Adaptive Second-order Sliding Mode Control of Electrical Throttles Based on Online Zero-crossing Checking

Yun Long,Chong Yao,En-Zhe Song,Quan Dong,Yan-Min Wang 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.2

In this paper, an adaptive second-order sliding mode control approach is proposed for the performance improvement of electronic throttles (ET). Based on the traditional twisting approach, a novel adaptation mechanism based on the online zero-crossing checking is contained in the modified approach to make the control magnitude of the controller at the minimum admissible level. The idea behind it is to calculate the number of zero-crossings of the sliding surface in real time. The guaranteed stability condition and convergence region of the system are also deduced. In order to further prove its high adaptation capability, the commonly used adaptation mechanism called the Lyapunov-based type is also introduced for comparative study. Simulations and experiments validate the proposed approach with the advantages of chattering elimination, high speed and accuracy in the control of ET systems.

A cavitation performance prediction method for pumps PART1-Proposal and feasibility

Yun, Long,Rongsheng, Zhu,Dezhong, Wang Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.11

Pumps are essential machinery in the various industries. With the development of high-speed and large-scale pumps, especially high energy density, high requirements have been imposed on the vibration and noise performance of pumps, and cavitation is an important source of vibration and noise excitation in pumps, so it is necessary to improve pumps cavitation performance. The modern pump optimization design method mainly adopts parameterization and artificial intelligence coupling optimization, which requires direct correlation between geometric parameters and pump performance. The existing cavitation performance calculation method is difficult to be integrated into multi-objective automatic coupling optimization. Therefore, a fast prediction method for pump cavitation performance is urgently needed. This paper proposes a novel cavitation prediction method based on impeller pressure isosurface at single-phase media. When the cavitation occurs, the area of pressure isosurface S_iso increases linearly with the NPSH_a decrease. This demonstrates that with the development of cavitation, the variation law of the head with the NPSH_a and the variation law of the head with the area of pressure isosurface are consistent. Therefore, the area of pressure isosurface S_iso can be used to predict cavitation performance. For a certain impeller blade, since the area ratio R_s is proportional to the area of pressure isosurface S_iso, the cavitation performance can be predicted by the R_s. In this paper, a new cavitation performance prediction method is proposed, and the feasibility of this method is demonstrated in combination with experiments, which will greatly accelerate the pump hydraulic optimization design.

The Effect of Different Inflows on the Unsteady Hydrodynamic Characteristics of a Mixed Flow Pump

Yun, Long,Dezhong, Wang,Junlian, Yin,Youlin, Cai,Chao, Feng Korean Society for Fluid machinery 2017 International journal of fluid machinery and syste Vol.10 No.2

The problem of non-uniform inflow exists in many practical engineering applications, such as the elbow suction pipe of waterjet pump and, the channel head of steam generator which is directly connect with reactor coolant pump. Generally, pumps are identical designs and are selected based on performance under uniform inflow with the straight pipe, but actually non-uniform suction flow is induced by upstream equipment. In this paper, CFD approach was employed to analyze unsteady hydrodynamic characteristics of reactor coolant pumps with different inflows. The Reynolds-averaged Naiver-Stokes equations with the $k-{\varepsilon}$ turbulence model were solved by the computational fluid dynamics software CFX to conduct the steady and unsteady numerical simulation. The numerical results of the straight pipe and channel head were validated with experimental data for the heads at different flow coefficients. In the nominal flow rate, the head of the pump with the channel head decreases by 1.19% when compared to the straight pipe. The complicated structure of channel head induces the inlet flow non-uniform. The non-uniformity of the inflow induces the difference of vorticity distribution at the outlet of the pump. The variation law of blade to blade velocity at different flow rate and the difference of blade to blade velocity with different inflow are researched. The effects of non-uniform inflow on radial forces are absolutely different from the uniform inflow. For the radial forces at the frequency $f_R$, the corresponding amplitude of channel head are higher than the straight pipe at $1.0{\Phi}_d$ and $1.2{\Phi}_d$ flow rates, and the corresponding amplitude of channel head are lower than the straight pipe at $0.8{\Phi}_d$ flow rates.

