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A Transformer-based Syntax Tree Decoder for Handwritten Mathematical Expression Recognition
ZHOU Bohan, CAO Jian, WANG Yuan
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (6): 909-914.   DOI: 10.13209/j.0479-8023.2023.085
Abstract301)   HTML    PDF(pc) (551KB)(187)       Save
Most of the existing tree-structured decoding methods of handwritten mathematical expression recognition are based on the recurrent neural networks, which have low training efficiency and complicated training process. In order to prove this problem, the authors propose a handwritten mathematical expression recognition model based on Transformer structure, which can decode the syntax tree of expressions directly. Experimental results show that the proposed tree-structured decoding method achieves better performance than the string decoding methods base on Transformer on several datasets of handwritten formula recognition tasks, and show the potential to surpass recurrent neural network tree decoding methods.
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AdaPruner: Adaptive Channel Pruning and Effective Weights Inheritance
LIU Xiangcheng, CAO Jian, YAO Hongyi, XU Pengtao, ZHANG Yuan, WANG Yuan
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (5): 764-772.   DOI: 10.13209/j.0479-8023.2022.115
Abstract293)   HTML    PDF(pc) (772KB)(213)       Save
Previous channel pruning methods require complex search and fine-tuning processes and are prone to fall into local optimal solutions. To solve this problem, the authors propose a novel channel pruning framework AdaPruner, which can generate corresponding sub-networks adaptively for various budget complexities and efficiently select the initialization weights suitable for the current structure by sparse training once. Experimental results show that the proposed method achieves better performance than previous pruning methods on both commonly used residual networks and lightweight networks on multiple datasets for image classification task. 
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Reinforcement Learning of Spiking Neural Network Based on Knowledge Distillation
ZHANG Ling, CAO Jian, ZHANG Yuan, FENG Shuo, WANG Yuan
Acta Scientiarum Naturalium Universitatis Pekinensis    2023, 59 (5): 757-763.   DOI: 10.13209/j.0479-8023.2023.065
Abstract266)   HTML    PDF(pc) (1417KB)(188)       Save
We propose the reinforcement learning method of Spike Distillation Network (SDN), which uses STBP gradient descent method to realize the knowledge distillation from Deep Neural Network (DNN) to Spiking Neural Network (SNN) reinforcement learning tasks. Experiment results show that SDN converges faster than traditional SNN reinforcement learning and DNN reinforcement learning methods, and can obtain a SNN reinforcement learning model with smaller parameters than DNN. SDN is deployed to the neuromorphology chip, and the power consumption is lower than DNN, proving that SDN is a new and high-performance SNN reinforcement learning method and can accelerate the convergence of SNN reinforcement learning.
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Design and Implementation of Object Detection Acceleration Module Based on an ARM+FPGA Heterogeneous Platform
LI Fang, CAO Jian, LI Pu, XIE Hao, ZHAO Xiongbo, WANG Yuan, ZHANG Xing
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (6): 1035-1041.   DOI: 10.13209/j.0479-8023.2022.089
Abstract546)   HTML    PDF(pc) (814KB)(234)       Save
Object detection algorithms based on deep learning use big models are difficult to be deployed at the edge. Taking YOLO (you only look once) object detection algorithm as an example, an acceleration module based on an ARM+FPGA heterogeneous platform is proposed. The FPGA chip accelerates the forward process of the compressed model while ARM is responsible for process scheduling. Experiment results show that the peak performance of the system reaches 425.8 GOP/s under 200 MHz working frequency. The system on a Xilinx ZCU102 board achieves a frame rate at 30.3 fps, while the power consumption is 3.56 W. It is also configurable.
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An iRAM-based Light-Weight Cryptographic Algorithm Implementation Scheme against Physical Memory Disclosure Attacks
LI Yanchu, JING Jiwu, LEI Lingguang, WANG Yuewu, WANG Pingjian
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (6): 1023-1034.   DOI: 10.13209/j.0479-8023.2022.095
Abstract306)   HTML    PDF(pc) (729KB)(146)       Save
An iRAM-based light-weight secure cryptographic algorithm implementation scheme is proposed, which can execute multiple cryptographic algorithms concurrently without affecting the iRAM-assisted functions of the system. The scheme restricts the sensitive data in the cryptographic algorithm implementation to a single loadable segment, separates the non-sensitive data from this segment, and modifies the loading procedure of the trusted applications to allocate only the segment containing sensitive data to the iRAM space. It can minimize the occupation of iRAM by cryptographic operations. A series of representative cryptographic algorithms are implemented on the real device. The experimental results show that the performance overhead of all cryptographic algorithms is less than 4.3%, and each algorithm’s demand for iRAM is less than 4.5 KB, saving more than 78% compared with existing schemes, which supports the deployment of the scheme on all mainstream platforms.
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Research on Differences of Image Perception of Beijing Historical and Cultural Districts among Various Cultural Groups
PENG Xia, WANG Yun, HUANG Zhou
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 949-958.   DOI: 10.13209/j.0479-8023.2022.078
Abstract429)   HTML    PDF(pc) (4217KB)(154)       Save
Based on the tourist online comment data of Beijing’s historical and cultural districts released by TripAdvisor from 2010 to 2019, and on the basis of constructing the place attachment model of inbound tourists, the authors use content analysis to discuss the discrepancies of various cultural groups’ perception image on historical and cultural districts in Beijing. This paper concludes that diverse culture groups have differences in cognitive, affective and overall image on historical and cultural districts; the authenticity of the district environment, public facilities and the perception of crowding affect the place attachment of different cultural groups, and then affect the cultural groups’ image perception of historical and cultural districts; cultural heterogeneity leads to great differences in place attachment of different cultural groups to the same historical and cultural district.
