Approach for Decoupling the Non-Linear Cross-Talk in a Six-Dimensional Force Platform

Zhiyong Mao,Ping Cai,Dian Wang,Rui Ji 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.3

As the primary equipment for balance function assessment, the six-dimensional force platform (SDFP) should maintain its quality for long term use. Unfortunately the inevitable cross-talk will deteriorate its comprehensive performance. Obtaininga new sensitivity coefficient matrix through re-calibration is an effective way to guarantee the measurement accuracy. Generalized force loading can be used for in-situ calibration, but the calibration result depends on the selected set of loading point when the components are nonlinearly coupled.This study attempts to find an appropriate loading point set to obtain the optimal decoupling matrix for the SDFP when non-linearcoupling exists. The decoupling design of strain gauge layout and the non-linear coupling resulting from the bending deformation of the top plate are analyzed. Based on the analysis, a digital simulation is conducted to investigate the relationship between the decoupling performance and the selection of the loading points. The simulation results show that the center distance of the loading point is the primary factor affecting the decoupling performance. An in-situ calibration is conducted, and the orthogonal test rule is used to evaluate the performance of the system. A comparison of the results shows that the experimental results agree with those of the simulations.

Study on Semi-Solid A380 Aluminum Alloy Slurry Prepared by Water-Cooling Serpentine Channel and Its Rheo-Diecasting

Zhiyong Liu,Weimin Mao,Tan Wan,Guotao Cui,Weipan Wang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

The semi-solid A380 aluminum alloy slurry prepared by water-cooling serpentine channel and its rheo-diecasting werestudied in this paper. The result showed that the pouring temperature and cooling water fow rate had a signifcant efect onthe semi-solid slurry. When the pouring temperature decreased from 670 to 610 °C, the average grain diameter and shapefactor of the primary α-Al grains decreased from 64 to 47 µm and increased from 0.74 to 0.82, respectively, but the mass ofsemi-solid slurry blocked in channel increased. With the cooling water fow rate increasing from 0 to 1000 L/h, the semisolid slurry frstly got optimized and then deteriorated. Under the condition of the same die casting process parameters, therheo-diecastings produced by the semi-solid slurry prepared through water-cooled serpentine channel had higher mechanicalproperties than those of the traditional die castings.

Study on Formation of Microstructure in Rheo-Diecastings of Semi-Solid A380 Aluminum Alloy Slurry

Zhiyong Liu,Guotao Cui,Tan Wan,Weimin Mao 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

The formation of the microstructure in the rheo-diecastings were studied by the experiment of rheo-diecasting with semi-solidA380 Aluminum alloy slurry. The results show that the grain diameter and shape factor of primary α-Al grains decreased andincreased along the rheo-diecasting direction, respectively, making the primary α-Al grains gradually distributing uniformly. The combination of injection pressure and narrow gate of the runner and ingate was the main reason for the evolution of theprimary α-Al grains, moreover, the collision and friction among primary α-Al grains during the flling were helpful for therefnement and spheroidization of the primary α-Al grains. The residual liquid solidifed into the secondary solidifcationmicrostructure accompanied by the evolution of the primary α-Al grains. The accumulation of the fragments of the primaryα-Al grains, the secondary α2-Al nuclei or grains which formed in previous positions, the efective nucleation rate of theresidual liquid, and the collision and fraction among the secondary α2-Al grains and between the secondary α2-Al grainand the primary α-Al grains made the secondary solidifcation microstructure of the residual liquid present multiplex andcomplicate characteristics.

Ground effects on wind-induced responses of a closed box girder

Mao, Wenhao,Zhou, Zhiyong Techno-Press 2017 Wind and Structures, An International Journal (WAS Vol.25 No.4

When bridges are constructed with lower heights from the ground, the formed channel between the deck and the ground will inevitably hinder or accelerate the air flow. This in turn will have an impact on the aerodynamic forces on the deck, which may result in unexpected wind-induced responses of bridges. This phenomenon can be referred to "ground effects." So far, no systematic studies into ground effects on the wind-induced responses of closed box girders have been performed. In this paper, wind tunnel tests have been adopted to study the ground effects on the aerodynamic force coefficients and the wind-induced responses of a closed box girder. In correlation with the heights from the ground in two ground roughness, the aerodynamic force coefficients, the Strouhal number ($S_t$), the vortex-induced vibration (VIV) lock-in phenomena over a range of wind velocities, the VIV maximum amplitudes, the system torsional damping ratio, the flutter derivatives, the critical flutter wind speeds and their variation laws correlated with the heights from the ground of a closed box girder have been presented through wind tunnel tests. The outcomes show that the ground effects make the vortex-induced phenomena occur in advance and adversely affect the flutter stability.

