bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the Parameters Governing Linkage-Based Rocking Chairs
Authors: Canfield Stephen L. , Beard James W. , Soper R. Randall 
Published: December 2020

Abstract
This paper will discuss several of the kinematic and dynamic issues in developing a linkage-based rocking chair or recliner. To create the gentle oscillating motion desired in such a chair, a number of mechanical systems could be used. The most common mechanisms historically have consisted of three types: a pendulum type (e.g., a porch swing), a traditional cam-based rocking chair and a linkage-based design in which the suspended coupler is free to swing with a single degree of freedom. A number of factors effect the desirability of the motion of these chairs including the range of linear displacement, range of angular displacement, peak accelerations and acceleration profile, period, ease of generating and maintaining the oscillatory motion, and stability. One of the primary factors is the period; a longer period in the net usually indicates slower, gentler motion in any isolated segment of the oscillation.
The intrinsic advantages of linkage-based rocking chairs have motivated progressive companies within the industry to choose glider rockers as a significant part of or signature product in their product lines. Based on the criteria desired in a rocking chair, an approach to the design of linkage-based rockers is being developed. While many analytical, graphical, and optimal synthesis techniques are available which consider all possible factors in linkage design, simpler, single parameter or reduced-parameter-set approaches to the development of candidate linkages are highly desirable. This paper will present an investigation of a reduced-parameter-set approach to the synthesis of linkage-type rockers. The investigation will proceed with a simple theoretical and numerical analysis of simple rocking chairs, i.e., swing and circular-cam-based rockers, and then establish a means to extend the reduced-parameter-set design approach to the more complicated four-bar rockers. The paper will conclude with a discussion of the synthesis procedure as applied to the creation of a prototype linkage-based rocker.
The Combined Influence of Helix Angle and Total Contact Ratio on the p-FEM Calculated Tooth Root Stress in Cylindrical Gears
Authors: Piazza Andrea , Uberti Maurizio 
Published: December 2020

Abstract
Many parametrical studies about the effect of the helix angle on the maximum tooth root stress on cylindrical gears were conducted by means of a p-FEM (polynomial Finite Element Method) analysis, using models that comprehend all the contacting teeth and the adjacent ones. The studies were conducted in a way that the helix angle was varied from 0 to 35 degrees, keeping the transverse section constant (i.e. twisting the gears). Many non-HCR existing spur and helical gearsets, with different transverse contact ratio εα, transmission ratio, pressure angle, correction factor, and facewidth to module ratio were examined. Neither profile modification, nor crowning were considered. For each gearset the maximum p-FEM-calculated tooth root stress in both pinion and gear drops considerably when the total contact ratio εγ reaches the value of 2, with a minimum noticed around εγ = 2.1 ÷ 2.4; then the stress rises monotonically except for a non-remarkable drop when εγ reaches the value of 3. The p-FEM results were also compared with those based on ISO 6336-3 method B and AGMA 2001, showing noticeable differences.
Determination of the Tooth Surface Friction Coefficient of a Pair of Mating Gears Based on the Distribution Along the Tooth Profile Precisely Measured With the Gravity Pendulum Method
Authors: Hori Kohei , Hayashi Iwao , Iwatsuki Nobuyuki 
Published: December 2020

Abstract
A new gravity pendulum method has been proposed in order to precisely measure the tooth surface friction coefficient of a pair of mating gears excluding the bearing loss. In this method, one of the mating gears, which is fixed on a gravity pendulum, is put on the other gear, which is fixed on the ground, and is freely oscillated. The center-to-center distance between the mating gears is kept constant with a flexure hinge mechanism in order to accurately reproduce the relative motion, including rolling and sliding, between the tooth surfaces of practical rotating gears. This method has a great advantage, in that the tooth surface friction co-efficient can be measured in a very small region of the tooth profile, because the initial oscillation amplitude can be set approximately one arc-degree. The distribution of the friction coefficients along the tooth surface has been precisely measured for the exact one pair-, inexact one pair-, and two pair-tooth engagements of an internal gear pair and an external gear pair. Also, the mean values of the distributed tooth surface friction coefficients are calculated by taking the specific sliding between the tooth surfaces into account, and are compared with each other.
Surface Temperature Calculation and its Application for the Surface Fatigue Strength Evaluation of Rollers
Authors: Deng Gang , Nakanishi Tsutomu , Ikeda Hironori 
Published: December 2020

