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Synthetic data generation by diffusion models

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National Science Review 2024年第8期11卷 19-21页

作者： jun zhu Department of Computer Science and Technology BNRist Center Tsinghua-Bosch Joint ML CenterTsinghua University Pazhou Laboratory (Huangpu)

Sufficient and high-quality data are a prerequisite for building complex machine learning systems, especially those with a large number of parameters (e.g., ChatGPT). However, it is typically challenging or even impossible to acquire a sufficient amount of real data to train such systems. For example, auto-driving systems may need to learn from various accidental events in order to be reliable in driving, while collecting such real data is difficult or ethically infeasible.

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Soil pressure and pore pressure for seismic design of tunnels revisited: considering water-saturated, poroelastic half-space

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Earthquake Engineering and Engineering Vibration 2020年第1期19卷 17-36页

作者： zhu jun Liang Jianwen State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300354China School of Civil Engineering Tianjin UniversityTianjin 300354China

This paper describes a systematic study on the fundamental features of seismic soil pressure on underground tunnels, in terms of its magnitude and distribution, and further identifi es the dominant factors that signifi cantly infl uence the seismic soil pressure. A tunnel embedded in water-saturated poroelastic half-space is considered, with a large variety of model and excitation parameters. The primary features of both the total soil pressure and the pore pressure are investigated. Taking a circular tunnel as an example, the results are presented using a fi nite element-indirect boundary element(FE-IBE) method, which can account for dynamic soil-tunnel interaction and solid frame-pore water coupling. The effects of tunnel stiffness, tunnel buried depth and input motions on the seismic soil pressure and pore pressure are also examined. It is shown that the most crucial factors that dominate the magnitude and distribution of the soil pressure are the tunnel stiffness and dynamic soil-tunnel interaction. Moreover, the solid frame-pore water coupling has a prominent infl uence on the magnitude of the pore pressure. The fi ndings are benefi cial to obtain insight into the seismic soil pressure on underground tunnels, thus facilitating more accurate estimation of the seismic soil pressure.

关键词： seismic soil pressure seismic pore pressure dynamic soil-tunnel interaction water-saturated poroelastic

Effect of Au film pre-deposited at different durations as inner electrode on the electrical properties and interface microstructures of Na_2O-PbO-Nb_2O_5-SiO_2 multi-layer glass-ceramic capacitors

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Acta Metallurgica Sinica(English Letters) 2011年第6期24卷 449-456页

作者： jun zhu jun LUO Qingmeng ZHANG jun DU Advanced Electronic Materials Institute General Research Institute for Nonferrous Metals Beijing 100088 China

To further study the effect of sputtered Au film as transition electrode layer on the electrical properties and interface microstructures of Na20-PbO-Nb2O5-SiO2 multilayer glass-ceramic capacitors, Au films pre-deposited at different time were prepared by DC magnetron sputtering. Compared with the single paste electrode structure, samples with Au films pre-deposited from 6 to 18 min have the consistent perfor- mance to effectively improve the electrical properties of the capacitors, resulting in the doubled breakdown strength, an increase of equivalent capacitance by 22% and a decrease of leakage current by an order of magnitude. SEM observations indicate that the Au films with deposition time from 6 to 18 min would all help the formation of a dense electrode/dielectric interface and inhibit the diffusion of Ag. The results reveal that Au film pre-deposited for 6 min as inner electrode was sufficient to improve the interface microstructure and therefore to inhibit the Ag diffusion and enhance the overall performance of the multi-layer glass-ceramic capacitors.

