79 research outputs found
Isotopic constraints on the palaeoenvironmental conditions during the Cambrian radiation of animals
No full textDebates around the triggers for the Cambrian radiation have long focused on oxygenation events, weathering history and marine chemistry during the Ediacaran–Cambrian transition. However, high-resolution palaeoenvironmental constraints remain unsatisfactory regarding both long-term evolution and short-term shifts that directly tie into the early Cambrian fossil records and geological events. In the following thesis, a multi-proxy approach combining stratigraphic and geochemical analyses is presented that investigates the marine successions in Siberia and China, and draws on the environmental backdrop and triggers during the animal radiation events and Botomian–Toyonian extinction. This study miniaturises and validates the existing carbonate-associated sulphate (CAS) extraction methods, and suggests that a thorough leaching in NaCl solution reduces the risk of contamination from non-CAS sulphur phases. Applying high-fidelity geochemical methods and rigid screening techniques for diagenesis evaluation, this thesis presents paired, continuous and high-resolution carbonate carbon, CAS sulphur and carbonate strontium isotope trends for the Cambrian stages 2-4. These new data suggest that cyclical redox fluctuations exerted a direct control on the episodic pattern of early animal radiations, while low oceanic sulphate concentrations below modern levels likely persisted through the early Cambrian. High continental weathering flux may have dominated through Cambrian stages 2 and 3, implying high marine ion (e.g. Ca2+) and nutrient availability in the coeval oceans that could have facilitated animal diversification and calcium- favouring biomineralisation. This thesis also reports the first global seawater LOWESS- fitted 87Sr/86Sr curve from the latest Ediacaran to Cambrian Stage 4. New stratigraphic interpretations and detrital zircon ages provide the first robust constraints on the timing and position of the ‘Great Unconformity’ on the North China Craton (NCC). Provenance analysis further demonstrates the affinity between NCC and eastern Gondwana during the Cambrian Period
Design of a future drum kit
No full textAs one of the most popular musical instruments, drum kits' design has not changed a lot since it first emerged. However, the product contains some problems which significantly affect user experience. Not to improve the design, this project aims to dig deeper into the world of drum kit and drummers to identify their emotional values and related functional needs, hence to find new design possibilities for this classic musical instrument. Trend research, user research, and market research were conducted. The result was finalized into the fundamental emotion and related functional needs. The design vision was established, and the design was completed. The final design – Collector, is a conceptual drum kit with a new design language, which allows drummers to create their own sound library and is flexible to use in different scenarios. The design was evaluated with real drummers and was proved to be both practical and attractive. The concept shows enormous potential to be further developed into a commercial product.Integrated Product Desig
Maximizing gravitational acceleration measurement accuracy by tuning the interaction time between atoms and gravity
No full textCo-design for Multi-subsystem and Vehicle Routing-and-Control Problems
No full textCo-design refers to the process of integrating optimization of the physical design with a controller for a system. The challenge in co-design is that the optimization is simultaneously applied to both static/time-invariant (e.g., physical plant design) variables and dynamic/time-variant (e.g., state and control) variables, which can be coupled with each other.
The objective of this dissertation is to explore new formulations and approaches in co-design for multi-subsystem and vehicle routing-and-control problems. Specifically, four research questions are considered and resolved. In Research Question 1 (RQ1), the critical issue is how to formulate a class of multi-subsystem co-design problems with convex physical design subproblems and linear quadratic regulator control subproblems, and construct a decentralized solution approach for such problems. In Research Question 2 (RQ2), solution methods for a broader class of multi-subsystem co-design problems than those considered in RQ1 are investigated. In Research Question 3 (RQ3), the question is whether, in the context of co-design, the combined routing and control costs of a fleet of vehicles can be improved if optimal control is introduced into the routing. Finally, an extension of RQ3 is considered in Research Question 4 (RQ4), where the possibility of constructing an integrated vehicle routing-and-control problem with load-dependent dynamics is investigated.
