bluuebunny/crossref_metadata_2025 huggingface dataset:
Multicompetencia lingüística y cambio de código en el humor infantil
Authors: Pastor Cesteros Susana
Published: January 2021

Abstracta

Los fenómenos de multilingüismo y multicompetencia lingüística han sido abordados desde muy diferentes
perspectivas (Martin-Jones, Blackledge y Creese 2012; Cook y Wei 2016). El objetivo de este artículo, sin embargo, es ponerlos en relación con los procesos de
cambio de código y con la percepción de la diversidad lingüística para estudiar su presencia y efecto en un corpus de 184
narraciones escritas humorísticas de niños de 8 a 12 años, obtenido en el marco del proyecto I+D La formación de la
conciencia figurativa en la etapa de formación primaria: el humor y la fraseología (FFI2016-76047-P). El análisis
cuantitativo y cualitativo del corpus ha permitido ver en las conclusiones hasta qué punto el conocimiento implícito y explícito
de varias lenguas a esas edades incide en el cambio de código y en las referencias a otras lenguas y si ello aparece o no de un
modo intencionado para provocar un efecto cómico (Timofeeva-Timofeev 2017).
Vortex generation from a fiber laser by a polarization rotation technique
Authors: Wang Sha , Zhang Zhicheng , Wu Yajie , Hu Xingwen , Yang Huomu , Zhou Shouhuan
Published: January 2021

Vortex beams have wide applications in optical tweezers, optical communications and so on. Long period fiber gratings, mode selective couplers, few mode fiber Bragg gratings or specially designed fibers are often used to generate vortex beams from fiber lasers. New methods of mode selection in fiber lasers are always attractive. When transverse modes propagate along a multimode fiber, the polarization state of each mode rotates differently due to birefringence. In this paper, a linear cavity fiber laser and a ring cavity fiber laser using a polarization rotation technique are proposed to select the output laser mode. Three waveplates and a polarizing beam splitter (PBS) are used as a mode loss controller inside the laser cavity. By rotating the waveplates inside the cavity, different laser modes can be selected and achieved from the laser cavity by the PBS. Experimentally, the fundamental LP01 mode, the LP11 mode, the LP21 mode and vortex beams with ±1 topological charges were achieved.
Chemical and phase composition of the novel superelastic Ti-Zr-Nb alloy with a high Zr content
Authors: Barilyuk D V , Bazlov A I , Prokoshkin S D , Konopatsky A S
Published: January 2021

The novel superelastic Ti-44Zr-10Nb (at.%) alloy was obtained by the vacuum arc remelting method and subjected to homogenization (950 °C, 60 min) and thermomechanical treatment (TMT), which consisted of cold rolling (CR) with a 25% thickness reduction rate and consequent post-deformation annealing (PDA) at 550 °C for 30 min. The analysis of the chemical composition was conducted by the EDS method. It was demonstrated that the obtained chemical composition of the alloy was in good correspondence with the nominal chemical composition. The phase composition of the alloy after TMT was investigated by the XRD technique. The lattice parameters of β and α” phases were measured using XRD data to calculate the crystallographic recovery strain limit. The maximum transformation strain of 7.3% was obtained in the [011]β direction.
Quantitative analysis of {100}Al plate/lath- and <100>Al rod-shaped precipitates in an aged Al-Cu-Mg-Si alloy using TEM
Authors: Gazizov M R , Holmestad R , Marioara C D , Kaibyshev R O
Published: January 2021

Precipitate parameters, such as length, diameter and thickness of rationally oriented {100}Al plate/lath-shaped and <100>Al rod-shaped precipitates in an age-hardenable Al-Cu-Mg-Si alloy have been examined quantitatively. An appropriate procedure of the plate- and rod-shaped precipitate separation was suggested to determine the precipitate parameters as well as their distribution histograms using bright-(BF) and dark-field (DF) transmission electron microscopy (TEM) images taken in the <100>Al and <110>Al zone axes (ZA).
Correlation of the tribological properties of LIPSS on TiN surface with 3D parameters of roughness
Authors: Gazizova M Yu , Smirnov N A , Kudryashov S I , Chen J , Ahmadeev Yu H , Goncharov I Yu , Shugurov V V , Prokopenko N A
Published: January 2021

The relationships between friction coefficients and 3D spatial roughness parameters, such as Sci (surface core fluid retention index), Svi (surface valley fluid retention index) and Sbi (surface bearing index), have been investigated for the laser-induced periodic surface structures (LIPSS) on the TiN coatings. Two types of the surface structures (cross-like and parallel ones) with different roughness levels were obtained using a fs-laser. It has been shown that the proposed roughness parameters correlate with the friction coefficients measured for the LIPSSs.
Grain structure evolution during friction-stir welding of 6061-T6 aluminum alloy
Authors: Kalinenko A , Vysotskiy I , Malopheyev S , Mironov S , Kaibyshev R
Published: January 2021

In this work, electron backscattered diffraction (EBSD) was used to examine the evolution of the grain structure during friction stir welding of aluminum alloy 6061-T6. In the entire FSW range studied, the microstructure evolution was found to be governed by continuous recrystallization. An increase in the welding temperature resulted only in microstructural coarsening.
Microstructural aspects of friction stir welding
Authors: Mironov S
Published: January 2021

