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Background: Major gaps exist in the routine initiation and dose up-titration of guideline-directed medical therapies (GDMT) for patients with heart failure with reduced ejection fraction. Without novel approaches to improve prescribing, the cumulative benefits of heart failure with reduced ejection fraction treatment will be largely unrealized. Direct-to-consumer marketing and shared decision making reflect a culture where patients are increasingly involved in treatment choices, creating opportunities for prescribing interventions that engage patients. Methods: The EPIC-HF (Electronically Delivered, Patient-Activation Tool for Intensification of Medications for Chronic Heart Failure with Reduced Ejection Fraction) trial randomized patients with heart failure with reduced ejection fraction from a diverse health system to usual care versus patient activation tools—a 3-minute video and 1-page checklist—delivered electronically 1 week before, 3 days before, and 24 hours before a cardiology clinic visit. The tools encouraged patients to work collaboratively with their clinicians to “make one positive change” in heart failure with reduced ejection fraction prescribing. The primary endpoint was the percentage of patients with GDMT medication initiations and dose intensifications from immediately preceding the cardiology clinic visit to 30 days after, compared with usual care during the same period. Results: EPIC-HF enrolled 306 patients, 290 of whom attended a clinic visit during the study period: 145 were sent the patient activation tools and 145 were controls. The median age of patients was 65 years; 29% were female, 11% were Black, 7% were Hispanic, and the median ejection fraction was 32%. Preclinic data revealed significant GDMT opportunities, with no patients on target doses of β-blocker, sacubitril/valsartan, and mineralocorticoid receptor antagonists. From immediately preceding the cardiology clinic visit to 30 days after, 49.0% in the intervention and 29.7% in the control experienced an initiation or intensification of their GDMT ( P =0.001). The majority of these changes were made at the clinician encounter itself and involved dose uptitrations. There were no deaths and no significant differences in hospitalization or emergency department visits at 30 days between groups. Conclusions: A patient activation tool delivered electronically before a cardiology clinic visit improved clinician intensification of GDMT. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03334188.

Background Heart failure with reduced ejection fraction (HFrEF) benefits from initiation and intensification of multiple pharmacotherapies. Unfortunately, there are major gaps in the routine use of these drugs. Without novel approaches to improve prescribing, the cumulative benefits of HFrEF treatment will be largely unrealized. Direct-to-consumer marketing and shared decision making reflect a culture where patients are increasingly involved in treatment choices, creating opportunities for prescribing interventions that engage patients. Hypothesis Encouraging patients to engage providers in HFrEF prescribing decisions will improve the use of guideline-directed medical therapies. Design The Electronically delivered, Patient-activation tool for Intensification of Chronic medications for Heart Failure with reduced ejection fraction (EPIC-HF) trial randomizes patients with HFrEF to usual care versus patient-activation tools—a 3-minute video and 1-page checklist—delivered prior to cardiology clinic visits that encourage patients to work collaboratively with their clinicians to intensify HFrEF prescribing. The study assesses the effectiveness of the EPIC-HF intervention to improve guideline-directed medical therapy in the month after its delivery while using an implementation design to also understand the reach, adoption, implementation, and maintenance of this approach within the context of real-world care delivery. Study enrollment was completed in January 2020, with a total 305 patients. Baseline data revealed significant opportunities, with Summary The EPIC-HF trial assesses the implementation, effectiveness, and safety of patient engagement in HFrEF prescribing decisions. If successful, the tool can be easily disseminated and may inform similar interventions for other chronic conditions.