Abstract
Surface temperature is resulted by not only the load and dimension at the contact point but also the sliding velocity, rolling velocity, surface roughness, lubrication condition and etc. So, the surface fatigue strength of such as roller and gear may be evaluated more exactly and simply by use of the surface temperature or an index including the surface temperature than the Hertzian stress. In this research, the surface temperatures of rollers in different rolling and sliding conditions were measured with a thermocouple. The effects of the load P, mean velocity Vm and sliding velocity Vs on the surface temperature are clarified. An experimental formula, which expresses a linear relationship between the surface temperature and the P0.86Vs1.31Vm−0.83 value, is presented to calculate the surface temperature. This formula is also confirmed available for the gear tooth surface temperature calculation by comparison of calculated temperature and the measured temperature on the gear tooth surface. The relationship between the surface temperature and the number of load cycles of rollers are investigated, the necessity and rationality of the surface fatigue strength evaluation considering the surface temperature are discussed.
Consideration of Moving Tooth Load in Gear Crack Propagation Predictions
Authors: Lewicki David G. , Spievak Lisa E. , Wawrzynek Paul A. , Ingraffea Anthony R. , Handschuh Robert F. 
Published: December 2020

Abstract
Robust gear designs consider not only crack initiation, but crack propagation trajectories for a fail-safe design. In actual gear operation, the magnitude as well as the position of the force changes as the gear rotates through the mesh. A study to determine the effect of moving gear tooth load on crack propagation predictions was performed. Two-dimensional analysis of an involute spur gear and three-dimensional analysis of a spiral-bevel pinion gear using the finite element method and boundary element method were studied and compared to experiments. A modified theory for predicting gear crack propagation paths based on the criteria of Erdogan and Sih was investigated. Crack simulation based on calculated stress intensity factors and mixed mode crack angle prediction techniques using a simple static analysis in which the tooth load was located at the highest point of single tooth contact was validated. For three-dimensional analysis, however, the analysis was valid only as long as the crack did not approach the contact region on the tooth.
A Novel Approach of Obtaining Localized Tooth Contact for Spiroid Gear Drives
Authors: Su Daizhong , Song Yongle , Gentle Richard C. 
Published: December 2020

Abstract
A novel approach to obtaining localized bearing contact of spiroid gear drives has been developed. The localized contact is achieved by modifying the pinion tooth surface. With this approach, only the pinion cutter’s geometrical angles and mounting position need to be adjusted, and, hence, it is simpler and more economical than other methods. In this paper the following are presented: overview of the approach, equations for modified spiroid gear tooth geometry, and computer simulation results. The results confirm that the proposed modification of the tooth geometry pennits localized bearing contact.
Design of a Self-Actuating, Traction Drive Speed Reducer
Authors: Flugrad Donald R. , Qamhiyah Abir Z. 
Published: December 2020

Abstract
Traction drive speed reducers offer certain advantages over geared speed reducers. In particular, they generally run quieter than geared units, and they provide an opportunity for higher efficiency by eliminating sliding motion between contacting elements.
In order to generate a sufficiently high output torque, some means must be provided to create a normal force between the rolling elements. This normal force, along with the friction coefficient, enables the device to transmit torque from one rolling member to the next. The speed reducer proposed here is designed so that the configuration of the rolling elements creates the needed normal force in response to the torque exerted back on the system by the downstream loading. Thus the device is self-actuating.
Since the normal force is only present when needed, the rolling elements of the device can readily be disengaged. This eliminates the need for a separate clutch in the drive system. This feature can be exploited to design a transmission with several distinct speed ratios which can be engaged and disengaged in response to changing speed requirements.
Modeling the Nonlinear Vibration of a Spur Gear Pair
Authors: Parker R. G. , Vijayakar S. M. , Imajou T. 
Published: December 2020

Abstract
The dynamic response of a spur gear pair is investigated using a finite element/contact mechanics model that offers significant advantages for dynamic gear analyses. The gear pair is analyzed across a wide range of operating speeds and torques. Comparisons are made to other researchers’ published experiments that reveal complex nonlinear phenomena. The nonlinearity source is contact loss of the meshing teeth, which, in contrast to the prevailing understanding, occurs even for large torques despite use of high-precision gears. A primary feature of the modeling is that dynamic mesh forces are calculated using detailed contact analysis at each time step as the gears roll through mesh; there is no need to externally specify the excitation in the form of time-varying mesh stiffness, static transmission error input, or the like. A semi-analytical model near the tooth surface is matched to a finite element solution away from the tooth surface, and the computational efficiency that results permits dynamic analysis. Two single degree of freedom models are discussed briefly. While one gives encouragingly good results, the second, which appears to have better mesh stiffness modeling, gives poor comparisons with experiments. The results indicate the sensitivity of such models to changing mesh stiffness representations.
Dynamics of a Transmission System Having a Cracked Gear Tooth
Authors: Berri Sidi M. , Klosner J. M. 
Published: December 2020

