scholarly journals A Critical Review of Stall Control Techniques in Industrial Fans

2013 ◽  
Vol 2013 ◽  
pp. 1-18 ◽  
Author(s):  
Stefano Bianchi ◽  
Alessandro Corsini ◽  
Anthony G. Sheard ◽  
Cecilia Tortora
Keyword(s):  
Control Systems ◽  
Passive Control ◽  
Control Strategies ◽  
Warning System ◽  
Detection Methods ◽  
Stall Inception ◽  
Stall Margin ◽  
Control Techniques ◽  
Control Technologies ◽  
And Control

This paper reviews modelling and interpretation advances of industrial fan stall phenomena, related stall detection methods, and control technologies. Competing theories have helped engineers refine fan stability and control technology. With the development of these theories, three major issues have emerged. In this paper, we first consider the interplay between aerodynamic perturbations and instability inception. An understanding of the key physical phenomena that occurs with stall inception is critical to alleviate stall by design or through active or passive control methods. We then review the use of passive and active control strategies to improve fan stability. Whilst historically compressor design engineers have used passive control techniques, recent technologies have prompted them to install high-response stall detection and control systems that provide industrial fan designers with new insight into how they may detect and control stall. Finally, the paper reviews the methods and prospects for early stall detection to complement control systems with a warning capability. Engineers may use an effective real-time stall warning system to extend a fan’s operating range by allowing it to operate safely at a reduced stall margin. This may also enable the fan to operate in service at a more efficient point on its characteristic.

A Comprehensive Review on Reconfigurable Drones: Classification, Characteristics, Design and Control Technologies

2021 ◽  
pp. 1-27
Author(s):  
Saddam Hocine Derrouaoui ◽  
Yasser Bouzid ◽  
Mohamed Guiatni ◽  
Islam Dib
Keyword(s):  
Fault Tolerant ◽  
Control Strategies ◽  
Cluttered Environments ◽  
Viable Solution ◽  
Promising Solution ◽  
Design Characteristics ◽  
And Performance ◽  
Control Technologies ◽  
And Control ◽  
Near Future

Recently, reconfigurable drones have gained particular attention in the field of automation and flying robots. Unlike the conventional drones, they are characterized by a variable mechanical structure in flight, geometric adaptability, aerial reconfiguration, high number of actuators and control inputs, and variable mathematical model. In addition, they are exploited to flight in more cluttered environments, avoid collisions with obstacles, transport and grab objects, cross narrow and small spaces, decrease different aerial damages, optimize the consumed energy, and improve agility and maneuverability in flight. Moreover, these new drones are considered as a viable solution to provide them with specific and additional functionalities. They are a promising solution in the near future, since they allow increasing considerably the capabilities and performance of classical drones in terms of multi-functionalities, geometric adaptation, design characteristics, consumed energy, control, maneuverability, agility, efficiency, obstacles avoidance, and fault tolerant control. This paper explores very interesting and recent research works, which include the classification, the main characteristics, the various applications, and the existing designs of this particular class of drones. Besides, an in-depth review of the applied control strategies will be presented. The links of the videos displaying the results of these researches will be also shown. A comparative study between the different types of flying vehicles will be established. Finally, several new challenges and future directions for reconfigurable drones will be discussed.

scholarly journals An Assessment Model for Rating High-Threat Crop Pathogens

2006 ◽  
Vol 96 (6) ◽  
pp. 616-621 ◽  
Author(s):  
N. W. Schaad ◽  
J. Abrams ◽  
L. V. Madden ◽  
R. D. Frederick ◽  
D. G. Luster ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Control Strategies ◽  
Threat Assessment ◽  
The United States ◽  
Assessment Model ◽  
Detection Methods ◽  
Analytic Hierarchy ◽  
Rating Model ◽  
And Control ◽  
High Threat

Natural, accidental, and deliberate introductions of nonindigenous crop pathogens have become increasingly recognized as threats to the U.S. economy. Given the large number of pathogens that could be introduced, development of rapid detection methods and control strategies for every potential agent would be extremely difficult and costly. Thus, to ensure the most effective direction of resources a list of high-threat pathogens is needed. We address development of a pathogen threat assessment model based on the analytic hierarchy process (AHP) that can be applied world-wide, using the United States as an illustrative example. Previously, the AHP has been shown to work well for strategic planning and risk assessment. Using the collective knowledge of subject matter expert panels incorporated into commercial decision-making software, 17 biological and economic criteria were determined and given weights for assessing the threat of accidental or deliberately introduced pathogens. The rating model can be applied by experts on particular crops to develop threat lists, especially those of high priority, based on the current knowledge of individual diseases.

