Shen, Siduo. / Thesis Ph.D. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 147-161). / Abstracts also in Chinese. / Title from PDF title page (viewed on 15 September, 2016). / Shen, Siduo = Duo dian xie zuo : gan rao jian qing yu gan rao li yong / Shen, Siduo.

Selecting an appropriate model is a crucial issue for applying structural equation models (SEMs) in real applications. Due to the model complexity, however, it is quite challenging to perform model selection on semiparametric SEMs with functional structural equations. In this thesis, we propose a modified Bayesian adaptive group Lasso procedure to perform model selection and estimation for semiparametric SEMs. By considering a novel formulation of basis expansions to approximate the unknown functions with certain penalties imposed, we are able to introduce a partial linear structure that combines the advantages of linear and nonparametric formulations for structural equations. The nonlinear, linear, or none structures in structural equations can be automatically detected with the proposed method. In addition, the group Lasso with adaptive penalties not only largely alleviates the model selection difficulties caused by the group effects and correlations introduced by basis expansions of latent variables, but also reduces the bias of traditional Lasso procedures. Simulation studies demonstrate that the proposed methodology performs satisfactorily. The proposed method is applied to analyze a real data set of diabetic kidney disease, which provides us some meaningful insights. / 在结构方程模型的实际应用中，选择一个合适的模型是一个核心问题。但是由于模型的复杂性，对于含有函数型结构的半参数结构方程模型进行模型选择十分困难。在本文中，我们提出了一种新的贝叶斯自适应群Lasso，并应用它来对半参数结构方程模型同时进行参数估计和模型选择。我们在非参数结构方程模型中引入了部分线性结构，并通过一种新的基底函数展开来近似结构方程里的未知函数。这种结构同时具备了线性模型和非参数模型的优势。本文的方法可以自动识别半参数结构方程模型里面的非线性和线性结构，并筛除不重要的变量。这种带有自适应惩罚的群Lasso不仅减小了传统Lasso方法在估计参数时产生的偏差，而且解决了由潜变量的基底表示导致的组效应和相关性引起的模型选择的困难。由模拟实验的结果可以看出本文提出的方法十分有效。我们还应用所提出的方法分析了一组关于糖尿病型肾病的数据，并得到了一些有意义的结果。 / Feng, Xiangnan. / Thesis M.Phil. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 51-56). / Abstracts also in Chinese. / Title from PDF title page (viewed on 18, October, 2016). / Detailed summary in vernacular field only.

We study sealed-bid first-price auction for one commodity. While traditional model (Vickrey, 1961) consists of only one stage of bidding, we introduce a new model by adding a new stage of application before the stage of final bidding. In the application stage, each bidder submits a tentative sealed bid, and it is then announced who is the tentative winner. Then in the bidding stage, each bidder gives his final (sealed) bid, and the final winner receives the commodity by paying his final bid. / To analyze the model, we use the equilibrium concepts of Weak Perfect Bayesian Equilibrium (WPBE). The role of the tentative bid can be regarded as a pre-play communication between the bidders. We obtain three main results: / 1) Our Theorem 1 shows that every equilibrium in the traditional one-stage model can be realized as a WPBE in our two-stage model, and the tentative bids of bidders are independent of their private values. / 2) Our Theorem 2 shows that if one requires the tentative bids of bidders to be strictly increasing with their private values, then no symmetric WPBE exists. / 3) Our Theorem 3 shows that if each bidder uses a weakly increasing step function as the tentative bidding strategy, then no symmetric WPBE exists. / Our work suggests that if each bidder is free to change his final bid from the tentative bid, then introducing the application system does not affect the outcome of the auction. / 本文章主要論及首價密封投標拍賣。傳統的拍賣只有一個階段﹐而在這篇文章我們會在傳統拍賣前加一個「申請階段」。在「申請階段」中﹐每名投標者需要遞交一個意向價格﹐拍賣者再根據意向價格宣佈那位投標者成為申請人。之後的拍賣中﹐每名投標者會遞交一個最終價格﹐最高價者會成功投得該項商品。 我們會使用「弱完美貝葉斯均衡」(WPBE)的概念去分析本文中的模型。我們得到以下的三個主要結果: / 1)在定理一中﹐我們發現所有傳統單一階段拍賣中的均衡點, 在我們新申請拍賣的模型中﹐都會是弱完美貝葉斯均衡(WPBE)﹐而且投標者的意向價格會和他們對商品的自身價值沒有關係。 / 2)在定理二中﹐如果投標者的意向價格函數和對商品的自身價值是嚴格遞升﹐那麼對稱性弱完美貝葉斯均衡不會存在。 / 3)在定理三中﹐如果申請階段的策略是遞升階梯函數﹐那麼對稱性弱完美貝葉斯均衡不會存在。 / 我們的研究指出, 當投標者可以不受意向價格規範而自己更改最終價格﹐那麼加入「申請階段」也不會改變拍賣的結果。 / Ho, Man Kit. / Thesis M.Phil. Chinese University of Hong Kong 2014. / Includes bibliographical references (leave 41). / Abstracts also in Chinese. / Title from PDF title page (viewed on 18, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

