Constant feedback stabilization of discrete-time systems with random-coefficients†

A method is proposed to effectively stabilize discrete-time systems involving random coefficients. The stability results are both of sample solutions and second moments of system states. The method is handy in that any finite number of steps of a Riccati-like difference equation is sufficient to guarantee the construction of a stabilizing feedback gain. The results are given for cases both with and without the presence of an additive noise term. An easy-to-test stabilizability condition accompanies the method, enhancing its utility.     

USE OF CLARIFYING AGENTS AND ULTRA FILTER TO DECREASE FUMARIC ACID, HMF AND INCREASE CLARITY OF APPLE JUICE

In this study, the effects of eight different processing treatments of apple juice (AJ) production (Process 1: Ultra filtration [UF], Process 2: Activated charcoal [AC], Process 3: polyvinylpolypyrolidone [PVPP], Process 4: Gelatine [G] + Bentonite [B], Process 5: [G + B] + UF, Process 6: [G + B] + AC, Process 7: [G + B] + PVPP and Process 8: [G + B] + Kieselguhr [K]) on the fumaric acid (FA), hydroxymethylfurfural (HMF), color and clearness values of AJ were investigated. With the exception of Processes 1 and 5, AC, K, PVPP, G and B were used at various doses in other processes. FA, HMF, color and clearness values of control sample were determined as 3.24 mg/L, 3.84 mg/L, 48.5 (%T) and 94.1 (%T), respectively. The highest proportional decrement in FA and HMF values of the samples were observed with Process 6 at the level of 5. The fifth level of Process 6 resulted in 35.8% (3.24–2.08 mg/L) and 35.9% (3.84 to 2.46 mg/L) reductions in FA and HMF values, respectively. On the other hand, the best improvement in clearness of AJ was obtained with Process 6 at the fourth level and obtained as 98.9 (%T).     

RESPONSE SURFACE METHODOLOGY STUDY ON THE POSSIBILITY OF NITRITE REDUCTION BY GLUCONO-δ-LACTONE AND ASCORBIC ACID IN TURKISH-TYPE FERMENTED SAUSAGE (SUCUK)

The primary goal of this study was to determine the residual nitrite-reducing effects of glucono-δ-lactone (GDL) and ascorbic acid (AA) in Turkish-type fermented sausage. Response surface methodology was used to investigate the simultaneous effects of processing variables, e.g., nitrite (0–200 mg/kg sausage), GDL (0–0.5% w/w) and AA (0–500 mg/kg sausage) on pH, moisture, residual nitrite, proteolysis, lipolysis, peroxide, yield and sensory score of the sausage. AA significantly ( P <  0.01) decreased the residual nitrite level; however, quadratic effect of AA showed an inverse effect. GDL did not produce the same effect on the residual nitrite level. The processing variables had no prominent effect on the proteolysis, lipolysis and peroxide. GDL and AA addition showed a negative effect on the yield and sensory scores of the sausages. The regression model predicted the optimum residual nitrite content to be 0.75 mg/kg. The critical values for nitrite, GDL and AA to obtain this optimum level were 147.56 mg/kg, 0.17% and 565 mg/kg, respectively.

PRACTICAL APPLICATIONS

Residual nitrite level is a major problem in the Turkish-type fermented sausage product with respect to some health concerns, residual nitrite causes a possible formation of the carcinogenic N -nitrosamines. The results of this study can be applied to reduce the residual nitrite level in sausage and to find the optimum levels of nitrite, glucono-δ-lactone and ascorbic acid levels to maintain the characteristic sausage quality properties. Based on the results, ascorbic acid can be used to reduce the residual nitrite levels in the sausage.     

