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#ifndef lint |
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static const char RCSid[] = "$Id$"; |
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#endif |
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/* |
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* gendaymtx.c |
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* |
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* Generate a daylight matrix based on Perez Sky Model. |
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* |
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* Most of this code is borrowed (see copyright below) from Ian Ashdown's |
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* excellent re-implementation of Jean-Jacques Delaunay's gendaylit.c |
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* |
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* Created by Greg Ward on 1/16/13. |
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*/ |
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|
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/********************************************************************* |
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* |
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* H32_gendaylit.CPP - Perez Sky Model Calculation |
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* |
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* Version: 1.00A |
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* |
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* History: 09/10/01 - Created. |
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* 11/10/08 - Modified for Unix compilation. |
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* 11/10/12 - Fixed conditional __max directive. |
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* 1/11/13 - Tweaks and optimizations (G.Ward) |
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* |
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* Compilers: Microsoft Visual C/C++ Professional V10.0 |
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* |
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* Author: Ian Ashdown, P.Eng. |
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* byHeart Consultants Limited |
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* 620 Ballantree Road |
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* West Vancouver, B.C. |
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* Canada V7S 1W3 |
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* e-mail: [email protected] |
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* |
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* References: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. |
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* Stewart. 1990. ìModeling Daylight Availability and |
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* Irradiance Components from Direct and Global |
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* Irradiance,î Solar Energy 44(5):271-289. |
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* |
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* Perez, R., R. Seals, and J. Michalsky. 1993. |
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* ìAll-Weather Model for Sky Luminance Distribution - |
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* Preliminary Configuration and Validation,î Solar Energy |
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* 50(3):235-245. |
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* |
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* Perez, R., R. Seals, and J. Michalsky. 1993. "ERRATUM to |
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* All-Weather Model for Sky Luminance Distribution - |
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* Preliminary Configuration and Validation,î Solar Energy |
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* 51(5):423. |
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* |
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* NOTE: This program is a completely rewritten version of |
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* gendaylit.c written by Jean-Jacques Delaunay (1994). |
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* |
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* Copyright 2009-2012 byHeart Consultants Limited. All rights |
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* reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted for personal and commercial purposes |
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* provided that redistribution of source code must retain the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer: |
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* |
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* THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED |
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
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* DISCLAIMED. IN NO EVENT SHALL byHeart Consultants Limited OR |
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* ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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*********************************************************************/ |
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|
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/* Zenith is along the Z-axis */ |
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/* X-axis points east */ |
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/* Y-axis points north */ |
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/* azimuth is measured as degrees or radians east of North */ |
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|
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/* Include files */ |
