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Effects of polyphosphoric acid modified asphalt on the low-temperature cracking of asphalt mixtures 被引量:3
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作者 丁海波 张华 王郴平 《Journal of Southeast University(English Edition)》 EI CAS 2016年第2期215-218,共4页
In order to determine whether polyphosphoric acid (PPA) can partially or completely substitute styrene-butadiene- styrene (SBS) modifier while it does not adversely affect the resistance to thermal cracking of the... In order to determine whether polyphosphoric acid (PPA) can partially or completely substitute styrene-butadiene- styrene (SBS) modifier while it does not adversely affect the resistance to thermal cracking of the asphalt mixture, the low- temperature fracture properties of the PPA modified mixtures are evaluated and compared to the SBS modified mixtures. First, laboratory compacted test samples were tested by the indirect tensile test (IDT) and the newly developed fracture testing protocol, named as disk-shaped compact tension (DCT). Then, the effects of the test temperature and air-void ratio on the low-temperature fracture properties of asphalt mixtures were analyzed. The results show that the fracture resistance of the PPA modified mixtures is worse than that of the SBS modified mixtures. However, for those modified mixtures that use the PPA substituting part of the SBS modifier, a relatively low-temperature fracture resistance can be obtained compared with the mixture only using the SBS modifier. 展开更多
关键词 asphalt mixture low temperature polyphosphoricacid disk-shaped compact tension
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Simplified circuit model of disk-shaped traveling wave ultrasonic motor 被引量:1
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作者 CHU Xiangcheng LI Longtu(The State Key Laboratory of New Ceramics and Fine Processing, Dept. of Materials Science and Engineering, Tsinghua University Beijing 100084)CHEN Zaili(Faculty of Electromachine Engineering, Harbin Institute of Technology Harbin 1 《Chinese Journal of Acoustics》 2002年第3期211-224,共14页
This paper presents a method of establishing simplified equivalent circuit model of traveling wave ultrasonic motor by using 1/2 wavelength stator with the similar vibration characteristics. Combined with the vibratio... This paper presents a method of establishing simplified equivalent circuit model of traveling wave ultrasonic motor by using 1/2 wavelength stator with the similar vibration characteristics. Combined with the vibration mode characteristics of the composite stator, the method utilizes Hamilton principle to obtain precise solution of the simplified equivalent circuit. The model shows the mechanism of ultrasonic motor, considering the influence of non-axisymmetric vibration mode, tooth outline, anisotropy of PZT (Piezoelectric ceramic), etc. With this method, various electric parameters corresponding to different vibration modes, such as static capacitance, dynamic capacitance, dynamic inductance, dynamic resistance, equivalent input impedance, etc., can be solved. Experiments show good agreement with theoretical results. 展开更多
关键词 WAVE Simplified circuit model of disk-shaped traveling wave ultrasonic motor mode PZT
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Certain Aspects of the Gravitational Field of a Disk
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作者 Jonathan D. Weiss 《Applied Mathematics》 2018年第12期1360-1377,共18页
There are at least two reasons why one would study the gravitational field of a disk. The first is that many astronomical objects, such as spiral galaxies like the Milky Way, are disk-like. The second is that the fiel... There are at least two reasons why one would study the gravitational field of a disk. The first is that many astronomical objects, such as spiral galaxies like the Milky Way, are disk-like. The second is that the field of a disk is interesting, particularly when compared to that of a spherical, or near-spherical, object, which is much easier to analyze because of its high degree of symmetry. It is hoped that this study will augment previous work on this subject. The aspects presented in this paper are as follows: 1) both the radial and vertical gravitational fields of a thin disk within the plane of the disk and above it;2) a comparison of some of the field results obtained by Lass and Blitzer (1983) involving elliptic integrals to those obtained by a standard numerical integration, now available online, and separately through the use of Legendre polynomials;3) the logarithmic divergence of the radial field at the edge of a thin disk;4) the fields in the plane of a disk containing a central hole, particularly within the hole, such as the rings of Saturn;5) circular orbits within the plane of a single disk and half way between two disks, and their stability;6) the escape velocity at a point within the Milky Way, particularly at the position of the solar system and without any added, or subtracted, orbital effects around the galactic center;and 7) the radial field at the circular edge of a disk of finite thickness. 展开更多
关键词 disk-shaped MASS GRAVITATIONAL EFFECTS of a disk-shaped MASS Calculational Techniques of SUCH GRAVITATIONAL EFFECTS
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Computational analysis of vibration modes of disk-shaped piezoelectric traveling wave motors
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作者 CHU Xiangcheng LI Longtu(The State Key Laboratory of New Ceramics and Fine Processing, Dept. of Materials Science and Engineering, Tsinghua University Beijing 100084)CHEN Zaili(Faculty of Electromachine Engineering, Harbin Institute of Technology Harbin 1 《Chinese Journal of Acoustics》 2002年第3期201-210,共10页
According to Kirchhoff-Love's assumptions, this paper establishes linear system of equations for solving eigen frequency constant and corresponding mode shape. Using engineer-ing and numerical analysis software Ma... According to Kirchhoff-Love's assumptions, this paper establishes linear system of equations for solving eigen frequency constant and corresponding mode shape. Using engineer-ing and numerical analysis software Matlab5.2 and method of coefficient determinant searching arithmetic, eigen frequency constant and mode shape of the stator with i.d./ o.d. ratio of 0.1, 0.3, 0.35, 0.6 and different vibration modes are accurately solved and analyzed. By means of Newton interpolation method, contributions of transverse deflection amplitude and vibration energy corresponding to various modes are determined. This paper offers a valid theoretical foundation for the optimum design of the stator of disk-shaped ultrasonic motors. Furthermore, according to results of numerical analysis, several choosing principles of vibration modes are summarized. 展开更多
关键词 WAVE MODE Computational analysis of vibration modes of disk-shaped piezoelectric traveling wave motors
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