Robust feature space separation for deep convolutional neural network training

This paper introduces two deep convolutional neural network training techniques that lead to more robust feature subspace separation in comparison to traditional training. Assume that dataset has M labels. The first method creates M deep convolutional neural networks called {DCNNi}M i=1 . Each of the networks DCNNi is composed of a convolutional neural network ( CNNi ) and a fully connected neural network ( FCNNi ). In training, a set of projection matrices are created and adaptively updated as representations for feature subspaces {S i}M i=1 . A rejection value is computed for each training based on its projections on feature subspaces. Each FCNNi acts as a binary classifier with a cost function whose main parameter is rejection values. A threshold value ti is determined for ith network DCNNi . A testing strategy utilizing {ti}M i=1 is also introduced. The second method creates a single DCNN and it computes a cost function whose parameters depend on subspace separations using the geodesic distance on the Grasmannian manifold of subspaces S i and the sum of all remaining subspaces {S j}M j=1,j≠i . The proposed methods are tested using multiple network topologies. It is shown that while the first method works better for smaller networks, the second method performs better for complex architectures

A New Approach to Improve the Success Ratio and Localization Duration of a Particle Filter Based Localization for Mobile Robots

Abstract In real world applications, it is important that mobile robots know their location to achieve goals correctly. The localization of the robot is difficult by using raw sensor data because of the noisy measurements from these sensors. To overcome this difficulty probabilistic localization algorithm approaches can be used. The Particle filter is one of the Bayesian-based methods. In this study, two new features incorporated into the particle filter approach. These features are: decreasing the size of sample space using compass data and a new sensor model. The proposed approach is applied in the localization problem of a mobile robot. Performance of the proposed algorithm is compared with the performance of traditional particle filter approach by changing several parameters of the system. These analyses emphasized that the proposed approach improved the localization performance of the system. The results are promising for the future studies on this subject

KINETIC ANALYSIS OF METHANE HYDRATE FORMATION WITH BUTTERFLY TURBINE IMPELLERS

Heat generation during gas hydrate formation is an important problem because it reduces the amount of water and gas that become gas hydrates. In this research work, we present a new design of an impeller to be used for hydrate formation and to overcome this concern by following the hydrodynamic literature. CH4 hydrate formation experiments were performed in a 5.7 L continuously stirred tank reactor using a butterfly turbine (BT) impeller with no baffle (NB), full baffle (FB), half baffle (HB), and surface baffle (SB) under mixed flow conditions. Four experiments were conducted separately using single and dual impellers. In addition to the estimated induction time, the rate of hydrate formation, hydrate productivity and hydrate formation rate, constant for a maximum of 3 h, were calculated. The induction time was less for both single and dual-impeller experiments that used full baffle for less than 3 min and more than 1 h for all other experiments. In an experiment with a single impeller, a surface baffle yielded higher hydrate growth with a value of 42 108 mol/s, while in an experiment with dual impellers, a half baffle generated higher hydrate growth with a value of 28.8 108 mol/s. Both single and dual impellers achieved the highest values for the hydrate formation rates that were constant in the full-baffle experiments

Gas hydrate technology: state of the art and future possibilities for Europe

Interest in natural gas hydrates has been steadily increasing over the last few decades, with the understanding that exploitation of this abundant unconventional source may help meet the ever-increasing energy demand and assist in reduction of CO2 emission (by replacing coal). Unfortunately, conventional technologies for oil and gas exploitation are not fully appropriate for the specific exploitation of gas hydrate. Consequently, the technology chain, from exploration through production to monitoring, needs to be further developed and adapted to the specific properties and conditions associated with gas hydrates, in order to allow for a commercially and environmentally sound extraction of gas from gas hydrate deposits. Various academic groups and companies within the European region have been heavily involved in theoretical and applied research of gas hydrate for more than a decade. To demonstrate this, Fig. 1.1 shows a selection of leading European institutes that are actively involved in gas hydrate research. A significant number of these institutes have been strongly involved in recent worldwide exploitation of gas hydrate, which are shown in Fig. 1.2 and summarized in Table 1.1. Despite the state of knowledge, no field trials have been carried out so far in European waters. MIGRATE (COST action ES1405) aims to pool together expertise of a large number of European research groups and industrial players to advance gas-hydrate related activity with the ultimate goal of preparing the setting for a field production test in European waters. This MIGRATE report presents an overview of current technologies related to gas hydrate exploration (Chapter 2), production (Chapter 3) and monitoring (Chapter 4), with an emphasis on European activity. This requires covering various activities within different disciplines, all of which contribute to the technology development needed for future cost-effective gas production. The report points out future research and work areas (Chapter 5) that would bridge existing knowledge gaps, through multinational collaboration and interdisciplinary approaches

Evaluation of Geothermal District Heating Systems of Turkey

Turkey is one of the few countries that has almost all possible applications of geothermal energy. Geothermal district heating has a relatively short history (since 1987) compared to other direct utilization but plays important economic, social and environmental roles in some towns. There are 18 geothermal district heating systems (GDHS), mainly in the Aegean region with resource temperatures between 57–145C. Current heating capacities of those systems are in the range of 570 to 37500 Residence Equivalent (RE, 1 RE= 100 m2 heated area). This paper evaluates each GDHS on their technical characteristics, then gives details about three GDHS and compares the economics of district heating applications based on alternative fuel prices

Flow Testing of Balcova Geothermal Field Turkey

Balçova geothermal field is located in a densely populated area which makes direct heat applications very efficient and economical. Heat produced from Balçova geothermal field is utilized for three main purposes: greenhouse heating, balneology and residential heating. Among these three applications, the latter one is the main application throughout the Balçova District Heating System. The field produces hot water from two different horizons: one shallow and one deeper zone. After had utilized for 16 years, few wellbores in the deeper zone had to be abandoned because of operational difficulties, and new wellbores were drilled in the same zone. Interference tests were carried out during flow testing at newly drilled wellbores. Analysis of pressure response at observation wellbores for production/injection practices indicated that there exists a very strong connection within the wellbores in the same zone. In addition, there exists also a hydraulic but weaker connection between shallower and deeper zones. Response of the field and the operational changes in production/injection applications are also presented

Natural gas hydrates as a cause of underwater landslides: A review

Natural gas hydrates occur worldwide in polar regions, normally associated with onshore and offshore permafrost, and in sediment of outer continental margins. The total amount of methane in gas hydrates likely doubles the recoverable and non-recoverable fossil fuels. Three aspects of gas hydrates are important: their fossil fuel resource potential, their role as a submarine geohazard, and their effects on global climate change. Since gas hydrates represent huge amounts of methane within 2000 m of the Earth's surface, they are considered to be an unconventional, unproven source of fossil fuel. Because gas hydrates are metastable, changes of pressure and temperature affect their stability. Destabilized gas hydrates beneath the seafloor lead to geologic hazards such as submarine slumps and slides. Destabilized gas hydrates may also affect climate through the release of methane, a "greenhouse" gas, which may enhance global warming

Effect of carbon dioxide on PVT behavior of geothermal fluids and prevention of calcite deposition by inhibitor injection

Ph.D. - Doctoral Progra