351,858 research outputs found

    Farming Differentiation in the Rural-urban Interface of the Middle Mountains, Nepal: Application of Analytic Hierarchy Process (AHP)Modeling

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    This article investigates the dominant factors of farming differentiation in the rural-urban interface of the densely populated Kathmandu Valley, using the Analytic Hierarchy Process (AHP) modeling. The rural-urban interface in the Kathmandu Valley is an important vegetable production pocket which supplies a large amount of the vegetables in the city core. While subsistence farming in the rural area is characterized by a system which integrates livestock and forestry with agriculture, the intensification in the urban fringe is characterized by triple crop rotations and market-oriented intensive vegetable production. Seven factors which were supposed to cause farming variation in the interface were incorporated in the AHP framework and then subjected to the farmers’ judgment in distinctly delineated three farming zones. These factors played crucial yet differing roles in different farming zones. Inaccessibility and use of local resources; higher yield and accessibility and agro-ecological consideration and quality production are the key impacting factors of subsistence, commercial inorganic and smallholder organic farming respectively. The quantification of such factors of farming differentiation through AHP is an important piece of information that will contribute in modeling farming in the rural-urban interface of developing countries which are characterized by a high diversity of farming practices and are undergoing a rapid change in the land use pattern

    SOCIO-ECONOMIC AND ENVIRONMENTAL ASPECTS OF FARMING PRACTICES IN THE PERI-URBAN HINTERLANDS OF NEPAL

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    Spatial location of the farm households shapes farming practices and livelihoods of the farmers. Many socio-economic variables have strong spatial relations that would otherwise be missed by data aggregation at household level. Geographic Information System (GIS)provides display and analysis of socio-economic data that may be fundamental for many social scientists to understand socio-economic reality influenced by geographical position of the farm households. Present article aims at integrating socio-economic data into GIS environment to examine spatial relation in the resource availability and use employing spatial and random sampling techniques. Result demonstrates the variation in the socioeconomic attributes along the spatial gradient which is mainly related to the infrastructures such as road, market and improved agro-inputs. While households with better access to these infrastructures have tendency to use more agro-chemicals, have larger family, land holding and livestock units, better off-farm opportunities, commercial farming orientation and hence higher family income; opposite is true for the households with poor access to these infrastructures. Peri-urban farmlands, wherever agro-chemicals are applied imprudently, faces the problems of agro-ecological degradation while rural subsistence farming faces the problem of spatial poverty

    Evaluation of meteorological airborne Doppler radar

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    This paper will discuss the capabilities of airborne Doppler radar for atmospheric sciences research. The evaluation is based on airborne and ground based Doppler radar observations of convective storms. The capability of airborne Doppler radar to measure horizontal and vertical air motions is evaluated. Airborne Doppler radar is shown to be a viable tool for atmospheric sciences research

    Measurement-based analysis of delay-Doppler characteristics in an indoor environment

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    An analysis of delay-Doppler characteristics in the presence of moving people is presented for short-range communication in an indoor environment. Channel-sounding measurements have been carried out at 3.6 GHz in a crowded university hall during several short and long breaks in-between courses. During three consecutive days, the measurements were repeated with different positions for the transmit and receive antennas. In this study, the behavior of the maximum Doppler shift and the Doppler spread was analyzed in the time-delay domain as a function of the occupation of the hall, the polarizations of the 2 x 2 MIMO antennas, and their positions in the hall. The measurements reveal a clear distinction between the Doppler spread of the short and long breaks in the campaign, indicating a distinctive power distribution of their Doppler spectra. In addition, there is a significant contrast between the Doppler characteristics of the co- and cross-polarizations. Measurements at several positions reveal the importance of characterizing multipaths and show that the Doppler effect depends on the position of the antennas in the environment. In addition, this work also shows that the Doppler spectrum can be accurately modeled by a Cauchy distribution, allowing for the generation of parameters to describe Doppler characteristics