En los últimos años, el problema de la inseguridad ciudadana ha alcanzado uno de los lugares prioritarios en la agenda gubernamental. El Estado peruano ha optado por abordar este problema desarrollando una serie de estrategias que van desde la creación de sistemas de medición de la seguridad pública de naturaleza intersectorial, hasta el reforzamiento de espacios destinados a promover la seguridad y convivencia ciudadana al interior de sus diversos niveles de gobierno. Sobre esto último, un caso emblemático es la Gerencia de Seguridad Ciudadana de la Municipalidad Metropolitana de Lima (GSGC). La GSGC contribuye con el objetivo del Estado de mitigar el problema de la inseguridad ciudadana a través de acciones directas como la planificación y ejecución de operaciones de patrullaje general y selectivo, en apoyo de la Policía Nacional del Perú, prestando auxilio y protección al vecindario para la protección de su vida e integridad física, y la prestación de auxilio, protección, orden, seguridad y una convivencia pacífica de la comunidad. Asimismo, esta Gerencia cuenta con una plataforma tecnológica de generación de datos sobre crimen y seguridad que, posteriormente, serán empleados para el desarrollo de estrategias con miras a solucionar este problema público. Sin embargo, en los últimos cuatro años, dentro del ámbito de Lima Metropolitana, tanto la percepción de inseguridad, las tasas de victimización y la cantidad de denuncias por delito no han mostrado una evolución favorable; sino que, por el contrario, se ha visto una constante tendencia al alza. En ese sentido, la pregunta que dirige esta investigación es ¿cuál es el impacto de la información generada a partir de las plataformas de recopilación de datos sobre crimen y seguridad en el diseño de las estrategias de la Gerencia de Seguridad Ciudadana de la Municipalidad Metropolitana de Lima entre el 2010 y el 2014? / Tesis

