bluuebunny/crossref_metadata_2025_split huggingface dataset:
Matrix-Free Iterative Methods for Parallel Finite Element Computations in Acoustics
Authors: Malhotra Manish , Pinsky Peter M. 
Published: March 2021

Abstract
In this paper we consider the iterative solution of non-Hermitian, indefinite and complex-valued matrix problems arising from finite element discretization of time-harmonic acoustics problems in exterior domains. The computational model is based on using Galerkin least squares finite element methods for the acoustic fluid, combined with the non-local Dirichlet-to-Neumann map as the radiation boundary condition. The emphasis here is to develop efficient computational procedures that are suitable for parallel iterative solution of large-scale problems. In this context, we develop a low-storage implementation of the non-local DtN map which allows the use of this exact boundary condition without any storage penalties related to its non-local nature. In order to accelerate iterative convergence, we consider a multilevel preconditioning approach based on the h-version of the hierarchical finite element method. Finite element formulations that employ hierarchical shape functions yield better conditioned matrices than formulations based on the usual Lagrange functions. This improved conditioning translates into a faster rate of convergence if projections between nodal and hierarchical basis functions are used to construct the preconditioning operator. We present numerical results for the solution of two-dimensional scattering problems to examine convergence rates that are realized on practical discretizations.
Transient and Time-Harmonic Infinite Elements for Near-Surface Computations of Three-Dimensional Structures Submerged in a Half-Space
Authors: Kallivokas Loukas F. , Bielak Jacobo 
Published: March 2021

Abstract
This paper is concerned with the numerical solution by the finite element method of transient and time-harmonic three-dimensional acoustic scattering problems in infinite and semi-infinite domains. Its main objective is to illustrate how a local second-order surface-only infinite element — either transient or time-harmonic — developed recently for the three-dimensional wave equation in a full-space can be applied readily to scattering problems with penetrable objects near a planar free surface. Taking a problem in structural acoustics as a prototype, the combined infinite element-finite element method is used here to determine the total and scattered pressure patterns generated when a traveling plane wave impinges upon a structure of general geometry submerged in an acoustic fluid in half-space. One key feature of this methodology is that the ordinary differential equations that result from the spatial discretization maintain the symmetry and sparsity associated with problems defined only over interior domains; the resulting equations can then be solved by standard step-by-step time integration techniques. Thus, the combination of low bandwidth matrices with the ease of use of the infinite elements places the method in an ideal position to meet the large computational demands typically associated with large-scale underwater acoustics problems.
The Modified Boundary Element Method for Vibration and Sound Radiation Prediction of Fluid-Loaded Structures
Authors: Bernblit Michael V. 
Published: March 2021

Abstract
The objective of this study is to modify the conventional Boundary Element Method (BEM) to enable rigorous account of fluid loading. For this purpose the two-level BEM has been developed which allows to split structural and acoustical phases of the problem into two sequential stages. At first step fluid loading is ignored and the in-vacuo normal component of the surface velocity and structural Green’s function are calculated. Then surface pressure distribution is computed from the modified Boundary Integra] Equation with perturbated kernel. Secondly, vibration velocity of fluid-loaded surface is calculated using convolution of the surface pressure and the in-vacuo Green’s function. After that sound pressure is predicted for any control point by Helmholtz formula. The method is applied for volume and planar fluid-loaded radiators as well as to sound scattering by elastic bodies.
A Review of the Developments in the Boundary Element Method for Time-Domain Elastodynamics
Authors: Kaljević Igor , Saigal Sunil 
Published: March 2021

Abstract
The boundary element formulations for two-dimensional time-domain transient elastodynamics are reviewed in this paper. Several improvements of present formulations regarding the numerical integration of boundary element kernels and analysis of symmetric domains are presented. The deterministic transient formulations are next applied for analyzing problems with spatially random boundary conditions. The deficiencies of the present formulations are summarized and possible improvements are suggested.
Analysis and Experimental Evaluation of Inherent Instability in Electromagnetic Eddy-Current Dampers Intended for Reducing Lateral Vibration of Rotating Machinery
Authors: Kligerman Yuri , Grushkevich Asif , Darlow Mark S. , Zuckerberger Adrian 
Published: March 2021

