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Abstract: Background: City logistics is a critical component of urban economic development, as it optimizes supply chains, enhances customer satisfaction through reliable deliveries, and minimizes environmental impacts in densely populated areas. This field addresses various challenges, including traffic congestion, environmental concerns, noise pollution, and the crucial need for timely deliveries. Routing and scheduling are central to logistics operations, with modern software integrating time windows to meet precise scheduling demands driven by detailed customer requirements and operational efficiencies. Furthermore, advanced vehicle routing models now effectively simulate real-world factors such as traffic congestion, stochastic travel times, and dynamic product demands. Purpose: This paper aims to develop an algorithm that addresses the routing decisions. Our approach extends to the time dimension, considering travel times and customer service times within predefined time windows. Study design/methodology/approach: The proposed algorithm is structured to execute in iterative phases, aiming to optimize key logistical objectives. In order to generate competitive solutions, we seek to minimize the number of vehicles utilized and overall travel costs. The evaluation of solution space was conducted via Simulated Annealing. Findings/conclusions: The performance of the proposed algorithm, evaluated using the Gehring and Homberger benchmark instances for 200 customers, demonstrates its effectiveness. The algorithm successfully meets the target number of vehicles required, and the associated travel costs are on average within 1% of the best solutions reported in the relevant literature. Limitations/future research: Given the ongoing need for timely solutions from decision-makers, future research endeavors will focus on enhancing the computational efficiency of the algorithm. Additionally, incorporating more time-related features, such as stochastic travel times, could further improve the algorithm's real-time applicability.
Keywords: city logistics, vehicle routing, simulated annealing, time windows, scheduling
Published in DKUM: 27.03.2025; Views: 0; Downloads: 1
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Abstract: The use of extended standard functional analysis of maintenance in the design phase of vehicle structure analysis is presented for the first time, where a matrix of the degree of importance of modules or parts, a matrix size between costs and benefits (costs–benefits), and a logistic support matrix (support index and repair time) are used. The use of these methods allows a designer to be able to determine, in the very early phase of the construction process, the important factors (structure, component price, reliability, repair costs, response time, logistic supportability) that have a major impact on vehicle maintenance. Extended functional analysis also allows us to define critical structures in the project specification of vehicles. A crucial issue in functional analysis is the very extensive implementation of research, drawing conclusions and findings with the basic goal of determining a set of indicators for the verification of assumptions and hypotheses.
Keywords: maintenance, functional analysis, maintenance, vehicle design, structure design
Published in DKUM: 30.09.2024; Views: 0; Downloads: 7
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Abstract: Vehicle is an important element of transport; and its financing especially in road transport comes in 3 ways; outright purchase, hire purchase and lease. Of all these three methods of road transport financing, leasing has attracted little attention in Nigeria transport research. This study was carried out to examine the development, types and form, operating characteristics and problems of vehicle lease in Lagos State, Nigeria. Aggregate number of vehicle leasing companies in Nigeria from inception to 2018 was obtained from corporate affairs commission (CAC). Four prominent vehicle leasing companies: Cashlink Leasing Plc (CLP), NIKKY Taurus Ltd (NTL), C & I Leasing (CIL) and SAMTL Leasing Ltd (SLL) were purposively selected for the operating characteristics and challenges of the leasing companies. 298 structured questionnaires were administered to the staffs of the selected companies seeking the types and forms of lease and challenges encountered in the course of operation using stratified and simple random samplings techniques. Vehicle leasing started in Nigeria from 1986 with the likes of pine hill leasing, Cashlink leasing, VT leasing in Lagos. Within 1986 and 2018, it has spread to 23 different urban cities and the number has increased to 297 companies in 2018. Operating and finance leases exist in the industry with majority of 91.6% of the companies practice operating lease. The staff strength and fleet size level of the leasing companies varies overtime but positively significant to their operations. However, poor pricing of lease service, inadequate finance of vehicle, default in payment of rental charges and high cost of maintenance minimize leasing service efficiency and effectiveness. It is recommended that government should provide subvention for vehicles acquisition, face-off of racketing vehicles from cites and legislate policy to regulate operational activities (entry and exit) of the companies.
Keywords: leasing companies, Nigeria, operating characteristics, vehicle leasing
Published in DKUM: 22.08.2024; Views: 52; Downloads: 7
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Abstract: Road transport is showing growth in the period of globalization. Its task is to transport cargo as well as people to the required location within the shortest possible time and at the lowest price. Thus, road transport plays a crucial role in enabling the globalization to be developed and improved. However, the internal combustion engine hat prevail among the vehicles of freight and passenger transport are the producers of gaseous emissions from the exhaust gases. Many developed countries of the world has committed themselves, inter alia also trough the Paris Agreement, to reduce global warming, and thus to reduce the production of harmful gaseous emissions. The result is the endeavour to replace the internal combustion engine vehicles that burn carbon fuels with the vehicles powered by electric motors consuming electric energy. The reason of such trying claims that road transport using the internal combustion engine vehicles is environmentally aggressive, and the problem would not be solved by implementation of the vehicles with electric motors. Such claim is based on the fact that an electric car does not produce any of primary emissions. From an overall perspective, it is also necessary to take into account secondary emissions that are produced during the electric energy production by which is the vehicle with electric motor powered. The purpose of this article is to assume the possibility of reducing global pollution by replacing the internal combustion engine vehicles with the vehicles powered by electric motors in dependence with producing the emissions during the production of electric energy.
Keywords: electric energy, emissions, electric vehicle, internal combustion engine, global pollution
Published in DKUM: 22.08.2024; Views: 43; Downloads: 8
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Abstract: This paper presents automated storage systems with shuttles integrated with hoisted carriage for successful application in intralogistics. The first part of the paper presents classic and advanced AVS/RS along with specific intralogistics automation systems known as AutoStore from Swisslog and Skypod from Exotec. The second part of the paper focuses on an advanced system with shuttle vehicles capable of serving multiple tiers of the storage rack. An analytical model for the shuttle vehicles capable of serving multiple tiers of the storage rack is presented, which is based on (i) the sequences of acceleration, constant velocity and deceleration, and (ii) randomised assignment policy. Based on the presented model, the expected Single Command (SC) and Dual Command (DC) travel (cycle) time as well as the throughput performance of the shuttle vehicles capable of serving several tiers of warehouse, could be calculated. A programme code in MATLAB has been presented for the computation of throughput performances of automated storage systems with shuttles integrated with hoisted carriage capable of serving several tiers of the storage rack.
Keywords: analytical and numerical model, automated vehicle-storage and retrieval systems AVS/RS, automated warehouses, cycle time and throughput performance, shuttles integrated with hoisted carriage
Published in DKUM: 26.06.2024; Views: 162; Downloads: 16
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