bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling and Analysis of the Control System of a Satellite Tracking Antenna
Authors: Daffron William C. , Vu Hung V. 
Published: March 2021

Abstract
In this paper a model is developed for the 60-foot satellite tracking antenna at Vandenberg Tracking Station (VTS). The model includes the control system, the motors, and the antenna structure. The antenna performance is simulated, using MATRIXX/SystemBuild, for two kinds of inputs: step functions and satellite passes. The predicted antenna performance is then compared to real antenna data, that was recorded at VTS, in order to demonstrate the accuracy of the model. Finally, the model is used to predict the antenna performance on a satellite pass for which no real data is available. The model shows that the antenna is capable of performing this pass with tracking errors less than the specified 2 milliradians (0.114°).
Acoustic Impact Technique for Characterization of Defects in Laminated Composites
Authors: Haque A. , Raju Pollapragada K. 
Published: March 2021

Abstract
The Acoustic Impact Technique (AIT) of nondestructive testing (NDT) has been investigated in detecting gross defects such as delamination in laminated composites. The use of Acoustic Impact Technique has shown encouraging results by previous investigators in identifying defects like delamination and disbonds in honeycomb structures. Very limited work has been reported in the literature about the utility of AIT as a NDT tool for testing in laminated structures. The present work investigates the sensitiveness of the AIT method in detecting delamination in laminated composites in terms of size, shape, position and degree of concentration. The significant advantage of AIT is that this technique is attractive for field applications. The method involves striking the structure with an instrumented impacter in the region of interest and recording the time history of the impulse. The response of the signals received from both good and defective zones of a specimen were analyzed in the time domain. The experimental configuration used by previous investigators was very restrictive. In this study a different approach to AIT is developed. The effectiveness of AIT was evaluated by making a comparative study with ultrasonic C-scan in detecting similar types of defects.
The results indicate the sensitiveness of AIT in detecting delamination in laminated composites in terms of size, depth and degree of concentration.
Transverse Vibrations of a Roller Chain Drive With a Tensioner
Authors: Choi Woosuk , Johnson Glen E. 
Published: March 2021

Abstract
A dynamic model for analysis of the performance of roller chain drive with a tensioner is presented. The model is based on the axially moving material model first given by Mote, but includes extensions that allow consideration of the effects of polygonal action, impact, and the periodic span length changes. Three equations of motion are obtained — one for the tensioner and one for each of the chain spans. The motion of the tensioner interacts with the motions of the chain spans through the chain tension, the contact angles, and the transverse displacement changes of the contact points. The effects of the periodic length change, tensioner stiffness, tensioner damping, tensioner position and external periodic load are investigated. Some of the results are compared to those obtained for a comparable chain drive without a tensioner. Solutions are obtained by a finite difference method.
Dynamics of Curved Beams Undergoing Large Overall Motions Using the Mode Decomposition Concept
Authors: D’Costa Joseph F. , Stolarski Henryk K. , Erdman Arthur G. 
Published: March 2021

Abstract
A fully nonlinear formulation for the dynamics of initially curved and twisted beams, undergoing arbitrary spatial motions, is presented. The formulation admits finite bending, shearing and extension of the beam. The Mode decomposition method is employed to modify the strains in the finite element discretization process leading to the elimination of shear and membrane locking phenomena that arise in curved elements. The model incorporates all inertia effects and is capable of accurately capturing the phenomena of dynamic stiffening due to the coupling of the axial and membrane forces to the flexural deformation. All motion is referred to the inertial frame. The nonlinear formulation is suitable for modeling flexible multibody systems. Examples are presented to illustrate the validity of the proposed formulation.
Interval Analysis of Vibrating Systems
Authors: Dimarogonas Andrew D. 
Published: March 2021

Abstract
Interval calculus is a tool to evaluate a mathematical expression for ranges of values of its parameters. The basic mathematical operations are defined in the interval algebra.
Vibrating systems having system parameters, initial conditions or forcing functions defined as intervals rather than single-valued quantities have been modeled with interval calculus.
The eigenvalue problem for determining natural frequencies and vibrating modes of a system in the case of system matrix elements given as a range of values cannot be solved by exhaustion due to the prohibitively large number of solutions of the point-number eigenvalue problem. Eigenvalue solution with interval evaluation of the commonly used numerical techniques is not feasible because if they are applied directly, the solution intervals diverge. An optimization technique was used to obtain the minimum-radius intervals of the solution. To assure monotonicity and absolute inclusion, necessary for convergence to the exact interval, a converging interval halving sequence was developed. For numerical tests of the method a Monte Carlo solution was developed. Results showed that interval analysis can predict the range of the eigenvalues with sufficient accuracy.
The response of a linear system to general excitation for interval matrices of the system parameters cannot be found with interval evaluation of the commonly used numerical techniques because if they are applied directly, the solution intervals diverge. Interval modal analysis and the interval solution of the eigenvalue problem were developed.
An application is presented for the dynamic response of a rotor with interval bearing properties.
Inelastic Analysis of Reinforced Concrete Shear Wall Structures Under Seismic Excitation
Authors: Wang Ming L. 
Published: March 2021

