152 research outputs found

    A Novel Approach to Visualize and Quantify the Transient Air Infiltration/Exfiltration in Walk-in Coolers

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    Walk-in coolers are room-sized, insulated, and refrigerated compartments for food product storage. Walk-ins have areas equal or below 280 m2 (3,000 ft2), and are classified either as coolers operating above 0 degrees C (32 degrees F) (medium-temperature) to store fresh fruit, vegetables, and dairy products, or freezers that operate below 0 degrees C (32 degrees F) (low-temperature) to meet health and safety standards of frozen food products. Walk-ins are typically found in restaurants as well as small- and medium-to-large grocery stores or supermarkets

    Evaluation of Measurement Performance in Averaging Quantization System with Noise

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    Statistical description of quantization process is common in the theory of quantization. For the case of nonsubtractive dither theoretical analyses of the dithered quantizer have been confronted with experimental results. As a quantization system one-chip microcomputer with the analog-to-digital converter on a chip has been used. Generally valid criteria for dithered system performance have been practically applied for Gaussian dither. Interaction of natural noise present in the signal with an added Gaussian noise of several different disperses and influence of differential nonlinearity of the converter has been observed

    Amtrak Office of Inspector General: Organizational Assessment

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    The Amtrak OIG office engaged the National Academy to conduct an organizational assessment that examines the current operations of the OIG office. The organizational assessment identified core organizational strengths and weaknesses, and recommended specific, prioritized actions to improve OIG processes, policies and management practices that will help the office achieve the goals outlined in its five-year strategic plan.Key FindingsThe observations and recommendations within this report that resulted from key stakeholder interviews, a staff survey and OIG benchmarking research address eight areas of importance to the Amtrak OIG. The report defines the desired future state, summarizes Amtrak OIG's strengths and weaknesses related to the future state, and recommends immediate "quick win" next steps as well as longer-term recommendations. Progress in these areas will significantly contribute to operational improvement. The eight areas address: - Internal Communication- External Communication- Work Planning and Prioritization- Quality and Timely Work Processes- Independence- Policy Management and Updates- Human Capital Management- Performance MeasuresFor each of these eight future states, the Panel identified both "quick win" opportunities as well as longer-term recommendations that the OIG should implement

    Amtrak OIG Organizational Assessment, Phase II: Implementation Roadmap Development

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    In the spring of 2010, the Academy conducted an independent organizational assessment of the Amtrak OIG. The Phase I final report addressed eight critical areas of focus, and for each of the these focus areas, the Academy identified a desired future state, key observations, critical risks, "quick win" opportunities, and long-term recommendations. The Phase I results formed the basis for the Phase II of the organizational assessment.As part of the Phase II study, the Amtrak OIG engaged the Academy to assist the organization in developing Implementation Roadmaps addressing six areas with high levels of urgency. They included: - Internal Communications- Quality and Timely Work Processes- Work Planning and Prioritization- Performance Measures- External Communications- Management and Policy UpdatesThe OIG assembled Working Groups for each of the focus areas, and the Working Groups engaged in 24 thought-provoking discussions facilitated by the Academy's Study Team to develop Implementation Roadmaps. Each Implementation Roadmap consisted of a 12-18 month tactical plan to guide in the accomplishment of the most critical improvements identified in the organizational assessment and provided the information needed for OIG leadership to hold staff accountable for progress on key activites and milestones of the priority issues.In addition to yielding the Implementation Roadmaps, the Working Group sessions had broader impacts on the OIG-wide organization, including building a participative management approach, engaging and empowering staff members, and instituting a sustainable process to improve the organization's operations

    Orbit Determination of LEO Satellites for a Single Pass through a Radar: Comparison of Methods

