Multimodal Optimization with the Local Optimum Ranking 2 Algorithm

In optimization tasks, it is interesting to achieve a set of efficient solutions instead of one single output, in the case the best solution is not suitable. Many niching methods offer a diversified response, yet some important problems are common: (1) The most interesting solutions of each local optimum are not identified. Thus, the output is the overall population of solutions, which increases the work of the designer in verifying which solution is the most interesting. (2) Existing niching algorithms tend to distribute the solutions on the most promising regions, over-populating some local optima and sub-populating others, which leads to poor optimization.To solve these challenges, a novel niching method is presented, named local optimum ranking 2 (LOR2). This sorting methodology favors the exploration of a defined number of local optima and ranks each local population by objective value within each local optimum. Thus, is performed a multi-focus exploration, with an equalized number of solutions on each local optimum, while identifying which solutions are the local apices. To exemplify its application, the LOR2 algorithm is applied in the design optimization of a metallic cantilever beam. It achieves a set of efficient and diverse design configurations, offering both performance and diversity for structural design challenges.In addition, a second experiment describes how the algorithm can be applied to segment the domain of any function, into a mesh of similar sized or custom-sized elements. Thus, it can significantly simplify metamodels and reduce their computation time.

Multimodal Optimization with the Local Optimum Ranking 2 Algorithm

In optimization tasks, it is interesting to achieve a set of efficient solutions instead of one single output, in the case the best solution is not suitable. Many niching methods offer a diversified response, yet some important problems are common: (1) The most interesting solutions of each local optimum are not identified. Thus, the output is the overall population of solutions, which increases the work of the designer in verifying which solution is the most interesting. (2) Existing niching algorithms tend to distribute the solutions on the most promising regions, over-populating some local optima and sub-populating others, which leads to poor optimization.To solve these challenges, a novel niching method is presented, named local optimum ranking 2 (LOR2). This sorting methodology favors the exploration of a defined number of local optima and ranks each local population by objective value within each local optimum. Thus, is performed a multi-focus exploration, with an equalized number of solutions on each local optimum, while identifying which solutions are the local apices. To exemplify its application, the LOR2 algorithm is applied in the design optimization of a metallic cantilever beam. It achieves a set of efficient and diverse design configurations, offering both performance and diversity for structural design challenges.In addition, a second experiment describes how the algorithm can be applied to segment the domain of any function, into a mesh of similar sized or custom-sized elements. Thus, it can significantly simplify metamodels and reduce their computation time.

Effectiveness of the COVID-19 Contact-Confirming Application (COCOA) Based on Multi-Agent Simulation

As of Aug. 2020, coronavirus disease 2019 (COVID-19) is still spreading in the world. In Japan, the Ministry of Health, Labour and Welfare developed “COVID-19 Contact-Confirming Application (COCOA),” which was released on June 19, 2020. By utilizing COCOA, users can know whether or not they had contact with infected persons. If those who had contact with infected individuals keep staying at home, they may not infect those outside. However, effectiveness decreasing the number of infected individuals depending on the app’s various usage parameters is not clear. If it is clear, we could set the objective value of the app’s usage parameters (e.g., the usage rate of the total populations) and call for installation of the app. Therefore, we develop a multi-agent simulator that can express COVID-19 spreading and usage of the apps, such as COCOA. In this study, we describe the simulator and the effectiveness of the app in various scenarios. The result obtained in this study supports those of previously conducted studies.

Multi-objective dynamic programming with limited precision

This paper addresses the problem of approximating the set of all solutions for Multi-objective Markov Decision Processes. We show that in the vast majority of interesting cases, the number of solutions is exponential or even infinite. In order to overcome this difficulty we propose to approximate the set of all solutions by means of a limited precision approach based on White’s multi-objective value-iteration dynamic programming algorithm. We prove that the number of calculated solutions is tractable and show experimentally that the solutions obtained are a good approximation of the true Pareto front.

Emotions Under Trauma

While emotions can play positive, contributory roles in our cognition and our lives, they frequently have the opposite effect. Michael Brady’s otherwise excellent introduction to the topic of emotion is unbalanced because he does not attend to harms emotions cause. The basic problem is that emotions have a normative aspect: they can be justified or unjustified and Brady does not attend to this. An example of this is Brady’s discussion of curiosity as the emotional motivation for knowledge. More importantly, while emotions can and sometimes do reveal to us what we value, it is far less frequent that emotions reveal objective value.

