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--- refining_setting_weight_percents_directly [2011/08/25 07:46] – created alancoelho
+++ refining_setting_weight_percents_directly [2022/11/03 15:08] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+====== Refining/Setting Weight Percents directly ======
+==== Version 5 ====
+The macro Known_Weight_Percent can be used to either set a weight percent or to refine a weight percent. For example:
+   str...
+      ' scale parameter must not be defined for this phase
+      Known_Weight_Percent(10) ' set weight percent to 10
+To refine the weight percent then the following could be used:
+   str...
+      prm wt1 10 min 0 max 100
+      Known_Weight_Percent(wt1)
+Only one phase can have its weight percentage set by this macro. All remaining phases must have a scale factor.
+==== Version 4.1 ====
+Symbols used here are defined in the Technical Reference entry for [cell_mass !E] [cell_volume !E] [weight_percent !E]
+Ignoring the Brindley correction we can write
+   Sp = Q_sum  wp / (Mp Vp (1 – wp))
+where Qsum is Qp as written in the manual except that Sp Mp Vp is excluded.
+Thus if you had four phases and you knew the weight percents w1, w2, w3, w4 then you could write:
+   s1 = (s2 m2 + s3 m3 + s4 m4) w1 / (m1 (1 - w1))
+   s2 = (s1 m1 + s3 m3 + s4 m4) w2 / (m2 (1 - w2))
+   s3 = (s1 m1 + s2 m2 + s4 m4) w3 / (m3 (1 - w3))
+   s4 = (s1 m1 + s2 m2 + s3 m3) w4 / (m4 (1 - w4))
+where
+   m1 = M1 V1
+   m2 = M2 V2
+   m3 = M3 V3
+   m4 = M4 V4
+simplifying:
+   s1 = s2 m2 x1 + s3 m3 x1 + s4 m4 x1
+   s2 = s1 m1 x2 + s3 m3 x2 + s4 m4 x2
+   s3 = s1 m1 x3 + s2 m2 x3 + s4 m4 x3
+   s4 = s1 m1 x4 + s2 m2 x4 + s3 m3 x4
+where
+   x1 = w1 / (m1 (1 - w1))
+   x2 = w2 / (m2 (1 - w2))
+   x3 = w3 / (m3 (1 - w3))
+   x4 = w4 / (m4 (1 - w4))
+If you have need for up to 9 phases, please see [[refine_weight_percentage|this macro]] for help.
+We need to solve the four equations for three of the scale parameters. We will choose to solve for s1, s2 and s3.
+s4 will be refined.
+Substitute s2 into equation s1:
+   s1 = (s1 m1 x2 + s3 m3 x2 + s4 m4 x2) m2 x1 + s3 m3 x1 + s4 m4 x1
+or,
+   s1 = (s3 (m3 x2 m2 x1 + m3 x1) + s4 (m4 x2 m2 x1 + m4 x1)) / (1 - m1 x2 m2 x1)
+Let
+   t13 = (m3 x2 m2 x1 + m3 x1) / (1 - m1 x2 m2 x1)
+   t14 = (m4 x2 m2 x1 + m4 x1) / (1 - m1 x2 m2 x1)
+or,
+   s1 = s3 t13 + s4 t14
+Substitute s2 into equation s3:
+   s3 = s1 (m1 x3 + m1 x2 m2 x3) + s3 m3 x2 m2 x3 + s4 (m4 x2 m2 x3 + m4 x3)
+or,
+   s3 = (s1 (m1 x3 + m1 x2 m2 x3) + s4 (m4 x2 m2 x3 + m4 x3)) / (1 - m3 x2 m2 x3)
+Let
+   t31 = (m1 x3 + m1 x2 m2 x3) / (1 - m3 x2 m2 x3)
+   t34 = (m4 x2 m2 x3 + m4 x3) / (1 - m3 x2 m2 x3)
+or,
+   s3 = s1 t31 + s4 t34
+Substituting s1 into s3 we get:
+   s3 = s3 t13 t31 + s4 t14 t31 + s4 t34
+or,
+   s3 = s4 (t14 t31 + t34) / (1 - t13 t31)
+Then we set s4 to a starting refinement value and then calculate s1, s2 and s3 using the above equations, ie.
+   s3 = s4 (t14 t31 + t34) / (1 - t13 t31)
+   s1 = s3 t13 + s4 t14
+   s2 = s1 m1 x2 + s3 m3 x2 + s4 m4 x2
+Refining on s4 works well and the weight percents are kept to their known values. Similar equations can be written for three phases etc...
