scholarly journals Soundness, idempotence and commutativity of set-sharing

2002 ◽  
Vol 2 (2) ◽  
pp. 155-201 ◽  
Author(s):  
PATRICIA M. HILL ◽  
ROBERTO BAGNARA ◽  
ENEA ZAFFANELLA
Keyword(s):  
Logic Programming ◽  
Abstract Interpretation ◽  
Theoretical Study ◽  
Data Flow ◽  
Practical Work ◽  
Mathematical Framework ◽  
Generic Properties ◽  
Set Sharing ◽  
Theoretical Results

It is important that practical data-flow analyzers are backed by reliably proven theoretical results. Abstract interpretation provides a sound mathematical framework and necessary generic properties for an abstract domain to be well-defined and sound with respect to the concrete semantics. In logic programming, the abstract domain Sharing is a standard choice for sharing analysis for both practical work and further theoretical study. In spite of this, we found that there were no satisfactory proofs for the key properties of commutativity and idempotence that are essential for Sharing to be well-defined and that published statements of the soundness of Sharing assume the occurs-check. This paper provides a generalization of the abstraction function for Sharing that can be applied to any language, with or without the occurs-check. Results for soundness, idempotence and commutativity for abstract unification using this abstraction function are proven.

Explanation of the Influence of Inflow Air Content on the Lift of Cavitating Hydrofoils

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Eduard Amromin
Keyword(s):  
Experimental Data ◽  
Theoretical Study ◽  
Lift Coefficient ◽  
Cavity Surface ◽  
Air Bubbles ◽  
Incoming Flow ◽  
Fluid Density ◽  
Air Content ◽  
Theoretical Results ◽  
Good Agreement

According to several known experiments, an increase of the incoming flow air content can increase the hydrofoil lift coefficient. The presented theoretical study shows that such increase is associated with the decrease of the fluid density at the cavity surface. This decrease is caused by entrainment of air bubbles to the cavity from the surrounding flow. The theoretical results based on such explanation are in a good agreement with the earlier published experimental data for NACA0015.

scholarly journals Theoretical Study of the Reaction of Formation of Some Free Phosphines by Stereoselective Hydrophosphination through DFT Method

2018 ◽  
pp. 1-10
Author(s):  
Kouadio Valery Bohoussou ◽  
Anoubilé Bénié ◽  
Mamadou Guy-Richard Koné ◽  
N’guessan Yao Silvère Diki ◽  
Kafoumba Bamba ◽  
...  
Keyword(s):  
Theoretical Study ◽  
Chemical Reactivity ◽  
Dft Method ◽  
Trans Form ◽  
Dft Methods ◽  
Activation Barriers ◽  
Reactivity Descriptors ◽  
Chemical Reactivity Descriptors ◽  
Theoretical Results ◽  
Cis Isomer

In this work the formation of vinylphosphines was studied through the hydrophosphination reaction. The study aims to rationalize the stereoselectivity of these compounds using quantum DFT methods. This theoretical study of chemical reactivity was conducted at B3LYP/6-311 + G (d, p) level. Global chemical reactivity descriptors, stationary point energies and activation barriers were examined to foretell the relative stability of the stereoisomers formed. The various results obtained have revealed that the addition of arylphosphine to dihalogenoacetylene is stereospecific. The Trans form of vinylphosphines is more stable than the Cis form, when the substituent on phosphorus generates less or no π-conjugations. On the other hand, the Cis isomer is predominant when the aryl radical favors more π-conjugations. The theoretical results obtained are in agreement with the experimental results.

Investigation of Endochronic Constitutive Equation Subject to Plastic Strain-Controlled Axial-Torsional Deformation

1986 ◽  
Vol 108 (3) ◽  
pp. 262-269 ◽  
Author(s):  
Han C. Wu ◽  
J. C. Yao ◽  
S. C. Chu
Keyword(s):  
Plastic Strain ◽  
Theoretical Study ◽  
Test System ◽  
Torsional Deformation ◽  
Endochronic Theory ◽  
Phase Path ◽  
Strain Paths ◽  
Theoretical Results ◽  
Material Test System ◽  
Good Agreement

Plastic-strain controlled test is investigated both experimentally and theoretically. The plastic-strain control is feasible by means of computer-aided material test system. Theoretical study is made by use of the modified endochronic theory in which plastic strain is employed to define intrinsic time. Three in-phase plastic-strain paths (a pure axial path, a pure torsional path and an axial-torsional in-phase path) and two out-of-phase plastic-strain paths (small and large perturbations from the axial-torsional in-phase path) are studied. It is shown that the theory and experiment have good agreement. Furthermore, both experimental and theoretical results show that strain-hardening is enhanced by out-of-phase loading.

A theoretical study of the structure and dynamics of amorphous Fe

1992 ◽  
Vol 70 (8) ◽  
pp. 627-630 ◽  
Author(s):  
Neelam Gupta ◽  
Kamal C. Jain ◽  
Arun Pratap ◽  
N. S. Saxena
Keyword(s):  
Transition Metal ◽  
Theoretical Study ◽  
Liquid Metals ◽  
Pair Potential ◽  
Good Qualitative Agreement ◽  
Isothermal Bulk Modulus ◽  
Structure And Dynamics ◽  
Pair Potentials ◽  
Molecular Dynamics Results ◽  
Theoretical Results

The extended theory of transition-metal potential, which includes the transition-metal d states, is used to obtain the effective interatomic interactions in terms of pair potential for amorphous Fe. Pair potential for amorphous Fe is also computed using a simple approach for liquid metals given by de-Angelis and March. We employ the so obtained pair potentials to calculate the longitudinal- and transverse-phonon eigenfrequencies using the theory of phonons in amorphous solids. The results for the phonon eigenfrequencies obtained from these potentials are in good qualitative agreement with the molecular-dynamics results as well as with the theoretical results of Bhatia and Singh. Computation of the Debye temperature and the isothermal bulk modulus also shows a close agreement with other results.

