Articoli di riviste sul tema "Certification de durabilité"
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Piketty, Marie-Gabrielle, Maria-Célia Martins De Souza e Isabel Garcia Drigo. "Certification environnementale et durabilité au Brésil". Économie rurale, n. 303-304-305 (1 giugno 2008): 169–83. http://dx.doi.org/10.4000/economierurale.674.
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DI ROBERTO, Hadrien, Carolina MILHORANCE, Ndèye SOKHNA DIENG e Elsa SANIAL. "L’agroforesterie en contexte post-forestier : perspectives et controverses d’une mise à l’agenda politique en Côte d’Ivoire". BOIS & FORETS DES TROPIQUES 356 (4 settembre 2023): 81–91. http://dx.doi.org/10.19182/bft2023.356.a37121.
Abstract (sommario):
En Côte d’Ivoire, l’agroforesterie devient une notion incontournable après une déforestation massive pour les cultures de plantation. Depuis les années 2010, le terme se généralise dans le vocabulaire politique, les normes internationales de durabilité et la communication des entreprises chocolatières. Cette note examine comment l'agroforesterie s’est imposée dans l'agenda politique ivoirien. Adoptant une approche compréhensive et à partir d’une soixantaine d’entretiens et des documents politiques, elle analyse la manière dont la notion d’agroforesterie est mobilisée en Côte d’Ivoire, les instruments de sa promotion et les controverses qu’elle suscite. D’abord, ce travail montre que la mise à l’agenda de l’agroforesterie en Côte d’Ivoire se fait suivant des canaux pluriels. Différents instruments de promotion de l’agroforesterie se côtoient, tels que les normes de certification privée, la norme africaine régionale de durabilité pour le cacao, les paiements pour services environnementaux ou encore un dispositif national dit « Agro-Forêt », issu du nouveau Code forestier. Ensuite, malgré le consensus sur la promotion de l'agroforesterie, sa définition large permet à des acteurs aux intérêts divergents de s'approprier le concept. Ce travail met par ailleurs en évidence la pluralité des objectifs et des perspectives que recouvre la notion en Côte d’Ivoire. Il identifie ainsi des controverses concernant les critères du système agroforestier, sa finalité, la place des agriculteurs, l’échelle d’analyse et la temporalité à considérer. En définitive, cette note contribue à expliciter les traductions politiques plurielles d’une notion issue des sciences. Les liens complexes entre les recherches biophysiques et la pratique politique soulignent l'importance de prendre en compte cette interface pour une meilleure conception de l'agroforesterie et une transition efficace.
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Ruf, François. "Les standards dits durables appauvrissent-ils les planteurs de cacao ? Interactions entre déforestation en Côte d’Ivoire et au Libéria, crédit à l’achat d’engrais et baisse des cours". Cahiers Agricultures 30 (2021): 38. http://dx.doi.org/10.1051/cagri/2021024.
Abstract (sommario):
Pendant des siècles, combinés avec le travail de migrants, la forêt et la rente forêt ont été les principaux facteurs de production du cacao. C’est le modèle universel du cacao, qui a fait de la Côte d’Ivoire le premier producteur mondial. Mais le niveau de déforestation est tel qu’une partie des planteurs doivent trouver des alternatives à la rente forêt, notamment l’engrais minéral. Cet intrant chimique est de fait un facteur d’amélioration des rendements et a priori des revenus. Cependant, si la consommation d’engrais chimique est poussée par le « système », composé des Transnational Corporations (TNC) du cacao, des coopératives, des agences de crédit, des organisations non gouvernementales internationales et des labels de cacao dit « durables », n’y a-t-il pas danger d’effets inverses : contribution à l’excès d’offre de cacao, baisse du cours mondial, endettement et appauvrissement des planteurs ? À partir de trois enquêtes auprès de 150 à 250 planteurs entre 2013 et 2017, d’une enquête auprès de 41 coopératives en 2017 et d’un suivi des prix du cacao et de l’engrais sur 30 ans, l’étude aborde le rôle du prix relatif cacao/engrais et du crédit sur la consommation d’engrais, et leur impact sur la chute du cours du cacao en 2016–2017. L’impact est certain, même si le processus d’expansion cacaoyère par le binôme migration-déforestation reste le facteur essentiel de la hausse de l’offre et de la chute du cours. Le discours selon lequel les gains de rendement vont créer un « cacao durable » et dissuader les planteurs de défricher les forêts reste un mythe. Les migrations continuent aux dépens des toutes dernières forêts classées du pays, à l’est vers Abengourou, à l’ouest vers Blolequin, Man et Touba. Là encore, en dépit de leur communication sur la durabilité, les certifications ont totalement échoué : le cacao de Côte d’Ivoire dépend encore beaucoup de la déforestation. Enfin, de l’autre côté du fleuve Cavally, la grande forêt dense du Libéria disparaît à son tour, sur la voie d’un nouveau boom du cacao. Même si les responsabilités sont partagées avec les politiques publiques, que reste-t-il de « durable » dans la certification et les actions de la majorité des TNC ? Le fossé entre leur communication virtuelle et la réalité n’a jamais été aussi grand.
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VEISSIER, I., R. BOTREAU e P. PERNY. "Évaluation multicritère appliquée au bien-être des animaux en ferme ou à l’abattoir : difficultés et solutions du projet Welfare Quality®". INRAE Productions Animales 23, n. 3 (14 settembre 2010): 269–84. http://dx.doi.org/10.20870/productions-animales.2010.23.3.3308.
Abstract (sommario):
Face au développement en Europe de programmes de certification d’élevages mettant en avant le respect du bien-être animal, le projet Welfare Quality® a proposé à l’Union Européenne d’établir un modèle d’évaluation globale des exploitations (fermes ou abattoirs) au regard du bien-être des animaux. Ce modèle repose sur une évaluation multicritère dans laquelle 12 critères de bien-être, regroupés en 4 principes, ont été définis. Après avoir identifié les mesures nécessaires pour vérifier qu’une exploitation est conforme aux différents critères, le modèle a été progressivement construit. Il aboutit à un classement des exploitations en quatre catégories reflétant le niveau de bien-être (d’excellent à très faible). Pour ce faire, des méthodes multicritères ont été utilisées, évitant ainsi les écueils d’une agrégation naïve de l’information (comme les sommes pondérées qui autorisent les pleines compensations entre critères, ce qui n’est pas compatible avec le concept de bien-être). Différentes personnes (chercheurs en sciences animales ou sociales, porteurs d’enjeux) ont été consultées au moyen de jeux de données virtuelles sur lesquelles elles devaient donner une appréciation. Le modèle a été développé et paramétré afin de refléter ces appréciations. Une analyse a posteriori des résultats produits montre que le modèle accorde la priorité aux animaux en moins bon état tout en tenant compte de l’état moyen du troupeau, et qu’il limite fortement les compensations entre critères. Cet exemple montre qu’en suivant cette méthodologie rigoureuse, il est possible d’aider l’évaluation d’un concept multidimensionnel, même si cet exercice comporte des choix de valeurs qu’il convient d’expliciter et de modéliser. La méthodologie suivie pour construire ce modèle d’évaluation du bien-être peut être transposée pour évaluer d’autres concepts multidimensionnels comme la durabilité des systèmes de production.
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Molent, L., e R. Singh. "Using the lead crack framework to reduce durability test duration". Aeronautical Journal 124, n. 1276 (24 settembre 2019): 814–20. http://dx.doi.org/10.1017/aer.2019.73.
Abstract (sommario):
ABSTRACTAircraft full-scale fatigue tests are expensive and time-consuming to conduct but are a critical item on the certification path of any aircraft design or modification. This paper outlines a proposal that trades cycling hours for increased detail in the teardown of a metallic test article. A method for determining the equivalent demonstrated crack size (and crack growth curve) at the mandated test life utilising the lead crack framework is demonstrated. It is considered that the test duration can be significantly reduced, whilst still achieving all the desired outcomes of a certification program.
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Jones, Rhys, Daren Peng, John G. Michopoulos e Anthony J. Kinloch. "Requirements and Variability Affecting the Durability of Bonded Joints". Materials 13, n. 6 (23 marzo 2020): 1468. http://dx.doi.org/10.3390/ma13061468.
Abstract (sommario):
This paper firstly reveals that when assessing if a bonded joint meets the certification requirements inherent in MIL-STD-1530D and the US Joint Services Standard JSSG2006 it is necessary to ensure that: (a) There is no yielding at all in the adhesive layer at 115% of design limit load (DLL), and (b) that the joint must be able to withstand design ultimate load (DUL). Secondly, it is revealed that fatigue crack growth in both nano-reinforced epoxies, and structural adhesives can be captured using the Hartman–Schijve crack growth equation, and that the scatter in crack growth in adhesives can be modelled by allowing for variability in the fatigue threshold. Thirdly, a methodology was established for estimating a valid upper-bound curve, for cohesive failure in the adhesive, which encompasses all the experimental data and provides a conservative fatigue crack growth curve. Finally, it is shown that this upper-bound curve can be used to (a) compare and characterise structural adhesives, (b) determine/assess a “no growth” design (if required), (c) assess if a disbond in an in-service aircraft will grow and (d) to design and life in-service adhesively-bonded joints in accordance with the slow-growth approach contained in the United States Air Force (USAF) certification standard MIL-STD-1530D.
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Chowdhury, Nabil, Wing Kong Chiu e John Wang. "A Review of Damage Tolerant Design, Certification and Repair in Metals Compared to Composite Materials". Advanced Materials Research 891-892 (marzo 2014): 1597–602. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1597.