Microstructural aspects of friction-stir welding were briefly reviewed. Particular emphasis was given to material flow, crystallographic texture, grain structure development, precipitation phenomena, phase transformations, and thermal stability
Mechanical behavior of titanium alloy Ti-6Al-4V with vacuum-plasma protective coating V+(Ti-V)N at elevated temperatures
Authors: Modina Iu M , Valiev R R , Dyblenko Yu M , Smyslova M K , Semenova I P
Published: January 2021

This work is devoted to improving the performance properties of the titanium alloy Ti-6Al-4V due to hardening by forming an ultrafine-grained structure (UFG) using severe plastic deformation (SPD) by equal channel angular pressing (ECAP) and then applying a protective coating V+(Ti-V)N on its surface by vacuum-plasma deposition. The effect of the coating on the increase in the strength characteristics of the UFG material is demonstrated in comparison with the CG and UFG state without coating.
Effect of deformation techniques on the microstructure and mechanical properties of a copper alloy
Authors: Morozova A , Pilipenko A , Tkachev M , Lugovskaya A , Belyakov A , Kaibyshev R
Published: January 2021

The microstructure and mechanical properties of a Cu-0.25%Mg alloy subjected to either equal channel angular pressing (ECAP) or combined cold working, including ECAP followed by rolling and then drawing at room temperature, were investigated. ECAP led to the formation of strain-induced boundaries and the development of ultrafine equiaxed grains with an average size of about 0.6 μm after 4 passes. The microstructure after the combined cold working included fibrous grains elongated in the rolling/drawing direction with a sharp texture containing <001> and <111> fibers. The transversal grain size after combined cold working to a total strain of 5.7 achieved 0.43 μm. The yield strength and ultimate tensile strength after ECAP to a total strain of 9.6 were 570 and 600 MPa; whereas those after combined cold working to a total strain of 8.7 were 745 and 780 MPa, respectively. The reason of the difference in mechanical properties was discussed.
Precipitation-hardened refractoryTi-Nb-Hf-Al-Ta high-entropy alloys
Authors: Panina E , Yurchenko N , Zherebtsov S , Salishchev G , Stepanov N
Published: January 2021

This study reports the structure and mechanical properties of new refractory Ti37.5Nb12.5Hf25Al25, Ti40Nb30Hf15Al15, and Ti40Nb20Ta10Hf15Al15 (at.%) high entropy alloys. After annealing at 1200 °C for 24 h, the program alloys had a single-phase B2 structure. Further annealing at 600 °C for 24 h resulted in the formation of Widmanstatten orthorhombic particles (O-phase) in the bcc matrix. The Ti40Nb30Hf15Al15 and Ti40Nb20Ta10Hf15Al15 alloys annealed at T = 1200 °C showed moderate strength and good ductility (>50%) at 22 and 600 °C; while the Ti37.5Nb12.5Hf25Al25 alloy was stronger, but less ductile at both temperatures. Subsequent annealing at T = 600 °C significantly increased the strength of the Ti40Nb30Hf15Al15 alloy at 22 and 600 °C, maintaining compressive sufficient ductility at room-temperature.
Effect of carbon content on cryogenic mechanical properties of CoCrFeMnNi high entropy alloy
Authors: Semenyuk A , Klimova M , Shaysultanov D , Chernichenko R , Zherebtsov S , Stepanov N
Published: January 2021

The effect of the carbon content (0-2 at.%) on the structure and mechanical properties at room and cryogenic temperatures of CoCrFeNiMn-based high entropy alloys with reduced Cr concentration was studied. The as-cast alloys were cold rolled to a thickness reduction of 80% and annealed at 800°C for 1 hour. As a result, a fully recrystallized microstructure with a grain size of 6.4 μm was produced in the carbon-free alloy. The recrystallized grain size was much smaller (1.5 μm in the alloy with 2.0 at.% of C) due to the pinning effect of the precipitated M23C6 carbides. The yield strength of the alloys increased with an increase in the carbon concentration from 313 MPa to 636 MPa, while the elongation to fracture slightly decreased from 56% to 43%, respectively, in the alloys with 0 and 2 at.% of C. A decrease in the test temperature to 77K resulted in a significant increase in both the strength and ductility of the alloys. The alloys had high values of impact toughness of 140 J/cm2 and 85 J/cm2, respectively, in the alloys with 0 and 2 at.% of C. A decrease in the testing temperature did not have a noticeable effect on the impact toughness.
Synthesis and electric transportation properties of high-entropy oxides based on cerium oxide
Authors: Yapryntsev M N , Sudzhanskaya I V , Lyubushkin R A , Yapryntseva E N
Published: January 2021

CeGdRLaPrO2-δ (where R: La, Y and Dy) rare-earth high-entropy oxides (HEOx) with the Ia-3 (206) structure were obtained. The structural, microstructural and transport properties of the compounds were studied. All samples exhibiting good homogeneity and electrical conductivity typical of materials for the manufacture of solid electrolytes.
Understanding the Role of Graphene on the Moisture Absorption in Graphene/Polymer Nanocomposites
Authors: Almudaihesh F , Alfaris H , Sangha P , Pullin R , Eaton M
Published: January 2021