Abstract
During strong ground motions, members of reinforced concrete structures undergo cyclic deformations and experience permanent damage. Members may lose their initial stiffness as well as strength. Recently, Los Alamos National Laboratory has performed experiments on scale models of shear wall structures subjected to recorded earthquake signals. In general, the results indicated that the measured structural stiffness decreased with increased levels of excitation in the linear response region. Furthermore, a significant reduction in strength as well as in stiffness was also observed in the inelastic range. Since the in-structure floor response spectra, which are used to design and qualify safety equipment, have been based on calculated structural stiffness and frequencies, it is possible that certain safety equipment could experience greater seismic loads than specified for qualification due to stiffness reduction. In this research, a hysteresis model based on the concept of accumulated damage has been developed to account for this stiffness degradation both in the linear and inelastic ranges. Single and three degrees of freedom seismic Category I structures were analyzed and compared with equivalent linear stiffness degradation models in terms of maximum displacement responses, permanent displacement, and floor response spectra. The results indicate significant differences in responses between the hysteresis model and equivalent linear stiffness degradation models. The hysteresis model is recommended in the analysis of reinforced concrete shear-wall structures to obtain the in-structure floor response spectra for equipment qualification. Results of both cumulative and one shot tests are compared.
Structural Dynamic Theory in Health Monitoring
Authors: Ju Frederick D. 
Published: March 2021

Abstract
The paper studies the global methods in monitoring structural health. The principle of global methods is based on the structural dynamic theorems. There are four theories available; namely, (1) the random decrement theory, (2) the modal frequency theory, (3) the transmissibility theory, and (4) the modal shape theory. This paper addresses specifically the modal frequency theory and the transmissibility theory, and their application to the location of fracture damages and the intensity of the damages. The reliability and health assessment depends on the accurate modeling of the damaged structure. With the damage assessment, the paper proposes a method to estimate the upper bound of reliability of the structure, during the hysteretic cycling of the loading.
Interval Analysis of Neural Net Adaptive Expert Systems for Diagnosis of Machinery Incipient Failure
Authors: Dimarogonas Andrew D. 
Published: March 2021

Abstract
Interval calculus is a tool to evaluate a mathematical expression for ranges of values of its parameters. The basic mathematical operations are defined in the interval algebra.
Neural networks is an approach leading to engineering expert systems that are capable of learning, self adapting to particular engineering applications and handling fuzzy and interval input information.
In traditional machine learning, symbolic representations, such as first order predicate calculus, are used to represent knowledge. The resulting algorithms are specific to the selected representation and presume an ad-hoc knowledge of the system represented. In the neural network representation, knowledge is distributed to a large number of weighted synapses that facilitates learning by experience, realized through modification of the synapses weights according to a chosen learning rule.
Traditional classification systems use binary logic. This assumes a clear distinction between two and only two possible states of an event. However, key elements in the human thinking are not numbers but labels of fuzzy sets, that is, classes of objects in which the transition from non-membership to membership is gradual rather than abrupt and ranges of key parameters involved.
A heteroassociative neural network is used to map the existing knowledge and acquire new knowledge in learning sessions. The inputs can be binary, fuzzy and interval variables. To process the diagnosis in a back-propagation mode, interval calculus is utilized in algebraic and matrix operations and the diagnosis results in interval output parameters, the identification scores.
Interval calculus was programmed in a software package to allow for interval computations. The package includes arithmetic, function and matrix operations. Available experience for failure diagnosis in turbomachinery was utilized to initially teach the system. Additional diagnoses from the author’s experience were taught to the system and additional features and diagnoses defined.
Convergence of the procedure depends on the monotonicity of the functions used. For usual networks and threshold functions, convergence is warranted.
Comparative Signature Analysis Using Needle Bearings
Authors: Campbell Craig M. , Tavakoll Massoud S. 
Published: March 2021

Abstract
Many signature analysis techniques have been developed for detecting bearing damage. In this paper, a number of these techniques are evaluated and their abilities to detect the existence and progression of damage are quantitatively compared. Needle bearings are used for this evaluation because they are noisier than ball bearings, and there has been little published regarding their vibration behavior. The signature analysis techniques are evaluated using three increasing levels of outer race damage. The Evaluation criteria are based on the ability of a technique to repeatedly detect a damaged bearing and to correctly indicate the progression of damage level.
Correlation of the SPICE Beam Expander Structural Model With Component and System Level Modal Test Results
Authors: Mimovich Mark E. 
Published: March 2021

