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Design and analysis of electrothermal metasurfaces

Xiu LIU, Zhuo LI, Zexiao WANG, Hyeong Seok YUN, Sheng SHEN

《能源前沿（英文）》 2023年 第17卷 第1期   页码 134-140 doi: 10.1007/s11708-022-0841-9

摘要： Electrothermal metasurfaces have garnered considerable attention owing to their ability to dynamically control thermal infrared radiation. Although previous studies were mainly focused on metasurfaces with infinite unit cells, in practice, the finite-size effect can be a critical design factor for developing thermal metasurfaces with fast response and broad temperature uniformity. Here, we study the thermal metasurfaces consisting of gold nanorods with a finite array size, which can achieve a resonance close to that of the infinite case with only several periods. More importantly, such a small footprint due to the finite array size yields response time down to a nanosecond level. Furthermore, the number of the unit cells in the direction perpendicular to the axis of nanorods is found to be insensitive to the resonance and response time; thus, providing a tunable aspect ratio that can boost the temperature uniformity in the sub-Kelvin level.

关键词： modulated thermal infrared radiation     metasurface     nanosecond response time     sub-Kelvin temperature uniformity     finite size     aspect ratio    

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Experimental and parametrical investigation of pre-stressed ultrahigh-performance fiber-reinforced concrete railway sleepers

《结构与土木工程前沿（英文）》 2023年 第17卷 第3期   页码 411-428 doi: 10.1007/s11709-023-0928-3

摘要： In this study, ultrahigh-performance fiber-reinforced concrete (UHPFRC) used in a type B70 concrete sleeper is investigated experimentally and parametrically. The main parameters investigated are the steel fiber volume fractions (0%, 0.5%, 1%, and 1.5%). Under European standards, 35 UHPFRC sleepers are subjected to static bending tests at the center and rail seat sections, and the screw on the fastening system is pulled out. The first cracking load, failure load, failure mode, crack propagation, load–deflection curve, load–crack width, and failure load from these tests are measured and compared with those of a control sleeper manufactured using normal concrete C50. The accuracy of the parametric study is verified experimentally. Subsequently, the results of the study are applied to UHPFRC sleepers with different concrete volumes to investigate the effects of the properties of UHPFRC on their performance. Experimental and parametric study results show that the behavior of UHPFRC sleepers improves significantly when the amount of steel fiber in the mix is increased. Sleepers manufactured using UHPFRC with a steel fiber volume fraction of 1% and a concrete volume less than 25% that of standard sleeper B70 can be used under the same loads and requirements, which contributes positively to the cost and surrounding environment.

关键词： pre-stressed concrete sleeper     ultrahigh performance fiber-reinforced concrete     pull-out test     static bending test     steel fiber     aspect ratio     volume fraction    

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低高宽比矩形微通道中流动沸腾的压降特性

张炳雷,徐进良,肖泽军

《中国工程科学》 2007年 第9卷 第12期   页码 86-93

摘要： 以甲醇为工质，在不同进口温度、质量流率、热流密度和倾角下，对低高宽比矩形微通道中流动沸腾压降特性进行了研究，并分别采用均相模型和分相模型对通道压降进行了计算。通过对比实验结果与计算结果发现，均相模型中两相平均粘度的计算应当采用Dukler公式，用其他计算式时误差较大；利用LockhartMartinelli关系式进行的分相模型计算发现，现有C值计算公式，如Chisholm,Lee and Lee，Mishima及Qu and Mudawar等，都不能用于预测该实验中低高宽比微通道的两相压降。实验发现当通

关键词： 压降特性；均相模型；分相模型；微通道；流动沸腾    

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一种小展弦比高升力飞机的气动布局研究

宋文骢,谢品,郑遂,李玉璞

《中国工程科学》 2001年 第3卷 第8期   页码 70-75

摘要：

针对未来歼击机隐身、高机动和超声速巡航的特点，分析了主要的设计矛盾，并且就亚跨声速升阻特性、低速大迎角特性和超声速阻力特性等若干设计问题提出了具体的解决方案。作者认为，深入研究流动机理，挖掘现有气动力措施的应用潜力，发展新的设计概念，采用相应的总体与控制措施，在众多的设计点之间权衡折衷取舍，有可能全面达到设计目标。

关键词： 气动布局     超声速巡航     隐身     过失速机动    

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Controlled synthesis of uniform silver nanowires with high aspect ratios in aqueous solutions of gemini

