scholarly journals Stability Analysis of Soil Flow Protector and Design Method for Estimating Optimal Length

2021 ◽  
Vol 11 (16) ◽  
pp. 7314
Author(s):  
Suwon Son ◽  
Moonbong Choi ◽  
Jaewon Yoo
Keyword(s):  
Design Method ◽  
Urban Infrastructure ◽  
Ground Settlement ◽  
Optimal Length ◽  
Scaled Model ◽  
Sandy Ground ◽  
Efficient Construction ◽  
Settlement Ratio ◽  
Soil Flow ◽  
The Stability

Underground cavities can develop below structures, leading to ground settlement and hindering the development of urban infrastructure. Soil flow protectors (SFPs) have been developed to prevent and alleviate problems due to the formation of such cavities. In this study, we performed scaled model experiments to develop a design method for an SFP with an adequate safety factor under different installation lengths of its upper and lower parts in sandy ground. The installation of the SFP reduced the average surface settlement ratio to the range of 0.44–0.72, thus demonstrating its effectiveness in reducing ground settlement. In addition, we proposed a relational equation for determining the optimal length ratio of the SFP and the settlement ratio. An analysis of the influencing factors showed that the lower part of the SFP influenced the settlement reduction, whereas the upper part influenced the stability of the SFP depending on the ground settlement ratio. Finally, we have proposed an optimal length equation for the SFP and presented a flowchart for the design method. The results of this study can serve as a design basis for the efficient construction of infrastructure.

scholarly journals Suboptimal Disturbance Observer Design Using All Stabilizing Q Filter for Precise Tracking Control

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1434 ◽  
Author(s):  
Wonhee Kim ◽  
Sangmin Suh
Keyword(s):  
Design Method ◽  
Industrial Applications ◽  
Point Of View ◽  
Observer Design ◽  
Linear Matrix ◽  
External Disturbances ◽  
Closed Loop Systems ◽  
Control Target ◽  
The Stability ◽  
Unified Index

For several decades, disturbance observers (DOs) have been widely utilized to enhance tracking performance by reducing external disturbances in different industrial applications. However, although a DO is a verified control structure, a conventional DO does not guarantee stability. This paper proposes a stability-guaranteed design method, while maintaining the DO structure. The proposed design method uses a linear matrix inequality (LMI)-based H∞ control because the LMI-based control guarantees the stability of closed loop systems. However, applying the DO design to the LMI framework is not trivial because there are two control targets, whereas the standard LMI stabilizes a single control target. In this study, the problem is first resolved by building a single fictitious model because the two models are serial and can be considered as a single model from the Q-filter point of view. Using the proposed design framework, all-stabilizing Q filters are calculated. In addition, for the stability and robustness of the DO, two metrics are proposed to quantify the stability and robustness and combined into a single unified index to satisfy both metrics. Based on an application example, it is verified that the proposed method is effective, with a performance improvement of 10.8%.

scholarly journals Actuator Saturated Fuzzy Controller Design for Interval Type-2 Takagi-Sugeno Fuzzy Models with Multiplicative Noises

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 823
Author(s):  
Wen-Jer Chang ◽  
Yu-Wei Lin ◽  
Yann-Horng Lin ◽  
Chin-Lin Pen ◽  
Ming-Hsuan Tsai
Keyword(s):  
Nonlinear Systems ◽  
Fuzzy Controller ◽  
Controller Design ◽  
Actuator Saturation ◽  
Design Method ◽  
Fuzzy Model ◽  
The Stability ◽  
Interval Type ◽  
Takagi Sugeno

In many practical systems, stochastic behaviors usually occur and need to be considered in the controller design. To ensure the system performance under the effect of stochastic behaviors, the controller may become bigger even beyond the capacity of practical applications. Therefore, the actuator saturation problem also must be considered in the controller design. The type-2 Takagi-Sugeno (T-S) fuzzy model can describe the parameter uncertainties more completely than the type-1 T-S fuzzy model for a class of nonlinear systems. A fuzzy controller design method is proposed in this paper based on the Interval Type-2 (IT2) T-S fuzzy model for stochastic nonlinear systems subject to actuator saturation. The stability analysis and some corresponding sufficient conditions for the IT2 T-S fuzzy model are developed using Lyapunov theory. Via transferring the stability and control problem into Linear Matrix Inequality (LMI) problem, the proposed fuzzy control problem can be solved by the convex optimization algorithm. Finally, a nonlinear ship steering system is considered in the simulations to verify the feasibility and efficiency of the proposed fuzzy controller design method.

