Distributed navigation of multi-robot systems for sensing coverage

A team of coordinating mobile robots equipped with operation specific sensors can perform different coverage tasks. If the required number of robots in the team is very large then a centralized control system becomes a complex strategy. There are also some areas where centralized communication turns into an issue. So, a team of mobile robots for coverage tasks should have the ability of decentralized or distributed decision making. This thesis investigates decentralized control of mobile robots specifically for coverage problems. A decentralized control strategy is ideally based on local information and it can offer flexibility in case there is an increment or decrement in the number of mobile robots. We perform a broad survey of the existing literature for coverage control problems. There are different approaches associated with decentralized control strategy for coverage control problems. We perform a comparative review of these approaches and use the approach based on simple local coordination rules. These locally computed nearest neighbour rules are used to develop decentralized control algorithms for coverage control problems. We investigate this extensively used nearest neighbour rule-based approach for developing coverage control algorithms. In this approach, a mobile robot gives an equal importance to every neighbour robot coming under its communication range. We develop our control approach by making some of the mobile robots playing a more influential role than other members of the team. We develop the control algorithm based on nearest neighbour rules with weighted average functions. The approach based on this control strategy becomes efficient in terms of achieving a consensus on control inputs, say heading angle, velocity, etc. The decentralized control of mobile robots can also exhibit a cyclic behaviour under some physical constraints like a quantized orientation of the mobile robot. We further investigate the cyclic behaviour appearing due to the quantized control of mobile robots under some conditions. Our nearest neighbour rule-based approach offers a biased strategy in case of cyclic behaviour appearing in the team of mobile robots. We consider a clustering technique inside the team of mobile robots. Our decentralized control strategy calculates the similarity measure among the neighbours of a mobile robot. The team of mobile robots with the similarity measure based approach becomes efficient in achieving a fast consensus like on heading angle or velocity. We perform a rigorous mathematical analysis of our developed approach. We also develop a condition based on relaxed criteria for achieving consensus on velocity or heading angle of the mobile robots. Our validation approach is based on mathematical arguments and extensive computer simulations

Effectiveness of third-class biologic treatment in crohn’s disease : A multi-center retrospective cohort study

Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Background: Multiple studies have described the effectiveness of ustekinumab (UST) and vedolizumab (VDZ) in patients with Crohn’s disease (CD) failing anti-Tumor necrosis factors (TNFs); however, the effectiveness of VDZ or UST as a third-class biologic has not yet been described. Aims and Methods: In this retrospective multicenter cohort study, we aimed to investigate the effectiveness of VDZ and UST as a third-class biologic in patients with CD. Results: Two-hundred and four patients were included; 156/204 (76%) patients received VDZ as a second-and UST as a third-class therapy (group A); the remaining 48/204 (24%) patients received UST as a second-and VDZ as a third-class therapy (group B). At week 16–22, 87/156 (55.5%) patients and 27/48 (56.2%) in groups A and B, respectively, responded to treatment (p = 0.9); 41/156 (26.2%) and 15/48 (31.2%) were in clinical remission (p = 0.5). At week 52; 89/103 (86%) patients and 25/29 (86.2%) of the patients with available data had responded to third-class treatment in groups A and B, respectively (p = 0.9); 31/103 (30%) and 47/29 (24.1%) were in clinical remission (p = 0.5). Conclusion: Third-class biological therapy was effective in more than half of the patients with CD. No differences in effectiveness were detected between the use of VDZ and UST as a third-class agent.Peer reviewe

