Optimal load distribution between units in a power plant

This paper presents a strategy for load distribution between the generating units in hydro power plants. The objective is to reach the maximum energy conversion efficiency for a given dispatched power. The developed tool employs a heuristic-based combinatorial optimization technique in conjunction with a set of system variables measurement allowing real-time load sharing. The developed equipment is used to give online energy conversion efficiency from each unit of the power plant. No specific previous information about the efficiency of system components is required. Simulation results of the proposed optimization technique when applied to typical hydro power plant data are presented.     

Comparison between nonconforming movement methods

In this work, we compare two nonconforming movement techniques: the mortar element method and the Lagrange multipliers. We present a unified formulation that can be easily used for electrical machines analysis. The anti-periodicity conditions as well as the use of high-order interface are discussed. The obtained linear systems are compared and results are shown for a permanent magnet machine.     

Postoperative mortality in infective endocarditis: determinant factors

OBJECTIVE: It has been shown recently that 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) is expressed as at least 2 isozymes. In the liver, 11 beta-HSD1 converts cortisone to cortisol; in the kidney, 11 beta-HSD2 converts cortisol to cortisone. Conventional assessment of 11 beta-HSD activity in vivo has relied on gas chromatographic measurement of the ratios of conjugated cortisol and cortisone metabolites. However, these do not permit distinction between the tissue-specific activities of the enzymes and do not reflect all forms of 11 beta-HSD deficiency. In this report, we have assessed the usefulness of measuring unconjugated cortisol metabolites and free cortisol and cortisone in urine as indices of renal 11 beta-HSD activity in man. DESIGN: Six healthy male subjects established in sodium balance were given either glycyrrhetinic acid (170 mg t.d.s., to inhibit 11 beta-HSD2), carbenoxolone (100 mg t.d.s., to inhibit both 11 beta-HSD1 and 11 beta- HSD2) or both inhibitors in combination. MEASUREMENTS: Urinary electrolytes were measured and the concentrations of total and unconjugated urinary cortisol and its metabolites were determined by gas chromatography mass spectrometry. RESULTS: Glycyrrhetinic acid and carbenoxolone inhibited renal 11 beta-HSD2 to a similar degree, as judged by similar sodium retention. As previously reported, conventional measurement of ratios of total cortisol to cortisone metabolites were influenced to a greater extent by glycyrrhetinic acid (100-200% increase in ratio from baseline) than by carbenoxolone (< 30% increase). However, the effect of carbenoxolone was readily detected by measurement of urinary unconjugated cortisol/cortisone (130-480% increase of ratio from baseline) and also by measurement of ratios of unconjugated cortisol metabolites (60-130% increase). CONCLUSIONS: Measurement of free cortisol and cortisone in urine provides the most sensitive index of renal 11 beta-HSD activity. Measurement of total and conjugated urinary steroids is insensitive in circumstances where 11 beta-HSD activity in liver or elsewhere may be abnormal.     

Multifunctional carbon-nanotube cellular endoscopes

Glass micropipettes, atomic force microscope tips and nanoneedles can be used to interrogate cells, but these devices either have conical geometries that can damage cells during penetration or are incapable of continuous fluid handling. Here, we report a carbon-nanotube-based endoscope for interrogating cells, transporting fluids and performing optical and electrochemical diagnostics at the single organelle level. The endoscope, which is made by placing a multiwalled carbon nanotube (length, 50-60?μm) at the tip of a glass pipette, can probe the intracellular environment with a spatial resolution of ～100?nm and can also access organelles without disrupting the cell. When the nanotube is filled with magnetic nanoparticles, the endoscope can be remotely manoeuvered to transport nanoparticles and attolitre volumes of fluids to and from precise locations. Because they are mounted on conventional glass micropipettes, the endoscopes readily fit standard instruments, creating a broad range of opportunities for minimally invasive intracellular probing, drug delivery and single-cell surgery.     

