Report of the Italian inter-laboratories comparison of high dc resistance on the calibration of a and a resistors

A national comparison of high dc resistance at and level was organized by the Electromagnetic Division of National Institute of Metrological Research (INRIM, Italy) and piloted by the high dc resistance Laboratory of the same Division. This comparison took place between January and April 2008 with the participation of 8 Secondary Laboratories accredited by the Italian Service of Accreditation of Calibration Laboratories (SIT). The travelling package included one wire-wound standard and one thick film-type standard in a wooden anti-shock container designed by INRIM. The obtained results indicate that the relative differences at and between each Laboratory’s value and the respective reference value are all within the expanded relative uncertainties of these differences at a 2σ confidence level.     

Tribological evaluation of α, -diimidazoliumalkylene hexafluorophosphate ionic liquid and benzotriazole as additive

Ionic liquids of α, -diimidazoliumalkylene hexafluorophosphate were synthesized. The tribological properties of the synthetic ionic liquid and the ionic liquid contained additive for contacts of steel/steel were investigated by Optimol SRV oscillating friction and wear tester under ambient conditions. The synthetic ionic liquid presented low friction coefficients and small wear volumes, especially under higher temperatures. The ionic liquid doped with benzotriazole (BTA) showed excellent anti-wear ability. The worn surfaces and chemical nature of the boundary films generated on the metal surfaces were analyzed by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). SEM results showed slight abrasion on the worn surfaces and XPS results indicated the formation of FeF₂, FeF₃, Fe₃O₄, and FePO₄ by the tribochemical reactions of ionic liquid with iron during the sliding process.     

Finite time stability and controller design for nonlinear impulsive sampled-data systems with applications

This paper investigates the finite time stability (FTS) for nonlinear impulsive sampled-data systems. By constructing an appropriated Lyapunov function and employing average impulsive interval (AII) method, some FTS criteria for the nonlinear impulsive sampled-data systems are derived in terms of linear matrix inequalities (LMIs), which can be easily verified via the LMI toolbox. The hybrid controller including sampled-data controller and impulsive controller is designed via the established LMIs. Moreover, the impulse effect considered in this paper including stabilizing impulse and destabilizing impulse. Our developed results are less conservative than the recent work in the literature. Finally, two numerical examples are provided to show the applications of the proposed criteria.     

Improved stabilization method for networked control systems with variable transmission delays and packet dropout

This paper investigates the problem of stability analysis and stabilization for networked control systems with the network-induced delay and data dropout. In order to obtain less conservative results, a novel augmented Lyapunov–Krasovskii functional is introduced and new free-weighting matrices are employed to make some extra degrees of freedom in the sufficient stabilizability condition. The gain of the memoryless state-feedback controller is computed by solving a set of linear matrix inequalities (LMIs). Illustrative examples are given to verify the applicability and outperformance of the proposed method compared to the existing approaches in the literature.     

Anti-wear and friction reducing additives composed of ortho-phenylene phosphate-amine salts for polyether type base stocks

Lubrication properties of amine salts of diaryl phosphates in polyether type base oils were evaluated by means of the four-ball wear test. The unique cyclic phosphate, ortho-phenylene phosphate, prevented wear and reduced friction when combined with tertiary amines. Adsorptivity, solubility, and corrosivity of the additives were taken into account.     

Forward kinematic problem of 5-RPUR parallel mechanisms (3T2R) with identical limb structures

This paper investigates the formulation of the forward kinematic problem of the 5-DOF parallel mechanisms performing three translation and two independent rotations with identical limb structures. The mathematical framework used in this paper is based on algebraic geometry where the forward kinematic problem is explored in a seven-dimensional kinematic space by the means of the so-called Study parameters. In this paper, the algorithms proposed for obtaining the forward kinematic expression is based on two approaches which differ by their concept of eliminating passive variables. The first one is based on the application of the so-called resultant method and the second one, as a novel approach referred to as linear implicitization algorithm, uses an elimination procedure based on solving several systems of linear equations. The forward kinematic problem is solved using the homotopy continuation and it is revealed that it has 1680 finite solutions. Moreover, the forward kinematic problem is studied in three-dimensional Euclidean space where a class of simplified designs are proposed which admit a simpler formulation for the forward kinematic problem. Finally, based on the simplified designs, for a nearly general design a univariate expression of degree 220 is obtained.