Optimal control for sustainable consumption of natural resources

In this paper we study optimal policies for a central planner interested in maximizing utility in an economy driven by a renewable resource. It is shown that the optimal consumption path is sustainable only when the intrinsic growth rate of the resource is greater than the social discount rate. The model is formulated as an infinite horizon optimal control problem. We deal with the mathematical details of the problem, develop a precise notion for optimality and establish the existence of optimal control at least when the condition for sustainability is met. We apply the appropriate version of the Pontryagin maximum principle and show a numerical simulation of the optimal feedback law. In the end we present the results along with physical interpretations

IONIZATION INVESTIGATION OF QUICK RIDBERG ATOMS IN THE METHOD OF LASER RESONANCE IONIZATION COLLINEAR SPECTROSCOPY

The ionization investigation of quick Ridberg atoms in longitudinal and cross electric fields due to the radiation of a black body and in a magnetic field is the aim of the paper. As a result the dependence of the collisional background in the method of the collinear laser photoionization of quick atoms at the use on ionizers of various geometry of an electric field has been analysed for the first time. The ionization of quick Ridberg atoms in a constant magnetic field has been described for the first time. Three regimes of this ionization have been indicated. Sections of the collisional excitation of hydrogen quick atoms have been measured for the first time. The ionization of quick Ridberg atoms due to the black body radiation has been observed for the first time. The ionization of quick Ridberg atoms, made by the laser radiation, in a magnetic field has been investigatedAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Structural and Luminescence Properties of (Gd_1−xY_x)₂O₃ Powders Doped with Nd³⁺ Ions for Temperature Measurements

Rare earth activated powders are widely regarded as promising candidates for optical thermometry due to their unique photoluminescence characteristics. The paper presents the structural and luminescent properties of crystalline powders of gadolinium and yttrium oxides (Gd1−xYx)2O3, doped with Nd3+ ions, synthesized by the liquid polymer-salt method. The addition of polyvinylpyrrolidone increases the homogeneity of the mixture and ensures high adhesion of the resulting powders. Scanning electron microscopy shows that powders are μm-sized aggregates, which consist of particles with several tens of nanometers in size. A smooth shift of the diffraction peaks of the powders occurs when Gd is replaced by Y without additional peaks. The successive decrease in the lattice constant of the powders from 10.816 to 10.607 Å confirms the existence of continuous solid solutions in the system. The Stark sublevels of the 4F3/2 → 4I9/2 fluorescent band are shifted to 4 nm when Gd is replaced by Y since the strength of the local field has a stronger effect on the inner F-shell of Nd ions in the case of Y. For thermometry, we chose the ratio of the fluorescence intensities between the Stark sublevels 4F3/2(2) → 4I9/2(2) and 4F3/2(1) → 4I9/2(2). The best obtained sensitivity is 0.22% °C−1 for Nd-doped GdYO3 powder in the range of 10–70 °C. This value of temperature sensitivity, together with radiation and excitation lying in the biological window, opens the possibility of using Nd3+-doped (Gd1−xYx)2O3 powders for real-time thermal probing of under tissue luminescence with sub-degree resolution

In Situ Study of the Painting “Hiroshima I” (1958) by Werner Tübke (1929–2004)

This article presents the results of technical studies of the oil painting by the artist of German origin Werner Tübke “Hiroshima I” (1958). The creative heritage of this author has not been studied enough and represents scattered data on the technology of painting and artistic techniques. The aim of this work was to determine the art materials and painting technology described in his diaries, using the example of his only painting represented in Russia: “Hiroshima I”. For this purpose, an in situ approach was implemented using some simple museum instrumentations—UV-induced visible luminescence, infrared reflectography (IRR), radiography, portable X-ray fluorescence (XRF), Fourier transform Infrared spectroscopy (FT-IR), and polarizing microscopy using microprobes. As a result, the pigment composition of the painting layers could be determined, the painting technology refined, and a previously unknown hidden portrait of Werner Tübke’s father revealed