Incorrect Performance Research Articles

You better listen to yourself: studying metacognitive efficiency in emotion recognition by voice

PurposeMetacognition, or the ability to monitor the performance of oneself, is known for its fundamental importance for human behavior adjustments. However, studies of metacognition in social behaviors focused on emotion recognition are relatively scarce. In the current study, we aimed to examine the effectiveness of metacognition, measured by self-rated confidence in voice emotion recognition tasks within healthy individuals.MethodsWe collected 180 audio-recorded lexical sentences portraying discrete emotions: anger, happiness, sadness, fear, surprise, and neutrality expressions. Upon listening to voice stimuli, participants (N = 100; 50 females, 50 males) completed the perception task of recognition of emotion. After each trial, a confidence rating (CR) was assigned.ResultsA series of one-tailed t-tests showed that the differences in mean CRs assigned to correct and incorrect performances were significant for all emotions and neutral expression.ConclusionsOur preliminary results demonstrate efficiency in metacognition of emotion recognition by voice. Theoretically, our results support the difference between accuracy in metacognition, measured by CR, and efficiency in metacognition, as it specified the CR between correct and incorrect performance. To gain better insights into practical issues, further studies are needed to examine whether and what are the differences between accuracy and efficiency in metacognition, as part of social communication.

Nurses Knowledge and Performance Toward Physical Restraint at Critical Care Units

Abstract:
 Objective: The study was done to evaluate nurses’ knowledge and practices toward physical restraint at critical care unit
 Methodology: Fifty nurses, who were selected by a non-probability (convenient) sampling method, participated in this descriptive study. The instrument of the study was knowledge parts of the questionnaire were initially developed in the U.S.A for nursing homes; in 2006 they were adopted for all hospital units by the original developers. The knowledge section of the questionnaire consisted of 20 items, which were used to measure knowledge of nurses towards the definition, indications and contraindications, proper application and legal and ethical considerations of physical restraint use. A three- point ordinal scale (Agree, Uncertain and Disagree) was applied to determine nurses’ responses to the items; it contained negative and positive sentences. Positive items, if answered with “agree,” were considered correct; if answered with “disagree,” items were considered incorrect. To evaluate the nurse's practices with respect to physical restraint, the researcher observes and checks for correct or incorrect performance. The practices checklist for nurses is composed of (94) items divided into six content domains.
 Results: The result of this research showed that 90% of nurses had low knowledge about physical restraint, and 80 % of the participants had unsatisfactory performance.
 Recommendation: The study recommended development of local policies for physical restraint use including detailed descriptions of conditions requiring its use is mandatory.
 Key words- Knowledge, Performance, Physical Restraint, Critical Care Units

Analysis of the results of medical care provided by emergency medical teams for injuries in the neck area

The analysis of the results of medical care at various stages of treatment of 86 people who received stab wounds in the neck area was performed. The male wounded predominated, of which there were 65 (75.6%) people, there were 21 (24.4%) women. The study shows that errors in the provision of medical care in the case of a neck injury occur in 31.4% of cases, while such errors were noted in 8.1% of cases when medical care was provided by medical teams of emergency medical care, whereas in the provision of medical care by paramedic teams of emergency medical care in 22.1% of cases. Basically, the errors were associated with incorrect performance of temporary hemostasis and underestimation of the condition of the wounded, as a result, the wounded from this localization developed or had a high risk of developing various compli[1]cations, including shock. This could not but affect the course of the nearest postoperative period with such injuries. Based on the analysis, it was found that in the group of wounded who received medical care by medical teams of emergency medical care, there was a statistically significant decrease in complications and deaths compared to the group where such assistance was provided by paramedic teams of emergency med[1]ical care. From this it can be concluded that neck injuries are the most severe injuries, higher qualifications are required to provide assistance with such injuries, while preference should be given to medical teams of emergency medical care.

