Complex Probabilistic Systems Research Articles

ПРОМИСЛОВИЙ ЦИКЛОННО-РОТАЦІЙНИЙ ПИЛОВЛОВЛЮВАЧ

Cyclone equipment is easy to manufacture and operate, versatile and economical, but its main drawback is the inability to capture finely dispersed dust. The article discusses the most important characteristics of the highly efficient industrial cyclonic rotary dust collector developed by us. The apparatus implements the principle of two-stage separation of heterogeneous dust-gas systems in a centrifugal field. In the first stage, working on the principle of a cyclone, and in the second - working on the principle of a rotary dust collector. During operation of the apparatus, a higher pressure on the periphery of the rotating part returns a concentrated dusty flow with a low gas flow to the cyclone part. Formed by a gap, between the cyclone body and the dividing cone, a closed circuit connects the output and input of the cyclone-rotational dust collector to each other. There is a negative feedback - an effective control mechanism for such complex probabilistic systems as gas heterogeneous curvilinear flows. Negative feedback stabilizes the processes occurring in such flows. The energy of the electric motor is used in the cyclone-rotational dust collector for the movement of dusty gas, concentration, coagulation of fine dust, its return from the rotary to the cyclone zone, dispersion and capture, with the aim of saving energy and material resources. The main task of the theory of centrifugal separation of dusty flows is to find the minimum diameter of a particle that has a practically perceptible relative radial velocity. Known deterministic models of centrifugal separation are either too simple and ignore many factors that determine the process, or in attempts to account for them are too cumbersome and difficult to solve, although they are also not free from various assumptions and limitations. The stochastic model takes into account the integral set of various influences on the radial drift of the Stokes particle from the center to the periphery of the swirling flow. The paper presents the results of the study of the structure of the three-dimensional two-phase gas flow with highly dispersed inclusions in cyclonic-rotary dust collectors using 3D geometric models with the aim of visualizing these flows using computer graphics methods. Numerical studies were carried out using the k-e model of turbulence with scaled wall functions.

An approach to differentiation and evaluation of mineral resource potential in coal mining

A mining company is a complex probabilistic system which functions in-between the geological and market environments. These environments are the carriers of various uncertainties which have influence on the business success. The authors discuss the background of differentiation of the mineral resource potential in terms of a coal field as transformation of a natural possibility to the manmade reality. It is distinguished between the limit, achievable and investment potentials. This type design takes into account the stages of geological exploration, study of coal properties and actual mining of the subsoil use object. The static, ergodic and non-ergodic categories of uncertainty are discussed.

Advances in probabilistic model checking with PRISM: variable reordering, quantiles and weak deterministic Büchi automata

The popular model checker PRISM has been successfully used for the modeling and analysis of complex probabilistic systems. As one way to tackle the challenging state explosion problem, PRISM supports symbolic storage and manipulation using multi-terminal binary decision diagrams for representing the models and in the computations. However, it lacks automated heuristics for variable reordering, even though it is well known that the order of BDD variables plays a crucial role for compact representations and efficient computations. In this article, we present a collection of extensions to PRISM. First, we provide support for automatic variable reordering within the symbolic engines of PRISM and allow users to manually control the variable ordering at a fine-grained level. Second, we provide extensions in the realm of reward-bounded properties, namely symbolic computations of quantiles in Markov decision processes and, for both the explicit and symbolic engines, the approximative computation of quantiles for continuous-time Markov chains as well as support for multi-reward-bounded properties. Finally, we provide an implementation for obtaining minimal weak deterministic Büchi automata for the obligation fragment of linear temporal logic (LTL), with applications for expected accumulated reward computations with a finite horizon given by a co-safe LTL formula.

Study ways of reducing occupational exposure among machine operators in agriculture

The problem of reducing occupational risk in agriculture is extremely complex and at present not found a universal way to solve it. Reduction of occupational risk should be considered as a major component part of occupational safety as one of the most important functions of state authorities and business entities. Current trends in the growth of professional (production) risks in agriculture necessitated the development of an industry-wide system assessment and the introduction of modern methods of management of labour safety. One of the priority areas reducing the number of accidents at production is increased attention to the prevention of accidents and occupational diseases on the basis of existing production of dangerous and harmful factors, there are certain risks of injury and health loss. Modern scientific and methodological approaches and experiences of developed countries show that an effective model of protecting workers from negative (threat) impact the production environment should be based on occupational risk management. Implementation of quantitative methods for the assessment of occupational risks is one of the strategic directions achievements in the state acceptable level of safety, environmental and industrial objects. In the conditions of modern agricultural production is a complex probabilistic system, in which, as a rule, there is an unresolved danger that is inherent through participation in the process of a man with his emotional, physiological and psychological weakness, there is always the risk of an accident. In the traditional tasks of labour protection are investigating the actions of the employee as a potential source of danger because of his wrong actions, ignorance of safe methods of work. However, the technical security will play a critical role in solving problems of complex reduce the risk of injury to the mechanized processes of agriculture, that allows to consider this problem as a new and up to date.

