Nonlinear steering control under input magnitude and rate constraints with exponential convergence

A ship steering control is designed for a nonlinear maneuvering model whose rudder manipulation is constrained in both magnitude and rate. In our method, the tracking problem of the target heading angle with input constraints is converted into the tracking problem for a strict-feedback system without any input constraints. To derive this system, hyperbolic tangent ($\tanh$) function and auxiliary variables are introduced to deal with the input constraints. Furthermore, using the feature of the derivative of $\tanh$ function, auxiliary systems are successfully derived in the strict-feedback form. The backstepping method is utilized to construct the feedback control law for the resulting cascade system. The proposed steering control is verified in numerical experiments, and the result shows that the tracking of the target heading angle is successful using the proposed control law.Comment: 12 pages, 6 figures, a preprint submitted to the Journal of Marine Science and Technolog

Flaws in a Verifiably Multiplicative Secret Sharing Scheme from ICITS 2017

In this paper, we point out flaws in an existing verifiably multiplicative secret sharing (VMSS) scheme. Namely, we show that a scheme proposed by Yoshida and Obana presented at ICITS 2017 is insecure against an adversary who corrupts a single player. We then show that in the model of ICITS 2017 which restricts the decoder additive, the error-free verification is impossible. We further show that by allowing a general class of decoders which include a linear one, the scheme is error-free

Recent range expansion and population genetics of the Argentine ant

Dissertação de Mestrado Integrado em Arquitectura, apresentada ao Departamento de Arquitectura da Faculdade de Ciências e Tecnologia da Universidade de Coimbra.A habitação remonta às origens do homem, tendo evoluído do abrigo, que proporcionava proteção, até às casas dos nossos dias, representativas dos indivíduos que as habitam. Na atualidade, no mundo ocidental, a habitação tem que permitir aos seus moradores satisfazer as necessidades básicas de conforto, privacidade, higiene e alimentação, possibilitando um espaço de dormir, de lazer e de trabalho, adaptado às famílias contemporâneas. Numa altura em que é reconhecida a qualidade dos arquitetos portugueses a nível internacional, torna-se pertinente observar/perceber, de que forma estes desenvolvem a habitação unifamiliar, representativa do maior encargo financeiro na vida quotidiana das famílias portuguesas, que conta com o maior número de amadores. De forma a aprofundar a habitação unifamiliar contemporânea, em Portugal, a presente dissertação recorre à análise de dois empreendimentos que lhe servem de casos de estudo, o Bom Sucesso, Architecture Resort, Leisure & Golf, em Óbidos e o Vila Utopia, em Oeiras. Destinados um a primeira habitação e outro a segunda, abrangem um grupo de arquitetos de renome. Para facilitar a sua análise, ambos são estudados quer enquanto conjunto, quer através de algumas moradias representativas dos mesmos.The housing goês back to the origins of man, having evolved from the shelter, which provided protection to the homes of today, representative of the individuals who inhabit them. Today, in the western world, housing is required to allow its residents meet the basic needs of comfort, privacy, hygiene and nutrition, providing a space to sleep, leisure and work, adapted to contemporary families. At a time of recognition of the quality of Portuguese architects internationally, it is pertinent to note/notice, how they develop the single-family housing, representing the largest financial burden on thedaily lives of Portuguese families, which hás the largest number amateur. In order to deepen the contemporary family house in Portugal, this thesis refers to the analysis of two projects which serve as a case study, the Bom Sucesso Architecture Resort, Leisure & Golf in Obidos and the Vila Utopia, in Oeiras. The first one for as the primary housing and the second as a secondary house, cover a group of renowned architects. To facilitate the analysis, both are studied either as a body or through some representative of themselves

Extremely Stochastic Connectivity of Island Mangroves

Studies of mangrove population connectivity have focused primarily on global to regional scales and have suggested potential for long-distance connectivity, with archipelagos serving as stepping stones for trans-oceanic dispersal. However, the contribution of propagule dispersal to connectivity is still largely unknown, especially at local-scale. Identifying fine-scale propagule dispersal patterns unique to individual island systems is important to understand their contribution to global species distributions, and to select appropriate sizes and locations for mangrove conservation in archipelagos. Using population genetic methods and a release-recapture method employing GPS drifting buoys, we investigated the spatiotemporal scale of propagule dispersal of Rhizophora stylosa, one of the widely distributed mangrove species in the Indo-West Pacific. This study sought to quantify intra- and inter-island connectivity and to assess their contributions to oceanic scale dispersal of R. stylosa from the Ryukyu Archipelago, which spans over 545 km in southwestern Japan. Using 7 microsatellite markers, we tested 354 samples collected from 16 fringing populations on 4 islands. We identified 3 genetic populations, indicating distinct genetic structures comprising 3 distinguishable bioregions (genetic clusters). The western end of the archipelago receives relatively frequent migration (m > 0.1), but is genetically isolated from other sites. Based on genetic migration rates, we found that the central area of the archipelago serves as a stepping stone for southwestward, but not northeastward dispersal. On the other hand, with in-situ drifting buoys, we did not confirm prevailing dispersal directionality within the archipelago, instead confirming local eddies. Some buoys trapped in those eddies demonstrated potential for successful beaching from another island. A large portion of buoys were carried predominantly northeastward by the Kuroshio Current and drifted away from the coastal areas into the Pacific, contrary to local migrations. We found that the spatiotemporal scale of propagule dispersal is limited by the distance between islands (< 200km), propagule viability duration, and fecundity. Over all, recruitment does not occur frequently enough to unify the genetic structure in the archipelago, and the Ryukyu Archipelago is isolated in the center of the global mangrove distribution

The evolutionally-conserved function of group B1 Sox family members confers the unique role of Sox2 in mouse ES cells.

BACKGROUND: In mouse ES cells, the function of Sox2 is essential for the maintenance of pluripotency. Since the Sox-family of transcription factors are well conserved in the animal kingdom, addressing the evolutionary origin of Sox2 function in pluripotent stem cells is intriguing from the perspective of understanding the origin of pluripotency. RESULTS: Here we approach this question using a functional complementation assay in inducible Sox2-null ES cells. Assaying mouse Sox proteins from different Groups, we found that only Group B1 and Group G proteins were able to support pluripotency. Interestingly, invertebrate homologs of mammalian Group B1 Sox proteins were able to replace the pluripotency-associated function of mouse Sox2. Moreover, the mouse ES cells rescued by the Drosophila SoxNeuro protein are able to contribute to chimeric embryos. CONCLUSIONS: These data indicate that the function of mouse Sox2 supporting pluripotency is based on an evolutionally conserved activity of the Group B1 Sox family. Since pluripotent stem cell population in developmental process could be regarded as the evolutional novelty in vertebrates, it could be regarded as a co-optional use of their evolutionally conserved function

Superconductor derived from a topological insulator heterostructure

Topological superconductors (TSCs) are of significant current interest because they offer promising platforms for finding Majorana fermions. Here we report on a superconductor synthesized by intercalating Cu into a naturally formed topological insulator (TI) heterostructure consisting of Bi₂Se₃ TI units separated by nontopological PbSe units. Interestingly, in this TI-based superconductor, the specific-heat behavior suggests the occurrence of unconventional superconductivity with gap nodes. The existence of gap nodes in a strongly spin-orbit coupled superconductor would give rise to spin-split Andreev bound states that are the hallmark of topological superconductivity. Hence, this superconductor emerges as an intriguing candidate TSC