最新刊期
卷 63 ， 期 4 ， 2024
- 摘要：Under the backdrop of global warming， the frequency of heatwave events has been increasing， adversely affecting the living environment and human health. Existing studies suggest that both natural and socio-economic factors influence the intensity of heatwave events. Therefore， it is particularly important to consider a comprehensive set of natural， social， and economic indicators to assess resistance to heatwaves. This study selects indicators related to the three aforementioned aspects through factor analysis concerning the districts and counties of Guangdong Province. Three common factors are extracted： individual resistance factor， public resistance factor， and natural resistance factor， which have a cumulative contribution rate reaching 90.029% and can accurately reflect the resistance capacity to heatwave events at the county scale. The results show a significant imbalance in heatwave resistance within Guangdong Province，with districts having strong resistance concentrated in the Pearl River Delta region. Based on the factor scores， the districts and counties in Guangdong Province can be divided into five categories： vulnerable resistance zone， individual resistance enhancement zone， public resistance enhancement zone， natural resistance enhancement zone， and strong resistance zone. Most districts and counties have both strengths and weaknesses in their resistance to heatwaves. The study provides specific suggestions for different categories of districts and counties， hoping to offer a scientific basis for mitigating the impacts of heatwave events.关键词：factor analysis;county level scale;heat wave resistance;multisource data
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发布时间：2024-09-29 - 摘要：Mid to long-term precipitation forecasting has always been a hot topic in hydro-meteorological research，with the issue of low accuracy and reliability needing urgent solutions. This study focuses on the Dongjiang Basin and evaluates the prediction accuracy and stability of CFSv2 model products at the monthly scale using the anomaly coefficient of correlation （ACC），normalized root mean square error （NRMSE），mean absolute error （MAE），and the multi-model stability index （MSI）. Two methods，namely the CFSv2 model precipitation forecast and the machine learning model forecast combined with CFSv2 model predictors，are employed to predict future precipitation. The results show that under different lead times，the CFSv2 model precipitation forecast exhibits a high correlation with observed precipitation，performing better during the dry season compared to the flood season. However，there is significant variability in precipitation forecasts and poor model stability with changes in the initial time. Combining CFSv2 model predictors with machine learning models improves the forecast stability，reducing the MSI from 0.45 to 0.25 and effectively reducing the randomness in forecasts caused by changes in the initial time. The findings contribute to providing a new approach for mid to long-term precipitation forecasting and offer decision-making support for mid to long-term hydrological forecasting and water resource management.关键词：CFSv2;mid to long-term forecast;machine learning;product evaluation
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发布时间：2024-09-29 - 摘要：The north part of Hainan Province has widely distributed，abundant basaltic rocks providing a great potential for carbon geological sequestration via mineralization. Engineering practice of carbon sequestration in subsurface basalt requests to understanding of the mechanical properties of basalt at real-time temperature. In this study，Brazilian splitting and uniaxial compression experiments were performed on late Cenozoic basalt samples （mainly minerals including Augite，Al-rich， and Anorthite） collected from northern Hainan Province under real-time temperature conditions of 25-250 ℃，to investigate the effects of temperature on the strength and failure characteristics of the basalt samples. The Brazilian splitting tests show that the tensile strength of the basalt samples reduced from ~13 MPa at room temperature to ~8 MPa at 50 ℃，and finally to ~7 MPa at 250 ℃，accompanied by a dominant fracture surface. The uniaxial compression experiments determine the Young's modulus and Poisson's ratio of 31.0-175.3 GPa and 0.13-0.48，respectively，having the maximum values at temperatures of 100-150 ℃. The compressive strength of 77.5-159.5 MPa decreases slightly with temperature but is associated with larger discreteness. The basalt samples upon uniaxial compression exhibited shear failure along a single plane at temperatures of 25-100 ℃，while shear failures along multi-planes at temperatures of 150-250 ℃. This may be attributed to the increase of the proportion of tensile microcracks upon temperature rise during the microcracking process. Combining the results from both experiments，the tensile strength reduction and the scattered uniaxial compression mechanical parameters observed at temperatures of 25-250 ℃ are likely dominated by the thermally activated rate process，rather than the thermal damage mechanism. From a perspective of temperature-dependent mechanical properties of the collected basalt samples，this study implies that deep burial depth （higher temperature） favors the carbonation reaction of basalt and CO2，as the reduction of tensile strength may accelerate the fracturing process to enhance the reactive surface between basalt and CO2-rich fluids. Nevertheless，complex deformation and failure mechanisms caused by temperature during in-situ subsurface carbon sequestration in basalt also need serious considerations in future studies.