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Dynamic Analysis of Touchdown Impact for the Landing Gear of Reusable Launch Vehicle and Experimental Evidence
YUAN Han, WANG Xiaojun, ZHANG Hongjian, MOU Yu, WANG Lei, WANG Chen
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (6): 977-988.   DOI: 10.13209/j.0479-8023.2022.084
Abstract722)   HTML    PDF(pc) (3747KB)(294)       Save
In order to describe the lateral vibration of the landing gear caused by landing of launch vehicle, an equivalent model for the excitation of landing impact is proposed. In this model, the excitation is equivalent to the superposition of impact excitation and steady excitation. Secondly, the bending vibration modes of the landing gear are established by the assumed mode method, where the coupling term of the longitudinal deformation caused by transverse deformation is included in the expression of bending vibration. The dynamic response, excited by the landing impact, is solved by the mode superposition method, so as to obtain a semi-analytical solution for the problem. The real product experiments of vertical landing impact show that the proposed model is able to accurately describe the lateral vibration and maximum moment of the landing gear. Finally, we analyze how the parameters of the configuration and strength of materials affect the landing gear using the proposed model. The result can guide the parameter design of the landing gear in the engineering implementation.
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Analysis of Bi-directional Reranking Model for Uyghur-Chinese Neural Machine Translation
ZHANG Xinlu, LI Xiao, YANG Yating, WANG Lei, DONG Rui
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (1): 31-38.   DOI: 10.13209/j.0479-8023.2019.093
Abstract1287)   HTML    PDF(pc) (899KB)(186)       Save
The fitting training of neural machine translation is easy to fall into a local optimal solution on a lowresource corpus such as Uyghur to Chinese, resulting in the translation result of a single model may not be a global optimal solution. In order to solve this problem, the probability distribution predicted by multiple models is effectively integrated through the ensemble strategy, and multiple translation models are taken as a whole. At the same time, the translation models with opposite decoding directions are integrated by the reordering method based on cross entropy, and the candidate translation with the highest comprehensive score is selected as the output. The experiment on CWMT2015 Uighur-Chinese parallel corpus shows that proposed method has 4.82 BLEU values improvement compared with a single transformer model.
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Identity-Based Motivation Theory and Its Implication to Academic Outcome of College Students
WANG Chunhua, WANG Lei
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (6): 1170-1178.   DOI: 10.13209/j.0479-8023.2019.090
Abstract1282)   HTML    PDF(pc) (457KB)(166)       Save
This paper introduces the theory of identity-based motivation which is a suited approach and social psychological theory about human’s motivation and goal-pursuit. In the perspective of this model, people act in a way that congruent with the identity primed by current context. Doing something or not was influenced by the perception of identity which comes to the mind. Related research involving in the area of health behavior and academic outcome was reviewed. It suggested that future research might consider whether some special identity types in certain culture context and undesirable identity might influence academic outcome among college students, as well as the moderate and mediate role of cognitive ability and personality factors.
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3-D Seismology Interpretation and Structure Analysis of Early Permian Flood Basalt Volcanic Edifices in Tarim Basin
GAO Zhongbo, WANG Lei, TIAN Wei, GONG Mingyue
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (3): 555-562.   DOI: 10.13209/j.0479-8023.2017.118
Abstract967)   HTML8)    PDF(pc) (17907KB)(177)       Save

The volcano edifices from Tazhong-47 exploring area in the middle of Tarim basin are interpreted by 3-D seismological reflection data coupled with physical drilling well logs. Based on seismic profile interpretation and velocity analysis, the structure of the volcano edifices of continental flood basalt (CFB) are studied. The result shows that reflectors beneath the Tazhong-47 volcanic edifice are corresponding to basaltic intrusions, which have average velocity of 5800 m/s, and the clastic wall rocks have average velocity of 3500 m/s. Based on the calculation of the stratigraphical thickness between the two horizontal markers (Permian-Triassic boundary as named “P-top” and top of bioclastic limestone as named “BL-top”) at drilling well, it is found that the basaltic intrusions make the upper layer relative to the lower layer marks move the 159.1 m upward. This is equal to the uplift extent. By using the “velocity pull-up (VPU)” effect, the total thickness of the basaltic sills is calculated to be 167.7 m, which is similar to the uplift extent. This similarity suggests that the uplift at the volcanic center was the result of “forced folding” caused by the intrusion of the magma. This emplacement style is the same as that of the Karoo large igneous province and the North Atlantic igneous province.

