3,034 research outputs found

    Thoughts of You

    Get PDF

    Control Force Compensation in Ground-Based Flight Simulators

    Get PDF
    This paper presents the results of a study that investigated if controller force compensations accounting for the inertial force and moment due to the aircraft motion during flight have a significant effect on pilot control behavior and performance. Seven rotorcraft pilots performed a side-step and precision hovering task in light turbulence in the Vertical Motion Simulator. The effects of force compensation were examined for two different simulated rotorcraft: linear and UH-60 dynamics with two different force gradient of the lateral stick control. Four motion configurations were used: large motion, hexapod motion, fixed-base motion, and fixed-base motion with compensation. Control-input variables and task performance such as the time to translate to the designated hover position, station-keeping position errors, and handling qualities ratings were used as measures. Control force compensation enabled pilot control behavior and performance more similar to that under high- or medium-fidelity motion to some extent only. Control force compensation did not improve overall task performance considering both rotorcraft models at the same time. The control force compensation had effects on the linear model with lighter force gradient, but only a minimal effect on pilots? control behavior and task performance for the UH-60 model, which had a higher force gradient. This suggests that the control force compensation has limited benefits for controllers that have higher stiffness

    Circular 64

    Get PDF
    Treatment of Alaska-produced food products by ionizing radiation may benefit the seafood and agricultural industries and the Alaskan consumer. A feasibility study to evaluate the potential social and economic benefits and risks as well as the costs of using the process in Alaska on Alaskan products is being coordinated by the Institute of Northern Engineering. A research and development project to determine effects on the quality o f Alaskan products could be the next phase in the introduction o f a new food-preservation technique to Alaska

    On the Substitution of Identicals in Counterfactual Reasoning

    Get PDF
    It is widely held that counterfactuals, unlike attitude ascriptions, preserve the referential transparency of their constituents, i.e., that counterfactuals validate the substitution of identicals when their constituents do. The only putative counterexamples in the literature come from counterpossibles, i.e., counterfactuals with impossible antecedents. Advocates of counterpossibilism, i.e., the view that counterpossibles are not all vacuous, argue that counterpossibles can generate referential opacity. But in order to explain why most substitution inferences into counterfactuals seem valid, counterpossibilists also often maintain that counterfactuals with possible antecedents are transparency‐preserving. I argue that if counterpossibles can generate opacity, then so can ordinary counterfactuals with possible antecedents. Utilizing an analogy between counterfactuals and attitude ascriptions, I provide a counterpossibilist‐friendly explanation for the apparent validity of substitution inferences into counterfactuals. I conclude by suggesting that the debate over counterpossibles is closely tied to questions concerning the extent to which counterfactuals are more like attitude ascriptions and epistemic operators than previously recognized

    Numerical investigations of seasonal and interannual variability of North Pacific Subtropical Mode Water and its implications for Pacific climate variability

    Get PDF
    Author Posting. © American Meteorological Society, 2011. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 24 (2011): 2648–2665, doi:10.1175/2010JCLI3435.1.North Pacific Subtropical Mode Water (NPSTMW) is an essential feature of the North Pacific subtropical gyre imparting significant influence on regional SST evolution on seasonal and longer time scales and, as such, is an important component of basin-scale North Pacific climate variability. This study examines the seasonal-to-interannual variability of NPSTMW, the physical processes responsible for this variability, and the connections between NPSTMW and basin-scale climate signals using an eddy-permitting 1979–2006 ocean simulation made available by the Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2). The monthly mean seasonal cycle of NPSTMW in the simulation exhibits three distinct phases: (i) formation during November–March, (ii) isolation during March–June, and (iii) dissipation during June–November—each corresponding to significant changes in upper-ocean structure. An interannual signal is also evident in NPSTMW volume and other characteristic properties with volume minima occurring in 1979, 1988, and 1999. This volume variability is correlated with the Pacific decadal oscillation (PDO) with zero time lag. Further analyses demonstrate the connection of NPSTMW to the basin-scale ocean circulation. With this, modulations of upper-ocean structure driven by the varying strength and position of the westerlies as well as the regional air–sea heat flux pattern are seen to contribute to the variability of NPSTMW volume on interannual time scales.Support for this research was provided by the Partnership for Advancing Interdisciplinary Modeling (PARADIGM), a National Ocean Partnership Program and by a NASA Modeling, Analysis, and the Prediction (MAP) project called Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2)

    UC-30 Malware Analysis Using Reverse Engineering

    Get PDF
    Cybercrimes are a billion-dollar industry that is rapidly growing by the day. One of the biggest threats faced by companies is the infection of malware. New forms of malware are created daily and ever evolving to evade detection methods. Understanding how malware infects your system and how it eludes detection is crucial to keeping a company\u27s network and devices safe. During this project we will be using reverse engineering methods to better understand the functionality of malware, as well as how it eludes detection. We will be using IDAPro and WiDbg to perform the reverse engineering. Using this knowledge, we will create a set of security standards to help companies to protect themselves from these infections. We will also create a document on how to secure a virtual machine for malware analysis. This will help future students who also are interested in analyzing malware themselves. Our preliminary results include understanding some of the most used forms of malware evasion techniques. These techniques include stalling delays, which is when a piece of malware remains idle to defeat time-based antivirus scans. Another technique is action required delays, which is when a piece of malware will only execute once an action or group of actions are performed this will trigger the malware to execute. Another way that malware is able to evade detection is fragmentation. In this technique the malware will split into multiple different fragments, which alone do not raise flags as suspicious, then rejoin and execute.Advisors(s): Dr. Hossain ShahriarTopic(s): SecurityIT 498

    Granulocitna rezerva u kronignom eksperimentalnom otrovanju benzenom u štakora

    Get PDF
    The normal two-fold increase in granulocytes in the peripheral circulation induced by corticosteroids was almost abolished in chronic benzene poisoning in rats.Normalno očekivani dvostruki porast granulocita u perifernoj cirkulaciji nakon primjene kortikosteroida izostao je u štakora kronično otrovanih benzenom

    Do Vertebral Chemical Signatures Distinguish Juvenile Blacktip Shark (Carcharhinus limbatus) Nursery Regions in the Northern Gulf of Mexico?

    Get PDF
    Identifying and protecting shark nurseries is a common management strategy used to help rebuild overfished stocks, yet we know little about connectivity between juvenile and adult populations. By analysing trace metals incorporated into vertebral cartilage, it may be possible to infer natal origin based on nursery-specific chemical signatures. To assess the efficacy of this approach, we collected juvenile blacktip sharks (Carcharhinus limbatus; n = 93) from four regions in the Gulf of Mexico in 2012 and 2013 and analysed their vertebral centra with laser ablation-inductively coupled plasma-mass spectrometry. We observed significant regional differences in six element : Ca ratios in both 2012 and 2013. Multi-element chemical signatures were significantly different among regions and between year-classes. Year-class-specific linear discriminant function analysis yielded regional classification accuracies of 81% for 2012 and 85% for 2013, although samples were not obtained from all four regions in 2012. Combining year-classes resulted in an overall classification accuracy of 84%, thus demonstrating the usefulness of this approach. These results are encouraging yet highlight a need for more research to better evaluate the efficacy of vertebral chemistry to study elasmobranch population connectivity
    corecore