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Background: Blood pressure (BP) is an essential indicator for human health and is known to be greatly influenced by lifestyle factors, like activity and sleep factors. However, the degree of impact of each lifestyle factor on BP is unknown and may vary between individuals. Our goal is to investigate the relationships between BP and lifestyle factors and provide personalized and precise recommendations to improve BP, as opposed to the current practice of general lifestyle recommendations. Method: Our proposed system consists of automated data collection using home BP monitors and wearable activity trackers and feature engineering techniques to address time-series data and enhance interpretability. We propose Random Forest with Shapley-Value-based Feature Selection to offer personalized BP modeling and top lifestyle factor identification, and subsequent generation of precise recommendations based on the top factors. Result: In collaboration with UC San Diego Health and Altman Clinical and Translational Research Institute, we performed a clinical study, applying our system to 25 patients with elevated BP or stage I hypertension for three consecutive months. Our study results validate our system’s ability to provide accurate personalized BP models and identify the top features which can vary greatly between individuals. We also validate the effectiveness of personalized recommendations in a randomized controlled experiment. After receiving recommendations, the subjects in the experimental group decreased their BPs by 3.8 and 2.3 for systolic and diastolic BP, compared to the decrease of 0.3 and 0.9 for the subjects without recommendations. Conclusion: The study demonstrates the potential of using wearables and machine learning to develop personalized models and precise lifestyle recommendations to improve BP.

Circular-symmetric optical fibres are ideal for studying nonlinear optical processes involving optical vortices [1] . Chiral photonic crystal fibres (PCFs), fabricated either by post-processing techniques or by spinning the preform during fibre drawing, have been shown to support circularly polarized helical Bloch modes (HBMs), which are superpositions of multiple vortices with topological charges l ( m ) = l (0) + mN , where N is the number of azimuthal periods and m the order of the m -th azimuthal Bloch harmonic [2] . Here we report on the importance of the preservation of topological charge in polarisation modulational instability (PMI) between circularly polarised modes in a circularly birefringent chiral PCF with a 3-fold rotationally symmetric core.

Knowledge of the phase and amplitude of an optical field is of critical importance in many applications, for example in measuring the carrier envelope phase of an ultrashort pulse. While the intensity spectrum can easily be obtained using a spectrometer, there is no direct method for measuring the phase. Retrieving phase information requires use of an interferometer to compare the signal phase against the phase of a known reference source. To resolve ambiguity in the sign of the phase, the field quadrature can be measured at the output of a polarising beam splitter [1] . Interferometry requires, however, that the reference source is stable and has a spectrum at least as broad as the one under study, which can in some cases be multi-octave in extent. Here we report an experiment in which the reference is provided by a supercontinuum generated in a twisted all-normal dispersion (t-ANDi) fibre.

Stimulated Brillouin scattering (SBS) in optical fibres, in which guided light is parametrically reflected by coherent acoustic phonons, provides a powerful and flexible mechanism for controlling light, and has recently been demonstrated with orbital angular momentum (OAM) modes in a special annular-core fibre [1] . Helically twisted photonic crystal fibre (PCF) robustly supports circularly-polarised helical Bloch modes (HBMs) and displays OAM birefringence, i.e., modes with equal and opposite OAM orders have different propagation constants [2] . Here we report for the first time SBS of circularly-polarised HBMs in a chiral 4-core PCF with 3-fold symmetry.

Wildfire from powerlines has cost hundreds of lives in North America and Australia. Research shows earth-fault current of half an amp can start fires. Measures to limit earth fault current to this level have been developed for three and two-wire polyphase networks, but these do not address fire risk from Single-Wire-Earth-Return (SWER) networks where load current returns via the earth. In this paper, a patented Early Fault Detection (EFD) system for SWER networks based on Internet-of-Things (IoT) and smart sensing is presented, together with field trial results obtained from rural networks in Victoria, Australia. Distributed EFD sensors on power poles measured high-frequency signals on the overhead conductor from partial discharge and other sources. Pre-processed data was uploaded to a secure cloud server for post-processing data matching and analysis. The trial validated the system sensitivity and ten-metre accuracy of signal source location. Three high fire-risk problems were located and remedied before the risk was realized.

