Timber structures can be degraded during their life both by structural problems and by biological degradation factors like fungi and insects. The occurrence of those biodegradation agents could lead to a loss of their structural integrity, in the absence of appropriate maintenance. An early assessment of the decay is even more important when the wooden structures are part of historical buildings, in the interest of conservation of cultural heritage.
This article presents an application of microwave reflectometry for the in situ evaluation of timber structures. The measurement system allows detecting anomalies inside the material in a non-destructive and non-invasive manner.
The reflection coefficient is measured by means of a vector network analyzer (VNA) using a double-ridge antenna which transmits the continuous-wave (CW) microwave signal and receives the signal reflected by the material under investigation.
Measurements on laboratory models demonstrated the feasibility of the method. Results obtained on timber beam sections, compared with the findings of traditional investigation methodologies, demonstrate the potentiality of microwave reflectometry, suggesting its possible usefulness during the diagnostic phase as a non-invasive tool for preliminary screening. 相似文献
Historical park visitation and weather data, taken at the daily time scale from 2000 to 2009 for Pinery Provincial Park in southern Ontario (Canada), were analysed as an objective measure of the weather sensitivity, temperature thresholds, and potential impacts of projected climate change for park visitation. Three seasonal weather-visitation models were constructed using multivariable linear regression (peak, shoulder, off-season). To account for both natural and institutional seasonality, the weather-visitation models included both climatic (temperature, precipitation) and social (weekends, holidays) variables, which demonstrated equably comparable effects on visitation across the three models. Critical temperature thresholds were identified for each season using one-way analysis of variance to determine the range of temperatures within which the threshold was evident; the specific degree of temperature associated with the threshold was identified within the seasonal regression models. Temperatures over 33 °C during the peak season and over 29 °C during the shoulder season indicated critical thresholds at which point conditions that were ‘too hot’ for some caused a decline in visitation. Furthermore, temperatures below 11 °C indicated another critical threshold, where conditions were ‘too cold’ for most and therefore park visitation was less sensitive to temperature variability below this threshold. A partial sensitivity analysis for the impact of a warmer, wetter climate on park visitation was conducted, illustrating the effect of a 1 °C to 5 °C warming in maximum temperatures, coupled with a 5% to 15% increase in total precipitation. In response to projected climate change, the weather-visitation models suggested that for each additional degree of warming experienced, despite the negative effects of increasing precipitation and more frequent heat extremes, annual park visitation could increase by 3.1%, annually. The projected increase in park visitation as a result of rising temperatures was mainly associated with shoulder season visitation, with only minor increases in peak season visitation. 相似文献
High tourism growth in single-asset tourism cities is often associated with a standardization of supply of products and services by tourism entrepreneurs. However, and in contrast to this common-sense view, tourism growth in specific urban tourism milieus in the ‘sun-sea-sand’ tourism city of Antalya has stimulated tourism entrepreneurs to differentiate their products. Contrary to most economic-geography literature on spatial clusters, evolutionary economic geographers argue that inter-industry relations of (un)related variety are crucial in inter-firm differentiation. The aim of the paper is to define the factors that influence tourism-firm differentiation in the single-asset tourism city of Antalya. The empirical research is theoretically informed by evolutionary economic-geography literature, and pays much attention to the role different urban sub-milieus play in tourism-firm differentiation. It is the first research on the relation between (un)related variety and tourism-firm differentiation in tourism studies. The empirical research is based on primary data collected by a firm-level survey (hotels, restaurants, jewellery- and retail-trade firms) in the city of Antalya. The factors that influence tourism-firm differentiation are explored by using quantitative methods of analysis (an econometric logit-regression model and a correspondence analysis). The main result of the empirical research is that investments in firms in related sectors, in our case jewellery companies and hotels, are positively and significantly related to tourism-firm differentiation. In addition, the location tourism firms in areas visited by a mix of consumers (tourists and locals) also is positively and significantly related to inter-firm differentiation whereas urban milieus visited by locals only have a negative effect. 相似文献
Over the last 40 years, warmer temperatures have caused a considerable decrease in snow cover on glaciers and high rates of glacial melt, particularly in tropical mountains. In the Bolivian Andes, the Chacaltaya glacier (5400 masl) had been a tourist destination known as the highest ski slope in the world since 1939. As a result of climate change, skiing has not been possible after 1987 and the glacier definitely disappeared in 2009. However, since 2005, the place has become a new attraction for tourists. Travel agencies in La Paz now offer day trips to the Chacaltaya site. In order to understand the present attraction of the site and its potential for reproduction elsewhere, 25 semi-structured interviews were conducted with various categories of stakeholders involved in the tourism industry in La Paz, and archives and images were analysed. Our results show that the multifunctional character of this tourist site, including easy access to a summit, beautiful views, acclimatisation to altitude and opportunity to experience snow, are key factors in its renewed attraction for visitors, together with, to a lesser extent, the incentive of being able to watch a famous and evident full disappearance of a glacier and former ski slope. The stakeholders' groups share general views and perceptions about environmental changes and about the qualities of the site, but they also differ in terms of projects and evaluation of potential attractiveness. In particular, the development of the visibility of climate change impacts on mountain environment is valued by experts or by members of the Andean Club, but not by travel agencies. The example of Chacaltaya shows that multifunctional tourist sites may still be attractive in the future. 相似文献
As a knowledge domain, contemporary indigenous tourism is framed in reference to cultures conventionally recognized as ‘indigenous,’ and engages this almost exclusively from a supply-side perspective. This paper reimagines indigeneity and indigenous tourism as embracing also the other 94% of global population. From a utilitarian perspective, this inclusion of ‘nonconventional indigenous people’ harbors opportunities to advance the sustainability agenda by reconnecting modern mainstream cultures, through personal exposure in dispersed settings, with ancestral roots and associated sustainable livelihoods. Such reconnections are framed as a form of re-indigenization that may be especially attractive to ‘travel promiscuous’ diasporic populations such as those found in the ‘settler’ countries of Canada, United States, Australia, and New Zealand. Articulation of this concept could be facilitated by existing knowledge domains and products in heritage tourism, rural tourism, and urban tourism, as well as sustainable tourism. Rather than usurping conventional indigenous efforts to re-indigenize and re-empower, it is contended that the nonconventional dimension can coexist with and even reinforce the latter, while enriching the dimensions of indigenous tourism as a dynamic knowledge domain. 相似文献