scholarly journals DETERMINATION OF THE WAVE ATTACK ANTICIPATED UPON A STRUCTURE FROM LABORATORY AND FIELD OBSERVATIONS

2011 ◽  
Vol 1 (7) ◽  
pp. 37
Author(s):  
W.A. Venis
Keyword(s):  
Comparative Study ◽  
Model Tests ◽  
Water Levels ◽  
Field Observations ◽  
Wave Impact ◽  
Spring System ◽  
Mass Spring ◽  
The Comparative Study ◽  
The Impact

Model tests have been carried out to obtain an insight into the magnitude of the wave-pressures in various situations. These tests showed, that sharp high pressure peaks occur in addition to the pressures caused by the reflecting of the waves, which pressures are quasi-static. As the structure can be compared with a multiple mass-spring system these pressure-peaks may cause the whole construction to vibrate. Wave-attack therefore can be expressed in terms of impact. Moreover, calculations revealed that the impact pressures were critical factors in determining the strength of the structure. So many model tests were carried out to determine the design and location of the sluices. These tests involved numerous water-levels discharges and waves. Regarding the pressure-peaks a comparative study was made in the model, which led to the structure being designed in such a way that the occurrence of critical impacts was reduced to an acceptable minimum. As it was impossible to avoid the occurrence of impact pressures entirely it remained necessary to determine a basic load for the structure that takes care of the impact pressures. As it has not yet appeared possible physically to determine a theoretical maximum for the impact pressures, it has to be borne in mind that there is a probability that each pressure measured will be exceeded. So this paper describes, how the cumulative frequency curve of the impacts for the case mentioned in 1.1 sub a, which served as a basis for determining the basic load was arrived at by a certain combination of laboratory and field observations. The data used for this purpose were a. Results of wave-impact measurements on a model of the sluices. This model, built in accordance with the results of the comparative study, was situated in the wind-flume of the "de Voorst" hydraulic laboratory. b. Wave height measurements in the Haringvliet during 1957 and 1958. c. Wind-speed measurements on board the lightship Qoeree, likewise during 1957 and 1958. d. Tidal registrations at Hellevoetsluis from 1920 to 1960. e. Wind-force data from the Hook of Holland, likewise from 1920 to 1960.

Wave Impact Loads on the Bottom of Flat Decks

2021 ◽  
Author(s):  
Daniel de Oliveira Costa ◽  
Julia Araújo Perim ◽  
Bruno Guedes Camargo ◽  
Joel Sena Sales Junior ◽  
Antonio Carlos Fernandes ◽  
...  
Keyword(s):  
Scale Effects ◽  
Offshore Structures ◽  
Model Tests ◽  
Analytical Models ◽  
Navier Stokes ◽  
Impact Loads ◽  
Wave Impact ◽  
Wave Channel ◽  
Waves And Currents ◽  
The Impact

Abstract Slamming events due to wave impact on the underside of decks might lead to severe and potentially harmful local and/or global loads in offshore structures. The strong nonlinearities during the impact require a robust method for accessing the loads and hinder the use of analytical models. The use of computation fluid dynamics (CFD) is an interesting alternative to estimate the impact loads, but validation through experimental data is still essential. The present work focuses on a flat-bottomed model fixed over the mean free surface level submitted to regular incoming waves. The proposal is to reproduce previous studies through CFD and model tests in a different reduced scale to provide extra validation and to identify possible non-potential scale effects such as air compressibility. Numerical simulations are performed in both experiments’ scales. The numerical analysis is performed with a marine dedicated flow solver, FINE™/Marine from NUMECA, which features an unsteady Reynolds-averaged Navier-Stokes (URANS) solver and a finite volume method to build spatial discretization. The multiphase flow is represented through the Volume of Fluid (VOF) method for incompressible and nonmiscible fluids. The new model tests were performed at the wave channel of the Laboratory of Waves and Currents (LOC/COPPE – UFRJ), at the Federal University of Rio de Janeiro.

Federalism

2009 ◽  
Author(s):  
Pablo Beramendi
Keyword(s):  
Comparative Study ◽  
Rational Choice ◽  
Comparative Politics ◽  
Basic Premise ◽  
Methodological Considerations ◽  
The Comparative Study ◽  
The Impact

This article provides a partial but necessary review of the dominating themes, evolution, and pending tasks that await the comparative politics of federalism. The basic premise of this article is taken from rational choice institution-alism. The article fist delimits federalism as an institution, before it pays attention to the impact of federalism on democracy and the workings of the economy. An analysis of federalism as an endogenous institution is provided. The article also mentions a number of methodological considerations on the comparative study of the origins and consequences of federalism. It ends with a discussion of the various challenges that lie ahead of the field.

