93 research outputs found

    Wolf Search Algorithm for Solving Optimal Reactive Power Dispatch Problem

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    This paper presents a new bio-inspired heuristic optimization algorithm called the Wolf Search Algorithm (WSA) for solving the multi-objective reactive power dispatch problem. Wolf Search algorithm is a new bio – inspired heuristic algorithm which based on wolf preying behaviour. The way wolves search for food and survive by avoiding their enemies has been imitated to formulate the algorithm for solving the reactive power dispatches. And the speciality  of wolf is  possessing  both individual local searching ability and autonomous flocking movement and this special property has been utilized to formulate the search algorithm .The proposed (WSA) algorithm has been tested on standard IEEE 30 bus test system and simulation results shows clearly about the good performance of the proposed algorithm

    Reduction of Real Power Loss and Safeguarding of Voltage Constancy by Artificial Immune System Algorithm

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    In this paper, Artificial Immune System (AIS) algorithm is used for solving reactive power problem. Artificial Immune System Algorithm, also termed as the machine learning approach to Artificial Intelligence, are powerful stochastic optimization techniques with potential features of random search, hill climbing, statistical sampling and competition. Artificial immune system algorithmic approach to power system optimization these ideas are embedded into proposed algorithm for solving reactive dispatch problem. In order to evaluate the proposed algorithm, it has been tested in standard IEEE 30,118 bus systems and compared to other specified algorithms. Simulation results show better performance of the proposed AIS algorithm in reducing the real power loss and preservation of voltage stability

    Optimal Power Flow using Ant Colony Search Algorithm to Evaluate Load Curtailment Incorporating Voltage Stability Margin Criterion

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    This paper proposes a method to compute load curtailment evaluation using ACSA based optimal power flow incorporating voltage stability margin criterion. . In a deregulated environment, congestion alleviation could mean load curtailment in certain situations.  The utilities would definitely prefer to curtail a load as lower as possible during a viability crisis situation. A criterion based on the voltage stability indicator is them incorporated as an additional constraint into the optimal power flow using ACSA algorithm and it is evaluated in a WSCC 9-bus test system.DOI:http://dx.doi.org/10.11591/ijece.v3i5.2738  

    Rapid Particle Swarm Optimization Algorithm for Solving Optimal Reactive Power Dispatch Problem

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    In this paper Rapid Particle Swarm Optimization (RPSO) algorithm is proposed to solve the optimal    reactive    power     dispatch Problem. The Rapid Particle swarm Optimization (RPSO) algorithm is obtained by merging PSO with Cauchy mutation. Basic idea is to introduce the Cauchy mutation into PSO such that it prevents PSO from trapping into a local optimum through stretched jumps made by the Cauchy mutation. In order to evaluate the efficiency of the proposed algorithm, it has been tested on IEEE 30 bus system and compared other standard algorithms. Results show’s that RPSO is more efficient in reducing the real power loss and voltage index also improved

    Study Of Mechanical Properties Of Aluminium Lm25 Using Stir Casting Method

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    The present study deals with the behaviour of aluminium hybrid alloy based composites, reinforced with fly ashnbsp particles and solid lubricants such as activated carbon .The first one of the composites consists of Al. with fly ash particlesnbsp and activated carbon. The other composite has Al with fly ash and solid lubricant: activated carbon at solid state. Both composites are fabricated through lsquoStir Casting Methodrsquo. Mechanical properties of the samples are measured by usual methods such as Hardness,Tensile .The tested samples are examined using Scanning Electron microscope (SEM) for the characterization of microstructure on the surface of composites. The Main Aim is to be results of the proposed Hybrid composites are compared with Al based metal matrix composites at corresponding values of test parameters

    Presentation and Treatment Outcomes of Liberian Children Age 5 Years and Under Diagnosed With Severe Malaria

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    Malaria is endemic in Liberia with a prevalence rate of up to 60% in some regions, and it has been a major cause of death in children under 5 years of age. Prior to the recent Ebola epidemic, we undertook a prospective, hospital-based pilot study at the National Referral Hospital in Monrovia, to characterize the presentation, accuracy of diagnosis, and treatment outcomes of children presenting for treatment of malaria. From June 2013 to May 2014, we recruited children 5 years and under who presented to the JFK Medical Center with suspected malaria. We collected both clinical and laboratory data on admission and on discharge. We enrolled 477 patients with an average age of 1.6 years. Demographic factors associated with testing negative for malaria included regular bed net use and prior treatment for malaria. The most common presenting symptoms of severe malaria in this population were headache and seizures. Of 246 patients admitted and treated for severe malaria, 33% tested negative by rapid diagnostic test and blood smear for malaria. The case fatality rate was higher for the patients who tested negative for malaria (4.9%) versus those who tested positive (0.6%). Three children who tested negative for malaria showed evidence of undiagnosed Salmonella typhi infection. These results suggest that malaria may be overdiagnosed and that the diagnoses of other infectious diseases, which present in a similar fashion, may be neglected. These findings underscore the need to develop rapid diagnostic tests to screen for alternative causes of febrile illness

    Enhanced Antifibrinolytic Efficacy of a Plasmin-Specific Kunitz-Inhibitor (60-Residue Y11T/L17R with C-Terminal IEK) of Human Tissue Factor Pathway Inhibitor Type-2 Domain1

