2 research outputs found
Echo Delay and Overlap with Emitted Orientation Sounds and Doppler-shift Compensation in the Bat, Rhinolophus ferrumequinum
The compensation of Doppler-shifts by the bat, Rhinolophusferrumequinum,
functions only when certain temporal relations between the echo
and the emitted orientation sound are given. Three echo configurations
were used:
a) Original orientation sounds were electronically Doppler-shifted and
played back either cut at the beginning (variable delay) or at the end (variable
duration) of the echo.
b) Artificial constant frequency echoes with variable delay or duration
were clamped to the frequency of the emitted orientation sound at different
Doppler-shifts.
c) The echoes were only partially Doppler-shifted and the Doppler-shifted
component began after variable delays or had variable durations.
With increasing delay or decreasing duration of the Doppler-shifted echo
the compensation amplitude for a sinusoidally modulated + 3 kHz Dopplershift
(modulation rate 0.08 Hz) decreases for all stimulus configurations
(Figs. 1, 2, 3).
The range of the Doppler-shift compensation system is therefore limited
by the delay due to acoustic travel time to about 4 m distance between
bat and target. In this range the overlap duration of the echo with the
emitted orientation sound is always sufficiently long, when compared with
data on the orientation pulse length during target approach from Schnitzler
(1968) (Fig. 5)
Um simulador dinâmico do crescimento de uma cultura de cana-de-açúcar A dynamic simulator of the sugarcane crop growth
Este trabalho descreve a primeira versão de um simulador matemático-fisiológico do crescimento diário de uma cultura de cana-de-açúcar (SIMCANA) em resposta às condições do ambiente durante a estação de crescimento. SIMCANA resume a maior parte das informações disponíveis concernentes aos processos fisiológicos da cultura de cana-de-açúcar. Esta sua versão não incluí os processos degerminação e florescimento, havendo necessidade de especificar as condições da cultura no primeiro dia de simulação. Em função das condições diárias de radiação solar global, temperatura máxima e mínima, umidade relativa do ar, SIMCANA calcula as taxas de fotossíntese, respiração e crescimento da cultura, as taxas de senescência das folhas e raízes, a massa seca das folhas, colmos e raízes, e o índice de área foliar. Embora várias relações empíricas tenham sido usadas, SIMCANA parece ser capaz de simular o crescimento da cultura de cana-de-açúcar.<br>The first version of a mathematical-physiological simulator of the daily growth of a sugarcane crop (SIMCANA) as a function of the environmental conditions during the growing season is described. SIMCANA summarizes most of the available information regarding to the physiological processes of the sugarcane crop. This version does not include the germination and flowering processes, therefore it is necessary to specify the crop conditions at the first day of simulation. Given the daily conditions of global solar radiation, maximum and minimum temperature, and the relative humidity, SIMCANA computes the rates of crop photosynthesis, respiration, and growth, the senescence rates for leaves and roots, the dry mass of leaves, stems, and roots, and the leaf area index. Although several empirical relations have been used, SIMCANA seems to be able to simulate the sugarcane crop growth