By comparing the electron density variations in the F2 region during the night at Kokubunji and Yamagawa it has been made clear that, if we assume a linear law of electron disappearance and some-what higher temperature of the upper atmosphere at Yamagawa than at Kokubunji, the observational data fit theoretical expectation rather well, but a quadratic law can hardly be reconciled with the observations, unless recombination coefficient changes markedly with height.

抄録全体を表示

PAメソッドの臨床経験及び音響振動療法に関する各機関の研究から、PAによる音響振動の刺激は感覚神経を通って脳に伝えられ、中枢神経、運動神経、自律神経、内分泌系に作用して心と体を沈静化すると考えられている。心の面では、不安・抑うつ・不眠等に明らかな効果が見られ、てんかん患者の症状が改善することもある。また、心理学者であるペトリ・レイコイネンによるPAの刺激に対する脳波の研究では全帯域での振幅の減少が認められ、深いリラックス状態にあることがわかった。このようなことから、PAの刺激は中枢神経系において抑制性神経伝達物質GABAの作動に影響を及ぼす可能性を示唆している。

抄録全体を表示

The equations for the field strength of the diffracted electromagnetic by mountains are derived for any polarization of the and any positions of the transmitter and receiver, without making important assumption except that the change of the mountain characteristics within the distance of a length is sufficiently small. Also, the general equation for the contribution of the field strength of any given picture of path which consists of the free space propagation parts and the diffraction or reflection parts by mountains is obtain.

抄録全体を表示

The physical meanings of concepts such as group velocity and path, are first carefuly examined and mathematically founded, and it is then investigated whether the significant concepts of group velocity and path do exist or not, when the Maxwell field energy is lost in a medium. It is concluded that, in a rigorous sense, they generally do not exist in absorbing non-uniform medium, and that, when the energy loss in a medium is sufficiently small that only the first order changes in group velocity and path due to the energy loss are required to be taken into account, they approximately exist and are concordant with the ones obtained when the field energy is not lost in that medium, so that it is anyhow meaningless to discuss their changes due to the energy loss in a medium.

抄録全体を表示

The existence of some correlation between the geomagnetic storm and the ionospheric F2 layer disturbance has long been investigated since the early stages of ionospheric researches. Recenty, this problem has been studied by many investigators not only from geophysical interest but also under the necessity of improving radio communications.
The main course of investigation on F2 disturbance, which has been studied by the author for the last three years, is summarized as follows:
(1) The separation of variations in f⁰F2 and h′F2 associated with geomagnetic storms into two parts depending on the universal time and local time, the so-called Dst(F2) and S_D(F2), respectively, was clarified.
(2) The devlopment process of the F2 disturbance was investigated in respect to each of D_st(F2) and S_D(F2). It is concluded that S_D(f⁰F2) exists in the earlier stage of geomagnetic storm and D_st(f⁰F2) grows in the comparatively later stage.
(3) The latitudinal and seasonal characteristics were shown.
(4) Investigations were made in the behaviour of the F2 layer according to the different levels of geomagnetic activities. Results showed that the F2 layer disturbance was generally in proportion to the geomagnetic activities, except for D_st(f⁰F2) variation in winter.
(5) As to the successive yearly variation of, ionospheric disturbance, it was found that the phase of S_D(F2) would lag behind according to the decrease of sunspot activity.

抄録全体を表示

The world-wide patterns of the F2-region disturbance and their development process with the geomagnetic storm-time were examined with the comprehensive world-wide data of F2-layer.
The average disturbance in f⁰F2 during the main phase of the associated magnetic storm, so-called D (f⁰F2), was derived with respect to geomagnetic latitude and local-time, and it was separated into the Dst (f⁰F2) and Ds (f⁰F2) component. It will be shown in this analysis these two components play an important role in the ionospheric storms, and not only their range, but also their phase are controlled by the magnetic activity.
The average development course of the ionospheric storm and the mode of the Ds (f⁰F2), changing regularly with storm-time, were studied. The phase of the Ds (f⁰F2) during the active stage of magnetic storm is almost uniquely dependent upon local-time, but after the activation ceases, the pattern of the disturbance moves together with the rotating earth.
Detailed analysis was made on the progressive aspects of the individual disturbances in the northern hemisphere accompanied with some typical severe magnetic storms.

