bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical simulation of Oleo-pneumatic Two-phase flow in variable shock absorber
Authors: Du Siyuan , Zhang Changming , Jia Zhiqiang , Zhou Ke
Published: October 2022

In the actual operation of landing gear oil-pneumatic shock absorber, there is a complex gas-liquid two-phase flow problem inside the shock absorber. In this paper, a simplified model of a metering pin variable damping orifice shock absorber is established, and the compression process of the shock absorber is simulated numerically based on CFD method combined with dynamic mesh technology to study the gas-liquid two-phase flow characteristics and the change of oil damping force. The results show that the oil flows out of the damping orifice into the nitrogen cavity in the form of turbulent jet, and the oil and gas phases are mixed and entrained, and the presence of the metering pin significantly affects the flow pattern and flow field structure of the two phases; the damping force increases continuously during the time period of 0-0.02s, and decreases slightly in the late compression period, and the different initial inflation pressures of the nitrogen cavity have little effect on the change of damping force.
Research of an intelligent fire extinguishing device for dense cable passage
Authors: Liu Sanwei , Duan Xiaoli , Huang Fuyong , Duan Jianjia , Zhang DaoYuan , Gong Liang , He Du
Published: October 2022

In recent years, there have been many cable (accessory) burning events in the cable channel of the company, indicating that the fire isolation measures of dense cable channel and cable intermediate joint are still not perfect, and there are still fire risks. In view of the characteristics of dense cable passage, this paper puts forward a design idea of intelligent fire extinguishing device suitable for dense cable passage. It introduces the structure of each module in detail, puts forward the function of the device and fire extinguishing principle, and expects to provide a new technology for the fire prevention and control of cable passage.
A MEMS high g acceleration sensor simulation analysis
Authors: Yang Yujun , Wang Peng , Chen Manlong , Yang Fan , Liang Yingxuan , Chen Fangfang
Published: October 2022

The acceleration sensor with high g value is widely used in a variety of fields, including collision impact, aerospace, and defense security and thus is a key focus in the future. The sensor with a double-ended four-beam structure is investigated in this paper via finite element simulation analysis. The measurement sensitivity of the sensor can be improved by changing the position of the cantilever beam. Furthermore, transverse interference in the X-direction and Y-direction can be eliminated in theory through the layout of piezoresistors and the Wheatstone circuit. The simulation results show that the sensor's sensitivity is 2.6μV/g while its cross-sensitivity in the X-direction and Y-direction is 0%, indicating that the sensor's performance has been substantially improved.
A Single-Phase Switching Diode Cascade Multistandard Inverter Based on H-Bridge
Authors: Luo Xianchao , Hang Ningxiao , Xiao Wei , Huang Baiqiang , Ma Huaiqing
Published: October 2022

Cascaded multistandard inverter is needed in traditional high-voltage occasions, but a large number of electricitys switching devices in cascaded topology make its control complex and can lead to reduced efficiency and increased cost of inverter operation. In my text, a new basic switching diode topology proposed. It contains three switching devices, three electricity diode elements, and three DC voltage source devices with a voltage ratio of 1:1:2. In the way, five correct voltage standards can be output can be generated. Based on the combination of H-bridge topology, a new cascade topology is proposed. They increase the number of voltage standards and can work in asymmetric DC electricity supply. Therefore, different DC voltage source amplitudes can be provided, thereby reducing the number of electrical and electronic components. Compared with other most advanced cascaded topologies, The main advantage of the proposed cascade topology is the reduction where the number of electricity switche, is determined by a reasonable number of DC voltage source and the reduction in cost. At the same time, the rationality and working principle of the proposed topology are discussed, and the corresponding carrier cascade modulation method is proposed. By comparing the export voltage wave with the target waveform, the driving signal of the switch is obtained from the PWM pulse signal. The correctness and feasibility of the topology are verified by matlab2018 / Simulink simulation.
The Virtual Inertia Control of MMC-HVDC Considering the Effect of Active Power Loss of DC Line
Authors: Huang Baiqiang , Yang Ziqi , Hang Ningxiao , Luo Xianchao , Xiao Wei
Published: October 2022

Modular multi-level converter based high-voltage Direct-Current (MMC-HVDC) grid integration is an effective measure to achieve offshore wind power grid integration of large-scale and long-distance. As the offshore wind farms get farther and farther offshore, the active power loss of their submarine DC cables has become a non-negligible part of offshore wind power's participation in frequency regulation. In this paper, on the basis of simulating the inertia of synchronous generator with DC capacitor energy, a virtual inertial control strategy considering the influence of active power loss of DC cable is derived. And, the influence on the frequency stability of the system after considering the active power loss of the DC cable is also analyzed at the same time. Finally, a model of offshore wind power grid-connected through MMC-HVDC is built on MATLAB/Simulink. The simulation results show that the virtual inertia control strategy considering the active power loss of the DC line can effectively improve the frequency stability of the power system.
Online cleaning of massive data in the evaluation of the health status of wind turbines
Authors: Yuan Donghui , Han Yuan , Zhu Yuhui , Wang Yankai , Jun Rong , Qi Yongsheng , Liu Sizhe
Published: October 2022

