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141.
In the post-weld heat treatment process, the reheat cracking which might occur in the weldments of low-alloy steels has been a serious problem. So, it is considered to be important to predict the possibility of occurrence of reheat cracking in these steels. It is however recognized as a time-consuming procedure to evaluate quantitatively the susceptibility to this type of cracking. In the present study, a new quantitative evaluation method of reheat cracking susceptibility by in situ observation and measurement using a laser confocal microscope has been proposed. Through this new method, the reheat cracking susceptibility of any kind of steels can be evaluated with the same standard. Moreover, because the position of the initial crack can be focused and the critical ductility to initiate the crack is measured by in situ observation, the reheat cracking susceptibility can be evaluated using only one specimen. So the newly developed method can provide efficient quantitative assessment of the reheat cracking sensitivity with high accuracy. 相似文献
142.
This paper undertakes a time series analysis of the Japanese divorce rate using annual data over the period 1964–2006. One of the key innovations of the paper is to use court decisions on divorce disputes to construct an index that seeks to measure how the probability of success in a divorce suit has changed over time. The computed index suggests that if it is the culpable party lodging the divorce suit, the probability of the suit being successful has clearly increased over time. The probability of winning a divorce suit appears to be an important factor in explaining the long-run rise in the Japanese divorce rate. The divorce rate also appears to be counter-cyclical. 相似文献
143.
Field-emission images of clean Cu and Au emitters show a peculiar halo-like ring centered at the [1 1 1] pole. Typical diameter and width of the ring are approximately 10 nm and approximately 2 nm, respectively. Since we found no geometrical features around the [1 1 1] pole that gives rise to such a ring pattern, we interpreted the ring pattern as representing enhanced emission from an annular terrace that resonantly confines surface electrons. A simple analysis shows that the observed ring pattern appears at a terrace whose width nearly matches the confinement condition. 相似文献
144.
145.
Calcium Concentration Dependence of the Intergranular Film Thickness in Silicon Nitride 总被引:1,自引:0,他引:1
Isao Tanaka Hans-Joachim Kleebe Michael K. Cinibulk John Bruley David R. Clarke Manfred Ruhle 《Journal of the American Ceramic Society》1994,77(4):911-914
High-resolution electron microscopy and nano-beam analytical electron microscopy have been used to characterize both the intergranular silicate film thickness and its local composition in a series of high-purity Si3 N4 ceramics doped with 0–450 at. ppm Ca. Calcium was detected at both two-grain junctions and triple junctions, even in the 80-ppm-Ca-doped specimen. The thickness of the intergranular film at two-grain junctions was found to depend sensitively on Ca content. In undoped material, the thickness was 1.0 ± 0.1 nm. With increasing Ca content, the thickness decreased in the dilute region (80 ppm Ca), but then increased. The variation in film thickness can be qualitatively understood in terms of the balance of three long-range forces acting normal to the film, namely the van der Waals dispersion force, a structural "steric" force, and an electrical-double-layer force. By comparing the measured thicknesses to those predicted, estimates for the structural correlation length and the inverse Debye length can be made. These estimates have values of ∼ 0.22 nm and approximately 0.3–0.5 nm, respectively, for the calcia-free and 80 ppm calcia materials. 相似文献
146.
The d.c. conductivity (σ) of V2O5-SnO-TeO2 glasses prepared by the press-quenching method was studied at temperatures from room temperature (RT) to 473 K, and the effect
of annealing on σ was investigated. The conductivity of 50V2O5·20SnO·30TeO2 glass was determined to be 3.98×10−4 Scm−1 at 473 K and was unchanged for annealing (6–48 h) at 493 K, lower than Tg = 501 K, while its density increased with annealing time. These glasses were found to be n-type semiconductors, and the conduction
was confirmed to be due to adiabatic small polaron hopping for V2O5 ≧ 50 mol%, and non-adiabatic for V2O5 < 50 mol%. The activation energy for conduction, W, decreased with annealing time. Variations in oxygen molar volume of the glasses with annealing time inferred a change in
glass structure, from loosely to closely packed, resulting in a decrease in vanadium ion spacing with annealing. This caused
an increase in the polaron band width, producing a decrease in polaron hopping energy and W. The effect of annealing time on the density of 50V2O5·20SnO·30TeO2 glass was explained adequately by Winter's formula. 相似文献
147.
