Search

We study the natural action of S n on the set of k-subsets of the set { 1 , … , n } when 1 ≤ k ≤ n 2 . For this action we calculate the maximum size of a minimal base, the height and the maximum length of an irredundant base. Here a base is a set with trivial pointwise stabilizer, the height is the maximum size of a subset with the property that its pointwise stabilizer is not equal to the pointwise stabilizer of any proper subset, and an irredundant base can be thought of as a chain of (pointwise) set-stabilizers for which all containments are proper.

Heterogeneous drone swarms are large hybrid drone clusters in which multiple drones with different wireless protocols are interconnected by some translator drones called GWs. Nowadays, because inexpensive drones, such as toy drones, have become widely used in society, the technology for constructing huge drone swarms is attracting more and more attention. In this paper, we propose an autonomous GW mobility control algorithm for establishing stabilized and low-delay communication among heterogeneous clusters, assuming that only GWs are controllable and relocatable to ensure the flexible operationality of drone swarms. Our proposed algorithm is composed of two independent sub algorithms - the Link Stabilizer and the Path Optimizer. The Stabilizer maintains the neighbor links and consists of two schemes: the neighbor clustering based on relative velocities and the GW velocity calculation using a kinetic model. The Optimizer creates a shortcut to reduce the end-to-end delay for newly established communication by relocating the GW dynamically. We also propose a conceptual protocol design to implement this algorithm into real-world drone swarms in a distributed manner. Computer simulation reveals that the Stabilizer improved the connection stability for all three mobility models even under the high node mobility, and the Optimizer reduced the communication delay by the optimal shortcut formation under any conditions of the experiments and its performance is comparable to the performance upper limit obtained by the brute-force searching.

Мета роботи: дослідження змін електроміографічної активності м’язів, що забезпечують стабільність крижово-клубових суглобів під час утримування вертикального осьового положення при одно- та двохопорному стоянні з вантажем та без нього при різних показниках фронтального хребтово-тазового балансу. Матеріали та методи. Було досліджено 36 практично здорових волонтерів — студентів факультету фізичної культури. У групу дослідження ввійшли 25 юнаків та 11 дівчат. Середній ріст волонтерів становив 173 см (від 168 до 183 см), середній індекс маси тіла — 2,99 (від 2,62 до 3,34). Проводили електроміографічне дослідження м’язів, підтримуючих стабільність крижово-клубових суглобів при двохопорному, одноопорному стоянні («тест лелеки»), одноопорному стоянні з вантажем 5 кг у контрлатеральній руці. Волонтер приймав необхідне положення тіла та утримував його протягом 10–15 с. Протягом цього часу записували білатерально на m. erector spinae біоелектричну активність. Використовували поверхневі електроди Skintact RT-34. Аналізували такі показники електроміо-графії: максимальну амплітуду, середню амплітуду, сумарну амплітуду та середню частоту при фільтрації частот нижче 20 Гц. Усім волонтерам робили рентгенографію таза стоячи із захватом обох кульшових суглобів. Результати. Нахил крижі та таза призводить до асиметричної активності m. erector spinae, що підвищується із збільшенням кута їх нахилу. При одноопорному стоянні за відсутності нахилу крижі та таза було відмічено підвищення активності m. erector spinae на стороні опорної кінцівки, однак збільшення кута нахилу таза в сторону опорної кінцівки призводить до збільшення активності m. erector spinae на стороні піднятої кінцівки. При посиленому варіанті виконання тесту (стоянні на одній нозі з вантажем) була виявлена більша різниця між активністю цього м’яза на стороні опорної кінцівки і активністю — піднятої кінцівки. При опорі на нижню кінцівку на стороні, протилежній нахилу, була відмічена підвищена активність m. erector spinae на опорній стороні.

