INRIA a CCSD electronic archive server
Not a member yet
122212 research outputs found
Sort by
A programming language combining quantum and classical control
No full textThe two main notions of control in quantum programming languages are often referred to as "quantum" control and "classical" control. With the latter, the control flow is based on classical information, potentially resulting from a quantum measurement, and this paradigm is well-suited to mixed state quantum computation. Whereas with quantum control, we are primarily focused on pure quantum computation and there the "control" is based on superposition. The two paradigms have not mixed well traditionally and they are almost always treated separately. In this work, we show that the paradigms may be combined within the same system. The key ingredients for achieving this are: (1) syntactically: a modality for incorporating pure quantum types into a mixed state quantum type system; (2) operationally: an adaptation of the notion of "quantum configuration" from quantum lambda-calculi, where the quantum data is replaced with pure quantum primitives; (3) denotationally: suitable (sub)categories of Hilbert spaces, for pure computation and von Neumann algebras, for mixed state computation in the Heisenberg picture of quantum mechanics
Industrial codes for CFD
No full textMasterNumerical simulation in fluid mechanics (or CFD) has become one of the basic tools used by engineers. In this course, we will study the methods often used in industrial codes and we will give the most active research strategies which will be the future standards. This course does not aim at teaching the practical use of a CFD code, rather at providing the key knowledge to understand what the codes contain and how to use them in a wise manner.Prerequisites: For this course, it is necessary to have attended a course of introduction to turbulenceThe main tackled points are: 1. Introduction to CFD (Computational Fluid Dynamics) ◦ Different phases and important points of a simulation: geometric modelling, meshing, physical modelling, computation, post-processing, ◦ Evaluation of computational costs linked with turbulence, computer power available today and conclusions for modelling, ◦ Different existing methods (RANS, hybrid, LES, DNS) : objectives, formalism, modelling, maturity, fields of application, ◦ Global picture of CFD codes: commercial codes (Fluent, StarCD, CFX, Powerflow…), « in-house » industrial codes, open-source codes (Open-Foam, Code_Saturne). 2. Standard method used in industrial projects: RANS modelling (Reynolds-averaged Navier-Stokes modelling): ◦ Closure problem, different levels of modelling, history, ◦ Similarity with continuum mechanics (constitutive relations), physical principles, ◦ Eddy-viscosity modelling: hypotheses, selection of the constitutive relation, k-epsilon models, k-omega models, Spalart-Almaras model, etc.: limits, corrections, variations, ◦ Reynolds-stress modelling: hypotheses, advantages, limits, algebraic modelling, ◦ Wall regions: physics, joint selection of the mesh and the model, law of the wall, low-Reynolds number models, 3. More expensive methods: ◦ Large-eddy simulation (LES): filtering, subgrid-scale stresses, modelling, fields of application, ◦ Hybrid RANS/LES methods: • zonal methods: principle, interface modelling, • continuous methods: formalism, URANS, OES, VLES, SNS, DES, SBES, SAS, PANS, PITM, HTLE
Reachability in multi-agent transfer systems
No full textInternational audienceThis paper introduces collaborative reachability games with energy constraints. In the considered arenas, agents can spend or gain energy during moves, or share it with their peers if their current position allows it. We study several variants of energy reachability games where agents move either synchronously or asynchronously, and with/without constraints on energy transfers among peers. We show that these problems have dierent complexities ranging from NP to EXPSPACE
Genuinely multi-dimensional stationarity preserving Finite Volume formulation for nonlinear hyperbolic PDEs
No full textInternational audienceClassical Finite Volume methods for multi-dimensional problems include stabilization (e.g. via a Riemann solver), that is derived by considering several one-dimensional problems in different directions. Such methods therefore ignore a possibly existing balance of contributions coming from different directions, such as the one characterizing multi-dimensional stationary states. Instead being preserved, they are usually diffused away by such methods. Stationarity preserving methods use a better suited stabilization term that vanishes at the stationary state, allowing the method to preserve it. This work presents a general approach to stationarity preserving Finite Volume methods for nonlinear conservation/balance laws. It is based on a multi-dimensional extension of the global flux approach. The new methods are shown to significantly outperform existing ones even if the latter are of higher order of accuracy and even on non-stationary solutions
Homogeneous boundary control for a 1D reaction-diffusion PDE: modal decomposition approach
