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Big data in smart cities

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Science China(Information Sciences) 2015年第10期58卷 179-190页

作者： li DeRen cao JianJun YAO Yuan State Key Laboratory of Information Engineering in Surveying Mapping and Remote Sensing Wuhan University Collaborative Innovation Center of Geospatial Technology Geomatics Center of Gansu Province national Engineering Research Center for Multimedia Software Computer School Wuhan University

In this paper, we discuss the concept of the smart city, summarize its development, analyze the motivation and goals of building smart cities in China, and illustrate the supporting technologies of the smart city. Next, we propose a smart city infrastructure that is based on the concept of the digital city and integrates the Internet of Things and cloud computing technologies, thereby achieving automatic control and intelligence services for people and logistics in physical cities. We analyze the big data of smart cities according to ubiquitous sensor networks. Facing the problems and challenges caused by big data of smart cities, we propose a strategy to handle big data that focuses on cloud computing and data mining. In addition, we present a basic framework for cloud computing platforms and propose the establishment of an operating center for smart cities. In closing,we discuss the bright prospects of smart cities.

关键词： smart city big data digital city Internet of Things cloud computing data mining intelligence service

Comparative investigation on the heat transfer performance of an energy storage system with a spiral tube and straight tube:An experimental approach

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Science China(Technological Sciences) 2023年第1期66卷 71-85页

作者： MAO QianJun cao Yan li Tao School of Urban Construction Wuhan University of Science and TechnologyWuhan 430065China

Latent heat thermal energy storage systems can effectively fill the gap between energy storage and application, and phase-change materials(PCMs) are crucial media for storing thermal energy. Therefore, how to maximize the utilization efficiency of PCMs has attracted widespread attention. In this study, the thermal behavior of two thermal storage units employing a spiral tube and straight tube as heat transfer tubes was experimentally researched and comprehensively compared. Stefan numbers were used to investigate the impact of the heat transfer fluid temperature on the PCM melting process. The temperature distribution of PCMs,temporal evolution of the melting front, and temperature variations of measurement points in both tanks were compared. The average temperature and energy storage of PCMs were calculated to evaluate the thermal performance of different configurations. The results indicate that compared to cylinder B(with a straight tube), the energy storage in cylinder A(with a spiral tube)increased by 78.8%, 38.5%, and 19.6% at Stefan numbers of 1.08, 1.28, and 1.48, respectively. Moreover, the increase in the Stefan number simultaneously ascended the average temperature and energy storage of PCMs in containers A and B, causing the shortening of the melting time. When the Stefan number was increased from 1.28 to 1.48, the storage capacity was raised from3233.18 to 3463.8 k J, and the total melting time was decreased by 34.2% from 547.5 to 360 min after the PCM was loaded in cylinder A. The research results lay a certain foundation for a deeper study of enhanced heat transfer in spiral tubes.

关键词： thermal energy storage visualization experiment PCM spiral tube straight tube

New self-calibration schemes for accelerometers in platform INS

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Journal of Systems Engineering and Electronics 2015年第5期26卷 1032-1042页

作者： Hong Cai Anliang li Yuan cao College of Aerospace Science and Engineering National University of Defence Technology Science and Technology on Complex Land Systems Simulation Laboratory

To ensure success of precise navigation, it is necessary to carry out in-field calibration for the accelerometers in platform inertial navigation system(PINS) before a mission is *** continuous self-calibration methods are not fit for fast calibration of accelerometers because the platform misalignments have to be estimated precisely and the nonlinear coupling terms will affect accuracy. The multi-position methods with a "shape of motion" algorithm also have some existing disadvantages: High precision calibration results cannot be obtained when the accelerometer’s output data are used directly and it is difficult to optimize the calibration scheme. Focusing on this field, this paper proposes new fast self-calibration methods for the accelerometers of PINS. A data compression filter is employed to improve the accuracy of parameter estimation because it is impossible to obtain non-biased estimation for accelerometer parameters when using the "shape of motion" algorithm. Besides, continuous calibration schemes are designed and optimized by the genetic algorithm(GA) to improve the observability of parameters. Simulations prove that the proposed methods can estimate the accelerometer parameter more precisely than traditional continuous methods and multi-position methods, and they are more practical to deal with urgent situations than multi-position methods.

