The overarching goal of this study was to develop a method to measure solid matrix stress, ex vivo, in the articular cartilage of three cadaveric human hip joints. The primary objectives were to establish the day to day repeatability of the method over three sequential days of testing before resecting the labrum on the fourth day to observe changes in joint behavior. Three to six fiber optic contact stress sensors were inserted within the middle zone of the acetabular cartilage to measure solid matrix stress in three hemipelvis hip specimens. A fiber optic hydrostatic fluid pressure sensor was used to simultaneously measure the synovial fluid pressure in the fossa while a representative physiological load was applied using a materials testing machine. Once inserted, the location of all sensors was quantified using a radio-stereometric analysis technique showing good repeatability of sensor location. The target radial positions of contact stress sensors were 0º, 25º, and 50º anterior of the AIIS and the observed positions were -1º ± 5º, 27º ± 3º and 56º ± 14º. Measurements of 0.26 ± 0.13 MPa and 0.440 ± 0.14 MPa for peak hydrostatic synovial fluid pressure show poor repeatability and no consistent change was observed after labral resection. Two contact stress sensors measured positive solid matrix stress values of 0.21 MPa and 0.69 MPa which agree with the findings of a similar experiment, however, poor day to day repeatability was observed. The difference between maximum and minimum stress values tended to be lower, and the nominal maximum solid matrix stress value higher, on the final day of testing after labral resection. No clear, consistent difference in the mean value of the solid matrix stress at the end of the test was found between tests with the intact labrum and after labral resection. Significant cross-sensitivity artifact is suspected in the solid matrix stress measurements significantly limiting the results. Several recommendations to improve upon these limitations in future work have been identified. Despite challenges during the experimental work and poor repeatability of measurements from the fiber optic sensors, incremental advances were made toward achieving the goal of developing a measurement system for cartilage solid matrix stress in the hip. / Graduate

Position and navigation of vehicle in two and three dimensions have been important as being advanced technology. Therefore, some system has been evaluated to get information of vehicle&rsquo / s position. Main problem in navigation is how to determine position and rotation in three dimensions. If position and rotation is determined, navigation will also be determined with respect to their initial point. There is a technology that vehicle velocity can be discovered, but a technology that rotation can be discovered is needed. Sensor which sense rotation is called gyroscope. If this instrument consists of optical and solid state material, it&rsquo / s defined by Fiber Optic Gyroscope (FOG). There are various studies in order to increase the sensitivity of fiber optic gyroscopes, which is an excellent vehicle for sensing rotation. One of them is interferometric fiber optic gyroscope with amplified optical feedback (FE_FOG). In this system, a feedback loop, which sent the output pulse through the input again, is used. The total output is the summation of each interference and it is in pulse state. The peak position of the output pulse is shifted when rotation occurs. Analyzing this shift, the rotation angle can be determined. In this study, fiber optic gyroscopes, their components and performance characteristics were reviewed. The simulation code was developed by VPIsystems and I used VPItransmissionMakerTM software in this work. The results getting from both rotation and nonrotation cases were analyzed to determine the rotation angle and sensitivity of the gyroscope.

Stemming from a 2011 incident inside of a Facebook data facility in which hyper-cooled air formed a literal (if somewhat transient) rain cloud in the stacks, It was raining in the data center examines ideas of non-places and supermodernity applied to contemporary network infrastructure. It was raining in the data center argues that the problem of the rain cloud is as much a problem of psychology as it is a problem of engineering. Although humidity-management is a predictable snag for any data center, the cloud was a surprise; a self-inflicted side-effect of a strategy of distance. The rain cloud was a result of the same rhetoric of ephemerality that makes it easy to imagine the inside of a data center to be both everywhere and nowhere. This conceit of internet data being placeless shares roots with Marc Augé’s idea of non-places (airports, highways, malls), which are predicated on the qualities of excess and movement. Without long-term inhabitants, these places fail to tether themselves to their locations, instead existing as a markers of everywhere. Such a premise allows the internet to exist as an other-space that is not conceptually beholden to the demands of energy and landscape. It also liberates the idea of ‘the network’ from a similar history of industry. However, the network is deeply rooted in place, as well as in industry and transit. Examining the prevalence of network overlap in American fiber-optic cabling, it becomes easy to trace routes of cables along major US freight train lines and the US interstate highway system. The historical origin of this network technology is in weaponization and defense, from highways as a nuclear-readiness response to ARPANET’s Pentagon-based funding. Such a linkage with the military continues today, with data centers likely to be situated near military installations— sharing similar needs electricity, network connectivity, fair climate, space, and invisibility. We see the repetition of militarized tropes across data structures. Fiber-optic network locations are kept secret; servers are housed in cold-war bunkers; data centers nest next to military black-sites. Similarly, Augé reminds us that non-places are a particular target of terrorism, populated as they are with cars, trains, drugs and planes that turn into weapons. When the network itself is at threat of weaponization, the effect is an ambient and ephemeral fear; a paranoia made of over-connection.

