Identification of the Fractional Zener Model Parameters for a Viscoelastic Material over a Wide Range of Frequencies and Temperatures

The paper presents an analysis of the rheological properties of a selected viscoelastic material, which is dedicated to the reduction of vibrations in structures subjected to dynamic loads. A four-parameter, fractional Zener model was used to describe the dynamic behavior of the tested material. The model parameters were identified on the basis of laboratory tests performed at different temperatures and for different vibration frequencies. After proving that the material is thermoreologically simple, the so-called master curves were created using a horizontal shift factor. The Williams–Landel–Ferry formula was applied to create graphs of the master curves, the constants of which were determined for the selected temperature. The resulting storage and loss module functions spanned several decades in the frequency domain. The parameters of the fractional Zener model were identified by fitting the entire range of the master curves with the gradientless method (i.e., Particle Swarm Optimization), consisting in searching for the best-fitted solution in a set of feasible solutions. The parametric analysis of the obtained solutions allowed for the formulation of conclusions regarding the effectiveness of the applied rheological model.

STATIC AND KINEMATIC ANALYSIS OF A PLANAR REGULAR BEAM TRUSS WITH A DOUBLE LATTICE

Предлагается схема статически определимой регулярной балочной фермы решетчатого вида. Обнаружен и исследован случай кинематического вырождения конструкции от числа панелей. Для сосредоточенной и распределенной по нижнему поясу нагрузок методом индукции с привлечением системы символьной математики выводится зависимость прогиба фермы от числа ее панелей. Прогиб вычисляется по формуле Максвелла-Мора. Полученная зависимость имеет вид полинома по числу панелей с переменными, зависящими от четности числа панелей. Получена также формула зависимости величины горизонтального сдвига подвижной опоры. A scheme of a statically determinate regular girder truss of a lattice type is proposed. The case of kinematic degeneration of the structure from the number of panels is discovered and investigated. For concentrated and distributed loads over the lower belt, the dependence of the deflection of the truss on the number of its panels is derived by induction with the involvement of a system of symbolic mathematics. The deflection is calculated using the Maxwell - Mohr formula. The resulting dependence has the form of a polynomial in the number of panels with variables depending on the parity of the number of panels. A formula for the dependence of the magnitude of the horizontal shift of the movable support is also obtained.

The Dimethyl Fumarate Experience: A Handy Drug With Broad Clinical Utility

Objectives: The aim of this study was to characterize multiple sclerosis (MS) patients exposed to dimethyl fumarate (DMF) and to evaluate the predictors of therapeutic response. In addition, the study offers a picture of how DMF use has changed over the past few years in naive or switcher patients.Methods: In this observational monocentric study, we examined the prescription flow of DMF in MS patients categorized as naive or switchers (for safety/tolerability, ineffectiveness, and de-escalation strategy) from 2015 to 2019. Clinical and magnetic resonance imaging data of DMF-treated patients were analyzed, and NEDA-3 status at 24 months was evaluated by the three assessment components (absence of clinical relapses, no Expanded Disability Status Scale progression, no radiological activity). Determinants of therapeutic response were also evaluated using regression analysis.Results: The sample included 595 MS patients exposed to DMF categorized as naive (158; 26.5%) and switchers for reasons of safety/tolerability (198; 33.3%), inefficacy (175; 29.4%), and de-escalation strategy (64; 10.8%). A 15% increase in DMF use in naive and horizontal shift groups was observed in the last 3 years of observation, whereas there was a drop, with prescription passed from ~20% to <5%, as an exit strategy from second-line therapies. NEDA-3 status was calculated for 340 patients after 24 months of DMF treatment and achieved in 188 (55.3%) of these. Analyzing the predictors of DMF response, we observed that lower annualized relapse rate (ARR) in 2 years pretreatment [hazard ratio (HR) = 0.49, p = 0.001] and being naive patients (HR = 1.38, p = 0.035) were associated with achievement of NEDA-3. Analogously, ARR in 2 years pretreatment affected the NEDA-3 achievement at 24 months in patients of the de-escalation group (HR = 0.07, p = 0.041), also indicating an effect related to the DMF initiation within 3 months (HR = 1.24, p = 0.029).Conclusion: Our findings confirm DMF as a handy drug with broad clinical utility, with greater benefits for naive patients and horizontal switchers. Additionally, an increase in the flow of DMF prescriptions in these two groups of patients was also observed in our cohort.

