bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Model-Based Decomposition of Powertrain System Design
Authors: Michelena Nestor F. , Papalambros Panos Y.
Published: March 2021

Optimal design of large engineering systems modeled as nonlinear programming problems remains a challenge because increased size reduces reliability and speed of numerical optimization algorithms. Decomposition of the original model into smaller coordinated submodels is desirable or even necessary. The article presents a methodology for optimal model-based decomposition of design problems, whether or not initially cast as optimization models. The overall model is represented by a hypergraph and is optimally partitioned into weakly-connected subgraphs that satisfy partitioning constraints. The formulation is robust enough to account for computational demands and resources, and the strength of interdependencies between the simulation modules contained in the model. This decomposition methodology is applied to a vehicle powertrain system design model comprising of engine, torque converter, transmission, and wheel-tire assembly, with 87 design relations and 119 design and state variables.
The Use of Activity-Based Costing, Uncertainty, and Disassembly Action Charts in Demanufacture Cost Assessments
Authors: Bras Bert , Emblemsvåg Jan
Published: March 2021

In this paper, the development of an Activity-based Cost (ABC) model is presented for use in design for demanufacture under the presence of uncertainty. Demanufacture is defined as the process opposite to manufacturing involved in recycling materials and product components after a product has been taken back by a company. The crux in developing an ABC model is to identify the activities that will be present in the demanufacturing process of a product, and afterwards assign reliable cost drivers and associated consumption intensities to the activities. Uncertainty distributions are assigned to the numbers used in the calculations, representing the inherent uncertainty in the model. The effect of the uncertainty on the cost and model behavior are found by employing a numerical simulation technique — the Monte Carlo simulation technique. The additional use of disassembly action charts allows the influence of the uncertainty to be traced through the cost model to specific demanufacture process and product design parameters.
Multiobjective Optimization of a Leg Mechanism With Various Spring Configurations for Force Reduction
Authors: Shieh W. B. , Tsai L.-W. , Azarm S. , Tits A. L.
Published: March 2021

In this paper, the design of a two degree-of-freedom leg mechanism is accomplished by a two-stage optimization process. In the first stage, leg dimensions are optimized with respect to three design objectives: minimize (i) peak crank torque for an entire walking cycle, (ii) leg size, and (iii) vertical actuating force. Following the optimization of leg dimensions, in the second stage, spring elements with various placement configurations are considered for further reduction of the actuating force and crank torque. Several tradeoff solutions are obtained and a comparison between various spring configurations is made. It is shown that the inclusion of spring elements can significantly reduce the actuating force and crank torque.
Fatigue Strength of Metal / FRP Adhesive Joints Under Low Temperature
Authors: Hattori Toshio , Iwasa Masaaki
Published: March 2021

Fiber reinforced plastics (FRP) have the excellent thermal isolation characteristics, and are used for for cryogenic structures such as super conducting magnets. Generally these FRP materials are connected with metal structures using adhesive joint, as these FRP materials loose strength by the existence of bolt holes. In this metal/FRP adhesive joints high thermal residual stresses occur under cryogenic temperatures as the thermal expansion coefficients of both materials differ large. So, improvement of strength evaluation method of these bi-material adhesive joints under low temperature become indispensable to develop high-reliability super conducting magnet systems such as form Magnetic Levitation Liner Motor Car. In this paper we present a new fatigue strength evaluation method under high thermal residual stresses using following two stress singularity parameters K and λ at bonding edges.

τ ( r ) = K / rλ

Heat τ(r) is stress (MPa), r is the distance (mm) from the singular point (bonding edge), K is the intensity of stress singularity and λ is the order of stress singularity.

And this evaluation method is applied to Stainless-steel/Al2O3 FRP adhesive joint models.
A Virtual Engineering System for Electromechanical Products
Authors: Narikawa N. , Kuroiwa T. , Fujinuma T. , Sekimoto S.
Published: March 2021

This paper gives an overview of virtual enginecring (VE) system for electromechanical products. To reduce design costs and to manufacture high-quality products, it is well known that concurrent engineering (CE) is very efficient approach. Three-dimensional (3D) CAD system and engineering database system are essential components of CE. VE system is an environment to realize CE. By creating 3D models in a computer and performing some simulations such as mechanical, electronic, software simulation and integrated simulations, it is possible to estimate functions, assemblability, manufacturability and so on, without making prototype models. In this paper, we outline the VE system and mainly discuss the engineering database system which makes an important role of the VE system. This system is developed by applying the object oriented technology.
Introducing the Industrial Product Realization Process Into Mechanical Engineering Design Education
Authors: Browne Vance D.
Published: March 2021

The process by which new products are brought to market — the product realization process, or PRP — can be introduced in engineering design education.

In industry, the PRP has been evolving to concurrent engineering and product teams. The PRP includes components such as concept generation, analysis, manufacturing process development and customer interaction. Also, it involves the sequencing of the components and their connections which includes teamwork, project planning, meetings, reports and presentations.

