Constraining the evolutionary history of Newton's constant with gravitational wave observations

Space-borne gravitational wave detectors, such as the proposed Laser Interferometer Space Antenna, are expected to observe black hole coalescences to high redshift and with large signal-to-noise ratios, rendering their gravitational waves ideal probes of fundamental physics. The promotion of Newton's constant to a time-function introduces modifications to the binary's binding energy and the gravitational wave luminosity, leading to corrections in the chirping frequency. Such corrections propagate into the response function and, given a gravitational wave observation, they allow for constraints on the first time-derivative of Newton's constant at the time of merger. We find that space-borne detectors could indeed place interesting constraints on this quantity as a function of sky position and redshift, providing a {\emph{constraint map}} over the entire range of redshifts where binary black hole mergers are expected to occur. A LISA observation of an equal-mass inspiral event with total redshifted mass of 10^5 solar masses for three years should be able to measure $\dot{G}/G$ at the time of merger to better than 10^(-11)/yr.Comment: 11 pages, 2 figures, replaced with version accepted for publication in Phys. Rev. D

Investigating the thermal profile of a marine vessel engine room through simulation with field measurements

This paper assesses the use of computational fluid dynamics (CFD) to model the ventilation of a working marine vessel, its performance in extreme climates, and potential improvements to the ventilation system which could lead to increased efficiencies of the engine and generator set.Comparisons between data gathered on the marine vessel and the computational model show good agreement, with an average discrepancy in temperature of 0.4%. The model showed that the current ventilation system was inadequate for the use of the marine vessel in Arctic waters. In contrast, the model showed the vessel was suited for tropical waters, and that the boat complied with British Standards for ventilation.Directing the flow within the engine room was found to improve the overall cooling of the room, and reduce the range of temperatures to improve thermal comfort. Directing the flow has shown reduced intake temperatures of the engine and generator set, improving efficiencies by 0.5% and 0.57% respectively. This paper demonstrates that the use of CFD to model marine vessel engine rooms can be used in retrospective design of ventilation systems, furthermore, it can be a tool utilised in the design stages for optimised engine rooms ventilation systems

Modelos de gerenciamento de enclaves para execução segura de componentes de software

Orientador: Carlos Alberto MazieroTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa : Curitiba, 04/12/2020Inclui referências: p. 106-115Área de concentração: Ciência da ComputaçãoResumo: A confidencialidade dos dados está se mostrando cada vez mais importante para os usuários de computadores, seja em um ambiente corporativo ou até mesmo em um ambiente doméstico. Atualmente, não somente dados sensíveis às empresas estão trafegando pela rede ou sendo manipulados pelos mais diversos programas de computador, mas também tem-se um intenso uso de aplicações para transações bancárias e outras aplicações de uso corriqueiro que manipulam dados sensíveis dos usuários, os quais devem ter sua confidencialidade e integridade garantidas. Nesse sentido, tem-se variadas soluções sendo propostas para manter a confidencialidade e integridade dos dados, dentre elas a arquitetura Intel SGX (Software Guard Extensions), a qual possui mecanismos para que as aplicações e os dados sejam encapsulados em uma área protegida da memória com acesso restrito, impossibilitando o acesso nessa região de memória a outras aplicações ou ao próprio sistema operacional. A utilização de tais mecanismos para prover a confidencialidade e integridade dos dados sensíveis da aplicação acarreta em um impacto de desempenho durante a sua execução, devido às restrições e verificações impostas pela arquitetura Intel SGX. O presente trabalho busca analisar os modelos de programação que são aplicados em soluções que utilizam a arquitetura Intel SGX e apresentar alternativas que buscam um uso mais eficiente dos recursos providos por tal arquitetura e também a redução do impacto de desempenho decorrente de sua utilização. Assim, são apresentados dois modelos de gerenciamento: (i) compartilhamento de enclaves; e (ii) pool de enclaves. Para a aplicação de tais modelos, é proposta uma arquitetura de um provedor de enclaves, que oferece um desacoplamento entre o enclave e a aplicação que o utiliza, permitindo aplicar os modelos de gerenciamento propostos e oferecer os recursos providos pelos enclaves às aplicações na forma de serviços. Um protótipo é construído para avaliar a arquitetura e modelos propostos, com os testes de desempenho demonstrando consideráveis reduções no impacto para requisição de enclaves, enquanto garante boa resposta para atender múltiplas requisições simultâneas. Assim, conclui-se que a utilização de modelos arquiteturais de software podem trazer benefícios no gerenciamento de recursos e ganho de desempenho na execução de aplicações seguras. Palavras-chave: Intel SGX, modelos de programação, arquitetura de software, padrões de projeto, desempenho, otimização de recursos.Abstract: Data confidentiality is becoming increasingly important to computer users, whether in a corporate environment or even in a home environment. Not only are business-sensitive data currently being trafficked across the network or being handled by a variety of software, but there is also an intense use of applications for banking transactions and other commonly used applications that manipulate sensitive user data, which must have their confidentiality and integrity guaranteed. In this sense, there are several solutions being proposed to maintain the confidentiality and integrity of the data, among them the Intel SGX (Software Guard Extensions) architecture, which has mechanisms to encapsulate applications and data in a protected area of memory having restricted access, making it impossible to access this region of memory to other applications or to the operating system. The use of such mechanisms to provide the confidentiality and integrity of sensitive data results in a performance impact during the application execution, due to the restrictions and verifications imposed by the Intel SGX architecture. The present work aims to analyze the programming models that are applied in solutions that use the Intel SGX architecture and present alternatives that seek a more efficient use of the resources provided by this architecture and also the reduction of the performance impact due to its use. Thus, two management models are presented: (i) enclave sharing; and (ii) enclave pool. In order to apply such models, an architecture of an enclave provider is proposed, which offers a decoupling between the enclave and the application that uses it, allowing to apply the proposed management models and offering the resources provided by the enclaves to the applications in "as a service" format. A prototype is built to evaluate the proposed architecture and models, with the performance tests demonstrating considerable reductions in the impact for enclave requests, while guaranteeing good response to attend simultaneous requests. Thus, it is concluded that the use of architectural software models can bring benefits in resource management and performance gains in the execution of secure applications. Keywords: Intel SGX, programming models, software architecture, design patterns, performance, resource optimization

