Investigation of Manufacturing Parameters on the Mechanical Properties of Powder Metallurgy Magnesium Matrix Nanocomposite by Artificial Neural Networks

In present study, Artificial Neural Network (ANN) approach to prediction of the ODS Magnesium matrix composite mechanical properties obtained was used. Several composition of Mg- Al2O3 composites with four different amount of Al2O3 reinforcement with four different size of nanometer to micrometer were produced in different sintering times. The specimens were characterized using metallographic observation, microhardness and strength (UTS) measurements. Then, for modeling and prediction of mentioned conditions, a multi layer perceptron back propagation feed forward neural network was constructed to evaluate and compare the experimental calculated data to predicted values. In neural network training modules, different composition, sintering time and reinforcement size were used as input (3 inputs), hardness and Ultimate Tensile Strength(UTS) were used as output. Then, the neural network was trained using the prepared training set. At the end of training process the test data were used to check the system’s accuracy. As a result, the comparison of neural network output results with the results from experiments and empirical relationship has shown good agreement with average error of 2.5%. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3511

Epitaxial Interdigitated Back Contact (IBC) solar cell test platform for novel light trapping schemes

An Interdigitated Back Contact (IBC) solar cell is being developed for evaluation of emerging light trapping schemes of silicon nanowire arrays on pyramidal textured surfaces. The front surface of the baseline IBC cell design was optimized with a thin film coating considering both antireflection and passivation to reduce surface recombination. Addition of a front surface field (FSF) was shown to improve the surface passivation of the cell. PC2D simulations of the baseline device predict an efficiency of 17.4%. Silicon nanowire arrays and hybrid structures of silicon nanowires on pyramids were successfully fabricated. Hemispherical reflectance measurements show that a weighted average reflectance of just 1.89% was achieved. With adequate surface passivation, these highly-effective antireflective structures could result in a power conversion efficiency increase compared to traditional light trapping methods when incorporated into the IBC cell

Artificial Neural Network prediction of Cu–Al2O3 composite properties prepared by powder metallurgy method

AbstractArtificial Neural Networks (ANNs) are excellent tools for prediction of complex processes that have many variables and complex interactions. In the present study, the properties of copper based composite prepared from sintering of mechanically alloyed powders, were predicted using Artificial Neural Network (ANN) approach. In order to prepare copper based composites, copper powder with four different amounts of Al2O3 reinforcement (1, 1.5, 2, 2.5wt%) were mechanically alloyed and the consolidated compacts of prepared powders were sintered in five different temperatures of 725–925°C at seven several sintering times of 15–180min. Hardness and electrical conductivity measurements were performed to evaluate the properties of these composites. Then, for modeling and prediction of hardness and electrical conductivity, a multi layer perceptron back propagation feed forward neural network was constructed to evaluate and compare the experimental calculated data to predicted values. It was found that, in a given sintering temperature of 875°C, the electrical conductivity increases as the sintering time increases and the amount of Al2O3 reinforcement decreases. Also, increasing of reinforcement amount and sintering time in a given sintering temperature of 875°C leads to a decrease in hardness. Furthermore, electrical conductivity and hardness of specimens have shown a consistency with predicted results of ANN. These trained values had an average error of 3% and 5% for electrical conductivity and hardness values, respectively

28.81% efficient, low light intensity and high temperature sustainable ultra-thin IBC solar cell

The interdigitated back contact (IBC) structure for crystalline-silicon photovoltaic device has long been recognized as an effective technique to overcome the 25% efficiency barrier by shifting all the electrical conducting elements to the backside of the cell. For this structure, the architecture of material interlayer IBC electrodes is very important to reduce the recombination rate without affecting the work function at the metal-semiconductor interface for optimum dissolution and extraction of carriers from the absorber layer. Higher efficiency requires a balance between absolute crystal material and impurities in the semiconductor, doping concentration and PN Junctions, smart grid wires and intelligent sunlight capturing. In this work, the fabrication of a low light intensity functional and high cell temperature sustainable, IBC solar cell is investigated. Silicon-Heterojunction layer to absorb greater solar spectrum and interdigitated N/P contacts have been implemented, which grants the cell to receive full surface sunlight, results in 29% efficiency. Luminous-an optoelectronic device simulator has been utilized to construct a very thin cell with dimensions of 100×150pm. The effects of sunlight intensity and module temperature on the performance have been investigated and the parameters for the most efficient structure were found with 28.81% efficiency and 87. 68%fillfactor rate, making it ultra-thin, flexible and durable providing a wide range of operational capabilities