Spacecraft in low earth orbit (LEO) experience a variety of hazards including exposure to micrometeoroids and orbital debris (MMOD). Average impact speeds for orbital debris on spacecraft in LEO are 9 to 10 km/s, and 20 km/s for micrometeoroids. Due to their high speeds, MMOD can cause considerable impact damage to sensitive spacecraft surfaces such as windows, structural elements, electronic boxes, solar arrays, radiators, thermal protection system (TPS) materials covering crew/cargo return vehicles, as well as crew modules. Prolonged exposure to the on-orbit MMOD environment can potentially compromise the TPS covering return vehicles such as the future crewed vehicles expected to visit and remain for a half-year or longer at the International Space Station (ISS). However, determination of MMOD impact damage to the TPS on crew/cargo return vehicles, or damage to other orbiting spacecraft currently requires visual inspection. For human-rated spacecraft such as the ISS and, previously, the Space Shuttle Orbiter, this has required crew time as well as vehicle assets to identify damage due to MMOD strikes. For unmanned spacecraft, there are no human assets present to conduct detailed surveys to identify potential damage. While the practice of visual inspection may successfully indicate the location of a debris strike, it does not currently allow precise determination of exactly when the debris strike occurred. It is only possible to determine that a debris strike has occurred between two successive inspection events unless damage to other components can allow inference that a debris strike occurred at a specified time. Initial development testing of a novel MMOD sensing concept amenable for potential implementation in a structural health monitoring system is discussed. Using fiber Bragg grating (FBG) sensing technology, a test article representative of a spacecraft MMOD shield layer or spacecraft structure was subjected to hypervelocity impact testing. The FBG array successfully detected that an impact had occurred, when it occurred and where it occurred on the structure. Detection of both the impact wave and the residual strain in the structure can be used to infer the location of the impact. The potential application of this technology to spacecraft is discussed.

Introduction Guideline Directed Medical Therapy (GDMT) recommends a combined regimen of beta blockers, ACE-I/ARB/ARNI, and mineralocorticoid receptor agents for optimal treatment of patients with Heart Failure with Reduced Ejection Fraction (HFrEF). Unfortunately, data from numerous heart failure registries show that HFrEF patients by-and-large continue to remain on suboptimal therapy. Interventions to improve medication plans often target either patient adherence or provider prescribing methods, with mixed results. This suggests that a more novel approach—in which provider and patient are equally involved—may be necessary to incite change. Hypothesis Aspects of Direct-to-Consumer (DTC) methods and Shared Decision Making models can be harnessed to encourage patients to engage providers in HFrEF prescribing decisions. This in turn may improve use of guideline-directed medical therapies. Methods Using DTC and Shared Decision Making models as our framework (Figure 1), we developed a user-friendly patient activation intervention—a 3-minute video and a HFrEF medication checklist—to encourage patients to discuss with their provider “one thing” that can be done to improve their medication plan. Patients were enrolled across three medical centers within the UCHealth medical system, and randomized to either intervention or control arms. Data on HFrEF medication prescribing and dosing was collected at enrollment, at time of intervention, and at 1-and-6 months from intervention. Results 305 patients were enrolled in total. At time of enrollment, 8.5% were on GDMT at suboptimal doses; only one patient (.3%) was on GDMT at target doses. Conclusions Our baseline results highlight the clear need for effective interventions to improve HFrEF prescribing. If successful, our intervention is simple enough to be adapted and implemented across a multitude of settings.

The National Aeronautics and Space Administration (NASA) Engineering and Safety Center Shell Buckling Knockdown Factor Project is a multicenter project tasked with developing new analysis-based shell buckling design guidelines and design factors (i.e., knockdown factors) through high-fidelity buckling simulations and advanced test technologies. To validate these new buckling knockdown factors for future launch vehicles, the Shell Buckling Knockdown Factor Project is carrying out structural testing on a series of large-scale metallic and composite cylindrical shells at the NASA Marshall Space Flight Center (Marshall Space Flight Center, Alabama). A fiber optic sensor system was used to measure strain on a large-scale sandwich composite cylinder that was tested under multiple axial compressive loads up to more than 850,000 lb, and equivalent bending loads over 22 million in-lb. During the structural testing of the composite cylinder, strain data were collected from optical cables containing distributed fiber Bragg gratings using a custom fiber optic sensor system interrogator developed at the NASA Armstrong Flight Research Center. A total of 16 fiber-optic strands, each containing nearly 1,000 fiber Bragg gratings, measuring strain, were installed on the inner and outer cylinder surfaces to monitor the test article global structural response through high-density real-time and post test strain measurements. The distributed sensing system provided evidence of local epoxy failure at the attachment-ring-to-barrel interface that would not have been detected with conventional instrumentation. Results from the fiber optic sensor system were used to further refine and validate structural models for buckling of the large-scale composite structures. This paper discusses the techniques employed for real-time structural monitoring of the composite cylinder for structural load introduction and distributed bending-strain measurements over a large section of the cylinder by utilizing unique sensing capabilities of fiber optic sensors.

