The paper reports an experimental investigation of a newly proposed solar collector that integrates a closed-end pulsating heat pipe (PHP) and a compound parabolic concentrator (CPC).The PHP is used as an absorber due to its simple structure and high heat transfer capacity. The CPC has a concentration ratio of 3.4 and can be readily manufactured by three-dimensional printing. The CPC can significantly increase the incident solar irradiation intensity to the PHP absorber and also reduce the heat loss due to the decrease in the area of the hot surface. A prototype of the solar collector has been built, consisting of a PHP absorber bent by 4 mm diameter copper tube, CPC arrayed by 10×2 CPC units with the collection area of 300×427.6 mm 2 , a hot water tank and a glass cover. HFE7100 was utilized as the working fluid at a filling ratio of 40%. The operating characteristics and thermal efficiency of the solar collector were experimentally studied. The steady and periodic temperature fluctuations of the evaporation and condensation sections of the PHP absorber indicate that the absorber works well with a thermal resistance of about 0.26 ℃/W. It is also found that, as the main factor, the thermal performance of the collector decreases with increasing evaporation temperature. The collector apparently shows start-up, operational and shutdown stages at the starting and ending temperatures of 75 °C. When the direct normal irradiance is 800 W/m 2 , the instantaneous thermal efficiency of the solar collector can reach up to 50%.

The dynamic behaviors of methylcyclohexane (MCH) and perfluoro(methylcyc1ohexane) (PFMCH) liquids confined to porous silica glasses prepared by the sol-gel process are compared. The NMR spin-lattice relaxation times, T I , of the MCH and PFMCH liquids in porous silica glasses are reported as a function of pore size in the range from 24 to 96 A over the temperature range from -8 to 45 "C. The pore-size-dependent experimental TI data are analyzed in terms of a general expression obtained from our previous studies, UT1 = 1/Tlb + B/R + A/R*, where T l b is the relaxation time for bulk liquid, R is the average pore radius, and A and B are two parameters which indicate the relative strength of surface and topological effects on the observed NMR relaxation rates of confined liquids. On the basis of the surface enhancement values, TldTl,, where TI, is the relaxation time of the surface layer liquid, we conclude that the confined PFMCH molecules have a stronger interaction with the glass surface and thus exhibit more hindered molecular motions than the confined MCH molecules. In contrast, topological confinement plays a smaller role in affecting the translational diffusion of PFMCH molecules near the glass surface. In addition to the confinement studies, we have investigated the dynamic structure of bulk PFMCH by analyzing shear viscosity data in terms of the rough-hard-sphere model of liquids in a manner similar to our previous bulk liquid MCH study.

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Because of the microgravity environment of the space and mobility restriction by pressurized spacesuit, astronaut extravehicular operation is quite different from that in the ground. For ensuring high reliability of extravehicular operations, the astronauts need to do a great deal of training in simulated environments. A 3-dof of micro-gravity operation training system is designed in the paper, and the kinematics and dynamics of the interaction between the space station system and spacesuit system were simulated. Pressure and flow velocity distributions in the air orifice and air cavity were calculated by FLUENT. Experiments on the bearing capacity characteristic were carried out. The carrying capacities of the air bearing in different air pressures were achieved. Experiments validated the simulation analysis. The research provides the basis for the development of multi-degree of freedom space microgravity ground simulation technology, provides a basis for further development and application of flotation technology as well.

Based on pneumatic artificial muscle actuator (PMA) technology, a power assist device for the elbow joint actuated by a pair of antagonist muscles was designed. Dynamic models of the power assist device were established, driving characteristics of the device were simulated. The results show that the PMA complies with the requirements of the device, and the device can compensate the resistance caused by the spacesuit and the inertia forces by motion. Hence the device will be a great help for astronauts EVA operation. The research is used as a foundation for future development of power assist spacesuit.