Evaluation of flow and scalar transport characteristics of small public drinking water disinfection systems using computational fluid dynamics

2011 Spring.Includes bibliographical references.This study focuses on the evaluation of flow and scalar transport characteristics of small disinfection systems, primarily through computational fluid dynamics (CFD) as well as physical conservative tracer studies. Original research was performed on a pipe loop, series of pressurized tanks, and two separate open surface tank contact systems and a case study was performed on a baffled tank system. The flow dynamics for each of these respective disinfection systems were evaluated using CFD. The flow dynamics govern the transport of any quantity (e.g., a passive scalar, conservative tracer, or chlorine-containing species) through the system visualized through plotting the effluent concentration (e.g., passive scalar for computational models and conservative tracer for physical experiments) through time forming what is commonly referred to as a residence time distribution (RTD), or flow-through, curve. Physical experiments provided validation for the CFD models that give a more complete view of hydraulic efficiency thus overcoming the common "black-box" approach to contact tank design using only the theoretical detention time (TDT) (defined as the system volume V divided by the volumetric flow rate Q). The differing geometries of contact tank systems yield significantly different flow paths with varying degrees of separation, recirculation, inlet and outlet effects, and wall effects prompting the need for the evaluation of hydraulic efficiency to be unique to the system. Yet current practice evaluates the hydraulic efficiency of disinfection contact tank systems based on the TDT and the rising limb of the RTD curve, designated by the United States Environmental Protection Agency (USEPA) as baffle factor (BF). Research presented in this study using CFD models and physical tracer studies shows that evaluation methods based upon TDT tend to overestimate, severely in some instances, the actual hydraulic efficiency as obtained from the systems' flow and scalar transport dynamics and subsequent RTD curves. The main objectives of this study were to determine the systems' respective hydraulic efficiencies and to analyze an alternative measure of hydraulic efficiency, the ratio t10/t90, where t10 and t90 are the time taken for 10 and 90 percent of the input concentration to be observed at the outlet of a system. The pipe loop system was dominated by advection and thus showed little variance in the values of BF and t10/t90. Analysis of the series of pressurized tank systems showed significant regions of turbulent mixing and recirculation corresponding to a system that was much less efficient than the pipe loop system. BF values for the pressurized tank systems were nearly 100 percent greater than t10/t90 values as a result of a system behavior further from plug flow. The open surface tank systems exhibited the most uneven flow paths and lowest efficiencies seen in this study with BF and t10/t90 values differing by at least 100 percent. These systems exhibited significant degrees of short-circuiting and recirculation largely due to their inlet and outlet configurations. Finally, the baffled tank system showed an increase in system efficiency with the number of baffles (e.g., increase in advective forces) and a corresponding decrease in the variance between BF and t10/t90 values. Overall, the research presented in this thesis provides an extensive evaluation for the flow and scalar characteristics of the described small public drinking water disinfection systems allowing for the development of t10/t90 as a more representative evaluation of hydraulic efficiency

Evaluation and parameterization of stably stratified turbulence: insights on the atmospheric boundary layer and implications for wind energy, An

2014 Fall.Includes bibliographical references.This research focuses on the dynamics of turbulent mixing under stably stratified flow conditions. Velocity fluctuations and instabilities are suppressed by buoyancy forces limiting mixing as stability increases and turbulence decreases until the flow relaminarizes. Theories that ubiquitously assume turbulence collapse above a critical value of the gradient Richardson number (e.g. Ri > Ric) are common in meteorological and oceanographic communities. However, most theories were developed from results of small-scale laboratory and numerical experiments with energetic levels several orders of magnitude less than geophysical flows. Geophysical flows exhibit strong turbulence that enhances the transport of momentum and scalars. The mixing length for the turbulent momentum field, LM, serves as a key parameter in assessing large-scale, energy-containing motions. For a stably stratified turbulent shear flow, the shear production of turbulent kinetic energy, P, is here considered to be of greater relevance than the dissipation rate of turbulent kinetic energy, ε. Thus, the turbulent Reynolds number can be recast as Re ≡ k2/(ν P) where k is the turbulent kinetic energy, allowing for a new perspective on flow energetics. Using an ensemble data set of high quality direct numerical simulation (DNS) results, large-eddy simulation (LES) results, laboratory experiments, and observational field data of the stable atmospheric boundary layer (SABL), the dichotomy of data becomes apparent. High mixing rates persist to strong stability (e.g. Ri ≈ 10) in the SABL whereas numerical and laboratory results confirm turbulence collapse for Ri ~ O(1). While this behavior has been alluded to in literature, this direct comparison of data elucidates the disparity in universal theories of stably stratified turbulence. From this theoretical perspective, a Reynolds-averaged framework is employed to develop and evaluate parameterizations of turbulent mixing based on the competing forces of mean shear and buoyancy frequency, S and N, respectively. Length scale estimates for LM are given by LkS ≡ k1/2/S and LkN ≡ k1/2/N, where LkS provides an accurate estimate for eddy viscosity, νt, under neutral to strongly stable conditions for SABL data. The relative influence of shear and buoyancy are given by the ratio of the respective time scales, S-1 and N-1, with the pertinent time scale of the large-scale motions, TP ≡ k/P, through the parameters STP and NTP. LkS's range of applicability is further assessed in a STP-NTP parameter space. In developing these parameterizations, the stress-intensity ratio, c2, is evaluated using high-Re stably stratified data and is shown to exhibit a near constant value (c2 ≈ 0.25) for stably stratified geophysical turbulence. These findings provide a clear trajectory for numerical modeling of stably stratified geophysical shear turbulence without reliance on stability or damping functions, tuning parameters, or artificial parameterizations. An initial modeling study of moderate-Re channel and Ekman layer flows using the proposed parameterizations confirms this supposition. Finally, it is in this new light that large-scale implications of wind energy can now be considered. As a first step in this process, computational fluid dynamics (CFD) studies of wind turbine interactions are carried out under neutrally stratified conditions. Simulations clearly show that actuator line models provide efficacy in wake generation, interaction, and restoration and highlight model requirements for stably stratified conditions. Results suggest that standard horizontal spacings of 5-10 rotor diameters yield significant reductions in power output and increases turbulence intensity and fatigue loading

