scholarly journals Narrowband Control Design for Smart Structural Systems

2001 ◽  
Author(s):  
Daniel J. Kolepp ◽  
Ralph C. Smith
Keyword(s):  
Discrete System ◽  
Natural Frequencies ◽  
Control Method ◽  
Control Strategies ◽  
Control Design ◽  
Structural Systems ◽  
Pde Model ◽  
Finite Dimensional ◽  
Initial Control ◽  
Physical Attributes

Abstract This investigation focuses on the development of narrowband control strategies which are effective for structural systems subjected to both harmonic exogenous forces and stochastic uncertainties in the model or measurements. A cantilever beam with surface-mounted piezoceramic actuators is used as a prototypical structure since it exhibits physical attributes of a variety of vibrating structures but is sufficiently simple to facilitate initial control design. A PDE model for the structure is discretized using a spline-based Galerkin technique to obtain a semi-discrete system that is appropriate for finite-dimensional control design. A narrowband control method, which can be tuned to attenuate either natural frequencies or specific frequencies in the exogenous input, is developed and compared with standard LQR techniques through numerical examples.

Infections of bean plant and field soil are linked to region, root rot pathogen, and agro-ecosystem

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
B. Naseri ◽  
M. Gheitury ◽  
M. Veisi
Keyword(s):  
Root Rot ◽  
Multivariate Analyses ◽  
Control Method ◽  
Control Strategies ◽  
Fusarium Species ◽  
Macrophomina Phaseolina ◽  
Soil Variables ◽  
Plant Infection ◽  
Pathogen Prevalence ◽  
Soil Infestation

SummaryUnderstanding pathogen-agrosystem interaction is particularly essential when applying a control method to minimize pathogen prevalence prior to plant infection. To meet this requirement, frequency of major root rot pathogens isolated from bean root and seed, and their soil populations were examined in farmers’ fields. Multivariate analyses evidenced more frequent isolations of Fusarium solani and Rhizoctonia solani from root and seed compared to Macrophomina phaseolina and Fusarium oxysporum. Two Fusarium species had denser soil populations than R. solani and M. phaseolina. More frequent isolations of pathogens were detected in root and seed collected from Abhar and Khodabandeh compared to Kheirabad region. Agronomic and soil variables corresponded less closely to root infections compared to soil infestation and seed infections. Bean market class, herbicide application, and planting depth were linked to root, seed and soil infestations. Such information provides a basis for increased confidence in choosing appropriate control strategies for a pathogen and region in sustainable agriculture.

Improved Oxygen Dissolution Control for Oxygen Activated Sludge

1988 ◽  
Vol 20 (4-5) ◽  
pp. 101-108 ◽  
Author(s):  
R. C. Clifft ◽  
M. T. Garrett
Keyword(s):  
Activated Sludge ◽  
Control Method ◽  
Control Strategies ◽  
Cost Savings ◽  
Utilization Efficiency ◽  
Oxygen Production ◽  
Oxygen Utilization ◽  
Potential Cost ◽  
Oxygen Dissolution ◽  
The City

Now that oxygen production facilities can be controlled to match the requirements of the dissolution system, improved oxygen dissolution control can result in significant cost savings for oxygen activated sludge plants. This paper examines the potential cost savings of the vacuum exhaust control (VEC) strategy for the City of Houston, Texas 69th Street Treatment Complex. The VEC strategy involves operating a closed-tank reactor slightly below atmospheric pressure and using an exhaust apparatus to remove gas from the last stage of the reactor. Computer simulations for one carbonaceous reactor at the 69th Street Complex are presented for the VEC and conventional control strategies. At 80% of design loading the VEC strategy was found to provide an oxygen utilization efficiency of 94.9% as compared to 77.0% for the conventional control method. At design capacity the oxygen utilization efficiency for VEC and conventional control was found to be 92.3% and 79.5%, respectively. Based on the expected turn-down capability of Houston's oxygen production faciilities, the simulations indicate that the VEC strategy will more than double the possible cost savings of the conventional control method.

scholarly journals A Variable Parameter Ambient Vibration Control Method Based on Quasi-Zero Stiffness in Robotic Drilling Systems