This thesis aims to address two key issues in two-dimensional (2D) convective turbulence: particle dispersion and statistics of the small-scale turbulence. / Particle dispersion plays a key role in understanding transport and mixing in turbulence, which is also significant to natural processes such as pollutants spreading in the atmosphere. To study particle dispersion in 2D convective turbulence, we use particle tracking velocimetry (PTV) technique in a soap film. The Taylor-scale Reynolds number of the system is Rλ ≈ 155. It is found that the particle dispersion law strongly depends on the initial separation. In the present system, mean square separations of particle pairs with initial separation in the inertial range grow exponentially and the ones with initial separation close to Kolmogorov length scale follow Richardson scaling law for a short range, which is consistent with the measurement in three-dimensional (3D) case and numerical result. We attribute exponential growth to the fact that the size of thermal plumes, which is regarded as energy injection scale in the present system, is comparable to the integral length scale of the flow, thus, only enstrophy cascading range is achieved for large initial separations, where exponential growth was predicted theoretically. The probability density functions (PDFs) of separation for particle pairs with initial separation close to Kolmogorov length scale display stretched exponential decay and the ones with initial separation in the inertial range exhibit exponential decay. On the other hand, for the particle pairs with initial separation near the integral length scale, Gaussian PDF is observed. The correlation of separation is also found to be initial separation dependent. The single-particle dispersion follow Taylor’s prediction. The acceleration PDF measured in the whole field deviates significantly from Gaussian distribution and displays extreme intermittency, with fluctuations racing up to 60 times of the root-mean-square values. / 本論文主要研究二維湍流熱對流中的兩個問題：粒子擴散和小尺度湍流的統計特性。 / 粒子擴散不僅對湍流運輸和混合特性的理解至關重要，而且在自然過程，如大氣污染物粒子擴散中扮演重要角色。我們通過粒子示蹤測速的方法，在薄膜中研究了二維湍流熱對流粒子的擴散。該係統對應的泰勒微尺度雷諾數是Rλ ≈ 155。研究發現，當粒子對的初始相對分離落在慣性區時，分離以指數形式增長；而當初始分離接近於Kolmogorov長度尺度時，分離在短時間以Richardson標度律演變，該發現和三維實驗結果以及數值模擬結果一致。分析表明，指數增長是由於粒子被困在相幹結構中，如熱羽流，其尺度與湍流積分長度尺度相當。我們認為，該係統中能量注入尺度即為熱羽流之尺度。這樣，只有渦量級串區在該系統中實現，理論上，可以觀察到分離的指數增長。該研究發現對於解釋污染物顆粒在大氣中長時間聚集有重要意義。研究亦表明，分離尺度接近於耗散區時，分離的概率密度函數以廣義指數形式衰減；落在慣性區時，其概率密度函數以指數形式衰減；接近於積分長度尺度時，以高斯形式衰減。研究表明，分離的相關性也依賴於初始分離。研究表明，單粒子擴散遵循泰勒擴散理論。實驗表明，全場加速度的概率密度函數不同於高斯分佈，並且體現出強間歇性和波動，加速度的波動可以達到特征速度的60倍。 / Li, Xiangyu = 薄膜中二維湍流熱對流實驗研究 / 李翔宇. / Thesis M.Phil. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 42-45). / Abstracts also in Chinese. / Title from PDF title page (viewed on 12, October, 2016). / Li, Xiangyu = Bo mo zhong er wei tuan liu re dui liu shi yan yan jiu / Li Xiangyu. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

Maxwell’s equations are a set of partial differential equations that describe the classic electromagnetic problems, electrodynamics etc. Effective numerical methods are derived to solve the equations in the past decades, and continued to be of great interest to be developed to its completion. In this thesis, we introduce and propose numerical methods using staggered meshes that deal with both two dimensional and three dimensional space problem in polygonal and general curved domains. / Finite difference method, finite volume method, spectral method and staggered discontinuous Galerkin method are discussed in the thesis. A forth order finite difference method using Taylor expansion technic is proposed. The integral form of the original Maxwell’s equations give rise to methods based on more general domain. For the finite volume method, covolume methods both on the cyclic polygon elements and noncyclic polygon elements are derived. To derive a higher order accurate method, staggered discontinuous Galerkin method based on the same domain decomposition present in the finite volume method use Nedelec elements is derived in two dimensional space, and spectral method using nodal high-order method operate on a general domain in 3D with flexible domain geometry is introduced. Numerical results are shown to show the performance oft he above mentioned approximation methods in 2D case. / 麥克斯韋方程組是一組描述經典電磁問題，電磁力學的偏微分方程。在過去數十年，行之有效的偏微分方程數值解已經被推導出並用於求解該方程，該問題現在仍然吸引著學者極大的興趣，並日臻完善。在這篇論文中，我們介紹並提出一些運用曲域交錯網格數值方法在二維和三維的多面體和更一般幾何體處理麥克斯韋方程組問題。 / 本論文對有限差分法，有限體積法，光譜法和交錯間斷有限元方法進行了討論。利用泰勒展開式這一方法推導出一個二維的四階有限差分方法。基於原來的麥克斯韋方程組的積分形式所得到的數值方法更適用於更普遍的域。對於有限體積法，對循環多邊形元素和非環狀多邊形元素的有限體積方法都將被導出。為了得到一個更高階準確的方法，基於有限體積法中使用的域分解方法，使用Nedelec元素，推導了二維空間的高階有限元方法。基於頂點高階數值方法的光譜法對於三維一般定義域的幾何形態更為靈活適用。在二維的定義域中，數值模擬結果驗證上述數值方法的精確性。 / Jian, Fangqiong. / Thesis M.Phil. Chinese University of Hong Kong 2014. / Includes bibliographical references (leaves 62-65). / Abstracts also in Chinese. / Title from PDF title page (viewed on 07, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

