Les horloges romaines constituent un vaste corpus archéologique largement sous exploité et en grande partie inédit. Pourtant, ces instruments mériteraient à plus d’un titre une étude approfondie, tant les domaines liés à leur compréhension sont multiples. Le travail effectué ici se veut le plus complet possible et tente d’aborder le maximum de disciplines. Il apporte des informations sur les typologies d’instruments utilisées, sur les dénominations connues, sur le champ lexical utilisé pour désigner ces instruments dans l’Antiquité, mais également sur le contexte historique et géographique dans lequel ils se sont développés. À l’aide de vastes catalogues des éléments archéologiques mais également des mentions épigraphiques et des représentations iconographiques connues, le rôle urbanistique tout autant que symbolique de ces instruments, a pu être mis en avant. Les horloges se trouvaient dans de nombreux endroits publics de la cité, dans les domus les plus riches, mais également dans les jardins des villae, le long des nécropoles, sur certains tombeaux. Certaines pouvaient être emportées en voyage, servir de « boussole » avant l’heure. Monumentales, elles servaient de parure urbaine et d’acte d’évergétisme de choix. À l’intérieur des sanctuaires, elles possédaient une place bien précise. Les résultats de ce travail novateur permettent donc d’envisager les horloges, à l’époque romaine, autrement que comme simples « garde temps ». / Roman clocks form a vast archaeological corpus still under-exploited and for the most part unpublished. However, the subject deserves attention since the fields of activities covered by those instruments are numerous. The purpose of the present archaeological study is to provide comprehension guidelines of all fields of activities covered by the horologia. It brings information on typologies, on known denomination, on lexical fields used in Antiquity, but also on the historical and geographical context of their deployment. Thanks to a huge corpus of the archaeological evidence (563), but also the epigraphical evidences (102) and the iconographical illustration (122) known to us, the urbanistic function of those instruments, as well as the symbolic one, have been put forward. Horologia were everywhere, in cities’ public places, inside the domus of the wealthy, but also in the garden of villae, by the side of necropolis, on some graves. Some were designed for professional or geographical uses (for example in order to be used during long travels, as a compass before the hour). Inside sanctuaries, their uses are not totally understood but they undoubtedly took an active part in the definition of the cult. Some were monumentalised and, as such, were ordered and offered by citizens. To offer a clock was indeed a common act of euergetism in the cities of the Empire.The results of this innovative study which combine archaeology, epigraphy and iconography with astronomy, show that the Roman Horologia were more than simple “time keepers”. They deserve our attention as archaeological objects but also as sociological objects: studying Roman clocks can help us understand our modern conception of time.

Accepted theories of honey bee foraging state that foragers are active at only 1 time of day. It has been shown that a few foragers can be trained to forage at multiple times of day and at many locations. The purpose of the current study was to further investigate the phenomenon of foragers maintaining multiple time-memories. It was found that in small and large sample populations, a minority of foragers could be trained to 2 or more times and places. Within the hive, the foragers that do not fly to the stations also tend to exhibit a persistent time-memory. Remaining experienced foragers cluster at the dance floor at the approach of a training time and remain dispersed throughout the hive at other times. Because foragers can only be recruited from the dance floor, these foragers that stay behind are also exhibiting a time-memory with respect to the proper training time.

abstract: For the last 50 years, oscillator modeling in ranging systems has received considerable attention. Many components in a navigation system, such as the master oscillator driving the receiver system, as well the master oscillator in the transmitting system contribute significantly to timing errors. Algorithms in the navigation processor must be able to predict and compensate such errors to achieve a specified accuracy. While much work has been done on the fundamentals of these problems, the thinking on said problems has not progressed. On the hardware end, the designers of local oscillators focus on synthesized frequency and loop noise bandwidth. This does nothing to mitigate, or reduce frequency stability degradation in band. Similarly, there are not systematic methods to accommodate phase and frequency anomalies such as clock jumps. Phase locked loops are fundamentally control systems, and while control theory has had significant advancement over the last 30 years, the design of timekeeping sources has not advanced beyond classical control. On the software end, single or two state oscillator models are typically embedded in a Kalman Filter to alleviate time errors between the transmitter and receiver clock. Such models are appropriate for short term time accuracy, but insufficient for long term time accuracy. Additionally, flicker frequency noise may be present in oscillators, and it presents mathematical modeling complications. This work proposes novel H∞ control methods to address the shortcomings in the standard design of time-keeping phase locked loops. Such methods allow the designer to address frequency stability degradation as well as high phase/frequency dynamics. Additionally, finite-dimensional approximants of flicker frequency noise that are more representative of the truth system than the tradition Gauss Markov approach are derived. Last, to maintain timing accuracy in a wide variety of operating environments, novel Banks of Adaptive Extended Kalman Filters are used to address both stochastic and dynamic uncertainty. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2020