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1. chinaXiv:202109.00013 [pdf]

Synergistic effects of multiple driving factors on the runoff variations in the Yellow River Basin, China

WANG Junjie; SHI Bing; ZHAO Enjin; CHEN Xuguang; YANG Shaopeng
Subjects: Geosciences >> Geography

River runoff plays an important role in watershed ecosystems and human survival, and it is controlled by multiple environmental factors. However, the synergistic effects of various large-scale circulation factors and meteorological factors on the runoff on different time-frequency scales have rarely been explored. In light of this, the underlying mechanism of the synergistic effects of the different environmental factors on the runoff variations was investigated in the Yellow River Basin of China during the period 1950–2019 using the bivariate wavelet coherence (WTC) and multiple wavelet coherence (MWC) methods. First, the continuous wavelet transform (CWT) method was used to analyze the multiscale characteristics of the runoff. The results of the CWT indicate that the runoff exhibited significant continuous or discontinuous annual and semiannual oscillations during the study period. Scattered inter-annual time scales were also observed for the runoff in the Yellow River Basin. The meteorological factors better explained the runoff variations on seasonal and annual time scales. The average wavelet coherence (AWC) and the percent area of the significant coherence (PASC) between the runoff and individual meteorological factors were 0.454 and 19.89%, respectively. The circulation factors mainly regulated the runoff on the inter-annual and decadal time scales with more complicated phase relationships due to their indirect effects on the runoff. The AWC and PASC between the runoff and individual circulation factors were 0.359 and 7.31%, respectively. The MWC analysis revealed that the synergistic effects of multiple factors should be taken into consideration to explain the multiscale characteristic variations of the runoff. The AWC or MWC ranges were 0.320–0.560, 0.617–0.755, and 0.819–0.884 for the combinations of one, two, and three circulation and meteorological factors, respectively. The PASC ranges were 3.53%–33.77%, 12.93%–36.90%, and 20.67%–39.34% for the combinations one, two, and three driving factors, respectively. The combinations of precipitation, evapotranspiration (or the number of rainy days), and the Arctic Oscillation performed well in explaining the variability in the runoff on all time scales, and the average MWC and PASC were 0.847 and 28.79%, respectively. These findings are of great significance for improving our understanding of hydro-climate interactions and water resources prediction in the Yellow River Basin.

submitted time 2021-09-08 From cooperative journals:《Journal of Arid Land》 Hits5379Downloads398 Comment 0

2. chinaXiv:202103.00131 [pdf]

Direct-writing of two-dimensional diodes by focused ion beams

Tan Yang
Subjects: Physics >> Interdisciplinary Physics and Related Areas of Science and Technology

In the past decade, electronic devices based on graphene and the related two-dimensional (2D) materials have exhibited outstanding figures of merit. However, so far, the fabrication of two-dimensional diodes, as elementary building blocks of electronic devices, still relies on manual or semi-automated handling processing. To unleash their commercial potential, the integration of 2D materials into a fully-automated fabrication line is a critical step. Here, we elucidate the focused ion-beam writing as an automated approach to construct lateral diodes on a 2D heterostructure (MoSe2/G) consisting of the stacked monolayer graphene and MoSe2. Se-defects generated by focused ion writing endow the 2D heterostructure with unique electronic properties like the adjustable work function and the quasi-metallic state, which allows for the construction of the barrier at the boundary of the writing and non-writing region. Benefiting from this feature, the ion-beam-written heterostructure is used to realize rectifying and current regulating diodes. Exhibiting comparable performance to traditional diodes, the rectifying diode has a rectification ratio of ~104, while the current regulative diode has a dynamic resistance larger than 4.5 MΩ. Furthermore, to illustrate practical applications of these diodes in digital logic electronics, AND and OR logic gates are directly inscribed on the heterostructure by ion beams. Our work demonstrates the focused ion-beam writing as an additional strategy for direct-writing of 2D diodes on graphene-based heterostructures.

submitted time 2021-03-24 Hits7980Downloads877 Comment 0

3. chinaXiv:202005.00090 [pdf]

Spatial and temporal change patterns of net primary productivity and its response to climate change in the Qinghai–Tibet Plateau of China from 2000 to 2015

GUO Bing; ZANG Wenqian6, YANG Fei; HAN Baomin; CHEN Shuting; LIU Yue; YANG Xiao; HE Tianli; CHEN Xi; LIU Chunting; GONG Rui
Subjects: Biology >> Botany >> Applied botany

