bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Formulations for Computing Design Propagations of the Spatial Slider-Crank Mechanism
Authors: Zou Hong-Liu , Abdel-Malek Karim , Wang Jia-Yi 
Published: February 2021

Abstract
A numerical formulation for studying the design of a spatial slider-crank mechanism is developed and illustrated. The mechanism is modeled using graph theory and closed loops are converted to a spanning tree structure by cutting joints and introducing new constraints. Variations of these constraints with respect to design parameters are derived. A change in link length or link orientation is propagated through the model and a new assembled configuration is computed hence redesigning the mechanism. Constraints are formulated in Cartesian space but computed in relative joint coordinate space. The Jacobian of the constraint is transformed to joint coordinate space in order to compute an assembled configuration for the cut-joint constraint formulation. The experimental code is illustrated through numerical examples where joint-position vectors and orientation matrices are altered.
On Steady-State Response of Multi-Cylinder Engine System
Authors: Shanshal Yassir , Farhang Kambiz 
Published: February 2021

Abstract
This paper deals with the rigid-body dynamic response of an internal combustion engine. An earlier work (Farhang and Midha, 1989) has presented an efficient algorithm for computing the steady-state rigid-body dynamic response of single degree of freedom engine systems. The method is utilized in the present work to examine the effects of spark time and combustion duration on the performance of a four-stroke, four-cylinder engine. In contrast with the earlier work in which combustion is viewed as an instantaneous process, in this work the combustion is accounted for and is related to the reference crank angle.
Robomech-III: A Stack of Three Four-Bar Chains for Triple-Function Task Applications
Authors: Smaili Ahmad , Rick Oliver 
Published: February 2021

Abstract
This paper presents Robomech-III, the third of a new class of linkage arms called robomechs. A robomech is a parallel architecture arm that combines features of a mechanism and a robot devised to perform coordinated multi-function tasks. In particular, Robomech-III is formed from a stack of three planar four-bar (4R) chain. This robomech requires three independently actuated joints to perform a specific triple-function task. The features of Robomech-III are discussed, a synthesis procedure is outlined and an application example is given.
A Framework for Closed-Form Displacement Analysis of Planar Mechanisms
Authors: Almadi Abdulaziz N. , Dhingra Anoop K. , Kohli Dilip 
Published: February 2021

Abstract
This paper presents a closed-form approach, based on theory of resultants, to the displacement analysis problem for n-link planar mechanisms. The proposed approach, called the method of successive elimination, generalizes Sylvester’s dialitic eliminant to the case when m equations (m ≥ 3) are to be solved in m unknowns. Conditions under which the method of successive elimination can be used to reduce m equations (in m unknowns) into a univariate polynomial, devoid of spurious roots, are presented. This univariate polynomial corresponds to the 1/0 polynomial of the mechanism. A comprehensive treatment is also presented on some of the problems associated with the conversion of transcendental loop-closure equations into an algebraic form using tangent-half-angle substitutions. It is shown how trigonometric manipulations in conjunction with tangent-half-angle substitutions can lead to extraneous roots in the solution process. Theoretical conditions for identifying and eliminating these spurious roots are presented. The computational procedure is illustrated through the displacement analysis of a 10-link SDOF mechanism which has 4 independent loops.
Design and Evaluation of Compliant Constant-Force Mechanisms
Authors: Millar Alisa J. , Howell Larry L. , Leonard James N. 
Published: February 2021

Abstract
Compliant constant-force mechanisms combine the effects of mechanical advantage and stored strain energy of flexible members to obtain constant output forces for a large range of input displacements. This paper extends and compliments previous work by accomplishing the following: i) dimensional synthesis is performed for a number of compliant constant-force mechanism configurations, ii) a simplified method of determining the magnitude of the constant output force is presented, and iii) experimental validation of the theory is addressed by reporting the results of testing three constant-force configurations. The results of i) and ii) are presented in a manner to be easily used by engineers designing such mechanisms. The results of iii) show that the mechanisms do follow a nearly constant force for a large input displacement, as predicted.
Dual Polynomials and Complex Dual Numbers for Analysis of Spatial Mechanisms
Authors: Cheng Harry H. , Thompson Sean 
Published: February 2021

