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A GENERALIZATION OF GAUSS-KUZMIN-LE′VY THEOREM

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Acta Mathematica Scientia 2018年第3期38卷 965-972页

作者： peng sun China Economics and Management Academy Central University of Finance and Economic

We prove a generalized Gauss-Kuzmin-L′evy theorem for the generalized Gauss transformation Tp（x） = {p/x}.In addition, we give an estimate for the constant that appears in the theorem.

关键词： Gauss transformation transfer operator Gauss’ problem Hurwitz zeta function

ON THE ENTROPY OF FLOWS WITH REPARAMETRIZED GLUING ORBIT PROPERTY

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Acta Mathematica Scientia 2020年第3期40卷 855-862页

作者： peng sun China Economics and Management Academy Central University of Finance and EconomicsBeijing 100081China

We show that a flow or a semiflow with a weak form of reparametrized gluing orbit property has positive topological entropy if it is not minimal.

关键词： Flow gluing orbit property reparametrization minimality topological entropy

Preparation of steel slag porous sound-absorbing material using coal powder as pore former

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Journal of Environmental Sciences 2015年第10期27卷 67-75页

作者： peng sun Zhancheng Guo State Key Lab of Advanced Metallurgy University of Science and Technology

The aim of the study was to prepare a porous sound-absorbing material using steel slag and fly ash as the main raw material, with coal powder and sodium silicate used as a pore former and binder respectively. The influence of the experimental conditions such as the ratio of fly ash, sintering temperature, sintering time, and porosity regulation on the performance of the porous sound-absorbing material was investigated. The results showed that the specimens prepared by this method had high sound absorption performance and good mechanical properties, and the noise reduction coefficient and compressive strength could reach 0.50 and 6.5 MPa, respectively. The compressive strength increased when the dosage of fly ash and sintering temperature were raised. The noise reduction coefficient decreased with increasing ratio of fly ash and reducing pore former, and first increased and then decreased with the increase of sintering temperature and time. The optimum preparation conditions for the porous sound-absorbing material were a proportion of fly ash of 50%（wt.%）, percentage of coal powder of 30%（wt.%）, sintering temperature of 1130°C,and sintering time of 6.0 hr, which were determined by analyzing the properties of the sound-absorbing material.

关键词： Steel slag Porous sound-absorbing material Noise reduction coefficient Apparent porosity Compressive strength

Exponential decay of expansive constants

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Science China Mathematics 2013年第10期56卷 2063-2067页

作者： sun peng China Economics and Management Academy Central University of Finance and Economics

A map f on a compact metric space is expansive if and only if fn is *** study the exponential rate of decay of the expansive constant of fn and find some of its relations with other quantities about the dynamics,such ... 详细信息

关键词： expansive expansive constant generator exponential decay Lebesgue number box dimension topological entropy

Decontamination of Cr(VI) facilitated formation of persistent free radicals on rice husk derived biochar

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Frontiers of Environmental Science & Engineering 2019年第2期13卷 85-93页

作者： Kaikai Zhang peng sun Yanrong Zhang School of Environmental Science and Engineering Huazhong University of Science and TechnologyWuhan 430074China

This study investigated the facilitation of Cr(VI)decontamination to the formation of persistent free radicals(PFRs)on rice husk derived *** was found that Cr(VI)remediation by biochar facilitated the production of PFRs,which increased with the concentration of treated Cr(VI).However,excessive Cr(VI)would induce their *** with high pyrolysis temperature possessed great performance to Cr(VI)removal,which was mainly originated from its reduction by biochar from Inductively Coupled Plasma Optical Emission Spectroscopy and X-ray Photoelectron *** the corresponding generation of PFRs on biochar was primarily ascribed to the oxidization of phenolic hydroxyl groups by Cr(VI)from Fourier Transform Infrared Spectroscopy analysis,which was further verified by the H2O2 treatment *** findings of this study will help to illustrate the transformation of reactive functional groups on biochar and provide a new insight into the role of biochar in environmental remediation.

关键词： Biochar Persistent free radicals Phenolic hydroxyl groups Cr(VI) reduction

Numerical Simulation and Experimental Study of the Submarine's Cold Wake Temperature Character

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Journal of Thermal Science 2014年第3期23卷 253-258页

作者： CHEN Shengtao ZHONG Jingjun sun peng Marine Engineering College Dalian Maritime University

The temperature difference of the submarine's wake on the sea surface is the base for the IR detection. In this paper, the temperature difference on the sea surface caused by the submarine's propellers and the submarine's hull is studied by solving the three dimensional N-S equations. The results show that under the condition of sea temperature surroundings of minus gradient, such as in summer the upper water's temperature is higher than the lower water, it is cold wake on the sea surface and hot wake on the submarine's plane. The temperature difference between the wake and the water around in the wake's initial part becomes more and more obvious as the wake's distance gets longer. Through the IR camera, the submarine's propeller wake is studied under the same temperature status. Obvious IR temperature difference signals can be observed and it is consistent with the numerical simulation for the submarine.

