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Journal articles on the topic "Best weed strains"
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Gajić-Umiljendić, Jelena, Marija Sarić-Krsmanović, Ljiljana Radivojević, and Ljiljana Šantrić. "Allelopathic potential of actinobacteria for weed control." Biljni lekar 50, no. 2 (2022): 118–26. http://dx.doi.org/10.5937/biljlek2202118g.
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In laboratory conditions 10 actinobacteria strains were screened for germination and seedling growth of maize and Johnson grass. Primary inoculum of actiobacteria were grown in starch casein broth for 7 days in a shaking incubator. Ten seeds from both species, were placed inside sterile Petri dishes and moinsted with 5ml of the culture filtrate of actinobacteria and incubated at 26°C. After the period of 7 days, the percentage of germination was calculated and coleoptile and radicle length were measured. Suspensions of all 10 actinobacteria strains had an effect on seed germination and early seedling growth of maize and Johnson grass. The A18 strain proved to be the best candidate for further testing because the inhibitions for maize were less than 35% and for Johnson grass they were higher than 90%.
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Poonkodi, Kathirvel, and Subban Ravi. "Phytochemical investigation and in vitro antimicrobial activity of Richardia scabra." Bangladesh Journal of Pharmacology 11, no. 2 (March 19, 2016): 248. http://dx.doi.org/10.3329/bjp.v11i2.24666.
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<p class="Abstract">The present study was aimed to evaluate the phytochemical screening and antimicrobial activity of the petroleum ether and methanol extracts from the mature leaves of <em>Richardia scabra</em> from India. Disc diffusion method was used to determine the zone inhibition of the tested samples for antibacterial and agar plug method was used to determine the antifungal activity, while the microtube-dilution technique was used to determine the minimum inhibitory concentration. Both extracts showed significant antibacterial and antifungal activities when tested against 10 bacterial and four fungal strains. The minimum inhibitory concentrations of the methanol extract of<em> R. scabra</em> ranged between 12.5–100 μg/mL for bacterial strains. Alkaloids, steroids, flavonoids, fatty acids, terpenoids and simple sugar were detected as phytoconstituents of extracts. To the best of our knowledge, this is the first report against antimicrobial activity of common weed species <em>R. scabra</em> found in India.</p><p> </p>
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López, Ernesto, Enrique Becerra, Arturo Durán, Octavio Cano, Guillermo Fraire, Valentín Esqueda, and Dora Ortega. "Logros obtenidos en la investigación sobre el cultivo del frijol del proyecto CONACYT-TIPP-FRUOL en el sureste de México." Agronomía Mesoamericana 9, no. 2 (May 30, 2016): 131. http://dx.doi.org/10.15517/am.v9i2.20118.
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A project supported by the National Council of Science and Technology was carried out in Southeast Mexico between 1991 and 1993. The project's goal was to generate new technologies for bean crops. Results can be summarized as follows: (a) three inbred varieties were released (Negro Cotaxtla- 91, Negro Inifap and Negro Tacana) for the states of Veracruz, Chiapas, and for the Southeast region respectively; (b) foliar fertilization (Urea concentrated at 1.75%) as an agronomic technology was applied; (c) the best Rhizobium strains for the bean varieties in the state of Veracruz were found; (d) mechanical and chemical control for the main weed species was implemented; (e) main diseases and their distribution and control practices were also implemented; (f) the technological quality of the new varieties and their performance under different storage conditions was determined; and, (g) a program to train farmers was implemented in order to increase use of new varieties.
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Abdullahi, Wajiha M., Mahamadi Dianda, Ousmane Boukar, Ibnou Dieng, Gaya S. Mohammed, Nouhoun Belko, Abou Togola, et al. "Integrated management of Striga gesnerioides in cowpea using resistant varieties, improved crop nutrition and rhizobium inoculants." Plant and Soil 473, no. 1-2 (January 19, 2022): 197–213. http://dx.doi.org/10.1007/s11104-022-05295-7.
