BaM、BaCoTiM、BaZnTiM的柠檬酸溶胶-凝胶合成及其微波介电性能、磁性能研究

采用柠檬酸sol—gel工艺，以柠檬酸铁、碳酸钡、硝酸钴、硝酸锌、钛酸四丁酯以及柠檬酸等为原料合成了BaFe12O19，、Ba(CoTi)xFe12—2xO19、Ba(ZnTi)sFe12—2xO19(x＝0．2、0．6、1．0)铁氧体。采用XRD、SEM对其相成分和显微结构进行研究。并对其复介电常数、复磁导率在1MHz-6GHz下的变化规律进行了研究。结果表明3种铁氧体的复介电常数随微波测试频率的增加而变小，其磁导率虚部随测试频率的变化曲线上显示出非常明显的由畴壁共振引起的共振峰，该共振峰随铁氧体粉末热处理温度的升高移向低频。     

BaFe12O19／Al2O3—SiO2—K2O微晶玻璃陶瓷的柠檬酸Sol—Gel合成及其微波性能的研究

采用柠檬酸sol-gel工艺合成了BaFe12O19/Al2O3-SiO2-K2O微晶玻璃陶瓷，并对其介电常数及其磁导率在1MHz～6GHz下的变化规律进行了研究。结果表明，BaFe12O19/Al2O3-SiO2-K2O微晶玻璃陶瓷的合成与体系中Fe/Ba、烧结温度密切相关；其介电常数、磁导率基本都随测试频率的增加而下降；介电损耗值最大可达到0.30，磁损耗值较小。     

BaFe12O19/SiO2微晶玻璃陶瓷的柠檬酸盐Sol-Gel合成及其微波性能的研究

采用柠檬酸sol-gel工艺合成了BaFe12O19/SiO2微晶玻璃陶瓷,并对其介电常数及其磁导率在100MHz-6GHz下的变化规律进行了研究。结果表明,BaFe12O19/SiO2微晶玻璃陶瓷的合成与体系中Fe/Ba,烧结温度密切相关;其介电常数、磁导率基本都随测试频率的增加而下降,介电损耗值最大达到0．40,磁损耗值较小。     

BaFe12O19/A12O3-SiO2-K2O微晶玻璃陶瓷的柠檬酸SOl-Gel合成及其微波性能的研究

采用柠檬酸sol-gel工艺合成了BaFe12O19/A12O3-SiO2-K2O微晶玻璃陶瓷,并对其介电常数及其磁导率在1MH2～6GHz下的变化规律进行了研究.结果表明,BaFe12O19/Al2O3-SiO2-K2O微晶玻璃陶瓷的合成与体系中Fe/Ba、烧结温度密切相关;其介电常数、磁导率基本都随测试频率的增加而下降;介电损耗值最大可达到0.30磁损耗值较小.     

BaFe12O19-BaTiO3/SiO2-B2O3微晶玻璃陶瓷的sol-gel合成及微波性能

采用柠檬酸sol-gel工艺合成了BaFe12O19-BaTiO3／SiO2-B2O3微晶玻璃陶瓷，对其介电常数及其磁导率在1MHz－6HGz下的变化规律进行了研究。结果表明其复介电常数和复磁导率值基本随测试频率的增加而下降。     

BaFe12O19/SiO2-B2O3微晶玻璃陶瓷的制备和微波性能

采用柠檬酸sol-gel工艺合成了BaFe12O19/SiO2-B2O3微晶玻璃陶瓷，研究了SiO2-B2O3玻璃的含量，Ba/Fe原子比和热处理温度对体系析出晶相的影响，以及介电常数和磁异率在1MHz-6GHz频率范围的变化规律，结果表明，休系中SiO2-B2O3玻璃的含量和Ba/Fe比越高，BaF312O19相的析出越困难，前驱体合适的热处理温度为1000℃，介电常数和磁导率基本上随测试频率的增而加下降；介电损耗的最大值为0．43，磁损耗较小。     

六角晶系钡铁氧体与锶铁氧体吸波性能的比较

采用柠檬酸盐溶胶一凝胶法制备了六角晶系钡铁氧体BaFe12O19与锶铁氧体SrFe12O19.采用XRD、AFM、TEM研究了产物的粒形、粒径与矿物组成.结果表明,铁氧体的平均粒径为50nm.采用网络分析仪分别测试了0.1～6GHz内铁氧体的介电常数、磁导率与12～18GHz内吸波涂层的微波损耗.结果表明,钡、锶铁氧体的介电常数虚部形态与损耗角正切形态基本相同,但钡铁氧体在较宽的频率范围内具有较多的损耗角正切峰值,钡铁氧体的吸波性能优于锶铁氧体.     

碳化硅表面钡铁氧体薄膜制备与吸波性能

采用柠檬酸盐溶胶-凝胶法在碳化硅表面形成钡铁氧体薄膜.XRD表明生成的铁氧体为六角磁铅型晶体BaFe12O19.测定了材料在0.1～6.0 GHz内的介电常数与磁导率.与单纯钡铁氧体比较,碳化硅表面沉积钡铁氧体薄层后复合相吸波频段宽化,吸波能力增强.     

Ba2ZnZCo2-ZFe12O22-SiO_2微晶玻璃陶瓷的sol-gel合成及性能研究

采用柠檬酸so1-gel工艺合成了Ba2ZnzC02-zFel2O22-SiO2微晶玻璃陶瓷；采用XRD、SEM对其相成分、显微结构进行了分析，结果表明，1200℃／5h得到的BBa2ZnzC02-zFel2O22-SiO2微晶玻璃陶瓷的平均晶粒尺寸在0．3μm左右；采用HP8753E网络分析仪测定了微晶玻璃陶瓷在100MHz～6GHz范围内的介电常数及其磁导率，其复介电常数值、磁导率实部都随测试频率的增加而减小，其磁导率虚部～f曲线上显示出明显的自然共振峰。     

X、U铁氧体的溶胶-凝胶合成及微波性能研究

以檬檬酸铁、碳酸钡、硝酸钴、硝酸锌以及柠檬酸等为原料，采用sol-gel工艺合成了Ba2Zn2Fe28O46(Zn2-X)、Ba2Co2Fe28O46(Co2-X）、Ba4Zn2Fe36O60(Zn2-U)、Ba4Co2Fe36O60(Co2-U)铁氧体。采用XRD、SEM对其相成分和显微结构进行研究。并对其复介电常数、复磁导率在100MHz-6.0GHz下的变化规律进行了对比。结果表明，铁氧体试样的磁导率虚部随测试频率的变化曲线上显示出非常明显的由自然共振引起的共振峰。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...