半参数测量模型在GPS高程拟合中的应用

利用罚最小二乘原理构造加权惩罚平方和,将半参数回归模型与最小二乘配置结合起来,来处理GPS高程问题,导出了配置型模型中正规化矩阵正定时参数平差的计算方法,用直接法得到了参数和信号的估计量,给出了相应的公式。其次,通过选取合适的平滑因子,能使残差的分布更接近其真实分布,并用一个实例说明了此方法的有效性。

基于混合高斯过程的多模型热力参数测量软仪表

为了解决工业过程中参数失效和优化运行中参数计算的问题,提出了一种新型软仪表,它是基于混合高斯模型,利用EM算法实现对混合模型中的参数估计。混合模型的使用既有利于降低单一高斯模型的计算负担,又能有效反映工业过程中的工况变化,判断出与特定工况相关程度最大的过程知识,利用它们建立与特定工况对应的局部模型,并将它们合并组成具有多模型结构的全局模型。作为示例,建立了测量火电厂烟气含氧量的软仪表。仿真结果表明,文中提出的方法能有效地实现工业过程参数的软测量,具有较大的实用价值。

半参数测量误差模型中参数的随机加权估计

给出了半参数测量误差模型中参数的随机加权最小二乘估计.讨论了用随机加权方法逼近最小二乘估计的分布,证明这种逼近是以概率1渐近有效的,并用模拟例子验证了提出方法的有效性.

基于HP-54504A的物理模型参数测量系统的研制与开发

介绍了一种物理模型参数测量系统。系统由HP 5 4 5 0 4A示波器、微机、IEEE 4 88接口卡、同步触发器、超声发射源和放大器组成。系统有外同步和内同步两种工作方式。使用OMT方法设计该系统 ,面对对象设计软件。系统在PC机Windows98环境下运行。介绍了系统的功能及进行物理模型参数测量的开发实例。该系统的开发为HP 5 4 5 0 4A用户提供了方便。

连续小推力航天器自主导航及在轨参数标定

以连续小推力航天器为背景,提出了综合考虑星载加速度计和推力器在轨标定的自主导航方案。首先以精确姿态测量和引力梯度模型为标定参考信息源,建立了包含加速度计参数、推力器参数以及光压系数的完整参数测量模型;然后基于天文导航方法建立了自主导航系统状态模型和观测模型;表明各状态和参数的能观性后,采用了具备良好计算效率和鲁棒性的双重无迹卡尔曼滤波方法进行状态和参数联合估计。分析与数值仿真表明,该方法通过结合参数在轨标定直接提高了导航模型精度,在工程应用中具备可行性和有效性。

Effect of gas saturation on P-wave velocity in tight sandstone

By measuring the variation of the P-and S-wave velocities of tight sandstone samples under water saturation,it was confirmed that with the decrease in water saturation,the P-wave velocity first decreased and then increased.The variation in velocity was influenced by the sandstone’s porosity.The commonly used Gassmann equation based on fluid substitution theory was studied.Comparing the calculated results with the measured data,it was found that the Gassmann equation agreed well with the measured data at high water saturation,but it could not explain the bending phenomenon of P-wave velocity at low saturation.This indicated that these equations could not accurately describe the relationship between fluid content and rock acoustic velocity.The reasons for this phenomenon were discussed through Taylor’s expansion.The coefficients of the fitting formula were calculated and verified by fitting the measured acoustic velocity changes of the cores.The relationship between P-wave velocity and saturation was discussed,which provides experimental support for calculating saturation using seismic and acoustic logging data.

半参数可加测量误差模型的白噪声检验

当模型误差不是白噪声时,通常的估计方法无效,特别是当回归因子包含后延变量时,估计不相合.因此,文章研究了半参数可加测量误差模型的白噪声检验.提出了一个白噪声检验统计量,并在模型误差是白噪声的零假设下证明了所提检验统计量服从渐近正态分布.随机模拟表明所提出的检验统计量具有良好的检验功效和水平.

Estimation of Geodetic Parameters with VLBI Data of Last 5 Years

The meaning to research the potential of VLBI for geodetic applications is summarized. And the observation models and their related parameters of geodetic interest are investigated. Then, the principle and method of using the random model in VLBI data processing are investigated. With the world wide VLBI data from 2000-2004, the conditions to compute the parameters of geodetic interest are introduced, and so are the computing methods and processes. And the computed resuits of the parameters of geodetic interest are analyzed.

Correlates of subjectively and objectively measured physical activity in young adolescents

Background： Many studies examining individual-level correlates in youth utilize self-report rather than objective measures of physical activity （PA）. This utilization of self-report may result in associations that are not present when examining objectively measured PA. The present study investigates the relationship between hypothesized correlates of PA with objectively and subjectively measured PA. Methods： Participating children （n 232, 101 males, mean age - 12.3 years） provided a minimum of four monitored days of PA （via accelerometer） and completed a survey assessing moderate-to-vigorous physical activity （MVPA）, sport competence, appearance, enjoyment, and self-efficacy. Height and weight were measured and body mass index （BMI） was calculated. Results： Hierarchical regression models controlling for sex, race, and BMI Z-score showed that only sex and BMI Z-score were significant correlates of objective MVPA while only sex was a significant correlate of objective total PA. However, in a separate model examining the relationship with subjective MVPA, enjoyment of PA and self-efficacy for PA were the only significant correlates of self-reported PA. Conclusion： Measuring MVPA via self-report versus accelerometry produces considerably different results in a sample of young adolescents. Future studies should use caution when selecting outcome measures if the intent is to identify modifiable correlates of MVPA in youth.

