Comparison of a Thermal AC Voltage Standard in the 1–30-MHz Frequency Range

This article presents results of a comparison of a traveling ac voltage standard, which was a fused-silica planar multijunction thin-film thermal converter (PMJTC) developed at the National Institute of Standards and Technology (NIST). The ac-dc voltage-transfer difference of the standard was measured at 2 V and selected frequencies from 1-30 MHz against primary thermal ac voltage standards at the Silesian University of Technology, Istituto Nazionale di Ricerca Metrologica, RISE Research Institutes of Sweden, and Trescal A/S Silkeborg

Report on active and planned spacecraft and experiments

Information is presented, concerning active and planned spacecraft and experiments known to the National Space Science Data Center. The information included a wide range of disciplines: astronomy, earth sciences, meteorology, planetary sciences, aeronomy, particles and fields, solar physics, life sciences, and material sciences. These spacecraft projects represented the efforts and funding of individual countries as well as cooperative arrangements among different countries

Report on active and planned spacecraft and experiments

Information concerning active and planned spacecraft and experiments is included. The information covers a wide range of scientific disciplines: astronomy, earth sciences, meteorology, planetary sciences, aeronomy, particles and fields, solar physics, life sciences, and material sciences. These spacecraft projects represent the efforts and fundng of individual countries as well as cooperative arrangements among different countries

A Direct Measurement of the Relativistic Effect of the Gravitational Potential on the Rats of Atomic Clocks Flown in an Aircraft

General relativity predicts that standard clocks placed at differing gravitational potentials will run at different rates. Although experiments confirming the gravitational redshift have been done, they involve frequency and not time, and need not appeal to general relativity for explanation. Therefore, considerable interest exists as to the result of an accurate experiment in which real macroscopic clocks are brought together for comparison before and after separation to differing potentials. This experiment consists of flying an ensemble of atomic clocks in a military aircraft and comparing them before and after flight to another clock ensemble remaining on the ground. The ground ensemble included several Hewlett-Packard Cesium Beam clocks, three Efratom optically pumped Rubidium clocks, and two hydrogen masers. The flying ensemble included at least three Hewlett-Packard Cesium clocks and three Efratom Rubidium clocks. Five of the Cesium clocks were new models delivered with a high beam current option resulting in higher stability than standard models. The clocks were maintained under stringent environmental controls to protect against vibration, magnetic fields, and changes in temperature, pressure, and power supply voltage. Five main flights were ma de, each at approximately 30,000 feet altitude for fifteen hours. The aircraft was continuously tracked by a theodolite calibrated radar which obtained position and velocity measurements for every second of flight. This allowed an accurate calculation of a theoretical prediction to compare to experiment. The flying clocks gained approximately 45 nanoseconds (45 x 10-9 s) with respect to the ground clocks. The normalized results (measured effect divided by predicted effect) and the experimental standard deviations of the mean for each of the five flights were as follows: .999 + .016 .977 + .026 .963 + .013 1.002 + .026 .991 + .037 The result for the entire experiment, with standard deviation of the mean, was .987 ±. .011. The statistically expected standard deviation of the mean based on knowledge of clock quality was approximately .015. Considering this result as well as systematic errors, a final result is established of Measured value/ Predicted value = 0.987 ± .01

Report on active and planned spacecraft and experiments

Information dealing with active and planned spacecraft and experiments known to the National Space Science Data Center (NSSDC) is presented. Included is information concerning a wide range of disciplines: astronomy, earth sciences, meteorology, planetary sciences, aeronomy, particles and fields, solar physics, life sciences, and material sciences. These spacecraft represent the efforts and funding of individual countries, as well as cooperative arrangements among different countries

NCPV FY 1998 Annual Report

This report summarizes the in-house and subcontracted research and development (R and D) activities under the National Center for Photovoltaics (NCPV) from October 1, 1997 through September 30, 1998 (FY 1998). The NCPV is part of the U.S. Department of Energy's (DOE's) National Photovoltaics Program, as described in the DOE National Photovoltaics Program Plan for 1996-2000. The mission of the DOE National Photovoltaics Program is to make PV a significant part of the domestic economy--as an industry and as an energy resource. The two primary goals of the national program are to (1) maintain the U.S. industry's world leadership in research and technology development and (2) help the U.S. industry remain a major, profitable force in the world market. The NCPV provides leadership and support to the national program toward achieving its mission and goals

Research and Technology Objectives and Plans Summary (RTOPS)

The NASA research and technology program for FY 1990 is presented. The summary portions is compiled of each of the RTOPs (Research and Technology Objectives and Plans) used for management review and control of research currently in progress throughout NASA. The RTOP summary is designed to facilitate communication and coordination among concerned technical personnel in government, industry, and universities. The first section containing citations and abstracts of the RTOPs is followed by four indices: Subject; Technical Monitor; Responsible NASA Organization; and RTOP number