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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
261

Computation Offloading and Service Caching in Heterogeneous MEC Wireless Networks

Zhang, Yongqiang 04 1900 (has links)
Mobile edge computing (MEC) can dramatically promote the compu- tation capability and prolong the lifetime of mobile users by offloading computation- intensive tasks to edge cloud. In this thesis, a spatial-random two-tier heterogeneous network (HetNet) is modelled to feature random node distribution, where the small- cell base stations (SBSs) and the macro base stations (MBSs) are cascaded with resource-limited servers and resource-unlimited servers, respectively. Only a certain type of application services and finite number of offloaded tasks can be cached and processed in the resource-limited edge server. For that setup, we investigate the per- formance of two offloading strategies corresponding to integrated access and backhaul (IAB)-enabled MEC networks and traditional cellular MEC networks. By using tools from stochastic geometry and queuing theory, we derive the average delay for the two different strategies, in order to better understand the influence of IAB on MEC networks. Simulations results are provided to verify the derived expressions and to reveal various system-level insights.
262

An Integrated Approach for Predicting Nitrogen Status in Early Cotton and Corn

Fox, Amelia Ann Amy 09 May 2015 (has links)
Cotton (Gossypium hirsutum L.) and corn (Zea mays L.) spectral reflectance holds promise for deriving variable rate N (VRN) treatments calibrated with red-edge inflection (REI) type vegetation indices (VIs). The objectives of this study were to define the relationships between two commercially available sensors and the suitable VIs used to predict N status. Field trials were conducted during the 2012-2013 growing seasons using fixed and variable N rates in cotton ranging from 33.6-134.4 kg N ha-1 and fixed N rates in corn ranging from 0.0 to 268.8 kg N ha-1. Leaf N concentration, SPAD chlorophyll and crop yield were analyzed for their relation to fertilizer N treatment. Sensor effects were significant and red-edge VIs most strongly correlated to N status. A theoretical ENDVI index was derived from the research dataset as an improvement and alternative to the Guyot’s Red Edge Inflection and Simplified Canopy Chlorophyll Content Index (SI).
263

Development and Loss of Porosity in the Lower Cretaceous (Aptian-Albian) Sligo Formation Shelf Edge Reef, South Texas

Aina, Eyitayo David 09 December 2011 (has links)
Approximately 37 m (120 ft) of core was studied with the objective of evaluating and documenting the development and loss of porosity in the dry Mobil McElroy-1 well (Lower Cretaceous Aptian – Albian Sligo Formation). Core slabs were described and thin section samples, taken every 1.5 m (5 ft), were stained and analyzed under standard petrographic, cathode luminescence, confocal and scanning electron microscopes. The main conclusion is that average porosity significantly reduced with depth. Carbon and oxygen isotope values obtained for 20 samples show that the main pore-occluding diagenetic environment was meteoric with most samples having relatively low delta18O (-3.1%o to -6.7%o V- PDB) values. Early through late stage medium (1 mm – 3 mm) to large (> 3 mm) calcite and nonerroan dolomite jointly contributed to more than 10% of primary porosity loss. This study significantly contributes to the understanding of the Sligo Formation and promotes development of natural gas resources.
264

Effectiveness of Crop Reflectance Sensors on Detection of Cotton (Gossypium Hirsutum L.) Growth and Nitrogen Status

Raper, Tyson Brant 06 August 2011 (has links)
Cotton (Gossypium hirsutum L.) reflectance has potential to drive variable rate N (VRN) applications, but more precise definitions of relationships between sensor-observed reflectance, plant height, and N status are necessary. The objectives of this study were to define effectiveness and relationships between three commercially available sensors, and examine relationships of wavelengths and indices obtained by a spectrometer to plant height and N status. Field trials were conducted during 2008-2010 growing seasons at Mississippi State, MS. Fertilizer N rates ranged from 0-135 kg N ha-1 to establish growth differences. Sensor effects were significant, but sensors monitoring Normalized Difference Vegetation Index (NDVI) failed to correlate well with early-season N status. Wavelengths and indices utilizing the red-edge correlated most strongly with N status. Both Guyot’s Red Edge Index (REI) and Canopy Chlorophyll Content Index (I) correlated consistently with N status independent of biomass status early enough in the growing season to drive VRN.
265

Characteristics of Soil Heterogeneity and Effectiveness of Crop Reflectance on Detection of Corn (Zea mays L.) Nitrogen Status

Hubbard, Ken J 12 May 2012 (has links)
Spatial variations in soil properties can directly affect Nitrogen status of corn (Zea mays L.) and decrease efficiency of uniform fertilizer N applications. The objective of this study was to assess the spatial variations of soil properties and measure the effect on corn Nitrogen status through canopy reflectance. Field trials were conducted in 2010 and 2011 on a producer’s field west of Yazoo City, MS that contained high in field variability. Soil physical and chemical properties all exhibited moderate to high spatial dependency during both years of this study. Vegetative indices were derived from canopy reflectance values and indices utilizing the red-edge were the strongest and most consistent descriptors of tissue N percent and whole plant N uptake. The Canopy Chlorophyll Content Index (I) shows the greatest potential of assessing variations of corn Nitrogen status among the indices tested.
266

