Diesel Fuel Consumption During Field Operations

Direct energy expenses (diesel, gasoline, propane, electricity) total more than $1 billion annually for Iowa’s farmers. Farm management techniques such as adjusting tractor gear and throttle settings, reducing tillage depths, and monitoring tractor tire inflation pressures can reduce diesel fuel consumption for row crop production. This study is being conducted over multiple years to measure the effects of energy management techniques on tractor fuel consumption during spring and fall field operations

Energy management on Iowa farms

Iowa agriculture spends about one billion dollars annually on the purchase of diesel fuel, electricity, propane, gasoline and natural gas. The actual amount fluctuates with the rise and fall of energy prices

Conductivity in a symmetry broken phase: Spinless fermions with 1/d1/d corrections

The dynamic conductivity $\sigma(\omega)$ of strongly correlated electrons in a symmetry broken phase is investigated in the present work. The model considered consists of spinless fermions with repulsive interaction on a simple cubic lattice. The investigated symmetry broken phase is the charge density wave (CDW) with wave vector $Q=(\pi,\pi,\pi)^\dagger$ which occurs at half-filling. The calculations are based on the high dimensional approach, i.e. an expansion in the inverse dimension $1/d$ is used. The finite dimensionality is accounted for by the inclusion of linear terms in $1/d$ and the true finite dimensional DOS. Special care is paid to the setup of a conserving approximation in the sense of Baym/Kadanoff without inconsistencies. The resulting Bethe-Salpeter equation is solved for the dynamic conductivity in the non symmetry broken and in the symmetry broken phase (AB-CDW). The dc-conductivity is reduced drastically in the CDW. Yet it does not vanish in the limit $T \to 0$ due to a subtle cancellation of diverging mobility and vanishing DOS. In the dynamic conductivity $\sigma(\omega)$ the energy gap induced by the symmetry breaking is clearly discernible. In addition, the vertex corrections of order $1/d$ lead to an excitonic resonance lying within the gap.Comment: 23 pages, 19 figures included with psfig, Revtex; Physical Review B15, in press (October/November 1996) depending on the printer/screen driver, it might be necessary to comment out figures 3,4,5,10,11,12,19 and have them printed separatel

Self-propelled particles with fluctuating speed and direction of motion

We study general aspects of active motion with fluctuations in the speed and the direction of motion in two dimensions. We consider the case in which fluctuations in the speed are not correlated to fluctuations in the direction of motion, and assume that both processes can be described by independent characteristic time-scales. We show the occurrence of a complex transient that can exhibit a series of alternating regimes of motion, for two different angular dynamics which correspond to persistent and directed random walks. We also show additive corrections to the diffusion coefficient. The characteristic time-scales are also exposed in the velocity autocorrelation, which is a sum of exponential forms.Comment: to appear in Phys. Rev. Let

Energy costs for grain drying and field operations

Iowa spends about one billion dollars annually on the purchase of diesel fuel, electricity, propane, gasoline, and natural gas. Specifically, Iowa spent more than one billion dollars on energy in 2012 including $866,990,000 for gasoline, fuels, and oils (primarily diesel fuel and LP) and$329,138,000 for utilities (primarily electricity) according to the USDA Agricultural Census (USDA, 2014). Correspondingly, farm enterprises nationwide spent $16,573,188,000 for gasoline, fuels, and oils and$8,261,978,000 for utilities in 2012. Purchases of diesel fuel, liquid propane (LP), and natural gas are included in gasoline, fuels, and oils. Electricity, telephone charges, internet fees, and purchased water are included in utilities costs