Integrated Experimental and Simulation Investigation of Breakdown Voltage Characteristics Across Electrode Configurations in SF_(6) Circuit Breakers

This study investigates the breakdown voltage characteristics in sulfur hexafluoride(SF6)circuit breakers,employing a novel approach that integrates both experimental investigations and finite element simulations.Utilizing a sphere-sphere electrode configuration,we meticulously measured the relationship between breakdown voltage and electrode gap distances ranging from 1 cm to 4.5 cm.Subsequent simulations,conducted using COMSOL Multiphysics,mirrored the experimental setup to validate the model’s accuracy through a comparison of the breakdown voltage-electrode gap distance curves.The simulation results not only aligned closely with the experimental data but also allowed the extraction of detailed electric field strength,electric potential contours,and electric current flow curves at the breakdown voltage for gap distances extending from 1 to 4.5 cm.Extending the analysis,the study explored the electric field and potential distribution at a constant voltage of 72.5 kV for gap distances between 1 to 10 cm,identifying the maximum electric field strength.A comprehensive comparison of five different electrode configurations(sphere-sphere,sphere-rod,sphere-plane,rod-plane,rod-rod)at 72.5 kV and a gap distance of 1.84 cm underscored the significant influence of electrode geometry on the breakdown process.Moreover,the research contrasts the breakdown voltage in SF6 with that in air,emphasizing SF6’s superior insulating properties.This investigation not only elucidates the intricate dynamics of electrical breakdown in SF6 circuit breakers but also contributes valuable insights into the optimal electrode configurations and the potential for alternative insulating gases,steering future advancements in high-voltage circuit breaker technology.

基于合成数据集的多目标识别与6-DoF位姿估计

多目标识别及六自由度(6-DoF)位姿估计是实现物料无序堆放状态下机器人自动分拣的关键。近年来,基于深度神经网络的方法在目标识别及位姿估计领域受到广泛关注,但此类方法依赖大量训练样本,而样本的采集及标注费时费力,限制了其实用性。其次,当成像条件差、目标相互遮挡时,现有位姿估计方法无法保证结果的可靠性,进而导致抓取失败。为此,文中提出了一种基于合成数据样本的目标识别、分割及位姿估计方法。首先,以目标对象的3维(3D)几何模型为基础,利用3D图形编程工具生成虚拟场景的多视角RGB-D合成图像,并对生成的RGB图像及深度图像分别进行风格迁移和噪声增强,从而提高合成数据的真实感,以适应真实场景的检测需要;接着,利用合成数据集训练YOLOv7-mask实例分割模型,运用真实数据进行测试,结果验证了该方法的有效性;然后,以分割结果为基础,基于ES6D目标位姿估计模型,提出了一种在线姿态评估方法,以自动滤除严重失真的估计结果;最后,采用基于主动视觉的位姿估计校正策略,引导机械臂运动到新的视角重新检测,以解决因遮挡而导致位姿估计偏差的问题。在自行搭建的6自由度工业机器人视觉分拣系统上进行了实验,结果表明,文中提出的方法能较好地适应复杂环境下工件的识别与6-DoF姿态估计要求。

6-DOFs机器臂在位置模式下追随运动意图的研究

为了使脑卒中患者在主动康复中能够得到准确、实时、稳定的识别效果,本研究提出了基于6-DOFs协作机器人作为一种康复运动设备。患者的运动意图通过其手与机器臂末端的六维力传感器作用的程度与方向来捕捉,控制系统则通过解析出的运动意图实现机器臂末端运动方向与速度的设置和驱动。运动意图主要由运动方向和运动程度两个指标表达,前者由力传感器各分力的合力方向确定,后者由合力的大小确定,同时还要检测合力与TCP所在轨迹点处切线方向的夹角,最终确定出机器臂末端沿轨迹运动的速度。

CAS-ESM2.0 Successfully Reproduces Historical Atmospheric CO_(2) in a Coupled Carbon−Climate Simulation

