Reduction of Flow-Induced Vibration Using Parametric Excitation

2002 ◽  
Author(s):  
Tomotsugu Tanaka ◽  
Koetsu Takano ◽  
Hiroyuki Fujiwara ◽  
Osami Matsushita
Keyword(s):  
Parametric Excitation ◽  
Control Method ◽  
Excitation Frequency ◽  
Effective Control ◽  
Suspension Bridges ◽  
Control Procedure ◽  
Control Methods ◽  
Actual Structure ◽  
Excited Vibration ◽  
Experimental Apparatus

Vibration of structures, such as suspension bridges, skyscrapers and high rises, sometimes cause people to feel anxious. These vibrations are usually induced by the fluid flow, especially vortex shedding and they grow into self-excited vibrations, which are normally accompanied by the extremely large vibration amplitude. In order to solve these vibration problems, many researchers have reported the effectiveness of vibration control methods and most of the methods are very practical for the actual structure. These control methods usually consist of feedback control systems for the active control and some kinds of damper for the passive control. This paper deals with one control method, which is using the parametric excitation. The efficiencies of this method for the self-excited vibration have already been analytically examined by Tondl. However, it is not confirmed experimentally, and it is necessary to discuss the possibility of realization and application for the actual system. In this study, our experiment confirms the effectiveness of this control method. For this purpose, an experimental apparatus, which expressed a two degrees of freedom system and consisted of an electromagnetic actuator, a steel beam and two masses, were prepared. A digital signal processor was used for the realization of the parametric excitation control. During the experiments, we confirmed the effectiveness of the control procedure and accuracy of the theoretical results. In addition, the relationships between the ratio of the two masses and the ratio of the natural and the parametric excitation frequency, which are required for the effective control, were cleared. According to this study, the quenching of self-excited vibration by using the parametric excitation is realized within the very narrow band of frequency and the mass ratio should be small.

Research on Multi-Actuators Speed Control Methods in Large-Scale Vessel

2009 ◽  
Vol 419-420 ◽  
pp. 85-88
Author(s):  
Hui Xiong Wan ◽  
Hui Huang ◽  
Hai Bo Huang
Keyword(s):  
Large Scale ◽  
Control Method ◽  
Flow Distribution ◽  
Speed Control ◽  
Effective Control ◽  
Control Methods ◽  
Simulation Research ◽  
Compensation Control ◽  
Speed Error ◽  
Pressure Compensation

For multi-actuators speed control system driven by single pump, several effective control methods have been proposed, such as flow feedback control, etc. These methods are effective only to the engineering equipment with fewer actuators. As for large vessels with more than ten actuators required for speed control, using traditional control methods will result in that costs much, the structure of the hydraulic system is very complicated, even unable to realize. In order to meet the coordinate action of many actuators, two ways based on throttle control and pressure compensation control are introduced in this paper. The research results based on the theoretical analysis of speed control error and adaptability, simulation research and experimental confirmation indicate that the throttle control method is limited by the number of actuators, load size and the speed error, but the pressure compensation control method is helpful to enhance rationality and the coordination of flow distribution between various actuators.

scholarly journals Partial Frequency Assignment for Torsional Vibration Control of Complex Marine Propulsion Shafting Systems

2019 ◽  
Vol 10 (1) ◽  
pp. 147
Author(s):  
Meilong Chen ◽  
Huajiang Ouyang ◽  
Wanyou Li ◽  
Donghua Wang ◽  
Siyuan Liu
Keyword(s):  
Vibration Control ◽  
Natural Frequency ◽  
Torsional Vibration ◽  
Control Method ◽  
Excitation Frequency ◽  
Frequency Assignment ◽  
Effective Control ◽  
Partial Frequency ◽  
Structural Modifications ◽  
Ship Propulsion

