7,125 research outputs found
Soil Parameter Estimation and Analysis of Bistatic Scattering X-Band Controlled Measurements
To date only very few bistatic measurements (airborne or in controlled laboratories) have
been reported. Therefore most of the current remote sensing methods are still focused on
monostatic (backscatter) measurements. These methods, based on theoretical, empirical or
semi-empirical models, enable the estimation of soil roughness and the soil humidity
(dielectric constant). For the bistatic case only theoretical methods have been developed and
tested with monostatic data. Hence, there still remains a vital need to gain of experience and
knowledge about bistatic methods and data. The main purpose of this paper is to estimate the
soil moisture and the soil roughness by using full polarimetric bistatic measurements. In the
experimental part, bistatic X-band measurements, which have been recorded in the Bistatic
Measurement Facility (BMF) at the DLR Oberpfaffenhofen, Microwaves and Radar Institute,
will be presented. The bistatic measurement sets are composed of soils with different
statistical roughness and different moistures controlled by a TDR (Time Domain Reflectivity)
system. The BMF has been calibrated using the Isolated Antenna Calibration Technique
(IACT). The validation of the calibration was achieved by measuring the reflectivity of fresh
water. In the second part, the sensitivities of the bistatic surface scattering to soil moisture
and surface roughness will be discussed. Then, the validation of the specular algorithm by
estimating the soil moisture of two surfaces with different roughness scales will be reported.
Additionally, a new technique using the coherent term of the Integral Equation Method (IEM)
to estimate the soil roughness will be presented, as well as evaluation of the sensitivity of
phase and reflectivity with regard to moisture variation in the specular direction
Pancreatitis following Olanzapine Therapy: A Report of Three Cases
CONTEXT: Atypical antipsychotic agents (clozapine, olanzapine) have been linked to metabolic effects and acute pancreatitis. CASE REPORT: We reviewed the inpatient and outpatient records of three patients who developed acute pancreatitis while being treated with olanzapine. The mean age of the patients was 37.7 years (range 18–54 years, 2 female, 1 male). No alternative cause of acute pancreatitis was found in two of the three patients. In the remaining patient, olanzapine may have contributed to acute pancreatitis in the setting of hypertriglyceridemia. Olanzapine was discontinued in all instances. Over a mean follow-up of 14 months, one patient has had a relapsing course, but the remaining two patients have been symptom free without recurrence of acute pancreatitis. CONCLUSIONS: Our case series adds further support to the potential link between olanzapine use and acute pancreatitis. Close monitoring of metabolic parameters is suggested in patients treated with olanzapine. Alternative antipsychotic agents should be considered in patients at high risk for pancreatitis
Analysis Methods of Errors (Motion and Atmospheric) in Synthetic Aperture Radar (SAR) Images
A method to allow the analysis of the effects of motion and atmospheric errors in SAR images is here presented. The objective of the method is to allow the visualization of the effects of motion errors and atmospheric artefacts on the processed (focused) SAR image. The method is intended to allow the analysis of the interaction of motion and atmospheric errors with the adopted SAR processing procedure and motion compensation algorithms. In this article the analysis method has been applied and tested to a C-Band E-SAR (DLR airborne SAR system) data set where we see that the effects of linear and non-linear phase errors observed are in agreement with the theory
In-vehicle channel sounding in the 5.8-GHz band
The article reports vehicular channel measurements in the frequency band of 5.8 GHz for IEEE 802.11p standard. Experiments for both intra-vehicle and out-of-vehicle environments were carried out. It was observed that the large-scale variations (LSVs) of the power delay profiles (PDPs) can be best described through a two-term exponential decay model, in contrast to the linear models which are suitable for popular ultra-wideband (UWB) systems operating in the 3- to 11-GHz band. The small-scale variations (SSVs) are separated from the PDP by subtracting the LSV and characterized utilizing logistic, generalized extreme value (GEV), and normal distributions. Two sample Kolmogorov-Smirnov (K-S) tests validated that the logistic distribution is optimal for in-car, whereas the GEV distribution serves better for out-of-car measurements. For each measurement, the LSV trend was used to construct the respective channel impulse response (CIR), i.e., tap gains at different delays. Next, the CIR information is fed to an 802.11p simulation