801 research outputs found
Tourism: an alternative to development?: reconsidering farming, tourism and conservation incentives in Northwest Yunnan mountainous communities
In the last decade, tourism has developed rapidly in the mountainous areas of northwest Yunnan. This growth has led to substantial economic and social changes, with resulting environmental consequences. This article uses a case study to illustrate how local farmers involved in tourism changed their agricultural practices as a result of the transformations that took place in the area. The aim was to examine tourism's expected benefits of poverty alleviation and conservation incentives. Tourism investments were found to have been adopted only by households with available cash and labor, whereas they remained inaccessible for the poor, small landowners who most needed a new source of income and used their land more exhaustively. Relatively rich, large landowners did not take the opportunity to reduce their agricultural activities. Instead, they used supplementary incomes earned from tourism to hire external labor to cultivate their land more intensely. Tourism development failed to generate real incentives for mountain farmers to adopt more conservation measures and prevent soil erosion and nonpoint source agricultural water pollution, which currently constitute serious environmental problems for mountain environments in Yunnan. This article presents recommendations based on the conclusions of the study
Hurricanes on tidally locked terrestrial planets: Fixed surface temperature experiments
In this work, we study the presence of hurricanes on exoplanets. Tidally
locked terrestrial planets around M dwarfs are the main targets of space
missions looking to discover habitable exoplanets. The question of whether
hurricanes can form on this kind of planet is important for determining their
climate and habitability. Using a high-resolution global atmospheric
circulation model, we investigated whether there are hurricanes on tidally
locked terrestrial planets under fixed surface temperatures. The relevant
effects of the planetary rotation rate, surface temperature, and bulk
atmospheric compositions were examined. We find that hurricanes can form on the
planets but not on all of them. For planets near the inner edge of the
habitable zone of late M dwarfs, there are more numerous and stronger
hurricanes on both day and night sides. For planets in the middle and outer
ranges of the habitable zone, the possibility of hurricane formation is low or
even close to zero, as has been suggested in recent studies. Earth-based
hurricane theories are applicable to tidally locked planets only when the
atmospheric compositions are similar to that of Earth. However, if the
background atmosphere is lighter than H2O, hurricanes can hardly be produced
because convection is always inhibited due to the effect of the mean molecular
weight, similarly to the case of Saturn. These results have broad implications
on the precipitation, ocean mixing, climate, and atmospheric characterization
of tidally locked planets. Finally, A test with a coupled slab ocean and an
Earth-like atmosphere in a tide-locked orbit of ten Earth days demonstrates
that there are also hurricanes present in the experiment
A GIS approach towards estimating tourist's off-road use in a mountainous protected area of Northwest Yunnan, China
To address the environmental impacts of tourism in protected areas, park managers need to understand the spatial distribution of tourist use. Standard monitoring measures (tourist surveys and counting and tracking techniques) are not sufficient to accomplish this task, in particular for off-road travel. This article predicts tourists' spatial use patterns through an alternative approach: park accessibility measurement. Naismith's rule and geographical information system's anisotropic cost analysis are integrated into the modeling process, which results in a more realistic measure of off-road accessibility than that provided by other measures. The method is applied to a mountainous United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage Site in northwest Yunnan Province, China, where there is increasing concern about potential impacts of unregulated tourist use. Based on the assumption that accessibility tends to attract more tourists, a spatial pattern of predicted off-road use by tourists is derived. This pattern provides information that can help park managers develop strategies that are effective for both tourism management and species conservation
Anderson Acceleration for Partially Observable Markov Decision Processes: A Maximum Entropy Approach
Partially observable Markov decision processes (POMDPs) is a rich
mathematical framework that embraces a large class of complex sequential
decision-making problems under uncertainty with limited observations. However,
the complexity of POMDPs poses various computational challenges, motivating the
need for an efficient algorithm that rapidly finds a good enough suboptimal
solution. In this paper, we propose a novel accelerated offline POMDP algorithm
exploiting Anderson acceleration (AA) that is capable of efficiently solving
fixed-point problems using previous solution estimates. Our algorithm is based
on the Q-function approximation (QMDP) method to alleviate the scalability
issue inherent in POMDPs. Inspired by the quasi-Newton interpretation of AA, we
propose a maximum entropy variant of QMDP, which we call soft QMDP, to fully
benefit from AA. We prove that the overall algorithm converges to the
suboptimal solution obtained by soft QMDP. Our algorithm can also be
implemented in a model-free manner using simulation data. Provable error bounds
on the residual and the solution are provided to examine how the simulation
errors are propagated through the proposed algorithm. Finally, the performance
of our algorithm is tested on several benchmark problems. According to the
results of our experiments, the proposed algorithm converges significantly
faster without degrading the solution quality compared to its standard
counterparts
Molecular Weight and Thermal Properties of Fiber Reinforced Polyamide-Based Composites Throughout the Direct Long-Fiber Reinforced Thermoplastic Process
The D-LFT process is an efficient and cost-effective process and includes two twin-screwextruders, a conveyer, and a compression molding machine. It is imperative to understand how the process sequence affects molecular weight and thermal properties of composite materials during the D-LFT process. The main objective of this study was to characterize variation in molecular weight and thermal properties of two types of polyamide (PA)-based composite materials (glass fiber reinforced PA6 composites and carbon fiber reinforced PA66 composites) through the D-LFT process. Samples were taken from different locations along the D-LFT process and characterized using triple detection gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), andfourier-transform infrared spectroscopy (FTIR). It was found thatmolecular weightof both PA-based composites increased after the second extruderby branching of PA molecules. Therefore, process conditions after the secondextruderneed to be carefully adjusted to design PA-based D-LFT products
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