关键词： Inner electrode Deposition time Glass-ceramic Multi-layer capacitor

Influence of baryons on the spatial distribution of matter:higher order correlation functions

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Research in Astronomy and Astrophysics 2012年第12期12卷 1603-1612页

作者： Xiao-jun zhu jun Pan Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 China National Astronomical Observatories Chinese Academy of Sciences B eijing 100012 China

Physical processes involving baryons could leave a non-negligible imprint on the distribution of cosmic matter.A series of simulated data sets at high resolution with identical initial conditions are employed for count-in-cell analysis,including one N-body pure dark matter run,one with only adiabatic gas and one with dissipative *** and higher order cumulants Sn of dark matter and gas are *** is found that physical processes with baryons mainly affect distributions of dark matter at scales less than 1 h-1 *** comparison with the pure dark matter run,adiabatic processes alone strengthen the variance of dark matter by～10%at a scale of 0.1 h-1 Mpc,while the Sn parameters of dark matter only mildly deviate by a few *** dissipative gas run does not differ much from the adiabatic run in terms of variance for dark matter,but renders significantly different Sn parameters describing the dark matter,bringing about a more than 10%enhancement to S3 at 0.1 h-1 Mpc and z=0 and being even larger at a higher *** patterns of gas in two hydrodynamical simulations are quite *** of gas at z=0 decreases by～30%in the adiabatic simulation but by～60%in the nonadiabatic simulation at 0.1 h-1 *** attenuation is weaker at larger scales but is still obvious at～10 h-1 *** parameters of gas are biased upward at scales 〈～4 h-1 Mpc,and dissipative processes show an～84%promotion at z=0 to S3 at 0.1 h-1 Mpc in contrast with the～7%change in the adiabatic *** segregation in clustering between gas and dark matter could have dramatic implications on modeling distributions of galaxies and relevant cosmological applications demanding fine details of matter distribution in a strongly nonlinear regime.

关键词： cosmology:dark matter-large-scale structure of universe-methods: statistical

Two Notes on Measure-Theoretic Entropy of Random Dynamical Systems

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Acta Mathematica Sinica,English Series 2009年第6期25卷 961-970页

作者： Yu jun zhu College of Mathematics and Information Science Hebei Normal University Shijiazhuang 050016 P. R. China

In this paper, Brin-Katok local entropy formula and Katok＇s definition of the measuretheoretic entropy using spanning set are established for the random dynamical system over an invertible ergodic system.

关键词： random dynamical system measure-theoretic entropy local entropy

Variation in glucosinolates in pak choi cultivars and various organs at different stages of vegetative growth during the harvest period

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2013年第4期14卷 309-317页

作者： Biao zhu Jing YANG zhu-jun zhu Department of Horticulture Zhejiang University School of Agricultural and Food Science Zhejiang Agricultural & Forestry University

Glucosinolates(GSs) play an important role in plant defense systems and human *** investigated the content and composition of GSs in the shoots and roots of seven cultivars of pak *** found that 'Si Yue Man' had the highest total and aliphatic GS contents in the shoots and the highest benzenic GS content in the roots,'Shanghai Qing' contained the highest amounts of benzenic and total GS contents in the roots,while 'Nanjing Zhong Gan Bai' had the lowest benzenic,indole,and total GS contents in both the shoots and ***,the 'Si Yue Man' cultivar appears to be a good candidate for future *** between the shoots and roots was also examined,and a significant correlation among the total,aliphatic,and some individual GSs was found,which is of value in agricultural *** concentrations of the leaf,petiole,and root increased dramatically during the period of rapid growth of the dry matter of the plant 10 to 20 d after transplantation,reaching peak values on Day 20 and decreasing on Day *** conclude that the pak choi should be harvested and consumed from 20 to 25 d after transplantation to take advantages of the high GS content in the plant.

关键词： Glucosinolate Pak choi Cultivar Organ Growth stage

Control factors of partial nitritation for landfill leachate treatment

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Journal of Environmental Sciences 2007年第5期19卷 523-529页

作者： LIANG zhu LIU jun-xin State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Science Chinese Academy of Sciences Beijing 100085 China

