To objectively obtain the three-dimensional coordinates of the projectile fuze proximity explosion when projectile intersects the head of missile target, we propose a dynamic seven photoelectric detection screen test ...To objectively obtain the three-dimensional coordinates of the projectile fuze proximity explosion when projectile intersects the head of missile target, we propose a dynamic seven photoelectric detection screen test method, which is made up of six plane detection screens and a flash photoelectric dynamic detection screen. The three-dimensional coordinates calculation model of the projectile proximity explosion position based on seven plane detection screens with dynamic characteristics is established.According to the relation of the dynamic seven photoelectric detection screen planes and the time values,the analytical function of the projectile proximity explosion position parameters under non-linear motion is derived. The projectile signal filtering method based on discrete wavelet transform is explored in this work. Additionally, the projectile signal recognition algorithm using an improved particle swarm is proposed. Based on the characteristics of the time duration and the signal peak error for the projectile passing through the detection screen, the signals attribution of the same projectile passing through six detection screens are analyzed for obtaining precise time values of the same projectile passing through the detection screens. On the basis of the projectile fuze proximity explosion test, the linear motion model and the proposed non-linear motion model are used to calculate and compare the same group of projectiles proximity explosion position parameters. The comparison of test results verifies that the proposed test method and calculation model in this work accurately obtain the actual projectile proximity explosion position parameters.展开更多
In this paper, a transformation model named SARC(static-filter adjustment with restricted condition) is presented, which is more practical and more rigorous in theory and fitting any angle of rotation parameter. The t...In this paper, a transformation model named SARC(static-filter adjustment with restricted condition) is presented, which is more practical and more rigorous in theory and fitting any angle of rotation parameter. The transformation procedure is divided into 4 steps: ① the original and object coordinates can be regarded as observations with errors; ② rigorous formula is firstly deduced in order to compute the first approximation of the transformation parameters by use of four common points and the transformation equation is linearized; ③ calculate the most probable values and variances of the seven transformation parameters by SARC model; ④ to demonstrate validity of SARC , an example is given.展开更多
In wind power transmission via modular multilevel converter based high voltage direct current(MMCHVDC)systems,under traditional control strategies,MMC-HVDCcannot provide inertia support to the receiving-end grid(REG)d...In wind power transmission via modular multilevel converter based high voltage direct current(MMCHVDC)systems,under traditional control strategies,MMC-HVDCcannot provide inertia support to the receiving-end grid(REG)during disturbances.Moreover,due to the frequency decoupling between the two ends of the MMCHVDC,the sending-end wind farm(SEWF)cannot obtain the frequency variation information of the REG to provide inertia response.Therefore,this paper proposes a novel coordinated source-network-storage inertia control strategy based on wind power transmission via MMC-HVDC system.First,the grid-side MMC station(GS-MMC)maps the frequency variations of the REG to direct current(DC)voltage variations through the frequency mapping control,and uses submodule capacitor energy to provide inertial power.Then,the wind farm-side MMC station(WF-MMC)restores the DC voltage variations to frequency variations through the frequency restoration control and power loss compensation,providing real-time frequency information for the wind farm.Finally,based on real-time frequency information,thewind farmutilizes the rotor kinetic energy and energy storage to provide fast and lasting power support through the wind-storage coordinated inertia control strategy.Meanwhile,when the wind turbines withdraw from the inertia response phase,the energy storage can increase the power output to compensate for the power deficit,preventing secondary frequency drops.Furthermore,this paper uses small-signal analysis to determine the appropriate values for the key parameters of the proposed control strategy.A simulation model of the wind power transmission via MMCHVDC system is built in MATLAB/Simulink environment to validate and evaluate the proposed method.The results show that the proposed coordinated control strategy can effectively improve the system inertia level and avoid the secondary frequency drop under the load sudden increase condition.展开更多
Under the strategic framework of rural revitalization and agricultural modernization, Xinjiashan Specialty Coffee Base, located in Zaotang Village, Lujiang Town, Longyang District, Baoshan City, has been proactively i...Under the strategic framework of rural revitalization and agricultural modernization, Xinjiashan Specialty Coffee Base, located in Zaotang Village, Lujiang Town, Longyang District, Baoshan City, has been proactively investigating innovative models for agricultural development. Through extensive communication and collaboration, this base has established close partnerships with research institutions including Kunming University of Science and Technology, Baoshan University, and Yunnan Academy of Agricultural Sciences, with a commitment to thoroughly exploring the potential for resource recycling and ecological complementarity. An innovative four-in-one three-dimensional integrated planting system incorporating "coffee, bananas, green manure, and bees" has been implemented. Concurrently, technological and digital management strategies have been comprehensively integrated to improve planting efficiency. Under this model, the proportion of specialty coffee attains 71%, and the per-unit yield is 17% greater than that of the conventional planting model. This approach not only substantially enhances economic returns but also promotes the integrated development of ecological and social benefits, offering a valuable practical example and experiential reference for the specialty and sustainable advancement of the coffee industry in comparable regions.展开更多
