The use of neural networks for fitting complex kinetic data

Congrès ESCAPE-3: European Symposium on Computer Aided Process Engineering n.3, Graz , Autriche, 1993In this paper the use of neural networks for fitting complex kinetic data is discussed. To assess the validity of the approach two different neural network architectures are compared with the traditional kinetic identification methods for two cases: the homogeneous esterification reaction between propionic anhydride and 2-butanol. catalysed by sulphuric acid and the heterogeneous liquid-liquid toluene mononitration by mixed acid. A large set of experimental data obtained by adiabatic and heat flux calorimetry and by gas chromatography is used for the training of the neural networks. The results indicate that the neural network approach can be used to deal with the fitting of complex kinetic data to obtain an approximate reaction rate function in a limited amount of time which can be used for design improvement or optimisation when owing to small production levels or time constraints. it is not possible to develop a detailed kinetic analysis.Publicad

Numerical and experimental comparison of on-line methods for detection of thermal runaway events in batch and semi-batch chemical reactors

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.In this paper the results of comparative study carried out for three on-line methods used to detect thermal runaway events in chemical reactors have been presented and discussed. An ability of the criterion of derivatives, the divergence criterion and the algorithm employed neural networks, all used to detect approaching thermal runaways has been compared.dc201

Upgrading from Gaussian Processes to Student's-T Processes

Gaussian process priors are commonly used in aerospace design for performing Bayesian optimization. Nonetheless, Gaussian processes suffer two significant drawbacks: outliers are a priori assumed unlikely, and the posterior variance conditioned on observed data depends only on the locations of those data, not the associated sample values. Student's-T processes are a generalization of Gaussian processes, founded on the Student's-T distribution instead of the Gaussian distribution. Student's-T processes maintain the primary advantages of Gaussian processes (kernel function, analytic update rule) with additional benefits beyond Gaussian processes. The Student's-T distribution has higher Kurtosis than a Gaussian distribution and so outliers are much more likely, and the posterior variance increases or decreases depending on the variance of observed data sample values. Here, we describe Student's-T processes, and discuss their advantages in the context of aerospace optimization. We show how to construct a Student's-T process using a kernel function and how to update the process given new samples. We provide a clear derivation of optimization-relevant quantities such as expected improvement, and contrast with the related computations for Gaussian processes. Finally, we compare the performance of Student's-T processes against Gaussian process on canonical test problems in Bayesian optimization, and apply the Student's-T process to the optimization of an aerostructural design problem.Comment: 2018 AIAA Non-Deterministic Approaches Conferenc

CFD methods for mathematical modeling of pollutants dispersion in atmosphere

Przedstawiono modelowanie matematyczne transportu zanieczyszczeń za pomocą metod CFD. W tym celu zaprezentowany został model dyfuzji burzliwej przy pomocy turbulentnej liczby Schmidta. W pracy przedstawiono wyniki symulacji nieustalonego transportu zanieczyszczeń generowanego przez źródło miejscowe. Modelowanie CFD pozwala na dokładniejsze modelowanie transportu masy niż modelowanie oparte o modele analityczne. Metoda ta wymaga sporego zapotrzebowania na moc obliczeniową.The paper presents the mathematical modeling of pollutants dispersion with the use of CFD methods. A turbulent diffusion model with turbulent Schmidt numbers was formulated. The simulation results dealing with the transient transport of pollutants generated by local source are presented. CFD modeling allows for more accurate modeling of mass transport than modeling based on analytical models. The presented modeling method requires a strong computing power

Integration of chemical processes in a chromatographic reactor

Celem pracy było określenie wpływu integracji dwu procesów (odwracalnej reakcji chemicznej oraz chromatograficznej separacji reagentów) na sprawność zintegrowanego procesu prowadzonego w pojedynczym aparacie. Badany proces zintegrowany nazywany jest procesem chromatografii reaktywnej i prowadzony jest w reaktorze chromatograficznym. Badano wpływ zmiennych operacyjnych na efektywność tego zintegrowanego procesu

Process safety issues in stirred tank reactors

Celem prezentowanej pracy było opracowanie i weryfikacja uniwersalnego kryterium bezpiecznej pracy dla reaktora zbiornikowego o działaniu okresowym i półokresowym. Wykonano serię badań doświadczalnych mających na celu wyznaczenie i weryfikację wykresów granicznych, będących podstawą opracowania tego kryterium. Przeprowadzone badania doświadczalne i testy w pełni potwierdziły przydatność oraz dużą niezawodność opracowanego kryterium bezpieczeństwa.The aim of this study was the elaboration and verification of universal criterion for safe operation of batch and semibatch stirred tank reactors. Series ' of experimental studies were carried out in the RC1 Mettler Toledo reaction calorimeter to determine and verify boundary diagrams on which this criterion is based. The carried out experiments fully confirm applicability and robustness of the elaborated criterion

Nanosilver: A Catalyst in Enzymatic Hydrolysis of Starch

Silver nanoparticles are widely used, because of their antimicrobial properties. In this paper, the rate of starch digestion in the presence of nanocatalyst was compared with the rate of reaction without nanosilver. The rate of enzymatic degradation of starch was found to be increased in the presence of silver nanoparticles. It is considered that α-amylase was immobilized onto the surface of nanoparticles

Aesthetics of mobile media art

The article can be found at URI below.In this article, three London-based creative practitioners examine the new emerging possibilities of mobile media in the domain of art and media practice. The three practice-based research projects reflect their diverse backgrounds and perspectives within the emerging field of mobile media, in an effort to define the new genre of mobile media art aesthetics. Despite the different approaches towards working with mobile media, a shared original aesthetic emerges specific to the mobile phone. The article focuses on the pixilated, low-resolution mobile screen aesthetic, interface, production processes and uses, made possible by the mobile phone, revealing their contribution to the field of screen media in the decade of HD. Within the collaborative examination of the work, the authors attempt to define an emerging category of Mobile Media Art