bluuebunny/crossref_metadata_2025 huggingface dataset:
STRESS STATE AND CONDITIONS FOR CRACK INITIATION IN THE ADHESION LAYER OF THE COMPOSITE
Authors: Bogacheva V. E , Glagolev V. V , Glagolev L. V , Markin A. A
Published: April 2023

The paper deals with the elastic deformation of a composite consisting of plates connected with an adhesive layer on the basis of the interaction layer concept. The layer thickness is taken as a linear parameter. Under loading by the normal separation in the case of plane deformation, the triaxial stress state of the adhesive layer is taken into account. From the general variational setting, by using the hypothesis of flat sections, the problem is formulated in a differential form. Within the framework of a simplified formulation, an analytical solution is found that agrees with the numerical solution obtained by the finite element method. It is shown that Poisson's ratio of the adhesive layer significantly affects its stress state, in which there is a coincidence of the two principal stresses. For weakly compressible adhesion layers, a stress state close to hydrostatic tension is realized. In order to analyze the stress state of the adhesion layer, which is singular at extremely small values of the linear parameter, it is proposed to use the energy product (EP), local stresses (LS) and local deformations (LD). EP is determined as the product of the specific free energy of the layer and the linear parameter, and LS (LD) is determined as the product of stresses (deformations) and the square root of the linear parameter. It is shown that these characteristics are not singular with respect to small layer thicknesses and do not depend on the linear parameter. It was found that the value to which the EP converges at a fixed external load and the linear parameter tends to zero does not depend on the mechanical properties of the adhesive, and the LS (LD) values depend on the properties of the adhesive. At the critical load of crack initiation in the adhesive, the LD in the direction of the separation is significantly (by several orders of magnitude) higher than the LD in the orthogonal direction. In this case, the LS and LD of separation make the main contribution to the formation of the EP. A method is proposed for determining the critical value of the EP corresponding to crack initiation in the adhesive based on the use of the maximum external load from the experimental R-curves.
Theories of plasticity under complex loading along flat trajectories of deformations
Authors: Bondar V. S , Abashev D. R , Fomin D. Ju
Published: April 2023

The paper considers variants of theories of plastic flow with combined hardening, which are widely used in applied calculations of structures. A comparative analysis of the theories under complex loading along flat strain trajectories is carried out and covers the entire range of strain paths from multilink polylines to curved trajectories of constant and variable curvatures. The strain path from medium to large curvatures are considered. The analysis of the research results is carried out in the vector space of A.A. Il’yushin. We consider plane trajectories of deformations in the form of a square, three circles passing the origin of coordinates, and trajectories in an asteroid-like form. The results of the calculations are compared with the results of the experimental studies of the response stress trajectories, scalar and vector properties. Variants of theories are considered: isotropic hardening model; Ishlinsky-Prager-Kadashevich-Novozhilov model (linear kinematic and isotropic hardening); model similar to Ono-Wang's model; the Armstrong-Frederick-Kadashevich model (the Korotkikh model is based on this model); the Shabosh model with three evolutionary Armstrong-Frederick-Kadashevich equations; Themis model based on the invariant theory of plasticity; Bondar model with a three-term structure of the evolutionary equation for kinematic hardening. We give the material parameters (functions) that close the variants of plasticity theories. A satisfactory agreement with the experiment for all deformation trajectories is achieved in calculations based on the models of Ishlinsky-Prager-Kadashevich-Novozhilov, Shabosh and Temis. The difference between the results of calculations and experiments does not exceed 30 %. The best agreement with the experiment is achieved on the basis of the Bondar model with the difference between the results of the calculations and experiments for all trajectories less than 10 %.
Elastic diffusion vibrations of an isotropic Kirchhoff-Love plate under an unsteady distributed transverse load
Authors: Yu Gu , Zemskov A. V , Tarlakovskii D. V
Published: April 2023

We investigated an unsteady elastic diffusion vibration of a simply supported rectangular isotropic Kirchhoff-Love plate. The plate is under the action of a distributed transverse load. A model that describes coupled elastic diffusion processes in a multicomponent continuum is used for the mathematical problem formulation. The model is taking into account the diffusion fluxes relaxation. The transverse vibration equations of a rectangular isotropic Kirchhoff-Love plate with diffusion were obtained from the model using the d'Alembert variational principle. The initial-boundary value problem of a freely supported isotropic rectangular plate bending is formulated on the basis of the obtained equations. The plate is under the action of elastic diffusion perturbations distributed over the surface. The problem solution of an unsteady elastic diffusion plate vibration is sought in an integral form. The surface Green's functions are the kernels of the integral representations. To find the Green's functions, we used the Laplace transform in time and the expansion into double trigonometric Fourier series in spatial coordinates. Green's functions in the image domain are represented in the form of rational functions and depend on the Laplace transform parameter. The transition to the original domain is done analytically through residues and tables of operational calculus. The surface Green's function analytical expressions are obtained. As a calculation example, we considered a freely supported elastodiffusive plate under the action of suddenly applied unsteady bending moments distributed over the plate surface. By using a three-component continuum, a numerical study of interactions between unsteady mechanical and diffusion fieldsis done for an isotropic plate. The influence of relaxation effects on the kinetics of mass transfer is investigated. The solution is presented in the analytical form, as well as in the graphs of the displacement fields and concentration increments on time and coordinates. At the end of the publication, the main conclusions are given about the fields coupling effect and the relaxation of diffusion fluxes on the stress-strain state and mass transfer in the plate.
Simulation of the hot isostatic pressing process
Authors: Khlybov A. A , Belyaev E. S , Ryabtsev A. D , Ryabov D. A , Belyaeva S. S , Getmanovsky Yu. A , Yavtushenko P. M
Published: April 2023

