AGC protein kinases play important roles in plant growth and development.Several AGC kinases in Arabidopsis have been functionally characterized.However,the"AGC Other"subfamily,including IRE,IREH1,IRE3 and I...AGC protein kinases play important roles in plant growth and development.Several AGC kinases in Arabidopsis have been functionally characterized.However,the"AGC Other"subfamily,including IRE,IREH1,IRE3 and IRE4,has not been well understood.Here,we reported that ireh1 mutants displayed a root skewing phenotype,which can be enhanced by ire3 mutation.IREH1 and IRE3 were expressed in roots,consistent with their function in controlling root skewing.The fluorescence intensities of the microtubule marker KNpro:EGFP-MBD were decreased in ireh1,ire3 and ireh1 ire3 mutants compared to wild type.The microtubule arrangements in ireh1 and ireh1 ire3 mutants were also altered.IREH1 physically interacted with IRE3 in vitro and in planta.Thus,our findings demonstrate that IREH1 and IRE3 protein kinases play important roles in controlling root skewing,and maintaining microtubule network in Arabidopsis.展开更多
When the wing of Oblique Wing Aircraft(OWA)is skewed,the center of gravity,inertia and aerodynamic characteristics of the aircraft all significantly change,causing an undesirable flight dynamic response,affecting the ...When the wing of Oblique Wing Aircraft(OWA)is skewed,the center of gravity,inertia and aerodynamic characteristics of the aircraft all significantly change,causing an undesirable flight dynamic response,affecting the flying qualities,and even endangering the flight safety.In this study,the dynamic response of an OWA in the wing skewing process is simulated,showing that the threeaxis movements of the OWA are highly coupled and present nonlinear characteristics during the wing skewing.As the roll control efficiency of the aileron decreases due to the shortened control arm in an oblique configuration,the all-moving horizontal tail is used for additional roll and the control allocation is performed based on minimum control energy.Given the properties of pitchroll-yaw coupling and control input and state coupling,and the difficulty of establishing an accurate aerodynamic model in the wing skewing process due to unsteady aerodynamic force,a multi-loop sliding mode controller is formulated by the time-scale separation method.The closed-loop simulation results show that the asymmetric aerodynamics can be balanced and that the velocity and altitude of the aircraft maintain stable,which means that a smooth transition is obtained during the OWA's wing skewing.展开更多
Double Sided Linear Synchronous Reluctance Motors(DSL-SynRM)are being increasingly used in high force density applications.The force ripples are one of the major issue in machine which is due to nonlinear nature of cu...Double Sided Linear Synchronous Reluctance Motors(DSL-SynRM)are being increasingly used in high force density applications.The force ripples are one of the major issue in machine which is due to nonlinear nature of current in the machines.This paper focuses on the reduction of force ripples for increasing the force density of the motor.In order to reduce the force ripples,DSL-SynRM with a skewed translator is proposed.The proposed structure is designed and developed by using computational magnetic tools.This concept is effective for reduction of the force ripples and improves the force density of the machine.The proposed design has been reduced the percentage of force ripples by 21.62%,improved the force density by 10.32 N/mm³and efficiency by 0.89%.展开更多
Evaluating the adversarial robustness of classification algorithms in machine learning is a crucial domain.However,current methods lack measurable and interpretable metrics.To address this issue,this paper introduces ...Evaluating the adversarial robustness of classification algorithms in machine learning is a crucial domain.However,current methods lack measurable and interpretable metrics.To address this issue,this paper introduces a visual evaluation index named confidence centroid skewing quadrilateral,which is based on a classification confidence-based confusion matrix,offering a quantitative and visual comparison of the adversarial robustness among different classification algorithms,and enhances intuitiveness and interpretability of attack impacts.We first conduct a validity test and sensitive analysis of the method.Then,prove its effectiveness through the experiments of five classification algorithms including artificial neural network(ANN),logistic regression(LR),support vector machine(SVM),convolutional neural network(CNN)and transformer against three adversarial attacks such as fast gradient sign method(FGSM),DeepFool,and projected gradient descent(PGD)attack.展开更多
