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Effect of sodium bicarbonate solution on methyltrimethoxysilane-derived silica aerogels dried at ambientpressure

Yujing Liu, Xiao Han, Balati Kuerbanjiang, Vlado K. Lazarov, Lidija Šiller

《化学科学与工程前沿（英文）》 2021年 第15卷 第4期   页码 954-959 doi: 10.1007/s11705-020-2028-4

摘要： Here we present an economical ambient pressure drying method of preparing monolithic silica aerogels from methyltrimethoxysilane precursor while using sodium bicarbonate solution as the exchanging solvent. We prepared silica aerogels with a density and a specific surface area of 0.053 g∙cm and 423 m ∙g , respectively. The average pore diameter of silica aerogels is 23 nm as the pore specific volume is 1.11 cm ∙g . Further, the contact angle between water droplet and the surface of silica aerogels in specific condition can be as high as 166°, which indicates a super-hydrophobic surface of aerogels.

关键词： silica aerogel     methyltrimethoxysilane     solvent exchange     sodium bicarbonate     trimethylchlorosilane     ambient pressure drying    

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Typical off-design analytical performances of internal combustion engine cogeneration

Xiaohong HE, Ruixian CAI

《能源前沿（英文）》 2009年 第3卷 第2期   页码 184-192 doi: 10.1007/s11708-009-0007-z

摘要： Based on experimental data, typical off-design characteristic curves with corresponding formulas of internal combustion engine (ICE) are summarized and investigated. In combination with analytical solution of single-pressure heat recovery steam generator (HRSG) and influence of ambient pressure on combined heat and power (CHP) system, off-design operation regularities of ICE cogeneration are analyzed. The approach temperature difference Δ , relative steam production and superheated steam temperature decrease with the decrease in engine load. The total energy efficiency, equivalent exergy efficiency and economic exergy efficiency first increase and then decrease. Therefore, there exists an optimum value, corresponding to ICE best efficiency operating condition. It is worth emphasizing that Δ is likely to be negative in low load condition with high design steam parameter and low ICE design exhaust gas temperature. Compared with single shaft gas turbine cogeneration, Δ in ICE cogeneration is more likely to be negative. The main reason for this is that the gas turbine has an increased exhaust gas flow with the decrease in load; while ICE is on the contrary. Moreover, ICE power output and efficiency decrease with the decrease in ambient pressure. Hence, approach temperature difference, relative steam production and superheated steam temperature decrease rapidly while the cogeneration efficiencies decrease slightly. It is necessary to consider the influence of ambient conditions, especially the optimization of ICE performances at different places, on cogeneration performances.

关键词： internal combustion engine (ICE)     cogeneration     heat recovery steam generator (HRSG)     off-design     superheated steam     saturated steam     ambient pressure    

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变环境压力下的激光选区熔化——介观尺度模型与输运现象 Article

胡仁志, 罗曼乐兰, 黄安国, 吴甲民, 魏青松, 文世峰, 张李超, 史玉升, Dmitry Trushnikov, V. Ya. Belenkiy, I. Yu. Letyagin, K.P. Karunakaran, 庞盛永

《工程（英文）》 2021年 第7卷 第8期   页码 1157-1164 doi: 10.1016/j.eng.2021.07.003

摘要：

近期研究表明，相比常压条件下，采用真空或低压环境的激光选区熔化（SLM）工艺可获得缺陷更少、表面质量更优的打印件。虽然通过高速摄像实验已经对SLM工艺在真空环境下的介观物理过程进行了部分研究，但该工艺下影响熔池传热和流动方面的深层机理仍不十分清楚。为此，基于最近的激光焊接模型工作，我们首次建立了变环境压力下SLM工艺的介观尺度数学模型。我们模拟了大气压和100 Pa低压环境下SLM工艺中316L粉末的输运现象。研究发现，在典型工艺参数（激光功率：200 W；扫描速度：2 ms-1；粉末直径：27 µm）下，大气环境中熔池表面凹坑的平均温度将近2800 K，而在100 Pa环境压力时，平均温度仅为2300 K。由于在100 Pa低压条件下，蒸发引起的表面压力和环境压力之间的压差相对于大气环境下的压差更大，更易驱动高温流体流动，因此熔池表面流动速度更加剧烈（平均速度约为4 m·s-1）。研究表明，熔池表面周期性的波浪流动（周期：14 µs）直接影响堆积体的表面粗糙度。此外，由于雷诺数小于400且远低于湍流临界值，熔融金属液流动模式为层流，因此，黏性耗散的影响至关重要。在真空或低环境压力条件下，波纹的流动轨迹更长，使得波动更容易由于黏性效应被耗散，从而改善了打印件的表面粗造度。总之，我们的数学模型阐明了变环境压力下SLM工艺实验研究中观察到的有趣输运现象的物理机制，它有望成为优化SLM工艺过程的有力工具。

