3 research outputs found
The multi-vehicle profitable pick up and delivery routing problem with uncertain travel times
Abstract This paper addresses a variant of the known selective pickup and delivery problem with time windows. In this problem, a fleet composed of several vehicles with a given capacity should satisfy a set of customers requests consisting in transporting goods from a supplier (pickup location) to a customer (delivery location). The selective aspect consists in choosing the customers to be served on the basis of the profit collected for the service. Motivated by urban settings, wherein road congestion is an important issue, in this paper, we address the profitable pickup and delivery problem with time windows with uncertain travel times. The problem under this assumption, becomes much more involved. The goal is to find the solution that maximizes the net profit, expressed as the difference between the collected revenue, the route cost and the cost associated to the violation the time windows. This study introduces the problem and develops a solution approach to solve it. Very preliminary tests are performed in order to show the efficiency of developed method to cope with the problem at hand
Lithography and etching-free microfabrication of silicon carbide on insulator using direct UV laser ablation
Silicon carbide (SiC)âbased microsystems are promising alternatives for siliconâbased counterparts in a wide range of applications aiming at conditions of high temperature, high corrosion, and extreme vibration/shock. However, its high resistance to chemical substances makes the fabrication of SiC particularly challenging and less costâeffective. To date, most SiC micromachining processes require timeâconsuming and highâcost SiC dryâetching steps followed by metal wet etching, which slows down the prototyping and characterization process of SiC devices. This work presents a lithography and etchingâfree microfabrication for 3CâSiC on insulatorâbased microelectromechanical systems (MEMS) devices. In particular, a direct laser ablation technique to replace the conventional lithography and etching processes to form functional SiC devices from 3CâSiCâonâglass wafers is used. Utilizing a single lineâcutting mode, both metal contact shapes and SiC microstructures can be patterned simultaneously with a remarkably fast speed of over 20âcmâsâ1. As a proof of concept, several SiC microdevices, including temperature sensors, strain sensors, and microheaters, are demonstrated, showing the potential of the proposed technique for rapid and reliable prototyping of SiCâbased MEMS