+Below is and INP file ZRO2-WT.INP (with data file ZRO2.DAT) that shows the above working nicely on Zro2. It uses the helper macro wt_dets  to hide some of the details. At the top of the file we see:
+<code topas>prm s4  0.01 min 1.0e-12  ' REFINABLE
+prm w1  5 min 1.0e-6	' Refine of fix depending on prior knowledge
+prm w2  2 min 1.0e-6	' Refine of fix depending on prior knowledge
+prm w3  2 min 1.0e-6	' Refine of fix depending on prior knowledge</code>
+If all of the weight percents were known then the three weight percents should be fixed to their known values.
+Here's the ZRO2-WT.INP
+<code topas>macro wt_dets(n)
+{
+   prm m##n = Get(cell_mass) Get(cell_volume);
+   prm x##n = w##n / (m##n (100 - w##n));
+   scale = s##n;
+}
+r_wp  0
+prm !t13 = (m3 x2 m2 x1 + x1 m3) / (1 - m1 x2 m2 x1);
+prm !t14 = (m4 x2 m2 x1 + x1 m4) / (1 - m1 x2 m2 x1);
+prm !t31 = (m1 x2 m2 x3 + x3 m1) / (1 - m3 x2 m2 x3);
+prm !t34 = (m4 x2 m2 x3 + x3 m4) / (1 - m3 x2 m2 x3);
+prm s1 = s3 t13 + s4 t14;
+prm s2 = s1 m1 x2 + s3 m3 x2 + s4 m4 x2;
+prm s3 = s4 (t14 t31 + t34) / (1 - t13 t31);
+prm s4  0.01 min 1.0e-12         ' REFINABLE
+prm w1  5 min 1.0e-6  ' Refine of fix depending on prior knowledge
+prm w2  2 min 1.0e-6  ' Refine of fix depending on prior knowledge
+prm w3  2 min 1.0e-6  ' Refine of fix depending on prior knowledge
+prm w4 = 100 - w1 - w2 - w3; : 0
+DAT(zro2)
+   CuKa2(0.001)
+   LP_Factor(17)
+   Radius(200.5)
+   Divergence(1)
+   Slit_Width(0.4)
+   Full_Axial_Model(12, 20, 12, 2.3, @ 10)
+   ZE(@, 0)
+   bkg @  0 0 0 0
+   STR(I_41/A_M_D:2, Zircon)
+      Tetragonal(6.6020, 5.97960)
+      site Zr    x 0   y =3/4;  z =1/8;    occ Zr 1   beq 1
+      site Si    x 0   y =1/4;  z =3/8;    occ Si 1   beq 1
+      site O     x 0   y 0.066  z 0.1951   occ O  1   beq 2
+      CS_L(500)
+      MVW( 733.228, 260.629261, 0.675`)
+      wt_dets(1)
+   STR(P_42/N_M_C_S, "Zr O2")
+      Tetragonal(@ 3.60, @ 5.17)
+      site Zr    x 0 y 0      z 0        occ Zr+4 0.95 beq 0.5
+                                         occ Y+3  0.05 beq 0.5
+      site O     x 0 y 0.5    z 0.20514  occ O-2   1   beq 1
+      Strain_L(@, .1)
+      Strain_G(@, .1)
+      MVW( 0, 0, 0)
+      wt_dets(2)
+   STR(F_M_-3_M, "Cubic Zirconia")
+      Cubic(@ 5.13)
+      site Zr    x 0        y 0      z 0        occ Zr 0.85  beq  1
+                                                occ Y  0.15  beq  1
+      site O     x 0.25     y 0.25   z 0.25     occ O  0.962 beq  2
+      Strain_G(@, .1)
+      MVW( 0, 0, 0)
+      wt_dets(3)
+   STR(R_-3_c, "Corundum Al2 O3")
+      Trigonal(@ 4.75, @  12.99)
+      site Al  x 0       y 0 z 0.35218 occ AL+3 1 beq  0.3366
+      site O   x 0.30665 y 0 z 0.25000 occ O-2  1 beq  0.3879
+      CS_L(500)
+      MVW( 0, 0, 0)
+      wt_dets(4)</code>
+ --- //[[alan.coelho@bigpond.com|Alan Coelho]] 2011/08/25 19:09//
+Weights can be restrained using:
+<code topas>'---------------------------
+'Example of restraining weight percent to a known value
+penalties_weighting_K1 .2
+restraint = (Cubic_Zirconia_wt_percent - 36); : 0
+'---------------------------</code>