Structural,mechanical, and antibacterial features of curcumin/polyurethane nanocomposites

Various types of bacteria inhabit many surfaces thus causing problems which can have very strong impact on human health. Here we present a study of photophysical, mechanical, and antibacterial properties of curcumin/polyurethane nanocomposites prepared by swell-encapsulation-shrink method. The prepared nanocomposites have been characterized for degree of swelling, surface morphology, mechanical properties, chemical contents, photoluminescence, hydrophobicity, potentials for singlet oxygen generation, and antibacterial activity. Dynamic mechanical analysis has shown slight changes of glass temperature of curcumin/polyurethane nanocomposites due to blue light irradiation. It was found that nanocomposites have very strong photoluminescence, become photoactive upon blue light irradiation at 470 nm and generate singlet oxygen. Conducted antibacterial tests have shown very strong activity of these nanocomposites especially toward Escherichia coli. These bacteria strains have been eliminated completely only after 1 h irradiation by blue light. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47283.     

Effect of rapeseed oil on the rheological,mechanical and thermal properties of plastic lubricants

A strong difference in the physico-chemical properties of the plastic lubricants studied was found in this study through pressure drop, thermal analysis, vibration damping, texture hardness and rheological measurements. Oxidation aging of the lubricant sample containing rapeseed oil additive was proposed. Its higher thermal sensitivity was simultaneously confirmed by frequency dependent complex shear modulus of elasticity measurements as well as by rheological testing. Rapeseed oil modified lubricant showed a higher decrease in both storage and moduli losses due to a temperature increase from 16 to 26 ° C compared to the rapeseed oil free sample. Simultaneously, the flow curves were shifted to the higher shear stresses (for plastic lubricant without rapeseed oil additive) typical for rheopectic fluids. For the rapeseed oil modified lubricant, the flow curves were shifted to the lower shear stresses, indicating its thixotropic fluid behaviour. The synthetic lubricant without rapeseed oil additive exhibited higher dissipative rheological behaviour as reflected by decreasing first resonance frequency peak position compared to the rapeseed oil modified lubricant as obtained from vibration damping measurements. It was found that the synthetic lubricant exhibited better vibration damping properties and mechanical energy dissipation into heat due to its higher viscous friction than the rapeseed oil modified lubricant under experimental conditions.

     

Experience with an On‐board Weighing System Solution for Heavy Vehicles

Mining, construction, and other special vehicles for heavy use are designed to work under high‐performance and off‐road working conditions. The driving and executive mechanisms of the support structures and superstructures of these vehicles frequently operate under high loads. Such high loads place the equipment under constant risk of an accident and can jeopardize the dynamic stability of the machinery. An experimental investigation was conducted on a refuse collection vehicle. The aim of this research was to determine the working conditions of a real vehicle: the kinematics of the waste container, that is, a hydraulic rotate drum for waste collection; the dynamics of the load manipulator (superstructure); the vibrations of the vehicle mass; and the strain (stress) of the elements responsible for the supporting structure. For an examination of the force (weight) on the rear axle of a heavy vehicle, caused by its own weight and additional load, a universal measurement system is proposed. As a result of this investigation, we propose an alternative system for continuous vehicle weighing during waste collection while in motion, that is, an on‐board weighing system, and provide suggestions for measuring equipment designs.     

1D linear-phase band-pass multiplierless FIR Hilbert transformers and filters

An original analytical method, based on modified Christoffel–Darboux formula, is used in the paper in order to synthesise a linear-phase band-pass finite impulse response (FIR) filter function that can have an effect of Hilbert transformer. New structure of the band-pass FIR filter in recursive realisation, together with the corresponding difference equation, is presented providing the efficient filter solution without multipliers. Several examples of filter types for different parity of two real free integer parameters, including a particular solution of Hilbert transformer, are considered in terms of required number of adders and values of cut-off frequencies of the pass and stop bands. A comparison of the proposed band-pass filter characteristics with those of a classical filter solution is provided in the paper.     