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Comprehensive Performance Evaluation Framework of Water Landscape with the Orientation of Water Eco-system Service
LIU Jiaju, WANG Zhiyong, WANG Chunlian, WU Shanshan, WANG Yuhong, YANG Pingjian
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 909-915.   DOI: 10.13209/j.0479-8023.2022.049
Abstract395)   HTML    PDF(pc) (517KB)(167)       Save
The existing landscape performance evaluation research has problems such as the lack of ecological theory support in the evaluation system, the lack of comprehensive performance evaluation of water landscape according to the scale of site design, the completeness of the selection of framework or indicators, and the lack of typicality and availability. Therefore, the authors fully combed the four existing systems of landscape performance evaluation. At the same time, the related theories of water ecosystem services were studied, the types and elements of water ecosystem services were identified, and then the logical relationship between water ecosystem services and landscape performance evaluation were clarified. Based on the water ecosystem service theory, combined with the relevant international landscape performance evaluation system and indicators, the authors built a scientific and operable comprehensive performance evaluation index system for water landscapes, including 5 types of project layers, 10 types of criteria layers and 28 indicators. The relevant results are expected to provide a basis for the 
optimization of design strategies for water landscape designers. 
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Post Training Quantization Preprocessing Method of Convolutional Neural Network via Outlier Removal
XU Pengtao, CAO Jian, CHEN Weiqian, LIU Shengrong, WANG Yuan, ZHANG Xing
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 808-812.   DOI: 10.13209/j.0479-8023.2022.082
Abstract404)   HTML    PDF(pc) (452KB)(251)       Save
In order to improve the performance of post training quantization model, a quantization preprocessing method based on outlier removal is proposed. This method is simple and easy to use. The outliers of weight and activation value are removed only through simple operations such as sorting and comparison, so that the quantization model loses only a small amount of information and improves the accuracy. The experimental results show that the performance can be significantly improved by preprocessing with this method before using different quantization methods.
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Layer Pruning via Fusible Residual Convolutional Block for Deep Neural Networks
XU Pengtao, CAO Jian, SUN Wenyu, LI Pu, WANG Yuan, ZHANG Xing
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (5): 801-807.   DOI: 10.13209/j.0479-8023.2022.081
Abstract508)   HTML    PDF(pc) (846KB)(204)       Save
Aiming at the problems of long inference time and poor effect of the compression model obtained by the current mainstream pruning methods, an easy-to-use and excellent layer pruning method is proposed. The original convolution layers in the model are transformed into fusible residual convolutional blocks, and then layer pruning is realized by sparse training, therefore a layer pruning method with engineering ease is obtained, which has the advantages of short inference time and good pruning effect. The experimental results show that the proposed layer pruning method can achieve a very high compression rate with less accuracy loss in image classification tasks and object detection tasks, and the compression performance is better than the advanced convolutional kernel pruning methods.
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A Charge Recycling Scheme with Read and Write Assist for Low Power SRAM Design
ZHANG Hanzun, JIA Song, YANG Jiancheng, WANG Yuan
Acta Scientiarum Naturalium Universitatis Pekinensis    2021, 57 (5): 815-822.   DOI: 10.13209/j.0479-8023.2021.039
Abstract732)   HTML    PDF(pc) (1170KB)(222)       Save
In order to cut down the dynamic power of static random access memory (SRAM), a bitline charge cycling based read and write assist circuit for SRAM is presented. Compared with the traditional design, the assist circuit saves and reuses the bitline charge which should be directly discharged during read and write operation to reduce bitlines charging power consumption in the next cycle. The SRAM memory is built by the SMIC 14 nm FinFET spice model, and the power supply voltage is 0.8 V. The simulation results show that the power consumption of the proposed SRAM array is reduced by 23%–43% compared with the traditional design, and the SNM and WNM has increased by at least 25% and 647.9% respectively.
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Estimation of Agricultural Non-point Source Pollution Loads Based on Improved Export Coefficient Model
HU Qing, GUO Huaicheng, WANG Yuqi, ZHANG Yang, LI Zheng, FU Zhenghui, LU Wentao
Acta Scientiarum Naturalium Universitatis Pekinensis    2021, 57 (4): 739-748.   DOI: 10.13209/j.0479-8023.2021.049
Abstract662)   HTML    PDF(pc) (1455KB)(93)       Save
The Dianchi watershed Basin was selected as a typical watershed. Considering the differences of regional natural geography, hydrometeorology and human activities, using 1 km×1 km grid data, the detailed simulation calculation of the pollutants entering the water source of agricultural sources is carried out. The rainfall driving factors, terrain driving factors, surface runoff factor, underground storage/groundwater runoff factor and interception factor are obtained. The average comprehensive water inflow coefficients of TN and TP from agricultural sources in Dianchi Basin in 2016 are 0.447 and 0.342 respectively, and the actual water inflow loads of TN and TP from agricultural sources in 2016 are 577.39 t and 167.62 t respectively. The results show that the discharge of agricultural source pollutants and the load of influent water have significant spatial variation in Dianchi Lake Basin. 81.0% of nitrogen and 74.2% of phosphorus were concentrated in Caohai land area and the north coast of the open sea. The largest emission was in the upper reaches of Panlong River, with nitrogen and phosphorus accounting for 21.9% and 20.2% respectively. It is also found that livestock and poultry breeding account for more than 90% of the total TN and TP emissions of from agricultural sources, which should be the focus of agricultural source pollution control. 
