最新刊期
卷 57 ， 期 6 ， 2018
- 关键词：arching effect;hingeless arch;arch axis coefficient;pillar spacing;metal mine
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发布时间：2023-12-11 - 摘要：The water resource vulnerability of the Pearl River Delta metropolises under the changing environment is multidimensional, changeable and uncertain, with the impact of multiple interference resulted from climate change and intensive human activities. This paper develops an index of water resource vulnerability evaluation of the Pearl River Delta metropolises based on VSD model including exposure, sensitivity and adaptive capacity. An integrated assessment is conducted on the water resource vulnerability of the Pearl River Delta metropolises in 1985-2015. The results show that (1) The water resource vulnerability increased in Shenzhen, Dongguan and Zhongshan, stabilized in Guangzhou, Foshan and Zhuhai, and decreased in Zhaoqing, Huizhou and Jiangmen. (2) The time trends of sensitivities and adaptive capacities are similar for all cities, but the time trends of exposures vary from each other. On average, the water resource per capita in cities with rising vulnerabilities is 19% of water stress state, under big stress of socioeconomic development. The water resource per capita in cities with steady vulnerabilities is 42% of water stress state, under medium stress of socioeconomic development. The water resource per capita in cities with decreasing vulnerabilities is 1.8 times water stress state, under the lowest stress of socioeconomic development.关键词：the vulnerability of water resource;VSD model;the Pearl River Delta metropolitan
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发布时间：2023-12-11 - 摘要：The research of Qinling's climatic condition variations is significant for the development of rice based on local conditions and the guarantee for stable rice production, because the Qinling, one of geographical boundaries and climate transition zones in China, is sensitive to climate changes. Based on daily data of 37 meteorological stations in the south of the Qinling Mountains from 1960 to 2016 and the methods of linear trend, climatic trend rate and spatial interpolation, the paper researched temporal and spatial variations of climatic conditions during the growth period of single-season rice. The results are as follows:① The heat resources tended to increase, the water and light resources tended to decrease in the past 57 years in the south of the Qinling Mountains. Especially since 1988, the temperature has become obviously higher and the climate has become warm and wet, and the lighting conditions have been relatively improved.②The average temperature and ≥10 ℃ accumulated temperature and the precipitation gradually reduced from south to north in the study area. The heat injure intensity (in July and August) gradually reduced from southwest to northeast, the drying index and sunshine hours were contrary to it. The diurnal range gradually reduced and the precipitation in the spike differentiation period increased from center to east and west. The sunshine hours of the fructicative period gradually increased from west to east.③ There were a small increment of the high value region of the average temperature and ≥10 ℃ accumulated temperature and a large increment of the low value region. The heat injure intensity was higher in the west of the study area. There were a smaller decrement of the low value region of the diurnal range and a large increment of the high value region. The spatial variation of precipitation was complicated, the rainy areas tended to be dry and the less rainy areas tended to be moist. The climatic trend rate of the dry index decreased in the east while rised in the west. The climatic trend rate of the light conditions decreased. The above results have a practical guiding value for the single-season rice cultivation in the south of the Qinling Mountains.关键词：single-season rice;south of the Qinling Mountains;climatic conditions;spatial interpolation;tendency rate
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发布时间：2023-12-11 - 摘要：Saga ophiolite from the mid-western part of the Yarlung-Zangbo ophiolite belt was researched in this paper. The data of petrogeochemistry, geochronology, chronology, geotectonics and geodynamics indicate that gabbro in Saga ophiolite was originated from calc-alkaline low-potassium tholeiitic basalt. The basalt in Saga ophiolite is calc-alkaline and alkali. The basalts in Rega and Songduo section line are calc-alkaline low-potassium tholeiitic basalts. The basite in Saga ophiolite has the same geochemical characteristics as MORB, tholeiitic and alkaline basalt. In summary, the Saga ophiolite in the northern sub-belt was originated from various multiple resources. It is generally depleted in Cr, Ti, Mn. The geochemical characteristics of trace elements are similar to mantle. A large area of alkaline basalt was found in the saga ophiolite, retaining geochemical characteristics of mantle with enriching alkali. Zircon U-Pb age of the gabbro in Dajiling-Sala profile is 125.6±2.7 Ma, in accordance with the basaltic age (130 to 120 Ma) in western Yarlung-Zangbo ophiolite. It is inferred that the Saga ophiolite is possible to form in the intra-oceanic supra-subduction zone (SSZ), suffering from expansion in mid-oceanic ridge situated in the forearc basin.关键词：Yarlung-Zangbo ophiolite belt;Saga ophiolite;petro-geochemistry;geochronology;tectonic significance;SSZ
