bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Orthogonal-Decomposition Algorithm for Constrained Least-Square Optimization
Authors: Angeles J. , Anderson K. , Gosselin C. 
Published: April 2021

Abstract
The problem of minimizing a positive definite quadratic performance index of a m-dimensional nonlinear vector function of n design variables, subject to p nonlinear equality constraints is addressed in this paper. First the simple case in which the performance index is quadratic in the design variables, and the constraints are linear is dealt with. Based on this, an iterative procedure is derived for the more general case in which the performance is not quadratic and the constraints are nonlinear.
Synthesis of Linkages to Generate Specified Histories of Forces and Torques: The Planar Slider-Crank Mechanism
Authors: Bagci C. 
Published: April 2021

Abstract
The first part of the article presented analytical precision and optimum synthesis methods for linkages for the generation of specified torque histories and applied to the planar 4R four-bar mechanism. This article presents analytical mechanical advantage method (MAM) and integration of power equilibrium method (IPEM) for the synthesis of the planar slider-crank mechanism for the generation of specified input-output force and torque histories. Design equations for one, two, three, and four precision position synthesis are given. They are used to formulate the optimum synthesis technique, which requires no iteration to reach a solution mechanism. Slider-crank mechanisms synthesized also replace pinion-rack drives with noncircular and circular pinions to generate non-uniform and uniform velocity ratios, respectively. The MAM can be applied for discretely defined and continuous force-torque relationships, while IPEM is used with continuous relationships which reduces the force-torque generation into an elementary function generation problem. Application examples are included.
On the Derivation of Grashof-Type Moveability Conditions With Transmission Angle Control for Spatial Mechanisms
Authors: Rastegar J. 
Published: April 2021

Abstract
Derivation of Grashof-type conditions for spatial mechanisms that may include transmission angle limitations are discussed. It is shown that in general, different conditions need to be derived for each one of the existing configurations of the mechanism. In the absence of any transmission angle control, the conditions would be identical for pairs of configurations. As an example, for RRRSR mechanisms, Grashof-type conditions that ensure crank rotatability, the existence of a drag link type of mechanism, single or multiple changeover points, the possibility of full rotation at intermediate revolute joints, etc., are determined. A general discussion of the problems involved in such derivations, the use of approximation techniques to overcome some of the problems, and several other related subjects are presented.
Inverse Kinematics Solutions for General Spatial Linkages
Authors: Tucker M. , Perreira N. D. 
Published: April 2021

Abstract
A procedure for obtaining solutions to the general inverse kinematics problem for both position and velocity is presented. Solutions to this problem are required for improved robot control and linkage synthesis. The procedure requires obtaining the inverse of the actual robot linkage Jacobian. A procedure to detect the presence of singularities in the Jacobians and their causes are given. Inverse solution techniques applicable to robots with less than, equal to, or greater than six degrees of freedom and their implementation to robots with various types of singularities is outlined. For each case, the implementation of both the complete Moore-Penrose inverse and a robot specific pseudo inverse are included. Although it is not necessary to use the complete Moore-Penrose inverse on any particular robot, it can be used to obtain generic inverse routines for general purpose applications.
The Image of the Coupler Motion of a Special Spherical Four Bar Linkage
Authors: McCarthy J. M. 
Published: April 2021

Abstract
This paper uses a kinematic mapping of spherical motion to derive an image curve which represents the coupler motion of a doubly folding spherical four bar linkage. The image curve of this linkage, the so called “kite” linkage, can be parameterized by rational functions. This parameterization is presented as well as formulas which allow the computation of its curvature and torsion at any point. These formulas provide a link between the global properties of the coupler motion as represented by the image curve itself and its instantaneous properties given by the curvature and torsion functions.
Design of Radial Cams With Zero Pressure Angle
Authors: Fenton R. G. , Zhenbiao Wu 
Published: April 2021

Abstract
The addition of an intermediate roller between the cam and the follower roller is proposed in this paper. The function of this intermediate roller is to reduce the pressure angle on the follower to zero. As a result of adding the proposed intermediate roller, all problems caused by the pressure angle in cam mechanisms are eliminated.
Quadratic Time Increment Indexing for Stepper Motor Motion Control
Authors: Savage M. , Grover J. E. 
Published: April 2021

Abstract
A fundamental problem of mechanical motion control is that of indexing a mass reliably from one stationary position to another in a given time with as little power as possible. A quadratic time increment function is proposed and demonstrated for stepping motor control. With this function, a given motor can index a mass through a variety of index lengths. The indexing system includes a microprocessor to adjust the motor pulse timing to index the inertial load through a range of motions — each with the same maximum torque. The functions and the sizing of the motor are described. The interaction between the microprocessor calculation speed and the indexing capability is given for achievable real time control. Experimental results for a specific system are presented.
Hypotrochoidal Versus Epitrochoidal Gerotor Type Pumps With Special Attention to Volume Change Ratio and Size
Authors: Beard J. E. , Hall A. S. , Soedel W. 
Published: April 2021