Aerial surveys are dynamic and continuous processes,and there are different height distributions of the ground in the measurement area,which leads to problems such as overlapping measurement areas and inaccurate altit...Aerial surveys are dynamic and continuous processes,and there are different height distributions of the ground in the measurement area,which leads to problems such as overlapping measurement areas and inaccurate altitude correction during the survey process.Commonly used terrain correction methods are based on the concept of finite elementization of ground surface radioactive sources,using GPS coordinates,radar altitude,and ground elevation distribution information from aerial surveys,combined with the sourceless efficiency calibration method to construct a response matrix,which is then inverted for surface nuclide content.However,most of the sourceless efficiency calibration methods used are numerical calculations that consider the body detector as a point detector and do not consider the changes in intrinsic detection efficiency under different incident directions of gamma rays.Therefore,when the altitude of the measurement area varies significantly or the flight altitude of the aerial survey is relatively low,such sourceless efficiency calibration method calculations tend to have a large bias,which affects the accuracy of the terrain correction.To address the above problems,this study employs a novel sourceless efficiency calibration method based on the Boolean operation of the ray deposition process and simplifies the traditional body source measurement model to a surface source measurement model to achieve fast and accurate efficiency calibration.Then,through the discretization of the measurement process,the static measurement process is superposed as equivalent to the dynamic measurement process,and the dynamic measurement response matrix is built and optimized based on the calibration method.Finally,the PSO-MLEM algorithm was used to solve the dynamic measurement response matrix to achieve dynamic terrain correction of aerial survey data.Analysis of the Baiyun'ebo test area revealed that,after applying dynamic terrain correction,the inverted anomalies in uranium(eU),thorium(eTh),and potassium(K)concentrations were closer to ground measurements(within 5.72%-30.79%)and exhibited clearer anomaly boundaries compared to traditional height-based corrections.However,owing to the inherent statistical fluctuations and characteristics of matrix inversion,higher measurement values tend to absorb lower ones,potentially enlarging the anomalous regions.Nevertheless,the highanomaly regions after inversion largely coincided with the ground truth validation,demonstrating that the proposed method can effectively correct airborne gamma spectrometry data.展开更多
Cooperative pursuit poses challenges across natural,social,and technical systems,particularly when decentralized,slow-speed pursuers attempt to capture a high-speed evader with limited observation.Most existing contri...Cooperative pursuit poses challenges across natural,social,and technical systems,particularly when decentralized,slow-speed pursuers attempt to capture a high-speed evader with limited observation.Most existing contributions place the focus on the greedy pursuit of the evader,overlooking potential collaborations among pursuers.To tackle this issue,a decisionmaking framework of multi-agent coordinated reciprocity formation pursuit(MACRFP)via deep reinforcement learning is introduced.This framework integrates the actor-critic algorithm with the coordinated reciprocity mechanism to enhance the capability of capturing a faster evader.Initially,a local perception model is created by utilizing a cellular network to simulate limitations caused by obstacles.Next,the formation coalition of pursuit is guided by the Cartesian Oval,enabling dispersed pursuers to create a siege against the faster evader.Furthermore,a coordinated reciprocity model based on the coordination graph and the attention-based graph neural networks is developed,addressing the global coordination problem by estimating a reciprocity coefficient to adjust agents'rewards.Numerical simulations demonstrate the emergence of cooperative behaviors in cooperative besiegement,target tracking,and intelligent interception during the pursuit,indicating that the proposed algorithm enhances the feasibility and effectiveness of capturing a fast-escaping target by integrating coordinated reciprocity and coalition formation.展开更多
Grid-Forming(GFM)converters are prone to fault-induced overcurrent and power angle instability during grid fault-induced voltage sags.To address this,this paper develops a multi-loop coordinated fault ridethrough(FRT)...Grid-Forming(GFM)converters are prone to fault-induced overcurrent and power angle instability during grid fault-induced voltage sags.To address this,this paper develops a multi-loop coordinated fault ridethrough(FRT)control strategy based on a power outer loop and voltage-current inner loops,aiming to enhance the stability and current-limiting capability of GFM converters during grid fault conditions.During voltage sags,the GFM converter’s voltage source behavior is maintained by dynamically adjusting the reactive power reference to provide voltage support,thereby effectively suppressing the steady-state component of the fault current.To address the active power imbalance induced by voltage sags,a dynamic active power reference correction method based on apparent power is designed to mitigate power angle oscillations and limit transient current.Moreover,an adaptive virtual impedance loop is implemented to enhance dynamic transient current-limiting performance during the fault initiation phase.This approach improves the responsiveness of the inner loop and ensures safe system operation under various fault severities.Under asymmetric fault conditions,a negative-sequence reactive current compensation strategy is incorporated to further suppress negative-sequence voltage and improve voltage symmetry.The proposed control scheme enables coordinated operation of multiple control objectives,including voltage support,current suppression,and power angle stability,across different fault scenarios.Finally,MATLAB/Simulink simulation results validate the effectiveness of the proposed strategy,showcasing its superior performance in current limiting and power angle stability,thereby significantly enhancing the system’s fault ride-through capability.展开更多
According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing ...According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing differential equations are derived by the Hamilton's variational principle,and then solved by the iterative Separation-of-Variable(i SOV)method,which are applicable to arbitrary combinations of homogeneous Boundary Conditions(BCs).However,only the simply-support,clamped and cantilever panels are considered in this work for the sake of clarity.With the closed-form eigensolutions,the flutter frequency,flutter mode and flutter boundary are presented,and the effect of shear deformation and aerodynamic damping on flutter frequencies is investigated.Besides,the relation between panel energy and the work of aerodynamic load is discussed.The numerical comparisons reveal the following.(A)The flutter eigenvalues obtained by the present method are accurate,validated by the Finite Element Method(FEM)and the Galerkin method.(B)When the span-chord ratio is larger than 3,simplifying a 3D panel to 2D(two-dimensional)panel is reasonable and the relative differences of the flutter points predicted by the two models are less than one percent.(C)The reciprocal relationship between the mechanical energy of the panel and the work done by aerodynamic load is verified by using the present flutter eigenvalues and modes,further indicating the high accuracy of the present solutions.(D)The coupling of shear deformation and aerodynamic damping prevents frequency coalescing.展开更多
