Consistency retention method for CNC machine tool digital twin model

Computer Numerical Control Machine Tool (CNCMT) Digital Twin (DT) model is a carrier for complex, time-varying, coupled data of CNCMT, which can theoretically provide a time-varying high-fidelity model. However, there are still many difficulties in its implementation process. And the key issue is how to realize the updated DT model with performance attenuation and validate it. In order to solve this problem, a model consistency retention method for CNCMT DT model is studied and proposed in this paper. Firstly, the framework of consistency retention method for DT model is designed including both digital space and physical space. The principles of data management and performance attenuation update in digital space are elaborated. Then, the implementation method for consistency retention of CNCMT DT model is studied in terms of performance attenuation update workflow for wear and other damage separately. Finally, a case study for the establishment and application of high-fidelity test bench DT model that focusing on rolling guide-rail is carried out to show the implementation flow of the proposed method and verify its operability and effectiveness.     

Microwave surface resistance of epitaxial YBa2Cu3O7 thin films at 18.7 GHz measured by a dielectric resonator technique

We used a dielectric resonator technique for highly sensitive measurements of the temperature dependence of the microwave surface resistanceR _s of 1×1 cm² superconducting films at 18.7 GHz. It consists of a sapphire disc positioned on the film under investigation within a copper cavity which is acting as a radiation shield. In the TE₀₁ oscillation mode the highly reproducible quality factor of about 10⁵ results in a sensitivity of ±50 forR _s measurements. The temperature dependence ofR _s can be measured up to values as high as 1 . We have investigated several YBa₂Cu₃O₇ thin films prepared by high oxygen pressure d.c. sputtering on LaAlO₃ and NdGaO₃. Our best films exhibit a pronounced nonlinear behavior of the d.c. resistivity(T) with(300K)/(100K) values of about 3.7. Those films show, besides the initial fall-off just belowT _c , a further strong decrease ofR _s at low temperatures. This was observed both at 18.7 GHz and 87 GHz, as measured by a conventional cavity end plate replacement technique. ForTT_c/2 these films exhibit an exp (–T _c/T) dependence ofR _s with-values around 0.4. These observations may be explained by a superconducting energy gap with 2/kT _c0.8 for charge carriers localized in the CuO chains for YBa₂Cu₃O₇.     

Global insight into microwave stoneware firing: Macro and microstructural changes

Industrial competition and environmental concerns lead to the exploration of alternative and energy-efficient technologies for ceramic materials processing. The main objective of this work was to present microwave heating as a viable option for stoneware processing. Stoneware functional properties are presented and discussed, with emphasis on impact strength, water absorption, porosity, and color. Microstructure analyses show that microwave- and gas-fired samples have higher densifications than electrically fired samples. A relevant finding for processing conditions is that microwave firing requires temperatures approximately 100°C lower than those required by conventional firing. Microwave-fired samples’ rupture energies are approximately twice (0.57 ± 0.06 (J)) those of the reference samples (0.26 ± 0.03 (J)), and their water absorptions are approximately one-half (1.5% at 1170°C and 0.8% at 1190°C) of those of the reference samples (2.0%), whereas the water absorption of electrically fired samples at 1180°C has been estimated to be 7.5%. Color analysis also evidences a shift to lower microwave firing temperatures, what is attributed to the enhanced transformations promoted by microwave heating when comparing with the transformations promoted by conventional (gas or electric) heating.     

氟硅酸钾滴定法测定粗制氟化钠中二氧化硅

采用硝酸-氢氟酸混合酸为消解溶剂,通过微波消解技术对粗制氟化钠进行快速消解,并用氟硅酸钾滴定法测定其二氧化硅含量。选择饱和氯化钾溶液替代固体氯化钾作为沉淀剂,考察了消解酸体系、饱和氯化钾溶液用量、沉淀温度、沉淀放置时间、共存元素干扰及指示剂选择等条件对测定结果的影响并进行优化。确定了最优测试条件：以8 mL硝酸+2 mL氢氟酸为消解溶剂,以8 mL饱和氯化钾溶液为沉淀剂,控制沉淀温度为20~25 ℃、沉淀放置时间为15 min,选择50 g/L氯化钾-50%乙醇溶液洗涤沉淀,采用溴麝香草酚蓝-酚红指示剂。该方法应用于回收粗制氟化钠中二氧化硅含量的测定可大幅度缩短分解试样的时间,有效降低检测成本,回收率为99.15%~100.63%,相对标准偏差（RSD,n=8）小于1%,与传统高温碱熔法测定结果相符,方法的准确度和精密度较好。     