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#define _USE_MATH_DEFINES |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <ctype.h> |
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#include "rtmath.h" |
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#include "color.h" |
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|
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char *progname; /* Program name */ |
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char errmsg[128]; /* Error message buffer */ |
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const double DC_SolarConstantE = 1367.0; /* Solar constant W/m^2 */ |
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const double DC_SolarConstantL = 127.5; /* Solar constant klux */ |
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|
| 96 |
double altitude; /* Solar altitude (radians) */ |
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double azimuth; /* Solar azimuth (radians) */ |
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double apwc; /* Atmospheric precipitable water content */ |
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double dew_point = 11.0; /* Surface dew point temperature (deg. C) */ |
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double diff_illum; /* Diffuse illuminance */ |
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double diff_irrad; /* Diffuse irradiance */ |
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double dir_illum; /* Direct illuminance */ |
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double dir_irrad; /* Direct irradiance */ |
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int julian_date; /* Julian date */ |
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double perez_param[5]; /* Perez sky model parameters */ |
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double sky_brightness; /* Sky brightness */ |
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double sky_clearness; /* Sky clearness */ |
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double solar_rad; /* Solar radiance */ |
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double sun_zenith; /* Sun zenith angle (radians) */ |
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int input = 0; /* Input type */ |
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|
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extern double dmax( double, double ); |
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extern double CalcAirMass(); |
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extern double CalcDiffuseIllumRatio( int ); |
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extern double CalcDiffuseIrradiance(); |
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extern double CalcDirectIllumRatio( int ); |
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extern double CalcDirectIrradiance(); |
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extern double CalcEccentricity(); |
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extern double CalcPrecipWater( double ); |
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extern double CalcRelHorzIllum( float *parr ); |
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extern double CalcRelLuminance( double, double ); |
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extern double CalcSkyBrightness(); |
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extern double CalcSkyClearness(); |
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extern int CalcSkyParamFromIllum(); |
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extern int GetCategoryIndex(); |
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extern void CalcPerezParam( double, double, double, int ); |
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extern void CalcSkyPatchLumin( float *parr ); |
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extern void ComputeSky( float *parr ); |
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|
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/* Degrees into radians */ |
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#define DegToRad(deg) ((deg)*(PI/180.)) |
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|
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/* Radiuans into degrees */ |
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#define RadToDeg(rad) ((rad)*(180./PI)) |
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|
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|
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/* Perez sky model coefficients */ |
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|
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/* Reference: Perez, R., R. Seals, and J. Michalsky, 1993. "All- */ |
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/* Weather Model for Sky Luminance Distribution - */ |
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/* Preliminary Configuration and Validation," Solar */ |
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/* Energy 50(3):235-245, Table 1. */ |
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|
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static const double PerezCoeff[8][20] = |
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{ |
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/* Sky clearness (epsilon): 1.000 to 1.065 */ |
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{ 1.3525, -0.2576, -0.2690, -1.4366, -0.7670, |
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0.0007, 1.2734, -0.1233, 2.8000, 0.6004, |
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1.2375, 1.0000, 1.8734, 0.6297, 0.9738, |
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0.2809, 0.0356, -0.1246, -0.5718, 0.9938 }, |
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/* Sky clearness (epsilon): 1.065 to 1.230 */ |
