Attempting a Definition

Considering everything we heard about expert systems, we can attempt to define some minimal requirements that would constitute an expert system, or a knowledge-based system  

On the other hand, expert systems are not necessarily developed in descriptive programming languages as long as they are able to present the knowledge in a descriptive manner. Expert system shells and descriptive languages are merely tools that allow — in some, but not all cases — development to be done more efficiently. 

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An early method that attempted a definitive classification of coals on the basis of their composition and heating value was based on the ratio of the fixed carbon to the volatile combustible matter (C/V.Hc) (Frazer, 1877) in which the ratio of the volatile to fixed combnstible matter was a logical basis for the classification of coals. After various attempts to make the fuel ratio of the different coals fit the descriptions of the varieties of coal, it was concluded that coal could be classified according to the fuel ratio within wide limits, and the following divisions were snggested ... 

Endoscopy cannot assess motility adequately. An oesophagus may appear dilated and amotile, but formal assessment is not possible as the primary wave progression cannot be followed, and the presence of the endoscope may interfere with function. Endoscopists are of course fully aware of this limitation and would not attempt a definitive motility diagnosis. However, some motility disorders will present with symptoms similar to those caused by structural lesions, and a motility cause maybe overlooked. Patients with dysphagia maybe investigated for years before a diagnosis of achalasia (Fig. 4.10) is entertained, which could have been achieved by simple barium swallow. 

For larger masses, the possibilities increase enormously. At mass 100, there would be literally thousands of possible elemental compositions so that, although integer mass can be measured mass spectromet-rically, attempts to obtain elemental compositions will not lead to a definite answer. 

Servos gives a beautifully clear explanation of the subject-matter of physical chemistry, as Ostwald pursued it. Another excellent recent book on the evolution of physical chemistry, by Laidler (1993) is more guarded in its attempts at definition. He says that it can be defined as that part of chemistry that is done using the methods of physics, or that part of physics that is concerned with chemistry, i.e., with specific chemical substances , and goes on to say that it cannot be precisely defined, but that he can recognise it when he sees it Laidler s attempt at a definition is not entirely satisfactory, since Ostwald s objective was to get away from insights which were specific to individual substances and to attempt to establish laws which were general. 

Some auditors believe that any document generated or used by the quality system is a quality record and will attempt to apply the requirements of clause 4.16. Whilst it can be argued that any documented output is a record of an activity, the reader is referred to ISO 8402 for a definition of records in the context of the quality system. ISO 8402 states that a record is a document which furnishes objective evidence of activities performed or results achieved. A quality record provides objective evidence of the fulfillment of the requirements for quality (e.g. product quality record) or the effectiveness of the operation of a quality system element (e.g. quality system record). 

This is in contrast to many data collection systems, in which considerable efforts are expended in developing a "definitive" data collection philosophy. However, once the system is in place, there is little attempt to modify this on the basis of operational feedback. 

Is it possible or not to improve the accuracy in r without essential modifications of the composite Cauchy problem In an attempt to give a definite answer to this question, the composite Cauchy problem (55) is designated by the symbolism... 

It can be seen that these definitions are derived from experimental observation and are no more than classifications based on a set of properties shared by a group of substances. They are scientifically inadequate for the interpretation of results, which requires a definition based on concepts. Historically, the attempt to provide a model rather than a classification comes in the form of a search for imderlying universal principles. It seems that the alchemists recognized vague principles of acidity and alkalinity, and in the 17th century the iatrochemists made these the basis of chemical medicine. Disease was attributed to a predominance of one or other of these principles (Pattison Muir, 1883). 

Attempts to determine how the activity of the catalyst (or the selectivity which is, in a rough approximation, the ratio of reaction rates) depends upon the metal particle size have been undertaken for many decades. In 1962, one of the most important figures in catalysis research, M. Boudart, proposed a definition for structure sensitivity [4,5]. A heterogeneously catalyzed reaction is considered to be structure sensitive if its rate, referred to the number of active sites and, thus, expressed as turnover-frequency (TOF), depends on the particle size of the active component or a specific crystallographic orientation of the exposed catalyst surface. Boudart later expanded this model proposing that structure sensitivity is related to the number of (metal surface) atoms to which a crucial reaction intermediate is bound [6]. 

Infrared spectroscopy is a major tool for polymer and rubber identification [11,12]. Infrared analysis usually suffices for identification of the plastic material provided absence of complications by interferences from heavy loadings of additives, such as pigments or fillers. As additives can impede the unambiguous assignment of a plastic, it is frequently necessary to separate the plastic from the additives. For example, heavily plasticised PVC may contain up to 60% of a plasticiser, which needs to be removed prior to attempted identification of the polymer. Also an ester plasticiser contained in a nitrile rubber may obscure identification of the polymer. Because typical rubber compounds only contain some 50% polymer direct FUR analysis rarely provides a definitive answer. It is usually necessary first... 

Therefore any attempt to model the spatial occurrence and fate of chemicals in the environment will require an appropriate choice of all the factors discussed above, which have a definite influence on the behavior of the chemicals considered. Figure 2 summarizes some of the most relevant. It is worth mentioning that the availability of spatial data sets has been greatly enhanced by the current progress achieved on remote sensing technologies [57, 58]. 

Danzer K (2001) Selectivity and specificity in analytical chemistry. General considerations and attempt of a definition and quantification. Fresenius J Anal Chem 369 397... 

To define a borderland like this is by no means an easy task the boundary shifts from year to year yet a definition of the present aims of Physical chemistry may be made. We may say that the object of physical chemistry is to attempt to refer chemical changes to action between atoms and molecules and to investigate such action as regards its rate, and its extent. (Ramsay 1893 , 1)... 

A further successful attempt to detect a,(3-unsaturated SPC (SPC-2H) during the degradation of LAS was achieved by Eichhorn and Knepper [34] (Fig. 5.1.8). An SPC-2H has m/z of two mass units below that of the corresponding SPC, and compounds of this type have been described in the degradation of impurities in LAS, the monocarboxylated DATS [88,104]. However, a definite distinction between the known DATS carboxylates [88] and the putative SPC-2H could be provided by LC-ESI-MS analysis, which enabled structural assignment via... 

An early attempt to resolve the discrepancy between the high values of Sugimura and Suzuki (1988) and more traditional analyses failed to reach a definitive conclusion (Williams, 1992). The start of the Joint Global Ocean Flux Study (JGOFS) field program with the North Atlantic Bloom Experiment in 1989 put additional pressure on the various groups to resolve this issue quickly. The National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA) funded a workshop held in Seattle in July 1991 to resolve the issue. 

If an attempt is made to define burning velocity strictly for such a system, it is found that no definition free from all possible objections can be formulated. Moreover, it is impossible to construct a definition that will, of necessity,... 

This was attempted by Hoffman and co-workers, who studied the influence of a porphyrin vinyl group on the electron transfer rate in a [Fe, Zn] hybrid hemoglobin [149]. In this study, the chemical modification was simply achieved by preparing the hybrid with Zn deuterioporphyrin. However, entropic contributions are unknown in this system, and activation energies could not be accurately measured. Both effects preclude an accurate determination of the nuclear factor and a definitive attribution of the observed variations to the sole electronic factor. 

This present book is no more than an introduction to electroanalytical chemistry. It is not a textbook, but is intended for those wanting to learn at a distance, or in the absence of a suitable tutor. Accordingly, the approach taken is that of a series of tutorial questions and worked examples, interspersed with questions for students to attempt in their own time. In no way is this meant to be a definitive text students who have mastered these topics are recommended to consult the books and articles listed in the Bibliography at the end. 

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