最新刊期
卷 57 ， 期 5 ， 2018
- 摘要：The coherent leading modes of precipitation variation over the South China Sea and surrounding area in May and June and their mechanisms statistically were studied, based on the observed data in recent thirty-eight years. The first coherent leading mode shows the similar spatial patterns of precipitation anomalies in May and June. The anomalies in the Indochina Peninsula, the South China Sea and the Philippine Sea are in-phase, which are out of phase with the anomalies in southern China. The first principle component is dominant on interannual time scale. This first leading mode is closely attributed to ENSO events occurred in the previous year. The cold (warm) ENSO events force the persistent anomalous cyclone(anti-cyclone) over the South China Sea and the Philippine Sea in May to June, which eventually leads to a persistent anomalous precipitation over the South China Sea and surrounding areas. The second coherent mode exhibits a rough anti-phase spatial distribution in May and in June. The anomalies in the east part of China are anti-phase to those in the central South China Sea and the Philippine Sea. The second principle component is dominant on interdecadal time scale. This mode is mainly attributed to the advanced interdecadal change of the South China Sea summer monsoon onset affected strongly by the interdecadal change of evolution of low frequent intraseasonal oscillation.关键词：anomalous mode of precipitation;mechanisms;South China Sea and surrounding areas;late spring and early summer
- 151
- |
- 301
- |
- 0
发布时间：2023-12-11 - 摘要：The characteristics of diurnal variations in amount，frequency and intensity of hourly heavy precipitation in flood seasons, including the first and second flood seasons, and the spatial distribution were studied based on the hourly precipitation data from 32 meteorological observational stations in Guangdong during 1961-2014. The results show that the peak of hourly heavy precipitation amount and frequency occurred at 16:00, the second peak occurred at 08:00, but the intensity diurnal variations of heavy precipitation were not obvious. There were regional differences at the peak of hourly heavy precipitation amount and frequency in flood seasons. The peak occurred in the morning (06:00 to 09:00) and at noon (10:00 to 13:00) in southern coastal areas, in the afternoon (14:00 to 20:00) in Leizhou Peninsula and the rest of Guangdong. The peak of hourly heavy precipitation intensity occurred on day and night. There were three high-value centers of the peaking amplitudes of hourly heavy precipitation amount during the first and second flood seasons, located in western Lauding, eastern Wuhua, northern Nanxiong and Lianpin. The peaking amplitudes of hourly heavy precipitation frequency showed increasing trend from coastal areas to inland, but there was little regional difference of the peaking amplitudes of hourly heavy precipitation intensity.关键词：hourly heavy precipitation;diurnal variation;flood season;Guangdong
- 115
- |
- 185
- |
- 0
发布时间：2023-12-11 - 摘要：In order to understand the formation mechanisms of carbonated springs along Heyuan fault zone, Guangdong Province, comprehensively figure out their formation processes, and provide basic knowleges for their development and management, five groups of carbonated water samples and 18 groups noncarbonated water samples were collected along the Heyuan fault zone, Guangdong Province, and their hydrochemical characteristics, δD、δ18O、14C、δ13C and3He/4He isotopes were analyzed. The results showed that Na-Ca-HCO3is the main water chemistry type for the carbonated spring, and δD and δ18O isotopes are between -43.32‰~-41.72‰ and -7.06‰~-6.55‰, respectively. All the dots of groundwater smaples are located close to the atmospheric precipitation line, indicating that carbonated springs receive atmospheric precipitation recharging, and recharge elevation is between 1 000 m~1 300 m. The age of carbonated spring is calculated at 21~26 ka through the14C method dating and the revised δ13C age correction model. The range of δ13C of carbonated springs is between -1‰ and 2‰, with the R/Ra (the ratio of3He/4He in samples to3He/4He in atmosphere) ratio between 0 and 2.5, which indicates that CO2gas in carbonated springs in the Heyuan fault zone is the source of mixing between mantle source and metamorphism, and is mainly based on metamorphism.关键词：fault zone;carbonated spring;hydrochemical;environmental isotopes
