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1.
Uniaxial compression experiments on horizontal and vertical samples of first-year freshwater ice in a res- ervoir were conducted at different temperatures and strain rates with an electronic universal machine equipped with low temperature cabinet. The results show that there is no difference between the strengths of two horizontal samples with grain sizes ranging from 1 to 4,mm and 4 to 14,mm, while the strength of the 1-4 mm vertical samples is 1.4 times higher than that of the 4-14 mm vertical samples because of the change of crystal structure. For different loading directions, the strengths of the horizontal samples do not differ from those of the vertical samples with the same grain sizes. The relation among the uniaxial compressive strength, strain rate and temperature was established through data analysis in both the ductile and brittle regions. 相似文献
2.
To improve the processing efficiency and the quality of orbital milling hole of aerospace Al-alloy, the big-pitch influence on cutting force and hole quality was studied experimentally. First, a program based on horizontal lathe was proposed based on kinematics analysis of orbital milling. Then, the cutting force at different stages and the hole quality with different pitches were measured. Results show that the axial force and radial force increase with the pitch amplification during orbital milling. However, the axial force in the orbital milling hole is about 8—10 times smaller than that in the conventional drilling. The diameter error of milling hole is 48—93 μm, and the surface roughness of milling hole is 1.2—1.7 μm. Finally, an orbital milling device with big pitch was designed. 相似文献
3.
The clock generator and OOK modulator for RFID (Radio Frequency Identification) presented in this paper consist of a current source and delay elements. The simple constant-gm structure is adopted in the current source design and the current consumption of the current source is only about 2 μA. The delay elements, the clock generator and OOK modulator are introduced in detail in the paper. The designed circuits are fabricated by 0.6 μm CMOS process. The area of the core circuit is only about 400 μmμ0 μm. The delay time of all three samples is in the range of 9 μs to 21 μs when the supply voltage varies from 2 V to 4 V. As the measured results satisfy the system requirements, these circuit structures are suitable for RFID application. 相似文献
4.
1Introduction Generally,ultrafiltration(UF)asaseparationtech nologyofhighefficiencyandlowenergyconsumption haswidelybeenappliedinvariousindustries.Inin dustrialapplications,therearesixbasicUF modules[1]:(1)tubular,withinnerchannel diameters>4mm;(2)hollowfibers,withinnerdia metersof0.2-3mm;(3)plateunits;(4)spiral woundmodules;(5)pleated sheetcartridges;and(6)rotarymodules.However,hollowfiberUFmoduleis oneofmostimportantmodulesbecauseofitshigh areapackingdensity.Besides,UFtechnologyalsois us… 相似文献
5.
SUN Lin zhi SUN Ping WANG Cun min QIN Xin jie 《上海大学学报(英文版)》1999,3(4):308-312
１ Ｉｎｔｒｏｄｕｃｔｉｏｎ Ｍｉｌｌｉｍｅｔｅｒｓｉｚｅｍｉｃｒｏｍａｃｈｉｎｅｓｂａｓｅｄｏｎｍｏｄｅｒｎｐｒｅｃｉｓｉｏｎｍａｃｈｉｎｉｎｇｈａｖｅｐｏｔｅｎｔｉａｌａｐｐｌｉｃａｔｉｏｎｉｎｉｎｄｕｓｔｒｙ．Ｓｏｍｅｎａｒｒｏｗｓｐａｃｅｓｏｒｓｍａｌｌａｒｅａｓｎｅｅｄｔｈｅｓｅｍｉｃｒｏｍａｃｈｉｎｅｓｔｏｉｎｓｐｅｃｔａｎｄｒｅｐａｉｒｄｅｆｅｃｔｓ．Ｒｅｓｅａｒｃｈｅｒｓｈａｖｅｗｏｒｋｅｄｏｎｆａｂｒｉｃａｔｉｏｎｏｆｖａｒｉｅｄｖｅｈｉｃｌｅｓｗｉｔｈｗｈｅｅｌｓ,ｍｏｂ… 相似文献
6.
In order to design birefringent holey fiber with beat-length independent of wavelength, an asymmetric structure is introduced to reduce its wavelength-sensitivity. The influence of structural parameters on the modal birefringence is calculated and analyzed. After optimizing the parameters, a flat dispersion curve of beat-length is obtained. The beat-length changes from 89.8 mm to 91.0 mm in wavelength range from 1.1 μm, to 1.7 μm, and its relative variation is 1.38%. If this fiber is made into zero-order qu... 相似文献
7.