In this paper, a multi-physics simulation model capable of electromagnetic noise prediction is established, and the effectiveness of the established simulation model in predicting and evaluating electromagnetic noise ...In this paper, a multi-physics simulation model capable of electromagnetic noise prediction is established, and the effectiveness of the established simulation model in predicting and evaluating electromagnetic noise is verified. Based on the verified motor model, a rotor step skewing model which can affect electromagnetic noise is proposed, and the influence of the skewing angle on electromagnetic noise is investigated in detail. By studying the spectral characteristics of the low-order radial magnetic force which has a great influence on electromagnetic noise, the distribution of electromagnetic noise characteristics of the permanent magnet synchronous motor(PMSM) with or without the rotor step skewing is compared and analyzed. Therefore, it lays a technological foundation for predicting and suppressing the electromagnetic vibration noise of electric vehicle(EV) driving motor in the electromagnetic design.展开更多
In this paper, an equation for the calculation of the frictional torque of a dry-lubricated tapered roller bearing(TRB) is provided in which the effect of the roller skewing is emphasized. Calculations were performed ...In this paper, an equation for the calculation of the frictional torque of a dry-lubricated tapered roller bearing(TRB) is provided in which the effect of the roller skewing is emphasized. Calculations were performed to investigate the effect of the roller skewing on the torque of dry-lubricated TRB for two representative preload methods, that is, axial force preload and axial displacement preload. The results show that a proper roller skewing angle under axial force preload benefits the reduction of the TRB torque. However, the roller skewing angle should not exceed a certain critical value;otherwise, it will cause a steep rise in the TRB torque. Finally, the critical value of the roller skewing angle as a function of the friction coefficient and cage pocket clearance is presented. The developed torque model provides a tool for the internal design and torque optimization of dry-lubricated TRBs.展开更多
Seed dispersal is a pivotal process in seed plant life cycle,owing to its effects on seed germination,seedling survival,population recruitment,and diversity maintenance in the entire community(Howe and Smallwood,1982;...Seed dispersal is a pivotal process in seed plant life cycle,owing to its effects on seed germination,seedling survival,population recruitment,and diversity maintenance in the entire community(Howe and Smallwood,1982;Rogers et al.,2021).There are diverse dispersal modes,such as anemochory(wind-driven dispersal),hydrochory(water-mediated dispersal),autochory(self-dispersal),and zoochory,which relies on a diverse array of animals for seed dispersal(Howe and Smallwood,1982).It is widely known that these varying dispersal modes impose selective pressures on many seed and fruit traits,especially the seed size,a key trait which is associated with multiple stages of the life cycle of plants,such as dispersal,germination,and establishment,particularly during early development(Leishman et al.,2000).展开更多
We use transaction-level data from the Bitcoin exchange Mt.Gox,including over 1.4 million transactions from more than 45,000 traders,to investigate the role of technical chart patterns in the early Bitcoin market from...We use transaction-level data from the Bitcoin exchange Mt.Gox,including over 1.4 million transactions from more than 45,000 traders,to investigate the role of technical chart patterns in the early Bitcoin market from April 2011 to September 2013.Employing a pattern recognition algorithm,we identify hourly trading signals for five major chart patterns.Buy signals of these patterns are associated with an average increase in abnormal trading volume of more than 53%.Trades executed during buy signal periods yield significantly higher average returns than those made during non-signal periods.Traders who use chart patterns more frequently are more likely to generate right-skewed return distributions,engage in more active trading,and achieve higher average roundtrip returns.Our research suggests that chart pattern trading was a crucial tool for Mt.Gox clients,highlighting the importance of technical heuristics in shaping the dynamics in a less efficient and unregulated market environment.By leveraging a comprehensive transaction dataset from a major cryptocurrency exchange,we provide unique insights into the actual trading behavior of the first Bitcoin adopters.This sets our work apart from previous studies that mainly rely on backtesting technical strategies using publicly available price data.展开更多
