Structure Of Medium Research Articles

Regulation strategy and analysis of the ultra-low temperature heat and mass transfer capacity of 3He-4He mixture in the mixing chamber of dilution refrigerator

As an important method for achieving millikelvin temperatures, dilution refrigerators (DRs) have been widely utilized in the fields of low-temperature superconductivity, low-temperature measurement, and space exploration. The mixing chamber (MC) uses a 3He-4He mixture as the refrigerant and serves as the cold end of the DR. However, the current research lacks a detailed study of the effect of the structure of porous media on the MC cooling capacity. In this study, the heat and mass transfer model in the MC is established using the finite element method. The model is based on the improved two-fluid model to evaluate its cooling capacity and propose regulation strategies. The reliability of the model is verified through experiments. When the load power stabilizes at 10 μW, the steady-state temperature is 59.6 mK, and the Kapitza thermal resistance significantly affects the cooling process of the MC. Three strategies for regulating Kapitza thermal resistance are provided. First, the optimal porosity of the sintering cylinder for the porous medium is ε = 0.5. Second, the extreme point of the sintering cylinder is at a height of h = 1.75 cm, and the cooling capacity is at its minimum at this location. Third, the steady-state temperature initially increases and then decreases with an increase in the cylinder radius. This study is of great significance as it reveals the influence of a porous medium heat exchanger on the heat and mass transfer process of mixtures at ultra-low temperatures, guiding the design of DR.

Effects of microscopic pore-throat structure on gas–liquid relative permeability: Porous media construction and pore-scale simulation

The porous media structure of the oil/gas reservoir changes greatly after long-term development, which subsequently influences the macroscopic relative permeability. To clarify the effects of microscopic pore-throat structure on macroscopic relative permeability, we first proposed a method to generate two-dimensional porous media images with adjustable structure parameters. The method is based on Delaunay triangulation and is similar to the pore-network generation process, which can provide binary images for direct numerical simulation of flow through porous media. Then, we established the single component multiphase Shan–Chen lattice Boltzmann method coupling the real gas equation of state. Finally, we discussed the effect of pore radius, coordination number, pore-throat ratio, pore shape, and wettability on the gas–liquid relative permeability curve using the lattice Boltzmann simulation. This study provides an effective method to generate porous media and explain the mechanism of relative permeability change at the pore scale.

Lattice Boltzmann simulation of dissolution patterns in porous media: Single porosity versus dual porosity media

Understanding the influence of porous media structure, particularly dual porosity, on solvent transport and pore geometry evolution during chemical reactions is a complex and critical area of study. This research leverages the lattice Boltzmann method to investigate how the presence of aggregates in a medium affects solvent transport and pore space development, focusing on distinct dissolution regimes: face and wormhole dissolution. The study addresses the challenge of managing variable pore sizes in dual porosity media by developing specialized GPU algorithms, which efficiently handle fine grids and complex pore spaces. The findings reveal that dual porosity significantly enhances dissolution rates in both the face and wormhole dissolution regimes. Intriguingly, while the pattern of face dissolution remains largely unchanged, dual porosity markedly alters the pattern of wormhole dissolution. In dual-porosity media, the wormholes tend to be narrower and more elongated compared to the wider wormholes observed in single-porosity media. This variation is attributed to the reaction area dynamics, where the reduced reactive surface area along the main wormhole path in dual-porosity media results in less solvent engagement in the reaction processes. Moreover, the research provides insights into the microscale interactions in porous media, emphasizing how variations in microscale porosity can have substantial impacts on the overall dissolution dynamics. The study results are not only significant for understanding the fundamental aspects of chemical dissolution in porous media but also have practical implications in fields such as geo-energy and groundwater remediation. These findings help optimizing reaction processes in complex and heterogeneous porous systems, highlighting the need for detailed consideration of microstructural characteristics in modeling and industrial applications.

On a Potential Paradox of a Public Service Internet

Digital capitalism undermines deliberative democracy. This is the diagnosis arrived at by The Public Service Media and Public Service Internet Manifesto (2021), edited by Christian Fuchs and Klaus Unterberger, and Jürgen Habermas’ A New Structural Transformation of the Public Sphere and Deliberative Politics (2023). They condemn the commercial Internet as a deformation of the public sphere and conclude that it needs to be fundamentally restructured. Interestingly, both texts propose to restructure it after the template of broadcasting media. We seek to challenge this approach from a media-political perspective, arguing that it revives an elapsed version of democracy by rekindling the mass media paradigm to which it was bound. Both texts are implicitly based on the assumption that a technology that emerged in capitalism can be used for different, even contradictory, purposes. But what if the media structure of digital communication, irrespective of who owns or controls it, denies its democratic instrumentalisation?