Machines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 67
Author(s):  
Laixi Zhang ◽  
Chenming Zhao ◽  
Feng Qian ◽  
Jaspreet Singh Dhupia ◽  
Mingliang Wu
Keyword(s):  
Vibration Control ◽  
Vibration Isolation ◽  
Control Method ◽  
Control Strategies ◽  
Equations Of Motion ◽  
Variable Parameter ◽  
Harmonic Balance Method ◽  
Variable Stiffness ◽  
Ambient Vibration ◽  
Robotic Drilling

Vibrations in the aircraft assembly building will affect the precision of the robotic drilling system. A variable stiffness and damping semiactive vibration control mechanism with quasi-zero stiffness characteristics is developed. The quasi-zero stiffness of the mechanism is realized by the parallel connection of four vertically arranged bearing springs and two symmetrical horizontally arranged negative stiffness elements. Firstly, the quasi-zero stiffness parameters of the mechanism at the static equilibrium position are obtained through analysis. Secondly, the harmonic balance method is used to deal with the differential equations of motion. The effects of every parameter on the displacement transmissibility are analyzed, and the variable parameter control strategies are proposed. Finally, the system responses of the passive and semiactive vibration isolation mechanisms to the segmental variable frequency excitations are compared through virtual prototype experiments. The results show that the frequency range of vibration isolation is widened, and the stability of the vibration control system is effectively improved without resonance through the semiactive vibration control method. It is of innovative significance for ambient vibration control in robotic drilling systems.

Application of Combined Feedforward and Feedback Controller With Shaped Input to Benchmark Problem

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Young Joo Shin ◽  
Peter H. Meckl
Keyword(s):  
Feedback Control ◽  
Control Strategy ◽  
Control Strategies ◽  
Control Design ◽  
Single Frequency ◽  
Benchmark Problems ◽  
Control Force ◽  
Benchmark Problem ◽  
Advantages And Disadvantages ◽  
Robust Control Design

Benchmark problems have been used to evaluate the performance of a variety of robust control design methodologies by many control engineers over the past 2 decades. A benchmark is a simple but meaningful problem to highlight the advantages and disadvantages of different control strategies. This paper verifies the performance of a new control strategy, which is called combined feedforward and feedback control with shaped input (CFFS), through a benchmark problem applied to a two-mass-spring system. CFFS, which consists of feedback and feedforward controllers and shaped input, can achieve high performance with a simple controller design. This control strategy has several unique characteristics. First, the shaped input is designed to extract energy from the flexible modes, which means that a simpler feedback control design based on a rigid-body model can be used. In addition, only a single frequency must be attenuated to reduce residual vibration of both masses. Second, only the dynamics between control force and the first mass need to be considered in designing both feedback and feedforward controllers. The proposed control strategy is applied to a benchmark problem and its performance is compared with that obtained using two alternative control strategies.

scholarly journals An integrodifferential approach to modeling, control, state estimation and optimization for heat transfer systems

2016 ◽  
Vol 26 (1) ◽  
pp. 15-30 ◽  
Author(s):  
Andreas Rauh ◽  
Luise Senkel ◽  
Harald Aschemann ◽  
Vasily V. Saurin ◽  
Georgy V. Kostin
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Control Strategies ◽  
Open Loop ◽  
Distributed Parameter ◽  
Dimensional System ◽  
State Equations ◽  
Large Space ◽  
Finite Dimensional ◽  
Spatially Distributed

Abstract In this paper, control-oriented modeling approaches are presented for distributed parameter systems. These systems, which are in the focus of this contribution, are assumed to be described by suitable partial differential equations. They arise naturally during the modeling of dynamic heat transfer processes. The presented approaches aim at developing finite-dimensional system descriptions for the design of various open-loop, closed-loop, and optimal control strategies as well as state, disturbance, and parameter estimation techniques. Here, the modeling is based on the method of integrodifferential relations, which can be employed to determine accurate, finite-dimensional sets of state equations by using projection techniques. These lead to a finite element representation of the distributed parameter system. Where applicable, these finite element models are combined with finite volume representations to describe storage variables that are—with good accuracy—homogeneous over sufficiently large space domains. The advantage of this combination is keeping the computational complexity as low as possible. Under these prerequisites, real-time applicable control algorithms are derived and validated via simulation and experiment for a laboratory-scale heat transfer system at the Chair of Mechatronics at the University of Rostock. This benchmark system consists of a metallic rod that is equipped with a finite number of Peltier elements which are used either as distributed control inputs, allowing active cooling and heating, or as spatially distributed disturbance inputs.

