弹性管道三维小雷诺数流中的波动计算

本文利用文献[1]的杂交之法处理弹性管道三维粘性流体的波动问题,把流动区域分成远场与近场,远场的级数解形式由文献[2]给出,近场仍用有限元方法,但如今必须考虑三维情况。用数值方法求出与远场特征函数相应的特征方程的根,计算结果表明,除基本特征解为二维以外,其余一律衰减甚快。因此,多数情况下可以不计。

高温高压油井套管下放波动压力研究

波动压力是破坏井眼压力平衡系统导致井喷、井漏、井塌及其他复杂情况的重要原因,其预测及应用在钻井工程中占有重要地位。在固井作业下套管过程中,主要表现为激动压力,通过控制套管下放速度来控制激动压力,从而实现全过程平衡压力固井,不压漏低压层和保护薄弱地层。波动压力预测作为非常规套管柱设计的主要因素,在海洋高温高压钻井中显得尤为突出。尽管动态计算方法能较准确地计算井底波动压力,但是从安全角度来考虑,稳态法更适合实际工程计算。

哈拉军水电站引水发电系统水力过渡过程分析

哈拉军水电站引水发电系统较长,并设有调压井,通过过渡过程分析确定丢弃、增加负荷各工况下引水道主要节点水击压力变化规律及其最大、最小控制值、尾水管真空值;确定丢弃、增加负荷以上各种工况下引水道沿线的最大、最小内水压力分布规律;根据机组最高转速上升率和蜗壳末端最大动水压力;根据机组转速上升率和蜗壳末端最大动水压力标准,确定导叶事故关闭规律;确定各工况的机组转速变化规律及其最大上升率;调压井和机组小波动的稳定性,并最终确定调压井尺寸。研究成果对类似工程有十分重要的参考价值和指导意义。

矿井空压机房内变压器的选择

矿井空压机房内设10kV变配电设备为空气压缩机和空压机房周边单体建筑配电,结合母线电压、电动机电压波动计算以及变压器负荷率、过载能力的计算,合理确定变压器容量。

短流程工程电炉炼钢供电设计简述

电炉利用废钢作为原料,即减轻环境的压力,又减少吨钢能耗,电炉炼钢必将成为一种趋势。本文主要简单介绍短流程电炉炼钢的供电设计。

The anti-correlation method for removing harmonic distortion in vibroseis slip-sweep data

The slip-sweep technique is one of the high-efficiency, high-fidelity, and environmental vibroseis seismic prospecting techniques which consists of a vibrator group sweeping without waiting for the previous group＇s sweep to terminate. The cycle time can be reduced drastically and hence the production efficiency can be increased significantly but harmonic distortion of one sweep will leak into the record of the other sweep. In this paper, we propose an anti-correlation method for removing harmonic distortion in vibroseis data. This method is based on decomposition of the ground force signal into fundamental and harmonic components. Then the corresponding anti-correlation operator can be computed to estimate the energy of each harmonic after correlating the vibroseis data with the corresponding harmonic component. Finally, the vibroseis harmonic noise to be removed can be obtained by subtracting the extracted harmonic noise from the traces of the previous group＇s sweep. The advantage of the proposed method is that it can process both uncorrelated and correlated vibroseis seismic data. Moreover, the algorithm is simple, stable, and computationally fast. Especially, the significant contribution of this method is a considerable reduction in the harmonic without any alteration of the desired signals. The method was tested on both synthetic and field data sets to validate the good harmonic noise suppression results.

Calculation of Scale of Fluctuation and Variance Reduction Function

The scale of fluctuation is one of the vital parameters for the application of random field theory to the reliability analysis of geotechnical engineering. In the present study, the fluctuation function method and weighted curve fitting method were presented to make the calculation more simple and accurate. The vertical scales of fluctuation of typical layers of Tianjin Port were calculated based on a number of engineering geotechnical investigation data, which can be guidance to other projects in this area. Meanwhile, the influences of sample interval and type of soil index on the scale of fluctuation were analyzed, according to which, the principle of determining the scale of fluctuation when the sample interval changes was defined. It can be obtained that the scale of fluctuation is the basic attribute reflecting spatial variability of soil, therefore, the scales of fluctuation calculated according to different soil indexes should be basically the same. The non-correlation distance method was improved, and the principle of determining the variance reduction function was also discussed.