Numerical Study of Phase Change Influence on Wave Impact Loads in LNG Tanks on Floating Structures

2018 ◽  
Author(s):  
Matthieu Ancellin ◽  
Laurent Brosset ◽  
Jean-Michel Ghidaglia
Keyword(s):  
Natural Gas ◽  
Phase Change ◽  
Numerical Study ◽  
Model Tests ◽  
Impact Loads ◽  
Wave Impact ◽  
Floating Structures ◽  
Physical Phenomena ◽  
The Impact ◽  
Phase Phase

Understanding the physics of sloshing wave impacts is necessary for the improvement of sloshing assessment methodology based on sloshing model tests, for LNG membrane tanks on floating structures. The phase change between natural gas and liquefied natural gas is one of the physical phenomena involved during a LNG wave impact but is not taken into account during sloshing model tests. In this paper, some recent numerical and analytical works on the influence of phase change are summarized and discussed. For the impact of an ideally shaped wave, phase change influences two different steps of the impact in different ways: during the gas escape phase, phase change leads to a higher impact velocity; for entrapped gas pockets, phase change causes a reduction of the pressure in the gas pocket. However, this influence is quantitatively small. The generalization to more realistic wave shapes (including e.g. liquid aeration) should be the focus of future works.

scholarly journals Neural Network Control of a Robot Interacting With an Uncertain Hunt-Crossley Viscoelastic Environment

2008 ◽  
Author(s):  
S. Bhasin ◽  
K. Dupree ◽  
P. M. Patre ◽  
W. E. Dixon
Keyword(s):  
Neural Network ◽  
Network Control ◽  
Contact Dynamics ◽  
Neural Network Control ◽  
Contact Conditions ◽  
Real Behavior ◽  
Spring System ◽  
Mass Spring ◽  
The Impact ◽  
Viscoelastic Contact

The objective in this paper is to control a robot as it transitions from a non-contact to a contact state with an unactuated viscoelastic mass-spring system such that the mass-spring is regulated to a desired final position. A nonlinear Hunt-Crossley model, which is physically consistent with the real behavior of the system at contact, is used to represent the viscoelastic contact dynamics. A Neural Network feedforward term is used in the controller to estimate the environment uncertainties, which are not linear-in-parameters. The NN Lyapunov based controller is shown to guarantee uniformly ultimately bounded regulation of the system despite parametric and nonparametric uncertainties in the robot and the viscoelastic environment respectively. The proposed controller only depends on the position and velocity terms, and hence, obviates the need for measuring the impact force and acceleration. Further, the controller is continuous, and can be used for both non-contact and contact conditions.

Small respiratory passages dysfunction in bronchial asthma

2020 ◽  
Vol 29 (6) ◽  
pp. 725-733
Author(s):  
O. Yu. Kytikova ◽  
M. V. Antonyuk ◽  
B. I. Gel'tser ◽  
E. E. Mineeva ◽  
T. A. Gvozdenko
Keyword(s):  
Comparative Study ◽  
Disease Control ◽  
Bronchial Asthma ◽  
Scientific Knowledge ◽  
Clinical Course ◽  
Pathological Process ◽  
Modern Methods ◽  
The Comparative Study ◽  
The Impact ◽  
Timely Treatment

The small respiratory passages dysfunction (SRPD) is found in the vast majority of patients with bronchial asthma (BA). The SRPD is currently recognized as the important pathogenetic feature of BA. The purpose of this review is to analyze the current scientific knowledge about the poorly studied aspects of the small respiratory passages (SRR) participation in the development of pathological process in BA, as well as the impact of small bronchial dysfunction on the clinical course, the exacerbation frequency and the disease control. The importance of SRPD diagnostics in BA patients for optimal and timely treatment is discussed. The modern methods of RPD pathology diagnostics are described; their informative use in the comparative study aspect is considered.

scholarly journals Assessment of Salivary Catalase, α-Amylase, and Cotinine Levels in Chronic Smokers: A Comparative Study

2018 ◽  
Vol 19 (3) ◽  
pp. 253-256 ◽  
Author(s):  
Satvinder Singh ◽  
Mamta Sharma ◽  
Nitika Rohilla ◽  
Varun Salgotra ◽  
Varun Kumar ◽  
...  
Keyword(s):  
Comparative Study ◽  
Harmful Effect ◽  
Study Groups ◽  
Potential Effect ◽  
Enzyme Linked Immunosorbent Assay ◽  
Salivary Cotinine ◽  
Elisa Technique ◽  
The Common ◽  
The Impact