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Abstract Background Cowpea is a grain legume of major importance in sub-Saharan Africa where it is cultivated by smallholder farmers on poor soils and production is often constrained by the parasitic weed Striga gesnerioides. Method Experiments were conducted to assess the potential of rhizobium inoculation to mitigate Striga infection and increase cowpea productivity. We infested soils with S. gesnerioides and assessed the impact of treatments combining cowpea genotypes and bradyrhizobium inoculation on Striga dynamics and cowpea yield. In total, 20 cowpea genotypes were included, of which nine were resistant to Striga and 11 were susceptible. In the first experiment these were factorially combined with three inoculation options (two bradyrhizobium strains USDA3384 and IRJ2180A, and uninoculated control) in a screen-house using potted sterile soils. Second, the same trial was repeated in the field with basal phosphorus applied at sowing and a fourth treatment of fertilizer-N (urea) included testing whether N was limiting cowpea growth. The field trial also included a separate treatment with no input that served as a negative check. Result Significant genotype x treatment interactions were observed in nodule counts, Striga attachment, emergence, and cowpea shoot growth in the screen-house. There were few nodules across all cowpea lines. Striga counts were the lowest for resistant varieties with no emerged plants. Rhizobial inoculants depressed Striga counts with consistent differences across cowpea genotypes. Inoculation with IRJ2180A performed the best against Striga attachment in resistant genotypes, and against Striga emergence in susceptible genotypes. In the field trial, cowpea grown without inputs had the least number of nodules. The genotype x treatment interaction was significant: resistant cowpea genotypes were free of emerged Striga while there was much more Striga emergence without input addition with susceptible genotypes. A significant genotype x treatment interaction was observed on cowpea grain yield. Yield response to inoculation was clearest with resistant genotypes inoculated with the strain IRJ2180A. Conclusion The integrated use of Striga-resistant cowpea lines, basal phosphorus fertilizer and elite bradyrhizobium inoculants is a promising approach to mitigate Striga infection and increase cowpea productivity.
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West, R. J., and T. C. Vrain. "NEMATODE CONTROL OF BLACK ARMY CUTWORM (LEPIDOPTERA: NOCTUIDAE) UNDER LABORATORY AND FIELD CONDITIONS." Canadian Entomologist 129, no. 2 (April 1997): 229–39. http://dx.doi.org/10.4039/ent129229-2.
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AbstractFour steinernematid strains, Steinernema carpocapsae All strain, S. carpocapsae Umeå strain, S. feltiae Lie strain, and S. feltiae strain 27, were evaluated in laboratory and field tests as potential agents for the control of the black army cutworm, Actebia fennica (Tauscher). Although each of the six instars was susceptible to attack, incidences of infection were highest and generally over 60% for the third, fourth, and fifth instars when exposed to 100 infective juvenile nematodes in petri dishes. Fifth-instar larvae exposed for 1 week to soil containing 4000 infective juveniles in a 1:1:1 mixture of the L1c, All, and Umeå strains were most frequently infected with the L1c strain when reared at 10 and 12 °C and with the All strain when reared at 14 and 16 °C. One hundred thousand infective juveniles of the L1c, All, and Umeå strains and strain 27, alone and in various combinations, and applied by either a spray or soil-plug inoculation, killed black army cutworm larvae caged in the field for 1 week with treated black spruce seedlings and provided protection of current and 1 -year-old foliage. Treatments that included strain 27 provided the best protection when daily mean soil temperatures were 7–11 °C in comparison to treatments that included the Umeå or All strains, whereas treatments that included the All strain as a component appeared to be more effective than treatments containing the L1c and Umeå strains when daily mean soil temperatures were 16–17 °C.
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Jabir, Brahim, Noureddine Falih, Asmaa Sarih, and Adil Tannouche. "A Strategic Analytics Using Convolutional Neural Networks for Weed Identification in Sugar Beet Fields." Agris on-line Papers in Economics and Informatics 13, no. 1 (March 30, 2021): 49–57. http://dx.doi.org/10.7160/aol.2021.130104.
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Researchers in precision agriculture regularly use deep learning that will help growers and farmers control and monitor crops during the growing season; these tools help to extract meaningful information from large-scale aerial images received from the field using several techniques in order to create a strategic analytics for making a decision. The information result of the operation could be exploited for many reasons, such as sub-plot specific weed control. Our focus in this paper is on weed identification and control in sugar beet fields, particularly the creation and optimization of a Convolutional Neural Networks model and train it according to our data set to predict and identify the most popular weed strains in the region of Beni Mellal, Morocco. All that could help select herbicides that work on the identified weeds, we explore the way of transfer learning approach to design the networks, and the famous library Tensorflow for deep learning models, and Keras which is a high-level API built on Tensorflow.
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Nielsen, Tommy Harder, and Jan Sørensen. "Production of Cyclic Lipopeptides by Pseudomonas fluorescens Strains in Bulk Soil and in the Sugar Beet Rhizosphere." Applied and Environmental Microbiology 69, no. 2 (February 2003): 861–68. http://dx.doi.org/10.1128/aem.69.2.861-868.2003.