This study focuses on understanding the effect of graphene, when introduced in epoxy systems, on the overall moisture absorption capacity and behaviour of epoxy resin composites subjected to hydrothermal conditions. Pristine epoxy resin and epoxy resin incorporating functionalised and unfunctionalised graphene reinforcement were manufactured and exposed to 90°C purified water for 30 days. The flexural and tensile properties were observed for both unaged and aged specimens. A lower moisture absorption capacity was observed for graphene enhanced specimens as opposed to pristine epoxy resin, which suggests the potential of graphene as a barrier to moisture ingress. Despite the lower mass gain observed, the performance of the nano-filled resins exhibits a larger reduction in properties following water absorption.
New Aircraft Anti/de-Icing Technologies
Authors: Vertuccio Luigi , Foglia Fabiana , Pantani Roberto , Guadagno Liberata
Published: January 2021

The ice formation on the leading edge of aircraft wings is a crucial problem for aircraft flight. In this work, an efficient method for the anti/de-icing function based on the development of electro-conductive film heaters is prosed. A green solvent casting process is employed in the experimental procedure adopted for the film preparation. Two kinds of expanded graphite have been used. The different morphological feature of the two expanded graphites affects the heating performance of the films heaters. The film prepared using the nanoparticles with a higher aspect ratio manifests better electrical and heating performance, and therefore the de-icing activation at a lower applied voltage.
Design of a morphing leading edge as a high lift device for a regional aircraft
Authors: Contell Asins C , Landersheim V , Wacker J-D , Adachi S , Arnold-Keifer S , May M
Published: January 2021

Morphing technologies can provide a significant contribution to reduction of noise and fuel consumption for future aircraft. In the framework of the European Aviation research programme Clean Sky 2, a design of a morphing leading edge was developed, which allows the simultaneous increase of wing chord and camber to adapt the airfoil to different airspeed conditions. The final design has a sliding contact at the bottom, whereas the upper surface is continuous with variable camber. In contrast to classical high lift devices, the lift coefficient can be increased without adding sources for turbulences at the upper wing surface. CFD analyses have been performed in order to quantify the aerodynamic performance of the designed morphing leading edge. Furthermore, a design concept both for the skin and for the actuation system is presented. The skin is designed using carbon fiber reinforced plastics (CFRP). In order to achieve both the required stiffness and flexibility, a customized non-constant layup is developed. Its feasibility for the high deformations during morphing is demonstrated by means of both numerical analysis and experimental validation. The electro-mechanical actuation system is designed to completely fit inside the morphing leading edge while still considering space for other subsystems. Besides the space requirements also weight, mountability and bird strike aspects are taken into account. Altogether, for the overall design of a morphing system is presented in this paper, various design challenges are highlighted and appropriate solutions for these challenges are discussed.
Cooling system design for the internal combustion engine of a BWB UAV prototype
Authors: Alexiou E , Dimitriou S , Dimopoulos T , Paliaikos D , Panagiotou P , Yakinthos K
Published: January 2021

The current study presents an analytical design methodology for a compact thermal management system (cooling system) of a high-power density internal combustion rotary engine. The engine is installed on a fixed wing, tactical Blended-Wing-Body (BWB) Unmanned Aerial Vehicle (UAV) prototype that has been developed for the aerial delivery of cargo and lifesaving supplies. The design methodology is based mainly on a low-fidelity thermodynamic model and on high-fidelity Computational Fluid Dynamics (CFD) analyses. The results are validated against wind tunnel experiments for the cooling system of the engine. The overall methodology is divided into two distinct segments, the design of the heat exchanger (HEX) and the sizing of the cold-air inlet ducts. The low-fidelity thermodynamic model is based on 0D and 1D textbook methods and well-established formulae from the existing literature. The thermodynamic model is used for the calculation of the geometrical characteristics of the HEX. The high-fidelity CFD modeling is employed to yield a more detailed investigation of the flow field around the HEX and provide information about whether the airflow velocity requirements, for the 0D and 1D model, are met. Additionally, the detailed CFD computations assist the design of high-efficiency inlet ducts, in order to secure optimal airflow through the HEX and around the engine compartment. Using the proposed methodology, a functional HEX experimental prototype is designed and manufactured, as a proof of concept, in order to be thoroughly examined on a test rig in laboratory conditions. Multiple experiments are conducted in a variety of inlet temperatures and airflow velocities, for the validation and fine-tuning of the overall proposed design methodology. The study concludes with the final HEX design, as well as an analysis of its integration aspects on the tactical BWB UAV prototype.
Aerodynamic and stability analysis of a VTOL flying wing UAV
Authors: Bliamis C , Zacharakis I , Kaparos P , Yakinthos K
Published: January 2021

