Particle size fraction(clay, silt, and sand) is an important characteristic that influences several soil functions. The laser-diffraction method(LDM) provides a fast and cost-effective measurement of particle size dis...Particle size fraction(clay, silt, and sand) is an important characteristic that influences several soil functions. The laser-diffraction method(LDM) provides a fast and cost-effective measurement of particle size distribution, but the results usually differ from those obtained by the traditional sieve-pipette method(SPM). This difference can persist even when calibration is applied between the two methods. This partly relates to the different size ranges of particles measured by the two methods as a result of different operational principles, i.e., particle sedimentation according to Stokes’ Law vs. Mie theory for laser beam scattering. The objective of this study was to identify particle size ranges of LDM equivalent to those measured by SPM and evaluate whether new calibration models based on size range correction can be used to improve LDM-estimated particle size fractions, using 51 soil samples with various texture collected from five soil orders in New Zealand. Particle size distribution was determined using both LDM and SPM. Compared with SPM, original data from LDM underestimated the clay fraction(< 2 μm), overestimated the silt fraction(2–53 μm), but provided a good estimation of the sand fraction(53–2 000 μm).Results from three statistical indices, including Pearson’s correlation coefficient, slope, and Lin’s concordance correlation coefficient, showed that the size ranges of < 2 and 2–53 μm defined by SPM corresponded with the < 5 and 5–53 μm size ranges by LDM, respectively. Compared with the traditional calibration(based on the same particle size ranges), new calibration models(based on the corrected size ranges of these two methods) improved the estimation of clay and silt contents by LDM. Compared with soil-specific models(i.e., different models were developed for different soils), a universal model may be more parsimonious for estimating particle size fractions if the samples to be assessed represent multiple soil orders.展开更多
Objective: to explore the application of dry chemistry method and urine sediment method in routine urine test. Methods: from May 2020 to October 2021, a total of 150 patients underwent routine urine test in our hospit...Objective: to explore the application of dry chemistry method and urine sediment method in routine urine test. Methods: from May 2020 to October 2021, a total of 150 patients underwent routine urine test in our hospital. All patients underwent routine urine test by dry chemical method, urinary sediment method and combined method, and the test results were analyzed and compared. Results: there was no difference between dry chemical method and urine sediment method in the indexes of red blood cell, white blood cell and transparent cast. In terms of the positive detection rate of quantitative red blood cells, there was no difference between dry chemical method and urine sediment method, 31.33% for the combined test method, which was significantly higher than the detection rate of the two methods, and the difference was statistically significant (p < 0.01). In terms of quantitative detection rate of leukocytes, urinary sediment method was higher than dry chemical method [30.67%vs.2.67%], p < 0.05;The combined test method was 42.67%, which was higher than the previous two methods and the difference was statistically significant (P < 0.01). As for the accuracy rate of urinary tract infection, the combined test method is 96.67%, the chemical method is 78%, and the urinary sediment method is 83.33%, the former is higher than the latter, the difference is statistically significant (p < 0.01);In terms of sensitivity, the combined test method was 96.88%, which was higher than that of dry chemical method (82.03%) and urinary sediment method (87.5%) (P < 0.01). In terms of specificity, the combined test method was 95.45%, the dry chemical method was 54.55%, and the urine sediment method was 59.09%, the former was higher than the latter, the difference was statistically significant (p < 0.01);In terms of bacterial culture results, the comparison of bacterial culture results of dry chemical method and urine sediment method shows that there is no difference in positive detection between the two detection methods, P > 0.05. The positive rate of the combined test method was significantly higher than that of the other two methods (p < 0.05). Conclusion: in routine urine test, dry chemistry method or urine sediment method alone cannot meet the test requirements, and misdiagnosis is easy to occur in the test results. Therefore, two methods of combined test are needed, which can further improve the accuracy and sensitivity of the test results. Therefore, the dry chemical method combined with urinary sediment method is effective and worthy of wide application in clinical testing.展开更多