The SCADA data of wind turbine contains a number of abnormal data, which seriously affects the prediction and evaluation of the health state of the turbine. Therefore, an abnormal data cleaning algorithm is proposed according to the measured wind speed - power and generator speed - power data. In this algorithm, the key SCADA parameters were selected as data cleaning objects based on the combination of the Copula function and the mutual information feature (CMI). After that, an algorithm combining the Copula function and the local outlier factor (Copula-LOF) was proposed to clean the abnormal data and filter out the abnormal data of outliers and stacking points. Finally, the actual operation data of wind turbines are used to verify the algorithm. The experimental results show that the algorithm can effectively identify all kinds of abnormal data and has a good cleaning effect on abnormal data.
Mid-long-term prediction of electrical load based on particle swarm optimization and RBF neural network
Authors: Huang Yifan , Xiong Ziwei , Zhao Yubin , Wang Wei , Xu Xingming
Published: October 2022

Accurate mid-long-term load forecasting is of great significance to power system planning and safe operation. Therefore, this paper proposed a mid-long-term prediction of electrical load based on PSO and RBF neural networks. Based on RBF neural network, the mid-long-term prediction model of electrical load is established, and the prediction parameters of the RBF neural network are iterated by PSO to obtain the optimal parameter value, which is the key to improving the prediction accuracy. The comparison of calculation results shows that it can improve the accuracy of mid-long-term electric load forecasting.
Five-axis toolpath planning for aero-integral blisk cavities
Authors: Shi Congcong , Zhang Xiaojian , Zhang Xu
Published: October 2022

Integral blisks generally made of high-temperature alloys (such as titanium alloys) are important components in aero-engines. During machining, the tool load is large and the tool wear is serious. Because trochoidal milling can maintain a small contact angle between the tool and the workpiece during the cutting process, it is widely used in the processing of complex aviation blisks. However, when the traditional U-shaped trochoidal toolpath or the maximum inscribed trochoidal toolpath is applied, there are high cutting vibration and low efficiency. Therefore, this paper proposes a new five-axis trochoidal side milling strategy, which is suitable for machining more complex three-dimensional cavities by adjusting the shape of the inscribed arc. Different from the traditional trochoidal pattern, the proposed method can generate a spatial UV parameter line-based tool path from a given complex 3D cavity and map it to the machining surface. In addition, a scheme to optimize the tool orientation of the boundary tool is proposed, so that the machine tool motion axis can run smoothly, thus the blisk can be roughened efficiently. Finally, the proposed schemes are verified by computer simulation and physical cutting experiments, and results show the validity and effectiveness.
Modeling and simulation of pure electric vehicle composite power supply
Authors: Zheng Jintang , Fu Qiye , Zhou Heng , Liu Wei
Published: October 2022

In order to solve the problem of high discharge current, serious heating and low service life of pure electric vehicle with single power battery system driving at high power. Design a top-level model of the composite power supply with battery and ultra-capacitor for pure electric vehicles in the simulation software ADVISOR, propose an energy management control strategy based on logic threshold control theory. Based on MATLAB/Simulink environment, set up a logic threshold limit filtering power shunt module and chose the working condition of NEDC for simulation. The results show that, compared to single battery system, a composite power system embedded in the logic threshold control strategy of filtering thought can distributes the power between the battery and the ultra-capacitor more reasonably, effectively improves the peak output power of the battery, avoiding high current charge and discharge of batteries, extends the life of the battery, and improve the vehicle's power and economy.
Simulation Research on Improved Small Signal Model of VSC Converter
Authors: Yang Jie , Li YaXin , Xiao BoYi , Ma Jun , Yi BoNian
Published: October 2022

Small signal model is the basis of stability analysis and control design of VSC-HVDC. In this paper, the small signal model of VSC-MTDC applies to Voltage Source Converters (VSC) in different conditions through theoretical analysis and derivation. The model of ac system can be widely used by choosing d-q synchronous reference frame flexible. Then according to voltage source converter (VSC) modulation principle, the converter model is revised through the coupling mechanism between ac and dc of converter. This article has constructed three kinds of improved small signal models applied to different conditions. By comparing of Electromagnetic transient simulation and the small-signal model simulation, the small-signal model has high accuracy.
Smart Grid Demand-side Response Model Based on Fuzzy Clustering Analysis
Authors: Li Wenwei , Wang Xiaoming , Shi Jun
Published: October 2022

Grid demand-side response forecasting is greatly affected by new energy generation power. Wind power generation and time are irrelevant. Wind power generation brings greater challenges to the grid, so it is necessary to study the problem of wind power generation. An improved fuzzy clustering demand-side response model based on K-means mode division is proposed, in which the number of wind speed modes of the day to be forecasted is determined according to the K-means mode division method. The historical wind speed data with high correlation coefficients are screened out by fuzzy clustering according to different wind speed modes. The experimental test analysis proves that the improved modular partition algorithm proposed in this paper can overcome the shortcomings of fuzzy clustering that can not distinguish the internal differences of data, and has higher prediction accuracy.
H
∞ Robust Frequency Control of Wind Turbine Generators and Electric Vehicles in Isolated grid
Authors: Zhu Longyang , Lin Chuanjie , Li Rong , Li Minyu , Su Xin
Published: October 2022

