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Purpose. In recent years, the photovoltaic systems (PV) become popular due to several advantages among the renewable energy. Tracking maximum power point in PV systems is an important task and represents a challenging issue to increase their efficiency. Many different maximum power point tracking (MPPT) control methods have been proposed to adjust the peak power output and improve the generating efficiency of the PV system connected to the grid. Methods. This paper presents a Beta technique based MPPT controller to effectively track maximum power under all weather conditions. The effectiveness of this algorithm based MPPT is supplemented by a comparative study with incremental conductance (INC), particle swarm optimization (PSO), and fuzzy logic control (FLC). Results Faster MPPT, lower computational burden, and higher efficiency are the key contributions of the Beta based MPPT technique than the other three techniques., Мета. В останні роки фотоелектричні системи набули популярності завдяки низці переваг серед відновлюваних джерел енергії. Відстеження точки максимальної потужності у фотоелектричних системах є важливим завданням і складною проблемою для підвищення їх ефективності. Було запропоновано безліч різних методів керування відстеженням точки максимальної потужності (ВТМП) для регулювання пікової вихідної потужності та підвищення ефективності генерації фотоелектричної системи, підключеної до мережі. Методи. У цій статті представлений контролер ВТМП, заснований на бета-методі, для ефективного відстеження максимальної потужності за будь-яких погодних умов. Ефективність ВТМП на основі цього алгоритму доповнюється порівняльним дослідженням з інкрементною провідністю, оптимізацією рою частинок та нечітким логічним управлінням. Результати. Швидше ВТМП, менші витрати на обчислення та більша ефективність є ключовими перевагами методу ВТМП на основі бета-методу порівняно з трьома іншими методами.

This study examined a production system under deterioration and its impact on the degradation of the environment. The environment degrades as the production system reaches a certain level of deterioration. To reduce environmental degradation, the system's deterioration is monitored through scheduled inspections, after which preventive or corrective actions are taken. To achieve the optimum inspection dates that minimize the average total cost per time unit, the Fminsearch algorithm was applied to calculate the optimal inspection dates for two cases of sequential inspection: periodic and aperiodic. To validate the performance of the proposed Fminsearch algorithm, simulation results were compared with the Nelder-Mead method. The comparison results showed the superiority of the Fminsearch algorithm in optimizing inspection maintenance dates to reduce the environmental degradation ratio.

Maximum Power Point Tracking (MPPT) is essential for the application of a photovoltaic (PV) energy system in order to extract the maximum possible power under variable conditions of irradiation and temperature. This paper deals with the implementation of different MPPT algorithms for a PV array installed for a system connected to the Grid: Perturb and Observe (P&O), Fuzzy Logic Control (FLC), Cuckoo Search (CS), and Beta algorithms were simulated in Matlab/Simulink and the results were analyzed and compared. Beta algorithm proved to have greater tracking power, minor power loss, great tracking speed, less time, and less oscillation than the other techniques.

We report computational results on the optical response of quarter-wave periodic, modified periodic and optimized photonic crystals based on Ge and MgF2 materials. Transfer matrix method and pattern-search optimization algorithm have been combined to achieve high performance structures destined to spectral control in thermophotovoltaic systems. Our computations demonstrate that the pattern-search algorithm is readily applicable to optimal design of photonic crystals within reduced computing time. High optical performance and spectral efficiency have been achieved.

Mixed thin films of (SnS 2 ) x (CdS) 1−x (0 ≤ x ≤ 1) were deposited by spray pyrolysis technique decomposition of aqueous solutions of Cadmium chloride (CdCl 2 ) and Tin chloride (SnCl 2 ) on glass substrates at a substrate temperature of 350 °C. Structural properties of the obtained films were studied by X-ray diffraction analysis. The surface morphology and elemental analysis of the films has been examined using scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDX). Optical properties of the deposited films were obtained using transmittance measurements in the wavelength range [200–2500 nm].Some optical parameters such as, high frequency dielectric constant e ∞, lattice high frequency dielectric constant e L and the dispersion parameters (oscillation energy E 0 and the dispersion energy E d ) were estimated by analyzing the refractive index data. The direct optical band gap value of these films varies from 2 to 2.41 eV. We have observed that (SnS 2 ) x (CdS) 1-x thin films conductivity obeys the Meyer–Neldel rule (E MN = 32 meV), which is interpreted as disorder parameter. The room temperature electrical resistivity of CdS (x = 0) films was found to be 2.22 10 +4 Ω cm and it decreases when content of Sn in mixed films increases and reaches the optimum value of resistivity 2.32 10 −2 Ω cm for the concentration x = 0.5. The carrier concentration was found to vary from −1.26 10 +12 to −4.50 10 +20 cm −3 and corresponding hall mobility varied from 6.51 10 +1 to 2.64 10 +1 cm 2 /VS.

