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Herein we report a square-like D4h H©K4H4− anion with one planar tetracoordinate hydrogen (ptH) center, which is the global minimum (GM) structure and possesses good dynamic stability. The planar structure of the system is preserved by four peripheral K–H–K three-center two-electron (3c-2e) σ bonds together with one 5c-2e σ bond over the HK4 core. The multicenter ionic bonds dominate the stability of ptH, while the contribution of qualitative σ aromaticity is extremely limited. [ABSTRACT FROM AUTHOR]

The nitro groups are introduced into 4-(1H-1,2,4-triazol-1-yl) pyrimidine to substitute the hydrogen atoms successively, through which a total of 31 derivatives are constructed to look for high energy density compounds (HEDCs). To probe the thermal stabilities, the heats of formation (HOFs) are calculated by using the G3MP2 method. To explore the dynamic stability, the natural bond orbital (NBO) analysis is performed to confirm the trigger bond, for which the bond dissociation energy is calculated using the B3PW91 method with the 6-311 + G(d,p) basis set. Furthermore, the detonation velocity (D), the detonation pressure (P), the molecular density (ρ), the explosive heat (Q), and character height (H50) are also predicted. Based on our calculation, it is confirmed that D1, D2, D5, and E are potential high-energy-density compounds with sufficient stability and excellent detonation performance. [ABSTRACT FROM AUTHOR]

In this study, the stability and viscosity of four different nanoparticles are discussed in conjunction with the physical properties of these nanoparticles. The aim is to provide guidance for nanoparticle selection in future nanofluid applications. Additionally, our goal is to examine hybrid nanofluids in comparison to single nanofluids, exploring their potential benefits and evaluating their industrial applications. A two-stage approach was employed, using ethylene glycol (EG) as a base fluid, to create these nanofluids. Single nanofluids were formed with SiO2, TiO2, MWCNT, and ZnO nanoparticles at 0.1%, 0.5%, and 1% volume concentrations. Additionally, binary (SiO2–TiO2/EG), ternary (SiO2–TiO2–MWCNT/EG), and quaternary (SiO2–TiO2–MWCNT–ZnO/EG) hybrid nanofluids were formed with 0.1% volume concentrations. The dynamic viscosity of all nanofluids was evaluated over the temperature range of 20–50 °C. Analysis of nanofluids was extended by characterization studies using field emission transmission electron microscopy (FE-SEM), field emission scanning electron microscopy (FE-TEM), Zeta potential testing, and visual inspection. SiO2 nanoparticles exhibited the greatest stability, remaining in suspension for more than 28 days without sedimentation, while ZnO nanoparticles were the least stable, collapsing in < 7 days. Compared to ethylene glycol, ZnO/EG had the most increased viscosity (42.79%) at 20 °C and a 1% volume concentration. However, SiO2–TiO2–MWCNT/EG showed the largest decrease in viscosity (9.99%) at 20 °C. Hybrid nanofluids exhibit better viscosity performance compared to their base fluids and single nanofluids, enhancing the thermal efficiency of these heat transfer fluids. Additionally, this study is groundbreaking research as it emphasizes the efficiency of hybrid nanofluids as well as introducing quaternary nanofluids to the literature. [ABSTRACT FROM AUTHOR]

Milling a thin-walled curved structure is prone to chattering and cannot guarantee the quality of the machined surface. Studies of milling thin-walled curved structures on metallic parts have been investigated for years, while in terms of carbon fiber-reinforced plastic (CFRP) parts with a strong anisotropic nature, the tool-material cutting interactions would change at any positions and directions, resulting in a significant change in dynamic cutting force and more complex chatter. Thus, further dynamic modeling should be modified to predict machining chattering accurately. This study introduced the anisotropic and laminated features of CFRP into the machining dynamic model and stability domain solution prediction in milling CFRP. A dynamic cutting force model under the regenerating mechanism was first proposed by considering the instantaneous fiber cutting angle and the cutting edge length of the immediate contact micro-element with the same fiber layer. Moreover, the dynamic model for milling this CFRP workpiece was established based on the dynamic cutting force model and dynamic characteristics of the workpiece. The stability lobe diagram was drawn, and the stable cutting regions were obtained for milling CFRP. Also, experimental verifications were conducted, and the chattering and steady machining conditions were well predicted. Compared with the stable area obtained without considering the anisotropic characteristic of CFRP, the expected maximum peak value of the stable region increased by 49.7%, proving the accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

In order to enhance the synchronization of welding robot arms and improve welding quality, this study proposes a fuzzy PID-based improved deviation coupling multi-axis synchronous control method. Firstly, in response to the intricacies inherent in the compensation mechanism of the deviation coupling control structure and the substantial volume of system computation, the integration of average speed and sub-average speed is proposed to optimize the speed compensator. This integration aims to mitigate speed synchronization errors, minimize synchronization adjustment time, and elevate overall system synchronization performance. Moreover, the fuzzy PID algorithm is employed to design the controller to realize the single-motor adaptive control, leading to improvement in both system stability and dynamic response performance. Finally, a simulation model for six-axis synchronization control and an experimental platform were developed. Both simulation and experimental results demonstrate that the improved deviation coupling control method exhibits superior synchronization performance. The proposed multi-axis synchronous control method effectively heightens the synchronous performance of the six-degrees-of-freedom robotic arm. [ABSTRACT FROM AUTHOR]

