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Number of results: 84
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Abstract

The paper contains the economic analysis of the carried out modernisation of the facilities of a water-park consisting in fitting solar collectors for heating of tap hot water and central heating system. The article presents the data showing investment outlays, operating costs and the calculations concerning the payback time.
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Abstract

The paper contains the technical analysis of the carried out modernisation of the facilities of a water-park consisting in fitting solar collectors for the heating of tap hot water and central heating system. The article includes information on the modernisation carried out with a particular emphasis on analysing the way in which the equipment has been selected and technical solutions employed.
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Abstract

The paper presents selected issues relating to the energy analysis of the air heat pump for hot water. Experimental studies on a test stand made it possible to verify the operational parameters of the heat pump under actual conditions of use. The study shows that heating the water in the storage tank with the capacity of 130 dm3 from 25°C to 40°C took approximately 60 minutes and the water heating for another 5°C took 30 minutes longer. The heat pump process in the field of higher water temperature in the tank is less effective, thus heating the water in the tank above 50°C is less favorable economically.
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Abstract

This paper presents the results of measurements of the operation of a photovoltaic system, connected to the power grid. The intensity of solar radiation and the ambient temperature in the location of the installation were simultaneously recorded in different weather conditions on selected days throughout the year. For the combined results the analysis of correlation in terms of efficiency of individual exemplary photovoltaic installation was conducted.
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Abstract

The analytical method of calculation of a withstand motion of fine-grained mixture is worked out in the vertical cylindrical sieve of vibrocentrifuge. Integration of differential equalization of motion is show out the reserved formulas for the calculation of kinematics descriptions of grain flow. The two-parameter continual model of the state of separation mixture is used in researches, as a heterogeneous continuous environment with variable specific mass (by porosity) on the thickness of movable layer of friable material. Change of specific mass on a radial coordinate in the cylindrical layer of mixture approximated by the function of degree, the coefficients of that are certain by the Aitken's method. Due to such approximation, the analytical decision of differential equalization of the grain flow, shown out with the use of two-parameter rheological dependence, in that the constituent of linear viscid resistance is complemented by the constituent of remaining internal dry friction, proportional overpressure in mixture, is built. An analytical decision is expressed as squaring that is not expressed through elementary functions in closed form, the close method of calculation of integral offers that is why, with the use of partial sum of row of degree. The results got close formulas result in that well comport with the results of numerical computer integration of squaring. Such method the continual models of grain flow on vibrosieves, it is assumed in that friable material is fully confined internal dry friction, are generalized known for, as a result of vibrodilution. The examples of calculations are considered, where influence of different factors is investigational, in particular values of rheological coefficients and change of porosity, on kinematics descriptions. It is set that calculation kinematics descriptions of grain flow substantially depend not only on the thickness of movable layer and rheological constants, and also from the concentration of grains near free surface of the mixture. Thus, worked out here a method of research of vertical grain flow in the cylindrical sieve of vibrocentrifuge can be an alternative to other methods in that for the calculation of motion of grain mixture of variable porosity conducted numerical computer integration of nonlinear differential equalizations.
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Abstract

The formulas have been entered and approved for the calculation of porosity distribution on the thickness of layer of fine-grained mixture during its separation by the inclined flat or vertical cylinder vibro sieves. It has been attained as a result of approximation of tabular information of the obtained numerical computer integration of the specially worked out nonlinear differential equations of the second order in a dimensionless form. For approximation, the function of degree coefficients and index is used for the degrees which are certain by the Aitken's method. Coefficients of the entered analytical dependence are the vibro sieves related to the parameters obtained by mechanical descriptions of the separated material. Coefficients of the entered analytical dependence are related to the parameters of vibro sieves and mechanical descriptions of the separated material. In the case of cylinder vertical vibro sieve the action of centrifugal force is also taken into account. The method of mixture porosity calculation does not need a computer numerical integration of nonlinear differential equations conducted by other authors for solving this problem. Comparison of numerical results of the proposed analytical method of calculation with the ones described in literature, have confirmed its high accuracy results, for the differences do not exceed one percent. The expounded method is universal enough and simple in use, besides it opens the possibilities of subsequent analytical integration of differential equalizations of motion at the calculation of kinematics descriptions of grain flow. The developed method gives the opportunity to also solve the inverse task when, according to experimental measurements of porosity values of grain mixtures on the thickness of movable separated layer, it is needed to find the value of phenomenological permanent that is included in the expressions of coefficients of initial differential equalization. In this way, the adequacy of the mathematical model is improved. The use of approximation of degree considerably simplifies the method of authentication of differential equalization coefficients. In the article, the examples of grain mixture porosity calculation as well as the examples of phenomenological permanent authentication have been resulted after experimental calculations for both the variants of vibro sieves.
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Abstract

