最新刊期
卷 63 ， 期 5 ， 2024
- 摘要：The presence of ghost waves suppresses the low-frequency energy of signal acquired in marine seismic exploration， while deep structures of the earth mainly correspond to the low-frequency signal components， thus， it is of great significance to improve the low-frequency components suppressed by ghost waves for the detection of deep structures. One of the key parameters of ghost wave suppression is the arrival time difference between the ghost wave and the primary reflected wave， and its accuracy directly affects the effect of ghost wave suppression. Due to the influence of factors such as undulating sea surface， rugged seabed， depth change of reflective layer， and distribution of inhomogeneous media， the arrival time difference between the ghost wave and the primary reflected wave can often not be accurately estimated， resulting in the failure to achieve good results in ghost wave suppression. In this paper， based on the characteristics of the deghosting filter， a filter that does not disturb the high frequency and only improves the low frequency is designed to bypass the suppression of the ghost wave and only focus on the energy improvement of the low-frequency signal. The results of model tests show that the waveform processed by the proposed method is morphologically close to the primary reflected waveform without ghost wave interference. Moreover， the lower the dominant frequency of the seismic signal and the smaller the sinking depth of the towing cable， the stronger the energy enhancement effect of this method on the low-frequency signal. A test applied in the deep reflection seismic profile of the South China Sea has also attained good performances.关键词：low-frequency enhancement;ghost wave suppression;deep structures detection;marine seismic exploration
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发布时间：2024-11-07 - 摘要：Altered minerals introduced by water-rock reactions during geothermal energy recovery may play a role in the frictional properties of fault gouges， perhaps inducing earthquakes. Based on the geological conditions of potential geothermal reservoirs in northeastern Shenzhen， this paper considers the critical pore pressure （about 50 MPa） and critical effective normal stress （about 20 MPa）， which may lead to reactivation of the Henggang-Luohu fault zone due to fluid injection into a potential geothermal reservoir at a buried depth of about 2.5 km with the temperature of 150 ℃. Under such hydrothermal conditions （50 MPa fluid pressure and 150 ℃）， thermodynamic calculations suggest that the reaction of Yanshanian granular granite and water， at equilibrium， can produce silica， kaolinite， and chlorite at a mass ratio of 16∶7∶2. Here we report 19 direct shear experiments performed on simulated fault gouges consisting of the binary mixture of silica + granite， kaolinite + granite， and chlorite + granite， and the multivariate mixture of silica + kaolinite + chlorite + granite， to investigate the effects of altered minerals on frictional properties of simulated granite fault gouges. Velocity stepping experiments were conducted on the wet samples with 10% water content at an initial normal stress of 20 MPa under drained conditions at room temperature. On this basis and together with acoustic emission observation and microstructural analysis， we discussed the likely mechanism responsible for the observed behavior. The results show that， for the presence of a single altered mineral， silica has little effect on the friction coefficient， though it contributes to velocity weakening and even stick-slip events. Whereas， clay minerals can significantly decrease the friction coefficient， though they have a contribution to velocity strengthening. For the presence of a mixture of silica + kaolinite + chlorite， clay minerals play a dominant role in controlling frictional properties of the simulated fault gouges： altered minerals can also significantly decrease the friction coefficient and contribute to velocity strengthening. Development of R1 shear planes was observed using microstructural analysis for the simulated granite fault gouges consisting of 0% or 33% of the altered minerals， while the R1 shear plane cannot be observed anymore in the sample consisting of 67% of the altered minerals. The number of acoustic emission events decreases significantly when the content of the altered minerals is 33%~67%. This may indicate a transition in the deformation mechanism from brittle to semi-plastic. Our study suggests that if geothermal energy recovery is carried out in northeastern Shenzhen， the fluid injection pressure should be controlled to avoid the slip of the fault.关键词：geothermal mining;friction characteristics;water-rock reaction;alteration minerals
