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Highly elastic 2D covalent organic framework films of interwoven single crystals

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National Science Review 2024年第7期11卷 71-72页

作者： Tongwen xu Key Laboratory of Precision and Intelligent Chemistry Department of Applied ChemistrySchool of Chemistry and Materials ScienceUniversity of Science and Technology of China

Two-dimensional(2D) materials feature angstrom-scale pores and tunable pore chemistry, demonstrating great potential for applications including flexible electronics and *** ion/molecule transport in the sub-nanometer-sized pore confinement often reveals phenomena not seen in bulk materials [1]. Yet, the practical application of 2D materials is hindered by their poor mechanical properties.

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Biohythane production from two-stage anaerobic digestion of food waste:A review

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Journal of Environmental Sciences 2024年第5期139卷 334-349页

作者： Xiaona An Ying xu Xiaohu Dai State Key Laboratory of Pollution Control and Resource Reuse School of Environmental Science and EngineeringTongji UniversityShanghai 200092China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China

The biotransformation of food waste(FW)to bioenergy has attracted considerable research attention as a means to address the energy crisis and waste disposal *** this end,a promising technique is two-stage anaerobic digestion(TSAD),in which the FW is transformed to biohythane,a gaseous mixture of biomethane and *** review summarises the main characteristics of FW and describes the basic principle of ***,the factors influencing the TSAD performance are identified,and an overview of the research status;economic aspects;and strategies such as pre-treatment,co-digestion,and regulation of microbial consortia to increase the biohythane yield from TSAD is ***,the challenges and future considerations associated with the treatment of FW by TSAD are *** paper can provide valuable reference for the improvement and widespread implementation of TSAD-based FW treatment.

关键词： Two-stage anaerobic digestion(TSAD) Food waste(FW) Methane production Hydrogen production

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HIV抗体检测策略的临床验证结果分析

中国艾滋病性病 2019年第8期25卷 783-786页

作者：余明许文平孔丹邹家凤泸州市疾病预防控制中心

目的针对《全国艾滋病检测技术规范》(2015年修订版)中的临床诊断的抗体检测策略进行验证,证明'抗体确证试验'作为补充试验时存在局限性,对处于早期感染样本的检测有漏检风险方法对2017年6月至2018年5月期间,本实验室抗体确证试验结果为... 详细信息

目的针对《全国艾滋病检测技术规范》(2015年修订版)中的临床诊断的抗体检测策略进行验证,证明'抗体确证试验'作为补充试验时存在局限性,对处于早期感染样本的检测有漏检风险方法对2017年6月至2018年5月期间,本实验室抗体确证试验结果为'HIV抗体阴性'的160份样本,用灵敏度略高的抗体试剂进行复检,按复检结果报告,并对两次检测结果不一致的样本进行核酸检测。结果 160份样本中40份复检为'HIV-1抗体不确定',无'HIV-1抗体阳性',进行核酸检测的样本17/40结果>5 000拷贝/mL,2/40结果<5 000拷贝/mL,21/40未检出。收集到17份随访复查结果,其中11份'HIV-1抗体阳性',4份'HIV抗体阴性',2份'HIV-1抗体不确定'。结论抗体确证试验检测为'HIV抗体阴性'的样本,不能直接排除HIV感染,建议对'HIV抗体阴性'样本进行区别分析,有必要时进行随访复查或核酸检测。

关键词：艾滋病病毒早期感染抗体确证试验漏检随访复查核酸检测

A stable staggered-grid finite-difference scheme for acoustic modeling beyond conventional stability limit

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Petroleum Science 2024年第1期21卷 182-194页

作者： Jing-Yi xu Yang Liu National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing 102249China China University of Petroleum(Beijing) Karamay CampusKaramay 834000XinjiangChina

