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Influence of nozzle height to width ratio on ignition and NO

Liutao SUN, Yonghong YAN, Rui SUN, Zhengkang PENG, Chunli XING, Jiangquan WU

《能源前沿（英文）》 2021年第15卷第2期页码 431-448 doi: 10.1007/s11708-021-0726-3

摘要： To improve the ignition behavior and to reduce the high NO emissions of blended pulverized fuels (PF) of semicoke (SC), large-scale experiments were conducted in a 300 kW fired furnace at various nozzle settings, i.e., ratios (denoted by / ) of the height of the rectangular burner nozzle to its width of 1.65, 2.32, and 3.22. The combustion tests indicate that the flame stability, ignition performance, and fuel burnout ratio were significantly improved at a nozzle setting of / = 2.32. The smaller / delayed ignition and caused the flame to concentrate excessively on the axis of the furnace, while the larger / easily caused the deflection of the pulverized coal flame, and a high-temperature flame zone emerged close to the furnace wall. NO emissions at the outlet of the primary zone decreased from 447 to 354 mg/m (O = 6%), and the ignition distance decreased from 420 to 246 mm when the / varied from 1.65 to 3.22. Furthermore, the ratio (denoted by / ) of the strong reduction zone area to the combustion reaction zone area was defined experimentally by the CO concentration to evaluate the reduction zone. The / rose monotonously, but its restraining effects on NO formation decreased as / increased. The results suggested that in a test furnace, regulating the nozzle / conditions sharply reduces NO emissions and improves the combustion efficiency of SC blends possessing an appropriate jet rigidity.

关键词： rectangular jet burner nozzle height to width ratio ignition characteristics pyrolyzed semicoke (SC) and bituminous blend NO_x formation

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Piezoelectric diffuser/nozzle micropump with double pump chambers

WANG Wei, ZHANG Ying, TIAN Li, CHEN Xiaojie, LIU Xiaowei

《机械工程前沿（英文）》 2008年第3卷第4期页码 449-453 doi: 10.1007/s11465-008-0076-4

摘要： To eliminate check valve fatigue and valve clogging, diffuser/nozzle elements are used for flow rectification in a valveless diffuser/nozzle micropump instead of valves. However, the application of this type of micropump is restricted because of its pulsating or periodic flow and low pump flux. In this paper, a diffuser/nozzle Si/Glass micropump with two pump chambers by IC and MEMS technology is designed. The fabrication process requires only one mask and one etch step, so that the fabrication has the advantages of low cost, short processing period, and facilitation of miniaturization. The pump is equipped with a glass cover board so as to conveniently observe the flow status. Pump-chambers and diffuser elements are fabricated by the anisotropic KOH-etch technique on the silicone substrate, and the convex corner is designed to compensate for an anisotropic etch. The driving force of the micropump is produced by the PZT piezoelectric actuator. The pump performance with both actuators actuated in anti- or same-phase mode is also researched. The result indicates that the micropump achieves great performance with the actuators working at anti-phase. This may be because the liquid flows steadily, pulse phenomenon is very weak, and the optimal working frequency, pump back pressure, and flow rate are both double that of the pump driven in same-phase.

关键词： diffuser/nozzle Si/Glass phenomenon rectification diffuser/nozzle micropump frequency

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Experimental and CFD analysis of nozzle position of subsonic ejector

Xilai ZHANG, Shiping JIN, Suyi HUANG, Guoqing TIAN

《能源前沿（英文）》 2009年第3卷第2期页码 167-174 doi: 10.1007/s11708-009-0001-5

摘要： The influence of nozzle position on the performance of an ejector was analyzed qualitatively with free jet flow model. Experimental investigations and computational fluid dynamics (CFD) analysis of the nozzle position of the subsonic ejector were also conducted. The results show that there is an optimum nozzle position for the ejector. The ejecting coefficient reaches its maximum when the nozzle is positioned at the optimum and decreases when deviating. Moreover, the nozzle position of an ejector is not a fixed value, but is influenced greatly by the flow parameters. Considering the complexity of the ejector, CFD is reckoned as a useful tool in the design of ejectors.