This study investigates the structural stability and electronic properties of α‐MX nanothreads and β‐MX nanosheets (M=Au, Ag; X=S, Se) using density functional theory. Our findings confirm the thermal and dynamic stability of all nanostructures, with β‐MX phases being more stable than α‐MX, albeit with minimal energy differences between the two phases. Electron localization analysis reveals predominantly ionic bonding character between M (Ag and Au) and X (S and Se) atoms. All the phase exhibits metallophilic interactions (Argentophilic and Aurophilic), with α‐MX nanothreads demonstrating a higher level of interaction compared to β‐MX nanosheets, attributed to the curvature inherent in the nanothreads. Significantly, these interactions are effectively small and do not compromise the relative stability between the α‐MX and β‐MX phases. Additionally, both α‐MX and β‐MX structures exhibit characteristics of indirect bandgap semiconductor behaviour. The band gap values do not significantly differ between α‐MX and β‐MX phases. Fermi analysis reveals that α‐MX phases exhibit small effective electron masses and large hole mobility along the uniaxial direction. These findings suggest promising prospects for α‐MX nanothreads as 1D semiconductors in nano‐electronics and nano‐optoelectronics applications in the future. [ABSTRACT FROM AUTHOR]

AbstractA time-periodic axial force acting on a continuous structure can be destabilized by parametric excitation. Moreover, it is capable of increasing the equivalent damping and shortening the transient vibrations. In this work, this concept is extended, and dynamic stability of a Mindlin-Reissner plate is analyzed. The FE formulation for the four-node plate element is derived by employing the variational approach including the action of an axial force. The stability of the time-periodic system is evaluated both numerically and analytically, using Floquet theory and first-order approximation based on the averaging method, respectively. The influence of plate length, thickness, and aspect ratio on dynamic stability is highlighted. It is demonstrated that the instability tongue at a parametric combination resonance frequency of the summation type is shifted toward higher axial force amplitudes by increasing the plate width and decreasing the plate length. Alternatively, the axial force acting in the vicinity of a parametric combination frequency of the difference type shows a parametric antiresonance which is maximized by exactly the opposite tuning of the plate design. This guideline is important when plate design under the action of a harmonic axial force is considered. [ABSTRACT FROM AUTHOR]

Buton Asphalt is natural asphalt originating from Buton Island (Indonesia), with the potential deposit amount reaching up to 662 million tons. This substantial domestic mining potential must be utilized for domestic road needs and to boost the country's economy. However, Buton asphalt's utilization is minimal compared with imported oil asphalt, which reached a usage rate of up to 94 % in 2022. Therefore, as a form of a solution-oriented policy, Buton asphalt is included as one of the 21 commodities in the Strategic Roadmap for Downstream Investment in Indonesia, followed by various supportive regulations for developing this Buton asphalt product. One of the leading products the government targets is natural pure Buton asphalt. This product consists of >99 % bitumen content after extraction, also called Pure Buton Asphalt. The idea was to modify pure Buton asphalt with coconut coir to increase the Marshall Stability and Dynamic Stability values to make the asphalt mixture more resistant to vehicle loads and rutting. The tests were conducted to determine the optimum asphalt content (OAC) of the mixtures, Marshall's Stability comparison, and the dynamic stability test using a Wheel Tracking Machine to identify the comparison of permanent deformation. This study analyzed the Marshall characteristics and dynamic stability characteristics with variations in coconut coir content of 0.5 %, 0.75 %, and 1 % by weight of asphalt and variations in coconut coir length of 0.5 cm, 1 cm, and 1.5 cm. Based on the results of this study, the optimum asphalt content in this study is 6.76 %, where pure Buton Asphalt modified with coconut coir has an increase in Marshall's stability value and dynamic stability value compared to pure Buton asphalt without additional coconut coir [ABSTRACT FROM AUTHOR]

Fuel management is an important issue in aviation for safety and efficiency reasons. This work develops an alternative solution based on an artificial intelligent technique to the fuel distribution management problem in commercial aircrafts. The fuel flow control amongst tanks during the flight is addressed. A fuzzy management system is implemented that decides the best fuel distribution based on safety criteria (keeping engines fed) and dynamic stability (placing the centre of gravity at the appropriate position), amongst other specifications. Expert knowledge is used to define the rules of the fuel fuzzy control, taking into account that the dynamics of the system changes, whilst fuel is being consumed. It has been simulated on a real long‐range‐type commercial aircraft with satisfactory results regarding stability, even in the case of internal malfunction (in pipes, pumps, or valves), and with external disturbances (engine failure). The knowledge‐based fuzzy control is able to maintain the centre of gravity position within the stability and manoeuvrability margins along the flight. Besides, the intelligent control strategy minimizes the action of the actuators, providing some advantages to the control solution. [ABSTRACT FROM AUTHOR]

(1) Background: This study aimed to describe upper-limb (UL) movement quality parameters in women after breast cancer surgery and to explore their clinical relevance in relation to post-surgical pain and disability. (2) Methods: UL movement quality was assessed in 30 women before and 3 weeks after surgery for breast cancer. Via accelerometer data captured from a sensor located at the distal end of the forearm on the operated side, various movement quality parameters (local dynamic stability, movement predictability, movement smoothness, movement symmetry, and movement variability) were investigated while women performed a cyclic, weighted reaching task. At both test moments, the Quick Disabilities of the Arm, Shoulder, and Hand (Quick DASH) questionnaire was filled out to assess UL disability and pain severity. (3) Results: No significant differences in movement quality parameters were found between the pre-surgical and post-surgical time points. No significant correlations between post-operative UL disability or pain severity and movement quality were found. (4) Conclusions: From this study sample, no apparent clinically relevant movement quality parameters could be derived for a cyclic, weighted reaching task. This suggests that the search for an easy-to-use, quantitative analysis tool for UL qualitative functioning to be used in research and clinical practice should continue. [ABSTRACT FROM AUTHOR]