Factors associated with hand washing effectiveness: an institution-based observational study

BackgroundFew studies have investigated how the effectiveness of hand washing in removing hand contaminants is influenced by the performance and duration of each step involved. We conducted an observational study by recruiting participants from a university campus, with the aim to comprehensively evaluate how performance, duration and demographic factors influence hand washing effectiveness.MethodsA total of 744 videos were collected from 664 participants in July-October 2022 and independently evaluated by two infection control experts through labelling videos for correct and incorrect performance of each step. The individual hand washing effectiveness was determined by quantifying the percentage of residual fluorescent gel on the dorsum and palm areas of each participant’s hands. A logistic regression analysis was conducted to identify factors that were significantly associated with better hand washing effectiveness. An exposure-response relationship was constructed to identify optimal durations for each step. Approximately 2300 hand images were processed using advanced normalization algorithms and overlaid to visualize the areas with more fluorescence residuals after hand washing.ResultsStep 3 (rub between fingers) was the most frequently omitted step and step 4 (rub the dorsum of fingers) was the most frequently incorrectly performed step. After adjustment for covariates, sex, performance of step 4 and step 7 (rub wrists), rubbing hands during rinsing, and rinsing time were significantly associated with hand washing effectiveness. The optimal overall hand washing time was 31 s from step 1 to step 7, and 28 s from step 1 to step 6, with each step ideally lasting 4–5 s, except step 3. The palms of both hands had less fluorescence residuals than the dorsums. The areas where residuals most likely appeared were wrists, followed by finger tips, finger webs and thumbs.ConclusionsPerformance and duration of some hand washing steps, sex and rinsing time were associated with hand washing effectiveness. The optimal duration might be applied to all seven steps to achieve the best decontamination results. Further studies are needed to refine hand hygiene standards and enhance compliance.

Improve Productivity and Quality Using Lean Six Sigma: A Case Study

Continuous improvement activities are widely deployed, applying the DMAIC cycle in the Lean Six Sigma method combined with 5s activities and industrial engineering tools such as Man-Machine chart statistics tools in DFSS (Design For Six Sigma). The results of the improvement activity must be approved and operated by the machine operator, measuring the loyalty of operators, users and system maintainers after kaizen against satisfaction criteria, technicality, usefulness and convenience are needed. This study proposes a model that com- bines the PLS - SEM method to measure user loyalty and implement a training program for users on incorrect performance results to improve CDIO stan- dards. The result is a reduction of workers at the processing line from 4 people on two shifts to 2 people, and the amount of money brought in is 10,224 USD per year. Defect of negative outside diameter decreased from 31.2% to 4.5% based on the amount of waste reduction of USD 980 per year. In terms of productivity increased from 15 units per hour per person to 30 units.

Reinforced practical Byzantine fault tolerance consensus protocol for cyber physical systems

Cyber–physical systems (CPS) are becoming an essential component of modern life. CPS services enable information to be exchanged between physical devices and virtual systems. The increasing malicious activities causing confidential data leakage and incorrect performance of devices are posing challenges for protection against cyber threats. Therefore, development of effective solutions that can protect both CPS data and data exchange networks are extremely urgent. This study makes some improvements on Practical Byzantine Fault Tolerance (PBFT), and provides a critical analysis of the feasibility of using blockchain technology to protect constrained CPS data. It also justifies the choice of the improved PBFT for implementation on such devices and simulates the main distributed ledger scenarios. The improved PBFT works as follows: first, the client broadcasts the signed transaction data to the entire network, rather than just the master node, followed by a hash value comparison verification process; second, select the master node based on the longest chain principle, and punish the malicious node via the “blacklist” mechanism; third, add the data synchronization and verification process, as well as dynamically entering and leaving nodes via state transitions. Ultimately, the PBFT commit phase is eliminated, resulting in a two-stage process. In comparison to the original PBFT protocol, the Reinforced Practical Byzantine Fault Tolerance (RPBFT) protocol may substantially enhance system throughput and minimize consensus communication time, thereby improving overall system efficiency while guaranteeing security.

