Prototype solar power satellite options

The choice of options for the prototype solar power satellite is addressed relative to risk and cost. Emphasis is placed on the reduction of the risk of failure. Risk is the program cost multiplied by the reduction in probability of program success due to the risky action. Four classes of risk are identified. It is suggested that prototyping would reduce the technical risk as well as reduce the effects of the other three types of risk by allowing them to be quantified earlier. Prototype demonstration requirements addressed include electromagnetic power link feasibility demonstration, component integration verification, construction technology verification, and cost performance verification. Specific prototype requirements are listed and prototyping options are given in tabular form

High-power microwave optics for flexible power transmission systems

A large concave microwave mirror near the transmitter can magnify the apparent size of the Earth as seen from a phased array, and vice versa, permitting a small phased array to be coupled to a small rectenna while preserving the transmission efficiency (the reflection loss is slight) and peak power densities characteristic of the reference system. This augmentation of the phased array aperture with a large mirror gives the system greater resolution (in the optical sense), and opens new degrees of freedom in SPS design. The consequences of such an approach for a prototype satellite were explored. Its consequences for a mature SPS are discussed

Modified Reference SPS with Solid State Transmitting Antenna

The development of solid state microwave power amplifiers for a solar power satellite transmitting antenna is discussed. State-of-the-art power-added efficiency, gain, and single device power of various microwave solid state devices are compared. The GaAs field effect transistors and the Si-bipolar transistors appear potentially feasible for solar power satellite use. The integration of solid state devices into antenna array elements is examined and issues concerning antenna integration and consequent satellite configurations are examined

SPS phase control studies

To properly point and form the satellite microwave power beam, the outputs of the power amplifiers in the transmitting array must be phased in a specific and coherent fashion. A retrodirective CW phase conjugating system using a spread spectrum uplink signal and a reference phase signal that is distributed via fiber optics, was selected as the control system for SPS. The design details are presented and applications of the system are discussed

Characterization of reflected light from the space power system

Sunlight reflected off large space structures is examined. To assure that this illumination does not exceed the irradiance tolerances of the eye, reflections from these satellites must be controlled by vehicle orientation and surface specifications. The components of various space power system vehicles to determine the reflectances which will significantly contribute to the ground illumination are evaluated. Calculations of reflected solar intensity from various satellite system elements requires description of the elements and of the geometry potential reflectance paths. Surface intensity and the conditions under which it will illuminate a portion of the Earth are also determined

An integrated SDN architecture for application driven networking

The target of our effort is the definition of a dynamic network architecture meeting the requirements of applications competing for reliable high performance network resources. These applications have different requirements regarding reli- ability, bandwidth, latency, predictability, quality, reliable lead time and allocatability. At a designated instance in time a virtual network has to be defined automatically for a limited period of time, based on an existing physical network infrastructure, which implements the requirements of an application. We suggest an integrated Software Defined Network (SDN) architecture providing highly customizable functionalities required for efficient data transfer. It consists of a service interface towards the application and an open network interface towards the physical infrastruc- ture. Control and forwarding plane are separated for better scalability. This type of architecture allows to negotiate the reser- vation of network resources involving multiple applications with different requirement profiles within multi-domain environments

The role of orienting in vibrissal touch sensing

Rodents, such as rats and mice, are strongly tactile animals who explore the environment with their long mobile facial whiskers, or macrovibrissae, and orient to explore objects further with their shorter, more densely packed, microvibrissae. Although whisker motion (whisking) has been extensively studied, less is known about how rodents orient their vibrissal system to investigate unexpected stimuli. We describe two studies that address this question. In the first we seek to characterize how adult rats orient toward unexpected macrovibrissal contacts with objects and examine the microvibrissal exploration behavior following such contacts. We show that rats orient to the nearest macrovibrissal contact on an unexpected object, progressively homing in on the nearest contact point on the object in each subsequent whisk. Following contact, rats “dab” against the object with their microvibrissae at an average rate of approximately 8 Hz, which suggests synchronization of microvibrissal dabbing with macrovibrissal motion, and an amplitude of 5 mm. In study two, we examine the role of orienting to tactile contacts in developing rat pups for maintaining aggregations (huddles). We show that young pups are able to orient to contacts with nearby conspecifics before their eyes open implying an important role for the macrovibrissae, which are present from birth, in maintaining contact with conspecifics. Overall, these data suggest that orienting to tactile cues, detected by the vibrissal system, plays a crucial role throughout the life of a rat