Abstract
There have been a number of papers published that concern the design and operation of electromagnetic, eddy-current dampers for controlling lateral vibration of rotating machinery. Many of these papers have included analysis approaches and all have been generally effective for low-speed operations. There have been a few reports concerning high-speed (supercritical) operations and many of these have indicated instability problems, but none of these have provided a valid analysis to account for instability. That is, all of the analytical approaches have ignored the disk rotation, relative to the magnetic field, and no obvious sources of instability have been found. In this paper, we will present our work in which we have rederived the analyses of this system in which we have not made the common assumption of no rotation between the disk and the magnetic field. In this case, the potential of instability for supercritical speed operation is clear and, in fact, the equivalent negative damping contribution of the eddy-current damper, under these conditions, has a negative effect on the system even if not fully unstable. We have carefully performed a series of experimental tests which corroborate this analytical approach. Finally, we briefly discuss alternative eddy-current damper design approaches that could be considered to provide effective damping at all speeds and avoid these instability problems.
Vibration Analysis of Metal/Polymer/Metal Components
Authors: Mignery Lezza A. 
Published: March 2021

Abstract
In this report, a practical finite element design method is developed for metal/polymer/metal laminated components. An analysis is presented which will predict the damping characteristics of laminated structures. Predictions of natural frequencies, loss factors, and frequency responses are compared to experimental data and closed form solutions for simple geometries. The analysis is then used to determine the damping characteristics of a laminated design. It is then shown how to use the analysis to improve the damping quality of the component. With the methods presented here, components may be designed which reduce vibrations, noise, and fatigue wear by means of a practical finite element approach.
Complete Balancing of Multicylinder Engines Without Requiring Harmonic Balancers
Authors: Bagci Cemil 
Published: March 2021

Abstract
Presently used balancing methods for multicylinder engines and pumps are for partial balancing. As a result the complete shaking force, shaking torque, and shaking moment balancings of engines require the use of harmonic force and harmonic torque and moment balancers. This article presents a new method for complete shaking force and shaking moment balancing of multicylinder engines that requires no harmonic balancers. This is achieved by keeping the total center of mass of each slider crank loop stationary, where the design equations are developed using a linearly independent mass vector method. Balancing the shaking force also balances the shaking moment. Shaking torque is balanced by eliminating the angular momentum of each mechanism loop and by arranging the phase angles of the crank throws. Four-, six-, and eight-cylinder engines are balanced in the numerical examples given. Two methods of completely balancing single-cylinder engines are also given.
On the Number of Modes Required to Observe Forces in Flexible Structures
Authors: Clark William W. , Kim Joo Hyung , Marangoni Roy D. 
Published: March 2021

Abstract
The number of required modes to provide accurate force information in a truncated model of a flexible structure is investigated. In the context of modal truncation of a distributed parameter system, the difference in convergence rates between displacements and forces is discussed. The residual flexibility, a term from past literature, is used to recapture some of the lost force information in a truncated model. This paper presents numerical and experimental results of a study where the residual flexibility is used in conjunction with a Kalman filter so that accurate force information may be obtained from a small set of displacement measurements with a reduced-order model. The motivation for this paper is to be able to obtain accurate information about dynamic bearing loads in a rotating machine for diagnostic and control purposes.
Regularization of Some One-Dimensional Inverse Problems for Identification of Nonlinear Surface Phenomena
Authors: Groetsch C. W. , Hanke Martin 
Published: March 2021

Abstract
A simple numerical method for some one-dimensional inverse problems of model identification type arising in nonlinear heat transfer is discussed. The essence of the method is to express the nonlinearity in terms of an integro-differential operator, the values of which are approximated by a linear spline technique. The inverse problems are mildly ill-posed and therefore call for regularization when data errors are present. A general technique for stabilization of unbounded operators may be applied to regularize the process and a specific regularization technique is illustrated on a model problem.
Determination of Modal Residues and Residual Flexibility for Time-Domain System Realization
Authors: Alvin Kenneth F. , Peterson Lee D. 
Published: March 2021