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Changes of Surface and Groundwater Reserves in the Narenguole River Basin
WANG Yue, WANG Yichu, NI Jinren
Acta Scientiarum Naturalium Universitatis Pekinensis    2021, 57 (2): 371-380.   DOI: 10.13209/j.0479-8023.2021.016
Abstract955)   HTML    PDF(pc) (5539KB)(170)       Save
Based on the data from 2001–2016, we investigated the variation trends in surface water and groundwater reserves of the Narenguole River, their response relationship and influencing factors. The trend distribution of groundwater reserves is uneven and the seasonal variation is obvious. The co-varying change of surface water and groundwater reserves presents a “stable-decrease” trend in the northern part of the basin. In the part of the Tulagt Ar Gol River, the surface water decreases but the groundwater increases, while the “stableincrease” and the “decrease-decrease” co-varying trends are observed respectively in the West and East Taijinar Lakes of the rump area. The main factors influencing the change of water reserve include temperature, soil section thickness, irrigation factors and population factors. Based on the response characteristics of surface water and groundwater changes in different areas of the basin, we get insights into the typical non-consistent response relationship between them, which is very helpful to realize the integrated management of surface water and groundwater and the protection of ecological environment in the basin.
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Water Budget Characteristics of Over-Irrigated Oasis in Arid Region of Northwest China
WANG Bei, YAN Chunhua, WANG Yue, LI Cheng, ZHANG Qingtao, QIU Guoyu
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (6): 1122-1128.   DOI: 10.13209/j.0479-8023.2020.103
Abstract831)   HTML    PDF(pc) (6551KB)(188)       Save
Based on the water balance equation, a field experiment was carried out to observe the dynamic characteristic of volumetric soil water content during growing season of 2012 and to explore the impact of irrigation on the oasis water budget. The results showed that in the Zhangye oasis, the volumetric soil water content at the depth of 40–60 cm was higher than that at the depth of 0–20 cm during days without precipitation and irrigation. Heavy precipitation has an obvious impact on the volumetric soil water content at the depth of 0–20 cm while irrigation has an obvious impact at the depth of 0–100 cm. The daily evapotranspiration (ET) was 2.83 mm/d during days without precipitation and irrigation. The ET volume of the third day after precipitation increased by 16% compared to the ET volume before precipitation. The ET rate of the second day after irrigation was observed with an increase of 88% compared to the ET rate before irrigation, indicating that the impact of irrigation on ET was more significant than that of precipitation. The primary incomings of the water budget in the oasis was irrigation, which accounted for 89.7% of the total incomings. The main outgoings of the water budget in the oasis was deep percolation (DP), which accounted for 81% of the total outgoings. The irrigation water requirement was only 213 mm during the growing season of 2012, but the real irrigation volume exceeded the irrigation water requirement by 474 mm. Excessive deep percolation and serious water wastage was obvious during growing season due to the heavy irrigation.
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Preparation and Pyrolysis Kinetics of Phenolic Resins of Main Phenols in Semi-coking Wastewater
WANG Yali, WANG Yufei, LI Jian, PENG Jiajia, CAO Shuai, YAN Long
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (6): 975-982.   DOI: 10.13209/j.0479-8023.2020.030
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The composition and concentration of organic compounds in semi-coking wastewater were determined by GC-MS. The mixtures of a few of the five most representative phenolic substances (phenol, m-cresol, 2,3-dimethylphenol, catechol and 2,6-dimethylphenol) were utilized to simulate semi-coking wastewater. Phenolic resins in the simulated semi-coking wastewater were prepared in the presence of formaldehyde. The phenolic resins were characterized by in-situ infrared and thermal analysis. The pyrolysis kinetic parameters obtained from analyzing thermogravimetric analysis data indicated that a mixture of phenolic compounds had higher crosslinking degree and the phenolic resin was more stable. This study provides a theoretical basis for optimizing of semicoking wastewater treatment by utilizing formaldehyde.
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Spatial Distribution of Earthquakes and Crustal Seismic Velocity in Shanxi Rift Zone
WANG Yu, LI Zihong, NING Jieyuan
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (2): 283-290.   DOI: 10.13209/j.0479-8023.2020.001
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To study the seismic activity and physical background of Shanxi rift zone, we use tomoDD to relocate earthquakes recorded by China network from 1990 to 2008 and the data recorded by a local network run by Shanxi Earthquake Bureau from 2012 to 2016, and show three-dimensional seismic velocity structure in Shanxi rift zone. The events are concentrated around the known faults in the Shanxi rift zone, mainly on the NE and SW sides of the Taiyuan Basin. Most of the focal depths are shallower than 30 kilometers. The earthquakes in the northern part of the research area are shallow while the earthquakes deeper than 20 kilometers are mainly located to the south of the Xinding Basin. Among them, the two densely distributed seismic zones on the NE and SW sides of the Taiyuan Basin with strikes pointing NS directions form sub-vertical distributed seismic zones, which may be controlled by two strike-slip deep fracture zones. If the Taiyuan Basin is broken and the two strike-slip faults are connected, there might be strong earthquakes with magnitude 7 or higher. The results show that the velocity