Back-Calculation Procedures of Material Properties from Flexural Tests

2011 ◽  
pp. 301-316
Keyword(s):  
Material Properties ◽  
Back Calculation ◽  
Flexural Tests ◽  
Calculation Procedures

Thermal Stress Analysis Based on Equivalent Age of Heterogeneous Mass Concrete

2013 ◽  
Vol 353-356 ◽  
pp. 3256-3262
Author(s):  
Pei Fang Su ◽  
Xing Li Lu
Keyword(s):  
Mechanical Properties ◽  
Thermal Stress ◽  
Material Properties ◽  
Simulation Method ◽  
Temperature History ◽  
Mass Concrete ◽  
Mechanical Parameters ◽  
Equivalent Age ◽  
Fem Method ◽  
Calculation Procedures

In order to analysis thermal stress of mass concrete accurately, material properties of mass concrete are studied by numerical simulation method, and the equivalent age is introduced to describe the mechanical properties of concrete. The calculation models of concrete mechanical parameters are summarized, and then the calculation procedures are established on the basis of equivalent age. In this way, the temperature and temperature history are considered in these models. Meanwhile, the governing equation and computer program of the thermal stress based on the equivalent age are developed. The comparison of the numerical example using proposed method and conventional FEM method shows that the proposed method performs more adaptable and accurate.

Visco-Elastic Back-Calculation of Traffic Speed Deflectometer Measurements

2019 ◽  
Vol 2673 (12) ◽  
pp. 439-448 ◽  
Author(s):  
Christoffer P. Nielsen
Keyword(s):  
Calculation Procedure ◽  
Falling Weight Deflectometer ◽  
Calculation Algorithm ◽  
Structural Evaluation ◽  
Driving Speed ◽  
Back Calculation ◽  
Traffic Speed ◽  
Falling Weight ◽  
Calculation Procedures ◽  
Project Level

The traffic speed deflectometer (TSD) has proven a valuable tool for network level structural evaluation. At the project level, however, the use of TSD data is still quite limited. An obstacle to the use of TSD at the project level is that the standard approaches to back-calculation of pavement properties are based on the falling weight deflectometer (FWD). The FWD experiment is similar, but not equivalent, to the TSD experiment, and therefore it is not straightforward to apply the traditional FWD back-calculation procedures to TSD data. In this paper, a TSD-specific back-calculation procedure is presented. The procedure is based on a layered linear visco-elastic pavement model and takes the driving speed of the vehicle into account. This is in contrast to most existing back-calculation procedures, which treat the problem as static and the pavement as purely elastic. The developed back-calculation procedure is tested on both simulated and real TSD data. The real TSD measurements exhibit significant effects of damping and visco-elasticity. The back-calculation algorithm is able to capture these effects and yields model fits in excellent agreement with the measured values.

Comparison of four methods of back-calculating growth using otoliths of a European barbel, Barbus sclateri (GÜnther) (Pisces : Cyprinidae)

1999 ◽  
Vol 50 (1) ◽  
pp. 83 ◽  
Author(s):  
Carmelo Escot ◽  
Carlos Granado-Lorencio
Keyword(s):  
Natural Populations ◽  
Regression Method ◽  
Fish Length ◽  
Direct Proportion ◽  
Allometric Relationship ◽  
Back Calculation ◽  
Para Determinar ◽  
The Relationship ◽  
Simple Regression ◽  
Calculation Procedures

The allometric relationship between fish length and otolith radius was determined for a European barbel, Barbus sclateri, from two natural populations. The relationship was significantly different between populations, but did not differ between females and males. The ages of the fish were determined from the otoliths, and this was used to evaluate four back-calculation procedures: Monastyrsky’s method of direct proportion; two by intercept-corrected direct proportion (Fraser-Lee’s method and the biological intercept method); and the simple regression method. The biological intercept method provided the most reliable estimates of fish lengths at previous ages when otoliths were used. Lengths back-calculated from earlier annuli of older fish were quite different from observed lengths for each age and from lengths back-calculated from recent annuli. Resumen. A dos poblaciones naturales de barbo europeo, Barbus sclateri, se les determinó la relación alométrica entre la longitud del pez y el radio del otolito. Esta relación fue significativamente diferente entre las dos localidades geográficas, e igual entre hembras y machos. Se utilizó los otolitos para determinar la edad de los peces y para evaluar cuatro procedimientos de retrocálculo: el método de Monastyrsky de proporción directa; dos de proporción directa en los que se corrige la intersección, el método de Fraser-Lee y el de intersección biológica; y el método de regresión simple. El método de intersección biológica ofrece las estimas más reales de la longitud del pez en las edades anteriores a la captura. Por otro lado, las longitudes retrocalculadas a partir de los annuli formados en primer lugar de los ejemplares más viejos, fueron diferentes a las longitudes observadas en cada edad y a las longitudes retrocalculadas a partir de los annuli formados más recientemente.