A capstone senior engineering project, along with classroom lectures and presentations can be structured to provide knowledge and experience to the students in many of the PRP components and the connections. This paper will give an overview of the PRP and a project/lecture structure at the author’s university. The instructor recently joined the academic ranks after years in industry with responsibility for directing product development and R&D and for leading product development teams.
Elastic Robot Arms With Variable Length: Part II — Robust Control of Elastic Vibrations
Authors: Söffker Dirk
Published: March 2021

In the last years modeling, simulation, and control of flexibel structures have made an essential progress, especially stimulated by the requirements of space operations. For this working field, flexible lightweight robots can enhance the work space of space robots very well, if the length of the robot arm is variable.

Contributions in the corresponding literature mostly consider models of special configurations and perform simple approximations or even assume linear models to describe the elastic motions of the robot. However, especially in the case of lightweight robots undergoing large reference motion, its nonlinear dynamic behaviour should be modeled as exact as possible.

The mechanical system should be controlled to improve its dynamical behaviour. Unfortunately, it is not possible to measure the position of the endeffector. The only measurements that can be done are that of the strains of the beam. The control input should be the velocity (translational and rotational) transmitted to the base of the beam. This includes a correction of the actual path planning values as a kinematical control.

Here the specified task is solved in two parts:

Firstly, the variable length, the geometric nonlinear beam behaviour and the large reference motion of the driven joint are taken into consideration with a systematic modeling approach in (Söffker, 1995b; Söffker, 1995c).

Nonlinear control approaches can often be used only for special classes of problems assumptions have to be made, which cannot be generally fulfilled in practice. Here a new controller is developed which is realizable for on-line applications with the mentioned restrictions. Therefore, in a second part the mechanical plant will be controlled by a new observer-based dynamic compensation scheme.

Based on a linear time-invariant model, nonlinear effects and unmodeled dynamics are estimated in a first step by an Proportinal-Integral (PI) observer scheme, whereby the nonlinearities and the effects of the non-considered time-varying parameters etc. are assumed as external disturbances.

The used PI-observer (Söffker, 1995a) estimates the states of the system and the external disturbances under some weak assumptions.

Using this informations about the external disturbances to the nominal time-invariant system, the task of an extended regulator scheme is to compensate these effects in a second step. Because of the structure of the given mechanical system, usual static disturbance compensation schemes are not useful. Therefore a new dynamic approach is developed, which uses the estimations of the extended observer. The developed method does not depend on the structure of the physical problem and can be also used more generally. This is mainly due to the robustness of the observer-based dynamic compensation scheme.

Two examples of a very flexible spatial telescopic robot arm demonstrate the effects of disturbances compensation and control of the elastic vibrations induced by the initial conditions and the reference motion.
A New Aeroelastic Oscillator, Theory and Experiments
Authors: van der Burgh A. H. P. , Haaker T. I. , van Oudheusden B.-W.
Published: March 2021

This paper reviews recent work on the development of a new type of an aeroelastic oscillator with one degree of freedom in a uniform windfield. The typical characteristics of the oscillator are the low frequency (less than 1 Hz) allowing application of a quasi-steady modeling and a combined translational and rotational motion in cross-flow.

The oscillator is developed for the study of galloping oscillations in a wind tunnel. The model equation is validated by comparing its solutions with the experimental results. In the quasi-steady modeling for the dynamic behaviour use is made of the numerical values of aerodynamic coefficients obtained from wind tunnel measurements on the oscillator in a static position. Particularly the dependence of limit amplitudes on the flow velocity, obtained from the analysis of the model equations are compared with the ones obtained from experiments.
Numerical and Experimental Studies of the Vibration and Acoustic Behaviors of MRI Gradient Tube
Authors: Ling J. X. , Amor William , DeMeester Gordon
Published: March 2021

This paper comes from a realistic engineering project — an optimal design of the gradient system for a NMR machine for medical imaging. A three-dimensional finite element model was developed to study the vibration and acoustic characteristics of the gradient tube using ANSYS, a commercial Finite Element Analysis code. 3-D 8-node structural solid elements, 3-D 8-node layered structural elements and 3-D 8-node acoustic elements are used in the model. Linear transient analysis (dealing with the dynamic response of the composite cylindrical shell under periodic loading), as well as the coupling dynamic and acoustic analysis have been conducted. The linear transient analysis results in the displacement and acceleration time histories of the composite tube. The coupling analysis predicts the air motion (the sound wave) on the patient side of the tube. To verify the numerical results, some vibration and acoustic measurements are also carried out. All the numerical results are in good agreement with the experimental data and provide valuable information for evolving the gradient design. Similar FEA models have been developed for the alterative design versions. As a result, an optimal design of the gradient system has been achieved and the acoustic noise level of the latest design reduced by 12–15 dBA compared to the previous designs under similar operating conditions.
Wavelet Analysis of Stick-Slip in an Oscillator With Dry Friction
Authors: Liang J. W. , Feeny B. F.
Published: March 2021