in Shanxi Rift Zone varies intensely. The velocity in the crust of Shanxi Rift Zone is generally low, but the velocity in the crust of the Taiyuan Basin is not the lowest when the velocity in the crust of its NE and SW is especially low. In contrast, to the NW and SE of the Taiyuan Basin as well as the west of Datong the velocity in the crust is high. These correspond well with geological features on the surface and the heat flow observations. The results show that there might be thermal materials upwelling beneath the Shanxi Rift zones to NE and SW of the Taiyuan Basin and the hot materials might invade into the interior of the Ordos block. On the contrary, the hot materials most probably do not invade into the crust of the Taiyuan Basin, as well as its NW and SE surrounding areas. We deduce that the extension of the Taiyuan Basin might not be controlled by the upwelling of hot materials but be controlled by horizontal extensional force produced by the push of the Tibettan Plateau.
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Estimating the Daily Atmospheric Maximum Mixing Height with 1-Second Sounding Data over Beijing Area
WANG Yuehao, LI Chengcai, CHU Yiqi, TAN Wangshu, REN Jingjing
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (2): 223-230.   DOI: 10.13209/j.0479-8023.2019.129
Abstract1135)   HTML    PDF(pc) (807KB)(145)       Save
Basing on the 1-second sounding data from L-band radar and the daily max potential surface air temperature over Beijing, the possibility of deriving the daily maximum mixing layer height (MMH) over Beijing region by the parcel method was studied. By comparing the inversion results of the 1-second sounding data and the conventional sounding data at local time 08:00 with the inversion results from a micro pulse lidar (MPL), it is found that the consistency between the former and the MPL results is better than the latter. The reason for the larger bias from the conventional data results may be due to their lower vertical resolution. By comparing the inversion results of the 1-second sounding data in spring, summer, autumn and winter respectively with the results from the MPL, it is found that the consistency is better in spring, summer and autumn, but it is worse in winter. Long-term data results of the MMH over Beijing area from 2010 to 2017 were obtained using the 1-second sounding data at local time 08:00 and the daily maximum potential surface air temperature. It is found that the MMH almost showed a decreasing characteristic from spring to summer, to autumn and to winter successively. With the long-term results, it is found that the thermal stability defined by the difference of the daily max surface air temperature and temperature at the layer of 850 hPa was strongly positively correlated with the MMH in Beijing area.
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Determination and Influence of Solid Angle in High Accuracy Analysis
QIN Liqing, YAN Sha, ZHU Jipeng, GAO Yuan, XUE Jianming, WANG Yugang
Acta Scientiarum Naturalium Universitatis Pekinensis    2020, 56 (2): 199-205.   DOI: 10.13209/j.0479-8023.2020.009
Abstract1052)   HTML    PDF(pc) (1469KB)(237)       Save
In order to achieve high accuracy IBA (ion beam analysis), the calculation error of solid angle were discussed meticulously. The accuracies of face to point solid angle and approximate solid angle were calculated, based on face to face solid angle which contained area of beam spot. Based on 4.5 MV electrostatic accelerator ion beam target chamber of Peking University, solid angle influenced by distributions of cross-section and beam intensity was determined. A geometry-condition estimation for accuracy of approximate solid angle better than 1% was given and verified by two examples. For fatherly achievement of high-accuracy solid angle, accurate machining such as laser processing is required.
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Cognitive Appraisal and Meaning in Life in Recalling of Past Events: The Emotion as a Mediator
PANG Zhuoyue, ZHUANG Shujie, WANG Yuqian, GAN Yiqun
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (5): 977-986.   DOI: 10.13209/j.0479-8023.2019.069
Abstract891)   HTML    PDF(pc) (696KB)(272)       Save
The purpose of this paper is to investigate the relationship among cognitive appraisal, emotion and meaning in life when individuals recall past events. Before and after 171 college students’ writing on the same thing about the national college entrance examination, this study set a structural equation model to explore the mediation effect of emotion between cognitive appraisal and meaning in life. After the effect of gender, year, pretest of emotion and meaning in life were controlled, results indicated that positive appraisal and negative appraisal could predict meaning in life through positive emotion instead of negative emotion.
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Soil Temperature Triggers Sap Flow Onset and Offset of Pinus tabulaeformis
WANG Yue, YAN Chunhua, QIU Guoyu
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (3): 580-586.   DOI: 10.13209/j.0479-8023.2019.028
Abstract818)   HTML    PDF(pc) (2706KB)(145)       Save
TDP (thermal dissipation probe) technology was used for continuous observation and preliminary study of the secondary dominant tree species Pinus tabulaeformis in Jiuzhai Valley. A temperature sensor was used to collect soil temperature gradients from 2013 to 2015 with 6 depth gradients at 3, 10, 20, 30, 40, and 50 cm below the tree. The analysis showed that the temperature of surface soil in the shallow 3 cm soil layer in early spring had a stronger influence on the sap flow intensity than the deep soil temperature and air temperature (correlation coefficient was 0.852). The temperature gradient analysis reported that the optimum temperature for the root system was 4.0–7.9°C. With the increase of soil temperature, the characteristics of sap flow initiated by Pinus tabulaeformis in March and April would exacerbate the decrease of early spring runoff in Jiuzhai Valley. 
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Urban River Landscape Planning Based on Landscape Evaluation: A Case Study of Panlong River in Kunming
LIU Jiaju, WANG Yuhong, ZHAO Long, GUO Huaicheng
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (1): 189-196.   DOI: 10.13209/j.0479-8023.2018.093
Abstract738)   HTML    PDF(pc) (2633KB)(152)       Save