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ABSTRACT The production of cyclic lipopeptides (CLPs) with antifungal and biosurfactant properties by Pseudomonas fluorescens strains was investigated in bulk soil and in the sugar beet rhizosphere. Purified CLPs (viscosinamide, tensin, and amphisin) were first shown to remain highly stable and extractable (90%) when applied (ca. 5 μg g−1) to sterile soil, whereas all three compounds were degraded over 1 to 3 weeks in nonsterile soil. When a whole-cell inoculum of P. fluorescens strain DR54 containing a cell-bound pool of viscosinamide was added to the nonsterile soil, declining CLP concentrations were observed over a week. By comparison, addition of the strains 96.578 and DSS73 without cell-bound CLP pools did not result in detectable tensin or amphisin in the soil. In contrast, when sugar beet seeds were coated with the CLP-producing strains and subsequently germinated in nonsterile soil, strain DR54 maintained a high and constant viscosinamide level in the young rhizosphere for ∼2 days while strains 96.578 and DSS73 exhibited significant production (net accumulation) of tensin or amphisin, reaching a maximum level after 2 days. All three CLPs remained detectable for several days in the rhizosphere. Subsequent tests of five other CLP-producing P. fluorescens strains also demonstrated significant production in the young rhizosphere. The results thus provide evidence that production of different CLPs is a common trait among many P. fluorescens strains in the soil environment, and further, that the production is taking place only in specific habitats like the rhizosphere of germinating sugar beet seeds rather than in the bulk soil.
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Basnet, Ramesh, Anping Du, Li Tan, Ling Guo, Yanglin Jin, Zhuolin Yi, Tianfang Huang, Yang Fang, and Hai Zhao. "Investigation on Selection, Improvement of Biomass Production and Protein Content in Duckweeds (Lemna Strains)." Chiang Mai Journal of Science 51, no. 4 (July 31, 2024): 1–12. http://dx.doi.org/10.12982/cmjs.2024.065.
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Duc kweeds are becoming an emerging plant protein source as it may be produced in a more efficient and eco-friendly manner than other major crops. Screening is essential for tapping the desired traits. We conducted the screening on 32 Lemna species and accessions available in the Gene Bank. It follows two steps screening, primary screening involved culturing in 1/5 strength Hoagland Solution (HS) for one week. Based on protein %, the best three strains were cultured two sets ammonium and nitrate nitrogen source. Based on both biomass and protein content, D0158 strain was identified as the best. Then, the strain was optimized in five different parameters. In our study, we found that a longer photoperiod resulted in greater biomass accumulation and a lower percentage of protein. There was a 6.51% increase in crude protein, rising from 30.97% to 33.13% and dry biomass growth rate increase of 54.48% from 4.35 to 6.72 g/m2/d. The findings can be used to enhance the duckweed indoor cultivation system. Additionally, this protocol can be applied to other duckweed strains for similar purposes.
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Vázquez, María Belén, Viviana Barrera, and Virginia Bianchinotti. "Molecular identification of three isolates of Trichoderma harzianum isolated from agricultural soils in Argentina, and their abilities to detoxify in vitro metsulfuron methyl." Botany 93, no. 11 (November 2015): 793–800. http://dx.doi.org/10.1139/cjb-2015-0085.
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Metsulfuron methyl (MM) is a sulfonylurea herbicide used worldwide for the control of weeds in cereal crops. In a previous study, three Trichoderma strains (T5, T6, and T7) capable of using MM as a sole carbon and energy source were isolated. In this study, the three strains were identified as Trichoderma harzianum using genetic markers, and the transformation of MM by the T. harzianum strains was quantified using spectrophotometry. Solutions of different phytotoxic doses of MM were incubated with plugs of mycelia of the Trichoderma strains and the resulting mixtures were used to assess MM detoxification. The toxicity of the degradation products was tested with a bioassay using pre-germinated seeds of Lens culinaris Medik. and mycelia. Strain T7 was more efficient in transforming MM at higher concentrations than the T5 and T6 strains. In the bioassay, T5 showed the best performance at higher MM doses. We conclude that both T5 and T7 strains are promising for further studies regarding treatment or amelioration of MM contaminated soils.
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Nosike, R. J., D. N. Onunkwo, E. N. Obasi, W. Amaduruonye, H. O. Ukwu, O. F. Nwakpu, J. C. Ezike, and E. I. Chijioke. "Prediction of body weight with morphometric traits in some broiler chicken strains." Nigerian Journal of Animal Production 44, no. 3 (January 2, 2021): 15–22. http://dx.doi.org/10.51791/njap.v44i3.732.
