QRDc (United States)

A feasibility study was conducted to demonstrate that vibration control by confinement (VCC) is a viable approach to today’s noise and vibration problems. Two types of structures were examined. First, a finite beam carrying a critical component on one side and subjected to harmonic disturbances on the other side was simulated. In this part of the investigation, the vibration suppression criterion was to minimize vibrations transmitted to the critical component. The VCC approach was compared with current passive methods, such as tuned isolators, vibration absorbers, and two cases of layered damping. As the second example, a plate, resembling the panel section of a car door, was investigated. The plate was subjected to transient and harmonic excitations. The objective was to determine the degree of improvement on the effectiveness of layered damping materials when used in conjunction with VCC. The results of the computer simulation combining VCC with layered damping materials covering 100% and 63% of the plate were of interest in this study. The finite element method was used to model both structures. Results clearly show that VCC can be used as a stand-alone mechanism to suppress or isolate vibrations, or combined with layered damping materials to significantly improve performance. [Work supported jointly by QRDC, Inc., 3M, and the Department of Defense.]

An antiserum was raised to adipokinetic hormone (AKH), a 10-amino-acid-residue peptide found in the arthropod Locusta migratoria. The antiserum demonstrated not only immunocytochemical reaction with some other arthropod species, but also stained many areas of the rat CNS, certain islet cells of the pancreas, and some anterior pituitary cells. The pattern of staining was unlike that for any known rat neuropeptide or hormone. With the antiserum used as the detection system, HPLC and high-voltage electrophoresis yielded two peptides that were purified to homogeneity from rat hypothalamic median eminence. These peptides have unique amino acid compositions, indicating they may be heretofore unknown rat neuropeptides.