Ho Chi Minh City University of Transport

Dang N.C., Moreno-García M.N., De la Prieta F.

The study of public opinion can provide us with valuable information. The analysis of sentiment on social networks, such as Twitter or Facebook, has become a powerful means of learning about the users’ opinions and has a wide range of applications. However, the efficiency and accuracy of sentiment analysis is being hindered by the challenges encountered in natural language processing (NLP). In recent years, it has been demonstrated that deep learning models are a promising solution to the challenges of NLP. This paper reviews the latest studies that have employed deep learning to solve sentiment analysis problems, such as sentiment polarity. Models using term frequency-inverse document frequency (TF-IDF) and word embedding have been applied to a series of datasets. Finally, a comparative study has been conducted on the experimental results obtained for the different models and input features.

Hoang A.T., Pham V.V., Nguyen X.P.

Among the main components of a smart city, the energy system plays a vital and core role in the transition towards a sustainable urban life. Furthermore, the utilization of renewable energy sources has been demonstrated as a significant contribution to reducing pollutant emissions and enhancing the quality of the living environment. Therefore, designing the energy systems based on clean and renewable criteria is considered a sustainable solution for smart cities. Indeed, the deep and rapid penetration of renewable energy-based technologies have been believed to very well fit into a smart city under various scales, this could supply a secure basis for a modern society with a low-carbon economy. In this review paper, the main components and roles of renewable energy resources (such as solar, wind, geothermal, hydropower, ocean, and biofuels) for the smart city were fully introduced. Besides, integrating the renewable sources form into the energy systems of smart cities was thoroughly analyzed on the basis of technical and economic criteria. Finally, existing challenges and future scenarios were also discussed in detail to clarify the progress and perspective of smart renewable energy systems for the smart city. In general, the integration of renewables into energy systems of the smart city is a sagacious perspective and solution aiming to achieve cleaner process and more sustainable development. However, the optimization issues of the energy system for integrating of renewable components, ensuring good stability, maximizing the operating range, and minimizing the investment costs should be critically evaluated in the future works. • Designing tools and key criteria for smart renewable energy systems. • Efficiency and prospect of integrating renewables into energy system for smart city. • Existing problems and challenges for renewable-based energy system in smart city. • Future scenarios for the sustainable development of energy system in smart city.

Hoang A.T., Sandro Nižetić, Olcer A.I., Ong H.C., Chen W., Chong C.T., Thomas S., Bandh S.A., Nguyen X.P.

Being declared a global emergency, the COVID-19 pandemic has taken many lives, threatened livelihoods and businesses around the world. The energy industry, in particular, has experienced tremendous pressure resulting from the pandemic. In response to such a challenge, the development of sustainable resources and renewable energy infrastructure has demonstrated its potential as a promising and effective strategy. To sufficiently address the effect of COVID-19 on renewable energy development strategies, short-term policy priorities should be identified, while mid-term and long-term action plans should be formulated in achieving the well-defined renewable energy targets and progress towards a more sustainable energy future. In this review, opportunities, challenges, and significant impacts of the COVID-19 pandemic on current and future sustainable energy strategies were analyzed in detail; while drawing from experiences in identifying reasonable behaviors, orientating appropriate actions, and policy implications on the sustainable energy trajectory were also mentioned. Indeed, the question is that whether the COVID-19 pandemic will kill us or provide us with a precious lesson on future sustainable energy development.

Le T.T., Sharma P., Bora B.J., Tran V.D., Truong T.H., Le H.C., Nguyen P.Q.

This comprehensive study assesses the current state of the hydrogen energy system and investigates its potential to transform the global energy landscape while addressing important concerns about climate change. While hydrogen energy has numerous advantages, including sustainability and cleanliness, it faces substantial challenges in the areas of storage, manufacturing, distribution, infrastructure, safety, and cost. Scholars, lawmakers, business leaders, and the general public must all work together to address these complex issues. The research emphasizes the significance of breakthrough technology and astute government policies for the successful development and widespread deployment of hydrogen energy systems. It highlights that this revolutionary effort cannot be performed in solitude. Public education and enhanced awareness appear to be significant factors in promoting greater acceptance and use of hydrogen energy. Furthermore, the study identifies critical future research objectives. It underlines the importance of enhancing the efficiency, sustainability, safety, and economic feasibility of hydrogen energy systems. The development of new storage systems, superior infrastructure designs, and seamless integration technologies is vital to achieving the full potential of hydrogen energy. Finally, the research presented here gives a critical assessment of the hydrogen energy situation and outlines a roadmap toward a more sustainable and resilient future. The review's conclusions are significant for policymakers, academics, and stakeholders because they provide critical insights into the opportunities and problems associated with realizing the full potential of hydrogen energy.

