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Multi-Step Clustering of Smart Meters Time Series:Application to Demand Flexibility Characterization of SME Customers

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Computer Modeling in Engineering & Sciences 2025年第1期142卷 869-907页

作者： Santiago bañales Raquel Dormido Natividad Duro Department of Computer Sciences and Automatic Control Universidad Nacional de Educación a Distancia(UNED)Madrid28040Spain Iberdrola Innovation Middle East Doha210177Qatar

Customer segmentation according to load-shape profiles using smart meter data is an increasingly important application to vital the planning and operation of energy systems and to enable citizens’participation in the energy *** study proposes an innovative multi-step clustering procedure to segment customers based on load-shape patterns at the daily and intra-daily time *** meter data is split between daily and hourly normalized time series to assess monthly,weekly,daily,and hourly seasonality patterns *** dimensionality reduction implicit in the splitting allows a direct approach to clustering raw daily energy time series *** intraday clustering procedure sequentially identifies representative hourly day-unit profiles for each customer and the entire *** the first time,a step function approach is applied to reduce time series *** attributes embedded in surveys are employed to build external clustering validation metrics using Cramer’s V correlation factors and to identify statistically significant determinants of load-shape in energy *** addition,a time series features engineering approach is used to extract 16 relevant demand flexibility indicators that characterize customers and corresponding clusters along four different axes:available Energy(E),Temporal patterns(T),Consistency(C),and Variability(V).The methodology is implemented on a real-world electricity consumption dataset of 325 Small and Medium-sized Enterprise(SME)customers,identifying 4 daily and 6 hourly easy-to-interpret,well-defined *** application of the methodology includes selecting key parameters via grid search and a thorough comparison of clustering distances and methods to ensure the robustness of the *** research can test the scalability of the methodology to larger datasets from various customer segments(households and large commercial)and locations with different weather and socioeconomic conditio

关键词： Electric load clustering load profiling smart meters machine learning data mining demand flexibility demand response

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Design Optimization of Non-Axisymmetric Vane for an Axial Compressor under Inlet Distortion

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Journal of Thermal Science 2023年第4期32卷 1321-1334页

作者： ZHANG Min DU juan ZHAO Hongliang QIU Jiahui ba Dun CHEN Yang NIE Chaoqun Digital Twin Research Center Institute of Engineering ThermophysicsChinese Academy of SciencesBeijing100190China Key Laboratory of Advanced Energy and Power Chinese Academy of SciencesBeijing100190China Innovation Academy for Light-Duty Gas Turbine Chinese Academy of SciencesBeijing100190China School of Engineering Science University of Chinese Academy of SciencesBeijing100049China

The flow field at the inlet of compressors is generally encountered combined total pressure and swirl distortion for either aircraft engine with S-duct or gas turbine with lateral air *** inevitably deteriorates compressor aerodynamic performance,including not only the efficiency or pressure ratio but also the operation *** order to conquer this issue,appropriate measures such as integrating flow control techniques and modifying inlet or compressor design are of *** to this motivation,this article develops a full-annular two-dimensional(2D)and a partial-annular three-dimension(3D)optimization strategy for non-axisymmetric vane ***,two numerical simulation methods for evaluating performance of full-annular 2D vane and compressor with partial-annular 3D vane are *** swirl patterns at the inlet of a 1.5-stage axial compressor are analyzed and parametrized,and the parameterization is transferred to characterize the circumferential distribution of geometrical parameters of the vane *** approaches dramatically reduce computational simulation costs without violating the non-axisymmetric flow distortion *** various full-annular 2D sections at different radial locations are constructed as design *** designed vane is reconstructed and 3D numerical simulations are performed to examine performance of the non-axisymmetric vane and the compressor with ***,partial annular 3D optimization is conducted for balancing compressor efficiency and stall *** indicate that the designed non-axisymmetric vane based on full-annular optimization approach can decrease the vane total pressure loss under the considered inlet flow distortion,while those using partial-annular optimization achieve positive effects on compressor stall margin.

