bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental study of bubble growth and detachment behavior under different constraint strengths in a von Kármán swirling flow
Authors: Qiao Shuai , Cai Chujiang , Pan Chong , Liu Yanpeng
Published: November 2024

This work advances the systematic study of the mechanism by which a circular wettability dividing line (WDL) constrains the three-phase contact line of a growing bubble on a surface. This provides critical insights for improving the stability of air layers on superhydrophobic surfaces by discretization, which is essential for improving the application of superhydrophobic surfaces in drag reduction. The effects of two constraint parameters—the radius of the WDL and the size of the surface microstructures—on the growth and detachment behavior of bubbles in a von Kármán swirling flow were experimentally analyzed. The results show that as the WDL radius is increased from 2 to 8 mm, the additional constraint force it generates is weakened, leading to increases in the coefficient of variation of the bubble detachment volume, tilt angle, and asymmetry ratio, and a decrease in its maximum contact width. As the microstructure period is increased from 50 to 100 μm, the number of pinning points provided by the WDL for the three-phase contact line decreases, weakening the constraint force. Consequently, the coefficient of variation of the bubble detachment volume and the asymmetry ratio increase, while the tilt angle and maximum contact width decrease. Finally, as both the radius of the WDL and the size of the microstructures increase, the inertial force grows more rapidly than the buoyancy force at the moment of bubble detachment, resulting in a higher ratio of horizontal to vertical bubble displacement.
Electronic state back action on mechanical motion in a quantum point contact coupled to a nanomechanical resonator
Authors: Shevyrin Andrey A. , Bakarov Askhat K. , Shklyaev Alexander A. , Pogosov Arthur G.
Published: November 2024

In a nanomechanical resonator coupled to a quantum point contact, the back action of the electronic state on mechanical motion is studied. The quantum point contact conductance changing with subband index and the eigenfrequency of the resonator are found to correlate. A model is constructed explaining the frequency deviations by the variable ability of the quantum point contact to screen the piezoelectric charge induced by mechanical oscillations. The observed effects can be used to develop electromechanical methods for studying the density of states in quasi-one-dimensional systems.
Experimental investigation on the freezing characteristics of a droplet impacting a cold surface
Authors: Gao Shu-Rong , Shi Shi-Hua , Wang Yu-Xiang , Liu Zhe , Wei Bo-Jian , Yang Yan-Ru , Wang Xiao-Dong
Published: November 2024

Freezing after droplets impact cold surfaces is very common in real-life and industrial applications. In this study, via experimental methods, the freezing characteristics of a water drop impacting a supercooled substrate are studied. Effects of the Weber number and surface supercooling on the freezing diameter, freezing height, and freezing time are analyzed, respectively. Interestingly, both the freezing diameter and the freezing height are closely dependent on the We number, whereas they are independent of the surface temperature, due to the inertial force playing a leading role in the dynamic process of the impact droplet. While the freezing time is affected by the surface temperature and the Weber number. For small Weber numbers at We = 3.6–21.8, the freezing time drops with the decrease in surface temperature; while for large Weber numbers at We = 21.8–109.1, the influence of surface temperature on the contact time can be ignored. Based on this, a quantitative relationship between these freezing parameters and the impact Weber number is preliminarily established. This study will reveal the coupling mechanics of impact dynamic and freezing dynamic and quantitatively calculate the freezing characteristics, guiding the design of anti-icing surfaces.
Investigation on flow instability in the hump region of the large vertical centrifugal pump under cavitation conditions based on proper orthogonal decomposition
Authors: Yang Gang , Zhang Desheng , Shen Xi , Pan Qiang , Pang Qingzhao , Lu Qinghui
Published: November 2024

Complex flow patterns in a large vertical centrifugal pump (LVCP) when operating in the hump region under cavitation conditions should deserve more attention. This research investigates the interaction between cavitation and vortices in LVCP from the perspective of rigid vortex transport characteristics and modal decomposition. The hump characteristics of LVCP are more pronounced under cavitation. The backflow vortex cavitation at the impeller inlet and the leading edge cavitation of the diffuser vanes can be found under part-load conditions. Rigid vortex analysis reveals the low pressure backflow vortices are generated between the impeller inlet and the inlet pipe. The fusion of leading edge separation vortices with pressure surface separation vortices and shedding high pressure trailing edge separation vortices in the diffuser generates the unique stall vortices with a high pressure gradient. Under part-load conditions, the combination of rigid vortex stretching, rigid vortex dilation (RVD), coriolis force, and baroclinic torque (BT) cause further increase in the strength of cavitation tail vortices. The RVD and BT caused by diffuser vanes leading edge cavitation can accelerate the development and fusion of leading edge separation vortices, pressure surface separation vortices, and trailing edge separation vortices in the diffuser, then generate unique stall vortices with high pressure gradient in advance. Proper orthogonal decomposition analysis indicates that the unique stall vortices in the diffuser occupy the main energy of the flow pattern. The flow pattern in the diffuser is superimposed by a variety of vortices with different frequency characteristics, and these vortices show a particular low frequency signal well below fn. The cavitation at the diffuser vanes leading edge interacts with vortices to induce leading edge separation vortices and unique stall vortices with low frequency characteristics more easily, and these vortices always dominate the flow pattern evolution.
Influence of cavitation erosion on crack propagation behavior of hydraulic concrete under tensile stress
Authors: Yu Hao , Zhang Xiao , Sun Yuxue , Liu Yanshun , Zhang Yu , Guo Deyu , Yin Zhanchao , An Qiyi
Published: November 2024