Abstract
The planar rotary mechanism, by virtue of its volume changing ability can be used as a pump, engine or compressor. Most of the types of rotary mechanisms used today, from the Wankel rotary engine to the gerotor pump, are based on epitrochoidal generation and its conjugate shape. This paper presents the mathematical relationships for the hypotrochoidal generation and also compares the flow rate, pocket and pump displacement between the hypotrochoidal and epitrochoidal generated profiles.
An Experimental Investigation of the Dynamic Response of a Mechanical System With Bearing Clearance
Authors: Soong K. , Thompson B. S. 
Published: April 2021

Abstract
Numerous publications have been devoted to the development of analytical and computational models for predicting the dynamic response of mechanical systems comprising assemblages of rigid-bodies with clearance at the joints. However, there is a dearth of experimental investigations in this area which focus on furnishing complementary response data, consequently the predictive capabilities of these theoretical models are largely unknown. The experimental investigation presented herein, is motivated by this observation and is directed towards partially filling this significant void in the literature. In order to accomplish this goal, a comprehensive experimental study was undertaken of a slider-crank mechanism in which the radial clearance at the gudgeon-pin bearing was carefully controlled. Response data at different operating speeds are presented, along with an investigation of the bearing characteristics from which the coefficient of restitution, which features in many of the proposed mathematical models, was evaluated. Finally, design guidelines are distilled from the experimental data to relate the response of the system to the response of a similar system without bearing clearance.
A Computer Aided Geometric Method for Development of Thick Surfaces
Authors: Gurunathan B. , Dhande S. G. 
Published: April 2021

Abstract
Uniformly thick surfaces are considered for development. A thick surface is considered to be a set of thin surfaces lying one over the other. A mean surface is defined. Other surfaces in the set are defined in terms of the mean surface as well as the distance between them and the mean surface. Once the mean surface is developable, other surfaces are shown to be developable. These surfaces are developed individually and then a co-ordinate transformation is applied to these developments to take into account the fact that the origin and axes of the development are different for different surfaces. This completes the geometrical development of the thick surface. Plastic deformations taking place during the manufacturing process are not taken into account here.
The Symmetric Rank One Formula and its Application in Discrete Nonlinear Optimization
Authors: Cha J. Z. , Mayne R. W. 
Published: April 2021

Abstract
The hereditary properties of the Symmetric Rank One (SRI) update formula for numerically accumulating second order derivative information are studied. The unique advantage of the SR1 formula is that it does not require specific search directions for development of the Hessian matrix. This is an attractive feature for optimization applications where arbitrary search directions may be necessary. This paper explores the use of the SR1 formula within a procedure based on recursive quadratic programming (RQP) for solving a class of mixed discrete constrained nonlinear programming (MDCNP) problems. Theoretical considerations are presented along with numerical examples which illustrate the procedure and the utility of SR1.
A Method for Comparative Performance Evaluation of Structural Optimization Codes: Part II — Applications
Authors: Subbarayan G. , Bartel D. L. , Taylor D. L. 
Published: April 2021

Abstract
This paper presents a systematic procedure for the comparative performance evaluation of nonlinear programming codes intended for applications in structural optimization. Part I discusses the issues in the evaluation of nonlinear programming codes and proposes a performance evaluation scheme for structural optimization codes. Aspects of performance evaluation such as the choice of test problems and appropriate set of performance criteria for structural optimization codes are described. A procedure to analyze codes based on their observed geometric behavior for test problems is also presented. The proposed method is contrasted with studies conducted in the past for comparative performance evaluation of nonlinear programming codes. Part II presents an application of the theory described in part I to evaluate two design optimization codes.
Optimization of Reinforced Concrete Footings Used to Support Wind Loaded Structures
Authors: Hannan M. R. , Johnson G. E. 
Published: April 2021

Abstract
The application of optimization to the design of structures where the ability to sustain a large wind load is considered. This investigation was an outgrowth of research intended to increase the capabilities of engineers who design such structures as highway signs and elevated steam lines. A second objective was to see if optimization techniques could successfully be applied to this class of problems.
The objective was to minimize the mass of the footing needed to support the structure. A model of a reinforced concrete footing which supports the structure is given. This model includes constraints which assure that the structure won’t overturn and that stresses in the footing and soil don’t exceed the strength of the respective materials. Optimization software (a conjugate gradient method) uses this model to find a design which minimizes the mass of the footing. Results for various loadings and configurations are presented. Analysis of the results indicate that for lightly loaded structures the optimal footing design tends to be a piling (large depth relative to length) while for a relatively heavily loaded structure the optimal design is more of a plate (large length relative to depth). A copy of the Fortran source code used to model the system and the optimization algorithm is available from either author.
Design for Latitude Using TOPT
Authors: d’Entremont K. L. , Ragsdell K. M. 
Published: April 2021

