range of reduced frequency, k, encountered in flutter in transonic flows for all the NACA00 airfoils considered. The model was trained on a subset of the considered NACA00 airfoils and then tested on the remaining NACA00 set, for a subset of the reduced frequencies. The model predictions of the cl−α hysteresis loops for the test set are shown to be in excellent agreement with the CFD results for the range of k typical of transonic flutter. The data model offers a paradigm shift in the prediction of transonic flow dynamics of pitching airfoils and will guide the development of a new transfer function that will be incorporated in a new aeroelastic framework leading to an appropriate transonic flutter model for use in the development of future aircraft.
A Comparison of the Turbine Tower Damping Effects of a Series of Back Twisted Active Pitch-to-Stall Blades for a Spar and a Semi-Submersible FOWT
Authors: Ward Dawn , Collu Maurizio , Sumner Joy 
Published: April 2021

Abstract
Floating offshore wind turbines are subjected to higher tower fatigue loads than their fixed-to-seabed counterparts, which could lead to reductions in turbine life. The worst increases are generally seen in the tower axial fatigue, associated with the tower fore-aft bending moment. For a spar type platform, this has been shown to increase by up to 2.5 times and for a semi-submersible platform, by up to 1.8 times. Reducing these loads would be beneficial, as the alternative of strengthening the towers leads to increase in cost. Here, two offshore floating wind turbine systems, of the spar type, are analyzed and selected responses and tower fatigue are compared: one incorporates a variable-speed, variable-pitch-to-stall blade control system and a back twisted blade, and the other a conventional pitch-to-feather control. The results are then compared with those obtained in an earlier study, where the same turbine configurations were coupled to a semi-submersible platform. A weighted wind frequency analysis at three mean turbulent wind speeds of 8, 13, and 18 m/s highlights that the impact of the back twist angle magnitude and initiation point on tower axial fatigue life extension was the same for both platform types. Compared with their respective feather base models, an increase in the tower axial fatigue life of 18.8% was seen with a spar platform and 10.2% with a semi-submersible platform, when a back twist angle to the tip of −6 deg was imposed along with the variable-speed, variable-pitch-to-stall control.
WraptMor: Confirmation of an Approach to Estimate Ligament Fiber Length and Reactions With Knee-Specific Morphology
Authors: Zaylor William , Halloran Jason P. 
Published: April 2021

Abstract
Knee ligament length can be used to infer ligament recruitment during functional activities and subject-specific morphology affects the interplay between ligament recruitment and joint motion. This study presents an approach that estimated ligament fiber insertion-to-insertion lengths with wrapping around subject-specific osseous morphology (WraptMor). This represents an advancement over previous work that utilized surrogate geometry to approximate ligament interaction with bone surfaces. Additionally, the reactions each ligament imparted onto bones were calculated by assigning a force–length relationship (kinetic WraptMor model), which assumed that the insertion-to-insertion lengths were independent of the assigned properties. Confirmation of the approach included comparing WraptMor predicted insertion-to-insertion length and reactions with an equivalent displacement-controlled explicit finite element model. Both models evaluated 10 ligament bundles at 16 different joint positions, which were repeated for five different ligament prestrain values for a total of 80 simulations per bundle. The WraptMor and kinetic WraptMor models yielded length and reaction predictions that were similar to the equivalent finite element model. With a few exceptions, predicted ligament lengths and reactions agreed to within 0.1 mm and 2.0 N, respectively, across all tested joint positions and prestrain values. The primary source of discrepancy between the models appeared to be caused by artifacts in the finite element model. The result is a relatively efficient approach to estimate ligament lengths and reactions that include wrapping around knee-specific bone surfaces.
Kinematic Analysis and Optimal Design of a Novel Schönflies-Motion Parallel Manipulator With Rotational Pitch Motion for Assembly Operations
Authors: Yang Xiansheng , Zhao Zhilong , Xiong Hao , Li Qinchuan , Lou Yunjiang 
Published: April 2021

