689 research outputs found

    Design and Validation of an Autonomous Mission Manager towards Coordinated Multi-Spacecraft Missions

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    For ambitious upcoming aerospace missions, autonomy will play a crucial role in achieving complex mission goals and reducing the burden for ground operations. Standalone spacecraft can leverage autonomy concepts to optimize data collection and ensure robust operation. For spacecraft clusters, autonomy can additionally provide a feasible method of ensuring coordination through onboard peer-to-peer scheduling. However, in exchange for providing flexible mission capabilities and operational convenience, autonomy introduces additional uncertainty and software complexity, which complicates the mission assurance process. This research presents a framework for designing and testing schedules consisting of heavily constrained tasks. The core of this framework, the Schedule Manager (SM), manages tasks by associating constraints with each task including time windows, task priority, conflict categories, and resource requirements, which assures that tasks will only run when capable. This increased control over individual tasks also improves the modularity of the overall mission plan, and provides a built-in fail-safe in the event of unexpected task failure through the loading of predefined contingency schedules. The SM can use estimated task durations and resource requirements to simulate schedules ahead of time, which can be used on the ground for schedule validation and onboard as a method of prognostics and to calculate resource availability windows. The ability to predict availability windows onboard and dynamically adjust depending upon currently scheduled tasks enables peer-to-peer tasking and scheduling. For example, a spacecraft can schedule a coordinated action by broadcasting the task requirements in an availability window request to all applicable spacecraft. Then, based upon the availability windows received from each spacecraft, the coordinating spacecraft can then issue a final task scheduling command with a much lower probability of conflict. The SM has been integrated with the core Flight System (cFS) from NASA, which has flight heritage on previous successful large-scale missions such as the Lunar and Dust Environment Explorer (LADEE). This integration is in the form of a cFS application called the cFS Schedule Manager (CSM), which will manage the operations for the Space Test Program Houston 7 Configurable and Autonomous Sensor Processing Research (STP-H7-CASPR) experiment that is planned for launch on SpaceX-24 to the International SpaceStation (ISS) in December 2021. Software validation was achieved with cFS unit tests, functional tests, and code analysis tools. Demonstrations were built using the COSMOS ground station and the 42 spacecraft simulator, and these were tested with a cluster of development boards in the loop as representative flight hardware

    Autonomy Operating System for UAVs: Pilot-in-a-Box

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    The Autonomy Operating System (AOS) is an open flight software platform with Artificial Intelligence for smart UAVs. It is built to be extendable with new apps, similar to smartphones, to enable an expanding set of missions and capabilities. AOS has as its foundations NASAs core flight executive and core flight software (cFEcFS). Pilot-in-a-Box (PIB) is an expanding collection of interacting AOS apps that provide the knowledge and intelligence onboard a UAV to safely and autonomously fly in the National Air Space, eventually without a remote human ground crew. Longer-term, the goal of PIB is to provide the capability for pilotless air vehicles such as air taxis that will be key for new transportation concepts such as mobility-on-demand. PIB provides the procedural knowledge, situational awareness, and anticipatory planning (thinking ahead of the plane) that comprises pilot competencies. These competencies together with a natural language interface will enable Pilot-in-a-Box to dialogue directly with Air Traffic Management from takeoff through landing. This paper describes the overall AOS architecture, Artificial Intelligence reasoning engines, Pilot-in-a-box competencies, and selected experimental flight tests to date

    Mathematical modelling of a wave-energy converter

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    Older, Heavier, Arthritic, Psychiatrically Disordered, and Opioid-Familiar Patients Are at Risk for Opioid Use After Medial Patellofemoral Ligament Reconstruction

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    Purpose: To investigate which factors predispose patients for prolonged opioid use after medial patellofemoral ligament (MPFL) reconstruction. Methods: A retrospective review of all patients who underwent MPFL reconstruction at a single institution between January 2013 and June 2020 was conducted. Opioid consumption before and after surgery was recorded and confirmed using Michigan Automated Prescriptions System monitoring program. Patients were classified into preoperative opioid users and nonusers. Risk factors for continued opioid use were assessed by collecting patient demographic variables, psychiatric history, number of previous patellar dislocations, and operative factors. Results: A total of 102 patients were included during the time frame of interest. Patients were on average 21.6 ± 8.5 years old with a mean body mass index of 28.2 ± 7.9. Thirty patients (29.0%) sustained \u3e10 dislocations preoperatively. Preoperative opioid use was present in 13 (12.7%) patients. Greater than 10 dislocations (odds ratio [OR] 5.00, 95% confidence interval [CI] 1.12-20.92) and psychiatric history (OR 3.33, 95% CI, 1.2-9.1; P = .016) significantly predicted opioid refills the first month after surgery. Risk factors for opioid refills at 2 to 12 months postoperatively included smoking (OR 4.50, 95% CI 1.13-17.96), preoperative opioid use (OR 7.32, 95% CI 1.88-28.47), psychiatric disorder (OR 3.77, 95% CI 2.3-6.2; P \u3c .001), age \u3e30 years (OR 7.03, 95% CI 3.63-13.61; P \u3c .001), and obesity (OR 2.68, 95% CI 1.40-5.14; P = .002). Compared with Outerbridge 0, a greater percentage of patients with Outerbridge 1 or 2 and 3 or 4 continued using opioids 2 to 12 months after surgery (OR 3.06, 95% CI 1.33-7.02; P = .006 and OR 2.86, 95% CI 1.24-6.59; P = .010, respectively). Conclusions: For patients undergoing MPFL reconstruction, preoperative opioid use, cartilage damage, age \u3e30 years, smoking history, body mass index \u3e30, and history of psychiatric disorder were found to be significantly associated with prolonged opioid use after surgery. Postoperative opioid refills in this cohort declined after 1 month. Level of Evidence: Level III, retrospective cohort study

