Mamoru Kawaguchi: Master of motion and lightness of structures

[EN] Mamoru Kawaguchi (1932-2019) was one of the great structural engineers of the late 20th century. He developed his career mostly in Japan and he has also superb works in China, Singapore and Spain. The spectrum of his structures is manifold: he designed shells, space frames, inflatable structures, tension structures, timber¿steel hybrid systems and so on. With them, he conceived and provided the bones and muscles of sports halls, exhibition halls, museums, railway stations, towers, bridges and sculptures. Kawaguchi collaborated with some of the best architects of his time: Kenzo Tange, Arata Isozaki and Kazuyo Sejima just to cite some of the internationally most renowned. For his works, he was awarded many times in Japan, as well as internationally (the Architectural Institute of Japan award, the International Association for Shell and Spatial Structures Torroja Medal, the International Association for Bridge and Structural Engineering International Award and many others). In this article, I review Mamoru Kawaguchi¿s main professional and academic achievements, and discuss his design philosophy, sources of inspiration and means to develop his ideas from my own personal experience.Lazaro, C. (2020). Mamoru Kawaguchi: Master of motion and lightness of structures. International Journal of Space Structures. 35(1-2):35-42. https://doi.org/10.1177/0956059920931316S3542351-2Kawaguchi, M. (2006). Yoshikatsu Tsuboi, Distinguished Researcher, Warmhearted Teacher and Talented Structural Designer. International Journal of Space Structures, 21(1), 31-41. doi:10.1260/026635106777641126Lázaro, C., & Domingo, A. (2010). Detailing and Construction of the Pantadome Roof Structure for a Bullring in Xàtiva (Spain). International Journal of Space Structures, 25(4), 229-241. doi:10.1260/0266-3511.25.4.22

Robustness of cultural communities in an open-ended Axelrod's model

We consider an open-ended set of cultural features in the Axelrod's model of cultural dissemination. By replacing the features in which a high degree of consensus is achieved by new ones, we address here an essential ingredient of societies: the evolution of topics as a result of social dynamics and debate. Our results show that, once cultural clusters have been formed, the introduction of new topics into the social debate has little effect on them, but it does have a significant influence on the cultural overlap. Along with the Monte-Carlo simulations, we derive and numerically solve an equation for the stationary cultural overlap based on a mean-field approach. Although the mean-field analysis reproduces qualitatively the characteristic phase transition of the Axelrod's model, it underestimates the cultural overlap, highlighting the role of the local interactions in the Axelrod's dynamics, as well as the correlations between the different cultural features.Comment: 6 pages and 5 figure

A networked voting rule for democratic representation

We introduce a general framework for exploring the problem of selecting a committee of representatives with the aim of studying a networked voting rule based on a decentralized large-scale platform, which can assure a strong accountability of the elected. The results of our simulations suggest that this algorithm-based approach is able to obtain a high representativeness for relatively small committees, performing even better than a classical voting rule based on a closed list of candidates. We show that a general relation between committee size and representatives exists in the form of an inverse square root law and that the normalized committee size approximately scales with the inverse of the community size, allowing the scalability to very large populations. These findings are not strongly influenced by the different networks used to describe the individuals interactions, except for the presence of few individuals with very high connectivity which can have a marginally negative effect in the committee selection process.Comment: Submitted for publicatio

Analysis of a networked social algorithm for collective selection of a committee of representatives

A recent work by Hern\'andez et al. introduced a networked voting rule supported by a trust-based social network, where indications of possible representatives were based on individuals opinions. Individual contributions went beyond a simple vote-counting and were based on proxy voting. These mechanisms generated a high level of representativeness of the selected committee, weakening the possibility of relations of patronage. By incorporating the integrity of individuals and its perception, here we address the question of the trustability of the resulting committee. Our results show that this voting rule provides high representativeness for small committees with a high level of integrity. Furthermore, the voting system displays robustness to a strategic and untruthful application of the voting algorithm.Comment: 7 pages and 8 figures. Submitted for publication. arXiv admin note: text overlap with arXiv:1801.0539