关键词： self-calibration accelerometers data compression genetic algorithm

Enhancing the hydration reactivity of hemi-hydrate phosphogypsum through a morphology-controlled preparation technology

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Chinese Journal of Chemical Engineering 2016年第9期24卷 1298-1305页

作者： lin Yang Jianxin cao Caiyu li School of Chemistry and Chemical Engineering Guizhou UniversityGuiyang 550025China College of Resource and Environmental Engineering Guizhou UniversityGuiyang 550025China Guizhou Key Laboratory.for Green Chemical and Clean Energy Technology Guiyang 550025China

The distribution of water channels in the crystal morphology of type-α hemi-hydrated gypsum(α-HH) was theoretically detected to investigate the effect of water channels on the hydration reactivity of hemi-hydrate phosphogypsum(HPG). Results showed that water channels were mainly distributed in the cylinders of α-HH crystal,whereas no water channel existed in the conical surfaces parallel to the z-axis. Increasing the number of water channels was critical to enhance the hydration activity of HPG compared with the hydration reactivity of industrial HPG and type-α high-strength gypsum. Controlling the technological parameters of crystallization by concentration of liquid-phase SO_4^(2-) made it possible to obtain HPG which had the stumpy crystals of α-HH and high hydration reactivity.

关键词： Hydration reactivity Morphology-controlled Water channel Hemi-hydrated phosphogypsum

Lyapunov Conditions for Finite-Time Input-to-State Stability of Impulsive Switched Systems

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IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 1057-1059页

作者： Taixiang Zhang Jinde cao Xiaodi li the School of Mathematics Southeast UniversityNanjing 210096China the School of Mathematics and Statistics Shandong Normal UniversityJinan 250014Chi

Dear Editor,This letter studies finite-time input-to-state stability(FTISS)for impulsive switched systems.A set of Lyapunov-based conditions are established for guaranteeing FTISS *** constituent modes governing continuous dynamics are FTISS and discrete dynamics involving impulses are destabilizing,the FTISS can be retained if impulsive-switching signals satisfy an average dwell-time(ADT)condition.

关键词： property impulsive satisfy

Ternary non-noble metal zinc-nickel-cobalt carbonate hydroxide cocatalysts toward highly efficient photoelectrochemical water splitting

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Journal of Materials Science & Technology 2018年第6期34卷 899-904页

作者： Fengren cao Wei Tian liang li College of Physics Optoelectronics and Energy Center for Energy Conversion Materials & Physics (CECMP) Jiangsu Key Laboratory of Thin Films Soochow University

TiO2 photoanodes have aroused intensive research interest in photoelectrochemical （PEC） water splitting. However, they still suffer from poor electron-hole separation and sluggish oxygen evolution dynamics, leading to the low photoconversion efficiency and limiting commercial application. Here, we designed and fabricated novel ternary non-noble metal carbonate hydroxide （ZNC-CH） nanosheet cocatalysts and integrated them with TiO2 nanorod arrays as highly efficient photoanodes of PEC cells. Compared with the pristine TiO2, the photocurrent of photoanode with the optimal amount of ZNC-CH represents 3.2 times enhancement, and the onset potential is shifted toward the negative potential direction of 62 mV, The remarkable enhancement is attributed to the suppressed carrier recombination and enhanced charge transfer efficiency at the interface of TiO2, ZNC-CH and electrolyte, which is closely related to the zinc elements modulated intrinsic activity of catalysts. Our results demonstrate that the introduction of multimetallic ZNC-CH cocatalysts onto photoanodes is a promising strategy to improve the PEC efficiency.

