bluuebunny/crossref_metadata_2025 huggingface dataset:
Power output fluctuations and unsteady aerodynamic loads of a scaled wind turbine subjected to periodically oscillating wind environments
Authors: Aju Emmanuvel Joseph , Gong Pengyao , Kumar Devesh , Rotea Mario A. , Jin Yaqing
Published: September 2024

Wind tunnel experiments were performed to quantify the coupling mechanisms between incoming wind flows, power output fluctuations, and unsteady tower aerodynamic loads of a model wind turbine under periodically oscillating wind environments across various yaw misalignment angles. A high-resolution load cell and a data logger at high temporal resolution were applied to quantify the aerodynamic loads and power output, and time-resolved particle image velocimetry system was used to characterize incoming and wake flow statistics. Results showed that due to the inertia of the turbine rotor, the time series of power output exhibits a distinctive phase lag compared to the incoming periodically oscillating wind flow, whereas the phase lag between unsteady aerodynamic loads and incoming winds was negligible. Reduced-order models based on the coupling between turbine properties and incoming periodic flow characteristics were derived to predict the fluctuation intensity of turbine power output and the associated phase lag, which exhibited reasonable agreement with experiments. Flow statistics demonstrated that under periodically oscillating wind environments, the growth of yaw misalignment could effectively mitigate the overall flow fluctuation in the wake region and significantly enhance the stream-wise wake velocity cross correlation intensities downstream of the turbine hub location.
Intracluster reaction dynamics of NO+(H2O)n
Authors: Tachikawa Hiroto
Published: September 2024

Nitric oxide (NO) and NO–water clusters play crucial roles in the D-region of the atmosphere because it is postulated that NO+ reacts with H2O to produce nitrous acid (HONO) and H3O+. HONO is the major precursor of the hydroxyl radicals leading to the formation of secondary pollutants. The sources of atmospheric HONO, however, are not fully understood. Previously, the sequential H2O addition reaction, H2O + NO+(H2O)n, and the bi-molecular collision reaction, NO+ + (H2O)n, have been investigated by both experiments and theoretical calculations to determine the formation mechanism of HONO. However, the photo-reactions from NO(H2O)n neutral clusters were not considered for the formation mechanism of HONO. In this study, the intra-cluster reactions of NO+(H2O)n clusters, following ionization of the parent neutral cluster of NO(H2O)n, were investigated using the direct ab initio molecular dynamics method. When n = 4, [NO+(H2O)4]ver [vertical ionization state of NO(H2O)n] yielded HONO and hydrated H3O+ after the intra-cluster reaction, and the reaction time was calculated to be 150 fs. The reaction is expressed as [NO+(H2O)n]ver → HONO + H3O+(H2O)n−2 (reactive) (n > 3). Larger clusters of [NO+(H2O)n]ver (n = 5–8) also yield HONO. In contrast, in smaller clusters (n = 1–3), only solvent re-orientation around NO+ occurred after the ionization: [NO+(H2O)n]ver → NO+(H2O)n (solvent re-orientation) (n = 1–3). The hydration energy of H3O+, which depends on the cluster size (n), plays an important role in promoting the formation of HONO. The reaction mechanism is discussed based on theoretical results.
A cross-fluid heat transfer analysis using neural networks over porous rotating disk
Authors: Ullah Fahim , Ashraf Muhammad Bilal
Published: September 2024

This research explores the complex interaction of incompressible cross-fluid flow, heat, and mass transfer characteristics on a porous rotating disk. The study employs sophisticated mathematical methods, including similarity transformations, to convert governing partial differential equations into nonlinear ordinary differential equations. These equations are then solved using a sophisticated numerical method, the fourth-class boundary value problem. We employ an Artificial Neural Networks algorithm with backpropagation Levenberg–Marquardt Scheme to analyze the heat transfer mechanism quantitatively. Our results provide accurate values for the Nusselt number, the Sherwood number, and the skin friction coefficient. The examination addresses this complex system's fluid mechanics and transport phenomena with potential applications in engineering and industrial processes.
Direct numerical simulation for backward-facing step flow with turbulence anisotropy analysis in a fully staggered curvilinear grid
Authors: Park Sungtek
Published: September 2024

A coordinate transformation for a finite difference method using a fully staggered curvilinear grid is applied to solve the incompressible Navier–Stokes equation with a direct numerical method. Without turbulence models, backward facing step simulations are performed with Reynolds numbers ranging from 1.5 × 104 to 3.7 × 104. From a time-averaged result, it is shown that the mainstream velocity rapidly decreases, and downward momentum increases near the end of the recirculating vortex region because of a drastic change of the effective cross-sectional area from the time-averaged flow. The turbulent fluctuation and Reynolds stress are intensified near the end of the recirculating vortex, in which the results show reasonable agreements with the experiment. The Reynolds-averaged Navier–Stokes (RANS) turbulence model and large eddy simulation (LES) are also performed using OpenFOAM. Although the RANS model could not produce the turbulent fluctuations, the time-averaged velocity profile shows a reasonable agreement with the experiment. For the LES, the viscosity near the boundary layer is overestimated due to the sub-grid scale eddy viscosity, thus it could not resolve the boundary layer correctly which leads different trend of velocity profile compared to the experiment. Turbulent anisotropic behaviors are also studied with the turbulent anisotropic invariant map. From the result, it is confirmed that turbulent anisotropic behaviors show different characteristics depending on the location of the backward-facing step, and the anisotropic behavior which is close to the isotropic is only observed in the two-separated narrow regions after the step where the gradient of the root mean square magnitude of velocity fluctuation is starting to increase.
Polaron inhibited
α
-trizinc bis-phosphate(v) as low potential polyanionic negative electrode for lithium-ion batteries
Authors: Sasirajan Littleflower Sajan Raj , Dhanapal Vaishnavi , Ramakrishnan Saraswathi , Hanamantrao Desai Prashant , Kumar Karthick , Lee Chang Woo , Vediappan Kumaran
Published: September 2024