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发布时间：2024-11-07 - 摘要：Different from the tensile and shear failures，the inelastic compaction of porous rocks is another important performance of rock deformation. Under compressive stress，high-porosity sedimentary rocks form compaction bands with significantly reduced porosity and permeability. This is not only related to the intermediate regime of the brittle-ductile transition of porous rocks but also has important impacts on the engineering application of fluid flow in reservoirs. To explore the influence of confining pressure and the initial pore structure on compaction localization，we establish a finite element model with the complex pore structure of the rock based on the in situ synchrotron CT images of the triaxial experiment of a Leitha limestone sample and conduct elastoplastic numerical simulations under different confining pressures. Our results show that the samples undergo heterogeneous deformation under the confining pressure of 20 to 60 MPa. As the confining pressure increases，the axial local compression inside the sample is restrained，while the radial local compression is promoted. Most of the nodes in the compaction band have the trend of being away from the quasi-uniaxial compression state under high compression stress，which restricts the development of compaction bands.关键词：CT images of rocks;finite element simulation;porous rocks;compaction bands;confining pressure
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发布时间：2024-11-07 - 摘要：Based on realistic engineering geological data in Guangzhou，this study establishes a finite element model for simulating the collapse of the overlying sand stratum after drilling through karst caves roofs.The coupled Euler-Lagrange method（CEL） is employed to simulate the collapse process of the sand stratum. Multiple sets of numerical simulations are conducted using orthogonal experimental design to investigate the influences of different sand stratum thicknesses，cave sizes，and friction angles on the development pattern and to elucidate the mechanism of collapse in the overlying sand stratum. The results indicate that as the thickness of the sandy soil cover layer increases，both the maximum surface displacement and collapse rate of the sand stratum decrease，and the central collapse area becomes noticeably smaller. With an increase in cave size，the collapse range and maximum surface displacement increase. After drilling through karst cave roofs in engineering projects，the vertically adjacent sand near the karst caves undergoes initial instability and failure，with its influence range primarily affected by the thickness of the sand stratum，and the collapse rate mainly influenced by the range of unstable soil. Once the soil in the central collapse area becomes unstable， the surrounding soil is subjected to shear stress and fails，causing displacement towards the center of the karst cave. The amount of soil migration towards the karst cave is mainly influenced by the size of the karst cave， and this portion of the sand exhibits a collapse morphology similar to the angle of repose.关键词：karst collapse;sand stratum;destruction mechanism;influence factors
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发布时间：2024-11-07 - 摘要：In the context of global climate change， flash droughts occur frequently and can have a huge impact on agricultural production and ecosystem functions in the short term. Therefore， it is of great significance to comprehensively and accurately describe the characteristics and trends of drought for drought risk assessment and agricultural disaster reduction in China. This study used long-term land surface model data and reanalysis datasets to analyze the frequency， intensity， duration， and spatiotemporal distribution of flash drought events in China from 1980 to 2022. Two flash drought detection methods， based on evapotranspiration stress ratio and soil moisture were adopted， respectively， and the Mann-Kendall trend analysis method was used to evaluate the development trend of flash drought characteristics in different regions. The results show that：（1） The identified flash drought ranges using the two methods are more consistent in southeast China， yet great differences exist in northwest China. （2） The area with the highest occurrence of flash droughts identified by the evapotranspiration-based method is the Qinghai-Tibet Plateau， while that from the soil moisture-based method is the central region of Sichuan Province. （3） Flash drought occurrences distribute unevenly among seasons， which is the highest in summer， followed by spring and autumn， and the lowest in winter. （4） The average flash drought duration is mostly 6~10 pentads， it is longer in Northwest China identified by the evapotranspiration method， while it is longer in parts of northwestern and central China by the soil moisture method. （5） The areas with high-intensity flash droughts are Northeast China， Northwest China， Tibet Autonomous Region， and Taiwan Province identified by the evapotranspiration method， while it is in the Southern region by the soil moisture method. The two methods conduct distinct results， the suitability for different situations is waiting for further investigations.关键词：flash drought;evapotranspiration;soil moisture;trend;China
