Cellular automata model for size segregation of particles

金沢大学理工研究域機械工学系This paper deals with the study of size segregation of particles where the size difference causes characteristic movement of particles inside granular media according to the induced vibration. In this study, segregation of particles due to the difference in size is simulated using Cellular Automata. A connected lattice automaton is introduced in the model, so that the variation of particle sizes as well as geometrical arrangement between particles can be represented. The Cellular Automata model can produce various characteristics which are observed in the actual granular systems. Furthermore, it is known from both numerical and experimental observations that the segregation progress is dependent on the amplitude of excitation as well as the particle size ratio. © 2010 Springer-Verlag

Study on acoustic field with fractal boundary using cellular automata

金沢大学理工研究域機械工学系In the present study, characteristics of the acoustic field in an enclosure bounded by fractal walls are investigated using Cellular Automata (CA). CA is a discrete system which consists of finite state variables arranged on uniform grid. The dynamics of CA is expressed by temporary updating the states of cells according to the local interaction rules, defined among a cell and its neighbors. In this paper, the effect of fractal shaped boundary structure to the reverberation and sound absorption characteristics of an enclosure is investigated for two dimensional acoustic wave propagation model described by CA. Local rules are provided for the construction of fractal patterns as well as representation of wave propagation phenomena. It is known by the numerical simulations that the damping enhancement and also frequency-selective absorbing behavior is seen for specific fractal patterns and stage numbers. © 2008 Springer-Verlag Berlin Heidelberg

A combined approach for modeling particle behavior in granular impact damper using discrete element method and cellular automata

A particle impact damper is a vibration absorber type that consists of a container attached to a primary vibrating structure. It also contains many particles that are constrained to move inside the container, whereby the damping effect can be obtained by collision between particles and the container. The discrete element method (DEM) has been developed for modeling granular systems, where the kinematics of each particle are calculated numerically using the equations of motion. However, the computational time is significant since the algorithm checks for particle contacts for all possible particle combinations. The use of a cellular automata (CA) modeling technique may provide increased computational efficiency due to the local updating of variables, and the discrete treatment of time and space. In this study, we propose a new approach combining DEM with CA for modeling a granular damper under a forced excitation. We use DEM to describe the particle motion according to the equations of motion, while CA is introduced for the particle contact checks in discrete space. We also investigate the effect of simplification in the contact force model, which allows the unit time step of numerical integration to become larger than that used in the strict model. It is shown that the suggested particle contact scanning method and the force approximation model contribute to the reduction of the computational time, and neither degenerates the calculation accuracy nor causes the numerical instability. © 2016 Springer Science+Business Media DordrechtEmbargo Period 12 month

Modeling of sound absorption by porous materials using cellular automata

金沢大学大学院自然科学研究科知的システム創成金沢大学工学部In the present study, acoustic wave propagation in acoustic tube in-corporating sound absorbing material is simulated using Cellular Automata (CA). CA is a discrete system which consists of finite state variables, arranged on a uniform grid (cell). CA dynamics is described by a local interaction rule, which is used for computation of new state of each cell from the present state at every time step. In this study an acoustic tube model is introduced in which ab-sorbing material is characterized by direct modeling of porosity and flow resis-tance. Direct numerical simulation CA model is performed and evaluated by absorption coefficient using standing wave ratio measure. The results showed good correspondence with analytical solutions. © Springer-Verlag Berlin Heidelberg 2006

Modelling of incident sound wave propagation around sound barriers using cellular automata

In the present study, acoustic wave propagation in the field including sound isolation panel is simulated using Cellular Automata (CA). CA is a discrete system which consists of finite state variables, arranged on a uniform grid. CA dynamics is described by a local interaction rule which is used for computation of new state of each cell from the present state at every time step. In this study a sound field is modeled using CA where the sound isolation panel exists and the numerical simulation results are evaluated quantitatively by the insertion loss. The results showed good correspondence with analytical solutions. © 2012 Springer-Verlag Berlin Heidelberg

Approach for combining physical properties and sensibility for pleasant beverage can-opening sound

The sound quality of consumer products has recently become an important feature, receiving much attention in the fields of engineering and manufacturing. The sound could add value to the product in the way that it meets the interests and preferences of consumers in a wide range of fields. The present study deals with the sound emitted from beverage cans when lifting the tab of the can end to open it before drinking. With a view toward finding the characteristics of sound that have a sense of ease and certainty for the consumer when opening a beverage can, we introduce the semantic differential method for the subjective assessment of sounds of various cans. We then perform waveform analyses in both time and frequency domains to determine the physical properties of the desirable sounds. Finally, we successfully correlate the texture factor with the duration of the tearing sound, which may be a new way to design cans with pleasant sounds. © 2015 Elsevier Ltd. All rights reserved

Experimental Investigation of an Adaptively Tuned Dynamic Absorber Incorporating Magnetorheological Elastomer with Self-Sensing Property

