This study proposed the newly-designed Pelagic and demersal trawls for the fishing vessels operating in Cameroonian waters in pelagic and demersal fishing grounds. The engineering performances of both trawls were inve...This study proposed the newly-designed Pelagic and demersal trawls for the fishing vessels operating in Cameroonian waters in pelagic and demersal fishing grounds. The engineering performances of both trawls were investigated using physical modelling method and analytical method based on the predicted equations. In a flume tank, a series of physical model tests based on Tauti’s law were performed to investigate the hydrodynamic and geometrical performances of both trawls and to assess the applicability of the analytical methods based on predicted equations. The results showed that in model scale, the working towing speed and door spread for the pelagic trawl were 3.5 knots and 1.85 m, respectively, and for the bottom trawl net they were 4.0 knots and 1.8 m. At that speed and door spread, the drag force, net opening height, and wing-end spread of the pelagic model trawl were 36.73 N, 0.89 m, and 0.86 m, respectively, and the swept area was 0.76 m<sup>2</sup>. Bottom trawl speed and door spread were 30.43 N, 0.38 m, and 0.45 m, respectively, and the swept area was 0.25 m<sup>2</sup>. The maximum difference between the experimental and analytical results of hydrodynamic performances was less than 56.22% and 41.45%, respectively, for pelagic and bottom trawls, the results of the geometrical performances obtained using predicted equations were close to the experimental results in the flume tank with a maximum relative error less than 12.85%. The newly developed pelagic and bottom trawls had advanced engineering performance for high catch efficiency and selectivity and could be used in commercial fishing operations in Cameroonian waters.展开更多
Buried water pipelines are vulnerable to fail or break due to excessive loading or ground displacements.Accurate evaluation of pipe performance and serviceability relies on the proper understanding of pipe-soil intera...Buried water pipelines are vulnerable to fail or break due to excessive loading or ground displacements.Accurate evaluation of pipe performance and serviceability relies on the proper understanding of pipe-soil interactions(PSI).Analytical methods are important approaches to studying PSI.However,a systematic and thorough literature review to analyze the existing research trends,technological achievements and future research opportunities is not available.This work investigates analytical methods that analyze the stress and deformation of pipes in terms of cross-sectional,transverse and longitudinal PSI problems.First,scientometric analysis is performed to acquire relevant research works from online databases and analyze the existing data of influential authors,productive research sources and frequent key word occurrence in the fields of interest.Second,a qualitative discussion is performed in the three categories of PSI:(1)cross-sectional,including ovalization and circumferential behaviours;(2)transverse,including seismic fault crossing,weak soil zones,ground settlement and pipe uplift;and(3)longitudinal.Third,six research opportunities are discussed,including the role of friction in cross-sectional deformation,combined effects of bending and compression,choice of soil reaction models and calibration of key parameters,effect of pipe flaws,soil spatial variability and behaviours of curved pipes.This study helps beginners familiarize themselves with PSI analytical methods and provides experienced researchers with ideas for future research directions.展开更多
Over the past decade,the swift advancement of metabolomics can be credited to significant progress in technologies such as mass spectrometry,nuclear magnetic resonance,and multivariate statistics.Currently,metabolomic...Over the past decade,the swift advancement of metabolomics can be credited to significant progress in technologies such as mass spectrometry,nuclear magnetic resonance,and multivariate statistics.Currently,metabolomics garners widespread application across diverse fields including drug research and development,early disease detection,toxicology,food and nutrition science,biology,prescription,and chinmedomics,among others.Metabolomics serves as an effective characterization technique,offering insights into physiological process alterations in vivo.These changes may result from various exogenous factors like environmental conditions,stress,medications,as well as endogenous elements including genetic and protein-based influences.The potential scientific outcomes gleaned from these insights have catalyzed the formulation of innovative methods,poised to further broaden the scope of this domain.Today,metabolomics has evolved into a valuable and widely accepted instrument in the life sciences.However,comprehensive reviews focusing on the sample preparation and analytical methodologies employed in metabolomics within the life sciences are surprisingly scant.This review aims to fill that gap,providing an overview of current trends and recent advancements in metabolomics.Particular emphasis is placed on sample preparation,sophisticated analytical techniques,and their applications in life science research.展开更多
A versatile analytical method(VAM) for calculating the harmonic components of the magnetomotive force(MMF) generated by diverse armature windings in AC machines has been proposed, and the versatility of this method ha...A versatile analytical method(VAM) for calculating the harmonic components of the magnetomotive force(MMF) generated by diverse armature windings in AC machines has been proposed, and the versatility of this method has been established in early literature. However, its practical applications and significance in advancing the analysis of AC machines need further elaboration. This paper aims to complement VAM by augmenting its theory, offering additional insights into its conclusions, as well as demonstrating its utility in assessing armature windings and its application of calculating torque for permanent magnet synchronous machines(PMSM). This work contributes to advancing the analysis of AC machines and underscores the potential for improved design and performance optimization.展开更多
