文章就测量反应速率的3个实验，分别对人教版高中教材选修四《化学反应原理》和新加坡教材《Discover Chemis.try Normal 5N》两国教材中“化学反应速率实验”进行了比较和分析。通过实验试做，从两国实验的设计和实验分析比较，结果表...文章就测量反应速率的3个实验，分别对人教版高中教材选修四《化学反应原理》和新加坡教材《Discover Chemis.try Normal 5N》两国教材中“化学反应速率实验”进行了比较和分析。通过实验试做，从两国实验的设计和实验分析比较，结果表明：人教版“化学反应速率实验”倾向于浓度对化学反应速率的影响，注重实验和结论的分析；新加坡教材则更倾向通过实验培养学生的科学探究能力，分别用了测量某一生成物单位时间内体积的变化量和单位时间内质量的变化量来说明反应速率，给同学们提供了知识与技能提升的空间，满足了不同层次学生的需要。在教材实验的基础上，进行了分析和改进，为教学提供一定的借鉴作用。展开更多
提出了基于径向基(Radial Basis Function 简称 RBF)神经网络的动态误差模型的辨识方法。对如何从一般正交三轴转台速率实验获取训练样本及对网络的学习训练给予了详细的介绍。仿真结果证明了这个方法是可行有效的,可以提高光纤陀螺的...提出了基于径向基(Radial Basis Function 简称 RBF)神经网络的动态误差模型的辨识方法。对如何从一般正交三轴转台速率实验获取训练样本及对网络的学习训练给予了详细的介绍。仿真结果证明了这个方法是可行有效的,可以提高光纤陀螺的输出精度。展开更多
Short term uptake experiments and long term semicontinuous culture experiments were performed under the condition of phosphorus (P) limitation to estimate and compare the P uptake and growth kinetics of the microalga ...Short term uptake experiments and long term semicontinuous culture experiments were performed under the condition of phosphorus (P) limitation to estimate and compare the P uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa. Two new parameters, the maximum specific uptake rate ( V sp m) and the maximal growth efficiency ( β ), are introduced to achieve uniformity for the comparison of nutrient uptake and growth efficiency between microalgae and macroalgae. T. subcordiformis possesses 3 times lower half saturation uptake constant, 4 times higher maximal growth rate and 20 times higher maximum specific uptake rate than U. pertusa, while U. pertusa possesses 4 times higher maximal growth efficiency than T. subcordiformis.展开更多
A series of laboratory experiments and PFC numerical simulations for rock-like material specimens containing two unparallel fissures were carried out.On the basis of experimental and numerical results,the stress-strai...A series of laboratory experiments and PFC numerical simulations for rock-like material specimens containing two unparallel fissures were carried out.On the basis of experimental and numerical results,the stress-strain curves,mechanical properties,AE events,cracking behavior and energy characteristics were analyzed to reveal the macro-mechanical behavior and meso-mechanism of pre-fissured specimens under different loading rates.Investigated results show that:1)When the loading rate is relatively low,the stress-strain curves show a brittle response.When the loading rate is relatively high,the curve shows a more ductile response.Both of the peak strength and elastic mudulus increase with the increase of loading rate,which can be expressed as power functions.2)Four crack types are identified,i.e.,tensile crack,shear crack,far-field crack and surface spalling.Moreover,the tensile crack,far-field crack and surface spalling are under tensile mechanism,while the shear crack is under shear mechanism.3)The drops of the stress-strain curves all correspond to the crack initiation or coalescence,which is also linked to a sudden increasing in the accumulated micro-crack curve.4)Both of the maximum bond force and energy have the similar trend with the increase of loading rate to peak strength,which indicates that the trend of peak strength can be explained by the meso-mechanics and energy.展开更多
The corrosions resulting from defects in painting layers frequently occur in Al alloys, so the application of corrosion preventing systems is also very important. Optimum conditions in terms of electrochemistry in rel...The corrosions resulting from defects in painting layers frequently occur in Al alloys, so the application of corrosion preventing systems is also very important. Optimum conditions in terms of electrochemistry in relation to solution treatment, quenching and artificial aging treatment were established in order to optimize precipitation strengthening conditions intended to enhance the strength of Al alloys. Slow strain rate tests （SSRT） at various applied potentials were conducted in potential range from -1.8 to 0.5 V. The results show that the maximum tensile strengths, elongations and time-to-fracture are shown to be high values. After precipitation strengthening heat treatment, a tendency appear that time-to-fracture increases as elongation increases. In the potential range from -1.3 V to -0.7 V, the specimens show excellent mechanical properties, and thus this range is considered to be a corrosion prevention range.展开更多
