•A novel design for heavy haul locomotive equipped with a flywheel energy storage system is proposed.•The integrated intelligent traction control system was developed.•A flywheel energy storage ...system has been tested through a simulation process.•The developed hybrid system was verified using an existing heavy haul railway route.•Fuel efficiency analysis confirms advantages of the hybrid design.
At the present time, trains in heavy haul operations are typically hauled by several diesel-electric locomotives coupled in a multiple unit. This paper studies the case of a typical consist of three Co–Co diesel-electric locomotives, and considers replacing one unit with an alternative version, with the same design parameters, except that the diesel-electric plant is replaced with flywheel energy storage equipment. The intelligent traction and energy control system installed in this unit is integrated into the multiple-unit control to allow redistribution of the power between all units. In order to verify the proposed design, a three-stage investigation has been performed as described in this paper. The initial stage studies a possible configuration of the flywheel energy storage system by detailed modelling of the proposed intelligent traction and energy control system. The second stage includes the investigation and estimation of possible energy flows using a longitudinal train dynamics simulation. The final stage compares the conventional and the proposed locomotive configurations considering two parameters: fuel efficiency and emissions reduction.
To understand the effect of locomotive dynamic behaviour on track damage, a great number of train operational parameters should be considered in the analysis. Two of the critical parameters are based ...on the introduction of friction-creep curves and in-train forces in the locomotive models. Due to the high costs of locomotive field-testing programs, this paper proposes a methodology that focuses on the introduction of friction measurements, performed with an experimental tribometer, and estimates in-train forces from locomotive/track multibody simulations. Two implementation cases, dry and lubricated friction conditions, are presented in this paper.
•The approach allows to deliver actual creep force characteristics at the wheel-rail interface without locomotive field test measurements.•Track damage simulation methodology for locomotives operating on specifically defined heavy haul routes.•Locomotive model considers influence of the Extended Contact modelling and traction algorithm on wear processes.
A special case study of a rail transport consist comprised of 11 wagons on three-piece bogies was carried out using advanced multi-body vehicle simulations to evaluate if the safety and stability of ...the wagons would be compromised by loading 39 continuous welded rails on the wagon decks. Each rail was 139 m long and laterally fastened to the wagon decks. The wagon model components, including a car body, two bolsters, 4 sideframes and 4 wheelsets, were connected by non-linear spring and damping elements. A non-linear coupler was used to connect the adjacent wagon models. A twist simulation for a single wagon model was conducted and the results were compared with experimental data for validation. The lateral stability analysis found that the lowest critical hunting speed was 90 km/h for the empty wagon model, which satisfies the current operational speed range from 0 to 70 km/h. Safety simulations were conducted on the curved track geometry modelled from the actual track alignment and included FRA Class 4 track irregularities. The safety simulation results indicated that the 11-wagon consist performed within the maximum safety criteria limits as stipulated in the AS7509:2017 standard.
Generally, rail has been losing its market share of bulk freight transport. Australian railways have an opportunity to improve the performance and meet the freight transport challenges of the ...twenty-first century, but a particular challenge is older infrastructure and networks with lower utilisation. Railway systems constructed in the 1800s, included numerous small radius curves, steeper grades and sub-standard formation, which would nowadays likely require additional maintenance funding to ensure the track is maintained at the required standard. As each train type applies a different quantifiable level of track damage for a given track geometry, and as the cost to repair/maintain this track is known, then it is possible to develop a transparent cost model to estimate the incremental infrastructure costs for each train type. Therefore, a wear/damage model was selected based on data derived from train simulations and track degradation analysis. This model provides an indication of the expected infrastructure maintenance budget based on train types (train configurations, vehicle axle loads, bogie parameters and wheel profiles), operational requirements (volumes, speeds) and the local track characteristics (track geometry, sleeper type, ballast/formation parameters and rail profiles). While, track damage models are currently available for railway vehicles on passenger networks, comprehensive heavy haul track damage models are still in their infancy. This paper publishes a summarised review from the first phase of this project.
Heavy haul railway track infrastructure are commonly equipped with balloon loops to allow trains to be loaded/unloaded and/or to reverse the direction of travel. The slow operational speed of trains ...on these sharp curves results in some unique issues regarding the wear process between wheels and rails. A wagon dynamic system model has been applied to simulate the dynamic behaviour in order to study the wheel–rail contact wear conditions. A wheel–rail wear index is used to assess the wear severity. The simulation shows that the lubrication to reduce the wheel–rail contact friction coefficient can significantly reduce the wear severity. Furthermore, the effects of important parameters on wheel–rail contact wear including curve radius, wagon speed and track superelevation have also been considered.