关键词： 激光选区熔化     介观尺度模型     环境压力     输运现象    

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Prediction of the theoretical and semi-empirical model of ambient temperature

Foued CHABANE,Noureddine MOUMMI,Abdelhafid BRIMA,Abdelhafid MOUMMI

《能源前沿（英文）》 2016年 第10卷 第3期   页码 268-276 doi: 10.1007/s11708-016-0413-y

摘要： It is well known that the ambient temperature is a sensitive parameter which has a great effect on biology, technology, geology and even on human behavior. A prediction is a statement about an uncertain event. It is often, but not always, based upon experience or knowledge. Although guaranteed accurate information about the future is in many cases impossible, prediction can be useful to assist in making plans about possible developments. As a result, temperature profiles can be developed which accurately represent the expected ambient temperature exposure that this environment experiences during measurement. The ambient temperature over time is modeled based on the previous and data and using a Lagrange interpolation. To observe the comprehensive variation of ambient temperature the profile must be determined numerically. The model proposed in this paper can provide an acceptable way to measure the change in ambient temperature.

关键词： ambient temperature     environment     correlation     theoretical model     semi-empirical    

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Human health ambient water quality criteria for 13 heavy metals and health risk assessment in Taihu Lake

《环境科学与工程前沿（英文）》 2022年 第16卷 第4期 doi: 10.1007/s11783-021-1475-6

摘要：

• The concentrations of 13 heavy metals in Taihu Lake were analyzed.

关键词： Heavy metals     Human health ambient water quality criteria     Taihu Lake     Health risk assessment     Contribution rate    

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Chemisorption solid materials for hydrogen storage near ambient temperature: a review

Yiheng ZHANG, Shaofei WU, Liwei WANG, Xuefeng ZHANG

《能源前沿（英文）》 2023年 第17卷 第1期   页码 72-101 doi: 10.1007/s11708-022-0835-7

摘要： Solid chemisorption technologies for hydrogen storage, especially high-efficiency hydrogen storage of fuel cells in near ambient temperature zone defined from −20 to 100°C, have a great application potential for realizing the global goal of carbon dioxide emission reduction and vision of carbon neutrality. However, there are several challenges to be solved at near ambient temperature, i.e., unclear hydrogen storage mechanism, low sorption capacity, poor sorption kinetics, and complicated synthetic procedures. In this review, the characteristics and modification methods of chemisorption hydrogen storage materials at near ambient temperature are discussed. The interaction between hydrogen and materials is analyzed, including the microscopic, thermodynamic, and mechanical properties. Based on the classification of hydrogen storage metals, the operation temperature zone and temperature shifting methods are discussed. A series of modification and reprocessing methods are summarized, including preparation, synthesis, simulation, and experimental analysis. Finally, perspectives on advanced solid chemisorption materials promising for efficient and scalable hydrogen storage systems are provided.

