bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonality of distinct respiratory viruses in a tropical city: implications for prophylaxis
Authors: Santos Ruth‐Kelly O. , Borges Igor C. , Souza Mariana L. , Bouzas Maiara L. , Nascimento‐Carvalho Cristiana M. 
Published: March 2021

AbstractObjectiveThe frequency and seasonality of viruses in tropical regions are scarcely reported. We estimated the frequency of seven respiratory viruses and assessed seasonality of respiratory syncytial virus (RSV) and influenza viruses in a tropical city.MethodsChildren (age ≤ 18 years) with acute respiratory infection were investigated in Salvador, Brazil, between July 2014 and June 2017. Respiratory viruses were searched by direct immunofluorescence and real‐time polymerase chain reaction for detection of RSV, influenza A virus, influenza B virus, adenovirus (ADV) and parainfluenza viruses (PIV) 1, 2 and 3. Seasonal distribution was evaluated by Prais–Winsten regression. Due to similar distribution, influenza A and influenza B viruses were grouped to analyse seasonality.ResultsThe study group comprised 387 cases whose median (IQR) age was 26.4 (10.5–50.1) months. Respiratory viruses were detected in 106 (27.4%) cases. RSV (n = 76; 19.6%), influenza A virus (n = 11; 2.8%), influenza B virus (n = 7; 1.8%), ADV (n = 5; 1.3%), PIV 1 (n = 5; 1.3%), PIV 3 (n = 3; 0.8%) and PIV 2 (n = 1; 0.3%) were identified. Monthly count of RSV cases demonstrated seasonal distribution (b3 = 0.626; P = 0.003). More than half (42/76 [55.3%]) of all RSV cases were detected from April to June. Monthly count of influenza cases also showed seasonal distribution (b3 = −0.264; P = 0.032). Influenza cases peaked from November to January with 44.4% (8/18) of all influenza cases.ConclusionsRSV was the most frequently detected virus. RSV and influenza viruses showed seasonal distribution. These data may be useful to plan the best time to carry out prophylaxis and to increase the number of hospital beds.
Multidisciplinary Analysis and Optimization of Discrete Problems Using Response Surface Methods
Authors: Korngold Jacob C. , Gabriele Gary A. 
Published: March 2021

Abstract
The objective of this paper is to present a new algorithm to efficiently optimize multidisciplinary, coupled non-hierarchic systems with discrete variables. The algorithm decomposes the system into contributing disciplines, and uses designed experiments within the disciplines to build local response surface approximations to the discipline analysis. First and second order Global Sensitivity Equations are formulated and approximated by experimental data to build approximations to the global design space. The global approximation is optimized using branch and bound or simulated annealing. Convergence is rapid for systems with near quadratic behavior. The algorithm is demonstrated on a unique multidisciplinary learning tool, the Design and Manufacturing Learning Environment. This environment provides multimedia simulation for product life cycle disciplines, including design, manufacturing, marketing, and sales.
Finite Element Dynamic Modeling of Elastic Beam With Prismatic Joint
Authors: Al-Bedoor B. O. , Khulief Y. A. 
Published: March 2021

Abstract
A finite element dynamic model of a translating beam through a prismatic joint is presented. The method adopts a fixed number of elements. The element length, on the contrary to the previously reported models, is constant. The time dependent nature of the boundary conditions is utilized to impose the prismatic joint constraints by varying the stiffness of the transition element. This method preserves all the dynamic coupling terms between the axial rigid body motion and the elastic deformations. The end mass dynamics is conveniently considered in the formulation. Furthermore, the introduced dynamic model offers a convenient formulation that can be incorporated into a general flexible multibody dynamics code and lends itself for control applications. The developed model is evaluated through comparisons with previously reported results of other models.
On Computing Exact Gradients for Rigid Body Guidance Using Screw Parameters
Authors: Bobrow James E. , Park Frank C. 
Published: March 2021

Abstract
The problem of designing a mechanism that comes closest to reaching a desired set of goal positions is examined in this paper. The approach is first applied to spherical four-bar mechanism design synthesis on SO(3), and then extended to general spatial problems on SE(3). For each class of problems, we define a distance metric which is used in a numerical optimization algorithm to determine the optimum design. An important feature of our approach is that analytic gradients of the distance metric are determined in a straightforward manner which can be easily programmed. Once these gradients are known, general purpose optimization packages can efficiently compute locally optimal solutions with excellent convergence properties.
A New Model-Based Tool for Fault Detection and Isolation in Machine- and Rotordynamics
Authors: Söffker Dirk 
Published: March 2021

