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Search Results: 1 - 10 of 478115 matches for " Nathera A. Ali "
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Distances Scale Determination for a Planetary Nebula in Galactic Bulge  [PDF]
Sundus A. Abdullah, Nathera A. Ali, Mohamed A. Sallih
International Journal of Astronomy and Astrophysics (IJAA) , 2013, DOI: 10.4236/ijaa.2013.32008
Abstract:

Planetary Nebulae (PN) distances represent the fundamental parameter for the determination the physical properties of the central star of PN. In this paper the distances scale to Planetary Nebulae in the Galactic bulge were calculated related to previous distances scales. The proposed distance scale was done by recalibrated the previous distance scale technique CKS/D82. This scale limited for nearby PN (D ≤ 3.5 kpc), so the surface fluxes less than other distance scales. With these criteria the results showed that the proposed distance scale is more accurate than other scales related to the observations for adopted sample of PN distances, also the limit of ionized radius (Rio) for all both optically thick and optically thin in the rang of sizes (0.45 > Rio (pc) > 0.03).

Study the Effect of Irradiation Time and HF Concentration on Porosity of Porous Silicon and Study Some of the Electrical Properties of Its Based Device  [PDF]
Nathera Abass Ali Al-Temeeme, Ghaida Salman Muhammed
Advances in Materials Physics and Chemistry (AMPC) , 2012, DOI: 10.4236/ampc.2012.21009
Abstract: Porous silicon has been produced in this work by photochemical etching process (PC).The irradiation has been achieved using ordinary light source (150δ250 W) power and (875 nm) wavelength. The influence of various irradiation times and HF concentration on porosity of PSi material was investigated by depending on gravimetric measurements. The I-V and C-V characteristics for CdS/PSi structure have been investigated in this work too.
The Effect of Zn Concentration on the Optical Properties of Cd10–xZnxS Films for Solar Cells Applications  [PDF]
Nathera A. Al-Tememee, Nada M. Saeed, Sundus M. A. Al-Dujayli, Baha T. Chiad
Advances in Materials Physics and Chemistry (AMPC) , 2012, DOI: 10.4236/ampc.2012.22012
Abstract: In this paper, Cd10–xZnxS (x = 0.1, 0.3, 0.5) films were deposited by using chemical spray pyrolysis technique, the molar concentration precursor solution was 0.15 M/L. Depositions were done at 350?C on cleaned glass substrates. X-ray diffraction technique (XRD) studies for all the prepared film; all the films are crystalline with hexagonal structure .The optical properties of the prepared films were studied using measurements from VIS-UV-IR spectrophotometer at wave-length with the range 300 - 900 nm; the average transmission of the minimum doping ratio (Zn at 0.1%) was about 55% in the VIS region, it was decrease at the increasing of Zn concentration in the CdS films, The band gap of the doped CdS films was varied as 3.7, 3.8, 3.6 eV at x = 0.1, 0.3 and 0.5 respectively.
Ultrastructural Identification of the Basal-Granulated Cells in the Duodenum of Albino Rat  [PDF]
Ali Hassan A. Ali
Open Journal of Gastroenterology (OJGas) , 2014, DOI: 10.4236/ojgas.2014.47041
Abstract: The fine structure of the crypt epithelium of the duodenal mucosa in albino rats was studied to represent the types and distribution of the basal-granulated or endocrine cells. Twenty male animals were used. Perfusion-fixation was made and samples of duodenal mucosa were taken and processed to prepare epon-embedded specimens for examination by a transmission electron microscope. Cells containing membrane-bound granules were seen in the crypt epithelium. They were identified to be basal-granulated cells. Six different types of such cells were demonstrated. All of the cells were of the closed type. The possible functional significance of these closed cell types was discussed. Correlation among the distributions of such cells in the intestine of albino rat might enable the physiologists, internists and other research workers to study several biologically active peptides with well-established functions other than those which have long been investigated.
Hepatoprotective Effect of Green Tea Extract against Cyclophosphamide Induced Liver Injury in Albino Rats  [PDF]
Ali Hassan A. Ali
Forensic Medicine and Anatomy Research (FMAR) , 2018, DOI: 10.4236/fmar.2018.62002