Cavitation erosion is a significant issue in hydraulic concrete structures, particularly in high-flow and high-water-pressure environments. This study is aimed at examining the erosion effects of cavitation bubble collapse on concrete structures, as well as its influence on crack propagation behavior under tensile stress. By employing ultrasonic excitation of bubble clusters, this study examines the variations in macro- and microstructure, mass loss, and tensile splitting strength of concrete over time during cavitation. Furthermore, acoustic emission technology is utilized to analyze the evolution of internal cracks in concrete subjected to tensile stress after cavitation treatment. The findings reveal that cavitation leads to the sequential detachment of cement and aggregate, resulting in the formation of dense interconnected pits and cracks on the surface. During the testing period, the tensile splitting strength of C20, C40, and C60 concrete specimens decreased by 45.99%, 25.92%, and 18.91%, respectively. In the Brazilian splitting test, initial and linear elastic stages of loading show that preexisting cavitation-induced cracks rapidly extend and penetrate at low stress levels, with new cracks forming more frequently and predominantly as small cracks. Approaching the stress peak, the failure is attributed to the long-term accumulation of damage from multiple defects rather than instantaneous crack propagation. Additionally, the proportion of tensile cracks significantly increases, making the specimens more susceptible to failure under tensile stress and resulting in a marked decline in tensile performance. This study highlights the impact of structural changes and the degradation of split tensile strength in concrete due to cavitation on crack evolution behavior under tensile stress. It provides valuable insight for the assessment and maintenance of hydraulic concrete structures.
Unveiling hidden scaling relations in dissipative relaxation dynamics of strongly correlated quantum impurity systems
Authors: Ding Xu , Zhang Daochi , Zhang Hou-Dao , Zheng Xiao , Yan YiJing
Published: November 2024

Understanding the time evolution of strongly correlated open quantum systems (OQSs) in response to perturbations (quenches) is of fundamental importance to the precise control of quantum devices. It is, however, rather challenging in multi-impurity quantum systems because such evolution often involves multiple intricate dynamical processes. In this work, we apply the numerically exact hierarchical equations of motion approach to explore the influence of two different types of perturbations, i.e., sudden swapping of the energy levels of impurity systems and activating the inter-impurity spin-exchange interaction, on the dissipation dynamics of the Kondo-correlated two-impurity Anderson model over a wide range of energetic parameters. By evaluating the time-dependent impurity spectral function and other system properties, we analyze the time evolution of the Kondo state in detail and conclude a phenomenologically scaling relation for Kondo dynamics driven by these perturbations. The evolutionary scaling relationship is not only related to the Kondo characteristic energy TK but also significantly affected by the simultaneous non-Kondo dynamic characteristic energy. We expect these results will inspire subsequent theoretical studies on the dynamics of strongly correlated OQSs.
Improved gate reliability of normally off p-GaN gate HEMTs with in situ SiN cap-layer
Authors: Zhang Ga , Zhao Shenglei , Song Xiufeng , Yu Longyang , Sun Xuejing , Cao Chuangzhe , You Shuzhen , Liu Zhihong , Hao Yue , Zhang Jincheng
Published: November 2024

The gate reliability of p-GaN gate high electron mobility transistors (HEMTs) was investigated in this Letter. Compared with conventional p-GaN gate HEMT, the in situ SiN cap-layer on the p-GaN layer can lift up the energy band and form a metal–insulator–semiconductor structure. With the introduction of an in situ SiN cap-layer, the DC electrical characteristics and reliability have been significantly improved. The reverse gate leakage current is reduced by 3 orders of magnitude. The threshold voltage shifts from 1.67 to 3.25 V, the on-resistances increased from 8.7 to 9.9 Ω mm, and the gate breakdown voltage is improved from 10.2 to 16.3 V. After conducting time-dependent gate breakdown measurement and predicting lifetime with a 10-year failure rate of 63%, it is calculated that the maximum allowable gate voltage increased from 6.3 to 11.4 V. The 10-year gate voltage swing has improved from 4.63 to 8.15 V. In addition, the in situ SiN HEMT exhibits good stability under high temperatures and long-term stress tests. The experimental results demonstrate that the in situ SiN cap-layer offers significant advantages in gate reliability.
Numerical simulation and experimental study of energy dissipation in a bidirectional axial extended tubular pump with different blade angles
Authors: Jin Yan , Li Jian , Song Xijie , Sun Dandan , Chen Hongcheng
Published: November 2024