The prime objective of the proposed work is to create a method for solar power stabilizer under deregulated environment. A robust thermal power system was designed and implemented in the present work. In this an advancement procedure enhanced Artificial Bee Colony (ABC) algorithm was investigated to settle the recurrence and tie-line power motions successfully. The robust solar power system stabilizer (RPSS) was planned to utilize the upgraded ABC for the planning of regulators for dynamical frameworks for electrical designing. The main objectives of this research are to reduce the oscillation and to increase the overall robust performance of the system. The proposed technique adopts the stability margin (e) as the index of robustness and performance of the controlled system. As an outcome a correlation were made between the conventional force framework stabilizer (CFFS) and PSS with H∞ improvement as an additional source. An improvement was seen in the ABC in contrast with different methods that leads to produce an efficient result and to generate the desired response.

The basic aim of the power system stabilizer is to damp the fluctuations that occur on the rotating axis of the synchronous generator that result from noise or disturbance on the power system. This is achieved by producing an appropriate damping torque for these fluctuations across the excitation circuit of the generator and for a wide range of operation conditions. The study describes the types of power system stabilizers and giving an mathematical model of the power system that consists of a synchronous machine connected to the infinite bus though transmission lines. This has been achieved by simulating the electric and mechanical equations of power systems and proposing a methodological approach to design a Fuzzy Logic Power System Stabilize (FPSS) relaying in the design on the (Matlab/Fuzzy logic toolbox).Speed deviation (Δω) and acceleration (∆ ) of the synchronous machine are chosen as the input signals to the fuzzy controller in order to achieve a good dynamic performance .The complete range for the variation of each of the two controller inputs is represented by a 7×7 decision table, i.e. 49 rules using proportional derivative like fuzzy logic. The power system (SMIB) was tested with the presence and absence of the excitation system, then (CPSS) was added, and then (FPSS).The simulation results of the proposed fuzzy logic on )SMIB( gave a better dynamic response, decreased the settling time and good performance of the stabilizer in damping the fluctuations that arise in the speed of rotation of the generator and its active power in various operating conditions when proposed (FPSS) is compared with conventional PSS. The simulation results proved the superior performance of the proposed (FPSS).

Objective Neuroendovascular procedures rely on successful navigation and stable access to the target vessel. The Stabilizer is a 300 cm long exchange wire with a 0.014 diameter and a soft, flexible stent at the distal end designed to assist with navigation and device delivery. This study aims to assess the efficacy of the Stabilizer for navigation in a variety of challenging environments. Methods The efficacy of the Stabilizer was evaluated using three challenging vascular models: a giant aneurysm model, a severe tortuosity model, and an M1 stenosis model. The Stabilizer was compared with a conventional wire during navigation in each model. Results In the giant aneurysm model, there was no significant difference of success during straightening of a looped wire and significantly higher success rates when advancing an intermediate catheter with the Stabilizer beyond the aneurysm neck compared to a conventional guidewire. The Stabilizer also significantly increased success rates when advancing an intermediate catheter through a model with severe tortuosity compared to a conventional guidewire, as well as exchange maneuver for intracranial stenting in a stenosis model compared to an exchange wire. Conclusions In our experimental model, the Stabilizer significantly improved navigation and device delivery in a variety of challenging settings compared to conventional wires.

In this paper, a modified technique based on the combination of the Single Neuron PID (SNPID), as the main controller and Sliding Mode Control (SMC), as an adaptation technique, to design an optimized self-tuned for SNPID controller that may overcome difficulties faced when a change in system operating points occurs. The proposed approach has been implemented as a power system stabilizer (PSS) for a synchronous generator connected to an infinite bus. The Flower Pollination (FP) optimization is based on an appropriate objective function. To demonstrate the effectiveness of the combination obtained controllers, PSS, is tested under different operating conditions. The combination controllers are shown through uncertainties system parameters changes under different disturbances. The results show the ability of the suggested controllers to enhance well the system performances

This article presents a robust stabilizer designed to damp low-frequency electromechanical oscillations which occurs in induction machines controlled by scalar control when operating at low speed and light load. The robust stabilizer design is based on the linear parameter varying (LPV) approach. A discrete LPV model is identified to allow the design of the robust LPV controller. Experimental tests are performed on a 7.5-kW induction motor dynamometer using an industrial inverter driver. The results show satisfactory improvement of the motor performance with the damping controller activated.