The vegetation ecosystem of the Qinghai–Tibet Plateau in China, considered to be the ′′natural laboratory′′ of climate change in the world, has undergone profound changes under the stress of global change. Herein, we analyzed and discussed the spatial-temporal change patterns and the driving mechanisms of net primary productivity (NPP) in the Qinghai–Tibet Plateau from 2000 to 2015 based on the gravity center and correlation coefficient models. Subsequently, we quantitatively distinguished the relative effects of climate change (such as precipitation, temperature and evapotranspiration) and human activities (such as grazing and ecological construction) on the NPP changes using scenario analysis and Miami model based on the MOD17A3 and meteorological data. The average annual NPP in the Qinghai–Tibet Plateau showed a decreasing trend from the southeast to the northwest during 2000–2015. With respect to the inter-annual changes, the average annual NPP exhibited a fluctuating upward trend from 2000 to 2015, with a steep increase observed in 2005 and a high fluctuation observed from 2005 to 2015. In the Qinghai–Tibet Plateau, the regions with the increase in NPP (change rate higher than 10%) were mainly concentrated in the Three-River Source Region, the northern Hengduan Mountains, the middle and lower reaches of the Yarlung Zangbo River, and the eastern parts of the North Tibet Plateau, whereas the regions with the decrease in NPP (change rate lower than –10%) were mainly concentrated in the upper reaches of the Yarlung Zangbo River and the Ali Plateau. The gravity center of NPP in the Qinghai–Tibet Plateau has moved southwestward during 2000–2015, indicating that the increment and growth rate of NPP in the southwestern part is greater than those of NPP in the northeastern part.Further, a significant correlation was observed between NPP and climate factors in the Qinghai–Tibet Plateau. The regions exhibiting a significant correlation between NPP and precipitation were mainly located in the central and eastern Qinghai–Tibet Plateau, and the regions exhibiting a significant correlation between NPP and temperature were mainly located in the southern and eastern Qinghai–Tibet Plateau. Furthermore, the relative effects of climate change and human activities on the NPP changes in the Qinghai–Tibet Plateau exhibited significant spatial differences in three types of zones, i.e., the climate change-dominant zone, the human activity-dominant zone, and the climate change and human activity interaction zone. These research results can provide theoretical and methodological supports to reveal the driving mechanisms of the regional ecosystems to the global change in the Qinghai–Tibet Plateau.

submitted time 2020-05-31 From cooperative journals:《Journal of Arid Land》 Hits12829Downloads1400 Comment 0

4. chinaXiv:202004.00050 [pdf]

Spatial and temporal change patterns of net primary productivity and its response to climate change in the Qinghai–Tibet Plateau of China from 2000 to 2015

GUO Bing; ZANG Wenqian; YANG Fei; HAN Baomin; CHEN Shuting; LIU Yue; YANG Xiao; HE Tianli; CHEN Xi; LIU Chunting; GONG Rui
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology

The vegetation ecosystem of the Qinghai–Tibet Plateau in China, considered to be the ′′natural laboratory′′ of climate change in the world, has undergone profound changes under the stress of global change. Herein, we analyzed and discussed the spatial-temporal change patterns and the driving mechanisms of net primary productivity (NPP) in the Qinghai–Tibet Plateau from 2000 to 2015 based on the gravity center and correlation coefficient models. Subsequently, we quantitatively distinguished the relative effects of climate change (such as precipitation, temperature and evapotranspiration) and human activities (such as grazing and ecological construction) on the NPP changes using scenario analysis and Miami model based on the MOD17A3 and meteorological data. The average annual NPP in the Qinghai–Tibet Plateau showed a decreasing trend from the southeast to the northwest during 2000–2015. With respect to the inter-annual changes, the average annual NPP exhibited a fluctuating upward trend from 2000 to 2015, with a steep increase observed in 2005 and a high fluctuation observed from 2005 to 2015. In the Qinghai–Tibet Plateau, the regions with the increase in NPP (change rate higher than 10%) were mainly concentrated in the Three-River Source Region, the northern Hengduan Mountains, the middle and lower reaches of the Yarlung Zangbo River, and the eastern parts of the North Tibet Plateau, whereas the regions with the decrease in NPP (change rate lower than –10%) were mainly concentrated in the upper reaches of the Yarlung Zangbo River and the Ali Plateau. The gravity center of NPP in the Qinghai–Tibet Plateau has moved southwestward during 2000–2015, indicating that the increment and growth rate of NPP in the southwestern part is greater than those of NPP in the northeastern part. Further, a significant correlation was observed between NPP and climate factors in the Qinghai–Tibet Plateau. The regions exhibiting a significant correlation between NPP and precipitation were mainly located in the central and eastern Qinghai–Tibet Plateau, and the regions exhibiting a significant correlation between NPP and temperature were mainly located in the southern and eastern Qinghai–Tibet Plateau. Furthermore, the relative effects of climate change and human activities on the NPP changes in the Qinghai–Tibet Plateau exhibited significant spatial differences in three types of zones, i.e., the climate change-dominant zone, the human activity-dominant zone, and the climate change and human activity interaction zone. These research results can provide theoretical and methodological supports to reveal the driving mechanisms of the regional ecosystems to the global change in the Qinghai–Tibet Plateau.

