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Objective To optimize a self-emulsifying drug delivery system (SEDDS) formulation for psoralen and isopsoralen (PSO and IPSO) isolated from Psoraleae Fructus. Methods A D-optimal design was used to investigate the influence of oil percentage, surfactant percentage and cosurfactant percentage on several properties of SEDDS including particle size, polydispersity, equilibrium solubility, in situ intestine absorption rate and intestinal permeability. Furthermore, the desirability function approach was applied to obtain the optimal formulation for the system. Results The oil percentage, surfactant percentage and cosurfactant percentage were optimized to be 53.6%, 35.7% and 10.7%, respectively, which means the model is available. Conclusions The D-optimal design is valuable to optimize the SEDDS formulation and understand formulation compositions’ functions on SEDDS properties.

Preliminary design of offshore wind turbines requires high precision simplified methods for the analysis of the system fundamental frequency. Based on the Rayleigh method and Lagrange’s Equation, this study establishes a simple formula for the analysis of system fundamental frequency in the preliminary design of an offshore wind turbine with a monopile foundation. This method takes into consideration the variation of cross-section geometry of the wind turbine tower along its length, with the inertia moment and distributed mass both changing with diameter. Also the rotational flexibility of the monopile foundation is mainly considered. The rigid pile and elastic middle long pile are calculated separately. The method is validated against both FEM analysis cases and field measurements, showing good agreement. The method is then used in a parametric study, showing that the tower length Lt, tower base diameter d0, tower wall thickness δt, pile diameter db and pile length Lb are the major factors influencing the fundamental frequency of the offshore wind turbine system. In the design of offshore wind turbine systems, these five parameters should be adjusted comprehensively. The seabed soil condition also needs to be carefully considered for soft clay and loose sand.

New types of synthetic municipal solid wastes (MSWs) were developed, exhibiting engineering characteristics similar to those of real MSWs at different states of degradation in terms of total unit weight, void ratio, water content, compressibility, permeability, stress–strain relationship, and shear strength. Using these synthetic MSWs, several centrifuge model tests on the stability of geosynthetics-lined landfills with rising water levels were performed. The test results revealed the developing processes of MSW landfill failures induced by rising water levels. In most tests, a continuous slide occurred once a critical water level was attained. The ratio of critical water level and landfill height was 0.75–0.92 for present model tests using fresh or partly degraded synthetic MSWs with landfill slope ratio of 1:1–1:3, increasing with the increases of MSW degradation states and decreases of the slope ratio. An engineered berm increased the critical water level by 1.3%–9.5%. The landfills without an engineered berm tended to slide along the bottom liner; however, for normal landfills with an engineered berm and a slope ratio of 1:3, penetrating cracks developed when the failures occurred. These results provide a good reference for water level and stability control of the landfill, and the construction of an engineered berm is suggested to improve the stability of these landfills.

This work presents the latest research & development achievement of spaceborne GPS receiver at Tsinghua Space Center (TSC). Based on the commercial-off-the-shelf components released by Zarlink Semiconductor, TSC has completed the development of spaceborne GPS receiver for the nanosatellite project. The GPS receiver features high dynamics at low power, mass and cost, which makes it suitable to provide positioning, velocity and time for micro/nanosatellites especially. A series of recent tests have validated its capability. Some new improvements have been made to fulfill the requirement of the coming space mission.

This paper presents the research & development of spaceborne GPS receiver at Tsinghua Space Center (TSC). Based on the commercial-off-the-shelf components released by Zarlink Semiconductor, TSC has completed the development of spaceborne GPS receiver for the nanosatellite project. The GPS receiver features high dynamics at low power, mass and cost, which makes it suitable to provide positioning, time and velocity for micro/nanosatellites. TSC is ongoing into the R&D of another miniature spaceborne GPS receiver. The new design will be more compact in the power, mass and size while keeping the original features. This GPS receiver is intended for the differential measurement in microsatellite formation flying.