Novel Compression Algorithm Based on Sparse Sampling of 3-D Laser Range Scans

Cataloged from PDF version of article.Three-dimensional models of environments can be very useful and are commonly employed in areas such as robotics, art and architecture, facility management, water management, environmental/industrial/urban planning and documentation. A 3-D model is typically composed of a large number of measurements. When 3-D models of environments need to be transmitted or stored, they should be compressed efficiently to use the capacity of the communication channel or the storage medium effectively. We propose a novel compression technique based on compressive sampling applied to sparse representations of 3-D laser range measurements. The main issue here is finding highly sparse representations of the range measurements, since they do not have such representations in common domains, such as the frequency domain. To solve this problem, we develop a new algorithm to generate sparse innovations between consecutive range measurements acquired while the sensor moves. We compare the sparsity of our innovations with others generated by estimation and filtering. Furthermore, we compare the compression performance of our lossy compression method with widely used lossless and lossy compression techniques. The proposed method offers a small compression ratio and provides a reasonable compromise between the reconstruction error and processing time

A compression method based on compressive sampling for 3-D laser range scans of indoor environments

When 3-D models of environments need to be transmitted or stored, they should be compressed efficiently to increase the capacity of the communication channel or the storage medium. We propose a novel compression technique based on compressive sensing, applied to sparse representations of 3-D range measurements. We develop a novel algorithm to generate sparse innovations between consecutive range measurements along the axis of the sensor's motion, since the range measurements do not have highly sparse representations in common domains. Compared with the performances of widely used compression techniques, the proposed method offers the smallest compression ratio and provides a reasonable balance between reconstruction error and processing time. © 2011 Springer Science+Business Media B.V

URANS-Based Prediction of Vortex Induced Vibrations of Circular Cylinders

Vortex induced vibrations (VIV) are highly nonlinear due to three different frequencies involved in the process; fluid force frequency, vortex shedding frequency and oscillation frequency. It is computationally complex to solve such a chaotic fluid flow but recent progress in numerical algorithms, turbulence models and computer capabilities have made it easier to approach the problem with a nonlinear approach. These developments have paved the way to approach the problem with the simple equation of motion of Newton’s law and when coupled with URANS, which is a commonly used method in solving problems related to fluid flow, the highly nonlinear problem of vortex induced vibrations become solvable. The existing literature computationally can only handle flows for Re>10,000-12,000 but the numerical methodology adopted in this study furthers this limitation. The numerical algorithm is first tried for a stationary cylinder and the boundary layer separation is investigated for higher Re. The generated results are found to be satisfactory to proceed solving for VIV at high Re. The solution strategy is tested in a wide range of Reynolds number with different springs and damping coefficients. Satisfactory agreement is found with the experiments for a cylinder in VIV. The shortcomings of the computational work and why these limitations arise are tried to be explained using the experimental results and the existing mathematical models

Cholangiocarcinoma in Magnetic Resonance Cholangiopancreatography and Fascioliasis in Endoscopic Ultrasonography

Fascioliasis is a worldwide zoonotic infection with Fasciola hepatica and Fasciola gigantica. The zoonoses are particularly endemic in sheep-raising countries and are also endemic in Iran. Typical symptoms that may be associated with fascioliasis can be divided by phases of the disease, including the acute or liver phase, the chronic or biliary phase, and ectopic or pharyngeal fascioliasis. Cholestatic symptoms may be absent, and in some cases diagnosis and treatment may be preceded by a long period of abdominal pain, eosinophilia and vague gastrointestinal symptoms. We report a case with epigastric and upper quadrant abdominal pain for the last 4 years, with imaging suggesting cholangiocarcinoma. Considering a new concept of endoscopic ultrasonography, at last F. hepatica was extracted with endoscopic retrograde cholangiography

The analysis of wearable motion sensors in human activity recognition based on mutual information criterion [Karşilikli bilgi ölçütü kullanilarak giyilebilir hareket duyucu sinyallerinin aktivite tanima amaçli analizi]

Selecting a suitable sensor configuration is an important aspect of recognizing human activities with wearable motion sensors. This problem encompasses selecting the number and type of the sensors, their position on the human body. In earlier works, researchers have used customized sensor configurations, and compared them with others in terms of the activity recognition rate. However, it is clear that these comparisons are dependent on the feature sets and classifiers employed. In this study, employing mutual information measure, sensor configurations are determined with respect to the time-domain distributions of the raw sensor measurements. The most informative axes of the accelerometers, gyroscopes, and magnetometers fixed at several locations on the human body are detected. © 2014 IEEE

The prevalence of gastroesophageal reflux disease among hospital employees

Quantitative estimate of the actual prevalence of the gastroesophageal reflux disease (GERD) is difficult to obtain because most of the patients with heartburn have intermittent symptoms. The aim of this study was to assess the frequency of typical and atypical symptoms suggesting GERD to investigate the association of habits and social conditions reported to lead to reflux in the employees of hospital. A total of 2037 collected forms were assessed. The prevalence of GERD was found to be 21.7% (442). The prevalence of symptoms other than heartburn in employees with and without GERD symptoms were 6.6% versus 3.4% (P 30 kg/m(2) were independent risk factors associated with GERD symptoms. Age, alcohol, coffee, tea, and tobacco smoking do not seem to be risk factors for reflux