Investigation of Turn Number of the Coil on Tube Forming Performance in Electromagnetic Pulse Forming

Electromagnetic pulse forming (EMPF) is an environmentally friendly and high-speed forming method without pollution generating. As the key component for energy conversion, the coil has a significant influence on the forming performance. Consequently, this paper aims to study the effect of the turn number of the coil on the performance of the tube forming through the theoretical analysis model and experiments. Based on the connection among the electrical parameters of the coil, the current parameters of the discharge pulse, and electromagnetic force, a theoretical model is built to analyze the qualitative connection between the number of turns of the coil and the amount of forming. Then, the EMPF experiments with the same discharge energy of 3.4kJ are carried out to verify the established model through the established EMPF equipment. The experimental results are consistent with the theoretical analysis. The results show that the peak value of the current amplitude and rise time of the pulse decrease respectively with the increase of the number of turns of the coil because the increments of the number of turns lead to the rising coil inductance. But the forming amount of the tube increases first and then decreases. So there is an optimal value of the turn number for the coil to generate the maximum Lorentz force to deform the workpiece. Therefore, it is worthwhile to choose the proper number of coil turn to improve the effect of EMPF

Biodiversity surveys reveal eight new species of freshwater crabs (Decapoda: Brachyura: Potamidae) from Yunnan Province, China

Yunnan Province is known to host the highest species diversity of the true freshwater crabs in China; 50 species have been recorded from the province by 2017. In 2004, our team conducted a biodiversity survey of the freshwater crabs in Yunnan Province to determine how well the diversity of crabs in the area has been characterized. We collected a total of 25 species, of which nine species proved to be new to science, and eight of which are described here. These include four species of the genus Indochinamon Yeo & Ng, 2007, two species of the genus Potamiscus Alcock, 1909, and one species each of the genera Pararanguna Dai & Chen, 1985, and Parvuspotamon Dai & Bo, 1994. The new species of Pararanguna and Parvuspotamon represent the second species of respective genera, which are here redefined. Detailed comparisons with morphologically allied species are provided. Photographs of the type specimens of their comparative species which are poorly illustrated in the literature are also provided to allow better understanding of their morphology. This study brings the number of the freshwater crabs of Yunnan Province to 58. Since about 13.8% of the number of species (eight out of 58 species) is increased by surveys conducted within a relatively short period, it is most probable that the species diversity of this group is still understudied in Yunnan Province

Preparation and Device Applications of Ferroelectric β-PVDF Films

Organic ferroelectric materials have unique characters comparing to their inorganic counterparts in electronics because they show the advantages such as low cost, lightweight, small thermal budget, flexible and nontoxic characteristics. The ferroelectric poly(vinylidene fluoride) (PVDF) is mostly desired for memory devices due to its polar phase. To obtain the ferroelectric memory devices for data storage, ultrathin PVDF films are required to allow for low operation voltages with both small roughness and free of pin-holes. Micron-meter thick films of ferroelectric phase PVDF can be easily achieved by many preparation methods. But the nanofilms could be mainly fabricated by coating method and Langmuir–Blodgett deposition technique. Meanwhile, according to the structure of devices, four types of organic memory cells using ferroelectric phase PVDF films were introduced, such as memory based on metal/organic semiconductor/metal ferroelectric tunnel junctions, organic capacitors, field effect transistor and organic diodes. The research has been mainly done in Zhang’s laboratory from September 2016 to explore the preparation and potential applications of ferroelectric PVDF films. In this chapter, we summarize several device investigations and show the PVDF films have the promising memory applications

CSST Strong Lensing Preparation: a Framework for Detecting Strong Lenses in the Multi-color Imaging Survey by the China Survey Space Telescope (CSST)