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    Current antifibrinolytic agents reduce blood loss by inhibiting plasmin active sites (e.g., aprotinin) or by preventing plasminogen/tissue plasminogen activator (tPA) binding to fibrin clots (e.g., ε-aminocaproic acid and tranexamic acid); however, they have adverse side effects. Here, we expressed 60-residue (NH2NAE . . . IEKCOOH) Kunitz domain1 (KD1) mutants of human tissue factor pathway inhibitor type-2 that inhibit plasmin as well as plasminogen activation. A single (KD1-L17R-KCOOH) and a double mutant (KD1-Y11T/L17R- KCOOH) were expressed in Escherichia coli as His-tagged constructs, each with enterokinase cleavage sites. KD1-Y11T/L17R-KCOOH was also expressed in Pichia pastoris. KD1-Y11T/L17R-KCOOH inhibited plasmin comparably to aprotinin and bound to the kringle domains of plasminogen/plasmin and tPA with Kd of ~50 nM and ~35 nM, respectively. Importantly, compared to aprotinin, KD1-L17R-KCOOH and KD1-Y11T/L17R-KCOOH did not inhibit kallikrein. Moreover, the antifibrinolytic potential of KD1-Y11T/L17R-KCOOH was better than that of KD1-L17R-KCOOH and similar to that of aprotinin in plasma clot-lysis assays. In thromboelastography experiments, KD1-Y11T/L17R-KCOOH was shown to inhibit fibrinolysis in a dose dependent manner and was comparable to aprotinin at a higher concentration. Further, KD1-Y11T/L17R-KCOOH did not induce cytotoxicity in primary human endothelial cells or fibroblasts. We conclude that KD1-Y11T/L17R-KCOOH is comparable to aprotinin, the most potent known inhibitor of plasmin and can be produced in large amounts using Pichia

    Household air pollution and blood pressure, vascular damage and sub-clinical indicators of cardiovascular disease in older Chinese adults

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    Background Limited data suggest that household air pollution from cooking and heating with solid fuel (i.e., coal and biomass) stoves may contribute to the development of hypertension and vascular damage. Methods Using mixed-effects regression models, we investigated the associations of household air pollution with blood pressure (BP) and vascular function in 753 adults (ages 40-79y) from three diverse provinces in China. We conducted repeated measures of participants’ household fuel use, personal exposure to fine particulate air pollution (PM2.5), BP, brachial-femoral pulse wave velocity (bfPWV), and augmentation index. Ultrasound images of the carotid arteries were obtained to assess intima-media thickness (CIMT) and plaques. Covariate information on socio-demographics, health behaviors, 24-h urinary sodium, and blood lipids was also obtained. Results Average estimated yearly personal exposure to PM2.5 was 97.5 μg/m 3 (SD: 79.2; range: 3.5-1241), and 65% of participants cooked with solid fuel. In multivariable models, current solid fuel use was associated with higher systolic (2.4 mmHg, 95%CI: -0.4, 4.9) and diastolic BP (1.4 mmHg, 95%CI: -0.1, 3.0) and greater total area of plaques (1.7 mm 2, 95%CI: -6.5, 9.8) compared with exclusive use of electricity or gas stoves. A 1-ln(µg/m 3) increase in PM2.5 exposure was associated with higher systolic (1.5 mmHg, 95%CI: 0.2, 2.7) and diastolic BP (1.0 mmHg, 95%CI: 0.4, 1.7) and with greater CIMT (0.02 mm, 95%CI: 0.00, 0.04) and total area of plaques (4.7 mm 2, 95%CI: -2.0, 11.5). We did not find associations with arterial stiffness, except for a lower bfPWV (-1.5 m/s, 95%CI: -3.0, -0.0) among users of solid fuel heaters. Conclusions These findings add to limited evidence that household air pollution is associated with higher BP and with greater CIMT and total plaque area

    Differences in physical activity domains, guideline adherence, and weight history between metabolically healthy and metabolically abnormal obese adults: a cross-sectional study

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    BACKGROUND: Despite the accepted health consequences of obesity, emerging research suggests that a significant segment of adults with obesity are metabolically healthy (MHO). To date, MHO individuals have been shown to have higher levels of physical activity (PA), but little is known about the importance of PA domains or the influence of weight history compared to their metabolically abnormal (MAO) counterpart. OBJECTIVE: To evaluate the relationship between PA domains, PA guideline adherence, and weight history on MHO. METHODS: Pooled cycles of the National Health and Nutritional Examination Survey (NHANES) 1999–2006 (≥20 y; BMI ≥ 30 kg/m(2); N = 2,753) and harmonized criteria for metabolic syndrome (MetS) were used. Participants were categorized as “inactive” (no reported PA), “somewhat active” (>0 to < 500 metabolic equivalent (MET) min/week), and “active” (PA guideline adherence, ≥ 500 MET min/week) according to each domain of PA (total, recreational, transportation and household). Logistic and multinomial regressions were modelled for MHO and analyses were adjusted for age, sex, education, ethnicity, income, smoking and alcohol intake. RESULTS: Compared to MAO, MHO participants were younger, had lower BMI, and were more likely to be classified as active according to their total and recreational PA level. Based on total PA levels, individuals who were active had a 70 % greater likelihood of having the MHO phenotype (OR = 1.70, 95 % CI: 1.19–2.43); however, once stratified by age (20–44 y; 45–59 y; and; ≥60 y), the association remained significant only amongst those aged 45–59 y. Although moderate and vigorous PA were inconsistently related to MHO following adjustment for covariates, losing ≥30 kg in the last 10 y and not gaining ≥10 kg since age 25 y were significant predictors of MHO phenotype for all PA domains, even if adherence to the PA guidelines were not met. CONCLUSION: Although PA is associated with MHO, the beneficial effects of PA may be moderated by longer-term changes in weight. Longitudinal analysis of physical activity and weight change trajectories are necessary to isolate the contribution of duration of obesity, PA behaviours, and longer-term outcomes amongst MHO individuals
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