Growing concern about global climate change has led to considerable interest in investigating renewable energy sources such as the biological conversion of biomass to methane in an anaerobic environment. Through a series of complicated biochemical interactions, it uses various bacterial species to degrade biodegradable material in the feedstock. Due to the complex and interacting biochemical processes, anaerobic digestion has nonlinear dynamics. Anaerobic digestion is highly at risk of instabilities and uncertainties because of its dynamic and nonlinear behavior, uncertain feedstock quality, and sensitivity to the process’s environmental conditions. Therefore, effectively operating a biogas production unit necessitates a thorough understanding of the system’s uncertainties. The present study aims to identify and assess the sources and methods of coping with the uncertainties in anaerobic digestion processes through a narrative review. Moreover, the knowledge gap is also investigated to reveal the challenges and opportunities to have a robust model. The results indicate that the unpredictability of model parameters and input variables were the most significant source of uncertainty, and the Monte Carlo technique, confident interval, and interval observers, as well as sensitivity analysis were the most frequently used tools to cope with these uncertainties.

Objective of this study is to develop a novel, effective, and robust Sliding Mode Control (SMC) method for quadcopters (also called quadrotors) based on Adaptive Neuro-Fuzzy Inference System (ANFIS) for the purposes of enhancing trajectory tracking performance and realizing safe and reliable flight. In the paper, the ANFIS was combined with SMC technology to propose a scheme of adaptive robust controller, which is composed of three sub-controllers, x position controller, y position controller, and z position (altitude) controller. The proposed method can realize position tracking control of quadcopters in the presence of external disturbances. With the help of ANFIS, an adjustable gain rather than a fixed gain was established for the SMC controller, the optimal output could be attained based on a set of rules, and the position control gain was updated by ANFIS, enabling the SMC to adapt to environmental changes. Through modelling, simulation and comparison, experimental data verified that the proposed ANFIS-SMC controller outperformed conventional SMC controller in terms of convergence speed, robustness, accuracy, and stability with a maximum mean error of 0.125 meters in trajectory tracking. Research findings of this paper could contribute to the development of robust and responsive control strategies for Unmanned aerial vehicles (UAVs) trajectory tracking by providing valuable insights into the design of more effective and efficient control systems for UAVs, particularly in the context of dynamic environmental conditions.

The concentration of pharmaceutical compounds and nutrients present in perennial streams, springs and a lake on the island of O‘ahu, Hawai‘i were measured under drought conditions between 2020 and 2022. The combined island-wide daily release of wastewater to the environment on O‘ahu from the continued use of legacy On-Site Sewage Disposal Systems (OSDS) and from exfiltration from the 3,400-kilometer network of underground sewer lines has been estimated to be about 80 million liter per day (mld), or around 3.9% of the total island-wide groundwater flux to the ocean. The 36 streams and 11 springs sampled were located down-gradient of areas with varying densities of OSDS and sewage lines while the lake sampled (Lake Wilson) receives direct input from the wastewater treatment plant that serves Central O‘ahu. Average pharmaceutical and nutrient levels in streams and springs sampled in areas with high densities of OSDS and sewer lines were slightly higher, but not statistically different than concentration levels measured in streams and springs in areas with low densities of OSDS and low sewer line densities. The average sulfamethoxazole and carbamazepine levels measured in Lake Wilson, the only water body on O‘ahu where treated wastewater is discharged into fresh water, are three to four times higher than average levels measured in the island’s streams and springs. The presence of elevated concentrations of nitrate and silica in some streams and springs on O‘ahu predominately reflects the impact of the historical use of up-gradient lands for sugarcane cultivation rather than wastewater input. The trace levels of pharmaceuticals detected in O‘ahu streams and springs under baseflow conditions suggest that the actual combined input of wastewater to the environment from legacy OSDS and exfiltration from sewer lines is less than 20% the wastewater flux previously estimated.