| 152 |
{ -1.2219, -0.7730, 1.4148, 1.1016, -0.2054, |
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0.0367, -3.9128, 0.9156, 6.9750, 0.1774, |
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6.4477, -0.1239, -1.5798, -0.5081, -1.7812, |
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0.1080, 0.2624, 0.0672, -0.2190, -0.4285 }, |
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/* Sky clearness (epsilon): 1.230 to 1.500 */ |
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{ -1.1000, -0.2515, 0.8952, 0.0156, 0.2782, |
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-0.1812, - 4.5000, 1.1766, 24.7219, -13.0812, |
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-37.7000, 34.8438, -5.0000, 1.5218, 3.9229, |
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-2.6204, -0.0156, 0.1597, 0.4199, -0.5562 }, |
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/* Sky clearness (epsilon): 1.500 to 1.950 */ |
| 162 |
{ -0.5484, -0.6654, -0.2672, 0.7117, 0.7234, |
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-0.6219, -5.6812, 2.6297, 33.3389, -18.3000, |
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-62.2500, 52.0781, -3.5000, 0.0016, 1.1477, |
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0.1062, 0.4659, -0.3296, -0.0876, -0.0329 }, |
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/* Sky clearness (epsilon): 1.950 to 2.800 */ |
| 167 |
{ -0.6000, -0.3566, -2.5000, 2.3250, 0.2937, |
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0.0496, -5.6812, 1.8415, 21.0000, -4.7656 , |
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-21.5906, 7.2492, -3.5000, -0.1554, 1.4062, |
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0.3988, 0.0032, 0.0766, -0.0656, -0.1294 }, |
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/* Sky clearness (epsilon): 2.800 to 4.500 */ |
| 172 |
{ -1.0156, -0.3670, 1.0078, 1.4051, 0.2875, |
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-0.5328, -3.8500, 3.3750, 14.0000, -0.9999, |
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-7.1406, 7.5469, -3.4000, -0.1078, -1.0750, |
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1.5702, -0.0672, 0.4016, 0.3017, -0.4844 }, |
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/* Sky clearness (epsilon): 4.500 to 6.200 */ |
| 177 |
{ -1.0000, 0.0211, 0.5025, -0.5119, -0.3000, |
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0.1922, 0.7023, -1.6317, 19.0000, -5.0000, |
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1.2438, -1.9094, -4.0000, 0.0250, 0.3844, |
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0.2656, 1.0468, -0.3788, -2.4517, 1.4656 }, |
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/* Sky clearness (epsilon): 6.200 to ... */ |
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{ -1.0500, 0.0289, 0.4260, 0.3590, -0.3250, |
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0.1156, 0.7781, 0.0025, 31.0625, -14.5000, |
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-46.1148, 55.3750, -7.2312, 0.4050, 13.3500, |
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0.6234, 1.5000, -0.6426, 1.8564, 0.5636 } |
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}; |
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|
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/* Perez irradiance component model coefficients */ |
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|
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/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
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/* Stewart. 1990. ìModeling Daylight Availability and */ |
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/* Irradiance Components from Direct and Global */ |
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/* Irradiance,î Solar Energy 44(5):271-289. */ |
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|
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typedef struct |
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{ |
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double lower; /* Lower bound */ |
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double upper; /* Upper bound */ |
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} CategoryBounds; |
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|
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/* Perez sky clearness (epsilon) categories (Table 1) */ |
| 202 |
static const CategoryBounds SkyClearCat[8] = |
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{ |
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{ 1.000, 1.065 }, /* Overcast */ |
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{ 1.065, 1.230 }, |
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{ 1.230, 1.500 }, |
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{ 1.500, 1.950 }, |
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{ 1.950, 2.800 }, |
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{ 2.800, 4.500 }, |
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{ 4.500, 6.200 }, |
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{ 6.200, 12.00 } /* Clear */ |
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}; |
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|
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/* Luminous efficacy model coefficients */ |
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typedef struct |
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{ |
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double a; |
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double b; |
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double c; |
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double d; |
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} ModelCoeff; |
| 222 |
|
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/* Diffuse luminous efficacy model coefficients (Table 4, Eqn. 7) */ |