Abstract
A linear least-squares procedure for the determination of modal residues using time-domain system realization theory is presented. The present procedure is shown to be theoretically equivalent to residue determination in realization algorithms such as the Eigen-system Realization Algorithm (ERA) and Q-Markov COVER. However, isolating the optimal residue estimation problem from the general realization problem affords several advantages over standard realization algorithms for structural dynamics identification. Primary among these are the ability to identify data sets with large numbers of sensors using small numbers of reference point responses, and the inclusion of terms which accurately model the effects of residual flexibility. The accuracy and efficiency of the present realization theory-based procedure is demonstrated for both simulated and experimental data.
Convergence and Large Deviations in a Bayesian Approach to Functional Estimation Problems
Authors: Fitzpatrick B. G. , Yin G. 
Published: March 2021

Abstract
We examine the large sample behavior of Bayesian posterior distributions in a nonlinear regression model for statistical inference in distributed parameter identification. Under suitable conditions, we prove the consistency of the parameter identification algorithm via Bayesian approach. We then derive large deviations results for independent, identically distributed error models. The large deviations ascertain the rate of convergence. We show that the convergence mentioned above is exponentially fast. That is, there exists a nonnegative function I defined on the parameter set such that πn(dq) ∼ exp(−nI(q))dp for almost all ω, where πn is the conditional distribution of the parameter, given the observations.
Moderate- and High-Intensity Inspiratory Muscle Training Equally Improves Inspiratory Muscle Strength and Endurance—A Double-Blind Randomized Controlled Trial
Authors: Rehder-Santos Patricia , Abreu Raphael M. , Signini Étore De F. , da Silva Claudio D. , Sakaguchi Camila A. , Dato Carla C. , Catai Aparecida M. 
Published: March 2021

Background and Objective: Inspiratory muscle training (IMT) produced outstanding results in the physical performance of active subjects; however, little is known about the best training intensity for this population. The objective was to investigate the impact of an IMT of high intensity, using the critical inspiratory pressure (CIP), on inspiratory muscle strength (IMS), inspiratory muscle endurance (IME), peak power, and oxygen uptake of recreational cyclists; and to compare these results with moderate-intensity IMT (60% of maximal inspiratory pressure [MIP]). Methods: Thirty apparently healthy male recreational cyclists, 20–40 years old, underwent 11 weeks of IMT (3 times per week; 55 min per session). Participants were randomized into 3 groups: sham group (6 cmH2O; n = 8); 60% MIP (MIP60; n = 10) and CIP (n = 12). All participants performed the IMS test and incremental IME test at the first, fifth, ninth, and 13th weeks of the experimental protocol. Cardiopulmonary exercise testing was performed on an electromagnetic braking cycle ergometer pre-IMT and post-IMT. Data were analyzed using a 2-way repeated measures ANOVA (group and period factors). Results: IMS increased in CIP and MIP60 groups at the ninth and 13th weeks compared with the sham group (P < .001; β = 0.99). Regarding IME, there was an interaction between the CIP and MIP60 groups in all periods, except in the initial evaluation (P < .001; β = 1.00). Peak power (in watts) increased after IMT in CIP and MIP60 groups (P = .01; β = 0.67). Absolute oxygen uptake did not increase after IMT (P = .49; β = 0.05). Relative oxygen uptake to lean mass values did not change significantly (P = .48; β = 0.05). Conclusion: High-intensity IMT is beneficial on IMS, IME, and peak power, but does not provide additional gain to moderate intensity in recreational cyclists.
Reallocating Time From Sedentary Behavior to Physical Activity in Patients With Peripheral Artery Disease: Analyzing the Effects on Walking Capacity Using Compositional Data Analysis
Authors: Germano-Soares Antonio Henrique , Tassitano Rafael M. , Farah Breno Quintela , Andrade-Lima Aluísio , Correia Marília de Almeida , Gába Aleš , Štefelová Nikola , Puech-Leao Pedro , Wolosker Nelson , Cucato Gabriel Grizzo , Ritti-Dias Raphael Mendes 
Published: March 2021

