Data-driven optimization study of the multi-relaxation-time lattice Boltzmann method for solid-liquid phase change

Sharp phase interfaces and accurate temperature distributions are important criteria in the simulation of solid-liquid phase changes.The multi-relaxation-time lattice Boltzmann method(MRT-LBM)shows great numerical performance during simulation;however,the value method of the relaxation parameters needs to be specified.Therefore,in this study,a random forest(RF)model is used to discriminate the importance of different relaxation parameters to the convergence,and a support vector machine(SVM)is used to explore the decision boundary of the convergent samples in each dimensional model.The results show that the convergence of the samples is consistent with the sign of the decision number,and two types of the numerical deviations appear,i.e.,the phase mushy zone and the non-physical heat transfer.The relaxation parameters chosen on the decision boundary can further suppress the numerical bias and improve numerical accuracy.

Seismic tomography of Yunnan region using short-period surface wave phase velocity

利用云南数字地震台网23个台站记录的短周期(1～18s)面波资料，用双台窄带通滤波互相关方法，测定了在209条路径上的基阶瑞利波相速度频散曲线，并通过层析成像反演得到各周期的相速度分布图象．给出了沿24°N，25°N，26°N及27°N和100．5°E的相速度频散剖面图．结果表明：云南地区的相速度分布图象具有强烈的横向变化，短周期段的相速度分布与沉积层厚度密切相关，中甸、丽江东部区域在约25km深度存在着明显的低速层，而畹町、云县、思茅一带在该深度范围是一明显的大面积高速区域．小江断裂与红河断裂围成的川滇菱形块体南段为低相速度区域．云南地区强震震中位置主要分布在相速度高速与低速过渡的区域．

Seismic tomography of Yunnan region using short-period surface wave phase velocity

The data of short-period (1~18 s) surface waves recorded by 23 stations belonging to the digital seismic network of Yunnan Province of China are used in this paper. From these data, the dispersion curves of phase velocities of the fundamental mode Rayleigh wave along 209 paths are determined by using the two-station narrowband filtering cross-correlation method. Adopting tomography method, the distribution maps of phase velocities at various peri-ods in Yunnan region are inverted. The maps of phase velocities on profiles along 24N, 25N, 26N, 27N and 100.5E and the distribution maps of phase velocities at 3 periods in the study region are given. The results show that the phase velocity distribution in Yunnan region has strong variations in horizontal direction, and the phase velocity distribution in short-period range is closely related to the thickness of sedimentary layers in the shallow crust. The phase velocity in southern part of the Sichuan-Yunnan rhombic block encircled by the Honghe fault and Xiaojiang fault is obviously lower than that in surrounding areas. The epicentral locations of strong earthquakes in Yunnan region are mainly distributed in transitional zones between low and high phase velocities.

New theoretical analysis method for the phase center in the Fresnel region of complex structure antennas

A finite domain time difference （FDTD） and second-derivative combined method is proposed for the evaluation of phase center in the Fresnel region of complex structure millimeter antennas. This method adopts FDTD＇s near to far field transformation to obtain the fields in Fresnel region and then applies the second-derivative method to calculate the phase center. The adoption of FDTD efficiently overcomes the difficulties arising from the existing calculation methods＇ requirements for the radiation analytical formula of some complex antennas, which makes the existing second-derivative method more applicable in engineering. Also, FDTD increases the precision owing to the superposition field calculation from its extrapolation. The correctness of this proposed method is certified with typical examples and the phase center in the Fresnel region of a microwave radiometry calibration corrugate horn antenna is evaluated with the key features.

The Solid-liquid Transformation of Low-grade Solid Potash Deposit in Dalangtan Basin and the Simplification of the Liquid Phase System

We studied the solid-liquid transformation of low-grade solid potash deposit in Dalangtan Basin and simplified the liquid phase system.We did experiments to optimize conditions of the solid-liquid transformation.The Suitable

Medical Image Registration Based on Phase Congruency and Regional Mutual Information

In this paper, a new approach of muhi-modality image registration is represented with not only image intensity, but also features describing image structure. There are two novelties in the proposed method. Firstly, instead of standard mutual information （ MI ） based on joint intensity histogram, regional mutual information （ RMI ） is employed, which allows neighborhood information to be taken into account. Secondly, a new feature images obtained by means of phase congruency are invariants to brightness or contrast changes. By incorporating these features and intensity into RMI, we can combine the aspects of both structural and neighborhood information together, which offers a more robust and a high level of registration accuracy.

SOLID-LIQUID PHASE TRANSFER CATALYTIC SYN THESIS Ⅸ: THE SYNTHESIS OF α-AMINO ACIDS VIA ALICYLATION OF ALDIMINE UNDER MICROWAVE IRRADIATION,

The rapid alkylation of methyl N-benzylidene glycinate with halides under microwave irradiation using solid-liquid phase transfer condition without solvent has been achieved wilhin only one minute. After hydrolysis of alkylated products the corresponding α-amino acids were obtained in overall yield 43.6～62.5%.

