Blades Forced Vibration Under Aero-Elastic Excitation Modeled by Van der Pol

2017 ◽  
Vol 27 (11) ◽  
pp. 1750166 ◽  
Author(s):  
Ladislav Pust ◽  
Ludek Pesek
Keyword(s):  
Rotor Blade ◽  
Analytical Approach ◽  
Nonlinear Models ◽  
Dynamic Properties ◽  
Deformation Wave ◽  
Response Curves ◽  
Van Der Pol ◽  
External Forces ◽  
Real Type

This paper employs a new analytical approach to model the influence of aerodynamic excitation on the dynamics of a bladed cascade at the flutter state. The flutter is an aero-elastic phenomenon that is linked to the interaction of the flow and the traveling deformation wave in the cascade when only the damping of the cascade changes. As a case study the dynamic properties of the five-blade-bunch excited by the running harmonic external forces and aerodynamic self-excited forces are investigated. This blade-bunch is linked in the shroud by means of the viscous-elastic damping elements. The external running excitation depends on the ratio of stator and rotor blade numbers and corresponds to the real type of excitation in the steam turbine. The aerodynamic self-excited forces are modeled by two types of Van der Pol nonlinear models. The influence of the interaction of both types of self-excitation with the external running excitation is investigated on the response curves.

scholarly journals Evaluation of the energy consumption of container diesel trucks in a container terminal: A case study at Klaipeda port

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110355
Author(s):  
Tomas Eglynas ◽  
Sergej Jakovlev ◽  
Valdas Jankunas ◽  
Rimantas Didziokas ◽  
Jolanta Januteniene ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Dynamic Properties ◽  
Container Terminal ◽  
Superposition Principle ◽  
Critical Parameters ◽  
Container Transportation ◽  
Industrial Emissions ◽  
Transportation Process ◽  
Diesel Trucks

Introduction: In the paper, we examine the energy consumption efficiency of specialized container diesel trucks engaged in container transportation at a seaport terminal. Objectives: Using the container terminal at Klaipėda in Lithuania as the background for the research, we produced an improved energy consumption model for measuring the theoretical energy consumption and regeneration of diesel trucks at the terminal and provide a comparative analysis. Methods: We created a mathematical model which describes the instantaneous energy consumption of the diesel trucks, taking into account their dynamic properties and the overall geometry of their routes—“Ship-Truck-Stack-Ship”—using the superposition principle. We investigated other critical parameters relevant to the model and provide a statistical evaluation of the transportation process using data from a case study of Klaipėda port, where we collected measurements of container transportation parameters using georeferenced movement detection and logs from wireless equipment positioned on the diesel-powered container trucks. Results: The modeling results showed that an instantaneous evaluation of energy consumption can reveal areas in the container transportation process which have the highest energy loss and require the introduction of new management and process control initiatives to address the regulations which are designed to decrease harmful industrial emissions and encourage novel technologies and thereby increase the eco-friendliness of existing systems. Conclusion: Based on the research results, the article can provide a reference for the estimation of diesel truck efficiency in seaport terminal operations.

scholarly journals Horizontal Movement of Fast Ice in the North Water Area

1977 ◽  
Vol 19 (81) ◽  
pp. 547-554 ◽  
Author(s):  
Hajime Ito ◽  
Fritz Müller
Keyword(s):  
Sea Ice ◽  
Water Area ◽  
Physical Characteristics ◽  
Stress Strain ◽  
Horizontal Movement ◽  
The North ◽  
North Water ◽  
Fast Ice ◽  
External Forces

AbstractThe understanding of the horizontal movement of fast ice is important for applied sea-ice mechanics. A case study, carried out in conjunction with a polynya known as North Water, is presented in this paper. The displacements of the fast-ire arches which separate the polynya from the surrounding ice-covered sea, were measured and found to be small. It is, therefore, confirmed that these arches prevent the influx of large quantities of sea ice into the polynya. The results are then explained in terms of the external forces (wind and current), the stress- strain situations and some physical characteristics (temperature and thickness) which were measured simultaneously.

Probabilistic Analysis by Applying Uncertainty Worflows: A Case Study of the Teak Field, East Coast Trinidad

2014 ◽  
Author(s):  
C.J.. J. Segnini ◽  
M.. Rashwan ◽  
M.J.. J. Hernandez ◽  
J. A. Rojas ◽  
M.A.. A. Infante
Keyword(s):  
Reservoir Simulation ◽  
Probabilistic Analysis ◽  
East Coast ◽  
Dynamic Properties ◽  
Large Population ◽  
Model Performance ◽  
Current Standard ◽  
Modeling Software ◽  
Uncertainty Analyses

Abstract This paper presents a methodology for the probabilistic analysis of an infill or step-out opportunity using numerical simulation. Sensitivity and uncertainty analyses for all involved parameters were evaluated through different experimental design techniques. Subsequently, a proxy model was established to reproduce the numerical model performance. Finally, three appropriate solutions were selected from a large population of realizations corresponding to probabilistic percentiles (90%, 50%, and 10% certainty that the specified volume will be recovered). This proposed methodology helped the asset team to evaluate the well candidates more precisely, confidently, and in less time than the current standard methodology. More knowledge about the variables and their effects on overall outcomes was also gained, which helped the team make more-informed decisions. The workflow used the same numerical modeling software, incorporating and facilitating the changes of both static and dynamic properties simultaneously. A case study from Teak field, on the east coast of Trinidad, illustrates the applicability of the methodology and compares its results to those obtained using the standard workflow for the asset. The methodology is one of the latest developments in reservoir simulation, and it has not yet been incorporated into the operator's common practices and procedures for exploitation of the TSP fields.