Finite Element Analysis of the Influence of Chamfer Hub Geometry on the Stress Concentrations of Shrink Fits

The theoretical expressions commonly used in the design of interference fits do not take into account the huge stress concentrations located at the edges of the hub. This underestimation of the real stress state can induce the incorrect performance of the shaft–hub assembly. Among the different methods to address this problem is the use of chamfer hubs, which are used for reducing such stress concentrations. In this paper, an analysis, performed via finite element method, of the influence of the geometric parameters of a shrink fit with chamfer hubs was carried out with the aim of determining the optimal dimensions for the design of this type of mechanical assembly. To achieve this goal, different chamfer hub geometries were considered: (i) full–chamfer hubs defined by the chamfer angle and (ii) partial–chamfer hubs defined by the chamfer angle and the chamfer height. According to the obtained results, stress concentrations can be reduced by using a full–chamfer hub with chamfer angles within the range 13°–15° depending on the hub thickness. In addition, similar results can be obtained by using partial–chamfer hubs with a chamfer height of half of the hub thickness and chamfer angles within the range 13°–15°. By using these design recommendations, the theoretical equations can be used without underestimating the real stress state.

The association between Chinese eye exercises and myopia in children and adolescents: A systematic review and meta-analysis.

This study aims to summarize the relevant evidence on the association between eye exercises and myopia in children and adolescents in China. The meta-analysis pooled the results of 12 studies, with a total of 134,201 participants. Another five studies (no OR for myopia as an outcome and meeting inclusion criteria) were reported in the systematic review. We searched PubMed, Web of Science, CNKI, Wan Fang, and reference lists of retrieved studies. Association estimates were pooled using random-effects meta-analyses. Odds ratios (ORs) and 95% confidence intervals (CIs) for eye exercises and myopia were pooled from a meta-analysis. After standardizing the reference values, a pooled OR of the univariate analysis showed a 24% reduction in myopia in children and adolescents who performed eye exercises (OR = 0.76; 95% CI: 0.62-0.89). After adjusting the covariate, a pooled OR of multiple logistic analysis for myopia (OR = 0.87; 95% CI: 0.72-1.02) showed that there is no significance between eye exercises and myopia. However, in subgroup studies of the multivariate analysis, the large sample (OR = 0.84; 95% CI: 0.74-0.94) and Chinese database (OR = 0.80; 95% CI: 0.67-0.93) subgroup showed modest protective effects. In addition, five studies in the systematic review also evaluated the risk of myopia events, and Chinese eye exercises had a modest protective effect on myopic control, but the incorrect performance of and attitude toward eye exercises posed negative effects on their eyesight health. Chinese eye exercises have a modest protective effect on myopic control, but considering that the incorrect performance of and attitude toward eye exercises have a significant influence on the effect of eye exercises, the effect of eye exercises may not be enough to prevent the progress of myopia in the long term, and more standardized eye exercises need to be conducted.

Contributions of age and clinical depression to metacognitive performance

One aspect of metacognition is the ability to judge the accuracy of our own performance, even in the absence of external feedback, which is often measured using confidence ratings.Past research suggests that confidence is lower in Major Depressive Disorder (MDD). Less is known about the ability of MDD patients to discriminate correct from incorrect performance (metacognitive efficiency). The metacognitive performance of aged MDD patients (62-89y) was compared to an age-matched control group. A younger control group (21-28y) was included to also explore the relationshipbetweenageandmetacognitive performance.We found no difference in confidence bias nor metacognitive efficiency between MDD patients and age-matched controls.We found age-related differences in metacognition:normal aging was associated with higher confidencebut lower metacognitive efficiency. The overconfidence was specifically driven by overconfidence in incorrect trials. Our results point to the importance ofage while investigating the relation between MDD and metacognitive performance.

