Formation of a strategy for energy development and utilization withpower electronic conversion technologies: a southeast USA regionalapproach

Key issues for design and research needs in power electronic conversion technologies as applied to energy development and utilization are presented. The analysis is geared for the southeast region of the United States, but the information can be of use to firms and universities in other regions of the country seeking guidance in this area. The technical background and a project justification in terms of applications and utilization of power electronic based conversion technologies are presented. The author examines the research issues identified in power quality, energy efficiency, and controls. The research approach developed to address the identified research is discussed     

Watthour meter accuracy under controlled unbalanced harmonicvoltage and current conditions

This work presents the results of phase I of the project on the accuracy of watthour meters when subjected to closely-duplicated real-world unbalanced harmonic voltage and current conditions. Such real-world conditions involved differences in voltage and current magnitudes as well as differences in the voltage and current total harmonic distortion levels of each phase. Tests were performed on a selected sample of nine three-phase and three single-phase watthour meters. Some results showed that under a particular set of unbalanced waveforms with harmonic conditions of I_THD>80% and V_THD>2%, the percentage errors exhibited by these meters ranged from -10.09% to +0.52%     

Using constraints and their value for optimization of large ODE systems

We provide analytical tools to facilitate a rigorous assessment of the quality and value of the fit of a complex model to data. We use this to provide approaches to model fitting, parameter estimation, the design of optimization functions and experimental optimization. This is in the context where multiple constraints are used to select or optimize a large model defined by differential equations. We illustrate the approach using models of circadian clocks and the NF-κB signalling system.     

The involvement of oxidative stress in ochratoxin A and fumonisin B1 toxicity in rats

The aim of this study was to find out whether very low doses of nephrotoxic and hepatotoxic mycotoxins ochratoxin A (OTA) and fumonisin B1 (FB1) induce oxidative stress in rat kidney and liver and whether their effect is synergistic. Rats were treated orally with OTA (5 ng/kg b.w. and 50 microg/kg b.w.) and FB1 (200 ng/kg b.w. and 50 microg/kg b.w.), or their combinations. Malondialdehyde (MDA) and protein carbonyls (PCs) concentration in kidney was affected with lower dose of OTA than in liver (p<0.05). FB1 did not affect MDA and PCs concentrations in the liver, while in the kidney both FB1 doses increased MDA concentration (p<0.05). The combination of the lower doses of OTA+FB1 increased the MDA and PCs concentration both in the liver and the kidney, compared to controls and animals treated with respective doses of mycotoxins (p<0.05). The combinations of mycotoxins reduced the catalase activity only in the kidney when compared to controls (p<0.05). In contrast to the increased kidney concentrations of MDA and PCs even with very low doses of OTA and FB1, the activity of catalase and SOD does not change. Combinations of OTA+FB1 affected almost all parameters, which indicates their potential to produce oxidative damage.     

Evaluation of MALDI-TOF/MS Technology in Olive Oil Adulteration

Adulteration of extra virgin olive oil (EVOO) by addition of other vegetable oils or lower-grade olive oils is a common problem of the oil market worldwide. Therefore, we developed a fast protocol for detection of EVOO adulteration by mass spectrometry fingerprinting of triacylglycerol (TAG) profiles based on MALDI-TOF/MS. For that purpose, EVOO TAG profiles were compared with those of edible sunflower oil and olive oil composed of refined olive oil and virgin olive oils. Adulteration of EVOO was simulated by addition of sunflower and mixture of refined olive oil and virgin olive oils at 1, 10 and 20% w/w. Results of mass spectrometry TAG profiling were compared with routinely assessed K values for identification of adulteration. MALDI-TOF/MS technology coupled with statistical analysis was proven as useful for detection of adulteration in EVOO at a rate down to 1%. In contrast, standard spectrophotometric methods failed to identify minor adulterations. In addition, the ability of MALDI-TOF/MS in detection of adulteration was tested on EVOO samples from different geographical regions. Results demonstrated that MALDI-TOF/MS technology coupled with statistical analysis is able to distinguish adulterated oils from other EVOO.     

