A Method for Balloon Trajectory Control

This presentation was part of the session : Short CoursesSixth International Planetary Probe WorkshopA balloon trajectory control system is discussed that is under development for use on NASA's Ultra Long Duration Balloon Project. The trajectory control system exploits the natural wind field variation with altitude to generate passive lateral control forces on a balloon using a tether-deployed aerodynamic surface below the balloon. A lifting device, such as a wing on end, is suspended on a tether well beneath the balloon to take advantage of this variation in wind velocity with altitude. The wing generates a horizontal lift force that can be directed over a wide range of angles. This force, transmitted to the balloon by a tether, alters the balloon's path providing a bias velocity of a few meters per second to the balloon drift rate. The trajectory control system enables the balloon to avoid hazards, reach targets, steer around avoidance countries and select convenient landing zones. No longer will balloons be totally at the mercy of the winds. Global Aerospace Corporation tests in April 1999 of a dynamically scaled model of the trajectory control system were carried out in ground level winds up to 15 m/s. The size of the scale model was designed to simulate the behavior of the full scale trajectory control system operating at 20 km altitude. The model confirmed many aspects of trajectory control system performance and the results will be incorporated into future development.NASA Small Business Innovation Research (SBIR) Progra

Amplified fragment length polymorphisms (AFLPs) analysis of species of Solanum section Solanum (Solanaceae) from Uganda

The taxonomy of species belonging to Solanum section Solanum (sometimes referred to as the Solanum nigrum complex or black nightshades) is known to be difficult and has resulted in extensive synonymy. Yet, these species play a significant role in nutrition and food security, especially in developing countries. The amplified fragment length polymorphisms (AFLPs) technique was used to assess the genetic relationships among 107 accessions representing eight species of the section Solanum and to obtain new insight into the taxonomic status of the S. nigrum complex. Four primer combinations yielded 510 AFLP bands, only 29 of which were monomorphic. Neighbor-joining and principal coordinates analyses were performed. The AFLP data only partially correlated with earlier classifications based on morphology. We have been able to confirm the presence of only 5 out of eight species of this complex previously recognized from Uganda, that is, Solanum americanum, Solanum scabrum, Solanum hirsutum, Solanum florulentum/Solanum tarderemotum and Solanum villosum. In addition, S. villosum did not separate in accordance with previous subspecific ranks. It is likely that neither Solanum grossidentatum, S. nigrum nor Solanum sarrachoides occurred in Uganda. Also, there was no correlation between geographic localities for the Ugandan material and the AFLP results, indicating that most of the studied species are introduced.Key words: Amplified fragment length polymorphisms (AFLPs), Solanum nigum complex, Africa, genetic variation, taxonomy, Uganda

Combining Molecular Dynamics with Lattice-Boltzmann: A Hybrid Method for the Simulation of (Charged) Colloidal Systems

We present a hybrid method for the simulation of colloidal systems, that combines molecular dynamics (MD) with the Lattice-Boltzmann (LB) scheme. The LB method is used as a model for the solvent in order to take into account the hydrodynamic mass and momentum transport through the solvent. The colloidal particles are propagated via MD and they are coupled to the LB fluid by viscous forces. With respect to the LB fluid, the colloids are represented by uniformly distributed points on a sphere. Each such point (with a velocity V(r) at any off-lattice position r is interacting with the neighboring eight LB nodes by a frictional force F=\xi_0(V(r)-u(r)) with \xi_0 being a friction force and u(r) being the velocity of the fluid at the position r. Thermal fluctuations are introduced in the framework of fluctuating hydrodynamics. This coupling scheme has been proposed recently for polymer systems by Ahlrichs and D"unweg [J. Chem. Phys. 111, 8225 (1999)]. We investigate several properties of a single colloidal particle in a LB fluid, namely the effective Stokes friction and long time tails in the autocorrelation functions for the translational and rotational velocity. Moreover, a charged colloidal system is considered consisting of a macroion, counterions and coions that are coupled to a LB fluid. We study the behavior of the ions in a constant electric field. In particular, an estimate of the effective charge of the macroion is yielded from the number of counterions that move with the macroion in the direction of the electric field.Comment: 37 pages, 12 figure

