bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental investigation on enhancing oil recovery of volcanic fractured oil reservoir by gas injection huff-n-puff considering gas diffusion
Authors: Yao Chuanjin , Chen Nan , Liu Baishuo , Liu Yaqian , Xuan Yangyang , Yang Huichao
Published: December 2024

The pore structure of volcanic fractured oil reservoirs is complicated, and the traditional gas displacement and waterflooding are not ideal. In this paper, the pore structure characteristics of volcanic rock were analyzed. Then, the diffusion procedure of CO2 and natural gas in saturated oil porous media was analyzed by pressure drop method. Finally, huff-n-puff experiments of CO2 and natural gas were conducted to analyze factors on the recovery factor (RF), and the oil mobilization pattern was quantitatively characterized. By huff-n-puff, we mean injecting gas from one end and then soaking it for a period of time before producing oil, utilizing pressure-driven and physicochemical reactions to affect the oil. The results show that the pore size distribution range is large. The diffusion of CO2 and natural gas can be divided into three stages: rapid diffusion, slow diffusion and equilibrium, and the diffusion coefficient of CO2 is 10 times that of natural gas under same condition. Compared with vertical fractures and horizontal fractures, reticulate fractures have more influence on gas diffusion coefficient. After 6 cycles, the RF of CO2 is 15% higher than that of natural gas, and the contribution of the first 4 cycles to the RF is 91.38%. In addition, CO2 huff-n-puff primarily mobilizes oil in medium (0.1 μm < r < 1 μm) and large (r > 1 μm) pores. These research results can provide a good theoretical guidance for the efficient development of VFOR and CO2 sequestration.
Modeling and application research of absolute gravimeter driven by a V-shaped linear ultrasonic motor
Authors: Zhou Lifeng , Xu Hao , Geng Ranran , Yao Zhiyuan
Published: December 2024

A V-shaped linear ultrasonic motor (LUSM), used as a driving element for the absolute gravimeter, generates structural vibrations when the motor starts and stops, which interfere with and influence the accurate measurement of the absolute gravimeter. In order to address this problem and provide better stability and measurement accuracy, this paper designs a fuzzy proportional integral differential (PID) controller and realizes the drive control of the motor on a field programmable gate array (FPGA) using the Verilog hardware description language (HDL). The advantages of the proposed controller are verified by comparing the simulation results with those of the traditional PID controller. First, the technical index of the LUSM as the driving element is studied through theoretical analysis based on the operation mechanism of the absolute gravimeter. Then, the relationship between the output performance and the input parameters (excitation voltage, preload, and driving frequency) of the motor in a vacuum/natural environment is experimentally investigated. Finally, an experimental system is constructed, and experiments are conducted to measure the acceleration of gravity and compare with the test results of the habitual FG-5 absolute gravimeter. The experimental results show that the output performance of the V-shaped LUSM meets the requirements of the driving element of the absolute gravimeter. The combination of the two control methods can realize the repeatable and stable operation of the system. Moreover, the motor with a mass of only 92 g can output force directly without transmission components. The complexity and the weight of the system are significantly reduced, which has certain advantages.
Influence of sweep angle on leading edge vortex dynamics of a fully passive oscillating-plate hydrokinetic turbine prototype
Authors: Lee Waltfred , Dumas Guy , Oshkai Peter
Published: December 2024

The present work assesses the use of spanwise flow in enhancing the performance of the fully passive oscillating-plate hydrokinetic turbine prototype by relating the dynamics of the leading edge vortex (LEV) to the power extraction performance. Two-dimensional (2D) planar and three-dimensional (3D) tomographic particle image velocimetry were employed to obtain quantitative flow structure of oscillating-plates undergoing heave and pitch motion in uniform inflow at Reynolds number of 21 000. A plate with a 6° sweep angle and an unswept plate (control case) were considered in the present study. Dynamics of the LEV were investigated using the patterns of the phase-averaged vorticity during the oscillation cycle. The 3D vector fields provided insights into the spanwise variation of the vortical structure and the rate of deformation of the vortex, which was determined by calculating the deformation terms in the vorticity transport equations which are related to the stability of the vortex. The results show evidence of a delay in the shedding of the LEV and an increase in its stability in the case of the swept plate, compared to the control case, which in turn benefit the power extraction performance at high inflow velocities.
Exploring direct photodetachment and photodissociation–photodetachment dynamics of platinum iodide anions (PtIn−, n = 2–5) using cryogenic photoelectron spectroscopy
Authors: Zhao Qixu , Zhang Jian , Li Xueying , Tang Peng , Yang Fan , Ma Junyang , Hu Zhubin , Sun Haitao , Wang Xue-Bin , Sun Zhenrong , Yang Yan
Published: December 2024