The stability analysis of an aerial vehicle is an of great importance integral part of its design procedure. It is of even greater importance in the case of tailless aircraft, which are prone to stability issues. In the present study, the aerodynamic and stability characteristics of a Vertical Take-off and Landing (VTOL) fixed wing Unmanned Aerial Vehicle (UAV), designated as MPU RX-4, are investigated. The MPU RX-4 has a flying wing layout and is capable of performing, both conventional flight, like a regular fixed wing aerial vehicle, as well as vertical hovering, like a multicopter, adapting on different operational demands and achieving rapid field deployment. In this study, the preliminary design phase of the MPU RX-4 is presented and the aerial vehicle’s aerodynamic performance, as well as, its stability and control behavior are assessed using both semi-empirical correlations, specifically modified for lightweight flying wing UAVs, and Computational Fluid Dynamics (CFD) analyses. These correlations are employed to estimate the non-dimensional aerodynamic coefficients for various flight conditions (e.g. cruise, loiter, maximum speed, etc.) of the MPU RX-4 flight envelope. Furthermore, the correlations are validated with dedicated CFD analyses in order to assure their level of accuracy. Finally, the MPU RX-4 stability and control derivatives, and the required control surfaces deflection for steady level flight are computed, in order to assess its overall aerodynamic performance and flight characteristics.
Multidisciplinary design of the wing for aircraft preliminary design purposes
Authors: Hospodár Pavel , Drábek Armand
Published: January 2021

In this paper, an aerodynamic and wing structure is investigated by low-fidelity methods. Bell-shaped lift distribution was rediscovered in the last decade as a perspective alternative to traditional wing design. This leads to lower aerodynamic drag than elliptical lift distribution for a given lift force and root bending moment. Root bending moment is used as a surrogate model of wing structure weight. It is relatively raw simplification introduced by Prandtl to estimate the weight of the spar as a main part of the wing structure. For a more accurate wing weight estimation, the main parts of the wing are dimensioned under CS-23 regulation in this work. The design procedure starts with defining the elementary parameters of the wing shape (chord/twist distribution, wingspan). After geometry generating a non-linear lifting line is used to calculate aerodynamic characteristics for all regime, determined from the flight envelope. The dimensions of a spar, ribs and skin are calculated in the next step of the procedure for given bending moment, load and torque moment distribution. The structure of the wing is assumed as a two-spar, manufactured by aluminum. A target of design is to find out the shape of the wing for given weight. The solution is verified by CFD calculation.
Analysis of fuselage skin reinforcements with beam element models in flexible aircraft panels for ditching simulations
Authors: Muñoz C Leon , Kohlgrüber D , Langrand B
Published: January 2021

This paper is dedicated to the use of beam element models for skin structural reinforcements in guided ditching simulations with a flexible aircraft panel. This approach was analysed by means of finite element simulations of the structure subjected to a constant pressure load and guided ditching loading conditions. To verify this approach, finite element models of different discretization types and different mesh sizes were considered in the computations. Moreover, guided ditching simulations were enhanced by comparisons with the coupled Finite Element-Smoothed Particle Hydrodynamics and the Arbitrary Lagrangian Eulerian methods.
Advanced materials and technologies for compressor blades of small turbofan engines
Authors: Pavlenko Dmytro , Dvirnyk Yaroslav , Przysowa Radoslaw
Published: January 2021

BACKGROUND: Manufacturing costs, along with operational performance, are among the major factors determining the selection of the propulsion system for unmanned aerial vehicles (UAVs), especially for aerial targets. OBJECTIVES: In this paper, the design requirements and operating parameters of small turbofan engines for single-use and reusable UAVs are analysed to introduce alternative materials and technologies for manufacturing their compressor blades, such as sintered titanium, a new generation of aluminium and an alloy based on titanium aluminides. METHODS: To assess the influence of severe plastic deformation (SPD) on the hardening efficiency of the proposed materials, the alloys in the coarse-grained and submicrocrystalline states were studied. Changes in physical and mechanical properties of materials were taken into account. The thermodynamic analysis of the compressor was performed in a finite element analysis system (ANSYS) to determine the impact of gas pressure and temperature on the aerodynamic surfaces of compressor blades of all stages. RESULTS: Based on thermal and structural analysis, the stress and temperature maps on compressor blades and vanes were obtained, taking into account the physical and mechanical properties of advanced materials and technologies of their processing. The safety factors of the components were established based on the assessment of their stress-strength reliability. Thanks to nomograms, the possibility of using the new materials and the technologies was confirmed in view of the permissible operating temperature and safety factors of aerofoils. CONCLUSIONS: The proposed alternative materials and production technologies for the compressor blades and vanes meet the design requirements of the turbofan at lower manufacturing costs.
The ACONIT project: an innovative design approach of active flow control for surge prevention in gas turbines
Authors: Dazin A , Joseph P , Romano F , Gallas Q , Marty J , Aigouy G , Stôβel M , Niehuis R
Published: January 2021