The dynamic behavior of the transition between slipping and sticking motions of a mass-spring system with dry friction is studied numerically and experimentally. Three mathematical models of dry friction are incorporated in the forced oscillator’s equation of motion. The wavelet transform is used to analyze response signals for both high and low frequency contents. For the simulated dynamical response, the wavelet transform can efficiently depict the transition characteristics in the time/frequency domain. The signatures observed in wavelet contour plot are compared to experimental results to evaluate the mathematical friction models. The wavelet transform can also be used to detect the dynamics of the sensor. The low-frequency experimental friction behavior is somewhat like the Coulomb friction model and its smooth version.
Analysis of Beam-Like Structures With Displacement-Dependent Friction Forces: Part II — Multi-Degree-of-Freedom Model
Authors: Whiteman Wayne E. , Ferri Aldo A.
Published: March 2021

A multi-mode analysis of a beam-like structure undergoing transverse vibration and subjected to a displacement-dependent friction force is conducted. The level of displacement-dependence is governed by a ramp angle and spring arrangement as discussed in Part I. The system is studied by using harmonic balance as an approximate analytical solution and then by using a time integration method. The damping characteristics of the system are studied in detail. The results qualitatively agree with those obtained using a single-degree-of-freedom analysis of this system reported in Part I. Interesting findings include the appearance of internal resonance peaks when multiple modes are considered. Also, as with the earlier single-degree-of-freedom study, two dynamic response solutions exist at certain parameter values. It is found that the ability to control the amplitude of the response is a function of the frequency range considered. In general, near modal resonance peaks, the amplitude of the response decreases with increasing ramp angle. However, in an “overlapping” region between resonance peaks, the amplitude of the response actually increases with increasing ramp angle. Detailed analysis of the damping characteristics indicate that the dry friction damper is most effective in damping the fundamental mode. The other critical observation is that the damping contribution from the displacement-dependent dry friction damper is “viscous-like” in nature and relatively insensitive to the amplitude of the response. This result suggests that in the case of turbine or compressor blades, this type of damping arrangement may be effective in the suppression of flutter.
A Study of the Effects of Negative Friction-Speed Slope on Brake Squeal
Authors: Yuan Yongbin
Published: March 2021

Brake squeal is caused by friction-induced vibration of brake systems. It may take place due to several possible mechanisms. The inverse variation of friction coefficient with relative sliding speed, also called negative μ-v slope, is one of them. Although it has been demonstrated in many articles that negative μ-v slope can cause unstable vibration for systems with a single degree of freedom (d.o.f.), its effects on multi-d.o.f. brake systems are not yet well understood. Since almost all types of friction materials for automotive brakes exhibit negative μ-v slope under certain conditions, it is important to clarify its role in brake squeal.

The current study incorporates the negative μ-v slope friction law into a Finite element model for disc brake systems. The rotor and pads are modeled by beam elements, and the caliper is represented by a rigid body with two degrees of freedom. The effects of negative μ-v slope on the vibration stability of a brake system are studied along with several parameters including friction level, lining compression modulus, and steelback thickness.
Resonant-Frequency-Distribution of Internal Mass Inferred From Mechanical Impedance Matrices, With Application to Fuzzy Structure Theory
Authors: Pierce Allan D.
Published: March 2021

The partitioning of internal mass among bands of resonant frequencies is addressed for a prototype internal vibrating structure with small damping, attached via an arbitrary number NA of attachment points to an external structure. Insofar as the dynamics of the latter are concerned, the internal structure is adequately described by a frequency-dependent impedance matrix, any given column of which lists the ratios of the 3NA force components induced by one of the attachment points’ velocity components when all of the other velocity components are held to zero. The properties of matrix elements and their frequency dependence are discussed in relation to principles of mechanics, especially the requirements of translational and rotational invariance of the potential energy functions. Among the deductions are that modal masses can be defined with values calculable solely from the impedance matrix measurements, and that the modal masses sum to the total mass of the internal vibrating system.
Analysis of Pulsations and Vibrations in Fluid-Filled Pipe Systems
Authors: de Jong Christ A. F.
Published: March 2021

Pressure pulsations and mechanical vibrations in pipe systems may cause excessive noise and may even lead to damage of piping or machinery. In fluid-filled pipe systems pulsations and vibrations will be strongly coupled. A calculation method has been developed for the simulation of coupled pulsations and vibrations in pipe systems. The analytical method is based upon the transfer matrix method. It describes plane pressure waves in the fluid and extensional, bending and torsional waves in the pipe wall. Fluid pulsations and pipe wall vibrations are coupled at discontinuities (e.g. elbows and T-junctions) and via Poisson contraction of the pipe wall. For a given source description, the model calculates levels of vibration, mode shapes, vibro-acoustic energy flow, etc. The method has been validated experimentally on a test rig consisting of two straight pipes and an elbow. The predicted pulsation and vibration levels agree reasonably well with the measurements.
Optimal Unbalance Response of Continuous Rotors
Authors: Parszewski Zdzislaw A. , Li Dong-Xu
Published: March 2021