关键词： hydrogen storage capacity     chemisorption     near-ambient-temperature     modification methods     alloy hydrides    

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Hygroscopicity of ambient submicron particles in urban Hangzhou, China

Jiachen ZHANG, Lin WANG, Jianmin CHEN, Shengmao FENG, Jiandong SHEN, Li JIAO

《环境科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 342-347 doi: 10.1007/s11783-011-0358-7

摘要： In this study, hygroscopicity of size-segregated ambient submicron particles in urban Hangzhou was studied from 28th December 2009 to 18th January 2010, using a hygroscopicity-tandem differential mobility analyzer (H-TDMA). The submicron particles in Hangzhou showed a minor hygroscopic growth at 73% relative humidity (RH), and then grew significantly between 77% and 82% RH. Monomodal distribution accounted for 90% for 30 nm particles, 17% for 50 nm particles, and less than 7% for particles larger than 50 nm at 82% RH. Deconvolution of the bimodal distribution indicated a less hygroscopic group and a more hygroscopic group, with the fraction of the more hygroscopic group increasing with the initial dry particle size and then remaining almost constant for accumulation mode particles. Our results imply that submicron particles in urban Hangzhou were almost entirely externally mixed, and the hygroscopic properties of ambient particles in urban Hangzhou were mainly a function of their size and chemical composition.

关键词： hygroscopicity     hygroscopic tandem differential mobility analyzer (H-TDMA)     submicron ambient particles     Hangzhou    

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Effect of ambient polycyclic aromatic hydrocarbons and nicotine on the structure of Aβ protein

《环境科学与工程前沿（英文）》 2023年 第17卷 第2期 doi: 10.1007/s11783-023-1615-2

摘要：

● B[a]P, nicotine and phenanthrene molecules altered the secondary structure of Aβ42.

关键词： Polycyclic aromatic hydrocarbons     Nicotine     toxicology     Aβ42 peptide     Alzheimer’s disease     Molecular dynamics simulations     Environmental pollution    

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珊瑚岛礁环境噪声成像 Article

夏少红, 张昌榕, 曹敬贺

《工程（英文）》 2023年 第25卷 第6期   页码 182-193 doi: 10.1016/j.eng.2021.09.022

摘要：

As valuable land in the ocean, coral islands are not only important bases for making use of marine resources and protecting marine rights and interests, but also important for breakthrough research in many fields of earth science. Hence, the economical and efficient determination of the underground structure of coral islands has become significant in coral island engineering geology, but remains challenging for traditional marine geophysical prospecting and drilling methods. While ambient noise tomography with dense arrays has been widely used in continental regions, its applicability to coral islands remains undetermined. In this study, based on the data recorded by a dense array on an isolated coral island in the South China Sea, we analyzed the ambient noise characteristics and obtained a 3D subsurface structure of the coral island using ambient noise tomography. We made the following findings: ① The ambient noise frequencies can be roughly categorized into three levels: < 1, 1–5, and > 5 Hz. The spectral characteristics of the noise below 5 Hz were consistent at different stations, but there were significant differences in the characteristics of the noise above 5 Hz. ② For ambient noise frequencies below 5 Hz, cross-correlation functions with high quality could be obtained with only 24 h of waveform data. However, it was difficult to extract meaningful cross-correlation functions for ambient noise frequencies above 5 Hz. ③ The S-wave velocity in the coral island was higher toward the sea and lower toward the lagoon, which was consistent with the high degree of cementation of the outer reef flat stratum on the seaward side. ④ There were two low-velocity horizons at 25–75 and 200–300 m, which were in good agreement with the high-porosity horizons that were revealed by drilling core samples, reflecting the weathering history of the reef. Our research demonstrates that ambient noise tomography is a potentially economical, efficient, and environmentally friendly method for the geological prospecting of coral reefs.

关键词： Coral island     Ambient noise tomography     Engineering geology     South China Sea    

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Hybrid energy harvesting systems for self-powered sustainable water purification by harnessing ambient

《环境科学与工程前沿（英文）》 2023年 第17卷 第10期 doi: 10.1007/s11783-023-1718-9

摘要：

● Energy harvesters harness multiple energies for self-powered water purification.

