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EN
The HY-2A satellite is the first ocean dynamic environment monitoring satellite of China. Centimeter-level radial accuracy is a fundamental requirement for its scientific research and applications. To achieve this goal, we designed the strategies of precise orbit determination (POD) in detail. To achieve the relative optimal orbit for HY-2A, we carried out POD using DORIS-only, SLR-only, and DORIS + SLR tracking data, respectively. POD tests demonstrated that the consistency level of DORIS-only and SLR-only orbits with respect to the CNES orbits were about 1.81 cm and 3.34 cm in radial direction in the dynamic sense, respectively. We designed 6 cases of different weight combinations for DORIS and SLR data, and found that the optimal relative weight group was 0.2 mm/s for DORIS and 15.0 cm for SLR, and RMS of orbit differences with respect to the CNES orbits in radial direction and three-dimensional (3D) were 1.37 cm and 5.87 cm, respectively. These tests indicated that the relative radial and 3D accuracies computed using DORIS + SLR data with the optimal relative weight set were obviously higher than those computed using DORIS-only and SLR-only data, and satisfied the requirement of designed precision. The POD for HY-2A will provide the invaluable experience for the following HY-2B, HY-2C, and HY-2D satellites.
EN
A new three-step synthetic method was designed to prepare 2,6-diamino- 3,5-dinitropyrazine 1-oxide (LLM-105) with an overall yield of 43.5%, using iminodiacetonitrile, triethylamine and hydroxylamine hydrochloride as the starting materials, and involved nitrosylation, cyclization and nitration. The structure of LLM-105 was characterized by FTIR, 1H NMR spectroscopy and elemental analysis. The crucial factors and mechanism of the cyclization were explored. Thermal decomposition, mechanical sensitivity and the purity of the LLM-105 were determined by TG-DTA, an impact sensitivity instrument and high performance liquid chromatography (HPLC) respectively. The results showed that LLM-105 synthesised via 2,6-diamino-3,5-dinitropyrazine (ANPZ) was less sensitive to impact, but the LLM-105 synthesized by the new method had some obvious advantages in terms of purity, security and production costs. Moreover, the LLM-105 synthesized by this new method can be initiated reliably without recrystallization.
EN
We use GRACE gravity data released by the Center for Space Research (CSR) and the Groupe de Recherches en Geodesie Spatiale (GRGS) to detect the water storage changes over the Tibetan Plateau (TP). A combined filter strategy is put forward to process CSR RL05 data to remove the effect of striping errors. After the correction for GRACE by GLDAS and ICE-5G, we find that TP has been overall experiencing the water storage increase during 2003-2012. During the same time, the glacier over the Himalayas was sharply retreating. Interms of linear trends, CSR’s results derived by the combined filter are close to GRGS RL03 with the Gaussian filter of 300-km window. The water storage increasing rates determined from CSR’s RL05 products in the interior TP, Karakoram Mountain, Qaidam Basin, Hengduan Mountain, and middle Himalayas are 9.7, 6.2, 9.1, –18.6, and –20.2 mm/yr, respectively. These rates from GRGS’s RL03 products are 8.6, 5.8, 10.5, –19.3 and –21.4 mm/yr, respectively.
EN
A new high energy, low sensitivity material N,N,-bis(3-aminofurazan- 4-yl)-4,4´-diamino-2,2´,3,3´,5,5´,6,6´-octanitroazobenzene (BAFDAONAB) was synthesized from 4-chlorobenzoic acid and diaminofurazan. The structure of BAFDAONAB was characterized by FT-IR, NMR and Elemental Analyses and its purity was determined by HPLC. The optimized structure and thermodynamic parameters were obtained at the DFT- B3LYP/6-31+G** theoretical level. Its detonation properties were also predicted by the formulae of Kamlet-Jacobs and the Monte-Carlo method. The results show that the density, heat of formation, detonation velocity, detonation pressure, impact sensitivity and purity were 1.93 g/cm3, 4487.44 kJ/mol, 9.01 km/s, 35.03 GPa, 63 cm and 99.3%, respectively. In addition, the compound was an insensitive high explosive which could meet the requirements of high energetic materials.
EN
Amorphous alloys or metallic glasses have attracted significant interest in the materials science and engineering communities due to their unique physical, mechanical, and chemical properties. The viscous flow of amorphous alloys exhibiting high strain rate sensitivity and homogeneous deformation is considered to be an important characteristic in thermoplastic forming processes performed within the supercooled liquid region because it allows superplastic-like deformation behavior. Here, the correlation between the superheated liquid fragility, and the onset temperature of crystallization for Al-based alloys, is investigated. The activation energy for viscous flow of the liquid is also investigated. There is a negative correlation between the parameter of superheated liquid fragility and the onset temperature of crystallization in the same Al-based alloy system. The activation energy decreases as the onset temperature of crystallization increases. This indicates that the stability of a superheated liquid can affect the thermal stability of the amorphous alloy. It also means that a liquid with a large superheated liquid fragility, when rapidly solidified, forms an amorphous alloy with a low thermal stability.
