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141.
Database systems are widely used in many fields. As the scale of database systems increases, more firms decide to deploy the database system in a distributed environment for the sake of data integrity fault tolerance. For guaranteeing the consistency of data, database management systems adopt isolation policies. This paper discusses probabilistic models for snapshot isolation of database management system. Snapshot isolation is an effective method to enhance the consistency of database system, although it degrades the system performance where the system has large network latency such as distributed database system. Also, under the failure-prone environment, a restart scheme is considered as one countermeasure. This paper proposes probabilistic models for the dynamics of snapshot isolation of database system and exhibits the optimization of system performance with respect to updating interval of snapshot isolation within the failure-prone environment from the analytical point of view. Numerical experiments are conducted to validate the effectiveness of analytical results by using real traffic data. 相似文献
142.
p-Styrenesulfonate derivatives having cycloaliphatic epoxide in a molecule, were synthesized. Oligomerization of the monomers and co-polymerization of the novel monomers with tert-butyl methacrylate were carried out. When the polymer films containing a photoacid generator (PAG) were irradiated, they became insoluble in solvents. The insoluble films became soluble in water on baking at 120-200 °C. The insolubilization and redissolution profiles were strongly affected by the structure of the monomer, irradiation and baking conditions, and a type of PAG used. The reaction mechanism was studied by TGA analysis and FT-IR spectroscopy. 相似文献
143.
Hirokazu Okamura Takeshi MoriKeiji Minagawa Seizo MasudaMasami Tanaka 《Polymer》2002,43(13):3825-3828
A novel thermosensitive polymer, poly(methyl 2-propionamidoacrylate) (PMPA), was prepared and the phase transition behavior in an aqueous solution was studied. PMPA have geminal substituents of propionamide and methoxy carbonyl in each monomer unit. It was found that PMPA shows the lower critical solution temperature (LCST) at 50.6 °C sharply. The LCST of PMPA was almost independent of the polymer concentration above 40 g/l, while, below 40 g/l, it decreased with the increasing polymer concentration. The effect of salt addition (NaCl, NaBr, and Na2SO4) on the LCST was also studied. The LCST of PMPA linearly decreased with the increasing concentration of each salt. The salting-out effect of these salts was in line with the Hofmeister series: Na2SO4>NaCl>NaBr. 相似文献
144.
Yoshie Kitayama Masahiro Muraoka Megumi Takahashi Tatsuya Kodama Eriko Takahashi Mutsuo Okamura 《Journal of the American Oil Chemists' Society》1997,74(5):525-529
Catalytic activity and selectivity for hydrogenation of linoleic acid (cis-9,cis-12 18:2) were studied on Pt, Pd, Ru, and Ir supported on Al2O3. Stearic acid (18:0) and 10 different octadecenoic isomers (18:1) in the products could be separated completely by using a new capillary column coated by isocyanopropyl trisilphenylene siloxane for gas-liquid chromatography. The monoenoic acid isomers and dienoic acid isomers in the products on the various catalysts showed different distributions. The catalysts exhibited nearly equal selectivity for stearic acid formation. The 12-position double bond in linoleic acid has higher reactivity than the 9-position double bond in catalytic hydrogenation on platinum-group metal catalysts. In addition to hydrogenation products of linoleic acid, geometrical and positional dienoic acid isomers (trans-9,trans-12; trans-8,cis-12; cis-9,trans-13; trans-9,cis-13; cis-9,trans-12 18:2), due to isomerization of linoleic acid during hydrogenation, were contained in the reaction products. Ru/Al2O3 exhibited the highest activity for isomerization of linoleic acid with the noble metal catalysts. Conjugated octadecadienoic acid isomers have been observed in products of the reaction on Pt/Al2O3, Ru/Al2O3, and Ir/Al2O3. Catalytic activities of noble metals for positional and geometric isomerization of linoleic acid during hydrogenation decreased in the sequence of Ru ≥ Pt > Ir » Pd. 相似文献
145.
