In fields like astronomy and radar technology, high-gain antennas are required for long-distance communication. Due to its relatively large gain, the use of parabolic antennas has become very popular over time, becaus...In fields like astronomy and radar technology, high-gain antennas are required for long-distance communication. Due to its relatively large gain, the use of parabolic antennas has become very popular over time, because they can easily achieve gains of above 30 dB at microwave and higher frequencies. Today, most systems’ success depends on how well the antennas perform. These antennas are available in different types and sizes. Each antenna’s effective area usually has less than the actual physical area of the antenna surface. This means that the unused area of the antenna is massive, and a waste. The aim of the research is to show that the actual physical aperture of a parabolic antenna can be reduced as much as possible to equal the effective area, as given by the antenna formula, thereby saving manufacturing costs, improve the aesthetics. In other words, the focus of this work is to experimentally show that reflector antenna can be made of smaller sizes but better performance. Measurements were taken from different positions from a parabolic antenna, the signal level measured and compared with signal levels for optimal performance.展开更多
Good translations play a very important role in cultural exchange.The idea of reception aesthetics think the reader as the center in translation process.This paper will study the translation of culture-loaded words fr...Good translations play a very important role in cultural exchange.The idea of reception aesthetics think the reader as the center in translation process.This paper will study the translation of culture-loaded words from the perspective of reception aesthetics.It is divided into five parts.The first part mainly introduces the background and theoretical foundation of this paper,the second part introduces the writer’s works,the third part gives examples to analyze the culture-loaded words appearing in The Golden Cangue,the fourth part gives examples of the translation methods,and the fifth part is the conclusion.It aims to provide a reference for the English translation of culture-loaded words.展开更多
The hypersonic boundary-layer receptivity to slow acoustic waves is investigated for the Mach 6 flow over a 5-degree half-angle blunt cone with the nose radius of 5.08 mm. The plane acoustic wave interacts with the bo...The hypersonic boundary-layer receptivity to slow acoustic waves is investigated for the Mach 6 flow over a 5-degree half-angle blunt cone with the nose radius of 5.08 mm. The plane acoustic wave interacts with the bow shock, and generates all types of disturbances behind the shock, which may take various routes to generate the boundarylayer unstable mode. In this paper, two routes of receptivity are investigated in detail.One is through the disturbance in the entropy layer. The other is through the slow acoustic wave transmitted downstream the bow shock, which can excite the boundary-layer mode due to the synchronization mechanism. The results show that, for a low frequency slow acoustic wave, the latter route plays a leading role. The entropy-layer instability wave is able to excite the first mode near the neutral point, but its receptivity efficiency is much lower.展开更多
The objective of receptivity is to investigate the mechanisms by which external disturbances generate unsta- ble waves. In hypersonic boundary layers, a new receptivity process is revealed, which is that fast and slow...The objective of receptivity is to investigate the mechanisms by which external disturbances generate unsta- ble waves. In hypersonic boundary layers, a new receptivity process is revealed, which is that fast and slow acoustics through nonlinear interaction can excite the second mode near the lower-branch of the second mode. They can generate a sum-frequency disturbance though nonlinear interaction, which can excite the second mode. This receptivity process is generated by the nonlinear interaction and the nonparal- lel nature of the boundary layer. The receptivity coefficient is sensitive to the wavenumber difference between the sumfrequency disturbance and the lower-branch second mode. When the wavenumber difference is zero, the receptivity coefficient is maximum. The receptivity coefficient decreases with the increase of the wavenumber difference. It is also found that the evolution of the sum-frequency disturbance grows linearly in the beginning. It indicates that the forced term generated by the sum-frequency disturbance resonates with the second mode.展开更多
Asymptotic method was adopted to obtain a receptivity model for a pipe Poiseuille flow under periodical pressure,the wall of the pipe with a bump.Bi_orthogonal eigen_function systems and Chebyshev collocation method w...Asymptotic method was adopted to obtain a receptivity model for a pipe Poiseuille flow under periodical pressure,the wall of the pipe with a bump.Bi_orthogonal eigen_function systems and Chebyshev collocation method were used to resolve the problem.Various spatial modes and the receptivity coefficients were obtained.The results show that different modes dominate the flow in different stages,which is comparable with the phenomena observed in experiments.展开更多
