Frequency Regulation in Hybrid Power System Using Iterative Proportional-Integral-Derivative H ∞ Controller

This study considers frequency regulation in a hybrid power system consisting of conventional and distributed generation resources. The performance of two controllers—an H _∞ design via linear matrix inequalities and an iterative proportional-integral-derivative H _∞ via linear matrix inequalities—is assessed to maintain frequency deviation profile in acceptable limits. In the latter control design, the iterative linear matrix inequality approach is used to tune proportional-integral-derivative controller parameters subjected to H_∞ constraints in terms of the iterative linear matrix inequality. The efficacy of the control law and disturbance accommodation properties is shown. The robustness of these controllers is demonstrated in the hybrid power system with different load disturbance conditions, wind power, and parameter variations. Controller performance is compared with a suboptimal controller to demonstrate its superiority. It is found that the second controller design has satisfactory disturbance rejection properties and robustness against parameter variations over a wide range of conditions.     

Characterization of polyethylene terephthalate/polyaniline blends as potential antioxidant materials

Polyethylene terephthalate (PET) blends with a nanorod form of polyaniline (NR-PANI), formed by a falling pH synthesis, were prepared by dispersion in a melt of PET at 265 °C. Blends with 1, 2 and 3 wt% NR-PANI loading were prepared. Optical microscopy revealed an even distribution of NR-PANI particles within the PET matrix. The blends were characterized using FTIR, XPS, DSC and DMTA. Melt flow index values suggested hydrolysis of PET chains to lower molecular weight units when NR-PANI was blended. Some PET hydrolysis was also evident from the increasing oxygen to carbon ratios with an increased NR-PANI content in the blends. While the PET glass transition temperature remained relatively unaffected, the degree of PET crystallinity was increased with the addition of NR-PANI. The electrical conductivity as well as the free radical scavenging capacity of PET increased with greater NR-PANI loading in the matrix. The mechanical properties of PET, however, declined with NR-PANI loading suggesting a lack of adequate interfacial adhesion between the NR-PANI particles and the PET matrix.     

Bayesian analysis of the mixture of exponential failure distributions

In this paper, a Bayesian reliability analysis is carried out for the mixture of two exponential failure distributions on the basis of failure time data x₁ < x₂ <…< x_r, for a preassigned r, and (n − r) survivors from this mixed failure model. Under the assumptions of the squared error loss function (SELF) and suitable prior densities on the underlying parameter space, exact results for the Bayes estimators of the mean life and the reliability function are obtained.     

Feasibility study of a grid connected photovoltaic system for the central region of Fiji

The paper also outlines the many aspects of grid connected solar power system that makes it viable and economically attractive.     

Thirty years of a ban on the sale of noniodized salt: impact on iodine nutrition in children in Himachal Pradesh, India

BACKGROUND: A survey conducted by the central iodine-deficiency disorders team in Himachal Pradesh, a state in the goiter-endemic belt of India, revealed that 10 of its 12 districts have an endemic prevalence of goiter. The survey was conducted to provide health program managers data to determine whether it would be necessary to initiate intervention measures. OBJECTIVE: To assess the status of urinary iodine excretion and household salt iodization levels after three decades of a complete ban on the sale of noniodized salt in this goiter-endemic state in India as measured by assessment of urinary iodine excretion levels and iodine content of salt at the household level. METHODS: The guidelines recommended by WHO/ UNICEF/ICCIDD for a rapid assessment of salt iodization were adopted. In each of the 12 studied districts, all senior secondary schools were enlisted and one school was selected by using a random sampling procedure. Two hundred fifty children 11 to 18 years of age were included in the study. Urine samples were collected from a minimum of 170 children and analyzed using the wet digestion method. Salt samples were also collected from a minimum of 170 children and analyzed using the spot testing kit. RESULTS: All districts had a median urinary iodine excretion level > 200 microg/L and 82% of the families were consuming salt with an iodine content of 15 ppm or higher. CONCLUSIONS: The results of the present study high-light the successful implementation of the salt iodization program in the state of Himachal Pradesh. This positive impact may be due to the comprehensive strategy adopted by the state government to improve the quality of salt, development of an effective monitoring information system and effective information, education, and communication activities.     

Improving adjustment to chronic illness through strategic self-presentation: An experimental study on a renal dialysis unit.

Laboratory studies show that strategic self-presentations strongly influence private self-evaluations. The present study experimentally manipulated self-presentations of dialysis patients' coping skills in order to influence their adjustment. In all, 42 renal dialysis patients matched for diabetes, gender, and dialysis years were randomly assigned to 3 conditions; adjustment was assessed at baseline, post-intervention, and 1 month follow-up. Patients in a self-presentation condition selectively presented themselves as successful copers in a videotaped interview, ostensibly as part of a training program for new patients. Patients in a problem disclosure condition discussed problems with managing their illness. Control group patients viewed a medical videotape about adjusting to dialysis. Patients in the self-presentation condition reported better adjustment, fewer physical symptoms, and more coping skills I month later, compared with patients in the other 2 conditions. In addition, coping skills were shown to mediate the relationship between strategic self-presentation and adjustment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pressure-Temperature Degradation of Green Color in Broccoli Juice

Broccoli juice greenness was marginally affected by pressure at low temperatures (30-40°C). At 800 MPa and slightly higher temperatures (50-60°C), first-order degradation of green color was observed. The greenness loss was suggested to be due to chlorophyll-pheophytin conversion with no further pheophytin degradation. Pheophytin degraded further when higher temperatures (≥70°C) were combined with elevated (or atmospheric) pressures (0.1–850 MPa). At these conditions greenness loss could be modeled by two consecutive first-order degradation steps. Temperature dependency of the rate constants for both degradation steps could be described by the Arrhenius equation with activation energies increasing with pressure. However, their pressure dependency could not satisfactorily be described by the Eyring equation.