bluuebunny/crossref_metadata_2025_split huggingface dataset:
Remote radio control of insect flight reveals why beetles lift their legs in flight while other insects tightly fold
Authors: Kosaka Takumi , Gan Jia Hui , Long Le Duc , Umezu Shinjiro , Sato Hirotaka 
Published: January 2021

Abstract
In the research and development of micro air vehicles, understanding and imitating the flight mechanism of insects presents a viable way of progressing forward. While research is being conducted on the flight mechanism of insects such as flies and dragonflies, research on beetles that can carry larger loads is limited. Here, we clarified the beetle midlegs' role in the attenuation and cessation of the wingbeat. We anatomically confirmed the connection between the midlegs and the elytra. We also further clarified which pair of legs are involved in the wingbeat attenuation mechanism, and lastly demonstrated free-flight control via remote leg muscle stimulation. Observation of multiple landings using a high-speed camera revealed that the wingbeat stopped immediately after their midlegs were lowered. Moreover, the action of lowering the midleg attenuated and often stopped the wingbeat. A miniature remote stimulation device (backpack) mountable on beetles was designed and utilized for the free-flight demonstration. Beetles in free flight were remotely induced into lowering (swing down) each leg pair via electrical stimulation, and they were found to lose significant altitude only when the midlegs were stimulated. Thus, the results of this study revealed that swinging down of the midlegs played a significant role in beetle wingbeat cessation. In the future, our findings on the wingbeat attenuation and cessation mechanism are expected to be helpful in designing bioinspired micro air vehicles.
Understanding the combined impacts of weeds and climate change on crops
Authors: Vilà Montserrat , Beaury Evelyn M , Blumenthal Dana M , Bradley Bethany A , Early Regan , Laginhas Brittany B , Trillo Alejandro , Dukes Jeffrey S , Sorte Cascade J B , Ibáñez Inés 
Published: January 2021

Abstract
Crops worldwide are simultaneously affected by weeds, which reduce yield, and by climate change, which can negatively or positively affect both crop and weed species. While the individual effects of environmental change and of weeds on crop yield have been assessed, the combined effects have not been broadly characterized. To explore the simultaneous impacts of weeds with changes in climate-related environmental conditions on future food production, we conducted a meta-analysis of 171 observations measuring the individual and combined effects of weeds and elevated CO2, drought or warming on 23 crop species. The combined effect of weeds and environmental change tended to be additive. On average, weeds reduced crop yield by 28%, a value that was not significantly different from the simultaneous effect of weeds and environmental change (27%), due to increased variability when acting together. The negative effect of weeds on crop yield was mitigated by elevated CO2 and warming, but added to the negative effect of drought. The impact of weeds with environmental change was also dependent on the photosynthetic pathway of the weed/crop pair and on crop identity. Native and non-native weeds had similarly negative effects on yield, with or without environmental change. Weed impact with environmental change was also independent of whether the crop was infested with a single or multiple weed species. Since weed impacts remain negative under environmental change, our results highlight the need to evaluate the efficacy of different weed management practices under climate change. Understanding that the effects of environmental change and weeds are, on average, additive brings us closer to developing useful forecasts of future crop performance.
Long term impacts of transitions in charcoal production systems in tropical biomes
Authors: van ‘t Veen Hanneke , Eppinga Maarten Boudewijn , Mwampamba Tuyeni Heita , Ferreira Dos Santos Maria João 
Published: January 2021

Abstract
Mitigation of greenhouse gas emissions through transitions to biomass-based renewable energy may result in higher land needs, affecting ecosystem services and livelihoods. Charcoal is a biomass-based renewable energy that provides energy for hundreds of millions of households worldwide and generates income for 40 million people. However, it currently causes up to 7% of the global deforestation rate. In the absence of affordable alternative fuels, it is necessary to identify conditions that foster sustainable charcoal production. In this study, we (a) develop a stylized model that simulates feedbacks between forest biomass and charcoal production, and (b) use the model to examine the effects of interventions that foster sustainable charcoal systems through transitions to communal management or private systems, increases in carbonization efficiency and charcoal demand reductions. Our model simulations suggest that at low demand, a transition is unnecessary. At intermediate to high demands, interventions that increase carbonization efficiency and/or reduce demand should be combined with transitions to communal management (at intermediate forest biomass levels) or private systems (at low forest biomass levels) to ensure long-term sustainability of charcoal systems and avoid collapse within 100 years. These results highlight multiple pathways for sustainable charcoal production systems tailored to meet supply and demand. All pathways are feasible across tropical biomes and could foster the simultaneous continuation of forests and charcoal production in the near future.
Spark plasma sintering of Si3N4-YAG nanocomposite
Authors: Andreev P V , Rostokina E Ye , Alekseeva L S , Murashov A A , Boldin M S , Balabanov S S 
Published: January 2021