Shear behavior and shear capacity prediction of precast concrete-encased steel beams

Yunlong Yu,Yong Yang,Yicong Xue,Yaping Liu 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.36 No.3

A novel precast concrete-encased steel composite beam, which can be abbreviated as PCES beam, is introduced in this paper. In order to investigate the shear behavior of this PCES beam, a test of eight full-scale PCES beam specimens was carried out, in which the specimens were subjected to positive bending moment or negative bending moment, respectively. The factors which affected the shear behavior, such as the shear span-to-depth aspect ratio and the existence of concrete flange, were taken into account. During the test, the load-deflection curves of the test specimens were recorded, while the crack propagation patterns together with the failure patterns were observed as well. From the test results, it could be concluded that the tested PCES beams could all exhibit ductile shear behavior, and the innovative shear connectors between the precast concrete and cast-in-place concrete, namely the precast concrete transverse diaphragms, were verified to be effective. Then, based on the shear deformation compatibility, a theoretical model for predicting the shear capacity of the proposed PCES beams was put forward and verified to be valid with the good agreement of the shear capacities calculated using the proposed method and those from the experiments. Finally, in order to facilitate the preliminary design in practical applications, a simplified calculation method for predicting the shear capacity of the proposed PCES beams was also put forward and validated using available test results.

Effects of the Inlet Position of Blade on the Performance of a Centrifugal Impeller

Yunlong Li,Ruizi Zhang,Kaibin Wang,Jingyin Li 한국유체기계학회 2018 International journal of fluid machinery and syste Vol.11 No.3

The effects of the inlet position of blade on the performance of a centrifugal impeller are numerically investigated. The inlet position of the blade can be determined by the outer diameter, the leaning angle of the blade inlet, the shroud and hub angular momentums specified at the blade inlet. It is found that the flow fields of the optimal impeller are obviously superior to those of the impeller whose blade leading edge was installed at impeller eye. The range analyses reveal that angular momentum specified at the inlet hub is the least important factor in affecting the efficiency of impeller, while the outer diameter of blade leading edge plays the most important role in determining the pressure ratio.

Angle-sensitive Pixels Based on Subwavelength Compound Gratings

Yunlong Meng,Xuemei Hu,Cheng Yang,Xinyu Shen,Xueyun Cao,Lankun Lin,Feng Yan,Tao Yue 한국광학회 2022 Current Optics and Photonics Vol.6 No.4

In this paper, we present a new design for angle-sensitive pixels (ASPs). The proposed ASPs take advantage of subwavelength compound gratings to capture the light angle, which enables pixel size to reach the wavelength scale of 0.7 μm × 0.7 μm. The subwavelength compound gratings are implement-ed by the wires of the readout circuit inherent to the standard complementary metal–oxide–semiconductor manufacturing process, thus avoiding additional off-chip optics or post-processing. This technique allows the use of two pixels for horizontal or vertical angle detection, and can determine the light’s angle in the range from −45° to +45°. The proposed sensor enables surface-profile reconstruction of mi-croscale samples using a lensless imaging system.

Morphological characteristics and gene mapping of a dense panicle (dp2) mutant in rice (Oryza sativa L.)

Yunlong Yang,Chunhai Shi,Yuanfei Zhou,Jianguo Wu,Xiaoli Jin,Jianyao Shou 한국유전학회 2014 Genes & Genomics Vol.36 No.3

