Verification of Articulated Arm Coordinate Measuring Machines Accuracy Using LaserTracer System as Standard of Length

This article describes a novel approach to verification of articulated arm coordinate measuring machines (AA CMMs) based on ISO 10360-2 standard. The approach utilizes the LaserTracer (LT) system as standard of length and automation of calibration procedure using an industrial robot. In this method, the robot is programmed to repeatedly move the AA CMM. The retroreflector is integrated with the stylus of AA CMM. Location of the retroreflector is constantly tracked by LaserTracer and, in select positions, the measurements of distance are performed by both the AA CMM and LT system. The verification of AA CMM accuracy is carried out through the comparison of the two measurement values. The developed procedure is recommended mainly for checking AA CMMs with large measuring volume, where the application of common artefacts is usually insufficient, or time-consuming, due to the fact that measurements have to be performed for several subspaces in the AA CMM measuring volume.     

Calculating the optimal time when albedo approximates its daily average: an example using soil surfaces with various roughnesses at different latitudes

This paper describes how the blue-sky albedo of soil varies during the whole year from midday to sunset under clear-sky conditions. A hemispherical-directional reflectance model was used to calculate albedo variations associated with smooth, moderate and rough soil surfaces, located between the latitude angles of 75° in the Northern and Southern Hemispheres. We calculate the time when the albedo, acquired by an instantaneous observation, best represents its daily averaged value. This optimal time range is assessed in the context of remote-sensing satellite technology.     

SAP实施项目案例研究

引言 SAP开发并不断改进的管理系统能够为各种公司的管理提供支持，因而在全世界范围内获得了广泛应用。这一系统在不同时期有不同的名称，如R／3（20世纪90年代中期）、mySAP．com（2000年前后）以及mySAP ERP，在本文中统称为SAP系统。     

GEANT4 simulation of slow positron beam implantation profiles

The paper presents the positron implantation profiles, which are important for proper interpretation of data produced in slow-positron depth defect spectroscopy (VEPAS). In the paper, we compared the profiles reported in other publications and those obtained using the GEANT4 codes, which are used for the simulation of interaction of energetic particles with matter. The comparison shows that the GEANT4 codes produce profiles which match fairly well with those generated by other codes, which take into account more accurately processes at low energies when positrons interact with core electrons, valence electrons, plasmons etc. The profiles in different materials simulated for different implant energies were parameterized using two analytical formulas: the Makhovian profile and the profile proposed by Ghosh et al. [V.J. Ghosh, D.O. Welch, K.G. Lynn, in: E. Ottewite, A.H. WeissSlow (Eds.), Positron Beam Techniques for Solids and Surfaces, Jackson Hole, Wyoming, AIP Conference Proceedings, Vol. 303, New York, 1994, p. 37]. The adjustable parameters obtained are presented in Table 1 and Table 2. The total backscattering probability obtained from the GEANT4 simulations is in agreement with experimental data reported.     

Cobalt cationic sites in ferrierites: QM/MM modeling

Cobalt(II) sites in ferrierites are already well-known from their catalytic activity, their speciation and properties, however, the knowledge are far from completeness. The following paper presents the first in literature combined QM/MM study to elucidate the structure of these sites. With this end force-field parameters describing Co interactions with ionic shells in zeolite have been tested and the cell size for various Al distributions and Co positioning has been determined. Oxide-type Buckingham parameters are shown to perform better than the carbonate ones. Moreover, Co(II) ions stability in α and β sites with various Al distribution indicates at T1T1 Al substitution in β-site as that the preferred Co(II) siting. DFT results show that the quartet spin state of Co(II) is more stable than the doublet one.     

The influence of different additives on the solid-state reaction of magnesium hydride (MgH2) with Si

The possibility of increasing the solid-state reaction rate of MgH₂ with Si by modifying the mixture preparation method and adding chemical compounds or elements, such as niobium pentafluoride (NbF₅), nano-titanium (IV) oxide (TiO₂), nano-chromium (III) oxide Cr₂O₃, yttrium, and nano- and microsized nickel, was investigated. The results show that changing the milling parameters of the MgH₂ and Si mixture in a planetary ball mill greatly affects the rate of direct reaction between them and allows the reaction to take place at temperatures as low as 200 °C with an equilibrium pressure over 1 bar. Moreover, all additives significantly enhanced the reaction speed. The reaction pathway was found to be different for decomposition in a hydrogen vacuum and pressures of several bars. Reactions of the powders investigated did not occur at temperatures below 150 °C.     

Study on the microstructure of thin-layer facade plasters of thermal insulating system during artificial weathering

Investigations involving the influence of simulate weathering on the microstructure of thin-layer plasters laid on foamed polystyrene are reported. In order to examine internal changes, two kinds of properties were examined in time per 100 cycles during 400 cycles. One of the properties is an open porosity connected with pore structure tested by the mercury intrusion method (MIP), and total porosity examined by helium intrusion technique (HIP). The other property is mineral composition analyzed on X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results have shown that changes of porosity, pore structure and chemical microstructure of plasters occured after successive weathering. In tested plasters, greater changes were noticed above the gaps of thermal insulation boards than beyond them. Porosimetry tests resulted in greater variations of open porosity over the gaps. Similarly, higher amounts of calcium carbonate were found in plasters and background mortars in places over the gaps of polystyrene boards.     

Grain size correlation with the geometry of fracture surface profiles in polycrystalline iron by a continuous wavelet transformation method

A quantitative relationship is examined in this paper between the mean diameter of grains in iron of technical purity and the distance between the local maxima on the profiles Z(x) of the fracture surfaces obtained as results of Charpy impact tests at liquid nitrogen temperature.To this end, the profiles were digitized and analyzed with a Continuous Wavelet Transformation (CWT). Such a transformation assigns to each profile the scale and shift parameters C (a, b), which are further used to measure the distance between the local maxima. The distance between local maxima has been determined for each profile and its average value calculated.The grain size of the iron was controlled by cold deformation and recrystallization for different times and temperatures. The cryo-impact tests were performed on samples with two types of notch: (a) typical of a Charpy Test and (b) obtained as fatigue pre-crack tips.The results of the investigation reveal a strongly non-linear relationship between the average size of grains and the distance between the local maxima on the fracture surface profiles. This finding is discussed in terms of crack interactions with the grain boundaries.     

ICP/MS and ICP/AES elemental analysis (38 elements) of edible wild mushrooms growing in Poland

Thirty-eight elements, including toxic cadmium, lead, mercury, silver and thallium, were determined in 18 species of wild edible mushrooms collected from several sites in Pomorskie Voivodeship in northern Poland in 1994. Elements were determined by double focused high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES), after wet digestion of the dried samples with concentrated nitric acid in closed PTFE vessels using a microwave oven. K, P and Mg were present at levels of mg/g dry matter; Na, Zn, Ca, Fe, Cu, Mn, Rb, Ag, Cd, Hg, Pb, Cs, Sr, Al and Si were present at µg/g levels, while Tl, In, Bi, Th, U, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, La, Lu and Ba were present at ng/g levels.