scholarly journals THE EFFECT OF WAVES ON THE PROFILE OF A NATURAL BEACH

1968 ◽  
Vol 1 (11) ◽  
pp. 23
Author(s):  
Warren C. Thompson ◽  
John C. Harlett
Keyword(s):  
Field Data ◽  
Initial Conditions ◽  
Empirical Relationship ◽  
Wave Power ◽  
Wave Steepness ◽  
Beach Profile ◽  
Wave Parameters ◽  
Equilibrium Profiles ◽  
The Relationship ◽  
The Waves

A 60-day field study was conducted on a selected natural beach in which the beach profile was measured daily and the waves incident upon the profile were recorded continuously. Beach and wave parameters derived from the field data were empirically combined to yield: (a) quantitative relationships between the change in the profile and the-average deepwater wave steepness and wave power over a lunar day (24.8 hours) given the profile at the beginning of the period, (b) equilibrium profiles for different values of wave steepness, (c) an empirical relationship between wave steepness and wave power which agrees well with theory, and (d) rates at which the beach profile approached equilibrium for given initial conditions of non-equilibrium. Using the relationship developed between beach change and wave steepness, hindcasts were made of the day-to-day sand elevation at a selected location near the middle of the profile and were found to agree fairly well with the observed sand level.

scholarly journals INFLUENCE OF WAVE TRANSFORMATION PROCESSES ON EVOLUTION OF UNDERWATER BEACH PROFILE

2018 ◽  
pp. 65 ◽  
Author(s):  
Yana Saprykina ◽  
Olga Kuznetsova
Keyword(s):  
Experimental Data ◽  
Wave Breaking ◽  
Qualitative Assessment ◽  
Wave Transformation ◽  
Wave Steepness ◽  
Beach Profile ◽  
Physical Processes ◽  
Peak Period ◽  
Wave Parameters ◽  
Transformation Processes

On the base of field experimental data were confirmed that the main wave parameters for cross-shore sediment transport are the significant wave height, spectral peak period and wave steepness. Waves with narrowband spectrum more effect on changes of underwater profile. For a qualitative assessment of erosion/accumulation the Dean parameter, the Ursell and Iribarren numbers can be used. However the physical processes of wave transformation play an important role. The most significant are nonlinear wave transformation and wave breaking, especially the type of wave breaking.

scholarly journals THE RELATIONSHIP BETWEEN WAVE ACTION AND BEACH PROFILE CHARACTERISTICS

2011 ◽  
Vol 1 (7) ◽  
pp. 14 ◽  
Author(s):  
P.H. Kemp
Keyword(s):  
Rational Design ◽  
Break Point ◽  
Coarse Sand ◽  
Beach Erosion ◽  
Beach Profile ◽  
Model Study ◽  
Materials Used ◽  
Profile Characteristics ◽  
The Relationship ◽  
The Waves

The rational design of coast protection works requires a knowledge of the behaviour of the beach under natural conditions. The understanding of the relationship between the waves acting on the beach and the characteristics of the beach profile produced, is thus a necessary preliminary to the analysis of the causes of beach erosion and the evaluation of the effect of projected remedial measures. The present paper describes the results of a series of preliminary hydraulic model experiments carried out by the author prior to a model study of the behaviour of groynes in stabilising beaches. Most of the beach materials used represented coarse sand or shingle in nature. The results demonstrate the fundamental importance of the "phase difference" in terms of wave period between the break-point and the limit of uprush, in relation to flow conditions, cusp formation, and the change from "step" to "bar" type profiles. Within the limits of the experiments an expression connecting the breaker height, beach profile length, and grain diameter is developed, and its implications examined in relation to beach slope, and to the previous "wave steepness" criterion for the change from step to bar type profiles. Observations are included on the rate of recession of a shoreline due to the onset of more severe wave conditions.

scholarly journals Velocity of E-region HF echoes under strongly-driven electrojet conditions

