This dissertation presents a novel satellite timekeeping system which does not require on-board atomic clocks as used by existing navigation satellite systems such as GPS, GLONASS or the planned GALILEO system. This concept is differentiated by the employment of a synchronization framework combined with lightweight steerable on-board clocks which act as transponders re-broadcasting the precise time remotely provided by the time synchronization network located on the ground. This allows the system to operate optimally when satellites are in direct contact with the ground station, making it suitable for a system like the Japanese Quasi-Zenith Satellite System, QZSS. Low satellite mass and low satellite manufacturing and launch cost are significant advantages of this novel system. Two possible implementations of the time synchronization network for QZSS are presented. Additionally, the problem of satellite communication interruption is analyzed and a solution is presented. Finally a positioning and timing quality analysis, aimed to provide understanding of the actual timing quality requirements for QZSS, is presented.

This dissertation presents a novel satellite timekeeping system which does not require on-board atomic clocks as used by existing navigation satellite systems such as GPS, GLONASS or the planned GALILEO system. This concept is differentiated by the employment of a synchronization framework combined with lightweight steerable on-board clocks which act as transponders re-broadcasting the precise time remotely provided by the time synchronization network located on the ground. This allows the system to operate optimally when satellites are in direct contact with the ground station, making it suitable for a system like the Japanese Quasi-Zenith Satellite System, QZSS. Low satellite mass and low satellite manufacturing and launch cost are significant advantages of this novel system. Two possible implementations of the time synchronization network for QZSS are presented. Additionally, the problem of satellite communication interruption is analyzed and a solution is presented. Finally a positioning and timing quality analysis, aimed to provide understanding of the actual timing quality requirements for QZSS, is presented.

No description available.

<p>Trajectory formation is an important quality of human movement wherein the analysis of its kinematic structure often permits inferences regarding the underlying sensorimotor organization. The studies reported herein aimed to reveal how task-specific encoding of saccades contribute to two movement models. We first examined saccades for changes in the evidence for online spatial corrections in response to different instances of visual tracking. Results from our first study indicated the sensorimotor operations associated with making timed series responses permitted unhindered operation of online corrections in predictive saccades. These saccades imposed a demand on spatial working memory without suffering diminished corrections typical of single delayed memory-guided saccades. Next, we queried the role of ventral stream visuomotor processing, as well as the contribution of basic stimulus features to explaining known modulations of online saccadic corrections. Our results are consistent with the explanation that ventral stream contribution to target metrics influence trajectory kinematics, but did not induce diminished online corrections if vision of that illusory target was available at saccade onset. Using another movement task, we examined how different saccadic tracking behaviours dissociated the contribution of various sensorimotor operations involved in oculomotor preparation and execution to eye-hand coupling. By observing changes in manual trajectory in an oculo-manual task, we contrasted the effects of saccadic tracking in predictive and reactive modes, overt and covert, horizontal and vertical, spatially congruent or perpendicular axes of primary motion relative to eye-hand coupling. From these data we concluded that saccadic encoding induced execution-dependent coupling, and optionally motor planning-dependent coupling when task constraints specified temporal synchrony between eye and hand movements. Moreover, eventual motor execution was a prerequisite for the emergence of oculomotor planning-dependent coupling effects. This implied no apparent contribution to the coupling dynamic as an exclusive function of shifts in the spatial allocation of attention without oculomotor output.</p> / Doctor of Philosophy (PhD)

Ancient settlements in Oman are frequently found where crops can be cultivated with groundwater distributed to fields by gravity flow. These irrigation systems are called aflāj (s. falaj), and they are still pivotal to community life: in 1997 over 3000 such systems were still in use. The allocation of falaj water among farmers traditionally depended on the use of the sun and the stars to track the passage of time. This practice, and particularly the use of stars, is disappearing rapidly: the availability of watches since c. 1970 means that there is now little technical reason to use the stars. The study records fast disappearing information on the ethnography of agricultural communities in northern Oman and, in particular, on the use of stars. It aims to identify the stars used and record the methods of stargazing in sufficient detail that the systems could be replicated if all local knowledge were lost. It also aims to raise awareness and improve the understanding of the significance of the traditional use of the stars in irrigated agriculture. This aspect of the cultural heritage of the region has not been written about previously in such detail. The research questions concern how, where and why stars are still used. There are several documents on falaj building and organisation in Oman, but relatively little on telling the time, and much less on the stars than on the use of the sun. The available documents were reviewed, but the main source for this study is data collected in the field, interviewing falaj managers and stargazers and watching the stars with them. Field work was carried out in different seasons since the stars used vary through the year. International experts were consulted on various aspects of the work, including Daniel Varisco on folk astronomy and Paul Kunitzsch on star names. The study focuses on five settlements where stars are used to this day. These are Qarya Beni Subh (Qarya), close to the mountains near the town of Al Hamra in the Interior Region; Al Fath, Zahib, Sudayra and Barzaman near the towns of Mudaybi and Sinaw in the Eastern Region. Additional information was obtained from a few other places for comparison, and during the course of the research it was found that only about eight of three thousand active falaj communities still use stars for time keeping. The methods of stargazing are given in detail, together with the names of the stars in Oman and their international classification where possible. It was found that the number of stars, the stars used, and their names in Oman vary from place to place. The time that each star represents is more variable than expected from the difference in length of night during the year. The stars used for falaj purposes are compared with those used in the region for navigation and with the stations of the moon of the Islamic calendar, but no evidence of any link between them was identified. On the basis of the history of falaj systems in Oman, the star names and the stars used, at least two of which are from the pre-Islamic Bedu tradition, it is concluded that the system of stargazing for timing water dates from pre-Islamic times, before the introduction of the stations of the moon. The main reason for the continued use of stars by a few communities, even though wristwatches are now widely available, is thought to be adherence to tradition both for its own sake and to avoid disputes over the sharing of water. It is considered unlikely that this ancient practice will survive more than 10 or 20 years unless the younger generation takes an interest in learning, and putting into practice, the traditions of their forefathers.