Abstract
Reliability and safety aspects are becoming much more important due to higher quality requirements, complicated and/or connected processes. The fault monitoring systems to be commonly used in machine- and rotordynamics are based on signal analysis methods. Furthermore, various kinds of fault detection and isolation (FDI)-schemes are already applied to a lot of technical applications of detecting and isolating sensor and actuator failures (Isermann, 1994; van Schrick, 1994) and also to fault detection in power plants (in general) or in manufacturing machines. An implicit assumption is that process or machine changes due to faults lead to changes in calculated parameters, which are unique and unambiguous. In the case of applying methods of signal analysis this means spectrums etc. the vibration behaviour will be monitored very well but have to be interpreted. On the other hand signal parameters usually only describe the system by analyzing output signals without use of known and unknown inner parameters and/or inputs. These parameters are available, and normally this knowledge is used by the operating staff interpreting the resulting signal parameters. In this way a decision-making problem appears so that questions about the physical character of faults, about the existence of special faults and also about the location of failures/faults has to be answered. In this way the experience and knowledge of the interpreting persons are very important. In this contribution the problems of the decision-making process are tried to defuse:
• The available knowledge about the unfaulty system parameters is used to built up beside a nominal system model an unambiguous fault-specific ratio. Inner states of the structure are estimated by an PI-observer.
• The developed robust PI-observer (Söffker et al., 1993a; Söffker et al., 1995a) estimates inner states and unknown inputs.
In (Söffker et al., 1993b) this new method is applied to the crack detection of a rotor, but not proved. In this paper the proof is given and a generalization is described. The advantages in contrast to usual signal based vibration monitoring systems and also modern FDI-schemes are shown.
Trade-Offs in Robust Design: Comparing Optimization, Taguchi’s Approach and Guided Iteration in Three Examples
Authors: Orelup Mark , Dixon John R. 
Published: March 2021

Abstract
The goal of designing for robustness is to produce products, parts, and sub-assemblies that exhibit minimal variation in performance over their lifetime despite variations in their manufacture and operating environment. Achieving both good performance and high robustness is inherently a multi-objective problem. In this paper, three methods for solving this problem (optimization, Taguchi’s approach, and guided iteration using Dominic3) are compared in three case studies. The ability of the methods to respond to different trade-offs between robustness and performance is examined and compared.
A Computer-Based Approach Towards Including Design History Information in Product Models and Function-Means Trees
Authors: Malmqvist Johan 
Published: March 2021

Abstract
This paper describes a computer-based approach towards design history documentation. The approach is based on design theory, more specifically on the “function-means tree” model of the design process and on the “chromosome” model for product modelling.
The realization of this concept requires that a more precise terminology is utilized when developing the function-means tree. In the paper, a number of extensions of the function-means tree terminology are suggested. These include using a wider definition of the function concept, representation of design rationale, constraints and objectives in the tree, and more refined concepts for decomposition of functions and functional requirements.
Preliminary tests of the system have demonstrated the feasibility of the approach. Further tests, based on design problems with more degrees of freedom are needed, to fully assess all aspects of the system, especially concerning the management of constraints and objectives in the extended function-means tree model.
A Taxonomy for Classifying Engineering Decision Problems and Support Systems
Authors: Ullman David G. , D’Ambrosio Bruce 
Published: March 2021

Abstract
The design of even the simplest product requires thousands of decisions. Yet very few of these decisions are supported with methods on paper or on computers. Is this because engineering design decisions don’t need support or is it because techniques have yet to be developed that are usable on a wide basis? In considering this question a wide range of decision problem characteristics need to be addressed. In engineering design some decisions are made by individuals, others by teams — some are about the product and others about the processes that support the product — some are based on complete, consistent, quantitative data and others on sparse, conflicting, qualitative discussions. In order to address the reasons why so little support is used and the characteristics of potentially useful decision support tools, a taxonomy of decision characteristics is proposed.1 This taxonomy is used to classify current techniques and to define the requirements for an ideal engineering design decision support system.
Design for Injection Molding: Balancing Mechanical Requirements, Manufacturing Costs, and Material Selection
Authors: Beiter Kurt A. , Cardinal James M. , Ishii Kos 
Published: March 2021

Abstract
This paper describes a procedure for considering mechanical requirements, manufacturing costs, and material selection in the design of injection molded parts. The benefit of this approach is the simultaneous consideration of the implications of material selection and part geometry on estimated manufacturing cost during candidate design selection. The current implementation uses the allowable deflection of a flat plate as an example performance measure. Manufacturability concerns include required part thickness and gating scheme to adequately mold the part, and a resulting cycle time based on part cooling time estimates. Part manufacturing cost includes material cost, cycle time, and production costs. A PC-based and CAD-integrated program illustrate our proposed procedure.
Virtual Prototyping of Die Design Algorithmic, Computational and Practical Considerations
Authors: Wuerger David , Gadh Rajit 
Published: March 2021

