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This paper aims to propose a hybrid force/position controller based on the adaptive variable impedance.

First, the working space is divided into a force control subspace and a position subspace, the force control subspace adopts the position impedance control strategy. At the same time, the contact force model between the robot and the surface is analyzed in this space. Second, based on the traditional position impedance, the model reference adaptive control is introduced to provide an accurate reference position for the impedance controller. Then, the BP neural network is used to adjust the impedance parameters online.

The experimental results show that compared with the traditional PI control method, the proposed method has a higher flexibility, the dynamic response accommodation time is reduced by 7.688 s and the steady-state error is reduced by 30.531%. The overshoot of the contact force between the end of robot and the workpiece is reduced by 34.325% comparing with the fixed impedance control method.

The proposed control method compares with a hybrid force/position based on PI control method and a position fixed impedance control method by simulation and experiment.

The adaptive variable impedance control method improves accuracy of force tracking and solves the problem of the large surfaces with robot grinding often over-polished at the protrusion and under-polished at the concave.

For nanostores, striving to become the community group-buying leader is gaining prominence. This paper aims to construct Hotelling linear models to investigate whether nanostores should be registered as leaders and their decisions in a competitive environment.

This paper constructs three Hotelling linear models: neither nanostore registers as community leader, only one nanostore registers as community leader and both nanostores register as community leader. The competitive operation strategies of two general nanostores under three scenarios are solved.

The study finds that nanostores without a cost advantage may benefit from being the first leader. The nanostore's preferred decisions depend on the investment cost parameters of its own and competitors which may lead to market share competition. Furthermore, consumers' sensitivity to community group-buying service has a negative effect on nanostores' profit.

The study is one of the few to consider the competition between community leaders. Besides, the study considers that the utilities functions of consumers are concurrently impacted by the service decisions, along with the price in different nanostores. It can provide nanostores useful implications in the dynamic industry.

Visual feedback control is a promising solution for robots work in unstructured environments, and this is accomplished by estimation of the time derivative relationship between the image features and the robot moving. While some of the drawbacks associated with most visual servoing (VS) approaches include the vision–motor mapping computation and the robots’ dynamic performance, the problem of designing optimal and more effective VS systems still remains challenging. Thus, the purpose of this paper is to propose and evaluate the VS method for robots in an unstructured environment.

This paper presents a new model-free VS control of a robotic manipulator, for which an adaptive estimator aid by network learning is proposed using online estimation of the vision–motor mapping relationship in an environment without the knowledge of statistical noise. Based on the adaptive estimator, a model-free VS schema was constructed by introducing an active disturbance rejection control (ADRC). In our schema, the VS system was designed independently of the robot kinematic model.

The various simulations and experiments were conducted to verify the proposed approach by using an eye-in-hand robot manipulator without calibration and vision depth information, which can improve the autonomous maneuverability of the robot and also allow the robot to adapt its motion according to the image feature changes in real time. In the current method, the image feature trajectory was stable in the camera field range, and the robot’s end motion trajectory did not exhibit shock retreat. The results showed that the steady-state errors of image features was within 19.74 pixels, the robot positioning was stable within 1.53 mm and 0.0373 rad and the convergence rate of the control system was less than 7.21 s in real grasping tasks.

Compared with traditional Kalman filtering for image-based VS and position-based VS methods, this paper adopts the model-free VS method based on the adaptive mapping estimator combination with the ADRC controller, which is effective for improving the dynamic performance of robot systems. The proposed model-free VS schema is suitable for robots’ grasping manipulation in unstructured environments.

This study aims to examine the plane wave reflection problem in micropolar orthotropic magneto-thermoelastic half space, considering the influence of impedance as a boundary in a nonlocal elasticity.

This study presents the novel formulation of governing partial differential equations for micropolar orthotropic medium with impact of nonlocal thermo-elasticity under magnetic field.

This study provides the numerical results validation for a particular numerical data and expression for the amplitude ratios of reflected waves and identifies the existence of four different waves, namely, quasi longitudinal displacement qCLD-wave, quasi thermal wave qCT-wave, quasi transverse displacement qCTD-wave and quasi-transverse micro-rotational qCTM-wave. The study derives the velocity equation giving the speed and phase velocity of these waves. The study also shows that the small-scale size effect gives significant impact on phase velocity.

The graphical analysis examines the variation of speeds and coefficients of attenuation of these waves due to frequency, magnetic field and nonlocal parameters. Also, significant conclusions on the variation of reflection coefficient against nonlocal parameter, frequency, impedance parameter and angle of incidence are provided graphically.

The creation of more effective micropolar orthotropic anisotropic materials which are very useful in the daily life and their applications in earth science are greatly impacted by the findings of this study.

The authors of the submitted document initiated and produced it collectively, with equal contributions from all members.

This study aims to deepen the knowledge concerning the metal fused filament fabrication technology through an analysis of the printing parameters of a commercial 316L stainless steel filament and their influence on the porosity and mechanical properties of the printed parts. It also investigates the feasibility of manufacturing complex geometries, including strut-and-node and triply periodic minimal surface lattices.

A three-step experimental campaign was carried out. Firstly, the printing parameters were evaluated by analysing the green parts: porosity and density measurements were used to define the best printing profile. Then, the microstructure and porosity of the sintered parts were investigated using light optical and scanning electron microscopy, while their mechanical properties were obtained through tensile tests. Finally, manufacturability limits were explored with reference samples and cellular structures having different topologies.

