diff --git a/numass-main/src/main/java/inr/numass/models/SterileNeutrinoSpectrum.java b/numass-main/src/main/java/inr/numass/models/SterileNeutrinoSpectrum.java
index 22018981..da7a49b9 100644
--- a/numass-main/src/main/java/inr/numass/models/SterileNeutrinoSpectrum.java
+++ b/numass-main/src/main/java/inr/numass/models/SterileNeutrinoSpectrum.java
@@ -8,34 +8,85 @@ package inr.numass.models;
 import hep.dataforge.functions.AbstractParametricFunction;
 import hep.dataforge.functions.ParametricFunction;
 import hep.dataforge.values.NamedValueSet;
+import inr.numass.NumassContext;
+import org.apache.commons.math3.analysis.BivariateFunction;
+import org.apache.commons.math3.analysis.UnivariateFunction;
 
 /**
- *
+ * Compact all-in-one model for sterile neutrino spectrum
  * @author Alexander Nozik
  */
 public class SterileNeutrinoSpectrum extends AbstractParametricFunction {
- 
+
     private static final String[] list = {"X", "trap", "E0", "mnu2", "msterile2", "U2"};
-    private ParametricFunction spectrum;
+    BetaSpectrum source;
 
     public SterileNeutrinoSpectrum() {
         super(list);
     }
-    
+
+    /**
+     * Transmission function including detector backscattering
+     *
+     * @param u
+     * @param set
+     * @return
+     */
+    private BivariateFunction transmission(double u, NamedValueSet set) {
+
+    }
+
+    /**
+     * Loss function excluding trapping
+     *
+     * @param u
+     * @param set
+     * @return
+     */
+    private BivariateFunction loss(double u, NamedValueSet set) {
+
+    }
+
+    /**
+     * Trapping spectrum
+     *
+     * @param u
+     * @param set
+     * @return
+     */
+    private BivariateFunction trapping(double u, NamedValueSet set) {
+
+    }
+
+    /**
+     * Source spectrum including final states
+     *
+     * @return
+     */
+    private ParametricFunction source() {
+        return source;
+    }
+
+    private BivariateFunction convolute(BivariateFunction loss, BivariateFunction resolution) {
+        return (eIn, u) -> {
+            UnivariateFunction integrand = (double eOut) -> loss.value(eIn, eOut) * resolution.value(eOut, u);
+            return NumassContext.defaultIntegrator.integrate(integrand, u, eIn);
+        };
+    }
 
     @Override
-    public double derivValue(String parName, double x, NamedValueSet set) {
+    public double derivValue(String parName, double u, NamedValueSet set) {
         throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
     }
 
     @Override
-    public double value(double x, NamedValueSet set) {
-        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
+    public double value(double u, NamedValueSet set) {
+
     }
 
     @Override
     public boolean providesDeriv(String name) {
         throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
     }
-    
+
 }