Exploring Planets with Directed Aerial Robot Explorers

Global Aerospace Corporation (GAC) is developing a revolutionary system architecture for exploration of planetary atmospheres and surfaces from atmospheric altitudes. The work is supported by the NASA Institute for Advanced Concepts (NIAC). The innovative system architecture relies upon the use of Directed Aerial Robot Explorers (DAREs), which essentially are long-duration-flight autonomous balloons with trajectory control capabilities that can deploy swarms of miniature probes over multiple target areas. Balloon guidance capabilities will offer unprecedented opportunities in high-resolution, targeted observations of both atmospheric and surface phenomena. Multifunctional microprobes will be deployed from the balloons once over the target areas, and perform a multitude of functions, such as atmospheric profiling or surface exploration, relaying data back to the balloons or an orbiter. This architecture will enable low-cost, low-energy, long-term global exploration of planetary atmospheres and surfaces. This paper focuses on a conceptual analysis of the DARE architecture capabilities and science applications for Venus, Titan and Jupiter. Preliminary simulations with simplified atmospheric models show that a relatively small trajectory control wing can enable global coverage of the atmospheres of Venus and Titan by a single balloon over a 100-day mission. This presents unique opportunities for global in situ sampling of the atmospheric composition and dynamics, atmospheric profiling over multiple sites with small dropsondes and targeted deployment of surface microprobes. At Jupiter, path guidance capabilities of the DARE platforms permits targeting localized regions of interest, such as "hot spots" or the Great Red Spot. A single DARE platform at Jupiter can sample major types of the atmospheric flows (zones and belts) over a 100-day mission. Observations by deployable probes would reveal if the differences exist in radiative, dynamic and compositional environments at these sites

Quantifying the Environmental Impacts of Cookstove Transitions: A Societal Exergy Analysis Based Model of Energy Consumption and Forest Stocks in Honduras

Unsustainable consumption of biofuels contributes to deforestation and climate change, while household air pollution from burning solid biofuels in homes results in millions of premature deaths globally every year. Honduras, like many low and medium Human Development Index countries, depends on primary solid biofuels for more than 30% of its primary energy supply (as of 2013). We conducted a societal exergy analysis and developed a forest stock model for Honduras for 1971–2013 and used the results to model an energy transition from traditional wood stoves to either improved efficiency wood cookstoves or modern fuel cookstoves (using Electricity or Liquefied petroleum gas) over the period 2013–2050. The exergy analysis and forest model enabled quantification of the environmental tradeoffs between the improved efficiency and fuel switching scenarios. We find that the continued reliance on wood within both the existing and improved wood cookstove scenarios would exhaust forest stocks by 2050, though improved efficiency could reduce national greenhouse gas emissions. Modern fuel cookstoves would reduce household air pollution, emissions, and deforestation. However, the best alternative to successfully reduce household air pollution, GHG emissions, and deforestation is a rapid switch to electric stoves with significant investment in renewable-based electricity

Gravitational instability of simply rotating AdS black holes in higher dimensions

We study the stability of AdS black hole holes rotating in a single two plane for tensor-type gravitational perturbations in $D > 6$ space-time dimensions. First, by an analytic method, we show that there exists no unstable mode when the magnitude $a$ of the angular momentum is smaller than $r_h^2/R$ where $r_h$ is the horizon radius, and $R$ is the AdS curvature radius. Then, by numerical calculations of quasinormal modes, using the separability of the relevant perturbation equations, we show that an instability occurs for rapidly rotating black holes with $a>r_h^2/R$, although the growth rate is tiny (of order $10^{-12}$ of the inverse horizon radius). We give numerical evidences indicating that this instability is caused by superradiance.Comment: 17 page

Борьба с биообрастанием природных и сточных вод с использованием энергетических воздействий

Данная работа посвящена анализу методов очистки воды для борьбы с биологическим обрастанием технологического оборудования. Рассмотрены различные способы борьбы с биологическим обрастанием, в том числе: реагентные, безреагентные и электрические. Сформирована концепция применения способа борьбы с биологическим обрастанием технологического оборудования путем электрической обработки теплоносителя. Приведена схема установки, таблица результатов и диаграмма.This work is devoted to the analysis of methods of water purification for fight against biological fouling of processing equipment. Various ways of fight against biological fouling are considered, including: reagent, reagentless and electric. The concept of application of a way of fight against biological fouling of processing equipment by electric processing of the heat carrier is created. The scheme of installation, the table of results and the chart is provided

Mechanical characteristics of the hypereutectic silumin processed by ionelectron-plasma modification

In this paper, the possibility of modifying the surface of a hypereutectic silumin (Al-(18-24) wt.%Si) is shown. Modification of the samples was carried out in two stages. At the first stage, a "film (Zr-5% Ti-5% Cu) / (Al- (18-24) wt.% Si) film system was formed by an ion-plasma method with an arc-sputtering of a Zr-5% Ti-5 cathode % Cu in the "TRIO" installation (IHCE SB RAS). In the second stage, the surface layer of the silumin of the hypereutectic composition was doped by melting the "film-substrate" system with an intense pulsed electron beam at the "SOLO" installation