• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 12
  • 4
  • 2
  • 2
  • 2
  • Tagged with
  • 23
  • 23
  • 7
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

多項分配之分類方法比較與實證研究 / An empirical study of classification on multinomial data

高靖翔, Kao, Ching Hsiang Unknown Date (has links)
由於電腦科技的快速發展,網際網路(World Wide Web;簡稱WWW)使得資料共享及搜尋更為便利,其中的網路搜尋引擎(Search Engine)更是尋找資料的利器,最知名的「Google」公司就是藉由搜尋引擎而發跡。網頁搜尋多半依賴各網頁的特徵,像是熵(Entropy)即是最為常用的特徵指標,藉由使用者選取「關鍵字詞」,找出與使用者最相似的網頁,換言之,找出相似指標函數最高的網頁。藉由相似指標函數分類也常見於生物學及生態學,但多半會計算兩個社群間的相似性,再判定兩個社群是否相似,與搜尋引擎只計算單一社群的想法不同。 本文的目標在於研究若資料服從多項分配,特別是似幾何分配的多項分配(許多生態社群都滿足這個假設),單一社群的指標、兩個社群間的相似指標,何者會有較佳的分類正確性。本文考慮的指標包括單一社群的熵及Simpson指標、兩社群間的熵及相似指標(Yue and Clayton, 2005)、支持向量機(Support Vector Machine)、邏輯斯迴歸等方法,透過電腦模擬及交叉驗證(cross-validation)比較方法的優劣。本文發現單一社群熵指標之表現,在本文的模擬研究有不錯的分類結果,甚至普遍優於支持向量機,但單一社群熵指標分類法的結果並不穩定,為該分類方法之主要缺點。 / Since computer science had changed rapidly, the worldwide web made it much easier to share and receive the information. Search engines would be the ones to help us find the target information conveniently. The famous Google was also founded by the search engine. The searching process is always depends on the characteristics of the web pages, for example, entropy is one of the characteristics index. The target web pages could be found by combining the index with the keywords information given by user. Or in other words, it is to find out the web pages which are the most similar to the user’s demands. In biology and ecology, similarity index function is commonly used for classification problems. But in practice, the pairwise instead of single similarity would be obtained to check if two communities are similar or not. It is dislike the thinking of search engines. This research is to find out which has better classification result between single index and pairwise index for the data which is multinomial distributed, especially distributed like a geometry distribution. This data assumption is often satisfied in ecology area. The following classification methods would be considered into this research: single index including entropy and Simpson index, pairwise index including pairwise entropy and similarity index (Yue and Clayton, 2005), and also support vector machine and logistic regression. Computer simulations and cross validations would also be considered here. In this research, it is found that the single index, entropy, has good classification result than imagine. Sometime using entropy to classify would even better than using support vector machine with raw data. But using entropy to classify is not very robust, it is the one needed to be improved in future.
22

電腦輔助語言學習之研究-以我國學生學習日語為例 / A Study of Computer Aided Language Learning-Taiwan Students Learning Japanese as an Example

王珮姍, Wang, Pei Shan Unknown Date (has links)
本研究針對我國學生學習日語發音進行相似度指標發展之初探,貢獻為針對目前日語發音提供一個相似度的指標可以和老師語音進行比較分析,找出分析日語發音相似度之模式。 研究從聲音數位化的角度切入,有別於過去研究使用語音辨識的方式來進行,聲音數位化後為數值的方式,因此使用指標來計算相似的程度。研究提出一套對應的聲音相似度指標,以電腦分析輔助日語學習者的發音練習。 指標建立過程由聲音取樣、正規化、端點偵測,到實際的運算,使用所蒐集的聲音資料來測試指標的穩定度與有效性,研究結果說明在以日語為母語者間的指標都很靠近,而不同日語腔調間會有一定的指標差異,對於一定日語程度的對象而言,指標落點很靠近,惟本研究此次蒐集到的聲音資料,其應用指標運算結果的分佈太過集中,如果能有更多樣化的聲音資料來測試指標應能有較漂亮的分佈圖形。 / This research includes developing a similarity index applies to the evaluation of Taiwan students learning Japanese pronunciation. The contribution of this research is that it provides a similarity index to the Japanese pronunciation comparing to the teacher’s pronunciation, finding the model of how to analysis the similarity of Japanese pronunciation. This research uses the digital audio processing to begin with, which is different from the other research that uses the speech recognition to evaluate the pronunciation. The audio will turn into numerical format after digitalize, so this research uses an index to calculate the similarity. By using this similarity index, the computer can become an assistant role that helps to analysis while learning Japanese pronunciation. The developing of index starts from audio sampling, audio normalizing, and end-point detection to the calculation of similarity index. This research collects audio data to test the stability and the validity of the similarity index. The result indicates that the similarity index of native Japanese speakers is very close;and the similarity index contains certain difference between different accents. For those Taiwan students who qualify with Japanese, their similarity index is close. Nevertheless, the result of the similarity index is too centralized, it would be better if there are more audio data to test the similarity index.
23

Spatial ecology of marine top predators

Jones, Esther Lane January 2017 (has links)
Species distribution maps can provide important information to focus conservation efforts and enable spatial management of human activities. Two sympatric marine predators, grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina), have overlapping ranges but contrasting population dynamics around the UK; whilst grey seals have generally increased, harbour seals have shown significant regional declines. A robust analytical methodology was developed to produce maps of grey and harbour seal usage estimates with corresponding uncertainty, and scales of spatial partitioning between the species were found. Throughout their range, both grey and harbour seals spend the majority of their time within 50 km of the coast. The scalability of the analytical approach was enhanced and environmental information to enable spatial predictions was included. The resultant maps have been applied to inform consent and licensing of marine renewable developments of wind farms and tidal turbines. For harbour seals around Orkney, northern Scotland, distance from haul out, proportion of sand in seabed sediment, and annual mean power were important predictors of space-use. Utilising seal usage maps, a framework was produced to allow shipping noise, an important marine anthropogenic stressor, to be explicitly incorporated into spatial planning. Potentially sensitive areas were identified through quantifying risk of exposure of shipping traffic to marine species. Individual noise exposure was predicted with associated uncertainty in an area with varying rates of co-occurrence. Across the UK, spatial overlap was highest within 50 km of the coast, close to seal haul outs. Areas identified with high risk of exposure included 11 Special Areas of Conservation (from a possible 25). Risk to harbour seal populations was highest, affecting half of all SACs associated with the species. For 20 of 28 animals in the acoustic exposure study, 95% CI for M-weighted cumulative Sound Exposure Levels had upper bounds above levels known to induce Temporary Threshold Shift. Predictions of broadband received sound pressure levels were underestimated on average by 0.7 dB re 1μPa (± 3.3). An analytical methodology was derived to allow ecological maps to be quantitatively compared. The Structural Similarity (SSIM) index was enhanced to incorporate uncertainty from underlying spatial models, and a software algorithm was developed to correct for internal edge effects so that loss of spatial information from the map comparison was limited. The application of the approach was demonstrated using a case study of sperm whales (Physeter macrocephalus, Linneaus 1758) in the Mediterranean Sea to identify areas where local-scale differences in space-use between groups and singleton whales occurred. SSIM is applicable to a broad range of spatial ecological data, providing a novel tool for map comparison.

Page generated in 0.0511 seconds