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Morphometric traits also called linear body measurements or conformation traits are important parameters in predicting body weight especially in commercial breeders and producers. Thus, the study was carried out to predict body weight of broiler using linear body measurement. In this study, a total of 270 day old broiler chicks comprising of 90 chicks each of Abor Acre, Ross and Marshal Strains were used. Data were collected on body weight using body measurements to include breast length (BRL), thigh width (TW), shank length (SL), keel length (KL), wing length and drumstick length (DL). The regression analysis was simple linear regression. The values of the coefficient of determination (R2) in Abor Acre, Ross and Marshall strains ranged from 89.8 – 99.8; 88.4 – 98.9; and 80.8 – 99.5 respectively with thigh width showing the highest % R2 value of 99.8% in week 2; 66.5 – 97.9; 60.3 – 80.4 and 28.6 – 72.3 respectively with breast length (97.9%) having the highest % R2 value. This showed that breast length was the best predictor of the body weight of the broiler in week 4; 38.5 – 100; 88.0 – 98.6; 17.0 – 94.8 with shank length (100%) showing a 100% R2 value. This showed that breast length was the best predictor of the body weight of the broiler in week 4; 38.5 – 100; 88.0 – 98.6; 17.0 – 94.8 with shank length (100%) showing a 100% R2 value in week 6; 76.9 – 96.3, 72.2 – 88.8 and 58.1 – 97.6 respectively with wing length recording the highest % R2 value in week 6; 76.9 – 96.3, 72.2 – 88.8 and 58.1 – 97.6 respectively with wing length recording the highest value (97.9%) week 8. The different strains had different coefficient of determination (R2) values above 50% with different linear body parameter at different ages of the birds, indicating that any of the linear body parameter could be used to predict body weight of broiler chicken although, accuracy of prediction increased with increasing R2 value. Amongst all the linear body parameters evaluated, the shank length of Abor Acres strain had highest R2 value (100%) in week 6. Thus shank length was the best linear body parameter with 100% accuracy of prediction, and may be useful criterion in estimation of growth and prediction of body weight.
Books on the topic "Best weed strains"
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Exploring a World of Flavor: A Dive into the Array of Edibles and Hash Available for Online Purchase. calikushweb, 2024.
Find full textBook chapters on the topic "Best weed strains"
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Bauer, Mark S. "Ernest Dowson (1867–1900)." In A Mind Apart, 183–84. Oxford University PressNew York, NY, 2008. http://dx.doi.org/10.1093/oso/9780195336405.003.0061.
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Abstract To One in Bedlam With delicate, mad hands, behind his sordid bars, Surely he hath his posies, which they tear and twine; Those scentless wisps of straw, that miserably line His strait, caged universe, whereat the dull world stares, Pedant and pitiful. O, how his rapt gaze wars With their stupidity! Know they what dreams divine Lift his long, laughing reveries like enchanted wine, And make his melancholy germane to the stars? O lamentable brother! if those pity thee, Am I not fain of all thy lone eyes promise me; Half a fool’s kingdom, far from men who sow and reap, All their days, vanity? Better than mortal flowers, Thy moon-kissed roses seem: better than love or sleep, The star-crowned solitude of thine oblivious hours! Spleen I was not sorrowful, I could not weep, And all my memories were put to sleep. I watched the river grow more white and strange, All day till evening I watched it change. All day till evening I watched the rain Beat wearily upon the window pane
Conference papers on the topic "Best weed strains"
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Hertelé, Stijn, Wim De Waele, Rudi Denys, Matthias Verstraete, Koen Van Minnebruggen, and Anthony Horn. "Weld Strength Mismatch in Strain Based Flaw Assessment: Which Definition to Use?" In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78306.
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Weld strength mismatch is a key factor in the strain based assessment of flawed girth welds under tension. A strength overmatching weld shields potential flaws within the weld itself from remotely applied deformations and consequently reduces crack driving force. Although this effect has been recognized for decades, different weld strength overmatch definitions exist and it is not yet fully established which of those is most relevant to a strain based flaw assessment. In an effort to clarify this unsolved question, the authors have performed a large series of parametric finite element analyses of curved wide plate tests. This paper provides an experimental validation of the model and subsequently discusses representative results. It is found that crack driving force is influenced by the shape of the pipe metals’ stress-strain curves, which influences the representativeness of two common mismatch definitions (based on yield strength and on ultimate tensile strength). It can be concluded from further observations that effects of strength mismatch on strain capacity of a flawed girth weld are best described on the basis of a flow stress, defined as the average of yield and ultimate tensile strength. Based on the observations, a framework for a new strain capacity equation is proposed.
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Wang, Yong-Yi, David Horsley, and Steve Rapp. "Evolution of Linepipe Manufacturing and its Implications on Weld Properties and Pipeline Service." In 2016 11th International Pipeline Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ipc2016-64632.