API Equation Design Limits Plot for Ellipse and Circle of Plasticity

Summary In this paper we present a methodology to superimpose the American Petroleum Institute (API) uniaxial and triaxial limits on tubular design limits plots (API TR 5C3 2018). Complications caused by a recent change of axis are resolved, producing a practical design limits plot that avoids the horizontal shift of the API vertical limits, which is currently the industry standard. The commonly used slanted ellipse is compared against an adaptation of the circle of plasticity in the form of a horizontal ellipse, showing the convenience of this last one with examples. After the current official collapse formulation was made part of the main body of standard API TR 5C3 (2018), the horizontal axis on the standard industry well tubular design limits plot changed. The present study evaluates this redefinition of the horizontal axis. One consequence of this modification is a difficulty plotting the API tension and compression limits. The API horizontal limits (uniaxial burst and collapse) are found to be independent of load situation, whereas the API vertical design limits (uniaxial tension and compression) are dependent on inside and outside tubular pressures. The approaches used by commercial software and industry publications to solve this challenge are reviewed. A new design methodology is developed to link API uniaxial limits to the triaxial theory. One main objective of the study is to establish a mathematical relationship between API tubular design limits and the von Mises triaxial theory (API TR 5C3 2018). A methodology that allows plotting the API uniaxial force limits on the design limits plot is developed. The study also shows that the results obtained from the industry standard slanted ellipse are identical to those obtained from the horizontal ellipse and circle. One important difference is that the slanted ellipse is based on the zero axial stress datum, whereas the horizontal ellipse/circle uses the neutral axial stress datum. The horizontal ellipse/circle is well suited for calculations involving buckling, compatible with the information used in field operations, and its formulations are less complicated than the tilted ellipse. Therefore, attention is called to the use of the horizontal ellipse/circle in well tubular design.

“Modal Preludes and Fugues in C” by Borislava Stronko: Specific Use of Modal Technology

The relevance of the article. The most pressing need today is to turn to modern samples of polyphonic music, which is due, on the one hand, to artistic practice, and on the other, to rethinking traditional polyphonic forms and techniques in the context of a total experiment and a radical renewal of musical techniques. B. Stronko’s “Modal Preludes and Fugues in C” demonstrate a completely new, author’s version of the interpretation of the polyphonic cycle, which is due to the non-traditional combination of modality with polyphonic principles and methods of development. The change in the functionally centralized fret-tonal system to a radically different, modal, type of modal organization caused significant changes at all tiers of the multilevel organization of the fugue, starting from its core — the theme, ending with the principles of composition and shaping. To trace exactly what specific changes that were caused by the use of modal technique in the framework of the fugue and is the central problem of the study and determines its relevance Scientific novelty: for the first time, all the preludes and fugues of the cycle “Modal preludes and fugues in C” were thoroughly analyzed with an emphasis on the study of the “semantic source” of the polyphonic cycle (fugue), its quintessence (theme) in terms of the influence of the principles of modality on the construction of the fugue.The purpose of the article: to identify the features of the use of modal technique and the specificity of its influence on various structural levels of the fugue in the cycle “Modal preludes and fugues in C” by Boryslav Stronkо, as well as to determine the special features of the composer’s polyphonic thinking. The research methodology includes the use of systemic and functional methods. Main results and conclusions. All fugues from the cycle «Modal Preludes and Fugues in C» by B. Stronko represent an open cycle based on the modal principle of organization. The cycle itself is potentially open and represents the composer’s desire to achieve freedom and emphasize the potential for infinity of the process of creating modes. Each pair of preludes and fugues is limited by a scale of a certain design, which made it possible to create compositions with a pronounced individual flavor. At the level of thematicism: compactness of themes and fugues themselves, intonation specificity, depending on the structure of the fret. With further themes, linearity of development prevails, the composer uses the principle of multivariate repetition (isomelia, isorhythmy, interpolation, combinatorics), which has a certain relationship with rehearsal technique and becomes a specific feature of Boryslav Stronko’s polyphonic thinking. Multivariate repetition of the material, despite the actual changes, enhances the fading effect, being in one place and organically combines with the idea of being in the conditions of one specific sound of the chosen fret. Attention is drawn to the technique of replicating rhythmic-intonational structures — it is a quasi-sequential repetition of a motive in one or several voices at the same time, most often it variably changes in all voices, repeating with a horizontal shift or with the simultaneous use of various techniques (isorhythmy, isomelia, combinatorics). The role of ostinato increases significantly, which, together with the above techniques, contributes to the creation of the effect of hidden internal movement while actually staying in one place. It should be noted that all the above principles, which create the effect of a specific sound and work on the idea of constant rotation in a single sound space, turn out to be stable not only for “Modal preludes and fugues in C”, but also for other works of the composer: “Labyrinth Chord”, 4-part symphony for virtual ensemble (2016), “Time Crystals” (or “Metavariations for metapiano”) is an electronic music cycle (2018).

Compatibility Between API Equations and Design Limits Plots for Ellipse and Circle of Plasticity