Wind turbine generators (WTGs) occupy an increasingly larger share in power system. WTGs in isolated grid lead to fluctuation in power and decrease system inertia. To reduce frequency deviation due to power fluctuation or wind speed change, model of WTGs is established based on deloading control. Considering that WTGs will have institutional wear because of frequent frequency regulation, which would short the life of WTGs, a robust frequency control strategy is proposed. WTGs and electric vehicles (EVs) are used in this control strategy. To suppress disturbances due to wind speed and uncertainty of system parameters, a H
∞ robust controller is solved using linear matrix inequality (LMI) methodology. Time-domain simulation results shows that the adopted control methodology can decrease frequency deviation during power fluctuations and wind speed changes.
Research on heat dissipation of a 1.8KW PMSM based on natural cooling and forced air cooling
Authors: Wang Yue , Tong Ningze , Guo Hailun , Chen Yong , Liu Haoran
Published: October 2022

With the development of high precision, high power density, miniaturization, lightweight and integration of the motor, the internal heat generation of the motor increases sharply and the effective heat dissipation space is seriously insufficient. Temperature rise caused by motor loss is the main factor to determine the motor quota. Based on the fluid-solid coupling heat transfer mechanism of Fluent, the temperature distribution characteristics of the motor under natural cooling and forced air cooling were studied in a 1.8KW permanent magnet synchronous motor, and the prototype was made for further experiments. The simulation results were close to the experimental results, and the accuracy was verified.
Simulation research on hydraulic leveling system of vehicle-mounted radar
Authors: Pan Yunping , Zhao Fangpu , Xiao Jun , Wu Ruiqi
Published: October 2022

In this paper, the hydraulic system of vehicle mounted radar leveling is designed. The leveling hydraulic system adopts six-point support structure and realizes high-precision leveling by means of three-pump and electromagnetic directional valve. The hydraulic system is modeled and simulated by AMESim software, and the changes of system pressure, system flow and leg displacement with time at each stage of leveling are analyzed. According to the designed hydraulic leveling system, tests are carried out under actual working conditions. By comparing the test results with the simulation results, the results show that the simulated system pressure and leveling time are 3.3% and 8.9% different from the test system pressure and leveling time respectively.
Study on surface discharge characteristics and design method of large size oil-paper insulation of electrical transformer
Authors: Zhang Shuqi , Yu Xinru , Wu Chao , Yang Lijun , Cheng Huanchao , Deng Junyu
Published: October 2022

When partial discharge occurs in the power transformer, the arc can further develop on the oil-paper interface between high and low potentials, and then form a path, resulting in large-area flashover. This will lead to a wide range of insulation damage, insulation failure, equipment shutdown and even large-scale economic losses. For the insulation damage caused by surface discharge of oil paper insulation, relevant scientific research institutions have carried out a large number of experimental studies. However, limited by the test conditions, the research focuses on the small-size model below 50mm, and mostly adopts the test device of uneven electric field. The research on the “large-size“ of the same scale inside the transformer is still blank. In this study, an oil-paper insulation surface discharge test platform with a large size of 50-150mm is built, the electric field conditions at the oil paper interface during the operation of transformers in engineering are simulated, and the surface discharge test of insulating paperboard is carried out by taking the same sample processing means as the engineering. Combined with the test results, a typical design optimization case of setting along surface corner ring to improve the allowable value of along surface discharge field and enhance along surface insulation margin is proposed. It lays a foundation for enriching the transformer oil-paper insulation design parameter system and improving the transformer oil paper insulation performance and operation reliability.
Electrochemical corrosion resistance of hydrophobic coatings on ZE41A magnesium alloy synthesized by hydrothermal method
Authors: Wang Dingsong , Shi Jixing , Sun Jinhao , Wang Jianxiang , Zhang Fan
Published: October 2022

Two kinds of hydrophobic coatings on ZE41A magnesium alloy are successfully synthesized using hydrothermal method. The surface morphologies, wettability and anti-corrosion properties of hydrophobic coatings are investigated by the method of scanning electron microscopy, X-ray diffraction and electrochemical corrosion tests. Results show that the sample treated in stearic acid ethanol solution with addition of NiSO4 exhibits a morphology possessing large numbers of fine flower-like micro/nano structures, which results in better hydrophobicity and better corrosion resistance.
Study on toughening of Fe based amorphous coatings by ultra high speed laser cladding
Authors: Zhang Jingchun , Wang Yuyue , Niu Qiang , Fan Ruijun , Wu Jianpeng
Published: October 2022

Fe based amorphous alloys have no defects such as grain boundaries and dislocations, with high hardness and high wear resistance. However, due to the limitation of amorphous brittleness and size effect, they have been unable to realize engineering application. Using ultra-high speed laser cladding technology to prepare Fe based amorphous powder into coating can not only give play to its excellent properties, but also avoid the limitations caused by size effect. Therefore, it has broad application prospects and is expected to become a breakthrough in the engineering application of Fe based amorphous alloy. In this paper, we make Fe52.8Cr22.4Mo18.3B2Si1.2C2.1 on 27SiMn by laser cladding, in view of the phenomenon that cracks are easy to occur in the high hardness coating, the optimization scheme of prefabricated transition layer is designed, the Fe based amorphous coating is toughened, and its wear resistance is studied. The results show that the toughening effect of Ni as the transition layer is the best, and the occurrence rate of surface micro cracks of the coating can be reduced to 35%. The microhardness of the coating is about 1200HV0.1, which is 6 times that of the substrate.
Research on Air-floating Gravity Unloading System of Large-scale Inter-mechanisms
Authors: Li Haiyue , Wang Danyu , Li Jun , Yu Haibin , Zheng Shujie , Li Guang , Tong Xuefeng , Yao Di
Published: October 2022

