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The classical advection-dispersion equation (ADE) model cannot accurately depict the gas transport process in natural geological formations. This paper aims to study the behavior of CO₂ transport in fractal porous media by using an effective Hausdorff fractal derivative advection-dispersion equation (HFDADE) model.

Anomalous dispersion behaviors of CO₂ transport are effectively characterized by the investigation of time and space Hausdorff derivatives on non-Euclidean fractal metrics. The numerical simulation has been performed with different Hausdorff fractal dimensions to reveal characteristics of the developed fractal ADE in fractal porous media. Numerical experiments focus on the influence of the time and space fractal dimensions on flow velocity and dispersion coefficient.

The physical mechanisms of parameters in the Hausdorff fractal derivative model are analyzed clearly. Numerical results demonstrate that the proposed model can well fit the history of gas production data and it can be a powerful technique for depicting the early arrival and long-tailed phenomenon by incorporating a fractal dimension.

To the best of the authors’ knowledge, first time these results are presented.

Autonomous floor-cleaning robots (AFCRs) have become increasingly popular due to their ability to provide efficient and effective cleaning without the need for human intervention. These robots can perform various cleaning tasks, such as vacuum cleaning, mopping, scrubbing or sweeping, in domestic or industrial setups. As the use of floor-cleaning robots continues to grow, this paper aims to document key technological advancements.

The structure of the present work relies on published research articles excavated from general online research databases such as Google Scholar, Web of Science and Scopus. The authors use a variety of keywords and titles to search for research papers. Finally, 93 research articles are selected for review based on abstracts and key results that match AFCRs.

According to market trends, floor-cleaning robots dominate other cleaning areas. This review mainly focuses on five attributes of floor-cleaning robots: design and development of AFCR, complete coverage path planning, the application of machine learning (ML)/deep learning (DL), optimisation strategies for qualitative output and ethnographic studies. It also consists of discussions based on the results of reported technical works. Hence, AFCRs have dominated the market in the past decade and are likely to be more aggressive in the coming years.

To the best of the authors’ knowledge, only a survey article based on US-granted patents published in 2013 constitutes a review work in the research domain on AFCRs. In 2021, another review conducted a survey on the latest technological advancements in window-cleaning robots. It reviewed in detail the locomotion aspects, control mechanisms, adhesion mechanisms, sensors and actuators required for window-cleaning robots. In 2019, a comprehensive review was published on cleaning robots from a control strategy perspective for domestic applications. Therefore, the authors have crafted this review to understand the evolution of floor-cleaning robots in the past decade.

This study investigates the relationship between bank capital and liquidity creation and further examines the effect that institutional quality has on this relationship in Sub-Saharan Africa (SSA).

The data comprise 41 universal banks in nine SSA countries from 2010 to 2022. The study employs the two-step system generalized methods of moments and further uses alternative estimators such as the fixed-effect and two-stage least squares methods.

The empirical results show that bank capital has a direct positive and significant effect on liquidity creation. In addition, the positive effect of bank capital on liquidity creation is enhanced, particularly in a strong institutional environment. The results imply that nonconstraining capital regulatory policies bolster bank solvency, improve risk-absorption capacity and increase liquidity creation.

This study has several policy implications. First, it provides empirical evidence on the position of banks in SSA on the financial fragility and risk-absorption hypothesis of bank capital and liquidity creation debates. This study shows that the effect of bank capital on liquidity creation in SSA countries is positive and supports the risk-absorption hypothesis. Second, this study highlights that a country's quality institutions can complement bank capital to increase liquidity creation. In addition, this study highlights that nonconstraining capital regulatory policies will bolster bank solvency, improve risk-absorption capacity and increase liquidity creation.

The novelty of this study is that it introduces the country's quality institutional environment into bank capital and liquidity creation links for the first time in SSA.

This paper aims to identify the mechanism through which consumer empowerment, created via the Facebook brand page (FBBP), is transformed into brand page stickiness. Specifically, a model examining the mediating role of FBBP experience and the moderating role of brand love is proposed and tested.

Data from 283 FBBP users were analyzed using structural equation modeling with partial least squares.

The findings reveal the positive effect of consumer empowerment and brand page experience on brand page stickiness. The mediating role of brand page experience and the moderating role of brand love were prominent in the consumer empowerment–brand page stickiness link.

This paper is novel in inaugurating the association between consumer empowerment and FBBP stickiness, which is mediated by brand experience and moderated with brand love. This paper enriches the understanding of how brand page stickiness can be enhanced in the social media context.

This paper guides managers to best utilize FBBP to create a pleasant experience and yield stickiness.

We aim to provide a systematic literature review of the determinants and consequences of labor investment efficiency in an international context. First, we offer a theoretical discussion of labor investment efficiency, followed by an examination of its measurement. Next, we review the determinants of labor investment efficiency, categorizing them into firm fundamentals including financial reporting quality, governance and controls, corporate social responsibility/environmental regulation and macroeconomic determinants. Finally, we review the limited empirical literature on the consequences of labor investment efficiency. We also provide some suggestions for future research.

We perform a systematic literature review using the Preferred Reporting Items for a Systematic Review of Meta-Analysis (PRISMA) guidelines to examine archival studies investigating the determinants and consequences of labor investment efficiency. Using a Boolean search strategy on the Scopus and PRISMA selection criteria, we review 86 published archival research articles from 2014 to the end of August 2024.

Our review highlights that firm-level fundamental factors including financial reporting quality have profound implications for labor investment efficiency. Effective governance mechanisms also help mitigate agency conflicts and information asymmetries and alleviate labor investment inefficiencies. Furthermore, the influence of regulations including ESG-related regulations and macroeconomic factors play a crucial role in shaping labor investment decisions. We find very little research on the consequence of labor investment efficiency.

