130 research outputs found
Watermelon configurations with wall interaction: exact and asymptotic results
We perform an exact and asymptotic analysis of the model of vicious
walkers interacting with a wall via contact potentials, a model introduced by
Brak, Essam and Owczarek. More specifically, we study the partition function of
watermelon configurations which start on the wall, but may end at arbitrary
height, and their mean number of contacts with the wall. We improve and extend
the earlier (partially non-rigorous) results by Brak, Essam and Owczarek,
providing new exact results, and more precise and more general asymptotic
results, in particular full asymptotic expansions for the partition function
and the mean number of contacts. Furthermore, we relate this circle of problems
to earlier results in the combinatorial and statistical literature.Comment: AmS-TeX, 41 page
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Analysis of the distribution of the number of bidders in construction contract auctions
The number of bidders, N, involved in a construction procurement auction is known to have an important effect on the value of the lowest bid and the mark-up applied by bidders. In practice, for example, it is important for a bidder to have a good estimate of N when bidding for a current contract. One approach, instigated by Friedman in 1956, is to make such an estimate by statistical analysis and modelling. Since then, however, finding a suitable model for N has been an enduring problem for researchers and, despite intensive research activity in the subsequent 30 years, little progress has been made, due principally to the absence of new ideas and perspectives. The debate is resumed by checking old assumptions, providing new evidence relating to concomitant variables and proposing a new model. In doing this and in order to ensure universality, a novel approach is developed and tested by using a unique set of 12 construction tender databases from four continents. This shows the new model provides a significant advancement on previous versions. Several new research questions are also posed and other approaches identified for future study
Interpretation of porosity and LWD resistivity from the Nankai accretionary wedge in light of clay physicochemical properties: Evidence for erosion and local overpressuring
International audienceIn this study, we used porosity to assess the compaction state of the Nankai accretionary wedge sediments and any implications for stress and pore pressure. However, hydrous minerals affect porosity measurements, and accounting for them is essential toward defining the interstitial porosity truly representative of the compaction state. The water content of sediments was measured in core samples and estimated from logging data using a resistivity model for shale. We used the cation exchange capacity to correct the porosity data for the amount of water bound to clay minerals and to correct the porosity estimates for the surface conductivity of hydrous minerals. The results indicate that several apparent porosity anomalies are significantly reduced by this correction, implying that they are in part artifacts from hydrous minerals. The correction also improves the fit of porosity estimated from logging-while-drilling (LWD) resistivity data to porosity measured on cores. Low overall porosities at the toe of the accretionary wedge and in the splay fault area are best explained by erosion, and we estimated the quantity of sediments eroded within the splay fault area by comparing porosity-effective stress relationships of the sediments to a reference curve. Additionally, a comparison of LWD data with core data (resistivity and P wave velocity) obtained at Site C0001 landward of the mega-splay fault area, suggested a contribution from the fracture porosity to in situ properties on the formation
Subword complexes, cluster complexes, and generalized multi-associahedra
In this paper, we use subword complexes to provide a uniform approach to
finite type cluster complexes and multi-associahedra. We introduce, for any
finite Coxeter group and any nonnegative integer k, a spherical subword complex
called multi-cluster complex. For k=1, we show that this subword complex is
isomorphic to the cluster complex of the given type. We show that multi-cluster
complexes of types A and B coincide with known simplicial complexes, namely
with the simplicial complexes of multi-triangulations and centrally symmetric
multi-triangulations respectively. Furthermore, we show that the multi-cluster
complex is universal in the sense that every spherical subword complex can be
realized as a link of a face of the multi-cluster complex.Comment: 26 pages, 3 Tables, 2 Figures; final versio
Numerical modeling of the Sakuma Dam reservoir sedimentation
YesThe present study attempts to predict the reservoir sedimentation in 32 km region of the Tenryu River between the Hiraoka and Sakuma Dams in Japan. For numerical simulations of the reservoir sedimentation, the one-dimensional model of the Hydrologic Engineering Centre-River Analysis System (HEC-RAS) is used together with the inclusion of channel geometry, bed gradation curve, Exner-5 bed sorting mechanisms, fall velocity of the particle, and flow and sediment boundary conditions pertaining to modeling region. The modeling region of the Tenryu River is divided into 48 river stations with 47 reaches in the numerical simulations. The numerical model is calibrated using the available data for 48 years from 1957 to 2004. The formulae of sediment transport function, Manning’s roughness coefficient, computational increment and fall velocity have been identified for getting the best estimation of the Sakuma Dam reservoir sedimentation. Combination of obtained sensitive parameters and erodible limits of 2 m gave the best comparison with the measured bed profile. The computed results follow the trend of measured data with a small underestimation. Although Manning’s roughness coefficient has an effect on the sedimentation, no direct relation is found between the Manning’s roughness coefficient and reservoir sedimentation. It is found that the temperature of water has no effect on the reservoir sedimentation
A.I.D. Food Policy Programming: Lessons Learned -- An Assessment of the "Consumption Effects of Agricultural Policies" Project, 1977-1988
Excerpts from the Executive Summary: This report assesses lessons learned from A.I.D. work in food policy under the Consumption Effects of Agricultural Policies (CEAP) project a systems perspective the between 1977-1988. Food policy integrates in relationships between macroeconomic and agricultural sector policies and micro level behavior at the household or firm level, including resultant changes in food consumption patterns, and nutritional effects. The CEAP project has been A.I.D.'s only major effort to address the issue of how improving nutrition and food consumption can be made an integral part of all other A.I.D. activities in nutrition the economic development process. All other A.I.D. activities in nutrition are direct interventions (for example, supplementary feeding programs and vitamin A distribution). The CEAP project pioneered policy-oriented intervention as a part of A.I.D. nutrition strategy. The CEAP project was oriented toward better understanding the interrelationships and effects of agricultural development and food subsidy policies on the food consumption and nutritional status of different socioeconomic groups. The effects of policy decisions on the food consumption patterns of the poor were emphasized. In addition to producing needed knowledge for researchers and policymakers, the project aimed at providing specific technical assistance to A.I.D. missions and host governments, and sponsoring training activities associated with food policy analysis and design. The CEAP project was directed by the A.I.D. Office of Nutrition (A.I.D./S&T/N) and managed by the Nutrition Economics Group (NEG) within the Office of International Cooperation and Development (OICD) of the U.S. Department of Agriculture (USDA). In this assessment, lessons are identified in five general areas: (1) the seventeen CEAP project studies; (2) the design of research and studies; (3) technical assistance; (4) training activities; (5) project administration and management. The lessons are detailed in the text. The report ends with recommendations for future A.I.D. work related to emerging food policy priorities
Somewhere in France
(Published By Maurice Richmond Music Co., Inc.
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