Studies on Solid-Liquid Phase Transfer Equilibrium of Onium Salts(Ⅱ)

The present paper contains the effects of the ammonium ion, counter ion, solvent and anion being transferred on the solid-liquid phase transfer equilibrium constant of quaternary ammonium salts. The most striking difference between solid-liquid and liquid-liquid phase transfer equilibriums is that the length of alkyl chain shows a large effect on the latter but little on the former This means that the chain length affects only the hydrophobicity, rather than the lipophilicity.Keywords Quaternary ammonium salt, Phase transfer catalysis, Equilibrium constant, Hydrophobicity, Lipophilicity

SOLID-LIQUID PHASE TRANSFER AND COBALT OR PALLADIUM COMPLEX CATALYZED SYNTHESIS OF ANHYDRIDES FROM ACYL CHLORIDES

Acyl chloride can efficiently be converted into anhydride under solid liquid phase transfer catalysis by using bis(triphenylphosphine)cobalt dichloride or bis(triphenylphospine)palladium dichloride as the catalyst.

THE APPLICATON OF ULTRASOUND TO THE DI-ALKYLATION AND CYCLO-DI-ALKYLATION OF ETHYL CYANOACETATE UNDER SOLID-LIQUID PHASE TRANSFER CONDITIONS

Comparative experiments show that ultrasonic irradiation reduces the reaction times and improves the yields in the di-alkylation and cyclo-di-alkylation of ethyl cyanoacetate under solid-liquid phase transfer conditions.

REACTION OF ETHYL N-CYANOMETHYLBENZEHECARBOXIMIDATE WITH ALIPHATIC ALDEHYDES UNDER THE SOLID-LIQUID PHASE TRANSFER CATALYSIS

Ethyl N-cyanomethytbenzenecarboximidate reacted with aliphatic aldehydes under the solid-liquid PTC condition to gire a-ethoxyphenylmethylene- aminoacrylonitrile derivatives and oxazoline derivatives.It is a convenient and new method for synthesis of β,β'-dihyroxy-a-amino acids by hydrolysis of the oxazoline derivatives.

Heptad Phase Vortex Array in Extremely Deep Fresnel Diffraction Region Generated by Asymmetrical Metal Subwavelength Holes Film

We report a heptad vortex array structure in the wave fields in an extremely deep Fresnel diffraction region by asymmetrical subwavelength holes in a metal film illuminated with linearly polarized light. A Mach Zehnder interferometer with a microscopic objective is used to record the wave fields at different distance＆ and the phase maps are extracted by Fourier transform of the interference intensities. We study the evolutions of the heptad vortex array with distance from the sample to the object plane. To explain the formations and the evolutions of the vortex array, we calculate the diffracted wave fields with Kirchhoff＇s diffraction theory. The calculations are basically consistent with the experimental results, and the properties of the heptad vortex array structure are reasonably explained.

Projected Regional 1.50℃and 2.00℃Warming Threshold-crossing Time Worldwide Using the CMIP6 Models

The Paris Agreement aims to limit global warming to well below 2.00℃and pursue efforts to limit the temperature increase to 1.50℃.However,the response of climate change to unbalanced global warming is affected by spatial and temporal sensitivities.To better understand the regional warming response to global warming at 1.50℃and 2.00℃,we detected the 1.50℃and 2.00℃warming threshold-crossing time(WTT)above pre-industrial levels globally using the Coupled Model Intercomparison Project phase 6(CMIP6)models.Our findings indicate that the 1.50℃or 2.00℃WTT differs substantially worldwide.The warming rate of land would be approximately 1.35–1.46 times that of the ocean between 60°N–60°S in 2015–2100.Consequently,the land would experience a 1.50℃(2.00℃)warming at least 10–20 yr earlier than the time when the global mean near-surface air temperature reaches 1.50℃(2.00℃)WTT.Meanwhile,the Southern Ocean between 0°and 60°S considerably slows down the global 1.50℃and 2.00℃WTT.In 2040–2060,over 98.70%(77.50%),99.70%(89.30%),99.80%(93.40%),and 100.00%(98.00%)of the land will have warmed by over 1.50℃(2.00℃)under SSP(Shared Socioeconomic Pathway)1–2.6,SSP2-4.5,SSP3-7.0,and SSP5-8.5,respectively.We conclude that regional 1.50℃(2.00℃)WTT should be fully considered,especially in vulnerable high-latitude and high-altitude regions.