Abstract
Complex dual numbers w̌1=x1+iy1+εu1+iεv1 which form a commutative ring are for the first time introduced in this paper. Arithmetic operations and functions of complex dual numbers are defined. Complex dual numbers are used to solve dual polynomial equations. It is shown that the singularities of a dual input-output displacement polynomial equation of a mechanism correspond to its singularity positions. This new method of identifying singularities provides clear physical insight into the geometry of the singular configurations of a mechanism, which is illustrated through analysis of special configurations of the RCCC spatial mechanism. Numerical solutions for dual polynomial equations and complex dual numbers are conveniently implemented in the CH language environment for analysis of the RCCC spatial mechanism. Like the dual number, the complex dual number is a useful mathematical tool for analytical and numerical treatment of spatial mechanisms.
Globally-Optimal Synthesis of Mechanisms for Path Generation Using Simulated Annealing and Powell’s Method
Authors: Ullah Irfan , Kota Sridhar 
Published: February 2021

Abstract
Success in synthesis of mechanisms for path generation usually depends on providing a good starting point to the optimizer. This paper presents a completely automatic method that performs a global search from a random starting point. A two-step synthesis process involves searching for a coupler curve of optimal shape followed by optimization of size, orientation, and position of the solution mechanism. For the first step, an objective function evaluating shape difference between two curves, irrespective of the differences in their sizes, orientation, and position, is defined based on Fourier descriptors of the curves. This function is minimized using a stochastic global search method derived from simulated annealing, followed by Powell’s method for fast convergence. In the second stage, using properties of Fourier descriptors, a set of points is located on the solution curve that is analogous to points specified on the desired curve. The size, orientation, and position of the solution mechanism is then determined by minimizing the distance between analogous points.
An Alternative Formulation of the Linkage-Type Long Dwell Mechanism Synthesis Problem
Authors: Ogot Madara M. , Aly Sherif 
Published: February 2021

Abstract
Dwell mechanisms are utilized extensively in machine tools, packaging and textile machinery, and machines used for the closing and labeling of cans. For numerous applications, exact dwells are not required facilitating the use of linkage-type dwell mechanisms which produce approximate dwells. The advantages which these mechanisms provide over cams include lower maintenance and manufacturing costs, superior performance at high speeds and higher reliability. Despite these advantages, dwell linkages, especially those with long dwells, are more difficult to design. For this study dwell is defined as long if it occurs for more than 30% of the linkage cycle. Current numeric optimization-based formulations which make use of precision points, often converge to high lying local minima or fail to converge to a solution at all, since the structural error-based objective functions are typically highly nonlinear and multi-modal functions in a multi-dimensional design space. The purpose of this paper, therefore, is the presentation of an optimization-based method which addresses this problem. The redefinition of the structural error-based objective function about precision lines instead of precision points, results in a more efficient search of the design space for optimal solutions. Use of precision lines maps symmetrical points in the design space to one point, thereby effectively shrinking the design space without any loss of information. As a result, superior solutions can be attained without requiring more computational effort than current optimization-based methods. The approach is tailored to the synthesis of linkage-type mechanisms with slider outputs and relatively long dwells. Two examples, a six-bar with a single dwell and a six-bar with a double dwell, are presented to illustrate the efficacy of the proposed formulation.
Computing Near Optimal Paths in C-Space Using Simulated Annealing
Authors: Martínez-Alfaro Horacio , Ulloa-Pérez Antonio 
Published: February 2021

