Magnetocaloric effect and nature of magnetic transition in nanoscale Pr0.5Ca0.5MnO3

Systematic measurements pertinent to the magnetocaloric effect and nature of magnetic transition around the transition temperature are performed in the 10 nm Pr0.5Ca0.5MnO3 nanoparticles (PCMO10) . Maxwell relation is employed to estimate the change in magnetic entropy. At Curie temperature TC, 83.5 K, the change in magnetic entropy discloses a typical variation with a value 0.57 J/kg K, and is found to be magnetic field dependent. From the area under the curve Delta S vs T, the refrigeration capacity is calculated at TC, 83.5 K and it is found to be 7.01 J/kg. Arrott plots infer that due to the competition between the ferromagnetic and anti ferromagnetic interactions, the magnetic phase transition in PCMO10 is broadly spread over both in temperature as well as in magnetic field coordinates. Upon tuning the particle size, size distribution, morphology, and relative fraction of magnetic phases, it may be possible to enhance the magnetocalorific effect further in PCMO10.Comment: Accepted (Journal of Applied Physics) (In press

Resources of Ribbon Fish and Cat Fish off the South West Coast of lndia

The acoustic surveys and fishing experiments conducted by the research vessels RASTRELLIGER and SARDINELLA of the Pelagic Fishery Project from Ratnagiri to the Gulf of Mannar for the past four years have considerably enhanced our knowledge of the pelagic fishery resources, their abundance and seasonal distribution and possible methods of exploitation (Anonymous 1974, 1975 & 1976). The average annual landings of ribbon fish and cat fish for the past ten years with 78,000tonnes form only 7.7% of the total marine fish production in India

Dynamic response of exchange bias in graphene nanoribbons

The dynamics of magnetic hysteresis, including the training effect and the field sweep rate dependence of the exchange bias, is experimentally investigated in exchange-coupled potassium split graphene nanoribbons (GNRs). We find that, at low field sweep rate, the pronounced absolute training effect is present over a large number of cycles. This is reflected in a gradual decrease of the exchange bias with the sequential field cycling. However, at high field sweep rate above 0.5 T/min, the training effect is not prominent. With the increase in field sweep rate, the average value of exchange bias field grows and is found to follow power law behavior. The response of the exchange bias field to the field sweep rate variation is linked to the difference in the time it takes to perform a hysteresis loop measurement compared with the relaxation time of the anti-ferromagnetically aligned spins. The present results may broaden our current understanding of magnetism of GNRs and would be helpful in establishing the GNRs based spintronic devices.Comment: Accepted Applied Physics Letters (In press

Martensite-like transition and spin-glass behavior in nanocrystalline Pr0.5Ca0.5MnO3

We report on isothermal pulsed (20 ms) field magnetization, temperature dependent AC - susceptibility, and the static low magnetic field measurements carried out on 10 nm sized Pr0.5Ca0.5MnO3 nanoparticles (PCMO10). The saturation field for the magnetization of PCMO10 (~ 250 kOe) is found to be reduced in comparison with that of bulk PCMO (~300 kOe). With increasing temperature, the critical magnetic field required to 'melt' the residual charge-ordered phase decays exponentially while the field transition range broadens, which is indicative of a Martensite-like transition. The AC - susceptibility data indicate the presence of a frequency-dependent freezing temperature, satisfying the conventional Vogel-Fulcher and power laws, pointing to the existence of a spin-glass-like disordered magnetic phase. The present results lead to a better understanding of manganite physics and might prove helpful for practical applications

Prawn (Penaeus monodon) seed exploited along the coast of Visakhapatnam and Vizianagaram districts of east coast of Andhra Pradesh

The prawn business proved the best among all the businesses because of its profit earned on investment and high value in export trade. The demand for prawns is increasing day by day. Many prawn and acquaculture farms have come up in Visakhapatnam and Vizianagaram districts of Andhra Pradesh. To meet the demand the fishermen folk started exploitation of prawn seed from the surf zone

Design Development and Analysis Of Two Wheeler Eco Friendly Plastic Carburetor With Rapid Prototyping

