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匹配条件： “Subash Vegesna;Mohammad A. Saed” ，找到相关结果约568093条。
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Novel Compact Dual-Band Bandpass Microstrip Filter
Subash Vegesna;Mohammad A. Saed
PIER B , 2010, DOI: 10.2528/PIERB10012210

Abstract: In this paper, a novel microstrip structure is developed to realize a dual-band bandpass filter. The proposed bandpass structure uses a microstrip resonator with two independently controlled resonance frequencies producing two frequency bands of interest controlled by adjusting the dimensions of the resonator. Parametric analysis is performed on the structure to determine the optimum dimensions to obtain the desired frequency response and is explained in the paper. The dual-band bandpass filter developed in this paper exhibits dual operating frequencies at 1390 MHz and 2520 MHz with 9.85% and 9.92% fractional bandwidths respectively. We achieved a compact second-order dual-band bandpass filter with controllable resonance frequencies and low insertion losses in the passband with high selectivity. The measured results are in good agreement with simulated results. Additionally, it can be easily fabricated and can be used in applications where miniaturization and compatibility with microstrip technology are of primary concern.

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Compact Two-Layer Microstrip Bandpass Filters Using Broadside-Coupled Resonators
Subash Vegesna;Mohammad A. Saed
PIER B , 2012, DOI: 10.2528/PIERB11101708

Abstract: This paper presents a design methodology for realizing broadside-coupled microstrip bandpass filters on multilayer substrates to reduce the size of the filter. The new filter configuration consists of broadside coupled split-ring resonators on two layers backed by a ground plane. With the proposed new method, miniaturization to a greater extent can be achieved compared to the conventional method of realizing microstrip multilayer filters. In addition, coupling apertures in the ground plane used to achieve coupling among the resonators in conventional multilayer structures are eliminated. The proposed design is more flexible compared to traditional multilayer filters. Layers can be easily added to increase the filter order. To demonstrate the method, a miniaturized two-layered bandpass filter centered at 728 MHz with low insertion loss is implemented and investigated. Miniaturization of more than 25% is achieved compared to the conventional broadside coupled structure and more than 40% miniaturization compared to the edge coupled structure. The new microstrip filter discussed in this paper can be realized using simple fabrication techniques.

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Broadband CPW-FED Planar Slot Antennas with Various Tuning Stubs
Mohammad A. Saed
PIER , 2006, DOI: 10.2528/PIER06112703

Abstract: This paper investigates broadband planar antennas that consist of a wide rectangular slot with various tuning stubs. The antennas are fed by coplanar waveguides. Wide slots containing a single tuning stub, V-shaped stubs, as well as inverted F-shaped stubs are investigated. Despite using a high dielectric constant substrate, the proposed antennas exhibit very broad bandwidth. They also have broadside bidirectional radiation. The radiation pattern stability with frequency for the various configurations is presented. One of the proposed configurations, the inverted F stub in a wide rectangular slot, produced very stable radiation patterns over its entire impedance bandwidth of about 40%. Also, an impedance bandwidth of 44% was obtained for the V-shaped stub in a rectangular slot. Simulations as well as experimental results are presented.

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Microstrip - FED Low Profile and Compact Dielectric Resonator Antennas
Mohammad A. Saed;Rohini Yadla
PIER , 2006, DOI: 10.2528/PIER05041401

Abstract: This paper presents a novel broadband, low-profile dielectric resonator antenna using relatively low dielectric constant substrate material. The rectangular DRA is fed with a stepped microstrip feed to ensure efficient coupling. Bandwidths in excess of 17% are obtained. In addition, the paper investigates methods to miniaturize the antenna using metallic strips or patches. Substantial size reduction is demonstrated while maintaining a reasonable bandwidth. Simulations as well as experimental results are presented.

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Tunable Filtenna Using Varactor Tuned Rings FED with an Ultra Wideband Antenna
Jason Leo Durbin;Mohammad A. Saed
PIER Letters , 2012, DOI: 10.2528/PIERL11111810

Abstract: A tunable filtering antenna (filtenna) realized using rings fed with an ultra-wideband (UWB) planar, elliptical monopole antenna is proposed. An array of slotted rings with varactors is placed in close proximity of the planar monopole to obtain the low profile tunable filtenna. The array of rings can be viewed as a small tunable frequency selective surface. The design produces a tuning range of about 3.8-4.4 GHz over a varactor reverse bias voltage of 1-4 V.

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Fourier Transform Infrared Spectroscopy Typing an Enterococcus sp. [PDF]
Mohammad I. Abu Taha, Hatem K. Eideh, Sameeh M. Saed, Hazem Jaber
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.516169

Abstract: Enterococcus species are one of the leading causes of nosocomial infections, which are difficult to treat specially with the rise of its Vancomycin resistant. Studies of Enterococcus isolates are essential for epidemiological investigation. Typing Enterococci is often based on the traditional phenotypic as well as genotypic methods. In this study Fourier-transform infrared (FTIR) spectroscopy is used as a novel phenotypic approach to the typing of Enterococci. FTIR spectroscopy results compared to antibiotic susceptibility testing and PCR amplification of Vancomycin gene results; the analysis showed that, 6 isolates were positive for Van gene (4 of VanA, 1 of VanB and 1 VanA plus VanB). Three of VanA and VanA plus VanB were resistant to all antibiotic tested (Ampicillin, Teicoplamin and Vancomycin) and VanB was found to be sensitive. FTIR spectroscopy (first derivatives) divided the isolates into 8 groups. 3 groups of VanA (4 isolates), one of VanB (one isolate), one of VanA plus VanB (one isolate) and the other 13 Enterococcus isolates were divided into 3 clusters. The study demonstrated that FTIR spectroscopy has good discriminative capacity and high reproducibility as compared to other techniques.