In this work, we present peak-cognizant quantification of environmental weathering of crude oil from the from the Deepwater Horizon oil spill. The key idea is to autonomously extract peak information from raw gas chromatography-mass spectrometry (GC-MS) signals from crude oil samples, and represent the relative weathering of different peaks in a graph-based quantitative computational framework. We also present results from pre-processing the raw signals with baseline correction and signal normalization. Retention time alignment is performed by first aligning the source oil by determining the retention time drift between prominent peaks within the signals and applying the calculated drift to the weathered oil samples. Peak finding, validation, and grouping of the five weathered oil samples to a source oil sample allows compound associations to be discovered. We present preliminary results as graphical visualizations allowing for rapid and precise interpretation of weathering compounds within polycyclic aromatic hydrocarbons (PAH). Results presented were generated with oil samples showing different degrees of weathering collected from the Deepwater Horizon spill.

Due to the large-scale integration of renewable energy sources and high-voltage direct current (HVDC) links, the power grid is transforming into a hybrid AC/DC power grid. The critical clearing time (CCT) is used to evaluate the proximity of a power network to the instability point, hence can be used as a stability indicator for hybrid AC/DC power grids. Various factors influence the CCT of a hybrid AC/DC power network, especially voltage source converters (VSCs) significantly affect the CCT. This paper investigates the factors that influence the CCT of a hybrid AC/DC power grid with a VSC-HVDC link. The conventional CCT calculation procedure is exemplified with an AC power network. Subsequently, the CCT analysis procedure is carried out for a single-machine test system with a VSC-HVDC link. Influence of both controller parameters and power network parameters are investigated to assess their impact on CCT. According to the theoretical analysis and simulation results, the fault resistance, the DC bus capacitor, current controller limit and DC transmission line parameters have a significant influence on the CCT of a hybrid AC/DC power network. By selecting optimal values for the current limit of VSCs, the CCT could be improved in a hybrid AC/DC power network since others are network dependent parameters.

Deep learning has now become the de facto approach to the recognition of anomalies in medical imaging. Their 'black box' way of classifying medical images into anomaly labels poses problems for their acceptance, particularly with clinicians. Current explainable AI methods offer justifications through visualizations such as heat maps but cannot guarantee that the network is focusing on the relevant image region fully containing the anomaly. In this paper, we develop an approach to explainable AI in which the anomaly is assured to be overlapping the expected location when present. This is made possible by automatically extracting location-specific labels from textual reports and learning the association of expected locations to labels using a hybrid combination of Bi-Directional Long Short-Term Memory Recurrent Neural Networks (Bi-LSTM) and DenseNet-121. Use of this expected location to bias the subsequent attention-guided inference network based on ResNet101 results in the isolation of the anomaly at the expected location when present. The method is evaluated on a large chest X-ray dataset., Comment: 5 pages, Paper presented as a poster at the International Symposium on Biomedical Imaging, 2020, Paper Number 655

Recently, a new algorithm named dynamic group optimization (DGO) has been proposed, which is developed to mimic the behaviors of animal and human group socializing. However, one of the major drawbacks of the DGO is the premature convergence. Therefore, in order to deal with this challenge, we introduce chaos theory into the DGO algorithm and come up with a new chaotic dynamic group optimization algorithm (CDGO) that can accelerate the convergence of DGO. Various chaotic maps are used to adjust the update of solutions in CDGO. Extensive experiments have been carried out, and the results have shown that CDGO can be a very promising tool for solving optimization algorithms. We also demonstrated good results based on real world data, where, in particular, solving multimedia data clustering problems.

