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.

Narrower System Reliability Bounds With Incomplete Component Information and Stochastic Process Loading

2017 ◽  
Vol 17 (4) ◽  
Author(s):  
Yao Cheng ◽  
Daniel C. Conrad ◽  
Xiaoping Du
Keyword(s):  
System Reliability ◽  
Operating Conditions ◽  
Reliability Estimation ◽  
Design Stage ◽  
Shared Environment ◽  
Limited Information ◽  
Reliability Bounds ◽  
Component Design ◽  
Wide Range ◽  
Stochastic Load

Incomplete component information may lead to wide bounds for system reliability prediction, making decisions difficult in the system design stage. The missing information is often the component dependence, which is a crucial source for the exact system reliability estimation. Component dependence exists due to the shared environment and operating conditions. But it is difficult for system designers to model component dependence because they may have limited information about component design details if outside suppliers designed and manufactured the components. This research intends to produce narrow system reliability bounds with a new way for system designers to consider the component dependence implicitly and automatically without knowing component design details. The proposed method is applicable for a wide range of applications where the time-dependent system stochastic load is shared by components of the system. Simulation is used to obtain the extreme value of the system load for a given period of time, and optimization is employed to estimate the system reliability bounds, which are narrower than those from the traditional method with independent component assumption and completely dependent component assumption. Examples are provided to demonstrate the proposed method.

Experimental Study of Thermal Performance and Pressure Drop in Compact Heat Exchanger Installed in Automotive

2006 ◽  
Author(s):  
M. H. Saidi ◽  
A. A. Mozafari ◽  
A. R. Esmaeili Sany ◽  
J. Neyestani
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Operating Conditions ◽  
Design Stage ◽  
Practical Usefulness ◽  
Experimental Prediction ◽  
Wide Range

In this Study, radiator performance for passenger car has been studied experimentally in wide range of operating conditions. Experimental prediction of Nusselt number and heat transfer coefficient for coolant in radiator tubes are also performed with ε–NTU method. The total effectiveness coefficient of radiator and heat transfer coefficient in air side is calculated via try and error method considering experimental data. The Colburn factor and pressure drop are also estimated for this heat exchanger. Examples of application demonstrate the practical usefulness of this method to provide empirical data which can be used during the design stage.

2. The different types of trust

2018 ◽  
Author(s):  
Richard Clements ◽  
Ademola Abass
Keyword(s):  
Modern World ◽  
Family Wealth ◽  
Wide Range ◽  
The Family ◽  
Different Types ◽  
Complete Series ◽  
Explanatory Text ◽  
The Many ◽  
Primary Materials

Titles in the Complete series combine extracts from a wide range of primary materials with clear explanatory text to provide readers with a complete introductory resource. This chapter examines the different types of trust, how they are used, and the nature of a trust. The many uses of trusts in the modern world, from pensions to the ownership of the family home and the preservation of family wealth are explained. The discussions cover the meanings of trust and property; what trusts are used for; what an equitable interest is; classification of trusts; resulting trusts; constructive trusts; implied trusts; Quistclose-type trusts; and wills and intestacies.

A Study of the Performance of Inertia Air Filters

1969 ◽  
Vol 184 (3) ◽  
pp. 166-174
Author(s):  
D. E. Gee ◽  
B. N. Cole
Keyword(s):  
Performance Testing ◽  
Operating Conditions ◽  
Design Stage ◽  
Small Scale ◽  
Operating Characteristics ◽  
Test Rig ◽  
Fundamental Study ◽  
Air Filters ◽  
Test Programme ◽  
Wide Range

