Predictive control of wind turbines by considering wind speed forecasting techniques

A wind turbine system is operated such that the points of wind rotor curve and electrical generator curve coincide. In order to obtain maximum power output of a wind turbine generator system, it is necessary to drive the wind turbine at an optimal rotor speed for a particular wind speed. A Maximum Power Point Tracking (MPPT) controller is used for this purpose. In fixed-pitch variable-speed wind turbines, wind-rotor parameters are fixed and the restoring torque of the generator needs to be adjusted to maintain optimum rotor speed at a particular wind speed for optimum power output. In turbulent wind environment, control of variable-speed fixed-pitch wind turbine systems to continuously operate at the maximum power points becomes difficult due to fluctuation of wind speeds. In this paper, wind speed forecasting techniques will be considered for predictive optimum control system of wind turbines

Pressure induced electronic topological transition in Sb2S3

Pressure induced electronic topological transitions in the wide band gap semiconductor Sb2S3 (Eg = 1.7-1.8 eV) with similar crystal symmetry (SG: Pnma) to its illustrious analog, Sb2Se3, has been studied using Raman spectroscopy, resistivity and the available literature on the x-ray diffraction studies. In this report, the vibrational and the transport properties of Sb2S3 have been studied up to 22 GPa and 11 GPa, respectively. We observed the softening of phonon modes Ag(2), Ag(3) and B2g and a sharp anomaly in their line widths at 4 GPa. The resistivity studies also shows an anomaly around this pressure. The changes in resistivity as well as Raman line widths can be ascribed to the changes in the topology of the Fermi surface which induces the electron-phonon and the strong phonon-phonon coupling, indicating a clear evidence of the electronic topological transition (ETT) in Sb2S3. The pressure dependence of a/c ratio plot obtained from the literature showed a minimum at ~ 5 GPa, which is consistent with our high pressure Raman and resistivity results. Finally, we give the plausible reasons for the non-existence of a non-trivial topological state in Sb2S3 at high pressures.Comment: 24 pages, 6 Figures, 2 tables submitted for publicatio

Transformations of q-boson and q-fermion algebras

We investigate the algebras satisfied by q-deformed boson and fermion oscillators, in particular the transformations of the algebra from one form to another. Based on a specific algebra proposed in recent literature, we show that the algebra of deformed fermions can be transformed to that of undeformed standard fermions. Furthermore we also show that the algebra of q-deformed fermions can be transformed to that of undeformed standard bosons.Comment: 7 pages, RevTe

Comparison of plain egg medium with Lowenstein- Jensen medium in the isolation of M. tuberculosis from sputum

The isolation of tubercle bacilli from sputum using a plain egg (PE) medium and the conventional Lowenstein-Jensen (L-J) medium has been investigated on 703 specimens. The isolation of positive cultures and the grades of positivity were similar with the two media. There was an indication that the growth on the PE medium was faster than on L-J medium. The incidence of contamination was similar and low (4.0 per cent on PE and 3.8 per cent on L-J medium). Being cheaper and simpler than L-J medium, the PE medium is ideally suited for the routine culturing of tubercle bacilli

Simple qualitative tests for rifampicin in urine

Simple qualitative tests for rifampicin in urine, involving extraction with chloroform as well as with benzene were investigated on 50 patients. A positive test result was obtained in 98-100% of the specimens between 3 and 11 hours after drug administration by both methods. All specimens collected prior to administration of rifampicin as also specimens collected after ingestion of other anti-tuberculosis drugs were negative by both methods. However, the chloroform extraction method yielded positive reactions in 26% of 27 specimens collected after the administration of c l o f a z i m i n e

No Eigenvalue in Finite Quantum Electrodynamics

We re-examine Quantum Electrodynamics (QED) with massless electron as a finite quantum field theory as advocated by Gell-Mann-Low, Baker-Johnson, Adler, Jackiw and others. We analyze the Dyson-Schwinger equation satisfied by the massless electron in finite QED and conclude that the theory admits no nontrivial eigenvalue for the fine structure constant.Comment: 13 pages, Late

3D MPRAGE improves classification of cortical lesions in multiple sclerosis.

BACKGROUND: Gray matter lesions are known to be common in multiple sclerosis (MS) and are suspected to play an important role in disease progression and clinical disability. A combination of magnetic resonance imaging (MRI) techniques, double-inversion recovery (DIR), and phase-sensitive inversion recovery (PSIR), has been used for detection and classification of cortical lesions. This study shows that high-resolution three-dimensional (3D) magnetization-prepared rapid acquisition with gradient echo (MPRAGE) improves the classification of cortical lesions by allowing more accurate anatomic localization of lesion morphology. METHODS: 11 patients with MS with previously identified cortical lesions were scanned using DIR, PSIR, and 3D MPRAGE. Lesions were identified on DIR and PSIR and classified as purely intracortical or mixed. MPRAGE images were then examined, and lesions were re-classified based on the new information. RESULTS: The high signal-to-noise ratio, fine anatomic detail, and clear gray-white matter tissue contrast seen in the MPRAGE images provided superior delineation of lesion borders and surrounding gray-white matter junction, improving classification accuracy. 119 lesions were identified as either intracortical or mixed on DIR/PSIR. In 89 cases, MPRAGE confirmed the classification by DIR/PSIR. In 30 cases, MPRAGE overturned the original classification. CONCLUSION: Improved classification of cortical lesions was realized by inclusion of high-spatial resolution 3D MPRAGE. This sequence provides unique detail on lesion morphology that is necessary for accurate classification

Generalized symmetric nonextensive thermostatistics and q-modified structures

We formulate a convenient generalization of the q-expectation value, based on the analogy of the symmetric quantum groups and q-calculus, and show that the q->q^{-1} symmetric nonextensive entropy preserves all of the mathematical structure of thermodynamics just as in the case of non-symmetric Tsallis statistics. Basic properties and analogies with quantum groups are discussed.Comment: 9 pages, 1 figure. To appear in Mod. Phys. Lett.

Optical power limiting in the femtosecond regime by silver nanoparticle–embedded polymer film

A simple methodology is developed for the fabrication of freestanding polymer films with embedded silver nanoparticles grown in situ. Strong nonlinear absorption, positive nonlinear refraction, and efficient optical limiting in the femtosecond regime are demonstrated with these films. Additional investigations with supported films as well as parallel studies in the nanosecond regime are also presented. The freestanding nature of the films is not only of potential interest from the application perspective but also facilitates the unambiguous determination of the nonlinear coefficients of the metal nanoparticles embedded in polymer matrix without complications arising due to the contributions from the substrate

Determination of Acetylator Phenotype Based on the Ratio of Acetylisoniazid to Isoniazid in Urine Following an Oral Dose of Ordinary Isoniazid

A simple method for classifying subjects as slow or rapid inactivators of isoniazid has been described. A uniform dose of 300 mg. of ordinary isoniazid was administered orally to 150 patients with pulmonary tuberculosis. The ratio of acetylisoniazid to isoniazid was determined in urine collected at hourly intervals from 4 to 8 h. At each hour the distribution of the ratios was clearly bimodal. The test based on the 5-6 h. urine collection is recommended for its convenience and excellent discrimination between slow and rapid inactivators. The agreement between this method and a ‘standard method was of the order of 97 per cent