This work explores polyanionic phosphate-type α-Zn3(PO4)2 (ZP) as a negative electrode in lithium-ion batteries. It has a high theoretical capacity of 278 mA h g−1. The crystal structure of ZP is elucidated, and Patterson's electron density profiling is performed to understand the possible site of lithiation. To address the polaron-driven electrical insulation common to phosphates, we use superficial carbon coating (ZP/C). Furthermore, the electrochemical analysis of ZP and ZP/C is performed to validate the half-cell performance and Li+ kinetics. ZP/C delivers a high capacity of 260 mA h g−1 at 0.1 C. The positive effect of carbon coating is evident from a 100-fold increase in lithium diffusion coefficient from the galvanostatic intermittent titration technique. In addition, temperature-driven capacity performance is analyzed at −10, 25, and 50 °C. Temperature gradient charge–discharge is performed between −10 and −5 °C, where the discharge capacity increases from 70 to 100 mA h g−1 at 1 C rate, extending the application toward low-temperature non-carbonaceous energy storage solutions.
Epitaxial growth of rutile GeO2 via MOCVD
Authors: Rahaman Imteaz , Duersch Bobby G. , Ellis Hunter D. , Scarpulla Michael A. , Fu Kai
Published: September 2024

Rutile germanium dioxide (r-GeO2) has been identified as an ultrawide bandgap semiconductor recently, featuring a bandgap of 4.68 eV—comparable to Ga2O3—but offering bipolar dopability, higher electron mobility, higher thermal conductivity, and higher Baliga figure of merit (BFOM). These superior properties position GeO2 as a promising material for various semiconductor applications. However, the epitaxial growth of r-GeO2, particularly in its most advantageous rutile polymorph, is still at an early stage. This work explores the growth of r-GeO2 using metal-organic chemical vapor deposition (MOCVD) on an r-TiO2 (001) substrate, utilizing tetraethyl germane as the precursor. Our investigations reveal that higher growth temperatures significantly enhance crystalline quality, achieving a full width at half maximum of 0.181° at 925 °C, compared to 0.54° at 840 °C and amorphous structures at 725 °C. Additionally, we found that longer growth durations increase surface roughness due to the formation of faceted crystals. Meanwhile, adjusting the susceptor rotation speed from 300 to 170 RPM plays a crucial role in optimizing crystalline quality, effectively reducing surface roughness by approximately 15 times. This study offers a foundational guide for optimizing MOCVD growth conditions of r-GeO2 films, emphasizing the crucial need for precise control over deposition temperature and rotation speed to enhance adatom mobility and effectively minimize the boundary layer thickness.
Modifications to Swisdak (2013)'s rejection sampling algorithm for a Maxwell–Jüttner distribution in particle simulations
Authors: Zenitani Seiji
Published: September 2024

Modifications to Swisdak's [Phys. Plasmas 20, 062110 (2013)] rejection sampling algorithm for drawing a Maxwell–Jüttner distribution in particle simulations are presented. Handy approximations for e-folding points and a linear slope in the envelope function are proposed, to make the algorithm self-contained and more efficient.
Transport dynamics of droplets encapsulated by an elastic interface in pore throats
Authors: He Long , He Wenjing , Wang Saipin , Lou Rui , Ren Tong , Cui Hao , Tao Yiwen , Yuan Yuejin
Published: September 2024

The transport dynamics of droplets in pore throats are crucial for oil recovery in high water-cut oil fields and primarily governed by interfacial properties of droplets. In nanoparticle flooding, nanoparticle surfactants adsorb onto the oil droplet interface, forming a “solid-like” interface that predominantly exhibits elastic properties. Owing to the demonstrated effect of the elastic interface on droplet deformation, new behaviors of droplets encapsulated by an elastic interface would exist when transported through pore throats. In this paper, an elastic interface model was developed and fluid–structure coupling was used to simulate the transport dynamics of elastic interface droplets under the variation of capillary numbers, viscosity ratios, and pore throat structures. The findings showed that: (1) In symmetric pore throats, elastic interface droplets require a higher critical capillary number to pass through compared to clean droplets. The elastic interface restricts the deformation and velocity of droplets when passing through the pore throats. (2) In asymmetric pore throats, the deformation and pass through of elastic interface droplets are inhibited with increasing asymmetry. The restriction effect of elastic interface on droplets transport in the pore throats is consistent at various asymmetries. These results enhance the understanding of droplet transport dynamics in pore throats and provide new insights for improving nanoparticle-enhanced oil recovery technology.
Dislocation evolution and hardening of CoCrFeMnNi high entropy alloy under Fe ion irradiation at room temperature and 500 °C
Authors: Zhang Lisong , Zhang Peng , Li Na , Zhang Xiaonan , Mei Xianxiu
Published: September 2024

