The objective of the current study is to investigate the importance of entropy generation and thermal radiation on the patterns of velocity,isentropic lines,and temperature contours within a thermal energy storage dev...The objective of the current study is to investigate the importance of entropy generation and thermal radiation on the patterns of velocity,isentropic lines,and temperature contours within a thermal energy storage device filled with magnetic nanoencapsulated phase change materials(NEPCMs).The versatile finite element method(FEM)is implemented to numerically solve the governing equations.The effects of various parameters,including the viscosity parameter,ranging from 1 to 3,the thermal conductivity parameter,ranging from 1 to 3,the Rayleigh parameter,ranging from 102 to 3×10^(2),the radiation number,ranging from 0.1 to 0.5,the fusion temperature,ranging from 1.0 to 1.2,the volume fraction of NEPCMs,ranging from 2%to 6%,the Stefan number,ranging from 1 to 5,the magnetic number,ranging from 0.1 to 0.5,and the irreversibility parameter,ranging from 0.1 to 0.5,are examined in detail on the temperature contours,isentropic lines,heat capacity ratio,and velocity fields.Furthermore,the heat transfer rates at both the cold and hot walls are analyzed,and the findings are presented graphically.The results indicate that the time taken by the NEPCMs to transition from solid to liquid is prolonged inside the chamber region as the fusion temperatureθf increases.Additionally,the contours of the heat capacity ratio Cr decrease with the increase in the Stefan number Ste.展开更多
Desert plants take on unique physiologically adaptive mechanisms in response to an adverse environment. In this study, we determined the concentrations of leaf nitrogen(N), phosphorus(P), and calcium(Ca) fraction for ...Desert plants take on unique physiologically adaptive mechanisms in response to an adverse environment. In this study, we determined the concentrations of leaf nitrogen(N), phosphorus(P), and calcium(Ca) fraction for dominant species of Artemisia ordosica, A. frigida, Calligonum mongolicum, and Oxytropis aciphylla in the Alxa Desert and discussed seasonal changes of their leaf N:P ratio and Ca fraction. The results showed that, from May to September, the N:P ratios of A. ordosica and C. mongolicum gradually and significantly increased, while those of A. frigida, and O. aciphylla had an increase trend that was not significant; the physiologically active Ca of A. ordosica and A. frigida increased significantly,while that of C. mongolicum and O. aciphylla decreased significantly. The physiologically inert calcium of C. mongolicum increased extremely significantly, while that of others was not significant. There was a significantly positive correlation between the N:P ratio and physiologically active Ca for A. ordosica, and the N:P ratio was significantly and negatively correlated with physiologically active Ca for O. aciphylla. These findings revealed that the physiological regulation mechanism was different for the plants either in earlier stage or later stage of plant-community succession.展开更多
As a combination device for a step-up pulse transformer and a magnetic switch,the saturable pulse transformer is widely used in pulsed-power and plasma technology.A fractional-turn ratio saturable pulse transformer is...As a combination device for a step-up pulse transformer and a magnetic switch,the saturable pulse transformer is widely used in pulsed-power and plasma technology.A fractional-turn ratio saturable pulse transformer is constructed and analyzed in this paper.Preliminary experimental results show that if the primary energy storage capacitors are charged to 300 V,an output voltage of about 19 kV can be obtained across the capacitor connected to the secondary windings of a fractional-tum ratio saturable pulse transformer.Theoretical and experimental results reveal that this kind of pulse transformer is not only able to integrate a step-up transformer and a magnetic switch into one device,but can also lower the saturable inductance of its secondary windings,thus leading to the relatively high step-up ratio of the pulse transformer.Meanwhile,the application of the fractional-turn ratio saturable pulse transformer in a μs range pulse modulator as a voltage step-up device and main switch is also included in this paper.The demonstrated experiments display that an output voltage with an amplitude of about 29 kV,and a 1.6 μs pulse width can be obtained across a 3500 Ω resistive load,based on a pulse modulator,if the primary energy storage capacitors are charged to 300 V.This compact fractional-turn ratio saturable pulse transformer can be applied in many other fields such as surface treatment,corona plasma generation and dielectric barrier discharge.展开更多