Facing the economic challenges of significant frequency regulation wear and tear on thermal power units and short energy storage lifespan in thermal-energy storage combined systems participating in grid primary freque...Facing the economic challenges of significant frequency regulation wear and tear on thermal power units and short energy storage lifespan in thermal-energy storage combined systems participating in grid primary frequency regulation(PFR),this paper proposes a novel hybrid energy storage system(HESS)control strategy based on Newton-Raphson optimization algorithm(NRBO)-VMD and a fuzzy neural network(FNN)for PFR.In the primary power allocation stage,the high inertia and slow response of thermal power units prevent them from promptly responding to the high-frequency components of PFR signals,leading to increased mechanical stress.To address the distinct response characteristics of thermal units and HESS,an NRBO-VMD based decomposition method for PFR signals is proposed,enabling a flexible system response to grid frequency deviations.Within the HESS,an adaptive coordinated control strategy and a State of Charge(SOC)self-recovery strategy are introduced.These strategies autonomously adjust the virtual inertia and droop coefficients based on the depth of frequency regulation and the real-time SOC.Furthermore,a FNN is constructed to perform secondary refinement of the internal power distribution within the HESS.Finally,simulations under various operational conditions demonstrate that the proposed strategy effectively mitigates frequent power adjustments of the thermal unit during PFR,adaptively achieves optimal power decomposition and distribution,maintains the flywheel energy storage’s SOC within an optimal range,and ensures the long-term stable operation of the HESS.展开更多
This paper proposes a state-of-the-art three-dimensional Voronoi cell finite element method(3D VCFEM)aimed at investigating the mechanical properties of particle-reinforced composites(PRCs)in space under different mic...This paper proposes a state-of-the-art three-dimensional Voronoi cell finite element method(3D VCFEM)aimed at investigating the mechanical properties of particle-reinforced composites(PRCs)in space under different microstructural properties.Firstly,the modified residual energy generalized function of 3D VCFEM was proposed by applying the hybrid stress element method,and the element format of the 3D Voronoi element was constructed.On this basis,the interaction between the matrix and the inclusions was considered,and the higher-order stress function including the interaction stress term was constructed.Secondly,to solve the difficulty of integrating easily due to the complexity and irregularity of the integration region in space,Delaunay tetrahedra were introduced within the 3D Voronoi element for mesh refinement.It simplified the integration process.Finally,to verify the accuracy and efficiency of the 3D VCFEM model,comparative models of 3D VCFENM and FEM were established for analysis and discussion.The stress field and strain field were compared and analyzed for the first time.An example was also given for the presence of a large number of randomly distributed inclusion particles.The results showed that under the same accuracy,3D VCFEM had the advantages of convenient mesh delineation and high computational efficiency compared with FEM,which provided a new way of thinking to analyze the actual PCRs.展开更多
The authors extend the marginal coordinate test for predictor contribution(Cook,2004)to the case with multivariate responses.Instead of explicitly specifying the link functions between the responses and the predictors...The authors extend the marginal coordinate test for predictor contribution(Cook,2004)to the case with multivariate responses.Instead of explicitly specifying the link functions between the responses and the predictors,an asymptotic test is proposed under the normality assumption of the predictors as well as an asymmetry assumption about the unknown regression mean function.When these assumptions are violated,the asymptotic test with elliptical trimming and clustering is still valid with desirable numerical performances.展开更多
Accurate and real-time traffic-sign detection is a cornerstone of Advanced Driver-Assistance Systems(ADAS)and autonomous vehicles.However,existing one-stage detectors miss distant signs,and two-stage pipelines are imp...Accurate and real-time traffic-sign detection is a cornerstone of Advanced Driver-Assistance Systems(ADAS)and autonomous vehicles.However,existing one-stage detectors miss distant signs,and two-stage pipelines are impractical for embedded deployment.To address this issue,we present YOLO-SMM,a lightweight two-stage framework.This framework is designed to augment the YOLOv8 baseline with three targeted modules.(1)SlimNeck replaces PAN/FPN with a CSP-OSA/GSConv fusion block,reducing parameters and FLOPs without compromising multi-scale detail.(2)The MCA model introduces row-and column-aware weights to selectively amplify small sign regions in cluttered scenes.(3)MPDIoU augments CIoU loss with a corner-distance term,supplying stable gradients for sub-20-pixel boxes and tightening localization.An evaluation of YOLO-SMMon the German Traffic Sign Recognition Benchmark(GTSRB)revealed that it attained 96.3% mAP50 and 93.1% mAP50-90 at a rate of 90.6 frames per second(FPS).This represents an improvement of+1.0% over previous performance benchmarks.Them APat 64×64 resolution was found to be 50% of the maximum attainable value,with an FPS of+8.3 when compared to YOLOv8.This result indicates superior performance in terms of accuracy and speed compared to YOLOv7,YOLOv5,RetinaNet,EfficientDet,and Faster R-CNN,all of which were operated under equivalent conditions.展开更多
This study explores the quasi-real time inversion principle and precision estimation of three-dimensional coordinates of the epicenter, trigger time and magnitude of earthquakes with the aim to improve traditional met...This study explores the quasi-real time inversion principle and precision estimation of three-dimensional coordinates of the epicenter, trigger time and magnitude of earthquakes with the aim to improve traditional methods, which are flawed due to missing information or distortion in the seismograph records. The epicenter, trigger time and magnitude from the Lushan earthquake are inverted and analyzed based on high-frequency GNSS data. The inversion results achieved a high precision, which are consistent with the data published by the China Earthquake Administration. Moreover, it has been proven that the inversion method has good theoretical value and excellent application prospects.展开更多