In this work, we are interested in studying bending, buckling stability, and dynamic behaviors of functionally graded nanobeams reinforced by carbon nanotubes (FG-CNTRC) by a novel shear deformation theory. This model is simple and efficient based on the new polynomial-exponential integral shear deformation theory including the effect of size taking into account the effects of the Winkler–Pasternak elastic foundations. The polynomial-exponential transverse shear function is incorporated to better represent a new displacement field that includes indeterminate integral terms. It is presumed that the material possessions of FG-CNTRC are diverse along the thickness direction employing distinct four distributions of carbon nanotubes (NT-CNTs). The nonlocal elasticity offered by Eringen is used to involve size effects in this approach. The impacts of numerous factors such as the volume fraction of CNTs, the nonlocality, and the impacts of the elastic foundation on the response of the FG-CNTRC beams are examined. [ABSTRACT FROM AUTHOR]

The existing methodologies employed for the quantification and regulation of tractor's tillage depth present considerable shortcomings, primarily characterized by their low accuracy and poor disturbance rejection proficiency in complex agricultural terrains. In this study, we present a sophisticated feedback control strategy designed to mitigate these challenges. Our innovative approach hinges on calculating tillage depth from the alignment of the tractor's hydraulic lifting arm, achieved by employing a mechanical angle sensor. This sensor adeptly gages the angle of the lifting arm, aligning it with the tillage angle of the pull rod and the implement's angle, resulting in a robust relational model correlating the lifting arm angle with the tillage depth. This pioneering method amalgamates the accuracy inherent in the static model, derived from the tillage angle-based depth measurement, with the dynamic stability afforded by the mechanical ascertainment of the lifting arm angle. In conjunction, we introduce a Hybrid Extended State Observer-Based Backstepping Sliding Mode Controller (HESO-BacksteppingSMC). The HESO is instrumental in estimating unmeasured state variables and lumped disturbances, utilizing the system's output feedback signal. Our control frame component capitalizes on the fast power-reaching law to yield a continuously smooth control signal, effectively eradicating the conventional chattering phenomenon inherent in controllers and amplifying its functional applicability. Theoretical evaluations affirm the uniformly and ultimately bounded stability of the errors associated with our proposed observer and controller, underscoring their robustness. The superior performance of our proposed tillage depth measurement and control methodology has been corroborated through a series of comprehensive simulation and field plowing trials, attesting to its precision and reliability in complex agricultural settings. [ABSTRACT FROM AUTHOR]

The Voronoi diagram on the Earth's surface is a significant data model, characterized by natural proximity and dynamic stability, which has emerged as one of the most promising solutions for global spatial dynamic management and analysis. However, traditional algorithms for generating spherical raster Voronoi diagrams find it challenging to dynamically adjust the Voronoi diagram while maintaining precision and efficiency. The efficient and accurate construction of the spherical Voronoi diagram has become one of the bottleneck issues limiting its further large-scale application. To this end, this paper proposes a dynamic construction scheme for the spherical Voronoi diagram based on the QTM (Quaternary Triangular Mesh) system, with the aim of enabling efficient generation, local updates, and multi-scale visualization of the spherical Voronoi diagrams. In this paper, canonical ordering is introduced. Tailored for the properties of the spherical triangular grid, it constructs a unified and standardized sorting strategy for the dilation of the spherical grids. The construction and updating of the spherical Voronoi diagram are achieved through the ordered dilation of sites. Furthermore, the multi-scale visualization of the spherical Voronoi diagram is realized through the hierarchical structure of the QTM. The paper presents our algorithm intuitively through pseudocode, conducts comparative experiments on the feasibility and efficiency, and designs an experiment for the dynamic navigation and management of ocean-going vessels based on the global multi-resolution Voronoi diagram. The experimental results demonstrate that our algorithm effectively controls the error of the generation of the raster Voronoi diagram and has a significant efficiency advantage when processing dynamic environments. [ABSTRACT FROM AUTHOR]

