606 research outputs found
Time domain modal identification/estimation of the mini-mast testbed
The Mini-Mast is a 20 meter long 3-dimensional, deployable/retractable truss structure designed to imitate future trusses in space. Presented here are results from a robust (with respect to measurement noise sensitivity), time domain, modal identification technique for identifying the modal properties of the Mini-Mast structure even in the face of noisy environments. Three testing/analysis procedures are considered: sinusoidal excitation near resonant frequencies of the Mini-Mast, frequency response function averaging of several modal tests, and random input excitation with a free response period
SmartTrack: Efficient Predictive Race Detection
Widely used data race detectors, including the state-of-the-art FastTrack
algorithm, incur performance costs that are acceptable for regular in-house
testing, but miss races detectable from the analyzed execution. Predictive
analyses detect more data races in an analyzed execution than FastTrack
detects, but at significantly higher performance cost.
This paper presents SmartTrack, an algorithm that optimizes predictive race
detection analyses, including two analyses from prior work and a new analysis
introduced in this paper. SmartTrack's algorithm incorporates two main
optimizations: (1) epoch and ownership optimizations from prior work, applied
to predictive analysis for the first time; and (2) novel conflicting critical
section optimizations introduced by this paper. Our evaluation shows that
SmartTrack achieves performance competitive with FastTrack-a qualitative
improvement in the state of the art for data race detection.Comment: Extended arXiv version of PLDI 2020 paper (adds Appendices A-E) #228
SmartTrack: Efficient Predictive Race Detectio
GT2007-27862 REAL-TIME HEALTH ESTIMATION AND AUTOMATED FAULT ACCOMMODATION FOR PROPULSION SYSTEMS
ABSTRACT This paper presents the development of innovative realtime health estimation and automated fault accommodation techniques for advanced propulsion systems within a Dynamic Decision Support (D 2 S) framework. The proposed approach uses dynamic models in a real-time computing environment to not only diagnose system degradation and faults, but also to determine "on the fly" how to accommodate for them. The realtime health estimation modules enhance on-board PHM (Prognosis & Health Management) capabilities with a dynamic system identification algorithm that is capable of detecting faults with a continuously updated dynamic model. In addition, a real-time, self-tuning Kalman filter and fault classification algorithm are combined to provide accurate health estimation. Based on the inferred health condition, mission requirements and flight regime information, the automated fault accommodation module automatically makes decisions regarding control reconfiguration and change of control strategies. The presented techniques have been applied to a generic turbofan engine model with simulated engine component faults and degradation and simulation results are presented. To further raise the technological readiness level, select algorithms have been implemented and evaluated on a PC104 embedded platform. The dynamic modeling capabilities, techniques and tools sets will not only improve the reliability of the propulsion systems, but also greatly enhance maintenance decision support and contingency planning concepts
implementation of an in-house management routine
Background Coma of unknown origin is an emergency caused by a variety of
possibly life-threatening pathologies. Although lethality is high, there are
currently no generally accepted management guidelines. Methods We implemented
a new interdisciplinary standard operating procedure (SOP) for patients
presenting with non-traumatic coma of unknown origin. It includes a new in-
house triage process, a new alert call, a new composition of the clinical
response team and a new management algorithm (altogether termed “coma alarm”).
It is triggered by two simple criteria to be checked with out-of-hospital
emergency response teams before the patient arrives. A neurologist in
collaboration with an internal specialist leads the in-hospital team.
