This paper deals with the problem of clutter suppression in spaceborne distributed synthetic aperture radar （D-SAR） with nonuniform three-dimensional （3D） configuration geometry. In order to make a breakthrough of...This paper deals with the problem of clutter suppression in spaceborne distributed synthetic aperture radar （D-SAR） with nonuniform three-dimensional （3D） configuration geometry. In order to make a breakthrough of the configuration limitation of the traditional space time adaptive processing （STAP） based on uniform array and improve the inhomogeneous clutter suppres- sion performance, this paper considers signal reconstrtiction technique using array interpolation to process the D-SAR signal. An array interpolation signal reconstruction method based on pitching-partition is derived then a signal reconstruction 3D-STAP clutter suppression method applied to nonuniform 3D configuration is proposed. In particular, the proposed method is compared with conventional methods and the performance analysis is carried out based on simulations. The improvement factor （IF） for clutter suppression is imported and reported as a benchmark on the clutter suppression effect.展开更多
Thermal metamaterial represents a groundbreaking approach to control heat conduction,and,as a crucial component,thermal invisibility is of utmost importance for heat management.Despite the flourishing development of t...Thermal metamaterial represents a groundbreaking approach to control heat conduction,and,as a crucial component,thermal invisibility is of utmost importance for heat management.Despite the flourishing development of thermal invisibility schemes,they still face two limitations in practical applications.First,objects are typically completely enclosed in traditional cloaks,making them difficult to use and unsuitable for objects with heat sources.Second,although some theoretical proposals have been put forth to change the thermal conductivity of materials to achieve dynamic invisibility,their designs are complex and rigid,making them unsuitable for large-scale use in real threedimensional(3D)spaces.Here,we propose a concept of a thermal dome to achieve 3D invisibility.Our scheme includes an open functional area,greatly enhancing its usability and applicability.It features a reconfigurable structure,constructed with simple isotropic natural materials,making it suitable for dynamic requirements.The performance of our reconfigurable thermal dome has been confirmed through simulations and experiments,consistent with the theory.The introduction of this concept can greatly advance the development of thermal invisibility technology from theory to engineering and provide inspiration for other physical domains,such as direct current electric fields and magnetic fields.展开更多
Dense cropping increases crop yield but intensifies resource competition,which reduces single plant yield and limits potential yield growth.Optimizing canopy spacing could enhance resource utilization,support crop mor...Dense cropping increases crop yield but intensifies resource competition,which reduces single plant yield and limits potential yield growth.Optimizing canopy spacing could enhance resource utilization,support crop morphological development and increase yield.Here,a three-year study was performed to verify the feasibility of adjusting row spacing to further enhance yield in densely planted soybeans.Of three row-spacing configurations(40-40,20-40,and 20-60 cm)and two planting densities(normal 180,000 plants ha 1 and high 270,000 plants ha 1).The differences in canopy structure,plant morphological development,photosynthetic capacity and their impact on yield were analyzed.Row spacing configurations have a significant effect on canopy transmittance(CT).The 20-60 cm row spacing configuration increased CT and creates a favorable canopy light environment,in which plant height is reduced,while branching is promoted.This approach reduces plant competition,optimizes the developments of leaf area per plant,specific leaf area,leaf area development rate,leaf area duration and photosynthetic physiological indices(F_(v)/F_(m),ETR,P_(n)).The significant increase of 11.9%-34.2%in canopy apparent photosynthesis(CAP)is attributed to the significant optimization of plant growth and photosynthetic physiology through CT,an important contributing factor to yield increases.The yield in the 20-60 cm treatment is 4.0%higher than in equidistant planting under normal planting density,but 5.9%under high density,primarily driven by CAP and pod number.These findings suggest that suitable row spacing configurations optimize the light environment for plants,promote source-sink transformation in soybeans,and further improve yield.In practice,a 20-60 cm row spacing configuration could be employed for high-density soybean planting to achieve a more substantial yield gain.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
Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)an...Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)and 3‐mercaptopropyl trimethoxysilane(MPS)to afford dual surface‐capped nano‐amendment HAPIDA/MPS.The structure of HAP‐IDA/MPS was characterized,and its adsorption performance for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)was evaluated.The total adsorption capacity of 0.10 g HAP‐IDA/MPS nano‐amendment for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)with an initial mass concentration of 20 mg·L^(-1) reached 13.7 mg·g^(-1),about 4.3 times as much as that of HAP.Notably,HAP‐IDA/MPS nano‐amendment displayed the highest immobilization rate for Hg^(2+),possibly because of its chemical reaction with-SH to form sulfide,possessing the lowest solubility product constant among a variety of metal sulfides.展开更多
In the context of the“dual carbon”goals,to address issues such as high energy consumption,high costs,and low power quality in the rapid development of electrified railways,this study focused on the China Railways Hi...In the context of the“dual carbon”goals,to address issues such as high energy consumption,high costs,and low power quality in the rapid development of electrified railways,this study focused on the China Railways High-Speed 5 Electric Multiple Unit and proposed a mathematical model and capacity optimization method for an onboard energy storage system using lithium batteries and supercapacitors as storage media.Firstly,considering the electrical characteristics,weight,and volume of the storage media,a mathematical model of the energy storage system was established.Secondly,to tackle problems related to energy consumption and power quality,an energy management strategy was proposed that comprehensively considers peak shaving and valley filling and power quality by controlling the charge/discharge thresholds of the storage system.Thecapacity optimization adopted a bilevel programming model,with the series/parallel number of storage modules as variables,considering constraints imposed by the Direct Current to Direct Current converter,train load,and space.An improved Particle Swarm Optimization algorithm and linear programming solver were used to solve specific cases.The results show that the proposed onboard energy storage system can effectively achieve energy savings,reduce consumption,and improve power qualitywhile meeting the load and space limitations of the train.展开更多
