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91.
Denis Efimov Nikita Barabanov Romeo Ortega 《International Journal of Adaptive Control and Signal Processing》2019,33(12):1885-1900
It is a well‐known fact that linear time‐varying systems with a persistently excited state matrix are exponentially converging and input‐to‐state stable with respect to additive perturbations. Recently, several relaxed conditions of persistent excitation have been presented, which ensure an asymptotic convergence rate in the system. In the present work, it is shown that these conditions are similar and that, under such a relaxed excitation, only nonuniform in time input‐to‐state stability and integral input‐to‐state stability properties can be obtained. The results are illustrated by simulations for a problem of estimation in the linear regression model. 相似文献
92.
Corneliu Hamciuc Elena Hamciuc Marius Olariu Romeo Ciobanu 《Polymer International》2010,59(5):668-675
Aromatic polyimides are high‐performance polymers used in applications demanding service at enhanced temperature while maintaining their structural integrity and excellent combination of chemical, physical and mechanical properties. The incorporation of various metallic additives into a polyimide matrix improves its properties, leading to materials required by specific applications. Hybrid polyimide films containing barium and titanium oxides having thicknesses in the range of tens of micrometres were prepared. These films were obtained using the sol–gel technique starting from a poly(amic acid) and a soluble precursor of metal oxides. They exhibited good thermal stability having an initial decomposition temperature above 460 °C, and a glass transition temperature in the range 217–238 °C. Two subglass transitions, γ and β, were evident from dynamic mechanical analysis and dielectric spectroscopy. A study of the thermal and electrical behaviour of some hybrid polyimide films containing barium and titanium oxides is presented. On increasing the concentration of metal oxides, an increase of dielectric constant and a decrease of thermal stability of the hybrid films were observed. The presence of metal oxides shifted the glass transition temperature and the temperature of the β transition to higher values. Copyright © 2009 Society of Chemical Industry 相似文献
93.
In Chopra et al (2008) [Chopra, N., Spong, M. W., & Lozano, R. (2008). Synchronization of bilateral teleoperators with time-delay. Automatica, 44(8), 2142-2148], an adaptive controller for teleoperators with time-delays, which ensures synchronization of positions and velocities of the master and slave manipulators, and does not rely on the use of the ubiquitous scattering transformation, is proposed. In this paper it is shown that this controller will tend to drive to zero the positions of the joints where gravity forces are non-zero. Hence, the scheme is, in general, applicable only to systems without gravity. We also prove in this paper that this limitation can be obviated, replacing the positions and velocities-that are used in the coordinating torques and the adaptation laws-by their errors. Simulation results illustrate the performance of both schemes. 相似文献
94.
The effects of thermal treatment on green table olives were evaluated as a method to control enzymatic browning, to minimise the microorganism presence and to extend their shelf-life. However this treatment is often responsible for colour alterations, development of off-flavours and unfavourable texture changes. Moreover, the effect of different re-use of the natural brine of fermentation with or without different treatments was investigated. Calcium treatment was suggested to maintain firmness. Firming effects obtained from heat treatment combined with calcium treatment have been attributed to heat-activated pectin methylesterase and/or to increased calcium diffusion into tissues at higher temperatures. The results derived from this study will help in designing new processes which can be applied in table olive industry. 相似文献
95.
Marisa Ziino Concetta Condurso Vincenza Romeo Gianluca Tripodi Antonella Verzera 《Journal of the science of food and agriculture》2009,89(5):774-780
BACKGROUND: Because of the great variability in size, shape, colour, pungency and aroma of Calabrian Capsicum annuum(hot pepper), this study was carried out to furnish producers with information on volatile compounds and capsaicinoid content useful for the genetic improvement of this species. Fully ripened fresh peppers of the most widely cultivated varieties were studied. Capsaicinoid content was determined by reverse phase high‐performance liquid chromatography/diode array detection (RP‐HPLC/DAD). Volatile compounds were determined by headspace solid phase microextraction/gas chromatography/mass spectrometry (HS‐SPME/GC/MS). RESULTS: Sixty‐four volatile compounds were identified, the main classes being alcohols, aldehydes, terpenes and aliphatic branched‐chain hydrocarbons. The ‘Naso di cane’ (C. annuumvar. abbreviatum) variety contained the lowest amount of volatiles, especially alcohols and aldehydes, while the highest levels of capsaicin and dihydrocapsaicin were found in ‘Vulcan’ and ‘Corno di capra’ varieties. CONCLUSION: From statistical evaluation of the data obtained, each variety showed a typical composition of capsaicinoids and volatiles determining the taste and odour of the hot peppers. These results should be useful in the context of research aimed at selecting varieties with the best sensory characteristics. Copyright © 2009 Society of Chemical Industry 相似文献
96.
Luis M. Romeo Irene Bolea Yolanda Lara Jesús M. Escosa 《Applied Thermal Engineering》2009,29(8-9):1744-1751
Compression of CO2 is an essential process in the development of carbon capture and storage (CCS) technologies. In spite of power requirements for CO2 compression could be as much as 100 kWe per tonne CO2, the minimization of energy requirements has received little attention in the literature. Although intercooling compression reduces power requirements, it introduces important cooling necessities that could be minimized.The aim of this paper is the integration of intercooling compression into the low-pressure part of a steam cycle to take advantage of the intercooling heat and analyse the energetic and economical results under different assumptions. Simulation and optimization have been performed in order to evaluate the intercooling configuration, energy requirements and the most cost-effective integration. Results have shown reduction in compression power requirement around 40% and reduction of the incremental COE around 23%. Proposed integration could be used to increase the efficiency of CO2 capture processes and, therefore, to reduce the CO2 capture cost. 相似文献
97.
Jim Romeo 《Plastics Engineering》2021,77(2):12-15
The selection of materials available for 3D printing continues to broaden, as innovative formulations, product applications and end-user needs increasingly influence the extent of process capabilities. 相似文献
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