scholarly journals IMPACT WAVE FORCES ON VERTICAL AND HORIZONTAL PLATE

1978 ◽  
Vol 1 (16) ◽  
pp. 141
Author(s):  
S.R. Massel ◽  
M. Oleszkiewicz ◽  
W. Trapp
Keyword(s):  
Water Waves ◽  
Difficult Problem ◽  
Wave Forces ◽  
Horizontal Plate ◽  
Hydrodynamic Impact ◽  
Impact Forces ◽  
Wave Parameters ◽  
The Subject ◽  
The Impact ◽  
Impact Problem

The hydrodynamic impact problem is a very difficult problem because the physics of what actually happens during the instant of impact are not understood. Despite of fact that a large number of references exist on the subject, many questions are left unanswered. The object of this research is to investigate the problems of hydrodynamic impact associated with the water waves impacting on the vertical and horizontal plates..Of particular interest are the impact forces, their relation to the incident wave parameters and scale effect problems.

Hydrodynamic Impact Analysis of a Cylinder

1987 ◽  
Vol 109 (3) ◽  
pp. 237-243 ◽  
Author(s):  
R. Cointe ◽  
J.-L. Armand
Keyword(s):  
Impact Analysis ◽  
Impact Force ◽  
Horizontal Cylinder ◽  
Inviscid Fluid ◽  
Hydrodynamic Impact ◽  
Impact Forces ◽  
Corrective Term ◽  
Simplifying Assumptions ◽  
New Formula ◽  
The Impact

The problem of the vertical entry of a rigid horizontal cylinder into an incompressible inviscid fluid initially at rest is addressed. The contributions of previous researchers are presented and discussed in the light of various assumptions introduced and the validity of the results obtained. Based on this review, realistic simplifying assumptions are introduced and the problem formulated. The method of matched asymptotic expansions is used to solve the resulting boundary-value problem. A new formula for the impact force is obtained, which differs from the classical von Ka´rma´n’s formula by a corrective term. The results obtained are compared with those of experimental observations and numerical calculations. The method may be extended to different geometries and nonvertical velocities to provide an estimate of the impact forces on the partially emerged pontoons of damaged semi-submersibles.

Experimental Validation of Inverse Techniques for the Remote Identification of Impact Forces in Gap-Supported Systems Subjected to Local and Flow Turbulence Excitations

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Xavier Delaune ◽  
Philippe Piteau ◽  
Vincent Debut ◽  
Jose Antunes
Keyword(s):  
Real Life ◽  
Relevant Information ◽  
Contact Forces ◽  
Modal Identification ◽  
Practical Significance ◽  
Significant Feature ◽  
Impact Forces ◽  
The Subject ◽  
Identification Techniques ◽  
The Impact

Predictive computations of the nonlinear dynamical responses of gap-supported tubes subjected to flow excitation have been the subject of active research. Nevertheless, experimental results are still necessary for validation of the theoretical predictions as well as for asserting the integrity of field components. Because carefully instrumented test tubes and tube-supports are seldom possible, due to space limitations and to the severe environment conditions, there is a need for robust techniques capable of extracting relevant information from the actual vibratory response data. Although at the present time such analysis is overambitious, as far as the multisupported tube bundles of real-life components are concerned, the same instrumentation difficulties frequently apply in the case of laboratory test rigs. Therefore, the subject of this paper is of practical significance even in the more modest realm of laboratory experiments. The knowledge of the dynamical contact/impact (vibro-impact) forces is of paramount significance, and also the tube/support gaps. Following our previous studies in this area using wave-propagation techniques (De Araújo et al., 1998; Antunes et al., 1998; Paulino et al., 1999), we recently applied modal methods for extracting such information. Based on numerically simulated time-domain vibro-impact responses, the dynamical support forces, as well as the vibratory responses at the support locations, were identified from one or several vibratory responses at remote locations, from which the support gaps could also be inferred (Delaune et al., 2010). Also recently, for the related problem of friction force identification on bowed strings, preliminary experiments have shown the feasibility of these identification techniques (Debut et al., 2010). In the present paper, the modal identification techniques developed by Delaune et al. (2010) and Debut et al. (2010) are tested using an experimental rig built at Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA/Saclay), consisting of a randomly excited clamped-free beam which impacts on an intermediate gap-support. Identification of the impact force, as well as of the beam motion at the gap-support, is achieved based on remote measurements of the beam response provided by two accelerometers. A significant feature of the experimental identifications presented in this paper is that, beyond the results obtained under a point-force shaker excitation, we test here an original technique to identify the gap-supported reactions in flow-excited systems, which was recently introduced by Delaune et al. (2010). As for most inverse problems, the identification results may prove sensitive to both noise and modeling errors. Therefore, regularization techniques discussed by Delaune et al. (2010) are used to mitigate the effects of unmeasured noise perturbations. Overall, the experimentally identified results compare reasonably well with the measured contact forces and motions at the gap-supports. Actually, even if our identifications are not immaculate at the present time, they remain nevertheless quite usable.

