Coalbed Methane (CBM) has become an important gas resource in recent decades. The brittle property of coal matrix and overactive operation make the migration of coal fines inevitable. Blockage by coal fines that plugs flow paths is a non-negligible issue that results in a significant decline in gas production. By setting different experimental conditions with the following factors—coal fines concentration of the mixture displacing fluids, constant flow pump rate, inlet pressure, outlet pressure and confining pressure—six experimental schemes were designed to investigate the two-phase water and coal fines flow in natural core samples. When the differential pressure and flooding flow reach a pseudo-steady status, the equivalent permeability of coal samples can be approximately calculated considering coal fines migration. Furthermore, the influences of coal fines migration on the cleat opening and permeability variation are analyzed in the porous coal medium. The study will benefit CBM development and save pump maintenance costs. In this work, we found that maintaining the differential pressure for a longer period may result in new cleat openings and severe coal rock damage during the single-phase water flooding process. While coal fines may plug some natural cleats and pores, especially in the core samples with micro-cleats during the two-phase flooding stage, coal fines migration significantly reduces the equivalent permeability and dewatering ability of the coal rock in the earlier flooding. While enlarging the differential pressure in two-phase water and fines flooding, breakthrough of coal fines from the samples contributes to widened cleats. While coal fines are difficult to flood into the core pores for low-permeability core samples, coal fines gather in the inlet, and it is also difficult to reach the pseudo-steady status even under higher differential pressure. The damage to permeability mainly occurs in the early stage of coal fines migration, and an abrupt increase in the flow velocity can damage reservoirs and induce substantial coal fines generation. Thus, maintaining a stable effective strength and a controlled depressurization rate during drainage can effectively constrain coal fines output and decrease permeability damage within coal reservoirs. Full article

This paper applies wavelet multi-resolution analysis (MRA), combined with two types of causality tests, to investigate causal relationships between three variables: real oil price, real interest rate, and unemployment in Norway. Impulse response functions were also utilised to examine effects of innovation in one variable on the other variables. We found that causal relations between the variables tend to be stronger as the wavelet time scale increases; specifically, there were no causal relationships between the variables at the lowest time scales of one to three months. A causal relationship between unemployment rate and interest rate was observed during the period of two quarters to two years, during which time a feedback mechanism was also detected between unemployment and interest rate. Causal relationships between oil price and both interest rate and unemployment were observed at the longest time scale of eight quarters. In conjunction with Granger causality analysis, impulse response functions showed that unemployment rates in Norway respond negatively to oil price shocks around two years after the shocks occur. As an oil exporting country, increases (or decreases) in oil prices reduce (or increase) unemployment in Norway under a time horizon of about two years; previous studies focused on oil importing economies have generally found the inverse to be true. Unlike most studies in this field, we decomposed the implicit aggregation for all time scales by applying MRA with a focus on the Norwegian economy. Thus, one main contribution of this paper is that we unveil and systematically distinguish the nature of the time-scale dependent relationship between real oil price, real interest rate, and unemployment using wavelet decomposition. Full article

Today, there are many discussions and guidelines on the issue of smart cities (meaning cities that introduced smart technology) from the perspective of traditional urban policy. Smart city policies focusing on technology have been criticized for eliminating the different levels of factors that surround smart cities. When governments fail to consider different factors in implementing smart policies, they might not effectively provide quality services to citizens, because smart cities involve not only technical elements, but also the complex elements surrounding them (e.g., the policy ecosystem and urban infrastructure). This exploratory study examines the determinants of smart cities and their priorities through an analytic hierarchy process analysis. In this study, the priority internal factors appeared in the order of citizen involvement, leadership, and infrastructure, and the priority external factors took the order of political will, stakeholders, and the fourth Industrial Revolution. In addition, this study shows that the presence of communication channels, public hearings, and direct stakeholders is important for analyzing each sub-factor. Full article

Sustainability (SUS) is a journal in the field of environmental, cultural, economic and social sustainability of human beings and civilization, which was founded in 2009. This paper provides a comprehensive bibliometric overview of the journal and 6459 publications from 2009 to 2018. In the paper, we first introduce the materials and methods used. Next, we provide the bibliometric results in four parts. In the first part, we present the publication structure and citation structure of SUS, including annual trends of publications and citations, sources that cite SUS publications, and the most highly cited papers in SUS. The primary influential countries and institutes as well as their co-authorship networks are illustrated in the second part. The co-citation networks of cited references, journals and authors are shown in the third part. Finally, the co-occurrence network of keywords and bursting citation keywords is detected. VOSviewer and CiteSpace software packages are used for graphical visualization. Full article

The implementation of sustainable systems is an essential requirement in modern manufacturing, in order to minimize the environmental and health concerns, and conserves energy and natural resources. The sustainable manufacturing approach is identified through three main levels, namely: product, process, and system scales. The interactions among these levels provide the required sustainable target. To achieve a sustainable manufacturing system, it is very important to understand and define the concepts and needs related to the sustainability approach. In addition, defining and understanding the implementation steps as well as the assessment method to build a sustainable manufacturing system is required. In this work, a study discussing the sustainable manufacturing approach is presented in terms of concepts, implementation steps, and assessment methods. Full article

Socio-ecological consequences emanating from inadequate compliance of environmental standards by the business firms’ operations in institutionally weak developing countries must be included in the research on organizations and their relationship with the natural environment. Business firms should be held accountable for the socio-ecological degradation generated from their unsustainable business operations. To improve our understanding of the environmental degradation created by polluting manufacturing firms in developing countries, we have adopted an exploratory qualitative research approach. Results of this study indicate that polluting industries’ (e.g., tannery, pulp & paper, fertilizer, textile, and cement) unsustainable practices have enormous impact on human health and the natural environment, resulting in enormous socio-ecological problems that ultimately create huge social costs in countries such as Bangladesh. Corporate environmental responsiveness is largely nonexistent in the polluting industries in Bangladesh. Full article