The main purposes of this paper are to illustrate several key issues in the implementation of a conventional Nonlinear Model Predictive Control algorithm on a reasonably large industrial process and to test the effect...
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ISBN:
(纸本)0780345304
The main purposes of this paper are to illustrate several key issues in the implementation of a conventional Nonlinear Model Predictive Control algorithm on a reasonably large industrial process and to test the effectiveness of the Nonlinear Model Predictive Control algorithm recently proposed by Zheng for control of large nonlinear systems with constraints. We show why a conventional Nonlinear Model Predictive Control algorithm may fail to provide integral control under very reasonable conditions (i.e., integral control is guaranteed if and only if a global solution is implemented and the output horizon is infinite) and illustrate this undesirable behavior through simulations on the Tennessee East man process. In addition to computational advantage, we argue that Zheng's algorithm may be preferred based on robust performance consideration.
Existing data models and design principles for temporal databases are based on the assumption that a temporal data is associated with an interval as well as its sub-intervals. This type of temporal data is called homo...
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Existing data models and design principles for temporal databases are based on the assumption that a temporal data is associated with an interval as well as its sub-intervals. This type of temporal data is called homogeneous data. A temporal data which is associated with an interval, but not its sub-intervals, is called a non-homogeneous data. Existing data models cannot capture non-homogeneous data accurately, and the existing design principles are not applicable in temporal databases that contain non-homogeneous data. In this dissertation, the relational data model is extended to support both homogeneous and non-homogeneous data. A design principle which avoids inconsistency in temporal databases, that contain homogeneous data as well as non-homogeneous data, is studied. In the proposed extension of the relational data model, temporal relations are classified into two types; property relations and representative relations. A tuple in a property relation is associated with the valid time and its sub-intervals, while a tuple in a representative relation is associated with only the whole interval of its valid time. Thus, the valid time in a property relation is decomposable, but the valid time in a representative relation is not. Based on this characteristics, the valid time in a property relation and that in a representative relation cannot be used in the same manner. In the extension of relational algebra for temporal relations, the calculation of the valid time in a relation, created by relational operators, is determined by the types of the temporal relations. Thus, it guarantees proper use of the valid time. A type of inconsistency, called P-inconsistency, can occur in temporal databases with homogeneous and non-homogeneous data. A normal form, called P-consistency Normal Form (PCNF), which avoids P-inconsistency, is proposed in this dissertation. PCNF is based on types of attributes, functional dependencies, and property dependencies (P-dependencies), in tempor
The erection of large hydroelectric power stations leads to appreciable changes in hydrothermal and ice river regimes both above and below the hydroscheme. The river regime change affects the adjacent areas ecology. T...
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The erection of large hydroelectric power stations leads to appreciable changes in hydrothermal and ice river regimes both above and below the hydroscheme. The river regime change affects the adjacent areas ecology. To estimate completely the ecologic effect of designed and already constructed hydroelectric power stations, it is necessary to determine the hydrothermal and ice river regime changes. As a methodical basis for the construction of a set of computer algorithms, a method of splitting by physical processes and the module principle has been used. Among the hydro-ice-thermics problems of rivers and water reservoirs are the following: the determination of the temperature regime of a water reservoir, an investigation of stratified flows in a weakly-running water reservoir;an investigation of a hydrothermal river regime;an investigation of ice cover edge dynamics in the downstream of a river. For every problem, mathematical models of different levels of complication and computer programs have been worked out.
Direct Torque control (DTC) is an emerging technique for controlling the PWM inverter-fed induction motor (IM) drives. It allows the precise and quick control of the IM flux and torque without calling for complex cont...
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ISBN:
(纸本)0780339363
Direct Torque control (DTC) is an emerging technique for controlling the PWM inverter-fed induction motor (IM) drives. It allows the precise and quick control of the IM flux and torque without calling for complex control algorithms. In principle, moreover, it requires only the knowledge of the stator resistance. The? tutorial starts by reviewing the basic operation of an IM and of a PWM inverter using the space vector theory. The field-orientated (FO) control of an IM drive is also reviewed. Then the concept of DTC is illustrated and three DTC-based strategies [i.e. Switching Table (ST), Direct Self control (DCS), Space Vector Modulation (SVM)] are described. The ST strategy is dealt with in detail, discussing the results which can be obtained with different choices of the switching table. Problems associated with the selection of the amplitude of the hysteresis bands of the flux and torque controllers are illustrated by means of experimental data. Merits and limits of DTC: are reported and a comparison with FO control is given.
The paper presents a fuzzy logic-based control principle of active and reactive powers in PWM voltage rectifiers. Such a PWM voltage-type rectifier, equiped with the proposed control strategy, may be used advantageous...
