Design of a control architecture for an underwater remotely operated vehicle (ROV) used for search and rescue operations

summary:A control system architecture design for an underwater ROV, primarily Class I - Pure Observation underwater ROV is presented in this paper. A non-linear plant model was designed using SolidWorks 3D modeling tool and is imported to MATLAB as a 3D model. The non-linear modeled plant is linearized using the MATLAB linear analysis toolbox to have a linear approximate model of the system. The authors designed controllers for the linear plant model of underwater ROV. PID controllers are utilized as a controller of the modeled plant. The PID tuning tools by MATLAB are utilized to tune the controller of the plant model of underwater ROV. The researchers test the control design of underwater ROV using MATLAB Simulink by analyzing the response of the system and troubleshoot the control design to achieve the objective parameters for the control design of underwater ROV

An Inclusive Study on the Effect of Strain Rate on the Stress-Strain Behavior and the Undrained Shear Strength of Clay Soils in Kombolcha, Ethiopia

This research aims to study the effect of strain rate on the stress-strain association and shear strength of clay soils in Kombolcha, Ethiopia. Field and laboratory experimentations were conducted on 3 soil samples collected at 4.5m depth, considering the physical and engineering properties of the soil. Unconsolidated, undrained triaxial compression tests were performed under confining pressure on the specimens that were axially loaded at a rate of strain varying from 0.38mm/min to 1.14mm/min by taking 2 points above and below 1% of the specimen height. Stress-strain relations were developed under the stated different rates of strains to describe their effect. It was revealed that the strain rate effect was observed. By increasing the strain rate shifts the stress-strain curve upward, and the corresponding shear strength of the soil also increased under effective stress. Accordingly, the strain rate increased the shear parameters. The average angle of friction increased by 13.43%, 15.08%, 13.18%, and 14.33% when the rate of strain changed from 0.38 to 0.57mm/min, 0.57 to 0.76mm/min, 0.76 to 0.95mm/min, and 0.95 to 1.14mm/min respectively, while the average cohesion increased by 17.67%, 19.52%, 14.87%, and 16.48%. The failure at strain rate 1%/min of sample height (0.76mm/min) was uniformly distributed and there was uniform pore pressure distribution throughout the sample height. The effect is slightly more when the shear strength increased at the left side than at the right side. Average shear strength parameters such as cohesion and angle friction were recorded for strain rates from 0.57mm/min to 1.25mm/min specifically for the clay soils found in Kombolcha town, Ethiopia

Reducing repeat pregnancies in adolescence: applying realist principles as part of a mixed-methods systematic review to explore what works, for whom, how and under what circumstances

BACKGROUND: Previous research has demonstrated emotional, psychological and educational harm to young mothers following unintended conceptions. The UK has one of the highest rates of pregnancies in adolescence in Western Europe with a high proportion of these being repeat pregnancies, making it a topic of interest for public health policy makers, and health and social care practitioners. As part of a wider mixed-methods systematic review, realist principles were applied to synthesise evidence about interventions aiming to reduce repeat pregnancies in adolescence.METHODS: A multi-streamed, mixed-methods systematic review was conducted searching 11 major electronic databases and 9 additional databases from 1995 onwards, using key terms such as pregnancy, teen or adolescent. The principles of realist synthesis were applied to all included literature to uncover theories about what works, for whom, how and in what context. Initial theory areas were developed through evidence scoping, group discussion by the authors and stakeholder engagement to uncover context + mechanism = outcome (CMO) configurations and related narratives.RESULTS: The searches identified 8,664 documents initially, and 403 in repeat searches, filtering to 81 included studies, including qualitative studies, randomised controlled trials, quantitative studies and grey literature. Three CMO configurations were developed. The individual experiences of young mothers' triggered self-efficacy, notions of perceived risks, susceptibility and benefits of pregnancy, resulting in the adolescent taking control of their fertility and sexual encounters. The choice between motherhood and other goals triggered notions of motivations, resulting in the adolescent managing their expectations of motherhood and controlling their fertility and sexual encounters. Barriers and facilitators to accessing services triggered notions of connectedness and self-determination; resulting in interventions that are tailored so they are relevant to young persons, and improve access to services and engagement with the issue of pregnancy in adolescence.CONCLUSIONS: Pregnancy in adolescence is a complex issue with many factors to consider. The conceptual platform described here could help guide policy makers and professionals towards a number of areas that need to be attended to in order to increase the likelihood of an intervention working to prevent rapid repeat pregnancy in adolescence.TRIAL REGISTRATION: PROSPERO CRD42012003168

