Papers by Keyword: High-Speed

Abstract: The performance prediction of High-speed railway bridges (HSRB) is vital to detect the behavior of bridges under different train’s speeds. This study aims to design a prediction model using the artificial neural network (ANN) to assess the performance of Yonjung high-speed bridge. A short-term health monitoring system is used to collect the behavior of bridge with different high-speed train’s speeds. The statistical analysis is utilized to evaluate the bridge under speeds 165 to 403 Km/h. The evaluation of bridge and prediction model showing that the bridge is safe, and the ANN is shown a good tool can be used to estimate a prediction model for the displacement of bridge girder.

Abstract: The paper describes an experimental determination of kinematic quantities using high-speed digital image correlation system. It deals with the analysis of minimal sampling frequency needed for correctly performed high-speed correlation analysis. The authors also describe the influence of cameras sampling frequency on the quality of the obtained results. Mentioned analysis was performed using a rotational object. For the purposes of the results comparison the data obtained from correlation system in a form of displacements in three mutually perpendicular directions were processed in Matlab and in the paper are depicted in a form of graphical visualizations.

Abstract: In the given work, the investigations have been directed to the creation of porous composite materials with MgO and B₄C ceramic filler. The laboratory technology of obtaining rods from the given materials has been developed. The experimental part of this work was carried out on ballistic set-ups with shaft-reactive and electrochemical technologies of throwing with the use of high-energy plastisol fuels with nanosize metallic fillers. Mathematical modeling of the behavior of materials under conditions of high-speed interaction was carried out in the framework of a porous elastoplastic medium according to different destruction mechanisms.

Abstract: In modern communication system, the spacing of channel becomes ever more finely. For communication equipment, it has made ​​high demands on the stability and accuracy of the frequency. Based on DDS technology, combined with the multiplier circuit, we developed a high-speed X-band frequency hopping source. Experimental results show that this frequency source is with excellent frequency stability and low phase noise.

Abstract: This paper introduces the working principle of ADN2841 and analyzes the main features and the typical application circuit of ADN2841. The laser communication transmission modulation circuit design for the 14 foot butterfly package directly modulated lasers is proposed, and according to the realization and debugging, we summarize the ADN2841 application experience and pay attention to the problem.

Abstract: Nickel-base superalloy GH4169 is a kind of alloy with high intensity, heat-stability and heat-fatigability, so that is often used to aerospace field, but which has poor machinability. The cutting force, plasticity deformation all present their particular characters which causes cutting vibration . The cutting vibration influence the surface roughness, the swing of the cutting force and tool wear. This article discusses the superalloy of GH4169 on the basis of cutting speed, cutting depth and feed per-tooth.

Abstract: Dynamometer has a extensive application in high-speed milling. The high frequency dynamometer is a kind of strain-gage dynamometer and produces a relation between the cutting force and voltage. And the relation can be expressed as a conversion matrix model which makes a great impact on the results of measurement. Taking into account cross-sensitivity and point effect at the same time, a new conversion matrix model for the high frequency dynamometer was established in order to improve the accuracy of dynamometer and the dynamometer has been subjected to calibration experiments to obtain conversion matrixes of the model. Finally, a series of high speed milling experiments were conducted. And the results obtained showed that the dynamometer by adopting the model could measure the cutting forces and have a higher accuracy.

Abstract: Cutting tool temperature is the main factor that directly affects tool wear and tool life. In this paper we developed temperature model of tool insert during slot milling process, constructed by a combination of cutting time model and non-cutting model. A set of experiments are designed and carried out to obtain cutting induced temperatures at different cutting speeds during slot milling of AISI H13 steel. Experiments results indicate that tool insert temperature increases first and then decreases as the cutting speed grows, and a critical cutting speed for the tool insert temperature exists during slot milling of AISI H13 steel. Some possible reasons for the drop of tool insert temperature are proposed and discussed, and they are decreased heat flux into tool insert and increased heat convection coefficient.

Abstract: One of the most important factors which influence on the dynamical behavior of the high-speed feed drives for CNC machines is position loop gain or Kv factor. It directly influences the contouring accuracy of the CNC machines. Usually position loop gain is experimentally tuned on the already assembled CNC machines. This paper gives one approach towards its analytical calculation. The difference between analytical calculated and experimentally obtained Kv-factor is smaller than 5%, which is completely acceptable.

Abstract: Polycrystalline ڂ˽SiC thick film with mm-scaled thickness was deposited on a graphite substrate using a gaseous mixture of SiCl₄ + CH₄ and H₂ at temperatures ranging from 1573 to 1823 K by chemical vapor deposition. Effect of deposition temperature (T_dep) on deposition rate, surface morphology and preferred orientation has been studied. The preferred orientation changed from <111> to <110> with increasing T_dep. The maximum deposition rate (R_dep) of 1125 ڌ̽˰̸⁻¹ has been obtained. The surface morphology has changed from six-fold pyramid to five-fold facet with increasing T_dep.