bluuebunny/crossref_metadata_2025 huggingface dataset:
Individual-finger motor imagery classification: a data-driven approach with Shapley-informed augmentation
Authors: Alsuradi Haneen , Khattak Arshiya , Fakhry Ali , Eid Mohamad
Published: March 2024

Objective. Classifying motor imagery (MI) tasks that involve fine motor control of the individual five fingers presents unique challenges when utilizing electroencephalography (EEG) data. In this paper, we systematically assess the classification of MI functions for the individual five fingers using single-trial time-domain EEG signals. This assessment encompasses both within-subject and cross-subject scenarios, supported by data-driven analysis that provides statistical validation of the neural correlate that could potentially discriminate between the five fingers. Approach. We present Shapley-informed augmentation, an informed approach to enhance within-subject classification accuracy. This method is rooted in insights gained from our data-driven analysis, which revealed inconsistent temporal features encoding the five fingers MI across sessions of the same subject. To evaluate its impact, we compare within-subject classification performance both before and after implementing this augmentation technique. Main results. Both the data-driven approach and the model explainability analysis revealed that the parietal cortex contains neural information that helps discriminate the individual five fingers’ MI apart. Shapley-informed augmentation successfully improved classification accuracy in sessions severely affected by inconsistent temporal features. The accuracy for sessions impacted by inconsistency in their temporal features increased by an average of

26.3
%
±
6.70

, thereby enabling a broader range of subjects to benefit from brain–computer interaction (BCI) applications involving five-fingers MI classification. Conversely, non-impacted sessions experienced only a negligible average accuracy decrease of

2.01
±
5.44
%

. The average classification accuracy achieved is around 60.0% (within-session), 50.0% (within-subject) and 40.0% (leave-one-subject-out). Significance. This research offers data-driven evidence of neural correlates that could discriminate between the individual five fingers MI and introduces a novel Shapley-informed augmentation method to address temporal variability of features, ultimately contributing to the development of personalized systems.
Research on Clustering of Material Inspection Data for Highway Construction Projects Based on Agglomerative Hierarchical Clustering
Authors: Zhang Qun , Fang Shaohong , Ye Haolong
Published: March 2024

In large-scale highway construction projects, the project implementers will carry out detailed testing of various material indicators used in the project. By processing and analyzing these material testing data, we can reasonably classify large-scale highway construction projects, so that each project implementer can better manage the quality of the materials, which will greatly help all parties to strengthen the quality control of the project and improve the level of project management. This study first preprocesses the material testing data to obtain a structured data set suitable for data analysis. Then statistical features are constructed for the features in the dataset, including maximum, minimum, mean, median and standard deviation, to improve the performance and accuracy of the model. Next, the clustering hierarchical clustering method is applied for classification and the classification results are visualized in the form of dendrograms. Finally, through the comparison of performance analysis and clustering evaluation indexes, it is concluded that the classification of works into 3 or 4 categories according to material performance is in line with the actual level of engineering quality.
Enhancing Flame Retardancy and Thermal Insulation Performance of Silicone Rubber Composites Using Silicon Carbide
Authors: Lou Xu , Zang Chongguang , Pan Hongwei
Published: March 2024

This study focuses on modifying silicone rubber using silicon carbide (SiC) to enhance the flame retardancy and thermal insulation properties of the composites. The study characterizes the thermal stability, mechanical properties, and flame retardancy of the composite materials. The results demonstrate the effective improvement in thermal stability achieved by incorporating SiC into the silicone rubber composites. At a SiC addition level of 6 wt.%, the composite material shows optimal thermal stability with an initial decomposition temperature of 487°C, which is 84°C higher compared to the pure matrix. Additionally, the SiC/SR composites system exhibits a char yield of 72.13% at 900°C, representing an approximately 9% increase compared to the pure SR matrix. Simultaneously, the incorporation of SiC significantly enhances the flame retardancy of silicone rubber. At a SiC addition level of 10 wt.%, the LOI (Limiting Oxygen Index) value increases by 10.5% to reach 30.4%, surpassing the non-additive sample. Moreover, the UL-94 classification of the composite material is V-0, meeting the standard for flame retardant materials.
Effect of Graphene Particle Diameter on Mechanical Properties of Graphene Composite Material
Authors: Ni Guanyun
Published: March 2024

In order to improve the mechanical properties of alloys and broaden their application fields, high-performance metal matric composites have received more and more attention. Graphene has excellent mechanical properties and is often used as a reinforcing phase for various composite materials. However, as the reinforcing phase of the composite, the number, shape, and size of graphene have a significant effect on the overall mechanical properties of the composites. Therefore, the influence of graphene particle diameter on the mechanical properties of graphene particle reinforced metal matrix composites was studied in this paper. By establishing a series of finite element models, we simulated the mechanical behaviour of composite materials under static tension loading. The relationship between graphene particle diameter and material mechanical properties is revealed.
Effect of La2O3 adding on Properties of SiC Porous Ceramic Support
Authors: Qiu Shuang , Xue RiDong , Dai Xinchao , Wu Chengjun , Deng Xiangyun
Published: March 2024