This paper studies the insurer’s solvency ratio model in a class of mixed fractional Brownian motion(MFBM) market, where the prices of assets follow a Wick-It? stochastic differential equation driven by the MFBM, by ...This paper studies the insurer’s solvency ratio model in a class of mixed fractional Brownian motion(MFBM) market, where the prices of assets follow a Wick-It? stochastic differential equation driven by the MFBM, by the method of the stochastic calculus of the MFBM and the pricing formula of European call option for the MFBM, the explicit formula for the expected present value of shareholders’ terminal payoff is given. The model extends the existing results.展开更多
The insurer's solvency ratio model in a class of fractional Black-Scholes markets is studied. In this market,the price of assets follows a Wick-It stochastic differential equation,which is driven by the fraction...The insurer's solvency ratio model in a class of fractional Black-Scholes markets is studied. In this market,the price of assets follows a Wick-It stochastic differential equation,which is driven by the fractional Brownian motion. The market coefficients of market model are deterministic functions. By the stochastic calculus of the fractional Brownian motion and the pricing formula of European call option for the fractional Brownian motion,the explicit formula for the expected present value of shareholder's terminal payoff is given. The model extends the existing results.展开更多
Hemodynamical evaluation of a coronary artery lesion is an important diagnostic step to assess its functional impact.Fractional flow reserve(FFR)received a class IA recommendation from the European Society of Cardiolo...Hemodynamical evaluation of a coronary artery lesion is an important diagnostic step to assess its functional impact.Fractional flow reserve(FFR)received a class IA recommendation from the European Society of Cardiology for the assessment of angiographically moderate stenosis.FFR evaluation of coronary artery disease offers improvement of the therapeutic strategy,deferring unnecessary procedures for lesions with a FFR>0.8,improving patients'management and clinical outcome.Post intervention,an optimal FFR>0.9 post stenting should be reached and>0.8 post drug eluting balloons.Non-hyperemic pressure ratio measurements have been validated in previous studies with a common threshold of 0.89.They might overestimate the hemodynamic significance of some lesions but remain useful whenever hyperemic agents are contraindicated.FFR remains the gold standard reference for invasive assessment of ischemia.We illustrate this review with two cases introducing the possibility to estimate also non-invasively FFR from reconstructed 3-D angiograms by quantitative flow ratio.We conclude introducing a hybrid approach to intermediate lesions(DFR 0.85-0.95)potentially maximizing clinical decision from all measurements.展开更多
New non-and less-invasive techniques have been developed to overcome the procedural and operator related burden of the fractional flow reserve(FFR)for the assessment of potentially significant stenosis in the coronary...New non-and less-invasive techniques have been developed to overcome the procedural and operator related burden of the fractional flow reserve(FFR)for the assessment of potentially significant stenosis in the coronary arteries.Virtual FFR-techniques can obviate the need for the additional flow or pressure wires as used for FFR measurements.This review provides an overview of the developments and validation of the virtual FFR-algorithms,states the challenges,discusses the upcoming clinical trials,and postulates the future role of virtual FFR in the clinical practice.展开更多
Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the cas...Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the case of the availability of reliable, express, and cheap methods, the area of their use will gradually expand. A determination of the atomic fraction of the isotopes carbon-13 and nitrogen-15 directly in glycine, leucine, isoleucine, and alanine is proposed;the modification concerns all centers or one or more identical carbon and nitrogen centers separately, as well as both isotopes at the same time. There are defined mass lines of the mass spectrum of each amino acid, through which the isotopic content of carbon and nitrogen is calculated. The processes that must be taken into account for the determination of the isotopic content are also established. Isotopic analysis of these compounds until now was carried out by transforming them into carbon oxide, dioxide, and molecular nitrogen, and determination of their content in individual centers was impossible.展开更多
Fractional factorial split-plot design has been widely used in many fields due to its advantage of saving experimental cost. The general minimum lower order confounding criterion is usually used as one of the attracti...Fractional factorial split-plot design has been widely used in many fields due to its advantage of saving experimental cost. The general minimum lower order confounding criterion is usually used as one of the attractive design criterion for selecting fractional factorial split-plot design. In this paper, we are interested in the theoretical construction methods of the optimal fractional factorial split-plot designs under the general minimum lower order confounding criterion. We present the theoretical construction methods of optimal fractional factorial split-plot designs under general minimum lower order confounding criterion under several conditions.展开更多
