Transporto mašinų transmisijos elementų dinaminių procesų tyrimas

Disertacijoje nagrinėjamos transporto mašinų transmisijų būklės diagnozavimo problemos. Tyrimo objektas yra dažniausiai gendantys transmisijų elementai, riedėjimo guoliai ir krumpliaratinės pavaros. Nuo jų techninės būklės priklauso viso įrenginio darbingumas. Jų būklės pasikeitimo stebėjimas leidžia racionaliai išnaudoti įrenginio resursą, sumažinti prastovų laiką. Pagrindinis disertacijos tikslas – sukurti metodikas ir algoritmus, skirtus įrenginio pažaidoms nustatyti ir jų vystymuisi stebėti. Darbe sprendžiami keli uždaviniai: kuriami transmisijos elementų su pažaidomis matematiniai modeliai, tiriama pažaidų įtaka dinaminių parametrų pokyčiams. Atliekami transmisijos elementų su pažaidomis dinaminių procesų eksperimentiniai tyrimai. Tiriamas virpesių matavimo ir akustinės emisijos metodų tinkamumas transporto mašinų transmisijų elementų diagnostikai. Remiantis atliktais teorinių ir eksperimentinių tyrimų rezultatais kuriama transporto mašinų transmisijos elementų diagnostikos metodika. Disertaciją sudaro įvadas, keturi skyriai, rezultatų apibendrinimas, literatūros ir autoriaus publikacijų disertacijos tema sąrašai ir priedai. Įvadiniame skyriuje aptariama tiriamoji problema, darbo aktualumas. Aprašomas tyrimų objektas, formuluojamas darbo tikslas ir uždaviniai. Aprašomi naudojami tyrimų metodai ir įranga, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Įvado pabaigoje pristatomos disertacijos tema autoriaus paskelbtos publikacijos ir pranešimai konferencijose bei disertacijos struktūra. Pirmasis skyrius yra skirtas literatūros apžvalgai. Jame pateikta esamų transporto priemonių transmisijų elementų matematinių modelių ir eksperimentinių tyrimų nagrinėjama tematika apžvalga. Antrajame skyriuje pateikti riedėjimo guolio ir tiesiakrumplės pavaros matematiniai modeliai. Trečiajame skyriuje pateikti riedėjimo guolio, tiesiakrumplės ir hipoidinės pavarų eksperimentiniai tyrimai. Ketvirtajame skyriuje pateikta matematinio modeliavimo ir eksperimentinių tyrimų rezultatų analizė. Disertacijos tema paskelbti 4 straipsniai: du – žurnaluose, įtrauktuose į Thomson ISI sąrašą, du – kituose recenzuojamuose žurnaluose. Disertacijos tema perskaityti du pranešimai tarptautinėse konferencijose

Variability of gravel pavement roughness: an analysis of the impact on vehicle dynamic response and driving comfort

Gravel pavement has lower construction costs but poorer performance than asphalt surfaces on roads. It also emits dust and deforms under the impact of vehicle loads and ambient air factors; the resulting ripples and ruts constantly deepen, and therefore increase vehicle vibrations and fuel consumption, and reduce safe driving speed and comfort. In this study, existing pavement quality evaluation indexes are analysed, and a methodology for adapting them for roads with gravel pavement is proposed. We report the measured wave depth and length of gravel pavement profile using the straightedge method on a 160 m long road section at three stages of road utilization. The measured pavement elevation was processed according to ISO 8608, and the frequency response of a vehicle was investigated using simulations in MATLAB/Simulink. The international roughness index (IRI) analysis showed that a speed of 30-45 km/h instead of 80 km/h provided the objective results of the IRI calculation on the flexible pavement due to the decreasing velocity of a vehicle’s unsprung mass on a more deteriorated road pavement state. The influence of the corrugation phenomenon of gravel pavement was explored, identifying specific driving safety and comfort cases. Finally, an increase in the dynamic load coefficient (DLC) at a low speed of 30 km/h on the most deteriorated pavement and a high speed of 90 km/h on the middle-quality pavement demonstrated the demand for timely gravel pavement maintenance and the complicated prediction of a safe driving speed for drivers. The main relevant objectives of this study are the adaptation of a road roughness indicator to gravel pavement, including the evaluation of vehicle dynamic responses at different speeds and pavement deterioration states