Speeding-up structured probabilistic inference using pattern mining

In many domains where experts are the main source of knowledge, e.g., in reliability and risk management, a framework well suited for modeling, maintenance and exploitation of complex probabilistic systems is essential. In these domains, models usually define closed-world systems and result from the aggregation of multiple patterns repeated many times. Object Oriented-based Frameworks such as Probabilistic Relational Models (PRM) thus offer an effective way to represent such systems. They define patterns as classes and substitute large Bayesian networks (BN) by graphs of instances of these classes. In this framework, Structured Inference avoids many computation redundancies by exploiting class knowledge, hence reducing BN inference times by orders of magnitude. However, to keep modeling and maintenance costs low, object oriented-based framework’s classes often encode only generic situations. More complex situations, even those repeated many times, are only represented by combinations of instances. In this paper, we propose to determine online such combination patterns and exploit them as classes to speed-up Structured Inference. We prove that determining an optimal set of patterns is NP-hard. We also provide an efficient algorithm to approximate this set and show numerical experiments that highlight its practical efficiency.

Evaluating Complex MAC Protocols for Sensor Networks with APMC

In this paper we present an analysis of a MAC (Medium Access Control) protocol for wireless sensor networks. The purpose of this protocol is to manage wireless media access by constructing a Time Division Media Access (TDMA) schedule. APMC (Approximate Probabilistic Model Checker) is a tool that uses approximation-based verification techniques in order to analyse the behavior of complex probabilistic systems. Using APMC, we approximately computed the probabilities of several properties of the MAC protocol being studied, thus giving some insights about it performance.

Blocking Gibbs sampling in very large probabilistic expert systems

We introduce a methodology for performing approximate computations in very complex probabilistic systems (e.g. huge pedigrees). Our approach, called blocking Gibbs, combines exact local computations with Gibbs sampling in a way that complements the strengths of both. The methodology is illustrated on a real-world problem involving a heavily inbred pedigreee containing 20 000 individuals. We present results showing that blocking-Gibbs sampling converges much faster than plain Gibbs sampling for very complex problems.

Communications

In the construction of Beer's Predictive Model for control of operations in “complex probabilistic systems” a major exercise is the adjustment of resources to meet current productivity values so as to stabilize overall system output. There arise, however, certain theoretical problems in this adjustment exercise and this communication examines some of them.

A general simulation methodology for optical bar code evaluation

A simulation methodology ofr estimating the probability of the occurrence of a given rare event in a complex probabilistic system is presented. The practical implementation of the critical value stratification variance reduction technique is given in detail to explore the problems that arise in the generation of sample values where one usually encounters dependent continuous distributions. The methodology is set in the context of evaluating optical bar code systems and the effectiveness of alternative decoding logic schemes. The objective in these applications is to estimate the probability of various types of decoding errors (1×10—4 or smaller). The methodology presented should prove a valuable guideline for developing specific procedures when one attempts to use Monte Carlo Simulation for estimating probabilities of rare events in complex systems.

Current trends in geomathematics

Geoscience has extended its role and improved its applications by the development of geophysics since the nineteen-thirties, geochemistry since the nineteen-fifties and now, in the late nineteen-sixties, a new synergism leads to geomathematics; again the greatest pressure for change arises from areas of application of geoscience and, as the problems to which geoscience is applied increase in complexity, the analytical tools become more sophisticated, a development which is accelerated by growth in the use of computers in geological problem-solving. In the next decade the problems with greatest public impact appear to be the ones which will receive greatest emphasis and support. This will require that the geosciences comprehend exceedingly complex probabilistic systems and these, in turn, demand the use of operations research, cybernetics and systems analysis. Such a development may well lead to a change in the paradigms underlying geoscience; they will certainly include more realistic models of “real-world” systems and the tool of simulation with cybernetic models may well become the basis for rejuvenation of experimentation in the geosciences.

The Systems Approach to Education: A Practical Viewpoint

The purpose of the foregoing articles is to consider a specific approach to education: a systems approach. A school system consists basically of a collection of individuals connected together through the community. The system may be the entire school, the common room, one class, one class plus its teacher, one pupil plus one teacher, etc. The number and types of systems within a school are many, and because education deals with the brains and minds of individuals, it is dealing with the complex probabilistic system in every person and their complex probabilistic inter-relations. It is an environment in which control is apparent, and, therefore, well suited to a cybernetic study using a systems approach.