    Planetary Radio Interferometry and Doppler Experiment (PRIDE) Technique: a Test Case of the Mars Express Phobos Fly-by. 2. Doppler tracking: Formulation of observed and computed values, and noise budget

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    Context. Closed-loop Doppler data obtained by deep space tracking networks (e.g., NASA's DSN and ESA's Estrack) are routinely used for navigation and science applications. By "shadow tracking" the spacecraft signal, Earth-based radio telescopes involved in Planetary Radio Interferometry and Doppler Experiment (PRIDE) can provide open-loop Doppler tracking data when the dedicated deep space tracking facilities are operating in closed-loop mode only. Aims. We explain in detail the data processing pipeline, discuss the capabilities of the technique and its potential applications in planetary science. Methods. We provide the formulation of the observed and computed values of the Doppler data in PRIDE tracking of spacecraft, and demonstrate the quality of the results using as a test case an experiment with ESA's Mars Express spacecraft. Results. We find that the Doppler residuals and the corresponding noise budget of the open-loop Doppler detections obtained with the PRIDE stations are comparable to the closed-loop Doppler detections obtained with the dedicated deep space tracking facilities

    Sharing a common origin between the rotational and linear doppler effects

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    The well-known linear Doppler effect arises from the linear motion between source and observer, while the less well-known rotational Doppler effect arises from the rotational motion. Here, we present both theories and experiments illustrating the relationship between the rotational and linear Doppler effects. A spiral phaseplate is used to generate a light beam carrying orbital angular momentum and the frequency shift is measured arising from its rotational and/or linear motion. By considering either the motion-induced time-evolving phase or the momentum and energy conservation in light-matter interactions, we derive the rotational Doppler shift, linear Doppler shift, and overall Doppler shift associated with rotational and linear motions. We demonstrate the relationship between rotational and linear Doppler shifts, either of which can be derived from the other effect, thereby illustrating their shared origin. Moreover, the close relationship between rotational and linear Doppler effects is also deduced for a more general moving rough surface

    Measurement of particle flux in a static matrix with suppressed influence of optical properties, using low coherence interferometry

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    Perfusion measurements using conventional laser Doppler techniques are affected by the variations in tissue optical properties. Differences in absorption and scattering will induce different path lengths and consequently will alter the probability that a Doppler shift will occur. In this study, the fraction of Doppler shifted photons and the Doppler broadening of a dynamic medium, are measured with a phase modulated low coherence Mach-Zehnder interferometer. Path length-resolved dynamic light scattering measurements are performed in various media having a constant concentration of dynamic particles inside a static matrix with different scattering properties and the results are compared with a conventional laser Doppler technique, with a simple model and with Monte Carlo simulations. We demonstrate that, for larger optical path lengths, the scattering coefficient of the static matrix in which the moving particles are embedded have a small to minimal effect on the measured fraction of Doppler shifted photons and on the measured average Doppler frequency of the Doppler shifted light. This approach has potential applications in measuring perfusion independent of the influence of optical properties in the static tissue matrix

    Doppler lidar results from the San Gorgonio Pass experiments

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    During FY-84, the Doppler Lidar data from the San Gorgonio Pass experiments were analyzed, evaluated, and interpreted with regard to signal strength, signal width, magnitude and direction of velocity component and a goodness parameter associated with the expected noise level of the signal. From these parameters, a screening criteria was developed to eliminate questionable data. For the most part analysis supports the validity of Doppler Lidar data obtained at San Gorgonio Pass with respect to the mean velocity magnitude and direction. The question as to whether the Doppler width could be interpreted as a measure of the variance of the turbulence within the Doppler Lidar System (DLS) focal volume was not resolved. The stochastic nature of the Doppler broadening from finite residence time of the particles in the beam as well as other Doppler broadening phenomenon tend to mask the Doppler spread associated with small scale turbulence. Future tests with longer pulses may assist in better understanding
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