A review on performance – based specification of durable concrete

Concrete is the most common and widely used building material because of its relatively low cost, flexibility, and adaptability. Recent historical experience indicates that with exposed to aggressive chloride or carbonation-induced conditions, the reinforced concrete (RC) structures deteriorate prior to the expected service life. This is because of the general assumption that the concrete must be sufficiently durable if the strength requirements are adequate. The variability of concrete arising from the actual concreting procedures, such as placement, consolidation, finishing, and curing, does not take this assumption into account. In other words, the concrete cast for compressive strength in the specimens shows no similarity to the concrete in the actual structure. This paper provides a thorough analysis of the advancements that are taking place to achieve the long-term reliability of RC structures based on performance specifications. Keywords: reinforced concrete, service life, compressive strength, performance specification, durability, carbonation, chloride ion

Contribution of wetted clothing to body energy exchange and heat stress

Citation: Elson, J., & Eckels, S. (2018). Contribution of wetted clothing to body energy exchange and heat stress. Journal of Thermal Biology, 78, 343–351. https://doi.org/10.1016/j.jtherbio.2018.09.014Quantifying the impact of clothing thermal and evaporation resistance is essential to providing representative boundary conditions for physiological modeling. In many models, sweat is assumed to drip off the skin surface to the environment and is not captured in clothing. In high metabolic rate and high temperature and humidity conditions the sweat produced by the body has the potential to saturate semipermeable clothing ensembles, changing the assumptions of the model. Workers, athletes and soldiers commonly wear encapsulating versions of such clothing to protect against environmental hazards. A saturated clothing model is proposed based on the ASHRAE two-node model using a saturated spot element in parallel with the existing method to account for sweat absorbed in the clothing. The work uses fundamental heat and mass transfer principles, modifying the existing formula using clothing measurements and basic assumptions. The effectiveness of the model is demonstrated by comparing the predictions of the original and proposed models, to the results of 21 soldiers exercising. The soldiers wore combat pants and shirt, helmet, gloves, shoes, socks, and underwear, and walked in a thermal chamber for 2 h at 42.2 °C dry bulb temperature, 54.4 °C wet bulb temperature, 20% relative humidity, and airspeed of 2 m/s. Core temperature, seven skin temperatures, heart rate, and total sweat loss were measured. The original model provides an average core temperature difference compared with the human subject results of 1.31 °C (SD = 0.557 °C) while the modified model improves the final prediction of core temperature to within an average of 0.15 °C (SD = 0.383 °C). The new model shows an improvement in the prediction of human core temperature under the tested conditions where dripping sweat will saturate clothing. The format can be used in multi-segmented thermal models and can continue to be developed and improved as more information on wetted clothing properties become available

The Ages and Abundances of the M87 Globular Clusters

A subset of 150 globular clusters in M87 has been selected on the basis of S/N ratio for abundance and age determinations from the sample of Paper I. Indices measuring the strength of the strongest spectral features were determined for the M87 GCs and from new data for twelve galactic GCs. Combining the new and existing data for the galactic GCs and comparing the $(U-R)$ colors and the line indices gives qualitative indications for the ages and abundances of the GCs. Quantitative results are obtained by applying the Worthey (1994) models for the integrated light of stellar systems of a single age, calibrated by observations of galactic GCs, to deduce abundances and ages for the objects in our sample. We find that the M87 GCs span a wide range in metallicity, from very metal poor to somewhat above solar metallicity. The mean [Fe/H] of -0.95 dex is higher than that of the galactic GC system, and there is a metal rich tail that reaches to higher [Fe/H] than one finds among the galactic GCs. The mean metallicity of the M87 GC system is about a factor of four lower than that of the M87 stellar halo at a fixed projected radius $R$. The metallicity inferred from the X-ray studies is similar to that of the M87 stellar halo, not to that of GCs. We infer the relative abundances of Na, Mg, and Fe in the M87 GCs from the strength of their spectral features. The behavior of these elements between the metal rich and metal poor M87 GCs is similar to that shown by the galactic GCs and by halo stars in the Galaxy. The pattern of chemical evolution in these disparate old stellar systems is indistinguishable. We obtain a median age for the M87 GC system of 13 Gyr, similar to that of the galactic GCs, with a small dispersion about this value.Comment: 56 pages with included postscript figures; added derived M87 GC metallicities to Table 2, a statistical analysis of possible bimodality, an appendix on the metallicity calibration of U-R and the Washington system, and other smaller changes. Accepted for publication in ApJ. (See paper for complete version of the Abstract.

Vagueness, truth, and nothing else

This paper is an investigation into the relationship between vagueness and deflationary accounts of truth. I outline both, and give reason to think that vagueness is an essential feature of our language. Then I argue that deflationary accounts of truth are unable to capture the Supervaluationist account of vagueness, because of that theory's nonclassical nature. I give reasons to think that deflationism will have problems with any satisfactory account of vagueness

An Introduction to Value-Added Analysis

For the last 3 years, more than 80% of the respondents to Annual Phi Delta Kappa/Gallup Poll of the Public’s Attitudes Toward The Public Schools have stated that they would rather see a school’s performance measure based upon “improvement shown by students” than the “percentage passing the test” (Rose & Gallip, 2007, p. 35). If this were to become the norm, the next question would be what “improvement” is significant? Educators need to understand “value-added” if they are going to use “improvement” to show that schools are improving student achievement

Let’s talk about sex history: impact of a communication curriculum on medical student performance and perceived competency

