Trends in the incidence of rain height and the effects on global satellite telecommunications

Satellite communications using millimetre waves, in Ka band and above, experience significant fading by rain. Strong attenuation is experienced between the ground station and a level known as the rain height, in ITU-R recommendations assumed to be 360 m above the zero-degree isotherm (ZDI). This paper examines NOAA NCEP/NCAR Reanalysis 1 data to identify changes in the ZDI height over the last 30 years. Near the equator and the poles the ZDI height has been approximately stable over this period. However, in mid-latitudes, different regions show trends of increasing or decreasing ZDI height. Over the economically important regions of North America, China and Western Europe, the ZDI height has shown an increasing trend with peak rates in the range of 8 to 10 metres per year. Given a twenty-year life-time of a satellite system, this could lead to a 10 to 20% increase in fade intensity from a similar rain event. The effect will be compounded by increasing trends in the incidence of heavy rain recently identified in UK data. These trends will need to be considered when designing new systems

A rain height model to predict fading due to wet snow on terrestrial links

Recommendation ITU‐R P.530‐13 provides an internationally recognized prediction model for the fading due to wet snow on low‐elevation, terrestrial microwave links. An important parameter in this model is the altitude difference between the link and the rain height. The top of rain events is usually assumed to be 360 m above the zero‐degreeisotherm (ZDI). Above this height, hydrometeors are ice with low specific attenuation. Below this level, melting ice particles produce a specific attenuation up to 4 times that of the associated rain rate. A previous paper identified increasing ZDI height trends across northern Europe, North America and central Asia with slopes up to 10 m/yr. This paper examines NOAA National Centers for Environmental Prediction-National Center for Atmospheric Research Reanalysis 1 data to identify global distributions of ZDI height around mean levels that increase linearly over time. The average annual distribution of ZDI heights relative to the annual mean are calculated for each NOAA Reanalysis grid square and skew normal distributions are fitted. These are compared to models in Recommendation ITU‐R P.530‐13 and Recommendation ITU‐R 452‐14. The effects of ZDI trends and the calculated skew normal distributions are illustrated using calculated trends in fading due to wet snow for two notional 38 GHz links in Edinburgh. A slow decrease in the incidence of fading due to wet snow is predicted over most of Europe. However, some links could experience increases where warming has increased the wetness of snow

Innovative Approach for Heating of Buildings Using Water from a Flooded Coal Mine Through an Open Loop Based Single Shaft GSHP System

Geothermal energy, deep and shallow, has always been identified as an important renewable energy resource. The stable temperature and relatively low enthalpy of mine water contained in the abandoned and flooded coal mines have the potential to form a geothermal resource to be used in conjunction with heat pumps to provide heating and cooling for buildings. The usage of heat pump for space heating and cooling can be classified as a low carbon technology and if heat pump is powered by solar or wind energy it can be classified as a truly renewable technology. This paper presents a novel application of Ground Source Heat Pump (GSHP) for space heating and cooling using a flooded coal mine through an open loop based single shaft system. In this novel application, a single shaft is used for both extraction and injection of mine water for the heating application. This research work will report on the performance of the system and its long term potential in comparison to standard gas boilers heating systems. The usage of a single shaft system has been found effective in developing an efficient heating system with reduced cost and neutral environmental impact

Modified GR and Helium Nucleosynthesis

We show that a previously proposed cosmological model based on general relativity with non vanishing divergence for the energy-momentum tensor is consistent with the observed values for the nucleosynthesis of helium for some values of the arbitrary parameter $\alpha$ presented in this model. Further more values of $\alpha$ can be accommodated if we adopt the Randall-Sundrum single brane model.Comment: 5 page

Challenges and influential factors in ERP adoption and implementation

The adoption and implementation of Enterprise Resource Planning (ERP) systems is a challenging and expensive task that not only requires rigorous efforts but also demands to have a detailed analysis of such factors that are critical to the adoption or implementation of ERP systems. Many efforts have been made to identify such influential factors for ERP; however, they are not filtered comprehensively in terms of the different perspectives. This paper focuses on the ERP critical success factors from five different perspectives such as: stakeholders; process; technology; organisation; and project. Results from the literature review are presented and 19 such factors are identified that are imperative for a successful ERP implementation, which are listed in order of their importance. Considering these factors can realize several benefits such as reducing costs and saving time or extra effort

