Studies of the degradation behaviour of Gamma-TiAl and Fe3Al intermetallics

The oxidation behaviour of Fe3A1 intermetallic alloys with and without reactive element (RE) and Ti-46.7A1-1.9W-0.5Si alloy over the temperature ranges of 900 to 1100°C and 750 to 950°C respectively were studied for up to 240h. The isothermal and cyclic oxidation behaviour of Fe3A1 intermetallic materials was studied in static air. The Al203 adherence of (Y and/or Hf)-doped Fe3A1 alloys was examined using newly developed — by the researcher — cyclic oxidation rig built in AMRI's laboratory. However the oxidation of Ti-46.7A1-1.9W-0.5Si alloy was studied in air and under Ar-02 atmospheres of three oxygen partial pressures; P02 = (0.05, 0.2 and 0.8) x 105 Pa. Isothermal sulphidation/oxidation work of coated — with specially designed single and multi- layer coatings — and uncoated Ti-46.7A1-1.9W-0.5Si alloy was performed in relatively high partial pressure of sulphur (pS2 = 6.8 x 10-1 Pa) and low partial pressure of oxygen (p02 = 1.2 x 10-15 Pa) at 850° C for up to 240h. Characterisation of the specimens was conducted using SEM, EDX, and XRD techniques. Higher oxidation rates of Ti-46.7A1-1.9W-0.5Si alloy were observed in air than in Ar-20%02 at all temperatures. The scale formed in air consisted of Ti02/Al203/Ti02/TiN/TiAl2/substrate, whilst the scale developed in Ar-20%02 atmosphere was comprised of Ti02/Al203/Ti02/Al203/Ti3A1/substrate. The oxidation rates of Ti-46.7A1-1.9W¬0.5Si alloy increased with decreasing the oxygen partial pressure in Ar-02 atmospheres at the entire range of temperatures. The employment of single A1TiN and CrN single layer coatings improved the sulphidation/oxidation behaviour of Ti-46.7A1-1.9W-0.5Si alloy at 850°C for up to 240h in H2/H20/H2S gas mixture. However, the use of NbN and CrN diffusion barrier coatings significantly enhanced its corrosion resistance. The scale on uncoated Ti-46.7A1-.9W-0.5Si alloy in sulphidising/oxidising atmosphere consisted of Ti02/Al203/TiS+W/TiA13/TiAl2/substrate. The reactive element (RE) — Y and/or Hf — addition especially Y significantly improved the oxide adherence of Fe3A1 over the specified range of temperature and exposure time (or cycles). However, higher oxidation rate of Fe3A1 alloys doped with Y was obtained under both isothermal and cyclic oxidation. Although the scale thickness of Hf-doped alloy was always higher than that of Y-doped alloys, the oxidation rate constant of the later is found in some cases to be less than that of the first by one order of magnitude. However, the scale on the Hf-doped alloy is relatively adherent to the substrate if compared with the scale of undoped Fe3A1 alloy even at the areas where oxide pegs were observed on Fe3A1-Hf alloy. Generally, no conclusion could be taken from the kinetic data of Fe3A1 alloys regarding the reactive element effect (REE) due to the intergranular attack on the Y-containing alloys. Improving the interface properties by RE addition led to a better control of the outward diffusion of aluminium and eliminated the detrimental effect of sulphur (possibly present in the Fe3A1 alloys). However, the presence of the RE in the alloy led to the formation of coherent scales. At 1100°C and after prolonged exposure, the scale of RE- doped alloys was not able to remain in contact with the substrate especially under thermal cycling conditions. The external scale severely cracked especially at places where oxide ridges were formed. The Y-containing Fe3A1 alloys were capable of producing another thin and adherent scale underneath the cracked external scale

Video Encryption Based on Chaotic Systems in the Compression Domain

With the development of the internet and multimedia technology digital video encryption has attracted a great deal of research interest in the recent few years in applications. In this paper, we propose a method to encrypt video data. The proposed algorithm is based on the MPEG video coding standard. It selectively encrypts some DCT coefficients in the I frame, B frame and P frame in MPEG video compression by using chaotic systems. The key in this paper is chaotic sequence based on logistic mapping. It can produce the pseudo-random sequences with good randomness. The experimental results based on chaotic maps prove the effectiveness of the proposed method, showing advantages of large key space and high-level security. The proposed algorithm was measured through a series of tests and achieved good results. The results indicate that the algorithm can be implemented for video encryption efficiently and it provides considerable levels of security

The Effect of Cadmium Doping on Bscco Superconductors Prepared Via Coprecipitation Method

