bluuebunny/crossref_metadata_2025_split huggingface dataset:
Singularities in Motion and Displacement Functions for the RCRCR RCRRC and RSRC Linkages: Part I — Basic Concepts
Authors: Litvin F. L. , Tan J. , Fanghella P. , Wu S. 
Published: April 2021

Abstract
A new approach for the determination of singularities in motion of spatial linkages, displacement functions and the number of linkage configurations is proposed. Singularities in motion occur at positions where an overconstrained group of links become movable at least locally while the driving link is fixed. The determination of displacement functions is based on modeling of the linkage by two open kinematic chains formed: (i) by links of an overconstrained group of links and (ii) the driving link and the frame. Conditions of “assembly” of the open chains provide invariants-scalar products-that yield the appropriate equations that relate the parameters in motion of the driving link and the overconstrained group of links. The number of linkage configurations is proposed to determine through the number of singularity positions that are simulated with a certain combination of the linkage design parameters. Applications of the proposed approach to the RCRCR, RCRRC and RSRC linkages are represented in the following parts 2, 3 and 4 of the paper.
Singularities in Motion and Displacement Functions for the RCRCR, RCRRC and RSRC Linkages: Part II — The RCRCR Linkage
Authors: Litvin F. L. , Tan J. 
Published: April 2021

Abstract
The general approach for the determination of singularities in motion and displacement functions for spatial linkages has been developed by Litvin, et al. (1986) and represented in the first part of this paper. Applications of the developed methods for the RCRCR linkage are given in this paper. The authors have determined the singularities in motion, displacement functions and the configurations of the linkage. Numerical examples are given.
Singularities in Motion and Displacement Functions for the RCRCR, RCRRC and RSRC Linkages: Part IV — The RSRC Linkage
Authors: Litvin F. L. , Wu S. 
Published: April 2021

Abstract
The basic ideas of this paper are based on the following considerations (see Litvin, et al., 1986, and Part I of this paper): (i) Singularities in motion occur at positions where the overconstrained group that is formed by links 2 and 3 becomes movable with respect to links 1 and 4 while the driving link 1 is held at rest (link 4 is the frame). (ii) The displacement functions are determined by modeling the linkage by two open kinematic chains. Configurations of the linkage are discussed. Numerical examples are given.
The Image Curve of the Motion of the Planet in a Spherical Epicyclic Gear Train
Authors: Ge Q. , McCarthy J. M. 
Published: April 2021

Abstract
This paper uses the Euler parameters of the motion of the planet of a spherical epicyclic gear train to obtain a curve on the surface of a hypersphere in four dimensions. This curve, called the image curve, represents the rotational motion of the planet as it rolls without slipping on the fixed gear. Two image curves are obtained for two different choices of moving and fixed reference frames and it is shown that they are related by an orthogonal transformation in four dimensional space. The differential properties of the image curve are computed and it is found that the curvature is constant and the torsion is periodic in the motion parameter. A reference position is chosen and the canonical frame and instantaneous invariants of the motion are determined in terms of the dimensions of the gear train.
A Substructure Technique for Dynamics of Flexible Mechanical Systems With Contact-Impact
Authors: Wu S.-C. , Haug E. J. 
Published: April 2021

Abstract
A substructure synthesis method is proposed to account for contact-impact effects in flexible components of mechanical systems. Components that may come into contact is divided into substructures, on each of which local deformation modes are defined to described deformation fields of components. Constraint modes and fixed interface normal modes are used to account for elastic deformation within each substructure. A constraint addition-deletion technique is used to account for contact between impacting bodies. Lagrange multipliers associated with the constraints, which represent constraint forces, are used to determine separation of contacting nodes. Use of the method is illustrated on problems of longitudinal and transverse impact of bodies.
Selection of Deformation Modes for Flexible Multibody Dynamics
Authors: Kim S.-S. , Haug E. J. 
Published: April 2021