- 184
- |
- 200
- |
- 0
发布时间：2023-12-11 - 摘要：Daily and hourly environmental and meteorological observation data in Huizhou of Guangdong Province during 2013-2016 were used to analyze the characteristics of ozone pollution in summer and autumn, and the ozone pollution process on July 12-13, 2013 was analyzed. The results show that: ① Ozone pollution appeared in all seasons with the average number of days of 12.5 in summer and autumn accounting for 73.5% of the annual ozone pollution days. The frequency of occurrence of westerly wind (WSW-W-WNW-NW) in summer and autumn during ozone pollution days and ozone moderate pollution days were 44.9% and 74.4%, respectively. In summer and autumn, most of the ozone pollution days occurred in weather conditions with hot and sunny weather, abundant sunshine and westerly wind. The climate characteristics in summer and autumn make a high-risk period for ozone pollution. ② The ozone pollution process on July 12-13, 2013 was mainly affected by the sinking of the “Su Li” and the westerly airflow. Hot and sunny weather and abundant sunshine were beneficial to ozone generation, the westerly winds on the ground and low-altitude make Huizhou in the downwind direction of the Pearl River Delta urban group, which led to regional pollution transport, while the vertical downdraft was not beneficial to pollutant transport and diffusion.关键词：ozone pollution;summer and autumn;meteorological conditions;Huizhou
- 145
- |
- 217
- |
- 0
发布时间：2023-12-11 - 摘要：Urban heat island (UHI) has been mostly reported as the consequence of accelerated urbanization and industrialization. UHI can be obviously regulated by the cooling island effect of urban green spaces. Thus, growing attention has been paid to understanding the cooling regulation mechanism of urban green spaces. Land surface temperature (LST), vegetation cover, normalized difference moisture index (NDMI), reduced simple ratio (RSR), and urban green spaces in Guangzhou were retrieved using Landsat8 images in autumn and winter. This study focused on the correlation relationships between LST and land surface attributes (such as vegetation cover, NDVI, and RSR) in autumn and winter, and also paid much attention to know how LST was affected by urban green spaces as urban green spaces varied in area and parameter and land surface attributes. The results showed that both UHI magnitude and area are much higher in autumn than in winter. Compared with winter, there was better correlation relationship between land surface attributes and LST in autumn, indicating that better cooling effect could be existed in autumn with higher temperature. However, logarithmic function relationship was existed between LST and RSR. It was indicated that cooling effect of vegetation could be at “saturation” as RSR used, when vegetation cover increased. LST exponentially decreased with buffer distance increased. Cooling effect of urban green spaces was gradually limited, when buffer distance continued to be increased as buffer distance is greater than 300 meters. Cooling effect of urban green spaces was much stronger in autumn than in winter. Furthermore, LST was also negatively correlated with both the area and parameter of urban green spaces and higher correlation coefficient occurred in winter. There was significant correlation relationship between internal LST and land surface attributes of urban green spaces and higher correlation coefficient occurred in autumn. LST difference between internal and external green spaces was not significantly correlated with vegetation cover and RSR in both autumn and winter, except for NDMI in autumn. LST was not directly affected by vegetation cover and RSR. Generally, cooling effect of urban green spaces was obviously better in autumn.关键词：urban heat island;urban green space;vegetation cover;normalized difference moisture index;reduced simple ratio.
