检索结果-南通市图书馆

A numerical simulation study on mechanical behaviour of coal with bedding planes under coupled static and dynamic load

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2018年第5期28卷 791-797页

作者： Lihai Tan Ting Ren Xiaohan Yang Xueqiu He school of Civil Mining and Environmental Engineering University of Wollongong school of Resources and Safety engineering Central South University school of Civil and environmental engineering University of Science and TechnologyBeijing

To investigate the bedding influence on coal mechanical behaviour in underground environments such as coal or rock burst, simulations of dynamic SHPB tests of pre-stressed coal specimens with different bedding angles were carried out using a particle flow code 2-dimensional(PFC2D). Three impact velocities of 4, 8 and 12 m/s were selected to study dynamic behaviours of coal containing bedding planes under different dynamic loads. The simulation results showed that the existence of bedding planes leads to the degradation of the mechanical properties and their weakening effect significantly depends on the angle h between the bedding planes and load direction. With h increaseing from 0° to 90°, the strength first decreased and subsequently increased and specimens became most vulnerable when h was 30° or 45°.Five failure modes were observed in the specimens in the context of macro-cracks. Furthermore, energy characteristics combined with ultimate failure patterns revealed that maximum accumulated energy and failure intensity have a positive relation with the strength of specimen. When bedding planes were parallel or perpendicular to loading direction, specimens absorbed more energy and experienced more violent failure with increased number of cracks. In contrast, bedding planes with h of 30° or 45° reduced the specimens' ability of storing strain energy to the lowest with fewer cracks observed after failure.

关键词： Static–dynamic coupled loads SHPB Coal bedding angle Strain energy PFC2D

Metabolites change of Scenedesmus obliquus exerted by AgNPs

在线全文

学校读者我要写书评

暂无评论

Journal of environmental Sciences 2019年第2期31卷 310-318页

作者： Pu Wang Bo Zhang Hui Zhang Yiliang He Choon Nam Ong Jun Yang school of environmental Science & engineering Shanghai Jiaotong University school of Municipal and environmental engineering Lanzhou Jiaotong University NUS environmental Research Institute National University of Singapore

With increasing emission of silver nanoparticles(AgNPs) into the environment, it is important to understand the effects of ambient concentration of AgNPs. The biological effects of AgNPs on Scenedesmus obliquus, a ubiquitous freshwater microalgae, was evaluated. AgNPs exerted a minor inhibitory effect at low doses. Non-targeted metabolomic studies were conducted to understand and analyze the effect of AgNPs on algal cells from a molecular perspective. During the 48 hr of exposure to AgNPs, 30 metabolites were identified, of which nine had significant changes compared to the control group. These include D-galactose, sucrose, and *** carbohydrates are involved in the synthesis and repair of cell walls. Glycine, an important constituent amino acid of glutathione, increased with AgNP exposure concentration increasing, likely to counteract an increased intracellular oxidative stress. These results provide a new understanding of the toxicity effects and mechanism of AgNPs. These metabolites could be useful biomarkers for future research, employed in the early detection of environmental risk from AgNPs.

关键词： Silver nanoparticles (AgNPs) Scenedesmus obliquus Metabolomics Molecular mechanism

Two-dimensional correlation spectroscopic analysis on the interaction between humic acids and aluminum coagulant

在线全文

学校读者我要写书评

暂无评论

Journal of environmental Sciences 2018年第2期30卷 181-189页

作者： Pengkang Jin Jina Song Xiaochang C.Wang Xin Jin school of environmental and Municipal engineering Xi'an University of Architecture and Technology College of Energy and environmental engineering Hebei University of Engineering

In this study, two-dimensional correlation spectroscopy integrated with synchronous fluorescence and infrared absorption spectroscopy was employed to investigate the interaction between humic acids and aluminum coagulant at slightly acidic and neutral p H. Higher fluorescence quenching was produced for fulvic-like and humic-like fractions at p H 5. At p H 5, the humic-like fractions originating from the carboxylic acid, carboxyl and polysaccharide compounds were bound to aluminum first, followed by the fulvic-like fractions originating from the carboxyl and polysaccharide compounds. This finding also demonstrated that the activated functional groups of HA were involved in forming the Al-HA complex, which was accompanied by the removal of other groups by ***, at p H 7, almost no fluorescence quenching occurred, and surface complexation was observed to occur, in which the activated functional groups were absorbed on the amorphous Al（OH）3. Two-dimensional FT-IR correlation spectroscopy indicated the sequence of HA structural change during coagulation with aluminum, with IR bands affected in the order of COOH〉 COO-〉NH deformation of amide Ⅱ〉 aliphatic hydroxyl C／OH at p H 5, and COO-〉aliphatic hydroxyl C／OH at p H 7. This study provides a promising pathway for analysis and insight into the priority of functional groups in the interaction between organic matters and metal coagulants.