The laboratories in the bauxite processing industry are always under a heavy workload of sample collection, analysis, and compilation of the results. After size reduction from grinding mills, the samples of bauxite ar...The laboratories in the bauxite processing industry are always under a heavy workload of sample collection, analysis, and compilation of the results. After size reduction from grinding mills, the samples of bauxite are collected after intervals of 3 to 4 hours. Large bauxite processing industries producing 1 million tons of pure aluminium can have three grinding mills. Thus, the total number of samples to be tested in one day reaches a figure of 18 to 24. The sample of bauxite ore coming from the grinding mill is tested for its particle size and composition. For testing the composition, the bauxite ore sample is first prepared by fusing it with X-ray flux. Then the sample is sent for X-ray fluorescence analysis. Afterwards, the crucibles are washed in ultrasonic baths to be used for the next testing. The whole procedure takes about 2 - 3 hours. With a large number of samples reaching the laboratory, the chances of error in composition analysis increase. In this study, we have used a composite sampling methodology to reduce the number of samples reaching the laboratory without compromising their validity. The results of the average composition of fifteen samples were measured against composite samples. The mean of difference was calculated. The standard deviation and paired t-test values were evaluated against predetermined critical values obtained using a two-tailed test. It was found from the results that paired test-t values were much lower than the critical values thus validating the composition attained through composite sampling. The composite sampling approach not only reduced the number of samples but also the chemicals used in the laboratory. The objective of improved analytical protocol to reduce the number of samples reaching the laboratory was successfully achieved without compromising the quality of analytical results.展开更多
In recent times, the overall interest over Supercritical Fluid Chromatography (SFC) is truly growing within various domains but especially for pharmaceutical analysis. However, in the best of our knowledge modern SFC ...In recent times, the overall interest over Supercritical Fluid Chromatography (SFC) is truly growing within various domains but especially for pharmaceutical analysis. However, in the best of our knowledge modern SFC is not yet applied for drug quality control in the daily routine framework. Among the numerous reported SFC methods, none of them could be found to fully satisfy to all steps of the analytical method lifecycle. Thereby, the present contribution aims to provide an overview of the current and past achievements related to SFC techniques, with a targeted attention to this lifecycle and its successive steps. The included discussions were therefore structured accordingly and emphasizing the analytical method lifecycle in accord with the International Conference on Harmonisation (ICH). Recent and important scientific outputs in the field of analytical SFC, as well as instrumental evolution, qualification strategies, method development methodologies and discussions on the topic of method validation are reviewed.展开更多
With the development of modern industry and ever more complex structural loads,the possibility of fatigue failure is increasing.Fatigue analysis can be used to evaluate the service life of components and reduce the pr...With the development of modern industry and ever more complex structural loads,the possibility of fatigue failure is increasing.Fatigue analysis can be used to evaluate the service life of components and reduce the probability of accidents.Therefore,the development and application of fatigue-analysis technology have important research significance.This paper collects information from a wide field of literature and summarizes the current status of fatigue-analysis research.It covers related theoretical knowledge,fatigue-life prediction methods,and fatigue design methods and their application scenarios,and it summarizes the challenges and research hotspots in the field.On the basis of this examination,future development directions of fatigue-life prediction methods are proposed.The conclusions will have a certain guiding role in the development of fatigue-analysis methods.展开更多
An anisotropic diffusion filter can be used to model a flow-dependent background error covariance matrix,which can be achieved by solving the advection-diffusion equation.Because of the directionality of the advection...An anisotropic diffusion filter can be used to model a flow-dependent background error covariance matrix,which can be achieved by solving the advection-diffusion equation.Because of the directionality of the advection term,the discrete method needs to be chosen very carefully.The finite analytic method is an alternative scheme to solve the advection-diffusion equation.As a combination of analytical and numerical methods,it not only has high calculation accuracy but also holds the characteristic of the auto upwind.To demonstrate its ability,the one-dimensional steady and unsteady advection-diffusion equation numerical examples are respectively solved by the finite analytic method.The more widely used upwind difference method is used as a control approach.The result indicates that the finite analytic method has higher accuracy than the upwind difference method.For the two-dimensional case,the finite analytic method still has a better performance.In the three-dimensional variational assimilation experiment,the finite analytic method can effectively improve analysis field accuracy,and its effect is significantly better than the upwind difference and the central difference method.Moreover,it is still a more effective solution method in the strong flow region where the advective-diffusion filter performs most prominently.展开更多
Leighton Chajnantor Telescope(LCT), i.e., the former Caltech Submillimeter Observatory telescope, will be refurbished at the new site in Chajnantor Plateau, Chile in 2023. The environment of LCT will change significan...Leighton Chajnantor Telescope(LCT), i.e., the former Caltech Submillimeter Observatory telescope, will be refurbished at the new site in Chajnantor Plateau, Chile in 2023. The environment of LCT will change significantly after its relocation, and the telescope will be exposed to large wind disturbances directly because its enclosure will be completely open during observation. The wind disturbance is expected to be a challenge for LCT's pointing control since the existing control method cannot reject this disturbance very well. Therefore, it is very necessary to develop a new pointing control method with good capability of disturbance rejection. In this research, a disturbance observer—based composite position controller(DOB-CPC) is designed, in which an H∞feedback controller is employed to compress the disturbance, and a feedforward linear quadratic regulator is employed to compensate the disturbance precisely based on the estimated disturbance signal. Moreover, a controller switching policy is adopted, which applies the proportional controller to the transient process to achieve a quick response and applies the DOB-CPC to the steady state to achieve a small position error. Numerical experiments are conducted to verify the good performance of the proposed pointing controller(i.e., DOB-CPC) for rejecting the disturbance acting on LCT.展开更多