Abstract
This paper presents a novel Schönflies-motion Parallel Manipulator with RotationalPitch motion (SPM-RP) based on a single-platform fully parallel mechanism. An analysis of the position, workspace, velocity, and singularity of the SPM-RP is carried out in detail, and a dimensionless Jacobian is proposed to evaluate the manipulability of the SPM-RP. The analysis shows that the SPM-RP is with position-decoupled kinematics, a large singularity-free workspace, and excellent manipulability. The SPM-RP is actuated by four parallel prismatic actuators, enabling the manipulator to provide the identical kinematic performance at all generic cross sections perpendicular to the prismatic joint axes within its workspace. This paper thus proposes a reduced design optimization formulation, where the traditional optimization over the entire workspace is reduced to the optimization on a representative workspace cross section of the SPM-RP. According to this approach, the design optimization of the SPM-RP is carried out by maximizing its manipulability over the total orientation workspace, which is crucial for precision assembly. Based on the achieved optimal design, an SPM-RP prototype is developed. The mobility, orientation capability, total orientation workspace, and repeatability of the optimal design are tested and verified by the developed SPM-RP prototype. Experiments show that the SPM-RP can achieve a large total orientation workspace with excellent precision performance.
A Reformulation of Degree of Disequilibrium Analysis for Automatic Selection of Kinetic Constraints in the Rate-Controlled Constrained-Equilibrium Method
Authors: Hadi Fatemeh , Roy Shrabanti , Askari Omid , Beretta Gian Paolo 
Published: April 2021

Abstract
The rate-controlled constrained equilibrium (RCCE) is a model reduction scheme for chemical kinetics. It describes the evolution of a complex chemical system with acceptable accuracy with a number of rate controlling constraints on the associated constrained-equilibrium states of the system, much lower than the number of species in the underlying detailed kinetic model (DKM). Successful approximation of the constrained-equilibrium states requires accurate identification of the constraints. One promising procedure is the fully automatable Approximate Singular Value Decomposition of the Actual Degrees of Disequilibrium (ASVDADD) method that is capable of identifying the best constraints for a given range of thermodynamic conditions and a required level of approximation. ASVDADD is based on simple algebraic analysis of the results of the underlying DKM simulation and is focused on the behavior of the degrees of disequilibrium (DoD) of the individual chemical reactions. In this paper, we introduce an alternative ASVDADD algorithm. Unlike the original ASVDADD algorithm that require the direct computation of the DKM-derived DoDs and the identification of the set of linearly independent reactions, in the alternative algorithm, the components of the overall degree of disequilibrium vector can be computed directly by casting the DKM as an RCCE simulation considering a set of linearly independent constraints equaling the number of chemical species in size. The effectiveness and robustness of the derived constraints from the alternative procedure is examined in hydrogen/oxygen and methane/oxygen ignition delay simulations and the results are compared with those obtained from DKM.
Origin and age of the Shenshan tectonic mélange in the Jiangshan-Shaoxing-Pingxiang Fault and late Early Paleozoic juxtaposition of the Yangtze Block and the West Cathaysia terrane, South China
Authors: Wang Lijun , Zhang Kexin , Lin Shoufa , He Weihong , Yin Leiming 
Published: April 2021

AbstractWhen and how the Yangtze Block (Yangtze) and the West Cathaysia terrane (West Cathaysia) in South China were amalgamated are critical to a better understanding of the Neoproterozoic to early Paleozoic tectonic evolution of South China and remain highly debatable. A key to this debate is the tectonic significance of the Jiangshan-Shaoxing-Pingxiang (JSP) Fault, the boundary between Yangtze and West Cathaysia. The Shenshan mélange along the JSP Fault has the typical block-in-matrix structure and is composed of numerous shear zone-bounded slivers/lenses of rocks of different types and ages that formed in different tectonic environments, including middle to late Tonian volcanic and volcanogenic sedimentary rocks (turbidite) of arc/back-arc affinity, a series of middle Tonian ultramafic to mafic plutonic rocks of oceanic island basalt affinity, a carbonaceous shale that was deposited in a deep marine environment, and a red mudstone. U-Pb zircon ages and acritarch assemblages (Leiosphaeridia-Brocholaminaria association) found in the turbidite confirm its Tonian age, and fossils from the carbonaceous shale (Asteridium-Comasphaeridium and Skiagia-Celtiberium-Leiofusa) constrains its age to the Early to Middle Cambrian. Field relationships and available age data leave no doubt that the ultramafic-mafic rocks are exotic blocks (rather than intrusions) in the younger metasedimentary rocks. We conclude that the Shenshan mélange is not an ophiolitic mélange, but rather a tectonic mélange that formed as a result of movement along the JSP Fault in the early Paleozoic. We suggest that Yangtze and West Cathaysia were two separate microcontinents, were accreted to two different parts of the northern margin of Gondwana in the early Early Paleozoic, and juxtaposed in the late Early Paleozoic through strike-slip movement along the JSP Fault. We further suggest that the ca. 820 Ma collision in the Jiangnan Orogen took place between Yangtze and a (micro)continent that is now partly preserved as the Huaiyu terrane and was not related to West Cathaysia. We compare our model for South China with the accretion of terranes in the North American Cordillera and propose a similar model for the relationship between the Avalon and Meguma terranes in the Canadian Appalachians, i.e., the two terranes were accreted to two different parts of the Laurentian margin and were later juxtaposed through margin-parallel strike slip faulting.
Retinal vascular bed area on ultra-wide field fluorescein angiography indicates the severity of diabetic retinopathy
Authors: Fan Wenying , Uji Akihito , Nittala Muneeswar , Wykoff Charles Clifton , Brown David , Fleming Alan , Robertson Gavin , van Hemert Jano , Sadda SriniVas , Ip Michael S 
Published: April 2021

