scholarly journals PRINCIPLES OF CREATING A VIRTUAL MULTI-SENSOR SYSTEM FOR RECOGNITION GAS MIXTURES

2020 ◽  
pp. 827-835
Author(s):  
Максим Дмитриевич Корабель ◽  
Илья Владимирович Синёв ◽  
Дмитрий Алексеевич Шикунов ◽  
Никита Александрович Клычков ◽  
Дмитрий Александрович Тимошенко ◽  
...  
Keyword(s):  
Concentration Dependence ◽  
Power Law ◽  
Tin Dioxide ◽  
Operating Mode ◽  
Operating Conditions ◽  
Gas Sensitivity ◽  
Wide Range ◽  
Power Law Exponent ◽  
Dioxide Film

В широком диапазоне концентраций газов различной химической природы (аммиака, ацетона, пропанола и этанола) исследовалась концентрационная зависимость газочувствительности сенсора газа на основе наноструктурированной пленки диоксида олова при различных режимах его работы. Экспериментально показано, что концентрационная зависимость газочувствительности носит степенной характер, показатель степени n различен для разных газовых проб, причем величина показателя степенного закона n зависит от режима работы сенсора и химической природы анализируемой пробы. Изученное явление позволяет распознавать газовые пробы, содержащие пары веществ различной химической природы. Вероятность классификации газовых проб аммиака, ацетона, пропанола и этанола методом ближайших соседей составила более 95 %. The concentration dependence of the gas sensitivity of a gas sensor based on a nanostructured tin dioxide film was studied under various operating conditions in a wide range of concentrations of gases of various nature (ammonia, acetone, propanol, and ethanol). It has been experimentally shown that the concentration dependence of the gas sensitivity is power-law, the exponent n is different for different gas samples, and the value of the power-law exponent n depends on the operating mode of the sensor and the chemical nature of the sample being analyzed. The studied phenomenon makes it possible to recognize gas samples containing vapors of different chemical substances. The probability of classification of gas samples of ammonia, acetone, propanol and ethanol by the method of nearest neighbors was more than 95 %.

scholarly journals Modeling in marine ice engineering

2021 ◽  
Vol 11 (4) ◽  
pp. 557-567
Author(s):  
A.A. Dobrodeev ◽  
◽  
K.E. Sazonov ◽  
Keyword(s):  
Modeling And Simulation ◽  
Operating Conditions ◽  
Design Stage ◽  
Modern World ◽  
Marine Structures ◽  
Modeling Methods ◽  
Wide Range ◽  
Comparative Advantages ◽  
Quantitative Results

In the modern world, it is already difficult to imagine the creation of a significant engineering structure without modeling its external and internal appearance, the operation modeling of the main mechanisms, operating conditions and many other design features and emerging phenomena at the design stage. The paper interprets modeling and simulation as one of the computational methods that allow us to obtain quantitative results when studying ice impact on marine structures, for e.g. icebreakers and transport vessels, platform substructures, hydro-technical installations. In connection with the above, from the existing classification of modeling methods, the authors consider the physical and mathematical ones in the work. They present comparative advantages of both methods in their application in the problems of marine ice engineering, as well as the prospects for their development for solving a wide range of scientific problems aimed at the development of Arctic shipbuilding.

scholarly journals RECOGNITION OF GAS-AIR MIXTURES BY A SINGLE GAS SENSOR BASED ON TIN DIOXIDE NANOWHISKERS

2021 ◽  
pp. 796-801
Author(s):  
Дмитрий Александрович Тимошенко ◽  
Илья Владимирович Синёв ◽  
Вячеслав Владимирович Симаков ◽  
Никита Александрович Клычков
Keyword(s):  
Gas Sensor ◽  
Concentration Dependence ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Tin Dioxide ◽  
Gas Sensitivity ◽  
Reducing Gas ◽  
Time Drift ◽  
Reducing Gases

Нитевидные нанокристаллы диоксида олова были выращены методом физического осаждения из паровой фазы и перенесены на контактную систему методом замороженной капли. Полученные сенсоры обладают газочувствительностью, воздействие паров газов-восстановителей приводит к увеличению их проводимости. Показано, что существует долговременный дрейф проводимости сенсора при воздействии пробы. Исследована концентрационная зависимость чувствительности сенсора к парам этанола, ацетона и пропанол-2 при температуре 300 °С. На основе анализа концентрационных зависимостей проводимости рассчитаны энергии десорбции частиц, а также положения донорных уровней, индуцированных при адсорбции газов-восстановителей, относительно акцепторного уровня кислорода. Показано, что рассчитанные параметры имеют существенно меньший по сравнению с проводимостью временной дрейф. Использование указанных параметров позволяет распознавать газовоздушные смеси, т.е. однозначно отнести одну из трех исследованных проб к её классу. Tin dioxide nanowhiskers were grown by physical vapor deposition and transferred to the contact system by the frozen drop method. The sensors demonstrate gas-sensitivity. Exposing sensors to the atmosphere contained vapors of reducing-gases leads to an increasing of their conductivity. A long-term drift of the sensor conductivity during reducing-gas exposition was shown. A sensitivity response vs concentration for ethanol, acetone, and propanol-2 vapors at temperature 300 °C was investigated. Desorption energies of the particles and the positions of the donor levels induced by adsorption of reducing gases particles were calculated by analysis of the conductivity vs concentration dependence. The calculated parameters had a significantly smaller time drift in comparison with the conductivity. Using of these parameters makes possible to recognize gas-air mixtures: classify the each of three studied samples to one of classes.

