Thinned spectrum radar waveforms Cook, M R; Higgins, T; Shackelford, A K
2010 International Waveform Diversity and Design Conference,
2010-Aug.
Conference Proceeding
Open access
Small phase perturbations applied to a stepped-frequency or linear-frequency-modulated radar waveform have been proposed as a means to generate frequency nulls in the spectrum of the transmitted ...waveform. By nulling selected frequencies (or thinning) in the spectrum of transmitted pulses, the interference between the transmitted and received signals is reduced, which facilitates the spectral cohabitation of multiple RF users. Preliminary experimental results of two methods of spectral nulling are presented with consideration to in-band and out-of-band interference. Range processing is examined to determine the effects of the phase perturbation on radar operations.
In applied econometrics, we tend to tackle specification problems one at a time rather than considering them jointly. This has serious consequences for statistical inference. One example of this is ...considering autocorrelation and autoregressive conditional heteroscedasticity (ARCH) separately. In this article we consider a linear regression model with random coefficient autoregressive disturbances that provides a convenient framework to analyze autocorrelation and ARCH simultaneously. Our stationarity conditions and testing results reveal the strong interaction between ARCH and autocorrelation. An empirical example of testing the unbiasedness of experts' expectations of inflation demonstrates that neglecting conditional heteroscedasticity or misspecifying the autocorrelation structure might result in unreliable inference.
The IAWQ Task Group's Activated Sludge Model No. 2 (ASM2) was introduced by Gujer et al. (1995). Its development offers an improvement over Activated Sludge Model No. 1 (ASM1) by including a term for ...phosphorus accumulating organisms in the simulation of biological phosphorus removal processes. ASM2 was used to explain a rise in phosphate levels due to an accumulation of polyhydroxyalkanoates in an alternating type activated sludge pilot plant (Isaacs et al., 1995). The addition of a reaction term describing the rate of denitrification by phosphate accumulating organisms allowed the model to more accurately describe the data. In another study, three submodels to ASM2 were proposed to account for glycogen storage and anoxic uptake of soluble orthophosphate (Mino et al., 1995b). This study also characterized a group of organisms causing deterioration of phosphate removal.
Scientific papers published during 1998 on aerobic suspended culture processes (primarily activated sludge) for treating polluted water and wastewater are surveyed. Key advances have been made in ...modeling and kinetics, while other research has focused on process microbiology, nitrogen and phosphorus control in aerated reactors, and the fate and effects of xenobiotics in activated sludge processes. Further work has been done on the design, operation, and control of treatment facilities for industrial wastewaters, as well as on oxygen transfer and solids separation.
The goals were to (1) clarify high risk individuals into one of five stages of readiness for consistent condom use based on the Transtheoredcal Model of behavior change (e.g., Prochaska, Norcross and ...DiClemente, 1994); (2) investigate whether frequency of condom use was different for vaginal vs. anal sex, and for steady vs. other partners; and (3) explore whether condom use was related to several demographic variables. Street interviews were conducted in six major geographic areas across the United States on a diverse sample of 345 individuals engaging in high HIV-risk behaviors. Percentages of individuals found in each of five stages of condom use were: 36% Precontemplators, 15% Contemplators, 7% in Preparation, 7% in Action, and 35% in Maintenance. Individuals used condoms more with other, casual partners than with a steady partner, and slightly more when engaging in anal sex rather than vaginal sex. Condoms were also used more by: men, Caucasians, non-heterosexuals, and those who were not in a steady relationship than by others not in these categories. Still, the majority of high-risk individuals were not using condoms and were not prepared to start This presents an urgent need for effective interventions to encourage condom use.
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