Recently, high entropy alloy (HEA) has become a research hotspot as a new candidate structural material in nuclear reactors due to its good irradiation resistance in swelling and hardening. Focusing on the temperature effect of irradiation damage, this work investigated the influence of irradiation temperature on dislocation evolution and irradiation hardening of HEAs. CoCrFeMnNi HEA was irradiated by high-energy Fe ions at room temperature and 500 °C. It was found that dense small dislocations were produced in the damage attenuation region (i.e., the tail of the ion range) of HEAs after irradiation at room temperature, whereas the irradiation-induced dislocations could not be observed in the damage attenuation region when the irradiation temperature was increased to 500 °C. For the small-sized dislocations, dissociation may occur more easily than long-range migration in HEAs (such as CoCrFeNi systems) due to the inhibition of defect migration and the decrease in defect binding energy, and this order is reversed in pure metals (such as Ni, W). Therefore, at 500 °C irradiation, small dislocations in the damage attenuation region of CoCrFeMnNi HEAs were dissociated before migrating to deeper regions, thereby resulting in the depth of dislocation distribution smaller than the stopping and range of ions in matter-calculated damage stopping depth, unlike the phenomenon in pure metals where dislocations migrated to regions exceeding the calculated depth. In addition, the dislocation density of CoCrFeMnNi HEAs decreased significantly due to the promotion of dissociation and merging of dislocations by elevated temperatures, and the hardening after 500 °C irradiation was less than that after room temperature irradiation.
The vibration of deep-sea mining riser excited by both internal and external flows
Authors: Zhu Hongjun , Zhou Mai , Gao Yue , Zhang Wenxiang , Zhou Tongming
Published: September 2024

This paper reports the experimental results of the coupling response of a catenary flexible riser excited by both internal liquid–solid two-phase flow and the external shear current. The conveyed flow density ranges from 1000 to 1200 kg/m3, with velocity changing from 0 to 2.15 m/s. The vibration of the flexible riser was tested in the depth-averaged reduced velocity (Ur) range of 4.52–54.05. The experimental results indicate that only the in-plane response is excited by the internal liquid–solid flow when the riser is immersed in still water. As either the internal flow density (ρin) or velocity (uin) grows, the in-plane response is enhanced, resulting in the augmented fluctuations of pressure difference and top tension. In the presence of external flow, the out-of-plane response is also excited. The critical reduced velocity for mode transition becomes larger as either uin or ρin increases. Nonetheless, both the in-plane and out-of-plane responses are not sensitive to the internal flow when Ur is sufficiently high. Generally, the out-of-plane response is predominately contributed from the external flow, while the internal liquid–solid flow is the main contributor to the in-plane response at lower Ur.
Assessing changes in high-intensity fire events in south-eastern Australia using Fourier Transform Infra-red (FITR) spectroscopy
Authors: Ryan Rebecca , Thomas Zoë , Simkovic Ivan , Dlapa Pavel , Worthy Martin , Wasson Robert , Bradstock Ross , Mooney Scott , Haynes Katharine , Dosseto Anthony
Published: September 2024

Background As fire regimes continue to evolve in response to climate change, understanding how fire characteristics have responded to changes in the recent past is vital to inform predictions of future fire events. Aims and methods Using Fourier Transform Infrared (FTIR) spectroscopy, we assessed how fire intensity has changed in two fire-prone landscapes in south-eastern Australia: (1) the Blue Mountains; and (2) Namadgi National Park during the past 3000 years. Key results Higher aromatic/aliphatic ratios suggest increased high-intensity fire frequency in sediments at the surface of both cores. Increases in the frequency of extreme drought periods, coupled with the change in vegetation and anthropogenic ignitions following colonisation, could have increased the frequency of high-intensity fires in the past ~200 years. Conclusions FTIR spectroscopy can be used in sediment deposits to infer that the frequency of high-intensity fire events has increased in the past 200 years compared to the previous ~3000 years. Implications These results are important for understanding how past fire regimes have responded to climate, people and vegetation shifts in the past ~3000 years and can be used to inform models for future predictions and management strategies.
Finite Size Effect on Gluon Dissociation of J/ψ in Relativistic Heavy Ion Collisions
Authors: Wang 王 Jingjing 静静 , Chen 陈 Baoyi 保义 , Liu 刘 Yunpeng 云朋
Published: September 2024

Thermal quantities, including the the entropy density and gluon spectrum, of quark matter within a box that is finite in the longitudinal direction are calculated using a bag model. Under the assumption of entropy conservation, the corresponding gluon dissociation rate of J/ψ is studied. It reaches a maximum at a certain longitudinal size L
m, below which the suppression is weak even if the temperature becomes higher than that without the finite size effect, and above which the dissociation rate approaches to the thermodynamic limit gradually with increasing longitudinal size of the fireball.
Self-Assembly of Bacteria in Alternating-Current Electric Fields
Authors: Li 李 Yan-Ran 艳冉 , Zong 宗 Yi-Wu 奕吾 , Zhang 张 Hong 红 , Zhang 张 Jing-Chao 静超 , Feng 冯 Chun-Ying 春迎 , Qiao 乔 Jian-Jun 建军 , Song 宋 Hao 浩 , Zhao 赵 Kun 坤
Published: September 2024

