bluuebunny/crossref_metadata_2025 huggingface dataset:
Current practices in nutrition management and disease incidence of common marmosets (Callithrix jacchus)
Authors: Goodroe Anna , Wachtman Lynn , Benedict William , Allen‐Worthington Krystal , Bakker Jaco , Burns Monika , Diaz Leslie Lynn , Dick Edward , Dickerson Mary , Eliades Steven J. , Gonzalez Olga , Graf Dina‐Jo , Haroush Keren , Inoue Takashi , Izzi Jessica , Laudano Allison , Layne‐Colon Donna , Leblanc Mathias , Ludwig Brian , Mejia Andres , Miller Cory , Sarfaty Anna , Sosa Megan , Vallender Eric , Brown Celeste , Forney Larry , Schultz‐Darken Nancy , Colman Ricki , Power Michael , Capuano Saverio , Ross Corinna , Tardif Suzette
Published: April 2021

Background

A survey was developed to characterize disease incidence, common pathology lesions, environmental characteristics, and nutrition programs within captive research marmoset colonies.

Methods

Seventeen research facilities completed the electronic survey.

Results

Nutritional management programs varied amongst research institutions housing marmosets; eight primary base diets were reported. The most common clinical syndromes reported were gastrointestinal disease (i.e. inflammatory bowel disease like disease, chronic lymphocytic enteritis, chronic malabsorption, chronic diarrhea), metabolic bone disease or fracture, infectious diarrhea, and oral disease (tooth root abscesses, gingivitis, tooth root resorption). The five most common pathology morphologic diagnoses were colitis, nephropathy/nephritis, enteritis, chronic lymphoplasmacytic enteritis, and cholecystitis. Obesity was more common (average 20% of a reporting institution's population) than thin body condition (average 5%).

Conclusions

Through review of current practices, we aim to inspire development of evidence‐based practices to standardize husbandry and nutrition practices for marmoset research colonies.
CRRT prescription and delivery of dose
Authors: Neyra Javier A. , Tolwani Ashita
Published: April 2021

Continuous renal replacement therapy (CRRT) is the preferred modality of extracorporeal renal support for critically ill patients with acute kidney injury (AKI). The dose of CRRT is reported as effluent flow in ml/kg body weight per hour (ml/kg/h). Solid evidence supports that the delivered CRRT effluent dose for critically ill patients with AKI should be 20–25 ml/kg/h on average. To account for treatment interruptions and the natural decline in filter efficiency over time, it is recommended to prescribe 25–30 ml/kg/h of effluent dose. However, transient higher doses of CRRT in specific clinical scenarios may be needed to accommodate specific solute control needs of a particular patient at a given time. Consequently, there should be consideration of the potential adverse consequences of non‐selective clearance such as undesired antimicrobials and nutrients removal. In this manuscript, we provide a summary of evidence related to CRRT dose, practical aspects for its calculation at the time of prescribing CRRT, and considerations for addressing the expected gap between prescribed and delivered CRRT dose. We also provide a framework for monitoring and implementation of CRRT dose as a quality indicator of CRRT delivery.
Reason, Revelation, and Sceptical Argumentation in 12th‐ to 14th‐Century Byzantium
Authors: Greig Jonathan
Published: April 2021

In middle to late Byzantium, one finds dogmatic‐style sceptical arguments employed against human reason in relation to divine revelation, where revelation becomes the sole criterion of certain truth in contrast to reason. This argumentative strategy originates in early Christian authors, especially Clement of Alexandria (c. 150–215 CE) and Gregory Nazianzen (c. 329–390 CE), who maintain that revelation is the only domain of knowledge where certainty is possible. Given this, one finds two striking variations of this sceptical approach: a “mild” variant (represented by Clement), where knowledge derived from human reason admits partial access to truths manifested in revelation, if imperfect; and a “strict” variant (represented by Gregory), where knowledge derived from human reason does not admit any access to truths in revelation. This paper analyzes the three Byzantines, Nicholas of Methone (d. 1160/66 CE), Theodore Metochites (1270–1320 CE), and Gregory Palamas (1296–1357/59 CE), who each display certain tendencies toward these two “poles” in their respective epistemological positions on knowledge through reason and faith.
An international comparison of anti‐SARS‐COV‐2 assays used for seroprevalence surveys from blood component providers
Authors: Lewin Antoine , Drews Steven J. , Lieshout‐Krikke Ryanne , Erikstrup Christian , Saeed Sahar , Faddy Helen , Uzicanin Samra , Custer Brian , O’Brien Sheila F ,   the Surveillance, Risk Assessment, Policy, the Virology Sub‐groups of the ISBT Transfusion Transmitted Infectious Diseases Working Party
Published: April 2021