Purpose The extensive increase in power demand has challenged the ability of power systems to deal with small-signal oscillations such as inter-area oscillations, which occur under unseen operating conditions. A wide-area measurement system with a phasor measurement unit (PMU) in the power network enhances the observability of the power grid under a wide range of operating conditions. This paper aims to propose a wide-area power system stabilizer (WAPSS) based on Gaussian quantum particle swarm optimization (GQPSO) using the wide-area signals from a PMU to handle the inter-area oscillations in the system with a higher degree of controllability. Design/methodology/approach In the design of the wide-area stabilizer, a dead band is introduced to mitigate the influence of ambient signal frequency fluctuations. The location and the input signal of the wide-area stabilizer are selected using the participation factor and controllability index calculations. An improved particle swarm optimization (PSO) technique, namely, GQPSO, is used to optimize the variables of the WAPSS to move the unstable inter-area modes to a stable region in the s-plane, thereby improving the overall system stability. Findings The proposed GQPSO-based WAPSS is compared with the PSO-based WAPSS, genetic algorithm-based WAPSS and power system stabilizer. Eigenvalue analysis, time-domain simulation responses and performance index analysis are used to assess performance. The various evaluation techniques show that GQPSO WAPSS has a consistently good performance, with a higher damping ratio, faster convergence with fewer oscillations and a minimum error in the performance index analysis, indicating a more stable system with effective oscillation damping. Originality/value This paper proposes an optimally tuned design for the WAPSS with a wide-area input along with a dead-band structure for damping the inter-area oscillations. Tie line power is used as the input to the WAPSS and optimal tuning of the WAPSS is performed using an improved PSO algorithm, known as Gaussian quantum PSO.

Real stabilizer operators, which are also known as real Clifford operators, are generated, through composition and tensor product, by the Hadamard gate, the Pauli Z gate, and the controlled-Z gate. We introduce a normal form for real stabilizer circuits and show that every real stabilizer operator admits a unique normal form. Moreover, we give a finite set of relations that suffice to rewrite any real stabilizer circuit to its normal form., In Proceedings QPL 2021, arXiv:2109.04886

High-voltage direct current breaker is among the essential components of high-voltage direct current grids. Such a breaker generally needs a direct current reactor to reduce the fault currents rate. However, direct current reactors have destructive effects on the multi terminal high-voltage direct current grid dynamic stability, and in such a system, despite the variety of controllers, the system dynamics are highly sensitive to the operating point. Therefore, additional damping control will be needed. This paper proposes a modification to be applied to the traditional droop controller of high-voltage direct current grids to cope with the influence of these large reactors, improving the direct voltage stability and decreas ing power variations in the transient events by introducing a direct current power system stabilizer. The proposed method for direct voltage control has been investigated through the analytical model of the system. Stability improvement has been studied following the application of the proposed method by investigating zeros, poles, and frequency response analysis. Moreover, a method is proposed for optimal design and optimal placement of direct current power system stabilizer. The system analysis and time-domain simulations demonstrate a decent damping improvement attained by the proposed method. All simu lations and analytical studies are conducted on Cigré DCS3 test high-voltage direct current grid in MATLAB/Simulink

This paper focuses on autonomous underwater vehicle (AUV) stabilization in the nonlinear descriptor model, as well as some AUV limitations such as model uncertainty, singularity, saturation constraint, and time delay. The capability of the descriptor model to show the real model is more reasonable than the standard state-space model. Based on the constructed Lyapunov function method and applying the bilinear matrix inequalities technique, all of the constraints are handled by introducing the new theorem. This theorem aims to design a state feedback with the intent that the closed-loop system be admissible. Here, the results are less conservative than other approaches. This issue has not yet been fully addressed in the literature, especially on AUVs. Theorem achievement is implemented on new AUV descriptor model that is obtained and introduced here. This method covers both neutral and descriptor systems. Also, it can be generalized and applied to conventional AUVs or similar dynamics. Examples and simulation results illustrate the effectiveness of the proposed approach.