Abstract
This article describes a minimum-distance collision-free path planning technique of an object among fixed obstacles. The workspace is represented in C-space which reduces the original problem to one of path planning for a point in an expanded-obstacle workspace. We use B-spline curves for path representation and they are synthesized with the Simulated Annealing algorithm. We also give representative 2D and 3D examples to validate our results.
An Algebraic-Geometrical Method for the Identification and Elimination of Circuit Defect
Authors: Beloiu Alexandru S. , Gupta Krishna C. 
Published: February 2021

Abstract
In this paper, an algebraic-geometrical method is proposed which unifies the resolution of the circuit defect, and full or partial input link rotatability in mechanism synthesis. The circuit defect is a gross motion defect. Starting from the follower link, the method develops algebraic curves of 20th order (H20 = 0), in a body reference system, which define the boundaries of the regions where the choice of the floating pin of the driving (input) link either would yield a mechanism free of branch and circuit defects, or most likely would yield potential-circuit-defective-mechanisms (PCDM). The point (B) representing the floating pin of the follower (BA) is a quadruple point of this curve. Therefore, polar rays passing through this point (B) yield from H20, effectively, a nontrivial polynomial in one variable of 16th order, thus simplifying the root finding problem. This analytical method also enables the unification of the PCDM regions with the branch defect regions (due to Filemon) and those for the design of mechanisms with transmission angle within prescribed limits (due to Gupta). The main conclusion is that to avoid branch and circuit defects, avoid the Filemon-defective regions as well as the portions of the PCDM-regions which lie in the Filemon-feasible regions. Interestingly, large portions of the PCDM-region are within the Filemon-defective region and are therefore easily excluded. It has been our experience that the circuit defect, which is a gross motion defect, does not occur frequently; in many examples, the entire PCDM-region was contained in the Filemon-defective region. However, the Filemon-feasible region may contain portions of the PCDM-region and this sub-region must be examined for potentially circuit defective mechanisms. The method is developed and illustrated with examples for the planar four-bar mechanisms, some of the numerical aspects of the solution are also discussed here.
The Effect of Creatine Supplementation on Markers of Exercise-Induced Muscle Damage: A Systematic Review and Meta-Analysis of Human Intervention Trials
Authors: Northeast Bethany , Clifford Tom 
Published: February 2021

This systematic review and meta-analysis examined the effects of creatine supplementation on recovery from exercise-induced muscle damage, and is reported according to the PRISMA guidelines. MEDLINE and SPORTDiscus were searched for articles from inception until April 2020. Inclusion criteria were adult participants (≥18 years); creatine provided before and/or after exercise versus a noncreatine comparator; measurement of muscle function recovery, muscle soreness, inflammation, myocellular protein efflux, oxidative stress; range of motion; randomized controlled trials in humans. Thirteen studies (totaling 278 participants; 235 males and 43 females; age range 20–60 years) were deemed eligible for analysis. Data extraction was performed independently by both authors. The Cochrane Collaboration Risk of Bias Tool was used to critically appraise the studies; forest plots were generated with random-effects model and standardized mean differences. Creatine supplementation did not alter muscle strength, muscle soreness, range of motion, or inflammation at each of the five follow-up times after exercise (<30 min, 24, 48, 72, and 96 hr; p > .05). Creatine attenuated creatine kinase activity at 48-hr postexercise (standardized mean difference: −1.06; 95% confidence interval [−1.97, −0.14]; p = .02) but at no other time points. High (I2; >75%) and significant (Chi2; p < .01) heterogeneity was identified for all outcome measures at various follow-up times. In conclusion, creatine supplementation does not accelerate recovery following exercise-induced muscle damage; however, well-controlled studies with higher sample sizes are warranted to verify these conclusions. Systematic review registration (PROSPERO CRD42020178735).
Relationships Between Different Internal and External Training Load Variables and Elite International Women’s Basketball Performance
Authors: Coyne Joseph O.C. , Coutts Aaron J. , Newton Robert U. , Gregory Haff G. 
Published: February 2021