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发布时间：2023-12-11 - 摘要：In order to alleviate urban congestion, it is necessary to establish an intelligent traffic management platform that can predict traffic flow. In this paper, the outlier detection algorithm based on the Spark is used to clean the real-time massive traffic flow data. Load balancing rules are designed for the parallel data registration and storage. Semantic parsing and logical optimization are used to realize distributed semantic queries. And the STARIMA model based on multi-order spatial weight matrix is designed to realize the traffic flow forecasting. By the comparison experiments, it is proved that: ① The traffic flow data cleaning, statistics, registration and storage methods effectively utilize the advantages of memory computing and iterative computing of the Spark framework. In the big data environment, this method reduces the time consumption by about 60% compared with the MPI method or MapReduce method. And it can complete the data preprocessing in one prediction cycle. ② The semantic query method provides data to the traffic flow prediction model. The multi-order spatial weight matrix of the model can reflect the multi-order traffic flow assignment law more accurately. Compared with the dynamic STARIMA model, the accuracy of prediction analysis can be increased by about 25%. And the method can provide reference for traffic guidance information publication.关键词：Spark;traffic flow prediction;data cleaning;correlation analysis;spatial weighting matrix
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发布时间：2023-12-11 - 摘要：We report on micromagnetic simulation results of the dynamical behaviors of magnetic vortex driven by spin polarized currents with three-point-contact geometry. The influence of the magnitudes, directions, and inter-distances of the spin polarized currents on the dynamical behaviors of magnetic vortex was studied. The results indicate that all the magnetic vortex configurations undergo similar gyrotropic motion and polarity switching with the increase of current density. Compared with the symmetrical contact point position, the vortex core can be excited more easily with the asymmetrical contact point position at the current direction of (1, 1, 1), which expands the current range of similar gyrotropic motion and shortens the time to the transient state of polarity switching. This result makes magnetic vortex more advantageous in the application of spin-torque nano-oscillator and magnetic storage. At the current direction of (1, 1, -1) the asymmetrical contact point position has little influence on the dynamical behaviors of magnetic vortex. It is the asymmetrical current direction that plays an important role in the dynamical behaviors of magnetic vortex.关键词：magnetic vortex;spin polarized currents;dynamical behaviors
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发布时间：2023-12-11 - 摘要：The dynamic finite element coupled model of track-embankment-foundation system was established for parametric effect on dynamic stresses of subgrade under high-speed train load. The influence of fastener stiffness and the elastic modulus of the CA mortar layer, supporting layer, surface layer of subgrade, bottom layer of subgrade, subgrade body, and foundation has been analyzed. Comparison between measured data of the full-scale model and the simulation results shows good agreement. The result of the analyses indicated that the elastic modulus of the supporting layer, bottom layer of subgrade and subgrade body has a bigger effect on the dynamic stress response on the subgrade. The elastic modulus of the bottom layer of subgrade has the biggest effect on the dynamic stress response on the subgrade. When the elastic modulus of bottom layer of subgrade increased from 60 MPa to 180 MPa, the surface layer of subgrade dynamic stress increased by 31.53%, the bottom layer of subgrade dynamic stress reduced by 14.43%, the subgrade body dynamic stress reduced by 16.10%.关键词：high-speed railway;embankment;dynamic stress;numerical simulation;full-scale model test
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发布时间：2023-12-11 - 摘要：Quasi-periodic motion is a kind of common phenomenon in practical engineering. It is also one of the ways from periodic motion to chaos. In this paper the incremental harmonic balance (IHB) method with multiple time scales is presented for the study of quasi-periodic motions of nonlinear systems. Two examples of Duffing and van der Pol-Duffing equations, quasi-periodic motions characteristics of the systems which subjected to the external multi-excitations are obtained. Moreover, the results obtained from the IHB method agree well with those from the numerical integration method using the fourth-order Runge-Kutta method. The numerical examples illustrate the IHB method with multiple time scales can be used to study quasi-period motions of nonlinear systems. It provides an effective method for the further study in nonlinear vibration field.关键词：nonlinear vibration;multiple time scales;IHB method;quasi-periodic motion
