bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser-induced fluorescence measurements of spatially resolved OH densities in a helium plasma jet interacting with three different targets in the open air
Authors: Cosimi J , Marchal F , Merbahi N , Eichwald O , Gardou J P , Yousfi M
Published: June 2023

The presented research work is devoted to the measurements of the absolute densities of ground state OH radicals in an atmospheric pressure helium plasma jet launched in free air onto three different targets. The OH density is measured by using laser induced fluorescence (LIF). The plasma is generated inside a glass tube by a dielectric barrier discharge powered by a mono-polar pulsed high voltage. Estimation of the absolute density is based on a quantitative analysis of the spectral and temporal component of the LIF signal and does not require any assumption on the densities of colliding species. Based on this analysis, the spatially-resolved density distributions of OH radicals are determined in front of three different targets (metallic, dielectric, and ultra-pure water) placed in the open air at 2 cm from the exit of the glass tube. In order to also investigate the temporal behaviour of the OH densities, and the influence of the gas flow rate and of the amplitude of the voltage-pulse, planar LIF has been performed investigating the fluorescence signal (i) during the intervals of the discharge pulses, (ii) for various gas flow rates, and (iii) as a function of the amplitude of the voltage pulse. In the free jet configuration without a target, the OH densities were determined to be in the order of

10

19

m

−
3

, whereas they increased up to a factor of 10 in contact with a target. The spatial distributions were also influenced by the dielectric properties of the target: in the case of the metallic target, the maximum of the OH density was found to be in the center between the exit of the glass tube and the target, whereas in the case of the dielectric target, the maximum was found to be close to the surface of the target. In the case of ultra-pure water, the densities were equally distributed between the exit of the glass tube and the target. With this work, the influence of a target on the production of OH radicals was demonstrated, which enables the optimisation of the plasma parameters for an efficient production of OH radicals in front of a target with various dielectric properties.
Understanding the nanoscale chemistry of as-received and fast neutron irradiated Nb3Sn RRP® wires using atom probe tomography
Authors: Wheatley L E , Baumgartner T , Eisterer M , Speller S C , Moody M P , Grovenor C R M
Published: June 2023

Atom probe tomography (APT) has been used to study the effect of fast neutron irradiation on the local chemistry of Nb3Sn samples. Two RRP® wires doped with 2 at% Ti were analysed, one in the as-received condition and the other irradiated to a neutron fluence (E > 0.1 MeV) of 2.82 × 1022m−2 in the TRIGA-II reactor. The irradiated sample had a reduced T
c, an increase in F
p, a shift in the peak of the F
p curve suggesting the introduction of secondary point pinning, and an increase in the estimated scaling field B*. APT analysis has shown that polycrystalline Nb3Sn has three distinct regions of composition, near stoichiometry Nb3Sn (low Nb), regions with a higher Nb content than expected in equilibrium Nb3Sn (high Nb) and grain boundaries. The summed composition of these three regions lies within the Nb3Sn phase for both the as-received and irradiated samples. The distinct regions of high Nb Nb3Sn demonstrate incomplete diffusion in the as-received sample, and the reduction in volume of these high Nb regions after irradiation implies significant radiation induced diffusion has occurred. The presence of other features in the atomic-scale chemistry, such as the extent of Cu segregation at grain boundaries, three types of dislocation array, and unreacted Nb nanoparticles, are compared between samples.
Consistent cosmological structure formation on all scales in relativistic extensions of MOND
Authors: Thomas D.B. , Mozaffari A. , Zlosnik T.
Published: June 2023

General relativity manifests very similar equations in different regimes, notably in large scale cosmological perturbation theory, non-linear cosmological structure formation, and in weak field galactic dynamics. The same is not necessarily true in alternative gravity theories, in particular those that possess MONDian behaviour (“relativistic extensions” of MOND). In these theories different regimes are typically studied quite separately, sometimes even with the freedom in the theories chosen differently in different regimes. If we wish to properly and fully test complete cosmologies containing MOND against the ΛCDM paradigm then we need to understand cosmological structure formation on all scales, and do so in a coherent and consistent manner. We propose a method for doing so and apply it to generalised Einstein-Aether theories as a case study. We derive the equations that govern cosmological structure formation on all scales in these theories and show that the same free function (which may contain both Newtonian and MONDian branches) appears in the cosmological background, linear perturbations, and non-linear cosmological structure formation. We show that MONDian behaviour on galactic scales does not necessarily result in MONDian behaviour on cosmological scales, and for MONDian behaviour to arise cosmologically, there will be no modification to the Friedmann equations governing the evolution of the homogeneous cosmological background. We comment on how existing N-body simulations relate to complete and consistent generalised Einstein-Aether cosmologies. The equations derived in this work allow consistent cosmological N-body simulations to be run in these theories whether or not MONDian behaviour manifests on cosmological scales.
Testing the growth rate in homogeneous and inhomogeneous interacting vacuum models
Authors: Borges H.A. , Pigozzo C. , Hepp P. , Baraúna L.O. , Benetti M.
Published: June 2023