In this paper, 80-90 grains of SiC as the main raw material, doped La2O3 into the binder composed of potassium feldspar, kaolinite and quartz, and then graphite and activated carbon as pore-making agents to prepare silicon carbide porous ceramic carrier. The effects of doped La2O3 content on the bending strength, porosity and filtration pressure drop of porous SiC ceramics were studied. The results show that the formation of mullite phase and the bending strength of SiC porous ceramics can be improved by adding proper amount of La2O3. Under the sintering temperature of 1300°C for 90 minutes, when the content of La2O3 in the binder is 2.5wt%, the comprehensive performance is the best, the porosity is 21.5%, the bending strength is 53.5MPa, and the filtration pressure drop is low.
Overview of safety challenges associated with integration of hydrogen-based propulsion systems for climate neutral aviation
Authors: Dimos Dimitrios , Graaf Stefanie de
Published: March 2024

Electrification through hydrogen-based fuel cells as well as hydrogen combustion in gas turbines is a key strategy in aviation for achieving substantial reduction of emissions. However, this transition presents multifaceted challenges. Besides the development and improvement of technologies required for such hydrogen-fuelled aero engines, the safety of hydrogen storage and distribution systems on aircraft is paramount. Challenges associated with hydrogen in terms of its material properties, the design and selection of components for the conditioning and distribution, as well as the system design are being presented and discussed in this work. This includes the consideration of high diffusivity, flammability and reactivity of hydrogen and the consequences of these traits: hydrogen embrittlement, hydrogen-induced cracking and leakage, for instance. The challenges elaborated in this work are pertinent to both hydrogen fuel cell-based propulsion systems and hydrogen combusting gas turbines. Design considerations were derived and are being outlined in this work. These are transferable to applications in other industries such as automotive and stationary power plants. The need for novel rigorous safety protocols to enable a sustainable future in aviation is being highlighted.
H2Electra – a platform for comparative analysis of integration concepts for hydrogen-based electric propulsion in regional aircraft
Authors: Graaf Stefanie de , Bahrs Victor , Tarbah Noah , Kazula Stefan
Published: March 2024

Over the past decade numerous novel concepts for electric flight have been elaborated. Each unique in its own way and based on various assumptions and technological advances projected for the future. Within each concept design decisions have to be made on component level, propulsion system level and aircraft level. In order to be able to evaluate and analyse both, advanced components technologies and innovative propulsion system architectures, as well as to understand the effect of each design decision, a common baseline platform has been developed to allow for comparative analyses.

This work presents such a platform with the hydrogen-based electrified regional aircraft concept called H2Electra. The iterative design process developed for this purpose is presented. It allows for a holistic approach to the development of an aircraft, its electrified propulsion system as well as the sizing of the components therein. Two propulsion system integration concepts are being considered in the evaluation: one partially fuselage-integrated and one nacelle-integrated. Challenges and trade-offs between the two concepts were analysed and evaluated, with safety and reliability being key design and decision-making metrics, alongside block-fuel efficiency and power density. In particular, the design decision on a suitable bus voltage and its effect on the powertrain sizing and integration were investigated.
Gappy POD model for Structural Compliance of the Wing of a Civil Tilt-rotor
Authors: Amendola Gianluca , Cinquegrana Davide , Quagliarella Domenico , Belardo Marika , Chiariello Antonio
Published: March 2024

The selection of the most critical load conditions is an extremely important topic as it allows the design and structural verification to be limited to a limited subset of conditions that envelop the operational thousands of the Design Limit Load (DLL) book without necessarily having to apply a direct approach. Often, thousands of analyses are performed by a Detailed Finite Element Model (DFEM, including model loading, post-processing and full stress and buckling analysis) taking a long time with a higher probability of error. This work describes the effort to set up a surrogate model of a composite wing, which aims to supply, accurately and efficiently, the structural response of the wing to several solicitation loads that populate the DLL. The surrogate model is defined by employing the Proper Orthogonal Decomposition technique (POD), trained on partial knowledge of data. The snapshots collected are composed of load solicitations and, limited to a subset of wing elements, stress and strain states resulting from the structural response to the relative load solicitation in a numerical analysis. Gappy-POD algorithm is set up to deal with this lack of data in the querying stage when only the solicitations are known. The surrogate model training starts with a selection of loads from the DLL, while its reliability is increased by iteratively adding further FEM analyses based on error maps opportunely defined.
Structural Analysis of a Large-scale Model for the Wind Tunnel Test of a Multiadaptive Flap
Authors: Sіcіm Demіrcі Mürüvvet Sinem , Pecora Rosario , Orhan Kaya Metin
Published: March 2024

