Reliable dynamic mechanical properties of high nitrogen steels are necessary for the design and assessment of armor structures subject to impact and blast.A series of experiments,based on Hopkinson ...bar techniques,were conducted and described in this study.The dynamic compression,tensile and shear properties of high nitrogen steel had been tested,and the stress-strain curves under high strain rates were obtained.The results have been showed as follows:High nitrogen steel has a remarkable strain rate strengthening effect.Compared to the static curves,the constitutive curves of dynamic tension and compression move upper.The dynamic compressive yield strength of high nitrogen steel increases first and then decreases with the increase of strain rate,and the yield strength varies in the range of 1465 -1549 MPa within the range of 1147-2042 s-1 strain rate;The tensile strength of high nitrogen steel increases with the increase of strain rate.When the strain rate is greater than 1341 s-1,the tensile strength will not increase and the curve tends to be gentle.The pure shear yield strength of the high nitrogen steel is above 800 MPa.
Valve orifice is the common place that the cavitation easily occurs in the hydraulic systems. This paper introduces a criteria to estimate the inception of the cavitation of the V-type valve orifice ...with the stress state. Based on this criteria, a cavitation model which considers the dynamics of the cavity and incompressible gas is proposed to analyze the pressure, stress and the cavitation distribution of the phase in the V-type orifice. The distributions of the cavitation along the axis and the cross section are analyzed. The simulation results show that the cavitation is easily occurred in the downstream just after the orifice and the bubbles are mostly gathered in the top of the cross section which is vertical to the axis of the flow field. The simulation results is reasonable according to the facts. Accordingly, the cavitation of the V-type orifice is predicted reasonably. The research and results of this paper are useful for the design of the hydraulic valves.
The sensor selection problem was investigated for the application of classification of a set of ginsengs using a metal-oxide sensor-based homemade electronic nose with linear discriminant analysis. ...Samples (315) were measured for nine kinds of ginsengs using 12 sensors. We investigated the classification performances of combinations of 12 sensors for the overall discrimination of combinations of nine ginsengs. The minimum numbers of sensors for discriminating each sample set to obtain an optimal classification performance were defined. The relation of the minimum numbers of sensors with number of samples in the sample set was revealed. The results showed that as the number of samples increased, the average minimum number of sensors increased, while the increment decreased gradually and the average optimal classification rate decreased gradually. Moreover, a new approach of sensor selection was proposed to estimate and compare the effective information capacity of each sensor.
Abstract
A series of biaryl‐bridged salalen ligands together with their titanium complexes have been designed and synthesized. The Ti complexes could serve as highly efficient catalysts for the ...asymmetric epoxidation of a wide range of olefins, giving the corresponding epoxides with high
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values.
Inflammation and lung function decline are the main pathophysiological features of chronic obstructive pulmonary disease (COPD). Acupuncture can improve lung function in patients with COPD, but the ...underlying mechanisms are not well understood. Orexins (OXs), which are found in peripheral plasma, are neuropeptides that regulate respiration and their levels are related to COPD. Therefore, we hypothesized that acupuncture might alter OXs, reduce lung inflammation and improve lung function in COPD.
COPD was induced in rats by exposure to cigarette smoke for 8 weeks and injecting with lipopolysaccharide twice. Electroacupuncture (EA) was performed at Feishu (BL13) and Zusanli (ST36) for 30 min/d for 2 weeks. Rat lung function and morphology were assessed after EA. The levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in bronchoalveolar lavage fluid (BALF) and orexin A and B levels in the lung tissue were detected by enzyme-linked immunosorbent assay. OX receptor mRNA levels and immunopositive cells were assessed with real-time polymerase chain reaction and immunohistochemical methods, respectively. The relationships among lung function, cell factors, and OX levels were analyzed by Pearson correlation analyses.