The magnetorheological elastomer (MRE) is known to belong to a class of smart materials whose elastic properties can be varied by an externally applied magnetic field. In addition to the property of the field-dependent stiffness change of the MRE, the electrical resistance of the composite is also changed by the induced strain, thereby providing a new self-sensing feature. In the present study, a novel, dynamic vibration absorber is developed using an MRE with a self-sensing function and adaptability. The natural frequency of the absorber is instantaneously tuned to a dominant frequency extracted from the strain signal of MRE. The damping performance test shows that the vibration of a system with one degree-of-freedom that is exposed to a nonstationary disturbance can be adequately reduced by the proposed frequency-tunable dynamic absorber without the use of external sensors. © 2016 Society for Experimental MechanicsIn Press / Embargo Period 12 month

ハイブリッド型吸音パネルに関する研究

金沢大学理工研究域薄板型の吸音パネルは一般に背後に空気層を設け,パネルに作用する音響エネルギーを振動に変換することによりエネルギーを消費する受動型の吸音装置として用いられるが,その受動的吸音効果について評価するために,箱型閉空間の壁面の一部に弾性パネルの埋め込まれたモデルを考え,パネルの振動放射音を考慮した室内音場に関する数値計算モデルを構築した.弾性平板以外の壁面は剛壁とし,室内フロアに点音源が一つあるものとする.その結果,支持条件によって決まるパネルの固有振動数付近では吸音効果は低下するが,それ以外の周波数に対しては数dB程度の吸音効果があることを確認した.また,音源周波数が室内の共鳴周波数付近の場合,音圧のモード節が平板上にない条件において,若干の吸音効果が見られた.さらに,吸音性能の向上と適用周波数範囲の拡大を目的として,受動要素としての吸音パネルにアクティブ制御手法を付加することによるハイブリッド化について検討した.パネルに圧電素子を貼り付けることによりパネルの振動を励起・制御するものとし,圧電素子の特性を考慮した弾性平板の振動について数値計算モデルの定式化を行った.制御系としては,音源の多様性や構造物の動特性変化を考慮してニューラルネットワークを採用した.音源より単一周波数の正弦波を出力し,いくつかの周波数について室内音響制御シミュレーションを行った.その結果,対象とする周波数および音圧評価点の選択によっては受動的効果のみの場合と比較してさらに音圧を低減することが可能であるが,受動的効果について検討した場合と同様,パネルの振動モードおよび室内音場のモードに関連して,十分な抑制が出来ない場合があることがわかった.研究課題/領域番号:12750182, 研究期間(年度):2000-2001出典：「ハイブリッド型吸音パネルに関する研究」研究成果報告書　課題番号 12750182（KAKEN：科学研究費助成事業データベース（国立情報学研究所））（https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-12750182/)を加工して作

創発的手法による振動・音響系のモデル化と制御に関する研究

取得学位：博士(工学)，学位授与番号：博乙第275号，学位授与年月日：平成16年3月25日,学位授与年：200

生理的振戦を対象としたウェアラブル振動制御デバイスの開発

金沢大学理工研究域フロンティア工学系生体の手指に現れる振戦を抑制するために,ばねと質量で構成される動吸振器を製作し,その制振,効果について検討した.生理的振戦の主要周波数である9Hz前後で固有振動数の調整が可能なように製作し,個人差によるずれを調整可能とするためばね定数をねじで可変とする機構を設けた.また,動吸振器に適度な減衰を与えることで制振効果を向上させることができると考え,調整可能な減衰機構を付与した.動吸振器の寸法は極力小さく質量は約40g,縦20mm×横17mm×高さ16mmのブロック形状とし,腕時計のように装着可能とした.振戦制御の対象となる被験者の姿勢は肘を水平に伸ばした状態に保ち,地面に対して水平方向の振動を計測した.また,生理的振戦は任意に発生・再現が困難なため擬似的に震えの状態を再現するべく,被験者の腕に加振装置を装着し,強制的に振動させた.動吸振器を装着する部位は手首上部とした.制振効果の評価方法としては,加速度計を人差し指先端に取り付け,水平方向の加速度の大きさを一定時間計測するとともに,紙上に描かれた直径120mmの実線円周上を被験者がペンでなぞり,基準線からのずれ量で評価を行った.本実験より,加速度についてはそのレベルが1/5程度まで低減され,さらに減衰比0.1程度まで動吸振器の減衰を大きく設定することで1/8程度まで制振効果が向上することが明らかとなった.また,基準線をなぞる試験についても同様に,動吸振器非装着時と比較して筆跡に見られる細かい振動的波形が除去されていることが確認でき,本装置により有効に振戦が抑制されることがわかった.一方で,本来,生理的振戦が自励的に発生する振るえであることを考慮して,前腕部に動吸振器が取り付けた状態を模擬した数値モデルを構築し,自励振動が発生する場合における動吸振器の制振効果について数値的な検討を行った.その結果,振戦発生機構の本質的な違いはあるものの,実験と同程度に動吸振器付加による制振効果を確認することができた.研究課題/領域番号:15760150, 研究期間(年度):2003 – 2004出典：「生理的振戦を対象としたウェアラブル振動制御デバイスの開発」研究成果報告書　課題番号15760150（KAKEN：科学研究費助成事業データベース（国立情報学研究所））（https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-15760150/)を加工して作