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Thin films of Nb2O5 were synthesized by RF sputtering. The effect of annealing, at different temperatures (100, 150, 200, 250, 300, 350, and 400 °C), on the structural and optical properties was studied. The crystallinity and structural characteristics of the Nb2O5 thin films were examined employing the X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD and SEM analyses showed an amorphous nature for the as-deposited and annealed samples from 100 to 350 °C and crystalline structure for the annealed sample at 400 °C. The high values of the transmittance and low reflection make these films used as a window layer in solar cell systems. Upon increasing annealing temperature, the energy band gap Eg increased from 4.039 to 4.175 eV. Eg high values again make these films suitable to be used as a window layer in solar cell system. Urbach tail, EU, decreased with increasing annealing temperature. The refractive index showed the normal dispersion. The dispersion energies were found to have the same behavior with respect to annealing temperature, besides, the single oscillator energy Eₒ had a lower value compared to the dispersion energy Ed. The plasma frequency ω p was found to increase with annealing temperature. The first and third optical moments had peak values depending on the incident photon energy. [ABSTRACT FROM AUTHOR]

MnSmO3 thin films were deposited by radio frequency magnetron sputtering method with pure argon flow rate (20, 30, 45, 50, and 60 sccm). The crystalline and morphological structures of MnSmO3 thin films were examined using X-ray diffraction and scanning electron microscopy revealing amorphous nature. Optical properties MnSmO3 thin films showed direct transition and normal dispersion of the refractive index at all rate of flow. The optical energy gap decreased with increasing the rate of flow, whereas the plasma behaved contrary to that of the optical gap. The dispersion energies deduced from Drude models are found to be larger than that of the single-oscillator energies. Non-linear refractive index is found to decrease with increasing the rate of flow. The linear and non-linear optical susceptibilities showed a tendency of decreasing with increasing the rate of flow. [ABSTRACT FROM AUTHOR]

The operation and effectiveness of a solar-powered underground water pumping system are affected by many environmental and technical factors. The impact of these factors must be investigated to be considered when developing these systems and to ensure their dependability. This study evaluated the dependability and performance of photovoltaic water pumping system (PVWPS) under real operating conditions by examining the effects of solar irradiance, panels' temperature, and components' efficiency. From December 2020 to June 2021, experiments were conducted on a 10 hp PVWPS located in Bani Salamah, Al-Qanater-Giza Governorate, Egypt, at latitude 30.3° N, longitude 30.8° E, and 19 m above sea level. The irradiance values reached 755.7, 792.7, and 805.7 W/m2 at 12:00 p.m. in December, March, and June, respectively. Furthermore, the irradiance has a significant impact on the pump flow rate, as the amount of pumped water during the day reached 129, 164.1, and 181.8 m3/day, respectively. The panels' temperatures rose to 35.7 °C, 39.9 °C, and 44 °C, respectively. It was observed that when the temperature rises by 1 degree Celsius, efficiency falls by 0.48%. The average efficiency of photovoltaic solar panels reached its highest value in March (13.8%) and its lowest value in December (13%). [ABSTRACT FROM AUTHOR]

The complex crystal and magnetic structure of strontium-doped ytterbium manganites using high-resolution neutron diffraction at low temperature starting from 2.6 K has been studied. Yb0.6Sr0.4MnO3 was crystallized with the mixed phases of crystal structure: orthorhombic with Pbnm space group enclosing Jahn–Teller Mn3+ ions, and hexagonal crystal system of P63cm space group describing JT ions free phase over the whole temperature range. From the refinement of the neutron diffraction patterns, a distinguished difference in the behaviors of the two phases was observed with a variation in temperature where opposite lattice—temperature-dependent behavior was found. The magnetic ordering in hexagonal symmetry was frustrated and was having a canted spin of Mn magnetic moments in the plane of the Г2-type symmetry. Mn ions were arranged together in the well-separated triangular layers parallel to (ab) plane as a result of the antiferromagnetic exchange interaction between the spins of atoms in the most nearest neighbors, which make the Mn spin subsystem of low-dimensional and frustrated at TN≈150 K. The other phase of the orthorhombic crystal system showed the C-type antiferromagnetic at TN≈70 K. The contribution of Yb atom in the magnetic ordering down to T = 2.6 K has not been registered. The magnetization–temperature dependence of Yb0.6Sr0.4MnO3 at different applied magnetic field was calculated using Monte Carlo simulation based on Ising model. Theoretically calculated model and experimental data were in good agreement. The complex magnetic ordering of the Yb0.6Sr0.4MnO3 for the mixed crystal structure was well described by Ising model. [ABSTRACT FROM AUTHOR]

In this report, we investigate the optical and electrical properties of aluminum zinc oxide (AZO) thin films using magnetron sputtering method in preparing the thin films and spectrophotometer to measure the optical characteristics. The X-ray diffraction (XRD) patterns of the films are found to have amorphous structure. The optical band gap Eg, refractive index n, electronic α Ep polarizability, carrier concentration Nc, plasma frequency ω p , electrical resistivity ρ s , and sheet resistance R sh are found to decrease with increasing the RF power of Al2O3 target. The refractive index shows a normal dispersion. Urbach energy Eu and figure of merit are found to increase with increasing the RF power of Al2O3 target. Our results manifest that the change of the RF power of the Al2O3 target can improve the AZO thin films, which is appropriate for solar sell applications. [ABSTRACT FROM AUTHOR]

