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Experimental investigation and ANN modeling on improved performance of an innovative method of using heaveresponse of a non-floating object for ocean wave energy conversion

Srinivasan CHANDRASEKARAN, Arunachalam AMARKARTHIK, Karuppan SIVAKUMAR, Dhanasekaran SELVAMUTHUKUMARAN, Shaji SIDNEY

《能源前沿（英文）》 2013年 第7卷 第3期   页码 279-287 doi: 10.1007/s11708-013-0268-4

摘要： To convert wave energy into usable forms of energy by utilizing heaving body, heaving bodies (buoys) which are buoyant in nature and float on the water surface are usually used. The wave exerts excess buoyancy force on the buoy, lifting it during the approach of wave crest while the gravity pulls it down during the wave trough. A hydraulic, direct or mechanical power takeoff is used to convert this up and down motion of the buoy to produce usable forms of energy. Though using a floating buoy for harnessing wave energy is conventional, this device faces many challenges in improving the overall conversion efficiency and survivability in extreme conditions. Up to the present, no studies have been done to harness ocean waves using a non-floating object and to find out the merits and demerits of the system. In the present paper, an innovative heaving body type of wave energy converter with a non-floating object was proposed to harness waves. It was also shown that the conversion efficiency and safety of the proposed device were significantly higher than any other device proposed with floating buoy. To demonstrate the improvements, experiments were conducted with non-floating body for different dimensions and the heave response was noted. Power generation was not considered in the experiment to observe the worst case response of the heaving body. The device was modeled in artificial neural network (ANN), the heave response for various parameters were predicted, and compared with the experimental results. It was found that the ANN model could predict the heave response with an accuracy of 99%.

关键词： ocean wave energy     point absorbers     heaving body     non-floating object     heave response ratio     artificial neural network (ANN)    

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Laboratory experiment on using non-floating body to generate electrical energy from water waves

Arunachalam AMARKARTHIK, Srinivasan CHANDRASEKARAN, Karuppan SIVAKUMAR, Harender SINHMAR

《能源前沿（英文）》 2012年 第6卷 第4期   页码 361-365 doi: 10.1007/s11708-012-0210-1

摘要： This paper describes an innovative method of using a non-buoyant body to harness ocean waves. All the point absorbers are buoyant in nature and move up due to buoyancy and come down because of gravity. The point absorbers are designed to move along the waves to make the device efficient. These devices face excessive stress during the rough weather on account of the extreme motion of waves and cause the total device failure. The present study shows that using a non-buoyant body for conventional point absorber principle is much efficient and safer than any other device proposed till today. A small scale wave energy converter with non-buoyant body was designed, fabricated and tested in small scale wave maker. An electrical generator was coupled with the device to generate electrical energy from harnessed waves. The generator was electrically loaded and the generated power was measured. It was found from the experiments that the proposed device showed a significant improvement in electricity generation and safety during extreme conditions. In addition to the electricity generation, the characteristics of the device were also studied by using various wave and device parameters.

关键词： ocean wave energy     point absorbers     heaving body     non-floating object     heave response ratio     electrical energy generation    

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Thermo-mechanical simulation of frost heave in saturated soils

《结构与土木工程前沿（英文）》   页码 1400-1412 doi: 10.1007/s11709-023-0990-x

摘要： Roads are exposed to various degradation mechanisms during their lifetime. The pavement deterioration caused by the surrounding environment is particularly severe in winter when the humidity and subfreezing temperatures prevail. Frost heave-induced damage is one of the winter-related pavement deterioration. It occurs when the porewater in the soil is exposed to freezing temperatures. The study of frost heave requires conducting a multiphysics analysis, considering the thermal, mechanical, and hydraulic fields. This paper presents the use of a coupled thermo-mechanical approach to simulate frost heave in saturated soils. A function predicting porosity evolution is implemented to couple the thermal and mechanical field analyses. This function indirectly considers the effect of the water seepage inside the soil. Different frost heave scenarios with uniform and non-uniform boundary conditions are considered to demonstrate the capabilities of the method. The results of the simulations indicate that the thermo-mechanical model captures various processes involved in the frost heave phenomenon, such as water fusion, porosity variation, cryogenic suction force generation, and soil expansion. The characteristics and consequences of each process are determined and discussed separately. Furthermore, the results show that non-uniform thermal boundaries and presence of a culvert inside the soil result in uneven ground surface deformations.

