With the rapid development of large-scale offshore wind farms,efficient and reliable power transmission systems are urgently needed.Hybrid high-voltage direct current(HVDC)configurations combining a diode rectifier un...With the rapid development of large-scale offshore wind farms,efficient and reliable power transmission systems are urgently needed.Hybrid high-voltage direct current(HVDC)configurations combining a diode rectifier unit(DRU)and a modular multilevel converter(MMC)have emerged as a promising solution,offering advantages in cost-effectiveness and control capability.However,the uncontrollable nature of the DRU poses significant challenges for systemstability under offshore AC fault conditions,particularly due to its inability to provide fault current or voltage support.This paper investigates the offshore AC fault characteristics and fault ride-through(FRT)strategy of a hybrid offshore wind power transmission system based on a diode rectifier unit DRU and MMC.First,the dynamic response of the hybrid system under offshore symmetrical three-phase faults is analyzed.It is demonstrated that due to the unidirectional conduction nature of the DRU,its AC current rapidly drops to zero during faults,and the fault current is solely contributed by the wind turbine generators(WTGs)and wind farm MMC(WFMMC).Based on this analysis,a coordinated FRT strategy is proposed,which combines a segmented current limiting control for the wind-turbine(WT)grid-side converters(GSCs)and a constant AC current control for the WFMMC.The strategy ensures effective voltage support during the fault and prevents MMC current saturation during fault recovery,enabling fast and stable system restoration.Electromagnetic transient simulations in PSCAD/EMTDC verify the feasibility of the proposed fault ride-through strategy.展开更多
During aircraft ground steering,the nose landing gear(NLG)tires of large transport aircraft often experience excessive lateral loads,leading to sideslip.This compromises steering safety and accelerates tire wear.To ad...During aircraft ground steering,the nose landing gear(NLG)tires of large transport aircraft often experience excessive lateral loads,leading to sideslip.This compromises steering safety and accelerates tire wear.To address this issue,the rear landing gear is typically designed to steer in coordination with the nose wheels,reducing sideslip and improving maneuverability.This study examines how structural parameters and weight distribution affect the performance of coordinated steering in landing gear design for large transport aircraft.Using the C-5 transport aircraft as a case study,we develop a multi-wheel ground steering dynamics model,incorporating the main landing gear(MLG)deflection.A ground handling dynamics model is also established to evaluate the benefits of coordinated steering for rear MLG during steering.Additionally,the study analyzes the impact of structural parameters such as stiffness and damping on the steering performance of the C-5.It further investigates the effects of weight distribution,including the center-of-gravity(CG)height,the longitudinal CG position,and the mass asymmetry.Results show that when the C-5 employs coordinated steering for rear MLG,the lateral friction coefficients of the NLG tires decrease by 22%,24%,26%,and 27%.The steering radius is reduced by 29.7%,and the NLG steering moment decreases by 19%,significantly enhancing maneuverability.Therefore,in the design of landing gear for large transport aircraft,coordinated MLG steering,along with optimal structural and CG position parameters,should be primary design objectives.These results provide theoretical guidance for the design of multi-wheel landing gear systems in large transport aircraft.展开更多
One of the greatest challenges in the agroecosystem is to improve cropland intensification while preserving agroecosystem services.While many studies have investigated the effect of cropland intensification on agroeco...One of the greatest challenges in the agroecosystem is to improve cropland intensification while preserving agroecosystem services.While many studies have investigated the effect of cropland intensification on agroecosystem service,the interactive coupling and coordination among these factors remain largely unexplored.In view of this,this study performed a case study of the Loess Plateau in Shaanxi Province,China and constructed comprehensive evaluation models to quantify the cropland intensification and agroecosystem service in this area.Balance analysis and the coupling coordination degree model were used to evaluate the interactive relationship between cropland intensification and agroecosystem service,and statistical analysis and spatial autocorrelation were used to analyze the spatial characteristics and potential mechanism of the coupling coordination.Results show that both the cropland intensification and agroecosystem service in the study area were relatively low yet gradually increased from 2000 to 2020.Agroecosystem service lag was identified as the dominant unbalanced development type.Improving the supply capacity of agroecosystem services plays a key role in the balanced development of cropland in the Loess Plateau.The coupling coordination degree between cropland intensification and agroecosystem service ranges from basic coordination to serious incoordination.Therefore,cropland intensification practices in the area should be optimized to enhance this coordination degree.An upward trend was also observed in the coupling coordination degree from2000 to 2020.The withdrawal of marginal cropland in the Grain for Green program is one of the most important reasons for this trend,especially for the northern region.Around 83.6%of the high-high clusters are concentrated in the southern region of the Loess Plateau,whereas 70.5%of the low-low clusters are distributed in the northern region.These clustering characteristics are mainly attributed to the environmental suitability of these areas for agriculture and their degree of economic development.展开更多
The safety impact of changes to roadway operations have been of interests in recent years with the publication of the Highway Safety Manual.One area that is in need of further study is the safety impact of traffic sig...The safety impact of changes to roadway operations have been of interests in recent years with the publication of the Highway Safety Manual.One area that is in need of further study is the safety impact of traffic signal coordination projects in urban areas.Specifically,this study seeks to identify the safety benefit from traffic signal coordination projects on major arterial roadways through urban areas using a before and after study with a comparison groups approach and a meta-analysis method.The findings suggest that traffic signal coordination could decrease total crashes by 21 percent,injury crashes by 52 percent and property-damage-only crashes by 21 percent.The results can be utilized by engineering practitioners to estimate the safety benefits for projects that seek to coordinate traffic signals along an urban corridor.Because these projects can both improve the safety of roadways while improving traffic flow,the application of these findings could be broad.展开更多
[Objective] The aim was to explore the measurement of coordinate parameter by multi-baseline digital close-range photogrammetry system.[Method] The 3-dimensional coordinate of 8-year-old Jujube was measured by using L...[Objective] The aim was to explore the measurement of coordinate parameter by multi-baseline digital close-range photogrammetry system.[Method] The 3-dimensional coordinate of 8-year-old Jujube was measured by using Lensphoto multi-baseline digital close-range photogrammetry system,and through comparing with measured data of Total Station,the error and accuracy of photogrammetry data were analyzed.[Result] The absolute error of X,Y and Z coordinate was 0-0.014,0-0.018 and 0-0.004 m respectively,and the relative error of X,Y and Z coordinate was less than 0.145%.The significance test of pairs for the photogrammetry data and measured data of Total Station indicated that the space coordinate data of stumpage were accurately measured by using the multi-baseline digital close-range photogrammetry method,and the photogrammetry data meet the need of space coordinate measurement for virtual plant growth simulation.[Conclusion] This study had provided theoretical basis for the growth measurement of virtual plant growth simulation.展开更多