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发布时间：2024-11-07 - 摘要：Based on the continuous observation data of turbulence in 2017 from a field observation station in the Pearl River Delta region， the turbulence characteristics of heat flux， CO2 concentration and flux， and the turbulent kinetic energy of hilly shrubs were analyzed. The results show that：（1） Latent heat flux plays a dominant role in the annual surface energy balance in suburban areas， while the opposite is true for the other land surface patterns. （2） The CO2 concentration at the observation point is slightly lower than those at other land surface patterns， and the variation range of CO2 flux is much greater， indicating that the photosynthesis and respiration of hilly shrubs are significantly stronger than that at lower vegetation coverage and density land surface patterns. （3）Turbulent kinetic energy is large during the day-time but small at night， maximum in summer daytime ； the peak occurs slightly earlier in winter than in summer. （4） The variation of dimensionless velocity variance with atmospheric stability is accord the form of
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发布时间：2024-11-07 - 摘要：The mechanism of MaiFuSheng （MFS） on inhibiting Nonalcoholic Fatty Liver Disease （NAFLD） were investigated based on the exploration of chemical compositions， the techniques of network pharmacology and molecular docking， and the validation using NAFLD mice model. The components of MFS were identified through UPLC-Zeno TOF-MS/MS. The Swiss Bioinformatics Research Platform were applied to obtain active components and potential targets of MFS. The DisGeNet and OMIM databases were used to screen disease targets of NAFLD. The intersection between disease targets and potential targets of MFS were obtained from Venn diagram， which were analyzed by constructing cross-target protein-protein interaction （PPI） network. The Gene Ontology （GO） and Kyoto Encyclopedia of Genes and Genomes （KEGG） enrichment were conducted on Metascape database. The molecular docking about core targets and active components of MFS were carried out. Using high-fat diet （HFD）-induced C57BL/6J mice as NAFLD animal model to validate key targets. A total of 130 compounds were recognized， 54 active constituents and 176 potential targets of NAFLD were collected. The molecular docking experiments for the top 10 components with the targets are based on the degree value. We found docking models with the best binding energy for TNF-α with Quercetin，IL-17 with Asiatic acid，and IL-1β with Quercetin. We applied qPCR technique to detect above inflammation and lipid metabolism related indicators. Enrichment analysis demonstrated that MFS protects NAFLD via biological processes such as fatty acid transformation and positive regulation of lipid metabolism， as well as signaling pathways such as AGE-RAGE，HIF-1，and IL-17. Compared to the control groups，the model group's ALT，TG，and LDL-C indicators increased，whereas HDL-C indicators dropped（P<0.05）. MFS and Simvastatin treatment groups significantly reduced body weight，liver weight，and fat weight compared to the model groups（P<0.05）. Higher doses resulted in significant reductions in serum levels and expression of TNF-α，IL-1β，and IL-17（P<0.01）. Compared to the control groups，the MFS treatment groups can minimize liver lipid accumulation by modulating the expression of lipid metabolism-related genes and improving hepatic fat breakdown.关键词：UPLC-Zone TOF-MS/MS;MaiFuSheng;NAFLD;network pharmacology;experimental validation
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发布时间：2024-11-07 - 摘要：To investigate whether PSGL-1 is correlated with the prognosis of cutaneous malignant melanoma. Genetic data of PSGL-1 and cutaneous malignant melanoma were extracted from genome-wide association studies （GWAS） and analyzed using inverse variance weighting， MR-Egger regression， weighted median， weighted mode， and simple mode methods， and sensitivity analyses were performed on the data. Survival information of cutaneous malignant melanoma was extracted from the TCGA database， and grouped according to high and low PSGL-1 expression， survival curves were plotted by the Kaplan-Meier method， and the Log-rank test was used to compare the difference between the two survival periods. Exploring the effects of PSGL-1 on the biological functions of A375 cells through in vitro experiments. The inverse variance weighted method analysis of PSGL-1 on cutaneous malignant melanoma resulted in OR=0.666， 95% CI （0.494-0.899）， P=0.008. The median survival was 44.70 months in the PSGL-1 high expression group and 29.13 months in the PSGL-1 low expression group， P= 0.000 2. PSGL-1 inhibits the migration of A375 cells in vitro. Increased PSGL-1 expression is a protective factor against cutaneous malignant melanoma and is a potential prognostic marker for cutaneous melanoma.关键词：PSGL-1;cutaneous malignant melanoma;Mendelian randomization study;TCGA database
