Enhancing mechanical properties of Mg-Gd-Y-Zn alloys via microalloying with Ce and La

Zhaobin Zhang,Jonghyun Kim,Hongxin Liao,김기범,최태집,이태경,FuSheng Pan 대한금속·재료학회 2022 대한금속·재료학회지 Vol.60 No.9

This study investigated the microstructure and mechanical properties of Mg-1Gd-1Y-1Zn (at.%) alloys containing designed amounts of Ce or La. The Mg5(Gd,Zn) phase formed in the as-cast Mg-Gd-Y-Zn- Ce/La alloys and disappeared after a homogenization treatment at 500°C for 24 h. The addition of Ce and La resulted in the formation of Ce(Mg,Zn)12 and La(Mg,Zn)12 phases, respectively. Except for that, the Ce or La addition had no significant effect on the morphology, volume fraction, and type of the long-period stacking ordered (LPSO) phases in the Mg-Gd-Y-Zn alloy. The grain size decreased with increasing microalloying content because the heavy Ce and La atoms impeded atomic migration across the boundaries. The solute drag effect led to the formation of the rare earth texture in the extruded Mg-Gd-Y-Zn-Ce/La alloys, whose extent decreased with increasing microalloying content. The mechanical strength was improved by the addition of Ce or La at the sacrifice of ductility. In particular, La exhibited a stronger reinforcement ability than Ce when it was added to the Mg-Gd-Y-Zn alloys. Among the investigated chemical compositions, the Mg-1Gd-1Y-1Zn- 0.3La alloy exhibited the highest strength because it had the finest grains, the highest volume fraction of the second phase, and the weakest texture intensity. Furthermore, the alloys showed an unusual yield asymmetry due to the difference in the deformation mode of the LPSO phase.

Security Cooperation Model Based on Topology Control and Time Synchronization for Wireless Sensor Networks

Zhaobin Liu,Wenzhi Liu,Qiang Ma,Gang Liu,Liang Zhang,Ligang Fang,Victor S. Sheng 한국통신학회 2019 Journal of communications and networks Vol.21 No.5

To address malicious attacks generated from wirelesssensor networks (WSNs), in this paper, we study the difficulty ofdetecting uncoordinated behavior by using a model that is unreliableand has uncontrollable accuracy, trustless control, and an inextensibleprotocol. A security collaboration model involving coupledstate vectors associated with topology control and time synchronizationis proposed. The networks achieve synchronizationusing weights and by controlling the number of goals. The simplecalculation of time synchronization values between neighboringnodes serves as the basis for judging the behavior of the nodetopology control. The coupling state vector calculation is the coreof the model. The topology coupling strength rate, signal intensityreduction, clock drift, and clock delay are combined to form a comprehensivemodel. The network energy consumption is reduced byupdating the coupling state vector regularly. The coupling cooperationthreshold is set to make security decisions and effectivelydistinguish between attack nodes and dead nodes. Thus, to ensurethe security and reliability of the network, we present a securitycooperation collection tree protocol (SC-CTP) scheme that maintainsa trusted environment and isolates misbehaving nodes. Thesimulation results show that the model can detect malicious nodeseffectively, has a high detection rate, and greatly reduces the energyconsumption of the whole network. In order to verify the effectivenessof the proposed model, a large-scale wireless sensor networkwith 200 nodes was deployed on a campus. The proposed modelwas applied to optimize the deployment of key nodes on the campus. Furthermore, a candidate set of these nodes were selected toachieve coupling cooperation of key goals. This test verified the reliabilityof the model, its customizable accuracy, and the reliabilityof the control.

Multi-focus Image Fusion Based on Random Walk

Wang Zhaobin,Wang Ziye,Cui Zijing,Chen Lina,Zhang Yaonan 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.6

An effective multi-focus image fusion algorithm based on random walk is proposed in this paper. Random walk and guided filter have attracted extensive attention in image fusion. Random walk is usually used to solve probability problems and it has a good smoothing effect, and guided filter can preserve the gradient information of the image well. The combination of two algorithms can better retain the edge information of the input image. Six sets of source images and five existing methods are used in the experiment and the experimental results show that the proposed algorithm outperforms the existing methods in both subjective and objective evaluation.