The simulation of radio frequency interference(RFI) cancellation by applying a spatial filtering technique for phased array feed(PAF) is presented. In order to better reflect the characteristics of PAF, a new signal m...The simulation of radio frequency interference(RFI) cancellation by applying a spatial filtering technique for phased array feed(PAF) is presented. In order to better reflect the characteristics of PAF, a new signal model is to add the coupling coefficient among elements of PAF to the conventional array signal model. Then the subspace projection(SP) algorithm is used to cancel RFI from the correlation matrix of the signal, and finally, the 2D power image is drawn. The power variation of signal-of-interest direction and RFI direction before and after using the SP algorithm is analyzed. The new signal model and simulation strategy can be used to test and verify the beamformer.展开更多
Circumferential yielding lining is able to tolerate controlled displacements without failure,which has been proven to be an effective solution to large deformation problem in squeezing tunnels.However,up to now,there ...Circumferential yielding lining is able to tolerate controlled displacements without failure,which has been proven to be an effective solution to large deformation problem in squeezing tunnels.However,up to now,there has not been a well-established design method for it.This paper aims to present a detailed analytical computation of support characteristic curve(SCC)for circumferential yielding lining,which is a significant aspect of the implementation of convergence-confinement method(CCM)in tunnel support design.Circumferential yielding lining consists of segmental shotcrete linings and highly deformable elements,and its superior performance mainly depends on the mechanical characteristic of highly deformable element.The deformation behavior of highly deformable element is firstly investigated.Its whole deforming process can be divided into three stages including elastic,yielding and compaction stages.Especially in the compaction stage of highly deformable element,a nonlinear stress-strain relationship can be observed.For mathematical convenience,the stress-strain curve in this period is processed as several linear sub-curves.Then,the reasons for closure of circumferential yielding lining in different stages are explained,and the corresponding accurate equations required for constructing the SCC are provided.Furthermore,this paper carries out two case studies illustrating the application of all equations needed to construct the SCC for circumferential yielding lining,where the reliability and feasibility of theoretical derivation are also well verified.Finally,this paper discusses the sensitivity of sub-division in element compaction stage and the influence of element length on SCC.The outcome of this paper could be used in the design of proper circumferential yielding lining.展开更多
The size-dependent nonlinear buckling and postbuckling characteristics of circular cylindrical nanoshells subjected to the axial compressive load are investigated with an analytical approach. The surface energy effect...The size-dependent nonlinear buckling and postbuckling characteristics of circular cylindrical nanoshells subjected to the axial compressive load are investigated with an analytical approach. The surface energy effects are taken into account according to the surface elasticity theory of Gurtin and Murdoch. The developed geometrically nonlinear shell model is based on the classical Donnell shell theory and the von K′arm′an's hypothesis. With the numerical results, the effect of the surface stress on the nonlinear buckling and postbuckling behaviors of nanoshells made of Si and Al is studied. Moreover, the influence of the surface residual tension and the radius-to-thickness ratio is illustrated.The results indicate that the surface stress has an important effect on prebuckling and postbuckling characteristics of nanoshells with small sizes.展开更多
Edible oil is an important part of the human daily diet,which is popular in the food industry.People are paying increasing attention to the safety of edible oil as flawed oils have caused enormous international losses...Edible oil is an important part of the human daily diet,which is popular in the food industry.People are paying increasing attention to the safety of edible oil as flawed oils have caused enormous international losses and posed a huge threat to consumer health issues.Therefore,it is necessary and important to analyze the quality and safety of oil product.In the present study,we particularly reviewed recent literature on analysis of emerging pollutants in edible oil including mycotoxins,pesticide residues and heavy metals.In addition,a series of emerging analytical technologies(HPLC,LC-MS/MS and GC-MS)for these contaminants were also summarized in this paper.展开更多
In order to calculate the pressure distribution of radial grooved thrust bearing,analytical and numerical methods were applied respectively.Grooved region and land region were linked by using the mass conservations pr...In order to calculate the pressure distribution of radial grooved thrust bearing,analytical and numerical methods were applied respectively.Grooved region and land region were linked by using the mass conservations principle at the groove/land boundary in each method.The block-weight approach was implemented to deal with the non-coincidence of mesh and radial groove pattern in numerical method.It was observed that the numerical solutions had higher precision as mesh number exceed 70×70,and the relaxation iteration of differential scheme presented the fastest convergence speed when relaxation factor was close to 1.94.展开更多