Numerical techniques have increasingly been used to model fluid–particle two-phase flows. Coupling the immersed boundary method （IBM） and discrete element method （DEM） is one promising approach for modeling parti...Numerical techniques have increasingly been used to model fluid–particle two-phase flows. Coupling the immersed boundary method （IBM） and discrete element method （DEM） is one promising approach for modeling particulate flows. In this study, IBM was coupled with DEM to improve the reliability and accuracy of IBM for determining the positions of particles during the sedimentation process within viscous fluids. The required ratio of the particle diameter to the grid size （D/dx） was determined by comparing the simulation results with the analytical solution and experimental data. A dynamic mesh refinement model was utilised in the IBM model to refine the computational fluid dynamics grid near the particles. In addition, an optimum coupling interval between the IBM and DEM models was determined based on the experimental results of a single particle sedimentation within silicon oil at a Reynolds number of 1.5. The experimental results and the analytical solution were then utilised to validate the IBM–DEM model at Reynolds numbers of 4.1, 11.6, and 31.9. Finally, the validated model was utilised to investigate the sedimentation process for more than one particle by modeling the drafting-kissing-tumbling process and the Boycott phenomenon. Benchmark tests showed that the IBM–DEM technique preserves the advantages of DEM for tracking a group of particles, while the IBM provides a reliable and accurate approach for modeling the particle–fluid interaction.展开更多
The air microbial species and quantities in a wood mill in Harbin, China weremeasured using sedimentation plate method. Results showed that the microbial quantity in the air atthe workshop without depurator (54939 cfu...The air microbial species and quantities in a wood mill in Harbin, China weremeasured using sedimentation plate method. Results showed that the microbial quantity in the air atthe workshop without depurator (54939 cfu·m^(-3)) was 2.1 times that of the workshop withdepu-rator (25768 cfu·m^(-3)). The depurator could purify air microorganisms at the workshop, witha purifying rate of 53.1%, but it did not reach the standards of clean air. Comparatively thedepurator is effective in reducing the quantity of air actinomyces, and some kinds of airactinomyces, such as Scabies, Cinereas and Hygroscopicas, can be clean out, but it is not veryeffective to bacteria and fungi. It is suggested that more effective and feasible methods should bedeveloped for purifying air microorganisms at the workshop in the future.展开更多
Objective: to explore the application value of routine urine test in the diagnosis of urinary tract infection for patients with urinary tract infection. Methods: 70 patients with suspected urinary tract infection in o...Objective: to explore the application value of routine urine test in the diagnosis of urinary tract infection for patients with urinary tract infection. Methods: 70 patients with suspected urinary tract infection in our hospital from March 2019 to April 2020 were selected as the research objects. The urine sediment method and urine dry chemistry method were used for examination. The pathological diagnosis results were taken as the gold standard to compare the accuracy of the two methods. Results: with the pathological diagnosis results as gold, whether using urine sediment method or urine dry chemistry method to compare the white blood cell count and red blood cell in urine, it was found that when P < 0.05, there was no statistical significance. The urine sediment method and the urine dry chemical method used in the examination of the patient were tested, and the indicators in the diagnosis of urinary tract infection, such as sensitivity, specificity and accuracy were compared and analyzed, P<0.05, there was no statistical significance. Comparing the two methods, both of them can effectively detect urinary tract infection and provide reference data for subsequent treatment. Conclusion: the urine routine test of patients with urinary tract infection can significantly improve the accuracy rate of patients. The urine dry chemistry method combined with urine sediment method is less different from the gold standard results, which can significantly improve the diagnostic accuracy of patients, which is worthy of extensive promotion.展开更多
The excess water film theory and the properties of flocs are integrated to examine the effect of the polycarboxylate-type superplasticizer on the paste fluidity. The theory states that excess water can surround the fl...The excess water film theory and the properties of flocs are integrated to examine the effect of the polycarboxylate-type superplasticizer on the paste fluidity. The theory states that excess water can surround the flocs rather than the particles and that the cell consists of a floc and a superficial water film. Experiments on limestone powder pastes were conducted to verify the theory. The superplasticizer dosage （sp%） and the water-powder ratio by volume （Vw/Vv） were systematically varied. A sedimentation balance method was used to measure the size distribution of the flocs in the limestone powder pastes. The water film thickness （WFT） of flocs was then calculated and shown to determine the paste fluidity. Based on this WFT of flocs, the effect of the sp on the paste fluidity was determined and then compared with the effect of water.展开更多