The direct photodetachment and two-photon photodissociation–photodetachment processes of a series of PtIn− (n = 2–5) anions were systematically studied using cryogenic anion photoelectron spectroscopy and first-principles electronic structure calculations. The adiabatic/vertical detachment energies (ADEs/VDEs) of these anions were determined from their 193 nm photoelectron (PE) spectra, i.e., 3.54/3.63, 4.04/4.09, 4.33/4.36, and 4.37/4.41 eV for n = 2–5, respectively, and well reproduced by B3LYP-D3(BJ)/aug-cc-pVTZ-pp calculations. As the coordination number increases, the electron affinity (EA) of PtIn• (n = 2–5) neutrals (equivalent to the corresponding anion’s ADE) gradually increases, exceeding the EA of Cl at n = 3 and exhibiting superhalogen characteristics for n ≥ 3. Meanwhile, the ground state transition contributed from detaching electrons in the highest occupied molecular orbital gradually evolves from the central metal Pt to the iodine ligands. For the PtI3− anion, besides one-photon direct detachment, four distinct two-photon photodissociation–photodetachment channels were identified, and the competition between them was discussed.
Chasing Schottky–Mott: Metal-first non-alloyed contacts to β-Ga2O3 for interface quality and minimal surface modification
Authors: Smith Kathleen T. , Gorsak Cameron A. , Buontempo Joshua T. , Cromer Bennett J. , Ikenoue Takumi , Gulupalli Hemant , Thompson Michael O. , Jena Debdeep , Nair Hari P. , Xing Huili Grace
Published: December 2024

Metal-first non-alloyed ohmic and Schottky contacts are fabricated on β-Ga2O3 with a range of metal work functions (ϕM). The resulting ohmic contacts are of high quality with a contact resistance (Rc) as low as 0.069 ± 0.003 Ω mm. Measurements of the barrier heights (ϕB) indicate that metal-first processing, which preserves the as-grown/bare-substrate surface, also partially un-pins the Fermi-level in (010) and (2¯01) oriented Ga2O3. Depth-resolved XPS (x-ray photoelectron spectroscopy) measurements of the oxidation state throughout the contact metal at the contact–Ga2O3 interface indicate that most non-alloyed contact metals are at least partially oxidized by room temperature redox reactions with the underlying Ga2O3, with metals with a lower ϕM also demonstrating the greatest level of oxidation. As oxidation has been previously observed to enhance a metal’s work function, this may imply that to-date observations of indices of surface behavior << 1 on β-Ga2O3, which have been attributed to severe Fermi-level pinning, may need to be corrected to account for this partial oxidation in addition to other surface modifications during device processing demonstrated in this work.
Effect of leading edge tubercles bionic blade of high speed pump jet propulsor on cavitation suppression
Authors: Li Huairui , Gan Gongchang , Duan Yuchen , Zhu Rongsheng , Fu Qiang
Published: December 2024

The occurrence of cavitation in hydraulic machinery is a matter of significant concern, as it presents a substantial risk to the reliable functioning of pump jet propulsors. The point of this study is to find out how well bionic blades with different kinds of leading edge (LE) tubercles distribution stop cavitation in high-speed pump jet propulsors. Furthermore, it examines their performance in various cavitation scenarios. The study conducts a thorough evaluation of the function of bionic blades in mitigating cavitation and maintaining performance by analyzing head, efficiency, cavitation shape, pressure distribution, entropy production, vortex flow, and pressure pulsations. In the absence of reaching the cavitation critical point, the bionic blade 1 (BB1) model exhibited a head that was 2.65% greater than that of the original blade (OB) model. Additionally, it had the highest level of effectiveness among the three bionic blades in preventing cavitation, causing a 5%–8% delay. Furthermore, the LE tubercles not only successfully inhibited cavitation but to some degree stimulated the formation of both tip clearance cavitation and tip leakage cavitation. The BB1 model did a better job of controlling entropy production and vortex flow during the inception to collapse of cavitation. This led to lower losses, more consistent flow properties, and higher efficiency compared to the OB model. Analysis of the pressure pulsations shows that BB1 exhibits a reduction in pulsation intensity across all cavitation numbers, indicating excellent dynamic stability.
Interplay between classical and quantum dissipation in light–matter dynamics
Authors: Tarasi Facundo , Todorov Tchavdar N. , Bustamante Carlos M. , Gadea Esteban D. , Stella Lorenzo , Apostolova Tzveta , Scherlis Damián A.
Published: December 2024

A quantum-electrodynamics approach is presented to describe the dynamics of electrons that exchange energy with both photon and phonon baths. Our ansatz is a dissipative quantum Liouville equation, cast in the Redfield form, with two driving terms associated with radiative and vibrational relaxation mechanisms, respectively. Remarkably, within the radiative contribution, there is a term that exactly replicates the expression derived from a semiclassical treatment where the power dissipated by the electronic density is treated as the emission from a classical dipole [Bustamante et al., Phys. Rev. Lett. 126, 087401 (2021)]. Analysis of the distinct contributions to the total radiation shows that the semiclassical emission depends on the coherences, with the remainder of the quantum-electrodynamics driving term determined by the excited populations, thus accounting for the relaxation of eigenstates or incoherent mixed states. This approach is used to investigate the response of the Su–Schrieffer–Heeger model for trans-polyacetylene to both pulsed and continuous laser irradiation. Upon excitation with a short pulse and in the absence of the vibrational mechanism, the conducting band population exhibits a stepwise relaxation, characterized by cycles of exponential decay followed by a transient subradiant state. The latter arises from the collective coupling between Bloch states featuring a quasi-continuum energy spectrum in reciprocal space. The separate examination of the semiclassical dynamics reveals that it is this contribution that is responsible for the collective behavior. If vibrational dissipation is active, following the laser pulse, the excited electrons rapidly populate the minimum of the conduction band, and the emission spectrum shifts to lower frequencies with respect to absorption. Meanwhile, continuous irradiation drives the system to a stationary state with a broad emission spectrum.
Multiscale modeling of short pulse laser induced amorphization of silicon
Authors: He Miao , Zhigilei Leonid V.
Published: December 2024