Plasma density and temperature can be diagnosed by x-ray line emission measurement with crystal,and bent crystals such as von Hamos and Hall structures are proposed to improve the diffraction brightness.In this study,...Plasma density and temperature can be diagnosed by x-ray line emission measurement with crystal,and bent crystals such as von Hamos and Hall structures are proposed to improve the diffraction brightness.In this study,a straightforward solution for the focusing schemes of flat and bent crystals is provided.Simulations with XOP code are performed to validate the analytical model,and good agreements are achieved.The von Hamos or multi-cone crystal can lead to several hundred times intensity enhancements for a 200μm plasma source.This model benefits the applications of the focusing bent crystals.展开更多
Non-compliant antibiotics pose problems of therapeutic efficacy at the level of the individual, but also a serious public health problem. The objective of our study was to evaluate the quality of generic amoxicillin (...Non-compliant antibiotics pose problems of therapeutic efficacy at the level of the individual, but also a serious public health problem. The objective of our study was to evaluate the quality of generic amoxicillin (42 samples) by analytical methods in Dakar/Senegal. At 100% visual inspection of compliance;100% compliance uniformity test;at the dissolution test all > 80% (86.8% to 108.8%). The presence of amoxicillin with the following contents: Tablets (95.2% to 104.1%);Capsules (91.5% to 113.9%) and Suspensions drinkable (96.9% - 118.7%). All the samples in our study are 100% compliant according to the European and American pharmacopoeias (90% - 120%). Other studies should therefore be oriented in the direction of stability as well as the dosage of degradation products.展开更多
The main surface of a large reflector antenna is composed of thousands of panels,which are inevitably deformed under natural load,leading to a great deterioration of electrical performance of the antenna.The active su...The main surface of a large reflector antenna is composed of thousands of panels,which are inevitably deformed under natural load,leading to a great deterioration of electrical performance of the antenna.The active surface technique is an effective method to compensate antenna deformation error and has been widely used.The actuator is a complex component,it has not been established in the antenna structure analysis model,which limits the theoretical analysis ability of the active surface technology.To solve this problem,an integrated structure analysis method of active surface antenna by using the simplified actuator is proposed.First,according to the supporting characteristics and adjusting function of the actuator,the complex actuator is simplified a simple structure of support beams,support truss and adjustment beam.Second,the finite element model of the active surface antenna including the simplified actuator is established.Then,the relationship between the adjustment value(load)of adjustment beam and the deformation of the antenna structure is deduced,and the integrated analysis method for realizing the active adjustment of panels is established.Finally,the model and adjustment analysis method of the active surface antenna in this paper is applied to an 8 m antenna,and satisfactory structural analysis results are obtained,which shows the effectiveness and universality of the method,and provides a reference for the modeling and adjustment analysis of the active surface antenna.展开更多
The N-1 criterion is a critical factor for ensuring the reliable and resilient operation of electric power distribution networks.However,the increasing complexity of distribution networks and the associated growth in ...The N-1 criterion is a critical factor for ensuring the reliable and resilient operation of electric power distribution networks.However,the increasing complexity of distribution networks and the associated growth in data size have created a significant challenge for distribution network planners.To address this issue,we propose a fast N-1 verification procedure for urban distribution networks that combines CIM file data analysis with MILP-based mathematical modeling.Our proposed method leverages the principles of CIM file analysis for distribution network N-1 analysis.We develop a mathematical model of distribution networks based on CIM data and transfer it into MILP.We also take into account the characteristics of medium voltage distribution networks after a line failure and select the feeder section at the exit of each substation with a high load rate to improve the efficiency of N-1 analysis.We validate our approach through a series of case studies and demonstrate its scalability and superiority over traditional N-1 analysis and heuristic optimization algorithms.By enabling online N-1 analysis,our approach significantly improves the work efficiency of distribution network planners.In summary,our proposed method provides a valuable tool for distribution network planners to enhance the accuracy and efficiency of their N-1 analyses.By leveraging the advantages of CIM file data analysis and MILP-based mathematical modeling,our approach contributes to the development of more resilient and reliable electric power distribution networks.展开更多
This paper reports site survey results for the Infrared System for the Accurate Measurement of Solar Magnetic Field, especially in Saishiteng Mountain, Qinghai, China. Since 2017, we have installed a weather station,s...This paper reports site survey results for the Infrared System for the Accurate Measurement of Solar Magnetic Field, especially in Saishiteng Mountain, Qinghai, China. Since 2017, we have installed a weather station,spectrometers for precipitable water vapor, and Solar Differential Image Motion Monitor, and have carried out observations on weather elements, precipitable water vapor, and daytime seeing conditions for more than one year in almost all candidates. At Mt. Saishiteng, the median value of daytime precipitable water vapor is 5.25 mm and its median value in winter season is 2.1 mm. The median value of the Fried parameter of daytime seeing observation at Saishiteng Mountain is 3.42 cm. Its solar direct radiation data show that solar average observable time is 446 minutes per day and premium time is 401 minutes per day in 2019 August.展开更多
