Long-term observation of subcutaneous tissue reaction to synthetic auditory ossicle (Apaceram) in rats

The present study evaluates histological characteristics of the soft tissue response to long-term implantation of Apaceram discs composed of dense hydroxyapatite in rats. Discs were implanted into the subcutaneous tissue of 76 rats for six to 20 months. Decalcified histological sections stained with haematoxylin and eosin (H & E) and Mallory's azan were examined. Different cell types surrounding implants were counted. The greatest proportion of macrophages was found at six months (13.5 per cent). This proportion gradually decreased to four per cent at 20 months. Small numbers of lymphocytes and foreign body giant cells were observed in every group, but neither neutrophils nor osteogenesis were observed in any specimens. Results of the present study and previous related studies indicate that despite reappearance of a small number of macrophages six months after implantation, Apaceram is useful for reconstructive surgery.     

New ring-opening polymerization via a π-allylpalladium complex

Summary A binary system of a palladium complex as catalyst and zinc alkoxide as initiator conducted a novel ring-opening polymerization of cyclic carbonate, i. e., 5,5-dimethyl-4-ethenyl-1,3-dioxan-2-one. The polymerization proceeded along with releasing carbon dioxide to produce the corresponding polyether. The -allylpalladium complex generated from the monomer with the catalyst is the key intermediate for this new polymerization. The propagating end is zinc alkoxide, which nucleophilically attacks the monomer activated as the -allylpalladium complex in the propagation.     

Thermal strain of high strength polyethylene fiber in low temperature

High strength polyethylene fiber (Toyobo, Dyneema® fiber: hereinafter abbreviated to DF) has a negative thermal expansion coefficient. Relation between fiber structure and thermal strain of DF used as reinforcement of DF reinforced plastic (DFRP) for cryogenic use was investigated. The crystallinities and orientation angles of several kinds of polyethylene fibers having different modulus from 15 to 134Gpa (herein after abbreviated to DFs) were measured by NMR and X‐ray. We obtained the parameters of the mechanical series‐parallel model composed of crystal and amorphous by crystallinity and modulus. Thermal expansion coefficients of DFs were estimated by mechanical series‐parallel model. All DFs having different modulus showed negative thermal expansion coefficients in the temperature range from 180 to 300K, and absolute values of those markedly increased by increasing tensile modulus of DF. The estimated thermal expansion coefficients showed negative values, and thermal strains showed a similar curve to observed ones mostly. Average thermal expansion coefficients in the temperature range from 180 to 300K estimated by mechanical model agreed with the observed ones. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2918–2925, 2004     

Combination of bottleneck feature extraction and dereverberation for distant-talking speech recognition

The performance of speech recognition in distant-talking environments is severely degraded by the reverberation that can occur in enclosed spaces (e.g., meeting rooms). To mitigate this degradation, dereverberation techniques such as network structure-based denoising autoencoders and multi-step linear prediction are used to improve the recognition accuracy of reverberant speech. Regardless of the reverberant conditions, a novel discriminative bottleneck feature extraction approach has been demonstrated to be effective for speech recognition under a range of conditions. As bottleneck feature extraction is not primarily designed for dereverberation, we are interested in whether it can compensate for other carefully designed dereverberation approaches. In this paper, we propose three schemes covering both front-end processing (cascaded combination and parallel combination) and back-end processing (system combination). Each of these schemes integrates bottleneck feature extraction with dereverberation. The effectiveness of these schemes is evaluated via a series of experiments using the REVERB challenge dataset.     

Resonant metal-mesh bandpass filters for the far infrared

The spectral performance of freestanding resonant metal-mesh bandpass filters operating with center frequencies ranging from 585 GHz to 2.1 THz is presented. These filters are made up of a 12-μm-thick copper film with an array of cross-shaped apertures that fill a circular area with a 50-mm diameter. The filters exhibit power transmission in the range 97-100% at their respective center frequencies and stop-band rejection in excess of 18 dB. The theoretically predicted nondiffracting properties of the meshes are experimentally verified through high-resolution beam mapping. Scalability of the filter spectra with mesh dimensions is demonstrated over a wide spectral range. Several modeling methods are considered, and results from the models are shown.     

