HERMITE EXPANSIONS AND FRACTALMEASURES

Let mu be a locally uniformly alpha-dimensional measure on R-n and P-t(fd mu) be the Able Poisson means of Hermite expansions for f is an element of L-p(d mu), it is studied that the asymptotis properties of P-t(fd mu) as t --> 1_. Analogue of Wiener's theorem is obtained. Author also establishs the boundedness of the alpha-dimensional maximal conjugate Poisson integral operators from L-p(d mu) to the Lebesgne p-power integrable function spaces L-p(dx), and this derives directly the boundedness of Riesz transforms.

Spectral measurements of hypervelocity flow in an expansion tunnel

Atmospheric reentry vehicles and planetary probes fly through the atmosphere at hypervelocity speed. At such speed, there is a significant proportion of heat load to the vehicle surface due to radiative heating. Accurate prediction needs a good knowledge of the radiation spectrum properties. In this paper, a high-speed camera and spectrograph coupled to an intensified charge-coupled device have bee n impleme nted to inv estigate the rad i at io n flow over a semi-cylinder model. The experiments were carried out in the JF16 expansi on timnel with secondary shock velocity of 7.9 km·s^-1. Results show that the emissio n spectrum comprises several atomic lines and molecular band systems. We give detailed data of the radiation spectrum, shock shape, shock detached distance and radiation intensity varying with space and wavelength. This valuable experimental dataset will be helpful to validate computational fluid dynamics codes and radiation models, which equates to increased prediction accuracy of radiation heating. Also, some suggestions for spectral measurement in hypervelocity flow field were list in the end.

Numerical investigation of multi-beam laser heterodyne measurement with ultra-precision for linear expansion coefficient of metal based on oscillating mirror modulation

This paper proposes a novel method of multi-beam laser heterodyne measurement for metal linear expansion coefficient. Based on the Doppler effect and heterodyne technology, the information is loaded of length variation to the frequency difference of the multi-beam laser heterodyne signal by the frequency modulation of the oscillating mirror, this method can obtain many values of length variation caused by temperature variation after the multi-beam laser heterodyne signal demodulation simultaneously. Processing these values by weighted-average, it can obtain length variation accurately, and eventually obtain the value of linear expansion coefficient of metal by the calculation. This novel method is used to simulate measurement for linear expansion coefficient of metal rod under different temperatures by MATLAB, the obtained result shows that the relative measurement error of this method is just 0.4%.

Measurement and simulation of the two-phase velocity correlation in sudden-expansion gas-particle flows

In this paper the present authors measured the gas-particle two-phase velocity correlation in sudden expansion gas-particle flows with a phase Doppler particle anemometer （PDPA） and simulated the system behavior by using both a Reynolds-averaged Navier-Stokes （RANS） model and a large-eddy simulation （LES）. The results of the measurements yield the axial and radial time-averaged velocities as well as the fluctuation velocities of gas and three particle-size groups （30μm, 50μm, and 95μm） and the gasparticle velocity correlation for 30μm and 50μm particles. From the measurements, theoretical analysis, and simulation, it is found that the two-phase velocity correlation of sudden-expansion flows, like that of jet flows, is less than the gas and particle Reynolds stresses. What distinguishes the two-phase velocity correlations of sudden-expansion flow from those of jet and channel flows is the absence of a clear relationship between the two-phase velocity correlation and particle size in sudden-expansion flows. The measurements, theoretical analysis, and numerical simulation all lead to the above-stated conclusions. Quantitatively, the results of the LES are better than those of the RANS model.

Measurement Method of Compressibility and Thermal Expansion Coefficients for Density Standard Liquid at 2329 kg/m^3 based on Hydrostatic Suspension Principle

The accurate measurement on the compressibility and thermal expansion coefficients of density standard liquid at 2329kg/m3（DSL-2329） plays an important role in the quality control for silicon single crystal manufacturing. A new method is developed based on hydrostatic suspension principle in order to determine the two coefficients with high measurement accuracy. Two silicon single crystal samples with known density are immersed into a sealed vessel full of DSL-2329. The density of liquid is adjusted with varying liquid temperature and static pressure, so that the hydrostatic suspension of two silicon single crystal samples is achieved. The compression and thermal expansion coefficients are then calculated by using the data of temperature and static pressure at the suspension state. One silicon single crystal sample can be suspended at different state, as long as the liquid temperature and static pressure function linearly according to a certain mathematical relationship. A hydrostatic suspension experimental system is devised with the maximal temperature control error ±50 μK; Silicon single crystal samples can be suspended by adapting the pressure following the PID method. By using the method based on hydrostatic suspension principle, the two key coefficients can be measured at the same time, and measurement precision can be improved due to avoiding the influence of liquid surface tension. This method was further validated experimentally, where the mixture of 1, 2, 3-tribromopropane and 1,2-dibromoethane is used as DSL-2329. The compressibility and thermal expansion coefficients were measured, as 8.5′10–4 K–1 and 5.4′10–10 Pa–1, respectively.