Staggered-grid finite-difference(SGFD)schemes have been widely used in acoustic wave modeling for geophysical *** improved methods are proposed to enhance the accuracy of numerical ***,these methods are inevitably limited by the maximum Courant-Friedrichs-Lewy(CFL)numbers,making them unstable when modeling with large time sampling intervals or small grid *** solve this problem,we extend a stable SGFD scheme by controlling SGFD dispersion relations and maximizing the maximum CFL ***,to improve modeling stability,we minimize the error between the FD dispersion relation and the exact relation in the given wave-number region,and make the FD dispersion approach a given function outside the given wave-number area,thus breaking the conventional limits of the maximum CFL ***,to obtain high modeling accuracy,we use the SGFD scheme based on the Remez algorithm to compute the FD *** addition,the hybrid absorbing boundary condition is adopted to suppress boundary reflections and we find a suitable weighting coefficient for the proposed *** derivation and numerical modeling demonstrate that the proposed scheme can maintain high accuracy in the modeling process and the value of the maximum CFL number of the proposed scheme can exceed that of the conventional SGFD scheme when adopting a small maximum effective wavenumber,indicating that the proposed scheme improves stability during the modeling.

关键词： Acoustic wave Staggered-grid finite-difference(SGFD) modeling Courant-friedrichs-lewy(CFL)number Stability

Comparison of Microwave Imaging Algorithms for Short-Range Scenarios

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Journal of Beijing Institute of Technology 2024年第3期33卷 227-236页

作者： Zhengyue Dong Ning xu Kuiwen xu Engineering Research Center of Smart Microsensors and Microsystems Ministry of EducationHangzhou Dianzi UniversityHangzhou 310018China

Three dimensional(3-D)imaging algorithms with irregular planar multiple-input-multiple-output(MIMO)arrays are discussed and compared with each *** on the same MIMO array,a modified back projection algorithm(MBPA)is accordingly proposed and four imaging algorithms are used for comparison,back-projection method(BP),back-projection one in time domain(BP-TD),modified back-projection one and fast Fourier transform(FFT)-based MIMO range migration algorithm(FFT-based MIMO RMA).All of the algorithms have been implemented in practical application scenarios by use of the proposed imaging *** to the practical applications,MIMO array-based imaging system with wide-bandwidth properties provides an efficient tool to detect objects hidden behind a *** MIMO imaging radar system,composed of a vector network analyzer(VNA),a set of switches,and an array of Vivaldi antennas,have been designed,fabricated,and ***,these algorithms have been applied to measured data collected in different scenarios constituted by five metallic spheres in the absence and in the presence of a wall between the antennas and the targets in simulation and pliers in free space for experimental ***,the focusing properties and time consumption of the above algorithms are compared.

关键词： multiple-input-multiple-output(MIMO) short-range imaging back projection modi-fied back propagation range migration algorithm(RMA) through-wall imaging

Formation estimation and evolution mechanism of the pressure arch for non-circular tunnels under asymmetrical stress field

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Science China(Technological Sciences) 2024年第9期67卷 2919-2938页

作者： SUN ZhenYu ZHANG DingLi xu Tong CHEN xu Key Laboratory for Urban Underground Engineering of Ministry of Education Beijing Jiaotong UniversityBeijing 100044China

The tunneling-induced stress redistribution is dependent on the tunnel shape and the in-situ stress field, and the previous arch characterization method based on the circumferential or maximum principal stresses is only suitable for the circular tunnels under the hydrostatic stress field. In this study, a unified characterization method of the pressure arch for non-circular tunnels under the arbitrary stress field is proposed. By comparing the variations of compressive stress in different directions due to excavation, the ratio of the most significant increase in compressive stress is presented to characterize the arch effect, and the corresponding numerical algorithm is given. Since the proposed method takes the stress element as the basic analytical model, it can be easily applied to various complex excavation situations. Thereafter, combined with the established folding catastrophic model, an objective and unified quantitative method of the pressure arch boundaries is given. Using the proposed method, the longitudinal evolution of the pressure arch is analyzed. According to the expansion rate of the arch boundaries, three evolution stages including the initial formation, rapid expansion and stabilization are categorized. Parametric studies are conducted to illustrate the effect of ground properties and support stiffness on the pressure arch formation. It is found that the ground strength parameters and burial depth affect the arch range at a decreasing rate, while they have little effect on the arch shape. The lateral pressure coefficient has a significant effect on both the shape and range of the pressure arch. Increasing the support stiffness helps reduce the pressure arch range with a decreasing rate, while the synchronous variation of the elastic moduli of the surrounding rock and support does not affect the arch range under a certain relative elastic modulus. Finally, field monitoring is conducted to validate the proposed method in actual support design.