It is required to develop micro-machine for inspection and maintenance of defects inside small pipe withdiameter smaller than one inch. Considering the advantages of electromagnetic actuators with simple mechanism,high response, convenience to control and fabricate, we tried to develop a new micro-robot in small pipe based on in-teraction principle of electromagnetic attraction and spring force. This paper describes its structure and design. Thedimension of the prototype is diameter of 15 mm, length of 30 mm and weight of 25 g. It can climb in small pipe ofdiameter of 20 mm with a speed of 6～8 mm/s in horizontal or in vertical situation. 相似文献
8.
INTRODUCTION With the development of modern electronics,there is a growing trend of designing a low-voltagehigh precision current reference in many mixed-signaland analog circuits such as data converters (Mehr andSinger, 2000; Oh et al., 2004), oscillators and PLLs(Razavi, 2001; Banba and Shiga, 1999). Low-costreasons need the reference to be realized in simplestandard CMOS logic process technology, withoutresorting to the use of BiCMOS process and specialdevices such as floating-g… 相似文献
9.
Gas-solid two-phase turbulent plane jet is applied to many natural situations and in engineering systems. To predict the particle
dispersion in the gas jet is of great importance in industrial applications and in the designing of engineering systems. A
large eddy simulation of the two-phase plane jet was conducted to investigate the particle dispersion patterns. The particles
with Stokes numbers equal to 0.0028, 0.3, 2.5, 28 (corresponding to particle diameter 1 μm, 10μm, 30μm, 100μm, respectively)
inRe=11 300 gas flow were studied. The simulation results of gas phase motion agreed well with previous experimental results.
And the simulation results of the solid particles motion showed that particles with different Stokes number have different
spatial dispersion; and that particles with intermediate Stokes number have the largest dispersion ratio.
Project (No. G19990222) supported by the Special Funds for Major State Basic Research of China 相似文献
10.
Raman lasers based on potassium gadolinium tungstate and lead tungstate crystals pumped bya≈120 ps Nd: YAG laser at 1.064 μm were developed. High reflection mirrors for the Stokes wavelength have been used to generate
near-infrared and eye safe spectral region of 1.15–1.32 μm. Second harmonic generation of the generated Raman lasers was observed.
Eifficient multiple Stokes and anti-Stokes picosecond generation in 64 crystals have been shown to exhibit stimulated Raman
scattering on about 700 lines covering the whole visible and near-infrared spectrum. All stimulated Raman scattering (SRS)
wavelengths in the visible and near-infrared spectrum are identified and attributed to the SRS-active vibration modes of these
crystals. 相似文献
11.
Objective: To study the effects of different concentrations of antisense oligodeoxynucleotides (ASODN) on human pancreatic
cancer cell line PaTu8988s. Method: Human pancreatic cancer cell line PaTu8988s in exponential growth stage was used to study
the effect of different drug concentrations on the cell line in the presence of different concentrations (0 μg/ml, 5 μg/ml,
25 μg/ml, 50 μg/ml, 10 μg/m, 200 μg/ml) of ASODN and sense oligodeoxynucleotides (SODN). Cell counts and 3-[4,5-dimethylthiazolzyl]-2,5-diphenyl
tetrazolium bromide (MTT) assays were carried out. Results: The inhibitory rate on the cell line PaTu8988s was 98.73%, 95.76%,
69.49%, 33.05% and 0 for ASODM concentrations of 200 μg/ml, 100 μg/ml, 50 μg/ml, 25 μg/ml and 5 μg/ml at 48 hours. Conclusions:
K-ras complementary ASODN can inhibit the growth of human pancreatic cancer cell line PaTu8988s by 30.05% to 98.73%. This
is likely to contribute to the specificity of the K-ras mRNA complementary capped ASODN sequential codon. Non-specific effect
and side effect of ASOND were observed for instance, the greater the concentration is, the earlier the peak of inhibitory
rate is reached. In concentration, of 25 μg/ml to 100 μg/ml ASODN showed a dose-effect correlation. 相似文献
12.