K Ikeda R Nagai T Sakamoto H Sano T Araki N Sakata H Nakayama M Yoshida S Ueda S Horiuchi 《Canadian Metallurgical Quarterly》1998,215(1-2):95-104
An extractionless method for determining aflatoxin M1 (AFM1), a major metabolite of aflatoxin B1 (AFB1), in human urine was developed. The biological fluid is injected directly into the chromatographic system after simple dilution and centrifugation. A pre-column, packed with a cation-exchange phase and coupled on-line to a column-switching liquid chromatography (LC) system, is used for sample pre-treatment and concentration. The analytes are non-selectively desorbed with the LC eluent and cleaned by means of a column-switching procedure. Pre-treatment and analysis were performed within 40 min. Average AFMI recovery reached 97% in the 10-100 ng/l range of urine. The detection limit of AFM1 in urine and milk was 2.5 ng/l for 1 ml of injected sample. A comparison with an immunoaffinity column clean-up and LC method was performed. The method was applied to determine AFM1 in the urine of AFB1 gavaged rats, and in the urine of both potentially exposed and supposedly unexposed workers. The method was also extended to milk. 相似文献
148.
Grating-assisted vertical directional couplers can be combined with evanescently coupled absorption layers to realize integrated wavelength-selective photodetectors. The multimode structure of a photodetector including layered waveguides is studied, and mode transfer from the lossless filter section to the absorptive detector section is analyzed. By optimizing the device structure, the background absorption of unselected wavelengths can be suppressed, and, as a result, high crosstalk attenuation can be obtained. The filter bandwidth can be designed to cover a wide range from on the order of 10 nm down to the order of 0.5 nm with a device length that is shorter than 2 mm, which makes it suitable for various types of wavelength-division-multiplexing systems 相似文献
149.
Isao Sakaguchi Hisayoshi Yurimoto Shigeho Sueno 《Journal of the American Ceramic Society》1992,75(3):712-715
The lattice and dislocation diffusion coefficients for Ca2+ in single-crystal MgO have been determined in the temperature range 1743 to 1293 K from the diffusion penetration determined using secondary ion mass spectrometry. The dislocation diffusion coefficients were 4 to 5 orders of magnitude larger than the lattice diffusion coefficients in the same temperature range. The activation energy of Ca2+ lattice diffusion was comparable to that of ionic conductivity. The diffusion mechanism of Ca2+ is related to Mg vacancies. 相似文献
150.
Osamu Hanaizumi Yong-Gi Lee Isao Takahashi Tomohiko Nakajo Jun-Ichi Murota Shojiro Kawakami 《Optical Fiber Technology》1995,1(4)
A laminated polarization splitter for the wavelength region longer than 1.3 μm is fabricated for the first time. It is composed of a-SiC:H/SiO2 alternative multilayers prepared by plasma-enhanced chemical vapor deposition. Splitting behavior is also verified experimentally. It has low absorption loss even for the wavelength region around λ = 1.3 μm because the band-gap energy of a-Sic is larger than that of a-Si. The measured splitting angle is 13.8°, which is 2.4 times larger than the 5.7° splitting angle of rutile. The absorption loss of the multilayer is reduced to 1 × 10-3 dB/μm at λ = 1.3 μm. The magnitude of the residual stress is 9.45 × 108 dyn/cm2, which is about one-third of that prepared by the rf bias sputtering equipment which is used for another project of our group. The deposition rate of SiO2, is increased to 135 nm/min, which is 27 times larger than that prepared by the sputtering equipment. 相似文献