scholarly journals Physical processes simulation in a precision device for liquid samples thermal cycling

2021 ◽  
Vol 2131 (2) ◽  
pp. 022061
Author(s):  
I G Kiselev ◽  
D A Belov
Keyword(s):  
Mathematical Model ◽  
Temperature Change ◽  
Initial Conditions ◽  
Polymerase Chain Reaction Method ◽  
Working Fluid ◽  
Exchange Processes ◽  
Equation Boundary ◽  
Urgent Task ◽  
Precision Temperature ◽  
Precision Device

Abstract An urgent task is the development of devices that provide a precision temperature change. The devices used in the real-time polymerase chain reaction method require not only repeated cyclic temperature changes with high accuracy, but also the temperature gradient minimization over the working fluid. In this article, the modeling of the working processes taking place in the thermal block of the device with the previously proposed thermohydraulic system, which ensures the temperature change together with the Peltier elements, is carried out. A mathematical model is formulated and a differential equation, boundary and initial conditions are substantiated. Numerical methods for solving the mathematical model in the Elcut software were applied. An experimental setup was developed and a study of heat exchange processes in the thermal block of a nucleic acid analyzer with a thermohydraulic system was carried out, confirming the adequacy of the developed mathematical model.

scholarly journals Analysis of the preparation technology of a row seeder for work

2020 ◽  
Vol 193 ◽  
pp. 01035
Author(s):  
A. Yu. Popov ◽  
Noureldin Sharaby ◽  
V.V. Zhurba ◽  
Е.А. Chaika
Keyword(s):  
Mathematical Model ◽  
Graph Theory ◽  
Crop Yields ◽  
Initial Conditions ◽  
Critical Path ◽  
Economic Factors ◽  
Agricultural Crop ◽  
Preparation Technology ◽  
Urgent Task ◽  
Relationship Of

The level of preparation of a row seeder for work and its adaptability to adjustments and settings affects the efficiency of sowing. Analysis of the designs of modern row seeders shows that after-sales service remains a reserve for improving the efficiency of their use, and, therefore, increasing the agricultural crop yields. However, the technologies for the preparation and adjustment row seeders remain poorly understood, and the search for ways to reduce the complexity of maintenance for sowing units is an urgent task. The aim of the study is to build a mathematical model of the technology for checking, adjusting and tuning a row seeder on the basis of graph theory, determining a way to reduce the complexity of servicing maintenance a row seeder in preparation for sowing and justifying a rational way of organizing the seeder setting. Taking into account a number of assumptions and initial conditions, a list of operations for adjusting and setting the seeder is developed. A digraph of a row seeder preparation technology is constructed, which displays the sequence and relationship of the operations of preparation, adjusting and sitting its nodes and mechanisms. The critical path with the greatest time spent on seeder maintenance is determined. The methods for reducing the complexity of maintenance of a row seeder were established and it is recommended that further modernization of the units and mechanisms of the seeder by indicators in terms of suitability for verification, adjustment and setup. The methods of preparing the seeder for work by one performer are considered. The influence of economic factors on the number of performers during maintenance of the seeder before sowing is shown.

A Numerical Study of Unsteady Natural Convection in a Rectangular Enclosure: The Effect of Compressibility

2004 ◽  
Author(s):  
K. M. Akyuzlu ◽  
Y. Pavri ◽  
A. Antoniou
Keyword(s):  
Mathematical Model ◽  
Stokes Equations ◽  
Numerical Study ◽  
Vertical Wall ◽  
Ideal Gas ◽  
Working Fluid ◽  
Two Dimensional ◽  
Algebraic Equations ◽  
Rectangular Enclosure ◽  
Circulation Patterns

A two-dimensional, mathematical model is adopted to investigate the development of buoyancy driven circulation patterns and temperature contours inside a rectangular enclosure filled with a compressible fluid (Pr=1.0). One of the vertical walls of the enclosure is kept at a higher temperature then the opposing vertical wall. The top and the bottom of the enclosure are assumed insulated. The physics based mathematical model for this problem consists of conservation of mass, momentum (two-dimensional Navier-Stokes equations) and energy equations for the enclosed fluid subjected to appropriate boundary conditions. The working fluid is assumed to be compressible through a simple ideal gas relation. The governing equations are discretized using second order accurate central differencing for spatial derivatives and first order forward finite differencing for time derivatives where the computation domain is represented by a uniform orthogonal mesh. The resulting nonlinear equations are then linearized using Newton’s linearization method. The set of algebraic equations that result from this process are then put into a matrix form and solved using a Coupled Modified Strongly Implicit Procedure (CMSIP) for the unknowns (primitive variables) of the problem. A numerical experiment is carried out for a benchmark case (driven cavity flow) to verify the accuracy of the proposed solution procedure. Numerical experiments are then carried out using the proposed compressible flow model to simulate the development of the buoyancy driven circulation patterns for Rayleigh numbers between 103 and 105. Finally, an attempt is made to determine the effect of compressibility of the working fluid by comparing the results of the proposed model to that of models that use incompressible flow assumptions together with Boussinesq approximation.