Abstract
Spark plasma sintering (SPS) of mixtures based on silicon nitride nanopowders (Si3N4) was considered. A method for creating a mixture based on nanosized Si3N4 and a sintering additive of yttrium-aluminum garnet (YAG, Al5Y3O12) was developed. The precursor of the sintering additive was formed by the method of spray drying using a mixture of colloidal solutions of Al5(NO3)3(OH)12 and Y(OH)2(CH3COO). The produced mixture samples were studied by X-ray diffraction analysis and SEM. The kinetics of the SPS of the prepared mixtures was studied. The effect of preliminary annealing (up to 1000 °C) of the mixture on the formation of the YAG sintering additive have been considered, as well as the method of reactive synthesis of the sintering additive in the SPS process. It was found out that sintering of the annealed mixture does not allow forming high density ceramics. As a result of reactive sintering, ceramics based on Si2N2O were formed.
Laser fusion of aluminum-alumina composites obtained in the vortex layer apparatus
Authors: Nalivaiko A , Ozherelkov D , Morozova A , Shinkaryov A , Gromov A 
Published: January 2021

Abstract
The current study is devoted to laser fusion of aluminum-matrix composites with 3 wt. % of alumina obtained in the vortex layer apparatus. The mixing parameters and the distribution of alumina in the composite structure were studied. Three parameters of laser fusion for plate synthesis were used. The finest results were achieved using a volumetric energy density of 24 J/mm3 with 370 W laser power. The maximum mechanical properties of the samples synthesized by the optimal parameters were: UTS = 384 ± 5 MPa; Ef = 0.54 ± 0.1 %.
On the formation of AlSiMgCu/quasicrystal powder composite single tracks by selective laser melting
Authors: Ozherelkov D Yu , Nalivaiko A Yu , Gromov A A , Solodov D O , Komissarov A A , Shinkaryov A S , Morozova A I 
Published: January 2021

Abstract
The process of selective laser melting (SLM) of an Al-Si-Mg-Cu powder composite with the addition of quasicrystal reinforcements under conditions of a limited powder amount was investigated. The morphology and microhardness of the obtained scan single tracks were discussed, and the optimal sintering parameters were found to be in the Linear Energy Density (LED) range 0.21-0.30 J/mm. The following SLM parameters: P = 370 W and v = 1650 mm/s given the optimal characteristics of scan single tracks geometry with less defects. The obtained composites exhibited an improved hardness with the highest values of 235 HV with the 8% of reinforcements in the powder mixture.
Structure formation of titanium alloys during vacuum-arc surfacing
Authors: Permyakov G L , Olshanskaya T V , Krivonosova E A , Trushnikov D N 
Published: January 2021

Abstract
The work is based on wire vacuum-arc surfacing as one of the technologies for additive manufacturing. The results of the formation of structure and properties of a high-temperature titanium alloy of the Ti-Al-V-Mo-Zr system during vacuum-arc surfacing are presented. The structure of the surfaced materials consists of dendritic grains that are oriented in the direction opposite to heat removal. Some banding of the structure is observed. There is no porosity in the deposited layers for all surfacing modes. It was determined that a decrease in the surfacing current promotes an increase in the dispersion of the α-phase plates, which is accompanied by an increase in microhardness. With such a thermal cycle of surfacing, conditions are created for the formation of a favorable fine-dispersed martensitic structure with narrow α-colonies of small needles of the α-phase, providing a high microhardness at the level of 400HV.
Study of phase formation and properties of high-entropy carbide HfTaTiNbZrC5 obtained by selfpropagating high-temperature synthesis
Authors: Sedegov A S , Bobojanov A R , Vorotilo S , Kuskov K V , Moscovskikh D O 
Published: January 2021

