Specifying a hydraulic regenerative braking system for an articulated urban delivery vehicle
Previous research has shown that hydraulic systems offer potentially the lightest and smallest regenerative braking technology for heavy goods vehicles. This paper takes the most practical embodiment of a hydraulic system for an articulated urban delivery vehicle and investigates the best specification for the various components, based on a simulated stop-start cycle. The potential energy saving is quantified.
Factors influencing the energy consumption of road freight transport
Abstract Key factors that influence the energy consumption of heavy goods vehicles are investigated. These factors include engine efficiency, aerodynamic drag and rolling resistance, vehicle configuration (number of vehicle units), traffic congestion, speed, payload factors, and the use of regenerative braking. An accurate, validated model of the fuel consumption of a 38 tonne tractor-semitrailer vehicle is used as a basis to derive fuel consumption models of a number of other vehicle configurations. These models included a rigid four-axle truck with maximum gross vehicle mass (GVM) of 26 tonnes; a six-axle tractor semitrailer with GVM of 44 tonnes, with and without regenerative braking; a ‘B-double’ with GVM of 60 tonnes; and an ‘A-double’ with GVM of 82 tonnes. These vehicle models were driven over a simple hypothetical drive cycle with a fixed maximum speed and varying numbers of stops in a 10 km stretch of road. It is concluded that: (a) improving engine efficiency, unladen mass, rolling resistance, and aerodynamic drag can yield relatively small improvements in fuel consumption, compared with other factors; (b) larger vehicles are always significantly more energy-efficient than smaller ones when fully loaded; (c) transferring freight from articulated vehicles to smaller rigid vehicles for urban deliveries typically increases fuel consumption by approximately 35 per cent; (d) running vehicles partially loaded can increase the energy per unit freight task by up to 65 per cent; and (e) under urban start—stop conditions, the use of regenerative braking systems can reduce heavy vehicle fuel consumption by 25–35 per cent.
Using Activity Theory in Developing Instructial Tools for Project Management Studies
Competence and skills of the project manager are significant to project success. The skills needed in project managersâ work cannot be learned only by reading the books or a lecture hall; one learns them by practice. Therefore, an important challenge for educational institutions is to develop pedagogical practices that allow students to participate in working life projects and to confront real-life problems. Project-based learning (PBL) offers a model that enables students to practice the skills and competences needed in working life projects by utilizing real-world work assignments in time-limited projects. Using PBL method alone does not necessarily guarantee learning result. In order to be successful, PBL method requires effective and competent supervision and guidance of students as well as appropriate tools for instruction. In this study the concepts from activity theory (AT) are applied to development tools for supervising project-based learning.