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Search Results: 1 - 10 of 480 matches for " Nima Ahmadpoor "
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A New Approach to Complex Bandpass Sigma Delta Modulator Design for GPS/Galileo Receiver  [PDF]
Nima Ahmadpoor, Ebrahim Farshidi
Circuits and Systems (CS) , 2012, DOI: 10.4236/cs.2012.31006
Abstract: In this paper, new complex band pass filter architecture for continuous time complex band pass sigma delta modulator is presented. In continuation of paper the modulator is designed for GPS and Galileo receiver. This modulator was simulated in standard 0.18 μm CMOS TSMC technology and has bandwidth of 2MHz and 4MHz for GPS and Galileo centered in 4.092 MHz. The dynamic range (DR) is 56.5/49 dB (GPS/Galileo) at sampling rate of 125 MHz. The modulator has power consumption of 4.1 mw with 3 V supply voltage.
Spatial Knowledge Acquisition in the Process of Navigation: A Review  [PDF]
Negar Ahmadpoor, Sina Shahab
Current Urban Studies (CUS) , 2019, DOI: 10.4236/cus.2019.71001
Abstract: Spatial cognition has become an increasingly important area of study since it represents a major type of human knowledge with considerable practical significance. The general assumption is that people’s spatial knowledge forms people’s spatial behaviour, such as navigation, in the environment. However, there are some critical issues within this area, including: how such knowledge is represented and organised, the mechanisms by which it is activated, and the elementary and higher-level cognitive processes that function upon the knowledge base to produce new knowledge as well as the factors that are influential on acquiring spatial knowledge. The theories regarding spatial knowledge acquisitions have attempted to address these issues. This paper discusses these issues by reviewing the literature. As such, the paper firstly provides the research background on spatial knowledge acquisition and the theories of spatial knowledge development. Secondly, the paper debates the main factors affecting acquiring and forming knowledge about the environment. In doing that, the effects of two main factors are discussed: 1) the means of spatial knowledge acquisition (direct experience, physical map, and mobile maps), and 2) the role of different properties of physical environment.
Measures and Safeguards to Realize Stable Poverty Alleviation in Contiguous Destitute Areas Based on Human Capital Development — A Case Study of Xialatuo Village  [PDF]
Garong Nima
Open Journal of Social Sciences (JSS) , 2019, DOI: 10.4236/jss.2019.74007
Abstract: Based on the perspective of human capital development, this paper explores the current situation and development of poverty alleviation in the three aspects of education, training, information resources and management organization according to the author’s research in Xialatuo Village, Luhuo County, Ganzi Tibetan Autonomous Prefecture. The precipitation and rapid development of education is the fundamental factor for the stable and stable development of the village; The advantage of information resources reduces the gap between urban and rural areas and promotes the economic development of the village; The measures and implementation of organization and management guide the development of various aspects in the village and create a lot of development conditions for farmers. Finally, the author gives some suggestions on how to stabilize poverty alleviation.
Hearing Screening Following Treatment of Neonates in NICU
Y Zahedpash,M Ahmadpoor,R Aghajani
Iranian Journal of Pediatrics , 2007,
Abstract: Background: Advances in perinatal medicine have increased the survival rate of infants admitted to neonatal intensive care unit (NICU). Many perinatal conditions may also cause hearing impairment. Early detection of hearing loss by screening and appropriate intervention are critical to speech, language and cognitive development. The aim of this study was to determine the rate of hearing damage in neonates admitted to NICU in Amirkola Childrens Hospital, Babol, Iran. Methods: This is a prospective cross-sectional, descriptive analytic study, carried out from March 2003 to April 2004. 330 neonates were screened first by Transient Evoked Otoacoustic Emissions (TEOAE) (Echocheck, Otodynamics Ltd, England), and if failed, by Auditory brainstem response (ABR) (Bera 2 Hortman Version, Beyer Dynamic Dt-48, Germany). ABR was performed with 40 db hearing level click stimulus to each ear. Data was analyzed by SPSS software using T-test and Fisher exact test. Findings: 58% of 330 NICU patients were born preterm and the rest in term. 24 neonates (7.3%) failed on TEOTE test and were referred for ABR. Before ABR testing 8 neonates died and 4 neonates had conductive hearing loss (otitis media). Finally 7 (2.1%) developed permanent hearing loss. Conclusions: Findings of this study showed that 7.3% of NICU patients failed on TEOTE and 2.1% had permanent hearing loss on ABR examination. Based on these findings, we recommend hearing screening of high risk neonates admitted to NICU.