Beyond the articles published by the author of this dissertation, the proposed research questions, models and methods presented have not been considered elsewhere in the literature
Modeling and Validation of Common-Mode Emission in Silicon Carbide Based Voltage Source Converters
No full textElectromagnetic compatibility (EMC) issues have become one of the most difficult challenges in power converter designs. With the invention of wide bandgap (WBG) power semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) power MOSFETs, the power converter designs are provided with the potential to be significantly more power dense than older generation converters using silicone IGBTs. However, the majority of spectral contents of the switching waveforms are moved from the very-low-frequency (VLF, 3 kHz to 30 kHz) range to low-frequency and up to the very-high-frequency (VHF, 30 MHz to 300 MHz) range. Moreover, due to the design traits of WBG-based converters, common-mode (CM) emission dominates the EMC problems. Conventional electromagnetic interference (EMI) modeling methodologies in the frequency range in and above VHF were mostly developed for applications where the power level is relatively low. For high-power and highly power-dense applications, new EMI modeling methodologies, especially in CM, need to be developed to allow more accurate analysis, more efficient design processes, and more optimal designs.
This doctoral dissertation documents the author\u27s development of a novel CM emission modeling methodology with a set of CM model segments that form canonical SiC-based voltage source converters and the surrounding electrical environment, such as filter structures. The accuracy of all these model segments is validated with two applicational scenarios at frequencies up to 30 MHz. These modulized building blocks and the methodology using these blocks to construct full converter system CM models are lightweight and insightful, thus enabling more optimal design processes for SiC-enabled high-voltage and high-power-density converters such as virtual prototyping processes and multi-objective optimization. Furthermore, the discoveries of this dissertation will help power electronics designers to understand better the potential and challenges of the utilization of SiC semiconductors in voltage source converters
Carbonate-platform response to the Toarcian Oceanic Anoxic Event in the southern hemisphere : Implications for climatic change and biotic platform demise
No full textWe are grateful to Zhifei Liu for TOC and analyses at the Tongji University. We thank also Wei An, Bo Zhou and Shiyi Li for their assistance in the field, and Zhicheng Huang, Yiwei Xu and Weiwei Xue for their help in the laboratory, and Chao Chang, Tianchen He and Bolin Zhang for their helpful discussion. Hugh Jenkyns commented on a draft of the manuscript. We would also like to thank Editor Derek Vance, Christopher Pearce and two anonymous reviewers whose comments greatly improved the manuscript. This study was financially supported by the National Natural Science Funds for Distinguished Young Scholar in China (41525007) and the Chinese MOST 973 Project (2012CB822001). DBK acknowledges support of NERC Fellowship NE/I02089X/1. This is a contribution to the IGCP 655.Peer reviewe
范晔《后汉书》选录文章研究 = A study of literary works selected by Fan Ye’s book of the Eastern Han
No full text范晔《后汉书》作为前四史之一，除了富有很高的史学价值外，同时富有很高的文学价值，很多东汉的文章都赖以保全。本文以范晔《后汉书》中所选录的文章（以文为主，兼以诗赋）为基础，探讨东汉文学的变迁。第一章按照文体不同，将范晔《后汉书》所选录的文章分类总结，发现散文中语言越来越重视彰显文采，表现情志，而韵文也多与政事、时事挂钩，体现出比较强烈的应用文的功用，可见东汉仍然是以文章的实用性作为首要目的。另一方面，自和帝起，宦戚之争日趋激烈，使得深受其害的文人不得不做出选择，一则慷慨激昂，针砭时弊，一则远离朝局，怡然自得。范晔《后汉书》首次于正史之中设立《文苑传》，意义十分深远，但诸如班固、张衡、孔融等文人却未被收录，难免给人以《文苑传》中不录一流作家的误解。第二章便以《文苑传》传主为研究对象，将这些文人按其成就分为四类，并分析其中如杜笃、赵壹、傅毅、郦炎、崔琦、祢衡等一流文章家在《文苑传》中的作品、传记，说明他们在文学史上的杰出成就。第三章着眼于《文苑传》以外的杰出文章家，分为从班固到张衡、从王符到仲长统、从蔡邕到孔融三条线索，通过前两条线索讨论在东汉由盛至衰的变迁下，文章的嬗变，兼及范晔《后汉书》选录文章的标准，最后一条线索主要讨论东汉末期文章的发展，可以看出“慷慨以任气，磊落以使才”的文学风格在“建安风骨”之前就已初现端倪。第四章以解构建安七子为引线，从建安风骨与建安文学之间关系展开讨论，继而讨论文学史上多层次的遮蔽与错位现象，并对文学自觉说提出自己的看法，即文学自觉是一个过程，从而得出东汉文学是从汉代醇厚到魏晋壮节之间不可缺少的重要一环，而非西汉文学之附庸。As one of the Early Four Historiographies, which well-preserved lots of literary works, Fan Ye’s Book of the Eastern Han not only has a great historical value, but also has a great literary value. Based on the study of literary works (mainly prose, and extend to rhapsody and poetry) selected by Fan Ye, this thesis aims to discuss the literature development during the Eastern Han dynasty.
