bluuebunny/crossref_metadata_2025_split huggingface dataset:
Object Oriented Dexterity Analysis and Design Application for Spatial Robot Hands
Authors: Lu L. , Cai C. , Soni A. H. 
Published: April 2021

Abstract
For an arbitrarily shaped object manipulated by a robot hand, this paper presents a procedure for analyzing the position and rotation ranges of the object, and a procedure for designing the kinematic parameters of a hand to meet given requirements on the motion ranges. Rotation dexterity index, dexterity charts, and a dexterity scalar characterizing both position range and rotation range are introduced for the performance evaluation of a robot hand. Least-square-error iteration and steps are detailed for the kinematic parameter determination of a robot hand.
Computer-Oriented Dynamic Analysis Techniques in Vehicle System
Authors: Shin S. H. , Kim J. Y. , Yoo W. S. 
Published: April 2021

Abstract
Several dynamic analysis techniques are compared with a planar vehicle model. Cartesian formulation, the superelement technique, velocity transformation, and the recursive formula are compared. A recursive formula with multiple trees is derived and its simulation algorithm is also developed. The relation between the derived recursive formula and velocity transformation is investigated. When those techniques are applied to a planar vehicle with two independent suspensions, the efficiency of those methods can be evaluated. The efficiency of the derived recursive formula was higher than those of other methods.
A Low-Cost Real-Time Man-in-the-Loop Simulation for Multibody Systems
Authors: Chang J. L. , Kim S. S. 
Published: April 2021

Abstract
This paper presents a general approach for achieving real-time man-in-the-loop simulation for multibody dynamic systems. Emerging real-time dynamics simulation technologies are exploited to develop a low-cost network based simulator as an interactive design workstation with a human operator in the control loop. An efficient recursive dynamic formulation is used to create multibody dynamics models. A parallel processing algorithm is developed based on the recursive dynamics formulation and implemented on a multiprocessor computer to achieve real-time simulation. As a real-time integration algorithm, third-order Adams-Bashforth method is used. The integration stepsize is estimated from the eigenvalue analysis of the equations of motion. High speed computer graphics techniques provide realistic visual display for the simulator. A backhoe simulation is implemented as an example to demonstrate the feasibility of man-in-the-loop simulation on the low-cost simulator.
Dynamic Simulation of a Space Robot Hand-Off Procedure
Authors: Kim S. S. , Lin T.-C. , Haug E. J. , Frisch H. P. 
Published: April 2021

Abstract
Hand-off of an object from the flexible Remote Manipulator System (RMS) to the Flight Telerobot Servicer (FTS) in a space construction application is simulated. The application includes consideration of flexible multibody dynamics, control, and variable system topology. Position synchronization between the FTS end effector and a payload that is attached to the RMS is achieved by controlling the trajectory of the FTS end effector. Special position constraints and orientation rheonomic constraints are developed and imposed to simulate the object capture. Vibration suppression of the flexible arm is studied, using bang-bang controllers in the FTS.
Applications of Symbolic Computing for Numerical Analysis of Mechanical Systems
Authors: Ashrafiuon H. , Mani N. K. 
Published: April 2021

Abstract
The symbolic computing system MACSYMA is used to automatically generate the explicit equations necessary to represent the kinematic constraints and system dynamics and to compute the design sensitivities for optimal design of any multibody system. The logic to construct system matrices and vectors involved in the analysis and design equations is implemented as general purpose MACSYMA programs. All necessary manipulations are performed by MACSYMA and the equations are output as FORTRAN statements that can be compiled and executed. This approach results in a computational saving of up to 95% compared to using a general purpose programs. The approach is general in nature and is applicable to any multibody system. Examples are presented to demonstrate the effectiveness of the approach.
Tailoring of Composite Links for Optimal Damped Elasto-Dynamic Performance
Authors: Saravanos D. A. , Chamis C. C. 
Published: April 2021