The Approach of Compensation of Air Refractive Index in Thermal Expansion Coefficients Measurement Based on Laser Feedback Interferometry

We present the thermal expansion coefficient （TEC） measurement technology of compensating for the effect of variations in the refractive index based on a Nd： YA G laser feedback system, the beam frequency is shifted by a pair of aeousto-optic modulators and then the heterodyne phase measurement technique is used. The sample measured is placed in a muffle furnace with two coaxial holes opened on the opposite furnace walls. The measurement beams hit perpendicularly and coaxially on each surface of the sample. The reference beams hit on the reference mirror and the high-refiectivity mirror, respectively. By the heterodyne configuration and computing, the influences of the vibration, distortion of the sample supporter and the effect of variations in the refractive index are measured and largely minimized. For validation, the TECs of aluminum samples are determined in the temperature range of 29-748K, confirming not only the precision within 5 × 10-7 K-1 and the accuracy within 0.4% from 298K to 448K but also the high sensitivity non-contact measurement of the lower reflectivity surface induced by the sample oxidization from 448 K to 748 K.

An improved outer pipe method for expansive pressure measurement of static cracking agents

Static cracking agent(SCA)is actively investigated as an alternative to explosive blasting for rock breakage due to its immense expansion property.SCA can eliminate the negative effects of shock,noise and harmful gases encountered in explosive blasting processes.Accurate measurement and deep understanding of the expansive properties of SCAs are important in their industrial application.An improved outer pipe method(OPM),termed the upper end surface method(UESM),is proposed in this paper to overcome the shortcomings of the OPM in the expansive pressure measurement of SCAs.Numerical simulation is used to proof the concept and a mathematical model established to relate the internal pressure and the radial strains at different positions in the upper end surface method test equipment.The new equipment is calibrated using oil pressure and strain measurements.The calibrated equipment is then used to measure the expansion pressure of SCA at three different water contents to proof its potential.The differences in the measurements with OPM and UESM at three different moisture contents are less than 4%.The experimental results confirm the accuracy and applicability of the more user friendly and less expensive UESM in the measurement of the expansive pressures of SCAs.

Sparse Approximation of Data-Driven Polynomial Chaos Expansions: An Induced Sampling Approach

One of the open problems in the field of forward uncertainty quantification(UQ)is the ability to form accurate assessments of uncertainty having only incomplete information about the distribution of random inputs.Another challenge is to efficiently make use of limited training data for UQ predictions of complex engineering problems,particularly with high dimensional random parameters.We address these challenges by combining data-driven polynomial chaos expansions with a recently developed preconditioned sparse approximation approach for UQ problems.The first task in this two-step process is to employ the procedure developed in[1]to construct an"arbitrary"polynomial chaos expansion basis using a finite number of statistical moments of the random inputs.The second step is a novel procedure to effect sparse approximation via l1 minimization in order to quantify the forward uncertainty.To enhance the performance of the preconditioned l1 minimization problem,we sample from the so-called induced distribution,instead of using Monte Carlo(MC)sampling from the original,unknown probability measure.We demonstrate on test problems that induced sampling is a competitive and often better choice compared with sampling from asymptotically optimal measures(such as the equilibrium measure)when we have incomplete information about the distribution.We demonstrate the capacity of the proposed induced sampling algorithm via sparse representation with limited data on test functions,and on a Kirchoff plating bending problem with random Young’s modulus.

EXPERIMENTAL STUDIES ON SWIRLING AND RECIRCULATING TWO-PHASE FLOW FIELD IN A COLD MODEL OF DUAL-INLET SUDDEN-EXPANSION COMBUSTOR

The axial and tangential velocities of gas and particle phases and particle concentration for turbulent swirling and recirculating gas-particle (simulating gas-droplet) flows in a cold model of a dual-inlet sudden-expansion combustor with partially tangential central tubes, proposed by the present authors, were measured by using a 2-D LDV system and a laser optic fiber system combined with a sampling probe. The results show that there are both gas and particle strongly reverse flows and swirling flows in the head part of the combustor. The velocity slip between gas and particle phases is remarkable. The particle concentration is higher near the wall and lower near the axis. There are two peaks in the concentration profiles near the inlet tubes. The above-obtained flow characteristics are favorable to ignition, flame stabilization and combustion. The results can also be used to validate the numerical modeling.