High-performance embedded systems communicating heterogeneous traffic with high bandwidth and strict timing requirements are in need of more efficient communication solutions. This thesis proposes two multi-wavelength passive optical networks able to meet these demands. The networks are based upon a single-hop star topology with an Arrayed Waveguide Grating (AWG) placed in the centre. The intended application areas for the two networks are short range embedded communication systems like System Area Networks (SANs) and router architectures with electronic queuing. The AWG’s attractive property of spatial wavelength reuse, as well as the combination of fixed-tuned and tuneable transceivers in the end nodes, enables simultaneous control and data traffic transmission. This, in turn, makes it possible to support heterogeneous traffic with both hard and soft real-time constraints. Additionally, two Medium Access Control (MAC) protocols, one for each network solution, are developed. Traffic scheduling is centrally controlled by a node, the protocol processor, residing together with the AWG in a hub. All nodes use Earliest Deadline First (EDF) scheduling and communicate with the protocol processor through physical control channels. A case study, including simulations, in the field of Radar Signal Processing (RSP) and simulations using periodic real-time traffic are conducted for the two application areas respectively, showing very good results. Further, a deterministic real-time analysis is conducted to provide throughput and delay guarantees for hard real-time traffic and an increase in guaranteed traffic is achieved through an analysis of existing traffic dependencies in a multichannel network. Simulation results incorporating the traffic dependency analysis indicate a considerable increase in the possible guaranteed throughput of hard real-time traffic.

Future parallel computer systems for embedded real-time applications,where each node in itself can be a parallel computer, are predicted to havevery high bandwidth demands on the interconnection network. Otherimportant properties are time-deterministic latency and guarantees to meetdeadlines. In this thesis, a fiber-optic passive optical star network with amedium access protocol for packet switched communication in distributedreal-time systems is proposed. By using WDM (Wavelength DivisionMultiplexing), multiple channels, each with a capacity of several Gb/s, areobtained. A number of protocols for WDM star networks have recently been proposed.However, the area of real-time protocols for these networks is quiteunexplored. The protocol proposed in this thesis is based on TDMA (TimeDivision Multiple Access) and uses a new distributed slot-allocationalgorithm with real-time properties. Services for both guarantee-seekingmessages and best-effort messages are supported for single destination,multicast, and broadcast transmission. Slot reserving can be used toincrease the time-deterministic bandwidth, while still having an efficientbandwidth utilization due to a simple slot release method. By connecting several clusters of the proposed WDM star network by abackbone star, thus forming a star-of-stars network, we get a modular andscalable high-bandwidth network. The deterministic properties of thenetwork are theoretically analyzed for both intra-cluster and inter-clustercommunication, and computer simulations of intra-cluster communicationare reported. Also, an overview of high-performance fiber-opticcommunication systems is presented.