Anaerobic ammonium oxidation （ANAMMOX） technology has potential technical superiority and economical efficiency for the nitrogen removal from landfill leachate, which contains high-strength ammonium nitrogen （NH4^＋-N） and refractory organics. To complete the ANAMMOX process, a preceding partial nitritation step to produce the appropriate ratio of nitrite/ammonium is a key stage. The objective of this study was to determine the optimal conditions to acquire constant partial nitritation for landfill leachate treatment, and a bench scale fixed bed bio-film reactor was used in this study to investigate the effects of the running factors on the partial nitritation. The results showed that both the dissolved oxygen （DO） concentration and the ammonium volumetric loading rate （Nv） had effects on the partial nitritation. In the controlling conditions with a temperature of 30±1℃, Nv of 0.2-1.0 kg NH4＋-N/（m^3·d）, and DO concentration of 0.8-2.3 mg/L, the steady partial nitritation was achieved as follows： more than 94% partial nitritation efficiency （nitrite as the main product）, 60%-74% NH4^＋-N removal efficiency, and NO2^--N/NH4^＋-N ratio （concentration ratio） of 1.0-1.4 in the *** impact of temperature was related to Nv at certain DO concentration, and the temperature range of 25-30℃ was suitable for treating high strength ammonium leachate. Ammonium-oxidizing bacteria （AOB） could be acclimated to higher FA （free ammonium） in the range of 122-224 mg/L. According to the denaturing gradient gel electrophoresis analysis result of the bio-film in the reactor, there were 25 kinds of 16S rRNA gene fragments, which indicated that abundant microbial communities existed in the bio-film, although high concentrations of ammonium and FA may inhibit the growth of the nitrite-oxidizing bacteria （NOB） and other microorganisms in the reactor.

关键词： landfill leachate biological nitrogen removal partial nitritation ANAMMOX

Recent advances in direct dehydrogenative biphenyl couplings

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Science China Chemistry 2017年第6期60卷 701-720页

作者： Fei Lv zhu-jun Yao State Key Laboratory of Coordination Chemistry School of Chemistry and Chemical EngineeringCollaborative Innovation Center of Chemistry for Life ScieneesNanjing UniversityNanjing 210023China

Biphenyl moiety represents a unique structural motif of many natural and unnatural products with biological interests, and dehydrogenative couplings of two aryl C–H bonds under oxidative conditions is unambiguously the most efficient and direct preparation of these compounds. However, higher oxidation potential of benzene derivatives makes such oxidative couplings much more difficult than other arenes. Only very limited advances have been achieved on direct formation of the crucial C–C bond between two phenyl derivatives by dehydrogenative phenyl coupling in the last two decades. This article briefly summarized and commented a number of representative recent achievements in this attractive field, including homo-, cross-and intramolecular rearrangement and couplings, as well as their applications in organic synthesis.

关键词： biphenyl dehydrogenative coupling oxidation arene C–H bond activation

Preliminary study on active features of Fenghuang-shan-Tianshui fault, West Qinling north boundary fault zone since the late of Late Pleistocene

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Acta Seismologica Sinica(English Edition) 2001年第2期14卷 230-233页

作者： HAN zhu-jun Institute of Geology China Seismological Bureau Beijing China

West Qinling north boundary fault zone (WQNBFZ) is a major NWW-striking fault in the east boundary of Tibetan Plateau, which is parallel to the Xianshuihe fault zone, Eastern Kunlun fault zone and Haiyuan fault zone. It is of mainly sinistral strike-slip. England and Molnar (1990) and WANG and MA (1998) proposed that these strike-slip faults divided the east part of Tibetan Plateau into elongate blocks, which slide successively towards the east, accompanied possibly by the clockwise rotation. What is more, the occurrence frequency of earthquakes with M 36.5 along WQNBFZ is also high, such as BC 47 Zhangxian M=6.8 earthquake, the 128 Gangu M=6.5 earth-quake, the 143 Gangu M=7 earthquake, the 734 Tianshui M=7 earthquake, the 1756 Wushan M=6.5 earthquake and the 1936 Kangle M=6.8 earthquake. However, compared with researches on Haiyuan fault zone, Xianshuihe fault zone and Longmenshan fault zone (Institute of Geology of State Seismological Bureau, Seismological Bureau of Ningxia Hui Autonomous Region, 1990; LI, 1993; DENG, et al, 1994; Burchfiel, et al, 1995), the study on WQNBFZ is still weak, although some researches have been done by KANG (1990) and TENG, et al (1991). Based on the field investigation and sample dating, the active features about the Fenghuangshan-Tianshui fault (FTF) of WQNBFZ are discussed in the paper.……

关键词： Late Pleistocene