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In this paper, we consider a predator-prey system with two time delays, which describes a prey–predator model with parental care for predators. The local stability of the positive equilibrium is analysed. By choosing the two time delays as the bifurcation parameter, the existence of Hopf bifurcation is studied. Numerical simulations show the positive equilibrium loses its stability via the Hopf bifurcation when the time delay increases beyond a threshold.

With the expansion of China's power grid, the scale, transmission distance and load capacity of transmission projects are all growing rapidly. Meanwhile, the problem of transmission line running state detection is also attracting more and more attention. Electric field under high voltage transmission line is taken as the research object in this paper, and the principle of electric field inverse operation is analyzed, two kinds of calculation objects and methods of nondestructive examination are are described in detail. There are two kinds of intelligent algorithms in this paper in order to solve the problem of several unknown solutions in inverse electric field operation. Correspondingly, the fitness function based on voltage value and result value is established, and the inverse electric field operation algorithm with global optimization function is proposed. A calculation example of high-voltage transmission line is also used to verify the inverse problem optimization algorithm. It is respectively proved by calculation results that the effectiveness and accuracy of the optimization method based on the two kinds of intelligent algorithms.

With the development of “One Belt, One Road” initiative and free trade area, the volume of cross-border international logistics involving multiple modes of transport has surged. Meanwhile, the proportion of using integrated transportation system in domestic trunk transport has increased. Multi-modal transport (MMT) based on green transport can realize intensive utilization of transport capacity resources, and implement sustainable transport management with three bottom lines of economic, environmental and social aspects. In this paper, the carbon emission index and regional transportation infrastructure utilization index are introduced to construct a multi-objective optimization model with sustainable goals of environmental protection, cost saving and social contribution. The poly-population genetic algorithm (PPGA) is used to overcome the limitation of the traditional genetic algorithm running to the local optimum. The model proposed by this paper quantifies environmental and social indicators, balances comprehensive performance of environment, economy and society, and provides quantitative decision making support for carriers, international freight forwarder or third party logistics to carry out green MMT.

This article is the product of a long-term relationship between Prof. Yang Shengmin (Minzu University of China) and Prof. Roberto Malighetti (University of Milano-Bicocca). It is the outcome of a scientific collaboration that started in 2012 in Beijing, continued with the conference Anthropologies From in China. The First Italian Conference (University of Milano-Bicocca, 13.12. 2013), and was consolidated by the didactic activities at the Minzu University of China. It took the present form in the course of a conversation in the offices of the Collaborative Innovation Center for Ethnic Minority Development (Minzu University, Beijing) on the 6th of June 2016. Transcribed and then revised by both authors, the text considers the importance of Chinese anthropology and its contribution to the international dialogue. It probes the possibilities open to Chinese anthropology to offer an original articulation of its tradition with the Western influences that accompanied, from the very beginning, the development of anthropology in China. The Chinese innovative proposals are synthetized under three approaches: the historical, the Marxist, the applied, and the study of minorities.

Currently, tight carbonate gas reservoir has received little attention due to few discoveries of them. In this study, gas–water two-phase relative permeability was measured under two different conditions: High Temperature High Pore Pressure (HTHPP – 80 °C, 38 MPa), as well as Ambient Condition (AC), using whole core samples of tight gas carbonate. Relative permeability curves obtained at HTHPP showed two contrary curve profiles of gas relative permeability, corresponding to the distinctive micro-pore structure acquired from CT-Scanning. Then, based on Klinkenberg theory and a newly developed slip factor model for tight sandstone, slippage effect under AC is calibrated and the overestimation of gas relative permeability prove up to 41.72%–52.34% in an assumed heterogeneity. In addition, relative permeability curves obtained at HTHPP switch to higher gas saturation compared to that under AC with the rock wettability change from water-wet to less water-wet. And the wettability alteration is believed to be caused by charge change on mineral surface.