Abstract
This work is devoted to the study of the combustion synthesis mechanism in complex multi-component systems using the quenching of the combustion front in a copper block. Bulk specimens were produced by reactive spark plasma sintering (R-SPS) of mechanically activated mixtures as well as by SPS of high-entropy ceramics obtained by combustion synthesis. The resistance of high-entropy carbides towards oxidation was studied in relation to the number of metallic constituents.
Effect of carbon content, deformation and annealing on the structure and properties of interstitial TRIP high-entropy alloys
Authors: Shaysultanov D G , Raimov K Sh , Stepanov N D 
Published: January 2021

Abstract
In this work, the effect of carbon content on the structure and mechanical properties of Fe(50-x)Mn30Co10Cr10Cx (x=0; 0.5; 1.0 at.%) interstitial high entropy alloys was studied. In the as-cast condition, the alloys were composed of the face centred cubic (fcc) and hexagonal close packed (hcp) phases; the amount of the hcp phase decreased from 46% to 20% as the carbon concentration increased from 0 to 1 at.%. The carbon content had a limited effect on the strength of the alloys, yet the ductility was enhanced significantly as the result of interstitial alloying. Furthermore, Fe49Mn30Co10Cr10C1 alloy was cold rolled to a reduction of 56% reduction and annealed at 700-900°C for 1 hour. After cold working, the alloy has attained almost fully the hcp structure. Annealing resulted in (i) transformation of the deformation-induced hcp phase into fcc; (ii) development of recovery and recrystallization; (iii) precipitation of Cr-rich M23C6 carbides. The cold-rolled alloy was very strong but brittle; annealing resulted in softening and increase of the ductility. The relationships between the chemical composition, structure and mechanical properties of the alloys are briefly discussed.
Synthesis of the high-entropy (BiSbSe1.5Te1.5)1-x
Cu
x
compound promising for thermoelectric applications
Authors: Vasil’ev A E , Yaprintsev M N , Ivanov O N , Zhezhu M V , Yapryntseva E N 
Published: January 2021

Abstract
Single phase and nanosized powders of high-entropy (BiSbSe1.5Te1.5)1-x
Cu
x
compound with x=0; 0.3, 0.6 were synthesized by using soft chemistry approaches. Owing to its low thermal conductivity, this compound is promising for thermoelectric applications. The synthesized powders were used to prepare bulk samples totally suitable for testing thermoelectric properties.
Structure and mechanical properties of near-eutectic refractory Al-Cr-Nb-Ti-Zr high entropy alloys
Authors: Yurchenko N , Panina E , Salishchev G , Stepanov N 
Published: January 2021

Abstract
In this study, the structure and mechanical properties of the near-eutectic refractory Al24Cr11Nb11Ti37Zr17, Al20Cr20Nb25Ti25Zr10, and Al28Cr15Nb15Ti20Zr22 (at.%) high entropy alloys were investigated. Both the Al24Cr11Nb11Ti37Zr17 and Al20Cr20Nb25Ti25Zr10 alloys had a hypoeutectic structure, while the Al28Cr15Nb15Ti20Zr22 alloy had a hypereutectic one. The proeutectic phase in the Al24Cr11Nb11Ti37Zr17 and Al20Cr20Nb25Ti25Zr10 alloys was the ordered B2 phase and in the Al28Cr15Nb15Ti20Zr22 alloy – the C14 Laves phase. In all three alloys, the eutectic regions possessed a fine lamellar structure composed of a mixture of the C14 Laves and B2 phases. The densities of the alloys were 5.20-5.89 g/cm3. The Al24Cr11Nb11Ti37Zr17 and Al28Cr15Nb15Ti20Zr22 alloys were extremely brittle at 22°C, while the Al20Cr20Nb25Ti25Zr10 alloy showed some ductility (ε = 0.7%) and high yield strength of 1830 MPa. At 800°C, all alloys became ductile. The highest yield strength (1010 MPa) was demonstrated by the Al20Cr20Nb25Ti25Zr10 alloy and the lowest one (235 MPa) – by the Al24Cr11Nb11Ti37Zr17 alloy. The comparison between the experimental as-solidified structures and the CALPHAD predictions was made.
Nanoscale structural evolution of Al2Cu precipitates in friction-stir welded Al–Cu–Mg alloy
Authors: Zuiko I , Malopheyev S , Mironov S , Kaibyshev R 
Published: January 2021

