Volatility of commodity prices has affected dramatically the coffee industry in recent years, particularly small holder farmers. Differentiation of coffee through certification, such as sustainahility and quality attr...Volatility of commodity prices has affected dramatically the coffee industry in recent years, particularly small holder farmers. Differentiation of coffee through certification, such as sustainahility and quality attributes, has been proposed as a strategy for protection of the farmers against volatility in the international prices. This research paper evaluated three different models to explore the effectiveness of the differentiation strategies in protecting the farmer against price volatility in recent years, focusing on the case of Costa Rica. Evidence showed important differences in the price dynamics over time when comparing three groups of coffee.展开更多
Based on discrete wavelet transform, both relative wavelet energy （RWE） and segment wavelet entropy （SWE） of electroencephalogram （EEG） are defined in this paper. The RWE provides quantitatively the information ...Based on discrete wavelet transform, both relative wavelet energy （RWE） and segment wavelet entropy （SWE） of electroencephalogram （EEG） are defined in this paper. The RWE provides quantitatively the information about the relative energy associated with different frequency bands present in the EEG. The SWE carries information about the degree of order or disorder associated with different time segment of EEG evolution, which can determine the time-segment loealizations of abnormal dynamic processes of brain activity due to the localization characteristics of the wavelet transform. The experimental results show that the RWE and SWE are different between epileptic EEGs and normal EEGs, which demonstrate that the RWE and the SWE are helpful to analyze the dynamic behavior of different EEGs.展开更多
文摘Volatility of commodity prices has affected dramatically the coffee industry in recent years, particularly small holder farmers. Differentiation of coffee through certification, such as sustainahility and quality attributes, has been proposed as a strategy for protection of the farmers against volatility in the international prices. This research paper evaluated three different models to explore the effectiveness of the differentiation strategies in protecting the farmer against price volatility in recent years, focusing on the case of Costa Rica. Evidence showed important differences in the price dynamics over time when comparing three groups of coffee.
基金GNatural Science Foundatoin of Fujian Province of China grant number: 2010J01210 and T0750008
文摘Based on discrete wavelet transform, both relative wavelet energy （RWE） and segment wavelet entropy （SWE） of electroencephalogram （EEG） are defined in this paper. The RWE provides quantitatively the information about the relative energy associated with different frequency bands present in the EEG. The SWE carries information about the degree of order or disorder associated with different time segment of EEG evolution, which can determine the time-segment loealizations of abnormal dynamic processes of brain activity due to the localization characteristics of the wavelet transform. The experimental results show that the RWE and SWE are different between epileptic EEGs and normal EEGs, which demonstrate that the RWE and the SWE are helpful to analyze the dynamic behavior of different EEGs.
