bluuebunny/crossref_metadata_2025 huggingface dataset:
CX3CR1 might be a promising predictor of systemic lupus erythematosus patients with pulmonary fibrosis
Authors: Qiu Fen , Li Youling , Zhu Yunhe , Li Gang , Lei Feifei , Zhang Shuang , Luo Lei , Zhu Jietao , Guo Yang , Du Boyu , Xi Xueyan
Published: March 2021

The inflammatory process in systemic lupus erythematosus (SLE) affects many organs including the lungs. Chemokines are suggested to play important roles in the pathogenesis of SLE with pulmonary fibrosis (PF). In the present study, our objective is to evaluate the correlation between chemokines and PF in SLE patients. Transcriptome sequencing analysis was used to find the different expressed genes between SLE patients with PF and without PF. Enzyme‐linked immunosorbent assay (ELISA) was used to detect serum levels of chemokines in SLE patients and healthy controls. Expression of CX3CR1 was measured by real‐time polymerase chain reaction (PCR) and flow cytometer. Sixteen differentially chemokine genes were found to be associated to SLE with PF. Meanwhile, the upregulation of C‐X3‐C motif chemokine receptor 1 (CX3CR1) and its ligand, CX3C chemokine ligand 1 (CX3CL1) were observed in SLE patients with PF than that of SLE patients without PF and healthy control. Phenotypic analysis also showed that the surface expression of CX3CR1 increased in PBMCs from SLE patients with PF. Our observations indicated that CX3CL1/CX3CR1 axis is associated with PF in SLE. CX3CR1 might be a promising predictor of SLE with PF and the interactions between CX3CL1 and CX3CR1 might provide potential candidate target for the treatment of SLE with PF.
Validation of an apoptosis assay for extracorporeal photopheresis
Authors: Hähnel Viola , Dormann Frauke , Kronenberg Katharina , Hutchinson James A. , Burkhardt Ralph , Ahrens Norbert
Published: March 2021

Objectives

This validation study investigated a flow cytometric apoptosis assay according to good manufacturing practice (GMP).

Background

Extracorporeal photopheresis (ECP) is a treatment for various immunological diseases and cutaneous T‐cell lymphomas. It is based on the induction of apoptosis by 8‐methoxypsoralene and ultraviolet A light. The quantification of apoptosis is therefore essential for ECP improvements. However, despite numerous publications on apoptosis, validated technical details are lacking.

Methods and materials

Mononuclear cells were collected by apheresis and treated by ECP or camptothecin. Samples taken before and after ECP were cultured for 24, 48 and 72 h and analysed for apoptosis and viability of T cells and monocytes by flow cytometry with Annexin V and 7‐AAD staining. Accuracy of the assay, intra‐ and inter‐assay precision and the pre‐analytical and analytical stability of the analytes were the investigated parameters.

Results

Our data indicate that the median intra‐ and inter‐assay precision coefficient of variation for T cells was 3.86% and 4.80%, respectively. Pre‐analytical stability of T cells and monocytes was ensured during short‐term storage for up to 2 h on ice. After staining, analytical stability was limited to 30 min, likely because of ongoing apoptosis and loss of monocytes due to plastic adhesion.

Conclusion

The results of this validation study show that the assay is GMP‐compliant and that its reliability, accuracy and precision are acceptable. While pre‐analytical stability of the cells was compatible with on‐site procedures, our analytical stability data indicate that this assay is not suited for batch mode analysis of ECP products.
Evaluation of scar revision after inadequate primary excision of cutaneous mast cell tumors in 85 dogs (2000–2013)
Authors: Karbe Georga T. , Davis Elizabeth , Runge Jeffrey J. , Brown Dorothy C. , Holt David E.
Published: March 2021

Objective

To determine the frequency of residual tumor, and factors associated with local recurrence and disease progression in dogs with incompletely excised mast cell tumors (MCT) following scar revision surgery.

Study Design

Retrospective study.

Animals

Eighty‐five dogs.

Methods

Medical records from January 2000 to April 2013 were reviewed. Dogs with scar revision surgery after incomplete primary MCT excision were included. Recorded were signalment; initial tumor size, location and grade; time interval between primary excision and scar revision surgery; presence of MCT in the resected scar; local recurrence, lymph node metastasis, systemic metastasis, and cause of death.

Results

Eighty six tumors in 85 dogs were studied. Residual MCT was found in 23 (27%) resected scars. Seven (8%) scars with residual MCT had incomplete or narrow margins. Follow‐up was available for 68 dogs (69 tumors; median 403 days; range 4–2939). Local recurrence was reported in three (4%) dogs at 212, 555, and 993 days. Disease progressed in 10 dogs (14.5%) with regional or systemic metastasis at a median of 207 days (64–1583). Margin status and presence of MCT in the resected scar were not associated with local recurrence or disease progression. Lymph node metastasis (p= .004), locoregional recurrence (p= .013), and disease progression (p= .001) were significantly more likely in Grade III tumors.