关键词： combined total pressure and swirl distortion axial compressor non-axisymmetric vane optimization aerodynamic performance

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Cerium-based Sealing treatment of Mg–Al Hydrotalcite Film on AZ91D Magnesium Alloy

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Acta Metallurgica Sinica(English Letters) 2016年第11期29卷 993-1000页

作者： Qiang-Sheng Dong Zhi-Xin ba Zhang-Zhong Wang juan Kuang Zheng-Yang Cai Chen Yuan School of Materials Science and Engineering Nanjing　Institute of Technology Nanjing 211167 China Jiangsu Key Laboratory of Advanced Structural Materialsand Application Technology Nanjing 211167 China

An environment-friendly cerium-based sealing treatment was developed to improve the surface integrity and corrosion resistance of Mg–Al hydrotalcite film on AZ91D magnesium alloy. The cerium dioxide was generated through three stages namely nucleation, growth and dissolution, modifying the surface of AZ91D Mg alloy, and the hydrotalcite film became integral after being treated for 30 min. The results of polarization curves showed that the anti-corrosive performance of the hydrotalcite film was enhanced by the sealing treatment. Moreover, the immersion tests and electrochemical impedance spectrum measurements also demonstrated that the sealed hydrotalcite film provided a longer-term protection of magnesium alloy from corrosion as compared to the unsealed one.

关键词： AZ91D magnesium alloy Mg-Al hydrotalcite film Sealing treatment Ce-containing solution Corrosion resistance

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Optimal livelihood strategy for different poverty groups among farmers: a case study of the Qin-ba Mountain area in South-Shaanxi, China

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Journal of Mountain Science 2020年第5期17卷 1206-1220页

作者： SU Fang YIN Ya-juan School of Economics and Management Shaanxi University of Science&TechnologyXi'an 710021China

Achieving sustainable livelihood is the ultimate goal of poverty alleviation efforts in mountainous areas,and selecting an optimal livelihood strategy for different poverty-type farmers greatly improves farmers’livelihood capital,resists livelihood risks,and promotes sustainable *** farmers,optimal livelihood strategy means better employment opportunities,higher family income(or better income structure),and stronger employability or development *** paper classifies different types of farmers’poverty on the basis of a quantitative evaluation of farmers’livelihood capital in the Qin-ba Mountain Area in South-Shaanxi by using the k-means clustering method and subsequently the fuzzy evaluation method to evaluate the effectiveness of farmers’livelihood ***,the multi-attribute decision-making model is used to analyze the selection of optimal livelihood strategies for different poverty-type *** results suggest a significant difference in the selection of the optimal livelihood strategy for different poverty-type *** without financial and human capital choose to"go out to work,"farmers lacking natural capital choose to"acquire social insurance and government relief,"farmers without physical capital choose to"use loans,"and farmers lacking social capital choose to"use savings."Studying the selection of optimal livelihood strategies for different poverty-type farmers can help to propose targeted sustainable livelihood optimization programs for farmers and accelerate efforts to overcome poverty in mountainous areas.

关键词： Optimal strategy Livelihood capital Effectiveness evaluation Qin-ba Mountain Area Shaanxi

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Fabrication and analysis of TIG welding-brazing butt joints of in-situ TiB2/7050 composite and TA2

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Defence Technology（防务技术） 2021年第3期17卷 1062-1070页

作者： Huan-huan Sun Yi-bo Ren Yang Feng Hao-qiang ba Dong Chen Chun-juan Xia Hao-wei Wang School of Materials Science&Engineering Shenyang Ligong UniversityShenyangChina School of Materials Science&Engineering Shanghai Jiao Tong UniversityShanghaiChina

