Integrated product and its extended enterprise network design using lean principles

Recently, many system integration companies have begun to intensely focus on suppliers\u27 involvement in the product realization process to enhance their competitiveness. The product architecture has a huge impact on the efficiency of the integrator\u27s supplier network. One of the ways to enhance efficiency is to implement the lean principles while creating a collaborative design/manufacturing/supply chain environment. In this study, two distinct stages of the product realization process, namely, design stage and production stage are considered for determining the design and production supplier networks --Abstract, page iv

Three-level neutral point-clamped (NPC) traction inverter drive for electric vehicles

The motivation of this project was to develop a three level neutral point clamped (NPC) traction inverter for a permanent magnet synchronous machine drive. The three-level inverter helps to reduce the total inverter losses at higher switching frequencies, compared to a two-level inverter for electric vehicle applications. The three-level inverter has also more power switches compared to the two-level inverter. This helps to reduce the voltage stress across the switches and the machine winding. In addition, it also allows an increase in the DC-link voltage, which in turn helps to reduce the DC-link current, phase conductor size and the associated losses. Moreover, at higher DC-bus voltages the power switches will have lower thermal stress when compared to the 2-level. However, the NPC inverter topologies have an inherent problem of DC-link voltage balancing. In the initial part of this thesis, a novel space vector based DC-link voltage balancing strategy is proposed. This strategy can keep the two DC-link capacitor voltages balanced during transient changes in both speed and torque. The performance of the three-level inverter system is then compared with a two-level inverter based drive to validate its performance improvement. The results showed a significant reduction in total voltage and current harmonic distortions, reduced total inverter losses (by 2/3rd) and was even was able to keep the neutral point fluctuation low at all operating load power factor conditions. The second motivation of this thesis was to reduce the computational time in the real-time implementation of the control logic. For this purpose, a modified carrier and hybrid-carrier based PWM strategy was proposed, which also kept the DC-link capacitor voltages balanced. The modified carrier based strategy was able to reduce the switching losses compared to the conventional strategies, while the hybrid-carrier based strategy kept the advantages of both carrier and the space vector techniques. Finally, a performance comparison study was carried out to compare the total harmonic distortion, switching loss distribution, and total inverter loss of all the four proposed strategies

ANTIOXIDATIVE AND FREE RADICAL SCAVENGING POTENTIALS OF CYCLOSORUS INTERRUPTUS (WILLD.) H. ITÔ AND PRONEPHRIUM NUDATUM (ROXB. EX GRIFF.) HOLTTUM

Objectives: The work aims to screen the antioxidative potentials of different crude extracts of the fronds of two medicinally important pteridophytes of Southern Assam, India, namely, Cyclosorus interruptus (Willd.) H. Itô and Pronephrium nudatum (Roxb. ex Griff.) Holttum. Methods: Frond extracts of the pteridophytes were prepared by Soxhlet hot extraction method. Total phenolic content (TPC) and total flavonoid content (TFC) of the hexane, ethyl acetate, acetone, and methanol extracts of the fronds of the plants were done by following standard protocol. In vitro assessment of the antioxidative behavior of the extracts was performed using standard 2,2-diphenyl-1-picrylhydrazyl scavenging assay, reducing power assay, metal chelating assay, hydroxyl, superoxide, and 2,2’- azino-bis (3-ethylbenzothiazoline - 6 – sulfonic acid) radical scavenging methods in different in vitro systems. Results: Preliminary phytochemical analysis implicated the presence of phenolic and flavonoid compounds in all the frond extracts. The methanol extract of the fronds of both the plants showed maximum phenolic and flavonoid contents in comparison to the other extracts, however, that of C. interruptus was found to be higher than P. nudatum. Antioxidative potentials of the said extracts were also found to be impressive and noteworthy. The decreasing order of the antioxidative efficacies of the extracts was found to be same as that of TPC and TFC of the extracts. Conclusion: It is pertinent to comment that the methanol extract of the fronds of both the plants may be treated as a potential source of natural antioxidants

Supramolecular hydrogen-bonded structure of a 1:2 adduct of melamine with boric acid

Abstract Boric acid (B) forms a 2:1 hydrogen-bond adduct, M·2B, with melamine (M), wherein, a finite tetrameric ribbon of boric acid forms hydrogen bonds with the nitrogen donor sites of M. Hydrogen-bonded layers of B and M in the bc-plane are connected by boric acid units along the a-axis to give a three dimensional structure. Interestingly, one of the amino groups of M does not participate in hydrogen bonding unlike all the hydroxyl groups of B.