2012 ◽  
Vol 30 (1) ◽  
pp. 235-250 ◽  
Author(s):  
J. D. Gorin ◽  
A. V. Koustov ◽  
R. A. Makarevich ◽  
J.-P. St. -Maurice ◽  
S. Nozawa
Keyword(s):  
Electric Field ◽  
Field Data ◽  
Empirical Relationship ◽  
Hf Radar ◽  
Velocity Variation ◽  
Electron Drift ◽  
Abstract Data ◽  
E Region ◽  
The Relationship ◽  
Cosine Law

Abstract. Data collected by the Stokkseyri SuperDARN HF radar simultaneously at short and far ranges are used to investigate the relationship between the velocity of E-region HF echoes, E×B electron drift and the isothermal ion-acoustic speed CS. The work targets large E×B drifts of >1000 m s−1 and observations predominantly along the flow. By considering the EISCAT temperature and electric field data, an empirical relationship between the E×B drift velocity and CS is established for a number of ionospheric heights. For the Stokkseyri HF radar beams oriented roughly along the E×B direction, the observed E-region HF velocities are consistent with the CS values at the bottom of the electrojet but not at its center. For a subset of the data with smooth and consistent velocity variation with the beam azimuth at both short and far radar ranges the velocity varies according to the cosine law. For the E-region echoes, the proportionality coefficient in the cosine law is consistent with the CS values at the bottom of the electrojet. For these events, the E-region velocity maximum is shown to be between the E×B and electric field directions. The statistically average shift is ~20° and it increases slightly with the E×B magnitude.

UNDERWATER BARRED BEACH PROFILE TRANSFORMATION UNDER DIFFERENT WAVES CONDITIONS

2017 ◽  
Author(s):  
Olga Kuznetsova ◽  
Olga Kuznetsova ◽  
Yana Saprykina ◽  
Yana Saprykina ◽  
Boris Divinsky ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Coastal Zone ◽  
Wave Height ◽  
Wave Energy ◽  
Wave Period ◽  
Beach Profile ◽  
Infragravity Waves ◽  
Wave Parameters ◽  
Mean Wave Period

Based on numerical modelling evolution of beach under waves with height 1,0-1,5 m and period 7,5 and 10,6 sec as well as spectral wave parameters varying cross-shore analysed. The beach reformation of coastal zone relief is spatially uneven. It is established that upper part of underwater beach profile become terraced and width of the terrace is in direct pro-portion to wave height and period on the seaward boundary but inversely to angle of wave energy spreading. In addition it was ascertain that the greatest transfiguration of profile was accompanied by existence of bound infragravity waves, smaller part of its energy and shorter mean wave period as well as more significant roller energy.

Evolution of solitary waves in a two-pycnocline system

2009 ◽  
Vol 642 ◽  
pp. 235-277 ◽  
Author(s):  
M. NITSCHE ◽  
P. D. WEIDMAN ◽  
R. GRIMSHAW ◽  
M. GHRIST ◽  
B. FORNBERG
Keyword(s):  
Solitary Waves ◽  
Initial Conditions ◽  
Oscillation Period ◽  
Resonance Phenomenon ◽  
Numerical Code ◽  
Asymptotic Model ◽  
Narrow Region ◽  
Near Resonance ◽  
Long Time ◽  
The Waves

Over two decades ago, some numerical studies and laboratory experiments identified the phenomenon of leapfrogging internal solitary waves located on separated pycnoclines. We revisit this problem to explore the behaviour of the near resonance phenomenon. We have developed a numerical code to follow the long-time inviscid evolution of isolated mode-two disturbances on two separated pycnoclines in a three-layer stratified fluid bounded by rigid horizontal top and bottom walls. We study the dependence of the solution on input system parameters, namely the three fluid densities and the two interface thicknesses, for fixed initial conditions describing isolated mode-two disturbances on each pycnocline. For most parameter values, the initial disturbances separate immediately and evolve into solitary waves, each with a distinct speed. However, in a narrow region of parameter space, the waves pair up and oscillate for some time in leapfrog fashion with a nearly equal average speed. The motion is only quasi-periodic, as each wave loses energy into its respective dispersive tail, which causes the spatial oscillation magnitude and period to increase until the waves eventually separate. We record the separation time, oscillation period and magnitude, and the final amplitudes and celerity of the separated waves as a function of the input parameters, and give evidence that no perfect periodic solutions occur. A simple asymptotic model is developed to aid in interpretation of the numerical results.

