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Global modeling 2^(nd)-order ionospheric delay and its effects on GNSS precise positioning

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Science China(Physics,Mechanics & Astronomy) 2011年第6期54卷 1059-1067页

作者： ZHANG HongPing lv haixia LI Min SHI Chuang State Key Laboratory of Information Engineering in Surveying Mapping and Remote SensingWuhan UniversityWuhan 430070China GNSS Research Center Wuhan UniversityWuhan 430079China School of Geodesy and Geomatics Wuhan UniversityWuhan 430079China

Ionospheric delay is one of the major error sources in GNSS navigation and ***,the dual-frequency technique is the most widely used in ionospheric refraction ***,dual-frequency measurements can only eliminate the first-order term of ionospheric delay,while the effect of the second-order term on GNSS observations may be several *** this paper,two models,the International Reference Ionosphere (IRI) 2007 and International Geomagnetic Reference Field (IGRF) 11 are used to estimate the second-order term through the integral calculation ***,the simplified single layer ionosphere model in a dipole moment approximation for the earth magnetic field is *** the traditional integral calculation method requires large calculation load and takes much time,it is not convenient for practical ***,although the simplified single layer ionosphere model is simple to implement,it results in larger *** this study,second-order term ionospheric correction formula proposed by Hoque (2007) is improved for estimating the second-order term at a global ***,it is more practicable to estimate the second-order *** importantly,its results have a higher precision of the sub-millimeter level for a global scale in normal *** with Hoque's original regional correction model,which calculates coefficients through polynomial fitting of elevation and latitudes,this study proposes a piece-wise look-up table and interpolation technique to modify Hoque *** utilizing a table file,the modified Hoque model can be conveniently implemented in an engineering software package,like as PANDA in this *** applying the proposed scheme for the second-order ionospheric correction into GNSS precise positioning in both PPP daily and epoch solutions,the results have shown south-shift characteristics in daily solution at a global scale and periodic change with VTEC daily variation in epoch positioning s

关键词： ionospheric delay second-order ionospheric correction GNSS precise positioning

A fast forward computational method for nuclear measurement using volumetric detection constraints

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Nuclear Science and Techniques 2024年第2期35卷 47-63页

作者： Qiong Zhang Lin-lv Lin University of Electronic Science and Technology of China Chengdu 610000China

Owing to the complex lithology of unconventional reservoirs,field interpreters usually need to provide a basis for interpretation using logging simulation *** the various detection tools that use nuclear sources,the detector response can reflect various types of information of the *** Monte Carlo method is one of the primary methods used to obtain nuclear detection responses in complex ***,this requires a computational process with extensive random sampling,consumes considerable resources,and does not provide real-time response ***,a novel fast forward computational method(FFCM)for nuclear measurement that uses volumetric detection constraints to rapidly calculate the detector response in various complex environments is ***,the data library required for the FFCM is built by collecting the detection volume,detector counts,and flux sensitivity functions through a Monte Carlo ***,based on perturbation theory and the Rytov approximation,a model for the detector response is derived using the flux sensitivity function method and a one-group diffusion *** environmental perturbation is constrained to optimize the model according to the tool structure and the impact of the formation and borehole within the effective detection ***,the method is applied to a neutron porosity tool for *** various complex simulation environments,the maximum relative error between the calculated porosity results of Monte Carlo and FFCM was 6.80%,with a rootmean-square error of 0.62 *** field well applications,the formation porosity model obtained using FFCM was in good agreement with the model obtained by interpreters,which demonstrates the validity and accuracy of the proposed method.

关键词： Nuclear measurement Fast forward computation Volumetric constraints

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甲胺生产节能工艺的研究

计算机与应用化学 2009年第6期26卷 811-814页

作者：吕海霞项曙光浙江大学宁波理工学院生物与化学工程分院浙江宁波315100 青岛科技大学炼油化工高新技术研究所山东青岛266042

甲胺是重要的有机化工原料,我国甲胺生产能耗一直远远高于国际水平。为了开发甲胺生产节能流程,全流程模拟某厂甲醇气相胺化法的甲胺工艺,逐个分析系统各个用能设备的能量利用情况,找出节能的关键环节,分3个步骤改进节能,首先在合成系... 详细信息

甲胺是重要的有机化工原料,我国甲胺生产能耗一直远远高于国际水平。为了开发甲胺生产节能流程,全流程模拟某厂甲醇气相胺化法的甲胺工艺,逐个分析系统各个用能设备的能量利用情况,找出节能的关键环节,分3个步骤改进节能,首先在合成系统合理回收能量,提高装置的能量利用效率,能耗下降37%;再模拟优化分离系统5个精馏塔,找到最佳的操作参数,能耗下降20%;最后通过热量集成进一步节能18%。优化后的节能新工艺比原来节能36%,中压蒸汽、高压蒸汽、循环水消耗量降幅分别达50%、22%、40%,节省操作费用464万元/a,只增加少量设备投资,节能效果和经济效益显著。甲胺产品质量较优化前有提高。新的节能工艺为甲醇新装置的设计和原有装置的改造提供有益的参考。