Providing uninterrupted, reliable and high-quality power supply to consumers have been very challenging for power utilities around the world. The utilities spend a considerable amount for the maintenance, inspection, testing and monitoring of power infrastructure to achieve the above. The overhead power lines are the main power carriers for the delivery of electricity to the consumers. These overhead power lines are prone to risk of fires and faults caused by vegetation encroachment and touches on the power corridor, resulting in damage to the conductors, power blackouts and catastrophic events such as wildfires or bushfires. Therefore, utilities have to regularly inspect and monitor powerlines for the prevention of damage. Utilities have been adopting foot patrol, aerial inspections and more recently LIDAR technology to inspect the overhead power lines on regular basis. However, these approaches only give "point of time" information and are time consuming and costly. This paper presents a novel technique which uses directional antennas mounted on poles carrying overhead conductor to detect the partial discharge (PD) signals generated by incipient faults in an experimental set up and also field testing. These PD signals are processed by FPGA signal processing unit for peak detection and filtering and digest of the signals is delivered to a secured cloud server for post-data processing such as trend analysis, pattern recognition and localisation. This paper demonstrates the effectiveness of this Early Fault Detection (EFD) technique to accurately locate vegetation encroachment and partial discharge originated from broken insulators, defective gas switches and transformers. This technology has been successfully employed at various locations on distribution feeders in Australia and the results are very encouraging.

The application of functionally graded materials with spatial distribution of dielectric properties (d-FGM) can be an effective solution in reducing the electric field stress within an insulation system. In this work, the d-FGM material was synthesized using lamination method and half-curing process. The lamination is made up silicone rubber as the host matrix and nano-sized ZnO and a mixture of nano-sized ZnO and BaTiO 3 with optimized permittivity and conductivity properties. Both simulation and experimental results shows an improvement in the electric field enhancement by using d-FGM.

Over the past decade, a massive research interest has been devoted to zinc oxide (ZnO) and barium titanate (BaTiO 3 )-based nanocomposites. ZnO is a piezoelectric semiconductor particle, which is often used to improve the conductivity of a host matrix whereas BaTiO 3 , that is generally regarded as ferroelectric particles, will increase the dielectric performance of a matrix. In this work, we studied samples of nanocomposites which are fabricated using ZnO, BaTiO 3 nanoparticles as well as the mixture of both particles in a silicone rubber matrix. The AC electrical performance as well as thermomechanical performance of the nanocomposites are studied, and results are presented.

Many different techniques have been used to model the electromagnetic response of photonic crystal fibres (PCFs) and waveguide arrays. Here we introduce a new vectorial approach based on helical Bloch waves (hBWs) that appear in structures (such as many PCFs) that are N-fold rotationally symmetric (symmetry group C n ), i.e., they repeat perfectly in N sectors over 2π, when viewed in a cylindrical coordinate frame [1]. Helical Bloch waves can also carry optical angular momentum: a complex Bloch wave field propagates azimuthally around the axis of the structure, forming helical Bloch modes (hBMs) when a certain azimuthal resonance condition is satisfied.

Light beams carrying orbital angular momentum (OAM) are of fundamental interest in many fields of research [1]. Recently it has been reported that helical Bloch modes (HBMs) carrying multiple values of OAM are guided in chirally twisted photonic crystal fibre (PCF), even when there is no core [2]. HBMs are not supported by conventional waveguides and would be very difficult to realise using multi-beam interference. Here we report the first complete experimental characterisation of the phase and amplitude of the complex HBM fields in twisted coreless PCF. We compare the measurements with finite element simulations, based on precise scanning electron micrographs of the fibre structure, obtaining excellent agreement. We then expand the numerically calculated HBM fields as a series of Bessel beams, allowing us to calculate the strengths and azimuthal orders of the HBM harmonics with a fidelity greater than 95%.

Supercontinuum (SC) generation in solid-core photonic crystal fibres (PCFs) is well established and has diverse applications in science and technology [1,2]. In a conventional SC, the polarization state is not maintained over the whole spectrum due to cross-phase modulation and may in addition vary with power. Recently, it has been reported that continuously twisted PCFs exhibit circular birefringence [3,4]. Here we report the first experimental demonstration of a twisted PCF that robustly maintains circular polarization state across the whole spectrum, independent of power.

