http://idea.library.drexel.edu/handle/1860/729 http://idea.library.drexel.edu/retrieve/4828 http://idea.library.drexel.edu/handle/1860/729 Search the Channel search http://idea.library.drexel.edu/simple-search http://idea.library.drexel.edu/handle/1860/2687 Title: A quantitative microbial risk assessment model for Legionnaires' disease: animal model selection and dose-response modeling <br/> <br/>Authors: Armstrong, T.W.; Haas, Charles Nathan <br/> <br/>Abstract: Legionnaires’ Disease (LD), first reported in 1976, is an atypical pneumonia caused by bacteria of the genus Legionella, and most frequently by L. pneumophila (Lp). Subsequent research on exposure to the organism employed various animal models, and with Quantitative Microbial Risk Assessment techniques, the animal model data may provide insights on human dose-response for LD. The present report focuses on the rationale for selection of the guinea pig model, comparison of the dose-response model results, comparison of projected low-dose responses for guinea pigs, and risk estimates for humans. Based on both in vivo and in vitro comparisons, the guinea pig (Cavia porcellus) dose-response data were selected for modeling human risk. We completed dose-response modeling for the β-Poisson (approximate and exact), exponential, probit, logistic and Weibull models for Lp inhalation mortality and infection (end point elevated body temperature) in guinea pigs. For mechanistic reasons, including low-dose exposure probability, further work on human risk estimates for LD employed the exponential and β-Poisson models. With an exposure of 10 Colony Forming Units (retained dose), the QMRA model predicted a mild infection risk of 0.4 (as evaluated by seroprevalence) and a clinical severity LD case (e.g., hospitalization and supportive care) risk of 0.0009. The calculated rates based on estimated human exposures for outbreaks used for the QMRA model validation are within an order of magnitude of the reported LD rates. These validation results suggest the LD QMRA animal model selection, dose-response modeling, and extension to human risk projections were appropriate. http://idea.library.drexel.edu/handle/1860/2683 Title: Using a global positioning system to measure tidal currents in Absecon Inlet, Atlantic City, NJ <br/> <br/>Authors: Weggel, J. Richard; Walz, James K.; Lomax, Joseph; Sray, Mark <br/> <br/>Abstract: As a permit requirement for the development of a marina within Absecon Inlet, Atlantic City, NJ, tidal current measurements were required. Maximum ebb and flood currents determine the forces to which the structural elements of the marina will be subjected as well as sediment transport patterns near the marina. Currents also influence the maneuverability of small craft attempting to enter or exit the marina. Consequently, current velocities and directions during maximum ebb and flood tides (spring tides) were measured on 10 March 2005 in the vicinity of the proposed marina using the Global Positioning System (GPS). The location of the proposed marina in the inlet is shown in Figure 1. Current patterns are affected by the presence of Clam Creek (on southwest side of the study area) and the Route 87 Bridge over the inlet. The marina site is also subject to locally generated wind waves as well as waves entering the inlet from the Atlantic Ocean. http://idea.library.drexel.edu/handle/1860/2641 Title: Application of zonal model on indoor air sensor network design <br/> <br/>Authors: Chen, Y. Lisa; Wen, Jin <br/> <br/>Abstract: Growing concerns over the safety of the indoor environment have made the use of sensors ubiquitous. Sensors that detect chemical and biological warfare agents can offer early warning of dangerous contaminants. However, current sensor system design is more informed by intuition and experience rather by systematic design. To develop a sensor system design methodology, a proper indoor airflow modeling approach is needed. Various indoor airflow modeling techniques, from complicated computational fluid dynamics approaches to simplified multi-zone approaches, exist in the literature. In this study, the effects of two airflow modeling techniques, multi-zone modeling technique and zonal modeling technique, on indoor air protection sensor system design are discussed. Common building attack scenarios, using a typical CBW agent, are simulated. Both multi-zone and zonal models are used to predict airflows and contaminant dispersion. Genetic Algorithm is then applied to optimize the sensor location and quantity. Differences in the sensor system design resulting from the two airflow models are discussed for a typical office environment and a large hall environment. http://idea.library.drexel.edu/handle/1860/2596 Title: Evaluating in-home water purification methods for communities in Texas on the border with Mexico <br/> <br/>Authors: Gurian, Patrick L.; Camacho, Gema; Park, Jun-young; Cook, Steve R.; Mena, Kristina D. <br/> <br/>Abstract: This study