Power System Stability Improvement via TCSC Controller Employing a Multi-objective Strength Pareto Evolutionary Algorithm Approach

This paper focuses on multi-objective designing of multi-machine Thyristor Controlled Series Compensator (TCSC) using Strength Pareto Evolutionary Algorithm (SPEA). The TCSC parameters designing problem is converted to an optimization problem with the multi-objective function including the desired damping factor and the desired damping ratio of the power system modes, which is solved by a SPEA algorithm. The effectiveness of the proposed controller validates on a multi-machine power system over a wide range of loading conditions. The results of the proposed controller (SPEATCSC) are compared with the Genetic Algorithm (GA) based tuned TCSC through some operating conditions to demonstrate its superior efficiency

The correlation of ischemic risk factors with left main tract disease

Background : Left main tract disease (LMTD) has been found to be the most important single lesion for the assessment of prognosis in coronary arteries disease and accompanies grave clinical outcome. This survey was designed to determine the difference between ischemic risk factors and LMTD. Materials and Method : In a case-control study we reviewed the data of 7857 patients who had undergone coronary angiography in Tehran Heart Center, during 2003 and 2004. Based on angiography findings, the patients were categorized into 3 groups: normal coronary vessels (control group: 1316), coronary artery disease (CAD: 6221), and LMCA≥50% stenosis (LMTD: 320). Multivariate analysis was performed by logistic regression. Results: The mean age of patients was 57.56±10.22 years. LMTD was seen in 4.1% of cases. The frequency of well-known cardiovascular risk factors as well as opium addiction was significantly more in the patients with CAD than in the control group. Comparison of the CAD patients with and without LMTD showed that the patients with LMTD were older, with higher male predominance and hyperlipidemia history. Conclusion: Independent to other risk factors, opium addiction can be considered as a risk factor for CAD. The variables of age, male, gender and hyperlipidemia were correlated to LMTD. The combination of several risk factors increases the probability of LMTD

Zn 1−x_{1-x} 1 - x Ni x_x x Te semiconductor nanocrystals in transparent glass for optoelectronic device applications

Abstract Doping glass with semiconductors, particularly with nanostructured semiconductors, has attracted attention due to the large optical absorption cross-sections of the latter. Based on this property, Ni $$^{2+}$$ 2 + (5 wt%) doped phosphate glass and Zn $$_{1-x}$$ 1 - x Ni $$_x$$ x Te (x = 0.5, 1.0, 5.0 and 10.0 wt% of Ni $$^{2+}$$ 2 + ) nanocrystals (NCs) doped phosphate glasses (GCs) were prepared by fusion method and subsequent heat treatment. Influence of Ni $$^{2+}$$ 2 + on structural, thermo-optical and third-order nonlinear optical properties have been analysed through various spectroscopic characterizations. The XRD pattern of the glass (G) exhibits the amorphous nature of the host material while GCs exhibit not only amorphous halo but also the presence of quantum dots (QDs) or nanocrystals (NCs) phases. TEM analysis of the studied GCs samples confirm the presence of quantum dots (QDs) and bulk NCs with an average diameter of approximately 4.2 $${\pm }$$ ± 0.3 nm and 13.4 $${\pm }$$ ± 0.2 nm, respectively. Several phosphate groups were observed and reported from Raman and FTIR-ATR spectra. The absorption band positions confirmed that Ni $$^{2+}$$ 2 + ions resemble to the octahedral symmetry. The intensity of absorption band around 1352 nm ( $$^3$$ 3 T $${_1}$$ 1 (F) $$\rightarrow$$ → $$^3$$ 3 A $${_2}$$ 2 (F)) increased with the increase of Ni $$^{2+}$$ 2 + in GCs which is an indicative of the $$^{[6]}$$ [ 6 ] Ni $$^{2+}$$ 2 + coordination. The emission properties such as emission cross-sections ( $${\sigma }_{emi}$$ σ emi ) full width at half maxima (FWHM) for the $$^1$$ 1 T $${_2}$$ 2 (D) $$\rightarrow$$ → $$^3$$ 3 T $${_2}$$ 2 (F) (visible) and $$^3$$ 3 A $${_2}$$ 2 (F) $$\rightarrow$$ → $$^3$$ 3 T $${_1}$$ 1 (F) (near-infrared) emission transitions were reported. Among the glass-containing semiconductor nanocrystals (GCs), the emission cross-sections in GC4 sample (x = 10% of Ni $$^{2+}$$ 2 + ) are the largest for both the visible (11.88 $$\times$$ × 10 $$^{-18}$$ - 18 cm $$^2$$ 2 ) and infrared (0.98 $$\times$$ × 10 $$^{-20}$$ - 20 cm $$^2$$ 2 ) transitions. Thermal diffusivity (D), thermal conductivity (K) and temperature dependent optical path length change (ds/dT) were obtained through time-resolved thermal lens (TL) and thermal relaxation (TR) methods. The D and K parameters do not change significantly with increase of Ni $$^{2+}$$ 2 + ions (0.5–5%) in GCs. Nonlinear-refractive index and nonlinear absorption of the studied samples were also obtained using femtosecond Z-scan technique. The increase of nonlinear absorption coefficient ( $$\beta$$ β ) is observed from GC2 (2.53 $${\times }$$ × 10 $$^{-10}$$ - 10 cm/W) to GC4 (7.98 $${\times }$$ × 10 $$^{-10}$$ - 10 cm/W). The GC4, sample with 10 wt% of Ni $$^{2+}$$ 2 + , showed the lowest ds/dT (1.22 $$\times$$ × 10 $$^{-6}$$ - 6 K $$^{-1}$$ - 1 ) with good lasing (FOM and emission cross-sections) and nonlinear absorption properties suggesting that it can be a good candidate for visible-red emission light conversion in LED technology

All-cause mortality by age and gender based on coronary artery calcium scores.

