Nature is amazing!Sometimes you don’t need a weather App to predict rain or shine-you just need nature!Feel the heat:listen to crickets Want to know the outside temperature?Listen to the crickets!Count how many times...Nature is amazing!Sometimes you don’t need a weather App to predict rain or shine-you just need nature!Feel the heat:listen to crickets Want to know the outside temperature?Listen to the crickets!Count how many times a cricket chirps in 15 seconds and add 40.That’s the temperature in Fahrenheit(华氏温度,1℉≈0.56℃).Do it several times and find the average.展开更多
This thesis sets out to classify the fossilized errors made by the subjects from lexical and syntactic levels respectively,through the empirical experiment and questionnaire.
This study investigates the droplet formation for the liquid–liquid two-phase flow within a square T-junction microchannel through numerical simulation using volume of fluid method and experimental visualization usin...This study investigates the droplet formation for the liquid–liquid two-phase flow within a square T-junction microchannel through numerical simulation using volume of fluid method and experimental visualization using high-speed camera imaging.The T-junction microchannel has a cross-sectional width of 0.6 mm and a total length of 27.3 mm.The solution of cyclohexane with 2%and 3%mass concentrations of sorbitan trioleate surfactant were used as the continuous phase,and water was used as the dispersed phase.Slug flow,characteristic of squeezing regime,were predominantly observed.The effects of liquid–liquid two-phase flow rate ratio,and dimensionless number on droplet size,and pressure drop were investigated.The squeezing regime was mapped for 0.0005≤Ca_(c)≤0.0052(capillary number)and 0.1≤q≤10(flow rate ratio).The pressure drops of slugs were in the range from 40 Pa to 200 Pa.The slug lengths were measured between 1 mm and 9 mm.A universal flow map dependent on Ca_(c)Re_(d)^(0.5) are projected to investigate the droplet formation behavior in T-junction microchannel.Correlation expressions are proposed to predict pressure drops and the slug lengths for liquid–liquid two-phase flow in a square T-junction microchannel,using dimensionless numbers such as flow rate ratio and capillary number.The result shows that large continuous phase flow rates facilitate smaller slugs,whereas higher dispersed phase flow rates result in longer shorts.展开更多
Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electro...Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann (LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas-liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined.展开更多
AIM： To investigate the independent factors associated with photic phenomena in patients implanted with refractive,rotationally asymmetric,multifocal intraocular lenses（MIOLs）.METHODS： Thirty-four eyes of 34 patie...AIM： To investigate the independent factors associated with photic phenomena in patients implanted with refractive,rotationally asymmetric,multifocal intraocular lenses（MIOLs）.METHODS： Thirty-four eyes of 34 patients who underwent unilateral cataract surgery,followed by implantation of rotationally asymmetric MIOLs were included.Distance and near visual acuity outcomes,intraocular aberrations,preferred reading distances,preoperative and postoperative refractive errors,mesopic and photopic pupil diameters,and the mesopic and photopic kappa angles were assessed.Patients were also administered a satisfaction survey.Photic phenomena were graded by questionnaire.Independent-related factors were identified by correlation and bivariate logistic regression analyses.RESULTS： The distance from the photopic to the mesopic pupil center（pupil center shift） was significantly associated with glare/halo symptoms [odds ratio（OR）=2.065,95% confidence interval（CI）=0.916-4.679,P=0.006] and night vision problems（OR=1.832,95% CI=0.721-2.158,P=0.007）.The preoperative photopic angle kappa was significantly associated with glare/halo symptoms（OR=2.155,95% CI=1.065-4.362,P=0.041）.The photopic angle kappa was also significantly associated with glare/halo symptoms（OR=2.155,95% CI=1.065-4.362,P=0.041） and with night vision problems（OR=1.832,95% CI=0.721-2.158,P=0.007） in patients implanted with rotationally asymmetric MIOLs.CONCLUSION： A large pupil center shift and misalignment between the visual and pupillary axis（angle kappa）may play a role in the occurrence of photic phenomena after implantation of rotationally asymmetric MIOLs.展开更多
A water model with a geometric similarity ratio of 1：5 was developed to investigate the gas-liquid mass transfer and flow charac- teristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a...A water model with a geometric similarity ratio of 1：5 was developed to investigate the gas-liquid mass transfer and flow charac- teristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a NaOH solution bath. The flow field, volumetric mass transfer coefficient per unit volume （Ak/V; where A is the contact area between phases, V is the volume, and k is the mass transfer coeffi- cient）, and gas utilization ratio （t/） were then measured at different gas flow rates and blow angles. The results showed that the flow field could be divided into five regions, i.e., injection, strong loop, weak loop, splashing, and dead zone. Whereas the Ak/V of the bath increased and then decreased with increasing gas flow rate, and n steadily increased. When the converter was rotated clockwise, both Ak/F and t/increased. However, the flow condition deteriorated when the gas flow rate and blow angle were drastically increased. Therefore, these para- meters must be controlled to optimal conditions. In the proposed model, the optimal gas flow rate and blow angle were 7.5 m3.h-1 and 10°, respectively.展开更多