No full textInternational audienceThis paper addresses the problem of boundary stabilization for 1D linear reaction-diffusion PDE systems using the modal decomposition approach. We design nonlinear homogeneous full-state and output-feedback controllers to stabilize the unstable dynamics. We consider a linear infinite-dimensional observer for the design of the homogeneous output-feedback control. We investigate the well-posedness of the resulting closed-loop system and conduct a stability analysis by constructing a suitable Lyapunov function that accounts for the degree of homogeneity and a state-dependent switching condition based on the homogeneous norm. The properties of homogeneous-based controllers are exploited, and numerical simulations corroborate that the proposed controllers effectively mitigate peaking effects and control signal overshoot compared to classical linear boundary feedbacks designed via modal decomposition. Additional simulations are provided further to illustrate the performance of the proposed control laws
Linear Effects, Exceptions, and Resource Safety: A Curry-Howard Correspondence for Destructors
No full textDraft pre-printInternational audienceWe analyse the problem of combining linearity, effects, and exceptions, in abstract models of programming languages, as the issue of providing some kind of strength for a monad in a linear setting. We consider in particular for the \emph{allocation monad}, which we introduce to model and study resource-safety properties. We apply these results to a series of two linear effectful calculi for which we establish their resource-safety properties. The first calculus is a linear call-by-push-value language with two allocation effects new and delete. The resource-safety properties follow from the linear (and even ordered) character of the typing rules. We then explain how to integrate exceptions on top of linearity and effects by adjoining default destruction actions to types, as inspired by C++/Rust destructors. We see destructors as objects in the slice category over . This construction gives rise to a second calculus, an \emph{affine} ordered call-by-push-value language with exceptions and destructors, in which the weakening rule performs a side-effect. As in C++/Rust, a ``move'' operation is necessary to allow random-order release of resources, as opposed to last-in-first-out order. Moving resources is modelled as an exchange rule that performs a side-effect
Verified Persistent Catenable Deques
No full textInternational audienceThe simple persistent catenable deques invented by Kaplan, Okasaki, and Tarjan (2000) support insertion and extraction at either end and concatenation. They have mutable internal state and rely on a restricted form of mutation; yet they are persistent, that is, they appear to be immutable. Using Iris, we verify that they are correct in sequential and concurrent usage scenarios. Using Iris with time credits, we verify that, provided concurrent accesses are forbidden, every operation has amortized time complexity O(1). This requires repairing a certain mysterious condition in Kaplan, Okasaki, and Tarjan's description
Passivity-based Trajectory Tracking Control in Frictional Oscillators with Set-valued Friction
No full textInternational audienceThis article is largely concerned with the trajectory tracking control of frictional oscillators, which are nonsmooth nonlinear dynamical systems. The trajectory tracking problem, which is studied under a passivity-based controller addresses three main cases: the nominal case with known friction coefficient, uncertain friction coefficient, and when the Coulomb friction model is enhanced by including Stribeck effects. Monotonicity (or hypomonotonicity) of the friction model is crucial for the stability analysis of the tracking error. It can be relaxed to hypomonotonicity to handle Stribeck model. The framework of linear complementarity systems is used for the analysis. The case of a twomass system is tackled as an extension of the standard one-mass oscillator. Theoretical results are supported by numerical simulations
Computing roadmaps in unbounded smooth real algebraic sets II: algorithm and complexity
No full textInternational audienceA roadmap for an algebraic set defined by polynomials with coefficients in the field of rational numbers is an algebraic curve contained in whose intersection with all connected components of is connected. These objects, introduced by Canny, can be used to answer connectivity queries over provided that they are required to contain the finite set of query points ; in this case,we say that the roadmap is associated to .In this paper, we make effective a connectivity result we previously proved, to design a Monte Carlo algorithm which, on input (i) a finite sequence of polynomials defining (and satisfying some regularity assumptions) and (ii) an algebraic representation of finitely many query points in , computes a roadmap for . This algorithm generalizes the nearly optimal one introduced by the last two authors by dropping a boundedness assumption on the real trace of .The output size and running times of our algorithm are both polynomial in , where is the maximal degree of the input equations and is the dimension of . As far as we know, the best previously known algorithm dealing with such sets has an output size and running time polynomial in .The output size and running times of our algorithm are both polynomial in , where is the maximal degree of the input equations and is the dimension of . As far as we know, the best previously known algorithm dealing with such sets has an output size and running time respectively polynomial in and