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91.
Summary Optimum preventive maintenance policies for a two-unit standby redundant system are reviewed. Under the assumptions that all distributions are arbitrary, the first-passage time distributions, the transition probabilities, and the expected numbers of visits to a certain state are derived. Using the probabilistic quantities above, we discuss the optimum preventive maintenance policies maximizing or minimizing some criteria. We show that under suitable conditions there exist the optimum preventive maintenance policies which are given by the unique solutions of the equations. This paper concludes with numerical examples of such optimum preventive maintenance policies.
Zusammenfassung In diesem Aufsatz werden optimale Strategien zur vorbeugenden Instandhaltung für ein System mit zwei Maschinen besprochen, wobei eine Maschine die Ersatzmaschine darstellt. Unter der Annahme willkürlicher Verteilungen werden die Verteilung der Zeit für den ersten Durchgang, die übergangswahrscheinlichkeiten und die erwartete Zahl des Erreichens eines bestimmten Zustandes abgeleitet. Anhand der oben erwähnten Wahrscheinlichkeitswerte werden optimale Strategien zur vorbeugenden Instandhaltung besprochen, die bestimmte Kriterien maximieren oder minimieren. Es wird gezeigt, daß bei entsprechenden Bedingungen optimale Strategien zur vorbeugenden Instandhaltung existieren, die man als eindeutige Lösung eines Gleichungssystems erhält. Am Ende des Aufsatzes werden numerische Beispiele für optimale Strategien gegeben.相似文献
92.
Hasegawa T Fujisawa T Numata M Umeda M Matsumoto T Kimura T Okumura S Sakurai K Shinkai S 《Chemical communications (Cambridge, England)》2004,(19):2150-2151
Single-walled carbon nanotubes can be entrapped within a helical superstructure composed of schizophyllan bearing lactoside-appendages to show an excellent water-solubility as well as a specific lectin-affinity. 相似文献
93.
94.
95.
H. Watanabe Kunihiro Osaki Mutsuo Matsumoto Dobrin P. Bossev Cathy E. McNamee Masaru Nakahara Ming-Long Yao 《Rheologica Acta》1998,37(5):470-485
Nonlinear rheological features were investigated for an aqueous solution of tetraethylammonium perfluorooctyl sulfonate (C8F17SO3
–N+(C2H5)4; abbreviated as FOSTEA). In the solution (c=0.045 mol/l; 28.3 g/l), spherical micelles of FOSTEA were connected with each other to form threads of pearl-necklace shape.
These threads were further organized into a transient network to exhibit linear relaxation characteristic of living polymers,
single-mode terminal relaxation widely separated from faster relaxation processes. Nonlinear relaxation experiments against
large step-strains γ(≤8) revealed that the terminal relaxation mode had a γ-insensitive relaxation time but its relaxation
intensity exhibited significant damping (much stronger than that for entangled polymers). In contrast, the relaxation time
and intensity for the fast relaxation modes first increased and then decreased with increasing γ. Under shear flow, the FOSTEA
threads exhibited strong thinning of the viscosity. These nonlinear features of the FOSTEA threads were compared with those
of other threadlike micelles, analyzed on the basis of an empirically introduced constitutive equation, and discussed in relation
to strain/low-induced scission of the living threads.
Received: 20 February 1998 Accepted: 30 July 1998 相似文献
96.
Hideyuki Nakanishi Yuto Kawabata Shogo Tsujiai Hayato Tanaka Satoshi Teraji Gbor Holl Istvn Lagzi Tomohisa Norisuye Qui Tran‐Cong‐Miyata 《Angewandte Chemie (International ed. in English)》2020,59(31):13086-13092
The development of methods to pattern nanocrystals with different sizes and shapes remains a challenge. In this study, we demonstrate a unique class of bottom‐up approaches to assemble nanocrystals into patterns. Our approach for patterning nanocrystals focuses on the utilization and control of the chemical reaction of solvents surrounding nanocrystals. The photopolymerization of solvent molecules through a photomask creates time‐dependent concentration gradients of the solvents. Dispersed nanocrystals such as silver nanowires (AgNWs) migrate and are gradually organized and integrated into the polymerizing films based on the concentration gradients. The AgNW‐embedded film properties are determined by the organized AgNW structures and include light transmission and electrical conductivity. Overall, the demonstrated method is very simple, widely applicable to various nanocrystals and solvents, and can thus contribute to the development of a new class of nanocrystal patterning methods. 相似文献
97.
