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Chenfei Yan,Zhenguo Sun,Wenzeng Zhang,Qiang Chen 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.7
A multidirectional magnetized permanent magnetic adsorption device (PMAD) for wall-climbing robots is proposed. The novel PMAD can significantly increase the adsorption force under the same mass. Firstly, the magnetic circuit of the novel PMAD was optimized based on the design theory proposed in this paper. The novel PMAD contains multiple closely arranged permanent magnets with different magnetizing directions. The magnets can be divided into several component units by the arrangement regulation of the magnetizing directions. In every component unit, the magnetizing directions distribute along a semi-circle. Secondly, Finite element analysis software Ansys Workbench was used for parameterized modeling, structural characteristic analysis, magnetic circuit simulation, adsorption force calculation and parameter optimization of the novel PMAD. Then, The novel and the Halbach type of PMADs with the same material and volume were trial-produced. The adsorption force was measured under different air gap thicknesses. The experimental results proved that the adsorption force of the novel PMAD doubled averagely compared with the Halbach type of PMAD under the same mass, and the largest amplification was 2.3 times. Finally, the novel PMADs were applied in a wall-climbing robot for ultrasonic testing, and provide steady and reliable adsorption.
Jingtao Zhao,Zhenguo Zhao,Zidong Chen,Zhaojun Lin,Fukai Xu 한국물리학회 2017 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.71 No.12
In this study, we have investigated the electrical properties of the AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with floating gate structures using the measured capacitancevoltage (C-V) and current-voltage (I-V) characteristics. It is found that the two-dimensional electron gas (2DEG) density under the central gate cannot be changed by the floating gate structures. However, the floating gate structures can cause the strain variation in the barrier layer, which lead to the non-uniform distribution of the polarization charges, then induce a polarization Coulomb field and scatter the 2DEG. More floating gate structures and closer distance between the floating gates and the central gate will result in stronger scattering effect of the 2DEG.
Indirectly Self-Adaptive Underactuated Robot Hand with Block-Linkage Mechanisms
Guoxuan Li,Zhenguo Sun,Jian-Jing Jiang,Sylvain Deschamps-Berger,Wenzeng Zhang,Qiang Chen 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
A novel indirectly self-adaptive (ISA) underactuated hand with block-linkage mechanism is developed in this paper. There are twobasic requirements for design of a humanoid robot hand. Firstly, regarding the function of the hand, the hand should be able to stablygrasp common objects with different shapes and sizes. Secondly, regarding the structure of the hand, the hand should be similar toa human hand in its appearance and joint degrees of freedom (DOFs). The ISA Hand reaches the balance point in meeting both ofrequirements. The ISA Hand has 5 fingers, 14 joint DOFs and only 5 motors. There are nine ISA joints in the ISA Hand. All fingersare similar in structure. The thumb has two joints, one in which is the ISA joint. Four fingers in the ISA hand have three joints, twoin which are the ISA joint. The reacting force from objects in grasping process can be used to drive the ISA joint. The architecture,grasping process and force analysis of the ISA finger are given in detail. Experimental results show that the ISA Hand can graspdifferent objects stably.
Visual Saliency Detection Based on color Frequency Features under Bayesian framework
( Naeem Ayoub ),( Zhenguo Gao ),( Danjie Chen ),( Rachida Tobji ),( Nianmin Yao ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.2
Saliency detection in neurobiology is a vehement research during the last few years, several cognitive and interactive systems are designed to simulate saliency model (an attentional mechanism, which focuses on the worthiest part in the image). In this paper, a bottom up saliency detection model is proposed by taking into account the color and luminance frequency features of RGB, CIE L*a*b* color space of the image. We employ low-level features of image and apply band pass filter to estimate and highlight salient region. We compute the likelihood probability by applying Bayesian framework at pixels. Experiments on two publically available datasets (MSRA and SED2) show that our saliency model performs better as compared to the ten state of the art algorithms by achieving higher precision, better recall and F-Measure.