The OH-initiated photo-oxidation of piperidine and the photolysis of 1-nitrosopiperidine were investigated in a large atmospheric simulation chamber and in theoretical calculations based on ...CCSD(T*)-F12a/aug-cc-pVTZ//M062X/aug-cc-pVTZ quantum chemistry results and master equation modeling of the pivotal reaction steps. The rate coefficient for the reaction of piperidine with OH radicals was determined by the relative rate method to be k OH‑piperidine = (1.19 ± 0.27) × 10–10 cm3 molecule–1 s–1 at 304 ± 2 K and 1014 ± 2 hPa. Product studies show the piperidine + OH reaction to proceed via H-abstraction from both CH2 and NH groups, resulting in the formation of the corresponding imine (2,3,4,5-tetrahydropyridine) as the major product and in the nitramine (1-nitropiperidine) and nitrosamine (1-nitrosopiperidine) as minor products. Analysis of 1-nitrosopiperidine photolysis experiments under natural sunlight conditions gave the relative rates j rel = j 1‑nitrosoperidine/j NO2 = 0.342 ± 0.007, k 3/k 4a = 0.53 ± 0.05 and k 2/k 4a = (7.66 ± 0.18) × 10–8 that were subsequently employed in modeling the piperidine photo-oxidation experiments, from which the initial branchings between H-abstraction from the NH and CH2 groups, k N–H/k tot = 0.38 ± 0.08 and k C2–H/k tot = 0.49 ± 0.19, were derived. All photo-oxidation experiments were accompanied by particle formation that was initiated by the acid–base reaction of piperidine with nitric acid. Primary photo-oxidation products including both 1-nitrosopiperidine and 1-nitropiperidine were detected in the particles formed. Quantum chemistry calculations on the OH initiated atmospheric photo-oxidation of piperidine suggest the branching in the initial H-abstraction routes to be ∼35% N1, ∼50% C2, ∼13% C3, and ∼2% C4. The theoretical study produced an atmospheric photo-oxidation mechanism, according to which H-abstraction from the C2 position predominantly leads to 2,3,4,5-tetrahydropyridine and H-abstraction from the C3 position results in ring opening followed by a complex autoxidation, of which the first few steps are mapped in detail. H-abstraction from the C4 position is shown to result mainly in the formation of piperidin-4-one and 2,3,4,5-tetrahydropyridin-4-ol, whereas H-abstraction from N1 under atmospheric conditions primarily leads to 2,3,4,5-tetrahydropyridine and in minor amounts of 1-nitrosopiperidine and 1-nitropiperidine. The calculated rate coefficient for the piperidine + OH reaction agrees with the experimental value within 35%, and aligning the theoretical numbers to the experimental value results in k(T) = 2.46 × 10–12 × exp(486 K/T) cm3 molecule–1 s–1 (200–400 K).
The OH-initiated photo-oxidation of piperazine and 1-nitropiperazine as well as the photolysis of 1-nitrosopiperazine were investigated in a large atmospheric simulation chamber. The rate coefficient ...for the reaction of piperazine with OH radicals was determined by the relative rate method to be k OH‑piperazine = (2.8 ± 0.6) × 10–10 cm3 molecule–1 s–1 at 307 ± 2 K and 1014 ± 2 hPa. Product studies showed the piperazine + OH reaction to proceed both via C–H and N–H abstraction, resulting in the formation of 1,2,3,6-tetrahydropyrazine as the major product and in 1-nitropiperazine and 1-nitrosopiperazine as minor products. The branching in the piperazinyl radical reactions with NO, NO2, and O2 was obtained from 1-nitrosopiperazine photolysis experiments and employed analyses of the 1-nitropiperazine and 1-nitrosopiperazine temporal profiles observed during piperazine photo-oxidation. The derived initial branching between N–H and C–H abstraction by OH radicals, k N–H/(k N–H + k C–H), was 0.18 ± 0.04. All experiments were accompanied by substantial aerosol formation that was initiated by the reaction of piperazine with nitric acid. Both primary and secondary photo-oxidation products including 1-nitropiperazine and 1,4-dinitropiperazine were detected in the aerosol particles formed. Corroborating atmospheric photo-oxidation schemes for piperazine and 1-nitropiperazine were derived from M06-2X/aug-cc-pVTZ quantum chemistry calculations and master equation modeling of the pivotal reaction steps. The atmospheric chemistry of piperazine is evaluated, and a validated chemical mechanism for implementation in dispersion models is presented.
Seasonal Use of Latrines by Bobcats HILTS, DYLAN J.; GEHRING, THOMAS M.; NIELSEN, CLAYTON K. ...
The Journal of wildlife management,
11/2020, Letnik:
84, Številka:
8
Journal Article
Recenzirano
Latrines serve as important communication networks among felids for transmitting information relative to social dominance, reproductive status, and defense of hunting areas. During January ...2011–August 2012, we monitored 10 bobcat (Lynx rufus) latrines in the northern Lower Peninsula (NLP) of Michigan, USA, using motion-sensitive cameras to estimate bobcat visitation and scat deposition rates among 3 biological seasons (mating, kitten-rearing, non-mating). Bobcat visitation rates differed among the 3 seasons. We found equal number of visits during the mating and kitten-rearing seasons, and lower visitation rates during the non-mating season. Scat deposition rates differed among the 3 seasons. We found a net gain of scats deposited during the mating and non-mating seasons, whereas there was a net loss of scats during the kitten-rearing season. An artificial latrine protocol we developed yielded visitation at 4 of 12 artificial latrine sites. Monitoring natural and artificial latrines during the mating and kitten-rearing seasons could provide valuable data for managing bobcat populations.
The OH-initiated photo-oxidation of piperazine was investigated in chamber experiments at the European Photoreactor (EUPHORE) in Spain and by quantum chemistry methods. The rate coefficient for ...reaction with OH radicals was determined by the relative rate method to be k OH-piperazine = (2.8 0.6) 10-10 cm 3 molecule-1 s-1 at 307 ± 2 K and 1014 ± 2 hPa. The reaction was found to proceed via both C-H and N-H abstraction, the latter resulting in the formation of nitroso-and nitro-piperazine. The reaction in the EUPHORE chamber was accompanied by strong particle formation which was induced by an acid-base reaction between photochemically formed nitric acid and the
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