Techsburg (United States)

Introduction and Objective: Continuous glucose monitoring (CGM) has been associated with improved glycemic outcomes in older patients with Diabetes Mellitus (DM). Older patients may face barriers to use including challenges with technology. We are not aware of any comparison between older and younger adults. We studied if older age is associated with less favorable CGM metrics. Methods: We collected data from a CGM web-based interface, including patients with DM who had sensors active ≥ 70% of time. A total of 579 patients < 65 years (mean age=49.4 (SD=11.4) years) and 331 patients ≥ 65 years (mean age = 72.6 (SD=6.31) years) met inclusion criteria. Two sample t-tests compared % time in range, % time above range, and % time below range between the two age groups. Results: Patients ≥ 65 years showed better glycemic control when compared to patients < 65 years for % time in range and % time above range. Data was further stratified by decade of age. An ANOVA analysis showed an effect in % time in range (F(6, 903) = 3.02, p = 0.006, Eta2 = 0.02) between groups. A Tukey’s HSD post-hoc test revealed patients < 30 years and patients in their 70’s were the solitary paired age group with a statistically significant difference (p = 0.014). Conclusion: These results indicate that older patients have superior metrics when using CGM devices, when compared to younger patients. Age alone is not a predictor for worse CGM outcomes. Disclosure A. Behnke: None. A. Edwards: None. Y.R. Sterrett: None. R. Sharma: None.

Abstract A simulation approach was established for the application of lattice-Boltzmann method (LBM) CFD to low pressure turbine (LPT) aerodynamics for 2.5D linear cascades of LPT airfoils at low Reynolds numbers. This methodology was evaluated for six LPT airfoil geometries developed at AFRL (four high-lift, two high-lift/high-work) over realistic Reynolds lapse ranges. Predicted loss, loading, and suction surface boundary layer state were compared against prior linear cascade wind tunnel measurements acquired in the AFRL Low Speed Wind Tunnel Facility. The chief computational strategy for the LBM simulations was to achieve direct numerical simulation (DNS)-level fidelity across the Reynolds range using LBM-LES, as implemented in the PowerFLOW® commercial solver developed by Dassault Systèmes SIMULIA Corporation. This DNS-level fidelity was achieved by maintaining isotropically-fine near-wall grid spacing (x+,¯ y+,¯ z+¯<1) across the Reynolds number range, and was demonstrated with a grid sensitivity study and the calculation of established grid resolution quality metrics for scale-resolving simulations. Recent enhancements to PowerFLOW®’s subgrid turbulence model were leveraged to achieve accurate predictions of laminar separation/reattachment. Particular attention was paid to capturing the sensitivity of LPT airfoil cascade performance to freestream turbulence, accomplished via the introduction of resolved turbulence at the inlet of the LBM computational domain. Despite the DNS-level fidelity that was achieved, overall computational cost was compatible with industrial LPT airfoil design cycles, owing to careful scaling of the 2.5D span and simulation physical time as a function of Reynolds number. Several challenges were identified, including the occurrence of Reynolds lapse hysteresis for certain airfoils and relatively higher computational cost at the highest Reynolds numbers studied.

Abstract Complex turning vanes are commonly implemented within advanced turbomachinery systems used to mitigate or generate secondary velocity distortion for ground testing aircraft engines or fan rigs. The vanes generate large-scale vortex structures at the trailing edge region which shed and convect downstream to the neighboring stages and components. This process, known as trailing edge vortex shedding, can induce unwanted vibrations and performance losses if not accurately characterized during design phases. The current work aims to evaluate a hybrid Reynolds-Averaged Navier-Stokes (RANS) and large eddy simulation (LES) turbulence model in the prediction of trailing edge vortex shedding from StreamVane distortion generators at Reynolds numbers on the order of 105. The results are directly compared to unsteady RANS predictions and time-resolved particle image velocimetry measurements acquired in previous studies. The comparisons reveal significant qualitative differences between the large-scale wake structures due to the resolved integral scales of the hybrid model. For certain vane configurations containing highly unstable wake flows in the spanwise direction, the hybrid model improved the shedding frequency predictions by more than 11%. However, the hybrid model only marginally improved the frequency predictions by 0.4% for more stable, albeit more complex, wake flows.

Abstract StreamVane devices consist of a custom designed complex vane pack that is used to produce inlet swirl distortion for fan tests, compressor tests, and ground testing of jet engines. Due to being placed upstream of these expensive test rigs, their structural integrity is very important. Since very little research has been conducted on flutter of complex vane packs like StreamVanes, this work focused on examining flutter of one of these models in more detail as well as studying the effects of various parameters on the critical flutter speed and frequency of these devices. For this study, a quad swirl StreamVane that was previously experimentally found to flutter was further analyzed using unsteady CFD with periodic mesh deformation based off the mode shape. This showed the flow in the passage between the fluttering vanes switching between a choked state and a subsonic state as the vanes moved together and apart from each other. This initial quad swirl model was then used as the basis for a series of small-scale flutter tests. These tests examined multiple parameters including chord length, vane thickness, blockage effects, and turning angle variation. To further analyze any potential causes of the excitation, oil flow visualization was conducted and found to show some leading-edge separation and minor corner separation but no pattern to indicate these flow features are responsible for the unsteady loading driving flutter. The results in this paper provide insight into the flutter behavior of these complex vane packs.

