Nickel phosphide catalysts supported on the TiO 2 ÀAl 2 O 3 composite oxide were successfully prepared by impregnation of nickel phosphate precursors followed by temperature-programmed reduction. The catalysts were characterized by X-ray diffraction, thermogravimetric analysis, IR spectroscopy, N 2 adsorption, and X-ray photoelectron spectroscopy. The catalytic activity was characterized in a fixed-bed reactor for hydrodesulfurization using a model liquid-feed dibenzothiophene, which contained 2000 mg/kg sulfur. Experimental results indicate that the TiO 2 ÀAl 2 O 3 composite support effectively prevents the formation of aluminum phosphates due to the strong interaction between phosphorus and γ-Al 2 O 3 , and it also shows strong interactions with Ni and P species on the surface, which is the main reason for the enhancement in hydrodesulfurization activity and stability. Among the Ni 2 P/TiO 2 ÀAl 2 O 3 samples tested, the catalyst at a Ni loading of 15 wt % showed the highest activity with a steady-state dibenzothiophene conversion of 99.9% at 613 K, 2.5 MPa, WHSV 3 h À1 , and volume ratio of hydrogen/oil of 450.

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In this paper, a conventional Strapdown Inertial Navigation System (SINS) alignment method on a disturbed base is analysed. A novel method with an attitude tracking idea is proposed for the rocking base alignment. It is considered in this method that the alignment algorithm should track the rocking base attitude real changes in the alignment process, but not excessively restrain disturbance. According to this idea, a rapid alignment algorithm is devised for the rocking base. In the algorithm, coarse alignment is carried out within 30 s in the inertial frame with alignment precision less than 2°, which meets Kalman filter linearization conditions well. Then a Kalman filter with ten state vectors and four measurement vectors is applied for the fine alignment to improve the capability of the algorithm in tracking the vehicle attitude. A turntable rotation experiment is carried out to validate the capability of the fine algorithm in tracing the large magnitude change during alignment. It is shown that the repeated alignment precision is about 0·04°by the alignment experiment on a rocking vehicle, with alignment time of 180 s. The Laser Strapdown Inertial Navigation System (LINS) ground navigation experiment suggests that the algorithm proposed by this paper can be satisfied without the need of high precision SINS alignment. K E Y WO R D S 1. SINS.2. Initial alignment. 3. Kalman filter. 4. Tracking.

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The high surface accuracy design of a cable-net antenna structure under the disturbance of the extremely harsh space environment requires the antenna to have good in-orbit adjustment ability for surface accuracy. A shape memory cable-net (SMC) structure is proposed in this paper and believed to be able to improve the in-orbit surface accuracy of the cable-net antenna. Firstly, the incremental stiffness equation of a one-dimensional bar element of the shape memory alloy (SMA) to express the relationship between the force, temperature and deformation was effectively constructed. Secondly, the finite element model of the SMC antenna structure incorporated the incremental stiffness equation of a SMA was established. Thirdly, a shape active adjustment procedure of surface accuracy based on the optimization method was presented. Finally, a numerical example of the shape memory cable net structure applied to the parabolic reflectors of space antennas was analyzed.