bluuebunny/crossref_metadata_2025 huggingface dataset:
A GPR-based emulator for semi-numerical reionization code SCRIPT: parameter inference from 21 cm data
Authors: Choudhury T. Roy , Paranjape A. , Maity B.
Published: March 2024

Semi-numerical models of reionization typically involve a large number of unknown
parameters whose values are constrained by comparing with observations. Increasingly often,
exploring this parameter space using semi-numerical simulations can become computationally
intensive, thus necessitating the use of emulators. In this work, we present a likelihood emulator
based on Gaussian Process Regression (GPR) for our semi-numerical reionization code,
SCRIPT, and use it for parameter inference using mock 21 cm power spectrum data and
Bayesian MCMC analysis. A unique aspect of our methodology is the utilization of coarse resolution
simulations to identify high-probability regions within the parameter space, employing only a
moderate amount of computational time. Samples drawn from these high-probability regions are used
to construct the training set for the emulator. The subsequent MCMC using this GPR-trained
emulator is found to provide parameter posteriors that agree reasonably well with those obtained
using conventional MCMC. The computing time for the analysis, which includes both generation of
training sets and training the emulator, is reduced by approximately an order of magnitude. This
methodology is particularly advantageous in scenarios where one wants to use different
parametrizations of reionization models and/or needs to start with broad prior distributions on
the parameters, offering an efficient and effective means of parameter inference.
Prediction of collapse process and tipping points for mutualistic and competitive networks with k-core method
Authors: Duan 段 Dongli 东立 , Bi 毕 Feifei 菲菲 , Li 李 Sifan 思凡 , Wu 吴 Chengxing 成星 , Lv 吕 Changchun 长春 , Cai 蔡 Zhiqiang 志强
Published: March 2024

Ecosystems generally have the self-adapting ability to resist various external pressures or disturbances, which is always called resilience. However, once the external disturbances exceed the tipping points of the system resilience, the consequences would be catastrophic, and eventually lead the ecosystem to complete collapse. We capture the collapse process of ecosystems represented by plant-pollinator networks with the k-core nested structural method, and find that a sufficiently weak interaction strength or a sufficiently large competition weight can cause the structure of the ecosystem to collapse from its smallest k-core towards its largest k-core. Then we give the tipping points of structure and dynamic collapse of the entire system from the one-dimensional dynamic function of the ecosystem. Our work provides an intuitive and precise description of the dynamic process of ecosystem collapse under multiple interactions, and provides theoretical insights into further avoiding the occurrence of ecosystem collapse.
Optimize Purcell filter design for reducing influence of fabrication variation
Authors: Cai 蔡 Xiao 晓 , Zhou 周 Yi-Biao 翼彪 , Yu 于 Wen-Long 文龙 , Xiong 熊 Kang-Lin 康林 , Feng 冯 Jia-Gui 加贵
Published: March 2024

To protect superconducting qubits and enable rapid readout, optimally designed Purcell filters are essential. To suppress the off-resonant driving of untargeted readout resonators, individual Purcell filters are used for each readout resonator. However, achieving consistent frequency between a readout resonator and a Purcell filter is a significant challenge. A systematic computational analysis is conducted to investigate how fabrication variation affects filter performance, through focusing on the coupling capacitor structure and coplanar waveguide (CPW) transmission line specifications. The results indicate that the T-type enclosing capacitor (EC), which exhibits lower structural sensitivity, is more advantageous for achieving target capacitance than the C-type EC and the interdigital capacitor (IDC). By utilizing a large-sized CPW with the T-type EC structure, fluctuations in the effective coupling strength can be reduced to 10%, given typical micro-nanofabrication variances. The numerical simulations presented in this work minimize the influence of fabrication deviations, thereby significantly improving the reliability of Purcell filter designs.
Machine Learning-based Identification of Contaminated Images in Light Curve Data Preprocessing
Authors: Li Hui , Li Rong-Wang , Shu Peng , Li Yu-Qiang
Published: March 2024

Attitude is one of the crucial parameters for space objects and plays a vital role in collision prediction and debris removal. Analyzing light curves to determine attitude is the most commonly used method. In photometric observations, outliers may exist in the obtained light curves due to various reasons. Therefore, preprocessing is required to remove these outliers to obtain high quality light curves. Through statistical analysis, the reasons leading to outliers can be categorized into two main types: first, the brightness of the object significantly increases due to the passage of a star nearby, referred to as “stellar contamination,” and second, the brightness markedly decreases due to cloudy cover, referred to as “cloudy contamination.” The traditional approach of manually inspecting images for contamination is time-consuming and labor-intensive. However, we propose the utilization of machine learning methods as a substitute. Convolutional Neural Networks and SVMs are employed to identify cases of stellar contamination and cloudy contamination, achieving F1 scores of 1.00 and 0.98 on a test set, respectively. We also explore other machine learning methods such as ResNet-18 and Light Gradient Boosting Machine, then conduct comparative analyses of the results.
Online Bayesian optimization of vagus nerve stimulation
Authors: Wernisch Lorenz , Edwards Tristan , Berthon Antonin , Tessier-Lariviere Olivier , Sarkans Elvijs , Stoukidi Myrta , Fortier-Poisson Pascal , Pinkney Max , Thornton Michael , Hanley Catherine , Lee Susannah , Jennings Joel , Appleton Ben , Garsed Phillip , Patterson Bret , Buttinger Will , Gonshaw Samuel , Jakopec Matjaž , Shunmugam Sudhakaran , Mamen Jorin , Tukiainen Aleksi , Lajoie Guillaume , Armitage Oliver , Hewage Emil
Published: March 2024