Abstract
This paper presents the implementation of the algorithms used for computing the die-open directions for a near-net-shape manufactured part, using the approach described in part one of this publication (Virtual Prototyping of Die Design - Theory and Formulation). In this approach, a set of concavity features is used to determine the die-open directions for a given part, first by determining the convex hull of the geometry, then by performing a boolean subtraction between the convex hull of the part and the 3-Dimensional solid model of the original part geometry. This will provide the set of concavity features that restrict the possible die-open directions for the part. A set of possible die-open directions is determined for each concavity feature. Subsequently, the set of directions common to all concavity features is determined to be the set of die-open directions for the part. The convex hull of a part (or a convex part) has unrestricted draw, implying that a convex part can be oriented in any fashion inside a die. The algorithms for this approach, its computational analysis, and strengths and weaknesses of the implementation are discussed in the current paper.
Modeling Contact/Impact in Hybrid Parameter Multiple Body Mechanical Systems: Extensions for Higher Order Continuum Models
Authors: Barhorst Alan A. 
Published: March 2021

Abstract
In recent work the author presented a systematic formulation of hybrid parameter multiple body mechanical systems undergoing contact/impact motion. The method rigorously modeled all motion regimes of hybrid multiple body systems (i.e. free motion, contact/impact motion, and constrained motion), utilizing minimal sets of hybrid differential equations. The contact/impact regime was modeled via the idea of instantaneous non-holonomic constraint application. The technique previously presented did not include the possibility of continuum assumptions along the lines of Timoshenko beams, higher order plate theories, or rational theories considering intrinsic spin-inertia. In this paper, the above mentioned method is extended to include the higher order continuum assumptions which eliminates some of the continuum shortfalls from the previous work.
Vibration Control of a Beam Embedded With an Electrorheological Fluid
Authors: Selstad Tyler J. , Farhang Kambiz , Chelidze David 
Published: March 2021

Abstract
Electrorheological (ER) fluids are known to exhibit damping and stiffness properties which are highly dependent on the induced electrical field strength within the ER medium. Incorporation of ER fluid within a structural member then provides a means of stiffness and damping variation of the member. A structural member with embedded ER fluid is considered. Equations governing the axial and transverse motions of the member are reduced to a system of linear ordinary differential equations with time-varying coefficients. Application of the multiple time scales method results in amplitude-frequency relations. A control method is considered in which the effect of embedded ER fluid damping modulation using a simple harmonic excitation voltage on the parametric stability boundaries of the member is examined. Results indicate that the parametric stability boundaries can change effecting various modulation amplitudes and frequencies.
Optimization of Stochastic Multibody Systems
Authors: Eberhard Peter , Schiehlen Werner , Bestle Dieter 
Published: March 2021

Abstract
The multibody system approach is used for the investigation of mechanical systems with large motions, e.g. in vehicle dynamics and robotics. Important modules of a computer-aided tool proposed for analysis and optimization are filtering techniques and scalar optimization algorithms. Formfilters are used for the creation of stochastic exciations and criterion computations.
Typical properties of deterministic and stochastic scalar optimization algorithms with application to dynamic systems are presented and a hybrid deterministic-stochastic approach is proposed which combines the advantages of both algorithm types. An application to vehicle dynamics clarifies the optimization concept.
Maximum Entropy Closure for Nonlinear Stochastic Systems
Authors: Sobczyk Kazimierz , Trębicki Jerzy 
Published: March 2021

Abstract
The statistical moments of the response of nonlinear stochastic systems are governed by an infinite hierarchy of equations. In order to evaluate the most important low order moments suitable closure schemes are necessary. In this paper a non-Gaussian closure procedure is presented which is based on the maximum entropy principle developed recently by the authors in the context of stochastic nonlinear dynamics.
Variability in Dynamic Response of Non Self-Adjoint Mechanical Systems
Authors: Venkatesan S. , Ganesan R. 
Published: March 2021