Silicon surface amorphization by short pulse laser irradiation is a phenomenon of high importance for device manufacturing and surface functionalization. To provide insights into the processes responsible for laser-induced amorphization, a multiscale computational study combining atomistic molecular dynamics simulations of nonequilibrium phase transformations with continuum-level modeling of laser-induced melting and resolidification is performed. Atomistic modeling provides the temperature dependence of the melting/solidification front velocity, predicts the conditions for the transformation of the undercooled liquid to the amorphous state, and enables the parametrization of the continuum model. Continuum modeling, performed for laser pulse durations from 30 ps to 1.5 ns, beam diameters from 5 to 70 μm, and wavelengths of 532, 355, and 1064 nm, reveals the existence of two threshold fluences for the generation and disappearance of an amorphous surface region, with the kinetically stable amorphous phase generated at fluences between the lower and upper thresholds. The existence of the two threshold fluences defines the spatial distribution of the amorphous phase within the laser spot irradiated by a pulse with a Gaussian spatial profile. Depending on the irradiation conditions, the formation of a central amorphous spot, an amorphous ring pattern, and the complete recovery of the crystalline structure are predicted in the simulations. The decrease in the pulse duration or spot diameter leads to an accelerated cooling at the crystal–liquid interface and contributes to the broadening of the range of fluences that produce the amorphous region at the center of the laser spot. The dependence of the amorphization conditions on laser fluence, pulse duration, wavelength, and spot diameter, revealed in the simulations, provides guidance for the development of new applications based on controlled, spatially resolved amorphization of the silicon surface.
The blockage and erosion characteristics of woody debris flow on an erodible gully bed: Insight from a small-scale model experiment
Authors: Yang Huaquan , Liu Jinfeng , Sun Hao , Zhang Wentao , Shang Yuqi , Fu Hang
Published: December 2024

During the transportation process of debris flow with large wood (LW), phenomena such as channel blockage and collapse frequently occurs, resulting in increased discharge surges, heightened erosion intensity, and amplified damage. Accurately predicted the blockage performance is the basis of evaluating the damage and disaster mitigation of woody debris flow. In this study, we conducted a series of laboratory experiments of woody debris flow on erodible gully bed. The experiment results show that the final blockage types can be divided into three types: non-blockage, blockage, and semi-blockage. Temporary blockage will cause abundant sediment deposited temporarily and then released instantaneously, resulting in destructive surges and eventually lead to semi-blockage and non-blockage. The blockage degree is positively correlated with the relative length, relative content of LW, and bulk density of debris flow, but negatively correlated with slope. Channel blockage is often accompanied by significant local erosion effect, and the erosion depth of downstream channel increases with the increase in blockage degree. The blockage and collapse mechanism of woody debris flow was analyzed, and the results emphasized that channel erosion promoted the outbreak of blockage collapse. Based on the analysis of blockage performance, we propose an improved blockage criterion F to evaluate the blockage degree, and the high probability range of temporary blockage is determined as 1.5–5.0. The results can provide reference for the risk assessment and mitigation of woody debris flow.
Flow dynamics and theoretical modeling of monolayer ionic solutions confined within Ångstrom-scale channels
Authors: Wang Qiyuan , Zhou Runfeng , Sun Chengzhen
Published: December 2024

Comprehending the flow dynamics of ionic solutions within nanoconfined spaces is imperative for diverse applications encompassing desalination, nanofiltration, energy storage, and electrochemical devices. When the confinement space is further reduced to 1 nm (Ångstrom scale), monolayer ionic solutions will emerge. In this regime, ions not only have the ability to influence water properties such as viscosity but also primarily modify the interactions and corresponding slip length (or friction coefficient) between the solution and wall. Notably, ion effects on water flow dynamics at Ångstrom scale exhibit unique characteristics compared to those at nanoscale and macroscale levels. In this study, we investigate the pressure-driven transport of monolayer ionic solution confined within two-dimensional graphene channels and explore the influences of ionic type, concentration, and valency on the flow rate of water via molecular dynamic simulations. Our findings reveal that divalent ions (e.g., Mg2+ and Ca2+) considerably reduce water flow rates due to enhanced viscosity and fluid–solid interface interaction compared to monovalent ions (e.g., Na+ and K+). Subsequently, we develop a theoretical model based on the Hagen–Poiseuille (HP) equation that incorporates modifications for ion-specific viscosity and slip length at the Ångstrom-scale level. By incorporating self-calculated values for water viscosity and friction coefficient/slip length at the graphene–water interface into our modified HP equation, water flow rate is basically predicted while emphasizing the critical role of ion–water interactions in Ångstrom-scale fluid transport.
Instability and collapse mechanisms of O2 and N2 nanobubble gas–liquid interfaces: A molecular dynamics simulation study
Authors: Zhang Xuesong , Fan Zhenzhong , Cai Li , Fu Yuanfeng , Liu Jingang , Tong Qilei , Qiao Sanyuan , Sun Ao
Published: December 2024