To date, the dynamic behavior of slopes in calcareous sand is unclear owing to the marine biological origin of calcareous sand. In this study, the internal deformation and the liquefaction mechanism of calcareous sand slopes were investigated by shaking table tests and numerical simulations. The influence of the presence of initial shear stress due to site inclination on the dynamic response of the slope was considered. Moreover, based on the microscopic particle properties of calcareous sand, the special dynamic response of the calcareous-sand slope during earthquakes was explored through the parallel test with the quartz sand field. The results reveal that calcareous-sand slopes exhibit higher dynamic stability during earthquakes than quartz-sand slopes, which is related to the larger occlusion caused by the irregular shapes and porosities of calcareous sand particles. However, the calcareous-sand slope still demonstrates a horizontal displacement of 0.32 times the slope height under strong earthquakes. Moreover, the settlement of the calcareous-sand slope suddenly increased 60 cm from the slope top, while that of the quartz-sand slope decreased with an increase in the distance from the slope top. The seismic protection strategies involving the use of quartz-sand slopes in the calcareous-sand slopes are inapplicable. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach for increasing the precision of high-precision positioning control experiments for a piezoelectric stick–slip actuator system. This is achieved through dynamic sliding mode control with a radial basis function neural network (RBFNN) based on the Lambert W function. The proposed control strategy is divided into two parts: scanning mode control and stepping mode control. For scanning control, a dynamic sliding mode controller was designed to solve the jitter problem in traditional sliding mode control. The introduction of the RBFNN avoids the effects of uncertainty terms and unknown disturbances in the model; reduces the controller gain, which must be adjusted; and improves the robustness of the system to disturbances. The stability of the dynamic sliding mode controller based on the RBFNN was verified through a Lyapunov analysis, and the Lambert W function was introduced to optimize the controller parameters responsible for the time lag in the closed-loop control system. This optimization improved the system's robustness against time delays, which can adversely affect its performance. Simulation and experimental results indicated that the proposed control strategy achieved a positioning control accuracy of <40 nm during the scanning phase and was robust in the presence of a load. In long-distance positioning control experiments, the control strategy achieved a control target of 40 μm while maintaining the positioning control accuracy and reducing the impact of time lag on the system. [ABSTRACT FROM AUTHOR]

Due to the Jacobian matrix rank reduction near singularities, applying numerical methods to study PMs' motion stability at singularities is quite difficult. As a result, there is a scarcity of literature on the investigation of PMs' dynamic behaviors near singularities and the influence of kinematic parameters on the motion stability of PMs. To address the research gap related to the above issues, based on the Gerschgorin perturbation method, Hurwitz exact approach, and the Lyapunov dynamic stability theory, the influence of kinematic parameters and external loads on a PM's motion stability at singularities is studied for the first time. The theoretical analysis results reported in this paper reveal many previously undiscovered features beyond those derived from previous numerical methods, and indicate the limitations of some widely accepted statements. For example, increasing the angular speed of the movable platform can expand the range of the external loads that meet the motion stability at singular configurations. The prevailing notion in prior research that PMs are unable to support external loads in the direction of the gained DoF at singular configurations is only partially accurate. This pioneering research establishes a theoretical foundation for exploring a new real-time approach to avoid dynamic singularities by fully exploiting the influence mechanisms of kinematic parameters on PMs' dynamic stability at singularities. [ABSTRACT FROM AUTHOR]

This study presents the results of the development and testing of a methodology for selecting parameters of the characteristics of fast valving in a steam turbine for emergency power system management to maintain dynamic stability based on machine learning algorithms. Modern power systems have reduced inertia and increased stochasticity due to the active integration of renewable energy sources. As a result, there is an increased likelihood of incorrect operation in traditional emergency automation devices, developed on the principles of deterministic analysis of transient processes. To date, it is possible to increase the adaptability and accuracy of emergency power system management through the application of machine learning algorithms. In this work, fast valving in a steam turbine was chosen as the considered device of emergency automation. To form the data sample, the IEEE39 mathematical model was used, for which benchmark laws of change in the position of the cutoff valve during the fast valving of a steam turbine were selected. The considered machine learning algorithms for classifying the law of change in the position of the steam turbine's cutoff valve, k-nearest neighbors, support vector machine, decision tree, random forest, and extreme gradient boosting were used. The results show that the highest accuracy corresponds to extreme gradient boosting. For the selected eXtreme Gradient Boosting algorithm, the classification accuracy on the training set was 98.17%, and on the test set it was 97.14%. The work also proposes a methodology for forming synthetic data for the use of machine learning algorithms for emergency management of power systems and suggests directions for further research. [ABSTRACT FROM AUTHOR]

The Wind Farms (WFs) are located far away from the load centres, with the resultant equivalent reactance being more than near the load. It results in a weak grid due to high power transferred in the transmission lines that affect the low frequency of oscillations, and the system exists with undamped functions. The transmission line has to be compensated to transmit wind power effectively. The Static Synchronous Series Compensator (SSSC) connects WF and the load centre. This work demonstrates a Power Oscillation Damper (POD) to WFs and SSSC for transmission lines and their combination. The eigenvalue of the damping ratio and frequency of oscillations are considered objective functions for particle swarm optimization and formulated based on stability to optimize the controller parameter for improving stability. The coordination between the POD and SSSC has been conducted using a Fuzzy Logic Controller (FLC) to further enhance system performance. The small signal and transient stability examinations use eigenvalue analysis and time-domain simulation. It is analysed by varying the length (km) of the transmission line between the WF and the load centre, along with variation in wind penetration. The study observed that small signal stability damped the oscillatory modes most effectively. It is also revealed that the controller's combination with FLC intensifies the capability under extreme disturbances and detects an improvement in the system's transient stability. The proposed approaches' effectiveness is evaluated on an IEEE-11 bus two-area test system with optimized controller gain parameters and controller coordinated FLC through a Real-Time Digital Simulator. [ABSTRACT FROM AUTHOR]