Bidirectional axial extended tubular pumps (BAETPs) are used in low-head pumping stations. This work used both experiments and numerical simulation to investigate the energy dissipation of BAETPs with various blade angles (the blade angle significantly impacts energy loss). Results show that the impeller produces the highest entropy compared with the other pump components. At blade angles of 0°, −2°, and −4°, the unit produces an entropy of 262, 197, and 144 W/K. As the blade angle increases, the ratio of entropy production in the impeller to the total entropy production of the pump steadily rises, the same ratio for the guide vane remains constant at 25%, and the ratio for the S-shaped elbow decreases sharply. Turbulent entropy production rate in the impeller is primarily concentrated in the blade inlet and outlet. Wall entropy production rate in the impeller is focused on the inlet edge of the impeller blade and tip clearance. High entropy production rate (HEPR) occurs at the blade tail due to the rotation of impeller and tip clearance leakage at the area between the impeller and guide vane. Inside the guide vane, the highest entropy production occurs at the guide vane outlet. The HEPR zone on the suction surface of the guide vane is curved and shifts gradually toward the center of the guide vane passage.
Defect evolution and nitrogen incorporation in ion-implanted β-Ga2O3
Authors: Azarov Alexander , Galeckas Augustinas , Mikhaylov Alexey , Nikolskaya Alena , Tetelbaum David , Korolev Dmitry , Monakhov Eduard , Kuznetsov Andrej
Published: November 2024

Nitrogen plays an important role in the Ga2O3-based device fabrication since it demonstrates a deep acceptor behavior and it can be used as a compensation impurity. In the present work, we introduced N into the monoclinic β-Ga2O3 single crystals by ion implantation using different dose-rates. The thermal evolution of the structural and optical properties of the implanted samples was studied by combining Rutherford backscattering/channeling spectrometry and x-ray diffraction with photoluminescence spectroscopy. We demonstrate that crystal disorder in N-implanted β-Ga2O3 is a strong function of ion flux even for room temperature implantation. Unlike other implanted species, the defect annealing kinetics for N exhibit a distinct two-stage behavior, where the low-temperature stage (<400 °C) is characterized by a rapid defect annealing, whereas the radiation defects exhibit a very slow evolution at the elevated temperatures (>400 °C). These trends are discussed in the framework of the disorder stabilization induced by the incorporation of the implanted N atoms into the Ga2O3 lattice. The obtained results can be used to better understand the interaction between N and intrinsic defects as well as to push forward the development of β-Ga2O3-based electronic devices.
High-sensitivity THz evanescent field sensing of biomolecules using on-chip systems
Authors: Hong Binbin , Meng Kun , Qiu Yanbing , Zeng Zhaohui , Robertson Ian , Cunningham John , Somjit Nutapong
Published: November 2024

We present a terahertz (THz) sensing chip capable of detecting trace biomolecules. Its operating bandwidth stretches from 0.2 to 1.35 THz, capable of signal strengths exceeding 38 dB above noise levels, achieved by the mitigation of mode competition issues. The high sensitivity of the sensing chip is used to observe the absorption fingerprints of α-lactose monohydrate, L-tyrosine, and L-histidine powders at their characteristic frequencies for sample masses as low as 0.3 mg. Using a solution titration technique, we demonstrate detection of the absorption fingerprint of α-lactose monohydrate for concentrations of 72 μg/μl, adding just 57.6 μg of the powder onto the chip after evaporation of the ethanol solvent, representing a twofold advancement over prior work by providing a significantly broader operating spectrum and higher sensitivity. The relatively easy manufacturability, low cost, and scalability of the sensing chip paves the way for studies of enhanced light–matter interaction between THz waves and trace analytes, while also unlocking innovative potential applications in biomolecular sensing, medical diagnostics, and environmental monitoring.
The evolution of Traditional Chinese Medicine as recombinant inventions
Authors: Wu Min , Ma Tieju , Zhu Yan , Ren Hongtao , Fu Lu
Published: November 2024

It has been widely recognized that technologies evolve with recombinant inventions. However, it remains unknown whether technologies developed using different approaches would exhibit different features during evolution. In particular, would technologies developed mainly based on accumulated experience in practices—formulas of traditional Chinese medicine (TCM) are typical examples of such technologies—have similar evolution features found in modern technologies? This study applied network science to explore the evolution of TCM from the perspective of recombinant inventions based on 59,063 TCM formulas documented over the last two thousand years, with each formula being a combination of components that are mostly herbs. Our results show that similar to modern technological systems, the TCM component networks maintained the core–periphery structures during evolution, and the (weighted) degrees of components followed heavy-tailed distributions. Moreover, simple tuples, which are frequently used combinations of TCM components, serve as building blocks for complex ones. A significant difference with modern technological systems is that the TCM core components were quite stable, while substitutions of core components are frequently observed in modern technological systems, leading to new technological trajectories. TCM comprises ancient knowledge and wisdom. This research provides insight into how it will be like in the future and what is important for its future.
Competitive degradation process based monitoring of steer-by-wire system under unknown degradation features
Authors: Lan Dun , Yu Ming , Wang Hai , Zhang Bin
Published: November 2024

