Field test

In field-test situations, test chemicals are applied to large areas under natural conditions. The areas are at least several acres and may be either natural or part of some agroecosystem. Because the area is large and in the open, radiolabeled compounds cannot be used, it is not possible to obtain a balance between material applied and material recovered. 

The effects are followed over a long period of time and two types of control may be used first, a comparison with a similar area that is untreated and second, and a comparison with the same area before treatment. In the first case it is difficult, if not impossible, to duplicate exactly a large natural area, and in the second, changes can occur that are unrelated to the test material. 

Field tests are analytical tests that are normally carried out outside the laboratory (in the field ). Field tests for explosives are usually performed when a rapid, on-site diagnostic detection of explosive materials is required. Thus, they are often carried out on suspects hands and belongings, in post-explosion sites, or in border stations, seaports, and airports. It should be emphasized that they constitute only prehminary examinations, and positive results should not be presented to court unless confirmed by reliable laboratory methods. Because field tests are usually carried out by individuals with no scientific background, their application must be easy, involving simple equipment and methodology. 

In forensic laboratories, chemical spot tests based on color reactions, have been replaced over the years by modem, more accurate instrumental methods. However, analytical techniques based on color formation are stiU commonly employed in field tests for explosives. Being inexpensive, simple, easy-to-operate and often quite sensitive (see above), they are most suitable for use outside the laboratory as presumptive field tests for the presence of explosives. 

Several kits for explosives detection, which are based on color reactions, were reported or introduced commercially. Some of those that have been surveyed by the chemical ftterature are described in this chapter. This is by no means an exhaustive ftst. Many other kits, some of which are commercially available, but have not appeared in peer-reviewed journals, can be found by searching the web. 

A kit for detecting explosives on suspects hands or clothing — Explosives Handling Detection Kit — was developed by Newhouser and Dougherty in 1972 [96]. It was designed to detect three types of explosives, defined by the authors as TNT-based explosives, RDX-based explosives, and NG- 

The original ETK has been modified for improved sensitivity and stability [97]. Another version applying the same reagents from spray cans instead of dropping-bottles (Expray ) is also commercially available [98]. 

A number of experiments have now been carried out to apply or test canopy-scale inverse methods in the field (Raupach et al., 1992 Denmead and Raupach, 1993 Denmead et al, 1997 Katul et al, 1997, 2000 Leuning et al, 2000 Leuning, 2000 Denmead et al, 2000 Harper et al, 2000) with generally good results. Many, but not all, of these have used LNF theory to obtain D-,.  

FIGURE 5 Comparison of time series for the upward fluxes of latent heat (A ) and CO2 above a rice canopy on 8 August 1996 (a and c) and 11 August 1996 (h and d), from the EC and IL methods (after Leuning, 2000). 

In summary, these experiments indicate that the IL method can yield practically useful information about canopy source distributions from atmospheric concentration measurements. However, the method depends on several factors, any of which may be limiting (1) measured concentration profiles of sufficient accuracy and density in the vertical dimension (2) adequate and sufficiently accurate measurements of the turbulence field (3) an adequate theory of turbulent transport and dispersion in canopies, to calculate the dispersion matrix (4) an adequate procedure for doing the inversion itself Evidence presented in the next subsection indicates that all of these aspects can be combined successfully, though there is uncioubtecfly room for improvement especially in the latter two fiictors. 

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For each field test, a procedure for the AE monitoring is established. 

An important and expensive problem in surface science occurs in the prevention of the attachment of marine animals such as barnacles to ship surfaces, a process known as biofouling. Baier and Meyer [159] have shown that the Zisman plot can be used to predict biofouling, thus avoiding costly field tests to find a successful coating to prevent biofouling. 

Concern for personnel exposure to hydrazine has led to several innovations in packaging to minimize direct contact with hydrazine, eg, Olin s E-Z dmm systems. Carbohydrazide was introduced into this market for the same reason it is a soHd derivative of hydrazine, considered safer to handle because of its low vapor pressure. It hydrolyzes to release free hydrazine at elevated temperatures in the boiler. It is, however, fairly expensive and contributes to dissolved soHds (carbonates) in the water (193). In field tests, catalyzed hydrazine outperformed both hydrazine and carbohydrazide when the feedwater oxygen and iron levels were critical (194). A pubUshed comparison is available (195) of these and other proposed oxygen scavengers, eg, diethyUiydroxylarnine, ydroquinone, methyethylketoxime, and isoascorbic acid. 

