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To provide high torques needed to move a robot’s links, electric actuators are followed by a transmission system with a high transmission rate. For instance, gear ratios of 100:1 are often used in the joints of a robotic manipulator. This results into an actuator with large mechanical impedance (also known as nonback-drivable actuator). This in turn generates high contact forces when collision of the robotic mechanism occur and can cause humans’ injury. Another disadvantage of electric actuators is that they can exhibit overheating when constant torques have to be provided. Comparing to electric actuators, pneumatic actuators have promising properties for robotic applications, due to their low weight, simple mechanical design, low cost and good power-to-weight ratio. Electropneumatically actuated robots usually have better friction properties. Moreover, because of low mechanical impedance, pneumatic robots can provide moderate interaction forces which is important for robotic surgery and rehabilitation tasks. Pneumatic actuators are also well suited for exoskeleton robots. Actuation in exoskeletons should have a fast and accurate response. While electric motors come against high mechanical impedance and the risk of causing injuries, pneumatic actuators exhibit forces and torques which stay within moderate variation ranges. Besides, unlike direct current electric motors, pneumatic actuators have an improved weight-to-power ratio and avoid overheating problems.

The aim of this paper is to analyze a nonlinear optimal control method for electropneumatically actuated robots. A two-link robotic exoskeleton with electropneumatic actuators is considered as a case study. The associated nonlinear and multivariable state-space model is formulated and its differential flatness properties are proven. The dynamic model of the electropneumatic robot is linearized at each sampling instance with the use of first-order Taylor series expansion and through the computation of the associated Jacobian matrices. Within each sampling period, the time-varying linearization point is defined by the present value of the robot’s state vector and by the last sampled value of the control inputs vector. An H-infinity controller is designed for the linearized model of the robot aiming at solving the related optimal control problem under model uncertainties and external perturbations. An algebraic Riccati equation is solved at each time-step of the control method to obtain the stabilizing feedback gains of the H-infinity controller. Through Lyapunov stability analysis, it is proven that the robot’s control scheme satisfies the H-infinity tracking performance conditions which indicate the robustness properties of the control method. Moreover, global asymptotic stability is proven for the control loop. The method achieves fast convergence of the robot’s state variables to the associated reference trajectories, and despite strong nonlinearities in the robot’s dynamics, it keeps moderate the variations of the control inputs.

In this paper, a novel solution has been proposed for the nonlinear optimal control problem of robotic exoskeletons with electropneumatic actuators. As a case study, the dynamic model of a two-link lower-limb robotic exoskeleton with electropneumatic actuators has been considered. The dynamic model of this robotic system undergoes first approximate linearization at each iteration of the control algorithm around a temporary operating point. Within each sampling period, this linearization point is defined by the present value of the robot’s state vector and by the last sampled value of the control inputs vector. The linearization process relies on first-order Taylor series expansion and on the computation of the associated Jacobian matrices. The modeling error which is due to the truncation of higher-order terms from the Taylor series is considered to be a perturbation which is asymptotically compensated by the robustness of the control algorithm. To stabilize the dynamics of the electropneumatically actuated robot and to achieve precise tracking of reference setpoints, an H-infinity (optimal) feedback controller is designed. Actually, the proposed H-infinity controller for the model of the two-link electropneumatically actuated exoskeleton achieves the solution of the associated optimal control problem under model uncertainty and external disturbances. This controller implements a min-max differential game taking place between: (i) the control inputs which try to minimize a cost function which comprises a quadratic term of the state vector’s tracking error and (ii) the model uncertainty and perturbation inputs which try to maximize this cost function. To select the stabilizing feedback gains of this H-infinity controller, an algebraic Riccati equation is being repetitively solved at each time-step of the control method. The global stability properties of the H-infinity control scheme are proven through Lyapunov analysis.

Pneumatic actuators are characterized by high nonlinearities which are due to air compressibility, thermodynamics and valves behavior and thus pneumatic robots require elaborated nonlinear control schemes to ensure their fast and precise positioning. Among the control methods which have been applied to pneumatic robots, one can distinguish differential geometric approaches (Lie algebra-based control, differential flatness theory-based control, nonlinear model predictive control [NMPC], sliding-mode control, backstepping control and multiple models-based fuzzy control). Treating nonlinearities and fault tolerance issues in the control problem of robotic manipulators with electropneumatic actuators has been a nontrivial task.

