27 research outputs found
Rigidity of local holomorphic maps between Hermitian symmetric spaces
No full textIn this dessertaion, rigidity of local holomorphic maps between Hermitian symmet ric spaces has been studied. For local holomorphic maps from an irreducible Hermi tian symmetric spaces of compact type to itself, which is equipped with a canonical K¨ahler-Eisntein metric, we show that every map extends to an isometry of the mani fold, provided that the maps satisfy a measure-preserving equation and are generically non-degenerate. To establish the rigidity result, a notion of Serge variety and Segre family in the algebraic setting is introduced. Before obtaining the main theorem, we first prove a basic property for partially degenerate holomorphic maps in a general set ting. Then we establish the Nash-algebraicity for one of these maps by applying this basic property. Here the explicit expression of the mimimal embedding of the manifold into a certain projective space is essentially used. Standard monodormy argument is then applied to show the rationality for this Nash-algebraic map. Lastly by a covering trick we show that the map is a birational map and further an isometry. Hence by induction, we conclude the main theorem. This thesis is based on a joint work with Xiaojun Huang and Ming Xiao ( [FHX])Ph.D.Includes bibliographical referencesby Hanlong Fan
Wai lai dian shi mei jie de shi yong yu xiao guo fen xi: Shenzhen qing shao nian shou kan Xianggang dian shi yan jiu.
No full text稿本論文(碩士)--香港中文大學硏究院新聞學系,1992.參考文獻: leaves 137-143黃漢龍.Chapter 第一章 --- 緒 論 --- p.1Chapter 一. --- 緒 言 --- p.1Chapter 二. --- 硏究背景、動機與目的 --- p.2Chapter 三. --- 研究對象與提問 --- p.5Chapter 四. --- 研究意義 --- p.7Chapter 五. --- 硏究方式與内容結構 --- p.8Chapter 第二章 --- 理論基礎與文獻探討 --- p.12Chapter 一. --- 大眾傳媒的功能 --- p.13Chapter 二. --- 媒介效果與潛化分析 --- p.16Chapter (一) --- 「社會文化模式」與「心理功 力模式」媒效果 --- p.16Chapter (二) --- 「文化指標」與潛化分析硏究 --- p.20Chapter 1. --- 「文化指標」與「暴力素描」 --- p.20Chapter 2. --- 「暴力素描」與「潛化分析」 --- p.21Chapter 3. --- 「潛化分析」的批評 --- p.23Chapter 4. --- 「潛化分析」的研究的發展 --- p.26Chapter 三. --- 國際電視傳播效果硏究 --- p.28Chapter (一) --- 美國電視跨國傳统效果硏究 --- p.28Chapter (二) --- 美國電視跨國潛化效果研究 --- p.29Chapter 四. --- 本文就「潛化分析」分析架構之演化 --- p.33Chapter 五. --- 本硏究潛化指標之構思過程 --- p.40Chapter 六. --- 價值觀念與電視效果相關硏究 --- p.42Chapter (一) --- 羅基價值研究 --- p.42Chapter (二) --- 電視與價值觀念之傳统效果研究 --- p.44Chapter (三) --- 電視與價值觀念潛化效果之初探性研究 --- p.46Chapter (四) --- 個人主義與集體主義價值之分類 --- p.48Chapter 七. --- 電視與休閒生活方式相關硏究 --- p.57Chapter (一) --- 休閒的涵義 --- p.58Chapter (二) --- 休閒生活方式形成的理論 --- p.59Chapter (三) --- 休閒生活方式與媒介效果硏究 --- p.60Chapter (四) --- 外來時尚與本土休閒生活方式 --- p.62Chapter 第三章 --- 硏究設計與分析架構 --- p.66Chapter 一. --- 研究假設 --- p.66Chapter 二. --- 研究工具與主要變項之界定 --- p.67Chapter 三. --- 研究抽樣 --- p.84Chapter 四. --- 统計方法與分析步驟 --- p.86Chapter 第四章 --- 硏究結果與資料分析 --- p.90Chapter 一. --- 樣本特徵 --- p.90Chapter 二. --- 假設驗證與分析 --- p.95Chapter (一) --- 收看港視與價值觀念 --- p.95Chapter 1. --- 受訪者價值之分析 --- p.95Chapter 2. --- 價值次數分配分析 --- p.97Chapter 3. --- 收看港視與個人主義價值 --- p.99Chapter -1 --- 收看港視與個人目標價值 --- p.100Chapter -2 --- 收看港視與個人能力價值 --- p.102Chapter 4. --- 收看港視與集體主義價值 --- p.103Chapter (二) --- 收看港視與休閒生活方式 --- p.105Chapter 1. --- 受訪者休閒喜好分析 --- p.105Chapter 2. --- 休閒喜好指標次數分配分析 --- p.108Chapter 3. --- 收看港視與外來時尚休閒活動 --- p.109Chapter 4. --- 收看港視與本土傳统休閒活動 --- p.111Chapter 第五章 --- 結論與討論 --- p.115註釋 --- p.134中文書目 --- p.137英文書目 --- p.138受訪中學生背景資料問
Canonical blow-ups of Grassmannians I: How canonical is a Kausz compactification?