The classical natural coordinate modeling method which removes the Euler angles and Euler parameters from the governing equations is particularly suitable for the sensitivity analysis and optimization of multibody sys...The classical natural coordinate modeling method which removes the Euler angles and Euler parameters from the governing equations is particularly suitable for the sensitivity analysis and optimization of multibody systems. However, the formulation has so many principles in choosing the generalized coordinates that it hinders the implementation of modeling automation, A first order direct sensitivity analysis approach to multibody systems formulated with novel natural coordinates is presented. Firstly, a new selection method for natural coordinate is developed. The method introduces 12 coordinates to describe the position and orientation of a spatial object. On the basis of the proposed natural coordinates, rigid constraint conditions, the basic constraint elements as well as the initial conditions for the governing equations are derived. Considering the characteristics of the governing equations, the newly proposed generalized-ct integration method is used and the corresponding algorithm flowchart is discussed. The objective function, the detailed analysis process of first order direct sensitivity analysis and related solving strategy are provided based on the previous modeling system Finally, in order to verify the validity and accuracy of the method presented, the sensitivity analysis of a planar spinner-slider mechanism and a spatial crank-slider mechanism are conducted. The test results agree well with that of the finite difference method, and the maximum absolute deviation of the results is less than 3%. The proposed approach is not only convenient for automatic modeling, but also helpful for the reduction of the complexity of sensitivity analysis, which provides a practical and effective way to obtain sensitivity for the optimization problems of multibody systems.展开更多
Walking is a complex task which includes hundreds of muscles, bones and joints working together to deliver smooth movements. With the complexity, walking has been widely investigated in order to identify the pattern o...Walking is a complex task which includes hundreds of muscles, bones and joints working together to deliver smooth movements. With the complexity, walking has been widely investigated in order to identify the pattern of multi-segment movement and reveal the control mechanism. The degree of freedom and dimensional properties provide a view of the coordinative structure during walking, which has been extensively studied by using dimension reduction technique. In this paper, the studies related to the coordinative structure, dimensions detection and pattern reorganization during walking have been reviewed. Principal component analysis, as a popular technique, is widely used in the processing of human movement data. Both the principle and the outcomes of principal component analysis were introduced in this paper. This technique has been reported to successfully reduce the redundancy within the original data, identify the physical meaning represented by the extracted principal components and discriminate the different patterns. The coordinative structure during walking assessed by this technique could provide further information of the body control mechanism and correlate walking pattern with injury.展开更多
Based on Kirchhoff plate theory and the Rayleigh-Ritz method,the model for free vibration of rectangular plate with rectangular cutouts under arbitrary elastic boundary conditions is established by using the improved ...Based on Kirchhoff plate theory and the Rayleigh-Ritz method,the model for free vibration of rectangular plate with rectangular cutouts under arbitrary elastic boundary conditions is established by using the improved Fourier series in combination with the independent coordinate coupling method(ICCM).The effect of the cutout is taken into account by subtracting the energies of the cutouts from the total energies of the whole plate.The vibration displacement function of the hole domain is based on the coordinate system of the hole domain in this method.From the continuity condition of the vibration displacement function at the cutout,the transition matrix between the two coordinate systems is constructed,and the mass and stiffness matrices are completely obtained.As a result,the calculation is simplified and the computational efficiency of the solution is improved.In this paper,numerical examples and modal experiments are presented to validate the effectiveness of the modeling methods,and parameters related to influencing factors of the rectangular plate are analyzed to study the vibration characteristics.展开更多
Background:Changes in lower limb joint coordination have been shown to increase localized stress on knee joint soft tissue—a known precursor of osteoarthritis.While 50%of individuals who undergo anterior cruciate lig...Background:Changes in lower limb joint coordination have been shown to increase localized stress on knee joint soft tissue—a known precursor of osteoarthritis.While 50%of individuals who undergo anterior cruciate ligament reconstruction(ACLR)develop radiographic osteoarthritis,it is unclear how underlying joint coordination during gait changes post-ACLR.The purpose of this study was twofold:to determine differences in lower limb coordination patterns during gait in ACLR individuals 2,4,and 6 months post-ACLR and to compare the coordination profiles of the ACLR participants at each timepoint post-ACLR to uninjured matched controls.Methods:We conducted a longitudinal assessment to quantify lower limb coordination at 3 timepoints post-ACLR and compared the ACLR coordination profiles to uninjured controls.Thirty-four ACLR(age=21.43±4.24 years,mean±SD;70.59%female)and 34 controls(age=21.42±3.43 years;70.59%female)participated.The ACLR group completed 3 overground gait assessments(2,4,and 6 months post-ACLR),and the controls completed one assessment,at which lower limb kinematics were collected.Cross-recurrence quantification analysis was used to characterize sagittal and frontal plane ankle-knee,ankle-hip,and knee-hip coordination dynamics.Comprehensive general linear mixed models were constructed to compare between-limb and within-limb coordination outcomes over time post-ACLR and a between-group comparison across timepoints.Results:The ACLR limb demonstrated a more"stuck"sagittal plane knee-hip coordination profile(greater trapping time(TT);p=0.004)compared bilaterally.Between groups,the ACLR participants exhibited a more predictable ankle-knee coordination pattern(percent determinism(%DET);p<0.05),stronger coupling between joints(meanline(MNLine))across all segments(p<0.05),and greater knee-hip TT(more"stuck";p<0.05)compared to the controls at each timepoint in the sagittal plane.Stronger frontal plane knee-hip joint coupling(MNLine)persisted across timepoints within the ACLR group compared to the controls(p<0.05).Conclusion:The results indicate ACLR individuals exhibit a distinct and rigid coordination pattern during gait compared to controls within6-month post-ACLR,which may have long-term implications for knee-joint health.展开更多
