The Viability of Harvesting Corn Cobs and Stover for Biofuel Production in North Dakota

This study examines the impact of stochastic harvest field time, corn cob and stover harvest technologies, increases in farm size, and alternative tillage practices on profit maximizing potential of corn cob and stover collection in North Dakota. Using three mathematical programming models, we analyze farmers’ harvest activities under 1) corn grain only harvest option, 2) simultaneous corn grain and cob harvest(one-pass) option 3) separate corn grain and stover harvest (two-pass) option. Under the first corn grain only option, farmers are able to complete harvesting corn grain and achieve maximum net income in a fairly short amount of time with existing combine technology. However, under the simultaneous corn grain and cob one-pass harvest option, our findings indicate that farmers generate lower net income as compared to the net income of corn grain only harvest option. This is due to the slowdown in combine harvest capacity as a consequence of attaching cob harvester to the back of combine. Under the third option of a two-pass harvest system, time allocation is the main challenge and our evidence shows that with limited harvest field time available, farmers find it optimal to allocate most of their time harvesting grain, and then proceed to bale stover if time permits at the end of harvest season. As farm size increases, farmers are especially challenged in finding time to harvest both corn grain and cobs/stover. We show that a small decrease in corn yield due to changes in tillage practice can result in a large decline in the net profit of harvesting corn grain and cobs/stover.Cob, Stover, harvest field time, optimization, farm size, tillage, Crop Production/Industries, Production Economics,

Apollo experience report: A use of network simulation techniques in the design of the Apollo lunar surface experiments package support system

A case study of data-communications network modeling and simulation is presented. The applicability of simulation techniques in early system design phases is demonstrated, and the ease with which model parameters can be changed and comprehensive statistics gathered is shown. The discussion of the model design and application also yields an insight into the design and implementation of the Apollo lunar surface experiments package ground-support system

Station-keeping guidance

The station-keeping guidance system is described, which is designed to automatically keep one orbiting vehicle within a prescribed zone fixed with respect to another orbiting vehicle. The active vehicle, i.e. the one performing the station-keeping maneuvers, is referred to as the shuttle. The other passive orbiting vehicle is denoted as the workshop. The passive vehicle is assumed to be in a low-eccentricity near-earth orbit. The primary navigation sensor considered is a gimballed tracking radar located on board the shuttle. It provides data on relative range and range rate between the two vehicles. Also measured are the shaft and trunnion axes gimbal angles. An inertial measurement unit (IMU) is provided on board the orbiter. The IMU is used at all times to provide an attitude reference for the vehicle. The IMU accelerometers are used periodically to monitor the velocity-correction burns applied to the shuttle during the station-keeping mode. The guidance system is capable of station-keeping the shuttle in any arbitrary position with respect to the workshop by periodically applying velocity-correction pulses to the shuttle

Nondiffusive suprathermal ion transport in simple magnetized toroidal plasmas

We investigate suprathermal ion dynamics in simple magnetized toroidal plasmas in the pres- ence of electrostatic turbulence driven by the ideal interchange instability. Turbulent fields from fluid simulations are used in the non-relativistic equation of ion motion to compute suprathermal tracer ion trajectories. Suprathermal ion dispersion starts with a brief ballistic phase, during which particles do not interact with the plasma, followed by a turbulence interaction phase. In this one simple system, we observe the entire spectrum of suprathermal ion dynamics, from subdiffusion to superdiffusion, depending on beam energy and turbulence amplitude. We estimate the duration of the ballistic phase and identify basic mechanisms during the interaction phase that determine the character of suprathermal ion dispersion upon the beam energy and turbulence fluctuation amplitude.Comment: 5 pages, 3 figures, accepted in PR

Fractional diffusion emulates a human mobility network during a simulated disease outbreak

From footpaths to flight routes, human mobility networks facilitate the spread of communicable diseases. Control and elimination efforts depend on characterizing these networks in terms of connections and flux rates of individuals between contact nodes. In some cases, transport can be parameterized with gravity-type models or approximated by a diffusive random walk. As a alternative, we have isolated intranational commercial air traffic as a case study for the utility of non-diffusive, heavy-tailed transport models. We implemented new stochastic simulations of a prototypical influenza-like infection, focusing on the dense, highly-connected United States air travel network. We show that mobility on this network can be described mainly by a power law, in agreement with previous studies. Remarkably, we find that the global evolution of an outbreak on this network is accurately reproduced by a two-parameter space-fractional diffusion equation, such that those parameters are determined by the air travel network.Comment: 26 pages, 4 figure

Laboratory simulations of comet surfaces

The geometric albedos of frozen mixtures consisting of colloidal silica and carbon black mixed with water have been measured over the wavelength range of 400 to 800 nm to compare with recent observations of Comet Halley. Data were obtained as a function of sample temperature, scattering angle, and wavelength as the frozen samples warmed to 0 C in vacuum. Scattering from water ice, flat black paint, and Kodak white reflectance paint were also measured. Lab simulations show that the change in albedo of the samples show that sublimation of the water from the sample surface can have a major effect on the albedo of a particle/ice sample in the visible. Such processing may have a marked effect on the visible albedo of comet surfaces as well

Did Earth-approaching asteroids 3551, 3908, or 4055 produce meteorites?

Orbital integrations show that Amor asteroid 3908 could have ejected one out of four plausible groups of meteorite producing fireballs during a collision in the asteroid belt. It was suggested by others that such a collision may also have split asteroids 3551 and 3908. A member of this group of fireballs is listed as one of the better possibilities for recovery

Color separate singlets in e+e−e^+e^- annihilation

We use the method of color effective Hamiltonian to study the properties of states in which a gluonic subsystem forms a color singlet, and we will study the possibility that such a subsystem hadronizes as a separate unit. A parton system can normally be subdivided into singlet subsystems in many different ways, and one problem arises from the fact that the corresponding states are not orthogonal. We show that if only contributions of order $1/N_c^2$ are included, the problem is greatly simplified. Only a very limited number of states are possible, and we present an orthogonalization procedure for these states. The result is simple and intuitive and could give an estimate of the possibility to produce color separated gluonic subsystems, if no dynamical effects are important. We also study with a simple MC the possibility that configurations which correspond to "short strings" are dynamically favored. The advantage of our approach over more elaborate models is its simplicity, which makes it easier to estimate color reconnection effects in reactions which are more complicated than the relatively simple $e^+e^-$ annihilation.Comment: Revtex, 24 pages, 7 figures; Compared to the previous version, 1 new figure is added and Monte-Carlo results are re-analyzed, as suggested by the referee; To appear in Phys. Rev.