This paper proposes a novel method to cope with local measurement ambiguity problem in particle filtering. The ambiguity of the measurement has been attributed as a crucial cause of filter ...degradation and divergence. Given the observation that the ambiguous measurement update is contributed by not only the shape of the measurement model but also the prior distribution of the filter estimate, we adopt a solution to the out-of-sequence measurement problem on the framework of the particle filter with sequential importance resampling. Once an ambiguous measurement update is detected, the proposed method skips the measurement update at the time step and utilizes the measurement later when the particle distribution becomes adequate for the measurement update. This strategy provides a remedy to the ambiguity problem to obtain accurate current position estimate with lower covariance. Numerical simulation is presented to demonstrate effectiveness and performance of the proposed method. Compared to other methods, such as the standard particle filter, the auxiliary particle filter, the mixture particle filter, and the receding-horizon Kalman filter, the proposed method shows better performance in terms of root-mean-square error and estimated covariance.
Cooperation between pickers occurs when many picking assignments are needed to fill large orders. This study discusses two strategies for use in zone picking systems with pick-to-light (PTL) ...technology: along-a-line collaboration, i.e. , collaboration along a zone line, and across-a-line asynchronization, i.e. , relaxation of synchronization across a conveyor line. Queueing models, Continuous-timed Markov chains (CTMC), and simulations were used to determine if the strategies could improve throughput and cycle time. In simulations with industry cases and data, the along-a-line collaboration showed a 26.7~53.2% reduction, the across-a-line asynchronization showed an 8.2~21.0% reduction, and combining the strategies showed a 50.9~66.3% (on average 57.4%) reduction in cycle times compared to regular zone pickings without collaboration. An analytical comparison confirmed that using either strategy, or combining them, for zone picking systems with PTL technology can improve throughput and reduce work-in-process, particularly for large orders.
This paper focuses on maximizing the percent coverage and minimizing the revisit time for a small satellite constellation with limited coverage. A target area represented by a polygon defined by grid ...points is chosen instead of using a target point only. The constellation consists of nonsymmetric and circular Low Earth Orbit (LEO) satellites. A global optimization method, Genetic Algorithm (GA), is chosen due to its ability to locate a global optimum solution for nonlinear multiobjective problems. From six orbital elements, five elements (semimajor axis, inclination, argument of perigee, longitude of ascending node, and mean anomaly) are varied as optimization design variables. A multiobjective optimization study is conducted in this study with percent coverage and revisit time as the two main parameters to analyze the performance of the constellation. Some efforts are made to improve the objective function and to minimize the computational load. A semianalytical approach is implemented to speed up the guessing of initial orbital elements. To determine the best parametric operator combinations, the fitness value and the computational time from each study cases are compared.
► Effects of testing variables on SCC susceptibility of Al 2024-T351 in 3.5% NaCl solution were examined. ► Slow strain rate test (SSRT) method and a constant load test (CLT) method were utilised. ► ...Percent reductions in tensile elongation increased with decreasing strain rate. ► Anodic dissolution and hydrogen embrittlement played a role in the SCC process. ► CLT showed the similar SCC susceptibility obtained by SSRT.
In the present study, the effects of testing variables on stress corrosion cracking (SCC) susceptibility of Al 2024-T351 in 3.5% NaCl solution were examined using slow strain rate test (SSRT) method with controlled applied potentials and a constant load test (CLT) method. The SSRTs were conducted at various strain rates and applied potential, while the CLTs were performed with different exposure time, with different grain directions of ST (short-transverse) and L (longitudinal) to understand how the testing parameters affected on the SCC susceptibility of Al 2024-T351. The percent reductions in tensile elongation in an SCC-causing environment over those in air tended to express the SCC susceptibility of Al 2024-T351 most properly for both SSRT and CLT. The present fractographic examination suggested that both anodic dissolution and hydrogen embrittlement played a role in the SCC process of Al 2024-T351 in 3.5% NaCl solution at both anodic and cathodic applied potentials, and the contribution of each mechanism could vary with different testing variables. It was also found that the SCC susceptibility of Al 2024-T351 obtained from the CLT result could provide the similar SCC evaluation result obtained by SSRT with a proper selection of testing variables. The metallurgical aspect of SCC behaviour of Al 2024-T351 was also discussed based on the microstructural and fractographic examinations.
Recent studies have demonstrated the disassociation between the mu and beta rhythms of electroencephalogram (EEG) during motor imagery tasks. The proposed algorithm in this paper uses a fully ...data-driven multivariate empirical mode decomposition (MEMD) in order to obtain the mu and beta rhythms from the nonlinear EEG signals. Then, the strong uncorrelating transform complex common spatial patterns (SUTCCSP) algorithm is applied to the rhythms so that the complex data, constructed with the mu and beta rhythms, becomes uncorrelated and its pseudocovariance provides supplementary power difference information between the two rhythms. The extracted features using SUTCCSP that maximize the interclass variances are classified using various classification algorithms for the separation of the left- and right-hand motor imagery EEG acquired from the Physionet database. This paper shows that the supplementary information of the power difference between mu and beta rhythms obtained using SUTCCSP provides an important feature for the classification of the left- and right-hand motor imagery tasks. In addition, MEMD is proved to be a preferred preprocessing method for the nonlinear and nonstationary EEG signals compared to the conventional IIR filtering. Finally, the random forest classifier yielded a high performance for the classification of the motor imagery tasks.
