Caffeine nucleation induction times were measured at 30 °C and 40 °C in water and ethanol solvents employing laser light absorption technique. Supersaturation concentrations and liquid/solid phase surface te...Caffeine nucleation induction times were measured at 30 °C and 40 °C in water and ethanol solvents employing laser light absorption technique. Supersaturation concentrations and liquid/solid phase surface tensions were calculated from crystallization induction times using classic homogeneous nucleation theory. Induction time and surface tension decreased at higher temperature.展开更多
Reliable evaluations of a noise jammer's effectiveness are necessary to properly design, manufacture, and operate one, so it is important to have an evaluation model. Based on their characteristics and principles,...Reliable evaluations of a noise jammer's effectiveness are necessary to properly design, manufacture, and operate one, so it is important to have an evaluation model. Based on their characteristics and principles, relevant factors were classified in terms of their contribution to a unit's effectiveness. In this way an evaluation index system was established. In the proposed mathematical model a noise jammer is analyzed by combining the model of system effectiveness with the method of analytic hierarchical process. A simulation of underwater acoustic countermeasures was used to test the rationality and feasibility of the model. The results showed that this model is an effective way to solve the challenge of evaluating the effectiveness of non-offensive weapons under single working phase.展开更多
In this work, the wing tip vortex structure behind a NACA 0015 airfoil with and without small flaps was studied using a Partical Image Velocimetry （PIV） system. The experiment was carried out in a low speed wind tun...In this work, the wing tip vortex structure behind a NACA 0015 airfoil with and without small flaps was studied using a Partical Image Velocimetry （PIV） system. The experiment was carried out in a low speed wind tunnel with a test section of 0.5 m x 0.5 m. The Reynolds number （Re）, defined by the chord length of the wing （C）, was 8.1 x 104. The angle of attack was fixed at 10~. The PIV measurements were made from 0 to 2C, measured from the trailing edge of the model. The dihedral angle of three flaps was -15~, 0~ and 15~, respectively. Compared with the clean airfoil, the one with three flaps significantly changed the wing tip vortex structure, the vorticity and the core of the wing tip vortex. The occurrence of three flaps decreased the gradient of pressure on the two sides of the wing tip, which depressed wing tip vortex formation to some extent. Vortices shed from three flaps influence the evolution of the wingtip vortex generated by the base airfoil. The interaction of those vortices resulted in a weakening of the wing tip vortex.展开更多
A principle of generating the nonlinear large-amplitude internal wave in a stratified fluid tank with large cross-section is pro- posed according to the ＇jalousie＇ control mode. A new wave-maker based on the princip...A principle of generating the nonlinear large-amplitude internal wave in a stratified fluid tank with large cross-section is pro- posed according to the ＇jalousie＇ control mode. A new wave-maker based on the principle was manufactured and the experi- ments on the generation and evolution of internal solitary wave were conducted. Both the validity of the new device and ap- plicability range of the KdV-type internal soliton theory were tested. Furthermore, a measurement technique of hydrodynamic load of internal waves was developed. By means of accurately measuring slight variations of internal wave forces exerted on a slender body in the tank, their interaction characteristics were determined. It is shown that through establishing the similarity between the model scale in the stratified fluid tank and the full scale in the numerical simulation the obtained measurement re- suits of internal wave forces are confirmed to be correct.展开更多
The shock temperatures of water under 35-50 GPa are firstly measured by the optical pyrometry technique. Cν is a constant below 51 GPa (Cν=7.07R), and increases with the temperature above 51 GPa (Cν=(5.76+3.84×...The shock temperatures of water under 35-50 GPa are firstly measured by the optical pyrometry technique. Cν is a constant below 51 GPa (Cν=7.07R), and increases with the temperature above 51 GPa (Cν=(5.76+3.84×10-4T)R). From our calculation, the dissociation has little effect on Cν. But the electron is essential to the Cν calculation.展开更多
We describe a fiber optic hydrophone array system that could be used for underwater acoustic surveillance applications （e.g. military, counter terrorist, and customs authorities in protecting ports and harbors）, off...We describe a fiber optic hydrophone array system that could be used for underwater acoustic surveillance applications （e.g. military, counter terrorist, and customs authorities in protecting ports and harbors）, offshore production facilities or coastal approaches as well as various marine applications. In this paper, we propose a new approach to underwater sonar systems using the voltage-controlled liquid crystals and simple multiplexing method. The proposed method permits measurement of sound under water at multiple points along an optical fiber using the low cost components and standard single mode fiber, without complex interferometric measurement techniques, electronics or demodulation software.展开更多
文摘Caffeine nucleation induction times were measured at 30 °C and 40 °C in water and ethanol solvents employing laser light absorption technique. Supersaturation concentrations and liquid/solid phase surface tensions were calculated from crystallization induction times using classic homogeneous nucleation theory. Induction time and surface tension decreased at higher temperature.