A new three-dimensional fundamental solution to the Stokes flow was proposed by transforming the solid harmonic functions in Lamb's solution into expressions in terms Of the oblate spheroidal coordinates. These fu...A new three-dimensional fundamental solution to the Stokes flow was proposed by transforming the solid harmonic functions in Lamb's solution into expressions in terms Of the oblate spheroidal coordinates. These fundamental solutions are advantageous in treating flows past an arbitrary number of arbitrarily positioned and oriented oblate spheroids. The least squares technique was adopted herein so that the convergence difficulties often encountered in solving three-dimensional problems were completely avoided. The examples demonstrate that present approach is highly accurate, consistently stable and computationally efficient. The oblate spheroid may be used to model a variety of particle shapes between a circular disk and a sphere. For the first time, the effect of various geometric factors on the forces and torques exerted on two oblate spheroids were systematically studied by using the proposed fundamental solutions. The generality of this approach was illustrated by two problems of three spheroids.展开更多
Starting from the finite rotation group,the author makes a penetrating study of 4 to 7-dimensional hypercube so that we have acquired the projection models of 4 to 7-dimeneional spatial rectangular coordinate systems ...Starting from the finite rotation group,the author makes a penetrating study of 4 to 7-dimensional hypercube so that we have acquired the projection models of 4 to 7-dimeneional spatial rectangular coordinate systems into the three-dimensional space to have the 4 to 7-dimensional geometric figures demonstrated correctly.展开更多
The title coordination polymer including two crystallographically independent Co2＋ ions is hydrothermally synthesized, in which the Co（1） 2＋ ion is four-coordinated by two carboxylate oxygen atoms from two differe...The title coordination polymer including two crystallographically independent Co2＋ ions is hydrothermally synthesized, in which the Co（1） 2＋ ion is four-coordinated by two carboxylate oxygen atoms from two different 5-（benzoic acid-4-yldiazenyl）isophthalate （byip3-） anions and two nitrogen atoms from two distinct 1,4-bis（imidazol-1-ylmethyl） benzene （bix） ligands displaying a tetrahedral geometry. The Co（2） 2＋ ion is six-coordinated by two water molecules at the apical positions, and two carboxylate oxygen atoms and two nitrogen atoms at the equatorial positions, affording a slightly distorted octahedron. Two Co（1）2＋ and two Co（2）2＋ ions are linked together by four byip3- anions forming a 44-membered motif and these motifs are further arranged into a three-dimensional framework through bix ligands along the a axis with a larger channel （ca. 22.70×11.01）. Each individual network interpenetrates with the other identical network in a parallel fashion to generate a 2-fold interpenetrating array with the {62.84}{63}2{64.82}2 topology.展开更多
A novel coordination polymer [Zn2（BTA）2（TDC）]n（HBTA = benzotriazole, H2TDC = thiophene-2,5-dicarboxylic acid） has been synthesized by the reaction of zinc（Ⅱ）, H2TDC and HBTA. This compound is fully structural...A novel coordination polymer [Zn2（BTA）2（TDC）]n（HBTA = benzotriazole, H2TDC = thiophene-2,5-dicarboxylic acid） has been synthesized by the reaction of zinc（Ⅱ）, H2TDC and HBTA. This compound is fully structurally characterized by elemental analysis, IR, and single-crystal X-ray crystallography. The bulk new materials were further identified by X-ray powder diffraction. Compound 1 crystallizes in the orthorhombic system, space group Pbcn, with a = 9.8825（8）, b = 9.4047（8）, c = 20.5567（17） , V = 1910.6（3） -3, C（18）H（10）N6O4SZn2, Mr = 537.12, Dc = 1.867 g/cm-3, μ（MoK α） = 2.662 mm-（-1）, F（000） = 1072, Z = 4, S = 1.058, the final R = 0.0201 and w R = 0.0530 for 1700 observed reflections（I 2σ（I））. Its compositional stability and photoluminescence properties were further investigated to establish the structure-property relationships. Structural analysis reveals that this compound is a 3D（4, 4）-connected framework with the（6-6）（6-4·8-2） topology.展开更多
A new metal-organic coordination polymer [Zn1.5（PDB）（bix）0.5（μ2-OH）]2n 1 （H2PDB = pyridine-3,4-dicarboxylic acid, bix = 1,4-bis（imidazol-1-ylmethyl）-benzene） has been hydrothermally synthesized and structur...A new metal-organic coordination polymer [Zn1.5（PDB）（bix）0.5（μ2-OH）]2n 1 （H2PDB = pyridine-3,4-dicarboxylic acid, bix = 1,4-bis（imidazol-1-ylmethyl）-benzene） has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P2/c with a = 7.411（2）, b = 7.848（3）, c = 25.048（8）, V = 1451.8（8）3, C28H22N6O10Zn3, Mr = 798.63, Dc = 1.827 g/cm3, μ（MoKα） = 2.529 mm-1, F（000） = 804, Z = 2, the final R = 0.0440 and wR = 0.1035 for 1952 observed reflections （I 2σ（I））. It exhibits a three-dimensional framework structure. Moreover, its luminescent property has been investigated in the solid state.展开更多
Two coordination polymers with 1,4-benzenedicarboxylic acid（H2BDC） ligand, namely, [Tb3（BDC）（4.5）（H2O）（DMF）2]n （1） and [Tb2（BDC）3（H2O）2（DMF）2]n（2）, have been synthesized and characterized. Both com...Two coordination polymers with 1,4-benzenedicarboxylic acid（H2BDC） ligand, namely, [Tb3（BDC）（4.5）（H2O）（DMF）2]n （1） and [Tb2（BDC）3（H2O）2（DMF）2]n（2）, have been synthesized and characterized. Both compounds crystallize in the triclinic system, space group P1. For compound 1, a = 10.8528（5）, b = 12.2516（5）, c = 16.9031（7） A, α = 104.462（1）, β = 93.659（1）, γ = 101.404（1）°, V = 2118.1（2） A^3, Z = 2, C（42）H（34）N2O（21）Tb3, Mr = 1379.47, Dc = 2.163 g/cm^3, μ = 5.045 mm^-1, F（000） = 1326, the final R = 0.0212 and wR = 0.0570 for 8592 observed reflections with I 〉 2σ（I）. For compound 2, a = 8.547（1）, b = 10.170（1）, c = 11.192（1）A？, α = 65.531（1）, β = 71.886（1）, γ = 78.796（1）°, V = 839.2（2） A^3, Z = 1, C（30）H（30）N2O（16）Tb2, Mr = 992.40, Dc = 1.964 g/cm^3, μ = 4.257 mm^-1, F（000） = 482, the final R = 0.0220 and wR = 0.0649 for 3626 observed reflections with I 〉 2σ（I）. The compounds exhibit different structural topologies depending on the nature of templating agents in the reactions though the templating agents are not incorporated in the final solids. Compound 1 exhibits a three-dimensional（3D） framework based on the rod-shaped terbium-carboxylate building blocks constructed from linear trinuclear Tb3 units. Compound 2 has a 3D framework containing two interpenetrating pcu topological networks based on the 6-connected dinuclear Tb2 secondary building units. Photoluminescence studies show both compounds exhibit typical Tb（Ⅲ） luminescence emissions. An efficient ligand-to-Tb（Ⅲ） energy transfer is observed in the emission spectra for both compounds.展开更多
