A review of models for investigating the behaviour of nitrogen in soil

1982 ◽  
Vol 296 (1082) ◽  
pp. 341-349 ◽  
Keyword(s):  
Organic Matter ◽  
Mathematical Models ◽  
Nitrogen Cycle ◽  
Statistical Treatment ◽  
Scientific Understanding ◽  
Data Series ◽  
Transport Models ◽  
Management Models

An efficient way to integrate knowledge on the behaviour of nitrogen in soil is by the development of mathematical models. Models are developed for several aims, such as prediction, management or scientific understanding. Prediction and management models are mainly based on a statistical treatment of data series from preceding years. Models that have been made to obtain a better understanding of the nitrogen cycle are usually based on a mechanistic description of processes such as leaching, volatilization of ammonia, mineralization, immobilization, nitrification, denitrification and uptake by the roots. Differences between models occur because these processes are described with varying degrees of sophistication; often, the description of one or two of the processes dominate the entire model. Thus, a classification of models can be based on the processes that are emphasized. A useful categorization distinguishes between transport models, organic matter models and soil-plant relation models.

scholarly journals A comprehensive review of sucker rod pumps’ components, diagnostics, mathematical models, and common failures and mitigations

2021 ◽  
Author(s):  
Sherif Fakher ◽  
Abdelaziz Khlaifat ◽  
M. Enamul Hossain ◽  
Hashim Nameer
Keyword(s):  
Mathematical Models ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Gas Industry ◽  
Holistic View ◽  
Comprehensive Review ◽  
Artificial Lift ◽  
Sucker Rod ◽  
Sucker Rod Pump

AbstractIn many oil reservoirs worldwide, the downhole pressure does not have the ability to lift the produced fluids to the surface. In order to produce these fluids, pumps are used to artificially lift the fluids; this method is referred to as artificial lift. More than seventy percent of all currently producing oil wells are being produced by artificial lift methods. One of the most applied artificial lift methods is sucker rod pump. Sucker rod pumps are considered a well-established technology in the oil and gas industry and thus are easy to apply, very common worldwide, and low in capital and operational costs. Many advancements in technology have been applied to improve sucker rod pumps performance, applicability range, and diagnostics. With these advancements, it is important to be able to constantly provide an updated review and guide to the utilization of the sucker rod pumps. This research provides an updated comprehensive review of sucker rod pumps components, diagnostics methods, mathematical models, and common failures experienced in the field and how to prevent and mitigate these failures. Based on the review conducted, a new classification of all the methods that can fall under the sucker rod pump technology based on newly introduced sucker rod pump methods in the industry has been introduced. Several field cases studies from wells worldwide are also discussed in this research to highlight some of the main features of sucker rod pumps. Finally, the advantages and limitations of sucker rod pumps are mentioned based on the updated review. The findings of this study can help increase the understanding of the different sucker rod pumps and provide a holistic view of the beam rod pump and its properties and modeling.

Classification of Mathematical Models for Process Design

2021 ◽  
Vol 41 (11) ◽  
pp. 1045-1048
Author(s):  
S. Yu. Kalyakulin ◽  
E. V. Mitin ◽  
S. P. Sul’din
Keyword(s):  
Mathematical Models ◽  
Process Design

scholarly journals Timescales for the development of methanogenesis and free gas layers in recently-deposited sediments of Arkona Basin (Baltic Sea)

2012 ◽  
Vol 9 (5) ◽  
pp. 1915-1933 ◽  
Author(s):  
J. M. Mogollón ◽  
A. W. Dale ◽  
H. Fossing ◽  
P. Regnier
Keyword(s):  
Organic Matter ◽  
Baltic Sea ◽  
Reactive Transport ◽  
Reaction Pathway ◽  
Organic Matter Degradation ◽  
Muddy Sediment ◽  
Transport Models ◽  
Methane Gas ◽  
Geochemical Profiles ◽  
Arkona Basin

