最新刊期
卷 57 ， 期 3 ， 2018
- 摘要：Mesh division scheme affects the efficiency of 3D geoelectric finite element (FE) modelling when using pre-conditioned conjugate gradient method. The tetrahedral mesh, which is derived from regular hexahedral mesh, is recommended after mesh analysis. Results from model computations reveal that the incomplete Cholesky conjugate gradient method (ICCG) and successive over-relaxation conjugate gradient method (SORCG) could succeed when employing uniform meshes. However, the non-uniform hexahedral meshes might lead to unsuccessful pre-condition matrix and ICCG might fail. In contrast, the presented tetrahedral meshes overcome this drawback and make ICCG a stable solver. Besides, the new mesh scheme could save 50% computer memories compared to traditional hexahedral mesh.关键词：mesh analysis;pre-conditioned conjugate gradient;finite element;3D geoelectrics
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发布时间：2023-12-11 - 摘要：The granite residual soils were sieved into five groups to study their tensile mechanics. The soil mineral compositions before and after HCL treatments were measured with X-ray diffraction, and the tensile strengthes of granite residual soils were tested with the direct tension apparatus. The changes of particles before and after HCL treatments were analyzed with micro-tomography method. The results showed that α-FeO(OH),α-Fe2O3and Fe3O4disappeared after HCL treatment. The tensile strength of different groups of soils firstly increased and then decreased with water content increasing (existing a convex peak). After HCl treatments, the iron and aluminum colloids wrapped around the basic aggregate units of the granite residual soils and the cements between the different structural units were consumed in the chemical reaction with HCl treatments, which resulted in the particle sizes of the granite residual soils decreasing. The destruction of microstructures led to the granite residual soil aggregates losing cements binding. The decreasing suctions, especially the structure suctions, between grains of the granite residual soil led to that the samples were easily broken under the direct tension effect.关键词：granite residual soil;tensile strength;chemical constituents;X-ray diffraction;HCl;micro-tomography method
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发布时间：2023-12-11 - 摘要：The Mangshan(MS) loess is located on the south bank of the Yellow River near the southwestern part of the North China Plain, well outside of the Chinese Loess Plateau (CLP). Stratigraphically, the uppermost～100 m loesspaleosol sequence, formed in the last two climate cycles, is extremely thick compared with the eolian deposits in the CLP. Previous researches revealed that, unlike other sections in the CLP, the MS loess since deposit of S2(about 200 ka) is characterized by exceptionally high accumulation rates, lower magnetic susceptibility values and coarser grainsize distribution. The Yellow River flood plain adjacent to the MS loess is considered as the dominant source of the accumulated loess, but the proof in geochemistry is absent. The trace element (TE) and rare earth element (REE) characteristics of the MS loess bear information about climate change, and may give insight into the dust sources. We present the loess comparison of TE and REE compositions in MS, Sanmenxia (SMX, i.e., the Sanmen Gorge) area, CLP and Huainan(HN) since deposit of S2. The results show substantial differences in Zr/Hf, Nb/Th, Y/Th and La/Th values when compared the MS loess with the SMX, CLP and HN loess, leading to an important indicator for provenance. Specifically, the MS loess shows a higher Zr, Hf and a lower Th, Cs, implying a coarser grainsize distribution. The difference in TE composition between the MS loess and the other eolian deposits is also shown in the ternary diagrams of La-Th-Sc and Zr/10-Th-Sc, in which the MS loess projection region is incompletely consistent with that of the SMX, CLP and HN loess. Most probably, these were all derived from the difference of dust sources. The REE study of the MS loess and its comparison with the loess of SMX, CLP and HN show a lower ΣREE, LREE/HREE and La/Eu value. The MS loess samples exhibit an exceptionally distinctive projection region in the ternary diagrams of 10*Hf-Ce-Yb and La-Zr/10-Ce. Both of them are reasonably classified as another provenance. All results present that the dust source of the MS loess may be disparate from that of SMX, CLP and HN, implying that the alluvial fan adjacent to MS may contribute significantly to the accumulation of the MS loess-palaeosol sequences since deposit of S2. The Yellow River flowed out through the Sanmenxia in about 200 ka, releasing most of its suspended load due to a dramatic decrease in gradient and forming an excessive deposition of the alluvial fan. Such excessive deposit compensation provided a major source for the MS loess accumulation.关键词：Mangshan loess;trace element;rare earth element;geochemistry;provenance