关键词：Hainan basalt;carbon geological sequestration;failure modes;Brazilian test;tensile strength
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发布时间：2024-09-29 - 摘要：The intrinsic energy exchange exists between the shallow ground temperature and near-surface air temperature.As time progresses， surface temperature changes are propagated downwards and superimposed onto the steady-state geothermal field.Therefore， it is possible to reconstruct the history of ground surface temperature changes using the current subsurface temperature profile. To assess the combined effect of global warming and urbanization on the subsurface temperature of Guangzhou， this paper collected temperature data from Guangzhou station during 1958-2022 and conducted regression analysis and anomaly analysis. Meanwhile， the temperature-depth （T-Z） profiles of 16 observation boreholes in Guangzhou were obtained through field measurements. By conducting regression analysis on the lower section of the temperature profile， the geothermal gradient of the area and the depth of deviation from the constant geothermal gradient were determined. Finally，the onset time and magnitude of warming were obtained by combining temperature data， and the theoretical curves of the surface warming profile in Guangzhou were derived using the analytical solution equation. The results show that the warming rate of air temperature in Guangzhou from 1958 to 2022 is 0.33 ℃ per decade， with the onset time of warming being 1987， and the magnitude of warming being 2.6 ℃.The observed geothermal gradient in Guangzhou is 0.036 ℃/m， and the depth of deviation from the constant geothermal gradient is 54.8 m， essentially consistent with the analytically calculated depth of 57.6 m. The study finds that the earlier the start time of urbanization-induced surface warming， the greater the depth of deviation of subsurface temperature from the constant geothermal gradient， indicating the depth of deviation can be used to describe the process of urbanization.关键词：global warming;urbanization;air temperature;ground temperature;Guangzhou
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发布时间：2024-09-29 - 摘要：To investigate the influence of polyaluminum chloride on sludge dewatering performance and the mechanism of combining different dewatering methods to improve sludge dewatering performance， this paper carried out self-weight dehydration， centrifugal dehydration， and dialysis dehydration tests. It is found that 8% of polyaluminum chloride pretreatment combined with dialysis dehydration has the best effect. The residual moisture content of the optimally pretreated sludge reduces to 36.2% by dehydration， and its gravity water， enclosed water， enclosed water， and bound water are 81.2%， 10.2%， 7.3%， and 1.3%， respectively. After the sludge is pretreated with polyaluminum chloride， the spacing between the sludge particles is narrowed， the pores are reduced， there are no obvious large pores， and the structures tend to be uniform and more compact. The porosity is reduced to as low as 0.29 by using the optimal amount of polyaluminum chloride pretreatment combined with dialysis dehydration. It is speculated that polyaluminum chloride condenses the sludge into small and dense sludge particles， and this skeleton structure is conducive to the transfer of dialysis force； while free water is discharged continuously， the sludge structure continues to be closer， and promoting the transfer of dialysis force in the sludge.关键词：polyaluminum chloride;sludge;different dehydration methods;dehydration mechanism
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发布时间：2024-09-29 - 摘要：To analyze the influence of complex terrain and buildings on the wind field of Zhuhai Airport and whether they will induce low-level wind shear,the Computational Fluid Dynamics (CFD) code FLUENT was used to simulate the wind environment around the terrain and buildings of Zhuhai Airport,and the prone airspace of low-level wind shear at the airport under the background of north(N),north-northwest(NNW) and northeast(NE) wind were analyzed. The results show that: 1) The wind speed fluctuations caused by terrain and buildings at the airport runway under the three wind directions all appear below the height of 500 m,and all of them mainly appear along the runway. 