Main Advantages

Despite their decline in relative importance, and the lack of high-profile research interest, the outlook for the AFC is not so bleak. A number of companies in the United States, Canada, and Europe are all producing cells, and quietly getting on with building fuel cell businesses. The reason is that the AFC does have a number of clear and fundamental advantages over other types of fuel cells. 

Another advantage of great importance relates to the system cost. There are very few standard chemicals that are cheaper than potassium hydroxide. It really is a very low-cost material the electrolyte cost of the AFC is thus far less than any other type - and it always will be. Also, the electrodes, particularly the cathode, can be made from nonprecious metals, and no particularly exotic materials are needed. The electrodes are thus considerably cheaper than other types of fuel cells, and there is no reason to suppose this will change in the near future either. 

The final advantages are not quite so telling. We shall see in Section 5.5 that AFCs do not usually have bipolar plates. We have noticed in the previous chapter that these are a very significant contributor to the cost of the PEMFC, for example. This then has the benefit of reducing the cost, but it must be said that it is also an important cause of the lower power density of the AFC, in comparison with the PEMFC. 

Finally, it should be noted that while AFCs are usually fairly complex systems, they are generally somewhat less complex than the PEMFC. For example, the water management problem is considerably more easily solved. 

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The main advantage of this approach is that the designer can keep control of the basic decisions and interact with the design as it develops. By sta dng in control of the basic decisions, the intangibles of the design can be included in the decision making. 

The parametric method is an established statistical technique used for combining variables containing uncertainties, and has been advocated for use within the oil and gas industry as an alternative to Monte Carlo simulation. The main advantages of the method are its simplicity and its ability to identify the sensitivity of the result to the input variables. This allows a ranking of the variables in terms of their impact on the uncertainty of the result, and hence indicates where effort should be directed to better understand or manage the key variables in order to intervene to mitigate downside and/or take advantage of upside in the outcome. 

Overall, use of learning systems has two main advantages. First, the construction cost may be lower, certainly if the system is not construeted from scratch but uses existing software tools and components. Second, a learning system is able to adapt to changing conditions, though not always on-line. 

Case-based reasoning. The main advantage of CBR systems for NDT data interpretation is that they can cope with data coming from inspection of varying constructions under varying conditions with various system settings due to their ability to learn from the data classified by the operator. In such situations no reliahle statistical classifier can be designed, and the rule-hased classifiers would be either very inefficient or unpractically complex. 

Real Time Radiography (RTR) is an advanced method of radiography in which the image is formed while the job is exposed to ionising radiation. RTR is often applied to objects on assembly lines for rapid inspection. Accept-or-reject decisions may be made immediately without the delay or expense of film development. The main advantages of RTR are thus, reduction in inspection cost and processing time. 

Following table compares the main advantages of electrolytic desilvering versus cascade fixation. 

Finally, it is perfectly possible to choose a standard state for the surface phase. De Boer [14] makes a plea for taking that value of such that the average distance apart of the molecules is the same as in the gas phase at STP. This is a hypothetical standard state in that for an ideal two-dimensional gas with this molecular separation would be 0.338 dyn/cm at 0°C. The standard molecular area is then 4.08 x 10 T. The main advantage of this choice is that it simplifies the relationship between translational entropies of the two- and the three-dimensional standard states. 

The main advantage of tlie tln-ee-pulse ESEEM experiment as compared to the two-pulse approach lies m the slow decay of the stimulated echo intensity detemiined by T, which is usually much longer than the phase memory time Ty that limits the observation of the two-pulse ESE. 

Current drawn. LCDs usually draw small currents, wliich is one of their main advantages. 

Relational database models utilize memory very efficiently, avoiding repetition of data. It is possible to extract both individual data elements and combinations of them from a table. The main advantage of this structure is that it offers the possibility ofehanging the structure of the database (adding or deleting tables) without... 

One of the main advantages of the stochastic dynamics methods is that dramatic tirn savings can he achieved, which enables much longer stimulations to he performed. Fc example, Widmalm and Pastor performed 1 ns molecular dynamics and stochastic dynamic simulations of an ethylene glycol molecule in aqueous solution of the solute and 259 vvatc jnolecules [Widmalm and Pastor 1992]. The molecular dynamics simulation require 300 hours whereas the stochastic dynamics simulation of the solute alone required ju 24 minutes. The dramatic reduction in time for the stochastic dynamics calculation is du not only to the very much smaller number of molecules present hut also to the fact the longer time steps can often he used in stochastic dynamics simulations. 