The power network architecture is rapidly evolving with the addition of high-voltage direct current (HVDC) transmission links and dc distribution networks. The voltage-source converter (VSC) based HVDC (i.e. VSC-HVDC) shows advantage in rotor angle stability control due to its ability to adjust active power and reactive power independently. This paper provides a rotor angle comparison between a single-machine-infinite-bus (SMIB) system with two paralleled AC transmission lines and a SMIB with one AC transmission line and one VSC- HVDC link. A detailed analysis is conducted based on the swing equation and the damping power of the generator is critically analysed in the study. A solid three-phase fault in the systems simulated by the DIgSILENT shows the validity and accuracy of analysis. The AC/DC hybrid power system shows better dynamic performance and becomes stable more quickly than AC power system after fault. The damping and synchronizing torque coefficients are calculated for both systems to further explain the simulation results.

Nowadays, the conventional AC power grid is transforming rapidly with the introduction of renewable energy resources and high-voltage direct current (HVDC) links. HVDC links are efficient for long-distance transmission. For power systems with HVDC links, rotor angle stability is a crucial aspect in the system stability. This paper presents an overview of rotor angle stability analysis and control for hybrid AC/DC power systems with HVDC networks. Rotor angle stability analysis techniques for transient and small-signal stability are discussed in the paper. A detailed study on control strategies are also discussed for different types of network structures. According to the review, wide range of methods can be applied for rotor angle stability control, however all algorithms have their own advantages and disadvantages. Therefore, best algorithm should be selected considering overall power network characteristics.

Many studies have been carried out to study the performance of nanocomposite in the past decade. It has been proved that nanocomposite has a superior performance in both electrical and mechanical tests. But the long-term performance study is still lack in this area. Since the conventional composite products have issues in long-term performance, it's meaningful to carry out more studies on the long-term performance of nanocomposite. In this study, two different kinds of nanocomposite specimens are prepared for comparison. The host matrix, which is epoxy resin, is filled with nano SiO 2 particles. The percentage loading are 1 wt% and 2 wt% respectively. The nano fillers are dispersed into the epoxy resin using planetary centrifugal mixing technique and degassed in vacuum. Accelerated aging method is applied to age the specimens using QUV accelerated weathering tester. The total aging time is 500 hours. AC breakdown strength test, surface partial discharge analysis and FTIR are carried out to evaluate the electrical performance of the specimens.

We investigate the mode propagation and coupling in multimode fibers, based on modeling the wave propagation through the coupled power equation. Using this model, the power evolution of the various propagating modes in fibers can be visualized and the impact of mode-dependent loss and mode coupling can be quantitatively analyzed.

Recent developments in single-ring hollow-core photonic crystal fibre (SR-PCF) have made possible robust single-mode guidance over a broad bandwidth [1]—an important attribute in many applications, for example high power delivery of laser light and ultrafast gas-based nonlinear optics. Here we report for the first time that these fibres can be designed to transmit just one circular polarisation state if they are twisted continuously during fibre drawing [2], forming a helical structure.

An optical transmission loop experiment over hollow-core fiber is demonstrated with 1.25Gb/s OOK, 40G DP-QPSK, 100G DP-QPSK modulation schemes over distances of 31.0 km, 74.8 km, 55.8 km respectively, using two fiber spans with 2.7 km and 3.5 km length.

We present an all-optical flexible disaggregated flat DCN architecture utilizing Hollow-Core Bandgap Fibre, reconfigurable 4×16/8×12 Spectrum Selective Switches and FPGA-based switch and interface intra/inter-blade cards enabling chip-level access while utilizing cut-through low-latency tuneable WDM/WDM-TDM.

We compare for the first time the intermodal coupling coefficient of conventional few-moded solid fibres and of hollow-core photonic bandgap fibres and analyse its main contributions. We show that loss reduction in HC-PBGFs also results in reduced coupling coefficients.

