Two automatic measurement methods of bidirectional reflection distribution function （BRDF） are presented based on absolute and relative definition. Measurement principle and scheme of the methods are analyzed. A rea...Two automatic measurement methods of bidirectional reflection distribution function （BRDF） are presented based on absolute and relative definition. Measurement principle and scheme of the methods are analyzed. A real-time measurement device is developed, the measurement spectral range of which is from ultraviolet to near infrared with 2.4-nm wavelength resolution, and the angular range is 0° - 360° in azimuth angle and 0° - 85° in zenith angle with 0.01° angle resolution. Absolute measurements of BRDF on tinfoil and ceramic tile are performed and the test materials present apparent specular reflection characteristics. The theoretical error in the experiment is about 6.05%. The BRDF measurement results are closely related to the precision of measurement platform, the sensitivity of measurement instrument, and the stability of illuminating light source.展开更多
The average bit error rate （BER） performance of a free-space optical （FOS） system based on the multi-hop parallel decode-and-forward cooperative communication method with an M-ary phase shift keying subcarrier int...The average bit error rate （BER） performance of a free-space optical （FOS） system based on the multi-hop parallel decode-and-forward cooperative communication method with an M-ary phase shift keying subcarrier intensity modulation is studied systematically. With the max-min criterion as the best path selection scheme, the probability density function and the cumulative distribution function of the gamma-gamma distribution random variable signal-to-noise ratio are derived. The analytical BER expression is then obtained in terms of the Gauss-Laguerre quadrature rule. Monte Carlo simulation is also provided to confirm the validity of the presented average BER model.展开更多
This paper describes the development and application of a new mathematical technique to include stochasticity in environmental models. The techniques are studied to develop stochastic analysis model of the CBOD NBOD D...This paper describes the development and application of a new mathematical technique to include stochasticity in environmental models. The techniques are studied to develop stochastic analysis model of the CBOD NBOD DO equations for predicting the river water quality. The CBOD NBOD DO equations are expanded to include stochastic terms. Stochastic terms are separated from non fluctuating terms, and the resulting set of equations is solved simultaneously. Solutions are used to calculating the integral solutions and the distribution moments of the state variables. The moments are used in conjunction with the Fokker Planck equation to produce an analytical solution for the probability density functions of the dependent variables. Because the approach produces analytical solutions, it offers greater flexibility than a Monte Carlo approach in treating complex environmental situations. The model is used to calculate water quality for the Qingao river. The calculated results are in good agreement with the Monte Carlo model and field data.展开更多
The probability density functions (pdf’s) and the first order structure functions (SF’s) of the pairwise Euclidean distances between scaled multichannel human EEG signals at different time lags under hypoxia and in ...The probability density functions (pdf’s) and the first order structure functions (SF’s) of the pairwise Euclidean distances between scaled multichannel human EEG signals at different time lags under hypoxia and in resting state at different ages are estimated. It is found that the hyper gamma distribution is a good fit for the empirically derived pdf in all cases. It means that only two parameters (sample mean of EEG Euclidean distances at a given time lag and relevant coefficient of variation) may be used in the approximate classification of empirical pdf’s. Both these parameters tend to increase in the first twenty years of life and tend to decrease as healthy adults getting older. Our findings indicate that such age-related dependence of these parameters looks like as age- related dependence of the total brain white matter volume. It is shown that 15 min hypoxia (8% oxygen in nitrogen) causes a significant (about 50%) decrease of the mean relative displacement EEG value that is typical for the rest state. In some sense the impact of the oxygen deficit looks like the subject getting older during short-term period.展开更多
Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in...Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in NaC1 and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g （0.012 7 tool）, 8 g （0.025 4 mol） and 6 g （0.019 l tool） NaaCr207 exhibited, in that order, high inhibition effectiveness, with respective efficiency, r/, of （90.46±1.30）%, （88.41＋2.24）% and （84.87±4.74）%, in the NaC1 medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g （0.025 4 mol） Na2Cr207 concentration having r/=（78.44±1.10）%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.展开更多
We have applied the Lie-Trotter operator splitting method to model the dynamics of both the sum and difference of two correlated constant elasticity of variance (CEV) stochastic variables. Within the Lie-Trotter split...We have applied the Lie-Trotter operator splitting method to model the dynamics of both the sum and difference of two correlated constant elasticity of variance (CEV) stochastic variables. Within the Lie-Trotter splitting approximation, both the sum and difference are shown to follow a shifted CEV stochastic process, and approximate probability distributions are determined in closed form. Illustrative numerical examples are presented to demonstrate the validity and accuracy of these approximate distributions. These approximate probability distributions can be used to valuate two-asset options, e.g. spread options and basket options, where the CEV variables represent the forward prices of the underlying assets. Moreover, we believe that this new approach can be extended to study the algebraic sum of N CEV variables with potential applications in pricing multi-asset options.展开更多
基金supported by the National"863"Project of China under Grant No.2006AA704214-5.