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发布时间：2024-11-07 - 摘要：Under the stress of biological （aphid） and abiotic factors （drought）， whether the application of wood vinegar compound biological agents can increase crop resistance and achieve stable crop production is of great significance for coping with the challenges brought by future climate change to agricultural production. In this study， drought and wood vinegar were used as treatment factors， and the “Glycine max-Aphis Glycines-Harmonia Axyridis” three-level nutrition system was used as the research object， with a total of 18 treatments. Soybean biomass， root-shoot ratio， population dynamics of A.glycines， predation of H.axyridis， developmental duration， and activities of glutathione-S-transferase （GST） and catalase （CAT） in soybean， A.glycines and H. axyridis were measured. The main results are as follows ：（1） Under mild and severe drought stress， soybean biomass （-29.6%，-66.6%） decreased significantly， and root shoot ratio （15.2%，37.5%） increased significantly. When there were only aphids （lack of natural enemies）， spraying wood vinegar liquid phase under mild drought stress significantly increased the biomass of soybean in the group without wood vinegar （16.2%）. Under mild drought， the GST activity of soybean increased significantly （117.5%）， and the GST （46.5%） and CAT （13.3%） activities of soybean increased significantly after spraying wood vinegar. However， the activities of GST （-78.0%）， POD （-63.9%） and CAT （-81.4%） were significantly decreased under severe drought stress. （2） The population of A.glycines （-12.9%，-22.1%） decreased significantly under mild and severe drought stress. Under mild drought stress and severe drought stress， the application of wood vinegar liquid phase significantly reduced the population of soybean aphids without wood vinegar （-16.9%，-20.0%）. The activities of GST （149.6%） and CAT （48.3%） were significantly increased under severe drought stress. Under mild drought stress， the activities of GST （77.8%） and CAT （52.4%） of A.glycines sprayed with wood vinegar increased significantly. （3） Under severe drought stress， the daily predation of H.axyridis adults decreased significantly （-16.6%）， and the daily predation of H.axyridis adults increased significantly after the application of wood vinegar （8.7%）. The developmental duration of H.axyridis larvae under mild drought and severe drought stress was significantly longer than that under normal watering group （4.9%，10.9% ）. The developmental duration （-4.2%，-5.3%） of H.axyridis larvae fed with wood vinegar treatment under mild drought and wood vinegar treatment under severe drought was significantly shortened. The activities of GST （43.2%） and CAT （156.5%） of H.axyridis were significantly increased under severe drought stress.Therefore，drought stress will inhibit the growth and development of soybean， while spraying wood vinegar can promote the growth and development of soybean， improve the drought resistance of soybean， and have a positive effect on the direct control of soybean aphids and the improvement of the control effect of natural enemies on A.glycines.关键词：drought stress;wood vinegar;three-level nutrition system;biological agents;protective enzymes
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发布时间：2024-11-07 - 摘要：Using 4-carboxyl-1-（3-carboxybenzyl） pyridinium chloride （H2LCl） as the organic ligand， a new complex ｛［Cd2（L）2Cl2（H2O）4］·3H2O｝ was self-assembled at room temperature with Cd2+ through ambient temperature volatilization. The structure and properties of the complex 1 were characterized by single crystal X-ray diffraction， Hirshfeld surface and two-dimensional fingerprint， powder X-ray diffraction， thermogravimetric analysis， and solid-state fluorescence. The study showed that the complex crystallized in the monoclinic P21/c space group， with two Cd2+ metal centers connected by fully deprotonated ligands， forming two mirror-symmetrical "S" shaped double-chain structures. The rich intermolecular forces such as H···H and O···H helped the complex form a stable three-dimensional supramolecular structure. Thermogravimetric analysis showed that the complex had a good thermal stability. In addition， room temperature fluorescence testing showed that the complex 1 also had a good fluorescence emission ability.关键词：coordination polymer;crystal structure;Single crystal cultivation;Hirshfeld surface analysis;solid state fluorescence