Innovative studies on morphing wing structures with the highest potential to improve aerodynamic performance on large aircraft are running under the CleanSky2 platform to validate the morphing architectures on true-scale demonstrator through ground and wind tunnel tests. Research activities have been conducted to develop a revolutionary multi-modal camber morphing flap to enhance the aerodynamic behaviour of a new generation of regional aircraft within this challenging framework. The design and validation of the intelligent architecture capable of different morphing modes required for low-speed (take-off/landing) and high-speed (cruise)conditions. To enhance the significance and applicability of the wind tunnel test campaign, a significant scale factor of 1:3 was selected for the test article. In this study, general layout of the mechanical model and FE analysis performed both inner and outer flap will be presented. A comprehensive structural analysis of the flap test article was conducted to ensure the safety and effectiveness of the conceived mechanical solutions. Linear static analyses were performed using the finite element (FE) method within the Ansys Workbench® environment. These analyses aimed to assess the adequacy of the mechanical solutions and validate the test article’s structural integrity.
Rapid, iterative design approach for preliminary configuration of a High Altitude, Long Endurance aircraft
Authors: Deuschle Lukas , Kirchner Edgar , Obert Lara , Aust Erwin , Stoll Luca , Marr Niels , Grieb Prof. Dr.- Ing. Markus
Published: March 2024

This paper presents a rapid iterative design approach, used to develop a preliminary configuration of an Unmanned Aerial Vehicle (UAV), which is to perform a High-Altitude, Long Endurance (HALE) mission. First, based on a set of requirements, an initial aircraft concept is developed.

The rapid iterative design approach revolves around an energy-based flight profile simulation, which is updated with an improved aerodynamic model of the aircraft during every iteration. An aircraft configuration is defined by a set of constant parameters. A corresponding flight profile consists of an altitude and velocity profile, as a function of time. The behaviour of the aircraft is simulated based on the specified flight profile.

For sizing the aircraft components exposed to the airstream, the aerodynamic design phase aims to create an airframe which achieves the performance outlined in the flight performance simulation, utilizing the obtained aircraft parameters. Using the geometric data, a 3D-model of the aircraft is created, which is essential for the aircraft’s weight and balance calculations and for determining the airframe shape exposed to the airflow. A Computational Fluid Dynamics (CFD) simulation is conducted to obtain the actual aerodynamic characteristics of the airframe. If the performance requirement of the flight performance simulation is not met, another iteration of the aerodynamic design phase is required.

The design framework stands out due to its rapid iteration capability, accessibility, and straightforward application, making it particularly advantageous for educational settings in which students engage with aircraft design. The approach aims to offer satisfactory results for an initial aircraft conceptualization.

This design framework emerged from the DLR Design Challenge 2023, an annual competition hosted by the German Center for Aerospace Research, where student teams develop preliminary aircraft designs. This years challenge tasked the teams with designing an aircraft system to restore internet coverage over a disaster-affected region. The described approach was used to develop the Sentinel System of the DHBW Ravensburg team. However, the simulation and development process is not limited to applications within this challenge.
An event-driven link-level simulator for validation of AFDX and Ethernet avionics networks
Authors: Vera-Soto Pablo , Villegas Javier , Fortes Sergio , Pulido José , Escaño Vicente , Ortiz Rafael , Barco Raquel
Published: March 2024

Aircraft are composed of many electronic systems: sensors, displays, navigation equipment and communication elements. These elements require a reliable interconnection, which is a major challenge for communication networks as high reliability and predictability requirements must be verified for safe operation. In addition, their verification via hardware deployments is limited because these are costly and make difficult to try different architectures and configurations, thus delaying the design and development in this area. Therefore, verification at early stages of the design process is of great importance that has to be supported via simulation. In this context, the present work presents an event-driven link level framework and simulator for the validation of avionics networks. The presented tool supports communication protocols such as Avionics Full-Duplex Switched Ethernet (AFDX), which is a common protocol in avionics, as well as Ethernet, which is used with static routing in such scenarios. The simulator also uses realistic element models to provide accurate results. The proposed platform is evaluated in Clean Sky’s Disruptive Cockpit for Large Passenger Aircraft architecture scenario. The speed of the verification is a key factor, so the computational cost is analyzed, proving that the execution time is linearly dependent on the number of messages sent.
Simulation of an Aerospace Electrohydraulic Servomechanism, with different Coulomb Friction models
Authors: Alimhillaj P , Lamani L , Dalla Vedova M D L
Published: March 2024

The contemporary design of flight control systems demands the utilization of intricate models for the in-depth analysis of individual components or subsystems. Conversely, there is a parallel need for more foundational and synthetic models that offer sufficient accuracy, specifically tailored for preliminary design, monitoring, or diagnostic purposes.

This paper centers on electro-hydraulic servomechanisms designed for aeronautical applications, emphasizing their contemporary significance. These systems play a crucial role, particularly in primary flight commands characterized by precise position servo control.