Introduction: Perturbation-based balance training (PBT) is promising for fall prevention in older adults, mimicking real-life fall situations at a person's stability thresholds to improve reactive balance. Hence, it can be associated with anxiety, but knowledge about the acceptability of PBT is scarce. Method: This is a secondary analysis of a randomized controlled trial comparing the effects of two different PBT paradigms that aims to evaluate and compare the acceptability of those training paradigms in fall-prone older adults. Participants (74.9 ± 5.7 years) who completed the training (6 weeks, 3x/week) on either a perturbation treadmill (PBTtreadmill: n = 22) or unstable surfaces in the presence of perturbations (PBTstability: n = 27) were surveyed on the acceptability of PBT using a 21-item questionnaire addressing seven domains (perceived effectiveness, tailoring, demand, safety, burden, devices, affective attitude), based on the theoretical framework of acceptability and context-specific factors. Relative scores (% of absolute maximum) for single items and domains were calculated. Results: Median domain scores of perceived effectiveness, tailoring, safety, devices, and affective attitude were all ≥70% for both paradigms. The highest scores were obtained for tailoring (both paradigms = 100% [interquartile range 80–100%]). Domain scores of demand and burden were in the medium range (40–45%) for both paradigms. No significant differences between paradigms were found for any domain score. Two single items of safety differed significantly, with PBTtreadmill perceived as needing less support (p = 0.015) and leading less often to balance loss (p = 0.026) than PBTstability. Conclusion: PBT conducted on a perturbation treadmill or unstable surfaces is well accepted in this fall-prone older sample, even though it is conducted at individual stability thresholds. Tailoring may play a key role in achieving high levels of perceived effectiveness, appropriate levels of demand and burden, and a high sense of safety. PBT delivered on treadmills might be more appropriate for more anxious persons. [ABSTRACT FROM AUTHOR]

This study employs a first-principles approach to comprehensively examine the structural, electronic, optical, and magnetic properties of the thermodynamically stable scintillating double perovskite halides A 2 N a T a X 6 ( A = C s , R b ; X = C l , B r , I ). The dynamic stability of these materials were explained based on deduced phonon properties. Our analysis reveals that these compounds exhibit intriguing electronic behavior with spin polarization, demonstrating half-metallicity. In spin-up, the band gap is found to be zero, while in spin-down, it falls within the range of 3 to 4 eV with the incorporation of DFT+U corrections. Notably, the optical properties assessment highlights the exceptional UV and high-energy absorption capabilities of A 2 N a T a I 6 , making it a promising candidate for scintillation applications in particle detection. This research sheds light on the unique and versatile properties of these materials, with implications for various technological and scientific applications. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effects of TRX suspension applications on lower body muscle strength and balance skills in sedentary individuals. Materials and Methods: The study included 60 sedentary individuals aged 30-45 years. The participants were divided into 2 groups as Suspension Strength Group (SSG) and Traditional Strength Group (TSG). SSG performed 45 minutes of exercise for a total of 8 weeks, 2 days a week. The TSG group applied for an 8-week, 45-minute basic strength program for a total of 2 days a week. Anthropometric measurements, grip strength, push-up, squat, sit-up, plank and balance tests were taken before and after the 8-week exercise protocol. Results: In this study, which was conducted to determine the effects of TRX movements on strength and balance skills in sedentary individuals, significant differences were found in SSG as opposed to TSG as a result of the data in this study conducted to determine the effects of suspension exercises on muscle strength development in individuals. As a result of the exercise protocol lasting 8 weeks in total; improvement was found in all data of SSG and in certain parameters of TSG. According to the last measurements, there was a difference in push-up, squat, sit-up and plank performances. Conclusion: it was found that strength training on moving surfaces showed more improvement than traditional strength training. In addition, it is thought that suspension exercises may be a new alternative training model for strength development. [ABSTRACT FROM AUTHOR]

In this work, an in-depth investigation into enhancing quadcopter autonomy and control capabilities is presented. The focus lies on the development and implementation of three conventional control strategies to regulate the behavior of quadcopter UAVs: a proportional–integral–derivative (PID) controller, a sliding mode controller, and a fractional-order PID (FOPID) controller. Utilizing careful adjustments and fine-tuning, each control strategy is customized to attain the desired dynamic response and stability during quadcopter flight. Additionally, an approach called Dyna-Q learning for obstacle avoidance is introduced and seamlessly integrated into the control system. Leveraging MATLAB as a powerful tool, the quadcopter is empowered to autonomously navigate complex environments, adeptly avoiding obstacles through real-time learning and decision-making processes. Extensive simulation experiments and evaluations, conducted in MATLAB 2018a, precisely compare the performance of the different control strategies, including the Dyna-Q learning-based obstacle avoidance technique. This comprehensive analysis allows us to understand the strengths and limitations of each approach, guiding the selection of the most effective control strategy for specific application scenarios. Overall, this research presents valuable insights and solutions for optimizing flight stability and enabling secure and efficient operations in diverse real-world scenarios. [ABSTRACT FROM AUTHOR]

In this study, natural rubber (NR)/polybutadiene rubber (PB) blend-based composites were prepared using graphene as a partial replacement for carbon black (CB) in different parts per hundred rubber (phr) percentages. In a previous study, the vulcanization characteristics, viscoelastic behavior, and static mechanical properties were reported, and the compound labeled as compound 2 (with 2.5 phr of graphene and 52.5 phr of carbon black) showed optimum properties. Herein, we report the dynamic mechanical properties and the transport properties of the formulations to establish further characterization of the compounds. Three different organic solvents comprising benzene, toluene, and xylene were employed to analyze the sorption characteristics. The obtained data were also modeled with different theoretical predictions. The dynamic mechanical properties showed that certain compounds can be considered to be green tire formulations, as there were appreciable changes in the tanδ values at different temperatures (−25 °C to 60 °C). The thermogravimetric analysis showed that compound 2, with 2.5 phr of graphene, has a higher t50 value among the studied formulations, which indicates higher thermal stability than the base compound. The partial replacement of 2.5 phr of graphene in place of carbon black (total 55 phr) led to appreciable improvements in terms of thermal stability, transport properties, and dynamic mechanical properties. [ABSTRACT FROM AUTHOR]

