Interference Aspects of Adaptive Modems over Slow Rayleigh Fading Channels

Adaptive modulation can achieve channel capacity gains by adapting the number of bits per transmission symbol on a burst-by-burst basis, in harmony with channel quality fluctuations. This is demonstrated in the paper for target bit error rates of 1 and 0.01%, respectively, in comparison to conventional fixed modems. However, the achievable gains depend strongly on the prevalent interference levels and hence interference cancellation is invoked on the basis of adjusting the demodulation decision boundaries after estimating the interfering channel’s magnitude and phase. Using the modem-mode switching levels of Table X and with the aid of interference cancellation, target BERs of 1 and 0.01% can be maintained over slow-fading channels for a wide range of channel Signal-to-noise ratios (SNR) and Signal-to-interference ratios (SIR), as seen in Figs. 20 and 21, respectively. Index Terms—Burst-by-burst adaptive modulation (modems), cochannel interference, interference cancellation

Tips for Using Photovoice in Evaluation of Extension Programs

Photovoice is a technique in which a facilitator guides a participant to produce a photograph and accompanying caption that reflects the participant\u27s unique views regarding a topic. The photovoice process is designed to be used with a wide range of audiences. This article describes ways Extension educators can incorporate photovoice into the evaluation of Extension programs and identifies issues they should consider when doing so

Testing evolutionary models of senescence in a natural population: age and inbreeding effects on fitness components in song sparrows

Mutation accumulation (MA) and antagonistic pleiotropy (AP) have each been hypothesized to explain the evolution of ‘senescence’ or deteriorating fitness in old age. These hypotheses make contrasting predictions concerning age dependence in inbreeding depression in traits that show senescence. Inbreeding depression is predicted to increase with age under MA but not under AP, suggesting one empirical means by which the two can be distinguished. We use pedigree and life-history data from free-living song sparrows (Melospiza melodia) to test for additive and interactive effects of age and individual inbreeding coefficient (f) on fitness components, and thereby assess the evidence for MA. Annual reproductive success (ARS) and survival (and therefore reproductive value) declined in old age in both sexes, indicating senescence in this short-lived bird. ARS declined with f in both sexes and survival declined with f in males, indicating inbreeding depression in fitness. We observed a significant age×f interaction for male ARS (reflecting increased inbreeding depression as males aged), but not for female ARS or survival in either sex. These analyses therefore provide mixed support for MA. We discuss the strengths and limitations of such analyses and therefore the value of natural pedigreed populations in testing evolutionary models of senescence

Characterization of the Radioactive Sludge from the ORNL MVST Waste Tanks

Over the last several years most of the sludge and liquid from the Liquid Low-Level Waste (LLLW) tanks at ORNL has been transferred and consolidated in the Melton Valley Storage Tanks (MVST). The contents of the MVST tanks at the time the sludge samples were collected for this report included the original inventory in the MVSTs along with the sludge and liquid from the Bethel Valley Evaporator Service Tanks (BVEST), Old Hydrofracture (OHF) tanks, and the Gunite and Associated Tanks (GAAT). During the summer of 2001 full core samples of sludge were collected from the MVST tanks. The purpose of this sampling campaign was to characterize and validate that the current radiochemical and chemical contents of the MVST sludge, which was needed to meet the contract agreements prior to the transfer of the waste to another DOE contractor for processing. This report only discusses the analytical characterization of the sludge from the MVST waste tanks. The isotopic data presented in this report supports the position that fissile isotopes of uranium ({sup 233}U and {sup 235}U) and plutonium ({sup 239}Pu and {sup 241}Pu) were ''denatured'' as required by the administrative controls stated in the ORNL LLLW waste acceptance criteria (WAC). In general, the MVST sludge was found to be hazardous by RCRA characteristics based on total analysis of chromium, mercury, and lead. Also, the alpha activity due to transuranic isotopes was well above the 100 nCi/g limit for TRU waste. The characteristics of the MVST sludge relative to the WIPP WAC limits for fissile gram equivalent, plutonium equivalent activity, and thermal power from decay heat, were estimated from the data in previous reports and found to be far below the upper boundary for any of the remote-handled transuranic waste (RH-TRU) requirements for disposal of the waste in WIPP. Therefore, the WIPP WAC limits were not evaluated for this set of samples

Theory and experiment of the ESR of Co2+^{2+} in Zn2_2 % (OH)PO4_4 and Mg2_2(OH)AsO4_4