The design development and analysis of carburetor has been carry out by applying structural and thermal loads. The present work particularly deals with the drafting and designing of carburetor using plastic materials which can be manufactured with rapid prototyping to increase mass production. My main aim is to prevent the component from getting corroded or undergoing corrosion. Replacing metal components with plastic ones can offer some important bondage. Unlike metals, plastic materials can be modified to better suit. And also manufactured by using RP technique the life of the product increases of course when fuel injectors are replaced it as the main fuel input system, it had evolve into a complicated, sophisticated, expensive system. Carburetors are still found on automobiles, many small engines like those on lawn movers and model airplanes still use carburetors. It is to keep the cost of the engine down and it is very cheap to manufacture while fuel injectors requires more costly control systems

Structural and Thermal Analysis of Disc Brake With and Without Cross Drilled Rotor

The disc brake is a device for slowing or stopping the rotation of a wheel. A brake disc (or rotor), usually made of cast iron or ceramic composites (including carbon, Kevlar and silica), is connected to the wheel and/or the axle. To stop the wheel, friction material in the form of brake pads (mounted on a device called a brake caliper) is forced mechanically, hydraulically, pneumatically or electromagnetically against both sides of the disc. Friction causes the disc and attached wheel to slow or stop. Brakes convert friction to heat, but if the brakes get too hot, they will cease to work because they cannot dissipate enough heat. This condition of failure is known as brake fade. Disc brakes are exposed to large thermal stresses during routine braking and extraordinary thermal stresses during hard braking. The aim of the project is to model a disc brake used. Coupled field analysis (Structural + Thermal) is done on the disc brake. The materials used are Cast Iron, stainless steel and aluminum alloy. Analysis is also done by changing the design of disc brake. Actual disc brake has no holes, design is changed by giving holes in the disc brake for more heat dissipation. Modeling is done in Pro/Engineer and analysis is done in Ansys

Dynamics Of Multi layered Composite Shell With Shape Memory Alloys

The use of different composite materials has been continuously growing in recent years. Although many applications for composite materials have been identified. Extensive research is still being carried out in order to expand this field. New materials and technologies have been researched. One such new application is the integration of shape memory materials within composite materials. In this study certain aspects of the dynamic behavior of a multilayered composite shell with shape memory alloy (SMA) wires have been investigated. The influence of SMA wires, the orientation and the thickness to diameter ratio and different boundary conditions, on changes in critical load, the natural frequencies and modes of vibration of the shell have been studied and discussed in the present study. The results presented are obtained by the use of finite element method. The analysis both static and modal has been carried out using ANSYS 12.0. The shape memory alloys possess the inherent ability to change their material properties in particularly their young’s modulus, damping capacity as well as great capacity for the generation of large internal forces. Integrating SMA’s within composite material structures potentially allow the active control of certain static and dynamic behaviour of the integrated structures. Precise tuning of SMA components enables the control of certain static and dynamic characteristics of composite material structures, notably deflections and shape, natural frequencies and modes of vibrations. SMA components embedded into or bonded to composite material structures can be utilized in two different ways. They are Active Property Tuning Method and Active Strain energy Tuning Method. These techniques induces a special property in SMA components integrated with appropriate composite material structures leads to high generation of high recovery stresses

Design and Analysis of Dry Cylinder Liners Used in Diesel Engines

A Cylinder liner is a cylindrical part to be fitted  in to an engine block to form a cylindrical space in which the piston reciprocates very smoothly. It is one of the most important functional parts to make up the interior of an engine. Generally cylinder liners are made of Cast Iron, Cast steel, Nickel CI, Nickel chrome CI. The aim of this project is to design and analyze a dry cylinder liner for Hino-X diesel engines. A Hino – X engine cylinder dry liner used in one of Ashok Leyland model manufactured by  The amount of heat generated, heat transfer rate of the component, temperature produced inside the cylinder are to be calculated using ANSYS analysis package. Various surface coatings like ceramic, aluminum alloys and Nickel chrome alloy steel are used to study the, heat flux, , thermal stresses, thermal displacement, thermal gradient ,nodal temperatures of the cylinder liner. Modeling is done in Pro/Engineer and analysis is done coupled field analysis in ansys. After comparing the results, the best coated cylinder dry liner for this type of diesel engine can be suggested