Investigation of Key Parameters for 3-D Dredging Plume Model Validation

Dredging plume dispersion studies, use dredging plume models to predict the fate of sediment plumes resulting from dredging activities and dredge spoil disposal. The model results are applied as input to environmental impact assessment of the proposed dredging, particularly those associated with suspended sediments and sedimentation. Model validation and performance are still not resolved because of the difficulty of site measurements and the understanding of the parameters used in the model. This paper presents a 3-D dredging plume model based on the MIKE3 software package to investigate parameters which affect the model performances. As a result of lack of site data for the public domain uses, the model scenarios are designed artificially for sensitive runs to identify the key parameters affecting plume behaviours. The factors include dredging spill rates using different dredging methods, equipment and sediment settling velocities. The influence of wave and wind effects combined with tidal forces on the sediment re-suspended rates and the advection/dispersion scales are also assessed.

Enhancing pose accuracy of space robot by improved differential evolution

Due to the intense vibration durirLg launching and rigorous orbital temperature environment, the kinematic parameters of space robot may be largely deviated from their nominal parameters. The disparity will cause the real pose （including position and orientation） of the end effector not to match the desired one, and further hinder the space robot from performing the scheduled mission. To improve pose accuracy of space robot, a new self-calibration method using the distance measurement provided by a laser-ranger fixed on the end-effector is proposed. A distance-measurement model of the space robot is built according to the distance from the starting point of the laser beam to the intersection point at the declining plane. Based on the model, the cost function about the pose error is derived. The kinematic calibration is transferred to a non-linear system optimization problem, which is solved by the improved differential evolution （DE） algoritlun. A six-degree of freedom （6-DOF） robot is used as a practical simulation example, and the simulation results show： 1） A significant improvement of pose accuracy of space robot can be obtained by distance measurement only; 2） Search efficiency is increased by improved DE; 3） More calibration configurations may make calibration results better.

Ventilation and climate simulation with the Multiflux code

Multiflux, a new thermal, hydrologic, and airflow model and software was being employed to solve the flow of heat, moisture, and air in and around an underground opening. The airway domain was solved with an integrated-parameter Computational Fluid Dynamic （CFD） module, which is an embedded part of the Multiflux code. The CFD model includes convection, conduction, and radiation for heat, as well as convection and diffusion for moist-ure transport in an air-filled opening. The surrounding rockmass model may be from any analytical solution, or from a complex thermal-hydrologic numerical model such as NUFT or TOUGH2. The rockmass model is interfaced to Multiflux using a novel technique called Numerical Transport Code Functionalization （NTCF）. The purpose was to briefly describe the Multiflux model and show four example applications. The first example reports the results of Multiflux simulations for a mine drift, comparing calculations with CLIMSIM, a well known mine climate software, and with measured data. The second and third examples involve development ends in two coal mines. Another development-end ventilation model in Multiflux is also shown as the 4th example compared with field measurements from the Lucky Friday Mine in Idaho, USA for comparison.The results of the study show very good agreement between the Multiflux model and the available measured field results.

Dark energy and fate of the Universe

We explore the ultimate fate of the Universe by using a divergence-free parametrization for dark energy w（z）=w0＋wa, [In（2 ＋ z） / （1 ＋ z） - In 2] . Unlike the Chevallier-Polarski-Linder parametrization, this parametrization has well behaved, bounded behavior for both high redshifts and negative redshifts, and thus can genuinely cover many theoretical dark energy models. Alter constraining the parameter space of this parametrization by using the current cosmological observations, we find that, at the 95.4% confidence level, our Universe can still exist at least 16.7 Gyr before it ends in a big rip. Moreover, for the phantom energy dominated Universe, we find that a gravitationally bound system will be destroyed at a time t = P√2｜ 1 ＋ 3w（ 1）] / [6π] 1 ＋ w（-1）｜], where P is the period of a circular orbit around this system, before the big rip.

From strangelets to strange stars:a unified description

The conventionally separated treatments for strangelets and strange stars are now unified with a more comprehensive theoretical description for objects ranging from strangelets to strange stars. After constraining the model parameter according to the Witten–Bodmer hypothesis and observational mass–radius probability distribution of pulsars, we investigate the properties of this kind of objects. It is found that the energy per baryon decreases monotonically with increasing baryon number and reaches its minimum at the maximum baryon number, corresponding to the most massive strange star. Due to the quark depletion,an electric potential well is formed on the surface of the quarkpart. For a rotational bare strange star, a magnetic field with the typical strength in pulsars is generated.

Effects of a Family Non-universal Z' Boson in B_d → μ^+μ^-and B^-→ π^-μ^+μ^-,ρ^-μ^+μ^-Decays

Motivated by the recently updated experimental measurement on Bd→μ^＋μ^- and B^-→π^-μ＋μ^- decays by CDF and Belle collaborations, we revisit these decays, as well as B^-→ρ^-μ^＋μ^- decay, within the Standard Model, and evaluate the effects of a family non-universal Z＇ boson. Under the constraint from β（B- → π^-μ＋μ^-）, we find the ranges of the Z＇ couplings SLRμμ 〈 -5.2 × 10^-2 or Dμμ^LR 〈 -8.1 × 10^-2 are excluded. Within the allowed Z＇ parameters spaces, comparing with the SM predictions, we find that B（Bd→μ^＋μ^-）, B（B^-→π^-μ＋μ^-）, and B（B^-→ρ^-μ＋μ^-） could be enhanced by a factor about 226%, 245%, and 254%, respectively, by Z＇ contributions. However, they are hardly to be reduced. Furthermore, the zero crossing in the normalized forward-backward asymmetry spectrum of B^-→ρ^-μ＋μ^- decay at low dimuon mass always exists.