On the electromagnetic shielding properties of carbon fiber materials

Introduction. Due to the good electrical and thermal properties of carbon, carbon-based materials represent a major trend is various applications, including electromagnetic compatibility. Among carbon-based materials, graphite-impregnated woven fabrics represent a new trend in the field of electromagnetic shielding, with the perspective of being used for protective clothing. The novelty of the proposed work consists in the exhaustive comparative analysis of various carbon-based sample shields by employing both simulation and experimental methods. The selected configurations included a simple graphite plate, a graphite powder strip network, and a graphite-impregnated fabric with 2´2 twill weave. Purpose. The main scope of the analysis is to prove the efficiency of the graphite-impregnated twill woven fabric in the field of electromagnetic shielding. Methods. Two main research methods were employed: simulation and experiment, both following the same protocol: the shield placed in the middle, with the excitation (transmitting antenna) on one side and the measurement / receiving antenna on the other. The experimental stage was thorough, being performed in two different laboratories and by applying the double transverse electromagnetic (TEM) cell method and the shielded box method. Results. A significant difference yielded from the comparison of the simulation and experimental results for the shielding effectiveness, probably due to the fact that the virtual model is an idealized version of the physical one, not taking into account its imperfections. The virtual analysis yielded the graphite plate shield as the most efficient, followed closely by the twill fabric. The graphite strip network had significantly poorer performance compared to the other two shields, probably due to the electrical contact imperfections between the graphite strips and the optical transparency of the shield. The main focus of the analysis was the twill woven graphite-impregnated fabric; therefore, its shielding effectiveness was determined through simulation and experiment. The experimental analysis was performed in two stages in two different electromagnetic compatibility laboratories, by employing the double TEM cell method and the shielded box method, respectively, both methods providing similar results and classifying the shielding performance as good. Practical value. The paper provides an accurate analysis of the graphite-impregnated 2´2 twill woven fabric in terms of electromagnetic shielding effectiveness, by employing both simulation and experimental methods, and comparing its performance to the one other graphite-based shields.Вступ. Завдяки хорошим електричним і тепловим властивостям вуглецю, вуглецевмісні матеріали являють собою основні напрямки у різних застосуваннях, у тому числі в області електромагнітної сумісності, завдяки хорошим екрануючим властивостям. Серед матеріалів на основі вуглецю просочені графітом тканини є новою тенденцією в області електромагнітного екранування з перспективою використання для захисного одягу. Новизна запропонованої роботи полягає у вичерпному порівняльному аналізі різних зразків екранів на основі вуглецю з використанням як моделювання, так і експериментального методів. Вибрані конфігурації включали просту графітову пластину, сітку зі смуг з графітового порошку і просочену графітом тканину з переплетенням саржею 2´2. Ціль. Основною метою аналізу є доказ ефективності саржевого полотна, просоченого графітом, у галузі електромагнітного екранування. Методи. Використовувалися два основних методи дослідження: моделювання та експеримент, обидва слідували одному й тому ж протоколу: екран розташовувався посередині, з збуджуванням (передаючою антеною) з одного боку і вимірювальною/приймальною антеною з іншого. Експериментальний етап був ретельним і проводився у двох різних лабораторіях із застосуванням методу подвійної поперечної електромагнітної (ПЕМ) комірки та методу екранованої скриньки. Результати. Порівняння результатів моделювання та експериментів стосовно ефективності екранування демонструє суттєву відмінність, ймовірно, через те, що віртуальна модель є ідеалізованою версією фізичної, не враховуючи її недосконалості. Віртуальний аналіз показав, що екран із графітових пластин є найбільш ефективним, за ним близько слідує саржева тканина. Мережа з графітових смуг мала значно гірші характеристики порівняно з двома іншими екранами, ймовірно, через недосконалість електричного контакту між графітовими смужками та оптичною прозорістю екрана. Основним предметом аналізу була тканина саржевого переплетення, просочена графітом; тому її ефективність екранування визначалася шляхом моделювання та експерименту. Експериментальний аналіз був виконаний у два етапи у двох різних лабораторіях електромагнітної сумісності з використанням методу подвійної ПЕМ комірки та методу екранованої скриньки, відповідно, обидва методи дали аналогічні результати та визначили характеристики екранування як хороші. Практична цінність. У статті наведено точний аналіз просоченої графітом саржевої тканини 2´2 з точки зору ефективності електромагнітного екранування з використанням як моделювання, так і експериментальних методів, а також порівняння її характеристик з іншими екранами на основі графіту

Ti-Zr-Si-Nb nanocrystalline alloys and metallic glasses: Assessment on the structure, thermal stability, corrosion and mechanical properties

