An extended inner–outer factorisation algorithm based on the structure of a transfer function matrix inverse

In this paper, the structure feature of the inverse of a multi-input/multi-output square transfer function matrix is explored. Instead of complicated advanced mathematical tools, we only use basic results of complex analysis in the analysing procedure. By employing the Laurent expression, an elegant structure form of the expansion is obtained for the transfer function matrix inverse. This expansion form is the key of deriving an analytical solution to the inner–outer factorisation for both stable plants and unstable plants. Different from other computation algorithm, the obtained inner–outer factorisation is given in an analytical form. The solution is exact and without approximation. Numerical examples are provided to verify the correctness of the obtained results.     

Smart SCADA system for urban air pollution monitoring

There are a number of different types of monitoring stations for checking air quality levels in urban environments. These monitoring stations usually just perform data acquisition of the measured values from the sensors and store them in the database. The processing of the measured results as well as the statistical analysis is mainly done in other places where the data come from various communication systems. Acquisition of the measured data is commonly done on-line while the processing and statistical analysis is performed off-line. As opposed to these measurement systems, this implemented device enables the acquisition and statistical processing of the measured data in real time and the results are instantly available to all users. The system indicates the air pollutants using the ARMA model. The transmission of information in the realized smart SCADA system is done by the Modbus protocol using shared variables which gives the whole system a stronger hierarchical structure.     

Terrific effect of H2 on 3D free convection MHD flow of C2H6O2H2O hybrid base fluid to dissolve Cu nanoparticles in a porous space considering the thermal radiation and nanoparticle shapes effects

In this article, the physical aspects of natural convection magnetohydrodynamic flow of Cu/Ethylene glycol-water nanofluid past a porosity vertical stretching sheet under impact of thermal radiation, shape and slip factor and suction/injection process has been analyzed using Runge- Kutta Fehlberg fifth order (RKF 5) numerical method. The influence of variable, different parameters such as nanoparticles shape factor, named hexahedron and Lamina on temperature and velocity profiles are exemplified quantitatively through graphs. Outputs demonstrate thermal radiation impact causes to produce heat and increase the temperature profile by increasing nanofluid molecules energy. Lamina shape nanoparticle has a greater effect on increasing Nusselt number (Nu) compared to hexahedron.     

Polyaniline sensitized Pt@TiO2 for visible-light-driven H2 generation

Polyaniline is a typical conducting polymer with high migration electron rate, good stability, eco-friendly properties, and high absorption coefficients for visible light. In the present study, polyaniline decorated Pt@TiO₂ for visible light-driven H₂ generation is reported for the first time. The above-mentioned nanocomposite is prepared through a simple oxidative-polymerization and characterized by infrared spectroscopy, transmission electron microscopy, X–ray diffraction, thermogravimetric analysis, and ultraviolet–visible diffuse reflectance spectra. Polyaniline modification improves the absorption of the nanocomposite in visible light region via a photosensitization effect similar to dye–sensitization but does not influence the crystal structure and size of Pt@TiO₂. The polyaniline modified Pt@TiO₂ exhibits a remarkable visible light activity (61.8 μmol h⁻¹ g⁻¹) and good stability for H₂ generation (with an average apparent quantum yield of 10.1%) with thioglycolic acid as an electron donor. This work provides new insights into using conducting polymers, including polyaniline, as a sensitizer to modify Pt@TiO₂ for visible-light hydrogen generation.     

A hybrid fuel cell system integrated with methanol steam reformer and methanation reactor

In this paper, a hybrid fuel cell system integrated with methanol steam reformer and methanation reactor is demonstrated. Methanol steam reformer employed in this system is to produce hydrogen-rich reformate in connection with a methanation reactor to reduce the carbon monoxide content effectively, and the reformate gas is sent into a low-temperature polymer electrolyte fuel cell for direct electric power generation. The optimum conditions (temperature, water to methanol ratio, and space velocity) for methanol steam reforming (MSR) reaction and methanation (MET) reaction are verified by experiments. A comparison between pure hydrogen, reformate surrogate, and actual reformate is performed. The results show that the power density of this hybrid system achieves 245.2 mW/cm² while it achieves 268.8 mW/cm² when employing pure hydrogen as the fuel. An alternative novel method to solve the problem of hydrogen storage and transportation is provided and the in-situ hydrogen production and utilizing through low-temperature fuel cell system is realized, which is helpful to accelerate the commercialization process of the fuel cell.     

