Contextual novelty changes reward representations in the striatum

Reward representation in ventral striatum is boosted by perceptual novelty, although the mechanism of this effect remains elusive. Animal studies indicate a functional loop (Lisman and Grace, 2005) that includes hippocampus, ventral striatum, and midbrain as being important in regulating salience attribution within the context of novel stimuli. According to this model, reward responses in ventral striatum or midbrain should be enhanced in the context of novelty even if reward and novelty constitute unrelated, independent events. Using fMRI, we show that trials with reward-predictive cues and subsequent outcomes elicit higher responses in the striatum if preceded by an unrelated novel picture, indicating that reward representation is enhanced in the context of novelty. Notably, this effect was observed solely when reward occurrence, and hence reward-related salience, was low. These findings support a view that contextual novelty enhances neural responses underlying reward representation in the striatum and concur with the effects of novelty processing as predicted by the model of Lisman and Grace (2005)

Order-of-magnitude speedup for steady states and traveling waves via Stokes preconditioning in Channelflow and Openpipeflow

Steady states and traveling waves play a fundamental role in understanding hydrodynamic problems. Even when unstable, these states provide the bifurcation-theoretic explanation for the origin of the observed states. In turbulent wall-bounded shear flows, these states have been hypothesized to be saddle points organizing the trajectories within a chaotic attractor. These states must be computed with Newton's method or one of its generalizations, since time-integration cannot converge to unstable equilibria. The bottleneck is the solution of linear systems involving the Jacobian of the Navier-Stokes or Boussinesq equations. Originally such computations were carried out by constructing and directly inverting the Jacobian, but this is unfeasible for the matrices arising from three-dimensional hydrodynamic configurations in large domains. A popular method is to seek states that are invariant under numerical time integration. Surprisingly, equilibria may also be found by seeking flows that are invariant under a single very large Backwards-Euler Forwards-Euler timestep. We show that this method, called Stokes preconditioning, is 10 to 50 times faster at computing steady states in plane Couette flow and traveling waves in pipe flow. Moreover, it can be carried out using Channelflow (by Gibson) and Openpipeflow (by Willis) without any changes to these popular spectral codes. We explain the convergence rate as a function of the integration period and Reynolds number by computing the full spectra of the operators corresponding to the Jacobians of both methods.Comment: in Computational Modelling of Bifurcations and Instabilities in Fluid Dynamics, ed. Alexander Gelfgat (Springer, 2018

Onboard processor technology review

The general need and requirements for the onboard embedded processors necessary to control and manipulate data in spacecraft systems are discussed. The current known requirements are reviewed from a user perspective, based on current practices in the spacecraft development process. The current capabilities of available processor technologies are then discussed, and these are projected to the generation of spacecraft computers currently under identified, funded development. An appraisal is provided for the current national developmental effort

Physical properties of alternatives to the fully halogenated chlorofluorocarbons

Presented here are recommended values and correlations of selected physical properties of several alternatives to the fully halogenated chlorocarbons. The quality of the data used in this compilation varies widely, ranging from well-documented, high accuracy measurements from published sources to completely undocumented values listed on anonymous data sheets. That some of the properties for some fluids are available only from the latter type of source is clearly not the desired state of affairs. While some would reject all such data, the compilation given here is presented in the spirit of laying out the present state of knowledge and making available a set of data in a timely manner, even though its quality is sometimes uncertain. The correlations presented here are certain to change quickly as additional information becomes available

Reducing torque pulsations in PMa-SynRM: A way for improving motor performance

This paper aims to evaluate the performance of synchronous reluctance motors assisted by a permanent magnet (PMa-SynRM) focused on efficiency and torque pulsations. PMa-SynRM shows high efficiency and power factor, compared to induction motors (IM), although they have a greater cost. These machines develop relatively high torque ripple, cogging torque, and torque imbalances. Consequently, the electromagnetic torque is reduced, the motor temperature is increased, and mechanical vibrations are induced. The optimal design of the machine structures such as flow barriers, permanent magnets, and stator slots, among others, allow reducing torque pulsations. A comparison is made between different designs of the PMa-SynRM reported in the scientific literature, and the effects on efficiency, torque pulsation, and operating costs are evaluated. A case study on the motor driving the air conditioner blower in a hotel room was made, to determine the best economic variant between IM or PMa-SynRM. A sensitive analysis was made to evaluate several uncertainties. The advantages of using one of the PMa-SynRM analyzed were demonstrated. Also, it was proved that the investment is feasible economically, although NPV and payback are not the best, due to low load factor in inverter-controlled motors in air conditioners

Універсальна модель гібридного тягово-транспортного засобу (ТТЗ) сільськогосподарського призначення

У роботі розглянуто можливість дослідження електромагнітних процесів, що відбуваються у електромеханічній трансмісії під час обробки ґрунту за допомогою універсальної моделі руху машинно-тракторного агрегату. Було промодельовано різні типи тягових електричних машин та проведено порівняльний аналіз діапазону коливання обертів двигуна внутрішнього згоряння (ДВЗ), його потужності та питомого споживання палива електротрансмісії відносно механічної передачі. На базі універсальної моделі електротрансмісії побудовано модель машинно-тракторного агрегату з комбінованим джерелом енергоживлення та показано позитивний ефект від використання накопичувача енергії (акумуляторної батареї). Проведено порівняння результатів моделювання з експериментальними даними і підтверджено адекватність результатів моделювання.В работе рассмотрены возможности исследования электромагнитных процессов, которые протекают в электромеханической трансмиссии во время обработки почвы, при помощи универсальной модели движения машино-тракторного агрегата. Были промоделированы различные типы тяговых электрических машин и проведен сравнительный анализ диапазона колебаний оборотов ДВС, его мощности и удельного потребления топлива электротрансмиссии относительно механической передачи. На базе универсальной модели электротрансмиссии построена модель машино-тракторного агрегата с комбинированным источником энергопитания и показан положительный эффект от использования накопителя энергии (аккумуляторной батареи). Проведено сравнение результатов моделирования с экспериментальными данными и подтверждена адекватность результатов моделирования.The paper discusses the possibility of investigating electromagnetic processes in elektromehanity transmission during tillage using a universal model of the machine-tractor unit. Were modeled different types of traction electric cars and a comparative analysis of a range of co-fluctuation momentum ICE, its power and specific fuel consumption elektrotransmisiyi relatively mechanical-term transfer. On the basis of universal model elektrotransmisiyi built model cars and tractor aggregation that with the combined power supply and the positive effect of using charger energy (battery). A comparison of simulation results with experimental data and confirmed the adequacy of the modeling results