基于分数阶傅里叶变换(Fractional Fourier Transform,FRFT)对线性调频(Linear Frequency Modulated,LFM)信号参数进行估计,问题关键是确定FRFT最佳阶数,根据误差迭代思想提出新的参数估计算法,该算法利用归一化带宽和旋转角的转化关系...基于分数阶傅里叶变换(Fractional Fourier Transform,FRFT)对线性调频(Linear Frequency Modulated,LFM)信号参数进行估计,问题关键是确定FRFT最佳阶数,根据误差迭代思想提出新的参数估计算法,该算法利用归一化带宽和旋转角的转化关系,由估计误差推算角度差值,有效降低了运算量,不需要调频斜率正负的先验信息,改进的对数搜索算法可以进一步提高参数估计结果的稳定性和可靠性。仿真结果表明,信噪比在-8 dB以上时该方法在高效率的前提下仍具有良好的参数估计性能,平均估计误差在1%以内,估计结果接近Cramer-Rao下限,满足工程实时处理需求。展开更多
文摘The objective of the current study is to investigate the importance of entropy generation and thermal radiation on the patterns of velocity,isentropic lines,and temperature contours within a thermal energy storage device filled with magnetic nanoencapsulated phase change materials(NEPCMs).The versatile finite element method(FEM)is implemented to numerically solve the governing equations.The effects of various parameters,including the viscosity parameter,ranging from 1 to 3,the thermal conductivity parameter,ranging from 1 to 3,the Rayleigh parameter,ranging from 102 to 3×10^(2),the radiation number,ranging from 0.1 to 0.5,the fusion temperature,ranging from 1.0 to 1.2,the volume fraction of NEPCMs,ranging from 2%to 6%,the Stefan number,ranging from 1 to 5,the magnetic number,ranging from 0.1 to 0.5,and the irreversibility parameter,ranging from 0.1 to 0.5,are examined in detail on the temperature contours,isentropic lines,heat capacity ratio,and velocity fields.Furthermore,the heat transfer rates at both the cold and hot walls are analyzed,and the findings are presented graphically.The results indicate that the time taken by the NEPCMs to transition from solid to liquid is prolonged inside the chamber region as the fusion temperatureθf increases.Additionally,the contours of the heat capacity ratio Cr decrease with the increase in the Stefan number Ste.
基金supported by the National Key R&D Program of China (2016YFC0500706)
文摘Desert plants take on unique physiologically adaptive mechanisms in response to an adverse environment. In this study, we determined the concentrations of leaf nitrogen(N), phosphorus(P), and calcium(Ca) fraction for dominant species of Artemisia ordosica, A. frigida, Calligonum mongolicum, and Oxytropis aciphylla in the Alxa Desert and discussed seasonal changes of their leaf N:P ratio and Ca fraction. The results showed that, from May to September, the N:P ratios of A. ordosica and C. mongolicum gradually and significantly increased, while those of A. frigida, and O. aciphylla had an increase trend that was not significant; the physiologically active Ca of A. ordosica and A. frigida increased significantly,while that of C. mongolicum and O. aciphylla decreased significantly. The physiologically inert calcium of C. mongolicum increased extremely significantly, while that of others was not significant. There was a significantly positive correlation between the N:P ratio and physiologically active Ca for A. ordosica, and the N:P ratio was significantly and negatively correlated with physiologically active Ca for O. aciphylla. These findings revealed that the physiological regulation mechanism was different for the plants either in earlier stage or later stage of plant-community succession.
基金supported by National Natural Science Foundation of China under Grant Nos.51477177 and 51641707
文摘As a combination device for a step-up pulse transformer and a magnetic switch,the saturable pulse transformer is widely used in pulsed-power and plasma technology.A fractional-turn ratio saturable pulse transformer is constructed and analyzed in this paper.Preliminary experimental results show that if the primary energy storage capacitors are charged to 300 V,an output voltage of about 19 kV can be obtained across the capacitor connected to the secondary windings of a fractional-tum ratio saturable pulse transformer.Theoretical and experimental results reveal that this kind of pulse transformer is not only able to integrate a step-up transformer and a magnetic switch into one device,but can also lower the saturable inductance of its secondary windings,thus leading to the relatively high step-up ratio of the pulse transformer.Meanwhile,the application of the fractional-turn ratio saturable pulse transformer in a μs range pulse modulator as a voltage step-up device and main switch is also included in this paper.The demonstrated experiments display that an output voltage with an amplitude of about 29 kV,and a 1.6 μs pulse width can be obtained across a 3500 Ω resistive load,based on a pulse modulator,if the primary energy storage capacitors are charged to 300 V.This compact fractional-turn ratio saturable pulse transformer can be applied in many other fields such as surface treatment,corona plasma generation and dielectric barrier discharge.