Alcohol ethoxysulfates have been used in field tests as nitrogen (177) and carbon dioxide (178) foaming agents. Field use of alcohol ethoxysulfates is restricted to low temperature formations owing to its limited hydrolytic stabihty at low pH and elevated temperature (179). It has been reported that some foams can reduce residual oil saturation, not by oil displacement, but by emulsification and imbibition of the oil into the foam (180). 

Including a surfactant in the caustic formulation (surfactant-enhanced alkaline flooding) can increase optimal salinity of a saline alkaline formulation. This can reduce iaterfacial tension and increase oil recovery (255,257,258). Encouraging field test results have been reported (259). Both nonionic and anionic surfactants have been evaluated in this appHcation (260,261). 

Prevention of Soil Crusting. Acid-based fertilizers such as Unocal s N/Furic (a mixture of urea with sulfuric acid), acidic polymers such as FMC s Spersal (a poly(maleic acid) derivative originally developed to treat boiler scale) (58), the anionic polyacrylamides described previously, as weU as lower molecular weight analogues such as Cytec s Aerotil L Soil Conditioner, have all been used successfully in at least some circumstances to prevent the formation of soil cmsts. It is difficult to prove benefits in the laboratory, and field tests may give variable results depending on local weather conditions. 

Micellar/polymer (MP) chemical enhanced oil recovery systems have demonstrated the greatest potential of all of the recovery systems under study (170) and equivalent oil recovery for mahogany and first-intent petroleum sulfonates has been shown (171). Many somewhat different sulfonate, ie, slug, formulations, slug sizes (pore volumes), and recovery design systems were employed. Most of these field tests were deemed technically successful, but uneconomical based on prevailing oil market prices (172,173). 

A. L. Almerini and S. J. Bartosh, "Simulated Field Tests on Zinc—Air Batteries," Proceedings of the 26th Power Sources Symposium, Adantic City, N.J.,... 

Acrylamide—polymer/Ct(III)catboxylate gel technology has been developed and field tested in Wyoming s Big Horn Basin (211,212). These gels economically enhance oil recovery from wells that suffer fracture conformance problems. The Cr(III) gel technology was successful in both sandstone and carbonate formations, and was insensitive to H2S, high saline, and hard waters (212). 

Disinfection tests can be classified according to the test organism, ie, whether the test employs certain species of bacteria, fungi, or vimses classified as to whether it is a static test or a cidal test, as in a bactericidal vs bacteriostatic test or sporicidal vs sporistatic test or classified as to whether it is a microbial reduction test or an end-point test where all the organisms in the test are apparently killed. Procedures may be distinguished by in vitro or in vivo testing. Another way to consider tests is whether they are screening tests, practical type laboratory tests, or field tests. 

Field Testing. Field tests caimot be readily standardized because the fields of use are different from each other, as are the sources of... 

In field testing, there are many commercial products and instmments available that ate helphil in rapidly detecting, identifying, and quantifying micro organisms. 

Currently, over 110,000 t/yr of engineering resin blends are consumed worldwide, primarily in the transportation, business-machine, hardware, electrical, and appHance industries. Annual growth is projected to be ca 17%/yr. New blends based on PC, terephthalate, and nylon resins are experiencing the greatest expansion (122). These projections could be surpassed if large-volume metal appHcations such as automotive panels are replaced by engineering resin blends which are currently being field-tested. 

During the 1980s, several adaptive controllers were field-tested and commerciahzed in the U.S. and abroad, including products by ASEA (Sweden), Leeds and Northrup, Foxboro, and Sattcontrol. At the present time, some form of adaptive tuning is available on almost all PID controllers. The ASEA adaptive controller, Novatune, was... 

The subject of adaptive control is one of current interest. New algorithms are presently under development, but these need to be field-tested before industrial acceptance can be expected. It is clear, however, that digital computers will be required for implementation of self-adaptive controllers due to their complexity. An adaptive controller is inherently nonlinear and therefore more complicated than the conventional PID controller. 

Because many of the techniques, especially those associated with the recovery of materials and energy and the processing of solid hazardous wastes, are in a state of flux with respect to application and design criteria, the objective here is only to introduce them to the reader. If these techniques are to be considered in the development of waste-management systems, current engineering design and performance data must be obtained from consultants, operating records, field tests, equipment manufacturers, and available literature. 

Many computer codes, both public and private, are available to model dense cloud dispersion. A detailed review of these codes, and how they perform relative to actual field test data, is available (Hanna, Chang, and Strimaitis, Atmospheric Environment, vol. 27A, no. 15, 1993, pp. 2265-2285). An interesting result of this review is that a simple nomograph method developed by Britter and McQuaid (1988) matches the available data as well as any of the computer codes. This method will be presented here. 

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