On the construction of suitable weak solutions to the 3D Navier-Stokes equations in a bounded domain by an artificial compressibility method

In this paper we will prove that suitable weak solutions of three dimensional Navier-Stokes equations in bounded domain can be constructed by a particular type of artificial compressibility approximation

Re-Design of a Packaging Machine Employing Linear Servomotors: a Description of Modelling Methods and Engineering Tools

open4noPosition-controlled servo-systems mostly make use of electric rotary motors and gearboxes and, if necessary, a transmission mechanism to convert rotary into linear motion. Even so, especially in the field of automatic machines for packaging, it should be highlighted that most of the required movements are usually linear, so that Linear Electric Motors (LEM) should somehow represent a more convenient solution for designers. LEM can directly generate the required trajectory avoiding any intermediate mechanism, thus potentially minimizing the number of linkages/mechanical parts and, therefore, the undesired backlash and compliance that come along. On the other hand, particularly within small-medium enterprises, LEM may be rarely employed despite obvious advantages, mostly due to their high-cost as compared to rotary actuators and the lack of knowledge of the achievable performance. In light of these considerations, the present paper reports an industrial case study where an automatic machine for packaging, comprising distributed actuation and several tasks requiring a linear motion, has been completely redesigned employing different kind of LEM (i.e. iron-core and iron-less). Such machine architecture is compared to a “traditional” design where brushless gear-motors are coupled to linkage systems. The paper mainly focuses on the selection criteria for the LEM system and on the engineering tools employed during the different design stages. Qualitative and quantitative conclusions are finally drawn, which may provide useful hints for designers that are willing to actually employ LEM-based solutions in an industrial scenarioopenBerselli, Giovanni; Bilancia, Pietro; Bruzzone, Luca; Fanghella, PietroBerselli, Giovanni; Bilancia, Pietro; Bruzzone, Luca; Fanghella, Pietr

Analysis of a Reduced-Order Approximate Deconvolution Model and its interpretation as a Navier-Stokes-Voigt regularization

We study mathematical and physical properties of a family of recently introduced, reduced-order approximate deconvolution models. We first show a connection between these models and the NS-Voigt model, and that NS-Voigt can be re-derived in the approximate deconvolution framework. We then study the energy balance and spectra of the model, and provide results of some turbulent flow computations that backs up the theory. Analysis of global attractors for the model is also provided, as is a detailed analysis of the Voigt model's treatment of pulsatile flow

Increasing the Energy Efficiency of Multi-robot Production Lines in the Automotive Industry

This paper quantitatively reports bout potential energy savings on robotic assembly lines for the automotive industry. The key aspect of the proposed approach is that both cell production rate and robot hardware limitations are consideredasstrictconstraints,sothatnoplantrevisionis needed. The methodology relies on: a)calculationofenergy- optimal trajectories, by means of time scaling, concerning the robots’ motion from the last process point to the home positions; b)reduction o f the energy consumption vi aearlier release of the actuator brake whentherobotsarekeptstationary. Simulation results arepresented,whicharebasedontheproductiontiming characteristicsmeasuredonarealplant

An elementary proof of uniqueness of the particle trajectories for solutions of a class of shear-thinning non-Newtonian 2D fluids

We prove some regularity results for a class of two dimensional non-Newtonian fluids. By applying results from [Dashti and Robinson, Nonlinearity, 22 (2009), 735-746] we can then show uniqueness of particle trajectories