bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of sector specialisation on unlisted real estate fund performance amid economic downturns
Authors: Hilders Bas , Marx Simon , Tsolacos Sotiris
Published: September 2024

This study focuses on the relationship between fund performance, sector specialisation and the state of the economy in the unlisted European real estate fund sector. We construct a sector concentration index to measure the impact of sector specialisation on unlisted fund performance, measured by total returns, in Europe. Using the INREV database, our sample draws from 634 private real estate funds investing in European countries over the period 2000 to the end of 2021. After controlling for key factors influencing fund performance, we find a positive and statistically significant relationship, at the 10% level, between sector specialisation and fund performance. Specifically, fund managers who concentrate their resources on a smaller number of sectors tend to achieve stronger performance, and this result is not driven by any particular sector. An implication of this study is that the results could be conditional to the method selected to measure sector specialisation. A consistent finding across specifications is that a recession has a significant adverse impact on fund performance. The positive relationship between fund performance and total returns is weakened during recessions; however, this finding is not statistically significant. These tentative findings are particularly relevant for sector-specific funds, which lack the mandate to diversify into other sectors. To protect performance during recessions, such funds may need to consider alternative de-risking strategies, including increasing geographical diversification, optimising tenant mix, and deleveraging.
Kinetic model for stress in sputter-deposited alloy thin films and its application to the vanadium–tungsten alloy system
Authors: Su Tong , Thompson Gregory B. , Chason Eric
Published: September 2024

The use of thin films made of alloys, i.e., containing multiple metal species, can enhance their properties. However, as with single-element films, residual stress in the films can limit their performance. A model is proposed for relating the stress in alloy thin films to the processing conditions (growth rate, temperature, and sputter-gas pressure), material properties (composition, atomic and defect mobilities, and elastic moduli), and microstructure (grain size and grain growth kinetics). The model is based on stress-generating processes that occur during film growth at grain boundaries and due to energetic particle impacts. While the equations are similar to those proposed for single-element films, the alloy kinetic parameters now contain the effects of the different atomic species. The model is used to explain the growth rate and composition dependence of in situ stress evolution during the deposition for various concentrations in the tungsten–vanadium system.
Skyrmionium creation and annihilation: Experimental and micromagnetic simulation demonstration
Authors: Qiu Shan , Zhao Le , Fang Liang , Jiang Wanjun , Xu Wei , Zhu Zhihong , Liu Jiahao
Published: September 2024

Topological spin structures have recently received tremendous attention in condensed matter physics and information science. In addition to the frequently studied skyrmion, skyrmioniums that exhibit a zero topological charge are also promising for spintronics memory carriers. Here, through integrating an interfacial asymmetric Ta/CoFeB/MgO multilayer device with an on-chip conducting wire that induces Oersted fields and Joule heating, we show experimentally the creation and annihilation of magnetic Néel-type skyrmioniums at room temperature, without applying external magnetic fields. In particular, we observe two distinct annihilation dynamics of the skyrmionium by a polar magneto-optical Kerr microscope. Under the direction of Oersted fields that are parallel to the core direction of the skyrmionium, the skyrmionium shrinks inward to form a skyrmion. Under the antiparallel configuration, skyrmionium expands outward to form a stripe domain. By performing micromagnetic simulations, we reveal the Néel-type skyrmionium formation and annihilation dynamics as well as the corresponding energy changes among different magnetic states. Our findings could be important for understanding the formation and annihilation dynamics of skyrmioniums, which also provide an on-chip non-electrical-contact manipulating method of skyrmioniums.
Imaging hot photocarrier transfer across a semiconductor heterojunction with ultrafast electron microscopy
Authors: Shaheen Basamat S. , Huynh Kenny , Quan Yujie , Choudhry Usama , Gnabasik Ryan , Xiang Zeyu , Goorsky Mark , Liao Bolin
Published: September 2024

Semiconductor heterojunctions have gained significant attention for efficient optoelectronic devices owing to their unique interfaces and synergistic effects. Interaction between charge carriers with the heterojunction plays a crucial role in determining device performance, while its spatial-temporal mapping remains lacking. In this study, we employ scanning ultrafast electron microscopy (SUEM), an emerging technique that combines high spatial-temporal resolution and surface sensitivity, to investigate photocarrier dynamics across a Si/Ge heterojunction. Charge dynamics are selectively examined across the junction and compared to far bulk areas, through which the impact of the built-in potential, band offsets, and surface effects is directly visualized. In particular, we find that the heterojunction drastically modifies the hot photocarrier diffusivities in both Si and Ge regions due to charge trapping. These findings are further elucidated with insights from the band structure and surface potential measured by complementary techniques. This work demonstrates the tremendous effect of heterointerfaces on hot photocarrier dynamics and showcases the potential of SUEM in characterizing realistic optoelectronic devices.
VOCs conversion in He/H2O plasma produced in a micro-capillary tube at atmospheric pressure
Authors: Bauville G , Heninger M , Lemaire J , Jeanney P , Santos Sousa J , Pallandre A , Pasquiers S
Published: September 2024

