212 research outputs found
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
Corrigendum to "Biosurfactant mediated synthesis of NiO nanorods" [Materials Letters, Volume 62, Issues 4–5, 2008, pp. 743–746]
No full text1. In the original publication Ashok M. Raichur was not listed as corresponding author.
2. The Acknowledgements (p. 746) of the paper should read as follows:
The authorswould like to acknowledge Mr. Karthik and Dr. Suresha, Indian Institute of Science, Bangalore, India for the assistance in taking the TEM images. Comments and suggestions on nanorod synthesis by Dr. Suresh Babu and Dr. S. Patil, AMPAC, UCF are greatly acknowledged
Further Evaluation of the Modified Affinity Laws for the Prediction of Viscosity Effect on the Pump Head Performance
No full textLectureThe aforementioned abstract was accepted in the ASME Journal of Fluid Engineering and may cause copyright issues. The author wishes to submit this abstract and will get us a manuscript by May 1st if approved by the committee
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Influence of diluent alkyl substitution on the extraction of Am(III) and Eu(III) by a 6,6’-bis(1,2,4-triazin-3-yl)-2,2’-bipyridine ligand dissolved in alkylated cyclohexanone Diluents
No full textSeveral alkylated cyclohexanones were investigated as potential diluents for the selective extraction of Am(III) from Eu(III) from nitric acid solutions by the CyMe4-BTBP ligand. No significant extraction of either of the metal ions was observed for these diluents themselves. In the extractions from 1 M HNO3, 3-methylcyclohexanone and 4-methylcyclohexanone gave comparable results to cyclohexanone whereas in the extractions from 4 M HNO3, 2-methylcyclohexanone, 3-methylcyclohexanone and 4-methylcyclohexanone all gave superior results. For the monomethylated diluents, DAm and SFAm/Eu decreased in the order of alkyl substitution 2 > 4 ~ 3. However, alkyl substitution of cyclohexanone significantly slows down the extraction kinetics compared to cyclohexanone, and the position of alkyl substitution was found to play an important role in the solvents properties. 3-Methylcyclohexanone was identified as the most promising of the diluent
New synthesis of 2,2 '-heteroarylpyrroles from heteroarylchlorocarbenes
No full text2,2'-Pyridyl- and 2,2'-thienylpyrroles containing substituents at the 1- and 3-positions of the pyrrole ring have been prepared from the reaction of heteroarylchlorocarbenes with 1-azabuta-1,3-dienes. Laser flash photolysis of heteroarylchlorocarbene in isooctane in the presence of 1-azabuta-1,3-diene yields an azomethine ylide (lambda=550 nm) as an intermediate. The kinetic parameters for the ylide formation and further 1,5-intramolecular cyclization to the pyrrole ring have been determined. (C) 1999 Elsevier Science Ltd. All rights reserved.PT: J; CR: BAIRD MS, 1990, J CHEM RES M, P946 ENGEL N, 1978, ANGEW CHEM INT EDIT, V17, P676 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 KATRITZKY AR, 1994, SYNTHESIS-STUTTGART, P93 KOROSTOVA SE, 1989, KHIM GETEROTSIKL+, P901 KOTKAR D, 1988, J CHEM SOC CHEM COMM, P917 KOZAKI M, 1996, J ORG CHEM, V61, P3657 LIU MTH, 1994, INT J CHEM KINET, V26, P1179 LUCCHESINI F, 1992, TETRAHEDRON, V48, P9951 MOSS RA, 1987, J AM CHEM SOC, V109, P4341 MOSS RA, 1992, TETRAHEDRON LETT, V33, P1427 NAITOH S, 1986, J CHEM SOC CHEM COMM, P1348 PATIL AO, 1988, CHEM REV, V88, P183 ROMASHIN YN, 1999, CHEM COMMUN 0307, P447 RONCALI J, 1992, CHEM REV, V92, P711 WALTMAN RJ, 1986, CAN J CHEM, V64, P76 ZELIKIN A, 1999, J ORG CHEM, V64, P3379; NR: 17; TC: 11; J9: TETRAHEDRON LETT; PG: 3; GA: 236PXSource type: Electronic(1
Development of Resonance-Based Test System to Measure Lifetime Curves of Dielectric Materials
No full textWith the increasing growth and penetration of power electronic devices in the power system, it is essential to understand the behaviour of insulation materials and systems under the varied signals that are produced with power electronic systems. These signals could be square pulses, sinusoidal or even superimposed. The high-frequency sinusoidal excitation in the range of 50-100kHz is the focus, of this project. The project aims to design a resonance-based test system to measure the lifetime curves of dielectric materials such as oil-impregnated paper and epoxy under high frequencies. The major components of this project are the H-Bridge Circuitry found on the low voltage side and the resonant transformer which is tuned with the test sample to be in resonance. The design techniques and critical factors for the design of gate driver circuits have been provided. Moreover, through simulations in COMSOL Multiphysics and MATLAB along with practical measurements using vector network analyzers the behaviour of the transformer equivalent circuit parameters with changes in geometry is discussed. Through this understanding, the critical parameters to design a test system to obtain the highest gain while in resonance have been highlighted. The final test setup is designed and is used to perform lifetime tests on oil-paper and epoxy samples, both materials exhibited different behaviour during the tests. Due to the high gain of the system, it is very sensitive to changes in the capacitance of the test object and hence a constant voltage is not applied to the oil-paper sample. Therefore the breakdown times cannot be considered for the lifetime curve. Recommendations are provided to improve the test setup. Epoxy showcased a different behaviour, it is observed that the linear voltage gain of the resonance system is lost once partial discharges are initiated, and the voltage across the test sample becomes constant even upon a further increase in the input voltage. Based on these observations recommendations are provided to improve the test setup along with further topics that need to be studied.Electrical Engineering | Electrical Power Engineerin
What do Circular Strategies Mean for Current HVAC Systems in Utility Buildings?: An Exploratory Research