submitted time 2020-04-23 From cooperative journals:《Journal of Arid Land》 Hits1288Downloads708 Comment 0

5. chinaXiv:201711.02280 [pdf]

The Application of SNiPER to the JUNO Simulation

Tao Lin; Jiaheng Zou; Weidong Li; Ziyan Deng; Xiao Fang; Guofu Cao; Xingtao Huang; Zhengyun You
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The JUNO (Jiangmen Underground Neutrino Observatory) is a multipurpose neutrino experiment which is designed to determine neutrino mass hierarchy and precisely measure oscillation parameters. As one of the important systems, the JUNO o ine software is being developed using the SNiPER software. In this proceeding, we focus on the requirements of JUNO simulation and present the working solution based on the SNiPER. The JUNO simulation framework is in charge of managing event data, detector geometries and materials, physics processes, simulation truth information etc. It glues physics generator, detector simulation and electronics simulation modules together to achieve a full simulation chain. In the implementation of the framework, many attractive characteristics of the SNiPER have been used, such as dynamic loading, exible ow control, multiple event management and Python binding. Furthermore, additional e orts have been made to make both detector and electronics simulation exible enough to accommodate and optimize di erent detector designs. For the Geant4-based detector simulation, each sub-detector component is implemented as a SNiPER tool which is a dynamically loadable and con gurable plugin. So it is possible to select the detector con guration at runtime. The framework provides the event loop to drive the detector simulation and interacts with the Geant4 which is implemented as a passive service. All levels of user actions are wrapped into di erent customizable tools, so that user functions can be easily extended by just adding new tools. The electronics simulation has been implemented by following an event driven scheme. The SNiPER task component is used to simulate data processing steps in the electronics modules. The electronics and trigger are synchronized by triggered events containing possible physics signals. The JUNO simulation software has been released and is being used by the JUNO collaboration to do detector design optimization, event reconstruction algorithm development and physics sensitivity studies.

submitted time 2017-11-10 Hits892Downloads518 Comment 0

6. chinaXiv:201609.00986 [pdf]

Associated Production of Higgs Boson and $t\bar t$ at LHC

Hong-Lei Li; Peng-Cheng Lu; Zong-Guo Si; Ying Wang
Subjects: Physics >> Nuclear Physics

One of the future goals of the LHC is to precisely measure the properties of Higgs boson. The associated production of Higgs boson and the top quark pair is a promising process to investigate the related Yukawa interaction and the properties of Higgs. Compared with the pure scalar sector in the Standard Model, the Higgs sector contains both scalar and pseudoscalar in many new physics models, which makes the t ?tH interaction more complex and provides a variety of phenomena. To investigate thet ?tH interaction and the properties of Higgs, we study the top quark spin correlation observables at the LHC.

submitted time 2016-09-14 Hits574Downloads303 Comment 0

7. chinaXiv:201609.00945 [pdf]

Studying color connection effects of $e^+e^- \to c\barcc\barc \to \Xi_cc+X $ process within Quark Combination Model

Y. Jin; H. L. Li; S. Q. Li; S. Y. Li; Z. G. Si; T. Yao; X. F. Zhang
Subjects: Physics >> Nuclear Physics

The color connection of the parton system is an important bridge to connect the perturbative process and the hadronization one. The special color connection of four-heavy-quark system in?e+e??annihilation, which is the necessary one for the doubly heavy baryon and tetraquark productions is revisited. The hadronization effects, investigated with the help of the Quark Combination Model are compared with the corresponding results employing the Lund String Model in our previous work. The global properties related to a certain color connection are not sensitive to various hadronization models.

submitted time 2016-09-13 Hits466Downloads207 Comment 0

8. chinaXiv:201609.00871 [pdf]

Development of Yangbajing air shower core detector array for a new EAS hybrid experiment

LIU Jin-Sheng; HUANG Jing; CHEN Ding; ZHZNG Ying; ZHAI Liu-Ming; CHEN Xu; HU Xiao-Bin; LIN Yu-Hui; ZHANG Xue-Yao; FENG Cun-Feng; JIA Huan-Yu; ZHOU Xun-Xiu; ANZENGLUOBU; CHEN Tian-Lu; LI Hai-Jin; LIU Mao-Yuan; YUAN Ai-Fang
Subjects: Physics >> Nuclear Physics