No full textIn this paper, we develop a simple uniform picture incorporating the Kausz compactifications and the spaces of complete collineations by blowing up Grassmannians according to a torus action . We show that each space of complete collineations is isomorphic to any maximal-dimensional connected component of the -fixed point scheme of a Kausz-type compactification. We prove that the Kausz-type compactification is the total family over the Hilbert quotient which is isomorphic to the space of complete collineations. In particular, the Kausz compactifications are toroidal embeddings of general linear groups in the sense of Brion-Kumar. We also show that the Kausz-type compactifications resolve the Landsberg-Manivel birational maps from projective spaces to Grassmannians, by comparing Kausz\u27s construction with ours. As an application, by studying the foliation we derive resolutions of certain birational maps among projective bundles over Grassmannians. The results in this paper are partially taken from the first author\u27s earlier arxiv post (Canonical blow-ups of grassmann manifolds, arxiv:2007.06200), which has been revised and expanded in collaboration with the second author.A funding source is added, and some typos are corrected. All comments are welcome
Investigating Helium-Induced Thermal Conductivity Degradation in Fusion-Relevant Copper: A Molecular Dynamics Approach
No full textCopper alloys are critical heat sink materials for fusion reactor divertors due to their high thermal conductivity (TC) and strength, yet their performance under extreme particle bombardment and heat fluxes in future tokamaks requires enhancement. While neutron-induced transmutation helium affects the properties of copper, the atomistic mechanisms linking helium bubble size to thermal transport remain unclear. This study employs non-equilibrium molecular dynamics (NEMD) simulations to isolate the effect of bubble diameter (10, 20, 30, 40 Å) on TC in copper, maintaining a constant He-to-vacancy ratio of 2.5. Results demonstrate that larger bubbles significantly impair TC. This reduction correlates with increased Kapitza thermal resistance and pronounced lattice distortion from outward helium diffusion, intensifying phonon scattering. Phonon density of states (PDOS) analysis reveals diminished low-frequency peaks and an elevated high-frequency peak for bubbles >30 Å, confirming phonon confinement and localized vibrational modes. The PDOS overlap factor decreases with bubble size, directly linking microstructural evolution to thermal resistance. These findings elucidate the size-dependent mechanisms of helium bubble impacts on thermal transport in copper divertor materials
6. Comparative Efficiency. Analysis of Australian and Indonesian Ports
No full text6.0 Introduction Logistics is a critical element of a country’s trading ability and is central to the economic growth of the country, since it enables effective connection of trade through both domestic and international logistics networks. Due to the close geographic proximity of Australia and Indonesia, trade plays an important role in each country’s economy (DFAT 2019). In 2016, Australia came in 8th and 11th place as the principal import source and export destination for Indonesia respect..
