xpath('//Asset[Values/Factory/RawMaterial1]') or die('xpath failed.');

foreach ($elements as $element) {
	if (property_exists($element->Values->WareProduction, 'Product')) {
		echo "Skipping ".$element->Values->Standard->Name.PHP_EOL;
	} else {
		echo "Found one! ".$element->Values->Standard->Name.PHP_EOL;
		//print_r($element);
	}
}
print_r($elements);