STEADY STATE MODELING OF WET STEAM IN A PIPING SYSTEM

Current designs for steam piping systems are predicated on conservative deterministic design approaches to prevent the admission of moisture. This design approach may result in excess conservatism and larger, more inefficient components. During normal steady-state operations, the steam system operates with high-quality saturated steam, and moisture admission is not a concern. However, implementing design parameters for possible transient conditions can lead to components whose potential may never be fully utilized, adding inefficiencies. This effort seeks to identify features and physics of the piping system that can be used to challenge previous design criteria and show that off-design conditions for short durations can be mitigated. These types of features include the locations of piping bends and steam traps. This effort focuses on a steady state analysis of a wet saturated steam piping system and develops and implements a computational fluid dynamics (CFD) model for qualitatively evaluating the effect of droplet size and inlet quality on the behavior of a two-phase saturated steam flow. Additional modeling using TRAC/RELAP Advanced Computational Engine (TRACE) was performed to determine the code’s suitability for modeling a saturated steam system. The models developed in this effort will be used as the foundation for follow-on research of transient conditions.NAVSEA 08TOutstanding ThesisLieutenant, United States NavyApproved for public release. Distribution is unlimited

Influence of Adhesion at Steel/Mortar Interface on Corrosion Characteristics of Reinforcing Steel

The mechanism of corrosion of reinforcing steel in concrete is discussed based on electrochemical and electron microscopy observations. The importance of calcium hydroxide precipitation on the steel surf ace in the steel/mortar interface is evaluated by placing filter paper around reinforcing steel bar specimens prior to casting in mortar, thus preventing direct contact between steel and mortar. The voids created presumably prevent calcium hydroxide crystals from forming on the steel surface. Specimens with filter paper are compared to specimens with good steel/mortar adhesion using rapid macrocell and corrosion potential tests and a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). The study included 21 macrocell and 16 corrosion potential tests run for periods of 25 to 89 days. Seven specimens were subjected to SEM/EDS analysis. Electrochemical results are mixed due to the influence of crevice corrosion. but it is generally shown that better protection is provided for steel with good steel/mortar adhesion than with filter paper. The filter paper, indeed, prevents calcium hydroxide crystals from forming on the steel surface. Corrosion products on active specimens with good mortar cover are shown to grow preferentially in voids created by air bubbles trapped in the mortar. The protective mechanism of calcium hydroxide crystals is proposed to be due to pH buffering by the hydroxyl ions released when the crystals are dissolved, a fact that cannot be proven easily, since many other factors may contribute to the protection of steel in concrete. This report is based on research by Henrik J. Axelsson in partial fulfillment of the requirements of the M.Sc. degree in Engineering Physics at Chalmers University of Technology, Gothenburg. Sweden. The research was sponsored by the Department of Civil and Envirorunental Engineering at the University of Kansas and by Structural Metals, Inc

A field experiment on the impact of sounds from a jet-and-basin fountain on soundscape quality in an urban park

AbstractA field experiment was conducted to explore whether water sounds from a fountain had a positive impact on soundscape quality in a downtown park. In total, 405 visitors were recruited to answer a questionnaire on how they perceived the park, including its acoustic environment. Meanwhile the fountain was turned on or off, at irregular hours. Water sounds from the fountain were not directly associated with ratings of soundscape quality. Rather, the predictors of soundscape quality were the variables “Road-traffic noise” and “Other natural sounds”. The former had a negative and the latter a positive impact. However, water sounds may have had an indirect impact on soundscape quality by affecting the audibility of road-traffic and natural sounds. The present results, obtained in situ, agree with previous results in soundscape research that the sounds perceived—particularly roadtraffic and natural sounds—explain soundscape quality. They also agree with the results from laboratory studies that water sounds may mask road-traffic sounds, but that this is not simple and straight forward. Thus sound should be brought into the design scheme when introducing water features in urban open spaces, and their environmental impact must be thoroughly assessed empirically

Disseminating evidence from health technology assessment : the case of tobacco prevention

OBJECTIVES: The aims of the present study were to investigate the awareness among dentists and dental hygienists of evidence-based reports and guidelines on tobacco cessation activities and the impact these publications had on clinical practice. METHODS: A questionnaire was mailed to dental hygienists and dentists in Stockholm County, Sweden, and the results were compared with a previous investigation. RESULTS: Among the respondents, awareness of a popular science version of a systematic review on smoking and its effect on oral health was reported by 90 percent of the hygienists and 66 percent of the dentists. The information was used in clinical work by 34 percent of the dentists and 54 percent of the hygienists. Reported changes in patterns of practice were more frequent recommendations to use nicotine replacement therapy and a more widespread use of setting quit dates. Approximately one quarter of the dental professionals reported that they had increased tobacco cessation consultation because of the results from the reports. CONCLUSIONS: Changes in patterns of practice were observed after dissemination of evidence-based information on tobacco cessation. Methods that were proven to be effective in the evidence-based report such as discussing quit dates and recommending nicotine replacement therapy were more commonly used after the publication of the report. Short, popular versions of extensive systematic reviews seem to be useful for implementing evidence-based knowledge and changing clinical practice.NonePublishe

Categorization of indoor places by combining local binary pattern histograms of range and reflectance data from laser range finders

This paper presents an approach to categorize typical places in indoor environments using 3D scans provided by a laser range finder. Examples of such places are offices, laboratories, or kitchens. In our method, we combine the range and reflectance data from the laser scan for the final categorization of places. Range and reflectance images are transformed into histograms of local binary patterns and combined into a single feature vector. This vector is later classified using support vector machines. The results of the presented experiments demonstrate the capability of our technique to categorize indoor places with high accuracy. We also show that the combination of range and reflectance information improves the final categorization results in comparison with a single modality

Separation of Test-Free Propositional Dynamic Logics over Context-Free Languages

For a class L of languages let PDL[L] be an extension of Propositional Dynamic Logic which allows programs to be in a language of L rather than just to be regular. If L contains a non-regular language, PDL[L] can express non-regular properties, in contrast to pure PDL. For regular, visibly pushdown and deterministic context-free languages, the separation of the respective PDLs can be proven by automata-theoretic techniques. However, these techniques introduce non-determinism on the automata side. As non-determinism is also the difference between DCFL and CFL, these techniques seem to be inappropriate to separate PDL[DCFL] from PDL[CFL]. Nevertheless, this separation is shown but for programs without test operators.Comment: In Proceedings GandALF 2011, arXiv:1106.081

One step multiderivative methods for first order ordinary differential equations

A family of one-step multiderivative methods based on Padé approximants to the exponential function is developed. The methods are extrapolated and analysed for use in PECE mode. Error constants and stability intervals are calculated and the combinations compared with well known linear multi-step combinations and combinations using high accuracy Newton-Cotes quadrature formulas as correctors. w926020