Electric and magnetic polarizabilities of hexagonal Ln2CuTiO6 (Ln=Y, Dy, Ho, Er and Yb)

We investigated the rare-earth transition metal oxide series, Ln2CuTiO6 (Ln=Y, Dy, Ho, Er and Yb), crystallizing in the hexagonal structure with non-centrosymmetric P63cm space group for possible occurrences of multiferroic properties. Our results show that while these compounds, except Ln=Y, exhibit a low temperature antiferromagnetic transition due to the ordering of the rare-earth moments, the expected ferroelectric transition is frustrated by the large size difference between Cu and Ti at the B-site. Interestingly, this leads these compounds to attain a rare and unique combination of desirable paraelectric properties with high dielectric constants, low losses and weak temperature and frequency dependencies. First-principles calculations establish these exceptional properties result from a combination of two effects. A significant difference in the MO5 polyhedral sizes for M = Cu and M = Ti suppress the expected co-operative tilt pattern of these polyhedra, required for the ferroelectric transition, leading to relatively large values of the dielectric constant for every compound investigated in this series. Additionally, it is shown that the majority contribution to the dielectric constant arises from intermediate-frequency polar vibrational modes, making it relatively stable against any temperature variation. Changes in the temperature stability of the dielectric constant amongst different members of this series are shown to arise from changes in relative contributions from soft polar modes.Comment: Accepted for publication in Phys. Rev. B (21 pages, 2 Table, 8 Figures

IL1B Induced Smad 7 Negatively Regulates Gastrin Expression

BACKGROUND: Helicobacter pylori elicited IL1B is one of the various modulators responsible for perturbation of acid secretion in gut. We have earlier reported that IL1B activated NFkB downregulates gastrin, a major modulator of acid secretion. However, we hypothesized that regulation of gastrin by IL1B would depend on the cell's ability to integrate inputs from multiple signaling pathways to generate appropriate biological response. PRINCIPAL FINDING: In this study, we report that IL1B induces Smad 7 expression by about 4.5 fold in gastric carcinoma cell line, AGS. Smad 7 resulted in transcriptional repression of gastrin promoter by about 6.5 fold when co-transfected with Smad 7 expression vector and gastrin-promoter luciferase in AGS cells. IL1B inhibited phosphorylation of Smad 3 and subsequently interfered with nuclear translocation of the positive Smad complex, thus occluding it off the gastrin promoter. IL1B promoter polymorphisms (-511T/-31C IL1B) are known to be associated with H. pylori associated gastro-duodenal ulcer. We observed that IL1B expressed from -31T promoter driven IL1B cDNA elicited 3.5 fold more Smad 7 than that expressed from the IL1B-31C variant in AGS cells. This differential activation of Smad 7 by IL1B promoter variants translated into differential downregulation of gastrin expression. We further analyzed Smad 7, NFkB, IL1B and gastrin expression in antral gut biopsy samples of patients with H. pylori associated duodenal ulcer and normal individuals. We observed that individuals with duodenal ulcer had significantly lower levels of IL1B, Smad 7, NFkB and corresponding higher level of gastrin expression. CONCLUSION: Pro-inflammatory cytokine IL1B repress gastrin expression by activating Smad 7 and subsequent inhibition of nuclear localization of Smad 3/4 complex. Polymorphic promoter variants of IL1B gene can modulate the IL1B expression which resulted in differential activation Smad 7 and consequent repression of gastrin expression, respectively. Analysis of H. pylori infected duodenal ulcer patient's gut biopsy samples also supported this observation

Mahatma Gandhi and the Prisoner’s Dilemma: Strategic Civil Disobedience and Great Britain’s Great Loss of Empire in India

This paper examines the relationship between statutory monopoly and collective action as a multi-person assurance game culminating in an end to British Empire in India. In a simple theoretical model, it is demonstrated whether or not a collective good enjoys (or is perceived to enjoy) pure jointness of production and why the evolutionary stable strategy of non-violence was supposed to work on the principle that the coordinated reaction of a ethnically differentiated religious crowd to a conflict between two parties (of colonizer and colonized) over confiscatory salt taxation would significantly affect its course. Following Mancur Olson (1965) and Dennis Chong (1991), a model of strategic civil disobedience is created which is used to demonstrate how collective action can be used to produce an all-or-nothing public good to achieve economic and political independence

Damage detection in structures using measured frequency response function data

Modern engineering structures such as offshore oil platforms, transmission towers, bridges and aircraft frames are regularly monitored and maintained in order to avert catastrophic failure. Despite our best efforts, sporadic failures, which may have disastrous consequences in terms of human life and resources, still occur. It is therefore important to develop techniques which lead to significant improvements in the reliability of the structures. A challenging area of structural dynamics research is concerned with the development and practical implementation of monitoring systems which can identify and quantify damage as it occurs in a structure. The development of a number of techniques that contribute to providing means to detect structural damage is the goal of the work presented in this thesis