Conclusion

Twenty‐seven percent of resected scars contained residual MCT, but recurrence was uncommon after surgical revision.

Clinical significance

Clinicians should primarily consider tumor grade when estimating the likelihood of local recurrence and disease progression and determining the need for ancillary treatment of MCT after scar resection.
Necesidades de información de los padres para su participación en el proceso de parto
Authors: Arenas Cárdenasa Yury Marcela
Published: March 2021

Introducción: la participación del padre en el trabajo de parto le abarca una serie de decisiones para actuar libremente según su experiencia durante el nacimiento. Así, la presencia y preparación de los padres durante el evento se hace necesaria para el bienestar de la diada; por tal motivo, la investigación tiene el objetivo de ampliar conceptualmente las necesidades de información que requieren los padres para su participación en el proceso de parto. Materiales y Métodos: estudio cualitativo descriptivo interpretativo bajo la técnica de análisis de contenido dirigido. Se realizaron entrevistas de profundidad a 30 participantes. En el proceso de análisis, codificación y categorización de la información realizaron con apoyo de Atlas Ti. Versión 6.2. Resultados y Conclusiones: los resultados ampliaron conceptualmente las necesidades de información de los padres, los cuales se describieron y agruparon en tres categorías establecidas previamente por la literatura: Información como necesidad de acompañamiento, información como necesidad de expresar sentimientos, entrenador “entrenado” para el parto. Los padres manifiestan varios sentimientos que generalmente se intensifican con el progreso del trabajo de parto, este estudio evidencia que entre ellos la incertidumbre y el temor, son eventualmente ocasionados por la falta de información y el desconocimiento. El significado a la información se relaciona directamente con el papel que pueden desempeñar dentro de la sala de parto, la cual les permite interpretar y comprender el proceso que atraviesa la mujer, por consiguiente, desenvolverse con confianza mientras se da el nacimiento.
Cláusulas abusivas entre empresas. Evolución en los principales sistemas de derecho comparado
Authors: Morales Ortiz María Elisa , Mendoza Alonzo Pamela Andrea , Munita Marambio Renzo Esteban
Published: March 2021

Este artículo analiza la evolución que, en los tres principales sistemas de derecho comparado ha experimentado el control de contenido de cláusulas abusivas entre empresarios. Los sistemas que se comparan son el inglés, alemán y francés, buscando establecer, si es que existe, una tendencia o si en cambio se verifican diferentes modelos. Finalmente se concluye que, a través de diferentes técnicas legislativas, el control de cláusulas abusivas se extiende más allá de la relación de consumo a contratos entre empresarios, pero con una regulación distinta de la aplicable a los contratos de consumo.
Design Information System Infrastructure to Support Collaborative Design in a Large Organization
Authors: Bliznakov Plamen I. , Shah Jami J. , Jeon Dae K. , Urban Susan D.
Published: March 2021

In collaborative design in large organizations, many design tasks are executed concurrently by different groups or departments. Many of these tasks influence each other. Collaborative design can be facilitated by an information system that allows each group to post the status of their respective tasks so that other groups can follow their progress, obtain parameters/specifications required in their own tasks, and avoid conflicts/incompatible solutions. This paper examines the functional requirements for such a Design Information System (DIS), considers alternative solutions, and describes an implementation of such a system. The proposed solution includes a hybrid model for the representation of design information at several levels of formalization and granularity. Both Product Data and Design Procedures (processes) are supported through some common pre-defined design elements (primitives), but the system can be extended to include new user-defined elements. The user interface implementation utilizes the World Wide Web and public domain browsers. The system is currently undergoing field testing in an on-going collaborative design project.
A Generic Framework for the Integration of Mechanical and Electrical CAD Tools for Concurrent Design of Consumer Electronic Products
Authors: Wang Fu-Chung , Wright Paul K. , Richards Brian C.
Published: March 2021

Most consumer or commercial electronic products are electromechanical systems consisting of mechanical components such as structures, enclosures, driving systems and mechanisms, combined with electrical components such as printed circuit boards (PCBs), power supply, wires (harness) and switches. The design of such multidisciplinary products involves high coordination and cooperation between the two different engineering fields of mechanical and electrical design. However, in spite of the advancements of CAD tool development in design automation technology within each field, a gap still exists for good communication between the designers in these two fields during the course of the design. This gap makes the design process of such products time-consuming and error prone. This paper describes a research effort that facilitates multidisciplinary concurrent design for consumer electronic products. The focus is on how to integrate mechanical and electrical CAD tools into a more flexible and extensible concurrent design environment to share and communicate critical design information during the design process. A multidisciplinary concurrent design environment based on the CAD framework concept is described. Approaches for integrating the design data and information in such a multidisciplinary design environment are discussed. A prototyping system for the concurrent design of consumer electronic products is also presented.
Optimal Tangent-Plane and Curvature Continuous Modification of Curves at a Common Nodepoint
Authors: Ye Xiuzi , Nowacki Horst
Published: March 2021