With the large-scale and complexity of ship propulsion shafting, it is more difficult to analyze and control the torsional vibration of shafting. Therefore, an effective control method for the torsional vibration of shafting is of great significance in the field of ship engineering. The main strategy of torsional vibration control adopted in this paper is to keep the natural frequency of a shaft system away from the excitation frequency through structural modifications. In addition, because the basic parameters of much of the equipment in engineering applications cannot be changed, this restriction cannot be ignored when seeking solutions related to structural modifications. This paper studies the partial eigenvalue assignment for the torsional vibration control of complex ship propulsion shafting using the gradient flow method, which can shift a “dangerous” natural frequency to a safe value, while satisfying complex physical constraints. The models of a ship propulsion system and a diesel generator set are established to demonstrate several different desired modification schemes and constraint conditions in practice. In particular, close frequencies are shifted. The numerical simulation results demonstrate that it is effective and feasible to make a partial frequency assignment of torsional vibration, which provides a reliable approach for the control of torsional vibration for complex shaft systems in practical engineering.

Research on Multi-Actuators Speed Control System in Large-Scale Ship

2009 ◽  
Vol 16-19 ◽  
pp. 1138-1142
Author(s):  
Hui Xiong Wan ◽  
Hong Jie Xia ◽  
Hai Bo Huang
Keyword(s):  
Control System ◽  
Large Scale ◽  
Control Method ◽  
Flow Distribution ◽  
Speed Control ◽  
Effective Control ◽  
Control Methods ◽  
Compensation Control ◽  
Speed Control System ◽  
Pressure Compensation

For multi-actuators speed control system driven by single pump, several effective control methods have been proposed, such as flow feedback control, etc. These methods are effective only to the engineering equipment with fewer actuators. As for large ships with more than ten actuators required for speed control, using traditional control methods will result in that costs much, the structure of the hydraulic system is very complicated, even unable to realize. In order to meet the coordinate action of many actuators, two ways based on throttle control and pressure compensation control are introduced in this paper. The research results based on the theoretical analysis of speed control error and adaptability, simulation research and experimental confirmation indicate that the throttle control method is limited by the number of actuators, load size and the speed error, but the pressure compensation control method is helpful to enhance rationality and the coordination of flow distribution between various actuators.

Rapid identification of Erwinia amylovora and Pseudomonas syringae species and characterization of E. amylovora streptomycin resistance using quantitative PCR assays

2019 ◽  
Vol 65 (7) ◽  
pp. 496-509 ◽  
Author(s):  
Martin Laforest ◽  
Katherine Bisaillon ◽  
Marie Ciotola ◽  
Mélanie Cadieux ◽  
Pierre-Olivier Hébert ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Erwinia Amylovora ◽  
Control Method ◽  
Fruit Production ◽  
Effective Control ◽  
Control Methods ◽  
Bacterial Isolates ◽  
Pome Fruit ◽  
Molecular Tests

Erwinia amylovora and Pseudomonas syringae are bacterial phytopathogens responsible for considerable yield losses in commercial pome fruit production. The pathogens, if left untreated, can compromise tree health and economically impact entire commercial fruit productions. Historically, the choice of effective control methods has been limited. The use of antibiotics was proposed as an effective control method. The identification of these pathogens and screening for the presence of antibiotic resistance is paramount in the adoption and implementation of disease control methods. Molecular tests have been developed and accepted for identification and characterization of these disease-causing organisms. We improved existing molecular tests by developing methods that are equal or superior in robustness for identifying E. amylovora or P. syringae while being faster to execute. In addition, the real-time PCR-based detection method for E. amylovora provided complementary information on the susceptibility or resistance to streptomycin of individual isolates. Finally, we describe a methodology and results that compare the aggressiveness of the different bacterial isolates on four apple cultivars. We show that bacterial isolates exhibit different behaviors when brought into contact with various apple varieties and that the hierarchical clustering of symptom severity indicates a population structure, suggesting a genetic basis for host cultivar specificity.