We present the detailed fundamental stellar parameters of the close visual binary system HD 39438 for the first time. We used Al-Wardat's method for analyzing binary and multiple stellar systems. The method implem...We present the detailed fundamental stellar parameters of the close visual binary system HD 39438 for the first time. We used Al-Wardat's method for analyzing binary and multiple stellar systems. The method implements Kurucz's plane parallel model atmospheres to construct synthetic spectral energy distributions(SEDs) for both components of the system. It then combines the results of the spectroscopic analysis with the photometric analysis and compares them with the observed ones to construct the best synthetic SED for the combined system. The analysis gives the precise fundamental parameters of the individual components of the system. Based on the positions of the components of HD 39438 on the H-R diagram, and evolutionary and isochrone tracks, we found that the system belongs to the main sequence stars with masses of 1.24 and 0.98 solar masses for the components A and B, respectively, and age of 1.995 Gyr for both components. The main result of HD 39438 is new dynamical parallax, which is estimated to be 16.689 ± 0.03 mas.展开更多
文摘This study proposed the newly-designed Pelagic and demersal trawls for the fishing vessels operating in Cameroonian waters in pelagic and demersal fishing grounds. The engineering performances of both trawls were investigated using physical modelling method and analytical method based on the predicted equations. In a flume tank, a series of physical model tests based on Tauti’s law were performed to investigate the hydrodynamic and geometrical performances of both trawls and to assess the applicability of the analytical methods based on predicted equations. The results showed that in model scale, the working towing speed and door spread for the pelagic trawl were 3.5 knots and 1.85 m, respectively, and for the bottom trawl net they were 4.0 knots and 1.8 m. At that speed and door spread, the drag force, net opening height, and wing-end spread of the pelagic model trawl were 36.73 N, 0.89 m, and 0.86 m, respectively, and the swept area was 0.76 m<sup>2</sup>. Bottom trawl speed and door spread were 30.43 N, 0.38 m, and 0.45 m, respectively, and the swept area was 0.25 m<sup>2</sup>. The maximum difference between the experimental and analytical results of hydrodynamic performances was less than 56.22% and 41.45%, respectively, for pelagic and bottom trawls, the results of the geometrical performances obtained using predicted equations were close to the experimental results in the flume tank with a maximum relative error less than 12.85%. The newly developed pelagic and bottom trawls had advanced engineering performance for high catch efficiency and selectivity and could be used in commercial fishing operations in Cameroonian waters.
基金The authors gratefully acknowledge the Innovation and Technology Support Programme(ITSP)[Grant No.ITS/033/20FP]the Water Supplies Department of Hong Kong,China.Suggestions given by Dr.Andy Y.F.Leung are also appreciated.
文摘Buried water pipelines are vulnerable to fail or break due to excessive loading or ground displacements.Accurate evaluation of pipe performance and serviceability relies on the proper understanding of pipe-soil interactions(PSI).Analytical methods are important approaches to studying PSI.However,a systematic and thorough literature review to analyze the existing research trends,technological achievements and future research opportunities is not available.This work investigates analytical methods that analyze the stress and deformation of pipes in terms of cross-sectional,transverse and longitudinal PSI problems.First,scientometric analysis is performed to acquire relevant research works from online databases and analyze the existing data of influential authors,productive research sources and frequent key word occurrence in the fields of interest.Second,a qualitative discussion is performed in the three categories of PSI:(1)cross-sectional,including ovalization and circumferential behaviours;(2)transverse,including seismic fault crossing,weak soil zones,ground settlement and pipe uplift;and(3)longitudinal.Third,six research opportunities are discussed,including the role of friction in cross-sectional deformation,combined effects of bending and compression,choice of soil reaction models and calibration of key parameters,effect of pipe flaws,soil spatial variability and behaviours of curved pipes.This study helps beginners familiarize themselves with PSI analytical methods and provides experienced researchers with ideas for future research directions.
基金supported by the Science Foundation of Heilongjiang Administration of Traditional Chinese Medicine(No.2018-21).
文摘Over the past decade,the swift advancement of metabolomics can be credited to significant progress in technologies such as mass spectrometry,nuclear magnetic resonance,and multivariate statistics.Currently,metabolomics garners widespread application across diverse fields including drug research and development,early disease detection,toxicology,food and nutrition science,biology,prescription,and chinmedomics,among others.Metabolomics serves as an effective characterization technique,offering insights into physiological process alterations in vivo.These changes may result from various exogenous factors like environmental conditions,stress,medications,as well as endogenous elements including genetic and protein-based influences.The potential scientific outcomes gleaned from these insights have catalyzed the formulation of innovative methods,poised to further broaden the scope of this domain.Today,metabolomics has evolved into a valuable and widely accepted instrument in the life sciences.However,comprehensive reviews focusing on the sample preparation and analytical methodologies employed in metabolomics within the life sciences are surprisingly scant.This review aims to fill that gap,providing an overview of current trends and recent advancements in metabolomics.Particular emphasis is placed on sample preparation,sophisticated analytical techniques,and their applications in life science research.
基金supported by the Natural Science Foundation of China under Grant U22A20214 and Grant 51837010。
文摘A versatile analytical method(VAM) for calculating the harmonic components of the magnetomotive force(MMF) generated by diverse armature windings in AC machines has been proposed, and the versatility of this method has been established in early literature. However, its practical applications and significance in advancing the analysis of AC machines need further elaboration. This paper aims to complement VAM by augmenting its theory, offering additional insights into its conclusions, as well as demonstrating its utility in assessing armature windings and its application of calculating torque for permanent magnet synchronous machines(PMSM). This work contributes to advancing the analysis of AC machines and underscores the potential for improved design and performance optimization.