Knowledge is limited regarding how neuromuscular training, conducted before and after soccer training, affects the fitness levels of youth soccer players. In this study, we aimed to analyze the effects of an eight-week neuromuscular training (NMT) program implemented before or after a soccer session on physical fitness in youth soccer players. Thirty-two youth soccer players were categorized into two groups—namely, NMT before soccer-specific training (NBS; n = 15) and NMT after soccer-specific training (NAS; n = 17). NMT comprised integrated resistance, dynamic stability, core, and plyometric training three times weekly and was conducted for 8 weeks. Before and after the exercise intervention, the counter-movement jump (CMJ) and 10 and 20 m sprint were analyzed, and the results of the T-agility test, Illinois change of direction test (ICDT), and Y-balance test were assessed for all participants. In terms of the interaction between the effects of the time of observation and group, both groups showed improvement in the results of the 10 m sprint and T-agility and Y-balance tests. Regarding the difference in the time of observation, the NBS group showed positive improvements in the results of the CMJ, 10 and 20 m sprints, and T-agility test after the exercise intervention, and the NAS group showed positive improvements in the results of the CMJ, 10 m sprint, T-agility test, and ICDT after the exercise intervention. These findings suggest that neuromuscular training has the potential to improve the 10 m sprint ability and T-agility test results of youth soccer players, regardless of the training sequence. [ABSTRACT FROM AUTHOR]

To accurately assess the dynamic stability of the damaged ship, this paper performs an experimental campaign and presents a feasible numerical method to analyze the effects of microscopic air–fluid interactions on the motion responses of the damaged ship. The numerical approach can be applied to solve the coupled hydrodynamic behavior between the flooding process and the motion responses of the damaged ship. The volume of fluid (VOF) method was applied to capture the interface of the free surface, while the dynamic fluid–body Interaction (DFBI) morphing technique was applied to deal with mesh adaption. In particular, the UDF (user-defined field) function was activated to realize the initial distribution of the free surface. Firstly, by comparing the experimental and numerical results, the reliability of visualizing the flooding process and dealing with the motion responses of the damaged ship was efficiently verified. The numerical flooding process was able to reproduce the hydrodynamic phenomenon well, including the flooding jet, interaction, and flow between adjacent compartments. The numerical roll motion curve of the damaged ship was consistent with that predicted in the model test, with an error in roll amplitude of no more than 4%. Secondly, based on the verified numerical method, it was seen from the results with different ventilation positions that not only the air compressibility due to varying levels of ventilation cannot be neglected in damage assessment, but also the position of the ventilation hole was crucial. This was because different positions will create different paths for the compressed air to overflow and affect air–fluid interactions. Thus, the flooding force and air-impacting force acting on the internal hull will be different. In conclusion, this paper introduces a new consideration in the damage assessment of ships. [ABSTRACT FROM AUTHOR]

The stability performance of the buoy is an important parameter that should be taken into account when designing marine buoys. This paper introduces a theoretical and numerical analysis method to examine the stability of marine buoys, including analysis of the initial stability and large inclination stability by calculating the natural period, metacentric height, static stability, and dynamic stability, deriving the calculation process of the static stability lever in detail to obtain the righting moment, and so on, showing that the designed buoy in this paper has sufficient stability performance with theoretically excellent resistance performance to the wind and waves. Additionally, the hydrodynamic performance of the buoy at different heights is also further analyzed for structural optimization, which concluded that the buoy would have a more balanced stability performance when the buoy's width-to-height ratio is 0.375–0.5, hoping that the computational model and ideas used in this paper can provide a reference for the theoretical stability analysis and buoy design of other types of buoys. [ABSTRACT FROM AUTHOR]

The cable-stiffened single-layer latticed shell is an innovative structural design that achieves a perfect balance between lightweight and stability by combining cables and a latticed shell. However, the study on dynamic response and failure mechanism of cable-stiffened single-layer latticed shell under seismic action is still lacking. Therefore, small-scale shaking table tests of two kinds of single-layer spherical latticed shells are carried out; the dynamic response and failure mode of the two shells under sine wave earthquake are investigated by using time history analysis. The conclusions show that the introduction of the prestressed cable plays an important role in improving the seismic performance of the single-layer latticed shell, and the cable-stiffened single-layer latticed shell has better load capacity and seismic performance under earthquake action than the ordinary single-layer latticed shell structure. [ABSTRACT FROM AUTHOR]

This study aims to provide a brief overview of the novel Coronavirus (COVID-19), which has spread to nearly 200 countries and regions worldwide but is still active. We are particularly concerned by the COVID- 19 economic perspective, which presents an Asian perspective challenge. The COVID-19 scenario is continually unfolding, and this research draws on evidence from published studies and news outlets. To delve deeper into the subject, we categorize the economic impact into four groups: Central and West Asian countries, East Asian countries, South Asian countries, and Southeast Asian. The consequences are dire: lower exports, slowed international economic activity, lower inward demand, and lower local consumption. However, by addressing key challenges based on New Structural Economics (NSE) and employing the market's comparative advantage strategy, Asian economies can be well-positioned to pursue stable and efficient economic development. The primary goal of the examination is to determine the factor endowment and structure. Furthermore, we advocate for a facilitating state because its functions enable structural change through operating industrial strategy to mitigate market breakdowns and support industries by concealing comparative advantages in the market to achieve stability and dynamic development. As a result, Asian economies must embark on a path to state-friendly and market-driven development following COVID-19. COVID-19 has negatively impacted economies, especially in emerging nations. As a result, Asian economies must urgently implement measures that encourage both government intervention and good market practices in order to stimulate economic progress. This includes promoting structural transformation through industrial strategy, addressing market failures, and assisting industries in achieving market stability and encouraging dynamic growth by using their comparative advantages. [ABSTRACT FROM AUTHOR]