    Lower Extremity Injury After Return to Sports From Concussion: A Systematic Review

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    BACKGROUND: Recent studies have suggested increased rates of lower extremity (LE) musculoskeletal injury after a diagnosed concussion, although significant heterogeneity exists. PURPOSE: To examine the current body of research and determine whether there is an increased risk for LE musculoskeletal injury after a concussion and to identify populations at an increased risk. STUDY DESIGN: Systematic review; Level of evidence, 3. METHODS: A systematic review of current literature using MEDLINE and PubMed databases was performed. Keywords included concussion, athlete, lower extremity injury, and return to sport. Inclusion criteria required original research articles written in the English language examining the rate of LE injuries after a diagnosed concussion. RESULTS: A total of 13 studies involving 4349 athletes (88.1% male and 11.9% female; mean age, 19.8 years) met inclusion criteria. Athletes were classified as high school (46.1%), collegiate (17.0%), or professional (36.9%). Of the 13 studies, 4 demonstrated an increased risk of LE injury within 90 days of a diagnosed concussion (odds ratio [OR], 3.44; 95% CI, 2.99-4.42), and 6 revealed an elevated risk of injury within 1 year of concussion (OR, 1.85; 95% CI, 1.73-2.84). Increased risk was seen in professional (OR, 2.49; 95% CI, 2.40-2.72) and collegiate (OR, 2.00; 95% CI, 1.96-2.16) athletes compared with high school athletes (OR, 0.97; 95% CI, 0.89-1.05). A stepwise increase in risk of sustaining an LE injury was observed with multiple concussions, with increasing risk observed from ≥2 (OR, 2.29; 95% CI, 1.85-2.83) to ≥3 (OR, 2.86; 95% CI, 2.36-3.48) career concussions. CONCLUSION: An increased incidence of LE injuries was observed at 90 days and 1 year after the diagnosis of a concussion. Higher levels of competition, such as at the collegiate and professional levels, resulted in an increased risk of sustaining a subsequent LE injury after a diagnosed concussion. These results suggest an at-risk population who may benefit from injury prevention methods after a concussion. Future studies should focus on identifying which injuries are most common, during what time period athletes are most vulnerable, and methods to prevent injury after return to sports

    MIPModDB: a central resource for the superfamily of major intrinsic proteins

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    The channel proteins belonging to the major intrinsic proteins (MIP) superfamily are diverse and are found in all forms of life. Water-transporting aquaporin and glycerol-specific aquaglyceroporin are the prototype members of the MIP superfamily. MIPs have also been shown to transport other neutral molecules and gases across the membrane. They have internal homology and possess conserved sequence motifs. By analyzing a large number of publicly available genome sequences, we have identified more than 1000 MIPs from diverse organisms. We have developed a database MIPModDB which will be a unified resource for all MIPs. For each MIP entry, this database contains information about the source, gene structure, sequence features, substitutions in the conserved NPA motifs, structural model, the residues forming the selectivity filter and channel radius profile. For selected set of MIPs, it is possible to derive structure-based sequence alignment and evolutionary relationship. Sequences and structures of selected MIPs can be downloaded from MIPModDB database which is freely available at http://bioinfo.iitk.ac.in/MIPModDB

    Barriers for introducing HIV testing among tuberculosis patients in Jogjakarta, Indonesia: a qualitative study

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    <p>Abstract</p> <p>Background</p> <p>HIV and HIV-TB co-infection are slowly increasing in Indonesia. WHO recommends HIV testing among TB patients as a key response to the dual HIV-TB epidemic. Concerns over potential negative impacts to TB control and lack of operational clarity have hindered progress. We investigated the barriers and opportunities for introducing HIV testing perceived by TB patients and providers in Jogjakarta, Indonesia.</p> <p>Methods</p> <p>We offered Voluntary Counselling and Testing (VCT) to TB patients in parallel to a HIV prevalence survey. We conducted in-depth interviews with 33 TB patients, 3 specialist physicians and 3 disease control managers. We also conducted 4 Focus Group Discussions (FGDs) with nurses. All interviews and FGDs were recorded and data analysis was supported by the QSR N6<sup>® </sup>software.</p> <p>Results</p> <p>Patients' and providers' knowledge regarding HIV was poor. The main barriers perceived by patients were: burden for accessing VCT and fear of knowing the test results. Stigma caused concerns among providers, but did not play much role in patients' attitude towards VCT. The main barriers perceived by providers were communication, patients feeling offended, stigmatization and additional burden.</p> <p>Conclusion</p> <p>Introduction of HIV testing among TB patients in Indonesia should be accompanied by patient and provider education as well as providing conditions for effective communication.</p
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