New algorithms for minimum-measure simplices and one-dimensional weighted Voronoi diagrams

We present two new algorithms for finding the minimum-measure simplex determined by a set of n points in R^d for arbitrary d >/= 2. The first algorithm runs in time O(n^d log n) using O(n) space. The only data structure used by this algorithms a stack. The second algorithm runs in time O(n^d) using O(n^2) space, which matches the best known time bounds for this problem in all dimensions and exceeds the previous best space bounds for all d > 3. We also present a new optimal algorithm for building one-dimensional multiplicatively weighted Voronoi diagrams that runs in linear time if the points are already sorted

Constructions of sustainability and spatial planning: the case of Dalton Flatts, County Durham, planning inquiry

This paper explores the constructions of sustainability within a recent land use planning event. The focus is upon the discursive processes employed by key actors and agents in constructing concepts of sustainability during the local planning inquiry into a retail and leisure proposal in the District of Easington, County Durham 'called in' by the Secretary of State for the Environment. It reveals which discourses in particular were employed and discusses their implications. It concludes that sustainability is very much part of a wider political–economic game and that a high degree of social power lies with those participants who are able to utilise the appropriate discursive spaces and concepts; as a result of these factors the rhetoric of the concept of sustainability is generally not being played out within local level planning contexts

From Endings Come Beginnings: Facilitating the Transition from Ending Student to Beginning Practitioner

This presentation was part of the session : Pedagogy: Theories, Approaches24th National Conference on the Beginning Design StudentThe receipt of a degree is momentous; it is at once the end of an academic career and the beginning of practice life. Terminal coursework thus becomes a critical component in successfully preparing students for the classroom-to-office transition. Essential to student preparedness is the ability to critically analyze, synthesize and apply myriad skills and knowledge. Critical thinking and problem solving require an understanding of the intimate relationship between various aspects of theory, research, applied design, and construction methods, materials, and documentation technologies. Equally as important is the development of student confidence and ownership. The lessons offered within a final studio should therefore integrate these elements into a comprehensive process promoting independent exploration, discovery, and application. This approach allows students to make their own connections between design skills and, in turn, transform abstract knowledge into applied understanding. Armed with a holistic comprehension of core fundamentals, emerging practitioners can effectively, efficiently and creatively address the innumerable challenges of professional practice. This paper discusses the application of these ideals into a graduate level, terminal design studio. The exploration of meaning is used to organize the studio around a variety of in-depth urban design projects. Student work is augmented with a reading and discussion seminar that highlights the need for reading, writing and verbal skills in the design process, as well as promotes the continued use of theory and research within professional practice. In total, student design explorations represent successful theory-to-practice applications related to urban landscapes at scales ranging from 1"=40'-0" to 1/8"=1'-0"

An Optimal Algorithm for Higher-Order Voronoi Diagrams in the Plane: The Usefulness of Nondeterminism

We present the first optimal randomized algorithm for constructing the order-$k$ Voronoi diagram of $n$ points in two dimensions. The expected running time is $O(n\log n + nk)$, which improves the previous, two-decades-old result of Ramos (SoCG'99) by a $2^{O(\log^*k)}$ factor. To obtain our result, we (i) use a recent decision-tree technique of Chan and Zheng (SODA'22) in combination with Ramos's cutting construction, to reduce the problem to verifying an order-$k$ Voronoi diagram, and (ii) solve the verification problem by a new divide-and-conquer algorithm using planar-graph separators. We also describe a deterministic algorithm for constructing the $k$-level of $n$ lines in two dimensions in $O(n\log n + nk^{1/3})$ time, and constructing the $k$-level of $n$ planes in three dimensions in $O(n\log n + nk^{3/2})$ time. These time bounds (ignoring the $n\log n$ term) match the current best upper bounds on the combinatorial complexity of the $k$-level. Previously, the same time bound in two dimensions was obtained by Chan (1999) but with randomization.Comment: To appear in SODA 2024. 16 pages, 1 figur

Automated Discovery of porous molecular materials facilitated by characterization of molecular porosity

Porous materials are critical to many industrial sectors, including petrochemicals, energy and water. Traditional porous polymers and zeolites are currently most widely employed within membranes, as adsorbents for separations and storage, and as heterogeneous catalysts. The emerging advanced porous materials, e.g. extended framework materials and molecular porous materials, can boost performance and energy-efficiency of the current technologies because of the unprecedented level of control of their structure and function. The enormous possibilities for tuning these materials by changing their building blocks mean that, in principle, optimally performing materials for a variety of applications can be systematically designed. However, the process of finding a set of optimal structures for a given application could take decades using the traditional materials development approaches. These is a substantial payoff for developing tools and approaches that can accelerate this process. Among advanced porous materials, porous molecular materials are one of the most recent members though they have already attracted significant interest......Programa de Doctorado en Ciencia e Ingeniería de Materiales por la Universidad Carlos III de MadridPresidente: Germán Ignacio Sastre Navarro.- Secretario: Javier Carrasco Rodríguez.- Vocal: Andreas Mavrantonaki

Unlocking the correlation in fluvial outcrops by using a DOM-derived virtual datum: Method description and field tests in the Huesca fluvial fan, Ebro Basin (Spain)

