617 research outputs found

    Activity of the right cardiac ventricle and metabolism in healthy persons during an orthostatic test after short term immobilization

    Get PDF
    A 15 minute orthostatic test was performed on healthy male volunteers under conditions of catheterization of the right ventricle of the heart and the radial (or brachial) artery before and after 5 day bedrest in an antiorthostatic position of the body (with the foot of the bed raised 4.5 degrees). The change to a vertical position after immobilization was attended by a more marked increase in the rate of cardiac contractions, an increase of max dp/dt pressure in the right ventricle, and a decrease of cardiac and stroke indices. The decrease of the cardiac index was compensated for, to a certain measure, by a further increase in the extraction and utilization of O2 by the tissues. The arterial blood pH did not change essentially, while the decrease in pCO2 and content of standard bicarbonate was more marked

    The stabilization of unstable detonation waves for the mixture of nitromethane/methanol

    Get PDF
    Mass velocity profiles of detonation waves in mixtures of nitromethane with acetone and methanol with added diethylenetriamine sensitizer were measured using a VISAR laser interferometer. It was found that even small, about 1%, concentrations of acetone and methanol, inert diluents, led to instability of the one-dimensional detonation front in nitromethane. The results of the experiment show that the use of the sensitizer is an effective method of flow stabilization and if the concentration of the inert diluent does not exceed 10%, the detonation front becomes stable with the addition of 1% diethylenetriamine. At a higher diluent concentration, the sensitizer does not suppress the instability but decreases the oscillation amplitude by several times. The addition of diethylenetriamine to the mixture has been found to increase the detonation velocity

    Optimizing integrated steelworks process off-gas distribution through Economic Hybrid Model Predictive Control and Echo State Networks

    Get PDF
    Steel production in integrated steelworks involves the simultaneous production of various byproducts, including process off-gases that are usually exploited for generating electricity in the internal power plant, heat and steam. Their discontinuous production is managed through complex network, gasholders and torches, which must be managed with stringent operational constraints. In this paper we present a supervision and control system designed to optimize the economic management of the distribution of process off-gases that also allows minimizing the environmental impact. The system implements a digital twin based mainly on machine learning techniques, including Echo State Networks, and a hierarchical optimization system, which first level is based on an economic model predictive approach and the second level is based on the economic hybrid model predictive control. This system allows to effectively maximize the use of off-gases while minimizing the environmental impact of their use up to 97%

    Piecewise smooth systems near a co-dimension 2 discontinuity manifold: can one say what should happen?

    Full text link
    We consider a piecewise smooth system in the neighborhood of a co-dimension 2 discontinuity manifold Σ\Sigma. Within the class of Filippov solutions, if Σ\Sigma is attractive, one should expect solution trajectories to slide on Σ\Sigma. It is well known, however, that the classical Filippov convexification methodology is ambiguous on Σ\Sigma. The situation is further complicated by the possibility that, regardless of how sliding on Σ\Sigma is taking place, during sliding motion a trajectory encounters so-called generic first order exit points, where Σ\Sigma ceases to be attractive. In this work, we attempt to understand what behavior one should expect of a solution trajectory near Σ\Sigma when Σ\Sigma is attractive, what to expect when Σ\Sigma ceases to be attractive (at least, at generic exit points), and finally we also contrast and compare the behavior of some regularizations proposed in the literature. Through analysis and experiments we will confirm some known facts, and provide some important insight: (i) when Σ\Sigma is attractive, a solution trajectory indeed does remain near Σ\Sigma, viz. sliding on Σ\Sigma is an appropriate idealization (of course, in general, one cannot predict which sliding vector field should be selected); (ii) when Σ\Sigma loses attractivity (at first order exit conditions), a typical solution trajectory leaves a neighborhood of Σ\Sigma; (iii) there is no obvious way to regularize the system so that the regularized trajectory will remain near Σ\Sigma as long as Σ\Sigma is attractive, and so that it will be leaving (a neighborhood of) Σ\Sigma when Σ\Sigma looses attractivity. We reach the above conclusions by considering exclusively the given piecewise smooth system, without superimposing any assumption on what kind of dynamics near Σ\Sigma (or sliding motion on Σ\Sigma) should have been taking place.Comment: 19 figure