Person detection and tracking from aerial videos

In this study, a system that can detect and locate humans in video recordings collected by an unmanned aerial vehicle (UAV) was developed. Several machine vision algorithms were implemented. Lucas and Kanade optic flow computation and YUV color space conversion were used for feature point selection, and Mean-Shift clustering in feature space for image segmentation. Histogram of Oriented Gradients (HOG), Haar, and Speeded Up Robust Features (SURF) were used for feature extraction, while Support Vector Machines (SVM) and Adaptive Boosting (AdaBoost) were utilized for training and classification. Kalman filter was employed for tracking humans. The Person Detection and Tracking from Aerial Videos (PDTrAV system was tested on videos taken under different weather conditions and was able to successfully detect and tract people in them. System tests, however, indicated more false positives and false negatives than true positives. A minimum threshold for the ratio of the blob area and its bounding box area was enforced in order to reduce the number of false positives, which were attributed to diagonal lines or edges that were detected as people. The use of Haar-like features attained the best recall at 32.3925% while the use of HOG features attained the best precision at 24.5945% While improvements can be done to make the system suitable for any real world application, this study has proven that it is possible to detect humans from an aerial perspective using fewer and more cost effective resources. The system was able to detect humans in aerial videos taken using an ordinary digital camera. Further improvements on the Mean-Shift clustering, Kalman filter, and the feature extraction methods are recommended for better performance of the system. For the Mean-Shift Algorithm, bandwidth estimators can be used since the system only used a constant bandwidth input. Since the Kalman filter used in the system can only estimate constant velocity and location of the blobs, adaptive Kalman filter can be used to have more accurate estimates when the velocity of the blobs or of the camera becomes time-varying. For HOG and Haar feature extraction, a larger and more unique dataset should be used to have more features to compare with. For SURF extraction, the size of the dataset set, the number of clusters in the visual codebook, the number of octaves and scale levels, and the threshold value should be varied in order to determine the most suitable values for a certain application

Do Emotions Spark Interest in Alternative Tobacco Products?

BackgroundExposure to advertisements for tobacco products and tobacco warning labels evokes emotions. This study evaluated the association of discrete positive and negative emotions with interest in alternative tobacco products.MethodIn 2013, 1,226 U.S. adult nonsmokers and current smokers viewed advertisements for moist snuff, snus, and electronic cigarettes (e-cigarettes) with various warning labels and then indicated their emotional responses in terms of anger, anxiety, sadness, guilt, disgust, discouragement, hope, and contentment. Outcomes were openness to using moist snuff, snus, and e-cigarettes in the future and interest in a free sample of each product. Data were analyzed in 2016.ResultsHope was positively associated with openness and interest across all alternative tobacco products as was contentment for moist snuff and snus. Anger was negatively associated with openness to moist snuff and e-cigarettes, disgust negatively to moist snuff and snus, and anxiety negatively to e-cigarettes. Being a current smoker, ever trying a corresponding product, being male, and younger age were associated with greater openness to and interest in moist snuff and snus. For e-cigarettes, being a current smoker, ever trying e-cigarettes, and being female were associated with greater openness, and being a current smoker was associated with greater odds of selecting a free sample.ConclusionsPositive emotions, particularly hope, were consistently positively associated with interest in alternative tobacco products. Hope is widely used by tobacco and e-cigarette companies to advertise their products. Antitobacco messages should aim to lower hope associated with tobacco products but increase hope for cessation or life without tobacco