Liposarcoma is one of the most common soft tissue sarcomas,however,its occurrence rate is still rare compared to other cancers.Due to its rarity,in vitro experiments are an essential approach to elucidate liposarcoma ...Liposarcoma is one of the most common soft tissue sarcomas,however,its occurrence rate is still rare compared to other cancers.Due to its rarity,in vitro experiments are an essential approach to elucidate liposarcoma pathobiology.Conventional cell culture-based research(2D cell culture)is still playing a pivotal role,while several shortcomings have been recently under discussion.In vivo,mouse models are usually adopted for pre-clinical analyses with expectations to overcome the issues of 2D cell culture.However,they do not fully recapitulate human dedifferentiated liposarcoma(DDLPS)characteristics.Therefore,three-dimensional(3D)culture systems have been the recent research focus in the cell biology field with the expectation to overcome at the same time the disadvantages of 2D cell culture and in vivo animal models and fill in the gap between them.Given the liposarcoma rarity,we believe that 3D cell culture techniques,including 3D cell cultures/co-cultures,and Patient-Derived tumor Organoids(PDOs),represent a promising approach to facilitate liposarcoma investigation and elucidate its molecular mechanisms and effective therapy development.In this review,we first provide a general overview of 3D cell cultures compared to 2D cell cultures.We then focus on one of the recent 3D cell culture applications,Patient-Derived Organoids(PDOs),summarizing and discussing several PDO methodologies.Finally,we discuss the current and future applications of PDOs to sarcoma,particularly in the field of liposarcoma.展开更多
With the continuous application of new technologies in reconnaissance and attack, false camouflage plays a more important role in improving the survivability of targets, and the number of decoys plays a crucial role i...With the continuous application of new technologies in reconnaissance and attack, false camouflage plays a more important role in improving the survivability of targets, and the number of decoys plays a crucial role in the camouflaging effect. Based on the concept of cost-effectiveness ratio, according to the newly formulated Johnson criterion and the view of discovery and destruction, this paper proposes to take the identification probability as the probability of being destroyed and uses mathematical formulas to calculate the cost of a single use decoy. On this basis, a cost-effectiveness ratio model is established, with the product of the increase in the survival probability of the target and the cost of the target as the benefit, and the sum of the product of the probability of being destroyed and the cost of the decoy and the cost of a single use as the consumption cost. The model is calculated and analyzed, and the number of decoys that conform to the actual situation is obtained.展开更多
The three-dimensional particle electrode system exhibits significant potential for application in the treatment of wastewater.Nonetheless,the advancement of effective granular electrodes characterized by elevated cata...The three-dimensional particle electrode system exhibits significant potential for application in the treatment of wastewater.Nonetheless,the advancement of effective granular electrodes characterized by elevated catalytic activity and minimal energy consumption continues to pose a significant challenge.In this research,Fluorine-doped copper-carbon(F/Cu-GAC)particle electrodes were effectively synthesized through an impregnationcalcination technique,utilizing granular activated carbon as the carrier and fluorinedoped modified copper oxides as the catalytic agents.The particle electrodes were subsequently utilized to promote the degradation of 2,4,6-trichlorophenol(2,4,6-TCP)in a threedimensional electrocatalytic reactor(3DER).The F/Cu-GAC particle electrodes were polarized under the action of electric field,which promoted the heterogeneous Fenton-like reaction in which H2O2 generated by two-electron oxygen reduction reaction(2e-ORR)of O_(2) was catalytically decomposed to·OH.The 3DER equipped with F/Cu-GAC particle electrodes showed 100%removal of 2,4,6-TCP and 79.24%removal of TOC with a specific energy consumption(EC)of approximately 0.019 kWh/g·COD after 2 h of operation.The F/Cu-GAC particle electrodes exhibited an overpotential of 0.38 V and an electrochemically active surface area(ECSA)of 715 cm^(2),as determined through linear sweep voltammetry(LSV)and cyclic voltammetry(CV)assessments.These findings suggest a high level of electrocatalytic performance.Furthermore,the catalytic mechanism of the 3DER equipped with F/Cu-GAC particle electrodes was elucidated through the application of X-ray photoelectron spectroscopy(XPS),electron spin resonance(ESR),and active species capture experiments.This investigation offers a novel approach for the effective degradation of 2,4,6-TCP.展开更多
With the increase in the quantity and scale of Static Random-Access Memory Field Programmable Gate Arrays (SRAM-based FPGAs) for aerospace application, the volume of FPGA configuration bit files that must be stored ha...With the increase in the quantity and scale of Static Random-Access Memory Field Programmable Gate Arrays (SRAM-based FPGAs) for aerospace application, the volume of FPGA configuration bit files that must be stored has increased dramatically. The use of compression techniques for these bitstream files is emerging as a key strategy to alleviate the burden on storage resources. Due to the severe resource constraints of space-based electronics and the unique application environment, the simplicity, efficiency and robustness of the decompression circuitry is also a key design consideration. Through comparative analysis current bitstream file compression technologies, this research suggests that the Lempel Ziv Oberhumer (LZO) compression algorithm is more suitable for satellite applications. This paper also delves into the compression process and format of the LZO compression algorithm, as well as the inherent characteristics of configuration bitstream files. We propose an improved algorithm based on LZO for bitstream file compression, which optimises the compression process by refining the format and reducing the offset. Furthermore, a low-cost, robust decompression hardware architecture is proposed based on this method. Experimental results show that the compression speed of the improved LZO algorithm is increased by 3%, the decompression hardware cost is reduced by approximately 60%, and the compression ratio is slightly reduced by 0.47%.展开更多
A substation is a complex coupled system composed of various electrical equipment.Compared with standalone equipment,there is a significant coupling effect in the seismic response of interconnected equipment.To addres...A substation is a complex coupled system composed of various electrical equipment.Compared with standalone equipment,there is a significant coupling effect in the seismic response of interconnected equipment.To address this issue,this study investigates the seismic interaction of substation equipment with multiple electrical configurations and proposes an improved seismic design method.First,the concept of the coupling coefficient is introduced,which is used to improve the Newmark-βmethod and response spectrum method for the seismic design of standalone equipment.Then,the finite element models of a substation system with multiple configurations are established,and the vibration characteristics and seismic responses of the interconnected equipment are investigated.Finally,the coupling coefficients are obtained by kernel density estimation of the response results under twenty seismic ground motions,and the effectiveness of the proposed method is verified through two numerical examples.The results show that the frequency coupling coefficients vary from 0.69 to 1.42,while the seismic action coupling coefficient has a wider range,changing from 1.04 to 3.91.The coupling effect amplifies the seismic response of higher-frequency equipment,and the amplification degree varies among different configurations for the same type of equipment.展开更多