In this study,we propose a Gram-Charlier expansion approach to investigate the impact of skewness and kurtosis on production and hedging decisions.Consistent with the existing literature,we find that skewness and kurt...In this study,we propose a Gram-Charlier expansion approach to investigate the impact of skewness and kurtosis on production and hedging decisions.Consistent with the existing literature,we find that skewness and kurtosis do not affect decisions regarding optimal production;however,they significantly influence optimal hedging decisions.We observe that positive skewness with platykurtic spot prices or negative skewness with leptokurtic spot prices often leads to over-hedging when the initial forward contract price exceeds its expected value.Conversely,under-hedging is expected when the initial forward contract price falls below its expected value.In other conditions,skewness can either promote or impede speculative future trading.Using the Gram-Charlier expansion of the spot price density function,we find that optimal future positions depend on forward prices,the hedgers’risk preference,and the spot price distribution.Simulations validate our findings on the impact of skewness and kurtosis on future hedging.Finally,we analyze of a cotton storage and forward contracting dataset to illustrate the application of our methodology and support our theoretical results.展开更多
Heart failure prediction is crucial as cardiovascular diseases become the leading cause of death worldwide,exacerbated by the COVID-19 pandemic.Age,cholesterol,and blood pressure datasets are becoming inadequate becau...Heart failure prediction is crucial as cardiovascular diseases become the leading cause of death worldwide,exacerbated by the COVID-19 pandemic.Age,cholesterol,and blood pressure datasets are becoming inadequate because they cannot capture the complexity of emerging health indicators.These high-dimensional and heterogeneous datasets make traditional machine learning methods difficult,and Skewness and other new biomarkers and psychosocial factors bias the model’s heart health prediction across diverse patient profiles.Modern medical datasets’complexity and high dimensionality challenge traditional predictionmodels like SupportVectorMachines and Decision Trees.Quantum approaches include QSVM,QkNN,QDT,and others.These Constraints drove research.The“QHF-CS:Quantum-Enhanced Heart Failure Prediction using Quantum CNN with Optimized Feature Qubit Selection with Cuckoo Search in Skewed Clinical Data”system was developed in this research.This novel system leverages a Quantum Convolutional Neural Network(QCNN)-based quantum circuit,enhanced by meta-heuristic algorithms—Cuckoo SearchOptimization(CSO),Artificial BeeColony(ABC),and Particle SwarmOptimization(PSO)—for feature qubit selection.Among these,CSO demonstrated superior performance by consistently identifying the most optimal and least skewed feature subsets,which were then encoded into quantum states for circuit construction.By integrating advanced quantum circuit feature maps like ZZFeatureMap,RealAmplitudes,and EfficientSU2,the QHF-CS model efficiently processes complex,high-dimensional data,capturing intricate patterns that classical models overlook.The QHF-CS model improves precision,recall,F1-score,and accuracy to 0.94,0.95,0.94,and 0.94.Quantum computing could revolutionize heart failure diagnostics by improving model accuracy and computational efficiency,enabling complex healthcare diagnostic breakthroughs.展开更多
The comprehension of universal thermodynamic behaviors in the supercritical region is crucial for examining the characteristics of black hole systems under high temperature and pressure.This study is devoted to the an...The comprehension of universal thermodynamic behaviors in the supercritical region is crucial for examining the characteristics of black hole systems under high temperature and pressure.This study is devoted to the analysis of characteristic lines and crossover behaviors within the supercritical region.By making use of the free energy,we introduce three key thermodynamic quantities:scaled variance,skewness,and kurtosis.Our results demonstrate that the Widom line,associated with the maximal scaled variance,can effectively differentiate between small and large black hole-like subphases,each displaying distinct thermodynamic behaviors within the supercritical region.Furthermore,by utilizing quasinormal modes,we identify the Frenkel line,offering a dynamic perspective to distinguish between small and large black hole-like subphases.These contribute to a deeper comprehension of black hole subphases in the supercritical region,thus illuminating new facets of black hole thermodynamics.展开更多
