Novel Water-Air Circulation Quenching Process for AISI 4140 Steel

Liyun Zheng,Dawei Zheng1,Lixin Zhao,Lihui Wang,Kai Zhang 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.6

AISI 4140 steel is usually used after quenching and tempering. During the heat treatment process in industry production, there are some problems, such as quenching cracks, related to water-cooling and low hardness due to oil quenching. A water-air circulation quenching process can solve the problems of quenching cracks with water and the high cost quenching with oil, which is flammable, unsafe and not enough to obtain the required hardness. The control of the water-cooling and air-cooling time is a key factor in the process. This paper focuses on the quenching temperature, water-air cycle time and cycle index to prevent cracking for AISI 4140 steel. The optimum heat treatment parameters to achieve a good match of the strength and toughness of AISI 4140 steel were obtained by repeated adjustment of the water-air circulation quenching process parameters. The tensile strength, Charpy impact energy at -10 °C and hardness of the heat treated AISI 4140 steel after quenching and tempering were approximately 1098 MPa, 67.5 J and 316 HB, respectively.

A Novel Resource Allocation Algorithm in Multi-media Heterogeneous Cognitive OFDM System

( Dawei Sun ),( Baoyu Zheng ) 한국인터넷정보학회 2010 KSII Transactions on Internet and Information Syst Vol.4 No.5

An important issue of supporting multi-users with diverse quality-of-service (QoS) requirements over wireless networks is how to optimize the systematic scheduling by intelligently utilizing the available network resource while, at the same time, to meet each communication service QoS requirement. In this work, we study the problem of a variety of communication services over multi-media heterogeneous cognitive OFDM system. We first divide the communication services into two parts. Multimedia applications such as broadband voice transmission and real-time video streaming are very delay-sensitive (DS) and need guaranteed throughput. On the other side, services like file transmission and email service are relatively delay tolerant (DT) so varying-rate transmission is acceptable. Then, we formulate the scheduling as a convex optimization problem, and propose low complexity distributed solutions by jointly considering channel assignment, bit allocation, and power allocation. Unlike prior works that do not care computational complexity. Furthermore, we propose the FAASA (Fairness Assured Adaptive Sub-carrier Allocation) algorithm for both DS and DT users, which is a dynamic sub-carrier allocation algorithm in order to maximize throughput while taking into account fairness. We provide extensive simulation results which demonstrate the effectiveness of our proposed schemes.

Astragalin reduces lipopolysaccharide-induced acute lung injury in rats via induction of heme oxygenase-1

Donghua Zheng,Dawei Liu,Na Liu,Yukun Kuang,Qiang Tai 대한약학회 2019 Archives of Pharmacal Research Vol.42 No.8

Astragalin, a bioactive component of medicinalplants such as Rosa agrestis, has anti-inflammatory andantioxidant features. Induction of heme oxygenase (HO)-1is an effective strategy to reduce excessive generated oxidantsduring the pathogenesis of acute lung injury (ALI). The aim of the present study is to investigate that whetherthe anti-inflammatory and antioxidant features of astragalinis HO-1 dependent in lipopolysaccharide (LPS)-inducedALI. Sprague–Dawley rats were used in animal study. Intratracheal LPS was performed to induce experimentalALI model. Astragalin was administrated 1 h after LPSchallenge. Human lung epithelial cells were used in cellstudy. Samples from rats were harvested at 24 h post LPSchallenge. Astragalin treatment inhibited LPS-inducedinflammatory cells infiltration in the lung and pulmonaryedema. Astragalin treatment markedly enhanced theactivity of HO-1 compared with vehicle-treated group at24 h post LPS challenge. Levels of lipid hydroperoxide, amarker for oxidative stress, were decreased in astragalintreatedanimals compared with vehicle-treated group. However, the protective effect of astragalin on LPS-inducedALI was abolished in an inhibitor of HO-1-treatedanimals. Moreover, the astragalin-induced the upregulationof HO-1 in human lung epithelial cells was inhibited whennuclear factor erythroid-2-related factor 2 (Nrf2) wassilenced by small interfering RNA. Astragalin reducesLPS-induced ALI via activation of Nrf2/HO-1 pathway.

Application of T-S Fuzzy Neural Network to Pattern Recognition of Corona Discharge

Dianchun Zheng,Renxu Yang,Chuntian Chen,Dawei Zhao,Jiaxiang Yang 보안공학연구지원센터(IJSIP) 2014 International Journal of Signal Processing, Image Vol.7 No.1

Numerical simulation of the sheet/cloud cavitation around a two-dimensional hydrofoil using a modified URANS approach

Zhong Li,Dawei Zheng,Feng Hong,Dan Ni 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.1

Cavitating flow over a two-dimensional Clark-Y hydrofoil is numerically investigated via a Modified density correction method (MDCM) for turbulence closure to improve the capability of two-phase flow simulation for the k-ε RNG turbulence model. A transport equation model for the local volume fraction of vapor is solved, and a modified version of the Kunz model is used for the condensation and evaporation processes. Simulations have been conducted for various cavitation numbers ranging from non-cavitating to cloud cavitation. We compared the time-averaged lift and drag coefficients, cavitation dynamics, and time-averaged velocity profiles with the available experimental data for the MDCM and Density correction method (DCM). The comparisons between numerical and experimental results show that the MDCM and DCM are capable of capturing the special trends of the lift coefficient at the inception cavitation stage and the drag coefficient at the cloud cavitation stage. The MDCM is more robust and physical than the DCM in predicting the wake flow downstream from the trailing edge. The predicted attached cavities of both models almost show the same trend near the leading edge of the hydrofoil. However, the MDCM predicts more shedding cavity than the DCM in the wake region.

Effects of Intercropping on Soil Nutrients and Enzyme Activities in Continuous Taro Cropping Fields

Hanlin Zhang,Xianqing Zheng,Yifei Wang,Ke Song,Shuangxi Li,Juanqin Zhang,Qiyong He,Dawei Yuan,Weiguang Lv 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Turbulent-image Restoration Based on a Compound Multibranch Feature Fusion Network

Banglian Xu,Yao Fang,Leihong Zhang,Dawei Zhang,Lulu Zheng Optical Society of Korea 2023 Current Optics and Photonics Vol.7 No.3

In middle- and long-distance imaging systems, due to the atmospheric turbulence caused by temperature, wind speed, humidity, and so on, light waves propagating in the air are distorted, resulting in image-quality degradation such as geometric deformation and fuzziness. In remote sensing, astronomical observation, and traffic monitoring, image information loss due to degradation causes huge losses, so effective restoration of degraded images is very important. To restore images degraded by atmospheric turbulence, an image-restoration method based on improved compound multibranch feature fusion (CMFNetPro) was proposed. Based on the CMFNet network, an efficient channel-attention mechanism was used to replace the channel-attention mechanism to improve image quality and network efficiency. In the experiment, two-dimensional random distortion vector fields were used to construct two turbulent datasets with different degrees of distortion, based on the Google Landmarks Dataset v2 dataset. The experimental results showed that compared to the CMFNet, DeblurGAN-v2, and MIMO-UNet models, the proposed CMFNetPro network achieves better performance in both quality and training cost of turbulent-image restoration. In the mixed training, CMFNetPro was 1.2391 dB (weak turbulence), 0.8602 dB (strong turbulence) respectively higher in terms of peak signal-to-noise ratio and 0.0015 (weak turbulence), 0.0136 (strong turbulence) respectively higher in terms of structure similarity compared to CMFNet. CMFNetPro was 14.4 hours faster compared to the CMFNet. This provides a feasible scheme for turbulent-image restoration based on deep learning.