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Permanent magnet synchronous spherical motors can have wide use in robotics and industrial automation. They enable three-DOF omnidirectional motion of their rotor. They are suitable for several applications, such as actuation in robotics, traction in electric vehicles and use in several automation systems. Unlike conventional synchronous motors, permanent magnet synchronous spherical motors consist of a fixed inner shell, which is the stator, and a rotating outer shell, which is the rotor. Their dynamic model is multivariable and strongly nonlinear. The treatment of the associated control problem is important.

In this paper, the multivariable dynamic model of permanent magnet synchronous spherical motors is analysed, and a nonlinear optimal (H-infinity) control method is developed for it. Differential flatness properties are proven for the spherical motors’ state-space model. Next, the motors’ state-space description undergoes approximate linearization with the use of first-order Taylor series expansion and through the computation of the associated Jacobian matrices. The linearization process takes place at each sampling instance around a time-varying operating point, which is defined by the present value of the motors’ state vector and by the last sampled value of the control input vector. For the approximately linearized model of the permanent magnet synchronous spherical motors, a stabilizing H-infinity feedback controller is designed. To compute the controller’s gains, an algebraic Riccati equation has to be repetitively solved at each time-step of the control algorithm. The global stability properties of the control scheme are proven through Lyapunov analysis. Finally, the performance of the nonlinear optimal control method is compared against a flatness-based control approach implemented in successive loops.

Due to the nonlinear and multivariable structure of the state-space model of spherical motors, the solution of the associated nonlinear control problem is a nontrivial task. In this paper, a novel nonlinear optimal (H-infinity) control approach is proposed for the dynamic model of permanent magnet synchronous spherical motors. The method is based on approximate linearization of the motor’s state-space model with the use of first-order Taylor series expansion and the computation of the associated Jacobian matrices. Furthermore, the paper has introduced a different solution to the nonlinear control problem of the permanent magnet synchronous spherical motor, which is based on flatness-based control implemented in successive loops.

The presented control approaches do not exhibit any limitations, but on the contrary, they have specific advantages. In comparison to global linearization-based control schemes (such as Lie-algebra-based control), they do not make use of complicated changes of state variables (diffeomorphisms) and transformations of the system's state-space description. The computed control inputs are applied directly to the initial nonlinear state-space model of the permanent magnet spherical motor without the intervention of inverse transformations and thus without coming against the risk of singularities.

The motion control problem of spherical motors is nontrivial because of the complicated nonlinear and multivariable dynamics of these electric machines. So far, there have been several attempts to apply nonlinear feedback control to permanent magnet-synchronous spherical motors. However, due to the model’s complexity, few results exist about the associated nonlinear optimal control problem. The proposed nonlinear control methods for permanent magnet synchronous spherical motors make more efficient, precise and reliable the use of such motors in robotics, electric traction and several automation systems.

The treated research topic is central for robotic and industrial automation. Permanent magnet synchronous spherical motors are suitable for several applications, such as actuation in robotics, traction in electric vehicles and use in several automation systems. The solution of the control problem for the nonlinear dynamic model of permanent magnet synchronous spherical motors has many industrial applications and therefore contributes to economic growth and development.

The proposed nonlinear optimal control method is novel compared to past attempts to solve the optimal control problem for nonlinear dynamical systems. 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 inputs 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, and so is the global stability proof for this control method. Compared to 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 which can be transformed into 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. Furthermore, the second control method proposed in this paper, which is flatness-based control in successive loops, is also novel and demonstrates substantial contribution to nonlinear control for robotics and industrial automation.

The unemployment rate (UR) is the leading macroeconomic indicator used in the credit card loss forecasting. COVID-19 pandemic has caused an unprecedented level of volatility in the labor market variables, leading to new challenges to use UR in the credit risk modeling framework. This paper examines the dynamic relationship between the credit card charge-off rate and the unemployment rate over time.

This study uses quarterly observations of charge-off rates on credit card loans of all commercial banks from Q1 1990 to Q4 2020. Univariate, multivariable, machine learning, and regime-switching time series modeling are employed in this research.

The authors decompose UR into two components – temporary and permanent UR. The authors find the spike in UR during COVID-19 is mainly attributed to the surge in temporary layoffs. More importantly, the authors find that the credit card charge-off rate is primarily driven by permanent UR while temporary UR has little predictive power. During recessions, permanent UR seems to be a stronger indicator than total UR. This research highlights the importance of using permanent UR for credit risk modeling.

The findings in the research can be applied to the credit card loss forecasting and CECL reserve models. In addition, this research also has implications for banks, macroeconomic data vendors, regulators, and policymakers.

