Electricity produced and delivered to customers constitutes one of the largest consumer markets in the world. As a nation we have become so dependent that most daily functions would be suspended if there were any interruption in power generation, transmission and distribution. Historically there has been a great deal of effort put into modeling and improving the reliability of the generation and transmission systems. However, when compared to the generation and transmission systems, considerable less resources has been placed on the details of making the distribution system more reliable. Majority of all interruptions experienced by the customer in a given year are due to the distribution system. In addition, since the penetration of distributed generation is projected to increase to at least 20% of peak load by 2020, the inclusion of distributed generation in distribution system reliability assessment is highly desired. This research seeks to model the impact of distributed generation to distribution system reliability. Since utility-connected distributed generation is typically installed close to the consumers, it can reduce the current at the main feeder. Consequently, it increases the chance that a stressed feeder can be reconfigured under a fault at a neighboring feeder. As a comparison, it may be impossible to reconfigure feeder connection because reconfiguration will lead to line overflow without distributed generators to supply part of the load. The reliability assessment in this work is carried out with analytical approach and sequential Monte Carlo simulation. The analytical approach presents the reliability measures like SAIFI and SAIDI during the course of an average year. Hence, the mean values of SAIFI and SAIDI for distribution systems with or without distributed generation are obtained. However, sequential Monte Carlo simulation can give the probabilistic distribution of SAIFI and SAIDI based on a large sample of random failures of system components. Test results from a system modified from the IEEE 34-bus system will be presented based on the analytical approach and the Monte Carlo simulation. It is shown that installation of distributed generators can improve the distribution system reliability considerably

OBJECTIVE: The objective of this experimental investigation was to document the turbulent mixing of subsonic axisymmetric hydrogen and air streams at velocity ratios which have not been previously reported. Special emphasis is placed on [1] determining the effect of velocity ratio and density gradients on the centerline decay of composition, velocity, and total enthalpy, and on the composition, velocity, and total enthalpy profile shapes, and [2] presenting nondimensional composition, velocity, and total enthalpy relationships which are indicative of the turbulent Prandtl, Lewis, and Schmidt numbers.

Land disturbances cause considerable environmental, economic, and health impacts from the detachment, transport, and deposition of sediment. The Revised Universal Soil Loss Equation-version 2 (RUSLE2) is an erosion and sediment transport model commonly used by regulatory agencies to develop management strategies that mitigate some of these impacts. RUSLE2 uses the eroded sediment size distribution (ESSD) at the point of detachment in mass transport calculations, which are generally assumed to obey particle diameter/fall velocity relationships consistent with Stokes Law. RUSLE2 currently estimates the distribution of eroded sediment by dividing the ESSD at the point of detachment into 5 size classes solely as a function of the matrix soil dispersed clay content. The present model fails to describe the impacts of some popular sustainable agriculture systems because specific effects of soil management practices (tillage and residue), as they influence the ESSD, were not accounted for when the equations were developed. Additionally, the current relationships only describe ESSDs at the point of detachment, which fails to describe spatially related ESSD differences. Finally, the number of size classes currently used to describe the ESSD does not adequately represent true conditions. This study revised current ESSD equations through an analysis of published research not accounted for in the current RUSLE2 model, with emphasis on the effects of management and scale. The research found that the proposed revisions to these equations better describe the size distribution of hillslope detached particles for four independent data sets (avg. RMSE = 182.5 micrometer) than the current approach (RMSE = 208.4 micrometer), partially by including previously unaccounted management factors. Spatial relationships as they influence the ESSD were also defined to aid RUSLE2 in modeling difference and correlations between the resulting sheet and rill ESSD as either scale predominates. The resulting RUSLE2 modifications were found to be more accurate and describe a broader range of conditions, so these equations could ultimately be implemented in conjunction with a RUSLE-based field scale model to aid in managing chemical transport as well as sediment yield.

Sodium cobaltate possesses all the important traits needed in a material for potential thermoelectric applications yet it shows little regard for the traditional physics of thermoelectrics. As existing theories regarding the phenomenon in NaxCoO2 are incomplete, we have set out to elucidate some of the issues by looking into the elastic response of the system. To this effect, we have employed Resonant Ultrasound Spectroscopy to obtain the elastic tensor at various temperatures. As the Na0.75CoO2 stoichiometry seemed to potentially offer the most rewards due to a pronounced ground state and anomalous thermopower at higher temperatures, this composition was chosen for study. Polycrystal samples and floating zone grown single crystal samples were studied in temperatures ranging from 5K to 300K and in various magnetic fields from 0T to 5T. Elastic tensors were obtained for various samples whereas the absolute values of the moduli show insufficient agreement to be conclusive. The temperature dependence however is very consistent and displays two regions of interest (30K-60K temperature range and 250K- 300K range). In both regions, the material appears to stiffen with increasing temperature before relaxing back to its lower initial state. Anomalous activities at these temperatures have not been observed by most existing studies, thus have not been the subject of much discussion to date. As neither our data nor that of thermal conductivity measurements has displayed any signs of the 22K low temperature transition observed by magnetic and electronic transport measurements, it is our belief that the transition into the low temperature ground state is characterized by a rather weak coupling between phonons and the charge carriers that drive the transition. The natures of the high and low temperature anomalies are currently unclear.