Abstract
Variations in strength, geometric and deterioration characteristics of both materials and machine components are quite common in real-life mechanical systems due to manufacturing defects and measurement errors. Such inherent fluctuations which are unavoidable even with the best quality control measures, are essentially random in nature. Effects of these random fluctuations on the performance levels, dynamic response and service life of mechanical systems need to be evaluated based on a stochastic approach, in order to assist design and diagnostics of industrial machinery. Non self-adjoint eigenproblems that correspond to the dynamic response of complex mechanical systems such as high speed rotors, fluid-flowing pipes and actively controlled structures are considered in the present work. The coefficients of the matrices are stochastic processes and are resulting from uncertain parameters of the mechanical system being described by the eigenproblem. A perturbational solution is sought and obtained in a form that does not involve repeated solutions of a recursive set of equations. Sample functions are generated based on the perturbational expansion and response moments are obtained by treating uncertain fluctuations to be stochastic perturbations. Complete covariance structures of both eigenvalues and eigenvectors are obtained through computationally efficient expressions. Applications of the developed procedure for real-life mechanical systems, that have uncertain material properties, are demonstrated.
Chaotic Vibration in Aircraft Braking Systems
Authors: Özbek M. Akif , Liu Steve Y. , Gordon James T. , Newman David S. , Atilgan Ali R. 
Published: March 2021

Abstract
Typical vibration modes of aircraft braking systems are discussed in this paper. Special attention is given to squeal vibrations of carbon brakes. From flight tests, a wide range of response amplitudes are analyzed to determine the nature of the motion. Fourier analysis indicates the presence of a high amplitude limit cycle which seems to be initiated by a transient chaotic region. A singular system approach based on a time delay embedding confirms this finding. Time delay analysis makes it possible to contruct model equations via which intrinsic dynamics of the system can be recovered, and opens up the possibility of preventing large amplitude vibration by controlling the chaotic motion.
A Transient Infinite Element for Multi-Dimensional Acoustic Radiation
Authors: Astley R. Jeremy 
Published: March 2021

Abstract
A novel family of infinite “wave envelope” elements is proposed for the solution of transient wave problems in unbounded regions. The elements are formed by applying an inverse Fourier transformation to a discrete wave envelope model in the frequency domain. This gives a coupled system of second-order equations which are readily integrated in time to yield transient pressure histories at nodal points on the surface of the radiating body and — in retarded form — at discrete points within the infinite domain. The infinite elements formed in this way can be applied quite generally to two-dimensional and three-dimensional problems and are fully compatible with conventional finite acoustical elements. They can be used to model radiating bodies of arbitrary shape but are demonstrated in the current instance in application to test problems which involve sound fields generated by spherical surfaces excited from rest, the exterior region being modeled by finite and infinite elements with explicit transverse interpolation. The computed transient solutions obtained from this formulation are compared to analytic solutions and shown to yield accurate results over a full range of exciting frequencies. The utility of the method for problems which involve broadband excitation is confirmed by comparisons of computed and analytic surface impedances for the steady harmonic case. These indicate that the accuracy of the scheme is limited only by a requirement to match element order to the highest order multi-pole component present in the radiated field. That is to say, elements of radial order 1 give an exact solution for monopole fields at all frequencies; elements of order 2 give an exact solution for dipole fields; elements of order 3 give an exact solution for quadrupole fields and so on. Similar results are presented for the fully three dimensional case. These support the extension of this hypothesis to three dimensional transient solutions subject only to the normal limitations imposed by spatial resolution in the transverse direction.
Vibration Control of Rotor Systems With Noncollocated Sensor/Actuator by Experimental Design
Authors: Yang S. M. , Sheu G. J. , Yang C. D. 
Published: March 2021

Abstract
This paper presents a controller design methodology for vibration suppression of rotor systems in noncollocated sensor/actuator configuration. The methodology combines the experimental design method of quality engineering and the active damping control technique such that their advantages in implementation feasibility and performance-robustness can be integrated together. Compared with LQ-based design, the controller order is smaller and it is applicable to systems in an operation speed range. In addition, neither preselected sensor/actuator location nor state measurement/estimation is needed. By using the locations of sensor/actuator and the feedback gains as design parameters, the controller is shown to achieve the best possible system performance while maintaining the closed loop system stability. Analyses also show that, contrary to common believe, the performance of a closed loop system with noncollocated sensor/actuator can be superior to that with a collocated one.
Application of Harmonic Shape Function in Finite Element Modal Analysis
Authors: Surampudi R. , Gupta A. 
Published: March 2021

Abstract
Existing element types available in finite element codes typically utilize polynomial shape functions to define the displacement field in the problem of interest. The polynomial shape functions serve the purpose adequately in static analysis where the displacements and the stresses in a structure are of primary interest. These shape functions give rise to increasing inaccuracy for higher natural frequencies. It is shown that harmonic shape functions yield better results for the higher natural frequencies with same element count. Axial vibrations of bars and transverse vibrations of beams have been analyzed using harmonic shape functions. A comparative analysis has been made between results predicted by the harmonic interpolation functions and polynomial interpolation functions using same number of nodes.