The coprecipitation technique was used in the preparation of cadmium doped Bi1.6Pb0.4Sr2Ca2Cu3O10 and Bi1.7Pb0.3Sr2Ca2Cu3O10 polycrystalline ceramic superconductors. In this study, the calcium site was subjected to Cd doping with nominal composition ranging from x=0 to x=0.1 at different sintering times. The superconducting properties of the samples have been investigated. The undoped samples, which exhibits TC(R=0) around 102 –104 K and TC-onset around 112-116 K, showed large flaky grains around 9-11 m in size which are randomly distributed. However, at longer sintering time (100 h) the undoped sample showed a better orientation as compared to that of the shorter sintering time (24 hr) sample. The calculated value of Josephson current, Io, obtained from the AC susceptibility data showed a much higher value (Io =100.04 A) as compared to the sample prepared by conventional method (Io =55.9 A). This indicates better grain connectivity and higher 2223 phase content, which was confirmed by SEM photographs. In addition, the nature of the ultra fine particles of the oxalate powders produced by coprecipitation method have increased the diffusion reaction and shortened the heat treatment procedure for the sample preparation, this leads to better superconducting properties as compared to the samples prepared by conventional solid state technique where its diffusion reaction requires high sintering temperatures for long duration and sometimes several grindings. The resistivity measurements showed the normal metallic behaviour followed by decreased in TC(R=0) as the cadmium concentration increased due to the decrease in the 2223 phase and an increase in the formation of 2212 phase. The temperature dependence of ac susceptibility data, shows the shifting of the onset diamagnetism towards lower temperature as the Cd concentration increased due to the presence of low-TC phase. The imaginary component, shows a shift in the intergranular coupling peak, Tp, towards lower temperature as the Cd concentration increased. Hence it can be deduced that the dynamic magnetic response of the samples are not only phase dependent but also dependant on the intergranular coupling. The calculated I0 which revealed the quality of the coupling of the grains, showed a decrease in its value as the cadmium concentration increased. The results of x-ray diffraction (XRD) patterns show that all samples doped with Cd contain 2212 peaks which correspond to the low-superconducting phase. The intensity of these peaks increases towards higher value, as the Cd concentration increases. The volume of 2223 phase decreases gradually as the Cd concentration increases. In addition, there is a possibility that either Cd2+ might have occupied other sites in the sample. When long sintering time was applied, the improvement in superconducting properties was obvious at low doping concentrations x=0.02 where the sample was still dominated by 2223 phase. Above that concentration, the grain size decreased and became shorter and thicker, randomly distributed as compared to the undoped samples. It is also observed that the superconducting properties and the microstructure improved when the sample was sintered for 48 hours and 100 hours, the high-TC phase dominates, indicating that the optimum time must be above 48 hours. The study shows that the substitution of cadmium in calcium site does not improve the TC of the BSCCO system. This is due to the formation of low-TC phase which weakened the coupling of the grains. However, all samples showed an obvious improvement in TC as the sintering time increases

A survey of weeds present in AL- Qatten Diroctorate Farms Hadhramout Governorate

An exclusive study of weeds present in Alqatten Directorate farms, was carried out this study aimed to identify types and number of weeds in the farms. The study area included (20) Farms in five different regions. 39 plant species belonging to 20 plant Family have been identified. Grassy famil was the most present with 7 species. the most wide spread grass was, Cynodon dactylon and Setaria verticillata; as they were found in all studied farms. While Withania somnifera and Rhazya stricta, were less prevalent, as they were present in two farms only.The study reveals that there is defference in the number of weed plants in the farms studied. The high number of weed types was found at Hasinat1 farm in Algatten area, where (27) type were found . the minimum number of weeds was found in Alaneen area, at Achariqih farm, where (14) types only were found

Effect of Different Operational Conditions on the Treatment Performance of Milk Processing Wastewater (MPW) Using a Single Stage Flexible Fibre Biofilm Reactor (SS-FFBR)

The performance of a biofilm system, single-stage flexible fibre biofilm reactor (SS-FFBR) treating milk processing wastewater (MPW) is evaluated under various process and operational conditions. The system behavior is analyzed with different biological and physical parameters. Results show that the high COD removal efficiency of 95% is obtained at a low CODin concentration of 809 mg/L. However, the COD removal is slightly decreased to 91.7% once the CODin concentration incremented to nearly 4000 mg/L. The effect of organic loading rate (OLR) on the SS-FFBR performance is examined as total suspended solids removal efficiency, dissolved oxygen, and turbidity. The SS-FFBR showed considerable performance, so that 89.9% and 89.7% removal efficiencies in terms of COD and TSS removals, respectively, obtained at the highest OLR of 11.7 kg COD/m3d. TSS removal efficiency of 96.7% is obtained at a low OLR of 1.145 kg COD/m3d. A linear relationship between the OLR and COD removal rate was revealed. The COD removal rate was incremented from 1.08 to 10.68 kg COD/m3d as the OLR increased from 1.145 to 11.7 kg COD/m3d. Finally, the operating system is a promising technique recommended to treat various industrial wastewaters with high OLR