Abstract
The present study is a combined experimental/analytical investigation of the effect of a cracked pinion tooth on the vibrational characteristics of a power transmission system. It is part of an ongoing effort to develop strategies for locating and quantifying local defects by properly processing and interpreting the output signals. Presented, is a system of nonlinear equations representing the analytical model of an experimental test rig. The model includes the effect of crack size on the time-varying gear mesh stiffness, and the equations are solved by using a Newmark-Beta numerical integration scheme. The numerically and experimentally obtained signals, processed by using the wavelet transform, show excellent agreement over a range of crack sizes and running speeds, thus suggesting that mathematical simulation can provide a useful tool for quantifying cracks.
Introducing Fuzzy Logic Analysis in the Life Cycle of Mechanical Systems
Authors: Drakatos P. A. , Kallaras M. , Karakassis K. 
Published: December 2020

Abstract
During an operation a mechanical system cost is a function of the time operation. Until now, we have taken into account the variation of economical factors as a function of time. The present work tries to import fuzzy logic in order to determine a variable model of economical factors as a reference to stillness, lubrication, repair of the mechanical systems and the variation of the operation tensions as for time. Which important levels are the mechanical systems so time operation affects the equivalent cost. The fuzzy logic model which was established, have data which was measured in the past and these data make a model with polynomial method, which doesn’t gives trustworthily results. The use of computer software is important because this method is variable as a function of cost and time.
Implementation of C-reactive protein point of care testing to improve antibiotic targeting in respiratory illness in Vietnamese primary care (ICAT): a study protocol for a cluster randomised controlled trial
Authors: Thi Thuy Do Nga , Greer Rachel Claire , Lubell Yoel , Dittrich Sabine , Vandendorpe Maida , Nguyen Van Anh , Ngoc Thach Pham , Thi Dieu Ngan Ta , Van Kinh Nguyen , Hung Thai Cao , Dung Le Thi Kim , Nguyen Thi Cam Tu , Nguyen Thanh Ha , Nadjm Behzad , van Doorn H Rogier , Lewycka Sonia 
Published: December 2020

IntroductionC-reactive protein (CRP), a biomarker of infection, has been used widely in high-income settings to guide antibiotic treatment in patients presenting with respiratory illnesses in primary care. Recent trials in low- and middle-income countries showed that CRP testing could safely reduce antibiotic use in patients with non-severe acute respiratory infections (ARIs) and fever in primary care. The studies, however, were conducted in a research-oriented context, with research staff closely monitoring healthcare behaviour thus potentially influencing healthcare workers’ prescribing practices. For policy-makers to consider wide-scale roll-out, a pragmatic implementation study of the impact of CRP point of care (POC) testing in routine care is needed.Methods and analysisA pragmatic, cluster-randomised controlled trial, with two study arms, consisting of 24 commune health centres (CHC) in the intervention arm (provision of CRP tests with additional healthcare worker guidance) and 24 facilities acting as controls (routine care). Comparison between the treatment arms will be through logistic regression, with the treatment assignment as a fixed effect, and the CHC as a random effect. With 48 clusters, an average of 10 consultations per facility per week will result in approximately 520 over 1 year, and 24 960 in total (12 480 per arm). We will be able to detect a reduction of 12% to 23% or more in immediate antibiotic prescription as a result of the CRP POC intervention. The primary endpoint is the proportion of patient consultations for ARI resulting in immediate antibiotic prescription. Secondary endpoints include the proportion of all patients receiving an antibiotic prescription regardless of ARI diagnosis, frequency of re-consultation, subsequent antibiotic use when antibiotics are not prescribed, referral and hospitalisation.Ethics and disseminationThe study protocol was approved by the Oxford University Tropical Research Ethics Committee (OxTREC, Reference: 53–18), and the ethical committee of the National Hospital for Tropical Diseases in Vietnam (Reference:07/HDDD-NDTW/2019). Results from this study will be disseminated via meetings with stakeholders, conferences and publications in peer-reviewed journals. Authorship and reporting of this work will follow international guidelines.Trial registration detailsNCT03855215; Pre-results.
Early prediction of in-hospital mortality in acute pancreatitis: a retrospective observational cohort study based on a large multicentre critical care database
Authors: Li Caifeng , Ren Qian , Wang Zhiqiang , Wang Guolin 
Published: December 2020