Nanobubbles, with their stability and oxidative properties, are widely applied in biomedicine, flotation, and environmental remediation. While experimental studies have explored their application effects, the dynamic behavioral characteristics of gas-containing nanobubbles during collapse remain insufficiently investigated. This study employs molecular dynamics simulation to examine nanobubble collapse under various conditions, including impact velocities, gas types, bubble sizes, and gas densities. Results show that increasing bubble size expands the microjet radiation area, while higher impact velocities increase microjet velocities. Gas types affect the jet radiation area due to differences in van der Waals forces and solubility. Vacuum nanobubbles exhibit higher maximum jet velocities than nitrogen and oxygen nanobubbles. Gas cushioning and compression rebound significantly influence maximum jet velocity. Microjets induce vortex structures, gas surface changes, and local pressure increases, leading to secondary water hammer impacts. Simulation results align well with theoretical calculations. This study provides the theoretical foundation for the industrial-scale implementation of nanobubble cavitation technology.
Dynamic analysis of natural supercavitating flow during acceleration and deceleration of an axis-symmetric projectile
Authors: Xu Chang , Khoo Boo Cheong , Cui Yongdong
Published: December 2024

Supercavitation is an effective drag reduction technology for high-speed underwater vehicles. However, the evolution of supercavitating flow becomes more complex during acceleration and deceleration compared to steady-state conditions. This paper examines the unsteady supercavitating flow around an axis-symmetric projectile with disk cavitation subjected to various speed transitions. By utilizing the volume of fluid method, the large eddy simulation turbulence model, and the Kunz cavitation model, the study simulates and validates the dynamic behavior of the multiphase flow against experimental and published data. The cavity evolution during acceleration and deceleration is observed in three distinct stages. In the case of acceleration, the stages include initial stabilization, merging of the leading edge and shoulder cavities, and full supercavitation. For deceleration, the stages involve cavity collapse, trailing-edge cavity separation, and shoulder cavity formation. The study also highlights the presence of cavitation hysteresis, especially at higher acceleration and deceleration rates, which influences flow stability and drag reduction. This research provides insights for optimizing the design and control of high-speed underwater vehicles, where stable cavity formation is crucial for minimizing drag. Understanding how acceleration and deceleration influence cavity evolution can guide the refinement of cavitation designs and control strategies, improving vehicle performance during dynamic maneuvers.
Preparation of temperature-stable 0.8MgTiO3–0.2Mg2SiO4–0.06CaTiO3 microwave dielectric ceramics for unilateral radiating dielectric resonator antenna without ground plane
Authors: Du Chao , Wang Zhiji , Chen Hetuo , Zhou Guohong , Wang Shaofei , Xia Song , Zhou Di
Published: December 2024

Unilateral radiating antennas are widely studied due to their ability to provide lateral or unidirectional radiation patterns, which are especially suitable for indoor and office Wi-Fi router applications. In this letter, a unilateral radiating rectangular dielectric resonator antenna (DRA) without a ground plane is proposed. A temperature stable low-loss 0.8MgTiO3–0.2Mg2SiO4–0.06CaTiO3 (MT–MS–CT) composite ceramic prepared via solid-state reaction and sintered at 1380 °C is utilized for the proposed DRA. Notably, the MT–MS–CT composite ceramic shows good dielectric performance with a permittivity of εr∼13, a quality factor of Q×f0∼115,000, Q = 1/dielectric loss, f0 = 8.6 GHz, and a temperature coefficient of resonant frequency TCF∼+4.6ppm/°C. Its unilateral radiation pattern is based on the complementary magnetic dipole and electric dipole, where the excited dominant TE111 mode of the rectangular DRA serves as the magnetic dipole and a probe acts as an electric dipole. The proposed prototype antenna fabricated using the composite ceramic has a unilateral radiation pattern with wide impedance bandwidth, reasonable gain, and radiation efficiency of 95%.
Simulations on perturbation growth and mixing of a shocked light fluid layer with two different interfaces
Authors: Zheng Dugang , Guo Xu , Zhai Zhigang , Luo Xisheng
Published: December 2024