Purpose: To investigate the relationships between internal and external training load (TL) metrics with elite international women’s basketball performance. Methods: Sessional ratings of perceived exertion, PlayerLoad™/minute, and training duration were collected from 13 elite international-level female basketball athletes (age 29.0 [3.7] y, stature 186.0 [9.8] cm, body mass 77.9 [11.6] kg) during the 18 weeks prior to the International Basketball Federation Olympic qualifying event for the 2016 Rio Olympic Games. Training stress balance, differential load, and the training efficiency index were calculated with 3 different smoothing methods. These TL metrics and their change in the last 21 days prior to competition were examined for their relationship to competition performance as coach ratings of performance. Results: For a number of TL variables, there were consistent significant small to moderate correlations with performance and significant small to large differences between successful and unsuccessful performances. However, these differences were only evident for external TL when using exponentially weighted moving averages to calculate TL. The variable that seemed most sensitive to performance was the change in training efficiency index in the last 21 days prior to competition (performance r = .47–.56, P < .001 and difference between successful and unsuccessful performance P < .001, f2 = 0.305–0.431). Conclusions: Internal and external TL variables were correlated with performance and distinguished between successful and unsuccessful performances among the same players during international women’s basketball games. Manipulating TL in the last 3 weeks prior to competition may be worthwhile for basketball players’ performance, especially in internal TL.
Reconstructing drainage pathways in the North Atlantic during the Triassic utilizing heavy minerals, mineral chemistry, and detrital zircon geochronology
Authors: Andrews Steven D. , Morton Andrew , Decou Audrey , Frei Dirk 
Published: February 2021

AbstractIn this study, single-grain mineral geochemistry, detrital zircon geochronology, and conventional heavy-mineral analysis are used to elucidate sediment transport pathways that existed in the North Atlantic region during the Triassic. The presence of lateral and axial drainage systems is identified and their source regions are constrained.Axial systems are suggested to have likely delivered sediment sourced in East Greenland (Milne Land–Renland) as far south as the south Viking Graben (&gt;800 km). Furthermore, the data highlight the existence of lateral systems issuing from Western Norway and the Shetland Platform as well as a major east-west–aligned drainage divide positioned adjacent to the Milne Land–Renland region. This divide separated the catchments that flowed north to the Boreal Ocean from those that flowed south into a series of endoreic basins and, ultimately, the Tethys Sea. A further potential drainage divide is identified to the west of Shetland.The data presented and the conclusions reached have major implications for reservoir prediction, as well as correlation, throughout the region. Furthermore, understanding the drainage networks that existed during the Triassic can help constrain paleogeographic reconstructions and provides an important framework for the construction of facies models in the region.
Detrital sanidine 40Ar/39Ar dating confirms &lt;2 Ma age of Crooked Ridge paleoriver and subsequent deep denudation of the southwestern Colorado Plateau
Authors: Heizler Matthew T. , Karlstrom Karl E. , Albonico Micael , Hereford Richard , Beard L. Sue , Cather Steven M. , Crossey Laurie J. , Sundell Kurt E. 
Published: February 2021