The Mystery of Diabetic Cardiomyopathy: From Early Concepts and Underlying Mechanisms to Novel Therapeutic Possibilities

Diabetic patients are predisposed to diabetic cardiomyopathy, a specific form of cardiomyopathy which is characterized by the development of myocardial fibrosis, cardiomyocyte hypertrophy, and apoptosis that develops independently of concomitant macrovascular and microvascular diabetic complications. Its pathophysiology is multifactorial and poorly understood and no specific therapeutic guideline has yet been established. Diabetic cardiomyopathy is a challenging diagnosis, made after excluding other potential entities, treated with different pharmacotherapeutic agents targeting various pathophysiological pathways that need yet to be unraveled. It has great clinical importance as diabetes is a disease with pandemic proportions. This review focuses on the potential mechanisms contributing to this entity, diagnostic options, as well as on potential therapeutic interventions taking in consideration their clinical feasibility and limitations in everyday practice. Besides conventional therapies, we discuss novel therapeutic possibilities that have not yet been translated into clinical practice.     

Asynchronous interconnection of large-scale photovoltaic plants: site selection considerations

Large-scale penetration of photovoltaic (PV) energy in a distribution network requires careful planning of its location on the distribution network since it evidently demands large space, flexible maintenance access and exposure to driving energy sources such as sunlight for PV plants. Besides that, the technical aspects of the design should consider possible constraints that may introduce inefficiency in the generation or simply unexpected loss in the distribution. This paper addresses the decentralisation requirement for large-scale deployment of PV power sources as it resists the intermittency of the PV output naturally. In this study, a Monte Carlo method was used to justify the validity of this implication. A modified Gaussian distribution function was used to model the random fluctuations of the PV source and was used in the Monte Carlo simulation. The result shows considerable boost in the average power level and suppression of the fluctuation rate while the interconnected sources are uncorrelated.     

Development of a PC-based data acquisition system for performancemonitoring on an 81 megawatt steam cycle electric power generating unit

A computer-based performance monitoring system has been successfully developed and implemented on an 81 MW steam cycle generating unit. The instrument, data acquisition, computer, and software requirements for the system are discussed. This PC-based system was designed in such a manner that it is transparent to the unit's existing control scheme. Data from this system permits the setting of operating limits to avoid ongoing problems of turbine blade damage     

A study of polyphase watthour meter accuracy comparing single phaseseries to polyphase calibration

This paper examines the accuracy of polyphase watthour meters derived from two methods of calibration. The standard single phase series method is compared to the three phase method of calibrating polyphase transformer rated and self-contained induction type watthour meters. A total of seventy two meters from four different manufactures are tested. Sixty of these meters are tested at full load, full load with 0.5 lagging power factor and light load for each of the calibration methods. Twelve meters are further tested over a greater range of loading conditions. Also, the effect of rotating the phase of the input conductors on the meter's accuracy is examined     

Nonsinusoidal electrical measurement accuracy in adjustable-speedmotors and drives

Accurate measurements of voltage, current and power under nonsinusoidal conditions are essential for determining the efficiency of a drive system and performing separation of losses between an adjustable-speed drive (ASD) and an electric motor. That information is invaluable for equipment designers, manufacturers and users. Three modern power meters and analyzers were tested to determine their accuracy with various nonsinusoidal waveforms applied. The meters were subjected to waveforms that are characteristic to the three most common fractional and integral horsepower ASD technologies, namely, pulsewidth modulation induction, brushless DC and switched-reluctance drives. The tests were performed under field conditions and in a computer-controlled laboratory environment. The obtained results show that some meters are able to measure accurately electric power at the input to ASDs. However, the output power of ASDs for brushless DC and switched-reluctance technology was not measured with acceptable accuracy by any of the tested meters. Possible reasons of meters inaccuracies and suggestions for performance improvement are presented. Conclusions on the present state of ASD electric power measurements and recommendations for further research are given