二维光子晶格的带隙位置以及影响带隙宽度的因素研究

利用四孔振幅掩模的傅里叶变换法,在LiNbO3∶Fe晶体中制作了二维光子晶格,利用功率计测量其透射效率,找到满足Bragg衍射条件的带隙并测量出了二维正方晶格斜45°角方向上以及水平方向上的相对带隙宽度。实验结果表明,在照射相同条件下二维正方格子斜45°方向上的相对禁带宽度比水平方向上的相对禁带宽度宽。     

无铅镉橡胶箍圈的研制

介绍了无铅镉橡胶箍圈的研制。通过对EN71PART38大重金属标准的相关要求的剖析，以及胶料物理性能和移行性试验要求，阐述了同时满足3项技术要求的配方设计特点、工艺过程控制、作业环境的保障措施，可获得铅含量符合EPA3050B、镉含量符合EN1122重金属标准、物理性能达标且无色泽移行的橡胶箍圈。     

Band energy structreu and optical spectra

The article deals with the simulation of band energy structure of rhombohedral and monoclinic modifications of Cs₂Cdl₄ crystals.     

Band engineering of oxygen doped single-walled carbon nanotubes

We have studied the electronic characteristics of chemically modified single-walled carbon nanotubes by oxygen doping using first-principles density-functional calculations. The oxygen doping, a controlled [2 + 1] cycloaddition scheme, is shown to modify the π-conjugation and impact on the near-infrared band gaps. The implications of tailoring the electronic structure of oxygen doped carbon nanomaterials for future device applications are discussed.     

Separation of Nitrogen Isotopes by Displacement Band Chromatography

Abstract

A study of the separation of ¹⁴N and ¹⁵N isotopes via displacement band chronatography was conducted using sulfonated styrene-divinylbenzene resins. Starting with a feed solution of 0.5 N NH₄OH (containing 51% ¹⁵N), a band was developed that generated a concentration profile ranging from 11 to 85 % ¹⁵N. The separative power and HETP (height equivalent to a theoretical plate) were found to be dependent on the resin characteristics (size, crosslinkage) and operating parameters (superficial velocity, concentration). The use of a 7/10-microneter-size, high performance resin increased the separative power by a factor of 17 and decreased the HETP by a factor of 10, when compared to a 100/200 mesh Dowex 50W-X12 resin under similar process conditions. The HETP could further be reduced by lowering the superficial velocity and/or eluant concentration.     

填充聚四氟乙烯导轨软带的生产技术

着重介绍以聚四氟乙烯为主要原料,填充适量的青铜粉制成机床导轨软带的生产技术。用此技术生产的填充聚四氟乙烯导轨软带表面平整,色泽均匀,无明显划痕及其他缺陷,软带边缘平直,1米长度的弓弦高不大于 3米。其与铸铁粘接后剪切强度 >10N/mm2 ,与铸铁 180°剥离强度 >2 4N/cm。     

Main Wear Mechanisms of SEN Slag Band Materials

This paper summarizes experimental approaches and simulation results in order to establish a general proposition regarding SEN wear mechanisms.Marangoni convection is considered to be a major contribution to continuous SEN wear,usually causing characteristic corrosion grooves.It is governed by the interface tension gradient in the vicinity of the three phase boundary slag/refractory/steel.This interface tension gradient is caused by a lower activity of the oxygen dissolved in the steel close to the refractory/steel interface.This is due to the reducing action of the solid carbon,which is a component of the refractory.By a simulation model using the Effective Equilibrium Reaction Zone technique a calculation of the interface tension differenceΔσwas performed.While for an LC steel and the related slag a valueΔσ=150mN/m was received,this quantity is negligible in the case of a TRIP steel.Accordingly,also the wear is much less for the TRIP steel.Marangoni convection is decisive for the mass transfer at the refractory/slag interface.Here dissolution of zirconia,but also oxidation of carbon takes place.For the latter one,the above mentioned simulation showed that reduction of silica in the mold slag takes place at the three phase boundary slag/refractory/steel by solid carbon,as the activity of silicon is reduced by dissolution in the liquid steel.This is the main source of oxygen for carbon oxidation at the three phase boundary.Therefore the three phase boundary is the focus of SEN wear:It unites intense bath movement due to Marangoni convection,oxidation of carbon by SiO_2reduction and zirconia erosion and dissolution into the melt.Within the refractory itself,a thin layer of several millimetres shows reactions with slag components.This causes especially destabilisation of stabilised zirconia and prepares later erosive wear.Steel does not penetrate into the SEN microstructure,carbon dissolution is only possible at the steel/refractory interface.The results quoted here enable justified expectations about the SEN wear in dependence on the steel/slag grade.Further simulation offers the possibility to quantify the effect of parameter variations on SEN wear.     