In this work we consider a class of interacting vacuum corresponding to a generalised
Chaplygin gas (gCg) cosmology. In particular we analyse two different scenarios at perturbation
level for the same background interaction characterised by the parameter α: (i) matter that
follows geodesics, corresponding to homogeneous vacuum, and (ii) a covariant ansatz for vacuum
density perturbations. In the latter case, we show that the vacuum perturbations are very tiny as
compared to matter perturbations on sub-horizon scales. In spite of that, depending on the value
of the Chaplygin gas parameter α, vacuum perturbations suppress or enhance the matter
growth rate as compared to the case (i). We use Cosmic Microwave Background (CMB), type Ia
supernovae (SNe) and Redshift Space Distortion (RSD) measurements to test the observational
viability of the model. We found that the mean value of our joint analysis clearly favours a
positive interaction, i.e., an energy flux from dark matter to dark energy, with α ≈
0.143 in both cases, while the cosmological standard model, recovered for α = 0, is ruled
out by 3σ confidence level. Noteworthy, the positive value of interaction can alleviate
both the H
0 and S
8 tension for the dataset considered here.
FDA’s role in expediting innovation of bioelectronic implants for vision restoration
Authors: Gabriele Sandrian Michelle , Ng Elvin , Nguyen Tieuvi , Eydelman Malvina
Published: June 2023

Bioelectronic implants for vision restoration are medical devices regulated in the United States by the Food and Drug Administration (FDA). This paper provides an overview of regulatory pathways and related FDA programs for bioelectronic implants for vision restoration, and identifies some of the gaps in the regulatory science of these devices. The FDA recognizes that additional discussion regarding development in this space is needed to further develop bioelectronic implants and ensure that safe and effective technologies are made available to patients with profound vision loss. FDA regularly participates in the Eye and the Chip World Research Congress meetings and continues to engage with important external stakeholders, including through public workshops such as the recent co-sponsored Expediting Innovation of Bioelectronic Implants for Vision Restoration. By participating in forums for discussion of these devices with all stakeholders, especially patients, FDA seeks to encourage advancement of these devices.
Design and Implementation of Complex Tool Quality Traceability System
Authors: Lin Haotian , Zhu Qiang
Published: June 2023

Traditional complex tool manufacturing enterprises have inconsistent data interfaces, low data utilization, and cannot achieve tool quality traceability. In this paper, a tool quality traceability system based on C/S architecture is built, and a tool life cycle database is established according to product requirements, which covers the data content of design, manufacturing, inspection, client and other stages; The data sharing format of multi terminal in complex tool manufacturing process is designed, which can meet the needs of both users and manufacturers of tools; The establishment of the complex tool quality traceability system provides a feasible scheme for big data mining in the manufacturing industry, realizes the data traceability in the whole life cycle of the tool, can quickly locate and analyze the causes of tool quality, forms a data chain with integrity and high inheritance, effectively improves the design cycle and design ability of complex tools, and provides technical support for the high-quality development of the tool manufacturing industry.
Vehicle Braking Stability Analysis Considering Vehicle Structure Parameters Based on CarSim
Authors: Dong Enguo , Li Yajuan , Sun Boli , Zhang Xiaojun
Published: June 2023

Vehicle braking stability performance can improve the safety of vehicle driving during a braking. However, some parameters of vehicle structure impact on the vehicle braking stability, the characteristic law of the relevant parameters on vehicle braking stability is ignored. A simulation model of vehicle is established using the software of CarSim. The vehicle model is included in the driving system, suspension, steering mechanism, braking system. The impact of wheelbase, and the height of centre of vehicle mass on braking stability performance is analysed. The characteristic law of the relevant parameters on vehicle braking stability is concluded. Based on the characteristic law, the ideal vehicle braking stability is obtained by controlling the vehicle braking force of wheel and the steering angle during a braking.
Measurement and Evaluation Method Study of Alignment Deviation of Double-helical Gear
Authors: Xu Weijun , Zhang Yadong , Shen Yunbo , Liu Cheng
Published: June 2023

The alignment deviation of the V-vertex of two symmetrically arranged gears with different rotation directions is a unique geometric parameter of double helical gears, which has an important effect on the vibration, noise, and double helical gear service life. Aiming to more accurately represent the manufacturing accuracy of double helical gears and their transmission performance, this paper proposes the meaning of the v-vertex basis the contact line of tooth surface based on the apex characteristics of double helical gears. First, the mathematical model of tooth flank is established based on gear meshing theory. Secondly, a method for measuring and evaluating the alignment deviation of double helical gear v-vertex (full tooth contact line method) is proposed. Eventually, the validity and convenience of the proposed measurement method are verified by the experiment. Experimental results showed that the total alignment deviation of double helical gears evaluated by the full tooth contact line method is 0.0082 mm, which meets the design requirements in Reference 16. This paper provides a new measurement and evaluation method for the comprehensive and accurate evaluation of double helical gears, which has significant implications for the design and manufacture of high-precision double helical gears.
Research of Non-mechanical Beam Scanning Technology
Authors: Ye Wenyu , Wang Chunyang , Lei Jue , Zhao Jiaojiao , Wei Qinglong
Published: June 2023