Aiming at the unloading requirements of heavy load, high stiffness and low damping of the upper mechanism during ground separation and unlocking simulation test of a certain mechanism product, a gravity unloading system based on air flotation was developed. The system can not only realize the gravity unloading of the large heavy-duty mechanism, and follow the upper mechanism to rotate at any speed, but also has small rotation resistance and stable movement. It has been verified by experiments that the air-floating gravity unloading system based on the air-floating method can realize 100% gravity unloading of products over 1 ton, and follow the upper mechanism to perform stable rotating motion, and the support deformation of the air-floating ring is better than 0.8um. The rotational resistance torque is better than 0.2Nm. To meet the unloading requirements of high stiffness and low damping of the upper mechanism, the in-depth research on the ground simulation system of the separation and unlocking between the two structures has a certain research reference value.
Effects of Process Parameters on Density of GH5188 High-temperature Alloy after Selective Laser Melting
Authors: Xu Lifeng , Chu Jiaqing , Wang Jingwen , Zhou Yan , Wang Dongsheng
Published: October 2022

GH5188 high-temperature alloy specimens were fabricated by selective laser melting (SLM) and influencing laws of laser power, laser velocity and laser energy density on density of specimens were researched. The results shows that along with the laser energy density increases from 73.02 J/mm3 to 88.18 J/mm3, porosity in specimens decrease and relative density increases from 98.86% to 99.75%. However, as the laser energy density increase further, the density begins to decrease continuously. The main causes that effects relatively density including: the powder is not fused at low energy density, as well as the powder splash and gasification at higher energy density. Neither inadequate nor excessive laser energy density is conducive to improvement of density of specimens. As the increase of laser velocity and laser power, density of specimens increases firstly and then decreases. The variation trend of relative density is similar with that of laser energy density and there are reasonable ranges of laser velocity and laser power. However, influencing laws of laser velocity and laser power on density of specimens are different.
Study on the key features of dynamic compressive fracture strain of Ti-Zr-Nb solid solution alloys through random forest regressor
Authors: Fan Bojian , Liu Xingwei , Si Shengping , Liu Shuang , Xie Ruyue , Liu Jinxu
Published: October 2022

In some specific application fields, dynamic fracture strain regarding as evaluating dynamic properties of Ti-Zr-Nb solid solution alloy have attracted extensive attention. However, the main influence factors of the dynamic strain of alloys were unclear. For the purpose of regulating Ti-Zr-Nb alloys’ dynamic plasticity and clarify main influence factors of the dynamic plasticity of the materials, powder metallurgy, dynamic properties test combined with machine learning were performed. 56 Ti-Zr-Nb alloys were prepared through powder metallurgy and their dynamic compressive fracture strain was tested. Furthermore, optimization of machine learning model and selection of key features for the prediction of dynamic compressive fracture strain were carried out. The prediction accuracy of optimized model was more than 80%, and three key features that significantly influence the dynamic fracture strain were selected and ordered as: VEC>λ>ΔG.
Microstructures of Al coatings prepared through magnetron co-sputtering with microcrystalline Ti doping
Authors: Zhang Maocai , Cui Hongbing , Wang Yu , Na Shihang , Bai Linrui , Xin Bo
Published: October 2022

Sintered NdFeB magnets are being utilised in numerous applications because of the excellent magnetic properties. However, due to its main components are Fe, B and rare earth metals. There is a potential difference between the neodymium rich phase, boron rich phase and the main phase, which was very easy to form a primary battery and cause electrochemical corrosion on the surface of the material. After the materials are easy to be corroded or the components and structures change, the performance of the materials will become weak or even lost, which will affect the service performance and life of the devices or equipment. According to the requirements of surface protection technology for NdFeB magnets, the preparation of protective coating by magnetron sputtering was an efficient means to enhance the corrosion resistance of magnets. Pure Al coating was deficient in microstructure, hardness and corrosion resistance, and the preparation of composite coating by doping co-sputtering had become a development trend. In the current work, AlTi coatings with various Ti contents were prepared from an Al target and a Ti target using direct and radio frequency hybrid magnetron co-sputtering. The surface morphology, microstructure, and elemental compositions of the AlTi coatings were explored through XRD (X-ray diffraction), SEM (scanning electron microscopy), and EDS (energy dispersive spectroscopy). The anticorrosion performances of the AlTi coatings were evaluated by performing electrochemical tests. According to SEM and EDS, the AlTi composite coating was denser and more homogeneous than that of the Al single layer. Furthermore, the results demonstrated that microcrystalline Ti doping reduced the grain size of Al coatings. Therefore, the corrosion current density of the sintered NdFeB magnets plated with Al(120w)/Ti(10w) was approximately more than a hundred times inferior to that of the pure Al layer, and the hardness of AlTi composite coatings also improved.
Effect of pitch on mechanical properties of braided wire rope under winding and traction condition
Authors: Cui Weihua , Song Bao , Fu Chao , Wang Hui
Published: October 2022

