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991.
Based on the concept of functionally graded concrete, UHTCC (ultrahigh toughness cementitious composites) material with excellent
crack-controlling ability is strategically substituted for part of the concrete, which surrounds the main longitudinal reinforcement
in a reinforced concrete member. Investigations on bending behavior of such a functionally graded composite beam crack-controlled
by UHTCC (abbreviated as UHTCC-FGC beam) have been carried out. After establishing a theoretical calculation model, the paper
discusses the results of four-point bending experiment on long composite beams without web reinforcement, and validates the
theoretical formulae through experimental results of UHTCC-FGC beams with different thicknesses of UHTCC layer. Besides improving
bearing capacity and saving steel reinforcements, the results indicate that UHTCC-FGC beams can also effectively control the
deformation and enhance the ductility of members. At last, the optimal thickness of UHTCC layer in UHTCC-FGC beams has been
confirmed, which can not only save materials and improve mechanical performance of members, but also be very effective in
preventing corrosion-induced damage and enhancing the durability of members by controlling crack width below 0.05 mm under
service conditions.
Supported by the Key Program of the National Natural Science Foundation of China (Grant No. 50438010) and the Research and
Application Programs of Key Technologies for Major Constructions in the South-North Water Transfer Project Construction in
China (Grant No. JGZXJJ2006-13) 相似文献
992.
Yu Tian JianZhong Wang WeiFeng Yu RongGen Cao Yun Song XiJing Ning 《中国科学E辑(英文版)》2009,52(6):1698-1702
Electrochemical deposition method was employed to prepare CNx thin film from methanol-urea solution,and it was shown that adding a little acetic acid in the solution significantly affected the deposition process.After optimizing the experiment conditions,we obtained polycrystalline grains with sizes of about 3―7μm on the faces of single crystal silicon.X-ray diffraction spectrua indicate that the grains are mainly composed of cubic phase mixed with a small amount of β and α phases. 相似文献
993.
Synthetic aperture interferometric technique has wide applications in optics, radio astronomy and microwave remote sensing
areas. With the increasing demands of high resolution imaging observation, a new time-sharing sampling scheme of asynchronous
rotation scan is proposed to meet the technical challenge of achieving a large equivalent aperture and overcome the operating
barriers of space borne application. This configuration is basically composed by two asynchronously and concentrically rotating
antenna groups, whose revolving radii and speeds are different. The synthetic aperture system with asynchronous rotation scanning
scheme can effectively solve the trade-off problem of system complexity, and greatly simplify the system hardware at the cost
of sacrificing a certain time resolution. The basic rules and design methods of asynchronous rotation scan are investigated
The Gridding method is introduced to inverse the spiral sampling data for image reconstruction. The potential applications
of geostationary orbit (GEO) earth observation and solar polar orbit (SPO) plasma cloud observation are explored with numerical
simulations to validate the significance and feasibility of this new imaging configuration.
Supported by the National Natural Science Foundation of China (Grant No. 40574070, 40671121, 40701100 and 40801136) and the
National High-Tech Research Program of China (“863” Program) (Grant No. 2006AA12Z141) 相似文献
994.
Experiments of simultaneous removal of SO2 and NO from simulated flue gas, using NaClO2 solution as the absorbent, were carried out in a self-designed bubble reactor, and high simultaneous removal efficiencies
of SO2 and NO were obtained under the optimal experimental conditions. The mechanism of simultaneous removal based on NaClO2 acid solutions was proposed by analyzing the removal products. Possibility and limitation of the desulfurization and denitrification
using NaClO2 acid solutions were calculated by thermodynamic methods. Experimental results of reaction kinetics for simultaneous desulfurization
and denitrification indicated that the oxidation-absorption processes of SO2 and NO were divided into two zones, namely the fast and slow reaction zones. In the slow reaction zones both were zero order
reactions, and in the fast reaction zones, the reaction order, rate constant and activation energy of SO2 reaction with absorbent were 1.4, 1.22 (mol·L−1)−0.4·s−1 and 66.25 kJ·mol−1, respectively, and 2, 3.15×103 (mol·L−1) −1·s−1, and 42.50 kJ·mol−1 for NO reaction, respectively.
Supported by the National High-Tech Research and Development Program of China (“863” Project) (Grant No. 2007AA061803) 相似文献
995.
A systemic process study on an electron beam nanolithography system operating at 100 kV was present. The exposure conditions
were optimized for resist ZEP520A. Grating structures with line/space of 50 nm/50 nm were obtained in a reasonably thick resist
which is beneficial to the subsequent pattern transfer technique. The ICP etching process conditions was optimized. The role
of etching parameters such as source power, gas pressure, and gas flow rate on the etching result was also discussed. A grating
structure with line widths as small as 100 nm, duty cycles of 0.5, depth of 900 nm, and the side-wall scalloping as small
as 5 nm on a silicon substrate was obtained. The silicon deep etching technique for structure sizes smaller than 100 nm is
very important for the fabrication of nano-optical devices working in the visible regime.
