A test of the Tate equation to predict bubble size at an orifice in the presence of frother     

Jose R. Hernandez-Aguilar  Ryan CunninghamJames A. Finch 《International Journal of Mineral Processing》2006

Air bubbles of uniform size (ca. 1 mm diameter) were generated at a submerged orifice (glass capillary) under controlled frequency (down to ca. 0.06 s^− 1) in aqueous solutions of frother (Dowfroth 250). The bubbles were sized with an imaging technique. One objective was to establish whether the Tate equation (static balance between buoyancy and capillary forces) could be used as a standard sizing calibration method. Another aim was to verify whether with decreasing surface tension (due to increasing frother concentration) the anticipated decrease in bubble size agreed with the equation prediction. An effect of frother was detected compatible with the role of surface tension but divided into two concentration regions, seemingly the result of a gradual change in bubble shape and wetting: > 6 ppm the bubble holds a spherical shape and the capillary appeared to be completely wetted while at ≤ 6 ppm a degree of non-wetting and bubble distortion (neck formation just prior to detachment) were apparent, supported by qualitative observations. In addition, at > 6 ppm the Tate value was only approached by decreasing the bubble frequency but not attained. Plausible causes for the failure to reach the predicted size are discussed.  相似文献   

The selection of appropriate spectrally bright pseudo-invariant ground targets for use in empirical line calibration of SPOT satellite imagery     

Barnaby Clark  Juha SuomalainenPetri Pellikka 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(4):429-445

The appropriate utilization of multi-temporal SPOT multispectral satellite imagery in quantitative remote sensing studies requires the removal of atmospheric effects. One widely used and potentially very accurate way of achieving absolute atmospheric correction is the calibration of at-satellite radiance data to field measures of the surface reflectance factor (ρ_s). There are a number of variations in this technique, which are known collectively as empirical line (EL) approaches. However, the successful application of an EL spectral calibration requires the presence and careful selection of appropriate pseudo-invariant ground targets within each scene area. Real surfaces, even those that are man-made and vegetation-free, display non-Lambertian reflectance behaviour to some extent. Because of the ±31° off-nadir incidence angle range of the SPOT sensors, this is a crucial consideration. In favourable circumstances, it may be possible to utilize a goniometer to collect multiangular ρ_s measurements, but for widespread lower cost application of EL approaches currently, the use of a handheld spectrometer to measure nadir only ρ_s is a more realistic proposition. In either case, the selection of targets that have more limited and stable multiangular reflectance behaviour is preferable. Details are given of the reflectance properties of a variety of spectrally bright potential calibration surface types, encompassing sands, gravel, asphalts, and managed and artificial grass turf surfaces, measured in the field using the Finnish Geodetic Institute Field Goniospectrometer (FIGIFIGO). Bright calibration site selection requirements for SPOT data are discussed and the physical mechanisms behind the varying reflectance characteristics of the surfaces are considered. The most desirable properties for useful calibration targets are identified. The results of this study will assist other workers in the identification of likely suitable EL calibration sites for medium and high resolution optical satellite data, and therefore help optimize efforts in the time consuming and costly process of measuring ρ_s in the field.  相似文献   

对中杆倾斜检校的新方法探讨     

郑平元  杨武年  余代俊  杨容浩 《四川测绘》2011,(4):178-180

现代测绘工作中全站仪正在被广泛使用,其配件棱镜对中杆以轻便实用等特点深受测绘工作者的喜爱,然而对中杆的倾斜与否将直接影响测量精度及测绘产品的质量。针对传统的对中杆检校方法繁琐不易操作的特点,本文提出了＂单方向十字交叉法＂和＂仪器脚架法＂这两种简单实用的检校新方法,并对它们的精度及应用领域进行了探讨。  相似文献   

机载POS系统中惯性测量单元精度检校方法     

曲直  卢秀山  左建章  马东洋 《测绘科学》2011,36(5):131-133,97

本文简要介绍了GPS/INS组合技术的优势和特点,分析了惯性测量单元(IMU)的工作原理及精度影响因素,系统阐述了机载POS系统中IMU的检校方法和精度评定方法,包括初始对准重复性检测、跟踪姿态角精度的标定和静态漂移检测等,并利用双轴数控转台,对3台不同类型的国产POS系统进行了数据采集、处理和对比分析,实验初步表明,...  相似文献   

THE CONSTRUCTION OF SIMULTANEOUS OPTIMAL EXPERIMENTAL DESIGNS FOR SEVERAL POLYNOMIALS IN THE CALIBRATION OF ANALYTICAL METHODS     

R.WOLTERS  G.KATEMAN 《地理学报(英文版)》1990,(2)

In this paper a criterion is described for the construction of experimental designs for the evaluation ofcalibration models in analytical chemistry.The proposed criterion seeks a compromise between theD-optimal designs for estimating the parameters of different polynomial models.A computer algorithmis presented for a sequential construction of experimental designs using the optimality criterion.Theperformance of the optimality criterion and the computer algorithm is elaborated for the problem ofdiscrimination between a first-to a third-degree polynomial for the calibration of analytical methods.Anexperimental design consisting of replicate measurements at five distinct levels equally spaced over thecalibration range proved a good solution.  相似文献   