In this paper,the Taixin Integrated Economic Zone in Shanxi Province is taken as the research object,and the coupling coordination degree model and bivariate spatial autocorrelation model are used to judge the couplin...In this paper,the Taixin Integrated Economic Zone in Shanxi Province is taken as the research object,and the coupling coordination degree model and bivariate spatial autocorrelation model are used to judge the coupling coordination and spatial-temporal correlation between urbanization and ecosystem service,and the hotspot analysis is used to judge the spatial-temporal trend of urbanization and ecosystem service.The results show that:(1)The urbanization level from 2000 to 2020 continued to rise,the areas with relatively high urbanization were concentrated in the central part of the study area,and the relatively high terrain areas on both sides of the study area,the urbanization was relatively slow,and the hotspot areas with highly significant and significant urbanization level from 2000 to 2020 were distributed as bands in the central part of the study area and the area was rising,and there was no Cold spot area distribution;between 2000 and 2020,the ecosystem service value in the study area increased by 2.6800×10^(8) yuan.Over these two decades,it exhibited a development trend that first rose and then declined.The woodland and grassland agglomeration areas were located on the two sides of the study area,forming highly significant and significant hotspots.Conversely,the central and northeastern parts of the study area were characterized by concentrated man-made land surfaces and croplands,resulting in the formation of highly significant and significant cold spots.(2)In the central part of the study area where man-made land surface and cultivated land are concentrated,the coupling coordination between urbanization and ecosystem service is in the intermediate dislocation and mild dislocation interval;the woodland and grassland concentration areas on both sides of the study area are ecologically fragile,and the coupling coordination between the two is in the level of less than intermediate dislocation.(3)From 2000 to 2020,urbanization and the value of ecosystem services were both negatively correlated,although the correlation coefficient was low.In the central and northeastern parts,urbanization and ecosystem service exhibited patterns of high-low,high-high,and low-low clustering.Conversely,on both sides of the study area,most of the clusters showed a low-high pattern.展开更多
A new approach based on stereo vision technology is introduced to analyzesheet metal deformation. By measuring the deformed circle grids that are printed on the sheetsurface before forming, the strain distribution of ...A new approach based on stereo vision technology is introduced to analyzesheet metal deformation. By measuring the deformed circle grids that are printed on the sheetsurface before forming, the strain distribution of the workpiece is obtained. The measurement andanalysis results can be used to verify numerical simulation results and guide production. To getgood accuracy, some new techniques are employed: camera calibration based on genetic algorithm,feature abstraction based on self-adaptive technology, image matching based on structure feature andcamera modeling pre-constrains, and parameter calculation based on curve and surface optimization.The experimental values show that the approach proposed is rational and practical, which can providebetter measurement accuracy with less time than the conventional method.展开更多
The Hamiltonian analysis for a 3-dimensional connection dynamics of o（1, 2）, spanned by {L-＋, L-2, L＋2） instead of {Lol, L02, L12}, is first conducted in a Bondi-like coordinate system. The symmetry of the system...The Hamiltonian analysis for a 3-dimensional connection dynamics of o（1, 2）, spanned by {L-＋, L-2, L＋2） instead of {Lol, L02, L12}, is first conducted in a Bondi-like coordinate system. The symmetry of the system is clearly presented. A null coframe with 3 independent variables and 9 connection coefficients are treated as basic configuration variables. All constraints and their consistency conditions, the solutions of Lagrange multipliers as well as the equations of motion are presented. There is no physical degree of freedom in the system. The Bafiados-Teitelboim-Zanelli （BTZ） spaeetime is discussed as an example to check the analysis. Unlike the ADM formalism, where only non-degenerate geometries on slices are dealt with and the Ashtekar formalism, where non-degenerate geometries on slices are mainly concerned though the degenerate geometries may be studied as well, in the present formalism the geometries on the slices are always degenerate though the geometries for the spacetime are not degenerate.展开更多
In China,the Innovation Demonstration Zone for the National Sustainable Development Agenda is a key initiative for executing the United Nations(UN)2030 Agenda for Sustainable Development.The Zone also plays critical r...In China,the Innovation Demonstration Zone for the National Sustainable Development Agenda is a key initiative for executing the United Nations(UN)2030 Agenda for Sustainable Development.The Zone also plays critical roles in addressing the developmental bottlenecks that China faces and sharing Chinese insights into global sustainable development efforts.On July 15,2022,the State Council endorsed the Zone’s establishment in Zaozhuang City,Shandong Province,where it focuses on innovation-led sustainable development in rural areas.Research into the levels,impediments,interdependencies,and evolutionary trends of rural sustainable development is crucial.Therefore,this research aimed to assist in comprehensively assessing developmental challenges and facilitating the harmonious advancement of social,economic,and environmental aspects in rural areas.In pursuit of the three fundamental dimensions of the UN’s Sustainable Development Goals(SDGs),namely development’s drivers,quality,and equity,this study was grounded in China’s national Rural Revitalization Strategy and the demands of sustainable development strategies.It also aligns with the UN 2030 Agenda for Sustainable Development and the associated SDG indicators.Focusing on four key areas,namely production elements,natural elements,social elements,and rural governance,this study developed an evaluation index system for assessing the level of rural sustainable development.It employed a range of analytical models,including the game theory-based combination empowerment method,barrier degree model,coupling degree model,coupling coordination degree model,and gray prediction GM(1,1)model,to analyze the status and evolving trends of rural sustainable development in Zaozhuang City from 2015 to 2022.The key findings were as follows:①Relative to the baseline year 2015,the sustainable development level in Zaozhuang’s rural areas has shifted toward an improved state overall.②The primary barrier to achieving rural sustainable development in Zaozhuang is the city’s rural governance system.③While the components of rural sustainable development in Zaozhuang are in the early stages of both basic and moderate coordination,an overall enhancement has occurred in their integrative coordination.④Between 2023 and 2025,the level of integrative coordination in Zaozhuang is expected to rise steadily.However,reaching a state of advanced coordination will require additional time for development.展开更多
Genetic diversity of 18 processing apple varieties and two fresh varieties were evaluated using 12 simple sequence repeats （SSR） primer pairs previously identified in Malus domestica Borkh. A total of 87 alleles in ...Genetic diversity of 18 processing apple varieties and two fresh varieties were evaluated using 12 simple sequence repeats （SSR） primer pairs previously identified in Malus domestica Borkh. A total of 87 alleles in 10 loci were detected using 10 polymorphic SSR markers selected within the range of 5-14 alleles per locus. All the 20 varieties could be distinguished using two primer pairs and they were divided into four groups using cluster analysis. The genetic similarity （GS） of groups analyzed using cluster analysis varied from 0.14 to 0.83. High acid variety Avrolles separated from other varieties with GS less than 0.42. The second group contained Longfeng and Dolgo from Northeast of China, the inherited genes of Chinese crab apple. The five cider varieties with high tannin contents, namely, Dabinette, Frequin rouge, Kermerrien, M.Menard, and D.Coetligne were clustered into the third group. The fourth group was mainly composed of 12 juice and fresh varieties. Principal coordinate analysis （PCO） also divided all the varieties into four groups. Juice and fresh apple varieties, Longfeng and Dolgo were clustered together, respectively, using both the analyses. Both the analyses showed there was much difference between cider and juice varieties, cider and fresh varieties, as well as Chinese crab apple and western European crab apple, whereas juice varieties and fresh varieties had a similar genetic background. The genetic diversity and differentiation could be sufficiently reflected by combining the two analytical methods.展开更多