Pore scale numerical simulation of flow and heat transfer non-equilibrium in randomly packed bed

The complex pore structure of porous media in packed beds leads to randomness and non-uniformity of flow and heat transfer. In this paper, the pore-scale method is used to numerically study the flow and heat transfer in 3D randomly packed bed. The average value and root-mean-square (RMS) of variables are used to evaluate the non-equilibrium characteristics of temperature and velocity. The results demonstrate that the packed bed consistently exhibits non-equilibrium phenomena due to the influence of porous media structure. The peak of thermal non-equilibrium occurs at the location with the largest temperature difference between gas and solid phases, while the peak of flow non-equilibrium occurs after reaching maximum temperature. With increasing inlet velocity, there is an expansion in both local velocity and temperature disturbance range, leading to a wider non-equilibrium region. However, the trend of non-equilibrium between flow and heat transfer is different.

Практики телевизионного медиавоспитания семейных ценностей в Китайской Народной Республике

The aim of the research is to summarize the Chinese experience in popularizing family values through media education to study the possibility of extrapolating the ideas, content and structure of Chinese television media in domestic conditions. The paper presents an analysis of Chinese television programs aimed at mainstreaming family values. The content of Chinese television programs on family topics is described and typologized according to the relayed value categories of parenthood, kinship, marriage, neighborhood and joint households presented in the studies. The scientific novelty of the paper lies in the fact that it is the first to specify the content of media education of family values based on Chinese television programs about the family. The sociocultural specifics and dominant family values of Chinese television programs are determined. As a result, it was revealed that the largest number of programs on central and regional television channels, as well as the main Internet broadcasting channels, are aimed at developing the values of parenthood, kinship and marriage among the viewing audience, which is due to the social order of society and the state policy of the PRC. Family-oriented television content provides relatively controlled socialization of members of society through familiarization with the values of family life in modern sociocultural conditions of China, determined by the increasing importance of large families, filial piety, responsible parenthood, marital relationships and personal development in the family.

Bioclogging effects on mass transport using volume averaging method in bioretention cell treating wastewater: Theories

AbstractIn bioretention cell (BRC) systems, internal clogging in the hydraulic field caused by microbial organisms growing in the nonuniform porous media can lead to the reduction of denitrification capacity. To investigate microbial effect processes, a multispecies biological field‐hydraulic coupling transport model in BRC was developed based on the average volume method (AVM) and traditional convection‐diffusion–reaction equation. This model provides a method to establish a connection between the microscale biofilm thickness and the macroscale measurement of pollutant concentration, which has been less frequently discussed in previous research. The present work differs from earlier works by explicitly smoothing the diversity and complexity of media structure by upscaling the physical quantities using the AVM. The results suggest that the model is derived for enhancing a more comprehensive understanding the relationship between the microscopic biofilm thickness and the measured concentration. It is also found that the infiltration description is required adding porosity parameter in order to have an accurate simulation of permeable phenomena under biologically growing condition.

Tapping on Collective National Trauma

Tapping on Collective National Trauma

A novel micro-scale structure reconstruction approach for porous media and characterization analysis: An application in ceramics-based diesel particulate filter

Diesel particulate filter (DPF) made from cordierite with a porous filter media structure has become an essential component in diesel engines to meet the increasingly the strict emission standards. Hence, a more accurate and universal DPF porous filter media model is necessary to analyze the complex mechanism and optimize its performance. In this work, a new optimization method was proposed for the initial DPF model constructed by the quartet structure generation set (QSGS), and the fractal and spectral dimension were used to quantify the actual effects of the optimized DPF model. Results showed that the method could effectively repair dead zones and eliminate burr boundaries, thus decreasing the complexity of the pore structure and increasing the effective flow area of the DPF model. The increase in porosity decreased the fractal dimension and increased the spectral dimension in porous media. Additionally, simulation results showed that the proposed method was more effective on burr boundaries. This allows the optimization method to be adopted more effectively in porous media modeling and provides improved guidance for optimization. Not only DPF, the proposed method offers a new idea for the structure optimization of porous filter media.