This paper presents an experimental and theoretical study of the design and performance of inertia air filters, with particular reference to rail traction duty. Using a specially constructed test rig, performance testing of commercially available filters was carried out over a wide range of operating conditions. Subsequently, a more fundamental study of some design variables was carried out in a small-scale test rig. The testing was supported by a theoretical approach using a digital computer model of the inertia filtration process. The results of the work indicate that the inertia filter is suited to high-volume, low pressure drop applications. However, operational difficulties, owing to dust build-up occurring within the filter and variations of bleed ratio, may be encountered. The theoretical model was shown to reproduce all the major operating characteristics of the filters measured in the test programme, and to respond to design changes in a similar way to that indicated by earlier published work. A hypothesis of the mechanism of separation is proposed, and it is suggested that the performance of new filter layouts can be examined at the design stage. Supporting work describes the selection, measurement, and production of a suitable range of polydisperse solids for the test programme.

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.

Engine Variables Affecting the SI Engine Knock

2001 ◽  
Author(s):  
Mansoor Karimifar
Keyword(s):  
Pressure Fluctuations ◽  
Careful Analysis ◽  
Operating Conditions ◽  
Design Stage ◽  
Control Loops ◽  
Numerical Result ◽  
Crank Angle ◽  
Wide Range ◽  
General Aspects ◽  
Experimental Findings

Abstract To program the automatic performance control loops of the modern cars at the design stage, numerical result of engine variables effecting knock intensity is the most important tool. Although general aspects of the effect of engine operating conditions on knock have been studied in previous investigations, precise numerical results of that, are not available. The procedures proposed in the past to provide the requirements of the models either predicting or measuring knock are complicated and the details are not presented. In the current work, on the basis of the ‘sampling frequency theorem’ and in regard to the measured frequency of the knocking-pressure fluctuations, a fast on-line data acquisition system was designed and developed. The system was used on a variable compression ratio research engine using two different fuels. Large number of the engine pressure crank angle data were recorded at different operating conditions. Knock, intensity measurement was carried out using a developed criteria obtained by a careful analysis of pressure oscillations at 0.25 degree crank angle intervals. This lead to identification of cycles having specified knock intensity over a wide range of operating conditions. Effect of engine variables on knock intensity was therefore measured numerically for both fuels. Using the simple criteria to study the effect of engine operating conditions on the intensity of knock produced the results which agreed with the earlier experimental findings.

scholarly journals DEVELOPMENT OF THE NUMERICAL METHODOLOGY FOR THE ESTIMATION OF RESONANT PROCESSES AT GASTURBINE ENGINE FLOW DUCT

2020 ◽  
pp. 12-19
Author(s):  
Nikolay Shuvaev ◽  
◽  
Aleksandr Siner ◽  
Ruslan Kolegov ◽  
◽  
...  
Keyword(s):  
High Pressure ◽  
Unsteady Flow ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Design Stage ◽  
High Pressure Compressor ◽  
Wide Range ◽  
Resonant Processes ◽  
Flow Duct ◽  
Pressure Compressor

Ensuring safety of flights is the most important task that is being solved in the process of designing an aircraft engine and aircraft. The most complex are the physical processes occurring inside the aircraft engine, especially in its gas generator: combustion chamber, high-pressure compressor and high-pressure turbine. The unsteady flow of gas in the flow duct of the aircraft engine is very complex, it is difficult to model, because the flow is characterized by a wide range of time and space scales. Unsteady flow in a high-pressure compressor can cause surge and breakdown of the compressor and the entire engine as a whole. Along with the detachment flows causing the surge, in the flow duct there can be resonant phenomena associated with the propagation of powerful sound waves along the flow duct of the engine, which, when a direct and reflected wave is imposed, create a very powerful standing wave that affects the structure. With a certain combination of conditions, the coincidence of the natural frequencies of the oscillations of the air volume and the solid body, such resonant processes in the flow duct of the gas turbine engine can lead to serious breakdowns, such as breakage of rotor blades and guide vanes, destruction of the aeroengine framework and other. The main difficulty is that it is problematic to identify such processes at the design and debugging stage, since there are no suitable mathematical models, and for experimental verification it is required to withstand the specific operating conditions of the node that are not known in advance. This work is devoted to the creation of a calculation technique that will allow in the future to diagnose resonance phenomena at the design stage and thereby significantly reduce the costs for the design, testing and manufacture of an aircraft engine. The proposed technique is based on the nonstationary Navier-Stokes equations for a compressible gas.

