Output-feedback control with almost-disturbance-decoupling property—a singular perturbation approach

For square invertible and minimum-phase linear time-invariant systems, a high-gain observer-based control law is proposed. This control law provides internal stability for the closed-loop system and has the almost-disturbance-decoupling properly: that is, the influence of the disturbances on the controlled output can be made arbitrarily small.     

Allowable coefficient perturbations with preserved stability of a Hurwitz polynomial†

Given a polynomial P(s) = a_nsⁿ + a_n?11S^n?1 + … -+ a₁s + a₀ which satisfies the Routh-Hurwitz criterion, a procedure is given for finding non-conservative upper bounds on the allowable variations of the coefficients such that the perturbed polynomial maintains the stability property.     

The biodiversity and evolution of lactic flora during ripening of the Iranian semisoft Lighvan cheese

Ninety‐five isolated strains of Lactic acid bacteria (LAB) were identified from Lighvan cheese. The LAB evolution showed the dominance of lactococci and lactobacilli in the first stage and substitution of these genera by enterococci at the end of ripening. The most predominant strains were Enterococcus faecium (22.44%), Lactococcus lactis ssp. lactis (20.4%), Lactobacillus plantarum (18.36%) and E. faecalis (14.28%), respectively. Eleven and 51 different carbohydrate fermentation profiles were observed according to API 20 STREP and API 50 CH, respectively. API 20 STREP dendogram showed identical fermentation profiles of some E. faecalis and E. faecium strains, indicating that these strains might be well adapted to the whole cheese manufacture.     

MICROBIOLOGICAL, PHYSICO-CHEMICAL AND TOXICOLOGICAL QUALITY OF TRADITIONAL TURKISH CHEESE DESSERTS

ABSTRACT

A total of 100 fresh‐cheese‐based desserts (Hosmerim and Cheese helva) from nine different production areas in Marmara Region of Turkey were studied. There were no statistically significant differences in microbiological composition between Hosmerim and Cheese helva. Mean values of APC, Staphylococcus aureus, molds, yeasts, osmophilic yeasts for Hosmerim were 5.7 × 10⁴, 8.0 × 10², 1.8 × 10³, 2.8 × 10³, 1.6 × 10³ cfu/g, respectively, while coliform bacteria, Escherichia coli and Bacillus cereus were <10 cfu/g. Results for Cheese helva were slightly higher. Salmonella spp. and staphylococcal enterotoxin were not detected in 25 g of any sample. Cheese helva, however, had a significantly lower pH and significantly higher contents of protein, fat and carbohydrates, and thus, also a higher content of dry matter. Within each product category, a large variation was observed for both microbiological counts as well as for the chemical composition. This indicates a lack of standardization in the manufacturing process and prompts for the establishment of appropriate process control measures.

PRACTICAL APPLICATIONS

The aim of this study was to determine the chemical and hygienic quality traits of traditional cheese desserts, namely Cheese helva and Hosmerim. For this purpose, 50 Cheese helva and 50 Hosmerim samples obtained from different regions in Turkey were analyzed on account of their microbiological, physico‐chemical and toxicological properties. The presence of some pathogens in the samples and the variable chemical composition indicate that the production process should be defined in “Codes of Good Manufacturing Practice” and the product characteristics should be codified in order to achieve a product with a defined level of microbiological safety.     

Microwave-assisted pre-ionization experiments on GLAST-Ⅲ

GLAss Spherical Tokamak(GLAST-Ⅲ) is a spherical tokamak with an insulating vacuum vessel that has a unique single-passage capability for incident microwaves.In this work,electron cyclotron resonance heating(ECRH)-assisted plasma pre-ionization in GLAST-Ⅲ is explored for three radio-frequency(RF) polarizations(the O-,X-,and M-modes) at different toroidal-field(TF) strengths and filled gas pressures.The optimum hydrogen pressure is identified for efficient plasma pre-ionization.A comparison of the plasma pre-ionizations initiated by the O-,X-,and M-modes shows prominent differences in the breakdown time,location,and wave absorption.In the case of O-mode polarization,microwave absorption occurs for a relatively shorter duration,resulting in a bell-shaped electron-temperature(T_e) temporal profile.Microwave absorption is dominant in the case of the X-mode,leading to a broader T_e temporal profile.The M-mode discharge contains features of both the X-and O-modes.Efficient plasma pre-ionization is achieved in the X-mode polarization for the intermediate TF strengths(with a central toroidal magnetic field B_0=0.075 T).Traces of the electron-number density show a similar tendency,as revealed by T_e.These results suggest that the X-mode is the best candidate for efficient plasma pre-ionization at low filled gas pressures(~10~(-2) Pa) in small tokamaks.     

