Duty ratio modulation direct torque control of brushless doubly-fed machines

For the brushless doubly-fed machine (BDFM), traditional direct torque control (DTC) has many problems such as big output torque ripple and uncertain inverter switch frequency. Based on the analysis of traditional DTC, this paper proposed a new torque control which applied duty ratio modulation into direct torque control. This new control method can decrease the torque ripple effectively by adding zero voltage in each control cycle. According to the brushless BDFM state equation and the prediction of torque, flux linkage in the next moment and the theory of electromagnetic torque equals to referenced value at the instant moment in one control cycle, torque ripple can be decreased. Through theoretical analysis and experiments, the proposed control method has all advantages of traditional direct torque control and can decrease torque ripple and flux linkage ripple, which can optimize the performance of direct torque control

Phase-locked scroll waves defy turbulence induced by negative filament tension

Scroll waves in a three-dimensional media may develop into turbulence due to negative tension of the filament. Such negative tension-induced instability of scrollwaves has been observed in the Belousov-Zhabotinsky reaction systems. Here we propose a method to restabilize scroll wave turbulence caused by negative tension in three-dimensional chemical excitable media using a circularly polarized (rotating) external field. The stabilization mechanism is analyzed in terms of phase-locking caused by the external field, which makes the effective filament tension positive. The phase-locked scrollwaves that have positive tension and higher frequency defy the turbulence and finally restore order. A linear theory for the change of filament tension caused by a generic rotating external field is presented and its predictions closely agree with numerical simulations

Decision-making for Autonomous Vehicles on Highway: Deep Reinforcement Learning with Continuous Action Horizon

Decision-making strategy for autonomous vehicles de-scribes a sequence of driving maneuvers to achieve a certain navigational mission. This paper utilizes the deep reinforcement learning (DRL) method to address the continuous-horizon decision-making problem on the highway. First, the vehicle kinematics and driving scenario on the freeway are introduced. The running objective of the ego automated vehicle is to execute an efficient and smooth policy without collision. Then, the particular algorithm named proximal policy optimization (PPO)-enhanced DRL is illustrated. To overcome the challenges in tardy training efficiency and sample inefficiency, this applied algorithm could realize high learning efficiency and excellent control performance. Finally, the PPO-DRL-based decision-making strategy is estimated from multiple perspectives, including the optimality, learning efficiency, and adaptability. Its potential for online application is discussed by applying it to similar driving scenarios.Comment: 9 pages, 10 figure

Effectiveness of triple inhalation therapy and non-invasive ventilation in the treatment of acute exacerbated chronic obstructive pulmonary disease

Purpose: To determine the clinical effectiveness of combining triple inhalation therapy with noninvasive ventilation in treating acute exacerbated chronic obstructive pulmonary disease (AECOPD).Methods: A total of 128 AECOPD patients admitted in the Department of Respiratory Medicine of our Hospital were involved in the study. Two groups of patients were used (64 patients per group). The study group was given triple inhalation therapy and non-invasive ventilation, while only non-invasive ventilation was given to the control group. The curative effects of the two treatments and their effects on arterial PaCO2 (partial pressure of carbon dioxide), pH and PaO2 (partial pressure of oxygen) were determined.Results: The study group showed significantly higher treatment effectiveness than the control group (p < 0.05). Post-treatment PaCO2, pH, PaO2, respiratory rate and heart rate differed significantly between the two groups (p < 0.05). Improvements in the five indices were more in the study group than in the control group (p < 0.05).Conclusion: Combining triple inhalation therapy with non-invasive ventilation in the treatment of AECOPD enhances therapeutic effect, improves pulmonary ventilation, and reduces side effects.Keywords: Chronic obstructive pulmonary disease, Acute exacerbation, Triple inhalation, Non-invasive ventilatio

Revisiting the proton synchrotron radiation in blazar jets: Possible contributions from X-ray to γ\gamma-ray bands

The proton synchrotron radiation is considered as the origin of high-energy emission of blazars at times. However, extreme physical parameters are often required. In this work, we propose an analytical method to study the parameter space when applying the proton synchrotron radiation to fit the keV, GeV, and very-high-energy emission of blazar jets. We find that proton synchrotron radiation can fit the high-energy hump when it peaks beyond tens GeV without violating basic observations and theories. For the high-energy hump peaked around GeV band, extreme parameters, such as a super-Eddington jet power and a very strong magnetic field, are required. For the high-energy hump peaked around keV band, if an acceptable parameter space can be found depends on the object's keV luminosity.Comment: Accepted for publication in Physical Review D (13 pages, 8 figures

Strong coupling of surface plasmon polaritons in monolayer graphene sheet arrays

Here we investigate theoretically and numerically the coupling between surface plasmon polaritons (SPPs) in monolayer graphene sheet arrays that have a period much smaller than the wavelength. We show that when the collective SPP is excited with an out-of-phase illumination, the beam tends to propagate toward the opposite direction of the Bloch momentum, reflecting a negative coupling between the constituent SPPs. In contrast, for in-phase illumination, the incident beam is split into two collective SPPs that are highly collimated and display low propagation loss. Moreover, the coupling between the individual SPPs results in a reduction of the modal wavelength of the SPP in comparison with that of a single graphene sheetThe work is partially supported by the Agency for Science, Technology, and Research (A*STAR) under Grant Nos. 0921450030, 0921540099, 0921540098 and the Ministry of Science and Technology of China under Grant No. 2009DFA52300 for China-Singapore collaborations. F. J. G.-V. acknowledges financial support from the European Research Council under Grant No. 290981 (PLASMONANOQUANTA