Performance analysis of 3-PPRU parallel mechanism with a completely/partially/ non constant Jacobian matrix

Yachao Cao,Tie Zhang,Yanzhi Zhao,Guangcai Ma 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.10

This paper proposes a 3-PPRU parallel mechanism (PM) with a completely/ partially/non constant Jacobian matrix. Based on screw theory and selecting actuating components theory, the reasonability of the actuating input selection is analyzed. By different actuating selection, the Jacobian matrix of the PM can realize completely/partially/non constant. The direct, inverse and combined kinematic singularities of the PM with three different Jacobian matrices are discussed. The velocity, payload and stiffness performance of the PM are discussed and compared. A new index, as auxiliary evaluation index, is proposed first.

Effect of an electric field on the molecular properties of tributyrin, tricaproin and tricaprylin: a theoretical study

Wang Yachao,Lin Xiaoran,Wang Mei 한국물리학회 2021 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.79 No.4

Tributyrin, tricaproin and tricaprylin molecules are typical representatives of short-medium chain-saturated triglycerides and maybe used as additives to improve the viscosity of natural ester insulating oil. In this work, we study the effect of an electric field on the molecular properties of the three molecules using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The level of electric field intensity during streamer initiation and propagation in insulating oil was considered for the intensities from – 3.8 × 109 V/m to 3.8 × 109 V/m. The molecular structures, infrared spectra, orbital energies and excited states under different applied electric fields were calculated. The molecular structures of the three kinds of molecules showed obvious changes and the Stark effect was observed under the electric field. Compared with tributyrin and tricaproin, the electric field has more influence on the orbital energy level of tricaprylin. The ionization potential of tricaprylin was reduced by about 25% when the electric field intensity was 3.8 × 109 V/m. The calculated results for the excited states show that the dependence of the excitation energy on the intensity of electric field was not as strong as that of the ionization potential on the electric field. On the whole, tributyrin and tricaproin showed more stable properties than tricaprylin under an applied electric field. The results can deepen our understanding of the discharge mechanism of natural esters under an applied electric field, especially the characteristics of the short-chain-saturated triglycerides. They also provide theoretical support for the improved performance of natural ester insulating oil.

VPIT : An Improved Range-Free Localization Algorithm Using Voronoi Diagrams for Wireless Sensor Networks

Xingming Sun,Yachao Hu,Baowei Wang,Jian Zhang,Tao Li 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.8

Localization systems have been identified as key issues in the development and operation of wireless sensor networks. The global positioning system (GPS) solves the problem about localization, but it is not suitable for wireless sensor networks. Due to range-free localization approaches requiring low equipped hardware and easy to implement, it is widely used in WSNs localization system. When the node communication radius increases, the accuracy of area-based localization is reduced. It is important to improve the localization accuracy in this situation. In this paper, to improve the accuracy of the node localization, we propose a new range-free localization using Voronoi diagrams based approximate point-in-triangulation test (APIT) algorithm. We compare our algorithm with APIT. Simulation results show that the VPIT improved the precision of localization by narrowing the node's geometry region.

Experimental Study of Seismic Damage with Park-Ang Model for Recycled Aggregate Concrete Columns

Yujiang Fan,Ziqiang Guo,Yachao Wang,Pengcheng Zhao,Binshan Yu 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.9

By means of the low cycle loading tests on six recycled aggregate concrete (RAC) columns with different proportions, in combination with the Park-Ang two-parameter damage model suitable for ordinary concrete columns and the damage degree Dc of actual structures, the calculated value of cyclic loading coefficient β of recycled aggregate concrete columns was determined. It would be achieved by analyzing the calculated β that the impact of the replacement ratio of recycled aggregate and the content of mixed fibers on β was significantly different. Considering the reinforcement ratio mentioned in paper. Matlab was further employed to fit multivariable linear equation regarding recycled aggregate replacement ratio, mixed fibers contents and reinforcement rate as the basis, so that the computation formula of the cyclic loading coefficient β suitable for recycled aggregate concrete columns was revealed.

Trajectory tracking control of a 3-CRU translational parallel robot based on PD+robust controller

Tie Zhang,Guangcai Ma,Yachao Cao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8

In order to suppress the external disturbances existing in the trajectory tracking process of the 3-CRU parallel robot, a trajectory tracking control method based on PD+robust controller is proposed in this paper. The kinematic model of the 3-CRU parallel robot is established to solve the kinetic energy and potential energy of the system. The basic dynamic model of the 3-CRU parallel robot is obtained based on Lagrangian formulation, and the complete dynamic model of the parallel robot is established by introducing Coulomb and viscous friction. Based on the analysis of the factors affecting the stability of PD controller, a trajectory tracking control method based on PD+robust controller is proposed, and it is proved theoretically that the system converges stably and has a good external disturbance suppression effect. The method has the characteristics of easy implementation and strong applicability of PD controller and strong robustness of robust controller. Experimental results prove the effectiveness of this method.

