bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous photon counting and charge integrating for pulse pile-up correction in paralyzable photon counting detectors
Authors: Treb Kevin , Radtke Jeff , Culberson Wesley S , Li Ke 
Published: June 2023

Abstract

Objective. In photon counting detectors (PCDs), electric pulses induced by two or more x-ray photons can pile up and result in count losses when their temporal separation is less than the detector dead time. The correction of pulse pile-up-induced count loss is particularly difficult for paralyzable PCDs since a given value of recorded counts can correspond to two different values of true photon interactions. In contrast, charge (energy) integrating detectors work by integrating collected electric charge induced by x-rays over time and do not suffer from pile-up losses. This work introduces an inexpensive readout circuit element to the circuits of PCDs to simultaneously collect time-integrated charge to correct pile-up-induced count losses. Approach. Prototype electronics were constructed to collect time-integrated charges simultaneously with photon counts. A splitter was used to feed the electric signal in parallel to both a digital counter and a charge integrator. After recording PCD counts and integrating collected charge, a lookup table can be generated to map raw counts in the total- and high-energy bins and total charge to estimate pile-up-free true counts. Proof-of-concept imaging experiments were performed with a CdTe-based PCD array to test this method. Main results. The proposed electronics successfully recorded photon counts and time-integrated charge simultaneously, and whereas photon counts exhibited paralyzable pulse pile-up, time-integrated charge using the same electric signal as the counts measurement was linear with x-ray flux. With the proposed correction, paralyzable PCD counts became linear with input flux for both total- and high-energy bins. At high flux levels, uncorrected post-log measurements of PMMA objects severely overestimated radiological path lengths for both energy bins. After the proposed correction, the non-monotonic measurements again became linear with flux and accurately represented the true radiological path lengths. No impact on the spatial resolution was observed after the proposed correction in images of a line-pair test pattern. Significance. Time-integrated charge can be used to correct for pulse pile-up in paralyzable PCDs where analytical solutions may be difficult to use, and integrated charge can be collected simultaneously with counts using inexpensive electronics.
Physics-informed neural networks for solving nonlinear Bloch equations in atomic magnetometry
Authors: Lei Gaoyi , Ma Ning , Sun Bowen , Mao Kun , Chen Baodong , Zhai Yueyang 
Published: June 2023

Abstract
In this study, we address the challenge of analyzing spatial spin distribution based on the nonlinear Bloch equations in atomic magnetometry through the use of physics-informed neural networks (PINNs). Atomic magnetometry plays a crucial role in the field of biomagnetism, where it is used to detect weak magnetic fields produced by the human brain, heart, and other organs. The Bloch equations describe the spin polarization of atomic clusters in an external magnetic field, but their nonlinearity can make the analysis of the spin distribution in spatial domain difficult. By utilizing PINNs, we provide a numerical solution to the nonlinear Bloch equations, examining the effect of different pump light schemes and wall collisions. Additionally, we propose a easily executed system identification method for the Bloch equations through the use of PINNs in a data-driven discovery mode, expanding the design space of atomic magnetometry beyond traditional simulation methods.
DRC-Net Method for Two-dimensional Spectral Classification
Authors: Zhang Ming-Ru , Gao Jun-Ping , Qiu Bo , Pu Yuan , Wang Xiao-Min , Li Rong , Fan Ya-Wen 
Published: June 2023

