Indian Institute of Technology Bombay

About: Indian Institute of Technology Bombay is a education organization based out in Mumbai, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 16756 authors who have published 33588 publications receiving 570559 citations.

Tuned liquid dampers for controlling earthquake response of structures

Abstract: Numerical simulations of a single-degree-of-freedom (SDOF) structure, rigidly supporting a tuned liquid damper (TLD) and subjected to both real and artificially generated earthquake ground motions, show that a properly designed TLD can significantly reduce the structure's response to these motions. The TLD is a rigid, rectangular tank with shallow water in it. Its fundamental linear sloshing frequency is tuned to the structure's natural frequency. The TLD is more effective in reducing structural response as the ground excitation level increases. This is because it then dissipates more energy due to sloshing and wave breaking. A larger water-depth to tank-length ratio than previous studies suggested, which still falls within the constraint of shallow water theory, is shown to be more suitable for excitation levels expected in strong earthquake motions. A larger water-mass to structure-mass ratio is shown to be required for a TLD to remain equally effective as structural damping increases. Furthermore, the reduction in response is seen to be fairly insensitive to the bandwidth of the ground motion but is dependent on the structure's natural frequency relative to the significant ground frequencies. Finally, a practical approach is suggested for the design of a TLD to control earthquake response. Copyright © 2000 John Wiley & Sons, Ltd.

Surface controlled synthesis of MFe2O4 (M = Mn, Fe, Co, Ni and Zn) nanoparticles and their magnetic characteristics

Abstract: Engineered magnetic nanoparticles, MFe2O4 (where M = Mn, Fe, Co, Ni and Zn), of mean size 2–16 nm (standard deviation σ ≤ 15%) with controlled magnetic properties have been synthesized through a solventless thermolysis technique. In this ‘energy-efficient’ facile approach, a long-chain amine is utilized as the solvent, reducing and surface-functionalizing agent. The particle sizes between 2–9 nm are tuned by simple manipulation of the amine to precursor molar ratio while the larger sizes (12–16 nm) are attained by seed-mediated growth. The synthesized nanoparticles are magnetic and show cubic-spinel structure as characterized by HRTEM, SAED, XRD and Raman spectroscopy. The spin–orbit coupling, which induces larger magnetocrystalline anisotropy energy, leads to an increase of the blocking temperature in an order of Zn, Ni, Mn, Fe and Co. Additionally the saturation magnetization (magnetization at 2 T) of nanoparticle decreases in an order as per the periodic arrangement i.e. Mn > Fe > Co > Ni > Zn. This trend is better understood in terms of a cationic distribution of varying magnetic moments in these spinel oxides. For all the ferrites, the magnetization saturates to the bulk value at sizes ≥12 nm, indicating strict control over the dead layer thickness. The effect of surface coordination on the magnetic properties of the ferrite nanoparticles is analyzed. In contrast to trioctylphosphine oxide (TOPO) and oleic acid (OA) functionalized nanoparticles the saturation magnetization of amine protected nanoparticles is higher, which suggests a strong coupling of amine molecules to cations at the particle interface.

Creating probabilistic databases from information extraction models

Abstract: Many real-life applications depend on databases automatically curated from unstructured sources through imperfect structure extraction tools. Such databases are best treated as imprecise representations of multiple extraction possibli-ties. State-of-the-art statistical models of extraction provide a sound probability distribution over extractions but are not easy to represent and query in a relational framework. In this paper we address the challenge of approximating such distributions as imprecise data models. In particular, we investigate a model that captures both row-level and column-level uncertainty and show that this representation provides significantly better approximation compared to models that use only row or only column level uncertainty. We present efficient algorithms for finding the best approximating parameters for such a model: our algorithm exploits the structure of the model to avoid enumerating the exponential number of extraction possibilities.

Hybrid ozonation process for industrial wastewater treatment: Principles and applications: A review

Abstract: Ozone is a strong oxidant and have been effectively used for the degradation and mineralization of organic pollutants. However, the increase in the toxicity and disposal of the recalcitrant organics standalone ozonation process is not effective and sustainable solution for the treatment of industrial wastewater containing recalcitrant. It is therefore necessary to provide a summary of success of hybrid ozonation process for industrial wastewater treatment along with the reaction mechanism for enhancing the molecular ozone reactivity. The paper presents a detailed review of hybrid ozonation process as a combination of two different techniques to enhance the hydroxyl radical formation thereby increasing the process efficiency. An extensive review on the mechanism and application of these hybrid ozonation processes for degradation, mineralization, detoxification of different organic pollutants present in the industrial wastewater is reported.

An instantaneous reactive volt-ampere compensator and harmonic suppressor system

Abstract: A novel control method for a reactive volt-ampere compensator and harmonic suppressor system is proposed. It operates without sensing the reactive volt-ampere demand and nonlinearities present in the load. The compensation process is instantaneous, which is achieved without employing any complicated and involved control logic. The compensator is operated in cycle-by-cycle reference-current-controlled mode to achieve the instantaneous compensating feature. A mathematical model of the scheme is developed. Detailed analysis and simulation results are presented. A laboratory prototype of the compensator is developed to validate the results.