Electronic states and cation distributions of MgAl2O4 and Mg0.4Al2.4O4 microwave dielectric ceramics

The electronic state and microwave dielectric properties of MgAl₂O₄ prepared using solid-state (MA-S) and molten salt (MA-M) methods and those of Mg_0.4Al_2.4O₄ (M04A24) were investigated. The λ values, which correspond to the fraction of Al³⁺ cations in tetrahedral sites, for MA-S, MA-M, and M04A24 were 0.23, 0.41, and 0.60, respectively. In molecular orbital calculations, a larger overlap was observed between Al-3s or Al-3p in tetrahedral sites and O-2p orbitals for M04A24, and the bond order for AlO at tetrahedral sites of M04A24 (0.241) was higher than those for MA-S (0.178) and MA-M (0.205). The dielectric constant, ε_r, for M04A24 (7.6) was lower than those for MA-S and MA-M (both 7.9), and the highest quality factor, Q·f, was obtained for M04A24 (235, 800 GHz). It was found that the covalency of the AlO bonds in the MO₄ tetrahedra is closely related to the Q?f values of the present ceramics.     

X-ray computed tomography used to measure fiber orientation in CFRP laminates

This paper explains a new method to measure the fiber orientation in carbon fiber reinforced plastics (CFRP) laminates from X-ray CT images. In the method, the fiber orientation is analyzed by the application of digital image correlation (DIC) method to the acquired tomographic images. Using DIC, the brightness pattern, which results from the radiodensity difference between fiber and resin, is compared between two different planes in the thickness direction. Then, the three-dimensional displacement of the brightness pattern, which indicates the fiber orientation, can be measured. This study applied the proposed method to a quasi-isotropic CFRP laminate. After X-ray CT imaging, the sample was sectioned and polished. The fiber orientation was then measured experimentally using microscopy. The fiber orientation calculated using the proposed method agrees very well with the experimentally measured one. After demonstrating the validity of the proposed method, we applied it to a plain woven CFRP laminate. Results revealed that an invalid fiber orientation might be calculated for fibers parallel to the plane of the CT image, or for the fiber orientation of the pattern around the outer edge of CT images.     

High-speed micromachining characteristics for the NiTi shape memory alloys

The present study includes three parts—design and development of rotary liquid nitrogen applicator, investigation of machining performance under cryogenic application by using the developed applicator, and lastly comparison of the performances with dry and flood cutting. The surface milling of hardened EN 24 steel was performed at different speed-feed combinations corresponding to full factorial design plan (48 exp. runs). The effects of cutting speed, feed rate, and cutting conditions were investigated in respect of surface roughness, cutting force, and tool flank wear. The results of this study revealed the supremacy of cryogenic cooling in respect of all investigated quality characteristics. Lack of cooling and lubrication in dry cutting, and inadequate cooling and lubrication of flood cutting resulted in worse performance. On contrary, the double action cooling effect of cryogenic produces a superior performance, when passes through internal channel, firstly—due to an increased heat transfer rate caused by the primary and secondary flow within cutter, and secondly—because of the creation of a swirl flow at the outlet of the channel but within work surface.     

Amidoxime resins based on poly(acrylonitrile-co-vinylidene chloride-co-divinylbenzene) and their behavior in uptake of uranium from sea water

Amidoxime resins were derived from poly(acrylonitrile-co-vinylidene chloride-co-divinyl-benzene) beads, which were prepared by suspension polymerization of the ternary monomeric mixtures in the presence of 4-methyl-2-pentanone (MIBK) or 1,2-dichloroethane (DCE) as the diluent (porogen), in order to clarify the effect of copolymerized vinylidene chloride on properties of the resulting amidoxime resins. Pore structure analyses of the copolymers as well as of their amidoximated derivatives clarified that MIBK yields larger pores than does DCE and then the latter gives larger specific surface areas than does the former. On the other hand, chemical properties of the amidoximated resins, such as anionexchange capacities and uranyl ion uptake, were not eseentially affected by the diluent species, indicating that both MIBK and DCE as the porogen lead to the amidoxime resins with almost the same ability in recovery of uranium from sea water. The uranium recovery decreased with increase in the vinylidene chloride content, but the decrease in the recovery was minor up to the 10 mol % of vinylidene chloride. It was also clarified that the uranium recovery by the amidoxime resins containing vinylidene chloride is greatly enhanced by the alkali treatment. © 1994 John Wiley & Sons, Inc.     