Femtosecond (fs) laser micromachining has been a useful technique either to modify and remove materials or to change the properties of a material, and can be applied to transparent and absorptive substances. Recently high-power fs laser radiation has drawn intensive attention for the induction of refractive index change to fabricate micro-structures in dielectric materials. This thesis studies the optical properties of a novel fiber random grating fabricated by fs laser micromachining technique and extends its applications from optical sensing to random fiber lasers and optical random bit generations. The thesis mainly consists of three parts. In the first part, the physical mechanism behind the fs laser micromachining technique and the fabrication of the fiber random grating are introduced. By employing a wavelength-division spectral cross-correlation algorithm, a novel multi-parameter fiber-optic sensor based on the fiber random grating is proposed and demonstrated to realize simultaneous measurements of temperature, axial strain, and surrounding refractive index. In the second part, Brillouin random fiber laser (BRFL) and Erbium-doped fiber random laser (EDFRL) are introduced, respectively. Firstly, we propose a novel Brillouin random fiber laser with a narrow linewidth of ~860 Hz based on the bi-directionally pumped stimulated Brillouin scattering (SBS) in a 10-km-long optical fiber. A random fiber Fabry-Perot (FP) resonator is built up through the pump depletion effects of SBS at both ends of the fiber. The novel laser is successfully applied for linewidth characterization beyond 860 Hz of light source under test. Secondly, the random grating-based FP resonator is introduced to build up a novel BRFL with narrow-linewidth of ~45.8Hz and reduced lasing threshold. The intensity and frequency noises of the proposed random laser are effectively suppressed due to the reduced resonating modes and mode competition. Finally, the fiber random grating is used as random distributed feedback in an EDFRL to achieve both static (temperature, strain) and dynamic (ultrasound) parameter sensing. Multiple lasing lines with high signal-to-noise ratio (SNR) up to 40dB are achieved, which gives an access for a high-fidelity multiple-static-parameter sensing application. By monitoring the wavelength shifts of each peak, temperature and strain have been simultaneously measured with small errors. The fiber random grating in the EDFRL is also able to sense the ultrasound waves. By achieving single mode lasing with the EDFRL, ultrasound waves with frequencies from 20kHz to 0.8MHz could be detected with higher sensitivity and SNR improvement up to 20dB compared with conventional piezoelectric acoustic sensors. In the third part, we demonstrate that a semiconductor laser perturbed by the distributed feedback from a fiber random grating can emit light chaotically without the time delay signature (TDS). A theoretical model is developed by modifying the Lang-Kobayashi model to numerically explore the chaotic dynamics of the laser diode subjected to the random distributed feedback. It is predicted that the random distributed feedback is superior to the single reflection feedback in suppressing the TDS. In experiments, The TDS with the maximum suppression is achieved with a value of 0.0088, which is the smallest to date.

Distributed sensing is highly desirable in a wide range of civil, industrial and military applications. The current technologies for distributed sensing are mainly based on the detection of optical signals resulted from different elastic or non-elastic light-matter interactions including Rayleigh, Raman and Brillouin scattering. However, they can measure temperature or strain only to date. Therefore, there is a need for technologies that can further expand measurement parameters even to chemical and biological stimuli to fulfill different application needs. This dissertation presents a fully-distributed fiber-optic sensing technique based on a traveling long-period grating (T-LPG) in a single-mode fiber. The T-LPG is generated by pulsed acoustic waves that propagate along the fiber. When there are changes in the fiber surrounding medium or in the fiber surface coating, induced by various physical, chemical or biological stimuli, the optical transmission spectrum of the T-LPG may shift. Therefore, by measuring the T-LPG resonance wavelength at different locations along the fiber, distributed measurement can be realized for a number of parameters beyond temperature and strain. Based on this platform, fully-distributed temperature measurement in a 2.5m fiber was demonstrated. Then by coating the fiber with functional coatings, fully-distributed biological and chemical sensing was also demonstrated. In the biological sensing experiment, immunoglobulin G (IgG) was immobilized onto the fiber surface, and the experimental results show that only specific antigen-antibody binding can introduce a measurable shift in the transmission optical spectrum of the T-LPG when it passes through the pretreated fiber segment. In the hydrogen sensing experiment, the fiber was coated with a platinum (Pt) catalyst layer, which is heated by the thermal energy released from Pt-assisted combustion of H2 and O2, and the resulted temperature change gives rise to a measurable T-LPG wavelength shift when the T-LPG passes through. Hydrogen concentration from 1% to 3.8% was detected in the experiment. This technique may also permit measurement of other quantities by changing the functional coating on the fiber; therefore it is expected to be capable of other fully-distributed sensing applications. / Ph. D.

No description available.

