Increasing Weak Classifier Diversity in Ensemble Models by Feature Graphs

Jedním z běžných problémů strojového učení na datech genové exprese je nedostatek vzorků --- tyto datasety mají obvykle několik desítek tisíc atributů ale v nejlepším případě jen několik desítek vzorků, navíc, vzorky získané pomocí technologie microarray obsahují velké množství šumu. Z těchto důvodu modely postavené výhradně z naměřených dat obvykle trpí přeučením. Jednou možnou metodou řešící problém přeučení je použití apriorní znalosti k regularizaci. Tato práce analyzuje metodu network-constrained forest (NCF) navrženou Andělem a Klémou a dále předkládá zobecnění této metody používající jiné typy slabých klasifikátorů. Navržená metode je analyzována z pohledu diverzity a přesnosti na několika datasetech. Navíc, tato práce empiricky testuje teoretickou konvergenci NCF pro zvyšující se délky náhodné procházky použíté pro vzorkování atributů.One of the common problems in machine learning from gene expression data is the scarcity of samples --- these datasets usually have around tens of thousands of features but only several dozens of samples at best. Moreover, samples obtained using microarray technology are often very noisy. Therefore models built solely from measured data often suffer from overfitting. One of possible methods dealing with overfitting is to use prior knowledge for regularization. This work analyzes network-constrained forest (NCF) method proposed by Anděl and Kléma and proposes generalization of this method using other types of weak classifiers. The proposed method is analysed in terms of diversity and accuracy over several datasets. Moreover, this work empirically tests proposed convergence of NCF for increasing length of random walk used for feature sampling

Development of coatings for gas turbines burning biomass and waste-fuels

Worldwide, carbon dioxide emission reductions are in progress following the Kyoto Protocol implementation programme to mitigate climate change. More stringent reductions are expected to follow the present programme which ends in 2012. In addition to reducing carbon dioxide emissions, the major climate change mitigation policy is the elimination of waste. This project addresses both aspects, by facilitating the use of biomass and waste fuels in the gas turbines of highly efficient, integrated gasification combined cycle electricity generating units. Gases from the gasification of these fuels contain potentially damaging contaminants which, when combusted in gas turbines, will initiate hot corrosion. To resist hot corrosion, but still maximise gas turbine efficiency, the hot components of gas turbines require protective coatings. Five activities in this project required original research to meet the objectives. Firstly, to identify potentially damaging species in gasifier gases, which could remain after hot gas cleaning and, following combustion, initiate hot corrosion along the gas path of the gas turbine. Thermodynamic assessments, using MTDATA software, identified cadmium and lead species that could initiate hot corrosion in the gas turbine. The second research activity, involved Type II hot corrosion tests of the identified species on superalloys and typical commercial coatings. These tests simulated the same corrosion environment as in industrial high temperature gas turbine operation. Test results confirmed the thermodynamic assessments, with hot corrosion being initiated on all items tested, and was worse with lead and/or cadmium additions. The third research activity was to develop novel hot corrosion protective coatings. The approach was to develop the most economic coatings, which would provide comparable, or superior, hot corrosion performance to that provided by well proven commercial coatings already used with fossil fuel firing. From previous research at Cranfield, published literature, and after aluminising and silicon modified aluminising CVD trials, single-step silicon modified aluminising was adopted as the basis for novel coating development. The fourth research activity consisted of cyclic oxidation tests and, type II and type I hot corrosion tests, to assess the oxidation and hot corrosion protection provided by the novel coatings on IN738LC and CMSX-4 substrates. Cyclic oxidation tests at 950C and 1050C showed the novel coatings produced by CVD, at a soak temperature of 1050C and soak period of one hour, were superior for both substrates. Microstructurally, TCP phases were formed in CMSX-4 samples which could reduce mechanical strength in service. The TCP phases were observed in the high silicon containing coatings through a reaction with refractory metals diffusing outward from the CMSX-4. This was most noticeable in samples cyclically oxidised at 1050C for long times. Results of hot corrosion tests undertaken at 700C (type II) and 900C (type I) showed novel coatings on IN738LC samples to be more resistant than commercial coatings. Those on CMSX-4 samples had similar hot corrosion resistance to commercial coatings. The novel coatings provided high levels of hot corrosion resistance, which could be enhanced by improvements in deposition. The fifth research activity was to carry out EB-PVD TBC trials on an IN738LC turbine blade, which demonstrated that the novel coating provided an effective bond for the TBC. It is concluded that the novel, single-step silicon-aluminide coatings developed in this project, with identified improvements in quality, will provide effective hot corrosion resistance for gas turbines burning gasified biomass and waste fuels.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Comparative analysis of the technical and tactical activities of the best table tennis players in the world