Detection Method and Control Strategy of Active Power for Wind Farm Connected into Grid

2013 ◽  
Vol 380-384 ◽  
pp. 2962-2966
Author(s):  
Chun Guang Tian ◽  
De Xin Li ◽  
Li Xia Cai ◽  
Tian Dong ◽  
Xiao Juan Han
Keyword(s):  
Control Strategy ◽  
Wind Farm ◽  
Detection Method ◽  
Control Strategies ◽  
Active Power ◽  
Detection Methods ◽  
Grid System ◽  
Simulation Results ◽  
And Control ◽  
Huge Challenge

As one of main clean energies, wind power has been developed fast, but the fluctuations of active power at a wind farm is a huge challenge for the grid system, thus it is essential for wind farm connected into grid to detection the active power. This paper studied control strategies and detection methods of the active power at a wind farm. Simulation results showed the effective detection of active power at a wind farm can improve the characteristics of the grid and the ability of wind farm to regulate the grid and increase the scheduled ability of wind farm.

scholarly journals Recent Advances in Bidirectional Modeling and Structural Control

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Satyam Paul ◽  
Wen Yu ◽  
Xiaoou Li
Keyword(s):  
Control Systems ◽  
Structural Control ◽  
Seismic Waves ◽  
Control Strategies ◽  
Optimal Placement ◽  
Modeling And Control ◽  
Control Devices ◽  
Identification Techniques ◽  
And Control ◽  
Bidirectional Modeling

This paper provides an overview of building structure modeling and control under bidirectional seismic waves. It focuses on different types of bidirectional control devices, control strategies, and bidirectional sensors used in structural control systems. This paper also highlights the various issues like system identification techniques, the time-delay in the system, estimation of velocity and position from acceleration signals, and optimal placement of the sensors and control devices. The importance of control devices and its applications to minimize bidirectional vibrations has been illustrated. Finally, the applications of structural control systems in real buildings and their performance have been reviewed.

scholarly journals Nonlinear control of GTI for stabilizing future smart grids

2020 ◽  
Vol 11 (3) ◽  
pp. 1268
Author(s):  
Salam Ibrahim Khather
Keyword(s):  
Control Systems ◽  
Distributed Generation ◽  
Smart Grids ◽  
High Performance ◽  
Low Cost ◽  
Control Parameters ◽  
Leakage Currents ◽  
Control Techniques ◽  
Control Scheme ◽  
And Control

The most important components of the distributed generation frameworks is the GTIs which is an interface amidst the utility and the source of energy. The recent years have seen an increased interest in the design and usage of GTIs due to its smaller weight and size, low cost and higher efficiency. But the problem of leakage currents in the transformerless inverter that is dependant on its topology and control scheme needs to be looked into carefully. Also, the high performance of the GTI requires a stringent control and various control systems are being developed and applied to the GTIs. This paper reviews the various topologies that are classified based on the attributes of the leakage current and the method of decoupling. Further it reviews and compares the different control techniques applied to the GTIs with respect to the frame of reference, controller, modulation technique and the control parameters considered.

When are Nonlinearities Important at Stall Inception?

1994 ◽  
Author(s):  
F. E. McCaughan
Keyword(s):  
Three Dimensional ◽  
Numerical Data ◽  
Nonlinear Effects ◽  
Sine Wave ◽  
Rotating Stall ◽  
Stall Inception ◽  
Stall Margin ◽  
Compression System ◽  
And Control ◽  
Recent Experimental Work

Recent experimental work has shown that in some compressors, the nonaxisymmetric disturbance leading to loss of stability appears as a localised phenomena, rather than a travelling sine wave which spans the entire circumference, suggesting that nonlinear effects appear very early in the evolution of the disturbance. In a regime dominated by nonlinear effects, the Fourier modes used to describe the spatial structure of non-axisymmetric disturbances, obtained from either experimental data or numerical data produced by a model, can interact very early in the rotating stall inception process. In this paper, we determine which parameters affect the rate of interaction of the various modes in a study of the Moore-Greitzer (MG) model. The relevant parameters are related back to the physics of compressors. Though the stall inception process may well be three-dimensional and involve physics not captured by the quasi two dimensional MG model, this study is of interest to those who wish to detect and control the magnitude of nonaxisymmetric disturbances, in order to decrease the stall margin in a compression system. Any control strategy which depends on eight detecting devices around the annulus of the compressor can resolve only the first three spatial Fourier modes. If disturbances leading to compression system instability develop as spikes, this approach will be completely unsuccessful at detecting the disturbances while they are still small enough to be controlled. The problem is further exacerbated by temporal nonlinearities, that is, the operating point may be linearly stable, but may lose stability to larger disturbances. It is observed in experiments and the Moore-Greitzer model that the compressor loses stability before the throttle is closed past the peak of the performance curve. Both spatial and temporal nonlinearities are discussed.

