Robust Attitude Control of an Agile Aircraft Using Improved Q-Learning

Attitude control of a novel regional truss-braced wing (TBW) aircraft with low stability characteristics is addressed in this paper using Reinforcement Learning (RL). In recent years, RL has been increasingly employed in challenging applications, particularly, autonomous flight control. However, a significant predicament confronting discrete RL algorithms is the dimension limitation of the state-action table and difficulties in defining the elements of the RL environment. To address these issues, in this paper, a detailed mathematical model of the mentioned aircraft is first developed to shape an RL environment. Subsequently, Q-learning, the most prevalent discrete RL algorithm, will be implemented in both the Markov Decision Process (MDP) and Partially Observable Markov Decision Process (POMDP) frameworks to control the longitudinal mode of the proposed aircraft. In order to eliminate residual fluctuations that are a consequence of discrete action selection, and simultaneously track variable pitch angles, a Fuzzy Action Assignment (FAA) method is proposed to generate continuous control commands using the trained optimal Q-table. Accordingly, it will be proved that by defining a comprehensive reward function based on dynamic behavior considerations, along with observing all crucial states (equivalent to satisfying the Markov Property), the air vehicle would be capable of tracking the desired attitude in the presence of different uncertain dynamics including measurement noises, atmospheric disturbances, actuator faults, and model uncertainties where the performance of the introduced control system surpasses a well-tuned Proportional–Integral–Derivative (PID) controller

Sound speed and its attenuation in the Persian Gulf

High quality of commercial and research uses of acoustical methods in fisheries need to have enough information about sound speed variations, Ray tracing and attenuation rate in the water. In this paper we focused on sound speed variation with depth versus physical properties of Bandar Dayer waters (NE of Farsi island and about 50 kilometers south of Delware; 28.2 N & 50.58 E) and calculation of attenuation rate. Importance of this area is for the Gulf currents, which cover this region. The results of this research show that up to 11 meters depth sound speed remain constant while depth increases and temperature decreases. After this depth sound speed decreases which is for decreasing in salinity and temperature. Sound attenuation profiles show that the most attenuation rate is at 17 to 27 meters depth

Lunar Flashlight: Mapping Lunar Surface Volatiles Using a Cubesat

Water ice and other volatiles may be located in the Moon's polar regions, with sufficient quantities for in situ extraction and utilization by future human and robotic missions. Evidence from orbiting spacecraft and the LCROSS impactor suggests the presence of surface and/or nearsurface volatiles, including water ice. These deposits are of interest to human exploration to understand their potential for use by astronauts. Understanding the composition, quantity, distribution, and form of water/H species and other volatiles associated with lunar cold traps is identified as a NASA Strategic Knowledge Gap (SKG) for Human Exploration. These polar volatile deposits could also reveal important information about the delivery of water to the Earth- Moon system, so are of scientific interest. The scientific exploration of the lunar polar regions was one of the key recommendations of the Planetary Science Decadal Survey. In order to address NASA's SKGs, the Advanced Exploration Systems (AES) program selected three lowcost 6-U CubeSat missions for launch as secondary payloads on the first test flight (EM1) of the Space Launch System (SLS) scheduled for 2017. The Lunar Flashlight mission was selected as one of these missions, specifically to address the SKG associated with lunar volatiles. Development of the Lunar Flashlight CubeSat concept leverages JPL's Interplanetary Nano- Spacecraft Pathfinder In Relevant Environment (INSPIRE) mission, MSFC's intimate knowledge of the Space Launch System and EM-1 mission, small business development of solar sail and electric propulsion hardware, and JPL experience with specialized miniature sensors. The goal of Lunar Flashlight is to determine the presence or absence of exposed water ice and its physical state, and map its concentration at the kilometer scale within the permanently shadowed regions of the lunar south pole. After being ejected in cislunar space by SLS, Lunar Flashlight deploys its solar panels and solar sail and maneuvers into a low-energy transfer to lunar orbit. The solar sail and attitude control system work to bring the satellite into an elliptical polar orbit spiraling down to a perilune of 30-10 km above the south pole for data collection. Lunar Flashlight uses its solar sail to shine reflected sunlight into permanently shadowed regions, measuring surface albedo with a four-filter point spectrometer at 1.1, 1.5 1.9, and 2.0 microns. Water ice will be distinguished from dry regolith from these measurements in two ways: 1) spatial variations in absolute reflectance (water ice is much brighter in the continuum channels), and 2) reflectance ratios between absorption and continuum channels. Derived reflectance and reflectance ratios will be mapped onto the lunar surface in order to distinguish the composition of the PSRs from that of the sunlit terrain. Lunar Flashlight enables a low-cost path to in-situ resource utilization (ISRU) by identifying operationally useful deposits (if there are any), which is a game-changing capability for expanded human exploration