Background: To examine the associations between physical activity (PA) and sedentary behavior (SB) with walking capacity and the effects of reallocating time from SB to PA in patients with symptomatic peripheral artery disease (PAD) using compositional data analysis.Methods: This cross-sectional study included 178 patients (34% females, mean age = 66 [9] y, body mass index = 27.8 [5.0] kg/m2, and ankle-brachial index = 0.60 [0.18]). Walking capacity was assessed as the total walking distance (TWD) achieved in a 6-minute walk test, while SB, light-intensity PA, and moderate to vigorous-intensity PA (MVPA) were measured by a triaxial accelerometer and conceptualized as a time-use composition. Associations between time reallocation among wake-time behaviors and TWD were determined using compositional isotemporal substitution models.Results: A positive association of MVPA with TWD (relative to remaining behaviors) was found in men (βilr = 66.9, SE = 21.4,P = .003) and women (βilr = 56.5, SE = 19.8;P = .005). Reallocating 30 minutes per week from SB to MVPA was associated with higher TWD in men (6.7 m; 95% confidence interval, 2.6–10.9 m) and women (4.5 m; 95% confidence interval, 1.5–7.5 m).Conclusions: The findings highlight, using a compositional approach, the beneficial and independent association of MVPA with walking capacity in patients with symptomatic PAD, whereas SB and light-intensity PA were not associated.
Methylation status of vault RNA 2-1 promoter is a predictor of glycemic response to glucagon-like peptide-1 analog therapy in type 2 diabetes mellitus
Authors: Lin Chia-Hung , Lee Yun-Shien , Huang Yu-Yao , Tsai Chi-Neu 
Published: March 2021

IntroductionTherapeutic efficiency of glucagon-like peptide-1 (GLP-1) analog is about 50%–70% in type 2 diabetes mellitus (T2DM). Discovery of potential genetic biomarkers for prediction of treatment efficiency of GLP-1 analog before therapy is still necessary. We assess whether DNA methylation was associated with glycemic response to GLP-1 analog therapy in patients with poorly controlled T2DM.Research design and methodsGenomic DNA was extracted from the peripheral blood of training (n=10) and validation (n=128) groups of patients with T2DM receiving GLP-1 analogs. DNA methylome was analyzed using Infinium Human Methylation EPIC Bead Chip in the training group. The candidate genes were examined using a pyrosequencing platform in the validation group. The association between DNA methylation status and glycemic response to GLP-1 was analyzed in these patients.ResultsThe most differential methylation region between those with a good (responsive) and poor (unresponsive) glycemic response to GLP-1 analog therapy was located on chromosome 5q31.1 (135415693 to 135416613), the promoter ofVTRNA2-1in the training group. The methylation status of theVTRNA2-1promoter was examined in the validation group via pyrosequencing reaction, and the hypomethylation ofVTRNA2-1(<40% methylation) was significantly associated with poor glycemic response to GLP-1 treatment (OR 2.757, 95% CI 1.240 to 6.130, p=0.011). Since theVTRNA2-1promoter region was previously reported maternal imprinting extended to the adjacent centromeric CCCTC-binding factor site that contained an A/C polymorphism (rs2346018), which was associated with methylation density ofVTRNA2-1, this A/C polymorphism was also integrated to analyze association with glycemic response to GLP-1 analog therapy. In patients with the A allele of rs2346018 and hypomethylation (<40%) on theVTRNA2-1promoter, the OR increased to 4.048 (95% CI 1.438 to 11.389, p=0.007).ConclusionsThe glycemic response to GLP-1 analog treatment is associated with the methylation status of theVTRNA2-1promoter and polymorphism of rs2346018.
In-Motion-App for remote General Movement Assessment: a multi-site observational study
Authors: Adde Lars , Brown Annemette , van den Broeck Christine , DeCoen Kris , Eriksen Beate Horsberg , Fjørtoft Toril , Groos Daniel , Ihlen Espen Alexander F , Osland Siril , Pascal Aurelie , Paulsen Henriette , Skog Ole Morten , Sivertsen Wiebke , Støen Ragnhild 
Published: March 2021