scholarly journals Experimental sensitivity analysis and control of thermoacoustic systems

2015 ◽  
Vol 787 ◽  
Author(s):  
Georgios Rigas ◽  
Nicholas P. Jamieson ◽  
Larry K. B. Li ◽  
Matthew P. Juniper
Keyword(s):  
Growth Rate ◽  
Sensitivity Analysis ◽  
Passive Control ◽  
Control Strategies ◽  
Control Device ◽  
Linear Regime ◽  
Adjoint Methods ◽  
Rijke Tube ◽  
Theoretical Predictions ◽  
And Control

In this paper, we report the results of an experimental sensitivity analysis on a thermoacoustic system – an electrically heated Rijke tube. We measure the change of the linear stability characteristics of the system, quantified as shifts in the growth rate and oscillation frequency, that is caused by the introduction of a passive control device. The control device is a mesh, which causes drag in the system. The rate of growth is slow, so the growth rate and frequency can be measured very accurately over many hundreds of cycles in the linear regime with and without control. These measurements agree qualitatively well with the theoretical predictions from adjoint-based methods of Magri & Juniper (J. Fluid Mech., vol. 719, 2013, pp. 183–202). This agreement supports the use of adjoint methods for the development and implementation of control strategies for more complex thermoacoustic systems.

scholarly journals Prevalence, determination, and control of histamine formation in food concerning food safety aspect

2021 ◽  
Vol 13 (2) ◽  
pp. 101-117
Author(s):  
Chuyen Hoang ◽  
Thi-Van Nguyen ◽  
Thanh Do Le
Keyword(s):  
Control Strategies ◽  
Food Poisoning ◽  
Food Sources ◽  
Detection Methods ◽  
Fermented Foods ◽  
Toxic Metabolite ◽  
Detection Techniques ◽  
Histamine Formation ◽  
High Level ◽  
And Control

Histamine is a toxic metabolite produced in foods containing a high level of free histidine. This compound can be present in various food sources, especially seafood, dairy products, and fermented foods. Histamine poisoning is one of the most common health risks caused by consuming spoiled foods or improper processed and stored foods. This food poisoning usually causes mild symptoms with higher recovery rates, so people underestimate this hazard. Thus, understanding histamine formation food sources with a high risk for this poisonous agent is critical in improving the awareness of this hazard for food producers and consumers. To avoid histamine-associated food poisoning, the development of control solutions to minimize the formation of histamine and the sufficient detection methods to examine the content of this metabolite in food products are vital. In addition to quality control application and hazards management programs in food processing, the appropriate food regulations identifying the precise limit of histamine in foods are essential for preventing this poisoning from occurring in the food supply chain. This review discusses the prevalence, control strategies, detection techniques, and regulations related to histamine hazards in foods.

Beverage spoilage yeast detection methods and control technologies: A review of Brettanomyces

2018 ◽  
Vol 283 ◽  
pp. 65-76 ◽  
Author(s):  
Imanol Tubia ◽  
Karthik Prasad ◽  
Eva Pérez-Lorenzo ◽  
Cristina Abadín ◽  
Miren Zumárraga ◽  
...  
Keyword(s):  
Detection Methods ◽  
Spoilage Yeast ◽  
Control Technologies ◽  
And Control

scholarly journals A New Finance Chaotic System, its Electronic Circuit Realization, Passivity based Synchronization and an Application to Voice Encryption

2019 ◽  
Vol 8 (1) ◽  
pp. 193-205 ◽  
Author(s):  
Sundarapandian Vaidyanathan ◽  
Aceng Sambas ◽  
Sezgin Kacar ◽  
Unal Cavusoglu
Keyword(s):  
Passive Control ◽  
Algorithm Design ◽  
Chaotic Circuit ◽  
Circuit Realization ◽  
Control Techniques ◽  
Investment Demand ◽  
Chaotic Model ◽  
Finance Model ◽  
The Interest Rate ◽  
And Control

Abstract Modelling and control applications of dynamical systems in chaos theory arising in several areas are investigated and new control techniques are designed in the chaos literature. We propose a new complex finance chaotic model with states as the interest rate, investment demand, and price index. In this work, after studying the dynamical properties of the new finance model, an electronic chaotic circuit of the model is realized in Multisim. Based on passive control theory, we derive a new controller for globally synchronizing state trajectories of the new finance models. Using the new finance chaotic model developed in this work, a new voice encryption algorithm design is presented. With the proposed algorithm, voice encryption application is performed, and results are described.

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