Hot Deformation Characteristics and Processing Map Analysis of Pre-Forged AZ80 Magnesium Alloy

Shi‑quan Huang,Ming Lu,Sheng‑lan Luo,Hai‑lin He,You‑ping Yi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

The hot deformation behavior of pre-forged AZ80 magnesium alloy is investigated by the isothermal compression tests attemperatures of 523–683 K and strain rates of 0.0001–0.1 s−1, and analyzed by the processing maps for guiding isothermaldie forging. Flow localization and even cracking occurs at low temperatures and high strain rates, where shear deformationdegree shows a positive correlation with the ��( ̇�� ) value. Two stability regions with high efficiency is found out by theprocessing maps. At common stability region with high temperatures and low strain rates, peak power dissipation efficiencydoes not represent optimum deformation condition as reported in other materials. A Z parameter criterion is introduced forparameters optimization. javascript:void(0); a new stability domain of 523–590 K and 0.0001–0.01 s−1 is observed, which istypical for fine microstructure composed of equiaxed clean α-Mg grains and big particles both about 1 μm (573 K/0.01 s−1).Super plasticity is speculated to occur at that condition.

Sliding Mode Control for Continuous Casting Mold Oscillatory System Driven by Servo Motor

Sheng-Li Shi,Ke-song Kang,Jian-Xiong Li,Yi-ming Fang 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.4

This paper develops an extended-state-observer-based sliding mode control strategy for continuous castingmold oscillatory system driven by servo motor in the presence of matched and mismatched disturbance. Extendedstate observers are employed to estimate the compound disturbances, and the requirement of the derivativeof the compound disturbances to zero is avoided. In order to counteract the mismatched disturbance and attenuatethe chattering phenomenon, a novel sliding surface based on extended state observer is designed for the system. Simulation results illustrate that the proposed controller can achieve better tracking performance and robustness tothe compound disturbance.

Creep Constitutive Model for Frozen Soils Based on Hardening and Damage Effects

Sheng Shi,Feng Zhang,Decheng Feng,Kangwei Tang 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.4

The creep characteristics of frozen soil has significant influences on infrastructure stability in cold regions. It is important for frozen ground engineering to describe the creep properties of frozen soil with accurate models. In this research, a new structure creep model is developed by considering the hardening factor and damage factor which play different roles during various creep stages. According to the experimental results under different stress levels, the proposed model was verified. The calculation results exhibit the proposed model has abilities to predict the creep characteristics of frozen soils, especially the nonlinear stress-strain behavior at acceleration creep stage.

Fractional-disturbance-observer-based Sliding Mode Control for Fractional Order System with Matched and Mismatched Disturbances

Sheng-Li Shi,Jian-Xiong Li,Yi-ming Fang 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.5

This paper addresses the sliding mode control for a class of fractional order systems with matched andmismatched disturbances. Firstly, fractional disturbance observer is presented to estimate both the matched andmismatched disturbances, and the boundedness of the estimation error can be guaranteed. Secondly, sliding modesurface is constructed based on the output of the observer. The bounded stability of the closed-loop system underthe designed controller is revealed by theoretical analysis. Finally, simulation results show that the proposed controlstrategy can effectively suppress the effect of the matched and mismatched disturbances on the system.

창의적 디자인교육을 위한 교육환경 개선방안 - 대학교 학습공간을 중심으로 -

사춘생 ( Shi Chun-sheng ),김면 ( Kim Myoun ) 커뮤니케이션디자인학회(구 시각디자인학회) 2019 커뮤니케이션 디자인학연구 Vol.67 No.-