Regarding the scale effects on propeller＇s noncavitation hydrodynamics and hydroacoustics, three similar 7bladed highly-skewed propellers in the wake flow are addressed with diameters of 250, 500 and 1 000 mm, respec...Regarding the scale effects on propeller＇s noncavitation hydrodynamics and hydroacoustics, three similar 7bladed highly-skewed propellers in the wake flow are addressed with diameters of 250, 500 and 1 000 mm, respectively. The discrete line-spectrum noise and its standardized spectrum level scaling law, together with the total sound pressure level are analyzed. The non-cavitation noise predictions are completed by both the frequency domain method and the time domain method. As a fluctuated noise source, the time-dependent fluctuated pressure and normal velocity distribution on propeller blades are obtained by the unsteady Reynolds-averaged Navier-Stokes （ URANS ） simulation. Results show that the pressure coefficient distribution of three propellers on the 0.7R section is nearly superposed under the same advance ratio. The periodic thrust fluctuation of three propellers can exactly reflect the tonal components of the axial passing frequency （APF） and the blade passing frequency （BPF）, and the fluctuation enhancement from the small to the middle propeller at the BPF is greater than that from the middle to the big one. By the two noise prediction methods, the increment of the total sound pressure level from the small to the big propeller differs by 2.49 dB. Following the standardized scaling law, the spectrum curves of the middle and big propellers are nearly the same while significantly differing from the small one. The increment of both the line-spectrum level and the total sound pressure increases with the increase in diameter. It is suggested that the model scale of the propeller should be as large as possible in engineering to reduce the prediction error of the empirical scalin~ law and weaken the scale effects.展开更多
A preliminary study was conducted to outline the laser Raman spectroscopy technique for determination of salinity in the aqueous phase in fluid inclusions. The skewing parameters of the Raman profiles of the calibrat...A preliminary study was conducted to outline the laser Raman spectroscopy technique for determination of salinity in the aqueous phase in fluid inclusions. The skewing parameters of the Raman profiles of the calibration solutions determined were used to derive a calibration curve for the estimation of the equivalent mass fraction NaCl in aqueous solutions. This technique was also verified in the analysis of the natural fluid inclusions from Tongshankou porphyry Cu (Mo) deposit, Hubei Province, China. Although the analyses on the natural fluid inclusions are limited, an acceptable agreement has been reached on the salinities, for most fluid inclusions, determined by the Raman spectroscopy and microthermometry techniques, indicating the reliability of the Raman technique for determination of salinity in fluid inclusion studies.展开更多
基金supported by the grants from the National Natural Science Foundation of China (31270330, 91217310, 91017008 and 31171389)the National Basic Research Program of China (2014CB943400)+2 种基金the National Key Research and Development Program of China (2016YFD0100402)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA0801010402)the One-Hundred Talent Project of the Chinese Academy of Sciences to Y.C
文摘AGC protein kinases play important roles in plant growth and development.Several AGC kinases in Arabidopsis have been functionally characterized.However,the"AGC Other"subfamily,including IRE,IREH1,IRE3 and IRE4,has not been well understood.Here,we reported that ireh1 mutants displayed a root skewing phenotype,which can be enhanced by ire3 mutation.IREH1 and IRE3 were expressed in roots,consistent with their function in controlling root skewing.The fluorescence intensities of the microtubule marker KNpro:EGFP-MBD were decreased in ireh1,ire3 and ireh1 ire3 mutants compared to wild type.The microtubule arrangements in ireh1 and ireh1 ire3 mutants were also altered.IREH1 physically interacted with IRE3 in vitro and in planta.Thus,our findings demonstrate that IREH1 and IRE3 protein kinases play important roles in controlling root skewing,and maintaining microtubule network in Arabidopsis.
