271 research outputs found
Tan tao Han dai yong yu ji wu zhi guan nian de zhuan bian
No full textDespite the fact that there has been an enormous amount of jades excavated from the Western Han tombs of Chu Princes, Xuzhou in Jiangsu province, little scholarly literature has been focused on these artefacts. Based on archaeological findings, this thesis selects some significant jade objects as the focus of attention, including jade pendants, jade vessels, jade weapons, jade suites and other burial jades. As the role and value of jade is varied in the hierarchy of material within different cultural and historical context, the changes in its functions and meanings, to some extent reflects the changes in politics, economy, and society. Through tracing their origins, the identity of the owners and examining the changes in material and society, this study attempts to reveal the cultural and social value embedded in these objects, and in doing so to reconstruct the changes in material concepts and aesthetic ideologies in the Han periods.On the basis of the achievements have hitherto in Han jade study, the present study is expected to shed light on our understanding of tomb culture and its relation to the society from a broader and more comprehensive perspective. Aside from placing specific types of jade into an accurate period or investigating their functions and sources, this study will read the object by cross reference to ancient textual material.Using jade, a particular category of art objects, as the point of entry, this study seeks to explore and question the issue of materiality and identity within the context of tomb art, and the wider issue of cultural and social practices in the Han Dynasty.林巧羚.Submitted: 2010年11月.Submitted: 2010 nian 11 yue.Adviser: Jenny F. So.Source: Dissertation Abstracts International, Volume: 73-04, Section: A, page: .Thesis (Ph.D.)--Chinese University of Hong Kong, 2011.Includes bibliographical references (p. 355-396).Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.Abstracts in Chinese and English.Lin Qiaoling
Exploring excitons in van der Waals heterostructures and their potential for lasing
No full textTwo-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) have gained intense attention in the field of optoelectronics and nanophotonics due to their unique excitonic properties. TMDs can act as efficient gain materials for lasing in combination with photonic cavities. Nanolasers based on TMDs have been extensively studied and offer promising prospects for energy-efficient lasers. Interlayer excitons (IXs) in type-II van der Waals heterostructures hold promise for energy efficient, silicon-integrated, tunable, and electrically pumped lasers. The moiré potentials formed in heterostructures create additional in-plane confinement on IXs, thus potentially providing large optical gain at low pumping levels. However, there is still a lack of research regarding the moiré exciton at room temperature, and the influence of moiré superlattices on laser performance remains unexplored. In this PhD project, we build a deterministic assembly system for transferring 2D materials. Starting with debugging an old spectrometer, we construct a multifunctional optical measurement setup working from the visible to the near-infrared (NIR) spectrum with high sensitivity. The success in platform construction serves as the cornerstone for our upcoming experiments. We fabricate high-quality MoS2/WSe2 heterobilayers and study the optical properties of excitons and their dependence on twist angles and pump power. We observe a significant energy shift (> 200 meV) of the IXs by varying twist angles. When the twist angle is close to zero, the IX resonance shows a notable blue-shift as we increase the pump power and the absorption peak of WSe2 A exciton splits. These observations indicate the existence of moiré excitons at room temperature. In addition, we study the impact of the moiré potential on the excitons by analyzing the time-resolved PL dynamics. We find that heterobilayers with strong interlayer coupling exhibit a lower IX energy and a longer IX lifetime than that with weak coupling. Our observation reveals that moiré excitons could be an efficient gain medium for energy-efficient and high-performance nanolasers. Furthermore, we couple moiré IXs to silicon topological cavities and study their light-matter interaction. We fabricate silicon high-Q cavities at DTU Nanolab and the hBN-encapsulated MoS2/WSe2 heterostructures are then transferred onto the photonic cavities by using our home-built transfer setup. By conducting powerdependent PL measurements, we observe low-threshold lasing-like emission in the optical fiber communication O-band (1260-1360 nm). Our device shows the highest spectral coherence (∼0.1 nm) compared to all 2D material laser systems and an impressive spontaneous-emission suppression ratio (SESR) of ∼10 dB, similar to the value achieved by the TMD-based vertical-cavity surface-emitting laser (VCSEL). Our works encourage studying novel exciton physics in moiré superlattices at room temperature and open new avenues for using these artificial quantum materials in high-performance device applications
Determining the number of factors in a multivariate error correction--volatility factor model
No full textIn order to describe the co-movements in both conditional mean and conditional variance of high dimensional non-stationary time series by dimension reduction, we introduce the conditional heteroscedasticity with factor structure to the error correction model (ECM). The new model is called the error correction--volatility factor model (EC--VF). Some specification and estimation approaches are developed. In particular, the determination of the number of factors is discussed. Our setting is general in the sense that we impose neither i.i.d. assumption on idiosyncratic components in the factor structure nor independence between factors and idiosyncratic errors. We illustrate the proposed approach with a Monte Carlo simulation and a real data example. Copyright The Author(s). Journal compilation Royal Economic Society 2008