The objective of the ACONIT project is to design, manufacture and test actuators for flow control for an implantation in an aircraft engine. The actuators will fulfil aeronautics requirement in order to increase the Technology Readiness Level (TRL) in this domain. In particular, for the present proposal, one plans to focus on the extension of the stable operating range of axial compressor, allowing thus a reduction of the surge margin through postponing the stall onset. To do so, the first objective of the work is to improve the knowledge of the flow physics of an efficient flow control system by joint numerical and experimental analyses performed in a low speed, single stage axial compressor. The results of this analysis will be used to derive the fluidic specifications for high-TRL actuators and control systems. These specifications will be the base for the design and manufacturing of amplified piezo-electric actuator prototypes whose fluidic performance and operational performance in an environment with vibration and controlled level of temperature will be precisely evaluated before manufacturing final actuators that will be integrated in a full-scale engine test facility. Their performance will be evaluated in terms of Surge Margin Improvement (SMI) as well as in terms of energy balance between the induced consumption and the machine performance improvements. The consortium grouped for carrying out this project is composed of a SME (CTEC), two academic institutions (Bundeswehr University Munich and ENSAM) and a Research Centre (ONERA). It groups skills ranging from internal flow analysis in turbomachinery, to flow control or actuators design, manufacturing and characterisations.
Thermal Management challenges for HEA – FUTPRINT 50
Authors: Affonso Walter , Gandolfi Ricardo , dos Reis Ricardo Jose Nunes , da Silva Carlos Roberto Ilário , Rodio Nicolas , Kipouros Timoleon , Laskaridis Panagiotis , Chekin Andrei , Ravikovich Yury , Ivanov Nikolay , Ponyaev Leonid , Holobtsev Dmitry
Published: January 2021

Electric and Hybrid-Electric Aircraft (HEA) incorporate new systems, which demand an integration level higher than classical propulsion architectures systems do. High power electrical motors, converters, batteries or fuel cells, and distributed propulsion, all introduce new kinds of heat sources and dynamics that have to be accounted for and regulated. The latent opportunity to explore synergies among these systems requires the development of new models and their coupling with multi-disciplinary design optimization (MDO) toolchains. Also, an understanding of the implications into aircraft operations and trade-offs are critical to evaluate and validate gains at the aircraft level. This paper provides a definition of thermal management and functions of thermal management system (TMS) in aircraft, HEA thermal management challenges, main opportunities, conclusions and the way forward. A discussion of road ahead, regarding development of capabilities to support the design of TMS will be brought to the fore along the project, showcasing the open approach of FUTPRINT50 to be driven by open collaboration in order to accelerate the entry into service of this type of aircraft.
Safety and Certifiability Evaluation of Distributed Electric Propulsion Airplane in EASA CS-23 Category
Authors: Jézégou Joël , Sufyan Umair
Published: January 2021

Distributed Electric Propulsion (DEP) is one of the unconventional airplane architectures of interest in the quest for decreasing aviation environmental footprint. This configuration integrates strong and innovative couplings between systems and aircraft design disciplines. To address limitations of the traditional approach for certification and of the associated means of compliance when certifying innovative products, the European Union Aviation Safety Agency (EASA) issues in 2017 a novel certification philosophy that relies on high-level objective-based safety requirements. In this context, this paper presents a safety and certifiability evaluation of DEP airplane in EASA CS-23 category, with a methodology for aircraft-level safety assessment during preliminary design, a certification gap analysis with regards to existing means of compliance, and some proposals to clear the certification path for DEP configuration.
Economically driven requirements for a hybrid-electric 19-passenger commuter aircraft
Authors: Schuh G , Spangenberg M , Zhang Q
Published: January 2021

The appeal of reduced travel and transport times and electrification of aircraft drive the development of new aircraft for short distances. The goal of the CleanSky2 project ELICA (ELectric Innovative Commuter Aircraft) is to provide a preliminary design of a hybrid-electric 19-passenger commuter aircraft, whereby the passenger limit is defined by certification. This paper describes the initial set of Top Level Aircraft Requirements (TLARs) based on both a benchmark with existing 19-passenger commuter aircraft and the analysis of requirements derived from potential future markets Regional Air Mobility (RAM) and thin-haul air cargo services. Both of these are introduced briefly. A literature-based framework for TLARs and an analysis of existing airfield infrastructure in Europe and the US together with population data in the direct surroundings of such airfields are investigated. Additionally, insights on cabin design are discussed and important features such as noise emissions and operational cost of such aircraft are highlighted.
Validation of the simulation tool for environmentally friendly aircraft cargo fire protection system
Authors: Pathak A. , Norrefeldt V.
Published: January 2021

One of the objectives of CleanSky-2 project is to develop an Environmentally Friendly Fire Protection (EFFP) system (halon free fire suppression system) for the aircraft cargo hold. For this, an Aircraft Demonstrator including the cargo hold has been equipped with a nitrogen suppression system. The demonstrator is located in the Flight Test Facility low pressure vessel and can thus be subjected to realistic cruise pressure conditions and take-off and descent pressure variations. As a design tool, a zonally refined simulation model to predict the local oxygen and nitrogen concentration distribution in the cargo hold has been developed using the Indoor Environment Simulation Suite (IESS). The model allows for fast transient simulations of the suppression system operation. This paper presents a model validation case of a knockdown during cruise, followed by a holding phase and descent (repressurization of the cargo hold).
Effect of increased cabin recirculation airflow fraction on relative humidity, CO2 and TVOC
Authors: Norrefeldt Victor , Mayer Florian , Herbig Britta , StrÖhlein Ria , Ivandic Ivana , Wargocki Pawel , Lei Fang
Published: January 2021

