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Effect of a seasonal diffuse pollution migration on natural organic matter behavior in a stratified dam reservoir

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Journal of Environmental Sciences 2010年第6期22卷 908-914页

作者： Soon Ju Yu Jae Yil Lee Sung Ryong ha National Institute of Environmental Research Department of Urban Engineering Chungbuk National University

This article aims to describe the influence of diffuse pollution on the temporal and spatial characteristics of natural organic matter （NOM） in a stratified dam reservoir, the Daecheong Dam, on the basis of intensive observation results and the dynamic water quality simulation using CE-QUAL-W2. Turbidity is regarded as a comprehensive representation of allochothonous organic matter from diffuse sources in storm season because the turbidity concentration showed reasonable significance in a statistical correlation with the UV absorbance at 254 nm and total phosphorus. CE-QUAL-W2 simulation results showed good consistency with the observed data in terms of dissolved organic matter （DOM） including refractory dissolved organic carbon （RDOC） and labile DOC and also well explained the internal movement of constituents and stratification phenomenon in the reservoir. Instead turbidity and NOM were related well in the upper region of the reservoir according to flow distance, gradually as changing to dissolved form of organic matter, RDOM affected organic matter concentration of reservoir water quality compared to turbidity. To control the increase of soluble organic matters in the dam reservoir, appropriate dam water discharge gate operation provided effective measurement. Because of the gate operation let avoid the accumulation of organic matter within a dam reservoir by shorten of turbid regime retention time.

关键词： CE-QUQL-W2 natural organic matter stratified dam reservoir turbidity flow

Predicting Concrete Compressive Strength Using Deep Convolutional Neural Network Based on Image Characteristics

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Computers, Materials & Continua 2020年第10期65卷 1-17页

作者： Sanghyo Lee Yonghan Ahn ha Young Kim Division of Architecture and Civil Engineering Kangwon National UniversitySamcheok-si25913Korea School of Architecture and Architectural Engineering Hanyang University ERICAAnsan-si15588Korea Graduate School of Information Yonsei UniversitySeoul03722Korea

In this study,we examined the efficacy of a deep convolutional neural network(DCNN)in recognizing concrete surface images and predicting the compressive strength of concrete.A digital single-lens reflex(DSLR)camera and microscope were simultaneously used to obtain concrete surface images used as the input data for the ***,training,validation,and testing of the DCNNs were performed based on the DSLR camera and microscope image *** of the analysis indicated that the DCNN employing DSLR image data achieved a relatively higher *** accuracy of the DSLR-derived image data was attributed to the relatively wider range of the DSLR camera,which was beneficial for extracting a larger number of ***,the DSLR camera procured more realistic images than the ***,when the compressive strength of concrete was evaluated using the DCNN employing a DSLR camera,time and cost were reduced,whereas the usefulness ***,an indirect comparison of the accuracy of the DCNN with that of existing non-destructive methods for evaluating the strength of concrete proved the reliability of DCNN-derived concrete strength *** addition,it was determined that the DCNN used for concrete strength evaluations in this study can be further expanded to detect and evaluate various deteriorative factors that affect the durability of structures,such as salt damage,carbonation,sulfation,corrosion,and freezing-thawing.

关键词： Deep convolutional neural network(DCNN) non-destructive testing(NDT) concrete compressive strength digital single-lens reflex(DSLR)camera microscope

Multiresponsive Spin Crossover Driven by Rotation of Tetraphenylborate Anion in an Iron(Ⅲ)Complex

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CCS Chemistry 2021年第1期3卷 453-459页

作者： Si-GuoWu Md.Najbul Hoque Jie-Yu Zheng Guo-Zhang Huang Nguyen vu ha Anh Liviu Ungur Wei-Xiong Zhang Zhao-Ping Ni Ming-Liang Tong Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education School of ChemistrySun Yat-Sen UniversityGuangzhou 510275 Department of Chemistry National University of SingaporeSingapore 117543

Dynamic molecular materials,which involvemechanical motions in crystals,usually exhibit tunable properties related to conformational ***,we describe a solvent-free molecular crystal[{FeⅢ(salten)}2(TPB)](BPh_(4))_(2)(Ⅰ)developed by associating the rotatable tetraphenylborate anion with the spin crossover(SCO)binuclear iron(Ⅲ)*** solvent-free phaseⅠcan undergo a temperature-induced phase transformation to phaseⅡ,during which rotation of the BPh4−anion interplays with the SCO component,giving rise to fascinating variations in SCO(from gradual to abrupt)and dielectric *** importantly,an unexpected polymorphic transformation fromⅡtoⅢorⅣ,with increasing magnetic hysteresis,is realized by exposingⅡto water or ethanol vapor;the transition is reversible by *** rare successive transformation is further rationalized by theoretical ***,this multiresponse system provides a new way for modulating synergistic effects and designing dynamic SCO materials by integrating intramolecular motions in the crtystal lattice.

