Papers by Keyword: Dynamic Stability

Abstract: Dynamic robots capable of navigating confined and unpredictable environments are increasingly needed in industrial applications. This study aimed to design and evaluate a two-legged wheeled self-balancing robot platform to achieve stable and efficient motion in narrow and dynamic settings. The robot was built using an Arduino Mega 2560 microcontroller, MPU6050 IMU sensor, TD8129MG servo motors, and LN298N motor drivers, with balance maintained by a proportional-integral-derivative (PID) controller. Static stability tests confirmed reliable balance at a -2.00° pitch angle with optimized PID gains of K_p = 120, K_i = 0.1, and K_d = 150. Dynamic experiments under duty cycles of 59%, 78%, and 98% showed that the 78% configuration provided the optimal compromise, enabling smooth motion at 0.23 m/s with minimal oscillations, while lower duty cycles caused instability and higher cycles introduced excessive vibrations. These results demonstrate that the developed robot effectively balances speed and stability, offering a compact and maneuverable solution for industrial tasks in constrained spaces. The study concludes that this platform provides a strong foundation for practical applications, with future work directed toward advanced control strategies and autonomous navigation to enhance adaptability and energy efficiency in real-world environments.

Abstract: Flexible alternating current transmission systems (FACTS) deployments and applications are on the increase in modern day power network systems because of their advantages over conventional ways of power network physical expansion. Therefore, a comprehensive review of FACTS controllers with their various applications is carried out in this paper. Formation of different applications and advantages of FACTS devices into voltage control, power flow control, system stability control, power quality control, and economic benefits as inferred from the literatures is among the vantage points of this presentation. FACTS background alongside different techniques of deployments, leading to various applications and performance of these devices, hitherto organized structurally based on target objectives are also explored, presented and discussed. Summarily, this study provides an overview of the background, topological structures, deployment techniques and cutting-edge utilization of FACTS controllers, with a view to acquainting power players, electrical engineers, network designers as well as researchers, with the trends in the development, status and future direction of FACTS applications. Convincingly, the content of this article will benefit all the stakeholders in the area of FACTS deployments and utilizations.

Abstract: In nano-dimension, the strength of the material is considerable, and the failure is unavoidable in a torsional mode. Because of this reason, the free and forced torsional vibrations of single-walled carbon nanotube (SWCNT) are investigated in this paper. For dynamic analysis, the moving harmonic torsional load is exerted to SWCNT. The related boundary condition and equation of motion are derived by Hamilton’s principle, and the equation is discretized by the Galerkin method. In order to demonstrate the nonlocality and small–scale effect, Eringen’s theory based on nonlocal elasticity theory is applied. A clamped-clamped (C-C) boundary condition is fitted for the end supports. The influences of the aspect ratio and mode number on the free natural frequency are investigated. Furthermore, the dynamic effects of nonlocal parameter, velocity, thickness, length, and excitation-to-natural frequencies on dimensional and nondimensional angular displacements are indicated. Moreover, the natural frequency was investigated due to the variation of the aspect ratio.

Abstract: Asphalt mixture is a kind of a viscoelastic material with viscoelastic characteristic of time-temperature equivalence. This paper, from the engineering practical consideration, and the perspective of time-temperature equivalence principle, based on the Rutting Test of Asphalt Mixture,has obtained equivalence relations of the effect of wheel speed and temperature on asphalt mixture rut index by different wheel speed and different temperatures rutting test, so as to provide the data support for the research of anti-rutting mechanism of asphalt pavement.

Abstract: There are described properties of hardening multi-functional silicate composite during its long-term dynamical loading in the paper. Studied composite was developed for special application in permanent way structure in Prague underground. Dynamic loading was carried out on the laboratory model, in which the composite was applied as a bench of the rail anchoring. Due to loading in early ages was also studied the option of steel fibers addition. Results obtained confirmed impressive potential for practical use during new tracks construction, and quick repairs as well, because of rapid evolution of mechanical properties and sufficient resistance to dynamic loading. Silicate composite with fibers addition had better mechanical properties, however significant improvement during dynamic loading was not recorded in comparison with the reference mixture without fibers. Generally, new composite material confirmed great potential for practical use in transportation industry.