A Support System for Fuzzy Optimum Aseismic Structural Design of Reinforced Concrete Buildings Using Graphical Representation

Abstract: In this paper, a support system of optimum aseismic design is proposed on the basis of fuzzy set theory and a graphical representation method. In optimum aseismic design of buildings, it is necessary to take account of subjective evaluation of users. In this system, a hierarchical model is employed to idealize and model the decision process of optimum aseismic design. By applying fuzzy set theory, this system can take account of subjective evaluation of users. The system is a prototype of an expert system for optimum aseismic design, and its knowledge is compiled interactively as numerical values by the fuzzy confluence rule and membership functions in fuzzy set theory in accordance with the hierarchical model given by users. Knowledge, which is necessary to perform the inference on optimum aseismic design, is acquired interactively. Optimization is performed by fuzzy multiobjective maximizing decision, and the maximum evaluation values of the top attribute can be found. Furthermore, distributions of the grade of membership value in maximizing the decision process are graphically represented, so the user can understand this process easily and intuitively. A case study is carried out for a reinforced concrete typical high school building in Kobe City.     

Deformation of antisymmetric laminate under centrifugal force and/or thermal load

A smart blade conception has been proposed by the authors. With stretching–twisting coupling effect, the blade is twisted by centrifugal load or ambient temperature change. In this paper, the blade, simplified as a cantilevered antisymmetric laminate, is investigated by classic plate theory. An analytical scheme based on Rayleigh–Ritz (RR) method is proposed to calculate plate's deformation behavior. RR's analytical results are compared with FEM's to check the present scheme's numerical accuracy. Influence of the fiber orientation angle is discussed and the angle at which the blade twists most is found. Further analysis focusing on plate's nonlinear behavior is performed. The nonlinearity, originated with large out-plane deflection, influences the plate in two aspects: large-strain and follower force. These aspects are discussed separately in the analysis, by introducing quadric terms into strain and virtual work expressions. It is shown that for the present model, nonlinear influence must be considered at 10,000 rpm rotation speed loading, but is negligible at temperature-load below 120 K.     

Theory of volume phase transition of slide-ring gels

Volume phase transition is a phenomenon in which gels drastically swell or shrink with an infinitesimal change in the external environment. This behavior is well explained by the Flory–Rehner–Tanaka theory. However, some assumption in the theory breaks down in a slide-ring gel composed of grand canonical chains in which the segment number between cross-linking junctions can change. The stress–strain behavior of the slide-ring gel is in a qualitative agreement with the free junction model, in which the segment number changes to maximize the entropy under the condition that the total sum of the segment number is constant. However, the model cannot work well to isotropic swelling of the slide-ring gel. To describe the volume phase transition of the slide-ring gel, we propose a new theory based on the free junction model with the effects of dangling strands, uncross-linked cyclic molecules (free rings), and high elongation. As a result, it turns out that the exchange of segments between effective and dangling strands leads to the suppression of the volume phase transition in the highly cross-linked gel and the promotion in the loosely cross-linked one. The suppression and promotion of the volume phase transition became more obvious as free rings decreased.     

Fast and robust training of a probabilistic latent semantic analysis model by the parallel learning and data segmentation

Probabilistic Latent Semantic Analysis （PLSA） is proven to be effective in the information retrieval and the speech recognition technique. In this paper, we modify the calculation procedure of estimation algorithm. It substantially reduces the memory requirements. And, parallelization approach enables making models in less time. Next, we examined data segmentation for PLSA adaptation. Most meetings have a number of topics. We divide the meeting automatically and fit PLSA models with them. The experiment showed recognition performance improvement.     

Determination of levulinic acid in soy sauce by liquid chromatography with mass spectrometric detection

A novel method using liquid chromatography coupled with mass spectrometry (LC–MS) was developed for the determination of levulinic acid (LV) in soy sauces to identify the addition of acid hydrolyzed vegetable protein (acid-HVP). One hundred percentage naturally brewed soy sauce (NBS) and enzymatic hydrolyzed vegetable protein (enzymatic HVP) did not contain LV (<0.01 mg/mL). There was apparent detection of LV in acid-HVP and blended soy sauce with acid-HVP (2.98–21.66 mg/mL). Gas chromatography (GC) and high performance liquid chromatography (HPLC) at 430 nm methods were also investigated. The results by GC gave similar data to those by LC–MS. In enzymatic HVP, LV was detected by HPLC at 430 nm, but it was confirmed that the detected component was not in fact LV by mass spectrometric identification of the isolated peak compound. We found that LV is under the detection limit in enzymatic HVP. This study showed that LV is below the detection limit in NBS and enzymatic HVP and is apparently detected in acid-HVP and blended soy sauces with acid-HVP. These results indicate that LV is a practical index of blend with acid-HVP and also corresponds with the JAS (Japanese Agricultural Standard) or CNS (Chinese National Standard) criteria in which the presence of LV in soy sauces indicates adulteration with acid-HVP. The LC–MS method is analytically optimal for the precise determination of LV, because peak misidentification may be practically eliminated.