Far-field spectral characterization of conical emission and filamentation in Kerr media

By use of an imaging spectrometer we map the far-field ($\theta-\lambda$) spectra of 200 fs optical pulses that have undergone beam collapse and filamentation in a Kerr medium. By studying the evolution of the spectra with increasing input power and using a model based on stationary linear asymptotic wave modes, we are able to trace a consistent model of optical beam collapse high-lighting the interplay between conical emission, multiple pulse splitting and other effects such as spatial chirp.Comment: 8 pages, 9 figure

Conical-emission and shock-front dynamics in femtosecond laser-pulse filamentation

We investigate both experimentally and numerically the space-time dynamics of an ultrashort laser pulse during self-focusing and nonlinear propagation in water by means of a time-gated angular-spectrum characterization. The results identify the formation of shock fronts on both trailing and leading edges of the wave packet that are due to the formation of subluminal and superluminal group velocity intensity peaks, sustained by conical emission

Selected transverse stability problems related to articulated vehicles built to carry liquid cargo

The paper deals with problems connected with the transportation of dangerous cargo in articulated road tankers. The problems related to transverse stability of articulated vehicles have been discussed. The rig and experimental tests carried out to explore the transverse stability problem have been presented. Attention has been paid to the specificity of articulated road tankers. The necessity of rig and field testing of vehicles of this kind has been emphasized. The specificity of the transportation of such articulated vehicles by sea has been highlighted

Engine and Emission Performance of Renewable Fuels in a Small Displacement Turbocharged Diesel Engine

A reduction in emissions in transportation is paramount to achieve full compliance with the European Union’s 2050 targets. In this framework, a great boost to the carbon dioxide (CO2) emission of internal combustion engines fueled by petroleum-derived fuels can be obtained through the adoption of biomass-derived fuels that can be employed in conventional series production engine vehicles. This paper presents the results of an experimental activity on a two-cylinder turbocharged common rail diesel engine, whose main application is for urban mobility, fueled with renewable fuels: Neste MY Renewable Diesel and Eni HVOlution. Aimed at analyzing the potential employment of renewable fuels as drop-in alternative fuels, the engine performance and emissions were investigated under fixed settings of the injection parameters, in the complete range of the engine speed, at the full pedal position. The comparison with the data from tests in which the engine was fueled with fossil diesel highlighted minimal differences in the performance outcomes, while significant differences were observed in the emissions results. In more detail, there were reduced carbon monoxide (CO) emissions (HVO produced using EcofiningTM technology retained better behavior in relation to HVO produced using the NEXBTLTM technology), advantages in hydrocarbon (HC) and nitrogen oxide (NOx) emissions (HVO from NESTE Oil performed better than HVO from ENI), a decrease in the particle mass and number emissions (HVO from EcofiningTM technology was characterized by a lower particle number and court mean diameter in relation to HVO from the NEXBTLTM technology). The results highlight that an optimization of the engine settings based on the specific properties of each fuel could allow us to take full advantage of these fuels in reducing the environmental impact of cars

Vairuotojų profesionalų darbingumo pokyčių analizė

The causes of traffic events are predetermined by abundant factors that affect simultaneously the driver and the vehicle involved in traffic. According to the statistics, the most important is the human factor, i.e. the totality of physical and psychological characteristics predetermining successful activities of a driver. Namely the human factor is the principal potential for increasing a reliability of drivers. Improper behaviour of drivers on driving most frequently is the principal cause of traffic events. One of the ways for minimizing the number of a driver's errors is an assessment of the factors that predetermine the driver's behaviour on the road to the maximum possible extent. Emergency situations and their consequences directly depend on proper and well-timed actions of the driver. The article presents a study on professional drivers' working capacity, defines the main criteria influencing it and provides an overview of the general impact of professional drivers' performance on road safety. A questionnaire survey method, aimed at identifying professional drivers' working capacity changes during on-duty hours, was applied in this article. It has been established how the respondents - professional drivers of the Joint Stock Company "Vilnius Public Transport" (Lith. - UAB .Vilniausviesasistransportas") - evaluate their working capacity changes according to the following indicators: direct fatigue, physiological changes during a work shift, the fatigue during the first (5-14 h.) and the second (14-23 h.) work shift, as well as the probability of alcoholic beverage consumption during off-duty (rest) hours.Kelių eismo įvykių priežastis lemia daugybė veiksnių, vienu metu veikiančių vairuotoją ir transporto priemonę. Remiantis statistiniais duomenimis, svarbiausią reikšmę turi žmogiškasis veiksnys t.y. visuma asmens fizinių ir psichologinių savybių, lemiančių sėkmingą vairuotojo darbą. Būtent žmogiškasis veiksnys yra potencialas, padedantis didinti vairuotojų patikimumą. Netinkamas vairuotojų elgesys uždažnias itampa pagrindine kelių eismo įvykių priežastimi. Vienas iš būdų sumažinti vairuotojo klaidas – maksimaliai įvertinti veiksnius, lemiančius jo elgesį kelyje. Avarinė situacijos ir jų pasekmės tiesiogiai priklauso nuo tinkamų ir savalaikių vairuotojo veiksmų. Straipsnyje nagrinėjama vairuotojų profesionalų darbingumas, apibrėžti pagrindiniai kriterijai, turintys įtakos darbingumui bei apžvelgta bendra vairuotojų profesionalų darbingumo įtaka eismo saugumui. Straipsnyje panaudotas vairuotojų profesionalų anketavimo metodas, kurio tikslas yra indentifikuoti vairuotojų profesionalų darbingumo pokyčius darbometu. Nustatyta kaip UAB “Vilniaus viešasis transportas” vairuotojai profesionalai – respondenta ivertina savo darbingumo pokyčius pagal šiuos rodiklius: tiesioginį nuovargį, fiziologinius pokyčius darbo pamainos laikotarpiu, nuovargį pirmos (5–14 val.) ir antros (14–23 val.) darbo pamainų metu, alkoholinių gėrimų vartojimo tikimybę nedarbo (poilsio) metu