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Impact of anthropogenic activities on vegetation dynamics in a reservoir area: model establishment and a case study of Longkaikou Reservoir in China

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Journal of Mountain Science 2021年第7期18卷 1823-1836页

作者： YANG Wei PEI jun CAI Yan-peng YI Yu-jun State Key Laboratory of Water Environment Simulation School of EnvironmentBeijing Normal UniversityBeijing 100875China Binjiang Branch Agency of Ecology and Environment of HangzhouHangzhou 310053China

Vegetation in hot and arid valleys is a crucial indicator of ecosystem health,but is vulnerable to human activities and environmental *** the Longkaikou Reservoir in the Jinsha River in southwestern China as a case study,we developed a spatially explicit model that combined the plant growth,fruiting,seed dispersal,and seed germination stages to reveal the potential impact of multiple human activities(reservoir construction,logging,grazing,and aerial seeding) on the vegetation dynamics of Dodonaea viscosa and Pinus *** reservoir construction,the grassland area of 68 km^(2) in 2003 decreased to 24 km^(2) in 2018,replaced by forest,shrubland,and bodies of water,and the precipitation increased during the dry season,which indicated the improvement of the local plant and soil *** model predicted that when soil moisture decreased by more than 20% compared to current levels,the area of *** increased greatly at low elevations;however,when at higher soil moisture,*** would occupy more of the study *** and grazing would slightly change the spatial pattern of vegetation and delay *** communities from achieving stability by directly reducing plant *** such as aerial seeding would increase the total area by 13.13 km^(2) and 8.09 km^(2) of two plants,respectively,and accelerate the stabilization of plant *** effects of multiple human activities on vegetation may counteract each other;for example,logging decreased the *** area whereas aerial seeding increased it,and plant biomass changed in response to this *** the complex relationships between vegetation and human impacts,our study provides a scientific basis for vegetation restoration and ecological security in this hot and arid valley.

关键词： Spatially explicit model Vegetation dynamics Human activities Longkaikou Reservoir

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Numerical simulation of rock-breaking and influence laws of dynamic load parameters during axial-torsional coupled impact drilling with a single PDC cutter

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Petroleum Science 2023年第3期20卷 1806-1827页

作者： Yan Xi Hao-Yu Wang Chun-Qing zha jun Li Gong-Hui Liu Bo-Yun Guo Beijing University of Technology Bejing100124China China University of Petroleum-Bejing Beijing102249China China University of Petroleum-Beijing at Karamay KaramayXinjiang834000China University of Louisiana at Lafayett Lafayette70504USA

Axial and torsional impact drilling technology is used to improve the drilling efficiency of hard rock formation in the deep ***,the corresponding theory is not mature,and there are few correlative research reports on the rock-breaking mechanism of axial and torsional coupled impact drilling *** the influence of the impact hammer geometry and movement on the dynamic load parameters(i.e.,wavelength,amplitude,frequency,and phase difference),a numerical model that includes a hard formation and single polycrystalline diamond compact cutter was *** Riedel-Hiermaier-Thoma model,which considers the dynamic damage and strength behavior of rocks,was adopted to analyze the rock damage under axial and torsional impact *** numerical simu-lation results were verified by the experimental *** was found that compared with conventional drilling,the penetration depths of axial,torsional,and axial-torsional coupled impact drilling increased by 31.3%,5.6%,and 34.7%,*** the wavelength and amplitude of the axial impact stress wave improved the penetration *** the bit rotation speed remained unchanged,increasing the frequency in the axial and circumferential directions had little effect on the penetration ***,as the frequency increased,the cutting surface became increasingly smooth,which reduced the occurrence of bit *** the phase difference between the axial and circumfer-ential stress waves was 25%,the penetration depth significantly *** addition,the bit vibration problem can be effectively ***,the adjustment of engineering and tool structure parameters is proposed to optimize the efficiency of the axial-torsional coupled impact drilling tool.

关键词： Axial-torsional coupled impact drilling tool Rock-breaking PDC cutter RHT model

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Intramolecular Hydrogen Bond Improved Durability and Kinetics for Zinc‑Organic Batteries

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Nano-Micro Letters 2024年第3期16卷 138-148页

作者： Tianjiang Sun jun Pan Weijia zhang Xiaodi Jiang Min Cheng Zhengtai zha Hong Jin Fan zhanliang Tao Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Renewable Energy Conversion and Storage CenterCollege of ChemistryNankai UniversityHaihe Laboratory of Sustainable Chemical TransformationsTianjin 300071People’s Republic of China School of Physical and Mathematical Sciences Nanyang Technological UniversitySingapore 637371Singapore Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and EngineeringTongji UniversityShanghai 200092People’s Republic of China

Organic compounds have the advantages of green sustainability and high designability,but their high solubility leads to poor durability of zinc-organic ***,a high-performance quinone-based polymer(H-PNADBQ)material is designed by introducing an intramolecular hydrogen bonding(HB)*** intramolecular HB(C=O⋯N-H)is formed in the reaction of 1,4-benzoquinone and 1,5-naphthalene diamine,which efficiently reduces the H-PNADBQ solubility and enhances its charge transfer in *** situ ultraviolet-visible analysis further reveals the insolubility of H-PNADBQ during the electrochemical cycles,enabling high durability at different current ***,the H-PNADBQ electrode with high loading(10 mg cm^(-2))performs a long cycling life at 125 mA g^(-1)(>290 cycles).The H-PNADBQ also shows high rate capability(137.1 mAh g^(−1)at 25 A g^(−1))due to significantly improved kinetics inducted by intramolecular *** work provides an efficient approach toward insoluble organic electrode materials.

