Development of a numerical wave tank for analysis of nonlinear and irregular wave field

A numerical wave-absorption filter has been developed for an open boundary condition in the analysis of nonlinear and irregular wave evolution. The filter is composed of a simulated sponge layer and Sommerfeld's radiation condition at the outer edge of the layer. The wave-absorption characteristics of the filter have been investigated by applying the linear potential theory and a two-dimensional nonlinear boundary element model. In both cases, the filter is found to he applicable for a wide range of wave parameters. In order to realize an idealized “numerical wave tank”, the present model also incorporates a nonreflective wave generator in the computational domain composed of a series of vertically aligned point sources. Numerous numerical experiments demonstrate that the present approach is effective in generating an arbitrary wave profile without reflection not only at the open boundaries but also at the wave generator.     

Deposition of Sulfate,Chloride and Sodium at Japanese Meteorological Observatories and on the Western North Pacific

Abstract

A simple plastic sampler was tested to get the information on the deposition amount of chemical components throughout Japan and the neighbouring regions. Polypropylene cylinders of diameter 117 mm which contained 300ml pure water were set in the observation fields and kept open for one month. At the end of the month the samplers were covered with caps and sent to Meteorological College, Kashiwa, Chiba. The sample solutions were filtered through Millipore filter (0.45μm pore size) and used for the determination by ion chromatography, atomic absorption and flame emission analyses. Monthly deposition amounts of sulfate, chloride and sodium ions were determined simultaneously at 21 Japanese meteorological observatories in June and October 1987. Similar samples were also set on the upper deck of RV Ryofu-maru for 4–7 days during cruises across the western North Pacific in 1987 and 1988. The deposition amount of SO₄(excess) (SO₄–Na × SO₄(seasalt)/Na(seasalt)) was calculated. The strongest source regions of SO₄(excess) were found to be on the Pacific side of Honshu, where big cities such as Tokyo and Osaka are situated. The deposition amount generally decreased depending upon the distance from these sources. Another strong source region of SO₄ (excess) was Kagoshima. It is suggested that the deposition at this station was influenced by the volcanic activity of Mt. Sakurajima, because the deposition amount of Cl(excess) was also found to be high, reflecting the composition of the volcanic gases of this region.     

Layered scalable coding of multispectral images based on visible component separation

This paper presents multispectral image coding methods based on visible component separation techniques. By coding the visible components separately from other spectral components, the color information can be used without decoding the whole multispectral image. Two types of separation techniques are introduced: one is a direct separation of visible and invisible layers, while the other is a scalable separation. In the scalable separation, visible components are first compressed to produce the base layer bitstream. The enhancement layer data include not only invisible components but also the information on the distortion of the coded visible components. Such a separation technique improves the accuracy of decoded multispectral images especially when visible components are highly compressed. The performance of the proposed methods was evaluated for different bit allocations to visible components. In general, the coding performance reduces when data are divided and coded separately to incorporate scalabilities. Nonetheless, it is found that the proposed scalable approach realizes a peak signal-to-noise ratio PSNR value comparable to that achieved by employing JPEG2000, which incorporates no scalability.     

Degradation of MOSFETs on SIMOX by irradiation

Results are presented of a study on the degradation and recovery of the electrical performance of MOSFETs processed on SIMOX substrates, subjected to 1 and 2 MeV electron and to 20 MeV alpha-ray irradiations. The damage coefficient for alpha-ray irradiation is about three orders of magnitude larger than the one for electron irradiation, which is attributed to the difference of incident particle mass and the possibility of nuclear collision during radiation damage.     

Effect of irradiation in InGaAs photo devices

Results are presented of an extended study on the degradation of electrical and optical performance and the induced lattice defects of In_0.53Ga_0.47As p-i-n photodiodes, subjected to a 20 MeV alpha-ray irradiation. The difference in radiation damage with 1 MeV fast neutrons and 1 MeV electrons is discussed taking into account the energy transfer. The radiation source dependence of performance degradation is attributed to the difference of mass and the probability of nuclear collision for the formation of lattice defects.     

