Zedan Y.,Boulevard Of Luniversite |
Alkahtani S.,Al Kharj University
Journal of Materials Processing Technology | Year: 2013
This study was conducted with the intention of investigating a new experimental alloy, namely the 396 alloy which belongs to the Al-Si near-eutectic cast alloy group and contains about 10.8%Si. In the light of the above, the main purpose of the work is to report on the changes observed in the mechanical and machinability criteria resulting from the effects of the presence of two levels of Cu, namely 2.25% and 3.5%; and of the effects of two levels of Mg, namely 0.3% and 0.6%. In addition to the preceding, the effects of Mg-free alloys and Sr-modification on these same alloys were also investigated. The results demonstrate that the increase in the levels of Cu and/or Mg in the 396-T6 alloy has a detrimental effect on drill life. Such an effect may be attributed to the formation of large amounts of the coarse blocklike Al 2Cu phase, together with the formation of thick plates of the Al-Si-Cu-Mg phase. The Mg-free experimental alloy displays the lowest cutting force and moment in addition to producing the highest number of holes in the alloys studied. This observation may be explained by the cooperative precipitation of the Al 2Cu, Mg 2Si, Al 2CuMg, and Al 5Si 6Cu 2Mg 8 hardening phases in Mg-containing alloys which confer greater strength on the alloy than would be the case with the precipitation of only the Al 2Cu phase in the Mg-free alloy. A comparison of the non-modified alloy and the Sr-modified alloy (containing the same level of Mg and Cu additions) in terms of the number of holes drilled, reveals that the morphology of Si particles has a noticeable effect in governing the tool life of near-eutectic Al-Si alloys. The chip breakability of the alloys containing the Al 2Cu phase is superior to that of the alloys containing Mg 2Si. Thus, combined additions of Cu and Mg are expected to further refine the size of the chips produced. © 2012 Elsevier B.V.
Mohamed H.A.E.,Al Kharj University
Communications in Computer and Information Science | Year: 2011
Knowledge acquisition continues to be a challenging and time consuming task in building decision support systems. Rule induction is a data mining process for acquiring knowledge in terms of decision rules from a number of specific 'examples' to explain the inherent causal relationship between conditional factors and a given decision. This paper introduces a method of rules extraction for fault diagnosis based on rough set theory and decision network. The fault diagnosis decision system attributes are reduced firstly, and then a decision network with different reduced levels is constructed. Initialize the network's node with the attribute reduction sets and extract the decision rule sets according to the node of the decision network. In addition, the coverage degree and the certainty factor were applied to filter noise and evaluate the extraction rules. The proposed methodology cannot only set up rational and succinct diagnosis model for large complicated power system but also it can dispose uncertainty information of substation and get correct diagnosis result under incomplete information. At last an example is given; the result indicates that the method can diagnosis single fault and multi-fault efficiently and could be used to assist operators in their decision-making processes. © 2011 Springer-Verlag.
Yassin A.E.B.,King Saud University |
Khalid Anwer M.D.,Al Kharj University |
Mowafy H.A.,King Saud University |
El-Bagory I.M.,King Saud University |
And 2 more authors.
International Journal of Medical Sciences | Year: 2010
Solid lipid nanoparticle (SLNs) formulae were utilized for the release of 5-fluorouracil (5-FU) inside the colonic medium for local treatment of colon cancer. SL Ns were prepared by double emulsion-solvent evaporation technique (w/o/w) using triglyceride esters, Dynasan™ 114 or Dynasan™ 118 along with soyalecithin as the lipid parts. Different formulation parameters; including type of Dynasan, soyalicithin: Dynasan ratio, drug: total lipid ratio, and polyvinyl alcohol (PVA) concentration were studied with respect to particle size and drug entrapment efficiency. Results showed that formula 8 (F8) with composition of 20% 5 -FU, 27% Dynasan™ 114, and 53% soyalithicin and F14 (20% 5-FU, 27% Dynasan™ 118, and 53% soyalithicin), which were stabilized by 0. 5% PVA, as well as F10 with similar composition as F8 but stabilized by 2% PVA were considered the optimum formulae as they combined small particle sizes and relatively high encapsulation efficiencies. F8 had a particle size of 402.5 nm ± 34.5 with a polydispersity value of 0.005 and an enca psulati on efficiency of 51%, F10 had a 617. 3 nm ± 54. 3 particle size with 0.005 polydispersity value and 49.1% encapsulation efficiency, whereas formula F14 showed a particle size of 343 nm ± 29 with 0.005 polydispersity, and an encapsulation efficiency of 59. 09%. DS C and FTIR results suggest ed the existence of t he lipids in the solid crystalline state. Incomplete biphasic prolonged release profile of the drug from The three formulae was observed in phosphate buffer p H 6. 8 as well as simulated colonic medium containing rat caecal contents. A burst release with magnitudes of 26%, 32% and 28.8% cumulative drug released were noticed in the first hour samples incubated in phosphate buffer p H 6. 8 for both F8, F10 and F14, respectively, followed by a slow release profile reaching 50%, 46.3% and 52% after 48 hours. © Ivyspring International Publisher.