Control of the Corner Separation in a Linear Cascade by Trailing Gaps

2017 ◽  
Author(s):  
Wenfeng Zhao ◽  
Bin Jiang ◽  
Qun Zheng
Keyword(s):  
Flow Field ◽  
Suction Surface ◽  
Optimal Length ◽  
Corner Separation ◽  
Linear Cascade ◽  
High Loss ◽  
Axial Compressors ◽  
Pressure Surface ◽  
Sst Turbulence Model ◽  
The Stability

Hub corner is the high-loss area in the blade passages of turbo machinery. It is well known that the flow separation and vortex development in this area affects directly not only the energy losses and efficiency, but also the stability of axial compressors. Linear compressor cascades with partial gaps and trailing gaps which can blow away the corner separation by the pressure difference between the suction surface and pressure surface are numerically simulated in this paper. A proposed linear cascade model with gaps has been built. The steady flow field in a linear cascade with different length gaps is studied by numerical simulation of RANS with SST turbulence model and γ-Reθ transition model focusing on the streamline structure between the corner separation vortex and the gap leakage vortex, especially the interaction of the two vertical vortex. When the length of trailing edge gaps is enough (in this paper, the optimal length of the gap is 30% chord), the corner vortex basically disappears completely. At the same time, the mode of flow field changes from the closed separation to the open separation.

scholarly journals Nonlinear Blade Stability for a Scaled Autogyro Rotor at High Advance Ratios

2020 ◽  
Vol 65 (1) ◽  
pp. 1-19
Author(s):  
Djamel Rezgui ◽  
Mark H. Lowenberg
Keyword(s):  
High Speed ◽  
Flow Speed ◽  
Numerical Continuation ◽  
Control Input ◽  
Nonlinear Phenomenon ◽  
Scaled Model ◽  
Underlying Mechanisms ◽  
Slowed Rotor ◽  
The Stability ◽  
Blade Pitch Angle

Despite current research advances in aircraft dynamics and increased interest in the slowed rotor concept for high-speed compound helicopters, the stability of autogyro rotors remains partially understood, particularly at lightly loaded conditions and high advance ratios. In autorotation, the periodic behavior of a rotor blade is a complex nonlinear phenomenon, further complicated by the fact that the rotor speed is not held constant. The aim of the analysis presented in this article is to investigate the underlying mechanisms that can lead to rotation-flap blade instability at high advance ratios for a teetering autorotating rotor. The stability analysis was conducted via wind tunnel tests of a scaled autogyro model combined with numerical continuation and bifurcation analysis. The investigation assessed the effect of varying the flow speed, blade pitch angle, and rotor shaft tilt relative to the flow on the rotor performance and blade stability. The results revealed that rotor instability in autorotation is associated with the existence of fold bifurcations, which bound the control-input and design parameter space within which the rotor can autorotate. This instability occurs at a lightly loaded condition and at advance ratios close to 1 for the scaled model. Finally, it was also revealed that the rotor inability to autorotate was driven by blade stall.

scholarly journals Study on the High-Speed and Close of the UVA Cooperative Formation Controller Design

2018 ◽  
Vol 36 (2) ◽  
pp. 345-352
Author(s):  
Jialong Zhang ◽  
Jianguo Yan ◽  
Pu Zhang ◽  
Xiaoqiao Qi ◽  
Maolong Lü
Keyword(s):  
Dynamic Characteristic ◽  
High Speed ◽  
Controller Design ◽  
Design Method ◽  
Formation Flight ◽  
Unsteady Aerodynamic ◽  
Aerodynamic Model ◽  
Thrust Vector ◽  
The Stability ◽  
Rudder Angle

Aiming at the high-speed flight of the UAVs cooperative formation, when a single UAV has occurred, need to exit the formation flight and be close or super close to form of the formation quickly. A fast close cooperative formation controller design method is proposed to make up for low the fighting robustness, and be shortcomings of timeliness poorly and analyze the dynamic characteristic of UAV formation flight. Taking the external factors known into consideration, setting up for the longitude maneuver of nonlinear thrust vector and unsteady aerodynamic model, according to the formation velocity, flat tail rudder angle and thrust vector and pitch angle velocity for corresponding input commend signals for the controller to research the dynamic characteristic of UAV formation flight. Meanwhile, the formation flight distance error is the convergence to a fixed value, and the stability of the cooperative formation flight is good. The simulation of results show that the controller can effectively improve the speed of the close or super close to formation, and maintain the stability of the formation flight, which provides a method of the close or super close formation flight controller design.

scholarly journals Backstepping sliding mode controller improved with fuzzy logic: Application to the quadrotor helicopter

2012 ◽  
Vol 22 (3) ◽  
pp. 315-342 ◽  
Author(s):  
Samir Zeghlache ◽  
Djamel Saigaa ◽  
Kamel Kara ◽  
Abdelghani Harrag ◽  
Abderrahmen Bouguerra
Keyword(s):  
Fuzzy Logic ◽  
Control Method ◽  
Sliding Mode ◽  
Design Method ◽  
Stability And Convergence ◽  
Sliding Mode Controller ◽  
Quadrotor Helicopter ◽  
Nonlinear Control Method ◽  
The Stability ◽  
Yaw Angle

Abstract In this paper we present a new design method for the fight control of an autonomous quadrotor helicopter based on fuzzy sliding mode control using backstepping approach. Due to the underactuated property of the quadrotor helicopter, the controller can move three positions (x;y; z) of the helicopter and the yaw angle to their desired values and stabilize the pitch and roll angles. A first-order nonlinear sliding surface is obtained using the backstepping technique, on which the developed sliding mode controller is based. Mathematical development for the stability and convergence of the system is presented. The main purpose is to eliminate the chattering phenomenon. Thus we have used a fuzzy logic control to generate the hitting control signal. The performances of the nonlinear control method are evaluated by simulation and the results demonstrate the effectiveness of the proposed control strategy for the quadrotor helicopter in vertical flights.