Effects of Daidzein on Body Weight Gain, Serum IGF-I Level and Cellular Immune Function in Intact Male Piglets

Wang, Genlin,Zhang, Xiangying,Han, Zhaoyu,Liu, Zhaobin,Liu, Weirong Asian Australasian Association of Animal Productio 2002 Animal Bioscience Vol.15 No.7

10 male piglets at 5-6 weeks old with similar body weight (BW) were randomly assigned into the experimental (EXP) and control (CON) groups. The animals in EXP received intro-muscular injection with daidzein (DA) at the dose of 0.5 mg DA per kg start BW on day 1. The same procedures were repeated once every 3 days for eight times. The animals in CON received the injection only with same volume of control peanut oil. The animals were weighted on day 14 and 28 and the blood samples were obtained at different stages of the treatment for determining IGF-I levels and blood parameters. At the end of the experiment, the thymus and spleen from all the animals were surgically taken out and weighted. The results showed that BW and average daily gain (ADG) were not significantly different between the groups in term of the whole period, but ADG between days 14-28 was higher in EXP than in CON (p<0.05). On days 18, 21 and 25, IGF-I levels in EXP group were 20.53% (p<0.05), 15.92% (p>0.05) and 23.46% (p<0.05), respectively, higher than those in CON. The weights of thymus and spleen, the ratios of their weights to BW and red blood count (RBC) did not significantly differ between the groups at all stages. White blood count (WBC) in EXP steadily increased from day 22, reached its apex on day 24, which was higher than in CON (p<0.05) and its own levels on day 20 and 22 (p<0.01 or p<0.05), and remained higher on the later time (p=0.058). The results of percentage of T-Lymphocytes also demonstrated similar trend to WBC, but TLymphocyte transformation rate (%) appeared no significant change between the groups. In conclusion, Daidzein could stimulate male piglet growth and elevate serum IGF-I levels at certain stages of the treatment. It could also increase WBC and T-Lymphocyte rates, but had no significant impacts on RBC and T-Lymphocyte transformation rate.

Effect on Zn on Microstructures and Mechanical Properties of Mg–Gd–Y–Zn LPSO Alloys

Jonghyun Kim,Hongxin Liao,Xiang Ou,Zhaobin Zhang,Kaikai Kang,Taekyung Lee,Fusheng Pan 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11

In this study, the microstructures and mechanical properties of Mg–1Gd–1Y–xZn alloys (x = 0.2, 0.4, 0.6, and 0.8) wereinvestigated. Microstructural evolution was tracked during the process of casting, homogenization, and extrusion. Long-periodstacking-ordered (LPSO) and β phases were formed in the as-cast alloys. The volume fraction of the LPSO phase increasedwith increasing Zn content, whereas that of the β phase decreased. Although the homogenization dissolved the β phase intothe Mg matrix, there was no significant change in the volume fraction of the LPSO phases. Increasing the Zn content led toa slight reduction in grain size and a simultaneous strengthening of texture. The Mg–1Gd–1Y–0.2Zn alloy possessed a highdensity of fine LPSO phases and excellent reinforcement capacity, thereby exhibiting excellent mechanical properties atroom temperature. In addition, the low volume fraction of the LPSO phases in this alloy led to suppressed yield asymmetry.

Designs and Simulations of Multi-factor in Trust Evaluation

Zhao Bin,He Jingsha,Huang Na,Zhang Yixuan,Zhou Shiyi,Ji Jie 보안공학연구지원센터 2015 International Journal of Database Theory and Appli Vol.8 No.1

Trust Model is an efficient way of resolving the trust problems in open networks in which trust evaluation is a key issue to be addressed in trust management. According to the design rules of trust models, the problem of the lack of dynamic adapt ability in trust evaluating, the lack of effective aggregation of trust and the lack of considerations to incentive mechanisms and so on, this paper introduced the bonus-penalty factor which shows how reliable is the direct trust of the recommend entities to the subject and evaluation reliability of the recommend entities which is used to decide whether the access object would adopt the recommendation of the recommend entities during the calculation of the recommend trust. The measurement of integrated trust solves the weight problem between direct trust and recommendatory trust by introducing balanced weight factor. Finally, we present designs of bonus-penalty function and balanced weight factor and simulations by Matlab software.