Test response spectrum

A sinusoidal or sinusoidal beat motion can be used for the qualification testing of stiff systems at a frequency significantly lower than the first mode frequency of the system. This should result in a test response spectrum that envelops the reference response spectrum required to qualify the item. If no adequate shaking device is available, a sinusoidal motion can be used at resonance to obtain the necessary quahfying level of response of the item. 

Active relays shall be tested using a test response spectrum which envelops the FRS developed for RP and increased to account for the mounting structure on equipment and amplification, if any. 

This is the response spectrum, constructed for a particular location, for a future earthquake. It is based on seismic studies conducted for that region and past seismic records of and around that region, if available. It forms the basic parameters for the design and testing of an object. 

Floor acceleration This is the time history of acceleration of a partictilar floor nr structure caused by a given ground acceleration (Figure 14.16). It may have an amplified narrow band spectrum due to structural filtration, where single frequency excitation and resonance may predominate, depending upon the dynamic characteristics of the structure. A floor response spectrum (FR.S). as shown in Figure 14.18, can be derived from this history. Consideration of GRS or FRS will depend upon the location of the object under test. 

This is a response spectrum obtained during a test in a laboratory while exciting the shake table with ground movements as in the RRS. The test object is mounted on the shake table. The test object should respond normally during such movements. The test conditions (i.e. TRS) should closely overlap the required seismic conditions (i.e. RRS) of Figure 14.25. 

This is the duration sufficient to simulate seismic conditions. It depends upon the algorithm used to find time history from the reqtiired response spectrum (RRS). The minimum duration of a strong movement, as recommended by IEEE 344, is 15 seconds as illustrated in Figure 14.24(b). This will require a total duration of the order of 20 seconds, including the movement s times of rise and time of decay. A duration of 20.48 seconds, as noted in the figure, is typical of a test conducted at University of Rorkee. The following tests may be conducted ... 

Short-term tests. Tests for point mutations, numerical and structural chromosome aberrations, DNA damage/repair, and in vitro transformation provide supportive evidence of stochastic responses and may give information on potential mechanisms of action. A range of tests for each of the above responses helps to characterize the response spectrum of a substance. 

These tests are standardized (e.g. see USNRC, 1988). These standards require that a component is placed on a vibrating table and that it is submitted to a higher vibratory load than that characterized by the floor response spectrum. In some cases, if necessary, the component is even verified for operation during the test. The components are tested together with their support structure to avoid a further uncertainty in the calculation of the dynamic load at the level where they are located. The excitation must include all three axes, unless S5unmetry conditions exist. 

When the system has one or more vibrational resonances in the frequency range of interest, the test input motion should have a response spectrum not smaller than the required design basis response spectrum. This can be achieved... 

When the natural frequencies of the item are well separated, independent tests can be made, for example with a suitably scaled sinusoidal input at the given frequenqr with a half-sine or other time envelope of interest. However, such tests should be made with two or more time histories or natural time histories whose response spectra are not lower than the required design basis response spectrum. The use of several different time histories helps to overcome any deficiencies that could arise from the peculiarities of a single time history. 

Bellinger and Needleman (2003) reanalyzed their earlier cohort data, specifically stratifying the outcomes of the psychometric tests and dose—response strengths for 24-month PbB levels into those <10 pg/dl (N = 48) and those S 10 pg/dl. These authors reported that the dose—response slope, IQ loss versus PbB increase, was threefold steeper at PbB <10 pg/dl than for blood Pb values at 10 units or higher. This curvilinear relationship across the dose—response spectrum at lower versus higher dose has been documented in other individual and aggregated studies noted below. 

The methods used to show acceptability of outliers shall be identified. The acceptable methods include response spectrum analysis, equivalent static analysis, or testing. 

Promoting Optimal Response to Therapy The results of a culture and sensitivity test take several days because time must be allowed for the bacteria to grow on the culture media However, infections are treated as soon as possible In a few instances, the primary health care provider may determine that a penicillin is the treatment of choice until the results of the culture and sensitivity tests are known. In many instances, the primary health care provider selects a broad-spectrum antibiotic (ie, an antibiotic that is effective against many types or strains of bacteria) for initial treatment because of the many penicillin-resistant strains of microorganisms. 

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