Strain Capacities Limits of Wrought Magnesium Alloys: Tension vs. Expansion

Lightening structure is one of the goals of many fields of research. As a result, magnesium alloys are studied due to their low density. However, one drawback of these alloys is their low formability at room temperature due to their hexagonal closed-packed structure. In the present work, the forming capacity of an AZ31 Mg alloys has been studied using a mini deep-drawing device, image correlation techniques and tests (tension and expansion) at temperatures contained between 20°C and 200°C. To investigate formability limits of Mg alloys in expansion, major and minor strains data were generated using hemispherical punch tests and analyzed with 3D digital images correlation techniques. Thanks to images correlation, strains on the surface of the samples were observed by means of a double digitization of the sample in three dimensions before and after deformation by using stereoscopic vision and triangulation. Image correlations have also been used in 2D to measure strains on the surface of the tensile test samples. These tests gave interesting information on the evolution of various parameters such as hardening coefficient, strain rate sensitivity parameter, and Lankford coefficient, which may affect the behavior of the alloys. Finally, the forming limits in both configurations (tension and expansion) were compared and discussed.

Gravity vs. Dark Energy, about the Expansion of the Universe

Dark energy is argued by the accelerating expansion of the Universe but has not been directly measured. In this article, some uncertainties are pointed out, first one being the determination of the Hubble constant. And the main parameters (magnitude, distance, redshift, velocity) are checked. Distinguishing the instantaneous velocity from the average velocity, it is then concluded from the same data that the expansion would not be accelerating, and that the Gravity would slightly slow down the motion of explosion. Moreover, at the end of the paper, it is proposed a neo-Newtonian approach to get the computed values in a closer agreement with the observed values;this Neo-Newtonian Mechanics is in coherence with the Quantum Mechanics.

DEWATERING MEASURE APPLIED TO SOLVE LANDSLIDE PROBLEM IN EXPANSIVE SOIL AREA

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作物茎秆膨胀收缩监测柔性可穿戴传感器研制与试验

作物茎秆膨胀和收缩变化与其水分状态密切相关,实时监测茎秆的膨胀和收缩变化能够及时掌握作物水分状态,对指导灌溉、提高农业水资源利用率具有重要意义。目前,对于作物茎秆膨胀和收缩变化的监测主要采用基于线性微位移测量原理的传感器,通过测量茎秆的膨胀和收缩引起的位移变化来反映水分状态,存在体积大、价格高、安装不便等问题。为此,该研究提出了一种基于压阻效应的柔性可穿戴传感器,采用柔性压力电极作为传感元件,贴附在作物茎秆表面,通过监测茎秆膨胀和收缩引起的压力变化来反映作物的水分状态,压力检测电路和数据采集电路将作物茎秆的压力信号转换成电信号进行输出和存储。首先在实验室环境下对传感器性能进行测试和标定,然后在温室环境下将传感器安装在番茄茎秆上观测番茄茎秆的压力变化,并与线性微位移传感器观测结果进行比较,最后在充分灌溉和水分亏缺2种条件下观测番茄茎秆的膨胀和收缩变化。结果表明,柔性压力传感器稳定性测试的平均相对变化率为0.109%;弯折前后引起的输出变化非常小,可以忽略不计;标定结果的决定系数大于0.99,最合适的工作压力范围为2~100 kPa;实验室环境下,柔性压力传感器与线性微位移传感器输出值之间的决定系数为0.9551;温室环境下,充分灌溉组中柔性压力传感器与线性微位移传感器输出值变化趋势一致,两者之间的决定系数为0.7672,亏缺灌溉组中两类传感器输出值均因水分亏缺而呈现下降趋势,输出值之间的决定系数为0.8519。本文所设计的柔性可穿戴压力传感器不仅能够实时监测番茄茎秆的膨胀和收缩变化,还可以对番茄亏水胁迫进行诊断,为实现高效节水灌溉提供重要的技术支撑。