A new metal-organic coordination polymer [Ni2（NIPH）2（bimb）2.5（H2O）] n·3nH2O 1 （H2NIPH = 5-nitroisophthalic acid, bimb = 1,4-bis（imidazol-1-yl）-butane） has been hydrothermally synthesized and structurall...A new metal-organic coordination polymer [Ni2（NIPH）2（bimb）2.5（H2O）] n·3nH2O 1 （H2NIPH = 5-nitroisophthalic acid, bimb = 1,4-bis（imidazol-1-yl）-butane） has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction. The title complex crystallizes in the orthorhombic system, space group P4（1）2（1）2 with a = 17.3533（16）, b = 17.3533（16）, c = 30.802（6）A, V= 9275（2）A^3, C41HagN12Ni2O16, Mr = 1083.34, Dc = 1.552 g/cm^3, p（MoKa） = 0.897 mm^-1, F（000） = 4504, Z = 8, the final R = 0.0383 and wR = 0.0952 for 7343 observed reflections （I〉 2σ（I））. It exhibits a three-dimensional network structure.展开更多
基金supported by Project of the National Natural Science Foundation of China (No.62073256, 61773305)the Key Science and Technology Program of Shaanxi Province (No.2020GY-125)Xi’an Science and Technology Innovation talent service enterprise project (No.2020KJRC0041)。
文摘To objectively obtain the three-dimensional coordinates of the projectile fuze proximity explosion when projectile intersects the head of missile target, we propose a dynamic seven photoelectric detection screen test method, which is made up of six plane detection screens and a flash photoelectric dynamic detection screen. The three-dimensional coordinates calculation model of the projectile proximity explosion position based on seven plane detection screens with dynamic characteristics is established.According to the relation of the dynamic seven photoelectric detection screen planes and the time values,the analytical function of the projectile proximity explosion position parameters under non-linear motion is derived. The projectile signal filtering method based on discrete wavelet transform is explored in this work. Additionally, the projectile signal recognition algorithm using an improved particle swarm is proposed. Based on the characteristics of the time duration and the signal peak error for the projectile passing through the detection screen, the signals attribution of the same projectile passing through six detection screens are analyzed for obtaining precise time values of the same projectile passing through the detection screens. On the basis of the projectile fuze proximity explosion test, the linear motion model and the proposed non-linear motion model are used to calculate and compare the same group of projectiles proximity explosion position parameters. The comparison of test results verifies that the proposed test method and calculation model in this work accurately obtain the actual projectile proximity explosion position parameters.
文摘In this paper, a transformation model named SARC(static-filter adjustment with restricted condition) is presented, which is more practical and more rigorous in theory and fitting any angle of rotation parameter. The transformation procedure is divided into 4 steps: ① the original and object coordinates can be regarded as observations with errors; ② rigorous formula is firstly deduced in order to compute the first approximation of the transformation parameters by use of four common points and the transformation equation is linearized; ③ calculate the most probable values and variances of the seven transformation parameters by SARC model; ④ to demonstrate validity of SARC , an example is given.
基金funded by State Grid Corporation of China Central Branch Technology Project(52140024000C).
文摘In wind power transmission via modular multilevel converter based high voltage direct current(MMCHVDC)systems,under traditional control strategies,MMC-HVDCcannot provide inertia support to the receiving-end grid(REG)during disturbances.Moreover,due to the frequency decoupling between the two ends of the MMCHVDC,the sending-end wind farm(SEWF)cannot obtain the frequency variation information of the REG to provide inertia response.Therefore,this paper proposes a novel coordinated source-network-storage inertia control strategy based on wind power transmission via MMC-HVDC system.First,the grid-side MMC station(GS-MMC)maps the frequency variations of the REG to direct current(DC)voltage variations through the frequency mapping control,and uses submodule capacitor energy to provide inertial power.Then,the wind farm-side MMC station(WF-MMC)restores the DC voltage variations to frequency variations through the frequency restoration control and power loss compensation,providing real-time frequency information for the wind farm.Finally,based on real-time frequency information,thewind farmutilizes the rotor kinetic energy and energy storage to provide fast and lasting power support through the wind-storage coordinated inertia control strategy.Meanwhile,when the wind turbines withdraw from the inertia response phase,the energy storage can increase the power output to compensate for the power deficit,preventing secondary frequency drops.Furthermore,this paper uses small-signal analysis to determine the appropriate values for the key parameters of the proposed control strategy.A simulation model of the wind power transmission via MMCHVDC system is built in MATLAB/Simulink environment to validate and evaluate the proposed method.The results show that the proposed coordinated control strategy can effectively improve the system inertia level and avoid the secondary frequency drop under the load sudden increase condition.
文摘Under the strategic framework of rural revitalization and agricultural modernization, Xinjiashan Specialty Coffee Base, located in Zaotang Village, Lujiang Town, Longyang District, Baoshan City, has been proactively investigating innovative models for agricultural development. Through extensive communication and collaboration, this base has established close partnerships with research institutions including Kunming University of Science and Technology, Baoshan University, and Yunnan Academy of Agricultural Sciences, with a commitment to thoroughly exploring the potential for resource recycling and ecological complementarity. An innovative four-in-one three-dimensional integrated planting system incorporating "coffee, bananas, green manure, and bees" has been implemented. Concurrently, technological and digital management strategies have been comprehensively integrated to improve planting efficiency. Under this model, the proportion of specialty coffee attains 71%, and the per-unit yield is 17% greater than that of the conventional planting model. This approach not only substantially enhances economic returns but also promotes the integrated development of ecological and social benefits, offering a valuable practical example and experiential reference for the specialty and sustainable advancement of the coffee industry in comparable regions.
