Technique for predicting high-frequency stability characteristics of gaseous-propellant combustors

A technique for predicting the stability characteristics of a gaseous-propellant rocket combustion system is developed based on a model that assumes coupling between the flow through the injector and the oscillating chamber pressure. The theoretical model uses a lumped parameter approach for the flow elements in the injection system plus wave dynamics in the combustion chamber. The injector flow oscillations are coupled to the chamber pressure oscillations with a delay time. Frequency and decay (or growth) rates are calculated for various combustor design and operating parameters to demonstrate the influence of various parameters on stability. Changes in oxidizer design parameters had a much larger influence on stability than a similar change in fuel parameters. A complete description of the computer program used to make these calculations is given in an appendix

The Distribution of Rents in Supply Chain Industries: The Case of High Oil Corn

Value-enhanced crops (VEC's) have been the focus of "second-generation" genetically modified (GM) crops. The market power granted by intellectual property rights (IPR) and the use of contractual arrangements in VEC gene and seed production have fostered a move toward tightly-aligned supply chain industries. This paper suggests and tests an analytical methodology for examining a number of issues in tightly-aligned supply chain industries: (1) the distributions of potential monopolistic and monopsonistic rents, (2) choices of licensing intellectual property versus in-house seed production and distribution (3) implications of alternative marketing strategies and elasticities of demand on the magnitudes of rents, and (4) determining impacts on different stages within the supply chain and on substitute commodities. The high-oil corn industry is used as a case study.equilibrium displacement, high-oil corn, mathematical programming, value-enhanced crops, Crop Production/Industries, Industrial Organization,

Non-adiabatically driven electron in quantum wire with spin-orbit interaction

An exact solution is derived for the wave function of an electron in a semiconductor quantum wire with spin-orbit interaction and driven by external time dependent harmonic confining potential. The formalism allows analytical expressions for various quantities to be derived, such as spin and pseudo-spin rotations, energy and occupation probabilities for excited states. It is demonstrated how perfect spin and pseudo-spin flips can be achieved at high frequencies of order \omega, the confining potential level spacing. By an appropriately chosen driving term, spin manipulation can be exactly performed far into the non-adiabatic regime. Implications for spin-polarised emission and spin-dependent transport are also discussed.Comment: 11 pages, 3 figure

The Economic Feasibility of Producing Pasture Poultry for Limited Resource Farmers in Southeastern North Carolina

This study examines the economic feasibility of two pasture poultry production operations (pasture pen and net range) by limited resource farmers (LRFs) using the Net Present Value (NPV) method of analysis. Results of the NPV method illustrated unacceptable investments for both production operations.Alternative Enterprises, Agricultural Prosperity, Pasture Poultry Production, Limited Resource Farming, Farm Management, Land Economics/Use,

Search for Σ(5)(0), N(5)(0), and Θ++ Pentaquark States

A high-resolution (σinstr.=1.5 MeV) search for narrow states (ΓMeV) with masses of Mx≈1500–1850 MeV in ep→e′K+X,e′K-X, and e′π+X electroproduction at small angles and low Q2 was performed. These states would be candidate partner states of the reported Θ+(1540) pentaquark. No statistically significant signal was observed in any of the channels at 90% C.L. Upper limits on forward production were determined to be between 0.8% and 4.9% of the Λ(1520) production cross section, depending on the channel and the assumed mass and width of the state

Multi-year Measurements of Black Carbon Aerosol over Barrow and Ny-Alesund in the Arctic

第6回極域科学シンポジウム分野横断セッション：[IA] 急変する北極気候システム及びその全球的な影響の総合的解明―GRENE北極気候変動研究事業研究成果報告2015―11月19日（木）　国立極地研究所１階交流アトリウ

Managing an annual legume green manure crop for fallow replacement in southwestern Saskatchewan

Non-Peer ReviewedSome scientists have suggested that in the Brown soil zone an annual legume green manure crop (GM) could be used as a partial-fallow replacement to protect the soil against erosion and increase its N fertility, particularly when combined with a snow trapping technique to replenish soil water used by the legume. We assessed this possibility by comparing yields, N economy, water use efficiency, and economic returns of hard red spring wheat (W) grown in rotation with Indianhead black lentil (i.e., GM-W-W) vs. that obtained in a F-W-W system. Further, we assessed whether a change in management of the GM crop (i.e., moving to earlier seeding and earlier turn-down) was advantageous to the overall performance of this practice. The study was conducted over 12 years (1988-99) on a loam soil at Swift Current, SK. (wheat stubble was left tall to trap snow, tillage was kept to a minimum, and the wheat was fertilized based on soil tests). When examined after 6 years, the results suggested that by waiting for full bloom of the legume (usually late July or early August) to maximize N2 fixation, soil water was being depleted to the detriment of yields of the following wheat crop. However, the change in management of the GM crop since 1994 has resulted in wheat yields following GM equalling those after fallow. It also produced a significant increase (after one rotation cycle) in grain protein and N yields of aboveground parts of wheat in the GM-W-W compared to the F-W-W system, and lead to a gradual decrease in fertilizer N requirements of wheat in the GM system in the last 6 years. These savings in N fertilizer, together with savings in tillage and herbicide costs for weed control on partial-fallow vs conventional-fallow areas, and higher revenues from the enhanced grain protein, more than offset the added costs for seed and management of the GM crop. Thus, our results imply that, with proper management and given sufficient time, an annual legume GMcereal rotation is a viable option for area producers