Objective. In bioelectronic medicine, neuromodulation therapies induce neural signals to the brain or organs, modifying their function. Stimulation devices capable of triggering exogenous neural signals using electrical waveforms require a complex and multi-dimensional parameter space to control such waveforms. Determining the best combination of parameters (waveform optimization or dosing) for treating a particular patient’s illness is therefore challenging. Comprehensive parameter searching for an optimal stimulation effect is often infeasible in a clinical setting due to the size of the parameter space. Restricting this space, however, may lead to suboptimal therapeutic results, reduced responder rates, and adverse effects. Approach. As an alternative to a full parameter search, we present a flexible machine learning, data acquisition, and processing framework for optimizing neural stimulation parameters, requiring as few steps as possible using Bayesian optimization. This optimization builds a model of the neural and physiological responses to stimulations, enabling it to optimize stimulation parameters and provide estimates of the accuracy of the response model. The vagus nerve (VN) innervates, among other thoracic and visceral organs, the heart, thus controlling heart rate (HR), making it an ideal candidate for demonstrating the effectiveness of our approach. Main results. The efficacy of our optimization approach was first evaluated on simulated neural responses, then applied to VN stimulation intraoperatively in porcine subjects. Optimization converged quickly on parameters achieving target HRs and optimizing neural B-fiber activations despite high intersubject variability. Significance. An optimized stimulation waveform was achieved in real time with far fewer stimulations than required by alternative optimization strategies, thus minimizing exposure to side effects. Uncertainty estimates helped avoiding stimulations outside a safe range. Our approach shows that a complex set of neural stimulation parameters can be optimized in real-time for a patient to achieve a personalized precision dosing.
A New Type of Expanded Graphite-Based Heat-Conducting Glue and Its Application in Heat-Non-Burning Cigarette
Authors: Chen Wenting , Li Yufei , Zhang Yining , Liu Yuantao , Li Lu , Gao Cheng , Li Dian , Liu Jialei
Published: March 2024

With the popularity of heat non-combustible cigarettes, a new type of tobacco product, higher requirements have been put forward for the thermal conductivity of tobacco materials compared to traditional tobacco. In order to make the tobacco uniformly heated, adding high thermal conductivity materials to the tobacco to improve the thermal conductivity of the tobacco in the heat-non-burning smoke is a conventional practice. Therefore, this article introduces expanded graphite with high specific surface area and high thermal conductivity as the main material of thermal conductivity, and the polymer obtained by esterification reaction of biomass material polylactic acid, citric acid and diol are utilized as the adhesive glue. Research shows that this material enhances the heating performance of tobacco in heat non-combustible cigarettes. The thermal conductivity measured by adding 3 ml, 4 ml, and 6 ml of the expanded graphite viscous mixture to the filter paper spacer increased sequentially both at room temperature and at 100 degrees Celsius, and all of them were higher than that of the blank filter paper. This method effectively realized the fixation of the expanded graphite thermal conductive material on the surface of the tobacco, which greatly improved the thermal conductivity performance of the tobacco and made this new type of heat cigarettes more uniformly heated.
Preparation and Ferroelectric Properties of Er Doped BaTiO3 Nanotubes
Authors: Wu Chengjun , Song Haibo , Dai Xinchao , Qiu Shuang , Deng Xiangyun
Published: March 2024

In this paper, erbium-doped barium titanate nanotubes with different concentrations were prepared by combining the anodic oxidation method with the low-temperature hydrothermal method. The TiO2 nanotubes produced by electrolysis using titanium flakes as substrate were put into barium hydroxide octahydrate solution for hydrothermal reaction, and different concentrations of Er-doped barium titanate nanotubes were prepared by adding different concentrations of Er(NO3)3·5H2O to the reaction solution. The samples with different doping concentrations were analyzed for their morphological structure, physical phase composition and ferroelectric properties. All samples were found to have complete barium titanate nanotube structure, and the diffraction peaks of XRD were compared with the standard Cope, and the doped samples were all tetragonal phase chalcogenide structure with no other impurities generated. From the hysteresis loop diagram of the samples measured by the TF-2000 ferroelectric analyzer, it can be found that the residual polarization intensity of the samples showed a characteristic of increasing and then decreasing with the increase of the doping concentration, and the residual polarization intensity was the largest at 0.151 uC/cm2 under the hydrothermal reaction condition of 180°C and 3 h with the Er3+ concentration of 0.0025 mol/L.
Fe Single-Atoms Combined with Chitosan for Enhanced Electromagnetic Wave Absorption
Authors: Cao Kunyao , Xue Weidong , Zhao Rui
Published: March 2024

