The Reynolds stresses in a three-dimensional turbulent boundary layer were examined using octant analysis. The representative flow was a pressure driven, three-dimensional turbulent boundary layer on the leeside (x/L=0.76-0.78, φ=105°-130°) of a 6:1 prolate spheroid at 10° angle of attack. The Reynolds number for the flow was Re_L=4.2x10⁺⁶. The LDV data of Chesnakas, Simpson, and Madden (1994) were the basis of examination. This data set employed a post-processing technique for refining the radial location of the measurements. A least-squares fit of the Spalding wall law was used to both correct the measurement locations and estimate the wall shear stress. This paper presents a previously unpublished assessment of the technique. Octant analysis was performed on the corrected data under free-stream and wall-collateral coordinates. (The wall-collateral coordinate system is aligned with the mean tangential velocity in the buffer-layer.) The octant analysis led to the development of a structural model that extends the sweep/ejection process to three dimensions. Ejections and sweeps produce w' through the same mechanism that produces u'; they transport fluid across a spanwise velocity gradient. The model's results remain consistent with coordinate rotation. The model also describes the asymmetries that evolve between ejections and sweeps with spanwise fluctuations (w') of opposite sign. These asymmetries cause non-zero u'w' and v'w' in the buffer layer. Comparison of the two coordinate systems reveals that wall-collateral coordinates provides a simpler foundation for octant analysis. The sweep and ejection octants maintain a nearly equal distribution of velocity events throughout the buffer and lower log layers. Also, the spanwise velocity profile monotonically decreases to a constant value at the boundary layer edge, simplifying application of the sweep/ejection model to spanwise fluctuations. Comparison with other 3DTBL experiments suggests that the wall-collateral coordinates are more closely aligned with the quasi-streamwise vortex structures than free-stream coordinates. The octant analysis also reveals structural behavior consistent with the four mechanisms revealed by the direct numerical simulation of Sendstad and Moin (1992). / Master of Science

This thesis deals with the evaluation of the geographical location of the Internet using delay and implementating method Octant. The first part is devoted to familiarization with the principles of evaluation of the physical position of the stations on the Internet, with a focus on active methods for IP Geolocation. Here it is more space devoted to geolocation Octant algorithm and a more detailed explanation of its principles. At the end of the first part is also familiar with the experimental network PlanetLab. The second part describes the design and implementation of the program in programming language C#, which locates the searched local station with mentioned localization algorithm Octant. Description realization is accompanied by explained examples of the classes with a detailed explanation. Here are also the results of the methods on selected IP addresses of stations with known locations to detect errors or deviations of method from the actual position of searched station. At the end of this section is a comparison with other active as well as passive geolocation methods.

Master of Science / Department of Computing and Information Sciences / David A. Gustafson / Octant analysis, when combined with properties of the multivariate central limit theorem and multivariate normal distribution, allows finding a reasonable grasping point on an unknown novel object possible. This thesis’s original contribution is the ability to find progressively improving grasp points in a poor and/or sparse point cloud. It is shown how octant analysis was implemented using common consumer grade electronics to demonstrate the applicability to home and office robotics. Tests were carried out on three novel objects in multiple poses to determine the algorithm’s consistency and effectiveness at finding a grasp point on those objects. Results from the experiments bolster the idea that the application of octant analysis to the grasping point problem seems promising and deserving of further investigation. Other applications of the technique are also briefly considered.

The thesis discusses about modern geolocation methods and it describes the basic principles of their work. The work is divided into 2 parts - the theoretical one and the practical one. The first part of the thesis is focused on the description of these methods and on the explanation of its basic concepts which are used for determining of the physical position of the station according to its IP address. The second more extensive part of the work focuses on the description of the realization of algorithm in the Octant method in the programming language of Java and its use in the experimental net of PlanetLab. One important thing is to create a set of reference points and targets, which are necessary for the testing of the whole algorithm of the Octant Method. The results of estimated accuracy of target location obtained by the Octant method and their comparison with the results obtained by active methods of CBG, SOI and with the passive method of GeoIP are listed at the end of this work.

Dissertation thesis deals with methods for finding the location of the device in the Internet, based on knowledge of the IP address. The process is called IP geolocation and is currently solved by geolocation databases or by measurement of network properties to the IP address. The disadvantage of nowadays geolocation databases is an incorrect information about some locations, because they can be in large distance from correct position. The aim of the thesis is to develop a method for verification of a position from geolocation database using delay measurement. Because of it, there is a detail analysis of influence of partial delays on the distance estimation accuracy, calculated using measured delay between the landmark and the target IP address. For the same reason, long-term delay measurement was performed, where the IP geolocation accuracy was compared using calibration data from previous measurements. On this background, Cable Length Based Geolocalisation (CLBG) method is proposed. Principle of this method is built on the properties of partial delays, which depend on the length of transport media. Firstly, the method measures round trip time (rtt), which is subsequently lowered by intermediate devices and end stations delay. The geographical distance is estimated using signal speed in the transport media. Further, the winding media parameter is established, which is used to determine a constraint around the landmark. The intersection of all constraints defines the area, where the target IP is. The IP geolocation using CLBG gives better results than simpler methods (ShortestPing, GeoPing and SOI), in comparison with more advanced methods (CBG and Octant) the accuracy is similar. The disadvantage of the CLBG method is the size of region, where the target lies, but this is due to its purpose. The position found in geolocation database can be checked by evaluation if it lies in the region.