Despite mounting evidence that job insecurity triggers counterproductive work behavior (CWB), the underlying mechanism within the association in hybrid employment remains unknown. This study aims to investigate turnover intention as a mediator in the association between job insecurity and CWB, as well as the differences between permanent and contract workers concerning the effect of job insecurity on employees’ CWB.

Dyadic data were collected from 213 workers (103 contract and 110 permanent workers) and their supervisors, who were employed in one of the three branches of a Chinese state-owned enterprise, respectively, located in Hunan, Shenyang and Xinjiang.

This study found that job insecurity was positively related to CWB, in which turnover intention acted as a partial mediator. Employment status acted as a moderator between job insecurity and CWB.

First, this study extends the theoretical knowledge concerning how job insecurity activates CWB by identifying turnover intention as a mediating mechanism. To the best of the authors’ knowledge, this is the first study to explore the mediating role of turnover intention in terms of job insecurity and CWB. Second, this research expands the understanding of the relation between job insecurity and CWB by investigating this link in the case of contract workers versus permanent workers. Finally, this paper aims to provide an understanding of why contract workers and permanent workers may differ in their reactions to job insecurity.

The objective of the present study was to investigate the impacts of familiarity with and awareness of Florida as a snowbird destination, and satisfaction with the snowbird experience on Florida's image and on snowbirds' permanent relocation intention to Florida. Additionally, the influence of Florida's image on snowbirds' behavioral intention to move to Florida permanently was investigated.

Data gathered from 304 snowbirds were utilized in employing structural equation modeling to assess the research model.

The study results showed that awareness of and familiarity with Florida as a snowbird destination, and satisfaction with the snowbird experience significantly influenced participants' image perceptions of Florida. In addition, awareness of and familiarity with Florida as a snowbird destination, and participants' image of Florida had a significant influence on snowbirds' intentions to move to Florida permanently.

The findings of the study provide significant insights for destination marketing and management organizations and local policymakers in formulating and enacting policies in snowbird destinations to efficiently address migration trends.

This study is one of the first papers to empirically investigate and successfully construct a comprehensive model that explicate the determinants of snowbird tourists' permanent relocation intention.

I historically compare changes in institutional frameworks creating academic positions linked to temporary employment by analyzing university employment statistics in Chile, Colombia, Germany, and the USA. I find that temporary academic positions were institutionalized through the creation of previously inexistent academic categories called a contrata in Chile, de cátedra in Colombia, “junior professor” without tenure in Germany and “postdoc” in the USA; used in higher education and employment laws since 1989, 1992, 2002, and 1974, respectively. Under institutional frameworks demanding the maximization of students and research, universities have increasingly contracted academics through temporary contracts under rationales that differ between regions. In Colombia and Chile, public university leaders and owners of private universities contract such teaching positions to expand student numbers through lowering costs. In Germany and the USA, employment insecurity is mostly driven by temporary scientific positions under a main rationale of scientific expansion. The share of temporary positions has increased exponentially in Colombia and Germany in recent decades, whereas in the USA there has only been an increase since 2012. Moreover, in Chile, the share of permanent positions has decreased since 2012. The common trend is one of isomorphism of vertical academic structures sharing a pyramidal form, with a wide base of academics working under conditions of contractual insecurity. Such trends follow a rationale for maximization of student numbers as well as administration, and scientific production that is in tension with prioritizing wellbeing and improvement of academics’ working conditions. Yet, in these environments, the institution of tenure in the USA and recent Chilean regulations on accreditation represent mechanisms counteracting precarious employment.

This study aims at presenting the results of the research on the formative and permanent education in adolescence for health professionals of the Municipality of São Paulo. The analysis focuses on the so-called permanent education geared toward health professionals, and seeks to learn about the relation between biomedicine’s construction “of” adolescence and the problems related to teenagers’ health, deemed fundamental for the training of health professionals, from the study of themes related to teenagers’ health as they feature in the Permanent Education Municipal Plans (Planos Municipais de Educação Permanente – PLAMEP, covering the whole of the municipality). Thus the aim is to problematize the social construction, by biomedicine, of adolescence and of the adolescent body, grounded on the understanding of the issues raised in the PLAMEPs and defined as proper “to” adolescence and important for the permanent formation of health professionals. With a methodological approach of both quantitative and qualitative characters, the study holds as empirical reference the Municipal Health Schools of the Municipality of São Paulo and the six Regional Coordination Offices. The study relies, as research techniques, on documental survey (the PLAMEPs); on semi-structured interviews with managers, health representatives, and professionals to whom the activities of permanent education are aimed at; and on notes from the field book. The results now presented refer to the phase of PLAMEPs’ collection and analysis.