Load frequency control of an autonomous hybrid power system by quasi-oppositional harmony search algorithm

This paper deals with a novel quasi-oppositional harmony search algorithm (QOHSA) based design of load frequency controller for an autonomous hybrid power system model (HPSM) consisting of multiple power generating units and energy storage units. QOHSA is a novel improved version of music inspired harmony search algorithm for obtaining the best solution vectors and faster convergence rate. In this paper, the efficacy of the proposed QOHSA is adjudged for optimized load frequency control (LFC) of an autonomous HPSM. The studied HPSM consists of renewable/non-renewable energy based generating units such as wind turbine generator, solar photovoltaic, solar thermal power generator, diesel engine generator, fuel cell with aqua-electrolyzer while energy storage units consists of battery energy storage system, flywheel energy storage system and ultra-capacitor. Gains of the conventional controllers such as integral (I) controller, proportional–integral (PI) controller and proportional–integral–derivative (PID) controller (installed as frequency controller one at a time in the proposed HPSM) is optimized using QOHSA to mitigate any frequency deviation owing to sudden generation/load change. In order to corroborate the efficacy of QOHSA, performance of QOHSA to design optimal LFC is compared with that of other well-established technique such as teaching learning based optimization algorithm (TLBOA). The comparative performances of the HPSM under the action of QOHSA/TLBOA based optimized conventional controllers (I or PI or PID) are investigated and compared in the present work. It is found that the QOHSA tuned frequency controllers improves the overall dynamic response in terms of settling time, overshoot and undershoot in the profile of frequency deviation and power deviation of the studied HPSM.     

An innovating application of PEM fuel cell: Current source controlled by hydrogen supply

Fuel cells are complex systems which can be considered as low voltage electrical source. Preliminary investigations led with a single proton exchange membrane fuel cell, either short-circuited or hybridized by discharged supercapacitors, could evidence the behavior as a current source, in which the current is directly controlled by the hydrogen flow rate. This operation mode imposes the fuel cell voltage to be far below the threshold recommended by the fuel cell manufacturer. The paper deals with this unusual application of fuel cell and its benefits such as the high quality current, free of oscillations that might be upgraded for superconducting coil supply. To investigate this operation mode an appropriate single fuel cell model is established and then validated by means of a test bench equipped with a proton exchange membrane single fuel cell.     

Flexible Low-Melting Point Radiation Shielding Materials: Soft Elastomers with GaInSnPbBi High-Entropy Alloy Inclusions

A polydimethylsiloxane (PDMS) matrix soft elastic composite material with low-melting-point GaInSnPbBi high-entropy alloy (LHEA) inclusions is prepared to evaluate its radiation shielding performance. The LHEA is composed of two different three-component eutectic microstructures, which are grown in a mixed manner to form a complex eutectic structure. The inclusions have excellent mechanical properties that matched the deformation of the PDMS matrix. To evaluate the interaction of the shielding material with photons, the Monte Carlo N-Particle Extended and XCOM codes are used to determine the shielding parameters of the LHEA/PDMS composites, such as mass attenuation coefficient, linear attenuation coefficient, half-value layer, tenth value layer, mean free path, and effective atomic number. The composite with 50-vol% LHEA has the best radiation shielding properties, validated by medical X-ray imaging experiments. The excellent shielding properties of the flexible lightweight composites are attributed to the higher mass attenuation coefficient of the LHEA inclusions than that of lead.     

Mild synthesis of benzylated bamboo in LiCl/DMSO solution

Benzylated bamboo was mildly synthesized in nonaqueous medium without mercerization pretreatment. The ball-milled bamboo was firstly preswelled in lithium chloride/dimethyl sulfoxide (LiCl/DMSO) solution and then reacted with benzyl chloride in the presence of solid NaOH with varying molar ratios of benzyl chloride to OH groups of bamboo (1–4), reaction times (1–8 h), and temperatures (60–90°C). Benzylated bamboo products with yields from 51.1 to 106.9% and with degrees of substitution [DS, apparent value evaluated by Fourier transform infrared (FTIR) spectra] between 0.2 and 1.2 were synthesized. FTIR and ¹³C cross polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy confirmed the incorporation of benzyl groups into bamboo; SEM observations of the highly benzylated bamboo showed porous surface with small irregular slices ascribed to the disruption of intermolecular and intramolecular hydrogen bonds between cellulose. Because of the degradation of amorphous components, the crystallinity decreased negligibly after modification and the thermal stability increased slightly but was lower than that of cellulose. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Frequency and phase estimation in time series with quasi periodic components

In this article, we consider frequency and phase estimation in a noisy oscillation with potentially non‐constant phase increments resulting from an underlying non‐constant frequency. A maximum periodogram method on segments is used to estimate the time‐varying frequency and a subsequent least squares approach to estimate the phase. A key problem addressed in this article is the question how to set up a meaningful concept of asymptotic statistics for this model. This problem is solved by a special infill asymptotics concept. We use this concept to prove consistency and asymptotic normality of the estimates. Furthermore, the phase estimate is compared to the Hilbert transform in a simulation.