Solution environment can influence the flexible structure of DNA under specific conditions,thereby affecting the stability of nucleic acids and ultimately impacting critical biological processes such as replication an...Solution environment can influence the flexible structure of DNA under specific conditions,thereby affecting the stability of nucleic acids and ultimately impacting critical biological processes such as replication and transcription.Intracellular solution environment is variable,and previous studies have demonstrated that it can enhance the stability of DNA structures under certain circumstances.In this work,molecular dynamics simulations were conducted on B-DNA(1ZEW,with a nucleotide sequence of CCTCTAGAGG)derived from human breast cancer cells(MDA-MB231)to explore the effects of ethanol solution on DNA configuration transformation at different temperatures and concentrations.The calculated results indicate that ethanol facilitates the transition of 1ZEW from B-DNA to A-DNA at lower temperature.Furthermore,it is observed that temperature affects DNA structure to some extent,thereby modifying the trend in DNA configuration transformation.At low temperatures,the ethanol can promote the transformation of B-DNA into A-DNA at higher concentrations.While at higher temperatures,the DNA could be in a state of thermal melting.These conclusions presented here can give valuable insights into how ethanol affects B-DNA configuration transformations.展开更多
Two novel diketopiperazines(1 and 5),along with ten known compounds(2−4,6−12)demonstrating significant skin inflammation inhibition,were isolated from a marine-derived fungus identified as Aspergillus sp.FAZW0001.The ...Two novel diketopiperazines(1 and 5),along with ten known compounds(2−4,6−12)demonstrating significant skin inflammation inhibition,were isolated from a marine-derived fungus identified as Aspergillus sp.FAZW0001.The structural elucidation and configurational reassessments of compounds 1−5 were established through comprehensive spectral analyses,with their absolute configurations determined via single crystal X-ray diffraction using Cu Kαradiation,Marfey’s method,and comparison between experimental and calculated electronic circular dichroism(ECD)spectra.Compounds 1,2,and 8 exhibited significant anti-inflammatory activities in Propionibacterium acnes(P.acnes)-induced human monocyte cell lines.Compound 8 demonstrated the ability to down-regulate interleukin-1β(IL-1β)expression by inhibiting Toll-like receptor 2(TLR2)expression and modulating the activation of myeloid differentiation factor 88(MyD88),mitogen-activated protein kinase(MAPK),and nuclear factorκB(NF-κB)signaling pathways,thus reducing the cellular inflammatory response induced by P.acnes.Additionally,compound 8 showed the capacity to suppress mitochondrial reactive oxygen species(ROS)production and nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome activation,thereby reducing IL-1βmaturation and secretion.A three-dimensional quantitative structure-activity relationships(3D-QSAR)model was applied to compounds 5−12 to analyze their anti-inflammatory structure-activity relationships.展开更多
In this study,CiteSpace software is used to carry out visual analysis on the three-dimensional research literature on urban recreation space from the perspective of compact city theory in the past 20 years,exploring t...In this study,CiteSpace software is used to carry out visual analysis on the three-dimensional research literature on urban recreation space from the perspective of compact city theory in the past 20 years,exploring the scientific development trend and research hotspots in this field.The results show that the number of published documents shows a fluctuating upward trend,and the significant growth rate reflects the role of policy orientation in promoting the concept of compact city.The co-occurrence analysis of keywords reveals the research hotspots of“compact city”,“recreation space”and“urban park”,while the emergence of new keywords such as“vertical city”and“spatial justice”indicates the new trend of recent research.The cluster analysis and timeline map further show the evolution of research themes,with“compact city”being the largest cluster and having rich connections with other themes such as“urban design”and“urban park”.展开更多
HOMER(Hybrid OptimizationModel for Electric Renewables)is an effective simulation and optimization platform for hybrid renewable energy.By inputting specific users’energy resource data(such as wind speed,solar radiat...HOMER(Hybrid OptimizationModel for Electric Renewables)is an effective simulation and optimization platform for hybrid renewable energy.By inputting specific users’energy resource data(such as wind speed,solar radiation,etc.)and load data,and by determining the types and models of components selected by the user,HOMER calculates and simulates the operational status of each component at every time step.Ultimately,it computes the energy balance of the system within specified constraints to simulate the overall system operation.This approach enables the reasonable determination of system component capacities,the evaluation of system feasibility,and the calculation of costs over the entire lifecycle of the system.In response to the challenges of matching capacities and high construction costs in wind-solar-storage multi-energy complementary power generation systems,This paper addresses issues such as difficulty in matching component capacities,high construction costs,and low system reliability in multi-energy complementary power generation systems.Using the HOMER hybrid renewable energy simulation and optimization platform,we constructed various hybrid energy systems for a specific region and considered multiple power supply modes.Thesoftware was used to solve for the optimal capacities and costs of each system.Four scenarios were analyzed:grid-only,grid-connected(purchase-sale)wind-solar-storage system,grid-connected(sale)wind-solar-storage system,and off-grid wind-solar-storage system.The results were compared and analyzed.HOMER can assess systemfeasibility and calculate the cost over its entire lifecycle.By inputting 8760 h of wind and solar resource data and load data for a specific region,and considering multiple system structures and power supply modes,the configuration results were evaluated using indicators such as cost and renewable energy utilization ratio.The simulation results indicate that the Net Present Cost(NPC)values across four different scenarios range from 1,877,292 CNY to 3,222,724 CNY,demonstrating significant cost differences.Among these scenarios,the grid-connected(purchase-sell)wind-solarstorage system exhibited the lowest NPC and the highest renewable energy utilization rate.Compared to a system relying solely on the grid,the NPC was reduced by 305,695 CNY,and the renewable energy utilization rate reached 74.7%.展开更多
