Data Acquisition and Analysis

The various approaches employed for depth profiling through XPS are the angular studies, inelastic losses, and sputtering. 

The intensity of a given photoelectron line is proportional to the X-ray flux, cross-section for exciting the particular level, density of the particular atom in the lattice x, the escape depth for electrons of the resulting kinetic energy, asymmetry factor in the angular distribution of the photoionization event, transmission of the analyzer, which includes the acceptance angle and area, and the efficiency of the electron detector. In addition, there are several secondary factors, some of which depend on the matrix. The intensity of line is given by 

It is difficult to apply calculated 7 directly to XPS data. Other instrumental parameters need to be included about which enough information must be available to make an analysis from first principles. 

Most analyses use empirical calibration constants, ASF called atomic sensitivity factors) derived from standards 

The ASF for H, He is, however, very small (undetectable in conventional XPS). For applying ASF method, one should choose XPS peak with largest ASF to 

In measured neutron reflechvity curves, the error points in the experimentally measured data represent the stahstical errors in the measurements (standard 

The uncorrected specular data are shown as the square data points, while the triangles and circles show the background reflectivity 

A more detailed description of the analysis of neutron reflectivity data is provided with the aid of hypothetical examples. The reflection of neutrons from a multilaminar interface can be calculated in an analogous fashion to the optical matrix method for electromagnetic radiation [34, 35], provided the SLD, roughness, and thickness of each layer are known. For neutrons, the refractive index of a given phase may be calculated from the knowledge of the SLD, p, using Eq. (3.15). The dependence of the S LD on the composition of a given phase is described by the formula 

When the SLD profile of an interface is known, a matrix method or a recursion method can easily be used to calculate reflectivity curves. However, for pedagogical purposes the relationship between the reflectivity and the structure of the interface is better revealed by the analytical expressions derived with the help of the kinematic approximation. The kinematic approximation has been shown to describe the reflection of neutrons from stratified media very well when the reflectivity is significantly less than unity. When a film of SLD pi and thickness t, is sandwiched between two phases of identical SLD p, the expression for the reflectivity derived from a kinematic approach is [36] 

The above discussion reveals how NR can be used to provide direct information concerning both the thickness and the composition via the SLD of the various layers in the interface. This constitutes an advantage over ellipsometry or surface plasmon resonance methods where the value of the refractive index (composition) of the film is usually assumed in order to determine its thickness. However, to use the kinematic approach to directly determine these quantities, the reflectivity has to be measured in a sufficiently large range of so that at least one-half of the longest period interference fringe, corresponding to the thirmest layer in the interface, is observed on the reflectivity curve. The spatial resolution for a film of thickness ris defined as t= 7r/Qz,max, where is the maximum momentum 

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In another type of measurement, the parallel between mechanical and electrical networks can be exploited by using variable capacitors and resistors to balance the impedance of the transducer circuit. These electrical measurements readily lend themselves to computer interfacing for data acquisition and analysis. 

Mass and energy balances are used to evaluate blast furnace performance. Many companies now use sophisticated computeri2ed data acquisition and analysis systems to automatically gather the required data for daily calculation of the mass and heat balances. Typical mass and heat balances are shown in Figure 4 and Table 5, respectively. 

While providing many advantages, simplified data acquisition and analysis also can be a liability. If the database is improperly configured, the automated capabilities of these analyzers will yield faulty diagnostics that can allow catastrophic failure of critical plant machinery. 

There are several limitations of the computer-based systems and some system characteristics, particularly simplified data acquisition and analysis, provide both... 

Beware that this type of coupling often may go undetected in a normal vibration analysis. Since the ghost frequencies are relatively high compared to the expected real frequencies, they are often outside the monitored frequency range used for data acquisition and analysis. 

Repeated twisting of the spindle s tube or the solid shaft used in jackshafts results in a reduction in the flexible drive s stiffness. When this occurs, the drive loses some of its ability to absorb torsional transients. As a result, damage may result to the driven unit. Unfortunately, the limits of single-channel, frequency-domain data acquisition prevents accurate measurement of this failure mode. Most of the abnormal vibration that results from fatigue occurs in the relatively brief time interval associated with startup, when radical speed changes occur, or during shutdown of the machine-train. As a result, this type of data acquisition and analysis cannot adequately capture these... 

