Stress intensity factor analysis of an interface crack between dissimilar anisotropic materials under thermal stress using the finite element analysis

New numerical methods were presented for stress intensity factor analyses of two-dimensional interfacial crack between dissimilar anisotropic materials subjected to thermal stress. The virtual crack extension method and the thermal M-integral method for a crack along the interface between two different materials were applied to the thermoelastic interfacial crack in anisotropic bimaterials. The moving least-squares approximation was used to calculate the value of the thermal M-integral. The thermal M-integral in conjunction with the moving least-squares approximation can calculate the stress intensity factors from only nodal displacements obtained by the finite element analysis. The stress intensity factors analyses of double edge cracks in jointed dissimilar isotropic semi-infinite plates subjected to thermal load were demonstrated. Excellent agreement was achieved between the numerical results obtained by the present methods and the exact solution. In addition, the stress intensity factors of double edge cracks in jointed dissimilar anisotropic semi-infinite plates subjected to thermal loads were analyzed. Their results appear reasonable.     

Crosslinking of polypropylene glycol with divalent metal salts of mono(hydroxyethyl) phthalate,anhydride, and bisepoxide

Crosslinking of polypropylene glycol with divalent metal salts of mono(hydroxyethyl) phthalate, anhydride, and bisepoxide is investigated. The anhydride and bisepoxide were hexahydrophthalic anhydride and bisphenol A diglycidyl ether. The metal carboxylate groups catalyzed the crosslinking reactions. The Mg carboxylate group showed higher catalytic activities than the Ca carboxylate group. The rubbers containing Mg showed much better physical properties than those containing Ca, due to higher interionic attraction of Mg⁺⁺ and better homogeneity. In addition, tensile strength of the cured rubbers at about the same soft block contents depended largely upon that of the hard block. Resistances to water and chemical attack, stress–relaxation, and thermal behavior are also discussed.     

Prototype abstraction and distinctive feature learning: An application to learning Chinese characters.

Chinese characters with related meanings often have a common symbol included among their components. In an exemplar-prototype and distinctive feature classification system, the multiple-component characters (the exemplars) can be said to have a common component (the prototype) distinctive to the shared concept. A study was conducted with 60 undergraduates who were administered recognition tests with new and old exemplars and prototypes. Results show that the traditional language learning technique of paired-associate training with exemplars of Chinese characters and specific English translations led to the poorest performance of the 3 methods tested. Learning either the English concept for Chinese exemplars (exemplar-category training) or the English concept for only the distinctive feature (prototype training) produced greatly superior performance. Instructions regarding the nature of Chinese characters had no effect on performance. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultra-thin GaxIn1−xAs/InP (0≤x≤0.47) layer growth by chemical beam epitaxy

Ga_xIn_1?xAs/InP (0≤x≤0.47) lattice-matched and compressively strained quantum wells were grown by all gas source chemical beam epitaxy (CBE). Their optical properties were investigated by photoluminescence (PL) and optical absorption measurements. The thinnest Ga_xIn_1?xAs layer was 6Å-thick (2 monolayers) for Ga_0.47In_0.53As and 3Å-thick (1 monolayer) for InAs. In PL measurements, we found that for strained materials (x<0.47) luminescence intensity dropped with decreasing barrier thickness. Optical absorption properties were measured at room temperature, and excitonic absorption peaks were clearly observed. The wavelengths of excitonic peaks were in good agreement with a theoretical estimation obtained by using an effective mass approximation including heavy and light hole energy splitting at the γ point.     

H2S sensing property of porous SnO2 sputtered films coated with various doping films

Pure SnO₂ films and Ag-, Cu-, Pt-, and Pd-doped SnO₂ films were investigated for H₂S sensing properties. SnO₂ films were deposited by DC magnetron sputtering at various substrate temperatures and discharge gas pressures. As the discharge gas pressure increased and the substrate temperature decreased, the film became porous. Doping with Cu or Ag film improved the sensitivity, and the highest sensitivity was obtained in the porous SnO₂ film coated with an Ag film 16 nm thick. According to the X-ray diffraction (XRD) pattern, Ag deposited on SnO₂ film transformed to Ag₂S upon exposure to H₂S. When the Ag-doped film sensor was operated at a low temperature, the sensitivity was extremely high, but the recovery was insufficient. By increasing the operation temperature, the recovery was improved but the sensitivity decreased.     