On account of that the single carbon material possess exceeding electrical conductivity, which will cause impedance mismatch and thus seriously affects the electromagnetic wave (EMW) absorption performance of the material. Therefore, it is an effective method to combine carbon material with magnetic material to make the material have dielectric loss and magnetic loss at the same time. In this paper, magnetic Fe nanospheres were loaded onto the conductive network of chitosan and the composite 800Fe-Chitosan was obtained through freeze drying and calcination treatment. As a result, the composite shows superior EMW absorption performance with a reflection loss (RL) of -40.22 dB and a broad effective absorption bandwidth (EAB) of 4.24 GHz.
Structural Design and Life Prediction of Sheet Metal Parts for Gas Turbine Vane
Authors: Lan Jibing , Dai Bin , Wei Jiaming , Yao Wendan , Yu Peijiong
Published: March 2024

In the cooling design of gas turbine vane, sheet metal parts were used to arrange the impact cooling holes in the platform and inner cavity, and divided the chamber space for impact cooling. During the service period, due to the impact of temperature load and air flow, the sheet metal parts were prone to bulge, crack, fall off, which worsen the cooling effect. In order to ensure the safe and reliable operation of blade and sheet metal parts, it was necessary to design reasonable sheet metal structure and accurately predict the service life. In this paper, material mechanical property test of GH3536 was carried out to obtain its constitutive equation and fatigue performance parameters. The structure of sheet metal parts were designed, then the temperature field of the blade and the sheet metal was simulated by using the fluid-thermal-solid coupling method, and the stress-strain analysis was carried out by using the elastic-plastic constitutive model. Finally, the fatigue life of the sheet metal was obtained, and the service life meet the design requirements. This work was helpful to prolong the life of sheet metal structure and ensure the cooling effect of blade.
Electrical Property Improvements of Multiple Dopant ZnO/Bi2O3 Varistor By Liquid Phase Method
Authors: Wang Lei , Xu Jinxia , Sun Yi , Song Xingjuan , Liu Lingyun
Published: March 2024

Although ZnO Varistor is widely used in surge protection due to its unique I-V characteristics, its key influencing factors of grain size and uniformity are difficult to be guaranteed by traditional solid phase method. In this paper, the ZnO/Bi2O3 varistor was prepared by liquid phase co-deposition method and the sintering temperature also has been optimized. For samples prepared by the liquid-phase method, as the sintering temperature increases, the grain size gradually increases, the grain distribution becomes initially more uniform and later more disordered, and the crystallinity gradually increases. In comparison to solid-phase method, samples prepared by liquid-phase method exhibit smaller grain sizes and more uniform grain size distribution. Based on this, samples sintered at 1100 °C by the liquid-phase method demonstrate optimal electrical performance: the voltage gradient is 520 V/mm, the nonlinear coefficient is 44, and the leakage current is 5.8 μA/cm2. This paper has theoretical support for the study of preparation of varistor for achieving excellent electrical performance for being used in the field of surge protection.
Protective Effects of Collagen Peptide on Periodontal Ligament Fibroblasts
Authors: Yan Zheng , Jiang Bin , Dong Peng , Wang Haiyan
Published: March 2024

To study the protective effect of collagen peptide on human periodontal ligament fibroblasts (hPDLFs) induced by lipopolysaccharide and its possible mechanism. Lipopoly-saccharide was used as a pathogenic factor to stimulate hPDLFs. Then, interleukin-8 and tumor necrosis factor-α in the supernatant were quantified, and Toll-like receptor 4 expression and the activation of nuclear factor-κB pathway were also studied. The results showed that collagen peptide above 100 mg/L could effectively reduce the toxicity of lipopolysaccharide, and significantly reduce interleukin-8 and tumor necrosis factor-α produced by lipopolysaccharide. Suggesting that collagen peptide can provide effecitve and safe solution to oral cavity repair.
Condition Evaluation and Replacement Method of Damp Cable
Authors: Wang Lei , Niu Lin , Zhang Zhenhai , Guo Lijuan , Chen Lina , Zhang Bingqian
Published: March 2024

Cable lines are now being widely used. According to statistics data, cable dampness is the main factor affecting the operation of cable lines at present. If the cables are damp, evaluate the degree of damp and replace the cables that are severely damp in sequence. In this paper, the physical and chemical properties, mechanical properties and dielectric properties of the cable are used to evaluate the status of the cable. By comparing the length and carrying capacity of cables in operation, the degree of damp was sorted by skyline algorithm, and the most serious cables were replaced first.
Influence of Filler/Binder Ratio on the Fatigue Behavior of Epoxy Asphalt Concrete
Authors: Li Kuan , Xie Jianguang , Pan Youqiang
Published: March 2024

To further explore the influence of the filler/binder (F/B) ratio on the fatigue behavior of epoxy asphalt concrete (EAC), in this study, three typical F/B ratios are designed according to the EAC pavement of steel bridges in China, including 1.49, 1.95 and 2.48. The four-point fatigue behavior of the EAC with various F/B ratios was tested and analyzed. The results show that a higher F/B ratio leads a more rapid increase in the ratio of dissipated energy change (RDEC) during limited loading repetitions, as well as an increased likelihood of irreversible damage and a shorter fatigue life for the EAC. To ensure adequate fatigue performance of the EAC, it is recommended that the F/B ratio be controlled below 1.95.
Analysis of Buckling Property of Portal Steel Plate Shear Wall Member Used for Steel Frame
Authors: Shi Yaying , Wang Huake , Duan Yuezhen , Wang Xintang
Published: March 2024