A non-equilibrium plasma is created in a micro-capillary quartz tube (800 µm of internal diameter), by a DC-pulsed micro-dielectric barrier discharge (micro-DBD) and the propagation of an ionisation wave, in mixtures of He/H2O/VOC at atmospheric pressure where the studied volatile organic compounds (VOCs) are representative of molecules belonging to different chemical families: alcohols (methanol, ethanol, isopropanol, tert-butanol), ketones (acetone), nitriles (acetonitrile), and aromatic hydrocarbons (toluene). The conversion efficiency of these VOCs is studied as a function of the applied voltage on the micro-DBD (or electrical energy deposited in the plasma) and of the initial concentration of the molecules in the range from 1 ppm up to 3000 ppm (depending on the molecule), with the help of high-resolution real-time mass spectrometry Fourier transform ion cyclotron resonance associated to chemical ionisation (CI-FTICR) using H3O+ as precursor ion. A variety of by-products resulting from the conversion of VOCs are identified and quantified, emphasising that the micro-capillary plasma is able to induce a complex chemical reactivity. A qualitative analysis of the involved kinetics, based on the existing literature, reveals that helium species (ions and metastable states) and radicals coming from the dissociation of the water molecules (O and OH) are the most probable candidates to explain the formation of all compounds detected by the CI-FTICR apparatus. Quenching processes of the metastable He(23S) by the VOCs, leading to the dissociation of the molecules, are suggested to explain some of the experimental results.
Thermo-hydraulic-metallographic modeling and study of the thermotropic metamorphic layer in EDM of Ti–6Al–4V
Authors: Yin Mulong , Tang Jiajing , Li Zhengkai , Yue Xiaoming , Peng Weiye , Qiu Zhiwei , Bai Jicheng
Published: September 2024

An in-depth understanding of the microstructure evolution of the thermotropic metamorphic layer is the basis for effectively suppressing surface and subsurface defects in electrical discharge machining (EDM) of Ti–6Al–4V. In this work, the thermo-hydraulic-metallographic coupling model with successive pulse was established for the first time, based on which the visual simulation of time-variant phase transformation in recast layer and heat-affected zone (HAZ) was achieved. Further, the microstructure distribution characteristics in the thermotropic metamorphic layer were investigated from the perspective of experimental observation. The results show that with the accumulation of successive pulse discharges, the temperature on the processed surface gradually increases while the overall temperature distribution tends to be relatively uniform. The microstructure of the EDMed surface is characterized by a layered distribution, in which the recast layer undergoes complete α′-Ti (martensitic phase) transformation, and HAZ is composed of an upper layer with α′-Ti and a lower layer with α + β + α′ mixture. Meanwhile, it was revealed that the microstructure in the β grain of HAZ changed from a staggered distribution of the secondary α-Ti phase to a parallel distribution of the acicular α′-Ti phase. A transition layer composed of cellular martensite was observed between the recast layer and HAZ, and the internal grain showed a change from parallel arrangement to staggered arrangement as the peak current increased to a relatively larger level. The martensite volume fraction and microhardness of the thermotropic metamorphic layer have also been verified to correlate to the peak current. The combined study of the thermo-hydraulic-metallographic coupling model and insights into microstructure characteristics were expected to provide theoretical references for predicting and controlling the surface integrity in EDM of Ti–6Al–4V.
Dielectric metasurface Fresnel zone plates for polarization conversion
Authors: Zhang Tian , Wang Wei , Wang Jun , Chen Zhongyan , Lin Jie , Jin Peng , Liu Shutian , Zhou Keya
Published: September 2024

Conventional Fresnel zone plates (FZPs) can only achieve a single focusing function and require the combination with other optical elements to achieve multiple optical functions. This contradicts the development trends for miniaturized, integrated and multifunctional optical devices. However, the emergence of metasurfaces offers new solutions for this problem. In this paper, we design two different types of multifunctional metasurface Fresnel zone plates (MFZPs). One is based on amplitude modulation, and the other is based on phase modulation, both of which can achieve linear polarization conversion and focusing functions. The realization of these functions is based on the ability of silicon diatomic nanopillars to decouple and control the amplitude, phase, and polarization of electromagnetic waves. The designed ultrathin dielectric metasurface effectively combines the functions of conventional half-wave plates and FZPs, thereby reducing the volume of the optical system. The designed MFZPs have enormous potential for application in integrated and compact optical systems.
Radiation exposure of astronauts following an intense solar particle event: analysis and comparison of doses in male and female voxel phantoms
Authors: Ramos Ricardo Luis , Bernardini Elena , Carante Mario , Ferrari Alfredo , Sala Paola , Vercesi Valerio , Ballarini Francesca
Published: September 2024