基金supported by the National Natural Science Foundation of China(No.11402010)
文摘When the wing of Oblique Wing Aircraft(OWA)is skewed,the center of gravity,inertia and aerodynamic characteristics of the aircraft all significantly change,causing an undesirable flight dynamic response,affecting the flying qualities,and even endangering the flight safety.In this study,the dynamic response of an OWA in the wing skewing process is simulated,showing that the threeaxis movements of the OWA are highly coupled and present nonlinear characteristics during the wing skewing.As the roll control efficiency of the aileron decreases due to the shortened control arm in an oblique configuration,the all-moving horizontal tail is used for additional roll and the control allocation is performed based on minimum control energy.Given the properties of pitchroll-yaw coupling and control input and state coupling,and the difficulty of establishing an accurate aerodynamic model in the wing skewing process due to unsteady aerodynamic force,a multi-loop sliding mode controller is formulated by the time-scale separation method.The closed-loop simulation results show that the asymmetric aerodynamics can be balanced and that the velocity and altitude of the aircraft maintain stable,which means that a smooth transition is obtained during the OWA's wing skewing.
文摘Double Sided Linear Synchronous Reluctance Motors(DSL-SynRM)are being increasingly used in high force density applications.The force ripples are one of the major issue in machine which is due to nonlinear nature of current in the machines.This paper focuses on the reduction of force ripples for increasing the force density of the motor.In order to reduce the force ripples,DSL-SynRM with a skewed translator is proposed.The proposed structure is designed and developed by using computational magnetic tools.This concept is effective for reduction of the force ripples and improves the force density of the machine.The proposed design has been reduced the percentage of force ripples by 21.62%,improved the force density by 10.32 N/mm³and efficiency by 0.89%.
文摘Evaluating the adversarial robustness of classification algorithms in machine learning is a crucial domain.However,current methods lack measurable and interpretable metrics.To address this issue,this paper introduces a visual evaluation index named confidence centroid skewing quadrilateral,which is based on a classification confidence-based confusion matrix,offering a quantitative and visual comparison of the adversarial robustness among different classification algorithms,and enhances intuitiveness and interpretability of attack impacts.We first conduct a validity test and sensitive analysis of the method.Then,prove its effectiveness through the experiments of five classification algorithms including artificial neural network(ANN),logistic regression(LR),support vector machine(SVM),convolutional neural network(CNN)and transformer against three adversarial attacks such as fast gradient sign method(FGSM),DeepFool,and projected gradient descent(PGD)attack.
基金supported by the National Natural Science Foundation of China(Grant No.51675324)
文摘In this paper, a multi-physics simulation model capable of electromagnetic noise prediction is established, and the effectiveness of the established simulation model in predicting and evaluating electromagnetic noise is verified. Based on the verified motor model, a rotor step skewing model which can affect electromagnetic noise is proposed, and the influence of the skewing angle on electromagnetic noise is investigated in detail. By studying the spectral characteristics of the low-order radial magnetic force which has a great influence on electromagnetic noise, the distribution of electromagnetic noise characteristics of the permanent magnet synchronous motor(PMSM) with or without the rotor step skewing is compared and analyzed. Therefore, it lays a technological foundation for predicting and suppressing the electromagnetic vibration noise of electric vehicle(EV) driving motor in the electromagnetic design.
基金support of the National Natural Science Foundation of China (Nos. 51675120 and U1637206)
文摘In this paper, an equation for the calculation of the frictional torque of a dry-lubricated tapered roller bearing(TRB) is provided in which the effect of the roller skewing is emphasized. Calculations were performed to investigate the effect of the roller skewing on the torque of dry-lubricated TRB for two representative preload methods, that is, axial force preload and axial displacement preload. The results show that a proper roller skewing angle under axial force preload benefits the reduction of the TRB torque. However, the roller skewing angle should not exceed a certain critical value;otherwise, it will cause a steep rise in the TRB torque. Finally, the critical value of the roller skewing angle as a function of the friction coefficient and cage pocket clearance is presented. The developed torque model provides a tool for the internal design and torque optimization of dry-lubricated TRBs.
