Journal of Visualization最新文献

Relation extraction is a vital task in constructing large-scale knowledge graphs, aiming to identify factual relations between entities from plain texts and generate triples. However, it is inevitable that a large amount of noise will be generated and should be given special attention; otherwise, they will seriously downgrade the performance of knowledge reasoning. In this paper, we propose a visual analytics system that facilitates automatic extraction and interactive optimization of relations between entities, enabling users to refine these extraction results with low confidence. First, a triple-based embedding method is designed to provide an overview of the triples by capturing the semantic similarity between entities and relations. Then, the contextual information in the embedding space is utilized to evaluate the correctness of triples and infer more probable relations for correction. Finally, a visual analysis system integrating the above method and multiple coordinated views is developed, enabling the higher-quality data corrected by users to assist in achieving iterative optimization of the relation extraction model in an interpretable way. Case studies based on real-world datasets and expert interviews further demonstrate the effectiveness of the system for effective analysis and exploration of the knowledge graph relation extraction.

Graphical abstract

Abstract

Infographics are visual representations designed for efficient and effective communication of data and knowledge. One crucial aspect of infographic design is the interplay between text and visual elements, particularly in circular visualizations where the textual descriptions can either be embedded within the graphics or placed adjacent to the visual representation. While several studies have examined text layout design in visualizations in general, the text-visual interplay in infographics and its subsequent perceptual effects remain underexplored. To address this, our study investigates how varying text placement and descriptiveness impact pleasantness, comprehension and overall memorability in the infographics viewing experience. We recruited 30 participants and presented them with a collection of 15 infographics across a diverse set of topics, including media and public events, health and nutrition, science and research, and sustainability. The text placement (embed, side to side) and descriptiveness (simplistic, normal, descriptive) were systematically manipulated, resulting in a total of six experimental conditions. Our key findings indicate that text placement can significantly influence the memorability of infographics, whereas descriptiveness can significantly impact the pleasantness of the viewing experience. Embedding text placement and simplistic text can potentially contribute to more effective infographic designs. These results offer valuable insights for infographic designers, contributing to the creation of more effective and memorable visual representations.

Graphic Abstract

To deepen the understanding of flow mechanisms related to corner separation and associated control techniques, a passive control scheme based on a vortex generator (VG) installed on the end wall of the cascade passage was adopted. Detailed particle image velocimetry investigations were performed at different attack angles and flow velocities in a low-speed wind tunnel. At a 5° attack angle, the VG control cascade can effectively suppress the corner separation for chord Reynolds numbers (Re_c) of 2.1 × 10⁴ and 3.1 × 10⁴. As Re_c increases to 3.8 × 10⁴ and 4.8 × 10⁴, the original separation zone is relatively small, and the strong trailing vortex generated by the VG fails to intersect it, instead producing excessive interference to the main flow, resulting in additional flow loss. The separation zone is generally small at a 0° attack angle, and the VG control cascade performs similarly to that at the 5° attack angle. Through analysis of the instantaneous velocity and vorticity, it is discovered that the primary mechanism by which the VG suppresses corner separation is the unsteady disturbance of the trailing vortex to the separation, which increases the kinetic energy in the separation zone, lowers the accumulation of low-energy fluid, thereby suppressing the corner separation.

Graphic Abstract

Abstract

Algae are often cultivated in closed system of photobioreactors. In the cultivation, algae cells grow to adhere on the wall surface of a reactor, which results in inhibiting photosynthesis of culture solution. This short paper visualizes the microalgae adhesion on the oil coated wall of a cultivation reactor. A remarkable finding is the fact that the coating of silicone oil could protect the wall surface from the microalgae adhesion. In particular, the coating of silicone oil with the kinematic viscosity larger than 20 [cSt] can be found to reduce the adhesion area on the reactor wall to less than half that on an uncoated reactor.

Graphical abstract

Large-scale numerical simulations are capable of generating data up to terabytes or even petabytes. As a promising method of data reduction, super-resolution (SR) has been widely studied in the scientific visualization community. However, most of them are based on deep convolutional neural networks or generative adversarial networks and the scale factor needs to be determined before constructing the network. As a result, a single training session only supports a fixed factor and has poor generalization ability. To address these problems, this paper proposes a flow feature-enhanced implicit neural representation (FFEINR) for spatiotemporal super-resolution of flow field data. It can take full advantage of the implicit neural representation in terms of model structure and sampling resolution. The neural representation is based on a fully connected network with periodic activation functions, which enables us to obtain lightweight models. The learned continuous representation can decode the low-resolution flow field input data to arbitrary spatial and temporal resolutions, allowing for flexible upsampling. The training process of FFEINR is facilitated by introducing feature enhancements for the input layer, which complements the contextual information of the flow field. To demonstrate the effectiveness of the proposed method, a series of experiments are conducted on different datasets by setting different hyperparameters. The results show that FFEINR achieves significantly better results than the trilinear interpolation method.

Graphical abstract

The flow characteristics in centrifugal pump are complicated due to its complex geometry structure. Based on micro-internal circulation experimental bench and high-frequency PIV system, the velocity field at different experimental conditions is measured and the velocity values under different PIV sample frequencies are compared and analyzed. The results indicate that within the relative velocity error limit of 5%, the minimum sample frequency of the high-frequency PIV system should be greater than 2000 Hz for the impeller with speed of 600 r/min at design condition. While the speeds of the impeller are 400 r/min and 500 r/min, the minimum sample frequency must be higher than 1428 Hz and 1667 Hz, respectively. The minimum sample frequency only needs to reach about 1111 Hz when the impeller speed is reduced to 300 r/min. However, it requires a higher minimum sample frequency for the impeller at part-load conditions. The minimum sample frequency should be higher than 3333 Hz, 2500 Hz and 2000 Hz for the impeller speed with 600 r/min, 500 r/min and 400 r/min, respectively. When the impeller speed is less than 600 r/min, the sample frequency of high-frequency PIV system should not exceed 5000 Hz. The results provide important reference indicators for the construction of high-frequency PIV system used in centrifugal pumps.

Graphical abstract

We experimentally studied the wake flow behind a submerged vertical cylinder in an open channel rotating at a constant angular velocity around a vertical axis. We obtained the two-dimensional velocity field on the free surface of fluid by a Particle Image Velocimetry measurement. In some cases, we found the emergence of a steady vortex perpendicular to the surface and vortex-shedding behind it. The necessary condition for the emergence of such vortices is given by the excess of Rossby number below a critical value, which is determined by the relative height of the cylinder. Reynolds number must be large enough, and the thresholding value depends on the relative height.

Graphical abstract

Abstract

The flow around a square cylinder with a synthetic jet positioned at the rear surface is numerically investigated with unsteady Reynolds-averaged Navier–Stokes (URANS) method. Different exciting signals are utilized to generate the synthetic jets, including the square signal, triangle signal, sinusoidal signal and the varying duty-cycle signal. The wake vortices evolution and the frequency characteristic are analyzed for all the cases. In the case with the square signal, the vortex shedding pattern is not essentially changed due to the deficiency of the synthetic jet strength. The synchronization at half of the exciting frequency is observed for both of the sinusoidal and triangle signal, where the alternative deflection of the jet vortex pairs is detected correspondingly. The complete synchronization is discovered in the case with the duty-cycle (k=2) signal, where the wake is symmetrical and totally controlled by the synthetic jets. The drag coefficient is calculated to contrast the control efficiency of different signals. The most satisfactory control performance is achieved in the case with the duty cycle (k=2) signal as well, where a (33.71%) of drag reduction is realized compared to that without control.

Graphical abstract