EN
A rapid method has been used for simultaneous identification of both hydrophilic and lipophilic compounds from Radix Salviae Miltiorrhizae (RSM, the root of Salvia miltiorrhiza BGE.) by ultra-performance liquid chromatography/quadrupole time-offlight mass spectrometry (UPLC/Q-TOF-MS). A total of 58 compounds extracted by methanol were detected and tentatively identified within 20 min, including hydrophilic phenolics, lipophilic diterpenoids, a verbascose, and several organic acids. These compounds were separated on an Acquity UPLC BEH C18 column and identified based on tandem mass spectrometry (MS/MS) fragmentation patterns under the positive and negative ion modes, respectively. Among them, micranthin B and 9-oxo-10E,12Zoctadecadienoic acid were reported in RSM for the first time. Their fragmentation patterns in electrospray ionization (ESI)—MS/MS spectra were first investigated by matching their accurate molecular masses. This contribution presented one of the first reports on the analysis of hydrophilic phenolics and lipophilic diterpenoids from Radix Salviae Miltiorrhizae using UPLC/Q-TOF-MS. The results demonstrated that UPLC/Q-TOF-MS method could be applied to rapidly and expediently describe and provide comprehensive chemical information for simultaneous analysis of two different polar components in RSM.
EN
The ongoing warming in the Qinghai-Tibetan Plateau leads to changes in ecosystem processes while the responses of soil and vegetation are not well understand. Thus, we used infrared radiators to carry out experimental warming from July 2010 to August 2011 in an alpine meadow on the Plateau (about 4630 m above sea level) to research the responses of environmental factors and vegetation characteristics to short-term warming (1 year). The experimental design was a block design consisting of five replications and included three treatment levels: control, T1 (130 W m-2) and T2 (150 W m-2). The results showed that air temperature at 20 cm height, surface temperature and soil temperature in the 0–100 cm layers increased with warming. The biggest differences of T1 (1.66°C) and T2 (2.34 °C) appeared on the surface and at 20 cm depth, whereas the biggest amplitudes of T1 (27.15%) and T2 (35.81%) all occurred at 100 cm depth. Soil moisture showed different trends with warming in different soil layers. In the 0–40 cm layers, soil moisture decreased with warming. The biggest differences (–2.97% for T1 and –2.73% for T2) and amplitudes (–18.07% for T1 and –16.64% for T2) all appeared at 10 cm depth. In the 60–100 cm layers, soil moisture increased with warming. The biggest differences (2.53% for T1 and 6.45% for T2) and amplitudes (11.39% for T1 and 29.05% for T2) all occurred at 100 cm depth. Relative to control, vegetation height and aboveground biomass increased significantly in T1 and T2 (P <0.05), while vegetation coverage had not significant differences in T1 and T2 (P> 0.05). In T1 and T2, the amplitudes were 30.67% and 30.19% for vegetation height, and 36.22% and 27.87% for vegetation aboveground biomass, and 12.89% and 4.42% for vegetation coverage, respectively. In the path analysis between environment and vegetation properties, vegetation was directly affected by soil moisture at 40 cm and 60 cm depths, whereas indirectly influenced by relative humidity at 20 cm height and soil temperature at 40 cm depth. This might be related to the downward movement of the soil moisture caused by warming.
8
Content available remote On (m, n)-derivations of some algebras
EN
Let A be a unital algebra, δ be a linear mapping from A into itself and m, n be fixed integers. We call δ an (m, n)-derivable mapping at Z, if mδ(AB) + nδ(BA) = mδ(A)B + mAδ(B) + nδ(B)A + nBδ(A) for all A, B (…) A with AB = Z. In this paper, (m, n)-derivable mappings at 0 (resp. IA (…) 0, I) on generalized matrix algebras are characterized. We also study (m, n)-derivable mappings at 0 on CSL algebras. We reveal the relationship between this kind of mappings with Lie derivations, Jordan derivations and derivations.
EN
The Level-2 monthly GRACE gravity field models issued by Center for Space Research (CSR), GeoForschungs Zentrum (GFZ), and Jet Propulsion Laboratory (JPL) are treated as observations used to extract the equivalent water height (EWH) with the robust independent component analysis (RICA). The smoothing radii of 300, 400, and 500 km are tested, respectively, in the Gaussian smoothing kernel function to reduce the observation Gaussianity. Three independent components are obtained by RICA in the spatial domain; the first component matches the geophysical signal, and the other two match the north-south strip and the other noises. The first mode is used to estimate EWHs of CSR, JPL, and GFZ, and compared with the classical empirical decorrelation method (EDM). The EWH STDs for 12 months in 2010 extracted by RICA and EDM show the obvious fluctuation. The results indicate that the sharp EWH changes in some areas have an important global effect, like in Amazon, Mekong, and Zambezi basins.
