1,356,920 research outputs found
Preliminary Design Of A Nano Gas Turbine For Portable Power Generation” di R. Capata e E. Sciubba. ,
No full textMeasurement of the electron reconstruction efficiency at LHCb
No full textThe single electron track-reconstruction efficiency is calibrated using a sample corresponding to 1.3 fb−1 of pp collision data recorded with the LHCb detector in 2017. This measurement exploits B
+ → J/ψ(e
+
e
−
)K
+ decays, where one of the electrons is fully reconstructed
and paired with the kaon, while the other electron is reconstructed using only the information of
the vertex detector. Despite this partial reconstruction, kinematic and geometric constraints allow
the B meson mass to be reconstructed and the signal to be well separated from backgrounds. This
in turn allows the electron reconstruction efficiency to be measured by matching the partial track
segment found in the vertex detector to tracks found by LHCb’s regular reconstruction algorithms.
The agreement between data and simulation is evaluated, and corrections are derived for simulated electrons in bins of kinematics. These correction factors allow LHCb to measure branching
fractions involving single electrons with a systematic uncertainty below 1%
A revised calculation of the econometric factors α- and β for the Extended Exergy Accounting method
No full textExtended Exergy Accounting (" EEA" ) is a method to compute the space- and time integral of the primary exergy required to produce a good or a service: the extended exergy of a commodity measures its " embodied exergy" , including externalities (Labour, Capital and Environmental Costa). A crucial point of the method is the calculation of two econometric coefficients, commonly referred to as " α" and " β" ,used to calculate the extended exergy equivalents of Labour and Capital respectively. In previous applications of the EEA method, these coefficients have been assigned approximate values estimated on the basis of global system considerations. In this paper, a novel procedure is described that leads to the calculation of " exact" values of both econometric coefficients, based on detailed exergy- and monetary balances of the Society to which the EEA is applied. It is shown that both α and β depend in a non-trivial way from the consumption patterns, the technological level and the life- and socio-economic standards of each Country. It is also shown that the values are substantially different for developed (OECD) and underdeveloped Countries, and representative samples of values are calculated and critically analysed. On the basis of these new model coefficients, the specific exergy equivalents of Labour (ee L) and of Capital (ee K) are calculated, and shown to differ from the values used in previous EEA calculations. © 2010 Elsevier B.V
A Critical Reassessment of the Hess–Murray Law
No full textThe Hess–Murray law is a correlation between the radii of successive branchings in bi/trifurcated vessels in biological tissues. First proposed by the Swiss physiologist and Nobel laureate Walter Rudolf Hess in his 1914 doctoral thesis and published in 1917, the law was “rediscovered” by the American physiologist Cecil Dunmore Murray in 1926. The law is based on the assumption that blood or lymph circulation in living organisms is governed by a “work minimization” principle that—under a certain set of specified conditions—leads to an “optimal branching ratio” of r i + 1 r i = 1 2 3 = 0.7937 . This “cubic root of 2” correlation underwent extensive theoretical and experimental reassessment in the second half of the 20th century, and the results indicate that—under a well-defined series of conditions—the law is sufficiently accurate for the smallest vessels (r of the order of fractions of millimeter) but fails for the larger ones; moreover, it cannot be successfully extended to turbulent flows. Recent comparisons with numerical investigations of branched flows led to similar conclusions. More recently, the Hess–Murray law came back into the limelight when it was taken as a founding paradigm of the Constructal Law, a theory that employs physical intuition and mathematical reasoning to derive “optimal paths” for the transport of matter and energy between a source and a sink, regardless of the mode of transportation (continuous, like in convection and conduction, or discrete, like in the transportation of goods and people). This paper examines the foundation of the law and argues that both for natural flows and for engineering designs, a minimization of the irreversibility under physically sound boundary conditions leads to somewhat different results. It is also shown that, in the light of an exergy-based resource analysis, an amended version of the Hess–Murray law may still hold an important position in engineering and biological sciences
A Thermodynamically Correct Treatment of Externalities with an Exergy-Based Numeraire
No full textThe concept of “sustainable development” implies that the environmental externalities unavoidably generated by human activities be reduced to a minimum: In fact, the very definition of “sustainability” leads—as it will be briefly discussed in the paper—to a physically measurable upper limit for untreated discharges. Since the current state of affairs on Earth is far from being sustainable, any proposal for a future scenario that is not substantiated by an accurate assessment of the effects of the environmental externalities is devoid of real sense and ought not to be pursued. The present paper illustrates the application of Extended Exergy Accounting (EEA) to the quantification of such externalities. The exergy flow diagrams of EEA include non-material and non-energetic production factors like labor, and capital and environmental remediation costs, providing a quantitative measure of the amount of primary resources that are cumulatively used in the production of a good or service, and it is shown to provide a wealth of quantitative information to energy managers and planners
A Critical Interpretation and Quantitative Extension of the Sama-Szargut Second Law Rules in an Extended Exergy Perspective