This study is aimed to investigate the effect of different processing techniques on dielectric strength of epoxy/SiO 2 nanocomposite. Two processing techniques included in this study are sonication and Thinky planetary centrifugal mixer. Sonication is one of the most widely used mixing techniques in nanocomposite preparation and is believed to provide a good dispersion. However, sonication will produce a lot of air bubbles when disperse the fillers into the epoxy resin which will increase the difficulty of the degassing process. These kinds of small air bubbles may not affect the mechanical properties significantly but may have effects on the dielectric properties. Thinky planetary centrifugal mixer is an innovation mixing technique which can achieve a uniform mixing, dispersal and deaeration in a short time. SiO 2 was mixed with epoxy resin directly using either sonication or Thinky mixing with 2 wt% loading and 5 wt% loading respectively. The mixing time is 20 minutes, 40 minutes, 60 minutes respectively. The same degassing process is applied to both sonication and Thinky mixing specimens. The degassing process includes a vacuum degassing process and a degassing program in Thinky mixer. Breakdown strength tests were then performed to evaluate the effect of processing techniques. Dynamic mechanical analysis was also performed on the samples prepared by Thinky mixer.

The heat management bottleneck drives the search for alternative approaches for energy-efficient information technologies. Temporal and spatial magnetic spin textures are of great interest, since their dynamics can occur with minimal dissipation. Typical examples include spin waves (magnons), which are the fundamental quasi-particle excitations of magnetically ordered systems, and skyrmions, which are spatial spin textures that that are stabilized by their distinct topology, and can behave as independent quasi-particles. In bulk helimagnetic systems it has been demonstrated at low temperatures that skyrmions can be efficiently manipulated via electric currents with ultra-low threshold current densities.

Wireless Sensor (WS) technology is emerging from indoor application to regional industries nowadays. Demand arises due to the expanding wireless networks and technical requirement in sensing and automation. Awareness from technology leaders have stimulated the trend to research and develop reliable wireless sensor applications to observe situation, monitor condition, harvest information and then feedback to central processing unit for analysis and archival. Wireless sensor is the promising technology with great potential. This article describes trending wireless sensor applications in three areas, ranging from personal service to regional application. These applications include pedestrian sensing for transportation, indoor individual tracking and remote smart probe for power grid feeders. Remote sensors are the key component. It operates remotely with the supports from limited intelligence within the associated low power microprocessor. With technological advancement in nano-sensors and low power chipsets, the potential of wireless sensor technology implementation is broadening.

Conventional Magnetic Particle Imaging (MPI) employs current-driven magnetic fields to scan the position of a Field-Free Point (FFP) throughout the desired Field of View (FOV). These oscillatory fields simultaneously induce readily-detectable emfs at harmonics of the drive frequency as superparamagnetic nanoparticles (SPNs) in the sample are forced to undergo non-linear variations in magnetization. High frequency and large amplitude drive fields are desirable in the context of image resolution, sensitivity, and scan rates. They are undesirable — and in fact are severely constrained — for applications where Health Safety considerations (such as limits on Specific Absorption Rates and Peripheral Nerve Stimulation [1,2]) must be respected. We are investigating an alternative approach to MPI scanner design that seeks to address these issues by separating the processes of FFP manipulation and SPN excitation.

This paper describes the architecture of a quadrotor and its linearized dynamic model. The attitude of the quadrotor in the model state-space variables can be calculated with rotational matrix formed from quaternions instead of finite small angular displacement approximation. Based on H ∞ continuous time control method, a state feedback controller is designed to control the translational position and heading of the quadrotor.