Monitoring of steer-by-wire (SBW) system under intermittent faults is challenging since it is difficult to obtain the priori knowledge of monotonous degradation feature of intermittent fault due to its stochastic nature. To deal with this issue, this paper develops a prognosis method for the SBW system under unknown degradation features based on the concept of competitive degradation process (CDP). With the aid of fault diagnosis module, the possible faulty components can be determined, where the fault isolation estimators and the expanded analytical redundancy relations are used to improve the isolabilities of sensor faults. For each faulty component, three degradation features are defined and the monotonicity of each feature is unknown beforehand. To judge the monotonicity of the feature, the competition index is developed in the CDP and the feature is applicable (i.e. monotonous) if the predefined criterion can be satisfied using the established dataset of the feature. Once the applicable features are determined, the corresponding degradation models are built for remaining useful life prediction. Experiment results are presented to illustrate the performance of the proposed method.
A firefly-based particle filter technique for system state estimation and battery RUL prediction
Authors: Ahwiadi Mohamed , Wang Wilson
Published: November 2024

Accurate measurement and estimation of state variables in nonlinear dynamic systems are critical in various engineering and scientific applications. While particle filter (PF) techniques have become increasingly popular for modeling such dynamic systems, they are prone to sample degeneracy and impoverishment, which can considerably affect performance. Existing PF methods often come with drawbacks like high computing costs and noise sensitivity. This paper presents a novel probabilistic posterior optimization particle filter (PPO-PF) technique, inspired by the firefly algorithm, to address these PF limitations and enhance PF efficiency. In the proposed PPO-PF technique, an adaptive search method is proposed to locate the high-likelihood region within the posterior space for improved convergence. A new step size selection method is suggested to facilitate navigation within the search space. In addition, a particle position optimization approach is proposed to guide low-weight particles towards high-probability regions, optimizing the posterior probability density function and mitigating sample degeneracy. The proposed PPO-PF technique is validated by simulation under various model conditions, including predicting the remaining useful life of Lithium-ion (Li-ion) batteries. The results indicate that the proposed PPO-PF reliably captures system dynamics with improved accuracy, even under high noise conditions. These findings highlight its potential to enhance measurement science by offering a more reliable approach for state estimation in complex systems.
Minimization of melt-pool field variables fluctuation during selective laser melting of Ti6Al4V alloy through computational investigation
Authors: Weldeanenia Kidu Gebrecherkos , Kassegne Samuel Kinde , Perumalla Janaki Ramulu
Published: November 2024

The optimization of selective laser melting (SLM) process parameters for a new material through experiments is a time-consuming and challenging process. Computational approaches, on the other hand, offer an economical and relatively faster approach to effectively predict the influences of process factors on the behaviors of the field variables of SLM process. In this work, multiphysics models built using COMSOL software were used to carry out optimization of SLM-Ti6Al4V processes through a single-level setup method followed by a parametric sweep optimization (PSO) approach. The simulated results of the melt pool field variables obtained from both approaches were compared. In the PSO approach, the melt pool velocity was found to have 14.3% higher flow and 78.8% reduction in the transient velocity fluctuation amplitude within the melt pool region. The average transient temperature of the melt pool region was found to have 5.9% increase and 36.4% reduction in the average fluctuation amplitude along the solidus and peak points, respectively. On the other hand, the associated temperature gradient was found to have a fluctuation amplitude reduction of 15.3% at the maximum side of the melt pool region. Finally, the optimal solutions of the melt pool field variables obtained from the PSO were compared with published data to verified the approach. The reductions in temperature and thermal gradient results were found by 18.3% and 28.5% respectively in the melt pool region of the current SLM-Ti6Al4V process and, hence, validating the predictions of the PSO technique.
The global well-posedness of the relativistic Boltzmann equation with hard potentials and diffuse reflection boundary condition in bounded domains
Authors: Wang Yong , Xiao Changguo , Yong Yan
Published: November 2024

In the present paper, assuming that the motion of single-species relativistic particles in a bounded domain is governed by the relativistic Boltzmann equation with hard potentials and diffuse reflection boundary condition of non-isothermal wall temperature of small variations around a positive constant, we construct a unique non-negative stationary solution

F

∗

, and further establish the dynamical stability of such stationary solution with exponential time decay rate. Due to the relativistic effect, the key point is to control the hydrodynamic part

P

f

by choosing suitable test functions, which are different from the ones of Esposito et al (2013 Commun. Math. Phys.
323 177–239).
Wasserstein convergence rates in the invariance principle for sequential dynamical systems
Authors: Liu Zhenxin , Wang Zhe
Published: November 2024

