ANALYSIS OF CONTACT FRICTION BEHAVIOR IN THE BENDING PROCESS OF SEMI-PARALLEL STEEL WIRE CABLE

In the bending process of semi-parallel steel wire cable, with the increase of the lateral displacement of the bending, the interaction between the steel wires in the cable is remarkable and the mechanical behavior is complicated. In order to study the mechanical behavior of the contact friction between the inner steel wires in the process of cable bending, this paper uses the 37-φ7 semi-parallel steel wire as the research object, and uses the ANSYS to set up the finite element model of the cable bending, and verifies the correctness of the refined finite element model by bending test data. Based on the refined finite element model of the test data verification, the variation rule of the contact friction between the inner steel wires in the semi-parallel steel wire of different boundary conditions in the bending process is studied, and the axial sliding behavior of the steel wires in the cable bending process is analyzed. The results show that the bending and mechanical properties of the semi-parallel steel wire cable can be calculated more accurately by considering the refined finite element model of the contact friction, and the amount of deformation between the steel wires during the bending process of the semi-parallel steel wire cable can be calculated. The contact pressure and the contact friction stress are non-linear with the increase of the lateral displacement of the bending, and there is a maximum value for the contact friction stress for the pre-tension semi-parallel wire cable, and the maximum position of the axial accumulated slip amount between the steel wires is located at the bending cable section of the calculated span of 1/4 or 3/4 times

Ciliary parathyroid hormone signaling activates transforming growth factor-β to maintain intervertebral disc homeostasis during aging

© 2018 The Author(s). Degenerative disc disease (DDD) is associated with intervertebral disc degeneration of spinal instability. Here, we report that the cilia of nucleus pulposus (NP) cells mediate mechanotransduction to maintain anabolic activity in the discs. We found that mechanical stress promotes transport of parathyroid hormone 1 receptor (PTH1R) to the cilia and enhances parathyroid hormone (PTH) signaling in NP cells. PTH induces transcription of integrin αvβ6 to activate the transforming growth factor (TGF)-β-connective tissue growth factor (CCN2)-matrix proteins signaling cascade. Intermittent injection of PTH (iPTH) effectively attenuates disc degeneration of aged mice by direct signaling through NP cells, specifically improving intervertebral disc height and volume by increasing levels of TGF-β activity, CCN2, and aggrecan. PTH1R is expressed in both mouse and human NP cells. Importantly, knockout PTH1R or cilia in the NP cells results in significant disc degeneration and blunts the effect of PTH on attenuation of aged discs. Thus, mechanical stress-induced transport of PTH1R to the cilia enhances PTH signaling, which helps maintain intervertebral disc homeostasis, particularly during aging, indicating therapeutic potential of iPTH for DDD

Bayesian network variable elimination method optimal elimination order construction

Variable Elimination (VE) is the most basic one of many Bayesian network inference algorithms. The speed and complexity of reasoning mainly depend on the order of elimination. Finding the optimal elimination order is a Nondeterministic Polynomial Hard (NP-Hard) problem, which is often solved by heuristic search in practice. In order to improve the speed of reasoning of the variable elimination method, the minimum, maximum potential, minimum missing edge and minimum added complexity search methods are studied. The Asian network is taken as an example to analyze and calculate the complexity and elimination of the above search method. Meta-order, through MATLAB R2018a, the above different search methods were constructed and reasoned separately. Finally, the performance of the four search methods was compared by inference time analysis. The experimental results show that the minimum increase complexity search method is better than other search methods, and the average time consuming is at least 0.012s, which can speed up the reasoning process of Bayesian network