关键词：甲胺节能流程模拟分析

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乡村振兴中的投融资困境及突破方向

理论学刊 2022年第5期 104-111页

作者：张志元吕海霞山东财经大学产业发展研究院山东济南250014 山东财经大学计算机科学与技术学院山东济南250014

实施乡村振兴战略离不开生产要素的投入,尤其是持续大量的资金投入,这就需要建立一个覆盖面广、专业化、多层次的乡村振兴投融资体系。改革开放40多年来,我国在农村发展与农业农村现代化等领域均取得了重大成就,农业农村投融资发挥了重... 详细信息

实施乡村振兴战略离不开生产要素的投入,尤其是持续大量的资金投入,这就需要建立一个覆盖面广、专业化、多层次的乡村振兴投融资体系。改革开放40多年来,我国在农村发展与农业农村现代化等领域均取得了重大成就,农业农村投融资发挥了重要作用。但目前我国乡村振兴投融资仍然面临着投融资需求与供给不协调、财政资金和社会资本对金融资源的撬动作用不足、与乡村振兴投融资相适应的机制不够完善、乡村振兴领域的投融资服务有待加强、投融资担保体系不够健全等困境。为了充分发挥投融资在乡村振兴战略中的作用,需要进一步完善乡村振兴投融资的金融支持体系,健全与乡村振兴投融资相适应的保障机制,充分发挥金融机构在投融资中的重要作用,引导社会资本积极参与乡村振兴。

关键词：乡村振兴战略投融资突破方向

Fractures interaction and propagation mechanism of multi-cluster fracturing on laminated shale oil reservoir

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Petroleum Science 2024年第4期21卷 2600-2613页

作者： Jia-Xin lv Bing Hou Key Laboratory of Petroleum Engineering Ministry of Education China University of Petroleum (Beijing) State Key Laboratory of Petroleum Resources and Engineering China University of Petroleum (Beijing) Department of Petroleum Engineering China University of Petroleum (Beijing) at Karamay

The continental shale reservoirs of Jurassic Lianggaoshan Formation in Sichuan Basin contain thin lamina, which is characterized by strong plasticity and developed longitudinal shell limestone *** improve the production efficiency of reservoirs by multi-cluster fracturing, it is necessary to consider the unbalanced propagation of hydraulic fractures and the penetration effect of fractures. This paper constructed a numerical model of multi-fracture propagation and penetration based on the finite element coupling cohesive zone method; considering the construction cluster spacing, pump rate,lamina strength and other parameters studied the influencing factors of multi-cluster fracture interaction propagation; combined with AE energy data and fracture mode reconstruction method, quantitatively characterized the comprehensive impact of the strength of thin interlayer rock interfaces on the initiation and propagation of fractures that penetrate layers, and accurately predicted the propagation pattern of hydraulic fractures through laminated shale oil reservoirs. Simulation results revealed that in the process of multi-cluster fracturing, the proportion of shear damage is low, and mainly occurs in bedding fractures activated by outer fractures. Reducing the cluster spacing enhances the fracture system's penetration ability, though it lowers the activation efficiency of lamina. The high plasticity of the limestone interlayer may impact the vertical propagation distance of the main fracture. Improving the interface strength is beneficial to the reconstruction of the fracture height, but the interface communication effect is limited. Reasonable selection of layers with moderate lamina strength for fracturing stimulation, increasing the pump rate during fracturing and setting the cluster spacing reasonably are beneficial to improve the effect of reservoir stimulation.

关键词： Laminated shale Multi-cluster fracturing Cross-layer Cohesive zone model Acoustic emission technique

Control of chiral-optical activities by magnetic field based on the transformation of achiral binary crystals into chiral ternary crystals

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Science China Chemistry 2024年第7期67卷 2300-2305页

作者： Zhiyan Chen Yan lv Wei Qin College of Physics Qingdao UniversityQingdao 266071China School of Physics State Key Laboratory of Crystal MaterialsShandong UniversityJinan 250100China Shandong Linuo Photovoltaic Hi-Tech Co. Ltd.Jinan 250100China

Multicomponent self-assembled chiral systems have attracted great attention due to their promising application in the area of spin-photonics and *** this work,through introducing an achiral third component into an achiral binary crystal,a chiral organic ternary crystal is fabricated,where both pronounced chiral-optical coupling and magnetic field dependence of chiral-optical activities are *** transformation of achiral structure into chiral structure generates a significant effect on the polarized state of light and the electron spin resonance ***,the coupling between circularly polarized photon and spin is observed in chiral ternary crystal with pronounced chiral orbit,where obvious magnetic field-transmissivity loop is ***,temperature could increase the magnitude of lattice parameters to lead to a larger helix radius to increase the chiral orbit ***,this work indicates that the further exploration of photon-chiral orbit-spin interactions in organic chiral ternary crystals is promising.