This work, models the compaction of a dispersed body under the conditions of a hot isostatic pressing (HIP) cycle using the example of the manufacture of compacts from VZh159ID powder and Inconel alloy 718. For the research, VZh159ID powder of fraction -70 + 25 μm, bulk density of 3.77 g/cm3 (4.83 g/cm3 after tapping), fluidity of 2.3 g/s, specific surface area of 446 cm2/g, and average particle size was used according to Fisher 16 microns, as well as Inconel alloy 718 powder of fraction -315 + 25 microns, bulk density 3.84 ... 4.58 g/cm3 (4.52 ... 5.24 gcm3 after tapping), fluidity 1.58 ... 1.90 g/s, specific surface 330 ... 376 cm2/g and average particle size according to Fischer 19.0 ... 19.5 microns. Before the HIP cycle, the powder backfills underwent thermal degassing in vacuum, since powders with such a high specific surface are subject to rapid gas sorption. Gases on the surface of the powder body as a result of the HIP cycle can form non-metallic inclusions that reduce the properties of the compact. In the microstructure of compacts after HIP, there is no network of residual boundaries from granules (PPBs-Prior Particle Boundaries), which indicates an effective technology of vacuum degassing of the powder. Simulation of the compaction process was carried out according to the modernized equation of E. Ryshkevich, constants b were selected for the materials considered. The results of the experiments of interrupting the HIP cycle and data on the strength of the samples at high temperatures obtained by selective laser sintering were used as the initial data for modeling. The proposed modeling method is quite simple (does not require experiments on an interrupted HIP cycle) due to the shown possibility of experimentally determining the strength characteristics of alloys at elevated temperatures on samples obtained by selective laser sintering. The analysis of the obtained microstructures (estimation of porosity) of the samples after HIP, having different density values, shows a good agreement of the proposed model with the real process of compaction in the gasostatic extruder.
The potential of using SWCNTs, MWCNTs and CNFs capable of increasing the composite material dimensional and technological stability as modifiers of a polymer matrix
Authors: Obvertkin I. V , Pasechnik K. A , Vlasov A. Y
Published: April 2023

In this study, the effect of carbon nanofibers (CNN), single-wall carbon nanotubes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs) on the warpage expected value and warpage dispersion of a plate made of a fibrous composite material are investigated. Laminates with fiber disorientation were considered as asymmetric and the model proposed by Dano and Hyer was used to evaluate the warpage. The results obtained confirm that the addition of carbon nanoparticles as a modifier to the polymer matrix of a fibrous composite material can increase the dimensional stability (the mathematical expectation of the standard deviation) and the technological stability of the reinforcement scheme (the variance of the standard deviation of the composite plate). Modeling of the warpage of plate, taking into account the possible disorientation of the fiber, showed a decrease in the warpage dispersion by 12.6 and 26.6 % with the modification of the SWNTs and MWCNTs, respectively. The coefficient of thermal extension (CTE) of a nanostructured polymer matrix with various fillers were experimentally determined. It was found that carbon nanomodifiers are more effective as compensators for the thermal expansion of the polymer matrix in composite laminates reinforced with carbon fibers than the polymer matrix without macrofibers. The addition of 0.05 % SWCNTs, 1 % MWCNTs to the epoxy resin reduces the CTE by 9.7 and 15.4 %, respectively. At the same time, the addition of a similar amount of nanoparticles to the epoxy matrix of the fiber composite reduces the CTE in the transverse direction by 15.56 and 35.8 %, respectively. On the basis of the obtained results, the dependences of the transverse CTE of the polymer composite material, the mathematical expectation of the standard deviation, and the variance of the standard deviation of the composite plate form accuracy on the concentration of the modifier were constructed. According to the obtained data, it can be concluded that in order to reduce the mathematical expectation and the variance of the warping of the composite material, there is an effective concentration, the increase of which is impractical, despite the further decrease in the transversal CTE.
Elastic-plastic invariant of autowave plasticity
Authors: Zuev L. B , Barannikova S. A , Gorbatenko V. V
Published: April 2023

It is shown in the work that plastic flow in solids develops always in localized manner. A macroscopic scale ~ 10-2 m characterizes the localization. The localized flow zones form the pattern of localized strain, which is the projection of the autowave processes of plastic flow, developing in the volume, on the observed surface of the tested specimen. One can observe the pattern with the help of speckle-photography method. The investigations of various materials allowed to establish that the pattern of localized deformation is the information source for a kinetics of deformation processes. A general characteristic of localized plastic flow in solids is the elastic-plastic invariant of deformation which couples the typical characteristics of localized plastic flow autowaves with the same for the elastic waves in crystal lattice. The quantity of the invariant ratio is defined for nearly forty various materials (BCC, FCC, HCP metals and alloys, alkali-halide crystals, ceramics, rocks) studied in the conditions of active elongation and compression at the temperature range 143-420 K. The physical considerations are presented to explain the invariant origination and its relation to other physical characteristics of crystal lattice, in particular, the Debye temperature. In the light of these considerations, it is possible to explain the meaning and the origin of the invariant, and to derive numerous consequences from them. In fact, the set of these consequences comprehend all the regularities of developed plastic flow processes and allows to consider the elastic-plastic invariant of deformation as the master equation for developing this day autowave approach to physical theory of plastic deformation.
Numerical simulation of brush seal tests
Authors: Bondar V. S , Rodin E. V
Published: April 2023

