Analysis of Multi-Cell Downlink Cooperation with a Constrained Spatial Model

Multi-cell cooperation (MCC) mitigates intercell interference and improves throughput at the cell edge. This paper considers a cooperative downlink, whereby cell-edge mobiles are served by multiple cooperative base stations. The cooperating base stations transmit identical signals over paths with non-identical path losses, and the receiving mobile performs diversity combining. The analysis in this paper is driven by a new expression for the conditional outage probability when signals arriving over different paths are combined in the presence of noise and interference, where the conditioning is with respect to the network topology and shadowing. The channel model accounts for path loss, shadowing, and Nakagami fading, and the Nakagami fading parameters do not need to be identical for all paths. To study performance over a wide class of network topologies, a random spatial model is adopted, and performance is found by statistically characterizing the rates provided on the downlinks. To model realistic networks, the model requires a minimum separation among base stations. Having adopted a realistic model and an accurate analysis, the paper proceeds to determine performance under several resource-allocation policies and provides insight regarding how the cell edge should be defined.Comment: 6 pages, 3 figures, IEEE Global Telecommun. Conf. (GLOBECOM), 2013, to appear. arXiv admin note: text overlap with arXiv:1210.366

Identification and characterization of nursery areas of red mullet Mullus barbatus in the Central Tyrrhenian Sea

Red Mullet Mullus barbatus is an important target of fishing activities in the central Tyrrhenian Sea, so it is essential to identify its critical habitats in order to manage this resource efficiently. Our research specifically focused on the identification and characterization of nursery areas. The use of spatial interpolation techniques enabled us to identify five nurseries that were highly persistent through time. Moreover, the estimate of juvenile density confirmed the strong aggregation effect of these nursery grounds, as a great portion of young individuals were concentrated in a relatively small surface of the study area. The environmental characterization of these areas showed that juveniles were mainly distributed on bottoms with a relatively high percentage of sand (>70%; P <0.05). Shannon biodiversity index analysis indicated that the southern nurseries reached the highest values of habitat quality (P < 0.0001). Multivariate analysis showed that nursery grounds were divided into three main groups, and analysis of spatial dynamics showed that two different strategies characterized Red Mullet juveniles when density changes over time. In particular, in some areas young individuals selected habitats in a density-dependent way following the basin model scheme, while in other zones they selected habitats in a density-independent way according to the proportional density model. Results also showed that juveniles followed the proportional density model strategy into nursery areas with the highest Shannon biodiversity index values

Social costs of land use claims for transport infrastructure: a survey for The Netherlands

In this paper the social costs of land use claims for transport infrastructure are investigated for The Netherlands. This is a complement to the study on ''''Efficient pricing of traffic: estimation of the social costs of the use of transport modes" carried out in The Netherlands by CE (1999). In the present study we pay attention to the acquisition costs of land for infrastructure, the indirect costs of land use caused by infrastructure and the costs of infrastructure as barriers in - and the fragmentation of - the landscape. The paper gives an overview of the problems associated with measuring the land related costs of transport infrastructure. Estimates are given of the land use claims %28in m2) for various types of transport infrastructure. In addition some of the land related cost categories are estimated. These costs are allocated to the various transport modes (cars and trucks of various types, barges, rail and aircraft).

Regional assessment of groundwater recharge in the lower Mekong Basin

Groundwater recharge remains almost totally unknown across the Mekong River Basin, hindering the evaluation of groundwater potential for irrigation. A regional regression model was developed to map groundwater recharge across the Lower Mekong Basin where agricultural water demand is increasing, especially during the dry season. The model was calibrated with baseflow computed with the local-minimum flow separation method applied to streamflow recorded in 65 unregulated sub-catchments since 1951. Our results, in agreement with previous local studies, indicate that spatial variations in groundwater recharge are predominantly controlled by the climate (rainfall and evapotranspiration) while aquifer characteristics seem to play a secondary role at this regional scale. While this analysis suggests large scope for expanding agricultural groundwater use, the map derived from this study provides a simple way to assess the limits of groundwater-fed irrigation development. Further data measurements to capture local variations in hydrogeology will be required to refine the evaluation of recharge rates to support practical implementations

Policy issues and data communications for NASA earth observation missions until 1985

The series of LANDSAT sensors with the highest potential data rates of the missions were examined. An examination of LANDSAT imagery uses shows that relatively few require transmission of the full resolution data on a repetitive quasi real time basis. Accuracy of global crop size forecasting can possibly be improved through information derived from LANDSAT imagery. A current forecasting experiment uses the imagery for crop area estimation only, yield being derived from other data sources

Modeling of residual spheres for subduction zone earthquakes: 1. Apparent slab penetration signatures in the NW Pacific caused by deep diffuse mantle anomalies

We have computed focal residual spheres for 145 subduction zone earthquakes along the northwest edge of the Pacific using regional and global mantle velocity models from tomographic inversions. The mantle models explain much of the observed residual sphere data and, to a certain extent, suggest the location of mantle velocity heterogeneities which are responsible for various residual sphere patterns. For most deep events considered, the fast slablike residual sphere anomalies are caused by diffuse heterogeneities, mainly of deep lower mantle and receiver mantle origin rather than by an extension of the slab. The region immediately below the deepest earthquakes, depths of 650–1500 km, has an effect usually smaller than or comparable to the effect of other regions of the mantle. Without a proper account of the teleseismic effect, attributing the long-wavelength anomalies of the residual sphere to near-source slab effects alone, or even primarily, is not valid. The fast bands in many observed residual spheres agree with seismicity trends. Once the deep mantle and receiver mantle effects are removed, these may give the approximate orientation, but not the depth extent, of near-source fast velocities. For most deep earthquakes under Japan the predominant fast band is subhorizontal rather than near vertical. This type feature would be overlooked in conventional residual sphere studies using only steeply diving rays and cosine weighting of the data

Transport networks’ accessibility and jobs’ accessibility: the significance of this correlation on the configuration of labor market and their consequences on social configuration in the city Bogotá

Several researches have been done about transport in Bogotá (Colombia) but no one has treated the impact of the transport network on the configuration of employment in the city. This research has two different aims which are directly interrelated. The definition of the effective size of labor market in the city is necessary to sheds light on the relation of transport accessibility and type of jobs or social classes within different zones in Bogotá. We support the first part of our study on the existing literature about the effective size of labor market. Under the specification of a conceptual model, we want to demonstrate the significant correlation (even causality) between accessibility and type of jobs in Bogotá. In order to capture the possible endogeneity among transport' accessibility and type of jobs we will use a Structural Equation Modeling (SEM). Results will give us enough tools to know if transport network' accessibility, jobs' accessibility and type of jobs (or social classes) are large interrelated or not in the city of Bogotá. It will also let us to know if improvement of public network infrastructures traduced in a tacit enhancement on accessibility has a positive effect on incomes of inhabitants. We will understand the degree of correlation between accessibility to public transports and accessibility to jobs with respect to type of jobs and/or social class of labor force. Actually, first results show us that, there is a direct relationship between socio-economic class and time accessibility to jobs; the more accessibility of public transport system is in a zone of the city, the best is the social class and the better are the type of jobs of inhabitants so the highest will be the income. Nevertheless, it is observed (but not proved yet) that in some zones of the city where accessibility index is high, social class and types of jobs of inhabitants connected and living in these zones are not the best ones. Even so, we hope that with our methodology and data we could collect, we will be able to elucidate our research question.