Dynamics of the Rolling Stock and the Choice of Parameters of Vibration Dampers

Modern railway rolling stock should meet requirements regarding comfort (maximum travel speed with minimum vibrations of wagons, noiselessness of movement, etc.).To eliminate the influence of dynamic loads, rolling stock is equipped with vibration dampers. The objective of the work is to select the parameters of the vibration dampers of rolling stock, depending on its characteristics, to ensure the due indicators of comfort and safety of transportation of passengers and goods by rail. To achieve this objective, applied methods of mathematical modelling were based on numerical programming of operation of dynamic systems. The indicators of vibration dampers are evaluated according to the results of studies of the dynamics of the rolling stock (in particular, of vibration protection rates).Assessment of dynamic state of the rolling stock implies application of methods of mathematical and physical modelling, which include the development of a physical and mathematical model, a calculation algorithm, and computer programming. The study of the mathematical model by numerical methods makes it possible to carry out a multifactorial experiment using a large number of input parameters (factors) and to select the characteristics of vibration dampers that are optimal for the conditions under consideration.To solve dynamic problems, the harmonic perturbation model, which is the most widespread, was specified in the form of a sinusoid with a period corresponding to the rail length.A quantitative assessment of the vibration process (frequency, amplitude) makes it possible to identify the main processes occurring in the system under consideration under various types of external load. The introduced assumptions related to rigidity, mobility and geometric immutability of the system allow determining the methods for obtaining a mathematical model and considering the vibrations as flat ones.The equations were solved in MathCad Prime 4.0 package using the Runge–Kutta method with automatic step selection. The subsequent study of the properties of the dynamic system was carried out by changing the resistance parameter of dampers of the first stage of spring suspension, while recording the values of the amplitude of the vibrations of the system and the period.The analysis of the results has shown that the vibration period of the body and bogies under any changes in the resistance parameter of the damper remains unchanged, while rational parameters of resistance of axle box dampers have been revealed for specified indicators. Hydraulic vibration dampers with the revealed parameters used on rolling stock help to reduce wear and damageability of running gears, improve ride comfort and traffic safety, as well as to reduce repair and maintenance costs.

A Novel Dynamic Approach to Cost-Optimal Energy Performance Calculations of a Solar Hot Water System in an nZEB Multi-Apartment Building

This paper presents the methodology for conducting a cost-optimal energy performance calculation of a solar hot water system, used for space heating and domestic hot water needs. The calculation is based on dynamic hourly methods, according to the new Energy Performance of Buildings’ (EPB) set of standards EN 15316:2017, and a revision of the standard EN 15316-5:2017 from the year 2021, dealing with storage-tank water temperature calculations. The paper provides proposals for modifications to these newly introduced standards, in order to overcome the observed ambiguities and shortcomings. The calculation of annual energy performance of a building was performed on an hourly basis over a year for the reference of an nZEB multi-apartment building, for a climate area of the city of Zagreb, taking into account water temperature change in the layers of the storage tank connected to solar collectors and hot water boilers. The cost-optimal solution was then determined by varying individual parameters of the building technical system. The influence of these parameters on the energy efficiency of the building was analyzed in detail. Furthermore, the results were compared against those obtained by the Croatian calculation algorithm based on the previous set of EPB standards, EN 15316:2008, currently used EU-wide for the energy performance certification of buildings. The results indicated that the calculation methods of the present algorithm underestimated the consumption of building primary energy by 12%. The energy delivered by solar collectors was underestimated by 18%.

Additional opportunities for using computer technologies in expert analysis of laboratory data

The presented work reflects the author’s algorithm of mathematical processing and possible interpretations of the results obtained when creating expert analytical systems using computer technology. As initial parameters for the construction of neural networks of the second level, it is proposed to use individual results of calculations of the ratios of a number of laboratory indicators capable of forming a single functional cluster (leukogram, indicators of water-electrolyte balance, protein fractions, etc.). Further, using the proposed calculation algorithm and the archive database, structural features in the ′deformation′ of the ratio panel were compared against the background of the growth of each indicator, a matrix table was built reflecting the degree (correlation coefficients, KCr) of the coincidence of the features of the formation of the structure of the obtained panels of the parameters determined in individual observations. At high values of KCr, a conclusion is made about their (determined parameters) unified participation in the mechanism of emerging disorders. Thus, the system allows you to establish a leading complex of associated relationships by changes in the structure of ratios in the selected panel, corresponding to the dynamics of deviation of the target (analyzed) indicator, thereby differentiating the different mechanisms of formation of pathological deviations in this patient, the manifestation and balance of their values in the system-wide response, to evaluate the specific value of the absolute indicator as the final result of such interaction at the time of examination of the patient. The approach used, proposed by the authors, allows us to evaluate not only quantitative relationships, but also the features of the manifestation of the functional properties of the evaluated indicators. All of the above significantly expands the informativeness of the obtained laboratory data, allowing us to build a reasonable paradigm of the connections of the emerging complex of pathological disorders in each individual case. In the list of references, the authors cite publications as concrete examples of the use of the proposed approach in assessing a complex of disorders with different pathological processes using different panels in calculations.