Abstract. Arkona Basin (southwestern Baltic Sea) is a seasonally-hypoxic basin characterized by the presence of free methane gas in its youngest organic-rich muddy stratum. Through the use of reactive transport models, this study tracks the development of the methane geochemistry in Arkona Basin as this muddy sediment became deposited during the last 8 kyr. Four cores are modeled each pertaining to a unique geochemical scenario according to their respective contemporary geochemical profiles. Ultimately the thickness of the muddy sediment and the flux of particulate organic carbon are crucial in determining the advent of both methanogenesis and free methane gas, the timescales over which methanogenesis takes over as a dominant reaction pathway for organic matter degradation, and the timescales required for free methane gas to form.

scholarly journals Mathematical Modeling of Main Classes of Stochastic Productive Systems

2019 ◽  
Vol 29 (4) ◽  
pp. 496-509
Author(s):  
Alexander A. Butov ◽  
Maxim A. Volkov ◽  
Viktor N. Golovanov ◽  
Anatoly A. Kovalenko ◽  
Boris M. Kostishko ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Time Distribution ◽  
Just In Time ◽  
Birth And Death Processes ◽  
Multistage System ◽  
Martingale Methods ◽  
Time Class ◽  
Productive Systems ◽  
Time Systems

Introduction. The article deals with mathematical models of two main classes of processes in stochastic productive systems. For a multistage system, conditions of belonging to a “just-in-time” class or a class with infinite support of the time distribution function for productive operations are determined. Materials and Methods. Descriptions and investigations of models are carried out by trajectory (martingale) methods. For “just-in-time” systems and multistage stochastic productive systems, terms and methods of random walks in a random environment and birth and death processes are used. The results are formulated as descriptions of intensity characteristics of equalizers of point counting processes. Results. Two theorems are given and proved; they justify the proposed classification of the mathematical models of productive systems. The criteria of the belonging of the stochastic productive system to the class “just-in-time” are given. A theorem on the incompatibility of groups of “just-in-time” systems and systems infinite support of the time distribution for operations is proved. Discussion and Conclusion. The results show the feasibility of analyzing stochastic productive systems by martingale methods. The descriptions of terms of intensities of the equalizers time of productive processes admit generalization.

scholarly journals The system of points of view in Vasily Shukshin's short stories

2021 ◽  
Vol 27 (3) ◽  
pp. 148-154
Author(s):  
Natalia A. Guz ◽  
Yulia G. Babicheva
Keyword(s):  
Short Stories ◽  
Scientific Understanding ◽  
Point Of View ◽  
The Other ◽  
Frequent Change ◽  
History Of ◽  
Points Of View ◽  
First Time

The purpose of the work is to explore the point of view in Vasily Shukshin's short stories in its systematic and diverse manifestation. Topicality is provided by the exceptional significance of this category in narratology. The study of the point of view based on the material of short stories by Vasily Shukshin has been conducted for the first time. The article briefly traces the history of scientific understanding of the category of point of view in foreign and Russian philology and notes the variety of approaches and definitions in the formulation of the concept. The authors use the classification of Boris Uspenskij for analysis and consider the point of view in Vasily Shukshin's short stories in psychological, ideological (evaluative), spatial-temporal and phraseological terms. The positions of Boris Korman, Yuri Lotman, Wolf Schmid and Franz Karl Stanzel also take into account. The authors note the features of Vasily Shukshin's narration that affect the expression of the point of view in the text. Vasily Shukshin's short stories are characterised by a dynamic and frequent change of points of view, which indicates the technique of “montageˮ and similarities in this regard with cinematic techniques. The conclusions generalise the variety of ways and forms of expression of the point of view in the studied artistic material. The point of view in the considered stories is characterised by variability in the correlation of subjects of speech and subjects of consciousness, alternation of external and internal points of view, mutual transitions from one to the other, text interference and other hybrid phenomena.

scholarly journals Sanitary and hygienic assessment of working conditions of civil aviation pilots

