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Research in Astronomy and Astrophysics 2013年第8期13卷 991-1012页

作者： zhuo-xi huo Jian-Feng Zhou Department of Engineering Physics and Center for Astrophysics Tsinghua University Key Laboratory of Particle & Radiation Imaging (Tsinghua University) Ministry of Education Key Laboratory of High Energy Radiation Imaging Fundamental Science for National Defense

The hard X-ray modulation telescope （HXMT） mission is mainly devoted to performing an all-sky survey at 1- 250 keV with both high sensitivity and high spatial resolution. The observed data reduction as well as the image reconstruction for HXMT can be achieved by using the direct demodulation method （DDM）. However the original DDM is too computationally expensive for multi-dimensional data with high resolution to be employed for HXMT data. We propose an accelerated direct demodulation method especially adapted for data from HXMT. Simulations are also presented to demonstrate this method.

关键词： methods data analysis methods numerical techniques image processing instrumentation high angular resolution

Point source detection performance of Hard X-ray Modulation Telescope imaging observation

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Research in Astronomy and Astrophysics 2015年第11期15卷 1905-1916页

作者： zhuo-xi huo Yi-Ming Li xiao-Bo Li Jian-Feng Zhou Department of Physics Tsinghua University Centre for Astrophysics Tsinghua University Laboratoire de l'Accélérateur Linéaire Institute of High Energy Physics Chinese Academy of Sciences Department of Engineering Physics Tsinghua University

The Hard X-ray Modulation Telescope（HXMT） will perform an all-sky survey in the hard X-ray band as well as deep imaging of a series of small sky *** expect various compact objects to be detected in these imaging observations. Point source detection performance of HXMT imaging observation depends not only on the instrument but also on the data analysis method that is applied since images are reconstructed from HXMT observed data with numerical methods. The denoising technique used plays an important part in the HXMT imaging data analysis pipeline along with demodulation and source detection. In this paper we have implemented several methods for denoising HXMT data and evaluated the point source detection performances in terms of sensitivities and location accuracies. The results show that direct demodulation with 1-fold cross-correlation should be the default reconstruction and regularization method, although both sensitivity and location accuracy could be further improved by selecting and tuning numerical methods in data analysis used for HXMT imaging observations.

关键词： regularization reconstructed selecting demodulation pixel wavelet pipeline neighborhood tuning histogram

Application of a Space-based Optical Interferometer Toward Measuring Cosmological Distances of Quasars

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Research in Astronomy and Astrophysics 2022年第3期22卷 100-114页

作者： Ying-Ke Huang Yue-Dong Fang Kai-xing Lu Zhi-xiang Zhang Ji-Lin Liu Sha-sha Li Bao-Rui Luo Qin Lin zhuo-xi huo Qian Xuesen Laboratory of Space Technology China Academy of Space TechnologyBeijing 100081China Yunnan Observatories Chinese Academy of SciencesKunming 650011China Department of Astronomy Xiamen UniversityXiamenFujian 361005China

Measuring quasar distance through joint analysis of spectroastrometry and reverberation mapping observations is a new method for driving the development of *** this paper,we carry out detailed simulation and analysis to study the effect of four basic observational parameters(baseline length,exposure time,equivalent diameter and spectral resolution)on the data quality of differential phase curves(DPCs),and furthermore on the accuracy of distance *** our simulation,we adopt an axisymmetrical disk model of a broad line region(BLR)to generate differential phase *** find that the differential phases and their Poisson errors could be amplified by extending the baseline,while the influence of optical path difference errors can be reduced during fitting the BLR *** exposure time or larger equivalent diameter helps reduce the absolute Poisson ***,the relative error of DPCs could be reduced by increasing any of the above three parameters,then the accuracy of distance measurement could be *** contrast,the uncertainty of absolute angular distances(D_(A))could be improved with higher spectral resolution,although the relative error of DPCs would be *** show how the uncertainty of distance measurement varies with the relative error of *** our specific set of model parameters,without considering more complicated structures and kinematics of BLRs in our simulation,it is found that the relative error of DPCs<20%is a limit for accurate distance *** relative error of DPCs has a lower limit(roughly 5%)and the uncertainty in distance measurement can be better than 2%.

关键词： (galaxies:)quasars:emission lines techniques:interferometric (cosmology:)distance scale

Effects of wing flexibility on aerodynamic performance of an aircraft model

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Chinese Journal of Aeronautics 2021年第9期34卷 133-142页

作者： Qinfeng GUO xi HE zhuo WANG Jinjun WANG Key Laboratory of Fluid Mechanics Ministry of EducationBeihang UniversityBeijing 100083China

The low-speed wind tunnel experiment is carried out on a simplified aircraft model to explore the influence of wing flexibility on the aircraft aerodynamic *** investigation involves the measurements of force,membrane deformation and velocity field at Reynolds number of 5.4×10^(4)-1.1×10^(5).In the lift curves,two peaks are *** first peak,corresponding to the stall,is sensitive to the wing flexibility much more than the second peak,which nearly keeps *** the optimal case,in comparison with the rigid wing model,the delayed stall of nearly5°is achieved,and the relative lift increment is about 90%.It is revealed that the lift enhanced region corresponds to the larger deformation and stronger vibration,which leads to stronger flow mixing near the flexible wing ***,the leading-edge separation is suppressed,and the aerodynamic performance is improved ***,the effects of sweep angle and Reynolds number on the aerodynamic characteristics of flexible wing are also presented.

