The principle of a new type of no-pulsation continuous rotary electro-hydraulic servomotor applied to simulators is introduced. LuGre friction model was analyzed. The identification method of LuGre parameters was prop...The principle of a new type of no-pulsation continuous rotary electro-hydraulic servomotor applied to simulators is introduced. LuGre friction model was analyzed. The identification method of LuGre parameters was proposed, and the measures to compensate the effect of friction forces were given. A friction torque model for the new rotary motor was proposed. The low-speed response and step response of the motor were studied experimentally. Experimental results proved that using friction compensation could eliminate stick-slip motion at the low speed, which makes the servomotor applicable to simulators.展开更多
Trans-sobrerol （Sob） and 8-p-menthen-1,2-diol （Limo-diol） are the primary products in the atmospheric oxidation of α-pinene and limonene, respectively. Because of their low volatility, they associate more likely ...Trans-sobrerol （Sob） and 8-p-menthen-1,2-diol （Limo-diol） are the primary products in the atmospheric oxidation of α-pinene and limonene, respectively. Because of their low volatility, they associate more likely to the liquid particles in the atmosphere, where they are subject to the aqueous phase oxidation by the atmospheric oxidants. In this work, through experimental and theoretical study, we first provide the rate constants of Sob and Limo-diol reacting with hydroxyl radical （.OH） in aqueous solution at room temperature of 3044-3 K and 1 atm pressure, which are （3.05±0.5）×10 9 and （4.57±0.2）×10 9 L/（mol.s）, respectively. Quantum chemistry calculations have also been employed to demonstrate the solvent effect on the rate constants in aqueous phase and the calculated results agree well with the measurements. Some reaction products have been identified based on liquid chromatography combined with mass spectroscopy and theoretical calculations.展开更多
The normal hypervelocity impact of an Al-thin plate by an Al-sphere was numerically simulated by using the adaptive smoothed particle hydrodynamics (ASPH) method. In this method, the isotropic smoothing algorithm of s...The normal hypervelocity impact of an Al-thin plate by an Al-sphere was numerically simulated by using the adaptive smoothed particle hydrodynamics (ASPH) method. In this method, the isotropic smoothing algorithm of standard SPH is replaced with anisotropic smoothing involving ellipsoidal kernels whose axes evolve automatically to follow the mean particle spacing as it varies in time, space, and direction around each particle. Using the ASPH, the anisotropic volume changes under strong shock condition are captured more accurately and clearly. The sophisticated features of meshless and Lagrangian nature inherent in the SPH method are kept for treating large deformations, large inhomogeneities and tracing free surfaces in the extremely transient impact process. A two-dimensional ASPH program is coded with C++. The developed hydrocode is examined for example problems of hypervelocity impacts of solid materials. The results obtained from the numerical simulation are compared with available experimental ones. Good agreement is observed.展开更多
Small reactors have become a new hotspot of international nuclear energy research.The nuclear heating reactor(NHR)technology developed by Tsinghua University is an important multipurpose small reactor solution with fe...Small reactors have become a new hotspot of international nuclear energy research.The nuclear heating reactor(NHR)technology developed by Tsinghua University is an important multipurpose small reactor solution with features such as high integration,modular design and full power natural circulation.A new small reactor based on the existing NHR-200 reactor was developed by the Institute of Nuclear and New Energy Technology of Tsinghua University.A full-scale natural circulation test loop with the same operating parameters as the actual reactor was built in order to experimentally validate the natural circulation ability of the reactor primary loop and heat-transfer ability of fuel assemblies and heat exchangers.Corresponding results are given in detail,including parameter validation of the reactor primary loop,flow rules of the natural circulation and heat-transfer coefficients of heaters and heat exchangers,which can be directly used in the actual reactor as a reference for optimization design.Finally,a characteristic parameter k is proposed to represent the natural circulation ability of a system.By using the new data arrangement method in the form of parameter k,comprehensive experimental results of the natural circulation can be represented by a simple integrated expression.The work in this paper is of importance in broadening application fields and pushing forward commercialization of the NHR type reactors.展开更多
文摘The principle of a new type of no-pulsation continuous rotary electro-hydraulic servomotor applied to simulators is introduced. LuGre friction model was analyzed. The identification method of LuGre parameters was proposed, and the measures to compensate the effect of friction forces were given. A friction torque model for the new rotary motor was proposed. The low-speed response and step response of the motor were studied experimentally. Experimental results proved that using friction compensation could eliminate stick-slip motion at the low speed, which makes the servomotor applicable to simulators.
基金This work was supported by the National Natural Science Foundation of China （No.21177041 and No.21107026）, the Fundamental Research Funds for the Central Universities （No.2013ZZ0073）, and the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry.
文摘Trans-sobrerol （Sob） and 8-p-menthen-1,2-diol （Limo-diol） are the primary products in the atmospheric oxidation of α-pinene and limonene, respectively. Because of their low volatility, they associate more likely to the liquid particles in the atmosphere, where they are subject to the aqueous phase oxidation by the atmospheric oxidants. In this work, through experimental and theoretical study, we first provide the rate constants of Sob and Limo-diol reacting with hydroxyl radical （.OH） in aqueous solution at room temperature of 3044-3 K and 1 atm pressure, which are （3.05±0.5）×10 9 and （4.57±0.2）×10 9 L/（mol.s）, respectively. Quantum chemistry calculations have also been employed to demonstrate the solvent effect on the rate constants in aqueous phase and the calculated results agree well with the measurements. Some reaction products have been identified based on liquid chromatography combined with mass spectroscopy and theoretical calculations.
文摘The normal hypervelocity impact of an Al-thin plate by an Al-sphere was numerically simulated by using the adaptive smoothed particle hydrodynamics (ASPH) method. In this method, the isotropic smoothing algorithm of standard SPH is replaced with anisotropic smoothing involving ellipsoidal kernels whose axes evolve automatically to follow the mean particle spacing as it varies in time, space, and direction around each particle. Using the ASPH, the anisotropic volume changes under strong shock condition are captured more accurately and clearly. The sophisticated features of meshless and Lagrangian nature inherent in the SPH method are kept for treating large deformations, large inhomogeneities and tracing free surfaces in the extremely transient impact process. A two-dimensional ASPH program is coded with C++. The developed hydrocode is examined for example problems of hypervelocity impacts of solid materials. The results obtained from the numerical simulation are compared with available experimental ones. Good agreement is observed.
基金supported by the National S&T Major Project(Grant No.ZX06901)the National Natural Science Foundation of China(Grant No.11072131)
文摘Small reactors have become a new hotspot of international nuclear energy research.The nuclear heating reactor(NHR)technology developed by Tsinghua University is an important multipurpose small reactor solution with features such as high integration,modular design and full power natural circulation.A new small reactor based on the existing NHR-200 reactor was developed by the Institute of Nuclear and New Energy Technology of Tsinghua University.A full-scale natural circulation test loop with the same operating parameters as the actual reactor was built in order to experimentally validate the natural circulation ability of the reactor primary loop and heat-transfer ability of fuel assemblies and heat exchangers.Corresponding results are given in detail,including parameter validation of the reactor primary loop,flow rules of the natural circulation and heat-transfer coefficients of heaters and heat exchangers,which can be directly used in the actual reactor as a reference for optimization design.Finally,a characteristic parameter k is proposed to represent the natural circulation ability of a system.By using the new data arrangement method in the form of parameter k,comprehensive experimental results of the natural circulation can be represented by a simple integrated expression.The work in this paper is of importance in broadening application fields and pushing forward commercialization of the NHR type reactors.