The study of the lifetime performance of polymeric insulator is often based on incomplete data. Researchers face challenges of not having long observation time to gather complete lifetime data in order to make prediction with certainty. In this paper, we are proposing to use the best fitting polynomial interpolation approach to determine the lifetime model and extrapolate information towards the age of polymeric insulators. To gather the information such as the change of concentration of chemical element of polymeric insulation due to multiple stress conditions, high temperature vulcanized (HTV) silicone rubber specimens were subjected to accelerated degradation using an Accelerated Weathering Tester (QUV). Each specimen was subjected to accelerated aging cycle in accordance to ASTM G154 cycle 4 for a total of 3000 hours. The aging cycle goes through a cycle of 70 °C and ultraviolet exposure at irradiation intensity of 1.55 W/m2 for eight hours followed by four hour condensation at 50 °C. Chemical element concentrations such as Carbon, Oxygen, Silicon and Aluminum were obtained and evaluated using a Scanning Electron Microscope (SEM) with energy dispersive x-ray (EDX). The concentrations of chemical elements are analyzed using polynomial interpolation method of multiple orders. First order to fifth order polynomial interpolation methods are investigated to determine the best fitting curve without significance divergence from the actual value or true value. The interpolation curve is used to estimate the age of an unknown aged sample. This investigation has revealed a novel method for determining a model that could describe the lifetime of polymeric insulators and extrapolation method for estimating the age for polymer insulator.

This study investigates the aging of high-temperature-vulcanized (HTV) silicone rubber insulator under multiple stress conditions. Silicone rubber specimens were subjected to accelerate degradation using an accelerated weathering chamber. The specimen was subjected to accelerated aging cycle in accordance to ASTM G154 cycle 4 for a total of 3000 hours. The aging cycle goes through a cycle of 70°C and ultraviolet exposure at irradiation intensity of 1.55 W/m2 for eight hours followed by four hours condensation at 50°C. Morphology examination and chemical characterization using Scanning Electron Microscope (SEM) and Fourier Transforms Infrared Spectroscopy (ATR-FTIR) method are performed on the specimen. In this study, the aging performance of the silicone rubber insulator and the interdependence between the stressed material and dielectric breakdown strength are also under investigation. The results in this paper show that there are clear trend developed in the interval plots of the chemical elements such as carbon, oxygen, silicon and aluminum. These results agree with the decrease in the dielectric breakdown voltage as the period of aging cycle increases. The results obtained in this work indicate that the chemical characterization methods combining with electrical testing method can be used an effective tool to quantify and understand the aging process of silicone rubber insulator.

Simulation of the electric field and potential distribution is widely performed in the design of high voltage composite insulators. This paper introduces and analysis of electric field distribution around the insulator under a 22kV high voltage AC (HVAC) transmission line. A two-dimensional model is built to calculate the electric field distribution in single phase system and another 2-D model is used to calculate the distribution under a three-phase HVAC transmission line. The effects of the metal ground pin are considered in the model and a comparison of the single phase system and three-phase system is given in the conclusion. The results show that electric field strength in a three-phase system is significant larger than a single phase system. The electric field fluxes are also affected by the ground pin and other two phases in a three-phase system.

We introduce LiPS, a new cost-efficient data and task co-scheduler for MapReduce in a cloud environment. By using linear programming to simultaneously co-schedule data and tasks, LiPS helps to achieve minimized dollar cost globally. We evaluated LiPS both analytically and on Amazon EC2 in order to measure actual dollar charges. The results were significant; LiPS saved 62-81% of the dollar costs when compared with the Hadoop default scheduler and the delay scheduler, while also allowing users to fine-tune the cost-performance tradeoff.

Water droplets that form on the surface of outdoor insulating materials have the ability to experience deformation when subjected to an external electric field. This paper aims at studying the electromechanical effect the droplet experiences when subdued to an external AC voltage. Single and multiple droplets were placed on a piece of insulating fiberglass between an energised and grounded copper electrodes and the voltage increased until flashover occurred. A simulated model has been completed on COMSOL, multi-physics software, to gather an understanding of the forces produced on the droplet due to the application of an external electric field. Thus far, the major force acting on the droplet is due to the Maxwell Stress, a force accompanied with the application of an electric field. The outcome of this study will aid the understanding of the electromechanical effects present on water droplets in an external electric field on hydrophobic surfaces.

