Stochastic approximation and realization of Hankel matrices

Dynamic systems are considered whose outputs can be represented either by a deterministic series of the input variables or by a stochastic series of brownian motion processes. Approximate representations of such series are proposed. The representations are based on the Hankel matrix representation of the series. First, it is shown that any Hankel matrix, belonging to suitable classes, can be approximated in the deterministic and stochastic sense by finite rank Hankel matrices. Then, a method is proposed to design bilinear realizations of finite rank Hankel matrices, effective in the deterministic and stochastic sense.     

Matrix formulae for open and closed-loop approximate model matching in frequency domain

This paper concerns model matching of SISO systems in the frequency domain. The matching uses Pade coefficients and Markov parameters of a reference model of which the final system will be an approximation. Because the matching is approximate, constraints on the structures of both the reference model and the final system can be somewhat relaxed. In this paper an easy-to-implement matrix formulation is derived for both open- and closed-loop matching problems. Some results concerning pole-zero cancellations are presented, along with a number of numerical examples provided to illustrate the usefulness and simplicity of the approach.     

New parameterization of MIMO systems

The parameterization of MIMO systems in the open-loop balanced representation was introduced by Kabamba (1985) to show the advantages of using the balanced canonical form over other classical canonical forms as regards the guaranteed stability and minimality of the representation. The parameterization of MIMO systems in closed-loop balanced representation is introduced: the stability is guaranteed under particular conditions and the minimality is also assured. The importance that such a type of realization plays is fundamental in the synthesis of MIMO systems with assigned characteristic values; this allows us to investigate, for example, the stability of closed-loop systems with a low-order regulator. Indeed, for a defined class of MIMO systems, the introduced parameterization allows us to derive sufficient conditions for the closed-loop dissipativeness and for the stability of the reduced-order compensator, generalizing some results proved for S1SO systems.     

Splitting of some s-domain stability-test algorithms

Some classic s-domain algorithms are first expressed in a unified form. From this, all possible split forms are then derived and classified. In particular, attention is focused on two families of algorithms, which include the standard Routh algorithm and an s-domain Levinson-like algorithm respectively. The related split forms are analysed and compared. Their complexity can be reduced by suitably choosing some scaling factors. It turns out that the usual form of the Routh algorithm, which is intrinsically split, and the simplified version of the split Levinson-like algorithm are substantially equivalent and superior to any other possible split algorithm.     

PURIFICATION OF WET PROCESS PHOSPHORIC ACID BY SOLVENT EXTRACTION WITH ISOAMYL ALCOHOL. PART II. STUDY OF THE IMPURITIES DISTRIBUTION.

ABSTRACT

In the present paper, information about the purifying of wet process phosphoric acid (WPA) by Isoamyl Alcohol (iA) is reported. Distribution coefficients of impurities such’ as Fe, Al, Mg, SO⁼ ₄and F, as well as the distribution of Phosphoric Acid (PA) and Isoamyl alcohol were obtained.

Furthermore the variation of the relative distribution coefficients and selectivities of the different impurities was studied as a function of the PA weight percent (wt%) in the organic phase. Removal of the impurities Fe, Al, Mg and SO⁼ ₄is favoured when decreasing PA wt% in the organic phase. Selectivity of F shows different behaviour, passing through a maximum when plotted against PA wt% in the organic phase     

Recovery of Proteins from Raw Sweet Whey Using a Solid State Sulfitolysis

A simple, efficient method to recover functional proteins from cheese whey was developed. It involves partial sulfitolysis of disulfide bonds in whey proteins using sodium sulfite and solid state copper carbonate catalyst. About 25 to 40% of the initial disulfide bonds were modified within 15 to 30 min at pH 7.0. When treated whey was adjusted to acidic pH, about 70 to 80% of the whey proteins precipitated below pH 5.0. The protein precipitate contained some copper as protein-copper complex. However, extraction of the precipitate with EDTA at pH 4.5 completely removed the copper. The uncomplexed protein showed a U-shaped pH-solubility profile with 100% solubility below pH 3.0 and above 6.0. About 90% of the proteins precipitated in the pH range 4.0 to 5.0. The method could be used on an industrial scale to recover highly functional and nutritional whey protein for use in a variety of products.     

OXYGEN TRANSMISSION RATE of an EDIBLE METHYLCELLULOSE-PALMITIC ACID FILM1

Edible coatings with low potassium sorbate permeability could be used to increase the microbial stability of food surfaces. However, such coatings could induce anaerobic food conditions if their oxygen permeability were low. the oxygen permeability of an edible emulsion film (average thickness, 55 μm), composed of methylcellulose and palmitic acid (weight ratio of 3:1), was evaluated at 24°C, atmospheric pressure, and at different percentages of relative humidity (RH). RH values in the 0–57% range had no significant effect on oxygen transmission rate (OTR); calculated OTR values ranged from 660 to 740 mL O₂ (STP)/m² 24h atm. At 79% RH, the OTR doubled to 1,500 mL O₂ (STP)/m² 24h atm. This effect correlated well with the moisture isotherm for the film which showed a low moisture content in the 0–57% RH range and a rapid increase at higher RH values. OTR values, particularly at high relative humidity, indicate no risk of developing anaerobic conditions on the food surface.     

过滤处理中新型陶瓷滤料的选用

介绍了新型陶瓷滤料的优良特性以及如何正确地选择使用。     

KINETICS OF BIOETHANOL PRODUCTION FROM WHEAT MILLING BY-PRODUCTS

An overview of the potential application of wheat milling by‐products as substrate for bioethanol production is presented. In order to select a suitable microorganism, model fermentations were conducted using glucose and dry baker's yeast. The overall ethanol yield was nearly stable (ca. 0.35 g/g), independent of mash glucose concentration; mashes with 100 g glucose/L resulted in an overall ethanol productivity of 3.48 g/L·h. Slurries containing low‐grade wheat flour (LG) (100, 200 or 300 g/L) were used for simultaneous saccharification and fermentation (SSF) with Zymomonas mobilis. Fermentation performance was evaluated based on ethanol concentration (P), productivity (Q_v), yield (Y_P/S), production rate (Q_p) and glucose consumption rate (Q_s). Mashes containing 200 g LG/L produced about 52 g ethanol/L, with Q_vof 2.17 g/L·h. Based on the relatively high fermentation rate of LG, reaching peak ethanol productivity within ca. 9 h of SSF, considerable savings on fermentation time was achieved. Using Z. mobilis for LG fermentation, P was about 30% higher than that obtained with Saccharomyces cerevisiae.     

磷和超稳Y分子筛在深度脱硫过程中增强效应的研究

采用等体积浸渍法分别制备了由磷单独改性、超稳Y分子筛单独改性、以及磷和超稳Y分子筛共同改性的Ni Mo型催化剂。以胜华催化裂化柴油为原料,对催化剂的催化性能进行评价,并采用Py-IR、HRTEM等方法对催化剂进行了表征。结果表明:由磷和超稳Y分子筛共改性的催化剂总酸量、B酸、L酸最多,所形成活性相较多,催化性能最好。从而证实二者在深度脱硫过程中确实存在催化活性上的增强效应。