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Chinese Journal of Chemistry 2021年第8期39卷 2163-2171页

作者： jing-Yi Wang Meng sun xian-Yang Yu Yu-Chen Zhang Wei Tan Feng Shi School of Chemistry and Materials Science Jiangsu Normal UniversityXuzhouJiangsu 221116China

Atroposelective construction of axially chiral alkene-heteroaryl scaffolds is highly desired but *** this work,we established an atroposelective construction of axially chiral alkene-indole scaffolds via the strategy ... 详细信息

关键词： Atropisomerism Axial chirality Asymmetric catalysis Indole Nucleophilic addition

Formation and reactivation mechanisms of large-scale ancient landslides in the Longwu River basin in the northeast Tibetan Plateau, China

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Journal of Mountain Science 2022年第6期19卷 1558-1575页

作者： TIAN jing-jing LI Tian-tao PEI xiang-jun DING Feng sun Hao XIE xian-gang GUO Jian State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China College of Earth Sciences Chengdu University of TechnologyChengdu 610059China School of Earth System Science Tianjin UniversityTianjin 300072China Department of Civil Engineering Panzhihua UniversityPanzhihua 617000China

The northeastern Tibetan Plateau exhibits steep topography and strong internal or external dynamic geological effect and is frequently subjected to strong earthquakes and heavy rainfall. The geological evolution has resulted in a wide distribution of ancient landslides, which has become a hotspot for studying ancient landslide formation and reactivation. In recent decades, several ancient landslides on both banks of the Longwu River, Qinghai Province, China were reactivated, causing serious economic losses and casualties. This study conducted remote sensing interpretation and ground surveys on these ancient landslides. Totally 59 ancient landslides were identified, and the formation mechanism, evolution process, and resurrection mechanism of the Longwu Xishan No.2 ancient landslide were analyzed by means of a detailed field geological survey, drilling, and series of experimental tests such as the particle size distribution test, the Xray diffraction test and the mechanical properties test. The results show that the formation of these ancient landslides is closely associated with the uplift of the Tibetan Plateau and the erosion of the Longwu River. Firstly, the intermittent uplift of the Tibetan Plateau lead to the diversion and downcutting of the Longwu River basin, which forms the alternate slope topography with steep and slow slopes, thereby providing favourable topography and slope structure conditions for the formation of landslides. Secondly, 34.5% clay-mineral content in the Neoproterozoic mudstone with 32.7% particle size less than 0.005 mm, and the corrosion and softening effects of the Neogene mudstone with high clay mineral content under the erosion of water provides favourable material conditions for the formation of landslides. Thirdly, rainfall and human activities are the primary triggering factors for the revival of this ancient landslide group. It is revealed that the evolution process of the ancient landslides on both banks of the Longwu River can

关键词： Remote sensing interpretation Tectonic movement Ancient landslide Reactivation mechanism Formation process Tibetan Plateau

Microstructure and Mechanical Properties of Mg–RE–TM Cast Alloys Containing Long Period Stacking Ordered Phases: A Review

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Acta Metallurgica Sinica(English Letters) 2019年第3期32卷 269-285页

作者： Huan Liu He Huang Jia-Peng sun Ce Wang jing Bai Ai-Bin Ma xian-Hua Chen College of Mechanics and Materials Hohai University College of Materials Science and Engineering Southeast University National Engineering Research Center for Magnesium Alloys (CCMg) Chongqing University

Casting magnesium alloys hold the greatest share of magnesium application products due to their short processing period, low cost and near net shape forming. Compared with conventional commercial magnesium alloys or other Mg–RE-based alloys, the novel Mg–RE–TM cast alloys with long period stacking ordered(LPSO) phases usually possess a higher strength and are promising candidates for aluminum alloy applications. Up to now, two ways: alloying design and casting process control(including subsequent heat treatments), have been predominantly employed to further improve the mechanical properties of these alloys. Alloying with other elements or ceramic particles could alter the solidifi cation pattern of alloys, change the morphology of LPSO phases and refi ne the microstructures. Diff erent casting techniques(conventional casting, rapidly solidifi cation, directional solidifi cation, etc.) introduce various microstructure characteristics, such as dendritic structure, nanocrystalline, metastable phase, anisotropy. Further heat treatments could activate the transformation of various LPSO structures and precipitation of diverse precipitates. All these evolutions exert great impacts on the mechanical properties of the LPSO-containing alloys. However, the underlying mechanisms still remain a subject of debate. Therefore, this review mainly provides the state of the art of the casting magnesium alloys research and the accompanying challenges and summarizes some topics that merit future investigation for developing high-performance Mg–RE–TM cast alloys.