关键词： Two-dimensional correlation spectroscopy Al-HA complex Surface complexation Interaction sequence

Effects of land use change and water reuse options on urban water cycle

在线全文

学校读者我要写书评

暂无评论

Journal of environmental Sciences 2010年第6期22卷 923-928页

作者： Jiho Lee Gijung Pak Chulsang Yoo Sangdan Kim Jaeyoung Yoon school of Civil Environmentaland Architectural EngineeringKorea University Department of environmental engineering Korea University Department of environmental System engineering Pukyong National University

The aim of this article was to study the effects of land use change and water reuse options on an urban water cycle. A water cycle analysis was performed on the Goonja drainage basin, located in metropolitan Seoul, using the Aquacycle model. The chronological effects of urbanization were first assessed for the land uses of the Goonja drainage basin from 1975 to 2005, where the ratio of impervious areas ranged from 43% to 84%. Progressive urbanization was identified as leading to a decrease in evapotranspiration （29%）, an increase in surface runoff （41%） and a decrease in groundwater recharge （74%）, indicating a serious distortion of the water cycle. From a subsequent analysis of the water reuse options, such as rainwater use and wastewater reuse, it is concluded that wastewater reuse seemed to have an advantage over rainwater use for providing a consistent water supply throughout the year for a country like Korea. where the rainy season is concentrated during the summer monsoon.

关键词： Aquacycle model land use change water reuse

Improvement of stability of trivalent chromium electroplating of Ti based IrO_2+Ta_2O_5 coating anodes

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第z1期25卷 645-649页

作者： LI Baosong LIN An GAN Fuxing Department of environmental engineering School of Resource and Environmental Science Wuhan University Wuhan 430079 China Department of Environmental Engineering School of Resource and Environmental Science Wuhan University Wuhan 430079 China Department of Environmental Engineering School of Resource and Environmental Science Wuhan University Wuhan 430079 China

The preparation process and properties of the thermally prepared Ti anodes coated with IrO2+Ta2O5 was studied. The structure and morphologies of the IrO2+Ta2O5 coatings were determined by XRD and SEM. Their electrochemical properties were studied by polarization curve and cyclic voltammetry. Trivalent chromium electroplating using Ti/IrO2+Ta2O5 anodes is carried out and the results were analyzed. Results show that this anode exhibits excellent electrochemical activity and stability in sulfate electrolysis. The electrocatalytic activity is determined not only by the content of IrO2 but also the structure and morphology of the anode coatings. The electroplating results indicats that Ti/IrO2+Ta2O5 anodes have excellent capabilities and merits in improving the stability of trivalent chromium electroplating in sulfate system.

关键词： IrO2+Ta2O5 trivalent chromium electroplating oxygen evolution oxide coated anode

Thermogravimetric characteristics and different kinetic models for medical waste composition containing polyvinyl chloride-transfusion tube

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2014年第3期21卷 1034-1043页

作者：邓娜王维维崔文谦张于峰马洪亭 school of environmental engineering Tianjin University

Thermogravimetric study of medical transfusion tube （MTT） waste containing polyvinyl chloride （PVC） was carried out using the thermogravimetric analyser （TGA） with N2, at different heating rates of 5, 10, 20, 30, 50 ℃/min. The purpose is to obtain pyrolysis characteristics and kinetic parameters of medical waste. The experimental results indicate that the pyrolysis behavior of the MTT sample is in agreement with its main ingredient of PVC, appearing two stair stepping stages. The influence of the additives in MTT on pyrolysis behavior was also revealed, which could improve MTT pyrolysis at lower temperature in the first stage, and cause obvious unsmoothness and asymmetry of the second DTG peak. Four n-order kinetic models of Coats-Redfern, Ozawa, Kissinger and Freeman-carroll were used to get the kinetic parameters. Furthermore, a novel ＂two-step four-reaction model＂ was established to simulate the whole continuous process. The different methods and the kinetic parameters thus obtained were discussed and compared with each other in literatures. The reasons of deviation among kinetic values were tried to be elucidated. The new established model could more satisfactorily describe the pyrolysis process of MTT, being more mechanistic and conveniently serving for the engineering.

