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梯形渠道梯形喉口量水槽水力特性初探 被引量:1
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作者 冉聃颉 王文娥 胡笑涛 《西北农林科技大学学报(自然科学版)》 CSCD 北大核心 2018年第1期146-154,共9页
【目的】设计一种体型简单、过流能力强的梯形渠道梯形喉口量水槽,为提高小流量时的测流精度和减小大流量时的水头损失提供支持。【方法】对梯形渠道4种喉口收缩比ε(0.427,0.506,0.557,0.681)的梯形喉口量水槽,分别在12种流量(15.39L/s... 【目的】设计一种体型简单、过流能力强的梯形渠道梯形喉口量水槽,为提高小流量时的测流精度和减小大流量时的水头损失提供支持。【方法】对梯形渠道4种喉口收缩比ε(0.427,0.506,0.557,0.681)的梯形喉口量水槽,分别在12种流量(15.39L/s,19.44L/s,23.62L/s,29.39L/s,35.91L/s,39.15L/s,45.00L/s,49.59L/s,54.28L/s,61.15L/s,65.70L/s,71.96L/s)工况下的测流精度、水头损失、临界淹没度、适宜喉口收缩比等水力性能进行试验研究,通过观测15个控制断面的水深分析水面线的变化规律及流量与收缩比、上游水深的关系,并对自由出流条件下的流量公式进行拟合。【结果】梯形喉口量水槽的上游水深与流量间存在良好的指数关系,相关系数高达0.998 6;设计梯形喉口的量水槽有效改善了梯形渠道测流的测流误差和水头损失,喉口收缩比为0.427~0.557时,实测流量与计算流量的最大相对误差为4.643%;喉口收缩比为0.506~0.681时,水头损失最大为上游总水头的12%左右,较长喉道水头损失有所减小;梯形喉口量水槽具有较高的临界淹没度,临界淹没度变化范围为0.85~0.93;综合考虑水头损失及测流精度,较适宜的喉口收缩比为0.506~0.557,喉口倾角为70°~78°。【结论】梯形喉口量水槽为灌区梯形渠道量水槽的设计提供新思路。 展开更多
关键词 梯形渠道 梯形喉口 喉口收缩比 公式 量水精度 头损失
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加强测水量水建设 提高灌区科学管理水平
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作者 苏畔河 《山西水利》 2009年第3期37-38,共2页
测流量水是灌区科学管理、合理调度灌溉水源的重要措施,是实行计划用水的必要手段,介绍了尊村灌区在测量方面的主要做法,即培养建立测流队伍,提高人员业务素质,建立健全规章制度,学习应用高新技术,推广应用技术成果等,经过采取一系列措... 测流量水是灌区科学管理、合理调度灌溉水源的重要措施,是实行计划用水的必要手段,介绍了尊村灌区在测量方面的主要做法,即培养建立测流队伍,提高人员业务素质,建立健全规章制度,学习应用高新技术,推广应用技术成果等,经过采取一系列措施,取得了显著的成绩。 展开更多
关键词 测流技术 业务培训 量水精度 先进设备 尊村灌区
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闸前短管量水设备研究与率定
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作者 韩江 刘云霞 《内蒙古水利》 2001年第4期16-18,共3页
关键词 闸前短管 率定 原理 性能 短管 永济试区 率定成果 量水精度误差分析
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High Accuracy Calculation for Excited-State Energies of H Atoms in a Magnetic Field 被引量:3
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作者 ZHAO Li-Bo DU Meng-Li 《Communications in Theoretical Physics》 SCIE CAS CSCD 2009年第8期339-345,共7页
Using the recently developed finite-basis-set method with B splines, excited states of H atoms in a magnetic field have been calculated. Energy levels are presented for the ten excited states, 2so, 3d'0, 3po, 3p-1, 3... Using the recently developed finite-basis-set method with B splines, excited states of H atoms in a magnetic field have been calculated. Energy levels are presented for the ten excited states, 2so, 3d'0, 3po, 3p-1, 3d_1, 4d-1, 3d-2, 4d-2, 4f-2 , and 5f-2 as a function of magnetic field strengths with a range from zero up to 2.35 × 10^6 T. The obtained results are compared with available high accuracy theoretical data reported in the literature and found to be in excellent agreement. The comparison also shows that the current method can produce energy levels with an accuracy higher than the existing high accuracy method [Phys. Rev. A 54 (1996) 287]. Here high accuracy energy levels are for the first time reported for the 3d'0, 4d-1, 4d-2, 4f-2, and 5f-2 states. 展开更多
关键词 H atoms strong magnetic fields white dwarf stars
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Diagnostic and therapeutic implications of the association between ferritin level and severity of nonalcoholic fatty liver disease 被引量:15
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作者 Luca Valenti Paola Dongiovanni Silvia Fargion 《World Journal of Gastroenterology》 SCIE CAS CSCD 2012年第29期3782-3786,共5页
Nonalcoholic fatty liver disease(NAFLD),defined by excessive liver fat deposition related to the metabolic syndrome,is a leading cause of progressive liver disease,for which accurate non-invasive staging systems and e... Nonalcoholic fatty liver disease(NAFLD),defined by excessive liver fat deposition related to the metabolic syndrome,is a leading cause of progressive liver disease,for which accurate non-invasive staging systems and effective treatments are still lacking.Evidence has shown that increased ferritin levels are associated with the metabolic insulin resistance syndrome,and higher hepatic