24 research outputs found
Enhanced electromagnetic microwave absorption of SiOC ceramics targeting the integration of structure and function
No full textThe electromagnetic waves (EMW) absorption properties of SiOC ceramics synthesized by polymer-derived
method were investigated, and additive manufacturing was employed to obtain the integration of structure
and functions. The presence of free carbon and β-SiC nanocrystallites increased the internal relaxation interfacial
polarization, which improved the EMW absorption properties significantly. In particular for the sample pyrolyzed
at 1200 ◦C, the effective absorption bandwidth (EAB, RL<-10 dB) and minimum reflection loss (RL)were
4.9 GHz (at a thickness of 1.58 mm) and -23.5 dB, respectively, indicating the excellent EMW absorption
properties of this SiOC material. In addition, we 3D printed two typical porous structures (a log-pile grid and a
gyroid) in which the thickness of solid element corresponded to the one providing optimal absorption. Additive
Manufacturing of designed structures will enable to improve and further optimize the selection and control of the
absorbing material in practical applications
Enhanced electromagnetic microwave absorption properties of SiCN(Fe) ceramics produced by additive manufacturing via in-situ reaction of ferrocene
No full textDu Feng Ou Shi: Analysis and Criticism of Cui Shu's Study of the Shijing
No full text[[abstract]]清朝乾嘉年間的崔述以《考信錄》奠定其在中國史學上的崇高地位，又以《讀風偶識》之作在經學史上佔有一席之地。崔述與姚際恆、方玉潤並稱清代獨立治《詩》三大家，姚、方二氏的《詩經通論》、《詩經原始》是《詩經》學史上的名著，兩書都是針對三百篇進行全面析解的《詩經》完整文本，崔述的《讀風偶識》則僅針對部分詩進行論述，卻也可以跟姚、方之書相提並論，足見其另有獨到之處。不過，胡適等人對於《讀風偶識》的評價委實過高，亦不需深信。本文考察《讀風偶識》的解《詩》動機與特質，檢查崔述對於《詩經》漢、宋之學的接受與批評，從而說明《讀風偶識》在《詩經》學史上的定位與意義。透過本文的論述，吾人可知，「以史觀詩，以詩興史」正是《讀風偶識》之最大特色，而崔述雖然強烈批評傳統《詩經》學，但傳統《詩》教的影響無遠弗屆，治學風格與方式特立獨行的崔述，其解《詩》依然在傳統的籠罩中。[[abstract]]The Qing dynasty scholar Cui Shu's崔述 work Kao xin lu考信錄 established his reputation in Chinese historiography, while he owes his position in the history of Confucian classics studies to another work, Du feng ou shi讀風偶識. Cui Shu, Yao Jiheng姚際恆 and Fang Yurun方玉潤 are known as the three great independent Qing scholars of the Shijing詩經. Yao's Shijing tong lun詩經通論and Fang's Shijing yuan shi詩經原始 are masterpieces of Shying studies, both works providing analysis and interpretation of the more than 300 poems that constitute the full-length text of the Shijing. Despite only discussing the Songs (feng風) from the Shijing, Cui Shu's Du feng ou shi is still held on a par with these works, serving to show that it is a work of great originality in its own right. However, it is not necessary to believe the excessive praise heaped on Du feng ou shi by scholars such as Hu Shi胡適. This paper identifies the motivations behind Cui Shu's interpretation of the poems in Du feng ou shi and its characteristics, examines his acceptance and criticism of Han and Song studies of the Shjjing, and so explains the position and significance of Du feng ou shi in the history of Shying scholarship. This paper shows that the most distinguishing feature of Du feng ou shi is that it "observes the Shijing from the point of view of historical studies, and promotes the value of historical studies through the Shying"以史觀詩,以詩興史. Although Cui Shu strongly criticizes traditional Shying studies, the influence of traditional Shijing teaching is deep and far-reaching. Indeed, Cui Shu's interpretation of the Shying is still unable to escape these traditional influences, despite his unique and independent style and methods of scholarship
Enhanced electromagnetic microwave absorption of Fe/C/SiCN composite ceramics targeting in integrated structure and function
No full textElectromagnetic and wave absorbing properties of Fe-doped polymer-derived SiCN ceramics
No full textFe-doped polymer-derived SiCN ceramics were synthesized by a precursor conversion method with different contents of nano-Fe2O3.</p
A box model test of the freshwater forcing hypothesis of abrupt climate change and the physics governing ocean stability
No full textAuthor Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 25 (2010): PA4222, doi:10.1029/2010PA001936.Observations and an ocean box model are combined in order to test the adequacy of the freshwater forcing hypothesis to explain abrupt climate change given the uncertainties in the parameterization of vertical buoyancy transport in the ocean. The combination is carried out using Bayesian stochastic inversion, which allows us to infer changes in the mass balance of Northern Hemisphere (NH) ice sheets and in the meridional transports of mass and heat in the Atlantic Ocean that would be required to explain Dansgaard-Oeschger Interstadials (DOIs) from 30 to 39 kyr B.P. The mean sea level changes implied by changes in NH ice sheet mass balance agree in amplitude and timing with reconstructions from the geologic record, which gives some support to the freshwater forcing hypothesis. The inversion suggests that the duration of the DOIs should be directly related to the growth of land ice. Our results are unaffected by uncertainties in the representation of vertical buoyancy transport in the ocean. However, the solutions are sensitive to assumptions about physical processes at polar latitudes.This material is based upon work supported
by the National Science Foundation under grant OCE‐0402363 and Department
of Energy grant DE‐FG02‐08ER64619
The influence of carbon materials on the absorption performance of polymer-derived SiCN ceramics in X-band
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