Abstract
This paper presents a method of selecting boundary conditions and deformation modes for redundantly constrained flexible components in mechanical system dynamics. Gaussian elimination is used to partition the coefficient matrix in equilibrium equations for each flexible component, leading to definition of a retained statically determinate set and a redundant set of boundary conditions. Methods for selection of deformation modes is presented, to account for deformation due to constraint reaction forces. A door closing mechanism and a moving flexible beam illustrate the method of selecting boundary conditions and the effectiveness of constraint modes for approximation for system dynamic response.
Some Issues in the Generation of the Topology of Systems With Constant Power-Flow Input-Output Requirements
Authors: Prabhu D. R. , Taylor D. L. 
Published: April 2021

Abstract
In this paper, we examine design problems in which requirements consist of constant power-flows with constant effort and flow variables in various domains. The use of an outgrowth of bond graph structure for design is explored. A spanning set of functional primitives is determined which can assemble an arbitrary system meeting the above functional requirements. Some basic theorems are developed regarding generic assembly algorithms to build systems using elements belonging to the chosen set. Maximum and minimum bounds on complexity are determined. An optimal partitioning of specified requirements is obtained to minimize the number of primitives needed. Power-flows through each primitive used is subsequently minimized to obtain a minimal power-flow graph.
A Separating Channel Decomposition Algorithm for Non-Convex Polygons With Application in Interference Detection
Authors: Ku T. S. , Ravani B. 
Published: April 2021

Abstract
An algorithm for efficient decomposition of interface channels between non-convex polygons in a Computer-Aided Design (CAD) environment is presented. This algorithm forms the computational basis for the solution of several design automation problems. In this paper, the channel decomposition algorithm is presented and applied to the problem of interference detection between non-convex polygons. The resulting interference detection algorithm does not require preprocessing of the data and uses a simple data structure. In a companion paper (Ku and Ravani 1988), the channel decomposition algorithm is applied to the problem of model-based rigid-body guidance in presence of geometric constraints.
Optimal Design of Wind Turbines Using BIAS, A Method of Multipliers Code
Authors: Vick B. D. , Wrigglesworth W. , Scott L. B. , Ragsdell K. M. 
Published: April 2021

Abstract
A method has been developed and is demonstrated which determines the chord and twist distribution for a wind turbine with maximum power coefficient. Only small wind turbines (less than 10 kilowatts) are considered in this study, but the method could be used for larger wind turbines. Glauert determined a method for estimating the chord and twist distribution that will maximize the power coefficient if there is no drag. However, the method proposed here determines the chord and twist distribution which will maximize the power coefficient with the effect of drag included. Including drag in the analysis does not significantly affect the Glauert chord and twist distribution for airfoils with a high lift coefficient at the maximum lift to drag ratio. However, if the airfoil has a fairly low lift coefficient at its maximum lift to drag ratio due to its shape or a rough surface then significant improvement can be obtained in power coefficient by altering the Glauert chord and twist distribution according to the method proposed herein.
Part Layout Optimization Using a Quadtree Representation
Authors: Sandgren E. , Dworak T. 
Published: April 2021

Abstract
A nonlinear programming formulation is developed for minimizing the area required to position a set of pre-defined objects without overlap. The objects consist of polygons with an arbitrary number of edges. Nonconvex polygons are assumed which allows for the modelling of complex parts, including parte with holes. A quadtree representation is formed for each polygon and intersections are determined by traversing quadtrees for the potentially intersecting objects. The design variables are selected to be the x and y location and the rotation for each polygon that is to be positioned. An exterior penalty function method is used to generate the solution to the resulting nonlinear programming problem. A nongradient search technique is used due to the discrete nature of the overlap constraints. Example problems are presented and extensions to other classes of problems are discussed.
Optimal Design of Mechanisms Using Simulated Annealing: Theory and Applications
Authors: Jain P. , Agogino A. M. 
Published: April 2021