Abstract (sommario):
A review of some of the various fatigue models introduced over the years for both metallic materials, in particular aluminium alloys followed by fatigue and durability concerns associated with composite materials. The move towards light weight and high stiffness structures that have good fatigue durability and corrosion resistance has led to the rapid move from metal structures to composite structures. With this brings the added concern of certifying new components as the damage mechanisms and failure modes in metals differ significantly than composite materials such as carbon fiber reinforced polymers (CFRP). The certification philosophy for composites must meet the same structural integrity, safety and durability requirements as that of metals. Hence this is where the challenge now lies. Substantial work has been conducted in the reparability of composite structures through bonding using various adherend thicknesses and joint types and has been shown to have higher durability than mechanically fastened repairs for thin adherends however these are currently unacceptable repair methods as they cannot be certified. Repairs are designed on the basis that the repair efficiency can be predicted and should be designed conservatively with respect to the various failure modes and include the surrounding structure.
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Abdi, F., Y. Xue, M. Garg, B. Farahmand, J. Housner e K. Nikbin. "An analysis approach toward FAA certification for damage tolerance of aircraft components". Aeronautical Journal 118, n. 1200 (febbraio 2014): 181–96. http://dx.doi.org/10.1017/s0001924000009064.
Abstract (sommario):
Abstract This paper presents a novel analysis approach by considering multiple crack interaction in achieving FAA certification for durability and damage tolerance of exterior attachment installations on an aircraft fuselage according to FAA policy on Certification by Analysis-Supported-by-Test (CAST). Durability and damage tolerance evaluation of an aircraft component requires assessment of damage initiation and fatigue crack propagations under service loading, which consists of complex loading types, paths and variable amplitudes. Both simulation and service experience showed that multiple cracks developed in the fuselage skin and doublers that are made of wrought aluminum alloys. Progressive failure analysis (PFA) tool was used to simulate the fatigue damage initiation life using a scale-down stress-life property. A virtual crack closure technique (VCCT) was implemented to evaluate fatigue crack growth with interactions between cracks from different parts in a component, which preserves conservativeness. The fatigue crack growth data is obtained uniquely from an analytical extension of fatigue crack growth data of thin aluminum sheet. Fatigue crack growth analysis showed that only a few initiated cracks propagated steadily before a crack became visible under inspection, which was validated by comparison to service history. Eventually one crack became dominate in the fracturing process thereby setting an inspection time. Analysis also showed that fatigue damage state in the components at the designed operational life will not exceed the static safety requirements. Therefore, FAA accepted the damage tolerance analysis and the aircraft retained certification with no need for repair.
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Peng, Daren, Rhys Jones, Andrew S. M. Ang, Victor Champagne, Aaron Birt e Alex Michelson. "A Numerical Study into the Effect of Machining on the Interaction between Surface Roughness and Surface Breaking Defects on the Durability of WAAM Ti-6Al-4V Parts". Metals 12, n. 7 (29 giugno 2022): 1121. http://dx.doi.org/10.3390/met12071121.
Abstract (sommario):
The airworthiness certification of military aircraft requires a durability analysis be performed using linear elastic fracture mechanics (LEFM). Furthermore, such analyses need to use a valid small crack growth equation. This paper focuses on the effect of rough surfaces and the effect of machining the surface on the durability of AM parts using LEFM and a valid small crack growth equation for the material. To this end, this paper analyses the effect of surface roughness on wire and arc additively manufactured (WAAM) Ti-6Al-4V titanium parts and the effect of machining on the durability of a part. The analysis reveals that the life of the component is a relatively strong function of the degree of surface roughness, and that the durability of a specimen is a strong function of the local radius of the curvature of the trough. It also appears that surfaces with tall narrow roughness will not overly benefit from partial machining of the surface.
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Peng, Daren, Victor K. Champagne, Andrew S. M. Ang, Aaron Birt, Alex Michelson, Sam Pinches e Rhys Jones. "Computing the Durability of WAAM 18Ni-250 Maraging Steel Specimens with Surface Breaking Porosity". Crystals 13, n. 3 (3 marzo 2023): 443. http://dx.doi.org/10.3390/cryst13030443.
Abstract (sommario):
The durability assessment of additively manufactured parts needs to account for both surface-breaking material discontinuities and surface-breaking porosity and how these material discontinuities interact with parts that have been left in the as-built state. Furthermore, to be consistent with the airworthiness standards associated with the certification of metallic parts on military aircraft the durability analysis must be able to predict crack growth, as distinct from using a crack growth analysis in which parameters are adjusted so as to match measured data. To partially address this, the authors recently showed how the durability of wire arc additively manufactured (WAAM) 18Ni-250 maraging steel specimens, where failure was due to the interaction of small surface-breaking cracks with surface roughness, could be predicted using the Hartman–Schijve variant of the NASGRO crack growth equation. This paper illustrates how the same equation, with the same material parameters, can be used to predict the durability of a specimen where failure is due to surface-breaking porosity.
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Kundu, Sudip, Rhys Jones, Daren Peng, Neil Matthews, Alankar Alankar, Singh R. K. Raman e Pu Huang. "Review of Requirements for the Durability and Damage Tolerance Certification of Additively Manufactured Aircraft Structural Parts and AM Repairs". Materials 13, n. 6 (15 marzo 2020): 1341. http://dx.doi.org/10.3390/ma13061341.
Abstract (sommario):
The USAF requirements for the durability and damage tolerance certification for additively manufactured (AM) aircraft structural parts, which are detailed in Structures Bulletin EZ-19-01, raise a number of new and, as yet, unanswered questions. The present paper attempts to address three questions: How to perform a fracture mechanics-based analysis of crack growth in an AM part so as to account for the residual stresses, how to perform a fracture mechanics-based durability analysis of a cold spray repair so as to account for both the induced residual stresses and the presence of multiple co-located cracks, and how to perform a fracture mechanics-based durability analysis of an AM part so as to account for the presence of multiple collocated surface braking cracks. In this context, the present paper reveals the potential of the Hartman–Schijve variant of the NASGRO crack growth equation to accurately predict the growth of each of the individual (collocated) cracks that arose in a cold spray-repaired specimen and in a specimen from a crack that nucleated and grew from a rough surface.
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Zbrowski, Andrzej, e Krzysztof Matecki. "Test Stand for Durability Tests of Rotating Elements of Office Chairs". Solid State Phenomena 223 (novembre 2014): 155–62. http://dx.doi.org/10.4028/www.scientific.net/ssp.223.155.
Abstract (sommario):
This paper presents the purpose, concept, principles of functioning, design and construction of a stand intended for testing the durability of rotational elements of office chairs. It shows the use of the stand for certification tests in accordance with the PN-EN 1335:2009 standard. It also discusses how tests on swivelling and the durability of wheels and the base of office chairs should be conducted using the developed stand. The authors present test conditions and discuss the instrumentation necessary to induce static loads during the investigations. They also identify the possibilities to perform other tests on the stand by introducing to the existing research instruments additional instrumentation necessary from the point of view of the above listed standard. The possibility of adjusting the stand to the prospective changes in normative requirements and the needs of individual users are also described.
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Hostev, Yuriy, Lev Rumiantsev e Tetyana Kostrulova. "QUALITY CONTROL OF HORIZONTAL ROAD MARKING APPLICATION DURING CERTIFICATION OF MARKING MACHINES". Avtoshliakhovyk Ukrayiny, n. 3 (259) ’ 2019 (17 ottobre 2019): 24–29. http://dx.doi.org/10.33868/0365-8392-2019-3-259-24-29.
Abstract (sommario):
Horizontal road marking along with road signs is an essential factor that ensures road safety. The quality of road markings largely depends on the quality of the application. In today’s, for road marking are used road marking machines. They are complex high-performance automated units requiring highly professional operators. Stink to classify for the way of marking, design of the running gear, base machine, type of drive, productivity and the most important signs. The article describes the principles of the operation of marking machines and the main technical characteristics of machines from leading manufacturers: GRACO, SТiM, Hofmann. When applying road marking, special attention should be paid to the use of certified materials and certified equipment. The results of measuring the geometric and lighting indicators of horizontal road marking are presented. During certification, marking is applied with a marking machine. During the application, the thickness of the liquid paint layer is determined by a calibrated comb. To control the lighting technical characteristics of road marking – whiteness, retroreflectivity (Rl) and brightness (Qd) coefficients, a ZRM 1021 reflectometer and a ZRM 1013 retroreflectometer are used. Geometric indicators were measured with a tape measure. The table of certification results of the Line Lazer IV 3900 machine is shown. Similar indicators were obtained during certification of the machines of Hofmann, Combizet Gruen, RoadLazer, etc. Deviations from the road marking indicators declared by the manufacturer are not observed for 3 years. All marking performed by verified marking machines meets the requirements of current regulations. Keywords: certification of machines, durability of marking, retroreflectivity, accuracy of application, brightness.
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Mamun, Muhammad Ziaulhaq, e Sazidur Rahman Talukder. "University Students’ Perception of Quality: A Case of Bangladesh". International Journal of Research and Innovation in Social Science VIII, IIIs (2024): 161–81. http://dx.doi.org/10.47772/ijriss.2024.803011s.
Abstract (sommario):
This paper explored the quality perception of university students of Bangladesh in terms of 57 quality dimensions. A total of 258 responses from both public and private universities with different demographics are considered using non-probability convenient sampling technique. The responses are found reliable and valid. The most important quality dimensions observed by the respondents are value for money, completeness, privacy, serviceability, performance, durability, accurate quantity, reliability, taste, sound, easy identification, and conformance. The very close to highly agreed attributes are quality certification, ease of use, responsiveness, timeliness, hygienic/cleanliness, accuracy, easy installation, competency, and accessibility and convenience. On the other hand, the least agreed quality dimensions as perceived by the respondents are appealing facilities, packaging/look, prestige, financial facilities, foreign good, advertisement, loyalty program, financially sound brand, CSR, celebrity endorsement. Of the 29 quality attributes of goods, the study identified good value, performance, serviceability, durability, reliability, sound, easy identification, conformance, taste, ease of use, easy set-up as the most important quality dimensions. Interestingly the students give less emphasis on natural and cognitive based quality attributes. On the other hand, of the 18 service quality attributes, the respondents found completeness, accuracy, cleanliness, timeliness, responsiveness, and accessibility & convenience as most important quality attributes. Further, of the ten quality constructs common to both service and manufacturing items the respondents identified privacy of information and quality certification as the most important. On the other extreme the least agreeable attributes are financially sound companies, CSR activity, and celebrity endorsement. Demography and ideography wise no significant difference is observed in the study.