Numerical analysis of Poiseuille-Rayleigh-Bénard convection in supercritical carbon dioxide
Wang Zhipeng,Xu Hong,Chen Chong,Hong Gang,Song Zhenguo,Zhang Yaoli 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.9
The supercritical carbon dioxide (SeCO2) Brayton cycle is an important energy conversion technology for the fourth generation of nuclear energy. Since the printed circuit heat exchanger (PCHE) used in the SeCO2 Brayton cycle has narrow channels, Rayleigh-Benard (RB) convection is likely to exist in the tiny channels. However, there are very few studies on RB convection in supercritical fluids. Current research on RB convection mainly focuses on conventional fluids such as water and air that meet the Boussinesq assumption. It is necessary to study non-Boussinesq fluids. PRB convection refers to RB convection that is affected by horizontal incoming flow. In this paper, the computational fluid dynamics simulation method is used to study the PRB convection phenomenon of non-Boussinesq fluid-supercritical carbon dioxide. The result shows that the inlet Reynolds number (Re) of the horizontal incoming flow significantly affects the PRB convection. When the inlet Re remains unchanged, with the increase of Rayleigh number (Ra), the steady-state convective pattern of the fluid layer is shown in order: horizontal flow, local traveling wave, traveling wave convection. If Ra remains unchanged, as the inlet Re increases, three convection patterns of traveling wave convection, local traveling wave, and horizontal flow will appear in sequence. To characterize the relationship between traveling wave convection and horizontal incoming flow, this paper proposes the relationship between critical Reynolds number and relative Rayleigh number (r).
Development of a Directly Self-adaptive Robot Hand with Pulley-belt Mechanism
Guoxuan Li,Bowen Li,Jie Sun,Wenzeng Zhang,Zhenguo Sun,Qiang Chen 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
Directly self-adaptive under-actuated (DSUA) hands have great potential to stably grasp different objects in unstructured environments. This paper develops a DSUA Hand based on multi-pulley-belt mechanism, which consists of 5 fingers and has 14 DOF. Self-adaptation is designed as the main function of it. The stability of DSUA hand’s grasping process does not highly depend on control algorithm, sensors or control system. This DSUA fingers are based on multi-pulley-belt mechanism. A mathematical model of the 3-joint finger’s contact force is given. Contact force analyses of the DSUA finger are discussed in detail. DSUA Hand weighs 0.94 kg and can grasp objects up to 0.6 kg. The grasping adaptation of DSUA hand is certified by grasping experiments of different objects.
Yanli Liu,Yan Xia,Pan Guo,Guiping Wang,Zhenguo Shen,Yingchun Xu,Yahua Chen 한국원예학회 2013 Horticulture, Environment, and Biotechnology Vol.54 No.4
The effects of environmental factors on the paeonol accumulation in cortex moutan of herbal Paeonia suffruticosa cv. Fengdan were investigated. Cortex moutan of ‘Fengdan’ and the corresponding soil samples were collected from Tongling (Anhui Province, China). A pot experiment was also conducted to investigate the responses of plant growth and paeonol concentrations to copper (Cu) supply. The paeonol and Cu concentrations in cortex moutan samples, the basic soil properties and soil’s bacterial diversity were analyzed. The results showed that moderate levels of Cu in the soil enhanced the paeonol concentration in the cortex moutan. Moreover, the paeonol concentration was related significantly to soil bacterial diversity. The results of the pot experiment showed that increasing Cu supply from 63 to 263 mg·kg-1 did not produce any significant effect on the dry weight of ‘Fengdan’ cortex moutan,duramen, and total plant. Increasing Cu supply significantly increased the concentrations of paeonol in cortex moutan and duramen; but at 263 mg·kg-1 Cu there was a slight decline in their concentrations than those obtained at 156mg·kg-1 Cu. In all treatments, the concentrations of paeonol were much higher in the cortex moutan than those in the duramen. Due to its ecological benefits, ‘Fengdan’ can be planted in soil contaminated with moderate Cu.
Jingjuan Hu,Haihua Luo,Jieyan Wang,Wenli Tang,Junqi Lu,Shan Wu,Zhi Xiong,Guizhi Yang,Zhenguo Chen,Tian Lan,Hongwei Zhou,Jing Nie,Yong Jiang,Peng Chen 생화학분자생물학회 2017 Experimental and molecular medicine Vol.49 No.-
Chronic high-salt diet-associated renal injury is a key risk factor for the development of hypertension. However, the mechanism by which salt triggers kidney damage is poorly understood. Our study investigated how high salt (HS) intake triggers early renal injury by considering the ‘gut-kidney axis’. We fed mice 2% NaCl in drinking water continuously for 8 weeks to induce early renal injury. We found that the ‘quantitative’ and ‘qualitative’ levels of the intestinal microflora were significantly altered after chronic HS feeding, which indicated the occurrence of enteric dysbiosis. In addition, intestinal immunological gene expression was impaired in mice with HS intake. Gut permeability elevation and enteric bacterial translocation into the kidney were detected after chronic HS feeding. Gut bacteria depletion by non-absorbable antibiotic administration restored HS loadinginduced gut leakiness, renal injury and systolic blood pressure elevation. The fecal microbiota from mice fed chronic HS could independently cause gut leakiness and renal injury. Our current work provides a novel insight into the mechanism of HS-induced renal injury by investigating the role of the intestine with enteric bacteria and gut permeability and clearly illustrates that chronic HS loading elicited renal injury and dysfunction that was dependent on the intestine.