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Voltage source inverter-fed permanent magnet synchronous motors (VSI-PMSMs) are widely used in industrial actuation and mechatronic systems in water pumping stations, as well as in the traction of transportation systems (such as electric vehicles and electric trains or ships with electric propulsion). The dynamic model of VSI-PMSMs is multivariable and exhibits complicated nonlinear dynamics. The inverters’ currents, which are generated through a pulsewidth modulation process, are used to control the stator currents of the PMSM, which in turn control the rotational speed of this electric machine. So far, several nonlinear control schemes for VSI-PMSMs have been developed, having as primary objectives the precise tracking of setpoints by the system’s state variables and robustness to parametric changes or external perturbations. However, little has been done for the solution of the associated nonlinear optimal control problem. The purpose of this study/paper is to provide a novel nonlinear optimal control method for VSI-fed three-phase PMSMs.

The present article proposes a nonlinear optimal control approach for VSI-PMSMs. The nonlinear dynamic model of VSI-PMSMs undergoes approximate linearization around a temporary operating point, which is recomputed at each iteration of the control method. This temporary operating point is defined by the present value of the voltage source inverter-fed PMSM state vector and by the last sampled value of the motor’s control input vector. The linearization relies on Taylor series expansion and the calculation of the system’s Jacobian matrices. For the approximately linearized model of the voltage source inverter-fed PMSM, an H-infinity feedback controller is designed. For the computation of the controller’s feedback gains, an algebraic Riccati equation is iteratively solved at each time-step of the control method. The global asymptotic stability properties of the control method are proven through Lyapunov analysis. Finally, to implement state estimation-based control for this system, the H-infinity Kalman filter is proposed as a state observer. The proposed control method achieves fast and accurate tracking of the reference setpoints of the VSI-fed PMSM under moderate variations of the control inputs.

The proposed H-infinity controller provides the solution to the optimal control problem for the VSI-PMSM system under model uncertainty and external perturbations. Actually, this controller represents a min–max differential game taking place between the control inputs, which try to minimize a cost function that contains a quadratic term of the state vector’s tracking error, the model uncertainty, and exogenous disturbance terms, which try to maximize this cost function. To select the feedback gains of the stabilizing feedback controller, an algebraic Riccati equation is repetitively solved at each time-step of the control algorithm. To analyze the stability properties of the control scheme, the Lyapunov method is used. It is proven that the VSI-PMSM loop has the H-infinity tracking performance property, which signifies robustness against model uncertainty and disturbances. Moreover, under moderate conditions, the global asymptotic stability properties of this control scheme are proven. The proposed control method achieves fast tracking of reference setpoints by the VSI-PMSM state variables, while keeping also moderate the variations of the control inputs. The latter property indicates that energy consumption by the VSI-PMSM control loop can be minimized.

The proposed nonlinear optimal control method for the VSI-PMSM system exhibits several advantages: Comparing to global linearization-based control methods, such as Lie algebra-based control or differential flatness theory-based control, the nonlinear optimal control scheme avoids complicated state variable transformations (diffeomorphisms). Besides, its control inputs are applied directly to the initial nonlinear model of the VSI-PMSM system, and thus inverse transformations and the related singularity problems are also avoided. Compared with backstepping control, the nonlinear optimal control scheme does not require the state-space description of the controlled system to be found in the triangular (backstepping integral) form. Compared with sliding-mode control, there is no need to define in an often intuitive manner the sliding surfaces of the controlled system. Finally, compared with local model-based control, the article’s nonlinear optimal control method avoids linearization around multiple operating points and does not need the solution of multiple Riccati equations or LMIs. As a result of this, the nonlinear optimal control method requires less computational effort.

Voltage source inverter-fed permanent magnet synchronous motors (VSI-PMSMs) are widely used in industrial actuation and mechatronic systems in water pumping stations, as well as in the traction of transportation systems (such as electric vehicles and electric trains or ships with electric propulsion), The solution of the associated nonlinear control problem enables reliable and precise functioning of VSI-fd PMSMs. This in turn has a positive impact in all related industrial applications and in tasks of electric traction and propulsion where VSI-fed PMSMs are used. It is particularly important for electric transportation systems and for the wide use of electric vehicles as expected by green policies which aim at deploying electromotion and at achieving the Net Zero objective.