A numerical analysis of deformation of the brush seal wire package as part of dynamic rotor&stator system of gas turbine engines is describes. The estimated definition of the reaction force of the brush package is based on solving the contact problem of the interaction of bristles with each other, with the rotor and the rear plate of the seal case, taking into account the action of the distributed gas flow pressure. Comparison of the results obtained with the data of well-known estimated and experimental studies. According to the results of calculations, it was noted that the accounting of the spatial contact interaction of the elements of the brush seal significantly affects on reaction force value and, accordingly, on the brush package rigidity. In the presence of a gas pressure drop on the compaction, the results of calculations on a simplified half-analytical model based on the analysis of the deflection of one bristles according to the model of the flat bending of the console straight beam, and the spatial model differ in order. It is necessary to take into account this effect when calculating the wear of the brush seal and the forecast of its effectiveness with the course of operation. A characteristic feature of the dependence of the reaction of the brush package from the magnitude of the rotor displacement is the presence of hysteresis in the "load - unloading" cycle due to friction in the system. The impact of gas flow on the bristles significantly increases the scope of hysteresis loops and changes its shape. On the scale of the loop also strongly affects the coefficient of friction pair "schedules - rotor". The obtained dependences of the reaction of the brush package from the magnitude of the tension / displacement of the rotor (hysteresis loops) allow you to clarify the calculated mathematical model of the brush seal after testing on the stand.
Calculation of VAT and assessment of the strength of a segmented cylindrical shell made of composite materials with metal inserts
Authors: Rogozhnikova E. N , Anoshkin A. N , Bulbovich R. V
Published: April 2023

The paper considers a cylindrical segmented shell - a pressure cylinder made by winding from unidirectional roving. The shell has a different thickness and reinforcement scheme for segments, and metal embedded elements on the front and rear ends of the shell for fixing the covers. The problem of calculating the stress-strain state and estimating the strength of the shell under loading by internal pressure is posed. To solve the problem, a two-level numerical mathematical model of the shell is developed. At the first level, the shell is modeled using the effective characteristics of the composite material by segments. At the second level, the deformation of individual segments of the shell is modeled - the front and rear joint nodes with metal embedded elements and a pin-pin connection with an explicit description of the segment reinforcement scheme. The boundary conditions for the segment deformation problem are determined as a result of calculating the shell VAT using the first-level model. The developed model is compared with the results of bench tests of the shell for the effect of internal pressure. Based on the results of solving the problem for the shell segments, the analysis of interlayer stresses in the contact zone of the composite shell - metal embedded was performed and estimates of the structural strength were obtained.
Solution of a mixed nonaxisymmetric problem of the theory of elasticity for anisotropic bodies of revolution
Authors: Ivanychev D. A
Published: April 2023

The paper developed a technique for solving mixed nonaxisymmetric problems of the theory of elasticity for bounded bodies of revolution made of a transversely isotropic material under the action of surface forces specified according to a cyclic law. The technique involves the development of the energy method of boundary states, which is based on the concepts of spaces of internal and boundary states, conjugated by isomorphism, which makes it possible to establish a one-to-one correspondence between the elements of these spaces. The internal state includes the components of the tensor of stresses, deformations, and the displacement vector. The boundary state includes efforts and displacements at the boundary of the body. The isomorphism of the state spaces is proved, which allows finding the internal state to be reduced to the study of the boundary state isomorphic to it. The basis is formed on the basis of the general solution of the boundary value problem of elastostatics for a transversely isotropic body of revolution. Orthogonalization of state spaces is carried out, where the internal energy of elastic deformation is used as scalar products in the space of internal states; in the space of boundary states, the work of external forces is used. Finally, finding the desired state is reduced to solving an infinite system of algebraic equations for the Fourier coefficients. The solution of the problem with mixed boundary conditions for a circular in plan cylinder of transversely isotropic coarse dark gray siltstone with anisotropy axis coinciding with the geometric axis of symmetry is presented. The solution is analytical and the characteristics of the stress-strain state have a polynomial form. Explicit and indirect signs of convergence of problem solutions and graphical visualization of the results are presented.
Postbuckling Behavior of Compressed Bars with Nonlinearly Elastic Supports
Authors: Kayumov R. A
Published: April 2023

