Astrogeodetic deflections of the vertical in Japan with respect to Bessel′s ellipsoid are mostly directed to the northwest due to the unfitness of Bessel′s ellipsoid to the geoid in and around Japan. This kind of unsuitableness for the position of Bessel′s ellipsoid is based on the assumption that the astrogeodetic deflection is taken as zero at the geodetic datum . A correction computation is desired for best-fitting the ellipsoid to the geoid. Astrogeodetic deflections of the vertical in Japan have been observed at 324 trian gulation points during the period from 1947 to 1977 by the Geographical Survey Insti tute. And the geoidal heights in and around Japan have been computed by the Hydrographic Department of the Maritime Agency. The present study is devoted to transforming the Geodetic Reference System of Japan into an ellipsoid best-fitting the Japan Hydrographic Department Geoid. The result shows that the correction for the deflection of the vertical at the Tokyo geodetic datum amounts to ξ0=-11″.98 and ηo= +10″.24. These values are well consistent with the results previously obtained by the various methods.

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To test the reliability of the parameters of a best fitting ellipsoid derived from the astrogeodetic deflections of vertical in Japan new computations are carried out changing the conditions, that is, the type of an observation equation and the number of parameters, using new deflection data at 342 stations in Japan. The result shows that the shape and dimension of a best fitting ellipsoid are very sensitive to these conditions. This may indicate that the data area is too small to determine an optimum best fitting ellipsoid from only the astrogeodic deflections of vertical in Japan.

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This report is a continuation of two reports[1, 2] published previously.
An arbitrary geodetic network has been adjusted strictly on the surface of a reference ellipsoid by using the Universal Program, whose program name is TO 16 G 4 for the electronic computer NEAC-2206 in the Geographical Survey Institute. It was necessary until now that the position of a station is given at least as a known station in a network.
The Universal Program has been improved so as to be available in a case such as all stations are unknown, too. In such a case Σp_iv_i² = min. is solved under conditions nΣi=1N_icosψ_iδλ = 0, nΣi=1M_iδψ_i = 0, where p_i and v_i are the weight and the small correction of individual observed value, M_i and N_i are the radii of curvature in meridian and prime-vertical at a station P_i (longitude = λ_i East +, latitude = ψ_i), δλ_i and δψ_i are the small corrections of λ_i and ψ_i. If we give known old values of the station P_i to λ_i and ψ_i, (N_i cos &psi_i;δλ_i, M_iδψ_i) is a displacement-vector V_i for a period from old survey to new survey. The solution of ΣV = 0 is found by means of another computation process that is not so elegant as the method above, too. It is the method that we give a station in a network its old known position and perform the computation of net-adjustment and find an average displacement-vector and subtract it from individual displacement-vector. Fig. 1 is a same geodetic network used in [1] for the purpose of explainning concretely the Universal Program. These two solutions are tested on the network. Input data in the latter method in that the position of a station P4 is known is shown in the first _??_, and other input data in the elegant former method by that solution of ΣV = 0 is obtained directly is shown in the second _??_. The difference between these two input data is that there are known stations or there are not known stations in them. The results of the two methods are shown in Table I. The values in the brackets in Table I are found briefly by additional manual computation. Perfect coincidence of two results proves that the Universal Program has been improved without making a mistake.

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Surveys of lake and seafloor sediments and topography are very important for improving fisheries catches and elucidating the mechanisms of earthquake occurrence. In order to carry out such surveys, it is necessary to develop a survey boat that can navigate even in relatively shallow and difficult-to-enter waters. In this research, we developed a compact and lightweight self-navigation survey boat that is easy to disassemble and carry. The research vessel we developed consists of a motor, a fish-finder, and a microcomputer (Raspberry Pi). In order to realize the proposed survey boat, we developed a new self-navigation control algorithm and conducted a practical experiment in the ocean to confirm its superiority.

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イベント情報サイトなどの情報源は，主に過去の大規模なイベントに関する情報を手に入れるために用いられる．そのため，小規模なイベントの情報を手に入れるための情報源が新たに必要である．本論文では，twitterからのイベントに関する情報抽出手法について提案する．イベントに関するツイートは時空間で密集して発信されるため，ツイートの集合に対して時空間クラスタリングを行う．出来たクラスタの中で，同じイベントに関する内容で構成されているクラスタ同士はクラスタの統合を行う．そのようにして出来たクラスタからイベントの開催時間，開催場所，イベントの内容に関する情報の抽出を行う．

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イベント情報サイトなどの情報源は，主に過去の大規模なイベントに関する情報を手に入れるために用いられる．そのため，小規模なイベントの情報を手に入れるための情報源が新たに必要である．本論文では，twitterからのイベントの検出手法について提案する．イベントに関するツイートは時間や空間において密集して発信されるため，時空間でクラスタリングを行う．また，イベントに関するクラスタに含まれるツイート同士の話題は，イベントに関する内容で共通しているという性質を持つ．そこで，ツイートの内容を解析しツイート同士の類似性を測ることで，イベントに関するクラスタを判別しイベントを検出する．

