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Search Results: 1 - 10 of 150284 matches for " Yahya H. Almohmeed "
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Systematic Review and Meta-Analysis of the Sero-Epidemiological Association between Epstein Barr Virus and Multiple Sclerosis
Yahya H. Almohmeed, Alison Avenell, Lorna Aucott, Mark A Vickers
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061110
Abstract: Background A role for Epstein Barr virus (EBV) in multiple sclerosis (MS) has been postulated. Previous systematic reviews found higher prevalences of anti-EBV antibodies in MS patients compared to controls, but many studies have since been published, and there is a need to apply more rigorous systematic review methods. Methodology/Principal Findings We examined the link between EBV and MS by conducting a systematic review and meta-analysis of case-control and cohort studies that examined the prevalence of anti-EBV antibodies in the serum of cases and controls. We searched Medline and Embase databases from 1960 to 2012, with no language restriction. The Mantel-Haenszel odds ratios (OR) for anti-EBV antibodies sero-positivity were calculated, and meta-analysis conducted. Quality assessment was performed using a modified version of the Newcastle Ottawa scale. Thirty-nine studies were included. Quality assessment found most studies reported acceptable selection and comparability of cases and controls. However the majority had poor reporting of ascertainment of exposure. Most studies found a higher sero-prevalence of anti-EBNA IgG and anti-VCA IgG in cases compared to controls. The results for anti-EA IgG were mixed with only half the studies finding a higher sero-prevalence in cases. The meta-analysis showed a significant OR for sero-positivity to anti-EBNA IgG and anti-VCA IgG in MS cases (4.5 [95% confidence interval (CI) 3.3 to 6.6, p<0.00001] and 4.5 [95% CI 2.8 to 7.2, p<0.00001] respectively). However, funnel plot examination suggested publication bias for the reporting of the anti-EBNA IgG. No significant difference in the OR for sero-positivity to anti-EA IgG was found (1.4 [95% CI 0.9 to 2.1, p = 0.09]). Conclusion/Significance These findings support previous systematic reviews, however publication bias cannot be excluded. The methodological conduct of studies could be improved, particularly with regard to reporting and conduct of laboratory analyses.
Increasing Microstrip Patch Antenna Bandwidth by Inserting Ground Slots  [PDF]
Yahya S. H. Khraisat
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2018, DOI: 10.4236/jemaa.2018.101001
Abstract: Microstrip patch antenna (MPA) is widely implemented in different communication systems. One of the main disadvantages of MPA which limits its applications is its narrow bandwidth. In this paper I enhanced the bandwidth of MPA by inserting multiple slots in its ground plane. I used FR-4 substrate to design this antenna. The dimensions of this antenna are 59 mm and 79 mm. The dielectric constant is 4.4 and the height is 1.6 mm. I inserted up to 15 slots in ground plane with 1mm width. The spacing between slots is 3 mm. I investigated two designs. In the first design, slots were arranged in parallel to the feeding line. In the second one, slots were arranged horizontally to the feeding line. The main objective of this paper is to design and simulate MPA suitable for wide number of applications. Antenna bandwidth improvement is 18%. All the simulations were obtained by using HFSS simulator.
Identification Schemes for Unmanned Excavator Arm Parameters

Yahya H Zweiri,

国际自动化与计算杂志 , 2008,
Abstract: Parameter identification is a key requirement in the field of automated control of unmanned excavators (UEs). Furthermore, the UE operates in unstructured, often hazardous environments, and requires a robust parameter identification scheme for field applications. This paper presents the results of a research study on parameter identification for UE. Three identification methods, the Newton-Raphson method, the generalized Newton method, and the least squares method are used and compared for prediction accuracy, robustness to noise and computational speed. The techniques are used to identify the link parameters (mass, inertia, and length) and friction coefficients of the full-scale UE. Using experimental data from a full-scale field UE, the values of link parameters and the friction coefficient are identified. Some of the identified parameters are compared with measured physical values. Furthermore, the joint torques and positions computed by the proposed model using the identified parameters are validated against measured data. The comparison shows that both the Newton-Raphson method and the generalized Newton method are better in terms of prediction accuracy. The Newton-Raphson method is computationally efficient and has potential for real time application, but the generalized Newton method is slightly more robust to measurement noise. The experimental data were obtained in collaboration with QinetiQ Ltd.