基金Supported by the National Key Laboratory Foundation under Grant No. 9140C2304080607.
文摘Reliable evaluations of a noise jammer's effectiveness are necessary to properly design, manufacture, and operate one, so it is important to have an evaluation model. Based on their characteristics and principles, relevant factors were classified in terms of their contribution to a unit's effectiveness. In this way an evaluation index system was established. In the proposed mathematical model a noise jammer is analyzed by combining the model of system effectiveness with the method of analytic hierarchical process. A simulation of underwater acoustic countermeasures was used to test the rationality and feasibility of the model. The results showed that this model is an effective way to solve the challenge of evaluating the effectiveness of non-offensive weapons under single working phase.
基金supported by the National Natural Science Foundation of China(Grant No. 10642002)
文摘In this work, the wing tip vortex structure behind a NACA 0015 airfoil with and without small flaps was studied using a Partical Image Velocimetry （PIV） system. The experiment was carried out in a low speed wind tunnel with a test section of 0.5 m x 0.5 m. The Reynolds number （Re）, defined by the chord length of the wing （C）, was 8.1 x 104. The angle of attack was fixed at 10~. The PIV measurements were made from 0 to 2C, measured from the trailing edge of the model. The dihedral angle of three flaps was -15~, 0~ and 15~, respectively. Compared with the clean airfoil, the one with three flaps significantly changed the wing tip vortex structure, the vorticity and the core of the wing tip vortex. The occurrence of three flaps decreased the gradient of pressure on the two sides of the wing tip, which depressed wing tip vortex formation to some extent. Vortices shed from three flaps influence the evolution of the wingtip vortex generated by the base airfoil. The interaction of those vortices resulted in a weakening of the wing tip vortex.
基金supported by the National Natural Science Foundation of China(Grant No.11072267)the National High Technology Research and Development Program of China(Grant No.2008AA09Z316)the Pre-Research Foundation of PLA University of Science&Technology(Grant No.KYLYZLXY1202)
文摘A principle of generating the nonlinear large-amplitude internal wave in a stratified fluid tank with large cross-section is pro- posed according to the ＇jalousie＇ control mode. A new wave-maker based on the principle was manufactured and the experi- ments on the generation and evolution of internal solitary wave were conducted. Both the validity of the new device and ap- plicability range of the KdV-type internal soliton theory were tested. Furthermore, a measurement technique of hydrodynamic load of internal waves was developed. By means of accurately measuring slight variations of internal wave forces exerted on a slender body in the tank, their interaction characteristics were determined. It is shown that through establishing the similarity between the model scale in the stratified fluid tank and the full scale in the numerical simulation the obtained measurement re- suits of internal wave forces are confirmed to be correct.
基金supported by the Auspices of the Science Foundation (Grant No. 10874141)
文摘The shock temperatures of water under 35-50 GPa are firstly measured by the optical pyrometry technique. Cν is a constant below 51 GPa (Cν=7.07R), and increases with the temperature above 51 GPa (Cν=(5.76+3.84×10-4T)R). From our calculation, the dissociation has little effect on Cν. But the electron is essential to the Cν calculation.
文摘We describe a fiber optic hydrophone array system that could be used for underwater acoustic surveillance applications （e.g. military, counter terrorist, and customs authorities in protecting ports and harbors）, offshore production facilities or coastal approaches as well as various marine applications. In this paper, we propose a new approach to underwater sonar systems using the voltage-controlled liquid crystals and simple multiplexing method. The proposed method permits measurement of sound under water at multiple points along an optical fiber using the low cost components and standard single mode fiber, without complex interferometric measurement techniques, electronics or demodulation software.