Curvature continuity of curves at nodepoints is required in modeling tangent-plane and curvature continuous n-sided surfaces and surfaces over arbitrary curve meshes. This paper provides methods for optimal modification of curves at a common nodepoint, to make them tangent-plane and curvature continuous at the nodepoint. These methods can also be used to optimally estimate the intrinsic measures such as the Gaussian and mean curvatures of surfaces with discrete line and curve mesh representations such as triangular meshes.
Implicit Function Alteration via Radius Mapping and Direct Function Modification
Authors: Ensz Mark T. , Ganter Mark A. , Storti Duane W.
Published: March 2021

In this paper, we present two closely related techniques, radius mapping, and direct function modification, that allow for the alteration of both the major geometry and surface features of implicit solids. The first technique, radius mapping, is applied to implicit functions generated by swept solid techniques. A more generalized technique, direct function modification, allows for the mapping of generalized function modifiers onto any implicit solid. Both the radius functions and the function modifiers can be either algebraic or non-algebraic in nature. Techniques for generating both algebraic and non-algebraic radius functions and function modifiers are given along with several examples of their use on both swept solids and implicit functions.
A New Approach to Intelligent Design
Authors: Xiao Renbin , Zhou Ji , Yu Jun , Cha Jianzhong
Published: March 2021

This paper analyses the cognitive aspect of intelligent design and points out that the nested structure of a human being’s cognition on a complex design object, which is generated by thinking iteration while design thinking being in the chaotic state is the fundamental mechanism of intelligent design. A taxonomy of design problems is given based upon fractal theory and a complex design problem is considered as a fractal in our approach. Some new concepts such as granularity, refinement and coarsening are defined. Based upon the concepts of a cluster of problems and designs, the nested design, a new model for intelligent design, is proposed as continuity of the above work. The main steps of the nested design are listed and an illustrated example is given to demonstrate its implementation. The characteristics of the nested design show that it is the design methodology oriented to complex design problems.
Experience As Constraints in Embodiment Design
Authors: Yao Zhihui , Murdoch Tim , Johnson Aylmer
Published: March 2021

A functional modelling system has been developed in the Cambridge EDC to support embodiment design. The system utilises constraint-based methods to represent design knowledge and to search for feasible solutions within given configurations. A recent extension of this research has enhanced the search processes by clustering the constraints according to a hierarchical structure. This has enabled new investigations into the capture and use of empirical constraints during embodiment design.

Quality is an important form of empirical design knowledge and may be evaluated in terms of technical merit, a property developed within the EDC from theories of configuration optimisation. Defined in terms of performance, reliability and economy, technical merit is a measure of the proximity of a technical system to the limitations of current technology. It is a premise of this paper that technical merit may be used to represent the estimate of design quality as a constraint early in the embodiment design stage.

The design process should benefit from this work in two ways: firstly potential design failures can be identified early; and secondly, the evaluation of alternative configurations will be more robust. As the result of quick and robust evaluation during the embodiment stage, overall design time may be reduced and design quality increased. The design of a gear train configuration is used to illustrate the method.
Geometric Modeling of a Moving Object With Self-Intersection
Authors: Hu Zeng-Jia , Ling Zhi-Kui
Published: March 2021

The solution to the self-intersection of a swept volume is the bottleneck to the geometric modeling of a moving object. Self-intersection of a swept volume is the result of an object, which is called a generator here, moving into a space which it previously occupied. A graphical solution is devised in this study. It consists of following steps. First of all, a candidate swept volume is created by warping a series of characteristics curves on the boundary of the generator in a given time domain. The result is the facet model of a swept volume. Secondly, a series of sectioning operations to the candidate swept volume are performed where the sectioning planes are parallel. If self-intersection exists for a given candidate swept volume, some of the resulting polygons (cross-sections) after the sectioning operations are complex polygons. Thirdly, an algorithm is proposed here to convert these polygons into sweep contours, which are simple polygons. A well defined facet model of the swept volume is then obtained by fitting the corresponding sweep contours with a surface.
Exploratory Investigation of Layered Fabrication Applied to Construction Automation
Authors: Pegna Joseph
Published: March 2021

After more than a decade of research in construction automation, robotic tools have brought little if any productivity improvement to the industry. In this paper, we argue that automation which applies to most manufacturing industry does not translate effectively to construction which is limited not by labor, but by process.

We propose a radical departure from generally accepted concepts in construction automation and demonstrate that new techniques of layered manufacturing can be applied effectively to construction. In the process, we also modified material processing of cement to adapt it to the requirements of rapid prototyping.

