Form and Data - from linear Calculus to cybernetic Computation and Interaction

Digital architecture developed in the 1960s and, supported by CAAD the 1990s, has created the path towards an architecture produced by computer and architect in a mutual relationship. The evolution of architecture since the 1970s led to the beginning of the first digital turn in the 1990s, and subsequently to the emergence of new typologies of buildings, architects and design tools; atom-based, bit-based (virtual) [1], and cyber-physical as a combination of both. The paper provides an insight into historical foundations of CAAD insofar as it engages with complexity in mechanics, geometry, and space between the 1600s and 1950s. I will address a selection of principles discovered, and mechanisms invented before computer-aided-architectural-design; those include the typewriter, the Cartesian grid and a pre-cyber-physical system by Hermann von Helmholtz. The paper concludes with a summary and an outlook to the future of CAAD challenged by the variety of correlations of disparate data sets

Semi-flexible Additive Manufacturing Materials for Modularization Purposes - A modular assembly proposal for a foam edge-based spatial framework

This paper introduces a series of design and fabrication tests directed towards the use of bendable 3D printing materials in order to simplify a foam bubble-based geometry as a frame structure for modular assembly. The aspiration to reference a spittlebug's bubble cocoon in nature for a light installation in the urban context was integrated into a computational workflow conditioning light-weight, material-, and cost savings along with assembly-simplicity. Firstly, before elaborating on the project motivation and background in foam structures and applications of 3D-printed thermoplastic polyurethane (TPU) material, this paper describes the physical nature of bubble foams in its relevant aspects. Subsequently this is implemented into the parametric design process for an optimized foam structure with Grasshopper clarifying the need for flexible materials to enhance modular feasibility. Following, the additive manufacturing iterations of the digitally designed node components with TPU are presented and evaluated. Finally, after the test assembly of both components is depicted, this paper assesses the divergence between natural foams and the case study structure with respect to self-organizing behavior

Fit to Electroweak Precision Data

A brief review of electroweak precision data from LEP, SLC, the Tevatron, and low energies is presented. The global fit to all data including the most recent results on the masses of the top quark and the W boson reinforces the preference for a relatively light Higgs boson. I will also give an outlook on future developments at the Tevatron Run II, CEBAF, the LHC, and the ILC.Comment: 4 pages, presented at the 2006 Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2006), Rio Grande, Puerto Rico, May 30 -- June 3, 200

Bond angle distribution in amorphous germania and silica

The distribution of Ge-O-Ge and Si-O-Si bond angles alpha in amorphous germania and silica is re-determined on the basis of diffraction experiments. The bond angle alpha joining adjacent tetrahedra is the central parameter of any continuous random network description (CRN) of these glasses. New high energy photon diffraction experiments on amorphous germania (at photon energies of 97 and 149 keV) are presented, covering the momentum transfer 0.6-33.5 AA^{-1}. In photon diffraction experiments on GeO2 the contribution of the OO pairs is very small. To obtain a similar information for amorphous SiO2, high energy photon diffraction experiments have been combined with neutron diffraction data on amorphous silica in order to eliminate the OO- partial structure factor. With this technique it is shown that the Si-O-Si angle distribution is fairly narrow (sigma=7.5 degree) and in fact comparable in width to the Ge-O-Ge angle distribution (sigma=8.3 degree), a result which differs from current opinion. The narrower distribution found in this study are in much better agreement to the determinations based on 29Si-MAS-NMR. Among the various models relating the chemical shift to the bond angle, best agreement is found with those models based on the secant model. Sharp components in the bond angle distribution can be excluded within the reached real space resolution of 0.09 AA.Comment: 12 pages LATEX, 13 Postscript figures, experimental data includes as LATEX comment

Security Against Collective Attacks of a Modified BB84 QKD Protocol with Information only in One Basis

The Quantum Key Distribution (QKD) protocol BB84 has been proven secure against several important types of attacks: the collective attacks and the joint attacks. Here we analyze the security of a modified BB84 protocol, for which information is sent only in the z basis while testing is done in both the z and the x bases, against collective attacks. The proof follows the framework of a previous paper (Boyer, Gelles, and Mor, 2009), but it avoids the classical information-theoretical analysis that caused problems with composability. We show that this modified BB84 protocol is as secure against collective attacks as the original BB84 protocol, and that it requires more bits for testing.Comment: 6 pages; 1 figur