Abstract
Spectral classification plays a crucial role in the analysis of astronomical data. Currently, stellar spectral classification primarily relies on one-dimensional (1D) spectra and necessitates a sufficient signal-to-noise ratio (S/N). However, in cases where the S/N is low, obtaining valuable information becomes impractical. In this paper, we propose a novel model called DRC-Net (Double-branch celestial spectral classification network based on residual mechanisms) for stellar classification, which operates solely on two-dimensional (2D) spectra. The model consists of two branches that use 1D convolutions to reduce the dimensionality of the 2D spectral composed of both blue and red arms. In the following, the features extracted from both branches are fused, and the fused result undergoes further feature extraction before being fed into the classifier for final output generation. The data set is from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, comprising 15,680 spectra of F, G, and K types. The preprocessing process includes normalization and the early stopping mechanism. The experimental results demonstrate that the proposed DRC-Net achieved remarkable classification precision of 93.0%, 83.5%, and 86.9% for F, G, and K types, respectively, surpassing the performance of 1D spectral classification methods. Furthermore, different S/N intervals are tested to judge the classification ability of DRC-Net. The results reveal that DRC-Net, as a 2D spectral classification model, can deliver superior classification outcomes for the spectra with low S/Ns. These experimental findings not only validate the efficiency of DRC-Net but also confirm the enhanced noise resistance ability exhibited by 2D spectra.
Investigation of helium exhaust dynamics at the ASDEX Upgrade tokamak with full-tungsten wall
Authors: Zito A. , Wischmeier M. , Kappatou A. , Kallenbach A. , Sciortino F. , Rohde V. , Schmid K. , Hinson E.T. , Schmitz O. , Cavedon M. , McDermott R.M. , Dux R. , Griener M. , Stroth U. 
Published: June 2023

Abstract
An efficient removal of He ash by active pumping in future fusion devices is necessary to avoid fuel dilution and not degrade the core confinement properties. Therefore, a deep understanding of the underlying physics mechanisms is mandatory. Helium exhaust has been experimentally investigated at the ASDEX Upgrade tokamak. This is an ideal test environment, thanks to the ITER-like divertor geometry, an extensive diagnostics coverage and the presence of plasma-facing components made of tungsten. The exhaust efficiency, characterized by the He compression in the divertor, was found to improve with increasing divertor neutral pressure but to degrade with detachment. A multi-reservoir particle balance model was developed to interpret the observed exhaust dynamics, accounting for plasma transport and wall retention. The limited performance of the pumping system and the efficient helium retention capability of the tungsten wall were identified to have the strongest impact on the exhaust dynamics.
A rule-based energy management strategy for hybrid powered eVTOL
Authors: Marzougui Taher , Saenz Eduard Solano , Bareille Michel 
Published: June 2023

Abstract
In recent years, as the levels of air pollution reach alarming degrees, new energy aerial vehicles like electric Vertical Take-Off and Landing (eVTOL) aircraft have become the development trend of the future aviation industry. This paper presents a rule-based energy management strategy (EMS) for an eVTOL. The Hybrid Power System (HPS) is composed of Proton Exchange Membrane Fuel Cells (PEMFC) as the main energy source and Lithium-ion batteries (Li-ion) as auxiliary one. The onboard sources deliver power to the DC bus through two DC-DC converters. The main objective is to optimally split the power demand between the different sources while respecting their limits and extending their lifetimes. The adopted control strategy is based on State Machine Control (SMC). It is described as a set of rules based on some predefined conditions and thresholds over the control variables. It is chosen due to its simplicity of implementation, its reliability, and a low computation time. The relevance of this strategy is evaluated and implemented on a set of simulations for an eVTOL mission corresponding to a search and rescue flight. Results on power distribution, fuel cell dynamics, and battery parameters are analysed. They confirm the effectiveness of the proposed strategy.
Application of Model-Based Systems Engineering for the Integration of Electric Engines in Electrified Aircraft
Authors: Kiran Abhishek , Zaghari Bahareh , Kipouros Timoleon , Reis Ricardo Jose Nunes Dos 
Published: June 2023