文摘Two automatic measurement methods of bidirectional reflection distribution function （BRDF） are presented based on absolute and relative definition. Measurement principle and scheme of the methods are analyzed. A real-time measurement device is developed, the measurement spectral range of which is from ultraviolet to near infrared with 2.4-nm wavelength resolution, and the angular range is 0° - 360° in azimuth angle and 0° - 85° in zenith angle with 0.01° angle resolution. Absolute measurements of BRDF on tinfoil and ceramic tile are performed and the test materials present apparent specular reflection characteristics. The theoretical error in the experiment is about 6.05%. The BRDF measurement results are closely related to the precision of measurement platform, the sensitivity of measurement instrument, and the stability of illuminating light source.
基金supported by the National Natural Science Foundation of China(No.61474090)the Natural Science Basic Research Plan in Shaanxi Province of China(No.2014JM8340)+3 种基金the China Postdoctoral Science Special Foundation(No.201104659)the China Postdoctoral Science Foundation(No.20100481322)the Fundamental Research Funds for the Central Universities(No.NSIY041404)supported by the 111 Project of China(No.B08038)
文摘The average bit error rate （BER） performance of a free-space optical （FOS） system based on the multi-hop parallel decode-and-forward cooperative communication method with an M-ary phase shift keying subcarrier intensity modulation is studied systematically. With the max-min criterion as the best path selection scheme, the probability density function and the cumulative distribution function of the gamma-gamma distribution random variable signal-to-noise ratio are derived. The analytical BER expression is then obtained in terms of the Gauss-Laguerre quadrature rule. Monte Carlo simulation is also provided to confirm the validity of the presented average BER model.
文摘This paper describes the development and application of a new mathematical technique to include stochasticity in environmental models. The techniques are studied to develop stochastic analysis model of the CBOD NBOD DO equations for predicting the river water quality. The CBOD NBOD DO equations are expanded to include stochastic terms. Stochastic terms are separated from non fluctuating terms, and the resulting set of equations is solved simultaneously. Solutions are used to calculating the integral solutions and the distribution moments of the state variables. The moments are used in conjunction with the Fokker Planck equation to produce an analytical solution for the probability density functions of the dependent variables. Because the approach produces analytical solutions, it offers greater flexibility than a Monte Carlo approach in treating complex environmental situations. The model is used to calculate water quality for the Qingao river. The calculated results are in good agreement with the Monte Carlo model and field data.
文摘The probability density functions (pdf’s) and the first order structure functions (SF’s) of the pairwise Euclidean distances between scaled multichannel human EEG signals at different time lags under hypoxia and in resting state at different ages are estimated. It is found that the hyper gamma distribution is a good fit for the empirically derived pdf in all cases. It means that only two parameters (sample mean of EEG Euclidean distances at a given time lag and relevant coefficient of variation) may be used in the approximate classification of empirical pdf’s. Both these parameters tend to increase in the first twenty years of life and tend to decrease as healthy adults getting older. Our findings indicate that such age-related dependence of these parameters looks like as age- related dependence of the total brain white matter volume. It is shown that 15 min hypoxia (8% oxygen in nitrogen) causes a significant (about 50%) decrease of the mean relative displacement EEG value that is typical for the rest state. In some sense the impact of the oxygen deficit looks like the subject getting older during short-term period.
文摘Corrosion test data were measured using non-destructive electrochemical techniques and analysed for studying inhibition effectiveness by different concentrations of NazCr207 on the corrosion of concrete steel-rehar in NaC1 and in H2SO4 media. For these, specifications of ASTM G16-95 R04 were combined with the normal and the Gumbel probability density functions as model analytical methods for addressing issues of conflicting reports of inhibitor effectiveness that had generated concerns. Results show that reinforced concrete samples admixed with concentrations having 4 g （0.012 7 tool）, 8 g （0.025 4 mol） and 6 g （0.019 l tool） NaaCr207 exhibited, in that order, high inhibition effectiveness, with respective efficiency, r/, of （90.46±1.30）%, （88.41＋2.24）% and （84.87±4.74）%, in the NaC1 medium. These exhibit good agreements within replicates and statistical methods for the samples. Also, optimal inhibition effectiveness model in the H2SO4 medium was exhibited by 8 g （0.025 4 mol） Na2Cr207 concentration having r/=（78.44±1.10）%. These bear implications for addressing conflicting test data in the study of effective inhibitors for mitigating steel-rebar corrosion in aggressive environments.
文摘We have applied the Lie-Trotter operator splitting method to model the dynamics of both the sum and difference of two correlated constant elasticity of variance (CEV) stochastic variables. Within the Lie-Trotter splitting approximation, both the sum and difference are shown to follow a shifted CEV stochastic process, and approximate probability distributions are determined in closed form. Illustrative numerical examples are presented to demonstrate the validity and accuracy of these approximate distributions. These approximate probability distributions can be used to valuate two-asset options, e.g. spread options and basket options, where the CEV variables represent the forward prices of the underlying assets. Moreover, we believe that this new approach can be extended to study the algebraic sum of N CEV variables with potential applications in pricing multi-asset options.
