64 resultados para Atmospheric radio refractivity.
Resumo:
El objetivo de este trabajo es determinar las características básicas de la entonación de los eslóganes publicitarios tanto de radio como de televisión. Con este propósito se analizan los valores de la Fº de las vocales que aparecen en el fragmento que corresponde al eslogan. Para evitar en la medida de lo posible las diferencias que pueden venir determinadas por el soporte físico en el que aparecen los eslóganes publicitarios, se escogió el mismo producto, diferentes marcas de vehículos, y se seleccionaron aquellos enunciados óptimos para un posterior análisis de la señal. Para la segmentación de los eslóganes dentro de los enunciados publicitarios y el análisis de las curvas melódicas se utilizó el programa PRAAT. Para cada enunciado se han ido anotando los valores de la F0 de cada vocal, teniendo en cuenta las tres partes de cada unidad melódica: el anacrusis, el cuerpo y la inflexión final. Para minimizar las variaciones debidas al tono de voz característico de cada locutor, se ha procedido a una estandarización de los valores frecuenciales. Los resultados obtenidos muestran que todos los eslóganes analizados presentan énfasis, que a veces afecta a una parte del contorno (anacrusis, cuerpo e inflexión final), a veces a más de una y otras, incluso a todo el contorno. Aunque en radio y televisión se suelen presentar características prosódicas similares, existen características propias del medio de comunicación que se utiliza.
Resumo:
We model the wavelength-dependent absorption of atmospheric gases by assuming constant mass absorption coefficients in finite-width spectral bands. Such a semigray atmosphere is analytically solved by a discrete ordinate method. The general solution is analyzed for a water vapor saturated atmosphere that also contains a carbon dioxide-like absorbing gas in the infrared. A multiple stable equilibrium with a relative upper limit in the outgoing long-wave radiation is found. Differing from previous radiative–convective models, we find that the amount of carbon dioxide strongly modifies the value of this relative upper limit. This result is also obtained in a gray (i.e., equal absorption of radiation at all infrared wavelengths) water vapor saturated atmosphere. The destabilizing effect of carbon dioxide implies that massive carbon dioxide atmospheres are more likely to reach a runaway greenhouse state than thin carbon dioxide ones
Resumo:
The aim of this project is to accomplish an application software based on Matlab to calculate the radioelectrical coverage by surface wave of broadcast radiostations in the band of Medium Wave (WM) all around the world. Also, given the location of a transmitting and a receiving station, the software should be able to calculate the electric field that the receiver should receive at that specific site. In case of several transmitters, the program should search for the existence of Inter-Symbol Interference, and calculate the field strenght accordingly. The application should ask for the configuration parameters of the transmitter radiostation within a Graphical User Interface (GUI), and bring back the resulting coverage above a map of the area under study. For the development of this project, it has been used several conductivity databases of different countries, and a high-resolution elevation database (GLOBE). Also, to calculate the field strenght due to groundwave propagation, it has been used ITU GRWAVE program, which must be integrated into a Matlab interface to be used by the application developed.
Resumo:
Cognitive radio networks sense spectrum occupancy and manage themselvesto operate in unused bands without disturbing licensed users. The detection capability of aradio system can be enhanced if the sensing process is performed jointly by a group of nodesso that the effects of wireless fading and shadowing can be minimized. However, taking acollaborative approach poses new security threats to the system as nodes can report falsesensing data to reach a wrong decision. This paper makes a review of secure cooperativespectrum sensing in cognitive radio networks. The main objective of these protocols is toprovide an accurate resolution about the availability of some spectrum channels, ensuring thecontribution from incapable users as well as malicious ones is discarded. Issues, advantagesand disadvantages of such protocols are investigated and summarized.