The great variety of configurations and applications, their complexity and the criticality that characterizes this servomechanisms, deemed appropriate to devote particular attention to their modeling and the development of numerical simulation systems models that are versatile and reliable (flexible and easily applicable to different real systems but capable of providing realistic simulations). In particular, in this work are presented two innovative Coulomb friction models which are applied through MATLAB/Simulink block diagram structure to the model of the electrohydraulic servomechanism. The two friction models are foreseen to overcome the problematic of standard models for the friction, giving more realistic results, increasing the accuracy of the simulations.
Investigation of noise reduction effects of individual and combined geometrical modifications on UAM propeller blades
Authors: Skrna D , de Rosa Jacinto da Silva M , Berens M
Published: March 2024

The development of a future transportation concept in cities may also include transportation of passenger and cargo at various altitudes in order to reduce the load on the ground infrastructure. This is known as urban air mobility (UAM), facilitated by the application of electrical vertical take-off and landing (eVTOL) vehicles. Public acceptance is required with regard to safety aspects in densely populated areas, but also in terms of noise emissions. As with almost any aircraft, the propulsion systems, in most cases the propeller blades, are the main source of noise generation. In literature, experimental and numerical results for geometric blade modifications for the purpose of noise reduction are provided only for small diameter propellers. This paper investigates the individual features at larger diameter propellers by means of numeric aeroacoustic simulations with OpenFOAM. The modifications include serrations of the trailing edge, leading edge tubercles and blade tip adaptations. Moreover, the combination of those features is investigated in a parameter study for various rotational velocities and several flight modes. The key effect, namely a reduction of broadband noise, can be observed for several cases, but the strength of it varies. An optimization process is necessary to obtain an efficient noise reduction for all operating conditions of a particular aircraft design.
Experimental investigation of blade-shaped riblets for drag reduction on UAV applications
Authors: Bliamis C , Panagiotou P , Vlahostergios Z , Misirlis D , Yakinthos K
Published: March 2024

This study presents an experimental investigation of blade-shaped riblets for drag reduction in unmanned aerial vehicle (UAV) applications. UAVs have gained significant attention since they can perform various missions, including surveillance, reconnaissance, and package delivery. However, their aerodynamic performance, specifically the high drag associated with their exposed surfaces, remains a key challenge for enhancing their efficiency and extending their flight endurance. To address this issue, riblet geometries are proposed as a potential solution, which can reduce the turbulent skin friction drag by up to 8%. The experimental investigation involves wind tunnel testing of blade-shaped riblets, with various spacing-to-height (s/h) ratios and constant groove cross-sectional area (Ag). The riblets are designed for application on the wing, empennage, and fuselage surfaces of a UAV. The investigations are performed on a flat plate for various flow conditions, including different freestream velocities, to evaluate the drag reduction effectiveness of the riblet configuration. The drag force is measured using a force balance system and flow visualization techniques are employed to assess the position where the boundary layer has transitioned to fully turbulent. The results demonstrate the drag-reducing effect of blade-shaped and trapezoidal riblets and the different performances observed for the various s/h ratios. The cases with s/h=1 result in the smallest drag coefficients, while the cases with s/h=2 have significantly increased drag values, compared to the smooth flat plate, due to the increased wetted surface area. These findings highlight the potential of riblets as an effective drag-reduction technique for UAV applications, enabling increased endurance and/or enhanced payload capacity.
Enabling Human-Autonomy Teaming in Aviation: A Framework to Address Human Factors in Digital Assistants Design
Authors: Bjurling O , Müller H , Burgén J , Bouvet C J , Berberian B
Published: March 2024

The introduction of artificial intelligence (AI) tools in aviation necessitates more research into human-autonomy teaming in these domain settings. This paper describes the development of a design framework for supporting Human Factors novices in considering human factors, improving human-autonomy collaboration, and maintaining safety when developing AI tools for aviation settings. Combining elements of Hierarchical Task Analysis, Coactive Design, and Types and Levels of Autonomy, the design framework provides guidance in three phases: modelling and understanding the existing system and associated tasks; producing a new function allocation for optimal Human-Autonomy Teaming (HAT); and assessing HAT-related risks of the proposed design. In this framework, designers generate a comprehensive set of design considerations to support subsequent development processes. Framework limitations and future research avenues are discussed.
Air Travel Itinerary Market Share Prediction using Artificial Intelligence
Authors: Serrano-Ortega A , Cano-González Á , Toledo-Garrote A , Chamoso P
Published: March 2024

The widely used Quality Service Index (QSI) model estimates air traffic by considering attributes such as capacity, connectivity, and travel time, which impact an itinerary market share (MS) in the origin-destination (OD) market. To determine itinerary attractiveness, the conventional QSI model combines these features, weighting them based on their significance and generates a score for each option. The key is therefore to select the optimal combination of weighted attributes that are able to forecast the MS with the desired accuracy. However, traditional QSI models rely on expert knowledge and assume that the traffic generation and allocation is always based in the same market principles, hindering their ability to generalize and identify new features. To address this, the present work, which is part of a research project entitled ERA funded by Red.es, introduces a generalized rationale based on Artificial intelligence using historical data, a challenge that has been faced in the early stages of the project. This approach enables the identification and understanding of key features in the aviation traffic and the development of a forecasting model capable of capturing more complex feature relationships.
Analysis of Film Cooling for a 3kN LOX/butane Demonstrator Engine
Authors: Ashford Z A R
Published: March 2024