Experiments and sensitivity analyses for heat transfer in a meter-scale regularly fractured granite model with water flow 总被引：1，自引：0，他引：1
Experiments of saturated water flow and heat transfer were conducted for a meter-scale model of regularly fractured granite. The fractured rock model (height 1502.5 mm, width 904 mm, and thickness 300 mm), embedded with two vertical and two horizontal fractures of pre-set apertures, was constructed using 18 pieces of intact granite. The granite was taken from a site currently being investigated for a high-level nuclear waste repository in China. The experiments involved different heat source temperatures and vertical water fluxes in the embedded fractures either open or filled with sand. A finite difference scheme and computer code for calculation of water flow and heat transfer in regularly fractured rocks was developed, verified against both the experimental data and calculations from the TOUGH2 code, and employed for parametric sensitivity analyses. The experiments revealed that, among other things, the temperature distribution was influenced by water flow in the fractures, especially the water flow in the vertical fracture adjacent to the heat source, and that the heat conduction between the neighboring rock blocks in the model with sand-filled fractures was enhanced by the sand, with larger range of influence of the heat source and longer time for approaching asymptotic steady-state than those of the model with open fractures. The temperatures from the experiments were in general slightly smaller than those from the numerical calculations, probably due to the fact that a certain amount of outward heat transfer at the model perimeter was unavoidable in the experiments. The parametric sensitivity analyses indicated that the temperature distribution was highly sensitive to water flow in the fractures, and the water temperature in the vertical fracture adjacent to the heat source was rather insensitive to water flow in other fractures. 相似文献
13.
Objective: To prepare microencapsulated cells releasing human tissue inhibitor of metalloproteinase-2 (TIMP-2), and investigate
their biological characteristics in vitro. Methods: Chinese hamster ovary (CHO) cells were stably transfected with a human
TIMP-2 expression vector, encapsulated in barium alginate microcapsules and cultured in vitro. Morphological appearance of
the microcapsules was observed under a light microscope. Cell viability was assessed using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide) assay. Enzyme linked immunosorbent assay (ELISA) and reverse zymography were used to confirm the release of biologically
active TIMP-2 from the microcapsules. Cryopreservation study of the microencapsulated cells was carried out using dimethyl
sulfoxide (DMSO) as preservative agent. Results: The microcapsules appeared like a sphere with diameter of 300–600 μm. The
surface of the capsule wall was clearly smooth. The microencapsulated cells survived well and kept proliferating over the
6 weeks observed. No significant difference in TIMP-2 secretion was found between encapsulated and unencapsulated cells. Reverse
zymography confirmed the bioactivity of MMP (matrix metalloproteinase) inhibition of TIMP-2. The cryopreservation process
did not damage the microcapsule morphology nor the viability of the cells inside. Conclusion: Microencapsulated engineered
CHO cells survive at least 6 weeks after preparation in vitro, and secrete bioactive TIMP-2 freely from the microcapsules. 相似文献
14.
This paper presents ak-ε-k
p
multi-fluid model for simulating confined swirling gas-solid two phase jet comprised of particle-laden flow from a center
tube and a swirling air stream entering the test section from the coaxial annular. A series of numerical simulations of the
two-phase flow of 30 μm, 45 μm, 60 μm diameter particles respectively yielded results fitting well with published experimental
data.
Project is supported by Zheijiana Provincial Natural Science Foundation (No. 598017) 相似文献
15.
In H.264, computational complexity and memory access of deblocking filters are variable, dependent on video contents. This paper proposes a VLSI architecture of deblocking filters with adaptive dynamic power, which avoids redundant computations and memory accesses by precluding the blocks that can be skipped. The vertical and horizontal edges are simultaneously processed in an advanced scan order to speed up the decoder. As a result, dynamic power of the proposed architecture can be reduced adaptively （up to about 89%） for different videos, and the off-chip memory access is improved when compared to previous designs. Moreover, the processing capability of the proposed architecture is in particular appropriate for real-time deblocking of high-definition television （HDTV, 1920× 1080 pixels/frame, 60 frames/s video signals） video operation at 62 MHz. Using the proposed architecture, power can be reduced by up to about 89% and processing time by from 25% to 81% compared with previous designs. 相似文献
16.