Local determinants of driving behaviours: installation theory interventions to reduce fuel consumption among truck drivers in Colombia

Eco-driving has been linked to considerable reductions in negative externalities and costs for transportation companies, employees and communities (including fuel consumption, safety and emission benefits). Nevertheless, some of the biggest challenges to its implementation are related to promoting behavioural change among drivers. This paper presents the results of three behavioural field interventions that were successful to improve fuel efficiency in heavy freight transportation. The interventions brought further improvement even though the target company already had strong training, incentive, control and feedback procedures in place. The Installation Theory framework and the Subjective Evidence Based Ethnography (SEBE) technique were used to systematically analyse determinants of driving behaviours, and to design cost-effective behavioural interventions based on social norms. The effects of three interventions were then tested using a pre-test post-test control group design among 211 drivers of the company. Results show significant decreases in average monthly fuel consumption of up to 4% in month 1 and up to 4.5% in month 3. Our findings show (with certain qualifications), that the Installation Theory framework and social norm interventions can be a cost-effective method to improve fuel efficiency in road freight transport companies, even when strong training, incentive, control and feedback procedures are already in place

MCDM Evaluation of Asset-Based Road Freight Transport Companies Using Key Drivers that Influence the Enterprise Value

Business owners are trying to enhance company value by developing growth strategies. Besides, they need to know what supports and drives the attractiveness to potential investors. Previously to determine company value, only financial drivers were used. These are essential drivers; however, even they do not reflect the overall situation. This paper proposes a novel approach for the solution of the problem of business valuation by taking into account both financial and non-financial drivers and by using several MCDM (multiple criteria decision making) methods simultaneously both for establishing weights and for the evaluation itself. World-leading road freight transport companies were selected for a case study. MCDM methods were used for determining the weights of the drivers and comparing the listed companies. Key drivers were identified, and the ranking of companies is provided

Development of a contactless sensor system to support rail track geometry on-board monitoring

This paper is focused on the ongoing research, within a work package of the Shift2Rail project Assets4Rail, related to the development of an on-board contactless sensor system able to measure the wheel's transversal position in relation to the rail in order to support track geometry measurements. In particular, this research work focuses on developing a sensor system to support track geometry monitoring performed by the master system under development in other Shift2Rail projects. The aim is to develop a sensor system to detect the relative transversal position between the wheelset and the rail, suitable for the use on commercial (in-service) vehicles. In fact, a possible track geometry monitoring system alternative to the sophisticated and expensive optical/inertial systems and suitable for use on commercial vehicles, could be based on the measurement of accelerations. However, some parameters of the track geometry, such as lateral alignment, are extremely difficult to determine through the measurement of accelerations. In this case, it is necessary to find an innovative sensor system able to determine the wheel's transversal position in relation to the rail. For this reason, this project intends to focus on innovative systems that allow the detection of the wheel-track position by avoiding the optical/inertial systems already used on diagnostic trains. After a state-of-the-art overview on the potentially applicable technologies for the sensor system to be developed, a corresponding analytical tool for comparison of contactless sensors to choose the most suitable technology has been developed and two candidate technologies (stereo and thermal cameras) have been selected and assessed by means of a test platform in the facilities laboratory of VGTU (Vilnius Tech). This work will be the basis for developing a concept design of the sensor system together with a montage solution, which will be finally tested on a vehicle in real operation conditions

Feasibility of a neural network-based virtual sensor for vehicle unsprung mass relative velocity estimation