Dynamically optimal alignment of multi-bearing rotors has become one of the principal applications of the system dynamics in its configuration or layout parameters, (Parszewski, 1987). Using non-linear bearing effects and the independent parameters provided by their statical indeterminacy, the alignment of multi-bearing rotors has been optimised for least unbalance response. The rotor unbalance was estimated with the complex modal approach, using measured unbalance response. Some computed results and experiments on a four-bearing laboratory installation were presented in (Parszewski and Li, 1989). This present paper expands the analysis and provides an industrial application of the theory to a turbogenerator, operating in a power station. Comparison with the conventional catenary alignment is also given and shearing forces and bending moments on the couplings are revealed for both cases, showing the advantages of the optimal alignment of the rotor as a continuous shaft.
Forced Wave Propagation in Elastic Cables With Small Curvature
Authors: Behbahani-Nejad M. , Perkins N. C.
Published: March 2021

This study presents an investigation of the coupled longitudinal-transverse waves that propagate along an elastic cable. The coupling considered derives from the equilibrium curvature (sag) of the cable. A mathematical model is presented that describes the three-dimensional nonlinear response of a long elastic cable. An asymptotic form of this model is derived for the linear response of cables having small equilibrium curvature. Linear in-plane response is described by coupled longitudinal-transverse partial differential equations of motion, which are comprehensively evaluated herein. The spectral relation governing propagating waves is derived using transform methods. In the spectral relation, three qualitatively distinct frequency regimes exist that are separated by two cut-off frequencies. This relation is employed in deriving a Green’s function which is then used to construct solutions for in-plane response under arbitrarily distributed harmonic excitation. Analysis of forced response reveals the existence of two types of periodic waves which propagate through the cable, one characterizing extension-compressive deformations (rod-type) and the other characterizing transverse deformations (string-type). These waves may propagate or attenuate depending on wave frequency. The propagation and attenuation of both wave types are highlighted through solutions for an infinite cable subjected to a concentrated harmonic excitation source.
A Spectral Element for Acoustic Wave Propagation Through Multi-Layered Media
Authors: Doyle James F. , Bilodeau Brian A.
Published: March 2021

A spectral element is developed for analyzing acoustic wave propagation through multi-layered panels. The elements may be conveniently joined to model complex structures composed of many layers of solids and fluids. The element exactly models the in-plane responses over large domains. Results for the impact of single and double panel systems are presented.
Dynamic Stability Analysis for Multi-Flute End Milling
Authors: Shorr Michael J. , Liang Steven Y.
Published: March 2021

This research discusses the methodology of developing a symbolic closed form solution that describes the dynamic stability of multi-flute end milling. A solution of this nature facilitates machine tool design, machining parameter planning, process monitoring, diagnostics, and control. This study establishes a compliance feedback model that describes the dynamic behavior of regenerative chatter for multi-flute tool-work interaction. The model formulates the machining dynamics based upon the interconnecting relationship of the tool geometry convolution and the machining system compliance. The tool geometry convolution characterizes the cutting forces as a function of the process parameters and the material properties, while two independent vibratory modules, the mill tool and the workpiece, represent the machining system compliance. The compliance feedback model allows the development of a corresponding characteristic equation. By investigating the roots of the characteristic equation, this research symbolically expresses the stability of the system as a function of the cutting parameters, the tool geometry, the workpiece geometry, and the vibrational characteristics of the machine tool. Machining experimentation examining the fidelity of the regenerative charter model is discussed. The dynamic cutting forces, cutting vibration, and surface finish of the machining process confirm the validity of the analytical prediction.
Identification of Inertial Properties for Resiliently Supported Mechanical System
Authors: Nakamura Masanobu , Sawanobori Takeshi , Nagamatsu Akio
Published: March 2021

Parameters such as the principal moment of inertia, principal axis of inertia, and the location of center of mass are very important and necessary for simulation of the dynamic properties for design of a mechanical system (Kunieda, 1984, Taniguchi, 1976). Therefore in this paper, we examine an approach for experimental identification of the characteristic matrices using the modal parameters to obtain the inertia! properties of mechanical system. And then influences of the measurement error of Frequency Response Function (FRF) on identified values are investigated in detail.
Transient Response Analysis of Compressor-Piping Coupled System in Air Conditioning Units
Authors: Sawanobori Takeshi , Nakamura Masanobu , Nagamatsu Akio , Okamoto Jyoji
Published: March 2021

In the present paper authors wish to propose a method for the modeling and formulation to improve the design process of piping lines in the air conditioning unit. The essential part of the proposed method is to combine three identification principles : (1) the kinematical and kinetic analysis of compressor for obtaining the exciting forces and torque transmitted to piping lines; (2) the derivation method of physical matrices of piping lines with the finite elements method; (3) the experimental identification method of physical matrices of the compressor and accessories on resilient supporting elements using modal parameters obtained by modal testing.