У истраживању, које је имало карактер опсервационе, експлоративне еx post facto студије, испитивана је структура простора у којем се манифестује техничко- тактичка активност врхунских играча стоног тениса (играчи н=77; игралице н=77), учесника завршног олимпијског турнира, на одиграним мечевима (играчи н=154; игралице н=154), односно на 820 одиграних сетова (играчи н=423; игралице н=397). Сваки од играча је био описан преко 9 варијабли, а техничко-тактичка активност у мечевима и сетовима била је описана преко 17 варијабли. За основне циљеве студије постављено је утврђивање и поређење структура простора техничко-тактичких активности играча и дефинисање изабраних релевантних моделских карактеристика најбољих такмичара и такмичарки света. Добијени резултати дозвољавају да се закључи како се на основу техничко-тактичке активности врхунских играча и играчица стоног тениса у условима такмичења са равноправним противницима, обезбеђује валидан увид у структуру базичног техничко- тактичког простора, којег описују 9 интерпретабилних латентних димнзија. Структуре простора у популацијама мушкараца и жена се квалитативно нису разликовале. Испитивање утицаја избора доминантне руке на ефикасност извођења техничко- тактичких елемената и успешност, указује на значајне предности леворуких, како играча, тако и играчица. Повезаност показатеља морфолошког статуса са варијаблама техничко-тактичке активност играча и играчица, указала је на високо значајне везе, како у мушкој тако и у женској популацији. Униваријатним и мултиваријатним анализама утврђене су значајне разлике између играча и играчица у квантитативним показатељима техничко-тактичке активности. Резултати указују на суштинске разлике између игара мушкараца и жена у агресивнијој игри у нападу и већој ефикасности постизања поена трећом лоптицом код играча у односу на играчице, док све остале квантитативне разлике у униваријатним анализама представљају последицу ове две значајне разлике. Помоћу бинарне логистичке регресионе анализе формирана су четири предикциона модела за предвиђање исхода сета и меча на основу праћених показатеља техничко тактичке активности у популацији играча и популацији играчица, који су приказали изузетно квалитетне метријске карактеристике.In the study, having the character of observational, exploratory ex post facto study, was examined the structure of space that manifests technical and tactical activities of top table tennis players (men n = 77; women n = 77), participants in the final Olympic tournament, at the final matches (men n = 154; women n = 154), i.e. 820 sets (men n = 423; women n = 397). Each of the players has been described through 9 variables, and technical and tactical activity in matches and sets was described through 17 variables. It was defined for the basic aims of the study to determine and to compare the space structure of technical and tactical activities of the players and defining of the selected relevant model characteristic of top male and female competitors of the world. The obtained results allow one to conclude that on the basis of technical and tactical activities of top male and female table tennis players in terms of competition with equal opponents, provides valid insight into the structure of the basic technical and tactical space described through 9 interpretable latent dimensions. The space structures in men and women populations did not differ qualitatively. Assaying the selection of the dominant hand on the efficiency of performing technical and tactical elements and performance effect points to the significant benefits of left-handed male as well as female players. The connection of the morphological status indicator with technical and tactical activity variables of male and female players, pointed to the highly significant relationship both in men and in women population. Univariate and multivariate analyses revealed significant differences between male and female players in the quantitative indicators of technical and tactical activities. Results indicate fundamental differences between the way how the men and women compete in the more aggressive play, in attack and greater efficiency in achieving point by third ball of male in relation to the female players, while all the other quantitative differences in univariate analysis represent the consequence of these two significant differences. Using binary logistic regression analysis four predictive models were formed for predicting the outcome of the set and match on the basis of monitored indicators of technical and tactical activities in the male and female population of the players showing exceptional metric characteristics quality