This study aims to develop a four-dimensional (4D) textile composite that self-forms upon thermal stimulation while eliminating thermomechanical programming steps by using fused deposition modeling (FDM) 3D printing technology, and tries to refine the product development path for this composite.

Polylactic acid (PLA) printing filaments were deposited on prestretched Lycra-knitted fabric using desktop-level FDM 3D printing technology to construct a three-layer structure of thermally responsive 4D textiles. Subsequently, the effects of different PLA thicknesses and Lycra knit fabric relative elongation on the permanent shape of thermally responsive 4D textiles were studied. Finally, a simulation program was written, and a case in this study demonstrates the usage of thermally responsive 4D textiles and the simulation program to design a wrist support product.

The constructed three-layer structure of PLA and Lycra knitted fabric can self-form under thermal stimulation. The material can also achieve reversible transformation between a permanent shape and multiple temporary shapes. Thinner PLA deposition and higher relative elongation of the Lycra-knitted fabric result in the greater curvature of the permanent shape of the thermally responsive 4D textile. The simulation program accurately predicted the permanent form of multiple basic shapes.

The proposed method enables 4D textiles to directly self-form upon thermal, which helps to improve the manufacturing efficiency of 4D textiles. The thermal responsiveness of the composite also contributes to building an intelligent human–material–environment interaction system.

We empirically assessed the antecedents of subjective well-being at work for French permanent employees.

The methodology includes qualitative and quantitative data analyses. In the first phase, interviews elicited the antecedents of subjective well-being at work among permanent French employees. In the second phase, a questionnaire survey was used to confirm the relevance of the antecedents uncovered in the first phase.

We found 14 distinct elements that influence French employees’ subjective well-being at work: corporate culture, job dissonance, relationships with colleagues, achievement, professional development, relationships with superiors, status, workload, perks, feedback, workspace, diversity and pay. Moreover, we identified discrete antecedents for the three components of subjective well-being at work: work achievement and relationships with superiors and colleagues for positive emotions at work, job dissonance and workload for negative emotions at work and organizational culture and professional development for satisfaction with one’s work.

The original contribution of this study is to have unpacked the black box of the antecedents of subjective well-being in the French workplace and to have uncovered discriminant predictors for each of the three components of subjective well-being at work. Furthermore, we specifically linked each of these three components with their most significant antecedents.

This study aims to minimize the cost and time of blood delivery in the whole blood supply chain network (BSCN) in disaster conditions. In other words, integrating all strategic, tactical and operational decisions of three levels of blood collection, processing and distribution leads to satisfying the demand at the right time.

This paper proposes an integrated BSCN in disaster conditions to consider four categories of facilities, including temporary blood collection centers, field hospitals, main blood processing centers and medical centers, to optimize demand response time appropriately. The proposed model applies the location of all permanent and emergency facilities in three levels: blood collection, processing and distribution. Other essential decisions, including multipurpose facilities, emergency transportation, inventory and allocation, were also used in the model. The LP metric method is applied to solve the proposed bi-objective mathematical model for the BSCN.

The findings show that this model clarifies its efficiency in the total cost and blood delivery time reduction, which results in a low carbon transmission of the blood supply chain.

The researchers proposed an integrated BSCN in disaster conditions to minimize the cost and time of blood delivery. They considered multipurpose capabilities for facilities (e.g. field hospitals are responsible for the three purposes of blood collection, processing and distribution), and so locating permanent and emergency facilities at three levels of blood collection, processing and distribution, support facilities, emergency transportation and traffic on the route with pollution were used to present a new model.

The purpose of this paper is to modernize the generator system of wind turbine concept that not only improves the efficiency and power density but also reduces the system cost making design simpler and less expensive, especially in large-scale production.

This paper presents a new permanent magnet transverse flux generator (PMTFG) for wind energy production. The key feature of its composition is the double armature coil in a semi-closed stator core. The main structural difference of the presented design is the use of double coil in the same space of semi-closed stator core and reduced number of stator pole pairs and rotor magnets from 12/24 to 10/20. 3D simulations are performed using finite element analysis (FEA) to measure induced voltage and magnetic field distribution at no load. The FEA is performed to quantify the change in flux linkage, induced voltage and output power as a function of different speeds and load current.

Results show that PMTFG with double coil configuration has improved electromagnetic performance in terms of flux linkage, induced voltage, output power and efficiency. The power density of 10/20 PMTFG with the double coil is 0.0524 KW/Kg, about an 18% increase compared to the conventional design.

The proposed PMTFG is highly recommended for direct drive applications such as wind power.

Four models are simulated by FEA with single and double coil configuration, and load analysis is performed on all simulated models. Finally, results are compared with conventional PMTFG.