In regions with broad water surfaces such as lakes, reservoirs and coastal areas, the wind stress on the flow motion generates a significant impact. The wind stress is an unsteady force which makes numerical simulatio...In regions with broad water surfaces such as lakes, reservoirs and coastal areas, the wind stress on the flow motion generates a significant impact. The wind stress is an unsteady force which makes numerical simulation difficult. This paper presents a two-dimensional （2-D） mathematical model of the impact of wind-induced motion on suspended sediment transport at Beijing＇s 13-Ling Reservoir. The model uses the Diagonal Cartesian Method （DCM） with a wetting-drying dynamic boundary to trace variations in the water level. The calculation results have been tested against in situ measurements. The measurements confirm the model＇s accuracy and agreement with the actual situation at the reservoir. The calculations also indicate that wind stress holds the key to suspended sediment transport at Beijing＇s 13-Ling Reservoir, especially when westerly winds prevail.展开更多
The purpose of this study is to establish a depth-averaged 2-D hydrodynamic and sediment transport model for the dambreak flows with vegetation effect. The generalized shallow water equations are solved using an expli...The purpose of this study is to establish a depth-averaged 2-D hydrodynamic and sediment transport model for the dambreak flows with vegetation effect. The generalized shallow water equations are solved using an explicit finite volume method with unstructured quadtree rectangular grid, and in the hydrodynamic model, a Harten-Lax-Van Leer（HLL） approximate Riemann solver is used to calculate the intercell flux for capturing the dry-to-wet moving boundary. The sediment transport and bed variation equations in a coupled fashion are calculated by including the bed variation and the variable flow density in the flow continuity and momentum equations. The drag force of vegetation is modeled as the sink terms in the momentum equations. The developed model is tested against lab experiments of the dam-break flows over a fix bed and a movable bed in vegetated and non-vegetated channels. The results are compared with experimental data, and good agreement is obtained. It is shown that the reduced velocity under vegetated conditions leads to a decrease of the peak discharge and a rise of the water level of rivers and also an enhancement of the sediment deposition.展开更多
基金completed as part of the Manaaki Whenua–Landcare Research-led MBIE Program,Soil Health and Resilience—A Pathway to Prosperity and Wellbeing(No.P/442062/01)Next Generation S-Map—Smarter Decisions(No.P/443063/01)+1 种基金the Plant&Food Research-led Strategic Science Investment Fund Program,Sustainable Agro-Ecosystemsfunded by the New Zealand Ministry of Business,Innovation and Employment。
文摘Particle size fraction(clay, silt, and sand) is an important characteristic that influences several soil functions. The laser-diffraction method(LDM) provides a fast and cost-effective measurement of particle size distribution, but the results usually differ from those obtained by the traditional sieve-pipette method(SPM). This difference can persist even when calibration is applied between the two methods. This partly relates to the different size ranges of particles measured by the two methods as a result of different operational principles, i.e., particle sedimentation according to Stokes’ Law vs. Mie theory for laser beam scattering. The objective of this study was to identify particle size ranges of LDM equivalent to those measured by SPM and evaluate whether new calibration models based on size range correction can be used to improve LDM-estimated particle size fractions, using 51 soil samples with various texture collected from five soil orders in New Zealand. Particle size distribution was determined using both LDM and SPM. Compared with SPM, original data from LDM underestimated the clay fraction(< 2 μm), overestimated the silt fraction(2–53 μm), but provided a good estimation of the sand fraction(53–2 000 μm).Results from three statistical indices, including Pearson’s correlation coefficient, slope, and Lin’s concordance correlation coefficient, showed that the size ranges of < 2 and 2–53 μm defined by SPM corresponded with the < 5 and 5–53 μm size ranges by LDM, respectively. Compared with the traditional calibration(based on the same particle size ranges), new calibration models(based on the corrected size ranges of these two methods) improved the estimation of clay and silt contents by LDM. Compared with soil-specific models(i.e., different models were developed for different soils), a universal model may be more parsimonious for estimating particle size fractions if the samples to be assessed represent multiple soil orders.