BACKGROUND Ganglioneuroma is a rare,well-differentiated,slow-growing benign tumor of the peripheral nerves,with surgical resection being the only curative treatment.Surgical resection of ganglioneuromas encasing major...BACKGROUND Ganglioneuroma is a rare,well-differentiated,slow-growing benign tumor of the peripheral nerves,with surgical resection being the only curative treatment.Surgical resection of ganglioneuromas encasing major blood vessels remains a substantial clinical challenge.Traditionally,these cases often require open abdominal surgery or combined organ resections,and in some instances,the tumors are considered unresectable.Currently,no reports have described the resection of such tumors via laparoscopy.CASE SUMMARY A 35-year-old woman was admitted to our hospital after the incidental discovery of a retroperitoneal space-occupying lesion.Imaging revealed a mass with the celiac axis and superior mesenteric artery passing through it.A neurogenic tumor was suspected,with ganglioneuroma being the most likely diagnosis.Following comprehensive preoperative preparation,the retroperitoneal tumor was resected using a three-dimensional laparoscopy combined with an organ suspension technique.The surgical approach involved incising the tumor along the vascular axis and conducting meticulous,vascular-preserving tumor excision.The operation lasted approximately 458 minutes,with an estimated blood loss of 50 mL.The patient was discharged on the 8th postoperative day.A transient liver injury occurred after surgery but improved rapidly.After 11 months of postoperative follow-up,no complications or tumor recurrence were observed.CONCLUSION This case illustrates the feasibility of minimally invasive laparoscopic resection for retroperitoneal ganglioneuromas encasing major blood vessels.展开更多
In response to the issue of determining the appropriate capacity when hybrid energy storage systems(HESS)collaborate with thermal power units(TPU)in the system’s secondary frequency regulation,a configuration method ...In response to the issue of determining the appropriate capacity when hybrid energy storage systems(HESS)collaborate with thermal power units(TPU)in the system’s secondary frequency regulation,a configuration method for HESS based on the analysis of frequency regulation demand analysis is proposed.And a corresponding simulation platform is developed.Firstly,a frequency modulation demand method for reducing the frequency modulation losses of TPU is proposed.Secondly,taking into comprehensive consideration that flywheel energy storage features rapid power response and battery energy storage has the characteristic of high energy density,a coordinated control strategy for HESS considering the self-recovery of state of charge(SOC)is put forward.Then,to measure the economic and technical performance of HESS in assisting the secondary frequency modulation of TPU,an optimized configurationmodel considering the full-life-cycle economy and frequency modulation performance of TPU and HESS system is constructed.Finally,a visual simulation platform for the combined frequency modulation of TPU and HESS is developed based on Matlab Appdesigner.Theresults of calculation examples indicate that the proposed configuration method can improve the overall economic efficiency and frequency modulation performance of TPU and HESS;The control strategy can not only prolong the service life of battery energy storage but also enhance the continuous response ability of HESS;The visual simulation platform is easy to use,and the simulation results are accurate and reliable.展开更多
By analyzing the urgent demand for digital talents in the current landscape industry and the challenges faced by the traditional teaching mode,this study aims to explore a set of teaching methodology reform solutions ...By analyzing the urgent demand for digital talents in the current landscape industry and the challenges faced by the traditional teaching mode,this study aims to explore a set of teaching methodology reform solutions based on digital technology to improve the quality of teaching and enhance the practical innovation ability of students.The study firstly describes the application of digital technologies such as CAD/BIM,3D modelling and rendering,virtual reality(VR)/augmented reality(AR),and geographic information system(GIS)in the field of landscape architecture.Then,the current teaching status of plant configuration and landscape architecture courses is analyzed,and the advantages and challenges of digital technology applications are identified.On this basis,this study proposes a multi-dimensional reform path and practice plan including the reconstruction of teaching objectives and content,innovation of teaching mode,improvement of teaching strategies and methods,as well as the construction of teaching resources and the reform of teaching evaluation,guided by modern educational theories such as constructivism,collaborative learning and project-based learning(PBL).Finally,this study emphasizes the key roles of faculty construction,optimization of hardware and software environment,and teaching management and institutional guarantee in the reform.展开更多
The three-dimensional spectral analysis method was applied to airglow data from September 2023 to August 2024 derivedfrom an OH airglow imager located at the Hejing station (42.79°N, 83.73°E) to study the pr...The three-dimensional spectral analysis method was applied to airglow data from September 2023 to August 2024 derivedfrom an OH airglow imager located at the Hejing station (42.79°N, 83.73°E) to study the propagation characteristics of gravity waves(GWs) over Northwest China. We found that obvious seasonal variations occur in the propagation of GWs. In spring, GWs mainlypropagate in the northeast direction. In summer and autumn, GWs mainly propagate in the north direction. However, GWs mainlypropagate in the south direction in winter. The direction of GW propagation in the zonal direction is controlled by the wind-filteringeffect, whereas the north–south meridional direction is mainly determined by the location of the wave source. We found that the averageenergy spectrum exhibits a 10%–20% higher intensity in summer and winter compared with spring and autumn. For the first time, wereport the seasonal variation characteristics of GWs over the inland areas of Northwest China, which is of great significance forunderstanding the regional distribution characteristics of GWs.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
基金2011 China Aerospace Science and Technology Corporation Aerospace Science and Technology Innovation Foundation Subsidized Project2011 CASC and HIT Joint Technology Innovation Foundation
文摘This paper deals with the problem of clutter suppression in spaceborne distributed synthetic aperture radar （D-SAR） with nonuniform three-dimensional （3D） configuration geometry. In order to make a breakthrough of the configuration limitation of the traditional space time adaptive processing （STAP） based on uniform array and improve the inhomogeneous clutter suppres- sion performance, this paper considers signal reconstrtiction technique using array interpolation to process the D-SAR signal. An array interpolation signal reconstruction method based on pitching-partition is derived then a signal reconstruction 3D-STAP clutter suppression method applied to nonuniform 3D configuration is proposed. In particular, the proposed method is compared with conventional methods and the performance analysis is carried out based on simulations. The improvement factor （IF） for clutter suppression is imported and reported as a benchmark on the clutter suppression effect.
