445 research outputs found
Air and Water Flowrate Optimisation for a Fan Coil Unit in Heat Pump Systems
No full textThe degradation in efficiency of auxiliary components in heating/cooling systems when operating at part load is frequently reported. Through the use of variable speed components, the supplied capacity can be reduced to match the required load and hence reduce unnecessary energy consumption. However, for fan coil units, difficulties can arise when optimizing fan and pump speeds at part load. Practically locating optimal water and air flow rates from readily available information and for varying supplied capacities is necessary, in order to reduce the fan coil power consumption. This research attempts to identify whether optimal fan and pump speeds exist for a fan coil unit and how they can be implemented, in a practical manner, in a system control applications. Using an empirical fan coil and pump model, the total power consumption (fan and pump) for different combinations of fan and pump speeds over a range of capacities was calculated. It was observed that, for a given capacity, an optimal combination of fan and pump speeds exists and there was a significant change in power consumption for different combinations of fan and pump speeds supplying the same capacity. A control strategy is described that utilizes a simple fan coil capacity estimation model, coupled with air and water flow rates, along with nominal design data. The pump speed is optimized using PID control to maintain the space temperature at the chosen set-point, which matches the supplied capacity to the required capacity. At set-time intervals, the capacity estimation model is utilized to optimize the water and air flow rates for the required capacity. The control strategy is evaluated, using a full building simulation model for a daily load profile and is compared to two baseline conditions: for no control of the fancoils/pump combination and for PID circulation control of the pump only. The optimal fan and pump speed control resulted in a 43% and 24% decrease in power consumption with compared to the no control baseline and the PID controlled circulation pump strategy, respectively
Fan Participation in the Age of Social Media – the Case of Kris Wu’s Fan Group
No full textThis thesis aims to explore how fans use social media to participate in activities relatedto the idol, and what is the level of participation of different fans in the fan group. Thisthesis used qualitative research methods – online observations and semi-structured indepth interviews to collect the empirical data, through focusing on the fan group of KrisWu. The theories of Jenkins and Carpentier are also applied to explore and describe theparticipatory practices of fans. By employing the theory of Jenkin’s participatoryculture to the first part of the analysis, the research results show that for the fans, socialmedia plays an important role in their participation, providing fans with a newenvironment to communicate and organize activities. Fan activities can be categorizedinto three major types: online consumption behaviors, fan text productions, and onlinesupporting activities. By applying the political and critical approach of participation, aswell as Carpentier’s four-level analytical model to the second part of the analysis, thisstudy finds that there are three sub-processes related to online fan communities – themanagement subprocess, the activity organization subprocess, and the subprocess oftext production and distribution. In each fan group, there are four different roles of fans– leaders, creators, supporters, and less active fans. Besides, through analyzing theidentities and decision-making moments, it can be said that although each fan isrelatively equal in the whole participatory process, there are still certain power relationsbetween each role of fans, especially in the process of fan group management
Barnlitteratur som medel och mål : Zhang Tianyi och den kinesiska barnlitteraturens utveckling
No full textThis thesis investigates the origin of children's literature in China and traces its evolution in connection with the author Zhang Tianyi, who is officially considered as one of the forerunners of Chinese children's literature. Children's literature in China is a little studied field, although the sources for a study are abundant. The thesis studies children's literature in its social context, which involves both social and economic aspects, such as education, popular literacy and the idea of childhood, but it is also seen as being part of a literary tradition. In the early 20th century Chinese literature was influenced both by Western literature and by national traditional forms. Zhang Tianyi, the author of satirical books in the 1930's, is here considered to be a representative of a return to traditional forms. In the thesis his literature for children is analysed as seen from a child's perspectiv, an aspect from below. Some other authors of the same generation - Ding Ling, Ba Jin, Lao She and Ling Shuhua - are singled out for a comparison and representative works are analysed in the same way. Zhang Tianyi's