Endometrial receptivity is an important factor that influences embryo implantation.Thus,it is important to identify an applicable approach to improve endometrial receptivity in women undergoing assisted reproductive t...Endometrial receptivity is an important factor that influences embryo implantation.Thus,it is important to identify an applicable approach to improve endometrial receptivity in women undergoing assisted reproductive technology.Recently,growing evidence has indicated that intrauterine platelet-rich plasma(PRP)infusion is an effective method to obtain a satisfactory reproductive outcome by increasing endometrial thickness and improving endometrial receptivity.Therefore,the present review aims to outline the possible mechanisms of PRP on endometrial receptivity and summarize the present literature on the effects of PRP therapy in improving endometrial receptivity.展开更多
With the improvement of image editing technology,the threshold of image tampering technology decreases,which leads to a decrease in the authenticity of image content.This has also driven research on image forgery dete...With the improvement of image editing technology,the threshold of image tampering technology decreases,which leads to a decrease in the authenticity of image content.This has also driven research on image forgery detection techniques.In this paper,a U-Net with multiple sensory field feature extraction(MSCU-Net)for image forgery detection is proposed.The proposed MSCU-Net is an end-to-end image essential attribute segmentation network that can perform image forgery detection without any pre-processing or post-processing.MSCU-Net replaces the single-scale convolution module in the original network with an improved multiple perceptual field convolution module so that the decoder can synthesize the features of different perceptual fields use residual propagation and residual feedback to recall the input feature information and consolidate the input feature information to make the difference in image attributes between the untampered and tampered regions more obvious,and introduce the channel coordinate confusion attention mechanism(CCCA)in skip-connection to further improve the segmentation accuracy of the network.In this paper,extensive experiments are conducted on various mainstream datasets,and the results verify the effectiveness of the proposed method,which outperforms the state-of-the-art image forgery detection methods.展开更多
针对金属涂层缺陷图像分割中存在特征提取能力弱和分割精度低的问题,提出了一种改进的U^(2)-Net分割模型。首先,在U型残差块(RSU)中嵌入改进的增大感受野模块(receptive field block light,RFB_l),组成新的特征提取层,增强对细节特征的...针对金属涂层缺陷图像分割中存在特征提取能力弱和分割精度低的问题,提出了一种改进的U^(2)-Net分割模型。首先,在U型残差块(RSU)中嵌入改进的增大感受野模块(receptive field block light,RFB_l),组成新的特征提取层,增强对细节特征的学习能力,解决了网络由于感受野受限造成分割精度低的问题;其次,在U^(2)-Net分割模型的解码阶段引入有效的边缘增强注意力机制(contour enhanced attention,CEA),抑制网络中的冗余特征,获取具有详细位置信息的特征注意力图,增强了边界与背景信息的差异性,从而达到更精确的分割效果。实验结果表明,该模型在两个金属涂层剥落与腐蚀数据集上的平均交并比、准确率、查准率、召回率和F_1-measure分别达到80.36%、96.29%、87.43%、84.61%和86.00%,相比于常用的SegNet、U-Net以及U^(2)-Net分割网络的性能都有较大提升。展开更多
文摘In fields like astronomy and radar technology, high-gain antennas are required for long-distance communication. Due to its relatively large gain, the use of parabolic antennas has become very popular over time, because they can easily achieve gains of above 30 dB at microwave and higher frequencies. Today, most systems’ success depends on how well the antennas perform. These antennas are available in different types and sizes. Each antenna’s effective area usually has less than the actual physical area of the antenna surface. This means that the unused area of the antenna is massive, and a waste. The aim of the research is to show that the actual physical aperture of a parabolic antenna can be reduced as much as possible to equal the effective area, as given by the antenna formula, thereby saving manufacturing costs, improve the aesthetics. In other words, the focus of this work is to experimentally show that reflector antenna can be made of smaller sizes but better performance. Measurements were taken from different positions from a parabolic antenna, the signal level measured and compared with signal levels for optimal performance.
文摘Good translations play a very important role in cultural exchange.The idea of reception aesthetics think the reader as the center in translation process.This paper will study the translation of culture-loaded words from the perspective of reception aesthetics.It is divided into five parts.The first part mainly introduces the background and theoretical foundation of this paper,the second part introduces the writer’s works,the third part gives examples to analyze the culture-loaded words appearing in The Golden Cangue,the fourth part gives examples of the translation methods,and the fifth part is the conclusion.It aims to provide a reference for the English translation of culture-loaded words.