VR, the inputs correspond to the value of the various parameters and the network is 1 to reproduce the experimentally determined activities. Once trained, the activity of mown compound can be predicted by presenting the network with the relevant eter values. Some encouraging results have been reported using neural networks, have also been applied to a wide range of problems such as predicting the secondary ire of proteins and interpreting NMR spectra. One of their main advantages is an to incorporate non-linearity into the model. However, they do present some problems Hack et al. 1994] for example, if there are too few data values then the network may memorise the data and have no predictive capability. Moreover, it is difficult to the importance of the individual terms, and the networks can require a considerable 1 train. 

Cyclopentene-l-carboxaldehydes are obtained from cyclohexene precursors by the sequence cyclohexene - cyclohexane-1,2-diol -> open-chain dialdehyde - cyclopentane aldol. The main advantage of this ring contraction procedure is, that the regio-and stereoselectivity of the Diels-Alder synthesis of cyclohexene derivatives can be transferred to cyclopentane synthesis (G. Stork, 1953 G. BUchi, 1968). 

The example clearly demonstrates the main advantages of solution chemistry over the solid-phase approach ... 

Extraction, a unit operation, is a complex and rapidly developing subject area (1,2). The chemistry of extraction and extractants has been comprehensively described (3,4). The main advantage of solvent extraction as an industrial process Hes in its versatiHty because of the enormous potential choice of solvents and extractants. The industrial appHcation of solvent extraction, including equipment design and operation, is a subject in itself (5). The fundamentals and technology of metal extraction processes have been described (6,7), as has the role of solvent extraction in relation to the overall development and feasibiHty of processes (8). The control of extraction columns has also been discussed (9). 

The main advantage of the VFD is that once the operating poiat of the fan is selected, that efficiency is carried at all speeds and flows. Capacity is directly related to motor frequency and thus to speed. Another important benefit is that as the fan speed decreases, fan noise and vibration also decrease significantly. 

The main advantage of HGMS is high efficiency of separation even at relatively high dow rates and minimum pressure drops across the filter. The capital cost is very high, and only large installations are attractive economically because capacity increases with the square of the diameter of the canister while the weight of copper conductor increases linearly with diameter. 

The main advantage of wholesale climate control Hes in easy access to the objects, and the absence of differences in conditions between various spaces within the institution, eg, storage areas, conservation laboratories, and exhibition galleries. The actual values set for the rh are a matter of compromise metals, stone, and ceramics are best served by humidities as low as possible, but organic materials generally require higher values. An accepted... 

There are two main advantages of acrylamide—acryUc-based flocculants which have allowed them to dominate the market for polymeric flocculants in many appHcation areas. The first is that these polymers can be made on a commercial scale with molecular weights up to 10—15 million which is much higher than any natural product. The second is that their electrical charge in solution and the charge density can be varied over a wide range by copolymerizing acrylamide with a variety of functional monomers or by chemical modification. 

A perforated plate can be flat, concave, convex, or double-dished. The main advantages of the perforated plate are that it is simple, inexpensive, easy to modify, and easy to clean. The disadvantages of a perforated plate are the possibiUty of soflds leaking, ie, weeping through it into the plenum lower turndown capabiUty than other distributors the requirement of a peripheral seal and a relatively high pressure drop requited for good distribution. 

Portabihty, simplicity, and high speed are the main advantages of this portable hardness tester. It uses a single numerical scale encompa ssing the hardness of ah metals. 

The main advantages of multilayer constmction are that it (/), reduces the risk of fragmentation (2), resists the growth of flaws from one layer to another and (2), enables leakage of the inner layer to be detected if the outer layers are provided with vent holes (53). 

Ca.ta.lysis by Protons. The discovery of hydrogen peroxide hydroxylation of phenol in the presence of strong acids such as perchloric, trifluoromethane-sulfonic, or sulfuric acids allows suppression of all previous drawbacks of the process (18,19). This mode of hydroxylation gives high yields (85% based on H2O2 at phenol conversion of 5—6%). It can be mn without solvents and does not generate resorcinol. Its main advantage rehes on... 

Main advantages of water inks include excellent press stability, printing quality, heat resistance, absence of fire hazard, and the convenience and economy of water for reduction and wash-up. 

The main advantages of ECM are that the rate of metal machining does not depend on the hardness of the material, compHcated shapes can be machined on hard metals, and there is no tool wear. 

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