High-Accuracy Low-Cost RTK-GPS for an Unmanned Surface Vehicle

This work presents a low cost RTK-GPS system for localization of unmanned surface vehicles. The system is based on the use of standard low cost L1 band receivers and in the RTKlib open source software library. Mission scenarios with multiple robotic vehicles are addressed as the ones envisioned in the ICARUS search and rescue case where the possibility of having a moving RTK base on a large USV and multiple smaller vehicles acting as rovers in a local communication network allows for local relative localization with high quality. The approach is validated in operational conditions with results presented for moving base scenario. The system was implemented in the SWIFT USV with the ROAZ autonomous surface vehicle acting as a moving base. This setup allows for the performing of a missions in a wider range of environments and applications such as precise 3D environment modeling in contained areas and multiple robot operations.

Low cost carriers: The case of Oporto Airport and its touristic impact in the region

Both Oporto and the North Region of Portugal definitions of tourism have evolved significantly during the past decade. In this journey it is relevant to highlight the contribution of the arrival of Low Cost Carriers (LCCs) at Francisco Sá Carneiro Airport, thus contributing to a rapid expansion of this region as a tourism destination. Hence, this work project aims to understand the touristic and economic impact motivated by the entry of LCCs in Oporto and in the North Region of Portugal and tries to understand if this event was in fact an asset in the development of the aforementioned tourism destinations.

Building 3D City Models: Testing and Comparing Laser Scanning and Low-Cost UAV Data Using FOSS Technologies

Contém resumo

The implications of mandatory low-cost fuel provision

This work studies fuel retail firms’ strategic behavior in a two-dimensional product differentiation framework. Following the mandatory provision of “low-cost” fuel we consider that capacity constraints force firms to eliminate of one the previously offered qualities. Firms play a two-stage game choosing fuel qualities from three possibilities (low-cost, medium quality and high quality fuel) and then prices having exogenous opposite locations. In the highest level of consumers’ heterogeneity, a subgame perfect Nash equilibrium exists in which firms both choose minimum quality differentiation. Consumers’ are worse off if no differentiation occurs in medium and high qualities. The effect over prices from the mandatory “low-cost” fuel law is ambiguous.

Comparing standard and low-cost tools for gradient evaluation along potential cycling paths

Promoting the use of non-motorized modes of transport, such as cycling, is an important contribution to the improvement of mobility, accessibility and equity in cities. Cycling offers a fast and cheap transportation option for short distances, helping to lower pollutant emissions and contributing to a healthier way of life. In order to make the cycling mode more competitive in relation to motorized traffic, it is necessary to evaluate the potential of alternatives from the perspective of the physical effort. One way to do so consists of assessing the suitability of locations for implementing cycling infrastructures. In this work, four tools to determine the gradient along potential cycling paths are compared. Furthermore, an evaluation of the reliability of some low-cost tools to measure this parameter was conducted, by comparison with standard measurements using cartographic plans, on a field case study applied to the city of Braga, Portugal. These tools revealed a good level of accuracy for the planning stage, but proved to be less reliable for use in design.

Princípios para a reabilitação sustentável low cost de edifícios antigos: estudo de um quarteirão no centro da cidade do Porto

Dissertação de mestrado em Construção e Reabilitação Sustentável

Melhoria da eficiência energética em edifícios dos anos 70: implementação de soluções sustentáveis low-tech e low-cost

Dissertação de mestrado em Construção e Reabilitação Sustentáveis

Silicon nanowire arrays coupled with cobalt phosphide spheres as low-cost photocathodes for efficient solar hydrogen evolution

We demonstrate the first example of silicon nanowire array photocathodes coupled with hollow spheres of the emerging earth-abundant cobalt phosphide catalysts. Compared to bare silicon nanowire arrays, the hybrid electrodes exhibit significantly improved photoelectrochemical performance toward the solar-driven H2 evolution reaction.

An empirical analysis of a merger between a network and low-cost airlines

We use a difference-in-difference estimator to examine the effects of a merger involving three airlines. The novelty lies in the examination of this operation in two distinct scenarios: (1) on routes where two low-cost carriers and (2) on routes where a network and one of the low-cost airlines had previously been competing. We report a reduction in frequencies but no substantial effect on prices in the first scenario, while in the second we report an increase in prices but no substantial effect on frequencies. These results may be attributed to the differences in passenger types flying on these routes.

