Robust laser positioning in a mobile robot machine vision system

Problem. Laser scanning devices are widely used in Machine Vision Systems (MVS) of an autonomous mobile robot for solving SLAM problems. One of the concerns with MVS operation is the ability to detect relatively small obstacles. This requires scanning a limited sector within the field of view or even focusing on a specific point of space. The accuracy of the laser beam positioning is hampered by various kinds of uncertainties both due to the model simplifying and using inaccurate values of its parameters, as well as lacking information about perturbations. Goal. This paper presents the improvement of the MVS, described in previous works of the authors, by robust control of the DC motor, which represents the Positioning Laser drive. Methodology. For this purpose, a DC motor model is built, taking into account the parametric uncertainty. A robust digital PD controller for laser positioning is designed, and a comparative evaluation of the robust properties of the obtained control system with a classical one is carried out. The PWM signal formation by the microcontroller and processes in the H-bridge are also taken into account. Results. The obtained digital controller meets the transient process and accuracy requirements and combines the simplicity of a classic controller with a weak sensitivity to the parametric uncertainties of the drive model. Originality. The originality of the paper is in its focus on the MVS of the autonomous mobile robot developed by the authors. Practical value. The implementation of the MVS with the proposed controller will increase the reliability of obstacles detection within a robot field of view and the accuracy of environment mapping.

A Review of Recent Patents on Structures Related to Tracheal Stents

Background: The trachea is an important part of the respiratory system. Long-term airway diseases and the effects of human physiological conditions can cause trachea stenosis. This will seriously affect patients’ physical health. Tracheal stents can provide durable support by means of dilating the narrowed area; they can effectively relieve the patient's breathing difficulties, which is of value that is more practical. Objective: To meet the vital requirements for better adaptation to the human airway environment and prevent complications associated with stent placement, the construction and materials of tracheal stents have been improved constantly. Methods: This paper investigates various representative patents related to the tracheal stent. The structure type, placement method and applications situation of these tracheal stents are discussed. Results: The characteristics of different types of tracheal stents are analyzed. This paper analyzes the main problems in its development. The solutions to the issues and the current and future research on tracheal stents are discussed. Conclusion: The tracheal stents are classified into metal stent, silicone stent, biodegradable stent and hybrid material stent. Further improvements are needed in the aspects of structural design, safety, applicability, biocompatibility, algorithm of drive model of tracheal stent. More related patents about tracheal stents need to be developed.

Backstepping Control of Switched Reluctance Motor with Artificial Neural Network based Flux Estimator

The paper presents a new approach to design a nonlinear controller for switched reluctance motors (SRMs) based on backstepping technique and artificial neuron network (ANN) in flux estimator. Backstepping controller with an ANN flux estimator will be applied for controlling SRMs which have a nonlinear drive model. The ANN flux estimator was trained off-line using backpropagation algorithm. The stability of the closed control loop was analyzed and proved accroding to the Lyapunov stability standard. The numerical simulation results confirmed the accuracy of the estimator and the quality of the backstepping control system.

Stress and the Well-being of Nurses: an Investigation using the Demands-Resources- Individual Effects (DRIVE) model and the Well-being Process Questionnaire (WPQ).

Previous research shows that nurses have high levels of stress, but less is known about their well-being. The present research used an adapted version of the Demands-Resources-Individual Effects (DRIVE) model to investigate these areas. The Well-Being Process Questionnaire (WPQ), which consists of single items derived from longer scales, was also used. One hundred and seventy-seven British nurses (160 female, 17 male) participated in an online survey. The results showed that work characteristics could be grouped into three factors (resources; demands; and role/change/bullying), as were personality scores (positive personality; openness, agreeable, conscientious; and extraversion, emotional stability). Coping (positive and negative coping) and outcomes (positive and negative outcomes, and positive and negative job appraisals) had a two-factor solution. Results from logistic regressions showed that well-being outcomes were predicted by high positive personality and low negative coping. Positive job appraisals were predicted by high resources and low demands. These findings confirm that the use of the DRIVE model and a single short item measuring instrument can quickly provide information about factors predicting the well-being of nurses.

Holocentric Chromosomes Probably Do Not Prevent Centromere Drive in Cyperaceae

Centromere drive model describes an evolutionary process initiated by centromeric repeats expansion, which leads to the recruitment of excess kinetochore proteins and consequent preferential segregation of an expanded centromere to the egg during female asymmetric meiosis. In response to these selfish centromeres, the histone protein CenH3, which recruits kinetochore components, adaptively evolves to restore chromosomal parity and counter the detrimental effects of centromere drive. Holocentric chromosomes, whose kinetochores are assembled along entire chromosomes, have been hypothesized to prevent expanded centromeres from acquiring a selective advantage and initiating centromere drive. In such a case, CenH3 would be subjected to less frequent or no adaptive evolution. Using codon substitution models, we analyzed 36 CenH3 sequences from 35 species of the holocentric family Cyperaceae. We found 10 positively selected codons in the CenH3 gene [six codons in the N-terminus and four in the histone fold domain (HFD)] and six branches of its phylogeny along which the positive selection occurred. One of the positively selected codons was found in the centromere targeting domain (CATD) that directly interacts with DNA and its mutations may be important in centromere drive suppression. The frequency of these positive selection events was comparable to the frequency of positive selection in monocentric clades with asymmetric female meiosis. Taken together, these results suggest that preventing centromere drive is not the primary adaptive role of holocentric chromosomes, and their ability to suppress it likely depends on their kinetochore structure in meiosis.

Exploring the Awareness, Motivations, and Coping Strategies of Problematic Internet Users

This paper presents a systematic review that covers internet addiction and wellbeing studies on adults; followed by a semi-structured interview of a group of 6 problematic internet adult users, analysed through thematic analysis. The interview questions explore motives, awareness level and coping strategies of problematic internet users. The systematic review results are categorised based on DRIVE model and indicate gaps in the literature on internet addiction studies and suggests a holistic direction of studying wellbeing. The interviews resulted in 6 themes that reflected the user’s awareness of the consequences of problematic internet use, coping strategies when there is a high information overload, controlling internet attachment, causes of excessive internet use, preferred using time and psychological effect after spending long hours online.