Influence of Adaptive Gap Control Mechanism and Tool Electrodes on Machining Titanium (Ti-6Al-4V) Alloy in EDM Process

Titanium alloy is widely used for orthodontic technology and easily machined using the EDM process. In the EDM process, the workpiece and tool electrode must be separated by a continuous air gap during the machining operation to generate discharge energy in this method. In the present study, an endeavor was made to analyze the effects of a servo feed air gap control and tool electrode in the EDM process. The developed mechanical setup consists of a linear action movement with zero backlash along the X-axis, which can be controlled up to 0.03 mm. It was observed that the suggested air gap control scheme can enhance the servo feed mechanism on a machining titanium alloy. A tungsten carbide electrode can enhance the surface measures owing to its ability to produce tiny craters with uniform distribution. Since it produces a little crater and has a higher melting point, a tungsten carbide electrode can create lesser surface roughness than a copper tool and brass tool electrode.

On the module of derivations of rings of invariants of k[X,Y ] under the action of certain dihedral groups

In this paper, we study the derivation module of the ring of invariants of [Formula: see text] under the linear action of dihedral groups [Formula: see text] mentioned in a paper by Riemenschneider [Die Invarianten der endlichen Untergruppen von [Formula: see text], Math. Zeitsch. 153 (1977) 37–50]. We obtained an explicit generating set for the derivation module of [Formula: see text]. We show that [Formula: see text].

ORAGE MYSTIQUE DE FRANÇOIS DE CUREL : MISE EN QUESTION DE LA « PIÈCE BIEN FAITE »

François de Curel, dont le théâtre est tombé quelque peu dans l’oubli, est considéré comme un représentant de « pièces à thèses ». Pourtant, malgré un certain attachement de l’auteur à la tradition classique, on lui reprochait de saborder les fondements mêmes de l’art dramatique. De fait, en étudiant Orage mystique, force nous est de constater qu’il tourne résolument le dos aux principes régulateurs de la fable, principes hérités des conceptions aristotéliciennes. Si le premier acte du drame semble obtempérer aux contraintes formelles d’une « pièce bien faite », dès le deuxième, l’écrivain brise le déroulement de l’action linéaire pour se focaliser non sur la dynamique des événements, mais sur la vie psychique du protagoniste. Ce faisant, Curel semble proposer le nouveau paradigme dramatique, où, au lieu de conflits interpersonnels censés pousser l’action en avant, nous assistons à des affrontements intrasubjectifs se déroulant dans la psyché du personnage central. François de Curelis considered a representative of “problem plays”, though his theatre has fallen into oblivion. However, despite the author’s attachment to the classical tradition, he was criticized for scuttling the very fundamental dramatic art. In fact, when studying Orage mystique (Mystical Storm), it is clear that he disregards the regulatory principles of the fable, principles inherited from Aristotelian conceptions. If the first act of the drama seems to comply with the formal constraints of a “well-made play”, in the second, the writer breaks the course of the linear action to focus not on the dynamics of events, but on psychic life of the protagonist. In this way, Curel proposes a new dramatic paradigm, in which intra-subjective confrontations develop within the psyche of the central character, instead of interpersonal conflicts meant to push the action forward.

A general method to construct invariant PDEs on homogeneous manifolds

Let [Formula: see text] be an [Formula: see text]-dimensional homogeneous manifold and [Formula: see text] be the manifold of [Formula: see text]-jets of hypersurfaces of [Formula: see text]. The Lie group [Formula: see text] acts naturally on each [Formula: see text]. A [Formula: see text]-invariant partial differential equation of order [Formula: see text] for hypersurfaces of [Formula: see text] (i.e., with [Formula: see text] independent variables and [Formula: see text] dependent one) is defined as a [Formula: see text]-invariant hypersurface [Formula: see text]. We describe a general method for constructing such invariant partial differential equations for [Formula: see text]. The problem reduces to the description of hypersurfaces, in a certain vector space, which are invariant with respect to the linear action of the stability subgroup [Formula: see text] of the [Formula: see text]-prolonged action of [Formula: see text]. We apply this approach to describe invariant partial differential equations for hypersurfaces in the Euclidean space [Formula: see text] and in the conformal space [Formula: see text]. Our method works under some mild assumptions on the action of [Formula: see text], namely: A1) the group [Formula: see text] must have an open orbit in [Formula: see text], and A2) the stabilizer [Formula: see text] of the fiber [Formula: see text] must factorize via the group of translations of the fiber itself.