The proposed method simplifies a procedure for formulation process of the compressor-piping coupled system and estimates accurately dynamic responses of piping lines. Validity of the proposed method is corroborated with experimental results.
Electromagnetically Generated Acoustic Noise in DC Machines
Authors: Hwang Sangmoon , Lieu Dennis K.
Published: March 2021

Acoustic noise of generated in DC motors is difficult to predict, and its exact mechanism is unclear. It is a common observation that brushless DC motors with rare earth magnets are often acoustically inferior to motors of equivalent output built with conventional magnets. In this paper, the acoustic noise of electromagnetic origin is investigated using a magnetic frame which emulates a DC motor. The driving electromagnetic force is calculated using finite element analysis and the resulting vibration and acoustic noise is measured. Acoustic noise of purely electromagnetic origin was also measured from a DC brushless motor to confirm the results of the magnetic frame. The results of the study show that the mechanism of noise generation can be a quasi-static response of a stator not only at the fundamental frequency but also at higher harmonic frequencies of alternating switched DC excitation of motor phases. Noise generation is significantly aggravated when some of those harmonics match the resonant frequencies of the stator. Eddy current flow within the magnets due to the time varying electromagnetic field act as a shorted transformer secondary winding, and results in a reduction of the electrical phase impedance. This reduced impedance results in a faster rise time with a sharper current shape during transients, and increased current magnitude during steady state, thus making the motor noisier.
Consideration of Both Extensional and Shear Strain of Core Material in Modal Property Estimation of Sandwich Plates
Authors: Lee Byung-Chan , Kim Kwang-Joon
Published: March 2021

In vibration analysis of sandwich beam/plates, it is often assumed that there occurs shear deformation only, i.e. no extension or compression, in the core viscoelastic layer. Certainly, this assumption may have limitations, for example, with increase of the core thickness or frequency range of vibration. The purpose of this paper is to consider the extentional as well as shear strain of the core for modal parameter estimation of the sandwich plates and to investigate how much error will be caused by neglecting the extension or compression in the core material. Natural frequencies and modal loss factors are estimated for a simply supported square plates under each of the above two assumptions. Nondimensional characteristic equations are formulated and solved for various ratios of the base layer thickness to plate length, core to base layer thickness, and constraining layer to base layer thickness.
Reduction of Vibrations in Complex Structures With Viscoelastic Neutralizers: A Generalized Approach
Authors: de Espíndola J. J. , Bavastri C. A.
Published: March 2021

A general procedure for the optimization of the parameters of dynamic neutralizes is presented. It can be applied to the minimization of the vibration response and sound radiation of linear strutures subjected to excitations in a specified frequency range.

Modal theory and generalized equivalent quantity concept for the neutralizers, introduced by Espíndola and Silva (1992), are applied to a non-linear optimization scheme. The proposed procedure can be applied to relaxed and time invariant structures. It is not dependent on the struture complexity and the degree of discretization adopted.

In such conditions, a significant reduction in computing work is achieved, if compared with the more traditional methods.
Elastic Impedance Tomography
Authors: Nakamura Gen , Uhlmann Gunther
Published: March 2021

As a mathematical model of nondestructive testing for an elastic medium we consider the inverse problem of determining the elastic tensor of the medium from its associated Dirichlet to Neumann map. This is an analogue to the inverse problem of electric impedance tomography which consists in determining the electrical conductivity of a medium from its associated Dirichlet to Neumann map. We give an overview of the recent developments on this area. We also give an application of the results to the inverse scattering problem at a fixed energy for an elastic medium.
An Efficient Approximated Algorithm for Balancing and Order Reduction of Lightly Damped Systems
Authors: Halevi Yoram
Published: March 2021

A method of approximating the controllability gramian, observability gramian and the balancing transformation for lightly damped mechanical systems is presented, the approximation uses the special structure of the system and the fact that the damping is small to reduce the amount of computation considerably. Furthermore, one can avoid the calculation of the entire balancing transformation matrix and calculate only the parts that are required for order reduction. In cases where the reduced order is much smaller than the original that leads to another substantial reduction of computation effort.
Physical Parameter Identification of Laminates Based on Thermal Deformation Measurements
Authors: Konrad Werner , Caesar Bernd
Published: March 2021

High precision structures, as telescope mirrors for space applications, require high thermal stability and structural stiffness combined with low weight. Laminate structures with their special properties can satisfy these stringent requirements.

Model updating and physical parameter identification on the basis of measurements can be applied to optimize such structures or define correction measures w.r.t. manufacturing inaccuracies.

In classic update procedures correction factors are used to improve physical parameters. The definition of correction differences which are suitable for parameters with zero starting values or values changing from positive to negative as it may be the case for the layer orientations of a laminate is presented.

High precision structures require high accurate measuring methods for the test. Thermal deformations can be measured by holographic, interferometric methods with high precision in the μm range. An interferometric contour map can be compared with the nodal point displacements of a Finite Element model by special spline functions called Zernike’s polynomials.