2021 ◽  
Vol 100 (10) ◽  
pp. 1084-1094
Author(s):  
Igor V. Bukhtiyarov ◽  
Evgeny V. Zibarev ◽  
Nicolay N. Kuryerov ◽  
Oksana V. Immel
Keyword(s):  
Working Conditions ◽  
Statistical Treatment ◽  
Civil Aviation ◽  
Work Intensity ◽  
Local Vibration ◽  
Factors Affecting ◽  
Separate Form ◽  
Legislative Framework ◽  
Aviation Pilots

Introduction. The analysis of working conditions of pilots of civil aviation aircraft has been carried out according to the data of sanitary and hygienic characteristics (SHC). The non-compliances with hygiene standards for several factors have been established at the same time in all SHC. Materials and methods. The 220 SHC of pilots, who had been examined in the clinic of FSBSI RIOH due to suspicion of occupation disease from 2015 to 2019, conducting flights by plane (49%) and helicopter (51%) were analyzed. The methods of account of acoustic load, hygiene assessment and classification of working conditions, peer review methods, and statistical treatment methods have been used. Results. The working conditions, according to the criteria of the Guide R 2.2.2006-05, are assigned to the following classes: 3.2 - in 26%; 3.3 - in 41%; 3.4 - in 33%. Exceeding the permissible equivalent noise levels was recorded at 92% of workplaces. According to SHC, the exceedances were from 1.2 dB to 34.5 dB (class 3.1-3.4). In assessing the work intensity in 83% of cases from 5 to 11 indicators of class 3.2 were recorded. It has determined class 3.3 of work intensity. The levels of general vibration exceeded hygiene standards in 48% of cases (class 3.1- 3.2), local vibration - in 8% (class 3.1-3.2), microclimate parameters - in 67% (class 3.1-3.2), labour severity - in 22% (class 3.1-3.3), less often there were discrepancies in light (6%) and chemical factor (2%). Conclusion. According to a combination of factors, the overall assessment of working conditions of the pilots of civil aviation aircraft in 74% of cases is assigned to classes 3.3-3.4. However, the disadvantages and errors in filling out the SHC can underestimate the degree of harmfulness of the work. To improve the procedure of establishing the connection between the disease, and the profession it is necessary to amend the legislative framework to obtain objective information about the levels of factors affecting pilots, develop a separate form of SHC of working conditions of pilots, detailed instructions about the rules of filling out SHC.

Classification of mathematical models of technological design

2021 ◽  
pp. 68-71
Author(s):  
Keyword(s):  
Mathematical Model ◽  
Mathematical Models ◽  
Technological Process ◽  
Process Design ◽  
Geometric Parameters ◽  
Technological Design ◽  
Technological Processes ◽  
Technological Preparation

The use of mathematical models is of great importance for the automation of the design of technological processes. Representation of the geometric parameters of the part in the form of mathematical models allows automating the development of the structure and calculation of the parameters of the technological process, which is important for the complete digitalization of the technological preparation of production. Keywords: technological process, design, mathematical model, digitalization. [email protected]

Epistemic Opacity

2019 ◽  
pp. 98-131
Author(s):  
Johannes Lenhard
Keyword(s):  
Mathematical Models ◽  
Simulation Models ◽  
Scientific Understanding ◽  
The Other ◽  
Weak Version ◽  
Simulation Based ◽  
Lower Standard ◽  
Epistemic Standards ◽  
Epistemic Opacity ◽  
Experimental Runs

This chapter shows that—and how—simulation models are epistemically opaque. Nevertheless, it is argued, simulation models can provide a means to control dynamics. Researchers can employ a series of iterated (experimental) runs of the model and can learn to orient themselves within the model—even if the dynamics of the simulation remain (at least partly) opaque. Admittedly, such an acquaintance with the model falls short of the high epistemic standards usually ascribed to mathematical models. This lower standard is still sufficient, however, when the aim is controlled intervention in technological contexts. On the other hand, opacity has to be accepted if the option for control is to remain in any way open. This chapter closes by discussing whether epistemic opacity restricts simulation-based science to a pragmatic—“weak”—version of scientific understanding.

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