都市內的樹木傾倒會造成居民與財產損害，其中風災是造成樹木傾倒的主因，若能預測樹木在風災中的傾斜情況並進行適當處理，將可有效的降低損害。本論文著重於研發樹木在風壓負荷下所造成傾斜角度的預測技術。我們首先測量實際風壓負荷下的樹木傾斜加速度。接著，透過將加速度資料換為球座標系獲得樹木的傾斜角度與方向。然後，配合氣象站的風速和風向資料，根據樹木擺動的特性，取得風速與相對應的傾斜角度的資訊。隨後，根據此資訊，建立一個決策樹非線性迴歸模型，來預測在各風向的不同風速下樹木的傾斜角度。最後，我們以實際量測資料驗證此預測模型。實驗結果顯示所開發的預測模型在預測傾斜角度的準確率上有良好的效果，並獲得對將來的研究方向與系統實作有助的資訊。

Tilting or rotation of trees in the city will cause damage to residents and property, the main cause of the tilting or rotation of trees was wind disaster. If we can predict the tilting of trees in the wind disaster and carry out appropriate treatment, it will effectively reduce the damage. This paper focuses on the development of technology for predicting the tilting angle of trees under wind load. We first measure the tree's tilting acceleration under actual wind load. Next, the angle and direction of the trees are obtained by converting acceleration data into a sphere coordinate system. Then, according to the wind speed and wind direction information of the weather station, the wind speed and the corresponding tilting angle information are obtained based on the characteristics of the tree oscillation. Subsequently, based on this information, a non-linear regression model of the decision tree was established to predict the tilting angle of the trees at different wind speeds in different directions. Finally, we validate this prediction model with actual measurement data. The experimental results show that the developed predictive model has a good performance in predicting the accuracy of the tilting angle and obtains information that will help future research directions and system implementation.

參考文獻
[1] Kenneth R. James, Nicholas Haritos, Peter K. Ades, “Mechanical stability of trees under dynamic loads.”, American journal of Botany, 27 July 2006, 93(10): pp.1522-1530.
[2] A. Lopes, S. Oliveira, M. Fragoso, J.A. Andrade and P. Pedro, “Wind Risk Assessment in Urban Environments: The Case of Falling Trees During Windstorm Events in Lisbon.”, Bioclimatology and Natural Hazards, 2009, pp.55-74.
[3] Michael J.Mortimera and BrianKanea, “Hazard tree liability in the United States: Uncertain risks for owners and professionals.”, Urban Forestry & Urban Greening, Volume 2, Issue 3, 4 Nov. 2004, pp.159-165.
[4] António Saraiva Lopes, Flávio Mendes, Ezequiel Correia, “Street trees vulnerability to strong wind events in Lisbon: meteorological and phytosanitary assessment to mitigate urban hazards.”, International Conference on Urban Risks, Lisboa, June, 2016.
[5] H.Rahardjo, F.R.Harnas, I.G.B.Indrawan, E.C.Leong, P.Y.Tan, Y.K.Fong, L.F.Ow, “Understanding the stability of Samanea saman trees through tree pulling, analytical calculations and numerical models.”, Urban Forestry & Urban Greening, Volume 13, Issue 2, 30 Dec. 2013, pp.355-364.
[6] Jinxin Cao, Yukio Tamura and Akihito Yoshida,”Wind tunnel study on aerodynamic characteristics of shrubby specimens of three tree species.”, Urban Forestry & Urban Greening, Volume 11, Issue 4, 27 Jun. 2012, pp.456-476.
[7] Brian Kane, Yahya Modarres-Sadeghi, Kenneth R. James, Mark Reiland, “Effects of crown structure on the sway characteristics of large decurrent trees”, Trees, Vol. 28, Issue 1, Feb. 2014, pp 151–159.
[8] Kenneth R. James, Brian Kane, "Precision digital instruments to measure dynamic wind loads on trees during storms", Agricultural and forest meteorology, Vol. 148, Issues 6–7, 30 June 2008, pp..1055-1061.
[9] Ken James, Craig Hallam and Chris Spencer, “Tree stability in winds: Measurements of root plate tilt.”, Biosystems engineering, July 2013, 115.3, pp.324-331.
[10] Jeffery B. Cannon , Meredith E. Barrett and Chris J. Peterson , “The effect of species, size, failure mode, and fire-scarring on tree stability.”, Forest Ecology and Management, Volume 356, 15 Nov. 2015, pp. 196-203.
[11] K R. James, N Haritos, “Branches and damping on trees in winds”, Australasian Conference on the Mechanics of Structures and Materials, Byron Bay, 9-12 Dec.2014, pp.1011-1016.
[12] M. P. COUTTS, “Components of Tree Stability in Sitka Spruce on Peaty Gley Soil.”, Forestry: An International Journal of Forest Research, Volume 59, Issue 2, 1 Jan. 1986, pp. 173-197.
[13] T. Lundström, M. J. Jonsson M. and Kalberer, “The root–soil system of Norway spruce subjected to turning moment: resistance as a function of rotation.”, Plant and Soil, Volume 300, Issue 1–2, November 2007.
[14] Schwarz, M., D. Cohen, and Dani Or. "Pullout tests of root analogs and natural root bundles in soil: Experiments and modeling.", Journal of Geophysical Research: Earth Surface, Volume 116, Issue F2,22 Apr. 2011.
[15] Ken James, Craig Hallam and Chris Spencer, “Measuring tilt of tree structural root zones under static and wind loading”, Agricultural and forest meteorology, 15 Jan. 2013, 168: pp.160-167.
[16] Giambastiani, Y., Preti, F., Errico, A., & Sani, L., “On the tree stability: pulling tests and modelling to assess the root anchorage.”, International Symposium on Soil and Water Bioengineering in a Changing Climate, Glasgow, Scotland, UK, Sep. 2017.
[17] William G. Jacoby, “Loess: a nonparametric, graphical tool for depicting relationships between variables.”, Electoral Studies, Volume 19, Issue 4, Dec. 2000, pp. 577-613.