基金supported by the National Key Research and Development Program(No.2022YFC2807400)the National Natural Science Foundation of China(Nos.12265003 and 12205044)。
文摘Aerial surveys are dynamic and continuous processes,and there are different height distributions of the ground in the measurement area,which leads to problems such as overlapping measurement areas and inaccurate altitude correction during the survey process.Commonly used terrain correction methods are based on the concept of finite elementization of ground surface radioactive sources,using GPS coordinates,radar altitude,and ground elevation distribution information from aerial surveys,combined with the sourceless efficiency calibration method to construct a response matrix,which is then inverted for surface nuclide content.However,most of the sourceless efficiency calibration methods used are numerical calculations that consider the body detector as a point detector and do not consider the changes in intrinsic detection efficiency under different incident directions of gamma rays.Therefore,when the altitude of the measurement area varies significantly or the flight altitude of the aerial survey is relatively low,such sourceless efficiency calibration method calculations tend to have a large bias,which affects the accuracy of the terrain correction.To address the above problems,this study employs a novel sourceless efficiency calibration method based on the Boolean operation of the ray deposition process and simplifies the traditional body source measurement model to a surface source measurement model to achieve fast and accurate efficiency calibration.Then,through the discretization of the measurement process,the static measurement process is superposed as equivalent to the dynamic measurement process,and the dynamic measurement response matrix is built and optimized based on the calibration method.Finally,the PSO-MLEM algorithm was used to solve the dynamic measurement response matrix to achieve dynamic terrain correction of aerial survey data.Analysis of the Baiyun'ebo test area revealed that,after applying dynamic terrain correction,the inverted anomalies in uranium(eU),thorium(eTh),and potassium(K)concentrations were closer to ground measurements(within 5.72%-30.79%)and exhibited clearer anomaly boundaries compared to traditional height-based corrections.However,owing to the inherent statistical fluctuations and characteristics of matrix inversion,higher measurement values tend to absorb lower ones,potentially enlarging the anomalous regions.Nevertheless,the highanomaly regions after inversion largely coincided with the ground truth validation,demonstrating that the proposed method can effectively correct airborne gamma spectrometry data.
基金supported by the National Natural Science Foundation of China(72371052,71871042)。
文摘Cooperative pursuit poses challenges across natural,social,and technical systems,particularly when decentralized,slow-speed pursuers attempt to capture a high-speed evader with limited observation.Most existing contributions place the focus on the greedy pursuit of the evader,overlooking potential collaborations among pursuers.To tackle this issue,a decisionmaking framework of multi-agent coordinated reciprocity formation pursuit(MACRFP)via deep reinforcement learning is introduced.This framework integrates the actor-critic algorithm with the coordinated reciprocity mechanism to enhance the capability of capturing a faster evader.Initially,a local perception model is created by utilizing a cellular network to simulate limitations caused by obstacles.Next,the formation coalition of pursuit is guided by the Cartesian Oval,enabling dispersed pursuers to create a siege against the faster evader.Furthermore,a coordinated reciprocity model based on the coordination graph and the attention-based graph neural networks is developed,addressing the global coordination problem by estimating a reciprocity coefficient to adjust agents'rewards.Numerical simulations demonstrate the emergence of cooperative behaviors in cooperative besiegement,target tracking,and intelligent interception during the pursuit,indicating that the proposed algorithm enhances the feasibility and effectiveness of capturing a fast-escaping target by integrating coordinated reciprocity and coalition formation.
文摘Grid-Forming(GFM)converters are prone to fault-induced overcurrent and power angle instability during grid fault-induced voltage sags.To address this,this paper develops a multi-loop coordinated fault ridethrough(FRT)control strategy based on a power outer loop and voltage-current inner loops,aiming to enhance the stability and current-limiting capability of GFM converters during grid fault conditions.During voltage sags,the GFM converter’s voltage source behavior is maintained by dynamically adjusting the reactive power reference to provide voltage support,thereby effectively suppressing the steady-state component of the fault current.To address the active power imbalance induced by voltage sags,a dynamic active power reference correction method based on apparent power is designed to mitigate power angle oscillations and limit transient current.Moreover,an adaptive virtual impedance loop is implemented to enhance dynamic transient current-limiting performance during the fault initiation phase.This approach improves the responsiveness of the inner loop and ensures safe system operation under various fault severities.Under asymmetric fault conditions,a negative-sequence reactive current compensation strategy is incorporated to further suppress negative-sequence voltage and improve voltage symmetry.The proposed control scheme enables coordinated operation of multiple control objectives,including voltage support,current suppression,and power angle stability,across different fault scenarios.Finally,MATLAB/Simulink simulation results validate the effectiveness of the proposed strategy,showcasing its superior performance in current limiting and power angle stability,thereby significantly enhancing the system’s fault ride-through capability.
基金support of the National Natural Science Foundation of China(No.12172023)。
文摘According to the Mindlin plate theory and the first-order piston theory,this work obtains accurate closed-form eigensolutions for the flutter problem of three-dimensional(3D)rectangular laminated panels.The governing differential equations are derived by the Hamilton's variational principle,and then solved by the iterative Separation-of-Variable(i SOV)method,which are applicable to arbitrary combinations of homogeneous Boundary Conditions(BCs).However,only the simply-support,clamped and cantilever panels are considered in this work for the sake of clarity.With the closed-form eigensolutions,the flutter frequency,flutter mode and flutter boundary are presented,and the effect of shear deformation and aerodynamic damping on flutter frequencies is investigated.Besides,the relation between panel energy and the work of aerodynamic load is discussed.The numerical comparisons reveal the following.(A)The flutter eigenvalues obtained by the present method are accurate,validated by the Finite Element Method(FEM)and the Galerkin method.(B)When the span-chord ratio is larger than 3,simplifying a 3D panel to 2D(two-dimensional)panel is reasonable and the relative differences of the flutter points predicted by the two models are less than one percent.(C)The reciprocal relationship between the mechanical energy of the panel and the work done by aerodynamic load is verified by using the present flutter eigenvalues and modes,further indicating the high accuracy of the present solutions.(D)The coupling of shear deformation and aerodynamic damping prevents frequency coalescing.
基金supported by the Lanzhou Science and Technology Plan Project(XM1753694781389).
文摘Facing the economic challenges of significant frequency regulation wear and tear on thermal power units and short energy storage lifespan in thermal-energy storage combined systems participating in grid primary frequency regulation(PFR),this paper proposes a novel hybrid energy storage system(HESS)control strategy based on Newton-Raphson optimization algorithm(NRBO)-VMD and a fuzzy neural network(FNN)for PFR.In the primary power allocation stage,the high inertia and slow response of thermal power units prevent them from promptly responding to the high-frequency components of PFR signals,leading to increased mechanical stress.To address the distinct response characteristics of thermal units and HESS,an NRBO-VMD based decomposition method for PFR signals is proposed,enabling a flexible system response to grid frequency deviations.Within the HESS,an adaptive coordinated control strategy and a State of Charge(SOC)self-recovery strategy are introduced.These strategies autonomously adjust the virtual inertia and droop coefficients based on the depth of frequency regulation and the real-time SOC.Furthermore,a FNN is constructed to perform secondary refinement of the internal power distribution within the HESS.Finally,simulations under various operational conditions demonstrate that the proposed strategy effectively mitigates frequent power adjustments of the thermal unit during PFR,adaptively achieves optimal power decomposition and distribution,maintains the flywheel energy storage’s SOC within an optimal range,and ensures the long-term stable operation of the HESS.