AbstractCrooked Ridge and White Mesa in northeastern Arizona (southwestern United States) preserve, as inverted topography, a 57-km-long abandoned alluvial system near the present drainage divide between the Colorado, San Juan, and Little Colorado Rivers. The pathway of this paleoriver, flowing southwest toward eastern Grand Canyon, has led to provocative alternative models for its potential importance in carving Grand Canyon. The ∼50-m-thick White Mesa alluvium is the only datable record of this paleoriver system. We present new 40Ar/39Ar sanidine dating that confirms a ca. 2 Ma maximum depositional age for White Mesa alluvium, supported by a large mode (n = 42) of dates from 2.06 to 1.76 Ma. Older grain modes show abundant 37–23 Ma grains mostly derived ultimately from the San Juan Mountains, as is also documented by rare volcanic and basement pebbles in the White Mesa alluvium. A tuff with an age of 1.07 ± 0.05 Ma is inset below, and hence provides a younger age bracket for the White Mesa alluvium. Newly dated remnant deposits on Black Mesa contain similar 37–23 Ma grains and exotic pebbles, plus a large mode (n = 71) of 9.052 ± 0.003 Ma sanidine. These deposits could be part of the White Mesa alluvium without any Pleistocene grains, but new detrital sanidine data from the upper Bidahochi Formation near Ganado, Arizona, have similar maximum depositional ages of 11.0–6.1 Ma and show similar 40–20 Ma San Juan Mountains–derived sanidine. Thus, we tentatively interpret the &lt;9 Ma Black Mesa deposit to be a remnant of an 11–6 Ma Bidahochi alluvial system derived from the now-eroded southwestern fringe of the San Juan Mountains. This alluvial fringe is the probable source for reworking of 40–20 Ma detrital sanidine and exotic clasts into Oligocene Chuska Sandstone, Miocene Bidahochi Formation, and ultimately into the &lt;2 Ma White Mesa alluvium. The &lt;2 Ma age of the White Mesa alluvium does not support models that the Crooked Ridge paleoriver originated as a late Oligocene to Miocene San Juan River that ultimately carved across the Kaibab uplift. Instead, we interpret the Crooked Ridge paleoriver as a 1.9–1.1 Ma tributary to the Little Colorado River, analogous to modern-day Moenkopi Wash. We reject the “young sediment in old paleovalley” hypothesis based on mapping, stratigraphic, and geomorphic constraints. Deep exhumation and beheading by tributaries of the San Juan and Colorado Rivers caused the Crooked Ridge paleotributary to be abandoned between 1.9 and 1.1 Ma. Thermochronologic data also provide no evidence for, and pose substantial difficulties with, the hypothesis for an earlier (Oligocene–Miocene) Colorado–San Juan paleoriver system that flowed along the Crooked Ridge pathway and carved across the Kaibab uplift.
Adjuvant corticosteroids for prevention of kidney scarring in children with acute pyelonephritis: a systematic review and meta-analysis
Authors: Meena Jitendra , Kumar Jogender 
Published: February 2021

BackgroundAcute pyelonephritis in children may result in permanent kidney scarring that is primarily caused by inflammation during acute infection. Antibiotic therapy alone is not enough to significantly reduce kidney scarring, and adjuvant corticosteroid therapy has shown a significant reduction in inflammatory cytokines in urine prompting its evaluation in randomised controlled trials. A few clinical trials showed a trend towards a reduction in renal scarring but did not have an adequate sample size to show a significant effect. Therefore, we planned to synthesise the available evidence on the role of corticosteroids as adjuvant therapy in reducing kidney scarring.ObjectiveTo assess the efficacy and safety of adjuvant corticosteroid therapy for the prevention of kidney scarring in children with acute pyelonephritis.DesignSystematic review and meta-analysis.SettingCommunity-acquired febrile urinary tract infections.PatientsChildren (less than 18 years) with acute pyelonephritis.InterventionAdjuvant corticosteroid therapy (along with antibiotic treatment).Main outcome measuresPrimary: efficacy in preventing kidney scarring; secondary: serious adverse events associated with corticosteroid therapy.ResultsThree randomised trials (529 children) were included. Corticosteroids are effective in lowering the risk of kidney scarring as compared with placebo (risk ratio (RR): 0.57; 95% CI 0.36 to 0.90). No significant increase risk of bacteraemia (RR: 1.38; 95% CI 0.23 to 8.23) and hospitalisation (RR: 0.87; 95% CI 0.3 to 2.55) was observed in corticosteroid group.ConclusionModerate quality evidence suggests that short duration ‘adjuvant corticosteroid therapy’ along with routine antibiotic therapy in acute febrile urinary tract infection significantly reduces the risk of kidney scarring without any significant adverse effects.