Steady Flow over a Rotating Disk in Porous Medium with Heat Transfer

The steady flow of an incompressible viscous fluid above an infinite rotating disk in a porous medium is studied with heat transfer. Numerical solutions of the nonlinear governing equations which govern the hydrodynamics and energy transfer are obtained. The effect of the porosity of the medium on the velocity and temperature distributions is considered

Genetic Algorithm Based Control System Design of a Self-Excited Induction Generator

This paper presents an application of the genetic algorithm (GA) for optimizing controller gains of the Self-Excited Induction Generator (SEIG) driven by the Wind Energy Conversion Scheme (WECS). The proposed genetic algorithm is introduced to adapt the integral gains of the conventional controllers of the active and reactive control loop of the system under study, where GA calculates the optimum value for the gains of the variables based on the best dynamic performance and a domain search of the integral gains. The proposed genetic algorithm is used to regulate the terminal voltage or reactive power control, by adjusting the self excitation, and to control the mechanical input power or active power control by adapting the blade angle of WECS, in order to adjust the stator frequency. The GA is used for optimizing these gains, for an active and reactive power loop, by solving the related optimization problem. The simulation results show a better dynamic performance using the GA than using the conventional PI controller for active and reactive control

Optimization of Fuzzy Logic Controller for Supervisory Power System Stabilizers

This paper presents a powerful supervisory power system stabilizer (PSS) using an adaptive fuzzy logic controller driven by an adaptive fuzzy set (AFS). The system under study consists of two synchronous generators, each fitted with a PSS, which are connected via double transmission lines. Different types of PSS-controller techniques are considered. The proposed genetic adaptive fuzzy logic controller (GAFLC)-PSS, using 25 rules, is compared with a static fuzzy logic controller (SFLC) driven by a fixed fuzzy set (FFS) which has 49 rules. Both fuzzy logic controller (FLC) algorithms utilize the speed error and its rate of change as an input vector. The adaptive FLC algorithm uses a genetic algorithmto tune the parameters of the fuzzy set of each PSS. The FLC’s are simulated and tested when the system is subjected to different disturbances under a wide range of operating points. The proposed GAFLC using AFS reduced the computational time of the FLC, where the number of rules is reduced from 49 to 25 rules. In addition, the proposed adaptive FLC driven by a genetic algorithm also reduced the complexity of the fuzzy model, while achieving a good dynamic response of the system under study

Optimization of Fuzzy Logic Controller for Supervisory Power System Stabilizers

This paper presents a powerful supervisory power system stabilizer (PSS) using an adaptive fuzzy logic controller driven by an adaptive fuzzy set (AFS). The system under study consists of two synchronous generators, each fitted with a PSS, which are connected via double transmission lines. Different types of PSS-controller techniques are considered. The proposed genetic adaptive fuzzy logic controller (GAFLC)-PSS, using 25 rules, is compared with a static fuzzy logic controller (SFLC) driven by a fixed fuzzy set (FFS) which has 49 rules. Both fuzzy logic controller (FLC) algorithms utilize the speed error and its rate of change as an input vector. The adaptive FLC algorithm uses a genetic algorithmto tune the parameters of the fuzzy set of each PSS. The FLC’s are simulated and tested when the system is subjected to different disturbances under a wide range of operating points. The proposed GAFLC using AFS reduced the computational time of the FLC, where the number of rules is reduced from 49 to 25 rules. In addition, the proposed adaptive FLC driven by a genetic algorithm also reduced the complexity of the fuzzy model, while achieving a good dynamic response of the system under study

Kinetic Spectrophotometric Determination of Certain Cephalosporins in Pharmaceutical Formulations

A simple, reliable, and sensitive kinetic spectrophotometric method was developed for determination of eight cephalosporin antibiotics, namely, Cefotaxime sodium, Cephapirin sodium, Cephradine dihydrate, Cephalexin monohydrate, Ceftazidime pentahydrate, Cefazoline sodium, Ceftriaxone sodium, and Cefuroxime sodium. The method depends on oxidation of each of studied drugs with alkaline potassium permanganate. The reaction is followed spectrophotometrically by measuring the rate of change of absorbance at 610 nm. The initial rate and fixed time (at 3 minutes) methods are utilized for construction of calibration graphs to determine the concentration of the studied drugs. The calibration graphs are linear in the concentration ranges 5–15 μg mL−1 and 5–25 μg mL−1 using the initial rate and fixed time methods, respectively. The results are validated statistically and checked through recovery studies. The method has been successfully applied for the determination of the studied cephalosporins in commercial dosage forms. Statistical comparisons of the results with the reference methods show the excellent agreement and indicate no significant difference in accuracy and precision