关键词： medical waste polyvinyl chloride (PVC) medical transfusion tube (MTT) pyrolysis characteristics model

Performance of the hybrid growth sequencing batch reactor(HG-SBR) for biodegradation of phenol under various toxicity conditions

在线全文

学校读者我要写书评

暂无评论

Journal of environmental Sciences 2019年第1期31卷 64-72页

作者： NikAthirah Yusoff Soon-An Ong Li-Ngee Ho Yee-Shian Wong Farah Naemah Mohd Saad WanFadhilah Khalik Sin-Li Lee school of environmental engineering University Malaysia Perlis school of Materials engineering University Malaysia Perlis

Hybrid growth microorganisms in sequencing batch reactors have proven effective for treating the toxic compound phenol, but the toxicity effect under different toxicity conditions has rarely been discussed. Therefore, the performance of the HG-SBR under toxic, acute and chronic organic loading can provide the overall operating conditions of the system. Toxic organic loading(TOL) was monitored during the first 7 hr while introducing50 mg/L phenol to the system. The system was adversely affected with the sudden introduction of phenol to the virgin activated sludge, which caused a low degradation rate and high dissolved oxygen consumption during TOL. Acute organic loading(AOL) had significant effects at high phenol concentrations(600, 800 1000 mg/L). The specific oxygen uptake rate(SOUR) gradually decreased to 4.9 mg O_2/(g MLVSS·hr) at 1000 mg/L of phenol compared to 12.74 mg O_2/(g MLVSS·hr) for 200 mg/L of phenol. The HG-SBR was further monitored during chronic organic loading(COL) over 67 days. The effects of organic loading were more apparent at 800 mg/L and 1000 mg/L phenol concentrations, as the removal range was between 22%–30% and 18%–46% respectively, which indicated the severe effects of COL.

关键词： Toxic organic loading Acute organic loading Chronic organic loading Phenol Sequencing batch reactor

High-resolution modeling and evaluation of ozone air quality of Osaka using MM5-CMAQ system

在线全文

学校读者我要写书评

暂无评论

Journal of environmental Sciences 2009年第6期21卷 782-789页

作者： SHRESTHA Kundan Lal KONDO Akira KAGA Akikazu INOUE Yoshio Division of Sustainable Energy and environmental engineering School of EngineeringOsaka University

High-resolution modeling approach is increasingly being considered as a necessary step for improving the monitoring and predictions of regional air quality. This is especially true for highly urbanized region with complex terrain and land-use. This study uses Community Multiscale Air Quality （CMAQ） model coupled with MM5 mesoscale model for a comprehensive analysis to assess the suitability of such high-resolution modeling system in predicting ozone air quality in the complex terrains of Osaka, Japan. The 1-km and 3-kin grid domains were nested inside a 9-km domain and the domain with 1-km grid covered the Osaka region. High-resolution Grid Point Value-Mesoscale Model （GPV-MSM） data were used after suitable validation. The simulated ozone concentrations were validated and evaluated using statistical metrics using performance criteria set for ozone. Daily maxima of ozone were found better simulated by the 1-krn grid domain than the coarser 9-km and 3-km domains, with the maximum improvement in the mean absolute gross error about 3 ppbv. In addition, 1-km grid results fared better than other grids at most of the observation stations that showed noticeable differences in gross error as well as correlation. These results amply justify the use of the integrated high-resolution MM5-CMAQ modeling system in the highly urbanized region, such as the Osaka region, which has complex terrain and land-use.

关键词： air quality model evaluation ozone Community Multiscale Air Quality MM5 statistical analysis

Photoelectrochemical glucose biosensor incorporating CdS nanoparticles

在线全文

学校读者我要写书评

暂无评论

Particuology 2009年第5期7卷 347-352页

作者： Jinjie Sun Yihua Zhu Xiaoling Yang Chunzhong Li Key Laboratory for Ultrafine Materials of Ministry of Education School of Materials Sdence and EngineeringEast China University of Science and Technology 130 Meilong Road. Shanghai 200237 China

A novel photoelectrochemical biosensor incorporating nanosized CdS semiconductor crystals with enzyme to enhance photochemical reaction has been investigated. CdS nanoparticles were synthesized by using dendrimer PAMAM as inner templates. The CdS nanoparticles and glucose oxidase （GOD） were immobilized on Pt electrode via layer-by-layer （LbL） technique to fabricate a biological-inorganic hybrid system. Under ultraviolet light, the photo-effect of the CdS nanoparticles showed enhancement of the biosensor to detect glucose. Pt nanoparticles were mixed into the Nation film to immobilize the CdS/enzyme composites and to improve the charge transfer of the hybrid. Experimental results demonstrate the desirable characteristics of this biosensing system, e,g. a sensitivity of 1.83 μA/（mM cm^2）, lower detection limit （1 μM）, and acceptable reproducibility and stability,

关键词： CdS nanoparticles PAMAM Photoelectrochemical Biosensor Glucose oxidase Layer-by-layer