In the tension stringing construction process of power transmission and transformation engineering, the braided wire ropes (BWRs) are in the state of winding and stretching when passing through the friction drum. Pitch is an important structural parameter of BWRs, which directly influences the mechanical behaviors under these conditions. Based on the YS9-8×19 wire rope, this project studies the effect of the rope strand pitch on the curvature and winding from both qualitative and quantitative aspects. Qualitative analysis initially explores the effect of the pitch on the mechanical behaviors. Based on the established “rope-wheel” solid model and numerical simulation model, the stress distribution and the variation trend of the maximum equivalent stress corresponding to different pitches in the winding traction state are obtained through the quantitative analyses of the numerical simulations under the same loads with different pitches. The reasonable pitch range of the BWR subjected to traction and bending load is further concluded, to provide the data reference for the manufacture of related wire ropes.
Simulation research on the pre-strike characteristics of SF6 circuit breaker
Authors: Zhou Xiong , Pang Jianyou , Qian Shuaiwei , Pan Ningbo , Chen Jianxi , Huang Yongqiang , Jiang Wei
Published: October 2022

The pre-strike duration of SF6 circuit breaker closing is one of the indicators to measure the ablative state of contacts, obtaining the pre-strike characteristics of SF6 circuit breaker closing is very important to evaluate the electrical life state of circuit breakers. In this paper, the simulation model of the electrical and fluid coupling simulation of the 110kv SF6 circuit breaker is established, and the pre-strike characteristics of the closing process are studied. The results show that the maximum point of the synchronous midfield is always on the surface of the static arc contact. The density of SF6 on the arc-extinguishing chamber is almost constant; the pressure output of the pressure chamber has little effect on the pre-strike voltage curve. Under the phase voltage of 110kv voltage, the duration of the circuit breaker pre-strike duration is 0.9054ms, which is close to the measured value. Results can provide the basis for the actual life circuit life evaluation.
Additive manufacturing of fine-granularity optically-isolated plastic scintillator elements
Authors: Berns S. , Boillat E. , Boyarintsev A. , De Roeck A. , Dolan S. , Gendotti A. , Grynyov B. , Hugon S. , Kose U. , Kovalchuk S. , Li B. , Rubbia A. , Sibilieva T. , Sgalaberna D. , Weber T. , Wuthrich J. , Zhao X.Y.
Published: October 2022

Plastic scintillator detectors are used in high energy
physics as well as for diagnostic imaging in medicine, beam
monitoring on hadron therapy, muon tomography, dosimetry and many
security applications. To combine particle tracking and calorimetry
it is necessary to build detectors with three-dimensional
granularity, i.e. small voxels of scintillator optically isolated
from each other. Recently, the 3DET collaboration demonstrated the
possibility to 3D print polystyrene-based scintillators with a light
output performance close to that obtained with standard production
methods. In this article, after providing a further
characterization of the developed scintillators, we show the first
matrix of plastic scintillator cubes optically separated by a white
reflector material entirely 3D printed with fused deposition
modeling. This is a major milestone towards the 3D printing of the
first real particle detector. A discussion of the results as well
as the next steps in the R&D is also provided.
CONCERTO: readout and control electronics
Authors: Bourrion O. , Hoarau C. , Bounmy J. , Tourres D. , Vescovi C. , Bouly J.-L. , Ponchant N. , Beelen A. , Calvo M. , Catalano A. , Goupy J. , Lagache G. , Macías-Pérez J.-F. , Marpaud J. , Monfardini A.
Published: October 2022

The CONCERTO spectral-imaging instrument was installed at
the Atacama Pathfinder EXperiment (APEX) 12-meter telescope in April
2021. It has been designed to look at radiation emitted by ionised
carbon atoms, [CII], and use the “intensity Mapping” technique to
set the first constraints on the power spectrum of dusty
star-forming galaxies. The instrument features two arrays of 2152
pixels constituted of Lumped Element Kinetic Inductance Detectors
(LEKID) operated at cryogenic temperatures, cold optics and a fast
Fourier Transform Spectrometer (FTS). To readout and operate the
instrument, a newly designed electronic system hosted in five
microTCA crates and composed of twelve readout boards and two
control boards was designed and commissioned. The architecture and
the performances are presented in this paper.
Study of 20-inch PMTs dark count generated large pulses
Authors: Zhang Yu , Wang Zhimin , Li Min , Zhang Yongpeng , Wang Yaoguang , Peng Zhaoyuan , Yang Changgen , Heng Yuekun
Published: October 2022

The main goal of the JUNO experiment is to determine the
neutrino mass ordering with a 20 kt liquid-scintillator
detector. The 20-inch PMT is crucial as one of JUNO key instruments
to realize an excellent energy resolution of at least 3% at
1 MeV. The knowledge on PMT's characterisation and feature is
critical for detector performance understanding. Large pulses from
PMT dark count such as from the flasher or others are one of the
serious concerns for detector noise control. Focusing on the large
pulses from 20-inch PMT dark count, this paper is trying to
investigate the causes by measurements with a muon tagging
system. It is found that the large pules of 20-inch PMT dark count
is contributed mainly from muons hitting the PMT glass, and we have
a preliminary understanding of the results with a simulation based
on Geant4.
Lessons from a regional analysis of forest recovery trajectories in West Africa
Authors: Amani Bienvenu H K , N’Guessan Anny Estelle , Van der Meersch Victor , Derroire Géraldine , Piponiot Camille , Elogne Aka G M , Traoré Karidia , N’Dja Justin K , Hérault Bruno
Published: October 2022

