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For the monthly spherical harmonic coefficients (SHCs) from GRACE, a method using empirical orthogonal function (EOF) and multi-channel singular spectrum analysis (MSSA) is presented to effectively reduce its dimension and remove its strip noise. The dynamic changing of the SHCs is analyzed, and the corresponding changing model is then constructed. The significant annual term and long term trend have been found in the discrete SHCs, which account for 50.6% and 77.4% (after the annual term has been deducted) of the total variance, respectively. The nonlinear model, which constructed from long term trend and annual term, can perfectly reflect the dynamic changing of the SHCs and its inversion results. And the fitting standard deviation of the equivalent water height on grids over global land areas is between 0.3 cm and 14.0 cm, and the average standard deviation is 1.8 cm. This study can provide valuable implications for the research on the parameter changing characteristics of gravity field and geodynamics.

Additional file 1.

Chemical mechanical polishing (CMP) of GaN(0001) with a H2O2-SiO2-based slurry is investigated in this paper. The result shows that an atomically flat surface with a roughness of 0.065 nm is obtained after polishing. Compared with a SiO2-based slurry, the H2O2-SiO2-based slurry can realize a higher material removal rate (MRR) and a better surface quality with less scratches. The pH value mainly affects the mean particle size of SiO2 and the chemical environment of the corrosion reaction with H2O2, resulting in different MRRs. An off-site auxiliary polishing method is employed along with the H2O2-SiO2-based polishing system using ultraviolet light to shine the outlet of slurry in order to catalyze the production of substance for oxidation, and it is proved to be efficient by improving the MRR to 103 nm/h. Physical and mathematic removal models are proposed to describe the removal mechanism of GaN CMP.

As the main part of the “central mountain system” in the continent of China, the Qinling, Qilian and Kunlun orogenic belts have been comprehensively and deeply studied since the 1970s and rich fruits have been reaped. However, these achievements were mostly confined to an individual orogenic belt and the study of the mutual relationship among the three orogenic belts was obliged to depend on comparative studies. Different views were produced therefrom. The material composition and structural features of the junction region show that there are several epicontinental and intracontinental transform faults developed in different periods. Restricted by these transform faults, the large-scale lateral movements and, as a consequence, complicated magmatism and tectonic deformation took place in the orogenic belts. According to these features, the authors put forward a three-stage junction and evolution model and point out that there is not a single junction zone traversing from west to east but that the three orogenic belts have been joined progressively by the epicontinental and intracontinental transform faults.

The status of the IMP (Institute of Modern Physics) mass separator facility on-line to the heavy ion accelerator HIRFL in Lanzhou is described. The results for off-line and on-line tests as well as the research program are reported.

A study on smart foam for passive–active underwater sound reduction in sound pulse tube is presented. The smart foam consists of cylindrically curved sections of PVDF film embedded in polyurethane acoustic foam forming a thin, compact arrangement. The device is designed to reduce sound by the simultaneous action of the passive absorption of the foam (effective at high frequencies) and the active input of the PVDF element driven by an oscillating electrical input(effective at low frequencies). A digital time delay & feed-forward control system has been developed and severs for the smart foam control system. The concept of smart foam control system is that of an open-loop velocity feedback between sensors and actuator.

A new ISOL facility has been constructed for on-line use with the heavy-ion accelerator HIRFL in Lanzhou. The focal principle of ISOLDE-type separators is modified by including a quadrupole doublet lens in front of the magnet. The mass spectra of Ar and Xe isotopes were measured with a scanner inside the collection chamber in an off-line test. The resolving power is equal to 700–1200 by only using a single einzel lens.