Characteristics of ESD-Promoting Strategies in China’s Basic Education
No full text This article describes how education for sustainable development (ESD) has been integrated into education in China over the past decade through the efforts of the secretariat of a national steering committee working with UNESCO in conjunction with the UN Decade of Education for Sustainable Development. ESD is now part of a new national education plan in China. The author found six principal methods that successfully promoted ESD in China: (a) Using a theoretical framework as the driving force; (b) Public educational policies made on the basis of education research; (c) Regional educational reform that meets the needs of local sustainable development; (d) Curriculum teaching methods constituted with features of ESD; (e) ESD characteristics integrated in the physical plant of the campus; and (f) Chinese–foreign exchange and cooperation in ESD at various levels. </jats:p
Pathways to SO2 emissions reduction in China for 1995-2010: Based on decomposition analysis
No full textTo maintain sustained and rapid economic development will be China's strategic goals in a long time. Reducing pollution emission is an important means to coordinate economic development and environment. Identifying the main pathways of pollution reduction and analyzing their contributions has great significance to the pollution control strategies making. This article systematically identified the factors affecting pollution emissions of an open economy and analyzed how changes in pollution abatement, cleaner production, economic spatial structure and trade affect emissions based on decomposition analysis. Case study on China's SO2 emissions in 1995-2010 shows that: (i) on the national level, pollution abatement plays an increasingly significant role in pollution reduction. Cleaner production's contribution is instable, yet most years it declines the emissions. Economic spatial structure shows a positive contribution until 2006 it begins to increase emissions. International trade increases the domestic SO2 emissions in most of the years. (ii) On the regional level, pollution abatement is the most important factor reducing SO2 emissions for the eastern, middle and western China. Trade in the eastern region leads to pollution increase, while has an inverse contribution in the middle and western. The results yield important hints for China's pollution emission control policy making. (C) 2013 Elsevier Ltd. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000327686500036&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Environmental SciencesSCI(E)SSCI5ARTICLE,SI405-4153
Influence of solder condition on effective thermal conductivity of two-directional random fibres: Pore-scale simulation
No full textIt is indicated that the solder joint of the metal fibrous materials is a critical factor impacting the heat conduction. To reveal the mechanism by which solder joint sizes, solder joint skips, solder flux materials, and filling media affect the thermal conductivity of fibres, pore-scale numerical simulation is employed to study the thermal transport in two-directional (2-D) random fibres. Satisfactory agreement with existing data validates the numerical model. The dimensionless effective thermal conductivity (ETC) of the porous fibres increases with the solder joint sizes. As the solder joint size (i.e., solder joint ratio) increases by 3.06%, the in-plane (ke-in) and out-of-plane (ke-out) dimensionless ETC increase by 9.0% and 437.2%, respectively. However, the solder joint skips will weaken the thermal conductivity of the fibres. For the same fibre, the ETC of the fibre increases as the thermal conductivity of solders increases. Further, when the dissimilarity in thermal conductivity between the filling medium and the fibre is reduced, the fibre is less affected by the solder joint skips. Finally, it should be supplemented that the in-plane and out-of-plane ETC (ke-in and ke-out) of the fibre without any solder joint are reduced by an average of 14.3% and 98.8%, respectively.Process and Energ
Reexamine SO2 emissions embodied in China's exports using multiregional input-output analysis
No full textPrevious studies on embodied emission in China's exports focus on the national aggregate analysis while pay little attention to the interregional emission transfer driven by exports. We used multiregional input-output model of 30 provinces to reexamine the embodied emissions and to capture the interregional linkage in it. Results in 2002-2007 show that SO2 embodied in exports contributes 15.17-22.08% of the total domestic SO2 emissions, and 74.40-78.14% of the embodiment is in exports from the eastern provinces, where over 90% of China's exports occur. However, only about 70% of the embodied emission in eastern China's exports is discharged in the east; an increasing portion (24% to 34%) is released in the central and western provinces as a result of interregional production linkage. Moreover, the interregional connection becomes closer during the 2002-2007 period, which increases the scale and intensity of embodied emission in China's export given large gaps in emission intensity among regions. Further analysis on Guangdong, China's largest export province, shows that the SO2 emissions per unit of output induced by Guangdong's exports are larger than that induced by the province's own exports for most provinces, especially the central and western provinces which are restricted in exports and indirectly export by supporting Guangdong's exports via interregional economic linkage. The results yield important implications for China's export and pollution emission control policy. (C) 2015 Elsevier B.V. All rights reserved.National Natural Science Foundation of China [41471465, 71341028]; National Public Benefit Special Fund for Environmental Protection Research [201009001-4]; Chinese National 863 Program [2006AA06A309]SCI(E)[email protected]; [email protected]
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