In this paper, we consider the convergence rate with respect to the Wasserstein distance in the invariance principle for sequential dynamical systems. We utilize and modify the techniques previously employed for stationary sequences to address our non-stationary case. Under certain assumptions, we can apply our result to a class of dynamical systems, including sequential β

n
-transformations, piecewise uniformly expanding maps with additive noise in one-dimensional and multidimensional case, and so on.
Modeling runaway electron losses due to tearing mode activities in HL-3
Authors: Zhang S L , Hao G Z , Liu Y Q , Dong G Q , Sun T F , Zhao Y F , Zhu Y X , Li Z J , Wang S , Wang Y Q , Zhang Y P , Liu L Z , Liang S Y , Yu L M , He Z Y H
Published: November 2024

Losses of runaway electrons (REs) due to magnetohydrodynamic (MHD) perturbations in a recent HL-3 discharge are numerically modeled by a linear stability code combined with a relativistic particle guiding-center orbit tracing module. The MHD perturbation is identified as (predominantly) the n = 1 (n is the toroidal mode number) tearing mode (TM) with large 3/1 and 2/1 Fourier components. The 2/1 islands are found significantly larger than the 3/1 counterpart. As the perturbation level associated with the TM progressively increases, the 3/1 island chains disappear and transition to the edge field stochasticity occurs at about 10 G field perturbation, according to the modeling. The tendency of RE losses, due to the three consecutive TM bursts observed in the experiment, is qualitatively captured by test particle tracing. Modeling finds about 0.7%, 3% and 25% RE loss fractions associated with these three bursts, assuming that the corresponding TM perturbation levels match that of the Mirnov data. High-energy REs are subject to less losses at low perturbation levels, due to the stronger inward shift of the particle orbits. Only full field line (or drift orbit) stochasticity facilitates losses of high-energy (

∼

10

MeV) REs.
Complex quadrupled-power-law nonlinearity form of Radhakrishnan-Kundu-Lakshmanan equation: novel optical soliton analysis
Authors: Tripathy A , Sahoo S , Sahu K M
Published: November 2024

In this manuscript, the novel optical wave solutions to the newly developed Radhakrishnan-Kundu-Lakshmanan (NRKL) model are studied. Two analytical methods namely, the new extended generalized Kudryashov and the extended modified auxiliary equation mapping methods are used to obtain these novel solutions. Furthermore, the dynamics of the obtained solutions are analyzed thoroughly with the help of different graphical forms such as three-dimensional (3-D), contour, and two-dimensional (2-D) figures. To get the graphical view of the derived solutions, numerical values for the unknown parameters are assigned while balancing the nonlinearity with dispersion. Moreover, the characteristics analysis of the obtained solutions depict anti-kink, periodic, bright, dark-shaped periodic, anti-bell shape, bright-shaped periodic, and dark waveforms Furthermore, the practical implications of these waveforms in optical fiber transmission are profound, with the potential to influence nonlinear signal processing and advanced optical network design.
On Some novel features of a Non-Hermitian multi-boson Hamiltonian : partial

P
T

-symmetry and ghosts
Authors: Chakraborty Arindam
Published: November 2024

The eigenvalues and eigenstates of a three-boson Hamiltonian are considered. The Hamiltonian is found to be pseudo-Hermitian in relation to its various partial PT-symmetries understood in a Fock space setting. The possibilities of symmetry adopting and symmetry breaking states are also discussed. Ghost states are found in relation to different symmetry induced inner-products. At least two of the ghost states show some kind of transition to normal states depending on the values of certain parameter.
Investigation of structural, morphological and optical characteristics of (Ni,Co)S/Fe3O4 nanocomposites and (Ni,Co)-doped Fe3O4 nanoparticles
Authors: Soltanpour P , Naderali R , Mabhouti Kh
Published: November 2024

The present search seeks to customize the optical, magnetic, and structural characteristics of NiS/Fe3O4 and CoS/Fe3O4 nanocomposites in contrast to Ni-doped Fe3O4 and Co-doped Fe3O4 nanoparticles to investigate linear, nonlinear, and optoelectronic applications. In this regard, the preparation of magnetite nanoparticles (Fe3O4) doped by Ni and Co and also NiS/Fe3O4 and CoS/Fe3O4 nanocomposites was successfully carried out through the co-precipitation method. The XRD obtained results revealed the presence of a face-centered cubic structure in all samples. Moreover, the estimation of the crystalline size for the Fe3O4, Ni-doped Fe3O4, Co-doped Fe3O4 NiS/Fe3O4, and CoS/Fe3O4 nanopowders was carried out using the Debye–Scherrer formula, yielding values ranging from 8.45 nm to 10.13 nm. Furthermore, nanopowder microstructure images were taken through a field emission scanning electron microscope (FESEM), which represented that the shape of the grains was spherical and irregular. Furthermore, the samples validate the purity of the samples which revealed the presence of vibrational modes in the metal oxide bonds. An optical investigation was conducted on all samples utilizing a diffuse reflectance spectroscopy. Band gap values ​​were estimated based on diffuse reflectance spectroscopy data through Tauc plot analysis, which yielded a range from 2.88 eV to 3.01 eV, indicating that the red shift in the band gap of Fe3O4 with all impurities except CoS/Fe3O4, provides catalytic applications of synthesized materials. Additionally, numerical calculations utilizing the Kramers-Kronig relation and Wemple-DiDomenico (WDD) model, were performed to assess the extinction coefficient (k), refractive index (n), linear susceptibility (