The atmospheric carbon dioxide(CO_(2))concentration has been increasing rapidly since the Industrial Revolution,which has led to unequivocal global warming and crucial environmental change.It is extremely important to investigate the interactions among atmospheric CO_(2),the physical climate system,and the carbon cycle of the underlying surface for a better understanding of the Earth system.Earth system models are widely used to investigate these interactions via coupled carbon-climate simulations.The Chinese Academy of Sciences Earth System Model version 2(CAS-ESM2.0)has successfully fixed a two-way coupling of atmospheric CO_(2)with the climate and carbon cycle on land and in the ocean.Using CAS-ESM2.0,we conducted a coupled carbon-climate simulation by following the CMIP6 proposal of a historical emissions-driven experiment.This paper examines the modeled CO_(2)by comparison with observed CO_(2)at the sites of Mauna Loa and Barrow,and the Greenhouse Gases Observing Satellite(GOSAT)CO_(2)product.The results showed that CAS-ESM2.0 agrees very well with observations in reproducing the increasing trend of annual CO_(2)during the period 1850-2014,and in capturing the seasonal cycle of CO_(2)at the two baseline sites,as well as over northern high latitudes.These agreements illustrate a good ability of CAS-ESM2.0 in simulating carbon-climate interactions,even though uncertainties remain in the processes involved.This paper reports an important stage of the development of CAS-ESM with the coupling of carbon and climate,which will provide significant scientific support for climate research and China’s goal of carbon neutrality.

The Arctic Sea Ice Thickness Change in CMIP6’s Historical Simulations

This study assesses sea ice thickness(SIT)from the historical run of the Coupled Model Inter-comparison Project Phase 6(CMIP6).The SIT reanalysis from the Pan-Arctic Ice Ocean Modeling and Assimilation System(PIOMAS)product is chosen as the validation reference data.Results show that most models can adequately reproduce the climatological mean,seasonal cycle,and long-term trend of Arctic Ocean SIT during 1979-2014,but significant inter-model spread exists.Differences in simulated SIT patterns among the CMIP6 models may be related to model resolution and sea ice model components.By comparing the climatological mean and trend for SIT among all models,the Arctic SIT change in different seas during 1979-2014 is evaluated.Under the scenario of historical radiative forcing,the Arctic SIT will probably exponentially decay at-18%(10 yr)-1 and plausibly reach its minimum(equilibrium)of 0.47 m since the 2070s.

The Warm Arctic-Cold Eurasia Pattern and Its Key Region in Winter in CMIP6 Model Simulations

An enhanced Warm Arctic-Cold Eurasia(WACE)pattern has been a notable feature in recent winters of the Northern Hemisphere.However,divergent results between model and observational studies of the WACE still remain.This study evaluates the performance of 39 climate models participating in the Coupled Model Intercomparison Project Phase 6(CMIP6)in simulating the WACE pattern in winter of 1980-2014 and explores the key factors causing the differences in the simulation capability among the models.The results show that the multimodel ensemble(MME)can better simulate the spatial distribution of the WACE pattern than most single models.Models that can/cannot simulate both the climatology and the standard deviation of the Eurasian winter surface air temperature well,especially the latter,usually can/cannot simulate the WACE pattern well.This mainly results from the different abilities of the models to simulate the range and intensity of the warm anomaly in the Barents Sea-Kara seas(BKS)region.Further analysis shows that a good performance of the models in the BKS area is usually related to their ability to simulate location and persistence of Ural blocking(UB),which can transport heat to the BKS region,causing the warm Arctic,and strengthen the westerly trough downstream,cooling central Eurasia.Therefore,simulation of UB is key and significantly affects the model’s performance in simulating the WACE.

Micro-Scale Motion Precision Simulation Method for a New-Type 6-DOF Micro-Manipulation Robot

A new 6-DOF micro-manipulation robot based on 3-PPTTRS parallel mechanisms in combination with flexure hinges is proposed. The design principle of the mechanism is introduced, and the kinematics analysis method based on differentiation is used to get the (inverse) kinematics equations. Then a micro-scale motion precision simulation method is proposed according to finite element analysis (FEA), and the prediction of robot’s motion precision in design phase is realized. The simulation result indicates that the 6-DOF micro-manipulation robot can meet the design specification.

Ⅳ型储氢气瓶内衬材料聚酰胺6氢渗透行为的分子模拟研究

采用分子模拟方法,在不同温度(30、40、60、80℃)和压力(82、87.5、98、103 MPa)条件下,研究氢气在聚合物材料聚酰胺6(PA6)中的渗透性,并分析了氢气的渗透机理。结果表明,温度升高时,吸附热和自由体积分数逐渐增加,热运动加剧,分子运动空间增大,氢气在PA6中的溶解度系数、扩散系数以及渗透系数均呈增大趋势。在压力为103 MPa时,升高温度对渗透系数的影响最大,增加了88.3%。随着压力增大,氢气与PA6分子链之间的相互作用减小,自由体积分数减小,所以氢气在PA6中的溶解度系数、扩散系数以及渗透系数均呈下降趋势。在温度为60℃时,压力对渗透系数影响最显著,降低了38.6%。氢气在PA6中的渗透机理包括在低势能区的聚集性吸附过程,和在自由体积处形成的空穴内振动-空穴间跃迁的扩散过程,温度升高时,氢气分子运动变得活跃,有更多的空穴间跳跃次数,压力升高时,变化相反。