Decentralized control of mobile robotic sensor network

The self deployment of a decentralized mobile sensor network has been addressed in this thesis. The mobile robotic sensors are self deployed in the form of a blanket over a bounded and connected unknown two dimensional region. The main objective is to fully track and to cover the arbitrary unknown region (meeting assumptions) with minimum number of mobile robotic sensors moving under decentralized control. The issue of connectivity has also been considered during final deployment of mobile robotic sensors. An algorithm with decentralized control law has been developed to self deploy the mobile robotic sensors into a triangular lattice pattern ensuring optimization. The optimization of deployment in terms of minimum number of sensors ensuring 1-coverage and 6-connectivity (wherever possible) has been considered during final deployment of mobile robotic sensors over the unknown region. A special consideration in continuation to the past work has been taken in order to remove the redundant placement of mobile robotic sensors on the boundary of the region and to fully track all the segments of the boundary of the region. The control action for velocity and heading of mobile robotic sensors is based on simple nearest neighbourhood rules derived from swarm intelligence. The algorithm also uses the concept of stable quotient system of the decentralized control system during line forming mode inside the region. A number of numerical simulations while changing the arbitrary region have been done in order to validate the control algorithm. As compared to the past work, the boundary moving mobile robotic sensors fully explore every segment of the boundary of the unknown region, and redundantly placed mobile robotic sensor on each of the line forming mode inside the region has been removed

Distributed navigation of multi-robot systems for sensing coverage

A team of coordinating mobile robots equipped with operation specific sensors canperform different coverage tasks. If the required number of robots in the team isvery large then a centralized control system becomes a complex strategy. Thereare also some areas where centralized communication turns into an issue. So, ateam of mobile robots for coverage tasks should have the ability of decentralized ordistributed decision making. This thesis investigates decentralized control of mobilerobots specifically for coverage problems. A decentralized control strategy is ideallybased on local information and it can offer flexibility in case there is an incrementor decrement in the number of mobile robots. We perform a broad survey of theexisting literature for coverage control problems. There are different approachesassociated with decentralized control strategy for coverage control problems. Weperform a comparative review of these approaches and use the approach based onsimple local coordination rules. These locally computed nearest neighbour rules areused to develop decentralized control algorithms for coverage control problems.We investigate this extensively used nearest neighbour rule-based approach fordeveloping coverage control algorithms. In this approach, a mobile robot gives anequal importance to every neighbour robot coming under its communication range.We develop our control approach by making some of the mobile robots playinga more influential role than other members of the team. We develop the controlalgorithm based on nearest neighbour rules with weighted average functions. Theapproach based on this control strategy becomes efficient in terms of achieving aconsensus on control inputs, say heading angle, velocity, etc.The decentralized control of mobile robots can also exhibit a cyclic behaviourunder some physical constraints like a quantized orientation of the mobile robot.We further investigate the cyclic behaviour appearing due to the quantized controlof mobile robots under some conditions. Our nearest neighbour rule-based approachoffers a biased strategy in case of cyclic behaviour appearing in the team of mobilerobots.We consider a clustering technique inside the team of mobile robots. Our decentralizedcontrol strategy calculates the similarity measure among the neighboursof a mobile robot. The team of mobile robots with the similarity measure basedapproach becomes efficient in achieving a fast consensus like on heading angle orvelocity. We perform a rigorous mathematical analysis of our developed approach.We also develop a condition based on relaxed criteria for achieving consensus onvelocity or heading angle of the mobile robots. Our validation approach is based onmathematical arguments and extensive computer simulations

To trust or not to trust? Faith issues in psychopharmacological prescribing

Aims and method: To ascertain attitudes, awareness, knowledge and variations in prescribing habits of psychiatrists when addressing issues of faith, culture and dietary requirements (in keeping with the General Medical Council\u27s and the Royal College of Psychiatrists\u27 guidelines), and how these may affect the trust in doctor-patient relations. We undertook a cross-sectional postal survey aimed at clinicians in South West Yorkshire Mental Health Trust. Results: We obtained 38 responses (40% of the total number of questionnaires sent out) from two mailshots. Although the majority of respondents indicated that they were aware of the presence of potentially forbidden animal-derived ingredients in medication, only half expressed the view that a discussion regarding the above should take place prior to prescribing such medication. Clinical implications: Diversity training combined with taking a genuine interest in patients\u27 wishes will not only minimise \u27mistrust\u27 but also facilitate prescribing in a therapeutic relationship