International Journal of Modern Physics C

One dominant aspect of cities is transport and massive passenger mobilization which remains a challenge with the increasing demand on the public as cities grow. In addition, public transport infrastructure suffers from traffic congestion and deterioration, reducing its efficiency. In this paper, we study the capacity of transport in 33 worldwide metro systems under the accumulation of damage. We explore the gradual reduction of functionality in these systems associated with damage that occurs stochastically. The global transport of each network is modeled as the diffusive movement of Markovian random walkers on networks considering the capacity of transport of each link, where these links are susceptible to damage. Monte Carlo simulations of this process in metro networks show the evolution of the functionality of the system under damage considering all the complexity in the transportation structure. This information allows us to compare and classify the effect of damage in metro systems. Our findings provide a general framework for the characterization of the capacity to maintain the transport under failure in different systems described by networks.

This study recommends a novel structured packing (SP) PACK-860X with a specific surface area of 860m²/m³, which is defined utilizing a numerical method. We attempt to investigate the main properties of PACK-860X for illustration, height equal to a theoretical plate (HETP), dry pressure drop (DPD) and wet pressure drop (WPD). In addition, the flow pattern is expressed for packing through computational simulation. To assess the amounts of HETP, WPD and DPD, the 3D CFD simulation with the Eulerian–Eulerian multi-phase technique is employed in this work. Based on the results of this work, WPD and DPD are improved. According to the data, numerical outcomes are in good agreement with the theoretical results, which shows the reliability of CFD methods for modeling the separation processes.

Dependency links represent the relationships between network nodes that have an interactive impact on cascading failures caused by load fluctuation in the network. However, existing research mainly focuses on load fluctuation’s failure mechanisms without considering the dependency links of nodes and their cascading prevention mechanisms in reality. This study addresses the cascading prevention problem in networks when dependency links and connectivity links operate together. It proposes a hybrid cascading failure model based on the dependency relationships, load fluctuation and reinforced nodes. Furthermore, it provides four reinforced nodes’ strategies that leverage static and local information characteristics of network nodes. These strategies help the network to perform its function and prevent cascading failures effectively. The study considers actual situations where overloaded nodes can still maintain their function. To measure the overload ability and the uncertainty of node failure, the authors used the overload coefficient parameter and the failure probability. Additionally, the impact of the dependency group’s size on the network robustness is explored. Simulation results on BA and ER networks and two actual networks show that reinforced nodes’ strategies provide significant support in keeping the network away from abrupt collapses.

The issue of stochastic fixed-time synchronization (SFxS) between two nonlinear chaotic finance systems (CFSs) in noisy environment is addressed by this investigation. Two novel strategies, including the adaptive and fixed-time control, are integrated organically, which steers the CFSs to realize synchronization within a fixed-time, and meanwhile the controlling gains can be updated by the designed adaptive law. Particularly, the designed adaptive fixed-time controlling (AFC) scheme is differentiable, so that the chattering phenomenon can be alleviated and even eliminated effectively. Furthermore, by the stochastic Lyapunov stability analysis, the sufficient criterion is derived for realizing the SFxS of CFSs, and the upper-bound expectation of settling-time (UET) is estimated as well. At last, the numerical experiments are arranged to verify the correctness and feasibility of analytical results, the influence of noisy perturbation on the convergence rate is uncovered, and the interesting similar Dragon–King events are observed.

The study of traffic dynamics on multi-layer network contributes to revealing the traffic law of the actual network and suppressing the occurrence of network congestion. Focusing on actual network traffic characteristics, we construct a three-layer network model which consists of one logical layer and two physical layers. The traffic dynamics of the three-layer network model are carefully compared with different logical layer routing strategies. In addition, three indicators of load average, load standard deviation and load reduction rate are proposed to more intuitively observe the load conditions of physical layer nodes. We also study the impact of the degree distribution of physical layer on traffic capacity of three-layer network. It is found that when the preference of packets selection for small degree nodes is insufficient or excessive, it is not conducive to achieving higher traffic capacity.

