Data acquisition, principles

DATA ACQUISITION PRINCIPLES FROM TRANSDUCERS TO COMPUTERS... 

Instruments based on the contact principle can further be divided into two classes mechanical thermometers and electrical thermometers. Mechanical thermometers are based on the thermal expansion of a gas, a liquid, or a solid material. They are simple, robust, and do not normally require power to operate. Electrical resistance thermometers utilize the connection between the electrical resistance and the sensor temperature. Thermocouples are based on the phenomenon, where a temperature-dependent voltage is created in a circuit of two different metals. Semiconductor thermometers have a diode or transistor probe, or a more advanced integrated circuit, where the voltage of the semiconductor junctions is temperature dependent. All electrical meters are easy to incorporate with modern data acquisition systems. A summary of contact thermometer properties is shown in Table 12.3. 

Method principles should include the technique used for mass spectral data acquisition. 

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... 

In section 3.2 the main principles of ID and 2D NMR experiments are brielly discussed and some typical examples are shown. It is not the aim of this book to give you an introduction into the mechanics of multiple pulse experiments or the gymnastics of spins in such experiments. If you are interested in the physics and the experimental aspects of the various NMR experiments you are referred to Data Acquisition (volume 2) of this series, where these topics are discussed in detail. 

The principle of presaturation relies on the phenomenon that nuclei which are unable to relax, because their population in the ground state a and the excited state (3 is the same, do not contribute to the free induction decay after pulse irradiation. Prior to data acquisition, a highly selective low-power pulse irradiates the desired solvent signals for 0.5 to 2 s, thus leading to saturation of the solvent signal frequency. During data acquisition, no irradiation should occur. NOESY-type presaturation is an effective pulse sequence of presaturation. The pulse sequence consits of three 90° pulses (similar to the first increment of a NOESY experiment) ... 

In the following sections, we explain the basic principles of NEXAFS, methods of data acquisition and analysis, and its application to NOM. 

A new method of surface tension determination has been developed which is continuous, automated, compatible with computer data acquisition systems, and capable of monitoring flowing process streams. The method is a variant of the well-known maximum bubble pressure technique. To illustrate the principles, we will describe the simplest initial configuration of the instrument here. Further details and a description of a refined version of the instrument will be reported later. 

In other sections of this volume,6 detailed discussions on the principles of data acquisition for IR spectral imaging are presented (Chapter 1, this volume). Here, we shall restrict ourselves to a description of the instrumentation used for the research described in the following review. 

In this article we try to give a survey on fundamental principles of data acquisition. As it is certainly beyond the scope of this text to present a thorough representation of the technical details and tricks involved in data acquisition we intend to show the capabilities and limits of digital data acquisition and to provide some explanation of the technical terms involved. In order to get a closer view of this topic the interested reader should also take a look into textbooks (ref. 1-5). 

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