Odor classification

AmooreJE, Odor theory and odor classification, iniTheimer ET (ed.). Fragrance Chemistry, The Science of the Sense of Smell, Academic Press, New York, USA, pp. 21-IS, 1982. 

It has been suggested that these anosmias refer to a primary odor classification. These olfactory sensitivity differences could potentially contribute significant differences in flavor perception among individuals for a given product. 

Borjesson, T., Eklov, T., Jonsson, A., Sundgren, H., Schnurer, J. (1996) Electronic nose for odor classification of grains. Cereal Chem. 73 457-461. 

The remainder of this chapter is organized into 3 sections discussing the fan-out properties of PN to KC connections and the AL-MB system as a classification machine (section 1.2), more detailed models of the AL-MB classification system (section 1.3) and an analysis of lateral connections between KCs in the MB for time integration (section 1.4). I will close with a general discussion of the implications of these results for biomimetic approaches to odor classification and pattern classification in general. 

In summary, we have seen that if parameters (connectivity degree and firing threshold) are chosen wisely, fully random connections allow an almost always (in the loose sense of a very small failure probability) one-to-one projection of activity patterns from the AL to the MB, a necessary requirement for successful odor classification. At the same time, the activity level in the MB can remain reasonably low even though the absolute minimum for the confusion probability is attained at very high activity levels. 

In summary, the more detailed models reveal how the nervous system of the locust may implement the elements of the odor classification scheme with random connections using simple elements like mutual all-to-all inhibition and Hebbian learning. We have also seen that the implementation of classification with these simple ingredients automatically solves the additional task of detecting the cluster structure of the input pattern set. 

Combining the expressions (l.C2)-(l.C5) gives the full expression for P(r = 0) and was used to generate the one-odor classification results in Figure 1.3. 

Kaeppler K, Mueller F (2013) Odor classification a review of factors influencing perception-based odor arrangements. Chem Senses 38(3) 189-209. doi 10.1093/chemse/bjsl41... 

Should the system be placed in an environment of interest, the learning algorithm of the SOM network processes the sensor outputs step by step, providing a statistical identification of the environment in an unsupervised fashion, i e without any supplementary information other than that supplied by the sensor array [2] Odor classification is accomplished exploiting a set of internal synthetic categories, which is recursively constructed by the network during the lifetime of the system This set contains a model of each kind of odor detected by the sensor array, whose accuracy is weighted on the basis of the statistical recurrence of the odor... 

F A M Davide, C Di Natale, A D Amico, Self-Orgamzing multisensor systems for odor classification internal categonzation, adaption and drift, Sensors and Actuators B, 18, 1-3, (1994),244-258... 

Bicego used the similarity-based representation of electronic nose measurements for odor classification with the SVM method.In the similarity-based representation, the raw data from sensors are transformed into pairwise (dis)similarities, i.e., distances between objects in the dataset. The electronic nose is an array of eight carbon black-polymer detectors. The system was tested for the recognition of 2-propanol, acetone, and ethanol, with 34 experiments for each compound. Two series of 102 experiments were performed, the first one with data recorded after 10 minutes of exposure, whereas in the second group of experiments, the data were recorded after 1 second of exposure. The one-versus-one cross-validation accuracy of the first group of experiments was 99% for similarity computed using the Euclidean metric. For the second group of experiments, the accuracy was 79% for the Euclidean metric and 80% for the Manhattan metric. 

M. Bicego, Sens. Actuators B, 110, 225-230 (2005). Odor Classification Using Similarity-... 

Odor perception and description are highly subjective in nature. Nevertheless, there is a generally agreed-upon odor vocabulary that is used to characterize individual ingredients and finished fragrances. Table 1 shows some commonly used odor descriptors grouped into five general classifications. 

Completely Denatured Alcohol. Completely denatured alcohol (CD A) escapes the involved financial and administrative controls required of the other classifications of industrial ethanol. No tax is appHed, no bond is required, no permit is needed to enable a customer to purchase CD A. Requirements for records by both producer and user are minimal. These simplified regulations are possible because CDA is denatured with substances that render it totally unfit for beverage purposes. It is also unsuitable where odor is objectionable. CDA and products made from it are, however, governed by special labeling requirements of the BATE. Repackaging of completely denatured alcohol is permitted as long as labeling requirements are met. 