With the automotive industry moving towards automated driving, sensing is increasingly important in enabling technology. The virtual sensors allow data fusion from various vehicle sensors and provide a prediction for measurement that is hard or too expensive to measure in another way or in the case of demand on continuous detection. In this paper, virtual sensing is discussed for the case of vehicle suspension control, where information about the relative velocity of the unsprung mass for each vehicle corner is required. The corresponding goal can be identified as a regression task with multi-input sequence input. The hypothesis is that the state-of-art method of Bidirectional Long–Short Term Memory (BiLSTM) can solve it. In this paper, a virtual sensor has been proposed and developed by training a neural network model. The simulations have been performed using an experimentally validated full vehicle model in IPG Carmaker. Simulations provided the reference data which were used for Neural Network (NN) training. The extensive dataset covering 26 scenarios has been used to obtain training, validation and testing data. The Bayesian Search was used to select the best neural network structure using root mean square error as a metric. The best network is made of 167 BiLSTM, 256 fully connected hidden units and 4 output units. Error histograms and spectral analysis of the predicted signal compared to the reference signal are presented. The results demonstrate the good applicability of neural network-based virtual sensors to estimate vehicle unsprung mass relative velocity

Investigation of recoil force influence on dynamic parameters of carrier M113

Dynamic processes of the armored personnel carrier M113 are investigated in this paper. The model of the system is reduced to seven degrees of freedom (DOF). Six schemes of different integrations were investigated; it was determined that integration schemes with variable time steps allow to reduce calculation time within the applicable range of the calculation error. The weapon’s impact on the dynamic processes of the vehicle is investigated on the uneven terrain. The influence of the standard weaponry on the oscillation peculiarities of the M113 when the vehicle is standing still, moves on the uneven terrain is analyzed. Also, possibilities to use 30 mm cannon on the carrier M113 are examined

Deep Learning based Virtual Point Tracking for Real-Time Target-less Dynamic Displacement Measurement in Railway Applications

In the application of computer-vision based displacement measurement, an optical target is usually required to prove the reference. In the case that the optical target cannot be attached to the measuring objective, edge detection, feature matching and template matching are the most common approaches in target-less photogrammetry. However, their performance significantly relies on parameter settings. This becomes problematic in dynamic scenes where complicated background texture exists and varies over time. To tackle this issue, we propose virtual point tracking for real-time target-less dynamic displacement measurement, incorporating deep learning techniques and domain knowledge. Our approach consists of three steps: 1) automatic calibration for detection of region of interest; 2) virtual point detection for each video frame using deep convolutional neural network; 3) domain-knowledge based rule engine for point tracking in adjacent frames. The proposed approach can be executed on an edge computer in a real-time manner (i.e. over 30 frames per second). We demonstrate our approach for a railway application, where the lateral displacement of the wheel on the rail is measured during operation. We also implement an algorithm using template matching and line detection as the baseline for comparison. The numerical experiments have been performed to evaluate the performance and the latency of our approach in the harsh railway environment with noisy and varying backgrounds

The dynamic behaviour of a wheel flat of a railway vehicle and rail irregularities

The article examines a mathematical model for the system ‘Railway Vehicle Wheel–Track’ that allows examining the interaction between a wheel flat and a rail in the vertical plane. The dynamics of the railway track is described using the finite element method while that of the soil and vehicle is expressed applying discrete elements. The model is used for assessing physical and mechanical properties, the roughness of the wheel, rail surface and their geometry. The analysis of the dynamic system ‘Railway Vehicle Wheel–Track’ has been conducted. In accordance with the revised method, forces arising from contact between the wheel flat and the rail are possible to be determined in a more precise way. The article presents and analyses the results of a mathematical experiment on this system

Investigation of the hydrodynamic processes of a centrifugal pump in a geothermal system

The hydrodynamic and thermodynamic processes of geothermal well extraction are investigated and presented in this paper. The paper presents mathematical models for a multi-level centrifugal pump and pipeline system. The mathematical models were used to evaluate gas (nitrogen) emission in water and its effects on hydrodynamic processes. Experimental studies and mathematical modelling showed that the gas content of the fluid increases the pressure and flow pulsations within a centrifugal pump. The variation in the height of the liquid column in extraction has an influence on characteristics of the multistage centrifugal pump used in wells. First published online 29 March 201