According to NASA’s plans, a human travel to the Moon is planned by the end of 2025 with the Artemis II mission, and humans should land on the Moon again in 2026. Exposure to space radiation is one of the main risks for the crew members; while for these short missions the doses from galactic cosmic rays would be relatively low, the possible occurrence of an intense solar particle event (SPE) represents a major concern, especially considering that in 2025 the Sun activity will be at its peak. Quantifying the amount and the effects of such exposure is therefore crucial, to identify shielding conditions that allow respecting the dose limits established by the various space agencies. By exploiting an interface between the BIANCA biophysical model and the FLUKA Monte Carlo radiation transport code, in this work we implemented a male and a female voxel phantom and we calculated absorbed doses and Gy-Eq doses in the various tissues/organs, as well as effective doses, following exposure to the August 1972 SPE, the most intense event of the modern era. The calculations were performed respect the organ dose limits for 30 d missions. A detailed comparison between male and female doses was then carried out, also considering that the Artemis II crew will include a woman. The results showed that female doses tend to be higher than male doses, especially with light shielding. This should be taken into account in mission design, also considering that, in a typical lunar mission, up to 15% of time may be spent in extra-vehicular activities, and thus with light shielding. More generally, this work outlines the importance of performing separate calculations for male and female astronauts when dealing with radiation doses and effects.
Unsupervised bearing raceway surface defect detection based on improved f-AnoGAN
Authors: Zhang Yikang , Li Jiale , Li Junfeng , Pan Haipeng
Published: September 2024

For addressing bearing raceway surface defects, supervised deep learning methods face challenges such as insufficient defect samples and imbalance between defect and non-defect samples. To overcome these issues, we propose an enhanced fast anomaly detection with generative adversarial networks (f-AnoGAN) unsupervised detection algorithm. Firstly, SE-Block modules based on SE attention mechanism and residual structure are integrated into the encoder, aiding the network in focusing on channel information while alleviating gradient vanishing problems. Secondly, transfer learning is introduced to effectively enhance the algorithm’s detection performance and generalization ability. Finally, utilizing bearing images collected from industrial sites, a self-built bearing raceway surface defect dataset is constructed, and extensive experiments are conducted. Experimental results demonstrate that the improved algorithm achieves an area under curve score of 99.96% on the self-built bearing raceway surface defect dataset, representing a 7.07% improvement over the f-AnoGAN algorithm, meeting the requirements for online detection in bearing industry applications.
Developing and implementing an Einsteinian science curriculum from years 3–10: B. Teacher upskilling: response to training and teacher’s classroom experience
Authors: Kaur Tejinder , Kersting Magdalena , Adams Kyla , Blair David , Treagust David , Lonshakova Anastasia , Boublil Shon , Santoso Jesse , Ju Li , Zadnik Marjan , Wood David , Horne Elaine , McGoran Darren , Scott Susan , Venville Grady
Published: September 2024

Recent years have seen a growing interest in modernizing school science curricula to reflect the discoveries in physics since 1900, especially with the recent broad recognition of the importance of quantum physics in the modern world. Much effort has been expended in the development of appropriate teaching instruments for teaching Einsteinian physics in schools, but less effort on the crucial topic of teacher professional development. Successful curriculum innovation requires teacher professional development. This paper reports an analysis of teacher professional development for practising primary and secondary teachers who were upskilled as part of a process for implementing an 8-year Einsteinian curriculum across 38 primary and secondary schools in Australia. Most participants had little prior knowledge of Einsteinian physics. Using self-assessment through questionnaires and interviews, combined with classroom validation, we show that three different professional development programs led to high levels of content knowledge and confidence to teach Einsteinian physics in classes from Year 3 to Year 10. The analysis presented supports our conclusion that it is feasible to upskill teachers from diverse backgrounds in Einsteinian physics and break the cycle that has inhibited the modernisation of school curricula.
Assessing the validity of the ray model using sound reflection
Authors: Harb Tarek , Oreiby Hussein , Farah Oleg , Karishy Slyman , Sakr Salam
Published: September 2024

In this paper, we present a straightforward experiment using sound reflection to evaluate the validity of ray acoustic models. The ratio of the wavelength of sound waves to the focal length of the reflector (

λ

/

d

) is varied. For very small ratios, the wave nature is not manifested and the ray model can perfectly explain the outcomes. As this ratio increases, the ray model can only predict some aspects of the results. When

λ

/

d

reaches 0.4, the interference effects become dominant and consequently the ray model completely fails to explain the measurements.
Development of a Zappe-interferometer style superconducting switch for time-division multiplexed readout of transition edge sensor array
Authors: Li Taiyu , Xu Yuanxing , Wang Chaoqun , Tang Lihong , Zhang Huanqian , Xie Hangxing , Ying Liliang , You Lixing , Gao Bo , Wang Zhen
Published: September 2024

Time-division multiplexing constitutes a pivotal readout technique for arrays of transition edge sensors (TES). At the heart of constructing the multiplexing unit (Mux unit) lies a flux-actuated superconducting switch. The superconducting quantum interference device (SQUID) is ideally suited for this role due to its compatibility with the fabrication processes of the SQUID current amplifier, which is employed to read the TES signal. This compatibility facilitates the integration of the switches with the SQUID amplifiers on a single chip. Nevertheless, the critical current of a switch based on a conventional DC-SQUID exhibits abrupt changes with the control flux near the local minimum of the threshold curve, which is the typical operating point of the SQUID amplifier. Such abrupt changes compromise the stability of the SQUID amplifier’s operational point. To mitigate this issue, a Zappe interferometer-style switch design has been adopted, providing a threshold curve with a more pronounced flat region. In this work, we present the design and characterization of Zappe-style switches and demonstrate the operational efficacy of the Mux unit.
Design and implementation of dynamic s-boxes based on non-degenerate discrete chaotic systems
Authors: Xi Jiale , Fan Chunlei , Yu Guofeng
Published: September 2024