Research and Simulation of ABS Control Method

2015 ◽  
Vol 733 ◽  
pp. 749-753 ◽  
Author(s):  
Wei Zhang ◽  
Guan Neng Xu ◽  
Xue Xun Guo ◽  
Wen Zhang
Keyword(s):  
Fuzzy Control ◽  
Pid Control ◽  
Control Method ◽  
Point Of View ◽  
Effective Control ◽  
Control Methods ◽  
Slip Ratio ◽  
Ratio Curve ◽  
Braking Distance ◽  
Set Up

Based on the ABS model of a single wheel system, the traditional logic threshold, PID and fuzzy control method have been used to study the control system of commercial vehicle’s ABS. As the most important task of commercial vehicle’s ABS is to prevent the two front (steering) wheels from locking, the slip ratio should be controlled strictly in the safe range. A very short time of locking may cause the failure of steering, so control method which can keep slip ratio in the secure scope accurately can help vehicle avoid the danger of runaway. Set up the model on Simulink platform. Then, use the three control methods to control the ABS. By comparing and analyzing the processes and results under the control methods, find an appropriate way that can provide the most secure and effective control. From the perspective of processes (slip ratio changes), the simulations under the three control methods show the PID control gives the best slip ratio curve. The curve is almost coinciding with the ideal slip ratio curve. The oscillation of slip ratio given by fuzzy control is the most sever. From the point of view of the results (braking distance), the braking system with PID control has the shortest braking distance while with the fuzzy control has the longest. That is not to say fuzzy control is not advanced but the actual experiences difficult to get. And with the long response time, the fuzzy control is not suitable for commercial vehicle’s ABS. As a result and with the development and decreasing cost of PID controller, it is competitive in today’s ABS market.

Exploration on Shape of Profiles Determined by Chord Angle Control Method

2011 ◽  
Vol 314-316 ◽  
pp. 837-841
Author(s):  
Ling Ling ◽  
Yuan Sheng Zeng
Keyword(s):  
Theoretical Basis ◽  
Control Method ◽  
Angle Measurement ◽  
Mapping Method ◽  
Control Methods ◽  
Forming Process ◽  
Spline Curve ◽  
Curve Line ◽  
Line Measure

Through compassion of relative merits of the existing two control methods of straighten anti-curve line and chord line measure for cold-formed profiles, a three-pivot chord angle control method of non-endpoint measurement was proposed in this paper, and its feasibility was proved by using mathematical deduction. Using mapping method, the forming of profiles can be controlled by the only one set of orderly array chord angles and chord lines obtained by a spline curve of profiles, and meanwhile, the length of automation feedstock in forming process of profiles was explored. The present research achievements can provide a good theoretical basis for the further application on controlling profile forming with the chord angle measurement.

scholarly journals A Review of Alternative Management Tactics Employed for the Control of Various Cockroach Species (Order: Blattodea) in the USA

Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 550
Author(s):  
Ameya D. Gondhalekar ◽  
Arthur G. Appel ◽  
Gretchen M. Thomas ◽  
Alvaro Romero
Keyword(s):  
Applied Research ◽  
Research Effort ◽  
Effective Control ◽  
Control Methods ◽  
Alternative Tactics ◽  
Alternative Control ◽  
The Public ◽  
Concurrent Use ◽  
The Usa ◽  
Alternative Control Methods

Effective control of domestic and peridomestic cockroaches requires integrated approaches that emphasize concurrent use of chemicals with alternative control tactics. An integrated pest management (IPM) approach is particularly justified in environments where satisfactory cockroach control cannot be achieved due to multiple factors including development of insecticide aversion and resistance in some cockroach species, and poor sanitation or structural issues that foster infestations. While a flurry of research effort has been devoted to study alternative tactics for cockroach control, only a few of them have been evaluated in the context of IPM programs. This review focuses on examining studies on alternative tactics that are proven efficacious, economical, and logistically feasible for their inclusion in IPM programs for important domestic and peridomestic cockroaches in the USA. Management programs that educate the public on cockroach biology, behavior, and the importance of sanitation; use of traps to monitor infestation levels; apply targeted low impact insecticides such as baits, have demonstrated a greater success for effective and sustainable control of cockroaches when compared to an insecticide-only approach. Incorporation of other alternative control methods to IPM programs will require more applied research that validates their use in real-world scenarios and demonstrates their cost-effectiveness.