The association between hysterectomy and ovarian cancer risk: A population-based record-linkage study

Background: Recent studies have called into question the long-held belief that hysterectomy without oophorectomy protects against ovarian cancer. This population-based longitudinal record-linkage study aimed to explore this relationship, overall and by age at hysterectomy, time period, surgery type, and indication for hysterectomy. Methods: We followed the female adult Western Australian population (837 942 women) across a 27-year period using linked electoral, hospital, births, deaths, and cancer records. Surgery dates were determined from hospital records, and ovarian cancer diagnoses (n¼1640) were ascertained from cancer registry records.We used Cox regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between hysterectomy and ovarian cancer incidence. Results: Hysterectomy without oophorectomy (n¼78 594) was not associated with risk of invasive ovarian cancer overall (HR ¼ 0.98, 95% CI ¼ 0.85 to 1.11) or with the most common serous subtype (HR ¼ 1.05, 95% CI ¼ 0.89 to 1.23). Estimates did not vary statistically significantly by age at procedure, time period, or surgical approach. However, among women with endometriosis (5.8%) or with fibroids (5.7%), hysterectomy was associated with substantially decreased ovarian cancer risk overall (HR ¼ 0.17, 95% CI ¼ 0.12 to 0.24, and HR ¼ 0.27, 95% CI ¼ 0.20 to 0.36, respectively) and across all subtypes. Conclusions: Our results suggest that for most women, having a hysterectomy with ovarian conservation is not likely to substantially alter their risk of developing ovarian cancer. However, our results, if confirmed, suggest that ovarian cancer risk reduction could be considered as a possible benefit of hysterectomy when making decisions about surgical management of endometriosis or fibroids

Serum N-propeptide of collagen IIA (PIIANP) as a marker of radiographic osteoarthritis burden

Cartilage homeostasis relies on a balance of catabolism and anabolism of cartilage matrix. Our goal was to evaluate the burden of radiographic osteoarthritis and serum levels of type IIA procollagen amino terminal propeptide (sPIIANP), a biomarker representing type II collagen synthesis, in osteoarthritis

A Systems Approach and Notional Response Model for Preserving the Health System during the COVID-19 Pandemic

During any pandemic, it has long been known that local jurisdictions would need to be self-sufficient with little or no outside assistance, particularly from the federal government. While all eyes have been on California, New York, and Massachusetts, the capacities of health systems in other states have yet to be put to the test. If there are subsequent waves of COVID-19 and other jurisdictions see significant increases in disease spread, the systems used to respond will become critical.Using a review and synthesis approach, this article explores our collective experience and knowledge as it pertains to use of alternate care sites for dealing with the patient surge created by a disease outbreak. Probing the concept of alternate care site (ACS) systems reveals various types of alternate care sites that may be employed during an outbreak. The historical value of ACS models used during outbreak response are discussed. This culminates in the development of a notional response model and list of actions that should be taken by all jurisdictions as we prepare for additional waves of disease

Political participation: the vocational motivations of Labour party employees

Party employees are an under-researched group in political science. This article begins to address this oversight by examining Labour Party employees using new quantitative and qualitative data. It argues that party employment should be regarded as a form of political participation and as a consequence, existing models of political participation can be utilised to help explain why people work for political parties. After testing these propositions, the article concludes that existing models are indeed helpful in explaining the motivations for party employment

Comparative absorption of curcumin formulations

BACKGROUND: The potential health benefits of curcumin are limited by its poor solubility, low absorption from the gut, rapid metabolism and rapid systemic elimination. The purpose of this study was the comparative measurement of the increases in levels of curcuminoids (curcumin, demethoxycurcumin, bisdemethoxycurcumin) and the metabolite tetrahydrocurcumin after oral administration of three different curcumin formulations in comparison to unformulated standard. METHODS: The relative absorption of a curcumin phytosome formulation (CP), a formulation with volatile oils of turmeric rhizome (CTR) and a formulation of curcumin with a combination of hydrophilic carrier, cellulosic derivatives and natural antioxidants (CHC) in comparison to a standardized curcumin mixture (CS) was investigated in a randomized, double-blind, crossover human study in healthy volunteers. Samples were analyzed by HPLC-MS/MS. RESULTS: Total curcuminoids appearance in the blood was 1.3-fold higher for CTR and 7.9-fold higher for CP in comparison to unformulated CS. CHC showed a 45.9-fold higher absorption over CS and significantly improved absorption over CP (5.8-fold) and CTR (34.9-fold, all p < 0.001). CONCLUSION: A formulation of curcumin with a combination of hydrophilic carrier, cellulosic derivatives and natural antioxidants significantly increases curcuminoid appearance in the blood in comparison to unformulated standard curcumin CS, CTR and CP

Prospectus, October 9, 2002

https://spark.parkland.edu/prospectus_2002/1025/thumbnail.jp

Mars Surface Mobility: Comparison of Past, Present, and Future Rover Systems

The future robotic and human exploration of Mars will rely heavily on mobile system to meet exploration objectives. In particular, the next decade of exploration (2009-2020) will utilize rovers and other mobile surface platforms to conduct a wide variety of tasks, including in the search for water and life, characterization of terrain and its geology, and conduct precursor measurements prepare for future human exploration