A one-dimensional chain coordination polymer [Cu（phen）（2,4,6-TMBA）2（H2O）]n has been synthesized by reacting 2,4,6-trimethyl-benzoic acid, 1,10-phenanthroline and Cu（Ⅱ） perchlorate and its structure was charac...A one-dimensional chain coordination polymer [Cu（phen）（2,4,6-TMBA）2（H2O）]n has been synthesized by reacting 2,4,6-trimethyl-benzoic acid, 1,10-phenanthroline and Cu（Ⅱ） perchlorate and its structure was characterized. Crystal data for this complex： tetragonal, space group I41, a = 2.0293（3）, b = 2.0293（3）, c = 1.3758（2） nm, α =β= γ = 90°, V= 5.6657（13） nm3, Dc= 1.379 g/cm3, Z = 8, μ（MoKa） = 0.815 mm-1, Mr = 588.14, F（000） = 2456, S = 1.047, R = 0.0459 and wR = 0.1053. The crystal structure shows that two neighboring Cu（Ⅱ） ions are linked together by one bridging-chelating 2,4,6-trimethyl-benzoic group, forming a one-dimensional chain structure. Each Cu（Ⅱ） ion is coordinated with two nitrogen atoms from one 1,10-phenanthroline molecule, three oxygen atoms from three 2,4,6-trimethyl-benzoic acid molecules and one oxygen atom from one water molecule, giving a six-coordinate distorted octahedral coordination geometry. The cyclic voltammetry behavior of the complex was also investigated.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
During the rapid industrialization and urbanization of China,urban agglomeration in river basin areas raises the problems of over-use of water resources and pollution of the water environment.Related research in China...During the rapid industrialization and urbanization of China,urban agglomeration in river basin areas raises the problems of over-use of water resources and pollution of the water environment.Related research in China has mainly focused on the conflicts among economic growth,urban expansion and water resource shortages within admin-istrative boundaries.However,water environments are much more dependent on their physical boundaries than their administrative boundaries.Consistent with the nature of water environment,this study aims at analyzing coordination relationships between urban development and water environment changes within physical river basin boundaries.We chose the Shayinghe River Basin,China,as our case study area which is facing serious challenges related to water en-vironment protection.Then we classified 35 county-level administrative units into upstream,midstream and down-stream regions based on their physical characteristics;analyzed the coordination degree of urban agglomeration using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method;and constructed cooperative models using the Linear Programming (LP function) to simulate four scenarios of the coordination relationship be-tween urban population increase and water environment protection based on existing water resources and water pollu-tion data.The results show that the present coordinative situation in Shayinghe River Basin is not sustainable.In gen-eral,more than 50% administrative units are in the bad coordinative situation.In particular,the downstream region is under worse condition than the upstream and midstream regions.Cooperative models in scenario analyses indicate that the population scale set in existing urban master plannings is not coordinated with the water environment protection.To reach the goal of regional sustainable development,the total population needs to be controlled such that it will re-main at 4.5×10 7 or below by 2020 given the capacity of water environment.展开更多
One-dimensional chain copper（Ⅱ） coordination polymer has been synthesized and characterized in the solvent mixture of water and alcohol with o-acetamidobenzoic acid,4,4＇-bipyridine and copper perchlorate.It is of ...One-dimensional chain copper（Ⅱ） coordination polymer has been synthesized and characterized in the solvent mixture of water and alcohol with o-acetamidobenzoic acid,4,4＇-bipyridine and copper perchlorate.It is of tetragonal,space group P41212 with a=1.57756（10）,b= 1.57756（10）,c=2.1438（3）nm,V=5.3352（8） nm^3,Dc=1.524 g/cm^3,Z=4,F（000）=2536,R= 0.0479 and wR=0.0979.The crystal structure shows two coordination modes.The copper（1） is coordinated with two nitrogen atoms of one 4,4＇-bipyridine molecule and two oxygen atoms from two o-acetamidobenzoic acid molecules,forming a distorted tetrahedral coordination geometry; the copper（2） is coordinated with two nitrogen atoms of one 4,4＇-bipyridine molecule,four oxygen atoms from two o-acetamidobenzoic acid molecules and two water molecules,generating a distorted octahedral coordination geometry.The result of TG analysis shows that the title complex is stable below 180.0 ℃.展开更多
A novel one-dimensional chain coordination polymer [Mn（NAAh（4,4′-bipy）（H2O）4], has been synthesized with a-naphthaleneacetic acid, 4,4′-bipy and manganese（Ⅱ） sulfate as raw materials. Crystal data for this c...A novel one-dimensional chain coordination polymer [Mn（NAAh（4,4′-bipy）（H2O）4], has been synthesized with a-naphthaleneacetic acid, 4,4′-bipy and manganese（Ⅱ） sulfate as raw materials. Crystal data for this complex： monoclinic, space group P21/c, a = 1.1421（2）, b = 1.6337（3）, c = 0.94177（19） nm, β = 112.15（3）°, V = 1.6275（6） nm^3, De = 1.407 g/cm^3, Z = 2, μ（MoKa） = 0.467 mm^-1, F（000） = 722, S = 1.007, R= 0.0412 and wR = 0.1022. The crystal structure shows that two neighboring manganese（Ⅱ） ions are linked together by one 4,4′-bipy molecule, and the whole complex molecule forms a one-dimensional chain structure. Each manganese（Ⅱ） ion is coordinated with two oxygen atoms of two a-naphthaleneacetic acid molecules, two nitrogen atoms of two 4,4′-bipy molecules and two oxygen atoms from two water molecules, giving a distorted octahedral coordination geometry. The electrochemical properties were also analyzed.展开更多
BACKGROUND Gut microbiota is an emerging field of research,with related research having breakthrough development in the past 15 years.Bibliometric analysis can be applied to analyze the evolutionary trends and emergin...BACKGROUND Gut microbiota is an emerging field of research,with related research having breakthrough development in the past 15 years.Bibliometric analysis can be applied to analyze the evolutionary trends and emerging hotspots in this field.AIM To study the subject trends and knowledge structures of gut microbiota related research fields from 2004 to 2018.METHODS The literature data on gut microbiota were identified and downloaded from the PubMed database.Through biclustering analysis,strategic diagrams,and social network analysis diagrams,the main trend and knowledge structure of research fields concerning gut microbiota were analyzed to obtain and compare the research hotspots in each period.RESULTS According to the strategic coordinates and social relationship network map,Clostridium Infections/microbiology,Clostridium Infections/therapy,RNA,Ribosomal,16S/genetics,Microbiota/genetics,Microbiota/immunology,Dysbiosis/immunology,Infla-mmation/immunology,Fecal Microbiota Transplantation/methods,Fecal Microbiota Transplantation can be used as an emerging research hotspot in the past 5 years(2014-2018).CONCLUSION Some subjects were not yet fully studied according to the strategic coordinates;and the emerging hotspots in the social network map can be considered as directions of future research.展开更多
基金funded by the Science and Technology Projects of State Grid Zhejiang Electric Power Co.,Ltd.(5211DS24000G).