χ

1

), and third-order nonlinear susceptibility (

χ

3

) parameters on the reflectance data. Compared to other studied samples, the maximum evaluated values of

χ

3

and the density of polarizable constituents (N) were related to the Ni-doped Fe3O4 NPs. This observation suggests that the prepared nanopowders possess significant potential for utilization in both fields of linear and nonlinear optical devices.
Bounds on the charge of the graviton using gravitational wave observations
Authors: Nair S. , Vijaykumar A. , Sarkar S.
Published: November 2024

If the graviton possesses a non-zero charge qg
, gravitational waves (GW) originating from astrophysical sources would experience an additional time delay due to intergalactic magnetic fields. This would result in a modification of the phase evolution of the observed GW signal similar to the effect induced by a massive graviton. As a result, we can reinterpret the most recent upper limits on the graviton's mass as constraints on the joint mass-charge parameter space, finding |qg
|/e < 3 × 10-34 where e represents the charge of an electron. Additionally, we illustrate that a charged graviton would introduce a constant phase difference in the gravitational waves detected by two spatially separated GW detectors due to the Aharonov-Bohm effect. Using the non-observation of such a phase difference for the GW event GW190814, we establish a mass-independent constraint |qg
|/e < 2 × 10-26. To the best of our knowledge, our results constitute the first-ever bounds on the charge of the graviton. We also discuss various caveats involved in our measurements and prospects for strengthening these bounds with future GW observations.
Phase-matching enhanced quantum phase and amplitude estimation of a two-level system in a squeezed reservoir
Authors: Li 李 Yan-Ling 艳玲 , Liao 廖 Cai-Hong 彩红 , Xiao 肖 Xing 兴
Published: November 2024

Squeezed reservoir engineering is a powerful technique in quantum information that combines the features of squeezing and reservoir engineering to create and stabilize non-classical quantum states. In this paper, we focus on the previously neglected aspect of the impact of the squeezing phase on the precision of quantum phase and amplitude estimation based on a simple model of a two-level system (TLS) interacting with a squeezed reservoir. We derive the optimal squeezed phase-matching conditions for phase ϕ and amplitude θ parameters, which are crucial for enhancing the precision of quantum parameter estimation. The robustness of the squeezing-enhanced quantum Fisher information against departures from these conditions is examined, demonstrating that minor deviations from phase-matching can still result in remarkable precision of estimation. Additionally, we provide a geometric interpretation of the squeezed phase-matching conditions from the classical motion of a TLS on the Bloch sphere. Our research contributes to a deeper understanding of the operational requirements for employing squeezed reservoir engineering to advance quantum parameter estimation.
Established conversions for hybrid entangled states assisted by error-predicted parity-discriminated devices
Authors: Du 杜 Fang-Fang 芳芳 , Fan 范 Zhi-Guo 志国 , Ren 任 Xue-Mei 雪梅 , Ma 马 Ming 明 , Liu 刘 Wen-Yao 文耀
Published: November 2024

Hybrid entangled states are crucial in quantum physics, offering significant benefits for hybrid quantum communication and quantum computation, and then the conversion of hybrid entangled states is equally critical. This paper presents two novel schemes, that is, one converts the two-qubit hybrid Knill–Laflamme–Milburn (KLM) entangled state into Bell states and the other one transforms the three-qubit hybrid KLM state into Greenberger–Horne–Zeilinger (GHZ) states assisted by error-predicted and parity-discriminated devices. Importantly, the integration of single photon detectors into the parity-discriminated device enhances predictive capabilities, mitigates potential failures, and facilitates seamless interaction between the nitrogen-vacancy center and photons, so the two protocols operate in an error-predicted way, improving the experimental feasibility. Additionally, our schemes demonstrate robust fidelities (close to 1) and efficiencies, indicating their feasibility with existing technology.
Topological states constructed by two different trivial quantum wires
Authors: Lin 林 Jing-Run 景润 , Lv 吕 Linxi 林喜 , Zuo 左 Zheng-Wei 正伟
Published: November 2024

The topological states of the two-leg and three-leg ladders formed by two trivial quantum wires with different lattice constants are theoretically investigated. Firstly, we take two trivial quantum wires with a lattice constant ratio of 1:2 as an example. For the symmetric nearest-neighbor intra-chain hopping two-leg ladder, the inversion symmetry protected topological insulator phase with two degenerate topological edge states appears. When the inversion symmetry is broken, the topological insulators with one or two topological edge states of different energies and topological metals with edge states embedded in the bulk states could emerge depending on the filling factor. The topological origin of these topological states in the two-leg ladders is the topological properties of the Chern insulators and Chern metals. According to the arrangement of two trivial quantum wires, we construct two types of three-leg ladders. Each type of the three-leg ladder could be divided into one trivial subspace and one topological nontrivial subspace by unitary transformation. The topological nontrivial subspace corresponds to the effective two-leg ladder model. As the filling factor changes, the system could be in topological insulators or topological metals phases. When the two-leg ladder is constructed by two trivial quantum wires with a lattice constant ratio of 1:3 and 2:3, the system could also realize rich topological states such as the topological insulators and topological metals with the topological edge states. These rich topological states in the two-leg and three-leg ladders could be confirmed by current experimental techniques.
The effect of overhang and recoater angles on the quality of laser powder bed fusion produced parts with contactless supports
Authors: Gülcan Orhan , Günaydın Kadir , Tamer Aykut
Published: November 2024

