Basalt prism of Santa Maria Regla river, Huasca, Mexico
The purpose: To study the basaltic prisms to understand their formation. Tasks: To study chemical and mineral composition, textures and density of basalts of central and peripheral parts of prisms, to reveal the possible difference as a consequence of the formation of Benard sells. Basalt prisms have 6-5-4-face shape with a diameter 10 -50 cm and height of 30-40m. They are divided by transverse fracture in blocks of 20-50 cm. Prismatic jointing of basalts widespread throughout the world. There are many theories about its origin. We decided to collect data to identify the most appropriate of these. We suppose that if the hypothesis about the role of Benard cells is correct then the properties of basalt in the central and peripheral parts of the prisms must be different. If we consider the center of the prism as the center of the cell, where the hot matter rise, spreading out to the periphery and lower in the peripheral part, it is likely that the density of basalt forming in the center must be lower than at the periphery and later crystallization should lead to a slightly more acidic basalt in the middle. We determined the density of basalts of different parts of prisms. And the density of central part basalts was equal to 2.502g/sm3 and of peripheral part basalts was equal to 2.907g/sm3. X-ray fluorescence analysis showed that basalt of central part contain 12,91% Si and of peripheral part only 10,17%. Basalt of central part is depleted of Fe, Mn, Ti, Mg compared with of peripheral. We investigated samples and thin sections of basalts under the microscope MIN-8. For basalts of peripheral part flow texture expressed by the orientation of the microlites are characteristic. In the central part flow texture are poorly expressed but we can see many phenocrysts. Our data reveal a significant and expected difference between the basalts of central and peripheral parts of prism, that are the evidences in favor of the hypothesis about the role of Benard cells in the formation of basalt prismatic jointing.
阿里巴巴轉盤問題
本作品為環球數學城市競賽的考題之推廣( International Mathematics Tournament of the Towns, Senior A-Level Paper, Fall 2009, No. 7 ),然而此題目本身比較接近Scientific American ( Feb 1979 )中 Martin Gardner 的文章 The Rotating Table 所提出的問題。 而此問題的多邊形版已被數學家解決(Ted Lewis & Stephen Willard, 1980, The Rotating Table,Mathematics Magazine, 53,Page 174-175.)。然而此份作品採用簡潔的初等數學歸納法證明了原本的多邊形情形,且專注於探討條件改變為m=n-1時的多邊形情形。 m=n-1時的情形是前人所沒有做出結果的,且m=n-1的情形遠遠比m=n 的情況來得複雜多變,其中估計上下界所使用的許多組合技巧相當特別。然而其中當n為3 和5的倍數時有比較特殊的情況,這一個部分僅能給出目前得出的k值上界。而其他情況則能夠找出所有的k值。
A Backpropagation Neural Network Model on Precipitation Forecasting in the Philippines
Backpropagation neural networks were used to forecast daily rainfall with minimal error for Metro Manila in order to have an inexpensive way of accurately predicting weather. Calamities brought on by heavy rainfall have caused great economic, infrastructure and human loses. Neural networks have the ability to discern complex patterns in noisy data; this makes it a viable method for weather forecasting. Daily precipitation, humidity, rain indication, sea level pressure, temperature and maximum sustained wind speed for January 2000 to December 2010 were acquired from the Philippine Atmospheric Geophysical and Astrological Services Administration. The neural network made use of Python 2.7.2 and the backpropagation program by Neil Schemenauer (python.org). It considered different neural network architectures with a total of 2844 data sets for training and 708 data sets for testing. Each neural network’s accuracy was measured with a graph of the actual and predicted values, correlation coefficient, and root mean square error. It was observed that the neural network with architecture 5-8-1 yielded the most accurate results as it had the highest correlation coefficient of 0.48599 and smallest root mean square error of 14.84. It was also observed that the trends of the predicted values followed that of the target values. This suggests that it is possible to create a neural network with a moderate correlation given daily weather data. It is recommended that further researches make use of hourly data instead of daily data for more accurate results. Other variables, which might affect rainfall, not in this study should also be considered. This research could aid in the anticipation of calamities and the decision making involved in shipping, fishing and aviation industries.