We illustrate our purpose with sample structures manufactured by incremental deposition of reactive bulk materials (cement and Silica in this instance).
Methods of System Identification for Anisotropic Laminates
Authors: Cinquini Carlo , Mariani Claudia , Venini Paolo
Published: March 2021

The present paper is concerned with the identification of thin anisotropic laminates under transverse dynamic loads. A variational formulation of the problem governing the out-of-plane vibrations of the system is outlined allowing application of the Rayleigh-Ritz methodology for the spatial discretization. The resulting vector differential equation is then solved in the time domain with the objective of collecting enough input/output pairs so as to permit the selected identification algorithm to converge. A few identification methods of parametric type are described and applied to clamped anisotropic laminates under the assumption of a SISO (single-input single-output) structure model. The choice of the latter, of the relevant parameters and of the excitation capable of producing significant dynamics are among the keys for the success of the procedure. Extensions to other categories of identification methods as well as applications for the active control of the laminate are currently under development.
Slicing: A Procedure for Tolerance Evaluation of Manufactured Parts Using CMM Measurement Data
Authors: Wang Yu , Gupta Shilendra , Rao Srinavas
Published: March 2021

This paper presents a sampling and processing procedure for tolerance evaluation of machined parts. In this method, deviations of the measured points from their ideal feature surface are evaluated in the plane where the data is measured by a Coordinate Measuring Machine (CMM). This procedure is called slicing. It is shown that the use of the structure inherent in measurement data has a potential in reducing computational complexity for evaluation of certain types of form tolerances without significant loss of accuracy. An application of the proposed method to the development of manufactured part model for automotive spaceframe structures is also discussed.
An Improved Simulated Annealing Algorithm for Optimal Design
Authors: Aly Sherif , Ogot Madara M. , Pelz Richard
Published: March 2021

A new algorithm based on the simulated annealing (SA) optimization algorithm is presented. This approach, simulated annealing with random search iterative improvement (SAWI), essentially initiates the SA process to locate the neighborhood of the global optimum. Prior to the convergence of SA, the algorithm switches to random search iterative improvement, a local search method, to converge to the optimum. The key to the effectiveness of SAWI is identifying when the premature termination of SA should occur. This paper presents the results of a parametric study conducted on the transition parameter, illustrating the effects of delayed and premature transition to the local search method, on the final solution. Two examples are presented and discussed to illustrate the efficacy of the algorithm. The results of these examples demonstrate that SAWI makes significant reductions in computation time while maintaining the simplicity of the original SA algorithm and without loss in quality of solution.
Guidelines for Reporting Engineering Optimization Results
Authors: Beltracchi Todd J.
Published: March 2021

This paper describes a set of guidelines for reporting engineering optimization testing results. These guidelines are intended to provide bias independent information for publication of testing results. These guidelines have been developed through conversations with a wide range of optimization software developers and users.
Optimization Methods for Calculating Design Imprecision
Authors: Law William S. , Antonsson Erik K.
Published: March 2021

The preliminary design process is characterized by imprecision: the vagueness of an incomplete design description. The Method of Imprecision uses the mathematics of fuzzy sets to explicitly represent and manipulate imprecise preliminary design information, enabling the designer to explore the space of alternative designs in the context of the designer and customer’s preferences among alternatives. This paper introduces new methods to perform Method of Imprecision calculations for general non-monotonic design evaluation functions that address the practical necessity to minimize the number of function evaluations. These methods utilize optimization and experiment design.
Mixed Variable Optimization Using Taguchi’s Orthogonal Arrays
Authors: Chi H.-W. , Bloebaum C. L.
Published: March 2021

Taguchi’s orthogonal arrays for Robust Design are used in this paper in a non-taditional way to solve a mixed continuous-discrete structural optimization problem. The factors of an orthogonal array correspond to the members of a structure and the levels of each factor correspond to the material choices of each member. Based on the number of factors to be studied and the number of levels of each factor, an appropriate orthogonal array is selected for each specific problem. The number of rows of the orthogonal array correspond to the number of experiments (i.e. continuous sizing optimizations) to be conducted. The response of these experiments, which are the weight of the optimal designs corresponding to different material settings, are then used to calculate the mean effect of each factor level. Some possible optimal material settings can then be determined. Three examples are presented in this paper. Analysis using Taguchi’s orthogonal arrays was able to isolate several near optimal or optimal designs. The accuracy and efficiency of the proposed method compared to more traditinoal solution methodologies are also discussed.
An Object-Oriented Approach to the Engineering Design Process
Authors: Korpela Tapio , Heikkinen Ari , Leinonen Tatu
Published: March 2021