The Richtmyer–Meshkov instability of a light fluid layer with two different interface modes is studied numerically. By fixing the wavelength of the second interface (I2) while varying that of the first interface (I1), we examine distinct cases with identical wavelengths at both interfaces, as well as smaller or larger wavelengths at I1, to explore the effects of initial layer configurations on instability development. The larger wavelength interface significantly transmits modes to the smaller wavelength interface, whereas mode transmission in the reverse direction is limited. This results in two primary consequences: (i) the smaller wavelength interface and the overall mixing layer evolve periodically with the larger wavelength; (ii) compared to the identical wavelength case, the linear amplitude growth duration of I2 is slightly extended for the smaller I1 wavelength case, but significantly prolonged for the larger I1 wavelength case. The linear amplitude growth rate of I2 for all cases can be predicted by the model of Jacobs et al. [J. Fluid Mech., vol. 195, 23–42 (1995)]. For cases with identical wavelengths and larger I1 wavelengths, the collisions of finger structures at both interfaces occur earlier, suppressing the growth of mixing width at early times while enhancing the mixed mass. In the later stages, the overall mixing efficiency in these cases significantly declines, despite continuous increases in both mixing width and mixed mass. This decline is attributed to severe deformation of the mixing layer due to interactions between finger structures, confining intense mixing to localized regions.
A novel vortex heat flowmeter for redox flow batteries enables flow monitoring and control
Authors: Yu Menglin , Wan Jianfeng , Bi Wenyan , Li Tianen , Sun Yihong , Xie Shizheng , Liu Baozhong
Published: December 2024

Redox flow batteries are widely used in energy storage. There is an urgent need for a flow meter that can control the electrolyte flow. In this Letter, we designed a novel vortex heat flowmeter. Vortex flow is generated by a square cavity. This novel flowmeter exhibits two typical flow structures at different heating temperature differences (ΔT). The phenomenon is the influence of thermal buoyancy. A vortex heat flowmeter with good linearity can be developed. When ΔT increases, a micro-valve flow structure can control the opening degree and thus the flow rate. The distinction between the two is assessed: ΔT=3.58V−5.94.
Adjustable enhanced photoluminescence in whispering-gallery-mode microdisk arrays
Authors: Yan Jia , Zhang Zhifang , Huang Qiang , Zhan Yan , Yang Jingpu , Luo Wei , Jiang Zuimin , Zhong Zhenyang
Published: December 2024

Microdisk with whispering gallery modes (WGMs) is a prominent candidate for the studies of fundamental properties of cavity quantum electrodynamics (CQED) and the explorations of on-chip light sources or sensors. Here, we report on the significant array effect on WGMs in SiGe microdisk arrays. Systematic photoluminescence spectra demonstrate an optimal microdisk interval associated with wavelength and the array symmetry dependence for each WGM. The enhancement factor of WGM can be increased by over 270% and 120% with the modification of microdisk interval and array symmetry, respectively. Moreover, a single dominant WGM can be achieved in the array of microdisks with intentionally designed nanoholes. The intrinsic mechanism of the array effect is disclosed in terms of the intradisk light field distribution and the interdisk coupling. Our results provide strategies for the substantial enhancement of desired WGM in microdisk array to comprehensively understand CQED and fabricate innovative optoelectronic devices.
The kinetochore protein KNL-1 regulates the actin cytoskeleton to control dendrite branching
Authors: Alves Domingos Henrique , Green Mattie , Ouzounidis Vasileios R. , Finlayson Cameron , Prevo Bram , Cheerambathur Dhanya K.
Published: December 2024

The function of the nervous system is intimately tied to its complex and highly interconnected architecture. Precise control of dendritic branching in individual neurons is central to building the complex structure of the nervous system. Here, we show that the kinetochore protein KNL-1 and its associated KMN (Knl1/Mis12/Ndc80 complex) network partners, typically known for their role in chromosome-microtubule coupling during mitosis, control dendrite branching in the Caenorhabditis elegans mechanosensory PVD neuron. KNL-1 restrains excess dendritic branching and promotes contact-dependent repulsion events, ensuring robust sensory behavior and preventing premature neurodegeneration. Unexpectedly, KNL-1 loss resulted in significant alterations of the actin cytoskeleton alongside changes in microtubule dynamics within dendrites. We show that KNL-1 modulates F-actin dynamics to generate proper dendrite architecture and that its N-terminus can initiate F-actin assembly. These findings reveal that the postmitotic neuronal KMN network acts to shape the developing nervous system by regulating the actin cytoskeleton and provide new insight into the mechanisms controlling dendrite architecture.
Stability for a multi-frequency inverse random source problem
Authors: Wang Tianjiao , Xu Xiang , Zhao Yue
Published: December 2024

We present increasing stability estimates for the inverse random source problem of the Helmholtz equation in two and three dimensions by multi-frequency near-field data. The random source is assumed to be a microlocally isotropic generalized Gaussian random function such that its covariance is a classical pseudodifferential operator. We consider the use of either expectation of the correlation data or the data obtained from a single realization of the random source. For the direct problem, by exploring the regularity of the Green function, we demonstrate that the direct problem admits a unique bounded solution with an explicit integral representation. For the inverse problem, the analysis employs microlocal analysis to derive an estimate for the Fourier transform of the micro-correlation strength by the near-field correlation data and a high-frequency tail. The stability is achieved by showing the analyticity of the data and applying a novel analytic continuation principle. Furthermore, with the help of ergodicity, the stability estimate can be extended to the case of using only a single realization of the data. The stability estimates have a unified form which consists of the Lipschitz type data discrepancy and the logarithmic stability. The latter decreases as the upper bound of the frequency increases, which exhibits the phenomenon of increasing stability.
Gas-compensated thermal flow sensor using an integrated velocity-independent gas properties meter
Authors: Azadi Kenari S , Wiegerink R J , Sanders R G P , Lötters J C
Published: December 2024