scholarly journals Aspects of risk assessment in power-law distributed natural hazards

2004 ◽  
Vol 4 (2) ◽  
pp. 309-313 ◽  
Author(s):  
S. Hergarten
Keyword(s):  
Risk Assessment ◽  
Natural Hazards ◽  
Power Law ◽  
Risk Taking ◽  
Forest Fires ◽  
Damage Function ◽  
Total Risk ◽  
Wide Range ◽  
Power Law Exponent ◽  
Characteristic Scales

Abstract. Risk assessment is mainly based on certain scenarios involving an event of a certain size which is thought to be characteristic for the considered type of hazard. However, many natural hazards extend over a wide range of event sizes, and some of them are even free of characteristic scales. An expression for the risk taking into account various event sizes is derived, and its implications on risk assessment for earthquakes, forest fires, landslides, and rockfalls are discussed. Under simple assumptions on the damage as a function of the event size, it turns out that the total risk is governed by either the small number of large events or the majority of small events. The distinction between these two classes depends on both the power-law exponent of the event size distribution and the damage function. For earthquakes, forest fires, and rockfalls, the total risk is mainly constituted by the largest events, while results are non-unique for landslides.

Systematic Behaviors of ab-plane Pinning Variations in a Practical Length Wire Fabricated by the MOD/RABiTS Process

2010 ◽  
Vol 1254 ◽  
Author(s):  
J. Yates Coulter ◽  
David W. Reagor ◽  
Jeffrey O. Willis ◽  
Terry G. Holesinger
Keyword(s):  
Field Dependence ◽  
Power Law ◽  
Anisotropic Material ◽  
Isotropic Material ◽  
Angle Measurement ◽  
Coated Conductor ◽  
Short Sample ◽  
Angle Data ◽  
Wide Range ◽  
Power Law Exponent

AbstractIn-field critical current Ic variations, detected using a short sample, angular Ic(77K, H=5.2kOe, Angle) measurement on the ends of a 20 m coated conductor tape fabricated by the MOD / RABiTS process, are shown to be variations in the Ic(H) anisotropy that exist on subcentimeter length scales. A Ic(75 K, H, Angle) study was performed on segments cut from the tape where the power law exponent of the field dependence, α, Ic ∼H−α was calculated for Ic(H, Angle) data. Two extrema behaviors, anisotropic and isotropic, were identified. The isotropic material is shown to outperform the anisotropic material for a wide range of fields and angles at T=26 K.

scholarly journals Dehydrogenation of Methylcyclohexane: Parametric Sensitivity of the Power Law Kinetics

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Muhammad R. Usman ◽  
David L. Cresswell ◽  
Arthur A. Garforth
Keyword(s):  
Activation Energy ◽  
Kinetic Model ◽  
Power Law ◽  
Operating Conditions ◽  
Nonlinear Dependence ◽  
Power Law Model ◽  
Parametric Sensitivity ◽  
Heterogeneous Catalytic ◽  
Wide Range ◽  
Kinetics Of

For heterogeneous catalytic reactions, the empirical power law model is a valuable tool that explains variation in the kinetic behavior with changes in operating conditions, and therefore aids in the development of an appropriate and robust kinetic model. In the present work, experiments are performed on 1.0 wt% Pt/Al2O3 catalyst over a wide range of experimental conditions and parametric sensitivity of the power law model to the kinetics of the dehydrogenation of methylcyclohexane is studied. Power law parameters such as order of the reaction, activation energy, and kinetic rate constants are found dependent upon the operating conditions. With H2 in the feed, both apparent order of the reaction and apparent activation energy generally increase with an increase in pressure. The results suggest a kinetic model, which involves nonlinear dependence of rate on the partial pressure of hydrogen and adsorption kinetics of toluene or some intermediate.

scholarly journals Lubrication Regime Classification of Hydrodynamic Journal Bearings by Machine Learning Using Torque Data

Lubricants ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 108 ◽  
Author(s):  
Jakob Moder ◽  
Philipp Bergmann ◽  
Florian Grün
Keyword(s):  
Machine Learning ◽  
Gas Turbines ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Time Range ◽  
Combustion Engines ◽  
Lubrication Regimes ◽  
Lubrication Regime ◽  
Wide Range

Hydrodynamic journal bearings are used within a wide range of machines, such as combustion engines, gas turbines, or wind turbines. For a safe operation, awareness of the lubrication regime, in which the bearing is currently operating, is of great importance. In the current study, highspeed data signals of a torque sensor, sampled with a frequency of 1000 hz in a time range of 2.5 s, obtained on a journal bearing test-rig under various operating conditions, are used to train machine learning models, such as neural networks and logistic regression. Results indicate that a fast Fourier transform (fft) of the highspeed torque signals enables accurate predictions of lubrication regimes. The trained models are analysed in order to identify distinctive frequencies for the respective lubrication regime.

