Vibration behavior and response to an accidental collision of SFT prototype in Qiandao Lake (China)

AbstractThis article presents free vibration analysis of the submerged floating tunnel (SFT) prototype, which has been designed to be built in Qiandao Lake (China). As an approximation the supporting effect of the tethers is omitted in the calculation of beam-like bending vibrations. As a case study, the response of the SFT prototype to an accidental collision by an object like a sinking boat is examined. The deformation and the stress of the SFT are computed and the safety assessment is given. Finally, by using the plastic hinge model, the energy absorption capacity of the aluminium alveolate layer is estimated

The Effect of Positive Interactions on Temporal Turnover of Community Composition along an Environmental Gradient

Peer reviewe

Direct and indirect effects of climate on richness drive the latitudinal diversity gradient in forest trees

Data accessibility statement: Full census data are available upon reasonable request from the ForestGEO data portal, http://ctfs.si.edu/datarequest/ We thank Margie Mayfield, three anonymous reviewers and Jacob Weiner for constructive comments on the manuscript. This study was financially supported by the National Key R&D Program of China (2017YFC0506100), the National Natural Science Foundation of China (31622014 and 31570426), and the Fundamental Research Funds for the Central Universities (17lgzd24) to CC. XW was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB3103). DS was supported by the Czech Science Foundation (grant no. 16-26369S). Yves Rosseel provided us valuable suggestions on using the lavaan package conducting SEM analyses. Funding and citation information for each forest plot is available in the Supplementary Information Text 1.Peer reviewedPostprin

Causes and Behavioral Evolution of Negative Electronic Word-of-Mouth Communication: Considering the Mediating Role of User Involvement and the Moderating Role of User Self-Construal

The purpose of this study is to develop a framework to examine the intrinsic driving paths of negative electronic word-of-word. In this paper, the “contextual” factor—user involvement, and the “individual” factor—user self-construal were selected to consider their influence on the model path. Data were collected using online questionnaires; then, the model and hypotheses were tested using structured equation model (SEM) software. The research results showed that, firstly, negative online shopping experiences positively influence eWOM motivations, and user involvement partially mediated the relationship between negative product quality, negative online shopping platform environments and negative eWOM motivations; secondly, there was a significant correlation between negative eWOM motivations and eWOM behavior, and the personality traits of the communicators themselves influenced the path of “negative eWOM motivation-negative eWOM behavior”. In addition, the user’s self-construal has a significant moderating effect on the “eWOM motivation–immediate eWOM behavior” path under immediate eWOM behavior

How does functional distinctiveness affect single species contribution to β diversity? Evidence from a subtropical forest plot in southern China

To biologically interpret β diversity patterns, in terms of species characteristics, needs to quantify how each individual species contributes to overall β diversity (SCBD). However, the lack of studies linking SCBD to functional traits hinders to explore the full potential of the approach in biodiversity conservation. Here, we combined census data, species functional traits, and environmental variables from a 50-ha stem-mapped forest plot in southern China, with the aim to disentangle the relationship among SCBD, species functional traits and niche properties. We used nine functional traits to estimate species functional distinctiveness, and eleven environmental variables were used to compute species niche properties (niche position and niche breadth). Structural equation modeling (SEM) was applied to analyze how functional distinctiveness and niche properties jointly influenced SCBD. Results found that species with more unique trait combinations (higher functional distinctiveness) occupied marginal niche position and maintained smaller niche breadths and thus contributed less to overall β diversity. Meanwhile, functional distinctiveness and niche properties jointly determined SCBD. In addition, we found a negative effect of functional distinctiveness on SCBD, which implies the urgency of developing better biodiversity conservation strategies by unravelling the linkage between SCBD and ecosystem multifunctionality. These findings contribute to a better understanding of how species characteristics affect β diversity and making SCBD more applicable in biodiversity conservation

Simulation of complex fracture networks influenced by natural fractures in shale gas reservoir

When hydraulic fractures intersect with natural fractures, the geometry and complexity of a fracture network are determined by the initiation and propagation pattern which is affected by a number of factors. Based on the fracture mechanics, the criterion for initiation and propagation of a fracture was introduced to analyze the tendency of a propagating angle and factors affecting propagating pressure. On this basis, a mathematic model with a complex fracture network was established to investigate how the fracture network form changes with different parameters, including rock mechanics, in-situ stress distribution, fracture properties, and frac treatment parameters. The solving process of this model was accelerated by classifying the calculation nodes on the extending direction of the fracture by equal pressure gradients, and solving the geometrical parameters prior to the iteration fitting flow distribution. With the initiation and propagation criterion as the bases for the propagation of branch fractures, this method decreased the iteration times through eliminating the fitting of the fracture length in conventional 3D fracture simulation. The simulation results indicated that the formation with abundant natural fractures and smaller in-situ stress difference is sufficient conditions for fracture network development. If the pressure in the hydraulic fractures can be kept at a high level by temporary sealing or diversion, the branch fractures will propagate further with minor curvature radius, thus enlarging the reservoir stimulation area. The simulated shape of fracture network can be well matched with the field microseismic mapping in data point range and distribution density, validating the accuracy of this model