文摘The laboratories in the bauxite processing industry are always under a heavy workload of sample collection, analysis, and compilation of the results. After size reduction from grinding mills, the samples of bauxite are collected after intervals of 3 to 4 hours. Large bauxite processing industries producing 1 million tons of pure aluminium can have three grinding mills. Thus, the total number of samples to be tested in one day reaches a figure of 18 to 24. The sample of bauxite ore coming from the grinding mill is tested for its particle size and composition. For testing the composition, the bauxite ore sample is first prepared by fusing it with X-ray flux. Then the sample is sent for X-ray fluorescence analysis. Afterwards, the crucibles are washed in ultrasonic baths to be used for the next testing. The whole procedure takes about 2 - 3 hours. With a large number of samples reaching the laboratory, the chances of error in composition analysis increase. In this study, we have used a composite sampling methodology to reduce the number of samples reaching the laboratory without compromising their validity. The results of the average composition of fifteen samples were measured against composite samples. The mean of difference was calculated. The standard deviation and paired t-test values were evaluated against predetermined critical values obtained using a two-tailed test. It was found from the results that paired test-t values were much lower than the critical values thus validating the composition attained through composite sampling. The composite sampling approach not only reduced the number of samples but also the chemicals used in the laboratory. The objective of improved analytical protocol to reduce the number of samples reaching the laboratory was successfully achieved without compromising the quality of analytical results.
文摘In recent times, the overall interest over Supercritical Fluid Chromatography (SFC) is truly growing within various domains but especially for pharmaceutical analysis. However, in the best of our knowledge modern SFC is not yet applied for drug quality control in the daily routine framework. Among the numerous reported SFC methods, none of them could be found to fully satisfy to all steps of the analytical method lifecycle. Thereby, the present contribution aims to provide an overview of the current and past achievements related to SFC techniques, with a targeted attention to this lifecycle and its successive steps. The included discussions were therefore structured accordingly and emphasizing the analytical method lifecycle in accord with the International Conference on Harmonisation (ICH). Recent and important scientific outputs in the field of analytical SFC, as well as instrumental evolution, qualification strategies, method development methodologies and discussions on the topic of method validation are reviewed.
基金financially supported by China Postdoctoral Science Foundationthe National Natural Science Foundation of China(Grant No.51705132)+1 种基金the Natural Science Project of Henan Provincial Department of Science and Technology(Grant No.222102220088)the Natural Science Project of Henan Provincial Department of Education(Grant No.21A460006)。
文摘With the development of modern industry and ever more complex structural loads,the possibility of fatigue failure is increasing.Fatigue analysis can be used to evaluate the service life of components and reduce the probability of accidents.Therefore,the development and application of fatigue-analysis technology have important research significance.This paper collects information from a wide field of literature and summarizes the current status of fatigue-analysis research.It covers related theoretical knowledge,fatigue-life prediction methods,and fatigue design methods and their application scenarios,and it summarizes the challenges and research hotspots in the field.On the basis of this examination,future development directions of fatigue-life prediction methods are proposed.The conclusions will have a certain guiding role in the development of fatigue-analysis methods.
基金The National Key Research and Development Program of China under contract Nos 2022YFC3104804,2021YFC3101501,and 2017YFC1404103the National Programme on Global Change and Air-Sea Interaction of China under contract No.GASI-IPOVAI-04the National Natural Science Foundation of China under contract Nos 41876014,41606039,and 11801402.
文摘An anisotropic diffusion filter can be used to model a flow-dependent background error covariance matrix,which can be achieved by solving the advection-diffusion equation.Because of the directionality of the advection term,the discrete method needs to be chosen very carefully.The finite analytic method is an alternative scheme to solve the advection-diffusion equation.As a combination of analytical and numerical methods,it not only has high calculation accuracy but also holds the characteristic of the auto upwind.To demonstrate its ability,the one-dimensional steady and unsteady advection-diffusion equation numerical examples are respectively solved by the finite analytic method.The more widely used upwind difference method is used as a control approach.The result indicates that the finite analytic method has higher accuracy than the upwind difference method.For the two-dimensional case,the finite analytic method still has a better performance.In the three-dimensional variational assimilation experiment,the finite analytic method can effectively improve analysis field accuracy,and its effect is significantly better than the upwind difference and the central difference method.Moreover,it is still a more effective solution method in the strong flow region where the advective-diffusion filter performs most prominently.
文摘Leighton Chajnantor Telescope(LCT), i.e., the former Caltech Submillimeter Observatory telescope, will be refurbished at the new site in Chajnantor Plateau, Chile in 2023. The environment of LCT will change significantly after its relocation, and the telescope will be exposed to large wind disturbances directly because its enclosure will be completely open during observation. The wind disturbance is expected to be a challenge for LCT's pointing control since the existing control method cannot reject this disturbance very well. Therefore, it is very necessary to develop a new pointing control method with good capability of disturbance rejection. In this research, a disturbance observer—based composite position controller(DOB-CPC) is designed, in which an H∞feedback controller is employed to compress the disturbance, and a feedforward linear quadratic regulator is employed to compensate the disturbance precisely based on the estimated disturbance signal. Moreover, a controller switching policy is adopted, which applies the proportional controller to the transient process to achieve a quick response and applies the DOB-CPC to the steady state to achieve a small position error. Numerical experiments are conducted to verify the good performance of the proposed pointing controller(i.e., DOB-CPC) for rejecting the disturbance acting on LCT.