The aim of the studies was to evaluate the influence of sowing rate, foliar fertilization (Basfoliar fertilizer 6-12-6) and chemical composition on the mechanical properties of narrow- leaved lupine seeds of cultivars Bojar and Regent. Single seeds were burdened in the direction perpendicular to the parting plane of cotyledons with constant speed 10 mm∙min-1. The crop year and cultivar have significantly differentiated the value of all the analyzed strength parameters of narrow-leaved lupine seeds. The seeds of cultivar Bojar had significantly higher values of all the strength parameters. The designated strength parameters of lupine seeds were negatively correlated with ash content, fiber and protein except for the destructive force. They were also positively correlated with the fat content.
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Abstract

The support for the stable functioning of business entities with focus on their further development is impossible without an effective system of financial security, because any time there is a danger of implementing a variety of risks that can lead to the onset of the crisis. It should be noted that the implementation of measures to ensure financial security is most effective when they are applied long before the crisis - it makes business entities able to recognize early trends of crises and have time for preparedness. In the case when it comes to the global economic crisis, which cannot be prevented, timely measures to ensure financial security can minimize its negative effects, and if the crisis is expected at the level of the enterprise, it will be able to avoid it altogether. The study clarified the theoretical basis of ensuring the business entity financial security - namely, the definition of "financial security" and a list of its tasks, functions and principles. The existing problem of providing financial security are researched. A qualitative and quantitative methods for assessing the financial condition of a business entity are showed. The research has established that the main problems of ensuring the financial security of business entity need to be addressed at the state level, but the early assessment of external and internal environment of economic units significantly reduces the risk of certain threats and thus increases financial security of business entities. The showed methods of assessing the financial situation can be used in practice of national business entities.
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Abstract

Based on the example of the pilot area in Kiev the influence of the increased static load on the superstructure of the stress-strain state of the slope was studied. The efficiency of the proposed methodology when considering the work of "home-slope-retaining structure" depending on natural and anthropogenic factors was demonstrated.
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Abstract

Monitoring of the mechanical properties of fruit obtained from cucumber plants is extremely important because of their use in processing, since these properties are reflected by the finished products of processing. Mechanical defects produced at the time of harvesting, during transport and at the specific stages of processing may adversely affect the course of technological processing (brine and vinegar pickling), resulting in spoilt preserves no longer useful for commercial purposes. The study was designed to identify selected mechanical properties in fresh and pickled fruit obtained from field cucumbers during spontaneous fermentation and fermentation promoted by selected lactic bacteria cultures. Additionally, water contents were measured in fresh cucumbers. The findings show significant differences between the analysed parameters.
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Abstract

The study has identified selected mechanical properties of fresh and stored fruit of large cranberry. The analyses focused on the changes in the values of peel and flesh puncture strength in the selected cranberry varieties depending on water content and storage duration. Measurements were also performed to examine deformations and energy needed to cut through the fruit peel and flesh. The value of breaking stress was calculated. The findings show a decrease in the relevant parameters during storage of fruit obtained from the examined varieties of large cranberry. Mean water contents in the fruit of the relevant varieties were in the range of 86.4-89.1%. There was a notable decrease in the mean value of peel and flesh puncture strength in the fruit of the relevant varieties of large cranberry. The mean value of peel and flesh puncture strength in the fresh fruit of cranberry was 6.1 N, and after 40 days in storage the value decreased by 2.3 N.
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Abstract

The article addresses the issues falling within the scope of the economic analysis of a detached building’s heating system with a direct evaporation ground source heat pump installation. The paper was elaborated based on the data made available by the investment’s contractor and the investor. The paper provides data on the investment expenditures and utility cost, calculations of the installation payback, internal return rate and the current net value.
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Abstract