Volume Structure Retrieval Using Drone-Based SAR Interferometry with Wide Fractional Bandwidth

Synthetic aperture radar (SAR) interferometry (InSAR) is a well-established remote sensing technique capable of providing accurate topographic information of an area. Multiple scattering occurring at different heights within a single resolution cell, however, cannot be resolved using a single baseline and results in a degradation of the height accuracy. Techniques such as polarimetric InSAR and SAR tomography tackle this problem using additional measurements to obtain the three-dimensional structure of the volume. However, polarimetry-based methods assume orthogonal and deterministic scattering mechanisms and tomography requires numerous observations. This paper presents a novel approach to retrieving the three-dimensional structure of semitransparent media using wide fractional bandwidth InSAR. The frequency dependency of the InSAR coherence is exploited to retrieve the three-dimensional structure, assuming that signals with wide fractional bandwidth are available, as is the case for unmanned aerial vehicles (UAVs) or drones. As the extinction is, in general, frequency-dependent, a third observation may improve the inversion results. Simulations of different scenarios show that the frequency profile can be inverted to obtain information about the three-dimensional scattering structure. The acquired data also enable retrieval of the phase center depth as a function of frequency. This method allows for frequent and accurate monitoring of semitransparent targets, e.g., forests and vegetation, using a swarm of two or three drones.

Statistical analysis on branching characteristics of positive streamer discharges in N2–O2 mixtures

Streamers are fast-propagating ionization channels that can usually branch and form complex tree-like structures in dielectric media. In this paper, we perform experiments on positive streamers in different N2–O2 mixtures under varying conditions including voltage, pressure, and electrode geometry, with at least 125 discharge images captured for each condition. We present a statistical analysis on streamer branching characteristics from 3D models that are reconstructed by stereoscopic stroboscopic images and our dedicated semi-automatic 3D reconstruction method.We found that by varying the concentration of O2, the morphology and branching characteristics are greatly changed. Specifically, the average branching angle decrease significantly from 90∘ in air to 66∘ in 1% O2, suggesting that photoionization plays an important role in streamer branching. The branching angles in our work are generally larger than previously reported results due to the resolved 3D structures of discharges by our method. A linear relation between the streamer diameter ratio and the branching direction difference of two daughter branches is found, which intersects the vertical axis almost at unity. It is also found that the average branching angles, streamer velocities and diameters increase as the voltage increases. This is again attributed to stronger photoionization effect under higher voltages. The velocities and diameters are similar at different pressures but at the same reduced electric field. The average branching angle decreases from 90∘ at 133 mbar to 79∘ at 200 mbar. This suggests that stochastic fluctuations become dominant over photoionization effect at higher pressures.

Packing Soft Polygons in a Minimum Height Rectangular Target Domain

The paper studies packing polygons of variable shapes, regarding the stretching coefficient, in a rectangular target domain of minimum height. Packing objects of a variable shape have a wide spectrum of applications, e.g, in biology, materials science, mechanics, land allocation, and logistics. Interest in these problems is also due to the modeling of the structures of porous media under pressure, e.g., for creating test models of artificial digital cores. Elements of porous media can be deformed under the influence of an external force, but the mass of each particle remains unchanged. This corresponds to conservation of area for the two-dimensional case. Polygonal objects must be completely contained within the target domain (containment constraint) and do not overlap (non-overlapping constraint), provided they have free translations, continuous rotations, stretch transformations, and conserve their area. The phi-function technique is used for an analytical description of the placement constraints for variable shape polygons. Quasi-phi-functions for describing non-overlapping constraints and phi-functions for describing containment constraints are defined. The packing problem is presented in the form of a nonlinear programming model. A solution strategy is proposed, which consists of the following stages: generation of feasible starting points; search for local minima of the problem of packing soft polygons for each starting point using the decomposition algorithm; choosing the best local minimum found at the previous stage. To search for smart starting arrangements, an optimization algorithm for packing original polygons using their homothetic transformations is applied. Decomposition of the problem of packing polygons of variable shapes is based on an iterative procedure that allows reducing a large-scale problem to a sequence of smaller nonlinear programming problems (linear to the number of objects). Numerical examples are provided for oriented rectangles and non-oriented regular polygons. Keywords: packing, polygons, stretch transformation, rectangular container, quasi-phi-functions, optimization, decomposition algorithm.

