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Time-dependent strength gain of a nonproprietary ultrahigh-performance concrete
Published in Hiroshi Yokota, Dan M. Frangopol, Bridge Maintenance, Safety, Management, Life-Cycle Sustainability and Innovations, 2021
M.P. Manning, T.S. Alahmari, B.D. Weldon
Time-dependent compressive strength data for thermal curing (TC) and ambient curing (AC) regimens are compared in Figure 3. The average compressive strength for each test day (based on specimen age at testing) is presented with TC specimens indicated in black and AC specimens indicated in gray. Error bars are included representing the standard deviation of the data. Results indicate TC specimens typically reached approximately 90% of their 7-day strength within the first 48 hours after casting, and with only 24 hours of elevated thermal curing. Achieving an average compressive strength of 143 MPa at seven days, compressive strengths for TC specimens remained relatively constant with increasing age. Operating under the assumption that strength gain would occur less rapidly for the ambient curing regimen, testing of AC specimens commenced three days after casting. Producing an average compressive strength of 111 MPa at seven days, AC strength gain was much more gradual in comparison to TC specimens, and strengths continued to increase through the first month after casting. When comparing specimens with a minimum age of 28 days, the average compressive strength for AC specimens was 134 MPa, or approximately 93% of the comparative 144 MPa average for TC specimens. It should be noted that samples were tested for all batches at the 7-day reference age, and sample set sizes tend to decrease with age.
Regression and Correlation
Published in Patrick F. Dunn, Fundamentals of Sensors for Engineering and Science, 2019
Caution should be exercised when claims are made about trends in the data. Any claim must be made within the context of measurement uncertainty that is assessed at a particular confidence level. An example is illustrated in Figure 14.13. The same values of five trials are plotted in each of the two figures. The trend in the values appears to increase with increasing trial number. In the top figure, the error bars represent the measurement uncertainty assessed at a 95 % level of confidence. The solid line suggests an increasing trend, whereas the dotted line implies a decreasing trend. Both claims are valid to within the measurement uncertainty at 95 % confidence. In the bottom figure, the error bars represent the measurement uncertainty assessed at a 68 % level of confidence. It is now possible to exclude the claim of a decreasing trend and support only that of an increasing trend. This, however, has been done at the cost of reducing the confidence level of the claim. In fact, if the level of confidence is reduced even further, the claim of an increasing trend cannot be supported. Thus, a specific trend in comparison with others can only be supported through accurate experimentation in which the error bars are small at a high level of confidence.
Temperature Fluctuation and Frost Risk Analysis on a Road Network by Coupling Remote Sensing Data, Thermal Mapping, and Geographic Information System Techniques
Published in George P. Petropoulos, Tanvir Islam, Remote Sensing of Hydrometeorological Hazards, 2017
Panagiota Louka, Ioannis Papanikolaou, George P. Petropoulos, Nikolaos Stathopoulos, Ioannis X. Tsiros
The profiles of road surface, air, and LST are displayed in Figure 9.8a. In the RST and LST temperature profile, error bars are included to indicate their margins of error. These were defined with the strictest error limits, according to the specification of the initial data. More specifically, an error bar of 2°C was applied, which is the estimated accuracy of the thermography measurements (Bouris et al. 2010). Accordingly, the LST error bar was defined to be 1°C, as this is the estimated accuracy of MODIS LST products, in land and under clear sky conditions (https://modis.gsfc.nasa.gov/data/atbd/atbd_mod11.pdf). The error bars are useful because they signify whether differences between the datasets are statistically important or if the displayed datasets are in agreement.
Effect of stretch ratio on the induced crystallinity and mechanical properties of biaxially stretched PET
Published in Phase Transitions, 2020
In the same vein, the tensile tests showed low margins of error. Figure 10 shows an example of the error analysis carried out on all the results from the tensile tests. This example is for the 3 × 3 sample. The error bars indicate the variability of the data presented in the graph. They show the margins of error of the data in both the vertical and the horizontal directions. In other words, they show how far from the true value the determined (or reported) value is. As shown in Figure 10, the margins of error generally increased as the experiment progressed. Meantime, it was observed that the results from the repeated tests of each experiment mostly lay within the margins of error shown by the error bars on the graph of the reported average. Therefore, the overall estimated percentage error from the tensile tests was 0.99%.
Material Studies to Reduce the Tritium Memory Effect in BIXS Analytic Systems
Published in Fusion Science and Technology, 2020
Figures 3 and 4 show the relative memory effect plotted over the exposure. is the count rate during the evacuation, and is the count rate during the exposure preceding the evacuation. The ratio is plotted to guarantee comparability of the values despite the material-dependent count rates and to eliminate potential detector systematics. The error bars display the statistical uncertainties on the data points. The Ti-W coating shows the expected high memory effect being exceeded only by the memory effect of the Ir coating. For both the Ti-W coating and the Ir coating, a saturation behavior that changes into a linear increase can be seen.
Thermal Hydraulics of Helium-Cooled Finger-Type Divertors at Higher Incident Heat Fluxes
Published in Fusion Science and Technology, 2019
D. S. Lee, S. A. Musa, S. I. Abdel-Khalik, M. Yoda
The average HTC where the area of the cooled surface is = 184 mm2. This assumes that all of the heat is transferred to the helium via convection at the cooled surface. The average dimensionless HTC, or Nusselt number, . k is the helium thermal conductivity evaluated at the average of the inlet and outlet helium temperatures. The results are shown in Fig. 5 as a function of Re, where the filled symbols indicate the results obtained with the new Pyrex–stainless steel enclosure, and the open symbols summarize previous results4 at ≤ 2.9 MW/m2. The error bars represent the experimental uncertainty. These results show that is effectively independent of Ti and , in agreement with similarity and previous work.4