scholarly journals NUMERICAL MODELLING OF SOLITARY AND FOCUSED WAVE FORCES ON COASTAL-BRIDGE DECK

2018 ◽  
pp. 12 ◽  
Author(s):  
Rameeza Moideen ◽  
Manasa Ranjan Behera ◽  
Arun Kamath ◽  
Hans Bihs
Keyword(s):  
Water Waves ◽  
Bridge Deck ◽  
Experimental Studies ◽  
Wave Forces ◽  
Extreme Waves ◽  
Shallow Water Waves ◽  
Wave Impact ◽  
Coastal Bridges ◽  
Focused Wave ◽  
The Impact

In the recent past, coastal bridges have been subjected to critical damage due to extreme wave attacks during natural calamities like storm surge and tsunami. Various numerical and experimental studies have suggested different empirical equations for wave impact on deck. However, they do not account the velocities of the wave type properly, which requires a detailed investigation to study the impact of extreme waves on decks. Solitary wave assumption is more suitable for shallow water waves, while the focused wave has been used widely to represent extreme waves. The present study aims to investigate the focused wave impact on coastal bridge deck using REEF3D (Bihs et al., 2016).

Experimental Validation of Inverse Techniques for the Remote Identification of Impact Forces in Gap-Supported Systems Subjected to Local and Flow Turbulence Excitations

2010 ◽  
Author(s):  
Xavier Delaune ◽  
Philippe Piteau ◽  
Vincent Debut ◽  
Jose Antunes
Keyword(s):  
Real Life ◽  
Relevant Information ◽  
Contact Forces ◽  
Modal Identification ◽  
Practical Significance ◽  
Significant Feature ◽  
Impact Forces ◽  
The Subject ◽  
Identification Techniques ◽  
The Impact

Predictive computations of the nonlinear dynamical responses of gap-supported tubes subjected to flow excitation have been the subject of active research. Nevertheless, experimental results are still necessary, for validation of the theoretical predictions as well as for asserting the integrity of field components. Because carefully instrumented test tubes and tube-supports are seldom possible, due to space limitations and to the severe environment conditions, there is a need for robust techniques capable of extracting relevant information from the actual vibratory response data. Although at the present time such analysis is over-ambitious, as far as the multi-supported tube bundles of real-life components are concerned, the same instrumentation difficulties frequently apply in the case of laboratory test rigs. Therefore, the subject of this paper is of practical significance even in the more modest realm of laboratory experiments. The knowledge of the dynamical contact/impact (vibro-impact) forces is of paramount significance, as also the tube/support gaps. Following our previous studies in this area using wave-propagation techniques [1–3], we recently applied modal methods for extracting such information. Based on numerically simulated time-domain vibro-impact responses, the dynamical support forces, as well as the vibratory responses at the support locations, were identified from one or several vibratory responses at remote locations, from which the support gaps could also be inferred [4]. Also recently, for the related problem of friction force identification on bowed strings, preliminary experiments have shown the feasibility of these identification techniques [5]. In the present paper, the modal identification techniques developed in [4,5] are tested using an experimental rig built at CEA/Saclay, consisting on a randomly excited clamped-free beam which impacts on an intermediate gap-support. Identification of the impact force, as well as of the beam motion at the gap-support, are achieved based on remote measurements of the beam response provided by two accelerometers. A significant feature of the experimental identifications presented in this paper is that, beyond the results obtained under a point-force shaker excitation, we test here an original technique to identify the gap-supported reactions in flow-excited systems, which was recently introduced in [4]. As for most inverse problems, the identification results may prove sensitive to both noise and modeling errors. Therefore, regularization techniques discussed in [4] are used to mitigate the effects of unmeasured noise perturbations. Overall, the experimentally identified results compare reasonably well with the measured contact forces and motions at the gap-supports. Actually, even if our identifications are not immaculate at the present time, they remain nevertheless quite usable.