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Pipe grade is a dominant parameter in a pipeline’s service life. Critical decisions on the design, construction, and maintenance of pipelines are made on the basis of pipe grade. The implied assumptions or expectations are that pipes of the same grade would behave similarly and the experiences with a particular grade can be applied to all pipelines of the same grade. This simplification does not adequately take into account the other characteristics that are not represented by pipe grade, but can play a critical role in the safe and economical operation of pipelines. For instance, the evolution of steel-making processes and advancements in field welding practice can lead to significant differences in weld behavior among pipes of the same nominal grade. Most of the design, construction, and maintenance practices in the pipeline industry were established before the extensive use of modern control-rolled and microalloyed steels. With the exception of a few isolated research projects, the impacts of the fundamental changes in the steel metallurgy in modern microalloyed steels have not been systematically examined and understood. For instance, these steels may have very low strain-hardening capacity as a result of the TMCP process and may be subject to high levels of heat-affected zone (HAZ) softening due to their ultra-low carbon low-hardenability steel chemistry. HAZ softening reduces the longitudinal pipe strain capacity of girth welds, and low strain-hardening can potentially have a negative impact on tolerance to anomalies such as corrosion or mechanical damage. This paper starts with a brief review of linepipe manufacturing history with a focus on the chemical composition and rolling practices that directly affect the mechanical properties and the response to welding thermal cycles. The characteristics of linepipes made from modern microalloyed steels are contrasted with those made from vintage hot-rolled and normalized steels. The resulting mechanical properties of these two types of materials in the presence of welding thermal cycles are presented, and compared in terms of their behavior. The consequence of the weld characteristics is shown using examples of girth welds subjected to longitudinal strains. The implications of the pipe and weld characteristics on the design, field girth welding, and maintenance of pipelines are highlighted. Future directions and best practices in linepipe alloying and manufacturing strategies, linepipe specifications, field girth welding, and building strain-resistance girth welds are briefly described. It is emphasized that assessing the performance of pipelines based on their grades has fundamental shortfalls, and that gaps in codes and standards can lead to unexpected outcomes in pipeline integrity. In the long-run, revising relevant codes and standards is necessary to ensure consistent and reliable applications of new materials in the entire industry.
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Herter, Karl-Heinz, Xaver Schuler, Michael Hoffmann, and Peter Kopp. "Fatigue Behavior of Dissimilar Welds Used for Nuclear Piping." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97400.
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Due to specific requirements in NPP piping different materials are used and connected by dissimilar welds (DM). The fatigue behavior of such welds must be known for design and safety evaluations. The overall fatigue behavior of welds depends on the properties of the different weld sections and their interaction. The welding may influence the fatigue behavior of the base materials in the vicinity of the weld. The investigation deals with the fatigue behavior of DM typical for German NPP: ferritic steel 20MnMoNi5-5 welded to austenitic steel X6CrNiNb18-10 using nickel based alloy for buttering. Fatigue specimens were taken from each region of the weld (ferritic steel near weld, buttering, connection weld, austenitic steel near weld). Additionally specimens were taken containing two adjacent material regions and the respective fusion line. For each position specimens were tested in fully reversed strain controlled conditions at room temperature and total strain amplitude of 0.25%. The results were compared with the best-fit curves for austenitic and ferritic steels.
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Liu, Ming, Yong-Yi Wang, David Horsley, and Steve Nanney. "Multi-Tier Tensile Strain Models for Strain-Based Design: Part 3 — Model Evaluation Against Experimental Data." In 2012 9th International Pipeline Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ipc2012-90660.
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This is the third paper in a three-paper series related to the development of tensile strain models. The fundamental basis [1] and formulation [2] of the models are presented in two companion papers. This paper covers the evaluation of the models against large-scale experimental data which include a total of 24 full-scale pipe tests with and without internal pressure [3,4] and 30 curved wide plate (CWP) tests [5,6]. The 24 full-scale pipe specimens are nominally X65 grade (12.75″ OD and 12.7-mm wall thickness) and made by two manufacturers. The actual yield strength of the two pipes differs by approximately 14 ksi. The girth welds are made with three welding procedures, creating three weld strength levels. The full-scale test program are designed to evaluate the effects of internal pressure, weld strength mismatch, pipe strength, pipe Y/T ratio, flaw location, flaw size, and toughness. The 30 CWP specimens are from 36″ OD and 19.1 mm wall thickness X100 pipes. The girth welds are made with two welding procedures, creating two slightly different weld strength mismatch levels. The CWP test specimens expand the range of material grade and wall thickness for the model evaluation. The model evaluation demonstrates that the overall correlations between the experimental test data and model predations are similar when the model predictions are made with Level 2 and 3 procedures and various toughness options. The Level 2 procedure with Charpy energy option and Level 3b provide the best overall one-to-one correlation between the test data and model prediction. The Level 3b shows greater scatter than Level 2 with the Charpy energy option. The most significant contributor to the TSC variations and the difference between the measured and predicted TSCs is the strength variation in the pipes. A small variation in the strength can lead to a large variation of the measured remote strain even when the flaw behavior is essentially the same. For the 24 full-scale pipe tests, a strength variation of 1 ksi in the pipes would explain the large variations of the measured TSC in comparison to the model predictions. The TSC models produce consistent results that capture the overall trend of the test data.
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Chell, Graham, Stephen J. Hudak, and Yi-Der Lee. "Full-Scale Validation of a Flaw Assessment Methodology for Welded and Reeled Pipes." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-80210.