基金Project supported by the National Natural Science Foundation of China(Nos.11472188 and11332007)the National Key Research and Development Program of China(No.2016YFA0401200)
文摘The hypersonic boundary-layer receptivity to slow acoustic waves is investigated for the Mach 6 flow over a 5-degree half-angle blunt cone with the nose radius of 5.08 mm. The plane acoustic wave interacts with the bow shock, and generates all types of disturbances behind the shock, which may take various routes to generate the boundarylayer unstable mode. In this paper, two routes of receptivity are investigated in detail.One is through the disturbance in the entropy layer. The other is through the slow acoustic wave transmitted downstream the bow shock, which can excite the boundary-layer mode due to the synchronization mechanism. The results show that, for a low frequency slow acoustic wave, the latter route plays a leading role. The entropy-layer instability wave is able to excite the first mode near the neutral point, but its receptivity efficiency is much lower.
基金supported by the National Natural Science Foundation of China (Grants 11332007 and 11202147)the Specialized Research Fund for the Doctoral Program of Higher Education (Grants 20120032120007)
文摘The objective of receptivity is to investigate the mechanisms by which external disturbances generate unsta- ble waves. In hypersonic boundary layers, a new receptivity process is revealed, which is that fast and slow acoustics through nonlinear interaction can excite the second mode near the lower-branch of the second mode. They can generate a sum-frequency disturbance though nonlinear interaction, which can excite the second mode. This receptivity process is generated by the nonlinear interaction and the nonparal- lel nature of the boundary layer. The receptivity coefficient is sensitive to the wavenumber difference between the sumfrequency disturbance and the lower-branch second mode. When the wavenumber difference is zero, the receptivity coefficient is maximum. The receptivity coefficient decreases with the increase of the wavenumber difference. It is also found that the evolution of the sum-frequency disturbance grows linearly in the beginning. It indicates that the forced term generated by the sum-frequency disturbance resonates with the second mode.
文摘Asymptotic method was adopted to obtain a receptivity model for a pipe Poiseuille flow under periodical pressure,the wall of the pipe with a bump.Bi_orthogonal eigen_function systems and Chebyshev collocation method were used to resolve the problem.Various spatial modes and the receptivity coefficients were obtained.The results show that different modes dominate the flow in different stages,which is comparable with the phenomena observed in experiments.
基金the Guangdong Medical Science and Technology Research Foundation(No.A2021345).
文摘Endometrial receptivity is an important factor that influences embryo implantation.Thus,it is important to identify an applicable approach to improve endometrial receptivity in women undergoing assisted reproductive technology.Recently,growing evidence has indicated that intrauterine platelet-rich plasma(PRP)infusion is an effective method to obtain a satisfactory reproductive outcome by increasing endometrial thickness and improving endometrial receptivity.Therefore,the present review aims to outline the possible mechanisms of PRP on endometrial receptivity and summarize the present literature on the effects of PRP therapy in improving endometrial receptivity.
基金supported in part by the National Natural Science Foundation of China(Grant Number 61971078)Chongqing University of Technology Graduate Innovation Foundation(Grant Number gzlcx20222064).
文摘With the improvement of image editing technology,the threshold of image tampering technology decreases,which leads to a decrease in the authenticity of image content.This has also driven research on image forgery detection techniques.In this paper,a U-Net with multiple sensory field feature extraction(MSCU-Net)for image forgery detection is proposed.The proposed MSCU-Net is an end-to-end image essential attribute segmentation network that can perform image forgery detection without any pre-processing or post-processing.MSCU-Net replaces the single-scale convolution module in the original network with an improved multiple perceptual field convolution module so that the decoder can synthesize the features of different perceptual fields use residual propagation and residual feedback to recall the input feature information and consolidate the input feature information to make the difference in image attributes between the untampered and tampered regions more obvious,and introduce the channel coordinate confusion attention mechanism(CCCA)in skip-connection to further improve the segmentation accuracy of the network.In this paper,extensive experiments are conducted on various mainstream datasets,and the results verify the effectiveness of the proposed method,which outperforms the state-of-the-art image forgery detection methods.
