Suitable Initial Conditions for Newtonian Simulations with Massive Neutrinos

Initial conditions for cosmological N-body simulations are usually calculated by rescaling the present day linear power spectrum obtained from an Einstein-Boltzmann solver to the initial time employing the scale-independent matter growth function. For the baseline Lambda-CDM model, this has been shown to be consistent with General Relativity (GR) even in the presence of relativistic species such as photons. We show that this approach is not feasible in cosmologies with massive neutrinos and present an alternative method employing the Newtonian motion gauge framework.Comment: 10 pages, 4 figure

Trading off impact and mutation of knowledge by cooperatively learning robots

We present a socially inspired approach that allows agents in Multi-Agent Systems to speed up their own learning process through communication. Thereby, they are able to trade off impact of knowledge by mutation dependent on the recent performance of the interacting agents. This is inspired by social interaction of humans, where the opinions of experts have greater impact on the overall opinion and are incorporated more exactly than those of newbies. The approach is successfully evaluated in a simulation in which mobile robots have to accomplish a task while taking care of timely recharging their resources1st IFIP International Conference on Biologically Inspired Cooperative Computing - Robotics and Sensor NetworksRed de Universidades con Carreras en Informática (RedUNCI

Nonequilibrium nuclear spin states in singly charged semiconductor quantum dots

The spin of a localized charge carrier in a semiconductor nanostructure can be coherently controlled by external electromagnetic fields. At cryogenic temperatures, the spin coherence time is limited by the hyperfine interaction with surrounding nuclear spins. The generation of tailored nuclear spin states, however, may drastically increase the electron spin coherence in comparison to the disordered nuclear spin system. By means of a fully quantum mechanical description, we investigate two particular nonequilibrium situations in which a highly ordered nuclear spin state is achieved. First, we focus on the formation of the nuclear-spin polaron state under optical cooling of the nuclear spins. Kinetic rate equations are developed that account for different effective spin temperatures of the charge carrier and the nuclei and provide analytical access to the crossover temperature of the polaron formation. The rate equations are generalized to a Lindblad formalism enabling the numerical investigation of a cooled system with arbitrary anisotropic hyperfine interaction. The second nonequilibrium situation addressed in this thesis is the periodic optical excitation of singly charged quantum dots subject to a transversal magnetic field. Nuclei-induced frequency focusing of the electron spin precession leads to mode-locked spin dynamics. A revival of the electron spin polarization directly before each pump pulse reflects this synchronization of the spin dynamics to the pumping periodicity. In experiments, a magnetic field dependence of the emerging revival amplitude is observed. Our quantum mechanical approach allows for attributing this dependence to the nuclear Zeeman term. Moreover, we discuss various additional influences on the mode-locking effect. We examine the effect of static nuclear-electric quadrupolar interactions, the characteristics of the laser pulses, and the choice of the pulse train

Trading off impact and mutation of knowledge by cooperatively learning robots

We present a socially inspired approach that allows agents in Multi-Agent Systems to speed up their own learning process through communication. Thereby, they are able to trade off impact of knowledge by mutation dependent on the recent performance of the interacting agents. This is inspired by social interaction of humans, where the opinions of experts have greater impact on the overall opinion and are incorporated more exactly than those of newbies. The approach is successfully evaluated in a simulation in which mobile robots have to accomplish a task while taking care of timely recharging their resources1st IFIP International Conference on Biologically Inspired Cooperative Computing - Robotics and Sensor NetworksRed de Universidades con Carreras en Informática (RedUNCI

Prosody based emotion recognition for MEXI

Abstract — This paper describes the emotion recognition from natural speech as realized for the robot head MEXI. We use a fuzzy logic approach for analysis of prosody in natural speech. Since MEXI often communicates with well known persons but also with unknown humans, for instance at exhibitions, we realized a speaker dependent mode as well as a speaker independent mode in our prosody based emotion recognition. A key point of our approach is that it automatically selects the most significant features from a set of twenty analyzed features based on a training database of speech samples. This is important according to our results, since the set of significant features differs considerably between the distinguished emotions. With our approach we reach average recognition rates of 84 % in speaker dependent mode and 60 % in speaker independent mode. Index Terms — Emotion recognition, prosody, fuzzy rules, robot hea

Learning-based Position and Stiffness Feedforward Control of Antagonistic Soft Pneumatic Actuators using Gaussian Processes