Strong gravitational lensing is a powerful tool for investigating dark matter and dark energy properties. With the advent of large-scale sky surveys, we can discover strong lensing systems on an unprecedented scale, which requires efficient tools to extract them from billions of astronomical objects. The existing mainstream lens-finding tools are based on machine learning algorithms and applied to cut-out-centered galaxies. However, according to the design and survey strategy of optical surveys by CSST, preparing cutouts with multiple bands requires considerable efforts. To overcome these challenges, we have developed a framework based on a hierarchical visual Transformer with a sliding window technique to search for strong lensing systems within entire images. Moreover, given that multi-color images of strong lensing systems can provide insights into their physical characteristics, our framework is specifically crafted to identify strong lensing systems in images with any number of channels. As evaluated using CSST mock data based on an Semi-Analytic Model named CosmoDC2, our framework achieves precision and recall rates of 0.98 and 0.90, respectively. To evaluate the effectiveness of our method in real observations, we have applied it to a subset of images from the DESI Legacy Imaging Surveys and media images from Euclid Early Release Observations. 61 new strong lensing system candidates are discovered by our method. However, we also identified false positives arising primarily from the simplified galaxy morphology assumptions within the simulation. This underscores the practical limitations of our approach while simultaneously highlighting potential avenues for future improvements.Comment: The paper is accepted by the AJ. The complete code could be downloaded with DOI of: 10.12149/101393. Comments are welcom

DNA Repair in Human Pluripotent Stem Cells Is Distinct from That in Non-Pluripotent Human Cells

The potential for human disease treatment using human pluripotent stem cells, including embryonic stem cells and induced pluripotent stem cells (iPSCs), also carries the risk of added genomic instability. Genomic instability is most often linked to DNA repair deficiencies, which indicates that screening/characterization of possible repair deficiencies in pluripotent human stem cells should be a necessary step prior to their clinical and research use. In this study, a comparison of DNA repair pathways in pluripotent cells, as compared to those in non-pluripotent cells, demonstrated that DNA repair capacities of pluripotent cell lines were more heterogeneous than those of differentiated lines examined and were generally greater. Although pluripotent cells had high DNA repair capacities for nucleotide excision repair, we show that ultraviolet radiation at low fluxes induced an apoptotic response in these cells, while differentiated cells lacked response to this stimulus, and note that pluripotent cells had a similar apoptotic response to alkylating agent damage. This sensitivity of pluripotent cells to damage is notable since viable pluripotent cells exhibit less ultraviolet light-induced DNA damage than do differentiated cells that receive the same flux. In addition, the importance of screening pluripotent cells for DNA repair defects was highlighted by an iPSC line that demonstrated a normal spectral karyotype, but showed both microsatellite instability and reduced DNA repair capacities in three out of four DNA repair pathways examined. Together, these results demonstrate a need to evaluate DNA repair capacities in pluripotent cell lines, in order to characterize their genomic stability, prior to their pre-clinical and clinical use

ELASTIC-PLASTIC ANALYSIS OF 3D MACRO-MICRO TWO SCALE MODEL WITH LINEAR MIXED HARDENING

The theory of macro-micro two scale model obtains the micro plastic strains by using the macro-micro connecting factor,which is an effective theory to investigate the damage accumulation of the high fatigue and its failure mechanism.Based on the macro-micro theory,the evolution rule of the micro stresses and strains with plastic hardening was studied,and it solved the micro stresses and strains of the three-dimensional models by making programs,which considered the linear mixed plastic hardening.It established the 3 D finite element models,and calculated the micro stresses and strains and obtains the equivalent stress-strain hysteresis loops with linear mixed hardening.Compared with the finite element results,the effectiveness of the algorithm results is verified

Two new species of freshwater crabs of the genus Heterochelamon Türkay & Dai, 1997 (Crustacea: Decapoda: Brachyura: Potamidae) from Guangxi Zhuang Autonomous Region, southern China

Naruse, Tohru, Zhu, Chunchao, Zhou, Xianmin (2013): Two new species of freshwater crabs of the genus Heterochelamon Türkay & Dai, 1997 (Crustacea: Decapoda: Brachyura: Potamidae) from Guangxi Zhuang Autonomous Region, southern China. Zootaxa 3647 (4): 567-576, DOI: 10.11646/zootaxa.3647.4.