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Control of a linear plant, with bounded control input, may be implemented by constructing a control law generator which produces the optimal control as a function of the state variables. If the plant parameters differ from their nominal values, then maintaining optimal control by changing the control law generator is inconvenient since the control law is usually nonlinear. It is shown that in certain cases optimal control can be maintained without changing the control law generator. This is accomplished by using a linear transformation of state variables as the input to the control law generator. The variations of the plant are compensated for by changing the linear transformation. The conditions under which this is possible are established in this paper. The advantage of this system is that a change in a linear function is easier to implement than a change in a nonlinear function. It is shown how this system can be incorporated into an adaptive system which compensates for plant variations. 相似文献
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Mircea Chipara Dorina Chipara Karen Martirosyan Ananta Adhikari Alexandro Trevino 《应用聚合物科学杂志》2024,141(4):e54850
Non-isothermal thermogravimetric analysis in air, of polyoctenamer-single wall carbon nanotubes (PO-SWNTs), loaded by various amounts of SWNTs up to 10% wt., at different heating rates (ranging from 5 to 40°C/min) is reported. The thermal degradation in the air of PO_SWNTs is dominated by a main single sigmoidal dependence, assigned to the polymer and eventually polymer-nanofiller interphase, over which a weaker sigmoid assigned to the thermo-oxidative degradation of the nanofiller is superimposed at higher temperatures. The temperature at which the nanocomposite's residual mass fraction reaches x% wt. of the initial mass, Tx%, is reported (for x = 5, 50, and 85). The dependence of Tx% on the heating rate and the loading by nanotubes is analyzed. The temperature derivative of the thermograms defines new parameters (inflection residual mass fraction and inflection temperature) and (degradation) width. Their dependence on the loading by SWNTs was reported. Estimation of the interphase in polymer-based nanocomposites is based on the postulate that the dependence of the inflection temperature on the composition of the nanocomposite obeys a Fox-like dependence, where the bulk polymer and the polymer trapped within the interphase are considered as a blend of two miscible polymers. Complementary Raman, x-ray diffraction, and differential scanning calorimetry support these results. 相似文献
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Alexandro Baldassin Felipe Goldstein Rodolfo Azevedo 《Journal of Parallel and Distributed Computing》2012
Single-core architectures have hit the end of the road and industry and academia are currently exploiting new multicore design alternatives. In special, heterogeneous multicore architectures have attracted a lot of attention but developing applications for such architectures is not an easy task due to the lack of appropriate tools and programming models. We present the design of a runtime system for the Cell/BE architecture that works with memory transactions. Transactional programs are automatically instrumented by the compiler, shortening development time and avoiding synchronization mistakes usually present in lock-based approaches (such as deadlock). Experimental results conducted with a prototype implementation and the STAMP benchmark show good scalability for applications with moderate to low contention levels, and whose transactions are not too small. For those cases in which a small performance loss is admissible, we believe that the ease of programming provided by transactions greatly pays off. 相似文献
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Edu Grieco Mazzini Júnior Juliana Donato de Almeida Cantalice Alexandro Mangueira Lima de Assis Johnnatan Duarte de Freitas Ligia Maria Manzine Costa Adriana Santos Ribeiro 《应用聚合物科学杂志》2020,137(46):49804
This work provides a convenient low-cost strategy for fast fabrication of dansyl-based fluorescent nanofibers for development of latent fingerprints aiming forensic applications. Polycaprolactone (PCL) and dansyl cadaverine (DnsCad) or dansylglycine (DnsGly) nanofibers are prepared by electrospinning technique and characterized by SEM, FTIR, thermal analysis, and fluorescence spectroscopy. The electrospun PCL/DnsCad and PCL/DnsGly nanofibers are fluorescent with greenish blue and yellowish green emission, respectively. Such nanofibers are useful for enhancement of the visual contrast of latent fingerprints on metallic surfaces when exposed to UV light. These findings are particularly important for development of latent fingerprints on cartridge cases. 相似文献
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While the Padé approximation can often be used to produce good reduced-order transfer functions, the method suffers from the disadvantage that a stable reduced order-model is not always obtained for an original model that is stable. A method is described for obtaining stable partial Padé approximation reduced-order models. The method permits the determination of the effect of changes in the coefficients in the partial Padé approximation on the poles of the reduced-order transfer function by means of standard root locus plots. 相似文献
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A new frequency-domain stability criterion employing a Popov-type multiplier is obtained for a class of nonlinear sampled-data control systems containing a monotonically nondecreasing nonlinearity. This criterion is an extension of previous results, in that unlike other criteria of this type, no upper bound is placed on the derivative of the nonlinearity. An example is given in which this new criterion is used to obtain stability conditions for a non-linear sampled-data system. These conditions are less restrictive than those obtained using other stability criteria. 相似文献
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A new class of pulse-frequency modulated (PFM) control systems, called discrete sigma PFM (DΣPFM), is presented. This new class has properties very similar to sigma PFM (ΣPFM) systems. In addition, sufficient conditions for the asymptotic stabililty of this new class are given utilizing an extension of the Popov stabiity criterion. 相似文献
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Alexandro Garro Brito 《IEEE/CAA Journal of Automatica Sinica》2019,6(1):142-147
In the Ziegler-Nichols's method of reaction curve, the proportional gain should be calculated as an inverse relation of the plant steady-state gain. One of the reasons behind this is to avoid an excessively high loop gain, which can jeopardize many required characteristics of the closed loop. However, many reports, scientific papers and books have been neglecting such gain compensation in the tuning formulae.This brief presents a comprehensive discussion about such uncompensated tuning rules. The main paper finding is that either the stability margin or the disturbance rejection is reduced in this case. A theoretical analysis is performed to obtain the main result. Moreover, a consistent simulation study is also performed to show the impact of the lack of compensation on performance. 相似文献
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Edgar Iván Jimenez-Ruiz Alfonso Nivardo Maeda-Martínez Víctor Manuel Ocaño-Higuera Maria Teresa Sumaya-Martinez Leticia Monica Sanchez-Herrera Oscar Alexandro Fregoso-Aguirre Jesús Ernesto Rincones-López Yolotzin Apatzingan Palomino-Hermosillo 《Journal of Food Processing and Preservation》2020,44(7):e14529