Abstract
An enhanced nonlinear programming code has been developed and applied to a turbogenerator hydrostatic thrust bearing design problem. The original code was OPT. It is augmented by a pre- and post-processor which addresses the performance variance minimization problems posed by Japan’s Genichi Taguchi. The new code TOPT is formed by adapting Taguchi’s external design influence and quality loss concepts to OPT. TOPT’s results are compared to an optimization using traditional Taguchi methods which are introduced to the reader. These two approaches yield comparable results.
A New Algorithm for Inverse Design of Flow Headers
Authors: Araya R. , Modi V. 
Published: April 2021

Abstract
Fluid distribution system design in telecommunication equipment, airconditioning installations, condensers, air driers, cold plates in computer cooling equipment and heat exchangers requires uniformity of flow distribution over the core face for efficient operation. An acceptable system geometry necessitates frequent turning of the flow. In this paper we consider the problem of designing an oblique flow header shape that produces the desired downstream flow.
A numerical algorithm to obtain the optimum header geometry for two-dimensional inviscid irrotational flow is proposed. The algorithm is based on computation of the first variation of the downstream flow due to system boundary variation. The calculation of such variation is easily implemented utilizing the same boundary element method procedure as that for the calculation of two-dimensional potential flow.
Dynamics of a Stepping Motor Driven Conventional Machine Slide
Authors: Umez-Eronini E. I. 
Published: April 2021

Abstract
A model of a conventional, manually driven machine tool slide which is retrofitted for Numerical Control by merely incorporating high-power stepping motor drives, is developed. This model includes the relatively large amount of stick-slip friction in the slideways, and backlash in the drive chain, which characterize the conventional slide. Simulation results obtained using this model highlight the peculiar dynamic behavior, at low speed positioning and contouring operations, of such large stepping motor drive systems under electronically damped open-loop control. The results also demonstrate the feasibility of this low-cost approach to the retrofitting problem, given adequate open- or closed-loop controllers, and provide useful insight into the design of such control systems.
Computer-Aided Design of a Diesel Engine Chassis Mount Using the Finite Element Method
Authors: Haghighi K. , Smith M. G. , Krutz G. W. , Bennett L. , Buchanan J. W. 
Published: April 2021

Abstract
A new diesel engine mounting bracket, that was used as a part of a repowering package for one ton trucks, was analyzed by using a finite element model under an equivalent static loading to simulate maximum service loads. Upon finding stresses above the yield strength of the material, alterations in the design were made to stiffen the bracket in the areas of high stresses, the maximum of which was at the isolator mounting hole. This new design added several dimples and bends to increase the stiffness of the entire bracket, especially in the isolator mounting area. The results of these design changes indicated a successful reduction of the stress in that critical area. The fatigue life was evaluated for the chassis mount, and was found to be acceptable for this retrofit condition.
Spline Functions Applied to the Synthesis and Analysis of Non-Rigid Cam-Follower Systems
Authors: Tsay D. M. , Huey C. O. 
Published: April 2021

Abstract
A general, systematic procedure for the synthesis and analysis of oams is presented. The method accounts for the non-rigid behavior of the follower system and can be readily implemented as a computer aided design tool. It employs spline functions to interpolate motion constraints in the synthesis of output motion programs. It applies the spline collocation method for the solution of the differential equations in determining the cam profile and in analyzing the follower system response. The development presented is based on a single degree-of-freedom (DOF) follower model. It offers the advantage over other methods of greater generality yet requires only routine application procedures. An example is provided to illustrate the complete synthesis/analysis procedure. The results from the example are compared to those obtained using a conventional polynomial approach.
Determining the Presence of Rigid Sub-Frames in Kinematic Chains
Authors: Bhasin R. , Beard J. E. , Brewer J. A. 
Published: April 2021

Abstract
Applying the concepts of the instant centers (IC’s) to the kinematic structure of a mechanism, a powerful new tool has been developed to detect the presence of a rigid sub-frame (RSF) in it’s configuration. The presence of an over-defined IC indicates the presence of an over-constrained sub-chain in the configuration. A ‘trace’ (T) of all the instant center, obtained at any stage of the analysis, is required to be maintained and compared, in order to develop a generalized method that applies only to the topology of the configuration. The compact, efficient and completely automated process of RSF checking allows a purely arbitrary approach to the creation of the kinematic structure of planar mechanisms of unlimited size.
Automatic Selection of Four-Bar Linkage Designs for Path Generation Task
Authors: Kota S. , Gudapati R. B. 
Published: April 2021

