Method for simulating the performance of a boundary layer ingesting propulsion system at design and off-design

Boundary layer ingestion has emerged as a potential propulsion concept on novel aircraft configurations for the future. As these concepts progress, preliminary design tools are required that enable the simulation of these aircraft and the rapid analysis of multiple configurations. Simulation tools for boundary layer ingesting propulsion systems tend to focus on proving performance benefits at design point. However, the simulation of aircraft configurations that utilise boundary layer ingestion requires a method to simulate the propulsion system at a range of flight conditions other than design point. A tool is therefore required to enable simulations at off-design. This research presents a work flow to simulate a boundary layer ingesting propulsion system at design and off-design. The process is intended as a tool for design space exploration and the rapid analysis of concepts at the conceptualisation phase. Boundary layer calculations have been combined with conventional 1-D gas turbine performance methods to predict performance of a propulsion system at design point. This method is then extended to enable simulations at off-design conditions for a range of flight conditions or propulsion system power settings. The formulation provides a thrust-drag representation that supports conventional aircraft simulation tools. A case study of an aircraft configuration which utilises an array of boundary layer ingesting propulsors is used to demonstrate the process. The performance of individual propulsors in the array is compared at off-design. Simulations found that, although each propulsor was sized for the same propulsive force at design point, off-design performance diverged depending on operating conditions. In addition, the performance of the propulsor array as a whole was predicted as a function of altitude and Mach number. The case study is used to draw general conclusions on the performance characteristics of a boundary layer ingesting propulsor

Deep inferior epigastric perforator (DIEP) flap: Impact of drain free donor abdominal site on long term patient outcomes and duration of inpatient stay

Background: The deep inferior epigastric perforator (DIEP) flap is widely regarded as the Gold Standard in autologous breast reconstruction. Although drain-free abdominoplasty is performed in many centres, there is a paucity of evidence comparing outcomes when applied to DIEP breast reconstruction. Method: A retrospective review of patients who underwent DIEP breast reconstruction without abdominal drain insertion at Royal Free Hospital between Jan 2012-Nov 2016 was undertaken. Results were compared to previously published data from our centre on patients undergoing DIEP breast reconstruction with abdominal drains between Jan 2011-Jul 2012. Results: Thirty-five patients underwent abdominal drain-free reconstruction (GroupA). Of 74 patients who previously underwent reconstruction with abdominal drains, 33 patients underwent drain removal by postoperative day (POD)3 regardless of output (GroupB) and 41 underwent drain removal after POD3 following instructions on drainage volume/24 h (GroupC). There was no significant difference in the length of stay between patients in Group A and B (3.6 vs. 3.9 days; p = 0.204). Length of stay in Group C was significantly higher than Group A and B (p = 0.001, p = 0.001). There were no statistically significant differences in total (11.43% vs. 12.12% vs 17.07%, p = 0.780) or specific complications: Seroma: 2.86% vs. 0% vs. 4.88% (p = 0.774); Wound dehiscence: 8.57% vs. 9.09% vs. 4.88% (p = 0.728); Haematoma: 0% vs. 3.00% vs. 7.32% (p = 0.316) between Groups A, B and C, respectively. Conclusion: Our data suggests that drain-free abdominal closure in DIEP reconstruction can be safely achieved without increased postoperative complications. These conclusions support existing evidence on the use of a drain-free approach in cosmetic abdominoplasty

Defective monocyte-derived macrophage phagocytosis is associated with exacerbation frequency in COPD

Background Lower airway bacterial colonisation (LABC) in COPD patients is associated with increased exacerbation frequency and faster lung function decline. Defective macrophage phagocytosis in COPD drives inflammation, but how defective macrophage function contributes to exacerbations is not clear. This study investigated the association between macrophage phagocytosis and exacerbation frequency, LABC and clinical parameters. Methods Monocyte-derived macrophages (MDM) were generated from 92 stable COPD patients, and at the onset of exacerbation in 39 patients. Macrophages were exposed to fluorescently labelled Haemophilus influenzae or Streptococcus pneumoniae for 4 h, then phagocytosis measured by fluorimetry and cytokine release by ELISA. Sputum bacterial colonisation was measured by PCR. Results Phagocytosis of H. influenzae was negatively correlated with exacerbation frequency (r = 0.440, p < 0.01), and was significantly reduced in frequent vs. infrequent exacerbators (1.9 × 103 RFU vs. 2.5 × 103 RFU, p < 0.01). There was no correlation for S. pneumoniae. There was no association between phagocytosis of either bacteria with age, lung function, smoking history or treatment with inhaled corticosteroids, or long-acting bronchodilators. Phagocytosis was not altered during an exacerbation, or in the 2 weeks post-exacerbation. In response to phagocytosis, MDM from exacerbating patients showed increased release of CXCL-8 (p < 0.001) and TNFα (p < 0.01) compared to stable state. Conclusion Impaired COPD macrophage phagocytosis of H. influenzae, but not S. pneumoniae is associated with exacerbation frequency, resulting in pro-inflammatory macrophages that may contribute to disease progression. Targeting these frequent exacerbators with drugs that improve macrophage phagocytosis may prove beneficial

An app based on cooperative learning for the detection of danger points and the prevention of risk areas in a city

This article gives a general review of the presence of crime in today’s society, its impact in the daily life of the citizens and proposes the use of Safe Paths, a mobile application focused on risk prevention based on social collaboration and cooperative learning to identify dangerous areas and give alerts based on their users’ location and the risks around to them. It also describes some technical aspects of Safe Paths such as its architecture from the MVC approach; the use cases and actors involved in said application and finally shows its graphical user interface

Decoupling of a Current-Biased Intrinsic Josephson Junction from its Environment

We have observed a dissipative phase diffusion branch in arrays of hysteretic high-Tc intrinsic Josephson junctions. By comparing the data with a thermal activation model we extract the impedance seen by the junction in which phase diffusion is occurring. At the plasma frequency this junction is isolated from its environment and it sees its own large (~ kilo Ohm) impedance. Our results suggest that stacks of Josephson junctions may be used for isolation purposes in the development of a solid state quantum computer

Rise time evaluation of the heat flux microsensor (HFM) on a hot-air-gun test rig

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Investigating the heat transfer inside internal combustion engines is key in the search for higher efficiency, higher power output and lower emissions. To understand the process and to validate model predictions, heat flux measurements inside an engine have to be conducted. In previous works, we have always used a commercially available thermopile to measure the heat transfer in a hydrogen combustion engine, but its large dimensions pose concerns about the sensor’s response time. Therefore, measurements have been done on a calibration rig with a hot air flow as heat source. This paper presents a comparison of the rise time of the thermopile with that of an alternative sensor developed for heat transfer measurements in gas turbines. The papers results in an increased confidence in the thermopile sensor, because its response time is at least as good as that of the alternative sensor. The results do show that the reproducibility of the test rig can be improved. Moreover, due to fluctuations in the heat flux level generated by the source, only the order of magnitude of the measured heat flux of two different experiments was comparable. Therefore, a new calibration rig will be developed to improve the reproducibility and to increase stability of the heat flux level of the heat source.mp201