基金supported by the National Natural Science Foundation of China to Jiping Huang(12035004 and 12320101004)the Innovation Program of the Shanghai Municipal Education Commission to Jiping Huang(2023ZKZD06)+2 种基金the National Natural Science Foundation of China to Ying Li(92163123 and 52250191)the Zhejiang Provincial Natural Science Foundation of China to Ying Li(LZ24A050002)the National Natural Science Foundation of China to Liujun Xu(12375040,12088101,and U2330401).
文摘Thermal metamaterial represents a groundbreaking approach to control heat conduction,and,as a crucial component,thermal invisibility is of utmost importance for heat management.Despite the flourishing development of thermal invisibility schemes,they still face two limitations in practical applications.First,objects are typically completely enclosed in traditional cloaks,making them difficult to use and unsuitable for objects with heat sources.Second,although some theoretical proposals have been put forth to change the thermal conductivity of materials to achieve dynamic invisibility,their designs are complex and rigid,making them unsuitable for large-scale use in real threedimensional(3D)spaces.Here,we propose a concept of a thermal dome to achieve 3D invisibility.Our scheme includes an open functional area,greatly enhancing its usability and applicability.It features a reconfigurable structure,constructed with simple isotropic natural materials,making it suitable for dynamic requirements.The performance of our reconfigurable thermal dome has been confirmed through simulations and experiments,consistent with the theory.The introduction of this concept can greatly advance the development of thermal invisibility technology from theory to engineering and provide inspiration for other physical domains,such as direct current electric fields and magnetic fields.
基金supported by the Biological Breeding-National Science and Technology Major Project(2023ZD0403305)National Natural Science Foundation of China(32101845)+1 种基金the National Key Research and Development Program of China(2023YFE0105000)the China Agriculture Research System(CARS-04).
文摘Dense cropping increases crop yield but intensifies resource competition,which reduces single plant yield and limits potential yield growth.Optimizing canopy spacing could enhance resource utilization,support crop morphological development and increase yield.Here,a three-year study was performed to verify the feasibility of adjusting row spacing to further enhance yield in densely planted soybeans.Of three row-spacing configurations(40-40,20-40,and 20-60 cm)and two planting densities(normal 180,000 plants ha 1 and high 270,000 plants ha 1).The differences in canopy structure,plant morphological development,photosynthetic capacity and their impact on yield were analyzed.Row spacing configurations have a significant effect on canopy transmittance(CT).The 20-60 cm row spacing configuration increased CT and creates a favorable canopy light environment,in which plant height is reduced,while branching is promoted.This approach reduces plant competition,optimizes the developments of leaf area per plant,specific leaf area,leaf area development rate,leaf area duration and photosynthetic physiological indices(F_(v)/F_(m),ETR,P_(n)).The significant increase of 11.9%-34.2%in canopy apparent photosynthesis(CAP)is attributed to the significant optimization of plant growth and photosynthetic physiology through CT,an important contributing factor to yield increases.The yield in the 20-60 cm treatment is 4.0%higher than in equidistant planting under normal planting density,but 5.9%under high density,primarily driven by CAP and pod number.These findings suggest that suitable row spacing configurations optimize the light environment for plants,promote source-sink transformation in soybeans,and further improve yield.In practice,a 20-60 cm row spacing configuration could be employed for high-density soybean planting to achieve a more substantial yield gain.
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.
文摘Hydroxyapatite nanoparticles(HAP NPs)were synthesized by a one‐step hydrothermal method.The surface of HAP NPs was grafted-SH and-COOH chelating groups via in situ surface‐modification with iminodiacetic acid(IDA)and 3‐mercaptopropyl trimethoxysilane(MPS)to afford dual surface‐capped nano‐amendment HAPIDA/MPS.The structure of HAP‐IDA/MPS was characterized,and its adsorption performance for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)was evaluated.The total adsorption capacity of 0.10 g HAP‐IDA/MPS nano‐amendment for Hg^(2+),Cu^(2+),Zn^(2+),Ni^(2+),Co^(2+),and Cd^(2+)with an initial mass concentration of 20 mg·L^(-1) reached 13.7 mg·g^(-1),about 4.3 times as much as that of HAP.Notably,HAP‐IDA/MPS nano‐amendment displayed the highest immobilization rate for Hg^(2+),possibly because of its chemical reaction with-SH to form sulfide,possessing the lowest solubility product constant among a variety of metal sulfides.
基金funded by the National Natural Science Foundation of China(52167013)the Key Program of Natural Science Foundation of Gansu Province(24JRRA225)Natural Science Foundation of Gansu Province(23JRRA891).
文摘In the context of the“dual carbon”goals,to address issues such as high energy consumption,high costs,and low power quality in the rapid development of electrified railways,this study focused on the China Railways High-Speed 5 Electric Multiple Unit and proposed a mathematical model and capacity optimization method for an onboard energy storage system using lithium batteries and supercapacitors as storage media.Firstly,considering the electrical characteristics,weight,and volume of the storage media,a mathematical model of the energy storage system was established.Secondly,to tackle problems related to energy consumption and power quality,an energy management strategy was proposed that comprehensively considers peak shaving and valley filling and power quality by controlling the charge/discharge thresholds of the storage system.Thecapacity optimization adopted a bilevel programming model,with the series/parallel number of storage modules as variables,considering constraints imposed by the Direct Current to Direct Current converter,train load,and space.An improved Particle Swarm Optimization algorithm and linear programming solver were used to solve specific cases.The results show that the proposed onboard energy storage system can effectively achieve energy savings,reduce consumption,and improve power qualitywhile meeting the load and space limitations of the train.