Selective catalytic reduction (SCR) of NOx with urea/NH3 is a leading candidate to the impending more stringent emissions regulations for diesel engines. Currently, there is no consensus on the durability and the deactivation mechanisms associated with zeolite-based SCR catalysts, nor is there an established protocol for rapidly aging zeolite-based SCR catalysts that replicates the catalyst deactivation associated with field service. A 517 cc single-cylinder, naturally-aspirated direct injection (NA/DI) diesel engine is used to perform accelerated thermal aging on Fe-zeolite SCR catalysts. The engine is fitted with an exhaust aftertreatment system consisting of a DOC, a SCR catalyst and a DPF. Accelerated aging protocol established for the SCR catalyst utilizes high temperature exhaust gases during the active regeneration of the DPF. Accelerated aging is carried out at exhaust gas temperatures of 650, 750 and 850°C at the SCR inlet and at a gas hourly space velocity (GHSV) of approximately 40,000 h-1. The engine is maintained at 1500 rpm and supplemental fuel is injected upstream of the DOC to alter the temperature of the aftertreatment system. The aged Fe-zeolite SCR catalysts are evaluated for NOx performance in a bench-flow reactor and characterized by multiple surface characterization techniques for materials changes. The NOx performance of the front sections of the engine-aged catalysts is severely degraded. BET surface area measurements of the engine-aged catalyst indicate a severe reduction of catalyst surface area in the front sections of the catalysts aged at 750 and 850°C. However, the catalyst aged at 650°C has a catalyst surface area similar to that of a fresh catalyst; thereby ruling out reduction of catalyst surface area as the sole cause of the catalyst deactivation seen in the front sections of the engine-aged catalysts. The similar shape of the NOx conversion profiles observed with these catalyst sections even at different aging temperatures indicates some type of catalyst poisoning; however, the cause of catalyst degradation in these catalyst sections is not identified in this investigation. There is a good relationship between the NOx performance and catalyst aging temperature for the rear sections of the engine-aged catalysts – NOx performance decreases with increasing aging temperature. XRD patterns and NO oxidation experiments reveal evidence of zeolite dealumination in the engine-aged catalysts. BET surface area measurements show that catalyst surface area decreases with increasing aging temperature, which further supports the suggestion of zeolite dealumination as the cause of catalyst deactivation in the rear sections of the engine-aged catalysts. A comparison between the engine-aged and field-aged catalysts is conducted to assess the validity of the implemented accelerated thermal aging protocol in replicating the aging conditions observed in the field-aged catalyst. Bench-flow reactor evaluation is used to determine the NOx performance of the engine-aged and field-aged catalysts, and in depth surface studies are used to determine the deactivation mechanisms associated with each type of catalyst aging. SEM micrographs and BET surface area measurements of the aged catalysts show that the deactivation mechanism associated with catalyst aging is primarily physical damage to the zeolite washcoat for both the field-aged and engine-aged catalysts. Furthermore, X-ray diffraction and NO oxidation experiments identify zeolite dealumination as the underlying cause of the washcoat degradation. Finally, BFR evaluation shows that the NOx performance of the catalyst aged at 750°C for approximately 50 hours compares very well to that of the field-aged catalyst with a service life of 3 years. It is concluded that accelerated thermal aging on the engine bench is successful in bringing about similar catalyst changes to those seen with the field-aged catalyst.

The objective of the present study was to laser process a refractory metal – refractory carbide alloy based on W-Ti-C ternary system for severe service applications. The key concept was to cast a eutectic alloy of tungsten and titanium carbide/carbonitride straight from the melt through laser materials processing route. In the present study, a WTi- C ternary alloy has been laser processed into three-dimensional objects and surface protective coatings. Two novel fabrication systems were designed to build threedimensional objects, namely tower nozzle solid freeform fabrication system and axissymmetric laser powder deposition system. W-Ti-C alloy based protective coatings were deposited on graphite substrates, through laser melting of pre-placed powder mixture, to widen the use of carbon structural elements for high temperature applications. A method for depositing W-Ti-C alloy on steel using multi-intermediate layers strategy is discussed and the preliminary results are presented in this study.

Years of study and constant anecdotal infonnation dating back to the ancient Romans exists regarding the relationship of mandibular position, occlusion surface changes, and human performance. Such old sayings and practices like "bite the bullet" and the actual act ofclenching one's teeth on a stick prior to exertion or in anticipation ofpain are but two examples of how this relationship has been intuitively understood by man for some time. Previous scientific works in this area have generally suffered at least one serious shortcoming in data collection, data analysis, test device flaws or lack of control measures. There seem to be emotionally charged efforts to either prove or disprove the apparent relationship between jaw positioning and human performance. It is unclear why there has been so much controversy but the fact that this emotional side taking exists leads to concerns about preconceptions on the part ofthe previous research teams. In an effort to reach some realistic levels of confidence, this effort has been accomplished in a double blind, placebo controlled, unbiased manner utilizing the tenets of the scientific method throughout. The data indicate that a self-fit, intra-oral device is beneficial in improving grip strength values for both men and women at a confidence level of at least 95 percent. In addition, there is a 96 percent confidence level that a mandibular repositioning appliance is of greater assistance in grip strength tests than a placebo device. Therefore, the results of this research initiative demonstrate that statistically relevant human performance increases are possible by employing a self-fit, intra-oral device in active men and women ofall ages.

Quartz particulate composites

Monitoring & maintenance management

Particulate metal matrix composites