Modeling and Experimental Investigation of Bubble Formation in Shear-Thinning Liquids

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Mohamad Taghi Esfidani ◽  
Mohammad Reza Oshaghi ◽  
Hossein Afshin ◽  
Bahar Firoozabadi
Keyword(s):  
Power Law ◽  
High Speed ◽  
Gas Flow ◽  
Bubble Formation ◽  
Experimental Studies ◽  
Methyl Cellulose ◽  
Operating Conditions ◽  
Wide Range ◽  
Bubble Sizes ◽  
Newtonian Liquids

This investigation presents both theoretical and experimental studies on the size of a growing bubble in power-law non-Newtonian liquids. At first, some previous works on the prediction of bubble size in Newtonian liquids have been extended by considering the balance of forces acting on the bubble at the moment of separation. Predicted bubble sizes were validated against the experimental results for a wide range of operating conditions, including different gas flow rates and needle diameters as well as a wide range of physical properties of the Newtonian liquids. Furthermore, in order to determine the size of the bubbles formed in power-law non-Newtonian liquids with a similar analysis, the effective shear rate of bubble growth was calculated in which the rheological properties of fluid were taken into account and subsequently the viscosity of the fluid was modified. Theoretically obtained bubble sizes for non-Newtonian liquids are in a good agreement with our experimental high-speed video observations of three carboxyl methyl cellulose (CMC) solutions.

Experimental and Numerical Investigation of Gas-Yield Power-Law Fluids in a Horizontal Pipe

2019 ◽  
Author(s):  
Abdalsalam Ihmoudah ◽  
Mohamed M. Awad ◽  
Mohammad Azizur Rahman ◽  
Stephen D. Butt
Keyword(s):  
Power Law ◽  
Two Phase Flow ◽  
Operating Conditions ◽  
Superficial Velocity ◽  
Rheological Parameters ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Power Law Fluids ◽  
Wide Range

Abstract Two-phase flow of gas/yield power-law (YPL) fluids in pipes can be found in a wide range of practical and industrial applications. To improve the understanding of the effects of rheological parameters of non-Newtonian liquids in a two-phase model, experimental and Computational Fluid Dynamics (CFD) investigations of gas/yield power-law fluids in a horizontal pipe were carried out. Two Xanthan gum (XG) solutions at concentrations of (0.05% and 0.10% by weight) were used as the working liquids. The experiments were conducted in a flow loop in a 65-m open-cycle system. The horizontal test section had a diameter of 3 inches (76.2 mm). The transient calculations were conducted using a Volume of Fluid (VOF) model in ANSYS Fluent version 17.2. Slug flow characteristics were recorded and observed by a high-speed digital camera in different operating conditions. The slug velocity and slug frequency were investigated experimentally and numerically, and a comparison of results with empirical relationships found in the literature was performed. We observed that the rheological properties of non-Newtonian phase influence the flow behavior in two-phase flow with increasing XG concentrations. The results of the empirical correlation to measure the slug frequency of a gas/non-Newtonian with considered the rheology of the shear-thinning behaver gave acceptable agreement with numerical measurements at low polymer concentration. The effect of liquid superficial velocity on slug translational velocity at low gas superficial velocity was relatively high.

scholarly journals Method for determining the actual group of classification (mode of operation) of load-lifting cranes

2021 ◽  
Author(s):  
Oleksiy Nyezhentsev
Keyword(s):  
Specific Energy Consumption ◽  
Operating Mode ◽  
Technical Condition ◽  
Operating Conditions ◽  
Safe Operation ◽  
The Real ◽  
Mode Of Operation ◽  
Definition Of ◽  
Actual Classification

The problems which arise during the period of expert inspection of the load-lifting cranes which have fulfilled regulatory lifetime, at definition of their actual group of classification (operating mode) are analyzed. It is established that the actual group of classification (mode of operation) of operated cranes, which is determined by the regulations on labor protection (NPAOP), often does not coincide with the passport modes of operation of cranes. A new method of diagnosing the actual classification group (operating mode) of operated cranes has been developed, which allows taking into account the real modes of their loading and classes of use using the value of specific energy consumption of cranes. The proposed method allows to reliably determining the actual group of classification of cranes that have served the regulatory lifetime, taking into account the real operating conditions of all crane mechanisms and their technical condition for the entire period of operation. This makes it possible to reasonably and qualitatively establish the terms and conditions of further safe operation of cranes.

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