Critical behavior of a stochastic anisotropic Bak-Sneppen model

In this paper we present our study on the critical behavior of a stochastic anisotropic Bak-Sneppen (saBS) model, in which a parameter $\alpha$ is introduced to describe the interaction strength among nearest species. We estimate the threshold fitness $f_c$ and the critical exponent $\tau_r$ by numerically integrating a master equation for the distribution of avalanche spatial sizes. Other critical exponents are then evaluated from previously known scaling relations. The numerical results are in good agreement with the counterparts yielded by the Monte Carlo simulations. Our results indicate that all saBS models with nonzero interaction strength exhibit self-organized criticality, and fall into the same universality class, by sharing the universal critical exponents.Comment: 9 pages, 7 figures. arXiv admin note: text overlap with arXiv:cond-mat/9803068 by other author

The Discussion on Construction Engineering Technology on Ultra High-rise Building

oai:ojs.wcj.usp-pl.com:article/23With the speeding up of urbanization and increasing of urban population, the urban land resources are increasingly scarce. Emergence of ultra high-rise building is an inevitable trend. At present, our construction industry is in the rapid development period, where the proportion of ultra high-rise buildings in urban architecture of many big cities constantly increases. The improving ultra high-rise engineering technology is an important part of the construction industry in our country. This paper will analyze the ultra high-rise construction technology of building work in detail

Community detection by label propagation with compression of flow

The label propagation algorithm (LPA) has been proved to be a fast and effective method for detecting communities in large complex networks. However, its performance is subject to the non-stable and trivial solutions of the problem. In this paper, we propose a modified label propagation algorithm LPAf to efficiently detect community structures in networks. Instead of the majority voting rule of the basic LPA, LPAf updates the label of a node by considering the compression of a description of random walks on a network. A multi-step greedy agglomerative strategy is employed to enable LPAf to escape the local optimum. Furthermore, an incomplete update condition is also adopted to speed up the convergence. Experimental results on both synthetic and real-world networks confirm the effectiveness of our algorithm

Prediction Of Nonlinear Vertical Settlement Of A Pile Group Consisting Of New And Existing Displacement Piles In Clay Strata

Reusing existing displacement piles is economical, timesaving, and environment friendly. This paper presents an analytical approach for predicting the load carrying behavior of pile groups consisting of new and existing displacement piles. The evolutions of the undrained shear strength and shear modulus of clay adjacent to the piles from installation through consolidation to long-term ageing are investigated to determine the load carrying behavior of displacement piles. The nonlinear load-settlement behavior of an individual pile is modelled by load-transfer method, where the exponential function-based load-transfer models integrating the two developed soil parameters are employed to represent the nonlinear behavior at the pile-soil interface. The pile-pile interaction in the pile group is explored based on the shear displacement method. Combining the load-transfer method and the shear displacement method, an analytical framework is proposed for predicting the load-settlement behavior of pile groups consisting of new and existing piles. The proposed framework is validated by predicting the vertical settlement of a high-rise apartment built on a pile group consisting of 74 new displacement piles and 22 existing displacement piles during construction. Good agreement is achieved between the predicted and measured results. A parametric study is performed to explore the stiffness efficiency and the load-settlement behavior of pile groups with different layouts of new and existing piles. The results indicate that the pile group with larger ratio of the number of existing piles to the number of total piles shows both stronger stiffness and a higher load carrying capacity

Service Life Of Prestressed High-strength Concrete Pile In Marine Environment Considering Effects Of Concrete Stratification And Temperature

Prestressed high-strength concrete (PHC) piles have advantages of light weight and high load carrying capacity, which have been widely applied in coastal and offshore engineering. However, PHC piles serving in the coastal or offshore regions have already undergone severe durability problem. This paper presents a comprehensive method for predicting the service life of PHC piles in the marine environment, which reasonably takes the temperature effects and the concrete stratification caused by centrifugation of PHC piles into account. The pile service life is divided into the diffusion and corrosion periods. The service life of the diffusion period is predicted by solving the diffusion equation formulated for chloride ion diffusion in a two-layer ring medium, the results of which are compared with the data obtained from the elaborate experimental tests to examine the validity. The service life of the corrosion period is determined based on the ultimate corrosion expansion pressure produced by the accumulated corrosion products of steel bar. Various possible key factors, like protective cover thickness, initial chloride ion concentration, mortar layer thickness, etc., are considered to investigate how these parameters critically affect the pile service life. The results suggest that increasing mortar layer thickness can lead to a significant decrease of the service life in both diffusion and corrosion periods; and increasing protective cover thickness and sealing pile end are two effective ways to extend the service life of PHC piles

