Hybrid spiral-dynamic bacteria-chemotaxis algorithm with application to control two-wheeled machines

This paper presents the implementation of the hybrid spiral-dynamic bacteria-chemotaxis (HSDBC) approach to control two different configurations of a two-wheeled vehicle. The HSDBC is a combination of bacterial chemotaxis used in bacterial forging algorithm (BFA) and the spiral-dynamic algorithm (SDA). BFA provides a good exploration strategy due to the chemotaxis approach. However, it endures an oscillation problem near the end of the search process when using a large step size. Conversely; for a small step size, it affords better exploitation and accuracy with slower convergence. SDA provides better stability when approaching an optimum point and has faster convergence speed. This may cause the search agents to get trapped into local optima which results in low accurate solution. HSDBC exploits the chemotactic strategy of BFA and fitness accuracy and convergence speed of SDA so as to overcome the problems associated with both the SDA and BFA algorithms alone. The HSDBC thus developed is evaluated in optimizing the performance and energy consumption of two highly nonlinear platforms, namely single and double inverted pendulum-like vehicles with an extended rod. Comparative results with BFA and SDA show that the proposed algorithm is able to result in better performance of the highly nonlinear systems

A two-wheeled machine with a handling mechanism in two different directions

Despite the fact that there are various configurations of self-balanced two-wheeled machines (TWMs), the workspace of such systems is restricted by their current configurations and designs. In this work, the dynamic analysis of a novel configuration of TWMs is introduced that enables handling a payload attached to the intermediate body (IB) in two mutually perpendicular directions. This configuration will enlarge the workspace of the vehicle and increase its flexibility in material handling, objects assembly and similar industrial and service robot applications. The proposed configuration gains advantages of the design of serial arms while occupying a minimum space which is unique feature of TWMs. The proposed machine has five degrees of freedoms (DOFs) that can be useful for industrial applications such as pick and place, material handling and packaging. This machine will provide an advantage over other TWMs in terms of the wider workspace and the increased flexibility in service and industrial applications. Furthermore, the proposed design will add additional challenge of controlling the system to compensate for the change of the location of the COM due to performing tasks of handling in multiple directions

Outcomes Following Vascular and Endovascular Procedures Performed During the First COVID-19 Pandemic Wave

\ua9 2024 The Author(s)Objective: The first COVID-19 pandemic wave was a period of reduced surgical activity and redistribution of resources to only those with late stage or critical presentations. This Vascular and Endovascular Research Network COVID-19 Vascular Service (COVER) study aimed to describe the six-month outcomes of patients who underwent open surgery and or endovascular interventions for major vascular conditions during this period. Methods: In this international, multicentre, prospective, observational study, centres recruited consecutive patients undergoing vascular procedures over a 12-week period. The study opened in March 2020 and closed to recruitment in August 2020. Patient demographics, procedure details, and post-operative outcomes were collected on a secure online database. The reported outcomes at 30 days and six months were post-operative complications, re-interventions, and all cause in-hospital mortality rate. Multivariable logistic regression was used to assess factors associated with six-month mortality rate. Results: Data were collected on 3 150 vascular procedures, including 1 380 lower limb revascularisations, 609 amputations, 403 aortic, 289 carotid, and 469 other vascular interventions. The median age was 68 years (interquartile range 59, 76), 73.5% were men, and 1.7% had confirmed COVID-19 disease. The cumulative all cause in-hospital, 30-day, and six-month mortality rates were 9.1%, 10.4%, and 12.8%, respectively. The six-month mortality rate was 32.1% (95% CI 24.2–40.8%) in patients with confirmed COVID-19 compared with 12.0% (95% CI 10.8–13.2%) in those without. After adjustment, confirmed COVID-19 was associated with a three times higher odds of six-month death (adjusted OR 3.25, 95% CI 2.18–4.83). Increasing ASA grade (3–5 vs. 1–2), frailty scores 4–9, diabetes mellitus, and urgent and or immediate procedures were also independently associated with increased odds of death by six months, while statin use had a protective effect. Conclusion: During the first wave of the pandemic, the six-month mortality rate after vascular and endovascular procedures was higher compared with historic pre-pandemic studies and associated with COVID-19 disease