Reference Systems

The Symposium on Vertical Reference Systems (VeReS) was initiated on the occasion of the XXII General Assembly of the International Union of Geodesy and Geophysics (IUGG), Birmingham 1999, by Professor Dr. Wolfgang Torge, Past President of the International Association of Geodesy (lAG) and representative of lAG to the Pan-American Institute of Geography and History (PAIGH). The idea was to organise another joint symposium of lAG and PAIGH like the previous one held during the XX IUGG General Assembly at Vienna, Austria, in 1991. Good reasons for such a joint symposium were the great success and the ongoing activities of the Project on the South American Geocentric Reference System (Sistema de Referencia Geocentrico para America del Sur, SIRGAS) being sponsored by lAG and PAIGH since 1993. The SIR GAS Project (Working Group I) had presented a continental South American reference frame of 58 stations during the lAG Scientific Assembly at Rio de Janeiro, in 1997. This reference frame was already adopted by several South American countries as the basis for their new national horizontal geodetic datums (SIRGAS Working Group II). To overcome the problems of the heterogeneous vertical (height) datums between the individual countries, SIRGAS had installed its Working Group III "Vertical Datum" in 1997. As the discussion on the unification of vertical reference systems is also going on in lAG and other bodies of science and practice, it was decided to dedicate the symposium to this topic.

The high accuracy of modern astronomical spatial-temporal reference systems has made them considerably complex. This book offers a comprehensive overview of such systems. It begins with a discussion of ‘The Problem of Time’, including recent developments in the art of clock making (e.g., optical clocks) and various time scales. The authors address the definitions and realization of spatial coordinates by reference to remote celestial objects such as quasars. After an extensive treatment of classical equinox-based coordinates, new paradigms for setting up a celestial reference system are introduced that no longer refer to the translational and rotational motion of the Earth. The role of relativity in the definition and realization of such systems is clarified. The topics presented in this book are complemented by exercises (with solutions). The authors offer a series of files, written in Maple, a standard computer algebra system, to help readers get a feel for the various models and orders of magnitude. Beyond astrometry, the main fields of application of high-precision astronomical spatial-temporal reference systems and frames are navigation (GPS, interplanetary spacecraft navigation) and global geodynamics, which provide a high-precision Celestial Reference System and its link to any terrestrial spatial-temporal reference system. Mankind’s urgent environmental questions can only be answered in the context of appropriate reference systems in which both aspects, space and time, are realized with a sufficiently high level of accuracy. This book addresses all those interested in high-precision reference systems and the various techniques (GPS, Very Long Baseline Interferometry, Satellite Laser Ranging, Lunar Laser Ranging) necessary for their realization, including the production and dissemination of time signals.

This volume offers a typology of reference systems across a range of typologically and genetically distinct languages, including English, Mandarin, non-literary varieties of Russian, Chadic languages, and a number of understudied Sino-Russian idiolects. The term 'reference system' designates all functions within the grammatical system of a given language that indicate whether and how the addressee(s) should identify the referents of participants in the proposition. In this book, Zygmunt Frajzyngier explores the major functional domains, subdomains, and individual functions that determine the identification of participants in a given language, and outlines which are the most and least frequently found crosslinguistically. The findings reveal that bare nouns, pronouns, demonstratives and determiners, and coding on the verb ('agreement') have different functions in different languages. The concluding chapters offer explanations for these differences and explore their implications for the theory and methodology of syntactic analysis, for linguistic typology, and for syntactic theories.

Biometrics has moved from using fingerprints to using many methods of assessing human physical and behavioral traits. This guide introduces a new performance evaluation framework designed to offer full coverage of performance evaluation of biometric systems.

This book addresses the problems of mathematical relations between global and classical coordinate references from the practical applications point of view. It presents a large cartographic and numerical information set, which provides great values for practical and academical use based on the classical Albanian coordinative reference (ALB1986/ALB1987). This information is reflected from the positional point of view in the new modern Albanian satellite reference ALBPOS (Albanian Positioning System) or ALBCORS (Albanian Continuous Operation Reference Stations System). The main purpose of this Monograph is to summarize coordinative references applied in Albania in different periods, both classical and modern. Relevant transformation models between traditional/classical reference ALB1986 / ALB1987 and GNSS satellite reference are presented. The book furthermore recommends the mathematical models of the relationship in plan and height, between the Albanian classical reference and the global/European coordinate references (ITRF, EUREF). It serves to professionals involved in fundamental geodetic works as well as all working with GNSS or developing GIS applications.

It is well known that in communicating over randomly time-varying channels, a receiver which performs a channel measurement can make a better decision than one that does not. It is shown that a channel-measuring system improves system performance even when the channel characteristics are fixed only during the present message interval. The randomly time-varying channel studied is that of a Rayleigh fading medium with independently fading mark and space channels whose fading is fixed over one baud interval but is independent from baud to baud. The transmission system is a modified frequency shift keying (FSK) system such that during a portion of a baud interval the mark and space frequencies are always transmitted so as to act as reference signals. For the above system, the following characteristics have been established: (a) Optimum receiver configuration, (b) Optimum ratio alpha of information energy to total signal energy as a function of total available signal-to-noise ratio for a single fading channel, (c) Asymptotic optimum alpha for an M-diversity channel, (d) Error probabilities for (b) and asymptotic error probabilities for (c) for alpha opt as a function of total signal-to-noise ratio. The asymptotic results show that by using reference techniques the order of diversity is effectively doubled. (Author).