Comparison of Numerical Methods for Determining Torsion Stiffness of Automotive Chassis

2011 ◽  
Author(s):  
Steven Tebby ◽  
Ebrahim Esmailzadeh ◽  
Ahmad Barari
Keyword(s):  
Finite Element Analysis ◽  
Analytical Approach ◽  
Torsional Stiffness ◽  
Design Stage ◽  
Element Analysis ◽  
Detailed Design ◽  
Vertical Displacements ◽  
Comparison Of The Results ◽  
Torsion Stiffness

The torsion stiffness of an automotive chassis can be determined using an analytical approach based purely on geometry, using an experimental method, or alternatively by employing a Finite Element Analysis (FEA) process. These three methods are suitable at different design stages and combined together could prove to be practical methods of determining the torsion stiffness of a chassis. This paper describes and compares two distinct FEA processes to determine the torsion stiffness of an automotive chassis during the detailed design stage. The first process iteratively applies forces to the model and records displacements, while the second process gradually applies vertical displacements in place of force to determine the torsional stiffness threshold. Each method is explained and supported with a case study to provide a basis of comparison of the results.

scholarly journals Skateboarding as a tool for reading the city

2019 ◽  
Author(s):  
Polina Yu. Krutskikh
Keyword(s):  
Urban Youth ◽  
Analytical Approach ◽  
Youth Sports ◽  
Urban Infrastructure ◽  
Complex Nature ◽  
Academic Context ◽  
The Common ◽  
The City

Modern urban youth sports cultures are notable for their diverse and complex nature. The question arises as to what analytical approach should be used to study their multifaceted character. Using the St Petersburg skateboard scene as an example, the article shows the advantages in applying the concept of the post-sport cultures to understand how the common functions of urban infrastructure are redefined, what trends exist on the scene, how they shape the meanings attributed to them by the scene participants, and how those signs are read.  The study also employs the solidarity approach to describe the interactions between the scene participants through the ideas and ideological controversies shared by them. The focus of the paper is how to apply solidarity approach to study the nature of urban post-sport cultures based on St Petersburg skateboard scene case study. Given the lack of Russian publications on the topic, the study is also aimed at inscribing the Russian skateboarding experience into the Western academic context.

Availability of Compliance Status in the Documentary Credit Opening Contract: A Study on the Jordanian Legislations

2021 ◽  
Vol 12 (2) ◽  
pp. 41
Author(s):  
Abdulwahab Abdullah Al Maamari ◽  
Abdallah Hameed Al Ghuwairi
Keyword(s):  
Foreign Trade ◽  
Analytical Approach ◽  
Legal Protection ◽  
Strong Relationship ◽  
The Other ◽  
Letter Of Credit ◽  
Banking Operations

The letter of credit (L/C) contract is one of a range of banking operations through which banks can finance foreign trade. The contract provides security and stability to the trade because of the trust and credit it gives, since the buyer may be in one country and the seller in another, so as to assure each other that the other party fulfills its obligation. However, is this contract can be considered as a compliance contract so the relations between parties is a submissive weak-strong relationship? This necessarily entails examining the availability of legal protection to prevent the abuse of a strong party. Hence, this paper aims to examine the availability of compliance status in the documentary credit opening contract and focuses on the Jordanian legislations as a case study. The comparative analytical approach is executed in this study. The findings reveal that the L/C contract is influenced by the concept of compliance, however the L/C contract can be adjusted by the client, in accordance with the rules and provisions of this credit.   Received: 31 January 2021 / Accepted: 27 February 2021 / Published: 7 March 2021

Mechanistic understanding of the sensing process by analyzing response curves of TiO2 based humidity sensors

2021 ◽  
Vol 12 (4) ◽  
pp. 045010
Author(s):  
Balaji Rakesh ◽  
Nipun Sharma ◽  
Rupali Nagar ◽  
Vipul Dhongade ◽  
Krishna Daware ◽  
...  
Keyword(s):  
Food Packaging ◽  
Sol Gel ◽  
Fast Response ◽  
Response Curves ◽  
Initial State ◽  
Sensing Material ◽  
Adsorption Processes ◽  
Low Humidity ◽  
Mechanistic Understanding

Abstract Sensors function by interacting with an appropriate stimulus, undergo a change in property, which is then diagnosed by making some measurements. For any sensor, the type of interaction between analyte and sensor surface determines its overall performance. This article explores the philosophy in which primary measurements like response curves can hold information on the “type” of interaction occurring between analyte and sensing material. As case study, titanium oxide (TiO2) pellet sensors fabricated by sol-gel growth of TiO2 nanoparticles (as-grown and annealed) are investigated for humidity sensing at room temperature. The sensors display a very fast response in the 0%–30% relative humidity (%RH) range and return to their initial state without applying any external heat treatment. The response curves are analysed in view of adsorption processes guided by Langmuir isotherms. Correlation between sensor microstructure, adsorption processes and response curve is used to build the mechanistic understanding of the sensing process. The results bring out a unique correlation between sensor microstructure, interaction of analyte with sensing material and profile of response curves. Further, the synthesised sensors exhibit a linear response in the 0%–30% RH range making them suitable for low humidity environments like food packaging industry.

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