Supercritical bending of a rod compressed by a longitudinal force and having a non-linearly elastic resistance to rotation of its axis in hinged supports is considered. Hooke's law is adopted for the rod material. The deflection is presented as a trigonometric series, in which only the first three terms are left. Through this row, the angle of inclination of the axis of the rod is expressed. It is chosen as the desired function, with respect to which a resolving nonlinear integro-differential equation is obtained. To simplify it, the case is considered when the bent axis of the rod is a gentle curve. It is revealed that the usual approach, in which the compressive force is given, leads to a trivial solution with zero values for the coefficients of this series. Therefore, the first coefficient of the series, through which the deflection is represented, was chosen as the initial parameter. The equation containing the remaining desired coefficients and load was solved by the simple collocation method, since the use of the predetermined collocation method is impossible due to the nonlinearity of the resulting system of equations. The calculation results were analyzed depending on the choice of collocation points, which showed a small difference between the obtained solutions (the quadratic discrepancy between the calculated values did not exceed one percent, which indicates sufficient accuracy of the deflection approximation in the form proposed in the work). In contrast to the usual approach used in numerical methods, here it is not necessary to enter any parameter of the loading process (such as the length of the arc in the arc method) to pass the limit points. An approach is presented for an approximate calculation of the compliance of the considered rods in compression, taking into account their supercritical bending. The results of numerical studies of the supercritical behavior of rods for various geometric and mechanical characteristics of rods and supports are presented, and dependences between various parameters of the stress-strain state are obtained. Their analysis made it possible to reveal a number of features in the behavior of the considered rods depending on the properties of the nonlinear elastic resistance of the supports. In particular, it was found that under the considered parameters of the system under consideration, the compression force and the angle of inclination of the rod on the support are related by a relationship close to linear, the compliance of the compressible rod can increase by tens or more times depending on the stiffness of the springs, the rod can lose stability by snap at some values parameters of nonlinear elastic supports.
A NUMERICAL ANALYSIS OF FORCED STEADY-STATE VIBRATIONS OF AN ELECTRO-VISCOELASTIC SYSTEM IN CASE OF A JOINT IMPACT OF ELECTRICAL AND MECHANICAL LOADS
Authors: Iurlova N. А. , Oshmarin D. A. , Sevodina N. V.
Published: April 2023

In the current paper an estimation of a mechanical response of a structure on joint mechanical (force and kinematic) and electrical (voltage and current) impacts taking into account different options of their combinations was carried out. A mechanical response was esteemed basing on solution to the problem of natural vibrations for piecewise-homogeneous electro-viscoelastic bodies. A cantilever plate with piezoelectric element attached to its surface was chosen as an object under study. The plate was made of viscoelastic material the mechanical properties of which are described using complex dynamic moduli. A piezoelectric ceramic material was chosen as the one for piezoelectric elements. An amplitude of forced steady-state vibrations of a component of displacement vector that is perpendicular to the surface of the plate was chosen as a quantity that characterize a mechanical response. Variational equation of motion of the object under consideration is formulated based on relations of linear elasticity, linear viscoelasticity and Maxwell’s equations for a conducting media in a quasistatic approximation. Ranges of changing of values of excitation impacts for vibration modes taken into account were chosen on the basis of values of natural vibrations frequencies obtained from the solution to natural vibration problem for electro-viscoelastic bodies. Numerical implementation of the stated problem was performed in finite element software package ANSYS. Some characteristic peculiarities of a mechanical response depending on a type and magnitude of external impact were obtained as the result of the carried out numerical experiments. There was demonstrated that in case of joint impact of two loading factors there reveals an additional capability of control a mechanical response of an electro-viscoelastic system.
IDENTIFICATION OF THE IMPACT POSITION IN A REINFORCED CONCRETE STRUCTURE BASED ON THE ANALYSIS OF THE RESPONSE OF VIBRATION SENSORS
Authors: Tsvetkov R. V. , Shardakov I. N. , Glot I. O. , Gusev G. N. , Yepin V. V. , Shestakov A. P.
Published: April 2023

The article presents the results of an experiment to study the vibration response of a large-scale reinforced concrete model structure to an impulse load. The load was a series of impacts along the normal to the surface of the element and was applied to all the main structural ele-ments (columns, crossbars and floor slabs). The vibration response was recorded by a system of sensors-accelerometers distributed over the structural elements and synchronized with the accelerometer mounted on the striker. The results of measurements of acceleration vibrograms were saved as digital files. An array of vibrograms recorded by the entire complex of sensors in response to test impacts on the main structural elements made up a vibration portrait of the structure. As a result of processing this information, an array of data was obtained on the propa-gation time of the vibration signal from each signal source to each of the sensors of the registra-tion system (basic array of responses).Key words: Impact localization, accelerometer, The data obtained were used to solve the problem of determining the location of an arbi-trary impact on a structure. To do this, the vibration response recorded by the sensor system during an arbitrary impact was compared with the base array of responses. The comparison was made on the basis of the calculation of the pair correlation coefficients. The resulting spatial distribution of the correlation coefficients made it possible to identify the position of the shock load application. It corresponds to the structural element that has the maximum value of the correlation coefficient. The proposed algorithm was demonstrated on an example where one of the test shocks that participated in the FORMATION of the basic vibration portrait was used as an unknown load. In a numerical experiment using the proposed algorithm, it was found that the accuracy of the impact site identification corresponds to the characteristic step of the structural elements. It is shown that the accuracy correlates with the number of sensors of the registration system and their distribution throughout the structure. The developed algorithm for identifying the place of impact load application can be effec-tively used in the development of automated systems for deformation monitoring.
SIMULATION OF INTERIM FORGING OF DEPOSITED PRODUCTS IN ANSYS MECHANICAL APDL (IMPLICIT ANALYSIS)
Authors: Smetannikov O. Yu. , Trushnikov D. N. , Anisimov A. A.
Published: April 2023

