Direct calibration of a true-rms ac voltmeter against a He-free pulsed Josephson standard

Starting from 2019 a new central role is played by quantum standards, owing to the redefined SI, where electrical units are directly linked to the fundamental constants e (elementary charge) and h (Planck constant). Thus, metrologists are nowadays trying to extend the astonishing accuracy attainable in dc measurements to ac and beyond, moving towards calibrations aiming quantum ac voltage generation. Programmable Josephson Voltage Standards are nowadays capable of fulfilling primary metrology requirements only for stepwise-approximated voltage signals up to few hundreds Hz. Pulsed Josephson standards are instead capable of generating arbitrary waveforms at higher frequencies, so are generally called Josephson Arbitrary Waveform Standards (JAWS). Despite of the lower attainable voltage, JAWS are very promising and are the subject of intense research activity. In particular, the capability of generating high spectral purity signals allows high accuracy measurements especially at the low voltage levels (<100 mV rms), which are challenging to be performed by the traditional ac-dc transfer difference using thermal converters. We report in the following about our setup for quantum-based calibrations of a true-rms ac voltmeter with low uncertainty, first results obtained and unsolved issues

Nuclear Power

The world of the twenty first century is an energy consuming society. Due to increasing population and living standards, each year the world requires more energy and new efficient systems for delivering it. Furthermore, the new systems must be inherently safe and environmentally benign. These realities of today's world are among the reasons that lead to serious interest in deploying nuclear power as a sustainable energy source. Today's nuclear reactors are safe and highly efficient energy systems that offer electricity and a multitude of co-generation energy products ranging from potable water to heat for industrial applications. The goal of the book is to show the current state-of-the-art in the covered technical areas as well as to demonstrate how general engineering principles and methods can be applied to nuclear power systems

Electronic capture and analysis of fraudulent behavioral patterns : an application to identity fraud

The objective of this research was to find a transparent and secure solution for mitigating identity fraud and to find the critical factors that determine the solution\u27s acceptance. Identity fraud is identified as a key problem with total losses exceeding fifty two billion dollars (Javelin Strategy and Research 2005). A common denominator in most identity-fraud-prone transactions is the use of a keypad; hence this research focuses on keypad data entry and proposes a biometric solution. Three studies develop, evaluate and investigate the feasibility of this solution. The first study was done in three stages. Stage one investigated the technical feasibility of the biometric keypad, stage two evaluated the keypad under different field conditions and stage three investigated acceptable user parameters. A key shortcoming with current authentication methods is the use of external identifiers that are prone to theft, unlike biometric patterns. A biometric keypad that supplements the present external identifiers was proposed, prototyped and evaluated. The results demonstrated that a biometric keypad can be a feasible medium performance solution. Addition of pressure and higher typing speeds were found to enhance discrimination accuracy while typing patterns were found to vary with elapsed time which led to deterioration in accuracy. The second study interviewed executives with experience in the introduction of new technologies with the objective of identifying and ranking critical factors that are important in the adoption of new biometrics. Performance, ease-of-use and trust-privacy issues were the most cited factors. A biometric acceptance model was formulated and five hypotheses were proposed from these interviews and prior research. Executives rated the keypad\u27s ease-of-use high in comparison to other biometric approaches but were concerned about its accuracy. The third study was a user attitude survey whose objective was to validate the formulated biometric acceptance model and acquire data on acceptable usage parameters. The proposed biometric model was validated and the proposed hypotheses were supported. Acceptable error rates and training times indicated that the biometric keypad would be more complex to engineer. The dissertation concludes by summarizing the contributions and limitations of the three studies followed by several suggestions for future research

Advanced Syncom - Syncom II summary report

Spacecraft systems design, reliability, support equipment, alternate configurations, and radiation instrumentation payload for Syncom I

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

The Deep Space Network

Work accomplished on the Deep Space Network (DSN) was described, including the following topics: supporting research and technology, advanced development and engineering, system implementation, and DSN operations pertaining to mission-independent or multiple-mission development as well as to support of flight projects

NASA Tech Briefs, January 1993

Topics include: Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

Data systems elements technology assessment and system specifications, issue no. 2

The ability to satisfy the objectives of future NASA Office of Applications programs is dependent on technology advances in a number of areas of data systems. The hardware and software technology of end-to-end systems (data processing elements through ground processing, dissemination, and presentation) are examined in terms of state of the art, trends, and projected developments in the 1980 to 1985 timeframe. Capability is considered in terms of elements that are either commercially available or that can be implemented from commercially available components with minimal development