In recent years, digital chaotic systems have received considerable attention in the field of secure communications. However, during the digitalization of the system, the original properties of the chaotic system may change, resulting in the degradation of the dynamics. To address this problem, this paper designs a novel simplicial non-degenerate discrete chaotic system based on the inverse hyperbolic tangent function, and selects a three-dimensional discrete system as the object of analysis. Through the research conducted, it is found that the chaotic system exhibits high Lyapunov exponents under certain conditions. Furthermore, the excellent randomness of the system has been further validated by NIST SP800–22 tests. At the same time, this paper also proposes a dynamic S-box construction method based on the chaotic sequence generated from the three-dimensional chaotic mapping. By performing a series of basic operations and permutation treatment, many dynamic S-boxes can be generated. This paper comprehensively analyses the performance of S-boxes from two perspectives: single S-boxes and multiple S-boxes. The analysis covers issues such as bijective property, nonlinearity, strict avalanche criterion, differential approximation probability and bit independence criteria. The results of the performance analysis show that the dynamically generated S-boxes have excellent cryptographic properties, making them suitable for the design and application of cryptographic algorithms.
Effects of chemical etching on surface structure and tribological behavior of silicate substrates
Authors: Lee Sung-Jun , Segu Dawit Zenebe , Kim Chang-Lae
Published: September 2024

This study investigated the effect of chemical etching on the surface structure and tribological behavior of silicate substrates. Silicate surfaces were etched using a mixture of nitric acid (HNO3) and ammonium bifluoride (NH4HF2) for durations ranging from 1 to 60 min. The etched surfaces were characterized using optical microscopy, scanning electron microscopy, surface profilometry, water contact angle measurements, and UV–vis spectroscopy to evaluate the changes in surface morphology, roughness, wettability, and optical properties. Tribological performance was assessed using reciprocating ball-on-plate friction tests. The results showed that increasing the etching time resulted in the formation of microscale surface features, increased surface roughness, enhanced hydrophilicity, and reduced optical transmittance. The average friction coefficient decreased with an increase in the etching time up to 30 min, beyond which a slight increase was observed. The 1-minute etched specimen exhibited the best wear resistance with the narrowest wear track and the least material removal. The improved tribological performance was attributed to the formation of a stable transfer film, reduced real contact area, and entrapment of wear debris. This study highlights the potential of chemical etching as a technique to tailor the surface structure and tribological properties of silicate materials for various applications.
Low-profile robust circularly polarized textile patch antenna for WBAN and ISM applications
Authors: Mulaparti Meena Kumari , Kumari U V Ratna
Published: September 2024

In this research, a conformal circularly polarized (CP) antenna has been developed employing polyester textile as its substrate material. The proposed antenna configuration demonstrates its efficacy across multiple frequency bands—specifically 3 GHz and 4.5 GHz of WBAN and 5.8 GHz of ISM radio bands. The antenna’s distinctive design is developed on a rectangular plane as its primary radiating component, with a ground structure ingeniously arranged counter-positioning to the antenna’s patch. Electrical conductivity was widely achieved by employing adhesive copper and silver tape, conductive fabric, stitching conductive threads and copper paint, conventionally applied through brush painting techniques. The copper paint fabrication methodology has been chosen for its ability to confer conformability upon the antenna while minimizing its dimensions, ensuring lightweight attributes, and endowing it with remarkable resilience to environmental factors while preserving its optimal radiating performance. The CP polyester antenna showcases noteworthy peak gains: 3.91 dBi at 3 GHz, 5.86 dBi at 4.5 GHz and 6.62 dBi at 5.8 GHz (ISM). These gains highlight the antenna’s ability to efficiently capture and transmit signals within the aforementioned frequency bands, affirming its potential for robust wireless communication.
Non-uniform phase distribution of a tightly focused elliptically polarized vortex beam
Authors: Qasim Muhammad Javed , Liu Yu , Tao Shaohua
Published: September 2024

Tight focusing of elliptically polarized vortex beams has been previously studied for optical manipulation, optical information encoding, and so on. Still, there is a lack of research on the status of the phase distribution on the focal plane. In this study, we found that the phase distribution of a tightly focused elliptically polarized vortex beam is non-uniform, i.e., the phase distribution exhibits flatter and steeper regions due to the elliptical polarization of the input vortex beam. It is mentioned that the phase non-uniformity was related to the ellipticity of the polarization of the incident beam. Furthermore, we analyzed the intensity and phase distribution of a tightly focused elliptically polarized vortex beam. We found that the spin angular momentum was converted to the orbital angular momentum because the topological charge of the output beam was greater than that of the input beam. The non-uniform phase distribution of a tightly focused elliptically polarized vortex beam enables control over light–matter interaction, leading to advancements in optical tweezers, quantum information processing, and super-resolution microscopy.
Non-linear optical properties of hybrid materials of (OLi3) superalkali doped perylene diimide (PDI) derivative: comprehensively study via silico-technique
Authors: Ayub Ali Raza , Zeshan Muhammad , Salba  , Dad Muhammad Umar , Li Hui , Iqbal Javed
Published: September 2024