scholarly journals Knowledge Management and Organizational Culture: An Exploratory Study

2013 ◽  
Vol 3 (1) ◽  
pp. 65-77 ◽  
Author(s):  
Bing Li ◽  
Jianpeng Zhang ◽  
Xiaoxia Zhang
Keyword(s):  
Organizational Culture ◽  
Knowledge Management ◽  
Management Practices ◽  
Empirical Relationship ◽  
Organizational Factors ◽  
Equation Modeling ◽  
Specific Situation ◽  
Knowledge Management Practices ◽  
Cultural Traits ◽  
The Relationship

Abstract Purpose of the article Knowledge has been considered as the strategic assets and become the source of competitive advantage in organizations. Knowledge management thus receives the extraordinary attention from the top management. Many organizational factors have influences on knowledge management practices. This paper attempts to explore the empirical relationship between knowledge management and organizational culture in the specific situation of China’s commercial banking industry. Methodology/methods The relationship between knowledge management and organizational culture is quantitatively investigated by surveying bank managers. The scale of SECI modes is used to measure knowledge management process and the scale of Denison Organizational Culture Survey (DOCS) is used to measure organizational culture. We explore the underlying relationship by employing the statistical analyses such as correlation, regression and structural equation modeling. Scientific aim The research aims at testing the relationship between knowledge management and organizational culture, and furthermore if there exist linkages between cultural traits and SECI modes. Findings The results of the empirical study confirm the great and positive effect that organizational culture has on knowledge management. Different cultural traits contribute to different SECI modes. Conclusions For obtaining successful knowledge management practices in organizations, it is better to concern about the relationship between knowledge management and organizational culture. The limitation in the paper is the sampling size, which will be solved by an industry-wide survey in our future research.

Towards a Theory of Suicide: The Case for Modern Fatalism

1981 ◽  
Vol 11 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Dennis L. Peck
Keyword(s):  
Content Analysis ◽  
Empirical Relationship ◽  
Social Condition ◽  
Case Histories ◽  
Specific Population ◽  
Suicide Notes ◽  
Theoretical Statement ◽  
The Relationship

This paper explores the empirical relationship between fatalism and suicide in a population of youthful victims. Content analysis of case histories and suicide notes was conducted for 132 individuals between the ages of twelve and thirty-four. Almost one-third (N = 43) of the youthful suicide victims were found to have experienced fatalistic thought-ways prior to their death. A model of fatalistic suicide based upon salient interdisciplinary observations consistent with a fatalistic explanation of youthful suicide is presented. Results are discussed relative to a specific population of victims in the light of a theoretical statement promulgating the relationship between a fatalistic social condition and youthful suicide.

A Dynamic Theory of Populism in Power

2021 ◽  
Author(s):  
Julio F. Carrión
Keyword(s):  
Regime Change ◽  
Dynamic Theory ◽  
Empirical Relationship ◽  
The United States ◽  
Democratic Governance ◽  
Theory Of Change ◽  
Popular Participation ◽  
The Andes ◽  
The Impact ◽  
The Relationship