In this article, we consider a two-component nonlinear shallow water system, which includes the famous 2-component Camassa-Holm and Degasperis-Procesi equations as special cases. The local well-posedess for this equat...In this article, we consider a two-component nonlinear shallow water system, which includes the famous 2-component Camassa-Holm and Degasperis-Procesi equations as special cases. The local well-posedess for this equations is established. Some sufficient conditions for blow-up of the solutions in finite time are given. Moreover, by separation method, the self-similar solutions for the nonlinear shallow water equations are obtained, and which local or global behavior can be determined by the corresponding Emden equation.展开更多
To enhance the quality of grade 20 carbon-steel on the continuous casting production line, the mechanism of forming blowholes and non-metallic inclusions in billets and numerical simulation of flow phenomena about liq...To enhance the quality of grade 20 carbon-steel on the continuous casting production line, the mechanism of forming blowholes and non-metallic inclusions in billets and numerical simulation of flow phenomena about liquid steel in tundish were studied. The results show that the configuration and operation of tundish play an important part in quality assurance of grade 20 carbon-steel products. By optimizing the configuration of the tundish, the depth of liquid bath in tundish is enhanced, the impact of liquid steel is decreased, and the residence time of liquid steel is lengthened, which is useful for eliminating inclusions and blowholes and improving the service life of tundish. Improving the pouring and tapping operation of liquid steel can avoid the contact of liquid steel with air, and decrease re-oxidation. Strict control of the superheat degree of casting liquid steel can decrease the non-metallic inclusion content of the re-oxidation in billets and reduce the erosion of tundish. The inclusions and blowholes in the continuous casting grade 20 steel billets are reduced to a great extent and qualification rate is enhanced from 60% to 80%.展开更多
Ionograms, which were obtained from February 1995 to January 1999 by a Digisonde Portable Sounder-4 (DPS-4) at Zhongshan Station in Antarctica, have been scaled. The ionograms interpretation has shown various ionosphc...Ionograms, which were obtained from February 1995 to January 1999 by a Digisonde Portable Sounder-4 (DPS-4) at Zhongshan Station in Antarctica, have been scaled. The ionograms interpretation has shown various ionosphcric phcnomena occurred in the cusp region. They are particle precipitation effects in the E region. F region magnetic noon phenomena, slant Es phenomena and lacuna. F layer irregularity zone (FLIZ) phenomena, and auroral oval identification. Typical examples of ionograms and ionogram sequences observed at Zhongshan Station are displayed in this paper.展开更多
文摘Nature is amazing!Sometimes you don’t need a weather App to predict rain or shine-you just need nature!Feel the heat:listen to crickets Want to know the outside temperature?Listen to the crickets!Count how many times a cricket chirps in 15 seconds and add 40.That’s the temperature in Fahrenheit(华氏温度,1℉≈0.56℃).Do it several times and find the average.
文摘This thesis sets out to classify the fossilized errors made by the subjects from lexical and syntactic levels respectively,through the empirical experiment and questionnaire.
基金supports for this project from the National Natural Science Foundation of China(22378295).
文摘This study investigates the droplet formation for the liquid–liquid two-phase flow within a square T-junction microchannel through numerical simulation using volume of fluid method and experimental visualization using high-speed camera imaging.The T-junction microchannel has a cross-sectional width of 0.6 mm and a total length of 27.3 mm.The solution of cyclohexane with 2%and 3%mass concentrations of sorbitan trioleate surfactant were used as the continuous phase,and water was used as the dispersed phase.Slug flow,characteristic of squeezing regime,were predominantly observed.The effects of liquid–liquid two-phase flow rate ratio,and dimensionless number on droplet size,and pressure drop were investigated.The squeezing regime was mapped for 0.0005≤Ca_(c)≤0.0052(capillary number)and 0.1≤q≤10(flow rate ratio).The pressure drops of slugs were in the range from 40 Pa to 200 Pa.The slug lengths were measured between 1 mm and 9 mm.A universal flow map dependent on Ca_(c)Re_(d)^(0.5) are projected to investigate the droplet formation behavior in T-junction microchannel.Correlation expressions are proposed to predict pressure drops and the slug lengths for liquid–liquid two-phase flow in a square T-junction microchannel,using dimensionless numbers such as flow rate ratio and capillary number.The result shows that large continuous phase flow rates facilitate smaller slugs,whereas higher dispersed phase flow rates result in longer shorts.
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region, China (Grant 623313)
文摘Fuel cells and flow batteries are promising technologies to address climate change and air pollution problems. An understanding of the complex multiscale and multiphysics transport phenomena occurring in these electrochemical systems requires powerful numerical tools. Over the past decades, the lattice Boltzmann (LB) method has attracted broad interest in the computational fluid dynamics and the numerical heat transfer communities, primarily due to its kinetic nature making it appropriate for modeling complex multiphase transport phenomena. More importantly, the LB method fits well with parallel computing due to its locality feature, which is required for large-scale engineering applications. In this article, we review the LB method for gas-liquid two-phase flows, coupled fluid flow and mass transport in porous media, and particulate flows. Examples of applications are provided in fuel cells and flow batteries. Further developments of the LB method are also outlined.
