750 research outputs found
An assessment of NASA master directory/catalog interoperability for interdisciplinary study of the global water cycle
The most important issue facing science is understanding global change; the causes, the processes involved and their consequences. The key to success in this massive Earth science research effort will depend on efficient identification and access to the most data available across the atmospheric, oceanographic, and land sciences. Current mechanisms used by earth scientists for accessing these data fall far short of meeting this need. Scientists must as a result frequently rely on a priori knowledge and informal person to person networks to find relevant data. The Master Directory/Catalog Interoperability Program (MC/CI) undertaken by NASA is an important step in overcoming these problems. The stated goal of the MD project is to enable researchers to efficiently identify, locate, and obtain access to space and Earth science data
Properties and performance of the prototype instrument for the Pierre Auger Observatory
Construction of the first stage of the Pierre Auger Observatory has begun. The aim of the Observatory is to collect unprecedented information about cosmic rays above 10^18 eV. The first phase of the project, the construction and operation of a prototype system, known as the engineering array, has now been completed. It has allowed all of the sub-systems that will be used in the full instrument to be tested under field conditions. In this paper, the properties and performance of these sub-systems are described and their success illustrated with descriptions of some of the events recorded thus far.Facultad de Ciencias Exacta
Properties and performance of the prototype instrument for the Pierre Auger Observatory
Construction of the first stage of the Pierre Auger Observatory has begun. The aim of the Observatory is to collect unprecedented information about cosmic rays above 10^18 eV. The first phase of the project, the construction and operation of a prototype system, known as the engineering array, has now been completed. It has allowed all of the sub-systems that will be used in the full instrument to be tested under field conditions. In this paper, the properties and performance of these sub-systems are described and their success illustrated with descriptions of some of the events recorded thus far.Facultad de Ciencias Exacta
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The Surface Detector System of the Pierre Auger Observatory
The Pierre Auger Observatory is designed to study cosmic rays with energies greater than 10{sup 19} eV. Two sites are envisaged for the observatory, one in each hemisphere, for complete sky coverage. The southern site of the Auger Observatory, now approaching completion in Mendoza, Argentina, features an array of 1600 water-Cherenkov surface detector stations covering 3000 km{sup 2}, together with 24 fluorescence telescopes to record the air shower cascades produced by these particles. The two complementary detector techniques together with the large collecting area form a powerful instrument for these studies. Although construction is not yet complete, the Auger Observatory has been taking data stably since January 2004 and the first physics results are being published. In this paper we describe the design features and technical characteristics of the surface detector stations of the Pierre Auger Observatory
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Precise positioning in real-time using GPS-RTK signal for visually impaired people navigation system
This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University, 24/9/2010.This thesis presents the research carried out to investigate and achieve highly reliable and accurate navigation system of guidance for visually impaired pedestrians. The main aim with this PhD project has been to identify the limits and insufficiencies in utilising Network Real-Time Kinematic Global Navigation Satellite Systems (NRTK GNSS) and its augmentation techniques within the frame of pedestrian applications in a variety of environments and circumstances. Moreover, the system can be used in many other applications, including unmanned vehicles, military applications, police, etc. NRTK GNSS positioning is considered to be a superior solution in comparison to the conventional standalone Global Positioning System (GPS) technique whose accuracy is highly affected by the distance dependent errors such as satellite orbital and atmospheric biases.
Nevertheless, NRTK GNSS positioning is particularly constrained by wireless data link coverage, delays of correction and transmission and completeness, GPS and GLONASS signal availability, etc., which could downgrade the positioning quality of the NRTK results.
This research is based on the dual frequency NRTK GNSS (GPS and GLONASS). Additionally, it is incorporated into several positioning and communication methods responsible for data correction while providing the position solutions, in which all identified contextual factors and application requirements are accounted.
The positioning model operates through client-server based architecture consisted of a Navigation Service Centre (NSC) and a Mobile Navigation Unit (MNU). Hybrid functional approaches were consisting of several processing procedures allowing the positioning model to operate in position determination modes. NRTK GNSS and augmentation service is used if enough navigation information was available at the MNU using its local positioning device (GPS/GLONASS receiver).The positioning model at MNU was experimentally evaluated and centimetric accuracy was generally attained during both static and kinematic tests in various environments (urban, suburban and rural). This high accuracy was merely affected by some level of unavailability mainly caused by GPS and GLONASS signal blockage. Additionally, the influence of the number of satellites in view, dilution of precision (DOP) and age corrections (AoC) over the accuracy and stability of the NRTK GNSS solution was also investigated during this research and presented in the thesis.