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 %.

Development of Diagnostic Tools for Real Time Assessment of Gas Turbine Hot Gas Path Component Temperatures: A Preliminary Study

2002 ◽  
Author(s):  
Carlo Carcasci ◽  
Bruno Facchini ◽  
Francesco Grillo ◽  
Erio Benvenuti ◽  
Gianni Mochi
Keyword(s):  
Gas Turbine ◽  
Evaluation System ◽  
Information Needs ◽  
Effective Means ◽  
Operating Conditions ◽  
Design Stage ◽  
Diagnostic Tools ◽  
Hot Gas ◽  
Path Component ◽  
Wide Range

This paper outlines a part of the work under way at GE Oil and Gas – Nuovo Pignone to develop advanced diagnostic tools to evaluate gas turbine hot gas path components life on the basis of actual operating data continuously recorded by remote monitoring systems. The system aims at correlating component metal temperatures and stresses as a function of operating performance data measured through standard machine instrumentation. Monitored data is processed by a new inverse-cycle algorithm to evaluate gas-path temperatures and pressures. The generated gas path information needs then to be correlated to metal temperatures and stresses with precision suitable for input to algorithms evaluating creep, oxidation and hot corrosion damage. Typically, calculations of gas path data to metal temperatures and stresses are performed at the design stage for a limited number of critical operating conditions by using complex and sophisticated CFD and structural/thermal analysis computer codes. For applications to diagnostic, direct use of such tools for any monitored sets of data would be impracticable. On the other hand, they represent the most effective means for assessing hot gas path component temperatures with adequate accuracy, particularly on last generation engines with substantial turbine blade and nozzle cooling. The approach chosen and described herein consists in extensively using high level design tools over a wide range of turbine operating conditions and use the results to produce equations and maps linking field monitored data to component temperatures suitable for easy implementation into a life evaluation system. In the paper major aspects of the above work are reviewed and synthesized, and significant steps in the first application to a turbine first stage cooled blade are illustrated.

Real-Time Adaptive Modeling Approach to Compensate the Thermal Deformation of Nonlinear Machine Tool Structures

2004 ◽  
Author(s):  
S. Fraser ◽  
Helmi Attia ◽  
M. O. M. Osman
Keyword(s):  
Machine Tool ◽  
Temperature Measurement ◽  
Real Time ◽  
Thermal Deformation ◽  
Operating Conditions ◽  
Design Stage ◽  
Frequency Noise ◽  
Adaptive Modeling ◽  
Wide Range ◽  
Machine Tool Structures

Machine tool structures cannot be fully optimized at the design stage to cover the wide range of operating conditions. Therefore, reliable control systems emerge as the logical solution to compensate for thermal errors. Due to the difficulty of measuring the relative thermal displacement δ between the tool and the workpiece during machining, δ has to be accurately estimated in real-time. A new concept of adaptive modeling is introduced to develop control-based dynamic models to predict and compensate for thermal deformation of nonlinear complex machine tool structures. A key element of this approach is to replace the changes in the contact pressures along the joint by fictitious contact heat sources FCHS. This allows us to track the system nonlinearity through temperature measurements and real-time inverse heat conduction IHCP solution. The proposed approach dealt successfully with a number of challenges; namely, the non-uniqueness of the problem, and the lack of sufficient conditions to identify each of such unusual FCHS separately. The results showed that the models are capable of satisfying the accuracy, stability and computational efficiency requirements, even when the temperature measurement signal is contaminated with random noise. The results also showed that the thermal deformation transfer function behaves as low-pass filters, and as such it attenuates the high frequency noise associated with temperature measurement error.

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