The paper considers the problem of simulating the interim forging during additive manufac-turing. Wire-arc additive technologies are associated with formation of technological residual stress fields, porosity, inhomogeneous structure and anisotropy, as well as unwanted defects, such as cracks, delamination or warping of the part. Interlayer hardening via forging both com-pensates such disadvantages and improves the mechanical properties of structures. Mathemat-ical modeling is one of main methods of studying these processes. There are a lot of publica-tions on modeling the formation of fields of residual stresses and heat shrinkage deformations in products obtained using additive technologies, including the method of wire welding. The work aims at checking the adequacy of using ANSYS Mechanical APDL for numerical modeling of interim metal forming processes. In this work, the Johnson – Cook viscoplastic model from Ex-plicit Dynamics was adapted to the capabilities of ANSYS Mechanical APDL for three materials: Amg6, 12X18H10T, VT6. As a physical model in ANSYS Mechanical APDL, a multilinear iso-tropic MISO plasticity model is chosen, which, unlike the Johnson – Cook model, does not take into account the effect of strain rate on the elastic-plastic behavior of the material. The values of the material constants for the MISO model are identified. The adequacy of replacing the non-stationary statement with a quasi-static one is proved, due to a slight loss of accuracy. A three-dimensional model of bar forging for three types of materials was built and implemented, its identification and verification were carried out by comparing with the results of a full-scale exper-iment. A good agreement between the calculated data and experiment is shown. Based on the data obtained, a conclusion was made about the admissibility of using the implicit solver ANSYS Mechanical APDL for calculating the processes of interim forging of the deposited products with acceptable accuracy.
COMPLIANCE AMBIENTAL E A MUDANÇA DE CONSCIÊNCIA NA INDÚSTRIA DA MODA
Authors: Lewinsky Bruna Paz , Bastian Maria Eduarda Gasparotto de Azevedo
Published: April 2023

O presente artigo tem o objetivo de analisar a relevância do Compliance ambiental na Indústria da moda, considerando aspectos legais ligados à proteção e preservação do meio ambiente, a fim de inserir uma conduta ética na cadeia de produção através da implementação da sistemática em empresas que atuam ramo da moda, visando uma Indústria rentável e saudável. Para tanto, este trabalho recorre a um aporte teórico, relacionando-o à aplicação de normas ambientais em marcas que possuem o propósito de proteger o meio ambiente, buscando uma mudança de mentalidade direcionada à novos hábitos, condutas e maneiras de se posicionar perante o mercado.
O DANO MORAL COLETIVO DECORRENTE DE MAUS-TRATOS A ANIMAIS DOMÉSTICOS
Authors: Vasques Teresinha Wanke , Rammê Rogério Santos
Published: April 2023

O presente artigo objetiva a análise da possiblidade de condenação na esfera civil de danos morais coletivos em decorrência do delito descrito na Lei de Crimes Ambientais referente a maus-tratos a animais doméstico. Inicialmente, há uma contextualização de como a legislação pertinente aos atos de crueldade com os animais vem se desdobrando no Brasil, após demonstra-se como os seres humanos desenvolveram vínculos afetivos com os animais que se iniciaram ainda no período paleolítico perdurando até hoje, em seguida, demonstrasse o que é o dano moral coletivo e, por fim, é feito um estudo jurisprudencial de julgados de diversos tribunais estaduais brasileiros para verificar como a matéria vem sendo tratada no ordenamento.
Characterisation of flipped classroom teaching in multigrade rural schools
Authors: Castillo-López Javier , Domínguez Figaredo Daniel
Published: April 2023

Multi-age classrooms are student-centred classrooms. Flipped classroom teaching promotes active learning. In the research reported on here, we analysed the characteristics of flipped classroom teaching in the context of multigrade rural schools. Two main questions were raised: whether the characteristics of rural multigrade classrooms require adapting the flipped classroom method, and whether there is a particular framework for applying this method in such classrooms. A questionnaire was administered to and interviews held with teachers who used flipped classroom in their multigrade classrooms. The data show a typology of flipped classroom strategies adapted to multigrade classrooms. It is also concluded that applying flipped classroom in multi-grade classrooms requires significant changes in the instructional design and classroom learning phase. No changes were detected during the previous phase of individual work outside the classroom. A regular framework for the application of the flipped classroom method in multigrade rural schools could not be determined due to the heterogeneity of this kind of class.
Determinants of Hypertension Treatment Adherence during the COVID-19 Pandemic: Lesson Learned from Various Studies Sites in Indonesia
Authors: Deanasa Raehan Satya , Zalfa Alifa Alya , Patahuddin Nurul Mufliha , Zulfa Lathifah Dzakiyyah , Hana Sofia , Putra Indrakusuma Anak Agung Bagus , Prasetyo Aizar Vesa , Malik Gita Julianti , Tosadapotto Hesti Azzahra , Suwandri Raza Syahlevi , Mahmudi Muhammad Nur , Syakurah Rizma Adila
Published: April 2023

Background: Hypertension is the most common comorbid disease which can cause further complications in COVID-19 patients. On the contrary, the pandemic has also caused lower health services and adherence to hypertension therapy. This study aimed to examine the impact of the COVID-19 pandemic on medication adherence in people with hypertension in Indonesia.Methods: The research was conducted using an analytical quantitative method. Patients with hypertension from seven islands across Indonesia were recruited based on eligibility criteria during Bulan Bakti 2021, a social outreach by Ikatan Senat Mahasiswa Kedokteran Indonesia about basic health across Indonesia. The demographic and medication history of the respondents were recorded. The Indonesian version of the Morisky Medication Adherence Scale (MMAS-8) questionnaire was distributed, and the medication adherence level was assessed.Results: A total of 1155 patients, mainly females (62.2%) participated in this study. More than half of the patients had low adherence (55.25%). Males (Adjusted Odd Ratio (AOR) 0.777 [CI 95% 0.529–1.019]), employed (AOR 0.857 [CI 95% 0.495–1.483]), higher income (AOR 0.522 [CI 95% 0.393–0.713]), and those who had information from healthcare worker (AOR 0.583 [CI 95% 0.361–0.878]) were found to have better medication adherence in multivariate logistic regression test.Conclusion: Medication adherence level in patients with hypertension during the pandemic is markedly low. Integrated preventive and promotive measures, especially from healthcare workers, are needed to prevent further morbidity and mortality.
Monitoring Obstacles of Toddlers Growth in Public Health Center Margahayu Raya Bandung City during the COVID-19 Pandemic: From Cadre Perspective
Authors: Sekarani Natasya Alifah , Herawati Dewi Marhaeni Diah , Rinawan Fedri Ruluwedrata
Published: April 2023