Design of 4 Elements Rectangular Microstrip Patch Antenna with High Gain for 2.4 GHz applications
Yahya S. H. khraisat
Modern Applied Science , 2011, DOI: 10.5539/mas.v6n1p68
Abstract: In the recent years the development in communication systems requires the development of low cost, minimal weight and low profile antennas that are capable of maintaining high performance over a wide spectrum of frequencies. This technological trend has focused much effort into the design of a microstrip patch antenna. The objective of this paper is to design, and fabricate an inset fed rectangular microstrip patch antenna. Therefore, a novel particle swarm optimization method based on IE3D was used to design an inset feed linearly polarized rectangular microstrip patch antenna with four element array. The length of the antenna is nearly half wavelength in the dielectric; it’s a very critical parameter, which governs the resonant frequency of the antenna. In view of design, selection of the patch width and length are the major parameters along with the feed line depth. Desired patch antenna design was simulated by IE3D simulator program. Initially we set our antenna as a single patch and after evaluating the outcomes of antenna features, operation frequency, radiation patterns, reflected loss, efficiency and antenna gain, and then we transformed it to a 2x1 linear array. Then we analyzed the 4x1 linear antenna array to increase directivity, gain, efficiency, and have better radiation patterns.
Simulation the Hybrid Combinations of 24GHz and 77GHz Automotive Radar
Yahya S. H. Khraisat
Applied Physics Research , 2012, DOI: 10.5539/apr.v4n1p193
Abstract: In this paper we used MATLAB simulation to simulate the hybrid combinations of short range automotive radar (SRR) operating at frequency 24 GHz and long range automotive radar (LRR) operating at frequency 77 GHz. We obtained the velocity, the range and the time of scanning target. The objective of this work is to get the advantage of both SRR and LRR covering short and long distance with high resolution from 1m to 200m range.
Analysis of the Parameters of Symmetrical Multi – Fed Full – Wave Dipole Antenna
Yahya S. H. Khraisat
Computer and Information Science , 2012, DOI: 10.5539/cis.v5n2p69
Abstract: This paper demonstrates the analysis of the parameters of symmetrical full-wave dipole antenna based on multi – fed techniques. The current distributions were measured, followed by the measurement of parameters of antenna like gain, radiation patterns and input impedance. Based on these observations four equations for current distribution were eventually formulated. These equations were then used to compute the values of the same parameters of the antenna. Finally, the values of parameters obtained practically and theoretically were compared to analyse the validity of the developed equation.
Design a Wireless Meteorological Station in Jordan
Yahya S. H. Khraisat
Computer and Information Science , 2011, DOI: 10.5539/cis.v5n1p87
Abstract: This paper demonstrates a low-cost, yet reliable, weather monitoring system. The proposed system has three sensors that measure the temperature, wind speed and wind direction, respectively. The analogue outputs of the sensors converted to digital signals and further processed by a microcontroller. Using easily-available components and simple circuitry, the system should be beneficial in providing a portable and low-cost weather monitoring using wireless communication system. Until now these parameters in the meteorological department in Jordan are transmitted by telephone. In this system we developed an automated system which continuously measures weather parameter and transmit them to the main meteorological station. In future we are planning to have more substations which can interact with main station.
Design of Integrated Triple Band Notched for Ultra-Wide Band Microstrip Antenna  [PDF]
Yahya S. H. Khraisat, Ahmad Bataineh, Malak Angor
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2015, DOI: 10.4236/jemaa.2015.73011
Abstract: Ultra-wideband (UWB) is one of the recent topics that received a great concern from academia and industry. However, UWB found many difficulties to be standardized due to the overlay working that made UWB an important potential interference source to many licensed and unlicensed spectrum throughout the band 3.1 to 10.6 GHz. This paper demonstrates the design of integrated triple band notched for UWB Microstrip antenna. We simulated UWB short range systems which require low power and these are built using inexpensive digital components. We proposed a compact triple band notched CPW (Co-planar Waveguide) fed Micro strip Antenna (MSA) for UWB. This band-notched antenna has rejection characteristics at 3.2 GHz (for Wi-MAX band 3.16 to 3.32 GHz), at 5.5 GHz (for WLAN 2 band—5.3 to 5.72 GHz) and at 7.9 GHz (for ITU band 7.72 GHz to 8.13 GHz). The simulation was done using IE3D simulator.