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static const ModelCoeff DiffuseLumEff[8] = |
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{ |
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{ 97.24, -0.46, 12.00, -8.91 }, |
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{ 107.22, 1.15, 0.59, -3.95 }, |
| 228 |
{ 104.97, 2.96, -5.53, -8.77 }, |
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{ 102.39, 5.59, -13.95, -13.90 }, |
| 230 |
{ 100.71, 5.94, -22.75, -23.74 }, |
| 231 |
{ 106.42, 3.83, -36.15, -28.83 }, |
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{ 141.88, 1.90, -53.24, -14.03 }, |
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{ 152.23, 0.35, -45.27, -7.98 } |
| 234 |
}; |
| 235 |
|
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/* Direct luminous efficacy model coefficients (Table 4, Eqn. 8) */ |
| 237 |
static const ModelCoeff DirectLumEff[8] = |
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{ |
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{ 57.20, -4.55, -2.98, 117.12 }, |
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{ 98.99, -3.46, -1.21, 12.38 }, |
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{ 109.83, -4.90, -1.71, -8.81 }, |
| 242 |
{ 110.34, -5.84, -1.99, -4.56 }, |
| 243 |
{ 106.36, -3.97, -1.75, -6.16 }, |
| 244 |
{ 107.19, -1.25, -1.51, -26.73 }, |
| 245 |
{ 105.75, 0.77, -1.26, -34.44 }, |
| 246 |
{ 101.18, 1.58, -1.10, -8.29 } |
| 247 |
}; |
| 248 |
|
| 249 |
extern int jdate(int month, int day); |
| 250 |
extern double stadj(int jd); |
| 251 |
extern double sdec(int jd); |
| 252 |
extern double salt(double sd, double st); |
| 253 |
extern double sazi(double sd, double st); |
| 254 |
/* sun calculation constants */ |
| 255 |
extern double s_latitude; |
| 256 |
extern double s_longitude; |
| 257 |
extern double s_meridian; |
| 258 |
|
| 259 |
double grefl = 0.2; /* diffuse ground reflectance */ |
| 260 |
|
| 261 |
int verbose = 0; /* progress reports to stderr? */ |
| 262 |
|
| 263 |
int outfmt = 'a'; /* output format */ |
| 264 |
|
| 265 |
int rhsubdiv = 1; /* Reinhart sky subdivisions */ |
| 266 |
|
| 267 |
float skycolor[3] = {.96, 1.004, 1.118}; /* sky coloration */ |
| 268 |
|
| 269 |
int do_sun = 1; /* output direct solar contribution? */ |
| 270 |
|
| 271 |
int nskypatch; /* number of Reinhart patches */ |
| 272 |
float *rh_palt; /* sky patch altitudes (radians) */ |
| 273 |
float *rh_pazi; /* sky patch azimuths (radians) */ |
| 274 |
float *rh_dom; /* sky patch solid angle (sr) */ |
| 275 |
|
| 276 |
#define vector(v,alt,azi) ( (v)[1] = tcos(alt), \ |
| 277 |
(v)[0] = (v)[1]*tsin(azi), \ |
| 278 |
(v)[1] *= tcos(azi), \ |
| 279 |
(v)[2] = tsin(alt) ) |
| 280 |
|
| 281 |
#define rh_vector(v,i) vector(v,rh_palt[i],rh_pazi[i]) |
| 282 |
|
| 283 |
#define rh_cos(i) tsin(rh_palt[i]) |
| 284 |
|
| 285 |
extern int rh_init(void); |
| 286 |
extern float * resize_dmatrix(float *mtx_data, int nsteps, int npatch); |
| 287 |
extern void AddDirect(float *parr); |
| 288 |
|
| 289 |
int |
| 290 |
main(int argc, char *argv[]) |
| 291 |
{ |
| 292 |
char buf[256]; |
| 293 |
double elevation; /* site elevation (meters) */ |
| 294 |
int dir_is_horiz; /* direct is meas. on horizontal? */ |
| 295 |
float *mtx_data = NULL; /* our matrix data */ |
| 296 |
int ntsteps = 0; /* number of rows in matrix */ |
| 297 |
int last_monthly = 0; /* month of last report */ |
| 298 |
int mo, da; /* month (1-12) and day (1-31) */ |
| 299 |
double hr; /* hour (local standard time) */ |
| 300 |
double dir, dif; /* direct and diffuse values */ |
| 301 |
int mtx_offset; |
| 302 |
int i, j; |
| 303 |
|
| 304 |
progname = argv[0]; |
| 305 |
/* get options */ |
| 306 |
for (i = 1; i < argc && argv[i][0] == '-'; i++) |
| 307 |
switch (argv[i][1]) { |
| 308 |
case 'g': |
| 309 |
grefl = atof(argv[++i]); |
| 310 |
break; |
| 311 |
case 'v': |
| 312 |
verbose++; |
| 313 |
break; |
| 314 |
case 'o': |
| 315 |
switch (argv[i][2]) { |
| 316 |
case 'f': |
| 317 |
case 'd': |
| 318 |
case 'a': |
| 319 |
outfmt = argv[i][2]; |
| 320 |
break; |
| 321 |
default: |
| 322 |
goto userr; |
| 323 |
} |
| 324 |
break; |
| 325 |
case 'm': |
| 326 |
rhsubdiv = atoi(argv[++i]); |
| 327 |
break; |
| 328 |
case 'c': |
| 329 |
skycolor[0] = atof(argv[++i]); |
| 330 |
skycolor[1] = atof(argv[++i]); |
| 331 |
skycolor[2] = atof(argv[++i]); |
| 332 |
break; |
| 333 |
case 'd': |
| 334 |
do_sun = 1; |
| 335 |
skycolor[0] = skycolor[1] = skycolor[2] = 0; |
| 336 |
break; |
| 337 |
case 's': |
| 338 |
do_sun = 0; |
| 339 |
if (skycolor[1] <= 1e-4) |
| 340 |
skycolor[0] = skycolor[1] = skycolor[2] = 1; |
| 341 |
break; |
| 342 |
default: |
| 343 |
goto userr; |
| 344 |
} |
| 345 |
if (i < argc-1) |
| 346 |
goto userr; |
| 347 |
if (i == argc-1 && freopen(argv[i], "r", stdin) == NULL) { |
| 348 |
fprintf(stderr, "%s: cannot open '%s' for input\n", |
| 349 |
progname, argv[i]); |
| 350 |
exit(1); |
| 351 |
} |
| 352 |
if (verbose) { |
| 353 |
if (i == argc-1) |
| 354 |
fprintf(stderr, "%s: reading weather tape '%s'\n", |
| 355 |
progname, argv[i]); |
| 356 |
else |
| 357 |
fprintf(stderr, "%s: reading weather tape from <stdin>\n", |
| 358 |
progname); |
| 359 |
} |
| 360 |
/* read weather tape header */ |
| 361 |
if (scanf("place %[^\n]\n", buf) != 1) |
| 362 |
goto fmterr; |
| 363 |
if (scanf("latitude %lf\n", &s_latitude) != 1) |
| 364 |
goto fmterr; |
| 365 |
if (scanf("longitude %lf\n", &s_longitude) != 1) |
| 366 |
goto fmterr; |
| 367 |
if (scanf("time_zone %lf\n", &s_meridian) != 1) |
| 368 |
goto fmterr; |
| 369 |
if (scanf("site_elevation %lf\n", &elevation) != 1) |
| 370 |
goto fmterr; |
| 371 |
if (scanf("weather_data_file_units %d\n", &input) != 1) |
| 372 |
goto fmterr; |
| 373 |
switch (input) { /* translate units */ |
| 374 |
case 1: |
| 375 |
input = 1; /* radiometric quantities */ |
| 376 |
dir_is_horiz = 0; /* direct is perpendicular meas. */ |
| 377 |
break; |
| 378 |