Abstract
Often a simple mechanism to trace a desired path is sought. Coupler curves of linkages are generally difficult to determine, especially in the case that a certain shape or a type of curve is required for a particular application. Precision point techniques do not guarantee that the desired path will be generated. The design methodology presented in this paper is an indirect synthesis approach to design four-bar linkages that trace (approximately) a given desired path. Simple and yet extremely useful design charts for the initial selection of four-bar linkage candidate designs are presented in this paper. This is based on our philosophy that an arbitrary path (desired) can be viewed as an approximation to a known symmetrical path. Four-bar linkages that generate symmetrical paths are easier to design and exhibit a definite pattern of changes in their shape as the linkage parameters are varied. The first step in automating the design-selection process requires a satisfactory means to quantitatively compare the desired with the known (symmetrical) coupler curves. This paper addresses various issues involved in the comparison of two arbitrary curves. Based on curve parametrization, an effective algorithm for quantitative shape evaluation of arbitrary curves is developed. Finally, the design charts and design examples are presented.
Robot Accuracy Qualification: A Stochastic Differential Kinematic Monte Carlo Error Combination Approach
Authors: Sturm A. J. , Lee M.-Y. 
Published: April 2021

Abstract
This paper presents a stochastic model and a Monte Carlo computer simulation algorithm to combine all measurable non-linear kinematic and misalignment error components to predict the overall tooltip quasi-static robot spatial position accuracy for a gantry robot. These errors include joint position accuracies, joint misalignments, joint zero position offsets, axis directional straightness, squareness errors and kinematic coupling errors. All of these errors can be independently measured using a laser interferometer and/or other precision measuring instruments. The interation between robot joints and coupling between these error components are very complex making the determination of the overall robot spatial position accuracy difficult. In this paper a Monte Carlo computer simulation program for predicting overall robot spatial position accuracy based on a stochastic error model was developed. Finally, simulation results are compared with direct spatial accuracy test results using a computerized Theodolite system. This robot spatial accuracy qualification methodology has been accepted and recommended by RIA as part of American National Standard for robot accuracy evaluation.
A First Class of Computational Tools for Preliminary Engineering Design
Authors: Wood K. L. , Antonsson E. K. 
Published: April 2021

Abstract
Preliminary engineering design intrinsically consists of imprecise descriptions of the input parameters. We present new conceptual and algorithmic procedures for dealing with such imprecise descriptions. Specifically, a two-part method is outlined for performing design calculations on these “fuzzy” parameters, as well as determining a measure for the parameters’ coupling. By interpreting the input set of variables for preliminary design in terms of fuzzy sets, we demonstrate how the engineer may associate his subjective meaning with the input parameters and the output functional requirement, leading to the foundation of our approach. An example of the method highlights the primary issues and the implementation scheme as a computational tool.
Respectful care an added extra: a grounded theory study exploring intrapartum experiences in Zambia and Tanzania
Authors: Lavender Tina , Bedwell Carol , Kasengele Chowa Tembo , Kimaro Debora , Kuzenza Flora , Lyangenda Kutemba , Mills Tracey A , Nsemwa Livuka , Shayo Happiness , Tuwele Khuzuet , Wakasiaka Sabina , Laisser Rose 
Published: April 2021

BackgroundQuality of maternal and newborn care is integral to positive clinical, social and psychological outcomes. Respectful care is an important component of this but is suboptimum in many low-income settings. A renewed energy among health professionals and academics is driving an international agenda to eradicate disrespectful health facility care around the globe. However, few studies have explored respectful care from different vantage points.MethodsWe used Strauss and Corbin’s grounded theory methodology to explore intrapartum experiences in Tanzania and Zambia. In-depth interviews were conducted with 98 participants (48 women, 18 partners, 21 health-providers and 11 key stakeholders), resulting in data saturation. Analysis involved constant comparison, comprising three stages of coding: open, axial and selective. The process involved application of memos, reflexivity and positionality.ResultsFindings demonstrated that direct and indirectsocial discriminationled to inequity of care. Health-providers were believed to displaymanipulative behavioursto orchestrate situations for their own or the woman’s benefit, and were oftencaring against the odds, in challenging environments. Emergent categories were related to the core category:respectful care, an added extra, which reflects the notion that women did not always expect or receive respectful care, and tolerated poor experiences to obtain services believed to benefit them or their babies. Respectful care was not seen as a component of good quality care, but a luxury that only some receive.ConclusionBoth quality of care and respectful care were valued but were not viewed as mutually inclusive. Good quality treatment (transactional care) was often juxtaposed with disrespectful care; with relational care having a lower status among women and healthcare providers. To readdress the balance, respectful care should be a predominant theme in training programmes, policies and audits. Women’s and health-provider voices are pivotal to the development of such interventions.