The optical absorbance of four ternary thin films, i.e. MgSiP2, MgGeP2, MgSiAs2, MgGeAs2 have been theoretically examined over a wide range of wavelength from 300 nm to 800 nm. The combination of first-principle electronic structure calculations and the optical matrix approach for modeling the multilayer assembly have been employed for theoretical studies. The analysis of the calculated absorbance spectra at room temperature with unpolarized light and normal incidence, revealed that MgGeAs2 with a direct energy band gap of 1.6 eV exhibit a considerable high optical absorption, where a thickness of 3.2 μm of this thin film is sufficient to absorb 90% of the incident light and generates a maximum photocurrent of ∼23 mA/cm2.

This paper proposes frequency speed control of rotary travelling wave ultrasonic motor (TWUSM), type Daimler Benz AWM90-X motor. The control characteristics of TWUSM are complicated, highly nonlinear and varying in time. This can lead to deterioration of the performance of conventional controller such as proportional integral (PI). In order to achieve high control performance of the TWUSM, fuzzy logic controller (FLC) has been designed and compared to the conventional PI controller. To validate the performance of the proposed FLC, simulation of the speed response has been performed and analyzed for a varying load. The simulation results show that the FLC has smaller settling time, smaller rising time and minimum error in steady state. Furthermore, the fuzzy controller provides good results for large load variations. The frequency output of the controller has been validated with experimental measurements of AWM90-X.

We theoretically investigate the possibility of enhancing light absorption in graphene-based one dimensional photonic crystal. We demonstrate that it is possible to achieve total light absorption at technologically important wavelengths using one-dimensional graphene-based photonic crystals. By means of the transfer matrix method, we investigate the effect of refractive indices and layer numbers on the optical response of the structure. We found that it is possible to achieve one peak, multi-peak or broadband, and complete optical absorption. As a result, the proposed photonic structures enable myriad potential applications such as photodetection, shielding and optical sensing.

A first principles study of structural, electronic and optical properties of zinc aluminum oxide (ZnAl 2 O 4 ) by means of the full potential linear augmented plane wave method is presented. The local density approximation is used for the exchange-correlation potential. A direct band gap of 4.19 eV, in agreement with experiment ( E g =3.9 eV), was determined. ZnAl 2 O 4 is transparent in the visible spectral region; the excitonic transition associated with the fundamental band gap is 4.17 eV. The refractive index value is 1.74 in the ultraviolet spectral region.

Refractive indices and birefringences for some representative uni-axial crystals such as II- SiP 2 and II- GeP 2 have been determined over a wide range of wavelengths by the use of first-principles electronic structure calculations. First, the calculated refractive indices are fitted usually by a generalized Sellmeier equation which consists of several oscillation terms involve in its parameters more direct information about material such as electronic transitions or resonance wavelengths. Then, in contrast to all other semiconductors under discussion our spectra show a negative birefringence for CdSiP 2 in agreement with the experimental data, and they exhibit a considerable dispersion near the band gap.

In this paper we focus on the novel solar material, namely cubic TiO2. The full potential linearized augmented plane wave method in combination with the local density approximation (LDA) and the generalized gradient approximation (GGA) have been used. We calculated structural parameters, elastic constants, wave velocities and thermal properties of the material assuming the fluorite structure. The obtained values were in good agreement with the available theoretical and experimental data. Moreover, the pressure and temperature dependences of the bulk modulus, Debye temperature, Heat capacity and linear expansion coefficient have been addressed for the first time.

A new method for predicting optical characteristics of multilayer coatings based on calculated material properties is presented. This method combines the use of the full potential linear-augmented plane wave method (FP-LAPW) within the framework of the Density Functional Theory (DFT) and the optical matrix approach for modeling the multilayer assembly. The simulation process is applied to thin films of the II–VI semiconductors compounds. The optical constants of each thin film are determined by using the first principle calculations. Each layer is represented by the square Abeles matrix, including all necessary data in the calculation of the optical characteristics (as transmittance, reflectance and absorbance). The simulation of multilayer optical response includes the effect of thickness, light polarization and incident angle. The obtained results are helpful in the design of the multilayer systems with required properties.

Some works take into account the shearing deformation of frictional material, but its effect on the transient response has not yet been considered. In this paper, optimal deformation angle and resonance frequency of frictional material are investigated. Force expressions in the stator/rotor interface are developed. Mechanical characteristics taking into account the effect of shearing deformation are deduced and presented. It is shown that the shearing deformation affects the initial state as well as on the steady state. Also, the fast time response of the motor is deduced. Results of the simulation are validated using the measurements made by other researchers on traveling wave piezoelectric motor AWM90-X, Daimler-Benz type, and a prototype USM(AWM-90).

First-principles study of the ground-state properties and the stability of Ca1−xZnxO solid solutions is presented using the full-potential linearized augmented plane wave (FP-LAPW) method. We employed the local density approximation (LDA) to the exchange-correlation potential. It is found that the structural parameters, i.e., lattice constants and bulk moduli deviate from the linear function of the composition x. We determined the equation of state of the alloys and showed an increasing compressibility function of composition. The formation energy is viewed as an energetic balance between pure structural constraints and quantum chemical effects. Thus, a phase separation over the whole range of concentration is expected. The origin of the miscibility gap has a chemical nature. Also, the thermodynamic stability of the alloys was investigated.