Over the past century aircraft wing design has transformed from the morphing wing used on the Wright Flyer to rigid wings with little to no shape-tailoring abilities. Modern day wings are designed to fly at a single trim condition and optimized to have a maximum aerodynamic efficiency at only this condition. Shape morphing wings on the other hand have the potential to undergo geometric changes allowing them to adapt to their mission profiles. Several flight demonstrations have been conducted over the decades using morphing-wing technologies. Active wing-twist control was demonstrated on the X-53 Active Aeroelastic Wing (AAW) research project by utilizing multiple leading- and trailing-edge control surfaces. Passive morphing technology has been demonstrated on the Rockwell RPRV-870 Highly Maneuverable Aircraft Technology (HiMAT) aircraft. In the current study, the wings of a small unmanned aerial system (sUAS) were modified to have segmented control surfaces (SCS). The modifications include segmenting the original wing control surfaces (one flap and one aileron per wing) into 44 individual sections, each section having its own independent servo control motor. The wings were also instrumented with a network of over 1800 fiber-optic strain sensors (on four sensing fibers distributed over the top and bottom surfaces of the wing) monitoring the strain response of the wing to aerodynamic loading. The SCS positions were manipulated in real time to modify the spanwise lift distribution of the wings on the sUAS. The change in the structural response of the wings caused by load redistribution was quantified by measuring the bending strains on the upper and lower wing surfaces using an on-board compact fiber-optic strain sensing (cFOSS) system. A feedback controller was developed to control the SCS positions using strain-based shape estimations from the Displacement Transfer Function (DTF). Post-processing of the strain data allowed for the transverse displacement distributions and load distributions to be compared for the conventional and segmented control surface cases using displacements and loads algorithms developed by Richards and Ko at AFRC (refs. 5-10). While the current study focused on the shifting of the spanwise aerodynamic loads as quantified by displacements, future applications for loads or displacement control might include active gust alleviation and flutter suppression.

A new deformation shape-sensing methodology is investigated for the purposes of real-time condition assessment, control, and health monitoring of flexible lightweight aerospace structures. The fiber optic strain sensing technology was recently proposed by the NASA Dryden Flight Research Center. The methodology implements the use of fiber optic sensors to obtain strain measurements from the target structure and to estimate the corresponding displacement field. In this paper, the methodology is investigated through an experimental aluminum winglike swept-plate model. The proposed algorithm is implemented for three distinct loading cases and compared to a well-established modal-based shape-estimation algorithm. The estimation results from both methods are also compared to reference displacements from photogrammetry and computational analyses. The estimation error for each method is quantified using the root-mean-square measure, and the range of validity of the approach for damage detection is established. Fu...

The thermal protection systems of spacecraft are vulnerable to damage from impacts by foreign objects moving at high velocities. This paper describes a proposed novel structural health monitoring system that will detect, locate and evaluate the damage resulting from such impacts. This system consists of a network of intelligent local agents, each of which controls a network of piezoelectric acoustic emission sensors to detect and locate an impact, and a network of optical fibre Bragg grating sensors to evaluate the effect of the impact damage by means of a thermographic technique. The paper concentrates on two issues that are critical to the successful implementation of the proposed SHM system: measurement of the elastic properties of the thermal protection material, knowledge of which is essential to the design and operation of the acoustic emission sensor network; and investigation of the practical feasibility of a switched network of optical fibre sensors.

