Search results

The purpose of the paper is to analyse the performances of closures and compressibility corrections classically used in turbulence models when applied to highly-compressible turbulent boundary layers (TBLs) over flat plates.

A direct numerical simulation (DNS) database of TBLs, covering a wide range of thermodynamic conditions, is presented and exploited to perform a priori analyses of classical and recent closures for turbulent models. The results are systematically compared to the “exact” terms computed from DNS.

The few compressibility corrections available in the literature are not found to capture DNS data much better than the uncorrected original models, especially at the highest Mach numbers. Turbulent mass and heat fluxes are shown not to follow the classical gradient diffusion model, which was shown instead to provide acceptable results for modelling the vibrational turbulent heat flux.

The main originality of the present paper resides in the DNS database on which the a priori tests are conducted. The database contains some high-enthalpy simulations at large Mach numbers, allowing to test the performances of the turbulence models in the presence of both chemical dissociation and vibrational relaxation processes.

New Space activities offer benefits for human progress and life beyond the Earth. However, there is a risk that the New Space Economy may develop according to an anthropocentric mindset favouring human progress and survival at the expense of all other species and the environment. This mindset raises concerns over the social and environmental impacts of space activities and the accountability of space actors. This research article explores the accountability of space actors by presenting a pluralistic accountability framework to understand, inspire and change accountability in the New Space Economy. This study also identifies future research opportunities.

This paper is a reflective and normative essay. The arguments are developed using contemporary multidisciplinary academic literature, publicly available evidence and examples. Further, the authors use Dillard and Vinnari's accountability framework to examine a pluralistic accountability system for space businesses.

The New Space Economy requires public and private entities to embrace hybrid and pluralistic accountability for their social and environmental impacts. A new way of seeing the relationship between human life, the Earth and celestial space is needed. Accounting language is used to mirror and mobilise broader forms of responsibility in those involved in space.

This paper responds to the AAAJ's special issue call for examining how accountability can be ensured in the New Space Age. The space activities businesses conduct, and the anthropocentric view inspiring their race toward space is concerning. Hence, the authors advocate the need for rethinking accountability between humans and nature. The paper contributes to fostering the debate on social and environmental accounting and the accountability of space actors in the New Space Economy. To this end, the authors use a pluralistic accountability framework to help understand how the New Space Economy can face the risks emanating from its anthropocentric mindset.

Modern human society has continuous advancements that have a negative impact on the quality of the air. Daily transportation, industrial and residential operations churn up dangerous contaminants in our surroundings. Addressing air pollution issues is critical for human health and ecosystems, particularly in developing countries such as Egypt. Excessive levels of pollutants have been linked to a variety of circulatory, respiratory and nervous illnesses. To this end, the purpose of this research paper is to forecast air pollution concentrations in Egypt based on time series analysis.

Deep learning models are leveraged to analyze air quality time series in the 6th of October City, Egypt. In this regard, convolutional neural network (CNN), long short-term memory network and multilayer perceptron neural network models are used to forecast the overall concentrations of sulfur dioxide (SO₂) and particulate matter 10 µm in diameter (PM₁₀). The models are trained and validated by using monthly data available from the Egyptian Environmental Affairs Agency between December 2014 and July 2020. The performance measures such as determination coefficient, root mean square error and mean absolute error are used to evaluate the outcomes of models.

The CNN model exhibits the best performance in terms of forecasting pollutant concentrations 3, 6, 9 and 12 months ahead. Finally, using data from December 2014 to July 2021, the CNN model is used to anticipate the pollutant concentrations 12 months ahead. In July 2022, the overall concentrations of SO₂ and PM₁₀ are expected to reach 10 and 127 µg/m³, respectively. The developed model could aid decision-makers, practitioners and local authorities in planning and implementing various interventions to mitigate their negative influences on the population and environment.

This research introduces the development of an efficient time-series model that can project the future concentrations of particulate and gaseous air pollutants in Egypt. This research study offers the first time application of deep learning models to forecast the air quality in Egypt. This research study examines the performance of machine learning approaches and deep learning techniques to forecast sulfur dioxide and particular matter concentrations using standard performance metrics.

The purpose of this paper is to present the influence of inter-turn short circuit faults (ITSF) on electromagnetic vibration in high-voltage line-starting permanent magnet synchronous motor (HVLSPMSMS).

In this paper, the ampere–conductor wave model of HVLSPMSM after ITSF is established. Second, a mathematical model of the magnetic field after ITSF is established, and the influence law of the ITSF on the air-gap magnetic field is analyzed. Further, the mathematical expression of the electromagnetic force density is established based on the Maxwell tensor method. The impact of HVLSPMSM torque ripple frequency, radial electromagnetic force spatial–temporal distribution and rotor unbalanced magnetic tension force by ITSF is revealed. Finally, the electromagnetic–mechanical coupling model of HVLSPMSM is established, and the vibration spectra of the motor with different degrees of ITSF are solved by numerical calculation.