Algorithm of the calculation of technological for several objects of technological standardization

Цель исследования – разработка алгоритма расчета технологических показателей отдельно по видам выпускаемой продукции для интегрированного целлюлозно-бумажного комбината при сбросе сточных вод после очистки сточных вод на единых очистных сооружениях промышленных стоков. Использован балансовый метод расчёта значений масс загрязняющих веществ, образующихся на тонну выпускаемой продукции ЦБК на основе масс загрязняющих веществ, образующихся во вспомогательных технологических процессах, с учетом очистки сточных вод на общепроизводственных очистных сооружениях. Технологические показатели установлены отдельно для продукции, нормируемой по беленой или небеленой целлюлозе. Если фактические значения технологических показателей превысят значения технологических показателей НДТ, то необходимо разработать водоохранные мероприятия по достижению этих показателей и, до момента их достижения, оплачивать негативное воздействие на водные объекты со стократным повышающим коэффициентом. Разработан алгоритм и функциональные зависимости расчета технологических показателей для ЦБК, выпускающих продукцию, содержащую в композиции беленую и небеленую целлюлозу. Алгоритм рассмотрен на примере условного ЦБК, выпускающего первичные небелёные и беленые волокнистые полуфабрикаты и продукцию полного цикла. К первичным волокнистым полуфабрикатам небеленым отнесены: хвойная и лиственная целлюлоза, ТММ, ХТММ; к первичным волокнистым беленым полуфабрикатам отнесены: беленая хвойная и лиственная целлюлоза, БХТММ; к продукции полного цикла отнесены бумага, картон и продукция их переработки. Алгоритм расчета состоит из пяти этапов: 1 – построение балансовой схемы расчета технологических показателей; 2 – расчет технологических показателей для первичных волокнистых полуфабрикатов небеленых; 3 – расчет технологических показателей для первичных волокнистых полуфабрикатов беленых; 4 – расчет технологических показателей для продукции полного цикла; 5 – расчет значений технологических показателей для каждого вида продукции с учетом очистки на общепроизводственных очистных сооружениях. The purpose of the study is to develop an algorithm for calculating technological indicators separately by types of products for an integrated pulp and paper mill when discharging wastewater after wastewater treatment at unified industrial wastewater treatment plants. A balance method was used for calculating the values of the masses of pollutants formed per ton of output from the pulp and paper mill based on the masses of pollutants formed in auxiliary technological processes, taking into account wastewater treatment at general industrial treatment facilities. Technological indicators are set separately for products rated for bleached or unbleached pulp. If the actual values of technological indicators exceed the values of technological indicators BAT, then it is necessary to develop water protection measures to achieve these indicators and, until they are reached, to pay for the negative impact on water bodies with a hundredfold increasing coefficient. An algorithm and functional dependencies for calculating technological indicators for pulp and paper mills producing products containing bleached and unbleached cellulose in the composition have been developed. The algorithm is considered on the example of a conventional pulp and paper mill, which produces primary unbleached and bleached fibrous semi-finished products, and full-cycle products. Primary unbleached fibrous semi-finished products include: coniferous and deciduous cellulose, ТМP, CТМP; primary fibrous bleached semi-finished products include: bleached softwood and hardwood pulp, BCTMP; full cycle products include: paper, cardboard and their processing products. The calculation algorithm consists of five stages: 1 – building a balance sheet for calculating technological indicators; 2 – calculation of technological indicators for primary fibrous semi-finished products, unbleached; 3 – calculation of technological indicators for primary fibrous semi-finished products bleached; 4 – calculation of technological indicators for full cycle products; 5 – calculation of the values of technological indicators for each type of product, taking into account cleaning at general production treatment facilities.

Development of a Procedure for the Determination of the Buckling Resistance of Steel Spherical Shells According to EC 1993-1-6

This paper presents the process of developing a new procedure for estimating the buckling capacity of spherical shells. This procedure is based entirely on the assumptions included in the standard mentioned, EN-1993-1-6 and also becomes a complement of EDR5th by unifying provisions included in them. This procedure is characterized by clarity and its algorithm is characterized by a low degree of complexity. While developing the procedure, no attempt was made to change the main postulates accompanying the dimensions of the spherical shells. The result is a simple engineering approach to the difficult problem of determining the buckling capacity of a spherical shell. In spite of the simple calculation algorithm for estimating the buckling capacity of spherical shells, the results obtained reflect extremely accurately the behavior of real spherical shells, regardless of their geometry and the material used to manufacture them.

