1,722,737 research outputs found
Genetics of resistance to stem rust against Indian races in wheat varieties, Kundan and UP 2338
No full textThe parents, F1 and F2 individuals of the crosses Kundan x Agra Local, UP 2338 x Agra Local and Kundan x UP 2338 were screened to study the genetics of resistance in the Ug99-resistant varieties of wheat, Kundan and UP 2338 against two Indian stem rust pathotypes 40A (62G29) and 122 (7G11). Against race 40A (62G29), the variety Kundan did not have any resistance alleles, whereas, UP 2338 exhibited the presence of dominant resistance gene. The 195 F2 individuals of the cross UP 2338 × Agra Local and Kundan × UP 2338 segregated at a ratio of 3(R):1(S). Against stem rust pathotype 122 (7G11), the variety Kundan displayed monogenic dominant resistance. The resistance x resistance cross Kundan x UP 2338 also displayed resistance reaction in the F2 generation with no segregation indicating the presence of common gene in both the parents (Kundan and UP 2338) conferring resistance against the pathotype 122
Confirming the cold diffusion bonding of gold in 19<sup>th</sup> century <i>kundan </i>settings
No full textThis paper investigates the microstructural features of Indian gold settings know as kundan using xenon plasma focused ion beam (pFIB), electron backscatter diffraction (EBSD) and energy dispersive x-ray spectroscopy (EDX). Testing sought to determine the purity of the gold foils in kundan settings and if they form diffusion bonds, by cold-working. Three, 19th century samples of Indian kundan with reliable provenance were analysed. The samples were from the hilts of two Indian daggers given as diplomatic gifts to Albert Edward, Prince of Wales, during his tour of the Indian subcontinent in 1875-6. It was confirmed that diffusion bonding does occur in the cold-worked gold during the kundan process. Work hardening and mechanical condensing also contribute to the mechanical integrity of kundan settings. The settings were found to comprise of near pure gold foils of ~10 µm thickness.</p
High Efficiency Power Converters for Vehicular Applications
Get PDFThe use of power electronics in the electrical propulsion systems leads to the optimal and efficient utilization of the traction motors and the energy sources (batteries and/or fuel cells) through the recourse to suitable power converters and their proper control. Power electronics is also used for implementing the multiple conversions of the energy delivered by the sources to feed the various loads, most of them requiring different waveforms of voltage (ac or dc) and/or different levels of voltage. This work focuses on the solutions aimed at improving the efficiency of power converters for vehicular applications, which is of great importance because of the limited amount of energy that can be stored in the electric vehicles. The study takes into consideration both the traction applications and the battery charging applications whether it is done by conductive means or by wireless power transfer (WPT) systems. The improvement in traction drive efficiency results in an increment of the drivetrain efficiency of the vehicle, leading to an extension in the driving range, while the employment of efficient power converters is required to charge batteries with increasingly large capacity. The losses of power devices are even more significant when they operate at high frequencies to compact the size of the filter elements and/or the transformers. The losses of power devices can be minimized by making the commutation soft or by replacing the conventional devices with the new generation devices based on wide bandgap (WBG) semiconductor materials. In this work, the properties of the WBG semiconductor materials are illustrated and the operation of the devices based on these materials are analyzed to grasp better their characteristics and performance. The losses of individual devices (i.e. diode, IGBT, MOSFET) as well as the operation of power converters for various applications are examined in detail.
To evaluate the performance of the SiC devices in electric vehicle applications, an AC traction drive for the propulsion of a typical compact C-class electric car has been considered. Two versions of the inverter have been investigated, one built up with conventional Si IGBTs and the other one with SiC MOSFETs, and the losses in the semiconductor devices of the two versions have been found along the standard New European Driving Cycle (NEDC). By comparing the results, it is emerged that the usage of the SiC MOSFETs reduces the losses in the traction inverter of about 5%, yielding an equal increase in the car range. To complete the study, calculation of the efficiency has been extended to the whole traction drive, including the traction motor and the gear.
Afterwards, a power factor correction (PFC) circuit, which is commonly used to mitigate the distortion in line current, has been studied. The study is started by considering the basic and the interleaved PFC configurations and by defining their circuit parameters. After selecting the interleaved configuration, the magnitude of voltages and currents in the PFC rectifier has been determined and the values obtained have been verified by a power circuit simulation software. The digital signal processing (DSP) has been also studied as it is used for the control operation of the PFC. At last, a prototype of PFC rectifier with interleaved configuration is designed. The design process and the specification of the components are described in brief.
A prototype of synchronous rectifier (SR) is designed for the output stage of a WPT system. With respect to conventional rectifiers, in SRs the diodes are replaced by MOSFETs with their antiparallel diodes. MOSFETs are bidirectional devices that conduct with a low voltage drop. During the dead time, the diodes in antiparallel to the MOSFETs are conducting. At the end of dead-time, signals are applied at the MOSFET gates that make conducting all along the remaining period, thus reducing the conduction losses. The dead-time length is optimized by using fast switching devices based on SiC semiconductor materials. The prototype is designed and tested at the line frequency. The experimental results obtained from the prototype corroborate both the analytical results and the simulation results. As SR exhibits is working with high efficiency at the line frequency, it is expected that at the higher operating frequencies of the WPT systems, the performance of SR will be even better.
A DC-DC isolated power converters used to setup the battery charger through wire system are studied. Two topologies of DC-DC converters, i.e. Dual Active Bridge (DAB) and Single Active Bridge (SAB) converters, are considered. For both the topologies operation are described at steady state. For SAB converter, two possible modes of operation are examined: discontinuous current conduction (DCM) and continuous current conduction (CCM). Soft-switching operation of both SAB and DAB converters, obtained by the insertion of auxiliary capacitors, is analyzed. Moreover, the soft-switching operating zone for the two converters are found as a function of the their output voltages and currents. Finally, the comparative analysis of soft-switching operation of SAB versus DAB converter is presented.
The thesis work has been carried out at the Laboratory of “Electric Systems for Automation and Automotive” headed by Prof. Giuseppe Buja. The laboratory belongs to the Department of Industrial Engineering of the University of Padova, Italy
Lower Ordovician (Volkhovian-Kundan) conodonts from Hagudden, northern Oeland, Sweden.
No full textThis paper presents taxonomical description of Early Ordovician conodonts recovered from the limestones at Hagudden, in northern Oeland (Sweden). 33 samples yielded about 20.000 conodont elements. 18 genera and 36 species are described. Two genera are emended and redefined in terms of multielement taxonomy. Two new species are described. The fauna is typical of the Baltic region. The conodont zones are correlated with the trilobite zones. The faunas of the Volkhovian Stage and the Hunderumian Substage and Valastean Substage of the Kundan Stage are discussed
PIA904553 Supplemental Material1 - Supplemental material for Improved performance of a nanorefrigerant-based vapor compression refrigeration system: A new alternative
No full textSupplemental material, PIA904553 Supplemental Material1 for Improved performance of a nanorefrigerant-based vapor compression refrigeration system: A new alternative by Lal Kundan and Kuljeet Singh in Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
PIA904553 Supplemental Material2 - Supplemental material for Improved performance of a nanorefrigerant-based vapor compression refrigeration system: A new alternative
No full textSupplemental material, PIA904553 Supplemental Material2 for Improved performance of a nanorefrigerant-based vapor compression refrigeration system: A new alternative by Lal Kundan and Kuljeet Singh in Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy</p
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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