ObjectivesTo determine whether videos taken by parents of their infants’ spontaneous movements were in accordance with required standards in the In-Motion-App, and whether the videos could be remotely scored by a trained General Movement Assessment (GMA) observer. Additionally, to assess the feasibility of using home-based video recordings for automated tracking of spontaneous movements, and to examine parents’ perceptions and experiences of taking videos in their homes.DesignThe study was a multi-centre prospective observational study.SettingParents/families of high-risk infants in tertiary care follow-up programmes in Norway, Denmark and Belgium.MethodsParents/families were asked to video record their baby in accordance with the In-Motion standards which were based on published GMA criteria and criteria covering lighting and stability of smartphone. Videos were evaluated as GMA ‘scorable’ or ‘non-scorable’ based on predefined criteria. The accuracy of a 7-point body tracker software was compared with manually annotated body key points. Parents were surveyed about the In-Motion-App information and clarity.ParticipantsThe sample comprised 86 parents/families of high-risk infants.ResultsThe 86 parent/families returned 130 videos, and 121 (96%) of them were in accordance with the requirements for GMA assessment. The 7-point body tracker software detected more than 80% of body key point positions correctly. Most families found the instructions for filming their baby easy to follow, and more than 90% reported that they did not become more worried about their child’s development through using the instructions.ConclusionsThis study reveals that a short instructional video enabled parents to video record their infant’s spontaneous movements in compliance with the standards required for remote GMA. Further, an accurate automated body point software detecting infant body landmarks in smartphone videos will facilitate clinical and research use soon. Home-based video recordings could be performed without worrying parents about their child’s development.Trials registration numberNCT03409978.
Patients’ and healthcare professionals’ beliefs, perceptions and needs towards chronic kidney disease self-management in China: a qualitative study
Authors: Shen Hongxia , van der Kleij Rianne M J J , van der Boog Paul J M , Wang Wenjiao , Song Xiaoyue , Li Zhengyan , Lou Xiaoping , Chavannes Niels 
Published: March 2021

ObjectivesTo support the adaptation and translation of an evidence-based chronic kidney disease (CKD) self-management intervention to the Chinese context, we examined the beliefs, perceptions and needs of Chinese patients with CKD and healthcare professionals (HCPs) towards CKD self-management.DesignA basic interpretive, cross-sectional qualitative study comprising semistructured interviews and observations.SettingOne major tertiary referral hospital in Henan province, China.Participants11 adults with a diagnosis of CKD with CKD stages G1–G5 and 10 HCPs who worked in the Department of Nephrology.ResultsFour themes emerged: (1) CKD illness perceptions, (2) understanding of and motivation towards CKD self-management, (3) current CKD practice and (4) barriers, (anticipated) facilitators and needs towards CKD self-management. Most patients and HCPs solely mentioned medical management of CKD, and self-management was largely unknown or misinterpreted as adherence to medical treatment. Also, the majority of patients only mentioned performing disease-specific acts of control and not, for instance, behaviour for coping with emotional problems. A paternalistic patient–HCP relationship was often present. Finally, the barriers, facilitators and needs towards CKD self-management were frequently related to knowledge and environmental context and resources.ConclusionsThe limited understanding of CKD self-management, as observed, underlines the need for educational efforts on the use and benefits of self-management before intervention implementation. Also, specific characteristics and needs within the Chinese context need to guide the development or tailoring of CKD self-management interventions. Emphasis should be placed on role management and emotional coping skills, while self-management components should be tailored by addressing the existing paternalistic patient–HCP relationship. The use of electronic health innovations can be an essential facilitator for implementation.