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Scattered Sand Rock Mechanics Field Modeling Based on Seismic Pre-stack Inversion
FANG Yuanyuan, SHI Yongmin, WANG Lei, DU Shuheng, SHENG Yingshuai
Acta Scientiarum Naturalium Universitatis Pekinensis    2015, 51 (6): 1040-1046.   DOI: 10.13209/j.0479-8023.2015.075
Abstract1042)      PDF(pc) (1445KB)(964)       Save

For the sake of solving the problem in Daqing Fuyang low permeability reservoirs which is scattered distribution, and changes so rapidly in the mechanical properties of rock that restricts the reservoir reconstruction, a new method was presented in this paper. On the basis of lots of rock mass mechanics model of in situ experiments, the relationship between P-wave and S-wave velocities was studied, and P-wave and S-wave velocity bodies from pre-stack elastic parameter inversion were obtained. Besides, the rock mass mechanics parameters according to rock physics equation were gotten and the multiple regression analysis method was used to get well point elastic parameter values. The well points and cross-hole elastic parameter values were combined, and geostatistics method was utilized to establish the heterogeneity of rock mass mechanics field. The geological basis was provided to optimize hydraulic fracturing parameter design to increase production.

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The Effect of Observing Others’ Lives on the Perceived Tolerance of Pain
WEI Wenqi;WANG Lei;QIAO Lingsi;LI Chen
Acta Scientiarum Naturalium Universitatis Pekinensis    2015, 51 (5): 976-982.   DOI: 10.13209/j.0479-8023.2015.094
Abstract1143)      PDF(pc) (388KB)(282)       Save
Based on social learning and social comparison theories, the authors investigated whether the exposure to the successful or miserable lives of others could influence participants’ pain tolerance. Results consistently showed that people who were exposed to the successful or miserable lives of others reported higher tolerance of pain than people who were exposed to the ordinary lives of others. This result was present across different samples (employee sample in Experiment 1, and university student samples in Experiment 2), different priming methods (story of a waiter’s experience in Experiment 1, and a student’s life in Experiment 2). All these findings suggest that people can adaptively select different paths to regulate themselves in order to cope with pain.
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Study on Flow Unit of Tight Sandstone Reservoir: A Case of Yanchang Formation Chang-61 Resrvoir in Erdos Basin
XIONG Wentao,SHI Yongmin,LIU Xinju,WANG Xiaojun,WU Luofei,WANG Lei,GUO Xinwei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract699)      PDF(pc) (744KB)(446)       Save
The authors proposed on approach of multiple channel superimposed tight sandstone reservoir flow unit by using the data from a block in the middle-east part of Erdos Basin. The parameters such as porosity, permeability, reservoir quality coefficient and flow zone index were selected to classify the flow units. With the cluster analysis and discriminant analysis method, tight sandstone reservoir flow units were classified and evaluated. The study shows that proposed method is reasonable and feasible, and has certain guiding significance for development of similar reservoirs.
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Volcanic Debris Flow: A New Type of Lower Cretaceous Reservoir in Hailar-Tamtsag Basin
LI Xiaomin,SHI Yongmin,JIANG Hongfu,WANG Lei,QIN Xiaoshuang,WU Wenjuan,CHAI Zhi
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract593)      PDF(pc) (7884KB)(366)       Save
The lower cretaceous oil-bearing reservoir of Hailar-Tamtsag basin is composed of several NNE trending volcanic rift basin group during the early cretaceous. In the early phase, large-scale volcanic debris flow sediment filled in the lacustrine basin center where the source was prolific, which then caused the formation of endogenous volcanic debris flow oil and gas reservoirs that became a new and major reservoir type in the basin. The petrology experiments suggest that the combination of lithology in this reservoir is different from the usual pyroclastic rock such as “tuffaceous sandstone” and “tuff glutenite”. Its mixed facies are caused by rapid accumulation of volcanic debris flow with specific sedimentary origin and paleogeographic environment, which is also a new type of reservoir sedimentary origin on which there is less domestic and international research. The characteristics of this reservoir includes mélange accumulation of tuff and normal glutenite, complex types of pore space, strong water-sensitivity, low permeability, fast change of facies, strong heterogeneity. Since the reservoir is a special type of reservoir with unstable physics and chemistry, it has strong sensibilities and weak cementation, which likely causes strong water-sensitivity, speed-sensitivity, casing damages and deformations, sand productions, and the development is difficult. The investigation of the genetic mechanism of volcanic debris flow reservoir will provide the theoretical basis for optimizing the development method, making rational policy and exploiting economically and effectively.