Self-assembly of bacteria in electric fields is a promising route to fabricate biomaterials with reversible and specific structures. However, due to relatively less studies, our understanding of the self-assembly of bacteria in electric fields is still incomplete. Particularly, how different bacterial species behave differently in their field-mediated self-assembly behavior remains to be disclosed. In this study, we choose four bacterial species, including Shewanella oneidensis, Pseudomonas aeruginosa, Bacillus subtilis and Lactococcus lactis as model systems, and investigate their self-assembly behavior in alternating-current (AC) electric fields for both diluted and concentrated suspensions. The phase diagrams in the plane of applied field strength vs frequency are obtained. The results show that in diluted suspensions, a transition sequence of isotropic–paranematic–string–columnar phases is observed in all strains as the field strength increases. Details of the assembled structures are quantitatively differentiated among different strains. In concentrated suspensions, besides the isotropic and paranematic phases, a higher ordered phase with interdigitating rectangular crystal domains (OIR) and an ordered phase with smectic A liquid crystal domains are observed for S. oneidensis and P. aeruginosa, respectively. Our findings shed new light on fabricating potential biomaterials by assembling cells of appropriately chosen bacterial species that have desired surface properties under AC electric fields.
Fermi Surface Nesting with Heavy Quasiparticles in the Locally Noncentrosymmetric Superconductor CeRh2As2
Authors: Wu Yi , Zhang Yongjun , Ju Sailong , Hu Yong , Huang Yanen , Zhang Yanan , Zhang Huali , Zheng Hao , Yang Guowei , Eljaouhari Evrard-Ouicem , Song Baopeng , C. Plumb Nicholas , Steglich Frank , Shi Ming , Zwicknagl Gertrud , Cao Chao , Yuan Huiqiu , Liu Yang
Published: September 2024

The locally noncentrosymmetric heavy fermion superconductor CeRh2As2 has attracted considerable interests due to its rich superconducting phases, accompanied by possible quadrupole density wave and pronounced antiferromagnetic excitations. To understand the underlying physics, here we report measurements from high-resolution angle-resolved photoemission. Our results reveal fine splittings of the conduction bands related to the locally noncentrosymmetric structure, as well as a quasi-two-dimensional Fermi surface (FS) with strong 4f contributions. The FS shows signs of nesting with an in-plane vector
q

1 = (π/a, π/a), which is facilitated by the heavy bands near

X
¯

arising from the characteristic conduction-f hybridization. The FS nesting provides a natural explanation for the observed antiferromagnetic spin fluctuations at (π/a, π/a), which might be the driving force for its unconventional superconductivity. Our experimental results can be reasonably explained by density functional theory plus dynamical mean field theory calculations, which can capture the strong correlation effects. Our study not only provides spectroscopic signature of the key factors underlying the field-induced superconducting transition, but also uncovers the critical role of FS nesting and lattice Kondo effect in the underlying magnetic fluctuations.
Growth of Ba2CoWO6 single crystals and their magnetic, thermodynamic and electronic properties
Authors: Hanna A R N , Islam A T M N , Ritter C , Luther S , Feyerherm R , Lake B
Published: September 2024

This study explores the bulk crystal growth, structural characterization, and physical property measurements of the cubic double perovskite Ba2CoWO6 (BCWO). In BCWO, Co2+ ions form a face-centred cubic lattice with non-distorted cobalt octahedra. The compound exhibits long-range antiferromagnetic order below T
N = 14 K. Magnetization data indicated a slight anisotropy along with a spin-flop transition at 10 kOe, a saturation field of 310 kOe and an ordered moment of 2.17 µB at T = 1.6 K. Heat capacity measurements indicate an effective j = 1/2 ground state configuration, resulting from the combined effects of the crystal electric field and spin-orbit interaction. Surface photovoltage analysis reveals two optical gaps in the UV–Visible region, suggesting potential applications in photocatalysis and photovoltaics. The magnetic and optical properties highlight the significant role of orbital contributions within BCWO, indicating various other potential applications.
Planar XY magnetic glass state in the Gd2ScNbO7 pyrochlore
Authors: Mauws C , Beare J , Rutherford M R , Su Y , Sharma S , Nugent M , Lee M K , Chang L J , Dunsiger S R , Gardner J S , Luke G M , Wiebe C R
Published: September 2024

Here a spin glass system with emergent planar ordered spin clusters is investigated. The mixed B-site pyrochlore Gd2ScNbO7 has been synthesized and characterized through a variety of techniques, including x-ray diffraction, magnetic susceptibility, muon spin relaxation, heat capacity and neutron scattering. Despite a Curie–Weiss temperature of −3.93(3) K, indicating net antiferromagnetic interactions, no signs of long ranged magnetic ordering are found down to T = 0.3 K. Instead, a disordered magnetic state emerges with a small correlation length of 2.1(1) Å of single tetrahedra. A Reverse Monte Carlo analysis of the polarized neutron scattering data reveals short-range antiferromagnetic order with emergent XY spin ordering similar to the parent pyrochlore compounds. Muon spin relaxation, and AC susceptibility measurements confirm that the magnetization condenses into a glass, with 10 % of the potential entropy missing in the specific heat. This magnetic ground state is similar to what is observed in Gd2Sn2O7 just above the ordering temperature, without the eventual long-range ordering at low temperature.
Entanglement harvesting in buckled honeycomb lattices by vacuum fluctuations in a microcavity
Authors: Arreyes Facundo , Escudero Federico , Sebastián Ardenghi Juan , Juan Alfredo
Published: September 2024

