Effect of Liquid Droplets on Turbulence Structure in a Round Gaseous Jet

A second-order model which predicts the modulation of turbulence in jets laden with uniform size solid particles or liquid droplets is discussed. The approach followed is to start from the separate momentum and continuity equations of each phase and derive two new conservation equations. The first is for the carrier fluid's kinetic energy of turbulence and the second for the dissipation rate of that energy. Closure of the set of transport equations is achieved by modeling the turbulence correlations up to a third order. The coefficients (or constants) appearing in the modeled equations are then evaluated by comparing the predictions with LDA-measurements obtained recently in a turbulent jet laden with 200 microns solid particles. This set of constants is then used to predict the same jet flow but laden with 50 microns solid particles. The agreement with the measurement in this case is very good

Temporal Discontinuity for Splitting Polarization States of Light

Recently, time-varying electromagnetic structures have been extensively investigated to unveil new physical phenomena. In this direction, one of the important and historical topics is studying temporal discontinuities in these structures. Here, we consider fast changes of bianisotropic media. Specifically, we focus on introducing a temporal interface between isotropic chiral and dielectric media. We show that due to the discontinuity in time, interestingly, a linearly polarized electromagnetic wave is decomposed into forward right-handed and forward left-handed circularly polarized waves having different angular frequencies and the same phase velocities. This salient effect allows splitting light to two different polarization states with high efficiency. Hopefully, our findings will be useful as a possibility to control polarization states of light

Inclusion properties of certain subclasses of analytic functions defined by generalized Salagean operator

Let $A$ denote the class of analytic functions with the normalization $f(0)=f^{\prime }(0)-1=0$ in the open unit disc U=\{z:\left\vert z\right\vert <1\}.  Set $$f_{\lambda }^{n}(z)=z+\sum_{k=2}^{\infty }[1+\lambda (k-1)]^{n}z^{k}\quad(n\in N_{0};\ \lambda \geq 0;\ z\in U),$$ and define $f_{\lambda ,\mu }^{n}$ in terms of the Hadamard product f_{\lambda }^{n}(z)\ast f_{\lambda ,\mu }^{n}=\frac{z}{(1-z)^{\mu }}\quad (\mu >0;\ z\in U). In this paper, we introduce several subclasses of analytic functions defined by means of the operator $I_{\lambda ,\mu }^{n}:A\longrightarrow A$, given by I_{\lambda ,\mu }^{n}f(z)=f_{\lambda ,\mu }^{n}(z)\ast f(z)\quad (f\in A;\ n\in N_{0;}\ \lambda \geq 0;\ \mu >0). Inclusion properties of these classes and the classes involving the generalized Libera integral operator are also considered

One-Year Results of Simultaneous Topography-Guided Photorefractive Keratectomy and Corneal Collagen Cross-Linking in Keratoconus Utilizing a Modern Ablation Software

Purpose. To evaluate effectiveness of simultaneous topography-guided photorefractive keratectomy and corneal collagen cross-linking in mild and moderate keratoconus. Methods. Prospective nonrandomized interventional study including 20 eyes of 14 patients with grade 1-2 keratoconus that underwent topography-guided PRK using a Custom Ablation Transition Zone (CATz) profile with 0.02% MMC application immediately followed by standard 3 mw/cm2 UVA collagen cross-linking. Maximum ablation depth did not exceed 58 μm. Follow-up period: 12 months. Results. Progressive statistically significant improvement of UCVA from 0.83±0.37 logMAR preoperative, reaching 0.25±0.26 logMAR at 12 months (P<0.001). Preoperative BCVA (0.27±0.31 logMAR) showed a progressive improvement reaching 0.08±0.12 logMAR at 12 months (P=0.02). Mean Kmax reduced from 48.9±2.8 to 45.4±3.1 D at 12 months (P<0.001), mean Kmin reduced from 45.9±2.8 D to 44.1±3.2 D at 12 months (P<0.003), mean keratometric asymmetry reduced from 3.01±2.03 D to 1.25±1.2 D at 12 months (P<0.001). The safety index was 1.39 at 12 months and efficacy index 0.97 at 12 months. Conclusion. Combined topography-guided PRK and corneal collagen cross-linking are a safe and effective option in the management of mild and moderate keratoconus. Precis. To our knowledge, this is the first published study on the use of the CATz ablation system on the Nidek Quest excimer laser platform combined with conventional cross-linking in the management of mild keratoconus