抄録全体を表示

Storm-time variation of WWV 20Mc/s field intensity at Hiraiso is examined for about 50 geomagnetic storms during August 1957-February 1959. An abnormal increase of field intensity of WWV 20Mc/s appears from about 12 hours before a geomagnetic storm sudden commencement to a few hours after it. It is found that the storm-time variation of f₀F₂ deviation from the monthly median also shows pre-SC augmentations for the corresponding storm-time interval at Winnipeg and Fairbanks, which are located at approximate apexes of the Washington-Hiraiso 3 hops path. This close relation between these pre-SC phenomena suggests that the pre-SC intensity increase of HF polar path may be useful for the radio warning especially for periods of the solar minimum activity.

抄録全体を表示

A study is made of movements in the Es region by means of measurements of pulsed waves at 1.85Mc/s emitted from a Loran station and of ionospheric vertical soundings.
Moving clouds in the Es region of large lateral dimensions are usually observed during the night either isolated or grouped like the wavy clouds sometimes seen in the troposphere. The speed of about 80m/sec and the direction towards the southwest are deduced from various kinds of observations.
It is inferred from this experiment that the observed Es layer is of two types: the first is the horizontally stratified thin layer produced by electromagnetic re-distribution due to the laminar wind shear and the second consists of a number of elongated regions of excess ionization, being of the order of 100km long and 10km wide, which may be caused by hydrodynamical instability in the wind shear prevailing there.

抄録全体を表示

Ionospheric absorptions of VLF emissions at the auroral zone have been calculated along a geomagnetic line of force connecting with the earth's surface at geomagnetic latitude of 64° by using the longitudinal approximation of the Appleton-Hartree formula and data of rocket sounding at Ft. Churchill and of auroral luminosity profile at College, Alaska.
Ionospheric absorptions at 4kc/s between 50km and 170km height are of 33.1dB, 15.4dB, 16.9dB, and 2.2dB for a daytime ionosphere during total polar black-out, a quiet ionosphere near noon, a midnight ionosphere during diffuse aurora, and a quiet ionosphere at winter midnight respectively. Therefore the lack of VLF emissions during total polar black-out at high latitudes may be due to the marked increase of the absorption in the ionosphere, especially in D layer.
On the other hand, it seems likely that particles producing auroras and geomagnetic disturbances around E layer do not cause considerable absorption of the VLF emissions, and that the power of VLF emissions is originally weak in the exosphere on night side at the auroral zone. The absorption of 15.4dB in the quiet ionosphere near noon suggests that the original power of VLF emissions in the exosphere is of the order of 3.5×10^-13-3.5×10^-15W.m.^-2(c/s)^-1 in the daytime. The diurnal variation in maximum chorus frequency at high latitudes may be explained by relative increase of ionospheric absorption during the daytime for frequencies above a few kilo-cycles.

抄録全体を表示

Ejection and prapagation of the particles which excite abnormal ionization in the polar upper atmosphere are investigated from some statistical considerations on ionospheric data f-min and cosmic radio observation by riometer.
Relations between the flares and the polar-cap blackouts insist the trapping of particles into the cloud which would be responsible for the geomagnetic disturbances; that is, a part of the energetic particles ejecting from the flare propagate with relativistic velocity in interplanetary space along the twisted solar magnetic line of force extending to the earth and excite the S-type polarcap blackouts having sudden onset within a few hours after flare; on the other hand, another part of the energetic particles ejecting from the flare is trapped into the cloud and is carried with rather low velocity, then the particles would reach the earth by leaking from the cloud and excite the G-type polar-cap blackouts having gradual onset about 10 hours before commencement of geomagnetic storms.