A set of portal steel plate shear wall members are numerically studied, and effect of some factors on its buckling property and stiffeners used for avoiding its buckling is especially discussed. It is concluded that three stiffening forms presented here have a better effect on the buckling performance of the portal steel plate shear wall member. The buckling coefficient of various portal steel plate shear walls with 6m span are slightly lower than those with 4m and 5m span, which means that the increase of span will reduce the buckling performance and out of plane instability bearing performance of portal steel plate shear walls studied here. The buckling performance requirements can be met by using the stiffening form I as if thickness of the portal steel plate shear wall take as 16mm for the stell framed structures below 10 stories.
Microstructure and Mechanical Properties of Cermet Composite Coating on TC4 Surface
Authors: Zheng Lijuan , Xie Yinkai , Zhang Kuo , Fu Yuming
Published: March 2024

In order to improve the surface quality and performance of TC4, the TC4-HfC-TaC metal-ceramic composite cladding coating was prepared on the surface of TC4 by using different process parameters by laser cladding technology. Through digital testing equipment, the macro morphology, molten pool size, dilution rate, Rockwell hardness (HRC), geometry, microstructure and other comprehensive properties of the coating are studied and analyzed. The results show that the performance characterization of TC4-HfC-TaC cladding layer is closely related to the melting state of refractory carbide ceramic phase HfC and TaC powder, when the laser beam energy density is not enough to completely melt the ceramic phase powder, with the increase of energy density, the coating surface tends to be flat, the molten pool size and dilution rate increase, the hardness gradually increases, the metallographic structure is refined uniformly, and the surface quality is improved. Excessive energy density of the laser beam can easily lead to excessive dilution rate of the cladding layer, reduced coating hardness, coarse metallographic structure, and reduced surface quality. Finally, the best combination of process parameters was screened out: laser power 3000 W, scanning speed 300 mm/min, spot size 2.5 × 11.5 mm, rectangular spot lap rate 40%, preset powder thickness 1.5 mm, at which time the coating hardness increased to 63.22 HRC. It is about 2.1 times the hardness of TC4 substrate, with the best performance, and the metallographic structure is densely arranged fine cell-like crystals, with outstanding microscopic characteristics, which realizes the purpose of preparing high-quality TC4-HfC-TaC cermet composite cladding coating on the surface of TC4 titanium alloy.
Study on Crystallinity and Magnetic Properties of NiCuZn Ferrite Films Deposited by RF Sputtering
Authors: Zhou Zhen , He Jing
Published: March 2024

Nickel-zinc ferrite proves to be the top-performing material in terms of soft magnetic features for high-frequency applications. The purpose of this study is to explore the impact of various factors such as sputtering pressure, substrate temperature, sputtering power, and sputtering gas, on the magnetic and structural properties of NiCuZn ferrite thin films. In this research, radio-frequency magnetron sputtering of NiCuZn ferrite thin films on silicon substrates was used to investigate the matter. The study demonstrates that reducing sputtering pressure enhances the crystallization of NiCuZn ferrite films and improves their magnetic properties. The saturation magnetization and crystallinity of the thin films initially increased, then decreased as substrate temperature and sputtering power increased. Furthermore, the sputtered films exhibited higher crystallinity and saturation magnetization in a pure Ar atmosphere compared to an oxygen-containing environment. In this study, we optimized the sputtering parameters to achieve a maximum saturation magnetization strength of 253 emu/cc.
Seismic Response Analysis of Multi Span Hyperbolic Brick Arch Thin Shell Structure
Authors: Si Jianhui , Ma Peiyuan , Niu Xiaoyu , Ju Junpeng , Zhou Ming , He Lizhe , Wang Yi , MajidKhan Abdul
Published: March 2024

The research objective is to investigate the multi-span hyperbolic brick arch thin-shell structure located in Changleyuan, Baoji City, Shaanxi Province. The study utilizes on-site dynamic testing and finite element numerical simulation methods to analyze the dynamic characteristics of the thin-shell structure and its seismic response under various seismic waves and directions. The simulation results indicate the following findings: Vertical earthquakes cause more severe damage to structures compared to horizontal earthquakes. Bidirectional seismic excitation has a greater impact on the structure than unidirectional and three-dimensional seismic excitation. The obtained results provide a scientific basis for the seismic protection, reinforcement, and repair of this multi-span double-curved brick arch thin-shell structure.
Research on Mode Switching and Energy Management of Hybrid Electric Vehicle
Authors: Tang Chuanyin , Pan Bingyu , Wu Longjie , Li Jinghong , Wei Meirong
Published: March 2024