No full textTwenty-five years ago, Gaggioli, Sama and Qian published a series of 10 “second law guidelines” for design and process engineers, nicknamed at that time “the Gaggioli-Sama rules”. These guidelines, some of them previously published by Sama between 1980 and 1983, are a compilation of “second law errors” to avoid in the design of energy conversion systems. The list was rearranged several times, until a revised version containing 21 rules was published by Sama and Szargut in 1995. Ever since, these guidelines came to be known as “the Sama-Szargut rules”. The rules are a series of well-formulated and insightful suggestions that reflect a thermodynamicist’s idea that the “best design” is the one that minimizes the overall irreversibility in a process or plant, under the prescribed technological constraints. Characteristically, the concept of “optimal system” is completely absent, the emphasis being on the extensive inclusion of second law reasoning into design decisions. A critical analysis of the rules would suggest that all of them be routinely implemented both in new designs and most important in retrofit projects. A survey of some of the current most common energy conversion installations shows that, quite on the contrary, most of the rules are disregarded in practical applications. This paper argues that the reason for this incongruency is the neglection in the engineering design decision of the real cost of installation, operation and decommissioning of a plant, and proposes a rephrasing of the rules in an extended exergy perspective: if the production cost, including the externalities, is measured in units of equivalent primary exergy, the Sama-Szargut rules can be directly interpreted in this sense, and abidance by the rules results in the reduction of the resource cost for any given objective
Paradigms of refuse: waste abjection and rejection in contemporary Italian literature and cinema
No full text“Paradigms of Refuse” explores Italy and the Mediterranean as landscapes of crisis, sites where environmental threats, social inequalities, and geopolitical turmoil converge. These landscapes are increasingly being transformed into dumping sites where the material as well as the human excess of our modern societies are discarded. In this study, I propose the concept of refuse– which refers both to the matter thrown away or rejected as worthless, as well as to the acts of refusing, declining and rejecting – as a theoretical tool to approach different dimensions of exclusion and exploitation with reference to both human beings and the natural environment. “Paradigms of Refuse” moves across these different meanings of refuse in order to offer an account of environmental and social unrest in contemporary Italy. By mapping the social as well as the material figuration of the refuse through close analysis of contemporary Italian literature and cinema, I expose not only the detrimental impact of the human over the environment, but also the ways in which the human/non-human remnants of our consumer culture can be approached in transformative ways as instruments of subversion. Refuse can become a tool to foster awareness, to shake consciences, to create discomfort and blur divides between human and non-human, nature and culture, the self and the other.
Through refuse, I address the condition of the marginalized strata of the Italian society who are refused as the collateral waste of modernity while also refusing to conform to normalizing paradigms of inclusion: examples of these marginalized groups include migrants, the economically underprivileged, Roma communities, prostitutes. The employment of refuse as a theoretical tool allows to approach with coherence issues otherwise confined to distinct analytical paths, from the smuggling and disposal of waste, both human and non-human, to the insertion of the migrant, or other marginalized strata of Italian society, into the realm of worthless waste, with the consequent abjectification of the human (gendered) body.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2019-12-01The student, Jessica Sciubba, accepted the attached license on 2017-12-01 at 14:50.The student, Jessica Sciubba, submitted this Dissertation for approval on 2017-12-01 at 14:59.This Dissertation was approved for publication on 2017-12-07 at 08:03.DSpace SAF Submission Ingestion Package generated from Vireo submission #11804 on 2018-03-13 at 09:56:38Made available in DSpace on 2018-03-13T15:25:20Z (GMT). No. of bitstreams: 3
SCIUBBA-DISSERTATION-2017.pdf: 3514042 bytes, checksum: 343deb6af3e17be7a9017526296025dc (MD5)
LICENSE.txt: 4212 bytes, checksum: bf28b051f296b02141b295195a8ac9a5 (MD5)
Sciubba copyright letter.pdf: 144815 bytes, checksum: c91c2407fad337a92c162ab007005a85 (MD5)
Previous issue date: 2017-12-07Embargo set by: Seth Robbins for item 105182
Lift date: 2020-03-13T15:25:40Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 105182
Lift date: 2020-03-13T15:28:52Z
Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD systemU of I Only Restriction Lifted for Item 105182 on 2020-03-14T09:15:12Z
Design and Performance Prediction of a Ultra-Micro Gas Turbine for Portable Power Generation
No full textIn the last decades, the enormous growth in portable electronics applications has stimulated research in lightweight and reliable power sources. In this technological niche, the idea of developing miniaturized turbomachinery to serve as portable power sources is attractive, especially in view of the much higher power density of a small turbogas generator in comparison with conventional chemical batteries. The potential social impact of an eventual commercialization of such "nano-devices" is enormous, but the technological and phenomenological complexity of the design and manufacturing of ultra-small machines (with a rotor diameter of the order of 1 cm) poses difficult problems, because some of the well-established design procedures for large and medium scale machines do not seem to be applicable as such at these extremely reduced scales. In this work the design and performance of a miniaturized gas turbine with a tip diameter of about 10 mm is examined from a thermo-fluiddynamic point of view. An extensive series of CFD simulations allows for the quantification of the losses at the resulting low Reynolds numbers (∼4600 in the stator and ∼1500 in the rotor) on the single-curvature geometry imposed by manufacturing constraints. The geometry of the blades is "optimized" on the basis of an entropy generation rate analysis, and the capabilities and limitations of conventional design strategies are assessed. Copyright © 2007 by ASME
From Engineering Economics to Extended Exergy Accounting: a possible path from “monetary” to “resource-based” costing
No full text- …
