488 research outputs found

    Simulation Modeling and Analysis of Coal Shipping Operations

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    Computer simulations are increasingly powerful and realistic models for complex real-world scenarios, and our project applies this technology to model a coal transportation case study. Given a baseline scenario of fourteen carriers transporting coal from three U.S. locations to four international locations, we optimize operations in terms of product flow, time required for shipments, and total operation costs. Implementing the case study\u27s factors into modular code, we introduce several potential changes to current operations and develop specific scenarios. Further, in analyzing these scenarios we test for robustness and sensitivity, by changing values such as demand and bad weather occurrences, and noting how well the model responds. We ultimately gain a better intuition of the factors at play, identify optimizations, and develop a more efficient configuration. Also, we note several areas of potential improvement and suggest several directions for future work. Finally, taking advantage of modern graphical software, we present the optimized scenario in an animated interface, including a 3D view of the model and real-time data charts. While delving into complex data to reach the desired results, our model is accessible to a broad audience and presents an intriguing glimpse into the future of computational modeling

    Automated Network Exploitation Utilizing Bayesian Decision Networks

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    Computer Network Exploitation (CNE) is the process of using tactics and techniques to penetrate computer systems and networks in order to achieve desired effects. It is currently a manual process requiring significant experience and time that are in limited supply. This thesis presents the Automated Network Discovery and Exploitation System (ANDES) which demonstrates that it is feasible to automate the CNE process. The uniqueness of ANDES is the use of Bayesian decision networks to represent the CNE domain and subject matter expert knowledge. ANDES conducts multiple execution cycles, which build upon previous action results. Cycles begin by modeling the current belief state using Bayesian decision networks. ANDES uses these networks to select and execute an expected best action. Observed results are used to update the systems current belief state before the next cycle begins. ANDES was tested in a live-execution event, taking place within a virtual network environment. ANDES successfully performed a series of information gathering and remote exploit actions, across multiple network hosts to gain access to the target

    Autonomous control of underground mining vehicles using reactive navigation

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    Describes how many of the navigation techniques developed by the robotics research community over the last decade may be applied to a class of underground mining vehicles (LHDs and haul trucks). We review the current state-of-the-art in this area and conclude that there are essentially two basic methods of navigation applicable. We describe an implementation of a reactive navigation system on a 30 tonne LHD which has achieved full-speed operation at a production mine

    The effect of beliefs about alcohol’s acute effects on alcohol priming and alcohol-induced impairments of inhibitory control

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    Acute alcohol administration can lead to a loss of control over drinking. Several models argue that this ‘alcohol priming effect’ is mediated by the effect of alcohol on inhibitory control. Alternatively, beliefs about how alcohol affects behavioural regulation may also underlie alcohol priming and alcohol-induced inhibitory impairments. Here two studies examine the extent to which the alcohol priming effect and inhibitory impairments are moderated by beliefs regarding the effects of alcohol on the ability to control behaviour. In study 1, following a priming drink (placebo or .5g/kg of alcohol), participants were provided with bogus feedback regarding their performance on a measure of inhibitory control (stop-signal task; SST) suggesting that they had high or average self-control. However, the bogus feedback manipulation was not successful. In study 2, before a SST, participants were exposed to a neutral or experimental message suggesting acute doses of alcohol reduce the urge to drink and consumed a priming drink and this manipulation was successful. In both studies craving was assessed throughout and a bogus taste test which measured ad libitum drinking was completed. Results suggest no effect of beliefs on craving or ad lib consumption within either study. However, within study 2, participants exposed to the experimental message displayed evidence of alcohol-induced impairments of inhibitory control, while those exposed to the neutral message did not. These findings do not suggest beliefs about the effects of alcohol moderate the alcohol priming effect but do suggest beliefs may, in part, underlie the effect of alcohol on inhibitory control

    Career development among young people in Britain today: Poverty of aspiration or poverty of opportunity