Size-Biased Survival in Steelhead Trout (Oncorhynchus mykiss): Back-Calculated Lengths from Adults' Scales Compared to Migrating Smolts at the Keogh River, British Columbia

1989 ◽  
Vol 46 (11) ◽  
pp. 1853-1858 ◽  
Author(s):  
B. R. Ward ◽  
P. A. Slaney ◽  
A. R. Facchin ◽  
R. W. Land
Keyword(s):  
Salt Water ◽  
Survival Rates ◽  
Length Distribution ◽  
Adult Survival ◽  
Steelhead Trout ◽  
Island Size ◽  
Back Calculation ◽  
Males And Females ◽  
The Mean ◽  
Calculation Procedures

Lengths of wild, winter-run steelhead smolts, estimated by back-calculation procedures from adults' scales, were compared with observed lengths of migrating smolts sampled near the mouth of the Keogh River, Vancouver Island. Size-biased smolt-to-adult survival rates were estimated for several length categories by utilizing length frequencies from observed smolts, smolt length frequencies which were back calculated from adults' scales, smolt yield, and adult returns. Back-calculated smolt length (BSL) of adults returning from smolts of 1977 to 1982 averaged 193 mm compared to 176 mm for observed smolt length (OSL). Mean BSL was larger than OSL in every year. Adults from odd-numbered smolt years had larger BSL than adults from even-numbered smolt years similar to the pattern in OSL. BSL increased with increased years spent in salt water, based on ageing adults' scales. Males and females had different BSL based on number of years spent in fresh water and salt water, although they exhibited the same mean BSL overall. The smolt-to-adult survival estimates were in close agreement with previous estimates derived from the mean OSL. Predictability of survival in the ocean based on the length of smolts was extended over a broad range of the length distribution of wild steelhead smolts.

On the stability of laminar boundary-layer flow over a flat plate with a compliant surface

1988 ◽  
Vol 197 ◽  
pp. 201-240 ◽  
Author(s):  
P. K. Sen ◽  
D. S. Arora
Keyword(s):  
Material Properties ◽  
Kinematic Model ◽  
Compliant Surface ◽  
Wall Boundary Conditions ◽  
Back Calculation ◽  
Transitional Mode ◽  
Tollmien Schlichting ◽  
Layer Flow ◽  
Specific Material ◽  
The Stability

The problem has been examined using a kinematic model for wall pliability, wherein a kinematic postulation of the wall boundary conditions is made. A form of the normalized wall-displacement and its phase are used as additional parameters in an extended eigenvalue problem. Using this technique the entire gamut of possibilities regarding stability of flow past (normally) pliable walls can be examined, yet without recourse to any specific material properties for the wall. Rather, the results based on the kinematic model can be used to back-calculate the material properties corresponding to any chosen model for the dynamics of the wall. A sample back calculation is discussed herein for the Benjamin–Landahl wall model, and based on this some predictions are made regarding both stabilization of the flow and physical realizability of modes. It is believed that the kinematic model will prove useful in further understanding of the problem, and in the design of stabilizing coatings.The results show that there are three important ‘mode classes’ (distinct from ‘modes’), namely the Tollmien–Schlichting (TS), resonant (R) and Kelvin–Helmholtz (KH). Whereas the TS and R mode classes broadly agree with modes bearing similar names as found by earlier workers, the present KH mode class is difficult to classify based on earlier work. Moreover, there are also important transitional mode classes in the regions of bifurcations of the regular mode classes.Two important concepts evolve in connection with the TS and R mode classes, namely the existence of ‘stable pockets’ for the former and ‘unstable pockets’ for the latter. It is also confirmed herein that there are conflicting requirements on the damping d to stabilize TS and R modes. Considering these points it has been suggested that TS and R modes be avoided by keeping soft surfaces as compliant coatings. However, this in turn leads to instabilities from one of the transitional mode classes. It is also seen that a soft surface that is also marginally active (i.e. having a small negative value of d) could render even better stabilization.

Effect of Smolt Size on Smolt-to-Adult Survival for Chilko Lake Sockeye Salmon (Oncorhynchus nerka)

1991 ◽  
Vol 48 (6) ◽  
pp. 988-994 ◽  
Author(s):  
M. A. Henderson ◽  
A. J. Cass
Keyword(s):  
Sockeye Salmon ◽  
Interannual Variation ◽  
Oncorhynchus Nerka ◽  
Fork Length ◽  
Adult Survival ◽  
Threefold Increase ◽  
Limited Variation ◽  
Back Calculation ◽  
The Mean ◽  
Calculation Procedures

Three approaches were used to test the hypothesis that smolt-to-adult survival is independent of smolt size for Chilko Lake sockeye salmon (Oncorhynchus nerka). The mean distance between the focus of the scale and the first annulus, a reliable indicator of smolt size, was greater for adult scales than for smolt scales from the same brood year in two of the three years we examined. This indicated a higher smolt-to-adult survival for larger smolts in these brood years. The abundance of smolts of different fork lengths, based on back-calculation procedures from adult scales, was compared with the abundance of smolts of different fork lengths at the time of outmigration within brood years. In all three years studied, there was a two- to threefold increase in smolt-to-adult survival as smolt length increased. However, there was no significant relationship between smolt-to-adult survival and mean annual smolt fork length based on a 34-yr time series; this lack of relationship was probably caused by limited variation in mean annual smolt fork length over the 34-yr period and other variables, independent of smolt size, that affect survival and exhibit considerable interannual variation.

Grain boundary segregation in metals

1992 ◽  
Vol 50 (2) ◽  
pp. 1204-1205
Author(s):  
C.L. Briant
Keyword(s):  
Fracture Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Material Properties ◽  
Electron Spectroscopy ◽  
High Vacuum ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Local Concentration ◽  
The One

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.

Relationships Between Grain Boundary Structure and Material Properties

1980 ◽  
Vol 38 ◽  
pp. 366-369
Author(s):  
Brian Ralph ◽  
Barlow Claire ◽  
Nicola Ecob
Keyword(s):  
Grain Boundary ◽  
Material Properties ◽  
Main Property ◽  
Grain Structure ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Property Changes

This brief review seeks to summarize some of the main property changes which may be induced by altering the grain structure of materials. Where appropriate an interpretation is given of these changes in terms of current theories of grain boundary structure, and some examples from current studies are presented at the end of this paper.

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