Tuesday, April 10, 2012

Release version 1.2.6 of Tonatiuh

Tonatiuh release 1.2.6 is now available from the main Tonatiuh website. This new version of the program includes new features that facilitates:

  • The modeling of heliostats fields and, thereby, the modeling of solar tower systems;
  • The testing of different atmospheric transmittance models;
  • The ray casting process, allowing the user to select the objects that should be taken into account during the process.

These new features are:

  • A new wizard-type plug-in that facilitates the simulation of solar tower systems. The wizard generates a heliostat field taking as input from the user: (1) a text file with the coordinates of the center of the bases of the heliostats that compose the heliostat field and (2) a component Tonatiuh file describing the geometry of the heliostats (it is assumed that the geometry of all heliostats are the same).
  • Several new atmospheric transmittance plug-ins.
  • A new reflectance material plug-in, which allows the user to independently define the slope error and the reflectivity ray error of a mirror-like surface.
  • The possibility for the user of selecting which of the surfaces in the scene should not be taking into account during the ray tracing process.
  • The resolution of a bug that made the program crash when the user tries to "undo" the elimination of a One-Axis tracker.
  • The resolution of a bug associated with the definition of the Sun position using the SunPositionCalculator? window (the error is related to an incorrect conversion from degrees to radians).

During the coming weeks we will be developing tutorials showing how to use this new features, and we will be posting them in the tutorials section of the Tonatiuh website.

Thanks for using Tonatiuh and for supporting its development with your comments, suggestions, and questions.

Wednesday, January 18, 2012

Release version 1.2.4 of Tonatiuh


Tonatiuh release 1.2.4 is now available. This new version of Tonatiuh is another minor release of the program. It incorporates the following features:

  • The scripting capabilities have been increased to the point that in this new release of the program any operation and functionality available to the users via the Graphics User Interface is now also available via scripting.
  • The resolution of a bug that produced the unexpected closing of the program when the user tries to cast rays before creating the concentrating geometry.
  • The resolution of a bug associated with storing a given Tonatiuh "scene" under very particular and uncommon conditions.
As in previous releases we are providing 32 and 64-bit installers of this new release of the program for the three major operating systems: Windows, Linux, and Mac. The installer for the Maxc OS is the same for both the 32 and 64 version of the program. While we have been able to test the 64-bit version of Tonatiuh release 1.2.4 for Windows 7 and Linux, we have not tested the 64-bit version of Tonatiuh for the Mac OS. Thus, please, let us know how it works for you.

In February 20 we expect to release the next version of the program. Please, let us know your suggestions for the new functionality you would like to see incorporated in the program.

Saturday, December 17, 2011

Release version 1.2.3 of Tonatiuh


Tonatiuh release 1.2.3 is now available. This new version of Tonatiuh is a minor release of the program. It incorporates the following features:
  • The option to specify the transmissivity of the media in which the concentrating system is immersed.
  • An optimized ray generation algorithm, that analyzes the concentrating geometry as seen from the ray casting surface (usually a plane perpendicular to the main direction of the direct solar radiation) and determines the areas of the overall ray casting surface from which to actually cast rays.
  • An improved version of the Buie's Sunshape plug-in.
  • Updated Marble's maps that improve the selection of the plant location and the solar time by the user.
The test carried out so far allow us to conclude that this new version of Tonatiuh is more stable and fast than all previous ones.

Thursday, September 29, 2011

Release version 1.2.2 of Tonatiuh


We just released version 1.2.2 of Tonatiuh. This new release of Tonatiuh is another minor release of the program. It solvers a series of minor bugs of the program, and the following major ones:  

  • The inappropriate sizing of the ray casting surface. In the previous release of Tonatiuh when the user modified the concentrating geometry, adding or substracting surfaces, the ray casting surface was not resized accordingly. This behavior has been corrected in the present release, so that the size of the ray casting surface is always adjusted to the concentrating geometry in order to increase the probabilities that the rays that are cast hit the concentrating geometry, decreasing the time needed to converge to accurate estimate of variables which are of interest to the user, such as the total power on target, the flux distribution in a given surface, etc.

  • The erroneous generation of the seven-tuples of the photon map. In the previous release of the program, the field of the seven-tuple of a given photon that was associated with the side of the surface that the photon was hitting was incorrectly always set to -1, instead of setting it to 0 if the photon was hitting the rear side of the surface or to 1 if it was hitting the front side of the surface. This has been corrected in the present release of the program.

  • The undesired possibility for the user of being able to associate a tracker to a TShapeKit. In the previous release of the program the user could select a TShapeKit and then include within it a Tracker element, with the operation resulting in a program crash, since Tracker elements are only intended to be use as child of TSeparatorKit elements. In the present release of the program, the program behavior has been modified to guarantee that the user can only associate a Tracker to a TSeparatorKit.