ObjectiveTo investigate the neuromuscular activity characteristics of Tai Chi athletes and identify optimal muscle synergy patterns.MethodData were collected from 12 elite Tai Chi athletes using a Vicon motion capture system, a Kistler 3D force plate, and a Noraxon surface electromyography system. Muscle synergy patterns were extracted using Non-negative Matrix Factorization.ResultsFour muscle synergy patterns were identified in each of the three phases of the leg stirrup movement, with the optimal synergy pattern for each phase determined as follows: knee lift phase: rectus femoris and vastus lateralis of the right leg; extension phase: rectus femoris, vastus lateralis, biceps femoris, and medial gastrocnemius of the right leg; recovery phase: rectus femoris, vastus lateralis, and medial gastrocnemius of the right leg. These patterns explain the muscle coordination activities for each phase.ConclusionThis study identified the optimal muscle synergy patterns for each phase, supporting the fluidity and force generation of the leg stirrup movement. This provides Tai Chi athletes with a more efficient way to exert strength and maintain balance.

Low-frequency oscillations (LFO) are generated in interconnected electric networks because of the weak tie lines between the parts of the networks. Such oscillations have been a significant challenge for engineers that may lead to system instability if appropriate measures are not taken. This article proposes two new metaheuristic algorithms, the jellyfish search algorithm (JSA) and the tunicate swarm algorithm (TSA), to design the power system stabilizers (PSS) for single machine infinite bus (SMIB) and multimachine power system (MPS) networks. The proposed method uses the JSA and TSA to dampen out the LFOs by modifying the vital parameters of lead-lag type conventional PSS (CPSS). A damping ratio-based objective function improves both models' system damping. These methods are tested on an SMIB system and two distinct MPS networks exposed to the three-phase fault under various loading conditions. The effectiveness of the suggested approach has been studied by comparing the system eigenvalues and minimum damping ratio (MDR) produced from JSA and TSA-tuned PSS and the CPSS. In addition, time domain simulation results are compared, demonstrating that the new approach outperforms the standard techniques, such as particle swarm optimization (PSO) and backtracking search algorithm (BSA). In the SMIB system, MDR produced by JSA and TSA-based PSS is 2.55 times higher than that of CPSS. Similarly, in comparison to PSO and BSA-based PSS, JSA, and TSA-tuned PSS offer >1.4 times greater MDR in the Two Area Four Machine network and up to 8.4 times larger MDR for the IEEE-39 Bus network. Furthermore, the efficacy of the suggested JSA and TSA approaches' prediction capacity is validated by satisfying the values of statistical performance metrics.

Pipeline transport is proven to be an efficient method for conveying fluids over long distances, offering benefits such as continuous transport, significant volume capacity, lower energy costs, and substantial environmental advantages. Damage to pipelines could have detrimental effects on the economy, the environment, and pose health and safety risks for the population. The safety issues associated with pipes garner considerable attention in both scientific research and industry. The focus of the current study is on the dynamic stability of a straight fluid-conveying pipe with an elastic support. The investigation is based on the Euler-beam model and involves the use of Laplace and Fourier transformations. The paper draws attention to the stability of inclined pipes, as they haven’t received much attention.

The study analyzed the influence of periodic and aperiodic stiffness distribution for the four-element Bernoulli-Euler beam on the first two eigenfrequencies and the dynamic stability of the system. The influence of increasing the ratio of cross-sections of the analyzed elements was also analyzed. Significant differences were found in eigenfrequencies and dynamic stability. Using the variational Hamilton principle, the equation of motion was derived, on the basis of which the values of the eigenfrequencies were determined, and the transformation into the form of the Mathieu equation made it possible to determine the dynamic stability for the analyzed structures.

Abstract Resilience has increasingly become a crucial topic to the function of various real-world systems as our planet undergoes a rising trend of uncertainty and change due to natural, human and technological causes. Despite its ubiquitous use, the term resilience is poorly and often inconsistently used in various disciplines, hindering its universal understanding and application. This study applies the resilience system interpretation framework, which defines resilience irrespective of its disciplinary association, in the form of adaptation and adaptive systems, to two traffic flow systems. The system framework defines resilience as the ability of the system state and form to return to their initial or other suitable state or form through passive and active feedback structures. Both components of the system framework are demonstrated through practical simulation scenarios on the modified viscous Burgers’ equation and the LWR-Greenshields model equipped with an adaptive Extremum seeking control, respectively. This novel and systematic understanding of resilience will advance resilience analysis, design, and measurement processes in various real-world systems in a unified fashion and subsequently pave the way for resilience operationalization and its integration into industry standards.