文摘Liposarcoma is one of the most common soft tissue sarcomas,however,its occurrence rate is still rare compared to other cancers.Due to its rarity,in vitro experiments are an essential approach to elucidate liposarcoma pathobiology.Conventional cell culture-based research(2D cell culture)is still playing a pivotal role,while several shortcomings have been recently under discussion.In vivo,mouse models are usually adopted for pre-clinical analyses with expectations to overcome the issues of 2D cell culture.However,they do not fully recapitulate human dedifferentiated liposarcoma(DDLPS)characteristics.Therefore,three-dimensional(3D)culture systems have been the recent research focus in the cell biology field with the expectation to overcome at the same time the disadvantages of 2D cell culture and in vivo animal models and fill in the gap between them.Given the liposarcoma rarity,we believe that 3D cell culture techniques,including 3D cell cultures/co-cultures,and Patient-Derived tumor Organoids(PDOs),represent a promising approach to facilitate liposarcoma investigation and elucidate its molecular mechanisms and effective therapy development.In this review,we first provide a general overview of 3D cell cultures compared to 2D cell cultures.We then focus on one of the recent 3D cell culture applications,Patient-Derived Organoids(PDOs),summarizing and discussing several PDO methodologies.Finally,we discuss the current and future applications of PDOs to sarcoma,particularly in the field of liposarcoma.
文摘With the continuous application of new technologies in reconnaissance and attack, false camouflage plays a more important role in improving the survivability of targets, and the number of decoys plays a crucial role in the camouflaging effect. Based on the concept of cost-effectiveness ratio, according to the newly formulated Johnson criterion and the view of discovery and destruction, this paper proposes to take the identification probability as the probability of being destroyed and uses mathematical formulas to calculate the cost of a single use decoy. On this basis, a cost-effectiveness ratio model is established, with the product of the increase in the survival probability of the target and the cost of the target as the benefit, and the sum of the product of the probability of being destroyed and the cost of the decoy and the cost of a single use as the consumption cost. The model is calculated and analyzed, and the number of decoys that conform to the actual situation is obtained.
基金supported by Guangxi Science and Technology Major Program(No.AA23073008)Hubei Key Laboratory of Water System Science for Sponge City Construction(Wuhan University)(No.2023–05)Nanning Innovation and Entrepreneur Leading Talent Project(No.2021001).
文摘The three-dimensional particle electrode system exhibits significant potential for application in the treatment of wastewater.Nonetheless,the advancement of effective granular electrodes characterized by elevated catalytic activity and minimal energy consumption continues to pose a significant challenge.In this research,Fluorine-doped copper-carbon(F/Cu-GAC)particle electrodes were effectively synthesized through an impregnationcalcination technique,utilizing granular activated carbon as the carrier and fluorinedoped modified copper oxides as the catalytic agents.The particle electrodes were subsequently utilized to promote the degradation of 2,4,6-trichlorophenol(2,4,6-TCP)in a threedimensional electrocatalytic reactor(3DER).The F/Cu-GAC particle electrodes were polarized under the action of electric field,which promoted the heterogeneous Fenton-like reaction in which H2O2 generated by two-electron oxygen reduction reaction(2e-ORR)of O_(2) was catalytically decomposed to·OH.The 3DER equipped with F/Cu-GAC particle electrodes showed 100%removal of 2,4,6-TCP and 79.24%removal of TOC with a specific energy consumption(EC)of approximately 0.019 kWh/g·COD after 2 h of operation.The F/Cu-GAC particle electrodes exhibited an overpotential of 0.38 V and an electrochemically active surface area(ECSA)of 715 cm^(2),as determined through linear sweep voltammetry(LSV)and cyclic voltammetry(CV)assessments.These findings suggest a high level of electrocatalytic performance.Furthermore,the catalytic mechanism of the 3DER equipped with F/Cu-GAC particle electrodes was elucidated through the application of X-ray photoelectron spectroscopy(XPS),electron spin resonance(ESR),and active species capture experiments.This investigation offers a novel approach for the effective degradation of 2,4,6-TCP.
基金supported in part by the National Key Laboratory of Science and Technology on Space Microwave(Grant Nos.HTKJ2022KL504009 and HTKJ2022KL5040010).
文摘With the increase in the quantity and scale of Static Random-Access Memory Field Programmable Gate Arrays (SRAM-based FPGAs) for aerospace application, the volume of FPGA configuration bit files that must be stored has increased dramatically. The use of compression techniques for these bitstream files is emerging as a key strategy to alleviate the burden on storage resources. Due to the severe resource constraints of space-based electronics and the unique application environment, the simplicity, efficiency and robustness of the decompression circuitry is also a key design consideration. Through comparative analysis current bitstream file compression technologies, this research suggests that the Lempel Ziv Oberhumer (LZO) compression algorithm is more suitable for satellite applications. This paper also delves into the compression process and format of the LZO compression algorithm, as well as the inherent characteristics of configuration bitstream files. We propose an improved algorithm based on LZO for bitstream file compression, which optimises the compression process by refining the format and reducing the offset. Furthermore, a low-cost, robust decompression hardware architecture is proposed based on this method. Experimental results show that the compression speed of the improved LZO algorithm is increased by 3%, the decompression hardware cost is reduced by approximately 60%, and the compression ratio is slightly reduced by 0.47%.
