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Bearing friction moments are important factors that affect the vibrations of rotor systems. The bearing friction moments are related to the dimension parameters, lubrication conditions and manufacturing errors of support bearings. This work studies the effects of the bearing friction moments on the vibrations of rotor systems.

The rotor is separated into several shaft elements for formulating a flexible rotor. The time-varying friction moment (TFM) is affected by the time-varying contact loads. The vibrations of FRS from the TFM and Palmgren's friction moment (PFM) calculation methods are compared. Moreover, the effects of the rotor offset and radial clearance on the frequency-amplitude characteristics of FRS are studied.

The TFM method is more consistent with the actual operation mechanisms. The rotor offset and radial clearance can significantly affect the nonlinear vibrations of FRS. This work provides a new reference and research method for the vibration analysis of rotor systems considering the friction effects.

The elastohydrodynamic lubrication (EHL), elastic hysteresis and differential sliding are considered. A flexible rotor system (FRS) dynamic model considering the TFM is proposed. The vibrations of FRS from the TFM calculation method and empirical calculation formula are compared. The effects of the rotor offset and radial clearance on the frequency–amplitude characteristics of FRS are studied.

The performance of financial markets is significantly influenced by the political environment during general elections. This study investigates the effect of general elections on stock market performance in selected African markets.

Prior studies have been inconsistent in determining whether electioneering events negatively or positively influence stock market performance. The study utilized panel data set with annual observations from 1990 to 2020. The generalized method of moments (GMM) is employed to investigate the effect of electioneering and change in government on key stock market performance indicators, including stock market capitalization, stock market turnover ratio and the value of stock traded.

The study finds that electioneering activities generally have a positive impact on the performance of the stock market, whereas a change in government has a negative impact. As a result, the study recommends that stakeholders of the stock market remain vigilant and actively monitor electioneering events to devise and implement effective policies aimed at mitigating political risks during general elections. By adopting these measures, investor confidence can be significantly enhanced, fostering a more robust and secure investment environment.

The study investigates a neglected section of the literature by highlighting not only the effect of elections on stock market indicators but also possible change in government during elections.

This work analyzes, through social-environmental reports, whether banks with higher transparency in social-environmental policies better safeguard financial stability in Brazil.

The analysis is carried out through a panel database analysis of the 42 largest Brazilian banks, representing 98% of the Brazilian financial system. Seeking to avoid spurious results, we followed rigorous methodological standards. Hence, we conducted an empirical analysis using a dynamic panel data model, we used the difference generalized method of moments (D-GMM) and the system generalized method of moments (S-GMM).

The results show that the higher the transparency of social-environmental policies, the lower the chance of possible stress on the financial stability of Brazilian banks. In sum, this study builds evidence that disclosing risks related to policies about sustainability can enhance financial stability. It is essential to highlight that social-environmental transparency does not have as direct objective financial stability.

The manuscript submitted represents an original work that analyzes whether banks with higher transparency in social-environmental policies better safeguard financial stability. Some countries, such as Brazil, have their potential for sustainable policies spotlighted due to their green territory and diverse natural ecosystems. Besides having green potential, Brazil is a developing country with a well-developed financial system. These characteristics make Brazil one of the best laboratories for studying the relationship between transparency in social-environmental policies and financial stability.

The study aims to evaluate the influence of capital structure decisions and asset structure on firms' performance for East African listed nonfinancial firms.

The research is descriptive and employs secondary data from the East African capital markets' websites. The generalized method of moments approach is used to estimate the relationship due to its ability to account for endogeneity problems.

The result shows that capital structure decisions and asset structure strongly influence the firms' performance. When long-term debts, short-term debts and tangible fixed assets increase, the return on total assets increases. An increase in the total debt ratio raises the return on equity (ROE). However, the increase in long-term debt lowers the ROE.

The results will help investors and potential investors decide on a financing policy that maximizes performance. Likewise, governments and other policymakers review the capital markets' frameworks to attract institutional and individual investors to the markets for financial availability and to increase profitability.

The research provides evidence on the influence of capital structure decisions and asset structure on firms' performance. Furthermore, its results contribute to firms' financing policy formulation and the corporate finance literature.

The purpose of this paper is to investigate the influence of macroeconomic cyclical indicators and country governance on bank non-performing loans in African countries.

