The functional structure of our new network is not preset; instead, it
comes into existence in a random, stochastic manner.
The anatomical structure of our model consists of two input “neurons”, hundreds up to five thousands of hidden-layer “neurons” and one output “neuron”.
The proper process is based on iteration, i.e., mathematical operation governed by a set of rules, in which repetition helps to approximate the desired result.
Each iteration begins with data being introduced into the input layer to be processed in accordance with a particular algorithm in the hidden layer; it then continues with the computation of certain as yet very crude configurations of images regulated by a genetic code, and ends up with the selection of 10% of the most accomplished “offspring”. The next iteration begins with the application of these new, most successful variants of the results, i.é., descendants in the continued process of image perfection. The ever new variants (descendants) of the genetic algorithm are always generated randomly. The determinist rule then only requires the choice of 10% of all the variants available (in our case 20 optimal variants out of 200).
The stochastic model is marked by a number of characteristics, e.g., the initial conditions are determined by different data dispersion variance, the evolution of the network organisation is controlled by genetic rules of a purely stochastic nature; Gaussian distribution noise proved to be the best “organiser”.
Another analogy between artificial networks and neuronal structures lies in the use of time in network algorithms.
For that reason, we gave our networks organisation a kind of temporal development, i.e., rather than being instantaneous; the connection between the artificial elements and neurons consumes certain units of time per one synapse or, better to say, per one contact between the preceding and subsequent neurons.
The latency of neurons, natural and artificial alike, is very importaiit as it
enables feedback action.
Our network becomes organised under the effect of considerable noise. Then, however, the amount of noise must subside. However, if the network evolution gets stuek in the local minimum, the amount of noise has to be inereased again. While this will make the network organisation waver, it will also inerease the likelihood that the erisis in the local minimum will abate and improve substantially the state of the network in its self-organisation.
Our system allows for constant state-of-the-network reading by ineaiis of establishing the network energy level, i.e., basically ascertaining progression of the network’s rate of success in self-organisation. This is the principal parameter for the detection of any jam in the local minimum. It is a piece of input information for the formator algorithm which regulates the level of noise in the system.
Impaired wakefulness in machine operators poses a danger not only
to themselves but often also to the public at large. While on duty, such persons are expected to be continuously, i.e., without interruption, on the alert. For that purpose, we designed and carried out an experimental model of continuons vigilance monitoring using electroencephalography (EEG) and reaction time measured as the latency of the probanďs reaction to sound. If constructed, the set together with other logical elements and an alarm can make for an automatic detection of vigilance and, possibly, also of arousal stimuli in cases of microsleep. We have found the following new facts and coníirmed the validity of some of the earlier ones.
Impaired wakefulness in machine operators poses a danger not only to themselves but often to the public at large as well. While on duty, such persons are expected to be continuously, i.e., without interruption, on the alert. For that purpose, we designed and carried out an experimental model of continuous vigilance monitoring using electroencephalography (EEG) and reaction time measured as the latency of the probanďs reaction to sound stimulus. If constructed, the set together with other logical elements and an alarm systém can be used for an autornatic detection of vigilance and, possibly, also of arousal stimuli in cases of micro-sleep.
Transportation of people and goods represents a still more significant
component of the human culture. Its influence is extremely high today and will increase greatly in the future.
Almost all the contemporary transportation systems are based on the necessity of interaction between the transportation tool (vehicle, plane, ship), the transport control system and the human subject. Though a large effort is put into the development of automatic transport systems, none of the present attempts is fully automatic, in all of them the human subject plays a non-neglectable role with considerably high impact on the reliability and safety of the transportation function. Among such functions the driving and control activity dominates.
The drivers, pilots, captains and transportation systems dispatchers and controllers are usually exposed to considerably long and exhausting Services, which could last up to 8 and even more hours.
It is generally known that the human subject is not able to retain in the state of vigilance without brakes and relaxation. Usually, its ability to concentrate his/her attention to some activity (like driving of systém control) decreases considerably soon, mainly after 45 or 60 niinutes only.
The decrease of human subject attention in the course of his/her activity is not monotone of course, it can involve several periods of temporary increases and decreases. However, without exception, if the exposition is long enough, the subject attention finally falls under the limit of acceptability for safe and reliable activity of the particular type. The subject activity becomes dangerous for him/her, his/her environment and for the driven vehicle, plane, ship or the controlled transportation system too. Finally, the subject falls in the stage of the so-called micro-sleep, in which he/she is not able to produce the particular driving or control activity at all.
A considerably large effort was given to the analysis of negative impacts of this factor. Unfortunately, the used methodology for such analyses differs up to now in many countries, so that the results are not quite comparable. However, one can estimate that between 15 and 40% of all the accidents on the roads are caused by the non-satisfactory level of the human subject attention. If we take into account that the average economic loss of one mortal road accident is estimated to more than 1 million Euro and if the density of such accidents is taken into account as well, we come to a tremendous figure, which has to be enlarged more by the estimation of losses of non-mortal accidents.
Electric and metabolic brain activities were controlled for 49 persons by means of electroencephalography (EEG) and near infrared spectroscopy (NIRS) during different physiological and psychological states, e.g. eyes open or closed, hyperpnoea (HV) or apnoea (AP) and during calculation (addition of one- (CAL.S.) or two-digit numbers (CAL C.)) or Raven's test - set A (RAV A) or more difficult set C (RAV C) or TAT. Both diagnostic methods confirm one another. But sometimes there are more expressive changes in one method than in another, e.g. during HV it is a more prominent deoxyhemoglobin (CO2Hb) increase than an alpha frequency band increase in EEG curves. On the other side, very marked alpha frequency decreasing in EEG during eyes open is followed by only a weak oxyhemoglobin (O2Hb) rise. Synchronous activities are clearly visible during psychic test: increasing O2Hb in NIRS and increasing delta frequency band in EEG spectrum. Decreasing alpha with increasing theta activity during relaxation and somnolence is accompanied by decreasing O2Hb and prominent increasing CO2Hb. Inter individually differences are often but not big. We suggest both methods are good tools for attention and psychic states control.
In this paper, an extended analysis of the human electroencephalographic signals (EEG) in the region of alpha rhythms is presented. The consequences of the existence of spindle-like (fusiform) shape are discussed and verified on the set of experimental measurements. The hypothesis of possible interrelations of the EEG alpha fuses with a tested person's psychical state and restrictions is presented.