Background:Toddler growth monitoring is one of the specific nutritional interventions used to accelerate stunting reduction. The COVID-19 pandemic has reduced various ‘Minimum Service Standards‘coverages, including toddler growth monitoring. This study aimed to explore the obstacles of toddler growth monitoring at the Integrated Service Center (Pusat pelayanan terpadu, Posyandu) during the COVID-19 pandemic. Methods: This was a qualitative study with an interpretivism paradigm. The unit of analysis was Posyandu of Margahayu Raya Public Health Center, Bandung City, West Java. Primary data were obtained through in-depth interviews with 10 cadres from different Posyandu from September-December 2021. The data were collected using a semi-structured interview guide and a recorder, and analyzed using NVivo software.Results: During the COVID-19 pandemic, toddler weighing had been suspended for several months. Starting in August 2020, cadres and public health center officers worked to ensure that toddlers’ weight, body length, and height could be monitored despite the numerous obstacles.Conclusion: The obstacles to toddler growth monitoring are inadequate instruments of toddler body height measuring during home visits, minimum cadre skills, a lack of toddlers’ mother awareness to bring their toddlers to Posyandu, and a lack of public awareness to follow health protocols.
Intervention of Kusuma Milk-Shake Drink on Cervical Dilatation and Duration of Labor: Experience from Bengkulu, Indonesia
Authors: Baska Dwie Yunita , Wahyuni Elly Elly , Yulyana Nispi
Published: April 2023

Background: Labor processes require energy consumption regulated by a complex nervous system and hormonal response. Thus, the intensity of maternal nutritional intake since pregnancy should be highly considered for physiological delivery. Nutrients that are high in energy and provide fast-decomposing glucose intake should be chosen by the mothers. Kusuma is a kind of drink made from dates, milk, and honey. This study aimed to analyze the effect of Kusuma milk-shake drink implementations on cervical dilatation and duration of labor.Methods: An experimental study was conducted by post-test only with a controlled group design, including 34 mothers with term pregnancy, which was intervention groups and controls. A completely randomized design in two different places was conducted. Data were analyzed using Shapiro-wilk, independent sample T-test, and Mann-Whitney. Results: There was a significant effect of Kusuma milk-shake implementation on cervical dilatation (p=0.000). The dilatation process was found to be 5.5 times faster, and the duration of labor (p=0.000) was observed to be 9.7 hours faster than the control group.Conclusions: Implementation of the Kusuma milk-shake has a significant effect on the acceleration of cervical dilation and the duration of labor. This research is expected to improve the quality of midwifery services as an effort to realize the concept of a Continuum of Obstetric Care.
FACE RECOGNITION ALGORITHM BASED ON OPTIMAL WEIGHTED MULTI-DIRECTIONAL LOG-GABOR FEATURES
Authors: Gao Zhengping , Kong Fansheng , Tao Jiagui , Chen Min
Published: April 2023

In order to improve the performance of face recognition, a face recognition method based on an adaptive fusion of multi-directional and multi-scale Log-Gabor features is proposed. First, the multi-direction and multi-scale Log-Gabor transform is applied to face images. Then the Log-Gabor feature maps of different scales are fused to extract the Gist vectors of the fused feature maps. In addition, the mutual information algorithm is used adaptively to calculate the weights of Gist vectors. Finally, the adaptive
weighted Gist vector is used as the feature vector of face images, and the K-nearest neighbor classification
algorithm is used to realize face recognition. According to the face recognition experiments on WIDER FACE data set and MAFA occlusion face data set, the accuracy of the proposed method is presented. Compared with the classical face recognition algorithms, the effectiveness of the proposed
method is verified.
Synthesis of alkali-activated mortar using phosphogypsum-neutralised bauxite residue
Authors: Pratap Bheem , Mondal Somenath , Hanumantha Rao Bendadi
Published: April 2023

The present study was aimed at perspective utilisation of two wastes, bauxite residue (BR), an extremely alkaline material, and phosphogypsum (PG), a highly acidic substance, of entirely different natures. Development of alkali-activated mortar targeting pavement applications was explored. As BR and PG alone proved to be ineffectual in developing geopolymer/alkali-activated mortar because of undesirably low compressive strength, the challenge lies in synthesis of alkali-activated mortar with high strength using a combination of these wastes. PG proportions of 10, 20, 30, 40 and 50%; sodium hydroxide (NaOH) molarities of 8, 10, 12 and 14 M; and sodium silicate (Na2SiO3)/sodium hydroxide ratios of 0.5, 1.0, 1.5, 2.0 and 2.5 were chosen as variable parameters to develop the mortar. From the comprehensive experimental results, 30% PG, 12 M sodium hydroxide and sodium silicate/sodium hydroxide ratio of 1.5 were found as the optimum parameters for synthesising the mortar. It was demonstrated that the mortar made at a 70:30 combination of BR and PG had superior compressive strength of 31.24 MPa, minimum abrasion loss of 1.52 mm and water absorption of <7%, apart from constraining leaching of potentially toxic elements. On account of mechanical, durability and environmental performance, the present study recommends the aforementioned combination as ideally suitable material in pavement applications.
Apport de la tomographie par émission de positons dans la prise en charge des cancers du testicule
Authors: BONARDEL G. , GONTIER E. , DECHAUD C. , SORET M. , FOEHRENBACH H.
Published: April 2023

