Incessant focal atrial tachycardia (FAT) is the most common cause of tachycardia-induced cardiomyopathy in pediatric patients and is usually a reversible condition with effective management of tachycardia, either with medical treatment or ablation. These patients may be misdiagnosed, potentially leading to inappropriate treatment. Diagnosis is often late and should always be suspected in patients with congestive heart failure and unexplained persistent tachycardia. Para-Hisian atrial tachycardia is not an uncommon type of FATs; however, catheter ablation of anterior atrial septum-ATs has been a challenge because of its proximity to the AV node and the complex anatomy of its region.
This paper examines the interaction of pack ice with a floating production storage and offloading unit (FPSO). The vessel maintains position using a thruster-assisted turret mooring. An ice dynamics model is used to conduct numerical simulations of the interaction of the ice cover with the vessel. The model is based on solving equations describing the conservation of mass and linear momentum together with a failure criterion for the ice cover. The vessel is modelled as a three-degrees-offreedom rigid body. The results give an evolution of the stresses and deformation of the ice cover, ice forces, and offsets of the vessel. Ice conditions and FPSO characteristics typical for the Grand Banks were used in the simulations. The results show a strong dependence of ice forces and vessel offsets on ice concentration. The roles of ice floe size and ice thickness were less significant. The conclusions indicate that for the ice conditions considered, vessel offsets would fall well within the operating capabilities of a typical Grand Banks FPSO.
The presence of floating ice in northern regions bears significant economic, environmental, and social implications. Navigation is one of the areas where the influence of floating ice is particularly evident. The history of ice threats to navigation and hardships experienced by early mariners are well known. At present, even with all the new technologies, ice can pose serious challenges. A major threat arises when ice around a ship starts to converge. The compression or ice pressure builds up if wind and water currents drive the ice cover against a land boundary. The ice cover compresses and ice accumulates to form ridges. If a ship is caught in such a situation, pressures on the hull will be high. Additionally, the ridges can introduce serious impediments to ship progress. Consequently, ice resistance would dramatically increase, and the ship can become beset. In extreme cases, ships can be damaged, and smaller vessels can be completely lifted onto the ice. To understand how ice interacts with ships, we must start with ice properties and characteristics of ice covers. Ice ridges, for example, may represent formidable obstacles to ships. The way those ridges form and their properties determine the level of resistance that ships may encounter. Although the effects of ice pressure are important over all Arctic and northern waters, the focus of this discussion is on the Canadian experience. The particular conditions that lead to ice pressure build-up and the impact on shipping at various specific locations in Canada are surveyed. The discussions conclude with a description of a Captain's experience in dealing with ice pressure on the Great Lakes.
The present paper reports on comparisons between results from ice basin tests and numerical simulations. The tests were conducted in the model ice basin of the National Research Council Canada in St. John’s, Newfoundland. Those tests examined the performance of a vessel controlled by a dynamic positioning (DP) system in managed ice conditions at a scale of 1:40. A numerical ice dynamics model was used to simulate ice basin test conditions. The results indicate that surge direction thrust and ice force are in good agreement. Ice basin measurements, however, produced higher sway-direction ice forces and yaw-direction moments. It appears that the treatment of sidewall boundaries and the resulting confinement of the ice cover may have contributed to that discrepancy. An additional contribution may be due to differences between the DP algorithms, which were used in the numerical simulations and ice basin tests. Numerical simulations also examined the role of floe shapes. The results indicate that floe shapes obtained from field observations reduce sway-direction ice forces and yaw-direction moments below values obtained when using near-square floe geometries.
Brugada syndrome is an autosomal dominant arrhythmogenic disease associated with an increased risk of ventricular fibrillation and sudden cardiac death. The mainstay of treatment in high-risk patients is an implantable cardioverter-defibrillator (ICD), however radiofrequency ablation has been proposed over the past decade as an additional therapy in patients with recurrent ICD firing. We report a case of Brugada syndrome with an electrical storm which was successfully managed by radiofrequency ablation.
It is crucial to find methods that analyze large amount of data captured by cameras and/or various sensors installed all around us. Machine learning becomes a prevailing tool in analyzing such data that signifies behavioral characteristics of human beings. Gait as an identifier for use in individual recognition systems has respective and almost certainly unique key features for each person including centroid, cycle length and step size. Gait is sometimes preeminent suited to recognition or surveillance scenarios. It might be used in the identification of females who are wearing veils in some countries without critical social issues. The objective of this project is to predict accurately one-dimensional coordinates of normalized n-component vectors representing two-dimensional silhouettes in order to identify individuals at a distance without any interaction and obtrusion. Varied algorithms are further incorporated into walk pattern analysis to adoptively improve gait recognitions and classification. The results are reported reasonable identification performance as compared to several machine learning methods.
