A Simple Pendulum Determination of the Gravitational Constant

We determined the Newtonian Constant of Gravitation G by interferometrically measuring the change in spacing between two free-hanging pendulum masses caused by the gravitational field from large tungsten source masses. We find a value for G of (6.672 34 +/- 0.000 14) x 10^-11 m^3 kg^-1 s^-2. This value is in good agreement with the 1986 Committee on Data for Science and Technology (CODATA) value of (6.672 59 +/- 0.000 85) x 10^-11 m^3 kg^-1 s^-2 [Rev. Mod. Phys. 59, 1121 (1987)] but differs from some more recent determinations as well as the latest CODATA recommendation of (6.674 28 +/- 0.000 67) x 10^-11 m^3 kg^-1 s^-2 [Rev. Mod. Phys. 80, 633 (2008)].Comment: 10 pages, 2 figure

COMPLIANCE TESTING OF IOWA’S SKID-MOUNTED SIGN DEVICE

A wide variety of traffic control devices are used in work zones, some of which are nont ormally found on the roadside or in the traveled way outsideofthe work zones. These devices are used to enhance the safety of the work zones by controlling the traffic through these areas. Due to the placement of the traffic control devices, the devices themselves may be potentially hazardous to both workers and errant vehicles. The impact performance of many work zone traffic control devices is mainly unknown and to date limited crash testing has been conducted under the criteria of National Cooperative Highway Research Program (NCHRP) Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. The objective of the study was to evaluatethe safety performance of existing skid-mounted sign supports through full- scale crash testing. Two full-scale crash tests were conducted on skid-mounted sign supports to determine their safety performance according to the Test Level 3 (TL-3) criteria set forth in the NCHRP Report No. 350. The safety performancevaluations indicate that these skid-mounted sign supports did not perform satisfactorily in the full-scale crash tests. The results of the crash tests were documented, and conclusions and recommendations pertaining tothe safety performance of the existing work zone traffic control devices were made

SAFETY PERFORMANCE EVALUATION OF THE STEEL-BACKED LOG RAIL

The Coordinated Federal Lands Highways Technology Improvement Program (CTIP) was developed with the purpose of serving the immediate needs of those who design and construct Federal Lands Highways, including Indian Reservation roads, National Park roads and parkways, and forest highways. A wide assortment of guardrails, bridge rails and transitions are being used on roads under the jurisdiction of the National Park Service and other Federal agencies. These guardrails, bridge rails and transitions are intended to blend in with the roadside in order to preserve the visual integrity of the parks and parkways. However, many of them have never been crash tested (1,2). A testing program was developed in order to ensure that the safety hardware used in these areas are safe for the traveling public. The Steel Backed Log Rail was included in the second Federal Highway Administration (FHWA) testing program - Guardrail Testing Program II

On the modelling and testing of a laboratory scale Foucault pendulum as a precursor for the design of a high performance measurement instrument

An integrated study is presented on the dynamic modelling and experimental testing of a mid-length Foucault pendulum with the aim of confirming insights from the literature on the reliable operation of this device and setting markers for future research in which the pendulum may be used for the measurement of relativistic effects due to terrestrial gravity. A tractable nonlinear mathematical model is derived for the dynamics of a practical laboratory Foucault pendulum and its performance with and without parametric excitation, and with coupling to long-axis torsion is investigated numerically for different geographical locations. An experimental pendulum is also tested, with and without parametric excitation, and it is shown that the model closely predicts the general precessional performance of the pendulum, for the case of applied parametric excitation of the length, when responding to the Newtonian rotation of the Earth. Many of the principal inherent performance limitations of Foucault pendulums from the literature have been confirmed and a general prescription for design is evolved, placing the beneficial effect of principal parametric resonance of this inherently nonlinear system in a central mitigating position, along with other assistive means of response moderation such as excitational phase control through electromagnetic pushing, enclosure, and the minimization of seismic and EMC noise. It is also shown, through a supporting analysis and calculation, that although the terrestrial measurement of the Lense-Thirring (LT) precession by means of a Foucault pendulum is certainly still within the realms of possibility, there remains a very challenging increase in resolution capability required, in the order of 2 × 10 9 to be sure of reliable detection, notwithstanding the removal of extraneous motions and interferences. This study sets the scene for a further investigation in the very near future in which these challenges are to be met, so that a new assault can be made on the terrestrial measurement of LT precession