关键词： Piezocatalysis     Solar energy     Waste heat     Decentralized water treatment     Point-of-use     Nanogenerator    

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Experimental study of modal parameter identification in a simulated ambient-excited structure

JI Xiaodong, QIAN Jiaru, XU Longhe

《结构与土木工程前沿（英文）》 2007年 第1卷 第3期   页码 281-285 doi: 10.1007/s11709-007-0036-9

摘要： Structure modal parameter online identification was used to monitor the structural health as evidenced by changes in the vibration characteristics. The natural excitation technique and the eigensystem realization algorithm were combined to identify the modal parameters in the time domain of a structure excited by simulated ambient vibrations. The mass-normalized mode shapes were obtained from the eigen-sensitivity analysis. The experimental modal analysis was performed on a two-story steel braced frame model excited by simulated ambient vibrations and hammer impacts. The mass-normalized mode shapes were acquired by changing the structural mass and by eigen-sensitivity analy sis. From finite element analysis results and the experimental data, it is shown that this method is effective.

关键词： eigensystem realization     eigen-sensitivity analysis     realization algorithm     vibration     effective    

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Evaluating the short-term effect of ambient temperature on non-fatal outdoor falls and road traffic injuries

《环境科学与工程前沿（英文）》 2023年 第17卷 第9期 doi: 10.1007/s11783-023-1705-1

摘要：

● A study assessing the temperature-injury relationship was conducted among students.

关键词： Ambient temperature     Fall     Road traffic injury     Student     China    

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iterative data enhancement for implementation in purification of modal frequency for extremely noisy ambient

Hassan YOUSEFI, Alireza TAGHAVI KANI, Iradj MAHMOUDZADEH KANI, Soheil MOHAMMADI

《结构与土木工程前沿（英文）》 2020年 第14卷 第2期   页码 446-472 doi: 10.1007/s11709-019-0605-8

摘要： The main purpose of the present study is to enhance high-level noisy data by a wavelet-based iterative filtering algorithm for identification of natural frequencies during ambient wind vibrational tests on a petrochemical process tower. Most of denoising methods fail to filter such noise properly. Both the signal-to-noise ratio and the peak signal-to-noise ratio are small. Multiresolution-based one-step and variational-based filtering methods fail to denoise properly with thresholds obtained by theoretical or empirical method. Due to the fact that it is impossible to completely denoise such high-level noisy data, the enhancing approach is used to improve the data quality, which is the main novelty from the application point of view here. For this iterative method, a simple computational approach is proposed to estimate the dynamic threshold values. Hence, different thresholds can be obtained for different recorded signals in one ambient test. This is in contrast to commonly used approaches recommending one global threshold estimated mainly by an empirical method. After the enhancements, modal frequencies are directly detected by the cross wavelet transform (XWT), the spectral power density and autocorrelation of wavelet coefficients. Estimated frequencies are then compared with those of an undamaged-model, simulated by the finite element method.

关键词： ambient vibration test     high level noise     iterative signal enhancement     wavelet     cross and autocorrelation of wavelets    

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Single particle analysis of ambient aerosols in Shanghai during the World Exposition, 2010: two case

Shikang TAO, Xinning WANG, Hong CHEN, Xin YANG, Mei LI, Lei LI, Zhen ZHOU

《环境科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 391-401 doi: 10.1007/s11783-011-0355-x

摘要： A TSI Model 3800 aerosol time-of-flight mass spectrometer (ATOFMS) was deployed for single-particle analysis in Shanghai during the World Exposition (EXPO), 2010. Measurements on two extreme cases: polluted day (1st May) and clean day (25th September) were compared to show how meteorological conditions affected the concentration and composition of ambient aerosols. Mass spectra of 90496 and 50407 particles were analyzed respectively during the two sampling periods. The ART-2a neural network algorithm was applied to sort the collected particles. Seven major classes of particles were obtained: dust, sea salt, industrial, biomass burning, organic carbon (OC), elementary carbon (EC), and NH -rich particles. Number concentration of ambient aerosols showed a strong anti-correlation with the boundary layer height variation. The external mixing states of aerosols were quite different during two sampling periods because of different air parcel trajectories. Number fraction of biomass burning particles (43.3%) during polluted episode was much higher than that (21.6%) of clean time. Air parcels from the East China Sea on clean day diluted local pollutant concentration and increased the portion of sea salt particle dramatically (13.3%). The large contribution of biomass burning particles in both cases might be an indication of a constant regional background of biomass burning emission. Mass spectrum analysis showed that chemical compositions and internal mixing states of almost all the particle types were more complicate during polluted episode compared with those observed in clean time. Strong nitrate signals in the mass spectra suggested that most of the particles collected on polluted day had gone through some aging processes before reaching the sampling site.