文摘Objective: to explore the application of dry chemistry method and urine sediment method in routine urine test. Methods: from May 2020 to October 2021, a total of 150 patients underwent routine urine test in our hospital. All patients underwent routine urine test by dry chemical method, urinary sediment method and combined method, and the test results were analyzed and compared. Results: there was no difference between dry chemical method and urine sediment method in the indexes of red blood cell, white blood cell and transparent cast. In terms of the positive detection rate of quantitative red blood cells, there was no difference between dry chemical method and urine sediment method, 31.33% for the combined test method, which was significantly higher than the detection rate of the two methods, and the difference was statistically significant (p < 0.01). In terms of quantitative detection rate of leukocytes, urinary sediment method was higher than dry chemical method [30.67%vs.2.67%], p < 0.05;The combined test method was 42.67%, which was higher than the previous two methods and the difference was statistically significant (P < 0.01). As for the accuracy rate of urinary tract infection, the combined test method is 96.67%, the chemical method is 78%, and the urinary sediment method is 83.33%, the former is higher than the latter, the difference is statistically significant (p < 0.01);In terms of sensitivity, the combined test method was 96.88%, which was higher than that of dry chemical method (82.03%) and urinary sediment method (87.5%) (P < 0.01). In terms of specificity, the combined test method was 95.45%, the dry chemical method was 54.55%, and the urine sediment method was 59.09%, the former was higher than the latter, the difference was statistically significant (p < 0.01);In terms of bacterial culture results, the comparison of bacterial culture results of dry chemical method and urine sediment method shows that there is no difference in positive detection between the two detection methods, P > 0.05. The positive rate of the combined test method was significantly higher than that of the other two methods (p < 0.05). Conclusion: in routine urine test, dry chemistry method or urine sediment method alone cannot meet the test requirements, and misdiagnosis is easy to occur in the test results. Therefore, two methods of combined test are needed, which can further improve the accuracy and sensitivity of the test results. Therefore, the dry chemical method combined with urinary sediment method is effective and worthy of wide application in clinical testing.
文摘Numerical techniques have increasingly been used to model fluid–particle two-phase flows. Coupling the immersed boundary method （IBM） and discrete element method （DEM） is one promising approach for modeling particulate flows. In this study, IBM was coupled with DEM to improve the reliability and accuracy of IBM for determining the positions of particles during the sedimentation process within viscous fluids. The required ratio of the particle diameter to the grid size （D/dx） was determined by comparing the simulation results with the analytical solution and experimental data. A dynamic mesh refinement model was utilised in the IBM model to refine the computational fluid dynamics grid near the particles. In addition, an optimum coupling interval between the IBM and DEM models was determined based on the experimental results of a single particle sedimentation within silicon oil at a Reynolds number of 1.5. The experimental results and the analytical solution were then utilised to validate the IBM–DEM model at Reynolds numbers of 4.1, 11.6, and 31.9. Finally, the validated model was utilised to investigate the sedimentation process for more than one particle by modeling the drafting-kissing-tumbling process and the Boycott phenomenon. Benchmark tests showed that the IBM–DEM technique preserves the advantages of DEM for tracking a group of particles, while the IBM provides a reliable and accurate approach for modeling the particle–fluid interaction.
文摘The air microbial species and quantities in a wood mill in Harbin, China weremeasured using sedimentation plate method. Results showed that the microbial quantity in the air atthe workshop without depurator (54939 cfu·m^(-3)) was 2.1 times that of the workshop withdepu-rator (25768 cfu·m^(-3)). The depurator could purify air microorganisms at the workshop, witha purifying rate of 53.1%, but it did not reach the standards of clean air. Comparatively thedepurator is effective in reducing the quantity of air actinomyces, and some kinds of airactinomyces, such as Scabies, Cinereas and Hygroscopicas, can be clean out, but it is not veryeffective to bacteria and fungi. It is suggested that more effective and feasible methods should bedeveloped for purifying air microorganisms at the workshop in the future.