Effectiveness of an interventional program on nurses practices toward enteral nutritional support for unconscious patient at critical care unite in Imam al-Hussein medical city in Holy Karbala

Background: , nurses lack the expertise and awareness of enteral nutrition, indicating the necessity of educating them on the nutitonal support . Enhancing the intensive care nurses' knowledge about nutrition may lead to improved nursing practices. Objectives: to determine the effectiveness of the interventional program on nurses practices toward enteral nutritional support for unconscious patient. Methods: A quasi-experimental was conducted at the Critical Care Unit in Imam AL-Hussein Medical City in Holy Karbala . A non-probability "purposive sample" of (60) nurses who are working at critical care unit . the sample divided into two groups, control group consist of (30) nurses and study group consist of (30) nurses exposed to the nursing educational program. Data were collected by the researcher observed and checked for correct and incorrect performance. The nurses' Practices check list was composed of (48 ) items. Results: The study's findings indicate that the study group's practices of enteral nutrition support for unconscious patients is greater to that of the control group at the post-test, as compared to the control group's knowledge, so the interventional program was effective in increasing nurses' practices. Conclusion: The nurse's practice's toward nutrition support for unconscious patients is inadequate at pre-test.

Effectiveness of an interventional program on nurses practices toward enteral nutritional support for unconscious patient at critical care unite in Imam Al-Hussein Medical City in Holy Karbala

Background: nurses lack the expertise and awareness of enteral nutrition, indicating the necessity of educating them on the nutitonal support. Enhancing the intensive care nurses' knowledge about nutrition may lead to improved nursing practices. Objectives: to determine the effectiveness of the interventional program on nurses practices toward enteral nutritional support for unconscious patient. Methods: A quasi-experimental was conducted at the Critical Care Unit in Imam AL-Hussein Medical City in Holy Karbala. A non-probability "purposive sample" of (60) nurses who are working at critical care unit. The sample divided into two groups, control group consist of (30) nurses and study group consist of (30) nurses exposed to the nursing educational program. Data were collected by the researcher observed and checked for correct and incorrect performance. The nurses' Practices check list was composed of (48) items. Results: The study's findings indicate that the study group's practices of enteral nutrition support for unconscious patients is greater to that of the control group at the post-test, as compared to the control group's knowledge, so the interventional program was effective in increasing nurses' practices. Conclusion: The nurse's practice's toward nutrition support for unconscious patients is inadequate at pre test.

The Nurse’s Role in Educating Pediatric Patients on Correct Inhaler Technique: An Interventional Study

The prevalence of pediatric respiratory diseases in Spain is 23%. Inhalation is the preferred route of administration but there are frequent errors in the performance of the inhalation technique leading a poor control of the disease. The aim of this research was to detect errors in the execution of the inhalation technique at a Pediatric Pulmonology Unit in a hospital of Aragón (Spain). In order to improve the administration of inhaled medication, an educational intervention for 1 year by nursing was conducted. This interventional study, including children aged 1 to 15 years with an inhalation therapy and who attended the Pediatric Pulmonology Unit, was conducted between September 2017 and September 2018. Logistic Regression models were conducted in SPSS. This study involved 393 children (61.1% boys). Before the intervention, 39.4% achieved a correct inhalation technique increasing up to 62.1% after the intervention. Those who had their first visit to the Unit, young children and girls had a higher risk of incorrect performance than those with subsequent visits, older children, and boys, respectively. The most common errors in the inhalation technique were not performing adequate apnoea after inhaling and not rinsing the mouth at the end of the procedure. The education given by nurses to pediatric patients improved the inhalation technique, achieving better control of the disease and use of the health system.

Persistent neuronal firing in the medial temporal lobe supports performance and workload of visual working memory in humans