Sharma P., Said Z., Kumar A., Nižetić S., Pandey A., Hoang A.T., Huang Z., Afzal A., Li C., Le A.T., Nguyen X.P., Tran V.D.

Hoang A.T., Varbanov P.S., Nižetić S., Sirohi R., Pandey A., Luque R., Ng K.H., Pham V.V.

The proper handling of Municipal Solid Waste (MSW) is critical due to its high generation rate and the potential to minimise environmental impacts by simultaneously reducing resource depletion and pollution. MSW utilization for recycling is important for transforming the linear economy model into a circular one. The current review analyses and categorises MSW to energy technologies into direct and indirect approaches taking the Circular Economy perspective. The direct approach involves incinerating MSW for heat recovery. The indirect approach, including thermochemical and biochemical processes , is more complicated but attractive due to the variety of the valorized products – such as syngas , bio-oil, biochar, digestate, humus. However, consensus on the best MSW treatment approach is yet to be established due to the inconsistency of assessment criteria in the existing studies. In the case of converting MSW to energy (Waste-to-Energy – W2E), its economic indicators, such as capital, compliance, and operation cost, are important criteria when implementations are considered. In the current work, the critical characteristics of technologies for the MSW to energy routes are scrutinised. In addition, the economic characteristics and the role of MSW in the circular bio-economy is also thoroughly evaluated. Methods to advocate the industrial adoption and important assessing aspects of W2E are proposed at the end of the review to address the environmental and resource management issues related to MSW – most notably dealing with the uncertainty in composition and amounts, the energy efficiency and the resource demands of the W2E processing. • Direct and indirect valorisation techniques for MSW are reviewed. • The economic characteristics and energy production viability of MSW are analysed. • Suggested assessment criteria for fair comparison of Waste-to-Energy technologies. • The low economic viability of Waste-to-Energy due to ignoring environmental benefits. • Methods to advocate the industrial adoption of W2E are proposed.

Hoang A.T., Foley A.M., Nižetić S., Huang Z., Ong H.C., Ölçer A.I., Pham V.V., Nguyen X.P.

The maritime sector has been searching for efficient solutions to change energy consumptions patterns of ports and ships to ensure sustainable operation and to reduce CO 2 emissions to support sustainable transport in line with International Maritime Organization (IMO) policy guidelines. Therefore, pursuing smart strategies by utilizing renewable energy sources , clean fuels, smart grid, as well as measures of efficient-energy use are beneficial towards attaining the core goals of the IMO, specifically CO 2 emission reduction in the future. In this review work, the main methods and criteria for monitoring CO 2 emission from ports and ships are meticulously presented. Advanced renewable energy technologies connected with sources such as solar, wind, tidal, wave, and alternative fuels and their application in ports to reduce CO 2 are thoroughly examined. In addition, energy-saving techniques and strategies for alternative power and fuels in ships are comprehensively evaluated. The key finding is that port-to-ship interactions such as using zero-emission energy sources or nearly zero-emission approaches could offer significant benefits for CO 2 emission reduction. Finally, it is recommended that smart approaches associated with efficient and clean energy use for the port-to-ship pathways to generate net zero-CO 2 emissions for the maritime shipping sector need further urgent investigation. • Approaches for monitoring CO 2 emission from ports and ships. • Smart technologies and clean energy for CO 2 reduction of the port-to-ship pathway. • Integrated strategies of renewable energy as efficient solution for CO 2 reduction. • Future scenarios regarding energy-efficient use, renewable energy, smart strategy.

Hoang A.T., Nižetić S., Cheng C.K., Luque R., Thomas S., Banh T.L., Pham V.V., Nguyen X.P.