ABSTRACT Introduction One of the common practices observed in many parts of the world is smoking, of which tobacco forms an important constituent which is burned and inhaled. Smoking is known to have potential effect on body’s immune system, antioxidants level, and salivary cotinine levels. Hence, we planned the present study to evaluate the impact of cigarette smoke on salivary antioxidant levels and cotinine levels in smokers and nonsmokers. Materials and methods The present study included assessment of salivary parameters of smokers and nonsmokers. A total of 400 subjects were analyzed, of which 200 were active smokers and 200 were nonsmokers. Unstimulated salivary samples were taken and assessment of α-amylase levels was done using biochemical kit and spectrophotometer. Assessment of salivary catalase (CAT) activity was done using Luck method. For the determination of cotinine levels, Bioassay Technology Laboratory kit was used using enzyme-linked immunosorbent assay (ELISA) technique. After the assessment of levels of all the salivary parameters, all the data were recorded, compiled, and analyzed. Results α-Amylase in smokers and nonsmokers group was found to be 206.25 and 169.85 U/mL respectively. Nonsignificant results were obtained while comparing the salivary α-amylase levels among the two study groups. Nonsignificant results were obtained while comparing the salivary CAT levels among the smokers and nonsmokers group. We observed statistically significant results while comparing mean cotinine levels among smokers group and nonsmokers group. Conclusion Alteration in cotinine levels occurs in smokers in comparison to nonsmokers. Clinical significance Smoking can cause harmful effect on the oral mucous membrane by altering salivary defense components. How to cite this article Singh S, Sharma M, Rohilla N, Salgotra V, Kumar V, Sharma RK. Assessment of Salivary Catalase, α-Amylase, and Cotinine Levels in Chronic Smokers: A Comparative Study. J Contemp Dent Pract 2018;19(3):253-256.

Evaluation of biodegradation kinetics of organic wastewater in a laboratory river model

1994 ◽  
Vol 30 (10) ◽  
pp. 229-235 ◽  
Author(s):  
J. Zagorc-Koncan ◽  
M. Dular
Keyword(s):  
Comparative Study ◽  
Surface Waters ◽  
Organic Pollution ◽  
Wastewater Effluent ◽  
Biodegradation Kinetics ◽  
River Waters ◽  
Point Of Entry ◽  
The Impact ◽  
Kinetics Of

A laboratory river model for the study of biodegradation kinetics of organic pollution in surface waters is presented. It enables an engineering - technological prediction of the impact of wastewater biodegradation on DO and TOC profile in a river downstream from the point of entry of wastewater effluent thus providing rapidly and inexpensively significant design information to an environmental scientist or engineer. The method was applied to the determination of degradation of pharmaceutical wastewaters. Biodegradation during adaptation and a comparative study on organic constituents, biodegradation rates in polluted and unpolluted river waters were simulated.

Time domain force identification based on adaptive ℓq regularization

2018 ◽  
Vol 24 (23) ◽  
pp. 5610-5626 ◽  
Author(s):  
Qiaofeng Li ◽  
Qiuhai Lu
Keyword(s):  
Prior Knowledge ◽  
Time Domain ◽  
Identification Problem ◽  
Engineering Practice ◽  
Force Identification ◽  
Continuous Type ◽  
Force Profile ◽  
Spring System ◽  
Mass Spring

Traditional time domain force identification methods require prior knowledge about the force profile to apply the appropriate regularization term. Generally speaking, ℓ1 and ℓ2 regularization are applied for sparse-type and continuous-type forces respectively. However, prior knowledge about the force type may be unavailable in engineering practice. It is then necessary to incorporate the determination of q (as in ℓq regularization) into the identification process. In this paper, we propose two methods to address the problem: the joint and marginal posterior modes of the force history. The identification problem is formulated within the Bayesian framework. The force history, precision parameters, and q are all treated as unknown random parameters, and estimated based on vibration measurements only. The proposed methods are numerically validated on a mass–spring system, an engineering-scale support structure and experimentally validated on a cantilever beam. It is shown that the proposed methods by considering the data-driven determination of q could adapt to the force profile and consistently provide satisfactory results.

Determination of Spring Constant for Simulating Deformable Object under Compression

2009 ◽  
Vol 417-418 ◽  
pp. 369-372
Author(s):  
Koeng Wook Ko ◽  
Hyun Soo Kim ◽  
Sung In Bae ◽  
Eui Seok Kim ◽  
Yuan Shin Lee
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Spring Constant ◽  
Deformable Objects ◽  
Spring Model ◽  
Mass Spring Model ◽  
Spring System ◽  
Mass Spring ◽  
Spring Constants

It is not easy to simulate realistic mechanical behaviors of elastically deformable objects with most existing mass-spring systems for their lack of simple and clear methods to determine spring constants considering material properties (e.g. Young's modulus, Poisson’s ratio). To overcome this obstacle, we suggest an alternative method to determine spring constants for mechanical simulation of deformable objects under compression. Using the expression derived from proposed method, it is possible to determine one and the same spring constant for a mass-spring model depending on Young's modulus, geometric dimensions and mesh resolutions of the 3-D model. Determination of one and the same spring constant for a mass-spring model in this way leads to simple implementation of the mass-spring system. To validate proposed methodology, static deformations (e.g. compressions and indentations) simulated with mass-spring models and FEM reference models are compared.

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