First-principles study of the ground-state properties and the stability of Cd1−xZnxO solid solutions are presented using the full-potential linearized, augmented plane-wave (FP-LAPW) method in combination with the local density approximation (LDA). It is found that the structural parameters, i.e. lattice constants and bulk moduli strongly deviate from the linear function of the composition x . The equation of state of the alloys is determined and an increasing compressibility function of composition is found. The formation energy is viewed as an energetic balance between pure structural constraints and quantum chemical effects. Our calculations yield the prediction of phase separation over the whole range of concentration. This trend was explained to have a structural nature caused by the high lattice mismatch. Also, the thermodynamic stability of the alloys has been investigated.

Thin films of Bi2S3 were prepared by spray pyrolysis method. Optical constants, electrical and photoelectrical studies have been carried out on these films. The optical constants confirm that the Bi2S3 thin film has a direct band gap of 1.69 eV. The Hall Effect measurements indicate that the Bi2S3 thin films prepared by spray pyrolysis method are n-type in nature with a carrier concentration of 3.51 × 1017 cm− 3. An activated process with activation energy of 65 meV governs the conduction in these films. The photoconductivity measurement indicates the presence of continuously distributed localized gap states in this material.

Polycrystalline films of Bi2S3 compound have been prepared, at substrate temperature of 570 K, from Bismuth chloride (BiCl3) and Thiourea (CS (NH2)2) solutions. The structural characterisation has been carried out by the X-ray diffraction analysis (XRD). Study of optical properties shows that Bi2S3 compound has an allowed indirect transition at 1.43 eV energy. The photoelectrical parameters (diffusion length and lifetime) have been determined from the study of the photoconductivity.

Thin layers of bismuth trisulfide (Bi2S3) have been prepared for the first time by the spray pyrolysis method on glass substrates from bismuth chloride (BiCl3) and thiourea (CS(NH2)2) solutions with a concentration of 0.2 M. Films deposited on substrate at 570 K have a polycrystalline structure with crystallites size in the order of 120 A. X-Ray characterization by grazing angles diffraction (GAD) at 0.4 and 2° shows crystalline structures in surface and volume. Diffraction spectra of these films are indexed in the orthorhombic system. Studies of optical absorption in the energy range 1.5–4 eV indicate an optical gap of 1.66 eV. The Hall effect measurements indicate a carrier concentration of n=3.45×1017 cm−3.

Thin films of ZnO and CdO are prepared by the simple, economical and versatile method of chemical spray pyrolysis. This method is based on the preparation of solutions of some salt of the material whose thin films is to be prepared. The thin films obtained by this method are suitable for many scientific studies and technological applications. For the ZnO and CdO thin films, the optical properties are investigated, the energy gaps are estimated, the absorption coefficient, index refraction, extinction coefficient and real and imaginary dielectric constants as well as the lattice parameters were studied and calculated.

Polycrystalline films of Sn 2 S 3 compound were prepared on glass substrates by the spray pyrolysis technique at a substrate temperature of 270 ∘ C using tin chloride (SnCl 2 ) and thiourea (Cs(NH 2 ) 2 ) solutions with a concentration of 0.1 M. The X-ray diffraction pattern reveals an orthorhombic structure and an average grain size equal to 130 A. The optical properties of the films were studied using optical transmittance and reflectance measurements over the wavelength range 200–2500 nm. The variation of refractive index n and extinction coefficient k with photon energy are reported. The dispersion of the refractive index in Sn 2 S 3 is analysed using the concept of a single oscillator. The values of oscillator energy E 0 and dispersion energy E d are determined to be 3.98 eV and 13.5 eV, respectively. The optical constants confirm that the Sn 2 S 3 thin films have a direct band gap of 2 eV. A value of 4.35×10 −3 (Ω cm) −1 for the room temperature conductivity is found using the four-probe method.

We propose the use of a pattern search optimization technique in combination with a seed preprocessing procedure to determine the optical constants and thickness of thin films using only the transmittance spectra. The approach is quite flexible, straightforward to implement, and efficient in reaching the best fitting. We demonstrate the effectiveness of the method in extracting optical constants, even when the films are not displaying interference fringes. Comparison to a real-coded genetic algorithm shows that the modified pattern search is fast, almost accurate, and does not need any parameter adjustments. The approach is successfully applied to extract the thickness and optical constants of spray pyrolyzed nanocrystalline CdO thin films.

The development of optically transparent, electrically conductive oxides (TCOs) is relevant to a broad range of optoelectronic applications. The design of new TCOs and the optimization of existing ones require powerful modeling tools and algorithms that would be able to handle the multi-objective nature of the problem. Here we present a new approach that merges TCO physics to multi-objective evolutionary optimization algorithms. In contrast to conventional figure-of-merit relations, our approach discards any weighting-induced bias and hence provides accurate information on the material's performance. Moreover, it allows identifying optimization guidelines for many TCO structures. We show that once we envisage a device application (e.g. thin film solar cells) the analysis of the calculated Pareto-optimal set by data clustering techniques yields essential information on performance enhancement. Our approach opens the way towards multicriteria design of optoelectronic materials and devices.