AimsTo quantify retinal vascular bed area (RVBA) in square millimetres on stereographically projected ultra-wide field (UWF) fluorescein angiography (FA) in eyes with diabetic retinopathy (DR).MethodsA prospective, observational study. Baseline Optos 200Tx UWF FA images of 80 eyes with DR from the DAVE (NCT01552408) and RECOVERY (NCT02863354) studies were stereographically projected at the Doheny Image Reading Center to adjust for peripheral distortion. The early-phase FA frame was used to extract the retinal vasculature as a mask for calculating RVBA. The pixels of the retinal vasculature were automatically computed in square millimetres using manufacturer-provided software.ResultsEighteen of 80 diabetic eyes were excluded because image quality and contrast were insufficient for automatic extraction of the retinal vasculature from the background fluorescence. The remaining 62 eyes were included in the final analysis. In comparison with age-matched and sex-matched normal controls, eyes with DR had a higher global RVBA for the entire retina (p<0.001), and RVBA correlated with DR severity (p<0.001), with a higher RVBA in eyes with proliferative DR (66.1±16.2 mm2) than in those with non-proliferative DR (56.2±16.6 mm2) or in normal controls (37.2±9.9 mm2). This tendency was also present in the posterior retina and mid-periphery but absent in the far-periphery. RVBA did not correlate with retinal ischaemia (p>0.05).ConclusionsEyes with DR harboured a larger global RVBA for the entire retina than normal controls, and RVBA appeared to indicate DR severity. However, this biomarker was not observed to be a good indicator of retinal ischaemia.
Association of foveal avascular zone area withstructural and functional progression in glaucoma patients
Authors: Li Fei , Lin Fengbin , Gao Kai , Cheng Weijing , Song Yunhe , Liu Yuhong , Wang Yu Meng , Lam Alexander , Tham Clement C , Cheung Carol , Zhang Xiulan , Zangwill Linda M. 
Published: April 2021