Data was collected from the 53 African countries covering 2005–2021. The paper develops an empirical model to examine the impact of country governance in reducing macroeconomic cycle-induced adverse effects on bank credit risk. This research estimates Random Effects models and the General Method of Moment to examine the link between microeconomic and governance factors on bank non-performing loans. Stata version 15.1 was used to conduct panel regression analysis.

The findings of the study revealed that the generalized method of moments findings contributes valuable insights into the persistence of NPLs over time and the specific effects of variables on NPL levels. The study findings highlight that the debt-to-GDP ratio, unemployment, regulatory quality, government effectiveness and inflation have significant relationships with NPLs, shedding light on their specific contributions to credit risk dynamics.

The focus on a specific set of determinants for NPLs, which may not capture all the factors that influence NPL levels. Thus, the study did not consider the impact of macroeconomic shocks, such as natural disasters or global economic crises, which can have a significant impact on NPLs.

Policymakers should prioritize maintaining sustainable debt levels, promoting employment growth and controlling inflation rates to mitigate credit risk and reduce nonperforming loans. Also, enhancing regulatory quality and government effectiveness is crucial in ensuring financial stability and minimizing non-performing loans in Africa.

This paper provides a new possible solution to minimise bank non-performing loans risk by examining interactions of country governance regarding the macroeconomic cycle behaviour.

The peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-11-2022-0729

This study aims to examine the role of financial inclusion and institutional factors such as corruption and the rule of law (RL) on the credit risk and stability of banks.

The study considers a sample of 61 developing countries and uses very robust estimation techniques that allow controlling for endogeneity, heteroskedasticity and serial correlation, such as instrumental variables method in two-stage least squares (IV-2SLS), instrumental variables generalized method of moments (IV-GMM), as well as system of generalized methods of moments in two stages (Sys-2GMM).

The results confirm that financial inclusion and strengthening the RL can significantly contribute to reducing credit risk and improving the financial stability of banks; in contrast, the authors find that weak control of corruption aggravates credit risk. In addition, they found that greater competitiveness in the banking sector increases credit risk.

This study supports the need to promote financial inclusion and strengthen institutional factors to improve the stability of the banking sector, as well as promote general well-being in the economy.

This study contributes to the scarce literature by simultaneously using institutional factors such as corruption and the RL and macroeconomic variables such as economic growth and inflation in the relationship between financial inclusion and the banking sector, as well as considering competitiveness as an explanatory factor for banks’ credit risk and stability.

This paper aims to present numerical simulations for a series of flight processes for the postlaunching stage of the “balloon-borne UAV system.” It includes the balloon further ascent motion after airborne launching. In terms of unmanned aerial vehicles (UAVs), the tailspin state and the charge-out process with an anti-tailspin parachute-assisted suspending are analyzed. Then, the authors conduct trajectory optimization simulations for the long-distance gliding process.

The balloon kinematics model and the parachute Kane multibody dynamic model are established. Using steady-state tailspin to reduced-order analysis and achieving change-out simulation by parachute suspension dynamic model. A reentry optimization control problem is developed and the Radau pseudo-spectral method is used to calculate the glide trajectory.

The established dynamic model and trajectory optimization method can effectively simulate the motion process of balloons and UAVs. The system mass reduction for launching UAVs will not cause damage to the balloon structure. The anti-tailspin parachute can reduce the UAV attack angles effectively. The UAV can glide to the designated target position by adjusting the attack angle and sideslip angle. The farthest flight distance after launching from 20 km height is 94 km and the gliding time is 40 min, which demonstrates the potential application advantage of high-altitude launching.

The research content and related conclusions of this article achieve a closed-loop analysis of the flight mission chain for the “balloon-borne UAV system,” which provides simulation references for relevant balloon launching experiments.

This paper establishes a complete set of numerical simulation models and can effectively analyze various postlaunching behaviors.

The purpose of this study is to investigate the relationship between fiscal policy (tax revenues and government expenditure) and economic happiness. The panel data are used from 2012 to 2016 for 18 countries of the Middle East and North Africa (MENA) region.

The study adopted the Barro (1990) model of endogeneity growth to characterize the relationship between fiscal policy and economic happiness. The study estimated the model by using the pooled ordinary least squares method, the fixed effects method and the random-effects method. In addition, the study used the dynamic estimate of this relationship rather than the conventional static estimate through the generalized method of moments’ method. This leads to overcoming the endogeneity problem between the dependent variable and the independent variables.