Ground Effects on the Vortex-induced Vibration of Bridge Decks

Wenhao Mao,Zhiyong Zhou,Ai Huilin 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.3

The present study investigated the ground effects on the VIV of a closed box girder based on wind tunnel tests and numerical methods. First, we presented a vibration measurement system for wind-tunnel test to simulate ground effects on the bridge girder. Second, we investigated the Strouhal number (St), the VIV lock-in phenomena over a range of wind velocities, and the maximum VIV amplitudes and their change laws in correlation with the height from the ground in two different ground conditions. The outcomes showed the following: that a low height from the ground can lead to high St numbers; that ground effects did not change the width of VIV lock-in range, but did impel VIVs to occur earlier in the uniform flow field; and that the maximum VIV amplitudes was reduced and the VIV lock-in range narrowed in the turbulent flow field. Finally, we conducted the numerical simulation method to study the ground effect mechanism on VIVs. The numerical results showed that the periodic vortex shedding will generate periodic forces on the structure, which leads to the occurrence of VIVs. Ground effects can speed up vortex shifting, whereas aerodynamic forces on the deck are weakened.

Multi-classification Sensitive Image Detection Method Based on Lightweight Convolutional Neural Network

( Yueheng Mao ),( Bin Song ),( Zhiyong Zhang ),( Wenhou Yang ),( Yu Lan ) 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.5

In recent years, the rapid development of social networks has led to a rapid increase in the amount of information available on the Internet, which contains a large amount of sensitive information related to pornography, politics, and terrorism. In the aspect of sensitive image detection, the existing machine learning algorithms are confronted with problems such as large model size, long training time, and slow detection speed when auditing and supervising. In order to detect sensitive images more accurately and quickly, this paper proposes a multi-classification sensitive image detection method based on lightweight Convolutional Neural Network. On the basis of the EfficientNet model, this method combines the Ghost Module idea of the GhostNet model and adds the SE channel attention mechanism in the Ghost Module for feature extraction training. The experimental results on the sensitive image data set constructed in this paper show that the accuracy of the proposed method in sensitive information detection is 94.46% higher than that of the similar methods. Then, the model is pruned through an ablation experiment, and the activation function is replaced by Hard-Swish, which reduces the parameters of the original model by 54.67%. Under the condition of ensuring accuracy, the detection time of a single image is reduced from 8.88ms to 6.37ms. The results of the experiment demonstrate that the method put forward has successfully enhanced the precision of identifying multi-class sensitive images, significantly decreased the number of parameters in the model, and achieved higher accuracy than comparable algorithms while using a more lightweight model design.

Fluoxetine Protects against Big Endothelin-1 Induced Anti-Apoptosis by Rescuing Kv1.5 Channels in Human Pulmonary Arterial Smooth Muscle Cells

FeiFeng Dai,ZhiFu Mao,Jun Xia,ShaoPing Zhu,ZhiYong Wu 연세대학교의과대학 2012 Yonsei medical journal Vol.53 No.4

Purpose: Pulmonary Kv channels are thought to play a crucial role in the regulation of cell proliferation and apoptosis. Previous studies have shown that fluoxetine upregulated the expression of Kv1.5 and prevented pulmonary arterial hypertension in monocrotaline-induced or hypoxia-induced rats and mice. The current study was designed to test how fluoxetine regulates Kv1.5 channels, subsequently promoting apoptosis in human PASMCs cultured in vitro. Materials and Methods: Human PASMCs were incubated with low-serum DMEM, ET-1, and fluoxetine with and without ET-1 separately for 72 h. Then the proliferation, apoptosis, and expression of TRPC1 and Kv1.5 were detected. Results: In the ET-1 induced group, the upregulation of TRPC1 and down regulation of Kv1.5 enhanced proliferation and anti-apoptosis,which was reversed when treated with fluoxetine. The decreased expression of TRPC1 increased the expression of Kv1.5, subsequently inhibiting proliferation while promoting apoptosis. Conclusion: The results from the present study suggested that fluoxetine protects against big endothelin-1 induced anti-apoptosis and rescues Kv1.5 channels in human pulmonary arterial smooth muscle cells, potentially by decreasing intracellular concentrations of Ca2+.

A Triple Residual Multiscale Fully Convolutional Network Model for Multimodal Infant Brain MRI Segmentation

( Yunjie Chen ),( Yuhang Qin ),( Zilong Jin ),( Zhiyong Fan ),( Mao Cai ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.3

The accurate segmentation of infant brain MR image into white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF) is very important for early studying of brain growing patterns and morphological changes in neurodevelopmental disorders. Because of inherent myelination and maturation process, the WM and GM of babies (between 6 and 9 months of age) exhibit similar intensity levels in both T1-weighted (T1w) and T2-weighted (T2w) MR images in the isointense phase, which makes brain tissue segmentation very difficult. We propose a deep network architecture based on U-Net, called Triple Residual Multiscale Fully Convolutional Network (TRMFCN), whose structure exists three gates of input and inserts two blocks: residual multiscale block and concatenate block. We solved some difficulties and completed the segmentation task with the model. Our model outperforms the U-Net and some cutting-edge deep networks based on U-Net in evaluation of WM, GM and CSF. The data set we used for training and testing comes from iSeg-2017 challenge (http://iseg2017.web.unc.edu).