In the CleanSky 2 ComAir study, subject tests were conducted in the Fraunhofer Flight Test Facility cabin mock-up. This mock-up consists of the front section of a former in-service A310 hosting up to 80 passengers. In 12 sessions the outdoor/recirculation airflow ratio was altered from today’s typically applied fractions to up to 88% recirculation fraction. This leads to increased relative humidity, carbon dioxide (CO2) and Total Volatile Organic Compounds (TVOC) levels in the cabin air, as the emissions by passengers become less diluted by outdoor, dry air. This paper describes the measured increase of relative humidity, CO2 and TVOC level in the cabin air for the different test conditions.
Diagnostics of Electro-Mechanical Actuators Based Upon the Back-EMF Reconstruction
Authors: Quattrocchi G , Berri P C , Vedova Dalla M D L , Maggiore P
Published: January 2021

Electrical systems are gradually replacing the more traditional hydraulic and pneumatic solutions for the transmission of secondary energy for onboard aircraft equipment. Therefore fault detection and health management strategies properly conceived for electrical devices are becoming a highly relevant topic for research and development in the aerospace disciplines. One possible practical implementation of these methodologies would be the identification of parameters for diagnostic and prognostic monitoring, which are highly sensitive to incipient faults but, at the same time, are less influenced by operating conditions (external loads, command input, temperatures, etc.). In this paper, the authors evaluated the effectiveness of counter-electromotive force (back-EMF) coefficient as a prognostic parameter, emphasizing a novel sampling approach that significantly lower the computational effort required while maintaining a good back-EMF coefficient curve reconstruction. The approach is virtual sensor-like, using only already available data for the correct operation of the BLDC motor. The proposed method was tested by evaluating the back-EMF coefficient reconstruction as a function of some progressive failures typical of EMA motors, such as inter-turn partial shorts and rotor static eccentricity. Its robustness to external disturbances has been tested by evaluating different actuation commands and operating conditions. As expected, the back-EMF signal shows a marked dependence on the considered failure modes and, at the same time, a suitable insensitivity to the other external factors.
A Team Allocation Decision for Aircraft Fleet Maintenance
Authors: Pereira D P , Melicio R , Mendes V M F
Published: January 2021

This paper is about a computer application for planning maintenance of aircraft fleet in what regards allocation of skilled technicians. The formalization for this planning is a mathematical programming problem written as a minimizing one. The decision variables are the allocation of the skilled technicians. The data are the number of available technicians, the working hours needed to accomplish maintenance, the costs due to the daily operation of facilities, and due to the fleet downtime. Although, the formalization is of a non-linear integer-programming problem, a transformation of variables from positive integer ones to Boolean ones is conceivable and allows a reformulation as a pure integer linear programming problem. Also, a relaxation of the integer variables to continuous ones allows for a relaxed formulation as a convex non-linear programming problem. A case study of two fleets illustrates both formulations: solved by the pyomo library calling the GLPK for the pure linear integer programming problem and calling solvers in Scipy library for the relaxed formulation. An inference presented about the results of the case study addresses the issue of using nonlinear programming to emulate the solution of linear integer programming.
Development of an autonomous power supply for oil and gas fields based on a gas turbine unit driven by an active-reactive turbine
Authors: Bazykin D A , Barakov A V
Published: January 2021

The relevance of the task lies in the development of an autonomous source of electrical power for oil and gas fields, significantly remote from power lines and the necessary infrastructure. An autonomous source is made on the basis of a gas turbine unit driven by an active-reactive turbine, which fuel is associated petroleum, low-pressure, untreated natural gas without preliminary preparation. The developed installation does not require frequent maintenance, the consumption of lubricants, preliminary preparation of fuel gas, and has relatively small overall dimensions. Atmospheric air is used as a working fluid while working surfaces are not subject to pollution. The work provides information on mining equipment, which must be continuously supplied with electric energy, on the currently available analogs of the developed device and their shortcomings. A diagram of the proposed gas turbine installation is given, its structure and principle of operation are described. Information about the developed equipment is given. Preliminary calculations of the main parameters are made, the results are shown.
Investigation of gas-sensitive properties of cobalt oxide films
Authors: Bespoludin V V , Polyakov V V , Petrov V V , Nesterenko A V , Vakulov Z E
Published: January 2021

This paper presents a study of the gas-sensitive properties of cobalt oxide films formed by rapid thermal annealing on a sitall substrate. Cobalt films were formed on a pre-cleaned sitall substrate by vacuum thermal evaporation. The thickness of the deposited films was 470 nm. Rapid thermal annealing (RTA) was used to form cobalt oxide films. RTA of cobalt films was carried out at temperatures of 500°C, 600°C and 700°C. The resistivity of the films after RTA at 500°C, 600°C and 700°C was 3.6 × 10–2 Ohm·cm, 1.2 × 103 Ohm·cm and 5.8 × 103 Ohm·cm, respectively. The surface morphology of the obtained films was investigated by the AFM method. The gas sensitivity of cobalt oxide films was studied for gases like CO, NO2, CH4, C3H6O (vapors of acetone), C3H8O (vapors of isopropyl) and NH3·H2O (vapors of ammonium hydroxide 25%). The gas sensitivity was measured at 300°C. The results of gas sensitivity measurements showed significantly lower sensitivity to gases such as CO, NO2 and CH4. It was found that cobalt oxide films have good sensitivity to gases such as C3H6O, NH3·H2O and C3H8O. Sensitive elements based on cobalt oxide films are interesting as gas sensor elements for the detection of C3H6O, NH3·H2O and C3H8O.
Multi-unit modular wind farm for areas of low wind potential
Authors: Dorjiev S S , Bazarova E G , Rosenblum M I , Morenko K S
Published: January 2021