case 2: |
| 379 |
input = 1; /* radiometric quantities */ |
| 380 |
dir_is_horiz = 1; /* solar measured horizontally */ |
| 381 |
break; |
| 382 |
case 3: |
| 383 |
input = 2; /* photometric quantities */ |
| 384 |
dir_is_horiz = 0; /* direct is perpendicular meas. */ |
| 385 |
break; |
| 386 |
default: |
| 387 |
goto fmterr; |
| 388 |
} |
| 389 |
rh_init(); /* initialize sky patches */ |
| 390 |
if (verbose) { |
| 391 |
fprintf(stderr, "%s: location '%s'\n", progname, buf); |
| 392 |
fprintf(stderr, "%s: (lat,long)=(%.1f,%.1f) degrees north, west\n", |
| 393 |
progname, s_latitude, s_longitude); |
| 394 |
fprintf(stderr, "%s: %d sky patches per time step\n", |
| 395 |
progname, nskypatch); |
| 396 |
} |
| 397 |
/* process each time step in tape */ |
| 398 |
while (scanf("%d %d %lf %lf %lf\n", &mo, &da, &hr, &dir, &dif) == 5) { |
| 399 |
double sda, sta; |
| 400 |
/* make space for next time step */ |
| 401 |
mtx_offset = 3*nskypatch*ntsteps++; |
| 402 |
mtx_data = resize_dmatrix(mtx_data, ntsteps, nskypatch); |
| 403 |
if (dif <= 1e-4) { |
| 404 |
memset(mtx_data+mtx_offset, 0, sizeof(float)*3*nskypatch); |
| 405 |
continue; |
| 406 |
} |
| 407 |
if (verbose && mo != last_monthly) |
| 408 |
fprintf(stderr, "%s: stepping through month %d...\n", |
| 409 |
progname, last_monthly=mo); |
| 410 |
/* compute solar position */ |
| 411 |
julian_date = jdate(mo, da); |
| 412 |
sda = sdec(julian_date); |
| 413 |
sta = stadj(julian_date); |
| 414 |
altitude = salt(sda, hr+sta); |
| 415 |
azimuth = sazi(sda, hr+sta); |
| 416 |
/* convert measured values */ |
| 417 |
if (dir_is_horiz && altitude > 0.) |
| 418 |
dir /= sin(altitude); |
| 419 |
if (input == 1) { |
| 420 |
dir_irrad = dir; |
| 421 |
diff_irrad = dif; |
| 422 |
} else /* input == 2 */ { |
| 423 |
dir_illum = dir; |
| 424 |
diff_illum = dif; |
| 425 |
} |
| 426 |
/* compute sky patch values */ |
| 427 |
ComputeSky(mtx_data+mtx_offset); |
| 428 |
if (do_sun) |
| 429 |
AddDirect(mtx_data+mtx_offset); |
| 430 |
} |
| 431 |
/* check for junk at end */ |
| 432 |
while ((i = fgetc(stdin)) != EOF) |
| 433 |
if (!isspace(i)) { |
| 434 |
fprintf(stderr, "%s: warning - unexpected data past EOT: ", |
| 435 |
progname); |
| 436 |
buf[0] = i; buf[1] = '\0'; |
| 437 |
fgets(buf+1, sizeof(buf)-1, stdin); |
| 438 |
fputs(buf, stderr); fputc('\n', stderr); |
| 439 |
break; |
| 440 |
} |
| 441 |
/* write out matrix */ |
| 442 |
#ifdef getc_unlocked |
| 443 |
flockfile(stdout); |
| 444 |
#endif |
| 445 |
if (verbose) |
| 446 |
fprintf(stderr, "%s: writing %smatrix with %d time steps...\n", |
| 447 |
progname, outfmt=='a' ? "" : "binary ", ntsteps); |
| 448 |
/* patches are rows (outer sort) */ |
| 449 |
for (i = 0; i < nskypatch; i++) { |
| 450 |
mtx_offset = 3*i; |
| 451 |
switch (outfmt) { |
| 452 |
case 'a': |
| 453 |
for (j = 0; j < ntsteps; j++) { |
| 454 |
printf("%.3e %.3e %.3e\n", mtx_data[mtx_offset], |
| 455 |
mtx_data[mtx_offset+1], |
| 456 |
mtx_data[mtx_offset+2]); |
| 457 |
mtx_offset += 3*nskypatch; |
| 458 |
} |
| 459 |
fputc('\n', stdout); |
| 460 |
break; |
| 461 |
case 'f': |
| 462 |
for (j = 0; j < ntsteps; j++) { |
| 463 |
fwrite(mtx_data+mtx_offset, sizeof(float), 3, |
| 464 |
stdout); |
| 465 |
mtx_offset += 3*nskypatch; |
| 466 |
} |
| 467 |
break; |
| 468 |
case 'd': |
| 469 |
for (j = 0; j < ntsteps; j++) { |
| 470 |
double ment[3]; |
| 471 |
ment[0] = mtx_data[mtx_offset]; |
| 472 |
ment[1] = mtx_data[mtx_offset+1]; |
| 473 |
ment[2] = mtx_data[mtx_offset+2]; |
| 474 |
fwrite(ment, sizeof(double), 3, stdout); |
| 475 |
mtx_offset += 3*nskypatch; |
| 476 |
} |
| 477 |
break; |
| 478 |
} |
| 479 |
if (ferror(stdout)) |
| 480 |
goto writerr; |
| 481 |
} |
| 482 |
if (fflush(stdout) == EOF) |
| 483 |
goto writerr; |
| 484 |
if (verbose) |
| 485 |
fprintf(stderr, "%s: done.\n", progname); |
| 486 |
exit(0); |
| 487 |
userr: |
| 488 |
fprintf(stderr, "Usage: %s [-v][-d|-s][-m N][-g refl][-c r g b][-o{f|d}] [tape.wea]\n", |
| 489 |
progname); |
| 490 |
exit(1); |
| 491 |
fmterr: |
| 492 |
fprintf(stderr, "%s: input weather tape format error\n", progname); |
| 493 |
exit(1); |
| 494 |
writerr: |
| 495 |
fprintf(stderr, "%s: write error on output\n", progname); |
| 496 |
exit(1); |
| 497 |
} |
| 498 |
|
| 499 |
/* Return maximum of two doubles */ |
| 500 |
double dmax( double a, double b ) |
| 501 |
{ return (a > b) ? a : b; } |
| 502 |
|
| 503 |
/* Compute sky patch radiance values (modified by GW) */ |
| 504 |
void |
| 505 |
ComputeSky(float *parr) |
| 506 |
{ |
| 507 |
int index; /* Category index */ |
| 508 |
double norm_diff_illum; /* Normalized diffuse illuimnance */ |
| 509 |
double zlumin; /* Zenith luminance */ |
| 510 |
int i; |
| 511 |
|
| 512 |
if (bright(skycolor) <= 1e-4) { /* 0 sky component? */ |
| 513 |
memset(parr, 0, sizeof(float)*3*nskypatch); |
| 514 |
return; |
| 515 |
} |
| 516 |
|
| 517 |
/* Calculate atmospheric precipitable water content */ |
| 518 |
apwc = CalcPrecipWater(dew_point); |
| 519 |
|
| 520 |
/* Limit solar altitude to keep circumsolar off zenith */ |
| 521 |
if (altitude > DegToRad(87.0)) |
| 522 |
altitude = DegToRad(87.0); |
| 523 |
|
| 524 |
/* Calculate sun zenith angle */ |
| 525 |
sun_zenith = DegToRad(90.0) - altitude; |
| 526 |
|
| 527 |
/* Compute the inputs for the calculation of the sky distribution */ |
| 528 |
|
| 529 |
if (input == 0) /* XXX never used */ |
| 530 |
{ |
| 531 |
/* Calculate irradiance */ |
| 532 |
diff_irrad = CalcDiffuseIrradiance(); |
| 533 |
dir_irrad = CalcDirectIrradiance(); |
| 534 |
|
| 535 |
/* Calculate illuminance */ |
| 536 |
index = GetCategoryIndex(); |
| 537 |
diff_illum = diff_irrad * CalcDiffuseIllumRatio(index); |
| 538 |
dir_illum = dir_irrad * CalcDirectIllumRatio(index); |
| 539 |
} |
| 540 |
else if (input == 1) |
| 541 |
{ |
| 542 |
sky_brightness = CalcSkyBrightness(); |
| 543 |
sky_clearness = CalcSkyClearness(); |
| 544 |
|
| 545 |
/* Calculate illuminance */ |
| 546 |
index = GetCategoryIndex(); |