Regenerative cooling has been the primary cooling method for every modern launch vehicle engine, except for the Viking: a film-cooled (with ablative throat) N2O4 / UH25 engine used on the first stage of the Ariane rockets 2-4. Despite this, film-cooling as a stand-alone cooling method has traditionally been considered insufficient for the high combustion temperatures and long burn times associated with launcher engines. This study explored the feasibility of a solely film-cooled engine at the demonstrator scale (3 kN), as a prototype for a lightweight launcher engine. A wide range of liquid oxygen (LOX)/butane engines were modelled and from this a relationship was determined to predict chamber wall temperature for a given oxidiser-to-fuel ratio (O/F), chamber pressure, and amount of film cooling. Notably, this equation was found to apply to both a 3 kN and a 30 kN engine. Numerical modelling of engine specific impulse (Isp) using this equation then found the conditions yielding optimal engine performance.
Qualification test campaign of RFA one fairing engineering model
Authors: Meireles P , Hooton J , Colaço L , Alonso D , Pinheiro L
Published: March 2024

The fairing is an important element of the rocket as it protects the payload from the external environment during the most aggressive phases of the flight. A test campaign was developed with the aim of qualifying the fairing structure of the RFA One. This test is intended to simulate the quasi-static loads of the most critical phase during flight. A FEA model was developed to identify the most critical phase of flight and to identify the quasi-static reactions that replicate the flight loads. Based on these reactions, the loads and test levels were defined. The test results were compared with the FEA data to correlate and improve the model. The static test was successfully performed at acceptance and qualification Level 2. The load and strain results indicate that the DLL was achieved and exceeded by a factor of 1.11, while the fairing maintained its functionality and key performance. This paper presents the most relevant results of the test, discusses the results compared with the FEA model and summarizes some lessons drawn from the test campaign.
Influences of temperature on the property of ITO/Teflon/Ag in atomic oxygen environment
Authors: Guo Liang , Qiu Tiecheng , Zhang Qian , Guo Zhanping , Shan Ming
Published: March 2024

This paper uses ground simulation equipment for an atomic oxygen environment to conduct experimental research on ITO/Teflon/Ag, which is used in spacecraft using an atomic oxygen environment. The atomic oxygen integrated flux selected in the study is 9.1× 1019 atoms/cm2, with a vacuum degree of 10-2 Pa, and sample temperatures of 20°C, 70°C, and 120°C, respectively, were selected to investigate the possible impact of sample temperature on atomic oxygen environment simulation experiments. After the test, a high-precision microelectronic balance was used to test the mass loss of the sample and calculate the reaction rate of the material. The thermal emissivity and solar absorption ratio of the sample were tested using TEMP 2000A and LPSR 300, respectively. Through experiments and analysis, it was found that as the sample temperature increased, the ITO/Teflon/Ag reaction rate with atomic oxygen gradually increased but remained at 10-25. Atomic oxygen and temperature have a significant impact on the thermal physical properties of the material.
Research on the performance of pavement crack repair materials based on foaming polyurethane
Authors: Zhou You , Chen Fei , Xu Zhoucong
Published: March 2024

In this paper, Pucs, a new two-component foaming polyurethane material, is selected to carry out a feasibility study on its application in pavement crack repair. Based on the two common crack repair materials in current projects, tests of pavement performance of repair materials are carried out, such as bonding performance, water damage resistance performance, high-temperature performance, and aging resistance performance. The comparative analysis of the results reveals that Pucs have better pavement performance than conventional crack repair materials. This indicates that Pucs is a new kind of material with excellent performance in pavement crack repair and can be widely used in the field of crack repair.
Characteristics of bioplastics prepared from cassava starch reinforced with banana bunch cellulose at various concentrations
Authors: Saputri C A , Julyatmojo F A , Harmiansyah  , Febrina M , Mahardika M , Maulana S
Published: March 2024

Human activities have led to the pollution of the environment through the accumulation of plastic waste. Since plastics are resistant to decomposition resulting negative impact on the environment, there is a pressing need for the development of bioplastics. Starch is a such of natural material that can be used made of bioplastics. However, bioplastics from starch were needed to improve starch-based bioplastics due to their brittle properties. To address this issue, researchers focused on enhancing starch-based bioplastics by incorporating cellulose, particularly derived from kepok banana bunch fibers and cassava starch variety UJ3. The production process involved adding varying concentrations of 2.5, 5, 7.5, and 10 % (wt) of kepok banana bunch cellulose. The findings indicated that increasing cellulose concentration improved the characteristics of the bioplastic materials significantly. The results showed that the addition of cellulose concentration improved the mechanical properties, water vapor absorption, and biodegradability of bioplastics. With an optimal cellulose concentration level at 7.5%, remarkable enhancements in tensile strength (from 2.92 to 6.72 MPa), reduced elongation percentage (from 20.89 to 4.06%), increased Young’s Modulus values (from 13.98 to 172.52 MPa), decreased water vapor absorption rate (from 15,93 to 11,48%), and enhanced bio-degradability rating (from 29,81 to 50,69%) were observed.
CM points, class numbers, and the Mahler measures of 𝑥³+𝑦³+1-𝑘𝑥𝑦
Authors: Tao Zhengyu , Guo Xuejun
Published: March 2024

