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摘要：Cutter suction gas hydrate solid state fluidized mechanical mining is one of technical solutions proposed for seabed hydrate mining. Based on the discrete element method (DEM), a quasi-3D numerical simulation model for single-tooth cutting hydrate is established to study the hydrate breaking process and the force of the cutter teeth in the cutting process. The results show that:1) Hydrate fracture still follows the failure mechanism of rock, pure hydrate is plastically destroyed, and marine hydrate deposition is brittle fracture; 2) the deeper of cutting thickness, the larger volume of the collapsed marine hydrate deposits; 3) when the cutting thickness is less than 8 mm, the cutting force increases linearly with the cutting thickness. The feasibility of study to crush hydrate by threedimensional discrete element method. The research results can provide basis for the design and mining parameters of the cutter suction mechanical mining and the cutter head.  

摘要：It is difficult to identify the early fault of the rolling bearings. A diagnosis method based on variational mode decomposition (VMD) and Mahalanobis distance support vector machine (SVM) is proposed. Firstly, the original vibration signal is de-noised by wavelet threshold method to obtain effective vibration signal. Secondly, according to the center frequency of each mode after VMD decomposition, the final number of decomposed layers is determined. At the same time, the energy characteristics are extracted from the decomposed variational modal components. Finally, in order to measure distance between samples more accurately, Mahalanobis distance is introduced into the calculation of the Gaussian kernel function of the SVM, and a Gaussian function kernel based on Mahalanobis distance is established, which is used to support the vector machine classifier. Improved SVM is employed to identify the running state of the bearing, the experimental results show that the proposed method has high accuracy in identifying the normal state, the inner ring, the outer ring and the ball body fault of bearings.  

摘要：A trajectory big data mining method based on spatial-time Hausdorff distance segmentation and word vector similarity is designed in this paper. It can analyze the accompanying rules accurately and efficiently, and truly reflect the flow behavior of people and vehicles. The one-to-three Hausdorff distance algorithm based on time series characteristics can exclude the reverse trajectory and mine the accompanying relations. The set of trajectory segments separated by the time sliding window can establish the basis for the similarity measurement. The method of trajectory similarity measurement based on word vector establishes the analogical relationship between trajectory and sentences, reflects the spatial, temporal and directional heterogeneity of the trajectory, and accurately measures the structural similarity of the accompanying trajectories. It provides a reference for exploring similar objectives, detecting frequent paths as well as other related applications.  

摘要：In this paper, on basis of the determinant for the metric tensor, together with the identities got via anti-symmetrizing the Kronecker delta symbol and Levi-Civita tensor, we prove one of the properties of the Levi-Civita symbol (tensor), which shows that two Levi-Civita symbols (tensors) with the contraction for some or total indices can be expressed by a series of Kronecker delta symbols or the generalized Kronecker delta symbol. We further present two important deductions from the property of the Levi-Civita tensor, which are proved in other ways. Besides, we analyze several important properties for the generalized Kronecker delta symbol.  

摘要：Inverse identification of time history of wave load obtained from the measured structural response can provide a reliable load information for the design and health monitoring of marine structures. In this paper, a random wave load inversion method based on recursive optimization algorithm is proposed. This method establishes an objective function based on Newmark-βfor every time step and then, the wave load is identified from the measured acceleration recursively. As is noteworthy, the identified load at every time point is recursively derived from the measured acceleration and the load at the former time point for which the involved optimization problem is at small scale, and consequently, the whole load inversion procedure is very efficient.A numerical example on a two-story ocean structure shows that the proposed method can effectively identify the random wave load and is insensitive to measurement noise.  

摘要：The indicator of “Parking service level” is defined for curb parking to describe the probability that the drivers can find the available parking space. An integer optimization model is proposed to maximize the parking service level considering the rate of utilization of parking lot, so that a combination of the rate and the capacity of parking lot can be used to optimize the price scheme. A case study of an curb parking in Guangzhou CBD was presented, it verified the validity and rationality of the indicator parameters and models, and the study was found that the current combination of the rate and the capacity of parking lot led to a lose-lose for both the users and operator.  

摘要：This paper mainly investigated Noether symmetry and conserved quantity of nonholonomic controllable mechanical systems in phase space on time scales. The Hamilton equation for nonholonomic controllable mechanical systems on the time scale is established. We offered the definitions and criteria of the generalized Noether quasi-symmetry, and conserved quantities deduced from the generalized Noether quasi-symmetry are obtained. In the end of the paper, an example is given to illustrate the application of the results.  

