六方体混凝土成型机在直岗拉卡水电站中的应用

文章针对直岗拉卡水电站土石坝工程中的六方体混凝土预制件，采用的混凝土成型机和采用常规的模具施工进行分析、对比。混凝土成型机在水工建筑等领域预制件的施工中具有较好的经济效益和推广前景。

外六方体加工方法探究

在中级钳工实训教学中,正确正六方体工件的加工,除要求操作者具有较高的技能水平和准确的精度测量以外,合理的安排加工工艺、充分的测量工具是保证加工出理想六方体的前提条件。本文阐述了以长方体为毛坯料时,六方体工件的划线和改进后的加工工艺方法。

一种六方体钳工加工方法研究

运用专业理论知识和实践经验,在总结了六方体钳工加工常见方法后,讨论了一种六方体钳工加工的新方法;并通过分析对比六方体钳工加工常见方法和新方法,研究如何进一步提高六方体的加工质量和缩短六方体的加工时间。

六方体加工的改进

在六方体的加工时,除掌握正确的加工方法,操作者的技巧水平能达到精度要求外,最重要的是利用量具对工件的尺寸精度、形位精度进行准确的测量。合理控制加工量,才能达到规定的各项精度要求,保证工件质量。采用简便易行的方法,解决测量中的疑难问题,保证测量的准确性和精确性,合理的修正加误差,是提高和保证工件质量的关键。本文阐述了六方体加工中测量方法的改进。

六方体的锉削加工工艺

为了保证六方体在配合时能正反翻边互换和转位互换,针对六方体中心是否有中心孔和提供的毛坯料形式不同,采用不同的加工方法,从而保证锉削加工六方体时六方体的6个120°角相等,且6条边的边长相等。

钳工基础操作锉削外六方体方法探讨

该论文主要讨论钳工锉削外六方体常用加工方法 ,从理论和专业知识谈起,对于如何进行六方体的加工,探讨如何提高其加工精度,并提出新的方法进行讨论。

锉刀柄部六方锥形体辊锻模具型面的3D共轭造型

基于空间啮合原理建立了锉刀柄部六方锥形体辊锻模型腔表面方程 ,推导了型腔表面端、轴截形的数学表达式 。

两种新的碳化硅长周期六方多型体240H和294H

多型性是结构化学和晶体学的一个极重要的现象和研究领域.许多密堆积或层状结构的无机化合物、页硅酸盐和矿物,例如SiC,ZnS,CdI_2,PbI_2,二硫族化合物、钙钛矿型结构化合物、粘土、云母,等等,都呈现广泛的多型性,可形成众多的结构变体或多型体.某些化合物多型体的堆积周期可达数千埃.出现如此巨大的结构周期确是结构化学领域中很值得研究的问题.碳化硅是最典型的多型性化合物,到目前为止,已发现有157种多型体.其中,我们发现了共84种SiC的多型体,占总数的一半以上.我们用倒易点阵点间关系法发现两种新的碳化硅长周期六方多型体240H和294H.

Signatures for Coexistence of Monoclinic and Hexagonal Phases in GaTe Nanoflakes

The burgeoning two-dimensional(2D)layered materials provide a powerful strategy to realize efficient light-emitting devices.Among them,gallium telluride(Ga Te)nanoflakes,showing strong photoluminescence(PL)emission from multilayer to bulk crystal,relax the stringent fabrication requirements of nanodevices.However,detailed knowledge on the optical properties of Ga Te varies as layer thickness is still missing.Here we perform thickness-dependent PL and Raman spectra,as well as temperature-dependent PL spectra of Ga Te nanoflakes.Spectral analysis reveals a spectroscopic signature for the coexistence of both the monoclinic and hexagonal phases in Ga Te nanoflakes.To understand the experimental results,we propose a crystal structure where the hexagonal phase is on the top and bottom of nanoflakes while the monoclinic phase is in the middle of the nanoflakes.On the basis of temperature-dependent PL spectra,the optical gap of the hexagonal phase is determined to be 1.849 eV,which can only survive under temperature higher than 200 K with the increasing phonon population.Furthermore,the strength of exciton-phonon interaction of the hexagonal phase is estimated to be 1.24 me V/K.Our results prove the coexistence of dual crystalline phases in multilayer Ga Te nanoflakes,which may provoke further exploration of phase transformation in Ga Te materials,as well as new applications in 2D light-emitting diodes and heterostructure-based optoelectronics.