testbed to evaluate the bit error rate (BER) performance, following a Rician model. The BER results strongly vouch for the suitability of the protocol for in-car as well as out-of-car wireless applications in stationary environments.The article reports vehicular channel measurements in the frequency band of 5.8 GHz for IEEE 802.11p standard. Experiments for both intra-vehicle and out-of-vehicle environments were carried out. It was observed that the large-scale variations (LSVs) of the power delay profiles (PDPs) can be best described through a two-term exponential decay model, in contrast to the linear models which are suitable for popular ultra-wideband (UWB) systems operating in the 3- to 11-GHz band. The small-scale variations (SSVs) are separated from the PDP by subtracting the LSV and characterized utilizing logistic, generalized extreme value (GEV), and normal distributions. Two sample Kolmogorov-Smirnov (K-S) tests validated that the logistic distribution is optimal for in-car, whereas the GEV distribution serves better for out-of-car measurements. For each measurement, the LSV trend was used to construct the respective channel impulse response (CIR), i.e., tap gains at different delays. Next, the CIR information is fed to an 802.11p simulation testbed to evaluate the bit error rate (BER) performance, following a Rician model. The BER results strongly vouch for the suitability of the protocol for in-car as well as out-of-car wireless applications in stationary environments
Random forest application on cognitive level classification of E-learning content
The e-learning is the primary method of learning for most learners after the regular academics studies. The knowledge delivery through e-learning technologies increased exponentially over the years because of the advancement in internet and e-learning technologies. Knowledge delivery to some people would never have been possible without the e-learning technologies. Most of the working professional do focused studies for carrier advancement, promotion or to improve the domain knowledge. These learner can find many free e-learning web sites from the internet easily in the domain of interest. However it is quite difficult to find the best e-learning content suitable for their learning based on their domain knowledge level. User spent most of the time figuring out the right content from a plethora of available content and end up learning nothing. An intelligent framework using machine learning algorithms with Random Forest Classifier is proposed to address this issue, which classifies the e-learning content based on its difficulty levels and provide the learner the best content suitable based on the knowledge level .The frame work is trained with the data set collected from multiple popular e-learning web sites. The model is tested with real time e-learning web sites links and found that the e-contents in the web sites are recommended to the user based on its difficulty levels as beginner level, intermediate level and advanced level
Review On Laser Induced Breakdown spectroscopy: Methodology and Technical Developments
In this review we attempt to provide a brief account of laser induced
breakdown spectroscopy (LIBS) methodology and technological developments. We
also summarise various methods adopted for exploiting LIBS. Besides, a brief
overview of combination of LIBS in conjunction with other methods is also
given
Spawning behaviour and embryonic development in the sebae anemonefish Amphiprion sebae (Bleeker, 1853)
The present paper describes the spawning behaviour and embryonic development of Amphiprion sebae (Bleeker, 1853)
under captive conditions. Ten functional breeding pairs of A. sebae ranging in total length from 90 to 100 mm (female) and
60 to 80 mm (male) collected from the inshore waters of Gulf of Mannar, along with sea anemones, Stichodactyla haddoni
were acclimatised to captive conditions in 500 l glass tanks fitted with biofilter. Fishes spawned within 45 to 60 days of
rearing. Sexual dichromatism was visible in spawning pairs during the breeding season. The number of eggs in each clutch
varied between 300 to 1500 and the interval between successive spawning ranged between 15 - 26 days. The eggs were
adhesive, capsule shaped and bright orange in colour measuring 2.10±0.031 mm in length and 1.02±0.037 mm in width. The
eggs were bright orange for initial two days, turned black on 3rd to 5th day and silvery on 6th to 7th day of incubation. The
embryonic development was divided into two phases based on the morphological characteristics. The overall understanding
of spawning behaviour and embryonic development of A. sebae could help to improve the commercial production and
culture of other coral reef fishes as well
Alzheimer's disease and primary open‐angle glaucoma associated with vascular health in patients of African descent
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