This thesis deals with the design and realization of wireless electronic timer for fire sport. The first part of thesis provides an analysis of the given problems and all component parts of the system which are needed for time measurement in the fire sport. The principal aim of thesis was to create a wireless electronic timer for simultaneous measurement of up to four lanes. The designed measuring system is equipped with a large LED display to show the final time. Targets and starting pistols are wirelessly connected with the main unit of timer with using a communication platform IQRF. The whole device is structural designed to the handling was as simple as possible.

This thesis describes the design, development and realization of a wireless electronic timer for use in firesport. Specification of the final product is built with regard to versatility, ease of use and low acquisition costs. Commercial products have been compared as inspiration for this work. Requirements of the timer are based on the rules of firesport disciplines, where the timer can be used. It consists of a base station that can be accompanied for additional elements used to starting, splits capturing and stopping. An independent communication module has been created to ensure wireless connection. Libraries for comfort work with the module, support for USB bus and reliable protocol for wireless transmission have been implemented.

This dissertation asks why the system of time measurement set up towards the end of the nineteenth century took the form that it did. The answer is partially dependant on the advent of new technologies such as railways, steamships, and telegraphs. However, instead of focusing on a teleological story of technological progress, this dissertation derives its answer by examining the social, political, and cultural context of the individuals involved. The dissertation uses the 1884 International Meridian Conference as a case study to suggest that time reform was driven by professional context more than by technological imperatives or national interest. Astronomers and engineers came to the conference with very different visions for modern timekeeping. Using a constructivist lens, this dissertation examines the decision-laden process by which temporal knowledge was constructed. Questions about the very nature of accurate time was at the heart of the debate: was time a public good, a commodity, or a specialized tool? The answers to these questions depended heavily on one’s profession, and as a result the conference, directed by astronomers who preferred time as a specialized tool, rejected standard time as a broad reformation of civil timekeeping for the public. The process of construction continued after the conference as well, as the universality of standard time became wrapped up with the heightened accuracy required by specialized astronomical time. Entrepreneurs latched on to this, selling accurate time as a desirable symbol of modernity, while at the same time large numbers of people continued to use older timekeeping methods that were more convenient. New timekeeping methods did not sweep aside the old, leaving timekeeping a more complex, rather than a simplified, process. The standard time system which emerged from this complexity was far from inevitable, and in fact remained largely incomplete. / Thesis / Doctor of Philosophy (PhD) / This dissertation asks why the system of time measurement set up towards the end of the nineteenth century took the form that it did. While partially dependent on new technologies such as railways and telegraphs, timekeeping was shaped more directly by the cultural context of the individuals involved. The dissertation uses the 1884 International Meridian Conference as a case study to suggest that time reform was driven by professional norms more than by national interest or changes in technology. Astronomers and engineers came to the conference with very different visions for modern timekeeping. Indeed, questions about the very nature of accurate time was at the heart of the debate: was time a public good, a commodity, or a specialized tool? The answers to these questions depended heavily on one’s profession, and as a result the standard time system that emerged was far from inevitable, and in fact remained incomplete.

The thesis seeks to reveal, through the use of numerous case studies, the timekeeping processes that helped to make New Zealand. Whilst the period under review covers primarily the period 1840 to 1868 there is also a discussion of the emergence of clock time in thirteenth century Britain and Europe and its development through to the late nineteenth century. This is because the settlers‟ apprehension of time and their use of clocks and watches had evolved over the preceding centuries. The importance of reliable time was recognised by the Church from the medieval period but as ownership of public and private clocks proliferated the decentralisation of clock time commenced. Clock time commanded the lives of people and imprinted itself through the inculcation of such notions as punctuality and productivity. Better clocks brought a new emphasis to workplace efficiency underpinning the belief that time was money and facilitated the efficient coordination of Land, Labour and Capital. The discovery of New Zealand required timekeeping at sea. The achievements of James Cook, underpinned by improved chronometers, facilitated the large-scale British colonisation of New Zealand and seldom brought respite from the rule of time. Once on land, the settlers looked to establish a temporal order similar to Britain. The challenge to establish and disseminate the „true‟ local time within communities led to the setting up of observatories and the use of public clocks, time ball stations, bells and guns to signal clock time. The myriad of local times was not a problem at first but once the telegraph began to link communities they hindered its optimal efficiency. This led to the introduction of „telegraph time‟ in early 1868, dual time systems in communities using the telegraph, and public debate. Whilst most provinces accepted the new clock time, Otago saw it as an affront to their community‟s autonomy and identity. The province challenged the imposition of telegraph time, instigated a Parliamentary debate, and argued for the introduction of a common New Zealand time. Parliament‟s 1868 decision was a triumph for convenience and economic rationality over tradition and local identity. New Zealand was the first country entirely to abandon local times and regulate its time in relation to Greenwich mean time.

No description available.