We study the Mahler measures of the polynomial family

Q
k

(
x
,
y
)
=

x
3

+

y
3

+
1
−
k
x
y

Q_k(x,y) = x^3+y^3+1-kxy

using the method previously developed by the authors. An algorithm is implemented to search for complex multiplication points with class numbers

⩽
3

\leqslant 3

, we employ these points to derive interesting formulas that link the Mahler measures of

Q
k

(
x
,
y
)

Q_k(x,y)

to

L
L

-values of modular forms. As by-products, some conjectural identities of Samart are confirmed, one of them involves the modified Mahler measure

n
~

(
k
)

\tilde {n}(k)

introduced by Samart recently. For

k
=

729
±
405

3

3

k=\sqrt [3]{729\pm 405\sqrt {3}}

, we also prove an equality that expresses a

2
×
2

2\times 2

determinant with entries the Mahler measures of

Q
k

(
x
,
y
)

Q_k(x,y)

as some multiple of the

L
L

-value of two isogenous elliptic curves over

Q

(

3

)

\mathbb {Q}(\sqrt {3})

.
On discrete ground states of rotating Bose–Einstein condensates
Authors: Henning Patrick , Yadav Mahima
Published: March 2024

The ground states of Bose–Einstein condensates in a rotating frame can be described as constrained minimizers of the Gross–Pitaevskii energy functional with an angular momentum term. In this paper we consider the corresponding discrete minimization problem in Lagrange finite element spaces of arbitrary polynomial order and we investigate the approximation properties of discrete ground states. In particular, we prove a priori error estimates of optimal order in the

L
2

L^2

- and

H
1

H^1

-norm, as well as for the ground state energy and the corresponding chemical potential. A central issue in the analysis of the problem is the missing uniqueness of ground states, which is mainly caused by the invariance of the energy functional under complex phase shifts. Our error analysis is therefore based on an Euler–Lagrange functional that we restrict to certain tangent spaces in which we have local uniqueness of ground states. This gives rise to an error decomposition that is ultimately used to derive the desired a priori error estimates. We also present numerical experiments to illustrate various aspects of the problem structure.
GMRES, pseudospectra, and Crouzeix’s conjecture for shifted and scaled Ginibre matrices
Authors: Chen Tyler , Greenbaum Anne , Trogdon Thomas
Published: March 2024

We study the GMRES algorithm applied to linear systems of equations involving a scaled and shifted

N
×
N

N\times N

matrix whose entries are independent complex Gaussians. When the right-hand side of this linear system is independent of this random matrix, the

N
→
∞

N\to \infty

behavior of the GMRES residual error can be determined exactly. To handle cases where the right hand side depends on the random matrix, we study the pseudospectra and numerical range of Ginibre matrices and prove a restricted version of Crouzeix’s conjecture.
Large-scale Monte Carlo simulations for zeros in character tables of symmetric groups
Authors: Miller Alexander , Scheinerman Danny
Published: March 2024

This is a brief report on some recent large-scale Monte Carlo simulations for approximating the density of zeros in character tables of large symmetric groups. Previous computations suggested that a large fraction of zeros cannot be explained by classical vanishing results. Our computations eclipse previous ones and suggest that the opposite is true. In fact, we find empirically that almost all of the zeros are of a single classical type.
Tensor products and solutions to two homological conjectures for Ulrich modules
Authors: Miranda-Neto Cleto , Souza Thyago
Published: March 2024

We address the problem of when the tensor product of two finitely generated modules over a Cohen-Macaulay local ring is Ulrich in the generalized sense of Goto et al., and in particular in the original sense from the 80’s. As applications, besides freeness criteria for modules, characterizations of complete intersections, and an Ulrich-based approach to the long-standing Berger’s conjecture, we give simple proofs that two celebrated homological conjectures, namely the Huneke-Wiegand and the Auslander-Reiten problems, are true for the class of Ulrich modules.
Patterns of structural reflection in the large-cardinal hierarchy
Authors: Bagaria Joan , Lücke Philipp
Published: March 2024

We unveil new patterns of Structural Reflection in the large-cardinal hierarchy below the first measurable cardinal. Namely, we give two different characterizations of strongly unfoldable and subtle cardinals in terms of a weak form of the principle of Structural Reflection, and also in terms of weak product structural reflection. Our analysis prompts the introduction of the new notion of

C

(
n
)

C^{(n)}

-strongly unfoldable cardinal for every natural number

n
n

, and we show that these cardinals form a natural hierarchy between strong unfoldable and subtle cardinals analogous to the known hierarchies of

C

(
n
)

C^{(n)}

-extendible and

Σ
n

\Sigma _n

-strong cardinals. These results show that the relatively low region of the large-cardinal hierarchy comprised between the first strongly unfoldable and the first subtle cardinals is completely analogous to the much higher region between the first strong and the first Woodin cardinals, and also to the much further upper region of the hierarchy ranging between the first supercompact and the first Vopěnka cardinals.
Slicing knots in definite 4-manifolds
Authors: Kjuchukova Alexandra , Miller Allison , Ray Arunima , Sakallı Sümeyra
Published: March 2024

