A control strategy for energy optimal operation of a direct district heating system

A dynamic model of a direct district heating system (DDHS) is developed, and an energy optimal control strategy is designed. The DDHS is characterized as a system with long transport time delay. The use of a Smith predictor (SP) to deal with this type of time delay is explored. An SP is designed by using the reduced‐order dynamic model and implemented on the full‐order model. Also, optimal set point profiles of supply water temperature as a function of outdoor air temperature have been determined. The simulation results show that the SP works effectively in disturbance rejection compared with the nominal control design. The use of optimal set point control strategy resulted in energy savings of the order of 19–32% when the influence of internal load was considered. Copyright © 2004 John Wiley & Sons, Ltd.     

Surfactant-Mediated Catalytic Determination of Fe(II) in Herbal and Pharmaceutical Products

In the present work, the catalyzed oxidation of neutral red (NR) by bromate was used to work out a kinetic-based analytical method as an alternative technique for the determination of Fe(II) in real and synthetic samples. A use of a surfactant, N-dodecylpyridinium chloride enhanced the sensitivity of the reaction by becoming involved in the reaction mechanism and providing a more suitable reaction environment. The iron-catalyzed oxidation of NR with potassium bromate was studied kinetically by using a fixed time method. The reaction was followed by measuring the decrease in absorbance at 535 nm. The use of a surfactant in the analytical run showed a five times increase in the sensitivity of the method. It served as a ready reservoir of NR by increasing its solubilization. The salt effect, pH, and reagent concentration were also investigated to achieve a more selective and sensitive analytical procedure. Under optimized conditions (4.2 × 10⁻⁵ mol L⁻¹ NR, 1.4 × 10⁻³ mol L⁻¹ KBrO₃, 1.5 × 10⁻² mol L⁻¹ cationic surfactant, 0.5 mol L⁻¹ LiCl and pH 2.60 at 30 °C), iron(II) was determined in the range 0.1–0.5 μg mL⁻¹ with a detection limit of 0.019 μg mL⁻¹ and a relative standard deviation (n = 6) 1.02% for 0.2 μg mL⁻¹ Fe(II). The influence of foreign ions on the accuracy of the results was investigated. The developed method is extremely sensitive, selective and simple. The method was applied successfully to the determination of iron in the herbal pharmaceutical and synthetic samples. The results showed good agreement with those obtained by atomic absorption spectrophotometry.

One-dimensional porous journal bearings lubricated with micropolar fluid

One-dimensional journal bearings lubricated with a micropolar fluid were analysed. It was found that the load capacity increased and the coefficient of friction decreased as the micropolar parameter characterizing the concentration of substructures in the lubricant due to the presence of additives increased. The load capacity decreased and the coefficient of friction increased as the parameter characterizing porosity increased.     

Catalytic synthesis of biodiesel from pongamia glabra over zirconia and its modified forms

Zirconia & its modified forms such as Mo(VI)/ZrO₂, Pt-SO ₄ ^2? /ZrO₂, MgO & MgO-ZrO₂ mixed oxide were prepared by impregnation method. These catalysts were analyzed for surface acidity, surface basicity and crystallinity by using techniques such as TPD & powder X-ray diffraction. Mo(VI)/ZrO₂, Pt-SO₄ ^2?/ZrO₂ were used as solid acid catalysts for esterification of pongamia glabra (karanja) oil to reduce the concentration of free fatty acid and MgO and MgO-ZrO₂ mixed oxide were used as solid base catalysts for transesterification of karanja oil to produce biodiesel. These zirconia catalysts were found to be highly efficient for the synthesis of biodiesel with more than 90% yield of biodiesel. These solid catalysts can be effectively reactivated and reused.     

A fuzzy model for noise-induced annoyance

This paper proposes a novel approach for modeling noise-induced annoyance using the fuzzy technique. The fuzzy approach offers a convenient way of representing the relationships between the inputs and outputs of a system in the form of simple IF-THEN rules. Annoyance, in the present model, is considered as a function of noise level, its duration of occurrence, and the socioeconomic status of a person. The model has been implemented on the Fuzzy Logic Toolbox of MATLAB, using both Mamdani and Sugeno techniques. The results of the model are applicable to the urban areas of India.     

Analysis of step bearings with a micropolar lubricant

Squeeze film step bearings lubricated with a micropolar fluid were analysed. It was found that the load capacities increase as the micropolar parameter $\text{}\text{?}\text{gm}{}_1$ increases or as $\text{M =}\text{h}{}^2\text{μ}\text{4γ}$ decreases. The load capacity also decreases as the step height increases.     

PAPR Reduction in OFDM Signals: An Adaptive-Network-Based Fuzzy Inference Approach

In this paper, an adaptive-network-based fuzzy inference system (ANFIS) based scheme is analyzed and proposed for reducing the peak-to-average power ratio (PAPR) in multicarrier signals under additive white Gaussian noise and multipath fading (Raleigh) channel environment. This scheme involves training of ANFIS structure in time domain using Orthogonal Frequency Division Multiplexing signals with low PAPR, such as those obtained by approximate gradient project–null subcarrier switching (AGP–NCS) method. Once the ANFIS module is trained, the proposed scheme approximately offers similar reduction in PAPR as compared to AGP–NCS method, with significantly less convergence time and computational complexity. he results show that proposed approach is not only less complex but also maintains the data rate and bit error rate performance compared with other conventional schemes.     

Inertia effects in magnetohydrodynamic porous conducting thrust bearings

The effects of fluid inertia in an externally pressurized porous conducting thrust bearing in the presence of a transversely applied magnetic field are theoretically analysed. The load capacity increases and the flow flux decreases as the fluid inertia term, the applied magnetic field or the conductivity of the plate increases. Both the load capacity and the flow flux increase with increasing permeability of the plate.