Laser beam scanning technology has been widely used in various fields such as LIDAR, photoelectric detection and space optical communication, etc. Mechanical scanning has problems such as inflexibility and low scanning rate. This paper introduces the basic principles of acoustic-optical scanning, electro-optical scanning, optical phased array and MEMS scanning, and analyses the advantages and disadvantages of several scanning methods and the main application scenarios, and finds that the current optical scanning technology is developing towards large scanning angle, high accuracy, fast response and miniaturization, among which the liquid crystal optical phased array and MEMS scanning technology are relatively mature. The scanning angle of the LCD optical phased array can reach ±10°, and the scanning angle of the MEMS can reach 6.6°*4.4°, which has a broad development prospect.
Study on Electrolyte Dissolution Characteristics of GH4169 Super Alloy
Authors: Tang Lin , Xue Runrong , Liu Zhenzhi , Bo Youfeng , Huang Taiqing , Zhou Hezhicheng
Published: June 2023

GH4169 super alloy has a wide application in the field of aeronautics and astronautics, in order to realize the high quality and fast processing of the complex workpieces with electrochemical machining (ECM), we have studied the electrochemical dissolution characteristics of GH4169 super alloy in composite electrolyte, and explored the rule of influence on machining voltage, feed speed, electrolyte pressure for the machining gap (SG), material removal rate (MRR) and surface roughness (Ra). The results showed that under the composite electrolyte of 10%NaCl+16%NaNO3+4%NaClO3, 17.5V machining voltage and the electrolyte pressure 0.8MPa; temperature 30°C, with 1.0mm/min cathode feed speed, achieved high efficiency and high surface quality machining, surface roughness reached to 0.8μm.
Multi-scale Numerical Simulation of Powder Metallurgy Densification Process
Authors: Liu Miao , Cao Yan , Wang Zhijie , Nie Chaorui
Published: June 2023

In order to reduce defects such as pores, gold phases and cracks in powder metallurgy, scholars have studied the densification process of powder metallurgy. Based on the study of the powder metallurgy deformation mechanism, this paper classifies and summarizes the numerical simulation theory and the methods. At present, the numerical simulation of the densification process of powder metallurgy is carried out mainly in macroscopic, mesoscopic and microscopic directions. Macro scale is an application of finite element method based on continuum theory. The meso-scale is an application of the discrete element method based on the discontinuous media theory. Cellular automata simulation is the main numerical simulation method in the microscale. Different modeling theories and methods have their own adaptability and limitations. By combining the numerical simulation theory and the method of various scales, the process of densification of the material can be realized more accurately and accurately.
Research on Aircraft Object Detection Based on Deep Learning
Authors: Liu Qian , Ma YuanKui
Published: June 2023

At present, the hot topic in academia is how to extract information in remote sensing images quickly. According to the existing methods, to identify the aircraft targets in remote sensing images more effectively, the RSOD-Dataset annotated by Wuhan University was selected and constructed into PASCAL VOC format in this paper. Faster R-CNN and YOLOv3 were used to test the dataset respectively, and their underlying network structures are studied and the results are evaluated using four evaluation metrics. It was found that the metrics obtained with YOLOv3 were Pr=94.72%, Re=80.25%, AP=89.45%, and mAP=89.45% while the metrics obtained with Faster R-CNN were Pr=49.00%, Re=68.06%, AP=60.59%, and mAP=60.59%. For the dataset of this paper, YOLOv3 can be used to identify aircraft targets in remote sensing images more effectively.
Establishment of Straight Profile Hourglass Worm under Virtual Reality
Authors: Xiao Bin , Zhu Qiang , Lin Haotian
Published: June 2023

Virtual workpiece is widely used in dynamic simulation and can be imported into the Virtual Gear Measuring Center (VGMC) to be virtually measured. The tooth surface of hourglass worm is complicated, so the dynamic meshing performance is often improved by modification of the tooth surface. The design cycle of traditional tooth surface modification without digital virtual workpiece is long, and the dynamic meshing performance only can be judged by getting meshing spots with sample parts. In this paper, based on the direct digital modeling, the working tooth surface and the non-working tooth surface are processed respectively for the straight profile enveloping worm, and the errors introduced by the turning tool in the modeling process are eliminated. Segmental cutting and inversion methods are proposed to greatly improve the modeling efficiency. By writing software and parameterizing modeling process, the virtual workpiece model of the hourglass worm with controllable accuracy and no holes and redundant faces can be obtained conveniently and quickly. The model can improve the design efficiency and shorten the design cycle.
Manufacturability Analysis and Research of PCB Component Mounting
Authors: Tian Lei , Wang Yixiao , He Chengyu , Mao Minhang , Chen Lulu
Published: June 2023

