Effects of Secondary Air Injection Upon the Fluidization Characteristics of the Lower Stage in a Two-Stage, Variable-Area Fluidized Bed Riser

A transparent scale model of a two-stage fluidized bed coal dryer with a small diameter lower stage and a large diameter upper stage, separated by a conical transition zone with secondary air injection ports, has been constructed to study the effects of secondary air injection upon the fluidization characteristics of the lower riser stage. The superficial velocity of the lower stage of the riser was held constant within the turbulent fluidization regime while the superficial gas velocity in the upper riser stage was varied by changing the volumetric flow rates of air introduced between the upper and lower riser stages. Through examination of time series pressure data via standard deviation, autocorrelation, spectral density plots and visual observation of dense bed height, it becomes apparent that secondary air injection has a dominant effect upon the fluidization characteristics below the injection location, leading to a transition from a dense to a dilute bed

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This final design report will detail the entire engineering design process from conceptualization through manufacturing and testing. After introducing the topic and scope of the project this document presents all of the benchmarking and research performed in order to obtain as much information about similar current products and possible solutions. Next the objectives of the project are presented where the needs are transformed into engineering specifications that will guide the design of the product. Design developed is then presented with ideation, idea evaluation and selection, analysis, manufacturing considerations, and final design selection. The final design is then presented with each of its three subsystems, including supporting analysis, manufacturing and testing plans, bill of materials and cost as well as material selection, safety considerations, and maintenance plans. Following that is the management plan where team roles are outlines and project deadlines are presented. Product realization is next, which includes the manufacturing process that was taken for all components as well as description of changes between the planned and built design and recommendations for future manufacturing changes. Design verification follows with testing procedures and results and a final budget for the manufactured design. Next are conclusions that summarize what was done during the project and recommendations which outline what could have been done differently from a design or project standpoint to provide insight for future designs. References for all researched information are included in order cited throughout the document. Finally all appendices are included at the end of the document that were referenced throughout the report as well as other important information

A Search for Exozodiacal Clouds with Kepler

Planets embedded within dust disks may drive the formation of large scale clumpy dust structures by trapping dust into resonant orbits. Detection and subsequent modeling of the dust structures would help constrain the mass and orbit of the planet and the disk architecture, give clues to the history of the planetary system, and provide a statistical estimate of disk asymmetry for future exoEarth-imaging missions. Here we present the first search for these resonant structures in the inner regions of planetary systems by analyzing the light curves of hot Jupiter planetary candidates identified by the Kepler mission. We detect only one candidate disk structure associated with KOI 838.01 at the 3-sigma confidence level, but subsequent radial velocity measurements reveal that KOI 838.01 is a grazing eclipsing binary and the candidate disk structure is a false positive. Using our null result, we place an upper limit on the frequency of dense exozodi structures created by hot Jupiters. We find that at the 90% confidence level, less than 21% of Kepler hot Jupiters create resonant dust clumps that lead and trail the planet by ~90 degrees with optical depths >~5*10^-6, which corresponds to the resonant structure expected for a lone hot Jupiter perturbing a dynamically cold dust disk 50 times as dense as the zodiacal cloud.Comment: 22 pages, 6 figures, Accepted for publication in Ap

Nitrogen availability and forest productivity along a climosequence on Whiteface Mountain, New York

We studied broadleaf and needle-leaf forests along an elevation gradient (600–1200 m) at Whiteface Mountain, New York, to determine relationships among temperature, mineral N availability, and aboveground net primary productivity (ANPP) and controls on the latter two variables. We measured net N mineralization during the growing season, annual litterfall quantity and quality, aboveground woody biomass accumulation, and soil organic matter quality. Inorganic N deposition from cloudwater markedly increases mineral N availability above 1000 m in this region. Consequently, mineral N availability across the climosequence remains relatively constant because N mineralization decreases with increasing elevation. Across this climosequence, air temperature (as growing season degree-days) exerted the most control on ANPP. Nitrogen mineralization was most strongly related to soil growing season degree-days and less so to lignin to N ratios in litter. ANPP was correlated with N mineralization but not with mineral N availability. Combining our data with those from similar studies in other boreal and cool temperate forests shows that N mineralization and ANPP are correlated at local, regional, and interbiome scales. Regarding the persistent question concerning cause and effect in the N mineralization – forest productivity relationship, our data provide evidence that at least in this case, forest productivity is a control on N mineralization

Timescales of spike-train correlation for neural oscillators with common drive

We examine the effect of the phase-resetting curve (PRC) on the transfer of correlated input signals into correlated output spikes in a class of neural models receiving noisy, super-threshold stimulation. We use linear response theory to approximate the spike correlation coefficient in terms of moments of the associated exit time problem, and contrast the results for Type I vs. Type II models and across the different timescales over which spike correlations can be assessed. We find that, on long timescales, Type I oscillators transfer correlations much more efficiently than Type II oscillators. On short timescales this trend reverses, with the relative efficiency switching at a timescale that depends on the mean and standard deviation of input currents. This switch occurs over timescales that could be exploited by downstream circuits