文摘With the rapid development of large-scale offshore wind farms,efficient and reliable power transmission systems are urgently needed.Hybrid high-voltage direct current(HVDC)configurations combining a diode rectifier unit(DRU)and a modular multilevel converter(MMC)have emerged as a promising solution,offering advantages in cost-effectiveness and control capability.However,the uncontrollable nature of the DRU poses significant challenges for systemstability under offshore AC fault conditions,particularly due to its inability to provide fault current or voltage support.This paper investigates the offshore AC fault characteristics and fault ride-through(FRT)strategy of a hybrid offshore wind power transmission system based on a diode rectifier unit DRU and MMC.First,the dynamic response of the hybrid system under offshore symmetrical three-phase faults is analyzed.It is demonstrated that due to the unidirectional conduction nature of the DRU,its AC current rapidly drops to zero during faults,and the fault current is solely contributed by the wind turbine generators(WTGs)and wind farm MMC(WFMMC).Based on this analysis,a coordinated FRT strategy is proposed,which combines a segmented current limiting control for the wind-turbine(WT)grid-side converters(GSCs)and a constant AC current control for the WFMMC.The strategy ensures effective voltage support during the fault and prevents MMC current saturation during fault recovery,enabling fast and stable system restoration.Electromagnetic transient simulations in PSCAD/EMTDC verify the feasibility of the proposed fault ride-through strategy.
基金supported in part by the Fundamental Research Funds for the Central Universi-ties(No.NP2022416)the Aeronautical Science Founda-tion of China(No.2022Z029052001).
文摘During aircraft ground steering,the nose landing gear(NLG)tires of large transport aircraft often experience excessive lateral loads,leading to sideslip.This compromises steering safety and accelerates tire wear.To address this issue,the rear landing gear is typically designed to steer in coordination with the nose wheels,reducing sideslip and improving maneuverability.This study examines how structural parameters and weight distribution affect the performance of coordinated steering in landing gear design for large transport aircraft.Using the C-5 transport aircraft as a case study,we develop a multi-wheel ground steering dynamics model,incorporating the main landing gear(MLG)deflection.A ground handling dynamics model is also established to evaluate the benefits of coordinated steering for rear MLG during steering.Additionally,the study analyzes the impact of structural parameters such as stiffness and damping on the steering performance of the C-5.It further investigates the effects of weight distribution,including the center-of-gravity(CG)height,the longitudinal CG position,and the mass asymmetry.Results show that when the C-5 employs coordinated steering for rear MLG,the lateral friction coefficients of the NLG tires decrease by 22%,24%,26%,and 27%.The steering radius is reduced by 29.7%,and the NLG steering moment decreases by 19%,significantly enhancing maneuverability.Therefore,in the design of landing gear for large transport aircraft,coordinated MLG steering,along with optimal structural and CG position parameters,should be primary design objectives.These results provide theoretical guidance for the design of multi-wheel landing gear systems in large transport aircraft.
基金Under the auspices of the National Natural Science Foundation of China(No.41901262)Natural Science Basic Research Program of Shaanxi(No.2024JC-YBQN-0300)Fundamental Research Funds for the Central Universities(No.GK202103125,GK202207005)。
文摘One of the greatest challenges in the agroecosystem is to improve cropland intensification while preserving agroecosystem services.While many studies have investigated the effect of cropland intensification on agroecosystem service,the interactive coupling and coordination among these factors remain largely unexplored.In view of this,this study performed a case study of the Loess Plateau in Shaanxi Province,China and constructed comprehensive evaluation models to quantify the cropland intensification and agroecosystem service in this area.Balance analysis and the coupling coordination degree model were used to evaluate the interactive relationship between cropland intensification and agroecosystem service,and statistical analysis and spatial autocorrelation were used to analyze the spatial characteristics and potential mechanism of the coupling coordination.Results show that both the cropland intensification and agroecosystem service in the study area were relatively low yet gradually increased from 2000 to 2020.Agroecosystem service lag was identified as the dominant unbalanced development type.Improving the supply capacity of agroecosystem services plays a key role in the balanced development of cropland in the Loess Plateau.The coupling coordination degree between cropland intensification and agroecosystem service ranges from basic coordination to serious incoordination.Therefore,cropland intensification practices in the area should be optimized to enhance this coordination degree.An upward trend was also observed in the coupling coordination degree from2000 to 2020.The withdrawal of marginal cropland in the Grain for Green program is one of the most important reasons for this trend,especially for the northern region.Around 83.6%of the high-high clusters are concentrated in the southern region of the Loess Plateau,whereas 70.5%of the low-low clusters are distributed in the northern region.These clustering characteristics are mainly attributed to the environmental suitability of these areas for agriculture and their degree of economic development.
文摘The safety impact of changes to roadway operations have been of interests in recent years with the publication of the Highway Safety Manual.One area that is in need of further study is the safety impact of traffic signal coordination projects in urban areas.Specifically,this study seeks to identify the safety benefit from traffic signal coordination projects on major arterial roadways through urban areas using a before and after study with a comparison groups approach and a meta-analysis method.The findings suggest that traffic signal coordination could decrease total crashes by 21 percent,injury crashes by 52 percent and property-damage-only crashes by 21 percent.The results can be utilized by engineering practitioners to estimate the safety benefits for projects that seek to coordinate traffic signals along an urban corridor.Because these projects can both improve the safety of roadways while improving traffic flow,the application of these findings could be broad.
