Effect of blood's velocity on blood resistivity

Blood resistivity is an important quantity whose value influences the results of various methods used in the study of heart and circulation. In this paper, the relationship between blood resistivity and velocity of blood flow was evaluated and analyzed based upon a probe using six-ring electrodes and a circulatory model. The experimental results indicated that the change in blood resistivity was only ±1.1% when the velocity of blood flow changed from 2.83 to 40 cm/s and it rose to 23% when the velocity was lower than 2.83 cm/s

Practical issues in using novel sensors in SHM of civil infrastructure: problems and solutions in implementation of GPS and fibre optic sensors

Author's manuscript of paper presented at the Fourth International Workshop on Structural Health Monitoring, September 15-17, 2003. Deposited with permission of the publisher.Published version of full conference proceedings available for purchase from the publisher via http://www.destechpub.com/index.php?fuseAction=catalogs.viewItem&catalogID=1&catalogLevelID=&catalogItemID=136Proceedings published as: Structural Health Monitoring 2003; From Diagnosis & Prognostics to Structural Health Management; Proceedings of the Fourth International Workshop on Structural Health Monitoring, September 15-17, 2003; Editor: Fu-Kuo Chang, Department of Aeronautics and Astronautics, Stanford University; ISBN13: 978-1-932078-20-6, 1-932078-20-7, September 2003.This article appeared in Structural Health Monitoring 2003—Proceedings of the 4th International Conference Workshop on Structural Health Monitoring, 2003. Lancaster, PA: DEStech Publications, Inc.Two contemporary research programs have explored the use of newer type of sensors believed, and advertised, to have potential in future implementation of SHM system for civil structures. Fibre optic sensors have the possibility to record a range of physical parameters simultaneously and at high speed through multiplexing capabilities of the fibre Bragg grating (FBG); GPS has the advantage to measure absolute displacement of slowly moving flexible structures without need for optical line of sight. FBG sensors have been tested in laboratory situations and have finally been implemented for strain measurements in an expressway viaduct construction program. Meanwhile, a twin-rover GPS system mounted on top of one of Singapore’s tallest buildings has recently provided real-time static and dynamic response data as part of an existing monitoring system designed to study structural performance during wind and earthquake loading. Some of the first results of these two programs will be presented. Both implementations have been problematic in different ways and the paper will identify some of the difficulties and the solutions adopted. The practical limitations and optimal applications can thus be identified

Carbon-nanotube-deposited long period fiber grating for continuous refractive index sensor applications

We present a carbon-nanotube-deposited long period fiber grating for refractive index sensing applications in liquid. Carbon nanotubes are deposited around the surface of a long period fiber grating to form the refractive index sensing element. The sensing mechanism relies mainly on the high refractive index properties of the carbon-nanotube thin film, which enhances the cladding mode of the long period fiber grating in order to have a significant interaction between the propagating light and the target medium. A sensitivity of 31 dB/RIU and 47 dB/RIU are obtained for the refractive index ranges of 1.33-1.38 and 1.38-1.42, respectively, which have not been demonstrated with normal long period fiber gratings as the sensing element. As the sensing mechanism is based on the change of the transmitted optical power, our proposed scheme can intrinsically solve the limitations of the free spectral range commonly seen in other reported schemes, and continuous and repeatable measurements can be obtained while only acquiring errors mainly from the power fluctuations from the light source. The fiber grating also does not require any further mechanical modification like etching or tapering, which allows the sensing element to have the advantage of mechanical strength for practical applications. The experimental results are consistent with the modeling of the sensing mechanism. © 2014 Elsevier B.V. All rights reserved

Novel Tunable Fiber Optic Edge Filter Based on Modulating Chirp Rate of pi-Phase-Shifted Fiber Bragg Grating

We propose and experimentally demonstrate a novel tunable fiber optic edge filter based on modulating the chirp rate of a pi-phase-shifted fiber Bragg grating (FBG) operated in reflection mode. The phase shift induced notch in the reflection spectrum is utilized as the edge filter. The dependence of the pi-phase-shifted FBG's spectral response on the chirp rate has been numerically studied in detail and experimentally confirmed for the first time. The linear wavelength range of this edge filter can be tuned by changing the chirp rate of FBG. A fiber optic edge filter is further obtained experimentally and tested as a wavelength interrogator, which is in a good agreement with numerical results. The proposed edge filter has advantages of simple-structure, cost-effectiveness, high sensitivity, and flexible tunable, thus opening up some applications, especially as wavelength interrogator in small wavelength range

In-depth investigation of the molecular pathogenesis of bladder cancer in a unique 26-year old patient with extensive multifocal disease: A case report