We report printed flexible optoelectronic sensors composed of red organic light-emitting diodes (OLEDs) and organic photodiodes (OPDs) for detection of various biological signals in a ...photoplethysmograph (PPG) device. Fabricated flexible OLEDs achieved maximum luminance >1000 cd/m 2 at 9 V, with peak at 640 nm. Maximum flexible OPD photosensitivity for the poly(3-hexylthiophene-2, 5-diyl) and phenyl-C61-butyric acid methyl ester (PCBM) heterojunction is <inline-formula> <tex-math notation="LaTeX"> {2} \times {10}^{{2}} </tex-math></inline-formula> at 0 V and 1.76 at −1 V, irradiated with 1.2 mW/cm 2 at 660 nm. The diketopyrrolopyrrole thieno 3,2-bthiophene blended with PCBM OPDs with poly (3,4-ethylenedioxythiophene):polystyrene sulfonate anode showed photosensitivity = 84 at −1 V bias to almost <inline-formula> <tex-math notation="LaTeX">{6} \times {10}^{{4}} </tex-math></inline-formula> at 0 V accompanied by low dark current (<inline-formula> <tex-math notation="LaTeX">{9.5} \times {10}^{-{8}} </tex-math></inline-formula> A/cm 2 at −1 V). PPG signals were successfully detected using the developed flexible PPG sensor and the conventional driving circuit. Human studies were conducted to evaluate the flexible PPG sensor performance in practical applications. Subject drowsiness was estimated from heart rate variability, extracted from the PPG signals, using machine learning algorithms. The flexible PPG sensor achieved 79.2% accuracy and 72.1% area under the receiver (AUC) to predict drowsiness (60-s window), which are meaningful results compared with conventional PPG sensors (83.3% accuracy and 69% AUC). Drowsiness estimation experiments using two PPG signals showed that the flexible PPG sensor achieved similar or better performance compared to conventional PPG sensors.
Three different carbon-based counter electrodes are investigated in light of catalytic activities such as electrochemical frequencies and interface impedances. We fabricated carbon-based counter ...electrodes of dye-sensitized solar cells DSSCs using graphene, single-walled carbon nanotubes SWNTs, and graphene-SWNT composites by electrophoretic deposition method. We observed the optical and electrochemical properties of the carbon-based counter electrodes. The DSSC with the graphene-deposited counter electrode demonstrated the best conversion efficiency of 5.87% under AM 1.5 and 1 sun condition. It could be utilized for a low-cost and high-throughput process for DSSCs.
A “person under train” (PUT) incident is a suicidal action involving a person throwing themselves at a moving train. This may cause trauma, including post-traumatic stress disorder (PTSD), to ...railroad drivers. This study investigated the experiences of railroad drivers of a PUT incident. Data were obtained from two drivers through in-depth interviews and personal narratives regarding their PUT experience and personal lives after the incident. Expressing thoughts through writing was an effective intervention that provided insights into their experience. Thus, an educational program combining mental health management and PTSD treatment is recommended for workers who experience such trauma.
•Narrative exploration helps to alleviate post-traumatic stress disorder symptoms.•Governmental trauma management programs are need for traumatized engineers.•Railroad engineers who experience trauma are likely to ruminate on its memory.•Reinterpreting traumatic experiences can positively impact one's quality of life.•Immediate immersion is needed following trauma, with long-term follow-up.
The clinical application of cisplatin, one of the most effective chemotherapeutic agents used to treat various cancers, has been limited by the risk of adverse effects, notably nephrotoxicity. ...Despite intensive research for decades, there are no effective approaches for alleviating cisplatin nephrotoxicity. This study aimed to investigate the protective effects and potential mechanisms of a Gynostemma pentaphyllum leaves hydrodistillate (GPHD) and its major component, damulin B, against cisplatin-induced nephrotoxicity in vitro and in vivo. A hydro-distillation method can extract large amounts of components within a short period of time using non-toxic, environmentally friendly solvent. We found that the levels of AMP-activated protein kinase α1 (AMPKα1), reactive oxygen species (ROS), and apoptosis were tightly associated with each other in HEK293 cells treated with cisplatin. We demonstrated that AMPKα1 acted as an anti-oxidant factor and that ROS generated by cisplatin suppressed the expression of AMPKα1 at the transcriptional level, thereby resulting in induction of apoptosis. Treatment with GPHD or damulin B effectively prevented cisplatin-induced apoptosis of HEK293 cells and cisplatin-induced acute kidney injury in mice by suppressing oxidative stress and maintaining AMPKα1 levels. Therefore, our study suggests that GPHD and damulin B may serve as prospective adjuvant agents against cisplatin-induced nephrotoxicity.
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