Determination of Dynamic Forces From Wave Motion Measurements

1986 ◽  
Vol 53 (1) ◽  
pp. 61-68 ◽  
Author(s):  
J. E. Michaels ◽  
Yih-Hsing Pao
Keyword(s):  
Seismic Data ◽  
Wave Motion ◽  
Deconvolution Method ◽  
Source Characterization ◽  
Characterization Methods ◽  
Earthquake Sources ◽  
Dynamic Forces ◽  
Time Histories ◽  
Motion Measurements

An experimental method has been developed for generating oblique forces with known orientations and time histories. Recorded signals from several forces were analyzed by an iterative deconvolution method to determine their orientations and time histories. The recovered values agree closely with the exact ones for these controlled sources. These experiments are a valuable test of source characterization methods that may be applied to seismic data from earthquake sources or to signals recorded from the acoustic emission of cracks.

THE DETERMINATION OF DIGITAL WIENER FILTERS BY MEANS OF GRADIENT METHODS

Geophysics ◽  
1973 ◽  
Vol 38 (2) ◽  
pp. 310-326 ◽  
Author(s):  
R. J. Wang ◽  
S. Treitel
Keyword(s):  
Seismic Data ◽  
High Speed ◽  
Gradient Methods ◽  
Wiener Filter ◽  
Gradient Algorithm ◽  
Rapid Convergence ◽  
True Solution ◽  
Peripheral Device ◽  
Wiener Filters

The normal equations for the discrete Wiener filter are conventionally solved with Levinson’s algorithm. The resultant solutions are exact except for numerical roundoff. In many instances, approximate rather than exact solutions satisfy seismologists’ requirements. The so‐called “gradient” or “steepest descent” iteration techniques can be used to produce approximate filters at computing speeds significantly higher than those achievable with Levinson’s method. Moreover, gradient schemes are well suited for implementation on a digital computer provided with a floating‐point array processor (i.e., a high‐speed peripheral device designed to carry out a specific set of multiply‐and‐add operations). Levinson’s method (1947) cannot be programmed efficiently for such special‐purpose hardware, and this consideration renders the use of gradient schemes even more attractive. It is, of course, advisable to utilize a gradient algorithm which generally provides rapid convergence to the true solution. The “conjugate‐gradient” method of Hestenes (1956) is one of a family of algorithms having this property. Experimental calculations performed with real seismic data indicate that adequate filter approximations are obtainable at a fraction of the computer cost required for use of Levinson’s algorithm.

A method of ground‐roll elimination

Geophysics ◽  
1988 ◽  
Vol 53 (7) ◽  
pp. 894-902 ◽  
Author(s):  
Ruhi Saatçilar ◽  
Nezihi Canitez
Keyword(s):  
Seismic Data ◽  
Seismic Reflection ◽  
Wave Motion ◽  
Frequency Interval ◽  
Vertical Resolution ◽  
Matched Filters ◽  
One Dimensional ◽  
Frequency Bands ◽  
Ground Roll ◽  
Seismic Reflections

Amplitude‐ and frequency‐modulated wave motion constitute the ground‐roll noise in seismic reflection prospecting. Hence, it is possible to eliminate ground roll by applying one‐dimensional, linear frequency‐modulated matched filters. These filters effectively attenuate the ground‐roll energy without damaging the signal wavelet inside or outside the ground roll’s frequency interval. When the frequency bands of seismic reflections and ground roll overlap, the new filters eliminate the ground roll more effectively than conventional frequency and multichannel filters without affecting the vertical resolution of the seismic data.

Preliminary determination of crustal structure in the Katmai National Monument, Alaska

1967 ◽  
Vol 57 (6) ◽  
pp. 1367-1392
Author(s):  
Eduard Berg ◽  
Susumu Kubota ◽  
Jurgen Kienle
Keyword(s):  
Crustal Structure ◽  
Seismic Data ◽  
Bouguer Anomaly ◽  
Volcanic Area ◽  
Average Depth ◽  
S Wave ◽  
Contour Map ◽  
Alaska Peninsula ◽  
National Monument

Abstract Seismic and gravity observations were carried out in the active volcanic area of Katmai in the summer of 1965. A determination of hypocenters has been aftempted using S and P arrivals at a station located at Kodiak and two stations located in the Monument. However, in most cases, deviations of travel times from the Jeffreys-Bullen tables were rather large. Therefore hypocenters are not well located. A method based on P- and S-wave arrivals yields a Poisson's ratio of 0.3 for the upper part of the mantle under Katmai. This higher value is probably due to the magma formation. The average depth to the Moho from seismic data in the same area is 38 km and 32 km under Kodiak. Using Woollard's relation between Bouguer anomaly and depth to the Moho, a small mountain root under the volcanoes with a depth of 34 km was found dipping gently up to 31 km on the NW side. The active volcanic cones are located along an uplift block. This block is associated with a 35 mgal Bouguer anomaly. The Bouguer anomaly contour map for the Alaska Peninsula is given and an interpretation attempted.

scholarly journals Photocatalytic Activity: Experimental Features to Report in Heterogeneous Photocatalysis

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1990 ◽  
Author(s):  
Md. Hoque ◽  
Marcelo Guzman
Keyword(s):  
Reaction Rate ◽  
Monochromatic Light ◽  
Heterogeneous Photocatalysis ◽  
Research Articles ◽  
Quantum Yields ◽  
Characterization Methods ◽  
Valuable Data ◽  
Photocatalytic Activities ◽  
Scientific Papers