In the traditional production mode, the disconnection between PCB design and manufacturing leads to many disadvantages such as more design rework, difficult processing, and high cost. To address this issue, this paper achieves manufacturability analysis at the PCB design stage by establishing a manufacturability analysis system for PCB component placement and simulating the placement process of the placement machine on the computer, taking into account the functional and process requirements of PCB board-level circuits simultaneously, so as to facilitate design decisions in the global tendency of the PCB manufacturing system to be optimal.
Condition Monitoring System of Equipment Transportation Process Based on Data Fusion
Authors: Lv Heng , Wang Hongxi , Wang Guanwei
Published: June 2023

In view of the quality and safety problems caused by environmental factors during equipment transportation, a condition monitoring system for equipment transportation process is designed based on STM32. The system combines the positioning module, motion acquisition module, clock module and storage module to collect, screen and store the motion parameters of the equipment during transportation in real time, and collect the position parameters at a fixed time. The system uses the weighted D-S evidence theory to conduct multi data fusion processing for the stored motion parameters, comprehensively evaluate the transportation status of the equipment during transportation, and the GSM communication module sends the results of multi data fusion processing in real time to reduce the amount of data communication. The simulation experiment results show that the system can realize real-time monitoring and storage of effective motion parameters of equipment during transportation, and effectively save storage space; Multi data fusion algorithm is used to comprehensively evaluate the status of the whole process of equipment transportation and communicate in real time.
Multi-field Coupling Analysis of Electrolytic Machining of Magazine Mounts Based on COMSOL
Authors: Wang Mingkai , Fan Qingming , Zhang Chuanyun , Wang Yubian
Published: June 2023

In electrolytic processing, the flow field of the electrolyte, the applied voltage, and the magnetic effect of the current itself have a significant effect on the stability, efficiency, and surface quality of the process. In this paper, the effects of different inlet pressures on the flow rate and different treatment voltages on the current density and magnetic induction strength are investigated by coupling several fields, such as flow, electric and magnetic fields, using COMSOL software. The simulation results show that the flow rate increases with the increase of inlet pressure, and the flow rate increases by 1 m/s for every 0.1 MPa. The current density increases with the increase of processing voltage, but its uniformity decreases, and the magnetic effect of the current itself also influences the magnitude of the current density
Research of Gantry Frames of Different Materials Based on ANSYS Workbench
Authors: Zeng Mingyuan , Cao Yan , Yang Qixin
Published: June 2023

According to the production requirements of a packaging production line in a distillery, this article designed a suction tray gantry with a width of 1922mm, a length of 5000mm, and a height of 940mm using Solidworks software. Through ANSYS Workbench, the performance advantages and disadvantages of the gantry made of structural steel and aluminum alloy under the maximum load of 100Kg required by the enterprise are analyzed. Finally, through the comparison of their stress, total deformation, and total weight, it is concluded that the total weight of the gantry made of aluminum alloy material is about 660kg lighter than that of the gantry made of structural rigid material when the difference between the stress and total deformation is not significant, and the cost is cheaper. Therefore, the aluminum alloy material is finally selected to make the gantry.
Compressor fouling detection by image analysis
Authors: Suman A , Zanini N , Pinelli M
Published: June 2023

Gas turbine fouling is commonly known as responsible for performance degradation in terms of compression ratio and efficiency. The adhesion of micro-sized particles (soil, soot, salt, etc.) caused the modification of the blade shapes and the surface roughness. Both of these two effects determine the modification of the compressor performance over the unit operation. Due to the lack of capability to forecast the fouling intensity, it could be useful to estimate the fouling intensity during the machine overhaul, collecting strategical data by which a specific characterization of a given machine in a given operating site can be done. The present paper proposes and validates a helpful methodology for estimating the deposit intensity by an image analysis procedure. An image-detection technique has been carried out before and after the contamination process, and, using a subtraction process, a quantitative analysis of the fouled regions can be developed. The results show that, with a careful light and camera setup, the intensity of the deposits can be estimated with an acceptable tolerance band, which allows the possibility of collecting quantitative data on compressor deposits during overhaul operations. This generates a valuable starting point for predicting the overtime degradation of the unit and/or estimating the filtration section efficiency.
A new experimental test rig for performance analysis of radial compressors inside innovative heat pumps
Authors: Ferrando M , Reboli T , Purushothaman S , Traverso A , Halbe C
Published: June 2023

Electrification is playing a major role in the industrial and energy sector, with heat pump (HP) market expected to grow significantly in the next future in accordance with the current energy transition phase, which aims to reduce the utilization of fossil fuels for heat production sector. It is therefore of crucial importance to find new ways to increase heat pump performance and reliability, containing maintenance costs. The use of dynamic compressors in HPs makes it possible to combine good performance with high compactness and silent operation, but unlike the volumetric compressor, this equipment could undergo dangerous instability during operation, which can occur in closed-cycle configuration, quite unusual for dynamic compressors. The aim of this paper is to present a new test-rig for stable and unstable performance analysis of dynamic compressors for innovative heat pumps. An in-depth description of the plant and instrumentation system is provided. The performance of the compressor is analyzed for different operating points, with a particular focus on near-surge operation. Experimental uncertainties and their reduction through data reconciliation techniques is thoroughly investigated.
Thermal performance investigation of metal foam heat exchanger for micro-gas turbine
Authors: Chatzi P , Antoniadou A , Efstathiadis T , Kalfas A I
Published: June 2023

