チビサラグモは主にスギ林床に生息し、リター上に造網するクモである。本研究は、個体群と局所という2つの階層レベルで生じているプロセスに注目し、チビサラグモの個体群密度の決定機構を明らかにすることを目的とした。まず、野外の15個体群を対象に、局所レベルでの個体数とその制限要因(造網に必要な足場の量、以下足場量)との関係性を調査した。その結果、多くの個体群で局所レベルにおける個体数と足場量との間に正の関係があったが、足場量が多い個体群ほど局所レベルでの足場量当りの個体数が多いことが明らかになった。このシステムでは、以下の2つのプロセスが密度決定に関与していると考えられた。1)足場量が多い個体群では、造網場所移動時の死亡率が低くなることで高密度になる、2)それが局所レベルでの足場をめぐる競争を強め、密度を低下させる。　これらの仮説を検証するため、まず広範囲での足場量を操作した実験を行った。その結果、足場量が多いほど、クモの死亡率が低くなることが示された。また以下の2つの野外実験から、足場量が多い個体群ほど、密度依存的な死亡が高くなることが示された。1つめの実験では自然個体群でクモ除去区を設け、除去区への移入率から移動頻度を推定したところ、足場量が多い個体群ほどクモの移動頻度が高いことがわかった。次に、足場量を等しくしたでクモの移動頻度を操作する実験を行ったところ、高い移動頻度は死亡率を高めることがわかった。以上のことから、個体群レベルでの足場量増加→移動時の死亡率低下による個体群レベルでの高密度化→局所レベルでの高密度化による足場競争の強化→個体群レベルでの密度の低下、という2つの階層間で生じる一連のプロセスにより、個体群密度が決定されていることが示唆された。

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Originally, the ultimate goal required in loudspeaker systems is to realize flat frequency character istics. However, from the pleasant sound standpoint, loudspeaker systems with flat frequency characteristics do not all w ays produce testy sound. We i ncorporate the movable sound mechanism in the resonance port of the loudspeaker systems. By automa tically synchronizing the movement with music, the Helmholtz resonance frequency is controlled to the frequency of sound to be enhanced. As a result, l oudspeaker systems in which the resonance frequency changes in the real-time manner are developed. These loudspeaker systems also have the visual entertainment nature that a resonance port moves to real-time manner according to music. We played music using these loudspeaker systems, and evaluated them in sense using the AHP method. From the result of the evaluation, the pred ominance of new loudspeaker systems which we developed is proved here.

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This papar analyzes the methods of compositions of Kahn's works in 1954-58 in comparison with his last architectural idea that is 'Room'. And it will be pointed out that the methods developed in 1954-58 are based on the ideas of 'Nature' and 'Room', but have their critical limitations on making the meanigful enclosures.

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A new magnetic circuit for a low distortion loudspeaker has been studied using a finite element analysis considering a minor hysteresis loop. The magnetic materials in the vicinity of the voice coil are magnetized by fields both AC currents and a permanent magnet. A minor hysteresis loop is induced by this magnetization. The incremental permeability of minor hysteresis loop effects on the sound distortion. We calculated the flux distribution of the magnetic circuit using a finite element method, considering the incremental permeability of the minor hysteresis loop obtained by an experimental method. It is clarified the relation between the sound distortion caused by the flux distribution and the magnetic structure. The developed magnetic circuit has a pole piece which has a hole at the upper surface and which is located higher than the plate.

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西表島の亜熱帯林において,つる植物ツルアダンの着生が土壌生態系に及ぼす影響を解明するため,琉球大学熱帯生物圏研究センター西表実験所において,林床堆積有機物量の測定,および,を用いた操作実験を行った.結果,ツルアダンが着生している樹木付近では,林床堆積有機物量が着生していない樹木付近の約1.5倍になることが分かった.また,この値に基づいた3処理(有機物なし,落葉落枝のみ,落葉落枝+ツルアダン)を施した実験を行った結果,落葉落枝+ツルアダン処理区において,スダジイの落葉の分解速度,および,落葉内窒素量の減少速度が他の処理区よりも有意に速くなった.さらに,土壌動物の合計個体数,および,アリの個体数は,落葉落枝>有機物なし≧落葉落枝+ツルアダンの順で,3処理間で有意に異なっていた.ただし,土壌微生物バイオマスNは,3処理間で違いは無かった.これらのことから,つる植物ツルアダンの着生は,ホスト樹木付近の林床堆積有機物量を変化させ,さらに,土壌動物相,落葉分解,および,窒素動態にも影響を及ぼすと考えられる.