Effect of Exchange Transfusion on ABR Abnormality Due to Severe Neonatal Hyperbilirubinemia
Y Zahedpasha,M Ahmadpoor,R Nazari
Iranian Journal of Pediatrics , 2005,
Abstract: Background: Neonatal hyperbilirubinemia, as a very common problem in neonatal period, can lead to kernicterus which is a common cause of neuro-sensory hearing loss and an avoidable cause of deafness. The aim of this study was to detect toxic effect of severe hyperbilirubinemia on brain stem and auditory tract before and after exchange transfusion (ET) by Auditory Brainstem Responses (ABR). Methods: ABR were measured in 12 full term newborns with severe hyperbilirubinemia (case) and 12 non-icteric full term neonates (control). Total bilirubin concentration in jaundiced cases was 20mg/dl and direct bilirubin 2mg/dl. ABR was performed before, 6 days and 3 months after ET. Birth weight, gestational age and age on admission were 3066 477gr, 39 1.4 weeks, and 4.25 3.1 days respectively. None of the newborns showed clinically symptoms and signs of bilirubin encephalopathy. Data are analyzed by SPSS software. Results: Two neonates did-not show ABR waves before ET, these appeared after ET. The mean latencies time of wave V of ABR before, after and at 3 months of age was 7.53 0.34, 7.43 0.33, 6.99 0.29 milliseconds (P<0.001) respectively. This showed marked improvement. The mean inter-peak –Intervals (IPI) of waves III-V were 2.58 0.19, 2.65 0.19, 2.32 0.16 respectively (P<0.009) and the IPI of waves I-V were 5.38 0.29, 6.16 0.32, 4.84 0.28 (P<0.004) respectively. This means shortening of IPI after ET. Conclusion: Our results suggest that bilirubin neurotoxicity rapidly disappears after ET. Therefore, we recommend ABR for screening and early detection of bilirubin ototoxicity for necessary audiological intervention in all cases of severe neonatal hyperbilirubinemia.
Ratio of dielectric strength of structural and secondary relaxation close to the glass transition for PPGE and DGEBA  [PDF]
Soheil Sharifi, Nima bahreini
Natural Science (NS) , 2012, DOI: 10.4236/ns.2012.47066
Abstract: Here, dielectric spectroscopy is used in the fre- quency range from 10-2 Hz up to 107 Hz and we found dynamics of the primary α-and intermolecular Johari–Goldstein β-processes are strongly correlated in diglycidyl-ether of bis-phenol-A and poly phenyl glycidyl-ether (PPGE) over a wide temperature from 193 to 345 K and pressure P range from 0.1 to 600 MPa. In contrast with the widespread opinion of statistical independence of these processes the α-β mutual dependence is quantitatively confirmed in [1] analysing the temperature and pressure behavior of the α-and (JG) β-processes the investigation of the ratio of dielectric strength of two processes close to Tg evidence that the importance of secondary dy namics in relaxing external electric stresses increase in glass formers at high pressures with respect to that of the structural relaxation. We suggest that the thermal agitation, acting above Tg is at the basis of the observed result.
