On parity problems and the functional-link artificial neural network

This paper contains the proof of a theorem on the capability of functional-link artificial neural networks both to represent and to learn the n-dimensional parity problem. The result is obtained by an embedding of the problem into a space of dimension 2ⁿ — 1. It is shown that the Volterra expansion of the data in n-dimensions provides the necessary transformation. By computing the parity function, it is shown that a suitable set of neural network weights can be deduced. Finally, it is demonstrated that 2ⁿ — 1 is the minimum embedding dimension for the problem.The contribution of A Zuderell of the University of Innsbruck is acknowledged.     

Determination of the vapor pressures of select polychlorinated dibenzo-p-dioxins and dibenzofurans at 75-275 °C

Vapor pressures were determined for several polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) at 75-275 °C, extending the available literature data to more relevant temperature regions and providing the first experimental data for 2,3,7-trichlorodibenzo-p-dioxin (2,3,7-TriCD). A modification of the effusion technique, based upon controlling the diffusion of the target compound and subsequent high resolution gas chromatography/low resolution mass spectrometry (HRGC/LRMS) analysis, was proven comparable to other accepted methods for determining the vapor pressures of semi-volatile organic compounds (SVOCs). Vapor pressures for octachlorodibenzo-p-dioxin (OCDD) and octachlorodibenzofuran (OCDF) were in excellent agreement with those reported in literature. The application of the current method for the vapor pressure determinations of eight polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/PCDFs) in the extended temperature range (up to 275 °C) is reported. The extension of the vapor pressures to such temperatures, unprecedented for the PCDDs/Fs, is important for vapor-particle partitioning modeling in regions relevant to PCDD/F formation and control. Estimates for the melting temperatures and enthalpies of sublimation and vaporization are also reported, the latter for which no experimentally determined values have been found in the literature. The use of the method to deliver reproducible, trace concentrations (ppt-ppb) of targets was applied to the calibration of the jet-REMPI/TOFMS as an online detector for low chlorinated PCDDs/Fs.     

Adhesives in construction: A contractor's viewpoint

The development of epoxy- and polyester-based adhesives has dramatically widened the scope of adhesive bonding in the civil engineering industry but the technology of the adhesives used has often been more appropriate to the workshop than to the construction site. There is a need for the suppliers of structural adhesives to recognize this and to develop compositions and application techniques more amenable to site use. It is equally necessary for the construction industry to make more effort to understand these materials, to take advantage of their outstanding properties, and hence to use them successfully for the construction and repair of concrete structures.     

Clonal variation in reproductive response to temperature by a potential bulking control agent, Lecane inermis (Rotifera)

The novel idea of using rotifers Lecane inermis (Rotifera, Monogononta) as a tool to overcome activated sludge bulking generates an on-going need to study rotifer biology. The results of biological research on rotifers can serve to improve the method so that it can be most effective when applied in treatment plants. The aim of this study was to test the effect of temperature on four selected rotifer clones originating from different treatment plants. The rate of population development from a single individual (parthenogenetic female) during a 10-day experiment was measured at three temperatures: 8, 15 and 20 degrees C. The temperatures used reflect the annual temperature distribution in the majority of municipal wastewater treatment plants in the temperate zone. The growth rate coefficient (r) and doubling time (tD) were calculated for each clone. Under the most favourable conditions (20 degrees C), rvalues varied between 0.41 and 0.47 d and doubling time between 1.5 and 1.7 d. At a temperature of 15 degrees C, the doubling time was approximately two times longer (2.5-3.4 d). The strongest intraspecific variations were observed at the lowest temperature of 8 degrees C. At this temperature, one of the clones almost failed to proliferate, and another exhibited a doubling time of 7.9 d. The doubling times were a few times greater for the remaining two clones (60 d for Lk1, 33.3 d for Lk4). These results could be very useful in predicting the chances that the rotifers would survive in a biological reactor in a wastewater treatment plant at the temperatures used in these reactors.     

Highly Enantioselective Production of (R)-Halohydrins with Whole Cells of Rhodotorula rubra KCh 82 Culture

Biotransformation of ten α-haloacetophenones in the growing culture of the strain Rhodotorula rubra KCh 82 has been carried out. Nine of the substrates underwent an effective enantioselective reduction to the respective (R)-alcohols according to Prelog’s rule, with the exception of 2-chloro-1,2-diphenylethan-1-one that was not transformed by this strain. The expected reduction proceeded without dehalogenation, leading to the respective (R)-halohydrins in high yields. The use of this biocatalyst yielded (R)-2-bromo-1-phenyl-ethan-1-ol (enantiomeric excess (ee) = 97%) and its derivatives: 4''-Bromo- (ee = 99%); 4''-Chloro- (ee > 99%); 4''-Methoxy- (ee = 96%); 3''-Methoxy- (ee = 93%); 2''-Methoxy- (ee = 98%). There were also obtained and characterized 2,4''-dichloro-, 2,2'',4''-trichloro- and 2-chloro-4''-fluoro-phenyetan-1-ol with >99% of enantiomeric excesses.     

Solution of the inverse problem in solidification of binary alloy by applying the ACO algorithm

The paper presents a solution of the inverse problem consisting in reconstruction of the heat flux and the distribution of temperature in the process of binary alloy solidification when the temperature measurements in the selected points of the alloy are known. The considered task is mathematically modelled by means of the heat conduction equation with the substitute thermal capacity and with the liquidus and solidus temperatures varying in dependence on the concentration of the alloy component, whereas for describing the concentration the lever arm model is applied. An important part of the procedure consists in minimization of some functional executed with the aid of ACO algorithm.