Theory Of Transport Processes Research Articles

STUDY OF EXPORT FREIGHT FLOWS OF GRAIN FROM UKRAINE

Purpose. After the beginning of the full-scale military aggression of the Russian Federation against our country, most of the logistics chains, including those related to ensuring the export of grain, were disrupted. The current system of transportation is focused on the transportation of grain to the western borders with further transshipment to wagons of the European track, which is a difficult and expensive option. In order to ensure the restoration of full-fledged grain export, it is advisable to conduct research on the origins and volume of grain movement, transportation routes and alternative options. Accordingly, the purpose of the study is to determine the main points of origin and repayment of cargo flows of grain export connections in Ukraine and to determine the direction of improvement of transport and technological lines of grain export from Ukraine in global supply chains. The volumes of car-go flow generation at the railway stations of Ukraine were analyzed. The scientific methods and methods of im-proving the transport and technological lines of grain export are substantiated. Methods. An analysis of literary sources was carried out, which made it possible to establish that the port direction is the main one for grain transportation. The peculiarity of the formation of export grain cargo flows is analyzed. Methods of mathematical statistics, probability theory, theory of sets, theory of algorithms, theory of transport processes and systems, theory of systems are used. It has been established that the distribution of the volumes of seed cargo flows by railway stations of departure in the 2021 / 2022 marketing year is mostly subject to asymmetric distribution laws. The smallest deviation is observed with Cauchy and Gamma distribution approximations. A statistical analysis of wagon flows with grain loads was performed, which allowed us to obtain the following results: the mathematical expectation is 55.8 wagons, the standard deviation is 58.0 wagons, the coefficient of variation is 1.04. Scientific novelty. The scientific novelty obtained as a result of the research to which the article is devoted is the obtained approximate density of the distribution of the volumes of grain cargo flows at the railway stations of departure (on the example of the 2021 / 2022 marketing year). Practical significance. The mathematical expectation and level of correlation of the origin of grain cargo flows at the railway stations of departure are established (on the example of the 2021 / 2022 marketing year). In further studies, the obtained results will be used as initial data for modeling the operation of the grain cargo transportation system in the direction of the western borders, and in the future - in the direction of the Black Sea ports of Ukraine.

RESEARCH OF TRANSPORT SUPPLY OF METALLURGICAL INDUSTRY BY RAILWAY TECHNOLOGICAL ROUTES

Purpose. In the conditions of a full-scale war, ensuring the stable functioning of the national economy is one of the strategic tasks. The functioning of the industrial complex, the availability of jobs and the payment of taxes to the state budget are, among other things, part of ensuring the country's defense capability. One of the main branches of Ukraine's economy is the metallurgical industry, so it needs the implementation of measures to ensure reliable and stable work even in conditions of military aggression, constant risks of air strikes and infrastructure damage. In accordance with this, the purpose of the study is to analyze and determine the structure of cargo flows of technological routes of transport service of metallurgical production (on the example of PJSC «Zaporizhstal»). The dynamics of iron ore (iron ore concentrate) and coking coal (coke) transportation volumes by means of transport were studied. Irregularity was investigated and descriptive statistics of daily volumes of transportation of iron ore (iron ore concentrate) and coking coal (coke) for metallurgical production were performed (on the example of PJSC «Zaporizhstal»). Methods. An analysis of the unevenness of the daily volume of goods received for the needs of a metallurgical enterprise (on the example of PJSC «Zaporizhstal») by technological routes of railway transport was carried out. Methods of mathematical statistics, probability theory, theory of transport processes and systems were used. As a result of the analysis of cargo flows arriving at the enterprise, it was established that the distribution of the daily volume of iron ore arriving at the Zaporizhzhia Live station is subject to symmetrical distribution laws with a relatively low variation of 18.4%. The distribution of the random value of the daily volume of coke intake also indicates a certain symmetry with a fairly high probability (59%), and is approximated by a normal distribution. Scientific novelty. As a result of the conducted research, it was established that the approximate density of the distribution of volumes of iron ore (salt-ore concentrate) and coking coal (coke) for metallurgical production (on the example of PJSC «Zaporizhstal» for 2022). Practical significance. The mathematical expectation and the level of correlation of the volumes of iron ore (iron ore concentrate) and coking coal (coke) supply to metallurgical production are established (on the example of PJSC «Zaporizhstal» for 2022). In the future, the obtained results are planned to be used as input data for a simulation model of the functioning of the transport support system of an industrial enterprise.