GENERALIZED SIMULATED ANNEALING FOR CALIBRATION SAMPLE SELECTION FROM AN EXISTING SET AND ORTHOGONALIZATION OF UNDESIGNED EXPERIMENTS     

JOHN H.KALIVAS 《地理学报(英文版)》1991,(1)

ealibrared.The diseussion in this PaPer foeuses on near一infrared(NIR)sPeetroseoPy as the examPle instrument.However,the Proeedures Presented are aPPlieable tomost methods of instrumental analysis.Essentially,ealibration eonsists of assembling a seriesof samPles eontaining the analyte or analytes at  相似文献   

Calculation of Calibration Functions and Explosive Aftershock Magnitudes in the Near Field     

Li Xuezheng  Wang Haijun  Lei Jun 《中国地震研究》2003,17(4):305-314

The current calibration function used in calculating the magnitude of natural earthquakes within 5km is a constant; a fact that causes several serious difficulties for the calculation of the magnitude of small and shallow-focus earthquakes. According to the attenuation law of explosions and the propagation theory of elastic waves, the calibration function is calculated for near field quakes from 0kin to 5kin. Magnitudes of two aftershock sequences are calculated. The magnitudes of most explosion earthquakes are small, ranging mainly from magnitude -0.5 to 1.0. The M-t chart of the explosive aftershocks is completely different from that of strong earthquake aftershocks. It not only shows positive columnar lines indieatJng large magnitudes but also short negative columnar lines indicating small magnitudes.  相似文献   

Development of a geometric model for an all-reflective camera system     

《ISPRS Journal of Photogrammetry and Remote Sensing》2013

Currently in photogrammetry conventional camera optics, which are based on a combination of lenses, are solely used. These systems are also called refractive systems. The usage of refractive systems implies a general drawback for some applications. Due to the chromatic aberration of lenses, i.e. slightly different imaging functions for different spectral bands, a significant loss of image quality and geometric accuracy has to be accepted. This fact is important especially for applications that require imaging a wide spectral range. Conventional cameras are not able to satisfactorily capture the ultraviolet or near infrared spectral range in addition to the visible.These chromatic aberration problems can be completely be avoided in all-reflective optical systems, i.e. camera objectives which are completely based on mirrors. The paper will briefly describe the developed all-reflective optical systems designed for optical metrology purposes.A general disadvantage of the design of normal or wide angle all-reflective systems is the asymmetry of the mirror arrangement, which leads to large asymmetric geometric image distortions. These distortions cannot be modeled with standard methods of photogrammetry. Furthermore, the complete system is also more sensitive to local deviations from the ideal mirror surface. Therefore we developed a suitable geometric model, which is adapted to the special case. The model is based on the collinearity condition, extended by a specific additional parameter set optimized with regard to the characteristics of an all-reflective unobscured system. We will show various model variants based on the additional parameter sets of Brown, Ebner and Grün as well as Legendre polynomials, Chebyshev polynomials and Fourier series. The paper discusses the potential of these models to correct the distortion of an all-reflective unobscured optical system prototype based on four aspherical mirrors on the basis of test field self-calibration and describes different approaches to consider local deviations from the nominal aspherical mirror surface with the help of the finite elements method.  相似文献   

A calibrated,non-invasive method for measuring the internal interface height field at high resolution in the rotating,two-layer annulus     

P.D. Williams  P.L. Read  T.W.N. Haine 《地球物理与天体物理流体动力学》2013,107(6):453-471

We describe a remote sensing method for measuring the internal interface height field in a rotating, two-layer annulus laboratory experiment. The method is non-invasive, avoiding the possibility of an interaction between the flow and the measurement device. The height fields retrieved are accurate and highly resolved in both space and time. The technique is based on a flow visualization method developed by previous workers, and relies upon the optical rotation properties of the working liquids. The previous methods returned only qualitative interface maps, however. In the present study, a technique is developed for deriving quantitative maps by calibrating height against the colour fields registered by a camera which views the flow from above. We use a layer-wise torque balance analysis to determine the equilibrium interface height field analytically, in order to derive the calibration curves. With the current system, viewing an annulus of outer radius 125?mm and depth 250?mm from a distance of 2?m, the inferred height fields have horizontal, vertical and temporal resolutions of up to 0.2?mm, 1?mm and 0.04?s, respectively.  相似文献   

Absolute Calibration of the TOPEX/POSEIDON Altimeters using UK Tide Gauges,GPS, and Precise,Local Geoid-Differences     

Xiaojun Dong  Philip Woodworth  Philip Moore  Richard Bingley 《Marine Geodesy》2013,36(3):189-204

This article describes an "absolute" calibration of TOPEX/POSEIDON (T/P) altimeter bias using UK tide gauges equipped with Global Positioning System (GPS) receivers. The method is an extension of earlier work using the Newhaven tide gauge in the English Channel. However, the present analysis extends the research to a number of gauges around the UK and incorporates several improvements. The time-averaged TOPEX and POSEIDON biases are obtained with a precision of approximately 2 and 3 cm, respectively. The research complements work on bias determination by other groups in the T/P Science Working Team and can, in principle, be applied at other locations for which precise, local geoid-differences are available. The relatively sparse POSEIDON data set has been used as a test of our ability to perform an absolute calibration of upcoming Jason-1 altimetry as soon as possible after launch.  相似文献