Numerical Simulation Analysis of Mechanical Properties on Rock Brittle–Ductility Transformation Under Different Loading Rates

At present, a large number of physical tests and numerical simulations have been carried out to study the effect of confining pressure on rock deformation mechanism, and some achievements have been achieved; however, the mechanism of rock deformation in actual mine engineering needs to be further studied, for example, rock-burst is actually a unilateral unloading process of rock mass, and this process can not be completed by physical test. RFPA3D was used to simulate the brittle–ductility transformation mechanical properties of rock under different confining pressures in this paper. The damage constitutive equation of rock was derived from continuum damage mechanics; the damage coefficients of different rocks were determined based on the numerical results of stress acoustic emission, so the correctness of rock damage constitutive equation was verified. According to the derived brittle–ductility damage equation and the fitting results of ductility cumulative damage data, it was found that the development trend of rock brittleness stage was almost the same, and the extended separation occurred after entering ductility stage. The larger the Poisson’s ratio was, the longer the ductility stage was. The smaller the Poisson’s ratio was, the shorter the ductility stage was, but the larger the bearing capacity was. At the late loading stage, the ductility cumulative damage of rock showed a linear upward trend, the bearing capacity sharply decreased, the rock stability failure occurred, and the ductility damage coefficient increased gradually. The study on the brittle–ductile mechanical properties of rocks can help to deep mine’s rock-burst prediction and prevention and has significant engineering significance

The Study of Soil Fertility Spatial Variation Feature Based on GIS and Data Mining

International audienceStudying on the spatial distribution and variation characteristics of soil fertility by Application of geographical information systems (GIS) and data mining(DM), with the quantitative analysis of spatial variability of soil fertility in complexity, and provide the effective way for simulations which can be closer to the farmland soil fertility variability. At the same time, interpolation method based on the spatial variability of soil can provide different accuracy data for soil database, researching of space fuzzy clustering based on precise fertilization regional fertility space can provide a decision-making basis for spatial variability of soil fertility evaluation, a precise prediction and evaluation of precision agriculture are the indispensable basic information and theoretical basis of the development and implementation of precision agriculture.In this paper, the authors take the national 863 project which in the Yushu City of Jilin province as the survey region. And then get the best prediction method and discuss the different effect of the soil nutrient under spatial interpolation prediction model on the analysis of the soil nutrient space mutation characteristics of the foundation by the GIS technology and the geography statistical method. Finally, we analysis the soil fertility status by using the weighted space fuzzy clustering as well as the soil nutrient of space mutation distribution, so as to provide basis for the study on area space mutation characteristics of cultivated land soil fertility which has an important theoretical and practical effect on the precise fertilization of crop and soil fertility evaluation

Aggregate Keyword Routing in Spatial Database

Due to the proliferation of Location-Based Service and popularity of online geo-tagged web pages, spatial keyword search has attracted significant attention from both academic and industrial communities. In this paper, we study the problem of finding the nearest aggregate point from multiple query points travelling through a set objects described by a given set of keywords, as well as the optimal routes from the query points to the aggregate point. This problem is defined as the Aggregate Keyword Routing (AKR) Query. We devise an exact algorithm to AKR query based on ellipse pruning. Next we propose an efficient approximate algorithm for AKR: Center Based Assignment (CBA). The performance of the proposed algorithms are evaluated with real data, the results demonstrate the efficiency and the effectiveness

Achieving superior dispersion-strengthening effect in an AA5xxx Al-Mg-Mn alloy by mico-alloying

5xxx Al-Mg based alloys are widely applied as non-heat-treatable alloys. In this work, we designed a dispersion-strengthening Al-4Mg-1Mn-0.3Fe-0.2Si-0.2Zr-0.2Cr (wt.%) alloy. By applying ramp heating and 400 °C isothermal aging, a significant dispersion-strengthening effect through the formation of various types of dispersoids was achieved. Detailed scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis revealed the precipitation behaviors of nanoscale Mn-rich dispersoids and Al3Zr nanoparticles during heat treatments. As a result, an increment of 48 MPa in yield strength was obtained compared with the reference 5182 alloy. Meanwhile, the modified alloy shows a good heat resistance at 400 °C with little loss of yield strength until 200 h of heating. This has been attributed to the further precipitation of Al3Zr particles which counteracts the coarsening of Mn-rich dispersoids. Moreover, the addition of peritectic element Cr was found to significantly promote the precipitation of Al6(Mn,Fe,Cr) in dendritic center regions, thus improving their global distribution across dendrite arms. The presence of dense dispersoids can also improve the recrystallization resistance of the deformed alloy during annealing, thus retaining the deformation fiber structure and significantly retarding the recrystallization behavior. This research demonstrates an effective strategy to develop high-performance 5xxx series alloys strengthened via dispersoids

Research on Digital Agricultural Information Resources Sharing Plan Based on Cloud Computing

Part 1: Decision Support Systems, Intelligent Systems and Artificial Intelligence ApplicationsInternational audienceIn order to provide the agricultural works with customized, visual, multi-perspective and multi-level active service, we conduct a research of digital agricultural information resources sharing plan based on cloud computing to integrate and publish the digital agricultural information resources efficiently and timely. Based on cloud computing and virtualization technology, we establish a cloud computing server storage architecture, design deployment of server virtualization service, and present information resource sharing plan, so the users on different network environment could access to digital agricultural information resources at any time. Application examples demonstrate the use of cloud computing technology can provide heterogeneous resource sharing services for all agriculture-related facilities