Abstract
The work is devoted to FSW of cold rolled AA2519. The non-uniform distribution of all second phase precipitates (including coherent θ″ and non-coherent θ) was shown via the TEM-technique. The nucleation of the stable θ-phase, along with decreased dislocation density, led to a drop (∼60 HV0.2) in the microhardness of the nugget zone.
Robotized assembly and inspection of composite fuselage panels: the LABOR project approach
Authors: Caterino Mario , Chiacchio Pasquale , Cristalli Cristina , Fera Marcello , Lettera Gaetano , Natale Ciro , Nisi Matteo 
Published: January 2021

Abstract
The aerospace manufacturing is looking at ways to change their production processes in order to improve costs, flexibility and efficiency. The LABOR project, acronym for Lean robotized AssemBly and cOntrol of composite aeRostructures, aims at introducing robotic solutions for the assembly line of fuselage panels adopting medium size robots equipped with smart tools, Human Robot collaboration approach and a distributed software architecture. The system consists of a jig that holds the panel to be assembled, two 6-axis robots mounted on moving platforms in order to reach the whole panel and real time measurements to perform the quality control of the assembled components. The cell automatically performs the referencing of the robot working area on the basis of the recognition of geometric features of the parts to be coupled (edges, holes, etc.) through the use of 3D smart inspection tools. After the ”one shot” drilling and countersinking operations, the hole is processed to guarantee a high standard of the process. Installation and sealing of the fastener complete the working cycle. Furthermore, an advanced multimodal perception system monitors the collaborative workspace in real time for safe human-robot collaboration (HRC) tasks. The project started in March 2018 as part of the European Clean Sky 2 research program. Three partners – LOCCIONI, UNICAMPANIA and UNISA – are developing the prototype cell in collaboration with LEONARDO S.P.A. that is the Topic Manager.
Development and trend of unified mechanism-based materials modelling for creep age forming of aluminium alloys
Authors: Wang Xi , Li Yong , Chen Baoguo , Shi Zhusheng 
Published: January 2021

Abstract
Materials modelling plays an important role for sprinback compensation and tool surface design in creep age forming (CAF). This review aims to provide perspective on the development and trend of materials modelling for CAF of aluminium alloys. Recently proposed unified constitutive equations for creep-ageing behaviour of aluminium alloys during CAF by integrating microstructural evolution and hardening effects are reviewed. The modelling methods and developing trend to quantitively reflect the relationship between the microstructural evolutions and macro creep-ageing behaviour of materials during CAF are discussed.
Integration and evaluation of a meander-shaped fibre-optical sensor in GFRP coupons
Authors: Preisler A , Wolf-Monheim F , Kaiser D , Wojtczyk R , Dafnis A , Schröder K-U , David W , Zandbergen P 
Published: January 2021

Abstract
Fibre-reinforced plastics are attracting more and more attention also in non-aviation sectors. The possible formation of internal damage and its difficult detection thus simultaneously increases the need for structural health monitoring. In this case especially fibre-optical sensors possess an enormous potential. In the previous work the use of a meander-shaped sensor layout was proposed, utilizing strain in longitudinal direction for loads monitoring and distinct measuring sections in zero-strain direction for structural health monitoring. In the present work, the proposed meander-shaped sensor layout is integrated inside unidirectional coupons using tailored fibre placement. Further samples without a sensor and samples with a straight sensor-fibre were also manufactured as a reference. The influence of the sensor on the static strength and stiffness is then examined in a test campaign using a three-point bending setup. In addition, the functionality of the meander-shaped sensor layout is validated.
Investigation on low velocity impact damage identification with ultrasonic techniques under different sensor network conditions
Authors: Beligni A , Cadini F , Sbarufatti C , Giglio M , Cimminiello N , Salvato P , Monaco E , Romano F 
Published: January 2021

