Inspection policy for two-unit parallel redundant system

This paper deals with a single-server two-unit parallel redundant system with non-negligible inspection time. We shall assume that a failure of a unit or the system failure is detected by inspection only. We consider two inspection policies and under each inspection policy the stationary availability is derived by applying Piecewise Markov Process. Optimum inspection schedule is discussed to maximize the stationary availability of the system. A numerical example is presented.     

An inspection policy for one-unit system subject to revealed and unrevealed failures

This paper deals with a single-server one-unit system subject to both revealed and unrevealed failures. We shall assume that a revealed failure is detected as soon as it occures but an unrevealed failure is detected by an inspection only. Under an inspection policy, the Laplace transform of the pointwise availability of the system and the stationary availability of the system are derived by using the supplementary variable method. Further, we discuss the optimum inspection schedule maximizing the stationary availability. Finally, some numerical examples are presented.     

An Organic–Inorganic Hybrid Composite as a Coating Agent

An organic–inorganic hybrid composite for use as a coating agent was prepared by mixing linseed oil with hydrophobic octylsilyl titanium dioxide particles having an average diameter of 35 nm (OSI-TIO2-35) in volatile silicone. The weight ratio of linseed oil with OSI-TIO2-35 was varied from 2:8 to 8:2 and the mixture was spread on a glass plate by dragging an applicator across it. After storing in the oven at 60 °C for 2 days, the composite having the weight ratio of OSI-TIO2-35 with linseed oil at 8:2 exhibited very high water-repellent properties having a water contact angle of 148°. Variation of the water contact angle during storage at 60 °C was monitored. It decreased by 10° in the initial 8 h and then increased by 45° over the next 2 days. Composites containing silicone resin, TMSS BY11-018, instead of linseed oil were also prepared. The sample having a weight ratio of OSI-TIO2-35 with TMSS BY11-018 at 8:2 also exhibited very high water-repellent properties with a water contact angle of 152°. The highly hydrophobic surface thus prepared by the coating and drying of those organic-inorganic hybrid composites was easily transferred to highly hydrophilic surfaces by calcination at 500 °C for 3 h.     

Properties of commercial licorice extracts used as a food additive

Properties of eight commercial licorice extracts used as a food additive (sweetener, listed in the List of Existing Food Additives in the Japanese Food Sanitation Law) were surveyed. Residue on ignition ranged from 0.3 to 12.4%, and pH ranged from 4.1 to 6.8, amount of glycyrrhizin, which is the major component in licorice extract, ranged from 10.9 to 77.4%, sodium ranged from 0.1 to 1.2%, potassium ranged from 0.3 to 5.0%, and ammonium nitrogen ranged from 0.03 to 2.5%. These results indicated that various products were distributed on the market. Differences in the manufacturing process may contribute to the variations of product properties.     

Three-dimensional shift selectivity in reflection-type holographic disk memory with speckle shift recording

Three-dimensional shift selectivity of a reflection-type hologram with speckle shift recording is investigated experimentally and numerically. We build an experimental setup consisting of lenses with numerical apertures of 0.28 and an iron-doped LiNbO(3) with a thickness of 0.5 mm. The experimental results show that three-dimensional selectivity has a size of 0.97 microm x 0.97 microm x 8.8 microm in diffraction efficiency. We also develop a volume holographic memory simulator to evaluate the experimental results. The simulator can quantitatively evaluate bit error rate, signal-to-noise ratio, and diffraction efficiency. Numerical results are in good agreement with the experimental results. The experimental and numerical results indicate that three-dimensional shift multiplexing can increase the storage capacity.     

Iterative algorithm of phase determination in digital holography for real-time recording of real objects

We propose a numerical method to obtain complex amplitude distribution of a three-dimensional (3D) object from a digital hologram. The method consists of two processes. The first process is to measure simultaneously a hologram of the 3D object and an object intensity distribution by two image sensors. These intensity distributions give us the amplitude and absolute value of phase of the 3D object at the image sensor plane. The second process is the determination of phase distribution by a proposed iterative process based on the criterion that the reconstructed 3D object is in focus and its conjugate reconstruction is out of focus. Numerical and experimental results show the effectiveness of the proposed method.     

Effects of HAZ softening on the strength and elongation of resistance spot-welded joints in high-strength steel sheet in an in-plane tensile test

ABSTRACT

In this study, we investigated the effects of heat-affected zone (HAZ) softening on the strength and elongation of resistance spot-welded joints in high-strength steel sheet in an in-plane tensile test. The fracture in the softened HAZ had a little effect on the maximum stress of the resistance spot-welded specimen; however, the fracture elongation decreased. The nugget diameter and HAZ softened width had little effect on the fracture elongation of the resistance spot-welded specimen. Also, the fracture elongation decreased slightly with the decrease in the sheet thickness. The major factor affecting the fracture elongation was the HAZ hardness ratio (= Softened HAZ/Base metal × 100%). For the resistance spot-welded specimen with a thickness of 1.6 mm, when the HAZ hardness ratio decreased to less than 80%, the fracture position changed from the base metal to the softened HAZ and the fracture elongation decreased sharply. In addition, with a decrease in the hardness ratio, the fracture elongation decreased.     

Development of Adsorption Steam Generator without the Fossil Fuels Consumption

Reducing CO2 emissions and restraining dependence on nuclear power generation are serious concerns in the prevention of global warming since the Great East Japan Earthquake. To do so, it is necessary to use and expand natural renewable energy source such as solar energy and to promote energy conservation. However, in high-latitude regions, it is difficult to directly and effectively use solar power due to on insufficient amount of solar radiation. If steam can be generated from warm water at less than 373 K, it is possible to obtain steam by solar water heaters from weak solar radiation and industrial waste warm water without the consumption of any fossil fuels. In this study, the authors have been developing a system which generates steam over 423 K from warm water at less than 373 K using an adsorption heat pump with zeolite. Therefore, bench-scale equipment which generates steam continuously and the experimental results are mentioned.     

Enhanced piezoelectric properties of barium titanate–potassium niobate nano-structured ceramics by MPB engineering

Barium titanate (BaTiO₃, BT)–potassium niobate (KNbO₃, KN) (BT–KN) nanocomplex ceramics with various KN/BT molar ratios were prepared by the solvothermal method. From a transmittance electron microscopy (TEM) observation, it was confirmed that KN layer thickness of the BT–KN nanocomplex ceramics was controlled from 0 to 44 nm by controlling KN/BT molar ratios. Their dielectric constants were measured at room temperature and 1 MHz, and a maximum dielectric constant of around 400 was measured for the BT–KN nanocomplex ceramics with a KN thickness of 22 nm. TEM observation revealed that below KN thickness of 22 nm, BT/KN heteroepitaxial interface was assigned to the strained interface while over 22 nm, the interface was assigned to the relaxed one. These results suggested that the strained heteroepitaxial interface could be responsible for the enhanced dielectric constants.