Progress in hydrate thermodynamic study necessitates robust and fast models to be incorporated in reservoir simulation softwares. However, numerous models presented in the literature makes selection of the best,proper...Progress in hydrate thermodynamic study necessitates robust and fast models to be incorporated in reservoir simulation softwares. However, numerous models presented in the literature makes selection of the best,proper predictive model a cumbersome task. It is of industrial interest to make use of cubic equations of state(EOS) for modeling hydrate equilibria. In this regard, this study focuses on evaluation of three common EOSs including Peng–Robinson, Soave–Redlich–Kwong and Valderrama–Patel–Teja coupled with van der Waals and Platteeuw theory to predict hydrate P–T equilibrium of a real natural gas sample. Each EOS was accompanied with three mixing rules, including van der Waals(vd W),Avlonitis non-density dependent(ANDD) and general nonquadratic(GNQ). The prediction of cubic EOSs was in sufficient agreement with experimental data and with overall AARD% of less than unity. In addition, PR plus ANDD proved to be the most accurate model in this study for prediction of hydrate equilibria with AARD% of 0.166.It was observed that the accuracy of cubic EOSs studied in this paper depends on mixing rule coupled with them,especially at high-pressure conditions. Lastly, the present study does not include any adjustable parameter to be correlated with hydrate phase equilibrium data.展开更多
The original version of this article unfortunately contained one mistake.The institutions of the authors are wrong.The corrected institutions are given below.
BACKGROUND ： Parkinson disease is neurodegenerative disorders, characterized by a progressive and selective degeneration of nigrostdatal dopaminergic pathway. Its main clinical symptoms include bradykinesia, dgidity,...BACKGROUND ： Parkinson disease is neurodegenerative disorders, characterized by a progressive and selective degeneration of nigrostdatal dopaminergic pathway. Its main clinical symptoms include bradykinesia, dgidity, rest tremor and disturbances in balance. Levodopa （L-DOPA） is the ＂gold standard＂ for the symptomatic treatment of Parkinson disease, but L-DOPA is toxic to dopaminergic neurons and the chronic administration of L-DOPA often causes the side effects of motor such as ＂on-off ＂, etc., and its mechanism still has not been completely clarified. OBJECTIVE ： To observe the changes of the content of glutathione （GSH）, activities of glutathione peroxidase （GSH-Px） and superoxide dismutase （SOD） and content of malondialdehyde （MDA） in gila-containing mesencephalic culture fluid after L-DOPA of different concentrations were added. DESIGN： A comparative observation. SETTINGS ： Department of Neurology, Affiliated Hospital of Taishan Medical University; Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology. MATERIALS ： The experiment was carried out in the Basic Research Institute, Taishan Medical University from December 2003 to September 2004. Ten postnatal newborn SD rats （within 2 days） were selected, either male or female. Fetal bovine serum （DMEM/F12） was from Gibco Company; L-DOPA and glial fibrillary acidic protein （GFAP） from Sigma Company. Kits for determination of GSH, GSH-Px, SOD and MDA were purchased from Nanjing Jiancheng Bioengineering Research Institute. METHODS ： Gila-containing mesencephalic culture fluid were placed in 24-well culture plate, and L-DOPA of 50, 100 and 500 μmot/L was added to each group, the blank control group was also set. The glia-containing mesencephalic culture fluid selected at 4, 24, 48 and 72 hours respectively to determine the GSH content with colorimetdc quantitative technique, GSH-Px activity with colorimetdc method, SOD activity with xanthine oxidase method and MDA content with thiol-barbituric acid method. MAIN OUTCOME MEASURES ： GSH and MDA contents, GSH-Px and SOD activities in the glia-containing mesencephalic culture fluid at 4, 24, 48 and 72 hours after L-DOPA of different concentrations were added. RESULTS ： In the glia-containing mesencephalic culture fluid after 100 μmol/L L-DOPA was added for 24, 48 and 72 hours, the GSH contents were lower