Orbit determination of Chang’E-3 and positioning of the lander and the rover

Chang’E-3 landed on the east of Sinus Iridum area on December 14, 2013, performing China’s first successful soft landing on the lunar surface. We present the results on precision orbit determination and positioning of the lander and the rover. We describe the data, modeling, and methods used to achieve position knowledge over the period December 2–21, 2014. In addition to the radiometric X-band range and Doppler tracking data, delta differential one-way ranging data are also used in the calculation, which show that they strongly improve the accuracy of the orbit reconstruction. Total position overlap differences are about 20 and 30 m for the 100 km × 100 km and 100 km× 15 km lunar orbit, respectively, increased by ~50 % with respect to CE-2 and at the same level as other lunar spacecrafts of recent era such as SELENE and lunar reconnaissance orbiter (LRO). The position error of the soft landing trajectory is less than 100 m. A kinematic statistical method is applied to determine the position of the lander and relative position of the rover with respect to the lander. The position difference of the lander is better than 50 m compared to LRO photograph result. Compared with the delta very long baseline interferometry (VLBI) group delay between the lander and the rover, the delta VLBI phase delay can improve the relative position of the rover from ~1,000 to ~1 m.     

Orbit determination of Chang＇E-3 and positioning of the lander and the rover

Chang＇E-3 landed on the east of Sinus Iridum area on December 14, 2013, performing China＇s first successful soft landing on the lunar surface. We present the results on precision orbit determination and positioning of the lander and the rover. We and methods used to achieve period December 2-21, 2014. describe the data, modeling, position knowledge over the In addition to the radiometric X-band range and Doppler tracking data, delta differential one-way ranging data are also used in the calculation, which show that they strongly improve the accuracy of the orbit reconstruction. Total position overlap differences are about 20 and 30m for the 100km × 100km and 100 kmx 15 km lunar orbit, respectively, increased by ,- 50 % with respect to CE-2 and at the same level as other lunar spacecrafts of recent era such as SELENE and lunar reconnaissance orbiter （LRO）. The position error of the soft landing trajectory is less than 100 m. A kinematic statistical method is applied to determine the position of the lander and relative position of the rover with respect to the lander. The position difference of the lander is better than 50 m compared to LRO photograph result. Compared with the delta very long baseline interferometry （VLBI） group delay between the lander and the rover, the delta VLBI phase delay can improve the relative position of the rover from ～ 1,000 to ～1 m.     

Photometric modeling of the Moon using Lommel-Seeliger function and Chang’E-1 IIM data

The imaging intefferometer （IIM） aboard the Chang＇E-1 lunar orbiter is the first multispectral imaging spectrometer for Chinese lunar missions. Before science applications （e.g., FeO and TiO= mapping） of the IIM raw data, the radiance variation due to changes in illumination and viewing geometry has to be removed from the radiometrically calibrated IIM Level 2A images. To achieve this, we fit the IIM Level 2A radiance data with a Lornmel-Seeliger photometric model consisting of an exponential term and a fourth order polynomial in the phase function, without distinguishing between lunar maria and highlands. The exponential and the fourth order polynomial parameters are derived separately by fitting to two datasets divided at a solar phase angle threshold, avoiding a decrease in the phase function close to zero phase angle. Different phase angle thresholds result in coincident fitting curves between 20° and 75°, while large discrepancies occur at other phase angles. Then the derived photometric model is used to normalize the IIM Level 2A data to radiance values at an incidence and phase angle of 30° and emission angle of 0°. Our photometric model is validated by comparing two photometrically normalized IIM radiance spectra covering the same areas, showing a relative deviation consistent with the IIM preflight calibration.     