This experimental study focuses on the effect of overhang and recoater angles on the surface roughness of overhang specimens produced by laser powder bed fusion (LPBF) process from CoCr material and by using contactless support structures. The inclination of overhang surface with respect to build platform and the orientation of the specimens with respect to recoater direction were selected as design inputs and the average and the maximum surface roughness of overhang surfaces were selected as design outputs. Experimental studies revealed that decreasing overhang angle increased the surface roughness. 90-degree orientation of the part with respect to recoater direction resulted in minimum average surface roughness. It was also observed that contactless support didn’t give enough structural strength to 20-degree overhang surface which failed to be manufactured. Thermomechanical modelling-based process simulations were also performed, and very good correlation was found between numerical and experimental results. It was shown that thermomechanical modelling is very useful to be performed before LPBF process to mitigate recoater jam risks.
Coal gangue based geopolymer as an additive of warm mix asphalt: preparation and properties
Authors: Tang Ning , Nie Nan , Du Wenjie , Sun Yihan , Li Ruxun , Zhang Ruofei
Published: November 2024

In contrast to conventional hot mix asphalt technology (HMA), warm mix asphalt technology (WMA) permits the mixing and compaction of asphalt mixture at lower temperatures. This innovative approach is characterized by significant energy savings and reduced emissions, making it a sustainable choice for asphalt mixture production. This paper used coal gangue to prepare a WMA additive. By leveraging the free water in its zeolite-like structure, which evaporates upon heating, bubbles form within the bitumen. This causes bitumen to expand and lose viscosity, thereby achieving the purpose of warm mixing. Both achieve a decline in the asphalt mixture’s mixing temperature and provide an effective method for utilizing coal gangue resources. It helps mitigate the environmental hazards associated with the massive accumulation of coal gangue, including soil contamination and water resource pollution. Therefore, based on alkali activation theory, this paper aimed to develop a novel coal gangue geopolymer (CG) WMA additive. CG was characterized through microscopic testing and analysis of water storage stability. The impact of varying CG dosages on the conventional performance of bitumen was examined. The bitumen foaming test elucidated the warm mixing mechanism and foaming behavior of the CG. Additionally, the road performance of the WMA was analyzed. The findings indicate that CG has abundant pore structures, providing an effective water storage space, and CG as a WMA additive exhibits good water storage stability at ambient temperature. When the CG dosage is 5% by the mass of bitumen, the viscosity of bitumen at 130∼140 °C is appropriate, and the WMA results in good road performance. Compared with HMA, the mixing temperature is reduced by a range of 20∼50 °C.
Experimental investigation on electrochemical discharge machining of hastelloy
Authors: Karthik Kanulla , R Ranjith , Veduru Venkatrami Reddy , Nallasivam Kawin
Published: November 2024

The study examines the influence of various process parameters on Material Removal Rate (MRR), Tool Wear Rate (TWR) AND Surface Roughness (Ra) during the machining of Hastelloy using Electrical Discharge Machining (EDM) machined under NaOH dielectric medium. Results showed that a 20% NaOH concentration optimizes MRR at 0.889 mm3 min−1, while higher concentrations lead to process instability due to excessive bubble formation and discharge irregularities. The optimal current of 30 A improves MRR, but excessive melting occurs beyond this level, negatively impacting tool wear and surface finish. A pulse-on time of 45 μs produces the best surface finish of 1.786 μm), while longer pulse durations cause overheating and degrade surface quality. TWR was minimized at a gap distance of 2 mm, which allowed effective cooling and debris removal, reducing wear by 15%. Voltage levels between 12 V and 18 V resulted in the most stable discharges, yielding optimal MRR and Ra values. Lower current values stabilize TWR, while higher currents and longer pulse-on times increase wear. A gap distance of 2 mm minimizes TWR by ensuring effective cooling and debris removal. Optimal surface roughness is achieved with 30 A and 45 μs, where controlled discharges reduce surface imperfections. Higher NaOH concentrations induce rougher textures due to more aggressive sparks. SEM analysis confirms that process parameters significantly impact surface topography, characterized by craters, re-solidified debris, and microcracks. The optimized parameters identified from the results were 20% NaOH concentration, 30 A current, 45 μs pulse-on time, 2 mm gap distance, and voltage of 15 V.
The nexus between CO2 emissions, renewable energy consumption, foreign direct investment, and economic growth: Evidence across different income groups of countries
Authors: Andrei Jean Vasile , Armeanu Daniel Ștefan , Gherghina Ştefan Cristian , Joldeș Camelia Cătălina
Published: November 2024