This positioning performance has outperformed the existing GPS service. In addition, utilising a simulation evaluation facility the positioning model at MNU performance was quantified with reference to a hybrid positioning service that will be offered by future Galileo Open Service (OS) along with GPS. However, a significant difference in terms of the service availability for the advantage of the hybrid system was experienced in all remaining scenarios and environments more especially the urban areas due to surrounding obstacles and conditions.
As an outcome of this research a new and precise positioning model was proposed. The adaptive framework is understood as approaching an integration of the available positioning technology into the context of surrounding wireless communication for a maintainable performance. The positioning model has the capability of delivering indeed accurate, precise and consistent position solutions, and thus is fulfilling the requirements of visually impaired people navigation application, as identified in the adaptive framework
Life That Thrives In Hostility: Mexico\u27s Indigenous Communities and Self-Defense Forces
Explores the emergence of self-defense forces as a third front in Mexico’s drug war. Argues the geographic location of these groups is best predicted by indigenous marginalization and thick social capital. Mexico’s indigenous communities enjoy a de facto autonomy of neglect from the federal state. These communities exercise social bonds in order to ensure their cultural survival. These bonds have been reinforced throughout history, from the Mexican Revolution to the Zapatista Uprising. Under conditions of weakening state institutions and rising cartel extortion/brutality, indigenous communities were the best suited to overcome collective action problems and respond proactively to local violence
Planning the roll-out of hydrogen fueling infrastructure for transportation : a case study in Spain, Andalusia and Seville
Programa de Doctorado en IngenierĂa ElectrĂłnica, Tratamiento de Señales y ComunicacionesThe hydrogen economy is regarded, at present, as an alternative to the existing energy paradigm: a new scheme in which, by using local resources, fuel for transportation can be produced from different sources, and can also be distributed and stored safely. Moreover, if the hydrogen is produced from renewable energy sources, the step towards its use becomes a step towards the sustainability and the reduction of greenhouse gas emissions. One of the major obstacles for the development of this alternative energy model, is the so-called "the chicken and egg dilemma": (1) Users will not purchase a vehicle that uses hydrogen as fuel until they can refuel with a minimum of comfort, that is to say, until a basic infrastructure exists. (2) Car manufacturers will not produce these vehicles until there is a demand for them. (3) No company will deploy hydrogen fueling stations without having a minimum number of potential customers. Therefore, to kick off the transition of the market towards hydrogen vehicles, a planning of the initial development of the infrastructure leading to the solution of this problem is required. In this thesis, different methods to plan the roll-out of hydrogen fueling infrastructure for transportation under different conditions are discussed. These methods are used to propose roll-out strategies for different spatial units and they are applied to the specific cases of Spain, Andalusia, and Seville.Universidad Pablo de Olavide. Departamento de EconomĂa, MĂ©todos Cuantitativos e Historia EconĂłmic
Urban disaster management : a case study of earthquake risk assessment in Cartago, Costa Rica
Natural hazards pose a threat to population, its goods and the environment. Urban areas are particularly vulnerable not only because of the concentration of population but due to the interplay that exists between people, buildings, and technological systems. Disasters have the potential to destroy decades of investment and effort, and cause the deviation of resources intended for primary tasks such as education, health and infrastructure. Disaster management is therefore an important component of urban planning and management as disasters pose a serious threat to sustainable development. There are basically three very important weaknesses in the way disaster management is currently being carried out. The first relates to the reliance upon hazard zonations alone rather than using risk as input for the selection and prioritisation of mitigation strategies. This is unfortunately in part due to the lack of empirical-historical data on damage and due to the high costs of generating and updating building inventories. The second relates to the reliance upon response rather than a concerted effort in both the pre-disaster and the postdisaster phases. The last relates to the lack of disaster information networks which coordinate efforts amongst the many institutions involved. The case of the Costa Rican city of Cartago was chosen as an example of the challenges that lie ahead in terms of geo-information for urban disaster management. The city provides an interesting case study; it represents a typical example of a medium-sized Costa Rican city that is located in a highly hazard-prone area. Cartago is also representative of a financially constrained local government authority with very basic baseline information where plans are elaborated without proper disaster-related information inputs. The research addresses building and population risk by integrating a hazard intensity map, damage curves derived from historical damage records and a building inventory
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