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Podstawka, Michal, Vladimír Snop, Petr Bělský e Kristýna Kutiová. "Non-destructive Inspection of Composite Aileron during Fatigue Test". MATEC Web of Conferences 349 (2021): 03016. http://dx.doi.org/10.1051/matecconf/202134903016.
Abstract (sommario):
The operational safety and reliability of an airplane must be an integral part of its design. The use of suitable materials that pass material certification tests is very important for a new aircraft design. The next part is testing specific samples, sub-components, and components such as the aileron. The paper deals with a non-destructive evaluation of composite primary structural part fatigue tests in accordance with damage tolerance philosophy considering impact damage presence. NDT methods such as visual, eddy current, and ultrasonic testing included phased array technique, are used for the inspections. A schedule of inspections was created, and structural durability was verified.
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Jones, Rhys, Calvin Rans, Athanasios P. Iliopoulos, John G. Michopoulos, Nam Phan e Daren Peng. "Modelling the Variability and the Anisotropic Behaviour of Crack Growth in SLM Ti-6Al-4V". Materials 14, n. 6 (13 marzo 2021): 1400. http://dx.doi.org/10.3390/ma14061400.
Abstract (sommario):
The United States Air Force (USAF) Guidelines for the Durability and Damage Tolerance (DADT) certification of Additive Manufactured (AM) parts states that the most difficult challenge for the certification of an AM part is to establish an accurate prediction of its DADT. How to address this challenge is the focus of the present paper. To this end this paper examines the variability in crack growth in tests on additively manufactured (AM) Ti-6Al-4V specimens built using selective layer melting (SLM). One series of tests analysed involves thirty single edge notch tension specimens with five build orientations and two different post heat treatments. The other test program analysed involved ASTM standard single edge notch specimens with three different build directions. The results of this study highlight the ability of the Hartman–Schijve crack growth equation to capture the variability and the anisotropic behaviour of crack growth in SLM Ti-6Al-4V. It is thus shown that, despite the large variability in crack growth, the intrinsic crack growth equation remains unchanged and that the variability and the anisotropic nature of crack growth in this test program is captured by allowing for changes in both the fatigue threshold and the cyclic fracture toughness.
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ORIFICI, ADRIAN C., RODNEY S. THOMSON, RICHARD DEGENHARDT, CHIARA BISAGNI e JAVID BAYANDOR. "AN ANALYSIS TOOL FOR DESIGN AND CERTIFICATION OF POSTBUCKLING COMPOSITE AEROSPACE STRUCTURES". International Journal of Structural Stability and Dynamics 10, n. 04 (ottobre 2010): 669–81. http://dx.doi.org/10.1142/s0219455410003671.
Abstract (sommario):
In aerospace, carbon-fiber-reinforced polymer (CFRP) composites and postbuckling skin-stiffened structures are key technologies that have been used to improve structural efficiency. However, the application of composite postbuckling structures in aircraft has been limited due to concerns related to both the durability of composite structures and the accuracy of design tools. In this work, a finite element analysis tool for design and certification of aerospace structures is presented, which predicts collapse by taking the critical damage mechanisms into account. The tool incorporates a global–local analysis technique for predicting interlaminar damage initiation, and degradation models to capture the growth of a pre-existing interlaminar damage region, such as a delamination or skin–stiffener debond, and in-plane ply damage mechanisms such as fiber fracture and matrix cracking. The analysis tool has been applied to single- and multistiffener fuselage-representative composite panels, in both intact and predamaged configurations. This has been performed in a design context, in which panel configurations are selected based on their suitability for experimental testing, and in an analysis context for comparison with experimental results as being representative of aircraft certification studies. For all cases, the tool was capable of accurately capturing the key damage mechanisms contributing to final structural collapse, and suitable for the design of next-generation composite aerospace structures.
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Bodnar, Larysa, Serhii Zavhorodnii, Serhii Stepanov e Vitalii Yastrubinetskyi. "ANALYSIS OF DURABILITY OF REINFORCED CONCRETE STRUCTURES OF BRIDGES ACCORDING TO THEIR TYPICAL DESIGNS". Avtoshliakhovyk Ukrayiny 264, n. 4 (21 dicembre 2020): 58–63. http://dx.doi.org/10.33868/0365-8392-2020-4-264-58-63.
Abstract (sommario):
Thousands of bridges built in the 20th century are operated on Ukrainian roads. In the limited funding of the road industry of Ukraine, the age of highway bridges is constantly increasing, the number of defects in structures is growing. The largest number of defects is concentrated in the bridge spans. The main part of the bridge spans consists of prefabricated reinforced concrete beams, manufactured in factories of reinforced concrete structures according to standard designs developed in the middle of the last century. As a result of long-term operation of bridges, the shortcomings of these designs which reduce the service life of bridge spans and bridges in general are revealed. The systematic approach is required to study this process. The Analytical Expert Bridge Management System (AESUM) operates in the Ukravtodor system. This software complex accumulates all the information on the results of inspections (certification) of bridges on public roads. The special module AESUM – a database of standard designs of bridge spans which is constantly updated was developed to make decisions on repair works taking into account the features of structures on standard designs, to store this information in a single complex, in electronic form. Standard designs of reinforced concrete bridge spans built and operated on the roads of Ukraine are considered, and a comparative analysis of the features of these designs is performed taking into account the impact on the safety of bridge operation, their main features and shortcomings are given. The concept of rank of the standard design on durability is entered. A formula for estimating the durability of bridge span of a standard design using this concept is proposed. The analysis of durability of bridge span is performed. A number of problematic standard designs have been identified. Keywords: road bridge, standard designs, durability.
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Strang, Marcus, Paola Leardini, Arianna Brambilla e Eugenia Gasparri. "Mass Timber Envelopes in Passivhaus Buildings: Designing for Moisture Safety in Hot and Humid Australian Climates". Buildings 11, n. 10 (14 ottobre 2021): 478. http://dx.doi.org/10.3390/buildings11100478.
Abstract (sommario):
The uptake of buildings employing cross-laminated timber (CLT) assemblies and designed to Passivhaus standard has accelerated internationally over the past two decades due to several factors including responses to the climate crisis by decarbonising the building stock. Structural CLT technology and the Passivhaus certification both show measurable benefits in reducing energy consumption, while contributing to durability and indoor comfort. However, there is a general lack of evidence to support a fast uptake of these technologies in Australia. This paper responds to the compelling need of providing quantitative data and adoption strategies; it explores their combined application as a potential pathway for climate-appropriate design of energy-efficient and durable mass timber envelope solutions for subtropical and tropical Australian climates. Hygrothermal risk assessments of interstitial condensation and mould growth of CLT wall assemblies inform best-practice design of mass timber buildings in hot and humid climates. This research found that the durability of mass timber buildings located in hot and humid climates may benefit from implementing the Passivhaus standard to manage interior conditions. The findings also suggested that climate-specific design of the wall assembly is critical for mass timber buildings, in conjunction with excellent stormwater management practices during construction and corrosion protection for metallic fasteners.
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Chowdhury, Nabil, Wing Kong Chiu e John Wang. "Review on the Fatigue of Composite Hybrid Joints Used in Aircraft Structures". Advanced Materials Research 891-892 (marzo 2014): 1591–96. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1591.
Abstract (sommario):
The use of composite materials as a replacement for commonly used metals such as aluminium and steel are increasing in the engineering industry, particularly in the aerospace sector. The move towards light weight and high stiffness structures that have good fatigue durability and corrosion resistance has led to the rapid move from metal to composites. This change allows for further flexibility in design and fabrication of various components and joints. There are three main categories of joints used in composite materials – mechanically fastened joints, adhesively bonded joints and the combination of the two called hybrid joints. In order to adequately understand the effectiveness of these joints, substantial testing and validation is required, particularly in the use of hybrid joints for real life applications. Static testing, load distribution and parametric studies of hybrid joints have been investigated by various researchers; however further work is still required in understanding the durability and fatigue of hybrid joints and ensuring that both the adhesive and mechanical fasteners can work together effectively in producing an optimum joint. Mechanical fastening alone in composite laminates is not a preferred joining method as they create high stress concentrations around the fastener holes. Adhesive bonding although has numerous benefits it is difficult to detect the bond defect particularly in cases where weak bonds can occur during applications and it is sensitive towards the environmental conditions. Thus hybrid joints are seen arguably as being more effective in joining composite components together and offer greater residual strength. Hence the performance, strength and long-term durability of these joints need to be further investigated and be applied to practical situations whilst assisting in repair certification.
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Moroney, Patrick D., e Amrit Shankar Verma. "Durability and Damage Tolerance Analysis Approaches for Wind Turbine Blade Trailing Edge Life Prediction: A Technical Review". Energies 16, n. 24 (6 dicembre 2023): 7934. http://dx.doi.org/10.3390/en16247934.
Abstract (sommario):
The size of wind turbine blades is increasing rapidly, and they are being installed in remote offshore locations. Consequently, it is essential to focus on improving the design and maintenance procedures in the blade industry to meet the growing demand. Of particular concern is the long-term operational performance of the wind turbine blade trailing edge. In this paper, we discuss the application of durability and damage tolerance analysis (DADTA) approaches to trailing edge service life prediction. DADTA is mandated in the aerospace sector to support airworthiness certification and to provide an updated life prediction of the structure based on the different stages of their service life. The DADTA framework has two main parts: durability and damage tolerance analysis. The durability part uses a structural fatigue approach based on a damage accumulation method during the initial design phase to predict the lifespan of a structure without defects. On the other hand, the damage tolerance analysis part uses a fracture mechanics approach and a damage growth method to update the lifespan prediction of a structure during the operation stages. This is achieved by utilizing sensors and inspection data as inputs while the structure is in service. Both these methods are comprehensive and have merits; however, their broad adoption in the wind turbine blade industry is still lacking. The current paper provides an extensive review of these methods and shows how these can be applied to the wind turbine blade industry, specifically for predicting the structural design life of the trailing edge of composite wind turbine blades. The review includes (a) defining wind turbine trailing edge failure modes, (b) trailing edge design procedures, and (c) a detailed discussion of the application of durability and damage tolerance analysis for trailing edge life prediction. Overall, this review paper would be of special interest to blade designers and would guide researchers and engineers interested in life prediction methodologies based on DADTA approaches for wind turbine blades.