Abstract
Direct or indirect damages due to foreign object impacts on aeronautical structures, represent a major concern. The problem potentially intensifies with the adoption of composite materials, especially due to Barely Visible Impact Damage (BVID). In this context, understanding whether an impact event gives rise to delamination or debonding is highly desirable in view of the optimization of the maintenance strategies and, at the same time, of the safety margins associated to the operation of the structures. One possible method to achieve this goal is that of integrating damage monitoring systems within the vehicle architecture itself. By doing so, in fact, the enhanced structural health state awareness allows the implementation of Predictive Maintenance philosophies and the possibility to detect damage with size/severity and indentation smaller than the BVID currently applied by design and certification. In this work, a simple and a stiffened carbon fiber panel are subjected to Low Velocity Impacts using falling masses to generate a structural damage. A sensor network made of Piezoelectric elements (PZT) allows the application of Ultrasonic techniques, to monitor the damaged structure and calculate signal related features called Damage Indexes (DIs). The DI capability to identify the damage is then thoroughly investigated, with specific reference to: (i) effect of signal averaging, (ii) effect of reduced sensor network configurations and (iii) effect of sensor faults.
Eddy Current and Quantum Well Effect Eddy Current Field Measurement of Carbon Fibre Raw Materials and cured parts in the Aerospace Industry
Authors: Silva C , James V , Smith C , Hansen J , Missous M , Sexton J , Watson J , Dobson J 
Published: January 2021

Abstract
The composite industry requires a fast and couplant free NDT methodology. The C-Flux project spearheaded by M Wright & Sons Ltd (MWS) and TWI Wales, is tackling these requirements with the development of Eddy Current NDT system developed by ETher NDE and quantum well effect eddy current field measurement (QW-ECFM) NDT system developed by AHS. FAR UK and MWS are supplying to the project standard and flawed carbon fibre composite parts up 20mm thick to refine these electromagnetic techniques. TWI is developing automated apparatuses to deploy these NDT systems for the aerospace industry.
Mesh-diverging inviscid adjoint solutions
Authors: Lozano Carlos , Ponsin Jorge 
Published: January 2021

Abstract
This paper describes a surprising problem encountered in the numerical solution of the Adjoint Euler equations. The basic result presented here is that certain two and three dimensional numerical solutions to the adjoint Euler equations have a value at and near the surface of wings and airfoils that depends strongly on the mesh density and which does not converge as the mesh is refined. The purpose of this paper is to characterize this problem and offer insights as to the possible explanation of this unusual behavior.
Steady and Unsteady RANS Modeling of Wake Effects and Grid Resolution Requirements in a Low-Pressure Turbine Cascade
Authors: Führing Alexander , Kožulovic Dragan , Bode Christoph , Franke Matthias 
Published: January 2021

Abstract
Due to relative motion between rotors and stators in aircraft engines, periodic wakes are present in downstream blade rows, which exert significant influence at flow loss and engine efficiency. To quantify and reproduce this influence, a low-pressure turbine cascade is computed using steady and unsteady RANS methods in the flow solver TRACE by DLR and MTU Aero Engines. A thorough grid study is carried out and various aspects of grid resolution requirements are investigated for the setups and considered performance metrics respectively. A steady state transition model extension that has been developed and published by the authors is applied to the cascade flow at a number of operating points and validated with experimental data while being compared to the unsteady results as well as the steady state results without the wake effect extension. Further, a variation of wake-related parameters is carried out while discussing the effects modeled in the unsteady setup as well as the ability of the two steady state setups (with and without wake extension) to capture the trends identified by the unsteady results. A sufficiently accurate reproduction by the wake model extension enables steady simulations of the inherently unsteady effects in the aerodynamic design of the turbine, which results in an enormous saving of computational time and effort.
Development of a Cargo Airdrop Modeling Method for a Tactical Blended-Wing-Body UAV
Authors: Mitridis D. , Mathioudakis N. , Panagiotou P. , Yakinthos K. 
Published: January 2021

Abstract
In this paper, the development of a cargo airdrop modeling method is presented for a fixed-wing tactical UAV. The UAV, which is being developed in the framework of the DELAER UAS project, is based on the Blended-Wing-Body layout, and its mission is to deliver cargo and lifesaving supplies via airdrop, to remote and isolated Greek territories as well as over isolated islands in the Aegean Sea. At first, a simplified kinematic model is developed, to describe the trajectory of the cargo. Then, the critical airdrop parameters, such as the aerodynamic drag and the effect of wind gusts, are identified and incorporated to the model. Based on this model, an analysis methodology is proposed, conducted in several simulation loops. In each simulation loop, the cargo mass, release height, drop velocity and wind gust speed are the main variables. The results are given in a form of scatter plots, depicting the simulated cargo airdrop positions on the ground (or sea), around an actual target location, with respect to the drop height, drop velocity and wing magnitude. A solid conclusion is that, by releasing the cargo box with tailwind, the accuracy of the airdrop can be improved as much as 67% compared to any other wind direction.