Accuracy materials

Youden, W.J. (1961a), How To Evaluate Accuracy, Materials Research Standards, 1, 268-271. 

Range of instrument and manufacturer s accuracy Materials of construction, especially of process contact (wetted) parts Process connection details (e.g., chemical seals, capillary lengths, flange rating)... 

Murphy RB (1961) On the meaning of precision and accuracy. Materials Research and Standards, ASTM, Philadelphia, Pa., pp 264 267... 

Youden WJ (1961) How to evaluate accuracy, Materials research and standards. ASTM, Philadelphia, Pa. pp 268 271... 

Novatec developed accurate, sequential metering of up to four materials combined with blending. Figure 3.16 shows the principle of design. The dual load cell under the hopper assures weighing accuracy. Materials are delivered through accurate vibratory... 

The discussion tmderlines that non-AM processes are advantageous in terms of accuracy, material properties, reproducibihty, and, depending on the complexity of the part, buUd speed. This is especially true if the part s geometry is simple. 

From the above, it is clear that non-generative methods in regards to accuracy, material properties, reproducibility, and speed, depending on the geometry, may have advantages over generative processes. This is particularly true when the geometries... 

The accuracy of the calculated solution is highly depending of realistic values for conductivity and permeability of the tube material. While the conductivity can be found in the literature for most materials, the right permeability is harder to determine. In the RFEC technique the exciter current and thus the exciter field strength is often to high to assume a... 

Scaiming probe microscopies have become the most conspicuous surface analysis tecimiques since their invention in the mid-1980s and the awarding of the 1986 Nobel Prize in Physics [71, 72]- The basic idea behind these tecimiques is to move an extremely fine tip close to a surface and to monitor a signal as a fiinction of the tip s position above the surface. The tip is moved with the use of piezoelectric materials, which can control the position of a tip to a sub-Angstrom accuracy, while a signal is measured that is indicative of the surface topography. These tecimiques are described in detail in section BI.20. 

Toby B FI and Egami T 1992 Accuracy of pair distribution function analysis applied to crystalline and noncrystalline materials Aota Crystaiiogr.k 48 336-46... 

Computational solid-state physics and chemistry are vibrant areas of research. The all-electron methods for high-accuracy electronic stnicture calculations mentioned in section B3.2.3.2 are in active development, and with PAW, an efficient new all-electron method has recently been introduced. Ever more powerfiil computers enable more detailed predictions on systems of increasing size. At the same time, new, more complex materials require methods that are able to describe their large unit cells and diverse atomic make-up. Here, the new orbital-free DFT method may lead the way. More powerful teclmiques are also necessary for the accurate treatment of surfaces and their interaction with atoms and, possibly complex, molecules. Combined with recent progress in embedding theory, these developments make possible increasingly sophisticated predictions of the quantum structural properties of solids and solid surfaces. 

Every effort has been made to select the most useful and most reliable information and to record it with accuracy. However, the editor s many years of involvement with handbooks bring a realization of the opportunities for gremlins to exert their inevitable mischief. It is hoped that users of this handbook will offer suggestions of material that might be included in, or even excluded from, future editions and call attention to errors. These communications should be directed to the editor at his home address (or by telephone). 

Analytical chemists converse using terminology that conveys specific meaning to other analytical chemists. To discuss and learn analytical chemistry you must first understand its language. You are probably already familiar with some analytical terms, such as "accuracy and "precision, but you may not have placed them in their appropriate analytical context. Other terms, such as "analyte and "matrix, may be less familiar. This chapter introduces many important terms routinely used by analytical chemists. Becoming comfortable with these terms will make the material in the chapters that follow easier to read and understand. 

Consider the situation when the accuracy of a new analytical method is evaluated by analyzing a standard reference material with a known )J,. A sample of the standard is analyzed, and the sample s mean is determined. The null hypothesis is that the sample s mean is equal to p. 

Gases and vapors of volatile liquids can be introduced directly into a plasma flame for elemental analysis or for isotope ratio measurements. Some elements can be examined by first converting them chemically into volatile forms, as with the formation of hydrides of arsenic and tellurium. It is important that not too much analyte pass into the flame, as the extra material introduced into the plasma can cause it to become unstable or even to go out altogether, thereby compromising accuracy or continuity of measurement. 

Calibration of an arc or spark source is linear over three orders of magnitude, and detection limits are good, often within the region of a few micrograms per gram for elements such as vanadium, aluminum, silicon, and phosphorus. Furthermore, the nature of the matrix material composing the bulk of the sample appears to have little effect on the accuracy of measurement. 

Low accuracy, unsuitabiUty for commercial transactions Variations in material geometry and density affect accuracy... 

Belt-conveyor scales determine the amount of material being conveyed on a belt. A section of belt is weighed by placing the belt support rollers on a scale the belt speed is also measured. Weight and speed data are suppHed to a controller which integrates them to arrive at a material flow rate, often stated in tons per hour. The controller may display a flow rate, shut the conveyor down when a predeterrnined amount of material has passed, or it may be used to maintain a specified flow rate. Accuracy is limited because of the number of detrimental influences involved, eg, variable belt tension. 

Some of the various methods of weighing the material in a railroad car, arranged approximately in increasing order of accuracy, are ... 

Cahbration can also be accompHshed usiag material weighed on another scale. The accuracy of this method depends on the accuracy of the other scale, and care must be taken not to lose any of the weighed material. Scales can also be caUbrated electrically usiag a load cell simulator if the load cells rated outputs are known accurately. This method does aot test the mechanical fiinctioning of the scale and is not very accurate, particularly if it has attached piping that restricts its vertical movement. 

---