SAFETY PERFORMANCE EVALUATION OF MICHIGAN’S 4X5 PORTABLE SIGN SUPPORT

A wide variety of traffic controlling devices are used in work zones, some of which are not normally found on the roadside or in the traveled way outside of the work zones. These devices are used to enhance the safety of the work zones by controlling the traffic through these areas. Due to the placement of the traffic control devices, the devices themselves may be potentially hazardous to both workers and errant vehicles. The impact performance of many work-zone traffic control devices is mainly unknown and to date limited crash testing has been conducted, under the criteria of National Cooperative Highway Research Program (NCHRP) Report No. 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. The objective of the study was to evaluate the safety performance of Michigan’s existing work-zone traffic control device through full-scale crash testing. A total of two full-scale crash tests were conducted on one 4-ft by 5-ft portable tall-mounted, rigid rectangular-shaped plywood panel sign support to determine its safety performance according to the Test Level 3 (TL-3) criteria set forth in the NCHRP Report No. 350. Neither of impacts on the tall-mounted, rigid panel sign supports resulted in acceptable safety performances. Following the analysis of these crash tests as well as the test results from other testing programs, it has been found that slight variations in design features of the work-zone traffic control devices can lead to very different performance results. Therefore, extreme care should be taken in applying crash test results from one work-zone traffic control device to similar work- zone traffic control devices with slight variations. The results of the crash tests were documented, and conclusions and recommendations pertaining to the safety performance of the existing work-zone traffic control devices were made

SAFETY PERFORMANCE EVALUATION ON THE NEBRASKA TURNED-DOWN APPROACH TERMlNAL SECTION

One full-scale vehicle crash test was conducted on the Nebraska Turned-Down Approach Terminal Section. Test NETD-1 was conducted with a 1984 Dodge Colt weighing 1,887-lbs (test inertial). Impact conditions were 59.0 mph and 0 degrees with a 1.25-ft offset toward the roadway. The test was conducted and reported in accordance with the requirements specified in the Recommended Procedures for the Safety Performance Evaluation of Highway Appurtenances, National Cooperative Highway Research Program (NCHRP) Report No. 230. The safety performance of the Nebraska Turned-Down Approach Terminal Section was determined to be unacceptable according to the NCHRP 230 criteria

SAFETY PERFORMANCE EVALUATION ON THE NEBRASKA TURNED-DOWN APPROACH TERMlNAL SECTION

One full-scale vehicle crash test was conducted on the Nebraska Turned-Down Approach Terminal Section. Test NETD-1 was conducted with a 1984 Dodge Colt weighing 1,887-lbs (test inertial). Impact conditions were 59.0 mph and 0 degrees with a 1.25-ft offset toward the roadway. The test was conducted and reported in accordance with the requirements specified in the Recommended Procedures for the Safety Performance Evaluation of Highway Appurtenances, National Cooperative Highway Research Program (NCHRP) Report No. 230. The safety performance of the Nebraska Turned-Down Approach Terminal Section was determined to be unacceptable according to the NCHRP 230 criteria

FULL-SCALE VEHICLE CRASH TEST ON THE IOWA STEEL TEMPORARY BARRIER RAIL

One full-scale vehicle crash test was conducted on the Iowa Steel Temporary Barrier Rail. Test 15-1 was conducted with at 5,500 pound vehicle at 22.5 degrees and 60.6 mph. The overall test length of the barrier was 200 feet. The barrier was shop fabricated and transported to the test site in 20 foot length sections. The cross-section of the barrier consisted of two stacked steel HP 14x73 (A36) shapes with the edges of the flanges placed back to back and held together by welded steel straps spaced 5 feet on centers. The inside box section between the HP shapes was filled with concrete. The height of the barrier was 29 inches. The 20 foot length sections were bolted together at the test site. The location of the vehicle impact was 100 feet from the end of the barrier installation. This was also the location where two sections were bolted together. The test was evaluated according to the safety criteria in NCHRP 230 and also in the AASHTO guide specifications, performance level 2. The safety performance of the Iowa Steel Temporary Barrier Rail was determined to be satisfactory

Investigation of the Young’s modulus and thermal expansion of amorphous titania-doped tantala films

The current generation of advanced gravitational wave detectors utilize titania-doped tantala/silica multilayer stacks for their mirror coatings. The properties of the low-refractive-index silica are well known; however, in the absence of detailed direct measurements, the material parameters of Young’s modulus and coefficient of thermal expansion (CTE) of the high refractive index material, titania-doped tantala, have been assumed to be equal to values measured for pure tantala coatings. In order to ascertain the true values necessary for thermal noise calculations, we have undertaken measurements of Young’s modulus and CTE through the use of nanoindentation and thermal-bending measurements. The measurements were designed to assess the effects of titania-doping concentration and post-deposition heat-treatment on the measured values in order to evaluate the possibility of optimizing material parameters to further improve thermal noise in the detector. Young’s modulus measurements on pure tantala and 25% and 55% titania-doped tantala show a wide range of values, from 132 to 177 GPa, which are dependent on both titania concentration and heat-treatment. Measurements of CTE give values of (3.9±0.1)×10^(−6)  K^(−1) and (4.9±0.3)×10^(−6)  K^(−1) for 25% and 55% titania-doped tantala, respectively, without dependence on post-deposition heat-treatment