Many dispersed sites are remote from the power grid in agriculture. The centralized power supply of these objects with electric energy from the power grid is unprofitable. During the year, tests were conducted in full-scale conditions of wind power plants with different parameters under conditions of power shortage. The article proposes the development of a multi-unit wind power plant with an additive block, where the energy from multiple winds receiving devices is summed. The article shows that the wind turbine operates in a stable mode in an extended range of wind speeds of 4500 hours per year and generates rated power even in conditions of power shortage due to energy storage and operation of the wind turbines with different parameters. It is two times longer than the power of the wind turbine with separate generators during the year. Studies have shown that at low wind speeds of 4-5 m/s, a 1 kW wind power plant generates up to 840 W at wind speeds of 4-6 m/s, the efficiency of a multi-unit wind power plant is 4 times higher than the overall efficiency of individual wind power plants operating on their own generators.
Detection of damage sites on overhead power lines with a voltage of 110 kV or higher
Authors: Kuryanov V N , Kul’kov V G , Skopova E M , Firsov Yu V , Norov D S
Published: January 2021

The article is devoted to problems in the electric grid complex related to ageing of components of power lines, reduction of reliability and increase the number of failures. It shows the need of development of scientific and methodical bases of perfection of management and organization of the system of technical maintenance and repair of equipment in power network systems, taking into account the current state of development of the power industry. Problems of disconnections of high-voltage power lines occur periodically in many countries and the search for options for their early elimination or pre-termination is a very urgent task. Researching and developing methods and devices for early detection of fault locations will minimize the time for troubleshooting and thus reduce downtime and economic losses for all parties, both the grids organization and the electricity consumer. The paper presents the results of research and development of devices used to detect places of power line damage in the conditions of “digital transformation” of the energy complex. The implementation of the developed proposals will have a positive impact on reducing losses from under-supply of electricity and will reduce the time for identifying fault locations associated with determining the locations of short-circuit currents.
Modeling of the cooling process of long pipelines for transportation of liquid hydrogen
Authors: Kalyadin O V , Sergeev A V , Grebennikov A A , Lopatin A Yu
Published: January 2021

A simplified model of cooling long insulated pipelines with liquid hydrogen flowing through them has been developed. The model allows us to determine the flow parameters at different points in time and to estimate the pipeline cooling time. When developing the model, the following assumptions were made: the linear velocities of the liquid and vapor are equal, the phases are in a state of thermodynamic equilibrium, the dependencies obtained for a single-phase flow are applicable to determine the friction coefficient of a two-phase flow. Based on the model, an automated algorithm for calculating the cooling process of a long pipeline with cryogenic components was developed. It allows us to obtain data for plotting the temperature fields of the pipeline walls and the flow of the transported cryogenic liquid at different times, as well as to determine the cooling time of the pipeline and the moment of the onset of a stationary single-phase flow. The calculation results are in good agreement with the experimental data.
Digital twin for smart electricity distribution networks
Authors: Podvalny S L , Vasiljev E M
Published: January 2021

This paper presents the results of composing a digital model of critical states of the power distribution network with intelligent control. A specific example of a power network with thirty transformer substations connected by main and reserve cables is discussed. The analysis of critical events occurring in the power system was carried out, and a set of decision rules was formed to counter these events. A practical need was noted for regular updating and expansion of the list of critical events and corresponding parrying rules. It is shown that it is expedient to use faceted active neural networks with a structure similar to that of the controlled object as a digital twin model of intelligent control of the system under consideration. The use of such neural networks based on the rule “one event - one ensemble of neurons” provides the digital duplicate model with the ability to unlimited cumulative expansion, similar to the evolutionary property of natural biological systems.
Challenges and opportunities to develop enediyne natural products as payloads for antibody-drug conjugates
Authors: Adhikari Ajeeth , Shen Ben , Rader Christoph
Published: January 2021

Calicheamicin, the payload of the antibody-drug-conjugates (ADCs) gemtuzumab ozogamicin (Mylotarg®) and inotuzumab ozogamicin (Besponsa®), belongs to the class of enediyne natural products. Since the isolation and structural determination of the neocarzinostatin chromophore in 1985, the enediynes have attracted considerable attention for their value as DNA damaging agents in cancer chemotherapy. Due to their non-discriminatory cytotoxicity towards both cancer and healthy cells, the clinical utilization of enediyne natural products relies on conjugation to an appropriate delivery system, such as an antibody. Here, we review the current landscape of enediynes as payloads of first-generation and next-generation ADCs.
In Vitro Evaluation of Common Antimicrobial Solutions Used for Breast Implant Soaking and Breast Pocket Irrigation—Part 2: Efficacy Against Biofilm-Associated Bacteria
Authors: Jewell Mark L , Bionda Nina , Moran Alison V , Bevels Elizabeth J , Jewell Hillary L , Hariri Sara , Leung Braden K
Published: January 2021