Abstract
A method is developed for the optimal design of composite links based on dynamic performance criteria directly related to structural modal damping and dynamic stiffness. An integrated mechanics theory correlates structural composite damping to the parameters of basic composite material systems, laminate parameters, link shape, and modal deformations. The inclusion of modal properties allows the selective minimization of vibrations associated with specific modes. Ply angles and fiber volumes are tailored to obtain optimal combinations of damping and stiffness. Applications to simple composite links indicate wide margins for trade-offs and illustrate the importance of various design variables to the optimal design.
Design of Pitch Cones for Face-Hobbed Hypoid Gears
Authors: Litvin F. L. , Chaing W.-S. , Lundy M. , Tsung W.-J. 
Published: April 2021

Abstract
The authors proposed a method that allows the relations between the pitch cone angles and spiral angles to be determined directly. These relations are represented by a system of three nonlinear equations that are derived from: (i) conditions of tangency of the pitch cones and (ii) the specific location of the head—cutter that generates hypoid gears with face—hobbed teeth of uniform depth. A computer program for the determination of pitch cone parameters has been developed.
Equations have also been derived that allow to determine the location of apices of pitch cones with respect to the line of shortest distance, the coordinates of point of tangency of the pitch cones and the orientation of the plane that is tangent to the pitch cones. The proposed method is illustrated with a numerical example.
A Global Approach for Using Kinematic Redundancy to Minimize Base Reactions of Manipulators
Authors: Chung C. L. , Desa S. 
Published: April 2021

Abstract
An important consideration in the use of manipulators in Microgravity environments is the minimization of the base reactions, i.e. the magnitude of the force and the moment exerted by the manipulator on its base as it performs its tasks. One approach which has been proposed and implemented is to use the redundant degrees of freedom in a kinematically redundant manipulator to plan manipulator trajectories to minimize base reactions. In this paper we develop a global approach for minimizing the magnitude of the base reactions for kinematically redundant manipulators which integrates the Partitioned Jacobian method of redundancy resolution, a 4-3-4 joint-trajectory representation and the minimization of a cost function which is the time-integral of the magnitude of the base reactions. We also compare the global approach with a local approach developed earlier for the case of point-to-point motion of a three degree-of-freedom planar manipulator with one redundant degree-of-freedom. The results of study show that the global approach is more effective in reducing and smoothing the base force while the local approach is superior in reducing the base moment.
A Mechanics-Based Computer Algorithm for Displaying the Margin of Static Stability in Quadruped Walking Machines
Authors: Davidson J. K. , Schweitzer G. 
Published: April 2021

Abstract
The subject of this paper is the application of the mechanics of static stability to determine the potential upset of computer-controlled quadruped walking vehicles which are under development for use in very uneven terrain by the European construction and forestry industries. The margin of static stability is measured using normalized values for virtual power, each value corresponding to the motion about an axis of rotation which is associated with one mode of potential overturning. Static stability is treated for spatial positioning of the feet and for both three and four feet in contact with the ground. The inertial loads from a heavy tool, such as an excavating arm, are included in a quasi-static manner. The values for normalized virtual power are then related to a geometrical description of stability of the vehicle as if it were operating on level ground. Recommendations are made for visually displaying the geometrical description to the operator of the machine. The required measurements of force and position are listed.
A Unified Approach to the Kinematic Analysis of Joint Clearances and Link Length Tolerances for Determination of the Rotational and Positional Accuracy of Planar Mechanisms
Authors: Hoeltzel D. A. , Chiang W.-H. 
Published: April 2021

Abstract
A unified approach to the kinematic analysis of joint clearances and link length tolerances in general mechanisms is presented, expressly with the purpose of predicting the error in both rotational and positional accuracy of planar and spatial mechanisms. Rather than applying stochastic estimation or deterministically-based approximations based on a Taylor series expansion approach, this new method obtains the exact mechanical error based on a combination of approaches including the principle of virtual work, pertinent geometrical relations, and kinetostatic analysis. Computer–based kinematic designs for the Schmidt coupling, a parallel–jaw straight–line path generator and a sinusoidal function generator have been included as representative real–world design examples, for determination of their maximum mechanical error and error sensitivity to link length tolerances and joint clearances.
The computer–aided approach presented in this paper is particularly attuned to the needs and requirements of industrial precision mechanism designers in providing definitive information, which is directly applicable to the determination of kinematic error effects due to manufacturing tolerances, on the accuracy of mechanisms.
Topological Synthesis and Analysis of Geared Linkages Based on Matrix Powers
Authors: Olson D. G. , Erdman A. G. , Riley D. R. 
Published: April 2021