Purpose: Microcredits will remain crucial to rural households over a long period as they provide small loans to the needy, making it an essential aspect of rural finance. Due to the rural credit market's structure and financial inclusion problem, rural households often have trouble accessing microcredit. This paper analyzes the influence of financial literacy (FL) on microcredit accessibility in rural households in Tanzania. Methodology: Using a large dataset of Finscope households survey in Tanzania, a binary logit estimation technique was utilized to determine the influence of financial literacy on credit accessing decisions of rural households. In addition, a descriptive analysis was done from the selected sample. Findings: Generally, the analysis showed that financial literacy had a negative and significant effect on the micro-credit accessibility decision of rural households in Tanzania. Education level has a significant positive influence on micro-credit attaining decisions. Practical implication: The outcome of this research is helpful to policymakers and micro-credit institutions as they provide an insight into the influence of financial literacy on microcredit accessibility. The study recommends financial literacy programmes be established in rural areas to enlighten the citizens about the benefit and proper uses of borrowed money. Originality/Value: This paper used actual surveyed data from Tanzanians in all regions. The results are robust to different categories of households and control variables that can also affect micro-credit accessibility decisions.

Climate disasters have become increasingly frequent in India, severely affecting the railway infrastructure every year. Physical damages to railway tracks, bridges, and signaling systems, caused by floods, cyclones, and landslides, are well documented. However, the impact of these disasters on the railway infrastructure was beyond direct physical damages. This paper aimed to explore the impact of climate disasters on railway infrastructure in Northeast India using case study approach. Three cases were studied to analyse the impact of climate disasters on railway infrastructure, including geological disasters and extreme weather. Infrastructure development and operation of railway transport system in Assam, Mizoram, and Manipur proved to be challenging, especially when coping with natural disasters, such as floods, landslides, and earthquakes. This paper found that disruption of railway services was associated with geo-physical structure of the region, which triggered the disaster vulnerability. The results showed that climate disasters had a significant impact on railway infrastructure in Northeast India in many aspects. Formulation and implementation of strategic policies might reduce the disaster risks. Therefore, policymakers and Ministry of Railways, Government of India should consider this possible probability approach over environmental determinism.

This article is the second of the author’s works devoted to a comprehensive study of the economic efficiency of Russian renewable energy (RE) projects. The main goal of this paper is to study the level of influence of political risk on the economic efficiency of RE projects that are implemented in the Russian energy market using a state support program. Fifty-two solar, wind and small hydropower projects, which have received support in the form of a capacity-based support scheme in 2018-2020, were selected as objects of research. The methodological basis of the work was the classical methods of investment analysis and specific industry approach. They were supplemented with the author’s tool for calculating the monetary equivalent of political risk that takes into account the probability of the termination of support from the state. The practice-based assessment utilized the developed scenarios depending on changes in foreign and domestic international credit ratings of the country. The study of the impact of political risk for three stages of RE projects was carried out. Based on the results of the analysis, conclusions were drawn about generally insignificant influence of political risk on the economic efficiency of Russian RE projects. Recommendations for the development of state support programs in the event of the impact of political risks only were generated. The obtained research results are of practical and methodological value. It will be used in studying the impact of other specific risks on the effectiveness of Russian RE projects, as well as in developing recommendations enabling the Russian RE market to give up state support.

Purpose: This study aimed to test the relationship between corporate governance and firm performance, as well as the mediating role of board size and working capital management in the relationship. The sample in this study are manufacturing companies listed on the Indonesia Stock Exchange for the period of 2017-2021. Methodology: The panel regression method was used to analyse research data. In this study, corporate governance was proxied by independent commissioners and ownership structure, while firm performance was measured by ROA and ROE. Meanwhile, the mediating variable, board size was measured by the number of board of directors and working capital management was measured by average payment period. Findings: The results showed that independent commissioners had a significant positive effect as measured by ROA and ROE. While ownership structure also had a significant positive effect as measured by ROA. In addition, working capital management was proven to have a partial mediating role in the relationship between independent commissioners and ROA. However, working capital management was not proven to have a mediating role in the relationship between ownership structure and firm performance, and board size was also not proven to have a mediating role. Practical Implications: This study helps companies understand the significance of corporate board structure and ownership in the effort of achieving a good corporate governance to maximize firm performance. Originality/Value: This study contributes to studies on the effect of corporate governance on firm performance, where the novelty lies in working capital management and board size as mediating variables in the relationship between corporate governance and firm performance.

