Privacy-preservation and effective auditing are two desirable but challenging requirements on distributed ledgers. To meet the requirements, this paper presents an auditing scheme, called as AudiTEE, which can audit a...Privacy-preservation and effective auditing are two desirable but challenging requirements on distributed ledgers. To meet the requirements, this paper presents an auditing scheme, called as AudiTEE, which can audit a distributed ledger in a generic, efficient, and privacy-preserving manner. AudiTEE leverages Trusted Execution Environment (TEE) to generate confidential but auditable transactions and realize arbitrary, efficient and confidential audit on them. Unfortunately, TEE suffers from some inherent barriers and is itself not a complete solution for fast audit. To tackle these challenges, AudiTEE takes advantage of KAMT (K-anonymity Authentication Based on Merkle Tree) protocol for efficient management on account and user-defined anonymous transactions. Further, to achieve a complete and fast audit with <i>unlinkability</i>, TEE doesn’t process through all but only a comparatively small part of transactions according to a special <i>ktag</i> attached on each transaction to ensure that a user cannot hide transactions from auditor even when auditor is blind with who is involved in each transaction on the ledger. Apart from the above, AudiTEE allows flexible control on user behaviors. We implement a concrete instance of AudiTEE under a bank setting and demonstrate the scalability with all its core functionalities.展开更多
新中国成立以来,我国已开展了大量陆生脊椎动物的本底调查和多样性研究项目,取得了一系列成果,并有学者针对兽类、鸟类和两栖爬行类的野外调查监测进行了总结和展望,但尚缺乏对所有陆生脊椎动物类群的调查历史和现状的分析及基于文献收...新中国成立以来,我国已开展了大量陆生脊椎动物的本底调查和多样性研究项目,取得了一系列成果,并有学者针对兽类、鸟类和两栖爬行类的野外调查监测进行了总结和展望,但尚缺乏对所有陆生脊椎动物类群的调查历史和现状的分析及基于文献收集的研究,特别是对调查方法和技术手段的对比与总结。因此,本文通过文献收集的方法,基于中国知网、Web of Science核心合集和以图书检索为主的读秀学术搜索,以“兽类”“鸟类”“爬行类”“两栖类”“动物资源”“调查”“监测”“新种”“新记录”和“物种多样性”作为检索词,检索并筛选了与兽类、鸟类、爬行类及两栖类陆生脊椎动物调查相关的文献资料共3,504篇,对陆生脊椎动物调查的研究文献在全国各省级行政区、生物多样性热点地区的分布,及其运用的调查方法和技术手段进行了系统的分析和比较。结果表明:相较兽类和两栖爬行类的调查,我国鸟类多样性的调查最多,发表文献占所有文献的70.26%。四川、云南的陆生脊椎动物调查最多,分别发表285篇、260篇文献。分布于我国的4个全球生物多样性热点地区的调查强度存在显著差异,印缅生物多样性热点地区和中国西南山地的研究文献较多,分别为348篇、324篇文献;中亚山地、喜马拉雅山地的研究文献较少,分别为71篇、66篇文献。陆生脊椎动物调查方法主要采用样线法、样点法、样方法和直接计数法,或将上述几种方法综合应用,样线法在所有场景(如:高山冻原、农田、城市等)中应用频率最高;技术手段以直接观察法、采集法、红外相机陷阱法为主,其中直接观察法在所有场景(如城市、湿地、草原等)中应用频率最高。当前,我国陆生脊椎动物调查已取得很多新进展,包括新兴物种采集和物种识别技术的发展(如无人机技术在大型兽类和集群水鸟上的应用、卫星追踪在迁徙鸟类上的应用等)、大数据时代下调查方法的改善和数据管理的提升等。未来我国的陆生脊椎动物调查,应拓宽新兴物种采集方法和识别技术的应用范围,进一步关注和发掘脊椎动物的新调查技术,以大数据为基础完善种群数据分析与调查管理体系,并朝着面向大众、服务社会的方向发展,以引起全社会对生物多样性保护的重视。本文以整体的视角概述了陆生脊椎动物各类群调查的情况,评估了不同地区调查强度的差异,并在调查方法和技术手段方面作了总结和展望,可为未来国内陆生脊椎动物野外调查工作的总体方向、调查侧重、方法运用等方面提供一定的参考。展开更多
SiBN ceramics are widely considered to be the most promising material for microwavetransparent applications in harsh environments owing to its excellent thermal stability and low dielectric constant.This work focuses ...SiBN ceramics are widely considered to be the most promising material for microwavetransparent applications in harsh environments owing to its excellent thermal stability and low dielectric constant.This work focuses on the synthesis and ceramization of single-source precursors for the preparation of SiBN ceramics as well as the investigation of the corresponding microstructural evolution at high temperatures including molecular dynamic simulations.Carbon-and chlorine-free perhydropolysilazanes were reacted with borane dimethyl sulfide complex at different molar ratios to synthesize single-source precursors,which were subsequently pyrolyzed and annealed under N2 atmosphere(without ammonolysis)to prepare SiBN ceramics at 1100,1200,and 1300℃with high ceramic yield in contrast to previously widely-used ammonolysis synthesis process.The obtained amorphous SiBN ceramics were shown to have remarkably improved thermal stability and oxidation resistance compared to amorphous silicon nitride.Particularly,the experimental results have been combined with molecular dynamics simulation to further study the amorphous structure of SiBN and the atomic-scale diffusion behavior of Si,B,and N at 1300℃.Incorporation of boron into the Si–N network is found to suppress the crystallization of the formed amorphous silicon nitride and hence improves its thermal stability in N2 atmosphere.展开更多
文摘Privacy-preservation and effective auditing are two desirable but challenging requirements on distributed ledgers. To meet the requirements, this paper presents an auditing scheme, called as AudiTEE, which can audit a distributed ledger in a generic, efficient, and privacy-preserving manner. AudiTEE leverages Trusted Execution Environment (TEE) to generate confidential but auditable transactions and realize arbitrary, efficient and confidential audit on them. Unfortunately, TEE suffers from some inherent barriers and is itself not a complete solution for fast audit. To tackle these challenges, AudiTEE takes advantage of KAMT (K-anonymity Authentication Based on Merkle Tree) protocol for efficient management on account and user-defined anonymous transactions. Further, to achieve a complete and fast audit with <i>unlinkability</i>, TEE doesn’t process through all but only a comparatively small part of transactions according to a special <i>ktag</i> attached on each transaction to ensure that a user cannot hide transactions from auditor even when auditor is blind with who is involved in each transaction on the ledger. Apart from the above, AudiTEE allows flexible control on user behaviors. We implement a concrete instance of AudiTEE under a bank setting and demonstrate the scalability with all its core functionalities.