Laboratory of Machine Design at the University of Oulu has modelled the production information for a gear transmission unit in co-operation with a Finnish gear manufacturer, Santasalo Ltd. The basic idea was to integrate computer aided design into modern FMS-based production activities. The main goal in this project is to capture the whole gear box development process from customer requirements to manufacturable assembly and detail information in OOA models.
Kinematic Analysis of Epicyclic-Type Transmission Mechanisms Using the Concept of Fundamental Geared Entities
Authors: Hsieh Hsin-I , Tsai Lung-Wen
Published: March 2021

The kinematic characteristics associated with fundamental geared entities are investigated. By decomposing an epicyclic gear mechanism into two subsystems and each subsystem into two subsystems until the lowest level subsystem contains only one fundamental geared entity, the overall speed ratio of an epicyclic gear mechanism can be conveniently expressed in terms of the speed ratios of the fundamental geared entities. The result can be applied for the identification of feasible clutching sequences of a transmission mechanism.
Dynamic Force and Torque Analysis of a Spherical Four-Bar Mechanism
Authors: Dooley J. R.
Published: March 2021

Spherical four-bar linkages are compact mechanisms capable of motion outside the plane and transmission between intersecting shafts. Dynamic analyses of spherical four-bar linkages are complicated by the fact that they are statically indeterminate. Previous solutions have used an RCCC approximation to model the 4R linkage. This paper extends previous results to include the material elasticity in the dynamic analysis. The results of this more accurate model are compared to those obtained from the RCCC model and it is shown that the RCCC approximation yields significant errors.
Optimal Geometric Design of Robot Manipulator Link Shapes
Authors: Tu Q. , Rastegar J.
Published: March 2021

In a recent article, Rastegar and Tu (1993), the authors presented a method for determining allowable link shapes for robot manipulators once their preferred operational environment is specified. The operational environment may include the preferred size and geometry of the end-effector task space(s), the obstacle and the installation spaces, and the enclosure within which the robot is to operate. In this method, by defining weighted (preferred) distributions for the task and/or obstacle spaces and for the enclosure geometry, weighted allowable manipulator link shapes are determined. In the present study, the developed method is extended to address the problem of optimal geometric design of robot manipulator link shapes. The developed methods are very simple, numeric in nature, readily implemented on computer, and can be classified as being based on the Monte Carlo method. The extension of the present method to the solution of optimal geometric shape synthesis for task and obstacle spaces is discussed. Numerical examples are presented.
Interference Distance Calculation for Two Objects Bounded by Quadratic Surfaces
Authors: Sharf Inna , Nahon Meyer
Published: March 2021

We describe an algorithm for determining the interference or penetration distance between two moving objects. The objects are assumed to be specified by quadratic and/or linear constraints and thus, encompass a wide variety of objects encountered in robotics and multibody dynamics applications. The interference distance problem is formulated as a constrained optimization problem where we maximize the shrinkage of both objects, while maintaining a non-empty intersection volume between them. The key to the present algorithm is a nonlinear transformation which allows a closed-form description of the shrunk bodies. The resultant nonlinear programming problem is solved using an existing optimization scheme which is based on a recursive quadratic programming technique. The paper concludes with a numerical example demonstrating the validity and the computational efficiency of the proposed solution.
Simulation of Automated Robotic Assembly
Authors: Miller Alec R. , Cipra Raymond J.
Published: March 2021

This paper examines the development of a networked simulation system. The Automated Robotic Manipulation (ARM) simulator is a central part of the network. This simulation tool currently assists with research and education into automated assembly. Robots, fixtures, conveyors, and parts create an automated assembly cell which is used to test advanced manufacturing software. ARM animates models of these physical components and enhances them with additional forms of three-dimensional graphical visualization. The feasibility of automated assembly can rapidly be assessed from the visual content presented by the simulator. Input formats for ARM are flexible enough to support a wide range of assembly cells and activities. Files and network transmissions customize the simulator to a particular assembly cell and its activities. The emerging assembly data protocol promotes the development of a truly integrated manufacturing system. A graphical interface complete with multiple views assists assembly cell layout and activity review, and networked operations significantly expand its role to areas such as interactive robot control and assembly preview.
Mathematical Model for Kinematic Analysis of Working Coordinates of General Mechanisms
Authors: Wang J. Y. , Yeh H. J. , Lin T. C. , Wu J. K.
Published: March 2021

Mathematical models have been derived for the kinematic analysis of working coordinates, which contain the formulation of the working coordinates constraint equations in terms of the relative joint coordinates, the transformation of the Jacobian matrix of the associated constraint equations from the Cartesian coordinate space to the relative joint coordinate space, and formulation for velocity and acceleration calculation. Such models lay out a solid foundation for the computational inverse kinematic analysis. In addition, moveable working coordinates are derived for both local and global coordinate systems. Application of this can be the working path design of general manipulators.
Dynamic Frictional Contact of Rubber-Like Bodies
Authors: Szefer Gwidon , Jasińska Dorota
Published: March 2021

