2002, VOLUME 3 #1. "TRANSPORT AND TELECOMMUNICATION". SCIENTIFIC & RESEARCH JOURNAL OF TTI, ISSN 1407-6160
Transport and Telecommunications are two global technologies that play the leading role in the world today. The creation of the unique European transport area is ensured by their development in the considerable degree. Our edition is one more afford on the way of speeding up of this process.
The aim of the journal is to acquaint the reader with the national experience of various countries in the fields of transport and telematics applied researches as well as with the working materials of the European thematic networks and the research projects in this area.
We hope that our edition will be interesting to the wide range of the researchers, academics and professionals, and we invite all interested persons to take part in the forming of its information politics.
This special edition is devoted to the International Conference "Reliability and Statistics in Transportation and Communication" (October 15, 2001, Riga, Latvia. Host organization - Transport and Telecommunication Institute). The edition includes texts of conference reports written by the authors in a special journal version.
The authors have submitted the material in the English or Russian in accordance with the official languages of the Conference. Therefore, for the convenience of readers the editorial board has divided the selected materials into two editions - English (Vol.3, N1, 2002) and Russian (Vol.3, N2, 2002).
- Title List and Editorial Board
- Editorial Notes
- Programme Of The International Conference "Reliability And Statistics In Transportation And Communication (Relstat'01)" 15 October 2001. Riga, Latvia
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We have a set of M jobs, the j-th job has duration lj and must start within the time interval [aj,bj], j=1,...,M. Every job must be performed without interruption, each machine can perform every job and only one job can be performed in a given time on a given machine. A sequential greedy-type algorithm is proposed for finding the "optimal" starting time for each job which minimizes the maximal number of machines needed to perform all jobs. This algorithm is using the entropy criterion for finding the "best" position for jobs. Algorithms with similar ideas were implemented in designing the Aeroflot Aviation scheduling .
The globalisation of markets in conditions of different cultures derivate rather complex information problems. The sciences about complexity - fractal geometry and theory of the determined chaos, - offer new tools of the analysis of open systems. By more formal consideration this new paradigm appears by generalization of existing methods of processing of the information and allows solve some problems of transport telematics. The new complex models combine fractals, chaos and non-linear methods. This new sight reduces opportunities of the control in quickly varying situations, increases uncertainty and, at the same time, offers a general picture, how the world market works.
Keywords: telematics, self-organization, information, open system, fractal, chaos
Testing models implementation at software engineering practice is analyzed. A kind of test model classification is suggested. Life-cycle oriented testing models and formal methods oriented models are discussed as well as product type oriented models. A possibility of testing automation regarding the selected model is analyzed. Practical methodologies are investigated to define a suitable testing model. Requirements for the appropriate testing model selection are formulated.
Keywords: Testing Model, Software Engineering, Requirements
Communication is one of the most important domains of air traffic control system from flight safety point of view. The most fundamental and difficult problem is providing reliability and fault tolerance of such systems. Paper investigates reliability of repairable voice communication channels (air/ground and ground/ground) of air traffic control systems with periodical sessions of communications. Three different test strategies is described:
1. Communication channel does not have built-in-test equipment.
2. Communication channel has built-in-test equipment with diagnosis procedures during communication sessions.
3. Communication channel has periodical test in the pauses between communication sessions.
Marcovian models are studded and communication channel availability is examined for each of above mentioned test strategies. Some numerical examples of real communication systems are presented.
Keywords: test, communication channel, air traffic control
Some simple statistical model for fatigue life of composite material consisting mainly of parallel rigid components (strands) is offered. The model, which can be in some way considered as extension and specification of Daniels's model for composite material, allows to get S-type curve of internal stress growth and, finally, to see the connection between static strength distribution parameters and S-N fatigue curve (Wholer curve).
Keywords: composite, strength, fatigue, fatigue curve
The problem of finding sampling distributions for truncated laws remains today perhaps the most difficult and important of all the problems of mathematical statistics that require considerable efforts and great skill for investigation. The technique discussed here is based on use of the unbiasedness equivalence principle in mathematical statistics and often provides a neat method for finding sampling distributions. It avoids explicit integration over the sample space and the attendant Jacobian but at the expense of verifying completeness of the recognized family of densities. Fortunately, general results on completeness obviate the need for this verification in many problems involving exponential families. Examples are given to illustrate that in many situations this technique allows one to find sampling distributions for truncated laws by simple way.
