Manually testing aircraft functions during factory assembly has been a costly and time-consuming task. In addition, this problem has been compounded by the fact that deliverable cockpit avionics are required during testing and are therefore exposed to the damaging production environment longer. The C-17 aircraft currently requires 48 on-aircraft test procedures (OATP) to verify system operations and airworthiness prior to customer delivery. As a result, the current manual test method equates to over 15,000 test hours per aircraft. This paper discusses the implementation of the Production Automated Verification Equipment (PAVE). PAVE is an automated aircraft test system which, by emulating various cockpit LRUs and test procedures, automates the current manually intensive OATP testing.
Extracorporeal membrane oxygenation (ECMO) is indicated when conventional measures fail to support a patient during cardiac or respiratory failure. Due to the complicated nature of ECMO, patients often require transport to a tertiary care center. This study retrospectively compared the performance of the Cardiohelp™ (Maquet) life support system with a previously used ECMO circuit when transporting adult patients on venoarterial ECMO between facilities. Two ECMO circuits were compared for performance: 1) the Cardiohelp™ (Maquet) life support system and 2) the “standard” circuit consisting of a Thoratec CentriMag centrifugal pump, Maquet Quadrox-D oxygenator, and a Terumo CDI-500 in-line blood gas analyzer. After analyzing data from 16 patients (eight patients supported with each ECMO system), no differences in patient demographics, percentage of patients successfully weaned from ECMO, percentage of patients surviving to discharge, duration supported on the initial ECMO system, or total duration of ECMO were noted. No patient deaths were related to circuit failure or circuit disruptions in either group. Analysis of the performance of the ECMO circuits and the resulting patient status showed few significant differences between ECMO groups (Cardiohelp™ vs. standard circuit) and time points (the first 8 hours vs. a 24-hour time point). The statistically significant differences were not concerning in terms of appropriate medical support or patient safety. Of interest, the transmembrane pressure was significantly lower for the Cardiohelp™ module vs. the standard oxygenator during the first 8 hours (20.1 [5.3] vs. 37.1 [7.1] mmHg; p < .001) and at 24 hours (21.3 [3.8] vs. 34.8 [7.9] mmHg; p = .001). The Cardiohelp™ portable life support system provides safe and reliable support for adult patients on ECMO during interhospital patient transport as compared to the standard circuit.
Application and installation of high-power AFD's (Adjustable Frequency Drives) in the oil and gas industry requires a significant allocation of resources and a large "tool box" in the evaluation and deployment of tailing pumps as capital equipment. This paper was authored to describe a single successful installation of a 16,500 HP medium voltage AFD replacing an existing tailing pump AFD in an effort to increase process availability. This case study was written in a manner to provide a roadmap of key performance indicators, AFD design characteristics, life-cycle phases, and target measures used to support the goals and objectives of efforts in engineering, operations, and maintenance planning. This paper includes an explanation of major life-cycle stages of the project such as: initial planning; design for the purpose of modernization; business case development for funding approval; project execution through detailed engineering; manufacturing and functional testing; project execution; installation; commissioning; trial runs; factory acceptance testing; development of a maintenance strategy and planning for future replacement. The paper also addresses engineering of major AFD elements (power conversion, cooling system, control system and accessories).
Decision analysis and risk analysis techniques are used to analyze and evaluate a wide variety of problems. Recently, the electric utility industry has used these techniques for health, environmental, and economic risks associated with current and past operations. In some instances, the true health and environmental hazards posed by certain chemicals (for example, PCBs and dioxin) may be controversial and widely debated by the scientific and regulatory community. Regardless of the outcomes of such debates, the continued use or presence of these chemicals may pose a very real economic risk to the utility in the form of cleanup costs, fines, liabilities, public relations, or other direct or indirect costs. Decision analysis and risk analysis techniques are used to manage these economic risks. In other contexts, the utility may need an accurate quantitative assessment of health and environmental risks and an evaluation of alternative mitigation strategies. Some of the same techniques are applied to the environmental risk analysis problem.
Earlier, we reported that in-vitro incubation of blood for ten minutes with the perfluorocarbon (PFC) emulsion Fluosol increased leukocyte activation as determined by adhesion to nylon fiber. In this study, we examined if in-vivo treatment with these PFC emulsions affected the expression of the leukocyte adhesion protein CD11b (primarily found on PMNs) and the generation of leukocyte-derived reactive oxygen species (ROS, oxygen free radicals). Rats were anesthetized and catheterized. Three groups were studied: 1) a phosphate buffered saline (PBS) control group (n=6), 2) a group treated with Fluosol emulsion (1.08g PFC/kg, n=6) and 3) a group treated with perflubron emulsion (1.08g PFC/kg, n=6). Blood samples were taken before and 10, 20, 40 and 60 minutes after treatment for hematology and analysis of PMN CD11b expression and ROS production using flow cytometry. We found that Fluosol caused significant increases in both neutrophil surface expression of CD11b and ROS generation (p<0.05, ANOVA). In the Fluosol group, the peak responses in PMN CD11b expression and ROS production were observed ten minutes after treatment. In contrast, treatment with perflubron emulsion did not cause a significant increase in CD11b expression nor an increase in ROS production at any time after treatment. These findings suggest that Fluosol causes a transient PMN activation in-vivo. The activation of circulating PMNs, in-vivo, is sufficient to significantly enhance oxygen derived free radical production. The lack of a PMN response to perflubron emulsion in-vivo suggests that this agent is not likely to induce a leukocyte-mediated inflammatory response.
The feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery currently being developed for long-term space missions are assessed. The study was performed for a 50-kWe Reference Stirling Space Power Converter (RSSPC) which currently uses hydrostatic gas bearings to support the reciprocating displacer and power piston assemblies. Active magnetic bearings of the attractive electromagnetic type are feasible for the RSSPC power piston. Magnetic support of the displacer assembly would require unacceptable changes to the design of the current RSSPC. However, magnetic suspension of both displacer and power piston is feasible for a relative-displacer version of the RSSPC. Magnetic suspension of the RSSPC power piston can potentially increase overall efficiency by 0.5 to 1 percent (0.1 to 0.3 efficiency points). Magnetic bearings will also overcome several operational concerns associated with hydrostatic gas bearing systems. These advantages, however, are accompanied by a 5 percent increase in specific mass of the RSSPC.
Confusion often exists on setting vibrational amplitude limits for rotating machinery. Present day monitoring instrumentation often includes shaft-displacement-type sensors. Specifications for acceptable amplitude limits for vibration are more commonly available for bearing cap or housing vibration and do not reflect levels for shaft amplitudes. An approach is proposed to compute acceptable amplitude levels due to rotating unbalance to protect the rotating components. The approach may be extended to nonsynchronous motions of the rotating shaft.
