Papers by Keyword: Contact Time

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Authors: Hui Zhi Zheng, Xiao Feng Hu, Zhao Heng Du, Wei Liu
Abstract: The electrostatic charge accumulates on the surface of the aerial vehicle when flying. And the electrostatic discharge would impact the aerial vehicle and the airborne equipment enormously. In order to study the triboelectrifiction of the aerial vehicle skin material and space particle, the triboelectrifiction principle of the skin material is analyzed, and aerial vehicle skin material triboelectrifiction experimental platform has been designed. Lots of troubles are overcome like the relatively high speed of aerial vehicle and space particles, required high bleeder resistance for analog devices, and testing problem of friction potential. The rotary friction method, composite insulating layer, contact electrostatic potential test method are adopted for the experimental platform. And aerial vehicle skin material has been tested using the test platform. From the experimental results, the friction contact time, the separation process, and the contact area are analyzed. So the material electrostatic test platform can be used as material electrostatic charge experimental research equipment.
Authors: Qin Wei Ma, Li Ning Yun, Shao Peng Ma, Hong Tao Wang
Abstract: An experimental study on collision dynamics characteristics of big concrete block is presented. In order to obtain the recovery coefficient and contact time, a special measuring system is constructed. The experimental results show that the recovery coefficient is increased with the rise of collision velocity but the variation of contact time with collision velocity is opposite. Meanwhile the recovery coefficient of high level concrete is also larger than that of the low level. The inner damage of material in the collision recorded by AE sensors is measured and the results indicated it was the main reason that leads to the energy loss.
Authors: Jin Feng Lu, Yong Zhang, Yan Fang Liu, Shang Chao Yue, Jun Ma
Abstract: This work comparatively investigated the formation of ketoacids of a filtered river water in synthetic goethite-catalyzed ozonation and ozonation alone. Results indicate that the catalytic ozonation produces less pyruvic acids and total ketoacids than ozonation alone. In addition, the yields of total ketoacids of the filtered water after catalytic ozonation increased as ozone dose increased and contact time extended. In comparison to ozonation alone, FeOOH/O3 further enhanced the degree of oxidation of the macromolecular intermediates or by-products such as pyruvic acid due to more •OH generation. However, Bio-filtration is still proposed to follow the catalytic ozonation to ensure the microbial stability in water distribution systems.
Authors: Sheila Devasahayam, Prasad Yarlagadda
Abstract: Superhydrophobicity is directly related to the wettability of the surfaces. Cassie-Baxter state relating to geometrical configuration of solid surfaces is vital to achieving the Superhydrophobicity and to achieve Cassie-Baxter state the following two criteria need to be met: 1) Contact line forces overcome body forces of unsupported droplet weight and 2) The microstructures are tall enough to prevent the liquid that bridges microstructures from touching the base of the microstructures [1]. In this paper we discuss different measurements used to characterise/determine the superhydrophobic surfaces.Keywords: Wettability, contact angle, contact angle hysteresis, contact time, surface roughness, drag reduction measurements, morphology, surface friction, Reynolds number
Authors: Kharis Rakhimyanov, Konstantin Rakhimyanov, Anna Eryomina
Abstract: The efficiency of applying electrophysical impacts in technological methods of machine part cutting to a great extent depends on the understanding of the processes forming the basis of these impacts. As a rule a specific nature of these processes is characterized by their high intensity, locality of the impact and an impulse mode.The understanding of a certain process is necessary both for its efficient use in technological processes and for the development of new technologies based on the combination with other electrophysical impacts. The paper presents the results of mathematical modeling of deformation processes under ultrasonic frequency impulse plastic impact of a deformer on the surface layer of metals and alloys. Based on the mathematical modeling of the process of ultrasonic deformation of materials, operating parameters of the impact defining the field of application of this method are found. Quantitative relationships between basic characteristics of the deformation process and operating parameters of an ultrasonic impact are established.
Authors: Elena S. Gogina, Olga V. Yantsen, O. A. Ruzhitskaya
Abstract: The paper deals with the calculation of the contact time of waste water in the body of feed in the biofilter to determine the optimum settings.
Authors: Zuo Ying Zhang, Wan Li Zhang, Chi Xu
Abstract: A Mechanical model of impact and contact between the ball and re-circulating mechanism in ball screw was brought forward according to the Hertz contact model and classical impact theory, along with the joint relationship of re-circulating mechanism and nut taken into account. Then the formula of the impact force and contact time was induced, which the elastic coefficient of restitution was considering in contact time calculation. Moreover, a special test unit was designed for contact time measurement and the contact time was measured. The result indicates that the new model proposed in this paper is closer to the practical situation than the old model proposed in literature. Based on works mentioned above, the influence of impact angle, parameters of structure and material on impact force was analyzed by numerical simulation.
Authors: Ren Bo Xu, Li Shan Cui, Yan Jun Zheng
Abstract: The contact force during impact of a NiTi alloy was studied in this paper. The contact force and contact time during impact between a spherical impactor and the specimen at different impact velocity and temperature were measured in real time. The maximum contact force and contact time of the NiTi alloy in the martensite state increased and decreased respectively with increasing temperature. The maximum contact force of the NiTi alloy in the parent phase state showed a plateau with increasing impact velocity of the impactor.
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