The results of study of mechanical losses by dynamic methods for silicate, borate, and chalcogenide glasses, metallic glass and glycerol at heating in the glass transition region were analyzed. ...Essential differences between the dynamic viscosity values η* calculated by means of the Maxwell equation based on the relaxation time at the maximum of losses (ωτ = 1) for labile states of glass, and the experimental values of η for the metastable liquid at the same temperature were revealed. The ratio η*/η was systematized in the framework of kinetic theory of glass transition and thermodynamics. An interpretation of the regularities was proposed based on the theory of dynamic properties of liquids. It was shown that different widths of spectra of relaxation times were the most probable reason of the difference between η* and η. The width of spectrum is determined by the degree of ordering of states of compared metastable liquid and glass at the same temperature; it depends on the thermal prehistory of each state. A wider spectrum of relaxation times corresponds to a more ordered state. For the considered glasses, the ratio of the temperature corresponding to viscosity value η* of the metastable liquid to the temperature of α-relaxation maximum (
T
α
) is 1.03 ± 0.01 at
T
α
variation from 190 to 1550 K. It is the evidence that all the relaxation frequencies, constituting both “narrow” and “broad” spectrum are associated with one and the same molecular mechanism. Mechanical losses in the metastable supercooled glycerol are described by the Maxwell equation with high precision for η values from 10
13
to 10
5
Pa s.
In the Russian Federation, the problem of atmospheric air pollution is relevant for most regions. Based on the dispersion calculations, the risk to the Bratsk population’s health from the chemicals ...that pollute the air was assessed. It was found that short-term effects of atmospheric pollution cause non-carcinogenic risks to the respiratory system, the immune and blood systems, systemic disorders and damage developmental processes. More than 95% of the contribution to the aggregate level of acute risks are made by dust, nitrogen dioxide, sulfur dioxide, gaseous fluorides, and benzene. Chronic exposure increases the level of the carcinogenic risk, causes the non-carcinogenic risk to the respiratory system, the skeletal system, blood damage and developmental disorders. More than 95% of the contribution are made by nitrogen oxides, sulfur dioxide, gaseous and poorly soluble fluorides, benzene, benzo (a) pyrene, carbon, hexavalent chromium and dust. A list of 13 priority pollutants that should be regularly monitored in Bratsk was compiled.
The article presents results of the calculation of pollutants emitted into the atmospheric air in Chita. The approach to the zoning of the city territory with a population of more than 350 thousand ...people is described. By the results of calculation and assessment of health risks, which are based on the data of modeling the dispersion of harmful impurities, the zones of exposure to chemical impurities were identified. The zoning by the risk degree is relevant for assessing the danger to the population and the impact on the environment. The list of priority impurities was substantiated, taking into account carcinogenic and/or non-carcinogenic risks, and the results of calculations of dispersion and allocation of marker indicators for emissions from enterprises that make the greatest contributions to the air pollution. The methods used in Chita help identify areas with the greatest risks to public health.
The whole complex of air protection activities has been planned in the RF with its aim to reduce levels of ambient air pollution. It is being implemented actively now and as a result the quality of ...the environment should improve for more than 7 million people. In this study, an algorithm has been suggested for assessing effectiveness of air protection activities. It includes six subsequent stages. The algorithm was tested at heat and power enterprises located in a region participating in the Clean Air Federal project. As a result, it was established that these enterprises were sources of potential public health risks; 70 % of them belonged to high risk categories. Until air protection activities are implemented, heat and power enterprises pollute ambient air in some areas in the city (up to 29.9 single maximum MPC; up to 6.9 average daily MPC; up to 19.0 average annual MPC), create unacceptable health risks (up to 25.8 HI for acute exposure, 22.7 HI for chronic exposure, CRT is up to 3.28∙10-4), and cause more than 87 thousand additional disease cases. Implementation of air protection activities at heat and power enterprises will reduce local levels of ambient air pollution but we still expect hygienic standards to be violated for 10 chemicals up to 3–22 MPC and high health risks are likely to persist (up to 6.5–25.5 HI for acute exposure, 11.9–22.4 HI for chronic exposure, CRT will be up to 3.28∙10-4). Effectiveness of the air protection activities planned at heat and power enterprises corresponds to the target levels of the gross pollutant emissions (reduction by 20.56 % by 2024) set within the Clean Air Federal project but it is estimated as ‘unacceptable’ as per the health harm indicator, which is additional disease cases associated with activities of these enterprises (< 20 %). It is necessary to implement additional air protection activities with respect to 12 pollutants (nitrogen dioxide, particulate matter, carbon (soot), carbon oxide, sulfur dioxide, dihydrosulfide, inorganic dust containing silicon dioxide in %: 70–20, dimethyl benzene, ethyl benzene, benzene, formaldehyde, and kerosene); to use the best available technologies with respect to the most hazardous chemicals; to monitor public health in areas with elevated health risks; to implement complex medical and preventive activities.