In the paper a frictional contact of a high elastic body in terms of dynamics and large deformations has been considered. An effective mixed lagrangean-eulerian formulation and solution of the nonlinear boundary value problem is given. Unilateral contact of a rubber block and a rubber bearing are discused in detailes. Stress distributions, displacements and phase trajectories for chosen points illustrate the result of the paper.
Placement Analysis for a Class of Platform Manipulators
Authors: Ji Zhiming
Published: March 2021

Development in parallel-actuated platform manipulators has opened new applications. Proper placement of a platform manipulator is important for it to meet different workspace and other task requirement. We formulate the placement of platform manipulators with triangle-shaped mobile plate as an optimization problem. This paper presents the derivation of multi-variable objective function for both platform placement and task planning. It also discusses the implementation of the down-hill simplex algorithm, and some data from our initial investigation.
Dexterity of Manipulators at an Operating Point
Authors: Abdelmalek Karim A.
Published: March 2021

This paper presents a method for analyzing dexterity of manipulators comprising spherical wrists. The goal is to provide the user with knowledge of orientability of the end-effector at a target. Wrist accessible output sets are determined analytically by first determining manipulator singularities, followed by back substituting the singularities into the constraint equations to parametrize surfaces. Since regions of a surface may exist inside the wrist accessible output set, and other regions on the boundary, surfaces are segmented into subsurfaces. To determine whether a subsurface is an internal or boundary one, each subsurface is studied for existence inside the wrist accessible output set by perturbing a point along its normal. Closed-form solutions of the boundary of the wrist accessible output set are obtained. A service sphere is located at an operating point in the accessible output set and the sphere is intersected with the boundary sub-surfaces. The intersection curves are computed and projected onto the space of a cylinder, then the cylinder is unrolled to depict a map. Dexterity charts are introduced as maps depicting orientability of the end-effector at a target.
Mass Moment of Inertia of External Geneva Wheels
Authors: Sepahpour Bijan , Fischer Ian S.
Published: March 2021

Equations have been developed and design curves are presented to accurately estimate the mass moment of inertia of the Geneva wheel component in mechanisms used for indexing and intermittent motion applications. The curves are non-dimensionalized so that they can be applied whatever material is used for the Geneva mechanism and whatever units are used for the calculation of the dynamics.
Adaptive Synthesis of Hydraulic Circuits From Design Cases Based on Functional Structure
Authors: Fujita Kikuo , Akagi Shinsuke , Sasaki Makoto
Published: March 2021

An adaptive synthesis method for hydraulic circuits is proposed by using case-based reasoning technique based on their functional structure. Since synthesis of hydraulic circuits is a typical problem of conceptual design and its property is expertise-oriented and combinatorial, it is difficult to declaratively represent useful design knowledge. In our design method, past design cases are afore-stored in the case base, and then a circuit is generated by arranging suitable past cases which are retrieved from the case base in accordance with the difference related to functional structure. In order to measure such functional structure, design specifications are represented with labels. Design cases are adaptively manipulated into a target design with three synthesis strategies, decomposition, series combination and parallel combination, based on surplus or deficit of labels. Moreover, arranged circuits are verified with a logical simulation method based on symbol manipulation. These synthesis and simulation methods are applied to some design problems in order to show their effectiveness and validity.
Probabilistic Design of High Temperature Components Subjected to Low Cycle Fatigue Loads
Authors: Pigott Ronald
Published: March 2021

From the beginning, engineers have focused on the special case of determinism in the design process, and an enormous methodology has been developed to support this approach. Today, however, customers are demanding greater reliability and are imposing greater penalties for failure. In order to achieve higher reliability, and in order to asses risk of failure, probabilistic approaches will almost certainly have to be employed. While designers have always used probability in their work, it has usually been done with risk represented in a single factor of safety. This paper focuses on the application of probability theory to the design of high temperature components which are subjected to low cycle fatigue loads. Creep low cycle fatigue interaction and probabilistic design are both complex subjects. In order to make the probabilistic design of components subjected to creep and low cycle fatigue tractable, the calculation models must be as simple as possible without sacrificing too much on accuracy. In this paper, cumulative damage is determined using Miner’s Rule in conjunction with “range pair” cycle counting. The effect of operation at elevated temperatures is included using Coffin’s frequency modified approach. A first order second moment (FORM) method for including probabilistic effects is developed and some sample calculations are presented. It is shown that the traditional deterministic approach using a single factor of safety does not provide a uniform margin of safety for all design conditions.
Sequential Roundoff for Improving Robot Position Accuracy
Authors: Ji Zhiming
Published: March 2021

