38 research outputs found
Modeling and Analysis of Active Front-End Induction Motor Drive for Reactive Power Compensation
No full textIn this thesis, an active front end induction motor drive for reactive power compensation is analyzed. The classical vector control approach for high performance control of an induction motor drive is a well established industry standard today. The same idea of decoupled control is extended to the line-side PWM converter for achieving better dynamic performance.
The system model is obtained using d-q rotating frame theory. The iqe component of line currents is used to control the reactive power. The idecomponent is used to control the dc-link voltage and also to supply active power required by the motor. A high gain feedback controller with input-output linearization is presented to remove coupling between iqe and ide currents. A load power feed-forward loop is added to the dc-link voltage controller for fast dynamic response.
The drive performance is analyzed to define system specifications. The motor acceleration, deceleration, and variable power factor operation (reactive power compensation) of the active drive system are demonstrated. The motor load is varied from no load to full load in steps of 10% each. For each step the device currents, switching power loss, line harmonics, and dc-link ripples are plotted. This data is used to derive conclusions that define system specifications and also state operating limits.
The control of the drive system is implemented in MATLAB-SIMULINK. The complete system hardware is implemented in commercially available simulation tool, PSIM. The two software packages are interlinked using an interface module
Spiked instantons from intersecting D-branes
No full textAbstractThe moduli space of spiked instantons that arises in the context of the BPS/CFT correspondence [22] is realised as the moduli space of classical vacua, i.e. low-energy open string field configurations, of a certain stack of intersecting D1-branes and D5-branes in Type IIB string theory. The presence of a constant B-field induces an interesting dynamics involving the tachyon condensation
The Politics of Metaphysics in Indian Philosophy
No full textFrom ancient times to the present, concerning the Indian subcontinent, the caste system has been occupying every sphere of Indian society, culture, religion, philosophy, etc. The caste problem has influenced every philosophical discourse from the classical era to contemporary times. Most of the modern Indian political thinkers either justified the caste system or critiqued casteism but strongly supported the "Varņa-system," hence casteism from the backdoor, or gave no place to the problem of caste in their writings. In India, any discourse on philosophy in contemporary times cannot be expected to be untouched by the flavor of classical Indian philosophical thoughts. In this article, the author would argue that, regarding classical Indian philosophy, it has been a general perception that the roots of all the schools of Indian philosophy lie in the Upanishads. Many prominent scholars of modern India strongly advocated this view, e.g., Swami Vivekananda, S Radhakrishnan, P V Kane, R D Ranade, etc. Still, one thing that can be observed in the methods of all these scholars is that they all show the similarities between the metaphysical theories of Upanishads and that of any other school of Indian philosophy which they wish to show been rooted in Upanishads; they conclude that the roots of all the schools of Indian philosophy lie in Upanishads; while ignoring their practical repercussions on the Indian social structure of the time. In this contrast, the author will try to deconstruct the central arguments of the prominent colonial and modern Indian thinkers and will attempt to demonstrate what has disappeared from the entire scenario of the reconstruction of the history of Indian philosophy, i.e., "emergence of Buddhism as an alternative to Vedic-Brāhmanism," "the co-opting pattern of Brāhmanism" by exploring the historicity of its foundational metaphysical concepts, and "how that Brāhmanical pattern is used in the modern era.
Biomethanation of vegetable market waste in an anaerobic baffled reactor: Effect of effluent recirculation and carbon mass balance analysis
No full textIn the present study, feasibility of biomethanation of vegetable market waste in a 4-chambered anaerobic
baffled reactor (ABR) was investigated at 30 d hydraulic retention time and organic loading rate of
0.5 g VS/L/d for one year. Indicators of process stability viz., butyrate/acetate and propionate/acetate
ratios were consistent with phase separation in the different chambers, which remained unaltered even
during recirculation of effluent. Chemical oxygen demand (COD) and volatile solids (VS) removal
efficiencies were observed to be consistently high (above 90%). Corresponding biogas and methane yields
of 0.7–0.8 L/g VS added/d and 0.42–52 L/g VS added/d respectively were among the highest reported in
case of AD of vegetable waste in an ABR. Process efficiency of the ABR for vegetable waste methanation,
which is indicated by carbon recovery factor showed that, nearly 96.7% of the input carbon considered for
mass balance was accounted for in the product
Technological Advances for Treating Municipal waste
No full textMunicipal solid waste management (MSWM) is a challenging task, which has grown immensely due to the changes in lifestyle throughout the world.In developed countries, appropriate norms and adequate administrative and financial resources clubbed with innovative technologies are some driving force, which is proving helpful in MSWM. However, an ever-changing waste composition and some techno-environmental issues still exist. On the other hand, in developing countries in the absence of these provisions, MSWM is becoming a key of socioeconomic development. Due to variations in waste composition, there is a need to adopt multiple means of waste disposal. It thus demands revisiting the available know-how and making the required corrections to suit the grossly ill-classified wastes. In this chapter, characteristic components of MSW and possibilities of their disposal through thermal and biological treatment technology are reviewed.The generation of renewable energy while treating waste, makes disposal an organized and attractive option
