Potentially available natural gas combined cycle capacity : opportunities for substantial CO₂ emissions reductions

Thesis (S.M. in Engineering and Management)--Massachusetts Institute of Technology, Engineering Systems Division, 2010.Cataloged from PDF version of thesis.Includes bibliographical references.This thesis analyzes the potential for existing natural gas combined cycle (NGCC) power generation to displace coal generation thereby reducing emissions of CO₂ and criteria pollutants regulated under the Clean Air Act. It also examines the potential for unused NGCC capacity to eliminate transmission congestion while simultaneously reducing CO₂ and other criteria pollutant emissions. The average capacity factor of the entire natural gas fleet in year 2008 was 26%. The average capacity factor of NGCC units, a subset of the gas fleet, is 41%. NGCC units, however, are designed to operate at capacity factors as high as 85%. The delta of these two numbers has generated significant policy interest as a means for reducing C02 emissions through some type of environmental dispatch that would favor NGCC over coal generation without the need for additional capital investment. The maximum potential of natural gas power generation to displace inefficient coal generation was determined. This upper limit can provide regulators and policy makers with guideposts for further review. Various operational constraints including transmission limitations were then modeled to determine the extent to which these constraints limit fuel switching opportunities. An analysis was conducted to estimate the effects of fuel switching on transmission congestion. The conclusion of this analysis was that generation from potentially available NGCC capacity located in regions with high load centers can help alleviate the transmission congestion problem with minimal or zero capital investment for building new generation capacity. Next, an hourly dispatch model was developed that incorporates many of the complexities of the power system. This model dispatches generation from various power plants under two scenarios: a carbon unconstrained scenario (base case); and a carbon constrained scenario. Under the carbon constrained scenario, dispatch preference is give to NGCC generation over coal generation. Two regions were modeled: the Electric Reliability Council of Texas (ERCOT), which is primarily Texas; and the Florida Reliability Coordinating Council (FRCC), which is primarily Florida. Results from the two cases indicate that, without compromising system reliability: In the ERCOT region, displacing some coal generation with existing and available NGCC generation would lower CO₂ emissions by nearly 22%, SO2 by 70% and NOx by 49%, compared to the base case. * In the FRCC region, displacing some coal generation with existing and available NGCC generation would lower CO₂ emissions by nearly 10%, 502 by 38% and NOx by 25%, compared to the base case. The model results also indicate that for both ERCOT and FRCC, these emissions savings can be achieved with a 10% increase in electricity prices. This translates into a cost of emissions reductions of $20/ton of CO₂ in ERCOT and$40/ton of CO₂ in FRCC. This compares to the cost of emissions reductions from corn ethanol, which is about $750/ton of CO₂, as reported by Congressional Budget Office'. Finally, a comparison was made between the results of the hourly dispatch model and the ReEDS model, a more complex model developed by Department of Energy's (DOE) National Renewable Energy Laboratory (NREL).by Anil Rachakonda.S.M.in Engineering and Managemen

Disruption to control network function correlates with altered dynamic connectivity in the wider autism spectrum.

Autism is a common developmental condition with a wide, variable range of co-occurring neuropsychiatric symptoms. Contrasting with most extant studies, we explored whole-brain functional organization at multiple levels simultaneously in a large subject group reflecting autism's clinical diversity, and present the first network-based analysis of transient brain states, or dynamic connectivity, in autism. Disruption to inter-network and inter-system connectivity, rather than within individual networks, predominated. We identified coupling disruption in the anterior-posterior default mode axis, and among specific control networks specialized for task start cues and the maintenance of domain-independent task positive status, specifically between the right fronto-parietal and cingulo-opercular networks and default mode network subsystems. These appear to propagate downstream in autism, with significantly dampened subject oscillations between brain states, and dynamic connectivity configuration differences. Our account proposes specific motifs that may provide candidates for neuroimaging biomarkers within heterogeneous clinical populations in this diverse condition

E(FG)\u3csup\u3e2\u3c/sup\u3e: A NEW FIXED-GRID SHAPE OPTIMIZATION METHOD

We propose a shape optimization method over a fixed grid. Nodes at the intersection with the fixed grid lines track the domain’s boundary. These “floating” boundary nodes are the only ones that can move/appear/disappear in the optimization process. The element-free Galerkin (EFG) method, used for the analysis problem, provides a simple way to create these nodes. The fixed grid (FG) defines integration cells for EFG method. We project the physical domain onto the FG and numerical integration is performed over partially cut cells. The integration procedure converges quadratically. The performance of the method is shown with examples from shape optimization of thermal systems involving large shape changes between iterations. The method is applicable, without change, to shape optimization problems in elasticity, etc. and appears to eliminate non-differentiability of the objective noticed in finite element method (FEM)-based fictitious domain shape optimization methods. We give arguments to support this statement. A mathematical proof is needed

3D Localisation of Target using Elevation Angle Algorithm with the use of Ground Radars