  • The incapacity of the program to open Tonatiuh files containing TShapKit nodes that do not have associated a TShape node. In the previous release of the program, if the user closed a Tonatiuh session having defined a TShapeKit node without associating to it a valid TShape node as a child, the program was not able to subsequently open the given Tonatiuh file any more. The present release correct this.
  • The crash of Tonatiuh when the user aborted the operation of creating a Bezier patches TShape node. In the previous release of the program, when a user was defining a Bezier patches TShape node, if she or he was in the process of entering the path to the data file containing the geometric information to create the Bezier patches and decided to abort that operation Tonatiuh crashed. The present release correct this error, and when the user aborts the entering of the geometry data filename, the program just do not create the Bezier patches TShape node.
As a result of correcting all the mentioned bugs, we hope that this new release of Tonatiuh will be a much more stable version of the program than previous ones. 

As promised, we are providing 32 and 64-bit installers of this new release of the program for the three major operating systems: Windows, Linux, and Mac. The installer for the Maxc OS is the same for both the 32 and 64 version of the program. While we have been able to test the 64-bit version of Tonatiuh release 1.2.2 for Windows 7 and Linux, we have not tested the 64-bit version of Tonatiuh for the Mac OS. Thus, please, let us know how it work for you.

In October 23 we expect to release the next version of the program. Please, let us know your suggestions for the new functionality you would like to see incorporated in the program.

Monday, September 12, 2011

The size of the focal spot of an ideal parabolic dish solar concentrator

Tonatiuh can be used to explore diverse aspects of solar concentrating systems and to answer questions regarding those systems. In the link to the small document entitled "The size of the focal spot of an ideal parabolic dish solar concentrator" the question of what is the size of the spot of concentrating sunlight that a parabolic dish produces in a plane normal to its optical axis and at a distance equal to its focal length is answered.

The link also shows how Tonatiuh can be used to provide an approximate numerical answer to the question and analyzes the associated errors, which are shown to be relatively low (< 0.35%) even when the number of rays traced is not exceedingly large (< 65 million rays).

Saturday, August 6, 2011

Release version 1.2.1 of Tonatiuh


We just released version 1.2.1 of Tonatiuh. This new release of Tonatiuh is a relatively minor release of the program. With respect to version 1.2.0, the new release:
  • Corrects few minor bugs, and
  • Adds a new shape plug-in to the list of Tonatiuh plug-ins.
The main contribution of this new program release is that, for the first time, it offers Window users the possibility of downloading a 64-bit version of the program. Thus, allowing those user to unleash the full power of the program.

We will do our best to ensure that in the next release of the program we will also provide Mac users with a 64-bit version of Tonatiuh. That new release is scheduled by September 20th. 

Friday, April 22, 2011

Release version 1.2.0 of Tonatiuh

We just released version 1.2.0 of Tonatiuh. This new release version of Tonatiuh is a relatively major release of the program. It changes:
  • the way the surface from which the primary rays are cast into the concentrating geometry is defined, and
  • the way the ray intersections are stored into the photon map.
In previous versions of Tonatiuh, the surface from which the primary rays are cast into the concentrating system was defined by the user, who had the option to select the shape of the surface between a flat rectangle and a flat circular disk, and to define the position and dimensions of the selected shape.

The attempt made in Tonatiuh's version 1.1.5 to assist the user in defining the appropriate dimensions of the selected primary ray casting surface was relatively ill-conceived. In certain circumstances, it resulted in errors in the way primary rays were casts. Furthermore, it did not facilitate the automation of Tonatiuh runs at different sun positions.

In this new release of the Tonatiuh, the primary ray casting surface is always a flat rectangle whose size and position is defined by the program. The way this primary ray casting surface is sized and positioned is simple. For a given Sun position, the bounding box of the concentrating system in the Sun's coordinate frame is obtained, and the primary ray casting surface defined as the side of this bounding box that is perpendicular to the main direction of the Sun rays and is closer to the Sun.

Depending of the Sun position and of the geometry of the solar concentrating system, there may be cases in which the size of the primary ray casting surface may be too large in relation to the region of that surface from which the rays have real chances of intersecting the concentrating system. To cope with those cases in an efficient way, a scheme has been designed and implemented in this new version of Tonatiuh so that no primary rays are cast from regions of the primary ray casting surface from which no primary casted ray will intersect the concentrating geometry. This scheme consist in:

  • Pixelizing the primary ray casting surface,
  • Projecting into the primary ray casting surface and along the main direction of the Sun rays, the bounding boxes of each of the surfaces that form the solar concentrating system.
  • Marking the pixels of the pixelized primary ray casting surface that are shadowed by the bounding boxes projections.
  • Casting primary rays to the concentrating systems only from those regions of the primary casting surface that correspond to regions of the marked pixels.
  • The refinement of this scheme, to further improve ray casting efficiency, will be one of the goals of next releases of Tonatiuh.

As stated before, this new version of the program, in addition to change the way the primary ray casting surface is shaped, sized and positioned, also changes the way the ray - surface intersections are stored in the photon map. The purpose of this change is to discriminate in which side of the surface the ray - surface intersection has taken place. The lack of this discrimination in previous versions of Tonatiuh led to the necessity of having to use two surfaces instead of one in those cases in which was likely that a surface will receive rays from both sides. Thus, this new functionality will simplify the way concentrating geometries are modeled in Tonatiuh.