6-DOF机械臂运动学分析和验证

为了实现6-DOF机械臂末端的运动控制,利用改进D-H方法推导了机械臂的正运动学齐次变换矩阵,基于齐次变换矩阵,推导出了机械臂的四组运动学逆解,针对运动控制过程中逆解的选取问题,提出了一种基于机械臂初始角的逆解选取方法,并根据解的特性推导出了初始角的可选范围;通过matlab机器人工具箱仿真验证了机器人正逆解以及逆解选取方法的正确性,利用twincat3-机械臂控制系统进行实验,进一步验证了逆解选取方法的正确有效。

Simulation of type selection for 6-high cold tandem mill based on shape control ability

A theoretical method for selecting strip rolling mill type that considered shape control ability was established using the figure alteration range that was worked by the alteration track of vector expressing strip's cross section (crown) to express the shape control ability of rolling mill. With the mathematical models and simulation software that were developed by the authors' own models, four types of mills were aimed, including HCM (6-high middle rolls shift type HC (high crown) -mill), HCMW (6-high middle rolls and work rolls shift type HC-mill), UCM (6-high middle rolls shift type HC-mill with middle roll bender) and UCMW (6-high middle rolls and work rolls shift type HC-mill with middle roll bender), and the shape and crown control ability of every mill type was analyzed and compared. An appropriate arrangement mode of tandem mill was brought forward. The results show that UCMW mill is a perfect choice for controlling shape and crown, and the area of control characteristics curve of UCMW (or UCM) is twice than that of HCM, but UCM mill is also a good choice for its simple frame. In other word, the shape and crown controlling ability of UCMW mill is better than that of UCM mill, but the frame of UCM mill is simpler than that of UCMW mill. As for the final type of mill, should be synthetically decided by thinking over fund and equipment technology.

Improvement of Soil Moisture Simulation in Eurasia by the Beijing Climate Center Climate System Model from CMIP5 to CMIP6

This study provides a comprehensive evaluation of historical surface soil moisture simulation(1979-2012)over Eurasia at annual and seasonal time scales between two medium-resolution versions of the Beijing Climate Center Climate System Model(BCC-CSM)—one that is currently participating in phase 6 of the Coupled Model Intercomparison Project(CMIP6),i.e.,BCC-CSM2-MR,and the other,BCC-CSM1.1m,which participated in CMIP5.We show that BCC-CSM2-MR is more skillful in reproducing the climate mean states and standard deviations of soil moisture,with pattern correlations increased and biases reduced significantly.BCC-CSM2-MR performs better in capturing the first two primary patterns of soil moisture anomalies,where the period of the corresponding time series is closer to that of reference data.Comparisons show that BCC-CSM2-MR performs at a high level among multiple models of CMIP6 in terms of centered pattern correlation and“amplitude of variation”(relative standard deviation).In general,the centered pattern correlation of BCC-CSM2-MR,ranging from 0.61 to 0.87,is higher than the multi-model mean of CMIP6,and the relative standard deviation is 0.75,which surmounts the overestimations in most of the CMIP6 models.Due to the vital role played by precipitation in land-atmosphere interaction,possible causes of the improvement of soil moisture simulation are further related to precipitation in BCC-CSM2-MR.The results indicate that a better description of the relationship between soil moisture and precipitation and a better reproduction of the climate mean precipitation by the model may result in the improved performance of soil moisture simulation.

The CMIP6 Historical Simulation Datasets Produced by the Climate System Model CAMS-CSM

This paper describes the historical simulations produced by the Chinese Academy of Meteorological Sciences(CAMS)climate system model(CAMS-CSM),which are contributing to phase 6 of the Coupled Model Intercomparison Project(CMIP6).The model description,experiment design and model outputs are presented.Three members’historical experiments are conducted by CAMS-CSM,with two members starting from different initial conditions,and one excluding the stratospheric aerosol to identify the effect of volcanic eruptions.The outputs of the historical experiments are also validated using observational data.It is found that the model can reproduce the climatological mean states and seasonal cycle of the major climate system quantities,including the surface air temperature,precipitation,and the equatorial thermocline.The long-term trend of air temperature and precipitation is also reasonably captured by CAMS-CSM.There are still some biases in the model that need further improvement.This paper can help the users to better understand the performance and the datasets of CAMS-CSM.