Abstract
A new approach to optimization in kinematic synthesis of mechanisms is presented which is based on simulated annealing, a probabilistic combinatorial optimization technique. The advantage of this technique is that it converges to the global optimum asymptotically. Simulated annealing has been successfully applied to solve several combinatorial optimization problems in the fields of computer-aided design of VLSI chips, image processing and graph theory. However, it has not been used as an optimization tool in the field of mechanical design. We solve three problems in kinematic synthesis using simulated annealing and the results show that the method is fast and obtains solutions at least as good as and in some cases better than those obtained by conventional optimization techniques.
Optimum Synthesis of Thin-Walled Vibrating Beams With Coupled Bending and Torsion
Authors: Grandhi R. V. , Moradmand J. K. 
Published: April 2021

Abstract
This paper considers the optimum structural design of vibrating beams in which the inertial axes and the elastic axes are non-collinear. The condition of non-collinear axes exists in structures having unsymmetric cross-sections. For unsymmetric crose-sections the centroid and the shear center do not coincide. This results in coupling between some of the bending and torsional modes. This paper presents results for the simply supported and cantilever beams with a thin-walled channel cross-section. The minimization of the structural volume subject to multiple frequency constraints and its dual problem of maximization of the fundamental frequency subject to a volume constraint are considered. A quadratic extended interior penalty function with Newton’s method of unconstrained minimization is used in structural optimization. The structures considered have non-structural masses besides their own mass.
A Generalized Expert System Shell for Implementing Mechanical Design Applications: Review, Introduction and Fundamental Concepts
Authors: Premkumar P. , Kramer S. N. 
Published: April 2021

Abstract
The foundations for an expert system shell for implementing mechanical design applications are presented in this paper. The shell supports facilities for knowledge acquisition, quasi-reactive planning, design evaluation, and subjective explanation. The underlying philosophy of each of these facilities and some preliminary implementation issues are discussed. A brief summary of a recent research effort and its implications on the development of a generalized expert system shell for implementing mechanical design applications are also presented.
A Graphical, User-Driven Newton-Raphson Technique for Use in the Analysis and Design of Compliant Mechanisms
Authors: Hill T. C. , Midha A. 
Published: April 2021

Abstract
The analysis and design of compliant mechanisms, undergoing large (geometrically nonlinear) deflections, have been assisted by the Newton-Raphson method to find the loads which satisfy a prescribed set of force and displacement boundary conditions. This paper introduces a graphical, user-driven Newton-Raphson technique that allows easy access to good initial design variable estimates, and subsequently accurate and expeditious solutions. These design variables may include loads as well as material and geometric properties of the beam segments composing the mechanism. A line search step-restriction technique is included to enhance the stability of the method. The method uses six-degree-of-freedom planar beam elements in a chain calculation that cumulatively evaluates the large deflections corresponding to a given load set.
Limitations of Conjugate Gear Tooth Surfaces in Order to Avoid Undercutting and Appearance of Envelope of Lines of Contact
Authors: Litvin F. L. , Kin D. J. , Zhang Y. 
Published: April 2021

Abstract
Gear tooth surfaces being in line contact at every instant are considered. The dimensions of the contacting surfaces must be limited in order to avoid: (i) the appearance of the envelope of lines of contact on the generating surface Σ1 and (ii) the appearance of singular points on the generated surface Σ2. The relations between the developed concepts and the Wildhaber’s concept of the limiting pressure angle are investigated. Applications to the worm-gear drive and the generation of a pinion of a formate gear drive are considered. Computer graphics have been used to illustrate the results of computation.
A Recursive Formulation for Real-Time Dynamic Simulation
Authors: Bae D.-S. , Hwang R. S. , Haug E. J. 
Published: April 2021