关键词： submarine wake temperature difference IR

Accurate Measurement Method for Tube's Endpoints Based on Machine Vision

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Chinese Journal of Mechanical Engineering 2017年第1期30卷 152-163页

作者： LIU Shaoli JIN peng LIU Jianhua WANG Xiao sun peng School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

Tubes are used widely in aerospace vehicles, and their accurate assembly can directly affect the assembling reliability and the quality of products. It is important to measure the processed tube＇s endpoints and then fix any geometric errors correspondingly. However, the traditional tube inspection method is time-consuming and complex operations. Therefore, a new measurement method for a tube＇s endpoints based on machine vision is proposed. First, reflected light on tube＇s surface can be removed by using photometric linearization. Then, based on the optimization model for the tube＇s endpoint measurements and the principle of stereo matching, the global coordinates and the relative distance of the tube＇s endpoint are obtained. To confirm the feasibility, ll tubes are processed to remove the reflected light and then the endpoint＇s positions of tubes are measured. The experiment results show that the measurement repeatability accuracy is 0.167 mm, and the absolute accuracy is 0.328 ram. The measurement takes less than 1 min. The proposed method based on machine vision can measure the tube＇s endpoints without any surface treatment or any tools and can realize on line measurement.

关键词： machine vision non-contact measurement reflection light tube endpoint measurement

Hydrological Processes in the Huaihe River Basin, China： Seasonal Variations, Causes and Implications

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Chinese Geographical Science 2018年第4期28卷 636-653页

作者： sun peng sun Yuyan ZHANG Qiang YAO Rui College of Geography and Tourism Anhui Normal University Wuhu 241002 China Anhui Key Laboratory of Natural Disaster Process and Prevention Wuhu 241002 China Key Laboratory of Water Conservancy and Water Resources of Anhui Province Water Resources Research Institute of Anhui Province and Huaihe River China Bengbu 233000 China Key Laboratory of Environmental Change and Natural Disaster Ministry of Education Beijing Normal University Beijing 100875 China State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University Beijing 100875 China Academy of Disaster Reduction and Emergency Management Faculty of Geographical Science Beijing Normal University Beijing 100875 China

Understanding streamflow changes in terms of trends and periodicities and relevant causes is the first step into scientific management of water resources in a changing environment. In this study, monthly streamflow variations were analyzed using Modified Mann-Kendall(MM-K) trend test and Continuous Wavelet Transform(CWT) methods at 9 hydrological stations in the Huaihe River Basin. It was found that: 1) streamflow mainly occurs during May to September, accounting for 70.4% of the annual total streamflowamount with Cv values between 0.16–0.85 and extremum ratio values between 1.70–23.90; 2) decreased streamflow can be observed in the Huaihe River Basin and significant decreased streamflow can be detected during April and May, which should be the results of precipitation change and increased irrigation demand; 3) significant periods of 2–4 yr were detected during the 1960 s, the 1980 s and the 2000 s. Different periods were found at stations concentrated within certain regions implying periods of streamflow were caused by different influencing factors for specific regions; 4) Pacific Decadal Oscillation(PDO) has the most significant impacts on monthly streamflow mainly during June. Besides, Southern Oscillation Index(SOI), North Atlantic Oscillation(NAO) and the Ni?o3.4 Sea Surface Temperature(Ni?o3.4) have impacts on monthly streamflow with three months lags, and was less significant in time lag of six months. Identification of critical climatic factors having impacts on streamflow changes can help to predict monthly streamflow changes using climatic factors as explanatory variables. These findings were well corroborated by results concerning impacts of El Nino-Southern Oscillation(ENSO) regimes on precipitation events across the Huaihe River Basin. The results of this study can provide theoretical background for basin-scale management of water resources and agricultural irrigation.

关键词： streamflow trend periodicity abrupt behavior climate indices Huaihe River Basin China

Stability Control Method for Hybrid AC-DC Transmission Systems Considering Cross-region Multi-energy Coordination

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CSEE Journal of Power and Energy Systems 2021年第4期7卷 753-760页

作者： peng sun Yun Teng Ouyang Leng Zhe Chen Shenyang University of Technology Shenyang 110870China State Grid East Inner Mongolia Economic Research Institute Huhhot 010020China Department of Energy Technology Aalborg UniversityAalborgDenmark

China has built the largest hybrid AC-DC power systems with the highest voltage levels in the *** to effectively guarantee the stable operation of the hybrid AC-DC power systems is a critical undertaking and technical *** view of the stability problems of hybrid AC-DC transmission systems with a high percentage of wind power,a hybrid AC・DC transmission system's stability control method that considers cross-region multi-energy coordination is established in this *** at the uncertainty of a high percentage of wind power,the dynamic inversion method is used as the inner loop for robust control,and the battery energy storage and regenerative electric boiler are used as multiple energy sources to coordinate,and the outer loop robust control is used for uncertainty *** hybrid AC-DC weak-sending terminal system with wind power is analyzed and designed by//-synthesis based on the Hg control,and a stability control method for hybrid AC-DC transmission systems,considering cross-region multi-energy coordination,is *** results show that the model proposed in this paper can guarantee the robustness of the dynamic inversion method and improves the control performance of AC-DC transmission systems.

关键词： AC-DC transmission system multi-energy coordination robust control uncertainty