pan class="co"># Define constraints and bounds for the model</span></span>
<span><span class="va">lower_bounds</span> <span class="op">&lt;-</span> <span class="fu"><a href="https://rdrr.io/r/base/c.html" class="external-link">c</a></span><span class="op">(</span>t1 <span class="op">=</span> <span class="fl">0</span>, t2 <span class="op">=</span> <span class="fl">0</span>, dt <span class="op">=</span> <span class="fl">0</span>, k <span class="op">=</span> <span class="fl">0</span>, beta <span class="op">=</