XU Jian, LIU Weijun, LIU Honglai, HU Ying

《化学科学与工程前沿（英文）》 2007年 第1卷 第3期   页码 221-227 doi: 10.1007/s11705-007-0040-6

摘要： A simple solution-phase approach has been demonstrated for the large-scale synthesis of silver nanowires with diameters in the range of 15 25 nm, and lengths usually in the range of tens of micrometers. In the presence of gemini surfactant 1,3-bis(cetyldimethylammonium) propane dibromide (16-3-16), the growth of silver could be directed into a highly anisotropic mode to form uniform nanowires with aspect ratios up to about 2,000. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), X-ray powder diffraction (XRD), electron diffraction (ED), and UV-vis absorption spectroscopy, were used to characterize the as-prepared silver nanowires, indicating the formation of a highly pure phase, good crystallinity, as well as a uniform diameter.

关键词： solution-phase     photoelectron spectroscopy     16-3-16     surfactant     transmission    

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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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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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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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Enhancing the efficiency of nitrogen removing bacterial population to a wide range of C:N ratio (1.5:

《环境科学与工程前沿（英文）》 2022年 第16卷 第8期 doi: 10.1007/s11783-022-1522-y

摘要：

• Simultaneous C & N removal in Methammox occurs at wide C:N ratio.

关键词： Methanogens     Biological Nitrogen Removal (BNR)     Simultaneous     Methammox     C:N ratio    

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Experimental study of structural damage identification based on modal parameters and decay ratio of acceleration

Zhigen WU, Guohua LIU, Zihua ZHANG

《结构与土木工程前沿（英文）》 2011年 第5卷 第1期   页码 112-120 doi: 10.1007/s11709-010-0069-3

摘要： A novel damage assessment method based on the decay ratio of acceleration signals (DRAS) was proposed. Two experimental tests were used to show the efficiency. Three beams were gradually damaged, and then the changes of dynamic parameters were monitored from initial to failure state. In addition, a new method was compared with the linear modal-based damage assessment using wavelet transform (WT). The results clearly show that DRAS increases in linear elasticity state and microcrack propagation state, while DRAS decreases in macrocrack propagation state. Preliminary analysis was developed considering the beat phenomenon in the nonlinear state to explain the turn point of DRAS. With better sensibility of damage than modal parameters, probably DRAS is a promising damage indicator in damage assessment.

关键词： damage assessment     decay ratio of acceleration signals (DRAS)     wavelet transform (WT)     modal analysis     reinforced concrete beam     beat phenomenon    

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The influence of the NCO/OH ratio and the 1,6-hexanediol/dimethylol propionic acid molar ratio on the

Jiao Feng, Qiuhao Lu, Weimin Tan, Kequan Chen, Pingkai Ouyang

《化学科学与工程前沿（英文）》 2019年 第13卷 第1期   页码 80-89 doi: 10.1007/s11705-018-1763-2

摘要：

1,5-Pentamethylene diisocyanate, a novel aliphatic diisocyanate formed from bio-based 1,5-pentamethylenediamine, has been used as a hard segmented material to synthesize polyurethane. In this study, several waterborne polyurethane (WPU) dispersions have been successfully prepared by a prepolymer process from 1,5-pentamethylene diisocyanate poly(polyether) with different NCO/OH ratios and 1,6-hexanediol (HDO)/dimethylol propionic acid (DMPA) molar ratios. The Fourier transform infrared (FTIR) spectra, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, and a mechanical tensile test were used to investigate the structures, thermal stability, phase separation, crystallinity, mechanical properties, and adhesive performance of the WPU dispersions. The FTIR results indicate that the degree of hydrogen bonding and the numbers of urea groups increase as the NCO/OH ratio and HDO/DMPA molar ratio increase. Furthermore, the phase separation increases and the thermal stability decreases as the NCO/OH ratio increases or the HDO/DMPA molar ratio decreases. Finally, WPU3.0-2.4 (NCO/OH=3, HDO/DMPA=2.4) exhibits a maximum tensile strength and shear strength, pointing to its possible use as an adhesive. These results could provide a very valuable reference for industrial applications of WPU.