Our review has highlighted that well-functioning corporate governance tools are effective in mitigating inefficient labor investments. Stakeholders, therefore, should ensure that firms have effective internal governance mechanisms in place and that external governance regulations complement and where necessary act as substitutes for internal governance mechanisms to optimize labor investments.

To the best of our knowledge, this study represents the first systematic review of extant research on labor investment efficiency. Our review highlights some research gaps, particularly about the consequences of labor investment efficiency and offers some suggestions for future research.

This paper aims to discuss the electromagnetic scattering characteristics of the afterbody model with two drag plates.

The plane shape of the drag plate model is designed as a rectangle. High-precision unstructured grid technology is used to treat the target surface. A calculation method based on multiple tracking and dynamic scattering module is presented to calculate the radar cross section (RCS).

The results show that under the given observation conditions, the RCS and surface scattering characteristics of a single drag plate change with the increase of the opening angle, which makes the forward RCS of the afterbody model change more than 8.43 dBm2. The opening of two resistance plates at different fixed angles has little effect on the peak value and position of the RCS of the afterbody model. The dynamic deflection of the two drag plates can bring 16.78 dBm2 fluctuations to the forward RCS of the afterbody model, and more than 25.59 dBm2 fluctuations to the side RCS.

The installation positions of the drag plate on the aircraft are various, so the method in this paper can provide reference and support for RCS analysis of the speed brake at other positions.

The presented calculation method is of engineering value to analyze the electromagnetic scattering characteristics of the drag plate.

Considering that listed companies are the main body of natural resource consumption and pollutant emission, this study aims to explore the stock price effect and source channels of green bond issuance of listed companies. This is extremely necessary to promote listed companies to actively fulfill their environmental responsibilities so as to achieve sustainable economic and social development.

In this paper, the companies that issued green bonds in Shanghai and Shenzhen stock markets in China from 2016 to 2018 are used as samples. First of all, the authors adopt the event study method and match the two models to prove that there is a stock price effect in green bond issuance. Then, the authors introduce the general regression model to analyze the sources of the stock price effect of green bond issuance in detail through three channels: “financing cost,” “investor attention” and “fundamental.”

In the above three channels, the “investor attention” channel can well explain the stock price effect of green bond issuance. Meanwhile, the authors also find that the stock price effect of the subsequent issuance of green bonds is more significant than that of the first time, non-financial companies are more pronounced than financial companies, public issuance are more obvious than private issuance, state-owned companies are more notable than non-state-owned companies, small-scale companies are more evident than large-scale companies and companies with high equity concentration are clearer than those with low equity concentration.

Taking China as the research object for the first time, this paper comprehensively employs the capital asset pricing model and Fama–French five-factor model to discuss the stock price effect of green bond issuance of listed companies. Secondly, this paper also studies whether the way of green bond issuance, the type and size of the company, as well as the degree of ownership concentration will have different effects on the stock prices of listed companies. The research results provide new ideas and methods for the stock price effect of green bond issuance.

This study aims to explore the dissemination and evolutionary path of online public opinion from a crisis management perspective. By clarifying the influencing factors and dynamic mechanisms of online public opinion dissemination, this study provides insights into attenuating the negative impact of online public opinion and creating a favorable ecological space for online public opinion.

This research employs bibliometric analysis and CiteSpace software to analyze 302 Chinese articles published from 2006 to 2023 in the China National Knowledge Infrastructure (CNKI) database and 276 English articles published from 1994 to 2023 in the Web of Science core set database. Through literature keyword clustering, co-citation analysis and burst terms analysis, this paper summarizes the core scientific research institutions, scholars, hot topics and evolutionary paths of online public opinion crisis management research from both Chinese and international academic communities.

The results show that the study of online public opinion crisis management in China and internationally is centered on the life cycle theory, which integrates knowledge from information, computer and system sciences. Although there are differences in political interaction and stage evolution, the overall evolutionary path is similar, and it develops dynamically in the “benign conflict” between the expansion of the research perspective and the gradual refinement of research granularity.

This study summarizes the research results of online public opinion crisis management from China and the international academic community and identifies current research hotspots and theoretical evolution paths. Future research can focus on deepening the basic theories of public opinion crisis management under the influence of frontier technologies, exploring the subjectivity and emotionality of web users using fine algorithms and promoting the international development of network public opinion crisis management theory through transnational comparison and international cooperation.

Today, millions of exporters and importers are using hundreds of business-to-business (B2B) electronic marketplaces to buy or sell goods and services. With this reason, this study aims to provide the related literature sufficient information concerning the most appropriate and beneficiary criteria which should be taken into consideration in the web pages of B2B companies via applying a content analysis method. The analysis results exhibit that globally oriented websites like B2B marketplaces must contain at least two or three language options, since people from different parts of the world speak and learn different languages according to their geography; and that B2B websites which do not provide trade assurances must consider adding this feature to attract more customers. In the scope of the study, it has been found out that all the selected websites take a good care of the information they share. When visiting these companies, it is really easy to learn everything about industries and international trade relations. Some of them even share information about the effect of the COVID-19 outbreak on industries. Among all the websites analyzed in the scope of the study, only Alibaba.com meets all the criteria taken into consideration. Moreover, it would be appropriate to suggest that Turkish B2B e-marketplaces, such as Tradeatlas.com, ptttrade.com, and steelorbis.com, should have these criteria to become leading B2B e-marketplaces in the world. Finally, it can be suggested that websites should prepare specific pages for newcomers to enlighten them in the best way they can do.