4,679 research outputs found
Second-Order Functions and Theorems in ACL2
SOFT ('Second-Order Functions and Theorems') is a tool to mimic second-order
functions and theorems in the first-order logic of ACL2. Second-order functions
are mimicked by first-order functions that reference explicitly designated
uninterpreted functions that mimic function variables. First-order theorems
over these second-order functions mimic second-order theorems universally
quantified over function variables. Instances of second-order functions and
theorems are systematically generated by replacing function variables with
functions. SOFT can be used to carry out program refinement inside ACL2, by
constructing a sequence of increasingly stronger second-order predicates over
one or more target functions: the sequence starts with a predicate that
specifies requirements for the target functions, and ends with a predicate that
provides executable definitions for the target functions.Comment: In Proceedings ACL2 2015, arXiv:1509.0552
Monitoring bank performance in the presence of risk
This paper proposes a managerial control tool
that integrates risk in efficiency measures. Building on
existing efficiency specifications, our proposal reflects the
real banking technology and accurately models the relationship
between desirable and undesirable outputs. Specifically,
the undesirable output is defined as nonperforming
loans to capture credit risk, and is linked only
to the relevant dimension of the output set. We empirically
illustrate how our efficiency measure functions for managerial
control purposes. The application considers a unique
dataset of Costa Rican banks during 1998–2012. Results’
implications are mostly discussed at bank-level, and their
interpretations are enhanced by using accounting ratios.
We also show the usefulness of our tool for corporate
governance by examining performance changes around
executive turnover. Our findings confirm that appointing
CEOs from outside the bank is associated with significantly
higher performance ex post executive turnover, thus suggesting
the potential benefits of new organisational
practices.Peer ReviewedPostprint (author’s final draft
The Herschel PACS photometer calibration - A time dependent flux calibration for the PACS chopped point-source photometry AOT mode
We present a flux calibration scheme for the PACS chopped point-source
photometry observing mode based on the photometry of five stellar standard
sources. This mode was used for science observations only early in the mission.
Later, it was only used for pointing and flux calibration measurements. Its
calibration turns this type of observation into fully validated data products
in the Herschel Science Archive. Systematic differences in calibration with
regard to the principal photometer observation mode, the scan map, are derived
and amount to 5-6%. An empirical method to calibrate out an apparent response
drift during the first 300 Operational Days is presented. The relative
photometric calibration accuracy (repeatability) is as good as 1% in the blue
and green band and up to 5% in the red band. Like for the scan map mode,
inconsistencies among the stellar calibration models become visible and amount
to 2% for the five standard stars used. The absolute calibration accuracy is
therefore mainly limited by the model uncertainty, which is 5% for all three
bands.Comment: 20 pages, 7 pages of appendix, 11 figures, accepted to appear in
Experimental Astronomy, Special Issue for Herschel Calibrations based on the
"Herschel Calibration Workshop: Only the Best Data Products for the Legacy
Archive", held at ESAC, 25 - 27 March 2013,
http://herschel.esac.esa.int/CalibrationWorkshop5.shtm
Verification of Agent-Based Artifact Systems
Artifact systems are a novel paradigm for specifying and implementing
business processes described in terms of interacting modules called artifacts.