The involvement of the medial temporal lobe (MTL) in working memory is controversially discussed. Recent findings suggest that persistent neural firing in the hippocampus during maintenance in verbal working memory is associated with workload. Here, we recorded single neuron firing in 13 epilepsy patients (7 male) while they performed a visual working memory task. The number of colored squares in the stimulus set determined the workload of the trial. Performance was almost perfect for low workload (1 and 2 squares) and dropped at high workload (4 and 6 squares), suggesting that high workload exceeded working memory capacity. We identified maintenance neurons in MTL neurons that showed persistent firing during the maintenance period. More maintenance neurons were found in the hippocampus for trials with correct compared to incorrect performance. Maintenance neurons increased and decreased firing in the hippocampus and increased firing in the entorhinal cortex for high compared to low workload. Population firing predicted workload particularly during the maintenance period. Prediction accuracy of workload based on single-trial activity during maintenance was strongest for neurons in the entorhinal cortex and hippocampus. The data suggest that persistent neural firing in the MTL reflects a domain-general process of maintenance supporting performance and workload of multiple items in working memory below and beyond working memory capacity. Persistent neural firing during maintenance in the entorhinal cortex may be associated with its preference to process visual-spatial arrays.

An Attempt at Describing Learning Curves for a Complex Sub-Task in Reading Acquisition

Learning curves are a well-known phenomenon in learning and describe the oscillation between correct and incorrect performance that precedes mastery. It demonstrates that making mistakes is part of the learning process. It is equally clear that these learning curves are highly individual and therefore pose a challenge in their description and direct comparison. With the ability to collect large amounts of data through learning games with adaptively generated content, it is now possible to take a novel look at this process. Literacy games were deployed in a school setting for the iRead EU Horizon 2020 Project. The Navigo app delivered a complex task of practising to distinguish vowel length in bi-syllabic words in German to pupils in the disguise of a game. Pupils' engagement with the game resulted in the largest longitudinal corpus that has ever been collected for this sort of task from 251 pupils in German elementary schools. The resulting data exhibits learning curves as trajectories, depicting response time and correctness across several weeks for each pupil’s playing sessions. The work presented here attempts to (a) model and parameterise these curves, (b) automate their classification into common forms across a larger population, and (c) detect mastery. In doing so, we propose a method of learning curve representation and interpretation and apply it to the data. A describable pattern of cognitive processing seems to be observable and common to all curves that may allow a prediction of mastery and ability for skill transfer to other environments for a subset of the players. As a result, we were able to describe five general types of common progressions. These findings are in part supported by additional data from pre- and post-tests in the form of paper-and-pencil activities. The work presented here should serve to demonstrate the importance of using large scale input data for training literacy skills rather than a few examples as is the norm in static schoolbooks.

Uncovering and Correcting Shortcut Learning in Machine Learning Models for Skin Cancer Diagnosis.

Machine learning models have been successfully applied for analysis of skin images. However, due to the black box nature of such deep learning models, it is difficult to understand their underlying reasoning. This prevents a human from validating whether the model is right for the right reasons. Spurious correlations and other biases in data can cause a model to base its predictions on such artefacts rather than on the true relevant information. These learned shortcuts can in turn cause incorrect performance estimates and can result in unexpected outcomes when the model is applied in clinical practice. This study presents a method to detect and quantify this shortcut learning in trained classifiers for skin cancer diagnosis, since it is known that dermoscopy images can contain artefacts. Specifically, we train a standard VGG16-based skin cancer classifier on the public ISIC dataset, for which colour calibration charts (elliptical, coloured patches) occur only in benign images and not in malignant ones. Our methodology artificially inserts those patches and uses inpainting to automatically remove patches from images to assess the changes in predictions. We find that our standard classifier partly bases its predictions of benign images on the presence of such a coloured patch. More importantly, by artificially inserting coloured patches into malignant images, we show that shortcut learning results in a significant increase in misdiagnoses, making the classifier unreliable when used in clinical practice. With our results, we, therefore, want to increase awareness of the risks of using black box machine learning models trained on potentially biased datasets. Finally, we present a model-agnostic method to neutralise shortcut learning by removing the bias in the training dataset by exchanging coloured patches with benign skin tissue using image inpainting and re-training the classifier on this de-biased dataset.

The Relationship Between Confidence and Conformity in a Non-routine Counting Task With Young Children: Dedicated to the Memory of Purificación Rodríguez.