2) When the wind direction is N or NNW,the wind shear appears at the height of 100-500 m and is mainly induced by the terrain. 3) When the wind direction is N,the maximum probability of low-level wind shear is outside the southern end of the runway (in the area of 0.5-1.4 km from the southern end) and the second is near the southern end (0.2-1.5 km from the southern end within the runway); when the wind direction is NNW,the maximum probability of low-level wind shear is near the south end of the runway (0.5 km outward from the port to 1.1 km inward from the port) and the second is near the midpoint of the runway about 0.3 km. 4) When the wind direction is NE,the probability of low-level wind shear on the airport runway is low. The research results provide a basis for the detection and early warning of low-level wind shear at Zhuhai Airport to prevent wind shear and have significance for airport location and aviation safety meteorological risk assessment in the future.关键词：low-level wind shear;CFD simulation;complex terrain;buildings;airport runway
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发布时间：2024-09-29 - 摘要：Exploring the overall characteristics and internal sub-structure of intercity land public passenger transport connection patterns in the Pearl River Delta is of great practical and contemporary significance for improving the resilience of the transport network， rationally planning the metropolitan area， and realizing sustainable and coordinative development. Based on the intercity land public passenger transport data， this paper analyzed the spatial pattern and structural characteristics of the connections between cities in the Pearl River Delta by using the contact index and social network analysis method. The results show that： 1） The trend of passenger flow varies， but the cities with the first degree of contact and the high intensity of contact are stable. The direction of passenger flow in different years changed slightly， while the pattern of the priority centered on Guangzhou and Shenzhen is unchanged. The cities with the highest contact intensity are concentrated in Guangzhou， Shenzhen， and Dongguan， which is consistent with the comprehensive economic strength of the city. 2） The cities in the Pearl River Delta show the inner and outer circle connection structure of the core-edge. The inner core positions of Guangzhou， Shenzhen， and Dongguan have remained unchanged. The urban traffic links within the marginal areas have been strengthened. 3） The structure of Shenzhen-Dongguan-Huizhou of the eastern Pearl River Delta is stable， in line with the metropolitan planning， whereas the structure of other subgroups varies. In the middle of the Pearl River Delta， there is a big difference between the planning of the central Guangzhou-Foshan-Zhaoqing area and the subgroup. It is necessary to strengthen the passenger connection between the three cities so that it can truly form a subgroup with a strong connection. Except for Guangzhou， the three subgroups are relatively independent with fewer passenger transport connections.关键词：traffic connection;land public passenger transport;social network analysis;spatial pattern;substructure characteristics
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发布时间：2024-09-29 - 摘要：Guanxi pomelo （Citrus Grandis cv ‘Guanximiyou’） is popular for its sweet and colorful juice sacs. The pigments in juice sacs are mainly carotenoids， whose composition and concentration directly affect the quality of fruits. Characterization of the carotenoid components in juice sacs and their differences under different nutrient management might provide scientific basis for improving fruit quality through nutrient management. In the study， liquid chromatography-tandem mass spectrometry （LC-MS/MS） was used to analyze the carotenoid components in juice sacs； and the effects of different nutrient management on carotenoids were compared between the usage of chemical （CF） and organic （OF） fertilizations. The results showed that the juice sacs contained 23 carotenoids， among them， 5 and 18 belonged to carotene and lutein， respectively. The carotenoid in juice sacs was mainly carotene with the concentration as （346.27±69.39） μg/g. Lycopene is the major component of carotenes， which concentration was （332.27±75.05） μg/g and proportion was 95.67%. In addition， fertilization management significantly affected the concentration of carotenoids. Compared with CF， the concentration of lycopene and （E/Z）-phytoene in OF increased 8.40% and 16.48%， respectively， indicating that nutrient management could affect the pigment in juice sacs of Guanxi pomelo， and thereby might provide references for further regulating fruit quality through nutrient management.关键词：pomelo（Citrus grandis）;quality;carotenoids;lycopene
