Limited effect of diameter of fibres on spalling protection of concrete in fire

This study investigates the effect of diameter, length and melting point of fibres on spalling protection of concrete in fire. Three different diameters (0.012, 0.02 and 0.04 mm), three different lengths (9, 12 and 19 mm) and two different types (nylon and polypropylene) of fibres were investigated. Fibre volume (v%) or fibre weight per unit volume of concrete are commonly used parameters for fibre addition, but are dependent parameters on diameter of fibres. This study reports a better parameter for the expression of fibre addition which is independent of diameter, namely, number of fibres per cubic centimeter (N). When 12 mm length polypropylene fibre addition is expressed by v%, the minimum requirement for spalling protection is v = 0.20% for 0.04 mm diameter fibres and v = 0.05% for 0.02 mm diameter fibres. If the fibre addition is expressed in N, the minimum requirement is N = 133/cm³ for both cases regardless of fibre diameter. Hence, the diameter of fibres has limited effect on spalling protection of concrete. If the fibre addition is expressed in v%, the diameter seems to have an effect due to the fact that parameter v% is a function of diameter. In addition, increasing the length of fibres has the effect of reducing the required N for spalling protection. When fibre length is increased from 12 to 19 mm, the minimum requirement is reduced from N = 133 to 42/cm³. The melting point of the fibres also has an influence on spalling protection, which is discussed in detail by comparing nylon and polypropylene fibre results.     

Probabilistic seismic risk analysis of CANDU containment structure for near-fault earthquakes

In this study, the seismic risk of a CANDU (CANada Deuterium Uranium) containment structure is estimated by performing the nonlinear seismic analysis for the near-fault earthquakes. Nonlinear seismic analysis is more effective to consider the distinct nonlinear behavior of concrete structures subjected to the near-fault ground motion which has high input energy. In Korea, the seismic fragility analysis has been performed by using the design analysis results which were obtained from a linear elastic analysis.The lumped mass model of the containment structure was used for a nonlinear dynamic time history analysis. The tri-linear skeleton curve was used for the nonlinear behavior of the prestressed concrete containment structure. In order to estimate the inelastic nonlinear response of the containment, the maximum point-oriented model was used for the hysteretic rule of the shear deformation.For the nonlinear seismic analyses, 30 set of real near-fault earthquake records were used as the input motion. The seismic fragility and risk of the containment for the near-fault ground motions are compared with those from the results based on the conventional method.     

Effects of persimmon-vinegar on lipid and carnitine profiles in mice

The aim of this study was to investigate the effects of persimmon-vinegar supplementation on blood lipid profiles, carnitine concentrations, and hepatic mRNA levels of enzymes involved in fatty acid metabolism. Thirty-two C57BL/6J male mice were divided into 4 groups; control group (HD), industrial vinegar group (HD-V), and persimmon-vinegar groups (HD-PV1, HD-PV2). Serum triglyceride (TG) and total cholesterol (TC) concentrations significantly decreased in all vinegar-administered groups compared with the HD group. The hepatic TG and TC concentrations of persimmon-vinegar administered groups were significantly lower compared with the HD group. Liver acid insoluble acylcarnitine (AIAC) was significantly higher in the HD-PV2 than in HD and HD-V groups. The acetyl-CoA carboxylase (ACC) mRNA level tended to lower in all the vinegar administered groups compared with the HD group. These results suggest that the persimmon-vinegar has anti-obesity properties.     

Lumican,an Exerkine,Protects against Skeletal Muscle Loss

Exerkines are soluble factors secreted by exercised muscles, mimicking the effects of exercise in various organs, including the muscle itself. Lumican is reportedly secreted from muscles; however, its roles in skeletal muscle remain unknown. Herein, we found that lumican mRNA expression in the extensor digitorum longus was significantly higher in exercised mice than in unloading mice, and lumican stimulated myogenesis in vitro. Additionally, lumican knockdown significantly decreased muscle mass and cross-sectional area (CSA) of the muscle fiber in the gastrocnemius muscle of exercised mice. Lumican upregulated phosphorylation of p38 mitogen-activated protein kinase (MAPK) and a p38 inhibitor near completely blocked lumican-stimulated myogenesis. Inhibitors for integrin α2β1 and integrin ανβ3 also prevented lumican-stimulated myogenesis. Systemic lumican treatment, administered via the tail vein for 4 weeks, significantly increased relative muscle masses by 36.1% in ovariectomized mice. In addition, intramuscular lumican injection into unloaded muscles for 2 weeks significantly increased muscle mass by 8.5%. Both intravenous and intramuscular lumican treatment significantly increased muscle CSA. Our in vitro and in vivo experiments indicate that lumican is a muscle-secreted exerkine that affords protection against muscle loss by activating p38 MAPK via integrin receptors.     