Matching thermal face images as a method of biometric authentication has gained increasing interest because of its advantage of tracking a target object at night and in total darkness. Therefore, for security purposes, it has become highly favourable and has extensive applications, for instance, in video surveillance at night. The aim of this study is to present a simple and efficient deep learning model, which accurately predicts person identification. A pre-trained Convolutional Neural Network (CNN) is employed to extract the features of the multiple convolution layers of the low resolutions' thermal infrared images. To run the program and evaluate the performance, we use a sample of 1500 resized thermal images, each with resolution 181×161 pixels. The sample comprises of images that were captured within different time-lapse and with diverse emotions, poses and lighting conditions. The proposed approach is effective compared to the state-of-the-art thermal face recognition algorithms and achieves impressive accuracy of 99.6% with less processing and training times.
Background and Objective: Natural walk and topological analysis of human being have respective and certainly unique key features that allow identifications when other biometric techniques are not visible.The objective of this paper is to draw attention towards a simple and novel feature extractor for gait recognition that is based on a deep learning approach.Materials and Methods: Different from conventional ways and means, the gait is designated as regular and intermittent motion taken out directly from silhouettes.Before the use of convolutional neural network to learn human gait representations, two important data pre-processing stages are enforced to enhance the characteristics of gait patterns obtained from grayscale images.Results: The proposed gait recognition approach achieves impressive results in terms of training/validation accuracy and mean square errors.Conclusion: The conducted experimental outcomes report competitive performance as compared to many traditional machine learning methods and previous deep gait models specifically for the case of low-image resolutions and large-scale dataset of input images.
The present paper reports on comparisons between results from ice basin tests and numerical simulations. The tests were conducted in the model ice basin of the National Research Council Canada (NRC) in St. John’s, Newfoundland. Those tests examined the Dynamic Positioning (DP) of a vessel in managed ice conditions at a scale of 1:40. A numerical model, which was developed by the NRC over the past few years, was used to simulate ice basin test conditions. The results indicate that surge direction thrust and moments are in good agreement. The conclusions address the effects of ice channel width and floe shapes.
This paper reviews a simple and compact dielectric annular grating antenna. The proposed antenna made of high resistivity silicon using silicon platform. The antenna is fed through Dielectric image guide (DIG), with a maximum gain of 18 dB, and wide bandwidth more than 7 GHz which is suitable for commercial applications, such as mobile radio, short range wireless communication and W-band applications in Millimeter Applications requiring high Gain, efficiency, data rate, and large bandwidth. The main features of the proposed antenna that is achieved by designing low-cost, compact size, and ease of fabrication and integration. The simulation gain of the antenna is 18 dB at 102 GHz with radiation efficiency better than 95%.
AbstractThe paper examines ice compression (or pressure) build-up, which may pose a threat to navigation, over various zones of the Canadian Arctic and sub-Arctic waters. The results were obtained from a multi-year program conducted at the National Research Council of Canada. The objective of that program is to quantify the risks to navigation posed by compressive ice, and to develop predictive tools to aid shipping operations in an ice environment. The work consisted of a number of activities, including: the development of an ice dynamics model tailored for high-resolution simulations of ice cover drift and deformation; creating a database of besetting events and analysis of the conditions that influence the risk of besetting; hindcasting of ice and other environmental conditions that led to besetting over various geographic regions; and the development of forecasting tools to support offshore and shipping operations and training mariners. The present paper documents the governing equations of the ice dynamics and ridging model and discusses the high-resolution implementation that makes it possible to predict the risk of vessel besetting. A case of ice compression that took place in the southern Beaufort Sea is examined. The critical values of ice pressure and ridge thickness that posed a threat to vessels during that event were found compatible with estimates corresponding to besetting events in the Gulf of St. Lawrence and Frobisher Bay.
AbstractThis paper examines the response of a drillship to the action of an ice cover undergoing a gradual change of direction of motion. For effective stationkeeping, the drillship must continuously change its heading to face the oncoming ice. The simulations consider a vessel that maintains position using Thruster-Assisted Mooring (TAM). A turret mooring system resists the surge and sway movements, while the thrusters act to correct the heading. The simulations of ice deformation and drift solve equations that describe conservation of mass and momentum, and a failure criterion. The drillship is treated as a three-degrees-of-freedom (surge, sway and yaw) rigid body. The results give distributions of ice drift, deformation and stresses around the vessel as well as the forces and offsets of the drillship. The resulting peak ice forces and moments on the drillship show clear dependence on the rate of change of ice drift direction. As may be expected, ice forces and moments increase for high rates. They also increase for higher ice velocities. Analysis of the results shows that the ratio of the length of the drillship to the radius of curvature of ice drift trajectories can be used to estimate ice forces and moments in an environment of changing ice drift direction. The present work additionally included a cursory examination of the effects of ice cover conditions; namely ice thickness and the existence of ridge fragments and icebreaking tracks, which are often formed as part of ice management operations.