An isothermal operation is implemented by employing a thermogravimetric analyzer (TGA) for simulating the thermal decomposition behavior of 58μm pine sawdust in air atmosphere.An independent parallel reaction model i...An isothermal operation is implemented by employing a thermogravimetric analyzer (TGA) for simulating the thermal decomposition behavior of 58μm pine sawdust in air atmosphere.An independent parallel reaction model is adopted in this study to describe the thermal decomposition mechanism.The Weibull distribution function is used to record and analyze the weight loss during isothermal decomposition at different temperatures(500,600,700,and 800°C).The total weight loss of the pine sawdust is assumed as a linear combination of individual weight loss from three components,including the char and two volatile matters.The plot of the thermal decomposition rate curve leads to kinetic parameters such as the reaction rate constants and the reaction order.The results show that the Weibull distribution function successfully represents decomposition curves of three components,and fits the experimental data very well.Therefore,this study provides a simple way to evaluate the decomposition rate of biomass combustion in a real combustor.展开更多
The green alga Tetraselmis subcordiformis has been widely used as a quality live food for aquaculture species, and also has been studied as a model organism for the photo-biological production of hydrogen. We attempte...The green alga Tetraselmis subcordiformis has been widely used as a quality live food for aquaculture species, and also has been studied as a model organism for the photo-biological production of hydrogen. We attempted to quantify the relationship between T. subcordiformis specific growth rate （SGR） and three important environmental factors （temperature, salinity, and pH） using the central composite design and response surface method under laboratory conditions. The results showed that the linear effects of temperature and salinity were significant （P〈0.05）, and they were equally important in impacting T. subcordiformis specific growth; the linear effect of pH was not significant （P〉0.05）; the interactive effect of temperature and pH was significant （P〈0.05）, whereas the temperature ~ salinity and salinity x pH interactions were not significant （P〉0.05）; all of the quadratic effects of the three factors were significant （P〈0.05）. A model equation for specific growth rate with the three factors was established, with the unadjusted and predictive R2 as high as 0.990 and 0.921, respectively, suggesting that the model was a very good fit and that it could be used to predict SGR. Through optimizing the reliable model, an optimal 3-factor combination of 25~C/35 of salinity/pH 7.9 was obtained, at which the maximum specific growth rate （0.65） was recorded, with a desirability value of 93.8%. These experimental results could serve as guidelines for increasing T. subcordiformis production efficiency.展开更多
The hot deformation behaviors of solution treated Mg-1.8Mn-0.4Er-0.2Al alloys were investigated by means of compression tests on Gleeble-1500 in strain rate range of 0.01-10s-1,deformation temperature range of 250-450...The hot deformation behaviors of solution treated Mg-1.8Mn-0.4Er-0.2Al alloys were investigated by means of compression tests on Gleeble-1500 in strain rate range of 0.01-10s-1,deformation temperature range of 250-450℃ and a true strain of 0.6.The constitutive relationships among flow stress,strain rate and deformation temperature were described by Arrhenius-type equations,based on the fact that the material constants could be calculated under a wide range of strains.The results show that the flow stress of the experimental alloy decreases with temperature increasing and strain rate decreasing.Under the experimental conditions,the products of constant α and n in the constitutive equation are stable within certain strains,and the deformation activation energy ranges from 160 to 220 kJ/mol.It is proved that the values of calculated flow stress are close to the experimental results with average error of 2.01%.展开更多
文摘文章就测量反应速率的3个实验，分别对人教版高中教材选修四《化学反应原理》和新加坡教材《Discover Chemis.try Normal 5N》两国教材中“化学反应速率实验”进行了比较和分析。通过实验试做，从两国实验的设计和实验分析比较，结果表明：人教版“化学反应速率实验”倾向于浓度对化学反应速率的影响，注重实验和结论的分析；新加坡教材则更倾向通过实验培养学生的科学探究能力，分别用了测量某一生成物单位时间内体积的变化量和单位时间内质量的变化量来说明反应速率，给同学们提供了知识与技能提升的空间，满足了不同层次学生的需要。在教材实验的基础上，进行了分析和改进，为教学提供一定的借鉴作用。
基金supported by the Project under Major State Basic Research of China(G1999012011).
文摘Short term uptake experiments and long term semicontinuous culture experiments were performed under the condition of phosphorus (P) limitation to estimate and compare the P uptake and growth kinetics of the microalga Tetraselmis subcordiformis and the macroalga Ulva pertusa. Two new parameters, the maximum specific uptake rate ( V sp m) and the maximal growth efficiency ( β ), are introduced to achieve uniformity for the comparison of nutrient uptake and growth efficiency between microalgae and macroalgae. T. subcordiformis possesses 3 times lower half saturation uptake constant, 4 times higher maximal growth rate and 20 times higher maximum specific uptake rate than U. pertusa, while U. pertusa possesses 4 times higher maximal growth efficiency than T. subcordiformis.
