https://faculty.biu.ac.il/~shnaidh/zooloo/trnsprt2/Location-routing-%20Issues,%20models%20and%20methods.pdf

Location-routing: Issues, models and methods

Network functions virtualization (NFV) is a new network architecture framework where network function that traditionally used dedicated hardware (middleboxes or network appliances) are now implemented in software that runs on top of general purpose hardware such as high volume server. NFV emerges as an initiative from the industry (network operators, carriers, and manufacturers) in order to increase the deployment flexibility and integration of new network services with increased agility within operator’s networks and to obtain significant reductions in operating expenditures and capital expenditures. NFV promotes virtualizing network functions such as transcoders, firewalls, and load balancers, among others, which were carried out by specialized hardware devices and migrating them to software-based appliances. One of the main challenges for the deployment of NFV is the resource allocation of demanded network services in NFV-based network infrastructures. This challenge has been called the NFV resource allocation (NFV-RA) problem. This paper presents a comprehensive state of the art of NFV-RA by introducing a novel classification of the main approaches that pose solutions to solve it. This paper also presents the research challenges that are still subject of future investigation in the NFV-RA realm.

Resource Allocation in NFV: A Comprehensive Survey

Green Logistics has emerged as the new agenda item in supply chain management. The traditional objective of distribution management has been upgraded to minimizing system-wide costs related to economic and environmental issues. Reflecting the environmental sensitivity of vehicle routing problems (VRP), an extensive literature review of Green Vehicle Routing Problems (GVRP) is presented. We provide a classification of GVRP that categorizes GVRP into Green-VRP, Pollution Routing Problem, VRP in Reverse Logistics, and suggest research gaps between its state and richer models describing the complexity in real-world cases. The purpose is to review the most up-to-date state-of-the-art of GVRP, discuss how the traditional VRP variants can interact with GVRP and offer an insight into the next wave of research into GVRP. It is hoped that OR/MS researchers together with logistics practitioners can be inspired and cooperate to contribute to a sustainable industry.

Survey of Green Vehicle Routing Problem: Past and future trends

Personnel scheduling: A literature review

The fifth generation (5G) wireless network technology is to be standardized by 2020, where main goals are to improve capacity, reliability, and energy efficiency, while reducing latency and massively increasing connection density. An integral part of 5G is the capability to transmit touch perception type real-time communication empowered by applicable robotics and haptics equipment at the network edge. In this regard, we need drastic changes in network architecture including core and radio access network (RAN) for achieving end-to-end latency on the order of 1 ms. In this paper, we present a detailed survey on the emerging technologies to achieve low latency communications considering three different solution domains: 1) RAN; 2) core network; and 3) caching. We also present a general overview of major 5G cellular network elements such as software defined network, network function virtualization, caching, and mobile edge computing capable of meeting latency and other 5G requirements.

A Survey on Low Latency Towards 5G: RAN, Core Network and Caching Solutions

https://www.di.unipi.it/~gallo/Papers/ObnoxiousFacilityLocation.pdf

Discrete facility location and routing of obnoxious activities

This article introduces a game-theoretic approach for allocating protection resources among the components of a network so as to maximize its robustness to external disruptions. Specifically, we consider shortest-path networks where disruptions may result in traffic flow delays through the affected components or even in the complete loss of some elements. A multilevel program is proposed to identify the set of components to harden so as to minimize the length of the shortest path between a supply node and a demand node after a worst-case disruption of some unprotected components. An implicit enumeration algorithm is then developed to solve the multilevel problem to optimality. The approach is streamlined by solving the lower-level interdiction problem heuristically at each node of an enumeration tree and by using some variable fixing rules to reduce the dimension of the lower-level problems. A thorough computational investigation demonstrates that the proposed solution method is able to identify optimal protection strategies for networks of significant size. The paper is concluded with a study of the sensitivity of the solution approach to variations of the problem parameters such as the level of disruption and protective resources and the distribution of the arc lengths and delays.