Management of varus posteromedial rotatory instability (VPMRI) of the elbow presents a challenging problem, sometimes requiring supplemental external fixation or ulnohumeral cross-pinning. A relatively new treatment adjunct for posterolateral rotatory instability of the elbow has become available with the development of the internal joint stabilizer (IJS) implant. However, this has not been studied for VPMRI because the implant is thought to be ineffective at treating this instability when placed in the usual manner on the lateral side of the elbow. We hypothesize that modifying the IJS technique to place the implant medially will make it as effective as external fixation at preventing VPMRI.Nine whole-arm cadaveric specimens were tested on a rig that allowed for gravity stress of the elbow at 60° of abduction. Intact specimens (INT) were tested to find the baseline stability with all structures intact. Then, O'Driscoll type 2-subtype III coronoid fractures were created with a microsagittal saw, and these same specimens were again tested without any fixation (WAF), with a static lateral external fixator (SLEF), and with a medially placed IJS (MIJS). The method for medial IJS placement is detailed within.The WAF specimens were significantly more unstable than the INT, SLEF, and MIJS groups (P.001). There was no difference in stability between the INT and the SLEF (P = .59) or MIJS group (P = .21).In this cadaveric model, a medially placed IJS was as effective as an SLEF at maintaining elbow stability in a coronoid-deficient elbow. This technique allows for early elbow range of motion, with no external hardware, and may eliminate the complications associated with external fixation or ulnohumeral cross-pinning.

This article presents an advanced parameter-free velocity observer-based nonlinear decentralized tension control scheme for roll-to-roll systems governed by nonlinear dynamics. The system parameter uncertainties and nonlinear dynamics yield the second-order perturbed nominal open-loop systems, which are used for devising the web velocity and tension control law for each station. The features of this result are summarized as follows: (a) the tension-derivative observers including the disturbance observer mechanism as a subsystem, (b) the observer-based active-damping pole–zero cancellation velocity error stabilizer for each tension loop, and (c) the closed-form nonlinear feedback gain boosters and exponential surface stabilizers to secure the improved transient performance and robustness for web velocity and each tension loop. The various simulation results based on MATLAB/Simulink show both the qualitative and quantitative advantages of the proposed technique.

This article investigates an enhanced optimal robust time-delay stabilizer for an autonomous underwater vehicle in the descriptor model. Time-delay, model uncertainty, and actuator saturation constraint are some practical challenges in autonomous underwater vehicle controller design. In this regard, an appropriate autonomous underwater vehicle descriptor model is obtained, and sufficient stabilization conditions are determined in the terms of linear matrix inequality. The obtained criterion guarantees the system to be regular, impulse-free, and stable. Meanwhile, the delay-dependent and rate-dependent conditions are taken into account. Furthermore, uncertainty and time-delay are time-variant. This method includes a tuning factor for practical design aspects and tradeoff among desired requirements. Also, as an essential general requirement in non-linear systems, the maximal estimate of the attraction domain is proposed as an optimization problem. Numerical examples and simulations illustrate that the proposed methods are effective and useful in less conservative results. The technique can be generalized and applied to the most conventional autonomous underwater vehicles.

Electro mechanical low frequency oscillation generated in a micro-grid (MG) when subjected to uncertain disturbances, and stochastic renewable penetration is more aggravated especially when connect...

In this paper, the cascaded control scheme is introduced for the first time to the rotor stability problem. Cascaded excitation and governing control schemes are introduced to damp rotor oscillations. PID cascaded control is used for its popularity and effectiveness. These controllers will be fine-tuned using a novel metaheuristic optimization technique, namely the Marine Predator Algorithm; which mimics the movement of marine predators when foraging. This technique is popular for always converging to a constant stable point. Our study will be performed on two systems, the simple single machine to infinite bus power system and the popular IEEE-39 bus system to study both local and global oscillations, respectively. Results show the effectiveness of the new proposed cascaded control scheme compared to the conventional scheme in improving the damping of the rotor oscillations without the need of a power system stabilizer. Results are provided as time domain simulation via MATLAB/SIMULINK.