Heterogeneous photocatalysis is a prominent area of research with major applications in solar energy conversion, air pollution mitigation, and removal of contaminants from water. A large number of scientific papers related to the photocatalysis field and its environmental applications are published in different journals specializing in materials and nanomaterials. However, many problems exist in the conception of papers by authors unfamiliar with standard characterization methods of photocatalysts as well as with the procedures needed to determine photocatalytic activities based on the determination of “apparent quantum efficiencies” within a wavelength interval or “apparent quantum yields” in the case of using monochromatic light. In this regard, an astonishing number of recent research articles include claims of highly efficient (photo)catalysts or similar terms about materials with superior or enhanced efficiency for a given reaction without proper experimental support. Consequently, the comparison of the efficiencies of photocatalysts may result as being meaningless, especially when reports are only based on expressions determining (1) a reaction rate per weight of catalyst or its surface area, (2) quantum efficiencies or quantum yields, and (3) turnover frequencies or turnover numbers. Herein, we summarize the standards needed for reporting valuable data in photocatalysis and highlight some common discrepancies found in the literature. This work should inform researchers interested in reporting photocatalysis projects about the correct procedures for collecting experimental data and properly characterizing the materials by providing examples and key supporting literature.

Experimental Determination of Wheel and Guiding Forces on the Tracks

2015 ◽  
Vol 732 ◽  
pp. 203-206
Author(s):  
Lubos Pazdera ◽  
Jaroslav Smutny ◽  
Libor Topolář
Keyword(s):  
Experimental Determination ◽  
Vertical Direction ◽  
Railway Track ◽  
Experimental Basis ◽  
Force Interaction ◽  
Dynamic Forces ◽  
Passing Train ◽  
Strain Measures

Force interaction between a railway track and a vehicle affects the safety, comfort, and last but not least, economical maintenance. Train of wagons incidence on track in both transversal and vertical direction is simplified by qualifying of force wheel (FQ), guiding (FY) and perpendicular and transverse acceleration. An experimental basis for dynamic determination of vertical, FQ, and lateral, FY, forces at the wheel using strain measures in the foot of the rail is given. Measurements of the dynamic forces during passing train are normally very costly and uneasy. These method consists of measuring strains at selected points of the rail profile is very simple and therefore interesting.

scholarly journals Structural vehicle impact loading

2013 ◽  
Vol 11 (3) ◽  
pp. 285-292
Author(s):  
Dragoslav Stojic ◽  
Stefan Conic
Keyword(s):  
Impact Analysis ◽  
Impact Loads ◽  
Structural Elements ◽  
Structural Element ◽  
Static Loads ◽  
Equivalent Static Loads ◽  
Vehicle Impact ◽  
Dynamic Forces ◽  
Force Intensity

In contemporary design, vehicle impact into the structures is paid great attention since they can be dominant, depending on the type of structure. The key issue in the vehicle impact analysis is the proper determination of intensity and way of action of dynamic forces on the structural element and its behavior after the imparted load. The Eurocodes, in the annexes provide recommendations for determination of force intensity depending on mass and velocity of the colliding vehicle. Equivalent static loads causing approximate effects on the structural elements are used as quite approximate and efficient methods. The paper comprises the analysis of deformation of columns having the same characteristics, exposed to impact loads via the equivalent static loads, depending on the stress state in columns, and a comparative analysis has been done.

THREE‐DIMENSIONAL SEISMIC METHOD

Geophysics ◽  
1972 ◽  
Vol 37 (3) ◽  
pp. 417-430 ◽  
Author(s):  
G. G. Walton
Keyword(s):  
Seismic Data ◽  
Average Velocity ◽  
Three Dimensional ◽  
Data Gathering ◽  
Seismic Method ◽  
Dynamic Display ◽  
Profile Line ◽  
Production Problems ◽  
Dense Coverage

The three‐dimensional seismic method is a different way of gathering and presenting seismic data. Instead of showing the subsurface beneath a profile line, 3-D displays give an, areal picture from the shallowest reflector to the deepest one that can be found seismically. Data are collected in the field with cross‐spreads that provide over 2000 evenly spaced depth points on each reflecting interface. Several variations of the cross‐spread technique give the same subsurface coverage while providing flexibility in data gathering. Because of the dense coverage, the method is best suited for problems requiring great detail, such as production problems. The usual presentation of 3-D data is a visual, moving display of emerging wavefronts covering four sq mi of surface. From this dynamic display, average velocity to each reflector and the dip direction and magnitude can be computed. The method has proved especially useful for the recognition of faults and determination of fault directions.

Application of Slender-Body Theory

1957 ◽  
Vol 1 (04) ◽  
pp. 40-49
Author(s):  
Paul Kaplan
Keyword(s):  
Slender Body ◽  
Vertical Force ◽  
Regular Waves ◽  
Slender Body Theory ◽  
Surface Theory ◽  
Surface Ship ◽  
Submerged Body ◽  
Dynamic Forces ◽  
Body Theory

The vertical force and pitching moment acting on a slender submerged body and on a surface ship moving normal to the crests of regular waves are found by application of slender-body theory, which utilizes two-dimensional crossflow concepts. Application of the same techniques also results in the evaluation of the dynamic forces and moments resulting from the heaving and pitching motions of the ship, which corrected previous errors in other works, and agreed with the results of specialized calculations of Havelock and Has-kind. An outline of a rational theory, which unites slender-body theory and linearized free-surface theory, for the determination of the forces, moments and motions of surface ships, is also included.

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