1,191 research outputs found
Investigation of LEO environment exposure monitoring potential using embedded FBG sensors
No full textComposite materials provide many advantages over conventional materials including metals, especially for space applications. However, composites have failure modes that are complex and difficult to identify, and various cracks and delamination are predominantly difficult to detect visually. In this regard, an effective method of monitoring the integrity of composite materials and structures exposed to hazardous space environments is necessary to ensure the long-term reliability of composite materials in aerospace applications. FBG sensors are advantageous for space applications due to their immunity to various environments. In this study, FBG sensors were used to investigate LEO environment exposure monitoring of CFRP
Investigation of Multi-layer Embedded FBG Sensor Response under Simulated LEO Environment Exposure
No full textEffects of the Bonding Length on the Reflected Spectra and Strain Measurement of the Surface Bonded Fiber Bragg Grating Sensor
No full textLow velocity impact monitoring of composite wing structure under simulated wing loading condition using fiber Bragg grating sensors
No full textA low velocity impact onto a composite structure can result in the occurrence of barely visible impact damage (BVID), which is difficult to detect. Therefore, the low velocity impact monitoring of composite structures is highly desirable for impact detection and localization. In this paper, low velocity impacts on a composite wing under a simulated wing loading condition were monitored using six multiplexed fiber Bragg grating (FBG) sensors and localized using error outlier based impact localization algorithm. The impact response signals from the FBG sensors were sampled at a rate of 100 kHz using high-speed interrogator. The impacts were localized with an average error of 18.4 mm
Signal characteristics of the surface bonded fiber Bragg grating sensors by bonding length under different load types
No full textThe surface-bonding method of the fiber Bragg grating(FBG) sensor is easier to handle than embedding method. However surface bonded FBG sensors have the limitation of the signal characteristics being affected by the bonding layer. In this study, the effects of the bonding length on the surface installed FBG sensor signal characteristics under various load types were empirically investigated. To evaluate the stability of the signal characteristics of the FBG sensors, the strain transfer rate and the multiple peaks ratio of the reflected spectrum were calculated and compared. From the experimental results, the strain transfer ratio and multiple peaks ratio varied because of the different strain gradients formed depending on the applied load type. Therefore, it was found that the effective bonding length for respective load types need to be determined to get a stable signal from the surface bonded FBG sensors
Effect of tubing material on conventional and thin FBG sensor for embedded environment impact monitoring of CFRP composites
No full textApplications of composite materials in aerospace structures is increasing due to the outstanding properties, however, monitoring such composite structures exposed to harsh environments is still a posing issue. Low Earth orbit space structures are exposed to property degradation and damage from high-degree vacuum, ultraviolet radiation, thermal cycling, and atomic oxygen attack which are detrimental to composite materials. In this study, FBG sensors for embedding in CFRP composite plates in different thickness locations to provide health and damage monitoring of the material exposed to such environments regarding the overall health of the material with a focus on the exposed surface are explored in comparison to conventional FBG sensors
One Place After Another : Site-Specific Art and Locational Identity
No full textKwon traces the development of site-specific art from the 1960s to the 1990s, examining site-specificity as a locus of the dynamic relationship between place and identity in late capitalism. The author distinguishes the more recent work from the earlier by highlighting how it points to the exhaustion of the rhetoric of political progressivism inherent in the practice. Characterising community as an inoperative spectre, Kwon calls for new models of belonging. Index. Circa 300 bibl. ref
Suppressing Anion Repulsion for Enhancing Li-Mediated Nitrogen Reduction
No full textElectrochemical lithium-mediated nitrogen reduction (Li-NRR) presents a sustainable alternative to Haber-Bosch for ammonia synthesis. Efficiency and stability are critically governed by the solid electrolyte interphase (SEI), which regulates reactant transport and suppresses side reactions. While anion-derived SEI formed under anion-rich solvation is beneficial, conventional electric double layer (EDL) repel anion at the cathode, limiting favorable SEI formation. Therefore, this study introduces cationic ionomer additives that form a positively charged ionic interfacial layer, mitigating anion repulsion and reducing interfacial solvent accumulation. An imidazolium (C3H4N2)-functionalized cation ionomer enables the formation of a tailored EDL, achieving a Faradaic efficiency and ammonia yield of 92 +/- 3% and 58 +/- 4 nmol s-1 cm-2, markedly surpassing the conventional EDL (63 +/- 7%, 28 +/- 9 nmol s-1 cm-2). A significant decrease in anion repulsion was confirmed via computational and in situ spectroscopic analyses. The demonstrated applicability across various lithium salts clearly reveals the overall effectiveness of this cationic ionomer-based EDL engineering in Li-NRR.
Move over Marcus Welby, M.D. and Make Way for Managed Care: The Implications of Capitation, Gag Clauses, and Economic Credentialing
No full textThe author examines the transformative impact of managed care on the medical profession and patient-provider relationships. The article highlights the implications of capitation, gag clauses, and economic credentialing in shaping healthcare delivery and physician autonomy. Kwon argues that these practices can undermine the quality of care and patient trust, as financial incentives often prioritize cost savings over patient welfare. Through a critical analysis, the author calls for reforms to address the ethical challenges posed by managed care systems. Ultimately, the piece advocates for a healthcare model that balances economic efficiency with the fundamental principles of patient-centered care
Unilateral partial nephrectomy with warm ischemia results in acute Hypoxia inducible factor 1-alpha (HIF-1α) and toll-like receptor 4 (TLR4) overexpression in a porcine model
No full textPurpose: Ischemia/reperfusion (I/R) during partial nephrectomy (PN) contributes to acute kidney injury (AKI), which is inaccurately assessed using existent clinical markers of renal function. We evaluated I/R-related changes in expression in hypoxia inducible factor 1α (HIF-1α) and toll-like receptor 4 (TLR4), within kidney tissue and peripheral blood leukocytes (PBL) in a porcine model of PN.
Materials and Methods: Three adult pigs each underwent unilateral renal hilar cross clamping for 180 min followed by a 15 min reperfusion. The contralateral kidney served as control. Biopsies of clamped kidneys were obtained at baseline (time 0), every 60 min during the hypoxic phase, and post-reperfusion. Control kidneys were biopsied once at 180 min. Peripheral blood was sampled at time 0, every 30 min during the hypoxic phase, and post-reperfusion. HIF-1α and TLR4 expression in kidney tissue and PBL were analyzed by Western blotting. I/R-related histological changes were assessed.
Results: Expression of HIF-1α in clamped kidneys and PBL was below detection level at baseline, rising to detectable levels after 60 min of hypoxia, and continuing to rise throughout the hypoxic and reperfusion phases. Expression of TLR-4 in clamped kidneys followed a similar trend with initial detection after 30–60 min of hypoxia. Control kidneys exhibited no change in HIF-1α or TLR-4 expression. I/R-related histologic changes were minimal, primarily mild tubular dilatation.
Conclusions: In a porcine model of PN, HIF-1α and TLR4 exhibited robust, I/R-related increases in expression in kidney tissue and PBL. Further studies investigating these molecules as potential markers of AKI are warranted.Peer reviewe
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