64 research outputs found
Reducing Perceived Urban Rail Transfer Time with Ordinal Logistic Regressions
In order to improve the transfers inside an Urban Rail Transit (URT) station between different rail transit lines, this research newly develops two Ordinal Logistic Regression (OLR) models to explore effective ways for saving the Perceived Transfer Time (PTT) of URT passengers, taking into account the difficulty of improving the transfer infrastructure. It is validated that the new OLR models are able to rationally explain probabilistically the correlations between PTT and its determinants. Moreover, the modelling analyses in this work have found that PTT will be effectively decreased if the severe transfer walking congestion is released to be acceptable. Furthermore, the congestion on the platform should be completely eliminated for the evident reduction of PTT. In addition, decreasing the actual transfer waiting time of the URT passengers to less than 5 minutes will obviously decrease PTT.</p
An Improved Multiobjective PSO for the Scheduling Problem of Panel Block Construction
Uncertainty is common in ship construction. However, few studies have focused on scheduling problems under uncertainty in shipbuilding. This paper formulates the scheduling problem of panel block construction as a multiobjective fuzzy flow shop scheduling problem (FSSP) with a fuzzy processing time, a fuzzy due date, and the just-in-time (JIT) concept. An improved multiobjective particle swarm optimization called MOPSO-M is developed to solve the scheduling problem. MOPSO-M utilizes a ranked-order-value rule to convert the continuous position of particles into the discrete permutations of jobs, and an available mapping is employed to obtain the precedence-based permutation of the jobs. In addition, to improve the performance of MOPSO-M, archive maintenance is combined with global best position selection, and mutation and a velocity constriction mechanism are introduced into the algorithm. The feasibility and effectiveness of MOPSO-M are assessed in comparison with general MOPSO and nondominated sorting genetic algorithm-II (NSGA-II)
Weakly Supervised Video Representation Learning with Unaligned Text for Sequential Videos
Sequential video understanding, as an emerging video understanding task, has
driven lots of researchers' attention because of its goal-oriented nature. This
paper studies weakly supervised sequential video understanding where the
accurate time-stamp level text-video alignment is not provided. We solve this
task by borrowing ideas from CLIP. Specifically, we use a transformer to
aggregate frame-level features for video representation and use a pre-trained
text encoder to encode the texts corresponding to each action and the whole
video, respectively. To model the correspondence between text and video, we
propose a multiple granularity loss, where the video-paragraph contrastive loss
enforces matching between the whole video and the complete script, and a
fine-grained frame-sentence contrastive loss enforces the matching between each
action and its description. As the frame-sentence correspondence is not
available, we propose to use the fact that video actions happen sequentially in
the temporal domain to generate pseudo frame-sentence correspondence and
supervise the network training with the pseudo labels. Extensive experiments on
video sequence verification and text-to-video matching show that our method
outperforms baselines by a large margin, which validates the effectiveness of
our proposed approach. Code is available at https://github.com/svip-lab/WeakSVRComment: CVPR 2023. Code: https://github.com/svip-lab/WeakSV
An Improved Multiobjective PSO for the Scheduling Problem of Panel Block Construction
Uncertainty is common in ship construction. However, few studies have focused on scheduling problems under uncertainty in shipbuilding. This paper formulates the scheduling problem of panel block construction as a multiobjective fuzzy flow shop scheduling problem (FSSP) with a fuzzy processing time, a fuzzy due date, and the just-in-time (JIT) concept. An improved multiobjective particle swarm optimization called MOPSO-M is developed to solve the scheduling problem. MOPSO-M utilizes a ranked-order-value rule to convert the continuous position of particles into the discrete permutations of jobs, and an available mapping is employed to obtain the precedence-based permutation of the jobs. In addition, to improve the performance of MOPSO-M, archive maintenance is combined with global best position selection, and mutation and a velocity constriction mechanism are introduced into the algorithm. The feasibility and effectiveness of MOPSO-M are assessed in comparison with general MOPSO and nondominated sorting genetic algorithm-II (NSGA-II)
Robust estimation of bacterial cell count from optical density
Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data
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