Investigation of Spatial and Temporal Distribution of Snow Cover by Using Satellite Imagery (Case Study: Sheshpirdam Basin)  [PDF]
Ali Liaghat, Nima Tavanpour
Open Journal of Geology (OJG) , 2016, DOI: 10.4236/ojg.2016.65028
Abstract: About one third of the water needed for agriculture in the world is generated by melting snow. Snow cover, surface and ground water recharge are considered as sustainable and renewable resources. It is therefore necessary to identify and study these criteria. The aim of this study is to determine the spatial and temporal distribution of snow cover in the district of the Sheshpir basin in Fars province (in south of Iran). Ground-based observation of snow covers, especially in mountainous areas, is associated with many problems due to the insufficient accuracy of optical observation, as opposed to digital observation. Therefore, GIS and remote sensing technology can be partially effective in solving this problem. Images of Landsat 5TM and Landsat 7TM satellites were used to derive snow cover maps. The images in ENVI 4.8 software were classified by using the maximum likelihood algorithm. Other spatial analyses were performed in ARC-GIS 9.3 software. The maximum likelihood method was accuracy assessed by operation points of testing. The least and the average of overall accuracy of produced maps were found to be 91% and 98%, respectively. This demonstrates that the maximum likelihood method has high performance in the classification of images. Overall snow cover and the review of terrain through the years 2008-2009 and 2009-2010 showed that snow cover begins to accumulate in November and reaches its highest magnitude in February. Finally, no trace of snow can be observed on the surface of the basin in the month of May. By average, 34% of the basin is covered in snow from November through to May.
Calculate Thermal Infrared Intensity of the Hull’s Military Ship  [PDF]
Ramin Ebrahimi Laleh, Nima Ghasemloo
Journal of Geographic Information System (JGIS) , 2014, DOI: 10.4236/jgis.2014.64029

Stealth technology emphasizes on the reduction in reflection and radiation energies, the surface of target's body in the range of visual, radar, thermal and near IR and so on. Providing solutions to reduce thermal IR intensity radiation is one of the appropriate actions in passive defense for identifying power and targeting enemy. Therefore, questions are brought up: How much is the thermal IR intensity radiation of surface of the hall’s vessel? How much is the effect of each parameter? This thesis tries to provide the software to answer these questions. The provided software measures thermal IR intensity radiation of the surface of the hall’s vessel by the material substance, the temperature of the surface of the hall’s vessel, the situation and characteristic of the thermal detector, noticing the coefficient of environment atmospheric transmittal. This software by changing the effective parameters on thermal IR radiation calculates the thermal radiation on thermal detector in different situations.

Hepatoprotective Actions of Melatonin Against Methotrexate Induced Hepatic Injury in Animal Model
Eilyad Issabeagloo,Farhad Ahmadpoor,Parviz Kermanizadeh,Mohammad Taghizadiyeh
Research Journal of Biological Sciences , 2012, DOI: 10.3923/rjbsci.2011.381.385
Abstract: Methotrexate is one of the acid folic antagonists which are used widely as chemotherapy agent to treatment of kinds of leukemia and other malignancies. It has been suggested that the substance melatonin (5-methoxy-N-acetyltryptamine), discovered by Aaron Lerner in 1958, exists in almost every animal species and possibly even in all plants. In this study, 30 wistar rats were allocated into the 3 groups of 10 rats. Group 1 as control group received normal saline. Group 2 received MTX at the dose of 20 mg kg-1 as ip. Group 3 beside of MTX received melatonin at the dose of 25 mg kg-1 as oral. Results showed that AST and ALT serum levels and hepatic injury in that group received methotrexate were higher than control group and ALT serum level in that group received melatonin plus methotrexate was more than control group and was less than group 2. In this study revealed that melatonin has hepatoprotective effect against methotrexate induced hepatotoxicity in rats.
A New Integral Equation Formulation for Scattering of Electromagnetic Waves by 2D Conducting Structures, Using Cylindrical Harmonics
Nima Chamanara
PIER M , 2009, DOI: 10.2528/PIERM09042106
Abstract: Using cylindrical harmonics and Fourier series, a new integral equation formulation is derived for perfectly conducting 2D scattering problems. This new integral equation is based on the fact that, all of the electric and magnetic field components are zero inside a perfect electric conductor. The incident and scattered fields are expressed in the cylindrical coordinate system with respect to a common origin inside the scatterer, using the addition theorem for Bessel and Hankel functions. The resulting electric or magnetic field is set equal to zero for all the points inside the largest cylinder that is contained in and tangent to the surface of the scatterer. As a result the field point variables are eliminated from the integral equation and only the source points are present in this formulation. Therefore the size of the problem is reduced considerably. A dramatic improvement in the computation speed is seen compared to the classical method of moments. TE and TM scattering problems are considered and the integral equation formulation is derived and solved for both cases.
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