73 research outputs found
In-phase schooling hinders linear acceleration in wavy hydrofoils paired in parallel across various wavelengths
This study examines the impact of in-phase schooling on the hydrodynamic
efficiency during linear acceleration in a simplified model using two
undulating NACA0012 hydrofoils arranged in phalanx formation as a minimal
representation of a fish school. The research focuses on key parameters, namely
Strouhal (0.2-0.7) and Reynolds (1000-2000) numbers, and explores the effect of
varying fish-body wavelengths (0.5-2), reflecting natural changes during actual
fish linear acceleration. Contrary to expectations, in-phase schooling did not
enhance acceleration performance. Both propulsive efficiency and net thrust
were found to be lower compared to solitary swimming and anti-phase schooling
conditions. The study also identifies and categorizes five distinct flow
structure patterns within the parameters investigated, providing insight into
the fluid dynamics of schooling fish during acceleration.Comment: 19 pages, more authors to be confirmed and added in the futur
Research on the impact of green finance on carbon emissions: evidence from China
Green finance is an effective means adopted by the Chinese government to reduce carbon emissions. Does the development of
green finance in Chinese provinces reduce carbon emissions to a
certain extent? This study selects panel data of various provinces
and cities in China from 2003 to 2019. Based on the Hansen
threshold regression model, an empirical analysis is conducted
with economic growth and industrial structure as threshold variables to test the impact of green finance on carbon emissions. The
results show that green finance increases the speed of carbon
emission mitigation when PGDP is the threshold. Taking industrial
structure as the threshold, the impact of green finance development on carbon emissions presents an inverted N shape. At the
same time, it is found that green finance has become an important means to reduce carbon emissions in the eastern region, the
impact of green finance on carbon emissions in the central region
presents an inverted U shape, and the driving force of green
finance on carbon emission reduction in the western region is
weak. Furthermore, it is pointed out that improving the quality of
green finance and enhancing the level of green finance empowered by science and technology are the keys to realizing sustainable green development
How Biomimetic Morphing Dorsal Fin Affects the Swimming Performance of a Free-swimming Tuna Robot
It is well known that tuna fish in the ocean can dynamically morph their
median fins to achieve optimal hydrodynamic performance, e.g. linear
acceleration and maneuverability. In this study, based on the previous studies
about the median fin's hydrodynamic effects focusing on tethered conditions, we
continue to explore the hydrodynamic function of tuna morphing dorsal fin in
free swimming conditions for better approaching real-life situations.Here, we
developed a tuna-inspired robotic fish platform that can swim independently in
three dimensions, equipped with a biomimetic morphing dorsal fin magnetically
attached to the robotic fish. Based on the free-swimming robotic fish platform,
we investigated how the erected dorsal fin affects the speed, cost of transport
(COT), and robotic fish's yaw angle at different frequencies and amplitudes.
The erected dorsal fin plays a positive role in improving the yaw stability of
robotic fish. However, it shows little influence on the speed and COT in our
test. This remains to be further investigated in the future.Comment: 10 pages, 5 figures, 2 table
Stimulus Complexity and Chunk Tightness Interact to Impede Perceptual Restructuring During Problem Solving
The mutual influence of stimulus complexity and chunk tightness on perceptual restructuring was examined using a chunk decomposition task (CDT). Participants attempted to remove components of Chinese characters in order to produce new, valid characters. Participants had their electroencephalogram recorded while completing a CDT in conditions of low or high stimulus complexity, crossed with two levels of chunk tightness. Tight chunks overlapped spatially whereas loose chunks did not. Both increasing chunk tightness and increasing stimulus complexity impaired performance (lower accuracy, longer reaction times), and these factors interacted such that highly complex, tight chunks produced the worst performance. These factors also had interacting effects on the late positive complex (LPC). The LPC amplitude was reduced by increasing chunk tightness, but this effect was attenuated for highly complex stimuli. These results suggest that though chunk tightness and stimulus complexity impair performance in the CDT, they have dissociable neural underpinnings
The role of element type and crossed relation in restructuring difficulty
