A model of interacting Navier-Stokes singularities

We introduce a model of interacting singularities of Navier-Stokes, named pin\,cons. They follow a Hamiltonian dynamics, obtained by the condition that the velocity field around these singularities obeys locally Navier-Stokes equations. This model can be seen of a generalization of the vorton model of Novikov, that was derived for the Euler equations. When immersed in a regular field, the pin\,cons are further transported and sheared by the regular field, while applying a stress onto the regular field, that becomes dominant at a scale that is smaller than the Kolmogorov length. We apply this model to compute the motion of a dipole of pin\,cons. When the initial relative orientation of the dipole is inside the interval (0, pi/2), a dipole made of pin\,con of same intensity exhibits a transient collapse stage, following a scaling with dipole radius tending to 0 like (tc - t) power 0.63. For long time, the dynamics of the dipole is however repulsive, with both components running away from each other to infinity.Comment: 24 pages 13 figure

Optical interferometer in space

The present design concepts for a Laser Gravitational Wave Observatory in Space are described. Laser heterodyne distance measurements are made between test masses located in three spacecraft separated by roughly 10(exp 6) km. The major technology issues are: the reduction of spurious acceleration noise for the test masses to below 2 x 10(exp -15) cm/sq sec/Hz(0.5) from 10(exp -5) to 10(exp -3) Hz; and the measurement of changes in the difference of the antenna arm lengths to 5 x 10(exp -11) cm/Hz(0.5) from 10(exp -3) to 1 Hz with high reliability. The science objectives are: to measure discrete sinusoidal gravitational wave signals from individual sources with periods of 1 second to 1 day; to measure the stochastic background due to unresolved binaries; and to search for gravitational wave pulses with periods longer than 1 sec from possible exotic sources such as gravitational collapse of very massive objects

Development of a Socketed Foundation for the Midwest Weak Post V1

A socketed foundation was designed and evaluated for use with the Midwest Weak Post (MWP), Version 1. Dynamic component testing was conducted on five different design configurations with varying embedment depths, steel reinforcement, and soil conditions. The low strength of the MWPs limited the force transferred into the foundations and prevented damage in the form of concrete cracking or fracture. Additionally, the lateral movements of the socketed foundations were all within the 1-in. (25-mm) limit established to ensure reuse of the foundations without resetting. The selected design consisted of a 12-in. (305-mm) diameter concrete shaft reinforced with four vertical bars and transverse hoop steel spaced at 6½ in. (165 mm) on center. A 4-in. x 3-in. x ¼-in. (102-mm x 76-mm x 6-mm) steel tube socket was placed in the middle of the shaft. Finally, guidelines were given for the length, or embedment depth, of the foundation based on surrounding soil conditions and risk of frost heave

Cable Median Barrier Failure Analysis and Remediation Phase II

Cable median barrier crashes from a total of 12 states were analyzed. Crash data included scene diagrams, photographs, and field measurements, crash narratives, although the availability of data in each crash varied. Major contributors to penetration crash propensity were identified: diving underride, in which the front end of the vehicle dropped below the bottom cable; prying, in which the vehicle profile caused cable separation or lifting; override; bouncing override, in which the vehicle rebounded after contact with the back slope and bounced over the top of the barrier; system failure, in which one component failure or design failure prevented the cables from adequately engaging the vehicle; and large vehicle crashes, such as tractor trailers, buses, and single-unit trucks into TL-3 systems. Major contributors to rollover were identified: steep median slopes, in which the slope caused unstable bouncing or abrupt changes in slope profiles acted as trip points for the tires; broadside skid, in which the vehicle was skidding with a sideslip angle of nearly 90 degrees prior to contact with the barrier; contact with post, in which the post acted as a trip point; and other factors such as towing trailer units, median anomalies, or with large vehicles such as tractor-trailers, buses, or motor homes. Recommended improvements to cable median barrier systems included: minimum top cable height of 35 in. (890 mm); maximum top cable height of 15 in. (381 mm); minimum of 4 cables supported by posts; higher lateral cable-to-post attachment strength at bottom and lower strength at top; low strong-axis strength post sections; and to eliminate cable entrapment in a vertical slot in the post when initial cable contact occurs at a post location. A summary of factors and how they contributed to penetration, rollover, and severe crash probability is shown in Table 1

BREAKAWAY CONNECTION SYSTEM FOR ROADSIDE USE

A breakaway mounting system for mounting a structure to a fixed support surface has a plurality of elongated mounting members extending generally perpendicular to the support surface. An attachment plate is coupled with the structure to be mounted. The attachment plate has a plurality of apertures formed therein, and each of the mounting members extends through one of the apertures. A plurality of shearing plates are provided. Each shearing plate generally surrounds one of the mounting members and is positioned between the support surface and the attachment plate. Each shearing plate has an upper surface and a lower surface. The area of the shearing plate upper surface is substantially smaller than the area of a lower surface of the attachment plate, and the area of the shearing plate lower surface is substantially smaller than the area of the support surface. A fastener is attached to the mounting member for securing the attachment plate to the support surface. One of the upper surface and the lower surface of each shearing plate forms a shear plane for shearing the associated mounting member when the structure is impacted by a vehicle with sufficient force

Analysis of Existing Work-Zone Sign Supports Using Manual for Assessing Safety Hardware Safety Performance Criteria

Over the years, numerous work-zone, portable sign support systems have been successfully crash tested according to the Test Level 3 safety performance guidelines provided in the National Cooperative Highway Research Program Report 350 and accepted for use along our nation’s highways. For this study, several crashworthy sign support systems were analyzed to predict their safety performance according to the new evaluation criteria provided in the Manual for Assessing Safety Hardware (MASH). More specifically, this analysis was conducted to determine which hardware parameters negatively affect a system’s safety performance. To verify the accuracy of the analysis, eight systems, four with the 2270P pickup truck and four with the 1100C small car, were evaluated according to the MASH criteria. Five out of the eight tested systems failed the MASH criteria, and the other three systems performed in an acceptable manner. As a result of the analysis and verification, several hardware parameters were deemed critical for contributing to system failure under MASH and included sign panel material, top mast height, presence of flags, sign-locking mechanism type, base layout, and system orientation. Flowcharts were developed to assist manufacturers with the design of new sign support systems