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发布时间：2024-11-07 - 摘要：A reversible image authentication method based on wavelet-domain prediction error histogram translation is proposed. First， the image to be authenticated performs a Haar wavelet transform. Second， the low-frequency and high-frequency subbands obtained from the transform are separately partitioned into blocks， and an authentication code is generated based on the coefficient values and locations of these blocks. Then， the authentication code is embedded into the blocks using the improved pixel value ordering （IPVO） method， and the image containing the authentication information is reconstructed using the Haar wavelet inverse transform. In the authentication stage， the tampering detection function is realized by extracting the authentication code and generating the authentication code. If the image is not tampered with， the original image can be recovered losslessly. Experimental results show that the method provides more accurate detection results and ensures a certain level of image quality.关键词：image;reversible authentication;fragile watermarking;tamper detection
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发布时间：2024-11-07 - 摘要：According to the control mechanism of surface arc discharge plasma actuation on the flow and combustion of flameholder， the applicability of the phenomenological model of surface arc discharge is verified. And， the effects of different actuation positions and actuation intensities on the flow field structure， fuel atomization， ignition delay and flame stability in the flameholder are systematically analyzed. The results show that different actuation positions have a significant impact on the flow field structure， especially when the actuation energy is effectively concentrated and a strong actuation region is formed， which leads to the expansion of the recirculation zone， which in turn promotes fuel atomization， slows down the ignition delay and increases the average flame temperature. At the same time， with the increase of actuation intensity， the length of the recirculation zone， the mixing efficiency and the combustion efficiency increased linearly.关键词：flameholder;flow;combustion;surface arc charge;plasma actuation
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发布时间：2024-11-07 - 摘要：
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发布时间：2024-11-07 - 摘要：In order to study the sliding characteristics of gravel materials under cyclic shear load， a self-developed multi-functional dynamic shear testing machine was used to apply constant normal stress and horizontal cyclic shear stress with different peak， valley and frequency to the gravel samples， and to monitor the change of shear displacement of the samples over time during loading. The change of shear displacement increment and the energy density corresponding to shear stress during the whole loading period are analyzed. The results show that the characteristics of slip induced by cyclic shear stress are related to its peak value， valley value and frequency. The periodic shear stress will lead to the slip jump of the gravel material， and the condition of the slip jump point is related to the energy density during the loading period. According to the range of energy density， the slip state of the sample can be divided into three regions， the stable region， the transition region and the jump region.关键词：gravel subgrade;periodic shear stress;multi-functional dynamic shear testing machine;slip characteristics;shear displacement;energy density
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发布时间：2024-11-07 - 摘要：This study enhances the compressive performance of polylactic acid（PLA） bio-based materials by adding flax fibers， and explores the effects of silane coupling agent concentration and flax fiber mass fraction on the compressive mechanical properties of PLA/Flax composite materials. Firstly， scanning electron microscopy（SEM） was used to analyze the microstructure of flax fibers treated with silane coupling agents. PLA/Flax composite material samples with different ratios were prepared using melt blending and injection molding methods. The elastic modulus and yield strength of each sample were measured using a 100 kN universal testing machine. Finally， the microstructure of the cross-section of the composite material was analyzed using SEM， revealing the fiber distribution and interface characteristics inside the material. It was found that， when the flax fiber content is 5.25% and treated with a 2% silane coupling agent， the elastic modulus of the composite material reaches a maximum value of 0.63 GPa， which is 24.2% higher than that of pure PLA material. And the yield strength increased to 124.7 MPa， with an increase of 15.6%. At the same time，the flax fiber treated with a 2% silane coupling agent had a tighter interface compatibility with polylactic acid.关键词：biobased composite;flax fiber;silane coupling agent;compressive performance
