Stability analysis of wheeled mobile multirobot coordinated towing system

Xiangtang Zhao,Zhigang Zhao,Shaohui Zhang,Cheng Su 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.1

In the towing process of the wheeled mobile multi-robot coordinated towing system, the overturning of the mobile robot itself will lead to a series of problems such as system damage, operation failure and casualties. In order to adapt to the complex operating environment and complete the towing work safely and effectively, higher requirements are put forward for the carrying capacity, mobile performance and stability of the wheeled mobile multirobot coordinated towing system. Firstly, the spatial configuration of the wheeled multi-robot coordinated towing system is established and the kinematics of the manipulator and towing system are analyzed. The dynamic equations of the manipulator and towing system are established using the Lagrangian method and the Newton-Euler method. Then, the inverse kinematics of the robot is used to solve the joint angles, and the force-angle stability measure is used to analyze the law of overturning stability of the system under three cases of static, static stress and dynamic stress, respectively. Finally, the standard stability angles corresponding to the two sets of joint angles of the robot are compared with the simulation based on the program written in Matlab. The results show that the first set of joint angles has better stability, and some standard stability angles of the system are less than 0 during the motion, the towing system will overturn. Therefore, the first set of joint angles of the manipulator has better stability and should be selected to perform towing tasks. The joint angles of the manipulator should be adjusted to avoid overturning in practice.

A simple preparation method for rare-earth phosphate nano materials using an ionic liquid-driven supported liquid membrane system

Panpan Zhao,Fan Yang,Zhigang Zhao,Qiuxiao Liao,Yang Zhang,Peng Chen,Wanghuan Guo,Ruixi Bai 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-

For the first time, our group has developed a novel, high-flux strategy for shape-controlled synthesis of rare earth nano-materials (CePO4) using ionic liquid(IL)-driven supported liquid membrane (HVHP, DUPAPORE1) system. The system contains three phases including a supply phase of rare earth ions, a feed phase of phosphates, and ionic liquid-driven supporting liquid membrane phase. The imidazolium IL-driven supported liquid membrane is promising for nano-synthetic reaction of CePO4. The anion types of immersed imidazolium IL have a critical role in the formation rate of CePO4 nano-materials. Moreover, the adding SO4 2 anion or adjustment of pH in supply phase containing Ce(III) ions could control effectively the morphology of the CePO4 nano-materials. The result can be regarded as a good example, the IL:[C4mim][Tf2N] driven support liquid membrane systems can be used to prepare nano-wire and nano-sphere structures of CePO4 with high efficiency and flux. Besides, the IL-driven supported liquid membrane can be cycled many times by using the back flush activation method.

Ratio of PM2.5 to PM10 Mass Concentrations in Beijing and Relationships with Pollution from the North China Plain

Zhigang Li,Xin Yang,Chuanfeng Zhao,Tianyi Fan 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.3

Five years of PM2.5/PM10 ratios and their potential relationships with wind and relative humidity (RH) were analyzed for three areas in Beijing (northwestern mountainous area, urban area and southern suburbs), and these values were compared with those of five other cities, including Tianjin, Dalian, Hangzhou, Shanghai and Guangzhou. In the past five years, both PM2.5 and PM10 mass concentrations have decreased over the three Beijing regions, particularly during winters. The PM2.5/PM10 ratios have distinct seasonal characteristics, with more frequent high ratios in winter than in other seasons. The high ratio frequency decrease is most evident in winter and in the southern Beijing suburbs. This fine particle proportion decrease is related to air pollution control policies, including the national project ‘Coal to Gas’. HighPM2.5/PM10 ratios are linked to heavy pollution levels and low wind speeds, indicating the importance of PM2.5 accumulation during pollution events in Beijing. The higher PM2.5/PM10 ratios in Beijing are also closely related to southerly winds and high humidity, indicating the contribution of anthropogenic pollution transported from the south. Due to similar geographic environments, Tianjin is similar to Beijing in terms of the frequency distribution characteristics of the PM2.5/PM10 ratios. The coastal city of Dalian is further north and not similar to Beijing or Tianjin, owing to a sea breeze influence. Different from Beijing and Tianjin, the southern cities of Hangzhou, Shanghai and Guangzhou show almost no change in the PM2.5/PM10 ratio frequency distribution with increases in wind speed and relative humidity.

