Search results for "Volt"
showing 10 items of 2187 documents
Inverse Polarography and Voltammetry: New Methods for Trace Analysis
1962
Inverse polarographic and voltammetric methods are surveyed. The electrochemical determination procedure is carried out by current reversal after electrolytic concentration on a working electrode. Analyses in the nanogram (ng) region (10−9 g.) are possible because the sensitivity is increased by a factor of 100 to 1000 in comparison with the usual polarographic and voltammetric methods. These methods are, therefore, of particular interestin trace analysis.
Platinum levels in urban soils from Palermo (Italy); Analytical method using voltammetry
2011
Abstract A fast accumulation of platinum in the environmental and biological matrices was observed in the last years and concern arose about potential environmental and health risks. The toxicity of platinum species has been investigated in various studies, some of their, especially the chlorinated ones, are very toxic and allergenic. Information of the acute toxicity of some Pt-chlorinated salts and evidence of DNA damage due to Pt exposure have been observed both in vitro and in vivo. Taking into account what is written above, the development of reliable analytic methods to measure very low Pt concentrations is required. In this work was developed a reliable method for the determination o…
Platinum and rhodium associated with the leaves of Nerium oleander L.; analytical method using voltammetry; assessment of air quality in the Palermo …
2009
Abstract A rapid accumulation of the catalytic active noble metals in the environmental and biological matrices was observed and concern arose about potential environmental and health risks. The development of reliable analytic methods to measure very low Pt and Rh concentrations is required. The main purpose of this work was to develop a reliable method for the determination of Pt and Rh in environmental matrices because of inherent difficulties in using conventional techniques used, in particular, the ICP-OES technique. A direct determination of Pt using ICP-MS, for instance, is problematic, due to interfering signals. In this work, differential pulse voltammetry (DPV/a) and adsorptive st…
Water-soluble and redox-responsive hyperbranched polyether copolymers based on ferrocenyl glycidyl ether
2015
Water-soluble copolymers of ferrocenyl glycidyl ether (fcGE) and glycidol were prepared via anionic ring-opening multibranching polymerization (ROMBP). The resulting hyperbranched materials with molecular weights (Mn) of 3500 to 12 300 g mol−1 and relatively narrow molecular weight distributions (Mw/Mn = 1.40–1.69) exhibit both temperature- as well as redox-responsive behavior, which was studied via turbidity measurements. The cloud point temperatures (Tc) were adjusted between 45 and 60 °C through variation of the fcGE comonomer content. Additionally, these Tcs can be increased by the addition of an oxidizing agent. The extent of oxidation of the materials was quantified by Mosbauer spectr…
Selective harmonic mitigation with asymmetrical staircase voltage waveform for a three-phase five-level Cascaded H-Bridge Inverter
2020
Selective harmonics elimination or mitigation strategies are used in all applications where it is necessary to rise the efficiency and reliability of the overall system. This paper presents a simple approach to reduce the low order harmonics amplitude of an asymmetrical staircase voltage waveform for a five-level, three-phase Cascaded H-Bridge Inverter without solving non-linear equations. Through this simple approach, polynomial equations to evaluate the control angels in real-time operations have been found. The effectiveness of the harmonic mitigation method has been tested through the simulation analysis in MatLab/PLECS environment.
A Novel Computational Approach for Harmonic Mitigation in PV Systems with Single-Phase Five-Level CHBMI
2018
In this paper, a novel approach to low order harmonic mitigation in fundamental switching frequency modulation is proposed for high power photovoltaic (PV) applications, without trying to solve the cumbersome non-linear transcendental equations. The proposed method allows for mitigation of the first-five harmonics (third, fifth, seventh, ninth, and eleventh harmonics), to reduce the complexity of the required procedure and to allocate few computational resource in the Field Programmable Gate Array (FPGA) based control board. Therefore, the voltage waveform taken into account is different respect traditional voltage waveform. The same concept, known as “voltage cancelation”, used for single-…
Nonmonotonic Pattern Formation in Three Species Lotka-Volterra System with Colored Noise
2005
A coupled map lattice of generalized Lotka-Volterra equations in the presence of colored multiplicative noise is used to analyze the spatiotemporal evolution of three interacting species: one predator and two preys symmetrically competing each other. The correlation of the species concentration over the grid as a function of time and of the noise intensity is investigated. The presence of noise induces pattern formation, whose dimensions show a nonmonotonic behavior as a function of the noise intensity. The colored noise induces a greater dimension of the patterns with respect to the white noise case and a shift of the maximum of its area towards higher values of the noise intensity.
Optimal Control of the Lotka-Volterra Equations with Applications
2022
In this article, the Lotka-Volterra model is analyzed to reduce the infection of a complex microbiote. The problem is set as an optimal control problem, where controls are associated to antibiotic or probiotic agents, or transplantations and bactericides. Candidates as minimizers are selected using the Maximum Principle and the closed loop optimal solution is discussed. In particular a 2d-model is constructed with 4 parameters to compute the optimal synthesis using homotopies on the parameters.
Clarification of the oxidation state of cobalt corroles inheterogeneous and homogeneous catalytic reduction of dioxygen
2008
Co(III) corroles were investigated as efficient catalysts for the reduction of dioxygen in the presence of perchloric acid in both heterogeneous and homogeneous systems. The investigated compounds are (5,10,15-tris(pentafluorophenyl)corrole)cobalt (TPFCor)Co, (10-pentafluorophenyl-5,15-dimesitylcorrole)cobalt (F 5PhMes 2Cor)Co, and (5,10,15-trismesitylcorrole)cobalt (Mes 3Cor)Co, all of which contain bulky substituents at the three meso positions of the corrole macrocycle. Cyclic voltammetry and rotating ring-disk electrode voltammetry were used to examine the catalytic activity of the compounds when adsorbed on the surface of a graphite electrode in the presence of 1.0 M perchloric acid, a…
Design and performance evaluation of a high power density EMI filter for PWM inverter-fed induction motor drives
2015
This paper presents the design of an electromagnetic interference (EMI) filter for a low voltage high current induction motor drives supplied by DC power grids, such as those used in several vehicle applications. In order to effectively design the EMI filter a suitable Common Mode/Differential Mode (CM/DM) separation technique has been used. In consideration of the high operating currents, a software based separation technique using time domain measurements has been applied. The proposed technique allows the CM and DM sections of the EMI filter to be properly selected in a more economical way, i.e. without the need of dedicated hardware or costly radio frequency (RF) instrumentation. The de…