The equations to determine the various design parameters or material properties may not be linear independent, depending on the applied thermal load case. The degree of correlation between the various parameters is investigated. The results are used to optimize the load case selection and to improve error localization methods.

The proposed method is applied to a segment of a high stability spherical mirror plate with real measuring data.
Local Adaptation of Legionella pneumophila within a Hospital Hot Water System Increases Tolerance to Copper
Authors: Bédard Emilie , Trigui Hana , Liang Jeffrey , Doberva Margot , Paranjape Kiran , Lalancette Cindy , Allegra Séverine , Faucher Sebastien P. , Prévost Michèle
Published: March 2021

Legionella pneumophila
is a pathogen indigenous to natural and large building water systems in the bulk and the biofilm phases. The immediate environment within a system can impact the tolerance of
L. pneumophila
to environmental stressors, including copper.
On Global Solvability of Nonlinear Equations with Parameters
Authors: Arutyunov A. V. , Zhukovskiy S. E.
Published: March 2021

We consider smooth mappings acting from one Banach space to another and depending on a parameter belonging to a topological space. Under various regularity assumptions, sufficient conditions for the existence of global and semilocal continuous inverse and implicit functions are obtained. We consider applications of these results to the problem of continuous extension of implicit functions and to the problem of coincidence points of smooth and continuous compact mappings.
Bioinformatics-Based Identification of lncRNA-miRNA-mRNA Network in Dilated Cardiomyopathy and Drug Prediction
Authors: Liu Wei , Cai Jinqiang , Tang Mengjie , Yang QinJing
Published: March 2021

Background. Dilated cardiomyopathy (DCM) is a cardiovascular disease of unknown etiology with progressive aggravation. More and more studies have shown that long noncoding RNAs (lncRNAs) play an essential role in dilated cardiomyopathy formation and development. The mechanism of action of competitive endogenous RNA (ceRNA) networks formed based on the principle that lncRNAs affect mRNAs’ expression level by competitively binding microRNAs (miRNAs) in dilated cardiomyopathy has rarely been reported. Objective. This study is aimed at constructing a lncRNA-miRNA-mRNA ceRNA network by bioinformatics analysis methods, discovering, and validating potential biomarkers of DCM in the ceRNA network and determining possible therapeutic targets from them for drug prediction. Methods. A lncRNA dataset and a mRNA microarray dataset were downloaded from the Gene Expression Omnibus Database (GEO). Gene expression was compared between blood samples from patients with dilated cardiomyopathy and blood samples from normal subjects to identify differential expression of lncRNAs and mRNAs. The lncRNA-miRNA-mRNA network was constructed using bioinformatics tools, and functional and pathway enrichment analysis and protein-protein interactions were performed. The mRNAs in the network and the proteins they encode are then used as targets for predicting drugs. Besides, the expression of lncRNAs in the ceRNA network was validated by real-time quantitative PCR (qRT-PCR) experiments in vitro. Results. The differentially expressed lncRNA-miRNA-mRNA ceRNA network in dilated cardiomyopathy was successfully established. Two differentially overexpressed key lncRNAs were found from the network: AC093817 and AC091062, and qRT-PCR experiments further validated the overexpression of AC093817 and AC091062. The mRNAs in the network and the proteins encoded by the mRNAs were used for drug prediction to get related drugs. Conclusion. This study supports a possible mechanism and drug development of dilated cardiomyopathy, AC093817 and AC091062 being potential biomarkers of dilated cardiomyopathy.
Cardiopulmonary Exercise Testing in Combined Pulmonary Fibrosis and Emphysema
Authors: Westhoff Michael , Litterst Patric , Ewert Ralf
Published: March 2021

