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
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
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
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 [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
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
A new coordination polymer, [Zn2（m-bix）（p-bdc）2] （1）, was synthesized under hydrothermal conditions by a reaction of 1,3-bis（imidazol-l-ylmethyl）benzene （m-bix）, 1,3-benzene- dicarboxylic acid （H2p-bdc） an...A new coordination polymer, [Zn2（m-bix）（p-bdc）2] （1）, was synthesized under hydrothermal conditions by a reaction of 1,3-bis（imidazol-l-ylmethyl）benzene （m-bix）, 1,3-benzene- dicarboxylic acid （H2p-bdc） and Zn（NO3）2. The colorless block crystals of complex 1 （C30H22N408Zn2） belong to the triclinic system, space group P1 with a = 10.213（2）, b = 12.052（2）, c = 12.392（3） A, a = 82.97（3）, β = 76.04（3）, y = 78.02（3）°, V= 1443.8（5） A3, Z = 2, Dc = 1.604 g/cm3, Mr = 697.26, F（000） = 708, R = 0.0403 and wR = 0.0907 for 4886 observed reflections （1 〉 2σ（I））. In 1, the tetrahedral Zn11 cations are linked by [p-bdc]2- anions into 2D sql networks, which are further connected by bix ligands forming an interesting 2-fold 4,4-connected mog-type 3D network with a point symbol of {4·6^4·8}^2{4^2·6^2·8^2}. Complex 1 was characterized by elemental, IR spectroscopy, powder X-ray diffractions and thermalgravimetric analysis. In addition, complex 1 exhibits coordination induced photoluminescent property.展开更多
Two three-dimensional lanthanide（Ⅲ） coordination polymers with the formula [Ln（PYDC）（NA）（H2O）]n [Ln=Gd（1）, Eu（2）, H2PYDC=pyridine-2,5-bicarboxylic acid, HNA=nicotinic acid] have been hydrothermally synthe...Two three-dimensional lanthanide（Ⅲ） coordination polymers with the formula [Ln（PYDC）（NA）（H2O）]n [Ln=Gd（1）, Eu（2）, H2PYDC=pyridine-2,5-bicarboxylic acid, HNA=nicotinic acid] have been hydrothermally synthesized and characterized by elemental analysis, IR, and single crystal X-ray diffraction. The NA came from in situ decarboxylation of the part of PYDC. X-ray single crystal structural analyses reveal that complexes 1 and 2 are isomorphous, they possess the 43.63 topology assembled by Gd^3＋/Eu^3＋ and two different multidentate carboxylate ligands Magnetic measurements show that antiferromagnetic coupling exists between adjacent Gd^3＋ ions in complex 1. The complex 2 exhibits the corresponding characteristic luminescence in the visible region under an excitation at 305 nm.展开更多
Three-dimensional(3D)urban structures play a critical role in informing climate mitigation strategies aimed at the built environment and facilitating sustainable urban development.Regrettably,there exists a significan...Three-dimensional(3D)urban structures play a critical role in informing climate mitigation strategies aimed at the built environment and facilitating sustainable urban development.Regrettably,there exists a significant gap in detailed and consistent data on 3D building space structures with global coverage due to the challenges inherent in the data collection and model calibration processes.In this study,we constructed a global urban structure(GUS-3D)dataset,including building volume,height,and footprint information,at a 500 m spatial resolution using extensive satellite observation products and numerous reference building samples.Our analysis indicated that the total volume of buildings worldwide in2015 exceeded 1×10^(12)m^(3).Over the 1985 to 2015 period,we observed a slight increase in the magnitude of 3D building volume growth(i.e.,it increased from 166.02 km3 during the 1985–2000 period to 175.08km3 during the 2000–2015 period),while the expansion magnitudes of the two-dimensional(2D)building footprint(22.51×10^(3) vs 13.29×10^(3)km^(2))and urban extent(157×10^(3) vs 133.8×10^(3)km^(2))notably decreased.This trend highlights the significant increase in intensive vertical utilization of urban land.Furthermore,we identified significant heterogeneity in building space provision and inequality across cities worldwide.This inequality is particularly pronounced in many populous Asian cities,which has been overlooked in previous studies on economic inequality.The GUS-3D dataset shows great potential to deepen our understanding of the urban environment and creates new horizons for numerous 3D urban studies.展开更多
