4,036 research outputs found
A 360 Degree View Of Selecting A Lubricant For My New Low GWP Refrigerant
The advent of environmentally friendly refrigerants and the global drive for higher efficiency is bringing change to our industry. A review of current HFC refrigerants and their lubricant choices over a range of evaporator temperatures will be summarized and compared to the numerous low GWP refrigerant replacements and associated lubricant considerations. The paper details a methodology for matching a refrigerant and a lubricant over a variety of low GWP refrigerant options. The current challenges in meeting miscibility, solubility, discharge temperature and working viscosity targets will be discussed and options presented. As the industry develops and implements both interim, lower GWP alternatives and long-term low or ultra-low GWP refrigerant options, in some cases the door has opened for development of new or optimized lubricant chemistries which are both compatible with the new refrigerants and also maintain or improve equipment performance and reliability. For example, CPI recognizes that the solubility characteristics of the low GWP refrigerants in many cases are different than the incumbent HFC refrigerants. CPI has investigated the solubility characteristics of new refrigerants and has developed innovative lubricant formulations to control solubility to minimize the need for equipment hardware or operating changes. While low GWP refrigerants are environmentally friendly with a shorter atmospheric life, in some cases either the refrigerants or the equipment operating conditions will bring about system chemistry concerns that didn’t exist with the stable HFC refrigerants such as R-134a. CPI will discuss methods to monitor for lubricant and refrigerant stability in a refrigeration system, and options to mitigate chemical stability concerns. The information shared in this presentation will provide a 360-degree view of the important aspects of matching a refrigerant to a lubricant for successful and reliable equipment operation
Risky choices in strategic environments: An experimental investigation of a real options game
Managers frequently make decisions under conditions of fundamental uncertainty due the stochastic nature of the outcomes and competitive rivalry. In this study, we experimentally test a theoretical model under fundamental uncertainty and competitive rivalry by designing a sequential interaction game between two players. The first mover can decide either to choose a sure outcome that assigns a risky outcome to the second mover or to pass the decision to the second mover. If the second player gets the chance to decide, she can choose between a sure outcome, conditioned by the assignment of a risky payoff to the first mover, or the sharing of the risky outcome with the first mover. We then introduce the following experimental treatments: (i) relegating second-mover participants to a purely passive role and substituting them with a random device (absence of strategic uncertainty - that is, when the source of uncertainty is a human subject); (ii) providing information about the behaviour of second-mover counterparts; and (iii) completely removing the second-mover participant.We find that decision makers are sensitive to the presence or absence of strategic uncertainty; indeed, in the presence of strategic uncertainty, first movers more often diverge from the behaviour predicted by the model. Given our experimental results, the theoretical model needs to be revisited. The standard model of monetary payoff-maximizing agents should be substituted by one of decision makers who maximize a utility function which includes the psychological cost induced by strategic uncertainty. (C) 2019 Published by Elsevier B.V
The management of dental practices in the post-covid 19 era: An economic and operational perspective
Background: In order to protect dental teams and their patients during the COVID-19 pandemic, dentists have had to adopt several measures (operating and post-operating procedures) which may increase the total treatment time and costs relating to individual protective measures. This paper will propose a thorough analysis of operating dentistry procedures, comparing the economic performance of the activity in a dental surgery before and after the adoption of these protective measures, which are required to contain the risk of SARS-COV-2 infections. Methods: The economic analysis is articulated in three approaches. Firstly, it assesses a reduction in markup by maintaining current charges (A); alternatively, it suggests revised charges to adopt in order to maintain unvaried levels of markup (B). And the third Approach (C) examines available dental treatments, highlighting how to profitably combine treatment volumes to reduce markup loss or a restricted increase in dental charges. Results: Maintaining dental charges could cause a loss in markup, even rising to 200% (A); attempting to maintain unvaried levels of markup will result in an increase in dental charges, even at 100% (B); and varying the volumes of the single dental treatments on offer (increasing those which current research indicates as the most profitable) could mitigate the economic impact of the measures to prevent the transmission of SARS-COV-2 (C). Conclusions: The authors of this paper provide managerial insights which can assist the dentist-entrepreneur to become aware of the boundaries of the economic consequences of governmental measures in containing the virus infection
The Baxter Q Operator of Critical Dense Polymers
We consider critical dense polymers , corresponding to a
logarithmic conformal field theory with central charge . An elegant
decomposition of the Baxter operator is obtained in terms of a finite
number of lattice integrals of motion. All local, non local and dual non local
involutive charges are introduced directly on the lattice and their continuum
limit is found to agree with the expressions predicted by conformal field
theory. A highly non trivial operator is introduced on the lattice
taking values in the Temperley Lieb Algebra. This function provides a
lattice discretization of the analogous function introduced by Bazhanov,
Lukyanov and Zamolodchikov. It is also observed how the eigenvalues of the
operator reproduce the well known spectral determinant for the harmonic
oscillator in the continuum scaling limit.Comment: improved version, accepted for publishing on JSTA
On the Integrable Structure of the Ising Model
Starting from the lattice realization of the Ising model defined on a
strip with integrable boundary conditions, the exact spectrum (including
excited states) of all the local integrals of motion is derived in the
continuum limit by means of TBA techniques. It is also possible to follow the
massive flow of this spectrum between the UV conformal fixed point and
the massive IR theory. The UV expression of the eigenstates of such integrals
of motion in terms of Virasoro modes is found to have only rational
coefficients and their fermionic representation turns out to be simply related
to the quantum numbers describing the spectrum.Comment: 18 pages, no figure
Integrals of Motion for Critical Dense Polymers and Symplectic Fermions
We consider critical dense polymers . We obtain for this model
the eigenvalues of the local integrals of motion of the underlying Conformal
Field Theory by means of Thermodynamic Bethe Ansatz. We give a detailed
description of the relation between this model and Symplectic Fermions
including the indecomposable structure of the transfer matrix. Integrals of
motion are defined directly on the lattice in terms of the Temperley Lieb
Algebra and their eigenvalues are obtained and expressed as an infinite sum of
the eigenvalues of the continuum integrals of motion. An elegant decomposition
of the transfer matrix in terms of a finite number of lattice integrals of
motion is obtained thus providing a reason for their introduction.Comment: 53 pages, version accepted for publishing on JSTA
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