Background: Combined pulmonary fibrosis and emphysema (CPFE) is a distinct entity among fibrosing lung diseases with a high risk for lung cancer and pulmonary hypertension (PH). Notably, concomitant PH was identified as a negative prognostic indicator that could help with early diagnosis to provide important information regarding prognosis. Objectives: The current study aimed to determine whether cardiopulmonary exercise testing (CPET) can be helpful in differentiating patients having CPFE with and without PH. Methods: Patients diagnosed with CPFE in 2 German cities (Hemer and Greifswald) over a period of 10 years were included herein. CPET parameters, such as peak oxygen uptake (peak VO2), functional dead space ventilation (VDf/VT), alveolar-arterial oxygen difference (AaDO2), arterial-end-tidal CO2 difference [P(a-ET)CO2] at peak exercise, and the minute ventilation-carbon dioxide production relationship (VE/VCO2 slope), were compared between patients with and without PH. Results: A total of 41 patients with CPET (22 with PH, 19 without PH) were analyzed. Right heart catheterization was performed in 15 of 41 patients without clinically relevant complications. Significant differences in peak VO2 (861 ± 190 vs. 1,397 ± 439 mL), VO2/kg body weight/min (10.8 ± 2.6 vs. 17.4 ± 5.2 mL), peak AaDO2 (72.3 ± 7.3 vs. 46.3 ± 14.2 mm Hg), VE/VCO2 slope (70.1 ± 31.5 vs. 39.6 ± 9.6), and peak P(a-ET)tCO2 (13.9 ± 3.5 vs. 8.1 ± 3.6 mm Hg) were observed between patients with and without PH (p < 0.001). Patients with PH had significantly higher VDf/VT at rest, VT1, and at peak exercise (65.6 ± 16.8% vs. 47.2 ± 11.6%; p < 0.001) than those without PH. A cutoff value of 44 for VE/VCO2 slope had a sensitivity and specificity of 94.7 and 72.7%, while a cutoff value of 11 mm Hg for P(a-ET)CO2 in combination with peak AaDO2 >60 mm Hg had a specificity and sensitivity of 95.5 and 84.2%, respectively. Combining peak AaDO2 >60 mm Hg with peak VO2/body weight/min <16.5 mL/kg/min provided a sensitivity and specificity of 100 and 95.5%, respectively. Conclusion: This study provided initial data on CPET among patients having CPFE with and without PH. CPET can help noninvasively detect PH and identify patients at risk. AaDO2 at peak exercise, VE/VCO2 slope, peak P(a-ET)CO2, and peak VO2 were parameters that had high sensitivity and, when combined, high specificity.
Proposed synchronization circuits connecting wind driven DFIG to the public grid
Authors: Agamy Mohamed Hussein , Ellithy Fahe M. , Nada Adel S.
Published: March 2021

This paper presents a tested proposal scheme to connect a DFIG driven by a wind turbine to the public grid. This scheme was implemented to drive an automatic transfer switch (ATS). Control of the phase sequence, phase difference, and the frequency of the injected power are achieved using these proposed control circuits. These circuits are practically implemented and laboratory tested. The system allows monitoring the rated frequency, synchronization, and fundamental magnitude. Simulation software such as Multi Sim and Proteus are used for system validation and compatibility. The implemented circuits are used for re-scaling the grid voltage to the logic level for real time comparison and calculations. In addition to the feature of data monitoring, the system can also log these data for the system debugging purposes. The system can be considered as a real time control where the measurements and the correction are made in few milliseconds (fractions of the fundamental cycle). The lower cost control circuits are implemented using an Arduino kit in addition to a discrete digital component. The simulation and experimental results are in satisfactory agreement showing the most salient features of this system.
Augmented robust T-S fuzzy control based PMSG wind turbine improved with H∞ performance
Authors: Tidjani Naoual , Guessoum Abderrezak
Published: March 2021

In this paper, an improved augmented Takagi-Sugeno fuzzy control design applied to the system of converting wind turbine energy was proposed. The wind generator used is based on a permanent magnet synchronous wind power generator (PMSG) under varying operation of the wind speed. The proposed T-S fuzzy control strategy aims to maximize wind energy in low wind speed. A part of our contribution lies in the limitation of the power output of the wind generator in high wind speed. Through the concept of the virtual desired variables, the design of the output tracking controller is achieved. In light of this concept, the developed T-S fuzzy control was designed via parallel-distributed compensation (PDC) approach with H∞ performance.

Sufficient conditions for the stability of the closed-loop system affected by external disturbances are proved from Lyapunov’s direct method and the feedback gains of the controller strategy are determined by linear matrix inequalities (LMIs) tools. Another contribution is in showing the robustness of the Takagi-Sugeno based control strategy, with a focus on a set of system parameters with model uncertainties. The simulation results show the high performance of the proposed controller strategy for a 5MW (PMSG) obtained through simulation.
A robust nonlinear control strategy of a PV System connected to the three-phase grid based on backstepping and PSO technique
Authors: Zouga Salma , Benchagra Mohamed , Ailane Abdallah
Published: March 2021

This article presents a robust non-linear control technique of the three-phase photovoltaic system. The structure chosen for this PV system is that of two power converters and DC voltage intermediate bus. The two power converters are: the DC-DC converter and the three-phase inverter, which requires two main controllers. These controllers have three main objectives. The first objective is to impose the PV voltage generated by the photovoltaic panel, in order to follow a maximum reference voltage provided by the MPPT block. The second one is to maintain the DC link voltage to a constant value, in order to optimize the transfer of energy between the two power converters. The last objective is to inject a three-phase sinusoidal current into the grid, while respecting a unit power factor. With the intention to achieve these three objectives, we designed cascading nonlinear controllers by using the technique of non-linear backstepping control in the synthesis of these two controllers, based on the Lyapunov function, with regard to maximise the PVG output voltage, in order to have a unitary power factor at the grid side. In order to regulate DC-link voltage, we developed an integral proportional controller (PI) with parameters that are optimized by the Particle Swarm Optimization (PSO) method. The robustness of the controller designed approach is tested by a simulation in MATLAB/Simulink software, that improves the performances of each controller whatever conditions of climate.
A new multilevel inverter topology based on switched-capacitor technique
Authors: Kakar Saifullah , Ayob S. M. , Bin Arif M. Saad , Nordin N.M. , Daud Z. , Ayop R.
Published: March 2021

