Improved algorithm for minimum zone of roundness error evaluation using alternating exchange approach

Based on the computational geometry technique, an improved algorithm for minimum zone of roundness error evaluation using an alternating exchange method is presented. A minimum zone fitting function was created to enhance the roundness error evaluation. The function uses three candidate points to determine the initial solution: the expected centre, the mean circle radius, and the corresponding zone half-width. The best solution function is designed to use the initial solution as the input to determine the optimum solution for the minimum zone circle. The proposed algorithm was validated using data available in the literature. The roundness error evaluation comparison results demonstrate that the proposed method accurately detects both the centre error magnitude and minimum zone circle and overcomes the insufficiency of using selected colinear points for four selected points.

Pupillary dynamics of optimal effort

ABSTRACTWhile a substantial body of work has shown that cognitive effort is aversive and costly, a separate line of research on intrinsic motivation suggests that people spontaneously seek challenging tasks. According to one prominent account of intrinsic motivation, the Learning Progress Motivation theory, the preference for difficult tasks reflects the dynamic range that these tasks yield for minimization of performance accuracy prediction errors (Oudeyer, Kaplan & Hafner, 2007). Here we test this hypothesis, by asking whether greater engagement with intermediately difficult tasks, indexed by subjective ratings and objective pupil measurements, is a function of trial-wise changes in performance prediction error. In a novel paradigm, we determined each individual’s capacity for task performance and used difficulty levels that are too low, intermediately challenging or high for that individual. We demonstrated that intermediately challenging tasks resulted in greater liking and engagement scores compared with easy tasks. Task-evoked and baseline pupil size tracked objective task difficulty, where challenging tasks were associated with smaller baseline and greater phasic pupil responses than easy tasks. Most importantly, pupil responses were predicted by trial-to-trial changes in expected accuracy, performance prediction error magnitude and changes in prediction errors (learning progress), whereas smaller baseline pupil responses also predicted greater subjective engagement scores. Together, these results suggest that what is underlying the link between task engagement and intermediate tasks might be the dynamic range that these tasks yield for minimization of performance accuracy prediction errors.

Previously Unrecognized Source of Error in the Change in Maximum Total Point Motion to Determine Continuous Migration of Unstable Tibial Baseplates

In radiostereometric analysis (RSA), continuous migration denoted as ΔMTPM is the difference between maximum total point motion (MTPM) at 2 years relative to time zero and MTPM at 1 year relative to time zero. Continuous migration has been used to diagnose tibial baseplates as stable versus unstable when compared to a specified stability limit (i.e. value of ΔMTPM). If the same point experiences MTPM at 2 years and at 1 year (usually the case for marker-based RSA), then an implicit assumption is that the migration path between 2 years and 1 year is the same as the path between 1 year and time zero. This paper uses vector analysis to demonstrate a source of error in ΔMTPM not previously recognized and estimates the error magnitude based on the interplay of independent variables which affect the error. The two independent variables which affect the error are the angle between the two migration vectors (i.e., MTPM between time zero and 2 years and MTPM between time zero and 1 year) and the difference in magnitude of the two vectors. The relative error increased in an absolute sense as the angle between the vectors increased and decreased for larger differences in the magnitudes of the two vectors. For magnitude ratios ranging from 1.25 to 2, relative errors ranged from -21% to -3% at 10° and from -78% to -42% at 60°, respectively. Knowledge of these errors highlights a limitation in the use of ΔMTPM not previously recognized.

The effect of process design on refiner pulp quality control performance

In this study, the effect of process- and online analyser configuration on pulp quality control is explored. The following parameters were included: analyser sampling interval, time delay, measurement error magnitude, and latency chest residence time. Using different values of parameters in a process model, a range of configurations were constructed. For each configuration, the achievable control performance was evaluated using an optimization approach. PI controller settings were chosen based on minimization of the integrated absolute error (IAE) in pulp quality after an input step disturbance. The results show that reducing the sampling interval improves performance also when the interval is smaller than the chest residence time or the analyser delay. Moreover, reducing the chest residence time can reduce the IAE by up to 40 %. However, reducing the residence time to lower than 1/3 of the sampling interval does not improve performance. Further improvement is possible if the analyser delay is reduced. The compromise between reducing the IAE and avoiding creating variation by acting on measurement error has a strong influence on the results. In conclusion, pulp quality control performance can be improved significantly by making changes to the studied configuration parameters.