Lightweight hybrid structures of Al MMCs and titanium alloy dissimilar materials have great prospect in the defence industry application. So, it is necessary to join Al MMCs with Ti metal to achieve this structural design. In this work, in-situ Ti B_(2)/7050 composite and TA2 were firstly attempted to join by TIG welding-brazing technique. The result was that the intact welding-brazing butt joint was successfully fabricated. The joint presents dual characteristics, being a brazing on TA2 side and a welding on Ti B_(2)/7050 side. At brazing joint side, ER4043 filler metal effectively wets on TA2 under TIG heating condition,and a continuous interfacial reaction layer with 1 e3 mm is formed at welded metal/TA2 interface. The whole interfacial reaction layers are composed of Ti(Al Si)3 intermetallic compounds(IMCs), but their morphologies at the different regions present obvious distinguishes. The microhardness of the reaction layers is as much as 141 e190 HV. At welding joints side, the fusion zone appears the equixaed crystal structure, and the grain sizes are much smaller than those of welded metal, which is attributed to the effect of Ti B2 particulates from the melted Ti B_(2)/7050 on acceleration formation and inhibiting growth for the new crystal nucleus. The tensile test results show that average tensile strength of the optimal welding-brazing joint is able to achieve 138 MPa. The failure of the tensile joint occurs by quasi-cleavage pattern, and the cracks initiate from the IMCs layer at the groove surface of TA2 and propagate into the welded metal.

关键词： In-situ TiB2/7050 composite TA2 TIG welding-brazing Fabrication Analysis

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Estimating Risk-aware Flexibility Areas for Electric Vehicle Charging Pools via AC Stochastic Optimal Power Flow

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Journal of Modern Power Systems and Clean Energy 2023年第4期11卷 1247-1256页

作者： juan S.Giraldo Nataly bañol Arias Pedro P.Vergara Maria Vlasiou Gerwin Hoogsteen Johann L.Hurink Energy transition Studies Group Netherlands Organisation for Applied Scientific Research(TNO)Amsterdam1043 NTThe Netherlands Department of Electrical Engineering Mathematics and Computer ScienceUniversity of TwenteEnschede7522 NBThe Netherlands Intelligent Electrical Power Grids Group Electrical EngineeringMathematics and Computer ScienceDelft University of TechnologyDelft2628 CDThe Netherlands

This paper introduces an AC stochastic optimal power flow(SOPF)for the flexibility management of electric vehicle(EV)charging pools in distribution networks under *** AC SOPF considers discrete utility functions from charging pools as a compensation mechanism for eventual energy not served to their charging *** application of the AC SOPF is described where a distribution system operator(DSO)requires flexibility to each charging pool in a day-ahead time frame,minimizing the cost for flexibility while guaranteeing technical *** areas are defined for each charging pool and calculated as a function of a risk parameter involving the uncertainty of the *** show that all players can benefit from this approach,i.e.,the DSO obtains a riskaware solution,while charging pools/tasks perceive a reduction in the total energy payment due to flexibility services.

关键词： Electric vehicle flexibility management stochastic optimal power flow(SOPF) risk awareness compensation mechanism

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A group priority earliest deadline first scheduling algorithm

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Frontiers of Computer Science 2012年第5期6卷 560-567页

作者： Qi LI Wei ba School of Control Science and Engineering Dalian University of TechnologyDalian 116024China Science and Technology on Underwater Test and Control Laboratory Dalian 116013China

In most priority scheduling algorithms, the num- ber of priority levels is assumed to be unlimited. However, if a task set requires more priority levels than the system can support, several jobs must in practice be assigned the same priority level. To solve this problem, a novel group priority earliest deadline first （GPEDF） scheduling algorithm is pre- sented. In this algorithm, a schedulability test is given to form a job group, in which the jobs can arbitrarily change their or- der without reducing the schedulability. We consider jobs in the group having the same priority level and use shortest job first （SJF） to schedule the jobs in the group to improve the performance of the system. Compared with earliest deadline first （EDF）, best effort （BE）, and group-EDF （gEDF）, simu- lation results show that the new algorithm exhibits the least switching, the shortest average response time, and the fewest required priority levels. It also has a higher success ratio than both EDF and gEDF.

