Triangulation techniques

Some air-quality monitoring is designed for the specific purpose of investigating complaints concerning an unidentified source. This usually happens in urban situations for odor complaints. In these cases, a triangulation technique is used. By the use of this technique, human observers over a period of days can correlate the location of the observed odor and the direction of the wind. Plotting on a map can pinpoint the offending source in most cases. 

Passive triangulation techniques are very familiar to geodesists and photogrammetrists. The object is observed from two or more observation stations by direction measure- ments. For high precision determination of dimensional properties (such as coordinates, lengths,. ..) the object is normally described by targets, fixed at the object points being of interest. 

The alternate method uses the proximity probes and an oscilloscope. A Lissajous figure is established on the oscilloscope. The orbit pattern and the keyphase mark are used to generate a vector. Weights are added or removed and the changes in the orbit are noted. Triangulation is used to anticipate the next move. For more complete information or technique, the reader is referred to a book on the subject by Jackson [ 1 ]. 

Fractal Dimensions of the Profiles h(x) at Various Morphological Amplitudes rj in h(x) = 77/wsCv) Determined by the Current Transient Technique (2nd Column) and the Triangulation Method (3rd Column). Here, /ws(-v) Means the Weierstrass Function with a Self-Affine Fractal Dimension t/Fsa = 1.5 ... 

XsNv dp df Determined by the current transient technique dF.ss Determined by the triangulation method... 

Leggett et al (Refs 22 23) used a similar technique, except that their apparatus was static . TNT samples were placed in a 125ml vial equipped with silicone rubber septum cap. The vial was thermostatted and the sample and its vapor were allowed to equilibrate for 2—4 weeks. Vapor was withdrawn from the head-space with a stainless steel syringe and injected into a gas chromatograph. The concn of TNT in the headspace vapor was determined by manual triangulation of the peak, giving peak area/ volume, and dividing by the detector response factor (peak area/mass), as determined by injection of known quantities of TNT dissolved in benzene... 

A final point of consideration is the measurement time required. Certainly electronic integration is by far the fastest and the ball and disc integrator would also be considered fast. The manual methods in increasing slowness would be peak height, height and width, triangulation, planimeter, and finally cut and weigh technique. 

Within the radiation emission tracking techniques, there are two main variants positron emission, in which the tracer position is determined by triangulation as described in Section 2, and the "proximity" techniques, in which a gamma emitter is placed within the system of interest and its position found by measuring the relative count rates in an array of detectors. An example of the latter is computer-automated radioactive... 

A further increase in image-capture speed can be achieved through the use of more sophisticated illumination. This illumination can take on many forms, but is typically an array of dots or a set of projected lines. An image of the structured illumination shown on an object can then be processed in much the same way as triangulation data, but a full frame at a time. It generally only takes a handful of these full-frame images to describe a surface three-dimensionally, making structured illumination techniques extremely fast. 

The internal standard technique is based on the covariance term in the error propagation of this method 89) and avoids the error caused by applying small volumes to the plate. But there is another important aspect of error propagation in the comparison of internal and external standard methods. If the error in measurement is smaller than the error in spotting, the internal standard method is more precise than the external standard method 90>. However, if the error in measurement becomes dominant, the external standard leads to better results. This is the reason why in early quantitative TLC, where peaks had been triangulated and evaluated by the squared... 

Before a test is started, the coordinates of the flare and the radiometers (see Chapter 6) used to measure radiation are determined by utilizing a laser range finder to measure distances to three fixed objects with known coordinates and a technique called "triangulation." Multiple radiometers are used to measure various radiant fluxes simultaneously. A photo of the radiation measurement system is shown in Figure 28.12. The measured radiant fluxes, through sophisticated mathematical analysis, are used to determine the coordinates of the effective "epicenter(s)" of the flame, and the radiant fraction, which is defined as the fraction of heat release from combustion that is emitted as thermal radiation [43]. Solar radiation is subtracted from the radiation measurements as appropriate. 

Fig. 30. The 19 protein neutron map of the 30S ribosomal subunit determined by label triangulation (right). The proteins are depicted as spheres whose volumes are to scale. For clarity, several spheres are drawn unfilled. The centre-to-centre distance between S13 and S17 is 17.3 nm [490]. The left view shows the electron microscopy model of the 30S subunit and the sites of the antigenic determinants from immune electron microscopy techniques [490]. Note that most of the protein is located to the top of the model as viewed, while the RNA is predominant in the lower half.

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