Fuzzy-Weighted Similarity Measures for Memory-Based Collaborative Recommender Systems  [PDF]
Mohammad Yahya H. Al-Shamri, Nagi H. Al-Ashwal
Journal of Intelligent Learning Systems and Applications (JILSA) , 2014, DOI: 10.4236/jilsa.2014.61001
Abstract:

Memory-based collaborative recommender system (CRS) computes the similarity between users based on their declared ratings. However, not all ratings are of the same importance to the user. The set of ratings each user weights highly differs from user to user according to his mood and taste. This is usually reflected in the user’s rating scale. Accordingly, many efforts have been done to introduce weights to the similarity measures of CRSs. This paper proposes fuzzy weightings for the most common similarity measures for memory-based CRSs. Fuzzy weighting can be considered as a learning mechanism for capturing the preferences of users for ratings. Comparing with genetic algorithm learning, fuzzy weighting is fast, effective and does not require any more space. Moreover, fuzzy weightings based on the rating deviations from the user’s mean of ratings take into account the different rating scales of different users. The experimental results show that fuzzy weightings obviously improve the CRSs performance to a good extent.

Morphometric Assessment of Wadi Wala Watershed, Southern Jordan Using ASTER (DEM) and GIS  [PDF]
Yahya Farhan
Journal of Geographic Information System (JGIS) , 2017, DOI: 10.4236/jgis.2017.92011
Abstract: Morphometric analysis is of vital concern to understand hydromophological processes in a given watershed, and thus, it is a priority for assessing water resources in drainage basins. A morphometric analysis was conducted to identify the drainage properties of Wadi Wala and the 23 fourth-order sub-basins. ASTER DEM data was employed to compile slope, elevation, and aspect maps. Arc GIS software was used to measure and calculate basic, derived and shape morphometric parameters. W. Wala is found to be a sixth-order drainage basin, and the drainage pattern is trellis to sub-trellis in the central and lower part of the catchment, whereas it is dendritic to sub-dendritic pattern in the southern and northern parts. The slopes of the catchment vary from 0° - 5° to >35° in slope categories. Tectonic uplifting and tilting, lithology, structure and rejuvenation are the major factors controlling morphological variation over the watershed. The recognized fault systems are chiefly controlling the drainage pattern, and the elongated shape of the sub-basins is attributed to dense lineaments in the central and eastern parts of the watershed. The Rb values for the entire catchment and the sub-catchments range from 2 to 7, with a mean of 4.55, which indicates the distortion of drainage pattern by geological structure. Hypsometric integral values are high for the W. Wala watershed and the sub-basins, where it ranges from 70% to 89%. High HI values indicate that drainage basins are at the youth-age stage of geomorphic development, and they are affected by tectonic uplifting, tilting, and the dominance of hillslope process. Variation in HI values is apparent between sub-basins located at the western part, or, the rejuvenated belt where HI values range from 85% to 89%. Whereas the HI values of the sub-basins located at the eastern part of the watershed, vary from 70% to 84%. Regression analysis reveals that R2 values, which represent the degree of control of driving parameters on HI are reasonably high for the height of local base level (m) and the mean height of sub-basins (m). Both parameters contribute 0.42 and 0.39 respectively (where the F-value is significant at 0.1% and 0.5% levels). Such results imply that the height of local base level (m), and the mean height (m) are the only morphometric driving parameters which have significant control on HI values in the W. Wala watershed. High annual soil loss and sediment load estimated recently, denote that the catchment is highly susceptible to surface erosion at present. Hence, the present study, and
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