关键词： Zn-organic batteries H-PNADBQ polymer Intramolecular hydrogen bond Reduced solubility Improvedπ-conjugated level

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Preparation and Electrochemical Performance of Nano-Co_3O_4 Anode Materials from Spent Li-Ion Batteries for Lithium-Ion Batteries

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Journal of Materials Science & Technology 2013年第3期29卷 215-220页

作者： Chuanyue Hu jun Guo Jin Wen Yangxi peng Department of Chemistry and Materials Science Hunan Institute of HumanitiesScience and Technology

A hydrometallurgical process for the recovery of cobalt oxalate from spent lithium-ion batteries was used to recycle cobalt compound by using alkali leaching, reductive acid leaching and chemical deposition of cobalt oxalate. The recycled cobalt oxalate was used to synthesize nano-Co3O4 anode material by sol-gel method. The samples were characterized by thermal gravity analysis and differential thermal analysis （TGA/DTA）, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and charge/discharge measurements. The influence of molar ratio of Co2＋ to citric acid and calcination temperature on the structure and electrochemical performance of nano-Co3O4 was evaluated. As the molar ratio of Co2＋ to citric acid is 1：1, the face-centered cubic （fcc） Co3O4 powder shows the discharge capacity of 760.9 mA h g-1, the high coulombic efficiency of 99.7% in the first cycle at the current density of 125 mA g-l, and the excellent cycling performance with the reversible capacity of 442.3 mA h g-1 after 20 cycles at the current density of 250 mA g-1.

关键词： Spent lithium-ion batteries Sol-gel method Reductive acid leaching Nanostructure cobalt oxide Electrochemical behavior

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Development and application of a water pollution emergency response system for the Three Gorges Reservoir in the Yangtze River, China

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Journal of Environmental Sciences 2011年第4期23卷 595-600页

作者： Qiang He Shujuan peng jun zhai Haiwen Xiao Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of Education Chongqing University Chongqing 400045 China.

There are many watercraft and production accidents in the Three Gorges Reservoir Area （TGRA） of the Yangtze River in China every year. Accidents threaten the water quality of the 1085 km 2 surface area of the TGRA and millions of local people if oil and chemical leakage were to occur. A water pollution management system for emergency response （WPMS ER） was therefore designed for the management of pollution in this area. An integrated geographic information system （GIS）-based water pollution management information system for the TGRA, called WPMS ER TGRA, was developed in this study. ArcGIS engine was used as the system development platform, and Visual Basic as the programming language. The models for hydraulic and water quality simulation and the generation of body-fitted coordinates were developed and programmed as a dynamically linked library file using Visual Basic, and they can be launched by other computer programs. Subsequently, the GIS-based information system was applied to the emergency water pollution management of a shipwreck releasing 10 tons of phenol into the Yangtze River during two hours. The results showed that WPMS ER TGRA can assist with emergency water pollution management and simulate the transfer and diffusion of accidental pollutants in the river. Furthermore, it can quickly identify the affected area and how it will change over time within a few minutes of an accident occurring.

关键词： water pollution emergency emergency response management information system the Three Gorges Reservoir

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Variable strength combinatorial testing of concurrent programs

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Frontiers of Computer Science 2016年第4期10卷 631-643页

作者： Xiaofang QI jun HE peng WANG Huayang ZHOU School of Computer Science and Engineering Southeast University Nanjing 211189 China Key Laboratory of Computer Network and Information Integration Ministry of Education Southeast University Nanjing 211189 China NARI Relays Electric Cooperation Nanjing 211102 China

Reachability testing is an important approach to testing concurrent programs. It generates and exercises syn- chronization sequences automatically and on-the-fly without saving any test history. Existing reach, ability testing can be classified into exhaustive and t-way testing. Exhaustive testing is impractical in many cases whilie t-way testing may decrease the capability of fault detection in some cases. In this paper, we present a variable strengda reachability testing strategy, which adopts the dynamic framework of reachability testing and uses a variable strength combinatorial strategy. Different parameter groups are provided with different covering strength. Variable strength testing covers no t-way combinations but the necessary combinations of parameters having mutual interactions in a concurrent program. It is more reasonable than t-way testing because uniform interactions between parameters do not often exist in concurrent systems. We propose a merging algorithm that implements the variable strength combinatorial testing strategy and conduct our experiment on several concurrent programs. The experimental results indicate that our variable strength reachability testing reaches a good tradeoff between the effectiveness and efficiency. It can keep the same capability of fault detection as exhaustive reachability testing while substantially reducing the number of synchronization sequences and decreasing the execution time in most cases.

