Design of sliding mode and model reference adaptive control strategies for multivariable tape transport mechanism: a performance comparison

This paper presents sliding mode control and model reference adaptive control strategies for the tape transport mechanism. A nonlinear multivariable MIMO model of the process, consisting of take-up and supply reel servos for tape tension control and capstan servo for speed control is considered. The sliding mode control is applied for the nonlinear dynamic model of the process, while the model reference adaptive control deals with the linearized one. Moreover, in order to associate with the realistic model of system, design of controllers is accomplished with respect to parametric uncertainties. It is shown that both control strategies can guarantee asymptotic stability of the closed-loop system and tracking of desired outputs with the appropriate pace in the presence of uncertainties. Finally, simulation results demonstrate the effectiveness of the proposed controllers.     

Statistical analysis of the performance of a bi-functional catalyst under operating conditions of LPDME process

Liquid phase direct synthesis of dimethyl ether (LPDME™) under various operating conditions (temperature, H₂/CO molar ratio of feed) was conducted in a mechanically agitated slurry reactor system. Each run was monitored for 60 h time on stream (TOS) in order to confirm the high activity and long-term stability of a bi-functional catalytic system (CuO–ZnO–Al₂O₃/H-MFI-90). Statistical experimental design was applied for determining the optimum operating conditions under which the catalytic system shows the highest performance. A significant improvement in the performance of the bi-functional catalyst was observed when the temperature and H₂/CO molar ratio of feed were increased from 200 to 240 °C and 1 to 2, respectively at a constant pressure of 35 bar and GHSV equal to 1100 mLn/(g-cat h). CO conversion was increased from 9.1 mol% at T = 200 °C and H₂/CO = 1 to 79.6 mol% at T = 240 °C and H₂/CO = 2 and the yield and selectivity of DME also increased from 7.11% to 47.05% and 41.57% to 59.96%, (molar basis) respectively. No significant deactivation has been observed during 60 h TOS at different operating conditions. Furthermore, from the main effect plots and response table results, it was concluded that the most effective factor on activity and stability of bi-functional catalytic system is temperature.     

Evaluation of MODIS data for improved monitoring of the Caspian Sea

Moderate-Resolution Imaging Spectroradiometer (MODIS) optical and infrared data are used to monitor changes in the Caspian Sea coastline. The information extracted from MODIS images is converted into total water volume and mean lake level by combining a digital elevation model (DEM) with remote-sensing data. The elevation estimates were enhanced by reprocessing the MODIS data at the sub-pixel scale. The water volume variations estimated from MODIS data along with DEM are compared to other estimations derived from altimetry data sets, and show fair agreement.     

A charge sharing–based switching scheme for SAR ADCs

This paper presents an energy-efficient switching scheme for successive approximation register (SAR) analogue-to-digital converter (ADC). The proposed scheme employs charge recycling method to keep the capacitor arrays free of transitional energy between bit generations except reset phase. In comparison with the conventional switching scheme, the proposed one achieves 100% transitional energy saving without considering reset phase. In addition, configuration of a 10-bit SAR ADC shows that the proposed switching scheme reduces the capacitor area by 25% compared with the conventional switching scheme.     

Fault‐tolerant control of distributed systems by information pattern reconfiguration

Given a fault‐tolerance strategy and a distributed control system, the set of recoverable faults depends on the information pattern that is implemented. This paper shows that fault‐tolerance can be achieved, when possible, by the reconfiguration of the information pattern. A necessary and sufficient recoverability condition is provided, and sub‐optimal solutions are developed for actuator and sensor faults under system reconfiguration. Copyright © 2014 John Wiley & Sons, Ltd.     

Deactivation of Pt/wire-mesh and vanadia/monolith catalysts applied in selective catalytic reduction of NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> in flue gas

In this study the deactivation of Pt/wire mesh and vanadia/monolith catalysts by aerosol particles of some inorganic salts (K₂SO₄, KCl and ZnCl₂) with high or low melting points has been investigated. The aerosol particles may either diffuse within the matrix of the catalysts and block the mezzo and micro pores, or deposit on the outer surface of the catalysts and form a porous layer causing a mass transfer resistance that ultimately deactivates the catalysts. It has been observed that in both Pt/wire mesh and vanadia/monolith catalysts the deactivation effect of ZnCl₂ was more pronouced compared to other salts. As an example, after 31 hours of exposure to ZnCl₂, 10% of the catalysts activities was lost. This may be related to the ZnCl₂ lower melting point in comparison with other poisons. These results are in agreement with the previous findings for deactivation of wire-mesh catalysts used for oxidation of volatile organic compounds (VOC) and CO by exposing the catalysts to the aerosols generated from inorganic salts.     

DFNS/PEI/Cu Nanocatalyst for Reduction of Nitro-aromatic Compounds

Catalysis Letters - Nitro-aromatic pollution in industrial waste streams threat wellbeing of water resources. This study investigates the performance of a copper-based nano catalyst to reduce...     

Design factors affecting the dynamic performance of soil suspension in an agitated,baffled tank

The effects of particle size, impeller clearance and impel er speed are assessed to show how condition variations influence power consumption in the water-solid slurry suspension in an agitated tank. The energy efficiency of slurry height variation, impel er type and diameter, and solid movement speed has been investigated with six soil series stirred in a soil-water slurry. Coarser sand particles are observed to significantly increase power consumption, while finer particles, for instance clay, decrease the stirring power requirement. The 3-blade HR100 SUPERMIX? impeller manufactured by SATAKE general y performs more efficiently than a conventional 4-pitched blade turbine. The impeller's geometric design, including diameter and number of blades influences the impeller's energy efficiency, and HR100 impellers with greater diameters remarkably reduce power consumption. The tests demonstrated that the power required to provide off-bottom solid suspension and solid dispersion can be reduced dramatically by increasing the slurry height rather than by accelerating the impel er, if this option is possible.     

Adaptive fuzzy-SIFT rule-based registration for 3D cardiac motion estimation

Applied Intelligence - 3D Speckle tracking techniques are used to quantify cardiac deformation in 3D echocardiographic images. Elastic image registration methods are successful in solving 3D...