掺Er~(3+)重金属氧氟锗酸盐玻璃光谱性质研究

研究了重金属氧氟锗酸盐玻璃中Er3+离子的吸收光谱、有效吸收和发射线宽、荧光光谱、荧光半高宽、荧光寿命、带宽特性和增益性能.应用Judd-Ofelt理论计算了Er3+离子的强度参数Ωt(t=2,4,6),应用McCumber计算了能级4I13/2→4I15/2跃迁的吸收和受激发射截面.结果显示,随PbF2含量增加,Er3+离子的强度参数Ω6,吸收线宽、发射线宽、荧光半高宽、荧光寿命、带宽特性和增益性能都增加.表明掺Er3+重金属氧氟锗酸盐玻璃可作为宽带光纤放大器潜在的基质材料.     

掺铒氧氟碲酸盐玻璃的上转换发光研究

研究了掺铒氧氟碲酸盐玻璃的吸收光谱和上转换发光光谱，分析了Er^3 离子在氧氟碲酸盐玻璃中的上转换发光机理．结果表明：通过975nm的激光二极管(LD)激发，在室温下同时观察到强烈的绿光(524和545nm)和红光(655nm)，分别是由于Er^3 离子^2H11／2→I15／2，^4S3／2→I15／2，和^4F9/2→I15／2跃迁．随PbF2含量增加，绿光的发光强度增加趋势较小，而红光的发光强度增加趋势大于绿光．上转换发光机理主要涉及能量转移和激发态吸收，强烈的绿光和红光激发都是由于双光子吸收过程．     

不同铒离子掺杂浓度下碲酸盐玻璃荧光特性研究

测试了掺铒碲酸盐玻璃的荧光特性，研究了。^4I13／2能级上Er^3＋离子的荧光谱、荧光强度和荧光寿命．研究显示，掺铒碲酸盐玻璃中存在着强烈的荧光俘获效应和浓度猝灭效应．荧光俘获效应使得荧光谱中的各谱线成分相对强度随着Er^3＋离子掺杂浓度的增加发生改变，从而导致荧光谱主峰的变迁和荧光谱的展宽．Er^3＋离子间的协作上转换引起的能量转移，使得荧光强度在较高掺杂浓度下发生猝灭．同时，荧光俘获效应和浓度猝灭效应的相互作用，导致荧光寿命随着Er^3＋离子掺杂浓度的增加呈现出先增大后减小的变化趋势．     

1.55μm光纤放大器用掺Er3+碲酸盐玻璃光谱性能研究

制备了TeO2-BaO(Li2O,Na2O)-La2O3掺铒碲酸盐玻璃系统,测量玻璃的密度、折射率和DSC曲线,以及玻璃的吸收光谱和荧光光谱.由测得的密度和折射率等参数,应用Judd-Ofelt理论和McCumber理论,计算出碲酸盐玻璃的各光学性能参数与受激发射截面.且从测得热稳定性能较好的TBLE3荧光发射谱图中得到该碲酸盐玻璃荧光半高宽(FWHM)为～60nm,σepeak×FHWM值高达～600,明显大于掺铒硅酸盐玻璃和磷酸盐玻璃,表明该种碲酸盐玻璃是光纤发大器用的理想基质材料.     

激光器用Yb3+掺杂钨锌镧碲酸盐玻璃的热学、光谱和激光性质

设计组成为70TeO2—(20—x)ZnO—xWO3—5La2O3—2．5K2O—2．5Na2O—1Yb2O3(x=0，5，10，15和20mol％)的碲酸盐激光玻璃，测试了物理性质、吸收光谱、荧光光谱和荧光寿命，计算了Yb^3 离子的吸收截面、受激发射截面、荧光有效线宽等参数．结果表明，随着WO3含量的增加，玻璃的热稳定性下降；当x=15mol％时，具有体系中最好的光谱性质：高的受激发射截面(1．32pm^2)、长的荧光寿命(0．93ms)和宽的荧光有效线宽(74．5nm)，通过激光性能评价，最小泵浦强度为0．92kW／cm^2，表明掺Yb^3 该组分碲酸盐玻璃是实现高能短脉冲可调谐激光器的理想增益介质。     