Variable stiffness actuator (VSA) designs are manifold. Conventional model-based control of these nonlinear systems is associated with high effort and design-dependent assumptions. In contrast, machine learning offers a promising alternative as models are trained on real measured data and nonlinearities are inherently taken into account. Our work presents a universal, learning-based approach for position and stiffness control of soft actuators. After introducing a soft pneumatic VSA, the model is learned with input-output data. For this purpose, a test bench was set up which enables automated measurement of the variable joint stiffness. During control, Gaussian processes are used to predict pressures for achieving desired position and stiffness. The feedforward error is on average 11.5% of the total pressure range and is compensated by feedback control. Experiments with the soft actuator show that the learning-based approach allows continuous adjustment of position and stiffness without model knowledge.© 2023 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works

Improved Calibration Procedure for Wireless Inertial Measurement Units without Precision Equipment

Inertial measurement units (IMUs) are used in medical applications for many different purposes. However, an IMU's measurement accuracy can degrade over time, entailing re-calibration. In their 2014 paper, Tedaldi et al. presented an IMU calibration method that does not require external precision equipment or complex procedures. This allows end-users or personnel without expert knowledge of inertial measurement to re-calibrate the sensors by placing them in several suitable but not precisely defined orientations. In this work, we present several improvements to Tedaldi's method, both on the algorithmic level and the calibration procedure: adaptions for low noise accelerometers, a calibration helper object, and packet loss compensation for wireless calibration. We applied the modified calibration procedure to our custom-built IMU platform and verified the consistency of results across multiple calibration runs. In order to minimize the time needed for re-calibration, we analyzed how the calibration result accuracy degrades when fewer calibration orientations are used. We found that N=12 different orientations are sufficient to achieve a very good calibration, and more orientations yielded only marginal improvements. This is a significant improvement compared to the 37 to 50 orientations recommended by Tedaldi. Thus, we were reduced the time required to calibrate a single IMU from ca. 5 minutes to less than 2 minutes without sacrificing any meaningful calibration accuracy

A importância da segurança de dados e informação na função do secretário executivo: breve balanço

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Comunicação e Expressão. Secretariado ExecutivoA profissão de secretário é extremamente antiga e é categorizada por grandes e complexas alterações que acompanharam o mercado corporativo e a sociedade. Porém a sua essência se manteve a mesma ao longo dos anos: a função desse profissional como auxiliar da empresa em sua organização, inicialmente. Isso é, organizar compromissos e reuniões, gerenciar tarefas, definir o tempo necessário e o momento em que cada atividade ou evento irá ocorrer, fazer contatos, gerenciar fornecedores, marcar e desmarcar compromissos, acompanhar o desenrolar das ações burocráticas entre outros. Entretanto, uma das mais impactantes mudanças na profissão e no mercado corporativo foi motivada pela pandemia do COVID-19, exigindo que boa parte das organizações partissem para o modelo de home office e exigindo que o profissional se reinventasse para lidar com tais alterações e seguir cumprindo com suas tarefas, agora de forma remota. Tal realidade intensificou ainda mais o processo que já estava ocorrendo em quase todos os setores do mundo: a migração de serviços físicos para o meio digital. Obviamente, existem muitas vantagens nesse processo, mas perigos, também. A segurança dos dados e das informações é fundamental para a condução de um bom trabalho no campo do secretariado executivo, e estabelecer a importância dessa segurança na função do secretário é o objetivo de pesquisa do presente trabalho. A metodologia de pesquisa é bibliográfica e descritiva.The profession secretariat is extremely old and is categorized by large and complex changes that have accompanied the corporate market and society. However, its essence has remained the same over the years: it is the function of this professional to assist the company in its organization, primarily. That is, organizing appointments and meetings, managing tasks, defining the time needed and the moment when everything will occur, making contacts, managing suppliers, making and unmarking appointments, following the course of bureaucratic actions and others. However, one of the most impactful changes in the profession and in the corporate market was motivated by the pandemic of COVID-19, requiring that a large number of organizations move to a home office and demanding that the secretariat reinvent itself to deal with such changes and continue to comply with the your tasks, now remotely. This reality further intensifies a process that was already taking place in almost all sectors of the world: the migration of services to the digital environment. Obviously, there are many advantages to this process, but dangers as well. The security of data and information is fundamental for conducting a good job in the executive secretariat and establishing the importance of this security in the role of the secretary is the research objective of the present work. The research methodology is descriptive and bibliographic search