A gas-compensated thermal flow sensor is presented that measures the flow rate in real-time, independent of the type of gas, by simultaneously measuring and compensating for the thermal conductivity and volumetric heat capacity of the gas. The thermal flow sensor consists of two free-hanging, heated wires, forming a calorimetric flow meter. The temperature difference between the two wires is a function of the flow rate and the fluid thermal properties. An additional heated wire is integrated on the same chip and used to measure the gas properties. This wire is suspended over a shallow V-groove cavity, and oriented perpendicular to the flow direction, so that it is only affected by the gas properties and not by the flow. DC excitation is used to measure the thermal conductivity, and AC excitation with the 3ω method is used to determine the volumetric heat capacity. The output of the thermal flow sensor is automatically corrected for the medium using these measured parameters. Measurements were performed with 11 different gases and gas mixtures, and in all cases the deviation between the applied flow rate and measured flow rate is less than 10%.
A multimass velocity-map and covariance-map imaging study of the dissociative electron ionisation dynamics of carbonyl sulphide (OCS)
Authors: Lomas James , Heathcote David , De Matos Loja Alexandre , Milešević Dennis , Robertson Patrick , Paterson Martin J , Vallance Claire
Published: December 2024

We present the results of a velocity-map imaging study into the dissociative electron ionisation dynamics of OCS at electron energies of 50, 75, and 100 eV, supported by new equation-of-motion coupled cluster and complete active space self consistent field (CASSCF) potential energy surface (PES) calculations for the OCS+ cation and OCS2+ dication. We report partial ionisation cross-sections and scattering distributions for the observed ionic fragments, and interpret these in terms of the dissociation dynamics of the singly and doubly charged OCS parent ions formed in the electron–molecule collisions. For many of the dissociation channels, consideration of the calculated PESs supplemented by comparison with data from photoionisation studies provides insight into the electronic PESs involved. For fragmentation products arising from dissociation of the dication, time-of-flight and recoil-frame covariance maps provide mechanistic insight into the stepwise dissociation mechanisms leading to these products and support previous conclusions by other authors.
Electron-impact ionization of Si IV–VIII in hot plasmas
Authors: Pain Jean-Christophe , Benredjem Djamel
Published: December 2024

In this work, we investigate the ionization of silicon by electron impacts in hot plasmas. Our calculations of the cross sections and rates rely on the Coulomb-Born-exchange, binary-encounter-dipole and distorted-wave methods implemented in the Flexible Atomic Code, and are compared with measurements and other theoretical values. We use a semi-empirical formula for the cross section, which involves a small set of adjustable parameters. Configuration interaction is taken into account and is shown to affect the cross section at low energy, in particular for Si3+. The rate coefficient is then expressed in terms of these parameters and is represented in a large temperature interval, up to 108 K. As expected, the agreement with measurements improves for increasing ion charges, confirming the applicability of our approach to hot plasma studies such as inertial-confinement fusion, and its reliability.
Cr3+ doped ZnGa2O4 micro-flowers as stable saturable absorber media
Authors: Choudhury Shouvik , Sirohi Sugandh , Narayanan Shruti , Bisht Prem B
Published: December 2024

Micro-flowers of Cr3+ doped ZnGa2O4, a spinel compound with high chemical and thermal stability is synthesized by hydrothermal method. Flower-like structures in the micrometer range made up of secondary nanoflakes are evident from the field emission scanning electron microscope images. X-ray photoelectron spectroscopy studies confirm the presence of Cr3+ dopants. The steady-state optical characterizations show higher absorbance of the samples in the ultraviolet (UV) region. Due to introduction of the d–d electron transition states of Cr3+ ions, ZnGa2O4:Cr3+ exhibits a prominent red near infrared (NIR) luminescence. Optical nonlinearity studies show that Cr3+ doping changes the nonlinear absorption from reverse saturable absorption to saturable absorption. This is due to the introduction of an excitation band owing to 4T1-4A2 transition of Cr3+ ion.
A generalized zero-shot semantic learning model for batch process fault diagnosis
Authors: Liu Kai , Zhao Xiaoqiang , Mou Miao , Hui Yongyong
Published: December 2024

In industrial monitoring, although zero-shot learning successfully solves the problem of diagnosing unseen faults, it is difficult to diagnose both unseen and seen faults. Motivated by this, we propose a generalized zero-shot semantic learning fault diagnosis model for batch processes called joint low-rank manifold distributional semantic embedding and multimodal variational autoencoder (mVAE). Firstly, joint low-rank representation and manifold learning makes the training samples map to the low-rank space, which obtains the global–local features of the samples while reducing the redundancy in the inputs for the training model; secondly, the bias of human-defined semantic attributes is corrected by predicting the attribute error rate; then, fault samples and corrected semantic vectors are embedded into the consistency space, in which the samples are reconstructed using the mVAE to fully integrate the cross-modal information, meanwhile, Barlow matrix is designed to measure the consistency between the fault samples and the attribute vectors, the higher the consistency, the higher the learning efficiency of attribute classifiers; finally, the generalized zero-shot fault diagnosis experiments are designed and conducted on the penicillin fermentation process and the semiconductor etching process to validate the effectiveness, the results show that the proposed model is indeed possible to diagnose target faults without their samples.
A systematic review on interpretability research of intelligent fault diagnosis models
Authors: Peng Ying , Shao Haidong , Xiao Yiming , Yan Shen , Wang Jie , Liu Bin
Published: December 2024