10
Content available remote The error analysis of the three-pass differential interferometery
EN
The three pass differential interferometry technology is an important means of ground deformation monitoring, which has been successfully used in the large ground deformation monitoring and research such as the earthquake, volcano activity, glacial drift, landslides, and city settlement etc. However the technology is affected by multiple errors in practical application, which have serious influence on the deformation monitoring precision. For spaceborne radar, this paper derives the error propagation coefficients of the baseline error, the phase error, the atmospheric delay error and the earth curvature error and other types of errors on the three pass differential interferometry base on the [three pass differential interferometry] principle, and analyses the characteristics of these errors, finally discusses the influence rules of the errors on three pass differential interferometry.
PL
Artykuł dotyczy zagadnienia trójpasmowej interferometrii różnicowej, jako narzędzia do monitorowania deformacji gruntu w przypadku trzęsień ziemi, aktywności wulkanicznej itp. Na potrzeby radarów znajdujących się na orbicie kosmicznej, wyznaczono współczynnik propagacji błędów, typowych w tego rodzaju pomiarach (błąd fazowy, opóźnienie w atmosferze, zakrzywienie powierzchni Ziemi). Opisano mechanizm wpływu obecności tych błędów i uchybów na wynik działania metody.
EN
As the first radar altimetric satellite of China, HY-2 requires the precise orbit determination with a higher accuracy than that of other satellites. In order to achieve the designed radial orbit with the accuracy better than 10 cm for HY-2, the methods of precise orbit determination for HY-2 with the centimeter-level accuracy based on space geodetic techniques (DORIS, SLR, and satellite-borne GPS) are studied in this paper. Perturbations on HY-2 orbit are analyzed, in particular those due to the non-spherical gravitation of the earth, ocean tide, solid earth tide, solar and earth radiation, and atmospheric drag. Space geodetic data of HY-2 are simulated with the designed HY-2 orbit parameters based on the orbit dynamics theory to optimize the approaches and strategies of precise orbit determination of HY-2 with the dynamic and reduced-dynamic methods, respectively. Different methods based on different techniques are analyzed and compared. The experiment results show that the nonspherical perturbation modeled by GGM02C causes a maximum perturbation, and errors caused by the imperfect modeling of atmospheric drag have an increasing trend on T direction, but errors are relatively stable on the other two directions; besides, the methods with three space geodetic techniques achieve the radial orbit with the precision better than 10 cm.
12
Content available remote The solidification of CuCr alloys under various cooling rates
EN
The paper focuses on the solidification especially on the liquid phase separation of Cu-35 at. % Cr alloys under various cooling rates. When the solidification temperature is below the liquidus and above the spinodal temperature, solidification runs normally, with the growth of primary Cr-rich dendrites. When the solidification temperature is below the spinodal temperature, liquid phase separation should occur through the solidification process and the primary Cr-rich phase has a special nodular structure under an appropriate cooling rate. Large Cr-rich particles obtained from liquid phase separation can grow by absorbing smaller ones via the transfer of matter. Furthermore, some particles collide with each other, mutually losing surface energy by joining to form a single particle. The size of the Cr-rich particles obtained from liquid phase separation decreases with increasing cooling rate. Using thermodynamic calculations and referring to literature data, the viewpoints on liquid phase separation are systematized and applied to the CuCr system. Liquid phase separation in an undercooled liquid is not advantageous in refining the microstructure of alloys and should be restricted.
EN
This paper proposes a novel robust speech recognition approach based on the model-based feature compensation. The approach combines the GMM-based feature compensation and the HMM-based feature compensation together and employs the multiple recognition passes to achieve the best performance. In the initial recognition procedure, the GMM-based feature compensation approach is employed to give better clean model and noise model. Then we further refine these models by employing the HMM-based feature compensation approach. The statistical model of the clean speech and the noise is combined by using vector Taylor series (VTS) approximation. The experimental results show that the novel approach makes a significant improvement compared to the GMM-based feature compensation and the HMM-based feature compensation without any compensation in the initial pass.
14
Content available remote Weak solutions for a fourth order degenerate parabolic equation
EN
We consider an initial-boundary value problem for a fourth order degenerate parabolic equation. Under some assumptions on the initial value, we establish the existence of weak solutions by the discrete-time method. The asymptotic behavior and the finite speed of propagation of perturbations of solutions are also discussed.
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