Damage of bearings is the most common cause of failures of squirrel-cage induction motors. A faulty bearing results in additional motor vibrations. They are reflected in the harmonic content of stator currents. In cer...
详细信息
Damage of bearings is the most common cause of failures of squirrel-cage induction motors. A faulty bearing results in additional motor vibrations. They are reflected in the harmonic content of stator currents. In certain operating conditions the current signal is the sole source of information on the state of the motor. The paper presents a mathematical model of the motor, allowing for rotor eccentricities. Calculated spectra of the stator currents are presented for the cases of operation with rotor vibrations mapping with some approximation the vibrations caused by faulty bearings. The paper presents also results of laboratory simulations for a motor put into vibrations of adjustable frequency. Vibrations of the motor housing simulate the rotor oscillations caused by a damaged bearing. The results of laboratory simulations permitted to define the relations linking vibrations of the air gap with the components in the stator current spectrum.
This paper is concerned with improvement of the KDI-based fault detection method so far developed by authors for nonlinear black-box systems. When modeling the system, Quasi-ARMAX model with multi-model structure is u...
详细信息
In this paper a novel approach to the impulsive noise removal in color images is presented. The proposed technique employs the switching scheme based on the impulse detection mechanism using the so called peer group c...
详细信息
This paper discusses a parallel genetic algorithm (GA) which focuses on the local operator for Traveling salesman problem (TSP). The local operator is a simple GA named as Local Genetic Algorithm (LGA). The LGA is com...
详细信息
This paper discusses a parallel genetic algorithm (GA) which focuses on the local operator for Traveling salesman problem (TSP). The local operator is a simple GA named as Local Genetic Algorithm (LGA). The LGA is combined to another GA named as Global Genetic Algorithm (GGA). It increases the computational time running a GA as a local operator in another one. To solve this problem, we build a parallel system based on our previous works for running the LGA to speed up the process. The results show that LGA improve the search quality significantly and it is more efficient running LGA with parallel system than single CPU.
In this paper a novel approach to the impulsive noise removal in color images is presented. The proposed technique employs the switching scheme based on the impulse detection mechanism using the so called peer group c...
详细信息
In this paper a novel approach to the impulsive noise removal in color images is presented. The proposed technique employs the switching scheme based on the impulse detection mechanism using the so called peer group concept. Compared to the vector median filter, the proposed technique consistently yields better results in suppressing both the random-valued and fixed-valued impulsive noise. The main advantage of the proposed noise detection framework is its enormous computational speed, which enables efficient filtering of large images in real-time applications.
This paper is concerned with improvement of the KDI-based fault detection method so far developed by authors for nonlinear black-box systems. When modeling the system, Quasi-ARMAX model with multi-model structure is u...
详细信息
This paper is concerned with improvement of the KDI-based fault detection method so far developed by authors for nonlinear black-box systems. When modeling the system, Quasi-ARMAX model with multi-model structure is used. A fault due to unexpected change in system parameters will appear as the change of identified model. Kullback discrimination Information (KDI) can then be used as the fault detection index to evaluate the distortion in identified model. Several schemes to improve the fault detection performance are proposed, as well as the realization of a kind of fault isolation function based on a recognition approach in the model parameter space. The effectiveness of the method is verified through simulation studies on the ship propulsion system constructed for benchmark test.
We employ set oriented methods in combination with graph partitioning algorithms to identify key dynamical regions in the Sun-Jupiter-particle three-body system. Transport rates from a region near the 3∶2 Hilda reson...
详细信息
We employ set oriented methods in combination with graph partitioning algorithms to identify key dynamical regions in the Sun-Jupiter-particle three-body system. Transport rates from a region near the 3∶2 Hilda resonance into the realm of orbits crossing Mars’ orbit are computed. In contrast to common numerical approaches, our technique does not depend on single long term simulations of the underlying model. Thus, our statistical results are particularly reliable since they are not affected by a dynamical behavior which is almost nonergodic (i.e., dominated by strongly almost invariant sets).
We will argue in this paper that the nature and magnitude of model uncertainty dictate the appropriateness of the control system design methodology. To obtain these arguments, we will pursue optimality of the control ...
详细信息
We will argue in this paper that the nature and magnitude of model uncertainty dictate the appropriateness of the control system design methodology. To obtain these arguments, we will pursue optimality of the control ...
详细信息
We will argue in this paper that the nature and magnitude of model uncertainty dictate the appropriateness of the control system design methodology. To obtain these arguments, we will pursue optimality of the control system design. Note this is a philosophical paper , in which we present our arguments in qualitative terms . We will identify the circumstances under which several control system design methodologies are appropriate. The design methodologies that will be considered are (1) optimal control and optimal feedback design, (2) model predictive control (receding horizon control), (3) active and passive adaptive control and (4) robust control. Robust control strategies are conservative and limit the possible improvements that can be obtained over say classical PID control. However, it will turn out that for certain types of control problems, improvements in performance are indeed limited. Roughly speaking, the area where we may expect (significant) improvement from advanced (optimal) control system design is very much limited by the uncertainty of the systems model. Miracles are not to be expected from advancedcontrol. What can be expected is reflected in an active adaptive optimal control scheme introduced and discussed in this paper.
The paper presents the requirements of measurement system for electric arc furnace parameters measurement and for working characteristic calculating. On this basis measurement signals were specified and measurement al...
详细信息
暂无评论