- 199
- |
- 165
- |
- 0
发布时间：2023-12-11 - 摘要：Aiming at the problem of transition in fluid dynamics, a empirical correlation based B-C transition model is proposed. This transition model does not change the number of transport equations, and overcomes the disadvantage that the transition model containing the transport equation will change the number of equations in the calculation process. B-C transition model uses an intermittency function to multiply the production term of the SA turbulence model to implement the transition simulation. The transition model was calibrated by the experimental data of the zero pressure gradient flat plate. Based on the calibrated transition model, the flow over the twodimensional low speed airfoil was investigated. Comparison between the calculated results and the experiment data indicates that the B-C transition model after calibration can more accurately simulate the transition location of the flat plate case; in the moderately high and low Reynolds number range, the B-C transition model can calculate the aerodynamic coefficients more accurately at moderately high angle of attack.关键词：transition model;empirical correlation;calibration
- 184
- |
- 144
- |
- 0
发布时间：2023-12-11 - 摘要：Taking Shenzhen soft soil as research object, the pore structure characteristic parameters were obtained by mercury intrusion porosimetry, and the relationship between compression modulus of soft soil under loading and the pore structure characteristics such as pore volume, pore size and pore connectivity was studied, then the mechanism of compression modulus changing with pore structure of soft soil under loading was discussed. The research shows that a negative power function relation exists between compression modulus of soft soil under loading and the pore structure characteristic parameters including total pore volume content, average pore size and pore connectivity value. And the change process of compression modulus of soft soil under loading with the pore structure might be divided the two stages.关键词：soft soil;compression modulus;pore structure;mercury intrusion porosimetry
- 139
- |
- 256
- |
- 0
发布时间：2023-12-11 - 摘要：Using the improved AHP method and fuzzy comprehensive evaluation, this paper establishes an inter-city transit satisfaction evaluation system from five aspects including economy, reliability, convenience, comfort and accessibility on the basis of analyzing the satisfaction and traveler characteristics. And then combining Guangzhou and Foshan inter-city transit travel survey data, to calculate weights of index layer and satisfaction score, and create four paradigm analysis model. The results show that the comfort and accessibility have great influence on inter-city transit satisfaction. The total score of travel satisfaction of Guangzhou-Foshan inter-city transit is 63.8, which is between “average” and “satisfied”, and the scores of accessibility and economy are higher.关键词：inter-city transit;improved AHP method;fuzzy comprehensive evaluation;satisfaction
- 160
- |
- 192
- |
- 0
发布时间：2023-12-11 - 摘要：This paper was intended to investigate the influence of zonal multiple blasting of the subsequently excavated tunnel on its surrounding rock and the antecedently excavated tunnel when a twin-tube eight-lane tunnel with a large cross section was excavated by the double sidewall heading method. To this end, the study took Niuzhaishan Tunnel, a twin-tube eight-lane road tunnel with a small clear distance in Pingtan Comprehensive Pilot Zone, as an example, established a twin-tube tunnel model in LS-DYNA, and carried out analysis based on field measurements of vibration velocity. The results were as follows: ① The maximum vibration velocity significantly attenuated as the distance between the blast center and the monitoring site increased. ② Among all the factors that influenced the structure of the antecedent tunnel during the explosion of the subsequent tunnel, the distance between the explosive source and the antecedent tunnel exerted the greatest influence, followed by charge quantity; the ratio of the maximum vibration velocity of the tunnel wall facing the blasting site to that of the tunnel wall facing away from the blasting site was 12.5; such ratio of the tunnel wall at waist height to the tunnel wall at the bottom was 2.1; by the same token, such ratio of the tunnel wall at shoulder height to the tunnel wall at the bottom was 1.9. ③ During the excavation process using the double sidewall heading method, Zone I made the most impact on the antecedent tunnel, due to its shorter distance to the antecedent tunnel and its fewest number of free faces. Thus, Zone I could be made the controlled case to monitor the blast-induced vibration that the antecedent tunnel underwent.关键词：large span tunnel;two side-wall pilot tunnel method;tunnel with small clear spacing;many times of blasting;numerical analysis