/pdf/optimal-allocation-of-protective-resources-in-shortest-path-2o3bzz3kky.pdf

Optimal Allocation of Protective Resources in Shortest-Path Networks

The design of efficient home care services is a quite recent and challenging field of study. We propose an integrated approach that jointly addresses: i the assignment of operators to patients so as to guarantee the compatibility between skills associated with operators and patient visits; ii the scheduling of the visits in a given planning horizon; and iii the determination of the operator tours in every day of the planning horizon. The main home care problem we investigate refers to providers dedicated to palliative care and terminal patients. In this context, balancing objective functions are particularly relevant. Therefore, two balancing functions are studied, i.e., maxmin, which maximizes the minimum operator utilization factor, and minmax, which minimizes the maximum operator utilization factor. In both cases, the concept of pattern is introduced as a key tool to jointly address assignment, scheduling, and routing decisions, where a pattern specifies a possible schedule for skilled visits. The approach we propose is, however, able to cope with peculiarities from other home care contexts. Model extensions to handle scenarios other than the palliative one are discussed in the paper.

Extensive computational results are reported both on palliative home care instances based on real data, and on two real-world data sets from the literature, related to contexts very different from the palliative one. For both data sets the proposed approach is able to find solutions of good quality. In the palliative context, the results show that the selection of the pattern generation policy is crucial to solve large instances efficiently. Furthermore, the maxmin criterion is able to return more balanced solutions; i.e., the difference between the maximum and the minimum operator utilization factors is very small. On the other hand, the minmax criterion is more suitable for minimizing the operating costs, since it computes solutions with smaller total traveled time.

/pdf/joint-assignment-scheduling-and-routing-models-to-home-care-22v49jrwvf.pdf

Joint Assignment, Scheduling, and Routing Models to Home Care Optimization: A Pattern-Based Approach

The adoption of the virtualization paradigm in both computing and networking domains portends a landscape of heterogeneous service capabilities and resources pervasively distributed and interconnected and deeply integrated through the 5G network infrastructure. In this service ecosystem, dynamic service demand can be flexibly and elastically accomplished by composing heterogeneous services provisioned over a distributed and virtualized resource infrastructure. Indeed, with the term Virtual Functions we refer to virtual computing as well as network service capabilities (e.g., routers and middlebox functions provided as Virtual Network Functions). In order to cope with the increasingly resource intensive demand, these virtual functions will be deployed in distributed clusters of small-scale datacenters typically located in current exchanges at the network edge and will supplement those deployed in traditional large cloud datacenters. In this work we formulate the problem of composing, computing and networking Virtual Functions to select those nodes along the path that minimizes the overall latency (i.e. network and processing latency) in the above mentioned scenario. The optimization problem is formulated as a Resource Constrained Shortest Path problem on an auxiliary layered graph accordingly defined. The layered structure of the graph ensures that the order of VFs specified in the request is preserved. Additional constraints can be also taken into account in the graph construction phase. Finally, we provide a use case preliminary evaluation of the proposed model.

Latency-aware composition of Virtual Functions in 5G

The problem of finding a work assignment for airline crew members in a given time horizon is addressed. In the literature this problem is usually referred to as the airline crew rostering problem. It consists of constructing monthly schedules for crew members by assigning them pairings, rest periods, annual and sick leave, training periods, union activities, and so forth, so as to satisfy the collective agreements and security rules. We formulate the airline crew rostering problem as a 0-1 multicommodity flow problem where each employee corresponds to a commodity; determining a monthly schedule for an employee is the same as computing a path on a suitably defined graph while still satisfying union conventions. A preprocessing phase is performed that reduces the dimension of the graph. To tighten the linear programming formulation of our model, we propose some families of valid inequalities that have proved to be computationally effective. Some of them can be treated implicitly when constructing the graph. Computational results obtained with a commercial integer programming solver (CPLEX) are analyzed.

/pdf/a-multicommodity-flow-approach-to-the-crew-rostering-problem-2tq55trs5y.pdf

Paola Cappanera

Papers

Discrete facility location and routing of obnoxious activities

Optimal Allocation of Protective Resources in Shortest-Path Networks

Joint Assignment, Scheduling, and Routing Models to Home Care Optimization: A Pattern-Based Approach

Latency-aware composition of Virtual Functions in 5G

A Multicommodity Flow Approach to the Crew Rostering Problem