Junction formation with HWCVD and TCAD model of an epitaxial back-contact solar cell

In this paper, we present morphological and electrical characteristics of a junction formed of Si p-type films deposited on an n-type silicon wafer using a hot wire chemical vapor deposition (HWCVD) tool. We describe the fabrication process and study the influence of diborane flow and postprocess annealing in improving junction characteristics. Our morphological studies undertaken using atomic force microscopy show that the initial deposition suffered from voids rather than being a uniform film; however, this improves significantly under our annealing treatment. The improvement in morphology was observed in the electrical characteristics, with estimated Voc doubling and rectification of the junction improving by several orders of magnitude. Fitting of the current-voltage curves to a two-diode model showed that increasing the diborane flow in the process helps reduce the saturation current and ideality factors, while increasing the shunt resistance. Electrochemical capacitance-voltage (ECV) and quasi-steady-state photoconductance measurements are used to characterize the deposited films further. A solar cell device with a silicon epitaxy emitter is modeled using industry-standard 3-D modeling tools and input parameters from experimental data, and the impact of defects is studied. A potential efficiency approaching 25% is shown to be feasible for an optimized device

Single mode ridge waveguide using hybrid organic-inorganic sol-gel

Optical waveguides are structures that confine and direct optical signals in a region of higher effective index than its surrounding media. For integrated optics and photonic applications, it is often of importance to prepare waveguides in the form of thin film and channel structures. Hybrid sol-gel material is one of the interesting material in waveguide fabrication as it possess advantages such as low processing temperature, low fabrication cost, and ability of refractive index tuning. Main novelty of this research lies in the development of VTES based optical waveguides. Moreover, refractive index of selected material can be easily tuned by adjusting composition of TTBu in the synthesization stage. Behavior of light propagation and the confinement of light in a hybrid VTES based optical waveguide had been investigated. The characteristics of the waveguide had been simulated by BeamPropTM to obtain the optimum structure for waveguide fabrication. Planar slab waveguides and single mode straight waveguides had been fabricated using low cost photolithographic techniques and wet chemical etching processes. The properties of the hybrid sol-gel material and the fabricated waveguides had been characterized. The experimental results have demonstrated optical waveguiding in the sol-gel material. Attenuation of single mode optical waveguides at 1310 nm and 1550nm with waveguide losses of 1.6dB/cm and 6.7 dB/cm have been obtained respectively. Even though the losses are rather high, the VTES based hybrid sol-gel material is suitable as a waveguiding material in the optical interconnect situations by optimizing the fabrication process

Development of a HWCVD epitaxial IBC solar cell as a test platform for novel antireflection and light trapping schemes

Continuing to reduce the cost-per-watt is the key to providing affordable PV energy. In pursuit of reducing cost-per-watt of silicon PV, this work first focuses on the development of an all back contact silicon solar cell which incorporates a hot wire chemical vapour deposition (HWCVD) technique for p+ emitter deposition. This is as a simpler, lower cost alternative to the traditional high temperature diffusion processes. A proof-of-principle development batch is presented, which resulted in a device with low efficiency, however, through further characterisation, coupled with PC2D device modelling, various potential improvements to the design are identified. A detailed investigation into the as-deposited HWCVD emitter material reveals a polycystalline structure. Post-deposition annealing is shown to improve the crystallinity of the emitter but at the expense of a higher thermal budget. Good diode characteristics are demonstrated for the annealed p-type emitter on an n-type substrate. The focus then shifts to an experimental optimization of the front surface of the cell to achieve a low reflectance and low surface recombination, using conventional methods of thin film coating, pyramidal texturing and front surface field formation. The result is an improved device design and process listing which should result in a high efficiency baseline device on which further optimization can be carried out. A novel front surface antireflection scheme based on a two stage etch process that results in a hybrid nanowire-pyramid surface structure and a weighted average reflectance as low as 1.89% is then described. Conformal coating of the nanowires with alumina using atomic layer deposition is demonstrated, paving the way for effective passivation of these high surface area structures. Finally, a combination of finite difference time domain (FDTD) optical modelling and technology computer aided design (TCAD) electrical simulations predicts that a cell efficiency exceeding 20 % should be possible by combining an optimized HWCVD IBC process with a well-passivated hybrid nanowire-pyramid top surface antireflection scheme