We study the

C
P

2

\mathbb {CP}^2

-slicing number of knots, i.e. the smallest

m
≥
0

m\geq 0

such that a knot

K
⊆

S
3

K\subseteq S^3

bounds a properly embedded, null-homologous disk in a punctured connected sum 

(

#
m

C
P

2

)

×

(\#^m\mathbb {CP}^2)^{\times }

. We find knots for which the smooth and topological

C
P

2

\mathbb {CP}^2

-slicing numbers are both finite, nonzero, and distinct. To do this, we give a lower bound on the smooth

C
P

2

\mathbb {CP}^2

-slicing number of a knot in terms of its double branched cover and an upper bound on the topological

C
P

2

\mathbb {CP}^2

-slicing number in terms of the Seifert form.
Regularity of capillarity droplets with obstacle
Authors: De Philippis Guido , Fusco Nicola , Morini Massimiliano
Published: March 2024

In this paper we study the regularity properties of

Λ
\Lambda

-minimizers of the capillarity energy in a half space with the wet part constrained to be confined inside a given planar region. Applications to a model for nanowire growth are also provided.
Bounded differentials on the unit disk and the associated geometry
Authors: Dai Song , Li Qiongling
Published: March 2024

For a harmonic diffeomorphism between the Poincaré disks, Wan [J. Differential Geom. 35 (1992), pp. 643–657] showed the equivalence between the boundedness of the Hopf differential and the quasi-conformality. In this paper, we will generalize this result from quadratic differentials to

r
r

-differentials. We study the relationship between bounded holomorphic

r
r

-differentials/

(
r
−
1
)

(r-1)

-differential and the induced curvature of the associated harmonic maps from the unit disk to the symmetric space

S
L
(
r
,

R

)

/

S
O
(
r
)

SL(r,\mathbb R)/SO(r)

arising from cyclic/subcyclic Higgs bundles. Also, we show the equivalence between the boundedness of holomorphic differentials and having a negative upper bound of the induced curvature on hyperbolic affine spheres in

R

3

\mathbb {R}^3

, maximal surfaces in

H

2
,
n

\mathbb {H}^{2,n}

and

J
J

-holomorphic curves in

H

4
,
2

\mathbb {H}^{4,2}

. Benoist-Hulin and Labourie-Toulisse have previously obtained some of these equivalences using different methods.
Long time dynamics of nonequilibrium electroconvection
Authors: Lee Fizay-Noah
Published: March 2024

The Nernst-Planck-Stokes (NPS) system models electroconvection of ions in a fluid. We consider the system, for two oppositely charged ionic species, on three dimensional bounded domains with Dirichlet boundary conditions for the ionic concentrations (modelling ion selectivity), Dirichlet boundary conditions for the electrical potential (modelling an applied potential), and no-slip boundary conditions for the fluid velocity. In this paper, we obtain quantitative bounds on solutions of the NPS system in the long time limit, which we use to prove (1) the existence of a compact global attractor with finite fractal (box-counting) dimension and (2) space-time averaged electroneutrality

ρ
≈
0

\rho \approx 0

in the singular limit of Debye length going to zero,

ϵ
→
0

\epsilon \to 0

.
Aortic Calcification is Associated With the Difference Between Invasive Central and Cuff-Measured Brachial Blood Pressure in Chronic Kidney Disease
Authors: Nyvad Jakob , Christensen Kent Lodberg , Andersen Gratien , Reinhard Mark , Maeng Michael , Nielsen Sebastian , Thomsen Martin Bjergskov , Jensen Jesper Møller , Nørgaard Bjarne Linde , Buus Niels Henrik
Published: March 2024

BACKGROUND

Chronic kidney disease (CKD) is associated with accelerated vascular calcification and increased central systolic blood pressure when measured invasively (invCSBP) relative to cuff-based brachial systolic blood pressure (cuffSBP). The contribution of aortic wall calcification to this phenomenon has not been clarified. We, therefore, examined the effects of aortic calcification on cuffSBP and invCSBP in a cohort of patients representing all stages of CKD.

METHODS

During elective coronary angiography, invCSBP was measured in the ascending aorta with a fluid-filled catheter with simultaneous recording of cuffSBP using an oscillometric device. Furthermore, participants underwent a non-contrast computed tomography scan of the entire aorta with observer-blinded calcification scoring of the aortic wall ad modum Agatston.

RESULTS

We included 168 patients (mean age 67.0 ± 10.5, 38 females) of whom 38 had normal kidney function, while 30, 40, 28, and 32 had CKD stages 3a, 3b, 4, and 5, respectively. Agatston scores adjusted for body surface area ranged from 48 to 40,165. We found that invCSBP increased 3.6 (95% confidence interval 1.4–5.7) mm Hg relative to cuffSBP for every 10,000-increment in aortic Agatston score. This association remained significant after adjustment for age, diabetes, antihypertensive treatment, smoking, eGFR, and BP level. No such association was found for diastolic BP.

