The dynamic simulation analysis of the coupling vibration of a maglev levitation frame and the levitation control system

To study the characteristics of the coupling vibration between the maglev vehicle and the track beam system, a new type of vibration test bench model was developed. Take the single maglev levitation frame as the study object, the structural characteristics of the maglev vehicle can be adequately considered in the research. Further more, the variable stiffness of the track beam makes the frequency conversion simulation possible. In addition, all types of real track irregularity excitations can be simulated through the test bench dynamics model. Based on the model, the influence of the track beam support stiffness, the track irregularity and the local support deficiency on the levitation control performance was determined using the dynamics simulation method, and the vibration resonance phenomenon of the vehicle/track system was reproduced by the dynamics simulation, too. The developed of the model can increase the research progress of the maglev dynamics research

Measurements of the inclusive jet cross section and jet fragmentation in pp collisions with the ALICE experiment at the LHC

Jet reconstruction and jet fragmentation variables provide important information to study the interaction between hard scattered partons and the Quark-Gluon Plasma. This paper presents the measurement of the inclusive cross section for fully reconstructed jets in pp collisions at sqrt(s) = 2.76 TeV, which provides an essential reference for jet measurements in Pb-Pb collisions at the same sqrt(s_NN). In addition, we report jet fragmentation measurements for charged particle jets in pp collisions at sqrt(s) = 7 TeV. These measurements utilize the ALICE central barrel tracking system to detect charged particles with good efficiency above 150 MeV/c, together with the Electromagnetic Calorimeter (EMCal). The jet cross section and fragmentation measurements are compared to theoretical calculations and Monte Carlo generators.Comment: 4 page, 6 figures, proceeding for the Fifth International Conference on Hard and Electromagnetic Probes of High Energy Nuclear Collisions (Hard Probes 2012), May 27 - June 1, Cagliari, Ital

A broadband polygonal cloak for acoustic wave designed with linear coordinate transformation

Previous acoustic cloaks designed with transformation acoustics always involve inhomogeneous material. In this paper, a design of acoustic polygonal cloak is proposed using linear polygonal transformation method. The designed acoustic polygonal cloak has homogeneous and anisotropic parameters, which is much easier to realize in practice. Furthermore, a possible acoustic metamaterial structure to realize the cloak is proposed. Simulation results on the real structure show that the metamaterial acoustic cloak is effective to reduce the scattering of the object.National Natural Science Foundation (China) (Grants 61322501, 61574127, and 61275183)Program for New Century Excellent Talents in University (China) (NCET-12-0489)Fundamental Research Funds for the Central Universities of ChinaZhejiang University. Innovation Joint Research Center for Cyber-Physical-Society SystemChina Postdoctoral Science FoundationUnited States. Office of Naval Research. Multidisciplinary University Research Initiative (Grant 2015M581930)Top-Notch Young Talents Program of Chin

Experimental study on the isothermal adsorption of methane gas in natural gas hydrate argillaceous silt reservoir

Gas hydrate occurs in hydrate reservoirs in a solid form. At present, the conventional exploitation method is to decompose solid hydrate and then extract the resulting gaseous gas. Therefore, the occurrence law of gas in a reservoir is of great significance for the study of gas hydrate seepage and productivity. Adsorption, as an important occurrence mode, has been widely concerned in the research on shale reservoirs. However, the adsorption problem in hydrate reservoirs has not received enough attention. In this paper, the existence of adsorption in a hydrate reservoir has been experimentally confirmed for the first time. Based on the argillaceous silt of a natural gas hydrate reservoir in the South China Sea, the pore structure and adsorption characteristics of argillaceous silt were experimentally studied, and the results were compared with those of typical shale reservoirs. The modified Langmuir and Dubinin-Radushevich equations were used to fit the adsorption data, and the suitable adsorption model of argillaceous silt was established and optimized. The results showed that the inhomogeneous slit pores are dominant in argillaceous silt, and they are formed by the accumulation of lamellar particles. Compared with shale, the adsorption capacity of argillaceous silt is weak under the same conditions. However, adsorption is a spontaneous exothermic reaction, and the ambient temperature of argillaceous silt is much lower than that of shale. Therefore, it is possible for argillaceous silt to achieve an adsorption capacity comparable to that of shale. The modified Langmuir model can be used to simulate argillaceous silt adsorption at low pressure, while under medium and high pressures, the modified Dubinin-Radushevich model performs better. The adsorption capacity of argillaceous silt is affected by moisture. When the water content is 20%, the Langmuir adsorption capacity and the Dubinin-Radushevich maximum adsorption capacity decreases by 21.88% and 13.67%, respectively, which is far less than the influence of moisture on shale adsorption, as reported in the literature.Cited as: Qi, R., Qin, X., Lu, C., Ma, C., Mao, W., Zhang, W. Experimental study on the isothermal adsorption of methane gas in natural gas hydrate argillaceous silt reservoir. Advances in Geo-Energy Research, 2022, 6(2): 143-156. https://doi.org/10.46690/ager.2022.02.0

X-CLIP: End-to-End Multi-grained Contrastive Learning for Video-Text Retrieval

Video-text retrieval has been a crucial and fundamental task in multi-modal research. The development of video-text retrieval has been considerably promoted by large-scale multi-modal contrastive pre-training, which primarily focuses on coarse-grained or fine-grained contrast. However, cross-grained contrast, which is the contrast between coarse-grained representations and fine-grained representations, has rarely been explored in prior research. Compared with fine-grained or coarse-grained contrasts, cross-grained contrast calculate the correlation between coarse-grained features and each fine-grained feature, and is able to filter out the unnecessary fine-grained features guided by the coarse-grained feature during similarity calculation, thus improving the accuracy of retrieval. To this end, this paper presents a novel multi-grained contrastive model, namely X-CLIP, for video-text retrieval. However, another challenge lies in the similarity aggregation problem, which aims to aggregate fine-grained and cross-grained similarity matrices to instance-level similarity. To address this challenge, we propose the Attention Over Similarity Matrix (AOSM) module to make the model focus on the contrast between essential frames and words, thus lowering the impact of unnecessary frames and words on retrieval results. With multi-grained contrast and the proposed AOSM module, X-CLIP achieves outstanding performance on five widely-used video-text retrieval datasets, including MSR-VTT (49.3 R@1), MSVD (50.4 R@1), LSMDC (26.1 R@1), DiDeMo (47.8 R@1) and ActivityNet (46.2 R@1). It outperforms the previous state-of-theart by +6.3%, +6.6%, +11.1%, +6.7%, +3.8% relative improvements on these benchmarks, demonstrating the superiority of multi-grained contrast and AOSM.Comment: 13 pages, 6 figures, ACMMM2