浆砌石衬砌在渠道防渗中的应用及对策

总结了浆砌石应用的历史,介绍了浆砌石的结构特性和施工工艺,从造价方面、防渗效果及施工三方面分析了浆砌石衬砌主要存在的问题,并提出了相应的解决对策,指出浆砌石衬砌在渠道防渗应用中应控制施工质量,从而更好地提高防渗效果。

浅析渠道防渗中浆砌石衬砌的实践和应用

在现代建筑中,渠道作为一项主要的并且重要的项目出现,受到人们的高度重视,渠道防渗衬砌是灌区提高输水效益的有效途径,防渗工作质量的好坏直接决定着整个渠道施工质量的好坏。因此,本文就从渠道防渗中浆砌石衬砌存在的问题以及应用进行分析,浅析渠道防渗中浆砌石衬砌的实践和应用。

基于相对差异函数的砌石隧道安全性评价

砌石衬砌隧道作为铁路线路上的重要工程,运营过程中受到多种因素的共同作用,隧道内经常出现影响运营安全的衬砌病害。以成都局砌石衬砌病害资料为基础,统计分析砌石衬砌病害分布情况,根据层次分析法原理建立了砌石衬砌隧道安全评价指标体系,引入相对差异函数确定指标对各安全等级的隶属度,通过可变识别模型计算砌石衬砌隧道的安全评价值。通过对典型隧道进行评价表明,引入相对差异函数对砌石衬砌隧道安全进行评价是可行的,而且评价结果更加合理,可为砌石衬砌隧道的维护提供依据。

GENETIC OPTIMIZATION OF HOT FILAMENT PARAMETERS IN HFCVD SYSTEM

In HFCVD system the substrate temperature is a key factor which deeply affects the quality of diamond films. Th e magnitude and the variation of the substrate temperature must be limited in a suitable range to deposit diamond films of uniform thickness over large areas. In this paper, the hot filament parameters are investigated on the basi s of GAs to realize a good substrate temperature profile. Computer simulations d emonstrate that on parameters optimized by GAs a uniform substrate temperatur e field can be formed over a relatively large circle area with R s=10 cm.

浆砌石土工膜防渗技术在渠道防渗中的应用

在当前我国的很多建筑里面,渠道防渗施工已经成为了一项十分主要并且不可或缺的项目,使其受到了人们普遍的关注与重视,渠道的防渗衬砌可以说是灌区对于输水效益加以提升的科学方式,防渗工作质量自身进行的好不好直接对整体渠道施工质量的好坏产生了很大的影响。所以,本文就主要针对渠道防渗里浆砌石衬砌在进行使用过程中出现的问题还有予以分析,对于渠道防渗里浆砌石衬砌的具体施工以及使用进行分析。

浅谈渠道防渗工程措施及其施工技术

渠道采取防渗工程措施不仅可以减少输水渗漏量,还可以适当提高渠道的抗冲刷能力,减小糙率,增大渠道的过流能力,提升渠道灌溉用水利用系数。本文根据在灌区渠道改造中的施工经验,总结了不同形式的渠道防渗工程措施及其施工技术,以供同类工程借鉴参考。

汾东干渠防渗技术施工工艺研究

汾河灌区在续建配套与节水改造过程中,针对汾东灌区的不同地段渠道不同的特点,因地制宜采用三种渠道防渗技术的施工工艺,通过采取防渗措施,使渠道防渗标准和渠系水有效利用系数得到提高,取得了显著的节水效果,该施工工艺可为同类工程提供参考。

永记灌区两种渠道防渗技术的施工工艺

简述了永记灌区在续建配套与节水改造过程中,采用钢筋混凝土衬砌和浆砌石挡土墙衬砌两种渠道防渗技术的施工工艺。

Study on the propagation of interface crack of young concrete lining and rock under blasting load

In the construction of water conservancy and hydropower project,young concrete lining structure is often affected by blasting load. Young concrete has a lot of micro-fractures with random distribution,which are easier to propagate and connect under blasting load. This paper focuses on the calculation on dynamic stress intensity factors of bond interface crack of concrete-rock according to concrete age. Result shows that different incidence angles of stress wave lead to different crack propagation mechanisms. Under the normal incidence of impact load,the bonding interface crack propagation of the concrete lining is mainly caused by reflection tensile stress,which forms from the free surface. With horizontal incidence of stress wave,the bond interface crack propagation of concrete lining is affected by concrete age. With the increase of concrete age,the elasticity modulus margin between concrete and rock decreases gradually,and the crack propagation form changes from shear failure to tensile damage.