La Tomographie par émission de positons (TEP) au 18F-Fluorodéoxyglucose (FDG) est une technique d'imagerie
scintigraphique en plein développement depuis le début des années 90 et voit sa place grandir au sein des stratégies
diagnostiques et thérapeutiques en cancérologie. La dernière génération d'appareil associant TEP et Tomodensitomètre à
rayons X (TDM) permet de coupler informations métaboliques et morphologiques en une seule procédure d'imagerie
améliorant encore les performances de la technique. Dans les cancers du testicule, les résultats de la TEP-FDG sont
désormais bien connus. Sa principale application est l'évaluation des masses résiduelles après traitement des tumeurs
germinales séminomateuses. En revanche, du fait de son inaptitude à différencier lésions de tératome mature actives des
lésions cicatricielles non actives, son utilisation est limitée dans les tumeurs germinales non séminomateuses. En raison
de sa capacité à explorer le corps entier et de ses performances souvent supérieures à l'imagerie radiologique, la TEPFDG
présente potentiellement un intérêt lors du bilan d'extension initial dans certaines situations atypiques et également
dans le cas particulier des récidives occultes avec ré-ascension inexpliquée des marqueurs tumoraux. Enfin, l'étude de la
réponse à la chimiothérapie est également une application d'intérêt croissant.
Réinsertion professionnelle après tumeur germinale
Authors: PAVIC M. , PASQUET F.
Published: April 2023

Les tumeurs germinales testiculaires surviennent avec un pic de fréquence chez les hommes jeunes. Aussi peuvent se
poser des problèmes en terme d’aptitude à l’engagement ou au réengagement dans l’armée. Passé le cap de 2 ans après
traitement, le risque de rechute devient exceptionnel mais survient alors une majoration du risque cardiovasculaire
notamment en raison d’un risque accru de syndrome métabolique. La fatigue après cancer testiculaire représente aussi un
problème car significativement plus fréquente comparativement à une population du même âge. En offrant la possibilité
aux patients d’effectuer une activité physique régulière, ces deux principaux risques sont diminués permettant (sous
réserve de l’absence de complications des traitements immédiatement présentes) de redonner à l’individu une aptitude
sans restriction.
Prévention des traumatismes sonores aigus à l’unité
Authors: CASANOVA F. , SAROUL N. , NOTTET J.-B.
Published: April 2023

L’incidence des traumatismes sonores aigus reste élevée en milieu militaire malgré des efforts de prévention. Le but de
notre étude était d’évaluer l'utilisation et l’opinion des militaires sur les différents moyens de protection individuelle. Un
questionnaire a été proposé aux militaires de différentes unités de l’armée de Terre et 1 315 réponses ont été analysées.
Sur le plan des résultats, 99,5 % des militaires interrogés déclaraient porter des protections auditives lors des tirs en stand
alors que l’absence de protection concernait 8,9 % des militaires lors des tirs en situation opérationnelle. La première
cause d’absence de protection évoquée par les militaires était la difficulté à percevoir l’environnement sonore. C'est
pourquoi les bouchons à atténuation non linéaire sont de plus en plus utilisés : ils permettent de garder une
communication avec l'extérieur tout en étant protégé contre les bruits impulsionnels, mais pas contre les bruits continus.
Un militaire sur six déclarait avoir déjà été victime d’un traumatisme sonore aigu et un sur trois avoir déjà présenté des
acouphènes aigus après un tir malgré le port des protections auditives. Ces antécédents de TSA de même que les
acouphènes occasionnels après tir étaient corrélés aux difficultés de mise en place des protections auditives qui étaient
retrouvées chez plus de 10 % des militaires. C'est pourquoi des protections « moulées sur mesure », adaptées au conduit
auditif pourraient être envisagées pour diminuer l’incidence des traumatismes sonores aigus.
FV sistemler için DSP tabanlı hibrit kontrol yöntemi
Authors: ÜZMUŞ Hasan , GENÇ Naci , ÇELİK Mehmet Ali
Published: April 2023

Güneşten gelen ışınları elektrik enerjisine dönüştüren fotovoltaik (FV) paneller çıkışlarında doğrusal olmayan düşük seviyeli doğru akım (DA) formunda gerilim üretirler. Bu çalışmada, yüksek güçlü uygulamalar için FV panellerin gerilimini regüle etmek amacıyla yükselten tip DA/DA dönüştürücü devresine DSP tabanlı hibrit kontrol yöntemi önerilmiştir. Önerilen bu kontrol yöntemi aynı zamanda değiştir ve gözle maksimum güç noktası izleme (D&G MGNİ) işlevini de içermektedir. Gerilim kontrolü için PI ve akım kontrolü için ortalama kayan kipli (OKK) kontrolcü kullanılmıştır. Önerilen hibrit kontrol yöntemi, D&G MGNİ, PI, OKK kontrolcülerinin arka arkaya seri bağlanmasıyla elde edilmiştir. Önerilen kontrol yöntemi ile FV panel maksimum güç noktasında çalıştırılırken, çıkış gerilimi ve akımı sırasıyla PI ve OKK kontrolcüleri ile kontrol edilmiştir. DA/DA yükselten tip dönüştürücünün giriş kaynağı FV panel olarak modellenmiş ve MATLAB/Simulink benzetim ortamında önerilen hibrit kontrol yöntemi ile kontrol edilmiştir. Önerilen sistem ve kontrolcü için deney düzeneği kurulmuş ve DSP TMS320F28379D kartı vasıtasıyla çıkış gerilimi 200V ve çıkış gücü 400W olan sistemin deneysel sonuçları aktarılmıştır.
Tarihi bir çevrede kent turizminin erişilebilirliğini geliştirmek için mekan dizimine (space syntax) dayalı bir analiz yöntemi
Authors: KUZULUGİL Ali Can , ÜNSAL Ömer , YILDIZ Nalan , AYTATLI Başak
Published: April 2023