Application of EEG multipole model in the diagnosis of Alzheimer’s disease

In order to find the electroencephalogram (EEG) characteristic parameters typical of Alzheimer’s disease (AD) and explore an effective diagnostic method, a new mobile current multipole model was proposed to simulate the AD patient’s cortical dipole source activities. The indicators of goodness of fit (GOF) and DtononD (DD) were calculated from EEG samples to evaluate the performance of this model. Relevant results showed that this multipole model with higher GOF values and larger DD change well fitted the pathological electrical activities of cortical neurons aroused by AD’s extended sulcus and gyrus in the cerebral cortex. Meanwhile, the products of DD mean & standard variance were found in a clear linear correlation with the diagnostic data of mini-mental state examination (MMSE) used in AD clinics. Furthermore, by tracing this multipole model’s indicators in typical patients and contrasting with the functional magnetic resonance image (fMRI) as AD progressed, we suggested that the DD index may be suitable for monitoring the AD developments as a new diagnostic parameter.     

Application of EEG multipole model in the diagnosis of Alzheimer’s disease

In order to find the electroencephalogram (EEG) characteristic parameters typical of Alzheimer’s disease (AD) and explore an effective diagnostic method, a new mobile current multipole model was proposed to simulate the AD patient’s cortical dipole source activities. The indicators of goodness of fit (GOF) and DtononD (DD) were calculated from EEG samples to evaluate the performance of this model. Relevant results showed that this multipole model with higher GOF values and larger DD change well fitted the pathological electrical activities of cortical neurons aroused by AD’s extended sulcus and gyrus in the cerebral cortex. Meanwhile, the products of DD mean & standard variance were found in a clear linear correlation with the diagnostic data of mini-mental state examination (MMSE) used in AD clinics. Furthermore, by tracing this multipole model’s indicators in typical patients and contrasting with the functional magnetic resonance image (fMRI) as AD progressed, we suggested that the DD index may be suitable for monitoring the AD developments as a new diagnostic parameter.     

Preliminary results of TiO<Subscript>2</Subscript> mapping using Imaging Interferometer data from Chang’E-1

The distribution of titanium abundance on the lunar surface is important knowledge for lunar geologic studies and future resource utilization.In this paper,we develop a preliminary model based on"ground truths"from Apollo and Luna sample-return sites to produce a titanium abundance map from Chang’E-1 Imaging Interferometer(IIM) images.The derived TiO2 abundances are validated with Clementine UVVIS results in several regions,including lunar highlands neighboring the Apollo 16 landing site,and high-Ti and low-Ti maria near the standard site of Mare Serenitatis(MS2) .The validation results show that TiO2 abundances modeled with Chang’E-1 IIM data are overestimated for highlands(～0.7 wt.%) and low-Ti maria(～1.5 wt.%) and underestimated for high-Ti maria(～0.8 wt.%).     

Different types of La Niña events and different responses of the tropical atmosphere

Historical La Nia events since 1950 are divided into Eastern Pacific(EP) type and Central Pacific(CP) type,and the SSTA developing features as well as the different responses of the tropical atmosphere are further analyzed by using multiple datasets.Classification of different types La Nia is based on the normalized Ni o3 and Ni o4 indices and the SSTA distribution pattern during the mature phase.The minimum negative SSTA for CP La Nia is located over the equatorial central Pacific near the dateline,more westward than that of EP La Nia.It has stronger intensity and larger east-west zonal difference of SSTA over the equatorial Pacific than EP La Nia.Influenced by the different SSTA distribution pattern,CP La Nia induces more westward location of the anomalous sinking motion and the anomalous low-level divergent and high-level convergent winds over the equatorial eastern Pacific.The different response of the tropical atmospheric circulation between EP and CP La Nia is more significant in the upper troposphere than in the lower troposphere.However,the tropical precipitation patterns during the mature phase of EP and CP La Nia are much similar,except the less(more) precipitation over the equatorial central Pacific(eastern Indian Ocean-western Pacific) during CP La Nia than during EP La Nia.     