22
Lappo, I., Y. Dobryshkin, M. Herashchenko e О. Chervotoka. "PERSPECTIVE WAYS OF DEVELOPMENT OF THE LABORATORY TESTING FACILITIES OF THE ARMED FORCES OF UKRAINE". Наукові праці Державного науково-дослідного інституту випробувань і сертифікації озброєння та військової техніки, n. 3 (28 maggio 2020): 67–76. http://dx.doi.org/10.37701/dndivsovt.3.2020.09.
Abstract (sommario):
The world practice of creating and modernizing specimens of armament and military equipment envisages carrying out numerous tests, checks and evaluations of the current technical conditions throughout the life cycle.
The task of organizing and carrying out of tests, in particular mechanical, electrical and climatic, at the State Scientific Research Institute of Armament and Military Equipment Testing and Certification is entrusted to the scientific research laboratory that is a part of the scientific and technical complex of measurements of the Institute. Currently, the laboratory is not fully equipped with modern testing equipment. Therefore, the task of justification of the ways of development and providing the laboratory with test equipment for conducting mechanical, electrical and climatic tests of armament and military equipment specimens is urgent.
The purpose of the article is to determine the perspective ways of development of the laboratory-testing facilities of the State Scientific Research Institute of Armament and Military Equipment Testing and Certification taking into account the modern development of armament and military equipment specimens.
During the research general scientific methods of processing and systematization of information, in particular system analysis and synthesis of organizational and technical systems were applied.
The peculiarities of the organizing and conducting mechanical, electrical and climatic tests at the enterprises of the defense-industrial complex of Ukraine were analyzed.
It was established that the basis of testing, in addition to legislative acts and technological normative documents, is the availability of a modern laboratory testing base, since without the means of measurement and testing it is impossible to ascertain the stability, sustainability and durability of armament and military equipment specimens to the influence of external factors.
The proposals for the purchase of the test equipment for ensuring tests in the direction of mechanical, electrical and climatic tests of State Scientific Research Institute of Armament and Military Equipment Testing and Certification are given.
23
Buson, Márcio, Humberto Varum e Marco Antônio Rezende. "First Impressions on Three-Dimensional Printing with Earth-Based Mortar at the Faculty of Engineering of the University of Porto". Buildings 14, n. 2 (23 gennaio 2024): 312. http://dx.doi.org/10.3390/buildings14020312.
Abstract (sommario):
Three-dimensional (3D) printing with earth-based mortar is still under development and faces challenges. Optimising the mortar mixture, improving structural strength, determining the relationship between the printing speed and the amount of extruded material, and ensuring long-term durability are areas that are being refined. Additionally, regulatory and certification issues must also be considered to ensure the safety and compliance of 3D printed structures. This paper presents for discussion the records, analyses, studies, and considerations regarding initial initiatives involving 3D printing with the extrusion of earth-based mortar developed at the Faculty of Engineering of the University of Porto (FEUP). Through this work, it was possible to strengthen and reaffirm that 3D printing with earth-based mortar has significant potential in the construction industry and that the incorporation of dispersed kraft paper fibres from the recycling of cement bags is an excellent resource to achieve good constructability in 3D printing with earth-based mortar.
24
Jones, Rhys, Ramesh Chandwani, Chris Timbrell, Anthony J. Kinloch e Daren Peng. "Thoughts on the Importance of Similitude and Multi-Axial Loads When Assessing the Durability and Damage Tolerance of Adhesively-Bonded Doublers and Repairs". Aerospace 10, n. 11 (7 novembre 2023): 946. http://dx.doi.org/10.3390/aerospace10110946.
Abstract (sommario):
Adhesively bonded doublers and adhesively bonded repairs are extensively used to extend the operational life of metallic aircraft structures. Consequently, this paper focuses on the tools needed to address sustainment issues associated with both adhesively bonded doublers and adhesively bonded repairs to (metallic) aircraft structures, in a fashion that is consistent with the building-block approach mandated in the United States Air Force (USAF) airworthiness certification standard MIL-STD-1530D and also in the United States (US) Joint Services Structural Guidelines JSSG-2006. In this context, it is shown that the effect of biaxial loads on cohesive crack growth in a bonded doubler under both constant amplitude fatigue loads and operational flight loads can be significant. It is also suggested that as a result, for uniaxial tests to replicate the cohesive crack growth seen in adhesively bonded doublers and adhesively bonded repairs under operational flight loads, the magnitude of the applied load spectrum may need to be continuously modified so as to ensure that the crack tip similitude parameter in the laboratory tests reflects that seen in the full-scale aircraft.
25
Laeli Fadloli, Hadi Susilo Arifin e Wonny Ahmad Ridwan. "Study on green concrete (porous concrete) sustainability in order to support the sustainable construction in Indonesia". Jurnal Pengelolaan Sumberdaya Alam dan Lingkungan (Journal of Natural Resources and Environmental Management) 13, n. 3 (20 settembre 2023): 432–43. http://dx.doi.org/10.29244/jpsl.13.3.432-443.
Abstract (sommario):
Currently implementation progress of green concrete (porous concrete0 is still very slow. The sustainable construction launched by the government has also not received a positive response from the construction sector. Greenery Open Spaces (RTH) and urban spatial planning in Indonesia have not accommodated the type of water-friendly pavement (porous concrete). Buildings that must meet the 30% of Green Base Cooeficient (KDH) also have not included the criteria for water-friendly concrete pavements. From the results of the Multi-Dimensional Scaling (MDS) analysis using Rapfish-R, it is known that the sustainability status of porous concrete is at a score of 71.9 (sufficiently sustainable). There is no leveraging factors from the ecological dimension. Leverage from economic dimensions, i.e.: added value for customer, durability and installation costs. Institutional dimensions, i.e.: application of ecolabels, product standards and criteria for RTH and KDH. Socio-technical dimension, i.e.: public understanding and perception, certification scheme, role of media, design and maintenance. From this leveraging factors, then can be formulized the strategy and roadmap for supporting the sustainable construction related to green concrete application
26
Chiu, W. K., R. Jones e M. Chao. "A Visco-Plastic Analysis of Bonded Joints under Complex Loading". Engineering Plastics 6, n. 1 (gennaio 1998): 147823919800600. http://dx.doi.org/10.1177/147823919800600103.
Abstract (sommario):
Adhesively bonded joints are traditionally designed using a single stress/strain curve to describe the mechanical behaviour of the adhesive. This paper addresses the validity of this assumption, given that the properties of film adhesives commonly used in bonded joints (e.g. FM 73) have been shown to demonstrate significant time dependencies both at room and high temperatures. To this end, a series of finite element analysis were conducted where the time dependent properties of the adhesive were modelled using a unified plasticity theory. The findings of this work show that, when performing certification assessments which require statements on the integrity and the durability of adhesively bonded joints subjected to complex load spectra, it may be necessary to consider an analysis which accounts for both time and load history effects. It is also shown that, for monotonic loading under constant loading rates, the peak stress strain response of the adhesive in a double lap joint follows the Glinka hypothesis for the notch stress-strain response of metals. However, it is shown that this approximation may not be valid for complex loading spectra.
27
Chiu, W. K., R. Jones e M. Chao. "A Visco-Plastic Analysis of Bonded Joints under Complex Loading". Polymers and Polymer Composites 6, n. 1 (gennaio 1998): 15–24. http://dx.doi.org/10.1177/096739119800600103.
Abstract (sommario):
Adhesively bonded joints are traditionally designed using a single stress/strain curve to describe the mechanical behaviour of the adhesive. This paper addresses the validity of this assumption, given that the properties of film adhesives commonly used in bonded joints (e.g. FM 73) have been shown to demonstrate significant time dependencies both at room and high temperatures. To this end, a series of finite element analysis were conducted where the time dependent properties of the adhesive were modelled using a unified plasticity theory. The findings of this work show that, when performing certification assessments which require statements on the integrity and the durability of adhesively bonded joints subjected to complex load spectra, it may be necessary to consider an analysis which accounts for both time and load history effects. It is also shown that, for monotonic loading under constant loading rates, the peak stress strain response of the adhesive in a double lap joint follows the Glinka hypothesis for the notch stress-strain response of metals. However, it is shown that this approximation may not be valid for complex loading spectra.
28
Pellizzon, Nayara Donelli, Alan Ricardo da Silva e Gustavo Garcia Otto. "Method for Setting Weight Tolerance Limits in High-Speed Weigh-in-Motion Systems: A Case Study in Brazil". Sustainability 14, n. 12 (8 giugno 2022): 7039. http://dx.doi.org/10.3390/su14127039.
Abstract (sommario):
High-speed weighing systems are considered a potential tool to restrain overloaded vehicles traffic, since this practice promotes threats to the infrastructure’s durability and to citizens’ safety. In view of the discussion on the certification of such systems, a method to define the weight tolerance limits of heavy goods vehicles was proposed in this work, using statistical experimentation methods. The method was applied to a case study in Brazil, which considered a high-speed weighing system and three known vehicles (3C, 2S3, and 3S3). The vehicles were loaded with gravel and the bending plate scale was used to set the weight. The test was conducted by checking the weight of the vehicles in the HS-WIM system and composed by the observance of three mandatory speeds (60, 70, and 80 km/h), in three different lateral positions in relation to the lane (center, left, and right), and at various times during the collection days. As result, maximum weights accuracy limits were obtained for gross vehicle weight (GVW) and for axes groups (G1, G2, and G3) as 13% (GVW), 20% (G1), 20% (G2), and 17% (G3).