文摘AIM： To investigate the independent factors associated with photic phenomena in patients implanted with refractive,rotationally asymmetric,multifocal intraocular lenses（MIOLs）.METHODS： Thirty-four eyes of 34 patients who underwent unilateral cataract surgery,followed by implantation of rotationally asymmetric MIOLs were included.Distance and near visual acuity outcomes,intraocular aberrations,preferred reading distances,preoperative and postoperative refractive errors,mesopic and photopic pupil diameters,and the mesopic and photopic kappa angles were assessed.Patients were also administered a satisfaction survey.Photic phenomena were graded by questionnaire.Independent-related factors were identified by correlation and bivariate logistic regression analyses.RESULTS： The distance from the photopic to the mesopic pupil center（pupil center shift） was significantly associated with glare/halo symptoms [odds ratio（OR）=2.065,95% confidence interval（CI）=0.916-4.679,P=0.006] and night vision problems（OR=1.832,95% CI=0.721-2.158,P=0.007）.The preoperative photopic angle kappa was significantly associated with glare/halo symptoms（OR=2.155,95% CI=1.065-4.362,P=0.041）.The photopic angle kappa was also significantly associated with glare/halo symptoms（OR=2.155,95% CI=1.065-4.362,P=0.041） and with night vision problems（OR=1.832,95% CI=0.721-2.158,P=0.007） in patients implanted with rotationally asymmetric MIOLs.CONCLUSION： A large pupil center shift and misalignment between the visual and pupillary axis（angle kappa）may play a role in the occurrence of photic phenomena after implantation of rotationally asymmetric MIOLs.
基金financially supported by the National Natural Science Foundation of China(No.51504018)the China Postdoctoral Science Foundation(2015M580986)the Fundamental Research Funds for the Central Universities(FRF-TP-17-038A2)
文摘A water model with a geometric similarity ratio of 1：5 was developed to investigate the gas-liquid mass transfer and flow charac- teristics in a Peirce-Smith converter. A gas mixture of CO2 and Ar was injected into a NaOH solution bath. The flow field, volumetric mass transfer coefficient per unit volume （Ak/V; where A is the contact area between phases, V is the volume, and k is the mass transfer coeffi- cient）, and gas utilization ratio （t/） were then measured at different gas flow rates and blow angles. The results showed that the flow field could be divided into five regions, i.e., injection, strong loop, weak loop, splashing, and dead zone. Whereas the Ak/V of the bath increased and then decreased with increasing gas flow rate, and n steadily increased. When the converter was rotated clockwise, both Ak/F and t/increased. However, the flow condition deteriorated when the gas flow rate and blow angle were drastically increased. Therefore, these para- meters must be controlled to optimal conditions. In the proposed model, the optimal gas flow rate and blow angle were 7.5 m3.h-1 and 10°, respectively.
基金supported by NSF of China (11071266)partially supported by Scholarship Award for Excellent Doctoral Student granted by Ministry of Educationpartially supported by the found of Chongqing Normal University (13XLB006)
文摘In this article, we consider a two-component nonlinear shallow water system, which includes the famous 2-component Camassa-Holm and Degasperis-Procesi equations as special cases. The local well-posedess for this equations is established. Some sufficient conditions for blow-up of the solutions in finite time are given. Moreover, by separation method, the self-similar solutions for the nonlinear shallow water equations are obtained, and which local or global behavior can be determined by the corresponding Emden equation.
文摘To enhance the quality of grade 20 carbon-steel on the continuous casting production line, the mechanism of forming blowholes and non-metallic inclusions in billets and numerical simulation of flow phenomena about liquid steel in tundish were studied. The results show that the configuration and operation of tundish play an important part in quality assurance of grade 20 carbon-steel products. By optimizing the configuration of the tundish, the depth of liquid bath in tundish is enhanced, the impact of liquid steel is decreased, and the residence time of liquid steel is lengthened, which is useful for eliminating inclusions and blowholes and improving the service life of tundish. Improving the pouring and tapping operation of liquid steel can avoid the contact of liquid steel with air, and decrease re-oxidation. Strict control of the superheat degree of casting liquid steel can decrease the non-metallic inclusion content of the re-oxidation in billets and reduce the erosion of tundish. The inclusions and blowholes in the continuous casting grade 20 steel billets are reduced to a great extent and qualification rate is enhanced from 60% to 80%.
文摘Ionograms, which were obtained from February 1995 to January 1999 by a Digisonde Portable Sounder-4 (DPS-4) at Zhongshan Station in Antarctica, have been scaled. The ionograms interpretation has shown various ionosphcric phcnomena occurred in the cusp region. They are particle precipitation effects in the E region. F region magnetic noon phenomena, slant Es phenomena and lacuna. F layer irregularity zone (FLIZ) phenomena, and auroral oval identification. Typical examples of ionograms and ionogram sequences observed at Zhongshan Station are displayed in this paper.
