The first step towards condition based maintenance of the milling plant is the implementation of online condition monitoring of the mill. The following paper presents and analyses methods of monitoring the key performance factors of a vertical spindle mill that is suited for implementation on older power stations, i.e. the quantity (mass flow rate) and quality (particle fineness) of the pulverised fuel produced by the mill. It is shown herein that the mill throughput can be monitored on-line using a simple mill energy balance that successfully predicts the coal throughput within 2.33% as compared to a calibrated coal feeder. A sensitivity analysis reveals that the coal moisture is a critical measurement for this method to be adopted as an on-line mass flow monitoring tool. A laser based particle size analyser tool was tested for use in the power plant environment as an online monitoring solution to measure pulverised fuel fineness. It was revealed that several factors around the set-up and operation of the instrument have an influence on the perceived results. Although the instrument showed good precision and repeatability of results, these factors must be taken into account in order to improve the accuracy of the reported results before the instrument can be commissioned as an on-line monitoring solution.

The formulation of a plate finite element with so called ‘physical’ shape functions is revisited. The derivation of the ‘physical’ shape functions is based on Hencky-Bollé theory of moderately thick plates. The considered finite element was assessed in the past, and the tests showed that the solution convergence was achieved in a wide range of thickness to in-plane dimensions ratios. In this paper a holistic correctness assessment is presented, which covers three criteria: the ellipticity, the consistency and the inf-sup conditions. Fulfilment of these criteria assures the existence of a unique solution, and a stable and optimal convergence to the correct solution. The algorithms of the numerical tests for each test case are presented and the tests are performed for the considered formulation. In result it is concluded that the finite element formulation passes every test and therefore is a good choice for modeling plate structural elements regardless of their thickness.

Investigations showing the possibility of BTX biodegradation present in the water environment under anoxic conditions have been presented. The effects of transformation of benzene, toluene, o-xylene and p-xylene by indigenous to sewage microorganisms as well as by isolated species of bacteria like Aeromonas sobria, Enterobacter sakazaki, Pseudomonas aeruqinosa, Staphylococcus lentus and the mixture of these species varied distinctively. The results and calculated degradation rates have been compared to some results given by other authors. In anoxic conditions all investigated aromates have shown to be biodegradable. The highest rate of degradation was found for isolated species of bacteria from municipal sewage.

The paper presents a method of how the nonlinear boundary condition [1] may be applied in nonlinear problems of electromagnetic field theory. It is introduced for problems with nonlinear conductivity. An analytical procedure has been constructed, which seeks to reduce calculations related with the nonlinear region. In order to verify the proposed solutions, two problems have been formulated: one of linear and the other of cylindrical symmetry. These have been additionally solved by the authors’ modification of the perturbation method that has been described in previous papers [7, 8, 10]. The electromagnetic field distribution obtained thereby has served as a referential result since it can obtain very accurate solutions [10]. Relative errors of electric and magnetic field strength are introduced to verify the results.

During heat transport through the walls of a hollow sphere, the heat stream can achieve extreme values. The same processes occur in regular polyhedrons. We can calculate the maximum heat transfer rate, the so-called critical heat transfer rate. We must assume here identical conditions of heat exchange on all internal and external walls of a regular polyhedron. The transfer rate of heat penetrating through the regular polyhedron with different heat transfer coefficients on the walls is called the heat transfer rate with asymmetric boundary conditions. We show that the heat transfer rate in this case will grow up if we replace those coefficients with their average values.

A series of Al-5Ti-1B master alloys were obtained via fluoride salt process by holding them between 780°C and 880°C for 10-90 min. The influence of holding temperature and time during preparation on the microstructure and its refining performance were investigated by X-ray diffractometer, optical microscopy and scanning electron microscopy equ ipped with energy dispersive X-ray spectroscopy. The results indicated both the morphology and the distribution of TiB2 and Al3Ti were seriously affected by holding conditions. Inadequate TiB2 particles were generated when holding time was short. However, Fe-containing impurity particles that aggregated along the matrix grain boundaries were found after the prolonged holding time. The refining and microhardness test results revealed that Al -5Ti-1B, the one held at 820°C for 30 min showed the optimum refining efficiency on Al-Cu alloy.

Air core solenoids, possibly single layer and with significant spacing between turns, are often used to ensure low stray capacitance, as they are used as part of many sensors and instruments. The problem of the correct estimation of the stray capacitance is relevant both during design and to validate measurement results; the expected value is so low to be influenced by any stray capacitance of the external measurement instrument. A simplified method is proposed that does not perturb the stray capacitance of the solenoid under test; the method is based on resonance with an external capacitor and on the use of a linear regression technique.