关键词： ambient aerosol     aerosol time-of-flight mass spectrometer     Shanghai     world exposition    

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A new damage quantification approach for shear-wall buildings using ambient vibration data

Seung-Hun SUNG,Hyung-Jo JUNG

《结构与土木工程前沿（英文）》 2015年 第9卷 第1期   页码 17-25 doi: 10.1007/s11709-014-0278-2

摘要： This paper presents a new approach to estimate damage severity for shear-wall buildings using diagonal terms of a modal flexibility matrix estimated from dynamic properties. This study aims to provide a fundamental concept for quantifying the damage of realistic buildings by investigating an idealized shear-wall building. Numerical studies were performed on a 5-story shear-wall building model to validate the applicability of the presented approach, using two damage patterns. With the numerical simulations, the proposed approach accurately determined the damage ratio of the specimens. Experiments were also conducted on a 5-story shear-wall building model for which the system parameters were almost the same as those in numerical simulations. The estimated damage-quantification results from the experimental validations demonstrated that the performance of the presented method for shear-wall buildings was both suitable and accurate.

关键词： damage identification     modal flexibility     damage quantification     shear-wall buildings    

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标题 作者 时间 类型 操作

Effect of sodium bicarbonate solution on methyltrimethoxysilane-derived silica aerogels dried at ambientpressure

Yujing Liu, Xiao Han, Balati Kuerbanjiang, Vlado K. Lazarov, Lidija Šiller

期刊论文

Typical off-design analytical performances of internal combustion engine cogeneration

Xiaohong HE, Ruixian CAI

期刊论文

变环境压力下的激光选区熔化——介观尺度模型与输运现象

胡仁志, 罗曼乐兰, 黄安国, 吴甲民, 魏青松, 文世峰, 张李超, 史玉升, Dmitry Trushnikov, V. Ya. Belenkiy, I. Yu. Letyagin, K.P. Karunakaran, 庞盛永

期刊论文

Prediction of the theoretical and semi-empirical model of ambient temperature

Foued CHABANE,Noureddine MOUMMI,Abdelhafid BRIMA,Abdelhafid MOUMMI

期刊论文

Human health ambient water quality criteria for 13 heavy metals and health risk assessment in Taihu Lake

期刊论文

Chemisorption solid materials for hydrogen storage near ambient temperature: a review

Yiheng ZHANG, Shaofei WU, Liwei WANG, Xuefeng ZHANG

期刊论文

Hygroscopicity of ambient submicron particles in urban Hangzhou, China

Jiachen ZHANG, Lin WANG, Jianmin CHEN, Shengmao FENG, Jiandong SHEN, Li JIAO

期刊论文

Effect of ambient polycyclic aromatic hydrocarbons and nicotine on the structure of Aβ protein

期刊论文

珊瑚岛礁环境噪声成像

夏少红, 张昌榕, 曹敬贺

期刊论文

Hybrid energy harvesting systems for self-powered sustainable water purification by harnessing ambient

期刊论文

Experimental study of modal parameter identification in a simulated ambient-excited structure

JI Xiaodong, QIAN Jiaru, XU Longhe

期刊论文

Evaluating the short-term effect of ambient temperature on non-fatal outdoor falls and road traffic injuries

期刊论文

iterative data enhancement for implementation in purification of modal frequency for extremely noisy ambient

Hassan YOUSEFI, Alireza TAGHAVI KANI, Iradj MAHMOUDZADEH KANI, Soheil MOHAMMADI

期刊论文

Single particle analysis of ambient aerosols in Shanghai during the World Exposition, 2010: two case

Shikang TAO, Xinning WANG, Hong CHEN, Xin YANG, Mei LI, Lei LI, Zhen ZHOU

期刊论文

A new damage quantification approach for shear-wall buildings using ambient vibration data

Seung-Hun SUNG,Hyung-Jo JUNG

期刊论文