关键词： pressure arch stress redistribution numerical simulation quantitative characterization longitudinal evolution parametric study

Sharper Hardy Uncertainty Relations on Signal Concentration in Terms of Linear Canonical Transform

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Chinese Journal of Electronics 2024年第5期33卷 1317-1325页

作者： Xiaogang xu Guanlei xu Xiaotong WANG College of Computer and Information Engineering Zhejiang Gongshang University

Linear canonical transform is of much significance to optics and information science. Hardy uncertainty principle, like Heisenberg uncertainty principle, plays an important role in various fields. In this paper, four new sharper Hardy uncertainty relations on linear canonical transform are derived. These new derived uncertainty relations are connected with the linear canonical transform parameters and indicate new insights for signal energy ***, for certain transform parameters, e.g. b = 0, these new proposed uncertainty relations break the traditional counterparts in signal energy concentration, as will result in new physical interpretation in terms of uncertainty principle. Theoretical analysis and numerical examples are given to show the efficiency of these new relations.

关键词： Information science Uncertainty Transforms Optics Hardy uncertainty principle Linear canonical transform Signal concentration PRINCIPLE

Data-Model Hybrid Driven Topology Identification Framework for Distribution Networks

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1478-1490页

作者： Dongliang xu Zaijun Wu Junjun xu Qinran Hu School of Electrical Engineering Southeast UniversityNanjing 210096China College of automation Nanjing University of Posts and TelecommunicationsNanjing 210096China

Extensive penetration of distribution energy resources(DERs)brings increasing uncertainties to distribution *** topology identification is a critical basis to guarantee robust distribution network *** algorithms that estimate distribution network topology have already been ***,most are based on data-driven alone method and are hard to deal with ever-changing distribution network physical *** these backgrounds,this paper proposes a data-model hybrid driven topology identification scheme for distribution ***,a data-driven method based on a deep belief network(DBN)and random forest(RF)algorithm is used to realize the distribution network topology rough ***,the rough identification results in the previous step are used to make a model of distribution network *** model transforms the topology identification problem into a mixed integer programming problem to correct the rough topology *** of the proposed method is verified in an IEEE 33-bus test system and modified 292-bus system.

关键词： Data-model hybrid driven DBN-RF mixed-integer programming topology identification

Identification of high oxygen-consuming substances in stormwater drainage systems illicitly connected with sewage system

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Journal of Environmental Sciences 2024年第4期138卷 132-140页

作者： Chen xu Zuxin xu Wenhai Chu Shanshan Wu Rong Xiao Lei Su State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and EngineeringTongji UniversityShanghai 200092China Ministry of Education Key Laboratory of Yangtze River Water Environment Tongji UniversityShanghai 200092China Guangzhou Resource Environmental Protection Technology Co. Ltd.Guangzhou 510030China

The dissolved oxygen content in water is an important indicator for assessing the quality of the water environment,and maintaining a certain amount of dissolved oxygen is essential for the healthy development of the ecological *** a water body is anoxic,the activity of anaerobic microorganisms increases and organic matter is decomposed to produce a large number of blackening and odorizing substances,resulting in black and odorous water bodies,which is a very common and typical phenomenon in ***,there is still a relatively universal occurrence of illicitly connected stormwater and sewage pipes in the urban drainage pipe network in China,which makes oxygen-consuming substances be directly discharged into rivers through stormwater pipes and consume the dissolved oxygen in the water bodies,resulting in an oxygen deficiency of the *** induces seasonal or year-round black and stink phenomena in urban ***,identifying high oxygen-consuming substances,which lays the foundation for the subsequent removal of oxygen-consuming substances,is *** a series of comparisons of water quality indicators and analysis of organic characteristics,it was found that the oxygen consumption capacity of domestic sewage was higher than that of industrial wastewater in the selected area of this study,and the oxygen-consuming substances of domestic sewage were small molecular amino *** comparing 20 conventional free amino acids,it was found that seven of them consumed oxygen easily,and compared with chemical oxygen consumption,biological oxygen consumption was in a leading position.

关键词： Urban drainage system Oxygen-consuming substances Domestic sewage Amino acid