Artifacts consist of data and lifecycles, accounting respectively for the
relational structure of the artifacts' states and their possible evolutions
over time. In this paper we put forward artifact-centric multi-agent systems, a
novel formalisation of artifact systems in the context of multi-agent systems
operating on them. Differently from the usual process-based models of services,
the semantics we give explicitly accounts for the data structures on which
artifact systems are defined. We study the model checking problem for
artifact-centric multi-agent systems against specifications written in a
quantified version of temporal-epistemic logic expressing the knowledge of the
agents in the exchange. We begin by noting that the problem is undecidable in
general. We then identify two noteworthy restrictions, one syntactical and one
semantical, that enable us to find bisimilar finite abstractions and therefore
reduce the model checking problem to the instance on finite models. Under these
assumptions we show that the model checking problem for these systems is
EXPSPACE-complete. We then introduce artifact-centric programs, compact and
declarative representations of the programs governing both the artifact system
and the agents. We show that, while these in principle generate infinite-state
systems, under natural conditions their verification problem can be solved on
finite abstractions that can be effectively computed from the programs. Finally
we exemplify the theoretical results of the paper through a mainstream
procurement scenario from the artifact systems literature
Assessment of construction cost reduction of nearly zero energy dwellings in a life cycle perspective
Concerning Nearly Zero Energy Buildings, it is important to guarantee energy efficiency, thermal comfort and indoor environmental quality, while keeping construction and operational costs low. In this framework, this paper explores the efficacy of applying different scenarios, for reducing construction costs of new nearly zero energy multi-family houses in a life cycle perspective. Conversely to the standard cost-optimal approach, a real Italian case study building was chosen. Alternative and unconventional combinations of solutions for envelope and technical systems were adopted. Calculations were performed in two Italian cities (Rome and Turin). Three types of analysis were developed thermal comfort, energy performance and financial calculation. Results of the thermal analysis show that the installation of active cooling to prevent summer overheating can be avoided by applying low-cost passive strategies. All the proposed low-cost scenarios (4 alternative scenarios in Rome and 5 in Turin)reached the highest grade of energy performance, with a reduction of the non-renewable primary energy consumption up to 46% compared to the base case in Rome and 18% in Turin. From the economic perspective, all the scenarios in the two climate zones allow both reductions in the construction costs, up to 26% in Rome and 15% in Turin, and a Net Present Value after 50 years up to 163 €/m2 in Rome and 158 €/m2 in Turin
Study of Application of L.E.D. Lighting System in Mines
The work done on the project contains field observations for lighting in underground and open-cast mines showing general requirements of lighting and sources of lighting. Regulations related to mine lighting are briefly enumerated. Illumination and cost comparison of different lighting sources is done showing advantages of Light emitting diode (LED) system of lighting over conventional system. Iluminance Measuring techniques and instrumentation for conducting illumination survey are briefly enumerated giving brief description of Metravi 1332 luxmeter. Comparison between different features of CFL, LED and Incandescent bulbs of application of LED system of lighting for effective energy conservation, better illumination, lower cost per day, etc..
Illumination levels at different working places in Tirap open cast coal mine, NEC, a subsidiary of Coal India limited are illustrated. And a study is done showing power savings and cost effectiveness if L.E.D. lighting system is used against the conventional lighting system used at Tirap OCP, NEC. Power saving was found to be about 73.487 % and a significant amount of cost saving was also shown. A critical comparison emphasizing the use of L.E.D. cap-lamp over conventional cap-lamp is shown with reference to experimental studies done at GDK-10 incline, SCCL. The LED cap lamp produced an illumination of 38 lux at a distance of 4 m from the source as compared to the 21 lux produced by conventional cap lamp. Thus, it was found that LED lighting system had more advantages over conventional lighting system
Verification of Imperative Programs by Constraint Logic Program Transformation
We present a method for verifying partial correctness properties of
imperative programs that manipulate integers and arrays by using techniques
based on the transformation of constraint logic programs (CLP). We use CLP as a
metalanguage for representing imperative programs, their executions, and their
properties. First, we encode the correctness of an imperative program, say
prog, as the negation of a predicate 'incorrect' defined by a CLP program T. By
construction, 'incorrect' holds in the least model of T if and only if the
execution of prog from an initial configuration eventually halts in an error
configuration. Then, we apply to program T a sequence of transformations that
preserve its least model semantics. These transformations are based on
well-known transformation rules, such as unfolding and folding, guided by
suitable transformation strategies, such as specialization and generalization.
The objective of the transformations is to derive a new CLP program TransfT
where the predicate 'incorrect' is defined either by (i) the fact 'incorrect.'
(and in this case prog is not correct), or by (ii) the empty set of clauses
(and in this case prog is correct). In the case where we derive a CLP program
such that neither (i) nor (ii) holds, we iterate the transformation. Since the
problem is undecidable, this process may not terminate. We show through
examples that our method can be applied in a rather systematic way, and is
amenable to automation by transferring to the field of program verification
many techniques developed in the field of program transformation.Comment: In Proceedings Festschrift for Dave Schmidt, arXiv:1309.455
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