In West Africa, very poorly documented are the recovery trajectories of secondary forests, and even less is known about the origin of the observed variability in recovery rates. To understand the relative importance of local and regional environmental conditions on these trajectories, we inventoried all trees larger than 2.5 cm DBH on 236 plots (0.2 ha), aged from 0 to 45 years plus controls, on eight chronosequences representing the typical regional North-South climatic gradient of West Africa. In a hierarchical Bayesian framework, we modelled recovery trajectories of biodiversity, aboveground biomass and floristic composition and tested the influence of variability in local (plot history, landscape context, remnant trees) and regional (climate and soil) conditions on recovery rates. Our results show that (a) diversity recovers faster than composition and biomass, (b) among the local variables, the number of remnant trees has a positive impact on recovery rates while the duration of agricultural cultivation has a negative impact, and (c) among the regional variables, the high seasonality of precipitation and climate, typical of the dry forests of the northern West African forest zone, leads to faster secondary successions. Our simulation approaches have indicated that poor regional conditions can be counterbalanced by adequate local conditions and vice versa, which argues strongly in favour of a diagnosis that integrates these two aspects in the choice of more or less active technical itineraries for forest restoration.
Reflection groups and the pizza theorem
Authors: Brailov Yu.
Published: October 2022

The classical theorem about cutting a round pizza into 8 pieces with straight cuts passing through an arbitrary internal point and forming angles of 45 degrees says that the total areas of odd and even pieces are equal if those pieces are ordered around the center of cutting. The current paper proposes a generalization of the Pizza theorem to any dimension and discovers a relationship with the finite reflection group of the series

B
n

B_n

.
Overgroups of subsystem subgroups in exceptional groups: nonideal levels
Authors: Gvozdevsky P.
Published: October 2022

In the present paper, a description of overgroups for the subsystem subgroups

E
(
Δ
,
R
)

E(\Delta ,R)

of the Chevalley groups

G
(
Φ
,
R
)

G(\Phi ,R)

over the ring

R
R

, where

Φ
\Phi

is a simply laced root system and

Δ
\Delta

is its sufficiently large subsystem, is almost entirely finished. Namely, objects called levels are defined and it is shown that for any such overgroup

H
H

there exists a unique level

σ
\sigma

with
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper E left-parenthesis sigma right-parenthesis less-than-or-equal-to upper H less-than-or-equal-to upper S t a b Subscript upper G left-parenthesis normal upper Phi comma upper R right-parenthesis Baseline left-parenthesis upper L Subscript max Baseline left-parenthesis sigma right-parenthesis right-parenthesis">

E
(
σ
)
≤
H
≤

Stab

G
(
Φ
,
R
)

⁡
(

L

max

(
σ
)
)

E(\sigma )\le H\le \operatorname {Stab}_{G(\Phi ,R)}(L_{\max }(\sigma ))

, where

E
(
σ
)

E(\sigma )

is an elementary subgroup associated with the level

σ
\sigma

and

L

max

(
σ
)

L_{\max }(\sigma )

is the corresponding subalgebra of the Chevalley algebra. Unlike the previous papers, here levels can be more complicated than nets of ideals.
Homotopic invariance of dihedral homologies for 𝐴_{∞}-algebras with involution
Authors: Lapin S.
Published: October 2022

It is established that the dihedral homologies of involutive

A

∞

A_{\infty }

-algebras are homotopically invariant with respect to the homotopy equivalences of involutive

A

∞

A_{\infty }

-algebras. As a consequence, it is shown that over any field, the dihedral homologies of a topological space are isomorphic to the dihedral homologies of the involutive

A

∞

A_{\infty }

-algebra of homologies for the simplicial group of Kan loops of the original topological space.
Upper estimates of the Morse numbers for the matrix elements of real linear irreducible representations of compact connected simple Lie groups
Authors: Meshcheryakov M.
Published: October 2022

The Morse numbers of spaces of matrix elements for real irreducible linear representations of compact connected simple Lie groups are estimate from above in a variety of ways, in terms of the dimension, the Dynkin index of the representation, the eigenvalues of the invariant Laplace operator, and the volume of the group.
Isomonodromic quantization of the second Painlevé equation by means of conservative Hamiltonian systems with two degrees of freedom
Authors: Suleimanov B.
Published: October 2022

For the three nonstationary Schrödinger equations
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="i italic h over two pi normal upper Psi Subscript tau Baseline equals upper H left-parenthesis x comma y comma minus i italic h over two pi StartFraction partial-differential Over partial-differential x EndFraction comma minus i italic h over two pi StartFraction partial-differential Over partial-differential y EndFraction right-parenthesis normal upper Psi comma">

i
ℏ

Ψ

τ

=
H
(
x
,
y
,
−
i
ℏ

∂

∂
x

,
−
i
ℏ

∂

∂
y

)
Ψ
,

\begin{equation*} i\hbar \Psi _{\tau }=H(x,y,-i\hbar \frac {\partial }{\partial x},-i\hbar \frac {\partial }{\partial y})\Psi , \end{equation*}

solutions are constructed that correspond to conservative Hamiltonian systems with two degrees of freedom whose general solutions can be represented by those of the second Painlevé equation. These solutions of the Schrödinger equations are expressed via fundamental solutions of systems of linear equations arising in the isomonodromic deformations method, the compatibility condition of which is the second Painlevé equation. The constructed solutions of two nonstationary Schrödinger equations are globally smooth. Some of the smooth solutions in question of one of these two equations exponentially tend to zero as

x
2

+

y
2

→
∞

x^2+y^2\to \infty

if the corresponding solutions of linear systems that are used in the method of isomonodromic deformations are compatible on the so-called 1-tronquée solutions of the second Painlevé equation.
Boundary quasi-analyticity and a Phragmén–Lindelöf type theorem in classes of functions of bounded type in tubular domains
Authors: Shamoyan F.
Published: October 2022