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Pre-existing weld flaws in pipes subjected to high strains resulting from reeling installation may extend by combined ductile tearing and low-cycle fatigue (LCF). The increase in flaw sizes from this process will reduce the flaw tolerances of reeled pipes subjected to subsequent service high-cycle fatigue (HCF) exposure compared to the tolerances determined ignoring the reeling process. This paper describes a flaw assessment methodology that includes the synergy between ductile tearing and LCF flaw growth due to reeling. The methodology utilizes the Level 3C (J-based) failure assessment diagram (FAD) approach of BS 7910 to explicitly account for the effects of flaw and pipe geometries, as well as material stress-strain behavior, on the crack tip driving force, J. The Level 3C FADs used herein are derived from and validated against the results of a matrix of J-based finite element analyses (FEA) of pipes. They have been incorporated into the computer program FlawPRO™ developed for the offshore industry that enables a comprehensive engineering critical assessment (ECA) for flawed reeled pipes to be performed. The methodology incorporated into FlawPRO is validated against the results of full-scale tests on reeled pipes containing weld flaws subjected to a variety of reeling scenarios. The validation includes investigations into the effects on predicted flaw growth of using J-resistance curves measured on SENB and SENT specimens and of assuming strain versus load controlled reeling. The best agreement with the flaw extensions measured in the full-scale tests is obtained when an SENT J-R curve is used together with assuming reeling occurs under strain controlled conditions. It is concluded that the reeling methodology in FlawPRO is successfully validated by the full-scale test results.
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Smith, Michael C., Ann C. Smith, Robert C. Wimpory, Carsten Ohms, Brahim Nadri, and P. John Bouchard. "Optimising Residual Stress Measurements and Predictions in a Welded Benchmark Specimen: A Review of Phase 2 of the NeT Task Group 1 Single Bead on Plate Round Robin." In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77157.
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A single weld bead deposited on a flat plate is a deceptively simple problem that is in practice a challenge for both measurement and prediction of weld residual stresses. Task Group 1 of the NeT collaborative network has examined this problem in a two-phase programme extending from 2002 to 2008. Ten independent sets of residual stress measurements have been reported using diverse techniques, and over forty finite element simulations have been performed. This paper reviews Phase 2 of the Task Group 1 round robin. Here, the finite element simulations all made use of optimised thermal solutions, in which the global welding parameters, including efficiency, were fixed, and only the detailed heat source geometry was varied. These resulted in accurate far field welding temperature distributions, with significant variability only close to the weld bead itself. The subsequent mechanical analyses made use of kinematic, isotropic, and mixed isotropic-kinematic material constitutive models, and made a variety of assumptions about the introduction of weld filler material to the structure and the handling of high temperature inelastic strains. The large database of measurements allowed the derivation of statistical best estimates using a Bayesian “duff data” approach, and these best estimates were compared with the predictions to establish the most accurate material constitutive models. The most accurate predictions of residual stress were made using non-linear kinematic or mixed isotropic-kinematic constitutive models. The methods used to handle high-temperature inelastic strains influenced the predicted stresses only in regions where very high temperatures were predicted during welding. The results emphasise the importance and value of both well-characterised benchmark problems and international collaboration in the development of technologies to both measure and predict weld residual stresses.
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Dabiri, Arman, and Edgar Madril. "Isothermal Creep Behavior of 3M™ Scotch-Weld™ EC-2216 B\A in Single Lap Joints." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-60376.
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This paper studies the isothermal creep behavior of the 3M™ Scotch-Weld™ EC-2216 B\A Gray (EC-2216) epoxy in single lap joints subjected to a uniaxial tensile load. The time-independent mechanical properties of EC-2216 such as the Young’s modulus, shear modulus, and bulk modulus have been reported in the literature, but the results are not consistent. However, to the best knowledge of the authors its shear stress-strain constitutive equation has not been obtained yet. Thus, in this paper, we propose the shear stress-strain constitutive equation of the EC-2216 in single lap joints subjected to uniaxial tensile tests at room temperature (24±3°C). First, a viscoelastic model is estimated in short-term experiments within the viscoelastic regime. Second, the creep deformation of the EC-2216 is modeled by different conventional imperial models. Third, different conventional creep rate models are used to estimate the steady state creep rate of the third stage, which mainly indicates the longevity of the material. Moreover, the failure accumulate strain is obtained based on the maximum strain criterion, for different shear stress levels. Finally, the proposed models are compared to the current published data.
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Barbaro, Frank, and Leigh Fletcher. "Undermatching and Low Strain In-Service Failures in X70 Line Pipe: Contributions From Standards, Specifications and Coating." In 2020 13th International Pipeline Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/ipc2020-9241.
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Abstract Some 10 incidents of low strain in-service and pre-service hydrotest failures in girth welds have been reported in North America since the Enterprise Products ethane pipeline failure in 2015. No such failures have been reported in Australia, despite the similarities in Standards, the line pipe data, and the use of manual SMAW using fully cellulosic procedures. There are however significant differences that warrant further investigation and adoption in terms of best practice to ensure the security and safety of our pipeline networks. Some unique differences and observations in terms of pipe properties, weld qualification procedures, test methods and even full scale pressure burst tests before and after coating are described to highlight subtle differences in the standards that may provide clarity in explaining pipeline girth weld failures and it is anticipated may also provide guidance for the future.