关键词： Aerodynamic forces Flexible wings Flow field Fluid structure interaction Wing tunnel tests

Enhancement of the second harmonic generation from monolayer WS_(2) coupled with a silica microsphere

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Chinese Physics B 2022年第10期31卷 417-422页

作者： xiao-zhuo Qi xi-Feng Ren CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China CAS Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China

Monolayer transition metal dichalcogenides(TMDs) are widely used for integrated optical and photoelectric *** to their broken inversion symmetry, monolayer TMDs have a large second-order optical nonlinearity. However, the optical second-order nonlinear conversion efficiency of monolayer TMDs is still limited by the interaction length. In this work, we theoretically study the second harmonic generation(SHG) from monolayer tungsten sulfide(WS2) enhanced by a silica microsphere cavity. By tuning the position, size, and crystal orientation of the material, second-order nonlinear coupling can occur between the fundamental pump mode and different second harmonic cavity modes, and we obtain an optimal SHG conversion efficiency with orders of magnitude enhancement. Our work demonstrates that the microsphere cavity can significantly enhance SHG from monolayer 2D materials under flexible conditions.

关键词： integrated optics frequency conversion

Colloid-facilitated release of polybrominated diphenyl ethers at an e-waste recycling site: evidence from undisturbed soil core leaching experiments

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Frontiers of Environmental Science & Engineering 2024年第2期18卷 91-101页

作者： Zebin huo Mengjun xi Lianrui Xu Chuanjia Jiang Wei Chen College of Environmental Science and Engineering Ministry of Education Key Laboratory of Pollution Processes and Environmental CriteriaTianjin Key Laboratory of Environmental Remediation and Pollution ControlNankai UniversityTianjin 300350China

Polybrominated diphenyl ethers (PBDEs), a class of persistent organic pollutants, have been frequently detected in soil at e-waste recycling sites. However, the key factors controlling the transport of PBDEs from surface soil to the vadose zone and groundwater are unclear. Here, colloid-enhanced leaching of PBDEs from undisturbed soil cores collected at an e-waste recycling site in Tianjin, China, is reported. Spatially heterogeneous release of colloids and PBDEs was observed in all the tested soil cores under chemical and hydrodynamic perturbations, indicating the presence of preferential flow paths. Colloid concentration in the effluent significantly increased as ionic strength decreased (from 10 to 0.01 mmol/L), probably due to the stronger electrostatic repulsion between colloidal particles and the soil matrix at lower ionic strength. In contrast, colloid mobilization was not significantly affected by the changes in pH of the influent (from 4.0 to 10.0) and flow rate (from a Darcy velocity of 1.5 to 6.0 cm/h). The concentrations of 2,2′,3,3′,4,4′,5,5′,6,6′-decabromodiphenyl ether (BDE-209), the predominant PBDE congener at the site, detected in the leachate (ranging from 1.09 to 3.43 ng/L) were much lower than previously reported results from packed column leaching tests, and were positively correlated with colloid concentrations. This indicates that remobilization of colloids at e-waste recycling sites can promote the leaching and downward migration of PBDEs from surface soil. The findings highlight the potential risk of surface soil PBDE contamination to groundwater quality and call for further understanding of colloid-facilitated transport for predicting the fate of PBDEs at e-waste recycling sites.

关键词： Polybrominated diphenyl ether Colloid-facilitated transport E-waste recycling site Undisturbed soil core Groundwater quality

Asset specificity and farmers' intergenerational succession willingness of apple management

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Journal of Integrative Agriculture 2023年第8期22卷 2553-2566页

作者： ZHANG Qiang-qiang GAO xi-xi Nazir Muhammad ABDULLAHI WANG Yue huo Xue-xi China Center for Agricultural Policy School of Advanced Agricultural SciencesPeking UniversityBejing 100871P.R.China College of Economics and Management Northwest A&F UniversityYangling 712100P.R.China

Understanding the factors behind apple farmers’willingness to pass on the management of their farms to their descendants is crucial to the continuity of apple *** to the high specificity of the human capital,physical assets,land assets,and geographical location in apple production,this study used a binary logistic regression and a mediating effect model to explore the impact of asset specificity on farmers’intergenerational succession willingness of apple management(FISWAM)and to examine the mediating effects of loss aversion in the impact of asset specificity on the *** results showed that about 18.68%of the respondents expressed willingness to transfer their apple business between generations,and the FISWAM was generally *** addition to the negative impact of geographical location specificity(GLS),human capital specificity(HCS),physical assets specificity(PAS),and land assets specificity(LAS)can enhance the *** aversion plays a partial mediating role in the impact of PAS,LAS,and GLS on the FISWAM.