This paper introduces a hybrid configuration design to enhance the precision of satellite antenna position measurement.By fixing the circular array antenna on the antenna mounting surface and integrating coordinate sy...This paper introduces a hybrid configuration design to enhance the precision of satellite antenna position measurement.By fixing the circular array antenna on the antenna mounting surface and integrating coordinate system transformation relationships with interferometric direction finding(DF)and positioning technology,accurate estimation of the antenna position is ensured.This method optimizes the quality and stability of data fusion by integrating pulse parameter characteristics,satellite orbit and attitude information,as well as the field of view information from observation stations,using techniques such as maximum-ratio-combining(MRC)and orbit extrapolation.Specifically,the sampling-importance resampling particle-filtering and Kalman-filtering(SIR-PF-KF)hybrid filtering prediction technology is employed to precisely predict and correct the three-dimensional(3D)position errors of the L-array antenna.Through data processing of five to nine orbits,accurate estimation of the antenna’s 3D position is achieved,achieving an estimation accuracy of 3μm,significantly improving the accuracy of on-orbit rapid calibration.Experimental results show that the interferometer positioning accuracy is improved from 7.9 km before antenna position correction to within 0.2 km after correction,verifying the effectiveness and practicability of this method,which aims to address issues with positioning accuracy.展开更多
To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D lea...To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D leader-following cooperative interception guidance law.First,in the LOS direction of the leader,an impact time-controlled guidance law is derived based on the fixed-time stability theory,which enables the leader to complete the interception task at a prespecified impact time.Next,in the LOS direction of the followers,by introducing a time consensus tracking error function,a fixed-time consensus tracking guidance law is investigated to guarantee the consensus tracking convergence of the time-to-go.Then,in the direction normal to the LOS,by combining the designed global integral sliding mode surface and the second-order Sliding Mode Control(SMC)theory,an innovative 3D LOS-angle-constrained interception guidance law is developed,which eliminates the reaching phase in the traditional sliding mode guidance laws and effectively saves energy consumption.Moreover,it effectively suppresses the chattering phenomenon while avoiding the singularity issue,and compensates for unknown interference caused by target maneuvering online,making it convenient for practical engineering applications.Finally,theoretical proof analysis and multiple sets of numerical simulation results verify the effectiveness,superiority,and robustness of the investigated guidance law.展开更多
A three-dimensional coordination polymer,[Ni（Hbyip2-）（bix）0.5（H2O）]n,has been hydrothermally synthesized.Each Ni2＋ ion is five-coordinated by three carboxylate O atoms from three different 5-（benzoic acid-4-yl...A three-dimensional coordination polymer,[Ni（Hbyip2-）（bix）0.5（H2O）]n,has been hydrothermally synthesized.Each Ni2＋ ion is five-coordinated by three carboxylate O atoms from three different 5-（benzoic acid-4-yldiazenyl）isophthalate（Hbyip2-） anions,one N atom from one 1,4-bis（imidazol-1-ylmethyl）benzene（bix） ligand and one O atom from an aqua ligand displaying a distorted square-pyramid.Each Ni atom is defined by three Hbyip2-anions and each Hbyip2-anion adopts a tris（mono-dentate） ligand coordinating to three Ni2＋ ions affording a 36-membered inorganic ring.These rings are further arranged into an undulated two-dimensional layer parallel to the（101） plane.Adjacent two-dimensional networks are linked by bix ligands into a three-dimensional {63,83}{63} framework with a large channel（ca.26.3 × 13.6） along the [100] direction.Each individual {63,83}{63} network interpenetrates with two others in a parallel fashion to generate a 3-fold interpenetrating network.展开更多
As the development of new power systems accelerates and the impacts of high renewable energy integration and extreme weather intensify,grid-alternative energy storage is garnering increasing attention for its grid-int...As the development of new power systems accelerates and the impacts of high renewable energy integration and extreme weather intensify,grid-alternative energy storage is garnering increasing attention for its grid-interaction benefits and clear business models.Consequently,assessing the value of grid-alternative energy storage in the systemtransition has become critically important.Considering the performance characteristics of storage,we propose a value assessment frame-work for grid-alternative energy storage,quantifying its non-wires-alternative effects from both cost and benefit perspectives.Building