The role of control beliefs in predicting physical activity among Active Living Every Day participants with arthritis

Physical activity promotion constitutes an important public health approach to managing arthritis, the leading cause of disability in the US. Many people with arthritis have good outcomes with lifestyle physical activity. However, we do not know why some fare better than others. Perceived control over exercise ability and outcomes have predicted physical activity in other studies, but less is known about how these beliefs relate to physical activity within the context of arthritis. I explored the role of these factors in predicting physical activity among participants with arthritis in Active Living Every Day (ALED) , a theory-informed lifestyle physical activity program originally designed for people without arthritis. I analyzed baseline and post-test data of the intervention group from an evaluation of ALED for people with arthritis. Candidate predictors were depressive symptoms, physical symptoms, and control beliefs (helplessness, arthritis and exercise self-efficacy, and exercise outcome expectations). Hierarchical linear regression was used to examine baseline predictors of post-intervention physical activity and function. A second analytic approach used multiple mediation to test relationships posited in Social Cognitive Theory. I examined whether physical and depressive symptoms affected physical activity via exercise and arthritis symptom self-efficacy and whether outcome expectations mediated between these types of self-efficacy and physical activity. The final analyses replicated these mediation analyses but with only post-test measures of efficacy and outcome expectations. The final sample consisted of 143 intervention participants. Their mean age was 68 years, and the majority were female (86%) and white (75%). Slightly more than half (55%) had above a high school education. Control beliefs emerged as influential beyond arthritis symptoms in both the hierarchical regression and mediation analyses. Post-test outcome expectations also significantly mediated the relationship between baseline self-efficacy and post-test physical activity. Higher education predicted more physical activity. Depressive symptoms did not predict physical activity. Because control beliefs at both the beginning and end of the intervention were important predictors of physical activity outcomes, even more attention needs to be given to them in interventions directed at people with arthritis. Lifestyle physical activity interventions for people with arthritis might be more effective with greater attention given to cognitive behavioral techniques for both exercise and symptom management. Additionally, program material that meets needs of those with less formal education could yield better outcomes for more participants

Response to ?A Madden-Julian Oscillation Event Realistically Simulated by a Global Cloud-Resolving Model?

I agree with the authors that forecasting the Madden-Julian Oscillation (MJO) in a high resolution global model is important for numerous reasons, including improved weather forecast skill beyond 10 days, and resolving small scale features embedded in the MJO that coarse resolution ({approx}100-300km horizontal grid spacing) climate models do not (e.g., tropical cyclones). Unfortunately, the authors promote the (incorrect) overall impression that coarse resolution climate models cannot simulate the MJO by (a) only discussing aspects of works that indicate the poor ability of coarse resolution climate models to simulate the MJO, and (b) by promoting the use of higher resolution models, and the use of embedded two-dimensional cloud resolving models embedded in coarse resolution climate models as the principal methods for realistically representing the MJO because of the difficulty of coarse resolution models 'to estimate the vertical redistribution of heat and moisture by unresolved convective clouds'. Regarding items (a) and (b), I have co-authored two of the works cited by Miura et al. that bemoan the poor ability of coarse resolution climate models to simulate the MJO, and indeed simulating the MJO in coarse resolution climate models is a grand challenge. However, I would like to draw to their attention to work that has demonstrated that two different coarse resolution climate models, using conventional parameterizations of convection and clouds, can represent the MJO with high fidelity. In the later study, where more complete model diagnostics were available, important aspects of the MJO that were realistically represented included the relationship between convection and low-level moisture convergence, surface fluxes, the vertical structure of winds and divergence, and important air-sea interactions. Additionally, regarding item (b), convection is certainly of central importance in representing the MJO, but it is the interaction of convection (parameterized or otherwise) with other aspects of the model physics that is important. Thus, it is the implementation of the full physics package that is relevant, not simply the manner in which convection is represented. The issue at hand is to determine what aspects of the physics present in the high resolution (and embedded 2-dimensional cloud resolving model) simulations are essential for incorporation into coarse resolution climate model parameterizations in order for them to adequately represent the MJO. In the foreseeable future, models used for climate and climate change studies will continue to require convective parameterization in order to produce simulations that span decadal to centennial time scales to estimate the impact of anthropogenic influences on the statistics of weather variability and extremes. As such, intercomparison across different classes of modeling is essential to better understand the physics relevant to the climate system