关键词： ejector nozzle position ejecting coefficient CFD

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Yield-height correlation and QTL localization for plant height in two lowland switchgrass populations

Shiva O. MAKAJU, Yanqi WU, Michael P. ANDERSON, Vijaya G. KAKANI, Michael W. SMITH, Linglong LIU, Hongxu DONG, Dan CHANG

《农业科学与工程前沿（英文）》 2018年第5卷第1期页码 118-128 doi: 10.15302/J-FASE-2018201

摘要： Switchgrass ( L.), as a model herbaceous crop species for bioenergy production, is targeted to improve biomass yield and feedstock quality. Plant height is a major component contributing to biomass yield. Accordingly, the objectives of this research were to analyze phenotypic variation for biomass and plant height and the association between them and to localize associated plant height QTLs. Two lowland switchgrass mapping populations, one selfed and another hybrid population established in the field at Perkins and Stillwater, Oklahoma, were deployed in the experiment for two years post establishment. Large genetic variation existed for plant biomass and height within the two populations. Plant height was positively correlated with biomass yield in the selfed population ( = 0.39, <0.0001) and the hybrid population ( = 0.41, <0.0001). In the selfed population, a joint analysis across all environments revealed 10 QTLs and separate analysis for each environment, collectively revealed 39 QTLs related to plant height. In the hybrid population, the joint analysis across overall environments revealed 35 QTLs and the separate analysis for each environment revealed 38 QTLs. The findings of this research contribute new information about the genetic control for plant height and will be useful for future plant breeding and genetic improvement programs in lowland switchgrass.

关键词： yield-height QTL localization lowland switchgrass

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Depth of cut models for multipass abrasive waterjet cutting of alumina ceramics with nozzle oscillation

Jun WANG

《机械工程前沿（英文）》 2010年第5卷第1期页码 19-32 doi: 10.1007/s11465-009-0082-1

摘要： An experimental study of the depth of cut in multipass abrasive waterjet (AWJ) cutting of alumina ceramics with controlled nozzle oscillation is presented. It is found that this cutting technique can significantly increase the depth of cut by an average of 50.8% as compared to single pass cutting without nozzle oscillation under the corresponding cutting conditions and within the same cutting time. Predictive models for the depth of cut are then developed. The modelling process starts with single pass cutting using a dimensional analysis technique and the particle erosion theories applied to alumina ceramics, before progressing to the development of the models for multipass cutting. The models are finally assessed both qualitatively and quantitatively with experimental data. It is shown that the model predictions are in good agreement with the experimental data with the average deviations of about 1%.

关键词： abrasive waterjet engineering ceramics depth of cut cutting performance nozzle oscillation machining

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Calculation methods of the crack width and deformation for concrete beams with high-strength steel bars

Jianmin ZHOU, Shuo CHEN, Yang CHEN

《结构与土木工程前沿（英文）》 2013年第7卷第3期页码 316-324 doi: 10.1007/s11709-013-0211-0

摘要： Three groups of concrete beams reinforced with high-strength steel bars were tested, and the crack width and deformation of the specimens were observed and studied. To facilitate the predictions, two simplified formulations according to a theory developed by the first author were proposed. The advantages of the formulations were verified by the test data and compared with several formulas in different codes.

关键词： concrete beam high-strength steel bar crack width deformation

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Numerical analysis of rotating stall characteristics in vaneless diffuser with large width-radius ratio

GAO Chuang, GU Chuangang, WANG Tong, DAI Zhengyuan

《能源前沿（英文）》 2008年第2卷第4期页码 457-460 doi: 10.1007/s11708-008-0071-9

摘要： A two-dimensional model, where the influence of wall boundary layers is neglected and inlet jet-wake velocity patterns are prescribed, was applied to simulate one vaneless diffuser with a large width-radius ratio. The impact of diffuser length, impeller blade number, etc. on the rotating stall was analyzed. Computational results show that a different mechanism does exist for diffusers with large width-radius ratios. Comparison with related conclusions and references is supportive of the model.

关键词： Comparison Computational two-dimensional influence different mechanism

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油压极值比与极值比效率

齐茂林

《中国工程科学》 2001年第3卷第4期页码 73-75

摘要：

文章应用基础公式，推导液压系统油压极值比与极值比效率之间的关系式。该式说明，油压极值比越大，极值比效率就越低。提出了油压极值比是可以设计和选择的。

关键词：油压极值比极值比效率液压系统

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基于单位有效疏散宽度使用率的一种疏散设计评价方法

杨健鹏,张和平,潘峥,马宁,蒋为诚

《中国工程科学》 2006年第8卷第5期页码 94-97

摘要：

在建筑物的设计中，疏散通道的设计是非常重要的内容，设计是否合理关系到火灾时建筑物内的人员能否安全及时地疏散。但现行规范中并没有涉及到如何判断不同疏散方案的合理性。提出了一种评价方法，采用疏散通道出口单位有效疏散宽度使用率作为主要的评价指标，能较好地反映出不同设计方案之间的差异，并对如何调整疏散通道的位置使其更有利于人员的安全疏散有一定的指导作用。