Prevalence and risk factors associated with Entamoeba Histolytica infection among children in Sebha, Libya

Background: The protozoa parasite Entamoeba histolytica is an important cause of human morbidity and mortality worldwide besides malaria and schistosomiasis. Prevalence of E. histolytica in Sebha, Libya has been scantily studied and risk factors associated with this parasite are unavailable in Libya. Aims: A cross-sectional study was aimed to provide the first data on the prevalence and epidemiological risk factors associated with E. histolytica infection among school children in Sebha, Libya. Subjects and Methods: A total of 150 stool samples randomly were collected (during period from April 2017 to May 2017) from school children residents of Sebha and examined by direct smear microscopy (in normal saline and iodine smears) for the detection of E. histolytica infection. Results: Of one hundred fifty children, six children (4%) were found to be infected with this parasite. Boys were more significantly (P 0.05). It has been noted that those who had large family size have significantly (P < 0.05) higher risk of being infected with E. histolytica. A significant (P < 0.05) association was found between education level of children's parents and E. histolytica exposure among children. No, significant correlation was found between monthly income of family and the presence of E. histolytica infection among children. Conclusions: Prevalence of E. histolytica among school children is low and this parasite may play a minor role in causing morbidity in this population in Sebha, Libya. Large size of families and education of parents of children were significant predictors of this parasite. In addition, more studies are needed to provide data on epidemiological risk factors of E. histolytica to improve health education and environmental sanitary conditions to protect children from the infection of this parasite in Libya

Enhancement in performance and self-cleaning properties of PES membrane surface tailored by modified TiO2

In this study, the polyethersulfone (PES) membranes were established by surface modification using C, N codoped-TiO2/WO3 (LTW) photocatalytic nanocomposite to amelioration of the membrane performance in terms of antifouling and self-cleaning properties. The nanocomposite membranes were characterized by ATR-FTIR, SEM, AFM, and water contact angle (WCA). The photocatalytic membranes' performance was evaluated using assessment of the pure water flux (PWF), antifouling behavior, photoactivity, and long-term filtration. The membrane modification improved morphology and hydrophilicity of the membranes surface, contributing to the enhanced permeability (PWF of 49.65 kg/m2.h), and substantial antifouling property (FRR of 96.96 %) as well as photoactivity (94.36 % dye removal) of the optimal photocatalytic membrane (M3 membrane). The long-term filtration of the optimal membrane represented its high performance and noteworthy antifouling resistance

Power management and sizing optimization for hybrid grid-dependent system considering photovoltaic wind battery electric vehicle

Energy Management Strategy (EMS) as a control strategy for microgrid (MG) systems is a complex task to operate the integrated power systems and utilize consumer-based. Alternative energy sources such as solar and wind can be used to generate energy that can be used to power electrical appliances when combined with energy storage units. Additionally, with other sources to complement the drawbacks of each source. But the common drawback of the aforementioned sources are naturally unpredictable and climatology changes dependent. The main aim of this study is to minimize the cost and losses of the system, contrary, maximizing the renewability. This study considers a Tripoli-Libya as a case study located in the north of Libya and coordinated between32.88o N latitude and 13.19o E longitude. The system utilizes night-Time for exchanging the power between the Electric Vehicle (EV) and the utility grid to form Vehicle-To-Grid (V2G) technology. The result of the study shows that the Cost of Energy (COE), Renewable Energy Fraction (REF), and Deficiency Power Supply Probability (DPSP), are an objective of the study along with the analysis of collected data based on the Grasshopper Optimization Algorithm (GOA) using Matlab. The acquired result for the sizing system configuration has been validated with nature-inspired metaheuristic algorithms

Suspension System Control Process for Buses with In-Wheel Motors

In the last few years, there has been considerable growth in in-wheel electric motors manufacturing and the number of electric buses operating around the world. As a result of this clear increase, competition between electric bus manufacturers is increasing to reach the best satisfaction and comfort for passengers. This paper aims to deliver significantly better results due to suspension system. This paper also aims to evaluate an active bus suspension system with an in-wheel electric motor and to show the effect of this motor on the performance of the bus’s suspension system. In this work, a quarter bus suspension system is simulated and modelled using Matlab software, in addition to using one of the well-known control technologies, which is the linear quadratic regulator (LQR). The results showed that the weight of the electric motors in the bus’s wheels had a slightly negative effect on passenger comfort, as the reason for this effect is because the electric motor increased the mass of the wheel