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      <div class="title_topic3" id="xps10_pagetitle">Measurements notes</div>
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      <p class="para_topic"><a class="links" href="javascript:void(0)" onclick="top.openFile('quickstack/measurement.html');return(false);">Measurements</a> (or key characteristics) are the objects of interest in a tolerance analysis. You want to define the measurements whose values are subject to variations in the stack-up of component tolerances.
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      <p class="para_topic">The example below is a displacement pump. One of its functional requirements is to meet a certain pressure specification. A key element to producing this pressure is the relationship and clearance between the impellers. In this example, two of the critical design characteristics which should be measured in a tolerance analysis are the angle and distance between the impellers:</p>
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            <p class="para_item">If the angle is too far from the nominal angle of zero degrees, the nonuniform clearance gaps between the impellers will cause a loss of pressure. In this example, the designer believes that the angle can be between -0.5 and +0.5 degrees (i.e., the tolerance) without causing too much performance degradation. A Tolerance Stackup Validation (TSV) analysis will help determine the impact of this tolerance, and if the tolerance should be adjusted.</p>
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            <p class="para_item">If the distance between the impellers is too large, the correct pressure will not be produced. On the other hand, if the distance is too small, the impellers may collide with each other and cause part failure. The designer, therefore, should also define a tolerance for the distance, and then define the distance between impellers as a measurement for a TSV analysis.</p>
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      <div class="title_figure">Displacement Pump Example</div>
      <p class="para_topic">You can define as many measurements as you wish. The simulation will calculate the variation for all the specified measurements.</p>
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