Classical Models of the Spin 1/2 System

We proposed a Quaternionic mechanical system motivated by the Foucault pendulum as a classical model for the dynamics of the spin 1/2 system. We showed that this mechanical system contains the dynamics of the spin state of the electron under a uniform magnetic field as it is given by the Schrodinger-Pauli-Equation (SPE). We closed with a characterization of the dynamics of this generalized classical system by showing that it is equivalent with the dynamics of the Schrodinger Pauli Equation as long as the solutions to the generalized classical system are roots of the Lagrangian, that is the condition L = 0 holds

Performance Evaluation of Underwater (UW) Welding System with Friction Stir Welding (FSW) Method on 316L Stainless Steel Exposed to Sea Water

Friction Stir Welding (FSW) is a solid-state welding technique that can produce high-quality joints without defects that commonly occur in liquid welding. However, FSW has limitations in underwater applications due to the friction between the tool and the material that causes a decrease in heat efficiency and shear force. To overcome this problem, this study proposes an underwater welding (UW) system with the FSW method on 316L stainless steel exposed to seawater. This UW-FSW system uses a high-speed rotating tool surrounded by an inert gas shroud to prevent direct contact between the tool and seawater. The aim of this study is to evaluate the performance of this UW-FSW system in terms of mechanical properties, microstructure, and corrosion resistance of 316L stainless steel joints. The results of this study show that the UW-FSW system can produce joints with better tensile strength, hardness, and corrosion resistance than conventional FSW. This is due to the rapid cooling, reduction of oxidation, and formation of a thicker passive layer on the joint surface. This study provides a contribution to the development of environmentally friendly and efficient underwater welding technology

Kinetics and Mechanism of Gas-Phase Thermolysis Using Headspace-Gas Chromatographic Analysis

Headspace gas chromatography is employed in order to study the thermal decomposition reaction of gaseous di-tert-butyl peroxide (DTBP) in the 130°C to 160°C temperature range and in the presence of n-hexane as the internal standard and nitrogen as the carrier gas. The reaction exclusively yields acetone and ethane as products. First-order kinetics are observed, including when the surface-to-volume ratio (S/V) of the Pyrex 20-mL vial employed as the reactor is increased by packing it with silanized glass wool. However, a small increase in the rate constant values is observed at each temperature, which supports a heterogeneous surface process in DTBP decomposition. The rate constant's dependence on the homogeneous unimolecular decomposition reaction corresponds to the O-O bond rupture of the DTBP molecule in a stepwise three-stage mechanism. Thus, the relevant question of the participation of a surface catalytic effect in the DTBP gas-phase thermolysis can easily be assessed through the procedure described in this work. In general, this is advantageous for the rapid investigation of the reaction kinetics of volatile compounds at different temperatures.Fil: Cafferata, Lazaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas ; ArgentinaFil: Manzione, Carlos Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas ; Argentin

Evolvable circuit with transistor-level reconfigurability

An evolvable circuit includes a plurality of reconfigurable switches, a plurality of transistors within a region of the circuit, the plurality of transistors having terminals, the plurality of transistors being coupled between a power source terminal and a power sink terminal so as to be capable of admitting power between the power source terminal and the power sink terminal, the plurality of transistors being coupled so that every transistor terminal to transistor terminal coupling within the region of the circuit comprises a reconfigurable switch

Evolutionary Technique for Automated Synthesis of Electronic Circuits

An evolvable circuit includes a plurality of reconfigurable switches, a plurality of transistors within a region of the circuit, the plurality of transistors having terminals, the plurality of transistors being coupled between a power source terminal and a power sink terminal so as to be capable of admitting power between the power source terminal and the power sink terminal, the plurality of transistors being coupled so that every transistor to transistor terminal coupling within the region of the circuit comprises a reconfigurable switch