This paper presents a methodology to superimpose the American Petroleum Institute (API TR 5C3 2018) uniaxial and triaxial limits on tubular design limits plots. Complications due to a recent change of axis are resolved, producing practical design limits plots that avoid the horizontal shift of the API vertical limits, currently done by the industry. The commonly used slanted ellipse is compared against an adaptation of the circle of plasticity in the form of a horizontal ellipse, showing the convenience of this last one with examples. After the new collapse formulation was made part of the main body of standard API TR 5C3 (2018), the horizontal axis on the standard industry well tubular design limits plot changed. The present study evaluates this redefinition of the horizontal axis. One consequence of this modification is a difficulty plotting the API tension and compression limits. The API horizontal limits (uniaxial burst and collapse) are found to be independent of load case, while the API vertical design limits (uniaxial tension and compression) are dependent on inside and outside tubular pressures. The approaches used by commercial software and industry publications to solve this challenge are reviewed. A new design methodology is developed to link API uniaxial limits to the triaxial theory. The main objective of the study is to establish a mathematical relationship between API tubular design limits and the von Mises triaxial theory (API TR 5C3 2018). A methodology that allows plotting the API uniaxial force limits on the design limit plot is developed. The study also shows that the results obtained from the industry standard slanted ellipse are identical to those obtained from the horizontal ellipse and circle. One important difference is that the slanted ellipse is based on zero axial stress datum while the horizontal ellipse/circle uses neutral axial stress datum. The horizontal ellipse/circle is well suited for calculations involving buckling, it is compatible with the information used in field operations and its formulations are less complicated than the tilted ellipse. Therefore, attention is called to it.

Usefulness of data augmentation for visual field trend analyses in patients with glaucoma

AimTo investigate the usefulness of data augmentation in visual field (VF) trend analyses in patients with glaucoma.MethodThis study included 6380 VFs from 638 eyes of 417 patients with open-angle glaucoma. Various affine transformations were applied to augment the VF data: (1) rotation, (2) scaling, (3) vertical and horizontal shift and (4) a combination of these different transformations. Using pointwise linear regression (PLR), the total deviation (TD) values of a patient’s 10th VF were predicted using TD values from shorter VF series (from first to third VFs (VF1–3) to first to ninth VFs (VF1–9)) with and without VF data augmentation, and the root mean squared error (RMSE) was calculated.ResultsWith PLR, mean RMSE without VF augmentation averaged from 3.95 (VF1–3) to 19.01 (VF1–9) dB. The RMSE was significantly improved by applying the different transformations: (1) rotation (from VF1–3 to VF1–7), (2) scaling (from VF1–3 to VF1–6), (3) vertical and horizontal shifts (from VF1–3 to VF1–4) and (iv) a combination of these (from VF1–3 to VF1–7). Progression rates in VF1–10 had better agreement with those in shorter VF series when a combination of affine transformation was applied. The differences in rates were between 1.9 (VF1–3) and 0.39 (VF1–9) dB if augmentation was used, which was significantly smaller than that observed when augmentation was not applied (from 2.6 with VF1–3 to 0.26 dB with VF1–9).ConclusionIt is useful to apply VF data augmentation techniques when predicting future VF progression in glaucoma using PLR, especially with short VF series.

The study of the ferroconcrete beams with thrust on the foil bearings during short-term dynamic loading

While designing and maintaining ferroconcrete beam constructions subjected to a short-term dynamic loading, it is necessary to consider the emergence of the thrust reaction; this leads to a considerable increase of durability and fracture strength. It is also necessary to consider the use of foil bearings as the power-intensity increase of the researched constructions. The aim of the experimental research is to expose the reasonability of using foil bearings in thrust constructions. The paper presents the results of the experimental research of ferroconcrete beam constructions with thrust on foil bearings during short-term dynamic loading. The influence of the thrust on the durability, deformability and fracture strength of ferroconcrete constructions during short-term dynamic loading, as well as joint use of foil bearings and limitation of support contour horizontal shift are studied. The results of the research indicate the positive effect of using foil bearings in the constructions with thrust.

Advances on coastal erosion assessment from satellite earth observations: exploring the use of Sentinel products along with very high resolution sensors

This work proposes the use of automatic co-registered satellite images to obtain large, high frequency and highly accurate shorelines time series. High resolution images are used to co-register Landsat and Sentinel-2 images. 90% of the co-registered images presented vertical and horizontal shift lower than 3 m. Satellite derived shorelines presented errors lower than mission’s precision. A discussion is presented on the applicability of those shorelines through an application to Tordera Delta (Spain).

Study of Interaction Patterns Between Evolving Interfaces Due to Boiling Around Different Arrangements of Heated Cylinders

An effort has been made to numerically study the interactions between the vapor films generating from multiple heated cylinders placed in a saturated water pool with a view to understand the influence of neighboring interface on growth of vapor films. Lagrangian smoothed particle hydrodynamics (SPH) has been used for domain discretization and interface reconstruction. Unconstrained growth of vapor film around a cylinder is simulated first and the nature of vapor dynamics has been taken as a base case for the study of interaction patterns. Vapor growth has been understood through temporal phase contours, azimuthal thickness variation, and trajectory of the centroid of the vapor mass. It has been shown that the presence of cylinder in vertical neighborhood results in suppression of vapor film generating from the bottom cylinder, whereas, the vapor films generating from two cylinders placed in horizontal neighborhood experience a horizontal shift. Studies have also been made to observe multidirectional interactions of vapor films with heated cylinders placed in an inline array, vertically staggered and horizontally staggered arrangements. It has been found that the highest deviation from unconstrained growth occurs in case of the center cylinder in a horizontally staggered arrangement as compared to others. Mutual interaction coefficient and indices are proposed to judge the best possible arrangement in case of a requirement for placement of stacked cylinders.