scholarly journals AGV Brake System Simulation

2019 ◽  
Vol 10 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Daniel Varecha ◽  
Robert Kohar ◽  
Frantisek Brumercik
Keyword(s):  
Mathematical Model ◽  
Input Data ◽  
Initial Conditions ◽  
Brake System ◽  
Disc Brake ◽  
Hydraulic Control ◽  
Stopping Distance ◽  
Braking Force ◽  
Braking Process ◽  
The Mathematical Model

Abstract The article is focused on braking simulation of automated guided vehicle (AGV). The brake system is used with a disc brake and with hydraulic control. In the first step, the formula necessary for braking force at the start of braking is derived. The stopping distance is 1.5 meters. Subsequently, a mathematical model of braking is created into which the formula of the necessary braking force is applied. The mathematical model represents a motion equation that is solved in the software Matlab by an approximation method. Next a simulation is created using Matlab software and the data of simulation are displayed in the graph. The transport speed of the vehicle is 1 〖m.s〗^(-1) and the weight of the vehicle is 6000 kg including load. The aim of this article is to determine the braking time of the device depending from the input data entered, which represent the initial conditions of the braking process.

DIGITAL RUBLE ISSUE

2021 ◽  
Vol 7 (201) ◽  
pp. 80-87
Author(s):  
V.N. Terentyev ◽  
◽  
K.G. Petrov ◽  
Keyword(s):  
Asset Management ◽  
Financial Services ◽  
World Market ◽  
Domestic Economy ◽  
Financial Assets ◽  
Digital Currency ◽  
Exchange Processes ◽  
Urgent Task ◽  
Domestic Legislation ◽  
Financial Infrastructure

The state economies of our time are faced with the urgent task of developing innovative campaigns to address issues of digital financial asset management. This trend is caused by the development of technological systems for providing financial services and products on the world market. The proposed instrument for regulating digital banking is the integration into the domestic economy of a new form of money - the digital currency of the central bank (digital ruble). The purpose of the study is to form an idea about the issue of digital financial assets and, as a result, to develop an effective way to introduce digital financial assets "digital ruble" into the domestic financial infrastructure. The shortcomings of the existing domestic legislation regarding the regulation of exchange processes and regulation of the turnover of digital financial assets are revealed. The concepts of "issue of digital financial assets", "digital ruble" are disclosed. The processes of issuing the digital ruble, the planned turnover in the domestic financial system, the possibility of converting digital financial assets being introduced into cash and non-cash money are considered. The position of the digital ruble in the structure of the domestic money supply is determined. Potential problems in the economic system in the process of integrating the digital ruble into it are noted. The processes of pricing and fixing the value of digital financial assets are considered. The analysis of the issue of digital financial assets showed a technical flaw and a general limitation in the functionality of the digital ruble, which is supposed to be integrated.

Performance Analysis of a Solar-Assisted Organic Rankine Cycle

2020 ◽  
Author(s):  
M. T. Nitsas ◽  
I. P. Koronaki
Keyword(s):  
Mathematical Model ◽  
Performance Analysis ◽  
Temporal Variation ◽  
Storage Tank ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Evaporation Temperature ◽  
Solar Powered ◽  
The Mathematical Model

Abstract The objective of this paper is the thermodynamic analysis of a solar powered Organic Rankine Cycle (O.R.C.) and the investigation of potential working fluids in order to select the optimum one. A dynamic model for a solar O.R.C. with a storage tank, which produces electricity is developed. The mathematical model includes all the equations that describe the operation of the solar collectors, the storage tank, the Rankine Cycle and the feedback between them. The model runs for representative days throughout the year, calculating the net produced energy as a function of the selected evaporation temperature for every suitable working fluid. Above that, the temporal variation of the systems’ temperatures, collectors’ efficiency and net produced power, for the optimum organic fluid and evaporation temperature are presented.

scholarly journals Modeling of greenhouse radiant heating

2018 ◽  
Vol 193 ◽  
pp. 03006 ◽  
Author(s):  
Mikhail Pavlov ◽  
Sergey Lukin ◽  
Oleg Derevianko
Keyword(s):  
Mathematical Model ◽  
Air Temperature ◽  
Mass Exchange ◽  
Thermal Power ◽  
Equation System ◽  
Radiant Heating ◽  
Heat And Mass Exchange ◽  
Heating Systems ◽  
Exchange Processes ◽  
The Impact

