Biotechnological processes are notoriously difficult to control using conventional methods owing to their time-variant and non-linear characteristics. An alternative control method is to utilise artificial intelligenc...
详细信息
Biotechnological processes are notoriously difficult to control using conventional methods owing to their time-variant and non-linear characteristics. An alternative control method is to utilise artificial intelligence such as fuzzy logic. A problem with the development of fuzzy logic controllers is rule-base generation. A Self-Learning Fuzzy Logic control (SLFLC) methodology offers a possible alternative solution. A study is presented illustrating the performance of a SLFLC by demonstrating its ability to generate a rule-set based on a predetermined criteria. The SLFLC described has been successfully applied to simulations of a Bakers Yeast fed-batch fermentation. Results demonstrate how the learning mechanism produces a rule-set which controls the dissolved oxygen concentration throughout the fermentation process duration.
We numerically study the time evolution of coherent vortices in decaying turbulence described by the Charney-Hasegawa-Mima equation with the weak dissipation. Self-organized coherent vortices develop through the mutua...
We numerically study the time evolution of coherent vortices in decaying turbulence described by the Charney-Hasegawa-Mima equation with the weak dissipation. Self-organized coherent vortices develop through the mutual advection and the vortex merging. The dimensional analysis provides the dynamical scaling law of structure function of the potential vorticity field S(k,t)=E5/4λ1/2t1/2G(k/k¯(t)) [k¯(t)∼E−1/8λ3/4t−1/4] with a scaling function G(x), which turns out to be in good agreement with numerical experiments. In physical space, quantities related to coherent vortices develop algebraically with time. The dimensional analysis predicts that the total number N of vortices decreases as N∼t−χ with exponent χ=1/2. Moreover, it is found that the remarkable feature of this system is the approximate conservation of the area of the coherent region in the potential vorticity field.
In this article, we introduce a robust non-fragile state feedback controller which is also optimal with respect to a quadratic performance index, using Linear Matrix Inequalities (LMIs). The uncertainties are assumed ...
详细信息
In order to attain multichannel blind deconvolution of linear time-invariant nonminimum-phase dynamic systems. Inouye and Habe (see Proc. IEEE Signal Processing Workshop on Higher-Order Statistics, p.96-100, 1995) pro...
详细信息
In order to attain multichannel blind deconvolution of linear time-invariant nonminimum-phase dynamic systems. Inouye and Habe (see Proc. IEEE Signal Processing Workshop on Higher-Order Statistics, p.96-100, 1995) proposed 1995 a single-stage maximization criterion. The criterion function is the sum of squared fourth-order cumulants of the equalizer outputs, and the coefficients of the equalizer are determined at once. On the other hand, one of possible approaches for multichannel blind deconvolution is to construct an equalizer based on the system identified by higher-order cumulant-matching. In this paper, it is shown that the single-stage maximization criterion is equivalent to a least-squares fourth-order cumulant-matching criterion after multichannel pre-whitening of channel outputs. This result provides us with an important interpretation of the single-stage maximization criterion.
We discuss the pole structure of nD linear systems from a behavioural point of view. We define the notions of irreducible, reducible, manifest and latent poles, which correspond in the classical 1D setting to controll...
详细信息
We discuss the pole structure of nD linear systems from a behavioural point of view. We define the notions of irreducible, reducible, manifest and latent poles, which correspond in the classical 1D setting to controllable poles, input decoupling zeros, observable poles and output decoupling zeros. Our definition of poles can be interpreted in terms of kernel representations, and also allows an integral representation of any zero-input trajectory in terms of system poles.
The article describes how to use the resonance/antiresonance characteristics to design a servo control system. A conventional speed control system with a torsional load is analyzed and redesigned. The system frequency...
详细信息
The article describes how to use the resonance/antiresonance characteristics to design a servo control system. A conventional speed control system with a torsional load is analyzed and redesigned. The system frequency characteristics at the resonant/antiresonant frequencies are derived and used to assign the system dynamic behavior. By analyzing the dominant properties at low and high frequencies, a simple magnitude shaping design is developed, and a relationship between the antiresonance and resonance magnitudes is deduced. It is shown that the developed design provides advantages of good response and easy adjustment. The validity of the proposed method is also examined by experiments on a DC motor drive system.
Direct torque control (DTC) has drawn the attention of the motor drives designers because its implementation requires no position sensor. Crucial to the success of this scheme is the estimation of electromagnetic torq...
详细信息
Direct torque control (DTC) has drawn the attention of the motor drives designers because its implementation requires no position sensor. Crucial to the success of this scheme is the estimation of electromagnetic torque and stator flux linkages using the measured stator voltages and currents. The estimation is dependent only on one machine parameter, stator resistance. The variation of the stator resistance, which is usually in the range of 0.75-1.7 times its nominal value, deteriorates the performance of the drive by introducing errors in the estimated flux linkage's magnitude and its position and hence in the electromagnetic torque. Resistance change also skews the torque linearity thus making the motor drive a less than ideal torque amplifier. Parameter compensation using stator current phasor error has been proposed in literature. To obtain the stator current phasor error, the stator current reference is required which is not usually available in direct torque control schemes. An analytical derivation of the stator current phasor reference is derived systematically from the reference electromagnetic torque and flux linkages. The error between the stator current phasor reference and its measured value is a measure of the stator resistance variation from its set value. For the first time, it is demonstrated in this paper that the DTC motor drive system can become unstable when the set value of the stator resistance in the controller is higher than the stator resistance in the machine. Hence parameter adaptation is not only important for torque linearity but also for stability of the system is shown in this paper.
For very large document collections or high volume streams of documents, finding relevant documents is a major information filtering problem. A major aid to information retrieval systems produces a word frequency meas...
详细信息
For very large document collections or high volume streams of documents, finding relevant documents is a major information filtering problem. A major aid to information retrieval systems produces a word frequency measure estimated from some important parts of the document using neural network approaches. In this paper a fuzzy logic technique and as its simplified case a neural network algorithm will be proposed for this task. The comparison of these two and an alternative neural network algorithm will also be discussed.
For very large document collections or high volume streams of documents, finding relevant documents is a major information filtering problem. A major aid to information retrieval systems produces a word frequency meas...
详细信息
Functional Hazard Assessment (FHA) is being increasingly recommended (e.g. by the Aerospace Recommended Practice-ARP 4754 [SAE94]) as a means of performing hazard identification. However, many of the available example...
Functional Hazard Assessment (FHA) is being increasingly recommended (e.g. by the Aerospace Recommended Practice-ARP 4754 [SAE94]) as a means of performing hazard identification. However, many of the available example applications of this approach (including that given in ARP 4761 [SAE95]) are illustrated either for aircraft-level functions or sub-system functions with obvious and visible functional effects. Our experience is that it can be difficult to apply FHA for lower level aircraft systems (specifically at the level of the engine controller) where, due to the level of complexity and integration with other systems, the overall effects of functional failure are far from obvious. In this paper, we describe the problems we have encountered when applying FHA and the (partial) solutions we have proposed in order to overcome these problems.
暂无评论