Compared with the control group, lung function was significantly decreased in the rats with COPD (P<0.05). There were obvious increases in TNF-α and IL-1β levels in BALF (P<0.05 and P<0.01, respectively), orexin A level in lung tissue (P<0.01; but not orexin B) and mRNA expressions of OX 1 type receptor (OXR1) and OX 2 type receptor (OXR2) in lung tissue (P<0.05 and P<0.01, respectively); the integrative optical densities (IODs) of both receptors were greater in the COPD group (P<0.05). For rats with COPD subjected to EA, lung function was improved (P<0.05). There were notable decreases in TNF-α and IL-1β levels (P<0.05 and <0.01, respectively) in BALF. Orexin A, but not orexin B, levels in lung tissue also decreased (P<0.01), as did mRNA expression of OX1R and OX2R in lung tissue (P<0.05 and P<0.01, respectively). Receptor IODs were also reduced after EA treatment (P<0.05). Furthermore, orexin A levels and ratio of forced expiratory volume in 0.3 s to forced vital capacity were strongly negatively correlated (P<0.01), and orexin A was positively correlated with TNF-α and IL-1β (P<0.001 and P<0.05, respectively).
EA at Zusanli and Feishu improved lung function of rats with COPD and had an anti-inflammatory effect, which may be related to down-regulation of OXA and its receptors.
For the problems of the Multi-Bernoulli filter (MBF) in the multi-target tracking filed, such as the newborn targets cannot be detected, the tracking accuracy decreases or the targets are ...underestimated when the targets are occluded, and the underestimated targets cannot be associated with their previous tracks when they are redetected. The YOLOv3 method is introduced to predetect the targets under the framework of MBF, and then the predetected targets are presented by the convolution features and their similarity matrix are calculated between the adjacent frames. The detection strategy is proposed to realize the discrimination of newborn target. The reiden-tifiable strategy is proposed to achieve the continuous estimation of underestimated targets. In addition, when the template is updated, the high-confidence detection is integrated, and the occluded target processing mechanism is proposed to effectively improve the accuracy of target tracking. Finally, the proposed algorithm is tested on some challenging v
With the development of economy and the upgrading concept of people's consumption, the market potential of fashion industry has been tapped greatly. More attention has been paid to garment analysis. ...However, the machine analysis of clothes is vulnerable to the influence of scale and deformation. In this paper, we present an algorithm of locating key points of women's clothing based on human posture estimation technology. By transferring human posture estimation technology to this application, the algorithm can not only help overcome the above influences, but also promote the improvement of the effects of position alignment, local attribute recognition and automatic editing of clothing image. The innovation points of this paper are summarized as follows: firstly, in the coding stage, the bottom-up path enhancement method is adopted to improve the feature fusion ability of the coding structure of the basic network; secondly, in the decoding stage, simplifying the RefineNet structure of CPN network improves the accuracy while increasing the speed; thirdly, Integral regression method is used in this paper, which combined the advantages of heatmap and key points regression. Extensive experiment results show that the proposed algorithm can outperform CPN in COCO database.
High intensity discharge (HID) lamps take up a large percentage of the power consumption in the lighting. It is common to operate the HID lamps in 100% lighting state due to the difficulty of dimming ...control. This paper proposes a simple dimming method for them and manages to dim the lamp group collectively. A frequency control device is inserted between the power supply and the HID magnetic ballast. Because of the use of inductor in the magnetic ballast, its impedance increases with the frequency. Therefore, by changing the output frequency, the current flowing through HID lamps can be decreased/increased with the voltage being kept constant. Also, the generated waveforms of the frequency control device is discussed in this paper. Both simulation and experimental results are given to prove the dimming effect.
Objective： To explore the feasibility of using regenerated silk fibroin membrane to construct artificial skin substitutes for wound healing, it is necessary to evaluate its cytocompatibility. ...Methods： The effects of regenerated silk fibroin film on cytotoxicity, adhesion, cell cycle, and apoptosis of L929 cells, growth and vascular endothelial growth factor （VEGF） expression of ECV304 cells, and VEGF, angiopoietin-1 （Ang-1）, platelet-derived growth factor （PDGF） and fibroblast growth factor 2 （FGF2） expression of WI-38 ceils were assessed by 3-（4,5）-dimethylthiahiazo （-z-yl）-3,5-di-phenytetrazolitmaromide （MTT） assay, viable cell count- ing, flow cytometry （FCM）, and enzyme-linked immunosorbant assay （ELISA）. Results： We showed that the regenerated silk fibroin film was not cytotoxic to L929 cells and had no adverse influence on their adhesion, cell cycle or apoptosis; it had no adverse influence on the growth and VEGF secretion of ECV304 cells and no effect on the secretion of VEGF, Ang-1, PDGF and FGF2 by W1-38 cells. Conclusion： The regenerated silk fibroin film should be an excellent biomaterial with good cytocompatibility, providing a framework for reparation after trauma in clinical applications.
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