Akira Yamaguchi Tatsuya Uchida Kimihisa Nochi Tomohisa Yamashita Norio Teramae 《Analytical sciences》2004,20(11):1523-1527
Interfacial tensiometry and second harmonic generation (SHG) spectroscopy were applied to examine the adsorption behavior of lauric acid (LA) at a heptane/water interface. From interfacial tensiometry measurements, the adsorption kinetics of LA was revealed to be diffusion-controlled, and the adsorption constant of LA was estimated to be 9.6 x 10(4) M(-1). The adsorption isotherms obtained by SHG measurements were analyzed by taking account of both the molecular orientation of LA at the interface and a surface electric field generated by the adsorbed LA layer. It was confirmed that the carboxylic groups of adsorbed LA molecules were well ordered at the heptane/water interface and the orientation of the carboxylate group was invariant during the adsorption process. 相似文献
98.
One of the most important issues for a development manager may be how to predict the reliability of a software system at an arbitrary testing time. In this paper, using the software failure-occurrence time data, we discuss a method of software reliability prediction based on software reliability growth models described by an NHPP (nonhomogeneous Poisson process). From the applied software reliability growth models, the conditional probability distribution of the time between software failures is derived, and its mean and median are obtained as reliability prediction measures. Finally, based on several numerical examples, we compare the performance between these measures from the view point of software reliability prediction in the testing phase. 相似文献
99.
Iwao Satake Masao Fukuda Tomohisa Ohta K
zaburo Nakamura Noboru Fujita Akira Yamauchi Hideo Kimizuka 《Journal of Polymer Science.Polymer Physics》1972,10(12):2343-2354
Counterion activity coefficients in solutions of dextran sulfate with and without added salts were determined potentiometrically by using a cation-exchange membrane and a sodium glass electrode. Dextran sulfate was shown to interact with monovalent cations in the order of preference: K+ > Cs+ > Na+ > Li+, whereas no specificity was found for bivalent cations. On the basis of light-scattering measurements, the expansion of the dextran sulfate polyion in solutions of alkali metal salts was found to fall in the same order as the counterion activity coefficients in salt-free solutions. It was also shown that the dextran sulfate polyion assumes a more extended conformation in magnesium chloride solution than in calcium chloride. These results were substantiated by measurements of solution viscosities. 相似文献
100.
Shigeyoshi Osaki Shinsaku Uemura Y
ichi Ishida 《Journal of Polymer Science.Polymer Physics》1971,9(4):585-594
Dielectric measurements on poly(vinylidene fluoride) at higher temperatures result in anomalously large values of ε′ and ε″ at lower frequencies. When a static field is applied, a drastic decrease of ε′ and ε″ occurs. The effects of a static field can be summarized as follows: (1) the field effect upon ε′and ε″ is more significant at lower frequencies; (2) with increasing field strength, the rate of decrease of ε′and ε″ with time becomes greater and the ultimate values are smaller; (3) when the field is removed, ε′and ε″ recover but the ultimate recovery is incomplete; (4) the field effect depends strongly on temperature. Such behavior seems to be attributable to the displacement of ionic impurities and to their electrolysis. These results provided a method to remove the contribution of ionic impurities to ε′and ε″ and to measure the relaxation process due only to dipoles of a polymer. The application of this method revealed the dielectric high temperature absorption which had been masked by the ionic conduction in poly(vinyl fluoride). 相似文献