A dense panicle mutant (dp2) derived from theOryza sativa ssp. japonica cultivar Nipponbare through ethylmethane sulfonate mutagenesis was used in present study. Compared to the wild type, the panicle of dp2 mutantexhibited more branches and denser grains. Further more, thenumber of spikelets per panicle, number of primary branchesand secondary branches of dp2 mutant were significantlyincreased while the panicle length, and 1,000-grain weightwere significantly decreased. The results from the geneticanalysis indicated that the dense panicle phenotype wascontrolled by a single dominance nuclear gene. Polymorphicanalysis of SSR and InDel markers demonstrated that theDP2 gene was located at the long arm of chromosome 2,which was further mapped between SSR markers RM341and RM13356 in a physical region of 398 kb. Within thisregion, the RCN2 (LOC_Os02g32950) gene which wasannotated relating to the development of rice panicle wasfound. Compared to the wild type, the sequence of RCN2gene in the dp2 mutant showed that two SNPs replacementhad taken place in the promoter region (G–A) and the intronregion (A–T), respectively. The dp2 mutant could be a novelmutant of RCN2 gene and this novel mutant might be usefulfor further studies on this gene.

Ballast Mechanical Performance with and without Under Sleeper Pads

Yunlong Guo,Jianxi Wang,Valeri Markine,Guoqing Jing 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.11

With the train speed and axle load increasing, excessive stresses are produced and transmitted to the ballast layer, inducing rapid ballast degradation. To solve this issue, the under sleeper pads (USPs) have been widely applied between sleepers and ballast particles as the elastic layer. In this research, laboratory tests using half-sleeper track were carried out to study the ballast bed performance with or without the USPs under static and cyclic loading. Results show that applying the USPs reduces the track stiffness and can decrease the settlement. However, installing the USPs increases the ballast bed acceleration and the sleeper vertical acceleration. The contact areas of sleeper-ballast with USPs are over 5 times as those without USPs. The USPs assist reducing ballast degradation mainly by avoiding the ballast particle breakage at the sleeper-ballast interface and can increase the stress distribution at the longitudinal direction.

Microstructure and Hydrogen Absorption Properties of a BCC Phase Accompanied Laves Alloy

Yunlong Zhang,Tiebang Zhang,Jinshan Li,Ruolin Li,Yun Yu,Yalin Lu 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.3

A non-stoichiometry Zr0.7Ti0.4V1.5Cr0.4alloy has been synthesized by arc melting following annealing treatment or meltspinningto obtain the bulk and ribbon samples, respectively. XRD investigation reveals the multiphase structure consistingof C15-Laves, V-BCC and a small amount of α-Zr or Zr3V3O. The alloy shows easy activation and fast hydrogenationkinetics. The annealed alloy absorbs 2.51 wt% H at room temperature, higher than the melt-spun ribbons. Refined grains bymelt-spinning accelerates the hydrogenation of bulk alloy. The absorption behavior in presence of 1 mol% air has been testedto evaluate the anti-poisoning ability. Pressure–composition–temperature characteristics and thermodynamics parametersindicate the low equilibrium pressure and high hydrides stability. Hydrides investigation reveals that the Laves phase dominantmultiphase structure contributes to the enhanced hydrogen capacity and multi-stage hydrogen release in DSC curve.

MODEL PREDICTIVE COORDINATED CONTROL FOR DUAL-MODE POWER-SPLIT HYBRID ELECTRIC VEHICLE

Yunlong Qi,Changle Xiang,Weida Wang,Boxuan Wen,Feng Ding 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.2

Power-split hybrid electric vehicles (HEVs) have great potential fuel efficiency and have attracted extensive research attention with regard to their control system. The coordinated controller in HEV plays an important role in tracking the optimal state reference generated by the energy management strategy (EMS), so as to reach the desired fuel efficiency. Meanwhile, the coordinated controller also has a significant impact on driving performance. To improve its performance, the design of a model predictive control (MPC) based coordinated controller in power-split HEV is presented. First, a non-linear, time-varying constrained control oriented transmission model of a dual-mode power-split HEV is formulated to describe this control problem. Then, to solve this problem, the non-linear part in the transmission model is linearised, and a linear MPC is used to obtain the control signals for the motors and engine at each time step. To meet the requirements of real-time computation, a fast MPC method is also applied to reduce the online computation effort. Simulations and experiments demonstrate the effectiveness of the proposed MPC-based coordinated controller.