Study on the Electrical Conductivity of Inorganic Conductive Network in Sediments

The inorganic conductive network provides an essential channel for electron transport and supports the biogeochemical process in sediments, but the conductive mechanism of conductive network is not well understood. In this work, theory of circuit and electronics was applied to build a three-dimensional (3D) resistivity network simulation model for exploring the conductive mechanism and analysing the effect of the particle size on the conductive characteristic of inorganic conductive network. In order to simulate the real sediment environment, inorganic composites with silica (SiO2) particles as matrix using magnetite (Fe3O4) particles as fillers are constructed. The simulation results reveal that the electrical conductivity of these composites rises nonlinearly with the increasing volume fraction of conductive fillers, which is consistent with the percolation theory. Moreover, small-sized conductive particles or large-sized matrix particles are confirmed to exert a positive part in enhancing electrical conductivity of composites.

What network simulator questions do users ask? a large-scale study of stack overflow posts

<span>The use of network simulator as a modern tool in analyzing and predicting the behaviour of computer networks has grown to reduce the complexity of its accuracy measurement. This growth of network simulator implementation have attracted the researchers and practitioners to share problems and discuss to improve the features. To communicate the issues relates to network simulators, users move to an online discussion platform, such as Stack Overflow. Although recent studies have shown the popularity and benefits of adopting network simulation tools, however, the challenges of using network simulator that users face remain mostly unknown. Therefore, in this paper, we examine 2,322 network-simulator-related Stack Overflow posts to provide insights on the topics that users are interested and the challenges they face. We apply the Latent Dirichlet Allocation topic modeling to understand the topics that are being discussed in Stack Overflow. Then, we investigate the popularity and difficulty of each topic. The results of this study show that users use Stack Overflow as an implementation guideline for network simulation model. We determine 8 discussion topics that are merged into 5 major categories. Most of the posts discuss simulation model configuration. We also observe that target network protocol modification and network simulator installation are the most popular topics among the users compared to other topics. Users are specially facing challenges on network simulator installation and target network protocol modification issues.</span>

Impact on Myanmar’s Logistics Flow of the East–West and Southern Corridor Development of the Greater Mekong Subregion—A Global Logistics Intermodal Network Simulation

This study focuses on container shipping in Myanmar, which is expected to grow manifold in the near future, given the country’s rapid economic growth rates. This study simulates the impact of Myanmar’s logistics policies on container shipping. These initiatives include the improvement of the East–West Corridor of the Greater Mekong Subregion and the development of the Southern Corridor and Dawei port. The global logistics intermodal network simulation model including both maritime shipping and land transport, is applied to the land-based southeast Asia (ASEAN) region. The estimated results obtained for several different scenarios are crosschecked and compared with the available information on observed flows. Based on the simulation results, the authors conclude that policies that reduce cross-border barriers and improve service levels in Dawei port would result in Thailand using Myanmar’s ports for their cargo as well.

High-Quality Masks Can Reduce Infections and Deaths in the US

Objectives: To evaluate the effectiveness of widespread adoption of masks or face coverings to reduce community transmission of the SARS-CoV-2 virus that causes Covid-19. Methods: We employed an agent-based stochastic network simulation model, where Covid-19 progresses across census tracts according to a variant of SEIR. We considered a mask order that was initiated 3.5 months after the first confirmed Covid-19 case. We evaluated scenarios where wearing a mask reduces transmission and susceptibility by 50% or 80%; an individual wears a mask with a probability of 0%, 20%, 40%, 60%, 80%, or 100%. Results: If 60% of the population wears masks that are 50% effective, this decreases the cumulative infection attack rate (CAR) by 25%, the peak prevalence by 51%, and the population mortality by 25%. If 100% of people wear masks (or 60% wear masks that are 80% effective), this decreases the CAR by 38%, the peak prevalence by 67%, and the population mortality by 40%. Conclusions: After community transmission is present, masks can significantly reduce infections.

Ranking the critical sections of railway networks

Railway systems are now facing an increasing number of threats such as aging infrastructures and climate changes. The identification of critical network sections provides infrastructure managers with the ability to understand the impact of a disruption and creates a suitable preventive strategy to counter such threats. To this end, various vulnerability analysis methods have been proposed for railway networks. Two main types of methods, network topological analysis and network flow-based analysis, have been developed. Both approaches are constructed based on macroscopic models, which take only some railway properties such as network structure, train and passenger flow into account. Thus, the results obtained are high level approximations. This study proposes a new analysis method, which is developed based on the stochastic-microscopic railway network simulation model. The method can be applied to identify the critical sections of a railway network. The effect of impact levels and occurrence times of a disruption on the network section criticality is presented. An application of the proposed model is demonstrated using the Liverpool railway network in the UK.