Platonic crystal with low-frequency locally resonant snail structures. Wave trapping, transmission amplification and shielding

We propose a new type of platonic crystal. The proposed microstructured plate includes snail resonators with low-frequency resonant vibrations. The particular dynamic effect of the resonators are highlighted by a comparative analysis of dispersion properties of homo- geneous and perforated plates. Analytical and numerical estimates of classes of standing waves are given and the analysis on a macrocell shows the possibility to obtain localization, wave trapping and edge waves. Applications include transmission amplification within two plates separated by a small ligament. Finally we proposed a design procedure to suppress low frequency flexural vibration in an elongated plate implementing a by-pass system re- routing waves within the mechanical system.Comment: 11 figures (20 files

Revisiting Ad-hoc Polymorphism

Ad-hoc polymorphism is a type of polymorphism where different function definitions can be given the same name. Programming languages utilize constructs like Type classes and Object classes to provide a mechanism for implementing ad-hoc polymorphism. System O, by Odersky, Wadler, and Wehr is a language which defines a dynamic semantics that supports ad-hoc polymorphism. It also describes static type checking for its programs and a transformation to the Hindley/Milner system. In this study, we present extensions to System O by defining constructs that make the language more practical to use. We utilize the dynamic semantics to define the ability to express type classes. We define additional optimizations on the transform that aim to reduce redundant function calls at run-time and simplify the generated code. Finally, we implement an interpreter for this programming language in Clojure, and provide several examples of programs utilizing ad-hoc polymorphism with the constructs we have defined

Multicloud API binding generation from documentation

We present industry experience from implementing retargetable cloud API binding generator. The analysis is implemented in Haskell, using type classes, types a la carte, and code generation monad. It also targets Haskell, and allows us to bind cloud APIs on short notice, and unprecedented scale.Comment: Presented on XP 2020: Agility in Microservices worksho

Generic parsing combinators

Parsing combinators are a well known technique to the functional programming com munity Several de nitions of them were proposed and each one has its own advantages From the programmer point of view this wide range of possibilities implies that she needs to mantain several di erent modules with several di erent namespaces but all aimed to solve the same problem Type classes and constructor classes were introduced in Functional Programming as a mean to provide overloading that is sharing of names between functions of di erent types Several design decisions can be made when implementing class systems In particular multi parameter type classes is a di cult feature to add and its addition makes sense only if extra expressiveness is achieved with them This paper proposes the use of the class system extended with multi parameter type classes to unify the de nition of parsing combinators The advantage is that di erent solutions can share their interfaces thus simplifying the programmer s activity She uses this common interface and the actual implementation is decided only changing the type signature Moreover this use of the class system is an example of the usefulness of multi parameter type classesEje: Conferencia latinoamericana de programación funcionalRed de Universidades con Carreras en Informática (RedUNCI

Contact Hypersurfaces in Uniruled Symplectic Manifolds Always Separate

We observe that nonzero Gromov-Witten invariants with marked point constraints in a closed symplectic manifold imply restrictions on the homology classes that can be represented by contact hypersurfaces. As a special case, contact hypersurfaces must always separate if the symplectic manifold is uniruled. This removes a superfluous assumption in a result of G. Lu, thus implying that all contact manifolds that embed as contact type hypersurfaces into uniruled symplectic manifolds satisfy the Weinstein conjecture. We prove the main result using the Cieliebak-Mohnke approach to defining Gromov-Witten invariants via Donaldson hypersurfaces, thus no semipositivity or virtual moduli cycles are required.Comment: 24 pages, 1 figure; v.3 is a substantial expansion in which the semipositivity condition has been removed by implementing Cieliebak-Mohnke transversality; it also includes a new appendix to explain why the forgetful map in the Cieliebak-Mohnke context is a pseudocycle; v.4 has one short remark added; to appear in J. London Math. So