Advancing the circular economy Reverse logistics and remanufacturing of dieselparticle filters

The Circular economy (CE) is an economic system created as an alternative to the unsustainable linear economy. CE and its business models aims to deal with the challenges as resource depletion, waste creation and over consumption by closing the material loop. CE is today practiced using different business models. One such business model is remanufacturing. A business model that has gained a lot of attention in different industries, especially in the vehicle industry. The vehicle industry, is an industry that use a lot of materials, and have a huge impact on the environment, and with the use of remanufacturing, it accomplishes to reduce material usage and decrease environmental impacts. This creates the need to look further into the remanufacturing of vehicle parts, and the focus of this thesis is remanufacturing of more diesel particle filters in the Swedish market. The thesis involves three actors, Volvo Cars, Stena Recycling Sverige, and UBD Cleantech. The study originates from Giab godsinlösen Nordic AB, that had the assumption of that there are valuable streams of diesel particle filters that currently are not collected but could be collected for remanufacturing. This study goes through literature of different concepts with key concepts of drivers and barriers for remanufacturing in the vehicle sector. This to identify what drivers and barriers there are for remanufacturing in the vehicle sector. This is followed by interviews with representatives at Stena Recycling Sverige, Volvo Cars and UBD Cleantech to examine the possibilities to collect more diesel particle filters for remanufacturing. The findings show that there are established cooperations that could enable remanufacturing of more diesel particle filters. But barriers such as the customer demand, storing and sorting can be a difficulty to overcome. However, drivers such as the environmental incentive and laws and regulation is positive for it. The conclusion and recommendations suggest further research in evaluating the quality of the filters, and the customer demand for them, but also to research other actors such as car dismantlers and car workshops that are related to the collection of diesel particle filters

Data-centric Misbehavior Detection in VANETs

Detecting misbehavior (such as transmissions of false information) in vehicular ad hoc networks (VANETs) is very important problem with wide range of implications including safety related and congestion avoidance applications. We discuss several limitations of existing misbehavior detection schemes (MDS) designed for VANETs. Most MDS are concerned with detection of malicious nodes. In most situations, vehicles would send wrong information because of selfish reasons of their owners, e.g. for gaining access to a particular lane. Because of this (\emph{rational behavior}), it is more important to detect false information than to identify misbehaving nodes. We introduce the concept of data-centric misbehavior detection and propose algorithms which detect false alert messages and misbehaving nodes by observing their actions after sending out the alert messages. With the data-centric MDS, each node can independently decide whether an information received is correct or false. The decision is based on the consistency of recent messages and new alert with reported and estimated vehicle positions. No voting or majority decisions is needed, making our MDS resilient to Sybil attacks. Instead of revoking all the secret credentials of misbehaving nodes, as done in most schemes, we impose fines on misbehaving nodes (administered by the certification authority), discouraging them to act selfishly. This reduces the computation and communication costs involved in revoking all the secret credentials of misbehaving nodes.Comment: 12 page

A Security Architecture for Data Aggregation and Access Control in Smart Grids

We propose an integrated architecture for smart grids, that supports data aggregation and access control. Data can be aggregated by home area network, building area network and neighboring area network in such a way that the privacy of customers is protected. We use homomorphic encryption technique to achieve this. The consumer data that is collected is sent to the substations where it is monitored by remote terminal units (RTU). The proposed access control mechanism gives selective access to consumer data stored in data repositories and used by different smart grid users. Users can be maintenance units, utility centers, pricing estimator units or analyzing and prediction groups. We solve this problem of access control using cryptographic technique of attribute-based encryption. RTUs and users have attributes and cryptographic keys distributed by several key distribution centers (KDC). RTUs send data encrypted under a set of attributes. Users can decrypt information provided they have valid attributes. The access control scheme is distributed in nature and does not rely on a single KDC to distribute keys. Bobba \emph{et al.} \cite{BKAA09} proposed an access control scheme, which relies on a centralized KDC and is thus prone to single-point failure. The other requirement is that the KDC has to be online, during data transfer which is not required in our scheme. Our access control scheme is collusion resistant, meaning that users cannot collude and gain access to data, when they are not authorized to access. We theoretically analyze our schemes and show that the computation overheads are low enough to be carried out in smart grids. To the best of our knowledge, ours is the first work on smart grids, which integrates these two important security components (privacy preserving data aggregation and access control) and presents an overall security architecture in smart grids.Comment: 12 Pages, 3 figure

Smaller Connected Dominating Sets in Ad Hoc and Sensor Networks based on Coverage by Two-Hop Neighbors