Neke značajke fizičkih svojstava praha nikal oksida

Nickel oxide powder was prepared by firing spec pure NiCO3 in air for 6 hours at different firing temperatures ranged from 800◦C to 1200◦C. The crystal structure of all samples is a cubic structural as obtained from XRD study. The diffuse reflectance of different samples of NiO was measured at room temperature in the wavelength range from 200 to 2000 nm. The energy gap of NiO samples was then deduced as well as the position and number of different transitions which were found to be dependent on the firing temperature. The electrical conductivity σm was measured over temperature range from 50◦C to 320◦C and frequency range from 42 Hz to 5 MHz. The conductivity decreases with increasing firing temperature and increases with frequency. The activation energy was calculated and was found to increase with increasing firing temperature. Electron spin resonance (ESR) spectra were recorded at room temperature as first derivatives using an X-band spectrometer with a magnetic field modulation of 100 kHz. The intensity of the ESR-spectra of NiO samples decreases with increasing firing temperature.Prah nikal oksida smo pripremali 6-satnim prženjem NiCO3 u zraku na nizu temperatura između 800◦C i 1200◦C. Kristalna struktura svih uzoraka je kubna kako smo utvrdili rentgenskom difrakcijom. Difuznu reflektivnost uzoraka NiO mjerili smo na sobnoj temperaturi u području valnih duljina 200 do 2000 nm. Utvrdili smo energijski procjep kao i položaj i broj niza prijelaza i ustanovili da ovise o temperaturi prženja. Mjerili smo električnu vodljivost σm na temperaturama 50◦C do 320◦C i u području frekvencija 42 Hz do 5 MHz. Vodljivost se smanjuje za veće temperature prženja a raste s frekvencijom. Izračunali smo aktivacijsku energiju i našli da raste s povećanjem temperature prženja. Mjerili smo spektre elektronske spinske rezonancije (ESR) na sobnoj temperaturi kao prve derivacije pomoću spektrometra u pojasu X, modulirajući magnetsko polje sa 100 kHz. Intenzitet spektara ESR uzoraka NiO smanjuje se s povećanjem temperature prženja

Neke značajke fizičkih svojstava praha nikal oksida

Nickel oxide powder was prepared by firing spec pure NiCO3 in air for 6 hours at different firing temperatures ranged from 800◦C to 1200◦C. The crystal structure of all samples is a cubic structural as obtained from XRD study. The diffuse reflectance of different samples of NiO was measured at room temperature in the wavelength range from 200 to 2000 nm. The energy gap of NiO samples was then deduced as well as the position and number of different transitions which were found to be dependent on the firing temperature. The electrical conductivity σm was measured over temperature range from 50◦C to 320◦C and frequency range from 42 Hz to 5 MHz. The conductivity decreases with increasing firing temperature and increases with frequency. The activation energy was calculated and was found to increase with increasing firing temperature. Electron spin resonance (ESR) spectra were recorded at room temperature as first derivatives using an X-band spectrometer with a magnetic field modulation of 100 kHz. The intensity of the ESR-spectra of NiO samples decreases with increasing firing temperature.Prah nikal oksida smo pripremali 6-satnim prženjem NiCO3 u zraku na nizu temperatura između 800◦C i 1200◦C. Kristalna struktura svih uzoraka je kubna kako smo utvrdili rentgenskom difrakcijom. Difuznu reflektivnost uzoraka NiO mjerili smo na sobnoj temperaturi u području valnih duljina 200 do 2000 nm. Utvrdili smo energijski procjep kao i položaj i broj niza prijelaza i ustanovili da ovise o temperaturi prženja. Mjerili smo električnu vodljivost σm na temperaturama 50◦C do 320◦C i u području frekvencija 42 Hz do 5 MHz. Vodljivost se smanjuje za veće temperature prženja a raste s frekvencijom. Izračunali smo aktivacijsku energiju i našli da raste s povećanjem temperature prženja. Mjerili smo spektre elektronske spinske rezonancije (ESR) na sobnoj temperaturi kao prve derivacije pomoću spektrometra u pojasu X, modulirajući magnetsko polje sa 100 kHz. Intenzitet spektara ESR uzoraka NiO smanjuje se s povećanjem temperature prženja

Improvement of Synchronous Machine Dynamic Characteristics via Neural Network Based Controllers

This paper presents Simulation and experimental study aimed at investigating the effectiveness of an adaptive artificial neural network stabilizer on enhancing the damping torque of a synchronous generator. For this purpose, a power system comprising a synchronous generator feeding a large power system through a short tie line is considered. The proposed adaptive neuro-control system consists of two multi-layered feed forward neural networks, which work as a plant model identifier and a controller. It generates supplementary control signals to be utilized by conventional controllers. The details of the interfacing circuits, sensors and transducers, which have been designed and built for use in tests, are presented. The synchronous generator is tested to investigate the effect of tuning a Power System Stabilizer (PSS) on its dynamic stability. The obtained simulation and experimental results verify the basic theoretical concepts

Influence of spraying with gibberellic acid on behavior of Anna Apple trees

Abstract: This investigation wasconducted during two successiveseasons 2003/2004 and 2004/2005 on seven years old Anna apple trees budded on (MM. 106) rootstock and irrigated via drip system. Trees were sprayed with 250 ppm of gibberellic acid (GA 3 ) once at early May (6 weeks after full bloom) or twice at the previous date and at late July (l6 weeks after full bloom). The results indicated that gibberellic acid (GA 3 ) treatments significantlyincreased the vegetative growth parameters i.e., number of newgrowing shoot tips, shoot diameter, number of leaves developed on current shoots, total area of leaves developed on new current shoots per tree and leaf dry weight compared with the untreated trees. Although, the earlier application of GA 3 delayed bud break, gibberellic acid treatment at both times of application increased the percentage of lateral bud break of the next spring compared with the control trees. Gibberellic acid treatments had no effect on the flowering density atthe next spring of the applications. However, the percentages of both fruiting spursand fruiting lateral developed on one year old shoots of the next spring after the treatments were reduced. In general, the percentages of both initial and final fruit set at the next spring of GA 3 applications were significantly reduced for both spur bud inflorescences and mixed floral lateral buds developed on one year old shoots. Carbohydrates reserves of woody spurs were reduced for earlier application of GA 3