Commercially available greenhouses are commonly used for provision of year-round growing of agricultural crops at protected ground. In order to provide favorable conditions for plants growth these agricultural constructions should be equipped by artificial heating systems in cold sea-sons. This work presents an overview of basic traditional and alternative heating systems which find their applications in agriculture. Advantages of application of roof radiant heating with infrared radiation sources for green-houses are discussed. It was discovered that now there is no appropriate mathematical model of greenhouse radiant heating, which takes into account both heat and mass exchange processes. Here we propose a mathematical model of radiant heating, which includes equation system of both heat and mass exchange processes for greenhouse, its enclosure and soil. The numer-ical calculations were performed for commercially available greenhouse “Farmer 7.5”. We investigated the impact of external air temperature and heat exchange rate on the following greenhouse radiant heating characteris-tics: internal air temperature, heating system thermal power and water dis-charge for soil watering.

scholarly journals Review of existing and development of a novel mathematical model for supercritical CO2 cycles working fluid

2018 ◽  
Vol 240 ◽  
pp. 01036
Author(s):  
Marcin Wołowicz ◽  
Jarosław Milewski ◽  
Piotr Lis
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Mathematical Model ◽  
Heat Capacity ◽  
Supercritical Co2 ◽  
Pressure Range ◽  
Critical Conditions ◽  
Working Fluid ◽  
Critical Properties ◽  
Area Of Interest

The paper aims to compare the models of working fluids against experimental data for carbon dioxide close to its critical conditions. Fortunately, most of the work is already done and published where the authors compared the models based on the equation of the state (EoS). There are a few other models which were not investigated, thus we would like to add a few new results here and focus only on near-critical properties where the biggest deviation between experimental and calculated properties can be observed. The area of interest was pressure range of 7.39 – 20 MPa and temperature range of 304-340 K just above fluid critical point (7.39 MPa, 304.25 K). Model validation was performed for density and heat capacity as one of the most important parameters in preliminary cycle analysis.

scholarly journals HFO1234ze(e) As an Alternative Refrigerant for Ejector Cooling Technology

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4045
Author(s):  
Van Vu Nguyen ◽  
Szabolcs Varga ◽  
Vaclav Dvorak
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
The Other ◽  
Coefficient Of Performance ◽  
Fourth Generation ◽  
Working Fluid ◽  
Third Generation ◽  
Alternative Refrigerant ◽  
Overall Performance ◽  
Cooling Technology

The paper presented a mathematical assessment of selected refrigerants for the ejector cooling purpose. R1234ze(e) and R1234yf are the well-known refrigerants of hydrofluoroolefins (HFOs), the fourth-generation halocarbon refrigerants. Nature working fluids, R600a and R290, and third-generation refrigerant of halocarbon (hydrofluorocarbon, HFC), R32 and R152a, were selected in the assessment. A detail mathematical model of the ejector, as well as other components of the cycle, was built. The results showed that the coefficient of performance (COP) of R1234ze(e) was significantly higher than R600a at the same operating conditions. R1234yf’s performance was compatible with R290, and both were about 5% less than the previous two. The results also indicated that R152a offered the best performance among the selected refrigerants, but due to the high value of global warming potential, it did not fulfill the requirements of the current European refrigerant regulations. On the other hand, R1234ze(e) was the most suitable working fluid for the ejector cooling technology, thanks to its overall performance.

A MATHEMATICAL MODEL FOR THE REPRODUCTION DYNAMICS OF TOXOPLASMA GONDII

2015 ◽  
Vol 23 (supp01) ◽  
pp. S91-S100
Author(s):  
JOHN ALEXANDER LEÓN MARÍN ◽  
IRENE DUARTE GANDICA
Keyword(s):  
Mathematical Model ◽  
Partial Differential Equations ◽  
Toxoplasma Gondii ◽  
Epithelial Cells ◽  
Sexual Reproduction ◽  
Numerical Solution ◽  
Definitive Host ◽  
Initial Conditions ◽  
Felis Catus ◽  
One Dimensional

This paper presents a mathematical model describing the reproduction dynamics of the Toxoplasma gondii parasite in the definitive host Felis catus (cat). The dynamics is described by a system of partial differential equations defined in a one-dimensional region, with boundary and initial conditions. The model considers both asexual and sexual reproduction processes of the T. gondii parasite starting from the consumption of T. gondii oocysts from the environment, by the definitive host, and describing the reproduction dynamics until the cat expels infectious oocysts to the environment through its feces. The numerical solution of the system is obtained, and some simulations are made, leaving constant of transition and loss rates, since its variation does not produce significant changes in the reproduction, propagation and creation of new populations; and varying the initial consumption of oocysts from the environment by the cat. It is concluded that, either low or high, the involved populations are always reproduced; they spread by all over epithelial cells and subsequently are expelled to the environment through the cat feces. It is corroborated that the cats are potential multipliers of the oocysts and therefore, the main disseminators of the infection.

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