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    The problem of determining the orbit of a space object from measurements based on one pass through the field of view of a radar is not a new one. Extensive research in this area has been carried out in the USA and Russia since the late 50s when these countries started the development of ballistic missile defense (BMD) and Early Warning systems. In Russia these investigations got additional stimulation in the early 60s after the decision to create a Space Surveillance System, whose primary task would be the maintenance of the satellite catalog. These problems were the focus of research interest until the middle 70s when the appropriate techniques and software were implemented for all radars. Then for more than 20 years no new research papers appeared on this subject. This produced an impression that all the problems of track determination based on one pass had been solved and there was no need for further research. In the late 90s interest in this problem arose again in relation to the following. It was estimated that there would be greater than 100,000 objects with size greater than 1-2 cm and collision of an operational spacecraft with any of these objects could have catastrophic results. Thus, for prevention of hazardous approaches and collisions with valuable spacecraft the existing satellite catalog should be extended by at least an order of magnitude This is a very difficult scientific and engineering task. One of the issues is the development of data fusion procedures and the software capable of maintaining such a huge catalog in near real time. The number of daily processed measurements (of all types, radar and optical) for such a system may constitute millions, thus increasing the number of measurements by at least an order of magnitude. Since we will have ten times more satellites and measurements the computer effort required for the correlation of measurements will be two orders of magnitude greater. This could create significant problems for processing data close to real time even for modern computers. Preliminary "compression" of data for one pass through the field of view of a sensor can significantly reduce the requirements to computers and data communication. This compression will occur when all the single measurements of the sensor are replaced by the orbit determined on their basis. The single measurement here means the radar parameters (range, azimuth, elevation, and in some cases range rate) measured by a single pulse

    Fate of Sessile Droplet Chemical Agents in Environmental Substrates in the Presence of Physiochemical Processes

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    A general-purpose multi-phase and multi-component computer model capable of solving the complex problems encountered in the agent substrate interaction is developed. The model solves the transient and time-accurate mass and momentum governing equations in a three dimensional space. The provisions for considering all the inter-phase activities (solidification, evaporation, condensation, etc.) are included in the model. The chemical reactions among all phases are allowed and the products of the existing chemical reactions in all three phases are possible. The impact of chemical reaction products on the transport properties in porous media such as porosity, capillary pressure, and permeability is considered. Numerous validations for simulants, agents, and pesticides with laboratory and open air data are presented. Results for chemical reactions in the presence of pre-existing water in porous materials such as moisture, or separated agent and water droplets on porous substrates are presented. The model will greatly enhance the capabilities in predicting the level of threat after any chemical such as Toxic Industrial Chemicals (TICs) and Toxic Industrial Materials (TIMs) release on environmental substrates. The model’s generality makes it suitable for both defense and pharmaceutical applications

    Measurement of infiltration rate of warm air into walk-in coolers

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    Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.The tracer gas technique is used to experimentally measure the infiltration of warm air into walk-in coolers during its nominal operating conditions. The tracer gas samples captured before, during, and after the infiltration process are collected through sampling probes inside and outside the cooler. The infiltration rate can be calculated from this data. The transient nature of the infiltration rate that is captured in this approach signifies the shortcoming of the existing methodologies currently practiced in industry. It is found that the infiltration rate is a function of the temperature gradient between the inside and outside air, relative humidity, and the void volume in the cooler. It is also demonstrated that it is possible to derive a closed form equation based on the experimental data that can replace the current equations.dc201

    On the dispersionless Kadomtsev-Petviashvili equation in n+1 dimensions: exact solutions, the Cauchy problem for small initial data and wave breaking