数字经济、绿色技术创新与能源效率提升——基于城市面板数据的实证分析

提高能源效率是我国经济绿色转型和实现双碳目标的必然要求,当下数字经济已成为能源效率提升的新动能。本文基于数字经济的“四化”框架,在理论分析的基础上,运用2011~2020年我国284个地级市的面板数据,实证检验了数字经济影响能源效率提升的机制、特征和路径。结果表明:(1)数字经济及各维度对能源效率提升的总体效应为正,其中产业数字化促进作用最强,且数字经济对能源效率的提升具有区域异质性;(2)数字经济对能源效率的提升存在双门槛,呈现中间波动但总体促进的“N”型特征;(3)数字经济可通过促进绿色技术创新进而提升能源效率,且绿色技术创新水平的提高有助于城市跨越数字经济的第二个门槛,实现数字经济发展与能源效率提升的共赢。

影响山西台网地震定位因素的定量分析

基于山西地震台网现有的台站布局,利用数值模拟方法定量分析地壳速度模型、台网布局及震相拾取精度等因素对震源位置测定的影响,结果显示,3种因素对准确测定震源位置的影响不同。地壳速度模型中上地壳速度对震中位置的影响最大,而震中位置对莫霍面速度变化的反映更为灵敏。单独改变地壳速度模型引起的震中位置偏差通常不超过5 km,震源深度对地壳速度模型的变化十分敏感,尤其是莫霍面深度,最大偏差可能超过20 km。在不考虑其他因素的条件下,P波拾取精度在4 s以内测定的震中位置和震源深度最大偏差不超过2 km和5 km。当地壳速度模型适宜且震相拾取精度较高时,最大空隙角在0°~180°的台站布局对震源位置的约束较好,震中偏差基本小于1 km,震源深度偏差略大(约为2 km)。

寒区相变蓄热墙体多因素热特性研究

在墙体中应用相变材料可以显著改善墙体的保温蓄热能力,但相变材料厚度和墙体构造的选择尚需科学论证。基于寒区气象特点,选择适用于寒区建筑外墙的相变储能材料,从墙体的传热特性角度出发,通过建立不同相变材料层厚度和多种构造的相变墙体模型,研究多种情况相变墙体的热特性。结果表明,相变墙体在冬季的保温蓄热能力受相变材料层位置和厚度影响,夏季效果主要受相变材料厚度影响;相变材料厚度为40 mm的中间型相变墙体和相变材料厚度为60 mm的内侧型相变墙体比较适合寒区建筑应用。研究所得结论可为寒区相变墙体的结构设计优化提供参考。

汽车用IF钢连铸坯第Ⅲ脆性区及其形成机理分析

探明连铸坯第Ⅲ脆性区及其形成机理对避免铸坯裂纹的产生、有效调控铸坯性能具有重要指导作用。采用Gleeble热/力模拟试验机对汽车用IF钢铸坯的高温力学性能进行了试验研究,结合热膨胀测试及组织分析手段,探究了IF钢铸坯第Ⅲ脆性区的形成机理。结果表明:IF钢的高温热塑性较优异,第Ⅲ脆性区温度范围为850~950℃,二冷低延性区为875~925℃,1250℃以上抗拉强度和屈服强度分别低于30 MPa和20 MPa,从变形和受力两个角度综合考虑,矫直区温度应控制在950~1250℃。第二相含量在950℃左右达到最高,大量微米级的TiN和少量TiN与MnS复合第二相会导致热塑性下降。950℃以下大量微米级第二相、A_(e3)温度附近形变诱导铁素体以及A_(ff)~A_(r3)温度范围内奥氏体分解的共同作用是导致IF钢连铸坯第Ⅲ脆性区形成的根本原因,不同冷速下IF钢铸坯二冷低延性区的温度范围与T_(α)^(40%)(C_(R))~A_(e3)基本一致。

T型三电平逆变器非对称矢量脉冲宽度调制相电流重构策略

针对T型三电平逆变器中点电流单传感器传统相电流重构方法存在不可观测区的问题,分析中点电流采样过程中不可观测区的存在机理,提出非对称矢量脉冲宽度调制相电流重构策略。通过移位PWM波延长基本电压矢量的作用时间,消除不可观测区,实现相电流重构。实验结果表明,所提方法的电流重构误差低于2.2%,输出相电流畸变率低于3.48%。

Numerical simulation for solid- liquid phase change of metal sodium in combined wick

Based on the finite volume method and the enthalpy-porous model the solid-liquid phase change of sodium in the combined wick is numerically studied.The one-temperature model is used since the thermal conductivity of sodium is close to that of the combined wick materials.The non-Darcy law and natural convection in the melting process are taken into account.The results show that a thin metal fiber felt in the combined wick can result in a faster melting rate of the sodium and a shorter time for the molten sodium to reach the maximum velocity which can shorten the time for the high-temperature heat pipe startup.A thick metal fiber felt in the combined wick can result in a uniform temperature distribution in the vertical heating wall and a small wall temperature difference which can reduce the possibility of an overheat spot.

SCM435冷镦钢的球化退火工艺

为获得球状珠光体以改善冷镦性能,对SCM435冷镦钢进行了亚温退火和亚温退火加两相区温度退火,前者为700℃保温4 h炉冷至580℃空冷,后者为700℃保温3.5 h,再升温至745℃保温0.5 h炉冷至580℃空冷。检测了退火后钢的显微组织、力学性能和冷镦性能。结果表明:经两种工艺球化退火后,SCM435钢的显微组织均为铁素体和球状珠光体,与热轧态相比断后伸长率和断面收缩率均提高、抗拉强度降低;经两种工艺球化退火的SCM435钢均能进行大变形率冷镦而不开裂。