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.     

HARDNESS OF COOKED MILLED RICE BY INSTRUMENTAL AND SENSORY METHODS

Fifteen milled rice varieties covering the usual range of amylose content and cooked rice hardness were used in a collaborative study to verify the sensitivity of the present objective method for measuring cooked rice hardness. The grains were cooked either in a rice cooker using a fixed water:rice ratio of 2:1, or by boiling in excess water for the predetermined optimum cooking time for each sample followed by draining. Hardness of cooked rice was measured in an Instron Universal Testing Machine (UTM) using two methods: (1) puncture of 100 individual grains and (2) extrusion through a 30 cm² Ottawa Texture Measuring System (OTMS) cell with either a 3.2- or 4.8-mm-diam. holes plate. Hardness values were compared with sensory scores by a trained panel composed of 11 members. Sensory hardness of the rices cooked in a fixed amount of water showed very good correlation with puncture force (r = 0.94, P < 0.01) and with extrusion force through a 3.2-mm-diam. holes plate (r = 0.94). The correlation coefficient between puncture force and extrusion force was 0.97. Paired comparison test by the sensory panel on three pairs of rices verified consumers' claims with respect to preference between members of each pair and agreed with results of ranking test.     

Sorbic Acid and Potassium Sorbate Permeability of an Edible Methylcellulose-Palmitic Acid Film: Water Activity and pH Effects

The apparent permeability constants for potassium sorbate and sorbic acid through an edible film composed of methylcellulose and palmitic acid (weight ratio 3:1) were evaluated as a function of water activity (a_w) and pH. For films with thickness 55–66 μm, potassium sorbate permeability increased from 2.3 × 10^?10 to 2.0 × 10^?8 (mg/sec cm²)(cm)/(mg/mL) as a_w increased from 0.65 to 0.80. Films were not stable at a_w levels above 0.80. Permeability of the film to sorbic acid at a_w 0.8 decreased from 3.3 × 10^?8 to 9.1 × 10^?10 (mg/sec cm²)(cm)/ (mg/mL) as pH increased from 3 to 7. At pH 3 the undissociated acid was 97.5% and at pH 7 it was 0.4%.     

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.     

AN EXPERT SYSTEM FOR ACADEMIC COUNSELING

In recent years, high enrollment has greatly increased the counseling loads of academic advisors at American colleges and universities. Expert systems can assist academic counselors by solving a relatively easy class of problems which deal with the most encountered cases. In this paper, a prototype expert system, CLASS COUNSELOR, is presented. CLASS COUNSELOR recommends a set of courses after an interactive session with the student. It handles the upper division courses of the undergraduate program in the Department of Electrical Engineering, University of Florida. The program runs on IBM-AT personal computers and compatibles.     

ARTIFICIAL INTELLIGENCE GOES MOBILE

New mobile computing technologies require new paradigms for infrastructure and interaction with mobile and networked devices. For building smart mobile companions for new intelligent services, a number of challenges have to be addressed. We argue that artificial intelligence is a key to a new generation of mobile systems. In this introduction to AI in mobile systems, we present some of the challenges and solutions in this exciting field of research.     

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.     

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.