scholarly journals From towers to walls: Trump’s border wall as entrepreneurial performance

2021 ◽  
pp. 239965442110030
Author(s):  
Åshild Kolås ◽  
Lacin ldil Oztig
Keyword(s):  
Control Strategies ◽  
Family Separation ◽  
Deferred Action ◽  
Strong Focus ◽  
Mexico Border ◽  
Physical Attributes ◽  
Southern Border ◽  
Personal Skills ◽  
Presidential Election Campaign

The pledge to build a “great”, “beautiful” southern border wall was a cornerstone of Donald J. Trump’s 2016 presidential election campaign. This paper analyzes Trump’s border wall project as an example of performative statecraft, suggesting that the wall works better rhetorically, than as a barrier against unauthorized cross-border movement. Identifying Trump’s performative statecraft as “entrepreneurial”, we argue that his border wall discourse differs from that of earlier presidents in the way Trump meshes the performance of the border wall as a protective device with his own performance as an entrepreneur and developer. Trump’s border wall discourse accentuates his personal skills as an entrepreneur, and makes these skills relevant to his key campaign promises: to “Make America Great Again”, and defend the nation against transnational crime. Despite Trump’s radical reformulation of US asylum policy, enhanced pursuit of unauthorized immigrants, termination of Obama-era programs like Deferred Action for Childhood Arrivals (DACA), and disturbing but short-lived family separation and ‘Zero-Tolerance’ detention scheme, the border security policies of President Trump are not as novel as his promotional campaigns would have us believe. In fact, Trump’s border control strategies have continued many of the measures introduced by earlier presidents. The novelty of the Trump presidency lies in the strong focus on the new US–Mexico border wall, and fervent attention to the physical attributes and instrumental functions of the wall. Much more than a fence, Trump’s proposed border wall is a grand, awe-inspiring monument to national security, and to Trump’s entrepreneurial statecraft. It also works as a visual aide for Trump’s plan to “Make America Great Again”. Border walls stand as testimony to the power of the state, and the determination of those who defend it. Trump’s border wall would be no exception.

The Investigation of the Optimization Scheme of the Low-cycle Fatigue Cropping Based on the Acoustic Emission Technique

2021 ◽  
Author(s):  
Yujian Ren ◽  
Jingxiang Li ◽  
Yuanzhe Dong ◽  
Dong Jin ◽  
Shengdun Zhao
Keyword(s):  
Acoustic Emission ◽  
High Frequency ◽  
Control Method ◽  
Low Cycle Fatigue ◽  
Control Strategies ◽  
Low Frequency ◽  
Loading Frequency ◽  
Cycle Fatigue ◽  
Al 6061 ◽  
Whole Process

Abstract High efficiency and good section quality are two main objectives of metal bar cropping. A suitable control method can help to achieve both goals. An investigation of the control method of low-cycle fatigue cropping (LCFC) based on the acoustic emission (AE) technique has been proposed in this study. Ring-down counts and kurtosis are used to monitor the whole process of LCFC. The results showed that kurtosis is more suitable for monitoring the LCFC process and as a critical parameter to optimize the control method than ring-down counts in the noisy factory environment.Moreover, three types of materials are studied in this experiment; by combine with the AE results, macroscopic images and microscopic images of sections, characteristics of various LCFC stages are obtained. The results also indicated reduce the area of the transient fracture zone is the key to improve the section quality. Reducing the load frequency before the unstable crack propagation stage will beneficial to realize the goals. Based on the evaluation of kurtosis, an optimized control method is presented, and two control parameters: transient time T and the critical value of the slope of kurtosis C are determined. For 16Mn, 1045 and Al 6061, the T is 5s, 10s, and 1s, respectively. For 16Mn, 1045, and Al 6061, the C is 100, 300, and 0, respectively. Two parameters, h and S, are used to evaluate the section quality and four control strategies are compared. The results indicate the optimal control methods can improve the section quality effectively. The influence trend of reducing loading frequency is investigated by further comparison. It can be seen as the frequency decreases, the efficiency of the section quality improving decreases. In order to realize the optimal results, different control strategies are adopted for different materials. Strategy 1 (high frequency is 20Hz，high frequency thought the whole process), strategy 2 (high frequency is 20Hz，low frequency is 8.33Hz), and strategy 3 (high frequency is 20Hz，low frequency is 6.67Hz) is suitable for Al 6061, 1045, and 16Mn, respectively.

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