掺铒碲酸盐玻璃光谱性质的J-O计算

研究了掺Er3+碲酸盐玻璃的吸收和荧光光谱性质;应用Judd-Ofelt理论计算了碲酸盐玻璃中Er3+离子的强度参数Ω(Ω2=4.79 × 10-20cm2,Ω4=1.52×10-20cm2,Ω6=0.66×10-20cm2),计算了离子的自发跃迁几率,荧光分支比;应用McCumber理论计算了Er3+的受激发射截面(σe=10.40 × 10-21cm2)、Er3+离子4I13/2→4I15/2发射谱的荧光半高宽(FWHM=65.5nm)及各能级的荧光寿命(4I13/2能级τrad=3.99ms);比较了不同基质玻璃中Er3+离子的光谱特性,结果表明掺铒碲酸盐玻璃更适合于掺Er3+光纤放大器实现宽带和高增益放大.     

掺Er3+硅酸盐玻璃上转换发光特性研究

研究了掺Er^3＋硅酸盐玻璃的吸收光谱和上转换光谱，应用Judd-Ofelt理论计算了Er^3＋强度参数Ωλ（λ=2、4、6）、跃迁振子强度、自发辐射几率、荧光分支比．上转换光谱分析表明：在522、545、658nm处有较强的绿光和红光，分别对应于^2H11／2→^4I15／2、^4S3／2→^4I15／2、^4F9／2→^4I15／2的跃迁，发光曲线拟合斜率分别为1．67，1．94，1．76；上转换发光机制主要是激发态吸收和能量转换，且均为双光子吸收过程．     

碱金属和碱土金属对掺Tm3+碲酸盐玻璃光谱性质的影响

研究了碱金属和碱土金属离子修饰的掺铥碲酸盐玻璃的光谱性质,讨论了碱金属和碱土金属对掺铥碲酸盐玻璃J-O强度参数、1.46μm荧光发射强度、荧光半高宽、受激发射截面等光谱性质的影响,并与一些传统氧化物玻璃进行了比较.研究表明碱金属Li 和碱土金属Ba2 掺碲酸盐玻璃更适宜用作掺铥光放大器基质.含Li 的碲酸盐玻璃展现出7.90×10-21cm2的高发射截面;含Ba2 碲酸盐玻璃具有7.55×10-21cm2的高发射截面、103nm的荧光半高宽.     

Er3+掺杂的MFT玻璃材料2H11/2、4S3/2→4I15/2荧光性质

计算了Er^3 掺杂的氟氧化物玻璃材料MFT的J－O参数,进而获得了一些能级间跃迁的跃迁几率、分支比、及寿命等数据,测量了室温下Er^3 的较强的两个绿色发射^2H11／2、^4S3／2→^4I15／2及红色发射^4F9／2→^4I15／2的激发光谱,观测了^2H11／2、^4S2／2→^4I15/2跃迁荧光强度随着温度的变化,测量了室温下这两筹这衰减曲线,计算了这两个能级的无辐射跃迁几率及量子效率。     

Er3+在TeO2-WO3-La2O3玻璃中的光谱性质和热稳定性研究

制备了掺铒的玻璃样品TeO2-WO3-La2O3．测试了样品的吸收光谱、荧光光谱以及玻璃的热稳定性．应用Juddo-Ofelt理论计算了玻璃的三个强度参数Ωt（t=2、4、6），电偶极跃迁谱线强度以及磁偶极跃迁谱线强度，分析了强度参数Ω2和玻璃成分变化的关系．应用McCumber理论计算了Er^3＋在1．5μm处的受激发射截面．TeO2-WO3-La2O3玻璃在La2O3的含量〉5mol％时，未发现析晶开始温度（Tx），说明这种玻璃材料适合于光纤的拉制．研究结果表明TeO2-WO3-La2O3是制备宽带光纤放大器的理想基质材料．     

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.……     

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...     

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.     

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 ...