The novelty of the proposed control method is outlined as follows: preceding results on the use of H-infinity control to nonlinear dynamical systems were limited to the case of affine-in-the-input systems with drift-only dynamics. These results considered that the control inputs gain matrix is not dependent on the values of the system’s state vector. Moreover, in these approaches the linearization was performed around points of the desirable trajectory, whereas in the present paper’s control method the linearization points are related with the value of the state vector at each sampling instance as well as with the last sampled value of the control inputs vector. The Riccati equation which has been proposed for computing the feedback gains of the controller is novel, so is the presented global stability proof through Lyapunov analysis. This paper’s scientific contribution is summarized as follows: (i) the presented nonlinear optimal control method has improved or equally satisfactory performance when compared against other nonlinear control schemes that one can consider for the dynamic model of robots with electropneumatic actuators (such as Lie algebra-based control, differential flatness theory-based control, nonlinear model-based predictive control, sliding-mode control and backstepping control), (ii) it achieves fast and accurate tracking of all reference setpoints, (iii) despite strong nonlinearities in the dynamic model of the robot, it keeps moderate the variations of the control inputs and (iv) unlike the aforementioned alternative control approaches, this paper’s method is the only one that achieves solution of the optimal control problem for electropneumatic robots.

The use of electropneumatic actuation in robots exhibits certain advantages. These can be the improved weight-to-power ratio, the lower mechanical impedance and the avoidance of overheating. At the same time, precise positioning and accurate execution of tasks by electropneumatic robots requires the application of elaborated nonlinear control methods. In this paper, a new nonlinear optimal control method has been developed for electropneumatically actuated robots and has been specifically applied to the dynamic model of a two-link robotic exoskeleton. The benefit from using this paper’s results in industrial and biomedical applications is apparent.

A comparison of the proposed nonlinear optimal (H-infinity) control method against other linear and nonlinear control schemes for electropneumatically actuated robots shows the following: (1) Unlike global linearization-based control approaches, such as Lie algebra-based control and differential flatness theory-based control, the optimal control approach does not rely on complicated transformations (diffeomorphisms) of the system’s state variables. Besides, the computed control inputs are applied directly on the initial nonlinear model of the electropneumatic robot and not on its linearized equivalent. The inverse transformations which are met in global linearization-based control are avoided and consequently one does not come against the related singularity problems. (2) Unlike model predictive control (MPC) and NMPC, the proposed control method is of proven global stability. It is known that MPC is a linear control approach that if applied to the nonlinear dynamics of the electropneumatic robot, the stability of the control loop will be lost. Besides, in NMPC the convergence of its iterative search for an optimum depends on initialization and parameter values selection and consequently the global stability of this control method cannot be always assured. (3) Unlike sliding-mode control and backstepping control, the proposed optimal control method does not require the state-space description of the system to be found in a specific form. About sliding-mode control, it is known that when the controlled system is not found in the input-output linearized form the definition of the sliding surface can be an intuitive procedure. About backstepping control, it is known that it cannot be directly applied to a dynamical system if the related state-space model is not found in the triangular (backstepping integral) form. (4) Unlike PID control, the proposed nonlinear optimal control method is of proven global stability, the selection of the controller’s parameters does not rely on a heuristic tuning procedure, and the stability of the control loop is assured in the case of changes of operating points. (5) Unlike multiple local models-based control, the nonlinear optimal control method uses only one linearization point and needs the solution of only one Riccati equation so as to compute the stabilizing feedback gains of the controller. Consequently, in terms of computation load the proposed control method for the electropneumatic actuator’s dynamics is much more efficient.

The purpose of this paper is to examine the careers of skilled migrants from Indian Punjab. This study complicates the normalization of skilled migration as a “win‐win” situation by examining the career trajectories of skilled migrants from the Indian Punjab who are trying to establish themselves in Britain.

The paper examines 20 life history interviews undertaken with skilled migrants from the Indian Punjab to Britain, in IT, media, law and hospitality industries, health and welfare professionals, and student migrants.

Skilled migrants were able to migrate on their own auspices through migration economies in Punjab. Once in Britain, however, they were directed to universities and labour markets in which they were not able to use their skills. They experienced under‐employment, devaluation of their qualifications and downward mobility, which forced them into ethnic and gendered markets within their home networks and created ambivalence about migrant success and issues of return.

The study emphasizes the need to take a transnational lens when looking at skilled migration, address how migrants’ career trajectories are limited by racism, anti‐immigration sentiment and gender inequality, and consider temporality and uncertainty.

The paper raises questions concerning the ways in which rapidly changing “managed migration” policies in Britain have burdened individual migrants.

The economic literature on labor migration has incorporated insights from various disciplines with regard to content and method, although the representation of migrants has not fully moved away from the neoliberal, market-dominated framework. This paper addresses the issue of women migrant workers using the particular example of Sri Lankan migrant women workers to the Middle East. It aims to highlight the need for more diversity in economic research without which conceptual representation, as well as empirical reach, is limited.