Counting is a complex cognitive process that is paramount to arithmetical development at school. The improvement of counting skills of children depends on their understanding of the logical and conventional rules involved. While the logical rules are mandatory and related to one-to-one correspondence, stable order, and cardinal principles, conventional rules are optional and associated with social customs. This study contributes to unravel the conceptual understanding of counting rules of children. It explores, with a developmental approach, the performance of children on non-routine counting detection tasks, their confidence in their answers (metacognitive monitoring skills), and their ability to change a wrong answer by deferring to the opinion of a unanimous majority who justified or did not justify their claims. Hundred and forty nine children aged from 5 to 8 years were randomized to one of the experimental conditions of the testimony of teachers: with (n = 74) or without justification (n = 75). Participants judged the correctness of different types of counting procedures presented by a computerized detection task, such as (a) pseudoerrors that are correct counts where conventional rules are violated (e.g., first counting six footballs, followed by other six basketballs that were interspersed along the row), and (b) compensation errors that are incorrect counts where logical rules were broken twice (e.g., skipping the third element of the row and then labeling the sixth element with two number words, 5 and 6). Afterwards, children rated their confidence in their detection answer with a 5-point scale. Subsequently, they listened to the testimony of the teachers and showed either conformity or non-conformity. The participants considered both compensation errors and pseudoerrors as incorrect counts in the detection task. The analysis of the confidence of children in their responses suggested that they were not sensitive to their incorrect performance. Finally, children tended to conform more often after hearing a justification of the testimony than after hearing only the testimonies of the teachers. It can be concluded that the age range of the evaluated children failed to recognize the optional nature of conventional counting rules and were unaware of their misconceptions. Nevertheless, the reasoned justifications of the testimony, offered by a unanimous majority, promoted considerable improvement in the tendency of the children to revise those misconceptions.

An analysis of verbal fluency task performance profiles in patients with vascular brain pathology

Aim: Considering the data on the important role of verbal fluency tasks in neuropsychological diagnosis and the models of hemispherically specialised modulation of processes essential for different types of verbal fluency, we made an attempt to identify differences in correct and incorrect performance of 5 verbal fluency tasks between patients with vascular cerebral pathology, including hypertension, and healthy individuals. We also analysed task performance profiles within the groups. Materials and methods: The study included healthy volunteers (n = 36), hypertensive individuals (n = 33), and patients after left (n = 15) or right hemisphere stroke (n = 30) – 114 subjects in total. We used the Frenchay Aphasia Screening Test (FAST) to exclude patients with significant language difficulties/aphasia. We used 5 verbal fluency tasks: semantic (Animals), phonemic (“k”), verb fluency and two emotional tasks: Joy and Fear. We used general linear models for repeated measures for the analysis of correctly and incorrectly performed tasks. Results: The profiles of correct responses for all 5 tasks were similar in all groups, with quantitative intergroup differences. The highest number of correct responses appeared in the semantic, phonemic and verb fluency tasks, whereas the lowest number in the emotional tasks. Hypertensive individuals scored statistically insignificantly lower than healthy individuals, whereas patients after right/left hemisphere stroke scored significantly lower compared to both these groups. Despite a large number of errors, healthy individuals had the highest scores. Patients after right hemisphere stroke showed little differentiation in the number of correct responses in subsequent tasks. There were no intergroup differences in the level of performance of emotional tasks with different valences (positive and negative). Healthy and hypertensive individuals were characterised by a distinct heterogeneity of correct and incorrect responses in various tasks. Patients with brain pathology, regardless of its lateralisation, performed these tasks at a similar level, with left hemisphere damage resulting in the highest number of errors, mainly in semantic and phonemic tasks, and with right hemisphere pathology associated with errors in all types of tasks. The difficulties in patients with left hemisphere damage may result from weaker phonological and lexical processes, including access to semantic features of a word, while the low scores of patients with right hemisphere damage may be a consequence of impaired attention and executive processes. Conclusions: Patients with vascular pathology of the brain hemispheres achieved significantly lower scores in all types of fluency, while hypertensive individuals scored insignificantly lower than healthy subjects. This means that the method can be useful in differentiating between healthy individuals and patients with central nervous system damage, as well as those at risk. Future research should focus on a detailed analysis of the types of errors made by patients with hemispheric damage in various types of verbal fluency tasks. An analysis of the location of the pathology in the anterior-posterior dimension of each hemisphere could reveal specific features of verbal fluency.