Wind turbines are nowadays one of the most promising energy sources. Every year, the amount of energy produced from the wind grows steadily. Investors demand turbine manufacturers to produce bigger, more efficient and robust units. These requirements resulted in fast development of condition-monitoring methods. However, significant sizes and varying operational conditions can make diagnostics of the wind turbines very challenging.

The paper shows the case study of a wind turbine that had suffered a serious rolling element bearing (REB) fault. The authors compare several methods for early detection of symptoms of the failure. The paper compares standard methods based on spectral analysis and a number of novel methods based on narrowband envelope analysis, kurtosis and cyclostationarity approach.

The very important problem of proper configuration of the methods is addressed as well. It is well known that every method requires setting of several parameters. In the industrial practice, configuration should be as standard and simple as possible. The paper discusses configuration parameters of investigated methods and their sensitivity to configuration uncertainties

The solution of planetary gear with simplifying technology using the same geometry of the sun gear and the central gear is already known. The authors decided to change this concept i.e. to design a planetary gear with the same geometry of satellite wheels, which cooperate with a sun gear and a central gear with different number of teeth. The structural solution of elements of the gear is analyzed taking advantage of computational technique. Geometrical dimensions are described for the sake of teeth correction. Calculations and structural solutions of this kind of transmission are shown in the article.

The condition number of the Generalized Inertia Matrix (GIM) of a serial chain can be used to measure its ill-conditioning. However, computation of the condition number is computationally very expensive. Therefore, this paper investigates alternative means to estimate the condition number, in particular, for a very long serial-chain. For this, the diagonal elements of the GIM are examined. It is found that the ratio of the largest and smallest diagonal elements of the GIM, when scaled using an initial estimate of the condition number, closely resembles the condition number. This significantly simplifies the process of detecting ill-conditioning of the GIM, which may help to decide on stability of the system at hand.

The support for the stable functioning of business entities with focus on their further development is impossible without an effective system of financial security, because any time there is a danger of implementing a variety of risks that can lead to the onset of the crisis. It should be noted that the implementation of measures to ensure financial security is most effective when they are applied long before the crisis - it makes business entities able to recognize early trends of crises and have time for preparedness. In the case when it comes to the global economic crisis, which cannot be prevented, timely measures to ensure financial security can minimize its negative effects, and if the crisis is expected at the level of the enterprise, it will be able to avoid it altogether. The study clarified the theoretical basis of ensuring the business entity financial security - namely, the definition of "financial security" and a list of its tasks, functions and principles. The existing problem of providing financial security are researched. A qualitative and quantitative methods for assessing the financial condition of a business entity are showed. The research has established that the main problems of ensuring the financial security of business entity need to be addressed at the state level, but the early assessment of external and internal environment of economic units significantly reduces the risk of certain threats and thus increases financial security of business entities. The showed methods of assessing the financial situation can be used in practice of national business entities.

Multidisciplinary research was carried on in 1978/79 in the region of Admiralty Bay and Arctowski Station. This area is representative of the near-shore Antarctic ecosystem. It is characterized by a number of local traits such as climate, ice conditions, hydrology, hydrochemistry and hydrodynamics. Estimates were made of primary production and abundance of zooplankton in Admiralty Bay and of the biomass and quantity of food taken by avi-fauna and pinnipeds. Main routes and directions of transport of mineral and organic matter are shown; some of them have been estimated quantitatively. A continuous inflow of organic matter from Bransfield Strait is necessary for the summer functionning of Admiralty Bay.

In the summers of 1978 and 1979 meteorological observations and measurements were carried out in South Spitsbergen. These investigations gave a characteristic of the summer meteorological conditions in the forefield of the Gås Glacier. Some regularities were found to exist in the distribution of air temperature and other meteorological elements.

Temporal differentiation of the air thermal conditions in SW part of Spitsbergen has been presented in this paper. Daily meteorological records of the Polish Polar Station of the Polish Academy of Sciences in Hornsund have been used for the period of 1978—1986. Distributions of basic thermal indices based on mean, maximum, minimum air temperatures and minimum temperature at a ground surface have been given. Annual patterns of the above elements of various occurrence probabilities have been also presented and thermal periods have been distinguished.

The aim of this article is to defi ning problems occurring in the spatial management system, including those independent of subsequent legislative changes. The process of adopting decisions to be viable and socially equitable and execute the requirements of spatial order and sunstainable development requires fundamental changes. The study draws a conclusion – important in the context of subsequent research activities – that the varied application of development decisions in diff erent municipalities is also the result of not preparing a large part of the representatives of municipalities for specifi c spatial activities.