Background and objectives

Access to large pools of healthy adult donors advantageously positions blood component providers to undertake anti‐SARS‐CoV‐2 seroprevalence studies. While numerous seroprevalence reports have been published by blood operators during the COVID‐19 pandemic, details on the assay used has not been well documented. The objectives of this study were to evaluate the diversity of assays being used by blood operators and assess how this may affect seroprevalence estimates.

Materials and methods

We surveyed 49 blood component providers from 39 countries. Questionnaire included information on the number and identity of assays used, the detected immunoglobulin(s) and target antigen, and performance characteristics (sensitivity, specificity).

Results

Thirty‐eight of the 49 contacted blood suppliers provided at least partial responses. The results indicate that 19 commercial and five in‐house serology assays have been used by surveyed blood operators. The Abbott SARS‐CoV‐2 IgG assay was the most commonly used kit and utilized by 15 blood suppliers. Two assays did not detect IgG, but detected either IgM/IgA or IgM. 68·2% of assays targeted the spike protein and 50% the nucleocapsid protein, while 18·2% targeted both viral proteins. The sensitivity and specificity of IgG‐specific assays ranged from 71·9% to 100% and from 96·2% to 100%, respectively. As of 18 October 2020, the seroprevalence was below 5% in 10 of 14 countries reporting.

Conclusion

Our results highlight the diversity of assays being used. Analyses comparing blood donor seroprevalence across countries should consider assay characteristics with optimization of signal/cut‐off ratios and consistent methodology to adjust for waning antibody.
AXIN1 knockout does not alter AMPK/mTORC1 regulation and glucose metabolism in mouse skeletal muscle
Authors: Li Jingwen , Knudsen Jonas R. , Henriquez‐Olguin Carlos , Li Zhencheng , Birk Jesper B. , Persson Kaspar W. , Hellsten Ylva , Offergeld Anika , Jarassier William , Le Grand Fabien , Schjerling Peter , Wojtaszewski Jørgen F.P. , Jensen Thomas E.
Published: April 2021

Key points

Tamoxifen‐inducible skeletal muscle‐specific AXIN1 knockout (AXIN1 imKO) in mouse does not affect whole‐body energy substrate metabolism.

AXIN1 imKO does not affect AICAR or insulin‐stimulated glucose uptake in adult skeletal muscle.

AXIN1 imKO does not affect adult skeletal muscle AMPK or mTORC1 signalling during AICAR/insulin/amino acid incubation, contraction and exercise.

During exercise, α2/β2/γ3AMPK and AMP/ATP ratio show greater increases in AXIN1 imKO than wild‐type in gastrocnemius muscle.

AXIN1 is a scaffold protein known to interact with >20 proteins in signal transduction pathways regulating cellular development and function. Recently, AXIN1 was proposed to assemble a protein complex essential to catabolic‐anabolic transition by coordinating AMPK activation and inactivation of mTORC1 and to regulate glucose uptake‐stimulation by both AMPK and insulin. To investigate whether AXIN1 is permissive for adult skeletal muscle function, a phenotypic in vivo and ex vivo characterization of tamoxifen‐inducible skeletal muscle‐specific AXIN1 knockout (AXIN1 imKO) mice was conducted. AXIN1 imKO did not influence AMPK/mTORC1 signalling or glucose uptake stimulation at rest or in response to different exercise/contraction protocols, pharmacological AMPK activation, insulin or amino acids stimulation. The only genotypic difference observed was in exercising gastrocnemius muscle, where AXIN1 imKO displayed elevated α2/β2/γ3 AMPK activity and AMP/ATP ratio compared to wild‐type mice. Our work shows that AXIN1 imKO generally does not affect skeletal muscle AMPK/mTORC1 signalling and glucose metabolism, probably due to functional redundancy of its homologue AXIN2.
A quantitative description of macaque ganglion cell responses to natural scenes: the interplay of time and space
Authors: Schottdorf Manuel , Lee Barry B.
Published: April 2021

Key points

Responses to natural scenes are the business of the retina. We find primate ganglion cell responses to such scenes consistent with those to simpler stimuli. A biophysical model confirmed this and predicted ganglion cell responses with close to retinal reliability.