A tale of two Southeast Asian states: media governance and authoritarian regimes in Singapore and Vietnam

Political scientists have crafted intricate taxonomies to classify nations beyond liberal democracy, positioning these societies along an authoritarian continuum. Despite the pivotal role of journalists in accelerating political dynamics, there exists a lack of comparative research on media governance in these regimes. Consequently, this study scrutinizes the media governance ecosystems in Vietnam and Singapore. Vietnam is a one-party authoritarian state, whereas Singapore represents a hybrid political system. However, both countries exhibit a stable and uninterrupted rule by the respective ruling party. Our research uncovers the nuances of Singapore’s media regulation, which embeds trusted stakeholders with financial interests in key press roles to reinforce the implicit political norms. Conversely, Vietnam employs a more direct, coercive, and state-centric approach. Media actors in both nations occasionally test the boundaries of acceptable discourses, with each government’s responses being shaped by specific contexts and broader history. Reforms in Vietnam, embracing privatization and commercialization, mirror Singapore’s integration of capitalism, public ownership, and commercial interests when governing media. These findings highlight diverse yet effective authoritarian media governance strategies, unique features, and commonalities in both systems. Overall, media structures in these Southeast Asian countries have undergone profound evolutions towards more sophisticated regulatory tools to manage societal and political transformations.

Peace Journalism Training for Journalists as a Contribution to PVE in the New Afghanistan

This article presents and discusses results from an exercise in comparative content analysis of news articles about issues of conflict produced by Afghan journalists before and after participating in an internationally sponsored training and mentorship programme in Peace Journalism. The programme was part of a Preventing Violent Extremism (PVE) project, intended to create community resources for resilience, in the information sphere, towards conflict issues contributing to recruitment by non-state armed groups such as Islamic State–Khorasan Province (IS–KP). Peace Journalism is familiar as the basis for media development aid in contexts of conflict; however, its use in an intervention aimed specifically at PVE is relatively new. The results showed that the programme was effective, it is argued, in terms of benefits transferred to and applied by participating journalists. A sample of articles after the training showed a markedly higher Peace Journalism quotient than a baseline sample of articles by the same journalists before it. This suggested that the training and mentorship had successfully stimulated and enabled journalistic agency, taking account of constraints imposed by media structures and wider political and social contexts. The latter have become steadily more onerous under the Islamic Emirate (Taliban) government, in power since August 2021, according to international monitoring organisations. Implications are considered, in light of the findings, for future media development aid to Afghanistan.

High-fidelity 3D simulation of dust-loading behavior and clogging process of coarse nonwoven filter media considering collision effect

The filter lifetime of fibrous media is important for the energy-saving application of air filters and efficient delivery of clean air. The clogging process significantly affects the dust-loading behavior of fibrous filter media. Therefore, an effective methodology for determining the deposition of dust particles inside filter structures is necessary. This study conducted numerical dust loading simulations on a three-dimensional (3D) X-ray tomographic structure of coarse nonwoven filter media. Spherical particles with a density of 1808 kg/m3 were used in the simulations instead of plate-like dust particles with a higher silica density. A high-fidelity simulation model was successfully developed by considering collision effects. Key factors were determined, including the Hamaker constant for the adhesion energy, restitution coefficient for the particle kinetic energy, and sliding motion. Remarkably, the deviation between the simulated and experimental dust holding capacity was less than 1 %. The developed simulation model enabled a quantitative evaluation of the clogging process and 3D in-situ evolution of particle deposition and pore structures. It was observed that 95.6 % of the maximum deposited dust mass within the fibrous structure was captured at the clogging point. Several computational methods yielded accurate pore size evaluations and clear 3D pore structure visualizations. The developed methodology for high-fidelity simulation and 3D analysis can be further applied to other two-phase filtration and separation fields, including aerosol filtration, coalescence filtration, membrane fouling, micro/nanoplastic capture, and oil/water separation.

Comparative Analysis of Mass Media in Nigeria and Ghana

This study conducts a comparative analysis of the mass media landscapes in Nigeria and Ghana, focusing on their historical development, regulatory frameworks, and content focus. Drawing on a diverse array of sources, including books, journal articles, and government reports, the research evaluates the trajectory of media evolution in both countries from their colonial past to the present day. The study employs a theoretical framework that combines the political economy of communication and the cultural studies perspective. The political economy of communication approach highlights the economic, political, and social factors that shape media content and structure, while the cultural studies perspective emphasizes the role of media in shaping cultural values and identities. The findings reveal that both countries have shared priorities in promoting national unity, addressing social and economic development issues, and preserving cultural values. The study concludes that while both countries share some commonalities, such as the emergence of indigenous broadcasters and the growth of online news, there are also notable differences. The study recommends that both Nigeria and Ghana should work to foster international collaboration in the mass media industry.