Collaboration with anaesthesiology, trauma surgery and neurosurgery is
organised along structured pathways that include standardised laboratory tests
and imaging. Patients were prospectively enrolled. We calculated response
times as well as sensitivity and false positive rates, thus proportions of
over- and undertriaged patients, as quality measures for the implementation in
the SOP. Results During 24 months after implementation, we identified 325
eligible patients. Sensitivity was 60 % initially (months 1–4), then
fluctuated between 84 and 94 % (months 5–24). Overtriage never exceeded 15 %
and undertriage could be kept low at a maximum of 11 % after a learning
period. We achieved a median door-to-CT time of 20 minutes. 85 % of patients
needed subsequent ICU treatment, 40 % of which required specialised neuro-
ICUs. Discussion Our results indicate that our new simple in-house triage
criteria may be sufficient to identify eligible patients before arrival. We
aimed at ensuring the fastest possible proceedings given high portions of
underlying time-sensitive neurological and medical pathologies while using all
available resources as purposefully as possible. Conclusions Our SOP may
provide an appropriate tool for efficient management of patients with non-
traumatic coma. Our results justify the assignment of the initial diagnostic
workup to neurologists and internal specialists in collaboration with
anaesthesiologists
Osteopotentia regulates osteoblast maturation, bone formation, and skeletal integrity in mice
A component of the rough ER, SUN domain protein osteopotentia, regulates expansion of this organelle in osteoblasts during skeletal development and regeneration
Longitudinal assessment of cyst-like lesions of the knee and their relation to radiographic osteoarthritis and MRI-detected effusion and synovitis in patients with knee pain
Introduction\ud
The purpose of the present study was to determine the prevalence of cystic lesions and cyst-like bursitides in subjects with frequent knee pain and to assess their relation to radiographic osteoarthritis (OA) severity; to describe bilaterality and size fluctuation of the lesions over 6 months; and to assess relations between the prevalence of synovium-lined lesions communicating with the joint capsule and severity of magnetic resonance imaging (MRI)-detected effusion and synovitis.\ud
\ud
Methods\ud
One hundred and sixty-three subjects (total 319 knees) aged 35 to 65 with chronic, frequent knee pain were included. Imaging with 3 Tesla MRI was performed at baseline and 6-month follow-up with the same protocols as those used in the Osteoarthritis Initiative. Severity of radiographic OA was assessed using the Kellgren-Lawrence grade (0 to 4). Severity of effusion and synovitis was graded 0 to 3 based on the Whole Organ Magnetic Resonance Imaging Score system. The associations of cysts and cyst-like bursitides and severity of radiographic OA, MRI-detected effusion and synovitis were analyzed using logistic regression controlling for clustering by person. The Wilcoxon signed-rank test was used to determine whether there was a significant change in the size of lesions between baseline and follow-up.\ud
\ud
Results\ud
At least one lesion (any type) was present in 222 (70%) knees. The most prevalent lesions were popliteal cysts (40%, 128/319), followed by subgastrocnemius bursitis (15%, 49/319) and proximal tibiofibular joint cysts (8%, 26/319). Bilateral lesions were seen in 49% of the subjects. Only popliteal cysts and subgastrocnemius bursitis showed a significant change in size (P < 0.001). No trend was observed between prevalence of any of the cyst-like lesions analyzed and the increasing radiographic OA severity. Increasing prevalence of subgastrocnemius bursitis was associated with increasing severity of effusion (P = 0.0072) and synovitis (P = 0.0033).\ud
\ud
Conclusions\ud
None of the cyst-like lesions analyzed seems to be a marker of radiographic OA severity in knees with chronic frequent pain. Subgastrocnemius bursitis may be used as a marker of effusion/synovitis severity. Bilateral cyst-like lesions are relatively commonly observed in people with chronic knee pain
Semiquantitative assessment of subchondral bone marrow edema-like lesions and subchondral cysts of the knee at 3T MRI: A comparison between intermediate-weighted fat-suppressed spin echo and Dual Echo Steady State sequences
Background\ud
Choice of appropriate MR pulse sequence is important for any research studies using imaging-derived data. The aim of this study was to compare semiquantitative assessment of subchondral bone marrow edema-like lesions and subchondral cysts using intermediate-weighted (IW) fat-suppressed (fs) spin echo and Dual Echo Steady State (DESS) sequences on 3 T MRI.\ud
\ud
Methods\ud