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发布时间：2023-12-11 - 摘要：By using the Flux Source Area Model (FSAM), the flux source area of suburban lawn in Zhuhai City was analyzed under different stability and different time scales. The results are shown as follows: ① The southeast wind is prevailing with a percentage of 48.36%. ② Under the 90% contribution level, the area of flux source varies with atmospheric stability, there are much larger areas of flux source, up to 155 m, in stable atmosphere. ③ The area of flux source obviously changes with the seasons. The area of flux source changes from large to small in the order of winter, autumn, spring and summer under the stable atmosphere, while it does not change in spring and autumn under the unstable atmosphere. ④ The area of flux source is smaller in day time than in the night. The minimum visual distance of 31m was obtained at 12∶00. In addition, the area of flux source could be influenced by underlying surface, observation height and contribution level (P). Therefore, FSAM was considered as model that can reflect the flux source area of the suburban lawn in Zhuhai City.关键词：Zhuhai;eddy covariance technique;FSAM;suburban lawn;turbulent flux
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发布时间：2023-12-11 - 摘要：In this paper, the influence of the spring soil moisture in the Indo-China Peninsula was analyzed on summer precipitation over the South China Sea and surrounding area by using statistical methods like SVD. The results indicate that there exists obvious positive correlation between soil moisture and summer precipitation over the western Pacific Ocean and negative correlation between soil moisture and summer precipitation over the eastern Indian Ocean. Summer precipitation increased over the western Pacific and decreased over the eastern Indian Ocean when positive (negative) anomaly in soil moisture occurred over the Indo-China Peninsula. When soil moisture anomaly over the Indo-China Peninsula was positive, local evaporation increased, near surface humidity decreased, latent heat flux from ground to atmosphere increased, surface albedo decreased, the absorption of solar shortwave radiation was strengthened, and upward shortwave radiation correspondingly decreased. This resulted in that near surface temperature decreased, sensible heat flux and long-wave radiation decreased, and the sea-land thermal difference reduced, which enhanced the monsoon and caused monsoon to occur earlier. Furthermore, that enhanced the transportation of water vapor from the eastern Indian Ocean to the western Pacific Ocean, and increased the precipitation in the western Pacific. The increase in near surface temperature will lead to the opposite precipitation mode, and vice versa.关键词：Indo-China Peninsula;the South China Sea;soil moisture;summer precipitation
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发布时间：2023-12-11 - 摘要：The study results of the palaeoflood in the upper reaches of the Hanjiang River suggest that six loess-paleosol sedimentary profiles may record a palaeoflood event in the Eastern Han Dynasty. Four sedimentary profiles (LJZ, TJZ, QFC-B and LWD-A) located in Yunxi-Yunxian section with relatively concentrated distribution are selected as research objects. Based on appropriate terrain data and appropriate hydrological parameters, the HEC-RAS model was used to calculate the water surface line and flood routing simulation in the Eastern Han Dynasty. The results show that the simulated water level of 4 profiles is in good agreement with the estimated water level in the field survey, and the errors are less than 0.25%. The peak propagation time is about 3 h, and the peak discharge is reduced by 1.43%, which is consistent with the flood propagation characteristics in the upper reaches of the Hanjiang River. This suggests that the simulation results based on the HEC-RAS model for palaeoflood events in the Eastern Han Dynasty are relatively reliable. In addition, it also shows that four sedimentary profiles may record a palaeoflood event in the Eastern Han Dynasty. The study has scientific significance for fully understanding the flood evolution law in the upper reaches of the Hanjiang River; it has important practical significance for flood control and flood forecasting in the Hanjiang River Basin.关键词：Eastern Han Dynasty;palaeoflood research;HEC-RAS model;upper reaches of Hangjiang River
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发布时间：2023-12-11 - 摘要：The generalized center problem of elementary resonant singular point for an extensive class of complex autonomous polynomial differential system in C2is studied. A new method (integrating factor method) is introduced to determine generalized center of resonant singular point for any rational resonance ratio. A recursion formula of calculating saddle point quantities is obtained and the relation of the saddle point quantity and the generalized singular point quantity is given. A gap in Doctoral thesis of Ping Xiao is fixed.关键词：resonant singular point;generalized center;integrating factor;generalized singular point quantity
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发布时间：2023-12-11 - 摘要：A semi-negative definite matrix gradient system representation for a type non-autonomous generalized Birkhoff system is studied. The condition under which a non-autonomous generalized Birkhoff system can be considered as semi-negative definite matrix gradient system is obtained. The characteristic of seminegative definite matrix gradient system is then used to study the stability of non-autonomous generalized Birkhoff system. Examples have been given to illustrate the applications of the results.关键词：non-autonomous generalized Birkhoff system;semi-negative definite matrix gradient system;stability
