Fragility, definition

It should be noted that there are ways for compensating the limitation of PGA as a unique descriptor of a seismic event, either on the hazard definition - relying on notions such as the intensity or cumulative absolute velocity (CAV refer to EPRI (2006), Campbell and Bozorgnia (2011)) in the hazard curve development - or on the structural response (—>spectral shape factor in the fragility definition below). 

It is useful to express the fragility in terms of a random variable representing the capacity, denoted by /I, and defined in terms of the same ground motion parameter used for the fragility definition. Obviously, failure occurs if the capacity is lower than the peak ground acceleration of the assumed seismic event. The definition of the fragility can then be extended as follows ... 

First, consider uniaxial tension loading in the 1-direction on a flat piece of unidirectionally reinforced lamina where only the gage section is shown in Figure 2-20. The specimen thickness is not just one lamina, but several laminae all of which are at the same orientation (a single lamina would be too fragile to handle). The strains and E2 are measured so, by definition,... 

The definition of osteoporosis is (NIH 2000) A systemic skeletal disease characterized by low bone mass and micro architectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture . 

To measure the departure from an Arrhenius-like behavior and to decrease the ambiguity in the use of fragility as a quantitative probe of the liquid state, the so-called F1/2 metric has been introduced. It is defined as the value of Tg/T at the midway of the relaxation time on a log scale, specifically, between the high-temperature phonon vibration lifetimes 10 14 s and the relaxation time at Tg, namely, i Tg), which is generally taken to be 102s [37], An advantage of this definition is that the midway values for the relaxation time are readily and accurately accessible by viscosimetric and by dielectric measurements [37,43], Let T /2 be temperature at which x = 10 6s. Now define a quantity Fx /2 as follows [37,43] ... 

Note that the magnitude of Fj/2 lies between zero and unity. The quantity Fj/2 is a measure of the fragility of the supercooled liquid. The Fj/2 fragility metric has two notable virtues (1) it is independent of the fitting function employed to analyze the experimental data [37,43] and (2), because of the definition of the midway temperature, the relaxation time at this characteristic temperature is accurately accessible by various experimental techniques [37,43],... 

An alternative and perhaps more accurate definition of thermodynamic fragility that can be determined experimentally for almost all liquids would be to determine the fraction of entropy of fusion lost by T/Tm = 0.8 [37,88]. In both the definitions, the property of the crystal phase enters this disadvantage is missing in the kinetic measures of fragility [37,88]. 

In parallel with Eq. (2.12), the E 3/ 4 tllermo metric is defined as the value of ( Tg/T) for which Sexc(Tg)/Sexc(T) With this definition, a correlation was observed between kinetic F1/2 and thermodynamic F3/2 thermo fragilities [38]. 

The inheritance pattern of fragile X syndrome is unusual. While about 80% of males who inherit the mutation exhibit mental retardation and a more or less definitive phenotype, the remaining 20% of carrier males are pheno-typically normal. Such clinically normal hemizy-gous males are termed transmitting males because the mutation is transmitted through their unaffected daughters to grandchildren,... 

Most modern papers have a reasonable life expectancy of about 50 years. Permanent paper is paper that can have a reasonable life expectancy exceeding 200 years. The important phrase in this definition is reasonable life expectancy. Permanent paper is still a fragile commodity, and the papermaker has no control over paper processors and ultimate users or abusers. 

By definition, brazes have a different composition from the components they are used to join and hence interdiffusion will occur during and after interface creation. Reference has been made already to the detrimental effects of the growth of thick reaction products at metal-ceramic interfaces and similar effects can occur with metal-metal systems. Thus it is not good practice to use A1 brazes for the joining of steel or Cu components or to use Ni brazes containing Si for the joining of refractory metal components because of the rapid formation of fragile layers of intermetallic compounds. 

The migration of moisture will be accompanied by the migration of water-soluble salts, which may lead to hydration-rehydration cycles over much wider areas. All these processes definitely weaken this already fragile tomb and will lead to its further degradation. Therefore, traditional methods must clearly be reevaluated in the development of a conservation scheme for this site. 

The results are shown in Fig. 3.5. According to Fig. 3.5b, mechanochemical yield per unit of consumed energy appeared to be a constant only starting from some threshold power per 1 g of the mixture under treatment. This threshold is about 5 W/g. The existence of threshold effect in solids is connected with fragile-viscous transition the latter occurs only when a definite level of energy input to a solid is exceeded. 

The open FFF channel is especially suited to fragile materials, and thermal FFF has found a definite niche in its application to ultrahigh-molecular-weight polymers. Furthermore, because samples need not be filtered, thermal FFF is the technique of choice for analyzing gels, rubbers, and other materials that tend to plug SEC columns [7]. Even particles can be analyzed... 

An estimated 75 million people are affected by osteoporosis to some degree in the United States, Europe, and Japan. Osteoporosis is a systematic skeletal disease characterized by bone mass and microarchitectural deterioration with a consequent increase in bone fragility and susceptibility to fracture. Operationally, osteoporosis can be defined as a certain level of bone mineral density. The definition of osteoporosis is somewhat arbitrary and is based on epidemiological data relating fracture incidence to bone mass. Uncertainty also is introduced due to variability in bone densitometry measurements. Other clinical measures to assess the skeleton include collagen cross-links (measure of bone resorption) and levels of bone-specific alkaline phosphatase and osteocalcin (bone formation). A list of biochemical markers of bone remodeling is provided in Table 37-3. Measurement of total serum alkaline phosphatase level and urinary hydroxyproline or calcium levels is of limited value. 

Figure 5 shows this plot for 3 different binary mixtures, as well as for a neat system (the epoxy resin PPGE). A good superposition for the a-relaxation frequency is obtained, as it is expected, since the steepness index of Za(T) m (fragility according to Angell definition ) is almost constant under pressure... 

In the opinion of the authors the improved definitions should be used also for the volume-related and density-related fragility metrics, namely ... 

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