Synchronous machine parameters estimation using a new genetic‐based algorithm

A new genetic‐based algorithm (GA) for estimating synchronous machine parameters from frequency tests is presented in this paper. GAs are general search techniques based on biological concepts and are very suitable for solving optimization problems. The proposed method uses a set of digital measurements for the direct axis impedance magnitude and phase as functions of frequency for estimating both the d‐ and q‐axis parameters, such as direct reactance and time constants. The problem is formulated as an optimization problem and solved using the proposed method. Two different models along with different fitness functions are suggested to be used with the genetic algorithm. A practical example from the literature is used to test the proposed algorithm. The results obtained are compared with those given in the literature using other methods. The results and comparison show that the new algorithm is very applicable and highly accurate. Copyright © 1999 John Wiley and Sons, Ltd.     

Effect of date seeds on oxidative damage and antioxidant status in vivo

BACKGROUND: Date seeds have been shown to contain high amounts of antioxidants. However, in vivo studies on date seeds are lacking. Therefore the purpose of this study was to determine the effect of date seeds on oxidative damage and antioxidant status in vivo. Male Wistar rats were fed a basal diet containing 0, 70 or 140 g kg^?1 date seeds for 30 days. All three diets were isonitrogenous and isocaloric. Indication of oxidative damage was assessed in the liver and serum, and antioxidant status was assessed in the liver. Serum biochemical parameters, including indicators of tissue cellular damage and complete blood count with differential, were also determined. RESULTS: The results showed that date seeds significantly (P < 0.05) reduced liver and serum malondialdehyde (a lipid peroxidative damage product) and serum lactate dehydrogenase and creatine kinase. Liver antioxidants (vitamin E, vitamin C, glutathione, superoxide dismutase, glutathione peroxidase and catalase), complete blood count with differential and other serum biochemical parameters assessed were not significantly altered by date seeds. CONCLUSION: The results obtained suggest a protective effect of date seeds against in vivo oxidative damage, possibly through the action of their bioactive antioxidants. Copyright © 2011 Society of Chemical Industry     

A STUDY OF THE NITRIC ACID OXIDATION OF PETROLEUM ASPHALTENES.

Petroleum asphaltenes have been subjected to progressive oxidation using 70% nitric acid, and the reaction products monitored by elemental analysis. Gas chromatographic-mass spectroscopic (gc-IIs) analysis of products from exhaustive oxidation has also been carried out. The oxidation of asphaltenes rapidly produces both water-soluble and water-insoluble oxygen rich species, some of which can be attributed to products of an aromatic nitration reaction. Massive degradation, in the course of which material is steadily converted to water soluble products, continues with prolonged reaction time. The widespread formation of carboxylic acids accounts only in part for the large oxygen uptake, and the gc-ms evidence suggests that a number of other oxygenated structures, in which carbonyl and hydroxyl groups are likely to be most important, are formed as stable intermediates.     

A GPU-based genetic algorithm for the p-median problem

The p-median problem is a well-known NP-hard problem. Many heuristics have been proposed in the literature for this problem. In this paper, we exploit a GPGPU parallel computing platform to present a new genetic algorithm implemented in CUDA and based on a pseudo-Boolean formulation of the p-median problem. We have tested the effectiveness of our algorithm using a Tesla K40 (2880 CUDA cores) on 290 different benchmark instances obtained from OR-Library, discrete location problems benchmark library, and benchmarks introduced in recent publications. The algorithm succeeded in finding optimal solutions for all instances except for two OR-library instances, namely pmed 30 and pmed 40, where better than 99.9% approximations were obtained.     

Distances in random digital search trees

Distances between nodes in random trees is a popular topic, and several classes of trees have recently been investigated. We look into this matter in digital search trees. By analytic techniques, such as the Mellin Transform and poissonization, we describe a program to determine the moments of these distances. The program is illustrated on the mean and variance. One encounters delayed Mellin transform equations, which we solve by inspection. In addition to various asymptotics, we give an exact expression for the mean and for the variance in the unbiased case. Interestingly, the unbiased case gives a bounded variance, whereas the biased case gives a variance growing with the number of keys. It is therefore possible in the biased case to show that an appropriately normalized version of the distance converges to a limit. The complexity of moment calculation increases substantially with each higher moment; it is prudent to seek a shortcut to the limit via a method that avoids the computation of all moments. Toward this end, we utilize the contraction method to show that in biased digital search trees the distribution of a suitably normalized version of the distances approaches a limit that is the fixed-point solution of a distributional equation (distances being measured in the Wasserstein metric space). An explicit solution to the fixed-point equation is readily demonstrated to be Gaussian.     

Fuzzy Based Decision Making Approach for Evaluating the Severity of COVID-19 Pandemic in Cities of Kingdom of Saudi Arabia

