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Power Flow Analytical Solutions and Multi-dimensional Voltage Stability Boundaries Based on Multivariate Quotient-difference Method

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1168-1178页

作者： Chengxi liu Qiupin lai School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China Hubei Engineering and Technology Research Center for AC/DC Intelligent Distribution Network Wuhan 430072China IEEE

This paper proposes a novel Multivariate Quotient-Difference(MQD)method to obtain the approximate analytical solution for AC power flow ***,in the online environment,the power flow solutions covering different operating conditions can be directly obtained by plugging values into multiple symbolic variables,such that the power injections and consumptions of selected buses or areas can be independently *** method first derives a power flow solution through a Multivariate Power Series(MPS).Next,the MQD method is applied to transform the obtained MPS to a Multivariate Pad´e Approximants(MPA)to expand the Radius of Convergence(ROC),so that the accuracy of the derived analytical solution can be significantly *** addition,the hypersurface of the voltage stability boundary can be identified by an analytical formula obtained from the coefficients of *** direct method for power flow solutions and voltage stability boundaries is fast for many online applications,since such analytical solutions can be derived offline and evaluated online by only plugging values into the symbolic variables according to the actual operating *** proposed method is validated in detail on New England 39-bus and IEEE 118-bus systems with independent load variations in multi-regions.

关键词： Analytical power flow solution multivariate power series multivariate Padéapproximants multivariate quotient-difference multi-dimensional voltage stability boundary

Remote sensing image encryption algorithm utilizing 2D Logistic memristive hyperchaotic map and SHA-512

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Science China(Technological Sciences) 2024年第5期67卷 1553-1566页

作者： lai Qiang liu Yuan YANG Liang School of Electrical and Automation Engineering East China Jiaotong UniversityNanchang330013China

The two-dimensional Logistic memristive hyperchaotic map(2D-LMHM)and the secure hash SHA-512 are the foundations of the unique remote sensing image encryption algorithm(RS-IEA)suggested in this *** proposed map is formed from the improved Logistic map and the memristor,which has wide phase space and hyperchaotic range and is exceptionally excellent to be utilized in specific *** proposed image algorithm uses the permutation-assignment-diffusion *** generates two position matrices in a progressive manner to achieve an efficient random exchange of pixel positions,assignment is carried through on the image pixels of the permutated image to entirely remove the original image information,strengthening the relationship between permutation and diffusion,and loop diffusion in two different directions can use subtle changes of pixels to affect the whole *** random key and plain-image SHA-512 hash values are used to produce an additional key,which is then utilized to figure out the permutation parameters and the initial value of a chaotic *** experimental results with the average NPCR=99.6094%(NPCR:number of pixels change rate),average UACI=33.4638%(UACI:unified average changing intensity),100%pass rate of the targets in the test set,the average correlation coefficient is 0.00075,and the local information entropy is 7.9025,which shows that the algorithm is able to defend against a variety of illegal attacks and provide more trustworthy protection than some of the existing state-of-the-art algorithms.

关键词： chaos memristive hyperchaotic map remote sensing SHA-512 image encryption RS-IEA

Numerical study on the blocking effect of skin on Flash-Ball Impact and damage assessment

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Defence Technology（防务技术） 2024年第3期33卷 532-545页

作者： Dihua Ouyang Chunwei qin Xiaowen qin Qiantao Zhang Xingyu liu Xi'an University of Architecture and Technology Xi'an 710055China Analysis and Testing Center Xi'an University of Architecture and TechnologyXi'an 710055China Engineering University of PAP Xi'an 710086China

To explore the response law of non-lethal large-size kinetic energy projectiles to blunt attack on skin tissue,and to evaluate the skin injury characteristics of the attacked personnel and the use safety of kinetic energy *** on the LS-DYNA simulation software,a three-layer skin simulation model and a Flash-Ball rubber bullet model are established,and the force-time and deformation-time biomechanical corridors of the Flash-Ball rubber bullet impacting human skin tissue are *** corridor curve and the energy transfer and diffusion are analyzed and *** safety evaluation of the damage caused by the rubber bullet shooting a human body at different distances is carried out using the empirical formula of the penetration ***,the safe shooting distance is *** results show that the model used in the simulation has a good correlation with the experimental data,its biomechanical corridor characteristics are different from those of conventional vehicle impact and smallsize projectile response *** energy transfer and action time of medium and low-speed impact may cause greater *** fat layer is the largest energy absorption *** minimum safe shooting distance to ensure skin tissue from penetrating damage is 15.8 m,and the limit specific kinetic energy of skin damage is 7.88 J/cm^(2).This study can be extended to the study of biomechanical response law and safety evaluation under the impact of the same type of large kinetic energy projectile,which provides an important theoretical reference for the police to use large kinetic energy projectiles to conduct safe shooting in peacekeeping operations.