This paper describes, the application of transient energy function and some laws of theoretical mechanics necessary to the problem of analysing Co-ordinated stabilizer in a multimachine power system. The co-ordinated stabilizing inputs for the exciter and governer loops to improve transient stability in the power system are defined. The different energies in the power system are analysed. If the power system is asymptotically stable in the first swing cycle, the rate of change of total transient energy must tend to zero. This constraint is accomplised by the proposed stabilizer. The stabilizer is designed on the base of balancing its forces with the necessary forces to damp swings of generator rotors. The effectiveness of the proposed stabilizer is demonstrated by applying it to a generating station in a 10-generator and 19-bus power system, which represents the reduced Egyptian Unified Network.

Straddle-type monorail ,as a unique technology, energy saving and environmental protection, is different from the subway of urban rail transit system. In order to study the curving performance of a new type of the straddle-type monorail vehicle with single-axle bogies ,the three-dimensional spatial dynamics model which consists of the vehicle model and track model designis proposed by the multi-body dynamics soft ADAMS. The monorail vehicle dynamic model which consists of three types of tire -track contact model and the nonlinear model of the horizontal stop is established. Based on the dynamic model, the influences such as pre pressure and curve super-high rate parameters of the curve passing for the dynamic characteristics are discussed. The simulation results show that the suitable preload for the guide and stabilizer tires of straddle-type vehicle with single-axle bogies is 5KN and after selecting the appropriate pre-pressure, the super-high rate is recommended to be 8%-10%.

Considering a simplified model of cables is an essential assumption in the design of state-estimator and vibration control of cable-driven parallel robots (CDPRs). Such an assumption however, impacts the effectiveness of controllers and state-estimators in such systems. This article presents a reaction-based stabilizer for nonmodel-based vibration control of CDPRs to address such model dependence. It is proved analytically that by using only three actuators and not involving the cable-connected winches, the proposed stabilizer regulates all undesired vibrations of the platform. It is also shown that the proposed stabilizer needs only the directly measurable position and velocity of its actuators to form its closed-loop control feedback signals. Effectiveness of the proposed system is more significant in CDPRs with considerable nonlinear effects of cables, where such effects are computationally costly to model, such that the performance of real-time controllers and state-estimators are spoiled. To provide a case study, a multibody nonlinear dynamic model of a suspended CDPR equipped-with the proposed stabilizer with zero cable damping effects is developed in SimMechanics/ MATLAB , where a fine-tuned proportional-derivative controller is applied on each actuator to suppress all vibrations of the system. In addition, a suspended CDPR with extremely stretchable nonlinear-stiffness elastomer cables is fabricated and tested, where performance of the proposed stabilizer to suppress the high-amplitude nonlinear oscillations of the whole system is demonstrated.

The initial disturbance of the projectile and the barrel vibration is the premiere factors influencing the firing accuracy of the moving tank. To better understand the launch progress of the moving tank, a novel mechanical–electrical-hydraulic co-simulation model of the moving tank under the influence of a stabilizer was established, and a contact model with clearance for projectile-barrel rigid-flexible coupling was presented. Therein, the projectile-barrel coupling relationship was described by a cylindrical joint with clearance, and an improved contact algorithm based on the L–N model (Lankarani–Nikravesh continuous contact force model) was introduced to calculate the projectile-barrel contact force. The established model was verified tentatively by comparing with previously published literature. The simulation results indicate that the projectile-barrel coupling affects both the cradle vibration characteristics and the barrel dynamic bending features of the moving tank. It causes the gun's pointing deviation towards the target and the pointing deviation of the projectile velocity at muzzle exit and ultimately affects the firing accuracy of the moving tank.

A power system stabilizer (PSS) design technique via model order reduction (MOR) for a modified single machine infinite bus (MSMIB) system using an improved whale optimization algorithm (IWOA) is p...

Linear active disturbance rejection control (LADRC) is applied as power system stabilizer (PSS) in power systems to damp the low-frequency oscillations. A tuning method for second-order LADRC is pr...

A mechanism for efficient self-tuning of a fuzzy logic-based PSS in real-time is presented. The proposed controller with a self-tuning mechanism can reduce low-frequency oscillations regardless of ...