Metastable Phases of Dross Particles Formed in a Molten Zinc Bath and Prediction of Soluble Aluminum During Galvannealing Processes

The morphology, chemistry, and crystallographic characteristics of metastable dross particles were identified. These particles are formed during the initial stage of precipitation. The particles had aluminum concentrations of 15 to 80 mass pct, with values that decreased gradually as particle size increased. These metastable dross particles were a mixture of the crystalline phase of FeZn₁₀, which is called the “delta phase,” and the high-aluminum amorphous phase, which covered the surface of the crystalline phase. The new “meta Q” concept was proposed to predict the amount of soluble aluminum in the zinc bath by considering nucleation kinetics and particle growth. The results calculated using the “meta Q” concept were compared with the values measured by the aluminum sensor, which were taken during the same period at the commercial galvanizing line. The mean of the absolute values of the differences between the calculated and measured values was 9.7 ppm.     

Improvement of the seismic safety of existing nuclear power plants by an increase of the component seismic capacity: A case study

This case study produces the scenario earthquakes for an example nuclear power plant (NPP) site and suggests the effective seismic capacity of safety-related equipment and components which significantly contribute to a core damage to improve the seismic safety of an existing NPP by using a probabilistic safety assessment. The response spectra for the scenario earthquakes show greater spectral accelerations than those for the design response spectrum in the frequency range higher than about 12 Hz. In order to improve the seismic safety of an example NPP, the effects of the seismic capacity of safety-related equipment and components on the core damage frequency (CDF) are investigated, and their effective seismic capacities are determined. The results of the case study show that an increase of the seismic capacity of the equipment reduces the CDF considerably. The effective seismic capacities for the diesel generator, offsite power, condensate storage tank and battery rack are determined as 0.84, 0.35, 0.63 and 0.63 g, respectively.     

A simplified framework for probabilistic earthquake loss estimation

Earthquake loss estimation procedures exhibit aleatory and epistemic uncertainty imbedded in their various components; i.e. seismic hazard, structural fragility, and inventory data. Since these uncertainties significantly affect decision-making, they have to be considered in loss estimation to inform decision- and policymakers and to ensure a balanced view of the various threats to which society may be subjected. This paper reviews the uncertainties that affect earthquake loss estimation and proposes a simple framework for probabilistic uncertainty assessment suitable for use after obtaining impact results from existing software, such as HAZUS-MH. To avoid the extensive calculations required for Monte Carlo simulation-based approaches, this study develops an approximate method for uncertainty propagation based on modifying the quantile arithmetic methodology, which allows for acceptable uncertainty estimates with limited computational effort. A verification example shows that the results by the approximation approach are in good agreement with the equivalent Monte Carlo simulation outcome. Finally, the paper demonstrates the proposed procedure for probabilistic loss assessment through a comparison with HAZUS-MH results. It is confirmed that the proposed procedure consistently gives reasonable estimates.     

Thermal characteristics of surface-crosslinked high density polyethylene beads as a thermal energy storage material

High density polyethylene (HDPE) beads were surface-crosslinked in a modified plasma reactor by using argon plasma. The modified plasma reactor can treat a large amount of beads to be uniformly surface-crosslinked. The objectives of this study were to develop a shape-stabilized functional thermal energy storage material and to find an optimum plasma reaction condition out of various operations. To achieve these objectives, we systematically studied the effects of the gas pressure, the radio frequency (RF) power and the treatment time on the degree of crosslinking. The degree of crosslinking was measured by solvent extraction method (BXM: boiling xylene method). The chemical and physical characterization of the material was performed by using fourier transform infra-red (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). Finally, we confirmed the thermal stability of surface-crosslinked HDPE through about 50 thermal cycling tests.     

Estimation of a state-dependent model parameter

A numerical algorithm was developed which estimates a state-dependent model parameter on the basis of transient state observation data. The algorithm was presented for the problem of estimating the temperature dependence of thermal diffusivity in a one-dimensional heat equation. The estimation problem was converted into a finite dimensional optimization problem by the least-squares formulation and B-splines representation of the parameter. Numerical experiments were performed using simulated observation data as well as the actual observation data obtained in a heat conduction experiment on rubber compound layers. The performance of the algorithm was discussed in relation to the effect of the parameter representation scheme, the quality and quantity of the data.