on this,we developed a collaborative planning model for energy storage and transmission grids,aimed at maximizing the economic benefits of storage systems while balancing investment and operational costs.The model considers regional grid interconnections and their interactions with system operation.By participating in system operations,grid-alternative energy storage not only maximizes its own economic benefits but also generates social welfare transfer effects.Furthermore,based on multi-regional interconnected planning,grid-alternative energy storage can reduce system costs by approximately 35%,with the most significant changes observed in generation costs.Multi-regional coordinated planning significantly enhances the sys-tem’s flexibility in regulation.However,when the load factor of interconnection lines between regions remains constant,system operational flexibility tends to decrease,leading to a roughly 28.9%increase in storage investment.Additionally,under regional coordinated planning,the greater the disparity in wind power integration across interconnected regions,the more noticeable the reduction in system costs.展开更多
A new 3D copper（Ⅱ） coordination polymer, {[Cu_2（tbip）_2（1,3,5-tib）]×2H_2O}n（1, H_2 tbip = 5-tert-butyl isophthalic acid, 1,3,5-tib = 1,3,5-tris（1-imidazolyl）benzene）, has been synthesized by hydrotherm...A new 3D copper（Ⅱ） coordination polymer, {[Cu_2（tbip）_2（1,3,5-tib）]×2H_2O}n（1, H_2 tbip = 5-tert-butyl isophthalic acid, 1,3,5-tib = 1,3,5-tris（1-imidazolyl）benzene）, has been synthesized by hydrothermal reaction of Cu（OAc）_2·4H_2O, H_2 tbip and 1,3,5-tib. It has been structurally characterized by element analysis, IR and magnetic measurement. X-ray single-crystal analysis was carried out for 1, which crystallizes in the triclinic system, space group P1 with a = 7.822（3）, b = 15.854（6）, c = 17.553（6） ？, a = 113.033（4）, β = 90.694（4）, g = 101.006（4）°, V = 1957.3（12） ？~3, Z = 1, D_c = 1.493 g/cm^3, M_r = 1759.70, F（000） = 908, R = 0.0721 and w R = 0.1978 with I 〉 2s（I）. The single-crystal X-ray diffraction studies reveal that compound 1 exhibits 2D [Cu（tbip）] layers which are further pillared by 1,3,5-tib ancillary ligand with terminal tridentate coordination mode to generate the final 3D structure. Magnetic susceptibility data for 1 have been measured in the range of 2~300 K. There are antiferromagnetic interactions between copper ions of the compound.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 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)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 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.
基金Support by the National Natural Science Foundation of China(21371052)
文摘A new coordination polymer, [Zn2（m-bix）（p-bdc）2] （1）, was synthesized under hydrothermal conditions by a reaction of 1,3-bis（imidazol-l-ylmethyl）benzene （m-bix）, 1,3-benzene- dicarboxylic acid （H2p-bdc） and Zn（NO3）2. The colorless block crystals of complex 1 （C30H22N408Zn2） belong to the triclinic system, space group P1 with a = 10.213（2）, b = 12.052（2）, c = 12.392（3） A, a = 82.97（3）, β = 76.04（3）, y = 78.02（3）°, V= 1443.8（5） A3, Z = 2, Dc = 1.604 g/cm3, Mr = 697.26, F（000） = 708, R = 0.0403 and wR = 0.0907 for 4886 observed reflections （1 〉 2σ（I））. In 1, the tetrahedral Zn11 cations are linked by [p-bdc]2- anions into 2D sql networks, which are further connected by bix ligands forming an interesting 2-fold 4,4-connected mog-type 3D network with a point symbol of {4·6^4·8}^2{4^2·6^2·8^2}. Complex 1 was characterized by elemental, IR spectroscopy, powder X-ray diffractions and thermalgravimetric analysis. In addition, complex 1 exhibits coordination induced photoluminescent property.
基金Supported by the Education Department Science Foundation of Liaoning Province(No.2008581)the Doctor Foundation of Liaoning Province(No.20071016)+1 种基金SRF for ROCS,SEM(No.200908)Liaoning BaiQian Wan Talents Program
文摘Two three-dimensional lanthanide（Ⅲ） coordination polymers with the formula [Ln（PYDC）（NA）（H2O）]n [Ln=Gd（1）, Eu（2）, H2PYDC=pyridine-2,5-bicarboxylic acid, HNA=nicotinic acid] have been hydrothermally synthesized and characterized by elemental analysis, IR, and single crystal X-ray diffraction. The NA came from in situ decarboxylation of the part of PYDC. X-ray single crystal structural analyses reveal that complexes 1 and 2 are isomorphous, they possess the 43.63 topology assembled by Gd^3＋/Eu^3＋ and two different multidentate carboxylate ligands Magnetic measurements show that antiferromagnetic coupling exists between adjacent Gd^3＋ ions in complex 1. The complex 2 exhibits the corresponding characteristic luminescence in the visible region under an excitation at 305 nm.