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发布时间：2023-12-11 - 摘要：A modified HIV infection model with saturation incidence is studied. By analyzing the corresponding characteristic equations, the local stability of an infectionfree equilibrium E0(T00,0) and a positive equilibrium E*(T*I*V*) is discussed. By using suitable Lyapunov functions and the LaSalle invariant principle, it is proved that if the basic reproductive number R0<1, the infectionfree equilibrium E0(T00,0) is globally asymptotically stable. If the basic reproductive number R0>1, by means of the second additive compound matrix, the globally asymptotical stability of the positive equilibrium E*(T*I*V*) is obtained. Numerical simulations are carried out to illustrate the main theoretical results.关键词：HIV infection;saturation incidence;Lyapunov function;LaSalle invariant principle;the second additive compound matrix
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发布时间：2023-12-11 - 摘要：The traveling wave solution of a generalized Camassa-Holm equation is mainly studied. All elementary integral forms of the traveling wave solution of the equation are calculated by direct integral method. In particular, the exact traveling wave solutions in special cases are obtained.关键词：generalized Camassa-Holm equation;direct integral method;the traveling wave solution;Cardan formula
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发布时间：2023-12-11 - 摘要：The lag synchronization of the master-slave chaotic Chua's circuits via linear state-error feedback control with the channel delay is studied. Several algebraic criteria for the chaotic lag synchronization subject to the special control gain matrices are rigorously proven by means of the Strums theorem and factorization theorem in polynomial theory. It is verified by comparison of the numerical examples with such criteria existing in the literature that the new criteria are less conservative.关键词：chaos synchronization;Chua's circuits;linear stateerror feedback control
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发布时间：2023-12-11 - 摘要：A Cayley graph Γ=Cay(G,S)is said to be normal if Gis normal in Aut(Γ). The concept of normal Cayley graphs was first proposed by XU Ming Yao and it plays an important role in determining the full automorphism groups of Cayley graphs. The Cayley graphs on finite nonabelian simple groups are received most attention in the literature. However, examples of connected arctransitive nonnormal Cayley graphs of small valency on nonabelian simple groups are very rare. An example of a nonnormal 2-transitive pentavalent Cayley graph on the alternating group A119is constructed and it is showed that the full automorphism group of this graph is isomorphic to the alternating group A120.关键词：symmetric graph;simple group;automorphism group;nonnormal cayley graph
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发布时间：2023-12-11 - 摘要：In order to investigate the chemical constituents from Adenosma glutinosum comprehensively, the chemical ingredients of the ethyl acetate, petroleum and nbutanol fraction of the extracts were isolated. Then, twelve compounds were obtained by various chromatographic techniques. Their structures were determined by spectroscopic analysis and literature comparison method, they were: 30-oxo-betulinic acid (1), 1,3,5-trimethoxybenzene (2), 3,5-dimethoxyacetophenone (3), β-sitosterol (4), stigmasterol (5), physcion (6), sesamin (7), precocene Ⅱ (8), palmitic acid (9), hexacosyl alcohol (10), D-allitol(11), apigenin-7-O-β-D-glucuronide butyl ester(12), respectively. All compounds were isolated from this plant for the first time.关键词：Adenosma glutinosum (L.) Druce;chemical constituents;structure identification
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发布时间：2023-12-11 - 摘要：The mechanism of optical isomerization of valine molecules with dual-hydrogen bonds between amino and carboxyl groups and the damage induced by hydroxyl radicals in water environment were studied by using MP2/6-311++G(2df, pd)// B3LYP/6-31+G(d, p) dual-theory and SMD model method for self consistent reaction field (SCRF) theory. The study of reaction channels showed that there were three channels a, b and c in the optical isomer reaction of valine in water environment. Using water cluster as medium, the protons transfered from one side of the α-carbon to the other side with N atom of amino group, O atom of carbonyl group and carboxyl group as bridges. The hydrogen abstraction reaction which damaged the valine molecules happened in channel a, and the water molecules were assistants. The potential energy surface calculation showed that when two or three water clusters were used as hydrogen transport medium, they acted a good catalytic action on the process of hydrogen-transfer of Optical Isomerization, and reduced the barrier of reaction vs naked reaction. Water solution effect had good catalytic activity in channel a, but catalytic activities were not obvious in channel b and c. The reaction barrier of hydrogen abstraction reaction which damaged the valine molecules with water molecules as assistants was low. The water solution effect has a big impediment effect on this reaction.关键词：optical isomerization;valine;density functional theory;transition state;perturbation theory;solvent effect;hydroxyl radical;damage