Beyond the Basics of Emotions

While emotions can play positive, contributory roles in our cognition and our lives, they frequently have the opposite effect. Michael Brady’s otherwise excellent introduction to the topic of emotion is unbalanced because he does not attend to harms emotions cause. The basic problem is that emotions have a normative aspect: they can be justified or unjustified and Brady does not attend to this. An example of this is Brady’s discussion of curiosity as the emotional motivation for knowledge. More importantly, while emotions can and sometimes do reveal to us what we value, it is far less frequent that emotions reveal objective value.

Personalizing the control law of an upper-limb exoskeleton using EMG signal

Implementing an intuitive control law for an upperlimb exoskeleton dedicated to force augmentation is a challenging issue in the field of human-robot collaboration. The goal of this study is to adapt an EMG-based control system to a user based on individual characteristics. To this aim, a method has been designed to tune the parameters of control using objective criteria, improving user's feedback. The user's response time is used as an objective value to adapt the gain of the controller. The proposed approach was tested on 10 participants during a lifting task. Two different conditions have been used to control the exoskeleton: with a generic gain and with a personalized gain. EMG signals was captured on five muscles to evaluate the efficiency of the conditions and the user's adaptation. Results showed a statistically significant reduction of mean muscle activity of the deltoid between the beginning and the end of each situation (28.6%, standard deviation (SD) 13.5% to 17.2%, SD 7.3%, of Relative Maximal Contraction for the generic gain and from 24.9%, SD 8.5%, to 18%, SD 6.8%, of Relative Maximal Contraction for the personalized gain). When focusing on the first assisted movements, the personalized gain induced a mean activity of the deltoid significantly lower (29%, SD 8.0%, of Relative Maximal Contraction and 37.4%, SD 9.5%, of Relative Maximal Contraction, respectively). Subjective evaluation showed that the system with a personalized gain was perceived as more intuitive, and required less concentration when compared to the system with a generic gain.

Impact of COVID-19 Pandemic on Anesthesia and Critical Care Residents in Spain

Background: The pandemic caused by coronavirus disease 2019 (COVID-19) has substantially changed the activity in Spanish healthcare centers. Residents who face pandemics are vulnerable physicians with different knowledge and experience. Objectives: This study aimed to determine the impact of COVID-19 pandemic on the Anesthesia and Critical Care residents and to establish its formative and personal consequences. Methods: A 35-question digital survey was developed, and was distributed among Anesthesia and Critical Care residents in Spain. The quantitative variable "Objective Formative Impact Score" (PIOF) was defined, being proportional to the impact on formative routines. Results: Several parameters were associated to a higher formative impact, such as the exposition to patients with COVID-19 (P = 0,020), an increase in the autonomy (P = 0,001), fear to contagion due to lack of protective equipment (P = 0,003), working in higher incidence areas (P < 0,001), being assigned to COVID-19 critical care units (P < 0,001), or to other departments different from Anesthesia and Critical Care. Residents experienced feelings of loneliness from the social distancing or ethical conflicts when working in suboptimal conditions. Conclusions: COVID-19 pandemic has had a major impact on Anesthesia and Critical Care residents both personally and formatively. The designed parameter PIOF brings an objective value about residents' formation.

An Evaluation of First-Come, First-Served Scheduling in a Geometrically-Constrained Wet Bulk Terminal

In 2022, a new sea lock at IJmuiden is expected to open, permitting an increase in marine traffic of larger ships from the sea to the port. In the interest of facilitating operations, we evaluate the impact of the current first-come, first-served (FCFS) admittance policy in the context of berth allocation for a wet bulk terminal in the port. Four model types are constructed: optimal FCFS; no FCFS with fixed arrival times; 48-h arrival time relaxation; and complete arrival time relaxation. Comparison of the model types is done by means of a rolling time window: of each day within the time frame, a schedule was created for the following 2 weeks, after which the objective value was calculated. When comparing the average of all objective values, it was found that the optimal FCFS model already shows an improvement compared to the historical situation. Between the FCFS and the no FCFS model, there are no considerable differences, because the vessels are constrained to be scheduled on/after their arrival time at the port. When relaxation is allowed, a considerable efficiency gain is possible, especially if larger ships arrive at the port.