关键词： Photoelectrochemical cells TiO2 Cocatalysts Carbonate hydroxides Photoanodes

A Purely Elastic Instability and Mixing Enhancement in a 3D Curvilinear Channel Flow

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Chinese Physics Letters 2012年第9期29卷 105-109页

作者： li Feng-Chen ZHANG Hong-na cao Yang KUNUGI Tomoaki KINOSHITA Haruyuki OSHIMA Marie School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001 Department of Nuclear Engineering Kyoto UniversityKyoto 606-8501Japan Institute of Industrial Science The University of TokyoTokyo 153-8505Japan

We report the detailed information of a purely elastic instability and its mixing enhancement effect in a viscoelastic fluid flow driven by a constant pressure gradient along a curvilinear channel obtained for the first time from the three-dimensional direct numerical simulations(DNSs)of this kind of flow ***-dimensional unstable flow structures similar to those visualized in experiments are realized through the *** inception of elastic instability,conformation of microstructures,statistical and dynamic information of velocity field and the mixing enhancement effect caused by elastic instability are then discussed.

关键词： mixing flow Elastic

Elucidating the removal mechanism of N,N-dimethyldithiocarbamate in an anaerobic-anoxic-oxic activated sludge system

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Journal of Environmental Sciences 2014年第3期26卷 566-574页

作者： Yongmei li Xianzhong cao lin Wang State Key Laboratory of Pollution Control and Resource Reuse Tongji University Henan Institute of Metallurgy Henan Academy of Science

N,N-Dimethyldithiocarbamate （DMDTC） is a typical precursor of N-nitrosodimethylamine （NDMA）. Based on separate hydrolysis, sorption and biodegradation studies of DMDTC, a laboratory-scale anaerobic-anoxic-oxic （AAO） system was established to investigate the removal mechanism of DMDTC in this nutrient removal biological treatment system. DMDTC hydrolyzed easily in water solution under either acidic conditions or strong alkaline conditions, and dimethylamine （DMA） was the main hydrolysate. Under anaerobic, anoxic or oxic conditions, DMDTC was biodegraded and completely mineralized. Furthermore, DMA was the main intermediate in DMDTC biodegradation. In the AAO system, the optimal conditions for both nutrient and DMDTC removal were hydraulic retention time 8 hr, sludge retention time 20 day, mixed-liquor return ratio 3：1 and sludge return ratio 1：1. Under these conditions, the removal efficiency of DMDTC reached 99.5%; the removal efficiencies of chemical organic demand, ammonium nitrogen, total nitrogen and total phosphorus were 90%, 98%, 81% and 93%, respectively. Biodegradation is the dominant mechanism for DMDTC removal in the AAO system, which was elucidated as consisting of two steps： first, DMDTC is transformed to DMA in the anaerobic and anoxic units, and then DMA is mineralized to CO2 and NH3 in the anoxic and oxic units. The mineralization of DMDTC in the biological treatment system can effectively avoid the formation of NDMA during subsequent disinfection processes.

关键词： N N-dimethyldithioc arbamate hydrolysis biodegradation aerobic processes anaerobic processes wastewater treatment

Tracking control of redundant manipulator under active remote center-of-motion constraints: an RNN-based metaheuristic approach

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Science China(Information Sciences) 2021年第3期64卷 149-166页

作者： Ameer Hamza KHAN Shuai li Xinwei cao Department of Computing Hong Kong Polytechnic University Department of Electronics and Electrical Engineering Swansea University School of Management Shanghai University

In this paper, we propose a recurrent neural network(RNN) for the tracking control of surgical robots while satisfying remote center-of-motion(RCM) constraints. RCM constraints enforce rules suggesting that the surgical tip should not go beyond the region of incision while tracking the commands of the *** of RCM constraints can result in serious injury to the patient. We unify the RCM constraints with the tracing control by formulating a single constrained optimization problem using a penalty-term *** penalty-term actively rewards the optimizer for satisfying the RCM constraints. We then propose an RNN-based metaheuristic optimization algorithm called "Beetle Antennae Olfactory Recurrent Neural Network(BAORNN)" for solving the formulated optimization problem in real time. The proposed control framework can track the surgeon’s commands and satisfy the RCM constraints simultaneously. Theoretical analysis is performed to demonstrate the stability and convergence of the BAORNN algorithm. Simulations using LBR IIWA14, a 7-degree-of-freedom robotic arm, are performed to analyze the performance of the proposed framework.

关键词： tracking control surgical robots RCM constraints metaheuristic optimization recurrent neural network RNN redundant manipulator