248 research outputs found
Reproductive morphology of Hoppea fastigiata C B Clarke
The reproductive morphology ofHoppea fastigiata has been studied and described. Evolutionary trends in the subtribe Erythraeinae are highlighted
Significance of Creep-Fatigue Interactions in Strctural Integrity Assessment
Creep-fatigue interaction is a special phenomena that have a detrimental effect on the performance of metal parts of components operating at elevated temperatures. This paper deals with the simultaneous interactions between creep and fatigue. The effect of hold time, hold position, temperature and creep ductility on creep-fatigue interaction life and damage modes of several high temperature alloys are presented in detail. The inherent deficiencies and potentially serious consequences of over-or under- design by using the classical Linear Time and Cycle-Fraction rule for predicting structural durability under high temperature creep-fatigue conditions are presented. The potential of a strain based approach in accurately predicting creep-fatigue life for ensuring
structural integrity is outlined
Principles of Contract Design
Economic contract theory postulates two obstacles to complete contracts: high transaction costs and high enforcement (or verification) costs. The literature has proposed how parties might solve these problems under a stylized litigation system, but it does not address the question of how parties design contracts under the existing adversarial system, that relies on the parties to establish relevant facts indirectly by the use of evidentiary proxies. We advance a theory of contract design in a world of costly litigation. We examine the efficiency of investment at the front-end and back-end of the contracting process, where we focus on litigation as the back-end stage. In deciding whether to express their obligations in specific or vague terms, contracting parties implicitly choose their allocation of costs between the front- and back-end. When the parties agree to vague terms (or standards), such as best efforts or commercial reasonableness, they delegate to the back-end the task of selecting proxies: e.g., the court selects market indicators that serve as benchmarks for performance. When the parties agree to specific terms(or rules), they invest more at the front-end to specify proxies in their contract and thereby leaving a smaller task for the enforcing court. In this Article, we explore the choice between rules and standards in terms of this tradeoff, and offer an explanation for why contracts in practice have a mix of vague and specific provisions. We then suggest that parties can achieve further contracting gains by varying procedural rules governing the prospective enforcement of their disputes. We illustrate by examining provisions in commercial contracts that allocate burdens and standards of proof. If the parties can improve the cost-effectiveness of litigation in this manner, they can reduce back-end costs. They thereby create opportunities to further lower contracting costs (or to improve the incentive gains from contracting) by shifting more investment to the back-end by increasing their use of vague terms. Vague terms have fallen into disfavor with contract theorists and this Article offers a justification for why they are nevertheless commonplace in commercial practice. Our analysis highlights the general and valuable lesson that the anticipated path of litigation is relevant to contract design
Sea erosion along the Andhra Pradesh coast
Andhra Pradesh with a coastline of around 974 km
has frequently been affected by cyclones and
inundated by storm surges. Sea erosion is noticed at
Visakhapatnam, Bhimunipatnam and in the East and
West Godavari districts. Vishakhapatnam coast is
facing erosion since long specially at Ramakrishna
Beach. In 2013 and 2014, the cyclones ‘Phailin’ and
‘Hudhud’ further hastened erosion of the Ramakrishna
Beach, severely damaging the adjacent protection
wall and road. Uppada village which is 22 kilometres
away from Kakinada also faces severe erosion. The
Kakinada-Uppada road is gradually disappearing due
to shoreline erosion
Baldev Raj (1947-2018)
Baldev Raj (BR), a distinguished scientist
and technologist of India passed
away on 6 January 2018 at Pune while he
was on official duty.
BR was born on 9 April 1947 in
Jammu. He lost his father at a very early
age. In 1969, he graduated with a gold
medal in the engineering discipline (metallurgy)
from Ravishankar University,
Raipur. In 1970, he joined the 14th batch
of Bhabha Atomic Research Centre
(BARC) Training School in Trombay.
After successful completion of training,
he joined BARC as a Scientific Officer.
