Natural frequencies and damping ratios of Norway spruce (Picea abies (L.) Karst) growing on subalpine forested slopes

Jonsson, M. J.; Foetzki, Andrea; Kalberer, M.; Lundström, Tor; Ammann, Walter; Stöckli, Veronika

doi:10.1007/s00468-007-0147-x

Cited by 38 publications

(35 citation statements)

References 15 publications

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“…(13), ω sb = 1.48 rad s −1 (0.24 Hz), see Table 2. This value is in very good agreement with the measurements (see Jonsson et al, 2007). The modulus of elasticity was set to E = 10 GPa based on experimental measurements (Haines et al, 1996).…”

Section: Applicationsupporting

confidence: 66%

Dynamic magnification factors for tree blow-down by powder snow avalanche air blasts

Bartelt

Bebi

Feistl

et al. 2018

Nat. Hazards Earth Syst. Sci.

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Abstract. We study how short duration powder avalanche blasts can break and overturn tall trees. Tree blow-down is often used to back-calculate avalanche pressure and therefore constrain avalanche flow velocity and motion. We find that tall trees are susceptible to avalanche air blasts because the duration of the air blast is near to the period of vibration of tall trees, both in bending and root-plate overturning. Dynamic magnification factors for bending and overturning failures should therefore be considered when back-calculating avalanche impact pressures.

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Section: Applicationsupporting

confidence: 66%

Dynamic magnification factors for tree blow-down by powder snow avalanche air blasts

Bartelt

Bebi

Feistl

et al. 2018

Nat. Hazards Earth Syst. Sci.

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“…Wind speed can cause varying levels of streamlining in a tree (Vogel, 1989), and that altering of architecture could lead to variation in FVF. However, FVF does not appear to be influenced by direction of the force on a tree (Jonsson et al, 2007;Kane et al 2014).…”

Section: Drivers Of Fundamental Vibrational Frequencymentioning

confidence: 84%

“…The vast majority of studies on the effects of wind on trees have been conducted with even-aged, monospecific coniferous plantations (see Milne, 1991;Gardiner, 1995;Gardiner et al, 1997;Moore, 2000;Moore & Maguire, 2004Jonsson et al 2007). The preponderance of these studies induced tree sway by mechanical means (winching and releasing the tree trunks), for example in Norway spruce (Jonsson et al 2007), Sitka spruce (Milne, 1991) and Monterey pine (Moore, 2000). Far fewer studies have been conducted on temperate deciduous tree species, and by and large have also used mechanically-induced treatments to simulate the effect of wind on trees (see Kane et al 2014, for example with Acer saccharum; Roodbaraky et al, 1994 with Platanus).…”

Section: Drivers Of Fundamental Vibrational Frequencymentioning

confidence: 99%

Determinants of tree sway frequency in temperate deciduous forests of the Northeast United States

Bunce

Volin

Miller

et al. 2019

Agricultural and Forest Meteorology

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“…Linear Variable Displacement Transducers (LVDT) (Aristizábal, Oliveros, & Alvarez, 2003); accelerometers (Jonsson et al, 2007;Amirante, Catalano, Giametta, Leone, & Montel, 2007) and strain gages (James, Haritos, & Ades, 2006) are frequently used to measure vibration in plants. Obtaining the response of the coffee fruitstem system to vibration, using direct contact sensors and transducers, is hindered by physical and mechanical limitations.…”

Section: Introductionmentioning

confidence: 99%

<b>Determination of modal properties of the coffee fruit-stem system using high speed digital video and digital image processing

et al. 2016

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ABSTRACT. Detachment of coffee fruit is usually accomplished by means of mechanical impacts and vibrations applied to the plant. Modal properties of the coffee fruit-stem system represent important information for efficient and selective harvesting. This study aimed to determine the modal parameters of the coffee fruit-stem system, such as natural frequency and damping coefficient, using high speed digital videos. With image processing techniques, it was obtained the resulting displacement of the system subjected to an impulse. The modal parameters were determined by the logarithmic decrement method, considering the system as underdamped. The use of high-speed video and digital image processing techniques allowed the simple and reliable determination of modal parameters of the coffee fruit-stem system. Natural frequencies for the coffee fruit-stem system were 11.62 and 13.29 Hz; the damping coefficient was 0.0253 and 0.029 N s m -1, and the equivalent stiffness was 8.61 and 7.09 N m -1 for red and green ripening stages, respectively. It was found overlap of resonance bands, between the ripening stages red and green, hindering the selective mechanical detachment in the first natural frequency range of the coffee fruit-stem system. Keywords: image segmentation, mechanical harvesting, mechanical vibrations.Determinação das propriedades modais do sistema fruto-pedúnculo do café por vídeos de alta velocidade e processamento de imagens digitais RESUMO. A derriça dos frutos do cafeeiro é comumente realizada por meio de impactos e vibrações mecânicas aplicadas à planta. Propriedades modais do sistema fruto-pedúnculo do café são informações importantes para uma derriça eficiente e seletiva. Objetivou-se determinar os parâmetros modais do sistema fruto-pedúnculo do café, tais como frequência natural e coeficiente de amortecimento, empregando-se vídeos digitais de alta velocidade. Por meio de técnicas de processamento de imagens foi obtido o deslocamento resultante do sistema submetido a um impulso. A partir do método do decremento logarítmico foram obtidos os parâmetros modais, idealizando o sistema como subamortecido. A utilização de vídeos de alta velocidade e técnicas de processamento de imagens digitais permitiu a determinação dos parâmetros modais do sistema fruto-pedúnculo do café de forma simples e confiável. As frequências naturais do sistema foram de 11,62 e 13,29 Hz; os coeficientes de amortecimento foi de 0,029 e 0,0253 N s m -1 e a rigidez equivalente foi de 8,61 e 7,09 N m -1 para os estádios de maturação cereja e verde, respectivamente. Houve sobreposição de faixas de ressonância entre os estádios de maturação cereja e verde, dificultando a derriça mecânica seletiva do café na faixa da primeira frequência natural.Palavras-chave: segmentação de imagem, colheita mecanizada, vibrações mecânicas.

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Natural frequencies and damping ratios of Norway spruce (Picea abies (L.) Karst) growing on subalpine forested slopes

Cited by 38 publications

References 15 publications

Dynamic magnification factors for tree blow-down by powder snow avalanche air blasts

Dynamic magnification factors for tree blow-down by powder snow avalanche air blasts

Determinants of tree sway frequency in temperate deciduous forests of the Northeast United States

<b>Determination of modal properties of the coffee fruit-stem system using high speed digital video and digital image processing

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