210 research outputs found
Mechanical properties of multi-recycled aggregate concrete under combined compression and shear
No full textThe mechanical properties and strength failure criteria of natural aggregate concrete and multi-recycled aggregate concrete (multi-RAC) under combined compression and shear loading states are investigated in this study. The peak shear strength, peak shear displacement, and failure patterns are compared under different regeneration cycles and normal compressive stress ratios. The results reveal that both the peak shear strength and peak shear displacement increase with the increased normal stress ratio. The shear failure pattern with higher severity corresponds to more spalling powder and debris deposited on the shear fracture surface. When the regeneration cycles of coarse aggregate increase, the peak shear strength decreases and the descending trend become more evident with the higher vertical compressive stress ratio, whereas the peak shear displacement significantly fluctuates, regardless of the regeneration cycles and normal compressive stress ratios. Under the normal compressive stress, contact friction strength is the dominant component of peak shear strength in terms of cohesive strength, contact friction strength, and shear dilation strength. Based on different stress expressions, three compression-shear failure criterion models considering the regeneration cycles of coarse aggregate under planar stress state were established for RAC. The stress invariance failure criterion model and octahedral stress failure criterion model in quadratic parabolic functional forms can provide the high prediction accuracies.This is a manuscript of an article published as Lei, Bin, Hongchen Yu, Yipu Guo, Hanbing Zhao, Kejin Wang, and Wengui Li. "Mechanical properties of multi-recycled aggregate concrete under combined compression and shear." Engineering Failure Analysis 143, Part A (2023): 106910.
DOI: 10.1016/j.engfailanal.2022.106910.
Copyright 2022 Elsevier Ltd.
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0).
Posted with permission
Fracture behaviours of sustainable multi-recycled aggregate concrete under combined compression-shear loading
No full textThe mechanical properties and strength failure criteria of natural coarse aggregate and multiple recycled coarse aggregate concrete under the combined compression and shear loading states are investigated in this study. The failure pattern, peak shear strength, and peak shear displacement are compared in terms of the number of regeneration cycles and normal compressive stress ratios. The results reveal that both the peak shear strength and peak shear displacement of concrete increase with the enlarged normal stress ratio. The shear failure pattern with higher severity corresponds to more spalling powder and debris deposited on the shear fracture surface. When the times of coarse aggregate regeneration increase, the peak shear strength decreases, and the descending trend becomes more evident with the increased vertical compressive stress ratio, whereas the peak shear displacement significantly fluctuates, regardless of the regeneration time and the normal compressive stress ratios. With normal compressive stress, the contact friction strength becomes the dominated component of peak shear strength consisting of cohesive strength, contact friction strength, and shear dilation strength. Based on the different stress expressions, three compression-shear failure criterion models considering the times of coarse aggregate regeneration under planar stress state were established for concrete. Despite the strong correlation with the correlation factors (R2) larger than 0.96 for all the models, the failure criterion model based on stress invariance and failure criterion model based on octahedral stresses in the quadratic parabolic functional forms provides the highest predictive accuracy. The related outcomes are expected to fill the gap of the related research on recycled aggregate concrete.This is a manuscript of an article published as Lei, Bin, Hongchen Yu, Yipu Guo, Wenkui Dong, Rui Liang, Xiaonan Wang, Xuqun Lin, Kejin Wang, and Wengui Li. "Fracture behaviours of sustainable multi-recycled aggregate concrete under combined compression-shear loading." Journal of Building Engineering (2023): 106382.
DOI: 10.1016/j.jobe.2023.106382.
Copyright 2023 Elsevier Ltd.
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0).
Posted with permission
Liu Jishan xin xing lun tan wei: wei Mou Zongsan de "yi xin zhe xing" zuo bian hu
No full textM.Phil.In this thesis, I will focus on the discussion of Liu Jishan (Liu Zongzhou)’s theory of heart-mind and nature, based on the outcome of contemporary studies. The reason for investigating Liu’s theory is that he had developed a unique and complicated theory of heart-mind and nature based on the late Ming development of Confuciansim, which making him “The Last Neo-Confucian”. Due to the historical background and the complicity of his theory, Liu’s system is difficult to understand and opens for different interpretations. In my opinion, Mou Zongsan’s theory of “manifest nature by heart-mind” is the best interpretation to grasp Liu’s insight among the contemporary studies. Therefore, this thesis argues for Mou’s interpretation to Liu’s theory by analyzing Liu’s text and defending contemporary criticisms to Mou.This thesis includes four parts: First, it analyzes Liu’s problematic from the historical background of late Ming Confucian thoughts. Second, it illustrates Mou’s view in detail and explains why his interpretation fitting into Liu’s thought. Third, it analyzes the contemporary studies of Liu to see their understanding and criticisms to Mou. Finally, it defends for Mou’s view, by arguing Mou’s view grasping Liu’s insight by developing a system of covering both the subjective-moral aspect and the objective-ontological aspect, in order to solve the difficulties of moral practices caused by the School of Heart-mind.