PEKMEZ-DAIRY DESSERTS FORTIFIED WITH SPRAY-DRIED DAIRY POWDERS: EFFECTS OF THE INTERACTION BETWEEN SKIM MILK POWDER, YOGHURT POWDER AND BUTTERMILK POWDER BY A MIXTURE DESIGN APPROACH

A mixture design approach was used to evaluate the interactions between skim milk powder (SMP), yoghurt powder (YP) and buttermilk powder (BMP) on rheological and sensory properties of dairy dessert mixture samples (DDMS). DDMS was prepared with pekmez powder, which was obtained by spray drying of pekmez, also known as concentrated grape molasses. Among the dairy powders, YP was the component that had the most effect on the viscosity of DDMS. The liking of the panelists was more prominent for the dairy dessert samples including the higher concentrations of YP. Optimum values of SMP, YP and BMP in the mixture were found to be 12–46%, 41–90% and 0–39%, respectively with respect to sensory properties.

PRACTICAL APPLICATIONS

The compositional properties of dairy powders can be changed by their usage at particular combinations, which could give rise to an improvement in their rheological and sensory properties. Such modifications would be of great economical importance to food industry. Dairy powders can be used to improve these properties when optimum combination levels of these dairy powders are taken into consideration. Therefore, information obtained in this study may be useful in practical industrial food product process monitoring and development.     

Implications of a result on observer design for stochastic parameter systems

An earlier result on observer design for stochastic parameter systems is utilized to show that optimal one-step predictors for such systems are mean square stable and to propose a new class of stable estimation schemes.     

FATE OF AFLATOXIN M1 IN KASHAR CHEESE

The distribution and stability of aflatoxin M₁ (AFM₁) in Kashar cheese were investigated. Raw milk samples were spiked with AFM₁ at the levels of 50, 250 and 750 ng/L. Distribution of toxin in milk, cheese curd, whey, kneading brine and cheese, and its stability during ripening were determined by high‐performance liquid chromatography. Concentrations of AFM₁ in curds for each contamination level were 2.93, 3.19 and 3.37 times higher than those in milk. After syneresis, the percentage distribution of AFM₁ was 40–46% in curds and 53–58% in whey indicating that relatively higher concentration of toxin passed to whey. Moreover, by the kneading process approximately 2–5% of AFM₁ passed to kneading brine. Compared to the initial spiking level, the percentage of toxin in cheeses varied between 35–42%. Over a 60‐day storage period, there was no decrease in the concentration of AFM₁, suggesting that the toxin was stable during ripening.     

Dynamic feedback control of stochastic-parameter systems

In this work, the problem of stabilizing a discrete stochastic-parameter system with incomplete state information is addressed. In order to solve this problem, a time-invariant compensator system composed of a constant gain observer and a constant feedback gain, is proposed. The stabilizability conditions depend both on the first and second moments of the stochastic parameters.     

An ant colony optimisation algorithm for balancing two-sided U-type assembly lines with sequence-dependent set-up times

Some practical arrangements in assembly lines necessitate set-up times between consecutive tasks. To create more realistic models of operations, set-up times must be considered. In this study, a sequence-dependent set-up times approach for two-sided u-type assembly line (TUAL) structures is proposed for the first time. Previous studies on TUAL have not included set-up times in their analyses. Furthermore, an algorithm based on the Ant Colony Optimization (ACO) algorithm, which is using a heuristic priority rule based procedure has been proposed in order to solve this new approach. In this paper, we look at the sequence-dependent set-up times between consecutive tasks and consecutive cycles, called the “forward set-up time” and the “backward set-up time”, respectively. Additionally, we examine the “crossover set-up time”, which arises from a new sequence of tasks in a crossover station. In order to model more realistic assembly line configurations, it is necessary to include sequence-dependent set-up times when computing all of the operational times such as task starting times and finishing times as well as the total workstation time. In this study, the proposed approach aims to minimize the number of mated-stations as the primary objective and to minimize the number of total workstations as a secondary objective. In order to evaluate the efficiency of the proposed algorithm, a computational study is performed. As can be seen from the experimental results the proposed approach finds promising results for all literature-test problems.