Background

Biofilm-associated bacteria have been observed in both breast implant revision and tissue expander-implant exchange surgeries. The utilization of antimicrobial solutions in breast surgery, especially those containing triple antibiotics (TAB) and/or 10% povidone-iodine (PI), may help reduce existing biofilm-associated bacteria, which is particularly important in a mature breast pocket that may contain residual bacteria from a previously colonized implant surface or, theoretically, bacteria that may arrive postoperatively through hematogenous spread.

Objectives

A series of in vitro assessments was performed to evaluate the antimicrobial utility of TAB and PI, either alone or in combination, against preformed biofilm-associated bacteria.

Methods

Preformed biofilm-associated gram-positive and gram-negative bacterial strains were exposed to TAB and PI ± TAB for up to 30 minutes in a bacterial time-kill assay. Efficacy of various dilutions of PI and the effects of serum protein on PI efficacy were also investigated.

Results

TAB was ineffective at the timeframes tested when utilized alone; when utilized in conjunction with PI, significant log reduction of all biofilm-associated bacterial species tested was achieved when treated for at least 5 minutes. PI alone at a concentration of 25% or higher was also effective, although its efficacy was negatively affected by increasing serum protein concentration only for Staphylococcus epidermidis.

Conclusions

Our data indicate that PI-containing solutions significantly reduce biofilm-associated bacteria, suggesting potential utility for breast pocket irrigation during revision or exchange surgeries. Care should be taken to minimize excessive dilution of PI to maintain efficacy.
2021 ISHNE / HRS / EHRA / APHRS Collaborative Statement on mHealth in Arrhythmia Management: Digital Medical Tools for Heart Rhythm Professionals
Authors: Varma Niraj , Cygankiewicz Iwona , Turakhia Mintu , Heidbuchel Hein , Hu Yufeng , Chen Lin Yee , Couderc Jean-Philippe , Cronin Edmond M , Estep Jerry D , Grieten Lars , Lane Deirdre A , Mehra Reena , Page Alex , Passman Rod , Piccini Jonathan , Piotrowicz Ewa , Piotrowicz Ryszard , Platonov Pyotr G , Ribeiro Antonio Luiz , Rich Robert E , Russo Andrea M , Slotwiner David , Steinberg Jonathan S , Svennberg Emma
Published: January 2021

This collaborative statement from the International Society for Holter and Noninvasive Electrocardiology / Heart Rhythm Society / European Heart Rhythm Association / Asia Pacific Heart Rhythm Society describes the current status of mobile health (“mHealth”) technologies in arrhythmia management. The range of digital medical tools and heart rhythm disorders that they may be applied to and clinical decisions that may be enabled are discussed. The facilitation of comorbidity and lifestyle management (increasingly recognized to play a role in heart rhythm disorders) and patient self-management are novel aspects of mHealth. The promises of predictive analytics but also operational challenges in embedding mHealth into routine clinical care are explored.
Pre-operative heart failure worsens outcome after aortic valve replacement irrespective of left ventricular ejection fraction
Authors: Thilén Maria , James Stefan , Ståhle Elisabeth , Lindhagen Lars , Christersson Christina
Published: January 2021

Aims

Left ventricular ejection fraction (LVEF) affects the outcome of aortic valve replacement (AVR) in aortic stenosis (AS). The study aim was to investigate the prognostic importance of concomitant cardiovascular disease in relation to pre-operative LVEF.

Methods and results

All adult patients undergoing AVR due to AS 2008–14 in a national register for heart diseases were included. All-cause mortality and hospitalization for heart failure during follow-up after AVR, stratified by preserved or reduced LVEF (≤50%), were derived from national patient registers and analysed by Cox regression. During the study period, 10 406 patients, median age 73 years, a median follow-up of 35 months were identified. Preserved LVEF was present in 7512 (72.2%). Among them, 647 (8.6%) had a history of heart failure (HF) and 1099 (14.6%) atrial fibrillation (AF) before the intervention. Pre-operative HF was associated with higher mortality irrespective of preserved or reduced LVEF: hazard ratio (HR) 1.64 [95% confidence interval (CI) 1.35–1.99] and 1.58 (95% CI 1.30–1.92). Prior AF was associated with a higher risk of mortality in patients with preserved but not in those with reduced LVEF: HR 1.62 (95% CI 1.36–1.92) and 1.05 (95% CI 0.86–1.28). Irrespective of LVEF, pre-operative HF and AF were associated with an increased risk of post-operative heart failure hospitalization.

Conclusion

In patients planned for AVR, a history of HF or AF, irrespective of LVEF, worsens the post-operative prognosis. Heart failure and AF can be seen as markers of myocardial fibrosis not necessarily discovered by LVEF and the merely use of it, besides symptoms, for the timing of AVR seems suboptimal.