Chunk decomposition is an aspect of problem solving that involves decomposing a pattern into its component parts in order to regroup them into a new pattern. Previous work suggests that the primary source of difficulty in chunk decomposition is whether a problem’s solution requires removing a part that is a meaningful perceptual pattern (termed a chunk) or not (a non-chunk). However, the role of spatial overlap (crossed relation or not) has been ignored in this line of research. Here, we dissociated the role of element type and crossed relation in chunk decomposition problems by employing a Chinese character transformation task. We replicated the finding that when the to-be-removed element is a non-chunk, the problem is more difficult to solve than when the element is a chunk. However, this result held only if the elements had no crossed relation. Relative to non-crossed relation, problems that involved removing elements that overlapped with the remaining character were more difficult to solve irrespective of the element type. We conclude that both element type and crossed relation can cause the difficulty of chunk decomposition and crossed relation plays more important role in preventing people from finding insightful ways to decompose chunk relative to element type
How wavelength affects the hydrodynamic performance of two accelerating mirror-symmetric slender swimmers
Fish schools are capable of simultaneous linear acceleration. To reveal the
underlying hydrodynamic mechanism, we numerically investigate how Reynolds
number , Strouhal number and wavelength
affect the mean net thrust and net propulsive efficiency
of two side-by-side hydrofoils undulating in anti-phase. In total,
cases are simulated using immersed boundary method. The thrust increases
significantly with wavelength and Strouhal number, yet only slightly with the
Reynolds number. We apply a symbolic regression algorithm to formulate this
relationship. Furthermore, we find that mirror-symmetric schooling can achieve
a \textit{net} thrust more than ten times that of a single swimmer, especially
at low Reynolds numbers. The highest efficiency is obtained at and
, where is consistent with that observed in the
linear-accelerating natural swimmers, \eg Crevalle jack. Six distinct flow
structures are identified. The highest thrust corresponds to an asymmetric flow
pattern, whereas the highest efficiency occurs when the flow is symmetric with
converging vortex streets.Comment: This paper has been accepted by Physics of Fluids. This is the
accepted versio
Identification and Transformation Difficulty in Problem Solving: Electrophysiological Evidence from Chunk Decomposition
A wealth of studies have investigated how to overcome experience-based constraints in creative problem solving. One such experience-based constraint is the tendency for people to view tightly organized visual stimuli as single, unified percepts, even when decomposition of those stimuli into component parts (termed chunk decomposition) would facilitate problem solving. The current study investigates the neural underpinnings of chunk decomposition in creative problem solving by analyzing event-related potentials. In two experiments, participants decomposed Chinese characters into the character’s component elements and then used the base elements to form a new valid character. The action could require decomposing a “tight” chunk, meaning that the component elements intersected spatially, or a “loose” chunk, in which the component elements did not overlap in space. Behaviorally, individuals made more errors and responded slower to trials involving tight chunks relative to loose chunks. Analysis of the ERPs revealed that relative to loose chunks, the electrophysiological response to tight chunks contained an increased N2, an increased N400, and a decreased late positive complex. Taken together, these results suggest that chunk tightness is a principle determinant of the difficulty of chunk decomposition, and that chunk tightness provokes neural conflict and semantic violations, factors known to influence the N2 and N400 ERP components
Comparative analyses of transcriptome and proteome in response to cotton bollworm between a resistant wild soybean and a susceptible soybean cultivar
Syntheses, Characterization and Crystal Structures of Dicyanamide Bridged Polynuclear Copper(II) and Zinc(II) Complexes with Urease Inhibitory Activity
A pair of structurally similar dicyanamide bridged copper(II) and zinc(II) complexes [CuL(dca)]n (1) and [ZnL(dca)]n (2), were prepared from the fluorine containing Schiff base 5-fluoro-2-(((2-hydroxyethyl)imino)methyl)phenol (HL). The compounds were characterized by physico-chemical methods. Structures of the complexes were confirmed by single crystal X-ray diffraction. The Cu atom in complex 1 is in square pyramidal coordination, whereas the Zn atom in complex 2 is in trigonal bipyramidal coordination. The copper complex has effective Jack bean urease inhibitory activity, with IC50 value of 0.14±0.12 μmol L–1.
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Approaching the Distinction between Intuition and Insight
Intuition and insight share similar cognitive and neural basis. Though, there are still some essential differences between the two. Here in this short review, we discriminated between intuition and insight in two aspects. First, intuition and insight are towards different aspects of information processing. Whereas intuition involves judgment about yes or no, insight is related to what is the solution. Second, tacit knowledge play different roles in between intuition and insight. On the one hand, tacit knowledge is conducive to intuitive judgment. On the other hand, tacit knowledge may first impede but later facilitate insight occurrence. Furthermore, we share theoretical and methodological views on how to access the distinction between intuition and insight
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