Announcing new books in material science

Announcing new books in material science     

DESIGN AND LEARNING WITH CELLULAR NEURAL NETWORKS

The template coefficients (weights) of a CNN which will give a desired performance, can either be found by design or by learning. ’By design‘ means that the desired function to be performed can be translated into a set of local dynamic rules, while ’by learning‘ is based exclusively on pairs of input and corresponding output signals, the relationship of which may be far too complicated for the explicit formulation of local rules. An overview of design and learning methods applicable to CNNs, which sometimes are not clearly distinguishable, will be given from an engineering point of view.     

Odorants Contributing to Warmed-Over Flavor (WOF) of Refrigerated Cooked Beef

A systematic study was performed to determine the odorants contributing to the warmed-over flavor (WOF) of cooked beef patties. The most potent odorants of the freshly cooked patties and of the cooked, refrigerated and reheated patties showing WOF were screened by dilution experiments. Eleven odorants were selected for quantification by stable isotope dilution assays. Three aroma models were prepared on the basis of the results. A sensory comparison of the models indicated that WOF was the result of a combination of a loss of desirable odorants, e.g. 4-hy-droxy-2,5-dimethyl-3(2H)-furanone and 3-hydroxy-4,5-dimethyl-2(5H)-furanone, along with an increase in lipid peroxidation products, in particular n-hexanal and trans-4,5-epoxy-(E)-2-decenal.     

Alternative Approach in Optimization of Plate Type Heat Exchangers

Plate type heat exchangers are widely used in process industries for gas/gas applications. Typically, these exchangers prove to be very efficient, especially as air preheaters in process furnaces or in equipment used in environmental protection (e.g., in units for thermal disposal of wastes).

For economic reasons, there is a need for a new optimization approach for plate type heat exchanger design and operation. The objective function is to achieve a minimal total annual cost of heat exchangers. Pressure drop and heat transfer are interdependent, and both of them strongly influence capital and operating costs of any heat transfer system. In designing a heat exchanger, it is necessary to determine the optimal dimensions of the apparatus with the given conditions of the equipment operation.

The goal is to obtain the most economically optimal design. An economic assessment allows a comparable estimation of various alternatives. The total annual cost consisting of fixed and variable costs of the heat exchanger was selected as a criterion that summarizes different factors of influence into one objective function. Major cost components of a heat exchange system are as follows: capital, operating and maintenance costs of air and flue gas fans, and capital and maintenance costs of the plate type heat exchanger.

The application of the developed optimization approach is demonstrated through practical industrial examples.     

Acid Durability of Sodium and Potassium Galliosilicate Glasses

The relative chemical durability in nitric acid of three series of glasses in the (Na,K)₂O-Ga₂O₃-SiO₂ system have been studied. In these compositions, gallium is proposed to behave as either a network modifier or former depending on the gallium to alkali ion ratio of the glass. The mechanisms of acid attack as found in the present work are postulated to be a combination of ion exchange and network dissolution dependent upon the glass composition/structure. This results in complex trends in the acid dissolution of these glasses as functions of the gallium to alkali ion ratio, and silica content.     

Structure-Property Relations in Lanthanide Borate Glasses

Glass formation in the system Ln₂O₃-B₂O₃ (Ln = Nd, Sm) was studied. Glasses could be formed in the range from 0 to -28 mol% rare-earth oxide (Ln₂O₃), but liquid immiscibility in these systems limits the range of homogeneous glasses to 0 to 1.5 and 25 to 28 mol% Ln₂O₃. The infrared spectra indicate that the rare-earth-rich glasses are structurally similar to rare-earth metaborates (LnB₃O₆) which contain (B₃O₆)- chains. The variation in density, transformation temperature, thermal expansion coefficient, and transformation-range viscosity of these glasses with the size of the rare-earth ion is discussed. Glasses near the metaborate composition have a transformation temperature of =700°C, which is high for binary borate glasses. Glasses could not be formed in the systems EU₂O₃-, Gd₂O₃-, HO₂O₃-, and Er₂O₃-B₂O₃, even by quenching at =1300°C/s. The sudden lack of glass formation in the system Ln₂O₃-B₂O₃ with Ln³⁺ ions smaller than Sm³⁺ is explained on the basis of the size effect of the Ln³⁺ ion on the stability of (B₃O₆)- chains in these metaborates.