Prediction On Service Life Of Concrete Pipeline Buried In Chlorinated Environment Under Nonuniformly Distributed Earth Pressure

This paper proposes an analytical model to estimate the service life of concrete pipelines buried in chloride contaminated soils, which properly considers the effects of nonuniformly distributed earth pressures on both the internal tensile stress of concrete protective cover and the chloride diffusion coefficient through the nonhomogeneous coefficient of earth pressure. It is assumed that the underground concrete pipeline arrives at the service life end when cracking induced by expansion pressure due to the corrosion products occurs in the concrete protective cover. Hence, the whole service life of underground concrete pipeline is composed of chloride diffusion period and protective cover corrosion period. The diffusion of chloride ions is simulated through a diffusion model for dual compound media and the service life of this period is evaluated by solving the diffusion equation. The service life of corrosion period is estimated based on the corrosion expansion pressure with the aid of the concrete tensile strength. The validity of chloride diffusion model is examined through the comparison between the present analytical analysis and the numerical analysis from finite element simulations, guaranteeing that there are reliable results available for the subsequent analysis of corrosion period. Comprehensive parametric studies are conducted to explore the effects of nonuniformly distributed earth pressures and concrete cover thickness on the pipeline service life. The results demonstrate that the nonuniformly distributed earth pressures lead to the occurrence of tensile stress in the protective cover and give rise to the increase in the chloride diffusion coefficient, which in fact accelerates the diffusion of chloride ions in the concrete pipeline and induces the cracking of concrete protective cover and thus significantly shortens the service life of concrete pipelines buried in chlorinated environment

Community Detection in Dynamic Networks via Adaptive Label Propagation

An adaptive label propagation algorithm (ALPA) is proposed to detect and monitor communities in dynamic networks. Unlike the traditional methods by re-computing the whole community decomposition after each modification of the network, ALPA takes into account the information of historical communities and updates its solution according to the network modifications via a local label propagation process, which generally affects only a small portion of the network. This makes it respond to network changes at low computational cost. The effectiveness of ALPA has been tested on both synthetic and real-world networks, which shows that it can successfully identify and track dynamic communities. Moreover, ALPA could detect communities with high quality and accuracy compared to other methods. Therefore, being low-complexity and parameter-free, ALPA is a scalable and promising solution for some real-world applications of community detection in dynamic networks.Comment: 16 pages, 11 figure

The effects of overtaking strategy in the Nagel-Schreckenberg model

Based on the Nagel-Schreckenberg (NS) model with periodic boundary conditions, we proposed the NSOS model by adding the overtaking strategy (OS). In our model, overtaking vehicles are randomly selected with probability $q$ at each time step, and the successful overtaking is determined by their velocities. We observed that (i) traffic jams still occur in the NSOS model; (ii) OS increases the traffic flow in the regime where the densities exceed the maximum flow density. We also studied the phase transition (from free flow phase to jammed phase) of the NSOS model by analyzing the overtaking success rate, order parameter, relaxation time and correlation function, respectively. It was shown that the NSOS model differs from the NS model mainly in the jammed regime, and the influence of OS on the transition density is dominated by the braking probability $p$Comment: 9 pages, 20 figures, to be published in The European Physical Journal B (EPJB

Effects Of Clay Creep On Long-Term Load-Carrying Behaviors Of Bored Piles: Aiming At Reusing Existing Bored Piles

An analytical procedure is presented for assessing the long-term load-carrying behavior of bored piles in clay, where the plastic volumetric strain of surrounding clay caused by creep is estimated by an advanced elasto-viscoplastic constitutive model. Two key soil parameters, the undrained shear strength and the shear modulus, which govern the load-carrying behavior of bored piles in clay, are determined from the definition of the quasi-over consolidation ratio and the concept of the critical state theory-based Cam-clay model. The long-term load-carrying capacity of bored piles is evaluated based on the total stress method. Hyperbolic load-transfer models are developed with proper incorporation of the two developed soil parameters to predict the long-term load-settlement behaviors of the bored pile. The proposed framework is validated by predicting a pile field test on an existing bored pile (about 30 years) in clay, which was recently performed by the authors in Pudong New Area, Shanghai, and field static load tests on two single bored piles conducted by other researchers. Comprehensive parametric studies are conducted to explore the effects of secondary compression index and in situ soil properties on long-term load-carrying behavior of bored piles. The proposed procedure is expected to provide useful guidance for estimating the load-carrying behavior of existing bored piles in clay and take the ultimate aim of reusing them in practice