关键词：火灾人员疏散单位有效疏散宽度使用率

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Controlling interstory drift ratio profiles via topology optimization strategies

《结构与土木工程前沿（英文）》 2023年第17卷第2期页码 165-178 doi: 10.1007/s11709-022-0892-3

摘要： An approach to control the profiles of interstory drift ratios along the height of building structures via topology optimization is proposed herein. The theoretical foundation of the proposed approach involves solving a min–max optimization problem to suppress the maximum interstory drift ratio among all stories. Two formulations are suggested: one inherits the bound formulation and the other utilizes a p-norm function to aggregate all individual interstory drift ratios. The proposed methodology can shape the interstory drift ratio profiles into inverted triangular or quadratic patterns because it realizes profile control using a group of shape weight coefficients. The proposed formulations are validated via a series of numerical examples. The disparity between the two formulations is clear. The optimization results show the optimal structural features for controlling the interstory drift ratios under different requirements.

关键词： interstory drift ratio aggregation function bound formulation min–max problem topology optimization

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Numerical analysis of nonlinear dynamic behavior of earth dams

Babak EBRAHIMIAN

《结构与土木工程前沿（英文）》 2011年第5卷第1期页码 24-40 doi: 10.1007/s11709-010-0082-6

摘要： A numerical study is conducted to investigate the dynamic behavior of earth dams. The numerical investigation employs a fully nonlinear dynamic finite difference analysis incorporating a simple elastic perfectly plastic constitutive model to describe the stress-strain response of the soil and the Rayleigh damping to increase the level of hysteretic damping. The extended Masing rules are implemented into the constitutive model to explain more accurately the soil response under general cyclic loading. The soil stiffness and hysteretic damping change with loading history. The procedures for calibrating the constructed numerical model with centrifuge test data and also a real case history are explained. For the latter, the Long Valley (LV) earth dam subjected to the 1980 Mammoth Lake earthquake as a real case-history is analyzed and the obtained numerical results are compared with the real measurements at the site in both the time and frequency domains. Relatively good agreement is observed between computed and measured quantities. It seems that the Masing rules combined with a simple elasto-plastic model gives reasonable numerical predictions. Afterwards, a comprehensive parametric study is carried out to identify the effects of dam height, input motion characteristics, soil behavior, strength of the shell materials and dam reservoir condition on the dynamic response of earth dams. Three real earthquake records with different levels and peak acceleration values (PGAs) are used as input motions. The results show that the crest acceleration decreases when the dam height increases and no amplification is observed. Further, more inelastic behavior and more earthquake energy absorption are observed in higher dams.

关键词： earth dam numerical nonlinear response dynamic analysis earthquake dam height

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Insult of gastroesophageal reflux on airway: clinical significance of pharyngeal nozzle

null

《医学前沿（英文）》 2015年第9卷第1期页码 117-122 doi: 10.1007/s11684-014-0343-1

摘要：

At the very time of global paying the highest attention to the worst insults of smoking as well as haze on the airway, everybody knows both are exogenous and noticeable. However, people mostly, including many medical personnel, do not know how badly the gastroesophageal reflux (GER) insults on our own airway. Symptoms of GER are commonly seen as heartburn and regurgitation, which can be mostly tolerated. However, when the up going gastric content reversely passes the esophagus and then the distal pharynx, where it appears a beak like stricture, serving as a nozzle, so as to produce numerous micro-particles and reach the oro-nasal cavity and also the airway causing allergic rhinitis and asthmatic attacks, even pulmonary parenchyma lesions. It will reduce life quality or even jeopardize life. The point that the endogenous insult appears in the respiratory system, but originates from the digestive tract is not well known and often undiagnosed and not correctly treated. The GER induced airway challenge is a treatable and preventive entity, as soon as a diagnosis is made, a good relief could be expected by means of life style adjustment, medicine, or fixation of the patulous cardia through radiofrequency or fundoplication. The author Dr. Zhonggao Wang had suffered it for long and symptoms disappeared for 8 years after anti-reflux surgery. Here is a presentation of Dr. Zhonggao Wang and his team’s work and would call attention to the public so as to recognize this relatively unknown entity — a treatable condition occurring from human itself, but not from outside surroundings as smoking or haze does.