关键词： organic chiral ternary crystals chiral orbit chiral-optical activities magnetic field

Event-triggered sliding mode control of linear repetitive processes and its application in metal rolling process

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Science China(Information Sciences) 2024年第3期67卷 167-181页

作者： Xinyu lv Yugang NIU James LAM Key Laboratory of Smart Manufacturing in Energy Chemical Process (East China University of Science and Technology) Ministry of Education Department of Mechanical Engineering The University of Hong Kong

This paper investigates the design problem of a sliding mode controller for linear repetitive processes(LRPs) with a finite pass length on each pass. Under limited communication resources, an eventtriggered mechanism is implemented from the sensors to the controller, whose triggered sequence is consistent with the evolution direction of LRPs. To periodically orchestrate communication between the controller and actuator, a round-robin scheduling mechanism is established based on the pass length. A sliding function involving the state and pass profile is constructed, and the sliding mode controller is designed using triggered states and pass profile signals. Feasible controller gains are attained to ensure the stability of the resultant closed-loop system. Finally, the proposed strategy is implemented for a multi-roll metal rolling process.

关键词： event-triggered mechanism linear repetitive processes metal rolling process round-robin scheduling sliding mode control

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Numerical Study on Local Flow and Heat Transfer Characteristics of Supercritical CO_(2) in PCHE with Sinusoidal Channels

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Journal of Thermal Science 2024年第1期33卷 41-55页

作者： WENZhexi lv Yigao LI Qing WU Jinglin School of Energy Science and Engineering Central South UniversityChangsha 410083China

Local heat transfer and flow characteristics,which is crucial to the overall performance of supercritical CO_(2) recuperators,is rarely examined in details in reported *** this paper,the local heat transfer and flow characteristics of supercritical CO_(2) in sinusoidal channel printed circuit heat exchangers are numerically investigated under the working conditions of *** on the simplified physical model constituted by10 pitches,the variations of Re,heat flux,Nu,secondary flow and other relevant parameters along the flow direction are analyzed *** is further made between the high and low temperature recuperators(HTR and LTR).It's observed that the local heat transfer and flow characteristics vary greatly from the inlet to the outlet,especially in the *** of 127.5% and 61.7% can be observed on the cold side of the LTR for Re and heat transfer coefficient h, *** indicate that the temperature difference and heat transfer coefficient h should not be regarded as constant and the distribution of h should be carefully considered in the design of the *** complicated interactions among the varying thermophysical properties,buoyancy and the periodically changed centrifugal force are believed to be the key that shapes the flow ***,the changes of the wavy angle θ are found to have greater influence than the changes of mass flow rate in reshaping the flow field when θ>25°.Though gravity direction strongly affects the local heat transfer and flow characteristics,it's also found that the effects on the overall thermal-hydraulic performance are relatively *** the installation direction that yields a_y=g should better be avoided for the sinusoidal channel printed circuit heat exchanger.

关键词： printed circuit heat exchanger supercritical CO_(2) sinusoidal channel heat transfer recuperator

A Generalized MSST Algorithm for Counting Points of Elliptic Curves over F_(p)^(n)

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Journal of Systems Science & Complexity 2024年第4期37卷 1738-1754页

作者： LI Xiao lv Chang PAN Zhizhong Key Laboratory of Cyberspace Security Defense Institute of Information EngineeringChinese Academy of SciencesBeijing 100085China School of Cyber Security University of Chinese Academy of SciencesBeijing 100085China Huawei Technologies Co. Ltd.Shenzhen 518129China

Elliptic curve cryptography is an important part of nowaday's public key *** points of elliptic curves over finite fields is of great significance to the selection of safety *** present,there are many p-adic algorithms,such as SST algorithm,generalized AGM algorithm,Kedlaya algorithm,etc.,which can deal with the situation of finite fields of small *** this paper,the authors generalize the MSST algorithm of characteristic 2 to general fields of odd characteristic,and propose the generalized MSST *** generalized MSST algorithm is achieved by combining the advantages of the SST algorithm and the generalized AGM *** the time complexity of the multiplication of two n-bit numbers is denoted as O((n)^(μ)),then the time complexity of the generalized MSST algorithm is O(n^(2μ+1/1+μ)),which is the same as the improved SST *** practical experiments,the running time of the generalized MSST algorithm is less than that of the improved SST algorithm.

关键词： Elliptic curve generalized AGM algorithm generalized MSST algorithm SST algorithm