Optimal input design for model discrimination using Pontryagin’s maximum principle: Application to kinetic model structures

The paper presents a methodology for an optimal input design for model discrimination. To allow analytical solutions, the method, using Pontryagin’s maximum principle, is developed for non-linear single-state systems that are affine in their joint input. The method is demonstrated on a fed-batch reactor case study with first-order and Monod kinetics.     

Modelling the User

The relatively high percentage of people with disabilities in Europe combined with the facts of ageing population, strong relation of impairment to age, and as State of the Art shows, dissatisfaction or even unawareness of people with disabilities of available assistive technology are revealing the necessity to incorporate a user-centric approach that beyond 2nd generation practices will achieve to provide embedded and built-in accessibility solutions, as well as toolkits for developers, for ＂engraving＂ accessibility in existing and emerging mass-market ICT-based products, aiming to make accessibility open, plug and play, personalised and configurable, realistic and applicable in various contexts, keeping always the user in the loop. The AEGIS （Accessibility Everywhere： Groundwork, Infrastructure, Standards） IP （Integrated Project） of the 7th European Framework Programme seeks to determine whether 3rd generation access techniques will provide a more accessible, more exploitable and deeply embeddable approach in mainstream ICT （information and communication technologies）. This paper presents the holistic UCD （user-centered design） implementation plan, upon which AEGIS has been based in order to achieve its targets, starting from modelling its target users, in the most efficient way possible.     

Swelling and photoelastic behaviour of ionized hydrogels of poly(acrylic acid)

Summary The photoelastic and swelling behaviour of poly(acrylic acid) gels swollen in 1 M NaCl aqueous solution was studied as a function of crosslinking degree (1–5 wt.% ethylene glycol dimethacrylate) and degree of ionization _g = 0 – 1. The degree of swelling passes through a minimum at _g – 0.15 regardless of the degree of crosslinking, probably due to the formation of hydrogen bonds between ionized and nonionized carboxyl groups. In the same neutralization region, the equilibrium modulus reaches a maximum; on the other hand, the modulus related to the dry state is independent of for all crosslinker concentrations. Thus the mechanical behaviour of poly(acrylic acid) gels is in accord with the Gaussian theory and no contribution of permanent physical interactions to the modulus is observed. The optical behaviour is more complex — the sign of the stress-optical coefficient C _e changes three times with increasing due to the orientation of the side groups. The analysis of the optical data shows that the C _e value is controlled by the degree of swelling and by the ionization.     

Implementing Daubechies wavelet transform with weighted finite automata

We show that the compactly supported wavelet functions discovered by Daubechies [6] can be computed by weighted finite automata (WFA) introduced by Culik and Karhum?ki [2]. Furthermore, for 1-D case, a fixed WFA with states can implement any linear combination of dilations and translations of a basic wavelet at resolution . The coefficients of the wavelet transform specify the initial weights in the corresponding states of the WFA. An algorithm to simplify this WFA is presented and can be employed to compress data. It works especially well for smooth and fractal-like data. Received: 15 February 1995 / 11 April 1996     

Die polymerisation der lactame XI. Die copolymerisation von 6-caprolactam mit 12-laurolactam

The course of the incorporation of 6-caprolactam and 12-laurolactam into polymer chains during the hydrolytic, cationic and anionic copolymerization for an equimolar ratio of the monomers was studied. During the hydrolytic copolymerization 6-caprolactam is incorporated more rapidly at 260, 230 or 200°C at the beginning of the polymerization process; the differences between incorporation rates of the lactams into the copolymer increase with decreasing temperature. During the cationic copolymerization the incorporation of 12-laurolactam is more rapid by orders of magnitude for the above temperatures at the beginning of the process. Changes in the composition of cationic copolymers as compared to the hydrolytic copolymers are independent of the temperature during the copolymerization. The anionic copolymerization is characterized by a more rapid incorporation of 6-caprolactam into the polymer chain. The differences in the polymerization activity of the two lactams decrease with increasing temperature of the anionic copolymerization. The described course of incorporation of individual monomers, with the various mechanisms of the polymerization, also corresponds to melting points of copolymers in accordance with their composition.     

Critical comparison of methods to determine the energy input for discrete manufacturing processes

High variation can be observed in energy requirement values reported for unit processes as applied in discrete manufacturing. Different methods for determining such values have been suggested, ranging from theoretic energy determination till statistically determined time averaged values based on experimental process measurements. In this paper the theoretic process energy method is compared to results as obtained from two methods suggested for systematic determination of Life Cycle Inventory (LCI) database entries for unit processes. Examples from different process categories are presented to illustrate the discrepancies observed between the approaches and to illustrate the error range linked to the method selection.     

Modifications in the morphology of poly(styrene-co-divinylbenzenes) induced by gamma-ray irradiation

The possibility of increasing the apparent specific surface area of macroreticular styrenic polymers crosslinked to different extent by gamma-ray irradiation was investigated. In order to overcome the protective action of benzene rings and simultaneously minimize the negative effect of chain scission competing with the desired additional crosslinking, it was necessary to optimize both the irradiation dose and the content of divinylbenzene. The best conditions for the radiation-induced post-crosslinking of polymers were assessed on the basis of the resultant apparent BET surface area. Useful morphological changes both in the dry and swollen state were possible to be generated.     

N‐(2‐hydroxypropyl)methacrylamide‐based polymer conjugates with pH‐controlled activation of doxorubicin. I. New synthesis,physicochemical characterization and preliminary biological evaluation

New method of synthesis of water‐soluble polymer‐drug conjugates, exhibiting remarkable anticancer activity in mice models, has been developed. In the conjugates, an anticancer drug doxorubicin (DOX) is attached to a polymer carrier based on N‐(2‐hydroxypropyl)methacrylamide (HPMA) copolymer via a hydrolytically labile hydrazone bond. New methacrylamide‐type comonomers, containing either hydrazide group or hydrazon of DOX, were used for copolymerization with HPMA. In contrast to the synthetic procedure described earlier the new method is simpler, cheaper, and results in a better‐defined conjugate structure. The conjugates are fairly stable in buffer at pH 7.4 (model of blood stream) but release DOX under mild acid conditions modeling the tumor microenvironment. The conjugates showed significant in vivo antitumor activity in treatment of T‐cell lymphoma EL‐4 bearing mice with up to 100% long‐term survivors. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Sequential modeling of a low noise amplifier with neural networks and active learning

The use of global surrogate models has become commonplace as a cost effective alternative for performing complex high fidelity computer simulations. Due to their compact formulation and negligible evaluation time, global surrogate models are very useful tools for exploring the design space, what-if analysis, optimization, prototyping, visualization, and sensitivity analysis. Neural networks have been proven particularly useful in this respect due to their ability to model high dimensional, non-linear responses accurately. In this article, we present the results of an extensive study on the performance of neural networks as compared to other modeling techniques in the context of active learning. We investigate the scalability and accuracy in function of the number design variables and number of datapoints. The case study under consideration is a high dimensional, parametrized low noise amplifier RF circuit block.