Background: A large number of nature-based optimization methods have been proposed to use as efficient tools in scientific studies. Genetic Algorithm (GA), which operates based on human genetical evolution, has been an outstanding mostly used solver in a wide range of applications. This algorithm reflects the process of natural selection where the fittest individuals are selected for reproduction in order to produce offspring of the next generation. Initialization, selection, crossover, and mutation are the main parts of the GA population-based method which enables GA to have a prominent explorative feature. On the other hand, the Teaching Learning Based Optimization algorithm (TLBO) is of great performance during searching for the optimum solution among individuals. Therefore, it is expected that the combination of both algorithms in a certain logical way improves the optimization time. Objective: The study intends to determine ways of improving performance of the TLBO algorithm to solve a complex non-linear problem. Power system studies are one of the most complex problems for analysis. Therefore, a powerful heuristic optimization procedure would have a valuable contribution in solving such problems. In addition, the proposed heuristic algorithm will help scientists to apply the technique to their problems. Materials and Methods: According to the aforementioned explanation, a new efficient optimization approach is proposed which optimizes the parameters of multi-machine power system stabilizers (PSSs). The TLBO algorithm includes two different stages in its main structure, which are aptly called teacher and student stages. The student stage of TLBO is replaced by the genetic algorithm in order to improve the explorative feature of the main TLBO. The PSS parameters are obtained for four PSSs which are connected to four generators. Results: The performance of the proposed stabilizer is compared with other formerly designed stabilizers reported in the literature consisting of multi-band PSSs for two areas four-machine power system. Simulation results demonstrate the effectiveness and robustness of the proposed PSS in damping local and inter-area oscillation modes under various disturbances and confirm its superiority in comparison with the other types of PSSs. Conclusion: : A search heuristic method like the genetic algorithm can dramatically improve the performance of meta-heuristic optimization technique. In actuality, the TLBO as a meta-heuristic optimization technique suffers from a direct search of random solutions in its primary stage. Then, the TLBO relinquishes some parts of search space which may restrict the algorithm to find absolute maximums or minimums. In this condition, the GA with a great ability in searching the whole search space effectively improves the TLBO. According to the obtained results, the proposed algorithm, named Genetic-TLBO, obviates the conventional TLBO flaws successfully.

Recently, a stabilizer free weak Galerkin (SFWG) method is proposed in [ 14 ], which is easier to implement and more efficient. In this paper, we developed an SFWG scheme for solving the general second-order elliptic problem on triangular meshes in 2D. This new SFWG method will dramatically reduce the error between the $ L^{2} $-projection of the exact solution and the numerical solution.

Power systems are large non-linear systems that are often subject to low frequency electromechanical oscillations with a frequency of 0.5–2.5 Hz. Power system stabilizers (PSS) are commonly used as effective and economically efficient means to dampen electromechanical oscillations of generators and increase the stability of power systems. PSS can increase the power transmission stability limits by adding a stabilizing signal through the channels of the automatic excitation control system. The article presents the results of training a neural network based on which a fuzzy logic PSS is obtained for increasing the stability of electric power systems. The synchronous generator rotor speed deviation and acceleration were taken as input data for the fuzzy logic controller. These variables have a significant effect on damping the rotor's electromechanical oscillations. The characteristics of the power system equipped with the proposed fuzzy logic based PSS are compared with its characteristics with a PSS with non-optimized parameters and without a PSS.

In this paper, we propose a new stabilizer-free and pressure-robust weak Galerkin finite element method for the Stokes equations with superconvergence on polytopal mesh in the primary velocity-pres...

Objective To analyze the effects of whole body vibration on electromyographic activity of the core muscles. Methods This is an observational cross-sectional study composed of 30 males who practice physical activity. The amplitude of the electromyographic activation (Root Mean Square - RMS) of the rectus abdominis, external oblique, longissimus thoracis, multifidus muscles were evaluated during supine bridge, side plank and frontal plank exercises, performed with and without vibration (frequency: 50 Hz and amplitude: 4 mm). A significance level of 5% was assigned for all analyzes. Results Whole body vibration did not alter the amplitude of electromyographic activity for any of the evaluated muscle groups, showing no difference between the conditions with and without vibration during the performance of the proposed exercises. Conclusion Under the conditions analyzed in this study, the vibrating platform does not change the activation amplitude of core muscles, suggesting that the use of whole body vibration is not necessary as an additional method to increase muscle activity during stabilization exercises in healthy men.