Thin films of CdTe/CdS were prepared using the thermal evaporation technique with pressure 2 × 10−5 mbar on substrate from glass. The thickness of CdCl2 layer around 150 nm was deposited making as-deposited CdTe/CdS films. The films covered by cadmium chloride (CdCl2) layer were annealed in atmosphere of (O2 + Ar) at different temperatures of 400 °C, 450 °C and 480 °C for 15 min. The effect of CdCl2 as a top layer on morphological, structural and optical properties was studied, and the results were compared with as-deposited films and also with (O2 + Ar) annealing process. The refractive index in whole wavelength and film thickness was estimated by Cauchy dispersion relation and Swanepoel's envelope method, respectively. Furthermore, many optical parameters such as transmittance, absorbance, reflectance, and optical band gap, Urbach energy, film thickness, electronic polarizability, lattice dielectric constant were calculated also in this study. The heat treatment of our films with depositing CdCl2 layer in (O2 + Ar) flow lowered the energy gap which led CdTe/CdS films to be a candidate to work in thin-film solar cells as an absorber layer. [ABSTRACT FROM AUTHOR]

Abstract Purpose To evaluate the role of diffusion weighted MRI (DW MRI) in the differentiating between benign and malignant pancreatic masses. Patients and Methods Sixty patients (36 men, mean age, 62 years; range, 48–72 years], 24 women (mean age, 64 years; range, 54–69 years] suspected to have solid pancreatic masses were examined by conventional and DWI. None of our patients had a history of pancreatic disease. DWI of the pancreas was performed in addition to the routine liver MR. Final diagnosis was obtained by diagnostic biopsy, lab. data and follow up. Results 38 patients had a benign lesion and 22 patients had a malignant lesion. Using DWI, 36 cases were diagnosed to have benign lesions and 24 cases were diagnosed to have malignant lesions. There were two false positive cases due to low ADC value. The mean ADC values of malignant lesions were lower compared with benign lesion. The mean ADC value for malignant lesions was 1.1 +/− 0.201 × 10−3 mm2/sec, and for benign lesions it was 1.6 + l − 0.121 × 10−3 mm2/sec. Conclusion DWI and ADC values can help differentiate between benign and malignant pancreatic masses. Also DWI can be used for investigating patients for whom contrast-enhanced CT or MRI studies are contraindicated. [ABSTRACT FROM AUTHOR]

This paper presents a new single-phase asymmetrical cascaded multilevel DC-link inverter. The proposed inverter comprises two stages. The main stage of the inverter consists of multiple similar cells, each of which is a half-bridge inverter consisting of two switches and a single DC source. All cells are connected in a cascaded manner with a fixed neutral point. The DC source values are not made equal to increase the performance of the inverter. The second circuit is a folded cascaded H-bridge circuit operating at a line frequency. One of the main advantages of this proposed topology is that it is a modular type and can thus be extended to high stages without changing the configuration of the main stage circuit. Two control schemes, namely, low switching with selective harmonic elimination and sinusoidal pulse width modulation, are employed to validate the proposed topology. The detailed approach of each control scheme and switching pulses are discussed in detail. A 150W prototype of the proposed system is implemented in the laboratory to verify the validity of the proposed topology. [ABSTRACT FROM AUTHOR]

This paper presents a single-phase five-level inverter controlled by two novel pulse width modulation (PWM) switching techniques. The proposed PWM techniques are designed based on minimum switching power loss and minimum total harmonic distortion (THD). In a single-phase five-level inverter employing six switches, the first proposed PWM technique requires four switches to operate at switching frequency and two other switches to operate at line frequency. The second proposed PWM technique requires only two switches to operate at switching frequency and the rest of the switches to operate at line frequency. Compared with conventional PWM techniques for single-phase five-level inverters, the proposed PWM techniques offer high efficiency and low harmonic components in the output voltage. The validity of the proposed PWM switching techniques in controlling single-phase five-level inverters to regulate load voltage is verified experimentally using a 100 V, 500 W laboratory prototype controlled by dspace 1103. [ABSTRACT FROM AUTHOR]

The paper presents an accurate loss model based controller of an induction motor to calculate the optimal air gap flux. The model includes copper losses, iron losses, harmonic losses, friction and windage losses, and stray losses. These losses are represented as a function of the air gap flux. By using the calculated optimal air gap flux compared with rated flux for speed sensorless indirect vector controlled induction motor, an improvement in motor efficiency is achieved. The motor speed performance is improved using a fuzzy logic speed controller instead of a PI controller. The fuzzy logic speed controller was simulated using the fuzzy control interface block of MATLAB/SIMULINK program. The control algorithm is experimentally tested within a PC under RTAI-Linux. The simulation and experimental results show the improvement in motor efficiency and speed performance. [ABSTRACT FROM AUTHOR]

The original version of this article unfortunately contained a mistake. [ABSTRACT FROM AUTHOR]