Two Improvements on Numerical Simulation of 2-DOF Vortex-Induced Vibration with Low Mass Ratio

Till now, there have been lots of researches on numerical simulation of vortex-induced vibration. Acceptable results have been obtained for fixed cylinders with low Reynolds number. However, for responses of 2-DOF vortex-induced vibration with low mass ratio, the accuracy is not satisfactory, especially for the maximum amplitudes. In Jauvtis and Williamson＇s work, the maximum amplitude of the cylinder with low mass ratio m＊=2.6 can reach as large as 1.5D to be called as the ＂super-upper branch＂, but from current literatures, few simulation results can achieve such value, even fail to capture the upper branch. Besides, it is found that the amplitude decays too fast in the lower branch with the RANS-based turbulence model. The reason is likely to be the defects of the turbulence model itself in the prediction of unsteady separated flows as well as the unreasonable setting of the numerical simulation parameters. Aiming at above issues, a modified turbulence model is proposed in this paper, and the effect of the acceleration of flow field on the response of vortex-induced vibration is studied based on OpenFOAM. By analyzing the responses of amplitude, phase and trajectory, frequency and vortex mode, it is proved that the vortex-induced vibration can be predicted accurately with the modified turbulence model under appropriate flow field acceleration.

冷大气压等离子体诱导的交变电场对白细胞介素-6结构及功能的影响

冷大气压等离子体(cold atmospheric plasma,CAP)由于其具有“选择性”杀伤癌细胞的效果,而被认为是一种极具潜力的癌症治疗手段.CAP可以通过降低关键炎症因子白细胞介素-6(interleukin-6,IL-6)的表达,抑制肿瘤炎症反应并激活免疫系统.然而CAP携带的强交变电场对IL-6构象及功能的影响仍缺乏了解.本文采用分子动力学方法,模拟了不同频率及强度的交变电场对IL-6构象及其与受体对接过程的影响.结果表明,当电场频率小于30 MHz且电场强度大于0.5 V/nm时,IL-6的平均偶极矩增大,长螺旋间维持稳定的盐桥断裂,α螺旋数量减少,从而影响了IL-6与其受体的结合,对其发挥正常生物效应机制产生潜在影响.本文从微观层面上解释了CAP诱导的电场通过IL-6影响相关生物学效应的内部相互作用机制,并为实际应用CAP治疗肿瘤炎症的参数选取、探索有效的癌症治疗策略提供重要的理论依据.

Finite element simulation of real cavity closure in cast Ti6Al4V alloy during hot isostatic pressing

The healing behavior of shrinkage cavity inside the cast Ti6Al4V alloy during hot isostatic pressing(HIP)was investigated experimentally by interrupted hot isostatic pressing tests.The X-ray micro computed tomography was used to record the morphology changes before and after hot isostatic pressing.The two-dimensional geometry obtained by the microCT scan was used in simulation to study the evolution of the real shrinkage cavity during hot isostatic pressing.Shrinkage cavities,shrinkage porosity and small gas pores can be effectively eliminated under proper HIP conditions.The two-dimensional morphology in the simulation results agrees well with the experimental results.This study reveals that plastic deformation,creep and diffusion are the main mechanisms of cavity closure during hot isostatic pressing.In addition,the simplified elliptical pores with aspect ratios at different positions were used to replace the real pores to further study the factors affecting the position of dimples after HIP by simulation.It is found that the position of the dimples mainly depends on the aspect ratio of the elliptical pore and the distance between the pore surface and the external surface of the geometric model.

CAS FGOALS-f3-L Large-ensemble Simulations for the CMIP6 Polar Amplification Model Intercomparison Project

Large-ensemble simulations of the atmosphere-only time-slice experiments for the Polar Amplification Model Intercomparison Project(PAMIP)were carried out by the model group of the Chinese Academy of Sciences(CAS)Flexible Global Ocean-Atmosphere-Land System(FGOALS-f3-L).Eight groups of experiments forced by different combinations of the sea surface temperature(SST)and sea ice concentration(SIC)for pre-industrial,present-day,and future conditions were performed and published.The time-lag method was used to generate the 100 ensemble members,with each member integrating from 1 April 2000 to 30 June 2001 and the first two months as the spin-up period.The basic model responses of the surface air temperature(SAT)and precipitation were documented.The results indicate that Arctic amplification is mainly caused by Arctic SIC forcing changes.The SAT responses to the Arctic SIC decrease alone show an obvious increase over high latitudes,which is similar to the results from the combined forcing of SST and SIC.However,the change in global precipitation is dominated by the changes in the global SST rather than SIC,partly because tropical precipitation is mainly driven by local SST changes.The uncertainty of the model responses was also investigated through the analysis of the large-ensemble members.The relative roles of SST and SIC,together with their combined influence on Arctic amplification,are also discussed.All of these model datasets will contribute to PAMIP multi-model analysis and improve the understanding of polar amplification.

