Fast, vision-based line-following schemes for micro-aerial vehicles in nuclear environments

Many nuclear power plants are reaching the end of their economic lifetime and the decommissioning of legacy nuclear facilities is an important challenge in the next few decades. Since the radiation level in these facilities is significant, autonomous robots are likely to be a large part of the solution. For this purpose, the mapping and inspection of nuclear facilities can be performed using autonomous Micro Aerial Vehicles (MAVs). Recently, there are many studies on achieving a stable and reliable MAV flight to perform accurate missions with high performance. Since human access is highly restricted in nuclear environments, conventional navigation systems are not able to complete many of the required tasks. Track follower MAVs have been implemented in many applications, such as water channels and railway inspections. To illustrate some of the issues involved, this research considers a line-following method and compares two attitude controllers. The approach can be divided into three tasks: 1) the image processing algorithm, 2) the path planning strategy and 3) attitude stabilisation. The environment under study contains a ground floor with predetermined red tracks over which the MAV moves. We explain each task briefly in the following. Image Processing: First, a colour detection algorithm is applied to form a thresholded image. To make the image smoother and to reduce noise effects, Dilation and Erosion algorithms are applied. Then, in each iteration, a vector is created by the boundary layer of the provided image. Morphological operations are performed to remove small discontinuities for each cluster. Here the goal is to find the midpoint of each cluster, known as keypoints. Finally, the obtained vector should be re-mapped to its original image matrix. Path Planning: The methodology for selecting the appropriate target point is to compare the distance between the keypoints and the target. For the take-off phase, the keypoint with smaller y in the image frame is chosen and, for the remaining iterations, the keypoint with lower distance to the target is selected. Then, the desired velocity in the body frame is calculated. Attitude Controller Design: Two controllers are considered to stabilise the attitude of the MAV. First, a linear Proportional-Integral-Derivative (PID) controller is selected. A linear PID control for yaw torque is derived. Subsequently, a conventional sliding surface for the yaw channel is defined and, by applying Lyapunov’s direct method, the stability of the system is guaranteed. The yaw control torque is derived as a function of the designed positive sliding gain. Finally, to avoid chattering phenomenon, one can approximate the discontinuous signum function with the hyperbolic one

Psychometric properties of the Farsi translation of the kiddie schedule for affective disorders and schizophrenia-present and lifetime version

BACKGROUND: Semi-structural clinical interviews are very important in the area of mental health research and services. There were no studies of the reliability and validity of the Farsi (Persian) version of Kiddie Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version (K-SADS-PL) in Iran. This study compares the results of face-to-face, semi-structural interview and clinical interview by a child and adolescent psychiatrist. METHOD: Subjects were 109 children and adolescents recruited to the child and adolescent psychiatry outpatient clinic of Hafez Hospital. Order of interview (in-psychiatrist or the semi-structural interview) was determined using random assignment within a counterbalanced framework. After, translation and back translation of K-SADS-PL, the Farsi version of K-SADS-PL was provided and used in the study. The interviewer was unaware of the child and adolescent psychiatrist diagnosis at the time of making the interview. Consensual validity, test-retest and inter-rater reliability, sensitivity, specifity, positive and negative predictive validity for the disorders were studied. RESULTS: Consensual validity of all of the psychiatric disorders was good to excellent. It was highest for panic disorder, conduct disorder, and simple phobia. Consensual validity of anorexia nervosa was 0.49. There was sufficient validity and test-retest and inter-rater reliability and good to excellent sensitivity and specifity and positive and negative predictive validity for nearly all of the disorders. Test-retest reliabilities of attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), and tic disorder were 0.81, 0.67, and 0.56; respectively. Inter-rater reliabilities of ADHD, and ODD were 0.69 and 0.69. Tic disorder, post traumatic disorder, panic disorder, and ADHD had the highest positive predictive validities. CONCLUSION: The Farsi version of K-SADS-PL is a valid and reliable interview instrument for use in assessing and diagnosising child and adolescent psychiatric disorders

Do spinal cord-injured individuals with stronger sense of coherence use different psychological defense styles?

Objectives: Although the importance of sense of coherence (SOC) and psychological defense mechanisms (PDMs) in the process of coping has been demonstrated, it has not yet been clarified whether individuals with stronger SOC use specific PDMs.Study design: Cross-sectional. Setting: Iran. Methods: Demographic and injury-related variables including injury level, time since injury, American Spinal Cord Association (ASIA) Scale and Spinal cord independence measure-III were collected among individuals with spinal cord injury (SCI). SOC was assessed by the Short-form Sense of Coherence Scale. PDMs were identified using 40-version of the Defense Style Questionnaire. Results: Neurotic defense style was the most commonly used style especially. The overall most commonly used PDM was 'rationalization', which was used by 95. Individuals with stronger SOC used more mature style (P=0.001, r=0.52), particularly 'humor' and 'suppression' mechanisms (P<0.0001 and 0.024, respectively). There was a negative correlation between stronger SOC and the use of immature defenses including passive aggression (P=0.001, r=-0.51), acting out (P=0.001, r=-0.48), isolation (P=0.009, r=-0.50), autistic fantasy (P=0.010, r=-0.30) and somatization (P<0.0001, r=-0.62). Married individuals had significantly stronger SOC (P=0.01). Age, gender, age at the time of injury incidence, time since injury, ASIA score and cause of injury were not determinants of SOC. Conclusion: In this study, PDMs, which are more probable to be used by individuals with stronger SOC, have been identified. Mature defenses including 'humor' and 'suppression' are used by stronger SOC more often, whereas immature mechanisms are less likely to be used. © 2016 International Spinal Cord Society

Recycling of Used Bottle Grade Poly Ethyleneterephthalate to Nanofibers by Melt-electrospinning Method

Used PET bottles disposal is an unsolved environmental problem, and there are many efforts for finding an applicable solution for it. Many researches have showed that the degradation rate of the polymers increase with the smaller size of fibers. This work was carried out to convert used PET bottles into nanofibers by melt-electrospinning method. Uncolored, washed and chipped PET bottles and the PET granule was used for experiments. The temperature of melted PET at extruder nozzle and spinning area were set in the range of 245-255 °Cand 200-235 °C respectively. The melting point of the polymer was determined by DSC. The potential difference was fixed at 25 kV and the distance between the nozzle and the collector were 3-9 cm. The morphology and fineness of produced fibers investigated by SEM. Although the producing fibers were not completely in the rang of nano-size fibers, but the results have showed that the nanofibers with diameter between 61- 93 nm can be achieved by the melt-electro spinning method. Comparing the effects of different flow rates of melting polymer as well as the distance between the nozzle to the collector have shown more proportion of finer fibers in flow rate less than 0.1 mL/min and the distance in the range of 3-5 cm. It was concluded however the melt electrospinning production of nanofibers has some difficulties but it can be considered as an applicable and environmental friendly way to recycling the used PET bottles so it can prevent more pollution of the environment