| 547 |
diff_illum = diff_irrad * CalcDiffuseIllumRatio(index); |
| 548 |
dir_illum = dir_irrad * CalcDirectIllumRatio(index); |
| 549 |
} |
| 550 |
else if (input == 2) |
| 551 |
{ |
| 552 |
/* Calculate sky brightness and clearness from illuminance values */ |
| 553 |
index = CalcSkyParamFromIllum(); |
| 554 |
} |
| 555 |
|
| 556 |
/* Compute ground radiance (include solar contribution if any) */ |
| 557 |
parr[0] = diff_illum * (1./PI/WHTEFFICACY); |
| 558 |
if (altitude > 0) |
| 559 |
parr[0] += dir_illum * sin(altitude) * (1./PI/WHTEFFICACY); |
| 560 |
parr[2] = parr[1] = parr[0]; |
| 561 |
|
| 562 |
/* Calculate Perez sky model parameters */ |
| 563 |
CalcPerezParam(sun_zenith, sky_clearness, sky_brightness, index); |
| 564 |
|
| 565 |
/* Calculate sky patch luminance values */ |
| 566 |
CalcSkyPatchLumin(parr); |
| 567 |
|
| 568 |
/* Calculate relative horizontal illuminance */ |
| 569 |
norm_diff_illum = CalcRelHorzIllum(parr); |
| 570 |
|
| 571 |
/* Normalization coefficient */ |
| 572 |
norm_diff_illum = diff_illum / norm_diff_illum; |
| 573 |
|
| 574 |
/* Calculate relative zenith luminance */ |
| 575 |
zlumin = CalcRelLuminance(sun_zenith, 0.0); |
| 576 |
|
| 577 |
/* Calculate absolute zenith illuminance */ |
| 578 |
zlumin *= norm_diff_illum; |
| 579 |
|
| 580 |
/* Apply to sky patches to get absolute radiance values */ |
| 581 |
for (i = 1; i < nskypatch; i++) { |
| 582 |
scalecolor(parr+3*i, zlumin*(1./WHTEFFICACY)); |
| 583 |
multcolor(parr+3*i, skycolor); |
| 584 |
} |
| 585 |
} |
| 586 |
|
| 587 |
/* Add in solar direct to nearest sky patches (GW) */ |
| 588 |
void |
| 589 |
AddDirect(float *parr) |
| 590 |
{ |
| 591 |
FVECT svec; |
| 592 |
double near_dprod[4]; |
| 593 |
int near_patch[4]; |
| 594 |
double wta[4], wtot; |
| 595 |
int i, j, p; |
| 596 |
|
| 597 |
if (!do_sun || dir_illum < 1e-4) |
| 598 |
return; |
| 599 |
/* identify 4 closest patches */ |
| 600 |
for (i = 4; i--; ) |
| 601 |
near_dprod[i] = -1.; |
| 602 |
vector(svec, altitude, azimuth); |
| 603 |
for (p = 1; p < nskypatch; p++) { |
| 604 |
FVECT pvec; |
| 605 |
double dprod; |
| 606 |
rh_vector(pvec, p); |
| 607 |
dprod = DOT(pvec, svec); |
| 608 |
for (i = 0; i < 4; i++) |
| 609 |
if (dprod > near_dprod[i]) { |
| 610 |
for (j = 4; --j > i; ) { |
| 611 |
near_dprod[j] = near_dprod[j-1]; |
| 612 |
near_patch[j] = near_patch[j-1]; |
| 613 |
} |
| 614 |
near_dprod[i] = dprod; |
| 615 |
near_patch[i] = p; |
| 616 |
break; |
| 617 |
} |
| 618 |
} |
| 619 |
wtot = 0; /* weight by proximity */ |
| 620 |
for (i = 4; i--; ) |
| 621 |
wtot += wta[i] = 1./(1.002 - near_dprod[i]); |
| 622 |
/* add to nearest patch radiances */ |
| 623 |
for (i = 4; i--; ) |
| 624 |
parr[near_patch[i]] += wta[i] * dir_illum / |
| 625 |
(wtot * rh_dom[near_patch[i]]); |
| 626 |
} |
| 627 |
|
| 628 |
/* Initialize Reinhart sky patch positions (GW) */ |
| 629 |
int |
| 630 |
rh_init(void) |
| 631 |
{ |
| 632 |
#define NROW 7 |
| 633 |
static const int tnaz[NROW] = {30, 30, 24, 24, 18, 12, 6}; |
| 634 |
const double alpha = (PI/2.)/(NROW*rhsubdiv + .5); |
| 635 |
int p, i, j; |
| 636 |
/* allocate patch angle arrays */ |
| 637 |
nskypatch = 0; |
| 638 |
for (p = 0; p < NROW; p++) |
| 639 |
nskypatch += tnaz[p]; |
| 640 |
nskypatch *= rhsubdiv*rhsubdiv; |
| 641 |
nskypatch += 2; |
| 642 |
rh_palt = (float *)malloc(sizeof(float)*nskypatch); |
| 643 |
rh_pazi = (float *)malloc(sizeof(float)*nskypatch); |
| 644 |
rh_dom = (float *)malloc(sizeof(float)*nskypatch); |
| 645 |
if ((rh_palt == NULL) | (rh_pazi == NULL) | (rh_dom == NULL)) { |
| 646 |
fprintf(stderr, "%s: out of memory in rh_init()\n", progname); |
| 647 |
exit(1); |
| 648 |
} |
| 649 |
rh_palt[0] = -PI/2.; /* ground & zenith patches */ |
| 650 |
rh_pazi[0] = 0.; |
| 651 |
rh_dom[0] = 2.*PI; |
| 652 |
rh_palt[nskypatch-1] = PI/2.; |
| 653 |
rh_pazi[nskypatch-1] = 0.; |
| 654 |
rh_dom[nskypatch-1] = 2.*PI*(1. - cos(alpha*.5)); |
| 655 |
p = 1; /* "normal" patches */ |
| 656 |
for (i = 0; i < NROW*rhsubdiv; i++) { |
| 657 |
const float ralt = alpha*(i + .5); |
| 658 |
const int ninrow = tnaz[i/rhsubdiv]*rhsubdiv; |
| 659 |
const float dom = (sin(alpha*(i+1)) - sin(alpha*i))/ninrow; |
| 660 |
for (j = 0; j < ninrow; j++) { |
| 661 |
rh_palt[p] = ralt; |
| 662 |
rh_pazi[p] = 2.*PI * j / (double)ninrow; |
| 663 |
rh_dom[p++] = dom; |
| 664 |
} |
| 665 |
} |
| 666 |
return nskypatch; |
| 667 |
#undef NROW |
| 668 |
} |
| 669 |
|
| 670 |
/* Resize daylight matrix (GW) */ |
| 671 |
float * |
| 672 |
resize_dmatrix(float *mtx_data, int nsteps, int npatch) |
| 673 |
{ |
| 674 |
if (mtx_data == NULL) |
| 675 |
mtx_data = (float *)malloc(sizeof(float)*3*nsteps*npatch); |
| 676 |
else |
| 677 |
mtx_data = (float *)realloc(mtx_data, |
| 678 |
sizeof(float)*3*nsteps*npatch); |
| 679 |
if (mtx_data == NULL) { |
| 680 |
fprintf(stderr, "%s: out of memory in resize_dmatrix(%d,%d)\n", |
| 681 |
progname, nsteps, npatch); |
| 682 |
exit(1); |
| 683 |
} |
| 684 |
return(mtx_data); |
| 685 |
} |
| 686 |
|
| 687 |
/* Determine category index */ |
| 688 |
int GetCategoryIndex() |
| 689 |
{ |
| 690 |
int index; /* Loop index */ |
| 691 |
|
| 692 |
for (index = 0; index < 8; index++) |
| 693 |
if ((sky_clearness >= SkyClearCat[index].lower) && |
| 694 |
(sky_clearness < SkyClearCat[index].upper)) |
| 695 |
break; |
| 696 |
|
| 697 |
return index; |
| 698 |
} |
| 699 |
|
| 700 |
/* Calculate diffuse illuminance to diffuse irradiance ratio */ |
| 701 |
|
| 702 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
| 703 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
| 704 |
/* Irradiance Components from Direct and Global */ |
| 705 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 7. */ |
| 706 |
|
| 707 |
double CalcDiffuseIllumRatio( int index ) |
| 708 |
{ |
| 709 |
ModelCoeff const *pnle; /* Category coefficient pointer */ |
| 710 |
|
| 711 |
/* Get category coefficient pointer */ |
| 712 |
pnle = &(DiffuseLumEff[index]); |
| 713 |
|