A robot can only reach discrete locations within its workspace due to its finite encoder counts. Actual position and orientation reached by end-effectors are therefore the result of roundoff in the encoder counts. Traditionally the roundoff is carried out at the end of inverse kinematics, which produces the propagation and accumulation of the roundoff errors (except for Cartesian type of robot). We proposed a sequential roundoff procedure during the inverse kinematics process to compensate the roundoff errors. Numerical analysis shows that this method can lead to significant improvement in the positioning accuracy. Our study also shows that the sequence with which the inverse is carried out affects the improvement. Selection of sequence for inverse kinematics is discussed.
A Comparison of Architectures of Parallel Mechanisms for Workspace and Kinematic Properties
Authors: Gosselin Clement M. , Ricard Rémi , Nahon Meyer A.
Published: March 2021

This paper presents a study of the workspace and kinematic properties of four different architectures of six-degree-of-freedom parallel mechanisms. For each architecture, the volume of the Cartesian workspace is computed at different orientations of the moving platform. The distribution of the workspace is also found by computing the 2D sections of the 3D workspace. The rotational workspace is then determined at the reference position of the platform. Finally, the stiffness properties of the architectures are obtained. Normalization factors are then defined to account for the structural differences between the architectures of mechanisms. The comparison of the different architectures of parallel mechanisms has been performed using SIMPA, a specialized CAD tool developed for the kinematic analysis and optimization of parallel manipulators. The results thus obtained illustrate the range of performance which can be expected from different parallel architectures. Although none of the architectures proves to be better than all the others in all respects, particular architectures do excel in particular performance measures. The approach proposed would therefore be useful in further studies relating to the design and optimization of parallel manipulators and mechanisms.
A New Shaft Coupling Design for a High-Speed Rotor Wheel
Authors: Kiss Tibor , Ng Wing-Fai , Mitchell Larry D.
Published: March 2021

A high-speed rotor wheel for a wind-tunnel experiment has been designed. The rotor wheel was similar to one in an axial turbine, except that slender bars replaced the blades. The main parameters of the rotor wheel were an outer diameter of 10“, a maximum rotational speed of 24,000 RPM and a maximum transferred torque of 64 lb-ft. Due to the working environment, the rotor had to be designed with high safety margins. The coupling of the rotor wheel with the shaft was found to be the most critical issue, because of the high stress concentration factors associated with the conventional coupling methods. The efforts to reduce the stress concentrations resulted in an advanced coupling design which is the main subject of the present paper. This new design was a special key coupling in which six dowel pins were used for keys. The key slots, now pin-grooves, were placed in bosses on the inner surface of the hub. The hub of the rotor wheel was relatively long, which allowed for applying the coupling near the end faces of the hub, that is, away from the highly loaded centerplane. The long hub resulted in low radial expansion in the coupling region. Therefore, solid contact between the shaft and the hub could be maintained for all working conditions. To develop and verify the design ideas, stress and deformation analyses were carried out using quasi-two-dimensional finite element models. An overall safety factor of 3.7 resulted. The rotor has been built and successfully accelerated over the design speed in a spin test pit.
Internal Variable Modeling of the Creep of Monolithic Ceramics
Authors: White Charles S. , Hazime Radwan M.
Published: March 2021

Ceramics are assuming an important role for use in power generation. One of the road blocks is a complete characterization of the deformation and life of advanced ceramics at elevated temperatures. Substantial high temperature creep testing has been conducted in recent years. Most commonly, Norton’s law for deformation and the Monkman-Grant relationship for failure have been used to correlate test data.

In this paper, internal variable modeling is discussed as an alternative to Norton’s Law/Monkman-Grant. Through the use of internal variables, micromodeling of the important mechanisms can be extended to the macroscopic behavior. Also, the effects of simultaneous or competing phenomena can be considered. An example is the growth of lenticular cavities on the two grain boundaries of certain silicon nitrides while the grain boundaries are crystallizing. The results of a preliminary internal variable model for HIPed silicon nitride is presented and compared with tensile creep experiments.
Shape Definition of Scarred Boiler Tubes and Geometry-Based Implications for Creep Rupture
Authors: Platfoot Robin A. , Zarrabi Khosrow
Published: March 2021

New life assessment procedures are being developed to determine the optimum time when worn or gouged pressure tubing should be removed from tube banks within industrial steam generators. This paper describes a procedure for modeling the volume loss associated with scars of arbitrary shapes which subsequently provides input data for determining remaining tube life. The procedure is designed so that the input measurements may be made with relative ease, irrespective of the complexity of the shape of the damaged site. The basis for this approach is the assumption that, while the sizes of scarred areas vary with each individual occurrence, the shape or profile of the crater is repeatable on a case by case basis. The analysis code has been developed in conjunction with an extensive experimental program to assess the variety of scar shapes which are encountered on tubes removed from coal fired boilers used in power stations. The paper concludes with some preliminary details of how the temperature varies in the scarred section. The estimation of this temperature variation is important for creep life assessments.
Experimental Analysis of an MMC Military Track Shoe
Authors: Strelow Joseph E. , Simula Glen R. , Hughes Craig F. , Pakkala Edward C.
Published: March 2021

This paper describes the experimental analysis techniques used during the design of a prototype military track shoe utilizing cast metal matrix composite (MMC) material for use on future military vehicles. The program requirements were to retain the same functionality, strength, durability and wear characteristics as production forged steel track shoes, but with a significant weight reduction and comparable cost. In order to achieve these goals with such significant differences in mechanical properties, a thoroughly integrated design phase combining analytical modeling and experimental techniques was used.