than those in the blank control group [（174.14±39.28）, （161.55± 40.79）, （144.97±57.59） mg/L; （220.66±32.61）, （221.10±32.98）, （220.43±31.98） mg/L, P 〈 0.05]; The GSH-Px activities were lower than those in the blank control group [（4.03±1.05）, （3.99±1.12）, （3.47±1.00） μmol/L; （5.45±1.14）, （5.69±1.21）, （5.49±1.28） μmol/L, P 〈 0.05]; The SOD activities were also lower than those in the blank control group [（42.02±5.08）, （39.38±5.34）, （38.87±5.75）kNU/L; （51.35±8.87）, （51.78±8.96）, （50.99± 9.09） kNU/L, P 〈 0.05]; Whereas the MDA contents were higher than those in the blank control group [（3.51 ± 1.05）, （3.99±1.03）, （4.45±1.58） μmol/L; （2.09±1.13）, （2.18±1.29）, （2.01±1.05） μmol/L, P〈 0.05]. In the gli- a-containing mesencephalic culture fluid after 100 μmol/L L-DOPA was added for 4, 24, 48 and 72 hours, the GSH contents were （172.27±26.07）, （140.15±61.44）, （137.30±50.87）, （121.09±66.07） mg/L, the GSH-Px activities were （3.89±1.20）, （3.56±1.23）, （3.38±1.18）, （3.01±1.09） μmol/L, the SOD activities were （38.18±6.75）, （35.23±7.85）, （4.59±1.24）, （31.42±7.01） kNU/L, which were all lower than those in the blank control group （P 〈 0.05-0.01 ）; The MDA contents were （3.65±0.86）, （3.87±1.14）, （4.59±1.24）, （4.79±1.32） μmol/L, which were higher than those in the blank control group （P 〈 0.05-0.01）. In the gila-containing mesencephalic culture fluid added by 50 μmol/L L-DOPA, the GSH and MDA contents, GSH-Px and SOD activities at each time point were all close to those in the blank control group （P〉 0.05）. CONCLUSION ： L-DOPA of certain concentration can destroy the dynamical balance of free radicals in glia-containing mesencephalic culture fluid, and accelerate the degeneration of neurons, which are in concentration- and time-dependent manners.展开更多
A hyperchaos-based watermarking algorithm is developed in the wavelet domain for images.The algorithm is based on discrete wavelet transform and combines the communication model with side information.We utilize a suit...A hyperchaos-based watermarking algorithm is developed in the wavelet domain for images.The algorithm is based on discrete wavelet transform and combines the communication model with side information.We utilize a suitable scale factor to scale host image,then construct cosets for embedding digital watermarking according to scale version of the host image.Our scheme makes a tradeoff between imperceptibility and robustness,and achieves security.The extraction algorithm is a blind detection algorithm which retrieves the watermark without the original host image.In addition,we propose a new method for watermark encryption with hyperchaotic sequence.This method overcomes the drawback of small key space of chaotic sequence and improves the watermark security.Simulation results indicate that the algorithm is a well-balanced watermarking method that offers good robustness and imperceptibility.展开更多
This paper addresses the use of fuzzy neural networks （FNN） for predicting the nonlinear network traffic. Through training the fuzzy neural networks with momentum back-propagation algorithm （MOBP） and choosing the...This paper addresses the use of fuzzy neural networks （FNN） for predicting the nonlinear network traffic. Through training the fuzzy neural networks with momentum back-propagation algorithm （MOBP） and choosing the appropriate activation function of output node, the traffic series can be well predicted by these structures. From the effective forecasting results obtained, it can be concluded that fuzzy neural networks can be well applicable for the traffic series prediction. In addition,the performance of the FNN was particularly discussed and analyzed in terms of prediction ability compared with solely neural networks. The effectiveness of the oroBosecl FNN is demonstrated through the simulation.展开更多
The field emission characteristics of multiwalled carbon nanotubes grown on metal tips are studied at various temperatures. It is found that emission current at a given applied electric field increased with the temper...The field emission characteristics of multiwalled carbon nanotubes grown on metal tips are studied at various temperatures. It is found that emission current at a given applied electric field increased with the temperature, and the stability of the current did not change. The dependence upon temperature varies quite differently with the metal substrates. This may result from the asymmetry of the CNTs and the interface effect between CNT and underlay.展开更多