    Influence of Carboxylic Acids on Filterability and Quality Level of Synthetic Low Alkaline Calcium Sulfonate (Detergent-Dispersant Motor Oil Additive)

    Get PDF
    The study examined the conditions of synthetic low alkaline calcium sulfonate (SLCS) synthesis, which is added to motor oils as a detergent-dispersant additive. In particular, the effect of the introduction of carboxylic acids at the stage of SLCS synthesis on such characteristics of the additive as the observable filterability, volume filtration rate, volume fraction of sediment and kinematic viscosity was studied. For the obtained additive samples the average sizes of particles dispersed in the volume were measured using the dynamic light scattering method (DLS) and the basic physicochemical parameters were determined

    Sliding mode control of quantum systems

    Full text link
    This paper proposes a new robust control method for quantum systems with uncertainties involving sliding mode control (SMC). Sliding mode control is a widely used approach in classical control theory and industrial applications. We show that SMC is also a useful method for robust control of quantum systems. In this paper, we define two specific classes of sliding modes (i.e., eigenstates and state subspaces) and propose two novel methods combining unitary control and periodic projective measurements for the design of quantum sliding mode control systems. Two examples including a two-level system and a three-level system are presented to demonstrate the proposed SMC method. One of main features of the proposed method is that the designed control laws can guarantee desired control performance in the presence of uncertainties in the system Hamiltonian. This sliding mode control approach provides a useful control theoretic tool for robust quantum information processing with uncertainties.Comment: 18 pages, 4 figure

    The Environmental Agenda in the Election Programs of Russian Political Parties

    Get PDF
    The article is devoted to the study of environmental agenda in the Russian political field on the example of the analysis of the election programs of Russian political parties. The study analyzes the factors and features of the inclusion of the environmental issues in the political programs of Russian political parties. The main environmental problems raised by political parties and the dynamics of its considering were highlighted, and the specific of their discursive representation were analyzed. The study revealed the following features of the appeal of political actors to environmental issues: techno-utopianism as an unconditional belief in “green technologies” that does not imply major institutional changes; eco-populism, manifested in the connection of environmental problems with more popular social issues; ritualization as a formal mention of the “green” agenda, which does not receive careful consideration. Special attention was paid to the (un)formation of the climate agenda in Russia, which showed the limitations of the global process influence on the Russian political agenda. The study was carried out on the basis of a qualitative methodology

    Multiple hafnium germanate interphase for SiC / SiCf composites

    Get PDF

    XPS Investigation of ceramic matrixes for disposal of long-living radioactive waste products

    Get PDF
    The synthesis of ceramic matrixes for the long-term storage of highly active radionuclide wastes and determination of physical and chemical forms of radionuclides in them is one of the important problems in radioecology. It enables to create purpose fully materials for the long-term storage of radionuclides. In the present work the samples of ceramics [CaCe0.9Ti2O6.8(I) and CaCeTi2O7(II}] formed under various conditions were investigated with the X-ray photo electron spectroscopy. It is necessary for synthesis of ceramic matrixes, for the disposal of the plutonium and others tetravalent actinides. A technique was developed for the determination of cerium oxidation state (Ce3+ and Ce4+) on the basis of the X-ray photo electron spectroscopy spectral structure characteristics. It was established that the sample (I) formed at 300 MPa and T = 1400 °C in the air atmosphere contained on the surface two types of cerium ions in the ratio – 63 atomic % of Ce3+ and 37 atomic % of Ce4+, and the sample (II) formed at 300 MPa and T= 1300 °C in the oxygen atmosphere contained on its surface two types of cerium ions also, but in the ratio – 36 atomic % of Ce3+ and 64 atomic % of Ce4+. It was established that on the surface of the studied ceramics carbonates of calcium and/or cerium could be formed under influence of the environment that leads to the destruction of ceramics
    corecore