Abstract
The objective of green, carbon-neutral flights is propelling the innovation of newer propulsion systems. With this increased development of an interdisciplinary form of propulsion for aircraft, the integration burdens and efforts intensify. In literature, it is estimated that it takes 10-15 years to design and develop an aircraft. The expected date of entry for any hybrid electric aircraft is 2035-2040. Any innovation and effort to cut this time by any degree should be explored and analysed. One of the techniques that have the potential to help fast-track the research and development of interdisciplinary systems is Model-based System Engineering (MBSE). Various studies have shown the benefit of employing a model-based design strategy. The focus case study relates to the integration of the electric machine and the propeller, along with related sub-systems. For Hybrid Electric Propulsion (HEP), the electric machine and propeller need to be integrated and their interaction to be analysed. MBSE is proposed as a methodology that would help streamline the process of design and integration of the two systems. This study documents the exploration of connecting MBSE with current simulation and modelling of sub-systems in order to ensure the fulfilment of stakeholder needs and full system effectiveness. This paper establishes the research problem, and the approach to be pursued, and gives notice of first developments and expected follow-up work.
Development, optimization, and testing of a hybrid solar panel concept with energy harvesting enhancement
Authors: Pattath Saseendran A , Hartl C , Tian Y , Qin Y 
Published: June 2023

Abstract
Photovoltaics (PV) is one of the important technologies for electricity generation from renewable energies today and has an excellent environmental sustainability. It is a fast-growing market worldwide and also offers opportunities for aviation to intensify the use of renewable sources. Although the efficiency of PV systems has increased to a certain extent in recent years, a predominant part of solar radiation acting on a PV system is still lost to the environment through reflection and convection as well as heat radiation from the heated PV system. In addition, the efficiency of these systems decreases with increasing heating. Possible solutions for energy harvesting of this energy loss through thermoelectric (TE) have been investigated theoretically and in part experimentally in various cases but have not yet been transferred to larger PV systems. At the same time, cooling the PV system through thermogenerators (TEG) allows its efficiency to be increased. This contribution presents first results from investigations into the design and testing of hybrid PV/TEG systems, which aim to increase the efficiency and improve economic manufacturability of such systems. Among others, important design aspects of hybrid PV/TEG systems and integration of IoT elements (Internet of Things) are addressed and the development of an analytical model to optimise hybrid systems is presented.
Mechanical behaviour for aeronautical structures with embedded electric cables under low energy impact
Authors: Vogel T , Walrick J-C , Casari P 
Published: June 2023

Abstract
The work focuses on the mechanical strength of composite structures with embedded electrical functionalities submitted to low energy impact. This material is defined for aeronautical applications as multilayers of glass fibre composite with flat electrical cable layers embedded. The main question is about the damage involved by the low energy impact, and its influence on the electrical cables layer performances. The impact leads to failure with no external signs of damage and insulation degradation. The dynamic experimental campaigns are carried out on drop tower tests with hemispherical tool. localized damage mechanisms at conductor interfaces are observed and a finite element model is performed. A link between impact energies and loss of electrical performance of multifunctional samples is established.
Description of the structure-property-function (SPF) relations of CNT-doped adhesive composites for the development of functional blocks
Authors: Tzortzinis Georgios , Madia Evgenia , Filippatos Angelos 
Published: June 2023

AbstractIn novel CNT-enhanced composite materials there has been noted a significant gap between material development and their application in engineering fields. In this context, we apply a function-integration design approach, where we propose a targeted material development and standardization through the adaption of functional blocks. Utilizing the structure-property-function (SPF) relations on the case study of CNT-doped adhesives, we map the internal structure of the system to targeted functions through selected properties. We highlight the influence of volume fraction and aspect ratio of CNTs on the homogenized properties of the composite and their extension on the targeted functions. We conclude that there exists a link between structure, property and function in a form which can be characterized as a functional block. Such approach can provide way to a standardized material selection, succeeding in a more function-oriented design of materials.
Gust and landing impacts as critical load cases for wings with distributed propulsion
Authors: Schubert Martin , Dafnis Athanasios , Schröder Kai-Uwe 
Published: June 2023