Preliminary Evaluation of the Flooding Effects on an Existing PWR

2013 ◽  
Author(s):  
Vincenzo Baudanza ◽  
Rosa Lo Frano ◽  
Giuseppe Forasassi
Keyword(s):  
Water Waves ◽  
Safety Margin ◽  
Breaking Waves ◽  
Preliminary Evaluation ◽  
Structural Effects ◽  
Fukushima Accident ◽  
Concrete Material ◽  
Impact Forces ◽  
The Impact ◽  
Severe Flooding

The aim of the study is the evaluation of the structural effects induced by a severe flooding or tsunami (which is one of the external events to be considered for the safety margin reassessment purpose according to the International requirements, after the Fukushima accident) in an outer containment walls of a typical PWR. The hydrodynamic forces exerted by the breaking waves, characterizing the inundation phase of tsunami/flooding phenomenon, are calculated in agreement with ASME rules. Therefore to evaluate the consequences and damages, if any, induced by the breaking water waves which have arisen on an existing PWR containment building, non linear analyses (by using an adequate FEM code) were performed simulating the impact forces of the water waves in terms of pressure. Moreover a FSI analysis was carried out in order to verify the adequacy (and consistency) of the methodology adopted in the evaluation of the pressure forces mentioned above. To analyze the performances of the containment building suitable reinforced concrete material properties and damage phenomena features were considered. The results obtained highlighted that the tsunami effects are strongly dependent on the wave height, flow velocity, hydrodynamic phenomena and on the geometry and material behaviour of the analyzed structures. Finally they showed that the containment building considered seemed capable to withstand the flooding/tsunami effects without loss of the integrity of PWR containment structure.

Remote Identification of Impact Forces on Loosely Supported Tubes: Analysis of Multi-Supported Systems

1999 ◽  
Vol 121 (1) ◽  
pp. 61-70 ◽  
Author(s):  
M. Paulino ◽  
J. Antunes ◽  
P. Izquierdo
Keyword(s):  
Traveling Waves ◽  
Heat Exchangers ◽  
Difficult Problem ◽  
Force Identification ◽  
Dissipative Effects ◽  
Impact Forces ◽  
Random Forces ◽  
Direct Measurements ◽  
Remote Identification ◽  
The Impact

Impact forces are useful information in field monitoring of many industrial components, such as heat exchangers, condensers, etc. In two previous papers we presented techniques—based on vibratory measurements remote from the actual impact locations—for the experimental identification of isolated impacts (Arau´jo et al., 1996) and complex rattling forces (Antunes et al., 1997). In both papers a single gap support was assumed. Those results concern systems which are simpler than the actual multi-supported tube bundles found in heat exchangers. Impact force identification is a difficult problem for such systems, because 1) when sensed by the remote motion transducers, the traveling waves generated at several impact supports are mixed, and there is no obvious way to isolate the contribution of each support; 2) multi-supported tubes may be quite long, with significant dissipative effects (by interacting flows or by frictional phenomena at the clearance supports), leading to some loss of the information carried by the traveling waves; 3) in multi-supported systems, some of the supports are often in permanent contact, leading to nonimpulsive forces which are difficult to identify. In this paper, we move closer towards force identification under realistic conditions. Only the first problem of wave isolation is addressed, assuming that damping effects are small and also that all clearance supports are impacting. An iterative multiple-identification method is introduced, which operates in an alternate fashion between the time and frequency domains. This technique proved to be effective in isolating the impact forces generated at each gap support. Experiments were performed on a long beam with three clearance supports, excited by random forces. Beam motions were planar, with complex rattling at the supports. Experimental results are quite satisfactory, as the identified impact forces compare favorably with the direct measurements.

Managing Service Quality, Food Quality, Price Fairness and Customer Retention: A Holistic Perspective

2020 ◽  
Vol 2 (1) ◽  
pp. 1-5
Author(s):  
Ammar Ahmed ◽  
Rafat Naseer ◽  
Muhammad Asadullah ◽  
Hadia Khan
Keyword(s):  
Service Quality ◽  
Food Quality ◽  
Service Sector ◽  
Customer Retention ◽  
Price Fairness ◽  
Policy Makers ◽  
Restaurant Management ◽  
The Subject ◽  
Research Propositions ◽  
The Impact

In this competitive environment, organizations strive to satisfy their customer by providing best quality service at affordable and fair prices with a view to enhance their revenues. To achieve the objective of revenue maximization, organizations strive to identify the factors that help them in retaining their customers. Drawing from the signalling theory of marketing, the current study proposes a novel conceptual model representing the impact of service quality with food quality and price fairness on customer retention in restaurant sector of Pakistan. The paper underlines an important arena of knowledge for academicians as well as organizational scientists on the subject. On the basis of literature available on the variables understudy, the present study forwards eight research propositions worthy of urgent scholarly attention. The conceptualized model of the present article can also be viewed significant in unleashing further avenues for the restaurant management entities, policy makers and future researchers in the domain of managing in the service sector businesses.