ObjectiveTo develop and validate a prediction model for predicting in-hospital mortality in patients with acute pancreatitis (AP).DesignA retrospective observational cohort study based on a large multicentre critical care database.SettingAll subject data were collected from the eICU Collaborative Research Database (eICU-CRD), which covers 200 859 intensive care unit admissions of 139 367 patients in 208 US hospitals between 2014 and 2015.ParticipantsA total of 746 patients with AP were drawn from eICU-CRD. Due to loss to follow-up (four patients) or incomplete data (364 patients), 378 patients were enrolled in the primary cohort to establish a nomogram model and to conduct internal validation.Primary and secondary outcome measuresThe outcome of the prediction model was in-hospital mortality. All risk factors found significant in the univariate analysis were considered for multivariate analysis to adjust for confounding factors. Then a nomogram model was established. The performance of the nomogram model was evaluated by the concordance index (C-index) and the calibration plot. The nomogram model was internally validated using the bootstrap resampling method. The predictive accuracy of the nomogram model was compared with that of Acute Physiology, Age, and Chronic Health Evaluation (APACHE) IV. Decision curve analysis (DCA) was performed to evaluate and compare the potential net benefit using of different predictive models.ResultsThe overall in-hospital mortality rate is 4.447%. Age, BUN (blood urea nitrogen) and lactate (ABL) were the independent risk factors determined by multivariate analysis. The C-index of nomogram model ABL (0.896 (95% CI 0.825 to 0.967)) was similar to that of APACHE IV (p=0.086), showing a comparable discriminating power. Calibration plot demonstrated good agreement between the predicted and the actual in-hospital mortality. DCA showed that the nomogram model ABL was clinically useful.ConclusionsNomogram model ABL, which used readily available data, exhibited high predictive value for predicting in-hospital mortality in AP.
Combination of InnoSEAL plus TR band compared with TR band alone for radial artery outcomes in patients undergoing transradial coronary intervention (InnoSEAL-II): an open-label randomised controlled trial (protocol)
Authors: Aijaz Saba , Sheikh Sana , Pathan Asad 
Published: December 2020

IntroductionAbout 2%–30% of cardiac catheterisation procedures get complicated by radial artery occlusion (RAO). Ensuring patent haemostasis appears to be an important factor in reducing RAO. Currently employed method is a radial compression device (RCD) such as transradial band (TRB) that take hours to achieve haemostasis and cause discomfort to the patients. Haemostatic pads offer an alternative to RCD with reduced time to achieve haemostasis. Our trial aims to determine the non-inferiority of the catecholamine chitosan-based pad (InnoSEAL haemostatic pad) used in conjunction with TRB (InnoSEAL +TRB) when compared with the TRB alone in reducing composite adverse access site outcomes.Methods and analysisIt will be an open-label, parallel, randomised controlled trial on 714 adult patients (325 in each arm) undergoing coronary procedure using transradial approach at a cardiac health facility over 7 months duration. InnoSEAL patch along with TRB will be used to control bleeding in intervention arm and TRB alone in control arm, which is the standard practice. Study primary outcomes include RAO and haematoma; secondary outcomes are compression time, patient discomfort, time to discharge and ease of use of the intervention technique by the healthcare staff. χ2 test will be used to compare the categorical outcomes between two arms and student’s t-test for continuous outcomes. A p value of <0.05 will be considered significant.Ethics and disseminationEthical approval for the study has been obtained from the Institutional Review Board of Tabba Heart Institute number IORG0007863. Findings will be disseminated through seminars and scientific publications.Trial registration numberNCT04380883; Pre-results.
Temporal trends in incidence of atrial fibrillation in primary care records: a population-based cohort study
Authors: Mendonça Sílvia C , Saunders Catherine L , Lund Jenny , Mant Jonathan , Edwards Duncan 
Published: December 2020

ObjectivesAtrial fibrillation (AF) is a heart condition associated with a fivefold increased risk of stroke. The condition can be detected in primary care and treatment can greatly reduce the risk of stroke. In recent years, a number of policy initiatives have tried to improve diagnosis and treatment of AF, including local National Health Service schemes and the Quality and Outcomes Framework. We aimed to examine trends in the incidence of recorded AF in primary care records from English practices between 2004 and 2018.DesignLongitudinal cohort study.SettingEnglish primary care electronic health records linked to Index of Multiple Deprivation data.ParticipantsCohort of 3.5 million patients over 40 years old registered in general practices in England, contributing 22 million person-years of observation between 2004 and 2018.Primary and secondary outcome measuresIncident AF was identified through newly recorded AF codes in the patients’ records. Yearly incidence rates were stratified by gender, age group and a measure of deprivation.ResultsIncidence rates were stable before 2010 and then rose and peaked in 2015 at 5.07 (95% CI 4.94 to 5.20) cases per 1000 person-years. Incidence was higher in males (4.95 (95% CI 4.91 to 4.99) cases per 1000 person-years vs 4.12 (95% CI 4.08 to 4.16) in females) and rises markedly with age (0.58 (95% CI 0.56 to 0.59) cases per 1000 person-years in 40–54 years old vs 21.7 (95% CI 21.4 to 22.0) cases in over 85s). The increase in incidence over time was observed mainly in people over the age of 75, particularly men. There was no evidence that temporal trends in incidence were associated with deprivation.ConclusionsChanges in clinical practice and policy initiatives since 2004 have been associated with increased rates of diagnosis of AF up until 2015, but rates declined from 2015 to 2018.