works of the 1950's are also analysed and compared to works by the authors Ren Dalin, Xiao Ping and Gao Xiangzhen and some of the prize-winning works in the 1954 nation-wide competition of children's literature. In the thesis I have tried to show how the literary form of children's books adapts to different purposes, in the first half of the 20th century when Chinese authors were seeking for a new public. The genre of children's literature became a mixture of literary styles and opened up for a literary dialogue between different classes of society. Zhang Tianyi pursues the tradition of satire in the shape of children's literature but his uncertainty about the genre helps to explain why he is seen as a forerunner of children's literature. Hopefully I have contributed to a better understanding of the origin of children's literature in China and the different aspects - social and literary - involved in the evolution of this literary genre. I also hope to have made a contribution to the research on the author Zhang Tianyi, whose writings for children need more scholarly attention
Density hysteresis and spin canting in rhombohedral trilayer graphene
No full textAbstract Spontaneous symmetry breaking leads to ordered phases, and hysteretic behavior often serves as a hallmark of emergent thermodynamic properties. Charge-neutral rhombohedral few-layer graphene is a strongly interacting system prone to layer antiferromagnetic (LAF) insulators, owing to its nearly flat bands with a high topological winding number. Here, in ultra-clean rhombohedral trilayer graphene devices—suspended to maximize interaction effects—we observe unexpected yet reproducible density hysteresis centered at the charge neutrality point (CNP), both at zero and finite electric fields. This hysteresis accentuates under an applied in-plane Zeeman field, but gradually weakens and eventually disappears as the temperature increases from 10 mK to 500 mK. These observations highlight the many-body nature of the LAF state, indicating a discontinuity in the chemical potential at the CNP and Zeeman field driven noncollinear spin canting. Our findings broaden the understanding of correlated phenomena in rhombohedral graphene and demonstrate both electric and magnetic control over antiferromagnetic order.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659National Science FoundationWelch Foundation http://dx.doi.org/10.13039/10000092
Nü zi, nü jie, nü jie: "Tian yi" yu wan Qing nü quan lun shu = Women, heroines, and women’s world : Tianyi and late Qing feminist discourse
No full textM.Phil.From 1907 to 1908, based in Tokyo, He Zhen何震 founded Nüzi fuquan hui 女子復權會 (Women’s Rights Recovery Association) and published its official journal Tianyi 天義 (Natural Justice). As an anarchist and feminist journal, Tianyi is an important material for studying late Qing feminist thoughts and practices. This thesis analyzes the theoretical, historical, and cultural significance of feminist discourse in Tianyi, which is divided into five chapters. The first chapter introduces the object, background, and methodology of the research. The second chapter “Women” (nüzi 女子) focuses on a series of articles advocating women’s liberation and equality between men and women published by He Zhen, discussing her radical theorization of gender and inequality, and also delineates the production of her images in modern Chinese histography and contemporary academia. The third chapter “Heroines” (nüjie 女傑) explores how Tianyi uses textual resources of different contexts to transform past and present, local and foreign female characters into revolutionary female models. The fourth chapter “Women’s World” (nüjie 女界) traces the transnational flow of knowledge, text, and information in Tianyi’s feminist discourse, and examines its spatial and world imagination, thereby considering late Qing feminism at the international level. The final chapter summarizes various meanings of anarcha-feminism in Tianyi and concludes the relationship between print media and gendered modernity in the late Qing era.1907至1908年間，何震旅居日本，發起成立「女子復權會」，創辦 《天義》作為機關刊物。《天義》以宣傳無政府主義與女權主義為主要內容，是研究晚清女權思想與實踐的重要資料。本文以《天義》中的女權論述為中心，分析其理論、歷史及文化意義，共分為五章。第一章是緒論，介紹《天義》概況、研究背景與研究思路。第二章「女子」以何震一系列倡導女子解放和男女平權的論說文為中心，討論她對性別概念的理解與對性別不平等的激進批判，同時分析她在歷史敘述與當代學界中的形象塑造過程。第三章「女傑」探討《天義》如何動用不同脈絡的文本資源，通過報刊這一新興的印刷媒體，將歷史和當下、本土與外國的女性人物轉化為革命的女性典範形象。第四章「女界」關注《天義》中女權論述發生的國際化背景，追蹤相關知識、文本、信息的流動，並觀察其對空間與世界的想像，展現晚清女權思想在國際層面的意義。第五章是結語，綜述《天義》無政府女權主義的多重意義，總結晚清時期印刷媒體與性別現代性的關係。盛之帆."2020年9月".Parallel title from English abstract.Thesis M.Phil. Chinese University of Hong Kong 2020.Includes bibliographical references (leaves 110-120).Abstract also in English.Title from PDF title page (viewed on March 17, 2022).Sheng Zhifan
Spatial dynamics of microbial populations driven by social interactions and horizontal gene transfer