- 141
- |
- 163
- |
- 0
发布时间：2023-12-11 - 摘要：Key words:urban traffic,guide signs,deployment model,ring radial road network,guidance information关键词：urban traffic;guide signs;deployment model;ring radial road network;guidance information
- 215
- |
- 174
- |
- 0
发布时间：2023-12-11 - 摘要：The study investigated the mechanism of optical isomerism of two stable conformations of lysine catalyzed by hydroxide ion groupwater clusters and the damage induced by hydroxy radicals in water environment of two conformations of valine molecules by using MP2/6-311++G(2df, pd)∥B3LYP/6-31+G(d, p) dualtheory. The result of reaction channels showed that there are two channels a and b in the optical isomer reaction of lysine. In channel a, the substrate was formed by hydrogen bonds of hydroxide ionwater clusters withα-H and N of amino groups; hydroxide ion abstractedα-H, and thenα-C abstracted the hydrogen of two water clusters at the other side. And in channel b, the substrate was formed by hydrogen bonds of hydroxide ion-water clusters withα-H and O of carbonyl groups; hydroxide ion abstractedα-H, and thenα-C abstracted the hydrogen of two water clusters at the other side. Lysine can be damaged by hydroxy radicals abstracting hydrogen in channel b. The potential energy surface calculation showed that the dominant optical isomerism reaction channels are channel b both in conformation 1(monohydrogen bond between amino- and carboxyl-group) and 2(dual-hydrogen bond between amino- and carboxyl-group), and the energy barriers of rate-limiting steps are 49.94, 60.41 kJ/mol, relatively. So the damage by hydroxy radical of conformation 1 and conformation 2 in channel b was low or non-barrier exothermic reactions.关键词：lysine;density functional theory;transition state;perturbation theory;Gibbs free energy;hydroxide ion;hydroxy radical;optical isomers;damage
- 152
- |
- 200
- |
- 0
发布时间：2023-12-11 - 摘要：Diospyros penghuaea new species of Ebenaceae endemic in Danxiashan mountain, Guangdong, China, is here described and illustrated. Morphologically, the new species is most similar toD. cathayensisandD.rhombifoliabut it differs in its evergreen shrub or small tree, nonspiny branchlets. The leaf shape and seed size are also clearly distinguished fromD. cathayensisandD.rhombifolia.This new species is in honor of Prof. Peng Hua, School of Geography and Planning, Sun Yat-sen University, who made a significant contribution to our knowledge of Danxia Landform research.
- 514
- |
- 205
- |
- 0
发布时间：2023-12-11 - 摘要：Diversity of fish species in eight Mangrove areas in Guangdong was investigated between 2016 and 2017 in four seasons. Eighty-three species were found, belonging to 13 orders and 34 families. There were differences in dominant species of the fish captured in the eight Mangrove areas, mainly small fish or baby fish. Significant differences existed not only in fish tails, catches and Shannon-Wiener diversity index, but also in Pielou evenness index and Margalef richness index. A cluster analysis was conducted on the catches in different groups: the group of Chengraowei, Chenghai and Huren Village, Raoping in the eastern part of Guangdong, the group of Futian, Shenzhen and Daya Bay, Huizhou in the Pearl River Delta, the group of Shuidong Bay, Mao ming and Guanghai Bay, Jiangmen in the west of Guangdong, and the group of Gaoqiao, Lianjiang and Qi Ao Islang, Zhuhai. The Sequence analysis supported the results of cluster analysis. The correlation analysis showed that the fish tails, catches and the species numbers as well as Shannon-Wiener diversity index and Margalef richness index had significant correlations with the area of mangrove forests, the local mangrove plants and water temperature.关键词：Guangdong;mangrove;fish species diversity
- 226
- |
- 172
- |
- 0
发布时间：2023-12-11 - 摘要：Pregnane X receptor (PXR) transcriptional factor is one of the nuclear receptors family members, which plays a crucial role in the process of the transformation and metabolism of exogenous and endogenerous substances. The present study focus on the establishment of zebrafish model with PXR gene null by use of CRISPR/Cas9 gene editing technology to provide a fundamental model for the studying of environmental toxicoloical analysis. Target sites of gRNA are designed and synthesized based on the sequence of PXR gene. The mixtures of gRNA and Cas9 mRNA were injected into zebrafish fertilized eggs during single cell phase via microinjection technical approach. Mutant with PXR gene null species were selected out through generational hybridization. Result showed that PXR gene in zebrafish was successfully knocked out by CRISPR/Cas9 technological approach, and sequence analysis exhibited 4 bp insert in the encoding PXR gene region.关键词：pregnane X receptor（PXR);CRISPR/Cas9;zebrafish