This paper looks into the case of a school in Macao nominated as the first (and so far the only) China-Canada-United States
English Immersion (CCUEI) centre in the Macao Special Administrative Region (Macao SAR) China for the experimentation and
application of English immersion instruction (EI) in the K1-3 and Primary 1–2 classes. Drawing on Krashen’s Input Hypothesis
(1982) and Cummins’ (2000) framework of instruction for language learning and academic achievement in the formal school context,
the authors report their observations by analyzing the data collected from school teachers and participation in classes and
by reflecting on their experiences, and suggest improvement that can be made to teachers’ linguistic and communicative competence,
in terms of quantity and quality of comprehensible input and expected output, and thus the sustainability of English immersion
classrooms in a Chinese context. 相似文献
17.
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call EDRS for details. Expedited delivery is available; call EDRS for details. Payment including shipping must be included
with each order.All documents ordered from the EDRS must be identified by ED number. 相似文献
18.
A high speed column-parallel CDS/ADC circuit with nonlinearity compensation is proposed in this paper.The correlated double sampling (CDS) and analog-to-digital converter (ADC) functions are integrated in a threephase column-parallel circuit based on two floating gate inverters and switched-capacitor network.The conversion rate of traditional single-slope ADC is speeded up by dividing quantization to coarse step and fine step.A storage capacitor is used to store the result of coarse step and locate the section of ramp signal of fine step,which can reduce the clock step from 2 n to 2 (n/2+1).The floating gate inverters are implemented to reduce the power consumption.Its induced nonlinear offset is cancelled by introducing a compensation module to the input of inverter,which can equalize the coupling path in three phases of the proposed circuit.This circuit is designed and simulated for CMOS image sensor with 640×480 pixel array using Chartered 0.18μm process.Simulation results indicate that the resolution can reach 10-bit and the maximum frame rate can reach 200 frames/s with a main clock of 10MHz.The power consumption of this circuit is less than 36.5μW with a 3.3V power supply.The proposed CDS/ADC circuit is suitable for high resolution and high speed image sensors. 相似文献
19.
CUI Qiang HAN Yan DONG Shu-rong LIOU Juin-jie 《浙江大学学报(A卷英文版)》2007,8(12):1879-1883
A novel polysilicon-assisted silicon-controlled rectifier (SCR) is presented and analyzed in this paper, which is fabricated in HHNEC's 0.18 μm EEPROM process. The polysilicon-assisted SCRs take advantage of polysilicon layer to help bypass electro-static discharge (ESD) current without occupying extra layout area. TLP current-voltage (I-V) measurement results show that given the same layout areas, robustness performance of polysilicon-assisted SCRs can be improved to 3 times of con- ventional MLSCR's. Moreover, one-finger such polysilicon-assisted SCRs, which occupy only 947 μm2 layout area, can undergo 7-kV HBM ESD stress. Results further demonstrate that the S-type I-V characteristics of polysilicon-assisted SCRs are adjustable to different operating conditions by changing the device dimensions. Compared with traditional SCRs, this new SCR can bypass more ESD currents and consumes smaller IC area. 相似文献
20.
Lu Y Du SY Chen XL Wu Q Song X Xu B Zhai YS 《Journal of Zhejiang University. Science. B》2011,12(2):143-148
Both geniposide (Ge) and natural borneol (NB) are bioactive substances derived from traditional Chinese herbs. The effect
of NB on the pharmacokinetics of Ge in rat via intranasal administration was investigated. The concentrations of Ge in plasma
were determined by reversed-phase high-performance liquid chromatography (HPLC) after intranasal administration of Ge (4 mg/kg)
alone and combined with different doses (0.08, 0.8, and 8 mg/kg) of NB. The intravenous administration was given as a reference
(4 mg/kg of Ge and 8 mg/kg of NB). Compared with the intravenous administration, the absolute bioavailability of Ge was 76.14%
through intranasal administration combined with NB. Compared with the intranasal administration of Ge alone, Ge could be absorbed
rapidly in the nasal cavity combined with NB; the peak time of Ge in the plasma became shorter (3–5 min vs. 40 min); the peak
concentration became higher (1.32–4.25 μg/ml vs. 0.67 μg/ml); and, the relative bioavailability of Ge combined with NB was
90.3%–237.8%. The enhancing effect was attenuated as the dose of NB decreased. The results indicated that NB can accelerate
the absorption of Ge dose-dependently in the nasal cavity. 相似文献