关键词： intramolecular motion iron(Ⅲ) spin crossover polymorph single-crystal-to-singlecrystal transformation

Probability mass first flush evaluation for combined sewer discharges

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Journal of Environmental Sciences 2010年第6期22卷 915-922页

作者： Inhyeok Park Hongmyeong Kim Soo-Kwon Chae Sungryong ha Department of Urban Engineering Chungbuk National University Ecowiz Corporation Cheongju School of Human & Environmental Sciences Eulji University

The Korea government has put in a lot of effort to construct sanitation facilities for controlling non-point source pollution. The first flush phenomenon is a prime example of such pollution. However, to date, several serious problems have arisen in the operation and treatment effectiveness of these facilities due to unsuitable design flow volumes and pollution loads. It is difficult to assess the optimal flow volume and pollution mass when considering both monetary and temporal limitations. The objective of this article was to characterize the discharge of storm runoff pollution from urban catchments in Korea and to estimate the probability of mass first flush （MFFn） using the storm water management model and probability density functions. As a result of the review of gauged storms for the representative using probability density function with rainfall volumes during the last two years, all the gauged storms were found to be valid representative precipitation. Both the observed MFFn and probability MFFn in BE-1 denoted similarly large magnitudes of first flush with roughly 40% of the total pollution mass contained in the first 20% of the runoff. In the case of BE-2, however, there were significant difference between the observed MFFn and probability MFFn.

关键词： first flush combined sewer overflows (CSOs) probability mass first flush storm water management model best management practices

Investigation of Punch Resistance of the Allomyrira dichtoloma Beetle Forewing

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Journal of Bionic Engineering 2018年第1期15卷 57-68页

作者： Ngoc San ha Vinh Tung Le Nam Seo Goo Smart Microsystem Research Laboratory Department of Advanced Technology Fusion Division of Interdisciplinary Studies Konkuk University Seou105029 Republic of Korea Faculty of Science Engineering and Technology Swinburne University of Technology Hawthorn VIC 3122 Australia

In this study, the punch resistance of the beetle forewing was investigated to address the ability of the forewing against the external force. The punch resistance of the forewing was measured for different sizes and sexes of beetles using a conventional testing method in conjunction with the Digital Image Correlation （DIC） technique. The results showed that the maximum fracture load was measured around 23 N for the female beetle and around 20.2 N for the male beetle in the front-side punch test. Moreover, the fracture load in the front-side punch test was higher than that in the back-side punch test for both male and female beetles. This means that the beetle forewing plays a protection role against external loads. Furthermore, the puncture energy in the front-side punch test for the female beetle （6.91 m J） was a little higher than that for the male beetle （5.27 mJ）. In addition, the DIC results revealed that the first crack occurred along the trachea line and the second crack then appeared in the direction that was perpendicular to the direction of the first crack. This study provides a com- prehensive understanding of the mechanical protection properties of the beetle forewing and offers a good lesson for studying lightweight bio-inspired composite material.

关键词： beetle forewing punch test punch energy digital image correlation

A voltage-controlled chaotic oscillator based on carbon nanotube field-effect transistor for low-power embedded systems

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Chinese Physics B 2014年第5期23卷 617-622页

作者： Van ha Nguyen Wonkyeong Park Namtae Kim hanjung Song Department of Nano Systems Engineering Inje University Department of Electronics Engineering Inje University Center for Nano Manufacturing Inje University

This paper presents a compact and low-power-based discrete-time chaotic oscillator based on a carbon nanotube field-effect transistor implemented using Wong and Deng＇s well-known model. The chaotic circuit is composed of a nonlinear circuit that creates an adjustable chaos map, two sample and hold cells for capture and delay functions, and a voltage shifter that works as a buffer and adjusts the output voltage for feedback. The operation of the chaotic circuit is verified with the SPICE software package, which uses a supply voltage of 0.9 V at a frequency of 20 kHz. The time series, frequency spectra, transitions in phase space, sensitivity with the initial condition diagrams, and bifurcation phenomena are presented. The main advantage of this circuit is that its chaotic signal can be generated while dissipating approximately 7.8 μW of power, making it suitable for embedded systems where many chaos-signal generators are required on a single chip.