CONCLUSIONS

Patients with advanced aortic calcification have relatively higher invCSBP for the same cuffSBP as compared to patients with less calcification. Advanced aortic calcification in CKD may therefore result in hidden central hypertension despite apparently well-controlled cuffSBP. ClinicalTrials.gov identifier: NCT04114695.
Convenient pre-separation method depends on negative charges suitable for glycan sequencing analysis
Authors: Segawa Shigemitsu , Natsuka Shunji
Published: March 2024

For precise structural analysis of complex glycans, it is necessary to fractionate glycans based on acidity prior to liquid chromatography-mass spectrometry analysis. Conventional fractionation using high-performance liquid chromatography is time consuming and not high throughput. Therefore, we developed a rapid method for the fractionation using a small cartridge column. This enables rapid multi-sample processing for glycan sequencing.
Functional support vector machine
Authors: Xie Shanghong , Ogden R Todd
Published: March 2024

Linear and generalized linear scalar-on-function modeling have been commonly used to understand the relationship between a scalar response variable (e.g. continuous, binary outcomes) and functional predictors. Such techniques are sensitive to model misspecification when the relationship between the response variable and the functional predictors is complex. On the other hand, support vector machines (SVMs) are among the most robust prediction models but do not take account of the high correlations between repeated measurements and cannot be used for irregular data. In this work, we propose a novel method to integrate functional principal component analysis with SVM techniques for classification and regression to account for the continuous nature of functional data and the nonlinear relationship between the scalar response variable and the functional predictors. We demonstrate the performance of our method through extensive simulation experiments and two real data applications: the classification of alcoholics using electroencephalography signals and the prediction of glucobrassicin concentration using near-infrared reflectance spectroscopy. Our methods especially have more advantages when the measurement errors in functional predictors are relatively large.
Hyperlink communities in higher-order networks
Authors: Lotito Quintino Francesco , Musciotto Federico , Montresor Alberto , Battiston Federico
Published: March 2024

Many networks can be characterized by the presence of communities, which are groups of units that are closely linked. Identifying these communities can be crucial for understanding the system’s overall function. Recently, hypergraphs have emerged as a fundamental tool for modelling systems where interactions are not limited to pairs but may involve an arbitrary number of nodes. In this study, we adopt a dual approach to community detection and extend the concept of link communities to hypergraphs. This extension allows us to extract informative clusters of highly related hyperedges. We analyse the dendrograms obtained by applying hierarchical clustering to distance matrices among hyperedges across a variety of real-world data, showing that hyperlink communities naturally highlight the hierarchical and multiscale structure of higher-order networks. Moreover, hyperlink communities enable us to extract overlapping memberships from nodes, overcoming limitations of traditional hard clustering methods. Finally, we introduce higher-order network cartography as a practical tool for categorizing nodes into different structural roles based on their interaction patterns and community participation. This approach aids in identifying different types of individuals in a variety of real-world social systems. Our work contributes to a better understanding of the structural organization of real-world higher-order systems.
Talking to Our Sons: The Power of the Reproductive Sphere in Agnès Agboton’s and Najat El Hachmi’s Autobiographies
Authors: Utiger Julia Teresa
Published: March 2024

In their autobiographies Más allá del mar de arena (2005) and Jo també sóc catalana (2004), Agnès Agboton and Najat El Hachmi narrate their diasporic experience of living and mothering in Catalonia. In both cases, the narrators address their sons. The close connection between the mothers (narrators) and their sons (addressees) establishes an intimate space of power which is analyzed through Irene Gedalof’s concept of the reproductive sphere. This essay proposes that the authors of both texts establish mothering in the diaspora within autobiographical narratives as a site of negotiation, creation of identity, and intervention both for the addressees and for a larger audience.
Highly Resolved Genomes of Two Closely Related Lineages of the Rodent Louse Polyplax serrata with Different Host Specificities
Authors: Martinů Jana , Tarabai Hassan , Štefka Jan , Hypša Václav
Published: March 2024

Sucking lice of the parvorder Anoplura are permanent ectoparasites with specific lifestyle and highly derived features. Currently, genomic data are only available for a single species, the human louse Pediculus humanus. Here, we present genomes of two distinct lineages, with different host spectra, of a rodent louse Polyplax serrata. Genomes of these ecologically different lineages are closely similar in gene content and display a conserved order of genes, with the exception of a single translocation. Compared with P. humanus, the P. serrata genomes are noticeably larger (139 vs. 111 Mbp) and encode a higher number of genes. Similar to P. humanus, they are reduced in sensory-related categories such as vision and olfaction. Utilizing genome-wide data, we perform phylogenetic reconstruction and evolutionary dating of the P. serrata lineages. Obtained estimates reveal their relatively deep divergence (∼6.5 Mya), comparable with the split between the human and chimpanzee lice P. humanus and Pediculus schaeffi. This supports the view that the P. serrata lineages are likely to represent two cryptic species with different host spectra. Historical demographies show glaciation-related population size (Ne) reduction, but recent restoration of Ne was seen only in the less host-specific lineage. Together with the louse genomes, we analyze genomes of their bacterial symbiont Legionella polyplacis and evaluate their potential complementarity in synthesis of amino acids and B vitamins. We show that both systems, Polyplax/Legionella and Pediculus/Riesia, display almost identical patterns, with symbionts involved in synthesis of B vitamins but not amino acids.