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ISBN:
(纸本)0780339363
The paper presents a fuzzy logic-based control principle of active and reactive powers in PWM voltage rectifiers. Such a PWM voltage-type rectifier, equiped with the proposed control strategy, may be used advantageously as an active filter to compensate the unsuitable power factor and/or current high harmonics of nonlinear loads connected to the mains. After the description of this control algorithm, results of simulation are presented and compared with those for the Direct Self Control (DSC) strategy of the PWM rectifiers, which is another new and promissing method, The results of the analysis and simulation performed show that the fuzzy power control method if simple and little sensitive to the changes of input filter parameters, while the number of sensors needed is relatively low. The algorithm works well even for the small values of the input filter inductance and output de capacitance, and exhibits high dynamic capabilities.
We describe a method of object-selective quantizer control in a standard coding system based on MC DCT-CCITT Recommendation H.261. The approach is based on two novel algorithms, namely buffer rate modulation and buffe...
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ISBN:
(纸本)0780331222
We describe a method of object-selective quantizer control in a standard coding system based on MC DCT-CCITT Recommendation H.261. The approach is based on two novel algorithms, namely buffer rate modulation and buffer size modulation. By forcing the rate control algorithm to transfer a relatively small fraction-about 10-15% on average-of the total available bit rate from the coding of the non-facial to that of the facial area, in head-and-shoulders videoteleconferencing sequences, images with better-rendered facial features are obtained, i.e. blocky artifacts in the facial area are less pronounced and eye contact and lip-sync are preserved. The improvement was found to be perceptually significant on video sequences coded at the rate of 64 kbps, with 48 kbps allocated for the input (color) video signal in QCIF format.
Rate-based congestion control is effective and still simple for traffic management in ATM networks. One of its practical realization schemes is the enhanced proportional rate control algorithm (EPRCA) which has been p...
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ISBN:
(纸本)0780325109
Rate-based congestion control is effective and still simple for traffic management in ATM networks. One of its practical realization schemes is the enhanced proportional rate control algorithm (EPRCA) which has been proposed and adopted as a standard for traffic management scheme in the ATM Forum. An analysis for the EPRCA is provided for a network with homogeneous source traffic and a single bottleneck ATM link to investigate the dynamic behavior of the EPRCA. In addition to three types of switches suggested in the EPRCA, a prioritized switch is newly proposed. We exploit the dynamical behavior of the EPRCA and obtain the maximum queue length at the switch and the throughput by using the first-order fluid approximation method. Equations for parameter tuning for the EPRCA are also provided.
Two algorithms for the complete automation of background estimation in ICP emission spectroscopy are presented and evaluated. One of these algorithms is based on heuristic spectral interpretation, while the other is b...
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Two algorithms for the complete automation of background estimation in ICP emission spectroscopy are presented and evaluated. One of these algorithms is based on heuristic spectral interpretation, while the other is based on statistical spectral interpretation. These algorithms both address the weaknesses of the conventionally employed approaches of blank subtraction in calibration and background estimation through interpolation from analyst-selected wavelengths adjacent to the analyte peak. In a rigorous evaluation with synthetic spectra, these algorithms are characterized for performance in terms of accuracy, precision, and robustness. As a demonstration of the algorithms' performance with experimentally measured spectra, a determination of uranium in the presence of a calcium background interference is performed. These algorithms require no analyst interaction for their operation, and they estimate the background for every spectrum measured.
A rounding lemma is presented which has applications in the field of discrete mathematics. The lemma can be used to simplify complex terms and analyse certain recurrence relations.
A rounding lemma is presented which has applications in the field of discrete mathematics. The lemma can be used to simplify complex terms and analyse certain recurrence relations.
Measurement of aortic input impedance in the rat is complicated by a high basal heart rate but is possible if appropriate compensation is made for frequency-dependent errors in modulus and phase resulting from analog ...
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Measurement of aortic input impedance in the rat is complicated by a high basal heart rate but is possible if appropriate compensation is made for frequency-dependent errors in modulus and phase resulting from analog filters in the equipment and from nonalignment of pressure and flow sensors. Because input impedance is a complex quantity, accurate values for both phase and modulus are required before meaningful interpretation of the data can be made. We measured aortic pressure and electromagnetic ascending aortic blood flow in mature, ether-anesthetized, open-chest male Wistar rats. Pressure and flow waveforms were averaged in the time domain and converted to Fourier series. Flow moduli were corrected for the measured frequency response of the flowmeter. Phase spectra were corrected by the classic frequency-domain and two new time-domain methods. Compensation for instrumentation errors was assessed at two different flowmeter filter settings in five animals. Reproducibility, variability, and the effects of vasoconstriction were assessed in 43 animals. Three methods of estimating characteristic impedance from the impedance spectra were evaluated and found to produce comparable results at baseline and following pharmacological elevation of blood pressure with graded methexamine infusion. Physiologically equivalent values for phase, as assessed by comparing oscillatory power calculated from the impedance spectra, were obtained with each of the phase-correction techniques. The new time-domain methods facilitate the assessment of aortic input impedance in this small animal model because they do not require measurement of the spatial separation between pressure and flow transducers and pulse wave velocity in the proximal aorta.
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