Finite element analyses were conducted during the initial design phase to optimize the structure. Various experimental techniques were used to validate the computer models and obtain reliable information in regions not accurately modeled. Destructive tests of the final design were also performed to determine failure loads. Experimental techniques were employed in three distinct phases: reflective photoelasticity and strain gage analysis of an aluminum filled epoxy model for initial analytical verification, transmissive analysis of a 3-D photoelastic model, and finally reflective photoelastic and strain gage analysis of the actual prototype MMC shoe. The results from all phases are discussed, but with greater emphasis on the experimental techniques.
The Criteria Predicting Wrinkling of Thin, Flat, Rectangular Webs
Authors: Lin Chen-Chi , Mote Clayton D.
Published: March 2021

A web is termed wrinkled when one of the in-plane principal stresses is tensile and the other is sufficiently compressive. A criterion is derived that predicts wrinkling of isotropic, compressible rectangular webs under uniform in-plane principal stresses. The compressive stress at impending wrinkling depends on the flexural stiffness, and it equals zero in the case of a membrane. A criterion of wrinkling is also derived using isotropic, incompressible membrane theory. This criterion predicts an infinite number of wrinkle waves in a wrinkled region. With small flexural stiffness, the number of wrinkle waves becomes finite at wrinkling and it is predictable along with the shape and the size of the wrinkled region. The number of the wrinkle waves increases as the aspect ratio of the rectangular web increases, as the in-plane principal tension increases, and as the flexural stiffness decreases. Analyses of wrinkling of a rectangular web under simple shear and uniform longitudinal stretching illustrate the above predictions.
Heat Transfer Finite Element Analysis of an Adhesive Bonding Process
Authors: Veldman Roger L. , VandenBrink Dennis J.
Published: March 2021

The finite element method was used to model an adhesive bonding process between a sheet of glass and a long strip of flexible PVC. The effect of the thickness of the PVC strip, the number of heat sources, the temperature of the heat sources, the size of the heat sources, and convection on the steady state temperature distribution in the adhesive layer was studied. The time required to reach the steady-state condition was also determined.
Finite-Element Study of C-Ring Fracture Specimens for the Determination of Design Strength Data
Authors: Segall A. E. , Jadaan O. , Palko J.
Published: March 2021

To investigate the design implications of using C-ring specimens for evaluating the strength controlling flaw population(s) of ceramics when in tubular form, finite-element analysis (FEA) calculations were performed using the ANSYS code. These calculations focused on the ranges of width-to-thickness ratios required to maintain a plane stress state within the C-ring specimen during fracture. In addition, the validity of the theoretical effective-area (KA) and effective-volume (KV) relations derived during earlier analytical and experimental studies were investigated. Results of the FEA calculations indicated that a wide range of width-to-thickness ratios could be safely used to extract fracture strength design data. Moreover, the calculations confirmed the validity of the theoretical stress-area and stress-volume relations used to correlate strength defining flaw population and determine Weibull parameters. However, a tendency for the computational errors to increase with Weibull modulus was observed during the finite-element based estimations of effective-areas and -volumes.
A Method for Assessing the “Local” Accuracy of Weight Functions for Plates With Embedded Cracks
Authors: Ng S. W. , Lau K. J.
Published: March 2021

In this paper a procedure is developed to assess the “local” accuracy of weight functions for finding stress intensity factors of centrally cracked finite plates given by Tsai and Ma (1989). It is found that the weight functions can be used to calculate stress intensity factors for practical cases, with “local” accuracy being within 6 %. In addition, weight functions generated from two finite element analyses are found to be accurate and may be used to assess new algorithms for finding weight functions.
Thermal Vibrations of Beams With Temperature-Dependent Material Properties
Authors: Masoom Abulkhair M.
Published: March 2021

Thin beams subjected to thermal loads are considered. The formulation includes the temperature dependence of thermal conductivity and elastic modulus as well as coupled theory. A comparison is made between beams made of stainless steel and silicon carbide. Results show that significant differences are possible for temperature and stress solutions when temperature-dependent elasticity and conductivity are used, as opposed to the constant properties evaluated at a reference temperature.