Abstract
A full scale experimental beam expander structure is modeled and correlated with modal test results on a component and system level. Correlation of the FE models is completed using the LINK module of the Leuven Measurement Systems (LMS) software which is also used to acquire and reduce the modal test data. The correlation tools used to measure the agreement between test and analytic mode shapes are the Modal Assurance Criterion (MAC), Coordinate Modal Assurance Criterion (CoMAC), and mass cross-orthogonality. In addition to the tools used to measure agreement between test and analysis modal parameters, sensitivity and optimization algorithms are used to identity structural parameters which influence a particular mode and what the minimum change(s) must be in the parameter(s) to bring about the desired agreement. As part of a system level pre-test analysis, the theoretical mode shapes along with a normalized line-of-sight error associated with each mode are used to select the best measurement and excitation locations.
Mixed Planar and Spatial Modeling for Multibody Dynamics
Authors: Freeman Jeffrey S. , Velinsky Steven A. 
Published: March 2021

Abstract
In the process of formulating and analyzing multibody dynamics problems, situations often arise where the desire to mix planar and spatial models naturally occurs. In the analysis of vehicle powertrains, for example, there are relatively few spatial bodies, such as the engine and transmission casing, but many planar elements, such as the gearing inside the transmission. The current study differs from prior work using Euler-Lagrange techniques by developing the ability to mix three-dimensional component body and two-dimensional planar kinematic elements within a single system model. While this study was performed specifically for the modelling of vehicle powertrains, the assumptions, analysis and transformations that enable planar elements to be mixed with spatial bodies are of broad applicability in the field of multibody dynamics.
On the Dynamics of a Rotary Compressor: Part 1 — Mathematical Modeling
Authors: Padhy Sisir K. 
Published: March 2021

Abstract
The rotary compressor has been used in room air conditioners as well as in refrigerators for many years. Although a number of published papers has been reported on rotary compressor, in the area of dynamics only a few are found. In addition only one paper describes experimental validation with some agreement with theoretical results. Again the effect of various operating pressures and temperatures, rotational speed of shaft etc. is not fully covered in any published literature. The present paper analyzes the rotary compressor dynamics in detail. The mathematical model, the solution procedure using Runge-Kutta method, and the bearing dynamics are described. The second part of this papers describes the experimental validation and sensitivity study using different variables that affect the compressor dynamics.
Kinematics of the Generalized Slider-Crank Mechanism
Authors: Fischer Ian S. , Rahman Sahidur 
Published: March 2021

Abstract
Dual-number techniques are used to analyze the kinematics and dynamics of the slider crank mechanism generalized to consider the effects of the cylinder axis being offset and non-perpendicular to the crankshaft axis, conditions which result in reciprocating machinery such as engines and compressors from manufacturing tolerances. The kinematics of the mechanism are evaluated with a Newton-Raphson method using dual-number coordinate-transformation matrices which in this work is extended to include mechanisms with spherical joints. Results for various cases are shown and are ready to be used in a study of the dynamics of the generalized slider-crank.
A Compromise Decision Support Problem for Axiomatic and Robust Design
Authors: Bras Bert , Mistree Farrokh 
Published: March 2021

Abstract
Compromise Decision Support Problems (DSPs) are used to model engineering decisions involving multiple trade-offs. In this paper, we focus on how to use such decisions models to perform Axiomatic and Robust Design. A compromise DSP formulation is presented and solved for the concurrent achievement of the functional requirements, Suh’s independence axiom and information content axiom. A model for the selection of principal design parameters from a set of design parameters is included in this compromise DSP formulation. Taguchi’s signal to noise ratio is used as a metric for the reduction of the information content and increasing the robustness of the design. As an example, the design of a compromise DSP for designing an electrical network is used.
Development of a Unified Exact Gradient Approach to Optimal Synthesis of Mechanisms
Authors: Mariappan Jawaharlal , Krishnamurty Sundar 
Published: March 2021

Abstract
This paper presents the development of a unified approach to optimal synthesis of mechanisms using exact gradients. The uniqueness of this approach lies in its ability to find optimal solutions to different type of mechanism problems in a systematic and efficient manner. In this approach, the exact gradients necessary for optimization are developed using a generalized methodical solution procedure based on matrix methods. This enables direct utilization of efficient gradient-based optimization methods in the mechanism synthesis process, thus eliminating the need for time-consuming direct search methods, or, the use of finite difference approximate methods to estimate gradients during optimization. The development of exact gradients and its integration with mechanism synthesis process, thus, offers the most effective approach for finding optimal solutions in generic mechanisms.
Genetic Algorithms As an Approach to Configuration and Topology Design
Authors: Chapman Colin D. , Saitou Kazuhiro , Jakiela Mark J. 
Published: March 2021

