function get_random()
      {
          file_names = new Array("01.jpg",
                                 "02.jpg",
                                 "03.jpg",
                                 "04.jpg",
                                 "05.jpg",
                                 "06.jpg",
                                 "07.jpg",
                                 "08.jpg",
                                 "09.jpg",
                                 "10.jpg",
                                 "11.jpg",
                                 "12.jpg",
                                 "13.jpg",
                                 "14.jpg",
                                 "15.jpg",
                                 "16.jpg",
                                 "17.jpg",
                                 "18.jpg",
                                 "19.jpg",
                                 "20.jpg",
                                 "21.jpg",
                                 "22.jpg",
                                 "23.jpg",
                                 "24.jpg",
                                 "25.jpg",
                                 "26.jpg",
                                 "27.jpg",
                                 "28.jpg",
                                 "29.jpg",
                                 "30.jpg",
                                 "31.jpg",
                                 "32.jpg",
                                 "33.jpg",
                                 "34.jpg",
                                 "35.jpg"
                                 );

          i = Math.floor(Math.random()*file_names.length);
          document.write('<img src="/images/flash/' + file_names[i] + '">');
      }

      function get_random_promo()
      {
          // define file names
          file_names = new Array("airport.gif",
                                 "blower.gif",
                                 "chipcooling.gif",
                                 "lung.gif",
                                 "oven.gif",
                                 "sparpipe.gif"
                                 );

          // define titles
          titles = new Array("Airport Ventilation Example",
                             "Blower Example",
                             "Electronic Cooling Example",
                             "Lung Example",
                             "Oven Heating Example",
                             "Spar VIM Example"
                             );

          // define captions
          captions = new Array("In tempered climates, such as in Caribbean Islands, it is desirable to design an airport such that it is naturally ventilated. This will reduce or eliminate the need for expensive air conditioning. The design must, however, avoid bringing the airplane fumes into the terminal.",
                               "The unsteady motion of the flow in a blower caused by the blade passage is a significant source of noise in a car\'s HVAC system.  Understanding and eventual reduction of this noise leads to better passenger experience.",
                               "As air flows through a Cross-cut heat sink, it absorbs the heat generated by the electronic chip attached to the bottom of the heat sink. Cross-cut heat sinks easily accommodate changes in flow direction.",
                               "Lung starts with one pipe near the throat. This pipe splits into two smaller pipes, which in turn split into two and so on, until the pipes are small enough to allow exchange of carbon dioxide and oxygen via direct molecular diffusion.",
                               "Ovens heat up the food by its circulating hot air as well as direct radiation from its heating elements. Active control of the heating elements keeps the temperature of the chamber nearly constant and provides uniform heating.",
                               "Spars are floating oil platforms that experience vortex-induced motions (VIM) in the presence of strong currents.  Helical strakes are used to break the coherent vortex structures, reducing the VIM response."
                               );

          // let javascript generate a random number
          i = Math.floor(Math.random()*file_names.length);

          // construct HTML code for the promo section
          document.write('<img src="/images/promo/' + file_names[i] + '" />');
          document.write('<!-- begin image caption title -->');
          document.write('<h6>' + titles[i] + '</h6>');
          document.write('<!-- end image caption title -->');
          document.write('<!-- begin image caption -->');
          document.write('<p>' + captions[i] + '</p>');
      }