基金Supported by National Natural Science Foundation of China(30770401)National Eleventh Five-Year Plan for Forestry Scienceand Technology Support Topics(2006BADO3A0505)~~
文摘[Objective] The aim was to explore the measurement of coordinate parameter by multi-baseline digital close-range photogrammetry system.[Method] The 3-dimensional coordinate of 8-year-old Jujube was measured by using Lensphoto multi-baseline digital close-range photogrammetry system,and through comparing with measured data of Total Station,the error and accuracy of photogrammetry data were analyzed.[Result] The absolute error of X,Y and Z coordinate was 0-0.014,0-0.018 and 0-0.004 m respectively,and the relative error of X,Y and Z coordinate was less than 0.145%.The significance test of pairs for the photogrammetry data and measured data of Total Station indicated that the space coordinate data of stumpage were accurately measured by using the multi-baseline digital close-range photogrammetry method,and the photogrammetry data meet the need of space coordinate measurement for virtual plant growth simulation.[Conclusion] This study had provided theoretical basis for the growth measurement of virtual plant growth simulation.
基金supported by National Defense Pre-research Foundation of China during the 12th Five-Year Plan Period(Grant No.51036050107)
文摘The classical natural coordinate modeling method which removes the Euler angles and Euler parameters from the governing equations is particularly suitable for the sensitivity analysis and optimization of multibody systems. However, the formulation has so many principles in choosing the generalized coordinates that it hinders the implementation of modeling automation, A first order direct sensitivity analysis approach to multibody systems formulated with novel natural coordinates is presented. Firstly, a new selection method for natural coordinate is developed. The method introduces 12 coordinates to describe the position and orientation of a spatial object. On the basis of the proposed natural coordinates, rigid constraint conditions, the basic constraint elements as well as the initial conditions for the governing equations are derived. Considering the characteristics of the governing equations, the newly proposed generalized-ct integration method is used and the corresponding algorithm flowchart is discussed. The objective function, the detailed analysis process of first order direct sensitivity analysis and related solving strategy are provided based on the previous modeling system Finally, in order to verify the validity and accuracy of the method presented, the sensitivity analysis of a planar spinner-slider mechanism and a spatial crank-slider mechanism are conducted. The test results agree well with that of the finite difference method, and the maximum absolute deviation of the results is less than 3%. The proposed approach is not only convenient for automatic modeling, but also helpful for the reduction of the complexity of sensitivity analysis, which provides a practical and effective way to obtain sensitivity for the optimization problems of multibody systems.
文摘Walking is a complex task which includes hundreds of muscles, bones and joints working together to deliver smooth movements. With the complexity, walking has been widely investigated in order to identify the pattern of multi-segment movement and reveal the control mechanism. The degree of freedom and dimensional properties provide a view of the coordinative structure during walking, which has been extensively studied by using dimension reduction technique. In this paper, the studies related to the coordinative structure, dimensions detection and pattern reorganization during walking have been reviewed. Principal component analysis, as a popular technique, is widely used in the processing of human movement data. Both the principle and the outcomes of principal component analysis were introduced in this paper. This technique has been reported to successfully reduce the redundancy within the original data, identify the physical meaning represented by the extracted principal components and discriminate the different patterns. The coordinative structure during walking assessed by this technique could provide further information of the body control mechanism and correlate walking pattern with injury.
基金support of this work by the National Natural Science Foundation of China(No.51405096)the Fundamental Research Funds for the Central Universities(HEUCF210710).
文摘Based on Kirchhoff plate theory and the Rayleigh-Ritz method,the model for free vibration of rectangular plate with rectangular cutouts under arbitrary elastic boundary conditions is established by using the improved Fourier series in combination with the independent coordinate coupling method(ICCM).The effect of the cutout is taken into account by subtracting the energies of the cutouts from the total energies of the whole plate.The vibration displacement function of the hole domain is based on the coordinate system of the hole domain in this method.From the continuity condition of the vibration displacement function at the cutout,the transition matrix between the two coordinate systems is constructed,and the mass and stiffness matrices are completely obtained.As a result,the calculation is simplified and the computational efficiency of the solution is improved.In this paper,numerical examples and modal experiments are presented to validate the effectiveness of the modeling methods,and parameters related to influencing factors of the rectangular plate are analyzed to study the vibration characteristics.
基金supported by the Arthritis Foundation(principal investigator:BP)the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health(P30-AR072580)。
文摘Background:Changes in lower limb joint coordination have been shown to increase localized stress on knee joint soft tissue—a known precursor of osteoarthritis.While 50%of individuals who undergo anterior cruciate ligament reconstruction(ACLR)develop radiographic osteoarthritis,it is unclear how underlying joint coordination during gait changes post-ACLR.The purpose of this study was twofold:to determine differences in lower limb coordination patterns during gait in ACLR individuals 2,4,and 6 months post-ACLR and to compare the coordination profiles of the ACLR participants at each timepoint post-ACLR to uninjured matched controls.Methods:We conducted a longitudinal assessment to quantify lower limb coordination at 3 timepoints post-ACLR and compared the ACLR coordination profiles to uninjured controls.Thirty-four ACLR(age=21.43±4.24 years,mean±SD;70.59%female)and 34 controls(age=21.42±3.43 years;70.59%female)participated.The ACLR group completed 3 overground gait assessments(2,4,and 6 months post-ACLR),and the controls completed one assessment,at which lower limb kinematics were collected.Cross-recurrence quantification analysis was used to characterize sagittal and frontal plane ankle-knee,ankle-hip,and knee-hip coordination dynamics.Comprehensive general linear mixed models were constructed to compare between-limb and within-limb coordination outcomes over time post-ACLR and a between-group comparison across timepoints.Results:The ACLR limb demonstrated a more"stuck"sagittal plane knee-hip coordination profile(greater trapping time(TT);p=0.004)compared bilaterally.Between groups,the ACLR participants exhibited a more predictable ankle-knee coordination pattern(percent determinism(%DET);p<0.05),stronger coupling between joints(meanline(MNLine))across all segments(p<0.05),and greater knee-hip TT(more"stuck";p<0.05)compared to the controls at each timepoint in the sagittal plane.Stronger frontal plane knee-hip joint coupling(MNLine)persisted across timepoints within the ACLR group compared to the controls(p<0.05).Conclusion:The results indicate ACLR individuals exhibit a distinct and rigid coordination pattern during gait compared to controls within6-month post-ACLR,which may have long-term implications for knee-joint health.
基金supported by the Natural Science Foundation of Shanxi Province(Grant No.20210302124437)the Graduate Student Research and Innovation Project of Shanxi Province(Grant No.2023KY551).