Supported by the National Basic Research Program of China (“973” Program) (Grant No. 2007CB935301) 相似文献
996.
Multi-channel micro neural probe fabricated with SOI 总被引:1,自引:0,他引:1
WeiHua Pei Lin Zhu ShuJing Wang Kai Guo Jun Tang Xu Zhang Lin Lu ShangKai Gao HongDa Chen 《中国科学E辑(英文版)》2009,52(5):1187-1190
Silicon-on-insulator(SOI) substrate is widely used in micro-electro-mechanical systems(MEMS).With the buried oxide layer of SOI acting as an etching stop,silicon based micro neural probe can be fabri-cated with improved uniformity and manufacturability.A seven-record-site neural probe was formed by inductive-coupled plasma(ICP) dry etching of an SOI substrate.The thickness of the probe is 15 μm.The shaft of the probe has dimensions of 3 mm×100 μm×15 μm with typical area of the record site of 78.5 μm2.The im... 相似文献
997.
After the 5.12 Wenchuan Earthquake which took place on May 12, 2008, aerial remote sensing has rapidly covered all the influence
sites of the earthquake, emergency aero-photo interpretation has revealed the disaster distribution limitation, and captured
the information of location, dimension of the destroyed houses, roads and other structures, blocked rivers, etc, which provided
destroying conditions of the time for rescuing lives, rebuilding traffic lines and estimating disaster situation. The further
interpretation and analysis indicate that large scale second growth geological disasters mainly distribute in the distance
of 0–300 km and 45°–50° orientation from the epicenter. About 137 latent large-scale landslides and debris-flows will occur
in this rain season and coming several years, so how to avoid current geological disasters as well as the latent large disasters
should be considered in making rebuilding and developing plan. 相似文献
998.
The electronic structures of kinks in the [100](010) and 1/2[111](−110) edge dislocations in bcc iron containing hydrogen
are investigated by means of the first-principles DMol method and the discrete variational method. The effects of hydrogen
on the kinks are discussed. The results show that hydrogen forms weak bonding states with its neighboring host atoms, and
since hydrogen draws charge from its neighboring host atoms, the interactions between most of the host atoms are weakened
compared with those of the corresponding atomic pairs in the clean kinks. This indicates that the migration of kink, i.e.
the motion of dislocation, is easier in the doping hydrogen kink than in the clean kink, which may be the solid solution softening
effect resulting from the impurity hydrogen.
Supported by the National Basic Research Program of China (Grant No. 2006CB605102) and Science Foundation of Central South
University of Forestry & Technology (Grant No. 06y016) 相似文献
999.
The L, H and C curves in P-T phase are proposed to describe the minimal, maximal and critical characteristics of ignition time of H2/O2 combustion system, respectively. The features of H2/O2(Air) combustion system, including explosion or not as well as the time delay to achieve its explosion status, can be well
shown by explosion limits and these proposed curves. These curves can be described by 1.2k
1=k
s
[Ms], (k
11/k
10+1)k
1=k
s
[Ms], and 2k
1=k
s
[Ms], respectively, which provide a physical explanation for these curves and give another way to establish them. Based on the
contour of ignition time, the Z-type explosion limits can be explained by thermal explosion theory. Furthermore, the ignition
distance of supersonic combustion is predicted according to the ignition time obtained in a Semenov system, which is very
reasonable. 相似文献
1000.
In remote sensing applications, accurate extraction of land type area after classification is very important. But for images
of land use/cover change (LUCC) obtained from the special spatial resolution remote sensing data, it will be of great significance
to obtain the land type area information with higher resolution by making use of spatial distribution characteristcs information
of the land type itself first and further scaling-down in a given scale threshold on the basis of the existing spatial resolution
data. An explicit expression of the relationship between the measurement scale, global fractal dimension and the land type
area corresponding to different measurement scales is obtained on the research basis of the authors’ histo-variogram using
the standardized area index (SAI). A good attempt has been made to obtain the land type area information with higher resolution
by merely using the spatial distribution characteristcs information of the land type in the image itself and further scaling-down
in a given scale threshold on the basis of the existing spatial resolution data.
Supported by the National Natural Science Foundation of China (Grant No. 40601068), the National Basic Research Program of
China (“973” Project) (Grant No. 2007CB714402) and the Key Science and Technology R&D Program of Qinghai Province (Grant No.
2006-6-160-01) 相似文献