Von Tiedemann M Fridberger A Ulfendahl M Tomo I Boutet de Monvel J De Monvel JB 《Microscopy research and technique》2006,69(1):10-20
Visualizing deep inside the tissue of a thick biological sample often poses severe constraints on image conditions. Standard restoration techniques (denoising and deconvolution) can then be very useful, allowing one to increase the signal-to-noise ratio and the resolution of the images. In this paper, we consider the problem of obtaining a good determination of the point-spread function (PSF) of a confocal microscope, a prerequisite for applying deconvolution to three-dimensional image stacks acquired with this system. Because of scattering and optical distortion induced by the sample, the PSF has to be acquired anew for each experiment. To tackle this problem, we used a screening approach to estimate the PSF adaptively and automatically from the images. Small PSF-like structures were detected in the images, and a theoretical PSF model reshaped to match the geometric characteristics of these structures. We used numerical experiments to quantify the sensitivity of our detection method, and we demonstrated its usefulness by deconvolving images of the hearing organ acquired in vitro and in vivo. 相似文献
146.
The electron beam ion source (EBIS) preinjector at Brookhaven National Laboratory (BNL) is a new heavy ion-preinjector for relativistic heavy ion collider (RHIC) and NASA Space Radiation Laboratory (NSRL). Laser ion source (LIS) is a primary ion source provider for the BNL-EBIS. LIS with solenoid at the plasma drift section can realize the low peak current (~100 μA) with high charge (~10 nC) which is the BNL-EBIS requirement. The gap between two solenoids does not cause serious plasma current decay, which helps us to make up the BNL-EBIS beamline. 相似文献
147.
制革废水及革制品废料所含铬引起的环境与卫生污染是一个严重的问题。加脂可以影响皮革的性能,其目的就是赋予成革以柔软性,良好的手感和一定的强度,缺点是加脂使革重量增加,抗水性减弱,有时还会引起增塑剂和染料的迁移。为解决此问题,本论文采用不使用铬和加脂剂的方法来处理皮革,并对以这种方法所加工皮革的性能进行研究。结果如下:(1)对于剖层,削匀或修边等废料,因其不含铬而可加以利用或焚烧处理;(2)所制成革具有防水性,性能优于防水性的革;(3)成革视密度下降;(4)染色革的耐光性明显优于荆树皮~铝鞣革,后者系典型的非铬鞣革之一,此法还可有效防止白色革泛黄。 相似文献
148.
M Tomura S Maruo J Mu XY Zhou HJ Ahn T Hamaoka H Okamura K Nakanishi S Clark M Kurimoto H Fujiwara 《Canadian Metallurgical Quarterly》1998,160(8):3759-3765
IL-12 and IL-18 have the capacity to stimulate IFN-gamma production by T cells. Using a T cell clone, we reported that IL-18 responsiveness is generated only after exposure to IL-12. Here, we investigated the induction of IL-18 responsiveness in resting CD8+, CD4+, and CD4-CD8- T cells. Resting T cells respond to neither IL-12 nor IL-18. After stimulation with anti-CD3 plus anti-CD28 mAbs, CD8+, CD4+, and CD4-CD8- T cells expressed IL-12R, but not IL-18R, and produced IFN-gamma in response to IL-12. Cultures of T cells with anti-CD3/anti-CD28 in the presence of rIL-12 induced IL-18R expression and IL-18-stimulated IFN-gamma production, which reached higher levels than that induced by IL-12 stimulation. However, there was a substantial difference in the expression of IL-18R and IL-18-stimulated IFN-gamma production among T cell subsets. CD4+ cells expressed marginal levels of IL-18R and produced small amounts of IFN-gamma, whereas CD8+ cells expressed higher levels of IL-18R and produced more IFN-gamma than CD4+ cells. Moreover, CD4-CD8- cells expressed levels of IL-18R comparable to those for CD8+ cells but produced IFN-gamma one order higher than did CD8+ cells. These results indicate that the induction of IL-18R and IL-18 responsiveness by IL-12 represents a mechanism underlying enhanced IFN-gamma production by resting T cells, but the operation of this mechanism differs depending on the T cell subset stimulated. 相似文献
149.
150.
Atsuo Honda Koichiro Tezuka Tomohito Okamura Kaoru Kawamoto Shoji Shimizu Kohei Harada Takahito Tanabe Tatsuya Shirakawa Tomohiro Takahashi 《Electrical Engineering in Japan》2019,206(4):22-35
Osaka Gas Co., Ltd., jointly with NTT DATA Mathematical Systems Inc., has developed unit‐commitment model for optimizing dispatch of power generation units. Main purpose of this development is to simulate the future world of electric power system in accordance with national energy policy aiming to introduce large amount of renewable energy as well as vitalized cross‐border power exchange via PX market to enhance economically‐efficient power system operation. The model incorporates not only constraints of supply‐demand balance but also constraints of operating reserves, regulation reserves, maximum CO2‐emissions, etc. 相似文献