Abstract Background Dynamic stability is a fundamental goal in standing activities. In this regard, monitoring, analysis, and interventions made to improve stability is a research topic investigated in the biomechanics of human movements. Vision has a major role to play in controlling human movement. Nonetheless, little is known about the effects of visual deprivation, especially from birth on dynamic gait stability. Methods The current study was conducted on 20 congenital blind and 10 sighted people (15–38 years). To evaluate the dynamic stability, descriptive data, harmonic ratio (HR), improved harmonic ratio (iHR), and root mean square (RMS), based on trunk acceleration data were measured in three axes: anteroposterior (AP), vertical (V), and mediolateral (ML) while participants walked an eight-meter straight path. Results In the comparison of blind and sighted people (eyes open), standard deviation, HR, iHR, and RMS indices were found to be significantly different in both AP and V directions. All the mentioned parameters were significantly lower in blind than in sighted participants. In the comparison of blind people and sighted ones with closed eyes, changes were observed in the maximum, range, standard deviation, and RMS only in the AP axis. In the comparison between eyes open and closed in sighted people, a significant difference was found only in the harmonic ratio of the vertical axis. Conclusion Visual deprivation led to a decrease in dynamic stability parameters in the AP and V axes. Even the movement of sighted people in unchallenged conditions is dependent on visual information.

Abstract Human locomotion is controlled by spinal neuronal networks of similar properties, function, and organization to those described in animals. Transspinal stimulation affects the spinal locomotor networks and is used to improve standing and walking ability in paralyzed people. However, the function of locomotor centers during transspinal stimulation at different frequencies and intensities is not known. Here, we document the 3D joint kinematics and spatiotemporal gait characteristics during transspinal stimulation at 15, 30, and 50 Hz at sub-threshold and supra-threshold stimulation intensities. We document the temporal structure of gait patterns, dynamic stability of joint movements over stride-to-stride fluctuations, and limb coordination during walking at a self-selected speed in healthy subjects. We found that transspinal stimulation (1) affects the kinematics of the hip, knee, and ankle joints, (2) promotes a more stable coordination at the left ankle, (3) affects interlimb coordination of the thighs, and (4) intralimb coordination between thigh and foot, (5) promotes greater dynamic stability of the hips, (6) increases the persistence of fluctuations in step length variability, and lastly (7) affects mechanical walking stability. These results support that transspinal stimulation is an important neuromodulatory strategy that directly affects gait symmetry and dynamic stability. The conservation of main effects at different frequencies and intensities calls for systematic investigation of stimulation protocols for clinical applications.

The Southern Cameroon Interconnected Network (SIG) is depicted as a large-scale power system that has shown significant instability due to a series of blackouts in recent years. These blackouts are primarily attributed to major disruptions in transmission lines and energy deficits between supply and demand. The imbalance between power supply and demand necessitates the grid to operate near its stability limits, increasing the risk of blackouts. The necessity of investigating the dynamics of SIG behavior in response to observed contingency situations serves as the primary motivation for this study. To achieve this objective, the SIG was modeled using saturated generators with ZIP static loads. Through Newton-Raphson based power flow calculations, voltage magnitude profiles of the grid were obtained for each generation scenario. An N-1 contingency consisting of a standard Newton-based continuation power flow (CPF) analysis has identified line 5–6 as the most frequent worst case of line outage. Additionally, a short-term transient analysis was conducted under three-phase short-circuit, line outage and generator outage scenarios. In the event of a short-circuit, the Mangombe-225 bus experienced the most significant impact. Concerning line outages, line 1–5 had the most adverse effect on the grid's frequency stability. However, generation outages had a lesser impact on frequency stability compared to other disturbances. Lastly, modal analysis revealed that the grid exhibited weak stability with a critical mode identified at a frequency of 4.0267 Hz, exceeding typical values. This underscores the necessity of damping the grid oscillations for enhanced stability.

This study discusses the feasibility of diversifying the scope of application of lead-free Sr3ZBr3 (Z = As, Sb) as promising materials for their enhanced electronic, mechanical, optical, thermodynamic, and thermoelectric properties using first-principles calculation based on Density Functional Theory (DFT). Both compounds have cubic crystal structures, and both materials' dynamic stability is validated by the lack of negative frequencies in their phonon dispersion spectra. Besides ground state physical characteristics, we also examined the impact of hydrostatic pressure (0–21 GPa) on electronic, mechanical, and optical properties. The lattice parameters exhibit a linear decrease from 6.27 to 5.61 Å for Sr3AsBr3 and 6.45 to 5.71 Å for Sr3SbBr3 under increasing pressure, attributed to bond length reduction, which alters their physical properties. Initially observed direct band gap (Γ-Γ) of Sr3AsBr3 and Sr3SbBr3 were 2.35 and 2.30 eV using modified Becke-Johnson (mBJ) functional which reduces to 1.15 and 0.82 eV as the compounds go from 0 to 21 GPa pressure. This study reveals enhanced optical properties under pressure, with broader spectral response, increased sensitivity, and improved dielectric constant. Optical absorption and conductivity also shift toward lower-energy photons. The investigation further shows that the compounds show brittle to ductile transition under high pressure. Their ductility and anisotropy nature are further enhanced with pressure along with other mechanical features. The thermodynamic properties indicate their ability to withstand and perform well at high temperatures and pressures. Lastly, the thermoelectric properties of Sr3ZBr3 (Z = As, Sb) were assessed through electrical and thermal conductivity, Seebeck coefficient, power factor (PF), and figure of merit (ZT) as a function of temperature. Both compounds exhibit high PF and near-unity ZT. These findings underscore their potential as strong candidates for optoelectronic and thermoelectric devices, owing to their direct bandgap and exceptional properties.