We study the entanglement harvesting between two identical buckled honeycomb lattices placed inside a planar microcavity. By applying time dependent perturbation theory, we obtain quantum correlations between both layers induced by the cavity field. Considering the vacuum state as the initial state of the cavity field and tracing out the time-evolved degrees of freedom, we analyze the entanglement formation using the concurrence measure. We show that the concurrence depends on the virtual photon exchanged and the positions of the layer through the interlayer photon propagator. Furthermore, we find that the formation of entanglement between equal energy electrons tends to be enhanced when they move in perpendicular directions. Our results indicate that a buckled honeycomb structure and a large spin-orbit interaction favor the entanglement harvesting.
Roadmap on industrial imaging techniques
Authors: Lee Jung-Ryul , Yoo Hongki , Ciang Chia Chen , Kim Young-Jin , Kim Daehee , Teo Teow Wee , Mahdavipour Zeinab , Abdullah Azizi , Khoo Bee Ee , Abdullah Mohd Zaid , Iakovidis Dimitris K , Vartholomeos Panagiotis , Yacoot Andrew , Cai Tao , Kim Mirae , Kim Kyung Chun , Ye Jiamin , Liang Xiao , Cao Lidan , Wang Xingwei , Huang Jianqing , Cai Weiwei , Wu Yingchun , da Silva Marco J , Tan Chao , Bhattacharya Sayantan , Vlachos Pavlos , Cierpka Christian , Rossi Massimiliano
Published: September 2024

Imaging plays a vital role in enabling the visualization and analysis of objects and phenomena across various scientific disciplines and industrial sectors, spanning a wide range of length and time scales. This roadmap presents a critical overview of 13 industrial imaging techniques, which are organized into three thematic categories according to their applicability to either solid, fluid, or both solid and fluid targets. The objectives of this roadmap are to highlight challenges and provide perspectives for next-generation imaging systems, which can serve as a guide to researchers and funding agencies in identifying new prospects. It has been found that the common challenges of imaging techniques have remained fundamentally unchanged over the years, including improving coverage, speed, resolution, accuracy, and robustness; however, there is an increasing reliance on data-driven or artificial intelligence (AI) approaches. Addressing these challenges necessitates easy access to high-performance computing resources. Notably, the trustworthiness and traceability of AI approaches should be enhanced through the sharing of benchmarking data, balancing with physics-based techniques, and the adoption of more explainable AI.
Distributed wireless IoT based sensing and quality monitoring system in protection of wetlands groundwater areas
Authors: Radić Jelena , Brkić Miodrag , Keser Tomislav , Obrovski Boris , Mihajlović Ivana , Toskić Marko Vasiljević
Published: September 2024

This paper presents the development and implementation of a sensor network based on the Internet of Things (IoT) for monitoring key groundwater quality parameters to minimize potential risks in biodiversity conservation. These water monitoring parameters include the water level, water temperature, pH, conductivity, and dissolved oxygen (DO). The system ensures scalability, ease of use, real-time data acquisition and minimal power consumption resulting in efficient and reliable water quality monitoring with the convenience of remote sensing. The continuous measurement system was set up to be a single source of information for monitoring groundwater quality in protected wetland areas across international borders, including Tompojevacki Ritovi (Municipality of Tompojevci, Croatia) and Lake Zobnatica (Municipality of Backa Topola, Serbia). The data collected over one year and three months by the wireless sensor network (WSN) monitoring were compared to standard laboratory method results to demonstrate the accuracy and precision of the WSN measurements. The relative mean (average) error for the WSN measurements compared with the laboratory analyses results have the following values: 8.8% for pH, 10.3% for DO, 33.7% for conductivity on sites in Tompojevci; 4.6% for pH, 12.8% for DO, 29.5% for conductivity on sites in Lake Zobnatica. Appropriate calibration and installation of the WSN give a larger volume of data and thus grow the database, allowing for a more accurate identification of water contamination and a quick response in the event of pollution. Smart IoT-based sensors help to protect water quality and, as a result, the well-being of ecosystems and human communities, which is especially important in protected areas like wetlands.
A 6 month-long real-time time scale steered to NIM-Sr1 optical lattice clock
Authors: Zhu Lin , Wang Qiang , Wang Yuzhuo , Lin Yige , Yang Dongfang , Li Ye , Yang Tao , Meng Fei , Lin Baike , Tian Haochen , Lu Bingkun , Fang Zhanjun
Published: September 2024

NIM-Sr1 optical lattice clock has been operated intermittently for seven consecutive months with an operation uptime around 13.8%, which serves as the reference to steer a hydrogen maser for generating a real-time time scale TS(Sr1). The peak-to-peak time difference of TS(Sr1) compared to UTC is 1.8 ns within 180 d and is less than 0.5 ns within the last month, after correcting the time error induced by a time transfer link abnormality. A dedicated automation system with hardware and software is developed to monitor the operation status of NIM-Sr1, process the measurement data, and periodically predict the hydrogen maser frequency. According to the simulation results, a composite algorithm based on both Kalman filtering (KF) and weighted least squares fitting (WLSF) is utilized for generating TS(Sr1). The KF is utilized when the unavailability of NIM-Sr1 is shorter than 1 d, and the WLSF with fitting interval