Background Patients with advanced peripheral vascular disease (PVD) and critical limb ischemia (CLI) require immediate revascularization to improve blood flow and prevent amputation. Vascular, and especially tibial, access is arguably a very important part of the procedure. Utilization of ultrasound (US) guidance to access the peripheral vessels will maximize success and decrease the risk of complications. Methods This is a retrospective analysis of patients admitted to our institution between 2010 and 2011. Eighty-six patients with 191 lesions underwent revascularization for advanced PVD and CLI. US guidance was utilized to access the vascular bed in an antegrade or retrograde fashion in 100% of these patients. Data collected included success rate and time to access using US. Immediate in hospital and 30 day outcomes were also documented. Results The average age of patients was 69.8 years, with 69.7% male patients. All tibial access (33.7%) was obtained under US guidance. Obtaining vascular access using US was achieved in 95.3% of patients. At discharge, access site complications were limited to one patient (1.1%) with a pseudoaneurysm; no access complications related to the tibial vessels. At 30 days, there was one major amputation (1.1%) and one vascular access complication (1.1%). Conclusion US guided access is a feasible and safe procedure that can aid in accessing vascular conduits in patients with CLI. Applying this technique across the board in CLI patients decreases the risk of immediate complications and facilitates accessing tibial arteries. © 2012 Wiley Periodicals, Inc.

The invention is a magneto-optic coupled magnetic sensor that comprises a standard optical fiber Bragg grating system. The system includes an optical fiber with at least one Bragg grating therein. The optical fiber has at least an inner core and a cladding that surrounds the inner core. The optical fiber is part of an optical system that includes an interrogation device that provides a light wave through the optical fiber and a system to determine the change in the index of refraction of the optical fiber. The cladding of the optical fiber comprises at least a portion of which is made up of ferromagnetic particles so that the ferromagnetic particles are subject to the light wave provided by the interrogation system. When a magnetic field is present, the ferromagnetic particles change the optical properties of the sensor directly.

This study investigates the influence of strain state distribution on the accuracy of embedded optical fiber Bragg gratings (FBGs) used as strain sensors. An optical fiber embedded parallel to adjacent structural fibers in a graphite epoxy quasi-isotropic [(90/+/- 45/0)(S)](3) lay-up is evaluated with mechanical loading parallel to the fiber optic direction. Finite element analysis (FEA) is used to evaluate the fiber optic sensors' responses both in the far field and near field regions of the mechanical grips. Comparison between experimental fiber optic strains, strain gauges, and FEA provides good correlation in the far field with differences of less than 1%. However, in the near field region, some discrepancies are found and attributed to birefringence arising from complex strain states.

An overview of the research and technological development of the fiber-optic sensing system (FOSS) at the National Aeronautics and Space Administration Armstrong Flight Research Center (NASA AFRC) is presented. Theory behind fiber Bragg grating (FBG) sensors, as well as interrogation technique based on optical frequency domain reflectometry (OFDR) is discussed. Assessment and validation of FOSS as an accurate measurement tool for structural health monitoring is realized in the laboratory environment as well as large-scale flight deployment.

A 2015 NASA Aeronautics Mission "Seedling" Proposal is described for a Severe-Environment UAV (SE-UAV) that can perform in-situ measurements in hazardous atmospheric conditions like lightning, volcanic ash and radiation. Specifically, this paper describes the design of a proof-of-concept vehicle and measurement system that can survive lightning attachment during flight operations into thunderstorms. Elements from three NASA centers draw together for the SE-UAV concept. 1) The NASA KSC Genesis UAV was developed in collaboration with the DARPA Nimbus program to measure electric field and X-rays present within thunderstorms. 2) A novel NASA LaRC fiber-optic sensor uses Faraday-effect polarization rotation to measure total lightning electric current on an air vehicle fuselage. 3) NASA AFRC's state-of-the-art Fiber Optics and Systems Integration Laboratory is envisioned to transition the Faraday system to a compact, light-weight, all-fiber design. The SE-UAV will provide in-flight lightning electric-current return stroke and recoil leader data, and serve as a platform for development of emerging sensors and new missions into hazardous environments. NASA's Aeronautics and Science Missions are interested in a capability to perform in-situ volcanic plume measurements and long-endurance UAV operations in various weather conditions. (Figure 1 shows an artist concept of a SE-UAV flying near a volcano.) This paper concludes with an overview of the NASA Aeronautics Strategic Vision, Programs, and how a SE-UAV is envisioned to impact them. The SE-UAV concept leverages high-value legacy research products into a new capability for NASA to fly a pathfinder UAV into hazardous conditions, and is presented in the SPIE DSS venue to explore teaming, collaboration and advocacy opportunities outside NASA.