Hierarchical Clustering Method for Extraction of Knowledge from a Large Amount of Data

The introduction of information systems in the medical field has made it possible to accumulate a large amount of health care examination data. Analysis of such data could yield valuable new knowledge about health and disease. In this paper, we propose a method for the analysis of large amounts of medical and health care data, especially images or signals. The proposed method treats data in a multidimensional space without any pre-processing, and the data is classified into groups according to the criterion. The criterion used in this paper is to maximize likelihood calculated from the probability density, which is given by the Parzen estimation method. The result of classification is expressed by a binary tree structure as a hierarchy of clusters. We applied this method to computer-generated data and practical electrocardiogram data, and the results showed its validity.     

Topographic Measurement Of Internal Surfaces Using a Sequence of Stereo Charge-Coupled DeVice Endoscopic Images: (1) Method

In endoscopic diagnosis, there has been a strong requirement to measure the internal surface topography of the rectum or esophagus. Accurate measurement, however, is very difficult, because the object is usually observed from an inclined view. In this paper, we propose a method to overcome this difficulty utilizing sequential stereo-pair images; the relative shape is roughly measured from sequential images taken by one of the change coupled device (CCD) cameras, and the size is determined by stereo-pair matching using the measured shape. A coarse-to-fine approach is also used to improve the resolution of topographic measurement. Through a basic experiment using a monocular CCD endoscope and a polyp phantom, the proposed method is confirmed to improve measurement accuracy in comparison with conventional methods.     

A fundamental characteristic and image analysis of liquid flow in an AW type EHD pump

Non-intrusive two-phase fluid pumping based on an electrohydrodynamically (EHD) induced flow phenomenon with free liquid surface exposed to gas-phase corona discharges is experimentally investigated. Dielectric liquid flow generated near a corona discharge electrode progresses toward an inclined plate electrode, and then climbs up the surface against the gravitational force for an air-wave (AW) type EHD pump. The AW type EHD pump is operated on ionic wind field along the inclined plate electrode. The pumping performance of time-averaged liquid flow rate and the liquid-phase flow motion are characterized. The liquid flow characteristics related to a dimensionless parameter of corona discharge fields are presented.     

Optical Interpolation of Volume Data Using Pseudo Color and an Electro-Optical-Hybrid-System

Volume data is interpolated using pseudo color and an electro-optical-hybrid-system. The method proposed in this paper is called optical interpolation. The visualization of a volumetric array of computed tomography data is achieved using the optical interpolation technique in combination with the optical model and the electro-optical-hybrid-system. To show the advantages of optical interpolation, the results are compared with those obtained by the traditional technique.     

Investigation of the novel mixed-mode stationary phase for capillary electrochromatography. II. Separation of amino acids and peptides on sulfonated naphthalimido-modified silyl silica gel

The potential of 3-(4-sulfo-1,8-naphthalimido)propyl-modified silyl silica gel (SNAIP) as a mixed-mode stationary phase for capillary electrochromatography (CEC) was investigated for the separation of charged analytes, taking four amino acids (tyrosine, phenylalanine, tryptophan, histidine) as model analytes. The elution process of these charged analytes in CEC with SNAIP was dominated by a combination of both electrophoretic process and chromatographic process involving hydrophobic as well as electrostatic interactions. In order to study the retention mechanism, the CEC retention factor k* and the velocity factor ke* were measured for the amino acids, which allowed the assessment of the respective contribution from the differential processes underlying the separation. Migration and retention could be mediated by changing various mobile phase compositions, including buffer pH, buffer concentration, and concentration of organic solvent. Based on the results obtained by separation of the amino acids, the separation of eight peptides (Gly-Val, Gly-Phe, Gly-Ile, Gly-His, Gly-Lys, Lys-Lys, Gly-Gly-Gly, Gly-Gly-His) was attempted. A good separation was achieved under an isocratic elution with a mobile phase consisting of 35 mM phosphate buffer (pH 3.8) and 40% methanol.