We investigate the performance of a novel vertical slot fishway by employing finite volume and surrogate models.Multiple linear regression,multiple log equation regression,gene expression programming,and combinations ...We investigate the performance of a novel vertical slot fishway by employing finite volume and surrogate models.Multiple linear regression,multiple log equation regression,gene expression programming,and combinations of these models are employed to predict the maximum turbulence,maximum velocity,resting area,and water depth of the middle pool in the fishway.The statistical parameters and error terms,including the coefficient of determination,root mean square error,normalized square error,maximum positive and negative errors,and mean absolute percentage error were employed to evaluate and compare the accuracy of the models.We also conducted a parametric study.The independent variables include the opening between bafles(OBB),the ratio of the length of the large and small baffles,the volume flow rate,and the angle of the large baffle.The results show that the key parameters of the maximum turbulence and velocity are the volume flow rate and OBB.展开更多
The LHAASO-WFCTA experiment,which aims to observe cosmic rays in the sub-EeV range using the fluorescence technique,uses a new generation of high-performance telescopes.To ensure that the experiment has ex-cellent det...The LHAASO-WFCTA experiment,which aims to observe cosmic rays in the sub-EeV range using the fluorescence technique,uses a new generation of high-performance telescopes.To ensure that the experiment has ex-cellent detection capability associated with the measurement of the energy spectrum,the primary composition of cosmic rays,and so on,an accurate geometrical reconstruction of air-shower events is fundamental.This paper de-scribes the development and testing of geometrical reconstruction for stereo viewed events using the WFCTA(Wide Field of view Cherenkov/Fluorescence Telescope Array)detectors.Two approaches,which take full advantage ofthe WFCTA detectors.are investigated.One is the stereo-angular method,which uses the pointing of triggered SiPMs in the shower trajectory,and the other is the stereo-timing method,which uses the triggering time of the fired SiPMs.The results show that both methods have good geometrical resolution:the resolution of the stereo-timing method is slightly better than the stereo-angular method because the resolution of the latter is slightly limited by the shower track length.展开更多
文摘Progress in hydrate thermodynamic study necessitates robust and fast models to be incorporated in reservoir simulation softwares. However, numerous models presented in the literature makes selection of the best,proper predictive model a cumbersome task. It is of industrial interest to make use of cubic equations of state(EOS) for modeling hydrate equilibria. In this regard, this study focuses on evaluation of three common EOSs including Peng–Robinson, Soave–Redlich–Kwong and Valderrama–Patel–Teja coupled with van der Waals and Platteeuw theory to predict hydrate P–T equilibrium of a real natural gas sample. Each EOS was accompanied with three mixing rules, including van der Waals(vd W),Avlonitis non-density dependent(ANDD) and general nonquadratic(GNQ). The prediction of cubic EOSs was in sufficient agreement with experimental data and with overall AARD% of less than unity. In addition, PR plus ANDD proved to be the most accurate model in this study for prediction of hydrate equilibria with AARD% of 0.166.It was observed that the accuracy of cubic EOSs studied in this paper depends on mixing rule coupled with them,especially at high-pressure conditions. Lastly, the present study does not include any adjustable parameter to be correlated with hydrate phase equilibrium data.
文摘The original version of this article unfortunately contained one mistake.The institutions of the authors are wrong.The corrected institutions are given below.
