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In this paper, a hybrid flying robot that utilizes water thrust and aerial propeller actuation is proposed and analyzed, with the aim of applications in hazardous tasks in the marine field, such as firefighting, ship inspections, and search and rescue missions. For such tasks, existing solutions like drones and water-powered robots inherited fundamental limitations, making their use ineffective. For instance, drones are constrained by limited flight endurance, while water-powered robots struggle with horizontal motion due to the couplings between translational motions. The proposed hydro-aerodynamic hybrid actuation in this study addresses these significant drawbacks by utilizing water thrust for sustainable vertical propulsion and propeller-based actuation for more controllable horizontal motion. The characteristics and mathematical models of the proposed flying robots are presented in detail. A state feedback controller and a proportional–integral–derivative (PID) controller are designed and implemented in order to govern the proposed robot’s motion. In particular, a linear matrix inequality approach is also proposed for the former design so that a robust performance is ensured. Simulation studies are conducted where a purely water-powered flying robot using a nozzle rotation mechanism is deployed for comparison, to evaluate and validate the feasibility of the flying robot. Results demonstrate that the proposed system exhibits superior performance in terms of stability and tracking, even in the presence of external disturbances.

This paper introduces a novel approach to modeling and control system design for tugboat-assisted operations, such as the docking and rescue of marine vessels. In these scenarios, one or more tugboats push, pull, or guide large vessels to ensure precise and safe maneuvering. Their control systems ensure accurate coordination, vessel positioning, and overall stability, even in the presence of system uncertainties, imperfect control allocation, and ocean disturbances. To address these challenges, a mathematical model of a general tugboat-assisted system is first derived. Then, a new vector of variables is introduced, leading to a modified model representation where the mismatches from the allocation and lower-level tugboat controllers can be realized in the vessel’s motion equation. Thus, the design of a controller can take this aspect into account to enhance the overall system’s performance and stability. Thirdly, a control system design method is proposed, employing a centralized control framework and ensuring a mixed H₂/H∞ performance criterion. Finally, a case study is conducted with a particular tugboat-assisted configuration and the results validate the effectiveness of the control solution.

Nowadays, the demand for high-precision devices is becoming more intense, thanks to the growing complexity and sophistication of modern technology and applications, including microscopy, nanomeasurement and analysis instruments. However, challenges arise because environmental factors such as vibration negatively affect their performance. An active vibration isolation system (AVIS) is one of the most recent solutions for that, but the high degree-of-freedom (DoF) nature results in it strongly suffering from unwanted interactions. Hence, in this paper, a robust decoupling controller is designed to handle the mentioned disadvantages. The system model is first presented, followed by the proposed decoupling techniques, and then, a feedback controller is designed by applying the mixed-sensitivity H∞ control framework. Experimental studies are conducted to investigate the effectiveness of the proposed AVIS and compare it with other systems, namely, a passive vibration isolation system, a proportional–derivative (PD)-controlled AVIS, and a robust controlled AVIS. The robustness and decoupling performance of the proposed controller are guaranteed by suppressing external vibrations and isolating interactions, and, therefore, stabilizing the system.

Forest parameters estimation using polarimetric synthetic aperture radar interferometry (PolInSAR) images is one of the greatest interests in remote sensing applications. Applying the model-based decomposition concept to PolInSAR data opened a new way for forest parameters estimation. However, the method tends to underestimate the forest height due to reflection symmetry assumption and required the numerical solution of nonlinear equation system. In order to overcome these limitations, an improved adaptive decomposition technique with PolInSAR data is proposed. In this approach, an accurate topographical phase and asymmetry volume scattering model are applied to the model-based decomposition technique for polarimetric SAR interferometry image. The accurate topographical phase is first estimated and then used as the initial input parameter to our numerical method. This approach is not only avoiding large error generated by the constant topographical phase in fluctuating forest areas but also improve the accuracy of forest height estimation and the magnitude associated with each mechanism. The performance of proposed method is demonstrated with simulated data from PolSARproSim software and SIR-C/X-SAR spaceborne PolInSAR images over the Tien-Shan areas, China. Experimental results indicate that forest parameters could be effectively extracted by proposed method.

Gallium nitride (GaN), widely known as a wide bandgap semiconductor material, has been mostly employed in high power devices, light emitting diodes (LED), and optoelectronic applications. However, it could be exploited differently due to its piezoelectric properties, such as its higher SAW velocity and strong electromechanical coupling. In this study, we investigated the affect of the presence of a guiding layer made from titanium/gold on the surface acoustic wave propagation of the GaN/sapphire substrate. By fixing the minimum thickness of the guiding layer at 200 nm, we could observe a slight frequency shift compared to the sample without a guiding layer, with the presence of different types of surface mode waves (Rayleigh and Sezawa). This thin guiding layer could be efficient in transforming the propagation modes, acting as a sensing layer for the binding of biomolecules to the gold layer, and influencing the output signal in terms of frequency or velocity. The proposed GaN/sapphire device integrated with a guiding layer could possibly be used as a biosensor and in wireless telecommunication applications.