关键词： gastroesophageal reflux airway pharyngeal nozzle micro-aspiration asthma

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A methodology of implementing target mixing ratio for asphalt mixture

Yucheng HUANG, Lun JI, Rui WEN, Ming ZHANG

《结构与土木工程前沿（英文）》 2017年第11卷第3期页码 308-314 doi: 10.1007/s11709-017-0405-y

摘要： In order to implement the objective mix design of hot mix asphalt adequately during the construction process, the significance of objective mixing ratio was elaborated, and the variability of materials and its control method were analyzed. An engineering example is used to illustrate the debugging process of asphalt mixture batching & mixing plant and the dynamic quality management methods. The results show that the set of methods can not only implement the objective mixing ratio of hot mix asphalt adequately, but also control production during the construction process effectively.

关键词： asphalt mixture target mixing ratio mix design implementation batching & mixing plant debugging

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Diagnostic evaluation of plasma aldosterone concentration to plasma renin activity ratio in primary aldosteronism

ZHANG Huilan, WANG Daowen

《医学前沿（英文）》 2008年第2卷第1期页码 11-14 doi: 10.1007/s11684-008-0003-4

摘要： Using the plasma aldosterone concentration to plasma renin activity ratio (PAC/PRA ratio) as the screening test of choice for primary aldosteronism in hypertensive patients, we studied the clinical characteristics and the diagnostic value of PAC/PRA ratio in primary aldosteronism. The plasma aldosterone concentration (PAC) and plasma renin activity (PRA) levels were measured by radioimmunoassay in 902 hypertensive patients from out-patient clinics or hospitals. One hundred and twenty-six suspected primary aldosteronism patients whose PAC/PRA ratio was > 25 ng/dL/ng/mL/hr had a lamellar computed tomography (CT) scan in the adrenal gland and follow-up visits. The proportion of primary aldosteronism in hypertensive patients was 14% (126/902). There were 54 patients with unilateral or bilateral hyperplasia and 25 patients with adenoma according to the CT scan. 39% (49/126) of the patients with primary aldosteronism had hypokalemia. Twenty-five patients received surgical treatment. The efficacy and cure rates were 100% (25/25) and 48% (12/25), respectively. The effective rate of aldactone and the single-drug cure rate were 89% (48/54) and 24% (13/54), respectively. Primary aldosteronism affects over 10% of hypertensive patients in China. The PAC/PRA ratio can be considered as a routine screening test in hypertensives, especially resistant hypertensive patients and a high PAC/PRA ratio is an invaluable index in primary aldosteronism diagnosis.

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甚高频雷达复杂场景中目标高度和多径衰减联合估计 Research Articles

陈胜,赵永波,胡毅立,曹成虎,庞晓娇

《信息与电子工程前沿（英文）》 2022年第23卷第6期页码 937-949 doi: 10.1631/FITEE.2100003

摘要：

由于多径效应的影响，甚高频雷达低角估计是雷达领域难题之一，尤其是在反射条件未知的复杂情况下，低角估计更难解决。针对这一问题，提出一种目标高度和多径衰减联合估计算法。该算法首先利用数据本身的特性估算反射系数幅度，当该幅度估计值很小时，认为没有反射信号，然后将反射系数的相位和直达信号与反射信号之间的相位差当作同一部分，即多径相位衰减，并对其进行搜索。推导了该算法的克拉美罗界。最后，计算机仿真和实测数据处理结果表明，该算法在复杂场景下具有良好估计性能，并且在仅有单次快拍的条件下仍能较好地工作。

关键词：低角估计；甚高频雷达；复杂场景；多径效应；高度估计

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标题作者时间类型操作

Influence of nozzle height to width ratio on ignition and NO

Liutao SUN, Yonghong YAN, Rui SUN, Zhengkang PENG, Chunli XING, Jiangquan WU

期刊论文

Piezoelectric diffuser/nozzle micropump with double pump chambers

WANG Wei, ZHANG Ying, TIAN Li, CHEN Xiaojie, LIU Xiaowei

期刊论文

Experimental and CFD analysis of nozzle position of subsonic ejector

Xilai ZHANG, Shiping JIN, Suyi HUANG, Guoqing TIAN

期刊论文