Unlike past approaches, in the new nonlinear optimal control method, linearization is performed around a temporary operating point, which is defined by the present value of the system’s state vector and by the last sampled value of the control input vector and not at points that belong to the desirable trajectory (setpoints). Besides, the Riccati equation, which is used for computing the feedback gains of the controller, is new, as is the global stability proof for this control method. Comparing with nonlinear model predictive control, which is a popular approach for treating the optimal control problem in industry, the new nonlinear optimal (H-infinity) control scheme is of proven global stability, and the convergence of its iterative search for the optimum does not depend on initial conditions and trials with multiple sets of controller parameters. It is also noteworthy that the nonlinear optimal control method is applicable to a wider class of dynamical systems than approaches based on the solution of state-dependent Riccati equations (SDRE). The SDRE approaches can be applied only to dynamical systems that can be transformed to the linear parameter varying form. Besides, the nonlinear optimal control method performs better than nonlinear optimal control schemes which use approximation of the solution of the Hamilton–Jacobi–Bellman equation by Galerkin series expansions.

This paper explores the role that the control system – understood as a set of financial and non-financial mechanisms – introduced by the Ministerial Decree of 15th February 1860 played in promoting the ethical tolerance of prostitution in the Kingdom of Italy.

A qualitative research method was adopted. Specifically, this study draws on literature on accounting and deviant behaviors and on Suchman's theories of legitimation (1995) to interpret empirical evidence collected from archival primary sources as well as secondary sources.

The paper highlights how the accounting mechanisms introduced by the law were molded to limit the serious consequences of prostitution from a public health standpoint and to demonstrate that the State neither profited from prostitution nor used public money to fund it. This should have stimulated ethical tolerance of the law itself and, consequently, of the prostitution that was regulated.

This paper opens a new research avenue in the field of accounting history by exploring the connection between accounting and prostitution. Moreover, unlike the extant literature on accounting and deviant behaviors, this study delves into the role played by accounting mechanisms to promote ethical tolerance rather than to activate normalization processes.

The purpose of this paper is to design an output-feedback algorithm based on low-power observer (LPO), robust chattering-free controller and nonlinear disturbance observer (DO) to achieve trajectory tracking of quadrotor in the Cartesian plane.

To achieve trajectory tracking control, firstly the decoupled rotational and translational model of quadrotor are modified by introducing backstepped state-space variables. In the second step, robust integral sliding mode control is designed based on the proportional-integral-derivative (PID) technique. In the third step, a DO is constructed. In next step, the measurable outputs, i.e. rotational and translational state variables, are used to design the LPO. Finally, in the control algorithm all state variables and its rates are replaced with its estimates obtained using the state-observer.

The finding includes output-feedback control (OFC) algorithm designed by using a LPO. A modified backstepping model for rotational and rotational systems is developed prior to the design of integral sliding mode control based on PID technique. Unlike traditional high-gain observers (HGO), this paper used the LPO for state estimation of quadrotor systems to solve the problem of peaking phenomenon in HGO. Furthermore, a nonlinear DO is designed such that it attenuates disturbance with unknown magnitude and frequency. Moreover, a chattering reduction criterion has been introduced to solve the inherited chattering issue of controllers based on sliding mode technique.

This paper presents input and output data-driven model-free control algorithm. That is, only input and output of the quadrotor model are required to achieve the trajectory tracking control. Therefore, for practical implementation, the number of on-board sensor is reduced.

Although extensive research has been done for designing OFC algorithms for quadrotor, LPO has never been implemented for the rotational and translational state estimations of quadrotor. Furthermore, the mathematical model of rotational and translational systems is modified by using backstepped variables followed by the controller designed using PID and integral sliding mode control technique. Moreover, a DO is developed for attenuation of disturbance with unknown bound, magnitude and frequency.

This paper aims to investigate the prevalence of corruption in Ghana to understand how and why it has turned public procurement into a mere money-making scheme instead of a means to provide needed public goods and services.

The study focuses on Ghana as a case study and mobilizes the monetization of politics lenses. Data are collected via interviews with key officials across the procurement sector (including the government, donors and civil society), documents, documentaries and news articles.