Measurements of natural radionuclides in soil samples from Upper Egypt

This paper presents the results of natural radioactivity measured for the soil of Qena using gamma-ray spectrometry at ZSR, Hanover University, Germany. Soil samples of radioactive concentrations of ^238U-series （^234Th, ^214pb, and ^214Bi）, 232Th-series （^228Ac, ^212pb, and ^208Tl） and ^40K were analyzed. Three objectives were set： （1） activity levels by surface soft sampling at 0-30 cm depth, （2） dose rates of gamma radiation, radium equivalent, index hazard, and effective dose, and （3） ambient dose rates.     

Plasma diagnostics by optical emission spectroscopy on manganese ore in conjunction with XRD,XRF and SEM-EDS

Manganese (Mn) is an important industrial mineral. Information about the chemical and phase constitution along with the concentration of impurities presented in Mn ore is compulsory in assessing its suitability for different applications. We performed the qualitative and quantitative analysis of low-grade Mn ore (LGMO) using laser-induced breakdown spectroscopy (LIBS) in conjunction with x-ray diffraction (XRD), x-ray fluorescence (XRF) and scanning electron microscopy (SEM) coupled with energy dispersive x-ray electron spectroscopy (EDS). The optical emission spectra of the LGMO sample displayed the presence of Mn, Si, Ca, Fe, Al, Mg, V, Ti, Sr, Ni, Na, Ba and Li. The plasma parameters, electron temperature and number density were estimated using the Boltzmann plot and Stark broadening line profile methods and were found to be 7500 K±750 K and 8.18±0.8×10¹⁷ cm⁻³, respectively. Quantitative analysis was performed using the calibration-free LIBS (CF-LIBS) method and its outcome along with XRD, XRF and SEM-EDS data showed almost analogous elemental composition, while the LIBS method gave acceptably precise elemental analysis by detecting the low atomic number element Li besides V and Sr. The results obtained using LIBS for the LGMO exhibited its ability as a powerful analytical tool and XRF, XRD and SEM-EDS as complementary methods for the compositional analysis of complex low-grade mineral ore.     

EFFECT OF EMULSIFIERS AND FUNGAL α-AMYLASE ON RHEOLOGICAL CHARACTERISTICS OF WHEAT DOUGH AND QUALITY OF FLAT BREAD

Teftoon, a flat bread made of whole wheat flour, is prepared by hand sheeting of dough, followed by baking. Different emulsifiers, like lecithin, E471 (distilled monoglyceride) and E472 (diacetylated tartaric acid esters of mono- and digelycerid of fatty acids), were added to the flour at various levels ranging between 0.25 and 1.0% w/w, and it was observed that they improved the dough characteristics. Improvement in bread quality parameters, such as force to tear and sensory acceptability, were monitored. Fungal α -amylase was also incorporated into the flour at 5–20 g/100 kg flour basis alone and in combination with the emulsifier. The force required to tear the fresh bread was decreased with emulsifier and enzyme addition; however, E472 addition at 0.75% w/w of whole wheat flour gave the softest bread. The tear force of stored bread significantly increased with storage; however, bread containing E472 showed a less increase in tear force up to a period of 3 days. The sensory acceptability was found to be higher than that of the control bread for emulsifiers, and lower for enzyme at a concentration higher than 10 g/kg flour.

PRACTICAL APPLICATIONS

Flat bread is normally consumed fresh, but the staling phenomenon starts immediately after baking this kind of bread. Today, large-scale production and increased consumer demands for high-quality bread with long shelf life have created the need for functional food additives such as emulsifiers and α -amylase enzyme. Incorporation of emulsifiers and enzyme decreased the hardness of Taftoon bread. Emulsifiers and α -amylase enzyme enhanced the flat bread dough quality. The sensory acceptability also improved with the addition of emulsifiers. Optimizing the amount of emulsifiers and enzyme required for reduction of bread hardness is vital because the quality and price of the final product depend on this parameter.