In this study, it is found that the 2np order flux density harmonics and (2 N + 1) p order electromagnetic forces are not generated when ITSF occurs in HVLSPMSM.

By analyzing the multi-harmonics of HVLSPMSM after ITSF, this paper provides a reliable method for troubleshooting from the perspective of vibration and torque fluctuation and rotor unbalanced electromagnetic force.

The purpose of this paper is to explore the problem of land degradation as a category of environmental terrorism, which has been increasing along with the rise of open pit mining and oil palm plantation activities.

This study uses a doctrinal approach that aims to find the best solution to address the problem of land degradation and environmental terrorism activities in Indonesia through a comparative legal study conducted with the handling of similar cases in Malaysia, which has almost the same character as Indonesia.

This paper finds that both Indonesia and Malaysia have enacted laws and regulations to address environmental concerns. However, it turns out that relying only on law enforcement is not an optimal solution. Addressing the problem of land degradation would also require the implementation of sustainable development practices, public awareness and cooperative dialogue.

This paper provides a new approach to answer the inclusion of environmental degradation as environmental terrorism, which should also be considered a crime against humanity.

This paper aims to present the case for critical realism (CR) as a framework in steering the anticipatory and participatory activities an appropriate analysis of complex problems, aiming toward a transformative change.

Through observation, interview and facilitation for Circular Design Lab and Thai Clean Air Network, this paper unpacks their foresight activities, their key findings and subsequently connects to the Morphogenesis analysis based on an alternative foresight epistemology of CR.

Foresight based on CR philosophy provides a deeper understanding of the complexity and invisibility of air pollution issues in Thailand. Acknowledging the transitive reality beyond this study’s perception, the activity design applies the iceberg models to investigate problem framing and illustrate the stratified reality in three domains: the empirical based on emission reports and legislative regulations; the actual based on patterns of farmers practice and industrial development, activated by causal mechanisms; the real based on structural and mental models, driven by cultural and belief systems in Thailand. At the bottom layer of the iceberg, the real lies the generative mechanisms of pre-existing structural and cultures that constrain Thai citizen from acting on social change.

CR’s emancipatory theory provides an immanent critique towards social improvement by illustrating comprehensive causal explanations of complex problems such as air pollution; while morphogenesis theory elaborates on the unconscious domination of the existing social structures, agencies, and cultures. Thus, the ethical inquiry of CR research is committed to the emancipation of false beliefs and creating conditions for “human prosperity”. However, this non-neutral value commitment is debated in the futures studies field.

The anticipatory activities on air pollution in Thailand bring to light the reality of power and oppression beyond human perception and illustrate the connection to the belief systems and its consequential action or lack thereof in dealing with the issues. The insight to power relationship provides an unconventional way to empower citizens in creating transformative change.

Modern foresight practice has developed under western cultures and societies. Recent efforts are made to investigate the epistemology underlying this field, for the future issues are ever more complex and interrelated across multiple sectors. This requires this study’s consideration of the meaning of knowledge and knowing, influencing the research paradigm. This paper proposes CR as a suitable foresight approach to emancipate this study from the widely accepted epistemologies and examine this study’s presupposition about social reality by a philosophical explanation based on the elements of ontology, causation, structure and persons.

The extant literature underlines the inadequacies of legal and policy frameworks addressing the safety and health concerns of sandstone mineworkers in India. Notably, Rajasthan, a state renowned for its extractive industries, mirrors these concerns. Against this backdrop, this paper aims to critically evaluate the relevant legal and policy landscape, with an emphasis on the recent central statute: the Occupational Safety, Health and Working Conditions Code of 2020 (OSHWCC). Given that the Code subsumes the key legislation pertaining to the safety and health of mineworkers, an in-depth critical analysis is essential to forge suitable policy interventions to address continued gross violations of human rights.

The critical analysis of legal and policy frameworks on silicosis in sandstone mineworkers is based on a comprehensive reading of existing literature. The literature includes relevant laws, case law, reports of the Rajasthan State Human Rights Commission and National Human Rights Commission, publicly available data and key scholarly contributions in the field.

Although the OSHWCC has made some changes to the existing regulatory architecture of mines in India, it has failed to safeguard the safety and health of mineworkers. Notably, the vast majority of mines in India – constituting approximately 90%, which are informal, seasonal and small-scale – remain beyond the jurisdiction of this Code. In Rajasthan, there are specific policies on silicosis, but these policies are poorly implemented. There is a serious shortage of doctors to diagnose silicosis cases, leading to under-diagnosis. The compensation for silicosis victims is insufficient; the distribution mechanism is complex and often delayed.