Abstract: Background: Green tea intake is accompanied with a lower incidence of cardiovascular disease, cancer and neurodegenerative disorders; hence green tea extract has been included as dietary supplement along with other supplements and multivitamins. Aim of the Work: Studying the effect of cyclophosphamide administration on the liver of adult male albino rats and the possible protective role of green tea extract. Material and Methods: The current study was carried out on 45 adult male albino rats. They were divided into three equal groups (each included 15 rats). Group I (control group) was injected intraperitoneally with normal saline at a dosage of 0.5 mg/kg body weight twice weekly for 9 weeks. Group II was injected intraperitoneally with cyclophosphamide (CP) (150 mg/kg/day) for two weeks. Group III: rats received green tea extracts orally (50 mg/kg/day) for three weeks, and then continued for further two weeks concomitantly with intraperitoneally cyclophosphamide (CP) injected (150 mg/kg/day). Results: Rats exposed to cyclophosphamide (CP) showed several histological and histochemical changes in their liver. These changes were improved by using green tea. Conclusion: The present work showed that green tea had preventive and therapeutic effect upon livers of albino rats after they were exposed to CP.
Positioning with Wide-Area GNSS Networks: Concept and Application  [PDF]
Tarig A. Ali
Positioning (POS) , 2012, DOI: 10.4236/pos.2012.31001
Abstract: The use of Global Navigation Satellite Systems (GNSS) for positioning has revolutionized the way location data is be- ing collected. The NAVigation System with Time And Ranging Global Positioning System (GPS), which is a principal component of the global navigation satellite system (GNSS); is a satellite-based radio navigation system that provides positions of points of interest and time information to users. GPS positional accuracy can be improved by using differential corrections obtained through a technique called Differential GPS (DGPS), which is known to provide the most accurate positioning results. Differential correction can be applied in real time at the data collection phase or in the of- fice, at the post-processing phase. DGPS is generally used for positioning purposes through static or kinematics GPS surveys. In static GPS surveys, one receiver is placed at a point whose coordinates are known and the other receiver is placed over a point whose coordinates are desired. In kinematic surveys, one receiver remains at one point (base station) normally with known coordinates, and the other receiver (rover) moves from point to point in the project area. Kinematic surveys in which points positions are computed on-the-fly (OTF) are known as real-time kinematic (RTK). RTK surveys provide real-time locations of points of interest needed in many applications. Positioning with wide-area GNSS networks is basically based on the DGPS and RTK concepts. Observables from a network of a finite number of GPS receivers over an area are processed by a server at a central location (network server) and made available to the users of the network later or in real-time through radio-based, satellite, or wireless communications. This article provides a review of the concept and application of positioning with wide-area GNSS networks.
An Error Modeling Framework for the Sun Azimuth Obtained at a Location with the Hour Angle Method  [PDF]
Tarig A. Ali
Positioning (POS) , 2012, DOI: 10.4236/pos.2012.32004
Abstract: Sun observations provide a robust way for determining the geodetic or true azimuth at a location. Azimuth is generally defined as the angle in the plane measured from the meridian’s north (or south) to the location of the line of interest. It is common to use the north azimuth; also referred to as “azimuth”, especially in civilian surveying applications. The astronomic meridian is obtained through astronomic observations of the Sun or North Star (Polaris) and it is important since it provides one instance of the geodetic or true meridian. There are two methods for determining the sun azimuth; the first is known as the hour angle method and the other is called the altitude method. The hour angle method requires the determination of accurate time while altitude method requires accurate vertical angle. The hour angle method is more popular because it is more accurate, can be performed at any time of day and is applicable to the sun, Polaris and other stars. In this article, an error modeling framework for the errors result in the process of determining the sun azimuth using the hour angle method; namely random errors, is presented. A Gauss-Markov model is used to represent the errors in the true azimuth estimation process. Six sets of sun observation for azimuth data; three with telescope direct and three reverse, including horizontal circle’s readings and time were collected and used in order to estimate the true azimuth of a line in a study area in central Orlando, Florida, United States.
Compression of LiDAR Data Using Spatial Clustering and Optimal Plane-Fitting  [PDF]
Tarig A. Ali
Advances in Remote Sensing (ARS) , 2013, DOI: 10.4236/ars.2013.22008
Abstract:

With the advancement in geospatial data acquisition technology, large sizes of digital data are being collected for our world. These include air- and space-borne imagery, LiDAR data, sonar data, terrestrial laser-scanning data, etc. LiDAR sensors generate huge datasets of point of multiple returns. Because of its large size, LiDAR data has costly storage and computational requirements. In this article, a LiDAR compression method based on spatial clustering and optimal filtering is presented. The method consists of classification and spatial clustering of the study area image and creation of the optimal planes in the LiDAR dataset through first-order plane-fitting. First-order plane-fitting is equivalent to the Eigen value problem of the covariance matrix. The Eigen value of the covariance matrix represents the spatial variation along the direction of the corresponding eigenvector. The eigenvector of the minimum Eigen value is the estimated normal vector of the surface formed by the LiDAR point and its neighbors. The ratio of the minimum Eigen value and the sum of the Eigen values approximates the change of local curvature, which determines the deviation of the surface formed by a LiDAR point and its neighbors from the tangential plane formed at that neighborhood. If the minimum Eigen value is close to zero for example, then the surface consisting of the point and its neighbors is a plane. The objective of this ongoing research work is basically to develop a LiDAR compression method that can be used in the future at the data acquisition phase to help remove fake returns and redundant points.

Optimal Convergence Analysis for Convection Dominated Diffusion Problems  [PDF]
M. A. Mohamed Ali
Journal of Applied Mathematics and Physics (JAMP) , 2013, DOI: 10.4236/jamp.2013.13004
Abstract:

In classical mixed finite element method, the choice of the finite element approximating spaces is restricted by the imposition of the LBB consistency condition. The method of H1-Galerkin mixed finite element method avoids completely the imposition of such a condition on the approximating spaces. In this article, we discuss and analyze error estimates for Convection-dominated diffusion problems using H1-Galerkin mixed finite element method, along with the method of characteristics. Optimal order of convergence has been achieved for the error estimates of a two-step Euler backward difference scheme.

Partial Quality Assessment of 60Co-Teletherapy Machine Performance  [PDF]
Mohammed A. Ali Omer
Open Journal of Radiology (OJRad) , 2015, DOI: 10.4236/ojrad.2015.54032
Abstract: The aim of this study was to assess the performance of 60Co-teletherapy unit at Radiation and Isotopes Center in Khartoum, using the common tools used for quality control (Front pointer, Graphic paper, Pin, Non-screen film, meter and Check plate). The collected and analyzed data revealed that: there was a difference between the calculated theoretical field size (FS) and the measured one relative to the change of SSD; and the average FS shift was 0.9 cm relative to the standard one, while the machine isocenter was almost fixed at 0° with a shift of 0.003 cm, which was within the standard limit (0.2 cm). The diaphragm isocenter showed a shift of ±0.36 cm (i.e. in clock and anti clock wise) in average relative to standard limit (±0.3 cm) and the couch vertical isocenter (CVI) relative to the SSD changes was exceeded the standard limit (0.2 cm) by a factor of 0.9 cm. Also the SSD determined by the optical distance indicator was greater than the actual SSD (determined by Front pointer and measured by scale meter) by an average of 0.8 cm; which exceeded the limit (0.3 cm) by an average factor of 0.5 cm. The study also showed that the penumbra profile (1.5 cm) was less than the actual specified for 60Co-teletherapy machine, while the radiation beam was so homogeneous across the field size.
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