Solow economy model

2019 ◽  
pp. 150-157
Author(s):  
Oleksandr Synenko ◽  
Kateryna Yarema ◽  
Yuliia Bezsmertna
Keyword(s):  
Economic Growth ◽  
Regression Analysis ◽  
Solow Model ◽  
Economy Model ◽  
Accelerated Depreciation ◽  
Basic Parameters ◽  
The Subject ◽  
Investment Process ◽  
The Impact ◽  
Model Algorithm

The subject of the research is the approach to the possibility of using the Solow model to perform the regression analysis on the example of the Ukrainian economy model. The purpose of writing this article is to investigate the notion of regres- sion analysis, Solow’s economy model, algorithm for performing regression analy- sis on the example of Ukraine’s economy model. This model can be adapted for the economy of enterprises. Methodology. The research methodology is system-struc- tural and comparative analyzes (to study the structure of GDP); monograph (when studying methods of regression analysis on the example of the Ukrainian economy); economic analysis (when assessing the impact of factors on Ukraine’s GDP). The scientific novelty consists the features of the use of the Solow model on the ex- ample of Ukrainian economy are determined. An algorithm for calculating the basic parameters of a model using the Excel application package is disclosed. The main recommendations on the development of the national economy and economic growth through the use of macroeconomic instruments are given. Conclusions. The use of the Solow model enables forecasting and analysis. The results obtained re- vealed the problem of low resource return of capital as a resource, along with the means of macroeconomic regulation of the investment process, using which can improve the situation. A special place in these funds belongs to the accelerated depreciation and interest rate policies.

Assessment of small businesses activities in Ukraine

2019 ◽  
pp. 40-47
Author(s):  
Igor Ponomarenko ◽  
Kateryna Volovnenko
Keyword(s):  
Comparative Analysis ◽  
Statistical Analysis ◽  
Small Business ◽  
Small Businesses ◽  
Government Agencies ◽  
Small Enterprises ◽  
The Subject ◽  
Business Entities ◽  
The Impact ◽  
Micro Enterprises

The subject of the research is a set of approaches to the statistical analysis ofthe activities of small business entities in Ukraine, including micro-enterprises. The purpose of writing this article is to study of the features of functioningof small business entities in Ukraine. Methodology. The research methodology isto use a system-structural and comparative analysis (to study the change in thenumber of small enterprises by major components); monographic (when studyingmethods of statistical analysis of small businesses); economic analysis (when assessing the impact of small business entities on socio-economic phenomena andprocesses in Ukraine). The scientific novelty consists to determine the features ofthe functioning of small businesses in Ukraine in modern conditions. The influenceof the activities of the main socio-economic and political indicators on the activities of small enterprises in recent periods of time has been identified. It has beenestablished that there is flexibility in the development of strategies by small businesses in conditions of significant competition, which makes it possible to quicklyrespond to changing situations in specific markets. Conclusions. The use of acomprehensive statistical analysis of small businesses functioning in Ukraine willallow government agencies to develop a set of measures to optimize the activitiesof these enterprises, which ultimately will positively affect the strengthening oftheir competitiveness and will contribute to the growth of the national economicsystem.

The Impact of Quantitative Easing on Emerging Markets – Literature Review

e-Finanse ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 67-76
Author(s):  
Piotr Bartkiewicz
Keyword(s):  
Emerging Markets ◽  
Large Scale ◽  
Empirical Literature ◽  
Quantitative Easing ◽  
Methodological Choices ◽  
The Subject ◽  
Methodological Approaches ◽  
The Impact ◽  
Sufficient Precision

AbstractThe article presents the results of the review of the empirical literature regarding the impact of quantitative easing (QE) on emerging markets (EMs). The subject is of interest to policymakers and researchers due to the increasingly larger role of EMs in the world economy and the large-scale capital flows occurring after 2009. The review is conducted in a systematic manner and takes into consideration different methodological choices, samples and measurement issues. The paper puts the summarized results in the context of transmission channels identified in the literature. There are few distinct methodological approaches present in the literature. While there is a consensus regarding the direction of the impact of QE on EMs, its size and durability have not yet been assessed with sufficient precision. In addition, there are clear gaps in the empirical findings, not least related to relative underrepresentation of the CEE region (in particular, Poland).

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