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  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Applied mechanics and materials Vol. 3-4 (Aug. 2006), p. 259-266 
    ISSN: 1662-7482
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper reports recent results from a set of experimental and computational studies of ductile flat fracture in modern gas pipeline steel. Experimental data from plain and notched cylindrical tensile bars and standard C(T) specimens together with damage mechanics theories have been used to capture the flat fracture characteristics of a gas pipeline steel of grade X100. The modelling was via finite element analysis using the Gurson-Tvergaard modified model (GTN) ofductile damage development. The assumption of effective material damage isotropy was sufficiently accurate to allow the transfer of data from the notched bars to predict, in a 2D model, the crack growth behaviour of the C(T) specimen. This was in spite of the considerable ovalisation of the bars at the end of their deformation. However, it was not possible to obtain similar accuracy with a 3D model of the C(T)test, even after a large number of attempts to adjust the values of the GTN parameters. This, and the anisotropic shape change in the tensile bars, suggests very strongly that the damage behaviour is so anisotropic that conventional models are not good enough for a full engineering description of the flat fracture behaviour. Suitable averaging (of shape) in the modelling of the notched bar data, and the companion averaging associated with the 2D model of the C(T) data provide a relatively fast way of transferring engineering data in the tests. There is a discussion of potential ways in which to incorporate 3D effects into the modelling for those purposes where the considerable increase in computational time (due to the microstructurally-sized finite elements needed to capture the damagebehaviour) is acceptable in order to include through-thickness effects
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Applied mechanics and materials Vol. 3-4 (Aug. 2006), p. 369-376 
    ISSN: 1662-7482
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Charpy upper shelf energy is widely used as a fracture controlling parameter to estimate the crack arrest/propagation performance of gas transportation pipeline steels. The measurement of this fracture criterion particularly for modern steels and its apportion into different components, i.e. fracture and non-related fracture energy, are of great importance for pipeline engineers. This paper presents the results of instrumented Charpy impact experiments on high-grade pipeline steel of grade X100. First, the instrumentation technique including the design and implementation of a strain gauge load-cell and the details of the data-recording scheme are reviewed. Next, the experimental data obtained from the Charpy impact machine so instrumented are presented and discussed. These include the test data from full and sub-sized Charpy V-notched specimens. The instrumented Charpy machine was able to capture the load history in full during the fracture process of the test specimens resulting in a smooth load-time response. This eliminated the need for filtering used in similar test techniques. From the recorded test data the hammer displacement, impact velocity and fracture energy were numerically calculated.The results showed that there was a significant drop in hammer velocity during the impact event. This resulted in a change in the fracture mode from dynamic to quasi-static which was more appreciable for full-size Charpy test samples. As a result, sub-sized specimens might be preferable for impact testing of this steel in order to guarantee the conditions of dynamic crack propagation in the specimen ligament. Accurate analysis of the instrumented impact test data showed that the ratio of crack initiation energy to propagation energy was around 30% for the X100 steel. It can be concluded that in impact testing of high-grade pipeline steel a significant portion of overall fracture energy is consumed in non-related fracture processes. This high fracture initiation energy should be accounted for if the current failure models are going to be used for toughness assessment of highstrength low-alloy gas pipeline steels
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2009-06-01
    Print ISSN: 0022-460X
    Electronic ISSN: 1095-8568
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Elsevier
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  • 4
    Publication Date: 2011-11-01
    Print ISSN: 0304-3894
    Electronic ISSN: 1873-3336
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Technology
    Published by Elsevier
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  • 5
    Publication Date: 2013-05-01
    Print ISSN: 0021-9991
    Electronic ISSN: 1090-2716
    Topics: Computer Science , Physics
    Published by Elsevier
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  • 6
    Publication Date: 2021-05-19
    Description: Population parameters of Whipfin silver-biddy (Gerres filamentosus) and Longtail silverbiddy (Gerres longirostris) were studied from January to December 2006 in three creeks (Markazi, Khalasi and Gabrik) of Hara protected area in Jask, Oman Sea. All fishes were sampled by boat trawl and beach seine. Growth parameters were determined using the monthly length–frequency parameters. The Mean total length was calculated at 6.2 and 5.4cm for Whipfin silver-biddy and Longtail silver-biddy. The values of L∞ and K for Whipfin silver-biddy were 16.8cm and 0.99 yr-1 and for Longtail silver-biddy, these were 15cm and 0.77 yr-1, respectively. The value of to was calculated at -0.12 year for both species. The longevity was estimated to be 3 years for Whipfin silver-biddy and 3.8 years for Longtail silver-biddy. The length-weight relationship were determined as W= 0.0088 L3.21 and W= 0.0087L 3.18 for Whipfin silver-biddy and Longtail silver-biddy, respectively. Results showed the fish were in their juvenile stage which emphasized the supporting roles of creeks for Gerridae as nursery ground.