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    We study the (n+1)-dimensional generalization of the dispersionless Kadomtsev-Petviashvili (dKP) equation, a universal equation describing the propagation of weakly nonlinear, quasi one dimensional waves in n+1 dimensions, and arising in several physical contexts, like acoustics, plasma physics and hydrodynamics. For n=2, this equation is integrable, and it has been recently shown to be a prototype model equation in the description of the two dimensional wave breaking of localized initial data. We construct an exact solution of the n+1 dimensional model containing an arbitrary function of one variable, corresponding to its parabolic invariance, describing waves, constant on their paraboloidal wave front, breaking simultaneously in all points of it. Then we use such solution to build a uniform approximation of the solution of the Cauchy problem, for small and localized initial data, showing that such a small and localized initial data evolving according to the (n+1)-dimensional dKP equation break, in the long time regime, if and only if n=1,2,3; i.e., in physical space. Such a wave breaking takes place, generically, in a point of the paraboloidal wave front, and the analytic aspects of it are given explicitly in terms of the small initial data.Comment: 20 pages, 10 figures, few formulas adde

    Predictors, type, and impact of bleeding on the net clinical benefit of long-term ticagrelor in stable patients with prior myocardial infarction

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    BACKGROUND: Ticagrelor reduces ischemic risk but increases bleeding in patients with prior myocardial infarction. Identification of patients at lower bleeding risk is important in selecting patients who are likely to derive more favorable outcomes versus risk from this strategy. METHODS AND RESULTS: PEGASUS-TIMI 54 (Prevention of Cardiovascular Events in Patients With Prior Heart Attack Using Ticagrelor Compared to Placebo on a Background of Aspirin—Thrombolysis in Myocardial Infarction 54) randomized 21 162 patients with prior myocardial infarction in a 1:1:1 fashion to ticagrelor 60 mg or 90 mg twice daily or placebo, with ticagrelor 60 mg approved for long-term use. TIMI major or minor bleeding was the primary end point for this analysis. Causes of bleeding were categorized by site and etiology, and independent predictors were identified. At 3 years, ticagrelor 60 mg increased the rate of TIMI major or minor bleeding by 2.0% versus placebo (1.4% placebo versus 3.4% ticagrelor). The bleeding excess was driven primarily by spontaneous gastrointestinal bleeds. A history of spontaneous bleeding requiring hospitalization and the presence of anemia were independent predictors of bleeding but not of ischemic risk. Patients with at least 1 risk predictor had 3-fold higher rates of bleeding with ticagre-lor 60 mg versus those who had neither (absolute risk increase, 4.4% versus 1.5%; P=0.01). Patients with neither predictor had a more favorable benefit profile with ticagrelor 60 mg versus placebo including lower mortality (hazard ratio, 0.79; 95% CI, 0.65–0.96; P interaction = 0.03). CONCLUSIONS: In patients with prior myocardial infarction, bleeding with ticagrelor 60 mg twice daily is predominantly spontaneous gastrointestinal. A history of spontaneous bleeding requiring hospitalization or the presence of anemia identifies patients at higher risk of bleeding, and the absence of either identifies patients likely to have a more favorable net benefit with ticagrelor

    Синтез и исследование влияния аналога аргинин-вазопрессина (6-9) на поведение крыс различных возрастных групп

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    The article presents the synthesis and results of the study of the effect of chronic neonatal administration by intranasal method of an analogue of the C-terminal fragment of arginine-vasopressin (AVP) - N-Ac-DMet-Pro-Arg-Gly-NH2 on the training and level of depression in white rats of three age groups. It is shown that the most significant effect of the analogue was manifested in the test for the development of conditional reaction of active avoidance. A favorable effect on the degree of depression of animals is also well expressed. According to the data obtained, we conclude that the action of the peptide is manifested only under the influence of a biologically significant stimulus. Разработана методика синтеза аналога С-концевого фрагмента аргинин-вазопрессина (АВП) -N-Ac-DMet-Pro-Arg-Gly-NH2. Изучено влияние хронического неонатального введения N-Ac-DMet-Pro-Arg-Gly-NH2 интраназальным методом на обучение и степень депрессивности белых крыс трех возрастных групп. Показано, что наиболее существенное действие аналога проявилось в тесте на выработку условной реакции активного избегания. Также хорошо выражено благоприятное влияние на степень депрессивности животных. Согласно полученным данным, можно предположить, что действие пептида проявляется только при воздействии биологически значимого стимула
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