The central and many state governments have not established the regulatory institutions envisaged under the OSHWCC 2020; therefore, the working of the regulatory institutions could not be critically examined.

The paper critically evaluates laws and policies pertaining to silicosis in sandstone mineworkers, with a special emphasis on the state of Rajasthan. It offers a comprehensive critique of the OSHWCC of 2020, which has not received much attention from previous studies.

This paper aims to analyze regulation regarding sustainable construction procurement in Southeast Asia and provide a reconstruction of regulation regarding the sustainable construction procurement to prevent land degradation.

This was done through legal research methods, mainly historical and systematical interpretation. The approaches used in this paper are the conceptual approach, statute approach and comparative approach.

By analyzing the related legal norms, it can be understood that many nations in Southeast Asia do not have regulation regarding sustainable construction procurement. Between Indonesia, Singapore and Thailand, only Indonesia has a ministrial regulation that provides general norms regarding sustainable construction procurement. Regarding the reconstruction of regulation, the bare minimum standards consist of principle, indicators, pillar, the phases of the procurement, law enforcement, both preventive and repressive, and sustainable procurement committee.

This research is limited to regulation in Southeast Asian region. By analyzing the regulation, this paper will provide a reconstruction of regulations regarding sustainable construction procurement that will act as an ground rules. Having the same ground rules will create synergies between countries in Southeast Asia to apply the principles of sustainable procurement and move together toward to prevent land degradation.

To the best of the authors’ knowledge, this paper is the first systematic legal research that compares regulations from three nations in Southeast Asia regarding sustainable construction procurement and also the first paper to provide reconstruction of regulation regarding sustainable construction procurement to prevent land degradation.

Material extrusion-based additive manufacturing is a prominent manufacturing technique to fabricate complex geometrical three-dimensional (3D) parts. Despite the indisputable advantages of material extrusion-based technique, the poor surface and subsurface integrity hinder the industrial application of this technology. The purpose of this study is introducing the hot air jet treatment (HAJ) technique for surface treatment of additive manufactured parts.

In the presented research, novel theoretical formulation and finite element models are developed to study and model the polishing mechanism of printed parts surface through the HAJ technique. The model correlates reflow material volume, layer width and layer height. The reflow material volume is a function of treatment temperature, treatment velocity and HAJ velocity. The values of reflow material volume are obtained through the finite element modeling model due to the complexity of the interactions between thermal and mechanical phenomena. The theoretical model presumptions are validated through experiments, and the results show that the treatment parameters have a significant impact on the surface characteristics, hardness and dimensional variations of the treated surface.

The results demonstrate that the average value of error between the calculated theoretical results and experimental results is 14.3%. Meanwhile, the 3D plots of Ra and Rq revealed that the maximum values of Ra and Rq reduction percentages at 255°C, 270°C, 285°C and 300°C treatment temperatures are (35.9%, 33.9%), (77.6%,76.4%), (94%, 93.8%) and (85.1%, 84%), respectively. The scanning electron microscope results illustrate three different treatment zones and the treatment-induced and manufacturing-induced entrapped air relief phenomenon. The measured results of hardness variation percentages and dimensional deviation percentages at different regimes are (8.33%, 0.19%), (10.55%, 0.31%) and (−0.27%, 0.34%), respectively.

While some studies have investigated the effect of the HAJ process on the structural integrity of manufactured items, there is a dearth of research on the underlying treatment mechanism, the integrity of the treated surface and the subsurface characteristics of the treated surface.

Coal is the basic energy and essential resource in China, which is crucial to the economic lifeline and energy security of the country. Coal mining has been ever exposed to potential safety risks owing to the complex geologic environment. Effective safety supervision is a vital guarantee for safe production in coal mines. This paper aims to explore the impacts of the internet+ coal mine safety supervision (CMSS) mode that is being emerged in China.

In this study, the key factors influencing CMSS are identified by social network analysis. They are used to develop a multiple linear regression model of law enforcement frequency for conventional CMSS mode, which is then modified by an analytical hierarchy process to predict the law enforcement frequency of internet+ CMSS mode.

The regression model demonstrated high accuracy and reliability in predicting law enforcement frequency. Comparative analysis revealed that the law enforcement frequency in the internet+ mode was approximately 40% lower than the conventional mode. This reduction suggests a potential improvement in cost-efficiency, and the difference is expected to become even more significant with an increase in law enforcement frequency.

To the best of the authors’ knowledge, this is one of the few available pieces of research which explore the cost-efficiency of CMSS by forecasting law enforcement frequency. The study results provide a theoretical basis for promoting the internet+ CMSS mode to realize the healthy and sustainable development of the coal mining industry.