Background Hospital bed handsets, including nurse call equipment and television controls, have been found to contain biologic material and may be contaminated with microbes. Objective The aim of this study was to assess the microbial contamination of hospital bed handsets. Methods Hospital bed handsets were removed from 115 randomly chosen rooms in a suburban hospital. The handsets were transported to the laboratory in a sterile fashion and opened using a sterile technique, and cultures were obtained from both the anterior and posterior surfaces of the units. Results The cultures of 12 units (10.4%) revealed no microorganisms. One hundred three units (89.6%) had cultures that grew microorganisms. Of the handsets that were found to contain microorganisms, 48 units (46.6%) had only 1 microorganism, and 55 units (53.4%) had multiple organisms, including 33 units (32.0%) with 2 microorganisms, 21 units (20.4%) with 3 microorganisms, and 1 unit (1.0%) with 4 microorganisms. The microorganisms identified included 90 isolates (87.4%) of coagulase-negative staphylococcus, 51 isolates (49.5%) of bacillus species, 13 isolates (12.6%) of fungal species, 8 isolates (7.8%) of nonhemolytic streptococcus species, 7 isolates (6.8%) of α-hemolytic streptococcus species, 1 isolate (1.0%) of Staphylococcus aureus , and 1 isolate (1.0%) of methicillin-resistant Staphylococcus aureus . Conclusion Hospital bed handsets were found to have a high incidence of contamination with bacteria and fungus and were found to contain organisms that are known to be the etiologic agents in nosocomial infections. Because of the frequency and duration of contact between hospital patients and hospital bed handsets, existing infection control measures should be studied that could reduce the level of contamination of such handsets or that could isolate the handsets from the patient.

A thermal health monitoring technique is investigated based on thermography that uses optical fiber thermal sensors to detect damage within a laminated graphite epoxy composite specimen. Composite samples manufactured for testing have fiber optic sensors embedded between the layers while thermocouples are attached to the exteriors for verification. Teflon inserts are used to simulate delaminations and the sensitivity range of the embedded sensors is determined. A numerical model is developed to confirm the experimental findings and establish optimum sensor placement. Results indicate that this technique can detect down to a 20-mm delamination, possibly smaller. In addition, the sensors can typically locate a delamination up to 17 mm away. The purpose of this research is to advance standard thermography techniques for damage detection by utilizing fiber optic sensor technologies.

We investigated a thermal nondestructive evaluation (NDE) technique based on thermography that uses optical fiber thermal sensors to detect damage within a laminated graphite epoxy composite specimen. Two sets of composite samples were used for testing, one set had fiber optic sensors embedded between the layers while the other relied on thermocouple sensors attached to the exterior. A simulated impact system was used to induce damage of varying degrees into the samples. The damage was confirmed either with X-ray or C-scan imaging. The test apparatus in addition to the test data obtained from both sets of samples are presented. The data confirms that the fiber optic thermal sensors can not only detect the presence of damage, but can measure the severity of damage as well. This is the first known attempt to use in situ fiber optic point sensors with thermography to detect damage.

This paper presents experimental results on thermomechanical behavior of Extrinsic Fabry-Perot Interferometric fiber optic strain sensors (EFPI-FOSS). The objective of this study was to determine the accuracy, strength characteristics, and durability properties of both bare (nonembedded) EFPI sensors, and embedded optical fiber sensors in either a neat resin or aerospace grade composite laminate. Experimental results suggest that the embedded EFPI sensors provide reliable strain measurements for values exceeding 10,000 μ∊ under static loading conditions. A major portion of this study focused on evaluating the long term tension–tension fatigue behavior of optical fiber sensors. Test data suggest the EFPI sensors provide reliable data up to 1 million cycles at fatigue strain levels below 3,000 μ∊. For fatigue strain levels above this value, failure of the fiber optic sensor was observed. While the sensor failed it did not influence the strength and fatigue life of the composite coupons. Considering the design strains used in aerospace components, these results provide evidence that the EFPI sensors will survive during the life of typical aerospace structures.