Abstract
A new method for transforming pin-jointed kinematic chains into geared linkages is introduced. The method utilizes the graph representation in the form of the adjacency matrix and the “degree matrix” [20], and the powers of these matrices. The method involves first determining the feasible locations for assigning gear pairs in a kinematic chain, followed by determining which of the choices are distinct, and finally, determining the distinct possible ways of assigning the ground link for each distinct “geared kinematic chain” so formed. Because the method is based on matrix manipulations and does not rely on visual inspection, it is easily implemented on a digital computer. The method is applied to an example class of geared mechanism, the single-dof geared seven-bar linkages.
Effect of Bearing Clearance on Cardan-Joint Kinematics
Authors: Fischer I. S. , Liu M. C. 
Published: April 2021

Abstract
The effect of radial bearing clearance at the intermediate joints of a Cardan-type universal joint has been investigated. It is found that errors in displacement at the output and also intermediate joints occur, and that their amplitudes have a linear relationship to the magnitudes of the radial bearing clearances.
A New Graph Representation for the Automatic Kinematic Analysis of Planetary Spur-Gear Trains
Authors: Hsu C.-H. , Lam K. T. 
Published: April 2021

Abstract
The purpose of this paper is to propose a new graph representation to represent the kinematic structure of a planetary spur-gear train efficiently. Based on the graph representation, the kinematic analysis of planetary spur-gear trains is largely simplified. An interactive computer program is developed for the kinematic analysis of planetary spur-gear trains with any numbers of degrees of freedom. By only inputting the graph representation of a planetary spur-gear trains and the data of the mating gear pairs, all possible fundamental circuits are determined and the rotational displacement equations are derived and solved automatically.
Four-Bar Path Generation Synthesis by a Continuation Method
Authors: Subbian T. , Flugrad D. R. 
Published: April 2021

Abstract
A different approach for the synthesis of four bar planar path generating mechanisms is presented. A continuation method is used to solve the system of nonlinear equations derived for the path generating problem. A brief description of the method is provided followed by the development of equations representing the four bar linkage. The implementation of the method for five position path generation is discussed in detail and the solutions for two examples are presented.
Pregnancy outcomes in women with a systemic right ventricle and transposition of the great arteries results from the ESC-EORP Registry of Pregnancy and Cardiac disease (ROPAC)
Authors: Tutarel Oktay , Baris Lucia , Budts Werner , Gamal Abd-El Aziz Mohamad , Liptai Csilla , Majdalany David , Jovanova Silvana , Frogoudaki Alexandra , Connolly Heidi M , Johnson Mark R , Maggioni Aldo P , Hall Roger , Roos-Hesselink Jolien W 
Published: April 2021

ObjectiveCardiac disease is a major cause of maternal mortality. Data regarding pregnancy outcomes in women with a systemic right ventricle (sRV) are scarce. We studied pregnancy outcomes in women with an sRV after the atrial switch procedure for transposition of the great arteries (TGA) or congenitally corrected TGA (CCTGA).MethodsThe ESC EORP Registry of Pregnancy and Cardiac Disease is an international prospective registry of pregnant women with cardiac disease. Pregnancy outcomes (maternal/fetal) in all women with an sRV are described. The primary end point was a major adverse cardiac event (MACE) defined as maternal death, supraventricular or ventricular arrhythmias requiring treatment, heart failure, aortic dissection, endocarditis, ischaemic coronary event and other thromboembolic events.ResultsAltogether, 162 women with an sRV (TGA n=121, CCTGA n=41, mean age 28.8±4.6 years) were included. No maternal mortality occurred. In 26 women, at least one MACE occurred, heart failure in 16 (9.8%), arrhythmias (atrial 5, ventricular 6) in 11 (6.7%) and others in 4 (2.5%). Prepregnancy signs of heart failure as well as an sRV ejection fraction <40% were predictors of MACE. One woman experienced fetal loss, while no neonatal mortality was observed. No significant differences were found between women with CCTGA and TGA. In the subset of women who had an echocardiogram before and after pregnancy, no clear deterioration in sRV was observed.ConclusionThe majority of women with an sRV tolerated pregnancy well with a favourable maternal and fetal outcome. Heart failure and arrhythmias were the most common MACE.
Trends in disability-free life expectancy at age 50 years in Australia between 2001 and 2011 by social disadvantage
Authors: Tawiah Richard , Jagger Carol , Anstey Kaarin J , Kiely Kim M 
Published: April 2021