Skeleton-based STIP feature and discriminant sparse coding for human action recognition

PurposeTo find a successful human action recognition system (HAR) for the unmanned environments.Design/methodology/approachThis paper describes the key technology of an efficient HAR system. In this paper, the advancements for three key steps of the HAR system are presented to improve the accuracy of the existing HAR systems. The key steps are feature extraction, feature descriptor and action classification, which are implemented and analyzed. The usage of the implemented HAR system in the self-driving car is summarized. Finally, the results of the HAR system and other existing action recognition systems are compared.FindingsThis paper exhibits the proposed modification and improvements in the HAR system, namely the skeleton-based spatiotemporal interest points (STIP) feature and the improved discriminative sparse descriptor for the identified feature and the linear action classification.Research limitations/implicationsThe experiments are carried out on captured benchmark data sets and need to be analyzed in a real-time environment.Practical implicationsThe middleware support between the proposed HAR system and the self-driven car system provides several other challenging opportunities in research.Social implicationsThe authors’ work provides the way to go a step ahead in machine vision especially in self-driving cars.Originality/valueThe method for extracting the new feature and constructing an improved discriminative sparse feature descriptor has been introduced.

ЕТАПИ РОЗВИТКУ ХУДОЖНЬО-ВИРАЗНИХ СКЛАДОВИХ КОМП'ЮТЕРНИХ ІГОР

The aim of the article is to determine the main aspects of the development of a computer game in the system of audiovisual arts, to describe the chronological stages of the development of the artistic component of the work and the organization forms of the plot sequence of games. In this work, we used the method of artistic and stylistic analysis to identify the main trends in the use of artistic expressiveness, a comparatively descriptive method for analyzing the artistic and expressive solution to computer games. The technical evolution of the gaming environment for determining the stages of development of the components of a computer game is considered, which allows you to clearly define the chronological restrictions for creating works of a certain area of audiovisual art. The analysis of the means of expressiveness of computer games is carried out and it is revealed that the techniques and methods of traditional arts become an important part of the assimilation period, namely: expressiveness of first-person action, directing and musical component of games. These funds together define the unique atmosphere of the work. The directions of the artistic component of computer games are considered: a linear diagram of the sequence of actions, non-linear action and the component of "spontaneity" that form a single artistic environment. The influence of artistic-figurative means on the design of computer games is traced and the general patterns of the development of computer games in an interactive virtual environment are revealed. The results can be used for the development of artistic and expressive components of computer games, which make it possible to create a high-quality product of technological art.

Momentary Student Engagement as a Dynamic Developmental System

This article answers a call for increased scientific precision in student engagement research by contributing a definition of engagement at the microlevel grain size of individual students’ momentary involvement in academic tasks. We build on the classroom engagement framework to create a conceptualization of momentary engagement as a dynamic system comprised of parts (emotion, motivation, mental action, and physical action) existing within an overarching structure (co-action between parts) that develops as a process (a sequence of engagement triggers, non-linear action and disengagement). This new conceptualization is discussed in relation to methods of studying momentary engagement focusing on the notions of complexity, emergence and dynamics. We conclude by calling for a paradigm shift in research on student engagement.

DISTALITY OF CERTAIN ACTIONS ON -ADIC SPHERES

Consider the action of $\operatorname{GL}(n,\mathbb{Q}_{p})$ on the $p$-adic unit sphere ${\mathcal{S}}_{n}$ arising from the linear action on $\mathbb{Q}_{p}^{n}\setminus \{0\}$. We show that for the action of a semigroup $\mathfrak{S}$ of $\operatorname{GL}(n,\mathbb{Q}_{p})$ on ${\mathcal{S}}_{n}$, the following are equivalent: (1) $\mathfrak{S}$ acts distally on ${\mathcal{S}}_{n}$; (2) the closure of the image of $\mathfrak{S}$ in $\operatorname{PGL}(n,\mathbb{Q}_{p})$ is a compact group. On ${\mathcal{S}}_{n}$, we consider the ‘affine’ maps $\overline{T}_{a}$ corresponding to $T$ in $\operatorname{GL}(n,\mathbb{Q}_{p})$ and a nonzero $a$ in $\mathbb{Q}_{p}^{n}$ satisfying $\Vert T^{-1}(a)\Vert _{p}<1$. We show that there exists a compact open subgroup $V$, which depends on $T$, such that $\overline{T}_{a}$ is distal for every nonzero $a\in V$ if and only if $T$ acts distally on ${\mathcal{S}}_{n}$. The dynamics of ‘affine’ maps on $p$-adic unit spheres is quite different from that on the real unit spheres.

Invariant Whitney functions

Theorem 1 of [G. W. Schwarz, Smooth functions invariant under the action of a compact Lie group, Topology 14 (1975) 63–68.] says that for a linear action of a compact Lie group [Formula: see text] on a finite dimensional real vector space [Formula: see text], any smooth [Formula: see text]-invariant function on [Formula: see text] can be written as a composite with the Hilbert map. We prove a similar statement for the case of Whitney functions along a subanalytic set [Formula: see text] fulfilling some regularity assumptions. In order to deal with the case when [Formula: see text] is not [Formula: see text]-stable, we use the language of groupoids.