Introduction: Communication in general, but especially regarding difficult topics such as sexual health is inadequately addressed in undergraduate medical education. Students often feel they are poorly trained in this area due to a lack of opportunities to practice taking sexual history. Thus, a communication curriculum was implemented to address this gap, including formal small group practice sessions on taking a sexual history during the Obstetrics and Gynecology (OB/GYN) clerkship. Aim: Determine whether medical students who completed a sexual history communication curriculum performed better during a formal standardized patient based assessment (PBA) at the conclusion of the OB/GYN clerkship than historical control medical students, and assess medical student perception about taking a sexual history. Methods: Retrospective study comparing 3 specific PBA standardized patient rating questions and 5 questions gathering medical student feedback at a single academic institution. All (n=71) medical students between January and June 2011 were queried at the conclusion of their OB/GYN clerkship prior to implementation of the sexual history curriculum in July 2011 with responses compared to all subsequent (n=432) medical students through June 2014. Main Outcome Measures: Cochran-Mantel-Haenszel was used to compare scores by clerkship year and block with p<0.05 significant. Results: There was no change in medical student PBA performance or medical student perception regarding ability to take a sexual history following implementation of the sexual history communication curriculum. However, in response to “what other instruction or experiences could the clerkship provide to help you gain competency,” the theme was more practical experience. Conclusion: Learners require different formats to promote and enhance learning which may not have been measured with the outcomes chosen for this study. This may be best achieved by implementation of a formal curriculum including explicit supplementation to incorporate additional experience with sexual history taking

Maximising Achievable Rates of Experimental Nonlinear Optical Fibre Transmission Systems

It is generally expected that the demand for digital data services will continue to grow, placing ever greater requirements on optical fibre networks which carry the bulk of digital data. Research to maximise achievable information rates (AIR) over fibre has led to increasing spectral efficiency, symbol rate and bandwidth use. All of these contribute to transmission impairments due to the nonlinear nature of the optical fibre. This thesis describes research performed to investigate the effects of nonlinear impair- ments on the AIRs of experimental optical fibre transmission. To maximise throughput, the entire available optical bandwidth should be filled with transmission channels. An investigation into large bandwidth transmission through the use of spectrally shaped amplified spontaneous emission noise (SS-ASE) was con- ducted. The enhanced Gaussian noise model is used to analytically describe this tech- nique, and SS-ASE was experimentally shown to provide a lower bound on the AIR. Nonlinear interference (NLI) was modelled from an inter-symbol interference (ISI) model to characterise the noise and was experimentally verified. This new understand- ing helps quantify potential gain available from nonlinearity mitigation. Multicore fibres offer an alternative route to improve AIR, and are susceptible to another noise source known as crosstalk. This inter-core crosstalk can be controlled by suitable design of the fibre, hence in the limiting case, NLI rather than crosstalk will limit AIR. Nonlinearity compensation was, for the first time, experimentally demon- strated in the presence of crosstalk in a homogeneous 7-core fibre and shown to provide an increase in AIR. The results of this thesis can be used to evaluate future transmission systems for maximising information rates. It was shown that experimentally, SS-ASE is a viable transmission tool to evaluate system performance, NLI can be characterised using an ISI model and nonlinearity mitigation is possible in MCF systems limited by crosstalk

Evaluation of personal cooling systems and simulation of their effects on human subjects using basic and advanced virtual environments

Doctor of PhilosophyDepartment of Mechanical and Nuclear EngineeringSteven J. EckelsThe research presents the investigation of personal cooling systems (PCS) and their effects on humans from a thermodynamic perspective. The original focus of this study was to determine the most appropriate PCS for dismounted U.S. Army soldiers in a desert environment. Soldiers were experiencing heat stress due to a combination of interrelated factors including: environmental variables, activity levels, and clothing/personal protective equipment (PPE), which contributed to the buildup of thermal energy in the body, resulting in heat stress. This is also a common problem in industry, recreation, and sports. A PCS can serve as a technological solution to mitigate the effects of heat stress when other solutions are not possible. Viable PCS were selected from the KSU PCS database, expanded to over 300 PCS in the course of this study. A cooling effectiveness score was developed incorporating the logistical burdens of a PCS. Fourteen different PCS configurations were tested according to ASTM F2370 on a sweating thermal manikin. Four top systems were chosen for ASTM F2300 human subject testing on 22 male and 2 female soldiers in simulated desert conditions: dry air temperature = 42.2 ºC, mean radiant temperature = 54.4 ºC, air velocity = 2.0 m/s, relative humidity = 20%. Subjects wore military body armor, helmets and battle dress uniforms walking on treadmills at a metabolic rate of approximately 375-400W. All the PCS conditions showed significant reductions in core temperature rise, heart rate, and total sweat produced compared to the baseline (p<0.05). The expected mean body temperature was higher in the human subjects than expected based on the cooling obtained from the sweating manikin test. Lowered sweat production was determined to be the likely cause, reducing the body’s natural heat dissipation. The ASHRAE two-node model and TAITherm commercial human thermal models were used to investigate this theory. A method to account for fabric saturation from dripping sweat was developed and is presented as part of a new model. This study highlights that the response of the human body is highly complex in high-activity, high-temperature environments. The modeling efforts show the PCS moved the body from uncompensable to compensable heat stress and the body also reduced sweating rates when the PCS was used. Most models assume constant sweating (or natural heat loss) thus the PCS sweat reduction is the likely cause of the higher than expected core temperatures, and is an important aspect when determining the purpose of a PCS