Replace

my $url = $link->url_abs;
my $filename = URI::Escape::uri_escape( $link->url_abs->path );
$filename =~ s[^.+/][];
[download]

with

my $base = "http://www.xxxx.com/programs_results/pdf/";

my $filename = join '', $link->rel($base)->path_segments();
[download]