No full textThe functions of the microbial ecosystems are closely related to the spatial structures formed by microbial communities. Yet, it is not well understood what determines, controls and regulates the spatial dynamics of microbial populations. In this study, we use synthetic microbial consortia as our experimental models, to explore the factors contributing to the microbial populations’ spatial dynamics, owing to their great controllability and reduced system complexity compared to native existing ecosystems. Upon a systematic investigation on the relationship between the microbial spatial structures and factors influencing their spatial dynamics, we found that interaction topologies and horizontal gene transfers drive the spatial structure formations of bacterial communities. Spatial interaction scales, growth rates and antibiotic selection forces are other modulators that affect the spatial structures. Our results confirm social interactions and horizontal gene transfers as two key determinants of the microbial spatial dynamics, providing insights into microbial spatial organization and synthetic ecosystem engineering.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2021-05-01The student, Tianyi Li, accepted the attached license on 2019-04-19 at 16:32.The student, Tianyi Li, submitted this Thesis for approval on 2019-04-19 at 16:58.This Thesis was approved for publication on 2019-04-23 at 15:20.DSpace SAF Submission Ingestion Package generated from Vireo submission #13796 on 2019-08-22 at 16:23:25Made available in DSpace on 2019-08-23T20:48:21Z (GMT). No. of bitstreams: 2
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Quantum cascade of correlated phases in trigonally warped bilayer graphene
No full textDivergent density of states offers an opportunity to explore a wide variety of correlated electron physics. In the thinnest limit, this has been predicted and verified in the ultraflat bands of magic-angle twisted bilayer graphene1,2,3,4,5, the band touching points of few-layer rhombohedral graphite6,7,8 and the lightly doped rhombohedral trilayer graphene9,10,11. The simpler and seemingly better understood Bernal bilayer graphene is also susceptible to orbital magnetism at charge neutrality7 leading to layer antiferromagnetic states12 or quantum anomalous Hall states13. Here we report the observation of a cascade of correlated phases in the vicinity of electric-field-controlled Lifshitz transitions14,15 and van Hove singularities16 in Bernal bilayer graphene. We provide evidence for the observation of Stoner ferromagnets in the form of half and quarter metals10,11. Furthermore, we identify signatures consistent with a topologically non-trivial Wigner–Hall crystal17 at zero magnetic field and its transition to a trivial Wigner crystal, as well as two correlated metals whose behaviour deviates from that of standard Fermi liquids. Our results in this reproducible, tunable, simple system open up new horizons for studying strongly correlated electrons
Targeting the ovary : mapping mechanisms to link endocrine-disrupting chemicals to female fertility
No full textIn recent decades, growing attention has been paid to endocrine-disrupting chemicals (EDCs) as mounting evidence suggests that they can cause detrimental reproductive outcomes in animals and humans. Even though epidemiological studies show the link between EDC exposure and adverse reproductive outcomes such as sub-fertility, longer time-to-pregnancy, and decreased ovarian reserve in women, the underlying mechanisms are not fully elucidated. This is challenging for chemical regulation as we need mechanistic information to properly identify EDCs that may cause detrimental effects. In this thesis, we aim to map the mechanisms linking EDCs to female infertility, identify potential biomarkers of exposure using in vitro culture systems, and carry out cross-species comparisons using rat models.Paper I characterized the effects of in vitro culture alone on ovarian cortical tissue using transcriptomic profiling and investigated the feasibility of using this model to study the effects of exposure to EDCs on the human ovary. RNA sequencing (RNA-seq) revealed a marked change induced by tissue fragmentation and culture itself, including changes in energy metabolism (i.e., glycolysis). Follicles were activated to grow during the culture, which could be explained by the disruption of the Hippo signaling, and partially, by upregulation of the glycolysis pathway. Papers II-III investigated the effects of selected chemicals (pharmaceuticals: DES, KTZ; persistent organic pollutants (POPs): HCB, DDE, PCB156, PCB180, PFOS, and their mixture) on ovarian cells and tissue in culture. All exposures affected follicle growth in culture. Additionally, exposure to POPs resulted in increased follicle atresia in in vitro culture. Using transcriptomic profiling, we found disruption of lipid biology and energy homeostasis as well as increased oxidative stress as potential novel mechanisms connecting chemical exposures to disrupted folliculogenesis. Furthermore, we identified stearoyl-CoA desaturase (SCD) and 7-dehydrocholesterol reductase (DHCR7) as potential biomarkers of chemical exposure.Papers IV-V investigated the reproductive outcomes induced by DES and KTZ exposure in rats and explored the changes in endpoint sensitivity during pubertal and adult exposure. Moreover, we also developed and assessed the feasibility of using surface