BackgroundTo investigate whether quantitative optical coherence tomography angiography (OCTA) metrics of the superficial/deep macular retina and optic disc are associated with glaucoma progression risk.MethodsA total of 238 eyes from 119 patients with open angle glaucoma or ocular hypertension, and no history of systemic hypertension or diabetes mellitus were included. All participants underwent OCTA imaging with a swept-source OCT (DRI-OCT 1, Topcon, Japan). OCTA metrics of superficial capillary plexus (SCP) and deep capillary plexus (DCP) in the macular region, and radial peripapillary capillary network of the optic disc were measured by a customised MATLAB program to obtain foveal avascular zone (FAZ) area, FAZ circularity and capillary density of SCP/DCP, and capillary density of the peripapillary region. Relationships between baseline OCTA metrics, visual field (VF) metrics, intraocular pressure fluctuation and risk of glaucoma progression were analysed with the Cox proportional hazards model. A frailty model was used to adjust for intereye correlation.ResultsDuring a mean follow-up duration of 29.39 months (range 12–56 months), 50, 48 and 16 eyes were determined to have retinal nerve fibre layer (RNFL), ganglion cell-inner plexiform layer (GC-IPL) and VF progression respectively. FAZ area per SD increase at baseline were significantly associated with both RNFL thinning (HR 1.73 95% CI 1.04 to 2.90); p=0.036) and GC-IPL thinning (HR 2.62, 95% CI 1.59 to 4.31; p<0.001), after adjusting for age, axial length and other potential confounding factors. VF progression was associated with age (HR 1.05, 95% CI 1.02 to 1.08; p<0.001) and mean deviation value (HR 0.91, 95% CI 0.84 to 0.98; p=0.010), but not with any OCTA metrics.ConclusionEnlarged FAZ area measured by OCTA was associated with a higher risk of RNFL and GC-IPL thinning associated with glaucoma, but not with functional deterioration in glaucoma.
From hospitalisation to primary care: integrative model of clinical pharmacy with patients implanted with a PICC line—research protocol for a prospective before–after study
Authors: Pouget Alix Marie , Civade Elodie , Cestac Philippe , Rouzaud-Laborde Charlotte 
Published: April 2021

IntroductionClinical pharmacy improves patient safety and secures drug management using information, education and good clinical practices. However, medical device management is still unexplored, and proof of effectiveness is needed. A PICC line (peripherally inserted central catheter) is a medical device for infusion. It accesses the central venous system after being implanted in a peripheral vein. However, complications after implantation often interfere with smooth execution of the treatment. We hypothesise that clinical pharmacy for medical devices could be as effective as clinical pharmacy for medications. The main objective is to assess the effectiveness of clinical pharmacy activities on the complication rate after PICC line implantation.Methods and analysisThis is a before–after prospective study. The study will begin with an observational period without clinical pharmacy activities, followed by an interventional period where pharmacists will intervene on drug and medical device management and provide personalised follow-up and advice. Sixty-nine adult patients will be recruited in each 6-month period from all traditional care units. The main inclusion criteria will be the implantation of a PICC line. The primary outcome is the decrease in the number of complications per patient and per month. Secondary outcomes are the consultation and hospital readmission rates, the acceptance rate of pharmaceutical interventions, the patients’ quality of life, the direct hospital induced or avoided costs and the participants’ satisfaction. Data will be collected using case report forms during hospitalisation and telephone follow-up after discharge. The analysis will compare these criteria during the two periods.Ethics and disseminationThe study has received the approval of our Ethics Committee (Clermont-Ferrand Southeast VI, France, number AU1586). Results will be made available to the patients or their caregivers, the sponsor and other researchers when asked, as described in the consent form.Trial registration numberNCT04359056.
Outcomes of out-of-hospital cardiac arrest in Beijing: a 5-year cross-sectional study
Authors: Shao Fei , Li Haibin , Ma Shengkui , Li Dou , Li Chunsheng 
Published: April 2021

ObjectiveThe purpose of this study was to assess the trends in outcomes of out-of-hospital cardiac arrest (OHCA) in Beijing over 5 years.DesignCross-sectional study.MethodsAdult patients with OHCA of all aetiologies who were treated by the Beijing emergency medical service (EMS) between January 2013 and December 2017 were analysed. Data were collected using the Utstein Style. Cases were followed up for 1 year. Descriptive statistics were used to characterise the sample and logistic regression was performed.ResultsOverall, 5016 patients with OHCA underwent attempted resuscitation by the EMS in urban areas of Beijing during the study period. Survival to hospital discharge was 1.2% in 2013 and 1.6% in 2017 (adjusted rate ratio=1.0, p for trend=0.60). Survival to admission and neurological outcome at discharge did not significantly improve from 2013 to 2017. Patient characteristics and the aetiology and location of cardiac arrest were consistent, but there was a decrease in the initial shockable rhythm (from 6.5% to 5.6%) over the 5 years. The rate of bystander cardiopulmonary resuscitation (CPR) increased steadily over the years (from 10.4% to 19.4%).ConclusionSurvival after OHCA in urban areas of Beijing did not improve significantly over 5 years, with long-term survival being unchanged, although the rate of bystander CPR increased steadily, which enhanced the outcomes of patients who underwent bystander CPR.