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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 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 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

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

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

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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Abstract

This work analyzes the process of construction and manufacturing of a blade used in a wind turbine. The calculation scheme is presented for forces generated on the blade of a wind turbine and parameters are determined of weather conditions in which the designed element would be working. Subsequently, for the chosen aerodynamic profile the characteristics are calculated of its aerodynamic coefficients, which enables the establishing of the angle of attack which impacts the yield of wind engines. The presented process is an introduction to 3D modelling of a wind turbine’s blade and simulation of its creation in a CAM environment.
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Abstract

We consider the manure removal system, which is used in most pig farms being built and reconstructed at present in Ukraine, and it has been discovered that there are major mistakes during the baths construction in the correct geometry and depth, and therefore discusses their rules of operation. If the baths geometry is wrongly executed, for instance, if the slope is made to slant toward the bottom of the tub filler drain pipe, which in itself is unacceptable, or not properly executed in the form of a special pit steps towards the neck drain, and etc., then a number of problems is inherent of its exploitation. The basic requirements for laying fused-pipe is compliance with its slope. The considered equipment must be equipped with pumping stations to pump manure. The pumps for pumping manure: submersible sewage pumps and dry-installed in the mine and long sewage pumps with electric or PTO shaft of a tractor were analyzed. Attention was paid to the designing of modern equipment for the distribution of manure waste into fractions. The classification of manure storage and the basic requirements for their placement and arrangement was carried out, and recommendations are made for the designing of pumping stations, to select pumps for the pumping stations and the design during the modern construction and reconstruction of old pig farms.
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Abstract

The process of wheel - rail interaction is largely determined by dynamic properties of the car, improvement of which is possible by improving design of the bogie and its basic elements. The article analyses and discusses the problems that have arisen in recent years in the course of operation of bogie 18-100. Tribological and mechanical properties of a friction wedge-type oscillation damper are studied.
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Abstract

The paper presents the results of laboratory tests concerning the cutting process of basket willow by means of disc cutting unit. A disc for cutting wood with diameter of 600mm was used in the tests. The influence of plant’s moisture and the rotary speed of the disc of cutting unit on the unitary energy were determined. The most favorable values of the operating parameters of the cutting unit were selected according to the minimum energy requirement in the cutting process of the tested plant.
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Abstract

The article analyses selected aspects of the technology and logistics used to modernise a coal-fired heating plant to switch to woodchips, which is illustrated with a specific investment. The study presents characteristics of the investment’s heat economy before the modernisation, as well as the assumptions and program of the project. Finally, selected effects of the modernisation have been described
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Abstract

The article focuses on selected aspects of the technical and economic analysis of the 0.8 MW agricultural biogas plant. The electrical power, generated in a cogeneration system, fed power to the neighbouring overhead power grid, Węgrów – Sokołów Podlaski, while the heat energy recovered from combustion gases and liquids cooling the engine was used to heat digesters, a residential building, drying room and farm buildings. The planned annual production equals c.a. 6400 MWh per year given the 8000 h of engine operation. The substrates used as input for the digestive chambers were as follows: fermented maize, pig slurry and liquid digestate pulp.
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Abstract

The paper presents a theoretical analysis of the effect of electric car performance characteristics on vehicle energy consumption and driving range. The test object was a Nissan Leaf electric vehicle. The characteristic curves of basic and additional resistance to motion (sum of rolling resistance and air resistance and inertia resistance or grade resistance, respectively) were applied to the model characteristic curve of electric motor torque of the tested vehicle. Based on that, the graphs describing the relationships between vehicle energy consumption and vehicle speed were made (for specific values of car acceleration / acclivity grade) as well as the relations between vehicle driving range and its traction properties. It was concluded that the use of performance characteristics significantly increased the vehicle’s energy consumption and decreased the available vehicle’s driving range.
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