The magnetorefractive effect is a change in a sample’s reflectivity with applied magentic field. This is caused by the material’s index of refraction’s sensitivity to magnetic fields. However, measurements of the index of refraction as a function of applied magnetic field have not been previously published. This experimental study measures both the magnetorefractive effect and the index of refraction as a function of applied magnetic field and temperature in a 70 nm thick film of lanthanum strontium manganite La0.66Sr0.33MnO3. Index of refraction characterizations were performed with 633/nm light in magnetic fields ranging from −3 kOe to 3 kOe and near the Curie point, at temperatures from 278 K to 308 K.

This study reports on signal recovery of optical fiber Bragg gratings embedded in a carbon fiber composite overwrapped pressure vessel's (COPV) structure which have become chirped due to microcracks. COPVs are commonly used for the storage of high pressure liquids and gases. They utilize a thin metal liner to seal in contents, with a composite overwrap to strengthen the vessel with minimal additional mass. A COPV was instrumented with an array of surface mounted and embedded fiber Bragg gratings (FBGs) for structural health monitoring (SHM) via strain sensing of the material. FBGs have been studied as strain sensors for the last couple decades. Many of the embedded FBGs reflected a multi-peak, chirped response which was not able to be interpreted well by the current monitoring algorithm. Literature and this study found that the chirping correlated with microcracks. As loading increases, so does the number of chirped FBGs and microcracks. This study uses optical frequency domain reflectometry (OFDR) to demultiplex the array of FBGs, and then sub- divide individual FBGs. When a FBG is sub-divided using OFDR, the gratings' strain along its length is recovered. The sub-divided chirped FBGs have strain gradients along their length from microcracks. Applying this to all chirped gratings, nearly the entirety of the embedded sensors' readings can be recovered into a series of single peak responses, which show very large local strains throughout the structure. This study reports on this success in recovering embedded FBGs signal, and the strain gradient from microcracks.

The increased use of composite overwrapped pressure vessels (COPVs) in space and commercial applications, and the explosive nature of pressure vessel ruptures, make it crucial to develop techniques for early condition based damage detection. The need for a robust health monitoring system for COPVs is a high priority since the mechanisms of stress rupture are not fully understood. Embedded Fiber Bragg Grating (FBG) sensors have been proposed as a potential solution that may be utilized to anticipate and potentially avoid catastrophic failures. The small size and light weight of optical fibers enable manufactures to integrate FBGs directly into composite structures for the purpose of structural health monitoring. A challenging aspect of embedding FBGs within composite structures is the risk of potentially impinging the optical fiber while the structure is under load, thus distorting the optical information to be transferred. As the COPV is pressurized, an embedded optical sensor is compressed between the expansion of the inner bottle, and the outer overwrap layer of composite. In this study, FBGs are installed on the outer surface of a COPV bottle as well as embedded underneath a composite overwrap layer for comparison of strain measurements. Experimental data is collected from optical fibers containing multiple FBGs during incremental pressurization cycles, ranging from 0 to 10,000 psi. The graphical representations of high density strain maps provide a more efficient process of monitoring structural integrity. Preliminary results capture the complex distribution of strain, while furthering the understanding of the failure mechanisms of COPVs.

Preparations for a boundary-layer transition experiment to be conducted on a future  ight mission of the air-launched Pegasus® rocket are underway. The experiment requires a  ight-test article called a glove to be attached to the wing of the Mach-8 Ž rst-stage booster. A three-dimensional, nonlinear Ž nite element analysis has been performed and signiŽ cant small-scale laboratory testing has been accomplished to support the design and development of the  ight-test glove. Reliance on analyses and laboratory tests has been instrumental in achieving the structural stabilityand strength requirements for the glovedesign.Results obtained from the structural analysis and laboratorytesting show that all glove componentsare well within the allowable thermal stress and deformation requirements to satisfy experiment objectives.