Pulmonary metastases: Results of surgical resection in 60 cases: Treatment modalities other than surgery are needed

Pulmonary metastases occur in 30 of all oncology patients. Surgical resection of lung metastases is a widely accepted procedure but long-term results are disappointing with a 5-year survival rate of 20-40 and the results vary with the histologic type of the primary tumor. Due to unavailability of any study regarding pulmonary metastasectomy in Iran and emergence of new treatment modalities, reassessment of our current practices is essential. We performed a retrospective study of 60 cases of pulmonary metastasectomy during a 5-year period in one of the major thoracic surgery centers in Tehran (Imam Khomeini Hospital). Bilateral metastases were present in 23 of cases, number of metastases in each patient ranged from 1-12. Average disease-free interval was 12 months, pneumonectomy rate was 21.7 mostly as a second or third attempt and finally, recurrence or death following initial metastasectomy occurred in 12-18 months in most patients. These results confirm that surgery remains unsuccessful in obtaining long-term survival or cure in most patients with pulmonary metastases and treatment strategies other than surgery, such as radiofrequency ablation are needed to avoid performing multiple operations in these patients and improving their quality of life. © 2007 Tehran University of Medical Sciences. All rights reserved

Astrocytic Abnormalities in Schizophrenia

Astrocytes are glial cells in the central nervous system (CNS), which contribute to CNS health and disease by participating in homeostatic, structural, and metabolic processes that play an essential role in facilitating synaptic transmission between neurons. Schizophrenia (SCZ) is a neuropsychiatric disorder associated with various positive and negative behaviors and interruption of executive function and cognition thought to be due partly to aberrations in signaling within neural networks. Recent research has demonstrated that astrocytes play a role in SCZ through various effects, including influencing immune system function, altering white matter, and mediating changes in neurotransmitters. Astrocytes are also known to play a role in inducing SCZ-associated changes in neuroplasticity, which includes alterations in synaptic strength and neurogenesis. Also, astrocyte abnormalities are linked to neurobehavioral impairments seen at the clinical level. The present chapter details general information on SCZ. It highlights the role of astrocytes in SCZ at molecular and behavioral levels, including neural changes seen in the disease, and the therapeutic implications of targeting astrocytes in SCZ

Opiate Dependants’ Experiences of the Established Therapeutic Relationship in Methadone Centers: Qualitative Study

Abstract: Background & Aims: Methadone maintenance therapy is one of the treatment choices for opiate users. Understanding opiate dependants’ experiences of their treatment period is important for continuing the treatment with methadone and assessing their experiences may help to revise the standards of methadone centers and thus to improve the quality of treatment. This study aims to describe the structure and essence of opiate dependants’ experiences with methadone centers during treatment. Method: It was a qualitative phenomenological approach in which participants were selected from opiate dependants referred to methadone centers in Kerman city in 2007 by applying purposive sampling continued until data saturation and obtaining a sample size of 32 participants. Data were collected by in-depth interviews. Colaize' s Method was applied for data analysis. The rigor of the present study was based on transferability and credibility. Results: In whole, 26 themes were extracted and put into structural components. The structural components were put into topical components including: 1- positive therapeutic alliance 2- negative therapeutic alliance and 3- therapeutic alliance requests. These components show the basic structure of participants’ experiences of therapeutic relationship in methadone centers. Conclusion: Client – based strategy in methadone clinics, not only leads to a positive therapeutic alliance, but can persuade patients to continue their treatment programs for long time period. Establishing a good relationship with patients in methadone centers during treatment procedure is an effective way to meet the goals of methadone maintenance treatment. Keywords: Methadone, Experiences, Professional-patient Relation, Qualitative research, Opiate dependenc