文摘BACKGROUND ： Parkinson disease is neurodegenerative disorders, characterized by a progressive and selective degeneration of nigrostdatal dopaminergic pathway. Its main clinical symptoms include bradykinesia, dgidity, rest tremor and disturbances in balance. Levodopa （L-DOPA） is the ＂gold standard＂ for the symptomatic treatment of Parkinson disease, but L-DOPA is toxic to dopaminergic neurons and the chronic administration of L-DOPA often causes the side effects of motor such as ＂on-off ＂, etc., and its mechanism still has not been completely clarified. OBJECTIVE ： To observe the changes of the content of glutathione （GSH）, activities of glutathione peroxidase （GSH-Px） and superoxide dismutase （SOD） and content of malondialdehyde （MDA） in gila-containing mesencephalic culture fluid after L-DOPA of different concentrations were added. DESIGN： A comparative observation. SETTINGS ： Department of Neurology, Affiliated Hospital of Taishan Medical University; Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology. MATERIALS ： The experiment was carried out in the Basic Research Institute, Taishan Medical University from December 2003 to September 2004. Ten postnatal newborn SD rats （within 2 days） were selected, either male or female. Fetal bovine serum （DMEM/F12） was from Gibco Company; L-DOPA and glial fibrillary acidic protein （GFAP） from Sigma Company. Kits for determination of GSH, GSH-Px, SOD and MDA were purchased from Nanjing Jiancheng Bioengineering Research Institute. METHODS ： Gila-containing mesencephalic culture fluid were placed in 24-well culture plate, and L-DOPA of 50, 100 and 500 μmot/L was added to each group, the blank control group was also set. The glia-containing mesencephalic culture fluid selected at 4, 24, 48 and 72 hours respectively to determine the GSH content with colorimetdc quantitative technique, GSH-Px activity with colorimetdc method, SOD activity with xanthine oxidase method and MDA content with thiol-barbituric acid method. MAIN OUTCOME MEASURES ： GSH and MDA contents, GSH-Px and SOD activities in the glia-containing mesencephalic culture fluid at 4, 24, 48 and 72 hours after L-DOPA of different concentrations were added. RESULTS ： In the glia-containing mesencephalic culture fluid after 100 μmol/L L-DOPA was added for 24, 48 and 72 hours, the GSH contents were lower than those in the blank control group [（174.14±39.28）, （161.55± 40.79）, （144.97±57.59） mg/L; （220.66±32.61）, （221.10±32.98）, （220.43±31.98） mg/L, P 〈 0.05]; The GSH-Px activities were lower than those in the blank control group [（4.03±1.05）, （3.99±1.12）, （3.47±1.00） μmol/L; （5.45±1.14）, （5.69±1.21）, （5.49±1.28） μmol/L, P 〈 0.05]; The SOD activities were also lower than those in the blank control group [（42.02±5.08）, （39.38±5.34）, （38.87±5.75）kNU/L; （51.35±8.87）, （51.78±8.96）, （50.99± 9.09） kNU/L, P 〈 0.05]; Whereas the MDA contents were higher than those in the blank control group [（3.51 ± 1.05）, （3.99±1.03）, （4.45±1.58） μmol/L; （2.09±1.13）, （2.18±1.29）, （2.01±1.05） μmol/L, P〈 0.05]. In the gli- a-containing mesencephalic culture fluid after 100 μmol/L L-DOPA was added for 4, 24, 48 and 72 hours, the GSH contents were （172.27±26.07）, （140.15±61.44）, （137.30±50.87）, （121.09±66.07） mg/L, the GSH-Px activities were （3.89±1.20）, （3.56±1.23）, （3.38±1.18）, （3.01±1.09） μmol/L, the SOD activities were （38.18±6.75）, （35.23±7.85）, （4.59±1.24）, （31.42±7.01） kNU/L, which were all lower than those in the blank control group （P 〈 0.05-0.01 ）; The MDA contents were （3.65±0.86）, （3.87±1.14）, （4.59±1.24）, （4.79±1.32） μmol/L, which were higher than those in the blank control group （P 〈 0.05-0.01）. In the gila-containing mesencephalic culture fluid added by 50 μmol/L L-DOPA, the GSH and MDA contents, GSH-Px and SOD activities at each time point were all close to those in the blank control group （P〉 0.05）. CONCLUSION ： L-DOPA of certain concentration can destroy the dynamical balance of free radicals in glia-containing mesencephalic culture fluid, and accelerate the degeneration of neurons, which are in concentration- and time-dependent manners.