photo counting (SPC) as a fast tool to prioritize chemical exposure groups for further histological evaluation. In general, we found that high-dose exposure to DES and KTZ disrupted folliculogenesis in rats. When comparing endpoint sensitivity between different exposure periods, our results suggested that no profound differences can be observed, although pubertal exposure allowed the inclusion of vaginal opening as a sensitive endpoint to estrogenic chemicals. In addition, we showed that the quantification results obtained from the SPC method were significantly correlated with that of traditional histological assessment. Therefore, SPC could be used as a complementary method to prioritize groups for histology analysis.In summary, in vitro ovarian tissue culture can be used to study the impact of chemicals on follicle survival and growth, and underlying mechanisms. Utilizing this model, we found that exposure to the selected chemicals affected folliculogenesis, through disruption of their energy metabolism and increased oxidative stress. Similarly, we showed that high-dose DES and KTZ exposure disrupted follicle growth in rats, but not in low- and middle-dose groups. This suggests that the investigated endpoints in the in vivo study were not sensitive enough. It advocates the need for a sensitive and human-relevant assay for the screening of EDCs present in the global market. The identified common signatures and biomarkers might be used as a base for the future development of such screening assays after validation. Even though this is a small step, we are moving towards the future of a chemical-safe world.List of scientific papersI. Jie Hao1*, Tianyi Li1, Manuel Heinzelmann, Elisabeth Moussaud, Filipa Lebre, Kaarel Krjutškov, Anastasios Damdimopoulos, Catarina Arnelo, Karin Pettersson, Ernesto Alfaro-Moreno, Cecilia Lindskog, Majorie van Duursen, Pauliina Damdimopoulou. Effects of in vitro activation vs fragmentation on human ovarian tissue and follicle growth in culture. 1Equal contribution *Corresponding author [Submitted]II. Tianyi Li*, Paraskevi Vazakidou, Pim E G Leonards, Anastasios Damdimopoulos, Eleftheria Maria Panagiotou, Catarina Arnelo, Kerstin Jansson, Karin Pettersson, Kiriaki Papaikonomou, Majorie van Duursen, Pauliina Damdimopoulou. Identification of biomarkers and outcomes of endocrine disruption in human ovarian cortex using In Vitro Models. Toxicology. 2023 Feb;485:153425. *Corresponding author https://doi.org/10.1016/j.tox.2023.153425 III. Tianyi Li, Richelle D Björvang, Jie Hao*, Valentina Di Nisio, Anastasios Damdimopoulos, Cecilia Lindskog, Kiriaki Papaikonomou, Pauliina Damdimopoulou. Persistent Organic Pollutants Dysregulate Energy Homeostasis in Human Ovaries In Vitro. *Corresponding author. [Submitted]IV. Julie Boberg, Tianyi Li, Sofie Christiansen, Monica Kam Draskau, Pauliina Damdimopoulou, Terje Svingen, and Hanna KL Johansson*. Comparison of female rat reproductive effects of pubertal versus adult exposure to known endocrine disruptors. Front Endocrinol (Lausanne). 2023 Oct 3:14:1126485. *Corresponding author https://doi.org/10.3389/fendo.2023.1126485 V. Tianyi Li*, Julie Boberg, Hanna K L Johansson, Valentina Di Nisio, Sofie Christiansen, Terje Svingen, Pauliina Damdimopoulou. Quantitative analysis of ovarian surface photographs as a tool for assessment of chemical effects on folliculogenesis and ovulation in rats. Reprod Toxicol. 2023 Aug 1;119:108416. *Corresponding author https://doi.org/10.1016/j.reprotox.2023.108416 </p
A hybrid method to select morphometric features using tensor completion and F-score rank for gifted children identification
No full textGifted children are able to learn in a more advanced way than others, probably due to neurophysiological differences in the communication efficiency in neural pathways. Topological features contribute to understanding the correlation between the brain structure and intelligence. Despite decades of neuroscience research using MRI, methods based on brain region connectivity patterns are limited by MRI artifacts, which therefore leads to revisiting MRI morphometric features, with the aim of using them to directly identify gifted children instead of using brain connectivity. However, the small, high dimensional morphometric feature dataset with outliers makes the task of finding good classification models challenging. To this end, a hybrid method is proposed that combines tensor completion and feature selection methods to handle outliers and then select the discriminative features. The proposed method can achieve a classification accuracy of 93.1%, higher than other existing algorithms, which is thus suitable for the small MRI datasets with outliers in supervised classification scenarios.Fil: Zhang, Jin. Nankai University; ChinaFil: Feng, Fan. Nankai University; ChinaFil: Han, TianYi. Nankai University; ChinaFil: Duan, Feng. Nankai University; ChinaFil: Sun, Zhe. Riken. Brain Science Institute; JapónFil: Caiafa, César Federico. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Solé Casals, Jordi. Central University of Catalonia; Españ
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