這篇論文的工作是在建基於當代研究的視野下，對明末大儒劉蕺山（宗周）的心性論作進一步的討論。以蕺山為研究對像的原因，是由於他在修正明末各種思潮的脈絡下發展出一套較為複雜的心性論系統。他在心性論上的創穫，使他獲得「宋明理學殿軍」之美譽。但亦因為蕺山在思想背景及其心性論系統上的複雜性，這使得他的系統艱澀難懂外，亦引不少詮釋上的爭議。而筆者認為，在當代研究之中，最能說明和闡發蕺山的心性論的洞見者當屬牟宗三的以心著性系統。故本文的目的在於疏解蕺山的心性論文字的同時論證牟宗三的以心著性是對蕺山最佳的解讀，並嘗試為牟宗三的觀點辯護，以回應當代學界的批評。為此，本篇論文主要處理四項工作：一、從明末思潮的脈絡梳理蕺山的問題意識。二、對牟宗三的以心著性觀點作出詳細的分析，並解釋此觀點何以契合蕺山的文字。三、分析當代蕺山研究中贊同及反對牟說的觀點，以說明當代學界對於以心著性的理解。四、為牟說作出辯護，論證以心著性系統以分言主觀道德面與客觀存有面的方式堵塞心學工夫的流弊是最能把握蕺山心性論洞見的說法。筆者希望著此來說明一套主客兼備的心性論系統在宋明理學中的哲學洞見。張鴻辰."2019年7月".Thesis M.Phil. Chinese University of Hong Kong 2019.Includes bibliographical references (leaves 246-256).Abstracts in Chinese and English.Title from PDF title page (viewed on February 23, 2022).Zhang Hongchen
SELF-HEALING FUNCTIONAL MATERIALS FOR INTELLIGENT ROBOTICS
No full textPh.DDOCTOR OF PHILOSOPHY (NUSGS
Trust-DETM: Distributed Energy Trading Model Based on Trusted Execution Environment
No full textThe traditional centralized power trading model suffers from high maintenance costs, low processing efficiency and unsynchronized information, and it cannot adapt to the high-frequency and small-dollar distributed energy trading scenario. To address the above issues, we propose Trust-DETM, a model for the implementation of distributed energy trading based on a trusted execution environment. First, we introduce a reputation metric mechanism and propose a transaction matching algorithm based on the reputation metric to achieve the accurate matching of transaction objects. Secondly, as the distributed energy trading model lacks an effective trust mechanism, we propose a commitment scheme based on smart contracts and a trusted execution environment to solve the trust problem between producers and consumers. Finally, we conduct a comprehensive experimental evaluation of the efficiency of Trust-DETM. Through comparative experiments, we find that Trust-DETM achieves trade matching and trusted execution in a lower simultaneous running time than comparable distributed trading models
Thermophilic and Halophilic Extremophiles in Eurasian Environments
No full textThis eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contac
Controlled synthesis of high performance carbon/zeolite T composite membrane materials for gas separation
No full textA simple approach has been developed to synthesize the carbon/zeolite T composite membrane materials with the high gas separation performance. The precursors of the composite membrane are composed of polyimide matrix and dispersed zeolite T particles. The composite membranes prepared by pyrolysis at 973 K show excellent gas (H2, CO2, O2, N2, and CH4) permeability and selectivity (O2/N2, CO2/CH4) for both single gas and mixed-gas. The gas separation performance of the composite membranes can be controlled in a wide range by only changing the zeolite T particle size. The maximum selectivity of O2 over N2 (21/79 mol%) for the composite membranes with the least zeolite T particle (0.5 μm) is 15 with an O2 permeability of 347 Barrers (1 Barrer = 7.5 × 10−18 m2 s−1 Pa−1) and the selectivity of CO2 over CH4 (50/50 mol%) reaches a value of 179 with a CO2 permeability of 1532 Barrers. It is believed that the increase of gas permeability is attributed to the ordered microchannels in the zeolite and the interfacial gaps formed between zeolite and carbon matrix in the composite membranes. And the gas selectivity is tuned by the size of interfacial gaps which are varied with the zeolite particle size. This technique will provide a simple and convenient route to efficiently improve the trade-off relationship between the permeability and the selectivity and enable the construction of carbon-based composite materials with novel functionalities in membrane science
Multiferroic CoFe2O4-BiFeO3 core-shell nanofibers and their nanoscale magnetoelectric coupling
No full textMultiferroic CoFe2O4-BiFeO3 (CFO-BFO) core-shell nanofibers were synthesized by coaxial electrospinning. The spinel structure of CFO and perovskite structure of BFO were confirmed by x-ray diffraction and high-resolution transmission electron microscopy. The core-shell configuration of nanofibers was verified by scanning electron microscopy and transmission electron microscopy images. The macroscopic ferromagnetic property of core-shell nanofibers was demonstrated by magnetic hysteresis loop. The local magnetoelectric (ME) coupling was confirmed by using dual frequency piezoresponse force microscopy (PFM) under an external magnetic field, showing magnetically induced evolution of piezoresponse and domain structure. The ferroelectric characteristics are demonstrated by the switching spectroscopy PFM. From PFM hysteresis and butterfly loops, it is observed that the piezoresponse amplitude is reduced while coercive voltage increased under external in-plane magnetic field, induced through the mechanical interactions between magnetostrictive CFO and piezoelectric BFO, from which the lateral ME coupling can be estimated quantitatively. The nanofibers thus can find a variety of applications as a one-dimensional multiferroic material
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