This paper studies creeping discharge on hardwood timber under AC and DC positive and negative voltages. Experiments have been carried out on hardwood timber which is commonly used as supporting structure for overhead power distribution lines. Differences between AC, DC positive and DC negative discharges are investigated. Creeping discharges developed on the surface of the hardwood timber are recorded using highly sensitive and low light camera and the surface area of the discharges developed under different voltages are quantified by computing the surface area of the discharges. In addition, the breakdown time of hardwood timber is measured. Effects of increasing voltage, capacitive effects of creeping discharge have been studied. The results show that the breakdown time of hardwood timber in DC positive voltage is shorter than DC negative and AC voltages. Capacitive effects on the breakdown time are also studied in this paper. These results provide new insights into the role of creeping discharges leading to the breakdown of hardwood timber and the subsequent burning of the timber.

In this paper, a combined random vibration and thermal cycling fatigue time-to-failure (TTF) prediction analysis will be reported. The combined random vibration and thermal cycling (TC) loading profile employed in the study is a thermal cycle loading of -40°C to +125°C (1 hour cycle with 15 minutes dwell) with random vibration of 7.5GRMS. Random vibration is applied concurrently at the extreme temperature during dwell periods for 15 minutes. The test vehicle used has six (6) Plastic Ball Grid Array (PBGA) packages mounted on the PCB with 12 mounting holes. Full model was adopted for this work. The 3D model consists of a PCB with edge connector, 1936 solder joints per package, BT substrate, silicon die and mold compound. A global model with solder cuboids and a local “submodel” with fine mesh was analyzed separately for temperature cycling analysis. A stress versus failure cycles (S-N) curve was formulated by performing a SN curve test on SAC305 test specimens. Combined loading test with TC from -40°C to +125°C and random vibration of 7.5 GRMS was conducted. Correlation between the experimental test results and the combined loading life prediction results are made in this paper.

In optically active materials and devices, the plane of vibration of linearly polarized light is rotated due to different phase indices of left- and right-circularly (LC and RC) polarized light, i.e., there is circular birefringence. Optical fibers with high circular birefringence are able to maintain circular polarization states against external perturbations such as bending and mechanical stress. In this paper, we present theoretical and experimental analysis of optical activity in twisted photonic crystal fibers (PCFs).

Power distribution and transmission networks widely adopt composite insulators for the overhead power line applications. The premature failure of these insulators due to the high electric field induced in them has become a major disappointment in the recent years. In this paper, an 11kV composite insulator is modelled in a three phase high voltage environment, and the induced electrical field is studied using finite element analysis. To reduce the computational time and resources, a simplified geometry for the insulator is also proposed. The electric field calculations are used to understand the importance of using a three phase supply in computational and experimental analysis of insulators, which we determine is more accurate than using a single phase supply.

Polymeric insulators are widely used in electrical power system in particular transmission and distribution lines. Silicon rubber is a high performance polymeric material with superior insulation property and physical properties such as light weight. This paper presents the effects of ultra violet radiation and heat on the aging of silicon rubber and estimates the lifetime of insulators made of this material based on chemical bounds percentage at different exposure times. Experimental works were performed on samples collected from a 22KV silicone rubber insulator. The specimens were subjected to accelerated aging cycles using an Accelerated Weathering Tester (QUV) at 50°C and UVA exposure of 340nm at the irradiation intensity of 0.68W/m2 for up to 3000 hours. A series of tests were conducted on the samples using instruments that measure different aspects of aging. The degradation was examined using a Scanning Electron Microscope (SEM) and a Fourier Transforms Infrared Spectroscopy (ATR-FTIR). In addition, the color change of the specimens was measured by CHROMA Meter (CR-300). In this paper, we show that the remaining service life of the insulators can be estimated using the chemical measurements and color factors by making comparisons between new, aged and totally damaged specimens. The 3D scatterplot for the obtained data show a clear trend and timeline on how a new specimen degrades over time and eventually leads to complete failure. This information provided by the 3D scatterplot could be used to estimate the remaining life of silicone rubber insulators.

