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Scheduling technique of route vehicles on duplicating stretches

100%

Azemsha S. , Kravchenya I. , Vovk Y. , Lyashuk O. , Vovk I.

Zeszyty Naukowe. Transport / Politechnika Śląska

2021

tom z. 113

5--16

Schedule optimization is a proven strategy to improve service quality for public transport networks. However, current research mostly optimizes schedule design using prior knowledge of users’ routings, ignoring the optimization of public transport schedules on duplicating stretches of route vehicles. This article presents a new alignment technique of time intervals between consecutive vehicles of different routes on duplicating stretches, considering existing public transport networks in attaining optimization of public transport schedule. Scheduling technique of route vehicles on duplicating stretches includes some steps: analysis of public transport network and determining a lot of duplicating stretches, calculation of the optimal time intervals among arrivals of route vehicles and alignment of these intervals among consecutive route vehicles on duplicating stretches, realization simulation model of urban passenger transport within the simulation modeling system of GPSS World. Furthermore, testing the optimization technique of route vehicle scheduling, analysis of the quality of adjusted schedule with route vehicles of different kinds included, and determining the optimization efficiency for duplicating stretches. The adjusting technique of urban passenger transport schedule allows to increase movement steadiness of consecutive vehicles of different routes on duplicating stretches, adjust traffic intervals for each route, shorten the traffic load on stations, reducing idle time and queue lengths of route vehicles in front of transport stops and also minimize waiting time for route vehicle by those passengers who can be transported along several routes. Improving the bus schedule on duplicating stretches in Gomel is illustrated demonstrating the technique developed. This scheduling technique can be used by carriers and transport operators to improve the quality of services provided.

Method of calculating the design parameters of a modulator anti-lock braking system with a high flow of working fluid

86%

Zhilevich M. , Ermilov S. , Kapski D. , Vovk Y. , Lyashuk O. , Vovk I.

Zeszyty Naukowe. Transport / Politechnika Śląska

2021

tom z. 110

199--210

The design dimensions of the executive hydraulic cylinders of the brake system of heavy-duty mining dump trucks cause high fluid flow during the braking process. Therefore, dimensions of the anti-blocking system modulator spool pair require unique electromagnets or hydraulic amplifiers to control. These solutions do not allow the required modulator performance. Thus, a modulator scheme with a division of the flow of fluid from the source to the brake cylinders was developed. This scheme allows during emergency braking passing, an additional amount of fluid to cylinders through the valve, installed parallel to the main valve upon pressure increase phase and controlled by the pressure difference. The task is to develop a method for calculating the main structural dimensions of a modulator. The calculation of the valve of the second cascade, installed in parallel to the main stage, is carried out for the emergency braking mode with the maximum flow rate to ensure the required performance of the braking system. The balance of fluid flows equations is compiled at the key points. The flow rate of the fluid through each of the valves is determined by the Torricelli formula, and the pressure difference across the valves is assuned equal. The obtained relations allows building a family of Q-p curves, which can be used to select the diameter and stroke of the additional valve depending on the flow rate in the brake system.

Complex evaluation of the efficiency of urban consolidation centers at the micro level

86%

Savchenko L. , Grygorak M. , Polishchuk V. , Vovk Y. , Lyashuk O. , Vovk I. , Khudobei R.

Zeszyty Naukowe. Transport / Politechnika Śląska

2022

tom z. 115

135--159

A methodical approach for the determination of economic and socio-environmental costs in the application of the city consolidation center at the micro level was proposed and tested on real data. Two options of urban delivery of small shipments are considered, in particular, for e-commerce - direct delivery and delivery through the micro-consolidation center. The system of indicators proposed in this work allows a detailed assessment of the economic component of direct and consolidated delivery, including transportation costs, the functioning of the consolidation center costs and costs for pedestrian delivery to the residential district customers. Socio-economic indicators allow considering the interests of other residents of the city, suffering from a dense traffic flow and harmful emissions from freight vehicles. The proposed method of integrated assessment was tested on real data of a micro district of the city. The results made it possible to estimate the proportion of each component of expenditures in the economic, socio-environmental and total costs for both delivery options. The analysis of the sensitivity of costs to changes in the input parameters showed the difference in the strength of influence, and the rating of influencing factors. The proposed method allows us to estimate the economic costs of all participants in the urban delivery process for small shipments, as well as to prove the rationality of using micro-consolidation to serve a micro district of a large city.