Abstract
The integration of distributed electric propulsion and energy storage systems into the wing structure significantly affects the mass distribution of the wing. Compared with conventional aircraft which are designed with engines mounted on the inner wing and integral fuel tanks, this substantially changes the overall loads on the wing structure. Assuming a retrofit scenario, this paper studies the influence of transient gust and landing impact loads on the dynamic behavior and the structural integrity of the wing of a representative conventional 19-seater commuter aircraft of CS-23 category retrofitted with distributed electric propulsion. Modal and dynamic response analyses are conducted based on a beam model idealizing the wing box of three wing designs: the reference wing with one main turboprop engine per half-wing, and two wings with integrated distributed electric propulsion. The results show for both load cases that the wing section loads obtained by dynamic response analysis exceed those predicted by equivalent quasi-static calculations. Compared with the reference wing, a significant increase of the amplitudes of the plunge and twist deformation and consequently higher section loads and stresses are observed for the retrofitted wing designs. It is concluded that both load cases are critical with regard to the structural integrity of the wing. However, the gust load case is more critical than the landing load case. These conclusions suggest that for the structural sizing of the wing, in particular for wings with distributed propulsion, and with regard to gust and landing impacts, the commonly applied quasi-static analyses should be accompanied by dynamic response analyses.
Preliminary tests on additive-manufactured Al-Sc specimens for the setup of a numerical model for Laser Shock Peening
Authors: Zavatta Nicola , Troiani Enrico 
Published: June 2023

Abstract
Aluminum-Scandium alloys offer a great potential in aerospace applications due their high corrosion resistance and improved strength properties. Furthermore, these alloys have been qualified for laser additive manufacturing (AM), producing parts with static strengths rivalling their conventionally manufactured counterparts. However, laser processing also results in large residual stresses that can severely affect fatigue properties and result in geometric distortion. A proven method for reducing the fatigue-related problems in metallic structures is to drive compressive residual stresses into the affected area by means of Laser Shock Peening (LSP). This surface treatment is very effective in bulk structures, improving life performances of fatigue-sensitive aeronautical components, such as jet engines turbine blades or helicopter gearboxes. On the other hand, quite a limited number of studies has been presented on the effect of LSP on fatigue crack growth in thin components and laser AM structures. This work presents first the results of preliminary tensile tests on additive manufactured Al-Sc specimens. The tensile strengths of as-built and heat-treated samples are compared. Then, a reliable and computationally time-effective numerical model of laser peening is reviewed, referring to case studies investigated earlier. In view of applying LSP to additive manufactured Al-Sc components, the effects of different laser parameters and geometries are discussed. Finally, the possible drawbacks of the LSP treatment are addressed, in order to exploit its full potential in increasing the fatigue life of AM components.
Performances of composites made from different recycled carbon fibre semi-products
Authors: Faure Alexandre , Mantaux Olivier , Gillet Arnaud 
Published: June 2023

Abstract
Recycled carbon fibres (rCF) were generally chosen for their low price and environmental features. However, performances of composites made of recycled carbon fibres are often too low to compete with lightweight alloys and glass fibre composites materials. As performances of rCF composites depend strongly on the fibres architecture, new semi-products with long and aligned recycled carbon fibres were developed by MANIFICA (Cleansky European Project). The use of long (up to 250mm) and highly aligned recycled fibres now provides rCF composites with excellent mechanical properties.
The purpose of this work is to assess the performances of composites manufactured with these new rCF semi-products. Semi-products with distinct architectures developed by MANIFICA are first presented. Then mechanical performances of composite plates manufactured from the different semi-products are evaluated. Results are finally compared in order to identify the effect of the manufacturing parameters of the semi-products on the final composite properties. This crucial information will allow end-users to select the right semi-product to design recycled carbon fibre composite innovative parts.
Chemical Recycling of Carbon Fibre Reinforced Polyurethane for Aviation Applications
Authors: Höhne Carl-Christoph , Brantsch Peter , Reichert Thomas , Hanich-Spahn Ronny 
Published: June 2023