We study optimal replacement and abandonment decisions for real assets, when both revenues and costs are uncertain and deteriorate with age. We develop an implicit representation of the renewal boundary as the solution to a set of simultaneous equations. This quasi-analytical method has the merit of computational ease and transparency. We show that the correlation between revenues and operating costs has a significant influence on the renewal boundary, and that the increase in revenue immediately following a renewal has a greater relative influence on the boundary than either operating cost or renewal cost. The quasi-analytical method is sufficiently flexible to deal with other real option models involving 2 variables.

Syftet med den hä̈r uppsatsen ä̈r att undersö̈ka huruvida det finns skillnader vad gäller utrymme och framstä̈llningen av partiledarna i Aftonbladet, Dagens Nyheter, Expressen och Svenska Dagbladet under en månad före det svenska riksdagsvalet 2014. Vi har också undersökt om skillnaderna beror på könstillhörighet eller partitillhörighet. Som grund för undersökningen ligger en kvantitativ innehållsanalys. Materialet består av 540 artiklar och 565 tillhörande bilder. Artiklarna är hämtade från Retriever Mediedatabas och kommer från ovan nämnda tidningar, de är publicerade från den 14 augusti till och med den 14 september 2014. Resultaten visar att det finns skillnader i hur stort utrymme respektive partiledare får. Partiledarna för de största partierna får mest medieutrymme. Undersökningen visar att det även finns skillnader i framställningen. Åkesson framställs klart mest negativt, Schyman framställs mest positivt medan bilden av Lööf i stor utsträckning är vinklad åt båda hållen. Vi har sett exempel på användandet av medielogik i framställningen och vad vi uppfattar som stereotyp framställning, till exempel att de kvinnliga partiledarna ler på bild i högre grad än sina manliga kollegor. Överlag är skillnaderna dock inte stora.

Este trabalho tem como finalidade destacar a figura do negro como personagem literário, (re)contando sua história no continente americano. Ao tomar a palavra, o negro tem a oportunidade de narrar sua trajetória através do seu ponto de vista e algumas características como a passividade perante o sistema escravocrata vão sendo desconstruídas. As obras analisadas – Viva o povo brasileiro, de João Ubaldo Ribeiro e Changó, el gran putas, de Manuel Zapata Olivella – exemplificam as mudanças que estão ocorrendo na poética e na visão de mundo do romance histórico. Com o advento das teorias pós-ocidentais na América Latina, as vozes que eram silenciadas passam a ser ouvidas e uma nova história é contada: a partir dos fatos históricos, resgata-se uma história onde o mito também tem o seu lugar. A nova teorização latino-americana engloba conceitos como transculturação, entre-lugar e crioulização, demonstrando a emergência de um terceiro espaço onde surgem novos sujeitos transculturados representativos da mistura das várias culturas que povoaram as Américas.

Este trabalho tem como finalidade destacar a figura do negro como personagem literário, (re)contando sua história no continente americano. Ao tomar a palavra, o negro tem a oportunidade de narrar sua trajetória através do seu ponto de vista e algumas características como a passividade perante o sistema escravocrata vão sendo desconstruídas. As obras analisadas – Viva o povo brasileiro, de João Ubaldo Ribeiro e Changó, el gran putas, de Manuel Zapata Olivella – exemplificam as mudanças que estão ocorrendo na poética e na visão de mundo do romance histórico. Com o advento das teorias pós-ocidentais na América Latina, as vozes que eram silenciadas passam a ser ouvidas e uma nova história é contada: a partir dos fatos históricos, resgata-se uma história onde o mito também tem o seu lugar. A nova teorização latino-americana engloba conceitos como transculturação, entre-lugar e crioulização, demonstrando a emergência de um terceiro espaço onde surgem novos sujeitos transculturados representativos da mistura das várias culturas que povoaram as Américas.