Cochin University of Science and Technology

About: Cochin University of Science and Technology is a education organization based out in Kochi, Kerala, India. It is known for research contribution in the topics: Thin film & Natural rubber. The organization has 5382 authors who have published 7690 publications receiving 103827 citations. The organization is also known as: CUSAT & Cochin University.

Enhanced Bee Colony Algorithm for Efficient Load Balancing and Scheduling in Cloud

Abstract: Cloud computing is a promising paradigm which provides resources to customers on their request with minimum cost. Cost effective scheduling and load balancing are major challenges in adopting cloud computation. Efficient load balancing methods avoids under loaded and heavy loaded conditions in datacenters. When some VMs are overloaded with several number of tasks, these tasks are migrated to the under loaded VMs of the same datacenter in order to maintain Quality of Service (QoS). This paper proposes a modification in the bee colony algorithm for efficient and effective load balancing in cloud environment. The honey bees foraging behaviour is used to balance load across virtual machines. The tasks removed from over loaded VMs are treated as honeybees and under loaded VMs are the food sources. The method also tries to minimize makespan as well as number of VM migrations. The experimental result shows that there is significant improvement in the QoS delivered to the customers.

Magnetic and optical properties of NaGdF4:Nd3+, Yb3+, Tm3+ nanocrystals with upconversion/downconversion luminescence from visible to the near-infrared second window

Abstract: We have designed and synthesized NaGdF4:Nd3+, Yb3+, Tm3+ magnetic nanophosphors with combined dual-mode downconversion (DC) and upconversion (UC) photoluminescence upon 800 nm excitation. Hexagonal-phase NaGdF4:Nd3+, Yb3+, Tm3+ nanocrystals (NCs) with an average size of 21 nm were synthesized using a solvothermal approach. Nd3+, Yb3+, Tm3+ triple-doped NaGdF4 NCs exhibit a broad range of photoluminescence peaks covering a near infrared first/second window (860–900, 1,000, and 1,060 nm), and visible emission including blue (475 nm), green (520 and 542 nm) and yellow (587 nm) after excitation at 800 nm. A mechanism involving circulation of energy over Gd3+ sublattices as bridge ions and final trapping by the initial activator ions (Nd3+) has been proposed. Penetration depth studies indicate that NIR emission is easily detected even at a large tissue thickness of 10 mm. These paramagnetic nanophosphors demonstrate a large magnetization value of 1.88 emu/g at 20 kOe and longitudinal relaxivity value of 1.2537 mM−1·S−1 as a T 1-weighted magnetic resonance imaging contrast agent. These NaGdF4:Nd3+, Yb3+, Tm3+ NCs are promising for applications in biological and magnetic resonance imaging.

On structural, optical and dielectric properties of zinc aluminate nanoparticles

Abstract: Zinc aluminate nanoparticles with average particle size of 40 nm were synthesized using a sol–gel combustion method. X-ray diffractometry result was analysed by Rietveld refinement method to establish the phase purity of the material. Different stages of phase formation of the material during the synthesis were investigated using differential scanning calorimetry and differential thermogravimetric analysis. Particle size was determined with transmission electron microscopy and the optical bandgap of the nanoparticles was determined by absorption spectroscopy in the ultraviolet-visible range. Dielectric permittivity and a.c. conductivity of the material were measured for frequencies from 100 kHz to 8 MHz in the temperature range of 30–120°C. The presence of Maxwell–Wagner type interfacial polarization was found to exist in the material and hopping of electron by means of quantum mechanical tunneling is attributed as the reason for the observed a.c. conductivity.