DIVERSIFICATION STRATEGY AS A WAY TO INCREASE THE COMPETITIVENESS OF A FREIGHT FORWARDING COMPANY

Topicality. The need of introducing new strategies and services to the activities of freight forwarding companies in order to increase their own competitiveness and maintain their positions in the market in due to the growing number of logistics service providers such as NVOCC (Non-Vessel Operating Common Carrier) the services of traditional freight forwarders and their functional differences become unclear.Aim and tasks. The systematization of diversification`s types of the activities made by freight forwarding companies as a strategic direction of increasing competitiveness in the market of relevant services, determination of diversification strategy`s types and relevant areas of activity made by freight forwarding companies, development of an algorithm for implementing the diversification`s strategy of freight forwarding companies, formation of a management decisions’ list that should accompany the process of diversification freight forwarding companies.Materials and Methods. This scientific research was conducted in accordance with the logic and methodology of system analysis, the theory of transport processes and systems, as well as with the application of operations research methods. The theoretical basis of the study was the works of leading experts in strategic management, diversification of the activities of enterprises and the work of freight forwarding companies. The morphological method was used to substantiate the development directions of transport and forwarding services. Methods of analysis and synthesis were used to structure the process of development of freight forwarding services and to structure the process of development of a transport and forwarding company.Research results. Today freight forwarding companies are the first among all integrators of various transport services, which form certain delivery systems both for single shipments and for long-term transport services of regular deliveries, therefore the need of implementing a diversification strategy in the activities of enterprises is increasing so that the integration processes pass in a fully satisfactory manner. Since freight forwarding companies simply do not provide additional services to the transportation process, but are organizers and coordinators of cargo delivery, the main task of the freight forwarder is to free the cargo owner from solving issues related to cargo transportation. That is why there is a dependency between the range of services that freight forwarding companies can offer and the client's problems that these services can cause. Of course, it is more convenient and profitable for the client to transfer all types of cargo-related work to one company, which will completely take over the organization and implementation of the process without the involvement of third companies. In order for the implemented diversification strategy to bring only competitive advantages and positive consequences to the freight forwarding company, it is necessary to study and analyze the market, the behaviour of competitors, consumers and suppliers when developing a strategy and planning new areas of activity. It is no less important to distinguish the directions the diversification strategy in order for better understanding what goals should be aimed. Only with proper analysis, development of the goals and plans, understanding trends and taking into account possible risks, it is possible to accept the proper and desired results of the implementation of the diversification strategy of freight forwarding companies.Conclusion. Due to the fact that freight forwarding companies today are organizers and coordinators of freight transportation, they need to diversify their activities and range of services to fully satisfy the needs of consumers, which consist in acquiring a complete package of services that could free the cargo owner from solving any kind of issues, related to the transportation of goods. In order for the implemented diversification strategy to bring only competitive advantages and positive consequences to the freight forwarding company, it is necessary to study and analyze the market, the behaviour of competitors, consumers and suppliers when developing a strategy and planning new areas of activity.

Functional model of road safety for motor transport enterprise with account of high environmental temperatures