基金supported by the National Science Fund for Distinguished Young Scholars(42225107)the National Natural Science Foundation of China(42001326,42371414,42171409,and 42271419)+1 种基金the Natural Science Foundation of Guangdong Province of China(2022A1515012207)the Basic and Applied Basic Research Project of Guangzhou Science and Technology Planning(202201011539)。
文摘Three-dimensional(3D)urban structures play a critical role in informing climate mitigation strategies aimed at the built environment and facilitating sustainable urban development.Regrettably,there exists a significant gap in detailed and consistent data on 3D building space structures with global coverage due to the challenges inherent in the data collection and model calibration processes.In this study,we constructed a global urban structure(GUS-3D)dataset,including building volume,height,and footprint information,at a 500 m spatial resolution using extensive satellite observation products and numerous reference building samples.Our analysis indicated that the total volume of buildings worldwide in2015 exceeded 1×10^(12)m^(3).Over the 1985 to 2015 period,we observed a slight increase in the magnitude of 3D building volume growth(i.e.,it increased from 166.02 km3 during the 1985–2000 period to 175.08km3 during the 2000–2015 period),while the expansion magnitudes of the two-dimensional(2D)building footprint(22.51×10^(3) vs 13.29×10^(3)km^(2))and urban extent(157×10^(3) vs 133.8×10^(3)km^(2))notably decreased.This trend highlights the significant increase in intensive vertical utilization of urban land.Furthermore,we identified significant heterogeneity in building space provision and inequality across cities worldwide.This inequality is particularly pronounced in many populous Asian cities,which has been overlooked in previous studies on economic inequality.The GUS-3D dataset shows great potential to deepen our understanding of the urban environment and creates new horizons for numerous 3D urban studies.
文摘This paper introduces a hybrid configuration design to enhance the precision of satellite antenna position measurement.By fixing the circular array antenna on the antenna mounting surface and integrating coordinate system transformation relationships with interferometric direction finding(DF)and positioning technology,accurate estimation of the antenna position is ensured.This method optimizes the quality and stability of data fusion by integrating pulse parameter characteristics,satellite orbit and attitude information,as well as the field of view information from observation stations,using techniques such as maximum-ratio-combining(MRC)and orbit extrapolation.Specifically,the sampling-importance resampling particle-filtering and Kalman-filtering(SIR-PF-KF)hybrid filtering prediction technology is employed to precisely predict and correct the three-dimensional(3D)position errors of the L-array antenna.Through data processing of five to nine orbits,accurate estimation of the antenna’s 3D position is achieved,achieving an estimation accuracy of 3μm,significantly improving the accuracy of on-orbit rapid calibration.Experimental results show that the interferometer positioning accuracy is improved from 7.9 km before antenna position correction to within 0.2 km after correction,verifying the effectiveness and practicability of this method,which aims to address issues with positioning accuracy.
文摘To address the problem of multi-missile cooperative interception against maneuvering targets at a prespecified impact time and desired Line-of-Sight(LOS)angles in ThreeDimensional(3D)space,this paper proposes a 3D leader-following cooperative interception guidance law.First,in the LOS direction of the leader,an impact time-controlled guidance law is derived based on the fixed-time stability theory,which enables the leader to complete the interception task at a prespecified impact time.Next,in the LOS direction of the followers,by introducing a time consensus tracking error function,a fixed-time consensus tracking guidance law is investigated to guarantee the consensus tracking convergence of the time-to-go.Then,in the direction normal to the LOS,by combining the designed global integral sliding mode surface and the second-order Sliding Mode Control(SMC)theory,an innovative 3D LOS-angle-constrained interception guidance law is developed,which eliminates the reaching phase in the traditional sliding mode guidance laws and effectively saves energy consumption.Moreover,it effectively suppresses the chattering phenomenon while avoiding the singularity issue,and compensates for unknown interference caused by target maneuvering online,making it convenient for practical engineering applications.Finally,theoretical proof analysis and multiple sets of numerical simulation results verify the effectiveness,superiority,and robustness of the investigated guidance law.