关键词： Magnesium alloys Long period stacking ordered phase Casting Heat treatment Phase transformations Mechanical properties

A Study on Modeling and Optimization of Memory Systems

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Journal of Computer Science & Technology 2021年第1期36卷 71-89页

作者： Jason Liu Pedro Espina xian-He sun School of Computing and Information Sciences Florida International UniversityMiamiFL 33199U.S.A Department of Computer Science Illinois Institute of TechnologyChicagoIL 60616U.S.A

Accesses Per Cycle(APC),Concurrent Average Memory Access Time(C-AMAT),and Layered Performance Matching(LPM)are three memory performance models that consider both data locality and memory assess *** APC model measures the throughput of a memory architecture and therefore reflects the quality of service(QoS)of a memory *** C-AMAT model provides a recursive expression for the memory access delay and therefore can be used for identifying the potential bottlenecks in a memory *** LPM method transforms a global memory system optimization into localized optimizations at each memory layer by matching the data access demands of the applications with the underlying memory system *** three models have been proposed separately through prior *** paper reexamines the three models under one coherent mathematical *** specifically,we present a new memorycentric view of data *** divide the memory cycles at each memory layer into four distinct categories and use them to recursively define the memory access latency and concurrency along the memory *** new perspective offers new insights with a clear formulation of the memory performance considering both locality and ***,the performance model can be easily understood and applied in engineering *** such,the memory-centric approach helps establish a unified mathematical foundation for model-driven performance analysis and optimization of contemporary and future memory systems.

关键词： performance modeling performance optimization memory architecture memory hierarchy concurrent average memory access time

I/O Acceleration via Multi-Tiered Data Buffering and Prefetching

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Journal of Computer Science & Technology 2020年第1期35卷 92-120页

作者： Anthony Kougkas Hariharan Devarajan xian-He sun Department of Computer Science Illinois Institute of TechnologyChicago 60616U.S.A

Modern High-Performance Computing(HPC)systems are adding extra layers to the memory and storage hierarchy,named deep memory and storage hierarchy(DMSH),to increase I/O *** hardware technologies,such as NVMe and SSD,have been introduced in burst buffer installations to reduce the pressure for external storage and boost the burstiness of modern I/O *** DMSH has demonstrated its strength and potential in ***,each layer of DMSH is an independent heterogeneous system and data movement among more layers is significantly more complex even without considering *** to efficiently utilize the DMSH is a subject of research facing the HPC ***,accessing data with a high-throughput and low-latency is more imperative than *** prefetching is a well-known technique for hiding read latency by requesting data before it is needed to move it from a high-latency medium(e.g.,disk)to a low-latency one(e.g.,main memory).However,existing solutions do not consider the new deep memory and storage hierarchy and also suffer from under-utilization of prefetching resources and unnecessary ***,existing approaches implement a client-pull model where understanding the application's I/O behavior drives prefetching *** towards exascale,where machines run multiple applications concurrently by accessing files in a workflow,a more data-centric approach resolves challenges such as cache pollution and *** this paper,we present the design and implementation of Hermes:a new,heterogeneous-aware,multi-tiered,dynamic,and distributed I/O buffering *** enables,manages,supervises,and,in some sense,extends I/O buffering to fully integrate into the *** introduce three novel data placement policies to efficiently utilize all layers and we present three novel techniques to perform memory,metadata,and communication management in hierarchical buffering ***,we demonstrate the benefits

关键词： I/O buffering heterogeneous buffering layered buffering deep memory hierarchy burst buffers hierarchical data prefetching data-centric architecture

Position Measurement Based Slave Torque Feedback Control for Teleoperation Systems With Time-Varying Communication Delays

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IEEE/CAA Journal of Automatica Sinica 2023年第2期10卷 388-402页