Evaluation of sex attractants for monitoring of Illiberis ulmivora Graeser (Lepidoptera: Zygaenidae: Procridinae): Height, distance, placement, climatic conditions

Liu Hongxia,Dou Rui,Wang Jifei,Zhu Yachao,Li Jingyao,Liu Jinlong,Wang Yang,Zhang Jintong,Jing Xiaoyuan 한국곤충학회 2022 Entomological Research Vol.52 No.2

The phytophagous caterpillar Illiberis ulmivora is a serious pest of Ulmus glaucescens Franch (Ulmaceae, Ulmus). In order to test potent sex attractant, field trails of synthetic candidate attractants were conducted in China. In this study, baits with ternary blends, (2S)-butyl (7Z)-dodecenoate, (2S)-butyl (9Z)-tetradecenoate, and (2S)-butyl (5Z)-decenoate (8:4:1 ratio) resulted in a higher number of male moths capture than the rest of the baits that were offered. Traps positioned at a height of 1.2 m attracted more males than those installed at heights of 2.2 m and 3.2 m. The slope aspect, temperature and humility had a significant effect on the trap catches. More catches occurred in traps placed on semi-shady and semi-sunny slopes than those placed on sunny and shady slopes. The number of pheromones in the septa decreased with age. The residual amounts of pheromones in the lures combined with 2,6-di-tert - butyl-p-cresol (BHT) were higher than those in the control. However, there were no differences in the male captures between components and components combined with BHT during the first 8 d. These findings on monitoring and trap positions can be used to predict the occurrence and population dynamics of I. ulmivora, to develop ecological management of I. ulmivora.

A Modified Extraction Method of Circulating Free DNA for Epidermal Growth Factor Receptor Mutation Analysis

Haihua Yuan,Bin Jiang,Zhong-Zheng Zhu,Yachao Lu,Feng Liu,Wenying Zhang,Gang Huang,Guanshan Zhu 연세대학교의과대학 2012 Yonsei medical journal Vol.53 No.1

Purpose: Circulating free DNA (cfDNA) in plasma is promising to be a surrogate for tumor tissue DNA. However, not all epidermal growth factor receptor (EGFR) mutations in tumor tissue DNA has been detected in matched cfDNA, at least partly due to inefficient cfDNA extraction method. The purpose of this study was to establish an efficient plasma cfDNA extraction protocol. Materials and Methods: The yield of plasma cfDNA extracted by our modified phenol-chloroform (MPC) method from non-small-cell lung cancer (NSCLC) patients was compared with that by QIAamp MinElute Virus Spin kit (Qiagen kit) as control, using the Wilcoxon rank-sum test. TaqMan quantitative polymerase chain reaction (qPCR) assays were used to quantify the plasma cfDNA extracted. Both Mutant-enriched PCR (ME-PCR) coupled sequencing and DxS EGFR mutation test kit were used to evaluate the impact of extraction method on EGFR mutation analysis. Results: MPC method extracted more plasma cfDNA than Qiagen kit method (p=0.011). The proportion of longer fragment (≥202 bp) in cfDNA extracted by MPC method was significantly higher than by Qiagen kit method (p=0.002). In the sequencing maps of ME-PCR products, a higher mutant peak was observed on plasma cfDNA extracted by MPC method than by Qiagen kit method. In DxS EGFR mutation test kit results, plasma cfDNA extracted by MPC method contained more tumor-origin DNA than by Qiagen kit method. Conclusion: An improved plasma cfDNA extraction method of MPC is provided, which will be beneficial for EGFR mutation analysis for patients with NSCLC.

Investigation of Aluminate Coupling Agent as Modifier and Its Application on Improving Flame Retardant of Intumescent Flame Retardant Coatings

Haoran Jiang,Yong Jiang,Xianli Zhu,Yachao Wang 한국고분자학회 2020 Macromolecular Research Vol.28 No.13

Intumescent flame retardant coating modified by aluminate coupling agent were prepared via sol-gel method using ammonium polyphosphate, polyacrylamide, aluminate coupling agent (ACA), and boron nitride (BN). The effect of modification of ACA on its flame retardant and characterization were preliminarily studied by cone calorimeter, scanning electron microscope, surface tensiometer and contact angle measurement. It is found that the addition of ACA can increase the expansion rate of carbon layer, and a stronger blocking effect can lead to a better property of flame retardant. The sample containing BN, after being modified by 3M NaOH and ACA, dramatically decreases heat release rate, especially reduce the peak heat release rate (pHRR) by 54% and total heat release by 16%, respectively. Moreover, the time to ignition was delayed by 175%. Through examining the residues and pyrolysis products of the coating samples, the mechanism of enhanced flame retardant that promotes the char-forming and heat barrier of the modification of ACA and BN is proposed. This work can offer a significant guide for further studying of ACA and modified BN on the flame retardant.

An Improved Interacting Multiple Model Algorithm for Target Tracking Based on ANFIS

Zengqiang Ma,Yacong Zheng,Sha Zhong,Xingxing Zou,Yachao Li 보안공학연구지원센터 2014 International Journal of Signal Processing, Image Vol.7 No.5

IMM (Interacting Multiple Model) algorithm is widely used in target tracking, and its basic principle is described in detail at first. However, the IMM algorithm fails to obtain the prior probability of model conversion quickly and accurately when tracking for target. In this paper, an improved IMM algorithm based on ANFIS (the adaptive neural fuzzy inference system) is proposed. The improved algorithm can update the value of system noise covariance in real-time by ANFIS module through observing the coefficient of system noise covariance. Consequently, the probability of model conversion can be obtained more quickly and accurately. Then, the comparison and analysis of the experiment results between the original IMM algorithm and the improved one have been carried out. The experiment results show that the reaction rate for maneuvering target tracking is significantly boosted and tracking error is obviously reduced because the improved algorithm can update the value of system noise covariance in real-time and improve the system adaptability.