基金Supported by the Natural Science Foundation of Henan Province(No.092300410119 and 102300410093)
文摘A three-dimensional coordination polymer,[Ni（Hbyip2-）（bix）0.5（H2O）]n,has been hydrothermally synthesized.Each Ni2＋ ion is five-coordinated by three carboxylate O atoms from three different 5-（benzoic acid-4-yldiazenyl）isophthalate（Hbyip2-） anions,one N atom from one 1,4-bis（imidazol-1-ylmethyl）benzene（bix） ligand and one O atom from an aqua ligand displaying a distorted square-pyramid.Each Ni atom is defined by three Hbyip2-anions and each Hbyip2-anion adopts a tris（mono-dentate） ligand coordinating to three Ni2＋ ions affording a 36-membered inorganic ring.These rings are further arranged into an undulated two-dimensional layer parallel to the（101） plane.Adjacent two-dimensional networks are linked by bix ligands into a three-dimensional {63,83}{63} framework with a large channel（ca.26.3 × 13.6） along the [100] direction.Each individual {63,83}{63} network interpenetrates with two others in a parallel fashion to generate a 3-fold interpenetrating network.
基金funded by the Technology Project of State Grid Jibei Electric Power Supply Co.,Ltd.(Grant Number:52018F240001).
文摘As the development of new power systems accelerates and the impacts of high renewable energy integration and extreme weather intensify,grid-alternative energy storage is garnering increasing attention for its grid-interaction benefits and clear business models.Consequently,assessing the value of grid-alternative energy storage in the systemtransition has become critically important.Considering the performance characteristics of storage,we propose a value assessment frame-work for grid-alternative energy storage,quantifying its non-wires-alternative effects from both cost and benefit perspectives.Building on this,we developed a collaborative planning model for energy storage and transmission grids,aimed at maximizing the economic benefits of storage systems while balancing investment and operational costs.The model considers regional grid interconnections and their interactions with system operation.By participating in system operations,grid-alternative energy storage not only maximizes its own economic benefits but also generates social welfare transfer effects.Furthermore,based on multi-regional interconnected planning,grid-alternative energy storage can reduce system costs by approximately 35%,with the most significant changes observed in generation costs.Multi-regional coordinated planning significantly enhances the sys-tem’s flexibility in regulation.However,when the load factor of interconnection lines between regions remains constant,system operational flexibility tends to decrease,leading to a roughly 28.9%increase in storage investment.Additionally,under regional coordinated planning,the greater the disparity in wind power integration across interconnected regions,the more noticeable the reduction in system costs.
基金supported by the National Natural Science Foundation of China(Nos.21271098 and 21371089)Science and Technology Research Key Project of the Education Department of Henan Province(No.14B150034)
文摘A new 3D copper（Ⅱ） coordination polymer, {[Cu_2（tbip）_2（1,3,5-tib）]×2H_2O}n（1, H_2 tbip = 5-tert-butyl isophthalic acid, 1,3,5-tib = 1,3,5-tris（1-imidazolyl）benzene）, has been synthesized by hydrothermal reaction of Cu（OAc）_2·4H_2O, H_2 tbip and 1,3,5-tib. It has been structurally characterized by element analysis, IR and magnetic measurement. X-ray single-crystal analysis was carried out for 1, which crystallizes in the triclinic system, space group P1 with a = 7.822（3）, b = 15.854（6）, c = 17.553（6） ？, a = 113.033（4）, β = 90.694（4）, g = 101.006（4）°, V = 1957.3（12） ？~3, Z = 1, D_c = 1.493 g/cm^3, M_r = 1759.70, F（000） = 908, R = 0.0721 and w R = 0.1978 with I 〉 2s（I）. The single-crystal X-ray diffraction studies reveal that compound 1 exhibits 2D [Cu（tbip）] layers which are further pillared by 1,3,5-tib ancillary ligand with terminal tridentate coordination mode to generate the final 3D structure. Magnetic susceptibility data for 1 have been measured in the range of 2~300 K. There are antiferromagnetic interactions between copper ions of the compound.
