Research on vibroacoustic phenomena of tram vehicles for the changeable dynamics conditions

The article addresses the methodology and the results of studies of vibroacoustic phenomena generated by tram vehicles. While a tram was running at various speeds, both the noise level and surface vibrations were recorded simultaneously. These quantities determine the overall impact of tram cars on their environment. The research assumptions made enable assessment of accretion of these effects in the function of running speed, which may prove particularly for the sake recommendations as to the permissible speed of trams in urban conditions

Psychomotor performance of Polish Air Force cadets after 36 hours of survival training

Introduction The preparation of Polish Air Force cadets for survival in isolation is a necessary element of their training, to demonstrate just how difficult can be the conditions they could encounter in a combat situation. Objective. The aim of the research was to assess the effect of long-term survival training on selected coordination motor skills in Air Force cadets. Material and Methods Fifteen air force cadets aged 19.6±0.3 years exercised for 36 hours during survival training without the possibility to sleep. They were examined 4 times: Day 1 – before effort (training), Day 2 – after 24 hours training, Day 3 – directly after 36 hours training, Day 4 – next day, after an all night rest. They were examined for shooting and reaction time, the ability to maintain body balance, running motor adjustment, handgrip force differentiation, and on Days 1 and 3, exercise capacity was evaluated with a 1 mile walking test. Results The survival training resulted in significant decreases in maximum handgrip strength, corrected 50% max handgrip, maintenance of body balance and heart rate. No changes occurred in reaction time, running motor adjustment and shooting performance. Overnight rest did not result in recovery of any of the examined factors to the values observed on Day 1. Conclusions Survival training combined with sleep deprivation mostly affected peripheral factors depending on strong action from both muscles and nervous system, whereas complex tasks involving short-term central alertness and moderate exertion were maintained. In order to improve performance, more endurance strength training, if possible combined with sleep deprivation, should be introduced in military training

Tyre pyrolytic oil fuel blends in a modern compression ignition engine : A comprehensive combustion and emissions analysis

There is abundant worldwide research into combustion engine applications for tyre pyrolysis oil (TPO). However, most studies are methodologically outdated in terms of their assumed technology, either with regard to TPO production or engine application, or in their analytical approaches. The variety of radically different studies produce conflicting or ambiguous results, rendering TPÓs role as a feasible future fuel uncertain. This study is the first to provide state-of-the art combustion analysis results for thoroughly-evaluated TPO fraction optimised in a modern, industry-grade pyrolytic reactor. The fuel blends are selected for engine tests, taking into account the overall availability/compatibility of their TPO fractions with diesel. Testing with a modern, sophisticated single-cylinder research engine provides detailed analysis of combustion and both regulated and unregulated emissions. Emissions results are supported by FTIR analysis of exhaust gases, including identification of 23 species. The results show that contemporary Tier 4-compliant combustion systems with multi-pulse injection can handle high TPO-content fuels without needing re-calibration. With diesel/TPO blends of up to 40% TPO admixture, combustion phasing is substantially delayed (by 3CAD) only at near-idle loads and particularly when using heavy exhaust gas recirculation. The consequential differences in performance and emissions diminish over the test cycle. Current US EPA Tier 4 emission limits are not particularly challenging for TPO, even at 40% blending rate, but its elevated levels of particulate matter (25% increase over test cycle versus diesel baseline), sulphur oxides, aromatics and formic acid present health concerns and potential maintenance issues. These should be considered when assessing the fueĺs life-cycle environmental impact. The increase in emissions of those species correlates directly with fuel sulphur content (0.5% for neat TPO fraction), polyaromatic hydrocarbons fraction (0.49%) and acidity. Further optimisation of TPÓs composition in the reactor and via improved fuel post-processing can address these issues.© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed

An experimental assessment on a diesel engine powered by blends of waste-plastic-derived pyrolysis oil with diesel

The utilization of plastic solid wastes for sustainable energy production is a crucial aspect of the circular economy. This study focuses on pyrolysis as an effective method to convert this feedstock into renewable drop-in fuel. To achieve this, it is essential to have a comprehensive understanding of feedstock composition, pyrolysis process parameters, and the physicochemical characteristics of the resulting fuel, all correlated with engine combustion parameters. Considering this full value chain, this study provides the first unbiased and up-to-date benchmark of polypropylene and polystyrene pyrolysis oils (PPO and PSO) produced in an industrial-grade batch reactor. The pyrolysis process was optimized to achieve ultra-high liquid yield levels of 92% for PPO and 98% for PSO with minimum energy consumption. After post-processing, blending with diesel, and normative fuel analytics, combustion/emission tests involving 20 species preceded under fully controllable conditions using a state-of-the-art single-cylinder research engine. The fuel analysis results revealed significant disparities between the properties of PPO and PSO. PPO exhibited a diverse carbon structure, resulting in very low density and high volatility. On the other hand, PSO was predominantly composed of aromatics, leading to low viscosity and poor auto-ignition properties. Engine tests showed that PPO blends exhibited combustion characteristics similar to diesel, while PSO blends exhibited significant differences, particularly during the premixed combustion stage attributed to pilot injection. Following the combustion response, the addition of PPO had minimal impact on emissions, while PSO acted as an emission enhancer, resulting in over twofold increase in particulate matter at high loads. Consequently, PSO showed elevated carbon monoxide and hydrocarbon emissions due to the higher contribution of aromatics. Ultimately, this study challenges the prevailing perception of plastic-derived fuels as “dirty”. By implementing feedstock segregation to minimize polystyrene content, it is possible to achieve a fossil substitute level of 40% while meeting all emission and safety regulations for diesel engines with a minimum economic burden.© 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/bync/4.0/).fi=vertaisarvioitu|en=peerReviewed