基金funded by the National Natural Science Foundation of China(Grant No.12227801).
文摘This paper proposes a state-of-the-art three-dimensional Voronoi cell finite element method(3D VCFEM)aimed at investigating the mechanical properties of particle-reinforced composites(PRCs)in space under different microstructural properties.Firstly,the modified residual energy generalized function of 3D VCFEM was proposed by applying the hybrid stress element method,and the element format of the 3D Voronoi element was constructed.On this basis,the interaction between the matrix and the inclusions was considered,and the higher-order stress function including the interaction stress term was constructed.Secondly,to solve the difficulty of integrating easily due to the complexity and irregularity of the integration region in space,Delaunay tetrahedra were introduced within the 3D Voronoi element for mesh refinement.It simplified the integration process.Finally,to verify the accuracy and efficiency of the 3D VCFEM model,comparative models of 3D VCFENM and FEM were established for analysis and discussion.The stress field and strain field were compared and analyzed for the first time.An example was also given for the presence of a large number of randomly distributed inclusion particles.The results showed that under the same accuracy,3D VCFEM had the advantages of convenient mesh delineation and high computational efficiency compared with FEM,which provided a new way of thinking to analyze the actual PCRs.
文摘The authors extend the marginal coordinate test for predictor contribution(Cook,2004)to the case with multivariate responses.Instead of explicitly specifying the link functions between the responses and the predictors,an asymptotic test is proposed under the normality assumption of the predictors as well as an asymmetry assumption about the unknown regression mean function.When these assumptions are violated,the asymptotic test with elliptical trimming and clustering is still valid with desirable numerical performances.
基金supported by University of Malaya and Ministry of High Education-Malaysia via Fundamental Research Grant Scheme No.FRGS/1/2023/TK10/UM/02/3.
文摘Accurate and real-time traffic-sign detection is a cornerstone of Advanced Driver-Assistance Systems(ADAS)and autonomous vehicles.However,existing one-stage detectors miss distant signs,and two-stage pipelines are impractical for embedded deployment.To address this issue,we present YOLO-SMM,a lightweight two-stage framework.This framework is designed to augment the YOLOv8 baseline with three targeted modules.(1)SlimNeck replaces PAN/FPN with a CSP-OSA/GSConv fusion block,reducing parameters and FLOPs without compromising multi-scale detail.(2)The MCA model introduces row-and column-aware weights to selectively amplify small sign regions in cluttered scenes.(3)MPDIoU augments CIoU loss with a corner-distance term,supplying stable gradients for sub-20-pixel boxes and tightening localization.An evaluation of YOLO-SMMon the German Traffic Sign Recognition Benchmark(GTSRB)revealed that it attained 96.3% mAP50 and 93.1% mAP50-90 at a rate of 90.6 frames per second(FPS).This represents an improvement of+1.0% over previous performance benchmarks.Them APat 64×64 resolution was found to be 50% of the maximum attainable value,with an FPS of+8.3 when compared to YOLOv8.This result indicates superior performance in terms of accuracy and speed compared to YOLOv7,YOLOv5,RetinaNet,EfficientDet,and Faster R-CNN,all of which were operated under equivalent conditions.
基金National Natural Science Foundation under Grant No.51574201Opening Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)under Grant No.SKLGP2016K017+2 种基金Open Research Fund by Sichuan Engineering Research Center for Emergency Mapping&Disaster Reduction under Grant No.K2015B008The State Administration of Work Safety under Grant No.2014_3335Soft Science Research Projects in Sichuan Province under Grant No.2015zr0049
文摘This study explores the quasi-real time inversion principle and precision estimation of three-dimensional coordinates of the epicenter, trigger time and magnitude of earthquakes with the aim to improve traditional methods, which are flawed due to missing information or distortion in the seismograph records. The epicenter, trigger time and magnitude from the Lushan earthquake are inverted and analyzed based on high-frequency GNSS data. The inversion results achieved a high precision, which are consistent with the data published by the China Earthquake Administration. Moreover, it has been proven that the inversion method has good theoretical value and excellent application prospects.
文摘A new three-dimensional fundamental solution to the Stokes flow was proposed by transforming the solid harmonic functions in Lamb's solution into expressions in terms Of the oblate spheroidal coordinates. These fundamental solutions are advantageous in treating flows past an arbitrary number of arbitrarily positioned and oriented oblate spheroids. The least squares technique was adopted herein so that the convergence difficulties often encountered in solving three-dimensional problems were completely avoided. The examples demonstrate that present approach is highly accurate, consistently stable and computationally efficient. The oblate spheroid may be used to model a variety of particle shapes between a circular disk and a sphere. For the first time, the effect of various geometric factors on the forces and torques exerted on two oblate spheroids were systematically studied by using the proposed fundamental solutions. The generality of this approach was illustrated by two problems of three spheroids.
文摘Starting from the finite rotation group,the author makes a penetrating study of 4 to 7-dimensional hypercube so that we have acquired the projection models of 4 to 7-dimeneional spatial rectangular coordinate systems into the three-dimensional space to have the 4 to 7-dimensional geometric figures demonstrated correctly.