Keywords: Truncated law, Sampling distribution, Unbiasedness equivalence principle
Y. M. Paramonov, K. N. Nechval, V.I. Abramov & A.A. Glagovsky, Fatigue-Pron Airframe Item Inspection Modeling By The Use Of Monte Carlo Method
Keywords: Fatigue, airframe, test, maintenance, probability40
The training model is considered with combined training and knowledge level examination cycles. Elementary observation is represented by the answer to the question suggested, and the result observer is thus binary variable (correct/incorrect). At the same time demonstration (confirmation) of the correct answer serves as the elementary training step, which changes the probability of a correct answer in the future. The correct and incorrect answers can follow each other in arbitrary combination. Reasonable assumption consists in monotonic increasing of probability of the correct answer independently of the results of previous examination tests. At least we can speak on possible approximation of this probability in the family of increasing functions (increasing in the average).
The approach to the statistical estimation of the parameters of the model described is suggested. Parametric and non-parametric maximum likelihood estimates are considered. Computational aspects of the problem are discussed.
Keywords: Training models, statistical estimation, incomplete observations, lifetime
In the classical statement of the one-period inventory problem, one determines the optimum order quantity to maximize the expected profit. In this case, the variability of costs - or benefits - resulting from different inventory policies is completely ignored. In order to take into account the 'riskiness' of the inventory policies, in the literature two alternative objectives were proposed. The first objective - "maximizing expected utility" - suffers from two drawbacks: (i) the relevant risk of an investment by a value-maximizing firm cannot be appropriately measured by the total variance of the return from that investment, (ii) this criterion may imply the existence of agency problems. The second objective - "maximizing the probability of realizing a predetermined level of profit" avoids the definition of risk altogether, but it is not at all clear how a value-maximizing firm should specify the cut-off rate of profit. This paper considers the inventory problem under the new objective. This objective - "maximizing the expected profit multiplied by the probability of reaching or exceeding its value" - is commonly adopted by managers but largely ignored in the literature. To illustrate the proposed criterion, a numerical example is given.
Keywords: Inventory, Control, New objective
The suppositions on AE conformity to phases of fatigue fracture development are made at the base of АE process formation self-similarity postulate and of one of microcrack system configuration stability at the polycrystalline material. The calculations under the offered model do not contradict experimental data obtained at the aluminum alloy.
Keywords: fatigue, material, crack, acoustic emission
Helen Afanasyeva, The Resampling-Estimator Of The Queuing Length Non-Stationary Distribution For The Queuing System
Keywords: Queuing system, Queuing length, Resampling, Estimation.
In this paper, we present an approach to invariant confidence intervals that emphasizes pivotal quantities. We consider confidence interval problems that are invariant under a group of transformation G such that the induced group acts transitively on the parameter space. The purpose of this paper is to give a technique for deriving confidence intervals with a minimum length property. Examples illustrating the use of this technique are given.
Keywords: Confidence interval, Shortest length, Technique for constructing
Keywords: Electrodynamic screen, ferrite antenna, interference protection
New method for design of high selective narrow-band lowpass digital filters (LPFs) with linear phase is described. This technique presents possibility of special class synthesis of arbitrary order Finite Impulse Response (FIR) filters implemented without multiplications. This improvement means high computational efficiency and increase of the computation speed. Synthesized filters have unified structure components and any order filters provide wide dynamic range of processing data.
Keywords: digital signal processing, fast filtering
This paper illustrates application of Hierarchical Resampling method for simulation of hierarchical sequential-parallel reliability systems in the case when the same sample population for some elements is used. Modifications of Hierarchical Resampling method are proposed for given task. Formulas for variance of estimators are given. Obtained estimators are compared with traditional ones calculated using empirical distribution functions. It is shown that considered approach can be a good alternative to traditional one.