T

fit

=
30

 d

is utilized in other conditions leveraging the long-term predictability of the hydrogen maser. In addition, it is demonstrated by simulation and the post-processing of earlier experimental data that, a time scale with smaller time error can be achieved by shortening the WLSF interval from 30 d to about 5 d under the condition of sufficient measurement data points for reducing the statistical error.
Metal-semiconductor-metal UVA photodetector based on TiO2 thin films synthesized via liquid phase deposition method
Authors: Baqandwan Hanadi , Rajamanickam Suvindraj , Samsuri Siti Azrah Mohamad , Halim Mohd Mahadi , Pakhuruddin Mohd Zamir
Published: September 2024

In this work, titanium dioxide (TiO2) thin film-based metal-semiconductor–metal (MSM) ultraviolet (UV) photodetectors (PDs) were fabricated on glass substrates via liquid phase deposition (LPD) technique at various deposition time in the range of 3–6 h. Varying deposition time significantly impacted the physical properties of the films. Increasing the deposition time revealed a mixture of clusters and hexagonal-like structures in film’s morphology. The energy band gap of the TiO2 films decreased from 3.30 to 3.09 eV upon increasing the deposition time. Photodetection characteristics were examined by exposing the MSM UV PD to 390 nm UV light with an intensity of 1.6 mW cm−2 and a bias voltage of 5 V. The fabricated PDs implied characteristics of I-V ohmic contact. The optimum photodetection characteristics were achieved for TiO2 film deposited at 6 h which exhibited 36.9 μA maximum photocurrent, 20080.3% sensitivity, 201.80 gain, 225 mA W−1 responsivity, 81.07% external quantum efficiency, 0.276 s response time, and 0.274 s recovery time. The photoelectric properties of the films were strongly affected by the increased grain size and improved crystallinity of the films due to the prolonged deposition time. The optimum film demonstrated its potential to be a promising candidate for UV PD applications.
Relationship between self-propelled velocity and Brownian motion for spherical and ellipsoid particles
Authors: Wang 汪 Jingwen 静文 , Xu 徐 Ming 明 , Nie 聂 Deming 德明
Published: September 2024

The Brownian motion of spherical and ellipsoidal self-propelled particles was simulated without considering the effect of inertia and using the Langevin equation and the diffusion coefficient of ellipsoidal particles derived by Perrin. The Péclet number (Pe) was introduced to measure the relative strengths of self-propelled and Brownian motions. We found that the motion state of spherical and ellipsoid self-propelled particles changed significantly under the influence of Brownian motion. For spherical particles, there were three primary states of motion: 1) when Pe < 30, the particles were still significantly affected by Brownian motion; 2) when Pe > 30, the self-propelled velocities of the particles were increasing; and 3) when Pe > 100, the particles were completely controlled by the self-propelled velocities and the Brownian motion was suppressed. In the simulation of the ellipsoidal self-propelled particles, we found that the larger the aspect ratio of the particles, the more susceptible they were to the influence of Brownian motion. In addition, the value interval of Pe depended on the aspect ratio. Finally, we found that the directional motion ability of the ellipsoidal self-propelled particles was much weaker than that of the spherical self-propelled particles.
Multiframe-integrated, in-sensor computing using persistent photoconductivity
Authors: Jiang Xiaoyong , Ye Minrui , Li Yunhai , Fu Xiao , Li Tangxin , Zhao Qixiao , Wang Jinjin , Zhang Tao , Miao Jinshui , Cheng Zengguang
Published: September 2024

The utilization of processing capabilities within the detector holds significant promise in addressing energy consumption and latency challenges. Especially in the context of dynamic motion recognition tasks, where substantial data transfers are necessitated by the generation of extensive information and the need for frame-by-frame analysis. Herein, we present a novel approach for dynamic motion recognition, leveraging a spatial-temporal in-sensor computing system rooted in multiframe integration by employing photodetector. Our approach introduced a retinomorphic MoS2 photodetector device for motion detection and analysis. The device enables the generation of informative final states, nonlinearly embedding both past and present frames. Subsequent multiply-accumulate (MAC) calculations are efficiently performed as the classifier. When evaluating our devices for target detection and direction classification, we achieved an impressive recognition accuracy of 93.5%. By eliminating the need for frame-by-frame analysis, our system not only achieves high precision but also facilitates energy-efficient in-sensor computing.
The effects of neuron morphology and spatial distribution on the selectivity of dorsal root ganglion stimulation
Authors: Farooqui Juhi , Nanivadekar Ameya C , Capogrosso Marco , Lempka Scott F , Fisher Lee E
Published: September 2024