To construct the evaluation index system of urban river landscape, the landscape evaluation of the river is taken as the target level, and the eco-environmental index, social economy and aesthetics are taken as the guideline. Water quality, species diversity, water transparency, flood control, waterscape utilization, landscape accessibility, color beauty, form beauty, and regional culture are used as index layers. Analytic Hierarchy Process (AHP) is used to determine the weight of each indicator layer, and the use of distance index method is used to build the evaluation model. The evaluation model was used to evaluate the landscape of the upper and lower reaches of Panlong River in Kunming. The quantitative evaluation and qualitative evaluation are combined to provide guidance for planning and design of urban river system landscape environment and to build a new model of water restoration planning in order to provide reference for sustainable development.

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Ecological Tension Index Assessment in China Based on RBFN Model
WANG Yuqi, CHENG Shupeng, LU Wentao, FU Zhenghui, GUO Huaicheng
Acta Scientiarum Naturalium Universitatis Pekinensis    2019, 55 (1): 182-188.   DOI: 10.13209/j.0479-8023.2018.091
Abstract869)   HTML    PDF(pc) (1601KB)(206)       Save

This paper select related indexes of ecological tension to establish the RBFN (radial basis function network) model, which is trained and tested according to the research results of ecological tension at different time in different regions. Then, the model is used to evaluate ecological tension of China’s 31 provinces, autonomous regions and municipalities in 2008 and 2013, and the evaluation results visualization expressed with GIS. The results show that the half area is the ecological pressure security status, and Beijing has the largest ecological pressure all the time; 22 provincial administrative regions’ ecological tension are aggravated from 2008 to 2013; regionally, the ecological pressure is the largest in North China, and the smallest in the northwest.