This study examines the possible dynamic link among economic growth, renewable energy consumption, environmental emissions, and CO2 across various countries from 2000 to 2019. By categorizing countries based on income levels, the research aims to examine the interactions among variables such as CO2 emissions, foreign direct investments (FDI), labor force, industrial value-added, and gross capital formation. Employing a quantitative approach, several statistical methods were applied, including panel unit root examination, Pedroni cointegration analysis, VECM models (Vector Error Correction Model), and panel causality testing. Evidence of cointegration among the variables was found. The causality test showed causal relationships between the variables. The results underscore the intricate relationships between energy consumption, environmental factors, and economic development. The study underscores that while renewable energy is vital for sustainable development, its impact on economic growth is influenced by various factors and policies.
Vertical flow constructed wetlands efficiency with varying surface loading rates
Authors: Aljaddou Heba , Alsaeed Ruba Dahham , Fatamah Mohamad
Published: November 2024

This paper searches in determining the optimal surface loading rates of constructed wetland treatment plant with vertical flow, through constructing a pilot plant which is consist of two filters, the first one is planted with Phragmites plant while the other is unplanted. As a result, it is recommended that constructed wetlands in our country should be designed with consideration of applying low surface loading rate (at least 1 m2 p−1). The removal efficiencies observed for Chemical Oxygen Demand (COD), Suspended Solids (SS), Total Nitrogen (TN), and Phosphate (PO4) were notably enhanced in the presence of vegetation, with improvements reaching up to 14%, 10%, 11%, and 12% respectively across various applied surface loading rates.
Graph-based feature engineering for enhanced machine learning in rolling element bearing fault diagnosis
Authors: Hosseini Seyed Mohammad , Dibaji Abolfazl , Sulaimany Sadegh
Published: November 2024

Fault diagnosis in rolling element bearings is critical for ensuring machinery reliability. This study improves machine learning techniques for predictive fault detection using the benchmark CWRU bearing dataset. Vibration signal data is preprocessed via balancing and graph-based feature engineering is performed to enable effective model training. Diverse classifiers including Random Forests, Support Vector Machines and Neural Networks are systematically evaluated through 10-fold cross-validation. Most of the models demonstrate exceptional performance, with top accuracies and AUC scores of 1.00. The research highlights the potential of hidden features that consider the implicit relations between the entities to improve predictive maintenance through data-driven bearing fault diagnosis.
Climate change, mass casualty incidents, and emergency response in the Arctic
Authors: Malik Ishfaq Hussain , Ford James D , Clark Dylan G , Pearce Tristan
Published: November 2024

Acute emergencies have been neglected in efforts to understand and respond to the transformational climatic changes underway in the Arctic. Across the circumpolar north, social-technological changes, extreme weather, and changing ice conditions threaten lives and infrastructure, increasing the risk of mass casualty incidents (MCIs), particularly as they impact transportation systems including global shipping, aviation, and community use of semi-permanent trails on the ice, land, and water. The Arctic is an inherently dangerous environment to operate in, and due to living in permanent settlements and the uptake of mechanised modes of transportation and navigation technologies, people’s exposure to risks has changed. In responding to potential MCIs, emergency response systems face challenges due to remoteness, weather, and changing environmental conditions. We examine emergency response capacity in the Arctic, focusing on search and rescue and using examples from Canada and Greenland, identifying opportunities for enhancing emergency response as part of climate adaptation efforts.
Understanding solar minigrid sustainability and impact through a holistic key performance indicator framework
Authors: Eales Aran , Banda Elizabeth , Frame Damien , Strachan Scott
Published: November 2024

Despite increasing global electrification rates, over 700 million people remain without access to electricity, predominantly in Sub-Saharan Africa. Solar minigrids offer a promising solution for rural electrification in areas unlikely to be connected to the national grid. However, existing evaluations of minigrid projects often overlook holistic performance, particularly the social impacts on the communities they serve. This study aims to fill this gap by proposing a novel key performance indicator (KPI) framework that integrates technical, economic, and social metrics, providing a comprehensive assessment of minigrid performance. The research question guiding this study is: How can a holistic KPI framework enhance the understanding of solar minigrid sustainability and impact? To address this, KPIs were designed through a systematic process involving a literature review, stakeholder engagement, and validation through a case study minigrid in Malawi. The framework was applied using data collected from smart meters, remote monitoring, and enumerator surveys. Key findings reveal that while technical performance was robust, economic sustainability requires further optimisation, and social impacts, particularly on gender and community well-being, were significant. This study demonstrates the importance of a balanced evaluation framework that considers all dimensions of minigrid performance. By adopting such a holistic approach, minigrid developers, policymakers, and investors can make more informed decisions, ultimately improving the sustainability and effectiveness of rural electrification projects.