An Automated Method for Extracting Rivers and Lakes from Landsat Imagery

The water index (WI) is designed to highlight inland water bodies in remotely sensed imagery. The application of WI for water body mapping is mainly based on the thresholding method. However, there are three primary difficulties with this method: (1) inefficient identification of mixed water pixels; (2) confusion of water bodies with background noise; and (3) variation in the threshold values according to the location and time of image acquisitions. Considering that mixed water pixels usually appear in narrow rivers or shallow water at the edge of lakes or wide rivers, an automated method is proposed for extracting rivers and lakes by combining the WI with digital image processing techniques to address the above issues. The data sources are the Landsat TM (Thematic Mapper) and ETM+ (Enhanced Thematic Mapper Plus) images for three representative areas in China. The results were compared with those from existing thresholding methods. The robustness of the new method in combination with different WIs is also assessed. Several metrics, which include the Kappa coefficient, omission and commission errors, edge position accuracy and completeness, were calculated to assess the method’s performance. The new method generally outperformed the thresholding methods, although the degree of improvement varied among WIs. The advantages and limitations of the proposed method are also discussed

Absolute velocity effect for network of SPA systems coupled by predator-prey relationship.

<p>(a) Optimal synchronization <i>V</i>_<i>so</i> as a function of the absolute velocity <i>v</i>_<i>o</i> for each subsystem and the entire system. (b) Optimal coupling strength <i>β</i>_<i>o</i> as a function of the absolute velocity <i>v</i>₀ for each subsystem and the entire system. The simulation results are saved in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144153#pone.0144153.s005" target="_blank">S5 File</a>.</p

System size effect for SPA systems coupled by symbiotic relationship.

<p>(a) Synchronization <i>V</i>_<i>α</i> as a function of the coupling strength <i>β</i> under different system size <i>n</i> of two subsystems, exhibiting that there exists an optimal value of <i>β</i>, when <i>β</i> = <i>β</i>_<i>o</i> the the entire system reaches an optimal synchronization. (b) Optimal synchronization <i>V</i>_<i>so</i> as a function of system size <i>n</i> for subsystem A, subsystem B and the entire system. All the data points are in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144153#pone.0144153.s001" target="_blank">S1 File</a>.</p

Collective Motion in a Network of Self-Propelled Agent Systems

<div><p>Collective motions of animals that move towards the same direction is a conspicuous feature in nature. Such groups of animals are called a self-propelled agent (SPA) systems. Many studies have been focused on the synchronization of isolated SPA systems. In real scenarios, different SPA systems are coupled with each other forming a network of SPA systems. For example, a flock of birds and a school of fish show predator-prey relationships and different groups of birds may compete for food. In this work, we propose a general framework to study the collective motion of coupled self-propelled agent systems. Especially, we study how three different connections between SPA systems: symbiosis, predator-prey, and competition influence the synchronization of the network of SPA systems. We find that a network of SPA systems coupled with symbiosis relationship arrive at a complete synchronization as all its subsystems showing a complete synchronization; a network of SPA systems coupled by predator-prey relationship can not reach a complete synchronization and its subsystems converges to different synchronized directions; and the competitive relationship between SPA systems could increase the synchronization of each SPA systems, while the network of SPA systems coupled by competitive relationships shows an optimal synchronization for small coupling strength, indicating that small competition promotes the synchronization of the entire system.</p></div

Radius effect for predator-prey relationship.

<p>(a) Optimal synchronization <i>V</i>_<i>so</i> as a function of radius <i>R</i> for each subsystem and the entire system. (b) Optimal coupling strength <i>β</i>_<i>o</i> as a function of radius <i>R</i> for each subsystem and the entire system. All the data points are in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144153#pone.0144153.s006" target="_blank">S6 File</a>.</p

Collective Motion in a Network of Self-Propelled Agent Systems - Fig 1

<p>In system A, the position of node <i>w</i> is (<i>x</i>_{<i>A</i>,<i>w</i>},<i>y</i>_{<i>A</i>,<i>w</i>}), and it has 7 neighboring agents within a circle with a radius being <i>R</i> [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144153#pone.0144153.e004" target="_blank">Eq (3)</a>], whose position projecting on system B is also (<i>x</i>_{<i>A</i>,<i>w</i>},<i>y</i>_{<i>A</i>,<i>w</i>}), and it has 4 neighboring agents in system B [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144153#pone.0144153.e005" target="_blank">Eq (4)</a>]. Accordingly, we could identify the neighborhoods of all nodes in both systems.</p