29
Priddy, Lucy P., e Timothy W. Rushing. "Development of Laboratory Testing Protocol for Rapid-Setting Cementitious Material for Airfield Pavement Repairs". Transportation Research Record: Journal of the Transportation Research Board 2290, n. 1 (gennaio 2012): 89–98. http://dx.doi.org/10.3141/2290-12.
Abstract (sommario):
Many commercial off-the-shelf products for repairing portland cement concrete (PCC) pavements provide short set times, high early strengths, and the durability to withstand aircraft traffic. Twenty-five rapid-setting cementitious materials were investigated through laboratory and field evaluations to determine their suitability for repairing critical PCC airfield pavements. Standard laboratory tests were performed to characterize the properties of the materials and provide a protocol for assessing their suitability for field repairs. Criteria for using rapid-setting cementitious materials for repairing airfield pavements were published in 2008 by the U.S. Air Force. The criteria, based on laboratory and full-scale testing, allowed users to reduce the risk of premature failure of repairs by omitting unacceptable materials from their list of potential repair materials. The American Society of Testing and Materials published a similar test protocol in 2009. On the basis of a comparison of these two certification procedures and knowledge gained through field experience, the Air Force selection protocol was further updated in 2010 to improve the material selection process. The laboratory test methods used to develop the selection protocol along with the results from the material investigations are discussed in this paper.
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GÖK, Abdülkerim. "Investigation of the Turkey’s Climate for Service Lifetime of Photovoltaic Modules: A Mapping Approach". Gazi University Journal of Science Part A: Engineering and Innovation 10, n. 4 (31 dicembre 2023): 524–41. http://dx.doi.org/10.54287/gujsa.1357247.
Abstract (sommario):
The longevity of photovoltaic systems during real-world operation is a concern that needs to be addressed. Polymeric materials used in module constructions, particularly encapsulants, are susceptible to hydrolysis, which can lead to cell metallization corrosion and result in power loss and shortened service lifetime. One of the test protocols within the current certification standard of IEC 61215 is damp heat exposure, which subjects the modules to constant temperature and humidity level for a specific duration (85°C/85%RH for 1000 hours). However, its effectiveness as a reliability test for long-term durability is often debated. This study applies a methodology for calculating the equivalent damp heat testing time that corresponds to a targeted service lifetime (i.e., 30 years) in real-world conditions. The results are presented in the form of a country map, focusing on Turkey, illustrating the variations in testing times across different regions due to local climate conditions. This study shows that applying a single set of conditions for a fixed duration, as applied in the damp heat testing, to all modules with different components and for all climate conditions poses substantial risks when it comes to predicting service lifetime.
31
Broomfield, R. W., D. A. Ford, J. K. Bhangu, M. C. Thomas, D. J. Frasier, P. S. Burkholder, K. Harris, G. L. Erickson e J. B. Wahl. "Development and Turbine Engine Performance of Three Advanced Rhenium Containing Superalloys for Single Crystal and Directionally Solidified Blades and Vanes". Journal of Engineering for Gas Turbines and Power 120, n. 3 (1 luglio 1998): 595–608. http://dx.doi.org/10.1115/1.2818188.
Abstract (sommario):
Turbine inlet temperatures over the next few years will approach 1650°C (3000°F) at maximum power for the latest large commercial turbofan engines, resulting in high fuel efficiency and thrust levels approaching 445 KN (100,000 lbs.). High reliability and durability must be intrinsically designed into these turbine engines to meet operating economic targets and ETOPS certification requirements. This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, design technology for stresses and airflow, single crystal and directionally solidified casting process improvements, and the development and use of rhenium (Re) containing high γ′ volume fraction nickel-base superalloys with advanced coatings, including full-airfoil ceramic thermal barrier coatings. Re additions to cast airfoil superalloys not only improves creep and thermo-mechanical fatigue strength, but also environmental properties including coating performance. Re dramatically slows down diffusion in these alloys at high operating temperatures. A team approach has been used to develop a family of two nickel-base single crystal alloys (CMSX-4® containing 3 percent Re and CMSX®-10 containing 6 percent Re) and a directionally solidified, columnar grain nickel-base alloy (CM 186 LC® containing 3 percent Re) for a variety of turbine engine applications. A range of critical properties of these alloys is reviewed in relation to turbine component engineering performance through engine certification testing and service experience. Industrial turbines are now commencing to use this aero developed turbine technology in both small and large frame units in addition to aero-derivative industrial engines. These applications are demanding, with high reliability required for turbine airfoils out to 25,000 hours, with perhaps greater than 50 percent of the time spent at maximum power. Combined cycle efficiencies of large frame industrial engines are scheduled to reach 60 percent in the U. S. ATS programme. Application experience to a total 1.3 million engine hours and 28,000 hours individual blade set service for CMSX-4 first stage turbine blades is reviewed for a small frame industrial engine.
32
Winfield, Emily C., Robin J. Rader, Alexander M. Zhivov, Anders Dyrelund, Craig Fredeen, Oddgeir Gudmundsson e Brent Goering. "HVAC Best Practices in Arctic Climates". E3S Web of Conferences 246 (2021): 08004. http://dx.doi.org/10.1051/e3sconf/202124608004.
Abstract (sommario):
Arctic climates provide unique challenges for designers of HVAC, plumbing, and thermal energy systems. The importance of considering the operation outside air temperatures, system reliability, and building resiliency cannot be understated. The paper describes best practice examples of robust and reliable systems with the emphasis on their redundancy, durability, and functionality. The paper also discusses the most common heating and ventilation system approaches used in arctic climate with the emphasis on the importance of a maintenance program that allows building operators to successfully troubleshoot and maintain buildings in the arctic. More detailed discussion of concepts presented in this paper can be found in the Guide [1] where these concepts are illustrated by best practice examples from U.S. military bases in Alaska and Søndre Strømfjord, the international airport of Greenland that previously was used as a U.S. military base. The paper results from experts’ discussions during the Consultation Forum “Thermal Energy Systems Resilience in Cold/Arctic Climates” [2] and research conducted under the IEA EBC Annex 73, the Environmental Security Technology Certification Program (ESTCP) Project “Technologies Integration to Achieve Resilient, Low-Energy Military Installations” and U.S. Army Program project 633734T1500 under Military Engineering Technology Demonstration. The paper is complementary to the ASHRAE Cold Climate Design Guide [3] with a focus on resilience of thermal energy systems.
33
Banerjee, Sanjoy. "(Invited, Digital Presentation) Zinc-Based Energy Storage System Deployments and Developments for Transition to a Clean Energy Future". ECS Meeting Abstracts MA2022-01, n. 3 (7 luglio 2022): 455. http://dx.doi.org/10.1149/ma2022-013455mtgabs.
Abstract (sommario):
Rechargeable zinc-based alkaline batteries are an attractive electrochemical energy storage option with zinc anode costs of $3/kWh at full (theoretical) 2 electron capacity. When paired with high-capacity, inexpensive cathodes like manganese dioxide, and accounting for incomplete utilization of the active materials capacities, inactive materials costs (like for current collectors etc.) and manufacturing costs, rechargeable zinc-manganese dioxide batteries costing about $20-30/kWh appear to be within reach. The challenges to meeting these cost targets, and the current status of such rechargeable zinc alkaline batteries will be discussed. The first generation of rechargeable zinc-manganese dioxide batteries are now being deployed in residential, commercial, and utility-scale energy storage applications. In some cases, the applications require several thousand cells to meet the power and capacity requirements. Even such large systems do not require battery management systems at the cell level, being remarkably resilient to overcharging, without flammability and thermal runaway issues, and passing UL 9540A certification requirements without any protective measures being necessary. However, operation of these early deployments, indicate that to optimize systems performance and durability, energy management systems to manage overall systems charge-discharge protocols, taking the specific cell electrochemical characteristics, are desirable. The lessons learned and desirable innovations in designing and managing such large assemblies of cells will also be discussed.
34
Grygorcewicz, Paweł. "Results from Laboratory Tests of New Electric Brake Prototype". Journal of KONES 26, n. 3 (1 settembre 2019): 47–52. http://dx.doi.org/10.2478/kones-2019-0056.
Abstract (sommario):
Abstract The main idea of this article was to compare the results of new design electric brake to the older version of hydraulic brake in laboratory tests. The energy of braking should be very similar due to the same mass of the airplane. That is why the laboratory tests of both brakes were took place in the same stand. Of course, the parameters were similar but not at all. The main idea was to create the solution, which could be used in vehicle like airplane. The electric brakes could replace traditional hydraulic brake solution. The results could be interesting for every researcher who is interested in brakes. Other important idea of this article was to describe the tests of new electric brake prototype. The purpose of the tests was to check designing of electric brakes. The electric brake prototype should ensure sufficient efficiency, safety, reliability and durability during braking, which is required in certification processes and is particularly important when researching innovative solutions. It was really important to verify the design and check the parameters. Of course, there is really important to remember that in every new type of the prototype solutions there are many pros and cons, which are typical only for considered design. Nowadays every electric brake design is different because there is a lot of new concept.
35
Molent, Lorrie. "Managing Fatigue from Corrosion Pits in Aircraft Structures". Advanced Materials Research 891-892 (marzo 2014): 261–66. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.261.
Abstract (sommario):
Despite corrosion prevention or protection schemes/treatments and corrosion prevention and control plans, in-service corrosion does occur and has the potential to impact the structural integrity of aircraft. Whilst the fatigue management of the aircraft is generally well understood as reflected in typical Aircraft Structural Integrity Management Plans (ASIMP), which in some cases contain environmental degradation plans, limited provision beyond find and fix exists for corrosion repair. Thus the repair of corrosion can be a major through life cost driver as well as an aircraft availability degrader. This find and fix policy exists largely because tools are currently considered too immature to accurately assess the structural significance of corrosion when it is detected. In this paper a process is described which should allow an alternative to the current find (corrosion) and fix philosophy for pitting corrosion. The method is intended to maintain a probability of failure consistent with ASIMP structural certification requirements for fatigue cracks initiating from corrosion pits for a specific period. Unanticipated maintenance costs significantly more than planned maintenance. Thus delaying the repair of pitting corrosion until the next scheduled maintenance, should save considerable resources and improve aircraft availability. The development of analytical tools capable of accurately assessing the effect of corrosion on the durability of a structure would be considered a major advance for the ASIMP.