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　中部中国における8万点余に及ぶ三角網は,1963年米国陸軍地図局によつて南京原点・国際楕円体に基づき天文・測地的に調整された.この組織のうちで70点の天文・測地点の鉛直線偏差を用いHUNTERの公式によつて原点および準拠楕円体に関する諸元の計算をして次の値を得た.　適合する楕円体:a=6378689m,f=1:298.4.　楕円体標定の諸元:ξ0=+0".00,η0=-0".00,N0=-0.13m.　適合する楕円体は,今までに得た値に比してαがかなり大きい.また国際楕円体が適合しているとすれば,楕円体標定の諸元はξo=+0".00,ηo=+0".00,No=-0.50m.　一般的に国際楕円体は,中部中国以南Thailand, Indochinaの地域を通して現地に適合しているように見える,

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In digital maps, positions are usually given by latitude and longitude, while topographic maps and satellite images are projected on the UTM coordinate system. In order to overlay them, the map projections should be converted each other. In this report, we investigate error factors of the conversion and evaluate their accuracy. Based on these analysis, we propose a practical algorithm, of which accuracy is enough for the conversion of the topographic maps and satellite images.

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The bathymetry data obtained by multi-beam echo sounder is widely used and the amount is getting larger these days. But most of the existing systems to manage those data are made for common usage. So these systems cannot efficiently meet the demands varying by users who need more detailed bathymetry map for example. In this paper, first we suggest new data management system which improve these points. Next, two kinds of methods to correct errors of the bathymetry data are shown as functional components of new data management system. One is ray tracing in Earth ellipsoid and another is correction of error caused by horizontal acceleration in motion sensor. It was proved that the result of the new calculation method in ray tracing revises 5m of depth errors at a depth of about 5000m. And the error correction of the motion sensor after depth sounding was proved effective but needs more investigation.

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The mathematical model for a new adjustment of the Japanese Datum derived by the author previously is a rigorously three-dimensional system. The mathematical specifications for observations, reductions, and observation equations of terrestrial surveys are given. The final set of normal equation coefficients can be accumulated by summing over the partial normal equations. The equations for elimination of orientation unknowns and those for handling of the observation equations for Laplace azimuths, trigonometric leveling, and astrogravimetric leveling are derived.

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We can obtain horizontal deformation vectors of the crust of the earth from comparing new geodetic observation with old one in the same area under an appropriate assumption. The map of vectors varies according to the assumption. The map of vectors, that satisfies ΣV = 0, is generally believed to be very plausible. Fig. 2 is drawn under the assumption that the positions of two stations 202 and 205 are common in new and old surveys. The triangular mark in the same figure is the new volcano appeared suddenly in 194445. Fig. 2 changes to Fig. 4 under ΣV = 0. But it is obvious in this case that Fig. 2 is preferable to Fig. 4, because very little deformation is expected in the environs of the district as be seen in Fig. 3. Let p_i be such a value as be inversely proportional to average variation in angle at i-station. If we draw the new map of vectors with V_i-V₀again, where V_o = (Σp_iV_i)/Σp_o, it seems to be very plausible.

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Sixty percents of people in the world live in Asian area, and their economic activities earn twenty four percents of the total GDP all over the world. As the population increases and the economic activities, emissions of sulfur oxides and nitrogen oxides from combustion are increasing and the emissions cause not only local pollution but also global environmental pollution.
It is important to calculate the concentration of sulfur oxides that is emitted from the stack of large point sources. In this paper, a software package was developed to calculate the diffusion of sulfur oxides which is emitted from Asian large point sources by using the Japanese air pollution model, and this package was applied to diffusion problems by large point sources China, Korea and India's. The result is displayed as figures with GIS and the diffusion in each country was discussed.

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The Bessel ellipsoid which is adopted as the reference ellipsoid of the Japanese geodetic system is not satisfactory approximation as the figure of the earth. Moreover, at the geodetic datum, it deflects considerably from the world-wide ellipsoid. In order to obtain practical corrections to the existing coordinates of any station in Japan due to the above two factors, the equations of the longitude- and latitude-difference between two stations are expanded to the required accuracy. The actual calculation is made by adopting first the International Ellipsoid instead of the Besselian, and secondarily the round values of + 15″ (in latitude) and -20″ (in longitude) as the corrections at the geodetic datum to make the Japanese system in of conformity with the world-wide geodetic system. The numerical values are shown in the annexed figure.

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ACCで冬期道路を走行しているドライバの先行車に対する主観的リスク認知レベルを実車で計測し、冬期道路におけるACCの適応条件の検証を試みた。ドライバがACCを用いて先行車を追従中、先行車が減速し接近する場面を想定した。その結果、ACC走行時のドライバの主観的リスク認知レベルは通常運転に比べて大きくなった。また、先行車との接近時におけるTHW(Time Headway)とTTC(Time To Collision)を説明変数、主観的なリスク認知レベルを目的変数とする統計的モデルを推定した。モデルはTHWのみが有意となった。モデルと主観的なリスク認知レベルの結果から、ドライバが圧雪路面をACCで走行するときにTHW設定を長くすることで、通常運転と同等のリスク認知レベルとなる可能性が示唆された。

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