Study of tensile deformation behaviour of M250 grade maraging steel using acoustic emission

Tensile testing of solution annealed and thermally aged (755 K for various durations in the range of 0.25-100 h) specimens of M250 grade maraging steel has been carried out along with acoustic emission (AE) monitoring. Results have shown that strength increases and ductility decreases upon ageing up to 10 h and this has been attributed primarily to the precipitation of Ni3Ti. Continued increase in strength up to 40 h of ageing has been attributed primarily to the precipitation of Fe2Mo in addition to Ni3Ti. Increase in ductility for 10-40 h of ageing has been attributed to dissolution of needle like Ni3Ti precipitates and formation of fine spherical Fe2Mo. Ageing beyond 40 h decreases strength and increases ductility due to the reversion of martensite to austenite and coarsening of the precipitates. The AE generated during tensile deformation depends on the ageing time. Increased occurrence of shearing of the precipitates by dislocations and increased brittleness of the matrix up to 10 h ageing increases the AE. The decrease in the AE beyond 10 h of ageing is due to the occurrence of deformation by Orowan looping, dissolution of Ni3Ti precipitates and austenite reversion. The scanning electron microscopy (SEM) of the fracture surfaces has shown ductile fracture characterized by dimples and changes in the size and shape of the dimples with ageing time

A web GIS based study for managing mangroves of Krishna Delta, Andhra Pradesh, India

Mangroves are one among the most productive ecosystem which provide a wide range of services to the coastal people, which includes the provision of food and timber products and coastal defense services by reducing risk from coastal hazards. Several research found that mangrove forests have been degraded throughout the world since 80s onwards due to anthropogenic factors and India is no exception for the same. The current study was conducted in the Krishna’s wetland, which is located in Krishna district of Andhra Pradesh (AP), South India, India. The Mangroves of Krishna is second largest mangrove ecosystem in AP, fifth in East coast, eighth in India and it is rich in biodiversity but highly vulnerable because of anthropogenic and natural factors which makes this study area very scared. Information on Krishna mangroves and their geospatial information are owned by different institutions to build this geospatial dataset as open to access everyone. The WebGIS is a latest advancement and hybrid of GIS and Internet technologies for the dissemination of the geospatial datasets and its variations through the web. The main objective of the current study is to develop and demonstrate a WebGIS using open source software and integrate geospatial datasets of the mangroves of Krishna into WebGIS platform and to analyse and assess areas that are degraded by influenced parameters and in need of sustainable management.The result revealed that the area of mangroves in Krishna was decreased from 2,454 ha in 1990 to 1,363 ha in 2000 to 1,339 ha in 2011. On the other hand the areas of mangroves in the Krishna delta were increased to about 678 ha from 1990 to 2000 and 2,230 ha from 2000 to 2011. It may be pointed out that the variation in mangrove covers in the study area due to land use conversion for different purposes and mangroves provides coastal defense services by reduce risk of coastal hazards. It is may be concluded that this WebGIS study is very useful and unique because it is sharing data through internet to everyone as it save money, time and data duplication, which are needed to different stakeholders such as researchers, decision makers, planners for the sustainable management of mangrove ecosystem

Nano-Bio Aldehyde system for Leather Manufacture

Content: Development of eco-friendly chemicals from natural renewable resources are widely explored owing to its eco-acceptable and sustainability. Exploring biopolymers is the need of an hour to combat the sustainability in leather processing. Finishing is an imperative step that enhances the aesthetic appeal of the final leathers, in which, protein finishing system is known for its glazing properties. Commonly used cross-linkers as such formaldehyde and glutaraldehyde are restricted owing to biocompatibility issues. However, the use of crosslinker is inevitable for protein finish system. In the present research, nano-bio polyaldehyde (NBP) system is established through selective oxidation of starch; the size of the system is fine-tuned in the nano range for effective and efficient crosslinking through emulsion technique. The architectural design of NBP is ascertained as a good crosslinking agent for leather finishing chemicals from the characterization studies. A particle size of the NBP system found to be in the range of 80-110 nm. The surface properties of NBP treated leathers were characterized by the contact angle. The leather samples showed improved hydrophobicity nature with a contact angle of ~ 126º and also enhanced wet, rub fastness, color fastness, and adhesion strength. The study provides an insight on tunability of known biopolymers for developing sustainable technology. Take-Away: An insight on tunability of known biopolymers for developing sustainable technolog

Ultrasonic Examination of Thin Walled Stainless Steel Tubes by Synthetic Aperture Focusing Technique