Development of nickel/metal-hydride batteries for EVs and HEVs

This paper is to introduce the nickel/metal-hydride (Ni/MH) batteries for electric vehicles (EVs) and hybrid electric vehicles (HEVs) developed and mass-produced by our company. EV-95 for EVs enables a vehicle to drive approximately 200 km per charge. As the specific power is extremely high, more than 200 W/kg at 80% depth of discharge (DOD), the acceleration performance is equivalent to that of gasoline fuel automobiles. The life characteristic is also superior. This battery gives the satisfactory result of more than 1000 cycles in bench tests and approximately 4-year on-board driving. EV-28 developed for small EVs comprises of a compact and light battery module with high specific power of 300 W/kg at 80% DOD by introducing a new technology for internal cell connection. Meanwhile, our cylindrical battery for the HEV was adopted into the first generation Toyota Prius in 1997 which is the world’s first mass-product HEV, and has a high specific power of 600 W/kg. Its life characteristic was found to be equivalent to more than 100,000 km driving. Furthermore, a new prismatic module in which six cells are connected internally was used for the second generation Prius in 2000. The prismatic battery comprises of a compact and light battery pack with a high specific power of 1000 W/kg, which is approximately 1.7 times that of conventional cylindrical batteries, as a consequence of the development of a new internal cell connection and a new current collection structure.     

Parallelizing fuzzy rule generation using GPGPU

This article proposes a method to parallelize the process of generating fuzzy if-then rules for pattern classification problems in order to reduce the computational time. The proposed method makes use of general purpose computation on graphics processing units (GPGPUs)’ parallel implementation with compute unified device architecture (CUDA), a development environment. CUDA contains a library to perform matrix operations in parallel. In the proposed method, published source codes of matrix multiplication are modified so that the membership values of given training patterns with antecedent fuzzy sets are calculated. In a series of computational experiments, it is shown that the computational time is reduced for those problems that require high computational effort.     

Control of nonstoichiometric defects in manganese oxides by self-propagating high-temperature synthesis

Nonstoichiometric compounds of Mn_1−δO were self-propagating high-temperature synthesized by ignition of thoroughly mixed powders of Mn, NaClO₄, and MnO without additional external heating. The mixing ratio was systematically varied to control δ. Single phase Mn_1−δO products containing nonstoichiometric defects were obtained for 0 < δ ≤ 0.025. With increase in δ, Mn₃O₄ content of the products is increased. Double phases of Mn_1−δO and Mn₃O₄ were obtained at 0.025 < δ ≤ 0.150. The lattice parameter, a, of the single phase Mn_1−δO was well explained by the linear equation: a = −0.0667δ + 4.448.     

Detailed analyses of key phenomena in core disruptive accidents of sodium-cooled fast reactors by the COMPASS code

A five-year research project has been initiated in 2005 to develop a code based on the MPS (Moving Particle Semi-implicit) method for detailed analysis of key phenomena in core disruptive accidents (CDAs) of sodium-cooled fast reactors (SFRs). The code is named COMPASS (Computer Code with Moving Particle Semi-implicit for Reactor Safety Analysis). The key phenomena include (1) fuel pin failure and disruption, (2) molten pool boiling, (3) melt freezing and blockage formation, (4) duct wall failure, (5) low-energy disruptive core motion, (6) debris-bed coolability, and (7) metal–fuel pin failure. Validation study of COMPASS is progressing for these key phenomena. In this paper, recent COMPASS results of detailed analyses for the several key phenomena are summarized. Simulations of GEYSER and THEFIS experiments were performed for dispersion and freezing behaviors of molten materials in narrow flow channels. In particular, the latter experiment using melt–solid mixture is also related to fundamental behavior of low energy disruptive core. CABRI-TPA2 experiment was simulated for boiling behavior of molten core pool. Expected mechanism of heat transfer between molten fuel and steel mixture was reproduced by the simulation. Analyses of structural dynamics using elastoplastic mechanics and fracture criteria were performed for SCARABEE BE+3 and CABRI E7 experiments. These two analyses are especially focused on thermal and mechanical failure of steel duct wall and fuel pin, respectively. The present results demonstrate COMPASS will be useful to understand and clarify the key phenomena of CDAs in SFRs in details.