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发布时间：2023-12-11 - 摘要：We previously screened and obtained a novel pyrethroid-hydrolyzing gene sys 410 from Turban Basin metagenomic library, which was expressed in E coli BL21 (DE3) in soluble form. Here, to enhance the production and activity of the enzyme, flaskshaking medium and fermentation condition were investigated. The optimum medium was as follows: glycerol 20.0 g·L-1yeast extract 20.0 g·L-1ammonium sulfate 8.0 g·L-1phosphate 100.0 mmol·L-1magnesium sulfate 5.0 mmol·L-1trace element solution 1.5 mL·L-1. The optimum conditions of flaskshaking fermentation were as follows: loading volume 50/250 (V/V), initial medium pH 7.0, inoculum size 2%, lactose induction for 6 h. We also studied highdensity fermentation of the recombinant strain in 75 L fermenter. The results showed that dispersed oxygen supply, low concentration of the initial medium, and carbon and nitrogen fedbatch culture could stimulate the growth of the recombinant strain. Inducible expression started at the middle and later stages of logarithmic growth with 6 g·L-1lactose at 37 ℃. After 10 h, cell density reached 142.6 and the enzymatic activity was 3 105.1 U·mL-113.7 and 31.9 times better than those of the flaskshaking fermentation, respectively. In addition, crude enzyme powder was obtained after sonication and freeze drying with the amount of 68.4 g·L-1of fermentation broth. The specific enzyme activity was 119 426.9 U·g-1Remarkably, the enzyme was able to efficiently degrade all tested pyrethroids within 15 min, reaching over 95% conversion.关键词：pesticide degradation enzyme;high density fermentation;pyrethroids;biodegradation
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发布时间：2023-12-11 - 摘要：To determine polymorphic features of 25 Y chromosome Short Tandem Repeats (Y-STR ) loci in the Zhuang ethnic and their differences from the corresponding features in other ethnics in the Guizhou province, we analyzed the 25 Y-STR loci in the Zhuang ethnic population to obtained genetic polymorphism of the ethnic group. We amplified 25 Y chromosome Short Tandem Repeats loci from the DNA samples of 67 people of Zhuang ethnic using an Y27 Plex fluorescence detection kit, followed by electrophoresis with a Genetic Analyzer. Genotyping results were analyzed with a series of genetic software, including Arlequin 3.5, Mega 7.0, and SPSS19.0. Two doublecopy loci DYS385ab and DYS387S1 were found to have 8, 10 alleles, whereas the remaining 23 single-copy loci were found to have 86 different kinds of alleles with the allele number varying from 2 to 7, the allele frequency ranging from 0.014 9 to 0.970 1, and the genetic diversity varying from 0.058 8 (for DYS456) to 0.823 6 (for DYS387S1). A total of 36 haplotypes were detected, of which 66.7% were unique. The haplotype diversity was 0.957 9. The Rstgenetic distance matrix showed that the genetic structure of the paternal network of the Zhuang ethnic group in Guizhou was similar to that of the Fujian She ethnic and Inner Mongolia Mongolian. The polymorphism of the 25 Y-STR loci in Guizhous Zhuang ethnic group differed significantly from that of the Yunnan Hani, Xinjiang Uygur, Liaoning Manchu, Jilin Korean and Salzburg, with the greatest difference from that of the Xinjiang Kazak, Amdo Tibetan, and West African people. The 25 Y-STR loci in the Guizhou's Zhuang ethnic group had great genetic polymorphisms, which can be used in the identification of parental relationship.关键词：Y-STR;haplotype;genetic polymorphism;Zhuang ethnic group
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发布时间：2023-12-11 - 摘要：To provide a method for screening patients with sleep apnea hypopnea syndrome (SAHS), the heart rate variability (HRV) was applied to the classification of sleep respiratory events. The probabilistic neural network (PNN) was proposed to classify the normal and abnormal sleep respiratory events according to the HRV features to achieve the purpose of preliminary screening of the disease. In this classification process, the HRV features of ECG were firstly extracted from the polysomnographic monitoring data related to the normal and abnormal sleep respiratory events, and then normalized as the features. Then, PNN classification algorithm was used to train and classify the features. The prediction and classification performance of the model was finally evaluated. The results of the PNN classifier for the accuracy, sensitivity, specificity, area under the receiver operating characteristic curve (AUC) of the subjects and time consumption for classification were respectively: 75.97%, 82.51%, 76.22%, 0.7936 and 0.63 s. Compared with generalized regression neural network (GRNN) and extreme learning machine (ELM) classification algorithms, PNN classification algorithm is optimal in sensitivity, specificity, AUC and time-consumptions. In this study, HRV and PNN classification algorithm were used to classify the presence or absence of abnormal sleep respiratory events, thus providing a low physiological load SAHS screening method. The study has a certain practical significance for the initial screening of the disease.关键词：heart rate variability;sleep respiratory event;machine learning;classification algorithm