The choice of printing parameters drastically influences the porosity of green parts. A printing profile which enables reaching a relative density above 99% has been identified. However, voids characterise the sintered components in parallel planes at the interfaces between layers, which inevitably affect their mechanical properties. Lattice structures and complex geometries can be effectively printed, debinded, and sintered if properly dimensioned to fulfil printing constraints.

This study provides an extensive analysis of the printing parameters for the 316L filament used and an in-depth investigation of the potential of the metal fused filament fabrication technology in printing lightweight structures.

This study aims to examine the impact of gamification on the five dimensions of meaningful learning (i.e. cooperative, active, authentic, constructive and intentional learning) and undergraduate student performance taking online lessons.

Therefore, the authors conducted an experiment among undergraduate students taking online classes at the Mechanical and Electrical Engineering School at a public university during the COVID-19 pandemic. The experiment included one control and two observation groups using gamification (Golden Points). Qualitative and quantitative analyses were performed.

Results showed that gamification significantly affects meaningful learning and impacts student performance in online courses.

This study was limited to a single topic in a six-month course at a public university. Additional research is required to continue examining the impact of gamification in higher education institutions with different format courses and in other organisational sectors.

This study aims to evaluate the relationship between integrated reporting and management’s opportunistic behavior (i.e., accrual and real earnings management) and the moderating role of firm complexity.

Data of firms at the Johannesburg Stock Exchange were collected and analyzed. The Johannesburg Stock Exchange is currently the primary exchange that mandates the practice of integrated reporting. Regression estimation models and robustness tests were applied to the analysis.

This study concludes that integrated reporting quality reduces firms’ accrual and real earnings management practices. It further concludes that the significant negative effect of integrated reporting quality on firms’ earnings management practices is impeded by higher firm complexity.

This study enhances the literature on the behavioral effect of a combined financial and sustainability disclosure practice on both accrual and real earnings management, specifically targeting South Africa’s listed companies – the primary market currently mandates integrated reporting practice.

This study aims to examine the cilia-driven flow of magnetohydrodynamics (MHD) non-Newtonian fluid through a porous medium. The Jeffrey fluid model is taken into account. The fluid motion in a two-dimensional symmetric channel emphasizes the dominance of viscous properties over inertial properties in the context of long wavelength and low Reynolds number approximations.

An integrated numerical and analytic results are obtained by hybrid approach. A statistical method analysis of variance along with response surface methodology is used. Sensitivity analysis is used to validate the accuracy of nondimensional numbers.

The impact of various flow parameters is presented graphically and in numerical tables. It is noted that the velocity slip parameter is the most sensitive flow parameter in velocity and relaxation to retardation time ratio in temperature.

A model on cilia-generated flow of MHD non-Newtonian Jeffrey fluid is proposed.

The COVID-19 pandemic has amplified the importance of effectively leading a remote workforce in volatile, uncertain, complex and ambiguous (VUCA) environments. This study examines the effectiveness of transformational–transactional leadership (Full-Range Leadership Model, FRLM) and its recent extension of instrumental leadership (eFRLM) in remote work contexts.

We surveyed 529 remote working followers, providing perceptions on (1) their leaders’ manifestation of eFRLM dimensions and factors, (2) their leaders’ leadership effectiveness and (3) their organizational environment as VUCA.

Results show that instrumental leadership represents a strongly effective leadership dimension in remote work contexts, explaining unique variance beyond transformational–transactional leadership. Moreover, VUCA environments moderated the association between eFRLM leadership behaviors and leadership effectiveness, with instrumental leadership being particularly effective in more pronounced VUCA environments and transformational–transactional leadership being less effective.

Overall, instrumental leadership appears crucial to consider when predicting leadership effectiveness in virtual and uncertain contexts.

The aim of this study was to determine the effect of anxiety levels of adults on their nutritional status during the COVID-19 pandemic in Kayseri province, Turkey.

A total of 898 adults consisting of 479 individuals with and 419 individuals without a positive diagnosis of COVID-19 were included in the study. The individuals’ socio-demographic characteristics, health status, nutritional habits, anthropometric measurement and Fear of COVID-19 Scale (FCV-19S) information were obtained online.

The mean FCV-19S score of the participants was 17.49 ± 6.02. FCV-19S score was higher in those who reduced their consumption of protein sources compared to those who did not change and those who increased (p < 0.001). It was determined that FCV-19S scores of participants who increased their consumption of fruit/vegetables, sweets and sugar were higher than those who did not change their consumption of such items (p = 0.007). The FCV-19S scores of individuals who did not change their onion/garlic and snack consumption were lower than those who decreased or increased the consumption of these nutrients (p = 0.001, p = 0.002).

Education programs can be organized especially targeting vulnerable populations, such as women, individuals with chronic diseases and those experiencing COVID-19 symptoms. These programs can be conducted by dietitians and psychologists in collaboration, focusing on promoting healthy eating habits and coping strategies during stressful times.

It was determined that those who changed their nutrition habits during the COVID-19 pandemic had higher fear levels than those who did not. Individuals with high fear paid more attention to healthy nutrition than individuals without fear.