Objective. For prosthesis users, sensory feedback that appears to come from the missing limb can improve function, confidence, and phantom limb pain. Numerous pre-clinical studies have considered stimulation via penetrating microelectrodes at the dorsal root ganglion (DRG) as a potential approach for somatosensory neuroprostheses. However, to develop clinically translatable neuroprosthetic devices, a less invasive approach, such as stimulation via epineural macroelectrodes, would be preferable. This work explores the feasibility of using such electrodes to deliver focal sensory feedback by examining the mechanisms of selective activation in response to stimulation via epineural electrodes compared with penetrating electrodes. Approach. We developed computational models of the DRG, representing the biophysical properties of the DRG and surrounding tissue to evaluate neural responses to stimulation via penetrating microelectrodes and epineural macroelectrodes. To assess the role of properties such as neuron morphology and spatial arrangement we designed three models, including one that contained only axons (axon only), one with pseudounipolar neurons arranged randomly (random), and one with pseudounipolar neurons placed according to a realistic spatial distribution (realistic). Main results. Our models demonstrate that activation in response to stimulation via epineural electrodes in a realistic model is commonly initiated in the axon initial segment adjacent to the cell body, whereas penetrating electrodes commonly elicit responses in t-junctions and axons. Moreover, we see a wider dynamic range for epineural electrodes compared with penetrating electrodes. This difference appears to be driven by the spatial organization and neuron morphology of the realistic DRG. Significance. We demonstrate that the anatomical features of the DRG make it a potentially effective target for epineural stimulation to deliver focal sensations from the limbs. Specifically, we show that epineural stimulation at the DRG can be highly selective thanks to the neuroanatomical arrangement of the DRG, making this a promising approach for future neuroprosthetic development.
Roles of ECH system in DTT plasma operations
Authors: Granucci G. , Auriemma F. , Aucone L. , Baiocchi B. , Bonanomi N. , Braghin F. , Bruschi A. , Busi D. , Casiraghi I. , di Grazia L.E. , Fanale F. , Figini L. , Garavaglia S. , Mantica P. , Mattei M. , Moro A. , Nowak S. , Platania P. , Ricci D. , Rispoli N. , Romano A. , Rubino G. , Schmuck S. , Simonetto A.
Published: September 2024

The Divertor Tokamak Test (DTT) facility is equipped with auxiliary heating systems in order to be able to load the divertor with a power flux relevant to study the power exhaust issue in a reactor relevant range of parameter. The powerful system is the Electron Cyclotron Heating (ECH) with an installed power of 32 MW in its largest extension. Together with the bulk heating of the DTT plasma, the ECH system will cover several tasks for the plasma operation. This paper summarizes the main characteristics and design choices of the DTT ECH system and the related physics studies, based on the reference DTT plasma, to develop and control the plasma, fulfilling the functional tasks, with the support of simulation activities. Dedicated studies have been carried out to investigate the capability of EC power to assist plasma start-up, stabilize MHD activity and support current ramp up/down. In addition, it has been studied how changes of the ECH power distribution can have an impact on the plasma profiles, affecting the fueling pellet effectiveness and MHD modes.
A comparative analysis of flow characteristics inside a closed-ended micro-shock tube using both pressure-based and density-based algorithms
Authors: Srivastava Ayushman , Kundu Abhishek , Ranjan Paul Akshoy
Published: September 2024

This work intends to compare the pressure-based coupled algorithm and the density-based algorithm for the two-dimensional high speed gas-particle two-phase compressible flow in the closed-ends micro-shock tube. The micro-shock tube is employed in the medical sector for the drug delivery without needle. The mass along with momentum transfer equations for compressible flow, together with the computational approach, are provided. These solvers are used to perform the transient simulation. The pressure-based algorithm offers the versatility to address flow issues using either a coupled or a segregated method. Choosing the coupled technique over the non-coupled or segregated approach has some benefits. In particular, the linked scheme outperforms segregated solution techniques and provides a reliable and effective solution for steady-state flows. The den sity-based and pressure-based segregated methods using SIMPLE-type pressure-velocity coupling is replaced by this pressure-based coupled technique. Using the coupled approach becomes essential when dealing with poor mesh quality or when using high time steps in the case of transient flows. The schlieren and vorticity contours were obtained to analyze and compared for both the solvers to determine their efficacy to capture the shock waves and fluid element rotation. This is the major gap and novelty found through the literature survey for such kind of problem. The pressure histories and Mach no. were recorded for both the solvers. The result obtained through these solvers show that though the pressure-based algorithm is capable for handling high speed compressible flow problem but when it comes about the CPU time as well as the accuracy of the result, the density-based solver is more reliable for this problem.
Drag lift characteristics of a NACA 4412 airfoil with angle of attack
Authors: Ghose Prakash , Kumar Sahoo Tarak , Kumar Patel Jitendra , Kumar Nayak Swarup , Kumar Rana Basanta
Published: September 2024

Unsymmetrical airfoils are used to get a better lift-to-drag ratio. In this work, the overall performance of a NACA4412 unsymmetrical airfoil has been investigated through CFD simulations. The angle of attack is varied from 0° to 20° at the interval of 2°. The airflow velocity is kept constant at 30 m/s. From the investigation, it is observed that the optimum CL to CD ratio is obtained at an angle of attack of 5°. Beyond 5° AA, the CD rises rapidly. With an increase in AA, a backflow is observed near the trailing edge on the top half of the airfoil. The backflow becomes stronger with the increase in AA. The stagnation point also moves down towards the bottom surface from the tip of the airfoil with the increase in AA.
Simulation assessment of the absorber tube of a solar parabolic trough collector using two types of spiral indentations
Authors: Sarangi Asish , Sahoo Sudhansu S. , Mallik Ramesh K.
Published: September 2024