Included were 201 subjects aged 35-65 with frequent knee pain. 3T MRI was performed with the same sequence protocol as in the Osteoarthritis Initiative (OAI). In a primary reading subchondral bone marrow edema-like lesions were assessed according to the WORMS system. Two hundred subregions with such lesions were randomly chosen. The extent of subchondral bone marrow edema-like lesions was re-evaluated separately using sagittal IW fs and DESS sequences according to WORMS. Lesion size and confidence of the differentiation between subchondral bone marrow edema-like lesions and subchondral cysts located within or adjacent to them was rated from 0 to 3. Wilcoxon signed-rank tests and chi-square statistics were used to examine differences between the two sequences.\ud
\ud
Results\ud
Of 200 subchondral bone marrow edema-like lesions detected by IW fs sequence, 93 lesions (46.5%) were not depicted by the DESS sequence. The IW fs sequence depicted subchondral bone marrow edema-like lesions to a larger extent than DESS (p < 0.0001), and the opposite was true for subchondral cysts. Confidence scores for differentiation of the two types of lesions were not significantly different between the two sequences.\ud
\ud
Conclusions\ud
In direct comparison the IW fs sequence depicts more subchondral bone marrow edema-like lesions and better demonstrate the extent of their maximum size. The DESS sequence helps in the differentiation of subchondral bone marrow edema-like lesions and subchondral cysts. The IW fs sequence should be used for determination of lesion extent whenever the size of subchondral bone marrow edema-like lesions is the focus of attention
Mitochondrial DNA haplogroups associated with MRI-detected structural damage in early knee osteoarthritis
[Abstract] Objective: Magnetic resonance imaging (MRI)-detected structural features are associated with increased risk of radiographic osteoarthritis (ROA). Specific mitochondrial DNA (mtDNA) haplogroups have been associated with incident ROA. Our objective was to compare the presence of MRI-detected structural features across mtDNA haplogroups among knees that developed incident ROA.
Design: Knees from the Osteoarthritis Initiative (OAI) that developed incident ROA during 48 months follow-up were identified from Caucasian participants. mtDNA haplogroups were assigned based on a single base extension assay. MRIs were obtained annually between baseline and 4-year follow-up and scored using the MRI Osteoarthritis Knee Score (MOAKS). The association between mtDNA haplogroups and MRI-detected structural features was estimated using log-binomial regression. Participants who carried haplogroup H served as the reference group.
Results: The sample included 255 participants contributing 277 knees that developed ROA. Haplogroups included H (116, 45%), J (17, 7%), T (26, 10%), Uk (61, 24%), and the remaining less common haplogroups ("others") (35, 14%). Knees of participants with haplogroup J had significantly lower risk of medium/large bone marrow lesions (BMLs) in the medial compartment [3.2%, relative risks (RR) = 0.17; 95%CI: 0.05, 0.64; P = 0.009] compared to knees of participants who carried haplogroup H [16.3%], as did knees from participants within the "others" group [2.8%, RR = 0.20; 95%CI: 0.08, 0.55; P = 0.002], over the 4 year follow-up period.
Conclusions: mtDNA haplogroup J was associated with lower risk of BMLs in the medial compartment among knees that developed ROA. Our results offer a potential hypothesis to explain the mechanism underlying the previously reported protective association between haplogroup J and ROA.National Institute of Health; NIH HHSN2682010000 21CNational Institute of Health; NIH AR06660
Upgrading Engine Test Cells for Improved Troubleshooting and
Abstract Upgrading military engine test cells with advanced diagnostic and troubleshooting capabilities will play a critical role in increasing aircraft availability and test cell effectiveness while simultaneously reducing engine operating and maintenance costs. Sophisticated performance and mechanical anomaly detection and fault classification algorithms utilizing thermodynamic, statistical, and empirical engine models are now being implemented as part of a United States Air Force Advanced Test Cell Upgrade Initiative. Under this program, a comprehensive set of real-time and post-test diagnostic software modules, including sensor validation algorithms, performance fault classification techniques and vibration feature analysis are being developed. An automated troubleshooting guide is also being implemented to streamline the troubleshooting process for both inexperienced and experienced technicians. This artificial intelligence based tool enhances the conventional troubleshooting tree architecture by incorporating probability of occurrence statistics to optimize the troubleshooting path. This paper describes the development and implementation of the F404 engine test cell upgrade at the Jacksonville Naval Air Station
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