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发布时间：2023-12-11 - 摘要：Based on the wave diffraction theory in the two-layer fluid, and with the use of eigenfunction method, the wave potentials of ocean surface wave and internal wave diffraction in two-layer fluid caused by arc-shaped bottom-mounted breakwater are derived, and accordingly the wave forces and moments on breakwater are analytically calculated. The result shows that in two-layer fluid, the maximum dimensionless wave loads caused respectively by surface wave and internal wave may have the same order of magnitude. The relative variation of incident wave angle, two layer fluid density ratio, sea water condition and breakwater structure geometry condition may have some influence on diffracted wave effects, and there are some differences between the variation of surface wave effect and that of internal wave effect Because of interference from internal wave, the diffracted effects of surface wave in two fluid are different from that of surface wave in uniform ocean.关键词：arc-shaped bottom-mounted breakwater;two-layer fluid;surface wave and internal wave;eigenfunction expansion approach;wave diffraction
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发布时间：2023-12-11 - 摘要：Twin fibers pull out tests have been designed and carried out to obtain load-displacement curves. Simultaneously, such tests have been simulated by setting a 3D numerical model, which adopts material heterogeneity. Mechanical properties of twin fibers pull out test can, therefore, be studied by changing embedment depth. The results include tensile stress distribution, load-displacement curves, load-AE-step curves and AE evolution, and these results show that the change of twin fibers embedment has great influence on stress distribution. With an increasing embedment depth, peak load and toughness increase either. In addition, similar trend of load-displacement curve of twin fibers pull out test could be observed in both laboratory experiment and numerical simulation.关键词：twin fibers pull out;embedment depth;3D;fiber reinforced concrete
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发布时间：2023-12-11 - 摘要：The Noether quasi-symmetry and the conserved quantity for a fractional Lagrange system are studied by using the time-reparameterization method. Firstly, the fractional Lagrange equations in terms of Caputo derivatives are derived; Secondly, the definition of fractional conserved quantity for the fractional Lagrange system is given, and based on the special infinitesimal transformations of group without transforming time, the definition and the criterion of the Noether quasisymmetry for the fractional Lagrange system are given, and Noether's quasi-symmetry theorem is established; Finally, the definition and the criterion of Noether quasi-symmetry for the fractional Lagrange system under the general infinitesimal transformations of group with transforming time are given, Noether's quasi-symmetry theorem is derived by using the time-reparameterization method. An example is given to illustrate the application of the results.关键词：time-reparameterization;Caputo derivative;Lagrange system;Noether quasi-symmetry;conserved quantity
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发布时间：2023-12-11 - 摘要：Speed is the most critical factor of road safety, higher speed and speed changes increase the number of accidents and the probability of casualties. There is an urgent need in China to develop a relatively clear speed management framework and system speed management measures. Through the empirical study of the relationship between speed and accident, it is found that higher speed limit road is more likely to cause higher mortality rates, and speed shifting areas including accesses of expressway and other urban roads are inclined to cause accidents and serious consequences. Taking the speed management methods in developed countries as reference, speed management framework was proposed in Shenzhen, including two aspects, namely safer speed and safer speed change, the key measures under this framework mainly contains speed limit adjustment of road segements, expressway speed management and access speed management, which can effectively improve the level of road traffic safety.关键词：traffic safety;speed management;speed switching;speed limit zone;access management;fault-tolerant design
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发布时间：2023-12-11 - 摘要：To diagnose damages within retaining wall structures, based on impulse response function and virtual impulse response function, the damage feature vector spectrum was created and a damage identification index was proposed. Based on the damage feature vector spectrum and damage index, a damage diagnosis method for retaining wall structures was proposed. In order to verify the feasibility and validity of this damage diagnosis method, vibration tests on a pile plate retaining wall were performed under impulse excitation and ambient excitation, the damages within the wall were diagnosed via the damage feature vector spectrum and damage index. The tests results show that the damage state of the wall can be sensitively distinguished by the damage feature vector spectrum, damage location of the wall can be validly diagnosed through the damage index trend surface, and damage intensity of the wall can be quantitatively identified through the quantitative relationship between the damage index and damage intensity. Due to the influence of excitations, the stability of the damage index which is based on the impulse response function is poor relatively under impulse excitation, while the stability of the damage index which is based on the virtual impulse response function is much better under ambient excitation.关键词：retaining walls;damage diagnosis;damage index;impulse response function;virtual impulse response function
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发布时间：2023-12-11
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