基金Supported by the Natural Science Foundation of Henan Province (No. 102300410021 and 102300410093)
文摘The title coordination polymer including two crystallographically independent Co2＋ ions is hydrothermally synthesized, in which the Co（1） 2＋ ion is four-coordinated by two carboxylate oxygen atoms from two different 5-（benzoic acid-4-yldiazenyl）isophthalate （byip3-） anions and two nitrogen atoms from two distinct 1,4-bis（imidazol-1-ylmethyl） benzene （bix） ligands displaying a tetrahedral geometry. The Co（2） 2＋ ion is six-coordinated by two water molecules at the apical positions, and two carboxylate oxygen atoms and two nitrogen atoms at the equatorial positions, affording a slightly distorted octahedron. Two Co（1）2＋ and two Co（2）2＋ ions are linked together by four byip3- anions forming a 44-membered motif and these motifs are further arranged into a three-dimensional framework through bix ligands along the a axis with a larger channel （ca. 22.70×11.01）. Each individual network interpenetrates with the other identical network in a parallel fashion to generate a 2-fold interpenetrating array with the {62.84}{63}2{64.82}2 topology.
基金Supported by the Science and technology development plan of Jilin province(20150520006JH)Science and technology research project of Education Department of Jilin province(2016219)
文摘A novel coordination polymer [Zn2（BTA）2（TDC）]n（HBTA = benzotriazole, H2TDC = thiophene-2,5-dicarboxylic acid） has been synthesized by the reaction of zinc（Ⅱ）, H2TDC and HBTA. This compound is fully structurally characterized by elemental analysis, IR, and single-crystal X-ray crystallography. The bulk new materials were further identified by X-ray powder diffraction. Compound 1 crystallizes in the orthorhombic system, space group Pbcn, with a = 9.8825（8）, b = 9.4047（8）, c = 20.5567（17） , V = 1910.6（3） -3, C（18）H（10）N6O4SZn2, Mr = 537.12, Dc = 1.867 g/cm-3, μ（MoK α） = 2.662 mm-（-1）, F（000） = 1072, Z = 4, S = 1.058, the final R = 0.0201 and w R = 0.0530 for 1700 observed reflections（I 2σ（I））. Its compositional stability and photoluminescence properties were further investigated to establish the structure-property relationships. Structural analysis reveals that this compound is a 3D（4, 4）-connected framework with the（6-6）（6-4·8-2） topology.
基金Supported by the Science and Technology Development Project of Jilin Provincial Science&Technology Department(201205080)the Science and Technology Research Projects of the Education Department of Jilin Province(2012.358)
文摘A new metal-organic coordination polymer [Zn1.5（PDB）（bix）0.5（μ2-OH）]2n 1 （H2PDB = pyridine-3,4-dicarboxylic acid, bix = 1,4-bis（imidazol-1-ylmethyl）-benzene） has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction. The title compound crystallizes in the monoclinic system, space group P2/c with a = 7.411（2）, b = 7.848（3）, c = 25.048（8）, V = 1451.8（8）3, C28H22N6O10Zn3, Mr = 798.63, Dc = 1.827 g/cm3, μ（MoKα） = 2.529 mm-1, F（000） = 804, Z = 2, the final R = 0.0440 and wR = 0.1035 for 1952 observed reflections （I 2σ（I））. It exhibits a three-dimensional framework structure. Moreover, its luminescent property has been investigated in the solid state.
基金Supported by the NNSFC(21361011)the Provincial Natural Science Foundation of Jiangxi(20151BAB203002)+1 种基金the Project of Education Department of Jiangxi Province(GJJ14235)the Open Project Program of Key Laboratory of Functional Small Organic Molecule,Ministry of Education,Jiangxi Normal University(KLFS-KF-201412)
文摘Two coordination polymers with 1,4-benzenedicarboxylic acid（H2BDC） ligand, namely, [Tb3（BDC）（4.5）（H2O）（DMF）2]n （1） and [Tb2（BDC）3（H2O）2（DMF）2]n（2）, have been synthesized and characterized. Both compounds crystallize in the triclinic system, space group P1. For compound 1, a = 10.8528（5）, b = 12.2516（5）, c = 16.9031（7） A, α = 104.462（1）, β = 93.659（1）, γ = 101.404（1）°, V = 2118.1（2） A^3, Z = 2, C（42）H（34）N2O（21）Tb3, Mr = 1379.47, Dc = 2.163 g/cm^3, μ = 5.045 mm^-1, F（000） = 1326, the final R = 0.0212 and wR = 0.0570 for 8592 observed reflections with I 〉 2σ（I）. For compound 2, a = 8.547（1）, b = 10.170（1）, c = 11.192（1）A？, α = 65.531（1）, β = 71.886（1）, γ = 78.796（1）°, V = 839.2（2） A^3, Z = 1, C（30）H（30）N2O（16）Tb2, Mr = 992.40, Dc = 1.964 g/cm^3, μ = 4.257 mm^-1, F（000） = 482, the final R = 0.0220 and wR = 0.0649 for 3626 observed reflections with I 〉 2σ（I）. The compounds exhibit different structural topologies depending on the nature of templating agents in the reactions though the templating agents are not incorporated in the final solids. Compound 1 exhibits a three-dimensional（3D） framework based on the rod-shaped terbium-carboxylate building blocks constructed from linear trinuclear Tb3 units. Compound 2 has a 3D framework containing two interpenetrating pcu topological networks based on the 6-connected dinuclear Tb2 secondary building units. Photoluminescence studies show both compounds exhibit typical Tb（Ⅲ） luminescence emissions. An efficient ligand-to-Tb（Ⅲ） energy transfer is observed in the emission spectra for both compounds.
基金supported by the Science and Technology Development Project of Jilin Provincial Science & Technology Department (201205080)
文摘A new metal-organic coordination polymer [Ni2（NIPH）2（bimb）2.5（H2O）] n·3nH2O 1 （H2NIPH = 5-nitroisophthalic acid, bimb = 1,4-bis（imidazol-1-yl）-butane） has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction. The title complex crystallizes in the orthorhombic system, space group P4（1）2（1）2 with a = 17.3533（16）, b = 17.3533（16）, c = 30.802（6）A, V= 9275（2）A^3, C41HagN12Ni2O16, Mr = 1083.34, Dc = 1.552 g/cm^3, p（MoKa） = 0.897 mm^-1, F（000） = 4504, Z = 8, the final R = 0.0383 and wR = 0.0952 for 7343 observed reflections （I〉 2σ（I））. It exhibits a three-dimensional network structure.