Abstract: The exact coincidence of external excitation and basic eigen-frequency of a single degree of freedom (SDOF) nonlinear system produces stationary response with constant amplitude and phase shift. When the excitation frequency differs from the system eigen-frequency, various types of quasi-periodic response occur having a character of a beating process. The period of beating changes from infinity in the resonance point until a couple of excitation periods outside the resonance area. Theabove mentioned phenomena have been identified in many papers including authors’ contributions. Nevertheless, investigation of internal structure of a quasi-period and its dependence on the difference of excitation and eigen-frequency is still missing. Combinations of harmonic balance and small parameter methods are used for qualitative analysis of the system in mono- and multi-harmonic versions. They lead to nonlinear differential and algebraic equations serving as a basis for qualitativeanalytic estimation or numerical description of characteristics of the quasi-periodic system response. Zero, first and second level perturbation techniques are used. Appearance, stability and neighborhood of limit cycles is evaluated. Numerical phases are based on simulation processes and numerical continuation tools. Parametric evaluation and illustrating examples are presented.

Abstract: A newly polymer cement mortar to repair the rutting and bump of the pavement was developed and studied. In order to satisfy the required performance of the asphalt pavement as repair material, the polymer cement ratio of this mortar went up more than fifty percent. The basic properties such as workability, mechanical properties and adhesion durability of the polymer cement mortar was firstly investigated. Subsequently, the dynamic stability of the composite specimens repaired by the polymer cement mortar was clarified by wheel tracking tests. Finally, the availability of this mortar applied for the repair of the pavement was confirmed by the track running test more than two years.

Abstract: Power system stability means the ability to develop restoring forces equal to or greater than the disturbing forces to maintain the state of equilibrium. Successful operation of a power system depends largely on providing reliable and uninterrupted service to the loads by the power utility. The stability of the power system is concerned with the behavior of the synchronous machines after they have been disturbed. If the disturbance does not involve any net change in power, the machines should return to their original state. Due to small disturbances, power system experience these poorly damped low frequency oscillations. The dynamic stability of power systems are also affected by these low frequency oscillations. This paper presents to analyze and obtain the optimum gain for damping oscillation in SMIB by using Riccati matrix method to improve dynamic power system stability. The result shows that with suitable gain which is act as a stabilizer that taken from Riccati matrix, the oscillations of rotor speed and rotor angle can be well damped and hence the system stability is enhanced.

Abstract: Modern development of distributed sources of electricity in Russia is impossible without the development of means to improve its dynamic stability during sudden changes of regime. In this paper a solution of using a pseudo-direct drive is proposed. The relevance of the study is related to the fact that Russia distributed energy sources in isolated power systems have little power. Unfortunately, there are some drawbacks of such power systems in terms of electricity problems associated with the loss of dynamic stability during short circuits.

Abstract: The phenomenon of lubricant cavitation in hydrodynamic bearings and its effect on the stability has been rigorously studied and reported in the literatures. In certain cases, cavitation has significant effect on the dynamic and stability characteristics of the rotor-bearing system. With a proper control of the cavitation condition and groove location, stability can be achieved over a wide range of operating speed, in the case of elliptical journal bearings. On the other hand, the stability is not affected by the presence of vapor cavitation, in the case of multi-lobe journal bearings with the oil supplied at atmospheric pressure. For the unstable, submerged, circular bearings, vapor cavitation phenomena results in a distinctive vibration response observable on the vibration plots. The stability of the elliptical journal bearings under the influence of vapor cavitation erosion was analyzed. It is found that vapor cavitation erosion on elliptical bearings results in instability of the whirling shaft. Collapse of the vapor cavitation bubbles causes erosion wear that falls within the pressure zone of the elliptical bearing, thus causing the instability.