iron and fat content.Hyperferritinemia and iron stores have been associated with the severity of liver damage in NAFLD,and iron depletion reduced insulin resistance and liver enzymes.Recently,Kowdley et al demonstrated in a multicenter study in 628 adult patients with NAFLD from the NAFLD-clinical research network database with central re-evaluation of liver histology and iron staining that the increased serum ferritin level is an independent predictor of liver damage in patients with NAFLD,and is useful to identify NAFLD patients at risk of non-alcoholic steatohepatitis and advanced fibrosis.These data indicate that incorporation of serum ferritin level may improve the performance of noninvasive scoring of liver damage in patients with NAFLD,and that iron depletion still represents an attractive therapeutic target to prevent the progression of liver damage in these patients. 展开更多
关键词 Fibrosis Ferritin Iron overload Nonalcoholic fatty liver disease Steatohepatitis Steatosis
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Circular Rydberg States of Atomic Hydrogen in an Arbitrary Magnetic Field
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作者 赵力波 B.C.Saha 杜孟利 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第9期481-486,共6页
We report a theoretical scheme using a B-spline basis set to improve the poor computational accuracy of circular Rydberg states of hydrogen atoms in the intermediate magnetic field. This scheme can produce high accura... We report a theoretical scheme using a B-spline basis set to improve the poor computational accuracy of circular Rydberg states of hydrogen atoms in the intermediate magnetic field. This scheme can produce high accuracy energy levels and valid for an arbitrary magnetic field. Energy levels of hydrogen are presented for circular Rydberg states with azimuthal quantum numbers |m| =10-70 as a function of magnetic field strengths ranging from zero to 2.35 × 10^9 T. The variation of spatial distributions of electron probability densities with magnetic field strengths is discussed and competition between Coulomb and magnetic interactions is illustrated. 展开更多
关键词 hydrogen atom circular Rydberg state magnetic field B-spline basis
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Magnetometer calibration algorithm based on ellipsoid constraint
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作者 董明杰 Chou Wusheng Fang Bin 《High Technology Letters》 EI CAS 2015年第4期407-413,共7页
Calibration of magnetometer is an essential part to obtain high measurement precision.However,the existing calibration methods are basically the calibration of all attitudes,which means tough work when the magnetomete... Calibration of magnetometer is an essential part to obtain high measurement precision.However,the existing calibration methods are basically the calibration of all attitudes,which means tough work when the magnetometer is applied in strapdown inertial navigation system(SINS).So a quick,easy and effective calibration algorithm is developed based on the ellipsoid constraint to calibrate magnetometers.In this paper,the measuring principle and error characteristic of the magnetometer are analysed to study its magnetic interference.During the process,a magnetometer calibration model is set up to convert the calibration to ellipsoid fitting based on the characteristic of hard magnetic interference and soft magnetic interference.Then the algorithm is tested by mimic experiment.The result shows that measurement precision is improved after the calibration,and then the magnetometer is installed in a control cabin of an underwater robot which is designed and developed by us,and actual magnetometer calibration experiments are conducted to further verify the validity of the algorithm. 展开更多
关键词 calibration MAGNETOMETER ellipsoid constraint strapdown inertial navigation sys-tem (SINS)
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