When the vehicle is traveling at high speed and suddenly steers, a rollover phenomenon may occur. The main cause of this phenomenon is the appearance of a centrifugal force, which is proportional to the mass and the square of the velocity. In order to limit this situation, the method of using the hydraulic stabilizer bar (active stabilizer bar) has been proposed. The performance of the hydraulic stabilizer bar is highly dependent on the control method, which has been designed to ensure the stabilizer bar’s operation. Previous research often only used simple dynamics models and conventional linear control methods. Therefore, the performance of the stabilizer bar is not guaranteed. At the same time, the factors affecting the movement of a vehicle are not mentioned. This will cause inaccuracies. This research used a spatial dynamics model combined with a non-linear double-track dynamics model, which fully describes the effects of vehicle oscillations. Besides, the two-input Fuzzy control method is also proposed. This is a completely novel model, and it is not like the previous models that have been used to study the stabilizer bar. The results of this research show that if the vehicle uses the hydraulic stabilizer bar controlled by a two-input Fuzzy controller, the values of the roll angle and roll index have been reduced. As a result, stability and safety have been significantly improved. The achievements of this research will be the basis for the development of other intelligent control methods in the future.

Unmanned Aerial Vehicles possess characteristics that make them suitable for use in multiple areas. This project proposes the design of a small fixed-wing UAV that can be used to carry a payload of around 1 kg. The design is developed performing aerodynamic, structural, and stability analysis using analytical methods as well as commercial code. It is then fabricated into a physical model. Take-off is achieved by launching with the hand or a launcher. Low stall speed allows the UAV to land softly during landing. Twin vertical stabilizers are used, one at each end of the horizontal stabilizer, to reduce the effect of propeller slipstream. Pusher configuration is chosen to allow unobstructed view when imaging devices are attached to the nose of the UAV.

The paper presents the results of the numerical calculation of the flow around hybrid unmanned aircraft with X-tail stabilizers. This aircraft design is an innovative combination of a gyroplane and a multi-rotor. The aerodynamic properties of the two-part X-tail stabilizer were analysed. The aerodynamic forces and moments on this element of the aircraft were specified from the CFD simulation calculations for the defined values of the angle of attack and the slip angle, and particular attention was paid to the differences between the upper and lower parts of the stabilizer. In addition, the turbulence kinetic energy on the surface of the vortex core region were analysed to conduct a qualitative and quantitative analysis of energy losses in flow, resulting from local separation and vortices. The obtained results allow for conducting further aerodynamic comparative analyses on other types of stabilizers.

Minimally invasive image-guided interventions have changed the face of procedural medicine. For these procedures, safety and efficacy depend on precise needle placement. Needle targeting devices help improve the accuracy of needle placement, but their use has not seen broad penetration. Some of these devices are costly and require major modifications to the clinical workflow. In this article, we developed a low-cost, disposable, and easy-to-use angulation tracking device, which was based on a redesigned commercial passive needle holder.The new design provided real-time angulation information for needle tracking. In this design, two potentiometers were used as angulation sensors, and they were connected to two axes of the passive needle holder's arch structure through a 3 D-printed bridge structure. A control unit included an Arduino Pro Mini, a Bluetooth module, and two rechargeable batteries. The angulation was calculated and communicated in real time to a novel developed smartphone app, where real-time angulation information was displayed for guiding the operator to position the needle to the planned angles.The open-air test results showed that the average errors are 1.03° and 1.08° for left-right angulation and head-foot angulation, respectively. The animal cadaver tests revealed that the novel system had an average angular error of 3.2° and a radial distance error of 3.1 mm.The accuracy was comparable with some commercially available solutions. The novel and low-cost needle tracking device may find a role as part of a real-time precision approach to both planning and implementation of image-guided therapies.

