An adaptive model predictive control strategy for a class of discrete-time linear systems with parametric uncertainty

In this study, an adaptive model predictive control (MPC) strategy is proposed for a class of discrete-time linear systems with parametric uncertainty. In the presented adaptive MPC, an updating law is firstly designed to update the estimated parameters online. By utilizing the estimated parameters, a standard MPC optimization problem for unconstrained systems is established. Then, to deal with constrained systems, the min–max MPC technique is developed under the set-based approach for the estimated parameters. Furthermore, it is shown theoretically that the recursive feasibility and closed-loop stability can be rigorously proved, respectively. Finally, numerical simulations and comparative analysis are presented to illustrate the superiority of the proposed algorithms in control performance.     

Bargains in the diamond market? How to take advantage from online information

This paper empirically analyses the price of diamonds from different perspectives. The sample data contains detailed information on more than 165,000 diamonds certified by Gemological Institute of America, which can be purchased since July 2016 from a large online diamond supplier. Our empirical analysis allows to extend the classic 4Cs model in several directions as follows: (a) the classical 4Cs model is insufficient in order to explain the price, so that other attributes, such as polishing, symmetry, and fluorescence, must be incorporated to accurately estimate the price of a particular piece; (b) the large sample size allows us to analyse specific price ranges characterized by high market activity; (3) a very detailed analysis has been conducted for round diamonds, incorporating interactions between attributes within the regression model and studying the marginal rates of substitution between diamond weight and alternative characteristics given a certain price. Our model is able to detect diamonds that could constitute a clear market opportunity for buyers. This model can help to select efficient demand options taking advantage of the information available on the website, improving the overall efficiency of exchange in this sector.     

Waste from brewing (trub) as a source of protein for the food industry

The use of agro-industrial waste for food enrichment can be limited, due to taste, odour, colour and other unpleasant characteristics. Trub (brewing waste) has important nutrients, such as proteins and carbohydrates, and phytochemical compounds; however, its applications are hindered by the astringent flavour. In order to reduce the bitterness of trub, aqueous extractions were realized at high temperature (100 °C per 1 h) in five steps. Two fractions were obtained; a liquid fraction (containing bitter compounds) and a solid fraction (the trub after the extraction process; TAP). Both fractions and the trub before the extraction process (TBP) were evaluated. The bitterness of TBP was significantly reduced in TAP while the protein content increased; TAP presented a branched network and changes in its structure. The reduction in bitterness and the high protein content allows the use of trub in the food industry.     

Effect of sintering duration on the sliding-wear resistance of 3Y-TZP dental ceramics

Zirconia doped with 3 mol% yttria (3Y-TZP) is widely employed in prosthetic dentistry. The standard routine in the manufacture of prostheses involves subtractive machining of a commercial presintered block, followed by pressureless sintering up to full densification using one of the heat treatments indicated by the supplier, so as to obtain adequate strength. Usually, however, little information is provided on how these treatments affect the wear resistance. The present work therefore investigated how three sintering cycles of different durations recommended by a commercial supplier affected the microstructure and long-term degradation in the form of sliding-wear of the resulting 3Y-TZP ceramics. It was found that the three cycles essentially resulted in the same wear behavior (ie, wear modes and mechanisms, as well as specific wear rate ~5·10^–6 mm³/Nm). The results are analyzed within the framework of existing abrasive wear models, and implications for the manufacture of durable prostheses are discussed.