Maize-nutrient response information applied across Sub-Saharan Africa

The profit potential for a given investment in fertilizer use can be estimated using representative crop nutrient response functions. Where response data is scarce, determination of representative response functions can be strengthened by using results from homologous crop growing conditions. Maize (Zea mays L.) nutrient response functions were selected from the Optimization of Fertilizer Recommendations in Africa (OFRA) database of 5500 georeferenced response functions determined from field research conducted in Sub-Saharan Africa. Three methods for defining inference domains for selection of response functions were compared. Use of the OFRA Inference Tool (OFRA-IT; http://agronomy.unl.edu/OFRA) resulted in greater specificity of maize N, P, and K response functions with higher R² values indicating superiority compared with using the Harvest Choice Agroecological Zones (HC-AEZ) and the recommendation domains of the Global Yield Gap Atlas project (GYGA-RD). The OFRA-IT queries three soil properties in addition to climate-related properties while the latter two options use climate properties only. The OFRA-IT was generally insensitive to changes in criteria ranges of 20–25% used in queries suggesting value in using wider criteria ranges compared with the default for information scarce crop nutrient response functions.     

QoSPlan: A Measurement Based Quality of Service aware Network Planning Framework

In this article we present QoSPlan—a measurement based framework for preparing information relevant to Quality of Service (QoS)-aware IP network planning, which aims at reducing a core operational expenditure for the network operator. QoSPlan is designed to reduce the cost of deployment and maintenance of network monitoring systems. The process involves analysis of pre-existing accounting data to estimate a network-wide traffic matrix. Part of this estimation process relates to the generalization of QoS-related effective bandwidth coefficients taken from traffic analyzed on the network. We offer recommendations on how to appropriately realize QoSPlan to maximize its accuracy and effectiveness when applied to different network traffic scenarios. This is achieved through a thorough sensitivity analysis of the methods proposed using real traffic scenarios and indicative network topologies. We also provide an economic analysis of the deployment and maintenance costs associated with QoSPlan in comparison to a direct measurement approach, demonstrating cost savings of up to 60 % given different topology sizes.     

An interactive computer-based interface to support the discovery of individuals’ mental representations and preferences in decisions problems: An application to travel behavior

Growing emphasis is currently given in decision modeling on process data to capture behavioral mechanisms that ground decision-making processes. Nevertheless, advanced applications to elicit such data are still lacking. The Causal Network Elicitation Technique interview and card-game, both face-to-face interviews, are examples of a behavioral process method to obtain individuals’ decision-making by eliciting temporary mental representations of particular problems. However, to portray and model these representations into formal modeling approaches, such as Bayesian decision networks, an extensive set of parameters has to be gathered for each individual. Thus, data collection procedures for large sample groups can be costly and time consuming. This paper reports on the methodological conversion and enhancement of the existing elicitation methods into a computer-based interface that allows to not only uncover individuals’ mental representations but also to automate the generation of preference parameter elicitation questions. Results of such studies can be used to understand individuals’ constructs and beliefs with respect to decision alternatives, predict individuals’ decision behavior at a disaggregate level, and to assess behavioral changes due to differences in contexts and constraints.     

Effect of temperature on the water retention properties of two high performance concretes

This contribution aims at (1) determining experimentally the first desorption isotherms of two high performance concretes (based on CEM I and CEM V cements), at three different temperature levels T = 20, 50 and 80 °C, and (2) showing whether these may be simply described by adsorption and capillarity.Results at 20 °C compare well with recently published results; in particular, an important desorption is observed at high RH (≥ 98%). A simple pore network model, based on Kelvin–Laplace's capillary theory, is implemented, and shows the existence of two main de-saturation modes, one at high pore radii (capillary pores), the other for pore radii on the order of a few nanometers (C-S-H porosity), where desorption is shown to occur. A complementary drying mechanism is evidenced at 80 °C, which is attributed to ettringite and/or C-S-H degradation. Finally, proper numerical fitting of all isotherm data is achieved using the well-known three-parameter BSB model.     