The main findings indicated that there is a negative and statistically significant relationship between nondistortionary taxes and economic happiness. Also, there is no relationship between public expenditure and economic happiness, whether productive or nonproductive. The results confirmed a positive and significant relationship between other revenues and economic happiness. The current study recommended the diversification of other public revenue sources to increase its contribution to public expenditure financing and the restructuring of the tax system, particularly nondistortionary taxes. These taxes must be replaced by other revenues or by distortionary taxes to increase economic happiness.

The research represents a strong starting base that can help researchers to conduct more studies on economic happiness by using different measures and comparing their results to find out the determinants of happiness. The relationship between economic happiness and fiscal policy with its different aspects requires more studies, especially the relationship between taxes and economic happiness in our region. The study of the relationship between public expenditure and economic happiness according to economic activities can guide decision-makers to direct the expenditure toward economic activities that achieve the happiness of their citizens. Enriching this study requires the availability of fiscal data for the entire MENA region for longer periods, which allow us to divide the countries of the region into petroleum and nonpetroleum countries, but the scarcity of data is one of the limitations of the study.

The governments of MENA countries should diversify other public revenue sources to increase the financing public expenditure by the expense of tax revenues, especially nondistortionary taxes, which would increase the economic happiness of their citizens.

This study is one of the rare studies that investigate the relationship between fiscal policy and economic happiness at the global level. This study contributed to filling the gap of this issue in the MENA region and enriching global literature through the experience of the MENA region. Moreover, this study investigated all aspects of fiscal policy, in contrast to other studies that focused on one of its aspects. The weakness in these studies is because of the lack of correlation between the sources of revenues and the face of their spending.

This paper aims to investigate the effects of cost, revenue and profit efficiency on bank profitability in an emerging economy such as India over the period 1997 to 2017. Additionally, this study examines the effect of efficiency on profitability across different ownership groups for a panel of 70 Indian commercial banks.

In the first stage, using stochastic frontier analysis, we estimate the efficiency scores of cost, revenue and profit over the examined period. In the second stage, this study uses the two-step system generalized-method of moments dynamic panel approach to investigate the impact of several efficiency measures on bank profitability.

Results estimated through and system generalized-method of moments indicate that a higher level of cost, revenue and efficiency significantly improves India's bank profitability. Regarding ownership groups, this study finds that the public sector banks are most cost-efficient compared to private and foreign banks. Other bank-specific, macroeconomic and institutional variables have played a significant role in determining bank profitability.

The findings of the study extend some important policy implications. In light of the rapid decline in bank profitability, banks should focus on increasing the efficiency of their operations. Improvement in profit, cost and revenue efficiency can ameliorate bank performance significantly. Profit efficiency that takes into account both cost and revenue efficiency should be maintained reasonably to prevent the declining pattern of bank profitability that the industry has witnessed over the years.

To the best of the author's knowledge, this study is a fresh piece of research that fulfils an urgent need of investigating the dynamics between bank efficiency and bank profitability in India. In an emerging economy like India, where the banking sector has witnessed substantial structural transformations over the past two decades, such study demands an immediate empirical investigation.

The current developments in the Islamic capital market raise questions about its one of the main objectives of developing the Islamic capital market is to achieve financial inclusion. Despite its policy significance, the empirical literature offers little evidence of the Sukuk-financial inclusion nexus. Thus, this study aims to contribute to the literature by empirically investigating the impacts of Sukuk financing on financial inclusion in most Sukuk-issued financial markets countries.

In this study, the author used a two-step generalized method of moments (GMM) technique to explore the impact of Sukuk financing on financial inclusion in 18 countries using data from 1995 to 2017.

The study's empirical suggest that Sukuk increases financial inclusion and supports the view that Islamic capital markets' development alleviates financing obstacles and also reflects the critical role of the Islamic capital market as a vital contributor to increasing financial inclusion.

The study recommends that Sukuk could be used as a tool to tackle the issue of financial exclusion.

The Sukuk market development creates new job markets through innovative projects. These jobs lead to increased income for the working class, leading to higher employment and stimulating investment and financial inclusion.

This is one of the first studies to investigate the Sukuk-financial inclusion nexus empirically. Additionally, the study has used advanced panel techniques in the context of Sukuk and financial inclusion linkage.

The peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-06-2022-0424