Recent years have witnessed a surge in the development of intelligent fault diagnosis (IFD) mostly based on deep learning methods, offering increasingly accurate and autonomous solutions. However, they overlook the interpretability of models, and most models are black-box models with unclear internal mechanisms, thereby reducing users’ confidence in the decision-making process. This is particularly problematic for critical decisions, as a lack of clarity regarding the diagnostic rationale poses substantial risks. To address these challenges, a more reliable, transparent, and interpretable system is urgently demanded. Research on the interpretability of IFD has gained momentum and stands today as a vibrant area of study. To promote in-depth research and advance the development of this field, a thorough examination of existing journal articles on interpretable fault diagnosis models is essential. Such a review will demystify current technologies for readers and provide a foundation for future investigation. This article aims to give a systematic review of the state-of-the-art interpretability research in the field of IFD. We present a systematic review of recent scholarly work on interpretable models in this domain, categorizing them according to their methodologies and structural attributes. In addition, we discuss the challenges and future research directions for the interpretability of IFD.
Impact of nuclear fragmentation on the stopping power ratio of 12C ion beams
Authors: Saße Pascal , Stolzenberg Jessica , Baumann Kilian , Poppe Björn , Looe Hui Khee
Published: December 2024

Objective: Nuclear fragmentation generates a diverse dosimetric environment in the path of 12C ion beams. Concise parametrization of the beam’s composition is paramount for determining key correction factors in clinical dosimetry. This study sets out to provide such a parametrization based on detailed Monte Carlo simulations of clinically relevant 12C beams. Special attention was paid to the products of nuclear fragmentations and their importance in determining the stopping power ratios. Approach: Using the Monte Carlo simulation package GATE, the spectral fluence of all primary and secondary particles in water were computed at different depths for selected clinically relevant incident energies. Collision-stopping power data was taken from the ICRU90, SRIM and MSTAR database, as well as from previous publications. Main results: The choice of stopping power data was shown to have a bigger impact on the resulting stopping power ratio than the choice of physics lists for the simulations. Significance: A comprehensive analysis of the relationship between fragmentation and dosimetric data has been provided. This study compared different methods for determining spectral fluence-based stopping power ratios, which is essential for accurate ion beam dosimetry.
Simulating atherosclerotic plaque mechanics using polyvinyl alcohol (PVA) cryogel artery phantoms, ultrasound imaging and inverse finite element analysis
Authors: Guendouz Yasmine , Razif Noor Adeebah Mohamed , Bernasconi Floriane , Brien Gordon O’ , Johnston Robert D , Lally Caitríona
Published: December 2024

The clinical decision to establish if a patient with carotid disease should undergo surgical intervention is primarily based on the percent stenosis. Whilst this applies for high-grade stenosed vessels (>70%), it falls short for other cases. Due to the heterogeneity of plaque tissue, probing the mechanics of the tissue would likely provide further insights into why some plaques are more prone to rupture. Mechanical characterization of such tissue is nontrivial, however, due to the difficulties in collecting fresh, intact plaque tissue and using physiologically relevant mechanical testing of such material. The use of polyvinyl alcohol (PVA) cryogel is thus highly convenient because of its acoustic properties and tunable mechanical properties. Methods. The aim of this study is to demonstrate the potential of PVA phantoms to simulate atherosclerotic features. In addition, a testing and simulation framework is developed for full PVA vessel material characterization using ring tensile testing and inflation testing combined with non-invasive ultrasound imaging and computational modeling. Results. Strain stiffening behavior was observed in PVA through ring tensile tests, particularly at high (n = 6) freeze–thaw cycles (FTCs). Inflation testing of bi-layered phantoms featuring lipid pool inclusions demonstrated high strains at shoulder regions. The application of an inverse finite element framework successfully recovered boundaries and determined the shear moduli for the PVA wall to lie within the range 27–53 kPa. Conclusion. The imaging-modeling framework presented facilitates the use and characterization of arterial mimicking phantoms to further explore plaque rupture. It also shows translational potential for non-invasive mechanical characterization of atherosclerotic plaques to improve the identification of clinically relevant metrics of plaque vulnerability.
The role of local active stiffness on the natural frequency of a flexible propulsor
Authors: Rodriguez Miguel Perilla , Musgrave Patrick F
Published: December 2024