In this paper, we focus on the construction of an efficient dominating set in ad hoc and sensor networks. A set of nodes is said to be dominating if each node is either itself dominant or neighbor of a dominant node. This set can for example be used for broadcasting, so the smaller the set is, the more efficient it is. As a basis for our work, we use a heuristics given by Dai and Wu for constructing such a set and propose an enhanced definition to obtain smaller sets. This approach, in conjunction with the elimination of message overhead by Stojmenovic, has been shown (in recent studies) to be an excellent compromise with respect to a wide range of metrics considered. In our new definition, a node u is not dominant if there exists in its 2-hop neighborhood a connected set of nodes with higher priorities that covers u and its 1-hop neighbors. This new rule uses the exact same level of information required by the original heuristics, only neighbors of nodes and neighbors of neighbors must be known to apply it, but it takes advantage of some knowledge originally not taken into account: 1-hop neighbors can be covered by some 2-hop neighbors. We give the proof that the set obtained with this new definition is a subset of the one obtained with Dai and Wu's heuristics. We also give the proof that our set is always dominating for any graph, and connected for any connected graph. Two versions were considered: with topological and positional information, which differ in whether or not nodes are aware of links between their 2-hop neighbors that are not 1-hop neighbors. An algorithm for applying the concept at each node is described. We finally provide experimental data that demonstrates the superiority of our rule in obtaining smaller dominating sets. A centralized algorithm was used as a benchmark in the comparison. The overhead of the size of connected dominating set was reduced by about 15% with the topological variant and by about 30% with the positional variant of our new definition

Optimal Transmission Radius for Energy Efficient Broadcasting Protocols in Ad Hoc and Sensor Networks

International audienceWe investigate the problem of minimum energy broadcasting in ad hoc networks where nodes have capability to adjust their transmission range. The minimal transmission energy needed for correct reception by neighbor at distance r is proportional to r^alpha + c_e, alpha and c_e being two environment-dependent constants. We demonstrate the existence of an optimal transmission radius, computed with a hexagonal tiling of the network area, that minimizes the total power consumption for a broadcasting task. This theoretically computed value is experimentally confirmed. The existing localized protocols are inferior to existing centralized protocols for dense networks. We present two localized broadcasting protocols, based on derived 'target' radius, that remain competitive for all network densities. The first one, TR-LBOP, computes the minimal radius needed for connectivity and increases it up to the target one after having applied a neighbor elimination scheme on a reduced subset of direct neighbors. In the second one, TR-DS, each node first considers only neighbors whose distance is no greater than the target radius (which depends on the power consumption model used), and neighbors in a localized connected topological structure such as RNG or LMST. Then, a connected dominating set is constructed using this subgraph. Nodes not selected for the set may be sent to sleep mode. Nodes in selected dominating set apply TR-LBOP. This protocol is the first one to consider both activity scheduling and minimum energy consumption as one combined problem. Finally, some experimental results for both protocols are given, as well as comparisons with other existing protocols. Our analysis and protocols remain valid if energy needed for packet receptions is charged

Broadcasting in Hybrid Ad Hoc Networks.

In this paper, we consider hybrid ad hoc networks, which are composed of two kinds of nodes, regular ones and nodes with additional capabilities. For example, multi-hop cellular and wireless Internet networks consist of static or mobile nodes, and fixed access points which provide an access to an infrastructure. In such a network, each node may use direct or multihop link to connect to an access point, allowing a greater mobility. The goal of this paper is to provide protocols for broadcasting data in such an environment, by taking advantage of the presence of access points to optimize the broadcast, either from an energy consumption or from a latency point of view. We thus consider known protocols for pure ad hoc networks and adapt them to hybrid ad hoc networks. These protocols are the Blind Flooding, the Neighbor Elimination Scheme, the Multipoint Relay protocol and the generalized Self-Pruning Rule (algorithm that elects some dominant nodes to relay messages). We give some experimental data for these modified protocols to compare them to their original version, so that we are able to emphasize the gain obtained thanks to our proposed modifications

Introduction: Data Communication and Topology Algorithms for Sensor Networks

(First paragraph) We are very proud and honored to have been entrusted to be Guest Editors for this special issue. Papers were sought to comprehensively cover the algorithmic issues in the “hot” area of sensor networking. The concentration was on network layer problems, which can be divided into two groups: data communication problems and topology control problems. We wish to briefly introduce the five papers appearing in this special issue. They cover specific problems such as time division for reduced collision, fault tolerant clustering, self-stabilizing graph optimization algorithms, key pre-distribution for secure communication, and distributed storage based on spanning trees and triangulation

It is in the Air: Exploring Cleaner Air Pathways for Zabrze

Through research and interviews with several experts and stakeholders during the study visit in Zabrze, Poland, the main sources of air pollution in Zabrze and potential areas of intervention were identified. The project focused on residential heating in Zabrze, as coal based heating systems were identified as the main contributor to air pollution in the city. An alternative heating system scenario based on cleaner sources was suggested and compared to a baseline scenario in terms of cost and emission reduction potentials. Moreover, several enabling measures ranging from better data management to running campaigns to raise awareness and increased stakeholder collaboration was suggested in order to tackle the problem of air pollution