Band gap opening in methane intercalated graphene

Recent experimental work has demonstrated production of quasi-free-standing graphene by methane intercalation. The intercalation weakens the coupling of adjacent graphene layers and yields Dirac fermion behaviour of monolayer graphene. We have investigated the electronic characteristics of a methane intercepted graphene bilayer under a perpendicularly applied electric field. Evolution of the band structure of intercalated graphene as a function of the bias is studied by means of density-functional theory including interlayer van der Waals interactions. The implications of controllable band gap opening in methane-intercalated graphene for future device applications are discussed.     

新型分离技术——旋转带蒸馏

概述了旋转带蒸馏技术的特点,并详细介绍了旋转带蒸馏的装置结构、理论研究和应用现状。     

赵坡煤矿条带开采方案研究

赵坡煤矿村庄压煤量占矿井可采储量较大,为了矿井的生产和长远计划,在对地面房屋不产生影响或产生轻微影响情况下对压煤进行开采。根据区域地质开采条件及地表沉陷基本规律,分析了地表移动变形的基本特征,确定了研究区域12下、14、16、17四个煤层开采的地表移动变形合理计算参数,并进一步分析了村庄下压煤开采的基本途径,确定了村下开采方案和技术措施。通过运用数值模拟分析和开采方案综合分析,设计12下、14、16、17四个煤层条带法开采工作面的合理开采宽度。     

Distribution of Freshly Melted Glass in a Glass Band

The study analyzes the conditions of the distribution of the indicator (yttrium oxide introduced together with the batch) across and inside the glass band produced on top of molten metal. It is demonstrated that freshly melted tagged melt exists in the depth of the glass band in the form of luminescent layers, whose number increases with time, up to the uniform distribution of the indicator in the band. It is established that lateral convection in the glass melt has a determining effect on the distribution of tagged glass in the glass band.     

First-principles Studies of Band Gap Engineering in Ferroelectric Oxides

In the last decade there has been a resurgence of activity in the field of photoferroelectrics with a focus on the studies of oxides. Ferroelectric (FE) materials have a spontaneous switchable polarization that can lead to interesting light-matter interactions such as the bulk photovoltaic effect. While a wide range of compositions has been explored for ferroelectrics, until recently, FE oxides were considered to be capable of absorbing UV light only. Playing a key role in the advance of the field, first-principles calculations have guided the experimental materials discovery efforts that have identified a wide variety of visible-light-absorbing oxides. First-principles research efforts have also achieved considerable progress in revealing the interplay between the composition, structure and light absorption properties in these materials, and it is now understood that even small changes in the local environment can lead to large changes in band gap character and magnitude. Here, we survey the first-principles efforts following different band-gap engineering strategies and the advances in the computational methods that have been driven by these studies.     

Carriers Temperature Dependence of Energy Band Gap for Germanium

The carriers temperatures are calculated for each lattice temperature from 150 to 450 K for a germanium semiconductor. The effects of the electron-lattice and electron-phonon interactions are investigated and proved that the carriers temperatures are higher than the lattice temperatures. The energy gap at 0 K, E _g (0), was calculated using different methods and an average error of 1% was found between the calculated values and the literature. An approximate analytical expression was introduced to describe the temperature dependence of the energy gap using the carriers temperature as a parameter of characterization.     

Excitation Energy Evolution of Red-Luminescence Band in Porous Si

The excitation energy dependence of red-luminescence spectrum of porous Si prepared in different conditions is investigated in detail. The dependence has shown that the luminescence peak energy E_L of the porous Si nanoparticle is related to the bandgap E_g by E_L = 0.65 E_g+0.44 (eV). The relation has been explained from the model that holes in the Si nanoparticles excited by the interband excitation are trapped and then radiatively recombine with electrons in the conduction band.     

窄带隙半导体光催化材料研究进展

概述了窄带隙半导体光催化材料的光催化反应机理、新型窄带隙半导体光催化材料的种类以及影响窄带隙半导体光催化材料的光催化活性的因素.介绍了传统半导体光催化材料的掺杂改性方法和一些新型的窄带半导体光催化材料.     

机械管卡在海底管道维抢修中的应用

海底管道是海上油气田开发、生产与油气外输的主要设施。管道损坏事故多种多样,其中因施工缺陷、介质腐蚀、机械损伤等原因造成的管道变形、穿孔、裂缝、断裂腐蚀等损伤较为常见,在应急保护及修复该类损伤管道时较常采用机械管卡水下修复法。总结了国产机械管卡应用于水深小于60 m以下的海底管道损伤修复的通用做法,水深大于60 m的海底管道损伤修复工作也可以参考该方法。     

Ozone Generation with Narrow–Band UV Radiation

Ozone formation in oxygen at atmospheric pressure following the photodissociation of O₂ molecules in the vacuum UV range is tudied. A new VUV source based on incoherent xenon excimer radiation from a dielectric–barrier discharge provided narrow–band UV radiation at 172 nm with a half–width of 14 nm. The formation of ozone from the initial photodissociation fragments O(³P) and O(¹D) is treated theoretically and compared to measurements.     

单边带调制方式及DSP实现

本文介绍了目前单边带调制的模拟调制与数字调制的三种方法,着重介绍内插与抽取原理,数字单边带调制原理,以及DSP技术的实现。