The theoretical and applied research on hypergraph or hypernetwork is one of the hot topics of system science. Spanning hypertree extended from spanning tree is an interesting problem about this topic, but determining the number of spanning hypertrees in general hypergraphs is not suitable for generalizing from graph and more intractable. In this paper, we propose a definition of spanning hypertree which has less constraints than the traditional definition of spanning hypertree, and then find exact analytical expressions for the number of spanning hypertrees in several kinds of non-uniform hypergraphs based on sum operation. In addition, we define the entropy of spanning hypertree and conduct data experiments on the entropies of spanning hypertrees in four special classes of non-uniform hypergraphs.

In this paper, we statistically analyze the density of each chess piece in four square concentric frames for different skill levels (according to the Elo ranking system), phases (opening, middlegame and endgame) and outcomes. The results indicate a tendency for pawns, knights and bishops to move towards the central areas, particularly during the opening phase. Additionally, we identified intrinsic entropy patterns for each piece throughout the entire game, independent of player skill level. We constructed a phase-space from entropy delay time series to provide probabilistic predictions for game outcomes.

In this analysis, the stability of MHD stagnation point flow and heat transfer of an electrically conducting viscous incompressible fluid on a horizontally stretching/shrinking permeable cylinder with volumetric heat source are investigated. The cylindrical surface is subjected to a cross flow and a heat flux. This analysis finds applications in the areas of polymeric processing unit due to stretching/shrinking of surface and biofluid flows with therapeutic effects through the arteries, vein and digestive system that have a tube-like structure. Other aspects of the analysis are: magnetic field intensity whose strength can be remotely controlled and embodied generating/absorbing thermal power. The solution of the boundary value problems (BVP) is carried out with MATLAB’s inbuilt solver bvp4c. The most significant findings are recorded as: an increase in magnetic field strength increases the skin friction at the solid surface which is consistent with progressive thinning of boundary layer. This striking result is of interest in industrial applications because it is easy to regulate the magnetic field strength by electromagnetic devices such as controlling the voltage in the electric circuit. There is a point of neutrality of thermal energy distribution during the high fluctuation of temperature irrespective of the presence of heat generation or absorption. This can be attributed to the dominating effect of stretching/shrinking of the surface. The first solution provides stability of the flow with an increase in velocity in the presence of heat sink that is commensurate with the strength.

This paper introduces a novel hybrid numerical method, SAUSM, designed for accurate and robust simulation of compressible flows governed by the Euler equations. While the AUSM$+$ scheme provides proper resolution of smooth flow features, it is susceptible to anomalies, particularly the carbuncle phenomenon near strong shock discontinuities. Conversely, the AUFS scheme offers inherent stability in capturing shocks; however, it lacks the accuracy of AUSM$+$ in smooth regions. The proposed SAUSM method combines AUSM$+$ and AUFS through an adaptive weighting function, facilitating a seamless transition between the schemes. This approach preserves the accuracy of AUSM$+$ in smooth regions while ensuring robust shock-capturing capabilities near discontinuities. The effectiveness of the SAUSM method is rigorously demonstrated through a comprehensive suite of progressively complex test cases. Numerical experiments demonstrate SAUSM’s proficiency in resolving intense shock patterns and discontinuities without introducing anomalies. In the selected test cases, SAUSM agrees with reference solutions and effectively mitigates anomalies observed in AUSM$+$, including kinked Mach stems. In the challenging test case involving hypersonic blunt body flow over a cylinder, SAUSM adapts dissipation effectively by utilizing its adaptive weighting function to generate smooth pressure distributions, thereby eliminating the carbuncle instability linked to AUSM$+$ when applied to a high aspect ratio grid. The consistent formulation of flux splitting and the adaptive weighting in SAUSM prevent excessive dissipation away from discontinuities, thus preserving accuracy comparable to that of exact Riemann solvers. Consequently, SAUSM emerges as a promising and innovative approach to accurately and robustly simulate a wide range of compressible Euler flows. The comprehensive results obtained from the validation tests firmly establish SAUSM as a highly effective general-purpose technique for computational fluid dynamics in academic research.

