function open_popup(url,w,h,resize)
{
    w = new Number(w);
    h = new Number(h);
    var pos_x = ((screen.availWidth - w)/2);
    var pos_y = ((screen.availHeight - (h + 50))/2);
    var ewfeatures = "width="+w+",height="+h+",scrollbars=" + resize + ",resizable=" + resize + ",top="+pos_y+",left="+pos_x;
    var owin = window.open(url,'CentralUniversity',ewfeatures);
    owin.focus();
}