Cellular Traffic Offloading through Opportunistic Communications Based on Human Mobility

( Zhigang Li ),( Yan Shi ),( Shanzhi Chen ),( Jingwen Zhao ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.3

The rapid increase of smart mobile devices and mobile applications has led to explosive growth of data traffic in cellular network. Offloading data traffic becomes one of the most urgent technical problems. Recent work has proposed to exploit opportunistic communications to offload cellular traffic for mobile data dissemination services, especially for accepting large delayed data. The basic idea is to deliver the data to only part of subscribers (called target-nodes) via the cellular network, and allow target-nodes to disseminate the data through opportunistic communications. Human mobility shows temporal and spatial characteristics and predictability, which can be used as effective guidance efficient opportunistic communication. Therefore, based on the regularity of human mobility we propose NodeRank algorithm which uses the encounter characteristics between nodes to choose target nodes. Different from the existing work which only using encounter frequency, NodeRank algorithm combined the contact time and inter-contact time meanwhile to ensure integrity and availability of message delivery. The simulation results based on real-world mobility traces show the performance advantages of NodeRank in offloading efficiency and network redundant copies.

A New Ambiguity Elimination Method for BSS Block Signals in Time Domain

Wei Zhao,Fengshan Wang,Yuehong Shen,Yuanyuan Wu,Zhigang Yuan,Pengcheng Xu,Pengcheng Xu,Yimin Wei,Wei Jian 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.11

This paper deals with the ambiguity problem of blind source separation (BSS) in the case where continuously received mixture signals are split in time and processed block by block. Due to the inherent permutation and scaling ambiguities of BSS, tying the separated components at each adjacent time blocks doesn’t recover the original source signals correctly in general. Inspired by the Permutation Method of reconstructing source signal blocks in time domain, a new ambiguity elimination approach is proposed in this paper. This method aims to concatenate the separated components in adjacent blocks by artificially setting contrast blocks for each adjacent time blocks. The core idea of this method is to utilize the associativity between components recovered from contrast blocks and corresponding adjacent blocks. Compared with Permutation Method, the main advantage of this new method consists in the fact that it is much more efficient in terms of separation quality and computational speed. Besides, a tradeoff can be adjusted between separation quality and computational speed by choosing different length of contrast blocks. Real-life experiments are performed to validate the performance of this method on the wireless communication system with two transmitting and receiving antennas.

A Novel Wireless Statistical Division Multiplexing Communication System and Performance Analysis

Wei Zhao,Yuehong Shen,Pengcheng Xu,Jiangong Wang,Zhigang Yuan,Yimin Wei,Wei Jian,Hui Li 보안공학연구지원센터 2014 International Journal of Future Generation Communi Vol.7 No.5

Development and verification of PWR core transient coupling calculation software

Li, Zhigang,An, Ping,Zhao, Wenbo,Liu, Wei,He, Tao,Lu, Wei,Li, Qing Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.11

In PWR three-dimensional transient coupling calculation software CORCA-K, the nodal Green's function method and diagonal implicit Runge Kutta method are used to solve the spatiotemporal neutron dynamic diffusion equation, and the single-phase closed channel model and one-dimensional cylindrical heat conduction transient model are used to calculate the coolant temperature and fuel temperature. The LMW, NEACRP and PWR MOX/UO₂ benchmarks and FangJiaShan (FJS) nuclear power plant (NPP) transient control rod move cases are used to verify the CORCA-K. The effects of burnup, fuel effective temperature and ejection rate on the control rod ejection process of PWR are analyzed. The conclusions are as follows: (1) core relative power and fuel Doppler temperature are in good agreement with the results of benchmark and ADPRES, and the deviation between with the reference results is within 3.0% in LMW and NEACRP benchmarks; 2) the variation trend of FJS NPP core transient parameters is consistent with the results of SMART and ADPRES. And the core relative power is in better agreement with the SMART when weighting coefficient is 0.7. Compared with SMART, the maximum deviation is -5.08% in the rod ejection condition and while -5.09% in the control rod complex movement condition.