Abstract
Very often, when designing and developing radio electronic devices, engineers are regularly faced with the need to solve various kinds of problems to ensure the operation of a product under ...the required mechanical loads or thermal conditions during operation. One of the main issues that arise when conducting thermal modeling of radio electronics is the correct assessment of the results. There are a number of electronic components that need to be cooled, mainly through a printed circuit board: power supply transistors, power diodes, microcircuits, etc. For such elements, 90% (or more) of the heat flux from the component is diverted through the printed circuit board, and then to the radiator. Therefore, when carrying out the simulation, it is necessary to have previously obtained reliable temperature results on the power elements. The use of a detailed 3D model for modeling is most often unjustified and can introduce certain errors in the calculations. This article compares different 3D transistor models and the effect of detailing on the modeling process in CAD SolidWorks.
The article is devoted to the calculation and spatial analysis of the impact levels on the anthropogenic environment as an indicator of atmospheric air pollution in Krasnoyarsk. The population lives ...in conditions of exceeding the standards of environmental pollution for 26 substances (from 516 maximum one-time MAC to 132 MAC daily average). The additive effect of chemicals creates a high level of risk in relation to the population in certain areas of the city. The established levels of aerogenic exposure cause about 80.9 thousand additional cases of diseases of the entire population per year (71.0 cases per 1000 people), which is 4.15% of the actual incidence rate. The priority diseases of the entire population associated with the quality of atmospheric air are diseases of the circulatory system (52.8%), the musculoskeletal system and connective tissue (18.6%), digestive system (14.1%), genitourinary system (7.7%), and the respiratory system (7.7%). The foreground factors determining the formation of the established level of complementary incidence rate associated with atmospheric air quality are 23 chemical substances. The obtained results (zones and factors) can be applied to assess the effectiveness and efficiency of implemented measures to improve the atmospheric air condition.
The results of field experiments, involving HTO scavenging from the atmosphere by precipitation in the vicinity of HT and HTO emission sources, are presented. The experiments were aimed at obtaining ...direct experimental data on atmospheric HTO scavenging for a variety of rain characteristics (rain intensity and drop spectra). The most reliable are the calculations of the rate of wash-out with precipitation with the use of the method of integration of the constant exchange for a spectrum of drops. The results of such calculations are in good agreement with the experimental data and can serve as a basis for the generalized parameterization dependences. It is shown that the exact calculation can be replaced by a simpler formula using the mean-value theorem. For the known approximations of the spectra of the rain drops, formulas were obtained to give parameterization dependence of the rate of wash-out Λ on the intensity of precipitation p. This approach can be used for rapid assessment, as well as to determine parameters of wash-out of gases with precipitation in the numerical complexes, which are used for the calculation of the transfer and removal of impurities from the atmosphere.
The results of the field experiments of HTO washout with rainfall in the vicinity of the HT and HTO emission source are presented. The objective of the current study was to obtain the direct ...experimental data on the impact of raindrops characteristics (rate and spectrum of the drops) on HTO washout from the atmosphere. The results can be applied in for the development and validation of various models of washout.
Parasitism as one of the modes of life is a general biological phenomenon and is characteristic of all viruses, many taxa of bacteria, fungi, protists, metaphytes, and metazoans. Zooparasitology is ...focused on studies of parasitic animals, particularly, on their taxonomy, anatomy, life cycles, host-parasite relations, biocoenotic connections, and evolution. Ecological parasitology is a part of ecology as a discipline studying the relation of living organisms with each other and their surroundings. The present paper contains a critical analysis of the problems, main postulates, and terminology of the modern ecological parasitology.
The most important parameters necessary for creation of population models for three-host species with long-term life cycles are discussed by the example of the ticks Ixodes persulcatus and I. ...ricinus. In these species, specimens of the same biological age may belong to different age cohorts and their calendar age may differ by several months or even years. Accurate estimation of the calendar age of singular individuals is difficult; it is based on the extrapolation by its possible biological age and by belonging to the certain age cohort of a natural population. In order to possess a prognostic value, the population models must predict a single-moment population density of activated hungry specimens of all the three developmental stages and the probability of host-finding in hungry ticks during the questing period. The daily mortality of ticks of different developmental stages and phases of each stage (questing, feeding, preparation for molting, and diapause) should also be known. The population density of questing hungry ticks in the ecosystem is determined by the balance between the recruitment of new individuals into the population, their removal from the population by hosts, the dying of ticks from starvation, and the consumption of ticks by predators. At present, unfortunately, only some of these parameters are sufficiently known.
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