80 research outputs found
Assessment of Failure Frequencies of Pipelines in Natech Events Triggered by Earthquakes
During a seismic event, underground pipelines can undergo to significant damages with severe implications in terms of life safety and economic impact. This type of scenarios falls under the definition of Natech. In recent years, quantitative risk analysis became a pivotal tool to assess and manage Natech risk. Among the tools required to perform the quantitative assessment of Natech risk, vulnerability models are required to characterize equipment damages from natural events. This contribution is focused on the review of the pipeline vulnerability models available for the case of earthquakes. Two main categories of models have been identified in the literature. A first category proposes the repair rate as performance indicator for the damage of pipeline due to seismic load, and gives as output the number of required repairs per unit length. A second category proposes fragility curves associated with risk states depending on the mechanism of ground failure. In the framework of Natech risk assessment, the latter have the important advantage of having clearly and unambiguously defined the risk status (and thus the extent of the release) with which they are associated. A subset of vulnerability models deemed more appropriate to be applied in the framework of Natech risk assessment is then identified. Their application to the assessment of the expected frequencies of release events due to pipeline damage is provided, enabling their comparison and the discussion of the relative strengths and weaknesses
Reduced-order particle-in-cell simulations of a high-power magnetically shielded Hall thruster
High-power magnetically shielded Hall thrusters have emerged in recent years to meet the needs of the next-generation on-orbit servicing and exploration missions. Even though a few such thrusters are currently undergoing their late-stage development and qualification campaigns, many unanswered questions yet exist concerning the behavior and evolution of the plasma in these large-size thrusters that feature an unconventional magnetic field topology. Noting the complex, multi-dimensional nature of plasma processes in Hall thrusters, high-fidelity particle-in-cell (PIC) simulations are optimal tools to study the intricate plasma behavior. Nonetheless, the significant computational cost of traditional multi-dimensional PIC schemes renders simulating the high-power thrusters without any physics-altering speed-up factors unfeasible. The novel reduced-order “quasi-2D” PIC scheme enables a significant reduction in the computational cost requirement of the PIC simulations. Thus, in this article, we demonstrate the applicability of the reduced-order PIC for a cost-efficient, self-consistent study of the physics in high-power Hall thrusters by performing simulations of a 20 kW-class magnetically shielded Hall thruster along the axial-azimuthal and radial-azimuthal coordinates. The axial-azimuthal quasi-2D simulations are performed for three operating conditions in a rather simplified representation of the thruster’s inherently 3D configuration. Nevertheless, we have resolved self-consistently an unprecedented 650 µs of the discharge evolution without any ad-hoc electron mobility model, capturing several breathing cycles and approximating the experimental performance parameters with an accuracy of 70 to 80 % across the operating conditions. The radial-azimuthal simulations, carried out at three cross-sections corresponding to different axial locations within the discharge channel, have casted further light on the evolution of the azimuthal instabilities and the resulting variations in the electrons’ cross-field mobility and the plasma-wall interactions. Particularly, we observed the development of a long-wavelength, relatively low-frequency wave mode near the exit plane of the thruster’s channel that induces a notable electron transport and a significant ion heating
Telemonitoring in chronic ventilatory failure: a new model of survellaince, a pilot study