(1) Autologous chondrocyte implantation (ACI) is a prominent method for treating cartilage damage, but periosteal patches can cause chondrocyte leakage. This study evaluates the potential of a decellularized membrane derived from the cell-produced extracellular matrix of 1-day-old porcine cartilage (pcECM-DM) to act as a substitute for periosteal patches. (2) The interaction between young rabbit chondrocyte cells and pcECM-DM was assessed through cytotoxicity, differentiation, cell viability, cell migration, and adhesive ability. Rabbit chondrocyte cells, cultivated until passage two, were seeded onto a 6 mm diameter membrane. Assessments included DAPI-PKH26 staining, histological staining, live/dead assay, WST-1 assay, and proteomics analysis. (3) Results: DAPI-PKH26 staining showed successful adhesion and the uniform distribution of cells on the membrane. Safranin-O and H&E staining confirmed that the membrane supports chondrocyte adhesion and extracellular matrix production with high cell density and typical chondrocyte morphology. The live/dead assay demonstrated a high proportion of viable cells at 24 and 48 h, with increased cell proliferation over time. The WST-1 assay showed a significant increase in OD450 values, confirming cell proliferation and biocompatibility. Proteomic analysis revealed the significant enrichment of genes associated with extracellular matrix organization, cell adhesion, and cartilage development. (4) Conclusions: This novel biomaterial holds the potential to enhance cartilage regeneration and offer a viable alternative to periosteal patches.

Knowledge management (KM) and innovation (INNO) are often defined as the key drivers for improvement of organizational performance. The purpose of this paper is to explore the impacts of KM on INNO in an academic environment. The results of this study are based on survey data collected during 2017 in 30 public universities equally located in 3 regions of Vietnam. Structural Equation Modelling (SEM) is used to test the hypothesized relationships between KM and INNO. The authors of this study have found that KM comprehensively impacts technical INNO in academic settings and that not all components of KM are directly associated with administrative INNO. Besides enriching the literatures on this rapport, this study is also of value in managerial perspective as it helps increase higher education institutions' (HEIs) knowledge on how to boost their organisational innovativeness, and then enhance performance by engaging in KM activities. A list of measurement scales serving as a checklist for leadership of any HEI desire to practice KM and then boost organizational innovation is provided by this study.

This study investigates the factors motivating workers and their levels of job satisfaction at Eurowindow Vietnam – an FDI company in the furniture industry based in Hochiminh City, Vietnam. Data for this study were collected by a surveying 202 office workers of the company. A Likert-scale response format questionnaire was used to identify employment attitudes and job satisfaction. The research was carried out based on the theoretical aspects of job satisfaction. Cronbach’s alpha and exploratory factor analysis (EFA) were deployed to test the unidimensionality, reliability, and validity of measurement scales. Correlation analysis was carried out to estimate the relation between dependent and independent variables, and within the independent ones. Moreover, multiple regression analysis was adopted to test the hypotheses of the study. The level of job satisfaction was measured by seven dimensions, namely payment, promotion, supervisor, co-workers, work itself, benefits and work environment. The research results showed that work itself, promotion, payment, and supervisor have significant influences on job satisfaction. Findings of this study provide necessary knowledge for the leadership of Eurowindow Vietnam in boosting job satisfaction of their staff. Other FDI enterprises with the same development level may find these results applicable for their organizations. Recommendations for future research are also presented at the end of the study.

In cellular device-to-device (D2D) communication networks, devices can communicate directly with each other without passing through base stations. Access control is an important function of radio resource management which aims to reduce frequency collision and mitigate interference between user’s connections. In this paper, we propose a cluster-based access control (CBAC) mechanism for heterogeneous cellular D2D communication networks with dense device deployment where both the macro base station and smallcell base stations (SBSs) coexist. In the proposed CBAC mechanism, relied on monitoring interference from its neighboring SBSs, each SBS firstly selects their operating bandwidth parts. Then, it jointly al-locates channels and assigns transmission power to smallcell user equipments (SUEs) for their uplink transmissions and users using D2D communications to mitigate their interference to uplink transmissions of macrocell user equipments (MUEs). Through computer simulations, numerical results show that the proposed CBAC mechanism can provide higher network throughput as well as user throughput than those of the network-assisted device-decided scheme proposed in the literature. Simulation results also show that SINR of uplink transmissions of MUEs and D2D communications managed by the MBS can be significantly improved.

Damage in reinforced concrete structures is frequently caused by reinforcement corrosion due to carbonation. Although a wide range of literature contributed to the concrete carbonation consisting of experimental investigations and numerical simulations, research work on a complete numerical model for concrete carbonation prediction with integrated climatic variables (e.g., temperature, relative humidity) is still a challenge. The present paper aims to propose an advanced numerical model to simulate the penetration of carbon dioxide and moisture, diffusion of calcium ions, heat transfer, and porosity modification in concrete material using COMSOL Multiphysics software. Three coupled mass conservation equations of calcium, water, and carbon dioxide are solved together with additional equations regarding the heat transfer, variation of porosity, and content of portlandite and other hydrates and calcites. In this study, the actual temporal variabilities of temperature and relative humidity in Toulouse, France, are used as a case study. The predicted results of portlandite profiles and carbonation depth are compared with the experimental data and discussed to identify the effect of climatic variables on the concrete carbonation.