• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • Tagged with
  • 3
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Valuation of Forest Non-Market Values : An empirical study in Northern Sweden

Otterbeck, Daniel, Lundstedt, Fredrik January 2017 (has links)
The purpose of this study was to investigate the Willingness to Pay (WTP) of conserving a ten hectares forest area in Rutvik, amongst the population of Luleå municipality. Furthermore, the study investigated the factors influencing the WTP and its impact on a Faustmann-Hartman rotation period. The tested influential factors were both socio-economic and attitudes towards use values and non-use vales that a forest stand can provide the society. The study used an empirical approach, were a survey was created using a Contingent Valuation Method (CVM). The survey consisted of three parts, where the first part asked the respondents general questions, the second part let the respondent rate different type of forest values and finally a last part where an open-ended question asked the respondents of their maximum WTP. The results indicated that the mean WTP was equal to 15.9 SEK for the total forest area. The results also demonstrated that income had a significant positive impact on WTP and that living nearer the targeted forest gave a higher probability of having a WTP. The only service that indicated significant result was altruistic values, which value had a positive impact on the WTP. It also indicated that the researched WTP extended the traditional Faustmann rotation formula from 56 to 58 years for pine and 75 to 78 years for spruce.
2

Characterization of Eight Potentially Hazardous Near Earth Asteroids: Rotation Period Analysis and Structure Modeling Via Light Curve Inversion Techniques

Hicks, Stacy Jo 01 July 2018 (has links)
The term “homeland security”, seems to have become synonymous with terrorism in the minds of the general public. However, there are other threats to the security of the United States homeland that can be just as, if not more, devastating than terrorism. Included among these other threats is the potential of an asteroid collision with Earth. Historically, asteroid impact events have been responsible for the devastation of our planet and many of the mass extinction events encountered throughout the geologic record. Knowledge of physical parameters such as structure and rotational dynamics of the asteroid are critical parameters in developing interception and deflection techniques, as well as assessing the risk associated with these bodies and mitigation planning in the event of impact. This thesis encompasses the study of eight potentially hazardous asteroids identified in conjunction with NASA’s OSIRIS REX Mission and observed via the Target Asteroid Project, along with observations from the Robotically Controlled Telescope, and the Asteroid Light Curve Database of Photometry. Photometric data was extracted from all observations. Rotation periods of each target were confirmed using Lomb-Scargle time series analysis, with possible secondary periods indicated in the cases of Hathor (2.2169 hours), Bede (161.1501 hours), and Phaethon (4.5563 hours). Shape models for 2002 FG7, 2004 JN13, and Icarus were produced using light curve inversion techniques These are believed to be the first such models for these asteroids.
3

Understanding the brightness variations of Sun-like stars on timescales of stellar rotation

Amazo Gomez, Eliana Maritza 27 October 2020 (has links)
El brillo solar varía en escalas de tiempo de minutos a décadas. En particular, la variabilidad fotométrica observada puede relacionarse directamente con el período de rotación. Nuestro conocimiento de este vínculo permite extrapolaciones desde el Sol a otras estrellas. Incluso después de los exitosos estudios estelares logrados por las misiones Kepler o TESS, todavía hay una falta de información en los registros fotométricos de los períodos de rotación de estrellas similares al Sol. Los perfiles de curvas de luz no periódicas, la amplitud de modulación baja (los generados por la aparición aleatoria de características magnéticas y su rápida evolución, en comparación con la escala de tiempo de rotación) son las principales razones poco confiable estimación de la periodicidad en el Sol y sus análogos estelares. Esto indica que las estrellas con un perfil de brillo solar similar también podrían enfrentar un problema de detectabilidad del período de rotación. Lo que implica que solo una fracción de los sistemas similares a los solares se han analizado adecuadamente. Propongo en esta Tesis que una señal clara y optimizada del período de rotación puede ser determinada de manera confiable a partir del perfil del gradiente en el espectro de potencia (GPS) de las series de tiempo de brillo, también denominadas curvas de luz. El GPS es un método novedoso destinado a determinar los períodos de rotación de estrellas como el Sol (es decir, con un perfil de variabilidad de brillo similar). Adicionalmente, el método nos da valiosa información sobre la relación entre fáculas y manchas, lo que, en consecuencia, podría ayudarnos a interpretar la superficie estelar. Este trabajo se basa en el análisis de series de tiempo fotométricas de alta calidad adquiridas por el telescopio Kepler, mediciones de alta estabilidad y alta precisión de la misión SOHO / VIRGO y modelos detallados de variaciones de brillo solar. El método GPS se propone, se desarrolla y prueba con éxito en esta tesis.

Page generated in 0.1088 seconds