- 234
- |
- 153
- |
- 0
发布时间：2023-12-11 - 摘要：Mangrove endophytic fungiPenicilliumsp. H1N1 from Dongzhai Harbor of Hainan Province was fermented by liquid culture, and four compounds were isolated and purified by various chromatographic purification methods. Their structures were identified as 8-hydroxy-6-methyl-xanthone-1-carboxylate (1)，8-hydroxy-6-methyl-xanthone-1-carboxylic acid (2)，8-hydroxy-6-methyl-xanthone-1-carboxylate (3) and 4′,6-dihydrooxyaurone（4)，respectively. Furthermore, the structure of compound 1 was also confirmed by X-ray diffraction. Compound 4 was obtained from Mangrove endophytic fungi for the first time, providing a new natural source of aurones.关键词：endophytic fungus;Penicilliumsp.;secondary metabolites;flavonoids
- 160
- |
- 150
- |
- 0
发布时间：2023-12-11 - 摘要：Under the basic assumptions on generators，the one-to-one correspondence between convexity and conditional convexity ofg-expectations and generators of backward stochastic differential equations is obtained. Thus it is proved that the definitions of dynamic convex risk measures in Detlefsen-Scandolo (2005) and Jiang (2008) are completely same under the framework ofg-expectations. Moreover, the one-to-one relation between time consistent dynamic convex risk measures viag-expectations and convexity ofg-expectations is also established.关键词：backward stochastic differential equation;g-expectation;conditional convexity;dynamic convex risk measure
- 166
- |
- 158
- |
- 0
发布时间：2023-12-11 - 摘要：Ca2+is the most commonly used signal that appears as sustained oscillations to regulate many diverse cellular processes. Two-pool model is a classical mathematical model to explain how these Ca2+oscillations occur. However, the Hill coefficient in this model is too high to do mathematical analysis. In this paper, we improve the original model by lower the Hill coefficient. Based on the qualitative theory and bifurcation theory, we analyze the existence and stability of equilibrium points, and discuss the type of bifurcation points in the improved model. The improved model has similar dynamic properties as the original model, but a wider region for Ca2+oscillations and a more obvious amplitude change, which better reflects the information encoding role of Ca2+signaling. The results of two-parameter bifurcation analysis combined with parameter sensitivity analysis indicate that the efflux rate constant of Ca2+out of the cell, as well as the threshold constants for activation and pumping of Ca2+store have significant impact on Ca2+oscillations. The variation of these parameters may contribute to calcium-related disease. This research is not only helpful for studying the two-pool model from the mathematical aspect, but also for understanding the Ca2+signaling and related diseases.关键词：two-pool model;calcium oscillation;bifurcation analysis;parameter sensitivity analysis
- 210
- |
- 161
- |
- 0
发布时间：2023-12-11 - 摘要：The mathematical model of necrotic tumor growth with the third boundary is studied. The model comprises a parabolic equation and an ordinary differential equation. The tumor is assumed that the nutrient concentration determines the growth of the tumor which is spherical symmetry. Using the rigorous mathematical analysis method, the existence and uniqueness of the stationary solution of the model are proven.关键词：necrotic tumor;the third boundary;parabolic equation;stationary solutions;existence and uniqueness
- 135
- |
- 156
- |
- 0
发布时间：2023-12-11 - 摘要：The boundedness of Riesz transform associated to sub-elliptic Schrödinger operators on Stratified groups is proven. By this boundedness, the Hardy spaces associated to the Schrödinger operators are investigated. Because of the larger class of potentials considered here, the kernels of the operators are not Calderón–Zygmund type.
- 147
- |
- 152
- |
- 0
发布时间：2023-12-11 - 摘要：The uniform exponential instability ofGC(0e) -generalized evolution operator in Banach space is studied. Based on the definition of GC(0e) -generalized evolution operator, the necessary and sufficient conditions for uniform exponential instability are obtained via mathematical analysis and operator theory. The results extend some well-known results in exponential stability theory. The research is theoretically important for studying the instability of generalized evolution operator.
- 129
- |
- 142
- |
- 0
发布时间：2023-12-11
- Postal code：510275
- Tel：020-84112585，84113223 Email：xuebaozr@mail.sysu.edu.cn
- Technical support is provided by Beijing Founder electronics co., LTD 京ICP备09064830号-19
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0