Aiming at the optimization of mode switching control and energy management strategy for parallel hybrid electric vehicles, a mode switching control method and A-ECMS steady-state energy management strategy is proposed. Firstly, in order to effectively suppress the impact caused by mode switching, and a fuzzy controller is designed for clutch engagement displacement. Then, on the basis of ensuring the smoothness of mode switching, A-ECMS control strategy based on SOC feedback is established. Finally, Isight and Cruise are used to build a co-simulation platform, and multi-island genetic algorithm is used to study the influence of initial value selection of equivalent factor on the controller. The results show that the proposed mode switching control and energy management control strategy, combined with A-ECMS strategy, can effectively improve the vehicle fuel economy on the basis of ensuring the mode switching smoothness.
Effects of Selenium Ions on the Growth of Rice Seedlings
Authors: Li Feng , Yao Yushuang , Guo Weichao , Wu Zhengwei , Yang Shaoxia , Liu Ying
Published: March 2024

For investigating the effect of selenium on the growth of rice seedlings, this study used different concentrations of selenium ions (0, 0.5, 5, 10 and 20 µmol/L) to treat rice seedlings hydroponically. The experimental findings demonstrated that rice seedlings could grow and develop properly in the presence of a selenium deficiency (0 mol/L). Selenium ions had a positive impact on the development of rice seedlings at low and middle selenium concentrations of 0.5 mol/L and 5 mol/L, boosting plant height, above-ground fresh and dry weights. Selenium ions had a substantial inhibitory impact on the development of rice seedlings at high selenium concentrations of 10 mol/L and 20 mol/L.
Efficient Removal of Trivalent Iron and Sulfate from Coal Mine Gushing Water Using Zero-Valent Iron Powder Combined with Hydrogen Peroxide
Authors: Chen Junwen , Chen Jiancheng , Li Qiongyao , Tang Binlin , Gu Chunyao , Gan Min , Zhu Jianyu , Jiang Zongman
Published: March 2024

The high concentration of trivalent iron (Fe3+) and sulfate (SO4
2-) ions in coal mine gushing water is a major ecological hazard and difficult to treat industrially. In this paper, effective purification of coal mine gushing water was achieved by the two-step cyclic process using zero-valent iron (ZVI) powder and hydrogen peroxide. We investigated the effect of different doses of ZVI and hydrogen peroxide on the removal of Fe3+ and SO4
2-. Single-factor experiments indicated that as the dosage of ZVI increased, the removal of Fe3+ increased and then decreased, with the highest Fe3+ removal rate approaching 100% at the ZVI dosage of 100 mg/L, while the maximum removal rate of SO4
2- for sulphate was achieved at 400 ppm of hydrogen peroxide. The precipitate produced in the purification system was characterized and the results demonstrated that it was a typical secondary mineral, schwertmannite, and that it contained considerably more iron and sulfate than the precipitate formed by the natural sedimentation process in coal mine gushing water. Overall, after the two-step cycle process, Fe3+ and SO4
2- can be effectively removed via the formation of schwertmannite, and the ion concentrations all meet the discharge standards for Chinese mining industry wastewater.
Early Identification of Geological Disasters in Loess Hilly Area of Ningnan Based on InSAR Technology: A case study of Yuanzhou District, China
Authors: Wang Hui , Zhang Jia , Gong Yongfeng , Wang Guorui , Hu Zhiyong
Published: March 2024

Using small baseline subset InSAR (SBAS-InSAR) technology and multi-temporal synthetic aperture radar data, multitemporal phase and long-term sequential deformation monitoring and early identification of geological hazards were carried out in the loess hilly area of southern Ningnan-Yuanzhou area. Based on the analysis of radar visibility in the loess hilly area of southern Ningxia. The Sentinel-1A historical archived data of 36 periods from January 2019–December 2021 and descending orbit data from January 2019–May 2021 were used to carry out monitoring of surface deformation in the river basin, and a total of 61 hidden danger. 49 new concealed high risk points were identified by comprehensive optical remote sensing interpretation. The annual average deformation rate of the radar line-of-sight direction of the ascent data was -47.6746–71.6472mm/a, and the cumulative deformation variable was -81.20–121.61mm. There were 23 new concealed high risk points identified. The annual average deformation rate was -72.1574–51.6028mm/a, and the cumulative deformation variable was -165.6–112.4 mm. During the descending orbit, there were 21 obvious deformations and 16 newly discovered geological hazards. Taking a group of ascending orbit deformation zones in Yuanzhou District as an example, which proved that the application of SBAS-InSAR technology in the loess hilly area of Ningnan was feasible.
CFD analysis of wing-propeller interaction on the NASA X-57 Maxwell aircraft wing
Authors: Patil A. , Navrátil J.
Published: March 2024

Due to global warming concerns, the Aviation industry is trying to reduce its carbon footprint. Electric propulsion (EP) is one way of doing this, where the power is obtained from electrical sources. The concept of distributed electric propulsion (DEP) is in the focus now. NASA’s X-57 Maxwell, a high winged, all-electric experimental aircraft, uses this concept. The present work aims at developing a CFD model (ANSYS Fluent) to evaluate aerodynamic performance of two configurations of NASA’s X-57 aircraft wing; (i) wing and nacelle (clean wing) and (ii) wing, nacelle and one electric propeller under cruise condition; and compare it with the results of wind tunnel experiment performed by NASA/Armstrong X-57 research program. Parameters like lift, drag and pressure coefficients (CL, CD, CP) are compared for both cases. A good match is observed for CL, CD and CP, thus validating the model. The unsteady RANS solver is very efficient in capturing the effects of propeller slipstream on the wing. After validation, this model is further used to simulate aerodynamic performance of a wing with multi-propeller (DEP) configuration.
Prediction of environmental benefits introducing hybrid-electric propulsion on regional aircraft
Authors: Sirtori Gabriele , Trainelli Lorenzo , Riboldi Carlo E.D.
Published: March 2024