文摘Objective: to explore the application value of routine urine test in the diagnosis of urinary tract infection for patients with urinary tract infection. Methods: 70 patients with suspected urinary tract infection in our hospital from March 2019 to April 2020 were selected as the research objects. The urine sediment method and urine dry chemistry method were used for examination. The pathological diagnosis results were taken as the gold standard to compare the accuracy of the two methods. Results: with the pathological diagnosis results as gold, whether using urine sediment method or urine dry chemistry method to compare the white blood cell count and red blood cell in urine, it was found that when P < 0.05, there was no statistical significance. The urine sediment method and the urine dry chemical method used in the examination of the patient were tested, and the indicators in the diagnosis of urinary tract infection, such as sensitivity, specificity and accuracy were compared and analyzed, P<0.05, there was no statistical significance. Comparing the two methods, both of them can effectively detect urinary tract infection and provide reference data for subsequent treatment. Conclusion: the urine routine test of patients with urinary tract infection can significantly improve the accuracy rate of patients. The urine dry chemistry method combined with urine sediment method is less different from the gold standard results, which can significantly improve the diagnostic accuracy of patients, which is worthy of extensive promotion.
基金supported by the National High-Tech Research and Development Program of China("863" Project)(Grant No.2012AA06A112)the National Natural Science Foundation of China(Grant No.51239006)the National Key Laboratory in China(Grant No.2012-Ky-02)
文摘The excess water film theory and the properties of flocs are integrated to examine the effect of the polycarboxylate-type superplasticizer on the paste fluidity. The theory states that excess water can surround the flocs rather than the particles and that the cell consists of a floc and a superficial water film. Experiments on limestone powder pastes were conducted to verify the theory. The superplasticizer dosage （sp%） and the water-powder ratio by volume （Vw/Vv） were systematically varied. A sedimentation balance method was used to measure the size distribution of the flocs in the limestone powder pastes. The water film thickness （WFT） of flocs was then calculated and shown to determine the paste fluidity. Based on this WFT of flocs, the effect of the sp on the paste fluidity was determined and then compared with the effect of water.
基金the National Natural Science Foundation of China (Grant Nos. 50325929 and 50221903).
文摘In regions with broad water surfaces such as lakes, reservoirs and coastal areas, the wind stress on the flow motion generates a significant impact. The wind stress is an unsteady force which makes numerical simulation difficult. This paper presents a two-dimensional （2-D） mathematical model of the impact of wind-induced motion on suspended sediment transport at Beijing＇s 13-Ling Reservoir. The model uses the Diagonal Cartesian Method （DCM） with a wetting-drying dynamic boundary to trace variations in the water level. The calculation results have been tested against in situ measurements. The measurements confirm the model＇s accuracy and agreement with the actual situation at the reservoir. The calculations also indicate that wind stress holds the key to suspended sediment transport at Beijing＇s 13-Ling Reservoir, especially when westerly winds prevail.
基金supported by the Public Science and Technology Research Funds Projects of Ocean(Grant No.201205023)the Program for Liaoning Province Excellent Talents in University(Grant No.LJQ2013077)+1 种基金the Science and Technology Founda-tion of Dalian City(Grant No.2013J21DW009)the Natu-ral Science Foundation of Liaoning Province(Grant No.2014020148)
文摘The purpose of this study is to establish a depth-averaged 2-D hydrodynamic and sediment transport model for the dambreak flows with vegetation effect. The generalized shallow water equations are solved using an explicit finite volume method with unstructured quadtree rectangular grid, and in the hydrodynamic model, a Harten-Lax-Van Leer（HLL） approximate Riemann solver is used to calculate the intercell flux for capturing the dry-to-wet moving boundary. The sediment transport and bed variation equations in a coupled fashion are calculated by including the bed variation and the variable flow density in the flow continuity and momentum equations. The drag force of vegetation is modeled as the sink terms in the momentum equations. The developed model is tested against lab experiments of the dam-break flows over a fix bed and a movable bed in vegetated and non-vegetated channels. The results are compared with experimental data, and good agreement is obtained. It is shown that the reduced velocity under vegetated conditions leads to a decrease of the peak discharge and a rise of the water level of rivers and also an enhancement of the sediment deposition.