Abstract
Carbon fibres are widely used in carbon fibre reinforced plastics (CFRP) for aviation, automotive, windmills, sport and many more application due to their outstanding material properties. Annually, this generates about 62,000 tonnes of end-of-life (EoL) CFRP and CFRP production waste. Current EoL scenarios for CFRPs show some disadvantages: Landfilling and incineration are not sustainable and environmentally friendly. Carbon fibre recovery by pyrolysis damages the carbon fibres and incinerates the plastic material. Mechanical recycling shortens the carbon fibres and is of limited value for thermosets. However, chemical recycling routes like solvolysis offers the great potential to recover damage-free carbon fibres as well as useful monomers for a new generation of plastics. Here we provide an overview about the solvolysis of carbon fibre reinforced polyurethane material for aviation applications. Additionally, first life cycle assessment results are presented.
Circularity studies on high performance thermoplastic demonstrators for the aircraft industry – End-of-Life concepts for PEKK/carbon fiber
Authors: Coskun S. , Prado L. A. S. A. , Das T. S. G. , Kötter A. , Sterk S. , Halm J. 
Published: June 2023

Abstract
In this study, the circularity of the different end-of-life concepts for PEKK reinforced with high performance carbon fiber composite parts were investigated. For this, two different thermoplastic demonstrators from Clean Sky 2’s ecoTECH Project were used. Recycling and circularity of the thermoplastic components were demonstrated by scraping the continues fiber reinforced thermoplastic fuselage panel parts into small flakes, which then were to be re-used as short fiber reinforced composite particles to produce compression molded Window Frames. For scraping, two different technologies were compared by means of quality, efficiency and environmental impacts. Based on different recycling and re-use options for both thermoplastic fuselage and Window Frame demonstrators, Linear Flow Index (LFI) and Material Circularity Indicator (MCI) parameters were calculated and used to showcase the alternative circularity levels of each scenario
Environmental Improvement Potential of Flexible Polyurethane Foam for Aviation Applications - A Case Example Analysis
Authors: Höhne Carl-Christoph , Salles Ana , Brantsch Peter , Reichert Thomas , Hanich-Spahn Ronny 
Published: June 2023

Abstract
The assessment of the environmental impacts of an aircraft and its components parts should go beyond the use phase when assessing its sustainability and circularity. Environmental impacts from the manufacturing phases e.g. related to consumption of resources, pollutions, and the use of hazardous materials as well as those from the end-of-life phase of an aircraft must not be neglected. Hence, a life cycle assessment (LCA) screening of the environmental impacts has been conducted based on a case example of polyurethane flexible foams (PUR-FF) for application on aircraft seating cushions. This analysis covers the production of PUR-FF with a particular focus on three perspectives: (i) production of bio-materials instead of fossil-based material; (ii) reduction and replacement of hazardous chemicals like heavy metal catalysts and flame retardants; and (iii) recovery of polyol by chemical solvolysis of PUR-FFs. The main results of the environmental improvement potentials of the PUR-FF are presented here.
Synthesis and characterization of bulk mechanical properties of a bio-based resin filled by graphene nanoplatelets and cellulose nanocrystals
Authors: Tserpes K , Lagkousi S , Tourountzi E , Floros G 
Published: June 2023

Abstract
In the present paper, a novel bio-based resin derived from epichlorohydrin was reinforced by Graphene NanoPlatelets (GNPs) and Cellulose NanoCrystals (CNCs) in different weight ratios and characterized experimentally through tension tests and fracture toughness tests on bulk specimens. The nanofillers were applied separately. The experimental results showed that the neat resin has a Young’s modulus of 3.29 GPa, a tensile strength of 45.15 MPa, a stress intensity factor of 0.61 MPa m1/2 and a critical strain energy release rate of 0.091 kJ/m2. The level of the properties reveal that the bio-based adhesive can be used for cosmetic and for some structural applications. The addition of cellulose nanocrystals in the epoxy resin didn’t improve the mechanical properties of the neat resin mainly due to the development of intense aggregation of cellulose nanocrystals. On the other hand, the addition of graphene has led to the increase of the Young’s modulus and the fracture toughness and to the decrease of the tension strength of the resin. Development of agglomerations of graphene were also present in this case. The contradictory findings on the mechanical properties of the reinforced resin gives a clear message about the need for optimizing the manufacturing process. Both nanocomposites have undergone a complete life-cycle analysis which has shown that they are far more environmentally friendly than a conventional epoxy resin.