Hari Kumar - Academia.edu (original) (raw)

Papers by Hari Kumar

Lecture Notes in Electrical Engineering, 2020

DC micro-grids are prone to voltage instability and voltage flickers due to the incorporation of ... more DC micro-grids are prone to voltage instability and voltage flickers due to the incorporation of renewable sources, nonlinear loads, and occasional faults. DC Electric Spring (DCES) is an innovative technology preferred for mitigating the voltage distortions in power systems. This chapter explores the prospects of DCES in enhancing the power quality of Solar Photovoltaic (SPV) system fed DC micro-grid. The test system comprises of PV sources with MPPT using perturb and observe method, battery, DCES, and loads. The analysis is carried out in MATLAB/Simulink with and without DCES. The simulation results reveal the effectiveness of DCES in stabilizing the system bus voltage and extending the life time of battery in the DC micro-grid and thereby reducing the environmental hazards from the end of life disposal of batteries.

Calphad Comput Coup Phase Dia, 1998

Clinical Cancer Research, Oct 1, 2008

A35 Bin1 protein displays multiple functions such as suppression of oncogenic transformation and ... more A35 Bin1 protein displays multiple functions such as suppression of oncogenic transformation and promoting apoptosis. Loss or reduction of Bin1 expression has been evident in many human cancers including breast, prostate, and neuroblastoma (NB), and correlated with the poor outcome of patients. NB originates from precursor cells of the peripheral nervous system and is the most common extracranial solid tumor in children. The tumor is metastatic in 70% of NB patients at the time of diagnosis and the overall prognosis is particularly poor despite aggressive therapies (10-40% survival in high-risk cases). Here we show that Bin1 is frequently reduced or lost in cell lines derived from the bone marrow metastasis or abdominal mass of NB patients. To establish the direct functional link between Bin1 expression and NB, we created NB cell lines that stably overexpress Bin1. Because Bin1 has a role in apoptosis and because survival of cancer cells in the systemic circulation plays a crucial role in the multistep metastatic process, we examined the role of Bin1 in cell survival under an anchorage disrupted condition. Forced Bin1 overexpression in the stable cells increased cell death when cultured in Poly-Hema coated plates. This type of cell death is believed to be a specialized apoptosis (anoikis) . Additionally, many chemotherapeutic agents kill tumor cells via apoptosis, and we also evaluated the influence of Bin1 on chemosensitivity. The results showed that Bin1 overexpression enhances cell killing by Doxorubicin, a commonly used anticancer agent. Proteomic analyses of cell lysates from Bin1 transfectants versus the vector controls revealed differentially expressed proteins. This indicates that Bin1 may modify the metastatic behaviors and chemoresponsiveness in NB via regulating the expression levels of other cellular proteins. Our results establish Bin1 as an important factor for NB metastasis and chemosensitivity. Thus, loss of Bin1 could serve as a prognostic marker for metastatic potential and therapeutic response, and targeting Bin1 and Bin1-regulated pathways could be a rational strategy for the treatment of high-risk NB patients.

Proceedings of 1994 Power Electronics Specialist Conference - PESC'94

The studies on the photovoltaic system are extensively increasing because of a large, secure, ess... more The studies on the photovoltaic system are extensively increasing because of a large, secure, essentially exhaustible and broadly available resource as a future energy supply.

Pediatric Radiology, 2004

Journal of Surgical Research, 2008

Journal of Phase Equilibria, 1991

We consider a branching Brownian motion in which binary fission takes place only when particles a... more We consider a branching Brownian motion in which binary fission takes place only when particles are at the origin at a rate β > 0 on the local time scale. We obtain results regarding the asymptotic behaviour of the number of particles above λt at time t, for λ > 0. As a corollary, we establish the almost sure asymptotic speed of the rightmost particle. We also prove a Strong Law of Large Numbers for this catalytic branching Brownian motion.

Calphad, 2007

Complex equilibria and phase transformations involving diffusion can now be calculated quickly an... more Complex equilibria and phase transformations involving diffusion can now be calculated quickly and efficiently. Detailed examples are given for cases which involve varying degrees of non-equilibrium and therefore time-dependence. Despite very good agreement between such calculations and experimental results, many potential end-users are still not convinced that such techniques could be usefully applied to their own specific problems. Friendly graphic interface versions of calculating software are now generally available, so the authors conclude that the most likely source of the reluctance to use such tools lies in the formulation of relevant questions and the interpretation of the results. Although the potential impact of such tools was foreseen many years ago [M. Hillert, Calculation of phase equilibria, in: Conference on Phase Transformations, 1968], few changes in the relevant teaching curricula have taken into account the availability and power of such techniques. This paper has therefore been designed not only as a collection of interesting problems, but also highlights the critical steps needed to achieve a solution. Each example includes a presentation of the "real" problem, any simplifications that are needed for its solution, the adopted thermodynamic formulation, and a critical evaluation of the results. The availability of such examples should facilitate changes in subject matter that will both make it easier for the next generation of students to use these tools, and at the same time reduce the time and effort currently needed to solve such problems by less efficient methods. The first set of detailed examples includes the deoxidation of steel by aluminum; heat balance calculations associated with ladle additions to steel; the determination of conditions that avoid undesirable inclusions; the role of methane in sintering atmospheres; interface control during the physical vapour deposition of cemented carbide; oxidation of γ-TiAl materials; and simulation of the thermolysis of metallorganic precursors for Si-C-N ceramics and interface reaction of yttrium silicates with SiC-coated C/C-SiC composites for heat shield applications. A second set of examples, more dependent on competitive nucleation and growth, includes segregation and carburization in multicomponent steels and features a series of sophisticated simulatons using DICTRA software. Interfacial and strain energies become increasingly important in defining phase nucleation and morphology in such problems, but relatively little information is available compared to free energy and diffusion databases. The final section therefore demonstrates how computational thermodynamics, semi-empirical atomistic approaches and first-principles calculations are being used to aid filling this gap in our knowledge.