Towards federated learning over large-scale streaming data

2020 Spring.Includes bibliographical references.Distributed Stream Processing Engines (DSPEs) have seen significant deployment growth along with an increase in streaming data sources such as sensor networks. These DSPEs enable processing large amounts of streaming data in a cluster of commodity machines to extract knowledge and insights in real-time. Due to fluctuating data arrival rates in real-world applications, modern DSPEs often provide auto-scaling. However, the existing designs of advanced analytical frameworks are not effectively aligned with scalable streaming computing environments. We have designed and developed ORCA, a federated learning architecture that supports the training of traditional Artificial Neural Networks as well as Convolutional Neural Networks and Long Short-term Memory Network based models while ensuring resiliency during scaling. ORCA also introduces dynamic adjustment of the 'elasticity' hyper-parameter for rescaled computing environments. We estimate this elasticity hyper-parameter using reinforcement learning. Our empirical benchmarks show that ORCA is capable of achieving an MSE of 0.038 over real-world streaming datasets

Investigation of Direct Injection Fuel Sprays in High Velocity Air Flows

The study of single-plume sprays into cross-flowing air is found extensively in literature, however, with the continued development of the Spark Ignition Direct Injection (SIDI) engine, the behaviour of multi-plume sprays in cross-flowing conditions is of interest. In the present work, the injection of a multi-plume spray into a high-velocity cross-flow is investigated; an experimental apparatus capable of providing a cross-flow with core velocities higher than 200 m/s is developed; analysis techniques are developed to characterize the cross-flow and multi-plume spray independently; the multi-plume spray is characterized as it issues into the cross-flowing air. The round air jet used for the cross-flow was designed using the concepts put forth for the design of wind tunnel contractions. The axial and radial velocities were measured using a Particle Image Velocimetry system from LaVision Inc. and the potential core length determined for the core velocities corresponding to Mach numbers of 0.35 and 0.58. It was determined that the potential core length increases with increasing Mach number and that increased compressibility, leads to reduced mixing within the core. Furthermore, velocity profiles of the air jet show that self-similarity is preserved within the shear layer of the initial region. The multi-plume spray was also characterized in quiescent conditions for 10 and 15 MPa injection pressures. It was found that the penetration depth and spray width increased with increasing injection pressure, but that the spray angle decreased with increasing pressure. The increase in penetration depth is consistent with the findings presented in literature, while the decrease in spray angle with increasing pressure is contrary to literature. Next, the multi-plume spray, injected at 10 and 15 MPa, is characterized as it issues into the cross-flowing air stream at Mach numbers equal to 0.35 and 0.58. The tail length and penetration are measured and it is found that for the first, the cross-flow velocity is the primary factor with higher cross-flow velocity resulting in a longer tail length, while for the latter, the injection pressure is the major factor, with higher injection pressures resulting in higher penetrations. That being said, the injection pressure does play a small role in the tail length, with the 15 MPa injection having a slightly longer tail length than the 10 MPa injection in the Mach number 0.58 cross-flow. This is attributed to the finer atomization, which is expected from the 15 MPa injection and which leads to quicker entrainment of fuel droplets into the cross-flow. The spray axis was predicted for each set of conditions from 0.1 ms to 1.0 ms after Start of Fuel (SOF). It was found that before 0.3 ms, the spray retains its multi-plume nature, while after 0.3 ms it behaves like a single-plume spray. Once the spray has crossed this transition point, the spray axis is temporally independent and can be predicted by the logarithmic models, similar to those used for single-plume sprays in cross-flow. The accuracy of this fit is improved upon, with the presentation of a modified correlation, which includes the momentum flux ratio inside of the logarithmic term. Finally, the multi-plume spray issuing into the cross-flow is characterized using PIV to measure droplet velocities. It is observed that the cross-flow momentum is imparted to the smaller droplets within the 15 MPa spray more easily than to those of the 10 MPa injection, but that the 15 MPa sprays also retain their momentum in the radial direction longer than the 10 MPa sprays. As such, the 10 MPa sprays align with the cross-flow axis faster.1 yea

Causas e consequências da crise econômica brasileira de 2014 a 2016

Orientador : José Wladimir Freitas da FonsecaMonografia (graduação) - Universidade Federal do Paraná, Setor de Ciências Sociais Aplicadas, Curso de Ciências Econômicas.Inclui referênciasResumo : No período de 2002 a 2014 a econômica brasileira obteve um bom desempenho econômico, o qual, pode ser atribuído em grande parte ao boom de commodites e a manutenção das políticas econômicas implementadas pelo governo anterior nos primeiros anos do governo Lula. Apesar disso, os governos Lula e Dilma erraram ao apostar excessivamente nas políticas de desoneração fiscal, subsídios, manutenção dos preços administrados, aumento do crédito via bancos públicos e BNDES, os quais agravaram ainda mais a situação das contas públicas, aumentando a necessidade de financiamento do governo, o qual, não possui a mesma credibilidade, em face das escolhas de políticas econômicas realizadas, em razão disto para se financiar, o mesmo necessita aumentar a taxa de juros, aumentado ainda mais a relação dívida pública/PIB, deste modo, ao inovar nas políticas econômicas o governo colocou o país na pior crise da história da economia brasileira. Contudo, este cenário poderia ser outro, visto que se estes governos promovessem uma política objetivando o crescimento econômico, como relatado em suas campanhas eleitorais