Psychosis in Three Patients with Vitiligo

Abstract: Psychotic disorders have been observed in association with some autoimmune disorders. Moreover, autoimmune mechanisms have been recently considered in evaluation of schizophrenia spectrum disease managements. Vitiligo is one of the autoimmune diseases, but there is no report of vitiligo association with psychosis. We report three patients with vitiligo and schizophrenia spectrum disease that are indicative of the role of autoimmunity in psychosis. Moreover, unusual manifestation and poor response to treatment in the reported cases show that autoimmunity can complicate the prognosis of psychosis. Keywords: Vitiligo, Autoimmune, Schizophrenia, Psychosi

Rare Variant of Lycanthropy and Ecstasy: Case Report

Abstract: Lycanthropy is an unusual belief or delusion in which the patient thinks that he/she has been transformed into an animal. In rare cases, the patient believes that another person has been transformed into an animal. In this case report, a patient who had an uncommon variant of lycanthropy is introduced. The patient’s symptoms had appeared after consumption of ecstasy. This shows the occurrence of uncommon and rare psychosis after ecstasy drug use especially in susceptible patients to schizophrenia. Ecstasy can induce paranoid psychosis similar to schizophrenia. It seems that in the presented case, ecstasy had a role in the incidence of the underlying suceptibility of the patient to schizophrenia. Keywords: Lycanthropy, Methylenedioxymethamphetamine (MDMA

Iterative Learning Control to Enhance Accuracy of Repetitive Maneuvers for Aerial Robots

In this study, in order to enhance the accuracy of tracking repetitive maneuvers in Unmanned Aerial Vehicles (UAVs), a learning-based control scheme is proposed. At the outset, the controller is designed based on the sliding mode control (SMC) technique. In addition, the offline PD-type memory-based iterative learning control (ILC) is used along with SMC. The purpose of using ILC method is to reduce the effect of system uncertainty on the controller and decrease repetitive errors by adjusting the input control signal to dynamics and thus, to increase the reliability of following the desired path. In the ILC scheme, the error of states is saved during the maneuvers which will be used in the subsequent iteration. Also, in order to increase flexibility of the new control structure, ILC-SMC, a multilayer perceptron (MLP) has been developed. This network is designed to extend the control signal, generated by ILC, to similar maneuvers. The inputs of this neural network are the initial conditions for starting the maneuver and the output of the neural network is a gain that is multiplied by the stored control signal ILC and produces a new control signal. This generated signal will be suitable for similar maneuvers. The Levenberg–Marquardt (LM) algorithm has been used to train the multilayer perceptron artificial neural network. This method was then used in loop maneuvers. In this simulation, the difference between the maneuvers was in the acceleration of the maneuver, the radius of the maneuver, and the initial speed of the maneuver. This reduced the tracking error for similar maneuvers without performing the training process for the ILC control component. The presented control scheme is applied to a quadrotor aerial vehicle for tracking desired trajectories and it is shown that the vehicle is able to follow the desired trajectory better than the conventional SMC in the presence of uncertainties

Numerical and Experimental Study of a Wing Combined with Wing Grids in Low Reynolds Number Flows

One of the reasons for the increase in induced drag is the vortices created at the wing tip, which has a significant effect on reducing aerodynamic efficiency. Therefore, in order to reduce vortices and the induced drag as well as to improve the aerodynamic performance, the use of wing grid is recommended. Wing grids perform better at low Reynolds numbers, and combination of parameters such as taper ratio, aspect ratio, and twist has a better effect on wing performance and reducing turbulence intensity and induced drag. The purpose of this paper is to improve the aerodynamic performance of compound wing using the wing grids. In this study, the numerical and experimental approaches have been used to investigate the effect of these parameters and also, two key parameters: the grid dihedral angle and sweep angle. Also, a force balance test has been performed for force analysis and numerical solution validation. Wing grid dihedral angle decreases induced drag by increasing the space between separated tip vortices and prevents reinforcing effects due to superposition. On the other hand, dihedral angle should be arranged to increase the aerodynamic efficiency. In other words, increase in dihedral angle may defect the overall performance of the wing. The optimum configuration is found to be symmetric, where the dihedral distribution with a 40° angle for the first grid is reduced gradually to a value of -20° for the last one. In addition, sweep angle distribution for the obtained optimized dihedral angle is also investigated. Initially, each grid span is decreased from the first grid to the last at a constant rate. This increases the sweep angle and enhances the aerodynamic efficiency by 15%. Furthermore, the span of the side grids is reduced from the middle grid and marching the wing leading and trailing edges. Elliptical wing configuration has also been shown to increase aerodynamic efficiency by approximately 50%