BackgroundThe aims of this study were (1) to estimate 10-year trends in disability-free life expectancy (DFLE) by area-level social disadvantage and (2) to examine how incidence, recovery and mortality transitions contributed to these trends.MethodsData were drawn from the nationally representative Household Income and Labour Dynamics in Australia survey. Two cohorts (baseline age 50+ years) were followed up for 7 years, from 2001 to 2007 and from 2011 to 2017, respectively. Social disadvantage was indicated by the Socio-Economic Indexes for Areas (SEIFA). Two DFLEs based on a Global Activity Limitation Indicator (GALI) and difficulties with activities of daily living (ADLs) measured by the 36-Item Short Form Survey physical function subscale were estimated by cohort, sex and SEIFA tertile using multistate models.ResultsPersons residing in the low-advantage tertile had more years lived with GALI and ADL disability than those in high-advantage tertiles. Across the two cohorts, dynamic equilibrium for GALI disability was observed among men in mid-advantage and high-advantage tertiles, but expansion of GALI disability occurred in the low-advantage tertile. There was expansion of GALI disability for all women irrespective of their SEIFA tertile. Compression of ADL disability was observed for all men and for women in the high-advantage tertile. Compared to the 2001 cohort, disability incidence was lower for the 2011 cohort of men within mid-advantage and high-advantage tertiles, whereas recovery and disability-related mortality were lower for the 2011 cohort of women within the mid-advantage tertile.ConclusionOverall, compression of morbidity was more common in high-advantage areas, whereas expansion of morbidity was characteristic of low-advantage areas. Trends also varied by sex and disability severity.
A systematic study and literature review of parental somatic mosaicism of FBN1 pathogenic variants in Marfan syndrome
Authors: Fernández-Álvarez Paula , Codina-Sola Marta , Valenzuela Irene , Teixidó-Turá Gisela , Cueto-González Anna , Paramonov Ida , Antolín María , López-Grondona Fermina , Vendrell Teresa , Evangelista Artur , García-Arumí Elena , Tizzano Eduardo F 
Published: April 2021

BackgroundA proportion of de novo variants in patients affected by genetic disorders, particularly those with autosomal dominant (AD) inheritance, could be the consequence of somatic mosaicism in one of the progenitors. There is growing evidence that germline and somatic mosaicism are more common and play a greater role in genetic disorders than previously acknowledged. In Marfan syndrome (MFS), caused by pathogenic variants in the fibrillin-1 gene (FBN1) gene, approximately 25% of the disease-causing variants are reported as de novo. Only a few cases of parental mosaicism have been reported in MFS.MethodsEmploying an amplicon-based deep sequencing (ADS) method, we carried out a systematic analysis of 60 parents of 30 FBN1 positive, consecutive patients with MFS with an apparently de novo pathogenic variant.ResultsOut of the 60 parents studied (30 families), the majority (n=51, 85%) had a systemic score of 0, seven had a score of 1 and two a score of 2, all due to minor criteria common in the normal population. We detected two families with somatic mosaicism in one of the progenitors, with a rate of 6.6% (2/30) of apparently de novo cases.ConclusionsThe search for parental somatic mosaicism should be routinely implemented in de novo cases of MFS, to offer appropriate genetic and reproductive counselling as well as to reveal masked, isolated clinical signs of MFS in progenitors that may require specific follow-up.
BBS1 branchpoint variant is associated with non-syndromic retinitis pigmentosa
Authors: Fadaie Zeinab , Whelan Laura , Dockery Adrian , Li Catherina H Z , van den Born L Ingeborgh , Hoyng Carel B , Gilissen Christian , Corominas Jordi , Rowlands Charlie , Megaw Roly , Lampe Anne K , Cremers Frans P M , Farrar Gwyneth Jane , Ellingford Jamie M , Kenna Paul F. , Roosing Susanne 
Published: April 2021