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Development of elemental technology for gauging liquid fuel in a tank under microgravity condition will be required for developing fuel station in space and orbital transfer vehicle. A closed-type Helmholtz resonator had been already developed and worked well for this purpose. However, a microphone used for detecting acoustic response cannot work when it is masked by sloshing liquid, and might be damaged by its frequent contact with liquid. In order to resolve such a problem, a new measurement apparatus was developed without a microphone. The acoustic response was detected by measuring electrical impedance of loudspeaker's voicecoil. The performance of predicting liquid volume by using the electrical impedance method was comparable with the result of the microphone method. Some results of the ground test and the microgravity test with aircraft are summarized in the present report.

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スピーカの設計としては, できるだけ忠実に元の音場を再現するのは目標としている. 音を忠実に再現するためには, スピーカの物理特性と再生した音場との関係を解明することが重要である. スピーカに要求される物理特性の一つは, 周波数領域での平坦な音圧周波数応答特性をもつことである. そのため, スピーカの振動解析に関する多くの研究が行われているが, 空気の粘性が考慮されていないため、音圧周波数応答特性の推定精度が低下してしまう可能性がある. 笹島らはイヤホンの音響特性を解析する際に, 空気の粘性減衰を考慮することで精度向上に成功している. イヤホンよりサイズが大きいスピーカの場合でも, スピーカのボイスコイルと磁気回路の間の空間は非常に狭いことから, 空気の粘性減衰が大きく, 推定誤差の要因になる可能性が非常に高く, したがって, 一般的な音響解析では無視される空気の粘性による減衰効果がスピーカの解析精度に対する考慮する必要がある. 本報はコーンスピーカを対象に, 空気の粘性減衰の影響を考慮するため, 独自で振動と音響の連成解析ソフト開発した. 節点変位を共通な未知数として, 対象とする場合の要素に重ねあわせることにより, コーンスピーカの振動と音響の連成解析を行う. 本報では, まず, 振動特性及び音圧周波数応答特性について測定値と空気の粘性を考慮した解析値及び空気の粘性減衰を考慮しない解析値との比較を行う. コーンの振動変位の実測値と解析値がほぼ同じ特徴をもつ結果が得られた. また, スピーカの音圧周波数応答特性の変化と特徴についても従来の文献の見解と一致し, 空気の粘性を考慮した解析法は高い解析精度が得られた. 次に, 本解析法の精度を確認した上で, コーンスピーカの設計上重要と考えられるボイスコイル周りの空気の挙動を検討する. 空気の粘性を考慮した本解析法を用い, 変位を未知数として解くことにより, 空気の動きを確認することが可能となった. ボイスコイルと磁気回路の間にある狭い空間の粘性抵抗などを調整することによって, 意図的にスピーカの細かい特性が設計できる可能性を示している. 最後に, 今まで十分に解明されていないコーンとエッジがスピーカの振動特性に及ぼす影響について詳細な検討を行う。金属材料と紙系材料で作られたコーンの振動特性を解析し, 材料違いによるコーンの振動特性の影響が明らかになった. また, 柔らかい材料と硬い材料で作られたエッジの振動特性についても解析し, コーンの形状を変えずに, エッジの特性だけを変更させながら, 意図的にスピーカの最初のピーク位置など細かい特性をコントロールする可能性を示している. 今後の課題として, 実際のコーンスピーカだけではなく, 複雑な形状のスピーカの解析も検討したいと考えている. さらに, スピーカ部品の形状や材料の物性値を変えて, 音圧周波数応答特性の平坦化を実現するための最適化設計に検討して行く予定である.

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A Topology optimization attracts attention as a useful technique because of its flexibility in the design and applied to the various fields. To solve the wave problem with the impedance boundary condition, the utilization of the BEM and the level set method is proposed. The conventional method, however, cannot be applied to the acoustic problem dealing with plurality of fixed frequencies. In this paper, the topology optimization using the BEM and the level set method is applied to the design problem of an acoustic enclosure to improve the acoustic performance. The method for the acoustic problem dealing with plurality of fixed frequencies is proposed and some results are shown in this paper.

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In this study, we prepared a stage sound field using virtual sound source distribution and conducted examinations of the acoustic effects of initial reflected sound on the stage, from the side walls, ceiling and the audience area on subjective evaluations by solo performers under conditions of simulated stage sound field in which the direction, energy and arrival time of the initial reflected sound group surrounding the performer were systematically varied. As a result, we found that lateral reflected sound has the role of returning the primary sound to the performer on the stage and that reflected sound from the ceiling, which arrives slightly later than the lateral reflected sound, is linked to the quality of the response and is also a factor in "ease of performance". In addition, we also realized that the forward reflected sound from the audience area gives the performer the impression that the sounds of the performance are reaching the audience and that this impression is not only influenced by the volume of the reflected sound from the audience area but also the arrival time of the reflected sound.