基金National Natural Science Foundation of China under Grant No. 52378483the Fundamental Research Funds for the Central Universities under Grant No. DUT21JC07+1 种基金the Scientific Research Fund of Institute of Engineering MechanicsChina Earthquake Administration under Grant No. 2021D17
文摘A substation is a complex coupled system composed of various electrical equipment.Compared with standalone equipment,there is a significant coupling effect in the seismic response of interconnected equipment.To address this issue,this study investigates the seismic interaction of substation equipment with multiple electrical configurations and proposes an improved seismic design method.First,the concept of the coupling coefficient is introduced,which is used to improve the Newmark-βmethod and response spectrum method for the seismic design of standalone equipment.Then,the finite element models of a substation system with multiple configurations are established,and the vibration characteristics and seismic responses of the interconnected equipment are investigated.Finally,the coupling coefficients are obtained by kernel density estimation of the response results under twenty seismic ground motions,and the effectiveness of the proposed method is verified through two numerical examples.The results show that the frequency coupling coefficients vary from 0.69 to 1.42,while the seismic action coupling coefficient has a wider range,changing from 1.04 to 3.91.The coupling effect amplifies the seismic response of higher-frequency equipment,and the amplification degree varies among different configurations for the same type of equipment.
基金supported by the National Natural Science Foun-dation of China(Grant Nos.52073128 and 11964012)the Foundation of Educational Committee of Jiangxi Province of China(Grant No.GJJ2201314).
文摘Solution environment can influence the flexible structure of DNA under specific conditions,thereby affecting the stability of nucleic acids and ultimately impacting critical biological processes such as replication and transcription.Intracellular solution environment is variable,and previous studies have demonstrated that it can enhance the stability of DNA structures under certain circumstances.In this work,molecular dynamics simulations were conducted on B-DNA(1ZEW,with a nucleotide sequence of CCTCTAGAGG)derived from human breast cancer cells(MDA-MB231)to explore the effects of ethanol solution on DNA configuration transformation at different temperatures and concentrations.The calculated results indicate that ethanol facilitates the transition of 1ZEW from B-DNA to A-DNA at lower temperature.Furthermore,it is observed that temperature affects DNA structure to some extent,thereby modifying the trend in DNA configuration transformation.At low temperatures,the ethanol can promote the transformation of B-DNA into A-DNA at higher concentrations.While at higher temperatures,the DNA could be in a state of thermal melting.These conclusions presented here can give valuable insights into how ethanol affects B-DNA configuration transformations.
基金supported by the National Natural Science Foundation of China(Nos.41876189 and 81703388)the State Key Laboratory of Bioreactor Engineering and Shanghai Collaborative Innovation Center for Biomanufacturing Technology.
文摘Two novel diketopiperazines(1 and 5),along with ten known compounds(2−4,6−12)demonstrating significant skin inflammation inhibition,were isolated from a marine-derived fungus identified as Aspergillus sp.FAZW0001.The structural elucidation and configurational reassessments of compounds 1−5 were established through comprehensive spectral analyses,with their absolute configurations determined via single crystal X-ray diffraction using Cu Kαradiation,Marfey’s method,and comparison between experimental and calculated electronic circular dichroism(ECD)spectra.Compounds 1,2,and 8 exhibited significant anti-inflammatory activities in Propionibacterium acnes(P.acnes)-induced human monocyte cell lines.Compound 8 demonstrated the ability to down-regulate interleukin-1β(IL-1β)expression by inhibiting Toll-like receptor 2(TLR2)expression and modulating the activation of myeloid differentiation factor 88(MyD88),mitogen-activated protein kinase(MAPK),and nuclear factorκB(NF-κB)signaling pathways,thus reducing the cellular inflammatory response induced by P.acnes.Additionally,compound 8 showed the capacity to suppress mitochondrial reactive oxygen species(ROS)production and nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome activation,thereby reducing IL-1βmaturation and secretion.A three-dimensional quantitative structure-activity relationships(3D-QSAR)model was applied to compounds 5−12 to analyze their anti-inflammatory structure-activity relationships.
基金Sponsored by the Project of Sichuan Landscape and Recreation Research Center(JGYQ2020037).
文摘In this study,CiteSpace software is used to carry out visual analysis on the three-dimensional research literature on urban recreation space from the perspective of compact city theory in the past 20 years,exploring the scientific development trend and research hotspots in this field.The results show that the number of published documents shows a fluctuating upward trend,and the significant growth rate reflects the role of policy orientation in promoting the concept of compact city.The co-occurrence analysis of keywords reveals the research hotspots of“compact city”,“recreation space”and“urban park”,while the emergence of new keywords such as“vertical city”and“spatial justice”indicates the new trend of recent research.The cluster analysis and timeline map further show the evolution of research themes,with“compact city”being the largest cluster and having rich connections with other themes such as“urban design”and“urban park”.
基金supported in part by the Inner Mongolia Autonomous Region Science and Technology Project Fund(2021GG0336)Inner Mongolia Natural Science Fund(2023ZD20).
文摘HOMER(Hybrid OptimizationModel for Electric Renewables)is an effective simulation and optimization platform for hybrid renewable energy.By inputting specific users’energy resource data(such as wind speed,solar radiation,etc.)and load data,and by determining the types and models of components selected by the user,HOMER calculates and simulates the operational status of each component at every time step.Ultimately,it computes the energy balance of the system within specified constraints to simulate the overall system operation.This approach enables the reasonable determination of system component capacities,the evaluation of system feasibility,and the calculation of costs over the entire lifecycle of the system.In response to the challenges of matching capacities and high construction costs in wind-solar-storage multi-energy complementary power generation systems,This paper addresses issues such as difficulty in matching component capacities,high construction costs,and low system reliability in multi-energy complementary power generation systems.Using the HOMER hybrid renewable energy simulation and optimization platform,we constructed various hybrid energy systems for a specific region and considered multiple power supply modes.Thesoftware was used to solve for the optimal capacities and costs of each system.Four scenarios were analyzed:grid-only,grid-connected(purchase-sale)wind-solar-storage system,grid-connected(sale)wind-solar-storage system,and off-grid wind-solar-storage system.The results were compared and analyzed.HOMER can assess systemfeasibility and calculate the cost over its entire lifecycle.By inputting 8760 h of wind and solar resource data and load data for a specific region,and considering multiple system structures and power supply modes,the configuration results were evaluated using indicators such as cost and renewable energy utilization ratio.The simulation results indicate that the Net Present Cost(NPC)values across four different scenarios range from 1,877,292 CNY to 3,222,724 CNY,demonstrating significant cost differences.Among these scenarios,the grid-connected(purchase-sell)wind-solarstorage system exhibited the lowest NPC and the highest renewable energy utilization rate.Compared to a system relying solely on the grid,the NPC was reduced by 305,695 CNY,and the renewable energy utilization rate reached 74.7%.