Alafeefy A.M.,Al Kharj University
Journal of Saudi Chemical Society | Year: 2011
A series of some new 2,3-disubstituted-6-iodo-3H-quinazolin-4-one derivatives was prepared and screened for their in vitro antitumor activity against the human breast cancer cell line (MCF-7), human cervix carcinoma cell line (HeLa), human liver cancer cell line (HepG2) and human colon cancer cell line HCT-8. Five compounds exhibited broad spectrum antitumor activity, better than the standard drug Doxorubicin (CAS-23214-92-8) against the four tested cell lines. In the present study, MCF-7 cell line was the most sensitive one, 12 compounds were good cytotoxic towards it. The best cytotoxic results were obtained with compounds bearing allyl and/or benzyl moiety at positions 2 and/or 3 of the quinazoline nucleus. © 2011 King Saud University.
Mohamed H.A.E.,Al Kharj University
Communications in Computer and Information Science | Year: 2011
Rough set theory is a relative new tool that deals with vagueness and uncertainty inherent in decision making. In this paper we suggest a new rough algorithm for reducing dimensions and extracting rules of information systems using expert systems. This paper introduces a probabilistic rough set approach to discover grade rules of transformer evaluation when there is a missing failure symptom of transformer. The core of the approach is a soft hybrid induction system called the Generalized Distribution Table and Rough Set System (GDT-RS) for discovering classification rules. The system is based on a combination of Generalized Distribution Table (GDT) and the Rough Set methodologies. With every decision rule two conditional probabilities associated, namely the certainty factor and the coverage factor. The probabilistic properties of the Decision rules are discussed. © 2011 Springer-Verlag.
El-Sousy F.F.M.,Al Kharj University
IET Electric Power Applications | Year: 2011
This study proposes a hybrid supervisory H∞ control system using a recurrent cerebellar model articulation controller (RCMAC) for achieving high precision position tracking performance of permanent-magnet synchronous motor (PMSM) servo drive. The hybrid control system is composed of a RCMAC, a supervisory controller and a robust H∞ controller. The RCMAC is used as the main position tracking controller to mimic a perfect computed torque control law, and the robust H∞ controller is designed with adaptive bound estimation algorithm to compensate for the approximation error between the RCMAC and the ideal controller. The supervisory controller is designed based on the uncertainty bound of the PMSM to stabilise the system states around a predefined bound region and achieve satisfactory tracking performance. The online adaptive control laws are derived based on the Lyapunov stability analysis, so that the stability of the system can be guaranteed. A computer simulation is developed and an experimental system is established to validate the effectiveness of the proposed hybrid control system. All control algorithms are implemented in a TMS320C31 digital signal processor-based control computer. The simulated and experimental results confirm that the proposed hybrid control system grants robust performance and precise response regardless of load disturbances and PMSM parameters uncertainties. © 2011 The Institution of Engineering and Technology.
El-Sousy F.F.M.,Al Kharj University
Journal of Power Electronics | Year: 2010
In this paper, an intelligent sliding-mode speed controller for achieving favorable decoupling control and high precision speed tracking performance of permanent-magnet synchronous motor (PMSM) drives is proposed. The intelligent controller consists of a sliding-mode controller (SMC) in the speed feed-back loop in addition to an on-line trained wavelet-neural-network controller (WNNC) connected in parallel with the SMC to construct a robust wavelet-neural-network controller (RWNNC). The RWNNC combines the merits of a SMC with the robust characteristics and a WNNC, which combines artificial neural networks for their online learning ability and wavelet decomposition for its identification ability. Theoretical analyses of both SMC and WNNC speed controllers are developed. The WNN is utilized to predict the uncertain system dynamics to relax the requirement of uncertainty bound in the design of a SMC. A computer simulation is developed to demonstrate the effectiveness of the proposed intelligent sliding mode speed controller. An experimental system is established to verify the effectiveness of the proposed control system. All of the control algorithms are implemented on a TMS320C31 DSP-based control computer. The simulated and experimental results confirm that the proposed RWNNC grants robust performance and precise response regardless of load disturbances and PMSM parameter uncertainties.