Small construction objects are often built by standard task teams. The problem is, how to allocate these teams to individual works? To solve the problem of allocation three methods have been developed. The first method allows to designate optimal allocation of teams to the individual works in deterministic conditions of implementation. As a criterion of the optimal allocation can be applied: “the minimization of time” or “the minimization of costs” of works execution. The second method has been developed analogously for both criteria but for stochastic conditions and for the stochastic data. The third method allows to appoint a compromise allocation of teams. In this case, the criteria “the minimization of time” and “the minimization of costs” are considered simultaneously. The method can be applied in deterministic or stochastic conditions of works implementation. The solutions of the allocation problems which have been described allow to designate the optimal allocation of task teams and to determine the schedule and cost of works execution.

Thermal imagers often work in extreme conditions but are typically tested under laboratory conditions. This paper presents the concept, design rules, experimental verification, and example applications of a new system able to carry out measurements of performance parameters of thermal imagers working under precisely simulated real working conditions. High accuracy of simulation has been achieved by enabling regulation of two critical parameters that define working conditions of thermal imagers: imager ambient temperature and background temperature of target of interest. The use of the new test system in the evaluation process of surveillance thermal imagers can bring about a revolution in thermal imaging metrology by allowing thermal imagers to be evaluated under simulated, real working conditions.

Managing human consumption has a major impact on the functioning of societies, and – even more importantly – on the condition of our planet. What does the future hold?

The advance of technical state criteria for elements of mining hoists demands a basic strength-fatigue analysis where the real values of loads and the real time function of the load variability could be used. That problem concerns also the suspension gear of skip and balance ropes, where fatigue durability should be considered as time function related to the hoist facility type. Such objective can not be achieved without comprehensive study of the dynamics of processes both in the regular operation of the facility and in its emergency states. In this work the author presents some considerations, that are however, limited to the analysis of dynamic phenomena observed in the condition of the emergency braking of the hoist facility. The results were verified by load measurements taken for some elements of the analysed real object system.

This study gives an analysis of the variation of main meteorological parameters on the Station Arctowski in the time from December 1979 through March 1980 — the summer season of the IV Antarctic Expedition of the Polish Academy of Sciences. Characteristics of wind speed and direction, of air temperature, atmospheric pressure, precipitation, cloudiness, soil temperature at the station and surface water temperatures of the Admiralty Bay are based on the standard synoptic observations.

Ground temperature measurement results in main ecotopes of the Kaffiöyra coastal plain (Oscar II Land, northwestern Spitsbergen): sea beach, tundra and morainic plateau, are presented and discussed in the paper. The spatial distribution of thermal conditions is discussed with particular regard to temperature of the active surface and vertical gradients of temperature dependent on daytime and weather conditions.

Transformers are one of the most important components of the power system. It is important to maintain and assess the condition. Transformer lifetime depends on the life of its insulation and insulation life is also strongly influenced by moisture in the insulation. Due to importance of this issue, in this paper a new method is introduced for determining the moisture content of the transformer insulation system using dielectric response analysis in the frequency domain based on artificial bee colony algorithm. First, the master curve of dielectric response is modeled. Then, using proposed method the master curve and the measured dielectric response curves are compared. By analyzing the results of the comparison, the moisture content of paper insulation, electrical conductivity of the insulating oil and dielectric model dimensions are determined. Finally, the proposed method is applied to several practical samples to demonstrate its capabilities compared with the well-known conventional method.

The detection of transformer winding deformation caused by short-circuit current is of great significance to the realization of condition based maintenance. Considering the influence of environment and measurement errors, an online deformation detection method is proposed based on the analysis of leakage inductance changes. First, the operation expressions are derived on the basis of the equivalent circuit and the leakage inductance parameters are identified by the partial least squares regression algorithm. Second, the amount of the leakage inductance samples in a detection time window is determined using the Monte Carlo simulation thought, and then the samples in the confidence interval are obtained. Last, a criteria is built by the mean value changes of the leakage inductance samples and the winding deformation is detected. The online detection method considers the random fluctuation characteristics of the leakage inductance samples, adjust the threshold value automatically, and can quantify the change range to assess the severity. Based on the field data, the distribution of the leakage inductance samples is analyzed to obey the normal function approximately. Three deformation experiments are done by different sub-winding connections and the detection results verify the effectiveness of the proposed method.