12,171 research outputs found
Effectiveness of multi-junction cells in near-field thermophotovoltaic devices considering additional losses
No full textThermophotovoltaic (TPV) energy converters hold substantial potential in converting thermal radiation from high-temperature emitters into electrical energy through photovoltaic (PV) cells, offering applications ranging from solar energy harvesting to waste heat recovery. Near-field TPV (NF-TPV) devices, focused on enhancing power output density (POD), exhibit unique potential by harnessing photon tunneling. However, this potential can be mitigated by additional losses arising from high photocurrent densities and corresponding scalability issues. This study comprehensively investigates the effectiveness of multi-junction-based NF-TPV devices, accounting for additional losses. We propose two approximative expressions to quantify the impact of additional losses and characterize current density-voltage curves. Verification against rigorously optimized results establishes a criterion for effective performance. Our method provides precise POD estimations even for devices with 10 or more subcells, facilitating performance analysis across parameters like vacuum gap distance, cell width, emitter temperature, and the number of subcells compared to far-field counterparts. This research outlines a roadmap for the scalable design of NF-TPV devices, emphasizing the role of multi-junction PV cells. The analytical framework we developed will provide vital insights for future high-performance TPV devices.
Thermophotonic cells in self-sustaining parallel circuits
No full textThermophotonic (TPX) cells, which integrate a light-emitting diode (LED) and a photovoltaic (PV) cell, offer potential advantages over thermophotovoltaic (TPV) cells for low-grade waste heat utilization. While TPX cells traditionally operate in an independent circuit, which requires an external battery storage unit, the self-sustaining circuit presents an appealing alternative that eliminates the need for the storage unit. In this study, we conduct a comprehensive analysis of TPX cells operating in the self-sustaining circuit. We provide clear expressions for the electrical currents flowing through the LED and PV cell, considering the different bandgaps of the LED and the PV cell. Our results reveal that the bandgap energy of the LED must exceed that of the PV cell for the TPX cell to function in a self-sustaining parallel circuit. Furthermore, we demonstrate that the performance of the TPX cell in the self-sustaining circuit improves with a narrower bandgap energy for the PV cell and a wider bandgap energy for the LED, regardless of the far-field or near-field configurations. While near-field TPX cells exhibit higher power density, they also experience decreased energy efficiency compared to far-field TPX cells. Additionally, we explore the scenario where the bandgaps of the LED and PV cell are the same, analyzing the performance of a closed-structured self-sustaining parallel circuit with multiple LEDs and PV cells in the near-field configuration. We find that the near-field effect has a marginal impact on TPX cells with identical bandgaps, which means that the near-field TPX cell in the self-sustaining circuit will not be useful in practice. The insights gained from this work serve as valuable design guidelines for TPX cells operating in the self-sustaining parallel circuit, enabling practical operation without the need for an external battery storage unit.
Author Identification from Song Lyrics
No full textMachine Learning (ML) tools have been used extensively in a wide variety of domains
recently. Due the enormous amount of data being produced, machine learning techniques
are being heavily used to make sense of data & derive meaningful results. Using machine
learning tools, we can turn the data into knowledge.
Music is one of the truest forms of art. Bangladesh has a great history of music with a
great tradition of song writing over centuries. Authorship attribution is the way of
identifying the author from a linguistic corpus.
This paper demonstrates a guideline to identify the author of a Bengali song from the
lyrics of that song using machine learning. This research work presents the first work on
machine learning approach for author attribution from the lyrics of a song. Here six
methods of machine learning are used for the author identification and high accuracies
have been achieved from these methods. It is observed that Naïve Bayes method provides
higher accuracy in comparison with the other methods
Song
No full textAuthor attribution from Rudolph, 240. Printed on yellow paper with black ink. Set to the tune of "Happy land of Canaan". First line "You Rebels come along and listen to my song"
The Singer or the Song? Developments in Performers' Rights from the Perspective of a Cultural Economist
No full textOver the last century, performers gradually acquired statutory protection of their economic and moral
rights. These rights are not copyright in the legal sense but neighboring rights and until recently, they
were mainly remuneration rights that are collectively administered. With the WPPT (WIPO
Performers and Phonograms Treaty), performers now have individual exclusive rights for digital
performances; this leads to the question: what has motivated this change – is it a change in the
perception of the value of performer or a change brought about by the changing technology of copying or,
indeed, a change that reflects different economic costs and benefits? The paper discusses the role of
copyright law as an incentive to performers and asks if the economic role of the performer is so different
from that of the author. The conclusion is that a complex interaction of the legal regulations, economic
conditions and institutional arrangements for administering these new rights will determine the outcome
Freemasons\u27 Song
No full textSong concerning pride in Freemasonryhttps://egrove.olemiss.edu/kgbsides_uk/1560/thumbnail.jp
Northumberland Election Song
No full textA song for a political candidate.https://egrove.olemiss.edu/kgbsides_uk/1899/thumbnail.jp
Song of Haymakers
No full textA song about working in the hayfields during summer.https://egrove.olemiss.edu/kgbsides_uk/1628/thumbnail.jp
Appendix to Esther's Song
No full textNotes - 'Esther's Song' with descriptive entries on friends, associates, and family members (125 pages)Appendi
Age-dependent song changes in a closed-ended vocal learner: elevation of song performance after song crystallization
No full textBirdsong is a sexual signal that serves as an indicator of male quality. There is already abundant evidence that song elaboration reflects early life-history because early developmental stress affects neural development of song control systems, and leaves irreversible adverse effects on song phenotypes. Especially in closed-ended vocal learners, song features crystallized early in life are less subject to changes in adulthood. This is why less attention has been paid to lifelong song changes in closed-ended learners. However, in the eyes of female birds that gain benefits from choosing mates based on male songs, not only past but also current conditions encoded in songs would be meaningful, given that even crystallized songs in closed-ended learners would not be identical in the long term. In this study, we examine within-individual song changes in the Java sparrow Lonchura oryzivora, with the aim of shedding light on the relationship between song and long-term life history. Specifically, we compared song length, tempo, and song complexity measures between the point just after song crystallization and around 1 yr later, and also compared those traits between fathers and sons to clarify the effect of vocal learning. While it is not surprising that song complexity did not differ depending on age or between fathers and sons, we found that song length and tempo increased with age. Follow-up analyses have revealed that frequency bandwidth and peak frequency of song notes also elevated with age. Our results show that song performance related to motor skills can be improved even after song crystallization. We also suggest that song performance in closed-ended vocal learners gives a reliable clue for mate choice by reflecting male quality with aging
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