First chapter studies the literary works selected by Fan Ye according to different genres. It finds out that during Eastern Han dynasty, proses and rhymes were closely related, more rhetorical and lexical skills were used in composing proses with personal feeling, while rhymes were most likely related to political issues. From the succession of Emperor He onwards, subsequent reigns were increasingly marked by eunuch intervention in court politics and their involvement in the violent power struggles of the imperial consort clans. Scholars had to choose either staying in the court - their literary works became more vigorous, or leaving the court - their literary works became more speculative.
It is a remarkable breakthrough that Fan Ye introduced “Biographies of Writers” in the historiography, yet many famous litterateurs such as Ban Gu, Zhang Heng, Kong Rong, etc. were not in this biography, which left us an impression that those litterateurs in “Biographies of Writers” were noteless. Chapter two categorizes the litterateurs in “Biographies of Writers” into four groups, and focuses on first-class litterateurs, such as DU Du, ZHAO Yi, FU Yi, LI Yan, CUI Qi, MI Heng, etc., to discuss their great contributions to the literature.
On the other hand, chapter three focuses on three pairs of famous litterateurs who are not selected in “Biographies of Writers”, BAN Gu and ZHANG Heng, WANG Fu and ZHONG Changtong, CAI Yong and KONG Rong. Through the studies on first two pairs of litterateurs, the chapter aims to discuss the literature transition during the Eastern Han dynasty, as well as Fan Ye’s preferences of selecting literary works. While the last pair of litterateurs CAI Yong and KONG Rong, shows the inkling of “the vigorous and powerful style of Jian'an literature” was found earlier than the Jian'an Period.
Chapter four starts with the deconstruction of the term “Seven Scholars of Jian'an”, followed by the discussion of the relationship between “Jian'an Fenggu” and “Jian'an Literature”, thus to discuss about the “Concealment” and “Dislocation” phenomenon in literature studies. Last but not least, together with the discussion on the time literature entered conscientious era, shows that the literature of the Eastern Han has an irreplaceable and unique value during the transition period from Han to WeiJin.Master of Art
范晔《后汉书》选录文章研究 = A study of literary works selected by Fan Ye’s book of the Eastern Han
No full text范晔《后汉书》作为前四史之一，除了富有很高的史学价值外，同时富有很高的文学价值，很多东汉的文章都赖以保全。本文以范晔《后汉书》中所选录的文章（以文为主，兼以诗赋）为基础，探讨东汉文学的变迁。第一章按照文体不同，将范晔《后汉书》所选录的文章分类总结，发现散文中语言越来越重视彰显文采，表现情志，而韵文也多与政事、时事挂钩，体现出比较强烈的应用文的功用，可见东汉仍然是以文章的实用性作为首要目的。另一方面，自和帝起，宦戚之争日趋激烈，使得深受其害的文人不得不做出选择，一则慷慨激昂，针砭时弊，一则远离朝局，怡然自得。范晔《后汉书》首次于正史之中设立《文苑传》，意义十分深远，但诸如班固、张衡、孔融等文人却未被收录，难免给人以《文苑传》中不录一流作家的误解。第二章便以《文苑传》传主为研究对象，将这些文人按其成就分为四类，并分析其中如杜笃、赵壹、傅毅、郦炎、崔琦、祢衡等一流文章家在《文苑传》中的作品、传记，说明他们在文学史上的杰出成就。第三章着眼于《文苑传》以外的杰出文章家，分为从班固到张衡、从王符到仲长统、从蔡邕到孔融三条线索，通过前两条线索讨论在东汉由盛至衰的变迁下，文章的嬗变，兼及范晔《后汉书》选录文章的标准，最后一条线索主要讨论东汉末期文章的发展，可以看出“慷慨以任气，磊落以使才”的文学风格在“建安风骨”之前就已初现端倪。第四章以解构建安七子为引线，从建安风骨与建安文学之间关系展开讨论，继而讨论文学史上多层次的遮蔽与错位现象，并对文学自觉说提出自己的看法，即文学自觉是一个过程，从而得出东汉文学是从汉代醇厚到魏晋壮节之间不可缺少的重要一环，而非西汉文学之附庸。As one of the Early Four Historiographies, which well-preserved lots of literary works, Fan Ye’s Book of the Eastern Han not only has a great historical value, but also has a great literary value. Based on the study of literary works (mainly prose, and extend to rhapsody and poetry) selected by Fan Ye, this thesis aims to discuss the literature development during the Eastern Han dynasty.
