3 research outputs found
Shelters for Archaeology: An Architectural Sheltering System for Monuments & Excavation Sites, in the case study of Ancient Eleon in Greece
No full textThe project proposes an architectural sheltering system for transitional use over monuments and excavations sites in the Mediterranean context. The thesis is concerned about the diaspora of archaeological sites and remains in the Mediterranean where many layers of history are partially unearthed and highlighted. Based on a context research, the assignment focuses on Greece's sites for a new excavation -restoration workflow of specialists under better conditions and time periods. A prototype development of a 5x5m grid system that evolved as a deployable folding kit responds to predefined criteria of reversibility, modularity, adaptability and movability. As a case study, the ongoing excavation of Ancient Eleon was selected to present a valid working scenario. Based on the Greek climate, the open-air shelter is based on a repetitive grid of high-point tent modules that form different sheltering schemes and types. This produces a varying architectural result which addresses all sites endangered by weather. The membrane covering along with the deployable aluminum beam profiles are connected with joints. The system is furtherly extended with a series of an adjustable (bars) truss system to span larger trenches etc. As a result, the challenge is for a transitional architecture that can be seen as a type destined for monuments and a product to be further developed.Architecture, Urbanism and Building Sciences | Intectur
Optimal Smoothed Analysis of the Simplex Method
No full textInternational audienceSmoothed analysis is a method for analyzing the performance of algorithms, used especially for those algorithms whose running time in practice is significantly better than what can be proven through worst-case analysis. Spielman and Teng (STOC '01) introduced the smoothed analysis framework of algorithm analysis and applied it to the simplex method. Given an arbitrary linear program with variables and inequality constraints, Spielman and Teng proved that the simplex method runs in time , where σ> 0 is the standard deviation of Gaussian distributed noise added to the original LP data. Spielman and Teng's result was simplified and strengthened over a series of works, with the current strongest upper bound being pivot steps due to Huiberts, Lee and Zhang (STOC '23). We prove that there exists a simplex method whose smoothed complexity is upper bounded by pivot steps. Furthermore, we prove a matching high-probability lower bound of on the combinatorial diameter of the feasible polyhedron after smoothing, on instances using inequality constraints. This lower bound indicates that our algorithm has optimal noise dependence among all simplex methods, up to polylogarithmic factors
An unconditional lower bound for the active-set method in convex quadratic maximization
No full textInternational audienceWe prove that the active-set method needs an exponential number of iterations in the worstcase to maximize a convex quadratic function subject to linear constraints, regardless of the pivot rule used. This substantially improves over the best previously known lower bound [IPCO 2025], which needs objective functions of polynomial degrees ω(log d) in dimension d, to a bound using a convex polynomial of degree 2. In particular, our result firmly resolves the open question [IPCO 2025] of whether a constant degree suffices, and it represents significant progress towards linear objectives, where the active-set method coincides with the simplex method and a lower bound for all pivot rules would constitute a major breakthrough.Our result is based on a novel extended formulation, recursively constructed using deformed products. Its key feature is that it projects onto a polygonal approximation of a parabola while preserving all of its exponentially many vertices. We define a quadratic objective that forces the active-set method to follow the parabolic boundary of this projection, without allowing any shortcuts along chords corresponding to edges of its full-dimensional preimage