<p>The rapid development of fiber optic communication systems requires higher transmission data rate and longer reach. This thesis deals with the limiting factors in design of long-haul fiber optic communication systems and the techniques used to suppress their resulting impairments. These impairments include fiber chromatic dispersion, the Ker nonlinearity and nonlinear phase noise due to amplified spontaneous emission.</p> <p>In the first part of this thesis, we investigate the effect of amplified spontaneous noise in quasi-linear systems. In quasi-linear systems, inline optical amplifiers change the amplitude of the optical field envelope randomly and fiber nonlinear effects such as self phase modulation (SPM) convert the amplitude fluctuations to phase fluctuations which is known as nonlinear phase noise. For M-ary phase shift keying (PSK) signals, symbol error probability is determined solely by the probability density function (PDF) of the phase. Under the Gaussian PDF assumption, the phase variance can be related to the symbol error probability for PSK signals. We implemented the simulation based on analytical phase noise variance and Monte-Carlo simulation, and it is found that the analytical approximation is in good agreement with numerical simulations. We have developed analytical expressions for the linear and nonlinear phase noise variance due to SPM using second-order perturbation theory. It is found that as the transmission reach and/or lunch power increase, the variance of the phase noise calculated using first order perturbation theory becomes inaccurate. However, the variance calculated using second order perturbation theory is in good agreement with numerical simulations. We have also showed that the analytical formula given in this chapter for the variance of nonlinear phase noise can be used as a design tool to investigate the optimum system design parameters such as average power and dispersion maps for coherent fiber optic systems based on phase shift keying due to the fact that the numerical simulation of nonlinear Schrodinger (NLS) equation is time consuming, however, the analytical method based on solving NLS equation using perturbation approximation is quite efficient and therefore the analytical variance can be obtained more easily without requiring extensive computational efforts, and also with fairly good accuracy.</p> <p>In the second part of this thesis, an improved optical signal processing using highly nonlinear fibers is studied. This technique, optical backward propagation (OBP), can compensate for the fiber dispersion and nonlinearity using optical nonlinearity compensators (NLC) and dispersion compensating fibers (DCF), respectively. In contrast, digital backward propagation (DBP) uses the high-speed digital signal processing (DSP) unit to compensate for the fiber nonlinearity and dispersion digital domain. NLC imparts a phase shift that is equal in magnitude to the nonlinear phase shift due to Fiber propagation, but opposite in sign. In principle, BP schemes could undo the deterministic (bit-pattern dependent) nonlinear impairments, but it can not compensate for the stochastic nonlinear impairments such as nonlinear phase noise. We also introduced a novel inline optical nonlinearity compensation (IONC) technique. Our Numerical simulations show that the transmission performance can be greatly improved using OBP and IONC. Using IONC, the transmission reach becomes almost twice of DBP. The advantage of OBP and IONC over DBP are as follows: OBP/IONC can compensate the nonlinear impairments for all the channels of a wavelength division multiplexed system (WDM) in real time while it would be very challenging to implement DBP for such systems due to its computational cost and bandwidth requirement. OBP and IONC can be used for direct detection systems as well as for coherent detection while they provide the compensation of dispersion and nonlinearity in real time, but DBP works only for coherent detection and currently limited to off-line signal processing.</p> / Master of Applied Science (MASc)

Fiber optic temperature and vibration sensors were designed and built to take readings in the harsh environment of a steel mill. The sensors are insensitive to electromagnetic noise; making them well suited for the use in such an environment. The temperature sensor uses an optical filter technique. A piece of intrinsic silicon is inserted between two optical fibers and 1064nm wavelength light is transmitted through the silicon. As the temperature increases, the silicon becomes more highly absorbing. The vibration sensor uses an optomechanical technique. Light is transmitted across a short air gap between two optical fibers. One of the fibers acts as cantilever while the other is fixed. As the cantilever vibrates, the transmitted power fluctuates, which enables the detection of the frequency and amplitude of the vibration. Sensors were initially tested under laboratory conditions, and subsequently field tested at ArcelorMittal Dofasco. The temperature sensor has a sensitivity of 0.4°C over the temperature range from 22°C to 120°C. The vibration sensor has a sensitivity of 2.87mV /g peak over a frequency range from 0 to 1250 Hz. / Thesis / Master of Applied Science (MASc)