An alternative method for a reliable estimation of seismicity with an application in Greece and the surrounding area

1999 ◽  
Vol 89 (1) ◽  
pp. 111-119
Author(s):  
C. Papazachos
Keyword(s):  
Material Properties ◽  
B Value ◽  
Linear Constraints ◽  
Return Periods ◽  
Surrounding Area ◽  
Main Hypothesis ◽  
B Values ◽  
Alternative Method ◽  
Occam’S Inversion ◽  
Good Agreement

Abstract An alternative method is proposed for the robust estimation of a and b values of the Gutenberg-Richter relation. The main hypothesis is that b values depend on material properties and the seismotectonic setting and therefore should vary relatively smoothly in space. As far as the a values are concerned, more sharp variations are allowed because these values determine the seismicity level, once the b value is fixed. The study area is organized into a grid, and the a and b values are simultaneously determined for the whole grid by solving an appropriate linear system. Smooth b variations are imposed by introducing additional linear constraints, similar to the Occam's inversion used in tomography studies. The method is applied to Greece and the surrounding area, which is a high seismicity area. The results are in very good agreement with previous studies and further enhance our knowledge for the study area. Moreover, additional seismicity measures (return periods, probabilities, etc.) are estimated robustly because they depend on the a and b values obtained for this area.

Seismotectonic maps of the European area

1975 ◽  
Vol 65 (6) ◽  
pp. 1721-1732
Author(s):  
K. L. Kaila ◽  
N. Madhava Rao
Keyword(s):  
B Value ◽  
Regression Curve ◽  
B Values ◽  
Regression Curves ◽  
European Area ◽  
A Value ◽  
The Alps ◽  
Seismotectonic Map ◽  
Good Agreement ◽  
Regional Tectonics

abstract Seismicity maps based on A value, b value, and return period for earthquakes with magnitude 6 and above have been prepared for the European area using the Kaila and Narain (1971) method. For the preparation of these maps, a modified relation A = 6.36b − 1.00 has been used instead of the earlier relation where A and b are constants in the cumulative regression curve represented by log N = A − bM. The A-value seismicity map also shows regional tectonics superimposed on it, thus yielding the seismotectonic map of Europe. These seismicity maps reveal that the European area consists of seven main high seismic activity zones named as the Balkan high, the Aegean high, the Apennine-sicilian high, the Alps high, the Carpathian high, the Saharan-Pyrenees high and the Iceland-Arctic high which are described in detail with their relationship to regional tectonics. The b values determined by the new method and shown on the b-value seismicity map are compared with those determined by other workers using earthquake regression curves for various regions of Europe and they show a very good agreement with each other.

Device Modeling of a-Si:H Alloy Solar Cells: Calibration Procedure for Determination of Model Input Parameters

1998 ◽  
Vol 507 ◽  
Author(s):  
M. Zeman ◽  
R.A.C.M.M. Van Swaaij ◽  
E. Schroten ◽  
L.L.A. Vosteen ◽  
J.W. Metselaar
Keyword(s):  
Solar Cell ◽  
Material Properties ◽  
Calibration Procedure ◽  
Model Parameters ◽  
Model Input ◽  
A Value ◽  
Input Parameters ◽  
Simulated Material ◽  
Good Agreement

ABSTRACTA calibration procedure for determining the model input parameters of standard a-Si:H layers, which comprise a single junction a-Si:H solar cell, is presented. The calibration procedure consists of: i) deposition of the separate layers, ii) measurement of the material properties, iii) fitting the model parameters to match the measured properties, iv) simulation of test devices and comparison with experimental results. The inverse modeling procedure was used to extract values of the most influential model parameters by fitting the simulated material properties to the measured ones. In case of doped layers the extracted values of the characteristic energies of exponentially decaying tail states are much higher than the values reported in literature. Using the extracted values of model parameters a good agreement between the measured and calculated characteristics of a reference solar cell was reached. The presented procedure could not solve directly an important issue concerning a value of the mobility gap in a-Si:H alloys.