Effective solar energy usage and solar energy gathering have grown in prominence due to the dearth of fossil fuels in recent years. In the current research, the absorber tube of a parabolic trough solar collector having two types of indentations has been considered and numerically simulated. For these studies, a steady heat flux has been considered on the tube. Fluid flow in the tube is subjected to turbulence and for which, the k-RNG turbulence model is utilized. It is revealed that the Nusselt number for absorber tubes with trapezoidal indentations is found to be 72.11, indicating superior thermal efficiency compared to 65.59 for rectangular indentations. However, trapezoidal indentations also result in a higher friction factor leading to a pressure drop of 247.21 Pa than rectangular indentations having a pressure drop of 159.81 Pa. The selection of either rectangular or trapezoidal indentations is contingent upon the particular demands of the application, including factors such as effectiveness, cost, and operational limitations. In situations when it is crucial to minimize energy consumption for fluid flow, the use of a rectangular indentation may be more advantageous. However, if other variables like as heat transfer efficiency take precedence and the extra energy expenditure for pumping can be rationalized, then the trapezoidal indentation may be the preferable option.
Heat transfer analysis of TiO2-H2O based nanofluid flow across a porous stretching sheet with heat source/sink using Response Surface Methodology
Authors: Reshmi V P , Nagaraja K V , Shankara
Published: September 2024

Efforts are focused on optimizing thermal energy control and utilization within the system. The analysis is done on heat transmission characteristics of a TiO2.H2O nanofluid flowing over a stretching sheet with an integrated heat source/sink. Sensitivity analysis is performed using Response Surface Methodology (RSM) to understand heat transfer behaviour effectively. Governing equations are transformed into ordinary differential equations using suitable similarity variables. Mathematical formulation for steady two-dimensional flow of nanofluid in a porous medium along with a stretching sheet is established, and numerical outcomes are optimized using RSM. Influence of porous medium (A), volume fraction (Φ), and heat source/sink (Hs) on Nusselt number (Nu) and skin friction factor (Cf) is analyzed through normal, response surface, and contour plots and it is found that for increasing Hs decreases Nu for higher Φ values.
A Comparison of Classical Nucleation Theory and Thermal Phase Change Based Condensation Models
Authors: Das Sahu Kapil , Sunder Yadav Shyam , Sankar Dasgupta Mani
Published: September 2024

In this work, we perform numerical simulations of the condensation process of CO2 inside a converging-diverging nozzle. We use Ansys Fluent for the simulation work. The real gas properties of CO2 are generated in tabular form (including metastable states) using NIST Refprop. We compare the distribution of physical quantities during the high-speed, compressible flow of CO2 inside a nozzle under the Classical Nucleation Theory (CNT) and the Thermal Phase Change (TPC) models. The CNT model is known to be accurate but computationally expensive while the TPC model is computationally cheaper. We observe that the TPC model predicts a knee in the pressure distribution near the throat of the nozzle while CNT predicts a continuous decrease in the pressure. The two solvers predict slightly different temperature, supercooling and liquid mass fraction values in the diverging part of the nozzle. The compressible, phase change simulations under high speed conditions can be performed quickly with the TPC solver. Overall, the TPC based solver appears to be a reliable alternative to the CNT based model.
Experimental investigation on Counter Flow Double-Pass Solar Air heater with absorber attached with perforated C-shaped Fins.
Authors: Krishna Dutta Ajoy , Kanta Rabha Deva
Published: September 2024

A solar air heater with double-pass and counter flow featuring a perforated C-shaped finned absorber, considering mass flows of 0.041, 0.045 and 0.049 kg/s was investigated experimentally in an outdoor environment. The results of the experiments indicate that solar irradiance, ambient temperature, and the mass flow of air have a noteworthy impact on the efficiency, air temperature rise, and thermal effectiveness of the solar air heater. A noticeable trend indicates a reduction in the efficiency of the heater as the mass flow of air decreases. The mean thermal efficiencies at air mass flows of 0.041, 0.043 and 0.049 kg/s were found to be 77.46, 79.81 and 82.79%, respectively. The temperature rise per unit solar irradiance for the air mass flows of 0.041, 0.043 and 0.049 kg/s were 0.027, 0.026, and 0.025 °C/W-m2, respectively. The thermal effectiveness of the heater was 73.34 72.28 and 70.31% at 0.043, 0.045, 0.049 kg/s air mass flows, respectively. It is noteworthy that the thermal effectiveness declines as the mass flow rates of air decreases.
Quantitative and Comparative evaluation of Titanium Dioxide and Zirconium Dioxide Dental Implants under the effect of average masticatory load: A Computational Approach
Authors: Rani Panda Smita , Chandra Routra Bharat , Chakrabarty Shanta
Published: September 2024

This study investigates the impact of average masticatory loads on dental implants, focusing on titanium dioxide and zirconium dioxide materials due to their corrosion resistance and plaque prevention properties. Utilizing the Finite Element Method, the stresses and deflections in these implant components under an average masticatory load of 100N were evaluated. Locations experiencing the highest loads, and time-dependent stresses and deflections are quantitatively measured to analyze the effect of average masticatory load. The findings provide quantitative insights into how these materials withstand masticatory forces, offering valuable information for dental implant design and durability.