关键词： frost heave     multiphysics analysis     thermo-mechanical approach     saturated soils    

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Frost heave and freezing processes of saturated rock with an open crack under different freezing conditions

Zhitao LV, Caichu XIA, Yuesong WANG, Ziliang LIN

《结构与土木工程前沿（英文）》 2020年 第14卷 第4期   页码 947-960 doi: 10.1007/s11709-020-0638-z

摘要： Frost heave experiments on saturated sandstone and tuff with an open crack are conducted under uniform and unidirectional freezing conditions. Frost heave of crack in sandstone with high permeability is more significant under uniform freezing condition than that under unidirectional freezing condition. However, frost heave of crack in tuff with low permeability is more significant under unidirectional freezing condition. To illustrate the reasons for this phenomenon, a numerical model on the freezing processes of saturated rock with an open crack considering the latent heat of pore water and water in crack is proposed and confirmed to be reliable. Numerical results show that a frozen shell that blocks the migration of water in crack to rock develops first in the outer part of the rock before the freezing of water in crack under uniform freezing condition. However, the migration path of water in crack to the unfrozen rock under freezing front exists under unidirectional freezing condition. The freezing process and permeability of rock together determine the migration of water in crack and lead to the different frost heave modes of crack for various permeable rocks under different freezing conditions. The frost heave modes of crack in rock with low or high permeability are similar under uniform freezing condition because water migration is blocked by a frozen shell and is irrelevant to rock permeability. For high permeability rock, the frost heave of crack will be weakened due to water migration under unidirectional freezing condition; however, the frost heave of crack would be more significant for low permeability rock because water migration is blocked under unidirectional freezing condition. Therefore, the freezing condition and rock permeability determine the frost heave of rock with crack together, and this should be concerned in cold regions engineering applications.

关键词： frost heave     rock with crack     freezing process     freezing condition     frost heave mode    

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Seepage failure by heave in sheeted excavation pits constructed in stratified cohesionless soils

Serdar KOLTUK, Jie SONG, Recep IYISAN, Rafig AZZAM

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1415-1431 doi: 10.1007/s11709-019-0565-z

摘要： In this study, experimental and numerical investigations are performed to clarify the seepage failure by heave in sheeted excavation pits in stratified cohesionless soils in which a relatively permeable soil layer ( ) lies above a less permeable soil layer ( ) between excavation base and wall tip. It is shown that the evaluation of base stabilities of excavation pits against seepage failure by using Terzaghi and Peck’s approach leads to considerably lower critical potential differences than those obtained from the model tests. On the other hand, a relatively good agreement is achieved between the results of the model tests and the finite element (FE) analyses. Further investigations are performed by using axisymmetric excavation models with various dimensions and ground conditions, and a comparison between the results obtained from Terzaghi and Peck’s approach and finite element analyses is given.

关键词： seepage failure by heave     cohesionless stratified soil     model test     Terzaghi and Peck’s approach     FE analysis    

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升沉补偿装置虚拟样机协同设计及仿真分析

吕东,何将三,刘少军,黄锴

《中国工程科学》 2004年 第6卷 第3期   页码 36-40

摘要：

采用参数并行集成化方法设计深海采矿升沉补偿装置的虚拟样机，并进行了虚拟试验仿真研究，探讨协同设计在复杂机电系统中的具体应用，为深海开采系统总体设计提供设计理论参考。

关键词： 升沉补偿     虚拟样机     协同设计     仿真    

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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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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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标题 作者 时间 类型 操作

Experimental investigation and ANN modeling on improved performance of an innovative method of using heaveresponse of a non-floating object for ocean wave energy conversion

Srinivasan CHANDRASEKARAN, Arunachalam AMARKARTHIK, Karuppan SIVAKUMAR, Dhanasekaran SELVAMUTHUKUMARAN, Shaji SIDNEY

期刊论文

Laboratory experiment on using non-floating body to generate electrical energy from water waves

Arunachalam AMARKARTHIK, Srinivasan CHANDRASEKARAN, Karuppan SIVAKUMAR, Harender SINHMAR

期刊论文

Thermo-mechanical simulation of frost heave in saturated soils

期刊论文

Frost heave and freezing processes of saturated rock with an open crack under different freezing conditions

Zhitao LV, Caichu XIA, Yuesong WANG, Ziliang LIN

期刊论文

Seepage failure by heave in sheeted excavation pits constructed in stratified cohesionless soils

Serdar KOLTUK, Jie SONG, Recep IYISAN, Rafig AZZAM

期刊论文

升沉补偿装置虚拟样机协同设计及仿真分析

吕东,何将三,刘少军,黄锴

期刊论文

Design and analysis of electrothermal metasurfaces

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

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