Sistema para análise de qualidade de energia baseado em software livre

This document describes the development and implementation of a power analyzer system that is composed by a signal acquisition hardware and a power analyzer software. The acquisition system contains an interface to connect personal computers and transfer the acquired data to be analized by the software. The software was developed using free tools and frameworks, what reduces the development cost. Furthermore, the latest de nitions for power computation are used, that are described by IEEE Std 1459-2010, for unbalanced and non-sinusoidal systems. ITo obtain results with better accuracy, it is used the Kalman lter to decompose the voltage and current signals into their fundamental and harmonic components. This document describe the development of hardware and software, including the internal software structure and implementation details of the power computations. Finally, simulation and experimental results are presented to validate the proposal. Then, these results are compared with theoretical results and the values obtained by the Fluke 434 Power Analyzer.CAPESEste trabalho apresenta o desenvolvimento e implementação de um sistema constitu ído por um hardware para aquisição de sinais e um software para a análise da qualidade de energia. O sistema de aquisição contém uma interface para conexão com computadores pessoais para o envio dos dados coletados para serem analisados via software. O software é desenvolvido utilizando-se ferramentas livres, reduzindo, assim, o custo de implementação do sistema. Além disso, são empregadas as mais recentes de nições para o cálculo de potências, presentes na Norma IEEE 1459-2010, a qual descreve os cálculos de potências para sistemas desbalanceados em regimes não senoidais. Para se obter uma maior precisão nos resultados, é utilizado o ltro de Kalman para a decomposição dos sinais de tensão e corrente em suas componentes fundamental e harmônicas, o qual apresenta melhores resultados em regimes transitórios quando comparados à FFT. O trabalho descreve todo o desenvolvimento de hardware e software, incluindo a estrutura interna do software e detalhes da implementação computacional dos cálculos. Por fim, são apresentados os resultados simulados e experimentais para a validação da proposta, os quais são comparados com resultados teóricos e os resultados obtidos pelo analisador de energia Fluke 434

Secure Cloud Storage with Client-Side Encryption Using a Trusted Execution Environment

With the evolution of computer systems, the amount of sensitive data to be stored as well as the number of threats on these data grow up, making the data confidentiality increasingly important to computer users. Currently, with devices always connected to the Internet, the use of cloud data storage services has become practical and common, allowing quick access to such data wherever the user is. Such practicality brings with it a concern, precisely the confidentiality of the data which is delivered to third parties for storage. In the home environment, disk encryption tools have gained special attention from users, being used on personal computers and also having native options in some smartphone operating systems. The present work uses the data sealing, feature provided by the Intel Software Guard Extensions (Intel SGX) technology, for file encryption. A virtual file system is created in which applications can store their data, keeping the security guarantees provided by the Intel SGX technology, before send the data to a storage provider. This way, even if the storage provider is compromised, the data are safe. To validate the proposal, the Cryptomator software, which is a free client-side encryption tool for cloud files, was integrated with an Intel SGX application (enclave) for data sealing. The results demonstrate that the solution is feasible, in terms of performance and security, and can be expanded and refined for practical use and integration with cloud synchronization services

Lorentz-covariant quantum mechanics and preferred frame

In this paper the relativistic quantum mechanics is considered in the framework of the nonstandard synchronization scheme for clocks. Such a synchronization preserves Poincar{\'e} covariance but (at least formally) distinguishes an inertial frame. This enables to avoid the problem of a noncausal transmision of information related to breaking of the Bell's inequalities in QM. Our analysis has been focused mainly on the problem of existence of a proper position operator for massive particles. We have proved that in our framework such an operator exists for particles with arbitrary spin. It fulfills all the requirements: it is Hermitean and covariant, it has commuting components and moreover its eigenvectors (localised states) are also covariant. We have found the explicit form of the position operator and have demonstrated that in the preferred frame our operator coincides with the Newton--Wigner one. We have also defined a covariant spin operator and have constructed an invariant spin square operator. Moreover, full algebra of observables consisting of position operators, fourmomentum operators and spin operators is manifestly Poincar\'e covariant in this framework. Our results support expectations of other authors (Bell, Eberhard) that a consistent formulation of quantum mechanics demands existence of a preferred frame.Comment: 21 pages, LaTeX file, no figure

Quantifying full phenological event distributions reveals simultaneous advances, temporal stability and delays in spring and autumn migration timing in long-distance migratory birds

Acknowledgements We thank all Fair Isle Bird Observatory staff and volunteers for help with data collection and acknowledge the foresight of George Waterston and Ken Williamson in instigating the observatory and census methodology. We thank all current and previous directors of Fair Isle Bird Observatory Trust for their contributions, particularly Dave Okill and Mike Wood for their stalwart support for the long-term data collection and for the current analyses. Dawn Balmer and Ian Newton provided helpful guidance on manuscript drafts. We thank Ally Phillimore and two anonymous referees for helpful comments. This study would have been impossible without the Fair Isle community's invaluable support and patience over many decades, which is very gratefully acknowledged. WTSM and JMR designed and undertook analyses, wrote the paper and contributed to data collection and compilation, MB contributed to analysis and editing, all other authors oversaw and undertook data collection and compilation and contributed to editing.Peer reviewedPostprin