21세기 글로벌 환경 속에서 경쟁하고 성장할 수 있는 국가의 역량은 복합적인 문제해결 능력을 갖춘 창의적 인재의 양성에 달려있다. 따라서 한국대학의 경우 창조경제 창출에 기여가 가능한 혁신 능력을 갖춘 고급 인력의 양성을 지향하는 다양한 창의적 혁신 교육 패러다임의 필요성이 대두되고 있으며 다학제 교육이 많은 관심을 받으면서 의미의 확장 및 학제간 용합에 기반을 둔 다양한 교육프로그램 개발에 대한 지원이 이루어지고 있다. 교육에서 중요한 역할을 하고 있는 교육공간은 창의성 촉진에 영향을 미치며 간과해서는 안될 충분히 가치 있는 요인임을 시사한다. 따라서 혁신교육은 학습과정에 적용되어 현재와는 완전히 다른 모습으로 교육이 진행되기 때문에 교수 - 학습방법 개발과 더불어 창의적인 교육공간 측면의 접근이 체계적이고 실질적인 연구가 필요하다. 본 연구도 창의적 인재의 양성을 위해 학교의 전반적인 분위기를 좌우하는 학교 내의 물리적 환경을 어떻게 조성할 수 있을 것인가에 대한 연구의 초점을 두고자 하였다. 이를 위해 세계에서 가장 창의적 교육환경을 가진 두 학교의 확장된 교수 - 학습활동의 기능적 측면에서 분석을 통해 다학제 교육이 가지고 있는 교수-학습방법과 다학제 교육 공간 시스템이 가져야하는 속성(Attribute)을 다음과 같이 발견하였다. 1. 학습공간의 변화는 반드시 그 공간에서 일어날 교수 - 학습방법 & 활동에 관한 교육내용을 기반으로 기획되며 다양한 형태와 기능의 공간으로 변화가 가능해야 된다. 2. 학교가 추구하는 비전과 가치들을 정립하는 작업이 선행되어야 하며, 그 과정이 다양하고 개방적이며 독립적인 공간으로 이루어질 수 있도록 구성되어야 한다. 3. 공간 재구성 과정에서 학생 수를 적절히 조절하여 사용자에게 자유로운 활동공간을 제공함으로써 창의적 사고 증진을 촉진시킨다. 이를 바탕으로 창의적 다학제 공간 조성시 고려해야 할 구체적인 공간계획 방향은 무엇인지 탐색하고자 한다. 사례를 분석해봄으로써 새로운 교육 패러다임에 맞는 다학제 공간을 구축하거나 또는 기존의 공간을 재구성하는 데에 참고자료로 활용이 가능하다는 데에 그 의미가 있다. A country's competence to compete and grow in the 21st global environment depends on creative talents. Therefore, universities in Korea put importance on the necessity of various creative innovation education paradigms to foster high-quality human resources equipped with innovative ability to contribute to creating creative economy. As the interest in multidisciplinary education increases, there are supports on the development of various education programs based on the expansion of meaning and inter-disciplinary integration. The educational space, which plays an important role in education, affects the stimulation of creativity and is a valuable element enough not to be ignored. Therefore, there is a need for research that creative educational space aspect is systemic and practical along with the development of teaching-learning method because innovation education is applied to learning process and is done in totally different ways from the present. However, the learning space research is changing very slowly compared to the change of digital technology and the change of education system. This study is intended to focus on how physical environment that influences the overall atmosphere of school can be established for nurturing creative talents. For this, two universities that have the most creative educational environment in the world are analyzed in the functional aspect of the extended teaching-learning activity, the teaching-learning methods of multidisciplinary education and the attributes of the multidisciplinary education space system should have are as the following: 1. The change in the learning space must be planned based on the teaching content concerning the teaching methods and activities that will take place in the space, and it should be possible to change into a space of various forms and functions. 2.The work of establishing the vision and values pursued by schools should be preceded, and be organized so that the process can be made into a diverse, open and independent space. 3. In the process of space reconstruction, the number of students is properly adjusted, thus providing the user with a free and active space to promote creative thinking. and based on the above, specific direction of space plan that should be considered in establishing creative multidisciplinary education space is sought. The significance of this study is that it can be used as a reference material for the establishment of multidisciplinary space suitable for new education paradigm and for the reorganization of existing space through the analysis of cases.

Mortality Characteristics and Prediction of Female Breast Cancer in China from 1991 to 2011

Shi, Xiao-Jun,Au, William W.,Wu, Ku-Sheng,Chen, Lin-Xiang,Lin, Kun Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.6

Aims: To analyze time-dependent changes in female breast cancer (BC) mortality in China, forecast the trend in the ensuing 5 years, and provide recommendations for prevention and management. Materials and Methods: Mortality data of breast cancer in China from 1991 to 2011 was used to describe characteristics and distribution, such as the changes of the standardized mortality rate, urban-rural differences and age differences. Trend-surface analysis was used to study the geographical distribution of mortality. In addition, curve estimation, time series modeling, Gray modeling (GM) and joinpoint regression were performed to estimate and predict future trends. Results: In China, the mortality rate of breast cancer has increased yearly since 1991. In addition, our data predicted that the trend will continue to increase in the ensuing 5 years. Rates in urban areas are higher than those in rural areas. Over the past decade, all peak ages for death by breast cancer have been delayed, with the first death peak occurring at 55 to 65 years of age in urban and rural areas. Geographical analysis indicated that mortality rates increased from Southwest to Northeast and from West to East. Conclusions: The standardized mortality rate of breast cancer in China is rising and the upward trend is predicted to continue for the next 5 years. Since this can cause an enormous health impact in China, much better prevention and management of breast cancer is needed. Consequently, disease control centers in China should place more focus on the northeastern, eastern and southeastern parts of China for breast cancer prevention and management, and the key population should be among women between ages 55 to 65, especially those in urban communities.