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Bourgeois, M., O. Ancelet, and S. Chapuliot. "Elasto-Plastic Properties in Dissimilar Metal Weld Junctions: Stress-Strain Curves Determination for Constitutive Materials." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45179.
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Within the framework of European project MULTIMETAL (Structural performance of multi-metal component), several fracture tests on different types of multi-material specimens have been performed. Present fracture toughness standard methods, e.g. ASTM E 1820 are not directly intended for Dissimilar Metal Weld (DMW). Therefore further investigations are needed in order to define the best practice in fracture mechanical tests and their analysis for DMWs. Specimens are taken from welded plates: a narrow gap Inconel DMW junction between ferritic and austenitic stainless steels, designed and delivered by AREVA France. The aim of this work is to provide guidelines for the determination of DMW fracture properties. For that purpose, fracture specimen needs to be modelled by FE. The first task, which is the purpose of that paper, is the determination of the mechanical properties in terms of stress-strain curve of all DMW constitutive materials: austenitic stainless steel, ferritic steel, heat affected zone of the ferritic steel zone and Nickel alloy zone properties. Conventional techniques for tensile test are not able to provide the tensile curve of the different materials constituting a weld joint. Image correlation techniques are well suitable but imply too long and difficult work for the images analysis. Therefore CEA has developed an intermediate solution based on laser sensors which provides a complete profile of the specimen during the tensile test. Using Bridgman equations, the stress and strain can be deduced from the measurement of the shape of the specimen (reduction of section but not only…). This innovative device has been used with new developments using local Bridgman equations in the post-processing of measurements. This allows to access to the material behaviour of several materials with only one specimen. Numerical interpretation using FE methods is presented and confirms the material behaviour determined from the experimental work using Bridgman equations assumptions. Finally, this combined experimental and numerical work has provided material data relative to all constitutive materials of the DMW junction. A hardened area in stainless steel material due to the welding process has been pointed out, and the heat affected zones of the ferritic material have been characterized in terms of stress-strain curves. The next stage of the project is to carry out tests on fracture specimens and to model these multi-materials specimens by FE. The gradient of elasto-plastic properties is now available for this next step.
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Asadi, Mahyar, and John A. Goldak. "A Direct-Search Computational Weld Mechanics Optimization Using Least-Square Approximation." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57960.
Full textAbstract:
Using a frame-work for exploring a design space in Computational Weld Mechanics (CWM), a recent direct-search algorithm from Kolda, Lewis and Torczon is modified to use a least-square approximation to improve the method of following a path to the minimum in the algorithm. To compare the original and modified algorithms, a CWM optimization problem on a 152 × 1220 × 12.5 mm bar of Aluminum 5052-H32 is solved to minimize the weld distortion mitigated by a side heating technique. The CWM optimization problem is to find the best point in the space of side heater design parameters: power, heated area, longitudinal and transverse distance from the weld such that the final distortion is as low as possible (minimized). This CWM optimization problem is constrained to keep the stress level generated by the side heaters, in the elastic region to avoid adding an additional permanent plastic strain to the bar. The number of iterations, size of DOE matrix required and CPU time to find the minimum for the two algorithms are compared.
Reports on the topic "Best weed strains"
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Shen, Gianetto, and Tyson. L52342 Development of Procedure for Low-Constraint Toughness Testing Using a Single-Specimen Technique. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), December 2011. http://dx.doi.org/10.55274/r0010687.
Full textAbstract:
Pipelines from remote frontier regions are increasingly required to have adequate resistance to large deformations such as that caused by ground movement. In response to this, �strain-based design"� has been developed to enable assessment of imperfections at applied strains beyond yield. In addition, it is proposed to take advantage of the increased apparent toughness of pipe under low constraint, such as girth weld imperfections under axial tension, compared with the high-constraint toughness measured in conventional tests such as ASTM E1290 [1]. Application of low-constraint testing has been dvantageously applied in assessment of toughness for offshore pipeline projects. Also in the pipeline industry, demands on new pipeline projects include low design temperatures as well as high strain capacity. At the same time, increased strength is specified, which increases the level of required toughness. These factors make it increasingly important to assure weldment toughness, in particular to ensure that the failure mode remains ductile. It is well known that brittle cleavage is especially sensitive to constraint, and the availability of a toughness test that would reproduce field conditions would enable more rational development and acceptance of candidate welds and, in particular, enable more appropriate testing of weld heat-affected zones. This work was performed for specific application to surface circumferential cracks in pipe under strain-based design, for which the best constraint matching has been found to occur for clamped single-edge tension (SE(T)) specimens with H/W=10. For this geometry, a test procedure similar to that of ASTM E1820-06 for single-edge bend (SE(B)) and compact tension (C(T)) specimens was developed for J-resistance tests using a single-specimen technique. All the equations used in the procedure, including those for evaluation of J-integrals from the area under load/plastic crack mouth opening displacement (CMOD) curves, and evaluation of crack length from unloading compliance including rotation correction, were developed using finite element analysis (FEA) with a range of crack depths, focusing on a/W= 0.2 to 0.5 which is of most practical interest. The present procedure is compared with that of E1820 for SE(B) testing regarding evaluation of J-integral with crack growth correction, crack length evaluation, and correction of compliance for rotation.
