There are a variety of solar thermal collectors available in the market today. These collectors are typically manufactured in diverse countries and have different performance characteristics. For homeowners and commercial solar solution providers, it is important to know how these collectors will perform to ensure maximum return on investment. Therefore, engineers and technicians need to be trained into how different collectors will perform in different locations. In this article, we demonstrate how a Swiss simulations software package called Polysun can be used to accurately determine the performance of a particular system under real operating conditions. To demonstrate the accuracy of the simulations tool, we show performance comparisons with experimental results for different types of flat plate and evacuated tube solar collectors. We also show examples of exercises that can be implemented in an undergraduate course in solar thermal systems. According to our investigations, the thermal performance predicted by Polysun was in close agreement with our experimental measurements. The outcomes of our investigations can help educators make informed decisions regarding teaching solar thermal systems to undergraduates using state-of-the art simulation and visualization tools.

The interbasis expansion of deformed cylindrical 3D harmonic oscillator (HO) wavefunctions in terms of spherical wavefunction bases is introduced. The spatial overlap integral is rewritten in a simplified form and presented in terms of the axis ratio of the deformed nucleus. Deformed nuclear spheroidal shapes are considered, including both quadrupole and hexadecapole deformations. The effect of deformation on the oscillator lengths of deformed 3D-HO, and in turn on the spatial overlap coefficients, is discussed. For the description of the geometrical shape of deformed nuclear systems, the collective and extended Nilsson models for surface parametrization are used.

In the framework of the Relativistic Hartree-Bogoliubov (RHB) mean-field model, a covariant density functional theory (CDFT) is used to systematically investigate the triaxial shape evolution of even-even polonium isotopic chain (N=102-148). Two different effective interactions, i.e. the Density-Dependent Meson-Exchange (DD-ME2) and the new parameter set of Density-Dependent Point-Coupling (DD-PCX) interactions, are utilized in the current study. Besides, the new parameter-free proxy-SU(3) model is used to investigate the ground state shapes of polonium isotopes. CDFT calculations with both parameter sets, predict shape coexistence in the neutron deficient side of polonium isotopic chain, which meets the same prediction of the proxy-SU(3) scheme. The predicted shapes of nuclei are in good agreement with several experimental studies, as well as other theoretical models presented in the current paper. Also, one triaxial ground state is predicted by DD-ME2, DD-PCX, and proxy-SU(3) but for three different nuclei.\\ Different ground state properties like binding energy per nucleon, two-neutron separation energy and proton- neutron- and charge radii are presented in comparison with available experimental data as well as other theoretical models, like the Finite-Range Droplet Model (FRDM), the Infinite Nuclear Matter Model (INMM) and Deformed Relativistic Hartree–Bogoliubov theory in Continuum (DRHBc).

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