Four characteristics of odor are subject to measurement by sensory techniques intensity, detectability, character (quality), and hedonic tone (pleasantness-unpleasantness) (16). Odor intensity is the magnitude of the perceived sensation and is classified by a descriptive scale, e.g., faint-moderate-strong, or a 1-10 numerical scale. The detectability of an odor or threshold limit is not an absolute level but depends on how the odorant is present, e.g., alone or in a mixture. Odor character or qualit) is the characteristic which permits its description or classification by comparison to other odors, i.e., sweet or sour, or like that of a skunk. The last characteristic is the hedonic type, which refers to the acceptability of an odorant. For the infrequent visitor, the smell of a large commercial bread bakery may be of high intensity but pleasant. For the nearby resident, the smell may be less acceptable. 

Odors possess many classifications. There are 20 of them commonly used, all possessing rather picturesque names. In fact the names, in many cases, are far more pleasant than the odors themselves. To name a few of them - nasturtium, cucumber, geranium, fishy, pigpen, earthy, grassy and musty. Authorities further classify these odors in terms of their intensity from very faint, faint, distinct and decided... 

Hydrocarbons are divided into two main classes aliphatic and aromatic. This classification dates from the nineteenth century, when organic chemistry was devoted almost entirely to the study of materials from natural sources, and terms were coined that reflected a substance s origin. Two sources were fats and oils, and the word aliphatic was derived from the Greek word aleiphar meaning ( fat ). Aromatic hydrocarbons, ine-spective of their- own odor, were typically obtained by chemical treatment of pleasantsmelling plant extracts. 

In the last decade much effort has been oriented to the fabrication of artificial olfaction machines able to determine chemical images (also odor images) of complex volatile compounds. Today many different electronic noses and tongues are available for odor detection and classification and for the creation of chemical images of liquids. 

Water Reclamation Works by their very nature can, at times be the source of unpleasant odorous emission. The odour-intensive compounds (osmogenes) which make up these emissions are believed to arise mainly as the decomposition products of carbohydrates and proteins. The breakdown of this waste material proceeds by aerobic and anaerobic processes at various stages of the treatment plant. Atmospheric pollution of this nature frequently results in complaints from members of the public either resident, or perhaps employed in the vicinity of such works. In order to confirm or deny that a reclamation works is responsible for a particular nuisance and, if possible to identify the causal agents it was decided that the Authority should have the capability of analysing for odorous and other polluting constituents of the atmosphere. This paper describes the progress made towards this objective and summarises the experience gained with a procedure in use. There are two principle approaches available for the analytical classification of odorous emissions -... 

Sachs, B. D. (1999). Airborne aphrodisiac odor from estrous rats implications for pheromonal classification. InAdvances in Chemical Signals in Vertebrates, vol. 8, ed. R. E. Johnston, D. Miiller-Schwarze, and P. W. Sorensen, pp. 333-342. New York Kluwer Academic-Plenum. 

A much-simplified classification, based on these tables, is shown in Table 4.6. The scale of interest is very different for trace chemical or odor plumes from that for which the original classification system was developed. Therefore, it is proposed that the simplified classification scheme of Table 4.6 will be sufficiently applicable to provide an indication of the more and the less favorable conditions for following plumes. In this presentation the lighter shading denotes those conditions that are generally more favorable darker shading indicates more instability and hence less well defined plumes. 

The odors of single chemical compounds are extremely difficult to describe unequivocally. The odors of complex mixtures are often impossible to describe unless one of the components is so characteristic that it largely determines the odor or flavor of the composition. Although an objective classification is not possible, an odor can be described by adjectives such as flowery, fruity, woody, or hay-like, which relate the fragrances to natural or other known products with similar odors. 

In an attempt to use the chemical constituents of the Quararibea-Matisia complex as an aid in their classification, these simple testing procedures were applied to 20 Central American samples representing either of the two genera. The highly odorous furanones, as well as positive alkaloid tests, were noted in 13 of these samples and absent in seven. The suggestion is that the former represent... 

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