A complete description is obtained of the Carleman classes on

R

n

\mathbb {R}^n

such that every function of bounded type in

C

+
n

\mathbb {C}^n_+

whose boundary values belong to the class under study is in fact a member of the corresponding Carleman class in

C

+
n

∪

R

n

\mathbb {C}^n_+\cup \mathbb {R}^n

. Also a refinement of the classical Salinas theorem is obtained, namely: under the conditions of the Salinas theorem on quasi-analyticity, instead of the assumption that a function belongs to the Carleman class in

C

+
n

∪

R

n

\mathbb {C}^n_+\cup \mathbb {R}^n

it suffices that its boundary values on

R

n

\mathbb {R}^n

belong to the Carleman class, and the function is of bounded type in 

C

+
n

\mathbb {C}^n_+

.
Pituitary Volumes Are Reduced in Patients With Alcohol Use Disorder
Authors: Gurok Mehmet Gurkan , Tabara Muhammed Fatih , Koc Mustafa , Saritoy Sumeyra , Baykara Sema , Atmaca Murad
Published: October 2022

Aims

To determine whether there is a difference in pituitary gland volumes in patients with alcohol use disorder compared to healthy people.

Methods

The subjects included in the study consisted of 15 individuals who met the criteria for alcohol use disorder according to the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM 5) diagnostic criteria based on the Structured Clinical Interview for DSM 5 and were admitted to Firat University School of Medicine, Department of Psychiatry, or were hospitalized, and 17 healthy controls. The volumes of pituitary were measured in subjects.

Results

Absolute pituitary gland volumes of patients with alcohol use disorder and healthy controls were compared in the analysis performed using the independent samples t-test. The mean volume of the patient group was significantly smaller than the healthy controls (58.02 ± 7.24 mm3 in patients with alcohol use disorder vs. 83.08 ± 12.11 mm3, P < 0.01), a difference which persisted after controlling for age, gender and total brain size.

Conclusions

Patients with alcohol use disorder in this study had smaller pituitary gland volumes compared to those of healthy control subjects. However, this study has limitations including small sample size and not adjusting for previous or current medication use or current anxiety and depression.
874 Impact of Covid-19 Measures on Surgical Site Infection Rate in Orthopaedic Patients
Authors: Richardson G , Joumah A , Al-Ashqar M , Bakhshayesh P , Kanakaris N
Published: October 2022

Aim

Rate of surgical site infections (SSI) in orthopaedic surgery is low but can have disastrous consequences. The aim of this study was to assess the impact of Covid-19 measures on the rate of SSI and subsequent readmissions in orthopaedic patients.

Method

Retrospective, observational study comparing rates of SSI in orthopaedic patients who underwent surgery prior to the Covid-19 lockdown versus that of patients who underwent surgery during the lockdown period. A total of 1151 patients were identified using electronic clinical records over two different time periods: 3 months pre Covid-19 lockdown (n=680) and 3 months during the Covid-19 lockdown (n=470). Patients were followed up for 1 year following their initial procedure. Primary outcome was readmission for SSI.

Results

The most commonly performed procedures were arthroplasty and manipulation under anaesthesia with 119 in lockdown vs 101 non-lockdown (p=0.001). The readmission rate was higher in the lockdown group with 61 (13%) vs 44 (6.5%) in the non-lockdown group (p <0.001). However, the majority were due to other surgical complications such as dislocations. Interestingly, the SSI rates were very similar with 24 (5%) in lockdown vs 28 (4%) in non-lockdown (p=0.472). Twenty patients (4.2%) required a secondary procedure for their SSI in the lockdown group vs 24 (3.5%) in non-lockdown (p=0.381). Mortality rate was similar at 44 (9.3%) in lockdown vs 61 (9.0%; p=0.836).

Conclusion

Whilst Covid-19 precautions were associated with higher readmission rates, there was no significant difference in rate of SSI between the two groups.
Correcting cardiorespiratory noise in resting-state functional MRI data acquired in critically ill patients
Authors: Chan Suk-Tak , Sanders William R , Fischer David , Kirsch John E , Napadow Vitaly , Bodien Yelena G , Edlow Brian L
Published: October 2022