摘要：The construction of underground project can be seriously affected due to the uncertainty and ambiguity of geological conditions. However, the geological risk factors are not given a thorough consideration in the risk assessment methods, while the weight is determined subjectively. In this paper, six first-level geological risk assessment indicators: soil mechanical properties, rock mass properties, inrush conditions, groundwater, karst, and regional stability are selected. Each of first-level indicators is characterized by several secondary-level evaluation indicators. Then a more comprehensive and reasonable geological risk evaluation index system is established by integrating and applying existing evaluation methods of single geological risk evaluation indicators to determine the risk level of the first-level evaluation indicators. In view of the diversity of the indicators and the incompatibility of the assessment result given by a single indicator, a geological risk assessment model is established based on the extension method. The simple correlation function in extension theory is used to calculate the weight of each indicator, which is more objective and reasonable than traditional methods. The model was adopted to evaluate the risk of a station in Guangzhou. It is found that the geological risk level division is reasonable, and can reflect the local geological risk situation objectively; the geological risk level of the station in untreated condition is “moderate risk”, and the eigenvalues of risk grade is 1.94, which indicates that “moderate risk” is biased toward the “low risk” level. The assessment result agrees with the site investigation, so the evaluation result is precise.  

摘要：Paleozoic cherts outcrops were widely developed in the Mianlue tectonic belt, which could reveal the sedimentary environment and tectonic background of southern Qinling orogenic belt. In Sanchazi area, the cherts were found in the Sanhekou Group of the Middle Devonian. Geochemical analyses showed that Sanchazi cherts were high in SiO₂(94.04%-98.08%, with a mean value of 96.92%) and low in Al₂O₃and TiO₂and were relatively high in Ba and U, but was relatively low in Zr for trace elements. The U/Th and Ba/Sr ratios were relatively high too. ΣREE content was significantly low (7.61-51.04 μg/g, with an average valve of 2251 μg/g). PAASnormalized REE distribution pattern inclined to the left, rich in HREE and with positive Eu anomaly and negative Ce anomaly. The Al/(A1+Fe+Mn), Fe/Ti and (Fe+Mn)/Ti values indicated the origin of hydrothermal sedimentation of the cherts. Al/(Al+Fe), Al₂O₃/(Al₂O₃+Fe₂O₃+MnO), Al2O3/(Al₂O₃+Fe₂O₃), δCe and (La/Ce)N values indicated that the cherts were mainly formed in the continental margin. The values of (La/Lu)N, (La/Yb)N and δEu could be related to the hydrothermal activities controlled by the deep fractures. Th/U, U/Th, δU values indicated the cherts were formed in the anoxic depositional environment. The above-mentioned geochemical evidences inferred that Sanchazi cherts were formed in a sedimentary environment of rifted basin at continental margin in the north of South China Block during the Paleozoic. During the rifting period, while a series of extensional structures, such as rift or fault basin and syngenetic faults, were formed, accompanied magma activities could provide heat source for the thermal water, and the regional syngenetic faults provided the channel for upwelling of the thermal water. Hence, the convective hot water became rich in SiO₂through the leaching and dissolving of chemical composition from surrounding strata, and contributed to the forming of hydrothermal sediment cherts of different geologic ages in the Mianlue tectonic belt.  

摘要：The seasonal variations of tidal currents in the Haikou Bay are analyzed based on the obtained data in 2016. The results demonstrate that: (1) the irregular diurnal tides were observed during spring, summer and autumn, while the irregular semi-diurnal tides were obtained in winter. (2) Because of the eddy influence, it is easier to obtain the irregular semidiurnal tidal currents near the cape area. (3) The tidal currents are mainly M₂K₁and O₁and their constituents are similar. (4) The strongest water transportation is from east to west in winter. (5) In this area, there are compensation currents during spring, summer and winter, while no obvious compensation currents could be obtained in autumn.  

摘要：ARW-WRF and GSI 3D-Var methods were used to build a set of operational prediction systems and assimilate Doppler Weather Radar （DWR） reflectivity and velocity, Himawari-8 meteorological satellite AHI data. Regarding problems of data application and forecasting effect of unconventional data, multiple sets of comparative experiments were designed to perform simulation analysis and assessment of data assimilation (DA) results based on a case of severe precipitation process in southern China. The results show that during the heavy precipitation period in the coastal areas of Guangdong on 17-18 July 2017, the system can grasp the scope and intensity of precipitation and the simulation of radar reflectivity. Particularly, the assimilation of satellite data has ability to analyze cloud-water materials and weather process on the sea. Assimilating conventional data, radial velocity, reflectivity, and satellite data can improve simulation tactics such as temperature, wind vector, humidity, and precipitation. However, their prediction results are not absolutely superior to the test of certain types of data.  