A new novel method based on elevation angle algorithm (EAA) is proposed in this paper, to obtain 3D position of target using range and azimuth measurements of two ground 2D radars. The EAA estimates optimal target elevation angle wrt contributing radar by solving a non-linear optimisation problem using Levenberg-Marquardt method in geo-centric frame such as earth-centred-earth-fixed. The target position in geodetic frame (WGS84) is then obtained using slant range, azimuth and estimated elevation angle. The proposed method is evaluated using simulated but realistic radar data and accuracy of estimated position is found to be comparable with true position (error within acceptable limit). The method is also evaluated with real data from actual ground 2D radars and estimated target position is found to be comparable with reference navigation data (GPS) on-board of target. For each radar, corresponding Extended Kalman filter (EKF) is used to handle noisy, asynchronous measurements and to provide estimated range and azimuth at common reference time for altitude estimation using proposed EAA method. In case of real data, the estimated altitude is found to be comparable GPS altitude with error less than 5 % of true altitude. From the study, it is found that EAA is suitable to estimate target position using measurements from only two contributing asynchronous 2D radars in real-time as compared to some other techniques such triangulation and Trilateration where at-least three radars are required to get the position of target. This method can be useful to utilise network of vintage long range 2D radars to determine target position and to fill the gap wherever/whenever target is out of detection range of 3D radars. In addition, EAA method is compared with commonly used methodology such range only localisation and results are presented

Weight loss in nonalcoholic fatty liver disease patients in an ambulatory care setting is largely unsuccessful but correlates with frequency of clinic visits

Background and Aims: Nonalcoholic fatty liver disease (NALFD) is a leading cause of liver disease. Weight loss improves clinical features of NAFLD; however, maintenance of weight loss outside of investigational protocols is poor. The goals of this study were to characterize patterns and clinical predictors of long-term weight loss in ambulatory patients with NAFLD

Spatial scale changes the drivers of beta-diversity along land-use, environmental and geographic gradients

Understanding the patterns of spatial change in community composition (betadiversity), and the processes that structure biological communities are central themes in ecology. While the impacts of habitat change on beta-diversity are well-studied, most studies have been restricted to a single spatial scale. As a result, the effects of changing spatial scale on beta-diversity patterns across both natural and human-modified habitats are little known. My thesis targets the effect of spatial scale on tree and bird beta-diversity in the Asia-Pacific region across gradients of latitude, elevation and land-use change. The First Chapter uses tree data (> one billion stems and > 2500 species) from 15 long-term ForestGEO plots across the Asia-Pacific region to show how spatial scale changes the relationship between beta-diversity and latitude. At small spatial scales, beta-diversity decreased with increasing latitude; but at large spatial scales, beta-diversity did not change with increasing latitude. Different relationships across spatial scales were caused by differences in species richness, which influenced β-diversity values at small spatial scales, but not at large spatial scales. The Second Chapter uses bird data from Sri Lanka to show how horizontal (geographic) and vertical (elevation) distances can influence bird beta-diversity within three different land-use types (protected rainforests, reserve buffers and intensive agriculture). I show that bird beta-diversity within all land-use types were similar across horizontal distances. However, bird betadiversity within land-use types were not similar across vertical distances; protected rainforests had higher beta-diversity than the other two habitats. The Third Chapter uses bird data from the Western Ghats – Sri Lanka biodiversity hotspot to determine the drivers of bird community assembly at three different spatial scales. The geographic barrier (the Palk Strait) is the most important driver of bird beta-diversity at large spatial scale. Land-use and environment were equally important at intermediate scales and land-use was the most important driver at small scales. In conclusion, this thesis demonstrates the importance of sampling at multiple spatial scales to better understand natural and human-influenced betadiversity. In the First Chapter I showed that spatial scale changes the relationship between beta-diversity and latitude; and improving sampling representativeness avoids the species richness dependence of beta-diversity. In the Second Chapter I demonstrated the crucial importance of conserving rainforests across the full elevation range available. In the Third Chapter I showed that considering community assembly processes at multiple spatial scales while selecting sites for biological conservation holds great promise for preventing further species loss.Thesis (Ph.D.) -- University of Adelaide, School of Biological Sciences, 201

Effective Screening of Chemical Penetration Enhancers for Transdermal Drug Delivery

The potency of a CPE in enhancing the permeation of a drug is usually determined by quantifying the amount of drug permeated through skin in the presence of the CPE. Typically, these experiments are performed in Franz diffusion cells, and the amount of drug permeated is quantified by using rigorous analytical techniques, which are resource and labor intensive, cost prohibitive and have limited throughput. Further, there is no rational design in the criteria for selecting candidate CPEs for study and this trial-and-error method can be time consuming. Therefore, a need exists for a robust, quick alternate technique that can effectively pre-screen the CPEs for their potency. In this study, resistive properties of skin were used to determine the potency of the CPEs. A high throughput multi-well resistance chamber was designed and constructed in order to increase the throughput from the experiments. The multi-well resistance chambers were equipped to perform the experiments at conditions identical to permeation experiments and forty two potential CPEs were evaluated, which were generated by virtual design techniques. Histological studies were also performed to test the toxic effects of selected potent CPEs.School of Chemical Engineerin

Fuzzy logic integration into construction management planning

ENGLISH: A construction of an asset is challenging work associated with huge responsibilities. Project manager’s main challenges in construction are generally Time-Cost-Quality dependent. In addition to these factors, Project Managers or construction Manager have to deal with numerous uncertainties in the process of construction. Considering its diverse nature and activity performed in construction. Here major role playing factor in success of a project is efficient scheduling of the construction project. While scheduling a project, the factors which are considered are mostly tangible, such as resources, labor and capital. My main objective in this research is to reduce the duration of the activity involved in construction, while considering qualitative factors like site organization, Labor Skills and quality of equipment used and reveal the effect of these tangible factors on duration of the project. Since these factors are difficult to be measured using classical mathematic theories. We have opted Fuzzy Logic Theory as our base, which can measure mathematically with use of Fuzzy Logic Tool Box in MATLAB®. In order to implement the proposed technique, various membership functions need to be estimated using judgement and guidance of experts. One of the main advantage of the proposed technique is that it can be easily implemented in existing computer programs and thus having a possibility to schedule a project efficiently