250 research outputs found

    THE EFFECT OF PERSONAL AND FARM CHARACTERISTICS UPON GRAIN MARKETING PRACTICES

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    A survey of Kansas, Texas, and Iowa agricultural producers was taken to examine the factors affecting their grain marketing practices. Sales indices models and models of qualitative choice are used to determine whether marketers' choices of cash market, forward contract, or futures and options oriented marketing practices are significantly affected by their personal farm business characteristics. Results indicate that geographic location, farm size, grain enterprise specialization, farming experience, use of grain storage, and use of crop insurance have significant effects upon the respondents' choice of grain marketing practices.agricultural options, cash marketing, futures, grain marketing practices, multinomial logit, Tobit, Marketing,

    Specifying and Synthesizing Energy-Efficient Production System Controllers that Exploit Braking Energy Recuperation

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    Reducing the energy consumption is a major concern in industrial production systems. One approach is recuperating the braking energy of robot axes. Ideally, their acceleration and deceleration phases should be synchronized so that the braking energy of one axis can be reused directly to accelerate another. This requires a detailed alignment of the axes' trajectories, but also a careful design of the overall discrete control. Finding an optimal control strategy manually, however, is difficult, as also many functional and safety requirements must be considered. We therefore propose an automated methodology that consists of three parts: (1) A scenario-based language to flexibly specify the discrete production system behavior, (2) an automated procedure to synthesize optimal control strategies from such specifications, including PLC code generation, and (3) a procedure for the detailed trajectory optimization. We describe the methodology, focusing on parts (1) and (2) in this paper, and present tool support and evaluation results

    Beware of CaBER: filament thinning rheometry doesn't give `the' relaxation time of polymer solutions

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    The viscoelastic relaxation time {\tau} of a polymer solution is often measured using Capillary Breakup Extensional Rheometry (CaBER) where a droplet is placed between two plates which are pulled apart to form a thinning filament. For a slow plate retraction protocol, required to avoid inertio-capillary oscillations for low-viscosity liquids, we show experimentally that the CaBER relaxation time inferred from the exponential thinning regime is in fact an apparent relaxation time that increases significantly when increasing the plate diameter and the droplet volume. Similar results are obtained with a Dripping-onto-Substrate (DoS) method. This dependence on the flow history before the formation of the viscoelastic filament is in contradiction with polymer models such as Oldroyd-B that predict a filament thinning rate 1/3{\tau} which is a material property independent of geometrical factors. We show that this is not due to artefacts such as solvent evaporation or polymer degradation and that it cannot be universally explained by the finite extensibility of polymer chains.Comment: 18 pages, 6 figures, presented at the ICR 2023 in Athen

    Evaporation of water:Evaporation rate and collective effects

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    We study the evaporation rate from single drops as well as collections of drops on a solid substrate, both experimentally and theoretically. For a single isolated drop of water, in general the evaporative flux is limited by diffusion of water through the air, leading to an evaporation rate that is proportional to the linear dimension of the drop. Here, we test the limitations of this scaling law for several small drops and for very large drops. We find that both for simple arrangements of drops, as well as for complex drop size distributions found in sprays, cooperative effects between drops are significant. For large drops, we find that the onset of convection introduces a length scale of approximately 20 mm in radius, below which linear scaling is found. Above this length scale, the evaporation rate is proportional to the surface area

    Drop Formation in Non-Newtonian Fluids

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    International audienceWe study the pinch-off dynamics of droplets of yield stress and shear thinning fluids. To separate the two non-Newtonian effects, we use a yield stress material for which the yield stress can be tuned without changing the shear thinning behavior, and a shear thinning system (without a yield stress) for which the shear thinning can be controlled over a large range, without introducing too much elasticity into the system. We find that the pinch-off remains very similar to that of constant viscosity Newtonian liquids, and consequently thinning in shear flow does not imply a thinning in elongational flow

    Aerodynamic Design of a Reusable Booster Stage Flight Experiment

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    The DLR Project ReFEx is a flight experiment to gain experience for future HTVL reusable rocket stages. The focus of this paper lies on the aerodynamic properties and difficulties during the reentry flight. The stable flight envelope, regions with little and without aerodynamic stability and the analysis of various forms of stable and unstable motion are covered. The test flight is scheduled for 2022

    Genescene: Biomedical Text and Data Mining

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    To access the content of digital texts efficiently, it is necessary to provide more sophisticated access than keyword based searching. GeneScene provides biomedical researchers with research findings and background relations automatically extracted from text and experimental data. These provide a more detailed overview of the information available. The extracted relations were evaluated by qualified researchers and are precise. A qualitative ongoing evaluation of the current online interface indicates that this method to search the literature is more useful and efficient than keyword based searching

    ANGELITO [Material gráfico]

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    ÁLBUM FAMILIAR CASA DE COLÓNCopia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201

    The effects of frequent nocturnal home hemodialysis: the Frequent Hemodialysis Network Nocturnal Trial

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    Prior small studies have shown multiple benefits of frequent nocturnal hemodialysis compared to conventional three times per week treatments. To study this further, we randomized 87 patients to three times per week conventional hemodialysis or to nocturnal hemodialysis six times per week, all with single-use high-flux dialyzers. The 45 patients in the frequent nocturnal arm had a 1.82-fold higher mean weekly stdKt/Vurea, a 1.74-fold higher average number of treatments per week, and a 2.45-fold higher average weekly treatment time than the 42 patients in the conventional arm. We did not find a significant effect of nocturnal hemodialysis for either of the two coprimary outcomes (death or left ventricular mass (measured by MRI) with a hazard ratio of 0.68, or of death or RAND Physical Health Composite with a hazard ratio of 0.91). Possible explanations for the left ventricular mass result include limited sample size and patient characteristics. Secondary outcomes included cognitive performance, self-reported depression, laboratory markers of nutrition, mineral metabolism and anemia, blood pressure and rates of hospitalization, and vascular access interventions. Patients in the nocturnal arm had improved control of hyperphosphatemia and hypertension, but no significant benefit among the other main secondary outcomes. There was a trend for increased vascular access events in the nocturnal arm. Thus, we were unable to demonstrate a definitive benefit of more frequent nocturnal hemodialysis for either coprimary outcome

    Goltsov phenomenon as a natural-technogenic electromagnetic discharge of the lithosphere

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    The article presents data on an unusual natural phenomenon that occurred on November 30, 1984 in the village of Goltsovka, Zmeinogorsky District, Altai Territory. It manifested itself in the passage above the village of a luminous ball, which was accompanied by an impact on the surface of the earth and led to some damage to structures and buildings. A detailed description of this unusual phenomenon in the published scientific literature, as far as we know, is practically absent. The article describes this phenomenon, based on data collected soon after the event, with the addition of upto-date clarifying information. A comparison is made with several known cases of ball lightning and a whirlwind. The conclusion is made about an unusually large energy release in the Goltsovka event
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