优化块选择策略的高性能可逆信息隐藏算法

块选择是改善基于像素值排序的可逆信息隐藏算法性能的关键策略,通过在波动性较小的块中优先嵌入数据,可提升相应算法的不可感知性。然而,现有计算波动值的方法准确性受限于分块大小、形状和所选用的预测器,所以设计一种可以在不同分块大小、不同分块形状、不同类型预测器下通用的计算方法就尤为重要。对于较大的或者形状不规则的分块,若用于参与扩展计算的像素空间位置相关性较弱,即使相应的块波动值较小,在实际嵌入过程中,也仍然可能导致无效平移。为了解决该问题,首先提出了一种改进的波动性定义,以同时考虑水平、竖直、双斜对角4个方向上下文像素的一致性,判断完局部邻域内相邻像素一致性后,再判断同一方向上两个邻域的整体像素一致性,提升了块选择的准确性;其次,考虑了最大值与次大值、最小值与次小值之间的切比雪夫距离,通过消减最大值或最小值像素的扩展来减少无效移位。实验结果表明,文中提出的方案可实现更好的不可感知性。

生产停滞对迈尔兹窑石灰质量的影响

分析了迈尔兹窑生产停滞期间的卸料节奏及其影响、石灰石的分解温度与分解时间的关系和石灰质量出现波动时间的计算,提出了减小石灰质量波动的措施。

A novel method to update dynamic pricing scheme for DiffServ

The discrete time model for a single link of Diffserv is considered in this paper. A novel algorithm is proposed to improve the robustness of the existing model. It allows the link price to fluctuate slightly around the equilibrium price. Simulations are performed to verify the effectiveness of the algorithm. This model solves the problem that the existing model can converge only under the strict condition.

导叶分段关闭对过渡过程影响的研究

该文讲述水轮机组甩负荷时,通过采取分段关闭导叶的措施,降低水击压力和机组转速上升,以改善机组的大波动过渡过程,达到把压力上升和转速上升控制在规范允许范围内的目的。

Mathematical simulation of steep waves at a focus point

Mathematical models simulating steep waves at a focus point are presented in this paper. Simulations of extreme waves in a model basin were used to determine the loads on floating structures induced by the waves. Based on a new wave theory, numerical test results show that the simulation procedure is effective and the induced motion of water particles in the front of waves is an important factor influencing impact loads on floating bodies.

Investigation of the Effect of Bulbuos Bow of Containership in Head Waves Using CFD

Reynold＇s averaged Navier-Stokes based CFD （computational fluid dynamics） technique WISDAM developed at The University of Tokyo is used to investigate and compare the hydrodynamic loads on container ship models SR108 and KCS in 120 degree regular oblique wave conditions. WISDAM has the capability of handling 6DOF （six degrees of freedom） in ship motions. Finite volume method with structured and overlapping grid system is employed. The flow variables are described in staggered manner, i.e., velocity components arc defined at the face center while pressure is at the cell center. Computational results agree favorably well with existing towing tank results especially for ship motions. Computational results also show that ship with bulbous bow experience higher hydrodynamic loads on bow section.

Calculation of slope-cover height under price fluctuation in open-pit mines

Leaving ditches between adjacent mining areas can effectively reduce re-stripping in the latter mining area and simultaneously lead to an increment in internal dumping costs in the former mining area. This paper establishes calculation models for these two marginal costs. The optimizing model for slope cover height can be determined by including marginal cost models in the objective function. The paper has two main contributions:(a) it fully considers redistribution of dumping space in the model;(b) it introduces price fluctuations and cash discounts in the model. We use the typical open-pit mine as an example to test and prove the model. We conclude that a completely covered slope is reasonable in Haerwusu open pit mine; in addition to an increasing price index, the slope cover height can be reduced; and that price changes are one of the most important influencing factors of slope cover height optimization in an open-pit mine.