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Improvements on Transient Power Law Model under HBM Stress
CAO Xin, CAO Jian, WANG Yize, WANG Yuan, ZHANG Xing
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (5): 946-950.   DOI: 10.13209/j.0479-8023.2018.044
Abstract699)   HTML    PDF(pc) (510KB)(87)       Save

An improved model is proposed based on the transient power law model under Human Body Model (HBM) stress. This model can predict the gate oxide breakdown statistically under HBM stress. Through HSPICE simulation tool, the corresponding DC effective voltage on the MOS can be calculated. The scatter chart of the precharge voltage of the HBM circuit with the effective DC voltages of the MOS shows a linear relationship. Using the Laplace transform, the linear relationship is proved. Compared with the existing transient power law model, the improved model reduces the computational complexity under the HBM stress and is easier to predict the MOS gate oxide breakdown statistically. The proposed model provides an important reference for the evaluation of the reliability of the MOS gate oxide under the impact of HBM.

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Leaf Stomatal Traits of Woody Plants and Their Response to Nitrogen Addition in Typical Forests in Eastern China
JIANG Xingxing, ZOU Anlong, WANG Yuanyuan, ZHOU Xuli, JI Chengjun
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (4): 839-847.   DOI: 10.13209/j.0479-8023.2018.003
Abstract571)   HTML    PDF(pc) (992KB)(182)       Save

The stomatal traits of eighteen dominant woody plants in the Nutrient Enrichment Experiments in Chinese Forests (NEECF) were compared. The results showed that the lifeform affects stomatal features of the woody plants significantly (P<0.05). There is a visible latitudinal pattern of stomatal traits of dominant woody plants in eastern China and MAT, MAP, PET are important influent factors. All woody plants’ stomatal traits have significant correlation. The stomatal length and density showed negative correlation, and the stomatal conductance increased with increasing stomatal length and decreased with increasing stomatal density. Woody plants of different climate zones and lifeform showed diverse response with nitrogen addition.