PDI-Imidazole and PDI-Imidazole combined with OLi3 (OLi3@PDI-Imidazole) were the two types of materials that we examined in this study to see how light behaved in each of the complex. To explore this, we employed the three different method such as rB3LYP/6–31G(d, p) DFT, CAM-B3LYP and WB97XD. The impact of PDI-Imidazole and OLi3@PDI-Imidazole geometries, maximum absorption (

λ

max

), FMO, vertical ionization energies (

E

V
I

), Binding Energies (

E

b

), Hyperpolarizabilities, DOS, Dipole Moments (μ), ESP, EDDM, and Global Reactivity parameters have been examined. The type of contacts as well as the vibrational frequencies of PDI-Imidazole and OLi3@PDI-Imidazole were investigated using NCl, iso-surface, Raman spectroscopy, and IR research. The electron transport characteristics of the OLi3@PDI-Imidazole surface was significantly enhanced in comparison to the PDI-Imidazole surface by lowering the bandgap energies from 1.27 eV to 1.03 eV. In contrast to the pure PDI-Imidazole surface, which had lower values for linear polarizability (

α

0

) (547.08 au) and first hyperpolarizability (

β

0

)(201.133au), OLi3@PDI-Imidazole surface displayed significant enhancements in linear polarizability (

α

0

= 706.472 au) and first hyperpolarizability (

β

0

= 21314.360 au). It was observed by TD-DFT calculations that all the compounds had appreciable improvements in their interaction energies, HOMO–LUMO and UV–vis absorption and vertical ionization potential. Future development of nonlinear optical (NLO) devices has been discovered to benefit from the addition of OLi3 to the PDI-Imidazole surface.
On the study of analytical soliton solutions and interaction aspects to the Estevez-Mansfield-Clarkson equation arising in diversity of fields
Authors: Muhammad Jan , Nasreen Naila , Hussain Ejaz , Younas Usman , Alsubaie Abdullah Saad
Published: September 2024

The beta fractional form of the Estevez-Mansfield-Clarkson equation is under consideration and this study is done with the assistance of methods such as modified F-expansion method and the logarithmic transformation. A variety of analytical solutions like bright, dark, mixed, singular, bright-dark, and combined solitons are extracted. Moreover, multi waves structures, interaction with double exponential form, breather waves, mixed type solutions as well as periodic cross kink solutions have been analyzed. The governing equation is converted into an ordinary differential equation by employing an appropriate wave transformation with the β-derivative in order to achieve the desired solutions. The applied approaches have substantial computational capability, enabling them to efficiently address exact solutions with high accuracy in these systems. The results indicate that the equation under investigation theoretically contains a substantial number of soliton solution structures. Additionally, in order to examine the behaviors of the solutions at various parameter values, we plot a variety of graphs that incorporate pertinent parameters. The results of this study have the potential to improve understanding of the nonlinear dynamic characteristics displayed by the specified system and to confirm the effectiveness of the techniques that have been implemented.
Investigation on effects of nano-reinforcement on the mechanical properties, fatigue, and microstructural analysis of dissimilar AA6061- Mg AZ31B weld joints
Authors: Gurijala Chakravarthi , Rajendran Ramadoss , Giridharan Krishnan
Published: September 2024

Weld joints have been subject to substantial improvement in mechanical durability and wear resistance in recent years. This research work challenge can be answered by incorporating nano-materials into the weld zone. Mechanical and metallurgical aspects of friction stir welded (FSW) butt joints made of AA6061 aluminum and Mg AZ31B alloys have been examined in this work, both with and without the use of naturally derived biochar nanoparticles. The biochar particle was extracted from rice husk. Throughout the whole weld joint manufacturing process, a tool with a rotational speed of 1400 rpm, a welding speed of 40 mm min−1, and a tapered pin profiled tool were employed. During the joint fabrication process, the constant axial load of 7 kN, plunge depth of 0.2 mm, and constant dwell time of 0.3 s were also maintained. In order to improve the mechanical attributes of the weld joints, different wt% of biochar such as 1%, 2%, and 3%, were applied at the interface region of the weld joints. The experimental results revealed that the percentage of reinforced nano-materials plays a significant effect in improving the weld joint qualities. The testing results of reinforced friction stir-welded joint qualities were compared to those of simple friction stir welded joints made without and with adding the nanoparticles. The best results were obtained when 2 wt% of biochar particles was added to the weld interface region. The presence of biochar nano-particles, in addition to their contribution to increased grain refinement in the weld nugget region, was also seen in the region. It was discovered that the event distribution of particles at the nugget zone significantly enhanced the mechanical and wear resistance qualities of the weld joints that were manufactured. The optical microscope was used to analyze the microstructures in the weld nugget region, and a scanning electron microscope (SEM) was utilized to examine the fracture analysis of the tensile samples. The presence of 2 wt% biochar particles in the weld nugget region resulted in a considerable increase in the mechanical characteristics of the weld connections. The ultimate tensile strength, hardness, and yield strength of the weld nugget results 197 MPa, 173 HV, 163 MPa. Overall, when compared to the qualities of the base material and plain weld joints. The mechanical properties and wear resistance of the weld joints have improved significantly. When biochar particles were used as reinforcement particles during the fabrication phase of the joint, a mechanism for pinning was observed in the weld microstructure.
Thermal wash-in leptogenesis via heavy Higgs decay
Authors: Mukaida Kyohei , Watanabe Hidenaga , Yamada Masaki
Published: September 2024