Introduction. The accident rate in road transport in the summer period of the year in conditions of high ambient temperatures has a steady upward trend. The main reasons for this situation are changes in the condition of drivers and the low efficiency of the climate systems of some vehicles. Motor transport enterprises take into account the conditions of the external environment in their activities and adjust the technology of the transport process. Such environmental conditions are ice, fog, precipitation, low air temperature and others. However, high ambient temperature is not included in such a list. In this regard, the study of the features of the functioning of a motor transport enterprise in conditions of high ambient temperatures and the development on this basis of a functional model for ensuring road safety is an urgent task.The purpose of this work is to improve the safety of road transport on the basis of the development of a functional structure of the road safety service of a motor transport enterprise, taking into account the high ambient temperature.Methods. The work is based on the synthesis of general scientific research methods, which included the provisions of system analysis, as well as the provisions of the theory of transport processes, the technical operation of vehicles.Results. The result of the work was the developed functional model of the road safety service of a motor transport enterprise, according to which the road safety service is endowed with control and administrative functions in relation to the activities of the personnel service, technical service and operation service on issues related to road safety. This model differs from the known ones in that it contains functions for responding to high ambient temperatures. An algorithm has been developed for the functioning of the traffic safety service in conditions of high ambient temperature, which prevents its influence on the increase in the aggressiveness of driving cars and the low efficiency of the climate systems of a part of vehicles. These provisions constitute the scientific novelty of the work.Discussion and conclusion. The practical value of the work lies in the improvement of the tools of the motor transport enterprise, aimed at preventing an increase in the accident rate in conditions of high ambient temperatures.

ESTIMATION OF THE TIME OF THE VESSEL'S ARRIVAL AT PORT

Purpose. The paper aims at the assessment of the probability of the vessel’s arrival at the port at a specified time interval considering the different combination of the voyage charter-party (C/P) terms and their wordings. Methodology. The structure of the vessel's time in port was formed considering the C/P terms and their wordings. The time intervals for which it is actual to estimate the time of arrival were defined on the basis of the theory of transport processes and systems. The normal distribution law was used to estimate of the probability of a vessel's arrival at a port at a specified time interval. Findings. The probability of the vessels arrival at the port of loading in the C/P in question was searched in three most actual situations: 1) the vessel's opening date is known; 2) the vessel's arrival to the port of discharging on previous C/P is known and 3) the vessels position on the passage to the port of discharging in previous voyage is known. For these three situation were estimate the probability of the duration of the time elements from the opening point and present position points to the port of loading in the C/P in question far as the C/P terms indicate the beginning the duration of the laytime. Originality. For the first time the vessel's time in port was structured considering the C/P terms and their possible wordings, their impact on the time in port was determined, and the probability of vessel's arrival at specified time intervals was searched. Practical value. The obtained results can be used in voyage planning (during fixing the C/P and further voyage performance) by estimation the duration of the time in port considering the C/P terms and wordings of the beginning and duration of laytime and time of the vessel's arrival.

Scavenging of radioactive gases due to adsorption by atmospheric nanoaerosols

We analyze an influence of radioactive decay and kinetic effects on the rate of trace gas scavenging due to adsorption by an ensemble of solid porous nanoparticles. The size of nanoparticles is comparable to the mean free path in the air at normal conditions. We employ a transient model of adsorption of radioactive gases by an ensemble of porous particles. Our analysis applies a flux-matching theory of transport processes in gases and assumes constant thermophysical properties of the gases and particles. It is demonstrated that evolution of concentration of adsorbed gas inside particles is determined by an ordinary differential equation of the first order. Calculated temporal dependences of adsorbed amount of radioactive gas by particles are compared with experimental results of Noguchi et al. (Jpn J Health Phys 25:209–219, 1990) for gaseous Iodine-131 adsorption by carbon-based atmospheric nanoaerosols. We also showed that when an approximation of uniform distribution of concentration of adsorbed gas inside particles is not valid, temporal evolution of concentration of an active trace gas in a gaseous phase is governed by an integro-differential equation.

Introduction: Review of the Main Principles of the Unified Nonlocal Theory of Transport Processes

Introduction: Review of the Main Principles of the Unified Nonlocal Theory of Transport Processes

Light-induced phenomena in one-component gas: The transport phenomena

The article presents the theory of transport processes in a one-component gas located in the capillary under the action of resonant laser radiation and the temperature and pressure gradients. The expressions for the kinetic coefficients determining heat and mass transport in the gas are obtained on the basis of the modified Boltzmann equations for the excited and unexcited particles. The Onsager reciprocal relations for cross kinetic coefficients are proven for all Knudsen numbers and for any law interaction of gas particles with each other and boundary surface. Light-induced phenomena associated with the possible non-equilibrium stationary states of system are analyzed.

