爱因斯坦A系数不是常参数

爱因斯坦引入A系数和B系数描述原子(或离子)的跃迁过程时,认为它们只与原子结构及跃迁能级有关,而与外界因素无关。近来Aumayr等人发现Ar^+激光场会使A系数产生改变。但是在他们的实验中可能存在的自吸收会影响结果的可靠性。我们改进了实验方法,采用准旁侧光谱法及空间滤波技术基本上消除了上述影响。 原子从同一上能级E向不同下能级E_i跃迁产生的自发辐射谱线强度为:

常参数下二选期权的定价

考虑常参数下基于收益率对数的二选较优看涨期权和二选较差看涨期权的定价,利用测度变换,将现实概率测度转化为风险中性概率测度,通过直接计算得到其解析定价公式.

包装机中塑料薄膜常热式热封参数的实验研究

文中通过对包装机中常热式热封过程的分析及有效的实验,获得较为可靠的热封实验数据,并利用专业统计软件spss对实验数据进行处理,得到包装机中塑料薄膜的封口强度与操作参数之间的关系,为设计人员提供了一种获得最优操作参数的有效方法。

广义流变体常Q模型表征参数反演

基于标准线性体的广义流变体模型提出了独立表征τ值法,以保证每个基本标准线性体具有独立的表征参数。该方法摒除了广义流变体模型中所有标准线性体具有相同松弛时间的不合理假设,解决了常规τ值拟合方法常Q值精度较低的问题。基于最速下降法的迭代反演求解算法提高了黏滞性表征参数精度。尤其是在天然地震和勘探开发地震频谱范围内,采用较少的标准线性体实现了常Q模型的高精度反演,对于大幅提高时间域黏弹性介质波动方程数值模拟计算效率具有重要意义。

常变动参数事件集合遵循Poison分布律的推证

本文从概率论的角度，推证了一种常变动参数的事件集合，在长度为τ的时间区间（ｔ，ｔ＋τ）内，遵循参变量Φ（τ，ｔ）的Ｐｏｉｓｏｎ分布律Ｖｋ（τ，ｔ）＝ｅ－Φ（τ，ｔ）〔Φ（τ，ｔ）〕ｋｋ！，ｋ＝０，１，２，…其中Φ（τ，ｔ）＝∫τ０λ（ｔ＋μ）ｄμ这一理论在实际运用中，可找到最佳方案值。

计量经济模型参数形式的演化与比较

在计量经济建模过程中,参数形式的确定是最基本的步骤。从经济学实证研究的实践看,计量经济建模中应用最早、应用最多的为常参数形式,上个世纪60年代以后,又逐步发展出变参数形式、非参数形式和半参数形式。经过一个多世纪的发展,四种参数形式已经形成了一个有着严密的传承关系的体系。各种参数形式既相互关联,又具有各自的优缺点,有着不同的应用领域,呈现出从简单到复杂逐步演进的特点,有着较强的发展规律性。

线性微分方程的通解

本文运用常参数变易法推导线性微分方程的通解公式,并利用通解公式求一些常用微分方程。

Robust PID controller design for time delay processes with peak of maximum sensitivity criteria

The motivation of this work is to obtain single PI/PID tuning formula for different types of processes with enhanced disturbance rejection performance. The proposed tuning formula consistently gives better performance in comparison to several well-known methods at the same degree of robustness for stable, integrating and unstable processes. For the selection of the closed-loop time constant(τc), a guideline is provided over a broad range of time-delay/time-constant ratios on the basis of the peak of maximum sensitivity(Ms). An analysis has been performed for the uncertainty margin with the different process parameters for the robust controller design. It gives the guideline of the Ms-value settings for the PI controller designs based on the process parameters uncertainty. Furthermore, a relationship has been developed between Ms-value and uncertainty margin with the different process parameters(k, τ and θ). Simulation study has been conducted for the broad class of processes and the controllers are tuned to have the same degree of robustness by measuring the maximum sensitivity, Ms, in order to obtain a reasonable comparison.

Normal Reference Value of Red Blood Cell Count of Chinese Presenile Men and Geographical Factors

This paper aims at providing a scientific basis for unifying the normal reference value standards of red blood cell count of Chinese presenile men. The paper, using microscopical counting method, studies the relationship between the normal reference values of 38,061 samples of red blood cell count of presenile men and eight geographical factors in 297 units in China. It is found that the correlation of geographical factors and the normal reference value of red blood cell count of presenile men is quite significant （F=303.00, P=-0.000）. By using the method of stepwise regression analysis, one regression equation is inferred. It is concluded that if geographical data are obtained in a certain area, the normal reference value of red blood cell count of presenile men in this area can be reckoned by using the regression analysis. Furthermore, according to the geographical factors, China can be divided into eight regions： Northeast China Region, North China Region, Shanxi-Shaanxi-Irmer Mongolia Region, Middle and Lower Reaches of the Changjiang River Region, Southeast China Region, Northwest China Region, Southwest China Region and Qinghai-Tibet Plateau Region.