We present a conceptually simple model to generate asymmetries that are not directly related to baryon nor lepton charges. The model employs a three-Higgs doublet framework, wherein the other two Higgs fields are significantly heavier than the Standard Model (SM) Higgs field. The decay of these heavier Higgs fields generates asymmetry for approximately conserved charges in the Standard Model at a high temperature. These asymmetries will be converted into baryon/lepton asymmetry through B-L violating interactions associated with right-handed neutrinos via the wash-in mechanism.
Frequency shift of light in Kerr spacetime
Authors: Jiang Chunhua , Yang Bo , He Guansheng , Lin Wenbin
Published: September 2024

The frequency shift of light in the gravitational field generated by a rotating body is investigated. We consider the scenario in which both the light source and the observer are in motion. The frequency shift is calculated up to the second-order post-Minkowskian approximation via two different methods and the same result is achieved. The higher-order effects of the gravitational source's rotation on the frequency shift is obtained. Especially, when both the light source and the observer are located in the asymptotically flat region, an elegant formula is obtained, which can be easily used in the astronomical observations to determine the rotating gravitational source's mass and angular momentum.
Reconciling cosmological tensions with inelastic dark matter and dark radiation in a U(1)Dframework
Authors: Cho Wonsub , Choi Ki-Young , Mahapatra Satyabrata
Published: September 2024

We propose a novel and comprehensive particle physics framework that addresses multiple cosmological tensions observed in recent measurements of the Hubble parameter,S8, and Lyman-αforest data. Our model, termed `SIDR+zt' (Self Interacting Dark Radiation with transition redshift), is based on an inelastic dark matter (IDM) scenario coupled with dark radiation, governed by a U(1)Dgauge symmetry. This framework naturally incorporates cold dark matter (DM), strongly interacting dark radiation (SIDR), and the interactions between these components. The fluid-like behavior of the dark radiation component which originates from the self-quartic coupling of the U(1)Dbreaking scalar can suppress the free-streaming effects. Simultaneously, the interacting DM-DR system can attenuate the matter power spectrum at small scales. The inelastic nature of DM provides a distinct temperature dependence for the DM-DR interaction rate determined by the mass-splitting between the inelastic dark fermions which is crucial for resolving the Ly-αdiscrepancies. We present a cosmologically consistent analysis of the model by solving the relevant Boltzmann equations to obtain the energy density and number density evolution of different species of the model. The DR undergoes two “steps” of increased energy density when the heavier dark species freeze out and become non-relativistic, transferring their entropy to the dark radiation and enhancing ΔNeff. The analysis showcases the model's potential to uphold the Big Bang Nucleosynthesis (BBN) prediction of ΔNeffbut dominantly producing additional contributions prior to recombination, while simultaneously achieving correct relic density of DM though an hybrid of freeze-in and non-thermal production.
Constraining bosonic dark matter-baryon interactions from neutron star collapse
Authors: Lu Chih-Ting , Mishra Arvind Kumar , Wu Lei
Published: September 2024

Dark matter (DM) may be captured around a neutron star (NS) through DM-nucleon interactions. We observe that the enhancement of such capturing is particularly significant when DM-nucleon scattering cross-section depends on the relative velocity and/or momentum transfer. This increment could potentially lead to the formation of a black hole within the typical lifetime of the NS. As the black hole grows through the accretion of matter from the NS, it ultimately results in the collapse of the host. Utilizing the existing pulsar data J0437-4715 and J2124-3858, we derive the stringent constraints on the DM-nucleon scattering cross-section across a broad range of DM masses.
Correspondence between grey-body factors and quasinormal modes
Authors: Konoplya R.A. , Zhidenko A.
Published: September 2024

Quasinormal modes and grey-body factors are spectral characteristics corresponding to different boundary conditions: the former imply purely outgoing waves to the event horizon and infinity, while the latter allow for an incoming wave from the horizon, thus describing a scattering problem. Nevertheless, we show that there is a link between these two characteristics. We establish an approximate correspondence between the quasinormal modes and grey-body factors, which becomes exact in the high-frequency (eikonal) regime. We show that, in the eikonal regime, the grey-body factors of spherically symmetric black holes can be remarkably simply expressed via the fundamental quasinormal mode, while at smallerℓ, the correction terms include values of the overtones. This might be interesting in the context of the recently observed connection between grey-body factors and the amplitudes of gravitational waves from black holes. The correspondence might explain why grey-body factors are more stable, i.e. less sensitive, than higher overtones to small deformation of the effective potential.
In-line fiber optic optofluidic sensor based on a fully open Fabry-Perot interferometer
Authors: Duan Dewen , Kang Qian , Yang Qianhui , Zhao Zihao , Li Na , Du Guan-Xiang , Xie Yi-Yuan
Published: September 2024