36
Bedon, Chiara, Filipe A. Santos e Marco Fasan. "Mechanical Analysis of the Quasi-Static and Dynamic Composite Action in PV Modules with Viscoelastic Encapsulant". Materials 17, n. 6 (13 marzo 2024): 1317. http://dx.doi.org/10.3390/ma17061317.
Abstract (sommario):
The mechanical analysis of photovoltaics and building integrated photovoltaics is a key step for their optimal design and certification, and requires careful consideration, alongside solar power, durability and functionality issues. The solar cells are encapsulated in thin interlayers that are usually composed of a viscoelastic Ethylene–Vinyl Acetate compound, and protected by thin glass and/or plastic layers. This paper investigates the out-of-plane bending response of a full-scale commercial PV module and focuses attention on the shear bonding efficiency of the thin encapsulant for quasi-static and dynamic mechanical considerations. The parametric analytical analysis, carried out in this study for a laminated glass plate, highlights the possible consequences of the viscoelastic shear coupling on the cross-section load-bearing demand in the covers. As a direct effect of severe operational conditions (i.e., ageing, non-uniform/cyclic thermal gradients, humidity, extreme mechanical/thermal loads, etc.) the shear rigidity and adhesion of these films can suffer from repeated/progressive modification and even degradation, and thus induce major stress and deflection effects in the out-of-plane mechanical response of the PV module components. The minimum shear bond efficiency required to prevent mechanical issues is calculated for various configurations of technical interest. Accordingly, it is shown how the quasi-static and dynamic mechanical performance of the system modifies as a function of a more rigid or weak shear coupling.
37
M. Shaju, Pragash. "Bio-based lightweight building blocks: A review". i-manager's Journal on Structural Engineering 11, n. 4 (2023): 40. http://dx.doi.org/10.26634/jste.11.4.19806.
Abstract (sommario):
This paper explores the development and utilization of bio-based lightweight building blocks as a sustainable solution in the construction industry. With increasing concerns about the environmental impact of traditional building materials, there is a growing need for eco-friendly alternatives. This study investigates the potential of natural and renewable materials, such as agricultural waste fibers, bamboo, or hemp, in combination with binders to create lightweight building blocks that offer both structural integrity and environmental sustainability. The research focuses on the formulation of these blocks, considering the optimal combination of bio-based materials and binders to achieve the desired properties. The performance characteristics of the bio-based lightweight building blocks, including structural strength, thermal insulation, fire resistance, and durability, are evaluated. The study also highlights the contribution of these blocks to sustainable construction practices, such as reducing carbon footprints and promoting resource efficiency. By providing an overview of the existing research in this field, the paper discusses the benefits and challenges associated with bio-based lightweight building blocks exploring economic feasibility, availability of materials, and compatibility with existing construction practices. Furthermore, the paper suggests avenues for future research, emphasizing the need for standardized testing protocols, certification systems, and a wider implementation of bio-based lightweight building blocks in the construction industry. This study sheds light on the potential of bio-based lightweight building blocks to mitigate environmental impact, improve sustainability, and drive innovation in construction practices.
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Barreto, M. F. F. Menna, A. P. Maran, D. C. C. Dal Molin e J. R. Masuero. "Performance evaluation of plastic spacers: proposal and development of evaluation methods". Revista IBRACON de Estruturas e Materiais 9, n. 6 (dicembre 2016): 911–52. http://dx.doi.org/10.1590/s1983-41952016000600006.
Abstract (sommario):
ABSTRACT The durability of reinforced concrete structures is highly dependent on the characteristics of the concrete cover to reinforcement and its thickness. The failure to obtain cover thickness is the factor with the largest influence on the premature corrosion of the reinforcement, which in turn is the main deterioration form of reinforced concrete structures. Studies indicate that the designed cover is not reached in the current constructions that adopt this structural solution, configuring a chronic, and not a sporadic problem. One of the observed causes for the failure in obtaining the minimum standardized cover is the incorrect use of spacers and the use of inadequate spacers. This is made more serious by the absence of a Brazilian standard to regulate the product and its use and, consequently, the absence of a quality certification from the responsible regulating agency. Focusing on spacers, requirements and performance criteria were proposed, in addition to methods for their assessment, with most being taken and adapted from international standards. Subsequently, some spacers available on the market were effectively tested according to the proposed methodology. No spacer model proved to be satisfactory according to the established performance approach. However, for each criteria and assessment methods proposed, there was, at least, one spacer model at the market which satisfied them, so it can be said that the criteria and methods are suitable for spacers performance evaluation. Faced with the performance diversity of the spacer models on offer, the need for a regulatory Brazilian standard for this product was confirmed in order to delimit the quality of spacers available on the market and to eliminate this variable as one of the causes for not obtaining the correct covering.
39
Ranger, Bryan J., Elizabeth Bradburn, Qingchao Chen, Micah Kim, J. Alison Noble e Aris T. Papageorghiou. "Portable ultrasound devices for obstetric care in resource-constrained environments: mapping the landscape". Gates Open Research 7 (6 dicembre 2023): 133. http://dx.doi.org/10.12688/gatesopenres.15088.1.
Abstract (sommario):
Background The WHO’s recommendations on antenatal care underscore the need for ultrasound assessment during pregnancy. Given that maternal and perinatal mortality remains unacceptably high in low- and middle-income countries (LMICs), these guidelines are imperative for achieving better outcomes. In recent years, portable ultrasound devices have become increasingly popular in LMICs due to their cost-effectiveness, useability, and adoptability in resource-constrained settings. This desk review presents the capabilities and costs of currently available portable ultrasound devices, and is meant to serve as a resource for clinicians and researchers in the imaging community. Methods A list of ideal technical features for portable ultrasound devices was developed in consultation with subject matter experts (SMEs). Features included image acquisition modes, cost, portability, compatibility, connectivity, data storage and security, and regulatory certification status. Information on each of the devices was collected from publicly available information, input from SMEs and/or discussions with company representatives. Results 14 devices were identified and included in this review. The output is meant to provide objective information on ideal technical features for available ultrasound systems to researchers and clinicians working in obstetric ultrasound in LMICs. No product endorsements are provided. Conclusions This desk review provides an overview of the landscape of low-cost portable ultrasound probes for use in obstetrics in LMICs, and provides a description of key capabilities and costs for each. Methods could be applied to mapping the landscape of portable ultrasound devices for other clinical applications, or may be extended to reviewing other types of healthcare technologies. Further studies are recommended to evaluate portable ultrasound devices for usability and durability in global field settings.
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Yasev, A. H. "Experimental modeling mechanical qualities of heatcover screens". System technologies 4, n. 141 (28 marzo 2022): 169–79. http://dx.doi.org/10.34185/1562-9945-4-141-2022-14.
Abstract (sommario):
Basic physical and mechanical properties of heatcover composition material that is used for making of protective screens are experimentally investigated. For this purpose on the example of flowed plastic STEF executed (with the use of traditional charts) research at small (less than 1 m/s) and high (more than 3 m/s) rate-of-change of ladening. At small speeds of ladening durability of material was investigated at superficial deformation, tension, bend and change. At high speeds work of destruction and shock viscidity was determined. Organization and realization of experiments were done according to rules of planning experiments. All investigations were made with the using kinds of experimental equipment which had according certifications of control their quality and accuracy. Obtained results were treated by methods of mathematical statistics and researches of their dispersions. The results of experimental researches drawn on at the decision of concrete design-engineering tasks, in particular, at development of equipment and choice of the modes of crushing of composition materials during their utilization (although, undoubtedly, the obtained data have more wide value). For example, data of intruding conical elements in material were used for selecting optimal angles for working elements of equipment. Correlations between power parameters of intruding process were used for selecting power parameters of equipment for crushing of composition materials. Equipment and technology for crushing of composition materials during their utilization, which are designed on the base of these investigations, have new useful technical and technological specialties, that is why, authors obtained document of intellectual property on this object.
41
Kim, Jae-Hyang, e Seung-Hoon Han. "Indoor Daylight Performances of Optimized Transmittances with Electrochromic-Applied Kinetic Louvers". Buildings 12, n. 3 (24 febbraio 2022): 263. http://dx.doi.org/10.3390/buildings12030263.
Abstract (sommario):
Windows with low visible light transmittance (VLT) and g-values are preferred to reduce the building’s energy consumption. However, low VLT and g-value can create an unpleasant indoor daylight environment. A glass with freely adjustable VLT and g-value as required has been developed and is called smart glass. In this study, the recently developed VLT adjustable smart glass is targeted. Some studies were conducted on the VLT adjustment status of smart windows to create an appropriate indoor lighting environment. Although research on smart glass has been conducted through ecofriendly building certification systems such as LEED in the US, BREEAM in the UK, CASBEE in Japan, and GSEED in South Korea, it was pointed out that there is a limit to creating a uniformity. Therefore, the previous study analyzed the VLT conditions to create a minimal indoor daylight environment. The purpose of this study is to propose and analyze a louver-type electrochromic façade that can create a uniform indoor illuminance. A simulation method was used, and a range of changes in indoor illuminance that could be controlled through an electrochromic louver was derived. The simulation was performed using the Rhino 6′s Grasshopper program based on the Radiance engine. Electrochromic is a class of smart glass with high VLT variable range and durability. The conditions for deriving the optimal daylight environment according to the composition, VLT, and angle of the electrochromic louver were analyzed. The evaluation was made against the criteria of LEED v4.1. Data on the composition, VLT, and angle adjustment of the electrochromic louver that can obtain a high LEED v4.1 daylight score were derived, and organized in tables. Considering the composition and angle, it was found that the daylight environment of the electrochromic louver adjusted with a VLT of 25% to 45% was excellent in composition.