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Wideman, Jr., Robert F., Nicholas B. Anthony, Avigdor Cahaner, Alan Shlosberg, Michel Bellaiche, and William B. Roush. Integrated Approach to Evaluating Inherited Predictors of Resistance to Pulmonary Hypertension Syndrome (Ascites) in Fast Growing Broiler Chickens. United States Department of Agriculture, December 2000. http://dx.doi.org/10.32747/2000.7575287.bard.
Full textAbstract:
Background PHS (pulmonary hypertension syndrome, ascites syndrome) is a serious cause of loss in the broiler industry, and is a prime example of an undesirable side effect of successful genetic development that may be deleteriously manifested by factors in the environment of growing broilers. Basically, continuous and pinpointed selection for rapid growth in broilers has led to higher oxygen demand and consequently to more frequent manifestation of an inherent potential cardiopulmonary incapability to sufficiently oxygenate the arterial blood. The multifaceted causes and modifiers of PHS make research into finding solutions to the syndrome a complex and multi threaded challenge. This research used several directions to better understand the development of PHS and to probe possible means of achieving a goal of monitoring and increasing resistance to the syndrome. Research Objectives (1) To evaluate the growth dynamics of individuals within breeding stocks and their correlation with individual susceptibility or resistance to PHS; (2) To compile data on diagnostic indices found in this work to be predictive for PHS, during exposure to experimental protocols known to trigger PHS; (3) To conduct detailed physiological evaluations of cardiopulmonary function in broilers; (4) To compile data on growth dynamics and other diagnostic indices in existing lines selected for susceptibility or resistance to PHS; (5) To integrate growth dynamics and other diagnostic data within appropriate statistical procedures to provide geneticists with predictive indices that characterize resistance or susceptibility to PHS. Revisions In the first year, the US team acquired the costly Peckode weigh platform / individual bird I.D. system that was to provide the continuous (several times each day), automated weighing of birds, for a comprehensive monitoring of growth dynamics. However, data generated were found to be inaccurate and irreproducible, so making its use implausible. Henceforth, weighing was manual, this highly labor intensive work precluding some of the original objectives of using such a strategy of growth dynamics in selection procedures involving thousands of birds. Major conclusions, solutions, achievements 1. Healthy broilers were found to have greater oscillations in growth velocity and acceleration than PHS susceptible birds. This proved the scientific validity of our original hypothesis that such differences occur. 2. Growth rate in the first week is higher in PHS-susceptible than in PHS-resistant chicks. Artificial neural network accurately distinguished differences between the two groups based on growth patterns in this period. 3. In the US, the unilateral pulmonary occlusion technique was used in collaboration with a major broiler breeding company to create a commercial broiler line that is highly resistant to PHS induced by fast growth and low ambient temperatures. 4. In Israel, lines were obtained by genetic selection on PHS mortality after cold exposure in a dam-line population comprising of 85 sire families. The wide range of PHS incidence per family (0-50%), high heritability (about 0.6), and the results in cold challenged progeny, suggested a highly effective and relatively easy means for selection for PHS resistance 5. The best minimally-invasive diagnostic indices for prediction of PHS resistance were found to be oximetry, hematocrit values, heart rate and electrocardiographic (ECG) lead II waves. Some differences in results were found between the US and Israeli teams, probably reflecting genetic differences in the broiler strains used in the two countries. For instance the US team found the S wave amplitude to predict PHS susceptibility well, whereas the Israeli team found the P wave amplitude to be a better valid predictor. 6. Comprehensive physiological studies further increased knowledge on the development of PHS cardiopulmonary characteristics of pre-ascitic birds, pulmonary arterial wedge pressures, hypotension/kidney response, pulmonary hemodynamic responses to vasoactive mediators were all examined in depth. Implications, scientific and agricultural Substantial progress has been made in understanding the genetic and environmental factors involved in PHS, and their interaction. The two teams each successfully developed different selection programs, by surgical means and by divergent selection under cold challenge. Monitoring of the progress and success of the programs was done be using the in-depth estimations that this research engendered on the reliability and value of non-invasive predictive parameters. These findings helped corroborate the validity of practical means to improve PHT resistance by research-based programs of selection.