We present an all-fiber, fully open Fabry–Perot interferometer (FPI) cavity that is suitable for fluidic measurement applications. Fabrication of the FPI involves the alignment and bonding of three optical fiber sections using either ceramic glue or low-temperature melting glass. The fabrication procedure allows the protection of the cleaved optical fiber end faces, which serve as the two mirrors of the FPI, from damage, thus ensuring the high visibility of the FPI sensor. The FPI’s complete openness permits the analyte of interest fluids to flow smoothly into the cavity and interact directly with the light, obviating the need for additional assistance. The fabrication experiment demonstrates that the fabrication procedure can readily achieve a visibility of over 20 dB. Refractive index testing indicates that the sensor exhibits a sensitivity of over 1116 nm/RIU within the range of 1.334–1.375. A comparison of temperature investigations indicates that the fully open cavity FPI fabricated by bonding with low-temperature melting glass exhibits relatively lower temperature immunity than that bonded with ceramic glue. Both have a relatively low temperature fluctuation within the temperature range of 40 °C–100 °C, with less than 3 nm and 4.5 nm in the over 60 °C changes, respectively. Our proposed fully open FPI is an economical, robust, and simple-to-fabricate structure with the potential for mass production. This renders it an appealing option for practical optofluidics applications.
A fractional-order chaotic Lorenz-based chemical system: Dynamic investigation, complexity analysis, chaos synchronization, and its application to secure communication
Authors: Nabil Haneche , Tayeb Hamaizia
Published: September 2024

Synchronization of fractional-order chaotic systems is receiving significant attention in the literature due to its applications in a variety of fields, including cryptography, optics, and secure communications. In this paper, a three-dimensional fractional-order chaotic Lorenz model of chemical reactions is discussed. Some basic dynamical properties, such as stability of equilibria, Lyapunov exponents, bifurcation diagrams, Poincaré map, and sensitivity to initial conditions, are studied. By adopting the Adomian decomposition algorithm (ADM), the numerical solution of the fractional-order system is obtained. It is found that the lowest derivative order in which the proposed system exhibits chaos is q = 0.694 by applying ADM. The result has been validated by the existence of one positive Lyapunov exponent and by employing some phase diagrams. In addition, the richer dynamics of the system are confirmed by using powerful tools in nonlinear dynamic analysis, such as the 0–1 test and C
0 complexity. Moreover, modified projective synchronization has been implemented based on the stability theory of fractional-order systems. This paper presents the application of the modified projective synchronization in secure communication, where the information signal can be transmitted and recovered successfully through the channel. MATLAB simulations are provided to show the validity of the constructed secure communication scheme.
Sizing of an On-site Hydrogen Refueling System for a Fleet of Fuel Cell Buses in Dhulikhel-Kathmandu Route
Authors: Kafle Nawaraj , Phuyal Tej Prasad , Dhrubabar Singh K.C , Niroula Sagar , Sakhya Nashla , Singh Thapa Biraj
Published: September 2024

Nepal’s heavy-duty vehicle fleet relies entirely on imported fossil fuels, posing significant environmental risks due to high particulate matter (PM) emissions. Battery-powered alternatives are unsuitable for large fleets due to trade-offs between range and vehicle weight, which is not an issue for hydrogen-powered fuel cell electric vehicles (FCVs). Shifting to hydrogen fuel offers a promising solution for sustainable, emission-free heavy-duty vehicle operation. Fuel cell buses (FCBs) represent a transformative step in transportation, prioritizing environmental protection, decarbonization, and achieving net-zero carbon emissions by 2045. This paper reviews the critical components for developing an on-site hydrogen refueling station (OHRS). It analyzes the power requirements of vehicles operating on inclined roads based on vehicle modeling. By studying existing diesel buses on the route, the specifications needed for FCBs are determined. It involves Excel-based calculations of fuel demand, vehicle drive cycle modeling, infrastructure assessment, and capacity determination for a fleet of ten hydrogen buses. The analysis reveals that the maximum tractive power required is 119.85 kW, with buses averaging a velocity of 6.8 m/s, reaching a maximum of 20.75 m/s, and achieving a maximum acceleration of 0.96 m/s2. The average motor power required is 13.09 kW, with a maximum of 151.48 kW. Each bus requires 8 kg of hydrogen per day, necessitating an OHRS capable of producing 80 kg per day for a fleet of 10 buses. Consequently, the sizing of components such as the electrolyzer, compressor, storage, and dispenser is dictated by a hydrogen production flow rate of 4 kg per hour. This study provides a comprehensive framework for implementing and operationalizing OHRS to support the deployment of FCBs in heavy-duty transportation.
Design of Force Sensitive Resistor (FSR) embedded insole for phase detection during human gait and its classification
Authors: Pant U , Baral S , Gupta A , Shrestha P L
Published: September 2024