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　　　It is generally recognized that commons have played a key role in English village life.Three types of rights ― such as ownership, common right and public rights of access ―overlap each other on the same lands. After the mid-nineteenth century a social movement led by the urban middle class has been developed claiming public rights of access to the common lands for air and exercise. This paper analyzes the historical process and the significance of the movement. The Commons Preservation Society (now The Open Spaces Society) has been tackling access issues persistently over a century. The Society aimed at not only the protection of common rights from enclosure but the opening of commons for the public enjoyment. The aim was partially realized after a series of Commons Acts in the late nineteenth and early twentieth century. The Metropolitan Commons Act 1866 was the first step in protecting urban commons from enclosure and claimed their preservation as open spaces. The Law of Property Act 1925 established the public rights of access to metropolitan commons for the first time. The Act strictly forbade owners to erect any building or fence whereby access was prevented or impeded.
　　　The public now have access rights to areas amounting to about 20 per cent of the whole common lands. The author regards it epoch-making that the general right of public access has been established on a wide range of open country in Britain. Through this process the legal structure of commons has changed its individual characteristic and accepted the concept of the right of access by public at large.

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Since the end of the nineteenth century a number of scholars have given their attention to the study of parliamentary enclosure. Books and Articles were published one after another, among which works of high quality appeared: those of W. HASBACH, E.C.K. GONNER, G.SLATER, A.H.JOHNSON, J.L.& B.HAMMOND, J.D.CHAMBETS. They chiefly dealt with such problems as the process of deliberation of enclosure bill, fairness of enclosure commissioners, cost and its financing, the relation between enclosure and labour supply in the Industrial Revolution. This paper, analysing enclosure documents owned by the Buckinghamshire County Record Office, attempts to clarify how landed property was distributed at enclosure of Weston Turville in Buckinghamshire, 1798-1800. It is a problem previous studies rather neglected. Comparing, especially, the landed property of each proprietor before and after enclosure is the main issue here. On the whole each property reduced by about twenty or thirty per cent after distribution. This is due to the commutation of tithes by enclosure act. Tithes were generally extinguished in exchage for allotments of land. Ecclesiastical estate was enlarged by nearly 300 acres in this parish; the rector became the second biggest landowner in the parish. Some irregular cases, however, are observed. Among about fifty proprietors in the parish, some reduced their property drastically and to some land was not alloted at all. They are thought to have sold a part or whole of their property. Instead, a dozen of new proprietors appeared after enclosure. Great consequence of tithe commutation, as many scholars have pointed out, is confirmed in this parish. How it relates to a tendency to land consolidation, however, we cannot exactly say unless we fruther observe the parish at several points after enclosure.

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The efficiency of pitfall traps was investigated using two size of enclosure (5 m×5 m and 10 m×10 m) in grassland under controlled population density of marked carabid beetles (Carabus insulicola insulicola Chaudoir, 1869) and different number of traps. Pitfall traps were evenly located in every enclosure. Checks on the pitfall traps were carried out every one or two hours on several days in July and August 2002. The efficiency of pitfall traps was correlated with the density of beetles, but not to the size of enclosure. In 5 m×5 m enclosure, the efficiency of individual pitfall traps was higher at about 2 m intervals of traps compared to 1 m, but the total number of caught beetles was higher at 1 m intervals than about 2 m. In this season this carabid beetle is nocturnal, but the activity of beetles was not steady. It increased rapidly from sunset to midnight and decreased by slow degrees from midnight to sunrise. It is thought that not all individual beetles were active each night, and that the activity patterns resulted from beetles reducing their activity according as individuals fed. From these results, a few points concerning the field research of this carabid beetle were suggested.

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　近年の東京湾では，外来性二枚貝のホンビノスガイが増えているが，生態系への影響はわかっていない。本研究では，

を使った野外操作実験を行い，ホンビノスガイが，砂質干潟で，底質環境，底生微細藻類およびベントス群集に与える影響を測定した。春のホンビノスガイは在来種アサリと比較して，その生物攪拌により底質の粒度と酸化還元電位を大きくし，さらに底生珪藻の現存量を増加させる生態系機能を有することがわかった。しかし，メイオベントスやマクロベントスの現存量や種組成への影響は見られなかった。

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