| 714 |
return pnle->a + pnle->b * apwc + pnle->c * cos(sun_zenith) + |
| 715 |
pnle->d * log(sky_brightness); |
| 716 |
} |
| 717 |
|
| 718 |
/* Calculate direct illuminance to direct irradiance ratio */ |
| 719 |
|
| 720 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
| 721 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
| 722 |
/* Irradiance Components from Direct and Global */ |
| 723 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 8. */ |
| 724 |
|
| 725 |
double CalcDirectIllumRatio( int index ) |
| 726 |
{ |
| 727 |
ModelCoeff const *pnle; /* Category coefficient pointer */ |
| 728 |
|
| 729 |
/* Get category coefficient pointer */ |
| 730 |
pnle = &(DirectLumEff[index]); |
| 731 |
|
| 732 |
/* Calculate direct illuminance from direct irradiance */ |
| 733 |
|
| 734 |
return dmax((pnle->a + pnle->b * apwc + pnle->c * exp(5.73 * |
| 735 |
sun_zenith - 5.0) + pnle->d * sky_brightness), |
| 736 |
0.0); |
| 737 |
} |
| 738 |
|
| 739 |
/* Calculate sky brightness */ |
| 740 |
|
| 741 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
| 742 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
| 743 |
/* Irradiance Components from Direct and Global */ |
| 744 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 2. */ |
| 745 |
|
| 746 |
double CalcSkyBrightness() |
| 747 |
{ |
| 748 |
return diff_irrad * CalcAirMass() / (DC_SolarConstantE * |
| 749 |
CalcEccentricity()); |
| 750 |
} |
| 751 |
|
| 752 |
/* Calculate sky clearness */ |
| 753 |
|
| 754 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
| 755 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
| 756 |
/* Irradiance Components from Direct and Global */ |
| 757 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 1. */ |
| 758 |
|
| 759 |
double CalcSkyClearness() |
| 760 |
{ |
| 761 |
double sz_cubed; /* Sun zenith angle cubed */ |
| 762 |
|
| 763 |
/* Calculate sun zenith angle cubed */ |
| 764 |
sz_cubed = pow(sun_zenith, 3.0); |
| 765 |
|
| 766 |
return ((diff_irrad + dir_irrad) / diff_irrad + 1.041 * |
| 767 |
sz_cubed) / (1.0 + 1.041 * sz_cubed); |
| 768 |
} |
| 769 |
|
| 770 |
/* Calculate diffuse horizontal irradiance from Perez sky brightness */ |
| 771 |
|
| 772 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
| 773 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
| 774 |
/* Irradiance Components from Direct and Global */ |
| 775 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 2 */ |
| 776 |
/* (inverse). */ |
| 777 |
|
| 778 |
double CalcDiffuseIrradiance() |
| 779 |
{ |
| 780 |
return sky_brightness * DC_SolarConstantE * CalcEccentricity() / |
| 781 |
CalcAirMass(); |
| 782 |
} |
| 783 |
|
| 784 |
/* Calculate direct normal irradiance from Perez sky clearness */ |
| 785 |
|
| 786 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
| 787 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
| 788 |
/* Irradiance Components from Direct and Global */ |
| 789 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 1 */ |
| 790 |
/* (inverse). */ |
| 791 |
|
| 792 |
double CalcDirectIrradiance() |
| 793 |
{ |
| 794 |
return CalcDiffuseIrradiance() * ((sky_clearness - 1.0) * (1 + 1.041 |
| 795 |
* pow(sun_zenith, 3.0))); |
| 796 |
} |
| 797 |
|
| 798 |
/* Calculate sky brightness and clearness from illuminance values */ |
| 799 |
int CalcSkyParamFromIllum() |
| 800 |
{ |
| 801 |
double test1 = 0.1; |
| 802 |
double test2 = 0.1; |
| 803 |
int counter = 0; |
| 804 |
int index = 0; /* Category index */ |
| 805 |
|
| 806 |
/* Convert illuminance to irradiance */ |
| 807 |
diff_irrad = diff_illum * DC_SolarConstantE / |
| 808 |
(DC_SolarConstantL * 1000.0); |
| 809 |
dir_irrad = dir_illum * DC_SolarConstantE / |
| 810 |
(DC_SolarConstantL * 1000.0); |
| 811 |
|
| 812 |
/* Calculate sky brightness and clearness */ |
| 813 |
sky_brightness = CalcSkyBrightness(); |
| 814 |
sky_clearness = CalcSkyClearness(); |
| 815 |
|
| 816 |
/* Limit sky clearness */ |
| 817 |
if (sky_clearness > 12.0) |
| 818 |
sky_clearness = 12.0; |
| 819 |
|
| 820 |
/* Limit sky brightness */ |
| 821 |
if (sky_brightness < 0.05) |
| 822 |
sky_brightness = 0.01; |
| 823 |
|
| 824 |
while (((fabs(diff_irrad - test1) > 10.0) || |
| 825 |
(fabs(dir_irrad - test2) > 10.0)) && !(counter == 5)) |
| 826 |
{ |
| 827 |
test1 = diff_irrad; |
| 828 |
test2 = dir_irrad; |
| 829 |
counter++; |
| 830 |
|
| 831 |
/* Convert illuminance to irradiance */ |
| 832 |
index = GetCategoryIndex(); |
| 833 |
diff_irrad = diff_illum / CalcDiffuseIllumRatio(index); |
| 834 |
dir_irrad = dir_illum / CalcDirectIllumRatio(index); |
| 835 |
|
| 836 |
/* Calculate sky brightness and clearness */ |
| 837 |
sky_brightness = CalcSkyBrightness(); |
| 838 |
sky_clearness = CalcSkyClearness(); |
| 839 |
|
| 840 |
/* Limit sky clearness */ |
| 841 |
if (sky_clearness > 12.0) |
| 842 |
sky_clearness = 12.0; |
| 843 |
|
| 844 |
/* Limit sky brightness */ |
| 845 |
if (sky_brightness < 0.05) |
| 846 |
sky_brightness = 0.01; |
| 847 |
} |
| 848 |
|
| 849 |
return GetCategoryIndex(); |
| 850 |
} |
| 851 |
|
| 852 |
/* Calculate relative luminance */ |
| 853 |
|
| 854 |
/* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */ |
| 855 |
/* ìAll-Weather Model for Sky Luminance Distribution - */ |
| 856 |
/* Preliminary Configuration and Validation,î Solar Energy */ |
| 857 |
/* 50(3):235-245, Eqn. 1. */ |
| 858 |
|
| 859 |
double CalcRelLuminance( double gamma, double zeta ) |
| 860 |
{ |
| 861 |
return (1.0 + perez_param[0] * exp(perez_param[1] / cos(zeta))) * |
| 862 |
(1.0 + perez_param[2] * exp(perez_param[3] * gamma) + |
| 863 |
perez_param[4] * cos(gamma) * cos(gamma)); |
| 864 |
} |
| 865 |
|
| 866 |
/* Calculate Perez sky model parameters */ |
| 867 |
|
| 868 |
/* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */ |
| 869 |
/* ìAll-Weather Model for Sky Luminance Distribution - */ |
| 870 |
/* Preliminary Configuration and Validation,î Solar Energy */ |
| 871 |
/* 50(3):235-245, Eqns. 6 - 8. */ |