Gait analysis is the study of human motion during walking or running. It is often used to evaluate and treat individuals with movement disorders or to assist in the design of prosthetics and other assistive devices. The phase detection aspect of gait allows for the quantification of gait characteristics, assessment of effectiveness of interventions and monitoring the changes in gait over time. The objective of the paper is the design and development of a Force Sensing Resistor (FSR) embedded insole that can be placed in shoes for detection of phases during the human gait and its classification. The classification using FSR is achieved by placing sensors at strategic locations on the foot, to detect the forces applied during walking. The data collected by these sensors are used to identify specific phases of the gait cycle—particularly heel strike, midstance, toe-off and swing, by analysing the patterns of data during movement. The layout and number of FSRs is determined through literature review and is followed by the insole fabrication. The wireless transmission of gait data through the FSRs is actuated for ten healthy adults. Machine Learning (ML) program is consequently developed based on all available classification algorithms of supervised learning namely—Logistic Regression, Naïve Bayes, Decision Tree, Random Forest and Support Vector Machine (SVM). The algorithm is trained and tested on separate FSR data sets from which the predictive decision in each gait cycle is attained. In the phase classification aspect, SVM, Naïve Bayes, and Random Forest achieved the highest accuracy of 91.54%, followed by Decision Tree at 90.77% and Logistic Regression at 89.23%. In conclusion, the optimal number of FSRs and their location in smart insole for gait phase detection is resolved. Gait phase classification is also attained. FSR embedded insole thus, provides a promising solution in accurately identifying and categorizing gait phases.
Using rare event algorithms to understand the statistics and dynamics of extreme heatwave seasons in South Asia
Authors: Le Priol Clément , Monteiro Joy Merwin , Bouchet Freddy
Published: September 2024

Computing the return times of extreme events and assessing the impact of climate change on such return times is fundamental to extreme event attribution studies. However, the rarity of such events in the observational record makes this task a challenging one, even more so for ‘record-shattering’ events that have not been previously observed at all. While climate models could be used to simulate such extremely rare events, such an approach entails a huge computational cost: gathering robust statistics for events with return time of centuries would require a few thousand years of simulation. In this study, we use an innovative tool, rare event algorithm, that allows us to sample numerous extremely rare events at a much lower cost than direct simulations. We employ the algorithm to sample extreme heatwave seasons, corresponding to large anomalies of the seasonal average temperature, in a heatwave hotspot of South Asia using the global climate model Plasim. We show that the algorithm estimates the return levels of extremely rare events with much greater precision than traditional statistical fits. It also enables the computation of various composite statistics, whose accuracy is demonstrated through comparison with a very long control run. In particular, our results reveal that extreme heatwave seasons are associated with an anticyclonic anomaly embedded within a large-scale hemispheric quasi-stationary wave-pattern. Additionally, the algorithm accurately represents the intensity-duration-frequency statistics of sub-seasonal heatwaves, offering insights into both seasonal and sub-seasonal aspects of extreme heatwave seasons. This innovative approach could be used in extreme event attribution studies to better constrain the changes in an event’s probability and intensity with global warming, particularly for events with return times spanning centuries or millennia.
A rapid response process for evaluating causes of extreme temperature events in the United States: The 2023 Texas/Louisiana heat wave as a prototype
Authors: Schreck III Carl J , Easterling David R , Barsugli Joseph J , Coates David A , Hoell Andrew , Johnson Nathaniel C , Kunkel Kenneth E , Labe Zachary M , Uehling John , Vose Russell S , Zhang Xiangdong
Published: September 2024

As climate attribution studies have become more common, routine processes are now being established for attribution analysis following extreme events. This study describes the prototype process being developed through a collaboration across National Oceanic and Atmospheric Administration (NOAA), including monitoring tools as well as observational and model-based analysis of causal factors. The prolonged period of extreme heat in summer 2023 over Texas, Louisiana and adjacent areas provided a proving ground for this emerging capability. This event posed unique challenges to the initial process. The extreme heat lasted for most of the summer while most heat wave metrics have been designed for 3–7 d events. The eastern portion of the affected area also occurred within the so-called summer-time daytime warming hole where the warming trend in maximum temperatures has been mitigated wholly or in part by increased precipitation. The extreme temperature coincided with a strong—but not record—precipitation deficit over the region. Both observations and climate model simulations illustrate that the temperatures for a given precipitation deficit have warmed in recent decades. In other words, meteorological droughts today are hotter than their historical analogs providing a stronger attribution to anthropogenic forcing than for temperature alone. These findings were summarized in a prototype plain language report that was distributed to key stakeholders. Based on their feedback, the monitoring and assessment tools will continue to be refined, and the project is exploring other climate model large ensembles to increase the robustness of attribution for future events.
Even singular integral operators that are well behaved on a purely unrectifiable set
Authors: Jaye Benjamin , Vempati Manasa
Published: September 2024

We prove the existence of a

(
d
−
2
)

(d-2)

-dimensional purely unrectifiable set upon which a family of even singular integral operators is bounded.