The article describes selected issues falling within the scope of the technical analysis of a detached building’s heating system with a direct evaporation ground source heat pump installation. This paper covers the characteristics of modernized facility as well as calculations to determine the heat demand. What is more, the article describes the manner in which heat pumps shall be selected, its installation components as well as the receiving installation.
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Abstract

This article presents the peculiarities and methodical principles for designing the technologies and forms of organization of the construction liquidation cycle for typical unified series of residential buildings. The systematic approach for developing the necessary settings and indicators of the structure of a complex technological process for disassembling, destructing and demolishing of structural elements and buildings in general is given. The multigraph is created for the closed walk model of correlation of the parameters of the organizational and technological solutions of the construction liquidation cycle.
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Abstract

Sapropel deposits are widely distributed around the globe. In the Americas area they are adjacent to the Great Lakes region, in Europe sapropel deposits can be spotted in the territory of Scandinavia, France, Switzerland, Germany, Poland, Belarus, Russia and in the northern regions of Ukraine. Use of sapropel as a fertilizer can enhance high and stable yields of crops. However, despite the proven effectiveness of long-term practical researches in this area, nowadays sapropel is almost not used. One of the reasons - lack of developed processing methods of extraction and processing, including dehydration. Material properties as an object of interaction with the working bodies, change of their settings in the processing are crucial in the choice of technologies, development, bringing up to the necessary parameters and subsequent use. Sapropel high humidity (95-98%) is one of the main factor that determines the quality of its properties after the interaction with working bodies. However, in the process of decreasing, in interaction with oxygen, there are significant changes in physical and mechanical properties of sapropel. Decisive in the direction selection process of lake sapropels’ use in the economic sector is their moisture exchange and thermodynamic parameters. The complexity of setting the water apart, if freshly extracted sapropels possess only 15-20% of it, shows their strong water-retaining capacity. The above mentioned phenomenon proves the need for their use as an organic fertilizer during the crops growing, as superficial loss of moisture in the soil creates a new global problem. On the basis of deep analysis of the sapropels’ properties, the authors suggest three areas of freshly extracted lake sapropel application in mixtures with leafy part of the crops: in biogas production with its further use as an organic fertilizer; making a compost mixture of organic origin which physical and mechanical properties are approximate as that of the soil; alternative solid fuels in the form of briquettes.
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Abstract

An alternative approach of the determining of conditions of safe stability loss of rectilinear motion of a wheeled vehicle model with controlled wheel module in the sense of N.N. Bautin is considered. The slipping forces are presented accurate within cubic expansion terms in the skid angles. Terms and conditions of safe stability loss depend on the ratio between the coefficients of resistance to the skid, the adhesion coefficients in the transverse direction of the axes and the parameter of torsional stiffness of the controlled wheel module. The presented approach to the analysis of real bifurcations related to the divergent loss of rectilinear motion mode stability has a clear geometric pattern: if in the vicinity of rectilinear motion at subcritical speed, there are additionally two unstable circular stationary states, then the stability limit is of dangerous nature in the sense of N.N. Bautin; if two circular stationary modes exist at supercritical speed, the limit of the stability loss in the parameter space of the longitudinal velocity is safe in the sense of N.N. Bautin. Analysis of the number of stationary modes in the vicinity of the critical velocity of rectilinear motion is performed for the obtained determining equation - cubic binomial.
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Abstract