关键词： real-time system group priority success ratio,switching

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2.5D scattering of incident plane SV waves by a canyon in layered half-space

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Earthquake Engineering and Engineering Vibration 2010年第4期9卷 587-595页

作者： ba Zhenning Liang Jianwen Department of Civil Engineering Tianjin University Tianjin 300072 China Key Laboratory of Coast Civil Structure Safety （ Tianjin University） Ministry of Education

This paper presents a 2.5D scattering of incident plane SV waves by a canyon in a layered half-space by using the indirect boundary element method （IBEM）. A free field response analysis is performed to provide the displacements and stresses on the boundary of the canyon where fictitious uniform moving loads are applied to calculate the Green＇s *** for the displacements and stresses. The amplitudes of the loads are determined by the boundary conditions. The free field displacements are added to the fictitious uniform moving loads induced displacements and the total response is obtained. Numerical calculations are performed for a canyon with homogenous and in one layer over bedrock. The effects of the thickness and stiffness of the layer on the amplification are studied and discussed.

关键词： layered half-space canyon plane SV wave amplification scattering surface layer indirect boundaryelement method

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The effect of propagation delay on the dynamic evolution of the Bitcoin blockchain

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Digital Communications and Networks 2020年第2期6卷 157-166页

作者： Moustapha ba MODAL’X(Laboratoire de Modélisation aléatoire)of UniversitéParis Nanterre(Paris X) MODAL’X is the Mathematics and Computer Sciences laboratory of UniversitéParis Nanterre(Paris X)ministerial label EA 3454UFR SEGMIdépartement Mathématiques-Informatique200 avenue de la République92000NanterreFrance

This paper analyzes the selfish-mine strategy in the Bitcoin blockchain introduced in 2013 by *** and *** strategy could be used by a colluding pool of miners to earn more than their fair share of the mining revenue and in consequence to force other honest miners to join them to decrease the variance of their revenues and make their monthly revenues more *** is a very dangerous dynamic that could allow the rogue pool of miners to go toward a majority by accumulating powers of news adherents and control the entire *** that the propagation delay of information between any two miners in the network,which is not negligible and follows a normal distribution with mean proportional to the physical distance between the two miners,and a constant variance independent of others'delays,we prove that no guarantee can be given about the success or failure of the selfish-mine attack because of the variability of information propagation in the network.

关键词： Blockchain Bitcoin Mining Selfish-mine attack Propagation delay of information

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Salt effect on molecular orientation at air/liquid methanol interface

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Chinese Chemical Letters 2016年第4期27卷 535-539页

作者： Xia Li Gang-Hua Deng Rong-juan Feng Ke Lin Zhen Zhang Yu ba Zhou Lu Yuan Guo Beijing National Laboratory for Molecular Sciences State Key Laboratory of Molecular Reaction Dynamics Institute of Chemistry Chinese Academy of Sciences Hefei National Laboratory for Physical Sciences at the Microscale University of Science and Technology of China School of Physics and Optoelectronic Engineering Xidian University

The salt effects on molecular orientation at air/liquid methanol interface were investigated by the polarization-dependent sum frequency generation vibrational spectroscopy（SFG-VS）. We clarified that the average tilting angle of the methyl group to be u = 308 58 at the air/pure methanol surface assuming a d-function orientational distribution. Upon the addition of 3 mol/L Na I, the methyl group tilts further away from the surface normal with a new u = 418 38. This orientational change does not explain the enhancement of the SFG-VS intensities when adding Na I, implying the number density of the methanol molecules with a net polar ordering in the surface region also changed with the Na I concentrations. These spectroscopic findings shed new light on the salt effects on the surfaces structures of the polar organic solutions. It was also shown that the accurate determination of the bulk refractive indices and Raman depolarization ratios for different salt concentrations is crucial to quantitatively interpret the SFG-VS data.

关键词： Surface orientation Air/liquid interface Salt effect Sum frequency generation Methanol

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