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Theory and Application of Numerical Simulation of Asymmetric Hydraulic Fractures in Ultra-Low Permeability Reservoirs
WU Wenjuan,SHI Yongmin,WANG Xiaojun,LIU Hongtao,QIN Xiaoshuang,WANG Lei,CHAI Zhi,LI Xiaomin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract662)      PDF(pc) (1679KB)(324)       Save
Based on Chang-6 formation of Yanchang group in Erdos basin, built the geology, 3D rock mechanics and 3D stress field models with core and logging data, and obtained the properties of any point between wellbores. With the fracturing principle, the actual geometry of the fractures can be calculated, and the asymmetry fractures model can be built, including the length, height, width and the direction of the fractures. With the analysis of production history, the residual oil distribution can be obtained, and the multiple fracturing procedure can be designed. With the guidance of the asymmetric fracture models, the daily increase of production is more than 4 ton.
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Pore-Throat Structure Evaluation of Artificial Cores with Rate-Controlled Porosimetry
CHAI Zhi,SHI Yongmin,XU Changsheng,ZHANG Yuguang,LI Hong,WU Wenjuan,XU Hongbo,WANG Lei
Acta Scientiarum Naturalium Universitatis Pekinensis   
An ANN-CA Modeling Method for Land Cover Change in the Karst Area of China: A Case Study of Maotiao River Basin
WANG Lei,WANG Yang,CAI Yunlong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract659)      PDF(pc) (2194KB)(589)       Save
The land use of Karst areas in Southwest China changed drastically due to its fragile eco-environment properties and the disturbance from human activities. Modeling and analyzing these changes is impeded by its complex surface features and the intensive human-environment interaction. In order to solve this problem, a combined ANN-CA modeling method is used on Maotiao River Basin in Guizhou Province by the modeling results compared with the actual land use map. The results show 87.62% accuracy with confusion matrix, 57.36% with figure of merit, and all of the selected landscape indexes are similar between them, proving this method a good option for the land use change analysis in Karst and other similar areas.
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Analysis of Predominant Factors of Volcanic Reservoirs in Carboniferous of Junggar Basin
QIN Xiaoshuang,SHI Yongmin,WU Wenjuan,KOU Yu,WANG Lei,LI Xiaomin,CHAI Zhi
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract701)      PDF(pc) (6688KB)(351)       Save
According to the core observation and statistics of physical properties, it is found that weathering, tectonism, lithology and litho-facies are the predominant factors of volcanic reservoirs in Carboniferous of Junggar Basin. The reservoir space includes primary fractures, primary porosity, secondary porosity and secondary fractures. The permeability is mostly controlled by fractures. Weathering crust is the main reservoir of volcanic rock in Carboniferous. High quality reservoirs are mainly located 250 m from the top of weathering crust. Among all the high quality reservoirs, the paleohigh around the depression is the better position. As the distance from the top of weathering crust increases, the filling degree of fractures as well as porosity becomes higher and this degrades the reservoir quality.
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Pressure Sensitivity and Its Genetic Mechanism of Igneous Rock Formations in Changshen Gas Field
WANG Lei,SHI Yongmin,SONG Qiuguo,CHAI Zhi,QIN Xiaoshuang,LI Xiaomin,WU Wenjuan
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract548)      PDF(pc) (1330KB)(397)       Save
The core samples of igneous rock formations with low permeability and low porosity in Jilin Changshen well block are tested for their pressure sensitivity. The result shows that permeability recovery rate of these samples is not more than 11%, which indicates high pressure sensitivity of the formations. By observing core samples and comparing the result of pressure sensitivity tests with those from igneous rock core samples of other regions, it shows that the pressure sensitivity of igneous rock formations is relevant to lithology, structure, construction, development and type of porosity and fracture. Different from the unitary diagenesis of sandstone, the complex diagenesis of igneous rock leads to different pressure sensitivity in different areas. Therefore the pressure sensitivity of different igneous rock formations should be treated differently. Meanwhile, pressure sensitivity of a certain well may not be the same in different igneous layers.
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Retrieval of Aerosol Optical Depth from Fengyun-2C Geostationary Satellite Observation: Theory and Implementation
REN Tong,GAO Ling,LI Chengcai,MAO Jietai,LI Wanbiao,SHI Guangming,YANG Dongwei,WANG Lei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract743)            Save
How to use the measurement from the visible channel of Chinese Fengyun-2C geostationary satellite to retrieve aerosol optical depth (AOD) is discussed. By calculating mean surface reflectance at the same local time of each day in one month, the randomicity of the estimated surface reflectance can be reduced. The influence of different values of AOD assumed in the cleanest days on the quality of final AOD product is analyzed. In addition, the data in May 2008 was used to test the proposed algorithm and the results were compared with the AOD product from six AERONET sites in East Asian and MODIS AOD product respectively. Last, the error sources were analyzed in the retrieval of AOD from FY2C satellite, and the corresponding possible schemes to decrease the error influence and improve the quality of FY2C AOD product were investigated. The comparison indicates that in East Asian the AOD product can display the pattern of aerosol distribution, but overestimates the values of AOD in southwest of China and low latitude areas, and underestimates the values of AOD in east of China.