Does Head Orientation Influence 3D Facial Imaging? A Study on Accuracy and Precision of Stereophotogrammetric Acquisition

This study investigates the reliability and precision of anthropometric measurements collected from 3D images and acquired under different conditions of head rotation. Various sources of error were examined, and the equivalence between craniofacial data generated from alternative head positions was assessed. 3D captures of a mannequin head were obtained with a stereophotogrammetric system (Face Shape 3D MaxiLine). Image acquisition was performed with no rotations and with various pitch, roll, and yaw angulations. On 3D images, 14 linear distances were measured. Various indices were used to quantify error magnitude, among them the acquisition error, the mean and the maximum intra- and inter-operator measurement error, repeatability and reproducibility error, the standard deviation, and the standard error of errors. Two one-sided tests (TOST) were performed to assess the equivalence between measurements recorded in different head angulations. The maximum intra-operator error was very low (0.336 mm), closely followed by the acquisition error (0.496 mm). The maximum inter-operator error was 0.532 mm, and the highest degree of error was found in reproducibility (0.890 mm). Anthropometric measurements from alternative acquisition conditions resulted in significantly equivalent TOST, with the exception of Zygion (l)–Tragion (l) and Cheek (l)–Tragion (l) distances measured with pitch angulation compared to no rotation position. Face Shape 3D Maxiline has sufficient accuracy for orthodontic and surgical use. Precision was not altered by head orientation, making the acquisition simpler and not constrained to a critical precision as in 2D photographs.

Study of normal tissue dosimetric benefit using asymmetric margin-based biological fuzzy decision making: volumetric modulated arc therapy of prostate cancer

Aim: Radiation therapy has historically used margins for target volume to ensure dosimetric planning criteria. The size of margin for a given treatment site is still uncertain particularly for moving targets along with set-up variations leading to a fuzziness of target volume. In this study, we have estimated the dosimetric benefit of normal structures using biological-based optimal margins. The treatment margins are derived by knowledge-based fuzzy logic technique which is considering the radiotherapy uncertainties in treatment planning. Materials and methods: All treatment plans were performed using stepped increments of asymmetric margins to estimate prostate radiobiological indices such as tumour control probability (TCP) and normal tissue complication probability (NTCP). An absolute NTCP of 5% was considered to be the maximum acceptable value while TCP of 85% was considered to be the minimal acceptable limit for each volumetric modulated arc therapy (VMAT) plan of localised prostate cancer radiotherapy. Results were used to formulate rules and membership functions for Mamdani-type fuzzy inference system (FIS). In implementing the rules for the fuzzy system for ΔNTCP values above 10%, the PTV margin was not permitted to exceed 5 mm to avoid rectal complications due to margin selection. The new margins were applied in VMAT planning of prostate cancer for standard displacement errors. The dosimetric results of normal tissue predictors were estimated such as organ mean doses, rectum V60 (volume receiving 60 Gy), bladder V65 (volume receiving 65 Gy) and other clinically significant dose–volume indicators and compared with VMAT plans using current margin formulations. Results: Dosimetric results compared well to the results obtained by current techniques. Good agreement was obtained between proposed fuzzy model margins and currently used margins in lower error magnitude, but significant results were observed at higher error magnitude when organ toxicity concerned without compromising the target volumes. Findings: The new margins may be helpful to estimate possible outcomes of normal tissue complications and thus may improve complication free survival particularly when organ motion errors are inevitable, case by case.

Individual differences in frontal midline theta activity during visuomotor adaptation are related to execution noise

ABSTRACTFrontal midline EEG activity has been found to correlate with error magnitude during motor adaptation. We replicated a previous visuomotor adaptation experiment with very small perturbations, likely to invoke implicit adaptation, in a new group of 60 participants and combined it with EEG recordings. We used this data to explore 1) whether frontal midline activity will be evoked in the absence of awareness of the perturbation; 2) whether frontal midline activity is related to implicit adaptation; 3) whether individual differences in frontal midline activity are related to individual differences in motor learning. The results showed that frontal midline theta activity (FMΘ) is also present during small perturbations, does not drive between-trial error correction, and that the sensitivity of FMΘ to error magnitude was smaller for participants with greater execution noise. This relation between FMΘ-error-sensitivity and execution noise could be fully explained by looking at the relationship between FMΘ and error probability. This implies that frontal midline theta activity represents a surprise-like saliency signal, potentially driving awareness and cognitive control in situations with more salient errors.

Comparison of FPGA and Microcontroller Implementations of an Innovative Method for Error Magnitude Evaluation in Reed–Solomon Codes

Reed–Solomon (RS) codes are one of the most used solutions for error correction logic in data communications. RS decoders are composed of several blocks: among them, many efforts have been made to optimize the error magnitude evaluation module. This paper aims to assess the performance of an innovative algorithm introduced in the literature by Lu et al. under different systems configurations and hardware platforms. Several configurations of the encoded message chosen between those typically used in different applications have been designed to be run on an FPGA (field programmable gate array) device and an MCU (microcontroller unit). The performances have been evaluated in terms of resource usage and output delay for the FPGA and in terms of code execution time for the MCU. As a benchmark in the analysis, the well-established Forney’s method is exploited: it has been implemented in the same configurations and on the same hardware platforms for a proper comparison. The results show that the theoretical finding are fully confirmed only in the MCU implementation, while on FPGA, the choice of one method with respect to the other depends on the optimization feature (i.e., time or area) that has been decided as a preference in the specific application.