Papers by Keyword: Stability

Abstract: This project presents the analyzed results of an integrated offshore wind and seashore wave farm fed to an onshore power grid through a unified power flow controller (UPFC) to simultaneously achieve power-fluctuation mitigation and stability improvement. A damping controller of the proposed UPFC is designed by using modal control theory to render adequate damping characteristics to the studied system. A frequency-domain scheme based on a linear system and a time-domain scheme based on a nonlinear system. From time domain analysis, the UPFC is designed. The proposed UPFC joined with the designed damping controller can effectively stabilize the studied integrated OWF and SWF under various interruption conditions. The fluctuated power injected in to the power grid can also be effectively mitigated by the proposed control scheme.

Abstract: In this paper, a two phase flow distribution in a horizontal pipe is numerically analyzed by solving one dimensional steady state momentum equation for predicting the pressure drop (∆P), quality of steam at outlet of the pipe (X), void fraction (α). The heat absorbed by the pipe (Q) and the mass flow rate (W) of water are varied over a wide range to investigate the above parameters. The locations of the two phase mixture are discussed. Pressure drop along the pipe is inconsistent for different flow rate so, the stable and unstable steady state solution is also carried out using Linear Stability analysis. The present numerical results are compared with the reported data from the literature and found that they are in good agreement. This study is used to calculate the pressure, temperature, hold up and quality within the horizontal pipe.

Abstract: This paper presents the complex dynamic analysis of a flexible rotor–bearing system supported by two turbulent micropolar fluid film journal bearings under nonlinear suspension. The Modified Reynolds equation based on the assumptions of turbulent flow and the micropolar parameters has been considered. The system considers Short bearing approximation to simplify the numerical computations. The pressure distribution thus obtained is used to find out the resulting forces about the journal center in the radial and tangential directions. The Non-dimensional dynamic equations are derived considering appropriate non dimensional parameters and solved using MATLAB for a wide range of non-dimensional speed ratios. Plots of the journal center trajectories and rotor center trajectories are obtained. The results show that the system undergoes undesirable nonsynchronous vibrations due to bearing center displacement. Micropolar fluid is found to stabilize the system even when the flow of the system becomes turbulent. The study presented enhances the understanding of the nonlinear dynamics of turbulent journal bearings with respect to dimensionless parameters.

Abstract: Nanofluid is nanomaterial suspended in base fluid. Nanoparticle enhances various properties of base fluid mainly heat transfer characteristics. Also sometime nanoblends means hybrid nanofluid is used. This article mainly states how nanofluids are formed from nanoparticle and there types. This paper reviews and summaries the recent work in experimental and theoretical heat transfer characteristic of nanofluid as well as nanoblends and it is helpful in identifying the nanofluid that can be used in heat pipe for further research.

Abstract: The torque motor is a precision mechatronic component used to convert low electric signal into linear mechanical displacement of the Jetpipe. Such torque motors are categorized under multi disciplinary engineering systems, which are complex in nature and also induces challenges to integrate with hydraulic system. This paper applies model-based system design approach of jetpipe servovalve torque motor to study the effect of critical parameters like armature length and air gap, feedback spring stiffness, and flexure tube stiffness on the dynamic performance of the were studied.

Abstract: This paper deals with two frequency parametric excitation in presence of internal resonance. The cubic nonlinearity is inserted into the equation of motion by considering the mid-line stretching of the beam. The perturbation method of multiple scales is applied directly to the governing nonlinear fourth order integro-partial differential equation of motion. This leads to a set of first order differential equations known as the reduced equations or normalized reduced equations, which are utilized to determine the additional instability zones, appeared in the trivial state stability plot, the bifurcation and stability of fixed-points, periodic, quasi-periodic, mixed mode and chaotic responses. The transition of system behaviour from stable periodic to unstable chaotic occurs through intermittency route

Abstract: Mobile prediction idea refers to predicting link expiration time with relative velocity and relative position between different nodes. In ad hoc networks, mobile prediction idea is adopted in MSWCA, and cluster stability is measured by link expiration time. MSWCA only considers on intra-cluster stability, and neglects inter-cluster stability. Aiming at the above problem, MPICA (Mobile Prediction Idea based Clustering Algorithm) was proposed. Firstly, involved concepts were given with mathematical quantitative description. Secondly, the realization process of MPICA was described. Lastly, the complexity of MPICA was analyzed. MPICA considers intra-cluster and inter-cluster stability at the same time, which is in favor of improving cluster stability and reducing cluster maintenance overheads.

Abstract: In this paper, we employ iterative analysis method to obtain both the existence and the stability of first order functional differential equations with impulses for periodic boundary value problem. Some new results are obtained.

Abstract: Stability of coal-water suspension (WCS) is one of the main criteria for obtaining fuel efficient. In the present work we investigated the sedimentation stability of coal-water suspension of 35% (in the presence and absence of hexane) stabilized by sodium dodecyl sulfate. Found that pretreatment of coal hexane (before being crushed) and further stabilization of coal-water suspension of 35% sodium dodecyl sulfate at concentrations of 0.8-.1.0% helps to ensure a stable dispersion system.

Abstract: With accelerating urbanization construction, especially with the scale enlargement of high-rise buildings, the crane’s hoist boom length and height is increasing.The hoist boom will produce strength and buckling failure easily on the working condition of complex combination, such as gravity, wind load and inertia force.The TC6010 crane was analyzed the mechanics by finite element method. This thesis got its stability and strength data in four kinds of working conditions. It can provide certain reference value for other crane’s design and calculation.