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Effects of Frost on the Structure and Properties of Concrete
Published in Boris A. Krylov, Cold Weather Concreting, 2020
In addition to the mechanically bound water, fresh concrete contains some amount of adsorptionally or physically bound water which changes to ice at lower temperatures. This water is held on the surfaces of mineral particles, which have a surface energy, by electromolecular forces to which water is particularly sensitive because of the polarity of its molecules. The strength of binding water molecules by mineral particles is governed by the surface electromolecular field and depends on the intensity of the field. The latter is a rapidly decreasing function of the distance from the surface of a particle. So the electromolecular forces are enormous very close to the surface (in the order of one or two diameters of the molecules) and diminish fast with the distance. This determines the degree of bonding of water layers at different distances from the surfaces of mineral particles. The most remote layers become solid at a higher subzero temperature than those that lie nearer to the surface. The molecular layers of water on the surfaces of solid particles have gigantic surface tension forces, remain liquid even at -190°C, and are close to solids in their properties.
Inverse Problems for Equations With Memory
Published in G Nakamura, S Saitoh, J K Seo, M Yamamoto, Inverse problems and related topics, 2019
Alexandre L. Bukhgeĭm, Gleb V. Dyatlov
Thus, ω(x) ≡ k−1(x) and the coefficients kj(x), j ≥ 0, are uniquely determined by the coefficients vj(x,x). Recall that k(x,t) = k0(x,t) + k1(x,t). Here k0(x,t) is a known function rapidly decreasing in time, thereby its Fourier transform k^0(x,λ) is infinitely differentiable with respect to λ and for every N ∈ ℕ we have the expansion k^0(x,λ)=∑j=0Nk0j(x)(iλ)j+o(λN).
Integral equations of convolution type on unions of intervals
Published in C Constanda, J Saranen, S Seikkala, Integral methods in science and engineering, 2020
For functions φ in the space S(ℝ) of rapidly decreasing functions on ℝ, the Fourier transform is defined by ℱφ(ξ)=∫ℝeiξxφ(x)dx.
Grizzly and BlackBear: Structural Component Aging Simulation Codes
Published in Nuclear Technology, 2021
Benjamin W. Spencer, William M. Hoffman, Sudipta Biswas, Wen Jiang, Alain Giorla, Marie A. Backman
The RPV geometry and dimensions used here are based on publicly available information on a typical four-loop PWR pressure vessel, but do not represent a specific RPV. To idealize the nonuniform temperature conditions, a plume region emanating downward from the inlet is identified, as shown on the model in Fig. 3. A transient temperature and pressure history that has been used in other PTS analyses assuming spatially uniform conditions is used as the basis for the transient applied here and is applied to the balance of the inner surface of the RPV, while a more rapidly decreasing temperature function is used in the plume region. As can be seen in Fig. 3, which shows the temperature at time = 120 s there is a region between the plume and nonplume regions over which the temperature linearly transitions between the two functions.
Geoenvironmental behavior of lime-treated marine sediments
Published in Marine Georesources & Geotechnology, 2021
Aditya S. Deshmukh, Asli Y. Dayioglu, Ahmet H. Aydilek
Although EPA WQL has not been prescribed for cobalt (Co), it is known that this metal can be highly toxic to living organisms (Linna et al. 2004). A limit of 1.5 mg/L has been proposed in past studies due to its harmful effects to living organisms (Valdez-Vega et al. 2011). First-flush pattern is observed from D1, D2, and D3 with a distinct peak initially (PV = 0), and concentrations rapidly decreasing as a function of pore volume. Effluent from columns of lime-amended DM consistently show Co concentrations below the detection limit of 0.2 mg/L (Table 5 and Figure 6). Elution of Co increases with increase in acidity and iron content, while manganese reduces the mobility of cobalt (Dong et al. 2007). Considerable amounts of manganese and iron exist in pure DM (Table 2), which may have potentially influenced the leaching behavior of cobalt. Co leaching from pure and lime-amended DM falls below 1.5 mg/L, a limit proposed by Valdez-Vega et al. (2011), after 2–3 pore volumes of flow and use of ES in highway construction significantly reduces the risk of Co leaching (Figure 6). First-flush pattern is observed for D2-ES due to significant amount of Co leaching from D2 column (up to 3.78 mg/L). A steady-state leaching pattern is observed for D1-ES, although the pattern is not evident from the graph as the concentrations are found to be very close to the detection limit. Buffering capacity of ES significantly affects the mobilization of Co due to adsorption on the surface of ES, thus reducing concentrations of Co in the effluent.
Intra-cell ionic properties of twisted nematic liquid crystal cells
Published in Liquid Crystals, 2019
A large slope on the Ph–VLC curves occurred at Vapp = 1.3 V that was later used as the amplitude of a square wave at 0.1 Hz for the measurements of phase retardation versus time (Ph–t curve) and current versus time (I–t curve) for our samples. After about 50 ms, the time to complete LC-director reorientations in the TN cell by the external field, if no mobile ions existed within the LC medium and PI layers, the measured Ph–t curves shown in Figure 5 should have been a constant, independence of time. However, in Figure 5, the experimental results on Sample 2 showed a rapidly decreasing phase retardation as a function of time, implying that there were more mobile ions moving from PI sides than that from LC side to accumulate on or at proximities of the PI–LC interfaces resulting in a net ionic field, Eion (t) = EPI (t) − ELC (t) > 0 (enhance effect[3]) as observed. However, the experimental results of Sample 1 showed that the measured phase retardation increased slowly with time, implying that Eion (t) = EPI (t) − ELC (t) < 0 (screening effect [3]) as shown in Figure 5.