After a brief overview of the representation of migrants in economic literature, I develop the concept of vulnerability. I refer to qualitative and quantitative analyses on Sri Lankan migrant women workers to the Middle East from a variety of disciplines in order to differentiate the “vulnerable,” that is, the workers in need of protection, from the “vulnerabilities.” The latter concept refers to the debilitating effects on workers, produced by market forces, which are often perpetuated by underlying assumptions, as well as policies. A broader, inter-disciplinary perspective, which considers the agency of women, can go a long way toward removing some of the limitations and preconceptions ingrained in most economic representation. This in turn could help to improve the protection of the vulnerable and empower them to better face market forces.

The purpose of this paper is to demonstrate how public health and systems science methods can be combined to examine the structure and behavior of Afghanistan’s routine childhood immunization system to identify the pathways through which health system readiness to deliver vaccination services may extend beyond immunization outcomes.

Using findings from an ecological study of Afghanistan’s immunization system and a literature review on immunization program delivery, the routine immunization system was mapped using causal loop diagrams. Next, a stock-and-flow diagram was developed and translated to a system dynamics (SD) model for a system-confirmatory exercise. Data are from annual health facility assessments and two cross-sectional household surveys. SD model results were compared with measured readiness and service outcomes to confirm system structure.

Readiness and demand-side components were associated with improved immunization coverage. The routine immunization system was mapped using four interlinking readiness subsystems. In the SD model, health worker capacity and demand-side factors significantly affected maternal health service coverage. System readiness components affected their future measures mostly negatively, which may indicate that the reinforcing feedback drives current system-structured behavior.

The models developed herein are useful to explore the potential impact of candidate interventions on service outcomes. This paper documents the process through which public health and systems investigators can collaboratively develop models that represent the feedback-driven behavior of health systems. Such models allow for more realistically addressing health policy and systems-level research questions.

The aim of this paper is to present a conceptual model on foreign-born health care workers from developing countries working in the US. The model covers their motivations for migration, the consequences in terms of the inequality and exclusion they may experience and the role of institutional responses at micro-, macro- and meso-level of intervention.

The paper is based on: (1) in-depth review of key literature studies on the foundation theories of international migration including sociology, economics, anthropology, psychology and human resource management, (2) analysis of theoretical approaches to medical migration across disciplines, (3) analysis of the international and national documentary sources of micro-, macro- and meso-level policies on migration and (4) analysis of evidence on best practices, solutions and aspirational changes across different levels of institutions.

(1) Migration of international medical graduates (IMGs) from developing countries to the US can be explained from a micro-, macro- and meso-level of analysis. (2) IMGs who identify as racial/ethnic minorities may experience unfair discrimination differently than their US-born counterparts. (3) Although political/legislative remedies have had some successes, proactive initiatives will be needed alongside enforcement strategies to achieve equity and inclusion. (4) While diversity management initiatives abound in organizations, those designed for the benefit of IMGs from developing countries are rare. (5) Professional identity groups and some nonprofits may challenge structural inequities, but these have not yet achieved economies of scale.

Although it is well-documented in the US health care literature how ethnic/racial minorities are unfairly disadvantaged in work and career, the studies are rarely disaggregated according to sub-groups (e.g. non-White IMGs and US-born MGs). The implication is that Black IMG immigrants have been overlooked by the predominant narratives of native-born, Black experiences. In placing the realities of native-born Blacks on the entire Black population in America, data have ignored and undermined the diverse histories, identities and experiences of this heterogeneous group.

An awareness of the challenges IMGs from developing countries face have implications for managerial decisions regarding recruitment and selection. Besides their medical qualifications, IMGs from developing countries offer employers additional qualities that are critical to success in health care delivery. Considering organizations traditionally favor White immigrants from Northern and Southern Europe, IMGs from developed countries migrate to the US under relatively easier circumstances. It is important to balance the scale in the decision-making process by including an evaluation of migration antecedents in comprehensive selection criteria.

The unfair discrimination faced by IMGs who identify as racial/ethnic minority are multilayered and will affect them in ways that are different compared to their US-born counterparts. In effect, researchers need to make this distinction in research on racial discrimination. Since IMGs are not all uniformly impacted by unfair discrimination, organization-wide audits should be in tune with issues that are of concerns to IMGs who identify as racial/ethnic minorities. Likewise, diversity management strategies should be more inclusive and should not ignore the intersectionality of race/ethnicity, nationality, country of qualification and gender.

Immigrant health care workers from developing countries are integral to the health care industry in the United States. They make up a significant proportion of all workers in the health care industry in the US. Although the literature is replete with studies on immigrant health care workers as a whole, research has rarely focused on immigrant health care workers from developing countries. The paper makes a valuable contribution in drawing attention to this underappreciated group, given their critical role in the ongoing pandemic and the need for the US health industry to retain their services to remain viable in the future.