Air services on thin routes: Regional versus low-cost airlines

An examination of the impact in the US and EU markets of two major innovations in the provision of air services on thin routes - regional jet technology and the low-cost business model - reveals significant differences. In the US, regional airlines monopolize a high proportion of thin routes, whereas low-cost carriers are dominant on these routes in Europe. Our results have different implications for business and leisure travelers, given that regional services provide a higher frequency of flights (at the expense of higher fares), while low-cost services offer lower fares (at the expense of lower flight frequencies). Keywords: air transportation; regional jet technology; low-cost business model; thin markets. JEL Classification Numbers: L13; L2; L93.

Construcció d¿un cercador de viatges low cost utilitzant tècniques de web scraping

Cercador web de viatges utilitzant tècniques de web scraping.

Serological diagnosis of Chagas disease: evaluation and characterisation of a low cost antigen with high sensitivity and specificity

In spite of evident progress in the serology of Chagas disease, the requirement for new diagnostic antigens persists. We have evaluated different antigens obtained from Trypanosoma cruzi grown in medium rich in nutrients or under nutrient stress, autoclaved or sonicated and fractionated by differential centrifugation. The resulting antigens were evaluated for diagnosis of Chagas disease using ELISA. Immunofluorescence of the parasites demonstrated that nutrient stress induced changes in the distribution and density of antigens recognised by a pool of sera from experimentally infected mice. When evaluated using ELISA, it was evident that most fractions had good sensitivity but poor specificity. Surprisingly, the best specificity and sensitivity was observed with parasites cultured under nutrient stress and autoclaved. Furthermore this antigen had low cross reactivity with sera from other parasitic diseases, Leishmaniasis in particular. Western blot analysis demonstrated that autoclaving seems to non-specifically eliminate cross-reactive antigens. In conclusion, autoclaving epimastigotes of T. cruzi, after nutrient stress, allowed us to obtain an antigen that could be used in the serological diagnosis of Chagas disease.

Breakguides: Creació d'una empresa de guiatge low cost

El projecte es planteja el repte de cobrir un forat en l’oferta turística seguint la fórmula low cost: el guiatge turístic. La idea de la empresa que volem estudiar i crear (BREAKGUIDES) és la de poder oferir els serveis de guiatge, ja siguin guies correu o guies locals en destinació, seguint una fórmula low cost que s’adapti al nou perfil de turista i al seu pressupost. L’empresa tindrà un perfil semblant al d’una xarxa social que ofereixi serveis de guiatge a canvi d’un petit sou i la manutenció

Schistosoma mansoni in a low-prevalence area in Brazil: the importance of additional methods for the diagnosis of hard-to-detect individual carriers by low-cost immunological assays

Schistosomiasis diagnosis is based on the detection of eggs in the faeces, which is laborious and lacks sensitivity, especially for patients with a low parasite burden. Immunological assays for specific antibody detection are available, but they usually demonstrate low sensitivity and/or specificity. In this study, two simple immunological assays were evaluated for the detection of soluble Schistosoma mansoni adult worm preparation (SWAP) and egg-specific IgGs. These studies have not yet been evaluated for patients with low parasite burdens. Residents of an endemic area in Brazil donated sera and faecal samples for our study. The patients were initially diagnosed by a rigorous Kato-Katz analysis of 18 thick smears from four different stool samples. The ELISA-SWAP was successful for human diagnosis with 90% sensitivity and specificity, confirming the Kato-Katz diagnosis with nearly perfect agreement, as seen by the Kappa index (0.85). Although the ELISA-soluble S. mansoni egg antigen was 85% sensitive, it exhibited low specificity (80%; Kappa index: 0.75) and was more susceptible to cross-reactivity. We believe that immunological assays should be used in conjunction with Kato-Katz analysis as a supplementary tool for the diagnosis of schistosomiasis for patients with low infection burdens, which are usually hard to detect.

Consumer Advisory Bulletin, "Free" and "Low-Cost" Computers: Beware of Unexpected Costs, January 2008

The Attorney General’s Consumer Protection Division receives hundreds of calls and consumer complaints every year. Follow these tips to avoid unexpected expense and disappointments. This record is about: "Free" and "Low-Cost" Computers: Beware of Unexpected Costs