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Risk Factors Associated with Various Subtypes of Ischemic Stroke: A Prospective Study in BSMMU, Dhaka, Bangladesh [PDF]
Mohammad Shahidullah, Nahid Sultana, Subash Kanti Dey, Anis Ahmed, Shukur Ali, Md. Raknuzzaman
Neuroscience & Medicine (NM) , 2021, DOI: 10.4236/nm.2021.124010

Abstract: Introduction: Stroke is the main cause of adult disability and the second most leading cause of death worldwide. The number of deaths due to stroke is 5.54 million worldwide. Globally, 70% of strokes and 87% of both stroke-related deaths and disability-adjusted life years occur in low and middle-income countries. Method: This was a prospective observational cross-sectional study conducted at Indoor, Outdoor, Stroke and Neuro-Intervention clinic of the Department of Neurology, Bangabandhu Sheikh Mujib Medical University Hospital (BSMMU), Dhaka, Bangladesh, from June-2019 to May-2020. A total of 220 ischemic stroke patients aged above 30 years confirmed by CT scan/MRI of brain. Data were collected with a pre-structured questionnaire from the patients, investigations reports and face-to-face interviews and analyzed using IBM SPSS software version 23.0. Proper consent was taken from the participants. The collected data were ANNOVA tests and association within the risk factors and the patterns of subtypes of ischemic stroke where P < 0.05 considered significant. Results: Among the 220 stroke patients, large-artery atherosclerosis (LAA), cardio-embolism (CE), small-vessel occlusion (SVO, stroke of other determined etiology (SODE) and stroke of undetermined etiology (SUDE) were being observed 84 (38.18%), 14 (6.36%), 63 (28.64%), 12 (5.45%) and 47 (18.18%). Eighty-Six (39.09%) prevalence of subtypes was found in rural areas whereas 134 (60.91%) were in urban areas. The significant risk factors are associated with the prevalence of various subtypes (p < 0.05). Conclusion: This study prevails the people of Bangladesh are vulnerable to various subtypes of ischemic stroke. The higher prevalence of large-artery atherosclerosis (LAA) in our patients suggests the presence of uncontrolled hypertension, diabetes mellitus, smoking habit and dyslipidemia.

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Comparing Relationships among Yield and Its Related Traits in Mycorrhizal and Nonmycorrhizal Inoculated Wheat Cultivars under Different Water Regimes Using Multivariate Statistics
Armin Saed-Moucheshi,Mohammad Pessarakli,Bahram Heidari
International Journal of Agronomy , 2013, DOI: 10.1155/2013/682781

Abstract:

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Abstract: Multivariate statistical techniques were used to compare the relationship between yield and its related traits under noninoculated and inoculated cultivars with mycorrhizal fungus (Glomus intraradices); each one consisted of three wheat cultivars and four water regimes. Results showed that, under inoculation conditions, spike weight per plant and total chlorophyll content of the flag leaf were the most important variables contributing to wheat grain yield variation, while, under noninoculated condition, in addition to two mentioned traits, grain weight per spike and leaf area were also important variables accounting for wheat grain yield variation. Therefore, spike weight per plant and chlorophyll content of flag leaf can be used as selection criteria in breeding programs for both inoculated and noninoculated wheat cultivars under different water regimes, and also grain weight per spike and leaf area can be considered for noninoculated condition. Furthermore, inoculation of wheat cultivars showed higher value in the most measured traits, and the results indicated that inoculation treatment could change the relationship among morphological traits of wheat cultivars under drought stress. Also, it seems that the results of stepwise regression as a selecting method together with principal component and factor analysis are stronger methods to be applied in breeding programs for screening important traits. 1. Introduction Bread wheat (Triticum aestivum L.) is one of the most widely cultivated and important food crop in the world. Development of high yielding wheat cultivars is the major objective of breeding programs [1]. On the other hand, targeted efforts to breed genotypes for improved mycorrhizal symbiosis result in increased yield in crops under a wide range of environmental conditions and contribute toward sustainability of agricultural ecosystems in which soil-plant-microbe interactions will be better exploited. Screening genotypes via molecular biology and traditional breeding techniques can increase productivity of symbioses and eventually result in increased economic yield of crop plants [2]. Arbuscular mycorrhizal (AM) fungi colonize the roots of most monocotyledons and dicotyledons, including important crops such as rice, maize, and wheat despite their different root architecture and cell patterning. In nature, mineral nutrient acquisition and water uptake by plant roots are often assisted by symbioses with beneficial AM fungi. During this intimate association, the extraradical hyphal mycelium acquires minerals from the soil beyond the zone

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Empirical Formalism for the Phantom Scatter Factor of Small Fields: Using Different Density Media [PDF]
Saed J. Al Atawneh
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2022, DOI: 10.4236/ijmpcero.2022.111004

Abstract: We present the Empirical Formula (EF) to calculate the phantom scatter factor, S_p, of small radiation fields under charge particle dis-equilibrium conditions. The Empirical Formula (EF) was verified by examining the calculated data with experimentally measured data utilizing the anthropomorphic phantom in twelve different combinations of beam entry and point location, where the value for S_p per tissue composition was within 3% in 8/12 cases, 5% in 1/12 cases, and 10% in 3/12 cases. Our results showed a good agreement with experimental data to less than 1% when the ion chamber was surrounded by the homogeneous tissue, whether lung, soft tissue, or bone. Indicating that the prediction of the equation is valid, and it can be reliably used for phantom scatter factor calculation for different homogeneous media under charge particle dis- equilibrium conditions.

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