Outlier Detection Transilience-Probabilistic Model for Wind Tunnels Based on Sensor Data.

Anomaly Detection research is focused on the development and application of methods that allow for the identification of data that are different enough—compared with the rest of the data set that is being analyzed—and considered anomalies (or, as they are more commonly called, outliers). These values mainly originate from two sources: they may be errors introduced during the collection or handling of the data, or they can be correct, but very different from the rest of the values. It is essential to correctly identify each type as, in the first case, they must be removed from the data set but, in the second case, they must be carefully analyzed and taken into account. The correct selection and use of the model to be applied to a specific problem is fundamental for the success of the anomaly detection study and, in many cases, the use of only one model cannot provide sufficient results, which can be only reached by using a mixture model resulting from the integration of existing and/or ad hoc-developed models. This is the kind of model that is developed and applied to solve the problem presented in this paper. This study deals with the definition and application of an anomaly detection model that combines statistical models and a new method defined by the authors, the Local Transilience Outlier Identification Method, in order to improve the identification of outliers in the sensor-obtained values of variables that affect the operations of wind tunnels. The correct detection of outliers for the variables involved in wind tunnel operations is very important for the industrial ventilation systems industry, especially for vertical wind tunnels, which are used as training facilities for indoor skydiving, as the incorrect performance of such devices may put human lives at risk. In consequence, the use of the presented model for outlier detection may have a high impact in this industrial sector. In this research work, a proof-of-concept is carried out using data from a real installation, in order to test the proposed anomaly analysis method and its application to control the correct performance of wind tunnels.

Enhancing Lattice-Based Motion Planning With Introspective Learning and Reasoning

Lattice-based motion planning is a hybrid planning method where a plan made up of discrete actions simultaneously is a physically feasible trajectory. The planning takes both discrete and continuous aspects into account, for example action pre-conditions and collision-free action-duration in the configuration space. Safe motion planing rely on well-calibrated safety-margins for collision checking. The trajectory tracking controller must further be able to reliably execute the motions within this safety margin for the execution to be safe. In this work we are concerned with introspective learning and reasoning about controller performance over time. Normal controller execution of the different actions is learned using reliable and uncertainty-aware machine learning techniques. By correcting for execution bias we manage to substantially reduce the safety margin of motion actions. Reasoning takes place to both verify that the learned models stays safe and to improve collision checking effectiveness in the motion planner by the use of more accurate execution predictions with a smaller safety margin. The presented approach allows for explicit awareness of controller performance under normal circumstances, and timely detection of incorrect performance in abnormal circumstances. Evaluation is made on the nonlinear dynamics of a quadcopter in 3D using simulation. Video: https://youtu.be/STmZduvSUMM

On Performance of PBFT Blockchain Consensus Algorithm for IoT-Applications With Constrained Devices

Cyber-physical systems and the Internet of things (IoT) are becoming an integral part of the digital society. The use of IoT services improves human life in many ways. Protection against cyber threats is an utmost important prospect of IoT devices operation. Malicious activities lead to confidential data leakage and incorrect performance of devices becomes critical. Therefore, development of effective solutions that can protect both IoT devices data and data exchange networks turns in to a real challenge. This study provides a critical analysis of the feasibility of using blockchain technology to protect constrained IoT devices data, justifies the choice of Practical Byzantine Fault Tolerance (PBFT) consensus algorithm for implementation on such devices, and simulates the main distributed ledger scenarios using PBFT. In this paper we investigate typical IoT network scenarios that can disrupt system performance. To ensure the adequacy of the models under study, we have analyzed the characteristics of real constrained IoT devices in terms of computing power and data rate. The simulation results demonstrate efficiency of the blockchain technology for constrained devices and make it possible to evaluate applicability limits of the chosen consensus algorithm.