关键词： software testing variable strength combinatorial testing concurrency testing reachability testing

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Selective electrocatalytic CO2 reduction enabled by SnO2 nanoclusters

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Journal of Energy Chemistry 2019年第10期28卷 93-96页

作者： Hui Yang Yang Huang jun Deng Yunling Wu Na Han Chenyang zha Leigang Li Yanguang Li Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices Institute of Functional Nano & Soft Materials (FUNSOM) Soochow University

The development of high-performance electrocatalysts holds the decisive key to the electrochemical CO2 reduction toward value-added products. Formic acid or formate is a desirable reduction product, but its selective production is often challenging. Tin based-materials have attracted great attention for formate production, and yet their performances are far from satisfactory. In this study, we reported the preparation of SnO2 nanoclusters from the controlled self-polymerization of dopamine together with SnO32-, followed by the mild-temperature calcination. The final product consisted of large primary particles that were further made of small secondary SnO2 nanocrystals. When evaluated as the electrocatalyst for CO2 reduction in 0.5 M NaHCO3, our material exhibited impressive activity, selectivity and stability for the selective CO2 reduction to formate. A peak formate Faradaic efficiency of^73% and large partial current density of 16.3 mA/cm2 was achieved at -0.92 V versus reversible hydrogen electrode.

关键词： CO2 reduction reaction Electrocatalysts Formate Tin oxide Selectivity

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Design of adiabatic two's complement multiplier-accumulator based on CTGAL

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第2期10卷 172-178页

作者： peng-jun WANG Jian XU Shi-yan YING Institute of Circuits and Systems Ningbo University Ningbo 315211 China College of Information Engineering Zhej iang University of Technology Hangzhou 310014 China

We propose a new design scheme for a Booth encoder based on clocked transmission gate adiabatic logic(CTGAL). In the new design the structural complexity of the Booth encoder is reduced while the speed of the multiplier is improved. The adiabatic two's complement multiplier-accumulator(MAC) is furthermore a design based on the CTGAL. The computer simulation results indicate that the designed circuit has the correct logic function and remarkably less energy consumption compared to that of the MAC based on complementary metal oxide semiconductor(CMOS) logic.

关键词： CTGAL circuit Adiabatic circuit Booth arithmetic Multiplier Two's complement MAC

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Effects of TMCP Schedule on Precipitation,Microstructure and Properties of Ti-microalloyed High Strength Steel

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Journal of Iron and Steel Research International 2016年第6期23卷 593-601页

作者： Xiang-dong HUO Lie-jun LI Zheng-wu peng Song-jun CHEN School of Material Science and Engineering Jiangsu University School of Mechanical and Automotive Engineering South China University of Technology

Using the similar compositions of the Ti-microalloyed high-strength steels produced by the thin-slab casting process of compact strip production（CSP）,four thermo-mechanical control processes（TMCP）after the simulated thickslab casting,*** two hot rolling routes and the two cooling processes,were designed,aiming at achieving the same mechanical properties as the thin strip *** final microstructures after the four TMCP processes were examined by optical microscope（OM）,scanning electron microscope（SEM）and transmission electron microscope（TEM）.The tensile properties and Charpy impact energy were measured ***-induced TiC precipitation was found in the two-stage rolling route with the finish rolling temperature at low levels,leading to grain refinement due to the pinning effect during austenite *** hardening in ferrite was observed when a period of isothermal holding was applied after hot *** could be concluded that both finish rolling temperature and the subsequent isothermal holding temperature were crucial for the achieved strength level due to the combined effect of grain refinement and precipitation *** the same time,it was found that the isothermal holding led to poor impact toughness because of remarkable precipitation ***,it was suggested that the precipitation kinetics of titanium carbides in both austenite and ferrite should be investigated in future.

关键词： TMCP refinement hardening holding rolling titanium isothermal Precipitation austenite ferrite

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Adaptive Multi-Bernoulli Filter Without Need of Prior Birth Multi-Bernoulli Random Finite Set

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Chinese Journal of Electronics 2018年第1期27卷 115-122页

作者： YUAN Changshun WANG jun LEI peng SUN Jinping School of Electronic and Information Engineering Beihang University

Conventional Multi-Bernoulli(MBer) filter assumes that the birth MBer Random finite set(RFS)is known a priori. However, this is not true for practical scenario. This paper proposes a novel extension of the MBer filter which eliminates the reliance of the prior birth MBer RFS and relaxes the limitation in new-born target appearance volume. The proposed filter classifies the measurements into survival measurements and birth measurements, and adaptively generates the birth MBer RFS using the birth measurements. The novel filtering equations that distinguish the persistent and new-born targets are derived. A Sequential Monte-Carlo(SMC) implementation of the proposed filter is given. Simulations are performed to verify the improvement in the performance of the proposed filter.

关键词： Random finite set Adaptive multi-Bernoulli filter Sequential Monte-Carlo Multi-target tracking

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