The objective of this paper is to assess the environmental benefits arising from the introduction of hybrid-electric propulsion on regional and commuter turboprop aircraft. A great focus is put on the propulsion based on a turbine engine coupled with batteries, combining mature technologies. The introduction of novel propulsion architectures on aircraft deployed on regional and commuter networks allows a substantial reduction of the fuel needed by airlines. In this work, scenarios based on real airline networks are presented, in order to quantify the reduction of greenhouse gas emissions possible considering the expected technological advancement for 2035 and 2050. This analysis is conducted by retrofitting the hybrid-electric propulsive system onto existing aircraft that can carry 19 passengers (Dornier DO228) or 70 passengers (ATR72-600). For the 19-seat class, a clean sheet design is also considered to overcome some limitations of the reference aircraft. A precise assessment of the peculiarities linked to the chosen propulsive configuration shows that networks that have shorter flights are better suited to the introduction of this technology, as the restriction on the design payload is less stringent. The proposed propulsive architecture allows a reduction of the operators’ yearly fuel budget of up to 50% in 2035 and 80% in 2050. At last, the taxi phase is of particular importance for regional aircraft that perform several rotations a day, therefore a further analysis of this phase is carried out. The result shows that the considered aircraft are capable of completing a full Landing & Take-Off (LTO) cycle without resorting to the thermal part of the propulsive system, reducing considerably the impact of the aircraft on the airport area.
Evolved version of Advanced Weather Awareness System in the COAST Project: latest developments and validation
Authors: Montesarchio M , Zollo A L , Ferrucci M , Bucchignani E
Published: March 2024

In the framework of the COAST (Cost Optimized Avionics SysTem) project, the Integrated Mission Management System (IMMS) has been developed, a technology aimed to automatically optimize the trajectory of Small Air Transport (SAT) vehicles considering, among possible obstacles, weather conditions, air-traffic and terrain. It is based on the interaction of the evolved versions of three systems, realized within COAST, including the Advanced Weather Awareness System (AWAS), devoted to provide on-board data regarding weather hazards monitored and forecast. The Evolved-AWAS technology has been developed by introducing several enhancements to its baseline version, in order to generate additional information required by IMMS for trajectory optimization. The current work describes the latest developments of Evolved-AWAS and the tests carried out to validate the prototype. All the new functionalities were tested verifying the correct generation of output data needed by IMMS and their visualization into the HMI (Human Machine Interface). The positive results of the performed tests ensured the proper functioning of the software, allowing its integration in the IMMS technology. Finally, the paper reports the outcomes of the last COAST flight demonstration campaign held in June 2023, which revealed the correct behaviour of the Evolved-AWAS, as well as of the overall IMMS.
Closed-loop control of a 3D printed soft actuator with integrated flex sensors and SMA wires
Authors: Wang Zhenbi , Acevedo-Velazquez Aline Iobana , Annadata Achyuth Ram , Winkler Anja , Röbenack Klaus , Modler Niels
Published: March 2024

This article presents a soft SMA-driven actuator capable of achieving desired bending angles. To create the actuator, flex sensors and Shape memory alloy (SMA) wires were embedded into the thermoplastic polyurethane (TPU) matrix of the sample during the 3D printing process. By deactivating and activating the two SMA wires according to sensing signals from the flex sensors, the actuator sample can track the input bending angle. This approach enabled closed-loop control and improved the overall efficiency of the system. Additionally, the proposed manufacturing process provides a simple and cost-effective solution for the rapid prototyping and custom design of smart materials with complex structures and high resolutions.
Preliminary Analysis and Optimization via CFD of a Liquid Hydrogen Pressure Regulating Piston Valve
Authors: Safaei Arash , Dalla Vedova Matteo D.L. , Maggiore Paolo
Published: March 2024

Due to their high reliability and precision, piston valves are frequently used for pressure regulating applications. Particularly in the aerospace industry, where cryogenic fluids such as liquid hydrogen are frequently used, the design and operation of piston valves become crucial. The current state of advancement of this technology in the cryogenic field is still in its early stages, owing to the difficulties in designing such complex systems in harsh environments. This justifies the need for further in-depth studies and analysis using CFDs tools and predictive models. In order to ensure an optimal and efficient use of a piston pressure regulating valve in cryogenic environment, it is necessary to understand the strengths and limitations of this technology in an extreme thermal and mechanical condition. The presented work concentrates therefore on a preliminary analysis and optimization of a piston valve operating in liquid hydrogen flow field, for pressure regulating applications. Particular focus will be dedicated to the overall dynamics of the main body of the piston, in terms of robustness and controllability of the desired response of the system. The dynamics of the piston within an extremely low-viscous flow, as well as the thermodynamic and fluid dynamic aspects of the valve system, will be discussed. Simulations of the flow field will be performed through CFD tool, crossing the results with the dynamics of the simulated system response through and implemented Simulink model. The obtained results will be then critically analysed in order to suggest possible optimization of the valve in the locations where the system is most affected from a thermal and mechanical standpoint.
Vee-Tail Preliminary Design Methodology for Class I mini- UAV
Authors: Nikolaou Eleftherios , Kostopoulos Vassilis
Published: March 2024

