Convex Cycle Bases

Convex cycles play a role e.g. in the context of product graphs. We introduce convex cycle bases and describe a polynomial-time algorithm that recognizes whether a given graph has a convex cycle basis and provides an explicit construction in the positive case. Relations between convex cycles bases and other types of cycles bases are discussed. In particular we show that if G has a unique minimal cycle bases, this basis is convex. Furthermore, we characterize a class of graphs with convex cycles bases that includes partial cubes and hence median graphs. (authors' abstract)Series: Research Report Series / Department of Statistics and Mathematic

Distance-regular graphs

This is a survey of distance-regular graphs. We present an introduction to distance-regular graphs for the reader who is unfamiliar with the subject, and then give an overview of some developments in the area of distance-regular graphs since the monograph 'BCN' [Brouwer, A.E., Cohen, A.M., Neumaier, A., Distance-Regular Graphs, Springer-Verlag, Berlin, 1989] was written.Comment: 156 page

Spectrum of the Laplace-Beltrami Operator and the Phase Structure of Causal Dynamical Triangulation

We propose a new method to characterize the different phases observed in the non-perturbative numerical approach to quantum gravity known as Causal Dynamical Triangulation. The method is based on the analysis of the eigenvalues and the eigenvectors of the Laplace-Beltrami operator computed on the triangulations: it generalizes previous works based on the analysis of diffusive processes and proves capable of providing more detailed information on the geometric properties of the triangulations. In particular, we apply the method to the analysis of spatial slices, showing that the different phases can be characterized by a new order parameter related to the presence or absence of a gap in the spectrum of the Laplace-Beltrami operator, and deriving an effective dimensionality of the slices at the different scales. We also propose quantities derived from the spectrum that could be used to monitor the running to the continuum limit around a suitable critical point in the phase diagram, if any is found.Comment: 21 pages, 26 figures, 2 table

Performance of the upgraded Orroral laser ranging system

The topics discussed include the following: upgrade arrangements, system prior to 1991, elements of the upgrade, laser performance, timing system performance, pass productivity, system precision, system accuracy, telescope pointing and future upgrades and extensions

Acceleration and interannual variability of creep rates in mountain permafrost landforms (rock glacier velocities) in the European Alps in 1995–2022

Cryospheric long-term timeseries get increasingly important. To document climate-related effects on long-term viscous creep of ice-rich mountain permafrost, we investigated timeseries (1995–2022) of geodetically-derived Rock Glacier Velocity (RGV), i.e. spatially averaged interannual velocity timeseries related to a rock glacier (RG) unit or part of it. We considered 50 RGV from 43 RGs spatially covering the entire European Alps. Eight of these RGs are destabilized. Results show that RGV are distinctly variable ranging from 0.04 to 6.23 m a$^{−1}$. Acceleration and deceleration at many RGs are highly correlated with similar behaviour over 2.5 decades for 15 timeseries. In addition to a general long-term, warming-induced trend of increasing velocities, three main phases of distinct acceleration (2000–2004, 2008–2015, 2018–2020), interrupted by deceleration or steady state conditions, were identified. The evolution is attributed to climate forcing and underlines the significance of RGV as a product of the Essential Climate Variable (ECV) permafrost. We show that RGV data are valuable as climate indicators, but such data should always be assessed critically considering changing local factors (geomorphic, thermal, hydrologic) and monitoring approaches. To extract a climate signal, larger RGV ensembles should be analysed. Criteria for selecting new RGV-sites are proposed

Active Faulting in the Northern Walker Lane and Post-Earthquake Reconnaissance in the Central Walker Lane, Nevada and Eastern California

The Walker Lane is a region of diverse tectonic activity situated along the Pacific-North American plate boundary. Unmapped and under characterized faults within the northern Walker Lane are associated with large uncertainties in the location and frequency of potential earthquakes in the greater Reno, Nevada metropolitan area. Mapping of primary and secondary earthquake features in post-event studies help understand the location of faulting and amount of damage associated with earthquakes in the central Walker Lane. Two fault systems in the northern Walker Lane are the Petersen Mountain fault located in the North Valleys region of Reno, and the Bonham Ranch fault in the Smoke Creek Desert of Pleistocene Lake Lahontan in the northern Walker Lane. A paleoseismic trench was excavated across the Petersen Mountain fault to document evidence for faulting and determine the timing of earthquake events. Optically stimulated luminescence dating methods were applied to faulted alluvial fan deposits exposed in the trench. For the Bonham Ranch fault, Uncrewed Aerial Vehicle (UAV) flight surveys were conducted in three locations to investigate differences between topographic scarps formed by tectonic displacement and shoreline processes. Cross cutting relations between the different scarp types combined with stratigraphic observations from outcrops were used to assess the timing of tectonic displacement across the fault. Additionally, UAV surveys were conducted during post-earthquake rapid response reconnaissance in the central Walker Lane immediately following the 15 May 2020 M6.4 Monte Cristo, Nevada and 8 July 2021 M6.0 Antelope Valley, California earthquakes. The drone flights assisted ground crews in determining where to look for surface rupture, earthquake secondary effects, and associated damage. These data provided insight into the amount and style of surface deformation immediately following the earthquake events, and the locations of faulting in the central Walker Lane. These studies help answer questions pertaining to the locations and effects of earthquakes in these regions. By incorporating UAV technology into tectonic studies, hi-res aerial images for mapping and Structure From Motion models can be created, and result in a permanent archive of post-earthquake surface damage as well as provide means to measure paleo and modern surface rupture offsets applicable to seismic hazard characterization