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Silva, C., T. Sousa, J. Bessa, F. Cunha, M. Costa, A. Roças e R. Fangueiro. "BEHAVIOUR ASSESSMENT OF TRIDIMENSIONAL MULTILAYER FIBROUS STRUCTURES AS RESPIRATORY PROTECTION SUBSTRATES". TEXTEH Proceedings 2021 (22 ottobre 2021): 50–57. http://dx.doi.org/10.35530/tt.2021.39.
Abstract (sommario):
Despite the growing appearance of new solutions for social masks, there are still few aimed for the use by professionals in frequent contact with the public, since depending on the of the functions they perform, still have special needs regarding thermophysiological comfort, high protection level and reusability, such as firefighters and police officers. Aiming at the development of a multilayer filtration system combining threedimensional and planar fibrous structures, the present study intends to verify the feasibility of applying warpknit spacers as diffuser filters for nano and micro particles. Therefore, three different spacer structures performance was studied, and then combined with planar knit structures to enhance the comfort characteristics and its bacterial filtration efficiency (BFE). The diffusion filtration performance of the samples, due to the particle size, it was found a direct relation between the outer layer density and porosity with its filtration capacity of microparticles. Moreover, the increase in the spacer thickness revealed more problems diffusing water vapor molecules. To achieve the standard requirements, the samples Techno_1 and 2 were developed and tested. The addition of a new fibrous structure increased substantially the filtration efficiency without damaging the comfort characteristics of the Spacers. Considering the BFE standard tests for facemask certification, despite it was possible to achieve filtration rates above 70% for the samples Techno_1 and 2. In addition, its washability and performance durability were tested and stated as viable to be applied as a social facemask with level III of protection for at least 25 washing cycles, despite having noticed a decrease in the filtration efficiency, in both samples, in the order of 10%, due to the unbalance of mechanical properties of the fibrous structures in the multilayer systems.
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Maury-Ramírez, Aníbal, e Nele De Belie. "Environmental and Economic Assessment of Eco-Concrete for Residential Buildings: A Case Study of Santiago de Cali (Colombia)". Sustainability 15, n. 15 (6 agosto 2023): 12032. http://dx.doi.org/10.3390/su151512032.
Abstract (sommario):
Although the circular economy principles date back to the late 1960s, only with the recent stimulus from the European Commission and the Ellen McArthur Foundation has this concept gained attention worldwide. The City Hall of Santiago de Cali (Colombia) is implementing a circular economy model through a sustainable construction handbook and its certification. Among others, these stimulate the use of eco-concrete using fly ash and blast furnace slag coming from local industries (industrial symbiosis). Although concretes with these supplementary cementitious materials have been widely investigated regarding mechanical and durability properties, the economic and environmental impacts have been scarcely and independently evaluated, making the material selection a complex process. Therefore, this article presents the environmental and economic assessment of eco-concretes using fly ash and blast furnace slag for the design of a house located in Santiago de Cali (Colombia). The environmental and economic impacts are estimated by means of the environmental life cycle assessment (LCA) and life cycle costing (LCC), which are methodologies based on the ISO and ASTM standards implemented in the online software Building for Environmental and Economic Sustainability (BEES), which was selected for this case study. The results indicate that 40% fly ash concrete or 50% blast furnace slag would be recommended for reducing acidification or global warming potential, respectively. However, considering the existing public policies, the best option for the case study is 50% slag concrete. These results are of significant importance as they allow providing data-based recommendations for designers during the selection of the different eco-concretes. Additionally, these results might help establish a national roadmap to reduce carbon dioxide emissions from the construction sector, which are projected to continue increasing until 2050.
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Yeremenko, V. S., e M. B. Osintseva. "Utilization of machine and their elements is actual science and practical task". System technologies 4, n. 141 (28 marzo 2022): 3–13. http://dx.doi.org/10.34185/1562-9945-4-141-2022-01.
Abstract (sommario):
Basic physical and mechanical properties of heatcover composition material that is used for making of protective screens are experimentally investigated. For this pur-pose on the example of flowed plastic STEF executed (with the use of traditional charts) research at small (less than 1 m/s) and high (more than 3 m/s) rate-of-change of lad-ening. At small speeds of ladening durability of material was investigated at superficial deformation, tension, bend and change. At high speeds work of destruction and shock viscidity was determined. Organization and realization of experiments were done ac-cording to rules of planning experiments. All investigations were made with the using kinds of experimental equipment which had according certifications of control their quality and accuracy. Obtained results were treated by methods of mathematical statis-tics and researches of their dispersions. The results of experimental researches drawn on at the decision of concrete de-sign-engineering tasks, in particular, at development of equipment and choice of the modes of crushing of composition materials during their utilization (although, undoubt-edly, the obtained data have more wide value). For example, data of intruding conical elements in material were used for selecting optimal angles for working elements of equipment. Correlations between power parameters of intruding process were used for selecting power parameters of equipment for crushing of composition materials. Equipment and technology for crushing of composition materials during their uti-lization, which are designed on the base of these investigations, have new useful tech-nical and technological specialties, that is why, authors obtained document of intellec-tual property on this object.
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de las Heras, Ricardo Ballestar, Sergio Fernández Ayala, Estefanía Molina Salazar, Fernando Carrillo, Javier Cañavate e Xavier Colom. "Circular Economy Insights on the Suitability of New Tri-Layer Compostable Packaging Films after Degradation in Storage Conditions". Polymers 15, n. 20 (19 ottobre 2023): 4154. http://dx.doi.org/10.3390/polym15204154.
Abstract (sommario):
The environmental degradation of the films used in packaging is a key factor in their commercial use. Industrial and academic research is aimed at obtaining materials that have degradation features that ensure their eco-sustainability but, at the same time, preserve their use properties during storage and distribution periods. This study analyzes the degradability behavior over time of commercial packaging that meets the requirements of the UNE 13432 standard and the prEN 17427 (2020) home composting certification requirements under standard storage conditions. The study attempts to provide insight into the durability of the films under standard storage conditions, verifying that this type of packaging has a useful life of more than 12 months and that after this storage period it still retains the usability properties for which it was conceived. The analyzed sample has been manufactured using a three-layer technology under some commercial formulations based on PBAT + STARCH + PLA and has been analyzed monthly for 12 consecutive months. The macroscopic monitoring of the degradation of the sample has been carried out through the evolution of the mechanical properties and the quantification of the color changes (very important in films) via colorimetry. The nature of the observed variations has been justified at the microstructural level from the data obtained in calorimetric analysis (DSC) and from the characterization using FTIR. The results indicate a loss of properties in the tensile, elongation and impact tests and a behavior of stability or improvement in the tear properties of the film. Analyzing the microstructural changes, it is observed that the degradation of a hydrolytic and thermo-oxidative type occurs in the amorphous part of the film. The conclusion of this study is that the proposed packaging, focused on domestic composting and stored under standard conditions, has a useful life of more than 12 months. This period should be sufficient to cover the stages of production, storage and final use.
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Kumar, Ravinder, Priyanka Kaundal, Rahul Kumar Tiwari, Milan Kumar Lal, Hema Kumari, Rakesh Kumar, Kailash Chandra Naga et al. "Development of Reverse Transcription Recombinase Polymerase Amplification (RT-RPA): A Methodology for Quick Diagnosis of Potato Leafroll Viral Disease in Potato". International Journal of Molecular Sciences 24, n. 3 (28 gennaio 2023): 2511. http://dx.doi.org/10.3390/ijms24032511.
Abstract (sommario):
Potatoes are developed vegetatively from tubers, and therefore potato virus transmission is always a possibility. The potato leafroll virus (PLRV) is a highly devastating virus of the genus Polerovirus and family Luteoviridae and is regarded as the second-most destructive virus after Potato virus Y. Multiple species of aphids are responsible for the persistent and non-propagating transmission of PLRV. Due to intrinsic tuber damage (net necrosis), the yield and quality are drastically diminished. PLRV is mostly found in phloem cells and in extremely low amounts. Therefore, we have attempted to detect PLRV in both potato tuber and leaves using a highly sensitive, reliable and cheap method of one-step reverse transcription-recombinase polymerase amplification (RT-RPA). In this study, an isothermal amplification and detection approach was used for efficient results. Out of the three tested primer sets, one efficiently amplified a 153-bp product based on the coat protein gene. In the present study, there was no cross-reactivity with other potato viruses and the optimal amplification reaction time was thirty minutes. The products of RT-RPA were amplified at a temperature between 38 and 42 °C using a simple heating block/water bath. The present developed protocol of one-step RT-RPA was reported to be highly sensitive for both leaves and tuber tissues equally in comparison to the conventional reverse transcription-polymerase chain reaction (RT-PCR) method. By using template RNA extracted employing a cellular disc paper-based extraction procedure, the method was not only simplified but it detected the virus as effectively as purified total RNA. The simplified one-step RT-RPA test was proven to be successful by detecting PLRV in 129 samples of various potato cultivars (each consisting of leaves and tubers). According to our knowledge, this is the first report of a one-step RT-RPA performed using simple RNA extracted from cellular disc paper that is equally sensitive and specific for detecting PLRV in potatoes. In terms of versatility, durability and the freedom of a highly purified RNA template, the one-step RT-RPA assay exceeds the RT-PCR assay, making it an effective alternative for the certification of planting materials, breeding for virus resistance and disease monitoring.
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Oliynyk, Olena, e Mariia Tokar. "Principles of sustainable development in family leisure centers". Current problems of architecture and urban planning, n. 65 (17 marzo 2023): 236–50. http://dx.doi.org/10.32347/2077-3455.2023.65.236-250.
Abstract (sommario):
The article examines the principles of sustainable development, which dictate new approaches and tools for the design of modern multifunctional family leisure centers in the conditions of a metropolis. The study is aimed at determining the approaches and principles that must be used in the modern architecture of family leisure centers in order to meet global demand and the requirements of sustainable development, which are guided by the UN and other world public organizations. The use of ecological and energy-saving means in the process of designing multifunctional family leisure centers, aimed at achieving the durability of buildings, reducing operating costs, reducing the cost of construction, influencing the awareness of the population about reducing the level of pollution, is based on ecological principles and careful management of natural resources and autonomy.