关键词： asset specificity loss aversion apple management intergenerational succession willingness mediating effects examination

Hierarchical Controller Synthesis Under Linear Temporal Logic Specifications Using Dynamic Quantization

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IEEE/CAA Journal of Automatica Sinica 2024年第10期11卷 2082-2098页

作者： Wei Ren zhuo-Rui Pan Weiguo xia xi-Ming Sun the Key Laboratory of Intelligent Control and Optimization for Industrial Equipment of Ministry of Education Dalian University of Technology the School of Control Science and Engineering Dalian University of TechnologyDalian 116024China

Linear temporal logic(LTL)is an intuitive and expressive language to specify complex control tasks,and how to design an efficient control strategy for LTL specification is still a *** this paper,we implement the dynamic quantization technique to propose a novel hierarchical control strategy for nonlinear control systems under LTL *** on the regions of interest involved in the LTL formula,an accepting path is derived first to provide a high-level solution for the controller synthesis ***,we develop a dynamic quantization based approach to verify the realization of the accepting *** realization verification results in the necessity of the controller design and a sequence of quantization regions for the controller ***,the techniques of dynamic quantization and abstraction-based control are combined together to establish the local-to-global control *** abstraction construction and controller design are local and dynamic,thereby resulting in the potential reduction of the computational *** each quantization region can be considered locally and individually,the proposed hierarchical mechanism is more efficient and can solve much larger problems than many existing ***,the proposed control strategy is illustrated via two examples from the path planning and tracking problems of mobile robots.

关键词： Abstraction-based control design dynamic quantization formal methods linear temporal logic(LTL)

Biosorption of Cd2＋ and CU2＋ on immobilized Saccharomyces cerevisiae

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Frontiers of Environmental Science & Engineering 2012年第1期6卷 51-58页

作者： Fengyu ZAN Shouliang huo Beidou xi xiulan ZHAO College of Environmental Science Anhui Normal UniversityWuhu 241000China Chinese Research Academy of Environmental Sciences Beijing 100012China College of Resource and Environment Southwest UniversityChongqing 400716China

The biosorption of Cd2＋ and CH2＋ onto the immobilized Saccharomyces cerevisiae （S. cerevisiae） was investigated in this study. Adsorption kinetics, isotherms and the effect ofpH were studied. The results indicated that the biosorption of Cd^2＋ and Cu^2＋ on the immobilized S. cerevisiae was fast at initial stage and then became slow. The maximum biosorption of heavy metal ions on immobilized S. cerevisiae were observed at pH 4 for Cde＋ and Cu^2＋. by the pseudo-second-order model described the sorption kinetic data well according to the high correlation coefficient （R2） obtained. The biosorption isotherm was fitted well by the Langmuir model, indicating possible mono-layer biosorption of Cd^2＋ and Cu^2＋ on the immobilized S. cerevisiae. Moreover, the immobilized S. cerevisiae after the sorption of Cd^2＋ and Cu^2＋ could be regenerated and reused.

关键词： Saccharomyces cerevisiae (S. cerevisiae) biosorption heavy metals immobilization desorption

Pressure relief of underground ammunition storage under missile accidental ignition

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Defence Technology（防务技术） 2021年第3期17卷 1081-1093页

作者： Ya-wei Wang Yu-zhuo Yang Gao-wan Zou Hui Dong Yan huo College of Aerospace and Civil Engineering Harbin Engineering UniversityHarbinHeilongjiangChina Architecture and Civil Engineering Department City University of Hong KongHong KongChina

Safety of underground ammunition storage is an important issue,especially during the accidental ignition of *** work investigates the pressure and temperature distribution of the multi-layer underground ammunition storage with a pressure relief duct during the accidental ignition process of the missile.A large-scale experiment was carried out using a multi-layered restricted space with a pressure relief duct to simulate the underground ammunition store and a solid rocket motor to simulate the accidental ignition of the *** results show that when the motor gas mass flow increased by5.6 times,the maximum pressure of the ammunition storage increased by 5.87 *** a certain motor flow rate,when the pressure relief exhaust area at the end of the relief duct was reduced by 1/2,the maximum pressure on the first layer did not *** the rate of pressure relief was reduced and the time delayed for the pressure of ammunition store to drop to *** this experiment,when the motor ignition position was located in to the third layer ammunition chamber,the maximum pressure was reduced by 32.9%and also reduced the rate of change of *** addition,for the experimental conditions,the theoretical analysis of the pressure relief of the ammunition storage is given by a simplified *** on the findings,some suggestions to the safety protection design of ammunition store are proposed.

关键词： Underground ammunition storage Pressure relief Large-scale experiment Missile accidental ignition