The objective of this study was to determine the deflected wing shape and the out-of-plane loads of a large-scale carbon-composite wing of an ultralight aerial vehicle using Fiber Bragg Grating (FBG) technology. The composite wing, subjected to concentrated and distributed loads, was instrumented with an optical fiber on its top and bottom surfaces positioned over the main spar, resulting in approximately 780 strain sensors bonded to the wings. The in-plane strains from the FBG sensors were used to obtain the out-of-plane loads as well as the wing shape at various load levels using NASA-developed real-time load and displacement algorithms. The calculated out-of-plane displacements and loads were generally within 4% of the measured data.Copyright © 2013 by ASME

Patients with advanced peripheral vascular disease (PVD) and critical limb ischemia (CLI) require immediate revascularization to improve blood flow and prevent amputation. Vascular, and especially tibial, access is arguably a very important part of the procedure. Utilization of ultrasound (US) guidance to access the peripheral vessels will maximize success and decrease the risk of complications.This is a retrospective analysis of patients admitted to our institution between 2010 and 2011. Eighty-six patients with 191 lesions underwent revascularization for advanced PVD and CLI. US guidance was utilized to access the vascular bed in an antegrade or retrograde fashion in 100% of these patients. Data collected included success rate and time to access using US. Immediate in hospital and 30 day outcomes were also documented.The average age of patients was 69.8 years, with 69.7% male patients. All tibial access (33.7%) was obtained under US guidance. Obtaining vascular access using US was achieved in 95.3% of patients. At discharge, access site complications were limited to one patient (1.1%) with a pseudoaneurysm; no access complications related to the tibial vessels. At 30 days, there was one major amputation (1.1%) and one vascular access complication (1.1%).US guided access is a feasible and safe procedure that can aid in accessing vascular conduits in patients with CLI. Applying this technique across the board in CLI patients decreases the risk of immediate complications and facilitates accessing tibial arteries.

A modal approach is investigated for real-time deformation shape prediction of lightweight unmanned flying aerospace structures, for the purposes of Structural Health Monitoring (SHM) and condition assessment. The deformation prediction algorithm depends on the modal properties of the structure and uses high-resolution fiber-optic sensors to obtain strain data from a representative aerospace structure (e.g., flying wing) in order to predict the associated real-time deflection shape. The method is based on the use of fiber-optic sensors such as optical Fiber Bragg Gratings (FBGs) which are known for their accuracy and light weight. In this study, the modal method is examined through computational models involving Finite-Element Analysis (FEA). Furthermore, sensitivity analyses are performed to investigate the effects of several external factors such as sensor locations and noise pollution on the performance of the algorithm. This work analyzes the numerous complications and difficulties that might potentially arise from combining the state-of-the-art advancements in sensing technology, deformation shape prediction, and structural health monitoring, to achieve a robust way of monitoring ultra lightweight flying wings or next-generation commercial airplanes.

This study investigates the influence of lay-up and load direction on embedded optical fiber Bragg gratings (FBGs) used as strain sensors. FBGs have shown great promise for application to structural health monitoring with advantages of small size and cylindrical geometry readily allowing for embedment within fiber reinforced composites. Characterization of the embedded FBGs is necessary to develop a rugged and reliable strain sensor. This paper specifically explores the effects of loading direction on the FBG strain outputs. A well behaved baseline case is established with results for gratings loaded parallel to the optical fiber direction while embedded parallel to the adjacent structural fibers in a quasi-isotropic composite. Results and analysis are also presented for a case involving a composite fabricated with the optical and structural fibers parallel to each other but perpendicular to the loading direction. Extremely good results are obtained relating FBG strain measurements with that of surface mounted resistance strain gauges.Copyright © 2008 by ASME and US Government

This paper describes the sputter deposition and characterization of nickel titanium (NiTi) shape memory alloy thin film onto the surface of an optical fiber Bragg sensor. The NiTi coating uniformity, crystallinity and transformation temperatures are measured using scanning electron microsocopy, x-ray diffraction and differential scanning calorimetry respectively. The strain in the optical fiber is measured using centroid calculation of wavelength shifts. Results show distinct and abrupt changes in the optical fiber signal with the four related transformation temperatures represented by the austenite-martensite forward and reverse phase transformations. These tests demonstrate a coupling present between optical energy and thermal energy, i.e. a modified multiferroic material.