Effect of a high calcite filler addition upon microstructural, mechanical, shrinkage and transport properties of a mortar

Sands produced from limestone rock deposits in Algeria contain high proportions of fine 0/100 μm particles (named filler hereafter), which are available in large quantities. This study aims to identify the maximum filler amount which may be added to cementitious materials without performance loss. Performance is quantified here as related to varied properties, either microstructural (density, porosity, pore size distribution, capillary absorption, Klinkenberg effect), mechanical (Young's modulus, compressive and flexural strengths), or indicative of durability (intrinsic gas permeability, drying shrinkage and mass loss). To that purpose, mortars with various amounts of filler, ranging from 15 to 45% sand mass (i.e. 45 to 135% cement mass), have been formulated, tested and compared to a reference mortar. As recommended by J. Baron [J. Baron, Les additions normalisées pour le Béton, Les bétons - Bases et données pour leur formulation, Association technique - industrie des liants hydrauliques (in French), Eyrolles Ed., Paris, 1996, pp. 47-57], substitution to sand is privileged, whereby cement proportion and workability are kept constant while water need varies with increasing filler amount. Preliminary XRD analysis of filler powder shows no other minerals than calcite CaCO₃ and traces of dolomite CaMg(CO₃)₂. Results point out the existence of an optimal performance value and a high effect of filler addition. In particular, for high filler amounts, total porosity increases while bigger pore populations diminish. This is confirmed by SEM examinations of the microstructure as well as by the increase of Klinkenberg coefficient β determined from gas permeability measurements, and by capillary absorption results. Moreover, intrinsic gas permeability, compressive and flexural strengths remain remarkably high whatever the filler proportion. Drying shrinkage and mass loss are not impacted dramatically either.     

CLA-Rich Soy Oil Margarine Production and Characterization

A heterogeneous catalysis method to produce 20 % conjugated linoleic acid (CLA)-rich food-grade soy oil in 2 h without solvents or gases was recently developed. The objective of this study was to produce and characterize CLA-rich soy oil margarine relative to a soy oil control and commercial margarine. CLA-rich soy oil was used to prepare margarine. The samples were characterized for firmness, rheology, thermal behavior, solid fat content (SFC) and microstructure and compared with a soy oil control and commercial margarine. The CLA-rich oil margarine firmness and rheological properties were similar to commercial margarine and provided a better texture relative to the soy oil control margarine. However, SFC, droplet size distribution and melting behavior of CLA-rich oil margarine were similar to control soy oil margarine and dissimilar to the commercial product. This suggests that hardness and rheological properties of margarine are not solely dependent on SFC and melting behavior. Lipid composition, polymorphism and microstructure differences in CLA-rich oil margarine may play an important role on the texture and rheological properties. A 7-g typical serving of the CLA-rich oil margarine will provide 0.6 g CLA. Thus five servings will provide 3.2 g/day of CLA and 185 calories/day, which is well within the maximum recommended 700–980 fat calories/day.     

A Marine Propeller Aerodynamic Test Facility

Abstract:  Conventional propeller test facilities such as tow tanks, cavitation tunnels and the open sea have various limitations such as cost, accessibility, size and accuracy. An aerodynamic marine propeller test facility has been developed at the University of British Columbia to allow for performance evaluations of full-size marine propellers in the highly controlled environment of a wind tunnel. Thorough static and dynamic calibrations of the test rig confirmed that the sensors have a highly linear response with essentially zero crosstalk between the thrust and torque signals. Performance curves acquired from a commercial 24 × 24 propeller show that the repeatability error of the torque and thrust measurements is <1%. The uncertainties of the advance ratio, torque coefficient, thrust coefficient, and efficiency are 0.2%, 0.5%, 0.1%, and 1%, respectively. Performance curves measured over a range of the Reynolds numbers show that Reynolds number independence is achieved for Reynolds numbers above approximately 5 × 10⁵.