Aiming at the observation of cosmic-ray chemical composition at the "knee" energy region, we have been developinga new type air-shower core detector (YAC, Yangbajing Air shower Core detector array) to be set up at Yangbajing (90.522??E, 30.102??N, 4300 m above sea level, atmospheric depth: 606 g/m2) in Tibet, China. YAC works together with the Tibet air-shower array (Tibet-III) and an underground water cherenkov muon detector array (MD) as a hybrid experiment. Each YAC detector unit consists of lead plates of 3.5 cm thick and a scintillation counter which detects the burst size induced by high energy particles in the air-shower cores. The burst size can be measured from 1 MIP (Minimum Ionization Particle) to?106?MIPs. The first phase of this experiment, named "YAC-I", consists of 16 YAC detectors each having the size 40 cm?×?50 cm and distributing in a grid with an effective area of 10 m2. YAC-I is used to check hadronic interaction models. The second phase of the experiment, called "YAC-II", consists of 124 YAC detectors with coverage about 500 m2. The inner 100 detectors of 80 cm?×?50 cm each are deployed in a 10?×?10 matrix from with a 1.9 m separation and the outer 24 detectors of 100 cm?×?50 cm each are distributed around them to reject non-core events whose shower cores are far from the YAC-II array. YAC-II is used to study the primary cosmic-ray composition, in particular, to obtain the energy spectra of proton, helium and iron nuclei between 5×1013?eV and?1016?eV covering the "knee" and also being connected with direct observations at energies around 100 TeV. We present the design and performance of YAC-II in this paper.

submitted time 2016-09-13 Hits1423Downloads806 Comment 0

9. chinaXiv:201608.00216 [pdf]

Performance of new 8-inch photomultiplier tube used for the Tibet muon-detector array

Ying Zhang; Jing Huang; Ding Chen; Liu-Ming Zhai; Xu Chen; Xiao-Bin Hu; Yu-Hui Lin; Hong-Bo Jin; Xue-Yao Zhang; Cun-Feng Feng: Huan-Yu Jia; Xun-Xiu Zhou; DANZENGLUOBU; Tian-Lu Chen; LABACIREN; Mao-Yuan Liu; Qi Gao; ZHAXICIREN
Subjects: Physics >> Nuclear Physics

A new hybrid experiment has been constructed to measure the chemical composition of cosmic rays around the "knee" in the wide energy range by the Tibet ASγ?collaboration at Tibet, China, since 2014. They consist of a high-energy air-shower-core array (YAC-II), a high-density air-shower array (Tibet-III) and a large underground water-Cherenkov muon-detector array (MD). In order to obtain the primary proton, helium and iron spectra and their "knee" positions in the energy range lower than?1016?eV, each of PMTs equipped to the MD cell is required to measure the number of photons capable of covering a wide dynamic range of 100 -?106?photoelectrons (PEs) according to Monte Carlo simulations. In this paper, we firstly compare the characteristic features between R5912-PMT made by Japan Hamamatsu and CR365-PMT made by Beijing Hamamatsu. This is the first comparison between R5912-PMT and CR365-PMT. If there exists no serious difference, we will then add two 8-inch-in-diameter PMTs to meet our requirements in each MD cell, which are responsible for the range of 100 - 10000 PEs and 2000 - 1000000 PEs, respectively. That is, MD cell is expected to be able to measure the number of muons over 6 orders of magnitude.

submitted time 2016-08-31 Hits1597Downloads978 Comment 0

10. chinaXiv:201608.00214 [pdf]

Sensitivity of YAC to measure the light-component spectrum of primary cosmic rays at the 'knee' energies

L M Zhai; J Huang; D Chen M Shibata; Y Katayose; Ying Zhang; J S Liu; Xu Chen; X B Hu; Y H Lin
Subjects: Physics >> Nuclear Physics

A new air-shower core-detector array (YAC : Yangbajing Air-shower Core-detector array) has been developed to measure the primary cosmic-ray composition at the "knee" energies in Tibet, China, focusing mainly on the light components. The prototype experiment (YAC-I) consisting of 16 detectors has been constructed and operated at Yangbajing (4300 m a.s.l.) in Tibet since May 2009. YAC-I is installed in the Tibet-III AS array and operates together. In this paper, we performed a Monte Carlo simulation to check the sensitivity of YAC-I+Tibet-III array to the cosmic-ray light component of cosmic rays around the knee energies, taking account of the observation conditions of actual YAC-I+Tibet-III array. The selection of light component from others was made by use of an artificial neural network (ANN). The simulation shows that the light-component spectrum estimated by our methods can well reproduce the input ones within 10\% error, and there will be about 30\% systematic errors mostly induced by the primary and interaction models used. It is found that the full-scale YAC and the Tibet-III array is powerful to study the cosmic-ray composition, in particular, to obtain the energy spectra of protons and helium nuclei around the knee energies.

submitted time 2016-08-31 Hits1473Downloads853 Comment 0

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