The World Health Organization declared COVID-19 a pandemic on March 11, 2020 stating that it is a worldwide danger and requires imminent preventive strategies to minimise the loss of lives. COVID-19 has now affected millions across 211 countries in the world and the numbers continue to rise. The information discharged by the WHO till June 15, 2020 reports 8,063,990 cases of COVID-19. As the world thinks about the lethal malady for which there is yet no immunization or a predefined course of drug, the nations are relentlessly working at the most ideal preventive systems to contain the infection. The Kingdom of Saudi Arabia (KSA) is additionally combating with the COVID-19 danger as the cases announced till June 15, 2020 reached the count of 132,048 with 1,011 deaths. According to the report released by the KSA on June 14, 2020, more than 4,000 cases of COVID-19 pandemic had been registered in the country. Tending to the impending requirement for successful preventive instruments to stem the fatalities caused by the disease, our examination expects to assess the severity of COVID-19 pandemic in cities of KSA. In addition, computational model for evaluating the severity of COVID-19 with the perspective of social influence factor is necessary for controlling the disease. Furthermore, a quantitative evaluation of severity associated with specific regions and cities of KSA would be a more effective reference for the healthcare sector in Saudi Arabia. Further, this paper has taken the Fuzzy Analytic Hierarchy Process (AHP) technique for quantitatively assessing the severity of COVID-19 pandemic in cities of KSA. The discoveries and the proposed structure would be a practical, expeditious and exceptionally precise evaluation system for assessing the severity of the pandemic in the cities of KSA. Hence these urban zones clearly emerge as the COVID-19 hotspots. The cities require suggestive measures of health organizations that must be introduced on a war footing basis to counter the pandemic. The analysis tabulated in our study will assist in mapping the rules and building a systematic structure that is immediate need in the cities with high severity levels due to the pandemic.     

Enhanced the optical,electrical, and shielding properties of some alkali-borate glasses doped with lanthanide cerium oxide,CeO2

Sodium borate glass doped with cerium oxide, 0–10 wt%, has been prepared based on the quenching method from the melting point. The XRD, DSC, FTIR, and UV–Vis are used to study the structure, thermal, optical properties and shielding attenuation of the studied materials. XRD analysis showed that the as-prepared samples are amorphous in nature. Increased CeO₂ content in the glassy matrix led to an increase in the glass stability, the dielectric constant value, as well as the optical transparency. The measured shielding parameters of the present study revealed that the glass system containing 10 wt% of CeO₂ exhibits the better photon shielding performance than the glass of 0 wt% CeO₂. Cerium-rich glass showed the highest resistance for both gamma-ray and the fast neutrons among all the present samples. The removal cross-sections varied from between 89?×?10^–3 cm^?1, for the cerium-free sample, and 97?×?10^–3 cm^?1 for cerium-rich sample. Such observation may nominated Ce-rich glass to be used in some shielding and attenuation applications, especially for gamma-ray and fast neutrons applications.

     

Facile synthesis of silver nanoparticles mediated by polyacrylamide‐reduction approach to antibacterial application

The current time increase in the prevalence of antibiotic resistant ‘super‐bugs’ and the risks associated with food safety have become global issues. Therefore, further research is warranted to identify new and effective antimicrobial substances. Silver nanoparticles (Ag‐NPs) were synthesized by autoclaving technique using, different concentrations of Ag salt (AgNO₃) solution (1, 5, 10, and 25 mM). Their presence was confirmed by a surface plasmon resonance band at ∼435 nm using UV–Vis absorption spectra. The morphology of the synthesized Ag‐NPs stabilized by polyacrylamide (PAM) was examined by TEM, SAED, and EDS. TEM images revealed that the synthesized Ag‐NPs had an average diameter of 2.98±0.08 nm and SAED and EDS results confirmed the formation of Ag‐NPs. In addition, FT‐IR spectroscopy revealed that a PAM polymer matrix stabilized the Ag‐NPs. The well diffusion method, was used to test, Gram positive and Gram negative bacteria were examined. Also the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were studied against Ag‐NPs. The Ag‐NPs exhibited strong inhibitory activity, MIC and MBC against the tested clinical bacterial isolates. These results suggest that Ag‐NPs stabilized in PAM are highly effective against clinical bacterial isolates can be applied in medical fields.Inspec keywords: antibacterial activity, silver, nanoparticles, nanomedicine, surface plasmon resonance, X‐ray chemical analysis, transmission electron microscopy, electron diffraction, Fourier transform infrared spectroscopy, microorganisms, ultraviolet spectra, visible spectraOther keywords: Ag‐NP facile synthesis, PAM‐reduction approach, antibacterial application, antibiotic resistant super‐bugs, food safety, antimicrobial agents, antibiotics, antimicrobial substances, Ag salt solution concentration, ultraviolet‐visible absorption spectra, polyacrylamide, transmission electron microscopy, electron diffraction, energy dispersive X‐ray spectroscopy, TEM images, Fourier transform infrared spectroscopy, PAM polymer matrix, diffusion method, Gram positive bacteria, Gram negative bacteria, clinical bacterial isolates, Ag     

Deformation and densification behaviours of nickel-based superalloy during hot isostatic pressing

Hot isostatic pressing of nickel-based superalloys has important applications for manufacturing near-net shape parts such as turbine disks and jet engine parts, which have to operate at high temperatures. Finite element modelling can be used to predict deformation and densification behaviour of such superalloys. Thus, the cost and time of trial and error to obtain the required geometry of the part can be reduced, such that near-net shape parts can be manufactured more economically. Numerical simulations were carried out by implementing the model of ElRakayby and Kim into Abaqus-FEA. The model parameters (relative density functions f and c) for the nickel-based superalloy were obtained from the creep response and compressive strength of porous and solid powder compacts at high a temperature. The agreement between finite element calculations and the experimental data was good for densification, shape change and density distribution of nickel-based superalloy during hot isostatic pressing.     

Limit laws for terminal nodes in random circuits with restricted fan-out: a family of graphs generalizing binary search trees

We introduce a family of graphs C(n,i,s,a) that generalizes the binary search tree. The graphs represent logic circuits with fan-in i, restricted fan-out s, and arising by n progressive additions of random gates to a starting circuit of a isolated nodes. We show via martingales that a suitably normalized version of the number of terminal nodes in binary circuits converges in distribution to a normal random variate.Received: 23 July 2003, Published online: 29 October 2004