This study presents the experimental monitoring of heat transfer performance of metal foams in transient state. Micro gas turbines require a compact recuperator with high effectiveness to achieve higher thermal efficiency. Porous media such as metal and ceramic foams are characterised by high surface-to-volume ratio. They are known to increase heat transfer and potentially can be incorporated in recuperators. Their structure is ideal for thermal management of compact and lightweight applications. The idea is to combine excellent thermal properties of metal foams with turbine gases heat fluxes exploitation, in order to elevate the temperature of a different working fluid such as water or compressed air before it enters the combustor. A novel facility was designed and developed for monitoring heat transfer mechanisms that occur in metal foams. A copper cylinder is filled with metal foam which is heated in transient state by a sudden switch from cold to hot water flow whereas a cold stream cools the device in a crossflow configuration. The study demonstrates a method based on computerisation of true-colour analysis of digital images for surface temperature visualisation using thermochromic liquid crystals (TLC). Results of temperature as well as local and mean heat transfer coefficient were obtained showing that the hot flow inside the foam was more dominant in heat transfer than the cold flow in the empty channel. The method is promising for the evaluation of transient phenomena in a tube that is filled with porous media.
Experimental Analysis of Partial Evaporation Micro-ORC for low-temperature Heat Recovery
Authors: Ottaviano S , Poletto C , De Pascale A , Bianchi M
Published: June 2023

In this paper, we present an experimental assessment of the performance of a partial evaporating organic Rankine cycle (PE-ORC) power system. The system converts low temperature heat into electrical energy, with a power size around 1 kW, thus suitable for micro-generation in the residential sector. Although the test bench was designed for operating with superheated vapour at the expander inlet, it has demonstrated to be able to work with the expansion occurring entirely in two-phase condition. Since the direct measurement of the vapour quality is not possible using the sensors installed in the test rig, the state of the fluid in the two-phase condition is estimated by means of the thermal balance at the heat exchangers, so the thermodynamic cycle can be evaluated. Temperatures of the heat source in the range between 40 °C and 75 °C have been tested, and for each temperature value the vapour quality at the expander inlet has been varied by regulating the feed-pump rotating speed. Experimental data are provided regarding the performance of the overall cycle, of the heat exchangers, of the expander and of the feed-pump. It was observed that the effectiveness of the evaporator and the efficiency of the pump are improved with respect to the operation with superheated vapour at the expander inlet. However, the overall performance is lower, especially due to the high ratio of the pump consumption over the expander produced power, commonly called back work ratio (BWR). The latter, under some boundary conditions, has resulted higher than the unit, meaning that the system is not able to produce net electrical power. The aim of the paper is to identify the design characteristics required by a micro-ORC energy system in order to enhance its performance in the PE operating mode.
PythonDAQ – A Python based measurement data acquisition and processing software
Authors: Jäger D , Gümmer V
Published: June 2023

This paper introduces PythonDAQ, an open-source Python package for measurement data acquisition, visualization, storage, and post-processing. The code is capable of acquiring measurement data from any sensor with digital data output, performs online calculations, and stores the measured and computed data. A client for live data visualization and tools for postprocessing are also contained in the software package. First, the code is introduced explaining the software architecture and the currently implemented features. Then, the usability is demonstrated by an application at the low-speed compressor test rig FRANCC. As last step, comparisons between PythonDAQ and commercial DAQ solutions, as well as the data acquisition software of a major aero-engine manufacturer are made.
Instrumentation Interference in a Transonic Linear Cascade
Authors: Lopes G. , Simonassi L. , Torre A.F.M. , Lavagnoli S.
Published: June 2023

A major challenge when testing high-speed flows in turbomachinery applications concerns instrumentation intrusiveness. The current work exposes the impact of aerodynamic probes, placed upstream and downstream of the testing article, on the aerodynamics of a transonic low-pressure turbine blade investigated in a linear cascade at engine-representative outlet Mach and Reynolds numbers. The effect of a probe placed downstream of the cascade can be perceived as far as to the inlet of the cascade. The quantification of the probe impact is presented on the blade loading as well as on the instrumentation placed upstream and downstream of the cascade used to monitor the operating conditions during testing. It is shown that the presence of the probe can be partially compensated. The impact of this aerodynamic compensation on the cascade loss is reported.
Redesign of a closed-loop high-speed facility to test distortion generators
Authors: Payyappalli Manas , Boufidi Elissavet , Toracchio Riccardo , Fontaneto Fabrizio
Published: June 2023