evaluated user preferences among three alternative in-home water treatment technologies suitable for households relying on trucked water in El Paso County, Texas, which is on the border with Mexico. The three technologies were: chlorination of household storage tanks, small-scale batch chlorination, and point-of-use ultraviolet disinfection. Fifteen households used each of the three technologies in succession for roughly four weeks each during April through June of 2004. Data were collected on treated water quality, and a face-valid survey was administered orally to assess user satisfaction with the technologies on a variety of attributes. Treatment with a counter-top ultraviolet disinfection system received statistically significantly higher ratings for taste and odor and likelihood of future use than the other two approaches. Ultraviolet disinfection and small-scale batch chlorination both received significantly higher ratings for ease of use than did storage tank chlorination. Over-chlorination was a common problem with both batch chlorination and storage tank chlorination. Water quality in the households using trucked water is now higher than was reported by a previous study, suggesting that water quality has improved over time. http://idea.library.drexel.edu/handle/1860/2562 Title: Limitations in structural identification of large constructed structures <br/> <br/>Authors: Catbas, F.N.; Ciloglu, Suleyman Korhan; Hasancebi, O.; Grimmelsman, Kirk Alexander; Aktan, Ahmet Emin <br/> <br/>Abstract: The objective of this paper is to discuss the limitations in structural identification of large constructed structures. These limitations arise due to the geometric complexity, uncertain boundary and continuity conditions, loading environment, and the imperfect knowledge and errors in modeling such large constructed facilities. In this paper, the writers present their studies on developing a mixed microscopic-structural element level three-dimensional finite-element FE modeling of a long-span bridge structure and its structural system identification by integrating various experimental techniques. It is shown that a reasonable level of confidence 50–90% can be achieved with a model that is calibrated using global and local structural monitoring data with a sufficiently high spatial resolution. The reliability of the global attributes, such as boundary and continuity conditions that may be identified and simulated by means of field-calibrated models using only dynamic test results globally calibrated models , may appear to be high as much as 90% . However, the reliability that should be expected for local stress fields is shown to be an entirely different matter, and a calibration based on just dynamic testing would be unable to reveal the confidence in simulated local responses. This is especially true for long-span bridges, because the resolutions of the dynamic test grids are often quite sparse due to the large size of the structures. In this paper, the writers illustrate that the density, modality, and bandwidth of experimental data should be carefully evaluated and matched to the size and complexity of a constructed system before claiming that a FE model is validated. It is also shown that even more than three dozen acceleration measurement points, two dozen strain measurements, and a continuous surveillance of wind and temperature were barely sufficient for a credible structural identification of a long-span bridge. http://idea.library.drexel.edu/handle/1860/2537 Title: The twenty greatest engineering achievements of the Twentieth Century <br/> <br/>Authors: Koerner, Robert <br/> <br/>Abstract: Greatest engineering achievements of the twentieth century in the following categories: 1. Electrification -- 2. Automobile -- 3. Airplane -- 4. Water supply and distribution -- 5. Electronics -- 6. Radio and television -- 7. Agricultural mechanization -- 8. Computers -- 9. Telephone -- 10. Air conditioning and refrigeration -- 11. Highways -- 12. Spacecraft -- 13. Internet -- 14. Imaging -- 15. Household appliances -- 16. Health technologies -- 17. Petroleum and petrochemical technologies -- 18. Laser and fiber optics -- 19. Nuclear technologies -- 20. High-performance materials. <br/> <br/>Description: 2006175364a: Short Version; 2006175364b: Full Version http://idea.library.drexel.edu/handle/1860/2027 Title: Investigation of 1-g similitude laws by “modeling-of-models” <br/> <br/>Authors: Ozkahriman, F.; Wartman, Joseph <br/> <br/>Abstract: This paper presents the results of a “modeling-of-models” laboratory exercise conducted in a 1-g environment to investigate the applicability and validity of established similitude laws. The study, which was performed under static condition, considers the behavior of cohesive model slopes at small (stiffness) and large strains (failure). The test program involved three small-scale model slopes tested under different geometry scaling factors. The models were comprised of an