Ternary fuel mixture of diesel, rapeseed oil and tyre pyrolytic oil suitable for modern CRDI engines

The focus on seeking alternative fuels for combustion engines has been on the environmental and political scene for many years. Simultaneously there is a more and more serious problem of non-degradable waste utilization. In the present work an attempt has been made to asses both of those aspects by proposing a tailor-made, 3-component mixture consisting of mineral diesel, crude rapeseed oil and waste tyre pyrolytic oil. It was proven that the addition of pyrolytic oil can improve some basic drawbacks of rapeseed oil / diesel mixtures like high density and viscosity or low cold filter plugging point. On the basis of maximum bio-component share and optimum physicochemical properties a best fuel sample (40% mineral diesel oil, 55% rapeseed oil and 5% pyrolytic oil fraction) had been selected for engine tests, performed on a light-duty multi-cylinder Compression Ignition (CI) engine with electronic, Common Rail (CR) injection system. The steady state tests were performed for two rotational speeds and two injection strategies (single and sequential fuel injection), for each of which a full load sweep was performed. The engine research included in-cylinder pressure analysis along with efficiency estimation and exhaust gas emission measurements. The research confirmed the assumption that the selected fuel mixture is suitable for modern CI engines. The specific fuel consumption was similar or lower for the tested fuel compared to standard diesel, except the cases were sequential injection was incorporated. Emissions remained on similar levels as for both fuels except Total HydroCarbons (THC) at sequential injection operation points, which correlated with lower fuel conversion efficiency

Influence of aerobic training on neurohormonal and hemodynamic responses to head-up tilt test and on autonomic nervous activity at rest and after exercise in patients after bypass surgery

Background: Little is known about the influence of aerobic training on the neurohormonal and hemodynamic responses to head-up tilt (HUT) and on autonomic balance at rest and after exercise in optimally treated, low risk post-coronary artery bypass grafting (CABG) patients. Methods: One hundred male patients, mean age 56 ± 6 years, 3 months after CABG, were randomized to either 6-week training on cycloergometer, 3 times a week, at 70–80% of max tolerated heart rate (HR) (training group, n = 50) or to a control group (n = 50). At baseline and at the end of the study, all patients underwent: (1) cardiopulmonary exercise test with HR recovery (HRR) assessment; (2) 60% HUT during which HR, blood pressure (BP), stroke volume (SV by impedance cardiography) were monitored and blood samples were taken for determination of plasma catecholamines and ANP levels, and plasma renin activity; (3) assessment of HR variability (HRV) in the time and frequency domains at rest. Results: During the final tests, HUT-induced changes in HR, BP, SV, cardiac output, total peripheral resistance, and noradrenaline were significantly lower in training group than in controls. In addition, after training faster post-exercise HRR, increased SDNN and a tendency towards an increase in the high frequency HRV power spectrum were found. Conclusions: Aerobic training improved neurohormonal and hemodynamic responses to head-up tilt test and favorably modified sympatho-vagal balance in low risk post-CABG patients

Validation Process for Computational Model of Full-Scale Segment for Design of Composite Footbridge

Experimental tests and numerical simulations of a full-scale segment of a foot and cycle bridge made of polimer composites are presented in the paper. The analysed structure is made of sandwich panels, which consist of glass fibre reinforced polymer (GFRP) multi-layered laminate faces and a PET foam (obtained from recycling) core. The dimensions of the segment cross-section are the same as for the target footbridge; however, span length was reduced to 3 m. The experimental tests were conducted in a laboratory of the Faculty of Ocean Engineering and Ship Technology at Gdansk University of Technology. A single vertical force was generated by a hydraulic cylinder and was applied to the platform of the structure. The experimental tests were supported by numerical analyses performed in Femap with NX Nastran software by means of the finite element method (FEM). Results obtained in the computational model were compared with results from experiments. Thus, the numerical model was validated and the obtained conclusions were used in the next step of the design process of a composite footbridge with a span length of 14.5 m

Selected Problems of Sensitivity and Reliability of a Jack-Up Platform

The paper deals with sensitivity and reliability applications to numerical studies of an off-shore platform model. Structural parameters and sea conditions are referred to the Baltic jack-up drilling platform. The sudy aims at the influence of particular basic variables on static and dynamic response as well as the probability of failure due to water waves and wind loads. The paper presents the sensitivity approach to a generalized eigenvalue problem and evaluation of the performace functions. The first order time-invariant problems of structural reliability analysis are under concern

Implementation of natural and mathematical education – a client of observations

Niniejszy artykuł zawiera rozważania na temat tego, czy można realizować zagadnienie dotyczące przyrody i matematyki w edukacji, czy realizacja ta może mieć miejsce już w wieku przedszkolnym oraz jak realizować zajęcia przyrodnicze i matematyczne, korzystając z dostępnych pomocy dydaktycznych. Autorzy stawiają następującą hipotezę: realizację edukacji przyrodniczej w połączeniu z edukacją matematyczną można rozpocząć u dzieci przedszkolnych (3–4 lata), wykorzystując dostępne środki dydaktyczne w postaci zabaw lub gier oraz innych elementów technicznych. W treści artykułu podawane są argumenty na popieracie tej hipotezy oraz przykłady środków dydaktycznych do jej realizacji.Is it possible to implement the issue of nature and mathematics in education? An interesting question is the time to start this education. Can you start pre-school education in these areas? How to carry out these activities using the available teaching aids? Authors make a hypothesis: science education combined with mathematical education can be started with preschool children (3–4 years old), using the available didactic resources in the form of games or games, and other technical elements. The content provides examples supporting the hypothesis and examples of didactic measures for its implementation