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发布时间：2024-09-29 - 摘要：A finite element model （FEM） is established based on ANSYS-APDL and multi-span continuous beam theory for a new novel segmented-design fuel rod （NSDFR）. The FEM equivalent the fuel rod to a BEAM 4 element， the dimple and spring to a COMBIN 14 element. Subsequently， based on the mode data obtained from ANSYS-APDL and semi-empirical equations， the characteristics of turbulent excitation， flow instability， and vortex shedding are systematically studied，as soon as compared with traditional structures. Finally， the impact of grid failure on turbulent excitation， flow instability， and vortex shedding of fuel rods is evaluated.关键词：NSDFR;flow-induced vibration;grid failure;ANSYS-APDL
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发布时间：2024-09-29 - 摘要：The open-source software Nek5000， based on the spectral element method， was used to conduct direct numerical simulation （DNS） of the pressure vessel inset pipe. A simplified 1/3 scale pressure vessel with a main pipe Re of 63 700， a downcomer section Re of 14 014， and a flowing medium of sodium iodide solution were used for the simulations. Turbulent statistics were conducted on common physical quantities， leading to the construction of a highly accurate turbulent flow database. Fluent was used to conduct an adaptive assessment of common wall functions and turbulent models， with assessment criteria based on velocity， turbulent kinetic energy， and turbulent viscosity. The findings indicate that the Stress-ω model is optimal for the rising section， whereas the Standard k-ω model is preferable for the downcomer section.关键词：pressure vessel;jet;DNS;turbulence model;wall function;assessment
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发布时间：2024-09-29 - 摘要：This paper proposed a collision avoidance maneuver strategy using a continuous thrust phasing mechanism for spacecraft equipped with low-thrust propulsion systems， such as electric propulsion. Firstly， the spacecraft collision probability based on the uncertainty of the initial state using chaotic polynomial expansion was analyzed， which served as an evaluation metric for collision avoidance strategies. Subsequently， an analytical solution for orbital maneuver applicable to low-thrust propulsion was derived. This analytical solution introduces a novel collision avoidance method， which involved fine-tuning the spacecraft's orbital phase to reduce collision probability. Besides， this method could swiftly restore the original orbital phase post-maneuver. Numerical simulations demonstrate that the proposed collision avoidance strategy effectively reduced collision probability within a short time. The simulations also revealed the relation between collision avoidance time， fuel consumption， and thrust acceleration.关键词：collision avoidance strategy;collision probability;low-thrust propulsion system;analytical control law
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发布时间：2024-09-29 - 摘要：An example of using the sparse representation algorithm to obtain a basis function dictionary for synthetic-aperture radar （SAR） scenes. The comparative of sparse representation of images before and after filtering shows that speckle noise has an impact on the dictionary results of sparse representation of SAR scenes. Select specific SAR image data from Pujiang No.2， ALOS2， and SIR-C， it is discussed that the effects of optimization algorithm， sample content， dataset size， radar resolution， polarization method， and band on dictionary results by setting single factor conditions. The results show that：（1） The dictionary learned from sparse representation of SAR scenes is related to radar band， resolution and polarization mode， and is independent of sample contents， datasets size， and optimization algorithms. （2）C-band can better reflect the sparsity of SAR scenes than L band. （3）The downsampling dataset can better reflect the sparsity of SAR scenes. （4）The dictionaries learned from HH and VV polarized images have more essential features.关键词：SAR;sparse representation;base function dictionary;speckle noise;polarization
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发布时间：2024-09-29 - 摘要：This paper proposes a novel approach that utilizes ontology technology and semantic logic representation， which can construct a standardized knowledge repository in the form of a knowledge graph （KG） for autonomous transportation system （ATS）. In addition， an architecture-adaptive transformation schema， to facilitate the automatic evolution of specific architectures across generations， grounded in evolutionary analysis is designed in accordance with inferring the system's evolutionary trajectory. To validate the schema， a fair and comprehensive assessment involving rational， efficient， and effective is achieved based on an open-source KG of ATS. The summarized results can， experimentally， showcase the potential of the proposed approach to meet the evolving requirements of transportation system has got， and continuously get transformed to ATS.关键词：autonomous transportation system;evolution analysis;knowledge graph;ontology;semantic web
