This work introduces a new electrode geometry for making holes with high aspect ratios on AISI 304 using an electrical discharge drilling (EDD) process. In addition to commercially available cylindrical hollow electrodes, an elliptical electrode geometry has been designed, manufactured, and implemented. The principal aim was to improve the removal of debris formed during the erosion process that adversely affects the aspect ratio, dimensional accuracy, and surface integrity. The results were compared and discussed to evaluate the effectiveness of electrode geometry on the machining performance of EDD process with respect to the material removal rate (MRR,) the electrode wear rate (EWR), and the tool wear ratio (TWR). Dimensional features and surface characteristics of the drilled holes were also evaluated in aspects of overcut (OC), aspect ratio (AR), and surface roughness (SR). The experimental results revealed that an elliptical electrode is preferable for producing holes with good dimensional accuracy and improved surface quality. In addition, 3D models of flow field with liquid, gas, and solid phases are proposed for analyses of the interelectrode gap within the machining zone. Based on the results obtained from models, the elliptical electrode also exhibited good flushing capability for effective debris removal.
The charge species plays a vital role in changing the field in direct current discharge (DC). This article introduces a numerical modeling in one dimension of the inner electrode diameter of oxygen-fed negative corona discharge in coaxial electrodes geometry. The properties of negative corona plasma in a concentric cylindrical electrodes (wire-cylinder) were simulated by COMSOL Multiphysics software. Various diameters of negative corona electrode, namely 0.01, 0.025, 0.05, 0.075, and 0.125 mm, were applied, where the diameter of the outer cylindrical electrode was taken as 15 mm. The model was run at atmospheric pressure and the applied negative voltage was
-10 KV. Moreover, oxygen gas was used to fill the inter-electrodes dist
Aluminum doped zinc selenide ZnSe/n-Si thin films of (250∓20 nm) thickness with (0.01, 0.02 and 0.03), are depositing on the two type of substrate (glass and n-Si) to manufacture (ZnSe/n-Si) solar cell through using thermal vacuum evaporation procedure. physical and optoelectronic properties were examined for the samples. X-Ray and AFM techniques are using to study the structure properties. The energy band gap of as-deposited ZnSe thin films for changed dopant ratio were ranging from (2.6-2.68 eV). The results of Hall effect show that pure and doping films were (p-type), and the concentration carriers and the carriers mobility increases with increase Al-dopant ratio. The (C-V) have shown that the heterojunction were of abrupt type. In add
... Show MoreThe Sr doped La1Ba1-xSrx Ca2Cu4O8.5+δ samples with 0 ≤ x ≤ 0.3 had been prepared using the solid state reaction. The samples were claimed at 800°C for 3hr, palletized and sintered at 860°C for 20hr in air . Dielectric constant and loss by means of capacitance have been investigated with frequencies in the range of 1kHZ to 1MHZ for our samples at room temperature. Also, Shore hardness has been measured. The dielectric constant and loss decrease slightly with the increase of frequency for all compounds. Additionally, the partial substitution of Sr+2 into Ba+2 sites never have effect on the dielectric properties. X-ray diffraction (XRD) analysis showed a tetragonal structure and the
... Show MoreThe interacting boson models, and were used to perform a complete study of even –even 160-168Yb isotopes .The low –lying positive parity states, dynamic symmetries, reduced electric quadrupole transition probability , quadruple momentum , and potential energy surface for 160-168Yb were investigated. Energy level sequences and energy ratios showed the gradual transition of the properties of these nuclei from the γ-unstable features to the rotational features . Adding the pairing parameter to Hamiltonian had a very slight effect on this feature, but it raised the β band, since it represents symmetry breaking such as in γ-unstable features . This applie
... Show MoreThin films of Zinc Selenide ZnSe have been prepared by using thermal evaporation in vacuum technique (10-5Torr) with thickness (1000, 2700, 4000) A0 and change electrode material and deposited on glass substrates with temperature (373K) and study some electrical properties at this temperature . The graphs shows linear relation between current and voltage and the results have shown increases in the value of current and electrical conductivity with increase thickness and change electrode material from Aluminum to Copper
This thesis was aimed to study gas hydrates in terms of their equilibrium conditions in bulk and their effects on sedimentary rocks. The hydrate equilibrium measurements for different gas mixtures containing CH4, CO2 and N2 were determined experimentally using the PVT sapphire cell equipment. We imaged CO2 hydrate distribution in sandstone, and investigated the hydrate morphology and cluster characteristics via μCT. Moreover, the effect of hydrate formation on the P-wave velocities of sandstone was investigated experimentally.
Storing, transferring, and processing high-dimensional electroencephalogram (EGG) signals is a critical challenge. The goal of EEG compression is to remove redundant data in EEG signals. Medical signals like EEG must be of high quality for medical diagnosis. This paper uses a compression system with near-zero Mean Squared Error (MSE) based on Discrete Cosine Transform (DCT) and double shift coding for fast and efficient EEG data compression. This paper investigates and compares the use or non-use of delta modulation, which is applied to the transformed and quantized input signal. Double shift coding is applied after mapping the output to positive as a final step. The system performance is tested using EEG data files from the C
... Show MoreDiode lasers are becoming popular in periodontal surgery due to their highly absorption by pigments such as melanin and hemoglobin their weak absorption by water and hydroxyapatite makes them safe to be used around dental hard tissues. Objective: The aim of the present study was to evaluate the efficiency of diode laser in performing gingivectomy in comparison to conventional scalpel technique in patients with chronic inflammatory enlargement. Materials and methods: Thirty patients were selected for this study. All of them required surgical treatment of gingival enlargements and were randomly divided into two groups: Control group (treated by scalpel and include sixteen patients) and study group (treated with diode laser 940nm and includ
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