Brightness Temperature Model of Sea Foam Layer at L-band

Permittivity of a sea foam layer is very important in investigating ocean brightness temperature model. At microwave frequency, the Rayleigh method is developed to estimate the effective permittivity of the sea foam layer. To simplify the tedious calculation of sea foam effective permittivity at L band （1.4GHz）, Pade＇ approximation is adopted to fit the sea foam effective permittivity computed by the Rayleigh method. With this fitting formula, a new brightness temperature model of sea foam layer defined by certain geophysical parameters, such as air volume fraction （AVF）, sea surface temperature （SST）, sea surface salinity （SSS） and thickness of foam layer d, is given. Furthermore, the sensitivities of the brightness temperature model to SST, SSS, d and AVF of a sea foam layer at L band are discussed. The sensitivities are ranked from most to least in the order： （1） d; （2） AVF; （3） SSS; （4） SST. This result indicates that the measurement errors old and AVF have significant impacts on the retrievals of SSS and SST. With the experimental brightness temperature data, the SSS and AFV are retrieved by cost function.

Effect of surface dissolution on kinetic parameters in flotation of ilmenite from different gangue minerals

The effects of acid surface dissolution on the flotation kinetics of ilmenite(IL)and its common accompanied gangue minerals including olivine-pyroxene(Ol-Px),tremolite-clinochlore(Tr-Cch)and quartz were investigated.The results show that through the surface dissolution the adsorption rate constant for ilmenite increases from 5.272 to 8.441 mol/(g·min)while it decreases for Ol-Px,Tr-Cch and quartz from 6.332,7.309 and 7.774 mol/(g·min)to 5.034,6.223 and 7.371 mol/(g·min),respectively.Also,the flotation experiments on a binary mixture of minerals indicate that after surface dissolution the values of modified rate constant for ilmenite flotation from Ol-Px,Tr-Cch and quartz are enhanced from 36.15,36.52 and 47.86 min-1 to 41.72,45.78 and 56.24 min-1,respectively.This results in the improvement of kinetic selectivity index(SI)in the separation of treated ilmenite from gangue minerals.As evidenced by ICP-MS analysis,the decrease of kinetic parameters for gangue minerals can be due to the removal of Fe^2+,Ca^2+and Mg^2+ions from their surfaces,which results in the lack of enough active sites to interact with collector species.As confirmed by contact angle measurements,this prevents the formation of a stable hydrophobic layer on the minerals surfaces for creating stable attachments between minerals and bubbles.Generally,the improvement of ilmenite flotation kinetics has a negative correlation with the iron content in its accompanied gangue minerals.

Uncertainty Study of B_d(B_s)→γv Decays

B^0(B+s)→γvv decays are useful to determining the decay constants f_B(f_B_s) and B(B_s) meson wavefunction.Using the B meson wave function determined in hadronic B(Bs) decays,we study the uncertainties due tothe types of B meson wave functions.We find that the branching ratios are sensitive to the type of wave functions andinput parameters,but the energy spectrum is independent.The predicted branching ratios are (0.45-1.04) ×10^(-9) and(2.14-3.27) × 10^(-8) for B^0 and B_s decay,respectively.

Petro-SIM模拟柴油凝点控制

介绍了中国石化济南炼化公司常减压装置在调整生产0#柴油时柴油凝点卡边控制遇到的困难,运用Petro-SIM软件对生产进行模拟,研究了原油油品性质及常压各操作参数对常三线柴油凝点的影响,结果表明:因受0#柴油95%馏出温度、中段取热量、汽油干点等参数的制约,在现有混输原油性质条件下难以实现常三线0#柴油凝点的卡边操作。

Experimental Study on Calculation of Hydro-Geological Parameters for Unsteady Flow

After the linear analytical method of unsteady flow theory is further improved,an innovative and faster algorithm is introduced.The water storage in a confined aquifer is derived from the water transmissivity coefficient and the water-pressure conductivity coefficient.The water transmissivity coefficient is approximated by a Taylorseries expansion of drawdown,and the water-pressure conductivity coefficient is obtained by the average drawdown.In this algorithm,the distance of the observation points from the pumping well must be short.When the distance is as short as the radius of the main pumping well,the data of the drawdown difference between the sidewall and the center of pumping well are difficult to measure,but the same results can be achieved based on the assumption that the drawdown difference approximates to the drawdown of the observation wells at a radial distance from the pumping well according to the algorithm.Without the help of charts,this algorithm is more concise and efficient,which has been verified by the test of water pumping project in Tianjin Binhai International Airport.

