1,317 research outputs found
Internal stress affecting environmental fatigue of 7075-T651 alloy
Load history has been known to affect fracture and stress corrosion behavior. The degree to which it affects depends on the severity of the load history. It is known that shop peening can retard the SCC lives markedly in steels. Similarly, prestraining can reduce the KIscc and plateau velocity in high strength steels.
These types of experiments are difficult to quantify their effects on the SCC behavior. One can analyze the prestarining effects in a better way by analyzing the effects of single overloads followed by constant applied load to study the behavior. Such experiments can be done by observing the ‘incubation time’ for a crack to initiate in a fatigue pre-cracked sample, at various constant applied loads in a chemical environment. Such experiments have been conducted on a 7075 aluminum alloy for both static and cyclic loads. It is observed that results are similar in behavior. The data indicates the overall behavior can be analyzed by suggesting that the total stress at the crack tip is related to the contributions from chemistry of the environment and an additional factor from “internal stress” that comes from pre-strain. Hence, we can describe the crack initiation & growth criteria in terms of:
KIscc = Kapplied + Kinternal stress + Kenvironment \u3e Kthreshold
Such trends in the behavior, has been observed in pre-strained steel alloys prior to environmental exposure. The general behavior suggests that the internal stress affects the threshold KIscc more than the plateau velocity. The general SCC behavior is affected by both chemistry and internal stress under external static or cyclic loads
Biochemical investigations on vigour enhancement in aged seeds upon seed priming in onion
Loss in seed quality that occurs during all process, from maturation in the field to storage, leads to seed deterioration. Storage of onion seeds under ambient, hot and humid conditions is very problematic since these conditions deteriorate seed quality faster. Seed deterioration is associated with many metabolic defects that occur due to changes in enzymes and protein levels. This deterioration can be rectified to the extent possible by the technique of seed priming. The results clearly indicated that priming will restore the lost seed vigour in aged seeds due to reactivation of enzyme activity in old seeds. The germination percentage improved from 60% to 79.5% and 72.5% in GA3 and hydroprimed, respectively. Priming will also restore the lost seed vigour in aged seeds due to reactivation of proteins in old seeds and expression of these proteins in priming treatments are related to priming induced proteins in contrast to their absence in the aged seeds which are necessary for germination and longevity of seeds
Proapoptotic, anti-cell proliferative, anti-inflammatory and antiangiogenic potential of carnosic acid during 7,12 dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis
ERRATUMRajasekaran et al., Afr., J. Tradit Complement Altern Med. 2013; 10(1): 102–112Published online 2012 Oct 1.doi: 10.4314/ajtcam.v10i1.1
Concurrency and Communication: Lessons from the SHIM Project
Describing parallel hardware and software is difficult, especially in an embedded setting. Five years ago, we started the shim project to address this challenge by developing a programming language for hardware/software systems. The resulting language describes asynchronously running processes that has the useful property of scheduling-independence: the i/o of a shim program is not affected by any scheduling choices. This paper presents a history of the shim project with a focus on the key things we have learned along the way
Evaluation of suitable sites for mud crab farming in Ratnagiri District of Maharashtra, India
The State of Maharashtra has vast stretches of estuaries, creeks and
mangrove swamps, which offers great potential for aquaculture,
particularly for mud crab farming. In view of the natural resources and
market potential for mud crab, the Department of Forests, Government of
Maharashtra plans to promote mud crab farming through a novel
approach, which aims at providing livelihood support to the local
communities utilizing the mangrove wetlands; thereby the local
communities also shoulder the responsibility of conservation of mangroves.
In this backdrop, a study was conducted to identify the suitable sites for
sustainable mud crab culture, in GIS environment, based on various
physical and environmental criteria including topography, soil types, landuse
systems, vegetation, water quality, water availability, salinity, risks of
flooding, infrastructure, seed resources and availability, market and
support services. The brackishwater stretches of Anjarle, Kelshi, Aade,
Velas and Ansure in the Ratnagiri district of Maharashtra were studied,
and all study stations had patchy to thick mangrove vegetation. The major
mangrove species encountered were: Avicennia marina, Avicennia
officinalis, Sonneratia caseolaris, Rhizophora mucronata and Acanthus
ilicifolius. The pH of water was near-neutral to alkaline, whereas dissolved
oxygen levels were found to be within the ideal range. The salinity of the
tidal creeks ranged from 7.24 ppt (Velas) to 35.9 ppt (Ansure) which
generally varies with the tide. The ammonia levels which ranged from 0
(Aade and Ansure) to 0.5 ppm (Kelshi), falls within the safe levels for
Available online at: www.mbai.org.in doi: 10.6024/jmbai.2017.59.2.2014-05
aquaculture. The sediment pH ranged from 6.2 to 8.32. The organic
carbon levels in sediment ranged from 0.27 to 2.94% indicating medium
to high productive nature of sediment. Samples of mud crab collected from
the study areas were processed for screening for WSSV infection. All
samples gave Negative results in primary as well as nested PCRs,
indicating the absence of WSSV in the wild mud crab population.
Integrating the analysis result along with supporting spatial data with the
aid of GIS and Remote Sensing techniques, a total of 10.063 ha have been
evaluated as suitable areas for mud crab farming along the brackishwater
stretches of Anjarle (1.91 ha), Aade (2.069 ha), Kelshi (1.77 ha), Velas
(0.538 ha) and Ansure (3.776 ha)
Symmetries of supergravity black holes
We investigate Killing tensors for various black hole solutions of
supergravity theories. Rotating black holes of an ungauged theory, toroidally
compactified heterotic supergravity, with NUT parameters and two U(1) gauge
fields are constructed. If both charges are set equal, then the solutions
simplify, and then there are concise expressions for rank-2 conformal
Killing-Stackel tensors. These are induced by rank-2 Killing-Stackel tensors of
a conformally related metric that possesses a separability structure. We
directly verify the separation of the Hamilton-Jacobi equation on this
conformally related metric, and of the null Hamilton-Jacobi and massless
Klein-Gordon equations on the "physical" metric. Similar results are found for
more general solutions; we mainly focus on those with certain charge
combinations equal in gauged supergravity, but also consider some other
solutions.Comment: 36 pages; v2: minor changes; v3: slightly shorte
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