Resting-state functional MRI is being used to develop diagnostic, prognostic and therapeutic biomarkers for critically ill patients with severe brain injuries. In studies of healthy volunteers and non-critically ill patients, prospective cardiorespiratory data are routinely collected to remove non-neuronal fluctuations in the resting-state functional MRI signal during analysis. However, the feasibility and utility of collecting cardiorespiratory data in critically ill patients on a clinical MRI scanner are unknown. We concurrently acquired resting-state functional MRI (repetition time = 1250 ms) and cardiac and respiratory data in 23 critically ill patients with acute severe traumatic brain injury and in 12 healthy control subjects. We compared the functional connectivity results from two approaches that are commonly used to correct cardiorespiratory noise: (i) denoising with cardiorespiratory data (i.e. image-based method for retrospective correction of physiological motion effects in functional MRI) and (ii) standard bandpass filtering. Resting-state functional MRI data in 7 patients could not be analysed due to imaging artefacts. In 6 of the remaining 16 patients (37.5%), cardiorespiratory data were either incomplete or corrupted. In patients (n = 10) and control subjects (n = 10), the functional connectivity results corrected with the image-based method for retrospective correction of physiological motion effects in functional MRI did not significantly differ from those corrected with bandpass filtering of 0.008–0.125 Hz. Collectively, these findings suggest that, in critically ill patients with severe traumatic brain injury, there is limited feasibility and utility to denoising the resting-state functional MRI signal with prospectively acquired cardiorespiratory data.
A comparative post hoc analysis of finerenone and spironolactone in resistant hypertension in moderate-to-advanced chronic kidney disease
Authors: Agarwal Rajiv , Pitt Bertram , Palmer Biff F , Kovesdy Csaba P , Burgess Ellen , Filippatos Gerasimos , Małyszko Jolanta , Ruilope Luis M , Rossignol Patrick , Rossing Peter , Pecoits-Filho Roberto , Anker Stefan D , Joseph Amer , Lawatscheck Robert , Wilson Daniel , Gebel Martin , Bakris George L
Published: October 2022

Background

Mineralocorticoid receptor antagonists (MRAs) reduce systolic blood pressure (SBP) and increase serum potassium concentration ([K+]). This indirect comparison investigated any differences in SBP-lowering and hyperkalemia risk between finerenone, a nonsteroidal MRA, and the steroidal MRA spironolactone ± a potassium binder.

Methods

In FIDELITY (a pooled analysis of FIDELIO-DKD and FIGARO-DKD), a subgroup of patients with treatment-resistant hypertension (TRH) and chronic kidney disease meeting eligibility criteria of the AMBER trial were identified (FIDELITY-TRH). The main outcomes were mean change in SBP, incidence of serum [K+] ≥5.5 mmol/L and hyperkalemia-associated treatment discontinuation. Results at ∼17 weeks were compared with 12 weeks from AMBER.

Results

In 624 FIDELITY-TRH patients and 295 AMBER patients, the least squares mean change in SBP (mmHg) from baseline was −7.1 for finerenone and −1.3 for placebo {between-group difference −5.74 [95% confidence interval (CI) −7.99 to −3.49], P < .0001} versus −11.7 for spironolactone + patiromer and −10.8 for spironolactone + placebo [between-group difference −1.0 (95% CI −4.4–2.4), P = .58]. The incidence of serum [K+] ≥5.5 mmol/L was 12% for finerenone and 3% for placebo versus 35% with spironolactone + patiromer and 64% with spironolactone + placebo. Treatment discontinuation due to hyperkalemia was 0.3% for finerenone and 0% for placebo versus 7% for spironolactone + patiromer and 23% for spironolactone + placebo.

Conclusions

In patients with TRH and chronic kidney disease compared with spironolactone with or without patiromer, finerenone was associated with a lower SBP reduction and lower risk of hyperkalemia and treatment discontinuation.

Trial Registration: AMBER (NCT03071263), FIDELIO-DKD (NCT02540993), FIGARO-DKD (NCT02545049)
Management of anaemia in French dialysis patients: results from a large epidemiological retrospective study
Authors: Zaoui Philippe , Courivaud Cecile , Rostoker Guy , Choukroun Gabriel , Dubel Laurence , Lorenzo Maria , Harmand Sarah , Menoyo Calonge Victorio
Published: October 2022

Background

Limited real-world data are available in Europe, especially France, regarding the therapeutic management of anaemia in patients with dialysis-dependent chronic kidney disease (DD CKD).

Methods

This retrospective, longitudinal, observational study was based on medical records from the MEDIAL database of not-for-profit dialysis units in France. From January to December 2016, we included eligible patients (≥18 years), with a diagnosis of CKD and receiving maintenance dialysis. Patients with anaemia were followed up for 2 years after inclusion. Patient demographic data, anaemia status, CKD-related anaemia treatments, and treatment outcomes including laboratory test results were evaluated.

Results

Of 1632 DD CKD patients identified from the MEDIAL database, 1286 had anaemia; 98.2% of patients with anaemia were receiving haemodialysis at index date (ID). Of patients with anaemia, 29.9% had haemoglobin (Hb) levels of 10–11 g/dL and 36.2% had levels of 11–12 g/dL at ID. Furthermore, 21.3% had functional iron deficiency and 11.7% had absolute iron deficiency. The most commonly prescribed treatments at ID for patients with DD CKD–related anaemia were intravenous (IV) iron with erythropoietin-stimulating agents (ESAs) (65.1%). Among patients initiating ESA treatment at ID or during follow-up, 347 (95.3%) reached the Hb target of 10–13 g/dL and maintained response within the target Hb range for a median duration of 113 days.

Conclusions

Despite combined use of ESAs and IV iron, duration within the Hb target range was short, suggesting that anaemia management can be further improved.