The power distribution and transmission networks in many countries use wood for fabricating service poles for the overhead power lines. In this paper, we model a wooden pole used in an 11kV three phase distribution system. We use this model to study the electric fields induced in the wooden supporting structures, in order to determine the possibility of micro arcing inside them, using Finite Element Analysis. The three dimensional model takes into consideration both the resistive and capacitive properties, and closely resembles the actual pole. We show that the electric field distribution of the utility pole changes significantly with the change of weather conditions, and the size of the air gap at the wood-metal interface where the electric field is at its maximum. Also, we show that the electric field in this gap can be reduced significantly by modifying the king bolt using an epoxy coating. This reduction will minimize the chance of micro arcing inside the air gap near the bolt, which will reduce the long term degradation of the wooden structure.

This paper focuses on applying Super-Resolution (SR) on Photothermal images of the 4.9μm Red Polystyrene Beads (RPB) obtained from a Photothermal imaging (PTI) system. Since the images acquired from the PTI system are noisy and it can be costly to achieve a higher resolution from the hardware side, it is efficient to do so by SR. In this paper, the experimental procedures are presented and the SR shows significant improvement in the processed images, mainly in terms of resolution, sharpness and contrast.

The cost and time of deploying HPC applications on clouds is a problem. Instead of conducting their research discipline specialists are forced to carry out activities for application deployment, publication and ease of access. In response, a new approach for HPC application deployment and access in clouds is proposed. The major innovations are a new approach to deploying and executing HPC applications on IaaS and PaaS clouds, and exposing HPC applications as services. Through three case studies this paper demonstrates the feasibility and effectiveness of the proposed approach that could lead to the building of a SaaS library of discipline-oriented services evocable through user friendly, discipline specific interfaces. The new approach will reduce the time and money needed to deploy and expose discipline HPC applications.

This paper present the modeling of seawater acoustic channel to yield the optimum carry frequency for autonomous underwater vehicle (AUV) wireless communication system. Many underwater acoustic wireless communications had been explore whereby the exploration is mainly done for a specific distance. However, the wireless communication distance of an AUV with its control vessel varies due to the task at certain depth. This current AUV is design with an operation depth of 0 to 2000m. Therefore, the existing model had limitation when the operation depth varies base on the task assignment. This is because the optimum frequency to noise ration varies with respect to the distance of the transmission. To surmount the existing modeling method, this paper presents an improved method to identify the optimum carry frequency for AUV wireless communication system. Mathematical model with the relation of frequency, distance and noise is formulated and simulation is carried out to tabulate the optimum frequencies at various distances. From the frequency band, the average frequency is identified as the optimum transmission carries frequency. The identified frequency will be used for further hardware development.

Flashover is damaging to the power transmission and distribution system. In this paper, correlation coefficient as a measure of nonlinearity is employed to analyze the leakage current signals generated from heavily polluted insulators for flashover prediction purpose. Data is generated with dry and wet conditions together with various supply voltages. By calculating the correlation coefficients between the supply voltages and the leakage currents, some patterns are found which may help identify the status of insulators.

Inter-domain routing in today's Internet is plagued by security and reliability issues (e.g., prefix hijacking), which are often caused by malicious or Byzantine misbehavior. We argue that route selection policies must move beyond static preferences that select routes on the basis of static attributes such as route length or which neighboring AS is advertising the route. We prove that route convergence in the presence of Byzantine misbehavior requires that the route selection metric include the dynamics of route updates as a primary component. We then describe a class of simple dynamic policies which consider the observed “ages” of routes. These gerontocratic policies can be combined with static preferences and implemented without major infrastructural changes. They guarantee convergence when adopted universally, without sacrificing most of the flexibility that autonomous systems enjoy in route selection. We empirically demonstrate that even if adopted unilaterally by a single autonomous system, gerontocratic policies yield significantly more stable routes, are more effective at avoiding prefix hijacks, and are as responsive to legitimate route changes as other policies.

All-digital phase-locked loops (ADPLLs) have recently become more popular as possible alternatives to conventional analog charge-pump-based PLLs [1]. Currently, most of the ADPLLs are based on a time-to-digital converter (TDC) utilizing inverter delay chains. There have been tremendous efforts to improve TDC performance, i.e., maximizing resolution and reducing power consumption, but they normally require additional complex circuits.