First chapter studies the literary works selected by Fan Ye according to different genres. It finds out that during Eastern Han dynasty, proses and rhymes were closely related, more rhetorical and lexical skills were used in composing proses with personal feeling, while rhymes were most likely related to political issues. From the succession of Emperor He onwards, subsequent reigns were increasingly marked by eunuch intervention in court politics and their involvement in the violent power struggles of the imperial consort clans. Scholars had to choose either staying in the court - their literary works became more vigorous, or leaving the court - their literary works became more speculative.
It is a remarkable breakthrough that Fan Ye introduced “Biographies of Writers” in the historiography, yet many famous litterateurs such as Ban Gu, Zhang Heng, Kong Rong, etc. were not in this biography, which left us an impression that those litterateurs in “Biographies of Writers” were noteless. Chapter two categorizes the litterateurs in “Biographies of Writers” into four groups, and focuses on first-class litterateurs, such as DU Du, ZHAO Yi, FU Yi, LI Yan, CUI Qi, MI Heng, etc., to discuss their great contributions to the literature.
On the other hand, chapter three focuses on three pairs of famous litterateurs who are not selected in “Biographies of Writers”, BAN Gu and ZHANG Heng, WANG Fu and ZHONG Changtong, CAI Yong and KONG Rong. Through the studies on first two pairs of litterateurs, the chapter aims to discuss the literature transition during the Eastern Han dynasty, as well as Fan Ye’s preferences of selecting literary works. While the last pair of litterateurs CAI Yong and KONG Rong, shows the inkling of “the vigorous and powerful style of Jian'an literature” was found earlier than the Jian'an Period.
Chapter four starts with the deconstruction of the term “Seven Scholars of Jian'an”, followed by the discussion of the relationship between “Jian'an Fenggu” and “Jian'an Literature”, thus to discuss about the “Concealment” and “Dislocation” phenomenon in literature studies. Last but not least, together with the discussion on the time literature entered conscientious era, shows that the literature of the Eastern Han has an irreplaceable and unique value during the transition period from Han to WeiJin.Master of Art
Heritage Words: Exploring Port City Terms
No full textMaritime heritage structures, such as cranes or warehouses, are typical for historical port cities around the world and many of them have received recognition as having Outstanding Universal Value (OUV) and have been listed as UNESCO World Heritage sites. They have often been preserved and revitalized as expressions of former shipping networks and urban power after containerization in the 1960s when modern ports moved out of their historic inner-city locations to urban peripheries. To learn more about the conceptualization of port heritage as part of global flows and local urban systems, we manually checked 1121 abstracts of world heritage sites published on the UNESCO World Heritage Centre website 1, exploring a group of words describing the typology of buildings and structures associated with port functions and activities. We found 107 World Heritage Sites (out of 1121) related to port cities. By analysing the abstracts of the 107 sites, the authors established a series of findings. Firstly, the concepts of port city and port heritage reflected in the abstracts do not align with the definitions given by encyclopaedias or by people interested in port city research. The texts placed on the UNESCO World Heritage Centre website mainly focus on specific heritage types and values, rather than the bigger picture of maritime-related structures. Secondly, the listed port heritage sites appear to emphasize three port city functions: maritime trade, defence and colonial practices. Other functions that include housing, leisure or religion are rarely mentioned in the abstracts. Thirdly, since port cities are places where sea meets the land, nature meets human settlements, they should stress the nature-culture connection. Yet, the listed world heritage sites present a culture-nature dichotomy in the testified OUV. Vol. 4 No. 2 (2021): Port City Cultures, Values, or Maritime Mindsets, Part 2: Studying and Shaping Cultures in Port City Territories / Main SectionHistory, Form & Aesthetic
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