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发布时间：2023-12-11 - 摘要：A multi-body offshore platforms with weak nonlinear link chain was taken into consideration in this research. Thinking floating piers as mutual coupling units of network structure, boundary element method (BEM) can be used to obtain wave parameters, then floating platform‘s time domain response in different wave angles can be calculated by Runge-Kutta iteration method. The result of numerical calculation shows that the amplitude response area in beam waves is obviously greater than that in following waves, indicating that it is more difficult to find the frequency of non-response region in a situation of beam wave. In analysis of time domain responses, the max amplitude is sway in beam wave, and since sway in beam wave is significantly affected by bending resonance of internal system, jump of amplitude can be easily observed in specific wave angles.关键词：multi-body floating pier;weak nonlinear link;wave direction angle;jump of at amplitude
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发布时间：2023-12-11 - 摘要：This paper presents an analytical study on the mechanics response of simply supported beams with stiffness damage by combining the finite element method with the U-transformation method. Firstly, a simply supported beam is divided intonsubstructures, and an equivalent structure with cyclic periodicity is constructed, and the governing equations are established, in which stiffness damage is treated as a loading. Then U-transformation technic is applied to the equations and the analytical expression of nodal deflections of the beam are derived. The influences of damage location and damage degree on these solutions are discussed. Moreover, the natural frequencies of damaged beam are solved.关键词：simply supported beam;U-transformation method;damage;static analysis;natural frequency
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发布时间：2023-12-11 - 摘要：Taking into account the multiple types of floating cars and the different vehicles’ performance among distinct vehicle types, in order to obtain more accurate link speed, this paper distinguishes vehicle types and introduces artificial neural network technology to model the velocity of the floating vehicles and link speeds on highway. We apply the floating car data from Guangzhou Airport highway for model verification, and compared with the Bayesian Network based method. The results show that the average absolute relative error (MAPE) of the link speed before correction is about 20%, the average absolute error (ABS) is about 8 km/h, the MAPE of the link speed after correction is less than 10%, and the ABS is less than 5 km/h, which shows that the proposed method has good effect.关键词：multiple types of floating car data;road speed correction;artificial neural network;road speed of highway
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发布时间：2023-12-11 - 摘要：The effects of Compound Xueshuantong Capsule (CXC) on the hepatic and renal function of rats with disseminated intravascular coagulation were assessed. Biochemical tests showed that CXC could significantly decrease the levels of the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in liver, and the levels of the urea nitrogen (UN) and creatinine (CR) in kidney. Histological observations showed that CXC could significantly inhibit thrombosis, hemorrhage, and inflammation infiltration in both liver and kidney. The results indicated that CXC could significantly improve the liver and kidney function, providing useful references for its clinical medication.关键词：Compound Xueshuantong Capsule;disseminated intravascular coagulation;hepatic and renal function
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发布时间：2023-12-11 - 摘要：Key words:hyperspectral image,sugar beet,leaf nitrogen content,characteristic wavelength,support vector machines
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发布时间：2023-12-11 - 摘要：In order to search for the novel secondary metabolites from marine microorganisms,Penicilliumsp. GGF16-1-2 which was isolated from China starfish, was carried out by opening column chromatography, HPLC, etc. Seven known compounds were obtained from the EtOAc layer of broth ofPenicilliumsp. GGF16-1-2. Their structures were identified by physical data, spectroscopic analysis and comparing with the references, and these compounds were named as dicitrinones (1), microsphaeropsones (2), janthinone (3), microxanthone (4), emodin (5), 8-hydroxy-6-methylxanthone-1-carboxylic acid (6) and coniochaetone (7). Compounds 2, 4 and 6 were isolated from the genusPenicilliumfor the first time.
