Baseline Charts

Collect basic data around how long it will take to complete the major steps or substeps. Fill in any times or piece-count information in the relevant steps (e.g., 10 orders/hour). Write the estimated process cycle times on the bottom of the baseline chart. (Cycle time is how long a step spends on one unit, not including how long the unit is in a queue waiting for work to be performed.)... 

Forecast the wait times for any of the steps and insert on the baseline chart. 

Five different charts are presented in this chapter. The first has been arotmd since the beginning of the printed circuit industry and is intended for external traces. The second is for sizing internal traces. The third and fourth are for internal and external traces. These are from more recent studies and are referred to as baseline charts. The fifth is used with the baseline charts to account for the heat spreading and cooling effect when copper planes exist in the board. Even with these charts, there are times when charts alone do not offer enough information and analysis tools must be used to solve current carrying capacity problems. 

Baseline charts.These are additional charts for sizing conductors and show an example of the effect of variables that impact trace temperature rise when current is applied. (Additional baseline charts can be obtained from Thermal Man, Inc., that take into account FR-4, BT, copper planes, and board thicknesses of 0.038 to 0.059 in.) Further discussion follows regarding the significance of the copper weight or thickness, board material, board thickness, and copper planes ... 

Plane chart for a 1.78 mm thick polyimide PWB.This is a chart that describes the reduction in trace temperature rise as a function of the distance from a single copper plane.This chart is used with the internal and external baseline charts. 

If extrapolation is to be performed, use a baseline chart however, extrapolating the IPC charts is not recommended. 

Figure 16.10 represents estimates of temperature rise as a function of copper plane size and distance from trace to plane in a 0.07-in. (1.78 mm) thick polyimide board. The set of curves in Fig. 16.10 is used with the baseline charts, shown in Figs. 16.5 through 16.8. The first step is to calculate a delta T using the appropriate chart from Figs. 16.5 through 16.8. 

For groups of similar parallel conductors, if they are closely spaced (that is, as much as 25.4 mm [1.0 in.] spacing and less when using a baseline chart), the temperature rise may be found by using an eqnivalent cross-section and an equivalent current. The equivalent cross-section is equal to the sum of the cross-sections of the parallel conductors, and the equivalent current is the sum of the currents in the conductors. 

This technique acquires overall or broadband vibration readings from select points on a machine-train. This data is compared to either a baseline reading taken from a new machine or to vibration severity charts to determine the relative condition of the machine. Normally an unfiltered broadband measurement that provides the total vibration energy between 10 and 10,000 Hertz is used for this type of analysis. 

An example of an absorption spectrum—that of ethanol exposed to infrared radiation—is shown in Figure 12.12. The horizontal axis records the wavelength, and the vertical axis records the intensity of the various energy absorptions in percent transmittance. The baseline corresponding to 0% absorption (or 100% transmittance) runs along the top of the chart, so a downward spike means that energy absorption has occurred at that wavelength. 

Note that UV spectra differ from IR spectra in the way they are presented. For historical reasons, IR spectra are usually displayed so that the baseline corresponding to zero absorption runs across the top of the chart and a valley indicates an absorption, whereas UV spectra are displayed with the baseline at the bottom of the chart so that a peak indicates an absorption (Figure 14.13). 

During the preadministration assessment, the nurse reviews the patient s chart for the medical diagnosis and reason for administration of the prescribed drug. The nurse questions the patient regarding the type and intensity of symptoms (such as pain, discomfort, diarrhea, or constipation) to provide a baseline for evaluation of the effectiveness of drug therapy. 

When these drugs are given to the female patient with inoperable breast carcinoma, tire nurse evaluates the patient s current status (physical, emotional, and nutritional) carefully and records tire finding in tire patient s chart. Problem areas, such as pain, any limitation of motion, and the ability to participate in tire activities of daily living, are carefully evaluated and recorded in tiie patient s record. The nurse takes and records vital signs and weight. Baseline laboratory tests may include a complete blood count, hepatic function tests, serum electrolytes, and serum and urinary calcium levels. The nurse reviews these tests and notes any abnormalities. 

The detector was calibrated by pxm ing solutions of sodium dichromate of known absorbance through the sample port of the detector. The solutions were prepared in the carrier fluid which served as reference. The recorder response was measured as the ultimate height reached on the chart paper above the baseline when the sample fluid was switched to a sodiiam dichromate solution of known absorbance. The calibration was insensitive to flow-rate variations. 

Fig. 4.1a shows how resolution can be measured from a chromatogram. The values of V and w can be measured in volume, time or chart length (from the point of injection) as long as we use the same units for each of them. When two peaks are just resolved to the baseline, this corresponds to a resolution of 1.5. 

When the column is ready to be used, the chromatogram of a suitable test mixture should be obtained. The plate number and retention times of the test solutes should be noted, and the peaks should have a satisfactory shape (minimal tailing). For measurement of the plate number, the recorder should be used at a high chart speed. Fig. 5.1b(i) and (ii) show test chromatograms for a C-18 column prepared by the above method, and Fig. 5.1c and 5.Id show the data that you should report with the chromatogram. The retention for an unretained peak is taken as the small baseline disturbance just before the first peak. 

No. You do not need a stopwatch for the retention times. Find out the distance the chart paper crawls in, say, a minute. Then get out your little ruler and measure the distances from the starting point (either air peak or pen mark) to the midpoint of each peak on the baseline (Fig. 109). Dorl t be wise and do any funny angles. It won t help. You ve got the distances and the chart speed, so you ve got the retention time. It works out. Trust me. 

Go back and read about HPLC peak interpretation in the section on GC peak interpretation ( Sample on the Chart Recorder ). The analysis is exactly the same, retention times, peak areas, baselines,... all that. 

The TRAACS 800+ is controlled by a personal computer and the features provided include complete interactive control via keyboard or mouse calculation of results as necessary taking into account baseline or sensitivity drift, graphical output of calibration curves for all calibration types—either Hnear or non-hnear, input facility for sample identification data allowing storage on disc and real-time results together with chart traces on a computer printer. The programs allow easy access to input or data files and connection to other computers, and gives system performance verification to CLP standards and built-in QC charts. 

Calculation. Draw a baseline under all the peaks by connecting the baselines obtained at the start, between the tray changes, and at the end. Draw a standard curve using a chart reader (see Chapter 1, Chart reader ). If exactly 0.1000 g sample was taken, then divide the concentration corresponding to the sample peak, in pg N mk by 100 to give the % total N in DM. Multiply by 6.25 to obtain the % crude protein in DM (but see the exceptions in Discussion 7.7). 

Calculation. Draw a baseline on the chart under all the sample peaks by connecting the baseline from aspirating wash at the start, between trays and at the end. Read the concentration of the sample solutions by comparing the peak heights of the samples with the standards using a chart reader (see Chapter 1, Chart reader ). Divide the concentration in pg mb of soluble carbohydrate in the sample solution by 10 to get the % water soluble carbohydrate in the freeze-dried sample. Multiply by 100/(100 - % moisture) to give the percentage water soluble carbohydrate in the sample DM. 

When the baseline varies randomly over times similar to the peak width, it is called wander (Figure 5.2). Wander interferes most with interpreting a chart recording or the operation of an electronic integrator. It can come either from the detector or from extraneous sources, such as a small leak at a column fitting. 

Set the sensitivity in the UV monitor control unit to a suitable value that will enable peak detection at a given concentration of protein Zero the baseline or chart recorder. 

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