Identification and Typing of Respiratory Adenoviruses in Guangzhou, Southern China Using a Rapid and Simple Method

Human adenoviruses (HAdVs), especially HAdV-B3, -E4 and -B7, are associated with Acute Respiratory Disease in Chinese children, and occasionally in adults. In order to establish and document the profiles of the respiratory adenovirus pathogen among children in Guangzhou, Southern China, a rapid, simple and practical method for identification and typing of respiratory adenoviruses was developed and evaluated. One pair of universal PCR primers was designed according to the conserved region of the hexon gene, which can detect not only HAdV-B3, -E4 and -B7, but also HAdV-B14, -F40 and -F41, with a specific 300bp PCR product. Three pairs of type-specific PCR primers were also designed according to the hypervariable regions of the hexon gene to type HAdV-B3, -E4 and -B7 by three independent PCR reactions, making it easy to optimize the PCR conditions. By using this method, one hundred throat swab specimens collected during Oct 2010 to Dec 2011 and suspected of being positive for adenoviral infection were identified and typed for adenoviruses. Of these samples, fifty-five were adenovirus-positive. The most common HAdV type was HAdV-B3, identified in 92.7% of samples, which is not only consistent with the data reported in 2004-2006, but also consistent with the recent report in Hangzhou, eastern China, indicating that HAdV-B3 has been circulating in Guangzhou, and maybe in eastern China, for many years. The method for the respiratory adenovirus identification and typing we developed is rapid, simple and practical, which has a potential in the real-time surveillance of circulating adenovirus strains and also to provide etiological evidence for the adenovirus-relative disease control and prevention in China.

Polarization of plane wave propagating inside elastic hexagonal system solids

Based on the reported physical parameters for hexagonal system solids,we have calculated the effects of anisotropy on polarization of plane P-wave propagation.Herein we report the results of calculations and the newly observed physical phenomena.It is found that,for a given propagation,if the polarization is parallel to the wave vector,so also to the Poynting vector.In such a case,the phase velocity is identical to the energy velocity;the quasi P-wave degenerates to a pure P-wave along the propagation.It is also noted that if the polarization is parallel to the Poynting vector but not to the wave vector,the propagating wave cannot be a pure P-wave.Furthermore,the polarization in a quasi P-wave may deviate from the wave vector for more than 45°,but the deviation from the Poynting vector is always less than 45°.The energy velocity of a quasi SV-wave can be larger than that of the quasi P-wave in some propagation directions,even though the phase velocity of a quasi SV-wave may never be larger than either the phase velocity or energy velocity of the quasi P-wave.Finally,in case of parameters ε=0 and δ*≠0,the polarization of a quasi P-wave has an observed symmetry at a 45°phase angle.The anisotropy of a hexagonal system solid determines if a pure P-wave can be created and what the propagation direction is for a plane wave propagating inside such a hexagonal system solid.

Enhanced photochemical performance of hexagonal WO_3 by metal-assisted S–O coupling for solar-driven water splitting

Hybrid density functional calculations was used to comprehensively study the electronic structure of S-,Snand Pb-monodoped and（Sn,S）-and（Pb,S）-codoped hexagonal WO_3（h-WO_3）in order to improve their visible light photocatalytic activity.Results indicate that the（Sn,S）-and（Pb,S）-codoped h-WO_3 can realize a significant band gap reduction and prevent the formation of empty states in the valence band of h-WO_3,while Sn/Pb-monodoped h-WO_3 cannot,because in（Sn,S）-and（Pb,S）-codoping,the S-doping introduces the fully occupied S 3p states in the forbidden band gap of h-WO_3 and the acceptor metals（Sn and Pb）would assist the coupling of the introduced S with its nearest O.In particular,the（Sn,S）-codoped h-WO_3 has the narrowest band gap of 1.85 eV and highest reducing ability among the doped case.Moreover,the calculated optical absorption spectra show that（Sn,S）-codoping can improve the visible light absorption.In short,these results indicate that the（Sn,S）-codoped h-WO_3 is a promising material in solar-driven water splitting.

Thickness-stretch vibration of a crystal plate carrying a micro-rod array

We analyze thickness-stretch vibrations of a plate of hexagonal crystal carrying an array of micro-rods with their bottoms fixed to the top surface of the plate.The rods undergo longitudinal vibrations when the crystal plate is in thickness-stretch motion.The plate is modeled by the theory of anisotropic elasticity.The rods are modeled by the one-dimensional structural theory for extensional vibration of rods.A frequency equation is obtained and solved using perturbation method.The effect of the rod array on the resonant frequencies of the crystal plate is examined.The results are potentially useful for using thickness-stretch modes of crystal plates to measure the mechanical properties of microrod arrays.