window.onload = choosePic;

var adImages = new Array("/_images/logos/bp-logo.jpg","/_images/logos/chevron-logo.jpg","/_images/logos/conocophillips-logo.jpg","/_images/logos/dupont-logo.jpg","/_images/logos/exxonmobil-logo.jpg","/_images/logos/ford-logo.jpg","/_images/logos/general-electric-logo.jpg","/_images/logos/halliburton-logo.jpg","/_images/logos/johnson-controls-inc-logo.jpg","/_images/logos/ppg-logo.jpg","/_images/logos/solutia-logo.jpg");

function rotate() {
      thisAd++;
      if (thisAd == adImages.length) {
         thisAd = 0;
      }
      document.getElementById("adBanner").src = adImages[thisAd];

      setTimeout("rotate()", 3 * 1000);

}

function choosePic() {
      thisAd = Math.floor((Math.random() * adImages.length));
      document.getElementById("adBanner").src = adImages[thisAd];

      rotate();
}