A Chaotic Oscillator Based on Meminductor, Memcapacitor, and Memristor

In this paper, a hyperchaotic circuit consisting of a series memristor, meminductor, and memcapacitor is proposed. The dimensionless mathematical model of the system is established by the state equation of the circuit. The stability of equilibrium point of the system is analyzed by using the traditional dynamic analysis method. Then, the dynamical characteristics of the chaotic system with parameters are analyzed in detail. In addition, the system also has some particular phenomena such as attractor coexistence and state transition. Finally, the circuit is realized by DSP, and the result is consistent with that of numerical simulation. This proves the accuracy of the theoretical analysis. Numerical simulation result shows which hyperchaotic system has very abundant dynamical characteristics.

A Semi-Active Controller for an Aircraft Landing Gear Equipped with Magnetorheological Damper

The magnetorheological (MR) damper is the newest approach to replace the traditional passive damper which cannot change their dynamics in response to different operating conditions of the aircraft landing gear. This paper presents the simulation study of a semi-active controller for a landing gear equipped MR damper. Furthermore, a new method combined skyhook control with force control, called hybrid control, is developed to improve the performance of the MR damper landing gear. Finally, the numerical simulation result of the landing gear using SIMSCAPE-Simulink is discussed.

Evaluation of Contact Forces in the Vertical Connection of a Flexible Riser in the Subsea Equipment

Flexible risers are commonly used in ultra deepwater offshore fields to convey fluids from the subsea equipment to the floating production unit. During the development of the production systems, the flexible pipe installation is a critical operation. In this scenario, an operational procedure for the installation frequently used in offshore Brazil is known as Direct Vertical Connection. In this concept, the Vertical Connection Module (VCM) is connected to the flexible pipe through a flanged joint, and lowered in to the subsea equipment with assistance of an installing cable. During the installation procedure, excessive loads may occur in the VCM due to reaction loads induced by the flexible pipe. The present paper aims to describe the Direct Vertical Connection installation and to propose a methodology to study the forces induced by the flexible pipe into the VCM during such operation. For this purpose, a numerical model is developed for the Direct Vertical Connection and it is represented to simulate the installation procedure through a commercial software OrcaFlex. The dynamic behavior of the system is investigated by varying the payout velocity of the installing cable, and the results are shown in terms of bending moment, wall tension and shear forces acting in the flange of the VCM. Numerical simulation result in the present work allows to evaluate the range of loading which acts during the Direct Vertical Connection to help operational design of the installation process, and avoid failure of components during the procedure.

Analisis Kestabilan dan Usaha Pemanenan Model Predator Prey Tipe Holling III dengan Keuntungan Maksimum

In this paper discussed Stability Analysis and Harvesting Effort at second Predator Prey Populations model Holling Type III with Maximum Profit. The step this research is to determine the equilibrium point, linearize the model, stability analysis of the equilibrium point, and numerical simulation. Result shows that obtained an interior point T that asymptotic stable based on Hurwitz stability test then obtained maximum profit from exploitation harvesting effort of second predator prey populations. This second populations will always exist, even though exploited with harvesting effort done by humans. Harvesting effort of second predator-prey populations given maximum profit that occur on critical points of surface profit function

Numerical Simulation of Rotor in Hover and Forward Flight

The flow around rotor is numerical simulated in hover and forward flight based on multi-structured grid. In hover the flow field can be transformed into a steady-state flow field in the rotating coordinate system. The experimental data of Caradonna and Tung rotor is used to verify the numerical simulation result. The numerical results compare well with the experimental data for both non-lifting and lifting cases. Non-lifting forward flight is simulated and the prediction capabilities have been validated through the ONERA two-blade rotor. The pressure distributions of different positions under different azimuth angles are compared, which is in good agreement with the experimental data. There is unsteady shock wave when forward flight. Dual-time method is used to obtain unsteady flow field with rigid moving grid in the inertial system.

The Research of Calculation Method on Vertical Natural Frequency of the New Full-Prefabricated Floor

New-type floor is composed of three kinds of slabs joined together through fittings. It is a kind of anisotropic two-way slab. In order to study the calculation method of natural frequency, series method, variable thickness method and variable stiffness method are adopted to calculate the natural frequency. The calculation results of three methods are compared with test result and numerical simulation result. The conclusion is that the calculation result of the variable stiffness method is the closest to the real natural frequency of new-type floor.

Constraint Mechanical Model and Investigation for Rub-Impact in Aero-Engine System

A mechanical model for rub-impact was proposed considering the additional constraints caused by rubbing. Based on the constraint mechanical model, some characteristics of response such as resonant range expansion, contact unstability and amplitude jump during rubbing were studied. The influences of typical parameters on rotor’s vibration response with rub constraint were also evaluated. The result reveals that additional constraint stiffness causes the unstable contact range and the resonant range to be wider. While greater friction coefficient between rotor and casing results in smaller response and narrower resonant range. A simplified dynamic model for the aero-engine was built, which takes the constraint effect into account. The numerical simulation result shows that in addition to the resonant range expansion caused by the constraint, the rotor response is also closely related to rubbing location and mode shapes. The rotor response shows a feature of quasi-periodic in slight rubbing, while the rotor motion tends unstable in heavy rubbing.

The Research and Application of FLAC3D in Optimization of Roadway Support

This article describes the basic process of numerical simulation, and an example of Xinyu coal mine roadway numerical simulation research. And the support scheme is proposed by the numerical simulation result.

Enhancing reproducibility of numerical simulation result on the C-Coupler platform

Reliable numerical simulation plays a critical role in climate change study. The reliability includes the technical reproducibility, i.e. bit-identical results of numerical simulation can be reproduced. It is very important for model development and scientific researches but has not been satisfactorily addressed yet so far. To address the technical reproducibility, necessary information about it is firstly analyzed, and how to enhance it on the Community Coupler (C-Coupler) platform, a uniform runtime environment that can operate various kinds of model simulations in the same manner, is then detailed. Moreover, we share a series of experiences and suggestions with scientists and model groups for achieving the technical reproducibility. We believe that, the proposed implementations, experiences and suggestions can be easily extended to other model platforms, and can prospectively advance model development and scientific researches in future.