关键词： 1     5-pentamethylene diisocyanate     polyurethane     water based    

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Long term performance of recycled concrete beams with different water–cement ratio and recycled aggregate

Jingwei YING; Feiming SU; Shuangren CHEN

《结构与土木工程前沿（英文）》 2022年 第16卷 第3期   页码 302-315 doi: 10.1007/s11709-022-0803-7

摘要： The purpose of this study is to reveal the service performance of recycled aggregate concrete (RAC) components for different values of water−cement ratio and replacement rate of recycled coarse aggregate (RCA). Generally, the concrete strength decreases with the increase of the replacement rate of RCA, in order to meet the strength requirements when changing the replacement rate of RCA, it is necessary to change the water−cement ratio at the same time. Therefore, the axial compressive strengths of prism with 25 mix proportions, the short-term mechanical properties and long-term deformation properties of reinforced concrete beams were tested respectively by changing water−cement ratio and RCA replacement rate. The bearing capacity and the strain nephogram of samples under different loads were obtained using the Digital Image Correlation (DIC) method, and a self-made gravity loading experimental device was used for long-term deformation investigation. Results showed that the damage pattern of RAC was the same as that of natural aggregate concrete (NAC), but the brittleness was more pronounced. The brittleness of concrete before failure can be reduced more effectively by adjusting the replacement rate of RCA than by adjusting the water−cement ratio. The water−cement ratio has an evident influence on the axial compressive strength and early creep of concrete, while the replacement rate of RCA has a remarkable effect on the long-term deformation of the concrete beams.

关键词： recycled concrete     beam     the replacement rate of recycled coarse aggregate     water–cement ratio     digital image correlation    

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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     NOx formation    

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Improvement of engine performance with high compression ratio based on knock suppression using Miller

Haiqiao WEI, Jie YU, Lei ZHOU

《能源前沿（英文）》 2019年 第13卷 第4期   页码 691-706 doi: 10.1007/s11708-019-0621-3

摘要： In theory, high compression ratio has the potential to improve the thermal efficiency and promote the power output of the SI engine. However, the application of high compression ratio is substantially limited by the knock in practical working process. The objective of this work is to comprehensively investigate the application of high compression ratio on a gasoline engine based on the Miller cycle with boost pressure and split injection. In this work, the specific optimum strategies for CR10 and CR12 were experimentally investigated respectively on a single cylinder DISI engine. It was found that a high level of Miller cycle with a higher boost pressure could be used in CR12 to achieve an effective compression ratio similar to CR10, which could eliminate the knock limits at a high compression ratio and high load. To verify the advantages of the high compression ratio, the fuel economy and power performance of CR10 and CR12 were compared at full and partial loads. The result revealed that, compared with CR10, a similar power performance and a reduced fuel consumption of CR12 at full load could be achieved by using the strong Miller cycle and split injection. At partial load, the conditions of CR12 had very superior fuel economy and power performance compared to those of CR10.

关键词： high compression ratio     knock     Miller cycle     split injection     engine performance    

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标题 作者 时间 类型 操作

Design and analysis of electrothermal metasurfaces

Xiu LIU, Zhuo LI, Zexiao WANG, Hyeong Seok YUN, Sheng SHEN

期刊论文

Experimental and parametrical investigation of pre-stressed ultrahigh-performance fiber-reinforced concrete railway sleepers

期刊论文

低高宽比矩形微通道中流动沸腾的压降特性

张炳雷,徐进良,肖泽军

期刊论文

一种小展弦比高升力飞机的气动布局研究

宋文骢,谢品,郑遂,李玉璞

期刊论文

Controlled synthesis of uniform silver nanowires with high aspect ratios in aqueous solutions of gemini

XU Jian, LIU Weijun, LIU Honglai, HU Ying

期刊论文

油压极值比与极值比效率

齐茂林

期刊论文

Controlling interstory drift ratio profiles via topology optimization strategies

期刊论文

A methodology of implementing target mixing ratio for asphalt mixture

Yucheng HUANG, Lun JI, Rui WEN, Ming ZHANG

期刊论文

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

ZHANG Huilan, WANG Daowen

期刊论文

Enhancing the efficiency of nitrogen removing bacterial population to a wide range of C:N ratio (1.5:

期刊论文

Experimental study of structural damage identification based on modal parameters and decay ratio of acceleration

Zhigen WU, Guohua LIU, Zihua ZHANG

期刊论文

The influence of the NCO/OH ratio and the 1,6-hexanediol/dimethylol propionic acid molar ratio on the

Jiao Feng, Qiuhao Lu, Weimin Tan, Kequan Chen, Pingkai Ouyang

期刊论文

Long term performance of recycled concrete beams with different water–cement ratio and recycled aggregate

Jingwei YING; Feiming SU; Shuangren CHEN

期刊论文

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

Improvement of engine performance with high compression ratio based on knock suppression using Miller

Haiqiao WEI, Jie YU, Lei ZHOU

期刊论文