Laurencas Raslavičius

Motor Biofuel-Powered CHP Plants—A Step Towards Sustainable Development of Rural Lithuania

Abstract This paper focuses on the benefits that can be attained from the correct option of small-scale combined heat and power plant (CHP) relative to fuel availability and sphere of application. The analysis serves as a means of highlighting some of the owners of large-scale farms as well as holders of industrial greenhouses that influence the penetration of small-scale cogeneration plants running on bio-based liquid fuels. The identification of the main influencing factors and their weight is the first step towards the implementation of a more coherent strategy, if the EC (European Commission) and national energy authorities wish for new small-scale cogeneration technologies to have a future in the context of sustainable development of rural Lithuania. Against this background, this paper aims at presenting the technical, environmental and economic aspects of the possibilities of utilizing biodiesel, biodiesel-conventional diesel blends and rapeseed oil in combined heat and power production as an issue ...

Assessment of bicycle–car accidents under four different types of collision

Bicycle riders are among the highest risk group in traffic. A cyclist simulation study captured kinematics and injuries to legs, pelvis, neck, and head for one human body size. We analyzed the number of parameters (forces acting on left and right tibia, head injury criterion, neck tensile force, neck shear force, and pelvic acceleration) for each of the four different cases: bicyclist ride out—residential driveway, motorist overtaking—undetected bicyclist, bicyclist left turn—same direction, and bicyclist right turn—opposite direction. The comparison of simulation outcomes for leg injuries with official hospital records has shown a very good correlation in terms of injury severity prediction. This study concludes that if countermeasures to prevent fatal cyclist injury in car impacts were to be concentrated on mitigating head and neck impact to the windscreen of the car, a dominant share of fatal cyclist crashes and severe traumatic head injury cases at collision speeds exceeding 40 km/h could be prevented.

Developing an Efficient Cover Cropping System for Organically Grown Barley

Spring barley (SB) (Hordeum vulgare L.) cultivar ‘Ūla’ is the most widely grown cereal in Lithuania (hereinafter LIT). Most of the SB varieties bred in LIT (‘Aidas,’ ‘Alsa,’ ‘Aura,’ and ‘Baronesse’) are suitable for growing organically. However, in contrast to conventional farming practices, they are considerably more sensitive to the organic farming conditions and lack of nitrogen required for weed suppression. One of the several organic solutions to the problem of spreading weeds lies in growing false flax (FF; Camelina sativa) as cover crop between the SB plantings. This paper aims to address two questions: 1) development of recommendations to achieve the best performance from a mixed seed drilling and 2) quantitative appraisal of the weed suppression level in mixed crop (FF+SB) against weed incidence in sole crop of SB. For this study, an experimental coulter with adjustable geometries based on a theoretical approach to characterize FF seed movement has been developed. According to laboratory test findings, three-year in-field research trials were conducted to combine both theoretical and practical aspects of integrated weed management. A series of experiments confirmed that FF could effectively limit the prevalence of weeds under certain soil properties and weather conditions typical to LIT. The main conclusion was that drilling FF in strips between SB rows reduced the amount of weeds by 1.79 times in relation to “no-FF” practices without a significant decrease in SB yield. The proposed weed management strategy is effective, reliable, practical, and economical.

Steep increases in biomass demand: the possibilities of short rotation coppice (SRC) agro-forestry

AbstractAt current usage levels, short rotation coppice (SRC) biomass could be considered as an untapped resource. There is a worldwide interest to extend its sustainable production significantly in a decade to come. However, the cultivation of energy crops is very site-specific and the exploitation of SRC biomass is a relatively new trend in biomass application for heat and power production with little information on its cultivation patterns and appropriate combustion technologies. In fact, documented biomass conversion technologies’ impacts in the energy sector and their commercialisation are limited. This paper aims to present a summary of technical characteristics for different biomass conversion technologies. These characteristics are not necessarily unique to all types and possible modifications of the biomass conversion technologies applied for many countries. However, the lack of technical knowledge have created situations that were previously impossible to be solved without the aid of numerous re...

Investigation of asphalt texture roughness on friction evolution for wheeled vehicles

AbstractNovelty of the research lies in understanding the safety advantages of asphalt made using advanced pavement design process – compact asphalt pavement installation. Variation of tyre–road friction coefficient for this type of pavement design is new and little-studied phenomenon. The present study focuses on the research into tyre–pavement interaction on dry asphalt pavement surfaces to quantify the effect of microprofile on vehicle performance in establishing its braking conditions. The data on a number of different indications (vehicle speed, adhesion coefficients calculated on the basis of braking and friction forces, maximum adhesion coefficient mmax and its ‘minimum’ value m100%) and measurement results generated using SRT-4 device for investigation of two road stretches at intervals of 100 m are presented in this paper. The interdependence analysis of statistical variables mmax and m100% has also been presented to exhibit the use of the method. Following statistical parameters are taken into a...

Energo-Mechanical Evaluation of Damage Growth and Fracture Initiation in Aviation Composite Structures

ABSTRACT The aim of the present paper is to (1) highlight the results of laboratory damage detection and monitoring in the aviation composite materials, during a mechanical testing constituted of multiple loadings, and (2) obtain a detailed understanding of damage evolution of composite specimens with regard to impact energy. Woven 12-ply glass fiber and 16-ply carbon fiber–reinforced epoxy composites (GFRP 92 125/L285/287 and CFRP 98 131/L285/287) were used as less studied subjects in research. This study explored the resistance to cracking and delamination of glass and carbon fiber laminates with the same resin system under low-load conditions. GRAPHICAL ABSTRACT

City transport analysis using the General Motors (GM) microscopic model

AbstractAutomobile, bus and trolleybus traffic flow in urban areas is increasing because of transport growth and continuous demand for it. The developing economy and changing social status of the population increases the need for mobility. Therefore, urban transport flow is increasing, resulting in traffic congestions, since the street network throughput in practice does not change. The negative effect caused by the traffic congestions is most notable in the largest cities, where traffic density is relatively high, with characteristically low and often variable speed (acceleration and deceleration). We present in this paper a modification of General Motors (GM) traffic flow simulation model in order to identify best possible prerequisites for traffic flow management. The forecasting model employs the following independent variables: vehicle movement speeds, service time (traffic light signal duration), traffic flow intensity, average service frequencies, and the lengths of formed queues. By specifying different functional forms of response time we propose a generalized methodology for traffic management and obtain a theory, which is demonstrated in this paper through both numerical simulation and theoretical analyses. The developed simulation model based on GM’s car following model shows good correlation to the field data. To this end, this paper presents a designed assessment method for the short-term congestion, expressing the negative impact of the transport system in monetary units.