基金Project(BK20150005) supported by the Natural Science Foundation of Jiangsu Province for Distinguished Young Scholars,ChinaProject(2014YC10) supported by the Fundamental Research Funds for the Central Universities,China
文摘A series of laboratory experiments and PFC numerical simulations for rock-like material specimens containing two unparallel fissures were carried out.On the basis of experimental and numerical results,the stress-strain curves,mechanical properties,AE events,cracking behavior and energy characteristics were analyzed to reveal the macro-mechanical behavior and meso-mechanism of pre-fissured specimens under different loading rates.Investigated results show that:1)When the loading rate is relatively low,the stress-strain curves show a brittle response.When the loading rate is relatively high,the curve shows a more ductile response.Both of the peak strength and elastic mudulus increase with the increase of loading rate,which can be expressed as power functions.2)Four crack types are identified,i.e.,tensile crack,shear crack,far-field crack and surface spalling.Moreover,the tensile crack,far-field crack and surface spalling are under tensile mechanism,while the shear crack is under shear mechanism.3)The drops of the stress-strain curves all correspond to the crack initiation or coalescence,which is also linked to a sudden increasing in the accumulated micro-crack curve.4)Both of the maximum bond force and energy have the similar trend with the increase of loading rate to peak strength,which indicates that the trend of peak strength can be explained by the meso-mechanics and energy.
文摘The corrosions resulting from defects in painting layers frequently occur in Al alloys, so the application of corrosion preventing systems is also very important. Optimum conditions in terms of electrochemistry in relation to solution treatment, quenching and artificial aging treatment were established in order to optimize precipitation strengthening conditions intended to enhance the strength of Al alloys. Slow strain rate tests （SSRT） at various applied potentials were conducted in potential range from -1.8 to 0.5 V. The results show that the maximum tensile strengths, elongations and time-to-fracture are shown to be high values. After precipitation strengthening heat treatment, a tendency appear that time-to-fracture increases as elongation increases. In the potential range from -1.3 V to -0.7 V, the specimens show excellent mechanical properties, and thus this range is considered to be a corrosion prevention range.
基金Supported by the Chung Yuan Christian University (CYCU-97-CR-CE)
文摘An isothermal operation is implemented by employing a thermogravimetric analyzer (TGA) for simulating the thermal decomposition behavior of 58μm pine sawdust in air atmosphere.An independent parallel reaction model is adopted in this study to describe the thermal decomposition mechanism.The Weibull distribution function is used to record and analyze the weight loss during isothermal decomposition at different temperatures(500,600,700,and 800°C).The total weight loss of the pine sawdust is assumed as a linear combination of individual weight loss from three components,including the char and two volatile matters.The plot of the thermal decomposition rate curve leads to kinetic parameters such as the reaction rate constants and the reaction order.The results show that the Weibull distribution function successfully represents decomposition curves of three components,and fits the experimental data very well.Therefore,this study provides a simple way to evaluate the decomposition rate of biomass combustion in a real combustor.
基金Supported by the Guangdong Province Science and Technology Project(No.2010B020201014)the Guangdong Province South China Sea Invertebrates Healthy Culture Engineering Technology Research Center(No.GCZX-A0909)+2 种基金the Guangdong Province Ocean and Fisheries Science and Technology Extension Project(No.20120980)the Guangdong Province Industry-University-Science Partnership Project(No.20110908)the Sci&Tech Plan of Huaiyin Normal University(No.WH0031)
文摘The green alga Tetraselmis subcordiformis has been widely used as a quality live food for aquaculture species, and also has been studied as a model organism for the photo-biological production of hydrogen. We attempted to quantify the relationship between T. subcordiformis specific growth rate （SGR） and three important environmental factors （temperature, salinity, and pH） using the central composite design and response surface method under laboratory conditions. The results showed that the linear effects of temperature and salinity were significant （P〈0.05）, and they were equally important in impacting T. subcordiformis specific growth; the linear effect of pH was not significant （P〉0.05）; the interactive effect of temperature and pH was significant （P〈0.05）, whereas the temperature ~ salinity and salinity x pH interactions were not significant （P〉0.05）; all of the quadratic effects of the three factors were significant （P〈0.05）. A model equation for specific growth rate with the three factors was established, with the unadjusted and predictive R2 as high as 0.990 and 0.921, respectively, suggesting that the model was a very good fit and that it could be used to predict SGR. Through optimizing the reliable model, an optimal 3-factor combination of 25~C/35 of salinity/pH 7.9 was obtained, at which the maximum specific growth rate （0.65） was recorded, with a desirability value of 93.8%. These experimental results could serve as guidelines for increasing T. subcordiformis production efficiency.
基金Project(2008BA4036) supported by the Natural Science Foundation of Chongqing Science and Technology Commission, ChinaProject(081061130) supported by the National University Students Research Training Program and Sharing Fund of Chongqing University’s Large-scale Equipment
文摘The hot deformation behaviors of solution treated Mg-1.8Mn-0.4Er-0.2Al alloys were investigated by means of compression tests on Gleeble-1500 in strain rate range of 0.01-10s-1,deformation temperature range of 250-450℃ and a true strain of 0.6.The constitutive relationships among flow stress,strain rate and deformation temperature were described by Arrhenius-type equations,based on the fact that the material constants could be calculated under a wide range of strains.The results show that the flow stress of the experimental alloy decreases with temperature increasing and strain rate decreasing.Under the experimental conditions,the products of constant α and n in the constitutive equation are stable within certain strains,and the deformation activation energy ranges from 160 to 220 kJ/mol.It is proved that the values of calculated flow stress are close to the experimental results with average error of 2.01%.
