11,822 research outputs found

    Antifragility Analysis and Measurement Framework for Systems of Systems

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    The twenty-first century is defined by the social and technical hazards we face. A hazardous situation is a condition, or event, that threatens the well-being of people, organizations, societies, environments, and property. The most extreme of the hazards are considered X-Events and are an exogenous source of extreme stress to a system. X-Events can also be the unintended outputs of a system with both positive (serendipitous) and negative (catastrophic) consequences. Systems can vary in their ability to withstand these stress events. This ability exists on a continuum of fragility that ranges from fragile (degrading with stress), to robust (unchanged by stress), to antifragile (improving with stress). The state of the art does not include a method for analyzing or measuring fragility. Given that what we measure we will improve, the absence of a measurement approach limits the effectiveness of governance in making our systems less fragile and more robust if not antifragile. The authors present an antifragile system simulation model, and propose a framework for analyzing and measuring antifragility based on system of systems concepts. The framework reduces a multidimensional concept of fragility into a two-dimensional continuous interval scale

    Method and apparatus for sensing the regeneration of a diesel engine particulate trap

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    A diesel engine exhaust system is provided with a particulate trap for collecting the products of incomplete combustion during the engine power cycle. A sensing mechanism including an electrode downstream of the trap and a signal generating circuit provides a positive indication of occurrence of regeneration of the trap. Charged particles generated during regeneration induce a charge of the electrode, that charge activates the signal generating circuit and it, in turn, produces an indication external of the exhaust system that trap regeneration is occurring. That indication can be in the operator’s compartment.https://digitalcommons.mtu.edu/patents/1092/thumbnail.jp

    Synthetic perspective optical flow: Influence on pilot control tasks

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    One approach used to better understand the impact of visual flow on control tasks has been to use synthetic perspective flow patterns. Such patterns are the result of apparent motion across a grid or random dot display. Unfortunately, the optical flow so generated is based on a subset of the flow information that exists in the real world. The danger is that the resulting optical motions may not generate the visual flow patterns useful for actual flight control. Researchers conducted a series of studies directed at understanding the characteristics of synthetic perspective flow that support various pilot tasks. In the first of these, they examined the control of altitude over various perspective grid textures (Johnson et al., 1987). Another set of studies was directed at studying the head tracking of targets moving in a 3-D coordinate system. These studies, parametric in nature, utilized both impoverished and complex virtual worlds represented by simple perspective grids at one extreme, and computer-generated terrain at the other. These studies are part of an applied visual research program directed at understanding the design principles required for the development of instruments displaying spatial orientation information. The experiments also highlight the need for modeling the impact of spatial displays on pilot control tasks

    Putting pharmaceuticals into the wider context of challenges to fish populations in rivers

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    The natural range of fish species in our rivers is related to flow, elevation, temperature, local habitat and connectivity. For over 2000 years, humans have altered to varying degrees the river habitat. In the past 200 years, we added to the environmental disruption by discharging poorly treated sewage, nutrients and industrial waste into our rivers. For many rivers, the low point arrived during the period of 1950s–1970s, when rapid economic development overrode environmental concerns and dissolved oxygen concentrations dropped to zero. In these more enlightened times, gross river pollution is a thing of the past in the Developed World. However, persistent legacy chemical contaminants can be found in fish long after their discharge ceased. Changes in habitat quality and morphology caused and continue to cause the disappearance of fish species. The range of fish stressors has now increased as temperatures rise, and non-native fish introductions bring new diseases. The threat from pharmaceuticals to fish populations remains hypothetical, and no studies have yet linked change in fish populations to exposure

    Economic differences between cumulative and episodic reduction of sediment from cropland

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    This study compares measures for reducing cumulative sediment loads from cropland with measures for reducing sediment loads from extreme storms. The issue is whether the optimal means of controlling cumulative loads are very different from the optimal controls for storm event loads. Differences are described in terms of costs and management practices. The analysis entailed developing a storm-event simulation model analogous to the SEDEC sedimentation economics model. The analogue model was used to identify the respective optimal cropland management strategies for various extreme storm conditions. These strategies were then analyzed using the annual average SEDEC, and the optimal strategies from SEDEC were analyzed for their storm-event properties. The comparisons permit conclusions concerning the relative effectiveness of management strategies for achieving cumulative sediment goals versus storm-event load goals. Data for a 223 study site in the Highland-Silver Lake Watershed in Southwestern Illinois were analyzed using this approach. The study produced four main conclusions. First, control costs for episodic sediment loads were consistently higher than the costs for proportionate reductions in annual average loads. Furthermore, strategies for reducing cumulative loads generally achieve less than proportionate reductions in cumulative loads. Second, the highest control costs were generally for the most extreme storms. Third, contour cultivation is a key element of efficient management strategies for row crops. Finally, where a permanent grass crop is grown adjacent to the stream, there is generally little more to be gained by changing upslope management practices. This suggests that grass strips along streams would greatly reduce the need to modify farming practices elsewhere in order to limit sedimentation.U.S. Department of the InteriorU.S. Geological SurveyOpe

    Winning versus losing during gambling and its neural correlates

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    Humans often make decisions which maximize an internal utility function. For example, humans often maximize their expected reward when gambling and this is considered as a "rational" decision. However, humans tend to change their betting strategies depending on how they "feel". If someone has experienced a losing streak, they may "feel" that they are more likely to win on the next hand even though the odds of the game have not changed. That is, their decisions are driven by their emotional state. In this paper, we investigate how the human brain responds to wins and losses during gambling. Using a combination of local field potential recordings in human subjects performing a financial decision-making task, spectral analyses, and non-parametric cluster statistics, we investigated whether neural responses in different cognitive and limbic brain areas differ between wins and losses after decisions are made. In eleven subjects, the neural activity modulated significantly between win and loss trials in one brain region: the anterior insula (p=0.01p=0.01). In particular, gamma activity (30-70 Hz) increased in the anterior insula when subjects just realized that they won. Modulation of metabolic activity in the anterior insula has been observed previously in functional magnetic resonance imaging studies during decision making and when emotions are elicited. However, our study is able to characterize temporal dynamics of electrical activity in this brain region at the millisecond resolution while decisions are made and after outcomes are revealed

    The New Economics of Livestock Production Management

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    The importance of heterogeneity of animal attributes in livestock production is assessed. Preliminary results indicate that variance and skew measures of attributes may be becoming more important over time.livestock economics, herd management, livestock marketing, Livestock Production/Industries, Marketing,

    Efficient Algorithm for Nonpoint Source Pollution Control Problems

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    A dynamic programming algorithm is proposed for a class of nonpoint source pollution control problems. The inherently combinatorial nature of these problems--stemming from the discrete nature of the decision variables, which are production and conservation practices--gives them a special knapsack structure with multiple right hand sides and additional multiple choice constraints. This paper focuses on the computer implementation of this algorithm and its numerical testing and behavior compared with standard integer programming codes. The results show the robustness and relative efficiency of the approach. Furthermore, this paper demonstrates that dynamic programming can be used to generate sensitivity analysis information for multiple choice knapsack problems
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