GaN-based light emitting diodes on nano-hole patterned sapphire substrate prepared by three-beam laser interference lithography

Nano-hole patterned sapphire substrates （NHPSSs） were successfully prepared using a low-cost and high-efficiency approach, which is the laser interference lithography （LIL） combined with reactive ion etching （RIE） and inductively coupled plasma （ICP） techniques. Gallium nitride （GaN）-based light emitting diode （LED） structure was grown on NHPSS by metal organic chemical vapor deposition （MOCVD）. Photoluminescence （PL） measurement was conducted to compare the luminescence efficiency of the GaN-based LED structure grown on NHPSS （＇NHPSS-LED） and that on unpatterned sapphire substrates （UPSS-LED）. Electroluminescence （EL） measurement shows that the output power of NHPSS-LED is 2.3 times as high as that of UPSS-LED with an injection current of 150 mA. Both PL and EL results imply that NHPSS has an advantage in improving the crystalline quality of Gab/epilayer and light extraction efficiency of LEDs at the same time.

灌溉渠道防渗衬砌在江川县烟田基础建设中的应用

针对烟田建设的现状，作者阐述了渠道防渗在烟田灌溉中的必要性，重点介绍了渠道防渗衬砌的二种类型应用情况。

Effects of substrate and transfer on CVD-grown graphene over sapphire-induced Cu films

We differentiated the effects of Cu films deposited on single crystalline a-,r-,and c-plane sapphire substrates upon graphene films synthesized with atmospheric pressure chemical vapor deposition(CVD).The data illustrate that the realization of high-crystalline Cu film is dependent not only on the crystallinity of underlying substrate,but also on the symmetric match of crystallographic geometry between metal film and substrate.We also systematically investigated the effects of PMMA removal on the Raman ID/IG and IG/I2D values of transferred graphene.The results reveal that different PMMA removal methods do not alter the ID/IG values;instead,the residue of PMMA increases the IG/I2D values and the thermal decomposition of PMMA leads to higher IG/I2D values than the removal of PMMA with acetone.The effects of PMMA removal on variations of the Raman spectra are also discussed.

Study on growing thick AlGaN layer on c-plane sapphire substrate and free-standing GaN substrate

In this study,the thick AlGaN epilayers have been grown on the c-plane sapphire substrate and the free-standing GaN substrate using low-temperature AlN nucleation layers by low-pressure metal-organic chemical vapor deposition(LPMOCVD).High resolution X-ray diffraction(HRXRD),atom force microscopy(AFM),scanning electron microscopy(SEM),photoluminescence(PL) and Raman scattering measurements have been employed to study the crystal quality,threading dislocation density,surface morphology,optical properties and phonon properties of thick AlGaN epifilms.The results indicate that AlGaN epifilms crystal quality can be improved greatly when grown on the free-standing GaN substrate.We calculated the threading dislocation density and found that thick AlGaN epifilm grown on the free-standing GaN substrate is much lower in total threading dislocation density than that grown on the sapphire substrate,although the surface morphology is rougher than that of sapphire substrate.

Ultrawide-bandgap(6.14 eV)(AlGa))_(2)O_(3)/Ga_(2)O_(3)heterostructure designed by lattice matching strategy for highly sensitive vacuum ultraviolet photodetection

One judiciously designed strategy of utilizing an ultrathin but conductive Ga_(2)O_(3):Si nanolayer to prepare(AlGa)_(2)O_(3)crystalline film is demonstrated.Benefiting from the existence of Ga_(2)O_(3):Si nanolayer,a high-quality(Al_(0.68)Ga_(0.32))_(2)O_(3)sesquioxide film with 68 at.%aluminum was epitaxially grown on sapphire substrates,which was characterized by high-resolution transmission electron microscopy,X-ray photoelectron spectroscopy and X-ray diffraction.Its bandgap was broadened to 6.14 eV,and a vacuum ultraviolet(VUV)(AlGa)_(2)O_(3)/Ga_(2)O_(3):Si photodetector was subsequently fabricated.The detector exhibits a pretty high on-off ratio of about 10^(3),an open-circuit voltage of 1.0 V and a responsivity of 8.1 mA W^(-1) at 0 V bias voltage.The performances imply that the proposed strategy is valuable for improving the quality and also adjusting the bandgap of(AlGa)_(2)O_(3)sesquioxides,which is expected to facilitate their application in VUV photodetection.