Purpose: Although the transnational mobility of youth is prevalent across the globe, the policies and strategies used by developing countries to promote youths’ transnational mobility remains unclear. This chapter aims to discuss a few emerging trends and concerns related to youth transnational mobility and human capital accumulation. It focuses on the specific case of youth transnational migration from India. As such, this chapter considers the factors that have led to the construction of aspirations for transnational migration among Indian youth.

Study approach: In this chapter, we examine youth transnational mobility by synthesising the major literature available in the area of globalisation and transnational migration in the developing countries context. The study also incorporates the policy debates and secondary data evidence in these domains to substantiate the arguments.

Findings: Mainly focussing on the internal state of affairs of India, this work highlights three critical issues (a) new norms and practices of human capital accumulation within India’s knowledge economy; (b) understanding state and formal-informal ‘commoditised’ market dynamics in the changing aspirations for global human capital formation, specifically through transnational migration; and (c) examining the upshots of youth transnational mobility in terms of the production of relatively new forms of caste and class inequalities within Indian society.

Originality: This conceptual piece of work is an initial foray to unpack the complexities of Indian youths’ migration for specialised forms of human capital accumulation in a global landscape. The study motivates future policy-oriented interdisciplinary research on education and transnational mobility, specifically in empirical research projects.

The purpose of this paper is to understand challenges facing organizations in the twenty-first century and address these challenges through suggesting future leadership development based on relevant leadership theories, which would motivate and guide future research directions in a streamlined manner.

The present study adopted the exploratory literature review, using the integrative method, to review the theoretical and empirical literature on leadership development published since the 2000s, primarily focusing on research published in the Journal of Management Development.

The findings of the current review confirmed that leadership theories are the base for leadership development theories, particularly if the purpose is to address and overcome the current challenges facing organizations. The authors suggest that leadership theories and leadership development theories do not exist in isolation from one another, nor do they exist in isolation from challenges facing organizations.

This review does not cover all studies before the 2000s nor other journals in the field of leadership.

Given that most organizations are suffering from one or more of the following issues: sexual scandals, unethical behaviors, individualism, crises and a low level of performance or productivity, the development of particular leadership skills has become a priority. This study is one of few studies guiding both future leadership development research directions and leadership development initiatives.

The purpose of this paper is to formally assess the training program received by information studies graduate students and the reference services they provided at a research-intensive university.

A qualitative content analysis was used to evaluate if graduate students incorporated the training they received in their provision of reference services. The students’ virtual reference transcripts were coded to identify the level of questions asked, if a reference interview occurred and if different teaching methods were used by the students in their interactions. The in-person reference transactions recorded by the students were coded for the level of questions asked.

The main findings demonstrate a low frequency of reference interviews in chat interactions with a presence in only 23 per cent of instances while showing that instructional methods are highly used by graduate student reference assistants and are present in 66 per cent of chat conversations.

This study is of interest to academic libraries who wish to partner with information studies programs and schools to offer graduate students valuable work experience. It aims to show the value that graduate students can bring to reference services. Furthermore, it highlights the importance of continuously developing training programs and assessing the performance of graduate students working in these roles.

The purpose of this article is to study the link between mean shift and inflation coefficient when the underlying null hypothesis is rejected in the analysis of variance (ANOVA) application after the preliminary test on the model specification.

A new approach is proposed to study the link between mean shift and inflation coefficient when the underlying null hypothesis is rejected in the ANOVA application. First, we determine this relationship from the general perspective of Six Sigma methodology under the normality assumption. Then, the approach is extended to a balanced two-stage nested design with a random effects model in which a preliminary test is used to fix the main test statistic.

The features of mean-shifted and inflated (but centred) processes with the same specification limits from the perspective of Six Sigma are studied. The shift and inflation coefficients are derived for the two-stage balanced ANOVA model. We obtained good predictions for the process shift, given the inflation coefficient, which has been demonstrated using numerical results and applied to case studies. It is understood that the proposed method may be used as a tool to obtain an efficient variance estimator under mean shift.

In this work, as a new research approach, we studied the link between mean shift and inflation coefficients when the underlying null hypothesis is rejected in the ANOVA. Derivations for these coefficients are presented. The results when the null hypothesis is accepted are also studied. This needs the help of preliminary tests to decide on the model assumptions, and hence the researchers are expected to be familiar with the application of preliminary tests.

After studying the proposed approach with extensive numerical results, we have provided two practical examples that demonstrate the significance of the approach for real-time practitioners. The practitioners are expected to take additional care before deciding on the model assumptions by applying preliminary tests.

The proposed approach is original in the sense that there have been no similar approaches existing in the literature that combine Six Sigma and preliminary tests in ANOVA applications.