Structural characterization of 1,2-polybutadiene by 13C n.m.r. spectroscopy: 1. Signal assignment in hydrogenated polybutadienes

The configurational sequences of 1,2-unit in a series of hydrogenated syndiotactic 1,2-polybutadienes were investigated in relation to the sequence distribution of 1,2- and 1,4-units. The signals at 10.20–10.94 ppm were assigned to the methyl carbons in the isolated 1,2-unit, the 1,2-1,2 dyad sequence flanked by 1,4-unit, and the 1,2-1,2-1,2 triad sequence, in order of increasing magnetic field. The splittings due to the configurational sequences were observed in the signals, reflecting the dyad and triad sequences of the 1,2-unit, which were assigned by considering the relative intensity of the signals and also the chemical shifts of model polymers.     

Regularization of hypersingular and nearly singular integrals in the potential theory and elasticity

Both the hypersingular and nearly singular integrals, which appear in the hypersingular boundary integralequations and integral representations of the secondary fields, respectively, are regularized by the application of the superposition principle. Two kinds of the non-singular formulations, namely, those with the strongly singular and weakly singular kernels, are presented in this paper. The formulations are given in terms of the relevant boundary quantities and the collocation at element junctions is possible. Two- and three-dimensional problems are analysed simultaneously in a unique way for either internal or external problems of the potential theory and elasticity.     

Pancreatic carcinoma in remnant pancreas after pancreatectomy for mucinous cystadenoma

We report an unusual case of laryngomucocele occurring after subtotal laryngectomy. Laryngoceles generally have a congenital origin in a long-preexisting saccule, and their association with laryngeal carcinoma is well known. Laryngocele is usually favored by the increase of intraglottic pressure caused by the laryngeal carcinoma. However, an iatrogenic secondary laryngomucocele occurring after a surgical procedure is uncommon. We report in detail the physiopathologic conditions leading to the creation of this lesion.     

Still image transmission using ARQ over Rayleigh fading channels

The authors propose a new ARQ scheme suitable for image transmission over radio channels. The proposed scheme detects only serious degradation and so attains higher throughput performance than the conventional ARQ scheme     

An experimental study of conductive heating using a concentric double-electrode applicator

With hyperthermia for treatment of superficial tumors in mind, a prototype applicator with two electrodes arranged concentrically on a disk was designed for efficient local heating, and a basic heating test was carried out. Frequencies as low as 200 kHz were used in order to simplify the configuration of the power device. The applicator consists of two electrodes, a circular inner electrode and another looped outer electrode, arranged concentrically. Water was passed through the applicator as a cooling mechanism; it was placed in direct contact with the target tissue to be heated and then charged with electricity. In the heating test using a phantom, oval hot spots were noted below the inner electrode. Using cooling water at 3 degrees C and 8.2 W, an isothermal line of 45 degrees C was located at a 5-mm radius circle around the central axis with 9 mm depth. A similar temperature distribution map was obtained in heating tests on the thigh muscle of a mongrel adult dog. The temperature distribution maps obtained from these tests corresponded closely with the results of theoretical analysis carried out according to the finite-element method. Since a comparatively low frequency was employed for this applicator the power device was simplified, which made adequate heating possible with low electric power. The temperature distribution map indicated that efficient local heating of superficial tumors could be achieved.     

Direct Observation of the Collection Process for Dust Particles from an Air Stream by a Charged Water Droplet

One of the most effective precipitation methods for submicrometer particles is the charged droplet scrubber. The dust collection in the charged droplet scrubber is considered to consist of some processes with respect to the interaction between charged dust particles and a charged water droplet. That is, the charged dust particles are attracted to, collide with, adhere to, penetrate into, rebound from, accumulate on, and reentrain from a charged water droplet. The direct observation of the collection process for dust particles by a charged water droplet was conducted by using the experimental setup designed by the authors. It was found from the experiments that particles with good wettability were captured inside the water droplet, particles with poor wettability floated at regular intervals on the droplet surface, and particles with medium wettability were trapped on or inside the water droplet. When particles were trapped on the droplet surface the growth of dendritic depositions was found, and their behavior was very distinct from those obtained on the fibrous filter due to the fluidity of the droplet surface. The deposition mechanisms of charged particles on the charged water droplet are discussed qualitatively.     

A multiport page-memory architecture and a multiport disk-cache system

Everlasting demands for solutions to ever growing computation problems and demands for efficient means to manage and utilize sophisticated information have caused an increase in the amount of data necessary to handle a job, while drastic reduction in CPU prices is encouraging massive parallel architectures for gigantic data processing. These trends are increasing the importance of a large shared buffer memory with 10³～10⁴ simultaneously accessible ports. This paper proposes a multiport page buffer architecture that allows 10³～10⁴ concurrent accesses and causes no access conflict nor suspension. It consists of a set of memory banks and multistaged switching networks with controllers that control each row of the networks. Consecutive words in each page are stored orthogonally across banks. Memory interleaving may be applied to improve access rate in consecutive retrievals. When used as a disk cache memory, it decreases the number of disk accesses and increases both the page transfer rate and the maximum number of concurrent page accesses.     

A study on the electric field distribution in an automobile bodyfor an antenna system mounted inside the body

The electric field distribution in an automobile body must be known when developing an antenna system mounted inside the car body for mobile communication. A microwave simulation experiment was carried out in an electromagnetic anechoic chamber using 4 GHz band signals and a miniaturized automobile. The automobile model used in this simulation experiment was about 1/15 of the size of the actual automobile under consideration. A simpler box-type model with large apertures was also studied. The internal electric field distribution measured in the box model was estimated to be a combination of the resonant TE_Pmn modes excited in the box. which acted as a resonant cavity. The spatial and frequency dependence of the internal automobile's electromagnetic field for each model is plotted for the frequency range 3-5 GHz