Background and Aim. The efficiency of tele-monitoring or tele-assistance in patients with severe chronic ventilatory failure in home mechanical ventilation (HMV) is still being investigated. Our aim was to test the feasibility of a model which consisted in: 1) once a week nocturnal telemonitoring, supervised by a doctor in charge in a Respiratory Intensive Care Unit, who also provided a telephone-counselling (24/7) on demand; 2) a scheduled visit every two months. Methods. A 2-year observational study was carried out on 16 patients ventilated for at least 1 year and for ≥ 8 hours /day. Once a week patients underwent a nocturnal monitoring during HMV. The compliance was evaluated by regular transmission of data and regular follow-up, the level of satisfaction by a telephonequestionnaire. Results. The adherence to the protocol study was good in 9/16 (56%) and poor in 7/16 (44%) patients. For each patient, the mean number of connections was 46,12 ± 36.39 (70.7% of that expected), in those with good compliance it increased to 63.8 ± 32.7 (114% of that expected). The median hours of connection was 343 (138- 1019) and 89 (0-521) for patients with good and poor compliance respectively, p=0.038. The mean scheduled visits for patient with good compliance was 6.9 ± 4.14 (100% of that expected). Emergency visits were avoided in 62.5% of cases. The satisfaction score was higher in compliant versus non compliant patients (p=0.019). Conclusion. This pilot study showed that the telemonitoring system employed was feasible and effective in more compliant patients who claimed a high rate of satisfaction
Diabetic foot infections: a team-oriented review of medical and surgical management
As the domestic and international incidence of diabetes and metabolic syndrome continues to rise, health care providers need to continue improving management of the long-term complications of the disease. Emergency department visits and hospital admissions for diabetic foot infections are increasingly commonplace, and a like-minded multidisciplinary team approach is needed to optimize patient care. Early recognition of severe infections, medical stabilization, appropriate antibiotic selection, early surgical intervention, and strategic plans for delayed reconstruction are crucial components of managing diabetic foot infections. The authors review initial medical and surgical management and staged surgical reconstruction of diabetic foot infections in the inpatient setting
Mars- plus Europa-INPPS Flagship Missions with High Power Electric Thrusters and Heavy Science Payload
2020/2021 orbit calculations (DLR Bremen + MAI Moscow):
3 Orbits for one non-human MARS/EUROPA-INPPS flagship
1. Orbit Earth (11 Oct 2026) => Mars (28 Jan 2028);
2. Orbit Mars (22 Sept 2028) => Earth (29 Jul 2029);
3. Orbit Earth (12 Oct 2031) => Jupiter / Europa (6 Dec 2035)
22 ETs (for the INPPS flagship CET): example - gridded CET plate with combined ET
Reliability of ultrasound measurement of automatic activity of the abdominal muscle in participants with and without chronic low back pain
Non-Human + Human Deep Space Exploration: By The NEP INPPS Flagship
INPPS Flagship Structure & Subsystems, Ground Based Tests, Pure NEP, International Electric Thrusters, Humans Internationally To Mar
Humans to Mars: by MARS- plus EUROPA-INPPS Flagship Mission
The first non-human INPPS (International Nuclear Power and Propulsion System) flagship flight with orbits Earth-Mars-Earth-Jupiter/Europa (after 2025) is the most maximal space qualification test of INPPS flagship to carry out the second INPPS flagship flight to Mars with humans (in the 2030th). This high power space transportation tug is realistic because of A) the successful finalization of the European-Russian DEMOCRITOS
and MEGAHIT projects with their three concepts of space, ground and nuclear demonstrators for INPPS realization (reached in 2017), B) the successful ground based test of the Russian nuclear reactor with 1MWel plus important heat dissipation solution via droplet radiators (confirmed in 2018), C) the space qualification of the Russian reactor by 2025 and D) the perfect celestial constellation for a Earth-Mars/Phobos-Earth-Jupiter/Europa trajectory between 2026 and 2035.
Therefore the talk sketches the preparation status of INPPS flagship with its subsystems. Critical performance will be studied by parallel realizations of the ground and nuclear demonstrators of DEMOCRITOS (until 2025). The space qualification of INPPS with all subsystems including the nuclear reactor in the middle of
the 2020th plus the INPPS tests for about one to two years - first in high Earth orbit robotic assembly phase of INPPS and later extended in nearby Earth space environment flight - means a complete concepts driven approval for all applied INPPS space subsystem technologies.
It is also important to consider wider aspects for the overall mission implementation phase. Component like the nuclear reactor as the power source for the propulsion system will have to agree with the 1992 UN principles relevant to the use of nuclear power sources (NPS) in outer space. Therefore this talk will look into the legal and policy issues of nuclear space systems related to the international realization of mission design,
requirements of associated safety regulations (including AI applications in the subsystems) and new aspects for
INPPS flagship commercialization and new media communication on board
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