Thermal explosions resulting from fuel-coolant interactions: Analysis of single bubble hydrodynamics

High-speed photographic data and pressure traces of thermal explosions from the contact of single drops of iron oxide with water were analyzed according to models describing underwater chemical explosion and cavitation bubbles. The objective of the study was to develop a simple method for analyzing the microscale hydrodynamics of fuel-coolant interactions (FCI). We have found that for a given external pressure and liquid density essentially all the features of the radial motion of the explosion bubble, including the total energy release, are uniquely determined by a single parameter—the bubble period. Nearly all of the heat transfer from fuel to coolant occurs during the 10^?5 to 10^?4 sec timespan of coolant vapor film collapse during which the fuel fragments. The observable features of the resulting explosion bubble are not significantly affected by the degree of heat transfer from vapor to coolant liquid and the bubble can be modeled as an empty cavity. The method developed during this study should facilitate investigations on FCI by simplifying the analyses of thermal explosion data. Further attention can be given to experiments on the effects of fuel parameters,e.g., surface tension and viscosity, on fragmentation, heat transfer, and explosive yield.     

Dystrophia myotonica

The authors present two cases of myotonic dystrophy (Steinert's disease) with cardiac involvement in young adults. They point out the rareness of this disease, the multisystemic involvement and also the diagnostic problems in the absence of the classic clinical picture.     

Glasgow Coma Scale score in the evaluation of outcome in the intensive care unit: findings from the Acute Physiology and Chronic Health Evaluation III study

OBJECTIVE: To investigate the ability of the Glasgow Coma Scale score to predict hospital mortality rate for adult medical-surgical intensive care unit (ICU) patients without trauma. DESIGN: A prospective cohort analysis of adult medical-surgical patients from a nationally representative sample of 40 U.S. hospitals. PATIENTS: 15,973 consecutive, nontraumatic ICU admissions and a comparison group of 687 head trauma admissions. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients' gender, age, treatment location before ICU admission, comorbidities, admission diagnosis, daily physiologic measurements, Glasgow Coma Scale score, Acute Physiology and Chronic Health Evaluation (APACHE III) score, subsequent hospital mortality rate, and unit-specific sedation practices were noted. Hospital mortality rates were stratified by the first ICU day Glasgow Coma Scale score for all admissions. The relationship between the Glasgow Coma Scale score and outcome for two high mortality medical diagnoses (post-cardiac arrest and sepsis) were also examined and compared to the relationship found in patients with head trauma. The Glasgow Coma Scale score on ICU admission had a highly significant (r2 = .922, p < .0001) but nonlinear relationship with subsequent outcome in ICU patients without trauma. Discrimination of patients into high- or low-risk prognostic groups was good, but discrimination in the intermediate levels (Glasgow Coma Scale score of 7 to 11) was reduced. This relationship varied within the operative and nonoperative groups, and also within different disease categories, various age groups, and certain ranges of the Glasgow Coma Scale score. A reduced initial Glasgow Coma Scale score associated with sepsis was a combination of factors associated with a higher mortality rate than that found in patients with head trauma. The proportion of patients who could not be assigned a Glasgow Coma Scale score because of sedation/paralysis varied widely across ICUs. The overall predictive capability of the APACHE III Prognostic Scoring System was improved by incorporating the Glasgow Coma Scale score. CONCLUSIONS: We demonstrated the prognostic importance of admission levels of consciousness as measured by the Glasgow Coma Scale score on ICU and hospital mortality rates. We concluded that the Glasgow Coma Scale score may be used to stratify and predict mortality risk in general intensive care patients, but lack of sensitivity in the intermediate range of Glasgow Coma Scale Score should be noted. Ideally, the Glasgow Coma Scale score should also be applied in the context of other physiologic information and the patient's specific diagnosis. Variation in the use of sedatives in different ICUs means that imputing or substituting a value other than normal for an unobtainable Glasgow Coma Scale score may introduce a substantial treatment bias into subsequent outcome predictions.     

Electrochemical and analytical study of corrosion inhibition on carbon steel in HCl medium by 1,12-bis(1,2,4-triazolyl)dodecane

1,12-bis(1,2,4-triazolyl)dodecane (dTC12) is an excellent corrosion inhibitor for carbon steel in deaerated 1 M HCl solution. In this work electrochemical and analytical techniques were used to study the inhibition of corrosion on carbon steel in acidic medium. The carbon steel corrosion inhibition of dTC12 was attributed to the synergistic effect between chloride anion and quaternary ammonium ion. The protective efficiency of the film was higher than 90%, indicating that corrosion of carbon steel in 1 M HCl is reduced by dTC12.The effect of dissolved oxygen on the inhibition efficiency was also investigated. The results show that the inhibition efficiency increases in early stage and decreases for a long immersion time.