Numerical evaluation of the vibration reduction index for structural joints

The present paper addresses the analysis of structural vibration transmission in the presence of structural joints. The problem is tackled from a numerical point of view, analyzing some scenarios by using finite element models. The numerical results obtained making use of this process are then compared with those evaluated using the EN 12354 standard vibration reduction index concept. It is shown that, even for the simplest cases, the behavior of a structural joint is complex and evidences the frequency dependence. Comparison with results obtained by empirical formulas reveals that those of the standards cannot accurately reproduce the expected behavior, and thus indicate that alternative complementary calculation procedures are required. A simple methodology to estimate the difference between numerical and standard predictions is here proposed allowing the calculation of an adaptation term that makes both approaches converge. This term was found to be solution-dependent, and thus should be evaluated for each structure.

Effects of whole body vibration on strength and jumping performance in volleyball and beach volleyball players

The primary aim of this study was to examine the effects of 6-week strength training with whole body vibration (WBV) on leg strength and jumping performance in volleyball and beach volleyball players. Twenty-three sub-elite male volleyball (VB; n=12) and beach volleyball players (BVB; n=11) aged 21.2±3.0 years were divided into two groups and subjected to 6 weeks of strength training (three one-hour sessions per week): (I) 12 players (6 VB and 6 BVB players) underwent training with WBV (30-40 Hz, 1.7-2.5 mm, 3.0-5.7 g), and (II) 11 players (6 VB and 5 BVB players) underwent traditional strength training. Squat jump (SJ) and countermovement squat jump (CMJ) measurements by the Ergo Tester contact platform and maximum leg press test (1RM) were conducted. Three-factor (2 time x 2 WBV use x 2 discipline) analysis of variance for SJ, CMJ and 1RM revealed a significant time main effect (p<0.001), a WBV use effect (p<0.001) and a discipline effect (p<0.001). Significantly greater improvements in the SJ (p<0.001) and CMJ (p<0.001) and in 1RM (p<0.001) were found in the WBV training groups than in traditional training groups. Significant 3-way interaction effects (training, WBV use, discipline kind) were also found for SJ, CMJ and 1RM (p=0.001, p<0.001, p=0.001, respectively). It can be concluded that implementation of 6-week WBV training in routine practice in volleyball and beach volleyball players increases leg strength more and leads to greater improvement in jump performance than traditional strength training, but greater improvements can be expected in beach volleyball players than in volleyball players.

Front elevation and floor plans for first and second floors, ink and wash on paper, [ca. 1812]

Drawing by Charles Bulfinch of proposed plans for University Hall which were later rejected. Includes sketches of the front exterior view of the University Hall, and separate floor plans for the ground and second floors. Bulfinch designed a ground floor with a chapel and four dining halls each holding 100 students, a second floor with a gallery in the chapel and three rooms over the dining halls for public examinations and meetings of the Corporation and Overseers; and a basement under the halls intended for a kitchen under the dining halls and recitation rooms under the chapel.

Occupational exposure to hand-arm vibration.

Mode of access: Internet.

Relationships between wholebody vibration and morbidity patterns among interstate truck drivers /

"Contract no. CDC-99-74-22."

An experimental and analytical investigation of the vibration noise generation mechanism in truck tires. Interim report.

National Highway Traffic Safety Administration, Office of Heavy Duty Vehicle Research, Washington, D.C.

Proceedings of the International Occupational Hand-Arm Vibration Conference /

Mode of access: Internet.

Passenger response to random vibration in transportation vehicles - literature review. Research report.

Transportation Department of Office of University Research, Washington, D.C.

46th Shock and Vibration Symposium, Royal Inn at the Wharf, San Diego, California, 21-23 October 1975 /

Called Symposium on Shock and Vibration in vols. 2-5.

Ship vibration.

Includes bibliographies.

Shock and vibration environment; [a report bibliography]

"AD-277392."

The random vibration of elastic strings-- theoretical.

"Materials Laboratory, Contract no. AF 33(616)-5426, project no. 7360."

Effect of viscoelastic foundation on forced vibration of loaded rectangular plates

Mode of access: Internet.

Vibration and dissociation coupling behind strong shock waves. Paper presented at the Symposium on Dynamics of Manned Lifting Planetary Entry,

Cover title.

Design of shock and resistant vibration electronic equipment for shipboard use.

NAVSHIPS 900, 185A