An Analytical Design Method for Milling Cutters With Non-Constant Pitch to Increase Stability

2000 ◽  
Author(s):  
Erhan Budak
Keyword(s):  
Surface Finish ◽  
Design Method ◽  
Stability Limit ◽  
Analytical Stability ◽  
Chatter Vibrations ◽  
Constant Pitch ◽  
Improved Stability ◽  
Limited Frequency ◽  
The Stability ◽  
Explicit Relation

Abstract Chatter vibrations result in reduced productivity, poor surface finish and decreased cutting tool life. Milling cutters with non-constant pitch angles can be very effective in improving the stability of the process against chatter. In this paper, an analytical stability model and a design method are presented for non-constant pitch cutters. An explicit relation is obtained between the stability limit and the pitch variation which leads to a simple equation for optimal pitch angles. A certain pitch variation is effective for limited frequency and speed ranges which are also predicted by the model. The improved stability, productivity and surface finish are demonstrated by several examples.

scholarly journals Secure Load Frequency Control of Smart Grids under Deception Attack: A Piecewise Delay Approach

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2266 ◽  
Author(s):  
Fei Zhao ◽  
Jinsha Yuan ◽  
Ning Wang ◽  
Zhang Zhang ◽  
Helong Wen
Keyword(s):  
Smart Grids ◽  
Controller Design ◽  
Design Method ◽  
Frequency Control ◽  
Functional Method ◽  
Load Frequency Control ◽  
Linear Matrix ◽  
Load Frequency ◽  
The Stability

The problem of secure load frequency control of smart grids is investigated in this paper. The networked data transmission within the smart grid is corrupted by stochastic deception attacks. First, a unified Load frequency control model is constructed to account for both network-induced effects and deception attacks. Second, with the Lyapunov functional method, a piecewise delay analysis is conducted to study the stability of the established model, which is of less conservativeness. Third, based on the stability analysis, a controller design method is provided in terms of linear matrix inequalities. Finally, a case study is carried out to demonstrate the derived results.

scholarly journals Sensitivity Analysis of Influencing Factors of Building Slope Stability Based on Orthogonal Design and Finite Element Calculation

2018 ◽  
Vol 53 ◽  
pp. 03076
Author(s):  
RUAN Jin-kui ◽  
ZHU Wei-wei
Keyword(s):  
Finite Element ◽  
Slope Stability ◽  
Design Method ◽  
Orthogonal Design ◽  
Slope Angle ◽  
Friction Angle ◽  
Range Analysis ◽  
Factors Affecting ◽  
Orthogonal Test Design ◽  
The Stability

In order to study the sensitivity of factors affecting the homogeneous building slope stability, the orthogonal test design method and shear strength reduction finite element method were used. The stability safety factor of the slope was used as the analysis index, and the range analysis of results of 18 cases were carried out. The results show that the order of sensitivity of slope stability factors is: internal friction angle, slope height, cohesion, slope angle, bulk density, elastic modulus, Poisson's ratio. The analysis results have reference significance for the design and construction of building slope projects.

scholarly journals Study of Local and Distortional Stability of Thin-Walled Structures

2018 ◽  
Vol 149 ◽  
pp. 01089
Author(s):  
Mahi Imene ◽  
Djafour Naoual ◽  
Djafour Mustapha
Keyword(s):  
Design Method ◽  
Global Mode ◽  
Thin Walls ◽  
Thin Walled Structures ◽  
Post Buckling ◽  
Steel Sections ◽  
Resistance Curves ◽  
Thin Walled ◽  
The Stability ◽  
Hot Rolled

Thin-walled structures have an increasingly large and growing field of application in the engineering sector, the goal behind using this type of structure is efficiency in terms of resistance and cost, however the stability of its components (the thin walls) remains the first aspect of the behavior, and a primordial factor in the design process. The hot rolled sections are known by a consequent post-buckling reserve, cold-formed steel sections which are thin-walled elements also benefit, in this case, it seems essential to take into account the favorable effects of this reserve in to the verification procedure of the resistance with respect to the three modes of failures of this type of structure. The design method that takes into account this reserve of resistance is inevitably the effective width method. The direct strength method has been developed to improve the speed and efficiency of the design of thin-walled profiles. The latter mainly uses the buckling loads (for Local, Distortional and Global mode) obtained from a numerical analysis and the resistance curves calibrated experimentally to predict the ultimate load of the profile. Among those, the behavior of a set of Cshaped profiles (highly industrialized) is studied, this type of section is assumed to be very prone to modes of local and distortional instability. The outcome of this investigation revealed very relevant conclusions both scientifically and practically.

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