文摘新中国成立以来,我国已开展了大量陆生脊椎动物的本底调查和多样性研究项目,取得了一系列成果,并有学者针对兽类、鸟类和两栖爬行类的野外调查监测进行了总结和展望,但尚缺乏对所有陆生脊椎动物类群的调查历史和现状的分析及基于文献收集的研究,特别是对调查方法和技术手段的对比与总结。因此,本文通过文献收集的方法,基于中国知网、Web of Science核心合集和以图书检索为主的读秀学术搜索,以“兽类”“鸟类”“爬行类”“两栖类”“动物资源”“调查”“监测”“新种”“新记录”和“物种多样性”作为检索词,检索并筛选了与兽类、鸟类、爬行类及两栖类陆生脊椎动物调查相关的文献资料共3,504篇,对陆生脊椎动物调查的研究文献在全国各省级行政区、生物多样性热点地区的分布,及其运用的调查方法和技术手段进行了系统的分析和比较。结果表明:相较兽类和两栖爬行类的调查,我国鸟类多样性的调查最多,发表文献占所有文献的70.26%。四川、云南的陆生脊椎动物调查最多,分别发表285篇、260篇文献。分布于我国的4个全球生物多样性热点地区的调查强度存在显著差异,印缅生物多样性热点地区和中国西南山地的研究文献较多,分别为348篇、324篇文献;中亚山地、喜马拉雅山地的研究文献较少,分别为71篇、66篇文献。陆生脊椎动物调查方法主要采用样线法、样点法、样方法和直接计数法,或将上述几种方法综合应用,样线法在所有场景(如:高山冻原、农田、城市等)中应用频率最高;技术手段以直接观察法、采集法、红外相机陷阱法为主,其中直接观察法在所有场景(如城市、湿地、草原等)中应用频率最高。当前,我国陆生脊椎动物调查已取得很多新进展,包括新兴物种采集和物种识别技术的发展(如无人机技术在大型兽类和集群水鸟上的应用、卫星追踪在迁徙鸟类上的应用等)、大数据时代下调查方法的改善和数据管理的提升等。未来我国的陆生脊椎动物调查,应拓宽新兴物种采集方法和识别技术的应用范围,进一步关注和发掘脊椎动物的新调查技术,以大数据为基础完善种群数据分析与调查管理体系,并朝着面向大众、服务社会的方向发展,以引起全社会对生物多样性保护的重视。本文以整体的视角概述了陆生脊椎动物各类群调查的情况,评估了不同地区调查强度的差异,并在调查方法和技术手段方面作了总结和展望,可为未来国内陆生脊椎动物野外调查工作的总体方向、调查侧重、方法运用等方面提供一定的参考。
基金The authors would like to acknowledge Merck KGaA for the financial support of this research project.Wei Li acknowledges financial support from China Scholarship Council(No.201907040060)during his research at TU Darmstadt.Zhenghao Wu acknowledges the funding of Deutsche Forschungsgemeinschaft via the SFB-TRR 146“Multiscale Simulation Methods for Soft Matter Systems”,Project A8.
文摘SiBN ceramics are widely considered to be the most promising material for microwavetransparent applications in harsh environments owing to its excellent thermal stability and low dielectric constant.This work focuses on the synthesis and ceramization of single-source precursors for the preparation of SiBN ceramics as well as the investigation of the corresponding microstructural evolution at high temperatures including molecular dynamic simulations.Carbon-and chlorine-free perhydropolysilazanes were reacted with borane dimethyl sulfide complex at different molar ratios to synthesize single-source precursors,which were subsequently pyrolyzed and annealed under N2 atmosphere(without ammonolysis)to prepare SiBN ceramics at 1100,1200,and 1300℃with high ceramic yield in contrast to previously widely-used ammonolysis synthesis process.The obtained amorphous SiBN ceramics were shown to have remarkably improved thermal stability and oxidation resistance compared to amorphous silicon nitride.Particularly,the experimental results have been combined with molecular dynamics simulation to further study the amorphous structure of SiBN and the atomic-scale diffusion behavior of Si,B,and N at 1300℃.Incorporation of boron into the Si–N network is found to suppress the crystallization of the formed amorphous silicon nitride and hence improves its thermal stability in N2 atmosphere.