The spectrometer was a Physical Electronics Model 548 modified for emplacement in a glovebox so that actinide samples could be examined. Spectra were taken using AIK radiation (1486.6 eV). The overall energy resolution of tne spectrometer was 1.2 eV using an analyzer pass energy of 25 eV. The spectrometer control was interfaced to a Nicolet 1180 minicomputer providing automatic data acquisition and analysis capability. 

PECD in Camphor Convergence of the Partial Wave Expansion 1. Data Acquisition and Analysis Molecular Conformation and Substitution Effects 1. Data Acquisition and Treatment... 

The authors wish to acknowledge the help of W. E. Coiner and J. L. Sills, Jr. who contributed to data acquisition and analysis. Also, we wish to thank Professor A. E. Hamielec and Dr. A. Husain for providing us with computational software and for their helpful discussions throughout the course of this work. 

Electrochemical Measurements. The electrochemical instrumentation included (a) a PAR model 263A potentiostat, (b) a PAR PowerCV software for data acquisition and analysis, and (c) a Dell Pentium IV computer. 

Implementation of MRI to quantify holdup and wetting in packings of porous packing elements (e.g., catalyst support pellets) must be performed with care. Difficulties in data acquisition and analysis arise because the signal we wish to... 

Apparatus. Since all the polymer modification reactions presented in this paper involved gas consumption, an automated gas consumption measuring system was designed, fabricated and used to keep constant pressure and record continuously the consumption of gas in a batch type laboratory scale reactor. Process control, data acquisition, and analysis was carried out using a personal computer (IBM) and an interface device (Lab-master, Tecmar Inc.). 

A computer-controlled rheology laboratory has been constructed to study and optimize fluids used in hydraulic fracturing applications. Instruments consist of both pressurized capillary viscometers and concentric cylinder rotational viscometers. Computer control, data acquisition and analysis are accomplished by two Hewlett Packard 1000 computers. Custom software provides menu-driven programs for Instrument control, data retrieval and data analysis. 

Such modeling has been computerized (Qian and Kwauk, 1986) for on-line data acquisition and analysis for graphing -x curves directly from the automatic bed-collapsing instrument shown in Fig. 45. 

Elllpsometry. The automated ellipsometer is essentially equivalent to that described by Hauge and Dill ( 9). Data acquisition and analysis was made through the use of a Digital Equipment Corporation MINC 11/23 computing system. The detailed description of the system was reported previously ( 8). The measured ellipsometric angles and 4 are converted into the... 

Modem Dewar flask equipment includes an adiabatic shield, a compensation heater, and a computer to provide for control and for data acquisition and analysis. An example of the application of an advanced design is the adiabatic storage test (AST) [120,121]. In the AST, the heat generated at nearly adiabatic conditions by the reacting or decomposing substances is determined as a function of time. 

Of course if the required information is gathered from one particle at a time, it becomes necessary to make observations on a very large number of particles in order to properly characterize the assembly. It is therefore fortunate that the scanning mode of operation of the STEM instrument makes it ideally suited to the automated collection of data. Also the computer-based digital data acquisition and analysis systems are now reaching the state of sophistication which makes it possible to contemplate the necessary handling of large numbers of one- or two-dimensional arrays of data. 

The Malvern particle sizer is one of the most widely used, most effective, simple, and reliable methods commercially available for rapid measurements of ensemble characteristics of a spray. It is able to handle high droplet concentrations. It is easy to use and does not require comprehensive knowledge of its basic principles for operation. The primary advantage of the system is the speed of data acquisition and analysis. In addition, measurements of droplet size distributions can be made at any droplet velocities due to the fact that the diffraction patterns generated by droplets are independent of the... 

Novolac molecular weights were measured in THF at 35°C by high pressure size exclusion chromatography using a Waters Model 510 pump (flow rate=1.0 ml/min), 401 differential viscometer detector and a set of Dupont PSM 60 silanized columns. A universal calibration curve was obtained with a kit of 10 narrow molecular weight distribution, linear polystyrene standards from Toya Soda Company. Data acquisition and analysis were performed on an AT T 6312 computer using ASYST Unical 3.02 software supplied with the Viscotek instrument. 

Several types of imaging systems and associated software are commercially available for analyzing gels stained with just about any kind of stain.9(192 These instruments greatly simplify data acquisition and analysis and the archiving of gel patterns. 

Laboratory measurement procedures used for electrochemical data acquisition and analysis during the monitoring exercise are outlined, and particular emphasis is placed on the electrochemical noise techniques. Electrochemical current noise has been monitored between two identical electrodes and the potential noise between the working electrodes and a reference electrode. 

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