This study identifies how local changes in active stiffness affect the natural frequency of a bio-inspired flexible propulsor. Biological swimmers actively change their body stiffness and natural frequency to maintain high swimming performance during steady swimming, acceleration, and maneuvering. However, it is not well understood how local active stiffness along the body affects the propulsor’s global stiffness and natural frequency. This study identifies the relationship between the propulsor’s natural frequency and the magnitude, spatial location, and application length of the active stiffness. We use a numerical kinematic model of a flexible bio-inspired propulsor with Euler–Bernoulli beam theory, inertial fluid-structure interactions, and active stiffness via co-contraction of piezoelectric artificial muscles to generate local in-plane forces. Using this numerical model, we uncover the fundamental mechanism by which the in-plane forces change the natural frequency. Local in-plane compressive forces increase the natural frequency, and there is a critical compressive force at which the propulsor’s first and second natural frequencies converge to yield a dynamic instability. We establish that the change in natural frequency is governed by the interplay between the spatial location and application length of the active stiffness. The propulsor is most sensitive to changes in natural frequency when the active stiffness is applied at the propulsor’s peduncle, but the largest changes in natural frequency occur when the active stiffness is applied with a long muscle centered along the anterior–posterior axis. We show that artificial muscles can change the natural frequency via local in-plane forcing, but practical implementation will require artificial muscles with high ratios of blocking force to passive muscle stiffness. These results serve as a framework for future studies that will identify the relationship between swimming performance (thrust and efficiency) and locally applied active stiffness.
Influence of Fe2O3 and La2O3 nanoparticles on the performance of domestic refrigerator functioning with R134a refrigerant
Authors: Prabu R , Velmurugan D , Vijayakumar S R , Maniyarasan M
Published: December 2024

Domestic refrigerator is working on the principle of Vapour Compression Refrigeration (VCR) system. VCR system uses compressor as one the functional member which consumes electrical energy. Due to the civilization, the usages of VCR system based equipments are increasing. Therefore, the need for electrical energy is on the rise. Therefore, the limited usage of electrical energy is desirable. Consequently, this study aimed to reduce electrical energy consumption and enhance the performance of the VCR system by using nano-refrigerants as the working medium. This research utilized two types of nano-refrigerants: R134a/Fe2O3 and R134a/La2O3.The nanoparticles concentration was varied from 0.1 g l−1 to 0.5 g l−1 and the best refrigerant was identified by comparing the performance of VCR operated with aforementioned nano-refrigerants. The properties like thermal conductivity and viscosity of nano-refrigerants were determined and compared with R134a refrigerant. Further, the power consumption, pull down time and COP of VCR system was investigated. Results revealed that the R134a/Fe2O3 and R134a/La2O3 nano-refrigerant displayed superior characteristics and showed greater performance. The R134a/Fe2O3 demonstrated a peak thermal conductivity (0.022 W mK−1) when 0.5 g l−1 of nanoparticles were added. Further, the same refrigerant showed 27.4% decrease in electrical energy consumption compared to R134a refrigerant and showed a maximum COP of 3.5. Therefore, this study suggests that the R134a/0.5 g l−1 Fe2O3 could be an effective choice to lower the power consumption of the VCR system.
Performance analysis based on biomolecule position and pH-sensing mechanism for vertical TFET
Authors: Wadhwa Girish , Thakur Anchal , Taibi Angelo , Proto Antonino
Published: December 2024

In this study, the impact of the diffusion mechanism of a biomolecule in the nanocavity (

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o

) region on the electrical characteristics of a split-gate, step-channel electrolyte-insulated semiconductor vertical TFET (SGSC-EIS-VTFET) pH biosensor was investigated. The impact of the transport sensing mechanism, that is, diffusion-limited process and rapid mixing process of biomolecules in the nanocavity sensing area, on the pH of the analyte was also examined. Physics-based modelling was used to determine the interface charge density at the oxide-silicon interface of the proposed vertical TFET pH biosensor. We also considered the effect of pH values on the proposed device performance, like drain current (I
ds), transconductance (gm), current sensitivity (SID), and voltage sensitivity (SV) after the inclusion of electrolyte medium. Here, the maximum SV ∼ 145 mH pH−1 for

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= 6 nm, which is higher than the Nernstian limit (59.2 mV pH−1), and SID has been enhanced by 10 times per pH variation. This study indicated that the diffusion of biomolecules significantly impacts the performance parameters of the proposed structure because of the realistic dominance of the sensing mechanism and the conjugation of analyte on the sensing area.
Oxidation temperature influence on the properties of oxide layers thermally grown on 4H-SiC by wet oxidation
Authors: Dartora G H S , Radtke C , Stedile F C
Published: December 2024

The compositional characteristics of oxide layers thermally grown on 4H-SiC were investigated as a function of oxidation temperature. We tracked the evolution of the oxide properties over different oxidation times. Two distinct oxidation regimes were identified: an initial phase where a substoichiometric oxide forms, followed by its conversion into SiO2. Oxidation temperature proved to be a key parameter in achieving stoichiometric SiO2. At the lowest temperature used in this study (900 °C), only substoichiometric layers were produced. Additionally, our results indicate a similar behavior for both wet and dry SiC oxidation processes, suggesting that both involve a multi-step mechanism.
A local infall from a cosmographic analysis of Pantheon+
Authors: Sorrenti Francesco , Durrer Ruth , Kunz Martin
Published: December 2024

We present a model independent analysis of the Pantheon+ supernova sample and study the dependence of the recovered values of H
0, q
0 and j
0 on the redshift cut and on the modeling of peculiar velocities. In addition to the bulk velocity discussed previously, we also find a significant infall that we attribute to the presence of an overdensity out to a radius of R ≃ 120h
-1Mpc.