Optimal configuration for the self-identification of a two-dimensional variable geometry truss

This study addresses the optimal changes in geometry of a two-dimensional variable geometry truss (VGT) to identify the stiffness matrix of the truss using the concept of self-identification. The optimization of the geometry changing of the VGT is a problem of selecting the optimal combination of multiple design variables from a large number of candidate sets. This study proposes a simple optimization method for determining a set of optimal geometric parameters; in this method, the approximated mode shape matrix obtained using spline interpolation techniques is used to calculate the objective function for self-identification. The objective function used in this paper is a function of the condition number of the coefficient matrix of a linear matrix equation and a criterion for self-identification. The proposed algorithm can be used to reduce the number of actual vibration tests required for measuring the mode shapes and modal frequency while it maximizes the objective function. Numerical experiments are conducted to investigate the relationship between the convergence characteristics of the optimization and the target vibration modes. The effectiveness of the optimized geometry changing is verified by comparing the identification error for the uniform geometry changing, the optimized one for the three lower modes of the VGT, and the one found by a classical QR decomposition. Furthermore, the numerical results show that the identification sensitivity with respect to noisy data is reduced by the optimization.     

数据库财务管理系统中的后台监督

本文借鉴某些大型机上的系统日记的思想,为自己的财务系统建立一个后台监督系统,以解决凭证数据库的数据修改问题以及由此引起的完整性和安全性问题。     

Performance Comparison of Circuits for Pole‐Mounted STATCOM Using SiC Devices

The recent years have seen an increasing trend in the cumulative installed capacity of distributed generators. As a result, voltage management may become difficult in existing power distribution systems in the future. A STATCOM (STAtic synchronous COMpensator) is a promising option for solving this problem because it can control reactive power rapidly and continuously. For a distribution system, STATCOM needs to be pole‐mounted to realize its low cost. However, a transformer for a STATCOM is large and heavy, and hence it is difficult to install a STATCOM on a distribution pole. We adopt a transformerless STATCOM to reduce STATCOM size and use SiC devices with low‐loss performance to obtain a more compact and efficient STATCOM. There are a large number of circuits available for a STATCOM, and there has been considerable research on performance comparisons among these circuits. However, these comparisons were drawn under different conditions, including switching frequency and level number for the circuits. In addition, these comparisons do not include the use of SiC devices. We made an equitable comparison for a 100 kVa pole‐mounted STATCOM using SiC devices. We discuss the performance and characteristics of each circuit in terms of efficiency and volume.     

Boiling heat transfer characteristics of a sulfuric-acid flow in thermochemical iodine–sulfur cycle

The Japan Atomic Energy Agency has been conducting research and development on the thermo-chemical iodine–sulfur (IS) process, which is one of the most attractive water-splitting hydrogen production methods that uses nuclear thermal energy. The sulfuric acid decomposer is one of the key components of the IS process. The boiling heat transfer coefficients of sulfuric acid solutions are required to design the sulfuric acid decomposer. These coefficients were measured in aqueous solutions where the mole fraction of H₂O ranged from 0.17 to 0.37 (heat flux range from 16.9 kW/m² to 5.6 kW/m²) and compared with the empirical correlations formulated for binary mixtures. A combination of the Stephan–Körner correlation, using the empirical constant A₀ = 2.00, and the Nishikawa–Fujita correlation was used to predict the experimental results with an accuracy of ±10%.     

An analysis of the length of hospital stay for cataract patients in Japan using the discrete-type proportional hazard model

We analyze the length of hospital stays of patients hospitalized for cataract and related diseases (Diagnosis Related Groups (DRG) 2041) in Japan, utilizing the data pertaining to 3436 patients on whom one-eye lens operations are performed. We use the discrete-type proportional hazard model to analyze variables that may affect the length of stay.