Comparing Media Systems Through the Lens of Neoliberal Hegemony: Evidence From the US and Flanders

This article argues that increased insight into the global characteristics of the post-Cold War era provides journalism scholars with alternative interpretative lenses to engage in comparative analysis of media system development in the West. We adopt the sociohistorical approach pursued by Hallin and Mancini (2004) in their seminal work <em>Comparing Media Systems</em> to embark on an examination of the dialectic relationship between global neoliberal hegemony, the transformation of media markets, and the emergence of a new journalistic consciousness (doxa). This examination concerns a comparative analysis of developments in a selection of Flemish and American legacy newspapers between 1980 and today, based on a data set consisting of 36 in-depth semi-structured interviews with high agency individuals (executive editors, managing editors, senior journalists, and publishers). The goal of the article is to establish the lens of global neoliberal hegemony as a viable alternative framework to the regional lens of the media systems typology for engaging in comparative analysis of developments in media structures and journalistic practice.

Compactons in Higher-Order Nesterenko's-Type Equations

Abstract A model describing propagation of waves in a prestressed granular media is considered. The model, having the form of evolutionary partial differential equation (PDE), is obtained from the system of ordinary differential equations (ODEs) describing dynamics of a chain of prestressed granules by means of formal asymptotic expansion. It is shown in our previous papers that in the lowest asymptotic approximation, in which both nonlinear effects and the presence of media structure are taken into account, the model equation possesses traveling wave (TW) solutions with compact support (compactons) manifesting soliton properties. In this paper, we study a higher-order evolutionary PDE obtained by taking into account previously discarded terms of the asymptotic expansion, as well as another PDE (called analogue), differing from the original one in the values of parameters and having compacton solutions expressed in analytical form. Numerical and analytical studies of both the higher-order model and its analogue allow to conclude that both models have compacton solutions exhibiting some properties of “true” solitons. This, in turn, testifies the stability of the previously used model with respect to the inclusion of the discarded terms of the asymptotic expansion.

Numerical simulation of diesel particulate filter flow characteristics optimization: From the perspective of pore structure parameters and inlet velocity

The diesel particulate filter (DPF) with porous media structure has become an essential component for diesel engines to satisfy increasingly strict emission standards. This study constructed a porous media structure model of DPF, and optimized its boundary to conduct a simulation on the flow characteristic with different influencing parameters using the lattice Boltzmann method (LBM). Results showed that the increase of the average flow velocity of the DPF model reduced the pressure drop, indicating that the flow probability of model improved. In addition, the porosity application range was expanded. The visualization and quantization of the velocity and pressure distribution with the DPF revealed that an increase of the wall thickness resulted in a higher pressure drop of the DPF, but a lower flow velocity. Further, the fractal dimension of the porous media exhibited no direct relationship with the DPF pressure and velocity performance; however, the outlet velocity and pressure drop of the model were optimized within the different porosity. Moreover, both the increase in the spectral dimension and model optimization improved the DPF permeability. The impact of increasing the inlet velocity on the pressure drop was particularly significant as it accelerated the rate of pressure drop, illustrating that a smoother porous media boundary was conducive to improve the flow performance of DPF, which facilitated a better scheme for the design of DPF porous media.

Magnetic printing characteristics of burst signals by using double magnet master media

In this study, the magnetic printing characteristics of burst signals with double magnet master (DMM) media, which consists of hard and soft magnet patterns corresponding to the burst signals, onto energy-assisted magnetic recording (EAMR) media was investigated by the micromagnetic simulation. For comparison, the magnetic printing characteristics with the conventional master media, which includes only soft magnet patterns, was also calculated. The magnetic film patterns of each master media transfer automatic-gain-control (AGC) and burst parts to the recording medium. The burst signals was amplitude AB-burst patterns, which consists of the repeated pattern region and blank area without burst patterns. Two possible master media structures of DMM media were considered, which are herein called positive- and negative- DMM media. By utilizing the positive-DMM, which spatially divides soft magnets, the AGC and the burst signals can be clearly printed, comparing with the conventional master media. While the negative-DMM is insufficient to print burst signals because the blank area without burst patterns has some non-recorded clusters. Thus, the positive-DMM are feasible for the magnetic printing of burst signals. The clear printing onto EAMR media is expected to be obtained by the optimum non-magnetic separator thickness and the optimum printing field. Therefore, the magnetic printing with positive DMM master is promising onto EAMR media.