Primate ganglion cell responses to natural scenes were driven by temporal variations in colour and luminance over the receptive field centre caused by eye movements, and little influenced by interaction of centre and surround with structure in the scene.

We discuss implications in the context of efficient coding of the visual environment. Much information in a higher spatiotemporal frequency band is concentrated in the magnocellular pathway.

Responses of visual neurons to natural scenes provide a link between classical descriptions of receptive field structure and visual perception of the natural environment. A natural scene video with a movement pattern resembling that of primate eye movements was used to evoke responses from macaque ganglion cells. Cell responses were well described through known properties of cell receptive fields. Different analyses converge to show that responses primarily derive from the temporal pattern of stimulation derived from eye movements, rather than spatial receptive field structure beyond centre size and position. This was confirmed using a model that predicted ganglion cell responses close to retinal reliability, with only a small contribution of the surround relative to the centre. We also found that the spatiotemporal spectrum of the stimulus is modified in ganglion cell responses, and this can reduce redundancy in the retinal signal. This is more pronounced in the magnocellular pathway, which is much better suited to transmit the detailed structure of natural scenes than the parvocellular pathway. Whitening is less important for chromatic channels. Taken together, this shows how a complex interplay across space, time and spectral content sculpts ganglion cell responses.
El símbolo como elemento unificador entre la teología y la poesía
Authors: Meléndez Guerrero Luis Gustavo
Published: April 2021

Con este artículo esperamos establecer la relación entre teología y poesía basada en el poder de lo simbólico. Para abordar tal objetivo debemos considerar la siguiente pregunta: ¿De qué manera se puede alojar lo trascendente en lo inmanente? Creemos que es el carácter simbólico de la poesía lo que nos permite hablar de esta presencia de lo trascendente en lo inmanente. Para Paul Tillich, los símbolos se dirigen por encima de sí mismos hacia algo más. Los símbolos, a diferencia de los signos, participan en el poder de lo que simbolizan. Los símbolos religiosos pueden ser símbolos verdaderos solo si participan en el poder de lo divino al que apuntan. La revelación manifiesta nuestra preocupación última. En este sentido, la revelación de Jesús como el Cristo, en el que se arraiga el mensaje cristiano, es la revelación final y real, que a su vez resuelve la finitud de nuestra razón existencial. La importancia de los símbolos religiosos radica así en su “doble filo”: apuntan a lo infinito, así como a lo finito; conducen lo infinito hacia lo finito y lo finito hacia lo infinito; revelan la vida divina para lo humano y lo humano para lo divino. Así entendido, el carácter simbólico será el vínculo que mueve el lenguaje poético hacia el lenguaje teológico cuando la tarea simbólica es, necesariamente, la que nos impulsa hacia un horizonte abierto, hacia el misterio que nos trasciende y al mismo tiempo que nos centra. A este fin, consultaremos con dos autores cuyo pensamiento orientará nuestra reflexión: desde un punto de vista teológico, Paul Tillich será nuestro principal punto de referencia; desde la dimensión poética, los escritos de Octavio Paz guiarán nuestra investigación. Mi hipótesis propone ver en la poesía un carácter mistagógico. Este concepto proporciona las bases para un diálogo entre la teología cristiana de la revelación (Tillich) y la idea de la “revelación poética” (como defiende Paz).
An Estimate of the Bound of the Lyapunov Exponents for Caputo–Hadamard Fractional Differential System
Authors: Li Changpin , Yin Chuntao
Published: April 2021

This paper is devoted to estimating the bound of the Lyapunov exponents for the Caputo–Hadamard fractional differential system. First, using the Gronwall inequality, we analyze the continuous dependence of the solution to the Caputo–Hadamard fractional initial value problem (IVP). Then, we define the Lyapunov exponents for the Caputo–Hadamard fractional differential system and estimate their bounds. Besides, numerical examples are displayed which support the theoretical results.
NWRAG, a New Algorithm for Structural Optimization
Authors: No M. , Aguinagalde J. M.
Published: April 2021