Earthquake sequences and b values in the southeast United States

1974 ◽  
Vol 64 (1) ◽  
pp. 267-273
Author(s):  
Leland Timothy Long
Keyword(s):  
United States ◽  
South Carolina ◽  
B Value ◽  
Earthquake Activity ◽  
Southeast United States ◽  
B Values ◽  
History Of ◽  
Earthquake Sequences ◽  
Foreshock Activity ◽  
Epicentral Region

abstract Aftershock and foreshock activity within 12 hr of the July 13, 1971 earthquake near Seneca, South Carolina, indicates a b value of 0.9 at ML = 3.0. Approximately 40 events recorded in a 5-day aftershock survey near Seneca indicate a b value of 1.7 at ML = 0.5. A sequence of over 40 events occurring west of McCormick, South Carolina, indicates a b value of 1.3 at ML = 2.4. The McCormick sequence was active for 4 months. Unlike the Seneca region, the McCormick region has a history of earthquake activity. Examinations of other published southeastern b values suggest that southeastern United States earthquakes originate from conditions of ambient stress which vary with epicentral region or magnitude.

Central Bursting and Optimal Die Profile for Axisymmetric Extrusion

1996 ◽  
Vol 118 (4) ◽  
pp. 579-584 ◽  
Author(s):  
N. Venkata Reddy ◽  
P. M. Dixit ◽  
G. K. Lal
Keyword(s):  
Material Properties ◽  
Process Conditions ◽  
Simple Criterion ◽  
Geometric Conditions ◽  
Die Profile ◽  
Good Agreement

A simple criterion for predicting the initiation of central burst in extrusion is proposed. The geometric conditions to avoid central bursting are predicted by using the proposed criterion under various process conditions and material properties. The optimal die profiles which minimize the extrusion power are also obtained for various process conditions. The mixed (pressure-velocity) formulation is used along with the Householder method to solve the resulting equations. It is shown that the optimal die profiles satisfy the conditions for prevention of central burst. The predictions based on the proposed criterion are in good agreement with the experimental observations and are in conformity with the results published earlier.

A New Method to Assess Ductility of CFT Box Columns with Binding Bars under Axial Compression

2012 ◽  
Vol 446-449 ◽  
pp. 78-81 ◽  
Author(s):  
Yue Ling Long ◽  
Jian Cai
Keyword(s):  
Experimental Data ◽  
Axial Compression ◽  
Material Properties ◽  
New Method ◽  
Box Columns ◽  
Good Agreement

A new method based on material properties instead of experimental data was proposed to assess the ductility of concrete-filled steel box columns with binding bars and those without binding bars. Comparison between ductility coefficients based on experimental data and the calculated values by the proposed method shows good agreement.

Prediction of Residual Stresses in Welded T- and I-Joints Using Inherent Strains

1996 ◽  
Vol 118 (2) ◽  
pp. 229-234 ◽  
Author(s):  
M. G. Yuan ◽  
Y. Ueda
Keyword(s):  
Residual Stresses ◽  
Material Properties ◽  
Strain Distribution ◽  
Elastic Analysis ◽  
Fillet Weld ◽  
Average Temperature ◽  
Input Material ◽  
Geometric Ratio ◽  
Inherent Strain ◽  
Good Agreement

In order to develop a predicting method of residual stresses in fillet welded T- and I-joints, a concept of inherent strain, being regarded as a source of the residual stresses, was introduced. With the proposed method, the residual stress of an interested weldment may be predicted by performing an elastic analysis, in which the inherent strain is replaced to equivalent distributed loads. The inherent strain distributions in various welded T- and I-joints were investigated by numerical simulations. The results showed that the inherent strains distributing in flange side and in web side of the several joints are almost the same. The inherent strains vary not only with the average temperature rise due to welding, but with the geometric ratio of the joints. Being simplified by a trapezoid curve, the inherent strain distribution in a fillet weld was expressed by formulas, in which heat input, material properties, and geometric dimensions were taken into account. Welding residual stresses in T- and I-joints, predicted by the proposed method employing the derived formulas, were compared with those obtained by thermal elasto-plastic analysis, and good agreement was recognized. The validity of the proposed method was also confirmed by experiments.