文摘In this paper,the Taixin Integrated Economic Zone in Shanxi Province is taken as the research object,and the coupling coordination degree model and bivariate spatial autocorrelation model are used to judge the coupling coordination and spatial-temporal correlation between urbanization and ecosystem service,and the hotspot analysis is used to judge the spatial-temporal trend of urbanization and ecosystem service.The results show that:(1)The urbanization level from 2000 to 2020 continued to rise,the areas with relatively high urbanization were concentrated in the central part of the study area,and the relatively high terrain areas on both sides of the study area,the urbanization was relatively slow,and the hotspot areas with highly significant and significant urbanization level from 2000 to 2020 were distributed as bands in the central part of the study area and the area was rising,and there was no Cold spot area distribution;between 2000 and 2020,the ecosystem service value in the study area increased by 2.6800×10^(8) yuan.Over these two decades,it exhibited a development trend that first rose and then declined.The woodland and grassland agglomeration areas were located on the two sides of the study area,forming highly significant and significant hotspots.Conversely,the central and northeastern parts of the study area were characterized by concentrated man-made land surfaces and croplands,resulting in the formation of highly significant and significant cold spots.(2)In the central part of the study area where man-made land surface and cultivated land are concentrated,the coupling coordination between urbanization and ecosystem service is in the intermediate dislocation and mild dislocation interval;the woodland and grassland concentration areas on both sides of the study area are ecologically fragile,and the coupling coordination between the two is in the level of less than intermediate dislocation.(3)From 2000 to 2020,urbanization and the value of ecosystem services were both negatively correlated,although the correlation coefficient was low.In the central and northeastern parts,urbanization and ecosystem service exhibited patterns of high-low,high-high,and low-low clustering.Conversely,on both sides of the study area,most of the clusters showed a low-high pattern.
文摘A new approach based on stereo vision technology is introduced to analyzesheet metal deformation. By measuring the deformed circle grids that are printed on the sheetsurface before forming, the strain distribution of the workpiece is obtained. The measurement andanalysis results can be used to verify numerical simulation results and guide production. To getgood accuracy, some new techniques are employed: camera calibration based on genetic algorithm,feature abstraction based on self-adaptive technology, image matching based on structure feature andcamera modeling pre-constrains, and parameter calculation based on curve and surface optimization.The experimental values show that the approach proposed is rational and practical, which can providebetter measurement accuracy with less time than the conventional method.
基金Supported by National Natural Science Foundation of China under Grant Nos.11275207 and 11690022
文摘The Hamiltonian analysis for a 3-dimensional connection dynamics of o（1, 2）, spanned by {L-＋, L-2, L＋2） instead of {Lol, L02, L12}, is first conducted in a Bondi-like coordinate system. The symmetry of the system is clearly presented. A null coframe with 3 independent variables and 9 connection coefficients are treated as basic configuration variables. All constraints and their consistency conditions, the solutions of Lagrange multipliers as well as the equations of motion are presented. There is no physical degree of freedom in the system. The Bafiados-Teitelboim-Zanelli （BTZ） spaeetime is discussed as an example to check the analysis. Unlike the ADM formalism, where only non-degenerate geometries on slices are dealt with and the Ashtekar formalism, where non-degenerate geometries on slices are mainly concerned though the degenerate geometries may be studied as well, in the present formalism the geometries on the slices are always degenerate though the geometries for the spacetime are not degenerate.
基金supported by the National Key Research and Development Plan[Grant No.2022YFC3802901-01],the Zaozhuang Independent Innovation and Achievement Transformation Plan[Grant No.2021GH21].
文摘In China,the Innovation Demonstration Zone for the National Sustainable Development Agenda is a key initiative for executing the United Nations(UN)2030 Agenda for Sustainable Development.The Zone also plays critical roles in addressing the developmental bottlenecks that China faces and sharing Chinese insights into global sustainable development efforts.On July 15,2022,the State Council endorsed the Zone’s establishment in Zaozhuang City,Shandong Province,where it focuses on innovation-led sustainable development in rural areas.Research into the levels,impediments,interdependencies,and evolutionary trends of rural sustainable development is crucial.Therefore,this research aimed to assist in comprehensively assessing developmental challenges and facilitating the harmonious advancement of social,economic,and environmental aspects in rural areas.In pursuit of the three fundamental dimensions of the UN’s Sustainable Development Goals(SDGs),namely development’s drivers,quality,and equity,this study was grounded in China’s national Rural Revitalization Strategy and the demands of sustainable development strategies.It also aligns with the UN 2030 Agenda for Sustainable Development and the associated SDG indicators.Focusing on four key areas,namely production elements,natural elements,social elements,and rural governance,this study developed an evaluation index system for assessing the level of rural sustainable development.It employed a range of analytical models,including the game theory-based combination empowerment method,barrier degree model,coupling degree model,coupling coordination degree model,and gray prediction GM(1,1)model,to analyze the status and evolving trends of rural sustainable development in Zaozhuang City from 2015 to 2022.The key findings were as follows:①Relative to the baseline year 2015,the sustainable development level in Zaozhuang’s rural areas has shifted toward an improved state overall.②The primary barrier to achieving rural sustainable development in Zaozhuang is the city’s rural governance system.③While the components of rural sustainable development in Zaozhuang are in the early stages of both basic and moderate coordination,an overall enhancement has occurred in their integrative coordination.④Between 2023 and 2025,the level of integrative coordination in Zaozhuang is expected to rise steadily.However,reaching a state of advanced coordination will require additional time for development.
文摘Genetic diversity of 18 processing apple varieties and two fresh varieties were evaluated using 12 simple sequence repeats （SSR） primer pairs previously identified in Malus domestica Borkh. A total of 87 alleles in 10 loci were detected using 10 polymorphic SSR markers selected within the range of 5-14 alleles per locus. All the 20 varieties could be distinguished using two primer pairs and they were divided into four groups using cluster analysis. The genetic similarity （GS） of groups analyzed using cluster analysis varied from 0.14 to 0.83. High acid variety Avrolles separated from other varieties with GS less than 0.42. The second group contained Longfeng and Dolgo from Northeast of China, the inherited genes of Chinese crab apple. The five cider varieties with high tannin contents, namely, Dabinette, Frequin rouge, Kermerrien, M.Menard, and D.Coetligne were clustered into the third group. The fourth group was mainly composed of 12 juice and fresh varieties. Principal coordinate analysis （PCO） also divided all the varieties into four groups. Juice and fresh apple varieties, Longfeng and Dolgo were clustered together, respectively, using both the analyses. Both the analyses showed there was much difference between cider and juice varieties, cider and fresh varieties, as well as Chinese crab apple and western European crab apple, whereas juice varieties and fresh varieties had a similar genetic background. The genetic diversity and differentiation could be sufficiently reflected by combining the two analytical methods.