抄録全体を表示

A new spectoscope recording continuously the amplitude-frequency spectrum of VLF atmspherics has been developed. The receiver sweeps the frequency giving complete coverage of the band of 5-70kc/s repeatedly and the output is displayed on an intensity modulated cathode-ray tube, which is photographed on a slowly moving film.
Observations have been carried out and it appears that the result provides an excellent experimental base for the mode theory of VLF ionospheric propagation. It is found that the frequency-spectrum of distant atmospherics shows a broad intensity maximum around 10kc/s and decreases its intensity towards higher frequencies with undulating peaks. Marked selective absorption bands appeared in the spectrum are variable according to the time of day, and they might be assoiated with cut-off frequencies of the waveguide bounded by the earth and the ionosphere. The solar flare effect on VLF atmospherics propagation is also revealed, which indicates a sudden shift of the spectrum to higher frequencies owing to the increase of ionization and the lowering of a reflecting height of the ionosphere.

抄録全体を表示

A detailed investigation is made of a severe magnetic storm on October 28th 1951, using world-wide simultaneous geomagnetic and ionospheric data. It has been found that an outstanding electrojet stream comparatively short-lived appeared near the southern edge of the auroral zone at the end of the main phase of this storm. The ionospheric disturbance associated with this electrojet was anomalous; the electron density of the F2 layer above the electrojet stream increased suddenly to more than 10⁶ electrons per cm³ and then dropped below normal after the disappearance of the current stream.
Although any existing theory of ionospheric storms can not explain satisfactorily this anomalous change, two possible mechanisms are suggested from some consideration of the direct association of geomagnetic and ionospheric variations. One is the effect of the incomming corpuscular precipitation into the ionosphere and consequently the formation of a new F2 layer due to the increase of ionization. The other is due to the vertical drift of electrons produced by the interaction of the geomagnetic field with the currents in the F2 region returning from the main electrojet formed in the E region.

抄録全体を表示

An overview is given regarding experimental activities in the field of hypersonic flow. After a brief introduction into the history of hypersonic ground based facilities modern high-enthalpy wind tunnels are described including their capabilities and flow diagnostic techniques. After the HERMES technology program came to an end in Europe, an ESA technology program, called Manned-Space-Transportation Program(MSTP)has been initiated among several institutions in Europe to preserve the knowledge in hypersonics. Besides of the ESA activities 3 Sonderforschungsbereiche(centers of excellence)exist at German universities. These centers are related to hypersonic flow research;they are supported by the Deutsche Forschungsgemein-schaft DFG.

抄録全体を表示

 Currently, the estimation of wind-waves on coastal waters is commonly done in practice on structured mesh. However, when complex geometries arise (for instance, irregular coastlines, islands and breakwaters) multistage nesting with smaller grid spacing which entails high computational cost is required on structured mesh and even then it is sometimes difficult to get accurate bottom topographical approximation of only required areas. In contrast, since unstructured mesh can perform detailed geometrical approximation only at necessary places, it is expected to reduce the computational cost while securing the accuracy of the bottom topographical approximation.

 Hence, the objective of this study is to analyse wind waves with SWAN (Simulating WAves Nearshore) model, which is commonly used in practice for nearshore

analysis, on structured mesh and unstructured mesh and, thereby to find out an effective approach to use SWAN model in future practice. The behaviour of SWAN model on structured mesh (ST-SWAN) and on unstructured mesh (UNST-SWAN) was analysed and advantages of UNST-SWAN over ST-SWAN were discussed. Wind-waves were estimated during the arrival of Typhoon with ST-SWAN and UNST-SWAN. Wind- characteristics obtained from both ST-SWAN and UNST-SWAN were basically consistent. Considering the advantages of UNST-SWAN, an effective approach to apply SWAN model in future practice by combining both structured and unstructured mesh where necessary was proposed during this study.

抄録全体を表示