The new challenges of time and the high rhythm of life in cities require in the future an increase in the quality and number of recreation places, facilities for recovery and spending time together, namely multifunctional family leisure centers. Meanwhile, high standards and requirements for the design and architecture of new buildings, dictated by the principles of sustainable development, require new design, engineering, innovative solutions and approaches. The world began to change more rapidly in the last 30 years, and its population must quickly adapt to new conditions. At the same time, there are some things that do not change or change very little: the insolation of the sun, the speed of the wind, the physical characteristics of concrete and metal, and others.
Thus, architects can create buildings and projects using modern technologies, principles and tools of sustainable development, and as a result, these projects can be durable and can be called sustainable. There are many systems for assessing the sustainability of buildings around the world. In addition to the US Green Building Council, which administers the Leadership in Energy and Environmental Efficiency (LEED) system, there are other rating systems that have been developed to measure the level of sustainability of buildings and provide best practice experiences with the highest level of certification.
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Bürger, Stefan, Carsten Cremers e Niels Urban. "Design and Construction of a LT-PEM Fuel Cell System for Aviation Application". ECS Meeting Abstracts MA2023-02, n. 38 (22 dicembre 2023): 1857. http://dx.doi.org/10.1149/ma2023-02381857mtgabs.
Abstract (sommario):
Fuel cell technology has gained considerable attention as an alternative power source for mobility applications. Fuel cell systems are already integrated in ground applications like trucks, cars, and busses. One reason is, that they have the potential to provide an environmentally friendly power supply solution compared to traditional combustion engines. Moreover, fuel cell drive trains offer several potential benefits, such as improved energy efficiency, noise reduction and no local emissions and even zero CO2 emission if they are fueled with green hydrogen. On the other hand, there are several key challenges associated with the integration of fuel cell technology into mobility applications, such as safety, durability, weight, and cost. These challenges become even more difficult when flight applications are considered, due to the higher . We present our research of a fuel cell system design, which is constructed to power a one seat airplane, the Antares E2. This system will utilize compressed Hydrogen as fuel to power up to six electronic motors via an electric bus. The airplane needs 90 kW of power mainly for its electric propulsion and can be operated up to a ceiling altitude of 6500 m (21,300 ft). For redundancy and safety, it is necessary to split the power output to at least two systems. Therefore, each system must have a power output of 45 kW. The fuel cell system's design takes various factors into account, such as lightweight and compact components as well as safety analysis to ensure the operation in flight. To reach aviation standards a full FMEA analysis is conducted, to calculate the risks of operating the systems on an airplane. The goal is to have a fuel cell system which is eligible for operating an aircraft. We want to present first results of our research, consisting of first design to ground operation and include some simulations for flight conditions. A successful development and certification of this fuel cell system would represent a significant milestone in the pursuit of sustainable aviation technologies, since it would be one of the first system which features approved airworthiness. This technology has the potential to reduce emissions and noise pollution associated with traditional combustion engines. Further research and development efforts are required to optimize the performance and reduce the cost of this fuel cell system. This work is funded by the Federal Ministry for Digital and Transport (BMDV) in the project “H2GA” under the grant 03B10707. The authors declare that the opinions expressed in this submission are their own and are based on a thorough review of existing scientific literature.
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Nuraini, Ani, Nurminingsih Nurminingsih e Yeny Sulistyowati. "Pendampingan Rebranding Kemasan Produk Sayuran Segar (Keran Payung Bambu) Kelompok Wanita di RPTRA Payung Tunas Teratai dan Bambu Petung". Jurnal Pelayanan dan Pengabdian Masyarakat (Pamas) 7, n. 4 (31 ottobre 2023): 388–98. http://dx.doi.org/10.52643/pamas.v7i4.3530.
Abstract (sommario):
According to a survey conducted by the Bank of Indonesia (BI) in July 2021, the Economic Conditions Index (IKE) was recorded at 67.1. IKE is composed of three components, namely the Current Income Index, Job Availability Index, and Durable Goods Purchase Index. On the other hand, the rapid expansion of internet access in Indonesia has been influencing consumer shopping trends, especially among those aged 25-38. Through various e-commerce platforms, consumers can access a wide range of products relevant to their daily lives, such as fresh fruits and vegetables. Therefore, it is essential to empower the community through robust and healthy entrepreneurial activities to support the local economy. This can be achieved through various means, including mentorship and training. The role of the community in the RPTRA Payung Tunas Teratai and Bambu Petung areas, through independent business activities, cannot rely on external entities. Hence, the development of micro and small-scale businesses accessible to the community is necessary. The community is encouraged to utilize available land for agriculture, including in RPTRA Payung Tunas Teratai and Bambu Petung. The types of vegetables produced are diverse, including water spinach, long beans, mustard greens, pumpkin, and more. The goal of these activities is to enhance marketing and income through rebranding. Special thanks to the Directorate General of Higher Education, Research, and Technology, Ministry of Education, Culture, Research, and Technology, for providing research funding in 2023, RPTRA Payung Tunas Teratai and RPTRA Bambu Petung, as well as the involvement of the Manpower, Transmigration, and Energy Office, Sub-district Office of Tourism and Creative Economy in East Jakarta, Satpel PPUKM, Satpel KPKP, and Satpel Dinsos in the Cipayung District, who participated and coordinated in the series of research activities. The activities took place on Friday, September 8, 2023, in RPTRA Payung Tunas Teratai in the Cipayung Sub-district and on Wednesday, September 12, 2023, in RPTRA Bambu Petung in the Bambu Apus Sub-district. A total of 79 participants attended, divided into two groups in RPTRA Payung Tunas Teratai and Bambu Petung. The results of this research were increased income, skills, and empowerment of partners. The research outputs include a national accredited journal publication (published in PAMAS, Sinta 4), electronic media coverage (Radar), video documentation (Website and YouTube URINDO), and additional intellectual property (Flyer) with certification. The impact of these activities on the achievement of higher education Key Performance Indicators (IKU) includes students gaining experience outside the campus (IKU-2), faculty members engaging in off-campus activities (IKU-3), and Faculty Work Results Used by the Community (IKU-5). Through these research activities, the beneficiary community members received information on how to process and package vegetables to prolong their shelf life and increase their market value. This series of research activities has proven to be highly beneficial, reducing losses for business operators through appropriate product packaging methods to maintain product freshness, durability, and appeal.
Keywords: Rebranding, Fresh Vegetables, Women's Groups
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Ford, D. A., K. P. L. Fullagar, H. K. Bhangu, M. C. Thomas, P. S. Burkholder, P. S. Korinko, K. Harris e J. B. Wahl. "Improved Performance Rhenium Containing Single Crystal Alloy Turbine Blades Utilizing PPM Levels of the Highly Reactive Elements Lanthanum and Yttrium". Journal of Engineering for Gas Turbines and Power 121, n. 1 (1 gennaio 1999): 138–43. http://dx.doi.org/10.1115/1.2816301.
Abstract (sommario):
Turbine inlet temperatures have now approached 1650°C (3000°F) at maximum power for the latest large commercial turbofan engines, resulting in high fuel efficiency and thrust levels approaching or exceeding 445 kN (100,000 lbs.). High reliability and durability must be intrinsically designed into these turbine engines to meet operating economic targets and ETOPS certification requirements. This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, computerized design technology for stresses and airflow, and the development and application of rhenium (Re) containing, high γ’ volume fraction nickel-base single crystal superalloys, with advanced coatings, including prime-reliant ceramic thermal barrier coatings (TBCs). Re additions to cast airfoil superalloys not only improve creep and thermomechanical fatigue strength but also environmental properties, including coating performance. Re slows down diffusion in these alloys at high operating temperatures [1]. At high gas temperatures, several issues are critical to turbine engine performance retention, blade life, and integrity. These are tip oxidation in particular for shroudless blades, internal oxidation for lightly cooled turbine blades, and TBC adherence to both the airfoil and tip seal liner. It is now known that sulfur (S) at levels, <10 ppm but >0.2 ppm in these alloys reduces the adherence of α alumina protective scales on these materials or their coatings by weakening the Van der Waal’s bond between the scale and the alloy substrate. A team approach has been used to develop an improvement to CMSX-41 alloy which contains 3 percent Re, by reducing S and phosphorus (P) levels in the alloy to <2 ppm, combined with residual additions of lanthanum (La) + yttrium (Y) in the range 10-30 ppm. Results from cyclic, burner rig dynamic oxidation testing at 1093°C (2000°F) show thirteen times the number of cycles to initial alumina scale spallation for CMSX-4 [La + Y] compared to standard CMSX-4. A key factor for application acceptance is of course manufacturing cost. The development of improved low reactivity prime coats for the blade shell molds along with a viable, tight dimensional control yttrium oxide core body are discussed. The target is to attain grain yields of single crystal CMSX-4 (ULS) (La + Y) turbine blades and casting cleanliness approaching standard CMSX-4. The low residual levels of La + Y along with a sophisticated homogenisation/solutioning heat treatment procedure result in full solutioning with essentially no residual γ/γ’ eutectic phase, Ni (La, Y) low melting point eutectics, and associated incipient melting pores. Thus, full CMSX-4 mechanical properties are attained. The La assists with ppm chemistry control of the Y throughout the single crystal turbine blade castings through the formation of a continuous lanthanum oxide film between the molten and solidifying alloy and the ceramic core and prime coat of the shell mold. Y and La tie up the <2 ppm but >0.2 ppm residual S in the alloy as very stable Y and La sulfides and oxysulfides, thus preventing diffusion of the S atoms to the alumina scale layer under high temperature, cyclic oxidising conditions. La also forms a stable phosphide. CMSX-4 (ULS) (La + Y) HP shroudless turbine blades will commence engine testing in May 1998.