    Description: Published
    Keywords: Gerres filamentosus ; Longtail ; Gerres longirostris ; Stock assessment ; Gerridae ; Growth ; Parameters ; Mortality ; Silver ; Area ; Population dynamic
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed
    Format: pp.139-150
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  • 7
    Publication Date: 2021-05-19
    Description: Qeshm Hara protected area is the largest and only biosphere reservoir in the Persian Gulf and Oman Sea that covered with mangroves. This study was aimed for population structure and species diversity of fishes in Hara protected area. Fishes were sampled monthly in 5 stations by fixed set-net(Moshta), drift set net (Khoorband), trawl survey and beach seine net method from September 2016 to August 2017. A totally of 16521 fish individuals were collected belong to 115 species, 92 genus and 57 family. The most frequent family of fishes were Leiognathidae (40.4 %), Mugilidae(11.4%), Pristigasteridae(5.9%), Clupeidae(5.8%), Gerreidae(5%), Sillaginidae(3.2%). The most dominant species was Nuchequula gerreoides with 6383 individuals (38.6%), along with Ilisha melastoma, Gerres oyena, Nematalosa nasus, Liza melinoptera, Liza klunzingeri, Osteomugil perusii , Sillago sihama, Upeneus sulphureus, Acanthopagrus arabicus and Pomadasys kaakan formed about 75 percent of the all collected fishes. Population dynamics of dominant fishes (16 species) were estimated using length frequency analysis, the results showed that the dominant were high growth rates and short-lived. Most fish have a life span of less than 10 months, only the Liza klunzigeri, Sillago sihama and Pomadasys kaakan have a mean life span of over one year in the studied area. The natural mortality rates of predominant fishes were generally higher than 1, except for Plotosus lineatus, which was 0.92. The fishes exploitation rates were above 0.5, except for 5 species of Ilisha melastoma, Nematalosa nasus, Nematalosa resticularia, Osteomugil persuii and Pomadasys kaakan, were less than 0.5. Investigating the diversity indices in the Hara protected area indicates the biological richness of this area, so that the lowest Margalf index was 42.5 at station 5 and the highest was 9.96 at station 1. The results of the Shannon index showed that station 2 had the lowest with 1.71 and station 1 with the highest score of 3.05. The Simpson index, except at station 2, equal to 0.54, was higher than 0.8 in other stations. The lowest Pilou index was 0.4 at station is 2 and the highest at station 3 with 0.73. The assemblage of fishes follows the clumped pattern distribution. The ABC curve and the W-Statistic index measured in the survey area indicate a desirable situation and the none-stress conditions in the Hara protected area.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Population dynamics ; Species diversity ; Distribution ; Fish ; Protected area ; Ilisha melastoma ; Gerres oyena ; Nematalosa nasus ; Liza klunzingeri ; Osteomugil perusii ; Sillago sihama ; Survey ; Community structure
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 80pp.
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  • 8
    facet.materialart.
    Unknown
    In:  http://aquaticcommons.org/id/eprint/21872 | 18721 | 2018-01-15 08:49:51 | 21872 | Iranian Fisheries Science Research Institute
    Publication Date: 2021-07-03
    Description: Population parameters of Whipfin silver-biddy (Gerres filamentosus) and Longtail silverbiddy (Gerres longirostris) were studied from January to December 2006 in three creeks (Markazi, Khalasi and Gabrik) of Hara protected area in Jask, Oman Sea. All fishes were sampled by boat trawl and beach seine. Growth parameters were determined using the monthly length–frequency parameters. The Mean total length was calculated at 6.2 and 5.4cm for Whipfin silver-biddy and Longtail silver-biddy. The values of L∞ and K for Whipfin silver-biddy were 16.8cm and 0.99 yr-1 and for Longtail silver-biddy, these were 15cm and 0.77 yr-1, respectively. The value of to was calculated at -0.12 year for both species. The longevity was estimated to be 3 years for Whipfin silver-biddy and 3.8 years for Longtail silver-biddy. The length-weight relationship were determined as W= 0.0088 L3.21 and W= 0.0087L 3.18 for Whipfin silver-biddy and Longtail silver-biddy, respectively. Results showed the fish were in their juvenile stage which emphasized the supporting roles of creeks for Gerridae as nursery ground.
    Keywords: Biology ; Environment ; Fisheries ; Stock assessment ; Population dynamic ; Gerridae ; Oman Sea ; iran ; Gerres filamentosus ; Gerres longirostris ; Jask ; Growth ; parameters
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 139-150
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