关键词： KIPs Blunt strike Biomechanical response Damage analysis

Comprehensive DNA barcode reference library and optimization of genetic divergence threshold facilitate the exploration of species diversity of green lacewings (Neuroptera: Chrysopidae)

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Insect Science 2024年第2期31卷 613-632页

作者： Yan lai Kaiyu Li Xingyue liu Deparment of Entomology Cllege of Plant ProtectionChina Agricultural UniversityBejingChina College of Bioogical Sciencs China Agricultural UniversityBeijingChina

Chrysopidae are a family of Neuroptera of significant importance in biocontrol against agricultural pests because of their predatory ***,the taxonomy of Chrysopidae lacks a comprehensive revision,which impedes the exploration of species diversity as well as the selection and the conservation of green lacewings as biocontrol *** have established a DNA barcode reference library of the Chinese green lacewings based on an approximately complete sampling(95.63%)in 25 of the 34 provincial regions in China,comprising 1119 barcodes of 25 genera and 197 species(representing 85%genera and 43.62%species from China).Combining other 1049 high quality green lacewing DNA barcodes,we first inferred the optimal threshold of interspecific genetic divergence(1.87%)for successful species identification in multiple simulated scenarios based on present *** further inferred the threshold of genetic divergence(7.77%)among genera with biocontrol *** inference and performance of the threshold appears to be mainly associated with the completeness of sampling,the proportion of closely related species,and the analytical *** new combinations,Apertochrysa platypa(Yang&Yang,1991)***.,Apertochrysa shennongana(Yang&Wang,1990)***.,Apertochrysa pictifacialis(Yang,1988)***.,Apertochrysa helana(Yang,1993)***.,Plesiochrysa rosulata(Yang&Yang,2002)***.,and Signochrysa hainana(Yang&Yang,1991),are proposed according to integrative species *** library and optimal threshold will effectively facilitate the exploration of species diversity of green *** study also provides a methodological reference in molecular delimitation of other insects.

关键词： Chrysopidae DNA barcode genetic distance optimal threshold species delimitation

Design and performance investigation of modified dual reflector parabolic trough collector with double planar mirrors

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Science China(Technological Sciences) 2024年第3期67卷 902-918页

作者： LI Peijing liu TaiXiu qin YuanLong LI JiChao liu QiBin School of Energy Powerand Mechanical EngineeringNorth China Electric Power University Beijing 226China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei 230027China

In a typical parabolic trough collector(PTC), sunlight is concentrated at the bottom of the absorber tube. This concentrated solar flux leads to uneven heat distribution, resulting in high local temperatures and significant thermal stress on the absorber *** limitations have restricted the application of PTCs in solar thermochemistry and other fields and have impacted their safe operation. In this study, a new PTC with dual planar mirrors(DPMS) is proposed to homogenize the circumferential solar flux distribution of the absorber tube. A design method and single-objective optimization of the new PTC with a DPMS are proposed,and an uncertainty analysis of the operational and structural parameters is performed. A coupled light-heat-structure numerical model was developed to study the heat transfer performance and structural mechanical properties. The thermodynamic properties of the PTC with DPMS under different boundary conditions were analyzed. The results show that the circumferential temperature difference of the new PTC is within 2.6 K, and the circumferential thermal deformation is within 0.9 mm under typical working conditions(the inlet velocity of the heat transfer fluid is 3 m/s, inlet temperature is 573.15 K, and the direct normal irradiance is 1000 W/m^(2)). Compared with conventional PTCs, the circumferential temperature difference is reduced by 74%–90%, and the maximum thermal deformation along the y-axis is reduced by more than 95% under all working conditions(1–5 m/s, 373.5–675.15 K, 200–1000 W/m^(2)). The new PTC maintains the uniformity of the circumferential solar flux distribution for different operating parameters(sun incident angle of 0°–3°) and installation errors(±3 mm), is suitable for solar energy applications in various fields, and has the potential for large-scale applications.

关键词： solar thermal energy parabolic trough collector secondary reflector solar flux distribution optical optimization

Capturability-based Fuzzy Footstep Planner for a Biped Robot with Centroidal Compliance

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Journal of Bionic Engineering 2024年第1期21卷 84-100页

作者： Zihan Xu qin Fang Yong Ren Chengju liu Robot and Artificial Intelligence Lab(RAIL) College of Electronic and Information EngineeringTongji UniversityShanghai 201804China Applied Technology College Soochow UniversitySuzhou 215000China

Compliance motion and footstep adjustment are active balance control strategies from learning human subconscious *** force estimation without direct end-actuator force measurement and the optimal footsteps based on complex analytical calculation are still challenging tasks for elementary and kid-size position-controlled *** this paper,an online compliant controller with Gravity Projection Observer(GPO),which can express the external force condition of perturbations by the estimated Projection of Gravity(PoG)with estimation covariance,is proposed for the realization of disturbance absorption,with which the robustness of the humanoid contact with environments can be *** fuzzy footstep planner based on capturability analysis is proposed,and the Model Predictive Control(MPC)is applied to generate the desired *** fuzzification rules are well-designed and give the corresponding control output responding to complex and changeable external *** validate the presented methods,a series of experiments on a real humanoid robot are *** results verify the effectiveness of the proposed balance control framework.