基金funded by the National Key R&D Program of China under No. 2022YFC2205300the National Natural Science Foundation of China (12073067)the Chinese Academy of Sciences (CAS)“Light of West China” Program under No. 2022-XBQNXZ-012。
文摘The simulation of radio frequency interference(RFI) cancellation by applying a spatial filtering technique for phased array feed(PAF) is presented. In order to better reflect the characteristics of PAF, a new signal model is to add the coupling coefficient among elements of PAF to the conventional array signal model. Then the subspace projection(SP) algorithm is used to cancel RFI from the correlation matrix of the signal, and finally, the 2D power image is drawn. The power variation of signal-of-interest direction and RFI direction before and after using the SP algorithm is analyzed. The new signal model and simulation strategy can be used to test and verify the beamformer.
基金supported by National Natural Science Foundation of China(Grant Nos.11872287 and 51908431)Fund of Shaanxi Key Research and Development Program(Grant No.2019ZDLGY01-10)。
文摘Circumferential yielding lining is able to tolerate controlled displacements without failure,which has been proven to be an effective solution to large deformation problem in squeezing tunnels.However,up to now,there has not been a well-established design method for it.This paper aims to present a detailed analytical computation of support characteristic curve(SCC)for circumferential yielding lining,which is a significant aspect of the implementation of convergence-confinement method(CCM)in tunnel support design.Circumferential yielding lining consists of segmental shotcrete linings and highly deformable elements,and its superior performance mainly depends on the mechanical characteristic of highly deformable element.The deformation behavior of highly deformable element is firstly investigated.Its whole deforming process can be divided into three stages including elastic,yielding and compaction stages.Especially in the compaction stage of highly deformable element,a nonlinear stress-strain relationship can be observed.For mathematical convenience,the stress-strain curve in this period is processed as several linear sub-curves.Then,the reasons for closure of circumferential yielding lining in different stages are explained,and the corresponding accurate equations required for constructing the SCC are provided.Furthermore,this paper carries out two case studies illustrating the application of all equations needed to construct the SCC for circumferential yielding lining,where the reliability and feasibility of theoretical derivation are also well verified.Finally,this paper discusses the sensitivity of sub-division in element compaction stage and the influence of element length on SCC.The outcome of this paper could be used in the design of proper circumferential yielding lining.
文摘The size-dependent nonlinear buckling and postbuckling characteristics of circular cylindrical nanoshells subjected to the axial compressive load are investigated with an analytical approach. The surface energy effects are taken into account according to the surface elasticity theory of Gurtin and Murdoch. The developed geometrically nonlinear shell model is based on the classical Donnell shell theory and the von K′arm′an's hypothesis. With the numerical results, the effect of the surface stress on the nonlinear buckling and postbuckling behaviors of nanoshells made of Si and Al is studied. Moreover, the influence of the surface residual tension and the radius-to-thickness ratio is illustrated.The results indicate that the surface stress has an important effect on prebuckling and postbuckling characteristics of nanoshells with small sizes.
基金funded by the Applied basic research plan of Hebei province-key basic research projects(17967502D)2020-Innovation Project-An Yi.
文摘Edible oil is an important part of the human daily diet,which is popular in the food industry.People are paying increasing attention to the safety of edible oil as flawed oils have caused enormous international losses and posed a huge threat to consumer health issues.Therefore,it is necessary and important to analyze the quality and safety of oil product.In the present study,we particularly reviewed recent literature on analysis of emerging pollutants in edible oil including mycotoxins,pesticide residues and heavy metals.In addition,a series of emerging analytical technologies(HPLC,LC-MS/MS and GC-MS)for these contaminants were also summarized in this paper.
基金Supported by the Ministerial Level Foundation(2220060029)
文摘In order to calculate the pressure distribution of radial grooved thrust bearing,analytical and numerical methods were applied respectively.Grooved region and land region were linked by using the mass conservations principle at the groove/land boundary in each method.The block-weight approach was implemented to deal with the non-coincidence of mesh and radial groove pattern in numerical method.It was observed that the numerical solutions had higher precision as mesh number exceed 70×70,and the relaxation iteration of differential scheme presented the fastest convergence speed when relaxation factor was close to 1.94.
基金Project supported by the National Natural Science Fundation of China(Grant Nos.11775203 and 12075219)the China Academy of Engineering Physics(CAEP)Foundation(Grant No.CX20210019).
文摘Plasma density and temperature can be diagnosed by x-ray line emission measurement with crystal,and bent crystals such as von Hamos and Hall structures are proposed to improve the diffraction brightness.In this study,a straightforward solution for the focusing schemes of flat and bent crystals is provided.Simulations with XOP code are performed to validate the analytical model,and good agreements are achieved.The von Hamos or multi-cone crystal can lead to several hundred times intensity enhancements for a 200μm plasma source.This model benefits the applications of the focusing bent crystals.