Comparative analysis of temperature and CO2 fluxes for winter wheat in Tibetan Plain and North China Plain using the EMD method

Comparative study of spectral properties of temperature and CO₂ fluxes measured by eddy covariance method at Yucheng (36°57′N, 116°36′E, 28 m a.s.l., in the North China Plain) and at Lhasa (29°41′N, 91°20′E, 3688 m a.s.l., on the Tibetan Plateau) is described using the empirical mode decomposition (EMD) method. The main results are: (1) The intrinsic oscillation modes or intrinsic mode functions (IMFs) were extracted from data of temperature (T) and CO₂ fluxes (F) measured at Yucheng (T₁ and F₁) and Lhasa (T₂ and F₂). (2) Hilbert transform was applied to these IMF components, then the Hilbert-Huang spectra and the marginal spectra of these data were obtained. (3) Comparison of temperature and CO₂ fluxes in North China Plain and on Tibetan Plain illustrated that the characteristic frequencies corresponding to T₁, F₁, T₂ and F₂ are 0.05 Hz, 0.03 Hz, 0.014 Hz and 0.005 Hz, respectively.     

基于等高线的数字高程模型带状区域建模法

为简化传统方法用等高线地形图建立数字高程模型(DEM)时需先提取离散点数据、构建大量不规则三角形网(TIN)的繁琐过程,提出简便的带状区域法.首先对等高线进行完整性处理并按多边形编号存储,利用既有的等高线及其单边邻接关系将整个地形图划分为相互独立的带状区域,形成DEM模型;通过搜索查询点所在的带状区域及对应的等高线高程值,采用距离加权平均法计算查询点的高程.该方法建立的DEM模型明显减少了网格数量和存储空间,高程插值计算精度不低于TIN法,建模效率提高,适合于建立基于等高线的大型DEM.     

Effect of MTECl on the functional expression of TCRαβ~ + 3G11~- 6C10~-CD4~+CD8~- thymocyte subset

A murine CD4+ thymocyte subset with phenotype of TCRαβ + 3G11- 6C10- CD4 + CD8- CD69 +/- HSAmed/locontains the cells in relatively functional matured status. The functional property of the cells in this subset is characterized by the unique pattern of cytokine production at transitional stage from Th0 to Th2 type with the latter being the dominant type. After being co-cultured with murine thymic medullary epithelial cell line (MTEC1) cells, a murine thymic medullary type epithelial cell line, the TCRαβ(T 3G11 6C10-CD4 + CD8- CD69+/- HSAmed/l? thy-mocytes, has exhibited significantly higher levels of proliferation capability and IL-6 production, whereas the production of IL-4 and IL-10 is suppressed after co-culturing with MTECl. By contrast, MTECl could not induce thymocytes to secrete Th1 type of cytokines. The results suggest that MTECl can regulate functional status of this thymocyte subset and induce them to develop into a specialized Th2 subset.     

Fabrication of Fe–TiC–Al2O3 composites on the surface of steel using a TiO2–Al–C–Fe combustion reaction induced by gas tungsten arc cladding

The aim of the present study was to fabricate Fe–TiC–Al₂O₃ composites on the surface of medium carbon steel. For this purpose, TiO₂–3C and 3TiO₂–4Al–3C–xFe (0 ≤ x ≤ 4.6 by mole) mixtures were pre-placed on the surface of a medium carbon steel plate. The mixtures and substrate were then melted using a gas tungsten arc cladding process. The results show that the martensite forms in the layer produced by the TiO₂–3C mixture. However, ferrite–Fe₃C–TiC phases are the main phases in the microstructure of the clad layer produced by the 3TiO₂–4Al–3C mixture. The addition of Fe to the TiO₂–4Al–3C reactants with the content from 0 to 20wt% increases the volume fraction of particles, and a composite containing approximately 9vol% TiC and Al₂O₃ particles forms. This composite substantially improves the substrate hardness. The mechanism by which Fe particles enhance the TiC + Al₂O₃ volume fraction in the composite is determined.