Effect of Copper on Plasma Ceruloplasmin and Antioxidant Ability in Broiler Chickens Challenged by Lipopolysaccharide

Song, Zhigang,Zhu, Lixian,Zhao, Tong,Jiao, Hongchao,Lin, Hai Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.10

The effects of dietary copper (Cu) supplementation in broiler chickens challenged with a single injection of Salmonella typhymurium lipopolysaccharide (LPS) on the antioxidant capacity and plasma levels of ceruloplasmin (Cp) were evaluated. The broiler chickens were provided with a basal diet or diets supplemented with 8 and 50 mg/kg Cu from 1d of age. At 25d of age, 48 chickens with similar body weight were selected from each diet. Half of the chickens in each dietary treatment were injected intraperitoneally (i.p.) with LPS (1 mg/kg body weight). The other half was injected with saline, serving as the control. Body weight gain and feed consumption were significantly suppressed by LPS challenge during the first 12-h after injection, regardless of dietary Cu levels. Feed efficiency was reduced by LPS injection during the 72-h experimental period. Dietary Cu levels had no significant effect (p>0.05) on the plasma ceruloplasmin concentrations in chickens injected with saline. In contrast, high dietary level of Cu elevated plasma Cp levels in chickens with LPS challenge. Short-term LPS challenge had no significant effect on the antioxidant ability of broilers, as indicated by superoxide dismutase, ferric reducing/antioxidant power and the thiobarbituric acid reacting substances in the plasma. The result suggests that high dietary Cu level (as much as 50 mg/kg supplementation) is favorable for coping with short-term LPS challenge through upregulating plasma Cp levels.

DDAB-MODIFIED TPGS-b-(PCL-ran-PGA) NANOPARTICLES AS ORAL ANTICANCER DRUG CARRIER FOR LUNG CANCER CHEMOTHERAPY

TIEJUN ZHAO,HEZHONG CHEN,LIXIN YANG,HAI JIN,ZHIGANG LI,LIN HAN,FANGLIN LU,ZHIYUN XU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.2

Oral chemotherapy is a great way to cancer treatment because it is less stressful being that the patient will have less hospital visits and can still maintain a close relationship with health care professionals. In this research, three types of nanoparticle formulation from commercial PCL and self-synthesized TPGS-b-(PCL-ran-PGA) diblock copolymer were fabricated for oral delivery of antitumor agents, including DDAB-modified PCL nanoparticles, unmodified TPGS-b-(PCL-ran-PGA) nanoparticles and DDAB-modified TPGS-b-(PCL-ran-PGA) nanoparticles. Firstly, the TPGS-b-(PCL-ran-PGA) diblock copolymer was synthesized and characterized. DDAB was adopted to increase retention time at the cell surface, thus increasing the chances of nanoparticle uptake by the gastrointestinal mucosa and improving drug absorption. The TPGS-b-(PCL-ran-PGA) nanoparticles were found by FESEM of spherical shape and around 200 nm in diameter. The surface charge of TPGS-b-(PCL-ran-PGA) nanoparticles was reversed from anionic to cationic after DDAB modification. The DDAB-modified TPGS-b-(PCL-ran-PGA) nanoparticles have significantly higher level of the cell uptake than that of DDAB-modified PCL nanoparticles and unmodified TPGS-b-(PCL-ran-PGA) nanoparticles. In vitro cell viability studies showed advantages of the DDAB-modified TPGS-b-(PCL-ran-PGA) nanoparticles over Taxotere® in terms of cytotoxicity against A549 cells. In conclusion, oral chemotherapy by DDAB-modified TPGS-b-(PCL-ran-PGA) nanoparticle formulation may provide a promising outcome for lung cancer patients.

A Novel and Efficient Wireless Communication System

Wei Zhao,Yuehong Shen,Zhigang Yuan,Yimin Wei,Wei Jian 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.5

This paper aims to construct a novel wireless communication system, in which source signals are transmitted simultaneously in the same frequency band. The transmitted signals are only required to be statistically independent or statistically distinguished. Therefore, the source signals can be recovered at the receiver by utilizing the classical algorithms of blind source separation (BSS) and independent component analysis (ICA) such as the fast fixed-point algorithm (FastICA). On the one hand, because the source signals are transmitted simultaneously in the same frequency band, the spectrum efficiency of this novel system is much higher than those of time division multiplexing (TDM), frequency division multiplexing (FDM), and code division multiplexing (CDM) systems, in which TDM, FDM and CDM signals are limited in time interval, frequency band and code. On the other hand, inspired by recently proposed reference-based schemes, the reference signals are introduced to the classical separation algorithms of BSS and ICA, which makes this novel system much more efficient than classical ones in terms of computational speed. The performance of this new system is validated through realistic experiments. Additionally, it is theoretically shown that the information content of all the source signal inputs can be recovered by this novel wireless communication system.