Decomposition of ferropericlase (Mg0.80Fe0.20)O at high pressures and temperatures

We have heated ferropericlase (Mg_0.80Fe_0.20)O to temperatures of over 2300 K at pressures of above 100 GPa to investigate the stability of the solid solution at elevated P, T conditions. The in situ X-ray study in laser-heated diamond anvil cells, as well as X-ray powder diffraction and chemical analysis of recovered samples, show that ferropericlase dissociates to magnesium oxide and ferrous oxide rich components. We demonstrate the importance of the combination of different analytical techniques for studies of solid-state chemical processes at extreme conditions.     

Preparation and properties of protein concentrate from broiler chicken heads

The object of this work was to establish the optimal technological conditions for the production of protein concentrate from the heads of broiler chickens by enzymic hydrolysis with papain. It was discovered that hydrolysis is most effective at a temperature of 60°C and a pH of about 7, with 2g of enzyme added per kilogramme of raw material. Under these conditions, 100 kg of heads yielded 7 kg of concentrate and 19.2 kg of waste for feed meal. The concentrate obtained contained about 85% protein and demonstrated good organoleptic and physicochemical properties.     

Sylow's theorem in polynomial time

Given a set Γ of permutations of an n-set, let G be the group of permutations generated by Γ. If p is a prime, a Sylow p-subgroup of G is a subgroup whose order is the largest power of p dividing |G|. For more than 100 years it has been known that a Sylow p-subgroup exists, and that for any two Sylow p-subgroups P₁, P₂ of G there is an element g?G such that P₂ = g^?1P₁g. We present polynomial-time algorithms that find (generators for) a Sylow p-subgroup of G, and that find g?G such that P₂ = g^?1P₁g whenever (generators for) two Sylow p-subgroups P₁, P₂ are given. These algorithms involve the classification of all finite simple groups.     

Model Predictive Control of Structures under Earthquakes using Acceleration Feedback

This paper presents a general formulation of the model predictive control (MPC) scheme with special reference to acceleration feedback in structural control under earthquakes. The MPC scheme is based on a prediction model of the system response to obtain the control action by minimizing an objective function. Optimization objectives include minimization of the difference between the predicted and desired response trajectories, and of the control effort subject to certain constraints. The effectiveness of MPC has been demonstrated to be equivalent to the optimal control. In this study, the prediction model is formulated using a feedback loop containing acceleration measurements from various locations in the structure. The state observer utilizes the Kalman-Bucy filter to estimate the states of the system from the acceleration feedback. Examples of single-story and three-story buildings equipped with control devices are used to demonstrate the effectiveness of the MPC scheme based on acceleration feedback. Both buildings are analyzed using an active tendon control device and an active mass damper (AMD). A two-story building with an AMD is used to experimentally validate the numerical control scheme. The results demonstrate the effectiveness of the MPC scheme using acceleration feedback. The acceleration feedback framework developed in this paper should serve as a building block for future extensions of MPC in capturing and benefiting from the attractive features of MPC, i.e., computational expediency, real-time applications, intrinsic compensation for time delays, and treatment of constraints, for implementation in civil structures.     

Recovery of lanthanides from kola apatite in phosphoric acid manufacture

The paper presents the results of bench-scale studies for the recovery of lanthanides from Kola apatite in the phosphoric acid production by a two-stage hemihydrate-dihydrate wet-process. The second stage of the process (hydration of hemihydrate) provides the best conditions for the recovery of lanthanides. In the postulated recovery process use is made of solvent extraction for the removal of lanthanides during hydration of hemihydrate, and precipitation-stripping for the removal of lanthanides from the solvent. Lanthanides are recovered in the form of Ln-enriched concentrates with an efficiency of 80–85%. The process does not disturb the phosphoric acid production, and additionally purifies the by-product gypsum, so that it can be utilized.