Highly Ordered Mesoporous Crystalline MoSe₂ Material with Efficient Visible‐Light‐Driven Photocatalytic Activity and Enhanced Lithium Storage Performance

Shi, Yifeng,Hua, Chunxiu,Li, Bin,Fang, Xiangpeng,Yao, Chaohua,Zhang, Yichi,Hu, Yong‐,Sheng,Wang, Zhaoxiang,Chen, Liquan,Zhao, Dongyuan,Stucky, Galen D. WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.14

<P><B>Abstract</B></P><P>Highly ordered mesoporous crystalline MoSe<SUB>2</SUB> is synthesized using mesoporous silica SBA‐15 as a hard template via a nanocasting strategy. Selenium powder and phosphomolybdic acid (H<SUB>3</SUB>PMo<SUB>12</SUB>O<SUB>40</SUB>) are used as Se and Mo sources, respectively. The obtained products have a highly ordered hexagonal mesostructure and a rod‐like particle morphology, analogous to the mother template SBA‐15. The UV‐vis‐NIR spectrum of the material shows a strong light absorption throughout the entire visible wavelength region. The direct bandgap is estimated to be 1.37 eV. The high surface area MoSe<SUB>2</SUB> mesostructure shows remarkable photocatalytic activity for the degradation of rhodamine B, a model organic dye, in aqueous solution under visible light irradiation. In addition, the synthesized mesoporous MoSe<SUB>2</SUB> possess a reversible lithium storage capacity of 630 mAh g<SUP>−1</SUP> for at least 35 cycles without any notable decrease. The rate performance of mesoporous MoSe<SUB>2</SUB> is much better than that of analogously synthesized mesoporous MoS<SUB>2</SUB>, making it a promising anode for the lithium ion battery.</P>

Effects of moderate pressure on premeability and viability of Saccharomyces cerevisiae cells

Shi-Ru Jia,Na-Chen,Yu-Jie Dai,Chang-Sheng Qiao,Jian-Dong Cui,Bo-Ning Liu 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3

With CO2 and N2 as the pressure media, the effects of the moderate pressure (0.1-1.0MPa) and the holding time on the conductivities of the cell suspension of Saccharomyces cerevisiae CICC1447 and Saccharomyces cerevisiae CICC1339, as well as the absorbances of the supernatant (after centrifuged) at 280 nm (A280) and 260 nm (A260) were determined. The membrane permeability of Saccharomyces cerevisiae CICC1447 increased significantly and the cell leakage was aggravated with the pressure increase. For Saccharomyces cerevisiae CICC1339, the conductivity of the cell suspension, A280 and A260 of the supernatant fluctuated with the pressure increase; as a whole, they increased with pressure. Different from high pressure, a moderate pressure not only remarkably improved the permeability of the yeast cell membrane, but also kept yeast cell viability; moreover, the integrity of the yeast cell membrane could be maintained.

A Visualization System for Multiple Heterogeneous Network Security Data and Fusion Analysis

( Sheng Zhang ),( Ronghua Shi ),( Jue Zhao ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.6

Owing to their low scalability, weak support on big data, insufficient data collaborative analysis and inadequate situational awareness, the traditional methods fail to meet the needs of the security data analysis. This paper proposes visualization methods to fuse the multi-source security data and grasp the network situation. Firstly, data sources are classified at their collection positions, with the objects of security data taken from three different layers. Secondly, the Heatmap is adopted to show host status; the Treemap is used to visualize Netflow logs; and the radial Node-link diagram is employed to express IPS logs. Finally, the Labeled Treemap is invented to make a fusion at data-level and the Time-series features are extracted to fuse data at feature-level. The comparative analyses with the prize-winning works prove this method enjoying substantial advantages for network analysts to facilitate data feature fusion, better understand network security situation with a unified, convenient and accurate mode.

Maximum efficiency tracking method based on parameter detection for ICPT systems

Sheng, Xuerui,Shi, Liming The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.9

Efficiency is very important in inductively coupled power transfer (ICPT) systems. To maintain a high efficiency, a maximum efficiency tracking (MET) method based on parameter detection is proposed in the paper. The basic idea is to convert the load value to the active short-circuit (ASC) time interval for the semi-controlled rectifier on the pick-up side. The ASC time interval and the transmitting coil current are detected to calculate the load and mutual inductance values on the transmitting side. According to the detected parameters, the output voltage of the high-frequency inverter that makes the system run at its maximum efficiency can be calculated and controlled. In addition, the load voltage is controlled by the high-frequency rectifier on the pick-up side. Simulation and experimental results show that this method can quickly achieve MET without wireless communication. Furthermore, the difference between the experimental maximum efficiency and the theoretical maximum efficiency is no more than 2%.