Using the Reflectometric Technique for Monitoring the Boiling Flow Dynamics in a Once Through Steam Generator

2014 ◽  
Author(s):  
Francesco Cordella ◽  
Mauro Cappelli ◽  
Massimo Sepielli
Keyword(s):  
Control Systems ◽  
Steam Generator ◽  
Theoretical Study ◽  
Systems Design ◽  
Correct Choice ◽  
Flow Dynamics ◽  
Nuclear Facilities ◽  
Boiling Flow ◽  
Control Systems Design ◽  
Theoretical Results

In control systems design for nuclear facilities, the correct choice for sensors, transducers and actuators is not an easy task when different options must be evaluated. In particular, for a Once Through Steam Generator (OTSG), the control of its boiling flow dynamics is usually performed with sensors that may be slow in response, must be placed all through the zone of interest (or need heavy mechanical modifications) and may not distinguish correctly when the liquid/steam interface is not so well defined at high temperatures and pressures. In this paper, a theoretical study about a reflectometric technique applied to an OTSG is proposed. This technique can be used also for the liquid/steam levels monitoring of the boiling flow. The overall behaviour of the variables of interest and the first theoretical results show the benefits of such an innovative approach.

scholarly journals Abstract interpretation of temporal concurrent constraint programs

2014 ◽  
Vol 15 (3) ◽  
pp. 312-357 ◽  
Author(s):  
MORENO FALASCHI ◽  
CARLOS OLARTE ◽  
CATUSCIA PALAMIDESSI
Keyword(s):  
Abstract Interpretation ◽  
Data Flow ◽  
Reactive Systems ◽  
Security Protocols ◽  
Denotational Semantics ◽  
Security Protocol ◽  
Mobile Systems ◽  
Abstract Domains ◽  
Concurrent Constraint Programming ◽  
Abstract Semantics

AbstractTimed Concurrent Constraint Programming (tcc) is a declarative model for concurrency offering a logic for specifying reactive systems, i.e., systems that continuously interact with the environment. The universaltccformalism (utcc) is an extension oftccwith the ability to express mobility. Here mobility is understood as communication of private names as typically done for mobile systems and security protocols. In this paper we consider the denotational semantics fortcc, and extend it to a “collecting” semantics forutccbased on closure operators over sequences of constraints. Relying on this semantics, we formalize a general framework for data flow analyses oftccandutccprograms by abstract interpretation techniques. The concrete and abstract semantics that we propose are compositional, thus allowing us to reduce the complexity of data flow analyses. We show that our method is sound and parametric with respect to the abstract domain. Thus, different analyses can be performed by instantiating the framework. We illustrate how it is possible to reuse abstract domains previously defined for logic programming to perform, for instance, a groundness analysis fortccprograms. We show the applicability of this analysis in the context of reactive systems. Furthermore, we also make use of the abstract semantics to exhibit a secrecy flaw in a security protocol. We also show how it is possible to make an analysis which may show thattccprograms are suspension-free. This can be useful for several purposes, such as for optimizing compilation or for debugging.

scholarly journals Optimality in goal-dependent analysis of Sharing

2009 ◽  
Vol 9 (05) ◽  
pp. 617-689 ◽  
Author(s):  
GIANLUCA AMATO ◽  
FRANCESCA SCOZZARI
Keyword(s):  
Logic Programming ◽  
Static Analysis ◽  
Abstract Interpretation ◽  
Logic Programs ◽  
Semantic Operators

AbstractWe face the problems of correctness, optimality, and precision for the static analysis of logic programs, using the theory of abstract interpretation. We propose a framework with a denotational, goal-dependent semantics equipped with two unification operators for forward unification (calling a procedure) and backward unification (returning from a procedure). The latter is implemented through a matching operation. Our proposal clarifies and unifies many different frameworks and ideas on static analysis of logic programming in a single, formal setting. On the abstract side, we focus on the domainsharingby Jacobs and Langen (The Journal of Logic Programming, 1992, vol. 13, nos. 2–3, pp. 291–314) and provide the best correct approximation of all the primitive semantic operators, namely, projection, renaming, and forward and backward unifications. We show that the abstract unification operators are strictly more precise than those in the literature defined over the same abstract domain. In some cases, our operators are more precise than those developed for more complex domains involving linearity and freeness.

Stabilization of dielectric liquid bridges by electric fields in the absence of gravity

1989 ◽  
Vol 206 ◽  
pp. 545-561 ◽  
Author(s):  
H. González ◽  
F. M. J. Mccluskey ◽  
A. Castellanos ◽  
A. Barrero
Keyword(s):  
Electric Fields ◽  
Theoretical Study ◽  
Dielectric Constants ◽  
Zero Gravity ◽  
Liquid Bridges ◽  
Two Fluids ◽  
Approximate Zero ◽  
Dimensional Parameters ◽  
The Stability ◽  
Theoretical Results

The stability of liquid bridges in zero gravity conditions under the influence of an a.c. electric field tangential to the interface is examined in this paper. For the theoretical study, a static analysis was carried out to find the bifurcation surfaces as a function of the three relevant non-dimensional parameters: Λ, the slenderness or ratio of height to diameter of the cylindrical bridge; β0, the ratio of dielectric constants of the two fluids used and Ξ, a non-dimensional quantity proportional to the applied voltage. Stable and unstable regions of Λ−βo−Ξ space were distinguished. Results indicate a strong stabilizing effect for higher values of β0. The experimental study, using silicone and ricinus oil to approximate zero gravity conditions fully confirmed quantitatively the theoretical results.

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