Improving Efficiency of Human-Robot Coexistence While Guaranteeing Safety: Theory and User Study

Guaranteeing safety for humans in shared workspaces is not trivial. Not only must all possible situations be provably safe, but the human must feel safe as well. While robots are gradually leaving their cages, due to strict safety requirements, engineers often only replace physical cages with static safety zones - when the safety zone is entered, the robot is forced to stop. This can lead to excessive robot downtime. We present a concept for guaranteeing non-collision between humans and robots whilst maximising robot uptime and staying on-path. We evaluate how users react to this approach, in a trial over three non-consecutive days, compared to a control approach of static safety zones. We measure working efficiency as well as human factors such as trust, understanding of the robot, and perceived safety. Using our approach, the robot is indeed more efficient compared to static safety zones and the effect persists over multiple trials on separate days. We also observed that understanding of the robot's movement increased for our method over the course of trials, and the perceived safety of the robot increased for both our method and the control

Model Mediated Teleoperation with a Hand-Arm Exoskeleton in Long Time Delays Using Reinforcement Learning

Telerobotic systems must adapt to new environmental conditions and deal with high uncertainty caused by long-time delays. As one of the best alternatives to human-level intelligence, Reinforcement Learning (RL) may offer a solution to cope with these issues. This paper proposes to integrate RL with the Model Mediated Teleoperation (MMT) concept. The teleoperator interacts with a simulated virtual environment, which provides instant feedback. Whereas feedback from the real environment is delayed, feedback from the model is instantaneous, leading to high transparency. The MMT is realized in combination with an intelligent system with two layers. The first layer utilizes Dynamic Movement Primitives (DMP) which accounts for certain changes in the avatar environment. And, the second layer addresses the problems caused by uncertainty in the model using RL methods. Augmented reality was also provided to fuse the avatar device and virtual environment models for the teleoperator. Implemented on DLR's Exodex Adam hand-arm haptic exoskeleton, the results show RL methods are able to find different solutions when changes are applied to the object position after the demonstration. The results also show DMPs to be effective at adapting to new conditions where there is no uncertainty involved

CT characterisation and classification of feline temporomandibular joint trauma : a case series of 79 cats

Research Areas: Veterinary SciencesObjectives The aim of this study was to characterise and describe patterns of temporomandibular joint (TMJ) injuries occurring in cats using CT. Methods A cross-sectional study was carried out in adherence with the STROBE guidelines. Among the medical and CT records of 79 cats, 158 TMJs were reviewed in a collaborative study between six institutions. Results TMJ injuries were most commonly unilateral, representing 70.9% of cases. The mandibular condyle was fractured in 88 cases (55.7%) of the 158 TMJs observed. Of those, 84.0% were intra-articular condyle fractures, with the medial half of the mandibular condyle over-represented. Luxations occurred in 32.9% of cases, which was 19.0% of all evaluated TMJs. Rostrodorsal luxations were most common representing 87.0% of all luxations. Temporal bone fractures were observed in 30.4% of all cases, which was 18.4% of TMJs. The majority of fractures were of an unknown cause. When the cause was determined, road traffic accident (RTA) was the most frequent, followed by animal interaction, other external forces (sharp or blunt force) and high-rise trauma. Bilateral injuries were 13.1 times more likely to occur in high-rise trauma (P=0.01) and temporal bone fracture was significantly associated with RTAs (P=0.016). No other significant associations were observed between cause of injury and the resulting TMJ injury pattern. Conclusions and relevance Various TMJ injury patterns can occur in cats as a result of trauma. Intra-articular fractures of the medial half of the mandibular condyle occur most commonly. Although unilateral injuries are more frequent, high-rise trauma tends to present with bilateral lesions. Further studies with a larger sample size should be performed to better understand TMJ patterns of injury and how they relate to possible causes.info:eu-repo/semantics/publishedVersio

Building on the Moon Using Additive Manufacturing: Discussion of Robotic Approaches

We present two concepts for building structures on the moon. The first involves an all-purpose robot with exchangeable tools, able to excavate regolith, produce slurry and print a structure. The second involves a team of robots: one excavator, one sintering using sunlight, and another gathering the sintered bricks and building a structure. ESA's Space Resources Strategy sets the challenge of achieving human presence at the Moon, sustained by local resources, by 2040, which includes in-situ manufacturing and construction. We take a realistic look at the feasibility of these concepts and their component technologies, and their challenges with respect to the state of the art and expected technological readiness in the next 2-5 years