In the article the equations have been worked making it possible to model the motion of freerunning grain mixture flow on a flat sloping vibrating sieve within the framework of shallow water theory. Free-running grain mixture is considered as a heterogeneous system consisting of two phases, one of which represents solid particles and the other one gas. The mixture is brought into a state of fluidity by means of high-frequency vibration imposition. Coefficients of internal and external friction and dynamic-viscosity decrease by exponential law as the fluctuation intensity is increased. When considering grain mixture dynamics, the following assumptions are put forward: we ignore the air presence in space between particles, we consider the density of particles to be constant, the free-running mixture is similar to Newtonian liquid. The basic system of equations of grain mixture dynamics is due to the laws of continuum mechanics. The equation of continuity is issued from the law of conservation of mass, and the dynamic equations are issued from the law of variation of momentum. The stress tensor equals to the sum of the equilibrium tensor and the dissipative tensor. The equilibrium part of the stress tensor is represented by the spherical tensor, which is found to conform to Pascal law for liquids, and the dissipative part, which is responsible for viscous force effect and defined by Navier-Stokes law. Boundary conditions on the surfaces (restricting the capacity of the free-running grain mixture) have been researched. The distributions of apparent density and velocity field are assigned at the inlet and outlet flow sections of the mixture. The normal velocity component of the grain mixture on the side frames and on the sieve becomes zero, which meets the no-fluid-loss condition of the medium through the frame. Beyond that point at this time we satisfy dynamic conditions, which characterize the mixture sliding down the hard frame, motion flow resistance force is represented as average velocity linear dependence. A kinematic condition and two dynamic ones are stipulated on the free surface layer. One of the conditions states mass flow continuity across the free surface, the other one states the stress continuity while passing through the free surface. The basic premise of planned motion equations is the condition of small size of flow depth in comparison with its width. With the use of shallow water theory the basic principles of the equations of flow dynamics are simplified and for their solving a Cauchy problem can be set.
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Abstract

It is shown that heat energy transfer from the source to the medium is accompanied by rheological transitions. Physical parameters of the medium change in the rheological transition zone due to heat energy flow transfer at a certain speed. It is shown that use of linear gradient laws during description of heat energy transfer processes leads to great differences between theoretical and experimental results, as well as the paradox of infinite spreading speed of disturbances of temperature fields. For mathematical description of heat energy transfer processes in mediums, it is proposed to use the method of irreversible rheological transitions and zero gradient, thus providing solutions of nonlinear differential equations in analytical form.
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Abstract

A mathematical model of the process of thermoelastic deformation and dissipative heating of elastomeric structural elements are assumed . The methods of prediction the longevity of structures based on the use of entropy fracture criteria are proposed. For solving of the link thermoelasticity problem of method of successive approximations is used.
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Abstract

The article is devoted to the development of technogenic risk management models and formalization of the process of support in making decision in the sphere of industrial safety. The structural, informative and mathematical models, used to process information in the technological risks management, as well as a formal model of the process of support of making decision in achieving an acceptable level of technical risk are presented and analyzed.
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Abstract

The possibility of producing 3-aminobenzyl alcohol and 3-aminobenzaldehyde by oxidation of 3-aminotoluene with ozone in the solution of acetic anhydrite in the presence of manganese (II) acetate, potassium bromide and sulfuric acid has been shown. The catalytic systems for regulating selectivity and depth of substrate oxidation has been developed. The catalytic system Mn(OAc)₂ – Ac₂0 – H₂SO₄ promotes the formation of alcohol (65.5%) and 3- acetylaminobenzylidendiacetate (20.1%) with the system Mn(OAc)₂ – KBr – Ac₂O – H2SO₄ increases oxidation selectivity on the methyl group to 90.8% producing mainly aldehyde (80.8%) The optimum temperature of selective oxidation of 3– aminotoluene with the ozone – air mixture (30°C) which is much lower than that of oxidation by the known methods (120°-240°C) and the optimum rations of the reagents concentrations: for alcohol synthesis – [ArCH3] : [Mn(OAc)₂] : [H₂SO₄] =1 : 0.2 : 2.5; for aldehyde synthesis –[ ArCH3]: [Mn(OAc)₂] : [KBr] aldehyde synthesis – [ArCH3] : [Mn(OAc)₂] : [KBr] : [H₂SO₄] = 1:0.2:2.5 have been determined.
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Abstract

This work is an analysis of construction and creation of a 3D model of a wind turbine blade in a CAD environment, using SOLIDWORKS on the basis of forces influencing the blade, which were determined using WIATRAK 1.1 software. The presented process is related to the issues of 3D modelling of a wind turbine blade and simulation of fabrication process in the CAM environment.
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Abstract

The flow of a viscous incompressible fluid in small gaps hydraulic devices and devices based on the hop boundary changes in viscosity. For the distribution model adopted dynamic viscosity was integrate the equations of fluid motion, whereby expressions are obtained for the velocity of the liquid height of the gap. The expressions for calculation of the fall capacity flow section are determined. Examples of the calculation of distributions velocity and falling bandwidth to a narrow gap are given.The estimation of the limits of applicability of classical approach to the calculation of viscous flow in micro gap is executed.
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