artificial, fully saturated "model" clay (3 parts kaolinite to 1 part bentonite). The results indicate that for fully saturated cohesive soils tested under undrained conditions, similitude laws are valid for static conditions provided that three dimensional effects and boundary conditions are properly accounted for. http://idea.library.drexel.edu/handle/1860/2006 Title: A Bayesian Monte Carlo approach to model calibration for queuing systems <br/> <br/>Authors: Gurian, Patrick L.; Castro, Felipe; Chiu, Yi-Chang <br/> <br/>Abstract: Calibrating models of queuing processes typically requires the collection of data on the arrival and departure of individual vehicles. In this paper an alternative procedure is described which uses Bayesian Monte Carlo methods to update prior estimates of model parameters using observations of changes in queue length over time. Substantial reductions in parameter uncertainty can be achieved by this calibration procedure. The procedure is most effective at reducing uncertainty in arrival rates when service rates are already well characterized. A number of transportation systems, including toll plazas and inspections stations at ports-of-entry, have well-characterized service capacities, indicating that this method may be appropriate for use with these systems. In general, posterior uncertainties for arrival rates and service rates are higher than for conventional calibration procedures. This procedure is likely to be useful in cases, such as international ports-of-entry, where security and access concerns render the collection of data on individual vehicles infeasible, but abundant information is available on queue lengths. http://idea.library.drexel.edu/handle/1860/1987 Title: Improving energy efficiency and temperature control in a passive-solar housing development <br/> <br/>Authors: Gurian, Patrick L.; Martinez, Victor; Cook, Steve R. <br/> <br/>Abstract: Tierra Madre is a community of 47 straw bale homes and a community center located in Sunland Park, NM, northwest of El Paso, TX. Tierra Madre represents an alternative model of resourceful energy-efficient construction. These homes are built in accordance with the concept of passive-solar design and integrate both energy-efficient and affordability concepts for low-income people. Despite the passive-solar and energy-efficient design, a diverse number of problems were identified in the first homes constructed at Tierra Madre. These flaws were corrected in the construction of subsequent homes. Utility data were then collected to determine if the homes are energy-efficient. Based on the information obtained from household utility bills, Tierra Madre homes can be considered energy-efficient homes. This paper will outline the steps taken towards the improvement of energy use and occupant comfort in Tierra Madre. http://idea.library.drexel.edu/handle/1860/1986 Title: Regulating drinking water quality incrementally: better than benefit-cost analysis? <br/> <br/>Authors: Gurian, Patrick L. <br/> <br/>Abstract: The use of benefit-cost analysis has expanded over the last twenty five years and now plays a key role in the formulation of new regulations, even regulations for the protection of human health. Regulatory decision making is, of necessity, based on pre-regulatory paper studies of costs and benefits. There has been relatively little post-regulatory validation of these benefit-cost estimates, but what little information is available indicates that they are most often inaccurate. Roughly half of such estimates have been found to over-estimate costs by failing to anticipate technological change driven by the regulation. Roughly a quarter of studies underestimated costs by failing to anticipate unintended consequences of the regulation. Estimates of benefits are often impossible to verify even after the regulation is imposed as they involve small changes in cancer rates that are not distinguishable from random fluctuations in epidemiological data. Basing decisions on a tool that is so often in error would appear to be ill advised. Unfortunately the alternatives are not very attractive. Basing decisions on absolute standards of health protection does not allow for the prioritization of limited resources. In practice it can result either in overly strict regulation, in the hopes of completely eliminating risk, or in inaction, as regulators wait for absolute scientific certainty before imposing stringent and costly regulations. An alternate regulatory procedure based on incremental regulatory changes is described and statutory changes proposed to give EPA discretionary authority to adopt such a strategy for setting drinking water standards. This strategy will aim to avoid large, irreversible investments with uncertain benefits. This strategy will shift the emphasis from the largely inaccurate pre-regulatory benefit-cost assessments towards ongoing studies of regulatory impacts that will provide feedback to governmental agencies.