Abstract In northern regions, ice forces, or actions, must be considered in the design of structures such as light piers, bridge piers, and offshore platforms. Estimates of ice forces in Canadian waters are usually obtained by consulting design standards such as those developed by the International Organization for Standardization (ISO) and the Canadian Standards Association (CSA). These design standards draw on available analytical formulae. Field measurements are available from several sources that suggest reasonable agreement with analytical results for simple cases involving wide structures. One of the remaining uncertainties in estimating design loads, however, is the contribution of force imposed below the waterline due to unconsolidated keels of ice ridges. Only cursory guidance is provided by the standards associations and their analytical design equations. Close inspection of those formulae show that force estimates can become excessive in situations where the expected keel depth is great compared to the designed structure width. Such scenarios would be expected in offshore oil and gas operations where drilling risers, jack-up legs, and even jacket structures may be exposed to ice ridges. The present work examines available approaches for evaluating ridge keel forces, including passive pressure calculations. The processes of ice rubble failure and the corresponding stress distributions are considered in the context of classical soil mechanics applied in geotechnical engineering. Design standards are also used to calculate ice forces for a range of ridge keel properties, keel geometries, and structure design widths. Field measurements from the Norströmsgrund lighthouse and the offshore Molikpag caisson are then examined and compared to the forces obtained using these approaches. The authors conclude that the shape factor adopted in ISO 19906 plays an important role in calculations considering narrow structures and deep keels. It is also shown that the sensitivity of ridge keel load calculation to geometric factors varies considerably with structure width. Furthermore, an absence of real world data from ridge keel interactions with very narrow structures precludes validation of present models in these situations and should be the focus of data collection and model refinement.
Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. Catheter ablation of atrial fibrillation plays an important role in the management of AF. Radiofrequency ablation is widely used in practice all over the world. Cryoablation has emerged as an alternative method for AF ablation. The FIRE and ICE trial was a non inferiority, multicentre, randomized trial that compared between the two modalities and proved cryoablation to be non inferior to radiofrequency in terms of efficacy and safety. However, the rate of AF recurrence was markedly high in both arms of the study.
Discusses the Automatic Radio Frequency Techniques Group (ARFTG), a technical organization interested in all aspects of RF and microwave test and measurement. ARFTG was originally set up in 1972 to help end-users get the most from the latest generation of test and measurement equipment.
Improving learning outcome has always been an important motivating factor in educational inquiry.In a blended learning environment where e-learning and traditional face to face class tutoring are combined, there are opportunities to explore the role of technology in improving student's grades.A student's performance is impacted by many factors such as engagement, self-regulation, peer interaction, tutor's experience and tutors' time involvement with students.Furthermore, e-course design factors such as providing personalized learning are an urgent requirement for improved learning process.In this paper, an artificial neural network model is introduced as a type of supervised learning, meaning that the network is provided with example input parameters of learning and the desired optimized and correct output for that input.We also describe, by utilizing e-learning interactions and social analytics how to use artificial neural network to produce a converging mathematical model.Then students' performance can be efficiently predicted and so the danger of failing in an enrolled e-course should be reduced.
AbstractThe ability of a drillship to maintain its heading to face oncoming pack ice is crucial under situations involving changes in pack ice drift direction. The performance of a vessel employing a Thruster-Assisted Mooring (TAM) system under such conditions is examined in this paper. Numerical simulations were used to determine the stresses and deformations within the moving pack ice cover, as well as the response of a drillship with characteristics similar to published information on Stena's DrillMAX. A turret mooring system is assumed to resist surge and sway direction offsets, but provides no restoring moment to vessel's yaw. In such system, thrusters would be used to provide damping and to apply the corrective moment that controls the heading of the vessel. The pack ice cover is assumed to consist of managed floes of sizes ranging from 30 m to 50 m, and with a uniform thickness of 1 m. The ice cover moves against the vessel at a steady velocity of 0.5 m/s. Simulations start with the vessel at a heading inclined to the oncoming ice direction. The simulations predict the evolution of the distributions of ice thickness and pressures, ice forces and moments, as well as the response of the vessel. Test cases examined a range of values of the initial heading of the vessel and limits on available yaw moment that can be generated by the thrusters. The results illustrate the manner in which the vessel can correct its heading, and give the corresponding offsets, ice forces and moments.