Ahmad S.,Al Kharj University
Journal of Clinical and Diagnostic Research | Year: 2010
Objectives: The aim of this study was to determine the prevalence of the nasal carriage of Staphylococcus aureus among healthcare workers (HCWs) at a Specialist Hospital and to detect the antibiotic susceptibility of S. aureus. Material and Methods: This cross-sectional study was conducted from January to April, 2007. Nasal swabs were taken from 352 randomly selected HCWs. The isolates were identified as S. aureus based on morphology, Gram stain, catalase test, coagulase test, and mannitol salt agar fermentation. The sensitivity of the isolates was carried out by the modified Kirby Bauer method. Results: A total of 352 subjects comprising medical doctors, nurses, cleaners and the administrative staff of a Specialist Hospital, who worked in or frequently visited the nursery, maternity, paediatric, medical, surgery and intensive care wards during January to April 007 were tested for the carriage of Staphylococci. 204 of them (58.0%) were males and 148(42%) were females. 313 (89%) subjects were doctors, nurses and cleaners and 39 (11%) were administrative personnel. Of the total 352 samples, S. aureus was isolated from 112 (31.8%) specimens. Of these 112 S. aureus isolates, 103 (92%) were found to be methicillin sensitive S. aureus (MSSA) and 9 (8%) were found to be methicillin resistant S. aureus (MRSA).The rate of S. aureus in males and females were 23.0% and 46.0%, respectively. The rate of S. aureus in the medical staff, nurses, cleaners and administrative personnel were 35.5% and 2.6%, respectively. The prevalence of the carriage was higher (30.1-33.4%) in young persons, i.e. less than 35 years than (6.8-15.7%) those aged 35-55 years or above. Most of the MSSA strains were susceptible to tested agents except penicillin, ampicillin, gentamicin and erythromycin. A majority of the MRSA isolates showed multiple drug resistance. All MSSA and MRSA isolates were fully sensitive to Vancomycin. Conclusion: A high rate of the carriage of S.aureus in this hospital, with a large proportion of strains being resistant to penicillin and the isolation of MRSA strains from these carriers calls for periodic surveillance of nosocomial infections due to S.aureus and other important bacterial pathogens.
Husain Khan T.,Al Kharj University |
Husain Khan T.,Jamia Hamdard University |
Sultana S.,Jamia Hamdard University
Toxicology Mechanisms and Methods | Year: 2011
In this study, we examined the inhibitory effects of Aegle marmelos methanolic extract on diethylnitrosamine (DEN) initiated and 2-acetyl aminofluorene (2-AAF) promoted liver carcinogenesis in male Wistar rats. Interestingly, it was found that A. marmelos (25 and 50 mg/kg body weight) resulted in a marked reduction of the incidence of liver tumors, which was further confirmed with histopathology. Furthermore to understand the underlying mechanisms of chemoprevention potential of A. marmelos, we evaluated the levels of hepatic antioxidant defence enzymes, ornithine decarboxylase (ODC) activity and hepatic DNA synthesis as a marker for tumor promotion since a direct correlation between these marker parameters and carcinogenicity have been well documented. Treatment of male Wistar rats for five consecutive days with 2-AAF induced significant hepatic toxicity, oxidative stress and hyper-proliferation. Pretreatment of A. marmelos extract (25 and 50 mg/kg body weight) prevented oxidative stress and toxicity by restoring the levels of antioxidant enzymes at both the doses. The promotion parameters (ODC activity and DNA synthesis) induced by 2-AAF administration in diet with partial hepatectomy (PH) were also significantly suppressed dose-dependently by A. marmelos. Therefore, we can conclude that ultimately the protection against liver carcinogenesis by A. marmelos methanolic extract might be mediated by multiple actions, which include restoration of cellular antioxidant enzymes, detoxifying enzymes, ODC activity and DNA synthesis. © 2011 Informa Healthcare USA, Inc.
El-Sayed K.M.,Al Kharj University |
Khalil H.,King Saud University
International Journal of Oral and Maxillofacial Surgery | Year: 2010
Alveolar bone grafting is a standard method for treating alveolar cleft. To ensure the best outcome, improving the arch form as well as soft tissue quality in the area around the cleft is recommended. In this study, 11 patients who presented with alveolar cleft and collapsed maxillary arch were treated in the following sequence: transpalatal distraction osteogenesis followed by soft tissue surgery in some cases and by cancellous bone graft. In all cases, transpalatal distraction osteogenesis successfully corrected the transverse maxillary deficiency. One case showed a complete loss of the bone graft. Other minor complications were reported but they did not affect the final outcome. © 2010 International Association of Oral and Maxillofacial Surgeons.