http://hdl.handle.net/11133/117 1994-03 Sun, 05 Apr 2026 17:00:30 GMT 2026-04-05T17:00:30Z http://hdl.handle.net/11133/969 タイトル: 遠心載荷模型実験に関する基礎実験 著者: 成田, 国朝; 奥村, 哲夫; 大根, 義男 抄録: In this paper, several features and efficiencies of the geotechnical centrifuge apparatus set up at AIT in March, 1993 are first outlined. In order to confirm effective ways of utilizing the centrifuge and to acquire basic experimental techniques, some fundamental studies were carried out on the calibration of pick-ups and the measurement of earth and pore-water pressures in water and sand deposits. Disscussions were then made on the effects of side friction in the container and stress concentration and arching of soils around pick-ups on the precise measurement of earth pressures. Test results reveal that in the calibration of earth pressure pick-up, appropriate correction is needed for enertia force and soil properties, and that the effects of side friction and arching on earth pressure measurements are strongly dependent on the particle size. Wed, 30 Mar 1994 15:00:00 GMT http://hdl.handle.net/11133/969 1994-03-30T15:00:00Z http://hdl.handle.net/11133/970 タイトル: Generalized Short Time DFTのヒルベルト変換器への適用とその特性 著者: 岸, 政七; 小崎, 康成 抄録: Instantaneous spectrum concept is a promising solution to effectively developing key devices for economical communication systems. An exact realization of the Hilbert transformer has been previously discussed with employing new concept of instantaneous spectrum defined by ST DFT. The Hilbert transformer used in SSB or RZ SSB modulator provides with indispensable function for eliminating one sideband from output signals to efficiently reduce occupied spectrum over radio channels. A new class of signal processing is introduced by generalized short time DFT, in which sub-channels are arbitrary adjusted on the objective frequency domain. Another implementation of the noble Hilbert transformer is discussed with employing this ST gDFT. Restricting the ST gDFT within causality, phase shifting error of implemented Hilbert transformer is examined to be so accurate as detecting no error by micro degree order. Simultaneously, its amplitude error is shown to be less than 0.01dB. Wed, 30 Mar 1994 15:00:00 GMT http://hdl.handle.net/11133/970 1994-03-30T15:00:00Z http://hdl.handle.net/11133/964 タイトル: 締め固めた土の動的性質と盛土の地震時安定性評価について 著者: 伊藤, 祐仙; 大根, 義男; 成田, 国朝; 奥村, 哲夫 抄録: The effects of compaction conditions, density and water content, and pre-compression stress history on dynamic strength and deformation properties, modulus of rigidity (G) and damping factor (h), of compacted cohesive soils were investigated through cyclic triaxial tests, and discussions were made on their use in evaluating seismic failure and slope stability of earthfills. A few conventional practical formulae were proposed in these element tests of estimating the undrained cyclic strength and the dynamic modulus of rigidity through ordinary static compressive strength and deformation modulus. FEM dynamic response analysis was then conducted for a model earthfill to know pre-compression effects on the response behavior, distribution of rigidity and local stability factor, in the evaluation of seismic slope failure. Wed, 30 Mar 1994 15:00:00 GMT http://hdl.handle.net/11133/964 1994-03-30T15:00:00Z http://hdl.handle.net/11133/965 タイトル: Short Time DFTによる狭帯域化技術を用いた差分検波π/4-shifted DQPSKの大容量化 著者: 岸, 政七 抄録: This paper presents the narrowing bandwidth of π/4-shifted DQPSK, which has previously achieved using raised cosine filter, at 1.62bit/Hz efficiency, with based on the Nyquist Kaiser filter and generalized short time DFT (ST gDFT) demodulator. Such degradations as caused from Gaussian thermal and fading click noise are desmeared through ST gDFT to improve efficiency more than 1.80bit/Hz. Wed, 30 Mar 1994 15:00:00 GMT http://hdl.handle.net/11133/965 1994-03-30T15:00:00Z