Abstract
A new recursive algorithm for real-time, interactive dynamic simulation, animated graphics, and design variation analysis is presented for mechanical systems with closed loops. State vector kinematic relations that represent translational and rotational motion are defined, to simplify the formulation and to relieve computational burden. Recursive equations of motion are first derived for a single loop multi-body system. Faster than real-time performance is demonstrated for a closed loop robot, using an Alliant FX/8 multiprocessor. The algorithm is extended to multi-loop, multi-body systems for parallel processing real-time simulation in companion papers [1,2]. Performance of the algorithm on a shared memory multi-processor is compared with that achieved with other dynamic simulation algorithms. A vehicle example is used to demonstrate efficiency of the algorithm for real-time simulation and graphics rendering in a network environment, for use as an interactive design tool.
Clinical characteristics of full thickness macular holes that closed without surgery
Authors: Uwaydat Sami H , Mansour Ahmad , Ascaso Francisco J , Parodi Maurizio Battaglia , Foster Robert , Smiddy William E , Schwartz Stephen G , Charbaji Abdulrazzak , Belotto Silvana , Jürgens Ignasi , Mateo Javier , Ellabban Abdallah A , Wu Lihteh , Figueroa Marta , Olivier Pascual Nuria , Lima Luiz H , Alsakran Wael A , Caliskan Kadayifcilar Sibel , Sinawat Suthasinee , Assi Alexandre , Mansour Hana A , Casella Antonio Marcello , Navea Amparo , Neila Elena Rodríguez , Saatci A Osman , Govindahari Vishal , Esteban Floria Olivia , Agarwal Komal , Bakkali El Bakkali Ismael , Alaman Angel Salinas , Larripa Sofia Fernandez , Rey Amanda , Pera Patricia , Bruix Lluís , Lopez-Guajardo Lorenzo , Pérez-Salvador Eduardo , Lara Medina Francisco Javier , Hrisomalos Frank N , Chhablani Jay , Arevalo J Fernando 
Published: April 2021

PurposeTo ascertain the anatomic factors that help achieve non-surgical sealing in full thickness macular hole (FTMH).MethodsRetrospective collaborative study of FTMH that closed without surgical intervention.ResultsA total of 78 patients (mean age 57.9 years) included 18 patients with blunt ocular trauma, 18 patients that received topical or intravitreal therapies and 42 patients with idiopathic FTMH. Mean±SD of the initial corrected visual acuity (VA) in logMAR improved from 0.65±0.54 to 0.34±0.45 (p<0.001) at a mean follow-up of 33.8±37.1 months. FTMH reopened in seven eyes (9.0%) after a mean of 8.6 months. Vitreomacular traction was noted in 12 eyes (15.8%), perifoveal posterior vitreous detachment in 42 (53.8%), foveal epiretinal membrane in 10 (12.8%), cystoid macular oedema (CME) in 49 (62.8%) and subretinal fluid (SRF) in 20 (25.6%). By multivariate analysis, initial VA correlated to the height (p<0.001) and narrowest diameter of the hole (p<0.001) while final VA correlated to the basal diameter (p<0.001). Time for closure of FTMH (median 2.8 months) correlated to the narrowest diameter (p<0.001) and the presence of SRF (p=0.001). Mean time for closure (in months) was 1.6 for eyes with trauma, 4.3 for eyes without trauma but with therapy for CME, 4.4 for eyes without trauma and without therapy in less than 200 µm in size and 24.7 for more than 200 µm.ConclusionOur data suggest an observation period in new onset FTMH for non-surgical closure, in the setting of trauma, treatment of CME and size <200 µm.
Perception of obesity and overweight among adults living in suburban Nepal: a qualitative study
Authors: Shrestha Sachita , Asthanee Shanta , Karmacharya Biraj Man , Subedi Seema , Koju Rajendra 
Published: April 2021