Background. The molecular characteristics and the clinical disease course of bladder cancer (BC) in young patients remain largely unresolved. All patients are monitored according to an intensive surveillance protocol and we aim to gain more insight into the molecular pathways of bladder tumors in young patients that could ultimately contribute to patient stratification, improve patient quality of life and reduce associated costs. We also determined whether a biomarker-based surveillance could be feasible. Case Presentation. We report a unique case of a 26-year-old Caucasian male with recurrent non-muscle invasive bladder tumors occurring at a high frequency and analyzed multiple tumors (maximal pTaG2) and urine samples of this patient. Analysis included FGFR3 mutation detection, FGFR3 and TP53 immunohistochemistry, mircosatellite analysis of markers on chromosomes 8, 9, 10, 11 and 17 and a genome wide single nucleotide polymorphism-array (SNP). All analyzed tumors contained a mutation in FGFR3 and were associated with FGFR3 overexpression. None of the tumors showed overexpression of TP53. We found a deletion on chromosome 9 in the primary tumor and this was confirmed by the SNP-array that showed regions of loss on chromosome 9. Detection of all recurrences was possible by urinary FGFR3 mutation analysis. Conclusions. Our findings would suggest that the BC disease course is determined by not only a patient's age, but also by the molecular characteristics of a tumor. This young patient contained typical genetic changes found in tumors of older patients and implies a clinical disease course comparable to older patients. We demonstrate that FGFR3 mutation analysis on voided urine is a simple non-invasive method and could serve as a feasible follow-up approach for this young patient presenting with an FGFR3 mutant tumor

In-situ measurement and numerical simulation of resin pressure during Glass/Epoxy prepreg composite manufacturing

Resin pressure distribution of a curing Glass/Epoxy prepreg lay-up is the key parameter that controls the strength, stiffness and void nucleation of the cured composite part. It is vital to monitor and control the resin movement of curing laminate to optimize its quality in any manufacturing process. In this paper, design of a Fiber Bragg grating (FBG) based device, capable of measuring in-situ resin pressure of a curing lay-up is presented. This device uses the principle of differential pressure in liquids. The device was calibrated using a water column, and a pressure sensitivity of 1.636 × 10−2 MPa−1 was yielded. FBG responds linearly with the rise of hydrostatic pressure in the water column. An excellent agreement was found between experimental and theoretical results. This device was used to monitor the resin pressure in a curing prepreg composite lay-up. The measured liquid resin pressures were also compared to the resin pressure obtained from a coupled multi-physics numerical simulation. The presented sensor is useful for in-situ pressure measurements, especially for high temperature and low or zero bleed curing of composites, for example, out of autoclave curing

Damage initiation and growth in laminates with ply drop-offs under quasi-static and fatigue loading

The thickness of a laminated composite structure can be varied by reducing the number of plies through the thickness of the composite material (i.e. using ply drop-offs), where one or more plies are terminated prematurely at some position within the composite, or at the surface. One of the disadvantages of using ply drop-offs is the likelihood of stress concentrations at the terminations of the dropped plies, as these stress concentrations frequently lead to the premature development of damage. In this work, composite coupons with a double ply drop-off have been fabricated using out-of-autoclave CFRP. Coupons cut from the panels have been subjected to quasi-static and fatigue loading and the development of damage has been monitored using microscopy, and in some coupons, by using a chirped fibre Bragg grating (CFBG) sensor. The first damage appeared as resin cracks within the resin pocket associated with the ply drop-off and this damage developed subsequently into delaminations. Under quasi-static loading, the delaminations grew stably within the ply drop-off region with increasing load; under fatigue loading, the delaminations grew with a constant growth rate. The paper will present observations on the initiation and growth of the damage

Damage initiation and growth in laminates with ply drop-offs under quasi-static and fatigue loading

The thickness of a laminated composite structure can be varied by reducing the number of plies through the thickness of the composite material (i.e. using ply drop-offs), where one or more plies are terminated prematurely at some position within the composite, or at the surface. One of the disadvantages of using ply drop-offs is the likelihood of stress concentrations at the terminations of the dropped plies, as these stress concentrations frequently lead to the premature development of damage. In this work, composite coupons with a double ply drop-off have been fabricated using out-of-autoclave CFRP. Coupons cut from the panels have been subjected to quasi-static and fatigue loading and the development of damage has been monitored using microscopy, and in some coupons, by using a chirped fibre Bragg grating (CFBG) sensor. The first damage appeared as resin cracks within the resin pocket associated with the ply drop-off and this damage developed subsequently into delaminations. Under quasi-static loading, the delaminations grew stably within the ply drop-off region with increasing load; under fatigue loading, the delaminations grew with a constant growth rate. The paper will present observations on the initiation and growth of the damage

Effect of disbond propagation on the reflected spectra of CFBG sensors embedded within the bondline of composite bonded joints

Chirped fiber Bragg grating (CFBG) sensors were embedded within the adhesive bondline of single-lap CFRP-GFRP bonded composite joints. The effect of disbond propagation (as a consequence of fatigue loading) on the reflected spectra from the CFBG sensor has been studied. As the disbond propagates, thermal strains generated during the bonding of the joint at elevated temperature are released and, as a consequence, a peak in the reflected spectra of the CFBG sensor can be seen. Using a transparent GFRP adherend, it has been possible to demonstrate that there is reasonable agreement between the position of the peak in the reflected spectrum and the disbond front position in the bonded joint