作者： xian Yang jing Yan Changchun Hua Xinping Guan the Institute of Information Science and Engineering Yanshan University the Key Laboratory for Computer Virtual Technology and System Integration of Hebei Province Qinhuangdao 066004China IEEE the Institute of Electrical Engineering Yanshan UniversityQinhuangdao 066004China the Department of Automation Shanghai Jiao Tong UniversityShanghai 200240China

Bilateral teleoperation system is referred to as a promising technology to extend human actions and intelligence to manipulating objects *** the tracking control of teleoperation systems,velocity measurements are necessary to provide feedback ***,due to hardware technology and cost constraints,the velocity measurements are not always *** addition,the time-varying communication delay makes it challenging to achieve tracking *** paper provides a solution to the issue of real-time tracking for teleoperation systems,subjected to unavailable velocity signals and time-varying communication *** order to estimate the velocity information,immersion and invariance(I&I)technique is employed to develop an exponential stability velocity *** the proposed velocity observer,a linear relationship between position and observation state is constructed,through which the need of solving partial differential and certain integral equations can be ***,the mean value theorem is exploited to separate the observation error terms,and hence,all functions in our observer can be analytically *** the estimated velocity information,a slave-torque feedback control law is presented.A novel Lyapunov-Krasovskii functional is constructed to establish asymptotic tracking *** particular,the relationship between the controller design parameters and the allowable maximum delay values is ***,simulation and experimental results reveal that the proposed velocity observer and controller can guarantee that the observation errors and tracking error converge to zero.

关键词： Asymptotic stability bilateral teleoperation time-varying delay velocity observer

Visible and Near-Infrared Diffuse Reflectance Spectroscopy for Prediction of Soil Properties near a Copper Smelter

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Pedosphere 2012年第3期22卷 351-366页

作者： XIE xian-Li PAN xian-Zhang sun Bo Key Laboratory of Soil Environment and Pollution Remediation Institute of Soil ScienceChinese Academy of SciencesNanjing 210008(China) State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008(China)

Spatial and temporal monitoring of soil properties in smelting regions requires collection of a large number of sam- ples followed by laboratory cumbersome and time-consuming measurements. Visible and near-infrared diffuse reflectance spectroscopy （VNIR-DRS） provides a rapid and inexpensive tool to predict various soil properties simultaneously. This study evaluated the suitability of VNIR-DRS for predicting soil properties, including organic matter （OM）, pH, and heavy metals （Cu, Pb, Zn, Cd, and Fe）, using a total of 254 samples collected in soil profiles near a large copper smelter in China. Partial least square regression （PLSR） with cross-validation was used to relate soil property data to the reflectance spectral data by applying different preprocessing strategies. The performance of VNIR-DRS calibration models was evaluated using the coefficient of determination in cross-validation （R^2cv） and the ratio of standard deviation to the root mean standard error of cross-validation （SD/RMSEcv）. The models provided fairly accurate predictions for OM and Fe （R2v 〉 0.80, SD/RMSEcv 〉 2.00）, less accurate but acceptable for screening purposes for pH, Cu, Pb, and Cd （0.50 〈 Rcv 〈 0.80, 1.40 〈 SD/RMSEcv 〈 2.00）, and poor accuracy for Zn （R2v 〈 0.50, SD/RMSEcv 〈 1.40）. Because soil properties in conta- minated areas generally show large variation, a comparative large number of calibrating samples, which are variable enough and uniformly distributed, are necessary to create more accurate and robust VNIR-DRS calibration models. This study indicated that VNIR-DRS technique combined with continuously enriched soil spectral library could be a nondestructive alternative for soil environment monitoring.

关键词： heavy metal organic matter partial least squares regression soil environment monitoring spectral preprocessing

Event-based optimization with random packet dropping

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Science China(Information Sciences) 2020年第11期63卷 175-194页

作者： Qing-Shan JIA jing-xian TANG Zhenning LANG Center for Intelligent and Networked Systems Department of AutomationTsinghua University NetEase Inc.

