Trends in the incidence of rain height and the effects on global satellite telecommunications

Satellite communications using millimetre waves, in Ka band and above, experience significant fading by rain. Strong attenuation is experienced between the ground station and a level known as the rain height, in ITU-R recommendations assumed to be 360 m above the zero-degree isotherm (ZDI). This paper examines NOAA NCEP/NCAR Reanalysis 1 data to identify changes in the ZDI height over the last 30 years. Near the equator and the poles the ZDI height has been approximately stable over this period. However, in mid-latitudes, different regions show trends of increasing or decreasing ZDI height. Over the economically important regions of North America, China and Western Europe, the ZDI height has shown an increasing trend with peak rates in the range of 8 to 10 metres per year. Given a twenty-year life-time of a satellite system, this could lead to a 10 to 20% increase in fade intensity from a similar rain event. The effect will be compounded by increasing trends in the incidence of heavy rain recently identified in UK data. These trends will need to be considered when designing new systems

Stability for Receding-horizon Stochastic Model Predictive Control

A stochastic model predictive control (SMPC) approach is presented for discrete-time linear systems with arbitrary time-invariant probabilistic uncertainties and additive Gaussian process noise. Closed-loop stability of the SMPC approach is established by appropriate selection of the cost function. Polynomial chaos is used for uncertainty propagation through system dynamics. The performance of the SMPC approach is demonstrated using the Van de Vusse reactions.Comment: American Control Conference (ACC) 201

The Impact of State Fiscal Policy on States\u27 Resilience Entering the Great Recession

The U.S. economy entered the Great Recession in December 2007 and exited in June 2009. This national statistic obscures a wealth of state-level data shedding light on the policies and conditions that helped some states withstand that recessionary shock for a time. In this study, we used that state-level data in a parametric regression model, known as survival analysis, to estimate the effects that a state’s fiscal policy had on the timing of its entry into the Great Recession. Consistent with earlier, more general, studies focusing on economic growth, we found that taxes have the potential to hasten the start of a state’s recession, while expenditures could defer that event. However, not all types of taxes and expenditures were equivalent in terms of their effect on recessionary timing. Most notably, our results showed that corporate income taxes had a different timing effect than sales, property, and individual income taxes. In addition, although total expenditures tended to delay the Great Recession’s onset, relatively few individual expenditure types had a statistically-significant impact on recessionary timing. Overall, our results suggest that, while taxes likely increase a state’s recessionary risk and expenditures likely decrease it, that narrative is an oversimplification of the complex role played by fiscal policy in determining a state\u27s ability to resist a negative economic shock like the Great Recession

Readdressing the Fertilizer Problem

The production literature has shown that inputs such as fertilizer can be defined as risk-increasing. However, farmers also consistently overapply nitrogen. A model of optimal input use under uncertainty is used to address this paradox. Using experimental data, a stochastic production relationship between yield and soil nitrate is estimated. Numerical results show that input uncertainty may cause farmers to overapply nitrogen. Survey data suggest that farmers are risk averse, but prefer small chances of high yields compared to small chances of crop failures when expected yields are equivalent. Furthermore, yield risk and yield variability are not equivalent.corn, nitrogen fertilizer, risk-increasing, yield risk, Crop Production/Industries,

Postshutdown cooling requirements of tungsten water-moderated nuclear rocket

Postshutdown cooling requirements of tungsten water moderated nuclear rocket engine

A rain height model to predict fading due to wet snow on terrestrial links

Recommendation ITU‐R P.530‐13 provides an internationally recognized prediction model for the fading due to wet snow on low‐elevation, terrestrial microwave links. An important parameter in this model is the altitude difference between the link and the rain height. The top of rain events is usually assumed to be 360 m above the zero‐degreeisotherm (ZDI). Above this height, hydrometeors are ice with low specific attenuation. Below this level, melting ice particles produce a specific attenuation up to 4 times that of the associated rain rate. A previous paper identified increasing ZDI height trends across northern Europe, North America and central Asia with slopes up to 10 m/yr. This paper examines NOAA National Centers for Environmental Prediction-National Center for Atmospheric Research Reanalysis 1 data to identify global distributions of ZDI height around mean levels that increase linearly over time. The average annual distribution of ZDI heights relative to the annual mean are calculated for each NOAA Reanalysis grid square and skew normal distributions are fitted. These are compared to models in Recommendation ITU‐R P.530‐13 and Recommendation ITU‐R 452‐14. The effects of ZDI trends and the calculated skew normal distributions are illustrated using calculated trends in fading due to wet snow for two notional 38 GHz links in Edinburgh. A slow decrease in the incidence of fading due to wet snow is predicted over most of Europe. However, some links could experience increases where warming has increased the wetness of snow

The influence of three short-term weight loss interventions on self-efficacy, decisional balance, and processes of change in obese adults

Motivational and psychosocial outcomes have not been reported in behavioral weight loss programs utilizing the SenseWear Pro armband (SWA) and motivational interviewing; making it difficult to identify motivational components that may be related to weight loss. The Transtheoretical Model (TTM) is one model used to help explain motivation and behavior change through the constructs of decisional balance (DB), diet and physical activity self-efficacy (SE), and cognitive and behavioral processes of change (C-POC, B-POC). The purpose of this study was to assess the changes in TTM constructs of DB, SE, and both C-POC and B-POC in a randomized trial evaluating three different weight loss interventions in obese adults. Seventy-eight subjects (32 males and 46 females) completed one of three 8-week weight loss interventions with guidance from a health coach and the utilization of motivational interviewing techniques. Group 1 (n = 26) received a behaviorally guided weight loss program (GWLP), Group 2 (n = 26) received a self-monitoring tool called the SenseWear Pro Armband (SWA) with Weight management system (WMS) and Group 3 (n = 26) received both programming options (GWLP + SWA). Weight change and changes in TTM constructs of SE, DB (pros vs. cons), and C-POC and B-POC were assessed at baseline and at the completion of the intervention. Changes in variables across time and condition were assessed using multivariate ANOVAs and the magnitude of effects were reported using effect sizes. All interventions produced significant weight loss, with no significant differences between groups. Significant changes in TTM constructs were observed over time and some differences were evident between groups. Large effect sizes were found for improvements in SE in groups that received the GWLP (Groups 1 and 3), while slight improvements were seen in the SWA group (Group 2). Decisional balance improved significantly (p \u3c 0.05) in the combined GWLP + SWA intervention (Group 3). Significant improvements (p \u3c 0.001) over time were evident for specific B-POC: counterconditioning, interpersonal systems control, reinforcement management, self-liberation, and stimulus control. The results of this study support previous evidence showing improvements in self-efficacy directly after an active intervention, but warrants further examination for identifying which processes of change are influenced via self-monitoring techniques and the use of motivational interviewing techniques on motivational and behavioral outcomes. Longer-term studies are needed to determine if these factors may influence maintenance of weight loss

Regulation through Intimidation: Congressional Hearings and Political Pressure on America\u27s Entertainment Media

This paper explores how Congress has shaped and limited the content of films, comic books, popular music, and television over the past century. Specifically, this report focuses on the path to self-regulation and industry-wide codes for these four media, and how government used pressure and influence to spur the adoption of standards