PsdCorrection.java

  1. /* Copyright 2002-2024 Thales Alenia Space
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.models.earth.displacement;

  19. import org.hipparchus.geometry.euclidean.threed.Vector3D;
  20. import org.hipparchus.util.FastMath;
  21. import org.orekit.bodies.GeodeticPoint;
  22. import org.orekit.time.AbsoluteDate;

  24. /** Model for post-seismic deformation corrections.
  25.  * @since 12.1
  26.  * @author Luc Maisonobe
  27.  */
  28. public class PsdCorrection {

  30.     /** Correction axis. */
  31.     private final Axis axis;

  33.     /** Time evolution. */
  34.     private final TimeEvolution evolution;

  36.     /** Earthquake date. */
  37.     private final AbsoluteDate earthquakeDate;

  39.     /** Amplitude. */
  40.     private final double amplitude;

  42.     /** Relaxation time. */
  43.     private final double relaxationTime;

  45.     /** Simple constructor.
  46.      * @param axis correction axis
  47.      * @param evolution time evolution
  48.      * @param earthquakeDate earthquake date
  49.      * @param amplitude amplitude
  50.      * @param relaxationTime relaxation time
  51.      */
  52.     public PsdCorrection(final Axis axis,
  53.                          final TimeEvolution evolution,
  54.                          final AbsoluteDate earthquakeDate,
  55.                          final double amplitude,
  56.                          final double relaxationTime) {
  57.         this.axis           = axis;
  58.         this.evolution      = evolution;
  59.         this.earthquakeDate = earthquakeDate;
  60.         this.amplitude      = amplitude;
  61.         this.relaxationTime = relaxationTime;
  62.     }

  64.     /** Get correction axis.
  65.      * @return correction axis
  66.      */
  67.     public Axis getAxis() {
  68.         return axis;
  69.     }

  71.     /** Get time evolution.
  72.      * @return time evolution
  73.      */
  74.     public TimeEvolution getEvolution() {
  75.         return evolution;
  76.     }

  78.     /** Get earthquake date.
  79.      * @return earthquake date
  80.      */
  81.     public AbsoluteDate getEarthquakeDate() {
  82.         return earthquakeDate;
  83.     }

  85.     /** Get amplitude.
  86.      * @return amplitude
  87.      */
  88.     public double getAmplitude() {
  89.         return amplitude;
  90.     }

  92.     /** Get relaxation time.
  93.      * @return relaxation time
  94.      */
  95.     public double getRelaxationTime() {
  96.         return relaxationTime;
  97.     }

  99.     /** Compute displacement.
  100.      * @param date date
  101.      * @param base base point
  102.      * @return displacement vector in Earth frame
  103.      */
  104.     public Vector3D displacement(final AbsoluteDate date, final GeodeticPoint base) {
  105.         final double scaledTime = date.durationFrom(earthquakeDate) / relaxationTime;
  106.         final double timeFactor = evolution.timeFactor(scaledTime);
  107.         return new Vector3D(amplitude * timeFactor, axis.vector(base));
  108.     }

  110.     /** Enumerate for correction axis. */
  111.     public enum Axis {
  112.         /** East axis. */
  113.         EAST {
  114.             public Vector3D vector(final GeodeticPoint base) {
  115.                 return base.getEast();
  116.             }
  117.         },

  119.         /** North axis. */
  120.         NORTH {
  121.             public Vector3D vector(final GeodeticPoint base) {
  122.                 return base.getNorth();
  123.             }
  124.         },

  126.         /** Up axis. */
  127.         UP {
  128.             public Vector3D vector(final GeodeticPoint base) {
  129.                 return base.getZenith();
  130.             }
  131.         };

  133.         /** Get axis unit vector.
  134.          * @param base base point
  135.          * @return direction in Earth frame
  136.          */
  137.         public abstract Vector3D vector(GeodeticPoint base);
  138.     }

  140.     /** Enumerate for correction time evolution. */
  141.     public enum TimeEvolution {

  143.         /** Exponential evolution. */
  144.         EXP {
  145.             public double timeFactor(final double scaledTime) {
  146.                 return 1 - FastMath.exp(-scaledTime);
  147.             }
  148.         },

  150.         /** Logarithmic evolution. */
  151.         LOG {
  152.             public double timeFactor(final double scaledTime) {
  153.                 return FastMath.log(1 + scaledTime);
  154.             }
  155.         };

  157.         /** Evaluate correction time factor.
  158.          * @param scaledTime scaled time since earthquake
  159.          * @return correction time factor
  160.          */
  161.         public abstract double timeFactor(double scaledTime);

  163.     }

  165. }
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