We investigated a thermal nondestructive evaluation (NDE) technique based on thermography that uses optical fiber thermal sensors to detect damage within a laminated graphite epoxy composite specimen. Composite samples manufactured for testing had fiber optic sensors embedded between layers and thermocouples attached to the exterior. A simulated impact system was used to induce damage of varying degrees into the samples and the damage was confirmed with C-span. The experimental procedures in addition to the test data obtained are presented. The results confirm that the fiber optic thermal sensors can not only detect the presence of damage, but can measure the severity of damage as well.

We investigated a thermal nondestructive evaluation (NDE) technique based on thermography that uses optical fiber sensors to detect damage within a laminated graphite epoxy composite specimen. Two sets of composite samples were used for testing, one set had fiber optic sensors imbedded between the layers and the other set did not. Thermocouples were attached to the front and back surfaces of all coupons for comparison. Damage was initiated in the samples at various levels with a simulated impact system and damage was confirmed with X-ray. Results suggest that the thermal approach is more sensitive to damage than the X-ray evaluation used. The test apparatus in addition to the results obtained from both sets of samples are presented.

Experimental results on mechanical behavior of Extrinsic Fabry-Perot Interferometric Fiber Optic Strain Sensors (EFPI-FOSS) are presented in this paper. The goal of this study was to determine the accuracy, strength characteristics, and durability properties of both bare (non-embedded) EFPI sensors, and embedded EFPI optical fiber sensors in either a neat resin or aerospace grade composite laminate. Experimental results suggest that the embedded EFPI sensors provide reliable strain measurements for values exceeding 10,000 (mu) (epsilon) under static loading conditions. A major portion of this study focused on evaluating the long term tension-tension fatigue behavior of optical fiber sensors. Test data suggest the EFPI sensors provide reliable data up to 1 million cycles at fatigue strain levels below 3,000 (mu) (epsilon) . For fatigue strain levels above this value, failure of the fiber optic sensor was observed. While the sensor failed it did not influence the strength and fatigue life of the composite coupons. Considering the design strains used in aerospace components, these results provide evidence that the EFPI sensors will survive during the life of typical aerospace structures.

A metallic 'glove' structure has been built and attached to the wing of the Pegasus(trademark) space booster. An experiment on the upper surface of the glove has been designed to help validate boundary-layer stability codes in a free-flight environment. Three-dimensional thermal analyses have been performed to ensure that the glove structure design would be within allowable temperature limits in the experiment test section of the upper skin of the glove. Temperature results obtained from the design-case analysis show a peak temperature at the leading edge of 490 F. For the upper surface of the glove, approximately 3 in. back from the leading edge, temperature calculations indicate transition occurs at approximately 45 sec into the flight profile. A worst-case heating analysis has also been performed to ensure that the glove structure would not have any detrimental effects on the primary objective of the Pegasus a launch. A peak temperature of 805 F has been calculated on the leading edge of the glove structure. The temperatures predicted from the design case are well within the temperature limits of the glove structure, and the worst-case heating analysis temperature results are acceptable for the mission objectives.

A new open-loop heat flux control technique has been developed to conduct transient thermal testing of thick, thermally-conductive aerospace structures. This technique uses calibration of the radiant heater system power level as a function of heat flux, predicted aerodynamic heat flux, and the properties of an instrumented test article. An iterative process was used to generate open-loop heater power profile prior to each transient thermal test. Differences between the measured and predicted surface temperatures were used to refine the heater power level command profiles through the iterative process. This iteration process has reduced the effects of environmental and test system design factors, which are normally compensated for by closed-loop temperature control, to acceptable levels. The final revised heater power profiles resulted in measured temperature time histories which deviated less than 25 degree(s)F from the predicted surface temperatures.