428 research outputs found

    Vortex patterns and the critical rotational frequency in rotating dipolar Bose-Einstein condensates

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    Based on the two-dimensional mean-field equations for pancake-shaped dipolar Bose-Einstein condensates in a rotating frame with both attractive and repulsive dipole-dipole interaction (DDI) as well as arbitrary polarization angle, we study the profiles of the single vortex state and show how the critical rotational frequency change with the s-wave contact interaction strengths, DDI strengths and the polarization angles. In addition, we find numerically that at the `magic angle' ϑ=arccos(3/3)\vartheta=\arccos(\sqrt{3}/3), the critical rotational frequency is almost independent of the DDI strength. By numerically solving the dipolar GPE at high rotational speed, we identify different patterns of vortex lattices which strongly depend on the polarization direction. As a result, we undergo a study of vortex lattice structures for the whole regime of polarization direction and find evidence that the vortex lattice orientation tends to be aligned with the direction of the dipoles

    Olfaction in Host Plant Selection of the Soybean Aphid Aphis glycines

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    Results from a behavioral study using a four-armed olfactometer (Vet et al, 1983) showed that alate and apterous virginopara of Aphis glycines were clearly attracted or arrested by volatiles from Glycine max, its secondary host plant, and Rhamnus davurica, its primary host plant. The attractiveness of G. max was greater than that of R. davurica. Chemical analysis indicated that there is some difference in the volatile profiles between these two plant species. The volatiles from two nonhost plant species Gossypium hirsutrm and Cucumis sativa, which are the most suitable host plants of another aphid A. gossypii closely related to A. glycines, were found to be neutral. However, the odors of Luffa cylindrical and Cucurbita pepo significantly repelled the alate virginopara of A. glycines. Thus, the olfactory response of A. glycines to these host and nonhost plants implies the evolutionary transition of A. glycines in host plant specificity. Blending the odors from nonhost plants Gossypium hirsutum, Luffa cylindrical and Cucurbita pepo with the attractive odor of host plant G. max blocked the attractiveness of the latter to the alate virginopara of A. glycines. It thus appeared that attractiveness of host plant to aphids can be disrupted by the presence of nonhost plant volatiles which have presumably masked the host plant odor, and the lack of attractiveness of the blended odors is caused by the change in volatile profile.Originating text in Chinese.Citation: Du, Yongjun, Yan, Fushun, Han, Xinli, Zhang, Guangxue. (1994). Olfaction in Host Plant Selection of the Soybean Aphid Aphis glycines. Kun chong xue bao. Acta entomologica Sinica, 37(4), 385-392

    CLIP-KD: An Empirical Study of Distilling CLIP Models

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    CLIP has become a promising language-supervised visual pre-training framework and achieves excellent performance over a wide range of tasks. This paper aims to distill small CLIP models supervised by a large teacher CLIP model. We propose several distillation strategies, including relation, feature, gradient and contrastive paradigm, to examine the impact on CLIP distillation. We show that the simplest feature mimicry with MSE loss performs best. Moreover, interactive contrastive learning and relation-based distillation are also critical in performance improvement. We apply the unified method to distill several student networks trained on 15 million (image, text) pairs. Distillation improves the student CLIP models consistently over zero-shot ImageNet classification and cross-modal retrieval benchmarks. We hope our empirical study will become an important baseline for future CLIP distillation research. The code is available at \url{https://github.com/winycg/CLIP-KD}

    Time to Progress: the Impact of Temporal Ownership on Time Perception

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    Time is often linguistically portrayed either in a narrative or possessive framing. Building on this tendency, the authors demonstrate that communicating time in possession framing increases perceived ownership and feelings of responsibility towards making use of time. The heightened responsibility leads consumers to minimize time loss, but maximize time investment

    Exploring Structured Semantic Prior for Multi Label Recognition with Incomplete Labels

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    Multi-label recognition (MLR) with incomplete labels is very challenging. Recent works strive to explore the image-to-label correspondence in the vision-language model, \ie, CLIP, to compensate for insufficient annotations. In spite of promising performance, they generally overlook the valuable prior about the label-to-label correspondence. In this paper, we advocate remedying the deficiency of label supervision for the MLR with incomplete labels by deriving a structured semantic prior about the label-to-label correspondence via a semantic prior prompter. We then present a novel Semantic Correspondence Prompt Network (SCPNet), which can thoroughly explore the structured semantic prior. A Prior-Enhanced Self-Supervised Learning method is further introduced to enhance the use of the prior. Comprehensive experiments and analyses on several widely used benchmark datasets show that our method significantly outperforms existing methods on all datasets, well demonstrating the effectiveness and the superiority of our method. Our code will be available at https://github.com/jameslahm/SCPNet.Comment: Accepted by IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR) 202

    Experimental study on atomization characteristics of two common spiral channel pressure nozzles

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    Spiral channel pressure nozzles are commonly used pressure nozzles in practical workplaces. In this paper, two kinds of spiral channel type pressure nozzles, namely, spiral hole type and spiral non-porous type, the atomization characteristics and dust reduction efficiency under different spray pressures are discussed and compared. Based on the experimental method, based on the self-designed spray dust-reducing roadway experimental platform, the macro-atomization characteristics of the two nozzles, namely the flow rate, the atomization angle, the range, and the droplet size, were measured. The following conclusions were drawn: (1) The flow rates of both nozzles increase with increasing spray pressure, and the flow coefficient of the spiral non-porous nozzle is small. (2) The change of the atomization angle of the two nozzles first increases and then decreases with the increase of the spray pressure, and the atomization angle of the spiral non-porous nozzle is larger. At the same time, the range of the two nozzles gradually increases as the spray pressure increases, and the range of the spiral perforated nozzle is always larger than that of the spiral non-porous nozzle. (3) When the spray pressure is gradually increased, the droplet size of the two nozzles selected in the experiment is gradually reduced, and the droplet size of the spiral perforated nozzle is always larger than that of the spiral non-porous nozzle before 5 MPa, and then gradually Become smaller. The main reason why the droplet size decreases with the increase of the spray pressure is that the increase of the spray pressure leads to an increase in the spray speed of the water droplets, so that the water droplets are completely split when they are ejected from the nozzle, resulting in a smaller droplet size. In summary, when the spray pressure required in the actual working environment is low, the use of a spiral non-porous nozzle is more conducive to dust reduction
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