Turning data into information: assessing and reporting GIS metadata integrity using integrated computing technologies

A Geographic Information System (GIS) serves as the tangible and intangible means by which spatially related phenomena can be created, analyzed and rendered. GIS metadata serves as the formal framework to catalog information about a GIS data set. Metadata is independent of the encoded spatial and attribute information. GIS metadata is a subset of electronic metadata which catalogs electronic resources such as web pages and software applications. However, GIS metadata is inherently different than electronic media because each metadata file can be applied to a spatial component that is not implicit with other forms of metadata. Using open source technologies such as R, Perl and PHP, metadata information for large GIS data sets (thousands of layers) can be gleaned quickly and more efficiently than the human element. In doing so, metrics to express the integrity of both the metadata and GIS data can be captured, displayed and compared for use in the decision making process. Supervised and unsupervised techniques allow users and computer algorithms to explore unseen trends about the GIS data not obvious to the human component. The validity of these analyses was tested using a Technology Acceptance Model (TAM). Responses from 40 GIS professionals about the results of this methodology were captured to find a relationship between this technology’s Perceived Ease of Use, Perceived Usefulness, Attitude Towards Using and the Intention to Further use this technology

Block-type military balneum in Timacum Minus: Its spatial arrangement, social impacts, and architectural analogies

Prilikom arheoloških istraživanja u periodu 1975-1980. otkriveni su ostaci rimskog kupatila na oko sto metara severoistočno od kastela. Prema koncepciji prostornog plana objekta, jasno se izdvajaju dva dela - istočni i zapadni. Analizom konstruktivnih elemenata tih delova utvrđeno je da zapadni deo predstavlja stariju fazu a istočni deo mlađu fazu rimskog kupatila. Zapadni deo kupatila podeljen je unutrašnjim poprečnim i podužnim zidom na četiri prostorije koje su opremljene kadama za kupanje. Tri prostorije imale su hipokauste, a u četvrtoj nisu postojale instalacije za grejanje. TA poslednja prostorija imala je funkciju frigidarijuma, dok su preostale tri imale funkciju toplih prostorija (kaldarijuma, tepidarijuma i, izvesno, lakonikuma). Istočni deo kupatila sastoji se od jedne veće prostorije u kojoj nije bilo kada za kupanje ili instalacija za grejanje. U njenim ostacima zatečeno je više fragmenata fresaka, stakla, krovnog pokrivača i izgorelih drvenih konstrukcija. Prema prostornom odnosu između ove prostorije i starijeg zapadnog dela utvrđeno je da je ona morala imati funkciju apoditerijuma. Softverskom analizom unutrašnjeg prostornog sklopa rimskog kupatila ispitivan je uticaj arhitekture na socijalno ponašanje korisnika. Posebno su analizirane vizure, povezanost, vizuelna integracija i mogućnost vizuelnog definisanja najkraćeg direktnog puta pri komuniciranju između pojedinačnih prostorija. Uticaj ovih kategorija na neposrednu fizičku i vizuelnu komunikaciju ukazuje na to da se ovaj objekat u svom zapadnom delu odlikovao niskom vrednošću socijalne povezanosti. Istočni deo rimskog kupatila (apoditerijum) karakteriše veći uticaj na socijalizaciju korisnika. Generalno, stepen integracije pojedinačnih prostora u celinu jako je Mali, što upućuje na to da je i stepen socijalizacije unutar rimskog kupatila na Timacum Minus-u bio veoma nizak. Prostorni odnos između pojedinačnih prostorija u starijem zapadnom delu određuje pripadnost plana prvobitnog rešenja tipu blokovskog sklopa rimskih kupatila. Prema površini koju zauzima, stepenu unutrašnje dekorativnosti i socijalne interakcije koju prostor objekta definiše, rimsko kupatilo u Timacum Minus-u definiše se kao balneum. Prostorna koncepcija ovog rimskog kupatila jedinstvena je na teritoriji Srbije prema specifičnoj sažetosti rešenja blokovskog sklopa. Na tlu jugoistočne Evrope postoji Mali broj sličnih rešenja, u kojima se mogu prepoznati i izvesne razlike u arhitektonskim detaljima. Najveći broj sličnih rešenja blokovskog tipa balneuma registrovan je kod vila rustika na području gornje Rajne i gornjeg Dunava (tj. antičke Germanije Superior i Zapadne Recije).The remains of a Roman bath are situated northeast of the remains of the Timacum Minus castrum. The discovered building is small in size, with a total area of about 242 m². According to the specific layout of rooms, with a reduced spatial organization of its plan, the building belongs to the reduced block-type of military small baths - balneae. In the territory of Serbia, no military balneae of this type have been discovered so far, which are otherwise common for border areas throughout the Roman Empire. The specific spatial relationship between the individual rooms and the characteristic building forms registered in the building plan indicate that the origin of the architecture of the military balneum in Timacum Minus should be associated with the Roman architecture of the balneae that belong to the villae rusticae in Central Europe

On the popularization of digital close-range photogrammetry: a handbook for new users.

Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Γεωπληροφορική