Preparation of alumina-doped yttria-stabilized zirconia nanopowders by microwave-assisted peroxyl-complex coprecipitation

Alumina-doped yttria-stabilized zirconia （ADYSZ） nanopowders were prepared by microwave-assisted peroxyl-complex coprecipitation （MAPCC） using ZrOCl2-8H2O, Y2O3 and AICly6H2O as starting materials, NH2-H2O as precipitant and H2O2 as complexant. The effects of adding H2O2 and microwave drying on the preparation and properties of ADYSZ were investigated. The precursors and nanopowders were studied by EDX, XRD, SEM and TEM techniques. The results show that the uniformity of component distribution within ADYSZ nanopowders is improved by adding appropriate dosage of H2O2. Complexing reaction between H2O2 and Zr^4＋ ion restrains the hydrolyzation and precipitation of Zr^4＋ ion. With the addition of H2O2, Al^3＋, y^3＋ and Zr^4＋ ions can be precipitated synchronously in a relatively narrow range of pH value. H2O2 also improves the filterability of the wet precipitate. The highly hydrophilic precipitates can be quickly and effectively separated from aqueous solution. During microwave drying process, the moisture of wet precursors is selectively heated. Quick expansion of steam vapor within the wet colloidal particles causes the aggregations burst into numerous tiny lumps. Compared with oven drying, microwave drying can not only shorten drying time but also reduce aggregation intensity of the resultant ADYSZ nanopowders.     

磁性纤维随机混合媒质等效电磁参数的计算

为计及强散射偶极子间的相互作用,引入参量εh和μh,利用广义多重散射理论及MATLAB计算机软件对在2 GHz～18 GHz频率下的体积占空比为8%的铁纤维随机混合媒质等效磁导率的实验值进行曲线的拟合,导出了耦合系数εh和μh,并在此基础上,对体积占空比分别为30%和20%的铁纤维随机混合媒质等效磁导率进行了计算,计算结果与实验吻合良好.     

Ce^3＋,Sb^3＋共激活的亚超细磷光体的微波快速合成和发光特性

首次采用微波辐射法快速合成了亚超细CaS:C^3 ,Sb^3 高效绿光磷光体，发现Ce^3 与Sb^3 离子之间存在着能量传,租是属于多极子相互作用的共振传递，因而Ce^3 对CaS:Sb^3 的发光有明显的敏化和增强。微波场作用下合成的双掺磷光体的激发峰与发射峰值分别恒定在259nm 和523nm处，并没有像传统高温固相合成法那样，随掺杂离子浓度的增大而发生红移现象。SEM照片显示，采用含不同一价阳离子（Na^ ,K^ ,NH4^ )无机盐作助熔剂制得的亚超细CaS:Ce^3 ,Sb^3 磷光体平均粒径为300nm-500nm，但其晶体形貌分别为立方形、球形和团聚状的雪花形，其中球形磷光体荧光最强。     

Synthesis of LaF3 superfine powder by microwave heating method

LaF3 superfine powder was synthesized from La(CH3COO)3 and NH4 F by microwave heating method,using ethanol or pure water as dispersants respectively. The results of XRD and SEM indicate that the superfine powder has high purity, regular particle shape and narrow distribution of granularity. The granularity of the best sample is in the range of 100 -200 nm. The influence of different dispersants on the crystal degree and microstructure was discussed. After the superfine powder was formed into a slice at pressure of 25 - 60 MPa, its electrochemical impedance spectroscopy was tested by electrochemical impedance spectroscopy (EIS) measurement. The result shows that the grain refining of LaF3 powder increases its ionic conductivity. Compared with traditional preparation methods of LaF3 powder, the advantages of microwave heating method were summarized.     

利用微波介电加热和微波干燥水解法制备TiO2微粒

利用微波介电加热和微波干燥条件下TiCl4直接水解的方法制备出平均尺寸为40m，粒径分布窄，均为球形且形态均一，团聚较少，金红石型的TiO2纳米粒子，其内部品粒平均大小为17nm。而传统加热和干燥条件下形成的纳米微粒平均为60nm，粒经大小不均一，形态较不规则，团聚严重。微波加热和干燥方法具有清洁、快速均匀高效、环境友好的优点，推广前景良好。TiCl4水解法经济便利，适于工业化生产。