Custom Wordpress Query Posts based on meta values - wordpress

Question

I have a simple wordpress query that I need to write as part of a theme I am creating.
I have most of it but need a little push in the right direction to filter the returned results pragmatically based upon a custom meta field of the custom post type.
If the post meta field 'completion date' or 'published date' is equal to or before the current date, put posts into Published Research table.
If the posts meta field 'completion date' or 'published date' is a date ahead of the current date, put the posts into Ongoing Research.
* UPDATED *
Currently I have this:
<div class="container main-content">
<div class="row">
<h1>ONGOING RESEARCH</h1>
<table class="table table-bordered">
<tr>
<th>Type</th>
<th>Title</th>
<th>Summary / Abstract</th>
<th>Keywords</th>
<th>Type of Research</th>
<th>Principle Investigator</th>
<th>Completion Date</th>
</tr>
<?php $wp_query_ongoing = new WP_Query( array( 'post_type' => 'research', 'posts_per_page' => 5, 'order' => 'asc' ) ); ?>
<?php while ( $wp_query_ongoing->have_posts() ) : $wp_query_ongoing->the_post(); //start of the loop ?>
<?php
$post_id = get_the_ID();
$completion_date = get_post_meta( $post_id, "duration_end", true );
$publication_date = get_post_meta( $post_id, "publication_date", true );
?>
<?php if (strtotime($publication_date) >= strtotime("now") || strtotime($completion_date) >= strtotime("now")) { ?>
<tr>
<td><?php echo do_shortcode('[wpuf-meta name="_hidden_type"]' ); ?></td>
<td><?php the_title(); ?></td>
<td>3</td>
<td>4</td>
<td>5</td>
<td>6</td>
<td>
<?php echo do_shortcode('[wpuf-meta name="duration_end"]'); ?>
<?php echo do_shortcode('[wpuf-meta name="publication_date"]'); ?>
</td>
</tr>
<?php } ?>
<?php endwhile; //end of the loop ?>
</table>
<h1>PUBLISHED RESEARCH</h1>
<table class="table table-bordered">
<tr>
<th>Type</th>
<th>Title</th>
<th>Summary / Abstract</th>
<th>Keywords</th>
<th>Author</th>
<th>Type of Research</th>
<th>Open Access</th>
<th>Date Published</th>
</tr>
<?php $wp_query_published = new WP_Query( array( 'post_type' => 'research', 'posts_per_page' => 5, 'order' => 'asc' ) ); ?>
<?php while ( $wp_query_published->have_posts() ) : $wp_query_published->the_post(); //start of the loop ?>
<?php
$post_id = get_the_ID();
$completion_date = get_post_meta( $post_id, "duration_end", true );
$publication_date = get_post_meta( $post_id, "publication_date", true );
?>
<?php if ( strtotime($publication_date) <= strtotime("now") || strtotime($completion_date) <= strtotime("now")){ ?>
<tr>
<td><?php echo do_shortcode('[wpuf-meta name="_hidden_type"]' ); ?></td>
<td><?php the_title(); ?></td>
<td>
<?php echo do_shortcode('[wpuf-meta name="synopsis"]'); ?>
<?php echo do_shortcode('[wpuf-meta name="abstract"]'); ?>
</td>
<td>
<?php echo do_shortcode('[wpuf-meta name="keywords"]'); ?>
<?php
$terms = get_the_terms($post->ID, 'keywords');
foreach ($terms as $keyword) {
$myKeywords[] = $keyword->name;
}
echo implode( ', ', $myKeywords );
$myKeywords = null;
?>
</td>
<td><?php echo do_shortcode('[wpuf-meta name="author"]' ); ?></td>
<td><?php echo do_shortcode('[wpuf-meta name="type_of_research"]'); ?></td>
<td><?php echo do_shortcode('[wpuf-meta name="open_access"]'); ?></td>
<td>
<?php echo do_shortcode('[wpuf-meta name="duration_end"]'); ?>
<?php echo do_shortcode('[wpuf-meta name="publication_date"]'); ?>
</td>
</tr>
<?php } ?>
<?php endwhile; //end of the loop ?>
</table>
* New related question *
Currently the ongoing research table works correctly, only showing posts that have a meta date set somewhere in the future. However, the published table is the correct posts BUT also the posts that should only be in ongoing. ????
I have never worked with dates in php. How can I modify the above code to return posts according to the the date provided in a meta field.
N/B we are not concerned with the posts actual published date, only the date set in a custom meta field.
https://www.dropbox.com/s/0hddjypw9adj9qj/29_alcoholresearchdirectory_browse-research_1-1.png?dl=0
Thanks for any pointers, I have not worked with php and dates.