关键词： Biped walking Centroidal compliance Gravity projection observer Fuzzy footstep planner

Inorganic ionic polymerization:From biomineralization to materials manufacturing

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Nano Research 2024年第2期17卷 550-569页

作者： Yanhua Sang Kexin qin Ruikang Tang Zhaoming liu Department of Chemistry Zhejiang UniversityHangzhou 310058China

Biomineralization process regulates the growth of inorganic minerals by complex molecules,proteins,and cells,endowing bio-materials with marvels structures and excellent *** intricate structures and compositions found in biominerals have inspired scientists to design and synthesize numerous artificial biomimetic *** methodology for controlling the formation of inorganics plays a pivotal role in achieving biomimetic structures and ***,the current approach predominantly relies on the classical nucleation theory,which hinders the precise preparation of inorganic materials by replicating the biomineralization ***,the development of“inorganic ionic polymerization”strategy has enabled us to regulate the arrangement of inorganic ions from solution to solid phase,which establishes an artificial way to produce inorganic materials analogous to the biomineralization *** on inorganic ionic polymerization,a series of achievements have been realized for the biomimetic preparation,including moldable construction of inorganic materials,hard tissue regeneration,and high-performance biomimetic ***,the utilization of inorganic ionic polymerization has also facilitated the production of numerous advanced materials,including novel structures that exceed the current knowledge of materials *** inorganic ionic polymerization system provides new artificial strategies and methodologies for the controllable synthesis of inorganics,which mimics the biomineralization process,paving the way for the future development of more high-performance materials.

关键词： biomineralization inorganic ionic polymerization biomimetic materials crystal growth synthetic methodology

Constitutive modelling of concrete material subjected to low-velocity projectile impact:insights into damage mechanism and target resistance

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第2期25卷 161-182页

作者： Shen liu Xieping HUANG Xiangzhen KONG qin FANG Center for Hypergravity Experiment and Interdisciplinary Research Zhejiang UniversityHangzhou310058China Institute of Geotechnical Engineering Zhejiang UniversityHangzhou310058China State Key Laboratory of Disaster Prevention&Mitigation of Explosion&Impact Army Engineering University of PLANanjing210007China

This paper presents a numerical study to improve the understanding of the complex subject of penetration and perforation of concrete targets impacted by low-velocity *** main focus is on the damage mechanisms and the major factors that account for the target resistance of the *** improved continuous surface cap model recently proposed was *** model was first equipped with element erosion criteria and was adequately validated by comparisons with ballistic *** numerical simulations were carried out where the individual influence of tensile,shear,and volumetric behaviors(pore collapse)of a concrete target on its ballistic performance was *** demonstrated that cratering on the front face and scabbing on the rear face of the concrete target were mainly dominated by its tensile *** major target resistance came from the second tunneling stage which was primarily governed by the shear and volumetric behaviors of the ***,this study captured the pore collapse-induced damage phenomenon during the high-pressure tunneling stage,which has been extensively reported in experiments but has usually been neglected in previous numerical investigations.

关键词： Penetration Perforation Damage mechanism Target resistance Projectile impact Pore collapse

Reynolds-number scaling analysis on lift generation of a flapping and passive rotating wing with an inhomogeneous mass distribution

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Chinese Journal of Aeronautics 2024年第2期37卷 259-269页

作者： Suyang qin Haotian HANG Yang XIANG Hong liu J.C.Wu center for aerodynamics school of aeronautics and astronauticsshanghai jiao tong universityshanghai 200240china

Insects usually fly by passively rotating wings,which has been applied to the design of flapping-wing Micro-Air Vehicles(MAVs)to reduce mechanical *** this paper,a robotic passive rotating-wing model is designed to investigate wing kinematics and lift generation,which are measured by a high-speed camera and a force transducer,*** addition,flow fields are measured using the Particle Image Velocimetry(PIV).Experimental results demonstrate that passive rotating motion has a coordinative relationship with actively stroking *** the stroke amplitude or frequency increases,the rotating amplitude is *** characterize the active stroking motion,a driving Reynolds number Redrivingis defined,which varies from 68 to 366 in this *** the gravity center of the wing towards trailing ed ge induces the increase of additional torque M,which decreases the wing rotating amplitude and promotes the advance of wing *** find that the timing of wing rotation is gradually delayed and the mean lift coefficient C^(-)_(L)monotonously decreases as *** increasing the additional torque M,C^(-)_(L)is slightly improved and approaches to the lift coefficient of a real fruit fly at driving Re approximately equal to *** instantaneous lifts combined with the vortical structures further demonstrate that the lift generation associated with wing rotation is mainly attributed to the growth of the LeadingEdge Vortex(LEV)and the passive wake capture *** wake capture is influenced by LEV,reversal stroke motion and wing additional torque together,which can only maintain the lift at a high level for a considerable *** high-lift generation mechanisms of flapping and passive rotating flight could shed light on the simplified design of MAVs and the improvement of their aerodynamic performance.

关键词： Flapping flight Unsteady lift Passive rotation Vortex flow Leading-edge vortex