Kent merkezleri, geleneksel anlamda yerel ve uluslararası ziyaretçiler için cazibe noktalarıdır. Kentsel alanlar çeşitlilik ve konum açısından odak noktası olabilecek bir dizi turizm ve seyahat akışı sağlamaktadır. Kent içi mekânların anlamlı bütünsellik oluşturmasını sağlayacak en önemli nokta, mekanların ilişkisel yapılarıdır. Kentlerin zamanla yenilenmeleri ve tarihi miras alanlarının insanlar tarafından turizm amaçlı kullanma talepleri, kentin yapısal ve sosyal yapısını geliştirerek kent kimliğini doğru algılanmasını sağlayacaktır.

Çalışmada Erzurum kent merkezindeki tarihi mekânların, fonksiyonellik açısından yapı özellikleri ile mekanların biçimlenme özellikleri arasındaki ilişkilerin karşılaştırmalı olarak incelenmesine olanak sağlayan ve mekanların performansının fiziksel ve alansal biçimden etkileniş hikayesini anlatan Mekan dizimi analiz yöntemi kullanılmıştır. Space Syntax’ın harita ve istatistiksel çizelgeleriyle erişilebilirlik, turistik rota ve insan akışındaki entegrasyon bağlantısına dayanarak, sokak ağı ve işlevsellik performansı değerlendirme amaçlanmıştır. Kentin tarihi mekanlarının olduğu rota üzerindeki cadde-sokak ağı tabanlı kritik noktalar belirlenmiş ve tarihi mekanların mevcut kullanımının, fonksiyonellik, ulaşım ve entegrasyon çekiciliği arasındaki kombinasyonun etkileri tespit edilmiştir. Tarihi dokunun yoğun olduğu kent bölümlerinde yapılı çevre ve şehir arasındaki ilişki ağı çevre, erişim-ulaşım ve sosyal ilişkiler yorumlanmıştır. Sonuçta yabancı turistler yüksek küresel entegrasyon gösteren sokaklarda gezinmeyi tercih ederken, yerel halkın yüksek yerel entegrasyon sergileyen sokakları tercih ettiği belirlenmiştir. Küresel entegrasyonun yüksek olduğu aksların, turistler için çok daha önemli bir rota oluşturduğu ortaya çıkmıştır.
Kısmi seramik kaplı pistonlu buji ateşlemeli motora su enjeksiyonunun etkileri
Authors: CESUR İdris , CELİK Hasan Ali
Published: April 2023

Yanma odasından dışarıya transfer edilen ısı miktarı yanma verimini direkt etkilemektedir. Isı transfer miktarının artması yanma verimini azaltmaktadır. Motorlarda termal kaplama yöntemleri ile ısı transfer miktarı azaltılarak yanma verimi artmaktadır. Fakat yanma odasının tamamının termal malzeme ile kaplanması buji ateşlemeli motorlarda vuruntu temayülünün artmasına ve emisyon değerlerinin kötüleşmesine neden olmaktadır. Vuruntu temayülünün ve emisyon değerlerinin azaltılmasında en etkiyi yöntemlerinden biri de su-buhar enjeksiyon yöntemidir. Su enjeksiyon yöntemi ile motor performans parametrelerinde kötüleşme olmadan emisyon değerleri kayda değer oranlarda azaltılabilmektedir. Çalışmada, motor verimini arttırmak için piston üst yüzeyi ısı rezervi yüksek MgOZrO2 seramik malzeme ile kısmi kaplanmıştır. Kaplamalı motora, anlık yakıt tüketiminin %10, %20 ve %30 kütlesel oranlarında emme manifolduna su püskürtülmüştür. İki yöntem aynı anda kullanılarak performans parametreleri ve egzoz emisyonlarında iyileşmeler elde edilmiştir. TBL pistonlu motorda güç, tork, özgül yakıt sarfiyatı, efektif verim ve HC emisyonları iyileşirken NOx emisyonları artmaktadır. Emme manifolduna su enjeksiyon yapılması durumunda ise performans parametrelerinde kötüleşme olmadan artan NOx emisyonları azalmaktadır. % 20 su püskürtme oranında motor torku ve efektif güçte % 4,1, özgül yakıt sarfiyatında, %3,8 ve efektif verimde %3,9 oranlarında iyileşmeler saptanmıştır. NOx emisyonlarında %30 su püskürtme oranında standart motor verilerine göre %20 oranında azalma elde edilmiştir. Ayrıca %20 su püskürtme oranında HC emisyonlarında % 33’e varan oranlarda azalmalar saptanmıştır.