A Comparative Study of Neutron Shielding Performance in Al-Based Composites Reinforced with Various Boron-Containing Particles for Radiotherapy: A Monte Carlo Simulation
No full textThis study aimed to assess and compare the shielding performance of boron-containing materials for neutrons generated in proton therapy and used in boron neutron capture therapy (BNCT). Five composites, including AlB2, Al-B4C, Al-TiB2, Al-BN, and Al-TiB2-BN, were selected as shielding materials, with concrete used as a benchmark. The mass fraction of boron compounds in these materials ranged from 10% to 50%. The Monte Carlo toolkit Geant4 was employed to calculate shielding parameters, including neutron ambient dose equivalent, dose values, and macroscopic cross-section. Results indicated that, compared to concrete, these boron-containing materials more effectively absorb thermal neutrons. When the boron compound exceeds 30 wt.%, these materials exhibit better shielding performance than concrete of the same thickness for neutrons generated by protons. For a given material, its shielding capability increases with boron content. Among the five materials when the material thickness and boron compound content are the same, the shielding performance for neutrons generated by protons, from best to worst, is as follows: Al-TiB2, Al-B4C, AlB2, Al-TiB2-BN, and Al-BN. For BNCT, the shielding performance from best to worst is in the following order: Al-B4C, AlB2, Al-TiB2, Al-TiB2-BN, and Al-BN. The results of this study provide references and guidelines for the selection and optimization of neutron shielding materials in proton therapy and BNCT facilities
Self-supervised learning of hologram reconstruction using physics consistency
No full textThe past decade has witnessed transformative applications of deep learning in
various computational imaging, sensing and microscopy tasks. Due to the
supervised learning schemes employed, these methods mostly depend on
large-scale, diverse, and labeled training data. The acquisition and
preparation of such training image datasets are often laborious and costly,
also leading to biased estimation and limited generalization to new sample
types. Here, we report a self-supervised learning model, termed GedankenNet,
that eliminates the need for labeled or experimental training data, and
demonstrate its effectiveness and superior generalization on hologram
reconstruction tasks. Without prior knowledge about the sample types to be
imaged, the self-supervised learning model was trained using a
physics-consistency loss and artificial random images that are synthetically
generated without any experiments or resemblance to real-world samples. After
its self-supervised training, GedankenNet successfully generalized to
experimental holograms of various unseen biological samples, reconstructing the
phase and amplitude images of different types of objects using experimentally
acquired test holograms. Without access to experimental data or knowledge of
real samples of interest or their spatial features, GedankenNet's
self-supervised learning achieved complex-valued image reconstructions that are
consistent with the Maxwell's equations, and its output inference and object
solutions accurately represent the wave propagation in free-space. GedankenNet
framework also exhibits resilience to random, unknown perturbations in the
physical forward model, including changes in the hologram distances, pixel size
and illumination wavelength. This self-supervised learning of image
reconstruction tasks creates new opportunities for various inverse problems in
holography, microscopy and computational imaging fields.Comment: 45 pages, 6 Figure
excavation strategies
No full textAs urbanization progresses, the demand for high-rise buildings and underground spaces is growing, and the need for firm geotechnical construction materials, efficient excavation methods, accurate testing instruments, and innovative geotechnical engineering theories and technologies is increasing. By investigating the phenomena of strengthening and toughening in nature, hydrophobic and ice-phobic, friction anisotropy and drilling as well as excavation, etc, researchers have found that organisms have distinctive external morphology and organization. By imitating the external morphology, structural characteristics or movement mechanism of organisms, novel ideas, new principles, and innovative theories can be provided for the innovation and sustainable development of geotechnical engineering. This paper mainly expounds on the bio-inspired application in geotechnical engineering from three perspectives: geo-materials, geotechnical components, and drilling & excavation equipment, and lists typical application cases. In conclusion, this paper presents a summary and prospects of bio-inspired geotechnical engineering, offering fundamental insights for future research
Increased deficit of visual attention span with development in Chinese children with developmental dyslexia
No full textAbstractIt has been suggested that orthographic transparency and age changes may affect the relationship between visual attention span (VAS) deficit and reading difficulty. The present study explored the developmental trend of VAS in children with developmental dyslexia (DD) in Chinese, a logographic language with a deep orthography. Fifty-seven Chinese children with DD and fifty-four age-matched normal readers participated. The visual 1-back task was adopted to examine VAS. Phonological and morphological awareness tests, and reading tests in single-character and sentence levels were used for reading skill measurements. Results showed that only high graders with dyslexia exhibited lower accuracy than the controls in the VAS task, revealing an increased VAS deficit with development in the dyslexics. Moreover, the developmental trajectory analyses demonstrated that the dyslexics seemed to exhibit an atypical but not delayed pattern in their VAS development as compared to the controls. A correlation analysis indicated that VAS was only associated with morphological awareness for dyslexic readers in high grades. Further regression analysis showed that VAS skills and morphological awareness made separate and significant contributions to single-character reading for high grader with dyslexia. These findings suggested a developmental increasing trend in the relationship between VAS skills and reading (dis)ability in Chinese.</jats:p