| 872 |
|
| 873 |
void CalcPerezParam( double sz, double epsilon, double delta, |
| 874 |
int index ) |
| 875 |
{ |
| 876 |
double x[5][4]; /* Coefficents a, b, c, d, e */ |
| 877 |
int i, j; /* Loop indices */ |
| 878 |
|
| 879 |
/* Limit sky brightness */ |
| 880 |
if (epsilon > 1.065 && epsilon < 2.8) |
| 881 |
{ |
| 882 |
if (delta < 0.2) |
| 883 |
delta = 0.2; |
| 884 |
} |
| 885 |
|
| 886 |
/* Get Perez coefficients */ |
| 887 |
for (i = 0; i < 5; i++) |
| 888 |
for (j = 0; j < 4; j++) |
| 889 |
x[i][j] = PerezCoeff[index][4 * i + j]; |
| 890 |
|
| 891 |
if (index != 0) |
| 892 |
{ |
| 893 |
/* Calculate parameter a, b, c, d and e (Eqn. 6) */ |
| 894 |
for (i = 0; i < 5; i++) |
| 895 |
perez_param[i] = x[i][0] + x[i][1] * sz + delta * (x[i][2] + |
| 896 |
x[i][3] * sz); |
| 897 |
} |
| 898 |
else |
| 899 |
{ |
| 900 |
/* Parameters a, b and e (Eqn. 6) */ |
| 901 |
perez_param[0] = x[0][0] + x[0][1] * sz + delta * (x[0][2] + |
| 902 |
x[0][3] * sz); |
| 903 |
perez_param[1] = x[1][0] + x[1][1] * sz + delta * (x[1][2] + |
| 904 |
x[1][3] * sz); |
| 905 |
perez_param[4] = x[4][0] + x[4][1] * sz + delta * (x[4][2] + |
| 906 |
x[4][3] * sz); |
| 907 |
|
| 908 |
/* Parameter c (Eqn. 7) */ |
| 909 |
perez_param[2] = exp(pow(delta * (x[2][0] + x[2][1] * sz), |
| 910 |
x[2][2])) - x[2][3]; |
| 911 |
|
| 912 |
/* Parameter d (Eqn. 8) */ |
| 913 |
perez_param[3] = -exp(delta * (x[3][0] + x[3][1] * sz)) + |
| 914 |
x[3][2] + delta * x[3][3]; |
| 915 |
} |
| 916 |
} |
| 917 |
|
| 918 |
/* Calculate relative horizontal illuminance (modified by GW) */ |
| 919 |
|
| 920 |
/* Reference: Perez, R., R. Seals, and J. Michalsky. 1993. */ |
| 921 |
/* ìAll-Weather Model for Sky Luminance Distribution - */ |
| 922 |
/* Preliminary Configuration and Validation,î Solar Energy */ |
| 923 |
/* 50(3):235-245, Eqn. 3. */ |
| 924 |
|
| 925 |
double CalcRelHorzIllum( float *parr ) |
| 926 |
{ |
| 927 |
int i; |
| 928 |
double rh_illum = 0.0; /* Relative horizontal illuminance */ |
| 929 |
|
| 930 |
for (i = 1; i < nskypatch; i++) |
| 931 |
rh_illum += parr[3*i+1] * rh_cos(i); |
| 932 |
|
| 933 |
return rh_illum * (2.0 * PI / (nskypatch-1)); |
| 934 |
} |
| 935 |
|
| 936 |
/* Calculate earth orbit eccentricity correction factor */ |
| 937 |
|
| 938 |
/* Reference: Sen, Z. 2008. Solar Energy Fundamental and Modeling */ |
| 939 |
/* Techniques. Springer, p. 72. */ |
| 940 |
|
| 941 |
double CalcEccentricity() |
| 942 |
{ |
| 943 |
double day_angle; /* Day angle (radians) */ |
| 944 |
double E0; /* Eccentricity */ |
| 945 |
|
| 946 |
/* Calculate day angle */ |
| 947 |
day_angle = (julian_date - 1.0) * (2.0 * PI / 365.0); |
| 948 |
|
| 949 |
/* Calculate eccentricity */ |
| 950 |
E0 = 1.00011 + 0.034221 * cos(day_angle) + 0.00128 * sin(day_angle) |
| 951 |
+ 0.000719 * cos(2.0 * day_angle) + 0.000077 * sin(2.0 * |
| 952 |
day_angle); |
| 953 |
|
| 954 |
return E0; |
| 955 |
} |
| 956 |
|
| 957 |
/* Calculate atmospheric precipitable water content */ |
| 958 |
|
| 959 |
/* Reference: Perez, R., P. Ineichen, R. Seals, J. Michalsky, and R. */ |
| 960 |
/* Stewart. 1990. ìModeling Daylight Availability and */ |
| 961 |
/* Irradiance Components from Direct and Global */ |
| 962 |
/* Irradiance,î Solar Energy 44(5):271-289, Eqn. 3. */ |
| 963 |
|
| 964 |
/* Note: The default surface dew point temperature is 11 deg. C */ |
| 965 |
/* (52 deg. F). Typical values are: */ |
| 966 |
|
| 967 |
/* Celsius Fahrenheit Human Perception */ |
| 968 |
/* > 24 > 75 Extremely uncomfortable */ |
| 969 |
/* 21 - 24 70 - 74 Very humid */ |
| 970 |
/* 18 - 21 65 - 69 Somewhat uncomfortable */ |
| 971 |
/* 16 - 18 60 - 64 OK for most people */ |
| 972 |
/* 13 - 16 55 - 59 Comfortable */ |
| 973 |
/* 10 - 12 50 - 54 Very comfortable */ |
| 974 |
/* < 10 < 49 A bit dry for some */ |
| 975 |
|
| 976 |
double CalcPrecipWater( double dpt ) |
| 977 |
{ return exp(0.07 * dpt - 0.075); } |
| 978 |
|
| 979 |
/* Calculate relative air mass */ |
| 980 |
|
| 981 |
/* Reference: Kasten, F. 1966. "A New Table and Approximation Formula */ |
| 982 |
/* for the Relative Optical Air Mass," Arch. Meteorol. */ |
| 983 |
/* Geophys. Bioklimataol. Ser. B14, pp. 206-233. */ |
| 984 |
|
| 985 |
/* Note: More sophisticated relative air mass models are */ |
| 986 |
/* available, but they differ significantly only for */ |
| 987 |
/* sun zenith angles greater than 80 degrees. */ |
| 988 |
|
| 989 |
double CalcAirMass() |
| 990 |
{ |
| 991 |
return (1.0 / (cos(sun_zenith) + 0.15 * pow(93.885 - |
| 992 |
RadToDeg(sun_zenith), -1.253))); |
| 993 |
} |
| 994 |
|
| 995 |
/* Calculate Perez All-Weather sky patch luminances (modified by GW) */ |
| 996 |
|
| 997 |
/* NOTE: The sky patches centers are determined in accordance with the */ |
| 998 |
/* BRE-IDMP sky luminance measurement procedures. (See for example */ |
| 999 |
/* Mardaljevic, J. 2001. "The BRE-IDMP Dataset: A New Benchmark */ |
| 1000 |
/* for the Validation of Illuminance Prediction Techniques," */ |
| 1001 |
/* Lighting Research & Technology 33(2):117-136.) */ |
| 1002 |
|
| 1003 |
void CalcSkyPatchLumin( float *parr ) |
| 1004 |
{ |
| 1005 |
int i; |
| 1006 |
double aas; /* Sun-sky point azimuthal angle */ |
| 1007 |
double sspa; /* Sun-sky point angle */ |
| 1008 |
double zsa; /* Zenithal sun angle */ |
| 1009 |
|
| 1010 |
for (i = 1; i < nskypatch; i++) |
| 1011 |
{ |
| 1012 |
/* Calculate sun-sky point azimuthal angle */ |
| 1013 |
aas = fabs(rh_pazi[i] - azimuth); |
| 1014 |
|
| 1015 |
/* Calculate zenithal sun angle */ |
| 1016 |
zsa = PI * 0.5 - rh_palt[i]; |
| 1017 |
|
| 1018 |
/* Calculate sun-sky point angle (Equation 8-20) */ |
| 1019 |
sspa = acos(cos(sun_zenith) * cos(zsa) + sin(sun_zenith) * |
| 1020 |
sin(zsa) * cos(aas)); |
| 1021 |
|
| 1022 |
/* Calculate patch luminance */ |
| 1023 |
parr[3*i] = CalcRelLuminance(sspa, zsa); |
| 1024 |
if (parr[3*i] < 0) parr[3*i] = 0; |
| 1025 |
parr[3*i+2] = parr[3*i+1] = parr[3*i]; |
| 1026 |
} |
| 1027 |
} |