In order to quantitatively evaluate the pore-scale formation damage of tight sandstones caused by asphaltene precipitation during CO2 flooding, the coreflood tests and Nuclear Magnetic Resonance (NMR) relaxometry measurements have been designed and applied. Five CO2 coreflood tests at immiscible, near-miscible and miscible conditions were conducted and the characteristics of the produced oil and gas were analyzed. For each coreflood test, the T2 spectrum of the core sample was measured and compared before and after CO2 flooding to determine the asphaltene precipitation distribution in pores. It is found that, the solubility and extraction effect of the CO2 plays a more dominant role in the CO2-EOR (Enhanced Oil Recovery) process with higher injection pressure. And, more light components are extracted and recovered by the CO2 and more heavy components including asphaltene are left in the core sample. Thus, the severity of formation damage influenced by asphaltene precipitation increases as the injection pressure increases. In comparison to micro and small pores (0.1–10 ms), the asphaltene precipitation has a greater influence on the medium and large pores (10–1000 ms) due to the sufficient interaction between the CO2 and crude oil in the medium and large pores. Furthermore, the asphaltene precipitation not only causes pore clogging, but also induces rock wettability to alter towards oil-wet direction.

Objective: To identify key determinants of increased PA level among adults with T2DM to improve a hierarchical model, based on social cognitive theory (SCT) and Ecological Models. It hypothesises and clarifies how these determinants relate to physical activity which is important to evidencebased PA interventions in middle aged and older people with T2DM. Methods: Full transcript studies in English were searched in the following databases: CINAHL, Medline on OvidSP, PubMed, and PsycINFO. Included articles were selected by following these combined terms: type 2 diabetes, physical activity, exercise, physical inactivity, correlates, barriers, theory, self-efficacy, ecological models. And they (n=124) met the following criteria: 1) T2BD, aged 35 and over; 2) reporting determinants or factors 3) indicated physical activity or exercise as an outcome variable. Additional records identified via bibliographies (n=4), duplicates were removed (n=95), non-full-text articles (n=8) and no-English (n=2) were excluded. Finally, of the 21 articles retrieved from databases (9 of them are reviewed studies), only 12 original articles including qualitative and quantitative study were reviewed. Results: The determinants are divided into four classifications; physical, psychological, social and environmental factors, adapted combined SCT with Ecological Model of physical activity with T2MD in middle aged older adults. Self-efficacy is the core mediators with physical, environmental, and social factors, that fact is the core of SCT. Self-efficacy had an indirective negative influence by physical factors particular regions with physical barriers such as cold weather, low-density land use. Therefore, managing self-efficacy is proposed to effectively change for physical activity. It is hypothesised that improve social supports from family may help people with T2DM increase the physical activity level. Conclusion: Therefore, it is evident from the above that many factors of PA in middle aged and older people with T2DM exist. And self-efficacy is an important determinant with PA. There is a need to clarify whether these variables are determinants and the causality between these variables. Nonetheless, theory-basement approach to studying PA in this population is required based upon this study

Magnetic nanoparticles offer many exciting opportunities in biology and biomedicine, such as magnetic resonance imaging, magnetic hyperthermia therapy, biomedical diagnosis. The synthesis of multifunctional magnetic nanocomposites that possess water-solubility, magnetic properties and optical stability by a green method at room temperature in aqueous phase is still an unmet need. Here, we developed a simple and green method for preparing Fe3O4@Au integrated the super-paramagnetic and optical properties by seed-mediated growth at mild condition in aqueous phase. The amphiphilic, non-ionic and nontoxic polymer poly(vinylpyrrolidone) (PVP) was used as a coupling agent for synthesis of Fe3O4@Au nanocomposites, which avoided the direct connection of Au and Fe3O4, and improved the saturation magnetization values of Fe3O4@Au to 40 emu/g at room temperature. We anticipate that the multifunctional Fe3O4@Au nanocomposites with high magnetic and good optical properties will provide a platform for potential diagnostic and therapeutic biomedical applications.

The influences of extrusion speed on the microstructure and tensile properties of AZ31 alloy were investigated. The results suggested that the yield and tensile strength of AZ31 alloy decrease but elongation increases with the reduction of extruded speed. High speed extrusion produces fine grains with texture of c-axis perpendicular with extruded direction. The tension deformation is dominated by slip and the formed texture is obstructive for the basal slip, and also the inhomogeneous structure formed at high speed extrusion is harmful to the ductility. Samples extruded at low speed have comparatively homogeneous and coarse microstructure. Twinning provided more tension deformation and the lattice rotation induced by twinning is favorable for the activities of new slip systems, which induced the better ductility of AZ31 alloy.