This paper presents a new multilevel inverter based on the switched-capacitor technique. The topology aims for renewable energy and fuel cell applications that demand high magnitude output ac voltage. This configuration of the inverter can produce a total of thirteen voltage levels using a single DC source. The topology features voltage boosting with a triple gain of the input voltage source without utilizing a boost DC-DC converter. Furthermore, the voltages of the capacitors are self-balanced at any desired voltage level during each cycle. Therefore, auxiliary circuits are no longer needed. A comparative study of the presented inverter with the classical topologies and recently introduced topologies has been done in power switches, driver circuits, blocking voltage of the switches, and boosting the input voltage. A simple fundamental switching scheme is applied to the proposed topology to validate the viability of the topology.
Attracting new users or business as usual? A case study of converting academic subscription-based journals to open access
Authors: Wenaas Lars
Published: March 2021

This paper studies a selection of 11 Norwegian journals in the humanities and social sciences and their conversion from subscription to open access, a move heavily incentivized by governmental mandates and open access policies. By investigating the journals’ visiting logs in the period 2014–2019, the study finds that a conversion to open access induces higher visiting numbers; all journals in the study had a significant increase, which can be attributed to the conversion. Converting a journal had no spillover in terms of increased visits to previously published articles still behind the paywall in the same journals. Visits from previously subscribing Norwegian higher education institutions did not account for the increase in visits, indicating that the increase must be accounted for by visitors from other sectors. The results could be relevant for policymakers concerning the effects of strict policies targeting economically vulnerable national journals, and could further inform journal owners and editors on the effects of converting to open access.
Five Conducts (Wu Xing 五行) and the Grounding of Virtue
Authors: Perkins Franklin
Published: March 2021

There is now a general consensus that Xunzi’s criticism of Zisi and Mengzi for advocating wu Xing 五行is explained by the excavated text known as Five Conducts (Wu xing), but the five conducts play no significant role in the Mengzi. This article aims to determine more precisely what the Mengzi and Wu xing have in common, while also making sense of the ways in which they diverge. The first part of the article analyzes the distinction between goodness and de 德. The second part examines how the various forms of correct behavior are linked to the internal, pointing out the similarities and differences from Mengzi’s approach.
Beyond gender equality? Anti-gender campaigns and the erosion of human rights and democracy
Authors: Sosa Lorena
Published: March 2021

Although resistance to the incorporation of ‘gender’ in human rights law and policies is not new, since 2013 anti-gender campaigns have articulated as movements and increased their visibility. More recently, the transnational dimension of the anti-gender offensive has become visible as a challenge to human rights standards, including the anti-violence against women project, and a process of democratic erosion. In this column, I make a short overview of this social and political phenomenon and describe how these anti-gender campaigns have entered the human rights systems and their discourse has shifted from religious justifications towards legal ones. I conclude with general suggestions to strengthen the resilience of the human rights systems to these processes.
Post-anticoagulant D-dimer is a highly prognostic biomarker of COVID-19 mortality
Authors: Song Xiaoyu , Ji Jiayi , Reva Boris , Joshi Himanshu , Calinawan Anna Pamela , Mazumdar Madhu , Wisnivesky Juan P. , Taioli Emanuela , Wang Pei , Veluswamy Rajwanth R.
Published: March 2021

Clinical biomarkers that accurately predict mortality are needed for the effective management of patients with severe coronavirus disease 2019 (COVID-19) illness. In this study, we determine whether changes in D-dimer levels after anticoagulation are independently predictive of in-hospital mortality.

Adult patients hospitalised for severe COVID-19 who received therapeutic anticoagulation for thromboprophylaxis were identified from a large COVID-19 database of the Mount Sinai Health System in New York City (NY, USA). We studied the ability of post-anticoagulant D-dimer levels to predict in-hospital mortality, while taking into consideration 65 other clinically important covariates including patient demographics, comorbidities, vital signs and several laboratory tests.

1835 adult patients with PCR-confirmed COVID-19 who received therapeutic anticoagulation during hospitalisation were included. Overall, 26% of patients died in the hospital. Significantly different in-hospital mortality rates were observed in patient groups based on mean D-dimer levels and trend following anticoagulation: 49% for the high mean-increase trend group; 27% for the high-decrease group; 21% for the low-increase group; and 9% for the low-decrease group (p<0.001). Using penalised logistic regression models to simultaneously analyse 67 clinical variables, the high increase (adjusted odds ratios (OR
adj
): 6.58, 95% CI 3.81�11.16), low increase (OR
adj
: 4.06, 95% CI 2.23�7.38) and high decrease (OR
adj
: 2.37; 95% CI 1.37�4.09) D-dimer groups (reference: low decrease group) had the highest odds for in-hospital mortality among all clinical features.

Changes in D-dimer levels and trend following anticoagulation are highly predictive of in-hospital mortality and may help guide resource allocation and future studies of emerging treatments for severe COVID-19.