Second‐order statistics of system with N‐branch microdiversity and L‐branch macrodiversity operating over gamma shadowed Nakagami‐m fading channels

The problem concerning short‐term fading and long‐term fading (shadowing) and their deleterious effects on wireless systems performance has been in focus for a long time. In this paper, motivated by the results of propagation measurements in land‐mobile and indoor‐mobile systems, and by the fact that gamma distribution can describe shadowing reliably, Nakagami‐m distribution is used to model the signal envelope and gamma distribution is used to model the average signal power. Receive diversity with maximal‐ratio combining and selection combining is implemented at the microlevel and macrolevel, respectively. The general case is explored, which assumes that microdiversity and macrodiversity are provided through arbitrary number of channels. Because shadowing has larger correlation distance than short‐term fading, correlated macrodiversity channels are studied. This paper investigates the dynamics of the received signal. A novel rapidly converging infinite‐series expression for average level crossing rate and average fade duration are obtained. Numerical results are graphically presented to examine the impact of fading severity, shadowing severity, number of diversity branches at the microlevel, number of base stations and correlation between base stations to the system's performance. Computer simulations are also performed to verify the validity and the accuracy of proposed theoretical analysis. Copyright © 2012 John Wiley & Sons, Ltd.     

Au implantation into various types of silicate glasses

The implantation of gold ions into three types of silicate glass was studied. The energies of the implanted Au⁺ ions were 1701 keV, and the fluences of the ions were 1 × 10¹⁴, 1 × 10¹⁵, 3 × 10¹⁵ and 1 × 10¹⁶ cm^?2. The as-implanted samples were annealed in air at two temperatures (400 and 600 °C). The Au concentration depth profiles were investigated using Rutherford Backscattering Spectrometry (RBS) and compared to simulated profiles from the SRIM. The structural changes were studied by UV–vis absorption spectroscopy. The obtained mono-mode waveguides were characterised using Dark Mode Spectroscopy at 671 nm to yield information on the refractive index changes. The results showed interesting differences depending on the type of glass and the post-implantation treatment. The obtained data were evaluated on the basis of the structure of the glass matrix, and the relations between the structural changes, waveguide properties and absorption, which are important for photonics applications, were formulated.     

A Characteristics Based Genuinely Multidimensional Discrete Kinetic Scheme for the Euler Equations

In this paper we present the results of a kinetic relaxation scheme for an arbitrary hyperbolic system of conservation laws in two space dimensions. We propose a new discrete velocity Boltzmann equation, which is an improvement over the previous models in terms of the isotropic coverage of the multidimensional domain by the foot of the characteristic. The discrete kinetic equation is solved by a splitting method consisting of a convection step and a collision step. The convection step involves only the solution of linear transport equations whereas the collision step instantaneously relaxes the distribution function to a local Maxwellian. An anti-diffusive Chapman-Enskog distribution is used to derive a second order accurate method. Finally some numerical results are presented which confirm the robustness and correct multidimensional behaviour of the proposed scheme.     

Model-driven engineering of process control software – beyond device-centric abstractions

This paper presents a new, two-level, model-driven engineering approach to industrial process control software. The first level (infrastructure engineering) is concerned with the following: the definition of the development process and guidelines, the definition of a domain-specific modeling language, the specification of the model transformations, and the development of a tool suite. This tool suite enables modeling of the process control software and the automatic code generation for programmable logic controllers. In the second level (application engineering), the process control software is engineered using the results of the infrastructure level. The approach is demonstrated on excerpts from an industrial project.     

Optimization,conditioning and accuracy of radial basis function method for partial differential equations with nonlocal boundary conditions—A case of two-dimensional Poisson equation

Various real-world processes usually can be described by mathematical models consisted of partial differential equations (PDEs) with nonlocal boundary conditions. Therefore, interest in developing computational methods for the solution of such nonclassical differential problems has been growing fast. We use a meshless method based on radial basis functions (RBF) collocation technique for the solution of two-dimensional Poisson equation with nonlocal boundary conditions. The main attention is paid to the influence of nonlocal conditions on the optimal choice of the RBF shape parameters as well as their influence on the conditioning and accuracy of the method. The results of numerical study are presented and discussed.