基金Supported by National Natural Science Foundation of China(71171003,71271003,and 11326121)Natural Science Foundation of Anhui Province(1508085MA02)+1 种基金Teaching Research Project of Anhui Province(2013jyxm111)Opening Project of Financial Engineering Research and Development Center of Anhui Polytechnic University(JRGCKF201502)
文摘This paper studies the insurer’s solvency ratio model in a class of mixed fractional Brownian motion(MFBM) market, where the prices of assets follow a Wick-It? stochastic differential equation driven by the MFBM, by the method of the stochastic calculus of the MFBM and the pricing formula of European call option for the MFBM, the explicit formula for the expected present value of shareholders’ terminal payoff is given. The model extends the existing results.
基金National Natural Science Foundations of China(Nos.71271003,71571001,11326121)Natural Science Foundation of Anhui Province,China(No.1608085M A02)+1 种基金Teaching Research Project of Anhui Province,China(No.2013jyxm111)Opening Project of Financial Engineering Research and Development Center of Anhui Polytechnic University,China(No.JRGCKF201502)
文摘The insurer's solvency ratio model in a class of fractional Black-Scholes markets is studied. In this market,the price of assets follows a Wick-It stochastic differential equation,which is driven by the fractional Brownian motion. The market coefficients of market model are deterministic functions. By the stochastic calculus of the fractional Brownian motion and the pricing formula of European call option for the fractional Brownian motion,the explicit formula for the expected present value of shareholder's terminal payoff is given. The model extends the existing results.
文摘Hemodynamical evaluation of a coronary artery lesion is an important diagnostic step to assess its functional impact.Fractional flow reserve(FFR)received a class IA recommendation from the European Society of Cardiology for the assessment of angiographically moderate stenosis.FFR evaluation of coronary artery disease offers improvement of the therapeutic strategy,deferring unnecessary procedures for lesions with a FFR>0.8,improving patients'management and clinical outcome.Post intervention,an optimal FFR>0.9 post stenting should be reached and>0.8 post drug eluting balloons.Non-hyperemic pressure ratio measurements have been validated in previous studies with a common threshold of 0.89.They might overestimate the hemodynamic significance of some lesions but remain useful whenever hyperemic agents are contraindicated.FFR remains the gold standard reference for invasive assessment of ischemia.We illustrate this review with two cases introducing the possibility to estimate also non-invasively FFR from reconstructed 3-D angiograms by quantitative flow ratio.We conclude introducing a hybrid approach to intermediate lesions(DFR 0.85-0.95)potentially maximizing clinical decision from all measurements.
文摘New non-and less-invasive techniques have been developed to overcome the procedural and operator related burden of the fractional flow reserve(FFR)for the assessment of potentially significant stenosis in the coronary arteries.Virtual FFR-techniques can obviate the need for the additional flow or pressure wires as used for FFR measurements.This review provides an overview of the developments and validation of the virtual FFR-algorithms,states the challenges,discusses the upcoming clinical trials,and postulates the future role of virtual FFR in the clinical practice.
文摘Using compounds modified by the isotopes carbon-13 and nitrogen-15 helps conduct research in various fields of science, such as medicine, pharmacology, pharmacokinetics, metabolism, agriculture, and others. In the case of the availability of reliable, express, and cheap methods, the area of their use will gradually expand. A determination of the atomic fraction of the isotopes carbon-13 and nitrogen-15 directly in glycine, leucine, isoleucine, and alanine is proposed;the modification concerns all centers or one or more identical carbon and nitrogen centers separately, as well as both isotopes at the same time. There are defined mass lines of the mass spectrum of each amino acid, through which the isotopic content of carbon and nitrogen is calculated. The processes that must be taken into account for the determination of the isotopic content are also established. Isotopic analysis of these compounds until now was carried out by transforming them into carbon oxide, dioxide, and molecular nitrogen, and determination of their content in individual centers was impossible.
文摘Fractional factorial split-plot design has been widely used in many fields due to its advantage of saving experimental cost. The general minimum lower order confounding criterion is usually used as one of the attractive design criterion for selecting fractional factorial split-plot design. In this paper, we are interested in the theoretical construction methods of the optimal fractional factorial split-plot designs under the general minimum lower order confounding criterion. We present the theoretical construction methods of optimal fractional factorial split-plot designs under general minimum lower order confounding criterion under several conditions.