基金funded by National Natural Science Foundation of China(32171533 and 31971444)Anhui Provincial Natural Science Foundation(2208085J28).
文摘Seed dispersal is a pivotal process in seed plant life cycle,owing to its effects on seed germination,seedling survival,population recruitment,and diversity maintenance in the entire community(Howe and Smallwood,1982;Rogers et al.,2021).There are diverse dispersal modes,such as anemochory(wind-driven dispersal),hydrochory(water-mediated dispersal),autochory(self-dispersal),and zoochory,which relies on a diverse array of animals for seed dispersal(Howe and Smallwood,1982).It is widely known that these varying dispersal modes impose selective pressures on many seed and fruit traits,especially the seed size,a key trait which is associated with multiple stages of the life cycle of plants,such as dispersal,germination,and establishment,particularly during early development(Leishman et al.,2000).
文摘We use transaction-level data from the Bitcoin exchange Mt.Gox,including over 1.4 million transactions from more than 45,000 traders,to investigate the role of technical chart patterns in the early Bitcoin market from April 2011 to September 2013.Employing a pattern recognition algorithm,we identify hourly trading signals for five major chart patterns.Buy signals of these patterns are associated with an average increase in abnormal trading volume of more than 53%.Trades executed during buy signal periods yield significantly higher average returns than those made during non-signal periods.Traders who use chart patterns more frequently are more likely to generate right-skewed return distributions,engage in more active trading,and achieve higher average roundtrip returns.Our research suggests that chart pattern trading was a crucial tool for Mt.Gox clients,highlighting the importance of technical heuristics in shaping the dynamics in a less efficient and unregulated market environment.By leveraging a comprehensive transaction dataset from a major cryptocurrency exchange,we provide unique insights into the actual trading behavior of the first Bitcoin adopters.This sets our work apart from previous studies that mainly rely on backtesting technical strategies using publicly available price data.
文摘In this study,we propose a Gram-Charlier expansion approach to investigate the impact of skewness and kurtosis on production and hedging decisions.Consistent with the existing literature,we find that skewness and kurtosis do not affect decisions regarding optimal production;however,they significantly influence optimal hedging decisions.We observe that positive skewness with platykurtic spot prices or negative skewness with leptokurtic spot prices often leads to over-hedging when the initial forward contract price exceeds its expected value.Conversely,under-hedging is expected when the initial forward contract price falls below its expected value.In other conditions,skewness can either promote or impede speculative future trading.Using the Gram-Charlier expansion of the spot price density function,we find that optimal future positions depend on forward prices,the hedgers’risk preference,and the spot price distribution.Simulations validate our findings on the impact of skewness and kurtosis on future hedging.Finally,we analyze of a cotton storage and forward contracting dataset to illustrate the application of our methodology and support our theoretical results.
文摘Heart failure prediction is crucial as cardiovascular diseases become the leading cause of death worldwide,exacerbated by the COVID-19 pandemic.Age,cholesterol,and blood pressure datasets are becoming inadequate because they cannot capture the complexity of emerging health indicators.These high-dimensional and heterogeneous datasets make traditional machine learning methods difficult,and Skewness and other new biomarkers and psychosocial factors bias the model’s heart health prediction across diverse patient profiles.Modern medical datasets’complexity and high dimensionality challenge traditional predictionmodels like SupportVectorMachines and Decision Trees.Quantum approaches include QSVM,QkNN,QDT,and others.These Constraints drove research.The“QHF-CS:Quantum-Enhanced Heart Failure Prediction using Quantum CNN with Optimized Feature Qubit Selection with Cuckoo Search in Skewed Clinical Data”system was developed in this research.This novel system leverages a Quantum Convolutional Neural Network(QCNN)-based quantum circuit,enhanced by meta-heuristic algorithms—Cuckoo SearchOptimization(CSO),Artificial BeeColony(ABC),and Particle SwarmOptimization(PSO)—for feature qubit selection.Among these,CSO demonstrated superior performance by consistently identifying the most optimal and least skewed feature subsets,which were then encoded into quantum states for circuit construction.By integrating advanced quantum circuit feature maps like ZZFeatureMap,RealAmplitudes,and EfficientSU2,the QHF-CS model efficiently processes complex,high-dimensional data,capturing intricate patterns that classical models overlook.The QHF-CS model improves precision,recall,F1-score,and accuracy to 0.94,0.95,0.94,and 0.94.Quantum computing could revolutionize heart failure diagnostics by improving model accuracy and computational efficiency,enabling complex healthcare diagnostic breakthroughs.