Selection of a suitable stabilization system for motor yachts is a challenging problem for both owners and designers. Also, this is a good sample of multicriteria decision-making problem that includes many criteria required to be assessed at the same time. The present work aims to propose an extended Technique for Order Preference by Similarity to Ideal Solution methodology based on single-valued neutrosophic numbers which represent the uncertainty of real-world applications. A questionnaire was applied to a group of experts who were asked to evaluate four different stabilizer alternatives according to the 15 criteria determined. Evaluations of the experts were analyzed through the proposed methodology, and results were presented and discussed.

The weak Galerkin (WG) finite element method is an effective and flexible general numerical techniques for solving partial differential equations. A simple weak Galerkin finite element method is introduced for second order elliptic problems. First we have proved that stabilizers are no longer needed for this WG element. Then we have proved the supercloseness of order two for the WG finite element solution. The numerical results confirm the theory

In a few of the isolated DC power-transmission systems with hydropower units (and the associated water hammer effect), inappropriate governor control parameters may weaken the system damping and stability. It has the potential to result in ultra-low-frequency oscillations (ULFO) which is below 0.1 Hz. To carry out this issue, a linearized state-space model of a multi-machine system that includes hydropower and steam turbine governor control systems is presented in this paper. The oscillation mode of ULFO about the damping characteristics of the governor control system is analyzed by the damping torque analysis method. A governor power system stabilizer (GPSS) design model predicated on phase compensation principle to heighten the damping of the governor control system to subdue ULFO is planned. To verify its effectiveness, the designed GPSS is applied to a single-machine system, a 4-machine 2-area system as well as the Yunnan power grid system of China. The simulation results demonstrate that GPSS effectively suppresses ULFO with heightened ULFO damping by the optimized settings of governor control parameters.

Background: Suspension training systems, which use body weight resistance under unstable conditions, may be effective for muscle strengthening in persons with scapular dyskinesis or subacromial impingement syndrome. Hypothesis: Greater arm, scapular, and trunk muscle recruitment will occur during horizontal abduction row exercises. Study Design: Descriptive laboratory study. Level of Evidence: Level 5. Methods: Surface electromyography data were collected from 28 participants (14 men, 14 women). A total of 13 right-sided muscles were studied at a sampling frequency of 1000 Hz. Maximal voluntary isometric contractions (MVICs) were established. Participants completed 3 repetitions per exercise in random order. We compared muscle recruitment during 3 rowing exercises: low row, high row, and horizontal abduction row. Data were compared with repeated-measures analyses of variance and post hoc Bonferroni corrections. Results: For high row and horizontal abduction row conditions, the upper, middle, and lower trapezius and posterior deltoid demonstrated >60% MVIC magnitudes of recruitment, and the upper erector spinae demonstrated 40% to 60% MVIC magnitudes of recruitment, respectively. In contrast, in the low row exercise, 40% to 60% MVIC magnitudes of recruitment were observed only in the middle trapezius, latissimus dorsi, and posterior deltoid. Conclusion: With the suspension system, high row and horizontal abduction row exercises promote muscle strengthening (>50% MVIC) in the upper, middle, and lower fibers of the trapezius, posterior deltoid, and upper erector spinae. Clinical Relevance: Rowing exercises performed with suspension straps may be recommended for muscle strengthening in patients with scapular dyskinesis and subacromial impingement syndrome as well as for healthy persons in need of enhanced scapular muscle performance.

Articulated wheeled loader vehicles have frequent rollover accidents as they operate in the complex outdoor environments. This article proposes an active anti-rollover control method based on a set of single-frame control moment gyro stabilizer installed on the rear body of the vehicle. The rollover dynamic model is first established for articulated wheeled loader vehicle with gyro stabilizer. The proposed control strategy is then applied in simulation to verify the rollover control effect on the vehicle under steady-state circumferential conditions. Finally, a home-built articulated wheel loader vehicle with gyro stabilizer is used to further verify the proposed control strategy. The results show that the vehicle can quickly return to the stable driving state and effectively avoid the vehicle rollover when a suitable anti-roll control moment can be provided by the gyro stabilizer. As a result, the articulated wheeled loader vehicle is able to operate safely in a complex outdoor environment.