No full textThis research extensively examines the pivotal shift toward circularity within the European construction and building sector, with a specific emphasis on HVAC systems in utility buildings. It commences by underscoring the pressing urgency precipitated by the Paris Agreement of 2015 and subsequent climate objectives, necessitating reductions in greenhouse gas emissions and resource utilization. The construction and building sector's notable contributions to energy consumption, waste production, and material extraction highlight the imperative to address circularity within this industry.The report delves deeply into the notion of the circular economy (CE), emphasizing its potential to disassociate economic growth from resource depletion and waste generation. While acknowledging the growing scholarly and corporate interest in CE, exemplified by industry giants such as Philips and IKEA, this study highlights the limited practical application of circular principles, particularly within the HVAC systems sector.Recognizing the multifaceted and varying interpretations of circularity, the report seeks to demystify the concept by conducting a thorough literature review and interviews. Through a thematic analysis, it identifies existing challenges, proposes potential solutions, and evaluates the feasibility of implementing circular strategies for HVAC systems. Key findings encompass project-specific considerations, the influence of location and climate, and the imperative need for legislative reforms to expedite the transition.Ultimately, the research provides a valuable starting point for MEP consultants, equipping them with a pragmatic decision support framework and a categorized repertoire of circular strategies. It encourages industry professionals to embrace circularity in HVAC design, bridging knowledge gaps and promoting sustainable practices. While acknowledging the study's limitations, including its qualitative nature and potential for bias, this study calls for future research to validate the framework through real-world cases, expand performance evaluation criteria, and advocate for policy reforms across the broader built environment. In summary, this study constitutes a vital stride toward fostering circularity and sustainability within the construction and HVAC sectors.Civil Engineering | Construction Management and Engineerin
PIV Experimental Comparison of Vertical Axis Wind Turbine Wake with Theoretical Models
No full textVertical Axis Wind Turbine (VAWT) operation is characterized by complex and unsteady three-dimensional fluid dynamics, which presents considerable challenges. One of the crucial points to understand is the complex interaction between rotor, inflow, and wake systems. If we can demonstrate its effectiveness in the complex flow/inflow conditions, will be of great importance. To investigate the wake/wind aerodynamics validate state-of-the-art VAWT wake models, a high ¬fidelity experimental measurement in the domain of VAWT wakes is needed. Computational fluid dynamics (CFD) models for complex wind interactions are far from being feasible. These models are highly time-devouring and computationally expensive, and their cost prohibits the simulation of complex flow configurations. This is usually overcome through the implementation of simple and computationally inexpensive analytical wake models, where the flow conditions are solved through simple analytic expressions and only over specific points of interest. The work aims to realize and validate a simple and efficient analytical wake model (Abkar, 2019 [2]), (Bastankhah & Porté¬Agel, 2014 [7]) for prediction of the wind velocity profile downwind of a VAWT turbine: The best by comparing the modeling results with a set of particle image velocimetry (PIV) measurements of the wakes of an in-house designed VAWT are used as a high-fidelity reference. The present work evaluates and quantifies the influence of the wake deflection produced by the pitch angles of the blades on the scaled VAWT turbine. It reproduces the main phenomena involved in the flow pattern and identifies the general structure of the resulting wake that occurs: under the influence of pitching the blades on the upstream turbine. The configuration consists of a VAWT aligned in the direction of the incoming flow: With a class of cases for different configurations of the turbine are studied for example ¬ deflection of wake through zero pitch, positive 10 degrees pitch, Negative 10 degrees pitch angles (Mendoza et al, 2019 [32]). The available power distribution over other hypothetical downwind turbines due to the influence of wake deflection by the upstream turbine is studied and reported. These interactions are measured with the help of large ¬scale PIV experiments in OJF, TU Delft. Also, an efficacious force balance system for the VAWT rotor is studied, designed, and fabricated (in-house) to calculate the accurate lift and drag forces on the VAWT structure. The stereo particle image velocimetry results are compared with two theoretical works Jensen wake model, [21] and Gaussian-based wake model Abkar [2] and CFD simulations by Huang et al [18]. The study shows a wake shift towards the windward side (cross-flow width), Negative¬ Y direction. For all the pitch cases, maximum for the positive pitch angle and least for a negative pitch angle. The wake shift in the negative ¬Y direction can be caused by the blade rotation, with the clockwise rotation of the VAWT rotor, and the rear blade turning into the incoming flow of wind. The theoretical models especially the Gaussian-based wake model represent the wake deficit in close agreement to the experimental results but fails to account for wake shift and change in wake structure. The CFD simulations reproduce the 3D wake structures consistent with the experiment results but show an early recovery in the wake. The wake recovery with downwind available power is found higher with a positive pitch angle and least with the negative pitch. A study of in-plane velocity vectors indicates crosswind force introducing crosswind momentum to the flow and as a result would give rise to the CVPs, also according to a study by Rolin F, Porte-Agel [38]. The theoretical models do not account for any of these structural changes in wake and the deflections in them. Furthermore, the suitability of these experimental references are used to verify the CFD simulations and analytical models’ range of the fidelityElectrical Engineering | Sustainable Energy Technolog
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