This paper presents an algorithm to solve the optimum design problem for general structures. The algorithm is based on the solution of the nonlinear system of equations derived from the Kuhn-Tucker optimality conditions. Sets of active design variables and active behaviour constraints are used. Some practical examples are presented to show how NWRAG performs better than other optimality criterion based algorithms for structures involving bending effects.
Position and Motion Planning in a Confined Region via Nonlinear Programming
Authors: Mayne R. W.
Published: April 2021

This paper describes the formulation of a position and motion planning problem in an optimization setting. Emphasis is placed on planning movements in a confined workspace where contacts must be avoided. The formulation includes the possibility of extra degrees of freedom and is demonstrated in detail on a simple robot problem. Robot positioning and trajectory planning are considered within a two dimensional workspace and a recursive quadratic programming procedure is used for the optimization. The results presented herein show satisfactory performance and considerable promise for extension to more complex configurations and three dimensions.
Optimal Valve Lift Curve Design for Valve Train Cam Systems
Authors: Chan C. , Pisano A. P.
Published: April 2021

The design of valve lift curves for valve train cam systems is formulated as an optimization problem, in which the maximum principle is applied. The solution is obtained by utilizing the maximum principle approach for an equivalent linear quadratic optimal control problem. The outcome of the design shows trade-offs between several design criteria. The method is applied to the specification of the lift curve for a finger-follower cam system, and design charts are developed for different choices of design parameters. The method presented in this study provides a unified way of valve lift curve design for those cam systems where the objective functions can be clearly defined.
Analysis and Optimal Design of Spatial Mechanical Systems
Authors: Ashrafeiuon H. , Mani N. K.
Published: April 2021

This paper presents a new approach to optimal design of large multibody spatial mechanical systems. This approach uses symbolic computing to generate the necessary equations for dynamic analysis and design sensitivity analysis. Identification of system topology is carried out using graph theory. The equations of motion are formulated in terms of relative joint coordinates through the use of velocity transformation matrix. Design sensitivity analysis is carried out using the Direct Differentiation method applied to the relative joint coordinate formulation for spatial systems. Symbolic manipulation programs are used to develop subroutines which provide information for dynamic and design sensitivity analysis. These subroutines are linked to a general purpose computer program which performs dynamic analysis, design sensitivity analysis, and optimization. An example is presented to demonstrate the efficiency of the approach.
Supercomputer-Based Sensitivity Analysis of Constrained Dynamic Systems
Authors: Krishnaswami P. , Ramaswamy S.
Published: April 2021

Generalized design sensitivity analysis of constrained dynamic systems is a computationally intensive process that is well-suited for implementation on a modern supercomputer. A matrix oriented method for design sensitivity analysis, based on direct differentiation, is developed. An algorithm based on this development was implemented in a computer code which was then run on a Cray X-MP supercomputer. The implementation attempts to make full use of the vectorization capabilities of this machine. The numerical examples that were run on this implementation were compared with results presented in the literature in order to verify the program and to assess its computational performance.

The results show that the use of supercomputers for performing design sensitivity analysis of dynamic systems using this method produces a dramatic reduction in the computing time; it is anticipated that this will make the optimization of very large-scale dynamic systems computationally viable.
Goal Programming Approach for the Balancing of Variable Input Speed Mechanisms
Authors: Kaplan R. L. , Rao S. S.
Published: April 2021

The minimization of the dynamic reactions of high speed, variable input speed planar mechanisms is considered using multiobjective nonlinear programming techniques. A general procedure, which can easily incorporate variable angular velocity input, joint friction and external loading, is used for the dynamic analysis of the mechanisms. A goal programming approach is outlined for the solution of the optimization problem. This procedure is coupled with an exterior penalty function approach in developing the necessary computer program. An example four-bar linkage is considered for illustration. It is observed that the approach presented in this paper offers greater flexibility and wider application in the optimal balancing of high speed linkages.
Optimization of the Control Function for a Footless Biped in a Stationary, Upright Posture
Authors: Hsu M. S. , De Spain M. , Shaw J. , Mulder M. , Wagner N.
Published: April 2021

The stability of a footless biped in a stationary, upright posture is studied on the sagittal plane using two and three link models. Closed form expression of the stability range for the control gains is derived from Routh-Hurwitz criteria. Evaluation and optimization of the multiple gain systems are realized using statistical and numerical techniques. The optimal control gains are obtained and the gain-locus is derived. The algorithm for optimizing the control function is provided and several numerically derived examples are illustrated.
Engineering of Flexible Software for Real-Time Systems
Authors: Schmuter S. L. , Hamidieh Y. A.
Published: April 2021