BR obtained his Ph D from the Indian
Institute of Science (IISc), Bangalore in
1990 in the Faculty of Engineering, in a
multidisciplinary area encompassing collaboration
between the Department of
Metallurgy and Aerospace Engineering
Temperature and Strain-Rate Effects on Low-Cycle Fatigue Behavior of Alloy 800H
The effects of strain rate (4 x 10(exp -6) to 4 x 10(exp -3)/s) and temperature on the Low-Cycle Fatigue (LCF) behavior of alloy 800H have been evaluated in the range 750 C to 950 C. Total axial strain controlled LCF tests were conducted in air at a strain amplitude of +/- 0.30 pct. LCF life decreased with decreasing strain rate and increasing temperature. The cyclic stress response behavior showed a marked variation with temperature and strain rate. The time- and temperature- dependent processes which influence the cyclic stress response and life have been identified and their relative importance assessed. Dynamic strain aging, time-dependent deformation, precipitation of parallel platelets of M(23)C6 on grain boundaries and incoherent ledges of twins, and oxidation were found to operate depending on the test conditions. The largest effect on life was shown by oxidation processes
Effect of Processing Route on Strain Controlled Low Cycle Fatigue Behavior of Polycrystalline NiAl
The present investigation examines the effects of manufacturing process on the total axial strain controlled low cycle fatigue behavior of polycrystalline NiAl at 1000 K, a temperature above the monotonic Brittle-to-Ductile Transition Temperature (BDTT). The nickel aluminide samples were produced by three different processing routes: hot isostatic pressing of pre- alloyed powders, extrusion of prealloyed powders, and extrusion of vacuum induction melted ingots. The LCF behavior of the cast plus extruded material was also determined at room temperature (below the BD77) for comparison to the high temperature data. The cyclic stress response, cyclic stress-strain behavior, and strain-life relationships were influenced by the alloy preparation technique and the testing temperature. Detailed characterization of the LCF tested samples was conducted by optical and electron microscopy to determine the variations in fracture and deformation modes and to determine any microstructural changes that occurred during LCF testing. The dependence of LCF properties on processing route was rationalized on the basis of starting microstructure, brittle-to-ductile transition temperature, deformation induced changes in the basic microstructure, deformation substructure, and synergistic interaction between the damage modes
Appraisal of penaeid prawn fishery by large mechanized trawlers (Sona boats) off Visakhapatnam, SE coast of India
Surge in fishing effort and penaeid prawn catch was recorded during the study period with that of 2006-10. Decline in Catch per Hour (CPH) and penaeid prawn ratio (%) to total fish catch was observed. Penaeid prawns accounted for 15.5% of the sona boat landings. Annually, mean penaeid prawn landings were estimated at 6,184 t. Prawn catch excelled by M. monoceros (20.5%), S. crassicornis (13.7%) and M. barbata (7.8%)
Assessment of penaeid prawn fishery by small mechanized trawlers off Visakhapatnam, east coast of India
Study was conducted to assess penaeid prawn fishery by small mechanized trawlers along Visakhapatnam coast during 2011 to 2015. Penaeid prawn landings, fishing effort, CPH and species composition was collected from small mechanized trawlers. Expected penaeid prawn landings (t) were estimated by Schaefer production model (CEDA) based on fishing effort and penaeid prawn catch. Study discovered that there was considerable rise in fishing effort (h) (33.7%) and penaeid prawn landings (17.35%) during the study period with that of 2006-10. Drop in catch per hour (12.24%) and penaeid prawn proportion (12.39%) was registered. Mean fishing effort (h) per unit was registered as 115h and catch per hour of penaeid prawns ranged from 3.37 to 5.73 kgh-1. All in all, penaeid prawn landings accounted for 3,598 t annually and attributed to 14.8% of the total fish catch
Jellyfish as an export commodity
Recently, jellyfish blooms have been reported
with increased frequency from several parts of the
world and it has been suggested that this
phenomenon might be related to over-fishing and
other human activities that are driving marine
ecosystems off balance. It has contributed to the
formulation of the “fishing down the food chain”
hypothesis, which is based on the assumption that
the reduction in large species marine predator
populations is promoting the growth of organisms
from lower levels of the food chain. Rising sea
temperature is also considered as a reason for the
occurrence of jellyfish fishery
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