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发布时间：2024-09-29 - 摘要：A channel estimation algorithm based on parallel factor（PARAFAC） decomposition is proposed. Firstly， the channel is modeled according to the inherent sparse characteristics of the millimeter-wave channel. Then， the signal matrix is constructed into a three-dimensional tensor by using the characteristics of the block fading channel， and the tensor is decomposed by the parallel factorization algorithm. Then， the compressed sensing（CS） theory is used to transform the decomposed matrix into a sparse signal recovery problem. Finally， the bilinear alternating least squares（NBALS） algorithm is improved to solve the channel. The simulation shows that compared with the existing BALS algorithm， wBALS algorithm， and LSKRF algorithm， the proposed algorithm improves the estimation accuracy.关键词：IRS;millimeter wave communication;channel estimation;tensor;parallel factorization
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发布时间：2024-09-29 - 摘要：This study completed a series of laboratory tests to obtain all HSS model parameters of water-rich soft soil in Zhuhai area， and analyzed the proportional relationship between the modulus of key parameters
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发布时间：2024-09-29 - 摘要：Molecular dynamics （MD） simulations were conducted in this research to investigate the interface system between a binary carbonate molten salt and a nickel oxide slab. In this study， we elucidate the trends of interface thermal resistance， thermal conductivity， and viscosity with increasing temperature by analyzing the density distribution and radial distribution functions （RDF）. We also compare the differences in properties between single-phase molten salt and molten salt near the slab. Simulation results show that the increase in temperature results in an expansion of ion distance and weakening of their Van Der Waals interactions and Coulombic interactions， making energy transition more difficult. Consequently， there is a decrease in interface thermal resistance and thermal conductivity. Meanwhile， the viscosity decreases due to weaker interactions among ions as well as increased energy and movement tendencies.关键词：smolten carbonate fuel cell;molten salt;interface;molecular dynamic;thermophysical properties
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发布时间：2024-09-29 - 摘要：Photonic crystal（PC） are artificial electromagnetic material realized by analogy with crystal structures，known as photonic semiconductors. The experimental optical paths of two-dimensional simple triangular PC， two-dimensional complex square PC， and three-dimensional simple PC have been designed by using multi-beam holographic interferometric method in this paper. The multi-scene virtual simulation experimental platform is developed by using computer tools such as Unity， C#， and 3dsMax comprehensively. This virtual platform can realize the generation， propagation， and regeneration of virtual laser， as well as the automatic reflection， splitting and other functions of the virtual laser beam. Besides， it also supports the arbitrary design of optical path for forming various PC. Such virtual experimental platform possesses the advantages of figurative， intuitive， convenient control， rich patterns， low cost， and strong openness.关键词：photonic crystal;multi-scene;holographic fabrication;virtual simulation
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发布时间：2024-09-29 - 摘要：The stochastic differential portfolio game between two competing investors with undertaking of the relative performance concerns is studied. Assume that the financial market is composed of a risk-free asset and a risky asset whose price process is described by the classical Heston model. Under the framework of Nash equilibrium theory， a non-zero-sum stochastic differential portfolio game model is constructed which maximizes the expected utility of the terminal relative performance. Utilizing the dynamic programming principle， explicit expressions of the value functions and Nash equilibrium for portfolio decisions are obtained under the representative case the CRRA utility. Finally， some numerical examples are performed to illustrate the influence of model parameters on the Nash equilibrium together with some economic interpretations. Results show that， the best response of each investor to the competition is to mimic the strategy of its opponent. Consequently， the portfolio decision of an investor with the relative performance concern is more risky than that without the relative performance concern， and thus increases the systemic risk in financial markets. Moreover， model uncertainty will cause an risk-averse investor to adopt more conservative investment strategies than an ambiguity-neutral investor， which is reflected in the reduction of the amount invested in the risky asset.关键词：portfolio game;Nash equilibrium;CRRA utility;relative performance;model uncertainty
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发布时间：2024-09-29
Research articles
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