Experiments of Electron Spin Resonance (ESR) were performed on Co$$ substituting Zn$^{2+}$ or Mg$^{2+}$ in powder samples of Zn$_2$(OH)PO$_4$ and Mg$_2$(OH)AsO$_4$. The observed resonances are described with a theoretical model that considers the departures from the two perfect structures. It is shown that the resonance in the penta-coordinated complex is allowed, and the crystal fields that would describe the resonance of the Co$^{2+}$ in the two environments are calculated. The small intensity of the resonance in the penta-coordinated complex is explained assuming that this site is much less populated than the octahedral one; this assumption was verified by a molecular calculation of the energies of the two environments, with both Co and Zn as central ions in Zn$_2$(OH)PO$_4$.Comment: 43 pages, LaTex file, 6 figures, EPS. submitted to Journal of Physics Condens

Characterization of selected waste tanks from the active LLLW system

From September 1989 through January of 1990, there was a major effort to sample and analyze the Active Liquid-Low Level Waste (LLLW) tanks at ORNL which include the Melton Valley Storage Tanks (MVST) and the Bethel Valley Evaporator Service Tanks (BVEST). The purpose of this report is to summarize additional analytical data collected from some of the active waste tanks from November 1993 through February 1996. The analytical data for this report was collected for several unrelated projects which had different data requirements. The overall analyte list was similar for these projects and the level of quality assurance was the same for all work reported. the new data includes isotopic ratios for uranium and plutonium and an evaluation of the denature ratios to address criticality concerns. Also, radionuclides not previously measured in these waste tanks, including 99Tc and 237Np, are provided in this report

Inductively coupled plasma mass spectrometer installation modifications in a radioactive contaminated laboratory for the analysis of DOE radioactive waste streams

The operation and maintenance of a complex analytical instrument such as an inductively coupled plasma mass spectrometer in a radioactive contaminated environment presents unique problems and challenges that have to be considered in the purchasing and installation process. Considerations such as vendor experience, typical radiation levels, sample matrices encountered during sample analysis, instrument accessibility for maintenance, and upkeep must be incorporated into the decision process. The Radioactive Materials Analytical Laboratory (RMAL) at Oak Ridge National Laboratory (ORNL) recently purchased and installed an inductively coupled plasma mass spectrometer for the analysis of Department of Energy (DOE) radioactive waste streams. This presentation will outline the purchasing decision, installation of the instrument, and how the modifications needed to operate in a radioactive contaminated laboratory do not significantly impact the daily operation and maintenance requirements of the instrument. Also, a contamination survey of the system will be presented which demonstrates the contamination levels in the instrument from the sample introduction system to the detector

Characterization of the MVST waste tanks located at ORNL

During the fall of 1996 there was a major effort to sample and analyze the Active Liquid Low-Level Waste (LLLW) tanks at ORNL which include the Melton Valley Storage Tanks (MVST) and the Bethel Valley Evaporator Service Tanks (BVEST). The characterization data summarized in this report was needed to address waste processing options, address concerns of the performance assessment (PA) data for the Waste Isolation Pilot Plant (WIPP), evaluate the characteristics with respect to the waste acceptance criteria (WAC) for WIPP and Nevada Test Site (NTS), address criticality concerns, and meet DOT requirements for transporting the waste. This report only discusses the analytical characterization data for the MVST waste tanks. The isotopic data presented in this report support the position that fissile isotopes of uranium and plutonium were ``denatured`` as required by administrative controls. In general, MVST sludge was found to be both hazardous by RCRA characteristics and the transuranic alpha activity was well about the limit for TRU waste. The characteristics of the MVST sludge relative to the WIPP WAC limits for fissile gram equivalent, plutonium equivalent activity, and thermal power from decay heat, were estimated from the data in this report and found to be far below the upper boundary for any of the remote-handled transuranic waste requirements for disposal of the waste in WIPP

Comparison of SW-846 method 3051 and SW-846 method 7471A for the preparation of solid waste samples for mercury determination

This report describes experimental studies to evaluate the use of EPA SW-846 method 3051 for preparation and dissolution of solid samples for Hg analysis. The study showed that the method is effective in dissolution of four sample types without significant loss of Hg. Based on results of this study, method 3051 was used for analysis of high radioactive waste samples to obtain results for a number of RCRA regulated metals without the need to utilize a separate sample preparation method (EPA SW-846 method 7471A) specific only for Hg

A maximum likelihood estimate for two-variable fractal surface

The fractal dimension estimate for two-variable fractional Brownian motion using the maximum likelihood estimate (MLE) is developed. We formulate a model to describe the two-variable fractional Brownian motion, then derive the likelihood function for that model and estimate the fractal dimension by maximizing the likelihood function. We then compare the MLE with the box-dimension estimation metho