Molecular dynamics simulation of the material removal in the scratching of 4H-SiC and 6H-SiC substrates

Single crystal silicon carbide(SiC)is widely used for optoelectronics applications.Due to the anisotropic characteristics of single crystal materials,the C face and Si face of single crystal SiC have different physical properties,which may fit for particular application purposes.This paper presents an investigation of the material removal and associated subsurface defects in a set of scratching tests on the C face and Si face of 4H-SiC and 6H-SiC materials using molecular dynamics simulations.The investigation reveals that the sample material deformation consists of plastic,amorphous transformations and dislocation slips that may be prone to brittle split.The results showed that the material removal at the C face is more effective with less amorphous deformation than that at the Si face.Such a phenomenon in scratching relates to the dislocations on the basal plane(0001)of the SiC crystal.Subsurface defects were reduced by applying scratching cut depths equal to integer multiples of a half molecular lattice thickness,which formed a foundation for selecting machining control parameters for the best surface quality.

Atomic Scale Computer Simulation for Early Precipitation Process of Ni75Al6Vi9 Alloy

The atomic scale computer simulation for initial precipitation mechanism of Ni75Al6V19 alloy was carried out for the first time by employing the microscopic diffusion equation. The initial precipitation process was invest igated throughsimulating the atomic pictures and calculating the order parameters of the two kinds of ordered phases. Simulationresults show that the γ′ordered phase precipitated earlier than θ ordered phase by congruent ordering+spinodal decomposition mechanism and thus produced a nonstoicheometric γ′ single ordered phase. Then, the nonstoichiometricθ phase precipitated by a non-classical nucleation and growth mechanism at the APBS of γ′ phase.

玻纤增强PA6焊机外壳性能的影响因素数值模拟

深入探讨了玻璃纤维增强聚酰胺6在焊机外壳应用中的性能表现,并基于ANSYS软件平台,进行了静力学仿真和落球冲击仿真分析,旨在揭示玻纤含量、玻纤长径比以及玻纤取向等关键参数对焊机外壳性能的影响。静力学分析显示,当外壳承受2500 N的拉力时,玻纤含量的增加对焊机外壳应力强度的影响较小,但能够降低了外壳变形程度。当玻纤质量分数超过25%时,等效应力趋于稳定(约51 MPa)。此外,玻纤的取向对焊机外壳性能具有显著影响。当纤维沿X轴和Z轴取向且各占50%时(方向向量为a2),外壳的等效应力达54.6 MPa,同时变形量最小,仅为0.5 mm,这一性能与玻纤质量分数为40%的外壳相当。而玻纤长径比的增加对等效应力的影响并不显著,但有助于减少变形。进一步,通过落球冲击分析发现,随着玻纤含量的增加,外壳的等效应力逐渐增大,变形逐渐减小,这一趋势与静力学分析结果高度一致。当玻纤质量分数低于20%时,焊机外壳在冲击下易出现破裂;然而,当玻纤质量分数为20%~35%时,外壳表现出了优异的冲击性能,未出现开裂现象。

Magnetic properties of La2CuMnO6 double perovskite ceramic investigated by Monte Carlo simulations

We present a theoretical study of the magnetic properties of the lanthanum copper manganate double perovskite La2CuMnO6 ceramic,using Monte Carlo simulations.We analyze and discuss the ground state phase diagrams in different planes to show the effect of every physical parameter.Based on the Monte Carlo simulations,which combine Metropolis algorithm and Ising model,we explore the thermal behavior of the total magnetization and susceptibility.We also present and discuss the influence of physical parameters such as the external magnetic field,the exchange coupling interactions between magnetic atoms,and the exchange magnetic field on the magnetization of the system.Moreover,the critical temperature of the system is about Tc=70 K,in agreement with the experimental value.Finally,the hysteresis loops of La2CuMnO6 are discussed.