Pri spodbujanju rabe javnega potniškega prometa ima pomembno vlogo razumevanje razmer, ki jih sistem zagotavlja za potnika. Na izbiro potovalnega načina vplivajo številni dejavniki, med katerimi se ...kot pomembna izkazuje konkurenčnost potovalnega časa ali potovalne hitrosti. Pri njenem izračunu si lahko zaradi razširjenosti elektronskih plačilnih sistemov pomagamo z zbranimi podatki validacij uporabnikov. S tem lahko na podlagi dejanskih potovanj izračunamo njihovo hitrost. V okviru raziskave smo na primeru avtobusnega sistema v Ljubljani analizirali vse vožnje, opravljene na tipičen dan. Na podlagi vstopnih in izstopnih podatkov o avtobusni vožnji smo izračunali opravljeno razdaljo, čas, potreben za pot, in hitrost opravljenih poti. Primerjali smo še, kako hitro bi lahko potniki poti, prevožene z avtobusom, opravili s kolesom ali peš. Ugotovili smo, da je hitrost obravnavanih potovanj z avtobusom odvisna od dolžine potovanja. Pri daljših potovanjih se hitrost povečuje. Kolo je hitrejše na vseh razdaljah, vendar pri večjih razdaljah postane manj sprejemljiva izbira. Hoja je na obravnavanih razdaljah do 2 km glede hitrosti konkurenčna le v manjšem deležu poti. Z opravljenimi analizami nam je uspelo s podatki, ki se zbirajo zaradi elektronskega plačevanja storitve, pridobiti uporaben vpogled v uporabniško učinkovitost sistema javnega prometa, kar je v prihodnje lahko uporabno pri načrtovanju izboljšav sistema.
In this research, a cryogenically cooled, near-dry, wire-cut, electrical discharge machining (CNDWEDM) investigation was performed using air, oxygen, and helium gases mixed with the minimum quantity ...of dielectric water as the working medium to cut Inconel-718 alloy with a molybdenum wire tool. All the experiments have been performed using the –150 °C temperature of the liquid-nitrogen-cooled wire electrode. The comparative analysis of the wire wear ratio (WWR), and the material removal rate (MRR) have been performed using an L27 orthogonal array. The air/gas pressure, mixing water-flow rate, spark current, and pulse duration are considered as influencing parameters on the cutting characteristics. It was observed from a comparative analysis that the WWR of oxygen-mist and helium-mist CNDWEDM processes are 30.39 % and 27.91 % higher than air-mist CNDWEDM, respectively. The MRR of the oxygen-mist and helium-mist CNDWEDM processes are 7.09 % and 3.60 % higher than the air-mist CNDWEDM, respectively. The contributions of the process parameters on the MRR and WWR for all three dielectric media have also been illustrated. It was observed from scanning electron microscope (SEM) images that the crater size in the wire tool of the oxygen-mist CNDWEDM is higher than the crater-size of the wire in the air-mist and helium-mist CNDWEDM.
Different cooling rates, such as room temperature water cooling (WQ), furnace cooling (FC), and water cooling + furnace cooling (FC +WQ), were introduced to study the effect on the solution-treated ...Mg-9Gd-4Y-2Zn-0.5Zr (w/%) alloy microstructure and mechanical properties. The grain size decreases as the cooling rate increases. With the lengthening of the cooling process time, the LPSO phase had enough time to nucleate and diffuse, the LPSO (long-period stacking order) phase filled the whole matrix crystal grains at the same time. In the process of furnace cooling and water cooling, the brightness of the LPSO phase was different, so it could be seen that the cooling rate would affect the contrast and morphology of the LPSO phase. The tensile yield strengths of the samples cooled with the furnace were better than those of the water-cooled samples, but their ultimate tensile strength and elongation to failure were poor. The fracture modes of the samples under different cooling rates were all subject to cleavage fracture, and the number and area of the cleavage planes and cleavage steps increased with the decrease of cooling speed, and the tearing area decreased, resulting in poor ultimate tensile strength and stretchability.
In this paper, the alternate immersion corrosion test of Cr-Mo-V series SDCM steel for hot stamping was carried out, and different stresses were loaded with self-made fixture. The results shown that ...regardless of hardness and stress, the corrosion mode of the material is uniform corrosion. Stress could significantly increase the corrosion rate, with lower hardness and higher corrosion rate. Because of the existence of Corrosion Removal Layer (CRL), the maximum corrosion pit depth would be reduced. The maximum corrosion pit depth and Corrosion Pit density (CPD, ρv) were used to describe the degree of corrosion damage. From low to high hardness, the CPD ρv and corrosion resistance increased gradually. With the increased of tempering temperature, the hardness decreased, and the percentage of carbide area in the field of view increased from 16.36% to 24.32%. The irregular spherical carbide M23(C, N)6 rich in Cr coarsens and consumes Cr element in the material, which lead to the decrease of corrosion resistance. Through the polarization curve of the dynamic potential, we known that the current density was increased with the hardness decreased, from 28.53 μA/mm2 to 40.93 μA/mm2.
In order to study the electrochemical corrosion law for the 13Cr stainless-steel tubing material in a high-speed Cl-containing liquid, a high-speed-flow experiment and a small three-electrode system, ...embedded in a small pipe, were used. The open circuit potential (OCP), polarization curve (PC) and electrochemical impedance spectroscopy (EIS) of the stainless-steel surface were tested in a medium with a flow velocity ranging from 10 to 22 m/s containing 1 w/% and 2 w/% of NaCl. By comparing it with the changes in the electrochemical-reaction parameters of the material in distilled water, the results of the experiment including the critical flow velocity, the change of corrosion rate and the electrochemical-reaction control steps were obtained. By theoretically solving the frictional force of the liquid against the wall surface and the adsorption capacity of the oxide film, and assuming that the oxide film is a macromolecular combination, the relationship between the adsorption capacity of different surface films and the critical flow velocity in the high-speed pipe flow was established. The results of this experiment and calculation can provide a preliminary prediction of the critical flow velocity corresponding to the inflection point of the wall-surface corrosion rate in an industrial pipe flow, thereby improving the process parameters and reducing the wall damage.
PDF