The relationship between populism and democracy is a hotly debated topic. Some believe that populism is inherently bad for democracy because it is anti-pluralist and confrontational. Others argue that populism can reinvigorate worn-out democracies in need of an infusion of greater popular participation. This book advances this debate by examining the empirical relationship between populism in power and democracy. Does populism in power always lead to regime change, that is, the demise of democracy? The answer is no. The impact of populism on democracy depends on the variety of populism in power: the worst outcomes in democratic governance are found under unconstrained populism. This book discusses the conditions that explain how populism becomes unconstrained, and advances a dynamic theory of change that shows how the late victories of populists build on early ones, resulting in greater power asymmetries. The book analyzes five populist presidencies in the Andes. In four of them (Bolivia, Ecuador, Peru, and Venezuela), populism became unconstrained and regime change followed. In one case, Colombia, populism in power was contained and democracy survived. The concluding chapter places the Andean cases in comparative perspective and discusses how unconstrained populism in other cases (Nicaragua and Hungary) also lead to the end of electoral democracy. Where populism in power was constrained (Honduras and the United States), regime change did not materialize. This book advances a theory of populism that help us understand how democracies transition into non-democracies. To that extent, the book illuminates the processes of democratic erosion in our time.

The Relationship between Strength and Abrasion Characterizations in Granite Building Stones

2021 ◽  
pp. qjegh2020-045
Author(s):  
A. Cheshomi ◽  
M. Moradizadeh
Keyword(s):  
Dimensionless Parameter ◽  
Empirical Relationship ◽  
Building Stones ◽  
Brazilian Tensile Strength ◽  
Strength Parameters ◽  
Empirical Relationships ◽  
Quartz Content ◽  
Simultaneous Impact ◽  
Rock Abrasion ◽  
The Relationship

The wear of cutting blades during the preparation of building stones is an inevitable issue that occurs due to the contact of the blade with rock components. The present study aims to investigate the feasibility of proposing experimental relations of strength parameters and mineralogical hardness with Cerchar and LCPC tests. For this purpose, 18 samples of granite building stones were selected and Equivalent Quartz Content (EQC), compressive and Brazilian tensile strength (UCS and BTS), Cerchar, and LCPC abrasivity indices (CAI and LAC) were determined. The results showed the lack of any significant relationship between strength and abrasion properties. However, when evaluating the simultaneous impact of EQC and UCS using the rock abrasion index (RAI=UCS×EQC), significant valid empirical relationships between RAI-CAI and RAI-LAC were derived. To investigate the simultaneous effect of UCS, BTS, and EQC, a dimensionless parameter, i.e. modified rock abrasion index (MRAI=(UCSBTS)×EQC) was introduced. Moreover, it was found that the empirical relationship between MRAI-CAI was more significant and valid than the previous relations. Verification of the proposed relationship with the values of other researchers and 6 new samples for estimating CAI and LAC based on UCS, BTS, and EQC was found to be highly accurate for granite building stones.

scholarly journals The importance of entrainment and bulking on debris flow runout modeling: examples from the Swiss Alps

2015 ◽  
Vol 15 (11) ◽  
pp. 2569-2583 ◽  
Author(s):  
F. Frank ◽  
B. W. McArdell ◽  
C. Huggel ◽  
A. Vieli
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Field Data ◽  
Average Rate ◽  
Hazard Analysis ◽  
Maximum Shear Stress ◽  
Empirical Relationship ◽  
Swiss Alps ◽  
Field Site ◽  
Practical Applications

Abstract. This study describes an investigation of channel-bed entrainment of sediment by debris flows. An entrainment model, developed using field data from debris flows at the Illgraben catchment, Switzerland, was incorporated into the existing RAMMS debris-flow model, which solves the 2-D shallow-water equations for granular flows. In the entrainment model, an empirical relationship between maximum shear stress and measured erosion is used to determine the maximum potential erosion depth. Additionally, the average rate of erosion, measured at the same field site, is used to constrain the erosion rate. The model predicts plausible erosion values in comparison with field data from highly erosive debris flow events at the Spreitgraben torrent channel, Switzerland in 2010, without any adjustment to the coefficients in the entrainment model. We find that by including bulking due to entrainment (e.g., by channel erosion) in runout models a more realistic flow pattern is produced than in simulations where entrainment is not included. In detail, simulations without entrainment show more lateral outflow from the channel where it has not been observed in the field. Therefore the entrainment model may be especially useful for practical applications such as hazard analysis and mapping, as well as scientific case studies of erosive debris flows.

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