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发布时间：2024-11-07 - 摘要：It's proposed that a systematic average age of information optimization algorithm that integrates sensor energy supply， data transmission timeliness， and mobile user requirements. Firstly， an unmanned aerial vehicle assisted WSN is used to secure the energy collection and data transmission from the sensors. Secondly， AoI is introduced as a measure to jointly optimize multi-device scheduling， transmit power and UAV trajectories to establish a non-convex optimization problem with the objective of minimizing the average AoI of the sensors. Then， the non-convex problem is transformed into a convex one by means of constraint relaxation， variable substitution and successive convex approximation， and an iterative average AoI minimization algorithm is designed. Finally， the algorithm is verified through simulation， and the results show that the algorithm effectively improves the freshness of the sensor data while satisfying the mobile user experience.关键词：wireless sensor networks;unmanned aerial vehicle;age of information;energy harvesting
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发布时间：2024-11-07 - 摘要：The method of coupling computational fluid dynamics and discrete phase model was used to calculate the erosion rate of defective pipes under different working conditions. The erosion rate and erosion key areas under different working conditions are compared， and the influence mode of defects on erosion is revealed.The results show that：（1）With the increase of lead-bismuth eutectic flow velocity， the erosion area of both defective and intact pipelines expands significantly. However， the maximum erosion rate of defective pipes decreased， and the erosion rate of intact pipes increased slightly. （2）The increase in particle size will cause the erosion area of the defective pipe to shift from the defective location to the inlet straight pipe section； for intact pipelines， the erosion is concentrated near the entrance of the elbow， and the erosion area of both pipelines is significantly expanded.（3）The existence of defects increases the turbulence intensity at the pit location， and the erosion position of the elbow is concentrated in the pit position， and the maximum erosion rate of the pit position increases significantly with the increase of the pit size.关键词：lead-bismuth alloy;particles;concave defects;discrete phase model;CFD-DPM model;erosion rate
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发布时间：2024-11-07 - 摘要：This paper proposes a multi-layer sparse tensor decomposition model based on multidimensional feature sharing（MFS-MSTD）. On the basis of CP（CANDECOMP/PARAFAC） decomposition， this model applies low rank regularization to the spatiotemporal factor matrix. The mechanism of sharing a low rank factor matrix is adopted to express the complementarity between multi-source traffic data， and the gradient update of the factor matrix can be completed in non-random missing or segment level missing scenarios. A real experment results show that in the scenario of non-random missing speed data， MFS-MSTD reduces the RMSE， MAE， and MAPE by an average of 17%， 21%， and 18% compared to the baseline method； in the scenario of non-random missing traffic data， RMSE， MAE， and MAPE decreased by an average of 52%， 54%， and 33%. In the face of more complex road segment missing scenarios， the imputation performance of MFS-MSTD is superior to the baseline models TGMC-S and MTNTF， and it can well fit the trend of traffic volume changes in unobserved road segments.关键词：traffic data imputation;multi-source traffic data;sharing factor matrix;CP decomposition
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发布时间：2024-11-07 - 摘要：The existence of radial symmetric solutions of a nonlinear fourth order elliptic boundary value problem is discussed. Under the nonlinearity satisfies some inequality conditions， the existence and uniqueness results of radial symmetric solutions are obtained by applying the Leray-Schauder fixed point theorem and the technique of prior estimates.关键词：fourth order elliptic boundary value problem;radial symmetric solution;existence and uniqueness;Leray-Schauder fixed point theorem
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发布时间：2024-11-07
Research articles
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