BackgroundInherited retinal diseases (IRDs) can be caused by variants in >270 genes. The Bardet-Biedl syndrome 1 (BBS1) gene is one of these genes and may be associated with syndromic and non-syndromic autosomal recessive retinitis pigmentosa (RP). Here, we identified a branchpoint variant in BBS1 and assessed its pathogenicity by in vitro functional analysis.MethodsWhole genome sequencing was performed for three unrelated monoallelic BBS1 cases with non-syndromic RP. A fourth case received MGCM 105 gene panel analysis. Functional analysis using a midigene splice assay was performed for the putative pathogenic branchpoint variant in BBS1. After confirmation of its pathogenicity, patients were clinically re-evaluated, including assessment of non-ocular features of Bardet-Biedl syndrome.ResultsClinical assessments of probands showed that all individuals displayed non-syndromic RP with macular involvement. Through detailed variant analysis and prioritisation, two pathogenic variants in BBS1, the most common missense variant, c.1169T>G (p.(Met390Arg)), and a branchpoint variant, c.592-21A>T, were identified. Segregation analysis confirmed that in all families, probands were compound heterozygous for c.1169T>G and c.592-21A>T. Functional analysis of the branchpoint variant revealed a complex splicing defect including exon 8 and exon 7/8 skipping, and partial in-frame deletion of exon 8.ConclusionA putative severe branchpoint variant in BBS1, together with a mild missense variant, underlies non-syndromic RP in four unrelated individuals. To our knowledge, this is the first report of a pathogenic branchpoint variant in IRDs that results in a complex splice defect. In addition, this research highlights the importance of the analysis of non-coding regions in order to provide a conclusive molecular diagnosis.
Survival analysis of time to SARS-CoV-2 PCR negativisation to optimise PCR prescription in health workers: the Henares COVID-19 healthcare workers cohort study
Authors: González Martin-Moro Julio , Chamorro Gómez Marta , Dávila Fernández Galicia , Elices Apellaniz Ana , Fernández Hortelano Ana , Guzmán Almagro Elena , Herranz Varela Angela , Izquierdo Rodríguez Carlos , Molina Montes Beatriz , Sánchez Moreno Gema Vanesa , Mohedano-Gómez Alberto , Contreras Inés , González López Julio José 
Published: April 2021

ObjectivesReverse transcriptase PCR (RT-PCR) is considered the gold standard in diagnosing COVID-19. Infected healthcare workers do not go back to work until RT-PCR has demonstrated that the virus is no longer present in the upper respiratory tract. The aim of this study is to determine the most efficient time to perform RT-PCR prior to healthcare workers’ reincorporation.Materials and methodsThis is a cohort study of healthcare workers with RT-PCR-confirmed COVID-19. Data were collected using the medical charts of healthcare workers and completed with a telephone interview. Kaplan-Meier curves were used to determine the influence of several variables on the time to RT-PCR negativisation. The impact of the variables on survival was assessed using the Breslow test. A Cox regression model was developed including the associated variables.Results159 subjects with a positive RT-PCR out of 374 workers with suspected COVID-19 were included. The median time to negativisation was 25 days from symptom onset (IQR 20–35 days). Presence of IgG, dyspnoea, cough and throat pain were associated with significant longer time to negativisation. Cox logistic regression was used to adjust for confounding variables. Only dyspnoea and cough remained in the model as significant determinants of prolonged negativisation time. Adjusted HRs were 0.68 (0.48–096) for dyspnoea and 0.61 (0.42–0.88) for dry cough.ConclusionsRT-PCR during the first 3 weeks leads to a high percentage of positive results. In the presence of respiratory symptoms, negativisation took nearly 1 week more. Those who developed antibodies needed longer time to negativisate.