文摘Non-compliant antibiotics pose problems of therapeutic efficacy at the level of the individual, but also a serious public health problem. The objective of our study was to evaluate the quality of generic amoxicillin (42 samples) by analytical methods in Dakar/Senegal. At 100% visual inspection of compliance;100% compliance uniformity test;at the dissolution test all > 80% (86.8% to 108.8%). The presence of amoxicillin with the following contents: Tablets (95.2% to 104.1%);Capsules (91.5% to 113.9%) and Suspensions drinkable (96.9% - 118.7%). All the samples in our study are 100% compliant according to the European and American pharmacopoeias (90% - 120%). Other studies should therefore be oriented in the direction of stability as well as the dosage of degradation products.
基金supported by the National Key Research and Development Program of China(Nos.2021YFC2203501 and 2021YFC2203601)the National Natural Science Foundation of China(No.52165053)+2 种基金the China Postdoctoral Science Foundation(2021M702751)the Tianshan Young Talent Project of Xinjiang(2020Q068)the Doctor Scientific Research Project of Xinjiang。
文摘The main surface of a large reflector antenna is composed of thousands of panels,which are inevitably deformed under natural load,leading to a great deterioration of electrical performance of the antenna.The active surface technique is an effective method to compensate antenna deformation error and has been widely used.The actuator is a complex component,it has not been established in the antenna structure analysis model,which limits the theoretical analysis ability of the active surface technology.To solve this problem,an integrated structure analysis method of active surface antenna by using the simplified actuator is proposed.First,according to the supporting characteristics and adjusting function of the actuator,the complex actuator is simplified a simple structure of support beams,support truss and adjustment beam.Second,the finite element model of the active surface antenna including the simplified actuator is established.Then,the relationship between the adjustment value(load)of adjustment beam and the deformation of the antenna structure is deduced,and the integrated analysis method for realizing the active adjustment of panels is established.Finally,the model and adjustment analysis method of the active surface antenna in this paper is applied to an 8 m antenna,and satisfactory structural analysis results are obtained,which shows the effectiveness and universality of the method,and provides a reference for the modeling and adjustment analysis of the active surface antenna.
基金supported by the National Natural Science Foundation of China(52207105)。
文摘The N-1 criterion is a critical factor for ensuring the reliable and resilient operation of electric power distribution networks.However,the increasing complexity of distribution networks and the associated growth in data size have created a significant challenge for distribution network planners.To address this issue,we propose a fast N-1 verification procedure for urban distribution networks that combines CIM file data analysis with MILP-based mathematical modeling.Our proposed method leverages the principles of CIM file analysis for distribution network N-1 analysis.We develop a mathematical model of distribution networks based on CIM data and transfer it into MILP.We also take into account the characteristics of medium voltage distribution networks after a line failure and select the feeder section at the exit of each substation with a high load rate to improve the efficiency of N-1 analysis.We validate our approach through a series of case studies and demonstrate its scalability and superiority over traditional N-1 analysis and heuristic optimization algorithms.By enabling online N-1 analysis,our approach significantly improves the work efficiency of distribution network planners.In summary,our proposed method provides a valuable tool for distribution network planners to enhance the accuracy and efficiency of their N-1 analyses.By leveraging the advantages of CIM file data analysis and MILP-based mathematical modeling,our approach contributes to the development of more resilient and reliable electric power distribution networks.
基金sponsored by the National Natural Science Foundation of China (NSFC) under grant Nos 11427901 and 12273059the National Key R&D Program of China under grant No. 2021YFA1600500。
文摘This paper reports site survey results for the Infrared System for the Accurate Measurement of Solar Magnetic Field, especially in Saishiteng Mountain, Qinghai, China. Since 2017, we have installed a weather station,spectrometers for precipitable water vapor, and Solar Differential Image Motion Monitor, and have carried out observations on weather elements, precipitable water vapor, and daytime seeing conditions for more than one year in almost all candidates. At Mt. Saishiteng, the median value of daytime precipitable water vapor is 5.25 mm and its median value in winter season is 2.1 mm. The median value of the Fried parameter of daytime seeing observation at Saishiteng Mountain is 3.42 cm. Its solar direct radiation data show that solar average observable time is 446 minutes per day and premium time is 401 minutes per day in 2019 August.
文摘We present the detailed fundamental stellar parameters of the close visual binary system HD 39438 for the first time. We used Al-Wardat's method for analyzing binary and multiple stellar systems. The method implements Kurucz's plane parallel model atmospheres to construct synthetic spectral energy distributions(SEDs) for both components of the system. It then combines the results of the spectroscopic analysis with the photometric analysis and compares them with the observed ones to construct the best synthetic SED for the combined system. The analysis gives the precise fundamental parameters of the individual components of the system. Based on the positions of the components of HD 39438 on the H-R diagram, and evolutionary and isochrone tracks, we found that the system belongs to the main sequence stars with masses of 1.24 and 0.98 solar masses for the components A and B, respectively, and age of 1.995 Gyr for both components. The main result of HD 39438 is new dynamical parallax, which is estimated to be 16.689 ± 0.03 mas.