Event-based optimization(EBO) provides a general framework for policy optimization in many discrete event dynamic systems where decision making is triggered by events that represent state transitions with common features. Because the number of events can be defined by the user and usually increases linearly with respect to the system scale, EBO has good potential to address large-scale problems where the state space grows exponentially. However, in many practical systems, sensors are geographically distributed and connected to a central controller through imperfect communication channels. Therefore, events observed by the sensors may not reach the controller. Optimization methods of event-based policies in these cases have not yet been identified. In this paper, we consider this important problem and make three major contributions. First, we formulate a mathematical EBO model in which the communication between sensors and controllers is subject to random packet dropping. Second, we show that this EBO model can be converted to another EBO model with perfect communication. Then, the performance difference equation and the performance derivative equation for event-based policies are straightforward to develop. One gradient-based policy iteration algorithm is developed for problems where the state transition probabilities are explicitly known, while another for problems where they are unknown. Third, the performance of the algorithms and the impact of the packet dropping probability on policy performance are numerically demonstrated on a single-zone occupant level estimation problem in buildings.

关键词： event-based optimization packet dropping discrete event dynamic systems

Surface embedded binary Co-Cu hydroxy phosphate over surface of oxy/hydroxides for efficient nitrate reduction to ammonia

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Nano Research 2025年第1期18卷 195-207页

作者： Chun Zhu Yifei Yang Yike jing Zhen Zeng Xuesong Yi Wei sun Fei Yang Key Laboratory of Agro-Forestry Environmental Processes and Ecological Regulation of Hainan Province School of Environmental Science and EngineeringHainan UniversityHaikou 570228China

Electrochemical nitrate reduction reaction(NO3RR)to ammonia is a promising approach to address excess Ncontamination in aqueous environment but suffers from a limited ammonia yield and selectivity due to the low concentration and sluggish *** work reports a three-dimensional porous electrode with binary Co_(2)Cu_(1)hydroxy phosphate embedded into the surface of Ni_(3)Co_(1)oxy/hydroxides(CoCu-PH@NiCo/Ni,“PH”means phosphate-hydroxide),which delivers a yield of 4.13 mg·h^(-1)·cm^(-2)with a high Faraday efficiency of 92.6%under a low nitrate concentration of 40 mM and provide an impressive *** embedded structure of the as-prepared catalyst exhibits unique metal coordination ligands and valence states different from the unitary *** electrochemical in situ infrared spectra and theoretical calculations revealed that the Co sites with the ability to dissociate water molecular to form adsorbed OH*can effectively provide the required protons for the deoxygenation and hydrogenation steps during NO3-conversion,thereby,effectively reducing the energy barrier of the key transition states in the NO3RR process to improve the intrinsic *** demonstrate that the rational design of binary components with the appropriate ability to activate water molecules as well as the threedimensional porous skeletal structure are expected to promote effectively the low-concentration nitrates conversion to ammonia.

关键词： nitrate reduction hydroxy phosphate surface embedded water dissociation active hydroxy adsorbed

Progress on Regulation of NLRP3 Inflammasome by Chinese Medicine in Treatment of Ulcerative Colitis

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Chinese Journal of Integrative Medicine 2023年第8期29卷 750-760页

作者： sun Hao-xian ZHU Ying Department of Gastroenterology the First Affiliated Hospital of Hunan University of Chinese MedicineChangsha(410007)China Hunan University of Chinese Medicine Changsha(410208)China

Ulcerative colitis(UC)is a chronic,non-specific intestinal disease that not only affects the quality of life of patients and their families but also increases the risk of colorectal *** nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing protein 3(NLRP3)inflammasome is an important component of inflammatory response system,and its activation induces an inflammatory cascade response that is involved in the development and progression of UC by releasing inflammatory cytokines,damaging intestinal epithelial cells,and disrupting the intestinal mucosal *** medicine(CM)plays a vital role in the prevention and treatment of UC and is able to regulate NLRP3 *** experimental studies on the regulation of NLRP3 inflammasome mediated by CM have been carried out,demonstrating that CM formulae with main effects of clearing heat,detoxifying toxicity,drying dampness,and activating blood *** and phenylpropanoids can effectively regulate NLRP3 *** active components of CM can interfere with the process of NLRP3 inflammasome assembly and activation,leading to a reduction in inflammation and UC ***,the reports are relatively scattered and lack systematic *** paper reviews the latest findings regarding the NLRP3 inflammasome activation-related pathways associated with UC and the potential of CM in treating UC through modulation of NLRP3 *** purpose of this review is to explore the possible pathological mechanisms of UC and suggest new directions for development of therapeutic tools.

关键词： NLRP3 inflammasome ulcerative colitis Chinese medicine mechanism of action review