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Origin of Mg-Rich-Fluids and Dolomitization of Lower Ordovician Penglaiba Formation at Tongguzibulong Outcrop in the Northwestern Margin of Tarim Basin
HE Yong, LIU Bo, LIU Hongguang, SHI Kaibo, WANG Yuanchong, JIANG Weimin
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (4): 781-791.   DOI: 10.13209/j.0479-8023.2018.006
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Based on comprehensive analysis of field work, petrological and geochemical characteristics, the authors study the sources of dolomitizing fluids and the models of dolomitization of the Lower Ordovician Penglaiba Formation in Tongguzibulong Outcrop, the northwestern margin of Tarim Basin, China. Four types of
dolomite are recognized: euhedral-subhedral powder crystallized dolomite, euhedral-subhedral fine crystallized dolomite, subhedral-xenotopic medium crystallized dolomite and subhedral-xenotopic coarse crystallized dolomite. Powder-fine crystallized dolomite is distributed in the lower part of Penglaiba Formation, and has cloudy center surrounded by clear rim. With residual sand texture, inter-crystal pores and inter-partical pores, medium-coarse crystallized dolomite is distributed in the upper part of Penglaiba Formation. The REE patterns of dolomite and contemporaneous limestone rich in LREE and deplete in HREE, present a trait of unobvious Ce anomaly and Eu negative anomaly, the values of C-O isotope locate in the scope of contemporaneous marine dolomite, and Eu negative anomaly. All these denote that the dolomitizing fluid is normal or slightly concentrated seawater. Besides, Powder-fine crystallized dolomite present a low value of Fe, Mn and a high value of Sr, Ba, formed by reflux seepage dolomitization in penesaline seawater. Cloudy center surrounded by clear rim texture and multi-rimmed texture are the results of over-dolomitization. Medium-coarse crystallized dolomite with residual grain texture, interbedded with sand limestone, are controlled by high frequency sea level change. With a higher value of Fe, Mn and a lower value of Sr, Ba when compared with powder-fine crystallized dolomite, medium-coarse dolomite formed by the early reflux seepage dolomitization and intensified by the subsequent burial recrystallization.

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An Analysis Method of System-Level ESD Model with a TLP Stress Input
WANG Yize, WANG Yuan, CAO Jian, ZHANG Xing
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (2): 293-298.   DOI: 10.13209/j.0479-8023.2017.146
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Based on the existing equivalent formula of the transmission line pulse (TLP) and IEC 61000-4-2 stresses, the authors propose an analysis method of the system-level model with TLP stress as an input. Compared with the traditional analysis method under system-level IEC stress, the proposed method solves the issue that the calculation of the residual energy flowing into the device under test (DUT) is not accurate enough. Meanwhile, the prediction ability for the failure of the DUT is promoted. This work predicts the failure of the DUT under the mentioned two stresses through SPICE simulation. Furthermore, this work shows the validation through the measured results of the relevant printed circuit boards (PCBs), which confirms the promotion of the aforesaid prediction ability.

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Survey Research on Residential Building Energy Consumption in Urban and Rural Area of China
WANG Yue, ZHAO Pengjun
Acta Scientiarum Naturalium Universitatis Pekinensis    2018, 54 (1): 162-170.   DOI: 10.13209/j.0479-8023.2017.159
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Based on the questionnaire of 10 cities and towns in China, this research has found that there are significant differences between urban and rural area in China through the data analyzing. The survey mainly includes five aspects: energy consumption for heating and cooling, lighting energy consumption, household electricity appliances’ energy consumption, and the energy consumption for cooking. The findings show that the main energy resource are electricity, natural gas and coal and the main energy consuming activities are heating, cooking and household electricity appliances’ consumption. In addition, the results of survey reflect the difference in energy source and consumption structure between urban and rural area. Generally, the per capita energy consumption in urban is 3.2 times of rural life. Gas and electricity are the main energy source in urban area while electricity power and coal have a high proportion in rural residents. The survey results provide important reference for China to implement energy saving policy.

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Development of Multi-energies NRA Methods for Depth Profiling of Deuterium Based on 4.5 MV Electrostatic Accelerator in Peking University
XIAO Xuan, YAN Sha, ZHU Jipeng, GAO Yuan, XUE Jianming, WANG Yugang
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (5): 767-775.   DOI: 10.13209/j.0479-8023.2015.129
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To fulfill the need of studying the deuterium retention in nuclear materials, the authors set up an NRA to analyze device with three channel detecting system based on 4.5 MV electrostatic accelerator in Peking University, and developed a multi-energies NRA method for quantitative depth profiling deuterium. With the simultaneous energy spectra of p and 4He created by the D (3He, p) 4He nuclear reaction, by adopting several different incident 3He+ energies (0.8?3.6 MeV), a reasonable better depth resolution and higher sensitivity in a larger analyzing depth could be obtained. The authors also measured differential cross-section of the 3He-D reaction at 135°. The relative accuracy of these data was better than ±3.9%. The initial measurement of concentration and depth profiles of D was carried out, using targets of implanted PC-W samples, as well as CMSIIW samples from a W-coated outer divertor tile of TOKAMAK AUG near the strike points. A ~6 μm analyzed depth could be obtained with a depth resolution less than 1.5 μm throughout the whole detecting range and a ~20 nm minimal resolution at the sample surfaces. The detection limit was around 5×1019 D/m2. Apart from the statistical and fitting error of NRA spectra, the NRA system had an experimental error of ±7.5% from the parameter measurement.