Enhanced electrical and optical properties of room temperature deposited Aluminium doped Zinc Oxide (AZO) thin films by excimer laser annealing
No full textHigh quality transparent conductive oxides (TCOs) often require a high thermal budget fabrication process. In this study, Excimer Laser Annealing (ELA) at a wavelength of 248 nm has been explored as a processing mechanism to facilitate low thermal budget fabrication of high quality aluminium doped zinc oxide (AZO) thin films. 180 nm thick AZO films were prepared by radio frequency magnetron sputtering at room temperature on fused silica substrates. The effects of the applied RF power and the sputtering pressure on the outcome of ELA at different laser energy densities and number of pulses have been investigated. AZO films deposited with no intentional heating at 180 W, and at 2 mTorr of 0.2% oxygen in argon were selected as the optimum as-deposited films in this work, with a resistivity of 1×10−3 Ω.cm, and an average visible transmission of 85%. ELA was found to result in noticeably reduced resistivity of 5×10−4 Ω.cm, and enhancing the average visible transmission to 90% when AZO is processed with 5 pulses at 125 mJ/cm2. Therefore, the combination of RF magnetron sputtering and ELA, both low thermal budget and scalable techniques, can provide a viable fabrication route of high quality AZO films for use as transparent electrodes
Chemical Composition, Sequence Context, and Base-Pairing Potential of Posttranscriptional Modifications at the Wobble Position of the tRNA Anticodon Loop
No full textIt is well accepted that RNA is frequently and diversely modified, with the anticodon stem loop of transfer (tRNA) holding the largest number and types of chemical substitutions. Nevertheless, the roles these modifications play in cells remain unclear. The present study consolidates and expands our current knowledge of tRNA modifications at position 34 (wobble position) using a range of bioinformatics and computational techniques. Sequence analysis on 474 tRNAs clarifies the position 34 modifications identified to date at each parent nucleotide across all domains of life. Subsequent analysis of 1291 cryo-EM or X-ray crystal structures of ribosomal complexes led to curation of a dataset of 468 high-resolution structures of position 34 base-pair interactions with messenger (mRNA). Despite underscoring that structural information is scarce for several canonical base–pairing combinations and nucleotide modifications, the structural data hints that modifications can have differential impact of the base pairing at position 34. Due to limited experimental structural data for position 34 modifications, density functional theory (DFT) calculations were used to characterize 120 pairs involving canonical and/or modified nucleobases, revealing that some chemical substituents do not impact base-pairing properties of parent nucleotides regardless of modification size, while others slightly alter inherent base pairing or afford completely new base-pairing properties to fine-tune tRNA–mRNA interactions. Overall, consolidation of previous and our new data suggests that position 34 modifications likely regulate translation in several ways and underscores the importance of incorporating computational analyses in the future analysis pipeline as modifications are identified.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
Оценка качества и идентификация отпечатков пальцев путем анализа структурных свойств изображения
No full textThe paper addresses the problem of assessing the quality of fingerprint images using spatial analysis methods. The author proposes using the previously developed mathematical model to describe the set of magnitudes of the image gradient. The model is based on the two-parameter Weibull distribution. The author proposes two approaches to assess the quality of fingerprints. The first approach is implemented by the so-called “Full reference method”, which compares the Weibull distribution parameters’ values of statistical estimates. The results of identifying sweat pores using this method are presented. The second approach is called the “No-Reference method” and is used to assess fingerprints’ quality when analyzing and identifying the information content of their individual sections. It is proposed to use an image blur map as a quality characteristic and a statistical estimate of the Weibull distribution shape parameter as a measure of the blur. The shape parameter is estimated at each image point by the combination of magnitudes of the image gradient in the vicinity of the point; in this, the previously developed blur mapping technique is applied. The specific examples illustrate effectiveness of the proposed approaches.Рассмотрена задача оценки качества изображения отпечатков пальцев с применением пространственных методов анализа. Предложено использовать математическую модель, разработанную ранее для описания совокупности магнитуд градиента изображения. Модель основана на двухпараметрическом распределении Вейбулла. Для оценки качества отпечатков пальцев предложены два подхода. Первый реализуется с помощью так называемого метода сравнения с эталоном (Full Reference), когда сравниваются значения статистических оценок параметров распределения Вейбулла. Приведены результаты решения задачи идентификации потовых пор этим методом. Второй подход называется «безэталонным» (No-Reference) и применяется для оценки качества отпечатков при анализе и выделении информативности их отдельных участков. В качестве характеристики качества предлагается использовать карту размытости изображения, а в качестве меры размытости – статистическую оценку параметра формы распределения Вейбулла. Параметр формы оценивается в каждой точке изображения по совокупности магнитуд градиента изображения в окрестности точки, при этом применяется разработанная ранее методика построения карты размытости. Эффективность предложенных подходов иллюстрируется конкретными примерами
