Papers by Keyword: Negative Pressure

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Authors: Jing Liang Liu, Zhen Wei, Peng Pan, Hong Tao Zhang
Abstract: The stability of the carbon nanotubes suspension is poor, resulting from the characteristic of insoluble in aqueous solution. Nevertheless, optical limiting devices need long-term stability. In the interest of finding effective and stable materials for optical limiting, we had tried to combine the multi-walled carbon nanotubes (CNTs) and ionic liquids surfactant (hydroxypropyl sulfo imidazoline) to obtain a new dispersion. Ultimately, we achieved non-covalent modification to carbon nanotubes. The electronic structure of the carbon nanotubes’ surface was protected integrality and the dispersion was stable and effective. It was verified by experimental observation through a field scanning electron microscopy (SEM). Finally we did a series of experiments to studied the optical limiting characteristics of the new dispersion. The results manifested that the dispersion system owned well optical limiting properties and better stability, at the same time, we also proved that the negative pressure environment could also do well to optical limiting effect.
Authors: Ying Dao Li, Wei Hong Zhong, Hong Wei Guan, Xiu Shui Ma
Abstract: Negative pressure is the main control variable in scrap copper smelting process, the control of negative pressure is not only closely related with producing safely, but also produces a direct impact on the quality of the anode plate, it is also a key breakthrough in energy saving. This paper first analyses the characteristics of negative pressure control in scrap copper smelting process, aims to larger overshoot and longer regulation under conventional PID control method, and then utilizes fuzzy control to correct the PID parameters online, to achieve the optimization control of negative pressure. Simulation result shows that the adjustment process of optimized control of negative pressure is steady and rapid, usually no or slightly overshoot, and the settling time is also reduced significantly.
Authors: Yu He Li, Kai Sen Guan, Da Peng Zhao, Yong Rong Qiu, Qing Xiang Li
Abstract: In order to meet the mass storage system’s need for higher density and integration, a novel structural design for micro flying head is conceived and an air bearing surface is designed based on micro fluid theory of hydrodynamics. Both positive and negative pressures can be generated by the air bearing surface, with the stiffness and motion stability enhanced by negative pressure. A lubrication model has been investigated with 1.5 order slip model of the generalized Reynolds equation, and the finite volume method is used for the simulation of the flying characteristics. The theoretical analysis and experimental results show that the proposed micro flying head exhibits satisfying flying stability, with head-disk spacing less than 75nm, and carrying capacity exceeding 93mN.
Authors: Xi Chang Zhang, Hai Xia Zhang, Long Di Cheng
Abstract: The flow field in condensing zone of compact spinning with inspiratory groove was developed with Fluent 6.3 and the distribution of velocity was analyzed too. Also the effect of negative pressure on the yarn quality was analyzed and the experiment was done to prove the effect of negative pressure on the yarn qualities. The results show that the fiber can not be compacted well when negative pressure is too small, but it will add the energy consumption, attach the fibers firmly to the bottom of the compact groove by the effect of flow field and reduce the fiber migration, cause the fibers to be absorbed from the holes or the holes to be plugged when the negative pressure is too big. Therefore, in order to ensure the fibers being compacted well and reduce the energy consumption, the selection of negative pressure in compact spinning with inspiratory groove should be less than -3000pa.
Authors: Yi Tong Ma, Fang Xing Li, Xue Shan Gao, Wei Jie Bo
Abstract: The impeller is key element that brings about negative pressure adsorption. The efficiency of the impeller will determine the adsorption capacity of robot. In this paper, physical model is built based on the theory of fluid dynamics by taking a common high speed rotation of impeller as a research object. The basic parameters and boundary conditions are set and a 3D fluid dynamic simulation is done based on FloEFD. The factors such as blade curve, rotational speed and air inlet velocity which have effect on surface flow field impeller are investigated. Then the results are shown by figures and the study analysis is carried on.
Authors: L. Landa, S. Thomsen, R. Hulme
Abstract: A general condition of transformation of a liquid or a crystal into a glass according to results of measurements of specific heats and transition heats is the drop in the internal pressure to negative values.
Authors: Chuan Qi Li, Wei Wang, Jie Gong, Xin Lai Zhao
Abstract: Physical and numerical model studies were performed in order to study the flow conditions for the proposed pump station of Shuangwangcheng reservoir, Shouguang Ctiy. The flow velocity and the pressure distribution in the bidirectional culvert of Shuangwangcheng Pump Station had been obtained by hydraulic model test and numerical simulation. The physical model was constructed to a Froude scale of 1:20. A general conclusion was that, the computed results were good agreement with the data measured in physical model, and could be good complement for physical model test. Furthermore, negative pressure existing in discharge steep culvert in the initial scheme design was eliminated by moving the culvert controlling gate to the end of culvert in the modified scheme, and the flow conditions was improved.
Authors: Di Teng, Fang Xing Li, Xue Shan Gao, Wang Guan
Abstract: This paper introduces a small negative pressure wall-climbing robot with the ARM system. It can complete the task on the surface of vertical, steep. First of all, describes the basic system structure of robot and mechanical configuration. Secondly, the mechanic analyses of robot dynamics modeling to explain the principle of its operation. Finally, an experiment tests the all common functions of the robot.
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