基金supported by the National Natural Science Foundation of China(Grant Nos.12473001,11975072,11875102,11835009,and 11965013)the National SKA Program of China(Grant Nos.2022SKA0110200 and 2022SKA0110203)+1 种基金the National 111 Project(Grant No.B16009)supported by Yunnan High-level Talent Training Support Plan Young&Elite Talents Project(Grant No.YNWR-QNBJ-2018-181).
文摘The comprehension of universal thermodynamic behaviors in the supercritical region is crucial for examining the characteristics of black hole systems under high temperature and pressure.This study is devoted to the analysis of characteristic lines and crossover behaviors within the supercritical region.By making use of the free energy,we introduce three key thermodynamic quantities:scaled variance,skewness,and kurtosis.Our results demonstrate that the Widom line,associated with the maximal scaled variance,can effectively differentiate between small and large black hole-like subphases,each displaying distinct thermodynamic behaviors within the supercritical region.Furthermore,by utilizing quasinormal modes,we identify the Frenkel line,offering a dynamic perspective to distinguish between small and large black hole-like subphases.These contribute to a deeper comprehension of black hole subphases in the supercritical region,thus illuminating new facets of black hole thermodynamics.
基金The National Natural Science Foundation of China(No.51009144)
文摘Regarding the scale effects on propeller＇s noncavitation hydrodynamics and hydroacoustics, three similar 7bladed highly-skewed propellers in the wake flow are addressed with diameters of 250, 500 and 1 000 mm, respectively. The discrete line-spectrum noise and its standardized spectrum level scaling law, together with the total sound pressure level are analyzed. The non-cavitation noise predictions are completed by both the frequency domain method and the time domain method. As a fluctuated noise source, the time-dependent fluctuated pressure and normal velocity distribution on propeller blades are obtained by the unsteady Reynolds-averaged Navier-Stokes （ URANS ） simulation. Results show that the pressure coefficient distribution of three propellers on the 0.7R section is nearly superposed under the same advance ratio. The periodic thrust fluctuation of three propellers can exactly reflect the tonal components of the axial passing frequency （APF） and the blade passing frequency （BPF）, and the fluctuation enhancement from the small to the middle propeller at the BPF is greater than that from the middle to the big one. By the two noise prediction methods, the increment of the total sound pressure level from the small to the big propeller differs by 2.49 dB. Following the standardized scaling law, the spectrum curves of the middle and big propellers are nearly the same while significantly differing from the small one. The increment of both the line-spectrum level and the total sound pressure increases with the increase in diameter. It is suggested that the model scale of the propeller should be as large as possible in engineering to reduce the prediction error of the empirical scalin~ law and weaken the scale effects.
文摘A preliminary study was conducted to outline the laser Raman spectroscopy technique for determination of salinity in the aqueous phase in fluid inclusions. The skewing parameters of the Raman profiles of the calibration solutions determined were used to derive a calibration curve for the estimation of the equivalent mass fraction NaCl in aqueous solutions. This technique was also verified in the analysis of the natural fluid inclusions from Tongshankou porphyry Cu (Mo) deposit, Hubei Province, China. Although the analyses on the natural fluid inclusions are limited, an acceptable agreement has been reached on the salinities, for most fluid inclusions, determined by the Raman spectroscopy and microthermometry techniques, indicating the reliability of the Raman technique for determination of salinity in fluid inclusion studies.