基金Supported by National Natural Science Foundation of China(60574036) ,the Specialized Research Fund for the Doctoral Pro-gramof Higher Education of China (20050055013) ,and the program for New Century Excellent Talents in University of China(NCET) .
文摘A hyperchaos-based watermarking algorithm is developed in the wavelet domain for images.The algorithm is based on discrete wavelet transform and combines the communication model with side information.We utilize a suitable scale factor to scale host image,then construct cosets for embedding digital watermarking according to scale version of the host image.Our scheme makes a tradeoff between imperceptibility and robustness,and achieves security.The extraction algorithm is a blind detection algorithm which retrieves the watermark without the original host image.In addition,we propose a new method for watermark encryption with hyperchaotic sequence.This method overcomes the drawback of small key space of chaotic sequence and improves the watermark security.Simulation results indicate that the algorithm is a well-balanced watermarking method that offers good robustness and imperceptibility.
基金This workis supportedin part by China Postdoctoral Foundationunder grant (2005037529) ,Tianjin High Education Science De-velopment Foundation under grant (20041325) and Education Ministry Doctoral Discipline Foundation of China under grant(2003005607) .
文摘This paper addresses the use of fuzzy neural networks （FNN） for predicting the nonlinear network traffic. Through training the fuzzy neural networks with momentum back-propagation algorithm （MOBP） and choosing the appropriate activation function of output node, the traffic series can be well predicted by these structures. From the effective forecasting results obtained, it can be concluded that fuzzy neural networks can be well applicable for the traffic series prediction. In addition,the performance of the FNN was particularly discussed and analyzed in terms of prediction ability compared with solely neural networks. The effectiveness of the oroBosecl FNN is demonstrated through the simulation.
基金the 973 Program of the Ministry of Science and Technology of China (Grant No. 2003CB314702)
文摘The field emission characteristics of multiwalled carbon nanotubes grown on metal tips are studied at various temperatures. It is found that emission current at a given applied electric field increased with the temperature, and the stability of the current did not change. The dependence upon temperature varies quite differently with the metal substrates. This may result from the asymmetry of the CNTs and the interface effect between CNT and underlay.
文摘We investigate the performance of a novel vertical slot fishway by employing finite volume and surrogate models.Multiple linear regression,multiple log equation regression,gene expression programming,and combinations of these models are employed to predict the maximum turbulence,maximum velocity,resting area,and water depth of the middle pool in the fishway.The statistical parameters and error terms,including the coefficient of determination,root mean square error,normalized square error,maximum positive and negative errors,and mean absolute percentage error were employed to evaluate and compare the accuracy of the models.We also conducted a parametric study.The independent variables include the opening between bafles(OBB),the ratio of the length of the large and small baffles,the volume flow rate,and the angle of the large baffle.The results show that the key parameters of the maximum turbulence and velocity are the volume flow rate and OBB.
基金National Natural Science Foundation of China(11903005,11563004,11475190)。
文摘The LHAASO-WFCTA experiment,which aims to observe cosmic rays in the sub-EeV range using the fluorescence technique,uses a new generation of high-performance telescopes.To ensure that the experiment has ex-cellent detection capability associated with the measurement of the energy spectrum,the primary composition of cosmic rays,and so on,an accurate geometrical reconstruction of air-shower events is fundamental.This paper de-scribes the development and testing of geometrical reconstruction for stereo viewed events using the WFCTA(Wide Field of view Cherenkov/Fluorescence Telescope Array)detectors.Two approaches,which take full advantage ofthe WFCTA detectors.are investigated.One is the stereo-angular method,which uses the pointing of triggered SiPMs in the shower trajectory,and the other is the stereo-timing method,which uses the triggering time of the fired SiPMs.The results show that both methods have good geometrical resolution:the resolution of the stereo-timing method is slightly better than the stereo-angular method because the resolution of the latter is slightly limited by the shower track length.