Prestack seismic stochastic inversion based on statistical characteristic parameters

In the conventional stochastic inversion method,the spatial structure information of underground strata is usually characterized by variograms.However,effectively characterizing the heterogeneity of complex strata is difficult.In this paper,multiple parameters are used to fully explore the underground formation information in the known seismic reflection and well log data.The spatial structure characteristics of complex underground reservoirs are described more comprehensively using multiple statistical characteristic parameters.We propose a prestack seismic stochastic inversion method based on prior information on statistical characteristic parameters.According to the random medium theory,this method obtains several statistical characteristic parameters from known seismic and logging data,constructs a prior information model that meets the spatial structure characteristics of the underground strata,and integrates multiparameter constraints into the likelihood function to construct the objective function.The very fast quantum annealing algorithm is used to optimize and update the objective function to obtain the fi nal inversion result.The model test shows that compared with the traditional prior information model construction method,the prior information model based on multiple parameters in this paper contains more detailed stratigraphic information,which can better describe complex underground reservoirs.A real data analysis shows that the stochastic inversion method proposed in this paper can effectively predict the geophysical characteristics of complex underground reservoirs and has a high resolution.

Structural and Dielectric Properties of Y_2O_3-Doped Ba_(0.92)Sr_(0.08)Ti_(0.95)Sn_(0.05)O_3 Ceramics

The structural and dielectric properties of Ba0.92Sr0.08Ti0.95Sn0.0503 （BSTS） ＋x（molar ratio, %） Y^3＋ceramics are investigated. Combining the lattice parameters and the distortion of crystal lattice, an alternation of substitution preference of Y^3＋ ion for the host cations in perovskite lattice is found. Owing to Y^3- ion entering the A site, the maximum dielectric constant is 5 627 for 1.25% Y^3＋-doped samples; when Y^3- ion is more than 1.25%, it tends to occupy the B site in perovskite lattice, causing a drop in the dielectric constant. Owing to the appearance of oxygen vacancy, the optimized dielectric loss is 0.004 for 1.25% Y^3＋-doped samples. The thermal stability of BSTS ceramics is significantly improved and the Curie temperature shifts to lower value with the amount of Y2O3 increased, making it a superior candidate for capacitor applications.

Analysis of Sampled Fiber Bragg Grating Based on the Photonic Crystal Theory

One of the most basic characteristics of photonic crystal is frequency band gap. When defects are introduced into the periodic photonic crystal, a number of defect modes appear in the stop band. In this paper, we exploit transfer matrix method based on photonic crystal theory, and assume the sampled fiber Bragg grating as one-dimensional dual photonic crystal with a large size defect. Characteristics of the sampled fiber Bragg grating are analyzed. Experimental results show that the sampled fiber Bragg grating has many reflective peaks. Its reflectivity, center wavelength, reflective peak intervals and band width all change with the grating parameters, including grating length, duty ratio of the material with high dielectric constant, and index modulation depth and period. Results agree with the conventional couple mode theory which can be used when analyzing other characteristics of the sampled fiber Bragg grating or applying it into practice.

Hybrid Slip Model for Near-Field Ground Motion Estimation Based on Uncertainty of Source Parameters

The hybrid slip model used to generate a finite fault model for near-field ground motion estimation and seismic hazard assessment was improved to express the uncertainty of the source form of a future earthquake.In this process, source parameters were treated as normal random variables, and the Fortran code of hybrid slip model was modified by adding a random number generator so that the code could generate many finite fault models with different dimensions and slip distributions for a given magnitude.Furth...

Analytical Bond-order Potential for hcp-Y

The lattice parameters, elastic constants, cohesive energy, structural energy differences, as well as the properties of point defects and planar defects of hexagonal closepacked yttrium （hcpY） have been studied with ab initio density functional theory for constructing an ex tensive database. Based on an analytical bondorder poial scheme, empirical manybody interatomic potential for hcpY has been developed. The model is fitted to some properties of Y, e.g., the lattice parameters, elastic constants, bulk modulus, cohesive energy, vacancy formation energy, and the structural energy differences. The present potential has ability to reproduce defect properties including the selfinterstitial atoms formation energies, vacancy formation energy, divacancy binding energy, as well as the bulk properties and the thermal dynamic properties.

Study on Negative Impact of Harmonic Components on Sensitive Electric Equipment

Distribution systems operators are often confronted with declined power quality, which can cause substantial economical losses. The problem analyzed in paper concerns thyristor controlled direct current motor used for ski-lift in ski resort as a source of disturbances with negative impact on sensitive electric equipment, which is then unable to operate correctly. To solve mentioned problems, series of measurements of voltage quality parameters were carried out according to the respective valid standards. Crucial power quality parameters necessary for parallel power active filter design were then analyzed. Power active filter compensates power factor and filters characteristic current harmonics. After power active filter was put into operation, power quality problems were eliminated. Payback period is estimated up to four years.