The development of novel Ti-based amorphous or \u3b2-phase nanostructured metallic materials could have significant benefits for implant applications, due to improved corrosion and mechanical characteristics (lower Young's modulus, better wear performance, improved fracture toughness) in comparison to the standardized \u3b1+\u3b2 titanium alloys. Moreover, the devitrification phenomenon, occurring during heating, could contribute to lower input power during additive manufacturing technologies. Ti-based alloy ribbons were obtained by melt-spinning, considering the ultra-fast cooling rates this method can provide. The titanium alloys contain in various proportions Zr, Nb, and Si (Ti60Zr10Si15Nb15, Ti64Zr10Si15Nb11, Ti56Zr10Si15Nb19) in various proportions. These elements were chosen due to their reported biological safety, as in the case of Zr and Nb, and the metallic glass-forming ability and biocompatibility of Si. The morphology and chemical composition were analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy, while the structural features (crystallinity, phase attribution after devitrification (after heat treatment)) were assessed by X-ray diffraction. Some of the mechanical properties (hardness, Young's modulus) were assessed by instrumented indentation. The thermal stability and crystallization temperatures were measured by differential thermal analysis. High-intensity exothermal peaks were observed during heating of melt-spun ribbons. The corrosion behavior was assessed by electrocorrosion tests. The results show the potential of these alloys to be used as materials for biomedical applications

Plasma-wall interaction studies within the EUROfusion consortium: Progress on plasma-facing components development and qualification

This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, and by modelling codes that simulate edge-plasma conditions and the plasma-material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.European Commission; Consortium for Ocean Leadership 633053; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Новый подход к исследованию кинематики и динамики планетарных передач 1DOF

The paper is presenting a general method to establish rotational speeds on central elements of 1DOF planetary transmissions, based on the structure of planetary groups. Relationships are all depending on kinematics of the involved planetary units. The paper is also presenting calculus procedures for developing software for kinematics analysis of generalized planetary transmissions, and a graphic representation of rotational speeds on two-planetary groups.Lucrarea prezintă o metodică generalizată pentru determinarea vitezelor unghiulare ale elementelor centrale ale transmisiilor planetare monomobile, reprezentate ca grupuri planetare. Relaţiile de calcul sunt stabilite în funcţie doar de rapoartele de transmitere interioare ale unităţilor planetare componente. Lucrarea prezintă, de asemenea, proceduri specifice de calcul utile în dezvoltarea unui program de calcul pentru analiza cinematică a transmisiilor planetare generalizate. Rezultatele calculului sunt prezentate în manieră grafică.L’article presente une nouvelle méthode générale d’établissment les viteses angulaires des élémentes composantes d’un group planetaire avec une degrée de liberté. Ils sont dependent seulement de le kinematic du l’unite planetaire composantes. Des procedures de calcul pour dévéloper un logiciel pour la cinématique des transmissions planétaires sont établis, et les resultats sont afficher grafiquement.В работе приведена общая методика определения угловых скоростей центральных элементов одноподвижных планетарных передач, представленные как планетарные группы. Расчётные зависимости определены в функции только внутренних передаточных отношений планетарных единиц. В работе также приведены специфические расчётные методики для разработки расчётной программы для кинематического анализа планетарных передач. Результаты расчётов приведены в графической форме

Performing Counter-Hegemonic Common(s) Senses: Rearticulating Democracy, Community and Forests in Puerto Rico

Political ecologists have developed scathing analyses of capitalism’s tendency for enclosure and dispossession of the commons. In this context commons are analyzed as a force to resist neo-liberalism, a main site of conflict over dispossession, and a source of alternatives to capitalism. In this paper we elaborate a view of the commons as the material and symbolic terrain where performative re-articulation of common(s) senses can potentially enact counter-hegemonic socio-ecological configurations. Expressly drawing on the concepts of hegemony, “common-senses” (inspired by Antonio Gramsci) and “performativity” (developed by Judith Butler), we argue that counter-hegemony is performed through everyday practices that rearticulate existing common senses about commons. Commoning is a set of processes/relations enacted to challenge capitalist hegemony and build more just/sustainable societies insofar as it transforms and rearranges common senses in/through praxis. The paper draws on the experience of an anti-mining movement of Casa Pueblo in Puerto Rico, which for the last 35+ years has been developing a project self-described as autogestion. The discussion pays special attention to Casa Pueblo’s praxis and discourses to investigate how they rearticulate common senses with regard to nature, community and democracy, as well as their implications for counter-hegemonic politics

Aspects of innovative process on creative problem solving

International audienc

Возможности сохранения красных вин

În lucrarea dată sunt prezentate rezultatele experienţelor în care s-a stabilit influenţa metodei de păstrare a vinurilor roşii Cabernet-Sauvignon şi Merlot asupra complexului fenolic şi indicilor cromatici. Vinurile au fost păstrate în butelie, talaş de stejar moldovenesc şi francez, precum şi în butoi de stejar pe o durată de 90 zile.This article presents the results of experiments that established the influence of the storage method of Cabernet Sauvignon and Merlot red wines on the phenolic complex and chromatic indices. The wines were kept in the bottle, moldavian and french oak shavings and oak barrel for a period of 90 days.Cet article présente les résultats d’expériences qui ont établi l’influence de la méthode de stockage des vins rouges Cabernet Sauvignon et Merlot sur les complexes phénoliques et indices chromatiques. Les vins ont été conservés dans les bouteilles, sur des copeaux de chêne français et moldaves et en fûts de chêne pendant une période de 90 jours.В данной работе представлены результаты исследований влияния способ хранения на показателей цветности и изменения фенольных веществ вин из сортов винограда Каберне Совиньон и Мерло. Эти вина хранили в бутылках, молдавские и французские стручки дуба, а также в дубовой бочке в течение 90 дней

Aspects of innovative process on creative problem solving

International audienc