Equivalent spectrum method

A key element of PEM fuel cell is the CCL, which contains a double layer capacitance connected to resistivities due to proton and oxygen transport. To understand measured CCL spectra, many works employ the equivalent circuit method (ECM). This method is based on the construction of an equivalent transmission line, which gives an EIS spectrum close to the spectrum of the system of interest. The components of the resulting circuit are then attributed to CL physical parameters. For example, in a recent work, Nara et al. (2011) used the ECM to study the CCL degradation mechanisms in the PEFC. 

If the secant stiffness is used to define the properties of the equivalent SDOF oscillator, typically the overdamped acceleration spectra are used (see Fig. 4d). Actually the capacity spectrum method approach is followed. It is explained later in section ATC-40 where the method included into the ATC-40 is presented. 

While several similarities can be found between the EC8/3 and FEMA-356, the simplified nonlinear procedure in ATC-40 is rather different. It is based on the equivalent linearization. This is a version of the capacity spectrum method, which was first introduced by Freeman et al. (1975). The basic assumption is that the maximum displacement of the nonlinear SDOF system can be estimated from the maximum displacement of a linear elastic SDOF system that has the period and damping ratios that are larger than those of the initial values for the nonlinear system. The elastic SDOF system that is used to estimate the maximum inelastic displacements of the nonlinear system is usually referred to as the equivalent or the substitute system. The period and damping of the equivalent system are referred to as the equivalent period and equivalent damping ratio, respectively. 

The capacity spectrum method of equivalent linearization assumes that the equivalent damping of the system is proportional to the area enclosed by the capacity curve. The equivalent period, Tgq, is assumed to be the secant period at which the seismic ground motion demands, reduced by the equivalent damping, intersect the capacity curve (FEMA-440). Since the equivalent period and damping are both a function of the displacement, the solution to determine the maximum inelastic displacement (i.e., performance point) is iterative. 

Mechanical-based models for territorial scale analysis on classes of buildings can be defined on the basis of either traditional force-based procedures (e.g., capacity spectrum method implemented in HAZUS, in NIBS (2003), or in RISK-UE (2004)) or according to displacement-based designed approaches (e.g., Calvi et al. 2005). According to force-based procedures, the buUding performance is identified, within acceleration-displacement response spectra (ADRS) by the intersection point between the capacity curve of an equivalent nonlinear SDOF... 

Design method Simplified spectrum method Uses the fundamental mode of oscillation and looks at equivalent seismic forces. Simplified and does not take into account so many complexities, just using base shear multiplied by the design spectra value and distributing the lateral forces over the height of the building 5... 

Regarding the method of analysis, according to ASCE/AWEA RP2011 a fully coupled time-domain analysis and decoupled analyses based on equivalent lateral force method or modal response spectrum method are acceptable, as permitted by the local building code. For the specific implementation of each method of analysis, the local building code or ASCE/SEl 7-05 is referred to. In particular, if the equivalent lateral force procedure is used, the vertical distribution of seismic forces should be calculated based on the procedure given in ASCE/SEl 7-05,... 

Objective Evaluation of Color. In recent years a method has been devised and internationally adopted (International Commission on Illumination, I.C.I.) that makes possible objective specification of color in terms of equivalent stimuli. It provides a common language for description of the color of an object illuminated by a standard illuminant and viewed by a standard observer (H). Reflectance spectro-photometric curves, such as those described above, provide the necessary data. The results are expressed in one of two systems the tristimulus system in which the equivalent stimulus is a mixture of three standard primaries, or the heterogeneous-homogeneous system in which the equivalent stimulus is a mixture of light from a standard heterogeneous illuminant and a pure spectrum color (dominant wave-length-purity system). These systems provide a means of expressing the objective time-constant spectrophotometric results in numerical form, more suitable for tabulation and correlation studies. In the application to food work, the necessary experimental data have been obtained with spectrophotometers or certain photoelectric colorimeters. 

Erk [20] described a spectrophotometric method for the simultaneous determination of metronidazole and miconazole nitrate in ovules. Five capsules were melted together in a steam bath, the product was cooled and weighed, and the equivalent of one capsule was dissolved to 100 mL in methanol this solution was then diluted 500-fold with methanol. In the first method, the two drugs were determined from their measure d%/dk values at 328.6 and 230.8 nm, respectively, in the first derivative spectrum. The calibration graphs were linear for 6.2—17.5 pg/mL of metronidazole and 0.7—13.5 pg/mL of miconazole nitrate. In the second (absorbance ratio) method, the absorbance was measured at 310.4 nm for metronidazole, at 272 nm for miconazole nitrate and at 280.6 nm (isoabsorptive point). The calibration graphs were linear over the same ranges as in the first method. 

This information is plotted by the computer in alternative ways and it is important for the analyst to be aware of the ways in which the data system is operating. In the normalized or percentage relative abundance (%RA) method, which is commonly used, the height of each peak is shown as a percentage of the biggest peak in the spectrum. The total ion current (TIC) is the sum of all the detector responses for each scan plotted against time and this is equivalent to a GLC trace. This information is particularly useful in quantitative analysis. 

Mention should be made here of recent attempts by Piepho, Schatz and Krausz (46) to give a general interpretation of intervalence bandshapes in terms of a Hamiltonian equivalent to that of eq 6. They use vibronic eigenfunctions (following the method of solution of Merrifield (47)) rather than adiabatic Born-Oppenheimer (ABO) functions. Thus, the aim is to interpret an observed spectrum in terms of one vibrational coupling mode, which is antisymmetric. Their analysis of the spectrum of the Creutz-Taube ion yields a value of 0 of 1.215, i.e., a rather weakly localized ground state. Using their assumed unperturbed... 

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