Stability of a premixed flame in stagnation-point flow against general disturbances

Previously, the stability of a premixed flame in a stagnation flow was discussed for a restricted class of disturbances that are self-similar to the basic undisturbed flow; thus, flame fronts with corrugations only in the cross stream direction were considered. Here, we consider a more general class of three-dimensional flame front perturbations which also permits corrugations in the streamwise direction. It is shown that, because of the stretch experienced by the flame, the hydrodynamic instability is limited only to disturbances of short wavelength. If in addition diffusion effects have a stabilizing influence, as would be the case of mixtures with Lewis number greater than one, a stretched flame could be absolutely stable. Instabilities occur when the Lewis number is below some critical value less than one. Neutral stability boundaries are presented in terms of the Lewis number, the strain rate, and the appropriate wavenumbers. Beyond the stability threshold, the two-dimensional self-similar modes always grow first. However, if disturbances of long wavelength are excluded, it is possible for the three-dimensional modes to be the least stable one. Accordingly, the pattern that will be observed on the flame front, at the onset of instability, will consist of either ridges in the direction of stretch or the more common three-dimensional cellular structure

The total nucleon-nucleon cross section at large N_c

It is shown that at sufficiently large $N_c$ for incident momenta which are much larger than the QCD, the total nucleon-nucleon cross section is independent of incident momentum and given by $\sigma^{\rm total}=2 \pi \log^2(N_c) / (m^2_{\pi})$. This result is valid in the extreme large $N_c$ regime of $\log(N_c) \gg 1$ and has corrections of relative order $\log (\log(N_c))/\log(N_c)$. A possible connection of this result to the Froissart-Martin bound is discussed.Comment: 4 page

Transitioning from Transaction-Based Markets to Alliance-Based Supply Chains: Implications for Firms

Industrial Organization,

1997 PRICING PERFORMANCE OF MARKET ADVISORY SERVICES FOR CORN AND SOYBEANS

The purpose of this research report is to present an evaluation of advisory service pricing performance in 1997 for corn and soybeans. Specifically, the average price received by a subscriber to an advisory service is calculated for corn and soybean crops harvested in 1997. The average net advisory price across all 23 corn programs is $2.32 per bushel. The net advisory prices for corn range from a minimum of$2.00 per bushel to a maximum of $2.74 per bushel. The average net advisory price across all 21 soybean programs is$6.40 per bushel. The net advisory prices for soybeans range from a minimum of $6.08 per bushel to a maximum of$6.99 per bushel.evaluation of advisory services, pricing performance, soybeans, C8, D4, D8, L1, M3, Q0, Z0, Marketing,

1995 PRICING PERFORMANCE OF MARKET ADVISORY SERVICES FOR CORN AND SOYBEANS

The purpose of this research report is to present an evaluation of advisory service pricing performance in 1995 for corn and soybeans. Specifically, the average price received by a subscriber to an advisory service is calculated for corn and soybean crops harvested in 1995. The average net advisory price across all 25 corn programs is $3.04 per bushel. The range of net advisory prices for corn is quite large, with a minimum of$2.34 per bushel and a maximum of $3.81 per bushel. The average net advisory price across all 25 soybean programs is$6.61 per bushel. As with corn, the range of net advisory prices for soybeans is substantial, with a minimum of $5.75 per bushel and a maximum of$7.92 per bushel.Agricultural Market Advisory Service (AgMAS) Project, D4, D7, D8, G1, G2, H4, H8, Q1, Z1, Marketing,

DEVELOPMENT OF A MARKET BENCHMARK PRICE FOR AGMAS PERFORMANCE EVALUATIONS

The purpose of this research report is to identify the appropriate market benchmark price to use to evaluate the pricing performance of market advisory services that are included in the annual AgMAS pricing performance evaluations. Five desirable properties of market benchmark prices are identified. Three potential specifications of the market benchmark price are considered: the average price received by Illinois farmers, the harvest cash price, and the average cash price over a two-year crop marketing window. The average cash price meets all of the desired properties, except that it would not be easily implementable by producers. It can be shown, though, that the price realized via a more manageable strategy of "spreading" sales during the marketing window very closely approximates the average cash price. Therefore, it is determined that the average cash price meets all five selection criteria, and is the most appropriate market benchmark to be used in evaluating the pricing performance of market advisory services.advisory services, evaluating the pricing performance, market benchmark price, C8, C0, D4, D8, L1, M3, Q0, Z0, Marketing,

1996 PRICING PERFORMANCE OF MARKET ADVISORY SERVICES FOR CORN AND SOYBEANS

The purpose of this research report is to present an evaluation of advisory service pricing performance in 1996 for corn and soybeans. Specifically, the average price received by a subscriber to an advisory service is calculated for corn and soybean crops harvested in 1996. The average net advisory price across all 26 corn programs is $2.63 per bushel. The range of net advisory prices for corn is quite large, with a minimum of$2.08 per bushel and a maximum of $3.12 per bushel. The average net advisory price across all 24 soybean programs is$7.27 per bushel. As with corn, the range of net advisory prices for soybeans is substantial, with a minimum of $6.80 per bushel and a maximum of$7.80 per bushel.Agricultural Market Advisory Services, G1, D8, D7, D4, G2, H4, H8, Q1, Z1, Marketing,

DO AGRICULTURAL MARKET ADVISORY SERVICES BEAT THE MARKET? EVIDENCE FROM THE CORN AND SOYBEAN MARKETS OVER 1995-1997

The purpose of this paper is to address two basic performance questions for market advisory services: 1) Do market advisory services, on average, outperform an appropriate market benchmark? and 2) Do market advisory services exhibit persistence in their performance from year-to-year? Data on corn and soybean net price received for advisory services, as reported by the AgMAS Project, are available for the 1995, 1996 and 1997 marketing years. Performance test results suggest that, on average, market advisory services exhibit a small ability to "beat the market" for the 1995 through 1997 corn and soybean crops. This conclusion is somewhat sensitive to the type of performance test and market benchmark considered. The predictability results provide little evidence that future advisory service pricing performance can be predicted from past performance. When services are grouped by performance quantile, some evidence of predictability is found for the poorest performing services, but not for top performing services.Marketing,

THE PRIVATE SECTOR APPROACH TO GRAIN MARKETING: THE CASE OF AGRICULTURAL MARKET ADVISORY SERVICES

The purpose of this paper is to investigate the pricing performance and behavior of market advisory services in corn and soybeans. Data on corn and soybean net price received for advisory services, as reported by the AgMAS Project, are available for the 1995, 1996 and 1997 marketing years. Performance test results suggest that, on average, market advisory services exhibit a small ability to "beat the market". This conclusion is somewhat sensitive to the type of performance test and market benchmark considered. The predictability results provide little evidence that future advisory service pricing performance can be predicted from past performance. Marketing profiles identify three marketing "styles": i) "scale-up" sales, ii) selective hedging and iii) "speculative" hedging. Advisory services tend to follow the same approach across crop years.Agribusiness,