摘要：
Biosorption has been developed as an effective and economic method to treat wastewater containing low concentrations of metal pollutants. In this study, a bacterium, Citrobacter freudii, was used as a biosorbent to adsorb uranium ions. The thermodynamics and kinetics of this adsorption, as well as its mechanism, were investigated. The results indicated that the biosorption rate could be better described by a pseudo 2nd-order model than a pseudo 1st-order model. The adsorption of U (VI) proceeded very rapidly in the first 30 min and subsequently slowed down continuously for a long period. The biosorption isotherm of uranium by C. freudii could be described well by the Langmuir or Freundlich isotherm, and the latter was better. The thermodynamics parameters, Delta H degrees, Delta G degrees, and Delta S degrees were calculated according to the results of the experiment, which showed this biosorption as being endothermic and spontaneous. The authors investigated the active sites of bacteria for biosorption and the results proved that carboxyl in the cell wall played an important role in biosorption. (c) 2007 Elsevier Ltd. All rights reserved.
摘要：
The application of high-strength concrete (HSC) in high-rise structures is becoming an increasingly used practice. In order to improve the ductility of HSC, many studies are conducted worldwide. In this paper, the effect of ultra-high-strength reinforcement on the seismic behaviour of HSC columns is investigated through numerical analysis and experiments. The results of the numerical analysis are compared with the experimental results. The comparison shows that the numerical analysis results agree very well with the experiments. The results also show that the flexural behaviour of the columns can be effectively improved by use of mixed ultra-high-strength steel bars with a yield strength above 1000 MPa and normal-strength steel bars for the longitudinal reinforcement. Moreover, the test also shows that the ductility of HSC columns, which are reinforced by an ultra-strength stirrup rebar, is better than that of a column which is confined by the normal reinforcement, especially in the case of high-strength concrete columns with compression strength above C60. Finally, an experiential formula for the ductility, which is related to the yield strength of ultra-high-strength steel bars, was derived on the basic of test data and numerical analysis results.
作者：
Xie Dong*;Wang Han-qing;Deng Qi-hong;Xiong Jun
期刊：
中南大学学报(英文版),2007年14:66-70 ISSN：2095-2899
通讯作者：
Xie Dong
作者机构：
[Xie Dong; Deng Qi-hong] Cent S Univ, Sch Energy Sci & Engn, Changsha 410083, Peoples R China.;[Xie Dong; Xiong Jun] Univ S China, Sch Urban Construct, Hengyang 421001, Peoples R China.;[Wang Han-qing] Hunan Univ Technol, Dept Civil Engn, Zhuzhou 412008, Peoples R China.
通讯机构：
[Xie Dong] C;Cent S Univ, Sch Energy Sci & Engn, Changsha 410083, Peoples R China.
关键词：
indoor air environment;ventilation patterns;numerical simulation;human comfort
摘要：
The different ventilation patterns inside a room containing one person and office furniture arranged by different inlet/outlet configurations was investigated. The numerical simulation was first adopted to predict air flow pattern and ventilation performance. Then, a laboratory experimental measurement at room air distribution in a fall-scale test chamber was conducted using the hot wire velocimetry to validate the simulation results. In addition, questionnaire surveys were conducted from the different gender groups in order to assess indoor air quality and human comfort in workplace micro-environments. The distribution of supply/exhaust air in the study was investigated in isothermal conditions using different supply air velocities. The results indicate that the ventilation efficiency and human comfort might be dominantly influenced by location of diffuser rather than air change rate.,
作者机构：
[Ding De-xin] Cent S Univ, Sch Resources & Safety Engn, Changsha 410083, Peoples R China.;Nanhua Univ, Sch Architectural Resources & Environm Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Ding De-xin] C;Cent S Univ, Sch Resources & Safety Engn, Changsha 410083, Peoples R China.
关键词：
mining induced surface subsidence;fuzziness and interaction of parameters;artificial neural fuzzy inference system
摘要：
There are many parameters influencing mining induced surface subsidence. These parameters usually interact with one another and some of them have the characteristic of fuzziness. Current approaches to predicting the subsidence cannot take into account of such interactions and fuzziness. In order to overcome this disadvantage, many mining induced surface subsidence cases were accumulated, and an artificial neuro fuzzy inference system(ANFIS) was used to set up 4 ANFIS models to predict the rise angle, dip angle, center angle and the maximum subsidence, respectively. The fitting and generalization prediction capabilities of the models were tested. The test results show that the models have very good fitting and generalization prediction capabilities and the approach can be applied to predict the mining induced surface subsidence.
摘要：
Current design method for circular sliding slopes is not so reasonable that it often results in slope sliding. As a result, artificial neural network (ANN) is used to establish an artificial neural network based inverse design method for circular sliding slopes. A sample set containing 21 successful circular sliding slopes excavated in the past is used to train the network. A test sample of 3 successful circular sliding slopes excavated in the past is used to test the trained network. The test results show that the ANN based inverse design method is valid and can be applied to the design of circular sliding slopes.
期刊：
Journal of Chemical Information and Modeling,2002年42(3):529-533 ISSN：1549-9596
通讯作者：
Liu, YC
作者机构：
[Liu, YC] Nanhua Univ, Inst Engn & Technol, Dept Math & Phys Sci, Hengyang 421001, Hunan, Peoples R China.;Xinjiang Univ, Inst Math & Phys, Urumqi 830046, Xinjiang, Peoples R China.;Huazhong Univ Sci & Technol, Dept Control Sci & Engn, Wuhan 430074, Hubei, Peoples R China.
通讯机构：
[Liu, YC] N;Nanhua Univ, Inst Engn & Technol, Dept Math & Phys Sci, Hengyang 421001, Hunan, Peoples R China.
摘要：
Some 2-D and 3-D graphical representations of DNA sequences have been given by Nandy, Leong and Mogenthaler, and Randic et al., which give visual characterizations of DNA sequences. In this paper, we presented a novel graphical representation of DNA sequences by taking four special vectors in 2-D Cartesian coordinate system to represent the four nucleic acid bases in DNA sequences, so that a DNA sequence is denoted on a plane by a directed walk. It is shown that the new graphical representation of DNA sequences has lower or nondegeneracy.
摘要：
With the increasing use of high-strength concrete (fc > 60 MPa) in building construction, the risk of exposing these structures to high temperatures during a fire has increased significantly. To be able to assess the structural safety of such structures after a fire, it is important that the mechanical properties of the material be well assessed with regard to high-temperature effects. In this context, a study was conducted to investigate the residual mechanical properties of confined and unconfined high-strength concrete (fc = 70 MPa) after a single thermal cycle at 100, 200, 300, 400, 500, 600, 700, 800, and 900°C. An analytical model for the stress-strain relationship for uniaxially loaded high-strength concrete was empirically developed and was shown to be applicable to confined and unconfined concrete after a cycle at a high temperature. The main parameters required to establish the stress-strain relationship are the peak stress, the elastic modulus, and the strain at peak stress. Empirical expressions for these parameters were developed to take into account the temperature and the level of confinement. The knowledge of the residual mechanical properties of concrete is necessary whenever the thermally damaged structure is required to bear a significant share of the loads, even after a severe thermal accident.
