Management of patients with acquired valvular heart disease in noncardiac surgery

Valvular heart disease is widespread among general population, mainly in older age groups, who often require noncardiac surgery. As the population ages, the significance of this problem will only increase. The basic principles of perioperative managing such patients by a multidisciplinary team, necessarily including a cardiologist, are systematized and set out in international clinical guidelines, which are regularly updated. Currently, the Russian Society of Cardiology guidelines on management of valvular heart diseases are being prepared for publication. However, specifics of assessment and management of patients when planning noncardiac surgery require more detailed presentation for a cardiology practitioner

Bioaccumulation and Toxicity of Organic Chemicals in Terrestrial Invertebrates

Terrestrial invertebrates are key components in ecosystems, with crucial roles in soil structure, functioning, and ecosystem services. The present chapter covers how terrestrial invertebrates are impacted by organic chemicals, focusing on up-to-date information regarding bioavailability, exposure routes and general concepts on bioaccumulation, toxicity, and existing models. Terrestrial invertebrates are exposed to organic chemicals through different routes, which are dependent on both the organismal traits and nature of exposure, including chemical properties and media characteristics. Bioaccumulation and toxicity data for several groups of organic chemicals are presented and discussed, attempting to cover plant protection products (herbicides, insecticides, fungicides, and molluscicides), veterinary and human pharmaceuticals, polycyclic aromatic compounds, polychlorinated biphenyls, flame retardants, and personal care products. Chemical mixtures are also discussed bearing in mind that chemicals appear simultaneously in the environment. The biomagnification of organic chemicals is considered in light of the consumption of terrestrial invertebrates as novel feed and food sources. This chapter highlights how science has contributed with data from the last 5 years, providing evidence on bioavailability, bioaccumulation, and toxicity derived from exposure to organic chemicals, including insights into the main challenges and shortcomings to extrapolate results to real exposure scenarios

STATISTICAL ANALYSIS OF DYNAMIC CHARACTERISTICS ASYNCHRONOUS ELECTRIC MOTOR WITH CHANGING LOAD PARAMETERS

Abstract: Research of operation electrical machines in transitional mode is an actual task. Modeling dynamic processes with changing load parameters and probabilistic assessment of simulation results allows taking into account the degree of influence of these changes on transient response. An approach to the study of the dynamics of an asynchronous electrical motor under external and parametric perturbations shown. Recommendations was given on the use of this method in solving the problem of identifying the parameters of electric machines

Features of application of sensitivity theory for analysis of influence of parametric disturbances on dynamic properties electromechanical converters

At the design and testing stage of electromechanical converters, the analysis of the influence of parametric perturbations on the dynamic properties of an object using sensitivity theory, which allows to evaluate the quality of operation of electrical machines depending on operating conditions, is relevant. Based on the system of differential equations of a DC motor, the sensitivity equations of the corresponding coordinates were obtained in three parameters. A vector structural scheme of the sensitivity model has been formed, as well as the Simulink-model, with the help of which sensitivity function plots were obtained, which determine the additional motion of the object of study when parameters change within specified limits. It is shown that the largest steady-state values of the sensitivity functions correspond to changes in the moment of inertia. It is revealed that the influence of the moment of inertia on the coordinates of the object of study is the most significant. Where in the coordinate most sensitive to variations in parameters is the rotation speed of the electromechanical converter. The problem of statistical analysis of errors of the output coordinates of a DC motor under the assumption of normal distribution of parametric disturbances was also solved. Simulations were carried out and dispersions and relative estimates of the influence of variable parameters were calculated, and graphs were obtained to estimate the degree of influence of parametric disturbances

Q-tables formation method for automated monitoring of electromechanical converters parameters with application of linear integral criterion

In the process of functioning working sets with electromechanical converters included in their composition, it is necessary to take into account the influence of endogenous and exogenous disturbances that cause deviations of the parameters of electric machines from the nominal values given by the manufacturer in the appropriate documentation. These deviations of the parameters, even those within the permissible range of changes, have a noticeable effect on the quality of functioning of electromechanical converters and working sets as a whole. During the life cycle of the work of electromechanical converters, their parameters change as a result of natural wear and senescence, which necessitates continuous or periodic analysis and monitoring of the state objects under study. The paper considers a method based on the calculation of the linear integral criterion Q and the formation of Q – tables, which allows monitoring the functioning of electromechanical converters with unstable parameters during operation as part of working sets. Simulink – models of linear integral criterion calculation system and system of automated monitoring of electromechanical DC converter parameters are presented, which allow estimating unstable parameters. In these models static characteristics are implemented in tabular form reflecting the dependencies between the parameters of the electromechanical converters and the linear integral criterion. The results of the study allow us to obtain estimates of changes in the unstable parameters of electromechanical DC converters with the required accuracy