基金Supported by the Zhejiang Medical Science and Technology Project,No.2022KY1325 and No.2023KY381Public Welfare Project of Jinhua Science and Technology Plan,No.2023-4-084Major Project of Jinhua Science and Technology Plan,No.2023-3-066.
文摘BACKGROUND Ganglioneuroma is a rare,well-differentiated,slow-growing benign tumor of the peripheral nerves,with surgical resection being the only curative treatment.Surgical resection of ganglioneuromas encasing major blood vessels remains a substantial clinical challenge.Traditionally,these cases often require open abdominal surgery or combined organ resections,and in some instances,the tumors are considered unresectable.Currently,no reports have described the resection of such tumors via laparoscopy.CASE SUMMARY A 35-year-old woman was admitted to our hospital after the incidental discovery of a retroperitoneal space-occupying lesion.Imaging revealed a mass with the celiac axis and superior mesenteric artery passing through it.A neurogenic tumor was suspected,with ganglioneuroma being the most likely diagnosis.Following comprehensive preoperative preparation,the retroperitoneal tumor was resected using a three-dimensional laparoscopy combined with an organ suspension technique.The surgical approach involved incising the tumor along the vascular axis and conducting meticulous,vascular-preserving tumor excision.The operation lasted approximately 458 minutes,with an estimated blood loss of 50 mL.The patient was discharged on the 8th postoperative day.A transient liver injury occurred after surgery but improved rapidly.After 11 months of postoperative follow-up,no complications or tumor recurrence were observed.CONCLUSION This case illustrates the feasibility of minimally invasive laparoscopic resection for retroperitoneal ganglioneuromas encasing major blood vessels.
基金supported by a Key Project of the National Natural Science Foundation of China under Grant 52337004.
文摘In response to the issue of determining the appropriate capacity when hybrid energy storage systems(HESS)collaborate with thermal power units(TPU)in the system’s secondary frequency regulation,a configuration method for HESS based on the analysis of frequency regulation demand analysis is proposed.And a corresponding simulation platform is developed.Firstly,a frequency modulation demand method for reducing the frequency modulation losses of TPU is proposed.Secondly,taking into comprehensive consideration that flywheel energy storage features rapid power response and battery energy storage has the characteristic of high energy density,a coordinated control strategy for HESS considering the self-recovery of state of charge(SOC)is put forward.Then,to measure the economic and technical performance of HESS in assisting the secondary frequency modulation of TPU,an optimized configurationmodel considering the full-life-cycle economy and frequency modulation performance of TPU and HESS system is constructed.Finally,a visual simulation platform for the combined frequency modulation of TPU and HESS is developed based on Matlab Appdesigner.Theresults of calculation examples indicate that the proposed configuration method can improve the overall economic efficiency and frequency modulation performance of TPU and HESS;The control strategy can not only prolong the service life of battery energy storage but also enhance the continuous response ability of HESS;The visual simulation platform is easy to use,and the simulation results are accurate and reliable.
基金Chongqing Institute of Engineering 2023 Education Teaching Reform Research Project,“Exploration of Teaching Methods Reform of Plant Configuration and Landscape Architecture Curriculum under Digital Technology”(Project No.:JY2023214)Chongqing Institute of Engineering 2023 First-class Curriculum Construction Project,“Plant Configuration and Landscape Architecture”(Project No.:KC20230103)。
文摘By analyzing the urgent demand for digital talents in the current landscape industry and the challenges faced by the traditional teaching mode,this study aims to explore a set of teaching methodology reform solutions based on digital technology to improve the quality of teaching and enhance the practical innovation ability of students.The study firstly describes the application of digital technologies such as CAD/BIM,3D modelling and rendering,virtual reality(VR)/augmented reality(AR),and geographic information system(GIS)in the field of landscape architecture.Then,the current teaching status of plant configuration and landscape architecture courses is analyzed,and the advantages and challenges of digital technology applications are identified.On this basis,this study proposes a multi-dimensional reform path and practice plan including the reconstruction of teaching objectives and content,innovation of teaching mode,improvement of teaching strategies and methods,as well as the construction of teaching resources and the reform of teaching evaluation,guided by modern educational theories such as constructivism,collaborative learning and project-based learning(PBL).Finally,this study emphasizes the key roles of faculty construction,optimization of hardware and software environment,and teaching management and institutional guarantee in the reform.
基金supported by the National Science Foundation of China(Grant Nos.42374205 and 41974179)the Specialized Research Fund of the National Space Science Center,Chinese Academy of Sciences(Grant No.E4PD3010)supported by the Specialized Research Fund for State Key Laboratories.
文摘The three-dimensional spectral analysis method was applied to airglow data from September 2023 to August 2024 derivedfrom an OH airglow imager located at the Hejing station (42.79°N, 83.73°E) to study the propagation characteristics of gravity waves(GWs) over Northwest China. We found that obvious seasonal variations occur in the propagation of GWs. In spring, GWs mainlypropagate in the northeast direction. In summer and autumn, GWs mainly propagate in the north direction. However, GWs mainlypropagate in the south direction in winter. The direction of GW propagation in the zonal direction is controlled by the wind-filteringeffect, whereas the north–south meridional direction is mainly determined by the location of the wave source. We found that the averageenergy spectrum exhibits a 10%–20% higher intensity in summer and winter compared with spring and autumn. For the first time, wereport the seasonal variation characteristics of GWs over the inland areas of Northwest China, which is of great significance forunderstanding the regional distribution characteristics of GWs.
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.