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    This paper compares two explanations of the persistent relationship in the UK between young people's social class backgrounds and their rates of participation in higher education: poverty of aspiration and rational action. It is argued that, rather than widening opportunities, successive reforms in education and training have created a series of blind alleys for the (mostly working class) young people who are not high achievers, and that these experiences are the most likely reason for the subsequent strengthening of the weak relationship that exists at age 11/12 between, on one hand, social class backgrounds, then, on the other, pupils' educational and vocational aims. The paper then proceeds to argue that at age 16 to 18 high achievers from working class homes are likely to face equally attractive opportunities to the kinds of higher education that they might otherwise enter

    Magnetic Monopole Noise

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    Magnetic monopoles are hypothetical elementary particles exhibiting quantized magnetic charge m0=±(h/μ0e)m_0=\pm(h/\mu_0e) and quantized magnetic flux Φ0=±h/e\Phi_0=\pm h/e. A classic proposal for detecting such magnetic charges is to measure the quantized jump in magnetic flux Φ\Phi threading the loop of a superconducting quantum interference device (SQUID) when a monopole passes through it. Naturally, with the theoretical discovery that a plasma of emergent magnetic charges should exist in several lanthanide-pyrochlore magnetic insulators, including Dy2_2Ti2_2O7_7, this SQUID technique was proposed for their direct detection. Experimentally, this has proven extremely challenging because of the high number density, and the generation-recombination (GR) fluctuations, of the monopole plasma. Recently, however, theoretical advances have allowed the spectral density of magnetic-flux noise SΦ(ω,T)S_{\Phi}(\omega,T) due to GR fluctuations of ±m∗\pm m_* magnetic charge pairs to be determined. These theories present a sequence of strikingly clear predictions for the magnetic-flux noise signature of emergent magnetic monopoles. Here we report development of a high-sensitivity, SQUID based flux-noise spectrometer, and consequent measurements of the frequency and temperature dependence of SΦ(ω,T)S_{\Phi}(\omega,T) for Dy2_2Ti2_2O7_7 samples. Virtually all the elements of SΦ(ω,T)S_{\Phi}(\omega,T) predicted for a magnetic monopole plasma, including the existence of intense magnetization noise and its characteristic frequency and temperature dependence, are detected directly. Moreover, comparisons of simulated and measured correlation functions CΦ(t)C_{\Phi}(t) of the magnetic-flux noise Φ(t)\Phi(t) imply that the motion of magnetic charges is strongly correlated because traversal of the same trajectory by two magnetic charges of same sign is forbidden

    Seasonal range fidelity of a megaherbivore in response to environmental change

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    For large herbivores living in highly dynamic environments, maintaining range fidelity has the potential to facilitate the exploitation of predictable resources while minimising energy expenditure. We evaluate this expectation by examining how the seasonal range fidelity of African elephants (Loxodonta africana) in the Kruger National Park, South Africa is affected by spatiotemporal variation in environmental conditions (vegetation quality, temperature, rainfall, and fire). Eight-years of GPS collar data were used to analyse the similarity in seasonal utilisation distributions for thirteen family groups. Elephants exhibited remarkable consistency in their seasonal range fidelity across the study with rainfall emerging as a key driver of space-use. Within years, high range fidelity from summer to autumn and from autumn to winter was driven by increased rainfall and the retention of high-quality vegetation. Across years, sequential autumn seasons demonstrated the lowest levels of range fidelity due to inter-annual variability in the wet to dry season transition, resulting in unpredictable resource availability. Understanding seasonal space use is important for determining the effects of future variability in environmental conditions on elephant populations, particularly when it comes to management interventions. Indeed, over the coming decades climate change is predicted to drive greater variability in rainfall and elevated temperatures in African savanna ecosystems. The impacts of climate change also present particular challenges for elephants living in fragmented or human-transformed habitats where the opportunity for seasonal range shifts are greatly constrained
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