<p>Shiv Nadar University is a comprehensive, multidisciplinary, research-focused, and student-centric University offering a full range of academic programs at the undergraduate, postgraduate and doctoral level. With state-of-the-art infrastructure, the University comprises of academic wings, sophisticated labs, international standard sports facilities, amphitheaters, auditorium, conference rooms and smart classrooms. The University&rsquo;s goal is to become internationally recognized for the quality of its research and creative endeavors and their applicability to improving quality of life, generating new insights and expanding the boundaries of human knowledge creativity. Committed to excellence in teaching, research and service, the University aims to serve the higher education needs of India and the world beyond.</p>

Shiv Nadar University

Center for Informatics

The ant colony algorithm, mimicking the cooperative search behavior of ants in real life, has been employed for the dynamic optimization of fed-batch bioreactors. To test the capability of this new heuristic algorithm, two well-known and extensively studied systems have been chosen. The algorithm rapidly converges to optimal feed rate profiles, which maximize the overall production of the desired product and the profits in a computationally efficient and robust manner. The optimal profiles evolved are easy to implement in plant operation. The algorithm compares favorably with the other known techniques.

World University root node

Biotechnology Progress

Dynamic optimization of fed-batch bioreactors using the ant algorithm

Ab initio electronic structure calculations on Snn (n≤20) clusters using ultrasoft pseudopotentials and generalized gradient approximation for the exchange-correlation energy show the binding energies of clusters with n≥10 to be only about 11% less than the calculated bulk value. This is likely to be responsible for the recently reported [Phys. Rev. Lett. 85, 2530 (2000)] higher melting temperatures of these clusters than the bulk value. The growth behavior is found to differ from the one known for Si and Ge clusters at n≥8 but 10- and 18- to 20-atom clusters are similar. The calculated lowest energy fragmentation products are in excellent agreement with experiments and suggest that the lowest energy structures, obtained here, are close to the global minima.

Physical Review B - Condensed Matter and Materials Physics

Small clusters of tin: Atomic structures, energetics and fragmentation behavior

Physical Review Letters

Cubic Caged Clusters of Silicon Kumar, Vijay; Kawazoe, Yoshiyuki

We report metal-encapsulated caged clusters of silicon from ab initio pseudopotential plane wave calculations using generalized gradient approximation for the exchange-correlation energy. Depending upon the size of the metal (M) atom, silicon forms fullerenelike M@Si16, M = Hf, Zr and cubic M@Si14 M = Fe, Ru, Os, caged clusters. The embedding energy of the M atom is ≈ 12 eV due to strong M − Si interactions that make the cage compact. Bonding in these clusters is predominantly covalent and the highest-occupied–lowest-unoccupied molecular orbital gap is ≈ 1.5 eV. However, an exceptionally large gap (2.35 eV) is obtained for Ti@Si16 Frank-Kasper polyhedron. Interaction between these clusters is weak, making them attractive for cluster-assembled materials. {\textcopyright} 2001 American Physical Society.

Metal-encapsulated fullerenelike and cubic caged clusters of silicon

Batch Scheduling is an important problem, relevant to a large sector of the processing industries. Methods like Simulated Annealing have been traditionally used in dealing with scheduling problems that are combinatorially complex. In this paper the performance of four different annealing strategies, Simulated Annealing (SA), Threshold Acceptance (TA) and Multicanonical Jump Walk Annealing (MJWA) with and without window factor scheduling have been compared for small and large size problems. Criteria such as robustness of the method and mean deviation from the optimal solution reveal that the MJWA with window factor scheduling is far superior to SA, TA or MJWA without window factor scheduling.

Chemical Engineering Research and Design

A comparative study of annealing methods for batch scheduling problems

Scripta Materialia

Icosahedral growth and non-metal-metal transition in strontium clusters

An annular reactor packed with matrices in which the catalysts/enzyme/microorganisms are immobilized, has been simulated and the results indicate that the overall resistance and hence the conversion depend upon the Thiele modulus and another parameter, α. This parameter characterizes the ratios of the diffusion times and the ratios of length scales of the bulk liquid phase and the solid phase in the reactor shell. Analytical solutions can be obtained for linear reactions and a simplified semi-analytic method has been used for obtaining concentration profiles for nonlinear reactions. © 2001 Elsevier Science B.V. All rights reserved.

Chemical Engineering Journal

Theoretical analysis of a packed bed membrane reactor

We present results of the electronic structure and stability of calcium coverings on C60 using a linear combination of atomic orbitals and the local density functional approximation. Calculations on CaxC60 with x=12, 20 and 32 show partial charge transfer from calcium atoms to C60 and hybridization of the calcium and fullerene states. This leads to (i) a large binding energy of Ca on C60 which decreases with an increasing coverage and (ii) formation of a metallic shell on C60. The large abundance of the Ca32C60 complex is shown to be due to geometric factors in agreement with experiments. {\textcopyright} 2001 Elsevier Science B.V.

Chemical Physics Letters

Metallic coverings of calcium on C60

Recently there has been experimental evidence for structural transformations in single wall carbon nanotube bundles (SWCNTB) under pressure. We have performed ab initio electronic structure calculations on (10, 10) and (17, 0) SWCNTBs using the generalized gradient approximation for the exchange-correlation potential. When the cell shape is fixed to an hexagonal one, we find flattening of the nanotube walls in both the cases at low pressures. At higher pressures, the flattened walls buckle and ultimately cross-link. However, relaxation of the cell shape leads to a reversible first order transition of the (10, 10) SWCNTB lattice from near hexagonal to monoclinic. These results are discussed in the light of the available experimental results.

AIP Conference Proceedings

Structural transformations in single wall carbon nanotube bundles

We report high pressure Raman studies on single wall carbon nanotube bundles under hydrostatic conditions using two different pressure transmitting media, alcohol mixture and pure water. The radial and tangential modes show a blue shift when SWNT bundle is immersed in the liquids at ambient pressures. The pressure dependence of the radial modes is the same in both liquids. However, the pressure derivatives d$\omega$/dP of the tangential modes are slightly higher for the water medium. Raman results are compared with studies under non-hydrostatic conditions and with recent high-pressure X-ray studies. It is seen that the mode frequencies of the recovered sample after pressure cycling from 26 GPa are downshifted by ∼7-10 cm-1 as compared to the starting sample.