Introduction: Review of the Main Principles of the Unified Nonlocal Theory of Transport Processes

Introduction: Review of the Main Principles of the Unified Nonlocal Theory of Transport Processes

Theory of transport processes in wood below the fiber saturation point. Physical background on the microscale and its macroscopic description

Abstract The macroscopic formulation of moisture transport in wood below the fiber saturation point has motivated many research efforts in the past two decades. Many experiments demonstrated the difference in steady state and transient moisture transport and the inadequacy of models derived for steady state transport when used to describe transient processes. A suitable modeling approach was found by distinguishing between the two phases of water in wood, namely bound water in the cell walls and water vapor in the lumens. Such models are capable of reproducing transient moisture transport processes, but the physical origin of the coupling between the two phases remains unclear. In this paper, the physical background on the microscale is clarified and transformed into a comprehensive macroscopic description, ending up with a dual-scale model comprising three coupled differential equations for bound water, water vapor, and internal energy, as well as a simplified microscale model for determination of the coupling term.

Generalized Quantum Hydrodynamics and Principles of Non-Local Physics

This paper addresses the fundamental principles of generalized Boltzmann physical kinetics, as a part of non-local physics. It is shown that the theory of transport processes (including quantum mechanics) can be considered in the frame of unified theory based on the non-local physical description. Generalized Boltzmann physical kinetics leads to the strict approximation of non-local effects in space and time and after transmission to the local approximation leads to parameter of non-locality T, which on the quantum level corresponds to the uncertainty principle time-energy. Schrodinger equation is consequence of the Liouville equation as result of the local approximation of non-local equations. Generalized quantum hydrodynamics leads to Schrodinger equation as a deep particular case of the generalized Boltzmann physical kinetics and therefore of non-local hydrodynamics. Generalized quantum hydrodynamics can be used for solution of fundamental problems in nanoelectronics.

Molecular theory of barycentric velocity: Monatomic fluids

The notion of barycentric velocity appears in irreversible thermodynamics and fluid mechanics, in which it is a field variable obeying the hydrodynamic equations or, more specifically, the momentum balance equation, which is coupled to the rest of hydrodynamic equations. Therefore, its behavior is not known until the hydrodynamic equations are solved for the flow problem of interest. Unlike diffusion fluxes, heat fluxes, or stresses, it does not have its own constitutive relation similar to Fick's law, Fourier's law, and Newton's law of viscosity. In this work, the constitutive equation is derived for it. In parallel to the phenomenological notion of barycentric velocity, the notion of mean fluid velocity appears in statistical mechanics of irreversible dynamic processes according to the theory of Irving and Kirkwood [J. Chem. Phys. 18, 817 (1950)], and plays the same role of the phenomenological counterpart. In this work, we investigate the statistical mechanical meanings of the mean fluid velocity of a fluid in flow beyond its formal connection with the barycentric velocity. We show that it consists of two components; the center-of-gravity velocity of the packet of fluid molecules, which may be identified with the barycentric velocity in the phenomenological theory, and the diffusive contribution of its collective modes relative to the center of gravity. If the fluid is uniform in space or if the packet of fluid mass is rigid, the diffusive component vanishes. The statistical mechanical (molecular theory) formula for the mean fluid velocity provides the constitutive relation for it in terms of density and temperature gradients present in the fluid in flow. The constitutive relation obtained for the mean fluid velocity can be an important component in the theory of transport processes in liquids. Its significance to fluid mechanics is briefly discussed.

Probabilistic Theory of Transport Processes with Polarization

We derive a probabilistic representation for solutions of matrix-valued transport equations that account for polarization effects. Such equations arise in radiative transport for the Stokes parameters that model the propagation of light through turbulent atmospheres. They also arise in radiative transport for seismic wave propagation in the earth's crust. The probabilistic representation involves an augmented scalar transport equation in which the polarization parameters become independent variables. Our main result is that the linear moments of the augmented transport equation with respect to the polarization variables are the solution of the matrix-valued transport equation. The augmented scalar transport equation is well suited to analyzing the hydrodynamic regime of small mean free paths. It is also well suited to getting approximate solutions by Monte Carlo simulation.