Invasive species are one of the greatest economic and ecological threats to agriculture and natural areas in the US and the world. Among the available management tools, biological control provides one of the most economical and long-term effective strategies for managing widespread and damaging invasive species populations of nearly all taxa. However, integrating biological control programs in a more complete integrated pest management approach that utilizes increased information and communication, post-release monitoring, adaptive management practices, long-term stewardship strategies, and new and innovative ecological and genetic technologies can greatly improve the effectiveness of biological control. In addition, expanding partnerships among relevant national, regional, and local agencies, as well as academic scientists and land managers, offers far greater opportunities for long-term success in the suppression of established invasive species. In this paper we direct our recommendations to federal agencies that oversee, fund, conduct research, and develop classical biological control programs for invasive species. By incorporating these recommendations into adaptive management strategies, private and public land managers will have far greater opportunities for long-term success in suppression of established invasive species. © 2016 Society of Chemical Industry.

Obstructive sleep apnea (OSA) is characterized by repetitive collapse of the upper airway during sleep with intermittent hypoxia, hypercapnia, and stressful arousals to re-establish breathing. OSA also causes persistent sympathetic activation which contributes to the pathogenesis of hypertension (HTN). The exercise test is an established diagnostic and prognostic tool in clinical cardiology, but its utility in risk assessment for OSA has received little attention. PURPOSE: To evaluate whether cardiovascular responses to exercise testing and post-exercise recovery are altered in overweight young men with OSA. METHODS: Fourteen overweight men (BMI: Mean + SD = 32.0 + 3.7, age = 22.4 + 2.8 yr) with OSA determined via unattended polysomnography screening (Embletta pds; Embla, Broomfield, CO), 16 men without OSA (BMI = 31.4 + 3.7, age = 21.4 + 2.6), and 14 normal weight controls (BMI = 22.0+ 1.3, age 21.4+ 2.1) performed maximal cycle ergometry tests utilizing a 15 watts/min ramp. Exercise measurements included heart rate (HR), blood pressure (BP), and oxygen consumption (VO2). Recovery HR data were converted to a HR difference (i.e., HRpeak - HR 1-min recovery), and BP data converted to a recovery ratio for each minute. RESULTS: While relative VO2 did not differ between the two overweight groups at any level of exercise, values were higher in the normal weight group at all exercise intensities (repeated measures ANOVA; p < 0.05). However, when these results were adjusted for lean body mass, none of the groups differed in the VO2 response to exercise. During exercise, no group differences were noted in the HR or BP responses at any intensity. In contrast, post-exercise HR recovery was attenuated in the OSA group through minutes 1–5 (p = 0.009). BP recovery did not differ between groups. CONCLUSIONS: OSA is associated with attenuated HR recovery in young men following maximal exercise testing. This may indicate an imbalance in autonomic regulation of HR and provide an early clinical sign of OSA. Results suggest that, for young overweight men, the clinical exercise test may be helpful for risk stratification and patient selection for diagnostic testing with polysomnography. Supported by a grant from ResMed Sleep Disordered Breathing Foundation, Poway, CA. Additional support provided by Sensormedics, Yorba Linda, CA.

An acoustic-based technique to non-invasively monitor rotor blade vibrations in a gas turbine aero-engine while in operation was investigated. This technique was pursued as an alternative to traditional approaches that measure rotor blade vibration using tip-timing approaches via non-contact probes in the engine casing. Analytic acoustic modeling efforts were performed to assist in the design of a microphone array signal processing approach for sensing rotor blade vibrations. Experiments were performed in a test compressor rig equipped with on-blade strain gauges in order to test this approach in a realistic turbo machinery environment. This sensing approach experimentally demonstrated the capability to detect large-amplitude vibrations during transient rotor speed sweep tests at subsonic rotor tip Mach numbers and where the rotor blade vibration modal density was low.

Analytical approaches were developed for modeling shock wave train propagation in a one dimensional duct with wall discontinuities. This modeling approach was developed primarily for the design and analysis of non-uniformities on inlet liners of high bypass ratio turbofan engines to mitigate the radiated buzz-saw noise. The presence of non-uniformities on the surface of acoustic liners always leads to reflection of acoustic energy back towards the fan which makes the problem more complex than that of progressive shock propagation. Two analytical techniques were investigated for modeling the compound shock wave propagation to include the resulting wave interaction, namely the perturbation expansion techniques referred to as the method of strained coordinates and the method of multiple scales. The technique based on the method of strained coordinates has been more fully developed into a robust method of predicting shock propagation in a duct with wall discontinuities. A shock wave train propagation test bed was also fabricated and operated in order to validate the shock propagation model. This test bed produced shocked sound wave trains between 3 and 4 meters downstream of the acoustic compression drivers with fundamental harmonic sound pressure levels of up to 152 dB at a distance of 4 meters downstream of the sources. The model based on strained coordinates predicted shock waves that were transmitted beyond the duct discontinuities accurate to within 1.5 dB SPL at the fundamental frequency as compared to experimental measurements.