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Double-layer Dynamic Decoupling Control System for the Yaw Stability of Four Wheel Steering Vehicle
Ke Shi,Xiaofang Yuan,Qian He 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.5
The four-wheel steering (4WS) is an efficient method to improve the manoeuvrability of electric vehiclewith the tendency of understeer, by providing the sufficient steering angles. Because of the various kinds of drivingenvironments, the inner coupling between the active front and rear wheels of the 4WS vehicle is a challengingproblem, which usually results in unstable yaw stability of the vehicle. In order to solve this coupling problem,this paper presents a double-layer dynamic decoupling control system (DDDCS), which consists of an upper partdynamicdecoupling unit (DDU) and a lower part-steering control unit (SCU). The DDU is presented to solve thedynamic coupling problem between the active front and rear wheels, and separately establishes two decoupledmodels by the diagonal decoupling method. The SCU is designed to obtain the decoupled control signals by themodel predictive controller, then, the yaw stability of 4WS vehicle can be guaranteed. The results of the simulationshow that the proposed DDDCS has good decoupling performance and stable yaw performance for 4WS vehicle.
Shi-Ke Liang,Zi-Qiang Liang,Xiao-Sui Zhou,Jia-Lin Chen,Guang-Hong Li,Fang-Hai Wang 한국응용곤충학회 2015 Journal of Asia-Pacific Entomology Vol.18 No.3
Sogatella furcifera is amajor rice pest that exhibits wing dimorphism. The methylation-sensitive representational difference analysis (MS-RDA) is widely used in plants and some animals to identify methylation differences in genomic DNA regions. However the method has been applied to insects very less. The objective of the current research was tomonitor differential cytosine methylations at CCGG sequences inmacropterous and brachypterous adults of female S. furcifera to determine the association between gene methylation and wing phenotypes using MS-RDA. After the second subtractive hybridization, two differentially methylated DNA fragments were obtained. These DNA fragments were then cloned into the pGEM-T vector and sequenced. One fragment fromthe positive hybridization was 464 bp, and highly similar to the 18S ribosomal RNA (rRNA) genes from some animals. Another fragment from the reverse hybridization was 453 bp, and homologous to the 28S rRNA gene of S. furcifera with a similarity rate as high as 99%. These results provide potential evidence that DNA methylation of rRNA genes may be related to wing phenotype variations in S. furcifera, and will facilitate future studies on the epigenetic mechanisms of insect wing polymorphism.
Room-temperature tensile strength and thermal shock behavior of spark plasma sintered W-K-TiC alloys
Ke Shi,Bo Huang,Bo He,Ye Xiao,Xiaoliang Yang,Youyun Lian,Xiang Liu,Jun Tang 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.1
W-K-TiC alloys with different titanium carbide concentrations (0.05, 0.1, 0.25, 0.5, 1, 2) wt.% werefabricated through Mechanical Alloying and Spark Plasma Sintering. The effects of the addition of nanoscaledTiC particles on the relative density, Vickers micro-hardness, microstructure, crystal information,thermal shock resistance, and tensile strength were investigated. It is revealed that the doped TiC nanoparticleslocated at the grain boundaries. The relative density and Vickers micro-hardness of W-K-TiCalloys was enhanced with TiC addition and the highest Vickers micro-hardness is 731.55. As the TiCaddition increased from 0.05 to 2 wt%, the room-temperature tensile strength raised from 141 to353 MPa. The grain size of the W-K-TiC alloys decreased sharply from 2.56 mm to 330 nm with theenhanced TiC doping. The resistance to thermal shock damage of W-K-TiC alloys was improved slightlywith the increased TiC addition
Morphology and Phylogeny of Neoscytalidium orchidacearum sp. nov. (Botryosphaeriaceae)
( Shi-ke Huang ),( Narumon Tangthirasunun ),( Alan J. L. Phillips ),( Dong-qin Dai ),( Dhanushka N. Wanasinghe ),( Ting-chi Wen ),( Ali H. Bahkali ),( Kevin D. Hyde ),( Ji-chuan Kang ) 한국균학회 2016 Mycobiology Vol.44 No.2
A coelomycete with characters resembling the asexual morphs in the family Botryosphaeriaceae was isolated from a fallen leaf of an orchid collected in Thailand. Morphological and phylogenetic analyses placed the strain in Neoscytalidium. Phylogenetic relationships among Neoscytalidium species were inferred by analyzing internal transcribed spacers and large subunit of rRNA sequence data and indicate that our strain is a new species, which is introduced and illustrated herein as Neoscytalidium orchidacearum sp. nov.