Power System Stabilizer Driven by an Adaptive Fuzzy Set for Better Dynamic Performance

This paper presents a novel application of a fuzzy logic controller (FLC) driven by an adaptive fuzzy set (AFS) for a power system stabilizer (PSS).The proposed FLC, driven by AFS, is compared with a classical FLC, driven by a fixed fuzzy set (FFS). Both FLC algorithms use the speed error and its rate of change as input vectors. A single generator equipped with FLC-PSS and connected to an infinite bus bar through double transmission lines is considered. Both FLCs, using AFS and FFS, are simulated and tested when the system is subjected to different step changes in the reference value. The simulation results of the proposed FLC, using the adaptive fuzzy set, give a better dynamic response of the overall system by improving the damping coefficient and decreasing the rise time and settling time compared with classical FLC using FFS. The proposed FLC using AFS also reduces the computational time of the FLC as the number of rules is reduced.

Strukturna svojstva i UV – NIR apsorpcijski spektri bezmetalnih tankih slojeva ftalocijanina

The structural properties and absorption spectra of H2Pc thin films have been studied. The films used in these studies were thermally evaporated on glass/quartz substrates with thickness ranging from 60 to 460 nm. The XRD studies of H2Pc thin films showed that the as-deposited films have α-form with monoclinic system. The mean crystallite size (L), the dislocation density (δ) and the strain (ξ) were evaluated. The molecular structure of H2Pc thin films is confirmed by analysis of (FTIR) spectra. The surface morphology of H2Pc thin films was examined by scanning electron microscope. The absorption spectra of H2Pc recorded in the UV – VIS – IR region for the as-deposited and the annealed thin films of different thickness have been analyzed. The spectra showed two absorption bands namely the Q-band and the Soret (B)-band. The Q-band shows its characteristic splitting (Davydove splitting) with ∆Q = 0.21 eV. Values of some important optical parameters, namely optical absorption coefficient (α ′ ), molar extinction coefficient (εmolar), half-band-width (∆λ), electronic dipole strength (q 2 ) and oscillator strength (f) were calculated. The fundamental and the onset of the indirect energy gaps were also determined as 2.47 and 1.4 eV, respectively.Proučavali smo strukturna svojstva i apsorpcijske spektre tankih slojeva H2Pc. Te tanke slojeve, debljine 60 do 460 nm, naparavali smo na staklene i kremene ploče. Proučavanje rendgenograma je pokazalo da su neobrađeni tanki slojevi monokliničke α-strukture. Odredili smo srednju veličinu kristalita (L), gustoću dislokacija (δ) i naprezanje (ξ). Potvrdili smo molekulsku strukturu tankih slojeva H2Pc analizama FTIR spektara. Površine slojeva ispitivali smo pretražnim elektronskim mikroskopom. Analizirali smo apsorpcijske spektre neobrađenih i opuštenih tankih slojeva različite debljine u UV – VIS – IR području. Ti spektri pokazuju dvije apsorpcijske vrpce, Q-vrpcu i Soretovu B-vrpcu. Q-vrpca pokazuje svoju značajku (Davydovog) cijepanja sa ∆Q = 0.21 eV. Izveli smo vrijednosti važnih optičkih parametara: optičkog apsorpcijskog koeficijenta (α ′ ), molarnog koeficijenta gašenja (εmolar), poluširine pojasa (∆λ), elektronskih dipolnih jakosti (q 2 ) i oscilatornih jakosti (f). Odredili smo osnovne energijske procijepe i početke neizravnih energijskih procijepa od 2.47 odnosno 1.4 eV

Strukturna svojstva i UV – NIR apsorpcijski spektri bezmetalnih tankih slojeva ftalocijanina