Structural and Vibrational Study of 2-（Quinolin-8-yloxy）-Acetic Acid based on FT-IR-Raman Spectroscopy and DFT Calculations

We have prepared the 2-（quinolin-8-yloxy）-acetic acid and characterized it by infrared and Raman spectroscopies in the solid phase. The Density Functional Theory （DFT） method, together with the 6-31G^＊ and 6-311＋＋ G^＊＊ basis sets, show that three stable molecules, for the anhydrous and monohydrated compounds were theoretically determined in the gas phase, and that probably the two more stable conformations are present in the solid phase of the monohydrated compound. The harmonic vibrational wavenumbers for the optimized geometries were calculated at B3LYP/6-31G^＊and B3LYP/6-311＋＋G^＊＊ levels. For a complete assignment of all the observed bands in the vibrational spectra the DFT calculations were combined with Pulay＇s scaled quantum mechanical force field （SQMFF） methodology in order to fit the theoretical Wavenumber values to the experimental ones. The characteristics of the electronic delocalization of all structures of both forms were performed by using natural bond orbital （NBO）, while the corresponding topological properties of electronic charge density are analysed by employing Bader＇s atoms in molecules theory （AIM）.

Dynamic Interaction of Parallel Moving Ships in Close Proximity

Nowadays,there are many studies conducted in the field of marine hydrodynamics which focus on two vessels traveling and floating in sufficiently close proximity to experience significant interactions.The hydrodynamic behavior of parallel moving ships in waves is an interesting and important topic of late.A numerical investigation has been carried out for the prediction of wave exciting forces and motion responses of parallel moving ships in regular waves.The numerical solution was based on 3D distribution technique and using the linear wave theory to determine the exciting forces and ship＇s motion.The speed effects have been considered in the Green function for more realistic results.The numerical computations of wave exciting forces and motion responses were carried out for a Mariner and Series 60 for the purpose of discovering different Froude numbers and different separation distances in head sea conditions.Based on the numerical computations,it was revealed that the sway,roll and yaw have a significant effect due to hydrodynamic interaction.

Research on NC interpolation Algorithm based on STM32

This paper analyzes the principle of spline interpolation, pointed out the reasons for the feed rate fluctuations and proposed interpolation algorithm based on the secant iteration method NURBS curve. The algorithm of the speed the planning section uses cubic polynomial acceleration and deceleration control methods to ensure the acceleration of the process of continuous high-speed operation, so that the machine runs smoothly, avoiding the machine have a big impact; while parameter calculation part using the Secant iterative interpolation method to calculate parameter, reducing the speed fluctuation, the machine is further reduced tremor. Simulation results show that the algorithm can obtain a continuous velocity and acceleration curves, and can be controlled in real time interpolation velocity fluctuations in the ideal range, the machine achieve the smooth running ,and meet the high-speed, high quality processing requirements.

Calculating Binding Energy for Odd Isotopes of Beryllium （7 ≤ A ≤ 13）

In this article, we present exact solution of the Schr6dinger equation （for an N-identical body-force） for odd-A isotopes of Beryllium in the presence of Yukawa potential by Nikiforov-Uvarov （NU） method. The NU method can be used to solve second order differential equation. By this method, we find the wave equation and binding energy. Numerical results of binding energy are presented and show that these results are in good agreement with experimental values.

Lattice Boltzmann Simulation for the Spiral Wave Dynamics

We investigated the dynamics of the simple spiral waves of the Se/kov reaction-diffusion system with the Lattice Boltzmann method. The results of computer simulation lead to the conclusion that the trajectory of the spiral tip is a small circle, the wavelength and the period decay exponentially when the value of parameter b increases; and the relation between the wavelength and the period is λ ∝ T1/2, which is qualitatively the same as that obtained by Ou-Yang Qi from Belousov-Zhabotinsky reaction system.

Coupled Transport Phenomena in Corrugated Photocatalytic Reactors

Corrugated reactors are known for their use in applications requiring UV-exposure, whereby media flowing within the corrugated channel react with a photo-active catalyst impregnated on the surface （i.e. TiO2）. The performance in these systems is dependent on catalyst properties and reactivity for a given light source, in conjunc-tion with the coupled transport of reactants within the media and photons falling incident to the catalyst surface. Experimental and computational analyses of local mass transfer and radiation pattems for a broad range of corrugation angles, depths, and non-idealities introduced during manufacture （i.e. fold curvature） are thus integrated to the design and optimization of these systems. This work explores techniques for determining incident energy distribu-tions on the surface of corrugated reactor geometries with non-ideal cross-sectional profiles, and the local and overall mass transfer rates obtained using computational fluid dynamics and experimental analysis. By examining the reaction kinetics for the photo-degradation of 4-chlorophenol over a TiO2 catalyst, the effects of surface area, energy incidence with photon recapture, and local mass transfer on overall reactor performance are presented to highlight ootimization concerns for these tvoes of reactors.