The concentrations of heavy metal ions found in waterways near industrial zones are often exceed the prescribed limits, posing a continued danger to the environment and public health. Therefore, greater attention has been devoted into finding the efficient solutions for adsorbing heavy metal ions. This review paper focuses on the synthesis of carbon nanotubes (CNTs) from biomass and their application in the removal of heavy metals from aqueous solutions. Techniques to produce CNTs, benefits of modification with various functional groups to enhance sorption uptake, effects of operating parameters, and adsorption mechanisms are reviewed. Adsorption occurs via physical adsorption, electrostatic interaction, surface complexation, and interaction between functional groups and heavy metal ions. Moreover, factors such as pH level, CNTs dosage, duration, temperature, ionic strength, and surface property of adsorbents have been identified as the common factors influencing the adsorption of heavy metals. The oxygenated functional groups initially present on the surface of the modified CNTs are responsible towards the adsorption enhancement of commonly-encountered heavy metals such as Pb 2+ , Cu 2+ , Cd 2+ , Co 2+ , Zn 2+ , Ni 2+ , Hg 2+ , and Cr 6+ . Despite the recent advances in the application of CNTs in environmental clean-up and pollution treatment have been demonstrated, major obstacles of CNTs such as high synthesis cost, the agglomeration in the post-treated solutions and the secondary pollution from chemicals in the surface modification, should be critically addressed in the future studies for successful large-scale applications of CNTs. • Pristine CNTs possess strong hydrophobicity and a low affinity towards heavy metals. • Modifications of pure CNTs are necessary to enhance the adsorption efficiency. • SWCNTs have demonstrated greater adsorption properties compared to MWCNTs. • Complicated extraction from liquid solutions and high reusability for CNTs.

Tuan Hoang A., Nižetić S., Chyuan Ong H., Tarelko W., Viet Pham V., Hieu Le T., Quang Chau M., Phuong Nguyen X.

• Mechanism, classification, and evolutions of ANN model for prediction. • Performance of ANN model for predicting engine behaviors fueled with biodiesel. • Challenges and future direction of ANN model for engine application. Biodiesel has been emerging as a potential and promising biofuel for the strategy of reducing toxic emissions and improving engine performance. Computational methods aiming to offer numerical solutions were inevitable as a study methodology which was sometimes considered the only practical method. Artificial neural networks (ANN) were data-processing systems, which were used to tackle many issues in engineering and science, especially in some fields where there was a failure of the conventional modeling approaches. Thus, it was believed that the best choice was the development of a novel approach like the ANN model to anticipate engine performance and exhaust emissions with high accuracy. In this review paper, the structure and applicability of the ANN model were comprehensively evaluated. More importantly, the use of ANN with trained, tested, and validated data was introduced to determine the performance and emission characteristics of a diesel engine fueled with biodiesel-based fuel. In general, the ANN model could supply a relatively high determination coefficient as compared between predicted results and experimental data, showing that the ANN model could have a good ability to predict the engine behaviors with an accuracy higher than 95%.

Dao N., Pham Q., Tu N.H., Thanh T.T., Bao V.N., Lakew D.S., Cho S.

Current access infrastructures are characterized by heterogeneity, low latency, high throughput, and high computational capability, enabling massive concurrent connections and various services. Unfortunately, this design does not pay significant attention to mobile services in underserved areas. In this context, the use of aerial radio access networks (ARANs) is a promising strategy to complement existing terrestrial communication systems. Involving airborne components such as unmanned aerial vehicles, drones, and satellites, ARANs can quickly establish a flexible access infrastructure on demand. ARANs are expected to support the development of seamless mobile communication systems toward a comprehensive sixth-generation (6G) global access infrastructure. This paper provides an overview of recent studies regarding ARANs in the literature. First, we investigate related work to identify areas for further exploration in terms of recent knowledge advancements and analyses. Second, we define the scope and methodology of this study. Then, we describe ARAN architecture and its fundamental features for the development of 6G networks. In particular, we analyze the system model from several perspectives, including transmission propagation, energy consumption, communication latency, and network mobility. Furthermore, we introduce technologies that enable the success of ARAN implementations in terms of energy replenishment, operational management, and data delivery. Subsequently, we discuss application scenarios envisioned for these technologies. Finally, we highlight ongoing research efforts and trends toward 6G ARANs.