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发布时间：2023-12-11 - 摘要：FT-IR and FT-Raman are applied to characterize the molecular vibrational spectra of Clobetasol Propionate. The second derivative spectra are used to enhance the spectra‘s resolution. The results show that the spectra’s bands of Clobetasol Propionate can be more sufficiently assigned by combining two kinds molecular spectra. The research proves that the structure information of medicine can be obtained under no-destructive state.关键词：FT-IR spectra;FT-Raman spectra;second derivative spectra;molecular vibration spectra
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发布时间：2023-12-11 - 摘要：In this paper, the formation process of basic magnesium carbonate whisker unit cells, calculation of growth units stable energy, calculation of unit cells parameters, symmetry of the unit cells, as well as the structural characteristics are investigated and discussed from the perspective of growth units. The results show that the calculated results are in good agreement with the diffraction standard by comparing with the diffraction standard one by one.关键词：basic magnesium carbonate whisker;unit cells structure;unit cells parameter;stability energy
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发布时间：2023-12-11 - 摘要：The blowup phenomena of the solutions for the initial-boundary value problem of the non-isentropic Euler equations with damping is studied. It is proved that the solutions will blow up in finite time when a weighed functional associated with the initial momentum is large enough by using the integration method. Some recently known blow-up results are extended from the isentropic case to the non-isentropic case. And the blow-up result for the negative initial entropy case is obtained without the restriction that the adiabatic constant is not bigger than three.关键词：non-isentropic Euler equations with damping;initial-boundary value problem;blowup
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发布时间：2023-12-11 - 摘要：There exists hysteresis effects in many automatic control systems. Models of mathematical describing harmful matter to reactdiffuse process are some kind of differential equations with hysteresis in air cleaning system. Due to the nonlinearity of hysteresis factors, such as the destruction of many excellent properties of functions, many models with hysteresis characteristics hardly can be analyzed. Therefore, in the modeling of general automatic control systems, hysteresis factors are omitted. First, a class of hysteresis operators are introduced according to the functional principle of air purification system, and some important properties of hysteresis operators are given through a series of detailed analysis. Then the existence and uniqueness of the global classical solution of differential equation with hysteresis are proved by using the fixed point theorem. Finally, a decision model for calculating the investment and benefit of purification equipment is proposed.关键词：purifier;hysteresis operator;mapping;fixed point;decision model
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发布时间：2023-12-11 - 摘要：A class of Cauchy problems for the nonlinear nonlocal singular perturbation fractional order differential equation is studied. Firstly, the outer solution of the original problem is obtained. Secondly, using the stretched variables and the composing expansion method, the initial layers are constructed. Finally, using the theory of differential inequality, the asymptotic behavior of the solution to original Cauchy problem of nonlinear nonlocal singular perturbation fractional order differential equation is studied and the uniformly valid asymptotic estimation is discussed.关键词：nonlinear;fractional order equation;singular perturbation
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发布时间：2023-12-11 - 摘要：The non-negativity of curved is a key condition to characterize Riemannian manifolds. It is shown that any closed shrinking solitons with pinched Weyl curvature must have non-negative Ricci curvature. If further assume the soliton has positive Ricci curvature, then it must be trivial, that is, the solition is an Einstein manifold.关键词：pinched Weyl curvature;shrinking soliton;non-negative Ricci curvature;maximum principle
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发布时间：2023-12-11 - 摘要：The problem of the number of limit cycles for three classes of Liénard systems, that is, (m, n)=(9,7), (m, n)=(8,7) and (m, n)=(7,8) , are studied in the neighbourhood of the origin. The first ten, nine and nine singular point values for the corresponding accompany complex systems are calculated by using the computer algebra system, Mathematica, and the method of singular point values. Then, three kinds of Liénard system can generate at least ten, nine and nine limit cycles at the sufficiently small neighborhood of the origin respectively. And the exitence of limit cycle is proved by applying the Jacobian determinant method. It is the first time for giving the lower bound estimates for such systems, that is, H^(9,7)≥10,H^(8,7)≥9,H^(7,8)≥9.
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发布时间：2023-12-11
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