To investigate the spread of cascading failure on dual-layer networks, we propose a dual-layer network model based on eigenvector centrality and define network interactions through different connection strategies. Following the local priority reallocation rule of load and the nonlinear relationship between load and capacity, we conduct theoretical analysis of the proposed model and simulate it on the BA scale-free network. The result simulation shows that under different connection strategies, when the controllable coefficient $\alpha =0.6$ of the initial load, the dual-layer network demonstrates better robustness regardless of attacking a node with a large initial load or a small initial load. And when $\alpha <0.6$, the robustness of the network for attacking a node with low initial load is enhanced as the node coupling rate of the dual-layer network increases. For $\alpha \ge 0.6$, the variation of network robustness does not vary essentially with the node coupling rate.

The existing conventional vehicle transportation landscape in India is grappling with challenges stemming from extensive air pollution, health risks, surging oil prices, limited fossil fuel resources, substantial oil import expenses and energy volatility. To counter these issues, Electric Vehicles (EVs) are progressively replacing internal combustion engines, offering a promising route toward decarbonization and mitigating climate concerns. EVs rely on electric motors powered by batteries, predominantly Lithium-ion batteries (LIBs), known for their superior attributes such as low self-discharge, high energy density and extended life cycle. Nevertheless, LIB performance is significantly influenced by operating temperatures, with suboptimal conditions leading to decreased efficiency, power loss and faster aging. Addressing this, an effective Battery Thermal Management System (BTMS) becomes crucial to maintain batteries at optimal temperatures, enhancing their efficiency and safety. This study focuses on a computational analysis of passive heating systems employing Fins and Phase Change Materials (PCM) for 18650 Li-ion battery thermal management at low temperatures, with specific attention to battery module analysis. Numerical analysis using ANSYS FLUENT investigates the influence of varying PCM thickness on heat transfer, predicting temperature distribution and discussing its impact on battery output performance.

Gravity currents modify their flow characteristics in the presence of an obstacle. Also, the flow path to the dam reservoirs is not always direct. Since no studies have addressed the feedback between the hydrodynamics of a gravity current in a curved channel and the location effects of the obstacle, in this research, a Lock-exchange density current flows in a 120${}^{\circ }$ bending channel. The numerical simulation has been performed using OpenFOAM software. The models include no-obstacle curved channel and a curved channel with an obstacle in different positions concerning the increased radius of the curved channel. Results indicated that the obstacle directed the concentration towards the banks, with its maximum value tending from the outer to the inner bank, especially in the tail. The tail longitudinal velocity maximized near the channel bed in areas far from the obstacle, and in the outer bank in areas near it. The secondary flow reduces its lowest and most different pattern observed around the obstacle. In displacing the latter, if the front has at a certain distance, the secondary flow does not change much, but if it has at the channel end, the post-obstacle secondary flow would increase as the obstacle neared the Lock.

In this work, the dynamic motion of a particle in an incompressible Newtonian fluid flow is investigated analytically. The shear and rotation effects on the lift and drag forces of the particle are considered for this problem. Also, the equations governing the motion of a particle are solved using the Temimi–Ansari technique. Analytical solutions for the horizontal and vertical velocities of this particle are obtained and analyzed in terms of time. The corresponding analytical findings are verified in comparison with numerical solutions. The obtained results showed very good accuracy of the solutions and the efficiency of this method in the whole time domain by employing the Padé approximation.

The recently introduced Theory of the Adjacent Possible (TAP) is a model of combinatorial innovation aiming to explain the “hockey-stick” upward trend of human technological evolution, where an explosion in the number of produced items with increasing complexity suddenly occurs. In addition, the TAP model was also used to explain the rapidly emerging biological complexity. Inspired by TAP here we propose a reaction–diffusion system aiming to extend the model in both space and time. We show that the new model exhibits similar characteristics to the TAP model, like the sudden increase in the production of items, after a longer period of slow growth. The new model also exhibits wave propagation of “innovation”, resulting in self-sustained complex interference patterns.