Aircraft engine architectures are currently in the phase of a change to meet future market demands. Certain such novel architectures force engines to operate under distorted inflow conditions, which are undesirable during flight. It is important to characterize the effect of such inflow distortions in order to understand the impact on the performance of engine components. This paper discusses the design and development of a novel test-facility that has the capability to test combined total pressure and swirl distortion generators under desired flow conditions. The return duct of the high-speed closed-loop compressor rig R4 at the von Karman Institute for Fluid Dynamics (VKI) has been redesigned to incorporate a test-section where distortion generators can be tested and characterized. Thus, a compressor test-rig is modified to act also as a wind tunnel capable of testing distortion generators at engine-like conditions.
Evolution of a five-hole probe calibration near a wall
Authors: Vasseur Adrien , Binder Nicolas , Fontaneto Fabrizio , Champion Jean-Louis
Published: June 2023

Five-hole probes (5HP) are a common tool for measurements of the velocity in turbomachinery studies. In those applications, the spaces are confined, which drives the probes to get close to walls. The proximity of the wall affects the behavior of the 5HP. The wall-related evolution of the calibration of two hemispheric L-shaped 3D printed five-hole probes is investigated in a low speed wind tunnel. 2D Particle Image Velocimetry (PIV) and pressure measurements were carried out. The wall proximity causes the probe to measure that the flow goes away from the wall whereas the boundary layer causes the probe to feel that the flow direction is towards the wall.
Characterizing Atlantic interhemispheric teleconnection established by South American monsoon in austral summer
Authors: Tseng Wan-Ling , Lee Yu-Chi , Wang Yi-Chi , Hsu Huang-Hsiung , Keenlyside Noel
Published: June 2023

This study aims to characterize the interhemispheric teleconnection pattern, which is established by the South America (SA) summer monsoon over the Atlantic Ocean during January and February, and referred it as the Atlantic symmetric pattern (ASP). The ASP is characterized using the leading mode of interannual sea surface temperature (SST) variability of the Southwest Atlantic Ocean, where strong convection-SST coupling occurs. The pattern is manifested as two anomalous cyclonic-anticyclonic-cyclonic circulation trains aligned meridionally over the Atlantic Ocean, with a distinct SST dipole of the Southwest Atlantic Ocean and a tripole of the North Atlantic Ocean. The interhemispheric wave trains of the ASP are excited as a Gill-type response to convective activity in the SA summer monsoon, as confirmed in linear baroclinic model. Complementing previous studies on observed interhemispheric connection in the Atlantic, our findings highlight the importance of characterizing the ASP and its role in linking the South Atlantic SST, the SA summer monsoon, and North Atlantic climate. Further research is warranted to explore the impacts of the ASP on the Northern Hemisphere and its interactions with other climatic modes.
Enzymatic and catalytic behaviour of low-dimensional gold nanomaterials in modular nano-composite hydrogels
Authors: Newham George , Fox Joseph , Moorcroft Samuel C T , Evans Stephen D
Published: June 2023

Inorganic nanoparticles have long been applied as catalysts and nanozymes with exceptional rate constants arising from their large surface areas. While it is understood that high surface area-to-volume ratios and low average atomic coordination are responsible for their exceptional catalytic properties, these facets remain under exploited in the design of gold nanoparticle catalysts and nanozymes. Here we have developed 3D, 2D, and quasi-1D gold nanoparticles for use as catalysts in reducing 4-nitrophenol by sodium borohydride. Each morphology was characterised with transmission electron microscopy and UV–vis absorption spectroscopy, while the highest catalytic activity was achieved when the perimeter-to-surface area, or amount of ‘edge’, was maximised. The particles were then applied as nanozymes in modular nano-composite hydrogels. Independent hydrogel tiles containing either the substrate or catalyst were bonded in stacks, which allowed reagent transport across their interface for the colourimetric detection of hydrogen peroxide. This work presents novel insight into the catalytic activity of low-dimension nanoparticles and their potential application in nanozyme-based diagnostic devices.
A comparative study of machine learning methods for classifying ERP scalp distribution
Authors: Salehzadeh Roya , Soylu Firat , Jalili Nader
Published: June 2023

Objective. Machine learning (ML) methods are used in different fields for classification and regression purposes with different applications. These methods are also used with various non-invasive brain signals, including Electroencephalography (EEG) signals to detect some patterns in the brain signals. ML methods are considered critical tools for EEG analysis since could overcome some of the limitations in the traditional methods of EEG analysis such as Event-related potentials (ERPs) analysis. The goal of this paper was to apply ML classification methods on ERP scalp distribution to investigate the performance of these methods in identifying numerical information carried in different finger-numeral configurations (FNCs). FNCs in their three forms of montring, counting, and non-canonical counting are used for communication, counting, and doing arithmetic across the world between children and even adults. Studies have shown the relationship between perceptual and semantic processing of FNCs, and neural differences in visually identifying different types of FNCs. Approach. A publicly available 32-channel EEG dataset recorded for 38 participants while they were shown a picture of an FNC (i.e., three categories and four numbers of 1,2,3, and 4) was used. EEG data were pre-processed and ERP scalp distribution of different FNCs was classified across time by six ML methods, including support vector machine, linear discriminant analysis, naïve Bayes, decision tree, K-nearest neighbor, and neural network. The classification was conducted in two conditions: classifying all FNCs together (i.e., 12 classes) and classifying FNCs of each category separately (i.e., 4 classes). Results. The support vector machine had the highest classification accuracy for both conditions. For classifying all FNCs together, the K-nearest neighbor was the next in line; however, the neural network could retrieve numerical information from the FNCs for category-specific classification. Significance. The significance of this study is in exploring the application of multiple ML methods in recognizing numerical information contained in ERP scalp distribution of different finger-numeral configurations.
Sorption-enhanced steam reforming of toluene using multifunctional perovskite phase transition sorbents in a chemical looping scheme
Authors: Brody Leo , Rukh Mahe , Cai Runxia , Saberi Bosari Azin , Schomäcker Reinhard , Li Fanxing
Published: June 2023