Abstract
The Genetic Algorithm, a search and optimization technique based on the theory of natural selection, is applied to problems of structural topology optimization. Given a structure’s boundary conditions and maximum allowable design domain, a discretized design representation is created. Populations of genetic algorithm “chromosomes” are then mapped into the design representation, creating potentially optimal structure topologies. Utilizing genetics-based operators such as crossover and mutation, generations of increasingly-desirable structure topologies are created.
In this paper, the use of the genetic algorithm (GA) in structural topology optimization is presented. An overview of the genetic algorithm will describe the genetics-based representations and operators used in a typical genetic algorithm search. After defining topology optimization and its relation to the broader area of structural optimization, a review of previous research in GA-based and non-GA-based structural optimization is provided. The design representations, and methods for mapping genetic algorithm “chromosomes” into structure topology representations, are then detailed. Several examples of genetic algorithm-based structural topology optimization are provided: we address the optimization of beam cross-section topologies and cantilevered plate topologies, and we also investigate efficient techniques for using finite element analysis in a genetic algorithm-based search. Finally, a description of potential future work in genetic algorithm-based structural topology optimization is offered.
First-Order Necessary Conditions for Robust Optimality
Authors: Cagan Jonathan , Williams Brian C. 
Published: March 2021

Abstract
The first-order necessary conditions of optimality are extended to include information about robust design — cost insensitivity to model inaccuracies and changes in design specification, as well as the manufacturing tolerances treated in more traditional approaches. In these extended conditions, the Lagrangian is formulated as a tradeoff between cost and cost variability, where variability is measured as the flatness and curvature of the objective relative to local variations in design variables and constraints. During optimization these conditions allow cost and robustness to be considered simultaneously at each iteration.
Manus Colobi: Preliminary Results on the Design of a Mechanical Hand for Industrial Applications
Authors: Gosselin Clément M. , Montambault Serge , Gosselin Claude J. 
Published: March 2021

Abstract
This paper presents the kinematic and mechanical design of Manus Colobi, a robotic mechanical hand developed for industrial applications. A review of the design constraints and a general discussion of the objective tasks to be performed by the hand are first presented. This leads to a description of the kinematic properties and the mechanical design of the hand. Applications envisioned for the hand are robust industrial tasks involving rather large forces which justifies the new design presented here.
On Singularities of Planar Parallel Manipulators
Authors: Mohammadi Daniali H. R. , Zsombor-Murray P. J. , Angeles Jorge 
Published: March 2021

Abstract
The singularities of the Jacobian matrices of two manipulator with three degrees of freedom are analyzed. One is a planar 3-legged manipulator; the other, a planar double-triangular manipulator. A general classification of parallel-manipulator singularities into three groups is described. The classification scheme relies on the properties of the Jacobian matrices of the manipulator. Finally, the three types of singularity are identified for the two manipulators.
Multiobjective Optimization of Fiber Composite Shells for Maximum Buckling Load and Imperfection Tolerance
Authors: Zimmermann Rolf H. 
Published: March 2021

Abstract
The performance of thin-walled structures, which are endangered by buckling, is often strongly influenced by geometrical imperfections. It is impossible to know in advance the imperfections, which will be present in the real structure. Nevertheless, their influence has to be taken into account already at the design process. Attempts to identify characteristic imperfections due to specific manufacturing processes overcome this difficulty only partly, as they do not consider imperfections coming into existence after fabrication. The remedy is, to build imperfection tolerant structures. For that purpose, a simple means to measure imperfection tolerance is defined, and a multiobjective optimization formulation is proposed to design fiber composite shell structures, which simultaneously exhibit high imperfection tolerance and high buckling load. By example of axially compressed CFRP cylindrical shells first computational and experimental results are given to demonstrate the feasibility of the concept, and to identify needs for further research.
Integration of Parametric Modeling and Structural Analysis for Optimum Design
Authors: Rasmussen John , Lund Erik , Olhoff Niels 
Published: March 2021

Abstract
The ideas and methods behind a new system, ODESSY, for optimum mechanical engineering design are described. The motivation behind this work is found in the current trend toward unification of engineering design tools which were previously developed and used separately, namely geometric modeling in the form of CAD systems, and mechanical analysis in the form of finite element programs. The united capabilities of these techniques allow for a major step forward in Mechanical Engineering Design, i.e. from tools aimed at analysis to tools aimed directly at synthesis.