Flexibility of software for real-time control of machinery becomes one of the major objectives in view of ever increasing software costs. Such flexibility promotes efficiency in the development stage, but even more so, it enhances maintainability and facilitates upgrade during retooling and job changeover. A multilevel organization of software is described whereby the computational units in a particular level perform a special class of tasks and have specific privileges assigned to that level. A slot-matrix frame of the top control level along with a knowledge base provides for flexible chaining of various functions from the levels below, thus allowing substantial new features to be incorporated into the system if and when required. At the interactive level, selection alternatives for the operator are intelligently inferred and displayed through a rule base, and inputs are interpreted. The entire software is embedded in a number of processes for off-line computations, real-time control, transformations and data transfer. An example for robotic applications is elaborated.
Fault Tree Approach for the Reliability Analysis of Gear Trains: Part II — Example Applications
Authors: Pan T. S. , Rao S. S.
Published: April 2021

The application of fault tree techniques to the analysis of gear trains is considered. The techniques involve the decomposition of the system into a logic diagram or fault tree in which certain basic or primary events lead to a specified top event which signifies the total failure of the system. The fault trees are used to obtain minimal cut sets from which the modes of system failure and hence the reliability measure for the top event can be calculated. The method of constructing fault trees and the subsequent estimation of reliability of the system is illustrated through a nine speed compound gear train and a five speed epicyclic gear train.
Some Design Considerations for Computer Controlled Inspection (CCI) Systems in Statistical Process Control (SPC) Applications
Authors: Shaikh R. A.
Published: April 2021

US manufacturers are under siege from the extreme foreign competition. So it is little wonder that domestic producers are renewing their commitment to quality. And the key to higher quality is automation. Consistency and accuracy generally improves when automated machines producing parts remain in proper order. An automated system producing off specs. parts will do so with the same consistency it produces correct output, this time not only it produces scrap, but produces it faster. Therefore, automated inspections and Computer Aided Quality Engineering (CAQE), that integrates with all the other factory automation manufacturing functions seem to be the most viable solution to meet the quality challenge.

This paper outlines the importance of SPC in the automation environments, and describes some design concepts for the development and implementation of CCI systems. Typical design applications and future trends are discussed. The paper concludes with suggestions for effective implementation of CCI systems.
Two Generalizations of the Isometric Projection in Geometric Design
Authors: Wilde D. J.
Published: April 2021

The well-known pictorial drafting technique of isometric drawing is here generalized in two ways, called “isoclinal” and “axial”, or collectively, “symmetric”. Although the isoclinal projection preserves the useful property of foreshortening adjacent edges equally, and the axial projection foreshortens adjacent edges equally, the directions for these projections usually differ from that for isometric projection. Formulas are derived for the isoclinal and axial directions and their foreshortening factors and rotation matrices. Although intended for three-dimensional computer-aided design, the symmetric projections can also be performed on a drawing board with a protractor. Graphic examples involving design of non-rectangular connectors for three skew structural members and adjacent plates in space are presented.
Computer Graphics and Analysis in Elastomeric Compact Seal Design
Authors: Johannesson H. L.
Published: April 2021

The use of advanced calculations are necessary in elastomeric seal design if the today situation of “trial and error” shall be avoided. In order to make it easy for the designer to carry out these calculations, computer graphics can be used together with calculation programs.

In this work it is shown how a general purpose turn-key CAD-system can be used together with complex calculation programs in elastomeric compact seal design. It is demonstrated how communication between the CAD-system and the calculation program can be established with the use of the “graphic application programming language” that must be available within the CAD-system.