The attention of many researchers has been drawn to Pythagorean fuzzy information, which involves Pythagorean fuzzy numbers and their aggregation operators. In this study, the concept of the Pythagorean fuzzy set is discussed, along with the Hamacher t-norm and t-conorm operators. Furthermore, novel aggregation operators are developed using the operational rules of the Hamacher t-norm and t-conorm. The primary objective of this article is to develop a multi-attribute decision-making method in a Pythagorean fuzzy environment using Pythagorean fuzzy Hamacher aggregation operators. It is noted that the Hamacher operator, which is a generalization of the algebraic Einstein operator and contains a parameter, is more potent than some existing operators. Finally, an example of an enterprise application software selection problem is presented to demonstrate the proposed method.

Environmental disasters can maliciously affect the property, human lives and entire ecosystems. The magnitude and extent of such a disaster can lead to uncertainty about the measurement and the extent of liability, and how the restoration of the environmental damage will be achieved. Oil spills from tanker vessels constitute the most severe threat to the local and global ecosystem in the shipping industry. when an oil spill incident emerges, it usually spreads rapidly, leading to massive disasters in the local aquatic ecosystem and human property without prompt treatment. This paper assesses the famous accident of Exxon Valdez: (i) to identify and measure the effect of each contributing factor to the accident, (ii) to determine the best solutions to minimise such risks in the future with the implementation of failure mode effect analysis in conjunction with the doctrinal method and at the same time (iii) to propose a new method of accident assessment by combining the doctrinal method with a variation of a well-known risk assessment method.

Due to the speeding up of climate change, there is an urgent need to switch from using fossil fuels to producing energy using renewable energy sources. This change has to happen as soon as feasibly possible. Thus, in this article, to forecast wind speed and wind energy output in Turkey, the Light Gradient Boosting Machine (LightGBM) approach was applied, the hyperparameters of the LightGBM were tuned to the grid search method, and finally some evaluation criteria such as root mean square error and R² were calculated to show the performances of the LightGBM. Fortunately, an R² value of 0.98 for forecasting wind speed was found after 25 s. Additionally, the assessment criterion R² =1 for predicting the production power of the wind turbine was attained after 90 s.

The rapidly increasing energy demand and the inevitable negative effects on the environment caused by fossil-fuelled energy production have made renewable energy technologies increasingly important and preferred among the widely used energy sources during the last decades. Wind energy is one of the leading renewable energy technologies. Wind energy is a carbon-free, environmentally friendly and competitive technology. A step forward in production of wind energy is offshore and onshore wind turbines, with their numerous advantages. Today, the increasing energy needs make onshore and offshore wind turbine applications an increasingly widespread renewable energy source. However, with this change, challenges arise during the operation phases as being associated with the strength of the wind turbines. Potential failures must be known in advance so that they can be dealt with strongly and effectively in the design phase. Damages and failures have a negative effect on the continuation of the operation and cause material and economic impacts. In this paper, the findings from a collection of failure data are presented. The database is available on request. The novelty of this paper is to assess and analyse the damages to wind turbines onshore and offshore in order to reduce the risk of potential failures, damages and collapse of wind turbines. According to the results of these studies and analyses, the database of failures experienced is considered to represent the general failure rate in the industry. This paper brings solutions and suggestions for future studies by pointing out risks and the failure situations that wind turbines are exposed to. It can help innovative solutions with the presentation of a detailed view of risk and failure situations.