The findings suggest that the increasing costs of elections and political financing coupled with the costs of vote-buying, which has become informally institutionalized, intensify corruption practices and, consequently, turns public procurement into a mere source of cash for political ends. Political appointments and legalized loopholes facilitate this by helping to nullify the safeguard accounting and other control institutions are designed to provide. Likewise, enduring poverty and rising inequality “force” citizens into a vote-buying culture which distorts democratic premises that may drive out unscrupulous politicians; thus, perpetuating capture schemes. Civil society's efforts to remedy these have had little success, and corruption and inequality remain rife.

The main practical implication of the study lies in the need for a gradual demonetization of elections, and the consideration of the fundamental function of public procurement as a policy instrument embedded in economic, social, cultural and environmental plans. Additionally, given the connectedness of the various corruption issues raised, a comprehensive system-based approach in dealing with them would be more effective than a piecemeal approach targeting each issue/problem in isolation.

While extant literature has examined the issue of endemic corruption in developing countries using state capture, few have attempted to explain why it remains enduring, particularly in public procurement. This study, therefore, contributes to the literature on corruption and state capture theoretically and empirically by drawing on monetization of politics from political science to explain why corruption and state capture endure in certain contexts (with Ghana as an illustrative example) which reduce public procurement to a cash-milking scheme.

The primary objective of introducing nonstate ownership into state-owned enterprises (SOEs) is to enhance corporate performance. This study explores how nonstate ownership affects corporate performance, emphasizing agency costs as the primary mechanism.

Using data from 2010 to 2019 for listed SOEs, the authors measure nonstate ownership based on shareholding ratios, control rights and shareholding–control matching. The authors also use fixed-effects and mediation-effects models, with agency costs as the primary mechanism.

Increased nonstate shareholding ratios, stronger control rights and improved shareholding–control matching promote SOE performance. Nonstate shareholding ratios boost performance through resource effects, while control rights and shareholding–control matching promote performance by mitigating agency costs. A heterogeneity analysis indicates stronger effects in local SOEs and highly marketized regions. Moreover, control rights and shareholding–control matching reinforce the positive impact of shareholding ratios on performance.

The mixed-ownership reform of Chinese SOEs aims to optimize shareholding and control structures between state and nonstate shareholders. Therefore, research on the impact of nonstate shareholding ratios, control rights and shareholding–control matching on corporate performance is highly pertinent. However, existing studies have focused on the effects of single factors on performance, without exploration of the economic implications of shareholding–control matching. This study not only prioritizes the optimization of shareholding and control structures but also underscores the importance of granting nonstate shareholders control rights proportionate to their shareholding, providing critical evidence of the value of improving SOEs' ownership structure.

Ethiopia has enacted laws on transparency and disclosure of information in state-owned enterprises (SOEs). However, these laws are not strict enough, with the transparency and disclosure practices disappointing in the country. Thus, this study aims to investigate the legal framework governing transparency and disclosure in SOEs.

This study uses doctrinal, qualitative and comparative approaches. Domestic legal texts are appraised based on the organization for economic co-operation and development Guideline on Corporate Governance of State-owned Enterprises, the World Bank Toolkit on Corporate Governance of State-owned Enterprises and best national practices. This approach has been further corroborated by qualitative analysis of the basic principles of transparency and disclosure.

The finding reveals that the laws on transparency and disclosure do not comply with global practices and are inadequate to ensure transparency and discourse in SOEs. They fail to establish appropriate disclosure frameworks and practices at the SOE and state-ownership entity levels. They also indiscriminately subject enterprises to multiple auditing functions and conflicting responsibilities.

To the author’s knowledge, this study is the first legal literature on transparency and disclosure in Ethiopian SOEs. This study assists the state as owner in reforming the laws and uplifting SOEs from their current unpleasant condition. It can also become a reference for future research.

This study examines the impact of China’s mixed-ownership reform on the innovation of non-state-owned acquirers, with a particular focus on the impact on firms with high financing constraints, low-quality accounting information or less tangible assets.

We use a proprietary dataset of firms listed on the Shanghai and Shenzhen Stock Exchanges to investigate the impact of mixed ownership reform on non-state-owned enterprise (non-SOE) innovation. We employ regression analysis to examine the association between mixed ownership reform and firm innovation.

