The Voltage Regulation of Boost Converters using Dual Heuristic Programming

In this paper, a dual heuristic programming controller is proposed to control a boost converter. Conventional controllers such as proportional-integral-derivative (PID) or proportional-integral (PI) are designed based on the linearized small-signal model near the operating point. Therefore, the performance of the controller during start-up, load change, or input voltage variation is not optimal since the system model changes by varying the operating point. The dual heuristic programming controller optimally controls the boost converter by following the approximate dynamic programming. The advantage of the DHP is that the neural network–based characteristic of the proposed controller enables boost converters to easily cope with large disturbances. A DHP with a well-trained critic and action networks can perform as an optimal controller for the boost converter. To compare the effectiveness of the traditional PI-based and the DHP boost converter, the simulation results are provided

Autonomous Control of a Line Follower Robot Using a Q-Learning Controller

In this paper, a MIMO simulated annealing (SA)-based Q-learning method is proposed to control a line follower robot. The conventional controller for these types of robots is the proportional (P) controller. Considering the unknown mechanical characteristics of the robot and uncertainties such as friction and slippery surfaces, system modeling and controller designing can be extremely challenging. The mathematical modeling for the robot is presented in this paper, and a simulator is designed based on this model. The basic Q-learning methods are based pure exploitation and the ε -greedy methods, which help exploration, can harm the controller performance after learning completion by exploring nonoptimal actions. The simulated annealing–based Q-learning method tackles this drawback by decreasing the exploration rate when the learning increases. The simulation and experimental results are provided to evaluate the effectiveness of the proposed controller

Peripheral Venous Malformations with a Dominant Outflow Vein: Results of Ethanol Embolization

Venous malformations are the most common form of symptomatic vascular malformations. VM s could classify into low-flow lesions (VMs) and high-flow lesions (AVMs). For low-flow venous lesions, direct percutaneous puncture with injection of sclerosing agents (sclerotherapy) has been described as a successful therapy. In this article, we want to introduce a patient who treated with ethanol sclerotherapy for VM located in the right flank. The patients were a 35-year-old man with right flank mass, skin discoloration and hemorrhagic foci. Color Doppler ultrasonography showed low flow vascular malformation while Magnetic Resonance Imaging (MRI) showed that the mass contained fat tissue with branching tubular signal void structures inside. The draining vein was first coiled via tortuous venous malformation vessels access and then VM was embolized.Under ultrasonographic guide, direct puncture of one branches of venous malformation was performed, and contrast media were injected. The patient underwent the sclerotherapy every month for four consecutive months. The patient was followed up for a year, and clinical examination revealed 40-50% size reduction of the lesion while no bleeding was detected from the lesion during the follow-up period. Sclerotherapy with ethanol is a useful method for embolizing VMs

Nanoclay Reinforced Polyethylene Composites: Effect of Different Melt Compounding Methods

Nanoclay (NC) reinforced high-density polyethylene (HDPE) composites were prepared by different melt compounding methods using (1) a single screw extruder (SSE), (2) twin screw extruder (TSE), (3) a combination of SSE and extensional flow mixer (EFM), and (4) a bowl mixer masterbatch method (MB). PE-grafted maleic anhydride (PE-eta-MA) was used as a compatibilizer. EFM increased complex melt viscosity (eta{*}) of the HDPE/NC composites as compared to the neat HDPE and also provided a better interaction between HDPE and NC to create slightly lower melt eta{*} as compared to MB and PE-g-MA composites. The low viscosity melt behavior of the pure HDPE changes to more solid like melt behavior in the PE-eta-MA HDPE/NC composites in the low frequency (omega) region. PE-eta-MA1EFM method exhibited better impact strength compared to the other HDPE/NC composites. Using the PE-eta-MA and masterbatch compounding methods had a beneficial role in improving mechanical properties. (C) 2016 Society of Plastics Engineer