2,252 research outputs found

    Prediction of leaf wetness duration using a fuzzy logic system

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    Models have been developed to estimate leaf wetness duration (LWD) using measured or estimated weather data on the basis of approaches such as energy balance equations, neural networks, and classification and regression trees (CART). Models that embody physical principles ensure spatial portability but usually require accurate and extensive input data to estimate LWD accurately. Empirical models may be more tolerant to errors of input data and require more limited weather inputs, but they rarely possess wide portability because they do not incorporate physical principles. In this study, a hybrid model was developed to incorporate both energy balance principles and empirical approaches by using fuzzy logic. The results suggested that a LWD model based on a fuzzy logic system offers advantages in comparison to the previous models since the model possessed wider portability than strictly empirical models. Empirical methodologies included in the model algorithm allowed a relatively small number of input variables and tolerated imprecise weather data input. The fuzzy LWD model also possessed adaptability to specific circumstances using a correction factor, which can be determined through a simple training process. For example, when LWD was predicted with site-specific weather forecasts in which substantial systematic errors are contained, the fuzzy LWD model was able to forecast LWD accurately using a correction factor. The correction factor also expanded spatial portability of the fuzzy LWD model to environments in which climate conditions differed considerably, e.g., from temperate to tropical zones. The fuzzy LWD model, therefore, deserves further attention as a substitute for current physical and empirical LWD models

    How to read spore forecasting maps

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    In the coming season, forecasting or modeling of rust spore movement has been proposed to provide producers with a tool for rust management. There is a possibility of spore maps being used to guide our scouts if the model is implemented. This article addresses two related aspects: (1) how soybean rust spreads from southern overwintering regions to northern soybean production regions; (2) how to read spore forecasting maps that will be posted on the Web to help us scout soybean rust during the coming growing season

    High-Throughput Screening of Acyl-CoA Thioesterase I Mutants Using a Fluid Array Platform

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    Screening target microorganisms from a mutated recombinant library plays a crucial role in advancing synthetic biology and metabolic engineering. However, conventional screening tools have several limitations regarding throughput, cost, and labor. Here, we used the fluid array platform to conduct high-throughput screening (HTS) that identified Escherichia coli ???TesA thioesterase mutants producing elevated yields of free fatty acids (FFAs) from a large (106) mutant library. A growth-based screening method using a TetA-RFP fusion sensing mechanism and a reporter-based screening method using high-level FFA producing mutants were employed to identify these mutants via HTS. The platform was able to cover >95% of the mutation library, and it screened target cells from many arrays of the fluid array platform so that a post-analysis could be conducted by gas chromatography. The ???TesA mutation of each isolated mutant showing improved FFA production in E. coli was characterized, and its enhanced FFA production capability was confirmed

    Extracting Concrete Thermal Characteristics from Temperature Time History of RC Column Exposed to Standard Fire

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    A numerical method to identify thermal conductivity from time history of one-dimensional temperature variations in thermal unsteady-state is proposed. The numerical method considers the change of specific heat and thermal conductivity with respect to temperature. Fire test of reinforced concrete (RC) columns was conducted using a standard fire to obtain time history of temperature variations in the column section. A thermal equilibrium model in unsteady-state condition was developed. The thermal conductivity of concrete was then determined by optimizing the numerical solution of the model to meet the observed time history of temperature variations. The determined thermal conductivity with respect to temperature was then verified against standard thermal conductivity measurements of concrete bricks. It is concluded that the proposed method can be used to conservatively estimate thermal conductivity of concrete for design purpose. Finally, the thermal radiation properties of concrete for the RC column were estimated from the thermal equilibrium at the surface of the column. The radiant heat transfer ratio of concrete representing absorptivity to emissivity ratio of concrete during fire was evaluated and is suggested as a concrete criterion that can be used in fire safety assessment
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