The objective of Nondestructive Testing (NDT) is to detect flaws in the components, and characterize them by their size, shape, orientation etc. so that decision on fitness for service of the components can be made. In the case of thin walled tubes, ultrasonic or eddy current examination is generally performed for detection of defects. During the inspection of thin walled stainless steel tubes used in nuclear application, defect indications were obtained by eddy current examination in two of the tubes. From the eddy current examination results, accurate sizing and orientation of these defects could not be determined. Hence a complementary inspection method was required for better characterisation of defects in the two tubes. Even though ultrasonic testing is a most promising technique for detection and characterization of defects, the interpretation of results with A-scan presentation, relies heavily on the skill and experience of the operator performing the test, which comes only by extensive training [1]. This problem is still complicated in the case of thin walled tubes since resolution achievable is poor due to small wall thickness and diameter, and also due to poor signal-to-noise ratio obtainable from fine size defects

Generalized Mittag-Leffler Distributions and Processes for Applications in Astrophysics and Time Series Modeling

Geometric generalized Mittag-Leffler distributions having the Laplace transform $\frac{1}{1+\beta\log(1+t^\alpha)},00$ is introduced and its properties are discussed. Autoregressive processes with Mittag-Leffler and geometric generalized Mittag-Leffler marginal distributions are developed. Haubold and Mathai (2000) derived a closed form representation of the fractional kinetic equation and thermonuclear function in terms of Mittag-Leffler function. Saxena et al (2002, 2004a,b) extended the result and derived the solutions of a number of fractional kinetic equations in terms of generalized Mittag-Leffler functions. These results are useful in explaining various fundamental laws of physics. Here we develop first-order autoregressive time series models and the properties are explored. The results have applications in various areas like astrophysics, space sciences, meteorology, financial modeling and reliability modeling.Comment: 12 pages, LaTe

Meeting the challenges related to material issues in chemical industries

Reliable performance and profitability are two important requirements for any chemical industry. In order to achieve high level of reliability and excellent performance, several issues related to design, materials selection, fabrication, quality assurance, transport, storage, inputs from condition monitoring, failure analysis etc. have to be adequately addressed and implemented. Technology related to nondestructive testing and monitoring of the plant is also essential for precise identification of defect sites and to take appropriate remedial decision regarding repair, replacement or modification of process conditions. The interdisciplinary holistic approach enhances the life of critical engineering components in chemical plants. Further, understanding the failure modes of the components through the analysis of failed components throws light on the choice of appropriate preventive measures to be taken well in advance, to have a control over the overall health of the plant. The failure analysis also leads to better design modification and condition monitoring methodologies, for the next generation components and plants. At the Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam, a unique combination of the expertise in design, materials selection, fabrication, NDT development, condition monitoring, life prediction and failure analysis exists to obtain desired results for achieving high levels of reliability and performance assessment of critical engineering components in chemical industries. Case studies related to design, materials selection and fabrication aspects of critical components in nuclear fuel reprocessing plants, NDT development and condition monitoring of various components of nuclear power plants, and important failure investigations on critical engineering components in chemical and allied industries are discussed in this paper. Future directions are identified and planned approaches are briefly described

Striding towards self sustainability using Aluminium from Tanzanian kaolin for combination Tanning system

Content: Sustainability is a key factor which control future leather manufacture. Developing several new technologies is one of the primary agenda for sustainability. However, developing countries are facing several challenges which not only limited to best practice technologies but also finding self sustainability in maximizing the available resources. In the present study, an attempt has been made to explore the potential resource of aluminium from kaolin of Pugu hills, Tanzania for combination tanning. Though, extraction of aluminium from several resources are available, there is limited literature pertaining to Tanzania resources. Moreover, the extracted aluminium is basified and studied for its tanning efficiency. Diffraction and vibrational spectroscopic studies were carried out to assess the confirmation of extracted aluminium. Combination tanning has been carried out with vegetable tannins and dialdehyde starch tanning chemicals, which are from natural resources. Leathers tanned with aluminum and wattle resulted with a shrinkage temperature of 118ºC as compared to Al-Dialdehyde starch leathers showed around 90-100ºC. Physical strength characteristics such as tensile, tear and grain crack strength met the standard norms. Grain surface of leathers are found to be smooth which has been confirmed through microscopic studies. The study provides a new insight on accomplishing self sustainability through available resources and manufacture of eco-friendly system. Take-Away: 1. Tanzania is endowed with massive kaolin rich in aluminium, which is potential for application in leather industry for sustainable development of leather industry 2. The combination tanning system using aluminium from Tanzania kaolin with wattle tannins or Dialdehyde starch imparts leather with both physical and organoleptic properties that meet the stipulated norms 3. This new tanning system provides new insight on ecofriendly tanning system for the sustainability of leather industry