关键词： chaos generator carbon nanotube field-effect transistor bifurcation random noise generator

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境外矿业投资项目风险管理研究

工程设计与施工 2024年第8期6卷 149-151页

作者：宋海波哈志勇中咨工程管理咨询有限公司北京100000

论文研究提出境外矿业投资项目风险除具有一般项目风险特征外,还有阶段性、复杂性和长期性等特征,并对上述特征进行了分析。论文结合境外矿业投资项目建设内容和实施特点,将其生命周期划分为投资决策阶段、项目准备阶段、施工建设阶段... 详细信息

论文研究提出境外矿业投资项目风险除具有一般项目风险特征外,还有阶段性、复杂性和长期性等特征,并对上述特征进行了分析。论文结合境外矿业投资项目建设内容和实施特点,将其生命周期划分为投资决策阶段、项目准备阶段、施工建设阶段和运营阶段,在此基础上对各个阶段主要风险因素进行识别,同时分析了相应的风险事件和可能对项目造成的影响。为了更好地防范和化解境外矿业投资项目风险,论文针对政策法规、市场、管理、社会治安和工期等风险制定应对措施。

关键词：境外投资矿业项目风险管理

Oxidative coupling of methane over LaAlO3 perovskite catalysts prepared by a co-precipitation method: Effect of co-precipitation pH value

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Journal of Energy Chemistry 2019年第8期28卷 1-8,I0001页

作者： Yujin Sim Jihoon Yoo Jeong-Myeong ha Ji Chul Jung Department of Chemical Engineering Myongji UniversityYongin 17058 Republic of Korea Clean Energy Research Center Korea Institute of Science and TechnologySeoul 02792 Republic of Korea

Oxidative coupling of methane(OCM) was conducted over LaAlO3X catalysts that were prepared by a coprecipitation method using different co-precipitation pH values(X = 6–10). The aim is to investigate the effect of p H values on the catalytic activity of La AlO3 catalysts in this reaction. The results showed that the co-precipitation pH value affected greatly on the formation of chemical species of precipitate precursors in the co-precipitation step, leading to different phases of the finally obtained LaAlO3 *** the co-precipitation pH value increased up to 8, the lanthanum-related phases such as La2 O3 and La(OH)3 were gradually formed as by-products, preventing the formation of LaAlO3 perovskite crystalline structure and facilitating the formation of oxygen vacancies on catalyst surface. However, at pH value of9 or higher, the lanthanum content in the precipitate precursor was increased greatly. Not LaAlO3 perovskite but lanthanum-related phases were developed as main phases, reducing their catalytic activities in this reaction. Among LaAlO3 catalysts, the one prepared at pH = 8 showed the highest C2 yield due to its well-developed oxygen vacancies and electrophilic lattice oxygen. Therefore, the co-precipitation pH value strongly affected the LaAlO3 catalyst activity in OCM reaction. A precious pH control should be required to prepare various perovskite catalysts for the OCM.

关键词： LaAlO3 Perovskite Oxidative coupling of methane Co-precipitation pH value

Porous Iron Single Crystals at 2 cm Scale Delivering Enhanced Electrocatalysis Performance

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Chinese Journal of Structural Chemistry 2020年第11期39卷 2033-2040页

作者： CHENG Fang-Yuan MYUNG Jae-ha XIE Kui College of Chemistry and Materials Science Fujian Normal UniversityFuzhou 350007China Key Laboratory of Design&Assembly of Functional Nanostructures Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China

Porous single crystals would significantly enhance their catalysis functionalities owing to the combination of structural coherence and porous microstructures. Porous single crystals have wormhole microstructures and then we define them as wormcrystals. The twisted surfaces in porous microstructures would produce surface lattice distortions that give rise to high-energy active surfaces. Here we grow porous iron single crystals at an unprecedented 2 cm scale with a lattice reconstruction strategy and create high-energy surfaces through the control of lattice distortions within a thickness region of 1~2 nm. The porous iron crystal therefore boosts electrochemical reduction of nitrobenzene to aminobenzene with ~100% conversion and > 95% selectivity. The exceptionally high current densities with porous iron crystals represent the first level electrocatalysis performance. The current work would open a new pathway not only to the creation of high energy surfaces but also to the growth of porous single crystals at large scales in wealth of other materials.

关键词： porous single crystals twisted surfaces lattice distortions electrocatalysis