Sorption-enhanced steam reforming (SESR) of toluene (SESRT) using catalytic CO2 sorbents is a promising route to convert the aromatic tar byproducts formed in lignocellulosic biomass gasification into hydrogen (H2) or H2-rich syngas. Commonly used sorbents such as CaO are effective in capturing CO2 initially but are prone to lose their sorption capacity over repeated cycles due to sintering at high temperatures. Herein, we present a demonstration of SESRT using A- and B-site doped Sr1−x
A’
x
Fe1−y
B’
y
O3−δ
(A’ = Ba, Ca; B’ = Co) perovskites in a chemical looping scheme. We found that surface impregnation of 5–10 mol% Ni on the perovskite was effective in improving toluene conversion. However, upon cycling, the impregnated Ni tends to migrate into the bulk and lose activity. This prompted the adoption of a dual bed configuration using a pre-bed of NiO/γ–Al2O3 catalyst upstream of the sorbent. A comparison is made between isothermal operation and a more traditional temperature-swing mode, where for the latter, an average sorption capacity of ∼38% was witnessed over five SESR cycles with H2-rich product syngas evidenced by a ratio of H2: CO
x
> 4.0. XRD analysis of fresh and cycled samples of Sr0.25Ba0.75Fe0.375Co0.625O3-δ
reveal that this material is an effective phase transition sorbent—capable of cyclically capturing and releasing CO2 without irreversible phase changes occurring.
Optical properties of twisted bilayer graphene with magnetic defects
Authors: Natalin Nikita V , Kundelev Evgeny V , Rukhlenko Ivan D , Tepliakov Nikita V
Published: June 2023

Even when fabricated under ideal conditions twisted bilayer graphene (TBG) inevitably contains various defects which may significantly affect its physical properties. Here we comprehensively analyze the impact of typical point defects, represented by adsorbed hydrogen atoms, on the electronic and optical properties of TBG. It is shown using self-consistent tight-binding Hamiltonians that such point defects make TBG ferromagnetic, and that its ground state comprises a pair of nearly dispersionless spin-polarized energy bands around the Fermi level. Transitions to and from these bands strongly modify the infrared absorption of TBG and result in a sharp low-energy peak in its spectrum. It is also revealed that the adsorption of hydrogen atoms suppresses the circular dichroism of TBG due to the weakening of the electronic coupling between the graphene layers. Our findings will guide future experimental studies on the optical properties of TBG in realistic, impurity-rich environments.
A 3-layered feedforward back-propagation ANN-based SVPWM control for neutral point clamped converter for PV grid integration
Authors: Singh S P , Husain Mohammed Aslam , Minai Ahmad Faiz , Bakhsh Farhad Illahi , Ansari Akhtar Saleem , Khan Ahmad Neyaz , Pandey Yudhishthir
Published: June 2023

Most of the power electronic converters based on the devices such as Silicon Controlled Rectifiers (SCRs) have been broadly utilized in home, business, and modern use in recent years. Despite their many benefits, these power electronic converters have major issues such as pulling harmonic current and the reactive part of the current from the supply, as well as having a highly nonlinear characteristic. The harmonics produced by the current supplied by these nonlinear elements cause voltage distortion at the common coupling point, which is causing problems for the functioning of number of sensitive instruments and other consumer appliances. Artificial Neural Networks (ANN) are a type of Artificial Intelligence (AI) approach that has been applied to improve the efficiency and regulation of the converter. In order to avoid the need for a Digital Signal Processors (DSP) by avoiding the online timing computations for various voltage space vectors in various regions and sectors and produce higher pulse resolution, an ANN-based space vector pulse width modulation (SVPWM) technique is proposed in this paper. The analysis of a 3-layered feedforward back propagation ANN algorithm based SVPWM control for NPC converter used to integrate PV source to grid has been evaluated and found to be better as compared to traditional techniques.
MeGen - generation of gallium metal clusters using reinforcement learning
Authors: Modee Rohit , Verma Ashwini , Joshi Kavita , Deva Priyakumar U
Published: June 2023