Unmanned Air Vehicles (UAVs) are becoming increasingly popular and widely used in a variety of industries. They can be used for tasks such as agriculture, construction, delivery, surveillance, rescue operations, mapping, wildlife tracking and many more. With the advancements in technology, UAVs are becoming more autonomous and able to perform tasks with minimal human intervention, so are widely used for military and law enforcement purposes. V-tail configurations are commonly used on UAVs due to their advantages in control and stability performance, as well as their ability to reduce drag and improve overall efficiency. However, research on V-tail design and sizing is limited, particularly for Class I mini-UAVs. The objective of this paper is to identify a methodology for a V-tail sizing of a Class I Mini UAV (NATO classification), which refers to the Conceptual and Preliminary Design of the UAV. The methodology will follow the design of a V-tail from the characteristics of the conventional tail of the UAV. Once the characteristics of the conventional tail were extracted, V-tail geometric characteristics (reference area, aspect ratio, mean aerodynamic chord, tail span, dihedral angle), were computed. Therefore, the aerodynamic characteristics of the V-tail have to be extracted, first as an isolated tail, and then as an installed tail. The stability derivatives of the V-tail are then calculated. The methodology for the analytical aerodynamic characteristics and stability derivatives, is a combination of NACA Report No.823 and Marcello R. Napolitano methodologies. Paul E. Purser and John P. Campbell provide design methods for V-tail on a NACA report, which include some of the desired stability derivatives. The rest of them will be calculated with Napolitano’s method. Marcello R. Napolitano gives a methodology for conventional tail sizing; thus, the equations of its methodology have to convert for a V-tail configuration. Furthermore, the aerodynamic characteristics and stability derivatives of the designed V-tail will be verified by Low Fidelity Aerodynamics simulation (XFLR5 software), and then by High Fidelity Aerodynamics by means of CFD. The results between low fidelity analytical values and High-Fidelity Aerodynamics values indicate a relative error lower than 20%.
L1
adaptive controller design for a tail fin controlled fixed wing unmanned aerial vehicle
Authors: Demirli Alican , Koç İlker Murat , Kürkçü Burak
Published: March 2024

The aim of this study is to design L1
adaptive controller, which is one of the robust control methods that can overcome model uncertainties, disturbances and noises, for a fixed-wing unmanned aerial vehicle (UAV) with tail fin controlled. In this context, first of all, the decoupled equations of motion of the six-degrees-of-freedom system are derived for the roll, pitch and yaw channels of the UAV. Then, the performance of the controller is demonstrated by simulation results for linearized system representation. By adding parameter errors to the system in question, the feature of tracking the given angle commands are analyzed. It has been observed that the L1
adaptive control structure exhibits rapid adaptation even in presence of system uncertainties. Finally, the controller is applied to the nonlinear system and operated throughout the entire flight envelope.
CFD aided investigation of a three-blade propeller in multirotor UAV applications
Authors: Vlachos S , Pliakos C , Bliamis C , Yakinthos K
Published: March 2024

In the recent years a rapid increase of multirotor UAVs in the commercial market is observed resulting in a large number of motor/propeller concepts and thrust architectures. The limited availability of data for the aerodynamic performance of the motor/propeller system often leads to a non-optimal operation on multirotor UAVs design points. Since experimental investigations are both cost- and time-demanding, the accurate CFD modeling of UAV propellers is crucial and highly supportive in the early design phases of multirotor UAVs. In the current study, a CFD framework is employed for the performance investigation of a small-scale three-blade propeller on a lightweight micro quadrotor UAV, designed for indoor search and rescue operations. More specifically, two widely implemented methods for propeller modeling are examined, namely the Multiple Reference Frame (MRF) and the Sliding Mesh (SM). Several operating points are investigated, corresponding to different propeller rotating speeds (RPM) and Reynolds numbers. The accuracy of each method is evaluated by comparing the CFD results with those obtained from literature experimental data. Finally, the uncertainty of the computational methods is quantified through Richardson’s extrapolation method.
Preliminary design of a multirotor UAV for indoor search and rescue applications
Authors: Pliakos C , Vlachos S. , Bliamis C , Yakinthos K
Published: March 2024

