Broadband filters

Broadband data cannot be used to identify specific machine components (e.g., bearing, gears, etc.) or failure modes (e.g., imbalance, misalignment, etc.). The data acquired using broadband filters are limited to the total energy value contained within the user-selected frequency window or bandwidth, Fmin to Fmax-... 

Boto and Bunt [465] used thin-layer chromatography for the preliminary separation of chlorophylls and phaeophytins from seawater, and combined this with selective excitation fluorometry for the determination of the separated chlorophylls a, b, and c, and their corresponding phaeophytin components. An advantage of the latter technique is that appropriate selection of excitation and emission wavelengths reduces the overlap among the emission spectra of the various pigments to a greater extent than is possible with broadband excitation and the use of relatively broadband filters for emission. 

The measuring device is Robertson-Berger broadband filter UV radiometer (RB-biometer). The time series of 10 min sums obtained during August 1, 1996 to June 25, 1997 was supplemented by (i) daily averages of total ozone concentration measured by Dobson spectrophotometer in HK [17, 18], (ii) hourly totals of global solar radiation measured by a Kipp-Zonen CP-11 in HK, and hourly fractions of sunshine... 

The concept of a photo-release and report system has been realized with the 9-(2-methyl-l,3-dithien-2-yl)-9//-thioxanthen-9-ol tethered to a PAMAM dendrimer. Irradiation of the dendrimer system with a U-360 broadband filter results in cleavage of the dithienyl unit to generate, after hydrogen radical transfer, 2-methyl-l,3-dithiane and the tethered thioxanthone 630. The increased fluorescence of the latter confirms the successful photo cleavage. The system offers potential for the generation of high local concentrations of substituted dithianes in the vicinity of the dendrimer surface (Equation 209) <2005JA12458>. 

In UV and visible vapor, bubbles cannot be tolerated in the sample, because they will generate noise in the optical reading, and if a pressurized cell is used, the cell pressure must be kept constant. Nitrogen or water is used to purge the cell, and interference or broadband filters are used for checking calibration. Photometers are normally used for single-component mea-... 

A broadband filter transmitting light above 550 nm, but not in the range 400-500 nm. 

A broadband filter with an absorbance maximum near 450 nm is inserted into the optical path of the microscopy (before the cell sample), and the cells are adapted for 10 min to these light conditions. 

To measure the cellular response to a step-up in blue-light intensity, the broadband filter is rapidly removed (manually)... 

To measure the response to a step-down in light intensity, the same broadband filter can be rapidly inserted into the light beam. 

These are, in alphabetical order, ash-free filters, bandpass filters, black band filters, blue band filters, broadband filters, cigarette filter, fluted filters, high-pass filters, low-pass filters, qualitative filters, and quantitative filters. The filter is catholic. In German, in chemistry the filter has neutral gender. In communication theory, the filter has male gender, however. 

The total energy of all vibration components generated by a machine is reflected by broadband, or overall, amplitude measurements. The normal convention for expressing the frequency range of broadband energy is a filtered range between 10 to 10,000 Hz, or 600 to 600,000 cpm. Because most vibration-severity charts are based on this filtered broadband, caution should be exercised to ensure that collected data are consistent with the charts. 

The first method uses high-frequency vibration components that result from oscillating rotor bars. Typically, these frequencies are well above the normal maximum frequency used to establish the broadband signature. If this is the case, a high-pass filter such as high-frequency domain can be used to monitor the condition of the rotor bars. 

Constant speed frequency analysis Constant-speed machinery generates a relatively fixed set of frequency components within its signature. Therefore, specific APSs can be established to monitor using frequency analysis. Since speed is relatively constant, the location of specific frequency components (e.g., running speed) will not change greatly. Therefore, the broadband and each narrowband window can be established with a constant minimum and maximum frequency limit, which are referred to as fixed filters. 

Absolute-fault limits are typically based on industrial standards for specific classifications of machinery. Generally, these standards are based on a filtered broadband limit and are not adjusted for variables such as speed, load or mounting configuration. However, vibration amplitude and its severity depend on speed and load. Therefore, alert/alarm limits must be adjusted for variations in both of these critical factors. 

Most microprocessor-based vibration-monitoring systems acquire and record a filtered broadband energy level for... 

Most microprocessor-based systems permit composite trending (i.e., simultaneous displays) of both filtered broadband and narrowband data. Figure 44.28 illustrates... 

Data are peak values of velocity (ips) for a filtered broadband from 10 to 10,000 Hz. 

A clear understanding of the mode shape, or shaft deflection, of a machine s rotating element is a valuable diagnostic tool. Both broadband and narrowband filtered energy windows can be used at each measurement point and orientation across the machine. The resultant plots, one in the vertical plane and one in the horizontal plane, provide an approximation of the mode shape of the complete machine and its rotating element. 

The overall energy from the filtered broadband plotted against measurement location provides an approximation of the mode shape of the installed machine. Figure 44.31 illustrates a vertical broadband plot taken from a Spencer blower. Note that the motor appears to be flexing in the vertical direction. Extremely high amplitudes are present in the motor s outboard bearing and the amplitudes decrease at subsequent measurement points across the machine. 

The accepted severity limit for casing vibration is 0.628 ips-peak (velocity). This is an un-filtered broadband value and normally represents a bandwidth between 10 and 10,000 Hertz. This value can be used to establish the absolute fault or maximum vibration amplitude for broadband measurement on most plant machinery. The exception would be machines with running speeds below 1200 rpm or above 3600 rpm. 

UV irradiation of this bacterial cells using a broadband mercury-quartz lamp through an interference filter (bandwith 254 nm), provided preferential DNA damage with minimal effects on other subcellular structures. The exposure time ranged from 0 to 180 minutes in increments of 60 minutes, which gave total dose of UV exposure 1.21, 2.43 and 3.64 J/ m. ... 

For the central measurement, the field of view is rectangular (e.g., 0.3 by 1.25°) and for other eccentricities, the field is an annular arc similar to that provided in minimum motion photometry. The use of a CRT monitor introduces the same problem as the use of LEDs in HFP, namely, the broadband nature of the screen phosphors, and a correction must be made before reporting the peak MP optical density. A system that could employ lamps and filters instead of a CRT monitor would be difficult to design because of the complexity of the visual stimulus. 

Obviously, the one-step low-pass J filter produces the narrowest profile and is therefore the less efficient in removing direct correlations in HMBC spectra, while the five-step tuned low-pass J filter (f lps) offers the most broadband profile. For this filter, the intensity of the residual /ch signals remains below 0.11% for the range 125 < /ch < 225 Hz, which is remarkable. Interestingly, as long as the /ch couplings range of the molecule remains moderate (—60 Hz), the four- and five-step filters... 

Figure 27 Edited broadband HMBC spectrum of cyclosporine using the pulse sequences shown in Figure 26 in an interleaved manner. The two subspectra, CH + CH3 (left) and C + CH2 (right), exemplify the editing properties. The spectrum in the bottom displays the two subspectra, CH + CH3 (black) and C + CH2 (grey) in the same frame. The number of scans was 32 for each of the 128fi increments, the relaxation delay was 1 s, and the range for the third-order low-pass. /-filter was 115 Hz < Vch < 165 Hz. The spectra were processed to maintain the absorptive profiles in F, while a magnitude mode was done in F2.

---