Temperature sweep

Before relighting a hot furnaee that burns fuel oil with a flash point above ambient temperature, sweep it out for a period of time, long enough to make sure that any unburnt oil has evaporated. If this eauses too mueh delay, then pilot burners supplied by an alternative supply should be kept alight at all times. 

The order in PA can be studied by WAXS and SAXS. WAXS gives insights into the unit cell sttucture, the crystallinity, the crystallite size (if not too large), and the crystallite orientation. SAXS gives a more accurate measure of the lamella thickness. In a temperature sweep, the changes in structure with temperature can be followed. 

The strain temperature sweep measurement is conducted with a preselected amplitude for the applied strain (y) and a constant frequency (f). The changing parameter is the temperature T, which is given in a temperature-time profile [T = T(t)]. This test method serves to illuminate the structural build-up, the softening, the melting and the gelation of pectins influenced when the temperature changes. 

Rheological Properties Measurements. The viscoelastic behavior of the UHMWPE gel-like systems was studied using the Rheometric Mechanical Spectrometer (RMS 705). A cone and plate fixture (radius 1.25 cm cone angle 9.85 x 10" radian) was used for the dynamic frequency sweep, and the steady state shear rate sweep measurements. In order to minimize the error caused by gap thickness change during the temperature sweep, the parallel plates fixture (radius 1.25 cm gap 1.5 mm) was used for the dynamic temperature sweep measurements. 

Monts CwtoAVorstCase Parametic Sweep Temperature (Sweep) Save Bias Point load Bias Point... 

The Temperature (Sweep) allows us to specify a single temperature or a list of temperatures. If you specify a list of temperatures, the simulation will be run several times, once for each temperature you place in the list. We only need to run the simulation once, so fill in the dialog box as shown ... 

We have specified the simulation to run at 100°C. The simulation of the previous simulation did not specify a temperature and the simulation ran at the default temperature of 25°C. Notice in the screen capture above that there is a checkmark El in the box next to the Temperature (Sweep) option. The temperature sweep will not run if this box is not checked. The option above specifies that the Bias Point simulation will run at 100°C. Click the OK button to return to OrCAD Capture. 

In general, we can run the temperature sweep as either a Parametric Sweep or a Secondary Sweep. However, to generate I-V characteristic curves for different temperatures, we must use the Secondary Sweep. Click on the square D next to the Secondary Sweep selection ... 

We will set up a temperature sweep from -25°C to +125°C. Select PSpice and then New Simulation Profile from the Capture menus, specify a name for the profile, and then click the Create button. Select the DC Sweep Analysis type and fill in the dialog box as shown ... 

We will now run the same temperature sweep that we did in the previous section. Plot IC(Q1) and use the cursors to label the values at the end points of the trace. 

We will now run a linear temperature sweep from -25 to 125°C to see how this circuit is affected by temperature. For the first simulation only the BJT will have temperature dependence. We will use normal resistors (part name R), which are independent of temperature. Note that the Q2n3906 BJT model includes temperature dependence. Set up the DC Sweep as shown ... 

A temperature sweep can be used in conjunction with most of the analyses. Here we will show how temperature affects the performance of a linear voltage regulator. Create the circuit shown below ... 

Click the LEFT mouse button on the square Cl next to the text Temperature (Sweep) to enable the sweep and display the options for the sweep ... 

The checkmark in the square El indicates that the sweep is enabled. Note that both the Temperature (Sweep) and the Time Domain analysis are enabled. Fill in the Temperdture (Sweep) parameters as shown ... 

Click the OK button and then run the simulation. It will take three times as long as the previous simulation because the Transient Analysis will run three times. Logically, the Transient Analysis runs inside the Temperature Sweep. For this example, the temperature will be set to -25°C, and then the Transient Analysis will be run. Next, the temperature will be set to 25°C, and then the Transient Analysis will be run. Finally, the temperature will be set to 125°C, and then the Transient Analysis will be run. 

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