Short-time dynamics of colloidal suspensions.

We report numerical simulations of the velocity autocorrelation function ~VACF! for tagged particle motion in a colloidal suspension. We find that the asymptotic decay follows the theoretical expression for the VACF of an isolated particle, but with the suspension viscosity replacing the pure fluid viscosity ~at long times the suspension behaves, so far as a tagged particle is concerned, like a fluid with the suspension viscosity—as an ‘‘effective fluid’’ !. While physically appealing, this observation is hard to reconcile with a recent theoretical prediction that at long times the VACF in a suspension should be the same as the VACF at infinite dilution. It also differs, in a rather subtle manner, from a scaling rule which has been used in the analysis of experimental and computer simulation results. From the scaling behavior of the VACF we conclude that effective fluid behavior only occurs on a time scale somewhat longer than the time taken for transverse momentum to diffuse a particle radius. This contrasts with the findings of earlier workers who concluded that effective fluid behavior is already observed at much shorter times. @S1063-651X~96!03909-8# A colloidal suspension can be considered as a mixture in which the particles of one component are much bigger than those of all the others. If the size difference is sufficiently large, the smaller components can be thought of as forming fluid which occupies the space between the big particles. The larger particles are often referred to as Brownian particles, named after the botanist Robert Brown, who was the first to observe the apparently random motion of small particles suspended in water. Starting with Brown’s observation, our understanding of these systems has evolved in an interesting series of historical jumps. It was not until over seventy years later that Einstein @1# proposed that the motion of the Brownian particles ~Brownian motion! arose from the accumulated effects of individual collisions between Brownian particles and the particles of the host fluid. This was strong evidence that fluids were molecular in nature, a view not universally accepted at that time. Einstein was also able to make progress with the theory of transport processes in Brownian suspensions. First he derived the expression for the diffusion coefficient D0 of a spherical particle in the dilute limit @2#

Low-temperature transport and quantum interference of ballistic particles in systems with random rough walls

We present a simple theory of transport processes and quantum interference and localization effects in films and channels with rough walls.

Theory of self diffusion in electrolytes

Starting from the concept of marked ions, the problem of self diffusion in electrolyte solutions is discussed from the point of view of irreversible thermodynamics and statistical mechanics. On the basis of the diffusion approach to the theory of transport processes in electrolytes, we derive the statistical theory of self diffusion and an expression for the self diffusion coefficient in terms of the radial distribution function. Results for the concentration dependence of the self-diffusion coefficient are presented.

Theory of Transport Processes

AbstractThis review focuses on the transport of matter and angular momentum in the radiative zones of stellar interiors. The two main causes of such transport are the convective overshooting in the vicinity of convection zones, and the slow motions (meridional circulation and turbulence) due to the rotation of the star. In addition, momentum can be transfered through waves (generated by the motions above) and through magnetic stresses. The characteristics of those processes are examined, with special emphasis on turbulent diffusion.

Toward a theory of transport processes in Brownian suspensions

Fluctuations in dispersed phase concentration increase the particle gradient diffusion coefficient and the effective viscosity of the suspension.

Overview of transport processes of high-energy alpha particles in tokamaks

In this paper the theory of transport processes of high-energy (nonthermalized) alpha particles in tokamak reactors is reviewed. The classical transport processes are investigated. Anomalous transport is considered. The analysis of classical transport is detailed because theoretical predictions of anomalous transport are less reliable.

Theory of transport processes in single crystal growth from the melt

AbstractThe quality of large semiconductor crystals grown from the melt for use in electronic and optoelectronic devices is strongly influenced by the intricate coupling of heat and mass transfer and melt flow in growth systems. This paper reviews the present state of understanding of these processes starting from the simplest descriptions of solidification processes to detailed numerical calculations needed for quantitative modeling of processing with solidification. Descriptions of models for the vertical Bridgman‐Stockbarger and Czochralski crystal growth techniques are included as examples of the level of understanding of industrially important methods.