Evaluation of hyperspectral band selection techniques for real-time applications

Butler, Samantha 10 December 2021 (has links) (PDF)
Processing hyperspectral image data can be computationally expensive and difficult to employ for real-time applications due to its extensive spatial and spectral information. Further, applications in which computational resources may be limited can be hindered by the volume of data that is common with airborne hyperspectral image data. This paper proposes utilizing band selection to down-select the number of spectral bands to consider for a given classification task such that classification can be done at the edge. Specifically, we consider the following state of the art band selection techniques: Fast Volume-Gradient-based Band Selection (VGBS), Improved Sparse Subspace Clustering (ISSC), Maximum-Variance Principal Component Analysis (MVPCA), and Normalized Cut Optimal Clustering MVPCA (NC-OC-MVPCA), to investigate their feasibility at identifying discriminative bands such that classification performance is not drastically hindered. This would greatly benefit applications where time-sensitive solutions are needed to ensure optimal outcomes. In this research, an NVIDIA AGX Xavier module is used as the edge device to run trained models on as a simulated deployed unmanned aerial system. Performance of the proposed approach is measured in terms of classification accuracy and run time.
267

Savannah in the Ghost Light: Theater Design at the Urban Edge

Fall, Sarah 22 August 2022 (has links)
No description available.
268

Investigation of High-Pass Filtering for Edge Detection in Optical Scanning Holography

Zaman, Zayeem Habib 16 October 2023 (has links)
High-pass filtering has been shown to be a promising method for edge detection in optical scanning holography. By using a circular function as a pupil for the system, the radius of the circle can be varied to block out different ranges of frequencies. Implementing this system in simulation yields an interesting result, however. As the radius increases, a singular edge can split off into two edges instead. To understand the specific conditions under which this split occurs, Airy pattern filtering and single-sided filtering were implemented to analyze the results from the original high-pass simulation. These methods were tested with different input objects to assess any common patterns. Ultimately, no definitive answer was found, as Airy pattern filtering resulted in inconsistent results across different input objects, and single-sided filtering does not completely isolate the edge. Nonetheless, the documented results may aid a future understanding of this phenomenon. / Master of Science / Holograms are three-dimensional recordings of an object, reminiscent of how a photograph records a two-dimensional image of an object. Detecting edges in images and the reconstructed images from holograms can help us identify objects within the recorded image or hologram. In computer vision, common edge detection techniques involve analyzing the image's spatial frequency, or changes in relative intensity over space. One such technique is high-pass filtering, in which lower spatial frequencies are blocked out. High-pass filtering can also be applied to holographic imaging systems. However, when applying high-pass filtering to a holographic system, detected edges can split into two as higher frequencies are filtered out. This thesis examines the conditions for why this split-edge phenomenon occurs by modifying the original recorded object and the filtering mechanism, then analyzing the resultant holograms. While the results did not give a conclusive answer, they have been documented for the purpose of further research.
269

A Comparative Study on Service Migration for Mobile Edge Computing Based on Deep Learning

Park, Sung woon 15 June 2023 (has links)
Over the past few years, Deep Learning (DL), a promising technology leading the next generation of intelligent environments, has attracted significant attention and has been intensively utilized in various fields in the fourth industrial revolution era. The applications of Deep Learning in the area of Mobile Edge Computing (MEC) have achieved remarkable outcomes. Among several functionalities of MEC, the service migration frameworks have been proposed to overcome the shortcomings of the traditional methodologies in supporting high-mobility users with real-time responses. The service migration in MEC is a complex optimization problem that considers several dynamic environmental factors to make an optimal decision on whether, when, and where to migrate. In line with the trend, various service migration frameworks based on a variety of optimization algorithms have been proposed to overcome the limitations of the traditional methodologies. However, it is required to devise a more sophisticated and realistic model by solving the computational complexity and improving the inefficiency of existing frameworks. Therefore, an efficient service migration mechanism that is able to capture the environmental variables comprehensively is required. In this thesis, we propose an enhanced service migration model to address user proximity issues. We first introduce innovative service migration models for single-user and multi-user to overcome the users’ proximity issue while enforcing the service execution efficiency. Secondly, We formulate the service migration process as a complicated optimization problem and utilize Deep Reinforcement Learning (DRL) to estimate the optimal policy to minimize the migration cost, transaction cost, and consumed energy jointly. Lastly, we compare the proposed models with existing migration methodologies through analytical simulations from various aspects. The numerical results demonstrate that the proposed models can estimate the optimal policy despite the computational complexity caused by the dynamic environment and high-mobility users.
270

Server-side factor graph optimization for on-manifold pre-integration in IoT sensors

Gradén, Samuel January 2023 (has links)
State and specifically location estimation is a core concept in automation and is a well-researched field. One such estimation technique is Moving Horizon Estimation (MHE). In this thesis, the MHE variant single-shooting estimation will estimate the location and velocity of a moving object. The moving object is equipped with an  Inertial Measuring Unit (IMU)  measuring acceleration and angular velocity. This thesis will explore pre-integrating the IMU measurement on the device attached to the moving object and using them in another device running the MHE. The acceleration and angular velocity measurements are measured in the local frame of reference of the moving object, rotating the measurement to a global frame of reference requires a known rotation of the tracked object, finding this rotation is also a task in this thesis. This thesis found the presented theory ill-equipped to estimate the object's state without an angle measurement, this thesis assumed any such measurement is made from a magnetometer but the solution presented is not biased towards any other method of measuring angles. With the addition of an angel measurement, the estimation performs at a decimeter-level precision for location.

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