摘要：Key words:IGF-1; IGF-2; IGF-3;Epinephelus coioidesoocyte,expression analysis  

摘要：As general ground dwelling predators of many agricultural pests, Carabid beetle community responds to the environmental disturbance and climate warming, and thus is intensively related with occurrence of arthropod pests. With changes of climate and land use, the community of ground beetles in the black soil cropping area of the Sanjiang Plain is bound to be affected. In this study, a total of 1 527 carabid beetle adult individuals belonging to 36 species were collected from18 sampling sites located in poplar woodlands and corn fields at different latitude. Pitfall trapping was used to investigate the species richness and individual abundance of Carabid family. The diversity index of ground beetles was also calculated. The effects of latitude difference and land types on these indicators were studied. Relationship of abundance between ground beetle species and other related arthropod groups was also analyzed. Among the samples,Dolichus halensisDolichus halensisandPterostichus gebleriwere found to be the dominant species in this area. Correlation analysis between the species richness and individuals of ground beetles indicated that species richness and individuals of ground beetles were significantly positive correlated. Under different latitudes and land use types, there were significant differences in the number of individual for specific carabid beetle species: the number of individuals in the three latitudes was ChangchunDolichus halensisPterostichus gebleriandSynuchus congruoushad a significantly positive correlation; and these species had a significant correlation withOrthoptera. Analysis of variance for the most abundant 7 species ground beetles showed that the number ofHarpalus pallidipennisin different land types was significantly different;Dolichus halensisvaried significantly at different latitudes and land typesSynuchus congruousis significantly different in these two land types, the total number of ground beetles is significantly different at different latitudes and different land types. There was no significant interaction between latitudes and land use types. Overall, the activity-density of carabid beetles at lower latitude was less than that at higher latitudes, and the number of ground beetles in corn fields is bigger than that in woodland. As the climate warming, the number of ground beetles will decrease; and as the type of land use changing from woodland to farmland, the number of ground beetles will increase. Moreover, these big body size carabid beetle species (Dolichus halensisPterostichus gebleriandSynuchus congruous) might have some overlap in prey spectrum.  

摘要：The study reported a novel drug delivery system, red blood cell membranes biomimetic nanoparticles (RBCM-NP) drug delivery system. The system was constructed by combining the excellent drug-carrying properties of nanoparticles and cell membranes as shells to encapsulate the synthesized nanoparticle which makes it disguise as an endogenous substance to reduce uptake of reticuloendothelial system and immune recognition. Nanoparticles (NP) were prepared by reverse solvent method, while red blood cell membranes (RBCM) were extracted by centrifugal extraction. Different ratios of RBCM and NP were co-extruded for different times to prepare RBCM-NP. RBCM-NP were characterized by transmission electron microscopy and Malvern particle size meter. The aggregation reaction of biotinylated nanoparticle (BTNP) and streptavidin (ST) were used to study the coverage of red blood cell membranes. The particle sizes of NP and RBCM-NP were uniformed. In optimized formulation, RBCM could completely encapsulate NP with good reproducibility.  

摘要：The studyinvestigated the damage of ibuprofen molecules with two conformations induced by hydroxyl radical and the effect of water solvation in water vapor environment. The methods were density functional theory using the B3LYP functional, ab initio MP2 and Slovation Model Density (SMD) model method based on self consistent reaction field theory. The study showed that ibuprofen molecule damage had two mechanisms: α-H abstraction of hydroxyl radicals(water clusters) and hydroxyl radicals addition to benzene ring. The calculation of potential energy surface showed that, for ibuprofen conformation-1, the reaction channel of αH abstraction of hydroxyl radicals assisted by water molecular had an advantage, where the energy barrier of α-H abstraction was 34.68 kJ·mol^-1. For ibuprofen conformation-2, the reaction channel ofα-H abstraction of hydroxyl radicals had an advantage, where the energy barrier of α-H abstraction was 34.81 kJ·mol^-1. In addition, the energy barrier of hydroxyl radicals addition to benzene ring was about 26.00 kJ·mol^-1, and damaged ibuprofen molecules were difficult to repair. The effect of water solvation had little effect on the ibuprofen molecules damage induced by αH abstraction of hydroxyl radicals(water clusters) and hydroxyl radicals addition to benzene ring.  

摘要：Density estimation is considered for negative association samples X₁X₂…,X_n. A linear wavelet density estimator is defined by using wavelet method, and theL^p(1≤p≤∞) mean consistency of estimator are proved without any assumptions of smoothness for density function. The results show that wavelet estimator can effectively estimate density function of NA samples. It extends the application scope of wavelet method.  

摘要：By using Burnside-Polya enumerating method, principle of inclusion-exclusion and other combinatorial analysis, a class of combinatorial identities for equivalent classes with action of group on set are studied. Some combinatorial identities for enumerations of equivalent classes of a class of mapping under identical transformation group and cycle group and dihedral group actions are obtained. These results generalize some known results.  

摘要：The quantum plasma system is discussed. A nonlinear dynamic disturbed model is studied. Using the undetermined coefficients method for the hyperbolic functions, perturbation theory and method, the solitary wave solution of corresponding model is solved. And the characteristics of corresponding physical quantity are expounded.  

摘要：Under the basic assumptions on generators of backward stochastic differential equations, the one-to-one correspondence between subadditivity (resp. homogeneity) of g-expectations and generators of backward stochastic differential equations is obtained. Thus it is proved that the definitions of dynamic coherent risk measures in Detlefsen-Scandolo (2005) and Jiang (2008) are completely same under the framework of g-expectations. Furthermore, the relationship between time-consistent dynamic coherent risk measures via g-expectations and sublinearity of g-expectations is established.