An exact approach for the grocery delivery problem in urban areas

In this paper, we face the problem of delivering a given amount of goods in urban areas in a business-to-consumer (B2C) electronic commerce (EC) environment. This problem can be considered as a particular case of vehicle routing problem. As a novel issue, here we have to determine the fleet of no homogeneous vehicles to be used for satisfying the demands of clients coming from grocery e-channels, and their related itineraries, given the traveling limits imposed by the urban government; in fact, commercial vehicles are not allowed to go everywhere and can travel only in restricted daily time windows, according to their pollution emissions. We have to minimize the overall distribution costs, taking into account traveling components and setup ones, together with operative aspects and environmental issues; customer requirements, vehicle capacity and daily shift constraints have to be satisfied too. We outline the main characteristics of the problem in a B2C EC environment and propose a mixed integer linear programming model to solve this NP-hard problem. Computational results of test bed cases related to different sized transportation networks and delivery demands are presented and analyzed with respect to the fleet of vehicles chosen for satisfying the customer demand and the street traffic limitations. Then, a realistic case study derived from the e-distribution channel of a grocery company of Genoa, Italy, is reported. Considerations about CPU time and optimality gap are also given with the idea of making the proposed model effectively used and solved with any commercial software

SCHOOL FOOD SERVICE, HOSPITAL AND HEALTCARE: NEW GUIDELINES ON NATIONAL LAW AND VETERINARY 488/99

The author reviews the guidelines of the National school catering, hospital and health care, recently published. Show only the aspect of Article 59 of the Law n.488/99, given the complexity of the issue and the rampant protectionism dictated more by ethnic and ethical and environmental claims, which has prompted some governments to fear the food self-sufficiency, in sharp contrast with European free trade rules. The issues related to Article 59 of Law No 488 of 23 December 1999 and the amendment to Article 123 of Law 388/2000, concerning the development of organic farming and quality, are commented in relation to the cd Procurement Code, in particular the legislative decree n.163 dated 12 April 2006 and subsequent amendments and additions, noting criticism of the check up as required by Article 59 and the low involvement of the veterinary hygienist

ACRYLAMIDE, FOOD AND EUROPEAN COMMUNITIES RECOMMENDATION

The exposure, often deceitful, to the acrylamide has determined notable apprehension in many consumers, so much that the Committee of the European Communities has financed the project HEATOX and has emanated the recommendation 2007/331. It is ascertained that proposed strategies have not brought to great changes in the food process chains, and neither in the traditional catering and housewife, for which more incisive measures are wished

The Wounded Healer: A Phenomenological Study on Hospital Nurses Who Contracted COVID-19

Since the pandemic began nurses were at the forefront of the crisis, assisting countless COVID-19 patients, facing unpreparedness, social and family isolation, and lack of protective equipment. Of all health professionals, nurses were those most frequently infected. Research on healthcare professionals' experience of the pandemic and how it may have influenced their life and work is sparse. No study has focused on the experiences of nurses who contracted COVID-19 and afterwards returned to caring for patients with COVID-19. The purpose of this study was therefore to explore the lived personal and professional experiences of such nurses, and to describe the impact it had on their ways of approaching patients, caring for them, and practicing their profession. A phenomenological study was conducted with 54 nurses, through 20 individual interviews and 4 focus groups. The main finding is that the nurses who contracted COVID-19 became "wounded healers": they survived and recovered, but remained "wounded" by the experience, and returned to caring for patients as "healers," with increased compassion and attention to basic needs. Through this life-changing experience they strengthened their ability to build therapeutic relationships with patients and re-discovered fundamental values of nursing. These are some of the ways in which nurses can express most profoundly the ethics of work done well

A biased random-key genetic algorithm for the set orienteering problem

This paper addresses the Set Orienteering Problem which is a generalization of the Orienteering Problem where the customers are grouped in clusters, and the profit associated with each cluster is collected by visiting at least one of the customers in the respective cluster. The problem consists of finding a tour that maximizes the collected profit but, since the cost of the tour is limited by a threshold, only a subset of clusters can usually be visited. We propose a Biased Random-Key Genetic Algorithm for solving the Set Orienteering Problem in which three local search procedures are applied to improve the fitness of the chromosomes. In addition, we introduced three rules useful to reduce the size of the instances and to speed up the resolution of the problem. Finally, a hashtable is used to quickly retrieve the information that are required several times during the computation. The computational results, carried out on benchmark instances, show that our algorithm is significantly faster than the other algorithms, proposed in the literature, and it provides solutions very close to the best-known ones

A Lagrangian approach for the minimum spanning tree problem with conflicting edge pairs

This article addresses the minimum spanning tree problem with conflicting edge pairs, a variant of the classical minimum spanning tree where, given a list of conflicting edges, the goal is to find the cheapest spanning tree with no edges in conflict. We adopt a Lagrangian relaxation approach together with a dual ascent and a subgradient procedure to find tight lower bounds on the optimal solution. The algorithm is also equipped with a heuristics approach which provides an upper bound by removing the conflicts from possible infeasible solutions met during the calculation of the lower bounds. The computational results, carried out on benchmark instances, show that the proposed algorithm finds the optimal solutions on several instances. Moreover, the lower bounds it provides are much more accurate than ones provided by other Lagrangian approaches available in the literature and they are computed is much less time

Column Generation Embedding Carousel Greedy for the Maximum Network Lifetime Problem with Interference Constraints

We aim to maximize the operational time of a network of sensors, which are used to monitor a predefined set of target locations. The classical approach proposed in the literature consists in individuating subsets of sensors (covers) that can individually monitor the targets, and in assigning appropriate activation times to each cover. Indeed, since sensors may belong to multiple covers, it is important to make sure that their overall battery capacities are not violated. We consider additional constraints that prohibit certain sensors to appear in the same cover, since they would interfere with each other. We propose a Column Generation approach, in which the pricing subproblem is solved either exactly or heuristically by means of a recently introduced technique to enhance basic greedy algorithms, known as Carousel Greedy. Our experiments show the effectiveness of this approach

Optimization of sensor battery charging to maximize lifetime in a wireless sensors network

The maximum network lifetime is a well known and studied optimization problem. The aim is to appropriately schedule the activation intervals of the individual sensing devices composing a wireless sensor network used for monitoring purposes, in order to keep the network operational for the longest period of time (network lifetime). In this work, we extend this problem by taking into account the issue of charging the sensor batteries. More specifically, it has to be decided how much charge should be provided to each sensor, given the existence of a charging device with limited energy availability. An exact column generation algorithm embedding a genetic algorithm for the subproblem is proposed. Computational results reveal that by appropriately choosing the charge levels, remarkable network lifetime improvements can be obtained, in particular when the available energy is scarce