Adequate characterization of depositional architecture is of great importance when studying fluvial outcrops as reservoir analogs. The complex three-dimensional (3D) distribution and lateral and vertical relationships of sandstone bodies require a high degree of stratigraphic control in order to make a proper assessment of the distribution and connectivity of the reservoir facies. This assessment demands the use of reliable correlation datums. Unfortunately, clear marker beds (e.g., ash layers, coal beds, and paleosols) are not always available in fluvial outcrops, and when present, they are often covered by vegetation or debris that prevents their tracking over long distances. A new method to achieve highly accurate and semiautomatic correlations within fluvial digital outcrop models (DOMs) is presented in response to the need for further correlation procedures, especially in the absence of suitable datums. The method is based on the hypothesis that the average depositional paleosurface of a sedimentary system can be represented by a plane at outcrop scale. If this assumption is valid, this plane can be used as a virtual datum to identify along the DOM the sediments that were deposited simultaneously. The method was tested and applied successfully within two kilometer-scale outcrops of the Huesca fluvial fan (Early Miocene, northern Spain), where the virtual datum provided accurate correlations regardless of stratigraphic or topographical complexities. Moreover, all the sedimentary successions of the outcrops could be automatically subdivided into the desired stratigraphic intervals by only moving the virtual datum vertically. These intervals can be subsequently isolated to facilitate the detection of subtle variations and trends of their fluvial properties. Consequently, a virtual datum is the equivalent of having a marker bed crossing the stratigraphic succession of an outcrop at any desired position. The advantages provided by a virtual datum prove to be especially useful in large and topographically complex outcrops that previously could not have been studied with such a high degree of 3D stratigraphic control

The great societal transformations: epigenetic explorations: a transdisciplinary perspective on the evolution of modern knowledge societies ; part I, The Epigenetic Research Program (EPR) - basic building blocks ; part II, 'Great transformations' within modern societies - epigenetic transfer modules (TM)

'Die zwei Artikel in diesem Heft geben eine konzise Übersicht zu einer neuen, transdisziplinären Perspektive für die Analyse 'wissensbasierter Prozesse' innerhalb der unterschiedlichsten Bereiche in den Natur- und Sozialwissenschaften. Dieser neue Approach, der unter dem Namen 'epigenetisches Forschungsprogramm' (ERP) läuft, ermöglicht es, so die zentrale Botschaft dieses Reihenheftes, evolutionäre Entwicklungsmuster der 'sozialen Welt' - in ihren sozio-ökonomischen oder sozio-kulturellen Seiten - einzufangen und zu identifizieren. Dieses neuartige Leistungspotential erschließt sich durch den Aufbau eines konzeptionellen, theoretischen wie modellmäßigen Apparats von transdisziplinärem Geltungsbereich und durch die Differenzierung in zwei Ebenen, nämlich in einen theoretischen, modellbezogenen wie einen generellen anwendungsorientierten transdisziplinären Bereich und in Transfermodule sowie Datenfelder, welche einzelnen Disziplinfeldern zugeordnet werden können. Und hinsichtlich der Aufteilung der zwei Artikel offeriert der erste Teil eine Übersicht zu den einzelnen ERP-Bausteinen und der zweite Teil ein Set an 'Transfermodulen' speziell für die Analyse der Entwicklung moderner Gesellschaften und ihrer so vielfältig gewordenen und weit verteilten Wissensbasen.' (Autorenreferat)'The subsequent two parts give a precise overview of a new and transdisciplinary perspective for the study of 'knowledge based processes' in a wide variety of domains, including natural science fields and social science areas. The new approach which runs under the label of an 'epigenetic research program' (ERP) is able, so the core message, to capture the evolutionary development patterns of the socio-economic and the socio-cultural world. This achievement is brought about through the construction of a conceptual, theoretical and modeling apparatus of sufficient transdisciplinary generality and through the separation of two different levels, namely of ERP-meta-levels on the one hand and ERP-levels of application on the other hand. Meta-level elements are characterized, above all, by their transdisciplinary status, being not linked to any particular type of application domain, whereas building Blocks at application levels are clearly connected with special features in natural science or social science domains. With respect to the set of two consecutive articles, part I presents a general summary of the ERP-perspective and part II is devoted to a set of ERP 'transfer modules' mainly for the evolution of modern societies and their knowledge bases.' (author's abstract)

Laser-driven very high energy electron/photon beam radiation therapy in conjunction with a robotic system

We present a new external-beam radiation therapy system using very-high-energy (VHE) electron/photon beams generated by a centimeter-scale laser plasma accelerator built in a robotic system. Most types of external-beam radiation therapy are delivered using a machine called a medical linear accelerator driven by radio frequency (RF) power amplifiers, producing electron beams with an energy range of 6-20 MeV, in conjunction with modern radiation therapy technologies for effective shaping of three-dimensional dose distributions and spatially accurate dose delivery with imaging verification. However, the limited penetration depth and low quality of the transverse penumbra at such electron beams delivered from the present RF linear accelerators prevent the implementation of advanced modalities in current cancer treatments. These drawbacks can be overcome if the electron energy is increased to above 50 MeV. To overcome the disadvantages of the present RF-based medical accelerators, harnessing recent advancement of laser-driven plasma accelerators capable of producing 1-GeV electron beams in a 1-cm gas cell, we propose a new embodiment of the external-beam radiation therapy robotic system delivering very high-energy electron/photon beams with an energy of 50-250 MeV; it is more compact, less expensive, and has a simpler operation and higher performance in comparison with the current radiation therapy system