Accumulator for shaft encoder

Digital accumulator relies almost entirely on integrated circuitry to process the data derived from the outputs of gyro shaft encoder. After the read command is given, the output register collects and stores the data that are on the set output terminals of the up-down counters

Vector field theories in cosmology

Recently proposed theories based on the cosmic presence of a vectorial field are compared and contrasted. In particular the so called Einstein aether theory is discussed in parallel with a recent proposal of a strained space-time theory (Cosmic Defect theory). We show that the latter fits reasonably well the cosmic observed data with only one, or at most two, adjustable parameters, whilst other vector theories use much more. The Newtonian limits are also compared. Finally we show that the CD theory may be considered as a special case of the aether theories, corresponding to a more compact and consistent paradigm.Comment: 19 pages, 1 figure, to appear on Phys. Rev.

A head restraint device for vestibular studies

Head restraint device based on vacuum bladder technique for use in vestibular studie

Data policy and availability supporting global change research, development, and decision-making: An information perspective

An explosion of information has created a crisis for today's information age. It has to be determined how to use the best available information sources, tools, and technology. To do this it is necessary to have leadership at the interagency level to promote a coherent information policy. It is also important to find ways to educate the users of information regarding the tools available to them. Advances in technology resulted in efforts to shift from Disciplinary and Mission-oriented Systems to Decision Support Systems and Personalized Information Systems. One such effort is being made by the Interagency Working Group on Data Management for Global Change (IAWGDMGC). Five federal agencies - the Department of Commerce (DOC), Department of Energy (DOE), National Aeronautics and Space Administration (NASA), National Library of Medicine (NLM), and Department of Defense (DOD) - have an on-going cooperative information management group, CENDI (Commerce, Energy, NASA, NLM, and Defense Information), that is meeting the challenge of coordinating and integrating their information management systems. Although it is beginning to be technically feasible to have a system with text, bibliographic, and numeric data online for the user to manipulate at the user's own workstation, it will require national recognition that the resource investment in such a system is worthwhile, in order to promote its full development. It also requires close cooperation between the producers and users of the information - that is, the research and policy community, and the information community. National resources need to be mobilized in a coordinated manner to move people into the next generation of information support systems

Unification: An international aerospace information opportunity

Science and technology projects are becoming more and more international and interdisciplinary. Other parts of the world, notably Europe, are increasingly powerful players in the aerospace industry. This change has led to the development of various aerospace information initiatives in other countries. With scarce resources in all areas of government and industry, the NASA STI Program is reviewing its current acquisition and exchange practices and policies to factor in the changing requirements and new opportunities within the international community. Current NASA goals and activities are reviewed with a new view toward developing a scenario for establishing an international aerospace database, maintaining compatibility among national aerospace information systems, eliminating duplication of effort, and sharing resources through international cooperation wherever possible

Evaluation of telerobotic systems using an instrumented task board

An instrumented task board was developed at NASA Marshall Space Flight Center (MSFC). An overview of the task board design, and current development status is presented. The task board was originally developed to evaluate operator performance using the Protoflight Manipulator Arm (PFMA) at MSFC. The task board evaluates tasks for Orbital Replacement Unit (ORU), fluid connect and transfers, electrical connect/disconnect, bolt running, and other basic tasks. The instrumented task board measures the 3-D forces and torques placed on the board, determines the robot arm's 3-D position relative to the task board using IR optics, and provides the information in real-time. The PFMA joint input signals can also be measured from a breakout box to evaluate the sensitivity or response of the arm operation to control commands. The data processing system provides the capability for post processing of time-history graphics and plots of the PFMA positions, the operator's actions, and the PFMA servo reactions in addition to real-time force/torque data presentation. The instrumented task board's most promising use is developing benchmarks for NASA centers for comparison and evaluation of telerobotic performance

What Can Altmetric.com Tell Us About Policy Citations of Research? An Analysis of Altmetric.com Data for Research Articles from the University of Sheffield

Background: There is a growing interest in using and analyzing altmetric data for quantifying the impact of research, especially societal impact (Bornmann, 2014, Thelwall et al., 2016, Haunschild and Bornmann, 2017). This study therefore aimed to explore the usefulness of Altmetric.com data as a means of identifying and categorizing the policy impact of research articles from a single center (the University of Sheffield). Method: This study has only included published research articles from authors at the University of Sheffield and indexed in the Altmetric.com database. Altmetric data on policy impact was sourced from Altmetric.com following a data request and included citations up until February 2017. Supplementary Altmetric.com data, including news media, blogs, Mendeley saves, and Wikipedia citations, were also gathered. Results: Altmetric.com data did enable the identification of policy documents that cited relevant articles. In total, 1,463 pieces of published research from authors at the University of Sheffield were found to be cited by between 1 and 13 policy documents. 21 research articles (1%) were listed as being cited in five or more policy documents; 21 (1%) in four policy documents; 50 (3%) in three documents; 186 (13%) in two documents; and 1,185 (81%) in one document. Of those 1,463 outputs, 1,449 (99%) were journal articles, 13 were books, and 1 was a book chapter (less than 1%). The time lag from the publication of the research to its citation in policy documents ranged from 3 months to 31 years. Analysis of the 92 research articles cited in three or more policy documents indicated that the research topics with the greatest policy impact were medicine, dentistry, and health, followed by social science and pure science. The Altmetric.com data enabled an in-depth assessment of the 21 research articles cited in five or more policy documents. However, errors of attribution and designation were found in the Altmetric.com data. These findings might be generalizable to other institutions similar in organizational structure to The University of Sheffield. Conclusion: Within the limitations of the current text-mining system, Altmetric.com can offer important and highly accessible data on the policy impact of an organization’s published research articles, but caution must be exercised when seeking to use this data, especially in terms of providing evidence of policy impact

On the Miura map between the dispersionless KP and dispersionless modified KP hierarchies

We investigate the Miura map between the dispersionless KP and dispersionless modified KP hierarchies. We show that the Miura map is canonical with respect to their bi-Hamiltonian structures. Moreover, inspired by the works of Takasaki and Takebe, the twistor construction of solution structure for the dispersionless modified KP hierarchy is given.Comment: 19 pages, Latex, no figure

Light Deflection, Lensing, and Time Delays from Gravitational Potentials and Fermat's Principle in the Presence of a Cosmological Constant

The contribution of the cosmological constant to the deflection angle and the time delays are derived from the integration of the gravitational potential as well as from Fermat's Principle. The findings are in agreement with recent results using exact solutions to Einstein's equations and reproduce precisely the new $\Lambda$-term in the bending angle and the lens equation. The consequences on time delay expressions are explored. While it is known that $\Lambda$ contributes to the gravitational time delay, it is shown here that a new $\Lambda$-term appears in the geometrical time delay as well. Although these newly derived terms are perhaps small for current observations, they do not cancel out as previously claimed. Moreover, as shown before, at galaxy cluster scale, the $\Lambda$ contribution can be larger than the second-order term in the Einstein deflection angle for several cluster lens systems.Comment: 6 pages, 1 figure, matches version published in PR