Multirotor UAVs have become an essential tool in a wider range of applications, including among others disaster management, and search and rescue (SAR) operations. Typically, these systems operate outdoors, with their guidance and positioning being based primarily on GPS. This work is focused on the design and optimization of a multirotor UAV specifically tailored for indoor SAR applications, where GPS signal is unavailable, and obstacles are prevalent. The design incorporates a lightweight frame structure, in order to increase the UAV’s payload capability. This is necessary, since the UAV requires multiple obstacle recognition and avoidance sensors, as well as thermal and optical cameras, to successfully accomplish its mission objectives in a GPS-denied environment. Towards this goal, various trade studies were conducted including different motor/propeller configurations and airframe FEM analyses. The aerodynamic performance of the UAV is evaluated also, using dedicated CFD analyses that incorporate the effect of propellers. Lastly, a prototype of the designed configuration is produced using additive manufacturing methods and initial flight tests of the UAV are performed.
Implementing and testing a U-space system: lessons learnt
Authors: Fas-Millán M-Á , Pick A , González del Río D , Paniagua Tineo A , García García R
Published: March 2024

Within the framework of the European Union’s Horizon 2020 research and innovation program, one of the main goals of the Labyrinth project, which ended on May 2023, was to develop and test the Conflict Management services of a U-space-based Unmanned Traffic Management (UTM) system. The U-space ConOps provides a high-level description of the architecture, requirements and functionalities of these systems, but the implementer has a certain degree of freedom in aspects like the techniques used or some policies and procedures. The current document describes some of those implementation decisions. The prototype included, at least in a basic version, part of the services defined by the ConOps, namely e-identification, Tracking, Geo-awareness, Drone Aeronautical Information Management, Geo-fence Provision, Operation Plan Preparation/Optimization, Operation Plan Processing, Strategic and Tactical Conflict Resolution, Emergency Management, Monitoring, Traffic Information and Legal Recording. Besides, a web app interface was developed for the operator/pilot. The system was tested in simulations and real visual line of sight (VLOS) and beyond VLOS (BVLOS) flights, with both vertical take-off and landing (VTOL) and fixed-wing platforms, while assisting final users interested in incorporating drones to support their daily tasks. The three-year experience developing and testing the environment provided many lessons at different levels: functionalities, compatibility, procedures, information, usability, ground control station (GCS) integration and aircrew roles during the mission.
An agent-based model for technology adoption in Air Traffic Management
Authors: Baena M , García-Cantú O , Mocholí D , Gil P , García A
Published: March 2024

Technology adoption depends not only on the development of new technologies, but also on the existence of regulations able to foster the implementation of such technologies. To facilitate the exploration of different policy options aimed at accelerating the adoption of new Air Traffic Management (ATM) technologies, an agent-based model that represents the behaviour of the European ATM system has been developed. This model includes representations of the main stakeholders in the ATM ecosystem: regulatory bodies, technology providers, labour unions and technology adopters, including Air Navigation Service Providers (ANSPs), airlines and airports. New ATM technologies, policies imposed, behavioural biases (e.g., loss aversion) and exogenous variables (e.g., fuel price) drive the actions of the agents, leading to the emergent global behaviour of the system. A calibration and validation process involving historical data, gaming experiments and participatory simulations was performed. The model was used to evaluate various policies that included economic incentives and penalties in two scenarios: one based on past events and another focused on the future. The results allow us to analyse which individual stakeholders benefit the most from each policy and to identify the mechanisms that emerge and drive the path of technology adoption, finding that a combination of economic incentives and penalties provides promising economical and operational results.
Radiation protection methods for suborbital aircrafts
Authors: Berti Q , Coutinho J , De Zotti L , Fanni A , Murrone M A
Published: March 2024

This paper presents the outcomes of a study conducted by SALTO team in the framework of the Student Aerospace Challenge, focusing on designing structures to optimize passenger protection against radiation in a suborbital vehicle. The study delves into space radiation characteristics and their potential impact on human health during suborbital flights. Through comprehensive research and the utilization of CARI-7A software, the team evaluated radiation exposure and explored both passive and active shielding solutions. The passive shielding solution involved the design of a multifunctional sandwich panel and a shielding layout for windows, minimizing weight penalties on the vehicle’s structure. Additionally, an active shielding concept utilizing high-temperature superconductor material and solenoid layouts was investigated. The study underscores the benefits and challenges associated with both passive and active shielding methods, emphasizing the importance of further exploration to enhance suborbital flight safety and pave the way for future human space exploration endeavors.
Experimental characterisation of a launcher’s fairing separation shock and its influence on RF antennas’ supporting structures
Authors: Fonseca Carmen , Alonso Daniel , Souza Alain
Published: March 2024

Fairing separation is a critical event during a rocket’s launch as it generates mechanical shocks that can cause partial or total onboard equipment failure. This study details the experimental results of the fairing separation shock of the launcher RFA ONE and its influence on the supporting structures of RF antennas. Accelerometers were used at multiple points of neighbouring structures to characterise the separation devices’ shock during fairing separation tests. Moreover, the shock propagation on different material structures, such as aluminium, carbon fibre, and Viton® elastomer sealant, was investigated. The results showed that the presence of Viton® sealant increased shock transmissibility. Further investigation was conducted to study the influence of applied torque on the separation locks on the shock levels. The study revealed that higher torques lead to increased magnitudes of shock acceleration. Finally, the paper provides recommendations for reducing the shock levels. The experimental results and recommendations presented in this paper provide valuable insights for launcher designers and manufacturers to ensure the safety and reliability of shock-sensitive components during flight.