The suggested computer aided design procedure is especially suitable for products like seals, which have simple geometry but require complicated calculations.
Integration of Expert System Into a CAD System of Springs
Authors: Jin Yu , Shihua Liu , Jing Qin , Ji Zhou
Published: April 2021

By combining the reasoning design of the expert system with the analysis and calculation of spring based on a mathematical model and its optimal design, an intelligent spring CAD system has been established. The expert system technique is adopted for such non-calculating designing steps as the selection of scheme, the determination of parameters as well as for the development of the technological process, thus greatly strengthening the original CAD system of springs. This paper provides a detailed description of the function, structure, characteristic features and significance of the said system.
Reliability Analysis of Robot Manipulators
Authors: Bhatti P. K. , Rao S. S.
Published: April 2021

A probabilistic approach to robot kinematics is presented and the concept of manipulator reliability is introduced to obtain a better evaluation of the performance of manipulators. Techniques are presented to compute this reliability and its relationship to the geometric parameters such as tolerances and arm configuration are discussed. The aspects of accuracy and repeatability of manipulators are explained in terms of manipulator reliability. The reliability of a two-link planar manipulator and the Stanford arm are considered for numerical illustration.
Some Properties of a New Kinematic Structure for Robot Manipulators
Authors: Stoughton R. , Kokkinis T.
Published: April 2021

A 3 DOF closed chain kinematic structure particularly well suited to robot manipulators is explored. The structure has a number of distinct geometries, two of which are analyzed to reveal the geometric and Jacobian relationships, singularities and the workspace volume. These relationships are found to be much simpler than for other parallel actuated spatial structures with 3 or more DOFs. The geometries studied can have large workspace volumes. An optimization procedure is applied to select link lengths for which the Jacobian is relatively homogeneous. Singularities can be restricted to the boundary of the workspace. The proposed geometries can achieve speeds and accuracies unattainable with similar serial link designs.
On the Equations of Motion for Robot Arms and Open Kinematic Chains
Authors: Gupta S. , Townsend M. A.
Published: April 2021

The closed-form equations of motion for robot arms and other open kinematic chains are derived using the Newton-Euler equations in a form particularly suitable for the automatic modeling and on-line control of such mechanisms. The approach is based on Vukobratovic’s method (3), using more conventional Western notation.
Automated Modeling and Rapid Solution of Robot Dynamics Using the Symbolic Polynomial Technique
Authors: Townsend M. A. , Gupta S.
Published: April 2021

Fast and accurate solutions of the dynamic equations of a robot arm are required for real time on-line control. In this paper we present a new method for rapidly evaluating the exact dynamic state of a robot. This method uses a combination of symbolic and numerical computations on the equations of motion, which are developed in the form of polynomials — hence the name, the symbolic polynomial technique.
Dynamic Modeling of a Multi-Legged Robotic Vehicle: Part 1 — Kinematic Analysis
Authors: Hart R. A. , Ebrahimi N. D.
Published: April 2021

This two-part paper presents a dynamic model of a legged vehicle for travel on a variable-topographic terrain. In Part 1 of the paper, we develop expressions for the kinematics of the vehicular system. These expressions, in turn, form the foundation for the dynamic analysis of the robotic vehicle presented in Part 2 of the paper. The model applies to a system composed of a cargocarrying body supported by four multi-degree-of-freedom linkage assemblies whose configurations are adjustable to accommodate terrain irregularities. The mobility of the locomotion system is provided by four rigid wheels which serve as a base to the kinematic chains that extend from the platform of the vehicle. To assure dynamic equilibrium of all members in the system, torque actuators are employed at the joints between inter-connecting bodies to facilitate the adjustment of each articulated chain configuration without reducing the adaptability of the vehicle to ground profile variations. The dynamic model used for determining the system response to environmental contact forces is based on a Newton-Euler recursive formulation.
The Design of Three Jointed Two-Degree-of-Freedom Robot Fingers
Authors: Leaver S. O. , McCarthy J. M.
Published: April 2021

The design of modern mechanical hands requires a choice for the kinematic structure of the finger. The typical finger is a planar manipulator with one, two, or three independently controllable joints. Each controllable joint requires a motor and sensor system which increases the weight of the hand. There is a desire to minimize the number of degrees of freedom in a mechanical hand because the payload capacity of a manipulator is limited. Two degrees of freedom provides the required positioning capability of a finger tip (though not the ability to control contact angle). Three joints are required to provide the ability to enclose grasped objects. This paper considers the design of fingers which are planar manipulators with three joints but only two degrees of freedom. In addition to the fully coupled design, twelve classes of finger designs with varying degrees of de-coupling are presented. It happens that one of these classes includes the human finger, a mechanical model of which is presented in detail.
An Orthogonal-Decomposition Algorithm for Constrained Least-Square Optimization
Authors: Angeles J. , Anderson K. , Gosselin C.
Published: April 2021

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.