Investigation of thermal radiation effect on optical dome of sapphire coated yttrium oxide

Compared to traditional optical domes, domes of sapphire coated with films can effectively reduce emissivity and increase transmittance. The purpose of this work is to investigate the thermal radiation effect on sapphire optical dome coated with yttrium oxide by a radio frequency mag- netron sputtering method. The emissivity of sapphire coated with Y203 films is studied by both numerical and experi- mental methods. The results indicate that the emissivity of sapphire substrate is reduced effectively with increasing the thickness of the Y203 film. In addition, a finite element model is developed to simulate the radiation intensity of the optical dome. The thermal responses indicate that the max- imum temperature is reduced apparently compared with the uncoated sapphire as Y203 film thicknesses increase. The average irradiance distribution at different film thicknesses with time shows that the self-thermal radiation disturbance of sapphire optical dome delays 0.93 s when the thickness of Y203 film is 200μm, which can guarantee the dome works properly and effectively even in a harsh environment.

Synthesis of monoclinic structure gallium oxide film on sapphire substrate by magnetron sputtering

Gallium oxide （Ga203） films were deposited on singlecrystalline sapphire （0001） substrate by radio frequency （RF） magnetron sputtering technique in the temperature range of 300--500 ℃. The microstructure of the fl-Ga203 films were investigated in detail using X-ray diffractometer （XRD） and scanning electron microscope （SEM）. The results show that the film prepared at 500℃ exhibits the best crystallinity with a monoclinic structure （fl-Ga203）. Structure analysis reveals a clear out-of-plane orientation offl-Ga203 （201） II A1203 （0001）. The average transmittance of these films in the visible wavelength range exceeds 90%, and the optical band gap of the films varies from 4.68 eV to 4.94 eV which were measured by an ultraviolet-visible-near infrared （UV-vis-NIR） spectrophotometer. Therefore, it is hopeful that the fl-Ga203 film can be used in the UV optoelectronic devices.

Ultrahigh Density Modulation of Aligned Single-Walled Carbon Nanotube Arrays

Controlling the densities of aligned single-walled carbon nanotube arrays （SWNTs） on ST-cut quartz is a critical step in various applications of these materials. However the growth mechanism for tuning SWNT density using the chemical vapor deposition （CVD） method is still not well understood, preventing the development of efficient ways to obtain the desired results. Here we report a general ＂periodic＂ approach that achieves ultrahigh density modulation of SWNT arrays on ST-cut quartz substrates--with densities increased by up to -60 times compared with conventional methods using the same catalyst densities--by varying the CH4 gas ＂off＂ time. This approach is applicable to a wide range of initial catalyst densities, substrates, catalyst types and growth conditions. We propose a general mechanism for the catalyst size-dependent nucleation of SWNTs associated with different free carbon concentrations, which explains all the observations. Moreover, the validity of the model is supported by systematic experiments involving the variation of key parameters in the ＂periodic＂ CVD approach.

Enhanced Raman scattering of graphene on Ag nanoislands

The effect of Ag nanoislands on the Raman of graphene was investigated in this work.Compared with that on the bare silicon wafer,Raman enhancement was observed in the graphene film that covered on Ag/Si surface with nanoscale Ag islands,which would be induced by the localized plasmon resonance in Ag nanostructures.The interaction between the graphene sheet and Ag/Si substrate was further studied.The peak shift and line shape of Raman spectroscopy indicated a nonuniform strain distribution in the Ag/Si supported graphene film.

Formation mechanism of subtrenches on cone-shaped patterned sapphire substrate

In this paper, the cone-shaped patterned sapphire substrates (PSS) were etched by an inductively couple plasma with BCl 3 as the reacting gas. The influence of the operating pressure and the RF bias power on subtrenches of the cone-shaped PSS and the formation mechanism of subtrenches were investigated. The profiles of patterns were characterized by FESEM (field emission scanning electron microscope). It showed that the subtrench size varied with the operating pressure and the RF bias power. As the operating pressure increased from 0.2 Pa to 0.9 Pa, the subtrenches changed from narrow and deep to wide and shallow; then to narrower and shallower. When the RF bias power varied from 200 W to 600 W, the subtrenches gradually became noticeable. The FESEM results also indicated that the subtrenches were formed due to the ion scattering effect which was caused by tapered sidewalls and charges accumulation. It is discovered that the scattering effect is closely related with the operating pressure and RF bias power.