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Approximate Lie Symmetries, Approximate Noether Symmetries and Approximate Mei Symmetries of Typical Perturbed Mechanical System
LOU Zhimei, WANG Yuanbin, XIE Zhikun
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (4): 681-686.   DOI: 10.13209/j.0479-8023.2016.080
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Three methods, which are approximate Lie symmetry method, approximate Noether symmetry method and approximate Mei symmetry method, are adopted to study the first order approximate symmetries and approximate conserved quantities of a typical perturbed mechanical system. Six identical first order approximate symmetries and approximate conserved quantities of the typical perturbed mechanical system are obtained by approximate Lie symmetry method and approximate Noether symmetry method, but only five of them can be obtained by approximate Mei symmetry method.

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Mechanism from Absence of Meaning to Meaning in Life: Moderated Mediation of Satisfaction of Psychological Need
WANG Yu, CHEN Weiyi, GAN Yiqun
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (3): 581-586.   DOI: 10.13209/j.0479-8023.2016.031
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This study aimed to explore the mediation effect of search for meaning between absence of meaning and meaning in life, and tested the role of satisfaction of psychological need in this process via two-wave data. The sample consisted of 156 university students. Participants reported absence of meaning, search for meaning and psychological need satisfaction at time 1 and reported meaning in life at time 2. Results indicated that search for meaning played a partial mediating role between absence of meaning and meaning in life, and psychological need satisfaction moderated relationship between meaning thinking and meaning in life. Under low-level of psychological need satisfaction, search for meaning was strongly associated with meaning in life. With increased satisfaction of psychological need, positive effect of search for meaning on meaning in life become insignificant.

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The Characteristics and Implication of Origin of the Giant Patch Dolomite of the Lower-Middle Ordovician in Wuligezitag Area NE Tarim Basin, China
WU Shuanglin, SHI Kaibo, LIU Hongguang, LIU Jianqiang, WANG Yuxi, LIU Bo
Acta Scientiarum Naturalium Universitatis Pekinensis    2016, 52 (3): 444-456.   DOI: 10.13209/j.0479-8023.2015.118
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Based on comprehensive analysis of field work, petrological and geochemical characteristics, this paper studies the characteristics and origin of giant patch dolomite of the Lower-Middle Ordovician HangGuletag Formation in Wuligezitag area, NE Tarim Basin, China. It can be seen in the field that the grayish yellow giant patch dolomite partially develops in the black thin-bedded micritic limestone, with an irregular boundary not controlled by sedimentation. The giant patches are several meters in size (the largest >10 m) which is larger than and quite different from the several-centimeter (decimeter) burrow-related dolomite or leopard fur dolomite. Microscopically, it consists of micro-finely and planare(s) dolomite crystals with a size near 100 μm. Besides, it is also characterized by its unique geochemical features: 1) δ13CPDB (−1.34‰-−0.62‰) accords with the range of Early Ordovician seawater while δ18OPDB (−8.01‰ -−4.79‰) is higher; 2) 87Sr/86Sr  (0.711000-0.711535, AVG=0.710863) is much higher than that of limestone and contemporaneous seawater; 3) average high Fe and Mn content (2001.32 and 601.73 μg/g, respectively) and low Sr and Ba (33.14 and 8.27 μg/g, respectively) content versus that of limestone; 4) dolomite has slightly negative Eu anomaly and similar REE composition and distribution patterns compared with limestone; 5) low order degree value (AVG=0.6). This study reveals that the dolomitization was related to fault and occurred in low-temperature and shallow-burial environment in Early-Middle Ordovician. Dolomitizing fluid was generated from the concentrated formation fluid in lower-middle member of HangGuletag Formation and underlying Tursaktag Group. Most Mg2+ came from the stabilization of quasi-stable carbonate minerals, and the transformation of clay minerals of (calcareous) mud in the limestone strata not only provided a little Mg2+ but caused the rise of 87Sr/86Sr. Dolomitizing fluid was likely to be richened in Xingdi-related normal fault and fractures which also acted as the main fluid pathways, and it finally caused the partial dolomitization of nearby limestone strata.

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