The study finds that non-state-owned firms can improve innovation by acquiring equity in state-owned enterprises (SOEs) under the reform. Eased financing constraints, lowered financing costs, better access to tax incentives or government subsidies, lowered agency costs, better accounting information quality and more credit loans are underlying the impact. Additionally, cross-ownership connections amongst non-SOE executives and government intervention strengthen the impact, whilst regional marketisation weakens it.

This study adds to the literature on the association between mixed ownership reform and firm innovation by focussing on the conditions under which this impact is stronger. It also sheds light on the policy implications for SOE reforms in emerging economies.

A switching depth controller based on a variable buoyancy system (VBS) is proposed to improve the performance of small autonomous underwater vehicles (AUVs). First, the requirements of VBS for small AUVs are analyzed. Second, a modular VBS with high extensibility and easy integration is proposed based on the concepts of generality and interchangeability. Subsequently, a depth-switching controller is proposed based on the modular VBS, which combines the best features of the linear active disturbance rejection controller and the nonlinear active disturbance rejection controller.

The controller design and endurance of tiny AUVs are challenging because of their low environmental adaptation, limited energy resources and nonlinear dynamics. Traditional and single linear controllers cannot solve these problems efficiently. Although the VBS can improve the endurance of AUVs, the current VBS is not extensible for small AUVs in terms of the differences in individuals and operating environments.

The switching controller’s performance was examined using simulation with water flow and external disturbances, and the controller’s performance was compared in pool experiments. The results show that switching controllers have greater effectiveness, disturbance rejection capability and robustness even in the face of various disturbances.

A high degree of standardization and integration of VBS significantly enhances the performance of small AUVs. This will help expand the market for small AUV applications.

This solution improves the extensibility of the VBS, making it easier to integrate into different models of small AUVs. The device enhances the endurance and maneuverability of the small AUVs by adjusting buoyancy and center of gravity for low-power hovering and pitch angle control.

Ahmet Kuru, in his book, suggests that the explanation for the lack of social and political development in the modern world can be traced back to a historical ‘state-ulama alliance’ from the 11th-century Saljuq empire or earlier. From the perspective of an historian, however, this dating displays some empirical problems. It is certain that the state eventually did gain the upper hand over the Muslim intellectuals, at least in the centre of the Ottoman empire. But the process to that point was different. In this comment, a different explanation is proposed that points instead to two crucial factors: the loss of a homogeneous Muslim state with the fall of the caliphate, and the rise of a unified Muslim world, an umma, through the independence, not subservience, of the class of scholars in the mediaeval period of Islam. Thus, a model is proposed that focuses on two turning points: the replacement of the effective caliphate with a fractious system of sultanates in the mid-tenth century, coinciding with the solidification of Islamic thought in a more strictly regulated form both in theology, law and in Sufism. The second moment is ca. 1500, when the period of political fragmentation comes to an end with the Ottoman state unifying the Middle East, flanked by Morocco and Iran, while challenges to the religious orthodoxy begin to grow at the margins. Such a model thus sees the ulama as actors for change as well as for orthodoxy throughout Muslim history, responding to changing developments in social and political contexts.

The purpose of this study is to examine whether variation in franchising across US states can be explained by differences in state regulatory burdens.

Three years of US state-level panel data is used on measures of franchising activity published by the International Franchise Association. The authors measured variation in regulatory burdens across state governments using the regulatory freedom index, developed by the Cato Institute. Multiple regression analysis was the statistical technique used.

Controlling for state-level per capita personal income, educational attainment, unemployment and share of population identifying as non-white, the authors find states with fewer regulatory burdens for business owners have more franchises and franchise jobs per 100,000 residents, higher franchise output per capita and a larger share of small businesses are franchises. These results were robust to alternative econometric specifications. The results support our hypothesis that states with lower regulatory burdens will have more franchising activity.

Only three years of data are currently available; however, our research provides some practical avenues for managers and policy makers to explore when considering new franchise opportunities or developing policies that impact regulatory burdens for small businesses.

This study contributes to the literature by providing supporting evidence for the relationship between US state institutional factors and franchised small businesses, and it adds a cross-state study to the existing literature using cross-country and cross-city data.