Shi-Tang Ke,Wenlin Yu,Yao-Jun Ge 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.70 No.4
In the current code design, the use of a uniform internal pressure coefficient of cooling towers as internal suction cannot reflect the 3D characteristics of flow field inside the tower body with different ventilation rate of shutters. Moreover, extreme weather such as heavy rain also has a direct impact on aerodynamic force on the internal surface and changes the turbulence effect of pulsating wind. In this study, the world\'s tallest cooling tower under construction, which stands 210m, is taken as the research object. The algorithm for two-way coupling between wind and rain is adopted. Simulation of wind field and raindrops is performed iteratively using continuous phase and discrete phase models, respectively, under the general principles of computational fluid dynamics (CFD). Firstly, the rule of influence of 9 combinations of wind speed and rainfall intensity on the volume of wind-driven rain, additional action force of raindrops and equivalent internal pressure coefficient of the tower body is analyzed. The combination of wind velocity and rainfall intensity that is most unfavorable to the cooling tower in terms of distribution of internal pressure coefficient is identified. On this basis, the wind/rain loads, distribution of aerodynamic force and working mechanism of internal pressures of the cooling tower under the most unfavorable working condition are compared between the four ventilation rates of shutters (0%, 15%, 30% and 100%). The results show that the amount of raindrops captured by the internal surface of the tower decreases as the wind velocity increases, and increases along with the rainfall intensity and ventilation rate of the shutters. The maximum value of rain-induced pressure coefficient is 0.013. The research findings lay the basis for determining the precise values of internal surface loads of cooling tower under extreme weather conditions.
Corrosion of Fe<sub>3</sub>Al-4Cr Alloys at 1000°C in N<sub>2</sub>-0.1%H<sub>2</sub>S Gas
Shi, Yu Ke,Lee, Dong Bok Trans Tech Publications, Ltd. 2018 Key Engineering Materials Vol.765 No.-
<P>Pure Fe3Al and Fe3Al+4%Cr alloys were corroded at 1000 °C for up to 200 h in N2-0.1%H2S-mixed gas in order to study their corrosion behavior in H2S-containing atmosphere. The formed scales consisted primarily of α-Al2O3, FeAl2O4, and Fe2O3. In these oxide scales, hydrogen and sulfur dissolved according to the reaction; H2S→2H+S. Corrosion products of Cr were not identified in the scales from the XRD analysis, indicating that Cr dissolved in the oxide scales. Fe3Al+4%Cr alloy displayed poorer corrosion resistance than Fe3Al alloy, indicating that chromium accelerated the corrosion rates of Fe3Al alloys.</P>
Shi-Tang Ke,Yifan Dong,Rongkuan Zhu,Tongguang Wang 한국풍공학회 2020 Wind and Structures, An International Journal (WAS Vol.30 No.4
The strong turbulence characteristic of typhoon not only will significantly change flow field characteristics surrounding the large-scale wind turbine and aerodynamic force distribution on surface, but also may cause morphological evolution of coast dune and thereby form sand storms. A 5MW horizontal-axis wind turbine in a wind power plant of southeastern coastal areas in China was chosen to investigate the distribution law of additional loads caused by wind-sand coupling movement of coast dune at landing of strong typhoons. Firstly, a mesoscale Weather Research and Forecasting (WRF) mode was introduced in for high spatial resolution simulation of typhoon “Megi”. Wind speed profile on the boundary layer of typhoon was gained through fitting based on nonlinear least squares and then it was integrated into the user-defined function (UDF) as an entry condition of small-scaled CFD numerical simulation. On this basis, a synchronous iterative modeling of wind field and sand particle combination was carried out by using a continuous phase and discrete phase. Influencing laws of typhoon and normal wind on moving characteristics of sand particles, equivalent pressure distribution mode of structural surface and characteristics of lift resistance coefficient were compared. Results demonstrated that: Compared with normal wind, mesoscale typhoon intensifies the 3D aerodynamic distribution mode on structural surface of wind turbine significantly. Different from wind loads, sand loads mainly impact on 30° ranges at two sides of the lower windward region on the tower. The ratio between sand loads and wind load reaches 3.937% and the maximum sand pressure coefficient is 0.09. The coupling impact effect of strong typhoon and large sand particles is more significant, in which the resistance coefficient of tower is increased by 9.80% to the maximum extent. The maximum resistance coefficient in typhoon field is 13.79% higher than that in the normal wind field.