ObjectiveTo explore the perception of obesity and overweight among Nepalese adults living in a suburban community.DesignA qualitative study composed of focus group discussion (FGD) and in-depth interview (IDI).SettingCommunity and healthcare facilities in Dhulikhel, Nepal.ParticipantsFour FGDs were conducted with community members (n=22) and four IDIs were conducted with healthcare providers (HCPs).ResultsObesity is a rising problem in this suburban community. Participants had inadequate knowledge regarding the consequences of obesity, and they perceived overweight as normal, healthy and attractive. The participants above 40 years of age did not perceive themselves to be overweight or obese. Despite participants’ awareness of the importance of diet control and exercise to prevent obesity, these were not translated into practice.ConclusionsThis study provided insight into perceptions of obesity in a suburban Dhulikhel community through both community members’ and HCPs’ perspective. Misconceptions and inadequate knowledge of obesity among people in this community indicate the need for health education and intervention programme to increase health awareness and preventive practices.
Influence of childhood trauma on the treatment outcomes of pharmacological and/or psychological interventions for adolescents and adults with bipolar disorder: protocol for a systematic review and meta-analysis
Authors: Wrobel Anna , Russell Samantha E , Dean Olivia M , Cotton Sue , Berk Michael , Turner Alyna 
Published: April 2021

IntroductionDespite available pharmacological and psychological treatments, remission rates for bipolar disorder remain relatively low. Current research implicates the experience of childhood trauma as a potential moderator of poor treatment outcomes among individuals with bipolar disorder. To date, the evidence reporting the influence of childhood trauma on the treatment outcomes of pharmacological and/or psychological interventions for adolescents and adults with bipolar disorder has not been systematically reviewed.Method and analysisMEDLINE Complete, Embase, PsycINFO and the Cochrane Central Register of Controlled Trials will be searched to identify randomised and nonrandomised studies of pharmacological and/or psychological interventions for bipolar disorder, which also assessed childhood trauma. To be eligible for inclusion, studies must have been conducted with adolescents or adults (≥10 years). Data will be screened and extracted by two independent reviewers. The methodological quality of the included studies will be assessed with the Cochrane Collaboration’s Risk of Bias tool and the Newcastle-Ottawa Scale. If deemed viable, a meta-analysis will be conducted using a random effects model. Heterogeneity of evidence will be estimated with the I² statistics.Ethics and disseminationThis systematic review will use only previously published data. Therefore, ethical approval is not required. The results will be written in concordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines, published in peer-reviewed journals and presented at relevant conferences.PROSPERO registration numberCRD42020201891.
Cost-effectiveness of emergency preparedness measures in response to infectious respiratory disease outbreaks: a systematic review and econometric analysis
Authors: Vardavas Constantine , Nikitara Katerina , Zisis Konstantinos , Athanasakis Konstantinos , Phalkey Revati , Leonardi-Bee Jo , Johnson Helen , Tsolova Svetla , Ciotti Massimo , Suk Jonathan E 
Published: April 2021

ObjectivesRespiratory infectious disease outbreaks pose a threat for loss of life, economic instability and social disruption. We conducted a systematic review of published econometric analyses to assess the direct and indirect costs of infectious respiratory disease outbreaks that occurred between 2003 and 2019.SettingRespiratory infectious disease outbreaks or public health preparedness measures or interventions responding to respiratory outbreaks in OECD countries (excluding South Korea and Japan) so as to assess studies relevant to the European context. The cost-effectiveness of interventions was assessed through a dominance ranking matrix approach. All cost data were adjusted to the 2017 Euro, with interventions compared with the null. We included data from 17 econometric studies.Primary and secondary outcome measuresDirect and indirect costs for disease and preparedness and/or response or cost-benefit and cost-utility were measured.ResultsOverall, the economic burden of infectious respiratory disease outbreaks was found to be significant to healthcare systems and society. Indirect costs were greater than direct costs mainly due to losses of productivity. With regard to non-pharmaceutical strategies, prehospitalisation screening and the use of protective masks were identified as both an effective strategy and cost-saving. Community contact reduction was effective but had ambiguous results for cost saving. School closure was an effective measure, but not cost-saving in the long term. Targeted antiviral prophylaxis was the most cost-saving and effective pharmaceutical intervention.ConclusionsOur cost analysis results provide evidence to policymakers on the cost-effectiveness of pharmaceutical and non-pharmaceutical intervention strategies which may be applied to mitigate or respond to infectious respiratory disease outbreaks.