Two Foreshock Sequences Post Gulia and Wiemer (2019)

2020 ◽  
Vol 91 (5) ◽  
pp. 2843-2850 ◽  
Author(s):  
Kelian Dascher-Cousineau ◽  
Thorne Lay ◽  
Emily E. Brodsky
Keyword(s):  
Puerto Rico ◽  
Real Time ◽  
Exact Result ◽  
Monte Carlo Sampling ◽  
B Value ◽  
Aftershock Sequence ◽  
Traffic Light ◽  
B Values ◽  
Aftershock Sequences ◽  
Abrupt Changes

Abstract Recognizing earthquakes as foreshocks in real time would provide a valuable forecasting capability. In a recent study, Gulia and Wiemer (2019) proposed a traffic-light system that relies on abrupt changes in b-values relative to background values. The approach utilizes high-resolution earthquake catalogs to monitor localized regions around the largest events and distinguish foreshock sequences (reduced b-values) from aftershock sequences (increased b-values). The recent well-recorded earthquake foreshock sequences in Ridgecrest, California, and Maria Antonia, Puerto Rico, provide an opportunity to test the procedure. For Ridgecrest, our b-value time series indicates an elevated risk of a larger impending earthquake during the Mw 6.4 foreshock sequence and provides an ambiguous identification of the onset of the Mw 7.1 aftershock sequence. However, the exact result depends strongly on expert judgment. Monte Carlo sampling across a range of reasonable decisions most often results in ambiguous warning levels. In the case of the Puerto Rico sequence, we record significant drops in b-value prior to and following the largest event (Mw 6.4) in the sequence. The b-value has still not returned to background levels (12 February 2020). The Ridgecrest sequence roughly conforms to expectations; the Puerto Rico sequence will only do so if a larger event occurs in the future with an ensuing b-value increase. Any real-time implementation of this approach will require dense instrumentation, consistent (versioned) low completeness catalogs, well-calibrated maps of regionalized background b-values, systematic real-time catalog production, and robust decision making about the event source volumes to analyze.

Rate-Dependent Material Properties of Adhesively Bonded Joints - Must Have or Nice to Have?

2020 ◽  
Vol 858 ◽  
pp. 14-19
Author(s):  
Michael May
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Material Properties ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Crash Simulation ◽  
Adhesively Bonded Joints ◽  
Rate Dependent ◽  
Element Simulation ◽  
Good Agreement

In the context of automotive crash simulation, rate-dependent properties are sought for all materials undergoing deformation. Measuring rate-dependent properties of adhesively bonded joints is a challenging and associated with additional cost. This article assesses the need for having rate-dependent properties of adhesively bonded joints for the example of a typical automotive structure, an adhesively bonded metallic T-joint. Using Finite Element simulation it could be shown that good agreement between experiment and simulation was only achieved if rate-dependent properties were considered for the adhesive.

Mechanical Bending Simulation of Thin Stainless Steel by Using Isotropic and Orthotropic Properties

2011 ◽  
Vol 421 ◽  
pp. 312-315
Author(s):  
Somsak Siwadamrongpong ◽  
Usanee Kitkamthorn ◽  
Chaiyapak Sajjawattana
Keyword(s):  
Stainless Steel ◽  
Material Properties ◽  
Mechanical Response ◽  
Thin Sheet ◽  
Disk Drive ◽  
Simple Calculation ◽  
Orthotropic Materials ◽  
Mechanical Bending ◽  
Orthotropic Properties ◽  
Good Agreement

The most important factors in hard disk drive suspension manufacturing is the suspension preload, so call “gram load”. The suspensions were generally made from cold rolled stainless steel (SUS304). The suspensions were formed by mechanical forming and gram load was adjusted by mechanical bending until reached a specification. The material properties in mechanical bending simulation of thin stainless steel were usually as isotropic for simple calculation. But the properties of thin stainless steel should be defined as orthotropic materials. Therefore, this work aimed to study gram load results of using isotropic and orthotropic properties. The thin stainless sheet was cut and test for mechanical properties in rolling and transverse directions. The properties of the thin sheet were applied to simulation model. It was found that orthotropic material properties shows a good agreement with the experimental results more than using isotropic material properties. Therefore, the results of this work could be used to explain and predict the mechanical response on the suspension manufacturing.

Sign in / Sign up

Export Citation Format

Share Document