基金supported by the Foundation of Education Committee of Hunan Province(06C195)the Research Award Fund for Outstanding Young Teachers of Hengyang Normal University(2006)Supported by the construct program of the key discipline in hunan province.
文摘A one-dimensional chain coordination polymer [Cu（phen）（2,4,6-TMBA）2（H2O）]n has been synthesized by reacting 2,4,6-trimethyl-benzoic acid, 1,10-phenanthroline and Cu（Ⅱ） perchlorate and its structure was characterized. Crystal data for this complex： tetragonal, space group I41, a = 2.0293（3）, b = 2.0293（3）, c = 1.3758（2） nm, α =β= γ = 90°, V= 5.6657（13） nm3, Dc= 1.379 g/cm3, Z = 8, μ（MoKa） = 0.815 mm-1, Mr = 588.14, F（000） = 2456, S = 1.047, R = 0.0459 and wR = 0.1053. The crystal structure shows that two neighboring Cu（Ⅱ） ions are linked together by one bridging-chelating 2,4,6-trimethyl-benzoic group, forming a one-dimensional chain structure. Each Cu（Ⅱ） ion is coordinated with two nitrogen atoms from one 1,10-phenanthroline molecule, three oxygen atoms from three 2,4,6-trimethyl-benzoic acid molecules and one oxygen atom from one water molecule, giving a six-coordinate distorted octahedral coordination geometry. The cyclic voltammetry behavior of the complex was also investigated.
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Under the auspices of National Science and Technology Major Project (No.2009ZX07210)National Natural Science Foundation of China (No.40871261)
文摘During the rapid industrialization and urbanization of China,urban agglomeration in river basin areas raises the problems of over-use of water resources and pollution of the water environment.Related research in China has mainly focused on the conflicts among economic growth,urban expansion and water resource shortages within admin-istrative boundaries.However,water environments are much more dependent on their physical boundaries than their administrative boundaries.Consistent with the nature of water environment,this study aims at analyzing coordination relationships between urban development and water environment changes within physical river basin boundaries.We chose the Shayinghe River Basin,China,as our case study area which is facing serious challenges related to water en-vironment protection.Then we classified 35 county-level administrative units into upstream,midstream and down-stream regions based on their physical characteristics;analyzed the coordination degree of urban agglomeration using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method;and constructed cooperative models using the Linear Programming (LP function) to simulate four scenarios of the coordination relationship be-tween urban population increase and water environment protection based on existing water resources and water pollu-tion data.The results show that the present coordinative situation in Shayinghe River Basin is not sustainable.In gen-eral,more than 50% administrative units are in the bad coordinative situation.In particular,the downstream region is under worse condition than the upstream and midstream regions.Cooperative models in scenario analyses indicate that the population scale set in existing urban master plannings is not coordinated with the water environment protection.To reach the goal of regional sustainable development,the total population needs to be controlled such that it will re-main at 4.5×10 7 or below by 2020 given the capacity of water environment.
文摘One-dimensional chain copper（Ⅱ） coordination polymer has been synthesized and characterized in the solvent mixture of water and alcohol with o-acetamidobenzoic acid,4,4＇-bipyridine and copper perchlorate.It is of tetragonal,space group P41212 with a=1.57756（10）,b= 1.57756（10）,c=2.1438（3）nm,V=5.3352（8） nm^3,Dc=1.524 g/cm^3,Z=4,F（000）=2536,R= 0.0479 and wR=0.0979.The crystal structure shows two coordination modes.The copper（1） is coordinated with two nitrogen atoms of one 4,4＇-bipyridine molecule and two oxygen atoms from two o-acetamidobenzoic acid molecules,forming a distorted tetrahedral coordination geometry; the copper（2） is coordinated with two nitrogen atoms of one 4,4＇-bipyridine molecule,four oxygen atoms from two o-acetamidobenzoic acid molecules and two water molecules,generating a distorted octahedral coordination geometry.The result of TG analysis shows that the title complex is stable below 180.0 ℃.
基金Supported by the Foundation of Education Committee of Hunan Province (06C195)Fund for Construction of Key Subject in the Eleventh Five-year Plan of Higher Learning of Education in Hunan Province
文摘A novel one-dimensional chain coordination polymer [Mn（NAAh（4,4′-bipy）（H2O）4], has been synthesized with a-naphthaleneacetic acid, 4,4′-bipy and manganese（Ⅱ） sulfate as raw materials. Crystal data for this complex： monoclinic, space group P21/c, a = 1.1421（2）, b = 1.6337（3）, c = 0.94177（19） nm, β = 112.15（3）°, V = 1.6275（6） nm^3, De = 1.407 g/cm^3, Z = 2, μ（MoKa） = 0.467 mm^-1, F（000） = 722, S = 1.007, R= 0.0412 and wR = 0.1022. The crystal structure shows that two neighboring manganese（Ⅱ） ions are linked together by one 4,4′-bipy molecule, and the whole complex molecule forms a one-dimensional chain structure. Each manganese（Ⅱ） ion is coordinated with two oxygen atoms of two a-naphthaleneacetic acid molecules, two nitrogen atoms of two 4,4′-bipy molecules and two oxygen atoms from two water molecules, giving a distorted octahedral coordination geometry. The electrochemical properties were also analyzed.
基金Supported by the Liaoning Provincial Key R and D Guidance Plan Project in 2018,No.2018225009the Liaoning Colleges and Universities Basic Research Project,No.LFWK201710.
文摘BACKGROUND Gut microbiota is an emerging field of research,with related research having breakthrough development in the past 15 years.Bibliometric analysis can be applied to analyze the evolutionary trends and emerging hotspots in this field.AIM To study the subject trends and knowledge structures of gut microbiota related research fields from 2004 to 2018.METHODS The literature data on gut microbiota were identified and downloaded from the PubMed database.Through biclustering analysis,strategic diagrams,and social network analysis diagrams,the main trend and knowledge structure of research fields concerning gut microbiota were analyzed to obtain and compare the research hotspots in each period.RESULTS According to the strategic coordinates and social relationship network map,Clostridium Infections/microbiology,Clostridium Infections/therapy,RNA,Ribosomal,16S/genetics,Microbiota/genetics,Microbiota/immunology,Dysbiosis/immunology,Infla-mmation/immunology,Fecal Microbiota Transplantation/methods,Fecal Microbiota Transplantation can be used as an emerging research hotspot in the past 5 years(2014-2018).CONCLUSION Some subjects were not yet fully studied according to the strategic coordinates;and the emerging hotspots in the social network map can be considered as directions of future research.