Cities as emergent models: the morphological logic of Manhattan and Barcelona

This paper is set to unveil several particulars about the logic embedded in the diachronic model of city growth and the rules which govern the emergence of urban spaces. The paper outlines an attempt to detect and define the generative rules of a growing urban structure by means of evaluation techniques. The initial approach in this regards will be to study the evolution of existing urban regions or cities which in our case are Manhattan and Barcelona and investigate the rules and causes of their emergence and growth. The paper will concentrate on the spatial aspect of the generative rules and investigate their behaviour and dimensionality. Several Space Syntax evaluation methods will be implemented to capture the change of spatial configurations within the growing urban structures. In addition, certain spatial elements will be isolated and tested aiming to illustrate their influence on the main spatial structures. Both urban regions were found to be emergent products of a bottom up organic growth mostly distinguished in the vicinities of the first settlements. Despite the imposition of a uniform grid on both cities in later stages of their development these cities managed to deform the regularity in the preplanned grid in an emergent manner to end up with an efficient model embodied in their current spatial arrangement. The paper reveals several consistencies in the spatial morphology of both urban regions and provides explanation of these regularities in an approach to extract the underlying rules which contributed to the growth optimization process

Evaluating m-government applications: an elaboration likelihood model framework

Mobile government application and services refer to governmental functions that are available to mobile devices, such as smart phones or personal digital assistants, to the users anytime/anywhere. M-Government and m-Participation are emergent concepts used to represent the evolving field of public administration functions provided as mobile services and the provision of participation to public consultations via mobile devices accordingly. In this paper we present an evaluation framework for m-government tools. The evaluation approach is grounded on the assumption that m-government tools should not only provide access to governmental information and functions, but they should also motivate users to participate to public policy making processes. The evaluation approach is based on the Elaboration Likelihood Model. Its novelty lies on a) its ability to capture the actual performance of a system instead of the users’ perceptions, and b) its capacity to assess the motivational and persuasive ability of a system.EU FP7 Marie Curie People Project “CEES - Citizen oriented Evaluation of E-Government Systems (reference IAPP-2008-230658) and EU FP7 Project “UbiPOL- Ubiquitous Participation Platform for Policy Making” (Reference INFSO-ICT-248010)

On two-dimensional quantum gravity and quasiclassical integrable hierarchies

The main results for the two-dimensional quantum gravity, conjectured from the matrix model or integrable approach, are presented in the form to be compared with the world-sheet or Liouville approach. In spherical limit the integrable side for minimal string theories is completely formulated using simple manipulations with two polynomials, based on residue formulas from quasiclassical hierarchies. Explicit computations for particular models are performed and certain delicate issues of nontrivial relations among them are discussed. They concern the connections between different theories, obtained as expansions of basically the same stringy solution to dispersionless KP hierarchy in different backgrounds, characterized by nonvanishing background values of different times, being the simplest known example of change of the quantum numbers of physical observables, when moving to a different point in the moduli space of the theory.Comment: 20 pages, based on talk presented at the conference "Liouville field theory and statistical models", dedicated to the memory of Alexei Zamolodchikov, Moscow, June 200

A hybrid GA–PS–SQP method to solve power system valve-point economic dispatch problems

This study presents a new approach based on a hybrid algorithm consisting of Genetic Algorithm (GA), Pattern Search (PS) and Sequential Quadratic Programming (SQP) techniques to solve the well-known power system Economic dispatch problem (ED). GA is the main optimizer of the algorithm, whereas PS and SQP are used to fine tune the results of GA to increase confidence in the solution. For illustrative purposes, the algorithm has been applied to various test systems to assess its effectiveness. Furthermore, convergence characteristics and robustness of the proposed method have been explored through comparison with results reported in literature. The outcome is very encouraging and suggests that the hybrid GA–PS–SQP algorithm is very efficient in solving power system economic dispatch problem