野马优化算法的PID控制器在炼焦煤膨胀压力测定装置中的应用

探讨了野马优化算法在炼焦煤膨胀压力测定装置的PID控制器参数优化中的应用。炼焦煤膨胀压力的精确测量对于控制焦炭质量和优化炼焦工艺至关重要。首先对膨胀压力测定装置的控制系统进行搭建,包括其结构、工作原理以及集成的传感器和可编程逻辑控制器(PLC)。随后,介绍了WHO算法优化PID参数的实施流程,包括野马群体的初始化、性能评估、基于WHO规则的PID参数更新及迭代优化过程。实验结果表明,WHO优化的PID控制器在温度控制精度、系统响应速度和稳定性方面均优于传统方法。特别是在处理非线性和复杂的热解过程中,优化后的控制器能够更有效地应对温度变化,确保膨胀压力的准确测量。这一改进显著提高了炼焦煤膨胀压力测定装置的性能,为精确控制焦炭质量和优化炼焦工艺提供了重要的技术支持。

基于柱面波展开的准远场快速测量方法研究

为解决常规暗室环境不满足大口径天线的测量需求、测试系统复杂以及测试效率低等问题,文中对天线测量中的高效测量方法进行了研究,重点研究了准远场快速测量方法,提出了一种基于柱面波展开理论的准远场变换算法。该算法适宜在准远场距离下对一维电尺寸大而另一维电尺寸小的天线进行测量,提高了此类天线的测试效率和现有暗室的测试能力。为了验证所提出的方法,利用电磁仿真软件设计了三个均匀分布的线性阵列。仿真和实物测试结果验证了所提出方法的正确性。

膨胀土地层深基坑变形分析及控制

在膨胀土地层的深基坑施工,采集围护结构变形情况的监测数据,能分析出变化量最大部位在时间和空间上的分布,再结合施工步序,提前采取相应措施,或者优化开挖工序,指导施工。本文以某车站深基坑监测为例,对膨胀土地层深基坑的围护结构变形情况进行分析,阐述监测数据的变形规律,总结施工过程中各项变形控制措施的有效性。可以有效地避免膨胀土地层对围护桩变形产生的不利影响,保证了基坑施工安全。通过总结膨胀土地层对基坑开挖各个时期的影响情况,提出合理化的控制措施和实用建议,为相关地区类似项目开展提供参考。

驷马山分洪道高切岭段右岸渠坡稳定性勘察评估与阻滑措施分析

驷马山分洪道高切岭段渠道因其特殊地形地貌条件,且渠坡揭露地层具膨胀性,历年来屡次发生滑坡现象。本文通过分析其滑坡的特点和成因,并在高切岭段右岸渠坡选取典型断面进行勘测评估,探索一种膨胀土边坡勘察的方法,分析膨胀性土边坡滑动带或潜在滑动带的发育深度和力学特性,在此基础上根据边坡特点进行稳定性分析,为膨胀土边坡的阻滑防治提供参考。

高速公路扩容项目中激光雷达测量技术的应用

G4215蓉遵高速公路(四川境段)扩容工程项目利用机载激光雷达对复杂地表进行快速、精确地探测,既能保证高速公路正常运行,又能保证快速获得高精度测图。论文详细探讨了机载激光雷达技术原理与应用情况,并围绕该项目区具体论述了机载激光雷达技术在工程测量中的应用。

干湿循环条件下膨胀土边坡失稳分析

为有效探究干湿条件下膨胀土边坡失稳机理,提高边坡滑坡治理效果,文中依托贵安新区市政道路边坡滑坡处置实例,分析干湿循环作用对膨胀土强度的影响,深入研究膨胀土边坡三种代表性失稳破坏形式及形成机理,并提出针对性处置措施。

新景煤矿15226综放工作面陷落柱超深孔扩裂爆破研究

陷落柱是煤矿开采中经常遇到的地质构造,对安全回采效率产生不利的影响。新景煤矿15226工作面揭露了X3、X4、X5和X6陷落柱,为保证工作面安全回采,提高开采效率,采用超深孔扩裂爆破的方法对陷落柱进行处理。结合地质资料和物探资料确定4个陷落柱的位置及形态,并确定了超深孔的布置方式及参数,分析了超深钻孔的施工工艺并探讨了超深孔爆破时的安全措施。实践表明,15226工作面顺利通过X5和X6陷落柱,且与未做深孔爆破处理时相比,截齿的消耗速度下降了74.21%,工作面的推进速度提升了16.1%,说明超深孔爆破技术保障了工作面的安全高效开采。