The generation of low-energy 3D structures of metal clusters depends on the efficiency of the search algorithm and the accuracy of inter-atomic interaction description. In this work, we formulate the search algorithm as a reinforcement learning (RL) problem. Concisely, we propose a novel actor-critic architecture that generates low-lying isomers of metal clusters at a fraction of computational cost than conventional methods. Our RL-based search algorithm uses a previously developed DART model as a reward function to describe the inter-atomic interactions to validate predicted structures. Using the DART model as a reward function incentivizes the RL model to generate low-energy structures and helps generate valid structures. We demonstrate the advantages of our approach over conventional methods for scanning local minima on potential energy surface. Our approach not only generates isomer of gallium clusters at a minimal computational cost but also predicts isomer families that were not discovered through previous density-functional theory (DFT)-based approaches.
Simulating the filament morphology in electrochemical metallization cells
Authors: Buttberg Milan , Valov Ilia , Menzel Stephan
Published: June 2023

Electrochemical metallization (ECM) cells are based on the principle of voltage controlled formation or dissolution of a nanometer-thin metallic conductive filament (CF) between two electrodes separated by an insulating material, e.g. an oxide. The lifetime of the CF depends on factors such as materials and biasing. Depending on the lifetime of the CF—from microseconds to years—ECM cells show promising properties for use in neuromorphic circuits, for in-memory computing, or as selectors and memory cells in storage applications. For enabling those technologies with ECM cells, the lifetime of the CF has to be controlled. As various authors connect the lifetime with the morphology of the CF, the key parameters for CF formation have to be identified. In this work, we present a 2D axisymmetric physical continuum model that describes the kinetics of volatile and non-volatile ECM cells, as well as the morphology of the CF. It is shown that the morphology depends on both the amplitude of the applied voltage signal and CF-growth induced mechanical stress within the oxide layer. The model is validated with previously published kinetic measurements of non-volatile Ag/SiO2/Pt and volatile Ag/HfO2/Pt cells and the simulated CF morphologies are consistent with previous experimental CF observations.
High Growing Season Temperatures Limit Winter Recovery of Grapevines from Xylella fastidiosa Infection – Implications for Epidemiology in Hot Climates
Authors: Burbank Lindsey , Sisterson Mark S. , Wei Wei , Ortega Brandon , Luna Nathaniel , Naegele Rachel
Published: June 2023

Management of widespread plant pathogens is challenging as climatic differences among crop-growing regions may alter key aspects of pathogen spread and disease severity. Xylella fastidiosa is a xylem-limited bacterial pathogen that is transmitted by xylem sap-feeding insects. Geographic distribution of X. fastidiosa is limited by winter climate, and vines infected with X. fastidiosa can recover from infection when held at cold temperatures. California has a long history of research on Pierce’s disease and significant geographic and climatic diversity among grape-growing regions. This background in combination with experimental disease studies under controlled temperature conditions can inform risk assessment for X. fastidiosa spread and epidemic severity across different regions and under changing climate conditions. California’s grape-growing regions have considerable differences in summer and winter climate. In northern and coastal regions, summers are mild and winters are cool, conditions which favor winter recovery of infected vines. In contrast, in inland and southern areas, summers are hot and winters mild, reducing likelihood of winter recovery. Here, winter recovery of three table grape cultivars (Flame, Scarlet Royal, and Thompson Seedless) and three wine grape cultivars (Sauvignon Blanc, Cabernet Sauvignon, and Zinfandel) were evaluated under temperature conditions representative of the San Joaquin Valley, an area with hot summers and mild winters that has been severely impacted by Pierce’s disease and contains a large portion of California grape production. Mechanically inoculated vines were held in the greenhouse under one of three warming treatments to represent different seasonal inoculation dates prior to being moved into a cold chamber. Winter recovery under all treatments was generally limited but with some cultivar variation. Given hot summer temperatures of many grape-growing regions worldwide, as well as increasing global temperatures overall, winter recovery of grapevines should not be considered a key factor limiting X. fastidiosa spread and epidemic severity in the majority of cases.
Summarized Distribution of the Southern Root-Knot Nematode, Meloidogyne incognita, in Field Crops in the United States
Authors: Faske Travis R. , Mueller John , Becker J. Ole , Bernard Ernest C. , Bradley Carl , Bond Jason , Desager Johan , Eisenback Jonathan , Grabau Zane , Hu Jiahuai , Kemerait Robert , Koehler Alyssa , Lawrence Kathy , Mehl Hillary , Rudolph Rachel E. , Sikora Edward J. , Thomas Steve , Walker Nathan , Wheeler Terry , Wrather Allen J. , Ye Weimin , Zhang Lei
Published: June 2023

The southern root-knot nematode, Meloidogyne incognita (Kofoid and White, 1919) Chitwood, 1949, is one of the most important, yield-limiting pathogens of agronomic and vegetable crops in the United States and worldwide. It was first reported on cotton ( Gossypium hirsutum L.) in Alabama in the United States. Since then, it has been reported in many states across the United States. These reports include detections in greenhouses, nurseries, or home gardens but do not provide information on where this species persists from year to year in field soils. Furthermore, these reports do not provide distribution information within each state in individual counties. This report summarized the distribution of M. incognita on field crops (e.g., agronomic and vegetable crops) by county for each state across the continental United States.