AimsAlthough coronary artery calcium (CAC) has been established as a robust tool for predicting total mortality during intermediate follow-up, less is known about the long-term predictive value of CAC.Methods and resultsThis study included 13 092 asymptomatic patients without known cardiovascular disease who underwent a clinically indicated CAC scan. CAC was categorized as an Agatson score of 0, 1-99, 100-399, and ≥400. We used multivariable Cox proportional hazards to calculate adjusted hazard ratios (HRs) for mortality stratified by age (younger, intermediate, or older) and gender. The mean age of participants was 58 ± 11 years and 67% were men. During a median follow-up of 11.0 ± 3.2 years, there were 522 deaths (4.0%). Compared with CAC = 0, increasing CAC was associated with higher mortality rate: 1-99 [HR: 1.5, 95% confidence interval (95% CI): 1.1-2.1]; 100-399 (HR: 1.8, 95% CI: 1.3-2.5); ≥400 (HR: 2.6, 95% CI: 1.9-3.6). Relative risk according to CAC category did not differ between genders. The strongest associations between CAC and mortality were observed for young and intermediate age participants. Nonetheless, the mortality rate of the older patients with CAC = 0 was far lower than that of the general US population. CAC was more predictive of long-term (15 years) than intermediate-term (5 years) mortality for men [receiver operator characteristics (ROC): 0.723 vs. 0.702] and women (ROC: 0.69 vs. 0.65).ConclusionCAC is strongly associated with the long-term risk of mortality in young- and middle-aged men and women. In older patients, the long-term risk stratification of CAC is lower, due principally to increased mortality rate in patients with low calcium scores; however, even in the older patients, those with absent or low CAC are at a significantly lower risk of mortality compared with the general population

All-cause mortality by age and gender based on coronary artery calcium scores.

AimsAlthough coronary artery calcium (CAC) has been established as a robust tool for predicting total mortality during intermediate follow-up, less is known about the long-term predictive value of CAC.Methods and resultsThis study included 13 092 asymptomatic patients without known cardiovascular disease who underwent a clinically indicated CAC scan. CAC was categorized as an Agatson score of 0, 1-99, 100-399, and ≥400. We used multivariable Cox proportional hazards to calculate adjusted hazard ratios (HRs) for mortality stratified by age (younger, intermediate, or older) and gender. The mean age of participants was 58 ± 11 years and 67% were men. During a median follow-up of 11.0 ± 3.2 years, there were 522 deaths (4.0%). Compared with CAC = 0, increasing CAC was associated with higher mortality rate: 1-99 [HR: 1.5, 95% confidence interval (95% CI): 1.1-2.1]; 100-399 (HR: 1.8, 95% CI: 1.3-2.5); ≥400 (HR: 2.6, 95% CI: 1.9-3.6). Relative risk according to CAC category did not differ between genders. The strongest associations between CAC and mortality were observed for young and intermediate age participants. Nonetheless, the mortality rate of the older patients with CAC = 0 was far lower than that of the general US population. CAC was more predictive of long-term (15 years) than intermediate-term (5 years) mortality for men [receiver operator characteristics (ROC): 0.723 vs. 0.702] and women (ROC: 0.69 vs. 0.65).ConclusionCAC is strongly associated with the long-term risk of mortality in young- and middle-aged men and women. In older patients, the long-term risk stratification of CAC is lower, due principally to increased mortality rate in patients with low calcium scores; however, even in the older patients, those with absent or low CAC are at a significantly lower risk of mortality compared with the general population

Presence, Characteristics, and Volumes of Coronary Plaque Determined by Computed Tomography Angiography in Young Type 2 Diabetes Mellitus

Cardiovascular Aspects of Radiolog

The Cardiovascular Trial of the Testosterone Trials: rationale, design, and baseline data of a clinical trial using computed tomographic imaging to assess the progression of coronary atherosclerosis.

BackgroundData from prior studies have yielded inconsistent results on the association of serum testosterone levels with the risk for cardiovascular disease. There are no clinical trial data on the effects of testosterone replacement therapy on plaque progression.ObjectiveWe designed a study to investigate the effect of testosterone therapy on coronary artery plaque progression using serial coronary computed tomographic angiography (CCTA). In this paper, we describe the study design, methods, and characteristics of the study population.MethodsThe Cardiovascular Trial of the Testosterone Trials (TTrials; NCT00799617) is a double-blind, placebo-controlled trial of 1 year of testosterone therapy in men 65 years or older with clinical manifestations of androgen deficiency and unequivocally low serum testosterone concentrations (<275 ng/dl). CCTA performed at baseline and after 12 months of therapy will determine the effects of testosterone on the progression of the total volume of noncalcified plaques. All scans are evaluated at a central reading center by an investigator blinded to treatment assignment.ResultsA total of 165 men were enrolled. The average age is 71.1 years, and the average BMI is 30.7. About 9% of men had a history of myocardial infarction, 6% angina, and 10% coronary artery revascularization. A majority reported hypertension and/or high cholesterol; 31.8% reported diabetes. Total noncalcified plaque at baseline showed a slight but nonsignificant trend toward lower plaque volume with higher serum testosterone concentrations (P=0.12).ConclusionThe Cardiovascular Trial will test the hypothesis that testosterone therapy inhibits coronary plaque progression, as assessed by serial CCTA