scholarly journals A New Model Predictive Control Method for Eliminating Hydraulic Oscillation and Dynamic Hydraulic Imbalance in a Complex Chilled Water System

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3608
Author(s):  
Yang Yuan ◽  
Neng Zhu ◽  
Haizhu Zhou ◽  
Hai Wang
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Control Method ◽  
Water System ◽  
Energy Performance ◽  
Effective Control ◽  
New Model ◽  
Chilled Water ◽  
Chilled Water System ◽  
Hydraulic Oscillation

To enhance the energy performance of a central air-conditioning system, an effective control method for the chilled water system is always essential. However, it is a real challenge to distribute exact cooling energy to multiple terminal units in different floors via a complex chilled water network. To mitigate hydraulic imbalance in a complex chilled water system, many throttle valves and variable-speed pumps are installed, which are usually regulated by PID-based controllers. Due to the severe hydraulic coupling among the valves and pumps, the hydraulic oscillation phenomena often occur while using those feedback-based controllers. Based on a data-calibrated water distribution model which can accurately predict the hydraulic behaviors of a chilled water system, a new Model Predictive Control (MPC) method is proposed in this study. The proposed method is validated by a real-life chilled water system in a 22-floor hotel. By the proposed method, the valves and pumps can be regulated safely without any hydraulic oscillations. Simultaneously, the hydraulic imbalance among different floors is also eliminated, which can save 23.3% electricity consumption of the pumps.

scholarly journals Emulation of grid-forming inverters using real-time PC and 4-quadrant voltage amplifier

2021 ◽  
Author(s):  
Wolf Schulze ◽  
Maurizio Zajadatz ◽  
Michael Suriyah ◽  
Thomas Leibfried
Keyword(s):  
Real Time ◽  
Control Method ◽  
Current Control ◽  
Control Methods ◽  
Test Bed ◽  
Test Scenario ◽  
Power Semiconductors ◽  
Voltage Amplifier ◽  
Grid Side ◽  
Virtual Synchronous Machine

AbstractA test bed for the evaluation of novel control methods of inverters for renewable power generation is presented. The behavior of grid-following and grid-forming control in a test scenario is studied and compared.Using a real-time capable control platform with a cycle time of 50 µs, control methods developed with Matlab/Simulink can be implemented. For simplicity, a three-phase 4‑quadrant voltage amplifier is used instead of an inverter. Thus, the use of modulation and switched power semiconductors can be avoided. In order to show a realistic behavior of a grid-side filter, passive components can be automatically connected as L‑, LC- or LCL-filter. The test bed has a nominal active power of 43.6 kW and a nominal voltage of 400 V.As state-of-the-art grid-following control method, a current control in the d/q-system is implemented in the test bed. A virtual synchronous machine, the Synchronverter, is used as grid-forming control method. In combination with a frequency-variable grid emulation, the behavior of both control methods is studied in the event of a load connection in an island grid environment.

A compliant control method for disassembly of non-elastic parts using realised motion

Robotica ◽  
1995 ◽  
Vol 13 (6) ◽  
pp. 591-598 ◽  
Author(s):  
Yagmur Denizhan
Keyword(s):  
Control Method ◽  
Recognition System ◽  
Automatic Recognition ◽  
Human Operator ◽  
Control Methods ◽  
Compliant Control ◽  
On Line

SummaryIn disassembly tasks, due to the large variety of objects and the different positions and orientations in which they appear, the disassembly trajectories supplied on-line by a human operator or an automatic recognition system can contain large errors. The classical compliant control methods turn out to be insufficient to eliminate sticking which is due to these errors. This paper presents a compliant control method for disassembly of non-elastic parts in non-elastic environments which adopts the trajectories according to realised motion. In case of sticking a new direction of motion is searched for until the manipulated part is set into motion.

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