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Assessment of Environmental Benefits from Phasing out CFCs in Refrigerator Industry of China
WAN Tingting,WAN Dan,WANG Lei,DOU Yanwe,SUN Xuezhi,HU Jianxin
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract525)            Save
The environmental benefits for phasing out CFCs in China’s refrigerator sector, such as the reduction of emissions of greenhouse gases, ozone-depleting substances and the electricity consumption, were analyzed by comparing the scenario of phasing out CFCs to the non-Montreal Protocol baseline scenario, respectively. It was found that 273.5 million tons CO2-eq and 4.7×104 tons ODP had been reduced by the end of 2008. After 2008, 619.8 million tons CO2-eq and 1.0×105 tons ODP will be reduced. Phasing out CFCs in China’s refrigerator industry made a considerable contribution to relieve global warming and reduce ozone depletion substances. By using substitute refrigerants, 2.8×1010 kWh of electricity was saved, which was equivalent to 24.2 million tons CO2 and of great practical significance in China’s resource conservation, energy-saving and emission-reduction.
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Validation of the Emotional Intelligence Scale
HUANG Yunhui,Lv Aiqin,WANG Lei,SHI Junqi
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract982)            Save
The Chinese version of the Emotional Intelligence Scale was revised. The questionnaire was administrated to two samples with a total of 920 undergraduates. Item analysis show that all of the 33 items meet psychometric criteria. The exploratory and confirmatory factor analysis indicates that the Chinese version of Emotional Intelligence Scale is composed of four dimensions(CMIN/DF=2.19,CFI=0.90,GFI=0.93,AGFI=0.90,RMSEA=0.05).It is different from the one-factor structure and the four factor structure, which are reported in previous studies using samples in the West. The internal consistency reliability of the scale was 0.85. Further analysis reveals that there are no gender differences. The convergent validity and criterion-related validity are satisfactory. The revised Chinese version of the Emotional Intelligence Scale has good psychometric quality and can be applied in related psychological research areas.
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The Revision of the Personal Need for Structure Scale in Chinese
CHEN Yang,HUANG Yunhui,WANG Lei,SHI Junqi
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract784)            Save
The purpose was to revise the Chinese version of the Personal Need for Structure (PNS) Scale. The questionnaire was administered to 1042 participants. The item analysis showed that all of the 11 items met the psychometric criteria. The confirmatory factor analysis indicated that the Chinese version of PNS containing 11 items was composed of two dimensions, which remained the same structure as the original version. These two dimensions were desire for structure and response to lack of structure. The internal consistency reliability and the split-half reliability were all above 0.80. The test-retest reliability was 0.79. The results indicated that the scale has acceptable discriminant validity and convergent validity.
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Multimode and Its Application in Climate Analysis
WANG Lei,KANG Dujuan,LI Xiaodong
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract643)            Save
The probability distributions of climatic elements are discussed. Based on the characters of them, a multimode model is introduced and verified through the nonlinear fitting. The climate features of quasi-biennial oscillation of the stratospheric zonal wind over equator, the ENSO Index, the surface pressure at Reykjavik(21.90°W 64.13°N)and Swedish temperature, and the Northern Hemisphere tree ring all show that the multimode are universal in the climatic system.
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The Structure and Measurement of Self-efficacy
WANG Lei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1145)            Save
The goal of this study is to establish a test to measure Self-efficacy. One hundred and forty-nine college students participated in the study. Subjects were asked to rate if each item of an author-designed Self-efficacy Inventory (SEI) could be used to describe themselves on a 6-point scale with "1" representing "extremely not appropriate" and "6" representing "extremely appropriate". Rotter Internal-external Control Scale, Self-discrepancy, Chinese SCL90 Depression Sub-scale, and Sherer's Self-efficacy Scale were tested as well. The same subjects were tested with SEI again two weeks later. The results shown that 19 items were chosen to compose the final SEI test, of which the mean score of the sample was 63.09 while standard deviation was 12.645. There was no significant sex difference (t=0.14, P=0.88). Factor Analysis revealed one factor which explained 32.4% of the total variance. The test met the basic reliability requirements with Cronbach a=0.878 and r=0.817 for test-retest reliability, and was significantly and negatively correlated with Rotter Internal-external Control Scale (r=-0.511, P<0.001), actual-ideal self-discrepancy (r=-0.420, P<0.001), actual-ought self-discrepancy (r=-0.450, P<0.001), and depression (r=-0.398, P<0.001). This test was also significantly correlated to Sherer's Self-efficacy Scale with r=0.6140 (P<0.0001) to its general efficacy and r=0.5379 (P<0.0001) to its social efficacy.
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