Increasing the Prediction Power of Moodle Machine Learning Models with Self-defined Indicators

Starting with version 3.4 of Moodle, it has been possible to build educational ML models using predefined indicators in the Analytics API. These models can be used primarily to identify students at risk of failure. Our research shows that the goodness and predictability of models built using predefined core indicators in the API lags far behind the generally acceptable level. Moodle is an open-source system, which on the one hand allows the analysis of algorithms, and on the oth-er hand its modification and further development. Utilizing the openness of the system, we examined the calculation algorithm of the core indicators, and then, based on the experience, we built new models with our own indicators. Our re-sults show that the goodness of models built on a given course can be significant-ly improved. In the article, we discuss the development process in detail and pre-sent the results achieved.

Analysis of the stability of the computational algorithm to a change in the geometric parameters of cylindrical shell structures

This study deals with testing sustainability of a computational algorithm to a change in geometric parameters of cylindrical shell structures. A change in geometry implies the replacement of one type of a cylindrical shell (elliptic, hyperbolic, parabolic) with another so that the quantitative change (the difference in elevations) in the area under consideration is minimal. On the one hand, this test allows to assessing the correctness of the algorithm itself and is relevant for algorithms that use both numerical methods and symbolic calculations. On the other hand, it allows to evaluating the possibility of simplifying calculations by approximating a complex surface with a simpler one both in understanding the surface definition itself and in expressing its basic characteristics such as Lame coefficients and main curvatures. A mathematical model of deformations of shell structures based on the hypotheses of Timoshenko (Mindlin - Reisner) are used in the work. The model takes into account transverse shifts, geometric nonlinearity and orthotropy of the material, and its written in the form of a functional of the total potential strain energy. The calculation algorithm is built on the basis of the Ritz method to reduce the variational problem of the minimum functional to the solution of a system of nonlinear algebraic equations, and on the method of continuing the solution with the best parameter for its solution. All calculations were carried out in dimensionless parameters. Three types of cylindrical panels are calculated, and critical loads of buckling and deflection fields at subcritical and supercritical moments are obtained. It is shown that for the considered class of problems the previously proposed mathematical model and computational algorithm are resistant to changes in the geometry of the structure.

Infrared Image Super-Resolution via Progressive Compact Distillation Network

Deep convolutional neural networks are capable of achieving remarkable performance in single-image super-resolution (SISR). However, due to the weak availability of infrared images, heavy network architectures for insufficient infrared images are confronted by excessive parameters and computational complexity. To address these issues, we propose a lightweight progressive compact distillation network (PCDN) with a transfer learning strategy to achieve infrared image super-resolution reconstruction with a few samples. We design a progressive feature residual distillation (PFDB) block to efficiently refine hierarchical features, and parallel dilation convolutions are utilized to expand PFDB’s receptive field, thereby maximizing the characterization power of marginal features and minimizing the network parameters. Moreover, the bil-global connection mechanism and the difference calculation algorithm between two adjacent PFDBs are proposed to accelerate the network convergence and extract the high-frequency information, respectively. Furthermore, we introduce transfer learning to fine-tune network weights with few-shot infrared images to obtain infrared image mapping information. Experimental results suggest the effectiveness and superiority of the proposed framework with low computational load in infrared image super-resolution. Notably, our PCDN outperforms existing methods on two public datasets for both ×2 and ×4 with parameters less than 240 k, proving its efficient and excellent reconstruction performance.

Relationship between Visibility, Air Pollution Index and Annual Mortality Rate in Association with the Occurrence of Rainfall—A Probabilistic Approach

An innovative method was proposed to facilitate the analyses of meteorological conditions and selected air pollution indices’ influence on visibility, air quality index and mortality. The constructed calculation algorithm is dedicated to simulating the visibility in a single episode, first of all. It was derived after applying logistic regression methodology. It should be stressed that eight visibility thresholds (Vis) were adopted in order to build proper classification models with a number of relevant advantages. At first, there exists the possibility to analyze the impact of independent variables on visibility with the consideration of its’ real variability. Secondly, through the application of the Monte Carlo method and the assumed classification algorithms, it was made possible to model the number of days during a precipitation and no-precipitation periods in a yearly cycle, on which the visibility ranged practically: Vis < 8; Vis = 8–12 km, Vis = 12–16 km, Vis = 16–20 km, Vis = 20–24 km, Vis = 24–28 km, Vis = 28–32 km, Vis > 32 km. The derived algorithm proved a particular role of precipitation and no-precipitation periods in shaping the air visibility phenomena. Higher visibility values and a lower number of days with increased visibility were found for the precipitation period contrary to no-precipitation one. The air quality index was lower for precipitation days, and moreover, strong, non-linear relationships were found between mortality and visibility, considering precipitation and seasonality effects.