Experimental Study on Uplift Capacity of Purlins considering Restraints from Standing Seam Roof Systems

A total of 32 specimens of single-span purlin roof assemblies considering uplift wind load were tested to investigate the structural behavior of cold-formed steel purlins with one flange fastened to standing seam roofs. Failure modes and failure loads of purlins with different parameters were obtained. Full finite element models, incorporate purlins, clips and standing seam roof panels, were developed, and the analysis results were consistent to a high degree with the test results. Using the same element type and material model, the rotational restraint of test roof systems and corresponding influence factors were investigated by finite element models. Finally, using the rotational restraint rigidities and comparing with the test results, the lateral restraint of test roof systems were also studied through a simple finite element model incorporates pure the purlin and presents the rotational restraints and lateral restraints by rotational and lateral springs. It is shown that the standing seam roofs do provide some extent of rotational restraints and lateral restraints to purlins at the connection points, especially for purlins without sag rod

Dynamic dissipative cooling of a mechanical oscillator in strong-coupling optomechanics

Cooling of mesoscopic mechanical resonators represents a primary concern in cavity optomechanics. Here in the strong optomechanical coupling regime, we propose to dynamically control the cavity dissipation, which is able to significantly accelerate the cooling process while strongly suppressing the heating noise. Furthermore, the dynamic control is capable of overcoming quantum backaction and reducing the cooling limit by several orders of magnitude. The dynamic dissipation control provides new insights for tailoring the optomechanical interaction and offers the prospect of exploring macroscopic quantum physics.Comment: accepetd in Physical Review Letter

2-Amino-6-(naphthalen-1-yl)-4-phenyl­pyridine-3-carbonitrile

In the title compound, C22H15N3, the naphthyl ring system makes dihedral angles of 67.40 (2) and 59.80 (3)° with the pyridyl and phenyl rings, respectively. In the crystal, the mol­ecules are connected via inter­molecular N—H⋯N hydrogen bonds, forming a three-dimensional network