The structural properties and absorption spectra of H2Pc thin films have been studied. The films used in these studies were thermally evaporated on glass/quartz substrates with thickness ranging from 60 to 460 nm. The XRD studies of H2Pc thin films showed that the as-deposited films have α-form with monoclinic system. The mean crystallite size (L), the dislocation density (δ) and the strain (ξ) were evaluated. The molecular structure of H2Pc thin films is confirmed by analysis of (FTIR) spectra. The surface morphology of H2Pc thin films was examined by scanning electron microscope. The absorption spectra of H2Pc recorded in the UV – VIS – IR region for the as-deposited and the annealed thin films of different thickness have been analyzed. The spectra showed two absorption bands namely the Q-band and the Soret (B)-band. The Q-band shows its characteristic splitting (Davydove splitting) with ∆Q = 0.21 eV. Values of some important optical parameters, namely optical absorption coefficient (α ′ ), molar extinction coefficient (εmolar), half-band-width (∆λ), electronic dipole strength (q 2 ) and oscillator strength (f) were calculated. The fundamental and the onset of the indirect energy gaps were also determined as 2.47 and 1.4 eV, respectively.Proučavali smo strukturna svojstva i apsorpcijske spektre tankih slojeva H2Pc. Te tanke slojeve, debljine 60 do 460 nm, naparavali smo na staklene i kremene ploče. Proučavanje rendgenograma je pokazalo da su neobrađeni tanki slojevi monokliničke α-strukture. Odredili smo srednju veličinu kristalita (L), gustoću dislokacija (δ) i naprezanje (ξ). Potvrdili smo molekulsku strukturu tankih slojeva H2Pc analizama FTIR spektara. Površine slojeva ispitivali smo pretražnim elektronskim mikroskopom. Analizirali smo apsorpcijske spektre neobrađenih i opuštenih tankih slojeva različite debljine u UV – VIS – IR području. Ti spektri pokazuju dvije apsorpcijske vrpce, Q-vrpcu i Soretovu B-vrpcu. Q-vrpca pokazuje svoju značajku (Davydovog) cijepanja sa ∆Q = 0.21 eV. Izveli smo vrijednosti važnih optičkih parametara: optičkog apsorpcijskog koeficijenta (α ′ ), molarnog koeficijenta gašenja (εmolar), poluširine pojasa (∆λ), elektronskih dipolnih jakosti (q 2 ) i oscilatornih jakosti (f). Odredili smo osnovne energijske procijepe i početke neizravnih energijskih procijepa od 2.47 odnosno 1.4 eV

Carcinome epidermoïde du larynx chez la femme

Le cancer du larynx est assez rare chez la femme. Cependant, il risque d’être en recrudescence à cause de l’augmentation du tabagisme féminin. Peu de travaux se sont consacrés à rechercher les spécificités du cancer du larynx chez la femme.But: Analyser le profil épidémiologique et clinique des femmes porteuses d’un carcinome épidermoïde du larynx et dégager les caractéristiques thérapeutiques, évolutives et les facteurs pronostiques chez cette population.Méthodes: étude rétrospective portant sur 50 femmes prises en charge pour un carcinome épidermoïde du larynx sur une période de treize ans (1994-2006).Résultats : L’âge moyen de nos patientes était de 63,5 ans. L’intoxication tabagique était retrouvée chez 32,6% des patientes. Chez 30% de nos patientes aucun facteur de risque n’a été retrouvé. Les signes cliniques étaient dominés par la dysphonie suivie de la dyspnée et la dysphagie. Les tumeurs prenaient naissanceau dépend de l’étage glottique dans 55,8% des cas. Nous avons relevé que 60,4% des tumeurs étaient vus à un stade évolué T3-T4 et que 95,3% des tumeurs étaient initialement classées N0. La chirurgie a été pratiquée chez 47,5% des patientes tandis que 16,2% ont reçu une radio-chimiothérapie. La survie globale cumulée était de 78,8% à 3 ans et de 73,5% à 5 ans.Conclusion : L’absence des facteurs de risque classiques chez un grand nombre de nos patientes laisse supposer le rôle d’autres facteurs étiopathogéniques dans la genèse du cancer du larynx chez la femme. Toute dysphonie chez la femme doit être explorée même en l’absence de facteurs de risque. La prise en charge et le pronostic semblent superposables à celui de l’homme.Mots clés : Tumeur – Larynx – Femme – Epidémiologie – TabagismeLaryngeal cancer is quite uncommun in women. However, it may be on the rise due to the increase in smoking among women. Few studies have been devoted to find the specifics of laryngeal cancer in women.Purpose: to analyze the epidemiological and clinical profile of squamous cell carcinoma of the larynx in women, and to identify therapeutic characteristics and prognostic factors in this population.Methods: retrospective study of 50 womens treated for squamous cell carcinoma of the larynx over a period of thirteen years (1994- 2006).Results: The mean age of our patients was 63.5 years. The tobacco abuse was found in 32.6% of patients. In 30% of our patients no risk factors were found. Clinical signs were dominated by dysphonia followed by dyspnea and dysphagia. Primary tumor was localized in glottis in 55.8% of cases. We found that 60.4% of tumors were seen at an advanced stage T3-T4 and 95.3% of the tumors were initially classified N0. The surgery was performed in 47.5% of patients, while 16.2% received chemoradiotherapy. The cumulative overall survival was 78.8% at 3 years and 73.5% at 5 years.Conclusion: The absence of conventional risk factors in a large number of our patients suggests the role of other etiologic factors in the genesis of laryngeal cancer in women. Every dysphonia in women should be explored even in the absence of risk factors. The  management and prognosis seem congruent with that of man.Key words: Tumor-larynx-women-epidemiology-smokin